Recent Advancements in DNA Damage-Transcription Crosstalk and High-Resolution Mapping of DNA Breaks.

PubMed

Vitelli, Valerio; Galbiati, Alessandro; Iannelli, Fabio; Pessina, Fabio; Sharma, Sheetal; d'Adda di Fagagna, Fabrizio

2017-08-31

Until recently, DNA damage arising from physiological DNA metabolism was considered a detrimental by-product for cells. However, an increasing amount of evidence has shown that DNA damage could have a positive role in transcription activation. In particular, DNA damage has been detected in transcriptional elements following different stimuli. These physiological DNA breaks are thought to be instrumental for the correct expression of genomic loci through different mechanisms. In this regard, although a plethora of methods are available to precisely map transcribed regions and transcription start sites, commonly used techniques for mapping DNA breaks lack sufficient resolution and sensitivity to draw a robust correlation between DNA damage generation and transcription. Recently, however, several methods have been developed to map DNA damage at single-nucleotide resolution, thus providing a new set of tools to correlate DNA damage and transcription. Here, we review how DNA damage can positively regulate transcription initiation, the current techniques for mapping DNA breaks at high resolution, and how these techniques can benefit future studies of DNA damage and transcription.

Breaking resolution limits in ultrafast electron diffraction and microscopy.

PubMed

Baum, Peter; Zewail, Ahmed H

2006-10-31

Ultrafast electron microscopy and diffraction are powerful techniques for the study of the time-resolved structures of molecules, materials, and biological systems. Central to these approaches is the use of ultrafast coherent electron packets. The electron pulses typically have an energy of 30 keV for diffraction and 100-200 keV for microscopy, corresponding to speeds of 33-70% of the speed of light. Although the spatial resolution can reach the atomic scale, the temporal resolution is limited by the pulse width and by the difference in group velocities of electrons and the light used to initiate the dynamical change. In this contribution, we introduce the concept of tilted optical pulses into diffraction and imaging techniques and demonstrate the methodology experimentally. These advances allow us to reach limits of time resolution down to regimes of a few femtoseconds and, possibly, attoseconds. With tilted pulses, every part of the sample is excited at precisely the same time as when the electrons arrive at the specimen. Here, this approach is demonstrated for the most unfavorable case of ultrafast crystallography. We also present a method for measuring the duration of electron packets by autocorrelating electron pulses in free space and without streaking, and we discuss the potential of tilting the electron pulses themselves for applications in domains involving nuclear and electron motions.

Deep Keck u-Band Imaging of the Hubble Ultra Deep Field: A Catalog of z ~ 3 Lyman Break Galaxies

NASA Astrophysics Data System (ADS)

Rafelski, Marc; Wolfe, Arthur M.; Cooke, Jeff; Chen, Hsiao-Wen; Armandroff, Taft E.; Wirth, Gregory D.

2009-10-01

We present a sample of 407 z ~ 3 Lyman break galaxies (LBGs) to a limiting isophotal u-band magnitude of 27.6 mag in the Hubble Ultra Deep Field. The LBGs are selected using a combination of photometric redshifts and the u-band drop-out technique enabled by the introduction of an extremely deep u-band image obtained with the Keck I telescope and the blue channel of the Low Resolution Imaging Spectrometer. The Keck u-band image, totaling 9 hr of integration time, has a 1σ depth of 30.7 mag arcsec-2, making it one of the most sensitive u-band images ever obtained. The u-band image also substantially improves the accuracy of photometric redshift measurements of ~50% of the z ~ 3 LBGs, significantly reducing the traditional degeneracy of colors between z ~ 3 and z ~ 0.2 galaxies. This sample provides the most sensitive, high-resolution multi-filter imaging of reliably identified z ~ 3 LBGs for morphological studies of galaxy formation and evolution and the star formation efficiency of gas at high redshift.

Infrared super-resolution imaging based on compressed sensing

NASA Astrophysics Data System (ADS)

Sui, Xiubao; Chen, Qian; Gu, Guohua; Shen, Xuewei

2014-03-01

The theoretical basis of traditional infrared super-resolution imaging method is Nyquist sampling theorem. The reconstruction premise is that the relative positions of the infrared objects in the low-resolution image sequences should keep fixed and the image restoration means is the inverse operation of ill-posed issues without fixed rules. The super-resolution reconstruction ability of the infrared image, algorithm's application area and stability of reconstruction algorithm are limited. To this end, we proposed super-resolution reconstruction method based on compressed sensing in this paper. In the method, we selected Toeplitz matrix as the measurement matrix and realized it by phase mask method. We researched complementary matching pursuit algorithm and selected it as the recovery algorithm. In order to adapt to the moving target and decrease imaging time, we take use of area infrared focal plane array to acquire multiple measurements at one time. Theoretically, the method breaks though Nyquist sampling theorem and can greatly improve the spatial resolution of the infrared image. The last image contrast and experiment data indicate that our method is effective in improving resolution of infrared images and is superior than some traditional super-resolution imaging method. The compressed sensing super-resolution method is expected to have a wide application prospect.

Breaking resolution limits in ultrafast electron diffraction and microscopy

PubMed Central

Baum, Peter; Zewail, Ahmed H.

2006-01-01

Ultrafast electron microscopy and diffraction are powerful techniques for the study of the time-resolved structures of molecules, materials, and biological systems. Central to these approaches is the use of ultrafast coherent electron packets. The electron pulses typically have an energy of 30 keV for diffraction and 100–200 keV for microscopy, corresponding to speeds of 33–70% of the speed of light. Although the spatial resolution can reach the atomic scale, the temporal resolution is limited by the pulse width and by the difference in group velocities of electrons and the light used to initiate the dynamical change. In this contribution, we introduce the concept of tilted optical pulses into diffraction and imaging techniques and demonstrate the methodology experimentally. These advances allow us to reach limits of time resolution down to regimes of a few femtoseconds and, possibly, attoseconds. With tilted pulses, every part of the sample is excited at precisely the same time as when the electrons arrive at the specimen. Here, this approach is demonstrated for the most unfavorable case of ultrafast crystallography. We also present a method for measuring the duration of electron packets by autocorrelating electron pulses in free space and without streaking, and we discuss the potential of tilting the electron pulses themselves for applications in domains involving nuclear and electron motions. PMID:17056711

Ultra-narrow pulse generator with precision-adjustable pulse width

NASA Astrophysics Data System (ADS)

Fu, Zaiming; Liu, Hanglin

2018-05-01

In this paper, a novel ultra-narrow pulse generation approach is proposed. It is based on the decomposition and synthesis of pulse edges. Through controlling their relative delay, an ultra-narrow pulse could be generated. By employing field programmable gate array digital synthesis technology, the implemented pulse generator is with programmable ability. The amplitude of pulse signals is controlled by the radio frequency amplifiers and bias tees, and high precision can be achieved. More importantly, the proposed approach can break through the limitation of device's propagation delay and optimize the resolution and the accuracy of the pulse width significantly. The implemented pulse generator has two channels, whose minimum pulse width, frequency range, and amplitude range are 100 ps, 15 MHz-1.5 GHz, and 0.1 Vpp-1.8 Vpp, respectively. Both resolution of pulse width and channel delay are 1 ps, and amplitude resolution is 10 mVpp.

Nonlinear photothermal Mid-Infrared Microspectroscopy with Superresolution

NASA Astrophysics Data System (ADS)

Erramilli, Shyamsunder; Mertiri, Alket; Liu, Hui; Totachawattana, Atcha; Hong, Mi; Sander, Michelle

2015-03-01

We describe a nonlinear method for breaking the diffraction limit in mid-infrared microscopy using nonlinear photothermal microspectroscopy. A Quantum Cascade Laser (QCL) tuned to an infrared active vibrational molecular normal mode is used as the pump laser. A low-phase noise Erbium-doped fiber (EDFL) laser is used as the probe. When the incident intensity of the mid-infrared pump laser is increased past a critical threshold, a nanobubble is nucleated, strongly modulating the scatter of the probe beam, in agreement with prior work. Remarkably, we have also found that the photothermal spectral signature of the mid-infrared absorption bifurcates and is strongly narrowed, consistent with an effective ``mean-field'' theory of the observed pitchfork bifurcation. This ultrasharp narrowing can be exploited to obtain mid-infrared images with a resolution that breaks the diffraction limit, without the need of mechanical scanning near-field probes. The method provides a powerful new tool for hyperspectral label-free mid-infrared imaging and characterization of biological tissues and materials science and engineering. We thank our collaborators H. Altug, L. D. Ziegler, J. Mertz, for their advice and generous loan of equipment.

Multiple focused EMAT designs for improved surface breaking defect characterization

NASA Astrophysics Data System (ADS)

Thring, C. B.; Fan, Y.; Edwards, R. S.

2017-02-01

Ultrasonic Rayleigh waves can be employed for the detection of surface breaking defects such as rolling contact fatigue and stress corrosion cracking. Electromagnetic Acoustic Transducers (EMATs) are well suited to this technique as they can directly generate Rayleigh waves within the sample without the requirement for wedges, and they are robust and inexpensive compared to laser ultrasonics. Three different EMAT coil types have been developed, and these are compared to assess their ability to detect and characterize small (down to 0.5 mm depth, 1 mm diameter) surface breaking defects in aluminium. These designs are: a pair of linear meander coils used in a pseudo-pulse-echo mode, a pair of focused meander coils also used in pseudo-pulse-echo mode, and a pair of focused racetrack coils used in pitch-catch mode. The linear meander coils are able to detect most of the defects tested, but have a much lower signal to noise ratio and give limited sizing information. The focused meander coils and the focused racetrack coils can detect all defects tested, but have the advantage that they can also characterize the defect sizes on the sample surface, and have a stronger sensitivity at their focal point. Measurements using all three EMAT designs are presented and compared for high resolution imaging of surface-breaking defects.

Enhanced labeling density and whole-cell 3D dSTORM imaging by repetitive labeling of target proteins.

PubMed

Venkataramani, Varun; Kardorff, Markus; Herrmannsdörfer, Frank; Wieneke, Ralph; Klein, Alina; Tampé, Robert; Heilemann, Mike; Kuner, Thomas

2018-04-03

With continuing advances in the resolving power of super-resolution microscopy, the inefficient labeling of proteins with suitable fluorophores becomes a limiting factor. For example, the low labeling density achieved with antibodies or small molecule tags limits attempts to reveal local protein nano-architecture of cellular compartments. On the other hand, high laser intensities cause photobleaching within and nearby an imaged region, thereby further reducing labeling density and impairing multi-plane whole-cell 3D super-resolution imaging. Here, we show that both labeling density and photobleaching can be addressed by repetitive application of trisNTA-fluorophore conjugates reversibly binding to a histidine-tagged protein by a novel approach called single-epitope repetitive imaging (SERI). For single-plane super-resolution microscopy, we demonstrate that, after multiple rounds of labeling and imaging, the signal density is increased. Using the same approach of repetitive imaging, washing and re-labeling, we demonstrate whole-cell 3D super-resolution imaging compensated for photobleaching above or below the imaging plane. This proof-of-principle study demonstrates that repetitive labeling of histidine-tagged proteins provides a versatile solution to break the 'labeling barrier' and to bypass photobleaching in multi-plane, whole-cell 3D experiments.

Breaking the diffraction limit of light-sheet fluorescence microscopy by RESOLFT

PubMed Central

Hoyer, Patrick; de Medeiros, Gustavo; Balázs, Bálint; Norlin, Nils; Besir, Christina; Hanne, Janina; Kräusslich, Hans-Georg; Engelhardt, Johann; Sahl, Steffen J.; Hell, Stefan W.; Hufnagel, Lars

2016-01-01

We present a plane-scanning RESOLFT [reversible saturable/switchable optical (fluorescence) transitions] light-sheet (LS) nanoscope, which fundamentally overcomes the diffraction barrier in the axial direction via confinement of the fluorescent molecular state to a sheet of subdiffraction thickness around the focal plane. To this end, reversibly switchable fluorophores located right above and below the focal plane are transferred to a nonfluorescent state at each scanning step. LS-RESOLFT nanoscopy offers wide-field 3D imaging of living biological specimens with low light dose and axial resolution far beyond the diffraction barrier. We demonstrate optical sections that are thinner by 5–12-fold compared with their conventional diffraction-limited LS analogs. PMID:26984498

Experimental evaluation of rigor mortis IX. The influence of the breaking (mechanical solution) on the development of rigor mortis.

PubMed

Krompecher, Thomas; Gilles, André; Brandt-Casadevall, Conception; Mangin, Patrice

2008-04-07

Objective measurements were carried out to study the possible re-establishment of rigor mortis on rats after "breaking" (mechanical solution). Our experiments showed that: *Cadaveric rigidity can re-establish after breaking. *A significant rigidity can reappear if the breaking occurs before the process is complete. *Rigidity will be considerably weaker after the breaking. *The time course of the intensity does not change in comparison to the controls: --the re-establishment begins immediately after the breaking; --maximal values are reached at the same time as in the controls; --the course of the resolution is the same as in the controls.

Temporal intensity interferometry for characterization of very narrow spectral lines

NASA Astrophysics Data System (ADS)

Tan, P. K.; Kurtsiefer, C.

2017-08-01

Some stellar objects exhibit very narrow spectral lines in the visible range additional to their blackbody radiation. Natural lasing has been suggested as a mechanism to explain narrow lines in Wolf-Rayet stars. However, the spectral resolution of conventional astronomical spectrographs is still about two orders of magnitude too low to test this hypothesis. We want to resolve the linewidth of narrow spectral emissions in starlight. A combination of spectral filtering with single-photon-level temporal correlation measurements breaks the resolution limit of wavelength-dispersing spectrographs by moving the linewidth measurement into the time domain. We demonstrate in a laboratory experiment that temporal intensity interferometry can determine a 20-MHz-wide linewidth of Doppler-broadened laser light and identify a coherent laser light contribution in a blackbody radiation background.

Influence of polarization characteristic of targets on synthetic aperture imaging ladar

NASA Astrophysics Data System (ADS)

Xu, Qian; Sun, Jianfeng; Lu, Zhiyong; Wang, Lijuan; Hou, Peipei; Lu, Wei; Liu, Liren

2017-09-01

Synthetic aperture imaging ladar (SAIL) is one of the most possible optical active imaging methods to break the diffraction limit and achieve super-resolution in a long distance. Nevertheless, two-dimensional reconstructed images of the natural targets have not been achieved. Polarization state change of the backscattered light, which is always determined by the interaction of the light and the materials on the target plane, will affect the imaging of SAIL. The Mueller matrices can describe the complex polarization features of the target reflection and treat this interaction. In this paper, a measurement of the Mueller matrices for different target materials will be designed, and the influences of polarization characteristic of targets on resolution element imaging in side-looking and down-looking SAILs will be theoretically analyzed.

Review of ultra-high density optical storage technologies for big data center

NASA Astrophysics Data System (ADS)

Hao, Ruan; Liu, Jie

2016-10-01

In big data center, optical storage technologies have many advantages, such as energy saving and long lifetime. However, how to improve the storage density of optical storage is still a huge challenge. Maybe the multilayer optical storage technology is the good candidate for big data center in the years to come. Due to the number of layers is primarily limited by transmission of each layer, the largest capacities of the multilayer disc are around 1 TB/disc and 10 TB/ cartridge. Holographic data storage (HDS) is a volumetric approach, but its storage capacity is also strictly limited by the diffractive nature of light. For a holographic disc with total thickness of 1.5mm, its potential capacities are not more than 4TB/disc and 40TB/ cartridge. In recent years, the development of super resolution optical storage technology has attracted more attentions. Super-resolution photoinduction-inhibition nanolithography (SPIN) technology with 9 nm feature size and 52nm two-line resolution was reported 3 years ago. However, turning this exciting principle into a real storage system is a huge challenge. It can be expected that in the future, the capacities of 10TB/disc and 100TB/cartridge can be achieved. More importantly, due to breaking the diffraction limit of light, SPIN technology will open the door to improve the optical storage capacity steadily to meet the need of the developing big data center.

Quantum break-time of de Sitter

NASA Astrophysics Data System (ADS)

Dvali, Gia; Gómez, César; Zell, Sebastian

2017-06-01

The quantum break-time of a system is the time-scale after which its true quantum evolution departs from the classical mean field evolution. For capturing it, a quantum resolution of the classical background—e.g., in terms of a coherent state—is required. In this paper, we first consider a simple scalar model with anharmonic oscillations and derive its quantum break-time. Next, following [1], we apply these ideas to de Sitter space. We formulate a simple model of a spin-2 field, which for some time reproduces the de Sitter metric and simultaneously allows for its well-defined representation as quantum coherent state of gravitons. The mean occupation number N of background gravitons turns out to be equal to the de Sitter horizon area in Planck units, while their frequency is given by the de Sitter Hubble parameter. In the semi-classical limit, we show that the model reproduces all the known properties of de Sitter, such as the redshift of probe particles and thermal Gibbons-Hawking radiation, all in the language of quantum S-matrix scatterings and decays of coherent state gravitons. Most importantly, this framework allows to capture the 1/N-effects to which the usual semi-classical treatment is blind. They violate the de Sitter symmetry and lead to a finite quantum break-time of the de Sitter state equal to the de Sitter radius times N. We also point out that the quantum-break time is inversely proportional to the number of particle species in the theory. Thus, the quantum break-time imposes the following consistency condition: older and species-richer universes must have smaller cosmological constants. For the maximal, phenomenologically acceptable number of species, the observed cosmological constant would saturate this bound if our Universe were 10100 years old in its entire classical history.

A two-dimensional analysis of the sensitivity of a pulse first break to wave speed contrast on a scale below the resolution length of ray tomography.

PubMed

Willey, Carson L; Simonetti, Francesco

2016-06-01

Mapping the speed of mechanical waves traveling inside a medium is a topic of great interest across many fields from geoscience to medical diagnostics. Much work has been done to characterize the fidelity with which the geometrical features of the medium can be reconstructed and multiple resolution criteria have been proposed depending on the wave-matter interaction model used to decode the wave speed map from scattering measurements. However, these criteria do not define the accuracy with which the wave speed values can be reconstructed. Using two-dimensional simulations, it is shown that the first-arrival traveltime predicted by ray theory can be an accurate representation of the arrival of a pulse first break even in the presence of diffraction and other phenomena that are not accounted for by ray theory. As a result, ray-based tomographic inversions can yield accurate wave speed estimations also when the size of a sound speed anomaly is smaller than the resolution length of the inversion method provided that traveltimes are estimated from the signal first break. This increased sensitivity however renders the inversion more susceptible to noise since the amplitude of the signal around the first break is typically low especially when three-dimensional anomalies are considered.

Pushing the physical limits of spectroscopic imaging for new biology and better medicine (Conference Presentation)

NASA Astrophysics Data System (ADS)

Cheng, Ji-Xin

2017-02-01

In vivo molecular spectroscopic imaging is not a simple addition of a spectrometer to a microscope. Innovations are needed to break the physical limits in sensitivity, depth, speed and resolution perspectives. I will present our most recent advances in modality development, biological application, and clinical translation. My talk will focus on the development of mid-infrared photothermal microscope for depth-resolved vibrational imaging of living cells (Science Advances, in press), the discovery of a metabolic signature in cancer stem cells by hyperspectral stimulated Raman scattering imaging (Cell Stem Cell, in press), and the development of an intravascular vibrational photoacoustic catheter for label-free sensing of lipid laden plaques (Scientific Report 2016, 6:25236).

Multiple-aperture optical design for micro-level cameras using 3D-printing method

NASA Astrophysics Data System (ADS)

Peng, Wei-Jei; Hsu, Wei-Yao; Cheng, Yuan-Chieh; Lin, Wen-Lung; Yu, Zong-Ru; Chou, Hsiao-Yu; Chen, Fong-Zhi; Fu, Chien-Chung; Wu, Chong-Syuan; Huang, Chao-Tsung

2018-02-01

The design of the ultra miniaturized camera using 3D-printing technology directly printed on to the complementary metal-oxide semiconductor (CMOS) imaging sensor is presented in this paper. The 3D printed micro-optics is manufactured using the femtosecond two-photon direct laser writing, and the figure error which could achieve submicron accuracy is suitable for the optical system. Because the size of the micro-level camera is approximately several hundreds of micrometers, the resolution is reduced much and highly limited by the Nyquist frequency of the pixel pitch. For improving the reduced resolution, one single-lens can be replaced by multiple-aperture lenses with dissimilar field of view (FOV), and then stitching sub-images with different FOV can achieve a high resolution within the central region of the image. The reason is that the angular resolution of the lens with smaller FOV is higher than that with larger FOV, and then the angular resolution of the central area can be several times than that of the outer area after stitching. For the same image circle, the image quality of the central area of the multi-lens system is significantly superior to that of a single-lens. The foveated image using stitching FOV breaks the limitation of the resolution for the ultra miniaturized imaging system, and then it can be applied such as biomedical endoscopy, optical sensing, and machine vision, et al. In this study, the ultra miniaturized camera with multi-aperture optics is designed and simulated for the optimum optical performance.

Development of the Advanced Energetic Pair Telescope (AdEPT) for Medium-Energy Gamma-Ray Astronomy

NASA Technical Reports Server (NTRS)

Hunter, Stanley D.; Bloser, Peter F.; Dion, Michael P.; McConnell, Mark L.; deNolfo, Georgia A.; Son, Seunghee; Ryan, James M.; Stecker, Floyd W.

2011-01-01

Progress in high-energy gamma-ray science has been dramatic since the launch of INTEGRAL, AGILE and FERMI. These instruments, however, are not optimized for observations in the medium-energy (approx.0.3< E(sub gamma)< approx.200 MeV) regime where many astrophysical objects exhibit unique, transitory behavior, such as spectral breaks, bursts, and flares. We outline some of the major science goals of a medium-energy mission. These science goals are best achieved with a combination of two telescopes, a Compton telescope and a pair telescope, optimized to provide significant improvements in angular resolution and sensitivity. In this paper we describe the design of the Advanced Energetic Pair Telescope (AdEPT) based on the Three-Dimensional Track Imager (3-DTI) detector. This technology achieves excellent, medium-energy sensitivity, angular resolution near the kinematic limit, and gamma-ray polarization sensitivity, by high resolution 3-D electron tracking. We describe the performance of a 30x30x30 cm3 prototype of the AdEPT instrument.

Sparse synthetic aperture with Fresnel elements (S-SAFE) using digital incoherent holograms

PubMed Central

Kashter, Yuval; Rivenson, Yair; Stern, Adrian; Rosen, Joseph

2015-01-01

Creating a large-scale synthetic aperture makes it possible to break the resolution boundaries dictated by the wave nature of light of common optical systems. However, their implementation is challenging, since the generation of a large size continuous mosaic synthetic aperture composed of many patterns is complicated in terms of both phase matching and time-multiplexing duration. In this study we present an advanced configuration for an incoherent holographic imaging system with super resolution qualities that creates a partial synthetic aperture. The new system, termed sparse synthetic aperture with Fresnel elements (S-SAFE), enables significantly decreasing the number of the recorded elements, and it is free from positional constrains on their location. Additionally, in order to obtain the best image quality we propose an optimal mosaicking structure derived on the basis of physical and numerical considerations, and introduce three reconstruction approaches which are compared and discussed. The super-resolution capabilities of the proposed scheme and its limitations are analyzed, numerically simulated and experimentally demonstrated. PMID:26367947

Interplanetary Magnetic Field Power Spectrum Variations: A VHO Enabled Study

NASA Astrophysics Data System (ADS)

Szabo, A.; Koval, A.; Merka, J.; Narock, T. W.

2010-12-01

The newly reprocessed high time resolution (11/22 vectors/sec) Wind mission interplanetary magnetic field data and the solar wind key parameter search capability of the Virtual Heliospheric Observatory (VHO) affords an opportunity to study magnetic field power spectral density variations as a function of solar wind conditions. In the reprocessed Wind Magnetic Field Investigation (MFI) data, the spin tone and its harmonics are greatly reduced that allows the meaningful fitting of power spectra to the ~2 Hz limit above which digitization noise becomes apparent. The power spectral density is computed and the spectral index is fitted for the MHD and ion inertial regime separately along with the break point between the two for various solar wind conditions . The time periods of fixed solar wind conditions are obtained from VHO searches that greatly simplify the process. The functional dependence of the ion inertial spectral index and break point on solar wind plasma and magnetic field conditions will be discussed.

Maximizing the security of chaotic optical communications.

PubMed

Hou, T T; Yi, L L; Yang, X L; Ke, J X; Hu, Y; Yang, Q; Zhou, P; Hu, W S

2016-10-03

The practical application of chaotic optical communications has been limited by two aspects: the difficulty in concealing the time delay - a critical security parameter in feedback chaotic systems, and the difficulty of significantly enlarging the key space without complicating the implementation. Here we propose an architecture to break the above limits. By introducing a frequency-dependent group delay module with frequency tuning resolution of 1 MHz into the chaotic feedback loop, we demonstrate excellent time delay concealment effect, and an additional huge key space of 10⁴⁸ can be achieved at the same time. The effectiveness is proved by both numerical simulation and experiment. Besides, the proposed scheme is compatible with the existing commercial optical communication systems, thus pave the way for high-speed secure optical communications.

Fabrication and characterization of high-efficiency double-sided blazed x-ray optics.

PubMed

Mohacsi, Istvan; Vartiainen, Ismo; Guizar-Sicairos, Manuel; Karvinen, Petri; Guzenko, Vitaliy A; Müller, Elisabeth; Kewish, Cameron M; Somogyi, Andrea; David, Christian

2016-01-15

The focusing efficiency of conventional diffractive x-ray lenses is fundamentally limited due to their symmetric binary structures and the corresponding symmetry of their focusing and defocusing diffraction orders. Fresnel zone plates with asymmetric structure profiles can break this limitation; yet existing implementations compromise either on resolution, ease of use, or stability. We present a new way for the fabrication of such blazed lenses by patterning two complementary binary Fresnel zone plates on the front and back sides of the same membrane chip to provide a compact, inherently stable, single-chip device. The presented blazed double-sided zone plates with 200 nm smallest half-pitch provide up to 54.7% focusing efficiency at 6.2 keV, which is clearly beyond the value obtainable by their binary counterparts.

Spectroscopic photon localization microscopy: breaking the resolution limit of single molecule localization microscopy (Conference Presentation)

NASA Astrophysics Data System (ADS)

Dong, Biqin; Almassalha, Luay Matthew; Urban, Ben E.; Nguyen, The-Quyen; Khuon, Satya; Chew, Teng-Leong; Backman, Vadim; Sun, Cheng; Zhang, Hao F.

2017-02-01

Distinguishing minute differences in spectroscopic signatures is crucial for revealing the fluorescence heterogeneity among fluorophores to achieve a high molecular specificity. Here we report spectroscopic photon localization microscopy (SPLM), a newly developed far-field spectroscopic imaging technique, to achieve nanoscopic resolution based on the principle of single-molecule localization microscopy while simultaneously uncovering the inherent molecular spectroscopic information associated with each stochastic event (Dong et al., Nature Communications 2016, in press). In SPLM, by using a slit-less monochromator, both the zero-order and the first-order diffractions from a grating were recorded simultaneously by an electron multiplying charge-coupled device to reveal the spatial distribution and the associated emission spectra of individual stochastic radiation events, respectively. As a result, the origins of photon emissions from different molecules can be identified according to their spectral differences with sub-nm spectral resolution, even when the molecules are within close proximity. With the newly developed algorithms including background subtraction and spectral overlap unmixing, we established and tested a method which can significantly extend the fundamental spatial resolution limit of single molecule localization microscopy by molecular discrimination through spectral regression. Taking advantage of this unique capability, we demonstrated improvement in spatial resolution of PALM/STORM up to ten fold with selected fluorophores. This technique can be readily adopted by other research groups to greatly enhance the optical resolution of single molecule localization microscopy without the need to modify their existing staining methods and protocols. This new resolving capability can potentially provide new insights into biological phenomena and enable significant research progress to be made in the life sciences.

Comparison of vacuum rise time, vacuum limit accuracy, and occlusion break surge of 3 new phacoemulsification systems.

PubMed

Han, Young Keun; Miller, Kevin M

2009-08-01

To compare vacuum rise time, vacuum limit accuracy, and occlusion break surge of 3 new phacoemulsification machines. Jules Stein Eye Institute and Department of Ophthalmology, David Geffen School of Medicine at UCLA, Los Angeles, California, USA. The vacuum rise time under normal and enhanced aspiration modes, vacuum limit accuracy, and occlusion break surge of the Infiniti Vision System, Stellaris Vision Enhancement System, and WhiteStar Signature Phacoemulsification System were tested. Vacuum rise time and limit accuracy were measured at limit settings of 400 mm Hg and 600 mm Hg. Surge area was recorded at vacuum limit settings of 200 mm Hg, 300 mm Hg, 400 mm Hg, and 500 mm Hg. The Infiniti had the fastest vacuum rise times under normal and enhanced aspiration modes. At 4 seconds, the vacuum limit accuracy was greatest with the Infiniti at the 400 mm Hg limit and the Signature at the 600 mm Hg limit. The Stellaris did not reach either vacuum target. The Infiniti performed better than the other 2 machines during testing of occlusion break surge at all vacuum limit settings above 200 mm Hg. Under controlled laboratory test conditions, the Infiniti had the fastest vacuum rise time, greatest vacuum limit accuracy at 400 mm Hg, and least occlusion break surge. These results can be explained by the lower compliance of the Infiniti system.

Sea surface temperature of the coastal zones of France. Heat Capacity Mapping Mission (HCMM)

NASA Technical Reports Server (NTRS)

Deschamps, P. Y.; Frouin, R.; Cassanet, G.; Verger, F. (Principal Investigator)

1979-01-01

The author has identified the following significant results. HCMM data analysis shows some mesoscale features which were previously expected to occur: summer coastal upwellings in the Gulf of Lions, tidal fronts bordering the English Channel, and cooler surface waters at the continental shelf break. The analysis of the spectral variance density spectra show that the interpretation of the data usually is limited by the HCMM radiometric performance (noise levels) at wavenumbers below 5 km in the oceanic areas; from this analysis it may also be concluded that a decrease of the radiometric noise level down to 0.1 k against an increase of the ground resolution up to 2 km would give a better optimum of the radiometric performances in the oceanic areas. HCMM data appear to be useful for analysis of the sea surface temperature field, particularly in the very coastal area by profiting from the ground resolution of 500 m.

3D wide field-of-view Gabor-domain optical coherence microscopy advancing real-time in-vivo imaging and metrology

NASA Astrophysics Data System (ADS)

Canavesi, Cristina; Cogliati, Andrea; Hayes, Adam; Tankam, Patrice; Santhanam, Anand; Rolland, Jannick P.

2017-02-01

Real-time volumetric high-definition wide-field-of-view in-vivo cellular imaging requires micron-scale resolution in 3D. Compactness of the handheld device and distortion-free images with cellular resolution are also critically required for onsite use in clinical applications. By integrating a custom liquid lens-based microscope and a dual-axis MEMS scanner in a compact handheld probe, Gabor-domain optical coherence microscopy (GD-OCM) breaks the lateral resolution limit of optical coherence tomography through depth, overcoming the tradeoff between numerical aperture and depth of focus, enabling advances in biotechnology. Furthermore, distortion-free imaging with no post-processing is achieved with a compact, lightweight handheld MEMS scanner that obtained a 12-fold reduction in volume and 17-fold reduction in weight over a previous dual-mirror galvanometer-based scanner. Approaching the holy grail of medical imaging - noninvasive real-time imaging with histologic resolution - GD-OCM demonstrates invariant resolution of 2 μm throughout a volume of 1 x 1 x 0.6 mm3, acquired and visualized in less than 2 minutes with parallel processing on graphics processing units. Results on the metrology of manufactured materials and imaging of human tissue with GD-OCM are presented.

Upper limits to the annihilation radiation luminosity of Centaurus A

NASA Technical Reports Server (NTRS)

Gehrels, N.; Cline, T. L.; Paciesas, W. S.; Teegarden, B. J.; Tueller, J.; Dirouchoux, P.; Hameury, J. M.

1983-01-01

A high resolution observation of the active nucleus galaxy Centaurus A (NGC 5128) was made by the GSFC low energy gamma-ray spectrometer (LEGS) during a balloon flight on 1981 November 19. The measured spectrum between 70 and 500 keV is well represented by a power law of the form 1.05 x 10 (-4) (E/100 keV) (-1.59) ph/sq cm/s with no breaks or line features observed. The 98 percent confidence (2 sigma) flux upper limit for a narrow (3 keV) 511-keV positron annihilation line is 9.9 x 10 (-4) ph/sq cm/s. Using this upper limit, the ratio of the narrow-line annihilation radiation luminosity to the integral or = 511 keV luminosity is estimated to be 0.09 (2 sigma upper limit). This is compared with the measured value for our Galactic center in the Fall of 1979 of 0.10 to 0.13, indicating a difference in the emission regions in the nuclei of the two galaxies.

Upper Limits to the Annihilation Radiation Luminosity of Centaurus a

NASA Technical Reports Server (NTRS)

Gehrels, N.; Cline, T. L.; Paciesas, W. S.; Teegarden, B. J.; Tueller, J.; Dirouchoux, P.; Hameury, J. M.

1983-01-01

A high resolution observation of the active nucleus galaxy Centaurus A (NGC 5128) was made by the GSFC low energy gamma-ray spectrometer (LEGS) during a balloon flight on 1981 November 19. The measured spectrum between 70 and 500 keV is well represented by a power law of the form 1.05 x 10 (-4) (E/100 keV) (-1.59) ph/sq cm /s with no breaks or line features observed. The 98% confidence (2 sigma) flux upper limit for a narrow ( 3 keV) 511-keV positron annihilation line is 9.9 x 10 (-4) ph/ sq cm /s. Using this upper limit, the ratio of the narrow-line annihilation radiation luminosity to the integral or = 511 keV luminosity is estimated to be 0.09 (2 sigma upper limit). This is compared with the measured value for our galactic center in the Fall of 1979 of 0.10 to 0.13, indicating a difference in he emission regions in the nuclei of the two galaxies.

λ/26 silver nanodots fabricated by direct laser writing through highly sensitive two-photon photoreduction

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

Cao, Yaoyu; Gu, Min, E-mail: mgu@swin.edu.au

We demonstrated an approach to break the diffraction limit and realise deep-subwavelength two-photon direct laser writing by employing a highly sensitive photoreduction process. The photoreduction photosensitivity increased by at least 4 times while the wavelength of the fabrication laser beam was tuned from 800 nm to 580 nm. The increase of the photosensitivity resulted in improved resolution for the silver dot fabrication. By developing the photoreduction material with adding electron donors, the photosensitivity further increased and enabled the realisation of a single silver dot at 22 nm which is λ/26 for the wavelength of the fabrication laser beam.

Wave Dissipation over Nearshore Beach Morphology: Insights from High-Resolution LIDAR Observations and the SWASH Wave Model

NASA Astrophysics Data System (ADS)

Mulligan, R. P.; Gomes, E.; McNinch, J.; Brodie, K. L.

2016-02-01

Numerical modelling of the nearshore zone can be computationally intensive due to the complexity of wave breaking, and the need for high temporal and spatial resolution. In this study we apply the SWASH non-hydrostatic wave-flow model that phase-resolves the free surface and fluid motions in the water column at high resolution. The model is forced using observed directional energy spectra, and results are compared to wave observations during moderate storm events. Observations are collected outside the surf zone using acoustic wave and currents sensors, and inside the surf zone over a 100 m transect using high-resolution LIDAR measurements of the sea surface from a sensor mounted on a tower on the beach dune at the Field Research Facility in Duck, NC. The model is applied to four cases with different wave conditions and bathymetry, and used to predict the spatial variability in wave breaking, and correlation between energy dissipation and morphologic features. Model results compare well with observations of spectral evolution outside the surf zone, and with the remotely sensed observations of wave transformation inside the surf zone. The results indicate the importance of nearshore bars, rip-channels, and larger features (major scour depression under the pier following large waves from Hurricane Irene) on the location of wave breaking and alongshore variability in wave energy dissipation.

Quantum break-time of de Sitter

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

Dvali, Gia; Gómez, César; Zell, Sebastian, E-mail: georgi.dvali@physik.uni-muenchen.de, E-mail: cesar.gomez@uam.es, E-mail: sebastian.zell@campus.lmu.de

The quantum break-time of a system is the time-scale after which its true quantum evolution departs from the classical mean field evolution. For capturing it, a quantum resolution of the classical background—e.g., in terms of a coherent state—is required. In this paper, we first consider a simple scalar model with anharmonic oscillations and derive its quantum break-time. Next, following [1], we apply these ideas to de Sitter space. We formulate a simple model of a spin-2 field, which for some time reproduces the de Sitter metric and simultaneously allows for its well-defined representation as quantum coherent state of gravitons. Themore » mean occupation number N of background gravitons turns out to be equal to the de Sitter horizon area in Planck units, while their frequency is given by the de Sitter Hubble parameter. In the semi-classical limit, we show that the model reproduces all the known properties of de Sitter, such as the redshift of probe particles and thermal Gibbons-Hawking radiation, all in the language of quantum S -matrix scatterings and decays of coherent state gravitons. Most importantly, this framework allows to capture the 1/ N -effects to which the usual semi-classical treatment is blind. They violate the de Sitter symmetry and lead to a finite quantum break-time of the de Sitter state equal to the de Sitter radius times N . We also point out that the quantum-break time is inversely proportional to the number of particle species in the theory. Thus, the quantum break-time imposes the following consistency condition: older and species-richer universes must have smaller cosmological constants. For the maximal, phenomenologically acceptable number of species, the observed cosmological constant would saturate this bound if our Universe were 10{sup 100} years old in its entire classical history.« less

Wave Breaking Dissipation in Fetch-Limited Seas

NASA Astrophysics Data System (ADS)

Schwendeman, M.; Thomson, J. M.; Gemmrich, J.

2012-12-01

Breaking waves on the ocean surface control wave growth and enhance air-sea interaction, yet field measurements of breaking are limited. A promising technique for field measurements of wave breaking uses the breaking crest length distribution Λ(c), introduced by Phillips (1985). However, calculating dynamic quantities from Λ(c) requires knowledge of the breaking strength parameter, b. Estimates of a b have varied over many orders of magnitude, and recent studies have attempted to model b in terms of sea state, such as wave steepness or saturation. We present comprehensive observations of breaking in fetch-limited conditions from Juan de Fuca Strait, WA. The wave evolution along fetch is explained by an observed energy budget using the radiative transfer equation (RTE), and the evolution is consistent with existing empirical fetch laws. Estimates of Λ(c) increase along fetch and are consistent with directly measured breaking rates. Using novel in situ measures of dissipation, as well as a residual term from the RTE budget, we obtain robust estimates of the wave breaking strength b. Results suggest that b decreases with wave steepness and saturation, in contrast with recent laboratory results (Drazen et al, 2008). This trend is discussed in terms of the fetch evolution and associated broadening of the equilibrium range in the wave spectra.Map of drifter tracks colored by wave height for two days in Juan de Fuca Strait, WA.

The influence of chilling requirement on the southern distribution limit of exotic Russian olive (Elaeagnus angustifolia) in western North America

USGS Publications Warehouse

Guilbault, Kimberly R.; Brown, C.S.; Friedman, J.M.; Shafroth, P.B.

2012-01-01

Russian olive (Elaeagnus angustifolia L.), a Eurasian tree now abundant along rivers in western North America, has an apparent southern distribution limit running through southern California, Arizona, New Mexico and Texas. We used field observations to precisely define this limit in relation to temperature variables. We then investigated whether lack of cold temperatures south of the limit may prevent the accumulation of sufficient chilling, inhibiting dormancy loss of seeds and buds. We found that Russian olive occurrence was more strongly associated with low winter temperatures than with high summer temperatures, and results of controlled seed germination and vegetative bud-break experiments suggest that the chilling requirements for germination and bud-break are partly responsible for the southern range limit. Both seed germination proportion and germination time decreased under conditions simulating those south of the range limit. Similarly, percentage bud break decreased when chilling dropped below values typical of the range limit. In 17–65% of the years from 1980 to 2000, the chilling accumulated at a site near the range limit (El Paso, TX) would lead to a 10% or more decrease in bud-break. The potential decline in growth could have large fitness consequences for Russian olive. If climate change exhibits a warming trend, our results suggest the chilling requirement for bud-break of Russian olive trees will not be met in some years and its southern range limit may retreat northward.

Schemes of detecting nuclear spin correlations by dynamical decoupling based quantum sensing

NASA Astrophysics Data System (ADS)

Ma, Wen-Long Ma; Liu, Ren-Bao

Single-molecule sensitivity of nuclear magnetic resonance (NMR) and angstrom resolution of magnetic resonance imaging (MRI) are the highest challenges in magnetic microscopy. Recent development in dynamical decoupling (DD) enhanced diamond quantum sensing has enabled NMR of single nuclear spins and nanoscale NMR. Similar to conventional NMR and MRI, current DD-based quantum sensing utilizes the frequency fingerprints of target nuclear spins. Such schemes, however, cannot resolve different nuclear spins that have the same noise frequency or differentiate different types of correlations in nuclear spin clusters. Here we show that the first limitation can be overcome by using wavefunction fingerprints of target nuclear spins, which is much more sensitive than the ''frequency fingerprints'' to weak hyperfine interaction between the targets and a sensor, while the second one can be overcome by a new design of two-dimensional DD sequences composed of two sets of periodic DD sequences with different periods, which can be independently set to match two different transition frequencies. Our schemes not only offer an approach to breaking the resolution limit set by ''frequency gradients'' in conventional MRI, but also provide a standard approach to correlation spectroscopy for single-molecule NMR.

Model Building to Facilitate Understanding of Holliday Junction and Heteroduplex Formation, and Holliday Junction Resolution

ERIC Educational Resources Information Center

Selvarajah, Geeta; Selvarajah, Susila

2016-01-01

Students frequently expressed difficulty in understanding the molecular mechanisms involved in chromosomal recombination. Therefore, we explored alternative methods for presenting the two concepts of the double-strand break model: Holliday junction and heteroduplex formation, and Holliday junction resolution. In addition to a lecture and…

Fermion-number violation in regularizations that preserve fermion-number symmetry

NASA Astrophysics Data System (ADS)

Golterman, Maarten; Shamir, Yigal

2003-01-01

There exist both continuum and lattice regularizations of gauge theories with fermions which preserve chiral U(1) invariance (“fermion number”). Such regularizations necessarily break gauge invariance but, in a covariant gauge, one recovers gauge invariance to all orders in perturbation theory by including suitable counterterms. At the nonperturbative level, an apparent conflict then arises between the chiral U(1) symmetry of the regularized theory and the existence of ’t Hooft vertices in the renormalized theory. The only possible resolution of the paradox is that the chiral U(1) symmetry is broken spontaneously in the enlarged Hilbert space of the covariantly gauge-fixed theory. The corresponding Goldstone pole is unphysical. The theory must therefore be defined by introducing a small fermion-mass term that breaks explicitly the chiral U(1) invariance and is sent to zero after the infinite-volume limit has been taken. Using this careful definition (and a lattice regularization) for the calculation of correlation functions in the one-instanton sector, we show that the ’t Hooft vertices are recovered as expected.

A resolution of the inclusive flavor-breaking τ |Vus| puzzle

NASA Astrophysics Data System (ADS)

Hudspith, Renwick J.; Lewis, Randy; Maltman, Kim; Zanotti, James

2018-06-01

We revisit the puzzle of |Vus | values obtained from the conventional implementation of hadronic-τ- decay-based flavor-breaking finite-energy sum rules lying > 3 σ below the expectations of three-family unitarity. Significant unphysical dependences of |Vus | on the choice of weight, w, and upper limit, s0, of the experimental spectral integrals entering the analysis are confirmed, and a breakdown of assumptions made in estimating higher dimension, D > 4, OPE contributions identified as the main source of these problems. A combination of continuum and lattice results is shown to suggest a new implementation of the flavor-breaking sum rule approach in which not only |Vus |, but also D > 4 effective condensates, are fit to data. Lattice results are also used to clarify how to reliably treat the slowly converging D = 2 OPE series. The new sum rule implementation is shown to cure the problems of the unphysical w- and s0-dependence of |Vus | and to produce results ∼0.0020 higher than those of the conventional implementation employing the same data. With B-factory input, and using, in addition, dispersively constrained results for the Kπ branching fractions, we find |Vus | = 0.2231(27)exp(4)th, in excellent agreement with the result from Kℓ3, and compatible within errors with the expectations of three-family unitarity, thus resolving the long-standing inclusive τ |Vus | puzzle.

A wide field-of-view microscope based on holographic focus grid

NASA Astrophysics Data System (ADS)

Wu, Jigang; Cui, Xiquan; Zheng, Guoan; Lee, Lap Man; Yang, Changhuei

2010-02-01

We have developed a novel microscope technique that can achieve wide field-of-view (FOV) imaging and yet possess resolution that is comparable to conventional microscope. The principle of wide FOV microscope system breaks the link between resolution and FOV magnitude of traditional microscopes. Furthermore, by eliminating bulky optical elements from its design and utilizing holographic optical elements, the wide FOV microscope system is more cost-effective. In our system, a hologram was made to focus incoming collimated beam into a focus grid. The sample is put in the focal plane and the transmissions of the focuses are detected by an imaging sensor. By scanning the incident angle of the incoming beam, the focus grid will scan across the sample and the time-varying transmission can be detected. We can then reconstruct the transmission image of the sample. The resolution of microscopic image is limited by the size of the focus formed by the hologram. The scanning area of each focus spot is determined by the separation of the focus spots and can be made small for fast imaging speed. We have fabricated a prototype system with a 2.4-mm FOV and 1-μm resolution. The prototype system was used to image onion skin cells for a demonstration. The preliminary experiments prove the feasibility of the wide FOV microscope technique, and the possibility of a wider FOV system with better resolution.

Quantifying high resolution transitional breaks in plant and mammal distributions at regional extent and their association with climate, topography and geology.

PubMed

Di Virgilio, Giovanni; Laffan, Shawn W; Ebach, Malte C

2013-01-01

We quantify spatial turnover in communities of 1939 plant and 59 mammal species at 2.5 km resolution across a topographically heterogeneous region in south-eastern Australia to identify distributional breaks and low turnover zones where multiple species distributions overlap. Environmental turnover is measured to determine how climate, topography and geology influence biotic turnover differently across a variety of biogeographic breaks and overlaps. We identify the genera driving turnover and confirm the versatility of this approach across spatial scales and locations. Directional moving window analyses, rotated through 360°, were used to measure spatial turnover variation in different directions between gridded cells containing georeferenced plant and mammal occurrences and environmental variables. Generalised linear models were used to compare taxic turnover results with equivalent analyses for geology, regolith weathering, elevation, slope, solar radiation, annual precipitation and annual mean temperature, both uniformly across the entire study area and by stratifying it into zones of high and low turnover. Identified breaks and transitions were compared to a conservation bioregionalisation framework widely used in Australia. Detailed delineations of plant and mammal turnover zones with gradational boundaries denoted subtle variation in species assemblages. Turnover patterns often diverged from bioregion boundaries, though plant turnover adhered most closely. A prominent break zone contained either comparable or greater numbers of unique genera than adjacent overlaps, but these were concentrated in a small subsection relatively under-protected by conservation reserves. The environmental correlates of biotic turnover varied for different turnover zones in different subsections of the study area. Topography and temperature showed much stronger relationships with plant turnover in a topographically complex overlap, relative to a lowland overlap where weathering was most predictive. This method can quantify transitional turnover patterns from small to broad extents, at different resolutions for any location, and complements broad-scale bioregionalisation schemes in conservation planning.

What the success of brain imaging implies about the neural code.

PubMed

Guest, Olivia; Love, Bradley C

2017-01-19

The success of fMRI places constraints on the nature of the neural code. The fact that researchers can infer similarities between neural representations, despite fMRI's limitations, implies that certain neural coding schemes are more likely than others. For fMRI to succeed given its low temporal and spatial resolution, the neural code must be smooth at the voxel and functional level such that similar stimuli engender similar internal representations. Through proof and simulation, we determine which coding schemes are plausible given both fMRI's successes and its limitations in measuring neural activity. Deep neural network approaches, which have been forwarded as computational accounts of the ventral stream, are consistent with the success of fMRI, though functional smoothness breaks down in the later network layers. These results have implications for the nature of the neural code and ventral stream, as well as what can be successfully investigated with fMRI.

Translational Symmetry Breaking and Gapping of Heavy-Quasiparticle Pocket in URu2Si2

PubMed Central

Yoshida, Rikiya; Tsubota, Koji; Ishiga, Toshihiko; Sunagawa, Masanori; Sonoyama, Jyunki; Aoki, Dai; Flouquet, Jacques; Wakita, Takanori; Muraoka, Yuji; Yokoya, Takayoshi

2013-01-01

URu2Si2 is a uranium compound that exhibits a so-called ‘hidden-order’ transition at ~17.5 K. However, the order parameter of this second-order transition as well as many of its microscopic properties remain unclarified despite considerable research. One of the key questions in this regard concerns the type of spontaneous symmetry breaking occurring at the transition; although rotational symmetry breaking has been detected, it is not clear whether another type of symmetry breaking also occurs. Another key question concerns the property of Fermi-surface gapping in the momentum space. Here we address these key questions by a momentum-dependent observation of electronic states at the transition employing ultrahigh-resolution three-dimensional angle-resolved photoemission spectroscopy. Our results provide compelling evidence of the spontaneous breaking of the lattice's translational symmetry and particle-hole asymmetric gapping of a heavy quasiparticle pocket at the transition. PMID:24084937

Some inconvenient truths about biosignatures involving two chemical species on Earth-like exoplanets.

PubMed

Rein, Hanno; Fujii, Yuka; Spiegel, David S

2014-05-13

The detection of strong thermochemical disequilibrium in the atmosphere of an extrasolar planet is thought to be a potential biosignature. In this article we present a previously unidentified kind of false positive that can mimic a disequilibrium or any other biosignature that involves two chemical species. We consider a scenario where the exoplanet hosts a moon that has its own atmosphere and neither of the atmospheres is in chemical disequilibrium. Our results show that the integrated spectrum of the planet and the moon closely resembles that of a single object in strong chemical disequilibrium. We derive a firm limit on the maximum spectral resolution that can be obtained for both directly imaged and transiting planets. The spectral resolution of even idealized space-based spectrographs that might be achievable in the next several decades is in general insufficient to break the degeneracy. Both chemical species can only be definitively confirmed in the same object if absorption features of both chemicals can be unambiguously identified and their combined depth exceeds 100%.

Heavy ion-induced lesions in DNA: A theoretical model for the initial induction of DNA strand breaks and chromatin breaks

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

Schmidt, J.B.

1993-01-01

A theoretical model has been developed and used to calculate yields and spatial distributions of DNA strand breaks resulting from the interactions of heavy ions with chromatin in aqueous systems. The three dimensional spatial distribution of ionizing events has been modeled for charged particles as a function of charge and velocity. Chromatin has been modeled as a 30 nm diameter solenoid of nucleosomal DNA. The Monte Carlo methods used by Chatterjee et al. have been applied to DNA in a chromatin conformation. Refinements to their methods include: a combined treatment of primary and low energy (<2 keV) secondary electron interactions,more » an improved low energy delta ray model, and the combined simulation of direct energy deposition on the DNA and attack by diffusing hydroxyl radicals. Individual particle tracks are treated independently, which is assumed to be applicable to low fluence irradiations in which multiple particle effects are negligible. Single strand break cross section [open quotes]hooks[close quotes] seen in experiments at very high LET appear to be due to the collapsing radial extent of the track, as predicted in the [open quotes]deep sieve[close quotes] hypothesis proposed by Tobias et al. Spatial distributions of lesions produced by particles have been found to depend on chromatin structure. In the future, heavy ions may be used as a tool to probe the organization of DNA in chromatin. A Neyman A-binomial variation of the [open quotes]cluster model[close quotes] for the distribution of chromatin breaks per irradiated cell has been theoretically tested. The model includes a treatment of the chromatin fragment detection technique's resolution, which places a limitation on the minimum size of fragments which can be detected. The model appears to fit some of the experimental data reasonably well. However, further experimental and theoretical refinements are desirable.« less

78 FR 76757 - Regulatory Guidance on Hours of Service of Drivers Rest Break Requirement; Drivers Who Become...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-12-19

... days as ``short haul'' drivers exempt from the break rule, but who occasionally exceed the short haul distance or time limits. Such drivers are then subject to the break requirement and must prepare a record-of-duty-status (RODS) for the day. The intent of the break rule would be satisfied if drivers in...

High count-rate study of two TES x-ray microcalorimeters with different transition temperatures

NASA Astrophysics Data System (ADS)

Lee, Sang-Jun; Adams, Joseph S.; Bandler, Simon R.; Betancourt-Martinez, Gabriele L.; Chervenak, James A.; Eckart, Megan E.; Finkbeiner, Fred M.; Kelley, Richard L.; Kilbourne, Caroline A.; Porter, Frederick S.; Sadleir, John E.; Smith, Stephen J.; Wassell, Edward J.

2017-10-01

We have developed transition-edge sensor (TES) microcalorimeter arrays with high count-rate capability and high energy resolution to carry out x-ray imaging spectroscopy observations of various astronomical sources and the Sun. We have studied the dependence of the energy resolution and throughput (fraction of processed pulses) on the count rate for such microcalorimeters with two different transition temperatures (T c). Devices with both transition temperatures were fabricated within a single microcalorimeter array directly on top of a solid substrate where the thermal conductance of the microcalorimeter is dependent upon the thermal boundary resistance between the TES sensor and the dielectric substrate beneath. Because the thermal boundary resistance is highly temperature dependent, the two types of device with different T cs had very different thermal decay times, approximately one order of magnitude different. In our earlier report, we achieved energy resolutions of 1.6 and 2.3 eV at 6 keV from lower and higher T c devices, respectively, using a standard analysis method based on optimal filtering in the low flux limit. We have now measured the same devices at elevated x-ray fluxes ranging from 50 Hz to 1000 Hz per pixel. In the high flux limit, however, the standard optimal filtering scheme nearly breaks down because of x-ray pile-up. To achieve the highest possible energy resolution for a fixed throughput, we have developed an analysis scheme based on the so-called event grade method. Using the new analysis scheme, we achieved 5.0 eV FWHM with 96% throughput for 6 keV x-rays of 1025 Hz per pixel with the higher T c (faster) device, and 5.8 eV FWHM with 97% throughput with the lower T c (slower) device at 722 Hz.

Probability function of breaking-limited surface elevation. [wind generated waves of ocean

NASA Technical Reports Server (NTRS)

Tung, C. C.; Huang, N. E.; Yuan, Y.; Long, S. R.

1989-01-01

The effect of wave breaking on the probability function of surface elevation is examined. The surface elevation limited by wave breaking zeta sub b(t) is first related to the original wave elevation zeta(t) and its second derivative. An approximate, second-order, nonlinear, non-Gaussian model for zeta(t) of arbitrary but moderate bandwidth is presented, and an expression for the probability density function zeta sub b(t) is derived. The results show clearly that the effect of wave breaking on the probability density function of surface elevation is to introduce a secondary hump on the positive side of the probability density function, a phenomenon also observed in wind wave tank experiments.

Hybrid Plasmonic Microring Nano-Ruler.

PubMed

Du, Jing; Wang, Jian

2018-06-15

Surface plasmonic polariton (SPP) has attracted increasing interest for its ability of confining light in the subwavelength scale and breaking the diffraction limit. Recently, there have appeared several important developments of SPP applied in plasmon rulers, waveguides and resonators. By combing these concepts we present a novel hybrid plasmonic microring nano-ruler relying on the sensitive hybrid mode property and the microring resonator structure. The designed nano-ruler can measure distance in nanoscale resolution and offer adjustable sensitivity, which exceeds 14.8 as the distance is less than 5 nm by recording the transmission spectra and outstrips 200 dB/nm by observing the shift of output intensity. These demonstrations suggest that hybrid plasmonic microring nano-ruler could be a promising candidate enabling high-resoluation measurement.

Industrial X-Ray Imaging

NASA Technical Reports Server (NTRS)

1997-01-01

In 1990, Lewis Research Center jointly sponsored a conference with the U.S. Air Force Wright Laboratory focused on high speed imaging. This conference, and early funding by Lewis Research Center, helped to spur work by Silicon Mountain Design, Inc. to break the performance barriers of imaging speed, resolution, and sensitivity through innovative technology. Later, under a Small Business Innovation Research contract with the Jet Propulsion Laboratory, the company designed a real-time image enhancing camera that yields superb, high quality images in 1/30th of a second while limiting distortion. The result is a rapidly available, enhanced image showing significantly greater detail compared to image processing executed on digital computers. Current applications include radiographic and pathology-based medicine, industrial imaging, x-ray inspection devices, and automated semiconductor inspection equipment.

Creating Directed Double-strand Breaks with the Ref Protein: A Novel Rec A-Dependent Nuclease from Bacteriophage P1

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

Gruenig, Marielle C.; Lu, Duo; Won, Sang Joon

2012-03-16

The bacteriophage P1-encoded Ref protein enhances RecA-dependent recombination in vivo by an unknown mechanism. We demonstrate that Ref is a new type of enzyme; that is, a RecA-dependent nuclease. Ref binds to ss- and dsDNA but does not cleave any DNA substrate until RecA protein and ATP are added to form RecA nucleoprotein filaments. Ref cleaves only where RecA protein is bound. RecA functions as a co-nuclease in the Ref/RecA system. Ref nuclease activity can be limited to the targeted strands of short RecA-containing D-loops. The result is a uniquely programmable endonuclease activity, producing targeted double-strand breaks at any chosenmore » DNA sequence in an oligonucleotide-directed fashion. We present evidence indicating that cleavage occurs in the RecA filament groove. The structure of the Ref protein has been determined to 1.4 {angstrom} resolution. The core structure, consisting of residues 77-186, consists of a central 2-stranded {beta}-hairpin that is sandwiched between several {alpha}-helical and extended loop elements. The N-terminal 76 amino acid residues are disordered; this flexible region is required for optimal activity. The overall structure of Ref, including several putative active site histidine residues, defines a new subclass of HNH-family nucleases. We propose that enhancement of recombination by Ref reflects the introduction of directed, recombinogenic double-strand breaks.« less

Two-stage perceptual learning to break visual crowding.

PubMed

Zhu, Ziyun; Fan, Zhenzhi; Fang, Fang

2016-01-01

When a target is presented with nearby flankers in the peripheral visual field, it becomes harder to identify, which is referred to as crowding. Crowding sets a fundamental limit of object recognition in peripheral vision, preventing us from fully appreciating cluttered visual scenes. We trained adult human subjects on a crowded orientation discrimination task and investigated whether crowding could be completely eliminated by training. We discovered a two-stage learning process with this training task. In the early stage, when the target and flankers were separated beyond a certain distance, subjects acquired a relatively general ability to break crowding, as evidenced by the fact that the breaking of crowding could transfer to another crowded orientation, even a crowded motion stimulus, although the transfer to the opposite visual hemi-field was weak. In the late stage, like many classical perceptual learning effects, subjects' performance gradually improved and showed specificity to the trained orientation. We also found that, when the target and flankers were spaced too finely, training could only reduce, rather than completely eliminate, the crowding effect. This two-stage learning process illustrates a learning strategy for our brain to deal with the notoriously difficult problem of identifying peripheral objects in clutter. The brain first learned to solve the "easy and general" part of the problem (i.e., improving the processing resolution and segmenting the target and flankers) and then tackle the "difficult and specific" part (i.e., refining the representation of the target).

Wave breaking induced surface wakes and jets observed during a bora event

NASA Astrophysics Data System (ADS)

Jiang, Qingfang; Doyle, James D.

2005-09-01

An observational and modeling study of a bora event that occurred during the field phase of the Mesoscale Alpine Programme is presented. Research aircraft in-situ measurements and airborne remote-sensing observations indicate the presence of strong low-level wave breaking and alternating surface wakes and jets along the Croatian coastline over the Adriatic Sea. The observed features are well captured by a high-resolution COAMPS simulation. Analysis of the observations and modeling results indicate that the long-extending wakes above the boundary layer are induced by dissipation associated with the low-level wave breaking, which locally tends to accelerate the boundary layer flow beneath the breaking. Farther downstream of the high peaks, a hydraulic jump occurs in the boundary layer, which creates surface wakes. Downstream of lower-terrain (passes), the boundary layer flow stays strong, resembling supercritical flow.

Beyond the resolution limit: subpixel resolution in animals and now in silicon

NASA Astrophysics Data System (ADS)

Wilcox, M. J.

2007-09-01

Automatic acquisition of aerial threats at thousands of kilometers distance requires high sensitivity to small differences in contrast and high optical quality for subpixel resolution, since targets occupy much less surface area than a single pixel. Targets travel at high speed and break up in the re-entry phase. Target/decoy discrimination at the earliest possible time is imperative. Real time performance requires a multifaceted approach with hyperspectral imaging and analog processing allowing feature extraction in real time. Hyperacuity Systems has developed a prototype chip capable of nonlinear increase in resolution or subpixel resolution far beyond either pixel size or spacing. Performance increase is due to a biomimetic implementation of animal retinas. Photosensitivity is not homogeneous across the sensor surface, allowing pixel parsing. It is remarkably simple to provide this profile to detectors and we showed at least three ways to do so. Individual photoreceptors have a Gaussian sensitivity profile and this nonlinear profile can be exploited to extract high-resolution. Adaptive, analog circuitry provides contrast enhancement, dynamic range setting with offset and gain control. Pixels are processed in parallel within modular elements called cartridges like photo-receptor inputs in fly eyes. These modular elements are connected by a novel function for a cell matrix known as L4. The system is exquisitely sensitive to small target motion and operates with a robust signal under degraded viewing conditions, allowing detection of targets smaller than a single pixel or at greater distance. Therefore, not only is instantaneous feature extraction possible but also subpixel resolution. Analog circuitry increases processing speed with more accurate motion specification for target tracking and identification.

Molecular Switch for Sub-Diffraction Laser Lithography by Photoenol Intermediate-State Cis-Trans Isomerization.

PubMed

Mueller, Patrick; Zieger, Markus M; Richter, Benjamin; Quick, Alexander S; Fischer, Joachim; Mueller, Jonathan B; Zhou, Lu; Nienhaus, Gerd Ulrich; Bastmeyer, Martin; Barner-Kowollik, Christopher; Wegener, Martin

2017-06-27

Recent developments in stimulated-emission depletion (STED) microscopy have led to a step change in the achievable resolution and allowed breaking the diffraction limit by large factors. The core principle is based on a reversible molecular switch, allowing for light-triggered activation and deactivation in combination with a laser focus that incorporates a point or line of zero intensity. In the past years, the concept has been transferred from microscopy to maskless laser lithography, namely direct laser writing (DLW), in order to overcome the diffraction limit for optical lithography. Herein, we propose and experimentally introduce a system that realizes such a molecular switch for lithography. Specifically, the population of intermediate-state photoenol isomers of α-methyl benzaldehydes generated by two-photon absorption at 700 nm fundamental wavelength can be reversibly depleted by simultaneous irradiation at 440 nm, suppressing the subsequent Diels-Alder cycloaddition reaction which constitutes the chemical core of the writing process. We demonstrate the potential of the proposed mechanism for STED-inspired DLW by covalently functionalizing the surface of glass substrates via the photoenol-driven STED-inspired process exploiting reversible photoenol activation with a polymerization initiator. Subsequently, macromolecules are grown from the functionalized areas and the spatially coded glass slides are characterized by atomic-force microscopy. Our approach allows lines with a full-width-at-half-maximum of down to 60 nm and line gratings with a lateral resolution of 100 nm to be written, both surpassing the diffraction limit.

A swath across the great divide: Kelp forests across the Samalga Pass biogeographic break

USGS Publications Warehouse

Konar, Brenda H.; Edwards, Matthew S.; Bland, Aaron; Metzger, Jacob; Ravelo, Alexandra; Traiger, Sarah; Weitzman, Ben P.

2017-01-01

Biogeographic breaks are often described as locations where a large number of species reach their geographic range limits. Samalga Pass, in the eastern Aleutian Archipelago, is a known biogeographic break for the spatial distribution of several species of offshore-pelagic communities, including numerous species of cold-water corals, zooplankton, fish, marine mammals, and seabirds. However, it remains unclear whether Samalga Pass also serves as a biogeographic break for nearshore benthic communities. The occurrence of biogeographic breaks across multiple habitats has not often been described. In this study, we examined if the biogeographic break for offshore-pelagic communities applies to nearshore kelp forests. To examine whether Samalga Pass serves as a biogeographic break for kelp forest communities, this study compared abundance, biomass and percent bottom cover of species associated with kelp forests on either side of the pass. We observed marked differences in kelp forest community structure, with some species reaching their geographic range limits on the opposing sides of the pass. In particular, the habitat-forming kelp Nereocystis luetkeana, and the predatory sea stars Pycnopodia helianthoides and Orthasterias koehleri all occurred on the eastern side of Samalga Pass but were not observed west of the pass. In contrast, the sea star Leptasterias camtschatica dispar was observed only on the western side of the pass. We also observed differences in overall abundance and biomass of numerous associated fish, invertebrate and macroalgal species on opposing sides of the pass. We conclude that Samalga Pass is important biogeographic break for kelp forest communities in the Aleutian Archipelago and may demark the geographic range limits of several ecologically important species.

Far-from-equilibrium bidirectional transport system with constrained entrances competing for pool of limited resources

NASA Astrophysics Data System (ADS)

Verma, Atul Kumar; Sharma, Natasha; Gupta, Arvind Kumar

2018-02-01

Motivated by the wide occurrence of limited resources in many real-life systems, we investigate two-lane totally asymmetric simple exclusion process with constrained entrances under finite supply of particles. We analyze the system within the framework of mean-field theory and examine various complex phenomena, including phase separation, phase transition, and symmetry breaking. Based on the theoretical analysis, we analytically derive the phase boundaries for various symmetric as well as asymmetric phases. It has been observed that the symmetry-breaking phenomenon initiates even for very small number of particles in the system. The phases with broken symmetry originates as shock-low density phase under limited resources, which is in contrast to the scenario with infinite number of particles. As expected, the symmetry breaking continues to persist even for higher values of system particles. Seven stationary phases are observed, with three of them exhibiting symmetry-breaking phenomena. The critical values of a total number of system particles, beyond which various symmetrical and asymmetrical phases appear and disappear are identified. Theoretical outcomes are supported by extensive Monte Carlo simulations. Finally, the size-scaling effect and symmetry-breaking phenomenon on the simulation results have also been examined based on particle density histograms.

MR-Compatible Integrated Eye Tracking System

DTIC Science & Technology

2016-03-10

SECURITY CLASSIFICATION OF: This instrumentation grant was used to purchase state-of-the-art, high-resolution video eye tracker that can be used to...P.O. Box 12211 Research Triangle Park, NC 27709-2211 video eye tracking, eye movments, visual search; camouflage-breaking REPORT DOCUMENTATION PAGE...Report: MR-Compatible Integrated Eye Tracking System Report Title This instrumentation grant was used to purchase state-of-the-art, high-resolution video

Non-Hydrostatic Modelling of Waves and Currents over Subtle Bathymetric Features

NASA Astrophysics Data System (ADS)

Gomes, E.; Mulligan, R. P.; McNinch, J.

2014-12-01

Localized areas with high rates of shoreline erosion on beaches, referred to as erosional hotspots, can occur near clusters of relict shore-oblique sandbars. Wave transformation and wave-driven currents over these morphological features could provide an understanding of the hydrodynamic-morphologic coupling mechanism that connects them to the occurrence of erosional hotspots. To investigate this, we use the non-hydrostatic SWASH model that phase-resolves the free surface and fluid motions throughout the water column, allowing for high resolution of wave propagation and breaking processes. In this study we apply a coupled system of nested models including SWAN over a large domain of the North Carolina shelf with smaller nested SWASH domains in areas of interest to determine the hydrodynamic processes occurring over shore oblique bars. In this presentation we focus on a high resolution grid (10 vertical layers, 10 m horizontal resolution) applied to the Duck region with model validation from acoustic wave and current data, and observations from the Coastal Lidar And Radar Imaging System (CLARIS). By altering the bathymetry input for each model run based on bathymetric surveys and comparing the predicted and observed wave heights and current profiles, the effects of subtle bathymetric perturbations have on wave refraction, wave breaking, surf zone currents and vorticity are investigated. The ability to predict wave breaking and hydrodynamics with a non-hydrostatic model may improve our understanding of surf zone dynamics in relation to morphologic conditions.

Drosha drives the formation of DNA:RNA hybrids around DNA break sites to facilitate DNA repair.

PubMed

Lu, Wei-Ting; Hawley, Ben R; Skalka, George L; Baldock, Robert A; Smith, Ewan M; Bader, Aldo S; Malewicz, Michal; Watts, Felicity Z; Wilczynska, Ania; Bushell, Martin

2018-02-07

The error-free and efficient repair of DNA double-stranded breaks (DSBs) is extremely important for cell survival. RNA has been implicated in the resolution of DNA damage but the mechanism remains poorly understood. Here, we show that miRNA biogenesis enzymes, Drosha and Dicer, control the recruitment of repair factors from multiple pathways to sites of damage. Depletion of Drosha significantly reduces DNA repair by both homologous recombination (HR) and non-homologous end joining (NHEJ). Drosha is required within minutes of break induction, suggesting a central and early role for RNA processing in DNA repair. Sequencing of DNA:RNA hybrids reveals RNA invasion around DNA break sites in a Drosha-dependent manner. Removal of the RNA component of these structures results in impaired repair. These results show how RNA can be a direct and critical mediator of DNA damage repair in human cells.

U(1) mediation of flux supersymmetry breaking

NASA Astrophysics Data System (ADS)

Grimm, Thomas W.; Klemm, Albrecht

2008-10-01

We study the mediation of supersymmetry breaking triggered by background fluxes in Type II string compactifications with Script N = 1 supersymmetry. The mediation arises due to an U(1) vector multiplet coupling to both a hidden supersymmetry breaking flux sector and a visible D-brane sector. The required internal manifolds can be constructed by non-Kähler resolutions of singular Calabi-Yau manifolds. The effective action encoding the U(1) coupling is then determined in terms of the global topological properties of the internal space. We investigate suitable local geometries for the hidden and visible sector in detail. This includes a systematic study of orientifold symmetries of del Pezzo surfaces realized in compact geometries after geometric transition. We construct compact examples admitting the key properties to realize flux supersymmetry breaking and U(1) mediation. Their toric realization allows us to analyze the geometry of curve classes and confirm the topological connection between the hidden and visible sector.

High Resolution Manometry Correlates of Ineffective Esophageal Motility

PubMed Central

Xiao, Yinglian; Kahrilas, Peter J.; Kwasny, Mary J.; Roman, Sabine; Lin, Zhiyue; Nicodème, Frédéric; Lu, Chang; Pandolfino, John E.

2013-01-01

Background There are currently no criteria for ineffective esophageal motility (IEM) and ineffective swallow (IES) in High Resolution Manometry (HRM) and Esophageal Pressure Topography (EPT). Our aims were to utilize HRM metrics to define IEM within the Chicago Classification and to determine the distal contractile integral (DCI) threshold for IES. Methods The EPT of 150 patients with either dysphagia or reflux symptoms were reviewed for the breaks >2 cm in the proximal, middle and distal esophagus in the 20 mmHg isobaric contour (IBC). Peristaltic function in EPT was defined by the Chicago Classification, the corresponding conventional line tracing (CLT) were reviewed separately for IEM and IES. Generalized linear mixed models were used to find thresholds for DCI corresponding to traditionally determined IES and failed swallows. An external validation sample was used to confirm these thresholds. Results In terms of swallow subtypes, IES in CLT were a mixture of normal, weak and failed peristalsis in EPT. A DCI of 450mmHg-s-cm was determined to be optimal in predicting IES. In the validation sample, the threshold of 450 mmHg-s-cm showed strong agreement with CLT determination of IES (positive percent agreement 83%, negative percent agreement 90%) Thirty-three among 42 IEM patients in CLT had large peristaltic breaks, small peristaltic breaks or ‘frequent failed peristalsis’ in EPT; 87.2% (34/39) of patients classified as normal in CLT had proximal IBC-breaks in EPT. the patient level diagnostic agreement between CLT and EPT was good (78.6% positive percent agreement, 63.9% negative percent agreement), with negative agreement increasing to 92.0% if proximal breaks were excluded. Conclusions The manometric correlate of IEM in EPT is a mixture of failed swallows and IBC break in the middle/ distal troughs. A DCI value<450 mmHg-s-cm can be utilized to predict IES previously defined in CLT. IEM can be defined by >5 swallows with weak /failed peristalsis or with a DCI <450 mmHg-s-cm. PMID:22929758

Investigation of skin structures based on infrared wave parameter indirect microscopic imaging

NASA Astrophysics Data System (ADS)

Zhao, Jun; Liu, Xuefeng; Xiong, Jichuan; Zhou, Lijuan

2017-02-01

Detailed imaging and analysis of skin structures are becoming increasingly important in modern healthcare and clinic diagnosis. Nanometer resolution imaging techniques such as SEM and AFM can cause harmful damage to the sample and cannot measure the whole skin structure from the very surface through epidermis, dermis to subcutaneous. Conventional optical microscopy has the highest imaging efficiency, flexibility in onsite applications and lowest cost in manufacturing and usage, but its image resolution is too low to be accepted for biomedical analysis. Infrared parameter indirect microscopic imaging (PIMI) uses an infrared laser as the light source due to its high transmission in skins. The polarization of optical wave through the skin sample was modulated while the variation of the optical field was observed at the imaging plane. The intensity variation curve of each pixel was fitted to extract the near field polarization parameters to form indirect images. During the through-skin light modulation and image retrieving process, the curve fitting removes the blurring scattering from neighboring pixels and keeps only the field variations related to local skin structures. By using the infrared PIMI, we can break the diffraction limit, bring the wide field optical image resolution to sub-200nm, in the meantime of taking advantage of high transmission of infrared waves in skin structures.

Aircraft Observation of Gravity Wave Breaking at the Storm Top and Comparison with High Resolution Cloud Model Simulations and Satellite Images

NASA Astrophysics Data System (ADS)

Wang, P. K.; Cheng, K. Y.; Lindsey, D. T.

2017-12-01

Deep convective clouds play an important role in the transport of momentum, energy, and chemical species from the surface to upper troposphere and lower stratosphere (UT/LS), but exactly how these processes occur and how important they are as compared to other processes are still up to debate. The main hurdle to the complete understanding of these transport processes is the difficulty in observing storm systems directly. Remote sensing data such as those obtained by radars and satellites are very valuable but they need correct interpretation before we can use them profitably. We have performed numerical simulations of thunderstorms using a physics-based cloud resolving model and compared model results with satellite observations. Many major features of observed satellite storm top images, such as cold-V, close in warm area, above anvil cirrus plumes, are successfully simulated and can be interpreted by the model physics. However, due to the limitation of resolution and other ambiguities, we have been unable to determine the real cause of some features such as the conversion of jumping cirrus to long trail plumes and whether or no small scale ( < 1 km) wave breaking occur. We are fortunate to have encountered a line of sea breeze storms along the coast of China during a flight from Beijing to Taipei in July 2106. The flight was at an altitude such that storm tops could be clearly observed. Nearly all of the mature storm cells that can be identified had very vigorous storm top activities, indicating very strong stratosphere/troposphere exchange (STE). There is no doubt that the signatures of wave breaking, i.e., jumping cirrus, occurs from very small scale (< 1 km) to tens of km. this matches our previous model results very well. Furthermore, one storm cell shows very clearly the process whereby a jumping cirrus is being transformed into a long trail cirrus plume which was often observed in satellite images. We have also obtained the corresponding Himawari-8 satellite images for this line of storms. Aircraft observation, satellite images and model results will be compared and the implications to STE discussed.

Some inconvenient truths about biosignatures involving two chemical species on Earth-like exoplanets

PubMed Central

Rein, Hanno; Fujii, Yuka; Spiegel, David S.

2014-01-01

The detection of strong thermochemical disequilibrium in the atmosphere of an extrasolar planet is thought to be a potential biosignature. In this article we present a previously unidentified kind of false positive that can mimic a disequilibrium or any other biosignature that involves two chemical species. We consider a scenario where the exoplanet hosts a moon that has its own atmosphere and neither of the atmospheres is in chemical disequilibrium. Our results show that the integrated spectrum of the planet and the moon closely resembles that of a single object in strong chemical disequilibrium. We derive a firm limit on the maximum spectral resolution that can be obtained for both directly imaged and transiting planets. The spectral resolution of even idealized space-based spectrographs that might be achievable in the next several decades is in general insufficient to break the degeneracy. Both chemical species can only be definitively confirmed in the same object if absorption features of both chemicals can be unambiguously identified and their combined depth exceeds 100%. PMID:24778224

Impact of automation on mass spectrometry.

PubMed

Zhang, Yan Victoria; Rockwood, Alan

2015-10-23

Mass spectrometry coupled to liquid chromatography (LC-MS and LC-MS/MS) is an analytical technique that has rapidly grown in popularity in clinical practice. In contrast to traditional technology, mass spectrometry is superior in many respects including resolution, specificity, multiplex capability and has the ability to measure analytes in various matrices. Despite these advantages, LC-MS/MS remains high cost, labor intensive and has limited throughput. This specialized technology requires highly trained personnel and therefore has largely been limited to large institutions, academic organizations and reference laboratories. Advances in automation will be paramount to break through this bottleneck and increase its appeal for routine use. This article reviews these challenges, shares perspectives on essential features for LC-MS/MS total automation and proposes a step-wise and incremental approach to achieve total automation through reducing human intervention, increasing throughput and eventually integrating the LC-MS/MS system into the automated clinical laboratory operations. Copyright © 2015 Elsevier B.V. All rights reserved.

What the success of brain imaging implies about the neural code

PubMed Central

Guest, Olivia; Love, Bradley C

2017-01-01

The success of fMRI places constraints on the nature of the neural code. The fact that researchers can infer similarities between neural representations, despite fMRI’s limitations, implies that certain neural coding schemes are more likely than others. For fMRI to succeed given its low temporal and spatial resolution, the neural code must be smooth at the voxel and functional level such that similar stimuli engender similar internal representations. Through proof and simulation, we determine which coding schemes are plausible given both fMRI’s successes and its limitations in measuring neural activity. Deep neural network approaches, which have been forwarded as computational accounts of the ventral stream, are consistent with the success of fMRI, though functional smoothness breaks down in the later network layers. These results have implications for the nature of the neural code and ventral stream, as well as what can be successfully investigated with fMRI. DOI: http://dx.doi.org/10.7554/eLife.21397.001 PMID:28103186

Bud break responds more strongly to daytime than night-time temperature under asymmetric experimental warming.

PubMed

Rossi, Sergio; Isabel, Nathalie

2017-01-01

Global warming is diurnally asymmetric, leading to a less cold, rather than warmer, climate. We investigated the effects of asymmetric experimental warming on plant phenology by testing the hypothesis that daytime warming is more effective in advancing bud break than night-time warming. Bud break was monitored daily in Picea mariana seedlings belonging to 20 provenances from Eastern Canada and subjected to daytime and night-time warming in growth chambers at temperatures varying between 8 and 16 °C. The higher advancements of bud break and shorter times required to complete the phenological phases occurred with daytime warming. Seedlings responded to night-time warming, but still with less advancement of bud break than under daytime warming. No advancement was observed when night-time warming was associated with a daytime cooling. The effect of the treatments was uniform across provenances. Our observations realized under controlled conditions allowed to experimentally demonstrate that bud break can advance under night-time warming, but to a lesser extent than under daytime warming. Prediction models using daily timescales could neglect the diverging influence of asymmetric warming and should be recalibrated for higher temporal resolutions. © 2016 John Wiley & Sons Ltd.

Downslope flow across the Ross Sea shelf break (Antarctica)

NASA Astrophysics Data System (ADS)

Bergamasco, A.; Budillon, G.; Carniel, S.; Defendi, V.; Meloni, R.; Paschini, E.; Sclavo, M.; Spezie, G.

2003-12-01

The analysis of some high-resolution hydrological data sets acquired during the 1997, 1998, 2001 and 2003 austral summers across the Ross Sea continental shelf break are here presented. The main focus of these cruises carried out in the framework of the Italian National Antarctic Program was the investigation of the downslope flow of the dense waters originated inside the Ross Sea. Such dense waters, flow near the bottom and, reaching the continental shelf break, ventilate the deep ocean. Two Antarctic continental shelf mechanisms can originate dense and deep waters. The former mechanism involves the formation, along the Victoria Land coasts, of a dense and saline water mass, the High Salinity Shelf Water (HSSW). The HSSW formation is linked to the rejection of salt into the water column as sea ice freezes, especially during winter, in the polynya areas, where the ice is continuously pushed offshore by the strong katabatic winds. The latter one is responsible of the formation of a supercold water mass, the Ice Shelf Water (ISW). The salt supplied by the HSSW recirculated below the Ross Ice Shelf, the latent heat of melting and the heat sink provided by the Ross Ice Shelf give rise to plumes of ISW, characterized by temperatures below the sea-surface freezing point. The dense shelf waters migrate to the continental shelf-break, spill over the shelf edge and descend the continental slope as a shelf-break gravity current, subject to friction and possibly enhanced by topographic channelling. Friction, in particular, breaks the constraint of potential vorticity conservation, counteracting the geostrophic tendency for along slope flow. The density-driven downslope motion or cascading entrains ambient water, namely the lower layer of the CDW, reaches a depth where density is the same and spreads off-slope. In fact, the cascading event is inhibited by friction without entrainment. The downslope processes are important for the ocean and climate system because they play a crucial role in the formation of oceanic deep water responsible for ocean/continental shelf exchange of organic carbon, suspended material and dissolved gases around Antarctica. In this context, this work presents the analysis of the 1997, 2001 and 2003 high-resolution surveys carried out in the western Ross Sea near Cape Adare, where the HSSW flows down the continental slope. The second study area was investigated during the 1998 survey of the Italian National Programme for Antarctic Research of the CLIMA Project, in order to follow the ISW overflow path at the shelf break in the central Ross Sea. A 3D primitive equation model was also implemented as a first step in the construction of a high-resolution process study model to explore the dynamical constraints involved in the downslope motion.

Short break and emergency respite care: what options for young people with life-limiting conditions?

PubMed

Mitchell, Tracy K; Knighting, Katherine; O'Brien, Mary R; Jack, Barbara A

2016-02-01

Service providers face difficult decisions about how best to develop services for the increasing numbers of young people with life-limiting conditions who require palliative care. To explore alternative short break and emergency respite care options to children's hospice care. A two-phase evaluation with young people, families and professionals. Phase 1: qualitative semi-structured interviews and focus groups (n=53). Phase 2: mixed-method survey (n=82), qualitative findings only. There were few, or no, appropriate short break and emergency respite care alternatives when children's hospice care was not available that can meet the need of young people with life-limiting conditions, creating anxiety for children's hospice users and those leaving the service as a result of reaching transition age or through no longer meeting the children's hospice eligibility criteria. Access to appropriate short break and emergency respite care is required to prevent lifelong negative consequences for young people with life-limiting conditions, their family and society. Research is undoubtedly required to explore the impact and outcomes of children's hospice discharge for young people and their family. Particular attention should be paid to the lack of services for an increasing population making the transition from children's hospices.

Discreteness of time in the evolution of the universe

NASA Astrophysics Data System (ADS)

Faizal, Mir; Ali, Ahmed Farag; Das, Saurya

2017-04-01

In this paper, we will first derive the Wheeler-DeWitt equation for the generalized geometry which occurs in M-theory. Then we will observe that M2-branes act as probes for this generalized geometry, and as M2-branes have an extended structure, their extended structure will limits the resolution to which this generalized geometry can be defined. We will demonstrate that this will deform the Wheeler-DeWitt equation for the generalized geometry. We analyze such a deformed Wheeler-DeWitt equation in the minisuperspace approximation, and observe that this deformation can be used as a solution to the problem of time. This is because this deformation gives rise to time crystals in our universe due to the spontaneous breaking of time reparametrization invariance.

Multiresolution analysis of characteristic length scales with high-resolution topographic data

NASA Astrophysics Data System (ADS)

Sangireddy, Harish; Stark, Colin P.; Passalacqua, Paola

2017-07-01

Characteristic length scales (CLS) define landscape structure and delimit geomorphic processes. Here we use multiresolution analysis (MRA) to estimate such scales from high-resolution topographic data. MRA employs progressive terrain defocusing, via convolution of the terrain data with Gaussian kernels of increasing standard deviation, and calculation at each smoothing resolution of (i) the probability distributions of curvature and topographic index (defined as the ratio of slope to area in log scale) and (ii) characteristic spatial patterns of divergent and convergent topography identified by analyzing the curvature of the terrain. The MRA is first explored using synthetic 1-D and 2-D signals whose CLS are known. It is then validated against a set of MARSSIM (a landscape evolution model) steady state landscapes whose CLS were tuned by varying hillslope diffusivity and simulated noise amplitude. The known CLS match the scales at which the distributions of topographic index and curvature show scaling breaks, indicating that the MRA can identify CLS in landscapes based on the scaling behavior of topographic attributes. Finally, the MRA is deployed to measure the CLS of five natural landscapes using meter resolution digital terrain model data. CLS are inferred from the scaling breaks of the topographic index and curvature distributions and equated with (i) small-scale roughness features and (ii) the hillslope length scale.

Remote Sensing Characteristics of Wave Breaking Rollers

NASA Astrophysics Data System (ADS)

Haller, M. C.; Catalan, P.

2006-12-01

The wave roller has a primary influence on the balances of mass and momentum in the surf zone (e.g. Svendsen, 1984; Dally and Brown, 1995; Ruessink et al., 2001). In addition, the roller area and its angle of inclination on the wave front are important quantities governing the dissipation rates in breaking waves (e.g Madsen et al., 1997). Yet, there have been very few measurements published of individual breaking wave roller geometries in shallow water. A number of investigators have focused on observations of the initial jet-like motion at the onset of breaking before the establishment of the wave roller (e.g. Basco, 1985; Jansen, 1986), while Govender et al. (2002) provide observations of wave roller vertical cross-sections and angles of inclination for a pair of laboratory wave conditions. Nonetheless, presently very little is known about the growth, evolution, and decay of this aerated region of white water as it propagates through the surf zone; mostly due to the inherent difficulties in making the relevant observations. The present work is focused on analyzing observations of the time and space scales of individual shallow water breaking wave rollers as derived from remote sensing systems. Using a high-resolution video system in a large-scale laboratory facility, we have obtained detailed measurements of the growth and evolution of the wave breaking roller. In addition, by synchronizing the remote video with in-situ wave gages, we are able to directly relate the video intensity signal to the underlying wave shape. Results indicate that the horizontal length scale of breaking wave rollers differs significantly from the previous observations of Duncan (1981), which has been a traditional basis for roller model parameterizations. The overall approach to the video analysis is new in the sense that we concentrate on individual breaking waves, as opposed to the more commonly used time-exposure technique. In addition, a new parameter of interest, denoted Imax, is introduced based on the envelope of the intensity signal. The parameter is shown to be much less sensitive to trailing wave breaking foam, which typically corrupts time-exposure data. In the present work this parameter is shown to provide high-resolution information regarding the onset of wave breaking and the spatial evolution of the wave roller. Ongoing work will attempt to relate the shoreward transformation of the intensity maximum and the geometric characteristics of the wave roller to the spatial distribution of wave breaking dissipation. Finally, we will compare wave breaking characteristics as imaged by two separate remote sensors. Synoptic images from both video and microwave radar remote sensors were obtained in September of 2005 at Duck, NC. This combination of the two observing systems will allow direct quantitative comparisons between the two imaging mechanisms and lead to a better understanding of the strengths and weaknesses of both for nearshore research and observational remote sensing.

Keeping It Real: Exploring an Interdisciplinary Breaking Bad News Role-Play as an Integrative Learning Opportunity

ERIC Educational Resources Information Center

Sweeney, Catherine; O'Sullivan, Eleanor; McCarthy, Marian

2015-01-01

Palliative care is a complex area of healthcare best delivered by an interdisciplinary team approach. Breaking bad news is an inherent part of caring for people with life-limiting conditions. This study aims to explore an interdisciplinary breaking bad news role-play in a palliative care module. Participants were undergraduate medical and nursing…

Variations of heat transport in the northwestern Pacific marginal seas inferred from high-resolution reanalysis

NASA Astrophysics Data System (ADS)

Seo, Gwang-Ho; Cho, Yang-Ki; Choi, Byoung-Ju

2014-02-01

High-resolution reanalysis of heat transport in the northwestern Pacific marginal seas was conducted for the period January 1980-December 2009 using ensemble Kalman filter. An ocean circulation model with a grid of 0.1 × 0.1° horizontal resolution and 20 vertical levels was used. Atmospheric forcing data from daily European Centre for Medium-Range Weather Forecasts were used in the ocean model. The assimilated data for the reanalysis were based on available observations of hydrographic profiles, including field surveys and Argo float and satellite-observed sea-surface temperature data. This study focused on mean and temporal variations in oceanic heat transport within the major straits among the marginal seas over 30 years. The mean heat transport in the Korea/Tsushima Strait and onshore transport across the shelf break in the East China Sea (ECS), Taiwan Strait, Tsugaru Strait, and Soya Strait were 182, 123, 82, 100, and 34 × 1012 W, respectively. The long-term trends in heat transport through the Korea/Tsushima Strait and Tsugaru Strait and onshore transport across the shelf break of the ECS were increasing, whereas the trend in heat transport through the Taiwan Strait was decreasing. There was little long-term change in heat transport in the Soya Strait. These long-term changes in heat transport through the Korea/Tsushima Strait, across the shelf of the ECS, and through the Taiwan Strait may be related to increased northeasterly wind stress in the ECS, which drives Ekman transport onto the shelf across the shelf break.

Esophageal mucosal breaks in gastroesophageal reflux disease partially responsive to proton pump inhibitor therapy.

PubMed

Shaheen, Nicholas J; Denison, Hans; Björck, Karin; Silberg, Debra G

2013-04-01

Approximately 20-30% of patients with gastroesophageal reflux disease (GERD) do not experience complete symptom resolution during proton pump inhibitor (PPI) therapy. The aim of this study was to determine the prevalence of esophageal mucosal breaks among patients who have a partial response to PPI therapy. This was an analysis of data from a phase 2b clinical trial carried out to assess the efficacy and safety of a reflux inhibitor, lesogaberan (AZD3355), as an add-on to PPI therapy in this patient population (clinicaltrials.gov reference: NCT01005251). A total of 661 patients with persistent GERD symptoms who had received a minimum of 4 weeks of PPI therapy were included in the study. The prevalence of esophageal mucosal breaks was assessed according to (i) the most recent endoscopy results from within the previous 24 months, if available ("historical" endoscopies), and (ii) the results of endoscopies performed at study baseline ("baseline" endoscopies). Baseline endoscopies were not carried out in patients who had a historical endoscopy showing an absence of esophageal mucosal breaks. Historical endoscopy results were available for 244 patients, of whom 48 (19.7%) had esophageal mucosal breaks. Baseline endoscopies were carried out in 465 patients, of whom 146 (31.4%) had esophageal mucosal breaks. Sensitivity analyses showed a prevalence of esophageal mucosal breaks of 20-30%. In both the historical and baseline endoscopies, most esophageal mucosal breaks were Los Angeles grades A or B. In patients with GERD symptoms partially responsive to PPI therapy, mild-to-moderate severity esophageal mucosal breaks are common (prevalence 20-30%), and may contribute to symptom etiology.

Comparison of occlusion break responses and vacuum rise times of phacoemulsification systems.

PubMed

Sharif-Kashani, Pooria; Fanney, Douglas; Injev, Val

2014-07-30

Occlusion break surge during phacoemulsification cataract surgery can lead to potential surgical complications. The purpose of this study was to quantify occlusion break surge and vacuum rise time of current phacoemulsification systems used in cataract surgery. Occlusion break surge at vacuum pressures between 200 and 600 mmHg was assessed with the Infiniti® Vision System, the WhiteStar Signature® Phacoemulsification System, and the Centurion® Vision System using gravity-fed fluidics. Centurion Active FluidicsTM were also tested at multiple intraoperative pressure target settings. Vacuum rise time was evaluated for Infiniti, WhiteStar Signature, Centurion, and Stellaris® Vision Enhancement systems. Rise time to vacuum limits of 400 and 600 mmHg was assessed at flow rates of 30 and 60 cc/minute. Occlusion break surge was analyzed by 2-way analysis of variance. The Centurion system exhibited substantially less occlusion break surge than the other systems tested. Surge area with Centurion Active Fluidics was similar to gravity fluidics at an equivalent bottle height. At all Centurion Active Fluidics intraoperative pressure target settings tested, surge was smaller than with Infiniti and WhiteStar Signature. Infiniti had the fastest vacuum rise time and Stellaris had the slowest. No system tested reached the 600-mmHg vacuum limit. In this laboratory study, Centurion had the least occlusion break surge and similar vacuum rise times compared with the other systems tested. Reducing occlusion break surge may increase safety of phacoemulsification cataract surgery.

Comparison of occlusion break responses and vacuum rise times of phacoemulsification systems

PubMed Central

2014-01-01

Background Occlusion break surge during phacoemulsification cataract surgery can lead to potential surgical complications. The purpose of this study was to quantify occlusion break surge and vacuum rise time of current phacoemulsification systems used in cataract surgery. Methods Occlusion break surge at vacuum pressures between 200 and 600 mmHg was assessed with the Infiniti® Vision System, the WhiteStar Signature® Phacoemulsification System, and the Centurion® Vision System using gravity-fed fluidics. Centurion Active FluidicsTM were also tested at multiple intraoperative pressure target settings. Vacuum rise time was evaluated for Infiniti, WhiteStar Signature, Centurion, and Stellaris® Vision Enhancement systems. Rise time to vacuum limits of 400 and 600 mmHg was assessed at flow rates of 30 and 60 cc/minute. Occlusion break surge was analyzed by 2-way analysis of variance. Results The Centurion system exhibited substantially less occlusion break surge than the other systems tested. Surge area with Centurion Active Fluidics was similar to gravity fluidics at an equivalent bottle height. At all Centurion Active Fluidics intraoperative pressure target settings tested, surge was smaller than with Infiniti and WhiteStar Signature. Infiniti had the fastest vacuum rise time and Stellaris had the slowest. No system tested reached the 600-mmHg vacuum limit. Conclusions In this laboratory study, Centurion had the least occlusion break surge and similar vacuum rise times compared with the other systems tested. Reducing occlusion break surge may increase safety of phacoemulsification cataract surgery. PMID:25074069

Childhood Forearm Breaks Resulting from Mild Trauma May Indicate Bone Deficits

MedlinePlus

... a powerful new technology called high-resolution peripheral quantitative computed tomography (HRpQCT), which, unlike DXA, can assess ... persist throughout life. The investigators concluded that additional research is needed to determine if childhood bone weakness ...

Nonperturbative study of dynamical SUSY breaking in N =(2 ,2 ) Yang-Mills theory

NASA Astrophysics Data System (ADS)

Catterall, Simon; Jha, Raghav G.; Joseph, Anosh

2018-03-01

We examine the possibility of dynamical supersymmetry breaking in two-dimensional N =(2 ,2 ) supersymmetric Yang-Mills theory. The theory is discretized on a Euclidean spacetime lattice using a supersymmetric lattice action. We compute the vacuum energy of the theory at finite temperature and take the zero-temperature limit. Supersymmetry will be spontaneously broken in this theory if the measured ground-state energy is nonzero. By performing simulations on a range of lattices up to 96 ×96 we are able to perform a careful extrapolation to the continuum limit for a wide range of temperatures. Subsequent extrapolations to the zero-temperature limit yield an upper bound on the ground-state energy density. We find the energy density to be statistically consistent with zero in agreement with the absence of dynamical supersymmetry breaking in this theory.

Thorough small-angle X-ray scattering analysis of the instability of liquid micro-jets in air.

PubMed

Marmiroli, Benedetta; Cacho-Nerin, Fernando; Sartori, Barbara; Pérez, Javier; Amenitsch, Heinz

2014-01-01

Liquid jets are of interest, both for their industrial relevance and for scientific applications (more important, in particular for X-rays, after the advent of free-electron lasers that require liquid jets as sample carrier). Instability mechanisms have been described theoretically and by numerical simulation, but confirmed by few experimental techniques. In fact, these are mainly based on cameras, which is limited by the imaging resolution, and on light scattering, which is hindered by absorption, reflection, Mie scattering and multiple scattering due to complex air/liquid interfaces during jet break-up. In this communication it is demonstrated that synchrotron small-angle X-ray scattering (SAXS) can give quantitative information on liquid jet dynamics at the nanoscale, by detecting time-dependent morphology and break-up length. Jets ejected from circular tubes of different diameters (100-450 µm) and speeds (0.7-21 m s(-1)) have been explored to cover the Rayleigh and first wind-induced regimes. Various solvents (water, ethanol, 2-propanol) and their mixtures have been examined. The determination of the liquid jet behaviour becomes essential, as it provides background data in subsequent studies of chemical and biological reactions using SAXS or X-ray diffraction based on synchrotron radiation and free-electron lasers.

High Count-Rate Study of Two TES X-Ray Microcalorimeters With Different Transition Temperatures

NASA Technical Reports Server (NTRS)

Lee, Sang-Jun; Adams, Joseph S.; Bandler, Simon R.; Betancourt-Martinez, Gabriele L.; Chervenak, James A.; Eckart, Megan E.; Finkbeiner, Fred M.; Kelley, Richard L.; Kilbourne, Caroline A.; Porter, Frederick S.;

Variability and Dynamics of the Yucatan Upwelling: High-Resolution Simulations

NASA Astrophysics Data System (ADS)

Jouanno, J.; Pallàs-Sanz, E.; Sheinbaum, J.

2018-02-01

The Yucatan shelf in the southern Gulf of Mexico is under the influence of an upwelling that uplifts cool and nutrient rich waters over the continental shelf. The analysis of a set of high-resolution (Δx = Δy ≈ 2.8 km) simulations of the Gulf of Mexico shows two dominant modes of variability of the Yucatan upwelling system: (1) a low-frequency mode related to variations in position and intensity of the Loop Current along the shelf, with upwelling intensified when the Loop Current is strong and approaches to the Yucatan shelf break and (2) a high-frequency mode with peak frequency in the 6-10 days band related to wind-forced coastal waves that force vertical velocities along the eastern Yucatan shelf break. To first order, the strength and position of the Loop Current are found to control the intensity of the upwelling, but we show that high-frequency winds also contribute (˜17%) to a net input of cool waters (<22.5°C) on the Yucatan shelf. Finally, although more observational studies are needed to corroborate the topographic character of the Yucatan upwelling system, this study reveals the key role played by a notch along the Yucatan shelf break: a sensitivity simulation without the notch shows a 55% reduction of the upwelling.

Evolutionarily diverse determinants of meiotic DNA break and recombination landscapes across the genome

PubMed Central

Fowler, Kyle R.; Sasaki, Mariko; Milman, Neta

2014-01-01

Fission yeast Rec12 (Spo11 homolog) initiates meiotic recombination by forming developmentally programmed DNA double-strand breaks (DSBs). DSB distributions influence patterns of heredity and genome evolution, but the basis of the highly nonrandom choice of Rec12 cleavage sites is poorly understood, largely because available maps are of relatively low resolution and sensitivity. Here, we determined DSBs genome-wide at near-nucleotide resolution by sequencing the oligonucleotides attached to Rec12 following DNA cleavage. The single oligonucleotide size class allowed us to deeply sample all break events. We find strong evidence across the genome for differential DSB repair accounting for crossover invariance (constant cM/kb in spite of DSB hotspots). Surprisingly, about half of all crossovers occur in regions where DSBs occur at low frequency and are widely dispersed in location from cell to cell. These previously undetected, low-level DSBs thus play an outsized and crucial role in meiosis. We further find that the influence of underlying nucleotide sequence and chromosomal architecture differs in multiple ways from that in budding yeast. DSBs are not strongly restricted to nucleosome-depleted regions, as they are in budding yeast, but are nevertheless spatially influenced by chromatin structure. Our analyses demonstrate that evolutionarily fluid factors contribute to crossover initiation and regulation. PMID:25024163

Dynamic dependence on ATR and ATM for double-strand break repair in human embryonic stem cells and neural descendants.

PubMed

Adams, Bret R; Golding, Sarah E; Rao, Raj R; Valerie, Kristoffer

2010-04-02

The DNA double-strand break (DSB) is the most toxic form of DNA damage. Studies aimed at characterizing DNA repair during development suggest that homologous recombination repair (HRR) is more critical in pluripotent cells compared to differentiated somatic cells in which nonhomologous end joining (NHEJ) is dominant. We have characterized the DNA damage response (DDR) and quality of DNA double-strand break (DSB) repair in human embryonic stem cells (hESCs), and in vitro-derived neural cells. Resolution of ionizing radiation-induced foci (IRIF) was used as a surrogate for DSB repair. The resolution of gamma-H2AX foci occurred at a slower rate in hESCs compared to neural progenitors (NPs) and astrocytes perhaps reflective of more complex DSB repair in hESCs. In addition, the resolution of RAD51 foci, indicative of active homologous recombination repair (HRR), showed that hESCs as well as NPs have high capacity for HRR, whereas astrocytes do not. Importantly, the ATM kinase was shown to be critical for foci formation in astrocytes, but not in hESCs, suggesting that the DDR is different in these cells. Blocking the ATM kinase in astrocytes not only prevented the formation but also completely disassembled preformed repair foci. The ability of hESCs to form IRIF was abrogated with caffeine and siRNAs targeted against ATR, implicating that hESCs rely on ATR, rather than ATM for regulating DSB repair. This relationship dynamically changed as cells differentiated. Interestingly, while the inhibition of the DNA-PKcs kinase (and presumably non-homologous endjoining [NHEJ]) in astrocytes slowed IRIF resolution it did not in hESCs, suggesting that repair in hESCs does not utilize DNA-PKcs. Altogether, our results show that hESCs have efficient DSB repair that is largely ATR-dependent HRR, whereas astrocytes critically depend on ATM for NHEJ, which, in part, is DNA-PKcs-independent.

The Working of Circuit Breakers Within Percolation Models for Financial Markets

NASA Astrophysics Data System (ADS)

Ehrenstein, Gudrun; Westerhoff, Frank

We use a modified Cont-Bouchaud model to explore the effectiveness of trading breaks. The modifications include that the trading activity of the market participants depends positively on historical volatility and that the orders of the agents are conditioned on the observed mispricing. Trading breaks, also called circuit breakers, interrupt the trading process when prices are about to exceed a pre-specified limit. We find that trading breaks are a useful instrument to stabilize financial markets. In particular, trading breaks may reduce price volatility and deviations from fundamentals.

Autosomal mutations in mouse kidney epithelial cells exposed to high-energy protons in vivo or in culture.

PubMed

Turker, Mitchell S; Grygoryev, Dmytro; Dan, Cristian; Eckelmann, Bradley; Lasarev, Michael; Gauny, Stacey; Kwoh, Ely; Kronenberg, Amy

2013-05-01

Proton exposure induces mutations and cancer, which are presumably linked. Because protons are abundant in the space environment and significant uncertainties exist for the effects of space travel on human health, the purpose of this study was to identify the types of mutations induced by exposure of mammalian cells to 4-5 Gy of 1 GeV protons. We used an assay that selects for mutations affecting the chromosome 8-encoded Aprt locus in mouse kidney cells and selected mutants after proton exposure both in vivo and in cell culture. A loss of heterozygosity (LOH) assay for DNA preparations from the in vivo-derived kidney mutants revealed that protons readily induced large mutational events. Fluorescent in situ hybridization painting for chromosome 8 showed that >70% of proton-induced LOH patterns resembling mitotic recombination were in fact the result of nonreciprocal chromosome translocations, thereby demonstrating an important role for DNA double-strand breaks in proton mutagenesis. Large interstitial deletions, which also require the formation and resolution of double-strand breaks, were significantly induced in the cell culture environment (14% of all mutants), but to a lesser extend in vivo (2% of all mutants) suggesting that the resolution of proton-induced double-strand breaks can differ between the intact tissue and cell culture microenvironments. In total, the results demonstrate that double-strand break formation is a primary determinant for proton mutagenesis in epithelial cell types and suggest that resultant LOH for significant genomic regions play a critical role in proton-induced cancers.

Cracks dynamics under tensional stress - a DEM approach

NASA Astrophysics Data System (ADS)

Debski, Wojciech; Klejment, Piotr; Kosmala, Alicja; Foltyn, Natalia; Szpindler, Maciej

2017-04-01

Breaking and fragmentation of solid materials is an extremely complex process involving scales ranging from an atomic scale (breaking inter-atomic bounds) up to thousands of kilometers in case of catastrophic earthquakes (in energy scale it ranges from single eV up to 1024 J). Such a large scale span of breaking processes opens lot of questions like, for example, scaling of breaking processes, existence of factors controlling final size of broken area, existence of precursors, dynamics of fragmentation, to name a few. The classical approach to study breaking process at seismological scales, i.e., physical processes in earthquake foci, is essentially based on two factors: seismic data (mostly) and the continuum mechanics (including the linear fracture mechanics). Such approach has been gratefully successful in developing kinematic (first) and dynamic (recently) models of seismic rupture and explaining many of earthquake features observed all around the globe. However, such approach will sooner or latter face a limitation due to a limited information content of seismic data and inherit limitations of the fracture mechanics principles. A way of avoiding this expected limitation is turning an attention towards a well established in physics method of computational simulations - a powerful branch of contemporary physics. In this presentation we discuss preliminary results of analysis of fracturing dynamics under external tensional forces using the Discrete Element Method approach. We demonstrate that even under a very simplified tensional conditions, the fragmentation dynamics is a very complex process, including multi-fracturing, spontaneous fracture generation and healing, etc. We also emphasis a role of material heterogeneity on the fragmentation process.

Using CETUS to study the first stars and first metals

NASA Astrophysics Data System (ADS)

Roederer, Ian; CETUS Team

2018-01-01

The nucleosynthetic signatures of the first stars and supernovae are imprinted in the compositions of the most metal-poor stars found today. Only a few tens of absorption lines are commonly found in the optical spectra of the second-generation stars, so only 5-10 elements are regularly detected. Many others (Be, B, Si, P, S, Sc, V, Cr, Mn, Co, Ni, Cu, and Zn) are expected to be present but are rarely detected, and the upper limits derived from their optical non-detections are often uninteresting. The UV part of the spectrum accessible to the high-resolution UV spectrograph on CETUS would enable all of these elements to be detected if present in the most metal-poor stars known. We illustrate some of the ground-breaking observations of these stars that could be made with this mission.

Least Squares Shadowing Sensitivity Analysis of Chaotic Flow Around a Two-Dimensional Airfoil

NASA Technical Reports Server (NTRS)

Blonigan, Patrick J.; Wang, Qiqi; Nielsen, Eric J.; Diskin, Boris

2016-01-01

Gradient-based sensitivity analysis has proven to be an enabling technology for many applications, including design of aerospace vehicles. However, conventional sensitivity analysis methods break down when applied to long-time averages of chaotic systems. This breakdown is a serious limitation because many aerospace applications involve physical phenomena that exhibit chaotic dynamics, most notably high-resolution large-eddy and direct numerical simulations of turbulent aerodynamic flows. A recently proposed methodology, Least Squares Shadowing (LSS), avoids this breakdown and advances the state of the art in sensitivity analysis for chaotic flows. The first application of LSS to a chaotic flow simulated with a large-scale computational fluid dynamics solver is presented. The LSS sensitivity computed for this chaotic flow is verified and shown to be accurate, but the computational cost of the current LSS implementation is high.

Snow depth spatial structure from hillslope to basin scale

NASA Astrophysics Data System (ADS)

Deems, J. S.

2017-12-01

Knowledge of spatial patterns of snow accumulation is required for understanding the hydrology, climatology, and ecology of mountain regions. Spatial structure in snow accumulation patterns changes with the scale of observation, a feature that has been characterized using fractal dimensions calculated from lidar-derived snow depth maps: fractal scaling structure at short length scales, with a `scale break' transition to more stochastic patterns at longer separation distances. Previous work has shown that this fractal structure of snow depth distributions differs between sites with different vegetation and terrain characteristics. Forested areas showed a transition to a nearly random spatial distribution at a much shorter lag distance than do unforested sites, enabling a statistical characterization. Alpine areas, however, showed strong spatial structure for a much wider scale range, and were the source of the dominant spatial pattern observable over a wider area. These spatial structure characteristics suggest that the choice of measurement or model resolution (satellite sensor, DEM, field survey point spacing, etc.) will strongly affect the estimates of snow volume or mass, as well as the magnitude of spatial variability. These prior efforts used data sets that were high resolution ( 1 m laser point spacing) but of limited extent ( 1 km2), constraining detection of scale features such as fractal dimension or scale breaks to areas of relatively similar characteristics and to lag distances of under 500 m. New datasets available from the NASA JPL Airborne Snow Observatory (ASO) provide similar resolution but over large areas, enabling assessment of snow spatial structure across an entire watershed, or in similar vegetation or physiography but in different parts of the basin. Additionally, the multi-year ASO time series allows an investigation into the temporal stability of these scale characteristics, within a single snow season and between seasons of strongly varying accumulation totals and patterns. This presentation will explore initial results from this study, using data from the Tuolumne River Basin in California, USA. Fractal scaling characteristics derived from ASO lidar snow depth measurements are examined at the basin scale, as well as in varying topographic and forest cover environments.

Optoelectronic Picosecond Detection of Synchrotron X-rays

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

Durbin, Stephen M.

2017-08-04

The goal of this research program was to develop a detector that would measure x-ray time profiles with picosecond resolution. This was specifically aimed for use at x-ray synchrotrons, where x-ray pulse profiles have Gaussian time spreads of 50-100 ps (FWHM), so the successful development of such a detector with picosecond resolution would permit x-ray synchrotron studies to break through the pulse width barrier. That is, synchrotron time-resolved studies are currently limited to pump-probe studies that cannot reveal dynamics faster than ~50 ps, whereas the proposed detector would push this into the physically important 1 ps domain. The results ofmore » this research effort, described in detail below, are twofold: 1) the original plan to rely on converting electronic signals from a semiconductor sensor into an optical signal proved to be insufficient for generating signals with the necessary time resolution and sensitivity to be widely applicable; and 2) an all-optical method was discovered whereby the x-rays are directly absorbed in an optoelectronic material, lithium tantalate, which can then be probed by laser pulses with the desired picosecond sensitivity for detection of synchrotron x-rays. This research program has also produced new fundamental understanding of the interaction of x-rays and optical lasers in materials that has now created a viable path for true picosecond detection of synchrotron x-rays.« less

IMPROVEMENT OF WATER MAIN INSPECTION TECHNOLOGY

EPA Science Inventory

This document is a handout of a slide presentation that addresses improvement of water main inspection technology. The slide presentation addresses the need for improved inspection technology (e.g., 237,000 main breaks/yr); the limits on main break prevention; and, the adverse ...

Monitoring structural breaks in vegetation dynamics of the nature reserve Königsbrücker Heide

NASA Astrophysics Data System (ADS)

Wessollek, Christine; Karrasch, Pierre

2017-10-01

Nowadays remote sensing is a well-established method and technique of providing data. The current development shows the availability of systems with very high geometric resolution for the monitoring of vegetation. At the same time, however, the value of temporally high-resolution data is underestimated, particularly in applications focusing on the detection of short-term changes. These can be natural processes like natural disasters as well as changes caused by anthropogenic interventions. These include economic activities such as forestry, agriculture or mining but also processes which are intended to convert previously used areas into natural or near-natural surfaces. The K¨onigsbr¨ucker Heide is a former military training site located about 30 km north of the Saxon state capitol Dresden. After the withdrawal of the Soviet forces in 1992 and after nearly 100 years of military use this site was declared as nature reserve in 1996. The management of the whole protection area is implemented in three different management zone. Based on MODIS-NDVI time series between 2000 and 2016 different developments are apparent in the nature development zone and the zone of controlled succession. Nevertheless, the analyses also show that short-term changes, so called breaks in the vegetation development cannot be described using linear trend models. The complete understanding of vegetation trends is only given if discontinuities in vegetation development are considered. Structural breaks in the NDVI time series can be found simultaneously in the whole study area. Hence it can be assumed that these breaks have a more natural character, caused for example by climatic conditions like temperature or precipitation. Otherwise, especially in the zone of controlled succession structural breaks can be detected which cannot be traced back to natural conditions. Final analyses of the spatial distribution of breakpoints as well as their frequency depending on the respective protection zone allow a detailed view to vegetation development in the K¨onigsbr¨ucker Heide.

Characterizing DNA Repair Processes at Transient and Long-lasting Double-strand DNA Breaks by Immunofluorescence Microscopy.

PubMed

Murthy, Vaibhav; Dacus, Dalton; Gamez, Monica; Hu, Changkun; Wendel, Sebastian O; Snow, Jazmine; Kahn, Andrew; Walterhouse, Stephen H; Wallace, Nicholas A

2018-06-08

The repair of double-stranded breaks (DSBs) in DNA is a highly coordinated process, necessitating the formation and resolution of multi-protein repair complexes. This process is regulated by a myriad of proteins that promote the association and disassociation of proteins to these lesions. Thanks in large part to the ability to perform functional screens of a vast library of proteins, there is a greater appreciation of the genes necessary for the double-strand DNA break repair. Often knockout or chemical inhibitor screens identify proteins involved in repair processes by using increased toxicity as a marker for a protein that is required for DSB repair. Although useful for identifying novel cellular proteins involved in maintaining genome fidelity, functional analysis requires the determination of whether the protein of interest promotes localization, formation, or resolution of repair complexes. The accumulation of repair proteins can be readily detected as distinct nuclear foci by immunofluorescence microscopy. Thus, association and disassociation of these proteins at sites of DNA damage can be accessed by observing these nuclear foci at representative intervals after the induction of double-strand DNA breaks. This approach can also identify mis-localized repair factor proteins, if repair defects do not simultaneously occur with incomplete delays in repair. In this scenario, long-lasting double-strand DNA breaks can be engineered by expressing a rare cutting endonuclease (e.g., I-SceI) in cells where the recognition site for the said enzyme has been integrated into the cellular genome. The resulting lesion is particularly hard to resolve as faithful repair will reintroduce the enzyme's recognition site, prompting another round of cleavage. As a result, differences in the kinetics of repair are eliminated. If repair complexes are not formed, localization has been impeded. This protocol describes the methodology necessary to identify changes in repair kinetics as well as repair protein localization.

The application of dam break monitoring based on BJ-2 images

NASA Astrophysics Data System (ADS)

Cui, Yan; Li, Suju; Wu, Wei; Liu, Ming

2018-03-01

Flood is one of the major disasters in China. There are heavy intensity and wide range rainstorm during flood season in eastern part of China, and the flood control capacity of rivers is lower somewhere, so the flood disaster is abrupt and caused lots of direct economic losses. In this paper, based on BJ-2 Spatio-temporal resolution remote sensing data, reference image, 30-meter Global Land Cover Dataset(GlobeLand 30) and basic geographic data, forming Dam break monitoring model which including BJ-2 date processing sub-model, flood inundation range monitoring sub-model, dam break change monitoring sub-model and crop inundation monitoring sub-model. Case analysis in Poyang County Jiangxi province in 20th, Jun, 2016 show that the model has a high precision and could monitoring flood inundation range, crops inundation range and breach.

Current conduction mechanism and electrical break-down in InN grown on GaN

NASA Astrophysics Data System (ADS)

Kuzmik, J.; Fleury, C.; Adikimenakis, A.; Gregušová, D.; Ťapajna, M.; Dobročka, E.; Haščík, Š.; Kučera, M.; Kúdela, R.; Androulidaki, M.; Pogany, D.; Georgakilas, A.

2017-06-01

Current conduction mechanism, including electron mobility, electron drift velocity (vd) and electrical break-down have been investigated in a 0.5 μm-thick (0001) InN layer grown by molecular-beam epitaxy on a GaN/sapphire template. Electron mobility (μ) of 1040 cm2/Vs and a free electron concentration (n) of 2.1 × 1018 cm-3 were measured at room temperature with only a limited change down to 20 K, suggesting scattering on dislocations and ionized impurities. Photoluminescence spectra and high-resolution X-ray diffraction correlated with the Hall experiment showing an emission peak at 0.69 eV, a full-width half-maximum of 30 meV, and a dislocation density Ndis ˜ 5.6 × 1010 cm-2. Current-voltage (I-V) characterization was done in a pulsed (10 ns-width) mode on InN resistors prepared by plasma processing and Ohmic contacts evaporation. Resistors with a different channel length ranging from 4 to 15.8 μm obeyed the Ohm law up to an electric field intensity Eknee ˜ 22 kV/cm, when vd ≥ 2.5 × 105 m/s. For higher E, I-V curves were nonlinear and evolved with time. Light emission with a photon energy > 0.7 eV has been observed already at modest Erad of ˜ 8.3 kV/cm and consequently, a trap-assisted interband tunneling was suggested to play a role. At Eknee ˜ 22 kV/cm, we assumed electron emission from traps, with a positive feed-back for the current enhancement. Catastrophic break-down appeared at E ˜ 25 kV/cm. Reduction of Ndis was suggested to fully exploit InN unique prospects for future high-frequency devices.

Staggered chiral random matrix theory

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

Osborn, James C.

2011-02-01

We present a random matrix theory for the staggered lattice QCD Dirac operator. The staggered random matrix theory is equivalent to the zero-momentum limit of the staggered chiral Lagrangian and includes all taste breaking terms at their leading order. This is an extension of previous work which only included some of the taste breaking terms. We will also present some results for the taste breaking contributions to the partition function and the Dirac eigenvalues.

Numerical simulation of evaluation of surface breaking cracks by array-lasers generated narrow-band SAW

NASA Astrophysics Data System (ADS)

Dong, Li-Ming; Ni, Chen-Yin; Shen, Zhong-Hua; Ni, Xiao-Wu

2011-09-01

Most of the factors limiting the extensive application of laser-based ultrasonic for nondestructive evaluation of surface breaking crack are its poor sensitivity, low efficiency relative to conventional contact ultrasonic methods and limit on the dimension of the cracks. For this reason, a new technique that multiplepulse narrow-band ultrasound generated by laser arrays has been proposed. It is found that crack detection dependent on spectrum of narrow-band ultrasound generated by laser arrays can be operated with low amplitude requirements. In this paper, the narrow-band ultrasound generated by pulse laser arrays interacting with surface breaking cracks has been simulated in detail by the finite element method (FEM) according to the thermoelastic theory. The pulsed array lasers were assumed to be transient heat source, and the surface acoustic wave (SAW) which propagating on the top of the plate was computed based on thermoelastic theory. Then the frequency spectrums of both reflected waves by crack and transmission ones through crack were compared with the direct waves. Results demonstrate that multiple-frequency components of the narrow-band ultrasound were varied with change of the depth of surface breaking cracks significantly, which provides the possibility for precise evaluation of surface breaking cracks.

Hydrodynamic modeling of tsunamis from the Currituck landslide

USGS Publications Warehouse

Geist, E.L.; Lynett, P.J.; Chaytor, J.D.

2009-01-01

Tsunami generation from the Currituck landslide offshore North Carolina and propagation of waves toward the U.S. coastline are modeled based on recent geotechnical analysis of slide movement. A long and intermediate wave modeling package (COULWAVE) based on the non-linear Boussinesq equations are used to simulate the tsunami. This model includes procedures to incorporate bottom friction, wave breaking, and overland flow during runup. Potential tsunamis generated from the Currituck landslide are analyzed using four approaches: (1) tsunami wave history is calculated from several different scenarios indicated by geotechnical stability and mobility analyses; (2) a sensitivity analysis is conducted to determine the effects of both landslide failure duration during generation and bottom friction along the continental shelf during propagation; (3) wave history is calculated over a regional area to determine the propagation of energy oblique to the slide axis; and (4) a high-resolution 1D model is developed to accurately model wave breaking and the combined influence of nonlinearity and dispersion during nearshore propagation and runup. The primary source parameter that affects tsunami severity for this case study is landslide volume, with failure duration having a secondary influence. Bottom friction during propagation across the continental shelf has a strong influence on the attenuation of the tsunami during propagation. The high-resolution 1D model also indicates that the tsunami undergoes nonlinear fission prior to wave breaking, generating independent, short-period waves. Wave breaking occurs approximately 40-50??km offshore where a tsunami bore is formed that persists during runup. These analyses illustrate the complex nature of landslide tsunamis, necessitating the use of detailed landslide stability/mobility models and higher-order hydrodynamic models to determine their hazard.

Advanced Methods of Nondestructive Inspection of Composite Structures Based on Limited Angle X-Ray Computed Tomography

NASA Astrophysics Data System (ADS)

Bostaph, Ekaterina

This research aimed to study the potential for breaking through object size limitations of current X-ray computed tomography (CT) systems by implementing a limited angle scanning technique. CT stands out among other industrial nondestructive inspection (NDI) methods due to its unique ability to perform 3D volumetric inspection, unmatched micro-focus resolution, and objectivity that allows for automated result interpretation. This work attempts to advance NDI technique to enable microstructural material characterization and structural diagnostics of composite structures, where object sizes often prohibit the application of full 360° CT. Even in situations where the objects can be accommodated within existing micro-CT configuration, achieving sufficient magnification along with full rotation may not be viable. An effort was therefore made to achieve high-resolution scans from projection datasets with limited angular coverage (less than 180°) by developing effective reconstruction algorithms in conjunction with robust scan acquisition procedures. Internal features of inspected objects barely distinguishable in a 2D X-ray radiograph can be enhanced by additional projections that are reconstructed to a stack of slices, dramatically improving depth perception, a technique referred to as digital tomosynthesis. Building on the success of state-of-the-art medical tomosynthesis systems, this work sought to explore the feasibility of this technique for composite structures in aerospace applications. The challenge lies in the fact that the slices generated in medical tomosynthesis are too thick for relevant industrial applications. In order to adapt this concept to composite structures, reconstruction algorithms were expanded by implementation of optimized iterative stochastic methods (capable of reducing noise and refining scan quality) which resulted in better depth perception. The optimal scan acquisition procedure paired with the improved reconstruction algorithm facilitated higher in-plane and depth resolution compared to the clinical application. The developed limited angle tomography technique was demonstrated to be able to detect practically significant manufacturing defects (voids) and structural damage (delaminations) critical to structural integrity of composite parts. Keeping in mind the intended real-world aerospace applications where objects often have virtually unlimited in-plane dimensions, the developed technique of partial scanning could potentially extend the versatility of CT-based inspection and enable game changing NDI systems.

Propagation and perception of bioluminescence: factors affecting counterillumination as a cryptic strategy.

PubMed

Johnsen, Sönke; Widder, Edith A; Mobley, Curtis D

2004-08-01

Many deep-sea species, particularly crustaceans, cephalopods, and fish, use photophores to illuminate their ventral surfaces and thus disguise their silhouettes from predators viewing them from below. This strategy has several potential limitations, two of which are examined here. First, a predator with acute vision may be able to detect the individual photophores on the ventral surface. Second, a predator may be able to detect any mismatch between the spectrum of the bioluminescence and that of the background light. The first limitation was examined by modeling the perceived images of the counterillumination of the squid Abralia veranyi and the myctophid fish Ceratoscopelus maderensis as a function of the distance and visual acuity of the viewer. The second limitation was addressed by measuring downwelling irradiance under moonlight and starlight and then modeling underwater spectra. Four water types were examined: coastal water at a depth of 5 m and oceanic water at 5, 210, and 800 m. The appearance of the counterillumination was more affected by the visual acuity of the viewer than by the clarity of the water, even at relatively large distances. Species with high visual acuity (0.11 degrees resolution) were able to distinguish the individual photophores of some counterilluminating signals at distances of several meters, thus breaking the camouflage. Depth and the presence or absence of moonlight strongly affected the spectrum of the background light, particularly near the surface. The increased variability near the surface was partially offset by the higher contrast attenuation at shallow depths, which reduced the sighting distance of mismatches. This research has implications for the study of spatial resolution, contrast sensitivity, and color discrimination in deep-sea visual systems.

Lyman Break Galaxies in the Hubble Ultra Deep Field through Deep U-Band Imaging

NASA Astrophysics Data System (ADS)

Rafelski, Marc; Wolfe, A. M.; Cooke, J.; Chen, H. W.; Armandroff, T. E.; Wirth, G. D.

2009-12-01

We introduce an extremely deep U-band image taken of the Hubble Ultra Deep Field (HUDF), with a one sigma depth of 30.7 mag arcsec-2 and a detection limiting magnitude of 28 mag arcsec-2. The observations were carried out on the Keck I telescope using the LRIS-B detector. The U-band image substantially improves the accuracy of photometric redshift measurements of faint galaxies in the HUDF at z=[2.5,3.5]. The U-band for these galaxies is attenuated by lyman limit absorption, allowing for more reliable selections of candidate Lyman Break Galaxies (LBGs) than from photometric redshifts without U-band. We present a reliable sample of 300 LBGs at z=[2.5,3.5] in the HUDF. Accurate redshifts of faint galaxies at z=[2.5,3.5] are needed to obtain empirical constraints on the star formation efficiency of neutral gas at high redshift. Wolfe & Chen (2006) showed that the star formation rate (SFR) density in damped Ly-alpha absorption systems (DLAs) at z=[2.5,3.5] is significantly lower than predicted by the Kennicutt-Schmidt law for nearby galaxies. One caveat to this result that we wish to test is whether LBGs are embedded in DLAs. If in-situ star formation is occurring in DLAs, we would see it as extended low surface brightness emission around LBGs. We shall use the more accurate photometric redshifts to create a sample of LBGs around which we will look for extended emission in the more sensitive and higher resolution HUDF images. The absence of extended emission would put limits on the SFR density of DLAs associated with LBGs at high redshift. On the other hand, detection of faint emission on scales large compared to the bright LBG cores would indicate the presence of in situ star formation in those DLAs. Such gas would presumably fuel the higher star formation rates present in the LBG cores.

Criteria for Evaluating Coastal Flood-Protection Structures

DTIC Science & Technology

1989-12-01

Hotta, S., and Marui , N. 1976. "Local Scour and Current Around a Porous Breakwater," Chapter 93, Proceedings, 15th Coastal Engineering Conference, 11- 17...breaking waves consistent with FEMA depth-limited breaking wave approach to design. 7. Hotta and Marui (1976) testing permeable and impermeable shore

RPA Mediates Recruitment of MRX to Forks and Double-Strand Breaks to Hold Sister Chromatids Together.

PubMed

Seeber, Andrew; Hegnauer, Anna Maria; Hustedt, Nicole; Deshpande, Ishan; Poli, Jérôme; Eglinger, Jan; Pasero, Philippe; Gut, Heinz; Shinohara, Miki; Hopfner, Karl-Peter; Shimada, Kenji; Gasser, Susan M

2016-12-01

The Mre11-Rad50-Xrs2 (MRX) complex is related to SMC complexes that form rings capable of holding two distinct DNA strands together. MRX functions at stalled replication forks and double-strand breaks (DSBs). A mutation in the N-terminal OB fold of the 70 kDa subunit of yeast replication protein A, rfa1-t11, abrogates MRX recruitment to both types of DNA damage. The rfa1 mutation is functionally epistatic with loss of any of the MRX subunits for survival of replication fork stress or DSB recovery, although it does not compromise end-resection. High-resolution imaging shows that either the rfa1-t11 or the rad50Δ mutation lets stalled replication forks collapse and allows the separation not only of opposing ends but of sister chromatids at breaks. Given that cohesin loss does not provoke visible sister separation as long as the RPA-MRX contacts are intact, we conclude that MRX also serves as a structural linchpin holding sister chromatids together at breaks. Copyright © 2016 Elsevier Inc. All rights reserved.

The transcription fidelity factor GreA impedes DNA break repair.

PubMed

Sivaramakrishnan, Priya; Sepúlveda, Leonardo A; Halliday, Jennifer A; Liu, Jingjing; Núñez, María Angélica Bravo; Golding, Ido; Rosenberg, Susan M; Herman, Christophe

2017-10-12

Homologous recombination repairs DNA double-strand breaks and must function even on actively transcribed DNA. Because break repair prevents chromosome loss, the completion of repair is expected to outweigh the transcription of broken templates. However, the interplay between DNA break repair and transcription processivity is unclear. Here we show that the transcription factor GreA inhibits break repair in Escherichia coli. GreA restarts backtracked RNA polymerase and hence promotes transcription fidelity. We report that removal of GreA results in markedly enhanced break repair via the classic RecBCD-RecA pathway. Using a deep-sequencing method to measure chromosomal exonucleolytic degradation, we demonstrate that the absence of GreA limits RecBCD-mediated resection. Our findings suggest that increased RNA polymerase backtracking promotes break repair by instigating RecA loading by RecBCD, without the influence of canonical Chi signals. The idea that backtracked RNA polymerase can stimulate recombination presents a DNA transaction conundrum: a transcription fidelity factor that compromises genomic integrity.

Solute segregation and deviation from bulk thermodynamics at nanoscale crystalline defects.

PubMed

Titus, Michael S; Rhein, Robert K; Wells, Peter B; Dodge, Philip C; Viswanathan, Gopal Babu; Mills, Michael J; Van der Ven, Anton; Pollock, Tresa M

2016-12-01

It has long been known that solute segregation at crystalline defects can have profound effects on material properties. Nevertheless, quantifying the extent of solute segregation at nanoscale defects has proven challenging due to experimental limitations. A combined experimental and first-principles approach has been used to study solute segregation at extended intermetallic phases ranging from 4 to 35 atomic layers in thickness. Chemical mapping by both atom probe tomography and high-resolution scanning transmission electron microscopy demonstrates a markedly different composition for the 4-atomic-layer-thick phase, where segregation has occurred, compared to the approximately 35-atomic-layer-thick bulk phase of the same crystal structure. First-principles predictions of bulk free energies in conjunction with direct atomistic simulations of the intermetallic structure and chemistry demonstrate the breakdown of bulk thermodynamics at nanometer dimensions and highlight the importance of symmetry breaking due to the proximity of interfaces in determining equilibrium properties.

Solute segregation and deviation from bulk thermodynamics at nanoscale crystalline defects

PubMed Central

Titus, Michael S.; Rhein, Robert K.; Wells, Peter B.; Dodge, Philip C.; Viswanathan, Gopal Babu; Mills, Michael J.; Van der Ven, Anton; Pollock, Tresa M.

2016-01-01

It has long been known that solute segregation at crystalline defects can have profound effects on material properties. Nevertheless, quantifying the extent of solute segregation at nanoscale defects has proven challenging due to experimental limitations. A combined experimental and first-principles approach has been used to study solute segregation at extended intermetallic phases ranging from 4 to 35 atomic layers in thickness. Chemical mapping by both atom probe tomography and high-resolution scanning transmission electron microscopy demonstrates a markedly different composition for the 4–atomic-layer–thick phase, where segregation has occurred, compared to the approximately 35–atomic-layer–thick bulk phase of the same crystal structure. First-principles predictions of bulk free energies in conjunction with direct atomistic simulations of the intermetallic structure and chemistry demonstrate the breakdown of bulk thermodynamics at nanometer dimensions and highlight the importance of symmetry breaking due to the proximity of interfaces in determining equilibrium properties. PMID:28028543

The gamma-ray spectrum of Centaurus A - A high-resolution observation between 70 keV and 8 MeV

NASA Technical Reports Server (NTRS)

Gehrels, N.; Cline, T. L.; Teegarden, B. J.; Paciesas, W. S.; Tueller, J.; Durouchoux, PH.; Hameury, J. M.

1984-01-01

The NASA/Goddard Space Flight Center Low Energy Energy Gamma ray Spectrometer (LEGS) observed the nearby active nucleus galaxy Centaurus A (NGC 5128) during a balloon flight on 1981 November 19. There is no evidence of a break in the spectrum or of any line features. The 1.6 MeV limit is a factor of 8 lower than the 1974 line flux, indicating that, if the 1974 feature was real, and, if it was narrow, then the line intensity decreased significantly between 1974 and 1981. The lack of observed annihilation radiation from Cen A, combined with the temporal variations that are seen in the X-ray and gamma-ray intensities, constrain the size of the emission region to be between 10 to the 13th power and 5 x 10 to the 17th power cm. Previously announced in STAR as N83-35990

Octet baryon masses and sigma terms from an SU(3) chiral extrapolation

NASA Astrophysics Data System (ADS)

Young, R. D.; Thomas, A. W.

2010-01-01

We report an analysis of the impressive new lattice simulation results for octet baryon masses in 2+1-flavor QCD. The analysis is based on a low-order expansion about the chiral SU(3) limit in which the symmetry breaking arises from terms linear in the quark masses plus the variation of the Goldstone boson masses in the leading chiral loops. The baryon masses evaluated at the physical light-quark masses are in remarkable agreement with the experimental values, with a model dependence considerably smaller than the rather small statistical uncertainty. From the mass formulas one can evaluate the sigma commutators for all octet baryons. This yields an accurate value for the pion-nucleon sigma commutator. It also yields the first determination of the strangeness sigma term based on 2+1-flavor lattice QCD and, in general, the sigma commutators provide a resolution to the difficult issue of fine-tuning the strange-quark mass.

Comparisons between conventional optical imaging and parametric indirect microscopic imaging on human skin detection

NASA Astrophysics Data System (ADS)

Liu, Guoyan; Gao, Kun; Liu, Xuefeng; Ni, Guoqiang

2016-10-01

We report a new method, polarization parameters indirect microscopic imaging with a high transmission infrared light source, to detect the morphology and component of human skin. A conventional reflection microscopic system is used as the basic optical system, into which a polarization-modulation mechanics is inserted and a high transmission infrared light source is utilized. The near-field structural characteristics of human skin can be delivered by infrared waves and material coupling. According to coupling and conduction physics, changes of the optical wave parameters can be calculated and curves of the intensity of the image can be obtained. By analyzing the near-field polarization parameters in nanoscale, we can finally get the inversion images of human skin. Compared with the conventional direct optical microscope, this method can break diffraction limit and achieve a super resolution of sub-100nm. Besides, the method is more sensitive to the edges, wrinkles, boundaries and impurity particles.

Where size does matter: foldable telescope design for microsat application

NASA Astrophysics Data System (ADS)

Segert, Tom; Danziger, Björn; Lieder, Matthias

2017-11-01

The DOBSON SPACE TELESCOPE Project (DST) at the Technical University of Berlin (TUB) believes that micro satellites can be a challenging competitor in the high resolution remote sensing market. Using a micro satellite as basis for a remote sensing platform will dramatically reduce the cost for the end users thereby initiating the predicted remote sensing boom. The Challenging task is that an optic required for a GSD smaller than 1m is much bigger than the given room for secondary payload. In order to break the volume limits of hitchhiker payloads the DST team develops an optical telescope with deployable structures. The core piece of DST is a 20 inch modified Cassegrain optic. Stored during ascend the instrument fits in a box measuring 60 x 60 x 30cm (including telescope and optical plane assembly). After the satellite was released into free space the telescope unfolds and collimates automatically.

Configurational entropy measurements in extremely supercooled liquids that break the glass ceiling.

PubMed

Berthier, Ludovic; Charbonneau, Patrick; Coslovich, Daniele; Ninarello, Andrea; Ozawa, Misaki; Yaida, Sho

2017-10-24

Liquids relax extremely slowly on approaching the glass state. One explanation is that an entropy crisis, because of the rarefaction of available states, makes it increasingly arduous to reach equilibrium in that regime. Validating this scenario is challenging, because experiments offer limited resolution, while numerical studies lag more than eight orders of magnitude behind experimentally relevant timescales. In this work, we not only close the colossal gap between experiments and simulations but manage to create in silico configurations that have no experimental analog yet. Deploying a range of computational tools, we obtain four estimates of their configurational entropy. These measurements consistently confirm that the steep entropy decrease observed in experiments is also found in simulations, even beyond the experimental glass transition. Our numerical results thus extend the observational window into the physics of glasses and reinforce the relevance of an entropy crisis for understanding their formation. Published under the PNAS license.

Breaking the glass ceiling: Configurational entropy measurements in extremely supercooled liquids

NASA Astrophysics Data System (ADS)

Berthier, Ludovic

Liquids relax extremely slowly on approaching the glass state. One explanation is that an entropy crisis, due to the rarefaction of available states, makes it increasingly arduous to reach equilibrium in that regime. Validating this scenario is challenging, because experiments offer limited resolution, while numerical studies lag more than eight orders of magnitude behind experimentally-relevant timescales. In this work we not only close the colossal gap between experiments and simulations but manage to create in-silico configurations that have no experimental analog yet. Deploying a range of computational tools, we obtain four independent estimates of their configurational entropy. These measurements consistently indicate that the steep entropy decrease observed in experiments is found in simulations even beyond the experimental glass transition. Our numerical results thus open a new observational window into the physics of glasses and reinforce the relevance of an entropy crisis for understanding their formation.

Configurational entropy measurements in extremely supercooled liquids that break the glass ceiling

PubMed Central

Berthier, Ludovic; Charbonneau, Patrick; Coslovich, Daniele; Ninarello, Andrea; Ozawa, Misaki

2017-01-01

Liquids relax extremely slowly on approaching the glass state. One explanation is that an entropy crisis, because of the rarefaction of available states, makes it increasingly arduous to reach equilibrium in that regime. Validating this scenario is challenging, because experiments offer limited resolution, while numerical studies lag more than eight orders of magnitude behind experimentally relevant timescales. In this work, we not only close the colossal gap between experiments and simulations but manage to create in silico configurations that have no experimental analog yet. Deploying a range of computational tools, we obtain four estimates of their configurational entropy. These measurements consistently confirm that the steep entropy decrease observed in experiments is also found in simulations, even beyond the experimental glass transition. Our numerical results thus extend the observational window into the physics of glasses and reinforce the relevance of an entropy crisis for understanding their formation. PMID:29073056

The gamma-ray spectrum of Centaurus A: A high-resolution observation between 70 keV and 8 MeV

NASA Technical Reports Server (NTRS)

Gehrels, N.; Cline, T. L.; Teegarden, B. J.; Paciesas, W. S.; Tueller, J.; Durouchoux, P.; Hameury, J. M.

1983-01-01

The NASA/Goddard Space Flight Center Low Energy Gamma ray Spectrometer (LEGS) observed the nearby active nucleus galaxy Centaurus A (NGC 5128) during a balloon flight on 1981 November 19. There is no evidence of a break in the spectrum or of any line features. The 1.6 MeV limit is a factor of 8 lower than the 1974 line flux, indicating that, if the 1974 feature was real, and, if it was narrow, then the line intensity decreased significantly between 1974 and 1981. The lack of observed annihilation radiation from Cen A, combined with the temporal variations that are seen in the X-ray and gamma-ray intensities, constrain the size of the emission region to be between 10 to the 13th power and 5 x 10 to the 17th power cm.

Configurational entropy measurements in extremely supercooled liquids that break the glass ceiling

NASA Astrophysics Data System (ADS)

Berthier, Ludovic; Charbonneau, Patrick; Coslovich, Daniele; Ninarello, Andrea; Ozawa, Misaki; Yaida, Sho

2017-10-01

Liquids relax extremely slowly on approaching the glass state. One explanation is that an entropy crisis, because of the rarefaction of available states, makes it increasingly arduous to reach equilibrium in that regime. Validating this scenario is challenging, because experiments offer limited resolution, while numerical studies lag more than eight orders of magnitude behind experimentally relevant timescales. In this work, we not only close the colossal gap between experiments and simulations but manage to create in silico configurations that have no experimental analog yet. Deploying a range of computational tools, we obtain four estimates of their configurational entropy. These measurements consistently confirm that the steep entropy decrease observed in experiments is also found in simulations, even beyond the experimental glass transition. Our numerical results thus extend the observational window into the physics of glasses and reinforce the relevance of an entropy crisis for understanding their formation.

Snowmelt Pattern and Lake Ice Phenology around Tibetan Plateau Estimated from Enhanced Resolution Passive Microwave Data

NASA Astrophysics Data System (ADS)

Xiong, C.; Shi, J.; Wang, T.

2017-12-01

Snow and ice is very sensitive to the climate change. Rising air temperature will cause the snowmelt time change. In contrast, the change in snow state will have feedback on climate through snow albedo. The snow melt timing is also correlated with the associated runoff. Ice phenology describes the seasonal cycle of lake ice cover and includes freeze-up and breakup periods and ice cover duration, which is an important weather and climate indicator. It is also important for lake-atmosphere interactions and hydrological and ecological processes. The enhanced resolution (up to 3.125 km) passive microwave data is used to estimate the snowmelt pattern and lake ice phenology on and around Tibetan Plateau. The enhanced resolution makes the estimation of snowmelt and lake ice phenology in more spatial detail compared to previous 25 km gridded passive microwave data. New algorithm based on smooth filters and change point detection was developed to estimate the snowmelt and lake ice freeze-up and break-up timing. Spatial and temporal pattern of snowmelt and lake ice phonology are estimated. This study provides an objective evidence of climate change impact on the cryospheric system on Tibetan Plateau. The results show significant earlier snowmelt and lake ice break-up in some regions.

Breaking the GaN material limits with nanoscale vertical polarisation super junction structures: A simulation analysis

NASA Astrophysics Data System (ADS)

Unni, Vineet; Sankara Narayanan, E. M.

2017-04-01

This is the first report on the numerical analysis of the performance of nanoscale vertical superjunction structures based on impurity doping and an innovative approach that utilizes the polarisation properties inherent in III-V nitride semiconductors. Such nanoscale vertical polarisation super junction structures can be realized by employing a combination of epitaxial growth along the non-polar crystallographic axes of Wurtzite GaN and nanolithography-based processing techniques. Detailed numerical simulations clearly highlight the limitations of a doping based approach and the advantages of the proposed solution for breaking the unipolar one-dimensional material limits of GaN by orders of magnitude.

Future summer mega-heatwave and record-breaking temperatures in a warmer France climate

NASA Astrophysics Data System (ADS)

Bador, Margot; Terray, Laurent; Boé, Julien; Somot, Samuel; Alias, Antoinette; Gibelin, Anne-Laure; Dubuisson, Brigitte

2017-07-01

This study focuses on future very hot summers associated with severe heatwaves and record-breaking temperatures in France. Daily temperature observations and a pair of historical and scenario (greenhouse gas radiative concentration pathway 8.5) simulations with the high-resolution (∼12.5 km) ALADIN regional climate model provide a robust framework to examine the spatial distribution of these extreme events and their 21st century evolution. Five regions are identified with an extreme event spatial clustering algorithm applied to observed temperatures. They are used to diagnose the 21st century heatwave spatial patterns. In the 2070s, we find a simulated mega-heatwave as severe as the 2003 observed heatwave relative to its contemporaneous climate. A 20-member initial condition ensemble is used to assess the sensitivity of this future heatwave to the internal variability in the regional climate model and to pre-existing land surface conditions. Even in a much warmer and drier climate in France, late spring dry land conditions may lead to a significant amplification of summer extreme temperatures and heatwave intensity through limitations in evapotranspiration. By 2100, the increase in summer temperature maxima exhibits a range from 6 °C to almost 13 °C in the five regions in France, relative to historical maxima. These projections are comparable with the estimates given by a large number of global climate models.

Impact of high resolution land surface initialization in Indian summer monsoon simulation using a regional climate model

NASA Astrophysics Data System (ADS)

Unnikrishnan, C. K.; Rajeevan, M.; Rao, S. Vijaya Bhaskara

2016-06-01

The direct impact of high resolution land surface initialization on the forecast bias in a regional climate model in recent years over Indian summer monsoon region is investigated. Two sets of regional climate model simulations are performed, one with a coarse resolution land surface initial conditions and second one used a high resolution land surface data for initial condition. The results show that all monsoon years respond differently to the high resolution land surface initialization. The drought monsoon year 2009 and extended break periods were more sensitive to the high resolution land surface initialization. These results suggest that the drought monsoon year predictions can be improved with high resolution land surface initialization. Result also shows that there are differences in the response to the land surface initialization within the monsoon season. Case studies of heat wave and a monsoon depression simulation show that, the model biases were also improved with high resolution land surface initialization. These results show the need for a better land surface initialization strategy in high resolution regional models for monsoon forecasting.

Gamma-Ray Burst Jet Breaks Revisited

NASA Astrophysics Data System (ADS)

Wang, Xiang-Gao; Zhang, Bing; Liang, En-Wei; Lu, Rui-Jing; Lin, Da-Bin; Li, Jing; Li, Long

2018-06-01

Gamma-ray Burst (GRB) collimation has been inferred with the observations of achromatic steepening in GRB light curves, known as jet breaks. Identifying a jet break from a GRB afterglow light curve allows a measurement of the jet opening angle and true energetics of GRBs. In this paper, we re-investigate this problem using a large sample of GRBs that have an optical jet break that is consistent with being achromatic in the X-ray band. Our sample includes 99 GRBs from 1997 February to 2015 March that have optical and, for Swift GRBs, X-ray light curves that are consistent with the jet break interpretation. Out of the 99 GRBs we have studied, 55 GRBs are found to have temporal and spectral behaviors both before and after the break, consistent with the theoretical predictions of the jet break models, respectively. These include 53 long/soft (Type II) and 2 short/hard (Type I) GRBs. Only 1 GRB is classified as the candidate of a jet break with energy injection. Another 41 and 3 GRBs are classified as the candidates with the lower and upper limits of the jet break time, respectively. Most jet breaks occur at 90 ks, with a typical opening angle θj = (2.5 ± 1.0)°. This gives a typical beaming correction factor {f}b-1∼ 1000 for Type II GRBs, suggesting an even higher total GRB event rate density in the universe. Both isotropic and jet-corrected energies have a wide span in their distributions: log(Eγ,iso/erg) = 53.11 with σ = 0.84 log(EK,iso/erg) = 54.82 with σ = 0.56 log(Eγ/erg) = 49.54 with σ = 1.29 and log(EK/erg) = 51.33 with σ = 0.58. We also investigate several empirical correlations (Amati, Frail, Ghirlanda, and Liang–Zhang) previously discussed in the literature. We find that in general most of these relations are less tight than before. The existence of early jet breaks and hence small opening angle jets, which were detected in the Swfit era, is most likely the source of scatter. If one limits the sample to jet breaks later than 104 s, the Liang–Zhang relation remains tight and the Ghirlanda relation still exists. These relations are derived from Type II GRBs, and Type I GRBs usually deviate from them.

Impact of thoracic surgery on esophageal motor function—Evaluation by high resolution manometry

PubMed Central

Kandulski, Arne; Malfertheiner, Peter; Riedel, Sandra; Zardo, Patrick; Hachenberg, Thomas; Schreiber, Jens

2017-01-01

Background Alteration of esophageal function is a potential risk factor for postoperative complications in thoracic surgery. This prospective study investigates esophageal motility and function during and after thoracic procedures via high resolution manometry (HRM) and impedance technology with spatiotemporal representation of pressure data. Methods Twelve consecutive patients eligible for elective thoracic surgery underwent preoperative and postoperative (48 hours and 7 days) esophageal HRM. Swallowing acts were carried out with 5 mL of water, 10 mL of water and 1 cm3 bread in physiological posture to evaluate distal contraction integral (DCI). Length and location of contractile integrity breaks were measured by investigators blinded to the form of surgical intervention. The impact of surgical procedures on esophageal motility was quantified according to current Chicago Classification (CC) criteria. Pre-, intra- and postoperative 24-hour multi-channel impedance pH–metry (MII-pH) was performed to further analyze gastroesophageal reflux patterns. Results All patients were investigated 48 hours prior to and 7 days after thoracic procedures, with a total of n=675 swallowing acts being included in our study. Increased motility patterns of the tubular esophagus occurred temporally 48 hours postoperatively. DCI 48 hours after surgery increased significantly (5 mL, P=0.049; solid, P=0.014) and returned to baseline values after seven days (5 mL, P=0.039; solid, P=0.039). Break length was significantly reduced 48 hours postoperatively, especially in the proximal esophageal segment (transition zone). Follow-up measurements after another week were comparable to preoperative baseline findings. The perioperative MII-pH measurement showed numerous artifacts caused by intubation and ventilation during surgery also with increasing short and frequent acidic reflux episodes. Conclusions Thoracic procedures cause a transient modulation of esophageal peristalsis with postoperative increased contractility of the tubular esophagus, presumably without affecting intraesophageal reflex arcs. Although limited by the number of patients, we can conclude on our data that postoperative esophageal hypomotility is unlikely to promote secondary pulmonary complications. PMID:28740669

Impact of thoracic surgery on esophageal motor function-Evaluation by high resolution manometry.

PubMed

Wäsche, Anja; Kandulski, Arne; Malfertheiner, Peter; Riedel, Sandra; Zardo, Patrick; Hachenberg, Thomas; Schreiber, Jens

2017-06-01

Alteration of esophageal function is a potential risk factor for postoperative complications in thoracic surgery. This prospective study investigates esophageal motility and function during and after thoracic procedures via high resolution manometry (HRM) and impedance technology with spatiotemporal representation of pressure data. Twelve consecutive patients eligible for elective thoracic surgery underwent preoperative and postoperative (48 hours and 7 days) esophageal HRM. Swallowing acts were carried out with 5 mL of water, 10 mL of water and 1 cm 3 bread in physiological posture to evaluate distal contraction integral (DCI). Length and location of contractile integrity breaks were measured by investigators blinded to the form of surgical intervention. The impact of surgical procedures on esophageal motility was quantified according to current Chicago Classification (CC) criteria. Pre-, intra- and postoperative 24-hour multi-channel impedance pH-metry (MII-pH) was performed to further analyze gastroesophageal reflux patterns. All patients were investigated 48 hours prior to and 7 days after thoracic procedures, with a total of n=675 swallowing acts being included in our study. Increased motility patterns of the tubular esophagus occurred temporally 48 hours postoperatively. DCI 48 hours after surgery increased significantly (5 mL, P=0.049; solid, P=0.014) and returned to baseline values after seven days (5 mL, P=0.039; solid, P=0.039). Break length was significantly reduced 48 hours postoperatively, especially in the proximal esophageal segment (transition zone). Follow-up measurements after another week were comparable to preoperative baseline findings. The perioperative MII-pH measurement showed numerous artifacts caused by intubation and ventilation during surgery also with increasing short and frequent acidic reflux episodes. Thoracic procedures cause a transient modulation of esophageal peristalsis with postoperative increased contractility of the tubular esophagus, presumably without affecting intraesophageal reflex arcs. Although limited by the number of patients, we can conclude on our data that postoperative esophageal hypomotility is unlikely to promote secondary pulmonary complications.

Observation of the Λ⁷He Hypernucleus by the (e, e'K⁺) Reaction

DOE PAGES

Nakamura, S. N.; Matsumura, A.; Okayasu, Y.; ...

2013-01-02

An experiment with a newly developed high-resolution kaon spectrometer and a scattered electron spectrometer with a novel configuration was performed in Hall C at Jefferson Lab. The ground state of a neutron-rich hypernucleus, He Λ⁷, was observed for the first time with the (e, e'K⁺) reaction with an energy resolution of ~0.6 MeV. This resolution is the best reported to date for hypernuclear reaction spectroscopy. The He Λ⁷ binding energy supplies the last missing information of the A=7, T=1 hypernuclear isotriplet, providing a new input for the charge symmetry breaking effect of the ΛN potential.

A longitudinal study of the associations among adolescent conflict resolution styles, depressive symptoms, and romantic relationship longevity.

PubMed

Ha, Thao; Overbeek, Geertjan; Cillessen, Antonius H N; Engels, Rutger C M E

2012-10-01

This study investigated whether adolescents' conflict resolution styles mediated between depressive symptoms and relationship longevity. Data were used from a sample of 80 couples aged 13-19 years old (Mage = 15.48, SD = 1.16). At Time 1 adolescents reported their depressive symptoms and conflict resolution styles. Additionally, time until break-up was assessed. Data were analyzed using actor-partner interdependence models. Results showed no support for conflict resolution styles as mediators. Girls' depressive symptoms were directly related to shorter relationships. Additionally, actor effects were found indicating that boys and girls with more depressive symptoms used negative resolution styles and were less likely to employ positive problems solving strategies. Finally, one partner effect was found: girls' depressive symptoms related to more positive problem solving in boys. Copyright © 2012 The Foundation for Professionals in Services for Adolescents. Published by Elsevier Ltd. All rights reserved.

Century long observation constrained global dynamic downscaling and hydrologic implication

NASA Astrophysics Data System (ADS)

Kim, H.; Yoshimura, K.; Chang, E.; Famiglietti, J. S.; Oki, T.

2012-12-01

It has been suggested that greenhouse gas induced warming climate causes the acceleration of large scale hydrologic cycles, and, indeed, many regions on the Earth have been suffered by hydrologic extremes getting more frequent. However, historical observations are not able to provide enough information in comprehensive manner to understand their long-term variability and/or global distributions. In this study, a century long high resolution global climate data is developed in order to break through existing limitations. 20th Century Reanalysis (20CR) which has relatively low spatial resolution (~2.0°) and longer term availability (140 years) is dynamically downscaled into global T248 (~0.5°) resolution using Experimental Climate Prediction Center (ECPC) Global Spectral Model (GSM) by spectral nudging data assimilation technique. Also, Global Precipitation Climatology Centre (GPCC) and Climate Research Unit (CRU) observational data are adopted to reduce model dependent uncertainty. Downscaled product successfully represents realistic geographical detail keeping low frequency signal in mean state and spatiotemporal variability, while previous bias correction method fails to reproduce high frequency variability. Newly developed data is used to investigate how long-term large scale terrestrial hydrologic cycles have been changed globally and how they have been interacted with various climate modes, such as El-Niño Southern Oscillation (ENSO) and Atlantic Multidecadal Oscillation (AMO). As a further application, it will be used to provide atmospheric boundary condition of multiple land surface models in the Global Soil Wetness Project Phase 3 (GSWP3).

HerMES: ALMA Imaging of Herschel-selected Dusty Star-forming Galaxies

NASA Astrophysics Data System (ADS)

Bussmann, R. S.; Riechers, D.; Fialkov, A.; Scudder, J.; Hayward, C. C.; Cowley, W. I.; Bock, J.; Calanog, J.; Chapman, S. C.; Cooray, A.; De Bernardis, F.; Farrah, D.; Fu, Hai; Gavazzi, R.; Hopwood, R.; Ivison, R. J.; Jarvis, M.; Lacey, C.; Loeb, A.; Oliver, S. J.; Pérez-Fournon, I.; Rigopoulou, D.; Roseboom, I. G.; Scott, Douglas; Smith, A. J.; Vieira, J. D.; Wang, L.; Wardlow, J.

2015-10-01

The Herschel Multi-tiered Extragalactic Survey (HerMES) has identified large numbers of dusty star-forming galaxies (DSFGs) over a wide range in redshift. A detailed understanding of these DSFGs is hampered by the limited spatial resolution of Herschel. We present 870 μm 0.″45 resolution imaging obtained with the Atacama Large Millimeter/submillimeter Array (ALMA) of a sample of 29 HerMES DSFGs that have far-infrared (FIR) flux densities that lie between the brightest of sources found by Herschel and fainter DSFGs found via ground-based surveys in the submillimeter region. The ALMA imaging reveals that these DSFGs comprise a total of 62 sources (down to the 5σ point-source sensitivity limit in our ALMA sample; σ ≈ 0.2 {mJy}). Optical or near-infrared imaging indicates that 36 of the ALMA sources experience a significant flux boost from gravitational lensing (μ \\gt 1.1), but only six are strongly lensed and show multiple images. We introduce and make use of uvmcmcfit, a general-purpose and publicly available Markov chain Monte Carlo visibility-plane analysis tool to analyze the source properties. Combined with our previous work on brighter Herschel sources, the lens models presented here tentatively favor intrinsic number counts for DSFGs with a break near 8 {mJy} at 880 μ {{m}} and a steep fall-off at higher flux densities. Nearly 70% of the Herschel sources break down into multiple ALMA counterparts, consistent with previous research indicating that the multiplicity rate is high in bright sources discovered in single-dish submillimeter or FIR surveys. The ALMA counterparts to our Herschel targets are located significantly closer to each other than ALMA counterparts to sources found in the LABOCA ECDFS Submillimeter Survey. Theoretical models underpredict the excess number of sources with small separations seen in our ALMA sample. The high multiplicity rate and small projected separations between sources seen in our sample argue in favor of interactions and mergers plausibly driving both the prodigious emission from the brightest DSFGs as well as the sharp downturn above {S}880=8 {mJy}. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA.

Kinetics of protein–ligand unbinding: Predicting pathways, rates, and rate-limiting steps

PubMed Central

Tiwary, Pratyush; Limongelli, Vittorio; Salvalaglio, Matteo; Parrinello, Michele

2015-01-01

The ability to predict the mechanisms and the associated rate constants of protein–ligand unbinding is of great practical importance in drug design. In this work we demonstrate how a recently introduced metadynamics-based approach allows exploration of the unbinding pathways, estimation of the rates, and determination of the rate-limiting steps in the paradigmatic case of the trypsin–benzamidine system. Protein, ligand, and solvent are described with full atomic resolution. Using metadynamics, multiple unbinding trajectories that start with the ligand in the crystallographic binding pose and end with the ligand in the fully solvated state are generated. The unbinding rate koff is computed from the mean residence time of the ligand. Using our previously computed binding affinity we also obtain the binding rate kon. Both rates are in agreement with reported experimental values. We uncover the complex pathways of unbinding trajectories and describe the critical rate-limiting steps with unprecedented detail. Our findings illuminate the role played by the coupling between subtle protein backbone fluctuations and the solvation by water molecules that enter the binding pocket and assist in the breaking of the shielded hydrogen bonds. We expect our approach to be useful in calculating rates for general protein–ligand systems and a valid support for drug design. PMID:25605901

Search for diphoton events with large missing transverse momentum in 1 fb(-1) of 7 TeV proton-proton collision data with the ATLAS detector

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

Aad G.; Abbott B.; Abdallah J.

2012-04-20

A search for diphoton events with large missing transverse momentum has been performed using 1.07 fb{sup -1} of proton-proton collision data at {radical}s = 7 TeV recorded with the ATLAS detector. No excess of events was observed above the Standard Model prediction and 95% Confidence Level (CL) upper limits are set on the production cross section for new physics. The limits depend on each model parameter space and vary as follows: {sigma} < (22-129) fb in the context of a generalized model of gauge-mediated supersymmetry breaking (GGM) with a bino-like lightest neutralino, {sigma} < (27-91) fb in the context ofmore » a minimal model of gauge-mediated supersymmetry breaking (SPS8), and {sigma} < (15-27) fb in the context of a specific model with one universal extra dimension (UED). A 95% CL lower limit of 805 GeV, for bino masses above 50 GeV, is set on the GGM gluino mass. Lower limits of 145 TeV and 1.23 TeV are set on the SPS8 breaking scale {Lambda} and on the UED compactification scale 1/R, respectively. These limits provide the most stringent tests of these models to date.« less

Search for diphoton events with large missing transverse momentum in 1 fb - 1 of 7 TeV proton–proton collision data with the ATLAS detector

DOE PAGES

Aad, G.; Abbott, B.; Abdallah, J.; ...

2012-02-22

A search for diphoton events with large missing transverse momentum has been performed using 1.07fb -1 of proton–proton collision data at s=7TeV recorded with the ATLAS detector. No excess of events was observed above the Standard Model prediction and 95% Confidence Level (CL) upper limits are set on the production cross section for new physics. The limits depend on each model parameter space and vary as follows: σ<(22–129)fb in the context of a generalised model of gauge-mediated supersymmetry breaking (GGM) with a bino-like lightest neutralino, σ<(27–91)fb in the context of a minimal model of gauge-mediated supersymmetry breaking (SPS8), and σ<(15–27)fbmore » in the context of a specific model with one universal extra dimension (UED). A 95% CL lower limit of 805GeV, for bino masses above 50 GeV, is set on the GGM gluino mass. Lower limits of 145TeV and 1.23TeV are set on the SPS8 breaking scale Λ and on the UED compactification scale 1/R, respectively. These limits provide the most stringent tests of these models to date.« less

Dynamical Lorentz symmetry breaking in 3D and charge fractionalization

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

Charneski, B.; Gomes, M.; Silva, A. J. da

2009-03-15

We analyze the breaking of Lorentz invariance in a 3D model of fermion fields self-coupled through four-fermion interactions. The low-energy limit of the theory contains various submodels which are similar to those used in the study of graphene or in the description of irrational charge fractionalization.

Exploiting Tumor Activated Testes Proteins To Enhance Efficacy of First Line Chemotherapeutics in NSCLC

DTIC Science & Technology

2016-10-01

Antigen (CTA), Fanconia- Anemia (FA), DNA Damage, Genomic Instability, DNA Double Strand Break (DSB) 16. SECURITY CLASSIFICATION OF: 17. LIMITATION...Fanconia- Anemia (FA) o DNA Damage o Genomic Instability o DNA Double Strand Break (DSB) 3. Accomplishments • What were the major goals and objectives of

Physical Activity Breaks and Facilities in US Secondary Schools

ERIC Educational Resources Information Center

Hood, Nancy E.; Colabianchi, Natalie; Terry-McElrath, Yvonne M.; O'Malley, Patrick M.; Johnston, Lloyd D.

2014-01-01

Background: Research on physical activity breaks and facilities (indoor and outdoor) in secondary schools is relatively limited. Methods: School administrators and students in nationally representative samples of 8th (middle school) and 10th/12th grade (high school) students were surveyed annually from 2008-2009 to 2011-2012. School administrators…

Effects of school breaks on influenza-like illness incidence in a temperate Chinese region: an ecological study from 2008 to 2015.

PubMed

Chu, Yanhui; Wu, Zhenyu; Ji, Jiayi; Sun, Jingyi; Sun, Xiaoyu; Qin, Guoyou; Qin, Jingning; Xiao, Zheng; Ren, Jian; Qin, Di; Zheng, Xueying; Wang, Xi-Ling

2017-03-06

To assess the effects of winter/summer school breaks on occurrences of influenza-like illness (ILI). We jointly analysed ILI surveillance data with the timing of school breaks in a temperate district in Beijing, China from 2008 to 2015. ILI incidence rate ratios (IRRs) of schoolchildren (5-14 and 15-24 years of age) to adults (25-59 and >60 years of age) were used to measure the age shift of ILI incidence before, during and after the 4-week winter/7-week summer breaks. Serfling-based Poisson regression model with adjustment for unmeasured confounders was built to further assess the effect of winter school breaks. ILI incidences were consistently lower during winter breaks than before winter breaks for all age groups. IRRs of younger schoolchildren aged 5-14 to adults were higher during winter school breaks than before breaks, while the opposite was true for the IRRs of older schoolchildren aged 15-24 to adults. Schoolchildren-to-adults IRRs during summer breaks were significantly lower than before or after school breaks (p<0.001). Both winter and summer breaks were associated with reductions of ILI incidences among schoolchildren and adults. Our study contributes additional evidence on the effects of school breaks on ILI incidence, suggesting school closure could be effective in controlling influenza transmission in developing countries. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/.

Nearshore bars and the break-point hypothesis

USGS Publications Warehouse

Sallenger, A.H.; Howd, P.A.

1989-01-01

The set of hypotheses calling for bar formation at the break point was tested with field data. During two different experiments, waves were measured across the surf zone coincident with the development of a nearshore bar. We use a criterion, based on the wave height to depth ratio, to determine the offshore limit of the inner surf zone. During the first experiment, the bar became better developed and migrated offshore while remaining well within the inner surf zone. During the second experiment, the surf zone was narrower and we cannot rule out the possibility of break point processes contributing to bar development. We conclude that bars are not necessarily coupled with the break point and can become better developed and migrate offshore while being in the inner surf zone landward from initial wave breaking in the outer surf zone. ?? 1989.

Toughening elastomers with sacrificial bonds and watching them break.

PubMed

Ducrot, Etienne; Chen, Yulan; Bulters, Markus; Sijbesma, Rint P; Creton, Costantino

2014-04-11

Elastomers are widely used because of their large-strain reversible deformability. Most unfilled elastomers suffer from a poor mechanical strength, which limits their use. Using sacrificial bonds, we show how brittle, unfilled elastomers can be strongly reinforced in stiffness and toughness (up to 4 megapascals and 9 kilojoules per square meter) by introducing a variable proportion of isotropically prestretched chains that can break and dissipate energy before the material fails. Chemoluminescent cross-linking molecules, which emit light as they break, map in real time where and when many of these internal bonds break ahead of a propagating crack. The simple methodology that we use to introduce sacrificial bonds, combined with the mapping of where bonds break, has the potential to stimulate the development of new classes of unfilled tough elastomers and better molecular models of the fracture of soft materials.

Water level effects on breaking wave setup for Pacific Island fringing reefs

NASA Astrophysics Data System (ADS)

Becker, J. M.; Merrifield, M. A.; Ford, M.

2014-02-01

The effects of water level variations on breaking wave setup over fringing reefs are assessed using field measurements obtained at three study sites in the Republic of the Marshall Islands and the Mariana Islands in the western tropical Pacific Ocean. At each site, reef flat setup varies over the tidal range with weaker setup at high tide and stronger setup at low tide for a given incident wave height. The observed water level dependence is interpreted in the context of radiation stress gradients specified by an idealized point break model generalized for nonnormally incident waves. The tidally varying setup is due in part to depth-limited wave heights on the reef flat, as anticipated from previous reef studies, but also to tidally dependent breaking on the reef face. The tidal dependence of the breaking is interpreted in the context of the point break model in terms of a tidally varying wave height to water depth ratio at breaking. Implications for predictions of wave-driven setup at reef-fringed island shorelines are discussed.

On the origin of increased sensitivity and mass resolution using silicon masks in MALDI.

PubMed

Diologent, Laurent; Franck, Julien; Wisztorski, Maxence; Treizebre, Anthony; Focsa, Cristian; Fournier, Isabelle; Ziskind, Michael

2014-02-04

Since its development, MALDI has proved its performance in the analysis of intact biomolecules up to high molecular weights, regardless of their polarity. Sensitivity of MALDI instruments is a key point for breaking the limits of observing biomolecules of lower abundances. Instrumentation is one way to improve sensitivity by increasing ion transmission and using more sensitive detection systems. On the other side, improving MALDI ion production yields would have important outcomes. MALDI ion production is still not well-controlled and, indeed, the amount of ions produced per laser shot with respect to the total volume of desorbed material is very low. This has particular implications for certain applications, such as MALDI MS imaging where laser beam focusing as fine as possible (5-10 μm) is searched in order to reach higher spatial resolution images. However, various studies point out an intrinsic decrease in signal intensity for strong focusing. We have therefore been interested in developing silicon mask systems to decrease an irradiated area by cutting rather than focusing the laser beam and to study the parameters affecting sensitivity using such systems. For this, we systematically examined variation with laser fluence of intensity and spectral resolution in MALDI of standard peptides when using silicon-etched masks of various aperture sizes. These studies demonstrate a simultaneous increase in spectral resolution and signal intensity. Origin of this effect is discussed in the frame of the two-step ionization model. Experimental data in the low fluence range are fitted with an increase of the primary ionization through matrix-silicon edge contact provided by the masks. On the other hand, behavior at higher fluence could be explained by an effect on the secondary ionization via changes in the plume dynamics.

Comparison and Computational Performance of Tsunami-HySEA and MOST Models for the LANTEX 2013 scenario

NASA Astrophysics Data System (ADS)

González-Vida, Jose M.; Macías, Jorge; Mercado, Aurelio; Ortega, Sergio; Castro, Manuel J.

2017-04-01

Tsunami-HySEA model is used to simulate the Caribbean LANTEX 2013 scenario (LANTEX is the acronym for Large AtlaNtic Tsunami EXercise, which is carried out annually). The numerical simulation of the propagation and inundation phases, is performed with both models but using different mesh resolutions and nested meshes. Some comparisons with the MOST tsunami model available at the University of Puerto Rico (UPR) are made. Both models compare well for propagating tsunami waves in open sea, producing very similar results. In near-shore shallow waters, Tsunami-HySEA should be compared with the inundation version of MOST, since the propagation version of MOST is limited to deeper waters. Regarding the inundation phase, a 1 arc-sec (approximately 30 m) resolution mesh covering all of Puerto Rico, is used, and a three-level nested meshes technique implemented. In the inundation phase, larger differences between model results are observed. Nevertheless, the most striking difference resides in computational time; Tsunami-HySEA is coded using the advantages of GPU architecture, and can produce a 4 h simulation in a 60 arcsec resolution grid for the whole Caribbean Sea in less than 4 min with a single general-purpose GPU and as fast as 11 s with 32 general-purpose GPUs. In the inundation stage with nested meshes, approximately 8 hours of wall clock time is needed for a 2-h simulation in a single GPU (versus more than 2 days for the MOST inundation, running three different parts of the island—West, Center, East—at the same time due to memory limitations in MOST). When domain decomposition techniques are finally implemented by breaking up the computational domain into sub-domains and assigning a GPU to each sub-domain (multi-GPU Tsunami-HySEA version), we show that the wall clock time significantly decreases, allowing high-resolution inundation modelling in very short computational times, reducing, for example, if eight GPUs are used, the wall clock time to around 1 hour. Besides, these computational times are obtained using general-purpose GPU hardware.

Temporal Variability in the Accretion Rate of Interplanetary Dust Using (3)He as a Tracer

NASA Technical Reports Server (NTRS)

Farley, K. A.

2005-01-01

The research supported by this grant falls under three topics: 1) Weekly Interplanetary Dust Sampling via (3)He; 2) Extraterrestrial (3)He at Major Impact Boundaries; 3) Completing a Moderately-High Resolution Record of Extraterrestrial (3)He Flux: A Major Asteroidal Break up Event at 8.2 Ma.

Characterization of Differential Toll-Like Receptor Responses below the Optical Diffraction Limit**

PubMed Central

Aaron, Jesse S.; Carson, Bryan D.; Timlin, Jerilyn A.

2013-01-01

Many membrane receptors are recruited to specific cell surface domains to form nanoscale clusters upon ligand activation. This step appears to be necessary to initiate signaling, including pathways in innate immune system activation. However, virulent pathogens such as Yersinia pestis (the causative agent of plague) are known to evade innate immune detection, in contrast to similar microbes (such as E. coli) that elicit a robust response. This disparity has been partly attributed to the structure of lipopolysaccharides (LPS) on the bacterial cell wall, which are recognized by the innate immune receptor TLR4. As such, we hypothesized that nanoscale differences would exist between the spatial clustering of TLR4 upon binding of LPS derived from Y. pestis and E. coli. Although optical imaging can provide exquisite details of the spatial organization of biomolecules, there is a mismatch between the scale at which receptor clustering occurs (<300 nm) and the optical diffraction limit (>400 nm). The last decade has seen the emergence of super-resolution imaging methods that effectively break the optical diffraction barrier to yield truly nanoscale information in intact biological samples. This study reports the first visualizations of TLR4 distributions on intact cells at image resolutions of <30 nm using a novel, dual-color stochastic optical reconstruction microscopy (STORM) technique. This methodology permits distinction between receptors containing bound LPS from those without at the nanoscale. Importantly, we also show that LPS derived from immuno-stimulatory bacteria resulted in significantly higher LPS-TLR4 cluster sizes and a nearly two-fold greater ligand/receptor colocalization as compared to immuno-evading LPS. PMID:22807232

5 CFR 317.605 - Tenure of appointees.

Code of Federal Regulations, 2010 CFR

2010-01-01

... not been terminated earlier. (d) An employee: (1) Who received a limited appointment without a break... Executive Service, and (2) Whose limited appointment is terminated for reasons other than misconduct...

Structure of the European upper mantle revealed by adjoint tomography

NASA Astrophysics Data System (ADS)

Zhu, Hejun; Bozdağ, Ebru; Peter, Daniel; Tromp, Jeroen

2012-07-01

Images of the European crust and upper mantle, created using seismic tomography, identify the Cenozoic Rift System and related volcanism in central and western Europe. They also reveal subduction and slab roll back in the Mediterranean-Carpathian region. However, existing tomographic models are either high in resolution, but cover only a limited area, or low in resolution, and thus miss the finer-scale details of mantle structure. Here we simultaneously fit frequency-dependent phase anomalies of body and surface waveforms in complete three-component seismograms with an iterative inversion strategy involving adjoint methods, to create a tomographic model of the European upper mantle. We find that many of the smaller-scale structures such as slabs, upwellings and delaminations that emerge naturally in our model are consistent with existing images. However, we also derive some hitherto unidentified structures. Specifically, we interpret fast seismic-wave speeds beneath the Dinarides Mountains, southern Europe, as a signature of northeastward subduction of the Adria plate; slow seismic-wave speeds beneath the northern part of the Rhine Graben as a reservoir connected to the Eifel hotspot; and fast wave-speed anomalies beneath Scandinavia as a lithospheric drip, where the lithosphere is delaminating and breaking away. Our model sheds new light on the enigmatic palaeotectonic history of Europe.

Numerical experiment for ultrasonic-measurement-integrated simulation of three-dimensional unsteady blood flow.

PubMed

Funamoto, Kenichi; Hayase, Toshiyuki; Saijo, Yoshifumi; Yambe, Tomoyuki

2008-08-01

Integration of ultrasonic measurement and numerical simulation is a possible way to break through limitations of existing methods for obtaining complete information on hemodynamics. We herein propose Ultrasonic-Measurement-Integrated (UMI) simulation, in which feedback signals based on the optimal estimation of errors in the velocity vector determined by measured and computed Doppler velocities at feedback points are added to the governing equations. With an eye towards practical implementation of UMI simulation with real measurement data, its efficiency for three-dimensional unsteady blood flow analysis and a method for treating low time resolution of ultrasonic measurement were investigated by a numerical experiment dealing with complicated blood flow in an aneurysm. Even when simplified boundary conditions were applied, the UMI simulation reduced the errors of velocity and pressure to 31% and 53% in the feedback domain which covered the aneurysm, respectively. Local maximum wall shear stress was estimated, showing both the proper position and the value with 1% deviance. A properly designed intermittent feedback applied only at the time when measurement data were obtained had the same computational accuracy as feedback applied at every computational time step. Hence, this feedback method is a possible solution to overcome the insufficient time resolution of ultrasonic measurement.

Genome-Wide Profiling of DNA Double-Strand Breaks by the BLESS and BLISS Methods.

PubMed

Mirzazadeh, Reza; Kallas, Tomasz; Bienko, Magda; Crosetto, Nicola

2018-01-01

DNA double-strand breaks (DSBs) are major DNA lesions that are constantly formed during physiological processes such as DNA replication, transcription, and recombination, or as a result of exogenous agents such as ionizing radiation, radiomimetic drugs, and genome editing nucleases. Unrepaired DSBs threaten genomic stability by leading to the formation of potentially oncogenic rearrangements such as translocations. In past few years, several methods based on next-generation sequencing (NGS) have been developed to study the genome-wide distribution of DSBs or their conversion to translocation events. We developed Breaks Labeling, Enrichment on Streptavidin, and Sequencing (BLESS), which was the first method for direct labeling of DSBs in situ followed by their genome-wide mapping at nucleotide resolution (Crosetto et al., Nat Methods 10:361-365, 2013). Recently, we have further expanded the quantitative nature, applicability, and scalability of BLESS by developing Breaks Labeling In Situ and Sequencing (BLISS) (Yan et al., Nat Commun 8:15058, 2017). Here, we first present an overview of existing methods for genome-wide localization of DSBs, and then focus on the BLESS and BLISS methods, discussing different assay design options depending on the sample type and application.

PolySUMOylation by Siz2 and Mms21 triggers relocation of DNA breaks to nuclear pores through the Slx5/Slx8 STUbL

PubMed Central

Horigome, Chihiro; Bustard, Denise E.; Marcomini, Isabella; Delgoshaie, Neda; Tsai-Pflugfelder, Monika; Cobb, Jennifer A.; Gasser, Susan M.

2016-01-01

High-resolution imaging shows that persistent DNA damage in budding yeast localizes in distinct perinuclear foci for repair. The signals that trigger DNA double-strand break (DSB) relocation or determine their destination are unknown. We show here that DSB relocation to the nuclear envelope depends on SUMOylation mediated by the E3 ligases Siz2 and Mms21. In G1, a polySUMOylation signal deposited coordinately by Mms21 and Siz2 recruits the SUMO targeted ubiquitin ligase Slx5/Slx8 to persistent breaks. Both Slx5 and Slx8 are necessary for damage relocation to nuclear pores. When targeted to an undamaged locus, however, Slx5 alone can mediate relocation in G1-phase cells, bypassing the requirement for polySUMOylation. In contrast, in S-phase cells, monoSUMOylation mediated by the Rtt107-stabilized SMC5/6–Mms21 E3 complex drives DSBs to the SUN domain protein Mps3 in a manner independent of Slx5. Slx5/Slx8 and binding to pores favor repair by ectopic break-induced replication and imprecise end-joining. PMID:27056668

Modeling the safety impacts of driving hours and rest breaks on truck drivers considering time-dependent covariates.

PubMed

Chen, Chen; Xie, Yuanchang

2014-12-01

Driving hours and rest breaks are closely related to driver fatigue, which is a major contributor to truck crashes. This study investigates the effects of driving hours and rest breaks on commercial truck driver safety. A discrete-time logistic regression model is used to evaluate the crash odds ratios of driving hours and rest breaks. Driving time is divided into 11 one hour intervals. These intervals and rest breaks are modeled as dummy variables. In addition, a Cox proportional hazards regression model with time-dependent covariates is used to assess the transient effects of rest breaks, which consists of a fixed effect and a variable effect. Data collected from two national truckload carriers in 2009 and 2010 are used. The discrete-time logistic regression result indicates that only the crash odds ratio of the 11th driving hour is statistically significant. Taking one, two, and three rest breaks can reduce drivers' crash odds by 68%, 83%, and 85%, respectively, compared to drivers who did not take any rest breaks. The Cox regression result shows clear transient effects for rest breaks. It also suggests that drivers may need some time to adjust themselves to normal driving tasks after a rest break. Overall, the third rest break's safety benefit is very limited based on the results of both models. The findings of this research can help policy makers better understand the impact of driving time and rest breaks and develop more effective rules to improve commercial truck safety. Copyright © 2014 National Safety Council and Elsevier Ltd. All rights reserved.

Array painting reveals a high frequency of balanced translocations in breast cancer cell lines that break in cancer-relevant genes

PubMed Central

Howarth, KD; Blood, KA; Ng, BL; Beavis, JC; Chua, Y; Cooke, SL; Raby, S; Ichimura, K; Collins, VP; Carter, NP; Edwards, PAW

2008-01-01

Chromosome translocations in the common epithelial cancers are abundant, yet little is known about them. They have been thought to be almost all unbalanced and therefore dismissed as mostly mediating tumour suppressor loss. We present a comprehensive analysis by array painting of the chromosome translocations of breast cancer cell lines HCC1806, HCC1187 and ZR-75-30. In array painting, chromosomes are isolated by flow cytometry, amplified and hybridized to DNA microarrays. A total of 200 breakpoints were identified and all were mapped to 1Mb resolution on BAC arrays, then 40 selected breakpoints, including all balanced breakpoints, were further mapped on tiling-path BAC arrays or to around 2kb resolution using oligonucleotide arrays. Many more of the translocations were balanced at 1Mb resolution than expected, either reciprocal (eight in total) or balanced for at least one participating chromosome (19 paired breakpoints). Secondly, many of the breakpoints were at genes that are plausible targets of oncogenic translocation, including balanced breaks at CTCF, EP300/p300, and FOXP4. Two gene fusions were demonstrated, TAX1BP1-AHCY and RIF1-PKD1L1. Our results support the idea that chromosome rearrangements may play an important role in common epithelial cancers such as breast cancer. PMID:18084325

Supersymmetry breaking and Nambu-Goldstone fermions with cubic dispersion

NASA Astrophysics Data System (ADS)

Sannomiya, Noriaki; Katsura, Hosho; Nakayama, Yu

2017-03-01

We introduce a lattice fermion model in one spatial dimension with supersymmetry (SUSY) but without particle number conservation. The Hamiltonian is defined as the anticommutator of two nilpotent supercharges Q and Q†. Each supercharge is built solely from spinless fermion operators and depends on a parameter g . The system is strongly interacting for small g , and in the extreme limit g =0 , the number of zero-energy ground states grows exponentially with the system size. By contrast, in the large-g limit, the system is noninteracting and SUSY is broken spontaneously. We study the model for modest values of g and show that under certain conditions spontaneous SUSY breaking occurs in both finite and infinite chains. We analyze the low-energy excitations both analytically and numerically. Our analysis suggests that the Nambu-Goldstone fermions accompanying the spontaneous SUSY breaking have cubic dispersion at low energies.

Goldstone mode and pair-breaking excitations in atomic Fermi superfluids

NASA Astrophysics Data System (ADS)

Hoinka, Sascha; Dyke, Paul; Lingham, Marcus G.; Kinnunen, Jami J.; Bruun, Georg M.; Vale, Chris J.

2017-10-01

Spontaneous symmetry breaking is a central paradigm of elementary particle physics, magnetism, superfluidity and superconductivity. According to Goldstone's theorem, phase transitions that break continuous symmetries lead to the existence of gapless excitations in the long-wavelength limit. These Goldstone modes can become the dominant low-energy excitation, showing that symmetry breaking has a profound impact on the physical properties of matter. Here, we present a comprehensive study of the elementary excitations in a homogeneous strongly interacting Fermi gas through the crossover from a Bardeen-Cooper-Schrieffer (BCS) superfluid to a Bose-Einstein condensate (BEC) of molecules using two-photon Bragg spectroscopy. The spectra exhibit a discrete Goldstone mode, associated with the broken-symmetry superfluid phase, as well as pair-breaking single-particle excitations. Our techniques yield a direct determination of the superfluid pairing gap and speed of sound in close agreement with strong-coupling theories.

Achieving atomic resolution magnetic dichroism by controlling the phase symmetry of an electron probe

DOE PAGES

Rusz, Jan; Idrobo, Juan -Carlos; Bhowmick, Somnath

2014-09-30

The calculations presented here reveal that an electron probe carrying orbital angular momentum is just a particular case of a wider class of electron beams that can be used to measure electron magnetic circular dichroism (EMCD) with atomic resolution. It is possible to obtain an EMCD signal with atomic resolution by simply breaking the symmetry of the electron probe phase front using the aberration-corrected optics of a scanning transmission electron microscope. The probe’s required phase distribution depends on the sample’s magnetic symmetry and crystal structure. The calculations indicate that EMCD signals that use the electron probe’s phase are as strongmore » as those obtained by nanodiffraction methods.« less

NEWTON - NEW portable multi-sensor scienTific instrument for non-invasive ON-site characterization of rock from planetary surface and sub-surfaces

NASA Astrophysics Data System (ADS)

Díaz-Michelena, M.; de Frutos, J.; Ordóñez, A. A.; Rivero, M. A.; Mesa, J. L.; González, L.; Lavín, C.; Aroca, C.; Sanz, M.; Maicas, M.; Prieto, J. L.; Cobos, P.; Pérez, M.; Kilian, R.; Baeza, O.; Langlais, B.; Thébault, E.; Grösser, J.; Pappusch, M.

2017-09-01

In space instrumentation, there is currently no instrument dedicated to susceptibly or complete magnetization measurements of rocks. Magnetic field instrument suites are generally vector (or scalar) magnetometers, which locally measure the magnetic field. When mounted on board rovers, the electromagnetic perturbations associated with motors and other elements make it difficult to reap the benefits from the inclusion of such instruments. However, magnetic characterization is essential to understand key aspects of the present and past history of planetary objects. The work presented here overcomes the limitations currently existing in space instrumentation by developing a new portable and compact multi-sensor instrument for ground breaking high-resolution magnetic characterization of planetary surfaces and sub-surfaces. This new technology introduces for the first time magnetic susceptometry (real and imaginary parts) as a complement to existing compact vector magnetometers for planetary exploration. This work aims to solve the limitations currently existing in space instrumentation by means of providing a new portable and compact multi-sensor instrument for use in space, science and planetary exploration to solve some of the open questions on the crustal and more generally planetary evolution within the Solar System.

Safety of working patterns among UK neuroradiologists: what can we learn from the aviation industry and cognitive science?

PubMed

Reicher, John; Currie, Stuart; Birchall, Daniel

2018-04-01

As the volume and complexity of imaging in the UK continues to rise, there is pressure on radiologists to spend increasing lengths of time reporting to cope with the growing workload. However, there is limited guidance for radiologists about structuring the working day to strike the necessary balance between achieving satisfactory reporting volume and maintaining quality and safety. We surveyed 86 neuroradiologists (receiving 59 responses), regarding time spent reporting, frequency and duration of work breaks, and break activities. Our results demonstrate that some neuroradiologists report for up to 12 h a day and for 4 h before taking a break. Mean duration of breaks is less than 15 min and these often consist of computer screen-based or cognitively demanding tasks. Many areas of medicine have looked to the aviation industry to develop improvements in safety through regulated, standardised practices. There are parallels between the work of air traffic controllers (ATCs) and radiologists. We review the legislation that controls the working hours of UK ATCs to minimise fatigue-related errors, and its scientific basis. We also consider the vigilance decrement, a concept in cognitive science which describes the reduction in performance with increasing time-on-task. We conclude that, in comparison with ATCs, work patterns among radiologists are poorly standardised and potentially dangerous. Evidence suggests that placing limits on reporting time and minimum break duration, as well as ensuring appropriate break activities, can benefit reporting quality. It is imperative that radiologists and managers heed these lessons, to improve standards and protect patients from error.

Direct microscopic image and measurement of the atomization process of a port fuel injector

NASA Astrophysics Data System (ADS)

Esmail, Mohamed; Kawahara, Nobuyuki; Tomita, Eiji; Sumida, Mamoru

2010-07-01

The main objective of this study is to observe and investigate the phenomena of atomization, i.e. the fuel break-up process very close to the nozzle exit of a practical port fuel injector (PFI). In order to achieve this objective, direct microscopic images of the atomization process were obtained using an ultra-high-speed video camera that could record 102 frames at rates of up to 1 Mfps, coupled with a long-distance microscope and Barlow lens. The experiments were carried out using a PFI in a closed chamber at atmospheric pressure. Time-series images of the spray behaviour were obtained with a high temporal resolution using backlighting. The direct microscopic images of a liquid column break-up were compared with experimental results from laser-induced exciplex fluorescence (LIEF), and the wavelength obtained from the experimental results compared with that predicated from the Kelvin-Helmholtz break-up model. The droplet size diameters from a ligament break-up were compared with results predicated from Weber's analysis. Furthermore, experimental results of the mean droplet diameter from a direct microscopic image were compared with the results obtained from phase Doppler anemometry (PDA) experimental results. Three conclusions were obtained from this study. The atomization processes and detailed characterizations of the break-up of a liquid column were identified; the direct microscopic image results were in good agreement with the results obtained from LIEF, experimental results of the wavelength were in good agreement with those from the Kelvin-Helmholtz break-up model. The break-up process of liquid ligaments into droplets was investigated, and Weber's analysis of the predicated droplet diameter from ligament break-up was found to be applicable only at larger wavelengths. Finally, the direct microscopic image method and PDA method give qualitatively similar trends for droplet size distribution and quantitatively similar values of Sauter mean diameter.

Near-Bed Turbulent Kinetic Energy Budget Under a Large-Scale Plunging Breaking Wave Over a Fixed Bar

NASA Astrophysics Data System (ADS)

van der Zanden, Joep; van der A, Dominic A.; Cáceres, Iván.; Hurther, David; McLelland, Stuart J.; Ribberink, Jan S.; O'Donoghue, Tom

2018-02-01

Hydrodynamics under regular plunging breaking waves over a fixed breaker bar were studied in a large-scale wave flume. A previous paper reported on the outer flow hydrodynamics; the present paper focuses on the turbulence dynamics near the bed (up to 0.10 m from the bed). Velocities were measured with high spatial and temporal resolution using a two component laser Doppler anemometer. The results show that even at close distance from the bed (1 mm), the turbulent kinetic energy (TKE) increases by a factor five between the shoaling, and breaking regions because of invasion of wave breaking turbulence. The sign and phase behavior of the time-dependent Reynolds shear stresses at elevations up to approximately 0.02 m from the bed (roughly twice the elevation of the boundary layer overshoot) are mainly controlled by local bed-shear-generated turbulence, but at higher elevations Reynolds stresses are controlled by wave breaking turbulence. The measurements are subsequently analyzed to investigate the TKE budget at wave-averaged and intrawave time scales. Horizontal and vertical turbulence advection, production, and dissipation are the major terms. A two-dimensional wave-averaged circulation drives advection of wave breaking turbulence through the near-bed layer, resulting in a net downward influx in the bar trough region, followed by seaward advection along the bar's shoreward slope, and an upward outflux above the bar crest. The strongly nonuniform flow across the bar combined with the presence of anisotropic turbulence enhances turbulent production rates near the bed.

Estimating the resolution limit of the map equation in community detection

NASA Astrophysics Data System (ADS)

Kawamoto, Tatsuro; Rosvall, Martin

2015-01-01

A community detection algorithm is considered to have a resolution limit if the scale of the smallest modules that can be resolved depends on the size of the analyzed subnetwork. The resolution limit is known to prevent some community detection algorithms from accurately identifying the modular structure of a network. In fact, any global objective function for measuring the quality of a two-level assignment of nodes into modules must have some sort of resolution limit or an external resolution parameter. However, it is yet unknown how the resolution limit affects the so-called map equation, which is known to be an efficient objective function for community detection. We derive an analytical estimate and conclude that the resolution limit of the map equation is set by the total number of links between modules instead of the total number of links in the full network as for modularity. This mechanism makes the resolution limit much less restrictive for the map equation than for modularity; in practice, it is orders of magnitudes smaller. Furthermore, we argue that the effect of the resolution limit often results from shoehorning multilevel modular structures into two-level descriptions. As we show, the hierarchical map equation effectively eliminates the resolution limit for networks with nested multilevel modular structures.

Contribution of Anthropogenic Warming to California Drought During 2012-2014

NASA Technical Reports Server (NTRS)

Williams, A. Park; Seager, Richard; Abatzoglou, John T.; Cook, Benjamin I.; Smerdon, Jason E.; Cook, Edward R.

2015-01-01

A suite of climate data sets and multiple representations of atmospheric moisture demand are used to calculate many estimates of the self-calibrated Palmer Drought Severity Index, a proxy for near-surface soil moisture, across California from 1901 to 2014 at high spatial resolution. Based on the ensemble of calculations, California drought conditions were record breaking in 2014, but probably not record breaking in 2012-2014, contrary to prior findings. Regionally, the 2012-2014 drought was record breaking in the agriculturally important southern Central Valley and highly populated coastal areas. Contributions of individual climate variables to recent drought are also examined, including the temperature component associated with anthropogenic warming. Precipitation is the primary driver of drought variability but anthropogenic warming is estimated to have accounted for 8-27 percent of the observed drought anomaly in 2012-2014 and 5-18 percent in 2014. Although natural variability dominates, anthropogenic warming has substantially increased the overall likelihood of extreme California droughts.

Constitutional chromothripsis rearrangements involve clustered double-stranded DNA breaks and nonhomologous repair mechanisms.

PubMed

Kloosterman, Wigard P; Tavakoli-Yaraki, Masoumeh; van Roosmalen, Markus J; van Binsbergen, Ellen; Renkens, Ivo; Duran, Karen; Ballarati, Lucia; Vergult, Sarah; Giardino, Daniela; Hansson, Kerstin; Ruivenkamp, Claudia A L; Jager, Myrthe; van Haeringen, Arie; Ippel, Elly F; Haaf, Thomas; Passarge, Eberhard; Hochstenbach, Ron; Menten, Björn; Larizza, Lidia; Guryev, Victor; Poot, Martin; Cuppen, Edwin

2012-06-28

Chromothripsis represents a novel phenomenon in the structural variation landscape of cancer genomes. Here, we analyze the genomes of ten patients with congenital disease who were preselected to carry complex chromosomal rearrangements with more than two breakpoints. The rearrangements displayed unanticipated complexity resembling chromothripsis. We find that eight of them contain hallmarks of multiple clustered double-stranded DNA breaks (DSBs) on one or more chromosomes. In addition, nucleotide resolution analysis of 98 breakpoint junctions indicates that break repair involves nonhomologous or microhomology-mediated end joining. We observed that these eight rearrangements are balanced or contain sporadic deletions ranging in size between a few hundred base pairs and several megabases. The two remaining complex rearrangements did not display signs of DSBs and contain duplications, indicative of rearrangement processes involving template switching. Our work provides detailed insight into the characteristics of chromothripsis and supports a role for clustered DSBs driving some constitutional chromothripsis rearrangements. Copyright © 2012 The Authors. Published by Elsevier Inc. All rights reserved.

Symmetry breaking in tensor models

NASA Astrophysics Data System (ADS)

Benedetti, Dario; Gurau, Razvan

2015-11-01

In this paper we analyze a quartic tensor model with one interaction for a tensor of arbitrary rank. This model has a critical point where a continuous limit of infinitely refined random geometries is reached. We show that the critical point corresponds to a phase transition in the tensor model associated to a breaking of the unitary symmetry. We analyze the model in the two phases and prove that, in a double scaling limit, the symmetric phase corresponds to a theory of infinitely refined random surfaces, while the broken phase corresponds to a theory of infinitely refined random nodal surfaces. At leading order in the double scaling limit planar surfaces dominate in the symmetric phase, and planar nodal surfaces dominate in the broken phase.

Breaking Ground: Carving New Forms for Resolving Conflict. Project Seed.

ERIC Educational Resources Information Center

Brennan, Judith; Lynch, Stephen

One of eight papers from Project Seed, this paper describes a conflict resolution program co-facilitated by a special educator and a guidance counselor and designed to help young students who have conflicts with authority figures in school and elsewhere, as well as those students with low self-esteem and poor social skills. The project described…

Estimate of neutrons event-by-event in DREAM

NASA Astrophysics Data System (ADS)

Hauptman, John; DREAM Collaboration

2009-04-01

We have measured the contribution of neutrons to hadronic showers in the DREAM module event-by-event as a means to estimate the event-by-event fluctuations in binding energy losses by hadrons as they break up nuclei of the Cu absorber. We make a preliminary assessment of the consequences for hadronic energy resolution in dual-readout calorimeters.

Controlled breaks as a fatigue countermeasure on the flight deck

NASA Technical Reports Server (NTRS)

Neri, David F.; Oyung, Raymond L.; Colletti, Laura M.; Mallis, Melissa M.; Tam, Patricia Y.; Dinges, David F.

2002-01-01

BACKGROUND: A major challenge for flight crews is the need to maintain vigilance during long, highly automated nighttime flights. No system currently exists to assist in managing alertness, and countermeasure options are limited. Surveys reveal many pilots use breaks as an in-flight countermeasure, but there have been no controlled studies of their effectiveness. HYPOTHESIS: We hypothesized that brief, regular breaks could improve alertness and performance during an overnight flight. METHOD: A 6-h, uneventful, nighttime flight in a Boeing 747-400 flight simulator was flown by fourteen two-man crews. The 14 subjects in the treatment group received 5 short breaks spaced hourly during cruise; the 14 subjects in the control group received 1 break in the middle of cruise. Continuous EEG/EOG, subjective sleepiness, and psychomotor vigilance performance data were collected. RESULTS: During the latter part of the night, the treatment group showed significant reductions for 15 min post-break in slow eye movements, theta-band activity, and unintended sleep episodes compared with the control group. The treatment group reported significantly greater subjective alertness for up to 25 min post-break, with strongest effects near the time of the circadian trough. There was no evidence of objective vigilance performance improvement at 15-25 min post-break, with expected performance deterioration occurring due to elevated sleep drive and circadian time. CONCLUSIONS: The physiological and subjective data indicate the breaks reduced nighttime sleepiness for at least 15 min post-break and may have masked sleepiness for up to 25 min, suggesting the potential usefulness of short-duration breaks as an in-flight fatigue countermeasure.

Controlled breaks as a fatigue countermeasure on the flight deck.

PubMed

Neri, David F; Oyung, Raymond L; Colletti, Laura M; Mallis, Melissa M; Tam, Patricia Y; Dinges, David F

2002-07-01

A major challenge for flight crews is the need to maintain vigilance during long, highly automated nighttime flights. No system currently exists to assist in managing alertness, and countermeasure options are limited. Surveys reveal many pilots use breaks as an in-flight countermeasure, but there have been no controlled studies of their effectiveness. We hypothesized that brief, regular breaks could improve alertness and performance during an overnight flight. A 6-h, uneventful, nighttime flight in a Boeing 747-400 flight simulator was flown by fourteen two-man crews. The 14 subjects in the treatment group received 5 short breaks spaced hourly during cruise; the 14 subjects in the control group received 1 break in the middle of cruise. Continuous EEG/EOG, subjective sleepiness, and psychomotor vigilance performance data were collected. During the latter part of the night, the treatment group showed significant reductions for 15 min post-break in slow eye movements, theta-band activity, and unintended sleep episodes compared with the control group. The treatment group reported significantly greater subjective alertness for up to 25 min post-break, with strongest effects near the time of the circadian trough. There was no evidence of objective vigilance performance improvement at 15-25 min post-break, with expected performance deterioration occurring due to elevated sleep drive and circadian time. The physiological and subjective data indicate the breaks reduced nighttime sleepiness for at least 15 min post-break and may have masked sleepiness for up to 25 min, suggesting the potential usefulness of short-duration breaks as an in-flight fatigue countermeasure.

Probabilistic pipe fracture evaluations for leak-rate-detection applications

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

Rahman, S.; Ghadiali, N.; Paul, D.

1995-04-01

Regulatory Guide 1.45, {open_quotes}Reactor Coolant Pressure Boundary Leakage Detection Systems,{close_quotes} was published by the U.S. Nuclear Regulatory Commission (NRC) in May 1973, and provides guidance on leak detection methods and system requirements for Light Water Reactors. Additionally, leak detection limits are specified in plant Technical Specifications and are different for Boiling Water Reactors (BWRs) and Pressurized Water Reactors (PWRs). These leak detection limits are also used in leak-before-break evaluations performed in accordance with Draft Standard Review Plan, Section 3.6.3, {open_quotes}Leak Before Break Evaluation Procedures{close_quotes} where a margin of 10 on the leak detection limit is used in determining the crackmore » size considered in subsequent fracture analyses. This study was requested by the NRC to: (1) evaluate the conditional failure probability for BWR and PWR piping for pipes that were leaking at the allowable leak detection limit, and (2) evaluate the margin of 10 to determine if it was unnecessarily large. A probabilistic approach was undertaken to conduct fracture evaluations of circumferentially cracked pipes for leak-rate-detection applications. Sixteen nuclear piping systems in BWR and PWR plants were analyzed to evaluate conditional failure probability and effects of crack-morphology variability on the current margins used in leak rate detection for leak-before-break.« less

The (Untold) Drama of the Turning Page: The Role of Page Breaks in Understanding Picture Books

ERIC Educational Resources Information Center

Jacobs, Katrina Emily Bartow

2016-01-01

While scholars have recognized the importance of page breaks in both the construction and comprehension of narrative within picture books, there has previously been limited research that focused directly on how children discuss and make sense of these spaces in the text. Yet, because of their nature as dramatic gaps in the narrative, page breaks…

Interpreting Chromosome Aberration Spectra

NASA Technical Reports Server (NTRS)

Levy, Dan; Reeder, Christopher; Loucas, Bradford; Hlatky, Lynn; Chen, Allen; Cornforth, Michael; Sachs, Rainer

2007-01-01

Ionizing radiation can damage cells by breaking both strands of DNA in multiple locations, essentially cutting chromosomes into pieces. The cell has enzymatic mechanisms to repair such breaks; however, these mechanisms are imperfect and, in an exchange process, may produce a large-scale rearrangement of the genome, called a chromosome aberration. Chromosome aberrations are important in killing cells, during carcinogenesis, in characterizing repair/misrepair pathways, in retrospective radiation biodosimetry, and in a number of other ways. DNA staining techniques such as mFISH ( multicolor fluorescent in situ hybridization) provide a means for analyzing aberration spectra by examining observed final patterns. Unfortunately, an mFISH observed final pattern often does not uniquely determine the underlying exchange process. Further, resolution limitations in the painting protocol sometimes lead to apparently incomplete final patterns. We here describe an algorithm for systematically finding exchange processes consistent with any observed final pattern. This algorithm uses aberration multigraphs, a mathematical formalism that links the various aspects of aberration formation. By applying a measure to the space of consistent multigraphs, we will show how to generate model-specific distributions of aberration processes from mFISH experimental data. The approach is implemented by software freely available over the internet. As a sample application, we apply these algorithms to an aberration data set, obtaining a distribution of exchange cycle sizes, which serves to measure aberration complexity. Estimating complexity, in turn, helps indicate how damaging the aberrations are and may facilitate identification of radiation type in retrospective biodosimetry.

Jobs: women's double burden.

PubMed

1995-01-01

Whereas international conventions and national laws provide equal opportunities for women in employment, the reality of women's lives keeps a disproportionate number of women unemployed, underemployed, and living in poverty. The UN itself, which officially is working toward equity among its employees, has a staff composed of just 32.6% women, and women comprise only 10.5% of the top end of the hierarchy. In areas where women's labor force participation has increased dramatically, women typically earn 30-40% less than men doing the same job or else their employment is limited to "traditional female" service positions. The fact that women and girls have received an inadequate education makes it extremely difficult to break the barriers of discrimination in developing countries. The empowerment of women will break the education barrier, and, when that falls, many other barriers will follow suit. Efforts are already underway to break structural barriers caused by economic and social policies. For example, a more flexible pattern of work has been proposed which will include the voluntary assumption of flexible hours, job-sharing, and part-time work. The concept of work is also being broadened to include the important human services that women traditionally provide on a volunteer basis. This will lead to a valuation of women's contribution to society which can be added to calculations of gross domestic product. Women also need protection as they attempt to eke out a living in the informal sector which has been the traditional avenue for women to earn money. This sector is not protected by law and is subject to extortion by officials and by male competitors. A variety of measures is under consideration to increase the protection of informal sector workers. Women also need protection in the conventional work place, especially as they enter fields traditionally reserved for men. These questions are important even in the context of global unemployment because these issues must be addressed or their resolution to women's disadvantage will gain the mantle of tradition.

Nuclear ARP2/3 drives DNA break clustering for homology-directed repair.

PubMed

Schrank, Benjamin R; Aparicio, Tomas; Li, Yinyin; Chang, Wakam; Chait, Brian T; Gundersen, Gregg G; Gottesman, Max E; Gautier, Jean

2018-06-20

DNA double-strand breaks repaired by non-homologous end joining display limited DNA end-processing and chromosomal mobility. By contrast, double-strand breaks undergoing homology-directed repair exhibit extensive processing and enhanced motion. The molecular basis of this movement is unknown. Here, using Xenopus laevis cell-free extracts and mammalian cells, we establish that nuclear actin, WASP, and the actin-nucleating ARP2/3 complex are recruited to damaged chromatin undergoing homology-directed repair. We demonstrate that nuclear actin polymerization is required for the migration of a subset of double-strand breaks into discrete sub-nuclear clusters. Actin-driven movements specifically affect double-strand breaks repaired by homology-directed repair in G2 cell cycle phase; inhibition of actin nucleation impairs DNA end-processing and homology-directed repair. By contrast, ARP2/3 is not enriched at double-strand breaks repaired by non-homologous end joining and does not regulate non-homologous end joining. Our findings establish that nuclear actin-based mobility shapes chromatin organization by generating repair domains that are essential for homology-directed repair in eukaryotic cells.

PT-symmetry breaking with divergent potentials: Lattice and continuum cases

NASA Astrophysics Data System (ADS)

Joglekar, Yogesh N.; Scott, Derek D.; Saxena, Avadh

2014-09-01

We investigate the parity- and time-reversal (PT-) symmetry breaking in lattice models in the presence of long-ranged, non-Hermitian, PT-symmetric potentials that remain finite or become divergent in the continuum limit. By scaling analysis of the fragile PT threshold for an open finite lattice, we show that continuum loss-gain potentials Vα(x)∝i|x|αsgn(x) have a positive PT-breaking threshold for α >-2, and a zero threshold for α ≤-2. When α <0 localized states with complex (conjugate) energies in the continuum energy band occur at higher loss-gain strengths. We investigate the signatures of PT-symmetry breaking in coupled waveguides, and show that the emergence of localized states dramatically shortens the relevant time scale in the PT-symmetry broken region.

The role of the non-homologous end-joining pathway in lymphocyte development.

PubMed

Rooney, Sean; Chaudhuri, Jayanta; Alt, Frederick W

2004-08-01

One of the most toxic insults a cell can incur is a disruption of its linear DNA in the form of a double-strand break (DSB). Left unrepaired, or repaired improperly, these lesions can result in cell death or neoplastic transformation. Despite these dangers, lymphoid cells purposely introduce DSBs into their genome to maximize the diversity and effector functions of their antigen receptor genes. While the generation of breaks requires distinct lymphoid-specific factors, their resolution requires various ubiquitously expressed DNA-repair proteins, known collectively as the non-homologous end-joining pathway. In this review, we discuss the factors that constitute this pathway as well as the evidence of their involvement in two lymphoid-specific DNA recombination events.

Kilometric Scale Modeling of the North West European Shelf Seas: Exploring the Spatial and Temporal Variability of Internal Tides

NASA Astrophysics Data System (ADS)

Guihou, K.; Polton, J.; Harle, J.; Wakelin, S.; O'Dea, E.; Holt, J.

2018-01-01

The North West European Shelf break acts as a barrier to the transport and exchange between the open ocean and the shelf seas. The strong spatial variability of these exchange processes is hard to fully explore using observations, and simulations generally are too coarse to simulate the fine-scale processes over the whole region. In this context, under the FASTNEt program, a new NEMO configuration of the North West European Shelf and Atlantic Margin at 1/60° (˜1.8 km) has been developed, with the objective to better understand and quantify the seasonal and interannual variability of shelf break processes. The capability of this configuration to reproduce the seasonal cycle in SST, the barotropic tide, and fine-resolution temperature profiles is assessed against a basin-scale (1/12°, ˜9 km) configuration and a standard regional configuration (7 km resolution). The seasonal cycle is well reproduced in all configurations though the fine-resolution allows the simulation of smaller scale processes. Time series of temperature at various locations on the shelf show the presence of internal waves with a strong spatiotemporal variability. Spectral analysis of the internal waves reveals peaks at the diurnal, semidiurnal, inertial, and quarter-diurnal bands, which are only realistically reproduced in the new configuration. Tidally induced pycnocline variability is diagnosed in the model and shown to vary with the spring neap cycle with mean displacement amplitudes in excess of 2 m for 30% of the stratified domain. With sufficiently fine resolution, internal tides are shown to be generated at numerous bathymetric features resulting in a complex pycnocline displacement superposition pattern.

Breaking the limits of structural and mechanical imaging of the heterogeneous structure of coal macerals

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

Collins, L.; Tselev, A.; Jesse, S.

The correlation between local mechanical (elasto-plastic) and structural (composition) properties of coal presents significant fundamental and practical interest for coal processing and the development of rheological models of coal to coke transformations and for advancing novel approaches. Here, we explore the relationship between the local structural, chemical composition and mechanical properties of coal using a combination of confocal micro-Raman imaging and band excitation atomic force acoustic microscopy (BE-AFAM) for a bituminous coal. This allows high resolution imaging (10s of nm) of mechanical properties of the heterogeneous (banded) architecture of coal and correlating them to the optical gap, average crystallite size,more » the bond-bending disorder of sp2 aromatic double bonds and the defect density. This methodology hence allows the structural and mechanical properties of coal components (lithotypes, microlithotypes, and macerals) to be understood, and related to local chemical structure, potentially allowing for knowledge-based modelling and optimization of coal utilization processes.« less

The first close-up images of Jupiter's polar regions: Results from the Juno mission JunoCam instrument

NASA Astrophysics Data System (ADS)

Orton, Glenn S.; Hansen, Candice; Caplinger, Michael; Ravine, Michael; Atreya, Sushil; Ingersoll, Andrew P.; Jensen, Elsa; Momary, Thomas; Lipkaman, Leslie; Krysak, Daniel; Zimdar, Robert; Bolton, Scott

2017-05-01

During Juno's first perijove encounter, the JunoCam instrument acquired the first images of Jupiter's polar regions at 50-70 km spatial scale at low emission angles. Poleward of 64-68° planetocentric latitude, where Jupiter's east-west banded structure breaks down, several types of discrete features appear on a darker background. Cyclonic oval features are clustered near both poles. Other oval-shaped features are also present, ranging in size from 2000 km down to JunoCam's resolution limits. The largest and brightest features often have chaotic shapes. Two narrow linear features in the north, associated with an overlying haze feature, traverse tens of degrees of longitude. JunoCam also detected an optically thin cloud or haze layer past the northern nightside terminator estimated to be 58 ± 21 km (approximately three scale heights) above the main cloud deck. JunoCam will acquire polar images on every perijove, allowing us to track the state and evolution of longer-lived features.

Constraining the Optical Emission from the Double Pulsar System J0737-3039

NASA Astrophysics Data System (ADS)

Ferraro, F. R.; Mignani, R. P.; Pallanca, C.; Dalessandro, E.; Lanzoni, B.; Pellizzoni, A.; Possenti, A.; Burgay, M.; Camilo, F.; D'Amico, N.; Lyne, A. G.; Kramer, M.; Manchester, R. N.

2012-04-01

We present the first optical observations of the unique system J0737-3039 (composed of two pulsars, hereafter PSR-A and PSR-B). Ultra-deep optical observations, performed with the High Resolution Camera of the Advanced Camera for Surveys on board the Hubble Space Telescope, could not detect any optical emission from the system down to m F435W = 27.0 and m F606W = 28.3. The estimated optical flux limits are used to constrain the three-component (two thermal and one non-thermal) model recently proposed to reproduce the XMM-Newton X-ray spectrum. They suggest the presence of a break at low energies in the non-thermal power-law component of PSR-A and are compatible with the expected blackbody emission from the PSR-B surface. The corresponding efficiency of the optical emission from PSR-A's magnetosphere would be comparable to that of other Myr-old pulsars, thus suggesting that this parameter may not dramatically evolve over a timescale of a few Myr.

Safety of vitrectomy for floaters.

PubMed

Tan, H Stevie; Mura, Marco; Lesnik Oberstein, Sarit Y; Bijl, Heico M

2011-06-01

To assess the risks of vitrectomy for the removal of primary and secondary vitreous opacities. Retrospective, nonrandomized, interventional case series. We reviewed the results of 116 consecutive cases of vitrectomy for vitreous floaters. Eighty-six cases were primary and 30 cases were secondary floaters. Main outcome measures were the incidence of iatrogenic retinal breaks and postoperative rhegmatogenous retinal detachments. We found iatrogenic retinal breaks in 16.4% of operations. There was no statistically significant difference in risk between cases of primary and secondary floaters. Intraoperative posterior vitreous detachment induction was found to increase significantly the risk of breaks. Retinal detachment occurred in 3 cases (2.5%), all after operations for primary floaters. One case of complicated retinal detachment ended with a low visual acuity of hand movements. Cataract occurred in 50% of phakic cases. Transient postoperative hypotony was found after 5.2% of our operations, and transient postoperative high intraocular pressure was encountered in 7.8%. An intraoperative choroidal hemorrhage occurred in 1 case, which resolved spontaneously. The mean visual acuity improved from 0.20 to 0.13 logarithm of the minimal angle of resolution units. The risk profile of vitrectomy for floaters is comparable with that of vitrectomy for other elective indications. Retinal breaks are a common finding during surgery and treatment of these breaks is crucial for the prevention of postoperative retinal detachment. Patients considering surgery for floaters should be informed specifically about the risks involved. Copyright © 2011 Elsevier Inc. All rights reserved.

High Definition Clouds and Precipitation for advancing Climate Prediction (HD(CP)2): Large Eddy Simulation Study Over Germany

NASA Astrophysics Data System (ADS)

Dipankar, A.; Stevens, B. B.; Zängl, G.; Pondkule, M.; Brdar, S.

2014-12-01

The effect of clouds on large scale dynamics is represented in climate models through parameterization of various processes, of which the parameterization of shallow and deep convection are particularly uncertain. The atmospheric boundary layer, which controls the coupling to the surface, and which defines the scale of shallow convection, is typically 1 km in depth. Thus, simulations on a O(100 m) grid largely obviate the need for such parameterizations. By crossing this threshold of O(100m) grid resolution one can begin thinking of large-eddy simulation (LES), wherein the sub-grid scale parameterization have a sounder theoretical foundation. Substantial initiatives have been taken internationally to approach this threshold. For example, Miura et al., 2007 and Mirakawa et al., 2014 approach this threshold by doing global simulations, with (gradually) decreasing grid resolution, to understand the effect of cloud-resolving scales on the general circulation. Our strategy, on the other hand, is to take a big leap forward by fixing the resolution at O(100 m), and gradually increasing the domain size. We believe that breaking this threshold would greatly help in improving the parameterization schemes and reducing the uncertainty in climate predictions. To take this forward, the German Federal Ministry of Education and Research has initiated a project on HD(CP)2 that aims for a limited area LES at resolution O(100 m) using the new unified modeling system ICON (Zängl et al., 2014). In the talk, results from the HD(CP)2 evaluation simulation will be shown that targets high resolution simulation over a small domain around Jülich, Germany. This site is chosen because high resolution HD(CP)2 Observational Prototype Experiment took place in this region from 1.04.2013 to 31.05.2013, in order to critically evaluate the model. Nesting capabilities of ICON is used to gradually increase the resolution from the outermost domain, which is forced from the COSMO-DE data, to the innermost and finest resolution domain centered around Jülich (see Fig. 1 top panel). Furthermore, detailed analyses of the simulation results against the observation data will be presented. A reprsentative figure showing time series of column integrated water vapor (IWV) for both model and observation on 24.04.2013 is shown in bottom panel of Fig. 1.

Limits of applicability of the quasilinear approximation to the electrostatic wave-plasma interaction

NASA Astrophysics Data System (ADS)

Zacharegkas, Georgios; Isliker, Heinz; Vlahos, Loukas

2016-11-01

The limitation of the Quasilinear Theory (QLT) to describe the diffusion of electrons and ions in velocity space when interacting with a spectrum of large amplitude electrostatic Langmuir, Upper and Lower hybrid waves, is analyzed. We analytically and numerically estimate the threshold for the amplitude of the waves above which the QLT breaks down, using a test particle code. The evolution of the velocity distribution, the velocity-space diffusion coefficients, the driven current, and the heating of the particles are investigated, for the interaction with small and large amplitude electrostatic waves, that is, in both regimes, where QLT is valid and where it clearly breaks down.

Performance improvements of symmetry-breaking reflector structures in nonimaging devices

DOEpatents

Winston, Roland

2004-01-13

A structure and method for providing a broken symmetry reflector structure for a solar concentrator device. The component of the optical direction vector along the symmetry axis is conserved for all rays propagated through a translationally symmetric optical device. This quantity, referred to as the translational skew invariant, is conserved in rotationally symmetric optical systems. Performance limits for translationally symmetric nonimaging optical devices are derived from the distributions of the translational skew invariant for the optical source and for the target to which flux is to be transferred. A numerically optimized non-tracking solar concentrator utilizing symmetry-breaking reflector structures can overcome the performance limits associated with translational symmetry.

UT simulation using a fully automated 3D hybrid model: Application to planar backwall breaking defects inspection

NASA Astrophysics Data System (ADS)

Imperiale, Alexandre; Chatillon, Sylvain; Darmon, Michel; Leymarie, Nicolas; Demaldent, Edouard

2018-04-01

The high frequency models gathered in the CIVA software allow fast computations and provide satisfactory quantitative predictions in a wide range of situations. However, the domain of validity of these models is limited since they do not accurately predict the ultrasound response in configurations involving subwavelength complex phenomena. In addition, when modelling backwall breaking defects inspection, an important challenge remains to capture the propagation of the creeping waves that are generated at the critical angle. Hybrid models combining numerical and asymptotic methods have already been shown to be an effective strategy to overcome these limitations in 2D [1]. However, 3D simulations remain a crucial issue for industrial applications because of the computational cost of the numerical solver. A dedicated three dimensional high order finite element model combined with a domain decomposition method has been recently proposed to tackle 3D limitations [2]. In this communication, we will focus on the specific case of planar backwall breaking defects, with an adapted coupling strategy in order to efficiently model the propagation of creeping waves. Numerical and experimental validations will be proposed on various configurations.

Method for Cleanly and Precisely Breaking Off a Rock Core Using a Radial Compressive Force

NASA Technical Reports Server (NTRS)

Richardson, Megan; Lin, Justin

2011-01-01

The Mars Sample Return mission has the goal to drill, break off, and retain rock core samples. After some results gained from rock core mechanics testing, the realization that scoring teeth would cleanly break off the core after only a few millimeters of penetration, and noting that rocks are weak in tension, the idea was developed to use symmetric wedging teeth in compression to weaken and then break the core at the contact plane. This concept was developed as a response to the break-off and retention requirements. The wedges wrap around the estimated average diameter of the core to get as many contact locations as possible, and are then pushed inward, radially, through the core towards one another. This starts a crack and begins to apply opposing forces inside the core to propagate the crack across the plane of contact. The advantage is in the simplicity. Only two teeth are needed to break five varieties of Mars-like rock cores with limited penetration and reasonable forces. Its major advantage is that it does not require any length of rock to be attached to the parent in order to break the core at the desired location. Test data shows that some rocks break off on their own into segments or break off into discs. This idea would grab and retain a disc, push some discs upward and others out, or grab a segment, break it at the contact plane, and retain the portion inside of the device. It also does this with few moving parts in a simple, space-efficient design. This discovery could be implemented into a coring drill bit to precisely break off and retain any size rock core.

Large-scale Vortex Generation and Evolution in Short-crested Isolated Wave Breaking

NASA Astrophysics Data System (ADS)

Derakhti, M.; Kirby, J. T., Jr.

2016-12-01

Peregrine (1999), in discussing the effect of localization of wave energy dissipation as a generation mechanism for vorticity at the scale of individual waves, spurred a wave of study of vorticity dynamics and mixing processes in the wave-driven ocean. In deep water, the limited depth of penetration of breaking effects leads to the conceptual forcing of a "smoke-ring" resulting from the localized cross-section of impulsive forcing (Pizzo and Melville, 2013). In shallow water, depth limitations favor the generation of a quasi-two-dimensional field of vertical vortex structures, with a resulting inverse cascade of energy to low wavenumbers and the evolution of flows such as transient rip currents (Johnson and Pattiaratchi, 2006). In this study, we are examining a more detailed picture of the vorticity field evolving during a localized breaking event, with particular interest in the span from deep water to shallow water, with special attention to the transition from weak to strong bottom control. Using an LES/VOF model (Derakhti and Kirby, 2014), we examine the evolution of coherent vortex structures whose initial scales are determined by the width of the breaking region, and are much larger than the locally-controlled reverse horseshoe structures seen in typical studies of along-crest uniform breaking. We study the persistence of three-dimensionality of these structures and their contribution to the development of depth-integrated vertical vorticity, and comment on the suitability of 2D or quasi-3D models to represent nearshore flow fields.

Regional Climate Model Performance in Simulating Intra-seasonal and Interannual Variability of Indian Summer Monsoon

NASA Astrophysics Data System (ADS)

Bhatla, R.; Ghosh, Soumik; Mall, R. K.; Sinha, P.; Sarkar, Abhijit

2018-05-01

Establishment of Indian summer monsoon (ISM) rainfall passes through the different phases and is not uniformly distributed over the Indian subcontinent. This enhancement and reduction in daily rainfall anomaly over the Indian core monsoon region during peak monsoon season (i.e., July and August) are commonly termed as `active' and `break' phases of monsoon. The purpose of this study is to analyze REGional Climate Model (RegCM) results obtained using the most suitable convective parameterization scheme (CPS) to determine active/break phases of ISM. The model-simulated daily outgoing longwave radiation (OLR), mean sea level pressure (MSLP), and the wind at 850 hPa of spatial resolution of 0.5°× 0.5° are compared with NOAA, NCEP, and EIN15 data, respectively over the South-Asia Co-Ordinated Regional Climate Downscaling EXperiment (CORDEX) region. 25 years (1986-2010) composites of OLR, MSLP, and the wind at 850 hPa are considered from start to the dates of active/break phase and up to the end dates of active/break spell of monsoon. A negative/positive anomaly of OLR with active/break phase is found in simulations with CPSs Emanuel and Mix99 (Grell over land; Emanuel over ocean) over the core monsoon region as well as over Monsoon Convergence Zone (MCZ) of India. The appearance of monsoon trough during active phase over the core monsoon zone and its shifting towards the Himalayan foothills during break phase are also depicted well. Because of multi-cloud function over oceanic region and single cloud function over the land mass, the Mix99 CPSs perform well in simulating the synoptic features during the phases of monsoon.

A resolution congratulating the University of South Carolina baseball team for its gritty and record-breaking pursuit of back-to-back National Collegiate Athletic Association Division I Baseball National Championships.

THOMAS, 112th Congress

Sen. Graham, Lindsey [R-SC

2011-06-30

Senate - 06/30/2011 Submitted in the Senate, considered, and agreed to without amendment and with a preamble by Unanimous Consent. (All Actions) Tracker: This bill has the status Agreed to in SenateHere are the steps for Status of Legislation:

Breaking bad news: issues relating to nursing practice.

PubMed

Warnock, Clare

2014-07-15

The breaking of bad news was traditionally regarded to be the time when a doctor and nurse sat down with a patient and family members to provide information about, for example, a life-limiting diagnosis or a poor prognosis. However, breaking bad news is now generally accepted as a process, not a one-off event, and is considered to refer to any bad, sad or difficult information that alters patients' perceptions of their present and future. Nurses have an important role in the process of providing information and helping patients prepare for, receive, understand and cope with the bad news they have been given. This article aims to help nurses understand the process of breaking bad news and discuss the challenges and difficulties that nurses can face when they are involved with patients who have been given bad news. It also provides guidance with regard to preparing for breaking bad news, giving difficult information, responding to possible reactions, and supporting patients and their relatives after they have received bad news.

Increasing potential predictability of Indian Summer monsoon active and break spells

NASA Astrophysics Data System (ADS)

Mani, N. J.; Goswami, B.

2009-12-01

An understanding of the limit on potential predictability is crucial for developing appropriate tools for extended range prediction of active/break spells of Indian summer monsoon (ISM). The global low frequency changes in climate modulate the annual cycle of the ISM and can influence the intrinsic predictability limit of the ISM intraseasonal oscillations (ISOs). Using 104 year (1901-2004) long daily rainfall data, the change in potential predictability of active and break spells are estimated by an empirical method. Using an ISO index based on 10-90 day filtered precipitation, Goswami and Xavier (2003)showed that the monsoon breaks are intrinsically more predictable (20-25 days) than the active conditions (10-15 days. In the present study, employing the same method in 15 year sliding windows, we found that the potential predictability of both active and break spells have undergone a rapid increase during the recent three decades. The potential predictability of active spells has shown an increase from 1 week to 2 weeks while that for break spells increased from 2 weeks to 3 weeks. This result is interesting and intriguing in the backdrop of recent finding that the potential predictability of monsoon weather has decreased substantially over the same period compared to earlier decades due to increased potential instability of the atmosphere. The possible role of internal dynamics and external forcing in producing this change has been explored. The variance among peak active/break conditions shows a steady decrease over the years, indicating a lesser event to event variability in the magnitude of ISO peak phases in recent years. The ISO predictability may be closely linked to the error energy cascading from the synoptic scales and the interaction between these scales. Computation of nonlinear kinetic energy exchange between synoptic and ISO scales in frequency domain, also support the notion of ineffectual influence of synoptic scale errors on the ISO scale.Ref: Goswami, B N and P K Xavier, 2003,GRL. 30(18), 1966, doi:10.1029/2003GL017,810, 2003. Fig 1. Change in potential predictability of rainfall ISO through a 15 year sliding window. a) potential predictability for evolution from active to break b) potential predictability for evolution from break to active.

Highly efficient chiral resolution of DL-arginine by cocrystal formation followed by recrystallization under preferential-enrichment conditions.

PubMed

Iwama, Sekai; Kuyama, Kazunori; Mori, Yuko; Manoj, Kochunnoonny; Gonnade, Rajesh G; Suzuki, Katsuaki; Hughes, Colan E; Williams, P Andrew; Harris, Kenneth D M; Veesler, Stéphane; Takahashi, Hiroki; Tsue, Hirohito; Tamura, Rui

2014-08-11

An excellent chiral symmetry-breaking spontaneous enantiomeric resolution phenomenon, denoted preferential enrichment, was observed on recrystallization of the 1:1 cocrystal of dl-arginine and fumaric acid, which is classified as a racemic compound crystal with a high eutectic ee value (>95 %), under non-equilibrium crystallization conditions. On the basis of temperature-controlled video microscopy and in situ time-resolved solid-state (13) C NMR spectroscopic studies on the crystallization process, a new mechanism of phase transition that can induce preferential enrichment is proposed. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Negotiation techniques to resolve western water disputes

USGS Publications Warehouse

Lamb, Berton L.; Taylor, Jonathan G.

1990-01-01

There is a growing literature on the resolution of natural resources conflicts. Much of it is practical, focusing on guidelines for hands-on negotiation. This literature can be a guide in water conflicts. This is especially true for negotiations over new environmental values such as instream flow. The concepts of competitive, cooperative, and integrative styles of conflict resolution are applied to three cases of water resource bargaining. Lessons for the effective use of these ideas include: break a large number of parties into small working groups, approach value differences in small steps, be cautious in the presence of an attentive public, keeps decisions at the local level, and understand the opponent's interests.

Breaking the diffraction barrier using coherent anti-Stokes Raman scattering difference microscopy.

PubMed

Wang, Dong; Liu, Shuanglong; Chen, Yue; Song, Jun; Liu, Wei; Xiong, Maozhen; Wang, Guangsheng; Peng, Xiao; Qu, Junle

2017-05-01

We propose a method to improve the resolution of coherent anti-Stokes Raman scattering microscopy (CARS), and present a theoretical model. The proposed method, coherent anti-Stokes Raman scattering difference microscopy (CARS-D), is based on the intensity difference between two differently acquired images. One being the conventional CARS image, and the other obtained when the sample is illuminated by a doughnut shaped spot. The final super-resolution CARS-D image is constructed by intensity subtraction of these two images. However, there is a subtractive factor between them, and the theoretical model sets this factor to obtain the best imaging effect.

3D-glass molds for facile production of complex droplet microfluidic chips.

PubMed

Tovar, Miguel; Weber, Thomas; Hengoju, Sundar; Lovera, Andrea; Munser, Anne-Sophie; Shvydkiv, Oksana; Roth, Martin

2018-03-01

In order to leverage the immense potential of droplet microfluidics, it is necessary to simplify the process of chip design and fabrication. While polydimethylsiloxane (PDMS) replica molding has greatly revolutionized the chip-production process, its dependence on 2D-limited photolithography has restricted the design possibilities, as well as further dissemination of microfluidics to non-specialized labs. To break free from these restrictions while keeping fabrication straighforward, we introduce an approach to produce complex multi-height (3D) droplet microfluidic glass molds and subsequent chip production by PDMS replica molding. The glass molds are fabricated with sub-micrometric resolution using femtosecond laser machining technology, which allows directly realizing designs with multiple levels or even continuously changing heights. The presented technique significantly expands the experimental capabilities of the droplet microfluidic chip. It allows direct fabrication of multilevel structures such as droplet traps for prolonged observation and optical fiber integration for fluorescence detection. Furthermore, the fabrication of novel structures based on sloped channels (ramps) enables improved droplet reinjection and picoinjection or even a multi-parallelized drop generator based on gradients of confinement. The fabrication of these and other 3D-features is currently only available at such resolution by the presented strategy. Together with the simplicity of PDMS replica molding, this provides an accessible solution for both specialized and non-specialized labs to customize microfluidic experimentation and expand their possibilities.

A model study of sediment transport across the shelf break

NASA Astrophysics Data System (ADS)

Marchal, Olivier

2017-04-01

A variety of dynamical processes can contribute to the transport of material (e.g., particulate matter) across the shelf break - the region separating the continental shelf from the continental slope. Among these processes are (i) the reflection of internal waves on the outer shelf and upper slope, and (ii) the instability of hydrographic fronts, roughly aligned with isobaths, that are often present at the shelf break. On the one hand, internal waves reflecting on a sloping boundary can produce bottom shear stresses that are large enough to resuspend non-cohesive sediments into the water column. On the other hand, eddies shed from unstable shelf break fronts can incorporate into their core particle-rich waters from the outer shelf and upper slope, and transport these waters offshore. Here we present numerical experiments with a three-dimensional numerical model of ocean circulation and sediment transport, which illustrate the joint effect of internal waves and eddies on sediment transport across the shelf break. The model is based on the primitive equations and terrain-following coordinates. The model domain is square and idealized, comprising a flat continental shelf, a constant continental slope, and a flat abyssal basin. The model grid has O(1 km) horizontal resolution, so that (sub)mesoscale eddies observed in the vicinity of shelf breaks, such as south of New England, can be represented in detail. Internal waves are excited through the specification of a periodic variation in the across-slope component of velocity at the offshore boundary of the domain, and eddies are generated from the baroclinic instability of a shelf break jet that is initially in strict thermal wind balance. Numerical experiments are conducted that are characterized by (i) different slopes of internal wave characteristics relative to the continental slope, representing sub-critical, critical, and super-critical regimes, and (ii) different values for the dimensionless ratios that emerge from the linear stability analysis of shelf break fronts. Emphasis is placed on the physical conditions that are conducive to the formation and maintenance of bottom and intermediate nepheloid layers - the particle-rich layers that are often observed near oceanic margins in the traces of optical instruments.

Ultra-high speed visualization of the flashing instability under vacuum conditions

NASA Astrophysics Data System (ADS)

Hernández Sánchez, Jose Federico; Al-Ghamdi, Tariq; Thoroddsen, Sigurdur T.

2017-11-01

We investigated experimentally the flashing instability of a jet of perfluoro-n-hexane (PFnH) released into a low-pressure environment. Using a ultra-high speed camera we observed the jet fragmentation occurring close to the nozzle. Using a fixed total driving pressure, we decreased systematically the vacuum pressure, investigating the transition from a laminar jet to a fully flashing jet. Our high temporal resolution allowed to visualize the detailed dynamics of external flash-boiling for the first time. We identified different mechanisms of jet break-up. At chamber pressures lower than the vapor pressure the laminar jet evolves to a meandering stream. In this stage, bubbles start to nucleate and violently expand upstream the nozzle. At lower vacuum pressures the initially cylindrical jet elongates, forming a liquid sheet that breaks in branches and later in drops. At very low pressures both mechanisms are responsible for the jet breaking. We calculated the size distribution of the ejected droplets, their individual trajectories, velocities as well as the spray angle as a function of the dimensionless vacuum pressure.

Towards breaking the spatial resolution barriers: An optical flow and super-resolution approach for sea ice motion estimation

NASA Astrophysics Data System (ADS)

Petrou, Zisis I.; Xian, Yang; Tian, YingLi

2018-04-01

Estimation of sea ice motion at fine scales is important for a number of regional and local level applications, including modeling of sea ice distribution, ocean-atmosphere and climate dynamics, as well as safe navigation and sea operations. In this study, we propose an optical flow and super-resolution approach to accurately estimate motion from remote sensing images at a higher spatial resolution than the original data. First, an external example learning-based super-resolution method is applied on the original images to generate higher resolution versions. Then, an optical flow approach is applied on the higher resolution images, identifying sparse correspondences and interpolating them to extract a dense motion vector field with continuous values and subpixel accuracies. Our proposed approach is successfully evaluated on passive microwave, optical, and Synthetic Aperture Radar data, proving appropriate for multi-sensor applications and different spatial resolutions. The approach estimates motion with similar or higher accuracy than the original data, while increasing the spatial resolution of up to eight times. In addition, the adopted optical flow component outperforms a state-of-the-art pattern matching method. Overall, the proposed approach results in accurate motion vectors with unprecedented spatial resolutions of up to 1.5 km for passive microwave data covering the entire Arctic and 20 m for radar data, and proves promising for numerous scientific and operational applications.

Fatigueless response of spider draglines in cyclic torsion facilitated by reversible molecular deformation

NASA Astrophysics Data System (ADS)

Kumar, Bhupesh; Singh, Kamal P.

2014-11-01

We demonstrate that spider draglines exhibit a fatigueless response in extreme cyclic torsion up to its breaking limit. The well defined Raman bands at 1095 and 1245 cm-1 shifted linearly towards lower wavenumbers versus increasing twist in both clockwise and counter-clockwise directions. Under thousands of continuous loading cycles of twist strain approaching its breaking limit, all the Raman bands were preserved and the characteristic Raman peak shifts were found to be reversible. Besides, nanoscale surface profile of the worked silk appeared as good as the pristine silk. This unique fatigueless twist response of draglines, facilitated by reversible deformation of protein molecules, could find applications in durable miniatured devices.

Chiral symmetry breaking and the spin content of the ρ and ρ‧ mesons

NASA Astrophysics Data System (ADS)

Glozman, L. Ya.; Lang, C. B.; Limmer, M.

2011-11-01

Using interpolators with different SU(2)L × SU(2)R transformation properties we study the chiral symmetry and spin contents of the ρ and ρ‧ mesons in lattice simulations with dynamical quarks. A ratio of couplings of the qbarγi τq and qbarσ0i τq interpolators to a given meson state at different resolution scales tells one about the degree of chiral symmetry breaking in the meson wave function at these scales. Using a Gaussian gauge invariant smearing of the quark fields in the interpolators, we are able to extract the chiral content of mesons up to the infrared resolution of ∼ 1 fm. In the ground state ρ meson the chiral symmetry is strongly broken with comparable contributions of both the (0 , 1) + (1 , 0) and (1 / 2 , 1 / 2) b chiral representations with the former being the leading contribution. In contrast, in the ρ‧ meson the degree of chiral symmetry breaking is manifestly smaller and the leading representation is (1 / 2 , 1 / 2) b. Using a unitary transformation from the chiral basis to the LJ2S+1 basis, we are able to define and measure the angular momentum content of mesons in the rest frame. This definition is different from the traditional one which uses parton distributions in the infinite momentum frame. The ρ meson is practically a 3S1 state with no obvious trace of a "spin crisis". The ρ‧ meson has a sizeable contribution of the 3D1 wave, which implies that the ρ‧ meson cannot be considered as a pure radial excitation of the ρ meson.

Spatial and temporal patterns of sea ice variations in Vilkitsky strait, Russian High Arctic

NASA Astrophysics Data System (ADS)

Ci, T.; Cheng, X.; Hui, F.

2013-12-01

The Arctic Ocean has been greatly affected by climate change. Future predications show an even more drastic reduction of the ice cap which will open new areas for the exploration of natural resources and maritime transportation.Shipping through the Arctic Ocean via the Northern Sea Route (NSR) could save about 40% of the sailing distance from Asia (Yokohama) to Europe (Rotterdam) compared to the traditional route via the Suez Canal. Vilkitsky strait is the narrowest and northest portion of the Northern Sea Route with heaviest traffic between the Taimyr Peninsular and the Severnaya Zemlya archipelago. The preliminary results of sea ice variations are presented by using moderate-resolution imaging spectro radiometer(MODIS) data with 250-m resolution in the Vilkitsky strait during 2009-2012. Temporally, the first rupture on sea ice in Vilkitsky strait usually comes up in April and sea ice completely break into pieces in early June. The strait would be ice-free between August and late September. The frequency of ice floes grows while temperature falls down in October. There are always one or two months suitable for transport. Spatially, Sea ice on Laptev sea side breaks earlier than that of Kara sea side while sea ice in central of strait breaks earlier than in shoreside. The phenomena are directly related with the direction of sea wind and ocean current. In summmary, study on Spatial and temporal patterns in this area is significant for the NSR. An additional research issue to be tackled is to seeking the trends of ice-free duration in the context of global warming. Envisat ASAR data will also be used in this study.

Microparticles controllable accumulation, arrangement, and spatial shaping performed by tapered-fiber-based laser-induced convection flow.

PubMed

Zhang, Yu; Lei, Jiaojie; Zhang, Yaxun; Liu, Zhihai; Zhang, Jianzhong; Yang, Xinghua; Yang, Jun; Yuan, Libo

2017-10-30

The ability to arrange cells and/or microparticles into the desired pattern is critical in biological, chemical, and metamaterial studies and other applications. Researchers have developed a variety of patterning techniques, which either have a limited capacity to simultaneously trap massive particles or lack the spatial resolution necessary to manipulate individual particle. Several approaches have been proposed that combine both high spatial selectivity and high throughput simultaneously. However, those methods are complex and difficult to fabricate. In this article, we propose and demonstrate a simple method that combines the laser-induced convection flow and fiber-based optical trapping methods to perform both regular and special spatial shaping arrangement. Essentially, we combine a light field with a large optical intensity gradient distribution and a thermal field with a large temperature gradient distribution to perform the microparticles shaping arrangement. The tapered-fiber-based laser-induced convection flow provides not only the batch manipulation of massive particles, but also the finer manipulation of special one or several particles, which break out the limit of single-fiber-based massive/individual particles photothermal manipulation. The combination technique allows for microparticles quick accumulation, single-layer and multilayer arrangement; special spatial shaping arrangement/adjustment, and microparticles sorting.

Solar Adaptive Optics.

PubMed

Rimmele, Thomas R; Marino, Jose

Adaptive optics (AO) has become an indispensable tool at ground-based solar telescopes. AO enables the ground-based observer to overcome the adverse effects of atmospheric seeing and obtain diffraction limited observations. Over the last decade adaptive optics systems have been deployed at major ground-based solar telescopes and revitalized ground-based solar astronomy. The relatively small aperture of solar telescopes and the bright source make solar AO possible for visible wavelengths where the majority of solar observations are still performed. Solar AO systems enable diffraction limited observations of the Sun for a significant fraction of the available observing time at ground-based solar telescopes, which often have a larger aperture than equivalent space based observatories, such as HINODE. New ground breaking scientific results have been achieved with solar adaptive optics and this trend continues. New large aperture telescopes are currently being deployed or are under construction. With the aid of solar AO these telescopes will obtain observations of the highly structured and dynamic solar atmosphere with unprecedented resolution. This paper reviews solar adaptive optics techniques and summarizes the recent progress in the field of solar adaptive optics. An outlook to future solar AO developments, including a discussion of Multi-Conjugate AO (MCAO) and Ground-Layer AO (GLAO) will be given. Supplementary material is available for this article at 10.12942/lrsp-2011-2.

European Conference on Advanced Materials and Processes Held in Aachen, Federal Republic of Germany on November 22-24, 1989

DTIC Science & Technology

1989-11-24

proceedings after the conference (the proceedings will consist of 3 volumes), extended abstracts, welcome reception, poster buffet, snack on Friday...poster buffet, snack on Friday, refreshments during official breaks. (This fee does not include the proceedings). " A limited number of registrations...buffet, snack on Friday, refreshments during the official breaks. (This fee does not include the proceedings). " Accompanying persons who are not

Flow and turbulence structure in a hypertidal estuary with the world's biggest tidal bore

NASA Astrophysics Data System (ADS)

Tu, Junbiao; Fan, Daidu

2017-04-01

Turbulent and flow structure associated with breaking tidal bores are deliberately investigated on the basis of field measurements. High-resolution velocity and hydrographic data are collected in the middle Qiantang Estuary by a vertical array of acoustic Doppler velocimeters and optical backscatter sensors, collaborated with a bottom-mounted acoustic Doppler current profiler. Besides obvious variations in diurnal and spring-neap tidal cycles, the estuarine dynamics is featured by extreme asymmetry in flood and ebb tides. The flood tide is abnormally accelerated to generate tidal bores at the first 10 min or more, with breaking or undular configurations at the front. The occurrence of peak flow velocity, turbulent kinetic energy (TKE), and TKE dissipation rate (ɛ) is definitely associated with breaking bores, with their values several times to 2 orders of magnitude larger than the corresponding secondary peak values during the maximum ebb flows. Flow and turbulence dynamics are significantly affected by the tidal-bore Froude number. A sandwich ɛ structure is clear exhibited with the maximum value at the surface, secondary maximum near the bed, and the minimum at the intermediate. Dual TKE sources are indicated by an approximate local balance between shear production and dissipation near the bottom, and a top-down TKE dissipation using the modified Froude scaling in the vertical water column. The highly elevated dissipation by breaking bores is comparable to that by intense breaking waves in the surf zone, and the former potentially penetrates the entire water column to produce extreme sediment-resuspension events in combination with intense bottom shear stress.

Cosmology of biased discrete symmetry breaking

NASA Technical Reports Server (NTRS)

Gelmini, Graciela B.; Gleiser, Marcelo; Kolb, Edward W.

1988-01-01

The cosmological consequences of spontaneous breaking of an approximate discrete symmetry are studied. The breaking leads to formation of proto-domains of false and true vacuum separated by domain walls of thickness determined by the mass scale of the model. The cosmological evolution of the walls is extremely sensitive to the magnitude of the biasing; several scenarios are possible, depending on the interplay between the surface tension on the walls and the volume pressure from the biasing. Walls may disappear almost immediately after they form, or may live long enough to dominate the energy density of the Universe and cause power-law inflation. Limits are obtained on the biasing that characterizes each possible scenario.

Helicase Stepping Investigated with One-Nucleotide Resolution Fluorescence Resonance Energy Transfer

NASA Astrophysics Data System (ADS)

Lin, Wenxia; Ma, Jianbing; Nong, Daguan; Xu, Chunhua; Zhang, Bo; Li, Jinghua; Jia, Qi; Dou, Shuoxing; Ye, Fangfu; Xi, Xuguang; Lu, Ying; Li, Ming

2017-09-01

Single-molecule Förster resonance energy transfer is widely applied to study helicases by detecting distance changes between a pair of dyes anchored to overhangs of a forked DNA. However, it has been lacking single-base pair (1-bp) resolution required for revealing stepping kinetics of helicases. We designed a nanotensioner in which a short DNA is bent to exert force on the overhangs, just as in optical or magnetic tweezers. The strategy improved the resolution of Förster resonance energy transfer to 0.5 bp, high enough to uncover differences in DNA unwinding by yeast Pif1 and E. coli RecQ whose unwinding behaviors cannot be differentiated by currently practiced methods. We found that Pif1 exhibits 1-bp-stepping kinetics, while RecQ breaks 1 bp at a time but sequesters the nascent nucleotides and releases them randomly. The high-resolution data allowed us to propose a three-parameter model to quantitatively interpret the apparently different unwinding behaviors of the two helicases which belong to two superfamilies.

High-resolution bottom-loss estimation using the ambient-noise vertical coherence function.

PubMed

Muzi, Lanfranco; Siderius, Martin; Quijano, Jorge E; Dosso, Stan E

2015-01-01

The seabed reflection loss (shortly "bottom loss") is an important quantity for predicting transmission loss in the ocean. A recent passive technique for estimating the bottom loss as a function of frequency and grazing angle exploits marine ambient noise (originating at the surface from breaking waves, wind, and rain) as an acoustic source. Conventional beamforming of the noise field at a vertical line array of hydrophones is a fundamental step in this technique, and the beamformer resolution in grazing angle affects the quality of the estimated bottom loss. Implementation of this technique with short arrays can be hindered by their inherently poor angular resolution. This paper presents a derivation of the bottom reflection coefficient from the ambient-noise spatial coherence function, and a technique based on this derivation for obtaining higher angular resolution bottom-loss estimates. The technique, which exploits the (approximate) spatial stationarity of the ambient-noise spatial coherence function, is demonstrated on both simulated and experimental data.

Development of a Telescope for Medium-Energy Gamma-Ray Astronomy

NASA Technical Reports Server (NTRS)

Hunter, Stanley D.

2010-01-01

Since the launch of AGILE and FERMI, the scientific progress in high-energy (E(sub gamma) greater than approximately 200 MeV) gamma-ray science has been, and will continue to be dramatic. Both of these telescopes cover a broad energy range from approximately 20 MeV to greater than 10 GeV. However, neither instrument is optimized for observations below approximately 200 MeV where many astrophysical objects exhibit unique, transitory behavior, such as spectral breaks, bursts, and flares. Hence, while significant progress from current observations is expected, there will nonetheless remain a significant sensitivity gap in the medium-energy (approximately 0.1-200 MeV) regime; the lower end of this range remains largely unexplored whereas the upper end will allow comparison with FERMI data. Tapping into this unexplored regime requires significant improvements in sensitivity. A major emphasis of modern detector development, with the goal of providing significant improvements in sensitivity in the medium-energy regime, focuses on high-resolution electron tracking. The Three-Dimensional Track Imager (3-DTI) technology being developed at GSFC provides high resolution tracking of the electron-positron pair from gamma-ray interactions from 5 to 200 MeV. The 3-DTI consists of a time projection chamber (TPC) and 2-D cross-strip microwell detector (MWD). The low-density and homogeneous design of the 3-DTI, offers unprecedented sensitivity by providing angular resolution near the kinematic limit. Electron tracking also enables measurement of gamma-ray polarization, a new tool to study astrophysical phenomenon. We describe the design, fabrication, and performance of a 30x30x30 cubic centimeters 3-DTI detector prototype of a medium-energy gamma-ray telescope.

Development of a Telescope for Medium-Energy Gamma-ray Astronomy

NASA Technical Reports Server (NTRS)

Sunter, Stan

2012-01-01

Since the launch of AGILE and FERMI, the scientific progress in high-energy (Eg greater than approximately 200 MeV) gamma-ray science has been, and will continue to be dramatic. Both of these telescopes cover a broad energy range from approximately 20 MeV to greater than 10 GeV. However, neither instrument is optimized for observations below approximately 200 MeV where many astrophysical objects exhibit unique, transitory behavior, such as spectral breaks, bursts, and flares. Hence, while significant progress from current observations is expected, there will nonetheless remain a significant sensitivity gap in the medium-energy (approximately 0.1-200 MeV) regime; the lower end of this range remains largely unexplored whereas the upper end will allow comparison with FERMI data. Tapping into this unexplored regime requires significant improvements in sensitivity. A major emphasis of modern detector development, with the goal of providing significant improvements in sensitivity in the medium-energy regime, focuses on high-resolution electron tracking. The Three-Dimensional Track Imager (3-DTI) technology being developed at GSFC provides high resolution tracking of the electron-positron pair from gamma-ray interactions from 5 to 200 MeV. The 3-DTI consists of a time projection chamber (TPC) and 2-D cross-strip microwell detector (MWD). The low-density and homogeneous design of the 3-DTI, offers unprecedented sensitivity by providing angular resolution near the kinematic limit. Electron tracking also enables measurement of gamma-ray polarization, a new tool to study astrophysical phenomenon. We describe the design, fabrication, and performance of a 30x30x30 cm3 3-DTI detector prototype of a medium-energy gamma-ray telescope.

Processes of 30-90 days sea surface temperature variability in the northern Indian Ocean during boreal summer

NASA Astrophysics Data System (ADS)

Vialard, J.; Jayakumar, A.; Gnanaseelan, C.; Lengaigne, M.; Sengupta, D.; Goswami, B. N.

2012-05-01

During summer, the northern Indian Ocean exhibits significant atmospheric intraseasonal variability associated with active and break phases of the monsoon in the 30-90 days band. In this paper, we investigate mechanisms of the Sea Surface Temperature (SST) signature of this atmospheric variability, using a combination of observational datasets and Ocean General Circulation Model sensitivity experiments. In addition to the previously-reported intraseasonal SST signature in the Bay of Bengal, observations show clear SST signals in the Arabian Sea related to the active/break cycle of the monsoon. As the atmospheric intraseasonal oscillation moves northward, SST variations appear first at the southern tip of India (day 0), then in the Somali upwelling region (day 10), northern Bay of Bengal (day 19) and finally in the Oman upwelling region (day 23). The Bay of Bengal and Oman signals are most clearly associated with the monsoon active/break index, whereas the relationship with signals near Somali upwelling and the southern tip of India is weaker. In agreement with previous studies, we find that heat flux variations drive most of the intraseasonal SST variability in the Bay of Bengal, both in our model (regression coefficient, 0.9, against ~0.25 for wind stress) and in observations (0.8 regression coefficient); ~60% of the heat flux variation is due do shortwave radiation and ~40% due to latent heat flux. On the other hand, both observations and model results indicate a prominent role of dynamical oceanic processes in the Arabian Sea. Wind-stress variations force about 70-100% of SST intraseasonal variations in the Arabian Sea, through modulation of oceanic processes (entrainment, mixing, Ekman pumping, lateral advection). Our ~100 km resolution model suggests that internal oceanic variability (i.e. eddies) contributes substantially to intraseasonal variability at small-scale in the Somali upwelling region, but does not contribute to large-scale intraseasonal SST variability due to its small spatial scale and random phase relation to the active-break monsoon cycle. The effect of oceanic eddies; however, remains to be explored at a higher spatial resolution.

Imaging of the Field of 4C41.17 Below the Lyman Limit

NASA Technical Reports Server (NTRS)

Lacy, Mark; Rawlings, Steve

1997-01-01

Imaging of zeta greater than or equal to 3.4 radio galaxy fields below the Lyman continuum wavelength allows companion galaxies to be identified on the basis of red colors across the wavelength of redshifted Ly(alpha) and very red colors across the redshifted Lyman continuum. These arise due to a combination of absorption by intervening Ly(alpha) forest and Lyman-limit systems, and intrinsic Lyman-limit breaks in the galaxy spectral energy distribution caused by an Hi screen or breaks in stellar spectra. As a pilot study, we have imaged the field of the zeta = 3.8 radio galaxy 4C41.17 in U, V and R with the Auxiliary Port of the WHT. We find a number of potential companion galaxies, which require confirmation via spectroscopy or narrow-band imaging. The Lyman-limit in the spectrum of the radio galaxy itself and its implications for the origin of the UV flux is also discussed.

Discrete symmetry breaking and baryon currents in U(N) and SU(N) gauge theories

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

Lucini, B.; Patella, A.

2009-06-15

In SU(N) gauge theories with fermions in the fundamental or in a two-index (either symmetric or antisymmetric) representation formulated on a manifold with at least one compact dimension with nontrivial holonomy the discrete symmetries C, P, and T are broken at small enough size of the compact direction(s) for certain values of N. We show that for those N in the broken phase a nonzero baryon current wrapping in the compact direction exists, which provides a measurable observable for the breaking of C, P, and T. We prove that in all cases where the current is absent there is nomore » breaking of those discrete symmetries. This includes the limit N{yields}{infinity} of the SU(N) gauge theory with symmetric or antisymmetric fermions and U(N) gauge theory at any value of N. We then argue that the component of the baryon current in the compact direction is the physical order parameter for C, P, and T breaking due to the breaking of Lorentz invariance.« less

Effect of current on spectrum of breaking waves in water of finite depth

NASA Technical Reports Server (NTRS)

Tung, C. C.; Huang, N. E.

1987-01-01

This paper presents an approximate method to compute the mean value, the mean square value and the spectrum of waves in water of finite depth taking into account the effect of wave breaking with or without the presence of current. It is assumed that there exists a linear and Gaussian ideal wave train whose spectrum is first obtained using the wave energy flux balance equation without considering wave breaking. The Miche wave breaking criterion for waves in finite water depth is used to limit the wave elevation and establish an expression for the breaking wave elevation in terms of the elevation and its second time derivative of the ideal waves. Simple expressions for the mean value, the mean square value and the spectrum are obtained. These results are applied to the case in which a deep water unidirectional wave train, propagating normally towards a straight shoreline over gently varying sea bottom of parallel and straight contours, encounters an adverse steady current whose velocity is assumed to be uniformly distributed with depth. Numerical results are obtained and presented in graphical form.

Large-eddy simulation of cavitating nozzle flow and primary jet break-up

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

Örley, F., E-mail: felix.oerley@aer.mw.tum.de; Trummler, T.; Mihatsch, M. S.

We employ a barotropic two-phase/two-fluid model to study the primary break-up of cavitating liquid jets emanating from a rectangular nozzle, which resembles a high aspect-ratio slot flow. All components (i.e., gas, liquid, and vapor) are represented by a homogeneous mixture approach. The cavitating fluid model is based on a thermodynamic-equilibrium assumption. Compressibility of all phases enables full resolution of collapse-induced pressure wave dynamics. The thermodynamic model is embedded into an implicit large-eddy simulation (LES) environment. The considered configuration follows the general setup of a reference experiment and is a generic reproduction of a scaled-up fuel injector or control valve asmore » found in an automotive engine. Due to the experimental conditions, it operates, however, at significantly lower pressures. LES results are compared to the experimental reference for validation. Three different operating points are studied, which differ in terms of the development of cavitation regions and the jet break-up characteristics. Observed differences between experimental and numerical data in some of the investigated cases can be caused by uncertainties in meeting nominal parameters by the experiment. The investigation reveals that three main mechanisms promote primary jet break-up: collapse-induced turbulent fluctuations near the outlet, entrainment of free gas into the nozzle, and collapse events inside the jet near the liquid-gas interface.« less

X-ray Variability Characteristics of the Narrow line SEYFERT 1 MKN 766 I: Energy Dependent Timing Properties

NASA Technical Reports Server (NTRS)

Markowitz, A.; Turner, T. J.; Papadakis, I.; Arevalo, P.; Reeves, J. N.; Miller, L.

2007-01-01

We present the energy-dependent power spectral density (PSD) and cross-spectral properties of Mkn 766 obtained from a six-revolution XMM-Newton observation in 2005. The resulting PSDs, which have highest temporal frequency resolution for an AGN PSD to date, show breaks which increase in temporal frequency as photon energy increases; break frequencies differ by an average of approx.0.4 in the log between the softest and hardest bands. The consistency of the 2001 and 2005 observations variability properties, namely PSD shapes and the linear rms-flux relation, suggests the 2005 observation is simply a low-flux extension of the 2001 observation. The coherence function is measured to be approx.0.6-0.9 at temporal frequencies below the PSD break, and is lower for relatively larger energy band separation; coherence also drops significantly towards zero above the PSD break frequency. Temporal frequency-dependent soft-to-hard time lags are detected in this object for the first time: lags increase towards longer time scales and as energy separation increases. Cross-spectral properties are the thus consistent with previous measurements for Mkn 766 (Vaughan & Fabian 2003) and other accreting black hole systems. The results are discussed in the context of several variability models, including those based on inwardly-propagating viscosity variations in the accretion disk.

Regional simulation of Indian summer monsoon intraseasonal oscillations at gray-zone resolution

NASA Astrophysics Data System (ADS)

Chen, Xingchao; Pauluis, Olivier M.; Zhang, Fuqing

2018-01-01

Simulations of the Indian summer monsoon by the cloud-permitting Weather Research and Forecasting (WRF) model at gray-zone resolution are described in this study, with a particular emphasis on the model ability to capture the monsoon intraseasonal oscillations (MISOs). Five boreal summers are simulated from 2007 to 2011 using the ERA-Interim reanalysis as the lateral boundary forcing data. Our experimental setup relies on a horizontal grid spacing of 9 km to explicitly simulate deep convection without the use of cumulus parameterizations. When compared to simulations with coarser grid spacing (27 km) and using a cumulus scheme, the 9 km simulations reduce the biases in mean precipitation and produce more realistic low-frequency variability associated with MISOs. Results show that the model at the 9 km gray-zone resolution captures the salient features of the summer monsoon. The spatial distributions and temporal evolutions of monsoon rainfall in the WRF simulations verify qualitatively well against observations from the Tropical Rainfall Measurement Mission (TRMM), with regional maxima located over Western Ghats, central India, Himalaya foothills, and the west coast of Myanmar. The onset, breaks, and withdrawal of the summer monsoon in each year are also realistically captured by the model. The MISO-phase composites of monsoon rainfall, low-level wind, and precipitable water anomalies in the simulations also agree qualitatively with the observations. Both the simulations and observations show a northeastward propagation of the MISOs, with the intensification and weakening of the Somali Jet over the Arabian Sea during the active and break phases of the Indian summer monsoon.

Using electric current to surpass the microstructure breakup limit

PubMed Central

Qin, Rongshan

2017-01-01

The elongated droplets and grains can break up into smaller ones. This process is driven by the interfacial free energy minimization, which gives rise to a breakup limit. We demonstrated in this work that the breakup limit can be overpassed drastically by using electric current to interfere. Electric current free energy is dependent on the microstructure configuration. The breakup causes the electric current free energy to reduce in some cases. This compensates the increment of interfacial free energy during breaking up and enables the processing to achieve finer microstructure. With engineering practical electric current parameters, our calculation revealed a significant increment of the obtainable number of particles, showing electric current a powerful microstructure refinement technology. The calculation is validated by our experiments on the breakup of Fe3C-plates in Fe matrix. Furthermore, there is a parameter range that electric current can drive spherical particles to split into smaller ones. PMID:28120919

Atomic resolution ultrafast scanning tunneling microscope with scan rate breaking the resonant frequency of a quartz tuning fork resonator.

PubMed

Li, Quanfeng; Lu, Qingyou

2011-05-01

We present an ultra-fast scanning tunneling microscope with atomic resolution at 26 kHz scan rate which surpasses the resonant frequency of the quartz tuning fork resonator used as the fast scan actuator. The main improvements employed in achieving this new record are (1) fully low voltage design (2) independent scan control and data acquisition, where the tuning fork (carrying a tip) is blindly driven to scan by a function generator with the scan voltage and tunneling current (I(T)) being measured as image data (this is unlike the traditional point-by-point move and measure method where data acquisition and scan control are switched many times).

A Test of Thick-Target Nonuniform Ionization as an Explanation for Breaks in Solar Flare Hard X-Ray Spectra

NASA Technical Reports Server (NTRS)

Holman, gordon; Dennis Brian R.; Tolbert, Anne K.; Schwartz, Richard

2010-01-01

Solar nonthermal hard X-ray (HXR) flare spectra often cannot be fitted by a single power law, but rather require a downward break in the photon spectrum. A possible explanation for this spectral break is nonuniform ionization in the emission region. We have developed a computer code to calculate the photon spectrum from electrons with a power-law distribution injected into a thick-target in which the ionization decreases linearly from 100% to zero. We use the bremsstrahlung cross-section from Haug (1997), which closely approximates the full relativistic Bethe-Heitler cross-section, and compare photon spectra computed from this model with those obtained by Kontar, Brown and McArthur (2002), who used a step-function ionization model and the Kramers approximation to the cross-section. We find that for HXR spectra from a target with nonuniform ionization, the difference (Delta-gamma) between the power-law indexes above and below the break has an upper limit between approx.0.2 and 0.7 that depends on the power-law index delta of the injected electron distribution. A broken power-law spectrum with a. higher value of Delta-gamma cannot result from nonuniform ionization alone. The model is applied to spectra obtained around the peak times of 20 flares observed by the Ramaty High Energy Solar Spectroscopic Imager (RHESSI from 2002 to 2004 to determine whether thick-target nonuniform ionization can explain the measured spectral breaks. A Monte Carlo method is used to determine the uncertainties of the best-fit parameters, especially on Delta-gamma. We find that 15 of the 20 flare spectra require a downward spectral break and that at least 6 of these could not be explained by nonuniform ionization alone because they had values of Delta-gamma with less than a 2.5% probability of being consistent with the computed upper limits from the model. The remaining 9 flare spectra, based on this criterion, are consistent with the nonuniform ionization model.

DNA Resection at Chromosome Breaks Promotes Genome Stability by Constraining Non-Allelic Homologous Recombination

PubMed Central

Koshland, Douglas

2012-01-01

DNA double-strand breaks impact genome stability by triggering many of the large-scale genome rearrangements associated with evolution and cancer. One of the first steps in repairing this damage is 5′→3′ resection beginning at the break site. Recently, tools have become available to study the consequences of not extensively resecting double-strand breaks. Here we examine the role of Sgs1- and Exo1-dependent resection on genome stability using a non-selective assay that we previously developed using diploid yeast. We find that Saccharomyces cerevisiae lacking Sgs1 and Exo1 retains a very efficient repair process that is highly mutagenic to genome structure. Specifically, 51% of cells lacking Sgs1 and Exo1 repair a double-strand break using repetitive sequences 12–48 kb distal from the initial break site, thereby generating a genome rearrangement. These Sgs1- and Exo1-independent rearrangements depend partially upon a Rad51-mediated homologous recombination pathway. Furthermore, without resection a robust cell cycle arrest is not activated, allowing a cell with a single double-strand break to divide before repair, potentially yielding multiple progeny each with a different rearrangement. This profusion of rearranged genomes suggests that cells tolerate any dangers associated with extensive resection to inhibit mutagenic pathways such as break-distal recombination. The activation of break-distal recipient repeats and amplification of broken chromosomes when resection is limited raise the possibility that genome regions that are difficult to resect may be hotspots for rearrangements. These results may also explain why mutations in resection machinery are associated with cancer. PMID:22479212

Origins Space Telescope: Breaking the Confusion Limit

NASA Astrophysics Data System (ADS)

Wright, Edward L.; Origins Space Telescope Science and Technology Definition Team

2018-01-01

The Origins Space Telescope (OST) is the mission concept for the Far-Infrared Surveyor, one of the four science and technology definition studies of NASA Headquarters for the 2020 Astronomy and Astrophysics Decadal survey. Origins will enable flagship-quality general observing programs led by the astronomical community in the 2030s.OST will have a background-limited sensitivity for a background 27,000 times lower than the Herschel background caused by thermal emission from Herschel's warm telescope. For continuum observations the confusion limit in a diffraction-limited survey can be reached in very short integration times at longer far-infrared wavelengths. But the confusion limit can be pierced for both the nearest and the farthest objects to be observed by OST. For outer the Solar System the targets' motion across the sky will provide a clear signature in surveys repeated after an interval of days to months. This will provide a size-frequency distribution of TNOs that is not biased toward high albedo objects.For the distant Universe the first galaxies and the first metals will provide a third dimension of spectral information that can be measured with a long-slit, medium resolution spectrograph. This will allow 3Dmapping to measure source densities as a function of redshift. The continuum shape associated with sourcesat different redshifts can be derived from correlation analyses of these 3D maps.Fairly large sky areas can be scanned by moving the spacecraft at a constant angular rate perpendicular to the orientation of the long slit of the spectrograph, avoiding the high overhead of step-and-stare surveying with a large space observatory.We welcome you to contact the Science and Technology Definition Team (STDT) with your science needs and ideas by emailing us at ost_info@lists.ipac.caltech.edu

You Spin my Head Right Round: Threshold of Limited Immersion for Rotation Gains in Redirected Walking.

PubMed

Schmitz, Patric; Hildebrandt, Julian; Valdez, Andre Calero; Kobbelt, Leif; Ziefle, Martina

2018-04-01

In virtual environments, the space that can be explored by real walking is limited by the size of the tracked area. To enable unimpeded walking through large virtual spaces in small real-world surroundings, redirection techniques are used. These unnoticeably manipulate the user's virtual walking trajectory. It is important to know how strongly such techniques can be applied without the user noticing the manipulation-or getting cybersick. Previously, this was estimated by measuring a detection threshold (DT) in highly-controlled psychophysical studies, which experimentally isolate the effect but do not aim for perceived immersion in the context of VR applications. While these studies suggest that only relatively low degrees of manipulation are tolerable, we claim that, besides establishing detection thresholds, it is important to know when the user's immersion breaks. We hypothesize that the degree of unnoticed manipulation is significantly different from the detection threshold when the user is immersed in a task. We conducted three studies: a) to devise an experimental paradigm to measure the threshold of limited immersion (TLI), b) to measure the TLI for slowly decreasing and increasing rotation gains, and c) to establish a baseline of cybersickness for our experimental setup. For rotation gains greater than 1.0, we found that immersion breaks quite late after the gain is detectable. However, for gains lesser than 1.0, some users reported a break of immersion even before established detection thresholds were reached. Apparently, the developed metric measures an additional quality of user experience. This article contributes to the development of effective spatial compression methods by utilizing the break of immersion as a benchmark for redirection techniques.

Kinematic dynamo, supersymmetry breaking, and chaos

NASA Astrophysics Data System (ADS)

Ovchinnikov, Igor V.; Enßlin, Torsten A.

2016-04-01

The kinematic dynamo (KD) describes the growth of magnetic fields generated by the flow of a conducting medium in the limit of vanishing backaction of the fields onto the flow. The KD is therefore an important model system for understanding astrophysical magnetism. Here, the mathematical correspondence between the KD and a specific stochastic differential equation (SDE) viewed from the perspective of the supersymmetric theory of stochastics (STS) is discussed. The STS is a novel, approximation-free framework to investigate SDEs. The correspondence reported here permits insights from the STS to be applied to the theory of KD and vice versa. It was previously known that the fast KD in the idealistic limit of no magnetic diffusion requires chaotic flows. The KD-STS correspondence shows that this is also true for the diffusive KD. From the STS perspective, the KD possesses a topological supersymmetry, and the dynamo effect can be viewed as its spontaneous breakdown. This supersymmetry breaking can be regarded as the stochastic generalization of the concept of dynamical chaos. As this supersymmetry breaking happens in both the diffusive and the nondiffusive cases, the necessity of the underlying SDE being chaotic is given in either case. The observed exponentially growing and oscillating KD modes prove physically that dynamical spectra of the STS evolution operator that break the topological supersymmetry exist with both real and complex ground state eigenvalues. Finally, we comment on the nonexistence of dynamos for scalar quantities.

The Potential for Restoration to Break the Grass/Fire Cycle in Dryland Ecosystems in Hawaii

DTIC Science & Technology

2016-11-01

Content of a Leaf PSAG Pleistocene Substrate Age Gradient PSW Pacific Southwest Station PTA Pohakuloa Training Area PV Photosynthetic Vegetation...resampled these images to 1.5 m resolution, and the study area encompassed 23 individual photographs. Due to variable solar illumination among...ecosystems many plant species benefit from similar conditions during regeneration, such as increased water availability, decreased solar radiation, and

Physical activity breaks and facilities in US secondary schools

PubMed Central

Hood, Nancy E.; Colabianchi, Natalie; Terry-McElrath, Yvonne M.; O’Malley, Patrick M.; Johnston, Lloyd D.

2014-01-01

BACKGROUND Research on physical activity breaks and facilities (indoor and outdoor) in secondary schools is relatively limited. METHODS School administrators and students in nationally representative samples of 8th (middle school) and 10th/12th grade (high school) students were surveyed annually from 2008-09 through 2011-12. School administrators reported information about physical activity breaks and facilities. Students self-reported height, weight, and physical activity. RESULTS The prevalence of physical activity breaks and indoor and outdoor facilities (dichotomized by median split) differed significantly by region of the country, school size, student race/ethnicity, and school socioeconomic status (SES). Breaks were associated with lower odds of overweight (adjusted odds ratio (AOR) = 0.91, 95% confidence interval (CI): 0.83-1.00) and obesity (AOR = 0.86, 95% CI: 0.75-0.99) among middle school students. Among low-SES middle school students and schools, higher indoor facilities were associated with lower rates of overweight and obesity. Among high school students, higher indoor and outdoor facilities were associated with 19%-42% higher odds of moderate-to-vigorous physical activity. CONCLUSIONS Physical activity breaks and school facilities may help to address high rates of overweight/obesity and low physical activity levels among secondary students, especially lower-SES students. Students in all schools should have equal access to these resources. PMID:25274169

Interrelation of soft and hard X-ray emissions during solar flares. I - Observations

NASA Technical Reports Server (NTRS)

Winglee, R. M.; Kiplinger, A. L.; Zarro, D. M.; Dulk, G. A.; Lemen, J. R.

1991-01-01

The interrelation between the acceleration and heating of electrons and ions during impulsive solar flares is determined on the basis of simulataneous observations of hard and soft X-ray emission from the Solar Maximum Mission at high time resolution (6 s). For all the flares, the hard X-rays are found to have a power-law spectrum which breaks down during the rise phase and beginning of the decay phase. After that, the spectrum changes to either a single power law or a power law that breaks up at high energies. The characteristics of the soft X-ray are found to depend on the flare position. It is suggested that small-scale quasi-static electric fields are important for determining the acceleration of the X-ray-producing electrons and the outflowing chromospheric ions.

Improved wavelength coded optical time domain reflectometry based on the optical switch.

PubMed

Zhu, Ninghua; Tong, Youwan; Chen, Wei; Wang, Sunlong; Sun, Wenhui; Liu, Jianguo

2014-06-16

This paper presents an improved wavelength coded time-domain reflectometry based on the 2 × 1 optical switch. In this scheme, in order to improve the signal-noise-ratio (SNR) of the beat signal, the improved system used an optical switch to obtain wavelength-stable, low-noise and narrow optical pulses for probe and reference. Experiments were set up to demonstrate a spatial resolution of 2.5m within a range of 70km and obtain the beat signal with line width narrower than 15 MHz within a range of 50 km in fiber break detection. A system for wavelength-division-multiplexing passive optical network (WDM-PON) monitoring was also constructed to detect the fiber break of different channels by tuning the current applied on the gating section of the distributed Bragg reflector (DBR) laser.

Finite element analysis of stress-breaking attachments on maxillary implant-retained overdentures.

PubMed

Tanino, Fuminori; Hayakawa, Iwao; Hirano, Shigezo; Minakuchi, Shunsuke

2007-01-01

The purpose of this study was to examine the effect of stress-breaking attachments at the connections between maxillary palateless overdentures and implants. Three-dimensional finite element models were used to reproduce an edentulous human maxilla with an implant-retained overdenture. Two-implant models (in the canine tooth positions on both sides) and four-implant models (in the canine and second premolar tooth positions on both sides) were examined. Stress-breaking material connecting the implants and denture was included around each abutment. Axial loads of 100 N were applied to the occlusal surface at the left first molar tooth positions. In each model, the influence of the stress-breaking attachments was compared by changing the elastic modulus from 1 to 3,000 MPa and the thickness of the stress-breaking material from 1 to 3 mm. Maximum stress at the implant-bone interface and stress at the cortical bone surface just under the loading point were calculated. In all models, maximum stress at the implant-bone interface with implants located in the canine tooth position was generated at the peri-implant bone on the loading side. As the elastic modulus of the stress-breaking materials increased, the stress increased at the implant-bone interface and decreased at the cortical bone surface. Moreover, stress at the implant-bone interface with 3-mm-thick stress-breaking material was smaller than that with 1-mm-thick material. Within the limitations of this experiment, stress generated at the implant-bone interface could be controlled by altering the elastic modulus and thickness of the stress-breaking materials.

High resolution spectroscopic study of Be Λ 10

DOE PAGES

Gogami, T.; Chen, C.; Kawama, D.; ...

2016-03-10

Spectroscopy of amore » $$^{10}_{\\Lambda}$$Be hypernucleus was carried out at JLab Hall C using the $$(e,e^{\\prime}K^{+})$$ reaction. A new magnetic spectrometer system (SPL+HES+HKS), specifically designed for high resolution hypernuclear spectroscopy, was used to obtain an energy spectrum with a resolution of 0.78 MeV (FWHM). The well-calibrated spectrometer system of the present experiment using the $$p(e,e^{\\prime}K^{+})\\Lambda,\\Sigma^{0}$$ reactions allowed us to determine the energy levels, and the binding energy of the ground state peak (mixture of 1$$^{-}$$ and 2$$^{-}$$ states) was obtained to be B$$_{\\Lambda}$$=8.55$$\\pm$$0.07(stat.)$$\\pm$$0.11(sys.) MeV. Furthermore, the result indicates that the ground state energy is shallower than that of an emulsion study by about 0.5 MeV which provides valuable experimental information on charge symmetry breaking effect in the $$\\Lambda N$$ interaction.« less

Multiscale 3D virtual dissections of 100-million-year-old flowers using X-ray synchrotron micro- and nanotomography.

PubMed

Moreau, Jean-David; Cloetens, Peter; Gomez, Bernard; Daviero-Gomez, Véronique; Néraudeau, Didier; Lafford, Tamzin A; Tafforeau, Paul

2014-02-01

A multiscale approach combining phase-contrast X-ray micro- and nanotomography is applied for imaging a Cretaceous fossil inflorescence in the resolution range from 0.75 μm to 50 nm. The wide range of scale views provides three-dimensional reconstructions from the external gross morphology of the inflorescence fragment to the finest exine sculptures of in situ pollen. This approach enables most of the characteristics usually observed under light microscopy, or with low magnification under scanning and transmission electron microscopy, to be obtained nondestructively. In contrast to previous tomography studies of fossil and extant flowers that used resolutions down to the micron range, we used voxels with a 50 nm side in local tomography scans. This high level of resolution enables systematic affinities of fossil flowers to be established without breaking or slicing specimens.

Crystallization of a fungal lytic polysaccharide monooxygenase expressed from glycoengineered Pichia pastoris for X-ray and neutron diffraction

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

O'Dell, William B.; Swartz, Paul D.; Weiss, Kevin L.

Lytic polysaccharide monooxygenases (LPMOs) are carbohydrate-disrupting enzymes secreted by bacteria and fungi that break glycosidic bondsviaan oxidative mechanism. Fungal LPMOs typically act on cellulose and can enhance the efficiency of cellulose-hydrolyzing enzymes that release soluble sugars for bioethanol production or other industrial uses. The enzyme PMO-2 fromNeurospora crassa(NcPMO-2) was heterologously expressed inPichia pastoristo facilitate crystallographic studies of the fungal LPMO mechanism. Diffraction resolution and crystal morphology were improved by expressingNcPMO-2 from a glycoengineered strain ofP. pastorisand by the use of crystal seeding methods, respectively. These improvements resulted in high-resolution (1.20 Å) X-ray diffraction data collection at 100 K and themore » production of a largeNcPMO-2 crystal suitable for room-temperature neutron diffraction data collection to 2.12 Å resolution.« less

High resolution spectroscopic study of Be10Lambda;

NASA Astrophysics Data System (ADS)

Gogami, T.; Chen, C.; Kawama, D.; Achenbach, P.; Ahmidouch, A.; Albayrak, I.; Androic, D.; Asaturyan, A.; Asaturyan, R.; Ates, O.; Baturin, P.; Badui, R.; Boeglin, W.; Bono, J.; Brash, E.; Carter, P.; Chiba, A.; Christy, E.; Danagoulian, S.; de Leo, R.; Doi, D.; Elaasar, M.; Ent, R.; Fujii, Y.; Fujita, M.; Furic, M.; Gabrielyan, M.; Gan, L.; Garibaldi, F.; Gaskell, D.; Gasparian, A.; Han, Y.; Hashimoto, O.; Horn, T.; Hu, B.; Hungerford, Ed. V.; Jones, M.; Kanda, H.; Kaneta, M.; Kato, S.; Kawai, M.; Khanal, H.; Kohl, M.; Liyanage, A.; Luo, W.; Maeda, K.; Margaryan, A.; Markowitz, P.; Maruta, T.; Matsumura, A.; Maxwell, V.; Mkrtchyan, A.; Mkrtchyan, H.; Nagao, S.; Nakamura, S. N.; Narayan, A.; Neville, C.; Niculescu, G.; Niculescu, M. I.; Nunez, A.; Nuruzzaman, Okayasu, Y.; Petkovic, T.; Pochodzalla, J.; Qiu, X.; Reinhold, J.; Rodriguez, V. M.; Samanta, C.; Sawatzky, B.; Seva, T.; Shichijo, A.; Tadevosyan, V.; Tang, L.; Taniya, N.; Tsukada, K.; Veilleux, M.; Vulcan, W.; Wesselmann, F. R.; Wood, S. A.; Yamamoto, T.; Ya, L.; Ye, Z.; Yokota, K.; Yuan, L.; Zhamkochyan, S.; Zhu, L.; Hksjlab E05-115 Collaboration

2016-03-01

Spectroscopy of a Be10Lambda; hypernucleus was carried out at JLab Hall C using the (e ,e'K+) reaction. A new magnetic spectrometer system (SPL+HES+HKS), specifically designed for high resolution hypernuclear spectroscopy, was used to obtain an energy spectrum with a resolution of ˜0.78 MeV (FWHM). The well-calibrated spectrometer system of the present experiment using p (e ,e'K+)Λ ,Σ0 reactions allowed us to determine the energy levels; and the binding energy of the ground-state peak (mixture of 1- and 2- states) was found to be BΛ=8.55 ±0.07 (stat . ) ±0.11 (sys . ) MeV. The result indicates that the ground-state energy is shallower than that of an emulsion study by about 0.5 MeV which provides valuable experimental information on the charge symmetry breaking effect in the Λ N interaction.

Understanding Breaks in Flare X-Ray Spectra: Evaluation of a Cospatial Collisional Return-current Model

NASA Astrophysics Data System (ADS)

Alaoui, Meriem; Holman, Gordon D.

2017-12-01

Hard X-ray (HXR) spectral breaks are explained in terms of a one-dimensional model with a cospatial return current. We study 19 flares observed by the Ramaty High Energy Solar Spectroscopic Imager with strong spectral breaks at energies around a few deka-keV, which cannot be explained by isotropic albedo or non-uniform ionization alone. We identify these breaks at the HXR peak time, but we obtain 8 s cadence spectra of the entire impulsive phase. Electrons with an initially power-law distribution and a sharp low-energy cutoff lose energy through return-current losses until they reach the thick target, where they lose their remaining energy through collisions. Our main results are as follows. (1) The return-current collisional thick-target model provides acceptable fits for spectra with strong breaks. (2) Limits on the plasma resistivity are derived from the fitted potential drop and deduced electron-beam flux density, assuming the return current is a drift current in the ambient plasma. These resistivities are typically 2–3 orders of magnitude higher than the Spitzer resistivity at the fitted temperature, and provide a test for the adequacy of classical resistivity and the stability of the return current. (3) Using the upper limit of the low-energy cutoff, the return current is always stable to the generation of ion-acoustic and electrostatic ion-cyclotron instabilities when the electron temperature is nine times lower than the ion temperature. (4) In most cases, the return current is most likely primarily carried by runaway electrons from the tail of the thermal distribution rather than by the bulk drifting thermal electrons. For these cases, anomalous resistivity is not required.

Optimised detection of mitochondrial DNA strand breaks.

PubMed

Hanna, Rebecca; Crowther, Jonathan M; Bulsara, Pallav A; Wang, Xuying; Moore, David J; Birch-Machin, Mark A

2018-05-04

Intrinsic and extrinsic factors that induce cellular oxidative stress damage tissue integrity and promote ageing, resulting in accumulative strand breaks to the mitochondrial DNA (mtDNA) genome. Limited repair mechanisms and close proximity to superoxide generation make mtDNA a prominent biomarker of oxidative damage. Using human DNA we describe an optimised long-range qPCR methodology that sensitively detects mtDNA strand breaks relative to a suite of short mitochondrial and nuclear DNA housekeeping amplicons, which control for any variation in mtDNA copy number. An application is demonstrated by detecting 16-36-fold mtDNA damage in human skin cells induced by hydrogen peroxide and solar simulated radiation. Copyright © 2018 Elsevier B.V. and Mitochondria Research Society. All rights reserved.

Connecting with the Big Picture

ERIC Educational Resources Information Center

Brophy, Jere

2009-01-01

This article concludes the special issue on identity and motivation by discussing the five preceding contributions. It identifies strengths and limitations in each article and places them within a larger context, indicating ways that the authors could broaden the scope of their inquiries by breaking free of existing limitations or adding…

Fast resolution change in neutral helium atom microscopy

NASA Astrophysics Data System (ADS)

Flatabø, R.; Eder, S. D.; Ravn, A. K.; Samelin, B.; Greve, M. M.; Reisinger, T.; Holst, B.

2018-05-01

In neutral helium atom microscopy, a beam of atoms is scanned across a surface. Though still in its infancy, neutral helium microscopy has seen a rapid development over the last few years. The inertness and low energy of the helium atoms (less than 0.1 eV) combined with a very large depth of field and the fact that the helium atoms do not penetrate any solid material at low energies open the possibility for a non-destructive instrument that can measure topology on the nanoscale even on fragile and insulating surfaces. The resolution is determined by the beam spot size on the sample. Fast resolution change is an attractive property of a microscope because it allows different aspects of a sample to be investigated and makes it easier to identify specific features. However up till now it has not been possible to change the resolution of a helium microscope without breaking the vacuum and changing parts of the atom source. Here we present a modified source design, which allows fast, step wise resolution change. The basic design idea is to insert a moveable holder with a series of collimating apertures in front of the source, thus changing the effective source size of the beam and thereby the spot size on the surface and thus the microscope resolution. We demonstrate a design with 3 resolution steps. The number of resolution steps can easily be extended.

Investigating the impact of surface wave breaking on modeling the trajectories of drifters in the northern Adriatic Sea during a wind-storm event

USGS Publications Warehouse

Carniel, S.; Warner, J.C.; Chiggiato, J.; Sclavo, M.

2009-01-01

An accurate numerical prediction of the oceanic upper layer velocity is a demanding requirement for many applications at sea and is a function of several near-surface processes that need to be incorporated in a numerical model. Among them, we assess the effects of vertical resolution, different vertical mixing parameterization (the so-called Generic Length Scale -GLS- set of k-??, k-??, gen, and the Mellor-Yamada), and surface roughness values on turbulent kinetic energy (k) injection from breaking waves. First, we modified the GLS turbulence closure formulation in the Regional Ocean Modeling System (ROMS) to incorporate the surface flux of turbulent kinetic energy due to wave breaking. Then, we applied the model to idealized test cases, exploring the sensitivity to the above mentioned factors. Last, the model was applied to a realistic situation in the Adriatic Sea driven by numerical meteorological forcings and river discharges. In this case, numerical drifters were released during an intense episode of Bora winds that occurred in mid-February 2003, and their trajectories compared to the displacement of satellite-tracked drifters deployed during the ADRIA02-03 sea-truth campaign. Results indicted that the inclusion of the wave breaking process helps improve the accuracy of the numerical simulations, subject to an increase in the typical value of the surface roughness z0. Specifically, the best performance was obtained using ??CH = 56,000 in the Charnok formula, the wave breaking parameterization activated, k-?? as the turbulence closure model. With these options, the relative error with respect to the average distance of the drifter was about 25% (5.5 km/day). The most sensitive factors in the model were found to be the value of ??CH enhanced with respect to a standard value, followed by the adoption of wave breaking parameterization and the particular turbulence closure model selected. ?? 2009 Elsevier Ltd.

Fundamental limits of reconstruction-based superresolution algorithms under local translation.

PubMed

Lin, Zhouchen; Shum, Heung-Yeung

2004-01-01

Superresolution is a technique that can produce images of a higher resolution than that of the originally captured ones. Nevertheless, improvement in resolution using such a technique is very limited in practice. This makes it significant to study the problem: "Do fundamental limits exist for superresolution?" In this paper, we focus on a major class of superresolution algorithms, called the reconstruction-based algorithms, which compute high-resolution images by simulating the image formation process. Assuming local translation among low-resolution images, this paper is the first attempt to determine the explicit limits of reconstruction-based algorithms, under both real and synthetic conditions. Based on the perturbation theory of linear systems, we obtain the superresolution limits from the conditioning analysis of the coefficient matrix. Moreover, we determine the number of low-resolution images that are sufficient to achieve the limit. Both real and synthetic experiments are carried out to verify our analysis.

Can phenological models predict tree phenology accurately in the future? The unrevealed hurdle of endodormancy break.

PubMed

Chuine, Isabelle; Bonhomme, Marc; Legave, Jean-Michel; García de Cortázar-Atauri, Iñaki; Charrier, Guillaume; Lacointe, André; Améglio, Thierry

2016-10-01

The onset of the growing season of trees has been earlier by 2.3 days per decade during the last 40 years in temperate Europe because of global warming. The effect of temperature on plant phenology is, however, not linear because temperature has a dual effect on bud development. On one hand, low temperatures are necessary to break bud endodormancy, and, on the other hand, higher temperatures are necessary to promote bud cell growth afterward. Different process-based models have been developed in the last decades to predict the date of budbreak of woody species. They predict that global warming should delay or compromise endodormancy break at the species equatorward range limits leading to a delay or even impossibility to flower or set new leaves. These models are classically parameterized with flowering or budbreak dates only, with no information on the endodormancy break date because this information is very scarce. Here, we evaluated the efficiency of a set of phenological models to accurately predict the endodormancy break dates of three fruit trees. Our results show that models calibrated solely with budbreak dates usually do not accurately predict the endodormancy break date. Providing endodormancy break date for the model parameterization results in much more accurate prediction of this latter, with, however, a higher error than that on budbreak dates. Most importantly, we show that models not calibrated with endodormancy break dates can generate large discrepancies in forecasted budbreak dates when using climate scenarios as compared to models calibrated with endodormancy break dates. This discrepancy increases with mean annual temperature and is therefore the strongest after 2050 in the southernmost regions. Our results claim for the urgent need of massive measurements of endodormancy break dates in forest and fruit trees to yield more robust projections of phenological changes in a near future. © 2016 John Wiley & Sons Ltd.

Advanced ADA Workshop Held in Biloxi, Mississippi on 24-27 January 1989

DTIC Science & Technology

1989-01-27

Software Engineering (Break at 2:30j 6:30-8:00 Keesler AFB Reception Officers’ Club WEDNESDAY - 25 JANIJ1APY 9:00-12:00 Bldc 1002 Generics (Break at 10...TextIO.FileType: -- NO! procedure Wrong; -- problem is FileType is limited private Object Parameters A More Useful Example generic Control -Block : in out... control the precision used Float Type Parameters An Example generic type FloatType is digits <>; function Sqrt(X : FloatType) return FloatType

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

Arnowitt, R.; Nath, P.

A survey is given of supersymmetry and supergravity and their phenomenology. Some of the topics discussed are the basic ideas of global supersymmetry, the minimal supersymmetric Standard Model (MSSM) and its phenomenology, the basic ideas of local supersymmetry (supergravity), grand unification, supersymmetry breaking in supergravity grand unified models, radiative breaking of SU(2) {times} U(1), proton decay, cosmological constraints, and predictions of supergravity grand unified models. While the number of detailed derivations are necessarily limited, a sufficient number of results are given so that a reader can get a working knowledge of this field.

Paediatric SpRs' experiences of breaking bad news.

PubMed

Horwitz, N; Ellis, J

2007-09-01

To ascertain the level of support and training available to paediatric specialist registrars (SpRs) in breaking bad news and their self-reported confidence in this task. A questionnaire-based survey. Paediatric SpRs working in North Thames region. Specialist registrars (n = 206) were sent a questionnaire relating to the level of support and training available to them in breaking bad news and their attitudes to this task. A repeat questionnaire was sent out 2 weeks later. The response rate was 54.9%. The study sample included 78 females and 34 males. The median year of qualification was 1995 [interquartile range (IQR) 1993-1997] and the median year of Calman training was Year 3 (IQR 2-4). Only 15.9% of participants had guidelines where they worked and 91.2% had received training in breaking bad news. Median self-perceived confidence in breaking bad news was rated as 4 out of 5. Only 21.2% of all respondents had both disclosed a diagnosis of Down syndrome and received feedback on their performance from their seniors. Few SpRs were able to adhere to all evidence-based recommendations for breaking bad news. Most SpRs had received training in breaking bad news and self-reported confidence in this skill was high, although their hands-on experience was limited. Recent research shows, however, that parental dissatisfaction with the way in which bad news is broken remains high. The potential discrepancy between self-reported confidence and actual competence casts doubt on the value of self-evaluation.

Simulation of breaking waves using the high-order spectral method with laboratory experiments: wave-breaking energy dissipation

NASA Astrophysics Data System (ADS)

Seiffert, Betsy R.; Ducrozet, Guillaume

2018-01-01

We examine the implementation of a wave-breaking mechanism into a nonlinear potential flow solver. The success of the mechanism will be studied by implementing it into the numerical model HOS-NWT, which is a computationally efficient, open source code that solves for the free surface in a numerical wave tank using the high-order spectral (HOS) method. Once the breaking mechanism is validated, it can be implemented into other nonlinear potential flow models. To solve for wave-breaking, first a wave-breaking onset parameter is identified, and then a method for computing wave-breaking associated energy loss is determined. Wave-breaking onset is calculated using a breaking criteria introduced by Barthelemy et al. (J Fluid Mech https://arxiv.org/pdf/1508.06002.pdf, submitted) and validated with the experiments of Saket et al. (J Fluid Mech 811:642-658, 2017). Wave-breaking energy dissipation is calculated by adding a viscous diffusion term computed using an eddy viscosity parameter introduced by Tian et al. (Phys Fluids 20(6): 066,604, 2008, Phys Fluids 24(3), 2012), which is estimated based on the pre-breaking wave geometry. A set of two-dimensional experiments is conducted to validate the implemented wave breaking mechanism at a large scale. Breaking waves are generated by using traditional methods of evolution of focused waves and modulational instability, as well as irregular breaking waves with a range of primary frequencies, providing a wide range of breaking conditions to validate the solver. Furthermore, adjustments are made to the method of application and coefficient of the viscous diffusion term with negligible difference, supporting the robustness of the eddy viscosity parameter. The model is able to accurately predict surface elevation and corresponding frequency/amplitude spectrum, as well as energy dissipation when compared with the experimental measurements. This suggests the model is capable of calculating wave-breaking onset and energy dissipation successfully for a wide range of breaking conditions. The model is also able to successfully calculate the transfer of energy between frequencies due to wave focusing and wave breaking. This study is limited to unidirectional waves but provides a valuable basis for future application of the wave-breaking model to a multidirectional wave field. By including parameters for removing energy due to wave-breaking into a nonlinear potential flow solver, the risk of developing numerical instabilities due to an overturning wave is decreased, thereby increasing the application range of the model, including calculating more extreme sea states. A computationally efficient and accurate model for the generation of a nonlinear random wave field is useful for predicting the dynamic response of offshore vessels and marine renewable energy devices, predicting loads on marine structures, and in the study of open ocean wave generation and propagation in a realistic environment.

Intraoperative optical coherence tomography assisted analysis of pars Plana vitrectomy for retinal detachment in morning glory syndrome: a case report.

PubMed

Lytvynchuk, Lyubomyr M; Glittenberg, Carl G; Ansari-Shahrezaei, Siamak; Binder, Susanne

2017-08-01

The pathogenesis of non-rhegmatogenous retinal detachment (non-RRD) associated with morning glory syndrome (MGS) is not established, as well as best surgical approach to treat RD. Our purpose was to analyse intraoperative optical coherence tomography data (iOCT) in all steps of pars plana vitrectomy (PPV) for non-RRD in MGS, in order to follow pathophysiological aspects of the disease and to understand the tissues behaviour during surgical workflow. Intraoperative spectral domain optical coherent tomography (iSD-OCT) assisted PPV using Rescan 700 (Carl Zeiss Meditech, Jena, Germany) with epiretinal membrane (ERM) and internal retinal membrane (ILM) peeling, and air endotamponade was performed on the only eye of a 21 years old female with non-RRD associated with MGS. BCVA, pre-, intra- and postoperative OCT were performed along with standard ocular examination. iOCT video and snapshots were analysed intra- and postoperatively using post-processing approach using graphic software. The progression of non-RRD resulted in best corrected visual acuity (BCVA) decrease from 0.8 to 0.2. Triamcinolone enhanced iOCT imaging revealed strong vitreous traction and adhesion above the macula and optic disc. Internal limiting membrane was peeled under iOCT control to prevent the peeling of inner layers of the retinal schisis. No retinal break was detected, and only air endotamponade was performed. The retina reattached during first 4 weeks of follow-up with gradual resolution of intraretinal- and subretinal fluid, and remained stable in 12 months. BCVA improved to 0.8. Based on iSD-OCT findings we assume that non-RRD in this case of MGS is caused primarily by the vitreous traction with further possible formation of the retinal breaks. Retinal reattachment reached only with air endotamponade strongly advocates the tractional component of non-RRD and retinal schisis assotiated with MGS. Early PPV for central non-RRD and retinal schisis with the use of iOCT can be performed in more safe and controlled manner and has to be considered to reduce the risk of retinal break formation and to prevent the central vision loss.

Direct detection of a break in the teraelectronvolt cosmic-ray spectrum of electrons and positrons

NASA Astrophysics Data System (ADS)

DAMPE Collaboration; Ambrosi, G.; An, Q.; Asfandiyarov, R.; Azzarello, P.; Bernardini, P.; Bertucci, B.; Cai, M. S.; Chang, J.; Chen, D. Y.; Chen, H. F.; Chen, J. L.; Chen, W.; Cui, M. Y.; Cui, T. S.; D'Amone, A.; de Benedittis, A.; De Mitri, I.; di Santo, M.; Dong, J. N.; Dong, T. K.; Dong, Y. F.; Dong, Z. X.; Donvito, G.; Droz, D.; Duan, K. K.; Duan, J. L.; Duranti, M.; D'Urso, D.; Fan, R. R.; Fan, Y. Z.; Fang, F.; Feng, C. Q.; Feng, L.; Fusco, P.; Gallo, V.; Gan, F. J.; Gao, M.; Gao, S. S.; Gargano, F.; Garrappa, S.; Gong, K.; Gong, Y. Z.; Guo, D. Y.; Guo, J. H.; Hu, Y. M.; Huang, G. S.; Huang, Y. Y.; Ionica, M.; Jiang, D.; Jiang, W.; Jin, X.; Kong, J.; Lei, S. J.; Li, S.; Li, X.; Li, W. L.; Li, Y.; Liang, Y. F.; Liang, Y. M.; Liao, N. H.; Liu, H.; Liu, J.; Liu, S. B.; Liu, W. Q.; Liu, Y.; Loparco, F.; Ma, M.; Ma, P. X.; Ma, S. Y.; Ma, T.; Ma, X. Q.; Ma, X. Y.; Marsella, G.; Mazziotta, M. N.; Mo, D.; Niu, X. Y.; Peng, X. Y.; Peng, W. X.; Qiao, R.; Rao, J. N.; Salinas, M. M.; Shang, G. Z.; H. Shen, W.; Shen, Z. Q.; Shen, Z. T.; Song, J. X.; Su, H.; Su, M.; Sun, Z. Y.; Surdo, A.; Teng, X. J.; Tian, X. B.; Tykhonov, A.; Vagelli, V.; Vitillo, S.; Wang, C.; Wang, H.; Wang, H. Y.; Wang, J. Z.; Wang, L. G.; Wang, Q.; Wang, S.; Wang, X. H.; Wang, X. L.; Wang, Y. F.; Wang, Y. P.; Wang, Y. Z.; Wen, S. C.; Wang, Z. M.; Wei, D. M.; Wei, J. J.; Wei, Y. F.; Wu, D.; Wu, J.; Wu, L. B.; Wu, S. S.; Wu, X.; Xi, K.; Xia, Z. Q.; Xin, Y. L.; Xu, H. T.; Xu, Z. L.; Xu, Z. Z.; Xue, G. F.; Yang, H. B.; Yang, P.; Yang, Y. Q.; Yang, Z. L.; Yao, H. J.; Yu, Y. H.; Yuan, Q.; Yue, C.; Zang, J. J.; Zhang, C.; Zhang, D. L.; Zhang, F.; Zhang, J. B.; Zhang, J. Y.; Zhang, J. Z.; Zhang, L.; Zhang, P. F.; Zhang, S. X.; Zhang, W. Z.; Zhang, Y.; Zhang, Y. J.; Zhang, Y. Q.; Zhang, Y. L.; Zhang, Y. P.; Zhang, Z.; Zhang, Z. Y.; Zhao, H.; Zhao, H. Y.; Zhao, X. F.; Zhou, C. Y.; Zhou, Y.; Zhu, X.; Zhu, Y.; Zimmer, S.

2017-12-01

High-energy cosmic-ray electrons and positrons (CREs), which lose energy quickly during their propagation, provide a probe of Galactic high-energy processes and may enable the observation of phenomena such as dark-matter particle annihilation or decay. The CRE spectrum has been measured directly up to approximately 2 teraelectronvolts in previous balloon- or space-borne experiments, and indirectly up to approximately 5 teraelectronvolts using ground-based Cherenkov γ-ray telescope arrays. Evidence for a spectral break in the teraelectronvolt energy range has been provided by indirect measurements, although the results were qualified by sizeable systematic uncertainties. Here we report a direct measurement of CREs in the energy range 25 gigaelectronvolts to 4.6 teraelectronvolts by the Dark Matter Particle Explorer (DAMPE) with unprecedentedly high energy resolution and low background. The largest part of the spectrum can be well fitted by a ‘smoothly broken power-law’ model rather than a single power-law model. The direct detection of a spectral break at about 0.9 teraelectronvolts confirms the evidence found by previous indirect measurements, clarifies the behaviour of the CRE spectrum at energies above 1 teraelectronvolt and sheds light on the physical origin of the sub-teraelectronvolt CREs.

Large-Scale Direct-Writing of Aligned Nanofibers for Flexible Electronics.

PubMed

Ye, Dong; Ding, Yajiang; Duan, Yongqing; Su, Jiangtao; Yin, Zhouping; Huang, Yong An

2018-05-01

Nanofibers/nanowires usually exhibit exceptionally low flexural rigidities and remarkable tolerance against mechanical bending, showing superior advantages in flexible electronics applications. Electrospinning is regarded as a powerful process for this 1D nanostructure; however, it can only be able to produce chaotic fibers that are incompatible with the well-patterned microstructures in flexible electronics. Electro-hydrodynamic (EHD) direct-writing technology enables large-scale deposition of highly aligned nanofibers in an additive, noncontact, real-time adjustment, and individual control manner on rigid or flexible, planar or curved substrates, making it rather attractive in the fabrication of flexible electronics. In this Review, the ground-breaking research progress in the field of EHD direct-writing technology is summarized, including a brief chronology of EHD direct-writing techniques, basic principles and alignment strategies, and applications in flexible electronics. Finally, future prospects are suggested to advance flexible electronics based on orderly arranged EHD direct-written fibers. This technology overcomes the limitations of the resolution of fabrication and viscosity of ink of conventional inkjet printing, and represents major advances in manufacturing of flexible electronics. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Novel Low-Temperature Poss-Containing Siloxane Elastomers

NASA Technical Reports Server (NTRS)

Belcher, Marcus A.; Hinkley, Jeffrey A.; Kiri, Neha N.; Lillehei, Peter T.

2008-01-01

One route to increased aircraft performance is through the use of flexible, shape-changeable aerodynamics effectors. However, state of the art materials are not flexible or durable enough over the required broad temperature range. Mixed siloxanes were crosslinked by polyhedral oligomeric silsesquioxanes (POSS) producing novel materials that remained flexible and elastic from -55 to 94 C. POSS molecules were chemically modified to generate homogeneous distributions within the siloxane matrix. High resolution scanning electron microscope (HRSEM) images indicated homogenous POSS distribution up to 0.8 wt %. Above the solubility limit, POSS aggregates could be seen both macroscopically and via SEM (approx.60-120 nm). Tensile tests were performed to determine Young s modulus, tensile strength, and elongation at break over the range of temperatures associated with transonic aircraft use (-55 to 94 C; -65 to 200 F). The siloxane materials developed here maintained flexibility at -55 C, where previous candidate materials failed. At room temperature, films could be elongated up to 250 % before rupturing. At -55 and 94 C, however, films could be elongated up to 400 % and 125 %, respectively.

Comparison of in situ microstructure measurements to different turbulence closure schemes in a 3-D numerical ocean circulation model

NASA Astrophysics Data System (ADS)

Costa, Andrea; Doglioli, Andrea M.; Marsaleix, Patrick; Petrenko, Anne A.

2017-12-01

In situ measurements of kinetic energy dissipation rate ε and estimates of eddy viscosity KZ from the Gulf of Lion (NW Mediterranean Sea) are used to assess the ability of k - ɛ and k - ℓ closure schemes to predict microscale turbulence in a 3-D numerical ocean circulation model. Two different surface boundary conditions are considered in order to investigate their influence on each closure schemes' performance. The effect of two types of stability functions and optical schemes on the k - ɛ scheme is also explored. Overall, the 3-D model predictions are much closer to the in situ data in the surface mixed layer as opposed to below it. Above the mixed layer depth, we identify one model's configuration that outperforms all the other ones. Such a configuration employs a k - ɛ scheme with Canuto A stability functions, surface boundary conditions parameterizing wave breaking and an appropriate photosynthetically available radiation attenuation length. Below the mixed layer depth, reliability is limited by the model's resolution and the specification of a hard threshold on the minimum turbulent kinetic energy.

Enzyme-adenylate structure of a bacterial ATP-dependent DNA ligase with a minimized DNA-binding surface.

PubMed

Williamson, Adele; Rothweiler, Ulli; Leiros, Hanna Kirsti Schrøder

2014-11-01

DNA ligases are a structurally diverse class of enzymes which share a common catalytic core and seal breaks in the phosphodiester backbone of double-stranded DNA via an adenylated intermediate. Here, the structure and activity of a recombinantly produced ATP-dependent DNA ligase from the bacterium Psychromonas sp. strain SP041 is described. This minimal-type ligase, like its close homologues, is able to ligate singly nicked double-stranded DNA with high efficiency and to join cohesive-ended and blunt-ended substrates to a more limited extent. The 1.65 Å resolution crystal structure of the enzyme-adenylate complex reveals no unstructured loops or segments, and suggests that this enzyme binds the DNA without requiring full encirclement of the DNA duplex. This is in contrast to previously characterized minimal DNA ligases from viruses, which use flexible loop regions for DNA interaction. The Psychromonas sp. enzyme is the first structure available for the minimal type of bacterial DNA ligases and is the smallest DNA ligase to be crystallized to date.

Discovery of Enhanced Magnetoelectric Coupling through Electric Field Control of Two-Magnon Scattering within Distorted Nanostructures.

PubMed

Xue, Xu; Zhou, Ziyao; Dong, Guohua; Feng, Mengmeng; Zhang, Yijun; Zhao, Shishun; Hu, Zhongqiang; Ren, Wei; Ye, Zuo-Guang; Liu, Yaohua; Liu, Ming

2017-09-26

Electric field control of dynamic spin interactions is promising to break through the limitation of the magnetostatic interaction based magnetoelectric (ME) effect. In this work, electric field control of the two-magnon scattering (TMS) effect excited by in-plane lattice rotation has been demonstrated in a La 0.7 Sr 0.3 MnO 3 (LSMO)/Pb(Mn 2/3 Nb 1/3 )-PbTiO 3 (PMN-PT) (011) multiferroic heterostructure. Compared with the conventional strain-mediated ME effect, a giant enhancement of ME effect up to 950% at the TMS critical angle is precisely determined by angular resolution of the ferromagnetic resonance (FMR) measurement. Particularly, a large electric field modulation of magnetic anisotropy (464 Oe) and FMR line width (401 Oe) is achieved at 173 K. The electric-field-controllable TMS effect and its correlated ME effect have been explained by electric field modulation of the planar spin interactions triggered by spin-lattice coupling. The enhancement of the ME effect at various temperatures and spin dynamics control are promising paradigms for next-generation voltage-tunable spintronic devices.

Analysis of velocity and magnetic field fluctuations from simulated Solar Probe Plus measurements: Interpretation and predictions.

NASA Astrophysics Data System (ADS)

Perez, J. C.; Chandran, B. D. G.

2016-12-01

As Solar Probe Plus (SPP) explores the near-Sun environment, our ability to obtain meaningful interpretation of in-situ measurements faces two significant challenges. The first challenge is that the Taylor Hypothesis (TH), which is normally used in the interpretation of existing spacecraft data, breaks down at the low heliocentric distances that SPP mission will explore. The second challenge is our limited understanding of turbulence in this region, largely due to the theoretical and numerical difficulties in modeling this problem. In this work we present recent progress towards overcoming these challenges using high-resolution numerical simulations of Alfvenic turbulence in the inner heliosphere. We fly virtual SPP spacecraft in the simulation domain to obtain single-point measurements of the velocity and magnetic field fluctuations at several radial locations relevant to SPP. We use these virtual measurements to 1) validate a recently introduced modified TH that allows one to recover the spatial structure of the dominant (outward-propagating) Alfvenic fluctuations, of the kind SPP will encounter; and 2) to compare these virtual observations with our most recent phenomenological models of reflection-driven Alfven turbulence.

Radon

MedlinePlus

... Home or Building? Radon forms naturally. Uranium in soil or rock breaks down to form radium, which ... lung cancer. Because radon comes from rock and soil, it can be found anywhere. Exposure to limited ...

The Art of Photoelectron Spectroscopy, from Micro to Nano

NASA Astrophysics Data System (ADS)

Rotenberg, Eli

Angle-resolved photoemission spectroscopy (ARPES) was developed for the determination of the electronic bandstructure of solids. In the last 20 years, ARPES has become nearly unlimited with respect to instrumental resolution, and therefore able to illuminate more subtle electronic aspects, such as ground-state symmetry breaking and the many-body interactions (MBIs) that characterize ground states such as superconductivity. These MBIs involve exchange of momentum among electrons or with excitations such as phonons, and can therefore couple to nanoscale structures. By controlling the structure at the nanoscale, we can therefore hope to control or enhance the ground state properties of materials through nanoscale engineering. This dream has motivated the development of nanoscale ARPES (nanoARPES) machines that are now coming online worldwide. After a brief overview, I will show the latest results from the new nanoARPES endstation at the MAESTRO facility (Microscopic and Electronic Structure Observatory), a new user beamline commissioned this year at the Advanced Light Source (ALS). We achieved routine operation at spatial resolution around 120 nm, and expect improvement down to 50 nm or better. Examples will include graphene and 2D-metal-chalcogenide heterostructures. I will also discuss the prospects for dramatic improvements expected as new diffraction-limited light sources such as the ALS-U project are realized. Work performed at the Advanced Light Source is supported by the Director, Office of Science, Office of Basic Energy Sciences, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.

Breaking bad news: A communication competency for ophthalmology training programs.

PubMed

Hilkert, Sarah M; Cebulla, Colleen M; Jain, Shelly Gupta; Pfeil, Sheryl A; Benes, Susan C; Robbins, Shira L

As the ophthalmology accreditation system undergoes major changes, training programs must evaluate residents in the 6 core competencies, including appropriately communicating bad news. Although the literature is replete with recommendations for breaking bad news across various non-ophthalmology specialties, no formal training programs exist for ophthalmology. There are many valuable lessons to be learned from our colleagues regarding this important skill. We examine the historic basis for breaking bad news, explore current recommendations among other specialties, and then evaluate a pilot study in breaking bad news for ophthalmology residents. The results of this study are limited by a small number of residents at a single academic center. Future studies from multiple training programs should be conducted to further evaluate the need and efficacy of formal communication skills training in this area, as well as the generalizability of our pilot training program. If validated, this work could serve as a template for future ophthalmology resident training and evaluation in this core competency. Copyright © 2016 Elsevier Inc. All rights reserved.

Breaking bad news: a communication competency for ophthalmology training programs

PubMed Central

Hilkert, Sarah M.; Cebulla, Colleen M.; Jain, Shelly Gupta; Pfeil, Sheryl A.; Benes, Susan C.; Robbins, Shira L.

2016-01-01

As the ophthalmology accreditation system undergoes major changes, training programs must evaluate residents in the 6 core competencies, including appropriately communicating bad news. Although the literature is replete with recommendations for breaking bad news across various non-ophthalmology specialties, no formal training programs exist for ophthalmology. There are many valuable lessons to be learned from our non-ophthalmology colleagues regarding this important skill. We examine the historic basis for breaking bad news, explores current recommendations among other specialties, and then evaluate a pilot study to teach breaking bad news to ophthalmology residents. The results of this study are limited by a small number of residents at a single academic center. Future studies from multiple training programs should be conducted to further evaluate the need and efficacy of formal communication skills training in this area, as well as the generalizability of our pilot training program. If validated, this work could serve as a template for future ophthalmology resident training and evaluation in this core competency. PMID:27134009

Symmetry associated with symmetry break: Revisiting ants and humans escaping from multiple-exit rooms

NASA Astrophysics Data System (ADS)

Ji, Q.; Xin, C.; Tang, S. X.; Huang, J. P.

2018-02-01

Crowd panic has incurred massive injuries or deaths throughout the world, and thus understanding it is particularly important. It is now a common knowledge that crowd panic induces "symmetry break" in which some exits are jammed while others are underutilized. Amazingly, here we show, by experiment, simulation and theory, that a class of symmetry patterns come to appear for ants and humans escaping from multiple-exit rooms while the symmetry break exists. Our symmetry pattern is described by the fact that the ratio between the ensemble-averaging numbers of ants or humans escaping from different exits is equal to the ratio between the widths of the exits. The mechanism lies in the effect of heterogeneous preferences of agents with limited information for achieving the Nash equilibrium. This work offers new insights into how to improve public safety because large public areas are always equipped with multiple exits, and it also brings an ensemble-averaging method for seeking symmetry associated with symmetry breaking.

Faunal breaks and species composition of Indo-Pacific corals: the role of plate tectonics, environment and habitat distribution.

PubMed

Keith, S A; Baird, A H; Hughes, T P; Madin, J S; Connolly, S R

2013-07-22

Species richness gradients are ubiquitous in nature, but the mechanisms that generate and maintain these patterns at macroecological scales remain unresolved. We use a new approach that focuses on overlapping geographical ranges of species to reveal that Indo-Pacific corals are assembled within 11 distinct faunal provinces. Province limits are characterized by co-occurrence of multiple species range boundaries. Unexpectedly, these faunal breaks are poorly predicted by contemporary environmental conditions and the present-day distribution of habitat. Instead, faunal breaks show striking concordance with geological features (tectonic plates and mantle plume tracks). The depth range over which a species occurs, its larval development rate and genus age are important determinants of the likelihood that species will straddle faunal breaks. Our findings indicate that historical processes, habitat heterogeneity and species colonization ability account for more of the present-day biogeographical patterns of corals than explanations based on the contemporary distribution of reefs or environmental conditions.

Faunal breaks and species composition of Indo-Pacific corals: the role of plate tectonics, environment and habitat distribution

PubMed Central

Keith, S. A.; Baird, A. H.; Hughes, T. P.; Madin, J. S.; Connolly, S. R.

2013-01-01

Species richness gradients are ubiquitous in nature, but the mechanisms that generate and maintain these patterns at macroecological scales remain unresolved. We use a new approach that focuses on overlapping geographical ranges of species to reveal that Indo-Pacific corals are assembled within 11 distinct faunal provinces. Province limits are characterized by co-occurrence of multiple species range boundaries. Unexpectedly, these faunal breaks are poorly predicted by contemporary environmental conditions and the present-day distribution of habitat. Instead, faunal breaks show striking concordance with geological features (tectonic plates and mantle plume tracks). The depth range over which a species occurs, its larval development rate and genus age are important determinants of the likelihood that species will straddle faunal breaks. Our findings indicate that historical processes, habitat heterogeneity and species colonization ability account for more of the present-day biogeographical patterns of corals than explanations based on the contemporary distribution of reefs or environmental conditions. PMID:23698011

Statistical Limits to Super Resolution

NASA Astrophysics Data System (ADS)

Lucy, L. B.

1992-08-01

The limits imposed by photon statistics on the degree to which Rayleigh's resolution limit for diffraction-limited images can be surpassed by applying image restoration techniques are investigated. An approximate statistical theory is given for the number of detected photons required in the image of an unresolved pair of equal point sources in order that its information content allows in principle resolution by restoration. This theory is confirmed by numerical restoration experiments on synthetic images, and quantitative limits are presented for restoration of diffraction-limited images formed by slit and circular apertures.

Mirror Symmetry Breaking by Chirality Synchronisation in Liquids and Liquid Crystals of Achiral Molecules.

PubMed

Tschierske, Carsten; Ungar, Goran

2016-01-04

Spontaneous mirror symmetry breaking is an efficient way to obtain homogeneously chiral agents, pharmaceutical ingredients and materials. It is also in the focus of the discussion around the emergence of uniform chirality in biological systems. Tremendous progress has been made by symmetry breaking during crystallisation from supercooled melts or supersaturates solutions and by self-assembly on solid surfaces and in other highly ordered structures. However, recent observations of spontaneous mirror symmetry breaking in liquids and liquid crystals indicate that it is not limited to the well-ordered solid state. Herein, progress in the understanding of a new dynamic mode of symmetry breaking, based on chirality synchronisation of transiently chiral molecules in isotropic liquids and in bicontinuous cubic, columnar, smectic and nematic liquid crystalline phases is discussed. This process leads to spontaneous deracemisation in the liquid state under thermodynamic control, giving rise to long-term stable symmetry-broken fluids, even at high temperatures. These fluids form conglomerates that are capable of extraordinary strong chirality amplification, eventually leading to homochirality and providing a new view on the discussion of emergence of uniform chirality in prebiotic systems. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Remote Sensing Characterization of Two-dimensional Wave Forcing in the Surf Zone

NASA Astrophysics Data System (ADS)

Carini, R. J.; Chickadel, C. C.; Jessup, A. T.

2016-02-01

In the surf zone, breaking waves drive longshore currents, transport sediment, shape bathymetry, and enhance air-sea gas and particle exchange. Furthermore, wave group forcing influences the generation and duration of rip currents. Wave breaking exhibits large gradients in space and time, making it challenging to measure in situ. Remote sensing technologies, specifically thermal infrared (IR) imagery, can provide detailed spatial and temporal measurements of wave breaking at the water surface. We construct two-dimensional maps of active wave breaking from IR imagery collected during the Surf Zone Optics Experiment in September 2010 at the US Army Corps of Engineers' Field Research Facility in Duck, NC. For each breaker identified in the camera's field of view, the crest-perpendicular length of the aerated breaking region (roller length) and wave direction are estimated and used to compute the wave energy dissipation rate. The resultant dissipation rate maps are analyzed over different time scales: peak wave period, infragravity wave period, and tidal wave period. For each time scale, spatial maps of wave breaking are used to characterize wave forcing in the surf zone for a variety of wave conditions. The following phenomena are examined: (1) wave dissipation rates over the bar (location of most intense breaking) have increased variance in infragravity wave frequencies, which are different from the peak frequency of the incoming wave field and different from the wave forcing variability at the shoreline, and (2) wave forcing has a wider spatial distribution during low tide than during high tide due to depth-limited breaking over the barred bathymetry. Future work will investigate the response of the variability in wave setup, longshore currents and rip currents, to the variability in wave forcing in the surf zone.

South Asian summer monsoon breaks: Process-based diagnostics in HIRHAM5

NASA Astrophysics Data System (ADS)

Hanf, Franziska S.; Annamalai, H.; Rinke, Annette; Dethloff, Klaus

2017-05-01

This study assesses the ability of a high-resolution downscaling simulation with the regional climate model (RCM) HIRHAM5 in capturing the monsoon basic state and boreal summer intraseasonal variability (BSISV) over South Asia with focus on moist and radiative processes during 1979-2012. A process-based vertically integrated moist static energy (MSE) budget is performed to understand the model's fidelity in representing leading processes that govern the monsoon breaks over continental India. In the climatology (June-September) HIRHAM5 simulates a dry bias over central India in association with descent throughout the free troposphere. Sources of dry bias are interpreted as (i) near-equatorial Rossby wave response forced by excess rainfall over the southern Bay of Bengal promotes anomalous descent to its northwest and (ii) excessive rainfall over near-equatorial Arabian Sea and Bay of Bengal anchor a "local Hadley-type" circulation with descent anomalies over continental India. Compared with observations HIRHAM5 captures the leading processes that account for breaks, although with generally reduced amplitudes over central India. In the model too, anomalous dry advection and net radiative cooling are responsible for the initiation and maintenance of breaks, respectively. However, weaker contributions of all adiabatic MSE budget terms, and an inconsistent relationship between negative rainfall anomalies and radiative cooling reveals shortcomings in HIRHAM5's moisture-radiation interaction. Our study directly implies that process-based budget diagnostics are necessary, apart from just checking the northward propagation feature to examine RCM's fidelity to simulate BSISV.

Simulation of breaking waves using the high-order spectral method with laboratory experiments: Wave-breaking onset

NASA Astrophysics Data System (ADS)

Seiffert, Betsy R.; Ducrozet, Guillaume; Bonnefoy, Félicien

2017-11-01

This study investigates a wave-breaking onset criteria to be implemented in the non-linear potential flow solver HOS-NWT. The model is a computationally efficient, open source code, which solves for the free surface in a numerical wave tank using the High-Order Spectral (HOS) method. The goal of this study is to determine the best method to identify the onset of random single and multiple breaking waves over a large domain at the exact time they occur. To identify breaking waves, a breaking onset criteria based on the ratio of local energy flux velocity to the local crest velocity, introduced by Barthelemy et al. (2017) is selected. The breaking parameter is uniquely applied in the numerical model in that calculations of the breaking onset criteria ratio are not made only at the location of the wave crest, but at every point in the domain and at every time step. This allows the model to calculate the onset of a breaking wave the moment it happens, and without knowing anything about the wave a priori. The application of the breaking criteria at every point in the domain and at every time step requires the phase velocity to be calculated instantaneously everywhere in the domain and at every time step. This is achieved by calculating the instantaneous phase velocity using the Hilbert transform and dispersion relation. A comparison between more traditional crest-tracking techniques shows the calculation of phase velocity using Hilbert transform at the location of the breaking wave crest provides a good approximation of crest velocity. The ability of the selected wave breaking criteria to predict single and multiple breaking events in two dimensions is validated by a series of large-scale experiments. Breaking waves are generated by energy focusing and modulational instability methods, with a wide range of primary frequencies. Steep irregular waves which lead to breaking waves, and irregular waves with an energy focusing wave superimposed are also generated. This set of waves provides a wide range of breaking-wave strengths, types and scales for validation of the model. A comparison of calculations made using HOS-NWT with experimental measurements show that the model is successful at predicting the occurrence of wave breaking, as well as accurately calculating breaking onset time and location. Although the current study is limited to a unidirectional wave field, the success of the wave-breaking model presented provides the basis for application of the model in a multidirectional wave field. By including wave breaking onset with the addition of an appropriate energy dissipation model into HOS-NWT, we can increase the application range of the model, as well as decrease the occurrence of numerical instabilities that are associated with breaking waves in a potential flow solver. An accurate description of the wave field is useful for predicting the dynamic response of offshore vessels and marine renewable energy devices, predicting loads on marine structures and the general physics of ocean waves, for example.

Stability of the Mézard-Parisi Solution for Random Manifolds

NASA Astrophysics Data System (ADS)

Carlucci, D. M.; de Dominicis, C.; Temesvari, T.

1996-08-01

The eigenvalues of the Hessian associated with random manifolds are constructed for the general case of R steps of replica symmetry breaking. For the Parisi limit Rrightarrow infty (continuum replica symmetry breaking) which is relevant for the manifold dimension D<2, they are shown to be non negative. Les valeurs propres de la hessienne, associée avec une variété aléatoire, sont construites dans le cas général de R étapes de brisure de la symétrie des répliques. Dans la limite de Parisi, Rrightarrow infty (brisure continue de la symétrie des répliques) qui est pertinente pour la dimension de la variété D<2, on montre qu'elles sont non négatives.

Acceleration of Convergence to Equilibrium in Markov Chains by Breaking Detailed Balance

NASA Astrophysics Data System (ADS)

Kaiser, Marcus; Jack, Robert L.; Zimmer, Johannes

2017-07-01

We analyse and interpret the effects of breaking detailed balance on the convergence to equilibrium of conservative interacting particle systems and their hydrodynamic scaling limits. For finite systems of interacting particles, we review existing results showing that irreversible processes converge faster to their steady state than reversible ones. We show how this behaviour appears in the hydrodynamic limit of such processes, as described by macroscopic fluctuation theory, and we provide a quantitative expression for the acceleration of convergence in this setting. We give a geometrical interpretation of this acceleration, in terms of currents that are antisymmetric under time-reversal and orthogonal to the free energy gradient, which act to drive the system away from states where (reversible) gradient-descent dynamics result in slow convergence to equilibrium.

Search for supersymmetry with gauge-mediated breaking in diphoton events with missing transverse energy at CDF II.

PubMed

Aaltonen, T; Adelman, J; Alvarez González, B; Amerio, S; Amidei, D; Anastassov, A; Annovi, A; Antos, J; Apollinari, G; Apresyan, A; Arisawa, T; Artikov, A; Asaadi, J; Ashmanskas, W; Attal, A; Aurisano, A; Azfar, F; Badgett, W; Barbaro-Galtieri, A; Barnes, V E; Barnett, B A; Barria, P; Bartos, P; Bauer, G; Beauchemin, P-H; Bedeschi, F; Beecher, D; Behari, S; Bellettini, G; Bellinger, J; Benjamin, D; Beretvas, A; Bhatti, A; Binkley, M; Bisello, D; Bizjak, I; Blair, R E; Blocker, C; Blumenfeld, B; Bocci, A; Bodek, A; Boisvert, V; Bortoletto, D; Boudreau, J; Boveia, A; Brau, B; Bridgeman, A; Brigliadori, L; Bromberg, C; Brubaker, E; Budagov, J; Budd, H S; Budd, S; Burkett, K; Busetto, G; Bussey, P; Buzatu, A; Byrum, K L; Cabrera, S; Calancha, C; Camarda, S; Campanelli, M; Campbell, M; Canelli, F; Canepa, A; Carls, B; Carlsmith, D; Carosi, R; Carrillo, S; Carron, S; Casal, B; Casarsa, M; Castro, A; Catastini, P; Cauz, D; Cavaliere, V; Cavalli-Sforza, M; Cerri, A; Cerrito, L; Chang, S H; Chen, Y C; Chertok, M; Chiarelli, G; Chlachidze, G; Chlebana, F; Cho, K; Chokheli, D; Chou, J P; Choudalakis, G; Chung, K; Chung, W H; Chung, Y S; Chwalek, T; Ciobanu, C I; Ciocci, M A; Clark, A; Clark, D; Compostella, G; Convery, M E; Conway, J; Corbo, M; Cordelli, M; Cox, C A; Cox, D J; Crescioli, F; Cuenca Almenar, C; Cuevas, J; Culbertson, R; Cully, J C; Dagenhart, D; Datta, M; Davies, T; de Barbaro, P; De Cecco, S; Deisher, A; De Lorenzo, G; Dell'Orso, M; Deluca, C; Demortier, L; Deng, J; Deninno, M; d'Errico, M; Di Canto, A; di Giovanni, G P; Di Ruzza, B; Dittmann, J R; D'Onofrio, M; Donati, S; Dong, P; Dorigo, T; Dube, S; Ebina, K; Elagin, A; Erbacher, R; Errede, D; Errede, S; Ershaidat, N; Eusebi, R; Fang, H C; Farrington, S; Fedorko, W T; Feild, R G; Feindt, M; Fernandez, J P; Ferrazza, C; Field, R; Flanagan, G; Forrest, R; Frank, M J; Franklin, M; Freeman, J C; Furic, I; Gallinaro, M; Galyardt, J; Garberson, F; Garcia, J E; Garfinkel, A F; Garosi, P; Genser, K; Gerberich, H; Gerdes, D; Gessler, A; Giagu, S; Giakoumopoulou, V; Giannetti, P; Gibson, K; Gimmell, J L; Ginsburg, C M; Giokaris, N; Giordani, M; Giromini, P; Giunta, M; Giurgiu, G; Glagolev, V; Glenzinski, D; Gold, M; Goldschmidt, N; Golossanov, A; Gomez, G; Gomez-Ceballos, G; Goncharov, M; González, O; Gorelov, I; Goshaw, A T; Goulianos, K; Gresele, A; Grinstein, S; Grosso-Pilcher, C; Group, R C; Grundler, U; Guimaraes da Costa, J; Gunay-Unalan, Z; Haber, C; Hahn, K; Hahn, S R; Halkiadakis, E; Han, B-Y; Han, J Y; Happacher, F; Hara, K; Hare, D; Hare, M; Harr, R F; Hartz, M; Hatakeyama, K; Hays, C; Heck, M; Heinrich, J; Henderson, C; Herndon, M; Heuser, J; Hewamanage, S; Hidas, D; Hill, C S; Hirschbuehl, D; Hocker, A; Hou, S; Houlden, M; Hsu, S-C; Huffman, B T; Hughes, R E; Hurwitz, M; Husemann, U; Hussein, M; Huston, J; Incandela, J; Introzzi, G; Iori, M; Ivanov, A; James, E; Jang, D; Jayatilaka, B; Jeon, E J; Jha, M K; Jindariani, S; Johnson, W; Jones, M; Joo, K K; Jun, S Y; Jung, J E; Junk, T R; Kamon, T; Kar, D; Karchin, P E; Kato, Y; Kephart, R; Ketchum, W; Keung, J; Khotilovich, V; Kilminster, B; Kim, D H; Kim, H S; Kim, H W; Kim, J E; Kim, M J; Kim, S B; Kim, S H; Kim, Y K; Kimura, N; Kirsch, L; Klimenko, S; Knuteson, B; Kondo, K; Kong, D J; Konigsberg, J; Korytov, A; Kotwal, A V; Kreps, M; Kroll, J; Krop, D; Krumnack, N; Kruse, M; Krutelyov, V; Kuhr, T; Kulkarni, N P; Kurata, M; Kwang, S; Laasanen, A T; Lami, S; Lammel, S; Lancaster, M; Lander, R L; Lannon, K; Lath, A; Latino, G; Lazzizzera, I; LeCompte, T; Lee, E; Lee, H S; Lee, J S; Lee, S W; Leone, S; Lewis, J D; Lin, C-J; Linacre, J; Lindgren, M; Lipeles, E; Lister, A; Litvintsev, D O; Liu, C; Liu, T; Lockyer, N S; Loginov, A; Lovas, L; Lucchesi, D; Lueck, J; Lujan, P; Lukens, P; Lungu, G; Lys, J; Lysak, R; MacQueen, D; Madrak, R; Maeshima, K; Makhoul, K; Maksimovic, P; Malde, S; Malik, S; Manca, G; Manousakis-Katsikakis, A; Margaroli, F; Marino, C; Marino, C P; Martin, A; Martin, V; Martínez, M; Martínez-Ballarín, R; Mastrandrea, P; Mathis, M; Mattson, M E; Mazzanti, P; McFarland, K S; McIntyre, P; McNulty, R; Mehta, A; Mehtala, P; Menzione, A; Mesropian, C; Miao, T; Mietlicki, D; Miladinovic, N; Miller, R; Mills, C; Milnik, M; Mitra, A; Mitselmakher, G; Miyake, H; Moed, S; Moggi, N; Mondragon, M N; Moon, C S; Moore, R; Morello, M J; Morlock, J; Movilla Fernandez, P; Mülmenstädt, J; Mukherjee, A; Muller, Th; Murat, P; Mussini, M; Nachtman, J; Nagai, Y; Naganoma, J; Nakamura, K; Nakano, I; Napier, A; Nett, J; Neu, C; Neubauer, M S; Neubauer, S; Nielsen, J; Nodulman, L; Norman, M; Norniella, O; Nurse, E; Oakes, L; Oh, S H; Oh, Y D; Oksuzian, I; Okusawa, T; Orava, R; Osterberg, K; Pagan Griso, S; Pagliarone, C; Palencia, E; Papadimitriou, V; Papaikonomou, A; Paramanov, A A; Parks, B; Pashapour, S; Patrick, J; Pauletta, G; Paulini, M; Paus, C; Peiffer, T; Pellett, D E; Penzo, A; Phillips, T J; Piacentino, G; Pianori, E; Pinera, L; Pitts, K; Plager, C; Pondrom, L; Potamianos, K; Poukhov, O; Prokoshin, F; Pronko, A; Ptohos, F; Pueschel, E; Punzi, G; Pursley, J; Rademacker, J; Rahaman, A; Ramakrishnan, V; Ranjan, N; Redondo, I; Renton, P; Renz, M; Rescigno, M; Richter, S; Rimondi, F; Ristori, L; Robson, A; Rodrigo, T; Rodriguez, T; Rogers, E; Rolli, S; Roser, R; Rossi, M; Rossin, R; Roy, P; Ruiz, A; Russ, J; Rusu, V; Rutherford, B; Saarikko, H; Safonov, A; Sakumoto, W K; Santi, L; Sartori, L; Sato, K; Savoy-Navarro, A; Schlabach, P; Schmidt, A; Schmidt, E E; Schmidt, M A; Schmidt, M P; Schmitt, M; Schwarz, T; Scodellaro, L; Scribano, A; Scuri, F; Sedov, A; Seidel, S; Seiya, Y; Semenov, A; Sexton-Kennedy, L; Sforza, F; Sfyrla, A; Shalhout, S Z; Shears, T; Shepard, P F; Shimojima, M; Shiraishi, S; Shochet, M; Shon, Y; Shreyber, I; Simonenko, A; Sinervo, P; Sisakyan, A; Slaughter, A J; Slaunwhite, J; Sliwa, K; Smith, J R; Snider, F D; Snihur, R; Soha, A; Somalwar, S; Sorin, V; Spreitzer, T; Squillacioti, P; Stanitzki, M; St Denis, R; Stelzer, B; Stelzer-Chilton, O; Stentz, D; Strologas, J; Strycker, G L; Suh, J S; Sukhanov, A; Suslov, I; Taffard, A; Takashima, R; Takeuchi, Y; Tanaka, R; Tang, J; Tecchio, M; Teng, P K; Thom, J; Thome, J; Thompson, G A; Thomson, E; Tipton, P; Ttito-Guzmán, P; Tkaczyk, S; Toback, D; Tokar, S; Tollefson, K; Tomura, T; Tonelli, D; Torre, S; Torretta, D; Totaro, P; Tourneur, S; Trovato, M; Tsai, S-Y; Tu, Y; Turini, N; Ukegawa, F; Uozumi, S; van Remortel, N; Varganov, A; Vataga, E; Vázquez, F; Velev, G; Vellidis, C; Vidal, M; Vila, I; Vilar, R; Vogel, M; Volobouev, I; Volpi, G; Wagner, P; Wagner, R G; Wagner, R L; Wagner, W; Wagner-Kuhr, J; Wakisaka, T; Wallny, R; Wang, S M; Warburton, A; Waters, D; Weinberger, M; Weinelt, J; Wester, W C; Whitehouse, B; Whiteson, D; Wicklund, A B; Wicklund, E; Wilbur, S; Williams, G; Williams, H H; Wilson, P; Winer, B L; Wittich, P; Wolbers, S; Wolfe, C; Wolfe, H; Wright, T; Wu, X; Würthwein, F; Xie, S; Yagil, A; Yamamoto, K; Yamaoka, J; Yang, U K; Yang, Y C; Yao, W M; Yeh, G P; Yi, K; Yoh, J; Yorita, K; Yoshida, T; Yu, G B; Yu, I; Yu, S S; Yun, J C; Zanetti, A; Zeng, Y; Zhang, X; Zheng, Y; Zucchelli, S

2010-01-08

We present the results of a search for supersymmetry with gauge-mediated breaking and chi(1)(0) --> gammaG in the gammagamma + missing transverse energy final state. In 2.6+/-0.2 fb(-1) of pp collisions at square root(s) = 1.96 TeV recorded by the CDF II detector we observe no candidate events, consistent with a standard model background expectation of 1.4+/-0.4 events. We set limits on the cross section at the 95% C.L. and place the world's best limit of 149 GeV/c2 on the chi(1)(0) mass at tau(chi(1)(0)) < 1 ns. We also exclude regions in the chi(1)(0) mass-lifetime plane for tau(chi(1)(0)) approximately < 2 ns.

Electromagnetic properties of impure superconductors with pair-breaking processes

NASA Astrophysics Data System (ADS)

Herman, František; Hlubina, Richard

2017-07-01

Recently, a generic model was proposed for the single-particle properties of gapless superconductors with simultaneously present pair-conserving and pair-breaking impurity scatterings (the so-called Dynes superconductors). Here we calculate the optical conductivity of the Dynes superconductors. Our approach is applicable for all disorder strengths from the clean limit up to the dirty limit and for all relative ratios of the two types of scattering; nevertheless, the complexity of our description is equivalent to that of the widely used Mattis-Bardeen theory. We identify two optical fingerprints of the Dynes superconductors: (i) the presence of two absorption edges and (ii) finite absorption at vanishing frequencies even at the lowest temperatures. We demonstrate that the recent anomalous optical data on thin MoN films can be reasonably fitted by our theory.

Breaking the theoretical scaling limit for predicting quasiparticle energies: the stochastic GW approach.

PubMed

Neuhauser, Daniel; Gao, Yi; Arntsen, Christopher; Karshenas, Cyrus; Rabani, Eran; Baer, Roi

2014-08-15

We develop a formalism to calculate the quasiparticle energy within the GW many-body perturbation correction to the density functional theory. The occupied and virtual orbitals of the Kohn-Sham Hamiltonian are replaced by stochastic orbitals used to evaluate the Green function G, the polarization potential W, and, thereby, the GW self-energy. The stochastic GW (sGW) formalism relies on novel theoretical concepts such as stochastic time-dependent Hartree propagation, stochastic matrix compression, and spatial or temporal stochastic decoupling techniques. Beyond the theoretical interest, the formalism enables linear scaling GW calculations breaking the theoretical scaling limit for GW as well as circumventing the need for energy cutoff approximations. We illustrate the method for silicon nanocrystals of varying sizes with N_{e}>3000 electrons.

3D DNS and LES of Breaking Inertia-Gravity Waves

NASA Astrophysics Data System (ADS)

Remmler, S.; Fruman, M. D.; Hickel, S.; Achatz, U.

2012-04-01

As inertia-gravity waves we refer to gravity waves that have a sufficiently low frequency and correspondingly large horizontal wavelength to be strongly influenced by the Coriolis force. Inertia-gravity waves are very active in the middle atmosphere and their breaking is potentially an important influence on the circulation in this region. The parametrization of this process requires a good theoretical understanding, which we want to enhance with the present study. Primary linear instabilities of an inertia-gravity wave and "2.5-dimensional" nonlinear simulations (where the spatial dependence is two dimensional but the velocity and vorticity fields are three-dimensional) with the wave perturbed by its leading primary instabilities by Achatz [1] have shown that the breaking differs significantly from that of high-frequency gravity waves due to the strongly sheared component of velocity perpendicular to the plane of wave-propagation. Fruman & Achatz [2] investigated the three-dimensionalization of the breaking by computing the secondary linear instabilities of the same waves using singular vector analysis. These secondary instabilities are variations perpendicular to the direction of the primary perturbation and the wave itself, and their wavelengths are an order of magnitude shorter than both. In continuation of this work, we carried out fully three-dimensional nonlinear simulations of inertia-gravity waves perturbed by their leading primary and secondary instabilities. The direct numerical simulation (DNS) was made tractable by restricting the domain size to the dominant scales selected by the linear analyses. The study includes both convectively stable and unstable waves. To the best of our knowledge, this is the first fully three-dimensional nonlinear direct numerical simulation of inertia-gravity waves at realistic Reynolds numbers with complete resolution of the smallest turbulence scales. Previous simulations either were restricted to high frequency gravity waves (e. g. Fritts et al. [3]), or the ratio N/f was artificially reduced (e. g. Lelong & Dunkerton [4]). The present simulations give us insight into the three-dimensional breaking process as well as the emerging turbulence. We assess the possibility of reducing the computational costs of three-dimensional simulations by using an implicit turbulence subgrid-scale parametrization based on the Adaptive Local Deconvolution Method (ALDM) for stratified turbulence [5]. In addition, we have performed ensembles of nonlinear 2.5-dimensional DNS, like those in Achatz [1] but with a small amount of noise superposed to the initial state, and compared the results with coarse-resolution simulations using either ALDM as well as with standard LES schemes. We found that the results of the models with parametrized turbulence, which are orders of magnitude more computationally economical than the DNS, compare favorably with the DNS in terms of the decay of the wave amplitude with time (the quantity most important for application to gravity-wave drag parametrization) suggesting that they may be trusted in future simulations of gravity wave breaking.

Multiplicity of High-z Submillimeter Galaxies from Cosmological Simulations

NASA Astrophysics Data System (ADS)

Ball, David; Narayanan, Desika; Hopkins, Philip F.; Turk, Matthew

2015-01-01

Sub-millimeter galaxies (or SMG's) are some of the most luminous galaxies in the universe, yet are nearly invisible in the optical. Theorists have long struggled to simulate SMG's and accurately match their spectral properties and abundance to observations. Recent high-resolution observations, however, suggest that what were previously thought to be single sub-millimeter sources on the sky, may break up into multiple components when viewed with sufficient resolving power. Here, we present a combination of high-resolution cosmological hydrodynamic zoom simulations of massive galaxies in formation with a new dust radiative transfer package in order to understand this multiplicity in simulated SMGs. We find that multiplicity is a natural element of SMG formation as numerous subhalos bombard the central during its peak growth phase

Swarm v2: highly-scalable and high-resolution amplicon clustering.

PubMed

Mahé, Frédéric; Rognes, Torbjørn; Quince, Christopher; de Vargas, Colomban; Dunthorn, Micah

2015-01-01

Previously we presented Swarm v1, a novel and open source amplicon clustering program that produced fine-scale molecular operational taxonomic units (OTUs), free of arbitrary global clustering thresholds and input-order dependency. Swarm v1 worked with an initial phase that used iterative single-linkage with a local clustering threshold (d), followed by a phase that used the internal abundance structures of clusters to break chained OTUs. Here we present Swarm v2, which has two important novel features: (1) a new algorithm for d = 1 that allows the computation time of the program to scale linearly with increasing amounts of data; and (2) the new fastidious option that reduces under-grouping by grafting low abundant OTUs (e.g., singletons and doubletons) onto larger ones. Swarm v2 also directly integrates the clustering and breaking phases, dereplicates sequencing reads with d = 0, outputs OTU representatives in fasta format, and plots individual OTUs as two-dimensional networks.

A Lyman Break Galaxy in the Epoch of Reionization from Hubble Space Telescope (HST) Grism Spectroscopy

NASA Technical Reports Server (NTRS)

Rhoads, James E.; Malhotra, Sangeeta; Stern, Daniel K.; Gardner, Jonathan P.; Dickinson, Mark; Pirzkal, Norbert; Spinrad, Hyron; Reddy, Naveen; Dey, Arjun; Hathi, Nimish;

Visualization of complex DNA double-strand breaks in a tumor treated with carbon ion radiotherapy

PubMed Central

Oike, Takahiro; Niimi, Atsuko; Okonogi, Noriyuki; Murata, Kazutoshi; Matsumura, Akihiko; Noda, Shin-Ei; Kobayashi, Daijiro; Iwanaga, Mototaro; Tsuchida, Keisuke; Kanai, Tatsuaki; Ohno, Tatsuya; Shibata, Atsushi; Nakano, Takashi

2016-01-01

Carbon ion radiotherapy shows great potential as a cure for X-ray-resistant tumors. Basic research suggests that the strong cell-killing effect induced by carbon ions is based on their ability to cause complex DNA double-strand breaks (DSBs). However, evidence supporting the formation of complex DSBs in actual patients is lacking. Here, we used advanced high-resolution microscopy with deconvolution to show that complex DSBs are formed in a human tumor clinically treated with carbon ion radiotherapy, but not in a tumor treated with X-ray radiotherapy. Furthermore, analysis using a physics model suggested that the complexity of radiotherapy-induced DSBs is related to linear energy transfer, which is much higher for carbon ion beams than for X-rays. Visualization of complex DSBs in clinical specimens will help us to understand the anti-tumor effects of carbon ion radiotherapy. PMID:26925533

Nontrivial Critical Fixed Point for Replica-Symmetry-Breaking Transitions.

PubMed

Charbonneau, Patrick; Yaida, Sho

2017-05-26

The transformation of the free-energy landscape from smooth to hierarchical is one of the richest features of mean-field disordered systems. A well-studied example is the de Almeida-Thouless transition for spin glasses in a magnetic field, and a similar phenomenon-the Gardner transition-has recently been predicted for structural glasses. The existence of these replica-symmetry-breaking phase transitions has, however, long been questioned below their upper critical dimension, d_{u}=6. Here, we obtain evidence for the existence of these transitions in d

Kinetic energy spectra, vertical resolution and dissipation in high-resolution atmospheric simulations.

NASA Astrophysics Data System (ADS)

Skamarock, W. C.

2017-12-01

We have performed week-long full-physics simulations with the MPAS global model at 15 km cell spacing using vertical mesh spacings of 800, 400, 200 and 100 meters in the mid-troposphere through the mid-stratosphere. We find that the horizontal kinetic energy spectra in the upper troposphere and stratosphere does not converge with increasing vertical resolution until we reach 200 meter level spacing. Examination of the solutions indicates that significant inertia-gravity waves are not vertically resolved at the lower vertical resolutions. Diagnostics from the simulations indicate that the primary kinetic energy dissipation results from the vertical mixing within the PBL parameterization and from the gravity-wave drag parameterization, with smaller but significant contributions from damping in the vertical transport scheme and from the horizontal filters in the dynamical core. Most of the kinetic energy dissipation in the free atmosphere occurs within breaking mid-latitude baroclinic waves. We will briefly review these results and their implications for atmospheric model configuration and for atmospheric dynamics, specifically that related to the dynamics associated with the mesoscale kinetic energy spectrum.

Atmospheric blocking in the Climate SPHINX simulations: the role of orography and resolution

NASA Astrophysics Data System (ADS)

Davini, Paolo; Corti, Susanna; D'Andrea, Fabio; Riviere, Gwendal; von Hardenberg, Jost

2017-04-01

The representation of atmospheric blocking in numerical simulations, especially over the Euro-Atlantic region, still represents a main concern for the climate modelling community. We here discuss the Northern Hemisphere winter atmospheric blocking representation in a set of 30-year simulations which has been performed in the framework of the PRACE project "Climate SPHINX". Simulations were run using the EC-Earth Global Climate Model with several ensemble members at 5 different horizontal resolutions (ranging from 125 km to 16 km). Results show that the negative bias in blocking frequency over Europe becomes negligible at resolutions of about 40 km and finer. However, the blocking duration is still underestimated by 1-2 days, suggesting that the correct blocking frequencies are achieved with an overestimation of the number of blocking onsets. The reasons leading to such improvements are then discussed, highlighting the role of orography in shaping the Atlantic jet stream: at higher resolution the jet is weaker and less penetrating over Europe, favoring the breaking of synoptic Rossby waves over the Atlantic stationary ridge and thus increasing the simulated blocking frequency.

Visible light optical coherence microscopy imaging of the mouse cortex with femtoliter volume resolution

NASA Astrophysics Data System (ADS)

Merkle, Conrad W.; Chong, Shau Poh; Kho, Aaron M.; Zhu, Jun; Kholiqov, Oybek; Dubra, Alfredo; Srinivasan, Vivek J.

2018-02-01

Most flying-spot Optical Coherence Tomography (OCT) and Optical Coherence Microscopy (OCM) systems use a symmetric confocal geometry, where the detection path retraces the illumination path starting from and ending with the spatial mode of a single mode optical fiber. Here, we describe a visible light OCM instrument that breaks this symmetry to improve transverse resolution without sacrificing collection efficiency in scattering tissue. This was achieved by overfilling a 0.3 numerical aperture (NA) water immersion objective on the illumination path, while maintaining a conventional Gaussian mode detection path (1/e2 intensity diameter 0.82 Airy disks), enabling 1.1 μm full-width at half-maximum (FWHM) transverse resolution. At the same time, a 0.9 μm FWHM axial resolution in tissue, achieved by a broadband visible light source, enabled femtoliter volume resolution. We characterized this instrument according to paraxial coherent microscopy theory, and then used it to image the meningeal layers, intravascular red blood cell-free layer, and myelinated axons in the mouse neocortex in vivo through the thinned skull. Finally, by introducing a 0.8 NA water immersion objective, we improved the lateral resolution to 0.44 μm FWHM, which provided a volumetric resolution of 0.2 fL, revealing cell bodies in cortical layer I of the mouse brain with OCM for the first time.

Super-resolution fluorescence microscopy by stepwise optical saturation

PubMed Central

Zhang, Yide; Nallathamby, Prakash D.; Vigil, Genevieve D.; Khan, Aamir A.; Mason, Devon E.; Boerckel, Joel D.; Roeder, Ryan K.; Howard, Scott S.

2018-01-01

Super-resolution fluorescence microscopy is an important tool in biomedical research for its ability to discern features smaller than the diffraction limit. However, due to its difficult implementation and high cost, the super-resolution microscopy is not feasible in many applications. In this paper, we propose and demonstrate a saturation-based super-resolution fluorescence microscopy technique that can be easily implemented and requires neither additional hardware nor complex post-processing. The method is based on the principle of stepwise optical saturation (SOS), where M steps of raw fluorescence images are linearly combined to generate an image with a M-fold increase in resolution compared with conventional diffraction-limited images. For example, linearly combining (scaling and subtracting) two images obtained at regular powers extends the resolution by a factor of 1.4 beyond the diffraction limit. The resolution improvement in SOS microscopy is theoretically infinite but practically is limited by the signal-to-noise ratio. We perform simulations and experimentally demonstrate super-resolution microscopy with both one-photon (confocal) and multiphoton excitation fluorescence. We show that with the multiphoton modality, the SOS microscopy can provide super-resolution imaging deep in scattering samples. PMID:29675306

Hyperscaling breakdown and Ising spin glasses: The Binder cumulant

NASA Astrophysics Data System (ADS)

Lundow, P. H.; Campbell, I. A.

2018-02-01

Among the Renormalization Group Theory scaling rules relating critical exponents, there are hyperscaling rules involving the dimension of the system. It is well known that in Ising models hyperscaling breaks down above the upper critical dimension. It was shown by Schwartz (1991) that the standard Josephson hyperscaling rule can also break down in Ising systems with quenched random interactions. A related Renormalization Group Theory hyperscaling rule links the critical exponents for the normalized Binder cumulant and the correlation length in the thermodynamic limit. An appropriate scaling approach for analyzing measurements from criticality to infinite temperature is first outlined. Numerical data on the scaling of the normalized correlation length and the normalized Binder cumulant are shown for the canonical Ising ferromagnet model in dimension three where hyperscaling holds, for the Ising ferromagnet in dimension five (so above the upper critical dimension) where hyperscaling breaks down, and then for Ising spin glass models in dimension three where the quenched interactions are random. For the Ising spin glasses there is a breakdown of the normalized Binder cumulant hyperscaling relation in the thermodynamic limit regime, with a return to size independent Binder cumulant values in the finite-size scaling regime around the critical region.

Pushing the limits of spatial resolution with the Kuiper Airborne observatory

NASA Technical Reports Server (NTRS)

Lester, Daniel

1994-01-01

The study of astronomical objects at high spatial resolution in the far-IR is one of the most serious limitations to our work at these wavelengths, which carry information about the luminosity of dusty and obscured sources. At IR wavelengths shorter than 30 microns, ground based telescopes with large apertures at superb sites achieve diffraction-limited performance close to the seeing limit in the optical. At millimeter wavelengths, ground based interferometers achieve resolution that is close to this. The inaccessibility of the far-IR from the ground makes it difficult, however, to achieve complementary resolution in the far-IR. The 1983 IRAS survey, while extraordinarily sensitive, provides us with a sky map at a spatial resolution that is limited by detector size on a spatial scale that is far larger than that available in other wavelengths on the ground. The survey resolution is of order 4 min in the 100 micron bandpass, and 2 min at 60 microns (IRAS Explanatory Supplement, 1988). Information on a scale of 1' is available on some sources from the CPC. Deconvolution and image resolution using this database is one of the subjects of this workshop.

Fecal microbiota transplantation for Clostridium difficile infection: systematic review and meta-analysis.

PubMed

Kassam, Zain; Lee, Christine H; Yuan, Yuhong; Hunt, Richard H

2013-04-01

The clinical and economic burden of Clostridium difficile infection (CDI) is significant. Recurrent CDI management has emerged as a major challenge with suboptimal response to standard therapy. Fecal microbiota transplantation (FMT) has been used as a treatment to reconstitute the normal microbial homeostasis and break the cycle of antibiotic agents that may further disrupt the microbiome. Given the lack of randomized-controlled trials (RCTs) and limitations in previous systematic reviews, we aimed to conduct a systematic review with robust methods to determine the efficacy and safety profile of FMT in CDI. An electronic search was conducted using MEDLINE (1946-March 2012), EMBASE (1974-March 2012) and Cochrane Central Register of Controlled Trials (2012). The search strategy was not limited by language. Abstract data were excluded and only completed studies that underwent the full, rigorous peer-review process were included. Studies that used FMT via any delivery modality for laboratory or endoscopically proven CDI with clinical resolution as primary outcome were included. A sample size of 10 or more patients was a further criterion. Elements of the Centre for Reviews and Dissemination checklist and the National Institute of Clinical Excellence quality assessment for case series checklist were employed to determine study quality. Eligibility assessment and data extraction were performed by two independent researchers. Both unweighted pooled resolution rates (UPR) and weighted pooled resolution rates (WPR) were calculated with corresponding 95% confidence intervals (CI) for overall studies, as well as predefined subgroups. Eleven studies with a total of 273 CDI patients treated with FMT were identified; no RCTs were found as none have been published. Two-hundred and forty-five out of 273 patients experienced clinical resolution (UPR 89.7%; WPR 89.1% (95% CI 84 to 93%)). There was no statistically significant heterogeneity between studies (Cochran Q test P=0.13, I(2)=33.7%). A priori subgroup analysis suggested that lower gastrointestinal FMT delivery (UPR 91.4%; WPR 91.2% (95% CI 86 to 95%)) led to a trend towards higher clinical resolution rates than the upper gastrointestinal route (UPR 82.3%; WPR 80.6% (95% CI 69-90%)) (proportion difference of WPR was 10.6% (95% CI -0.6 to 22%)). No difference in clinical outcomes was detected between anonymous vs. patient selected donors. There were no reported adverse events associated with FMT and follow-up was variable from weeks to years. FMT holds considerable promise as a therapy for recurrent CDI but well-designed, RCTs and long-term follow-up registries are still required. These are needed to identify the right patient, efficacy and safety profile of FMT before this approach can be widely advocated.

The Case for Space-Borne Far-Infrared Line Surveys

NASA Technical Reports Server (NTRS)

Bock, J. J.; Bradford, C. M.; Dragovan, M.; Earle, L.; Glenn, J.; Naylor, B.; Nguyen, H. T.; Zmuidzinas, J.

2004-01-01

The combination of sensitive direct detectors and a cooled aperture promises orders of magnitude improvement in the sensitivity and survey time for far-infrared and submillimeter spectroscopy compared to existing or planned capabilities. Continuing advances in direct detector technology enable spectroscopy that approaches the background limit available only from space at these wavelengths. Because the spectral confusion limit is significantly lower than the more familiar spatial confusion limit encountered in imaging applications, spectroscopy can be carried out to comparable depth with a significantly smaller aperture. We are developing a novel waveguide-coupled grating spectrometer that disperses radiation into a wide instantaneous bandwidth with moderate resolution (R 1000) in a compact 2-dimensional format. A line survey instrument coupled to a modest cooled single aperture provides an attractive scientific application for spectroscopy with direct detectors. Using a suite of waveguide spectrometers, we can obtain complete coverage over the entire far-infrared and sub-millimeter. This concept requires no moving parts to modulate the optical signal. Such an instrument would be able to conduct a far-infrared line survey 10 6 times faster than planned capabilities, assuming existing detector technology. However, if historical improvements in bolometer sensitivity continue, so that photon-limited sensitivity is obtained, the integration time can be further reduced by 2 to 4 orders of magnitude, depending on wavelength. The line flux sensitivity would be comparable to ALMA, but at shorter wavelengths and with the continuous coverage needed to extract line fluxes for sources at unknown redshifts. For example, this capability would break the current spectroscopic bottleneck in the study of far-infrared galaxies, the recently discovered, rapidly evolving objects abundant at cosmological distances.

The Extragalactic Lens VLBI Imaging Survey (ELVIS): Investigating galaxy cores and black holes with gravitational lens central images

NASA Astrophysics Data System (ADS)

Boyce, Edward R.

This thesis describes the Extragalactic Lens VLBI Imaging Survey (ELVIS), a search for central images in gravitational lenses. We present the first four ELVIS targets, for which we have radio VLBI observations with resolutions of a few milli-arcseconds and sensitivities of 15 - 38mJy. For PMN J1838-3427, CLASS B0739+366 and CLASS B0445+123 we have not detected any central images, but have set stringent upper limits on their flux densities. For CLASS B2319+051 we have made a tentative detection of a third radio source, which may be either a central image or radio emission from the lens galaxy. Using the upper limits on the central image flux densities, we gain new information about the matter distributions in the lens galaxies of these systems. We fit a broken power law model for the matter profile, and constrain the allowed break radii and inner index of this model. To demagnify the central images to the observed level the matter profiles must be slightly shallower than or steeper than isothermal, which is consistent with previous studies of early type galaxy profiles. The presence of a super-massive black hole weakens the constraints somewhat, but the profiles are still close to isothermal. Relative to previous work, we reduce the maximum sizes of shallow cores by factors of 2 to 3, and raise the indices of r 0( r -g central cusps by g = 0.05 - 0.35. If we take the source in B2319+051 to be a central image, then we select a narrow band of allowed break radii and inner indices, finding that a constant density core has size 150--380 pc, and a pure power law has index g = 1.5 - 1.67. Our constraints still allow sufficiently shallow profiles that some super-massive black holes may form central image pairs rather than eliminating the central image, and these image pairs may be detected with future instruments. (Copies available exclusively from MIT Libraries, Rm. 14-0551, Cambridge, MA 02139-4307. Ph. 617-253-5668; Fax 617-253-1690.)

East Antarctic ice-sheet dynamics between 5.2 and 0 Ma from a high-resolution terrigenous particle size record, ODP Site 1165, Prydz Bay-Cooperation Sea

USGS Publications Warehouse

Passchier, S.

2007-01-01

This paper discusses a 5.2-0 Ma high-resolution terrigenous particle size record recovered from a sediment drift off East Antarctica. The particle size properties of Hole 1165B are interpreted in the context of previously acquired data on a continental shelf to slope transect drilled by ODP Leg 188 in Prydz Bay and the Cooperation Sea. The new data indicate that the Lambert ice stream stayed predominantly landward of the shelf break in the early Pliocene (5.2-3.5 Ma) with periods of ice sheet recession on land. The middle Pliocene (3.5-3.1 Ma) is characterized as major ice expansion during glacials with deposition of laminated clays from meltwater plumes on the continental rise, alternating with periods of ice recession. A change in sedimentary facies and a decrease in sedimentation rates occurred at ~3.1 Ma indicating a more retreated Lambert Glacier. Between 2.5 and 1 Ma the ice stream was generally stable and had become cold-based with ice flow in a glacial trough extending to the shelf break. Three-four large pulses of coarse-grained glacigenic debris mark the record at ~1 Ma. These are interpreted as extensive calving due to decoupling of the marine terminus from its bed in response to Northern Hemisphere deglaciations and associated sea level rises.

Global simulation of flux transfer events: Generation mechanism and spacecraft signatures

NASA Astrophysics Data System (ADS)

Raeder, J.

We use global MHD simulations of Earth's magnetosphere to show that for southward IMF conditions: a) steady reconnection preferentially occurs without FTEs when the stagnation flow line nearly coincides with the X-line location, which requires small dipole tilt and nearly due southward IMF, b) FTEs occur when the flow/field symmetry is broken, which requires either a large dipole tilt and/or a substantial east-west component of the IMF, c) the predicted spacecraft signature and the repetition frequency of FTEs in the simulations agrees very well with typical observations, lending credibility to the the model, d) the fundamental process that leads to FTE formation is multiple X-line formation caused by the flow and field patterns in the magnetosheath and requires no intrinsic plasma property variations like variable resistivity, e) if the dipole tilt breaks the symmetry FTEs occur only in the winter hemisphere whereas the reconnection signatures in the summer hemisphere are steady with no bipolar FTE-like signatures, f) if the IMF east-west field component breaks the symmetry FTEs occur in both hemispheres but are least likely observed near the subsolar point, and g) FTE formation depends on sufficient resolution and low diffusion in the model. Too coarse resolution and/or too high diffusivity lead to flow-through reconnection signatures that appear unphysical given the frequent observation of FTEs.

Rapid identification of tomato Sw-5 resistance-breaking isolates of Tomato spotted wilt virus using high resolution melting and TaqMan SNP Genotyping assays as allelic discrimination techniques.

PubMed

di Rienzo, Valentina; Bubici, Giovanni; Montemurro, Cinzia; Cillo, Fabrizio

2018-01-01

In tomato, resistance to Tomato spotted wilt virus (TSWV) is conferred by the dominant gene, designated Sw-5. Virulent Sw-5 resistance breaking (SRB) mutants of TSWV have been reported on Sw-5 tomato cultivars. Two different PCR-based allelic discrimination techniques, namely Custom TaqMan™ SNP Genotyping and high-resolution melting (HRM) assays, were developed and compared for their ability to distinguish between avirulent (Sw-5 non-infecting, SNI) and SRB biotypes. TaqMan assays proved to be more sensitive (threshold of detection in a range of 50-70 TSWV RNA copies) and more reliable than HRM, assigning 25 TSWV isolates to their correct genotype with an accuracy of 100%. Moreover, the TaqMan SNP assays were further improved developing a rapid and simple protocol that included crude leaf extraction for RNA template preparations. On the other hand, HRM assays showed higher levels of sensitivity than TaqMan when used to co-detect both biotypes in different artificial mixtures. These diagnostic assays contributed to gain preliminary information on the epidemiology of TSWV isolates in open field conditions. In fact, the presented data suggest that SRB isolates are present as stable populations established year round, persisting on both winter (globe artichoke) and summer (tomato) crops, in the same cultivated areas of Southern Italy.

Incoherent transport for phases that spontaneously break translations

NASA Astrophysics Data System (ADS)

Donos, Aristomenis; Gauntlett, Jerome P.; Griffin, Tom; Ziogas, Vaios

2018-04-01

We consider phases of matter at finite charge density which spontaneously break spatial translations. Without taking a hydrodynamic limit we identify a boost invariant incoherent current operator. We also derive expressions for the small frequency behaviour of the thermoelectric conductivities generalising those that have been derived in a translationally invariant context. Within holographic constructions we show that the DC conductivity for the incoherent current can be obtained from a solution to a Stokes flow for an auxiliary fluid on the black hole horizon combined with specific thermodynamic quantities associated with the equilibrium black hole solutions.

Supercontinuum generation in silicon waveguides relying on wave-breaking.

PubMed

Castelló-Lurbe, David; Silvestre, Enrique

2015-10-05

Four-wave-mixing processes enabled during optical wave-breaking (OWB) are exploited in this paper for supercontinuum generation. Unlike conventional approaches based on OWB, phase-matching is achieved here for these nonlinear interactions, and, consequently, new frequency production becomes more efficient. We take advantage of this kind of pulse propagation to obtain numerically a coherent octave-spanning mid-infrared supercontinuum generation in a silicon waveguide pumping at telecom wavelengths in the normal dispersion regime. This scheme shows a feasible path to overcome limits imposed by two-photon absorption on spectral broadening in silicon waveguides.

Extraction method based on emulsion breaking for the determination of Cu, Fe and Pb in Brazilian automotive gasoline samples by high-resolution continuum source flame atomic absorption spectrometry

NASA Astrophysics Data System (ADS)

Leite, Clarice C.; de Jesus, Alexandre; Kolling, Leandro; Ferrão, Marco F.; Samios, Dimitrios; Silva, Márcia M.

2018-04-01

This work reports a new method for extraction of Cu, Fe and Pb from Brazilian automotive gasoline and their determination by high-resolution continuous source flame atomic absorption spectrometry (HR-CS FAAS). The method was based on the formation of water-in-oil emulsion by mixing 2.0 mL of extraction solution constituted by 12% (w/v) Triton X-100 and 5% (v/v) HNO3 with 10 mL of sample. After heating at 90 °C for 10 min, two well-defined phases were formed. The bottom phase (approximately 3.5 mL), composed of acidified water and part of the ethanol originally present in the gasoline sample, containing the extracted analytes was analyzed. The surfactant and HNO3 concentrations and the heating temperature employed in the process were optimized by Doehlert design, using a Brazilian gasoline sample spiked with Cu, Fe and Pb (organometallic compounds). The efficiency of extraction was investigated and it ranged from 80 to 89%. The calibration was accomplished by using matrix matching method. For this, the standards were obtained performing the same extraction procedure used for the sample, using emulsions obtained with a gasoline sample free of analytes and the addition of inorganic standards. Limits of detection obtained were 3.0, 5.0 and 14.0 μg L-1 for Cu, Fe and Pb, respectively. These limits were estimated for the original sample taking into account the preconcentration factor obtained. The accuracy of the proposed method was assured by recovery tests spiking the samples with organometallic standards and the obtained values ranged from 98 to 105%. Ten gasoline samples were analyzed and Fe was found in four samples (0.04-0.35 mg L-1) while Cu (0.28 mg L-1) and Pb (0.60 mg L-1) was found in just one sample.

Weak data do not make a free lunch, only a cheap meal

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

Luo, Zhipu; Rajashankar, Kanagalaghatta; Dauter, Zbigniew, E-mail: dauter@anl.gov

2014-02-01

Refinement and analysis of four structures with various data resolution cutoffs suggests that at present there are no reliable criteria for judging the diffraction data resolution limit and the condition I/σ(I) = 2.0 is reasonable. However, extending the limit by about 0.2 Å beyond the resolution defined by this threshold does not deteriorate the quality of refined structures and in some cases may be beneficial. Four data sets were processed at resolutions significantly exceeding the criteria traditionally used for estimating the diffraction data resolution limit. The analysis of these data and the corresponding model-quality indicators suggests that the criteria ofmore » resolution limits widely adopted in the past may be somewhat conservative. Various parameters, such as R{sub merge} and I/σ(I), optical resolution and the correlation coefficients CC{sub 1/2} and CC*, can be used for judging the internal data quality, whereas the reliability factors R and R{sub free} as well as the maximum-likelihood target values and real-space map correlation coefficients can be used to estimate the agreement between the data and the refined model. However, none of these criteria provide a reliable estimate of the data resolution cutoff limit. The analysis suggests that extension of the maximum resolution by about 0.2 Å beyond the currently adopted limit where the I/σ(I) value drops to 2.0 does not degrade the quality of the refined structural models, but may sometimes be advantageous. Such an extension may be particularly beneficial for significantly anisotropic diffraction. Extension of the maximum resolution at the stage of data collection and structure refinement is cheap in terms of the required effort and is definitely more advisable than accepting a too conservative resolution cutoff, which is unfortunately quite frequent among the crystal structures deposited in the Protein Data Bank.« less

Experimental verification of orbital engineering at the atomic scale: Charge transfer and symmetry breaking in nickelate heterostructures

NASA Astrophysics Data System (ADS)

Phillips, Patrick J.; Rui, Xue; Georgescu, Alexandru B.; Disa, Ankit S.; Longo, Paolo; Okunishi, Eiji; Walker, Fred; Ahn, Charles H.; Ismail-Beigi, Sohrab; Klie, Robert F.

2017-05-01

Epitaxial strain, layer confinement, and inversion symmetry breaking have emerged as powerful new approaches to control the electronic and atomic-scale structural properties of complex metal oxides. Trivalent rare-earth (RE) nickelate R E NiO3 heterostructures have been shown to be exemplars since the orbital occupancy, degeneracy, and, consequently, electronic/magnetic properties can be altered as a function of epitaxial strain, layer thickness, and superlattice structure. One recent example is the tricomponent LaTiO3-LaNiO3-LaAlO3 superlattice which exhibits charge transfer and orbital polarization as the result of its interfacial dipole electric field. A crucial step towards control of these parameters for future electronic and magnetic device applications is to develop an understanding of both the magnitude and range of the octahedral network's response towards interfacial strain and electric fields. An approach that provides atomic-scale resolution and sensitivity towards the local octahedral distortions and orbital occupancy is therefore required. Here, we employ atomic-resolution imaging coupled with electron spectroscopies and first-principles theory to examine the role of interfacial charge transfer and symmetry breaking in a tricomponent nickelate superlattice system. We find that nearly complete charge transfer occurs between the LaTiO3 and LaNiO3 layers, resulting in a mixed Ni2 +/Ni3 + valence state. We further demonstrate that this charge transfer is highly localized with a range of about 1 unit cell within the LaNiO3 layers. We also show how Wannier-function-based electron counting provides a simple physical picture of the electron distribution that connects directly with formal valence charges. The results presented here provide important feedback to synthesis efforts aimed at stabilizing new electronic phases that are not accessible by conventional bulk or epitaxial film approaches.

Resolution experiments using the white light speckle method.

PubMed

Conley, E; Cloud, G

1991-03-01

Noncoherent light speckle methods have been successfully applied to gauge the motion of glaciers and buildings. Resolution of the optical method was limited by the aberrating turbulent atmosphere through which the images were collected. Sensitivity limitations regarding this particular application of speckle interferometry are discussed and analyzed. Resolution limit experiments that were incidental to glacier flow studies are related to the basic theory of astronomical imaging. Optical resolution of the ice flow measurement technique is shown to be in substantial agreement with the sensitivity predictions of astronomy theory.

Short-crested waves in the surf zone

NASA Astrophysics Data System (ADS)

Wei, Zhangping; Dalrymple, Robert A.; Xu, Munan; Garnier, Roland; Derakhti, Morteza

2017-05-01

This study investigates short-crested waves in the surf zone by using the mesh-free Smoothed Particle Hydrodynamics model, GPUSPH. The short-crested waves are created by generating intersecting wave trains in a numerical wave basin with a beach. We first validate the numerical model for short-crested waves by comparison with large-scale laboratory measurements. Then short-crested wave breaking over a planar beach is studied comprehensively. We observe rip currents as discussed in Dalrymple (1975) and undertow created by synchronous intersecting waves. The wave breaking of the short-crested wavefield created by the nonlinear superposition of intersecting waves and wave-current interaction result in the formation of isolated breakers at the ends of breaking wave crests. Wave amplitude diffraction at these isolated breakers gives rise to an increase in the alongshore wave number in the inner surf zone. Moreover, 3-D vortices and multiple circulation cells with a rotation frequency much lower than the incident wave frequency are observed across the outer surf zone to the beach. Finally, we investigate vertical vorticity generation under short-crested wave breaking and find that breaking of short-crested waves generates vorticity as pointed out by Peregrine (1998). Vorticity generation is not only observed under short-crested waves with a limited number of wave components but also under directional wave spectra.

Numerical Simulation of a Seaway with Breaking

NASA Astrophysics Data System (ADS)

Dommermuth, Douglas; O'Shea, Thomas; Brucker, Kyle; Wyatt, Donald

2012-11-01

The focus of this presentation is to describe the recent efforts to simulate a fully non-linear seaway with breaking by using a high-order spectral (HOS) solution of the free-surface boundary value problem to drive a three-dimensional Volume of Fluid (VOF) solution. Historically, the two main types of simulations to simulate free-surface flows are the boundary integral equations method (BIEM) and high-order spectral (HOS) methods. BIEM calculations fail at the point at which the surface impacts upon itself, if not sooner, and HOS methods can only simulate a single valued free-surface. Both also employ a single-phase approximation in which the effects of the air on the water are neglected. Due to these limitations they are unable to simulate breaking waves and air entrainment. The Volume of Fluid (VOF) method on the other hand is suitable for modeling breaking waves and air entrainment. However it is computationally intractable to generate a realistic non-linear sea-state. Here, we use the HOS solution to quickly drive, or nudge, the VOF solution into a non-linear state. The computational strategies, mathematical formulation, and numerical implementation will be discussed. The results of the VOF simulation of a seaway with breaking will also be presented, and compared to the single phase, single valued HOS results.

Sgoldstino-less inflation and low energy SUSY breaking

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

Argurio, Riccardo; Coone, Dries; Mariotti, Alberto

2017-07-01

We assess the range of validity of sgoldstino-less inflation in a scenario of low energy supersymmetry breaking. We first analyze the consistency conditions that an effective theory of the inflaton and goldstino superfields should satisfy in order to be faithfully described by a sgoldstino-less model. Enlarging the scope of previous studies, we investigate the case where the effective field theory cut-off, and hence also the sgoldstino mass, are inflaton-dependent. We then introduce a UV complete model where one can realize successfully sgoldstino-less inflation and gauge mediation of supersymmetry breaking, combining the α-attractor mechanism and a weakly coupled model of spontaneousmore » breaking of supersymmetry. In this class of models we find that, given current limits on superpartner masses, the gravitino mass has a lower bound of the order of the MeV, i.e. we cannot reach very low supersymmetry breaking scales. On the plus side, we recognize that in this framework, one can derive the complete superpartner spectrum as well as compute inflation observables, the reheating temperature, and address the gravitino overabundance problem. We then show that further constraints come from collider results and inflation observables. Their non trivial interplay seems a staple feature of phenomenological studies of supersymmetric inflationary models.« less

Adaptation of the TdT assay for semi-quantitative flow cytometric detection of DNA strand breaks

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

Bromidge, T.J.; Howe, D.J.; Johnson, S.A.

The enzyme Terminal Deoxynucleotidyl Transferase (TdT) is a DNA polymerase which can be used to label DNA strand breaks by the incorporation of a labelled nucleotide followed by a fluorescent detection step. The amount of label incorporated can then be assessed by flow cytometry. The mechanism of action of TdT, however, will allow the addition of varying numbers of nucleotides to the free 3{prime} termini produced by DNA strand breaks. The substitution of Digoxigenin (DIG){trademark} labelled dideoxynucleotides for labelled deoxy-nucleotides in the TdT assay will limit the addition of label to a DNA break to a single nucleotide, thus ensuringmore » a direct relationship between an increase in DNA strand breaks and an increase in fluorescence. We have used this adaptation of the TdT assay to evaluate DNA damage incurred in lymphocytes, from patients with Chronic Lymphocytic Leukemia (CLL), on exposure to UV irradiation and apoptosis-inducing drugs, fludarabine and 2-Chloro-2{prime}-deoxyadenosine (2-CdA). This technique may give a good indication of the susceptibility of CLL patients to apoptosis inducing drugs, and hence an indication of the likely response to these therapies. 7 refs., 2 figs., 2 tabs.« less

A variable ULX and possible IMBH candidate in M51a

NASA Astrophysics Data System (ADS)

Earnshaw, Hannah M.; Roberts, Timothy P.; Heil, Lucy M.; Mezcua, Mar; Walton, Dominic J.; Done, Chris; Harrison, Fiona A.; Lansbury, George B.; Middleton, Matthew J.; Sutton, Andrew D.

2016-03-01

Ultraluminous X-ray source (ULX)-7, in the northern spiral arm of M51, demonstrates unusual behaviour for an ULX, with a hard X-ray spectrum but very high short-term variability. This suggests that it is not in a typical ultraluminous state. We analyse the source using archival data from XMM-Newton, Chandra and NuSTAR, and by examining optical and radio data from HST and Very Large Array. Our X-ray spectral analysis shows that the source has a hard power-law spectral shape with a photon index Γ ˜ 1.5, which persists despite the source's X-ray luminosity varying by over an order of magnitude. The power spectrum of the source features a break at 6.5^{+0.5}_{-1.1} × 10-3 Hz, from a low-frequency spectral index of α _1={-}0.1^{+0.5}_{-0.2} to a high-frequency spectral index of α _2=6.5^{+0.05}_{-0.14}, making it analogous to the low-frequency break found in the power spectra of low/hard state black holes (BHs). We can take a lower frequency limit for a corresponding high-frequency break to calculate a BH mass upper limit of 1.6 × 103 M⊙. Using the X-ray/radio Fundamental Plane, we calculate another upper limit to the BH mass of 3.5 × 104 M⊙ for a BH in the low/hard state. The hard spectrum, high rms variability and mass limits are consistent with ULX-7 being an intermediate-mass BH; however we cannot exclude other interpretations of this source's interesting behaviour, most notably a neutron star with an extreme accretion rate.

High-volume manufacturing compatible dry development rinse process (DDRP): patterning and defectivity performance for EUVL

NASA Astrophysics Data System (ADS)

Sayan, Safak; Vanelderen, Pieter; Hetel, Iulian; Chan, BT; Raghavan, Praveen; Blanco, Victor; Foubert, Philippe; D'urzo, Lucia; De Simone, Danilo; Vandenberghe, Geert

2017-04-01

There are many knobs available that change the chemical and physical properties of the photoresists to "break" the RLS (Resolution, Sensitivity, Line edge/width roughness) trade-off, however those are not enough today to realize a material to satisfy all requirements at once for 7nm technology and beyond. DDRP improves the ultimate achievable resolution via pattern collapse mitigation, hence the priority of requirements for the EUV photoresist development may be changed with more focus on Sensitivity and LWR. This may potentially provide a new conceptual approach towards EUV PR development for DDRP applications. We have previously demonstrated pattern collapse (PC) mitigation via DDRP on different EUVL photoresists (including different resist platforms), achieving ultimate resolution and exposure latitude improvements [1,2]. In this contribution, we report patterning and material defect performance of HVM compatible (all aqueous) dry development rinse material. We will also report on process window improvement on 2-dimensional metal structures towards standard cell size reduction with elimination of mask layer(s) using single EUV exposure.

Investigation of TiN thin film oxidation depending on the substrate temperature at vacuum break

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

Piallat, Fabien, E-mail: fabien.piallat@gmail.com; CEA, LETI, Campus Minatec, F-38054 Grenoble; LTM-CNRS, 17 rue des Martyrs, 38054 Grenoble

2016-09-15

Due to the reduction of the thickness of the layers used in the advanced technology nodes, there is a growing importance of the surface phenomena in the definition of the general properties of the materials. One of the least controlled and understood phenomenon is the oxidation of metals after deposition, at the vacuum break. In this study, the influence of the sample temperature at vacuum break on the oxidation level of TiN deposited by metalorganic chemical vapor deposition is investigated. TiN resistivity appears to be lower for samples which underwent vacuum break at high temperature. Using X-ray photoelectron spectrometry analysis,more » this change is correlated to the higher oxidation of the TiN layer. Moreover, angle resolved XPS analysis reveals that higher is the temperature at the vacuum break, higher is the surface oxidation of the sample. This surface oxidation is in turn limiting the diffusion of oxygen in the volume of the layer. Additionally, evolution of TiN layers resistivity was monitored in time and it shows that resistivity increases until a plateau is reached after about 10 days, with the lowest temperature at vacuum break resulting in the highest increase, i.e., the resistivity of the sample released to atmosphere at high temperature increased by a factor 1.7 whereas the resistivity of the sample cooled down under vacuum temperature increased by a factor 2.7.« less

Diffraction-Limited Plenoptic Imaging with Correlated Light

NASA Astrophysics Data System (ADS)

Pepe, Francesco V.; Di Lena, Francesco; Mazzilli, Aldo; Edrei, Eitan; Garuccio, Augusto; Scarcelli, Giuliano; D'Angelo, Milena

2017-12-01

Traditional optical imaging faces an unavoidable trade-off between resolution and depth of field (DOF). To increase resolution, high numerical apertures (NAs) are needed, but the associated large angular uncertainty results in a limited range of depths that can be put in sharp focus. Plenoptic imaging was introduced a few years ago to remedy this trade-off. To this aim, plenoptic imaging reconstructs the path of light rays from the lens to the sensor. However, the improvement offered by standard plenoptic imaging is practical and not fundamental: The increased DOF leads to a proportional reduction of the resolution well above the diffraction limit imposed by the lens NA. In this Letter, we demonstrate that correlation measurements enable pushing plenoptic imaging to its fundamental limits of both resolution and DOF. Namely, we demonstrate maintaining the imaging resolution at the diffraction limit while increasing the depth of field by a factor of 7. Our results represent the theoretical and experimental basis for the effective development of promising applications of plenoptic imaging.

Diffraction-Limited Plenoptic Imaging with Correlated Light.

PubMed

Pepe, Francesco V; Di Lena, Francesco; Mazzilli, Aldo; Edrei, Eitan; Garuccio, Augusto; Scarcelli, Giuliano; D'Angelo, Milena

2017-12-15

Traditional optical imaging faces an unavoidable trade-off between resolution and depth of field (DOF). To increase resolution, high numerical apertures (NAs) are needed, but the associated large angular uncertainty results in a limited range of depths that can be put in sharp focus. Plenoptic imaging was introduced a few years ago to remedy this trade-off. To this aim, plenoptic imaging reconstructs the path of light rays from the lens to the sensor. However, the improvement offered by standard plenoptic imaging is practical and not fundamental: The increased DOF leads to a proportional reduction of the resolution well above the diffraction limit imposed by the lens NA. In this Letter, we demonstrate that correlation measurements enable pushing plenoptic imaging to its fundamental limits of both resolution and DOF. Namely, we demonstrate maintaining the imaging resolution at the diffraction limit while increasing the depth of field by a factor of 7. Our results represent the theoretical and experimental basis for the effective development of promising applications of plenoptic imaging.

Laser vibrometry in the quality control of the break of tanned leather

NASA Astrophysics Data System (ADS)

Preciado, J. Sanchez; Lopez, C. Perez; Hernandez-Montes, M. del Socorro; Torre-Ibarra, M. de la; Moreno, J. M. Flores; Ruiz, C. Tavera; Mendoza Santoyo, F.; Galan, M.

2018-05-01

Tanning industry treats hides and the skin of animals for their use in products such as clothes, furniture and car's interiors. The worth of leather is highly affected by defects that may appear prior or during the tanning process. Break, which refers to the wrinkling of the grain surface of leather, is one of the main issues because it affects not only the visual appearance of leather, but also its mechanical properties. The standardized method to classify the break pattern is done by bending the leather with the hand and comparing visually the resulting wrinkles that appear with a reference pattern, which makes the classification subjective and limits the evaluation to small areas. Laser vibrometry is an optical technique that has been applied in vibrational and modal analysis, which are methodologies used to obtain the mechanical properties of materials. This work demonstrates the use of a single-point vibrometer as a noncontact and nondestructive optical method to discriminate among five break levels, which could increase the effectiveness of leather classification for quality control in the tanning industry.

Evaluation of Structural Factors Potentially Implicated in Acute Lymphoblastic Leukemia: A report of the MIGICCL.

PubMed

López-Sánchez, Dulce María; Méndez-Tenorio, Alfonso; Roacho-Pérez, Jorge Alberto; Rangel-López, Angélica

2016-10-01

Acute lymphoblastic leukemia (ALL) is the most common cancer in the pediatric population; ∼80% of the cases show some translocation. Translocations that result in ALL are due to chromosome breaks. However, the exact mechanisms that cause these breaks have not been well studied. A detailed search of the breakpoints associated with ALL reported in the NCBI database shows that some are concentrated in limited regions of the chromosome, whereas others are scattered throughout. Therefore, the objective of this study was to identify the structural factors involved in chromosomal breaks in ALL. We performed several bioinformatic studies on the sequences where chromosomal breakpoints have been reported in search of rearrangements: areas of high similarity, thermodynamic stability, composition and conformation of the DNA. Certain factors may influence chromosome breaks and are capable of predicting the propensity towards these types of events. These findings may be useful in the design of molecular techniques able to detect these changes in ALL. Copyright © 2016 IMSS. Published by Elsevier Inc. All rights reserved.

Subangstrom resolution X-ray structure details aquaporin-water interactions.

PubMed

Eriksson, Urszula Kosinska; Fischer, Gerhard; Friemann, Rosmarie; Enkavi, Giray; Tajkhorshid, Emad; Neutze, Richard

2013-06-14

Aquaporins are membrane channels that facilitate the flow of water across biological membranes. Two conserved regions are central for selective function: the dual asparagine-proline-alanine (NPA) aquaporin signature motif and the aromatic and arginine selectivity filter (SF). Here, we present the crystal structure of a yeast aquaporin at 0.88 angstrom resolution. We visualize the H-bond donor interactions of the NPA motif's asparagine residues to passing water molecules; observe a polarized water-water H-bond configuration within the channel; assign the tautomeric states of the SF histidine and arginine residues; and observe four SF water positions too closely spaced to be simultaneously occupied. Strongly correlated movements break the connectivity of SF waters to other water molecules within the channel and prevent proton transport via a Grotthuss mechanism.

Active chiral control of GHz acoustic whispering-gallery modes

NASA Astrophysics Data System (ADS)

Mezil, Sylvain; Fujita, Kentaro; Otsuka, Paul H.; Tomoda, Motonobu; Clark, Matt; Wright, Oliver B.; Matsuda, Osamu

2017-10-01

We selectively generate chiral surface-acoustic whispering-gallery modes in the gigahertz range on a microscopic disk by means of an ultrafast time-domain technique incorporating a spatial light modulator. Active chiral control is achieved by making use of an optical pump spatial profile in the form of a semicircular arc, positioned on the sample to break the symmetry of clockwise- and counterclockwise-propagating modes. Spatiotemporal Fourier transforms of the interferometrically monitored two-dimensional acoustic fields measured to micron resolution allow individual chiral modes and their azimuthal mode order, both positive and negative, to be distinguished. In particular, for modes with 15-fold rotational symmetry, we demonstrate ultrafast chiral control of surface acoustic waves in a micro-acoustic system with picosecond temporal resolution. Applications include nondestructive testing and surface acoustic wave devices.

Restricted Spectral Accuracy Analysis to Identify the Single Correct Organic Compound Elemental-Composition from Orbitrap Accurate Mass Data Lists Obtained at Very High Resolution.

PubMed

Strife, Robert J; Wang, Yongdong; Kuehl, Don

2018-06-19

Restricted Spectral Accuracy (RSA) is applied to Orbitrap data (240,000 resolution at m/z 400) to more clearly break out the scoring and ranking of allowable elemental compositions (EC) in a candidate list. The correct EC is usually top ranked and separated from other answers by 10-40% within the dimensionless 0-100% scale, providing a single, definitive EC. The A+2 position (where A denotes the monoisotopic line position) is especially advantageous in RSA. It has enough intensity and more complexity than (A+1) fine lines and is like a fingerprint. Avoidance of coalescene phenomena and careful ion population control are essential. This article is protected by copyright. All rights reserved.

Parity breaking signatures from a Chern-Simons coupling during inflation: the case of non-Gaussian gravitational waves

NASA Astrophysics Data System (ADS)

Bartolo, Nicola; Orlando, Giorgio

2017-07-01

Considering high-energy modifications of Einstein gravity during inflation is an interesting issue. We can constrain the strength of the new gravitational terms through observations of inflationary imprints in the actual universe. In this paper we analyze the effects on slow-roll models due to a Chern-Simons term coupled to the inflaton field through a generic coupling function f(phi). A well known result is the polarization of primordial gravitational waves (PGW) into left and right eigenstates, as a consequence of parity breaking. In such a scenario the modifications to the power spectrum of PGW are suppressed under the conditions that allow to avoid the production of ghost gravitons at a certain energy scale, the so-called Chern-Simons mass MCS. In general it has been recently pointed out that there is very little hope to efficiently constrain chirality of PGW on the basis solely of two-point statistics from future CMB data, even in the most optimistic cases. Thus we search if significant parity breaking signatures can arise at least in the bispectrum statistics. We find that the tensor-tensor-scalar bispectra langle γ γ ζ rangle for each polarization state are the only ones that are not suppressed. Their amplitude, setting the level of parity breaking during inflation, is proportional to the second derivative of the coupling function f(phi) and they turn out to be maximum in the squeezed limit. We comment on the squeezed-limit consistency relation arising in the case of chiral gravitational waves, and on possible observables to constrain these signatures.

Retrograde accretion of a Caribbean fringing reef controlled by hurricanes and sea-level rise

NASA Astrophysics Data System (ADS)

Blanchon, Paul; Richards, Simon; Bernal, Juan Pablo; Cerdeira-Estrada, Sergio; Ibarra, M. Socrates; Corona-Martínez, Liliana; Martell-Dubois, Raúl

2017-10-01

Predicting the impact of sea-level (SL) rise on coral reefs requires reliable models of reef accretion. Most assume that accretion results from vertical growth of coralgal framework, but recent studies show that reefs exposed to hurricanes consist of layers of coral gravel rather than in-place corals. New models are therefore needed to account for hurricane impact on reef accretion over geological timescales. To investigate this geological impact, we report the configuration and development of a 4-km-long fringing reef at Punta Maroma along the northeast Yucatan Peninsula. Satellite-derived bathymetry shows the crest is set-back a uniform distance of 315 ±15 m from a mid-shelf slope break, and the reef-front decreases 50% in width and depth along its length. A 12-core drill transect constrained by multiple 230Th ages shows the reef is composed of an 2-m thick layer of coral clasts that has retrograded 100 m over its back-reef during the last 5.5 ka. These findings are consistent with a hurricane-control model of reef development where large waves trip and break over the mid-shelf slope break, triggering rapid energy dissipation and thus limiting how far upslope individual waves can fragment corals and redistribute clasts. As SL rises and water depth increases, energy dissipation during wave-breaking is reduced, extending the clast-transport limit, thus leading to reef retrogradation. This hurricane model may be applicable to a large sub-set of fringing reefs in the tropical Western-Atlantic necessitating a reappraisal of their accretion rates and response to future SL rise.

Activation induced deaminase C-terminal domain links DNA breaks to end protection and repair during class switch recombination

PubMed Central

Zahn, Astrid; Eranki, Anil K.; Patenaude, Anne-Marie; Methot, Stephen P.; Fifield, Heather; Cortizas, Elena M.; Foster, Paul; Imai, Kohsuke; Durandy, Anne; Larijani, Mani; Verdun, Ramiro E.; Di Noia, Javier M.

2014-01-01

Activation-induced deaminase (AID) triggers antibody class switch recombination (CSR) in B cells by initiating DNA double strand breaks that are repaired by nonhomologous end-joining pathways. A role for AID at the repair step is unclear. We show that specific inactivation of the C-terminal AID domain encoded by exon 5 (E5) allows very efficient deamination of the AID target regions but greatly impacts the efficiency and quality of subsequent DNA repair. Specifically eliminating E5 not only precludes CSR but also, causes an atypical, enzymatic activity-dependent dominant-negative effect on CSR. Moreover, the E5 domain is required for the formation of AID-dependent Igh-cMyc chromosomal translocations. DNA breaks at the Igh switch regions induced by AID lacking E5 display defective end joining, failing to recruit DNA damage response factors and undergoing extensive end resection. These defects lead to nonproductive resolutions, such as rearrangements and homologous recombination that can antagonize CSR. Our results can explain the autosomal dominant inheritance of AID variants with truncated E5 in patients with hyper-IgM syndrome 2 and establish that AID, through the E5 domain, provides a link between DNA damage and repair during CSR. PMID:24591601

Limited Area Coverage/High Resolution Picture Transmission (LAC/HRPT) data vegetative index calculation processor user's manual

NASA Technical Reports Server (NTRS)

Obrien, S. O. (Principal Investigator)

1980-01-01

The program, LACVIN, calculates vegetative indexes numbers on limited area coverage/high resolution picture transmission data for selected IJ grid sections. The IJ grid sections were previously extracted from the full resolution data tapes and stored on disk files.

Exploring non-holomorphic soft terms in the framework of gauge mediated supersymmetry breaking

NASA Astrophysics Data System (ADS)

Chattopadhyay, Utpal; Das, Debottam; Mukherjee, Samadrita

2018-01-01

It is known that in the absence of a gauge singlet field, a specific class of supersymmetry (SUSY) breaking non-holomorphic (NH) terms can be soft breaking in nature so that they may be considered along with the Minimal Supersymmetric Standard Model (MSSM) and beyond. There have been studies related to these terms in minimal supergravity based models. Consideration of an F-type SUSY breaking scenario in the hidden sector with two chiral superfields however showed Planck scale suppression of such terms. In an unbiased point of view for the sources of SUSY breaking, the NH terms in a phenomenological MSSM (pMSSM) type of analysis showed a possibility of a large SUSY contribution to muon g - 2, a reasonable amount of corrections to the Higgs boson mass and a drastic reduction of the electroweak fine-tuning for a higgsino dominated {\\tilde{χ}}_1^0 in some regions of parameter space. We first investigate here the effects of the NH terms in a low scale SUSY breaking scenario. In our analysis with minimal gauge mediated supersymmetry breaking (mGMSB) we probe how far the results can be compared with the previous pMSSM plus NH terms based study. We particularly analyze the Higgs, stop and the electroweakino sectors focusing on a higgsino dominated {\\tilde{χ}}_1^0 and {\\tilde{χ}}_1^{± } , a feature typically different from what appears in mGMSB. The effect of a limited degree of RG evolutions and vanishing of the trilinear coupling terms at the messenger scale can be overcome by choosing a non-minimal GMSB scenario, such as one with a matter-messenger interaction.

Proving and Improving Wave Models in the Arctic Ocean and its MIZ

DTIC Science & Technology

2015-09-30

in the central Arctic Ocean (Hunkins, 1966); in the Antarctic MIZ, Weddell Sea, slightly larger values were reported ranging from 1.6 × 10-2 m2 s-1...unprecedented spatial resolution. Such vast fields of pancake ice have traditionally only been associated with the advancing Antarctic MIZ, and, on a smaller...achieved in an MIZ dominated by large waves. Data on the break-up of a large tabular iceberg by swell, measured in Baffin Bay, were published

Super-resolution optical microscopy for studying membrane structure and dynamics.

PubMed

Sezgin, Erdinc

2017-07-12

Investigation of cell membrane structure and dynamics requires high spatial and temporal resolution. The spatial resolution of conventional light microscopy is limited due to the diffraction of light. However, recent developments in microscopy enabled us to access the nano-scale regime spatially, thus to elucidate the nanoscopic structures in the cellular membranes. In this review, we will explain the resolution limit, address the working principles of the most commonly used super-resolution microscopy techniques and summarise their recent applications in the biomembrane field.

Scaling properties of Polish rain series

NASA Astrophysics Data System (ADS)

Licznar, P.

2009-04-01

Scaling properties as well as multifractal nature of precipitation time series have not been studied for local Polish conditions until recently due to lack of long series of high-resolution data. The first Polish study of precipitation time series scaling phenomena was made on the base of pluviograph data from the Wroclaw University of Environmental and Life Sciences meteorological station located at the south-western part of the country. The 38 annual rainfall records from years 1962-2004 were converted into digital format and transformed into a standard format of 5-minute time series. The scaling properties and multifractal character of this material were studied by means of several different techniques: power spectral density analysis, functional box-counting, probability distribution/multiple scaling and trace moment methods. The result proved the general scaling character of time series at the range of time scales ranging form 5 minutes up to at least 24 hours. At the same time some characteristic breaks at scaling behavior were recognized. It is believed that the breaks were artificial and arising from the pluviograph rain gauge measuring precision limitations. Especially strong limitations at the precision of low-intensity precipitations recording by pluviograph rain gauge were found to be the main reason for artificial break at energy spectra, as was reported by other authors before. The analysis of co-dimension and moments scaling functions showed the signs of the first-order multifractal phase transition. Such behavior is typical for dressed multifractal processes that are observed by spatial or temporal averaging on scales larger than the inner-scale of those processes. The fractal dimension of rainfall process support derived from codimension and moments scaling functions geometry analysis was found to be 0.45. The same fractal dimension estimated by means of the functional box-counting method was equal to 0.58. At the final part of the study implementation of double trace moment method allowed for estimation of local universal multifractal rainfall parameters (α=0.69; C1=0.34; H=-0.01). The research proved the fractal character of rainfall process support and multifractal character of the rainfall intensity values variability among analyzed time series. It is believed that scaling of local Wroclaw's rainfalls for timescales at the range from 24 hours up to 5 minutes opens the door for future research concerning for example random cascades implementation for daily precipitation totals disaggregation for smaller time intervals. The results of such a random cascades functioning in a form of 5 minute artificial rainfall scenarios could be of great practical usability for needs of urban hydrology, and design and hydrodynamic modeling of storm water and combined sewage conveyance systems.

Super-Resolution Microscopy Techniques and Their Potential for Applications in Radiation Biophysics.

PubMed

Eberle, Jan Philipp; Rapp, Alexander; Krufczik, Matthias; Eryilmaz, Marion; Gunkel, Manuel; Erfle, Holger; Hausmann, Michael

2017-01-01

Fluorescence microscopy is an essential tool for imaging tagged biological structures. Due to the wave nature of light, the resolution of a conventional fluorescence microscope is limited laterally to about 200 nm and axially to about 600 nm, which is often referred to as the Abbe limit. This hampers the observation of important biological structures and dynamics in the nano-scaled range ~10 nm to ~100 nm. Consequentially, various methods have been developed circumventing this limit of resolution. Super-resolution microscopy comprises several of those methods employing physical and/or chemical properties, such as optical/instrumental modifications and specific labeling of samples. In this article, we will give a brief insight into a variety of selected optical microscopy methods reaching super-resolution beyond the Abbe limit. We will survey three different concepts in connection to biological applications in radiation research without making a claim to be complete.

Mechanical limits to maximum weapon size in a giant rhinoceros beetle.

PubMed

McCullough, Erin L

2014-07-07

The horns of giant rhinoceros beetles are a classic example of the elaborate morphologies that can result from sexual selection. Theory predicts that sexual traits will evolve to be increasingly exaggerated until survival costs balance the reproductive benefits of further trait elaboration. In Trypoxylus dichotomus, long horns confer a competitive advantage to males, yet previous studies have found that they do not incur survival costs. It is therefore unlikely that horn size is limited by the theoretical cost-benefit equilibrium. However, males sometimes fight vigorously enough to break their horns, so mechanical limits may set an upper bound on horn size. Here, I tested this mechanical limit hypothesis by measuring safety factors across the full range of horn sizes. Safety factors were calculated as the ratio between the force required to break a horn and the maximum force exerted on a horn during a typical fight. I found that safety factors decrease with increasing horn length, indicating that the risk of breakage is indeed highest for the longest horns. Structural failure of oversized horns may therefore oppose the continued exaggeration of horn length driven by male-male competition and set a mechanical limit on the maximum size of rhinoceros beetle horns. © 2014 The Author(s) Published by the Royal Society. All rights reserved.

Exploring the Possibilities and Limitations of Service-Learning: A Critical Analysis of College Student Narratives about HIV/AIDS

ERIC Educational Resources Information Center

Jones, Susan Robb; LePeau, Lucy A.; Robbins, Claire K.

2013-01-01

This article reports the results of a study that explored the possibilities and limitations of service-learning by deconstructing the narratives about HIV/AIDS that emerged from five college students who participated in an alternative spring break program. Employing a critical (Rhoads, 1997) and anti-foundational (Butin, 2010) approach to inquiry,…

Best estimate plus uncertainty analysis of departure from nucleate boiling limiting case with CASL core simulator VERA-CS in response to PWR main steam line break event

DOE PAGES

Brown, Cameron S.; Zhang, Hongbin; Kucukboyaci, Vefa; ...

2016-09-07

VERA-CS (Virtual Environment for Reactor Applications, Core Simulator) is a coupled neutron transport and thermal-hydraulics subchannel code under development by the Consortium for Advanced Simulation of Light Water Reactors (CASL). VERA-CS was used to simulate a typical pressurized water reactor (PWR) full core response with 17x17 fuel assemblies for a main steam line break (MSLB) accident scenario with the most reactive rod cluster control assembly stuck out of the core. The accident scenario was initiated at the hot zero power (HZP) at the end of the first fuel cycle with return to power state points that were determined by amore » system analysis code and the most limiting state point was chosen for core analysis. The best estimate plus uncertainty (BEPU) analysis method was applied using Wilks’ nonparametric statistical approach. In this way, 59 full core simulations were performed to provide the minimum departure from nucleate boiling ratio (MDNBR) at the 95/95 (95% probability with 95% confidence level) tolerance limit. The results show that this typical PWR core remains within MDNBR safety limits for the MSLB accident.« less

Best estimate plus uncertainty analysis of departure from nucleate boiling limiting case with CASL core simulator VERA-CS in response to PWR main steam line break event

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

Brown, Cameron S.; Zhang, Hongbin; Kucukboyaci, Vefa

VERA-CS (Virtual Environment for Reactor Applications, Core Simulator) is a coupled neutron transport and thermal-hydraulics subchannel code under development by the Consortium for Advanced Simulation of Light Water Reactors (CASL). VERA-CS was used to simulate a typical pressurized water reactor (PWR) full core response with 17x17 fuel assemblies for a main steam line break (MSLB) accident scenario with the most reactive rod cluster control assembly stuck out of the core. The accident scenario was initiated at the hot zero power (HZP) at the end of the first fuel cycle with return to power state points that were determined by amore » system analysis code and the most limiting state point was chosen for core analysis. The best estimate plus uncertainty (BEPU) analysis method was applied using Wilks’ nonparametric statistical approach. In this way, 59 full core simulations were performed to provide the minimum departure from nucleate boiling ratio (MDNBR) at the 95/95 (95% probability with 95% confidence level) tolerance limit. The results show that this typical PWR core remains within MDNBR safety limits for the MSLB accident.« less

Limit on possible narrow rings around Jupiter

NASA Technical Reports Server (NTRS)

Dunham, E.; Elliot, J. L.; Mink, D.; Klemola, A. R.

1982-01-01

An upper limit to the optical depth of the Jovian ring at high spatial resolution, determined from stellar occultation data, is reported. The spatial resolution of the observation is limited to about 13 km in Jupiter's equatorial plane by the projection of the Fresnel zone on the equatorial plane in the radial direction. At this resolution, the normal optical depth limit is about 0.008. This limit applies to a strip in the Jovian equatorial plane that crosses the orbits of Amalthea, 1979J1, 1979J3, and the ring. An upper limit on the number density of kilometer-size boulders has been set at one per 11.000 sq km in the equatorial plane.

Breaking Kelvin-Helmholtz waves and cloud-top entrainment as revealed by K-band Doppler radar

NASA Technical Reports Server (NTRS)

Martner, Brooks E.; Ralph, F. Martin

1993-01-01

Radars have occasionally detected breaking Kelvin-Helmholtz (KH) waves under clear-air conditions in the atmospheric boundary layer and in the free troposphere. However, very few direct measurements of such waves within clouds have previously been reported and those have not clearly documented wave breaking. In this article, we present some of the most detailed and striking radar observations to date of breaking KH waves within clouds and at cloud top and discuss their relevance to the issue of cloud-top entrainment, which is believed to be important in convective and stratiform clouds. Aircraft observations reported by Stith suggest that vortex-like circulations near cloud top are an entrainment mechanism in cumuliform clouds. Laboratory and modeling studies have examined possibility that KH instability may be responsible for mixing at cloud top, but direct observations have not yet been presented. Preliminary analyses shown here may help fill this gap. The data presented in this paper were obtained during two field projects in 1991 that included observations from the NOAA Wave Propagation Laboratory's K-band Doppler radar (wavelength = 8.7 mm) and special rawinsonde ascents. The sensitivity (-30 dBZ at 10 km range), fine spatial resolution (375-m pulse length and 0.5 degrees beamwidth), velocity measurement precision (5-10 cm s-1), scanning capability, and relative immunity to ground clutter make it sensitive to non-precipitating and weakly precipitating clouds, and make it an excellent instrument to study gravity waves in clouds. In particular, the narrow beam width and short pulse length create scattering volumes that are cylinders 37.5 m long and 45 m (90 m) in diameter at 5 km (10 km) range. These characteristics allow the radar to resolve the detailed structure in breaking KH waves such as have been seen in photographic cloud images.

Super-resolution microscopy reveals protein spatial reorganization in early innate immune responses.

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

Carson, Bryan D.; Aaron, Jesse S.; Timlin, Jerilyn Ann

2010-10-01

Over the past decade optical approaches were introduced that effectively break the diffraction barrier. Of particular note were introductions of Stimulated Emission/Depletion (STED) microscopy, Photo-Activated Localization Microscopy (PALM), and the closely related Stochastic Optical Reconstruction Microscopy (STORM). STORM represents an attractive method for researchers, as it does not require highly specialized optical setups, can be implemented using commercially available dyes, and is more easily amenable to multicolor imaging. We implemented a simultaneous dual-color, direct-STORM imaging system through the use of an objective-based TIRF microscope and filter-based image splitter. This system allows for excitation and detection of two fluorophors simultaneously, viamore » projection of each fluorophor's signal onto separate regions of a detector. We imaged the sub-resolution organization of the TLR4 receptor, a key mediator of innate immune response, after challenge with lipopolysaccharide (LPS), a bacteria-specific antigen. While distinct forms of LPS have evolved among various bacteria, only some LPS variations (such as that derived from E. coli) typically result in significant cellular immune response. Others (such as from the plague bacteria Y. pestis) do not, despite affinity to TLR4. We will show that challenge with LPS antigens produces a statistically significant increase in TLR4 receptor clusters on the cell membrane, presumably due to recruitment of receptors to lipid rafts. These changes, however, are only detectable below the diffraction limit and are not evident using conventional imaging methods. Furthermore, we will compare the spatiotemporal behavior of TLR4 receptors in response to different LPS chemotypes in order to elucidate possible routes by which pathogens such as Y. pestis are able to circumvent the innate immune system. Finally, we will exploit the dual-color STORM capabilities to simultaneously image LPS and TLR4 receptors in the cellular membrane at resolutions at or below 40nm.« less

Analyses of GIMMS NDVI Time Series in Kogi State, Nigeria

NASA Astrophysics Data System (ADS)

Palka, Jessica; Wessollek, Christine; Karrasch, Pierre

2017-10-01

The value of remote sensing data is particularly evident where an areal monitoring is needed to provide information on the earth's surface development. The use of temporal high resolution time series data allows for detecting short-term changes. In Kogi State in Nigeria different vegetation types can be found. As the major population in this region is living in rural communities with crop farming the existing vegetation is slowly being altered. The expansion of agricultural land causes loss of natural vegetation, especially in the regions close to the rivers which are suitable for crop production. With regard to these facts, two questions can be dealt with covering different aspects of the development of vegetation in the Kogi state, the determination and evaluation of the general development of the vegetation in the study area (trend estimation) and analyses on a short-term behavior of vegetation conditions, which can provide information about seasonal effects in vegetation development. For this purpose, the GIMMS-NDVI data set, provided by the NOAA, provides information on the normalized difference vegetation index (NDVI) in a geometric resolution of approx. 8 km. The temporal resolution of 15 days allows the already described analyses. For the presented analysis data for the period 1981-2012 (31 years) were used. The implemented workflow mainly applies methods of time series analysis. The results show that in addition to the classical seasonal development, artefacts of different vegetation periods (several NDVI maxima) can be found in the data. The trend component of the time series shows a consistently positive development in the entire study area considering the full investigation period of 31 years. However, the results also show that this development has not been continuous and a simple linear modeling of the NDVI increase is only possible to a limited extent. For this reason, the trend modeling was extended by procedures for detecting structural breaks in the time series.

THE HIGH-ENERGY, ARCMINUTE-SCALE GALACTIC CENTER GAMMA-RAY SOURCE

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

Chernyakova, M.; Malyshev, D.; Aharonian, F. A.

2011-01-10

Employing data collected during the first 25 months of observations by the Fermi-LAT, we describe and subsequently seek to model the very high energy (>300 MeV) emission from the central few parsecs of our Galaxy. We analyze the morphological, spectral, and temporal characteristics of the central source, 1FGL J1745.6-2900. The data show a clear, statistically significant signal at energies above 10 GeV, where the Fermi-LAT has angular resolution comparable to that of HESS at TeV energies. This makes a meaningful joint analysis of the data possible. Our analysis of the Fermi data (alone) does not uncover any statistically significant variabilitymore » of 1FGL J1745.6-2900 at GeV energies on the month timescale. Using the combination of Fermi data on 1FGL J1745.6-2900 and HESS data on the coincident, TeV source HESS J1745-290, we show that the spectrum of the central gamma-ray source is inflected with a relatively steep spectral region matching between the flatter spectrum found at both low and high energies. We model the gamma-ray production in the inner 10 pc of the Galaxy and examine cosmic ray (CR) proton propagation scenarios that reproduce the observed spectrum of the central source. We show that a model that instantiates a transition from diffusive propagation of the CR protons at low energy to almost rectilinear propagation at high energies can explain well the spectral phenomenology. We find considerable degeneracy between different parameter choices which will only be broken with the addition of morphological information that gamma-ray telescopes cannot deliver given current angular resolution limits. We argue that a future analysis performed in combination with higher-resolution radio continuum data holds out the promise of breaking this degeneracy.« less

Spectroscopic Factors From the Single Neutron Pickup Reaction ^64Zn(d,t)

NASA Astrophysics Data System (ADS)

Leach, Kyle; Garrett, P. E.; Demand, G. A.; Finlay, P.; Green, K. L.; Phillips, A. A.; Sumithrarachchi, C. S.; Svensson, C. E.; Triambak, S.; Ball, G. C.; Faestermann, T.; Krücken, R.; Wirth, H.-F.; Herten-Berger, R.

2008-10-01

A great deal of attention has recently been paid towards high precision superallowed β-decay Ft values. With the availability of extremely high precision (<0.1%) experimental data, the precision on Ft is now limited by the ˜1% theoretical corrections.ootnotetextI.S. Towner and J.C. Hardy, Phys. Rev. C 77, 025501 (2008). This limitation is most evident in heavier superallowed nuclei (e.g. ^62Ga) where the isospin-symmetry-breaking correction calculations become more difficult due to the truncated model space. Experimental data is needed to help constrain input parameters for these calculations, and thus experimental spectroscopic factors for these nuclei are important. Preliminary results from the single-nucleon-transfer reaction ^64Zn(d,t)^63Zn will be presented, and the implications for calculations of isospin-symmetry breaking in the superallowed &+circ; decay of ^62Ga will be discussed.

Transition from homogeneous to inhomogeneous limit cycles: Effect of local filtering in coupled oscillators

NASA Astrophysics Data System (ADS)

Banerjee, Tanmoy; Biswas, Debabrata; Ghosh, Debarati; Bandyopadhyay, Biswabibek; Kurths, Jürgen

2018-04-01

We report an interesting symmetry-breaking transition in coupled identical oscillators, namely, the continuous transition from homogeneous to inhomogeneous limit cycle oscillations. The observed transition is the oscillatory analog of the Turing-type symmetry-breaking transition from amplitude death (i.e., stable homogeneous steady state) to oscillation death (i.e., stable inhomogeneous steady state). This novel transition occurs in the parametric zone of occurrence of rhythmogenesis and oscillation death as a consequence of the presence of local filtering in the coupling path. We consider paradigmatic oscillators, such as Stuart-Landau and van der Pol oscillators, under mean-field coupling with low-pass or all-pass filtered self-feedback and through a rigorous bifurcation analysis we explore the genesis of this transition. Further, we experimentally demonstrate the observed transition, which establishes its robustness in the presence of parameter fluctuations and noise.

The massive fermion phase for the U(N) Chern-Simons gauge theory in D=3 at large N

DOE PAGES

Bardeen, William A.

2014-10-07

We explore the phase structure of fermions in the U(N) Chern-Simons Gauge theory in three dimensions using the large N limit where N is the number of colors and the fermions are taken to be in the fundamental representation of the U(N) gauge group. In the large N limit, the theory retains its classical conformal behavior and considerable attention has been paid to possible AdS/CFT dualities of the theory in the conformal phase. In this paper we present a solution for the massive phase of the fermion theory that is exact to the leading order of ‘t Hooft’s large Nmore » expansion. We present evidence for the spontaneous breaking of the exact scale symmetry and analyze the properties of the dilaton that appears as the Goldstone boson of scale symmetry breaking.« less

Muon tomography imaging improvement using optimized limited angle data

NASA Astrophysics Data System (ADS)

Bai, Chuanyong; Simon, Sean; Kindem, Joel; Luo, Weidong; Sossong, Michael J.; Steiger, Matthew

2014-05-01

Image resolution of muon tomography is limited by the range of zenith angles of cosmic ray muons and the flux rate at sea level. Low flux rate limits the use of advanced data rebinning and processing techniques to improve image quality. By optimizing the limited angle data, however, image resolution can be improved. To demonstrate the idea, physical data of tungsten blocks were acquired on a muon tomography system. The angular distribution and energy spectrum of muons measured on the system was also used to generate simulation data of tungsten blocks of different arrangement (geometry). The data were grouped into subsets using the zenith angle and volume images were reconstructed from the data subsets using two algorithms. One was a distributed PoCA (point of closest approach) algorithm and the other was an accelerated iterative maximal likelihood/expectation maximization (MLEM) algorithm. Image resolution was compared for different subsets. Results showed that image resolution was better in the vertical direction for subsets with greater zenith angles and better in the horizontal plane for subsets with smaller zenith angles. The overall image resolution appeared to be the compromise of that of different subsets. This work suggests that the acquired data can be grouped into different limited angle data subsets for optimized image resolution in desired directions. Use of multiple images with resolution optimized in different directions can improve overall imaging fidelity and the intended applications.

Spontaneous breaking of scale invariance in a D = 3 U(N ) model with Chern-Simons gauge fields

DOE PAGES

Bardeen, William A.; Moshe, Moshe

2014-06-18

We study spontaneous breaking of scale invariance in the large N limit of three dimensional U(N ) κ Chern-Simons theories coupled to a scalar field in the fundamental representation. When a λ 6 ( Ø † · Ø) 3 self interaction term is added to the action we find a massive phase at a certain critical value for a combination of the λ(6) and ’t Hooft’s λ = N/κ couplings. This model attracted recent attention since at finite κ it contains a singlet sector which is conjectured to be dual to Vasiliev’s higher spin gravity on AdS 4. Our papermore » concentrates on the massive phase of the 3d boundary theory. We discuss the advantage of introducing masses in the boundary theory through spontaneous breaking of scale invariance.« less

High-scale axions without isocurvature from inflationary dynamics

DOE PAGES

Kearney, John; Orlofsky, Nicholas; Pierce, Aaron

2016-05-31

Observable primordial tensor modes in the cosmic microwave background (CMB) would point to a high scale of inflation H I. If the scale of Peccei-Quinn (PQ) breaking f a is greater than H I/2π, CMB constraints on isocurvature naively rule out QCD axion dark matter. This assumes the potential of the axion is unmodified during inflation. We revisit models where inflationary dynamics modify the axion potential and discuss how isocurvature bounds can be relaxed. We find that models that rely solely on a larger PQ-breaking scale during inflation f I require either late-time dilution of the axion abundance or highlymore » super-Planckian f I that somehow does not dominate the inflationary energy density. Models that have enhanced explicit breaking of the PQ symmetry during inflation may allow f a close to the Planck scale. Lastly, avoiding disruption of inflationary dynamics provides important limits on the parameter space.« less

Stimulated Motion Suppression (STMS): a New Approach to Break the Resolution Barrier for Ion Trap Mass Spectrometry

NASA Astrophysics Data System (ADS)

Zhou, Xiaoyu; Liu, Xinwei; Chiang, Spencer; Cao, Wenbo; Li, Ming; Ouyang, Zheng

2018-05-01

Ion trap is an excellent platform to perform tandem mass spectrometry (MS/MS), but has an intrinsic drawback in resolving power. Using ion resonant ejection as an example, the resolution degradation can be largely attributed to the broadening of the resonant frequency band (RFB) between ion motion and driving alternative-current (AC). To solve this problem, stimulated motion suppression (STMS) was developed. The key idea of STMS is the use of two suppression alternative-current (SAC) signals, which both have reversed initial phases to the main AC. The SACs can block the unexpected sideband ion resonances (or ejections), therefore playing a key role in sharpening the RFB. The proof-of-concept has been demonstrated through ion trajectory simulations and validated experimentally. STMS provides a new and versatile means for the improvement of the ion trap resolution, which for a long time has reached the bottleneck through conventional methods, e.g., increasing the radio-frequency (RF) voltage and decreasing the mass scan rate. At the end, it is worth noting that the idea of STMS is very general and principally can be applied in any RF device for the purposes of high-resolution mass analysis and ion isolation.

Example-Based Super-Resolution Fluorescence Microscopy.

PubMed

Jia, Shu; Han, Boran; Kutz, J Nathan

2018-04-23

Capturing biological dynamics with high spatiotemporal resolution demands the advancement in imaging technologies. Super-resolution fluorescence microscopy offers spatial resolution surpassing the diffraction limit to resolve near-molecular-level details. While various strategies have been reported to improve the temporal resolution of super-resolution imaging, all super-resolution techniques are still fundamentally limited by the trade-off associated with the longer image acquisition time that is needed to achieve higher spatial information. Here, we demonstrated an example-based, computational method that aims to obtain super-resolution images using conventional imaging without increasing the imaging time. With a low-resolution image input, the method provides an estimate of its super-resolution image based on an example database that contains super- and low-resolution image pairs of biological structures of interest. The computational imaging of cellular microtubules agrees approximately with the experimental super-resolution STORM results. This new approach may offer potential improvements in temporal resolution for experimental super-resolution fluorescence microscopy and provide a new path for large-data aided biomedical imaging.

Defect of focus in two-line resolution with Hanning amplitude filters

NASA Astrophysics Data System (ADS)

Karunasagar, D.; Bhikshamaiah, G.; Keshavulu Goud, M.; Lacha Goud, S.

In the presence of defocusing the modified Sparrow limits of resolution for two-line objects have been investigated for a diffraction-limited coherent optical system apodized by generalized Hanning amplitude filters. These limits have been studied as a function of different parameters such as intensity ratio, the order of the filter for various amounts of apodization parameter. Results reveal that in some situations the defocusing is effective in enhancing the resolution of an optical system.

Uncovering the effective interval of resolution parameter across multiple community optimization measures

NASA Astrophysics Data System (ADS)

Li, Hui-Jia; Cheng, Qing; Mao, He-Jin; Wang, Huanian; Chen, Junhua

2017-03-01

The study of community structure is a primary focus of network analysis, which has attracted a large amount of attention. In this paper, we focus on two famous functions, i.e., the Hamiltonian function H and the modularity density measure D, and intend to uncover the effective thresholds of their corresponding resolution parameter γ without resolution limit problem. Two widely used example networks are employed, including the ring network of lumps as well as the ad hoc network. In these two networks, we use discrete convex analysis to study the interval of resolution parameter of H and D that will not cause the misidentification. By comparison, we find that in both examples, for Hamiltonian function H, the larger the value of resolution parameter γ, the less resolution limit the network suffers; while for modularity density D, the less resolution limit the network suffers when we decrease the value of γ. Our framework is mathematically strict and efficient and can be applied in a lot of scientific fields.

Achieving superresolution with illumination-enhanced sparsity.

PubMed

Yu, Jiun-Yann; Becker, Stephen R; Folberth, James; Wallin, Bruce F; Chen, Simeng; Cogswell, Carol J

2018-04-16

Recent advances in superresolution fluorescence microscopy have been limited by a belief that surpassing two-fold resolution enhancement of the Rayleigh resolution limit requires stimulated emission or the fluorophore to undergo state transitions. Here we demonstrate a new superresolution method that requires only image acquisitions with a focused illumination spot and computational post-processing. The proposed method utilizes the focused illumination spot to effectively reduce the object size and enhance the object sparsity and consequently increases the resolution and accuracy through nonlinear image post-processing. This method clearly resolves 70nm resolution test objects emitting ~530nm light with a 1.4 numerical aperture (NA) objective, and, when imaging through a 0.5NA objective, exhibits high spatial frequencies comparable to a 1.4NA widefield image, both demonstrating a resolution enhancement above two-fold of the Rayleigh resolution limit. More importantly, we examine how the resolution increases with photon numbers, and show that the more-than-two-fold enhancement is achievable with realistic photon budgets.

Alignment limit of the NMSSM Higgs sector

DOE PAGES

Carena, Marcela; Haber, Howard E.; Low, Ian; ...

2016-02-17

The Next-to-Minimal Supersymmetric extension of the Standard Model (NMSSM) with a Higgs boson of mass 125 GeV can be compatible with stop masses of order of the electroweak scale, thereby reducing the degree of fine-tuning necessary to achieve electroweak symmetry breaking. Moreover, in an attractive region of the NMSSM parameter space, corresponding to the \\alignment limit" in which one of the neutral Higgs fields lies approximately in the same direction in field space as the doublet Higgs vacuum expectation value, the observed Higgs boson is predicted to have Standard- Model-like properties. We derive analytical expressions for the alignment conditions andmore » show that they point toward a more natural region of parameter space for electroweak symmetry breaking, while allowing for perturbativity of the theory up to the Planck scale. Additionally, the alignment limit in the NMSSM leads to a well defined spectrum in the Higgs and Higgsino sectors, and yields a rich and interesting Higgs boson phenomenology that can be tested at the LHC. Here, we discuss the most promising channels for discovery and present several benchmark points for further study.« less

Erosion in extruder flow

NASA Astrophysics Data System (ADS)

Kaufman, Miron; Fodor, Petru S.

A detailed analysis of the fluid flow in Tadmor's unwound channel model of the single screw extruder is performed by combining numerical and analytical methods. Using the analytical solution for the longitudinal velocity field (in the limit of zero Reynolds number) allows us to devote all the computational resources solely for a detailed numerical solution of the transversal velocity field. This high resolution 3D model of the fluid flow in a single-screw extruder allows us to identify the position and extent of Moffatt eddies that impede mixing. We further consider the erosion of particles (e.g. carbon-black agglomerates) advected by the polymeric flow. We assume a particle to be made of primary fragments bound together. In the erosion process a primary fragment breaks out of a given particle. Particles are advected by the laminar flow and they disperse because of the shear stresses imparted by the fluid. The time evolution of the numbers of particles of different sizes is described by the Bateman coupled differential equations used to model radioactivity. Using the particle size distribution we compute an entropic fragmentation index which varies from 0 for a monodisperse system to 1 for an extreme poly-disperse system.

Computational model of chromosome aberration yield induced by high- and low-LET radiation exposures.

PubMed

Ponomarev, Artem L; George, Kerry; Cucinotta, Francis A

2012-06-01

We present a computational model for calculating the yield of radiation-induced chromosomal aberrations in human cells based on a stochastic Monte Carlo approach and calibrated using the relative frequencies and distributions of chromosomal aberrations reported in the literature. A previously developed DNA-fragmentation model for high- and low-LET radiation called the NASARadiationTrackImage model was enhanced to simulate a stochastic process of the formation of chromosomal aberrations from DNA fragments. The current version of the model gives predictions of the yields and sizes of translocations, dicentrics, rings, and more complex-type aberrations formed in the G(0)/G(1) cell cycle phase during the first cell division after irradiation. As the model can predict smaller-sized deletions and rings (<3 Mbp) that are below the resolution limits of current cytogenetic analysis techniques, we present predictions of hypothesized small deletions that may be produced as a byproduct of properly repaired DNA double-strand breaks (DSB) by nonhomologous end-joining. Additionally, the model was used to scale chromosomal exchanges in two or three chromosomes that were obtained from whole-chromosome FISH painting analysis techniques to whole-genome equivalent values.

Breakdown of String Perturbation Theory for Many External Particles.

PubMed

Ghosh, Sudip; Raju, Suvrat

2017-03-31

We consider massless string scattering amplitudes in a limit where the number of external particles becomes very large, while the energy of each particle remains small. Using the growth of the volume of the relevant moduli space, and by means of independent numerical evidence, we argue that string perturbation theory breaks down in this limit. We discuss some remarkable implications for the information paradox.

Break-even analysis of Medicaid vs fee for service in orthodontic practice: North Carolina as a case study.

PubMed

Murdock, John E; Phillips, Ceib; Beane, Richard; Quinonez, Rocio

2010-03-01

Access to orthodontic services for children enrolled in Medicaid is limited nationwide. Orthodontists cite low fee reimbursement as a significant barrier to Medicaid participation. The purpose of this study was to examine, under a specific set of practice assumptions, the simulated effect on profitability of treating patients covered by Medicaid in orthodontic practices in North Carolina by using a break-even analysis for the 2005 fiscal year. Questionnaires were mailed to 154 orthodontists in active practice in North Carolina. The response rate was 58%. Seventy respondents met the eligibility criteria. Respondents were categorized into 4 groups based on the number of 2005 Medicaid case starts (I, 0; II, 1-5; III, 6-12; IV, 13 or more). By using the aggregated responses for treatment fees, treatment times, and overhead percentages for each group, average per-patient costs were calculated for each group and used in a break-even analysis. Group I accounted for 60% of respondents; group II, 20%; group III, 9%; and group IV, 11%. Assuming that the break-even point had not been reached, the group I practice would have an average estimated loss of $164 per patient whereas groups II, III, and IV would realize average profits from $98 to $256. The break-even point increased slightly in groups I, II, and III after the total number of patients in the patient pool was increased by 5%, assuming that additional patients were enrolled in Medicaid: group I, 203 to 210; group II, 220 to 226; group III, 158 to 160. The break-even point for group IV was 234 patients. Assuming that the break-even point had been reached, all groups were estimated to realize average per-patient profits of $1483 to $1897. Break-even analysis is a basic economic concept applicable to orthodontic practices. Under the specific conditions of this study, the inclusion of 5% of patients enrolled in Medicaid in the active patient pool had minimal effect on the financial break-even point and, assuming that the break-even point had been reached, was unlikely to have a negative financial impact on the practice. 2010 American Association of Orthodontists. Published by Mosby, Inc. All rights reserved.

Swarm v2: highly-scalable and high-resolution amplicon clustering

PubMed Central

Quince, Christopher; de Vargas, Colomban; Dunthorn, Micah

2015-01-01

Previously we presented Swarm v1, a novel and open source amplicon clustering program that produced fine-scale molecular operational taxonomic units (OTUs), free of arbitrary global clustering thresholds and input-order dependency. Swarm v1 worked with an initial phase that used iterative single-linkage with a local clustering threshold (d), followed by a phase that used the internal abundance structures of clusters to break chained OTUs. Here we present Swarm v2, which has two important novel features: (1) a new algorithm for d = 1 that allows the computation time of the program to scale linearly with increasing amounts of data; and (2) the new fastidious option that reduces under-grouping by grafting low abundant OTUs (e.g., singletons and doubletons) onto larger ones. Swarm v2 also directly integrates the clustering and breaking phases, dereplicates sequencing reads with d = 0, outputs OTU representatives in fasta format, and plots individual OTUs as two-dimensional networks. PMID:26713226

Rift migration explains continental margin asymmetry and crustal hyper-extension

PubMed Central

Brune, Sascha; Heine, Christian; Pérez-Gussinyé, Marta; Sobolev, Stephan V.

2014-01-01

When continents break apart, continental crust and lithosphere are thinned until break-up is achieved and an oceanic basin is formed. The most remarkable and least understood structures associated with this process are up to 200 km wide areas of hyper-extended continental crust, which are partitioned between conjugate margins with pronounced asymmetry. Here we show, using high-resolution thermo-mechanical modelling, that hyper-extended crust and margin asymmetry are produced by steady state rift migration. We demonstrate that rift migration is accomplished by sequential, oceanward-younging, upper crustal faults, and is balanced through lower crustal flow. Constraining our model with a new South Atlantic plate reconstruction, we demonstrate that larger extension velocities may account for southward increasing width and asymmetry of these conjugate magma-poor margins. Our model challenges conventional ideas of rifted margin evolution, as it implies that during rift migration large amounts of material are transferred from one side of the rift zone to the other. PMID:24905463

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

Ushizima, Daniela; Perciano, Talita; Krishnan, Harinarayan

Fibers provide exceptional strength-to-weight ratio capabilities when woven into ceramic composites, transforming them into materials with exceptional resistance to high temperature, and high strength combined with improved fracture toughness. Microcracks are inevitable when the material is under strain, which can be imaged using synchrotron X-ray computed micro-tomography (mu-CT) for assessment of material mechanical toughness variation. An important part of this analysis is to recognize fibrillar features. This paper presents algorithms for detecting and quantifying composite cracks and fiber breaks from high-resolution image stacks. First, we propose recognition algorithms to identify the different structures of the composite, including matrix cracks andmore » fibers breaks. Second, we introduce our package F3D for fast filtering of large 3D imagery, implemented in OpenCL to take advantage of graphic cards. Results show that our algorithms automatically identify micro-damage and that the GPU-based implementation introduced here takes minutes, being 17x faster than similar tools on a typical image file.« less

Recombination Proteins Mediate Meiotic Spatial Chromosome Organization and Pairing

PubMed Central

Storlazzi, Aurora; Gargano, Silvana; Ruprich-Robert, Gwenael; Falque, Matthieu; David, Michelle; Kleckner, Nancy; Zickler, Denise

2010-01-01

SUMMARY Meiotic chromosome pairing involves not only recognition of homology but also juxtaposition of entire chromosomes in a topologically regular way. Analysis of filamentous fungus Sordaria macrospora reveals that recombination proteins Mer3, Msh4 and Mlh1 play direct roles in all of these aspects, in advance of their known roles in recombination. Absence of Mer3 helicase results in interwoven chromosomes, thereby revealing the existence of features that specifically ensure “entanglement avoidance”. Entanglements that remain at zygotene, i.e. “interlockings”, require Mlh1 for resolution, likely to eliminate constraining recombinational connections. Patterns of Mer3 and Msh4 foci along aligned chromosomes show that the double-strand breaks mediating homologous alignment have spatially separated ends, one localized to each partner axis, and that pairing involves interference among developing interhomolog interactions. We propose that Mer3, Msh4 and Mlh1 execute all of these roles during pairing by modulating the state of nascent double-strand break/partner DNA contacts within axis-associated recombination complexes. PMID:20371348

Small Rad51 and Dmc1 Complexes Often Co-occupy Both Ends of a Meiotic DNA Double Strand Break

PubMed Central

Brown, M. Scott; Grubb, Jennifer; Zhang, Annie; Rust, Michael J.; Bishop, Douglas K.

2015-01-01

The Eukaryotic RecA-like proteins Rad51 and Dmc1 cooperate during meiosis to promote recombination between homologous chromosomes by repairing programmed DNA double strand breaks (DSBs). Previous studies showed that Rad51 and Dmc1 form partially overlapping co-foci. Here we show these Rad51-Dmc1 co-foci are often arranged in pairs separated by distances of up to 400 nm. Paired co-foci remain prevalent when DSBs are dramatically reduced or when strand exchange or synapsis is blocked. Super-resolution dSTORM microscopy reveals that individual foci observed by conventional light microscopy are often composed of two or more substructures. The data support a model in which the two tracts of ssDNA formed by a single DSB separate from one another by distances of up to 400 nm, with both tracts often bound by one or more short (about 100 nt) Rad51 filaments and also by one or more short Dmc1 filaments. PMID:26719980

DNA Breaks and End Resection Measured Genome-wide by End Sequencing.

PubMed

Canela, Andres; Sridharan, Sriram; Sciascia, Nicholas; Tubbs, Anthony; Meltzer, Paul; Sleckman, Barry P; Nussenzweig, André

2016-09-01

DNA double-strand breaks (DSBs) arise during physiological transcription, DNA replication, and antigen receptor diversification. Mistargeting or misprocessing of DSBs can result in pathological structural variation and mutation. Here we describe a sensitive method (END-seq) to monitor DNA end resection and DSBs genome-wide at base-pair resolution in vivo. We utilized END-seq to determine the frequency and spectrum of restriction-enzyme-, zinc-finger-nuclease-, and RAG-induced DSBs. Beyond sequence preference, chromatin features dictate the repertoire of these genome-modifying enzymes. END-seq can detect at least one DSB per cell among 10,000 cells not harboring DSBs, and we estimate that up to one out of 60 cells contains off-target RAG cleavage. In addition to site-specific cleavage, we detect DSBs distributed over extended regions during immunoglobulin class-switch recombination. Thus, END-seq provides a snapshot of DNA ends genome-wide, which can be utilized for understanding genome-editing specificities and the influence of chromatin on DSB pathway choice. Published by Elsevier Inc.

Chromosome rearrangements via template switching between diverged repeated sequences

PubMed Central

Anand, Ranjith P.; Tsaponina, Olga; Greenwell, Patricia W.; Lee, Cheng-Sheng; Du, Wei; Petes, Thomas D.

2014-01-01

Recent high-resolution genome analyses of cancer and other diseases have revealed the occurrence of microhomology-mediated chromosome rearrangements and copy number changes. Although some of these rearrangements appear to involve nonhomologous end-joining, many must have involved mechanisms requiring new DNA synthesis. Models such as microhomology-mediated break-induced replication (MM-BIR) have been invoked to explain these rearrangements. We examined BIR and template switching between highly diverged sequences in Saccharomyces cerevisiae, induced during repair of a site-specific double-strand break (DSB). Our data show that such template switches are robust mechanisms that give rise to complex rearrangements. Template switches between highly divergent sequences appear to be mechanistically distinct from the initial strand invasions that establish BIR. In particular, such jumps are less constrained by sequence divergence and exhibit a different pattern of microhomology junctions. BIR traversing repeated DNA sequences frequently results in complex translocations analogous to those seen in mammalian cells. These results suggest that template switching among repeated genes is a potent driver of genome instability and evolution. PMID:25367035

The Autumn of break-ups: When Jakobshavn Isbrae lost its floating tongue

NASA Astrophysics Data System (ADS)

Aschwanden, A.; Fahnestock, M. A.; Truffer, M.; Motyka, R. J.

2015-12-01

Capturing the temporal variability in outlet glacier flow remains one of the holy grails in ice sheet modeling. Here we demonstrate progress using the three-dimensional Parallel Ice Sheet Model. Using a first-order calving law and prescribed subshelf basal melt rates, we performed high-resolution (<1km) hindcasts of the Greenland Ice Sheet of the 1989-2012 period. These hindcasts allow us to study the processes governing ice-shelf thinning, break-up, and subsequent speed-ups and dynamic thinning. Focussing our analysis on the Jakobshavn basin we show that our simulations are able to capture the thinning of the floating tongue resulting from increased subshelf basal melt rates. Furthermore, our simulations capture both the magnitude and the timing of the dynamic thinning associated with the loss of the floating tongue, as well as the speed-up. We find little seasonal variations in surface speeds prior to 1995, and strong variations thereafter, in good agreement with observations of Echelmeyer and Harrison (1991) and Joughin et al (2012).

Large scale superres 3D imaging: light-sheet single-molecule localization microscopy (Conference Presentation)

NASA Astrophysics Data System (ADS)

Lu, Chieh Han; Chen, Peilin; Chen, Bi-Chang

2017-02-01

Optical imaging techniques provide much important information in understanding life science especially cellular structure and morphology because "seeing is believing". However, the resolution of optical imaging is limited by the diffraction limit, which is discovered by Ernst Abbe, i.e. λ/2(NA) (NA is the numerical aperture of the objective lens). Fluorescence super-resolution microscopic techniques such as Stimulated emission depletion microscopy (STED), Photoactivated localization microscopy (PALM), and Stochastic optical reconstruction microscopy (STORM) are invented to have the capability of seeing biological entities down to molecular level that are smaller than the diffraction limit (around 200-nm in lateral resolution). These techniques do not physically violate the Abbe limit of resolution but exploit the photoluminescence properties and labelling specificity of fluorescence molecules to achieve super-resolution imaging. However, these super-resolution techniques limit most of their applications to the 2D imaging of fixed or dead samples due to the high laser power needed or slow speed for the localization process. Extended from 2D imaging, light sheet microscopy has been proven to have a lot of applications on 3D imaging at much better spatiotemporal resolutions due to its intrinsic optical sectioning and high imaging speed. Herein, we combine the advantage of localization microscopy and light-sheet microscopy to have super-resolved cellular imaging in 3D across large field of view. With high-density labeled spontaneous blinking fluorophore and wide-field detection of light-sheet microscopy, these allow us to construct 3D super-resolution multi-cellular imaging at high speed ( minutes) by light-sheet single-molecule localization microscopy.

Beyond Orbital-Motion-Limited theory effects for dust transport in tokamaks

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

Delzanno, Gian Luca; Tang, Xianzhu

Dust transport in tokamaks is very important for ITER. Can many kilograms of dust really accumulate in the device? Can the dust survive? The conventional dust transport model is based on Orbital-Motion-Limited theory (OML). But OML can break in the limit where the dust grain becomes positively charged due to electron emission processes because it overestimates the dust collected power. An OML + approximation of the emitted electrons trapped/passing boundary is shown to be in good agreement with PIC simulations.

Parity breaking signatures from a Chern-Simons coupling during inflation: the case of non-Gaussian gravitational waves

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

Bartolo, Nicola; Orlando, Giorgio, E-mail: nicola.bartolo@pd.infn.it, E-mail: giorgio.orlando@phd.unipd.it

Considering high-energy modifications of Einstein gravity during inflation is an interesting issue. We can constrain the strength of the new gravitational terms through observations of inflationary imprints in the actual universe. In this paper we analyze the effects on slow-roll models due to a Chern-Simons term coupled to the inflaton field through a generic coupling function f (φ). A well known result is the polarization of primordial gravitational waves (PGW) into left and right eigenstates, as a consequence of parity breaking. In such a scenario the modifications to the power spectrum of PGW are suppressed under the conditions that allowmore » to avoid the production of ghost gravitons at a certain energy scale, the so-called Chern-Simons mass M {sub CS}. In general it has been recently pointed out that there is very little hope to efficiently constrain chirality of PGW on the basis solely of two-point statistics from future CMB data, even in the most optimistic cases. Thus we search if significant parity breaking signatures can arise at least in the bispectrum statistics. We find that the tensor-tensor-scalar bispectra ( γ γ ζ ) for each polarization state are the only ones that are not suppressed. Their amplitude, setting the level of parity breaking during inflation, is proportional to the second derivative of the coupling function f (φ) and they turn out to be maximum in the squeezed limit. We comment on the squeezed-limit consistency relation arising in the case of chiral gravitational waves, and on possible observables to constrain these signatures.« less

Determination of chloride in brazilian crude oils by ion chromatography after extraction induced by emulsion breaking.

PubMed

Robaina, Nicolle F; Feiteira, Fernanda N; Cassella, Alessandra R; Cassella, Ricardo J

2016-08-05

The present paper reports on the development of a novel extraction induced by emulsion breaking (EIEB) method for the determination of chloride in crude oils. The proposed method was based on the formation and breaking of oil-in-water emulsions with the samples and the consequential transference of the highly water-soluble chloride to the aqueous phase during emulsion breaking, which was achieved by centrifugation. The determination of chloride in the extracts was performed by ion chromatography (IC) with conductivity detection. Several parameters (oil phase:aqueous phase ratio, crude oil:mineral oil ratio, shaking time and type and concentration of surfactant) that could affect the performance of the method were evaluated. Total extraction of chloride from samples could be achieved when 1.0g of oil phase (0.5g of sample+0.5g of mineral oil) was emulsified in 5mL of a 2.5% (m/v) solution of Triton X-114. The obtained emulsion was shaken for 60min and broken by centrifugation for 5min at 5000rpm. The separated aqueous phase was collected, filtered and diluted before analysis by IC. Under these conditions, the limit of detection was 0.5μgg(-1) NaCl and the limit of quantification was 1.6μgg(-1) NaCl. We applied the method to the determination of chloride in six Brazilian crude oils and the results did not differ statistically from those obtained by the ASTM D6470 method when the paired Student-t-test, at 95% confidence level, was applied. Copyright © 2016 Elsevier B.V. All rights reserved.

Peripheral detection and resolution with mid-/long-wavelength and short-wavelength sensitive cone systems.

PubMed

Zhu, Hai-Feng; Zele, Andrew J; Suheimat, Marwan; Lambert, Andrew J; Atchison, David A

2016-08-01

This study compared neural resolution and detection limits of the human mid-/long-wavelength and short-wavelength cone systems with anatomical estimates of photoreceptor and retinal ganglion cell spacings and sizes. Detection and resolution limits were measured from central fixation out to 35° eccentricity across the horizontal visual field using a modified Lotmar interferometer. The mid-/long-wavelength cone system was studied using a green (550 nm) test stimulus to which S-cones have low sensitivity. To bias resolution and detection to the short-wavelength cone system, a blue (450 nm) test stimulus was presented against a bright yellow background that desensitized the M- and L-cones. Participants were three trichromatic males with normal visual functions. With green stimuli, resolution showed a steep central-peripheral gradient that was similar between participants, whereas the detection gradient was shallower and patterns were different between participants. Detection and resolution with blue stimuli were poorer than for green stimuli. The detection of blue stimuli was superior to resolution across the horizontal visual field and the patterns were different between participants. The mid-/long-wavelength cone system's resolution is limited by midget ganglion cell spacing and its detection is limited by the size of the M- and L-cone photoreceptors, consistent with previous observations. We found that no such simple relationships occur for the short-wavelength cone system between resolution and the bistratified ganglion cell spacing, nor between detection and the S-cone photoreceptor sizes.

Imaging multicellular specimens with real-time optimized tiling light-sheet selective plane illumination microscopy

PubMed Central

Fu, Qinyi; Martin, Benjamin L.; Matus, David Q.; Gao, Liang

2016-01-01

Despite the progress made in selective plane illumination microscopy, high-resolution 3D live imaging of multicellular specimens remains challenging. Tiling light-sheet selective plane illumination microscopy (TLS-SPIM) with real-time light-sheet optimization was developed to respond to the challenge. It improves the 3D imaging ability of SPIM in resolving complex structures and optimizes SPIM live imaging performance by using a real-time adjustable tiling light sheet and creating a flexible compromise between spatial and temporal resolution. We demonstrate the 3D live imaging ability of TLS-SPIM by imaging cellular and subcellular behaviours in live C. elegans and zebrafish embryos, and show how TLS-SPIM can facilitate cell biology research in multicellular specimens by studying left-right symmetry breaking behaviour of C. elegans embryos. PMID:27004937

Visible rodent brain-wide networks at single-neuron resolution

PubMed Central

Yuan, Jing; Gong, Hui; Li, Anan; Li, Xiangning; Chen, Shangbin; Zeng, Shaoqun; Luo, Qingming

2015-01-01

There are some unsolvable fundamental questions, such as cell type classification, neural circuit tracing and neurovascular coupling, though great progresses are being made in neuroscience. Because of the structural features of neurons and neural circuits, the solution of these questions needs us to break through the current technology of neuroanatomy for acquiring the exactly fine morphology of neuron and vessels and tracing long-distant circuit at axonal resolution in the whole brain of mammals. Combined with fast-developing labeling techniques, efficient whole-brain optical imaging technology emerging at the right moment presents a huge potential in the structure and function research of specific-function neuron and neural circuit. In this review, we summarize brain-wide optical tomography techniques, review the progress on visible brain neuronal/vascular networks benefit from these novel techniques, and prospect the future technical development. PMID:26074784

Weak data do not make a free lunch, only a cheap meal

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

Luo, Zhipu; Rajashankar, Kanagalaghatta; Dauter, Zbigniew

2014-01-17

Four data sets were processed at resolutions significantly exceeding the criteria traditionally used for estimating the diffraction data resolution limit. The analysis of these data and the corresponding model-quality indicators suggests that the criteria of resolution limits widely adopted in the past may be somewhat conservative. Various parameters, such asR mergeandI/σ(I), optical resolution and the correlation coefficients CC 1/2and CC*, can be used for judging the internal data quality, whereas the reliability factorsRandR freeas well as the maximum-likelihood target values and real-space map correlation coefficients can be used to estimate the agreement between the data and the refined model. However,more » none of these criteria provide a reliable estimate of the data resolution cutoff limit. The analysis suggests that extension of the maximum resolution by about 0.2 Å beyond the currently adopted limit where theI/σ(I) value drops to 2.0 does not degrade the quality of the refined structural models, but may sometimes be advantageous. Such an extension may be particularly beneficial for significantly anisotropic diffraction. Extension of the maximum resolution at the stage of data collection and structure refinement is cheap in terms of the required effort and is definitely more advisable than accepting a too conservative resolution cutoff, which is unfortunately quite frequent among the crystal structures deposited in the Protein Data Bank.« less

LITE microscopy: Tilted light-sheet excitation of model organisms offers high resolution and low photobleaching

PubMed Central

Gerbich, Therese M.; Rana, Kishan; Suzuki, Aussie; Schaefer, Kristina N.; Heppert, Jennifer K.; Boothby, Thomas C.; Allbritton, Nancy L.; Gladfelter, Amy S.; Maddox, Amy S.

2018-01-01

Fluorescence microscopy is a powerful approach for studying subcellular dynamics at high spatiotemporal resolution; however, conventional fluorescence microscopy techniques are light-intensive and introduce unnecessary photodamage. Light-sheet fluorescence microscopy (LSFM) mitigates these problems by selectively illuminating the focal plane of the detection objective by using orthogonal excitation. Orthogonal excitation requires geometries that physically limit the detection objective numerical aperture (NA), thereby limiting both light-gathering efficiency (brightness) and native spatial resolution. We present a novel live-cell LSFM method, lateral interference tilted excitation (LITE), in which a tilted light sheet illuminates the detection objective focal plane without a sterically limiting illumination scheme. LITE is thus compatible with any detection objective, including oil immersion, without an upper NA limit. LITE combines the low photodamage of LSFM with high resolution, high brightness, and coverslip-based objectives. We demonstrate the utility of LITE for imaging animal, fungal, and plant model organisms over many hours at high spatiotemporal resolution. PMID:29490939

Search for Long-Lived Neutral Particles in Final States with Delayed Photon and Missing Transverse Energy from Proton-Proton Collisions Using the CMS detector

NASA Astrophysics Data System (ADS)

Tambe Ebai, Norbert

We perform a search for long-lived neutral particles in final state with delayed photons and large missing transverse energy produced in LHC proton-proton collisions at center-of-mass energy, √s = 8 TeV. Capitalizing on the excellent timing resolution of the CMS Electromagnetic Calorimeter the search uses photon time measurements made by the Electromagnetic Calorimeter as the main search quantity. We found a single event consistent with our background expectations from the Standard Model and set a model-independent upper limit of 4.37 on number of signal events. We also interpret our results in the context of the SPS8 benchmark GMSB model and show that neutralinos with mean lifetime, tau PSneutralinoOne ≤ 45 ns, and mass, mPSneutralinoOne ≤ 300 GeV/c2, or effective Supersymmetry breaking energy scale, Lambda ≤ 220TeV, are ruled out of existence at 95% CLS confidence level. The exclusion limit on the product of the production cross-section and branching ratio of the neutralino to photon and gravitino decay channel, sigma(PSneutralinoOne → gamma + G˜) x BR, for different lifetimes and masses is derived. Our results confirm for the first time that the CMS Electromagnetic Calorimeter provides good sensitivity to search for long-lived neutral particles with lifetimes up to 40 ns and masses up to 300 GeV/c2 using only timing measurements.

A multi-resolution analysis of lidar-DTMs to identify geomorphic processes from characteristic topographic length scales

NASA Astrophysics Data System (ADS)

Sangireddy, H.; Passalacqua, P.; Stark, C. P.

2013-12-01

Characteristic length scales are often present in topography, and they reflect the driving geomorphic processes. The wide availability of high resolution lidar Digital Terrain Models (DTMs) allows us to measure such characteristic scales, but new methods of topographic analysis are needed in order to do so. Here, we explore how transitions in probability distributions (pdfs) of topographic variables such as (log(area/slope)), defined as topoindex by Beven and Kirkby[1979], can be measured by Multi-Resolution Analysis (MRA) of lidar DTMs [Stark and Stark, 2001; Sangireddy et al.,2012] and used to infer dominant geomorphic processes such as non-linear diffusion and critical shear. We show this correlation between dominant geomorphic processes to characteristic length scales by comparing results from a landscape evolution model to natural landscapes. The landscape evolution model MARSSIM Howard[1994] includes components for modeling rock weathering, mass wasting by non-linear creep, detachment-limited channel erosion, and bedload sediment transport. We use MARSSIM to simulate steady state landscapes for a range of hillslope diffusivity and critical shear stresses. Using the MRA approach, we estimate modal values and inter-quartile ranges of slope, curvature, and topoindex as a function of resolution. We also construct pdfs at each resolution and identify and extract characteristic scale breaks. Following the approach of Tucker et al.,[2001], we measure the average length to channel from ridges, within the GeoNet framework developed by Passalacqua et al.,[2010] and compute pdfs for hillslope lengths at each scale defined in the MRA. We compare the hillslope diffusivity used in MARSSIM against inter-quartile ranges of topoindex and hillslope length scales, and observe power law relationships between the compared variables for simulated landscapes at steady state. We plot similar measures for natural landscapes and are able to qualitatively infer the dominant geomorphic processes. Also, we explore the variability in hillslope length scales as a function of hillslope diffusivity coefficients and critical shear stress in natural landscapes and show that we can infer signatures of dominant geomorphic processes by analyzing characteristic topographic length scales present in topography. References: Beven, K. and Kirkby, M. J.: A physically based variable contributing area model of basin hydrology, Hydrol. Sci. Bull., 24, 43-69, 1979 Howard, A. D. (1994). A detachment-limited model of drainage basin evolution.Water resources research, 30(7), 2261-2285. Passalacqua, P., Do Trung, T., Foufoula Georgiou, E., Sapiro, G., & Dietrich, W. E. (2010). A geometric framework for channel network extraction from lidar: Nonlinear diffusion and geodesic paths. Journal of Geophysical. Research: Earth Surface (2003-2012), 115(F1). Sangireddy, H., Passalacqua, P., Stark, C.P.(2012). Multi-resolution estimation of lidar-DTM surface flow metrics to identify characteristic topographic length scales, EP13C-0859: AGU Fall meeting 2012. Stark, C. P., & Stark, G. J. (2001). A channelization model of landscape evolution. American Journal of Science, 301(4-5), 486-512. Tucker, G. E., Catani, F., Rinaldo, A., & Bras, R. L. (2001). Statistical analysis of drainage density from digital terrain data. Geomorphology, 36(3), 187-202.

A synthesis of the literature on breaking bad news or truth telling: potential for research in India.

PubMed

Martis, Lawrence; Westhues, Anne

2013-01-01

The high incidence of fatal diseases, inequitable access to health care, and socioeconomic disparities in India generate plentiful clinical bad news including diagnosis of a life-limiting disease, poor prognosis, treatment failure, and impending death. These contexts compel health care professionals to become the messengers of bad news to patients and their families. In global literature on breaking bad news, there is very little about such complex clinical interactions occurring in India or guiding health care providers to do it well. The purpose of this article is to identify the issues for future research that would contribute to the volume, comprehensiveness, and quality of empirical literature on breaking bad news in clinical settings across India. Towards this end, we have synthesized the studies done across the globe on breaking bad news, under four themes: (a) deciding the amount of bad news to deliver; (b) attending to cultural and ethical issues; (c) managing psychological distress; and (d) producing competent messengers of bad news. We believe that robust research is inevitable to build an indigenous knowledge base, enhance communicative competence among health care professionals, and thereby to improve the quality of clinical interactions in India.

Broken chiral symmetry on a null plane

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

Beane, Silas R., E-mail: silas@physics.unh.edu

2013-10-15

On a null-plane (light-front), all effects of spontaneous chiral symmetry breaking are contained in the three Hamiltonians (dynamical Poincaré generators), while the vacuum state is a chiral invariant. This property is used to give a general proof of Goldstone’s theorem on a null-plane. Focusing on null-plane QCD with N degenerate flavors of light quarks, the chiral-symmetry breaking Hamiltonians are obtained, and the role of vacuum condensates is clarified. In particular, the null-plane Gell-Mann–Oakes–Renner formula is derived, and a general prescription is given for mapping all chiral-symmetry breaking QCD condensates to chiral-symmetry conserving null-plane QCD condensates. The utility of the null-planemore » description lies in the operator algebra that mixes the null-plane Hamiltonians and the chiral symmetry charges. It is demonstrated that in a certain non-trivial limit, the null-plane operator algebra reduces to the symmetry group SU(2N) of the constituent quark model. -- Highlights: •A proof (the first) of Goldstone’s theorem on a null-plane is given. •The puzzle of chiral-symmetry breaking condensates on a null-plane is solved. •The emergence of spin-flavor symmetries in null-plane QCD is demonstrated.« less

A Synthesis of the Literature on Breaking Bad News or Truth Telling: Potential for Research in India

PubMed Central

Martis, Lawrence; Westhues, Anne

2013-01-01

The high incidence of fatal diseases, inequitable access to health care, and socioeconomic disparities in India generate plentiful clinical bad news including diagnosis of a life-limiting disease, poor prognosis, treatment failure, and impending death. These contexts compel health care professionals to become the messengers of bad news to patients and their families. In global literature on breaking bad news, there is very little about such complex clinical interactions occurring in India or guiding health care providers to do it well. The purpose of this article is to identify the issues for future research that would contribute to the volume, comprehensiveness, and quality of empirical literature on breaking bad news in clinical settings across India. Towards this end, we have synthesized the studies done across the globe on breaking bad news, under four themes: (a) deciding the amount of bad news to deliver; (b) attending to cultural and ethical issues; (c) managing psychological distress; and (d) producing competent messengers of bad news. We believe that robust research is inevitable to build an indigenous knowledge base, enhance communicative competence among health care professionals, and thereby to improve the quality of clinical interactions in India. PMID:23766589

Low level phosphorylation of histone H2AX on serine 139 (γH2AX) is not associated with DNA double-strand breaks.

PubMed

Rybak, Paulina; Hoang, Agnieszka; Bujnowicz, Lukasz; Bernas, Tytus; Berniak, Krzysztof; Zarębski, Mirosław; Darzynkiewicz, Zbigniew; Dobrucki, Jerzy

2016-08-02

Phosphorylation of histone H2AX on serine 139 (γH2AX) is an early step in cellular response to a DNA double-strand break (DSB). γH2AX foci are generally regarded as markers of DSBs. A growing body of evidence demonstrates, however, that while induction of DSBs always brings about phosphorylation of histone H2AX, the reverse is not true - the presence of γH2AX foci should not be considered an unequivocal marker of DNA double-strand breaks. We studied DNA damage induced in A549 human lung adenocarcinoma cells by topoisomerase type I and II inhibitors (0.2 μM camptothecin, 10 μM etoposide or 0.2 μM mitoxantrone for 1 h), and using 3D high resolution quantitative confocal microscopy, assessed the number, size and the integrated intensity of immunofluorescence signals of individual γH2AX foci induced by these drugs. Also, investigated was spatial association between γH2AX foci and foci of 53BP1, the protein involved in DSB repair, both in relation to DNA replication sites (factories) as revealed by labeling nascent DNA with EdU. Extensive 3D and correlation data analysis demonstrated that γH2AX foci exhibit a wide range of sizes and levels of H2AX phosphorylation, and correlate differently with 53BP1 and DNA replication. This is the first report showing lack of a link between low level phosphorylation γH2AX sites and double-strand DNA breaks in cells exposed to topoisomerase I or II inhibitors. The data are discussed in terms of mechanisms that may be involved in formation of γH2AX sites of different sizes and intensities.

Regionally Varying Assessments of Tropical Width in Reanalyses and CMIP5 Models Using a Tropopause Break Metric

NASA Astrophysics Data System (ADS)

Homeyer, C. R.; Martin, E. R.; McKinzie, R.; McCarthy, K.

2017-12-01

The boundary between the tropics and the extratropics in each hemisphere is not fixed in space or time. Variations in the north-south width of the tropics are directly connected to changes in weather and climate. These fluctuations have been shown to impact tropical biodiversity, the spread of vector borne diseases, atmospheric chemistry, and additional natural and human sectors. However, there is no unanimous definition of the tropical boundary. This has led to a disagreement on the magnitude of changes in the tropical width during the past 30 years and a lack of understanding concerning its spatial and temporal variability. This study identifies the variability of the tropical width in modern reanalyses (ERA-Interim, JRA-55, CFSR, MERRA, and MERRA-2) and CMIP5 models (all models with available 6-hourly output) using a novel analysis metric: the tropopause "break" (i.e., the sharp discontinuity in tropopause altitude between the tropics and extratropics). Similarities and differences are found amongst the reanalyses, with some degree of tropical narrowing in the Eastern Pacific between 1981 and 2010. Historical simulations from the CMIP5 models agree well with the tropopause break latitudes depicted by the reanalyses, with considerable differences in estimated trends over the relatively short overlapping time period of the datasets. For future projections under the RCP8.5 scenario from 2006 to 2100, CMIP5 models generally show statistically significant increases in tropical width (at the 99% level) throughout each hemisphere, with regional variability of 1-2 degrees in poleward latitude trends. The impact of CMIP5 model grid resolution and other factors on the results of the tropopause break analysis will be discussed.

Mastering high resolution tip-enhanced Raman spectroscopy: towards a shift of perception.

PubMed

Richard-Lacroix, Marie; Zhang, Yao; Dong, Zhenchao; Deckert, Volker

2017-07-03

Recent years have seen tremendous improvement of our understanding of high resolution reachable in TERS experiments, forcing us to re-evaluate our understanding of the intrinsic limits of this field, but also exposing several inconsistencies. On the one hand, more and more recent experimental results have provided us with clear indications of spatial resolutions down to a few nanometres or even on the subnanometre scale. Moreover, lessons learned from recent theoretical investigations clearly support such high resolutions, and vice versa the obvious theoretical impossibility to evade high resolution from a purely plasmonic point of view. On the other hand, most of the published TERS results still, to date, claim a resolution on the order of tens of nanometres that would be somehow limited by the tip apex, a statement well accepted for the past 2 decades. Overall, this now leads the field to a fundamental question: how can this divergence be justified? The answer to this question brings up an equally critical one: how can this gap be bridged? This review aims at raising a fundamental discussion related to the resolution limits of tip-enhanced Raman spectroscopy, at revisiting our comprehension of the factors limiting it both from a theoretical and an experimental point of view and at providing indications on how to move the field ahead. It is our belief that a much deeper understanding of the real accessible lateral resolution in TERS and the practical factors that limit them will simultaneously help us to fully explore the potential of this technique for studying nanoscale features in organic, inorganic and biological systems, and also to improve both the reproducibility and the accuracy of routine TERS studies. A significant improvement of our comprehension of the accessible resolution in TERS is thus critical for a broad audience, even in certain contexts where high resolution TERS is not the desired outcome.

Extending the process limits of laser polymer welding with high-brilliance beam sources (recent status and prospects of POLYBRIGHT)

NASA Astrophysics Data System (ADS)

Olowinsky, A.; Boglea, A.

2011-03-01

Plastics play an important role in almost every facet of our lives and constitute a wide variety of products, from everyday products such as food and beverage packaging, over furniture and building materials to high tech products in the automotive, electronics, aerospace, white goods, medical and other sectors [1]. The objective of PolyBright, the European Research project on laser polymer welding, is to provide high speed and flexible laser manufacturing technology and expand the limits of current plastic part assembly. New laser polymer joining processes for optimized thermal management in combination with adapted wavelengths will provide higher quality, high processing speed up to 1 m/s and robust manufacturing processes at lower costs. Key innovations of the PolyBright project are fibre lasers with high powers up to 500 W, high speed scanning and flexible beam manipulation systems for simultaneous welding and high-resolution welding, such as dynamic masks and multi kHz scanning heads. With this initial step, PolyBright will break new paths in processing of advanced plastic products overcoming the quality and speed limitations of conventional plastic part assembly. Completely new concepts for high speed processing, flexibility and quality need to be established in combination with high brilliance lasers and related equipment. PolyBright will thus open new markets for laser systems with a short term potential of over several 100 laser installations per year and a future much larger market share in the still growing plastic market. PolyBright will hence establish a comprehensive and sustainable development activity on new high brilliance lasers that will strengthen the laser system industry.

Can phenological models predict tree phenology accurately under climate change conditions?

NASA Astrophysics Data System (ADS)

Chuine, Isabelle; Bonhomme, Marc; Legave, Jean Michel; García de Cortázar-Atauri, Inaki; Charrier, Guillaume; Lacointe, André; Améglio, Thierry

2014-05-01

The onset of the growing season of trees has been globally earlier by 2.3 days/decade during the last 50 years because of global warming and this trend is predicted to continue according to climate forecast. The effect of temperature on plant phenology is however not linear because temperature has a dual effect on bud development. On one hand, low temperatures are necessary to break bud dormancy, and on the other hand higher temperatures are necessary to promote bud cells growth afterwards. Increasing phenological changes in temperate woody species have strong impacts on forest trees distribution and productivity, as well as crops cultivation areas. Accurate predictions of trees phenology are therefore a prerequisite to understand and foresee the impacts of climate change on forests and agrosystems. Different process-based models have been developed in the last two decades to predict the date of budburst or flowering of woody species. They are two main families: (1) one-phase models which consider only the ecodormancy phase and make the assumption that endodormancy is always broken before adequate climatic conditions for cell growth occur; and (2) two-phase models which consider both the endodormancy and ecodormancy phases and predict a date of dormancy break which varies from year to year. So far, one-phase models have been able to predict accurately tree bud break and flowering under historical climate. However, because they do not consider what happens prior to ecodormancy, and especially the possible negative effect of winter temperature warming on dormancy break, it seems unlikely that they can provide accurate predictions in future climate conditions. It is indeed well known that a lack of low temperature results in abnormal pattern of bud break and development in temperate fruit trees. An accurate modelling of the dormancy break date has thus become a major issue in phenology modelling. Two-phases phenological models predict that global warming should delay or compromise dormancy break at the species equatorward range limits leading to a delay or even impossibility to flower or set new leaves. These models are classically parameterized with flowering or budburst dates only, with no information on the dormancy break date because this information is very scarce. We evaluated the efficiency of a set of process-based phenological models to accurately predict the dormancy break dates of four fruit trees. Our results show that models calibrated solely with flowering or budburst dates do not accurately predict the dormancy break date. Providing dormancy break date for the model parameterization results in much more accurate simulation of this latter, with however a higher error than that on flowering or bud break dates. But most importantly, we show also that models not calibrated with dormancy break dates can generate significant differences in forecasted flowering or bud break dates when using climate scenarios. Our results claim for the urgent need of massive measurements of dormancy break dates in forest and fruit trees to yield more robust projections of phenological changes in a near future.

High-Resolution Global Analysis of the Influences of Bas1 and Ino4 Transcription Factors on Meiotic DNA Break Distributions in Saccharomyces cerevisiae

PubMed Central

Zhu, Xuan; Keeney, Scott

2015-01-01

Meiotic recombination initiates with DNA double-strand breaks (DSBs) made by Spo11. In Saccharomyces cerevisiae, many DSBs occur in “hotspots” coinciding with nucleosome-depleted gene promoters. Transcription factors (TFs) stimulate DSB formation in some hotspots, but TF roles are complex and variable between locations. Until now, available data for TF effects on global DSB patterns were of low spatial resolution and confined to a single TF. Here, we examine at high resolution the contributions of two TFs to genome-wide DSB distributions: Bas1, which was known to regulate DSB activity at some loci, and Ino4, for which some binding sites were known to be within strong DSB hotspots. We examined fine-scale DSB distributions in TF mutant strains by deep sequencing oligonucleotides that remain covalently bound to Spo11 as a byproduct of DSB formation, mapped Bas1 and Ino4 binding sites in meiotic cells, evaluated chromatin structure around DSB hotspots, and measured changes in global messenger RNA levels. Our findings show that binding of these TFs has essentially no predictive power for DSB hotspot activity and definitively support the hypothesis that TF control of DSB numbers is context dependent and frequently indirect. TFs often affected the fine-scale distributions of DSBs within hotspots, and when seen, these effects paralleled effects on local chromatin structure. In contrast, changes in DSB frequencies in hotspots did not correlate with quantitative measures of chromatin accessibility, histone H3 lysine 4 trimethylation, or transcript levels. We also ruled out hotspot competition as a major source of indirect TF effects on DSB distributions. Thus, counter to prevailing models, roles of these TFs on DSB hotspot strength cannot be simply explained via chromatin “openness,” histone modification, or compensatory interactions between adjacent hotspots. PMID:26245832

Shot-noise-limited monitoring and phase locking of the motion of a single trapped ion.

PubMed

Bushev, P; Hétet, G; Slodička, L; Rotter, D; Wilson, M A; Schmidt-Kaler, F; Eschner, J; Blatt, R

2013-03-29

We perform a high-resolution real-time readout of the motion of a single trapped and laser-cooled Ba+ ion. By using an interferometric setup, we demonstrate a shot-noise-limited measurement of thermal oscillations with a resolution of 4 times the standard quantum limit. We apply the real-time monitoring for phase control of the ion motion through a feedback loop, suppressing the photon recoil-induced phase diffusion. Because of the spectral narrowing in the phase-locked mode, the coherent ion oscillation is measured with a resolution of about 0.3 times the standard quantum limit.

A Locally Generated High-Mode Nonlinear Internal Wave Detected on the Shelf of the Northern South China Sea From Marine Seismic Observations

NASA Astrophysics Data System (ADS)

Tang, Qunshu; Xu, Min; Zheng, Chan; Xu, Xing; Xu, Jiang

2018-02-01

In this work, a secondary nonlinear internal wave (NIW) on the continental shelf of the northern South China Sea is investigated using high-resolution seismic imaging and joint inversion of water structure properties combined with in situ hydrographic observations. It is an extraordinary wave combination with two mode-2 NIWs and one elevated NIW occurring within a short distance of 2 km. The most energetic part of the NIW could be regarded as a mode-2 NIW in the upper layer between 40 and 120 m depth. The vertical particle velocity of ˜41 cm/s may exceed the critical value of wave breaking and thus collapse the strong stratification followed by a series of processes including internal wave breaking, overturning, Kelvin-Helmholtz instability, stratification splitting, and eventual restratification. Among these processes, the shear-induced Kelvin-Helmholtz instability is directly imaged using the seismic method for the first time. The stratification splitting and restratification show that the unstable stage lasts only for a few hours and spans several kilometers. It is a new observation that the elevated NIW could be generated in a deepwater region (as deep as ˜370 m). Different from the periodical NIWs originating from the Luzon Strait, this secondary NIW is most likely generated locally, at the continental shelf break during ebb tide.

Lyman Break Analogs: Constraints on the Formation of Extreme Starbursts at Low and High Redshift

NASA Technical Reports Server (NTRS)

Goncalves, Thiago S.; Overzier, Roderik; Basu-Zych, Antara; Martin, D. Christopher

2011-01-01

Lyman Break Analogs (LBAs), characterized by high far-UV luminosities and surface brightnesses as detected by GALEX, are intensely star-forming galaxies in the low-redshift universe (z approximately equal to 0.2), with star formation rates reaching up to 50 times that of the Milky Way. These objects present metallicities, morphologies and other physical properties similar to higher redshift Lyman Break Galaxies (LBGs), motivating the detailed study of LBAs as local laboratories of this high-redshift galaxy population. We present results from our recent integral-field spectroscopy survey of LBAs with Keck/OSIRIS, which shows that these galaxies have the same nebular gas kinematic properties as high-redshift LBGs. We argue that such kinematic studies alone are not an appropriate diagnostic to rule out merger events as the trigger for the observed starburst. Comparison between the kinematic analysis and morphological indices from HST imaging illustrates the difficulties of properly identifying (minor or major) merger events, with no clear correlation between the results using either of the two methods. Artificial redshifting of our data indicates that this problem becomes even worse at high redshift due to surface brightness dimming and resolution loss. Whether mergers could generate the observed kinematic properties is strongly dependent on gas fractions in these galaxies. We present preliminary results of a CARMA survey for LBAs and discuss the implications of the inferred molecular gas masses for formation models.

Modeling the Flexural Rigidity of Rod Photoreceptors

PubMed Central

Haeri, Mohammad; Knox, Barry E.; Ahmadi, Aphrodite

2013-01-01

In vertebrate eyes, the rod photoreceptor has a modified cilium with an extended cylindrical structure specialized for phototransduction called the outer segment (OS). The OS has numerous stacked membrane disks and can bend or break when subjected to mechanical forces. The OS exhibits axial structural variation, with extended bands composed of a few hundred membrane disks whose thickness is diurnally modulated. Using high-resolution confocal microscopy, we have observed OS flexing and disruption in live transgenic Xenopus rods. Based on the experimental observations, we introduce a coarse-grained model of OS mechanical rigidity using elasticity theory, representing the axial OS banding explicitly via a spring-bead model. We calculate a bending stiffness of ∼105 nN⋅μm2, which is seven orders-of-magnitude larger than that of typical cilia and flagella. This bending stiffness has a quadratic relation to OS radius, so that thinner OS have lower fragility. Furthermore, we find that increasing the spatial frequency of axial OS banding decreases OS rigidity, reducing its fragility. Moreover, the model predicts a tendency for OS to break in bands with higher spring number density, analogous to the experimental observation that transgenic rods tended to break preferentially in bands of high fluorescence. We discuss how pathological alterations of disk membrane properties by mutant proteins may lead to increased OS rigidity and thus increased breakage, ultimately contributing to retinal degeneration. PMID:23442852

High-Resolution Mapping of Two Types of Spontaneous Mitotic Gene Conversion Events in Saccharomyces cerevisiae

PubMed Central

Yim, Eunice; O’Connell, Karen E.; St. Charles, Jordan; Petes, Thomas D.

2014-01-01

Gene conversions and crossovers are related products of the repair of double-stranded DNA breaks by homologous recombination. Most previous studies of mitotic gene conversion events have been restricted to measuring conversion tracts that are <5 kb. Using a genetic assay in which the lengths of very long gene conversion tracts can be measured, we detected two types of conversions: those with a median size of ∼6 kb and those with a median size of >50 kb. The unusually long tracts are initiated at a naturally occurring recombination hotspot formed by two inverted Ty elements. We suggest that these long gene conversion events may be generated by a mechanism (break-induced replication or repair of a double-stranded DNA gap) different from the short conversion tracts that likely reflect heteroduplex formation followed by DNA mismatch repair. Both the short and long mitotic conversion tracts are considerably longer than those observed in meiosis. Since mitotic crossovers in a diploid can result in a heterozygous recessive deleterious mutation becoming homozygous, it has been suggested that the repair of DNA breaks by mitotic recombination involves gene conversion events that are unassociated with crossing over. In contrast to this prediction, we found that ∼40% of the conversion tracts are associated with crossovers. Spontaneous mitotic crossover events in yeast are frequent enough to be an important factor in genome evolution. PMID:24990991

Off-axis Gamma-ray Burst Afterglow Modeling Based on a Two-dimensional Axisymmetric Hydrodynamics Simulation

NASA Astrophysics Data System (ADS)

van Eerten, Hendrik; Zhang, Weiqun; MacFadyen, Andrew

2010-10-01

Starting as highly relativistic collimated jets, gamma-ray burst outflows gradually slow down and become nonrelativistic spherical blast waves. Although detailed analytical solutions describing the afterglow emission received by an on-axis observer during both the early and late phases of the outflow evolution exist, a calculation of the received flux during the intermediate phase and for an off-axis observer requires either a more simplified analytical model or direct numerical simulations of the outflow dynamics. In this paper, we present light curves for off-axis observers covering the long-term evolution of the blast wave, calculated from a high-resolution two-dimensional relativistic hydrodynamics simulation using a synchrotron radiation model. We compare our results to earlier analytical work and calculate the consequence of the observer angle with respect to the jet axis both for the detection of orphan afterglows and for jet break fits to the observational data. We confirm earlier results in the literature finding that only a very small number of local type Ibc supernovae can harbor an orphan afterglow. For off-axis observers, the observable jet break can be delayed up to several weeks, potentially leading to overestimation of the beaming-corrected total energy. In addition we find that, when using our off-axis light curves to create synthetic Swift X-ray data, jet breaks are likely to remain hidden in the data.

Relativistic Anandan quantum phase and the Aharonov–Casher effect under Lorentz symmetry breaking effects in the cosmic string spacetime

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

Bakke, K., E-mail: kbakke@fisica.ufpb.br; Furtado, C., E-mail: furtado@fisica.ufpb.br; Belich, H., E-mail: belichjr@gmail.com

2016-09-15

From the modified Maxwell theory coupled to gravity, we establish a possible scenario of the violation of the Lorentz symmetry and write an effective metric for the cosmic string spacetime. Then, we investigate the arising of an analogue of the Anandan quantum phase for a relativistic Dirac neutral particle with a permanent magnetic dipole moment in the cosmic string spacetime under Lorentz symmetry breaking effects. Besides, we analyse the influence of the effects of the Lorentz symmetry violation and the topology of the defect on the Aharonov–Casher geometric quantum phase in the nonrelativistic limit.

Minimal but non-minimal inflation and electroweak symmetry breaking

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

Marzola, Luca; Institute of Physics, University of Tartu,Ravila 14c, 50411 Tartu; Racioppi, Antonio

2016-10-07

We consider the most minimal scale invariant extension of the standard model that allows for successful radiative electroweak symmetry breaking and inflation. The framework involves an extra scalar singlet, that plays the rôle of the inflaton, and is compatibile with current experimental bounds owing to the non-minimal coupling of the latter to gravity. This inflationary scenario predicts a very low tensor-to-scalar ratio r≈10{sup −3}, typical of Higgs-inflation models, but in contrast yields a scalar spectral index n{sub s}≃0.97 which departs from the Starobinsky limit. We briefly discuss the collider phenomenology of the framework.

Seeking Ways to Break Energy Storage Limits

DTIC Science & Technology

2016-05-02

system sizes that we simulated. 15. SUBJECT TERMS density functional theory, guest-host structures, carbon nanotubes , free atom limit, geometry...unlimited. iii Contents List of Figures iv 1. Introduction 1 2. Xenon-Buckminsterfullerene (Xe-C60) 3 3. Xe-C980 4 4. Xe-Carbon Nanotube (CNT) 4 5...calculations. 4. Xe-Carbon Nanotube (CNT) Because of our inability to attain guest-host complexes that would achieve energies in excess of the

Super-Resolution Scanning Laser Microscopy Based on Virtually Structured Detection

PubMed Central

Zhi, Yanan; Wang, Benquan; Yao, Xincheng

2016-01-01

Light microscopy plays a key role in biological studies and medical diagnosis. The spatial resolution of conventional optical microscopes is limited to approximately half the wavelength of the illumination light as a result of the diffraction limit. Several approaches—including confocal microscopy, stimulated emission depletion microscopy, stochastic optical reconstruction microscopy, photoactivated localization microscopy, and structured illumination microscopy—have been established to achieve super-resolution imaging. However, none of these methods is suitable for the super-resolution ophthalmoscopy of retinal structures because of laser safety issues and inevitable eye movements. We recently experimentally validated virtually structured detection (VSD) as an alternative strategy to extend the diffraction limit. Without the complexity of structured illumination, VSD provides an easy, low-cost, and phase artifact–free strategy to achieve super-resolution in scanning laser microscopy. In this article we summarize the basic principles of the VSD method, review our demonstrated single-point and line-scan super-resolution systems, and discuss both technical challenges and the potential of VSD-based instrumentation for super-resolution ophthalmoscopy of the retina. PMID:27480461

Low-lying baryon spectrum with two dynamical twisted mass fermions

NASA Astrophysics Data System (ADS)

Alexandrou, C.; Baron, R.; Carbonell, J.; Drach, V.; Guichon, P.; Jansen, K.; Korzec, T.; Pène, O.

2009-12-01

The masses of the low-lying baryons are evaluated using two degenerate flavors of twisted mass sea quarks corresponding to pseudoscalar masses in the range of about 270-500 MeV. The strange valence quark mass is tuned to reproduce the mass of the kaon in the physical limit. The tree-level Symanzik improved gauge action is employed. We use lattices of spatial size 2.1 and 2.7 fm at two values of the lattice spacing with r0/a=5.22(2) and r0/a=6.61(3). We check for both finite volume and cutoff effects on the baryon masses. We performed a detailed study of the chiral extrapolation of the octet and decuplet masses using SU(2) χPT. The lattice spacings determined using the nucleon mass at the physical point are consistent with the values extracted using the pion decay constant. We examine the issue of isospin symmetry breaking for the octet and decuplet baryons and its dependence on the lattice spacing. We show that in the continuum limit isospin breaking is consistent with zero, as expected. The baryon masses that we find after taking the continuum limit and extrapolating to the physical limit are in good agreement with experiment.

Hard X-ray Optics Technology Development for Astronomy at the Marshall Space Flight Center

NASA Technical Reports Server (NTRS)

Gubarev, Mikhail; Ramsey, Brian; Kilaru, Kiranmayee

2009-01-01

Grazing-incidence telescopes based on Wolter 1 geometry have delivered impressive advances in astrophysics at soft-x-ray wavelengths, while the hard xray region remains relatively unexplored at fine angular resolution and high sensitivities. The ability to perform ground-breaking science in the hard-x-ray energy range had been the motivation for technology developments aimed at fabricating low-cost, light-weight, high-quality x-ray mirrors. Grazing-incidence x-ray optics for high-energy astrophysical applications is being developed at MSFC using the electroform-nickel replication process.

A fast algorithm for computer aided collimation gamma camera (CACAO)

NASA Astrophysics Data System (ADS)

Jeanguillaume, C.; Begot, S.; Quartuccio, M.; Douiri, A.; Franck, D.; Pihet, P.; Ballongue, P.

2000-08-01

The computer aided collimation gamma camera is aimed at breaking down the resolution sensitivity trade-off of the conventional parallel hole collimator. It uses larger and longer holes, having an added linear movement at the acquisition sequence. A dedicated algorithm including shift and sum, deconvolution, parabolic filtering and rotation is described. Examples of reconstruction are given. This work shows that a simple and fast algorithm, based on a diagonal dominant approximation of the problem can be derived. Its gives a practical solution to the CACAO reconstruction problem.

Printing colour at the optical diffraction limit.

PubMed

Kumar, Karthik; Duan, Huigao; Hegde, Ravi S; Koh, Samuel C W; Wei, Jennifer N; Yang, Joel K W

2012-09-01

The highest possible resolution for printed colour images is determined by the diffraction limit of visible light. To achieve this limit, individual colour elements (or pixels) with a pitch of 250 nm are required, translating into printed images at a resolution of ∼100,000 dots per inch (d.p.i.). However, methods for dispensing multiple colourants or fabricating structural colour through plasmonic structures have insufficient resolution and limited scalability. Here, we present a non-colourant method that achieves bright-field colour prints with resolutions up to the optical diffraction limit. Colour information is encoded in the dimensional parameters of metal nanostructures, so that tuning their plasmon resonance determines the colours of the individual pixels. Our colour-mapping strategy produces images with both sharp colour changes and fine tonal variations, is amenable to large-volume colour printing via nanoimprint lithography, and could be useful in making microimages for security, steganography, nanoscale optical filters and high-density spectrally encoded optical data storage.

"Breaking up is hard to do": the formation and resolution of sister chromatid intertwines.

PubMed

Baxter, Jonathan

2015-02-13

The absolute necessity to resolve every intertwine between the two strands of the DNA double helix provides a massive challenge to the cellular processes that duplicate and segregate chromosomes. Although the overwhelming majority of intertwines between the parental DNA strands are resolved during DNA replication, there are numerous chromosomal contexts where some intertwining is maintained into mitosis. These mitotic sister chromatid intertwines (SCIs) can be found as; short regions of unreplicated DNA, fully replicated and intertwined sister chromatids--commonly referred to as DNA catenation--and as sister chromatid linkages generated by homologous recombination-associated processes. Several overlapping mechanisms, including intra-chromosomal compaction, topoisomerase action and Holliday junction resolvases, ensure that all SCIs are removed before they can prevent normal chromosome segregation. Here, I discuss why some DNA intertwines persist into mitosis and review our current knowledge of the SCI resolution mechanisms that are employed in both prokaryotes and eukaryotes, including how deregulating SCI formation during DNA replication or disrupting the resolution processes may contribute to aneuploidy in cancer. Copyright © 2014 Elsevier Ltd. All rights reserved.

The PMC-Turbo Balloon Mission to Study Gravity Waves and Turbulence through High-Resolution Imaging of Polar Mesospheric Clouds

NASA Astrophysics Data System (ADS)

Williams, B. P.; Kjellstrand, B.; Jones, G.; Reimuller, J. D.; Fritts, D. C.; Miller, A.; Geach, C.; Limon, M.; Hanany, S.; Kaifler, B.; Wang, L.; Taylor, M. J.

2017-12-01

PMC-Turbo is a NASA long-duration, high-altitude balloon mission that will deploy 7 high-resolution cameras to image polar mesospheric clouds (PMC) and measure gravity wave breakdown and turbulence. The mission has been enhanced by the addition of the DLR Balloon Lidar Experiment (BOLIDE) and an OH imager from Utah State University. This instrument suite will provide high horizontal and vertical resolution of the wave-modified PMC structure along a several thousand kilometer flight track. We have requested a flight from Kiruna, Sweden to Canada in June 2017 or McMurdo Base, Antarctica in Dec 2017. Three of the PMC camera systems were deployed on an aircraft and two tomographic ground sites for the High Level campaign in Canada in June/July 2017. On several nights the cameras observed PMC's with strong gravity wave breaking signatures. One PMC camera will piggyback on the Super Tiger mission scheduled to be launched in Dec 2017 from McMurdo, so we will obtain PMC images and wave/turbulence data from both the northern and southern hemispheres.

Super-resolution imaging of subcortical white matter using stochastic optical reconstruction microscopy (STORM) and super-resolution optical fluctuation imaging (SOFI).

PubMed

Hainsworth, A H; Lee, S; Foot, P; Patel, A; Poon, W W; Knight, A E

2018-06-01

The spatial resolution of light microscopy is limited by the wavelength of visible light (the 'diffraction limit', approximately 250 nm). Resolution of sub-cellular structures, smaller than this limit, is possible with super resolution methods such as stochastic optical reconstruction microscopy (STORM) and super-resolution optical fluctuation imaging (SOFI). We aimed to resolve subcellular structures (axons, myelin sheaths and astrocytic processes) within intact white matter, using STORM and SOFI. Standard cryostat-cut sections of subcortical white matter from donated human brain tissue and from adult rat and mouse brain were labelled, using standard immunohistochemical markers (neurofilament-H, myelin-associated glycoprotein, glial fibrillary acidic protein, GFAP). Image sequences were processed for STORM (effective pixel size 8-32 nm) and for SOFI (effective pixel size 80 nm). In human, rat and mouse, subcortical white matter high-quality images for axonal neurofilaments, myelin sheaths and filamentous astrocytic processes were obtained. In quantitative measurements, STORM consistently underestimated width of axons and astrocyte processes (compared with electron microscopy measurements). SOFI provided more accurate width measurements, though with somewhat lower spatial resolution than STORM. Super resolution imaging of intact cryo-cut human brain tissue is feasible. For quantitation, STORM can under-estimate diameters of thin fluorescent objects. SOFI is more robust. The greatest limitation for super-resolution imaging in brain sections is imposed by sample preparation. We anticipate that improved strategies to reduce autofluorescence and to enhance fluorophore performance will enable rapid expansion of this approach. © 2017 British Neuropathological Society.

Flavour symmetry breaking in the kaon parton distribution amplitude

DOE PAGES

none,

2014-11-01

We compute the kaon's valence-quark (twist-two parton) distribution amplitude (PDA) by projecting its Poincaré-covariant Bethe–Salpeter wave-function onto the light-front. At a scale ζ = 2 GeV, the PDA is a broad, concave and asymmetric function, whose peak is shifted 12–16% away from its position in QCD's conformal limit. These features are a clear expression of SU(3)-flavour-symmetry breaking. They show that the heavier quark in the kaon carries more of the bound-state's momentum than the lighter quark and also that emergent phenomena in QCD modulate the magnitude of flavour-symmetry breaking: it is markedly smaller than one might expect based on themore » difference between light-quark current masses. Our results add to a body of evidence which indicates that at any energy scale accessible with existing or foreseeable facilities, a reliable guide to the interpretation of experiment requires the use of such nonperturbatively broadened PDAs in leading-order, leading-twist formulae for hard exclusive processes instead of the asymptotic PDA associated with QCD's conformal limit. We illustrate this via the ratio of kaon and pion electromagnetic form factors: using our nonperturbative PDAs in the appropriate formulae, F K/F π=1.23 at spacelike-Q 2=17 GeV 2, which compares satisfactorily with the value of 0.92(5) inferred in e +e - annihilation at s=17 GeV 2.« less

Un formalisme de systemes a sauts pour la recirculation optimale des casses dans une machine a papier

NASA Astrophysics Data System (ADS)

Khanbaghi, Maryam

Increasing closure of white water circuits is making mill productivity and quality of paper produced increasingly affected by the occurrence of paper breaks. In this thesis the main objective is the development of white water and broke recirculation policies. The thesis consists of three main parts, respectively corresponding to the synthesis of a statistical model of paper breaks in a paper mill, the basic mathematical setup for the formulation of white water and broke recirculation policies in the mill as a jump linear quadratic regulation problem, and finally the tuning of the control law based on first passage-time theory, and its extension to the case of control sensitive paper break rates. More specifically, in the first part a statistical model of paper machine breaks is developed. We start from the hypothesis that the breaks process is a Markov chain with three states: the first state is the operational one, while the two others are associated with the general types of paper-breaks that can take place in the mill (wet breaks and dry breaks). The Markovian hypothesis is empirically validated. We also establish how paper-break rates are correlated with machine speed and broke recirculation ratio. Subsequently, we show how the obtained Markov chain model of paper-breaks can be used to formulate a machine operating speed parameter optimization problem. In the second part, upon recognizing that paper breaks can be modelled as a Markov chain type of process which, when interacting with the continuous mill dynamics, yields a jump Markov model, jump linear theory is proposed as a means of constructing white water and broke recirculation strategies which minimize process variability. Reduced process variability comes at the expense of relatively large swings in white water and broke tanks level. Since the linear design does not specifically account for constraints on the state-space, under the resulting law, damaging events of tank overflow or emptiness can occur. A heuristic simulation-based approach is proposed to choose the performance measure design parameters to keep the mean time between incidents of fluid in broke and white water tanks either overflowing, or reaching dangerously low levels, sufficiently long. In the third part, a methodology, mainly founded on the first passage-time theory of stochastic processes, is proposed to choose the performance measure design parameters to limit process variability while accounting for the possibility of undesirable tank overflows or tank emptiness. The heart of the approach is an approximation technique for evaluating mean first passage-times of the controlled tanks levels. This technique appears to have an applicability which largely exceeds the problem area it was designed for. Furthermore, the introduction of control sensitive break rates and the analysis of the ensuing control problem are presented. This is to account for the experimentally observed increase in breaks concomitant with flow rate variability.

Phytoplankton Distribution in Relation to Environmental Drivers on the North West European Shelf Sea.

PubMed

Siemering, Beatrix; Bresnan, Eileen; Painter, Stuart C; Daniels, Chris J; Inall, Mark; Davidson, Keith

2016-01-01

The edge of the North West European Shelf (NWES) is characterised by a steep continental slope and a northward flowing slope current. These topographic/hydrographic features separate oceanic water and shelf water masses hence potentially separate phytoplankton communities. The slope current may facilitate the advective transport of phytoplankton, with mixing at the shelf edge supporting nutrient supply and therefore phytoplankton production. On the west Scottish shelf in particular, little is known about the phytoplankton communities in and around the shelf break and adjacent waters. Hence, to improve our understanding of environmental drivers of phytoplankton communities, biological and environmental data were collected on seven cross-shelf transects across the Malin and Hebridean Shelves during autumn 2014. Density profiles indicated that shelf break and oceanic stations had a 100 m deep mixed surface layer while stations on the shelf were generally well mixed. Analysis of similarity and multidimensional scaling of phytoplankton counts revealed that phytoplankton communities on the shelf were significantly different to those found at the shelf break and at oceanic stations. Shelf stations were dominated by dinoflagellates, with diatoms contributing a maximum of 37% of cells. Shelf break and oceanic stations were also dinoflagellate dominated but displayed a lower species diversity. Significant difference between shelf and shelf break stations suggested that the continental slope limited cross shelf phytoplankton exchange. Northern and southern phytoplankton communities on the shelf were approximately 15% dissimilar while there was no latitudinal gradient for stations along the slope current, suggesting this current provided south to north connectivity. Fitting environmental data to phytoplankton ordination showed a significant relationship between phytoplankton community dissimilarities and nutrient concentrations and light availability on the shelf compared to shelf break and oceanic stations in the study area.

CORRELATIONS IN HORIZONTAL BRANCH OSCILLATIONS AND BREAK COMPONENTS IN XTE J1701-462 AND GX 17+2

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

Bu, Qing-cui; Chen, Li; Zhang, Liang

2015-01-20

We studied the horizontal branch oscillations (HBO) and the band-limited components observed in the power spectra of the transient neutron star low-mass X-ray binary XTE J1701-462 and the persistent ''Sco-like'' Z source GX 17+2. These two components were studied based on the state-resolved spectra. We found that the frequencies of XTE J1701-462 lie on the known correlations (WK and PBK), showing consistency with other types of X-ray binaries (black holes, atoll sources, and millisecond X-ray pulsars). However, GX 17+2 is shifted from the WK correlation like other typical Z sources. We suggest that the WK/PBK main track forms a boundarymore » that separates persistent sources from transient sources. The characteristic frequencies of break and HBO are independent of accretion rate in both sources, though it depends on spectral models. We also report the energy dependence of the HBO and break frequencies in XTE J1701-462 and how the temporal properties change with spectral state in XTE J1701-462 and GX 17+2. We studied the correlation between rms at the break and the HBO frequency. We suggest that HBO and break components for both sources probably arise from a similar physical mechanism: Comptonization emission from the corona. These two components could be caused by the same kind of oscillation in a corona with uneven density, and they could be generated from different areas of the corona. We further suggest that different proportions of the Comptonization component in the total flux cause the different distribution between GX 17+2 and XTE J1701-462 in the rms{sub break}-rms{sub HBO} diagram.« less

Explanation for excessive DNA single-strand breaks and endogenous repair foci in pluripotent mouse embryonic stem cells.

PubMed

Banáth, J P; Bañuelos, C A; Klokov, D; MacPhail, S M; Lansdorp, P M; Olive, P L

2009-05-01

Pluripotent mouse embryonic stem cells (mES cells) exhibit approximately 100 large gammaH2AX repair foci in the absence of measurable numbers of DNA double-strand breaks. Many of these cells also show excessive numbers of DNA single-strand breaks (>10,000 per cell) when analyzed using the alkaline comet assay. To understand the reasons for these unexpected observations, various methods for detecting DNA strand breaks were applied to wild-type mES cells and to mES cells lacking H2AX, ATM, or DNA-PKcs. H2AX phosphorylation and expression of other repair complexes were measured using flow and image analysis of antibody-stained cells. Results indicate that high numbers of endogenous gammaH2AX foci and single-strand breaks in pluripotent mES cells do not require ATM or DNA-PK kinase activity and appear to be associated with global chromatin decondensation rather than pre-existing DNA damage. This will limit applications of gammaH2AX foci analysis in mES cells to relatively high levels of initial or residual DNA damage. Excessive numbers of single-strand breaks in the alkaline comet assay can be explained by the vulnerability of replicating chromatin in mES cells to osmotic shock. This suggests that caution is needed in interpreting results with the alkaline comet assay when applied to certain cell types or after treatment with agents that make chromatin vulnerable to osmotic changes. Differentiation of mES cells caused a reduction in histone acetylation, gammaH2AX foci intensity, and DNA single-strand breakage, providing a link between chromatin structural organization, excessive gammaH2AX foci, and sensitivity of replicating mES cell chromatin to osmotic shock.

Phytoplankton Distribution in Relation to Environmental Drivers on the North West European Shelf Sea

PubMed Central

Siemering, Beatrix; Bresnan, Eileen; Painter, Stuart C.; Daniels, Chris J.; Inall, Mark; Davidson, Keith

2016-01-01

The edge of the North West European Shelf (NWES) is characterised by a steep continental slope and a northward flowing slope current. These topographic/hydrographic features separate oceanic water and shelf water masses hence potentially separate phytoplankton communities. The slope current may facilitate the advective transport of phytoplankton, with mixing at the shelf edge supporting nutrient supply and therefore phytoplankton production. On the west Scottish shelf in particular, little is known about the phytoplankton communities in and around the shelf break and adjacent waters. Hence, to improve our understanding of environmental drivers of phytoplankton communities, biological and environmental data were collected on seven cross-shelf transects across the Malin and Hebridean Shelves during autumn 2014. Density profiles indicated that shelf break and oceanic stations had a 100 m deep mixed surface layer while stations on the shelf were generally well mixed. Analysis of similarity and multidimensional scaling of phytoplankton counts revealed that phytoplankton communities on the shelf were significantly different to those found at the shelf break and at oceanic stations. Shelf stations were dominated by dinoflagellates, with diatoms contributing a maximum of 37% of cells. Shelf break and oceanic stations were also dinoflagellate dominated but displayed a lower species diversity. Significant difference between shelf and shelf break stations suggested that the continental slope limited cross shelf phytoplankton exchange. Northern and southern phytoplankton communities on the shelf were approximately 15% dissimilar while there was no latitudinal gradient for stations along the slope current, suggesting this current provided south to north connectivity. Fitting environmental data to phytoplankton ordination showed a significant relationship between phytoplankton community dissimilarities and nutrient concentrations and light availability on the shelf compared to shelf break and oceanic stations in the study area. PMID:27736920

Preparing Safety Cases for Operating Outside Prescriptive Fatigue Risk Management Regulations.

PubMed

Gander, Philippa; Mangie, Jim; Wu, Lora; van den Berg, Margo; Signal, Leigh; Phillips, Adrienne

2017-07-01

Transport operators seeking to operate outside prescriptive fatigue management regulations are typically required to present a safety case justifying how they will manage the associated risk. This paper details a method for constructing a successful safety case. The method includes four elements: 1) scope (prescriptive rules and operations affected); 2) risk assessment; 3) risk mitigation strategies; and 4) monitoring ongoing risk. A successful safety case illustrates this method. It enables landing pilots in 3-pilot crews to choose the second or third in-flight rest break, rather than the regulatory requirement to take the third break. Scope was defined using a month of scheduled flights that would be covered (N = 4151). These were analyzed in the risk assessment using existing literature on factors affecting fatigue to estimate the maximum time awake at top of descent and sleep opportunities in each break. Additionally, limited data collected before the new regulations showed that pilots flying at landing chose the third break on only 6% of flights. A prospective survey comparing subjective reports (N = 280) of sleep in the second vs. third break and fatigue and sleepiness ratings at top of descent confirmed that the third break is not consistently superior. The safety case also summarized established systems for fatigue monitoring, risk assessment and hazard identification, and multiple fatigue mitigation strategies that are in place. Other successful safety cases have used this method. The evidence required depends on the expected level of risk and should evolve as experience with fatigue risk management systems builds.Gander P, Mangie J, Wu L, van den Berg M, Signal L, Phillips A. Preparing safety cases for operating outside prescriptive fatigue risk management regulations. Aerosp Med Hum Perform. 2017; 88(7):688-696.

Lets Quantify Our Welding Instruction

ERIC Educational Resources Information Center

Shinn, Glen C.

1973-01-01

By using the nick-break test, and the guided bend test, a student of welding can individually assess his performance either in a formal class setting, or at the home, farm, or job. Employment of these tests will tend to limit personal bias in evaluation. (KP)

Breaking Free with Wireless Networks.

ERIC Educational Resources Information Center

Fleischman, John

2002-01-01

Discusses wireless local area networks (LANs) which typically consist of laptop computers that connect to fixed access points via infrared or radio signals. Topics include wide area networks; personal area networks; problems, including limitations of available bandwidth, interference, and security concerns; use in education; interoperability;…

Breaking Barriers and Building Bridges: Using EJ SCREEN and C-FERST for Science

EPA Science Inventory

Communities across the United States are faced with concerns about environmental risks and exposures including air contaminants near roadways, proximity to hazardous waste sites and children’s environmental health. These concerns are compounded by complicated data, limited ...

Observations of the UTLS: An analysis of the double tropopause and its relationship to Rossby waves and the tropopause inversion layer

NASA Astrophysics Data System (ADS)

Peevey, Tanya

The upper troposphere lower stratosphere (UTLS) is a region of minimum temperatures that contains the tropopause. As a transition region between the troposphere and the stratosphere, the UTLS contains various processes that facilitate stratosphere-troposphere exchange (STE) which can redistribute radiatively important species such as water vapor or ozone. One potential marker for STE is the double tropopause (DT). Therefore this study seeks to further understand how DTs form and how they could enhance the current understanding of some STE processes in the UTLS. Using data from the High Resolution Dynamic Limb Sounder (HIRDLS), a data set with high vertical and horizontal resolution, newly discovered DT structures are found over the Pacific and Atlantic oceans that suggest a relationship between the DT and both storm tracks and Rossby waves. The association between DTs and storm tracks is examined by further analyzing the recently discovered and unexpected relationship between the DT and the tropopause inversion layer (TIL) in a developing baroclinic disturbance. Results show an increase in the number of DTs when the lapse rate of the extratropical TIL is less than -2°C/km, i.e. when the TIL is stronger and the local stability is higher. Composites of ERA-Interim DT profiles for three different TIL strengths shows that the vertical motion and relative vorticity both decrease as the TIL increases, which suggests the warm conveyor belt as a mechanism. This is investigated further with a case study analysis of a developing extratropical cyclone in the Pacific Ocean. Additionally, an analysis of DTs in relation to the large scale flow responsible for storm development shows a strong correlation between monthly Rossby wave activity, ozone laminae and DT variability. Further examination shows that if these waves break a DT will be found with a wave breaking event about 30% of the time in the eastern Pacific and eastern Atlantic oceans, both regions of poleward wave breaking. These results highlight a new and more complicated DT structure that is a product of both large scale dynamics and small scale vertical motions, thus adding new information to the current understanding of the UTLS.

Investigation of the limitations of the highly pixilated CdZnTe detector for PET applications

PubMed Central

Komarov, Sergey; Yin, Yongzhi; Wu, Heyu; Wen, Jie; Krawczynski, Henric; Meng, Ling-Jian; Tai, Yuan-Chuan

2016-01-01

We are investigating the feasibility of a high resolution positron emission tomography (PET) insert device based on the CdZnTe detector with 350 μm anode pixel pitch to be integrated into a conventional animal PET scanner to improve its image resolution. In this paper, we have used a simplified version of the multi pixel CdZnTe planar detector, 5 mm thick with 9 anode pixels only. This simplified 9 anode pixel structure makes it possible to carry out experiments without a complete application-specific integrated circuits readout system that is still under development. Special attention was paid to the double pixel (or charge sharing) detections. The following characteristics were obtained in experiment: energy resolution full-width-at-half-maximum (FWHM) is 7% for single pixel and 9% for double pixel photoelectric detections of 511 keV gammas; timing resolution (FWHM) from the anode signals is 30 ns for single pixel and 35 ns for double pixel detections (for photoelectric interactions only the corresponding values are 20 and 25 ns); position resolution is 350 μm in x,y-plane and ~0.4 mm in depth-of-interaction. The experimental measurements were accompanied by Monte Carlo (MC) simulations to find a limitation imposed by spatial charge distribution. Results from MC simulations suggest the limitation of the intrinsic spatial resolution of the CdZnTe detector for 511 keV photoelectric interactions is 170 μm. The interpixel interpolation cannot recover the resolution beyond the limit mentioned above for photoelectric interactions. However, it is possible to achieve higher spatial resolution using interpolation for Compton scattered events. Energy and timing resolution of the proposed 350 μm anode pixel pitch detector is no better than 0.6% FWHM at 511 keV, and 2 ns FWHM, respectively. These MC results should be used as a guide to understand the performance limits of the pixelated CdZnTe detector due to the underlying detection processes, with the understanding of the inherent limitations of MC methods. PMID:23079763

Investigation of the limitations of the highly pixilated CdZnTe detector for PET applications.

PubMed

Komarov, Sergey; Yin, Yongzhi; Wu, Heyu; Wen, Jie; Krawczynski, Henric; Meng, Ling-Jian; Tai, Yuan-Chuan

2012-11-21

We are investigating the feasibility of a high resolution positron emission tomography (PET) insert device based on the CdZnTe detector with 350 µm anode pixel pitch to be integrated into a conventional animal PET scanner to improve its image resolution. In this paper, we have used a simplified version of the multi pixel CdZnTe planar detector, 5 mm thick with 9 anode pixels only. This simplified 9 anode pixel structure makes it possible to carry out experiments without a complete application-specific integrated circuits readout system that is still under development. Special attention was paid to the double pixel (or charge sharing) detections. The following characteristics were obtained in experiment: energy resolution full-width-at-half-maximum (FWHM) is 7% for single pixel and 9% for double pixel photoelectric detections of 511 keV gammas; timing resolution (FWHM) from the anode signals is 30 ns for single pixel and 35 ns for double pixel detections (for photoelectric interactions only the corresponding values are 20 and 25 ns); position resolution is 350 µm in x,y-plane and ∼0.4 mm in depth-of-interaction. The experimental measurements were accompanied by Monte Carlo (MC) simulations to find a limitation imposed by spatial charge distribution. Results from MC simulations suggest the limitation of the intrinsic spatial resolution of the CdZnTe detector for 511 keV photoelectric interactions is 170 µm. The interpixel interpolation cannot recover the resolution beyond the limit mentioned above for photoelectric interactions. However, it is possible to achieve higher spatial resolution using interpolation for Compton scattered events. Energy and timing resolution of the proposed 350 µm anode pixel pitch detector is no better than 0.6% FWHM at 511 keV, and 2 ns FWHM, respectively. These MC results should be used as a guide to understand the performance limits of the pixelated CdZnTe detector due to the underlying detection processes, with the understanding of the inherent limitations of MC methods.

Thermal and Hydrologic Signatures of Soil Controls on Evaporation: A Combined Energy and Water Balance Approach with Implications for Remote Sensing of Evaporation

NASA Technical Reports Server (NTRS)

Salvucci, Guido D.

2000-01-01

The overall goal of this research is to examine the feasibility of applying a newly developed diagnostic model of soil water evaporation to large land areas using remotely sensed input parameters. The model estimates the rate of soil evaporation during periods when it is limited by the net transport resulting from competing effects of capillary rise and drainage. The critical soil hydraulic properties are implicitly estimated via the intensity and duration of the first stage (energy limited) evaporation, removing a major obstacle in the remote estimation of evaporation over large areas. This duration, or 'time to drying' (t(sub d)) is revealed through three signatures detectable in time series of remote sensing variables. The first is a break in soil albedo that occurs as a small vapor transmission zone develops near the surface. The second is a break in either surface to air temperature differences or in the diurnal surface temperature range, both of which indicate increased sensible heat flux (and/or storage) required to balance the decrease in latent heat flux. The third is a break in the temporal pattern of near surface soil moisture. Soil moisture tends to decrease rapidly during stage I drying (as water is removed from storage), and then become more or less constant during soil limited, or 'stage II' drying (as water is merely transmitted from deeper soil storage). The research tasks address: (1) improvements in model structure, including extensions to transpiration and aggregation over spatially variable soil and topographic landscape attributes; and (2) applications of the model using remotely sensed input parameters.

Thermal and Hydrologic Signatures of Soil Controls on Evaporation: A Combined Energy and Water Balance Approach with Implications for Remote Sensing of Evaporation

NASA Technical Reports Server (NTRS)

Salvucci, Guido D.

1997-01-01

The overall goal of this research is to examine the feasibility of applying a newly developed diagnostic model of soil water evaporation to large land areas using remotely sensed input parameters. The model estimates the rate of soil evaporation during periods when it is limited by the net transport resulting from competing effects of capillary rise and drainage. The critical soil hydraulic properties are implicitly estimated via the intensity and duration of the first stage (energy limited) evaporation, removing a major obstacle in the remote estimation of evaporation over large areas. This duration, or "time to drying" (t(sub d)), is revealed through three signatures detectable in time series of remote sensing variables. The first is a break in soil albedo that occurs as a small vapor transmission zone develops near the surface. The second is a break in either surface to air temperature differences or in the diurnal surface temperature range, both of which indicate increased sensible heat flux (and/or storage) required to balance the decrease in latent heat flux. The third is a break in the temporal pattern of near surface soil moisture. Soil moisture tends to decrease rapidly during stage 1 drying (as water is removed from storage), and then become more or less constant during soil limited, or "stage 2" drying (as water is merely transmitted from deeper soil storage). The research tasks address: (1) improvements in model structure, including extensions to transpiration and aggregation over spatially variable soil and topographic landscape attributes; and (2) applications of the model using remotely sensed input parameters.

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

Schulz, H.

In the updating of the Guidelines for PWR`s of the {open_quotes}Reaktor-Sicherheitskommission{close_quotes} (RSK) in 1981 the requirements on the design have been changed with respect to the postulated leaks and breaks in the primary pressure boundary. The major change was a revision in the requirements for pipe whip protection. As a logical consequence of the {open_quotes}concept of basic safety{close_quotes} a guillotine type break or any other break type resulting in a large opening is not postulated any longer for the calculation of reaction and jet forces. As an upper limit for a leak an area of 0, 1 A (A =more » open cross section of the pipe) is postulated. This decision was based on a general assessment of the present PWR system design in Germany. Since then a number of piping systems have been requalified in the older nuclear power plants to comply with the break preclusion concept. Also a number of extensions of the concept have been developed to cover also leak-assumptions for branch pipes. Furthermore due considerations have been given to other aspects which could contribute to a leak development in the primary circuit, like vessel penetrations, manhole covers, flanges, etc. Now the break preclusion concept originally applied to the main piping has been developed into an integrated concept for the whole pressure boundary within the containment and will be applied also in the periodic safety review of present nuclear power plants.« less

Radical Chemistry and Charge Manipulation with an Atomic Force Microscope

NASA Astrophysics Data System (ADS)

Gross, Leo

The fuctionalization of tips by atomic manipulation dramatically increased the resolution of atomic force microscopy (AFM). The combination of high-resolution AFM with atomic manipulation now offers the unprecedented possibility to custom-design individual molecules by making and breaking bonds with the tip of the microscope and directly characterizing the products on the atomic scale. We recently applied this technique to generate and study reaction intermediates and to investigate chemical reactions trigged by atomic manipulation. We formed diradicals by dissociating halogen atoms and then reversibly triggered ring-opening and -closing reactions via atomic manipulation, allowing us to switch and control the molecule's reactivity, magnetic and optical properties. Additional information about charge states and charge distributions can be obtained by Kelvin probe force spectroscopy. On multilayer insulating films we investigated single-electron attachment, detachment and transfer between individual molecules. EU ERC AMSEL (682144), EU project PAMS (610446).

Gravitational Microlensing Observations of Two New Exoplanets Using the Deep Impact High Resolution Instrument

NASA Astrophysics Data System (ADS)

Barry, Richard K.; Bennett, D. P.; Klaasen, K.; Becker, A. C.; Christiansen, J.; Albrow, M.

2014-01-01

We have worked to characterize two exoplanets newly detected from the ground: OGLE-2012-BLG-0406 and OGLE-2012-BLG-0838, using microlensing observations of the Galactic Bulge recently obtained by NASA’s Deep Impact (DI) spacecraft, in combination with ground data. These observations of the crowded Bulge fields from Earth and from an observatory at a distance of ~1 AU have permitted the extraction of a microlensing parallax signature - critical for breaking exoplanet model degeneracies. For this effort, we used DI’s High Resolution Instrument, launched with a permanent defocus aberration due to an error in cryogenic testing. We show how the effects of a very large, chromatic PSF can be reduced in differencing photometry. We also compare two approaches to differencing photometry - one of which employs the Bramich algorithm and another using the Fruchter & Hook drizzle algorithm.

SOLAR WIND TURBULENCE FROM MHD TO SUB-ION SCALES: HIGH-RESOLUTION HYBRID SIMULATIONS

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

Franci, Luca; Verdini, Andrea; Landi, Simone

2015-05-10

We present results from a high-resolution and large-scale hybrid (fluid electrons and particle-in-cell protons) two-dimensional numerical simulation of decaying turbulence. Two distinct spectral regions (separated by a smooth break at proton scales) develop with clear power-law scaling, each one occupying about a decade in wavenumbers. The simulation results simultaneously exhibit several properties of the observed solar wind fluctuations: spectral indices of the magnetic, kinetic, and residual energy spectra in the magnetohydrodynamic (MHD) inertial range along with a flattening of the electric field spectrum, an increase in magnetic compressibility, and a strong coupling of the cascade with the density and themore » parallel component of the magnetic fluctuations at sub-proton scales. Our findings support the interpretation that in the solar wind, large-scale MHD fluctuations naturally evolve beyond proton scales into a turbulent regime that is governed by the generalized Ohm’s law.« less

Solar Wind Turbulence from MHD to Sub-ion Scales: High-resolution Hybrid Simulations

NASA Astrophysics Data System (ADS)

Franci, Luca; Verdini, Andrea; Matteini, Lorenzo; Landi, Simone; Hellinger, Petr

2015-05-01

We present results from a high-resolution and large-scale hybrid (fluid electrons and particle-in-cell protons) two-dimensional numerical simulation of decaying turbulence. Two distinct spectral regions (separated by a smooth break at proton scales) develop with clear power-law scaling, each one occupying about a decade in wavenumbers. The simulation results simultaneously exhibit several properties of the observed solar wind fluctuations: spectral indices of the magnetic, kinetic, and residual energy spectra in the magnetohydrodynamic (MHD) inertial range along with a flattening of the electric field spectrum, an increase in magnetic compressibility, and a strong coupling of the cascade with the density and the parallel component of the magnetic fluctuations at sub-proton scales. Our findings support the interpretation that in the solar wind, large-scale MHD fluctuations naturally evolve beyond proton scales into a turbulent regime that is governed by the generalized Ohm’s law.

A high spatial resolution X-ray and Hα study of hot gas in the halos of star-forming disk galaxies -- testing feedback models

NASA Astrophysics Data System (ADS)

Strickland, D. K.; Heckman, T. M.; Colbert, E. J. M.; Hoopes, C. G.; Weaver, K. A.

2002-12-01

We present arcsecond resolution Chandra X-ray and ground-based optical Hα imaging of a sample of ten edge-on star-forming disk galaxies (seven starburst and three ``normal'' spiral galaxies), a sample which covers the full range of star-formation intensity found in disk galaxies. The X-ray observations make use of the unprecented spatial resolution of the Chandra X-ray observatory to robustly remove X-ray emission from point sources, and hence obtain the X-ray properties of the diffuse thermal emission alone. This data has been combined with existing, comparable-resolution, ground-based Hα imaging. We compare these empirically-derived diffuse X-ray properties with various models for the generation of hot gas in the halos of star-forming galaxies: supernova feedback-based models (starburst-driven winds, galactic fountains), cosmologically-motivated accretion of the IGM and AGN-driven winds. SN feedback models best explain the observed diffuse X-ray emission. We then use the data to test basic, but fundamental, aspects of wind and fountain theories, e.g. the critical energy required for disk "break-out." DKS is supported by NASA through Chandra Postdoctoral Fellowship Award Number PF0-10012.

A survey and assessment of the capabilities of Cubesats for Earth observation

NASA Astrophysics Data System (ADS)

Selva, Daniel; Krejci, David

2012-05-01

In less than a decade, Cubesats have evolved from purely educational tools to a standard platform for technology demonstration and scientific instrumentation. The use of COTS (Commercial-Off-The-Shelf) components and the ongoing miniaturization of several technologies have already led to scattered instances of missions with promising scientific value. Furthermore, advantages in terms of development cost and development time with respect to larger satellites, as well as the possibility of launching several dozens of Cubesats with a single rocket launch, have brought forth the potential for radically new mission architectures consisting of very large constellations or clusters of Cubesats. These architectures promise to combine the temporal resolution of GEO missions with the spatial resolution of LEO missions, thus breaking a traditional trade-off in Earth observation mission design. This paper assesses the current capabilities of Cubesats with respect to potential employment in Earth observation missions. A thorough review of Cubesat bus technology capabilities is performed, identifying potential limitations and their implications on 17 different Earth observation payload technologies. These results are matched to an exhaustive review of scientific requirements in the field of Earth observation, assessing the possibilities of Cubesats to cope with the requirements set for each one of 21 measurement categories. Based on this review, several Earth observation measurements are identified that can potentially be compatible with the current state-of-the-art of Cubesat technology although some of them have actually never been addressed by any Cubesat mission. Simultaneously, other measurements are identified which are unlikely to be performed by Cubesats in the next few years due to insuperable constraints. Ultimately, this paper is intended to supply a box of ideas for universities to design future Cubesat missions with high scientific payoff.

Development of Vertical Cable Seismic System for Hydrothermal Deposit Survey (2) - Feasibility Study

NASA Astrophysics Data System (ADS)

Asakawa, E.; Murakami, F.; Sekino, Y.; Okamoto, T.; Mikada, H.; Takekawa, J.; Shimura, T.

2010-12-01

In 2009, Ministry of Education, Culture, Sports, Science and Technology(MEXT) started the survey system development for Hydrothermal deposit. We proposed the Vertical Cable Seismic (VCS), the reflection seismic survey with vertical cable above seabottom. VCS has the following advantages for hydrothermal deposit survey. . (1) VCS is an effective high-resolution 3D seismic survey within limited area. (2) It achieves high-resolution image because the sensors are closely located to the target. (3) It avoids the coupling problems between sensor and seabottom that cause serious damage of seismic data quality. (4) Various types of marine source are applicable with VCS such as sea-surface source (air gun, water gun etc.) , deep-towed or ocean bottom sources. (5) Autonomous recording system. Our first experiment of 2D/3D VCS surveys has been carried out in Lake Biwa, JAPAN. in November 2009. The 2D VCS data processing follows the walk-away VSP, including wave field separation and depth migration. The result gives clearer image than the conventional surface seismic. Prestack depth migration is applied to 3D data to obtain good quality 3D depth volume. Uncertainty of the source/receiver poisons in water causes the serious problem of the imaging. We used several transducer/transponder to estimate these positions. The VCS seismic records themselves can also provide sensor position using the first break of each trace and we calibrate the positions. We are currently developing the autonomous recording VCS system and planning the trial experiment in actual ocean to establish the way of deployment/recovery and the examine the position through the current flow in November, 2010. The second VCS survey will planned over the actual hydrothermal deposit with deep-towed source in February, 2011.

Predictive value of routine esophageal high-resolution manometry for gastro-esophageal reflux disease.

PubMed

van Hoeij, F B; Smout, A J; Bredenoord, A J

2015-07-01

Using conventional manometry, gastro-esophageal reflux disease (GERD) was associated with a reduced lower esophageal sphincter (LES) pressure and impaired peristalsis. However, with a large overlap between GERD patients and controls, these findings are of limited clinical relevance. It is uncertain whether the more detailed information of high-resolution manometry (HRM) can discriminate GERD patients. Therefore, we aimed to determine to which extent HRM findings can predict GERD. HRM measurements in 69 patients with GERD and 40 healthy subjects were compared and the predictive value of HRM for the diagnosis of GERD was explored. GERD patients had a significantly lower contraction amplitude (55 vs 64 mmHg; p = 0.045) and basal LES pressure (10 vs 13.2 mmHg; p = 0.034) than healthy controls. GERD patients more often had a hiatal hernia than healthy subjects (30% vs 7%; p = 0.005). Patients with reflux esophagitis had a lower DCI than patients without reflux esophagitis (558 vs 782 mmHg cm s; p = 0.045). No significant difference was seen in contractile front velocity, distal latency, number of peristaltic breaks, residual LES pressure and LES length. On multivariate logistic regression analysis, both esophagogastric junction type I (OR 4.971; 95% CI 1.33-18.59; p = 0.017) and mean wave amplitude (OR 0.95; 95% CI 0.90-0.98; p = 0.013) were found to be independent predictors of GERD. However, the sensitivity and specificity of these findings were low. Hiatal hernia, low contraction amplitude and LES pressure are associated with GERD, but do not predict the disease with sufficient accuracy. Routine esophageal HRM can therefore not be used to distinguish GERD patients from healthy subjects. © 2015 John Wiley & Sons Ltd.

BLISS is a versatile and quantitative method for genome-wide profiling of DNA double-strand breaks.

PubMed

Yan, Winston X; Mirzazadeh, Reza; Garnerone, Silvano; Scott, David; Schneider, Martin W; Kallas, Tomasz; Custodio, Joaquin; Wernersson, Erik; Li, Yinqing; Gao, Linyi; Federova, Yana; Zetsche, Bernd; Zhang, Feng; Bienko, Magda; Crosetto, Nicola

2017-05-12

Precisely measuring the location and frequency of DNA double-strand breaks (DSBs) along the genome is instrumental to understanding genomic fragility, but current methods are limited in versatility, sensitivity or practicality. Here we present Breaks Labeling In Situ and Sequencing (BLISS), featuring the following: (1) direct labelling of DSBs in fixed cells or tissue sections on a solid surface; (2) low-input requirement by linear amplification of tagged DSBs by in vitro transcription; (3) quantification of DSBs through unique molecular identifiers; and (4) easy scalability and multiplexing. We apply BLISS to profile endogenous and exogenous DSBs in low-input samples of cancer cells, embryonic stem cells and liver tissue. We demonstrate the sensitivity of BLISS by assessing the genome-wide off-target activity of two CRISPR-associated RNA-guided endonucleases, Cas9 and Cpf1, observing that Cpf1 has higher specificity than Cas9. Our results establish BLISS as a versatile, sensitive and efficient method for genome-wide DSB mapping in many applications.

Symmetry-breaking dynamics of the finite-size Lipkin-Meshkov-Glick model near ground state

NASA Astrophysics Data System (ADS)

Huang, Yi; Li, Tongcang; Yin, Zhang-qi

2018-01-01

We study the dynamics of the Lipkin-Meshkov-Glick (LMG) model with a finite number of spins. In the thermodynamic limit, the ground state of the LMG model with an isotropic Hamiltonian in the broken phase breaks to a mean-field ground state with a certain direction. However, when the spin number N is finite, the exact ground state is always unique and is not given by a classical mean-field ground state. Here, we prove that when N is large but finite, through a tiny external perturbation, a localized state which is close to a mean-field ground state can be prepared, which mimics spontaneous symmetry breaking. Also, we find the localized in-plane spin polarization oscillates with two different frequencies ˜O (1 /N ) , and the lifetime of the localized state is long enough to exhibit this oscillation. We numerically test the analytical results and find that they agree very well with each other. Finally, we link the phenomena to quantum time crystals and time quasicrystals.

Music and Video Gaming during Breaks: Influence on Habitual versus Goal-Directed Decision Making.

PubMed

Liu, Shuyan; Schad, Daniel J; Kuschpel, Maxim S; Rapp, Michael A; Heinz, Andreas

2016-01-01

Different systems for habitual versus goal-directed control are thought to underlie human decision-making. Working memory is known to shape these decision-making systems and their interplay, and is known to support goal-directed decision making even under stress. Here, we investigated if and how decision systems are differentially influenced by breaks filled with diverse everyday life activities known to modulate working memory performance. We used a within-subject design where young adults listened to music and played a video game during breaks interleaved with trials of a sequential two-step Markov decision task, designed to assess habitual as well as goal-directed decision making. Based on a neurocomputational model of task performance, we observed that for individuals with a rather limited working memory capacity video gaming as compared to music reduced reliance on the goal-directed decision-making system, while a rather large working memory capacity prevented such a decline. Our findings suggest differential effects of everyday activities on key decision-making processes.

Chromosome integrity at a double-strand break requires exonuclease 1 and MRX

PubMed Central

Nakai, Wataru; Westmoreland, Jim; Yeh, Elaine; Bloom, Kerry; Resnick, Michael A.

2010-01-01

The continuity of duplex DNA is generally considered a prerequisite for chromosome continuity. However, as previously shown in yeast as well as human cells, the introduction of a double-strand break (DSB) does not generate a chromosome break (CRB) in yeast or human cells. The transition from DSB to CRB was found to be under limited control by the tethering function of the RAD50/MRE11/XRS2 (MRX) complex. Using a system for differential fluorescent marking of both sides of an endonuclease-induced DSB in single cells, we found that nearly all DSBs are converted to CRBs in cells lacking both exonuclease 1 (EXO1) activity and MRX complex. Thus, it appears that some feature of exonuclease processing or resection at a DSB is critical for maintaining broken chromosome ends in close proximity. In addition, we discovered a thermal sensitive (cold) component to CRB formation in an MRX mutant that has implications for chromosome end mobility and/or end-processing. PMID:21115410

Effect of thermoplastic polyurethane (TPU) on the thermal and mechanical properties of polylactic acid (PLA)/curcumin blends

NASA Astrophysics Data System (ADS)

Sharifah, I. S. S.; Adnan, M. D. A.; Nor Khairusshima, M. K.; Shaffiar, N. M.; Buys, Y. F.

2018-01-01

Polylactic acid (PLA) is known to be brittle by nature and thus limits the flexibility of the polymer. A possible solution to enhance the flexibility of PLA is to add a flexible polymeric based material such as thermoplastic polyurethane (TPU). In this study, 30-50 wt% of TPU was added into PLA/curcumin blends to improve its flexibility. Thermal analysis using differential scanning calorimetry shows that further additions of TPU at the expense of PLA did not affect the glass transition temperature, crystallisation temperature and melting temperature of the blends. Fibers of PLA/curcumin/TPU were successfully drawn and Single Fiber Tensile Test (SFTT) showed vast improvement in elongation at break. The initial addition of 30 wt% of TPU to the brittle PLA/curcumin composition causes a significant increase in elongation at break by 39 times and further additions at 50 wt %, the elongation at break increases by 105 times. However, with the increase in elongation, a decrease in strength and Young’s modulus was observed.

Music and Video Gaming during Breaks: Influence on Habitual versus Goal-Directed Decision Making

PubMed Central

Kuschpel, Maxim S.; Rapp, Michael A.; Heinz, Andreas

2016-01-01

Different systems for habitual versus goal-directed control are thought to underlie human decision-making. Working memory is known to shape these decision-making systems and their interplay, and is known to support goal-directed decision making even under stress. Here, we investigated if and how decision systems are differentially influenced by breaks filled with diverse everyday life activities known to modulate working memory performance. We used a within-subject design where young adults listened to music and played a video game during breaks interleaved with trials of a sequential two-step Markov decision task, designed to assess habitual as well as goal-directed decision making. Based on a neurocomputational model of task performance, we observed that for individuals with a rather limited working memory capacity video gaming as compared to music reduced reliance on the goal-directed decision-making system, while a rather large working memory capacity prevented such a decline. Our findings suggest differential effects of everyday activities on key decision-making processes. PMID:26982326

Parity-time symmetry breaking in magnetic systems

DOE PAGES

Galda, Alexey; Vinokur, Valerii M.

2016-07-14

The understanding of out-of-equilibrium physics, especially dynamic instabilities and dynamic phase transitions, is one of the major challenges of contemporary science, spanning the broadest wealth of research areas that range from quantum optics to living organisms. By focusing on nonequilibrium dynamics of an open dissipative spin system, we introduce a non-Hermitian Hamiltonian approach, in which non-Hermiticity reflects dissipation and deviation from equilibrium. The imaginary part of the proposed spin Hamiltonian describes the effects of Gilbert damping and applied Slonczewski spin-transfer torque. In the classical limit, our approach reproduces Landau-Lifshitz-Gilbert-Slonczewski dynamics of a large macrospin. Here, we reveal the spin-transfer torque-drivenmore » parity-time symmetry-breaking phase transition corresponding to a transition from precessional to exponentially damped spin dynamics. Micromagnetic simulations for nanoscale ferromagnetic disks demonstrate the predicted effect. These findings can pave the way to a general quantitative description of out-of-equilibrium phase transitions driven by spontaneous parity-time symmetry breaking.« less

Optical mapping of Langendorff-perfused human hearts: establishing a model for the study of ventricular fibrillation in humans.

PubMed

Nanthakumar, Kumaraswamy; Jalife, José; Massé, Stéphane; Downar, Eugene; Pop, Mihaela; Asta, John; Ross, Heather; Rao, Vivek; Mironov, Sergey; Sevaptsidis, Elias; Rogers, Jack; Wright, Graham; Dhopeshwarkar, Rajesh

2007-07-01

Our objective was to establish a novel model for the study of ventricular fibrillation (VF) in humans. We adopted the established techniques of optical mapping to human ventricles for the first time to determine whether human VF is the result of wave breaks and singularity point formation and is maintained by high-frequency rotors and fibrillatory conduction. We describe the technique of acquiring optical signals in human hearts during VF, their characteristics, and the feasibility of possible analyses that could be performed to elucidate mechanisms of human VF. We used explanted hearts from five cardiomyopathic patients who underwent transplantation. The hearts were Langendorff perfused with Tyrode solution (95% O(2)-5% CO(2)), and the potentiometric dye di-4-ANEPPS was injected as a bolus into the coronary circulation. Fluorescence was excited at 531 +/- 20 nm with a 150-W halogen light source; the emission signal was long-pass filtered at 610 nm and recorded with a mapping camera. Fractional change of fluorescence varied between 2% and 12%. Average signal-to-noise ratio was 40 dB. The mean velocity of VF wave fronts was 0.25 +/- 0.04 m/s. Submillimetric spatial resolution (0.65-0.85 mm), activation mapping, and transformation of the data to phase-based analysis revealed reentrant, colliding, and fractionating wave fronts in human VF. On many occasions the VF wave fronts were as large as the entire vertical length (8 cm) of the mapping field, suggesting that there are a limited number of wave fronts on the human heart during VF. Phase transformation of the optical signals allowed the first demonstration ever of phase singularity point, wave breaks, and rotor formation in human VF. This method provides opportunities for potential analyses toward elucidation of the mechanisms of VF and defibrillation in humans.

Epsilon-near-Zero Metamaterial to break the FRET distance barrier

NASA Astrophysics Data System (ADS)

Deshmukh, Rahul; Biehs, Svend-Age; Khwaja, Emaad; Agarwal, Girish; Menon, Vinod

Forster Resonance Energy Transfer (FRET) in a donor acceptor pair is a tool widely used as a spectroscopic ruler in biology and related fields. The high sensitivity to distance change in this technique comes at the expense of limitation on the spatial range (10nm) that can be measured. Here we present an alternate approach where the epsilon-near-zero (EnZ) regime in a metamaterial is used to break the FRET distance limit. We show long range (160nm) energy transfer in a donor acceptor pair across the EnZ metamaterial as proof-of-principle. This scheme can be implemented for any donor acceptor pair by tailoring the metal fill-fraction in the metamaterial design appropriately. The experimental data includes change in donor lifetimes as well as increase in the steady state emission of the acceptor. We also show theoretical simulations which suggest that the EnZ regime is the most effective in mediating such long-range energy transfer as compared to Hyperbolic/Elliptical regimes in metamaterials. NSF DMR 1410249.

2D negative capacitance field-effect transistor with organic ferroelectrics.

PubMed

Zhang, Heng; Chen, Yan; Ding, Shijin; Wang, Jianlu; Bao, Wenzhong; Zhang, David Wei; Zhou, Peng

2018-06-15

In the past fifty years, complementary metal-oxide-semiconductor integrated circuits have undergone significant development, but Moore's law will soon come to an end. In order to break through the physical limit of Moore's law, 2D materials have been widely used in many electronic devices because of their high mobility and excellent mechanical flexibility. And the emergence of a negative capacitance field-effect transistor (NCFET) could not only break the thermal limit of conventional devices, but reduce the operating voltage and power consumption. This paper demonstrates a 2D NCFET that treats molybdenum disulfide as a channel material and organic P(VDF-TrFE) as a gate dielectric directly. This represents a new attempt to prepare NCFETs and produce flexible electronic devices. It exhibits a 10^6 on-/off-current ratio. And the minimum subthreshold swing (SS) of the 21 mV/decade and average SS of the 44 mV/decade in four orders of magnitude of drain current can also be observed at room temperature of 300 K.

2D negative capacitance field-effect transistor with organic ferroelectrics

NASA Astrophysics Data System (ADS)

Zhang, Heng; Chen, Yan; Ding, Shijin; Wang, Jianlu; Bao, Wenzhong; Zhang, David Wei; Zhou, Peng

2018-06-01

In the past fifty years, complementary metal-oxide-semiconductor integrated circuits have undergone significant development, but Moore’s law will soon come to an end. In order to break through the physical limit of Moore’s law, 2D materials have been widely used in many electronic devices because of their high mobility and excellent mechanical flexibility. And the emergence of a negative capacitance field-effect transistor (NCFET) could not only break the thermal limit of conventional devices, but reduce the operating voltage and power consumption. This paper demonstrates a 2D NCFET that treats molybdenum disulfide as a channel material and organic P(VDF-TrFE) as a gate dielectric directly. This represents a new attempt to prepare NCFETs and produce flexible electronic devices. It exhibits a 106 on-/off-current ratio. And the minimum subthreshold swing (SS) of the 21 mV/decade and average SS of the 44 mV/decade in four orders of magnitude of drain current can also be observed at room temperature of 300 K.

Can quantum coherent solar cells break detailed balance?

NASA Astrophysics Data System (ADS)

Kirk, Alexander P.

2015-07-01

Carefully engineered coherent quantum states have been proposed as a design attribute that is hypothesized to enable solar photovoltaic cells to break the detailed balance (or radiative) limit of power conversion efficiency by possibly causing radiative recombination to be suppressed. However, in full compliance with the principles of statistical mechanics and the laws of thermodynamics, specially prepared coherent quantum states do not allow a solar photovoltaic cell—a quantum threshold energy conversion device—to exceed the detailed balance limit of power conversion efficiency. At the condition given by steady-state open circuit operation with zero nonradiative recombination, the photon absorption rate (or carrier photogeneration rate) must balance the photon emission rate (or carrier radiative recombination rate) thus ensuring that detailed balance prevails. Quantum state transitions, entropy-generating hot carrier relaxation, and photon absorption and emission rate balancing are employed holistically and self-consistently along with calculations of current density, voltage, and power conversion efficiency to explain why detailed balance may not be violated in solar photovoltaic cells.

Breaking the limitation of mode building time in an optoelectronic oscillator.

PubMed

Hao, Tengfei; Cen, Qizhuang; Dai, Yitang; Tang, Jian; Li, Wei; Yao, Jianping; Zhu, Ninghua; Li, Ming

2018-05-09

An optoelectronic oscillator (OEO) is a microwave photonic system with a positive feedback loop used to create microwave oscillation with ultra-low phase noise thanks to the employment of a high-quality-factor energy storage element, such as a fiber delay line. For many applications, a frequency-tunable microwave signal or waveform, such as a linearly chirped microwave waveform (LCMW), is also needed. Due to the long characteristic time constant required for building up stable oscillation at an oscillation mode, it is impossible to generate an LCMW with a large chirp rate using a conventional frequency-tunable OEO. In this study, we propose and demonstrate a new scheme to generate a large chirp-rate LCMW based on Fourier domain mode locking technique to break the limitation of mode building time in an OEO. An LCMW with a high chirp rate of 0.34 GHz/μs and a large time-bandwidth product of 166,650 is demonstrated.

Camera system resolution and its influence on digital image correlation

DOE PAGES

Reu, Phillip L.; Sweatt, William; Miller, Timothy; ...

2014-09-21

Digital image correlation (DIC) uses images from a camera and lens system to make quantitative measurements of the shape, displacement, and strain of test objects. This increasingly popular method has had little research on the influence of the imaging system resolution on the DIC results. This paper investigates the entire imaging system and studies how both the camera and lens resolution influence the DIC results as a function of the system Modulation Transfer Function (MTF). It will show that when making spatial resolution decisions (including speckle size) the resolution limiting component should be considered. A consequence of the loss ofmore » spatial resolution is that the DIC uncertainties will be increased. This is demonstrated using both synthetic and experimental images with varying resolution. The loss of image resolution and DIC accuracy can be compensated for by increasing the subset size, or better, by increasing the speckle size. The speckle-size and spatial resolution are now a function of the lens resolution rather than the more typical assumption of the pixel size. The study will demonstrate the tradeoffs associated with limited lens resolution.« less

Speckle imaging for planetary research

NASA Technical Reports Server (NTRS)

Nisenson, P.; Goody, R.; Apt, J.; Papaliolios, C.

1983-01-01

The present study of speckle imaging technique effectiveness encompasses image reconstruction by means of a division algorithm for Fourier amplitudes, and the Knox-Thompson (1974) algorithm for Fourier phases. Results which have been obtained for Io, Titan, Pallas, Jupiter and Uranus indicate that spatial resolutions lower than the seeing limit by a factor of four are obtainable for objects brighter than Uranus. The resolutions obtained are well above the diffraction limit, due to inadequacies of the video camera employed. A photon-counting camera has been developed to overcome these difficulties, making possible the diffraction-limited resolution of objects as faint as Charon.

Limits to magnetic resonance microscopy

NASA Astrophysics Data System (ADS)

Glover, Paul; Mansfield, Peter, Sir

2002-10-01

The last quarter of the twentieth century saw the development of magnetic resonance imaging (MRI) grow from a laboratory demonstration to a multi-billion dollar worldwide industry. There is a clinical body scanner in almost every hospital of the developed nations. The field of magnetic resonance microscopy (MRM), after mostly being abandoned by researchers in the first decade of MRI, has become an established branch of the science. This paper reviews the development of MRM over the last decade with an emphasis on the current state of the art. The fundamental principles of imaging and signal detection are examined to determine the physical principles which limit the available resolution. The limits are discussed with reference to liquid, solid and gas phase microscopy. In each area, the novel approaches employed by researchers to push back the limits of resolution are discussed. Although the limits to resolution are well known, the developments and applications of MRM have not reached their limit.

Motivation and intention to integrate physical activity into daily school life: the JAM World Record event.

PubMed

Vazou, Spyridoula; Vlachopoulos, Symeon P

2014-11-01

Research on the motivation of stakeholders to integrate physical activity into daily school life is limited. The purpose was to examine the motivation of stakeholders to participate in a world record physical activity event and whether motivation was associated with future intention to use activity breaks during the daily school life and future participation in a similar event. After the 2012 JAM (Just-a-Minute) World Record event, 686 adults (591 women; 76.1% participated for children <10 years) completed measures of motivational regulations and future intention to (a) use the activity breaks and (b) participate in the event. High intrinsic motivation and low extrinsic motivation and amotivation for participation in the next event were reported. Hierarchical regression analysis, controlling for age, gender, and occupation, showed that intrinsic forms of motivation positively predicted, whereas amotivation negatively predicted, future intention to participate in the event and use the activity breaks. Multivariate analyses of variance revealed that school-related participants were more intrinsically motivated and intended to use the activity breaks and repeat the event more than those who were not affiliated with a school. Nonschool participants reported higher extrinsic motivation and amotivation than school-related participants. © 2014 Society for Public Health Education.

["Truth at the bedside"--continuing medical education and breaking bad news].

PubMed

Schildmann, Jan; Herrmann, Eva; Klambeck, Amelie; Ortwein, Heiderose; Schwarz, Carsten; Vollmann, Jochen

2005-01-01

Discussions with seriously-ill patients are part of the physicians' tasks. These discussions demand good communication skills. In this paper we present the concept of a postgraduate course for physicians on ethics and breaking bad news, as well as the results of the course evaluation. Questionnaire distributed before and immediately after the course using closed-ended questions and Likert scales. 37 physicians (response rate: 84.1%) from seven specialties completed the questionnaires. Twenty-eight respondents (75.6%) had been involved in breaking bad news more than 5 times per month. Approximately half of the respondents (N = 18; 48.6%) rated the discussions on the limits of curative treatment as particularly difficult communication situations. With one exception, all physicians denied the existence of guidelines on breaking bad news in their institutions. Compared with the beginning of the course, the respondents rated their communication skills to be improved at the end of the course. Positive evaluations were obtained for practice relevance, teaching methods, and organisation of the course. The interest in this optional postgraduate course and the feedback of the participants indicate the necessity of professional training on difficult communication situations. The self-rating of improved communication skills may be interpreted as a positive effect of the course. Observational studies are required to confirm the effects of the training.

Quantifying Wave Breaking Shape and Type in the Surf-Zone Using LiDAR

NASA Astrophysics Data System (ADS)

Albright, A.; Brodie, K. L.; Hartzell, P. J.; Glennie, C. L.

2017-12-01

Waves change shape as they shoal and break across the surf-zone, ultimately dissipating and transferring their energy into turbulence by either spilling or plunging. This injection of turbulence and changes in wave shape can affect the direction of sediment transport at the seafloor, and ultimately lead to morphological evolution. Typical methods for collecting wave data in the surf-zone include in-situ pressure gauges, velocimeters, ultrasonic sensors, and video imagery. Drawbacks to these data collection methods are low spatial resolution of point measurements, reliance on linear theory to calculate sea-surface elevations, and intensive computations required to extract wave properties from stereo 2D imagery. As a result, few field measurements of the shapes of plunging and/or spilling breakers exist, and existing knowledge is confined to results of laboratory studies. We therefore examine the use of a multi-beam scanning Light Detection and Ranging (LiDAR) remote sensing instrument with the goal of classifying the breaking type of propagating waves in the surf-zone and quantitatively determining wave morphometric properties. Data were collected with a Velodyne HDL-32E LiDAR scanner (360° vertical field of view) mounted on an arm of the Coastal Research Amphibious Buggy (CRAB) at the U.S. Army Corps of Engineers Field Research Facility in Duck, North Carolina. Processed laser scan data are used to visualize the lifecycle of a wave (shoaling, breaking, broken) and identify wave types (spilling, plunging, non-breaking) as they pass beneath the scanner. For each rotation of the LiDAR scanner, the point cloud data are filtered, smoothed, and detrended in order to identify individual waves and measure their properties, such as speed, height, period, upward/downward slope, asymmetry, and skewness. The 3D nature of point cloud data is advantageous for research, because it enables viewing from any angle. In our analysis, plan views are used to separate individual waves, and cross-shore profiles are used to extract wave properties. Combined with accurate georeferencing information, LiDAR has the potential to be a powerful remote sensing tool for coastal monitoring systems and the study of nearshore processes.

Adaptive optics and interferometry

NASA Technical Reports Server (NTRS)

Beichman, Charles A.; Ridgway, Stephen

1991-01-01

Adaptive optics and interferometry, two techniques that will improve the limiting resolution of optical and infrared observations by factors of tens or even thousands, are discussed. The real-time adjustment of optical surfaces to compensate for wavefront distortions will improve image quality and increase sensitivity. The phased operation of multiple telescopes separated by large distances will make it possible to achieve very high angular resolution and precise positional measurements. Infrared and optical interferometers that will manipulate light beams and measure interference directly are considered. Angular resolutions of single telescopes will be limited to around 10 milliarcseconds even using the adaptive optics techniques. Interferometry would surpass this limit by a factor of 100 or more. Future telescope arrays with 100-m baselines (resolution of 2.5 milliarcseconds at a 1-micron wavelength) are also discussed.

Optical analysis of a compound quasi-microscope for planetary landers

NASA Technical Reports Server (NTRS)

Wall, S. D.; Burcher, E. E.; Huck, F. O.

1974-01-01

A quasi-microscope concept, consisting of facsimile camera augmented with an auxiliary lens as a magnifier, was introduced and analyzed. The performance achievable with this concept was primarily limited by a trade-off between resolution and object field; this approach leads to a limiting resolution of 20 microns when used with the Viking lander camera (which has an angular resolution of 0.04 deg). An optical system is analyzed which includes a field lens between camera and auxiliary lens to overcome this limitation. It is found that this system, referred to as a compound quasi-microscope, can provide improved resolution (to about 2 microns ) and a larger object field. However, this improvement is at the expense of increased complexity, special camera design requirements, and tighter tolerances on the distances between optical components.

Bayesian superresolution

NASA Astrophysics Data System (ADS)

Isakson, Steve Wesley

2001-12-01

Well-known principles of physics explain why resolution restrictions occur in images produced by optical diffraction-limited systems. The limitations involved are present in all diffraction-limited imaging systems, including acoustical and microwave. In most circumstances, however, prior knowledge about the object and the imaging system can lead to resolution improvements. In this dissertation I outline a method to incorporate prior information into the process of reconstructing images to superresolve the object beyond the above limitations. This dissertation research develops the details of this methodology. The approach can provide the most-probable global solution employing a finite number of steps in both far-field and near-field images. In addition, in order to overcome the effects of noise present in any imaging system, this technique provides a weighted image that quantifies the likelihood of various imaging solutions. By utilizing Bayesian probability, the procedure is capable of incorporating prior information about both the object and the noise to overcome the resolution limitation present in many imaging systems. Finally I will present an imaging system capable of detecting the evanescent waves missing from far-field systems, thus improving the resolution further.

Using domain knowledge and domain-inspired discourse model for coreference resolution for clinical narratives

PubMed Central

Roth, Dan

2013-01-01

Objective This paper presents a coreference resolution system for clinical narratives. Coreference resolution aims at clustering all mentions in a single document to coherent entities. Materials and methods A knowledge-intensive approach for coreference resolution is employed. The domain knowledge used includes several domain-specific lists, a knowledge intensive mention parsing, and task informed discourse model. Mention parsing allows us to abstract over the surface form of the mention and represent each mention using a higher-level representation, which we call the mention's semantic representation (SR). SR reduces the mention to a standard form and hence provides better support for comparing and matching. Existing coreference resolution systems tend to ignore discourse aspects and rely heavily on lexical and structural cues in the text. The authors break from this tradition and present a discourse model for “person” type mentions in clinical narratives, which greatly simplifies the coreference resolution. Results This system was evaluated on four different datasets which were made available in the 2011 i2b2/VA coreference challenge. The unweighted average of F1 scores (over B-cubed, MUC and CEAF) varied from 84.2% to 88.1%. These experiments show that domain knowledge is effective for different mention types for all the datasets. Discussion Error analysis shows that most of the recall errors made by the system can be handled by further addition of domain knowledge. The precision errors, on the other hand, are more subtle and indicate the need to understand the relations in which mentions participate for building a robust coreference system. Conclusion This paper presents an approach that makes an extensive use of domain knowledge to significantly improve coreference resolution. The authors state that their system and the knowledge sources developed will be made publicly available. PMID:22781192

Low-cost, high-resolution scanning laser ophthalmoscope for the clinical environment

NASA Astrophysics Data System (ADS)

Soliz, P.; Larichev, A.; Zamora, G.; Murillo, S.; Barriga, E. S.

2010-02-01

Researchers have sought to gain greater insight into the mechanisms of the retina and the optic disc at high spatial resolutions that would enable the visualization of small structures such as photoreceptors and nerve fiber bundles. The sources of retinal image quality degradation are aberrations within the human eye, which limit the achievable resolution and the contrast of small image details. To overcome these fundamental limitations, researchers have been applying adaptive optics (AO) techniques to correct for the aberrations. Today, deformable mirror based adaptive optics devices have been developed to overcome the limitations of standard fundus cameras, but at prices that are typically unaffordable for most clinics. In this paper we demonstrate a clinically viable fundus camera with auto-focus and astigmatism correction that is easy to use and has improved resolution. We have shown that removal of low-order aberrations results in significantly better resolution and quality images. Additionally, through the application of image restoration and super-resolution techniques, the images present considerably improved quality. The improvements lead to enhanced visualization of retinal structures associated with pathology.

On the possibility of observing bound soliton pairs in a wave-breaking-free mode-locked fiber laser

NASA Astrophysics Data System (ADS)

Martel, G.; Chédot, C.; Réglier, V.; Hideur, A.; Ortaç, B.; Grelu, Ph.

2007-02-01

On the basis of numerical simulations, we explain the formation of the stable bound soliton pairs that were experimentally reported in a high-power mode-locked ytterbium fiber laser [Opt. Express 14, 6075 (2006)], in a regime where wave-breaking-free operation is expected. A fully vectorial model allows one to rigorously reproduce the nonmonotonic nature for the nonlinear polarization effect that generally limits the power scalability of a single-pulse self-similar regime. Simulations show that a self-similar regime is not fully obtained, although positive linear chirps and parabolic spectra are always reported. As a consequence, nonvanishing pulse tails allow distant stable binding of highly-chirped pulses.

Statistical properties of fractures in damaged materials

NASA Astrophysics Data System (ADS)

Gabrielli, A.; Cafiero, R.; Caldarelli, G.

1999-01-01

We introduce a model for the dynamics of mud cracking in the limit of of extremely thin layers. In this model the growth of fracture proceeds by selecting the part of the material with the smallest (quenched) breaking threshold. In addition, weakening affects the area of the sample neighbour to the crack. Due to the simplicity of the model, it is possible to derive some analytical results. In particular, we find that the total time to break down the sample grows with the dimension L of the lattice as L2 even though the percolating cluster has a non-trivial fractal dimension. Furthermore, we obtain a formula for the mean weakening with time of the whole sample.

Dimer motion on a periodic substrate: spontaneous symmetry breaking and absolute negative mobility.

PubMed

Speer, David; Eichhorn, Ralf; Evstigneev, Mykhaylo; Reimann, Peter

2012-06-01

We consider two coupled particles moving along a periodic substrate potential with negligible inertia effects (overdamped limit). Even when the particles are identical and the substrate spatially symmetric, a sinusoidal external driving of appropriate amplitude and frequency may lead to spontaneous symmetry breaking in the form of a permanent directed motion of the dimer. Thermal noise restores ergodicity and thus zero net velocity, but entails arbitrarily fast diffusion of the dimer for sufficiently weak noise. Moreover, upon application of a static bias force, the dimer exhibits a motion opposite to that force (absolute negative mobility). The key requirement for all these effects is a nonconvex interaction potential of the two particles.

Deciphering the Landauer-Büttiker Transmission Function from Single Molecule Break Junction Experiments

NASA Astrophysics Data System (ADS)

Reuter, Matthew; Tschudi, Stephen

When investigating the electrical response properties of molecules, experiments often measure conductance whereas computation predicts transmission probabilities. Although the Landauer-Büttiker theory relates the two in the limit of coherent scattering through the molecule, a direct comparison between experiment and computation can still be difficult. Experimental data (specifically that from break junctions) is statistical and computational results are deterministic. Many studies compare the most probable experimental conductance with computation, but such an analysis discards almost all of the experimental statistics. In this work we develop tools to decipher the Landauer-Büttiker transmission function directly from experimental statistics and then apply them to enable a fairer comparison between experimental and computational results.

Introduction to the virtual special issue on super-resolution imaging techniques

NASA Astrophysics Data System (ADS)

Cao, Liangcai; Liu, Zhengjun

2017-12-01

Until quite recently, the resolution of optical imaging instruments, including telescopes, cameras and microscopes, was considered to be limited by the diffraction of light and by image sensors. In the past few years, many exciting super-resolution approaches have emerged that demonstrate intriguing ways to bypass the classical limit in optics and detectors. More and more research groups are engaged in the study of advanced super-resolution schemes, devices, algorithms, systems, and applications [1-6]. Super-resolution techniques involve new methods in science and engineering of optics [7,8], measurements [9,10], chemistry [11,12] and information [13,14]. Promising applications, particularly in biomedical research and semiconductor industry, have been successfully demonstrated.

Breaking the Equation

ERIC Educational Resources Information Center

Stylianides, Andreas J.

2009-01-01

A proof's potential to promote understanding and conviction is one of the main reasons for which proof is so important for students' learning of mathematics. Unless students realise the limitations of empirical arguments as methods for validating mathematical generalisations, they are unlikely to appreciate the importance of proof in mathematics.…

Phosphorus losses from drainage systems: breaking the surface tile riser connection

USDA-ARS?s Scientific Manuscript database

In freshwater ecosystems, phosphorus is generally the nutrient most limiting algal growth. Agricultural drainage systems in the upper Midwestern US are generally designed to drain water as quickly as possible, in order to ensure trafficability and minimize crop damage due to flooding. An unintended ...

Spatiotemporal Imaging of Magnetization Dynamics at the Nanoscale: Breaking the Diffraction Limit

DTIC Science & Technology

2016-03-09

modulations frequency. In the future under our new AFOSR contract, we plan to fabricate a new generation of devices with appropriate impedance match to a...quantitatively extract relevant thermal parameters from our experiment including the temperature change and the magnto- thermoelectric coefficient. Response

Breaking new ground in mapping human settlements from space - The Global Urban Footprint

NASA Astrophysics Data System (ADS)

Esch, Thomas; Heldens, Wieke; Hirner, Andreas; Keil, Manfred; Marconcini, Mattia; Roth, Achim; Zeidler, Julian; Dech, Stefan; Strano, Emanuele

2017-12-01

Today, approximately 7.2 billion people inhabit the Earth and by 2050 this number will have risen to around nine billion, of which about 70% will be living in cities. The population growth and the related global urbanization pose one of the major challenges to a sustainable future. Hence, it is essential to understand drivers, dynamics, and impacts of the human settlements development. A key component in this context is the availability of an up-to-date and spatially consistent map of the location and distribution of human settlements. It is here that the Global Urban Footprint (GUF) raster map can make a valuable contribution. The new global GUF binary settlement mask shows a so far unprecedented spatial resolution of 0.4″ (∼ 12m) that provides - for the first time - a complete picture of the entirety of urban and rural settlements. The GUF has been derived by means of a fully automated processing framework - the Urban Footprint Processor (UFP) - that was used to analyze a global coverage of more than 180,000 TanDEM-X and TerraSAR-X radar images with 3 m ground resolution collected in 2011-2012. The UFP consists of five main technical modules for data management, feature extraction, unsupervised classification, mosaicking and post-editing. Various quality assessment studies to determine the absolute GUF accuracy based on ground truth data on the one hand and the relative accuracies compared to established settlements maps on the other hand, clearly indicate the added value of the new global GUF layer, in particular with respect to the representation of rural settlement patterns. The Kappa coefficient of agreement compared to absolute ground truth data, for instance, shows GUF accuracies which are frequently twice as high as those of established low resolution maps. Generally, the GUF layer achieves an overall absolute accuracy of about 85%, with observed minima around 65% and maxima around 98%. The GUF will be provided open and free for any scientific use in the full resolution and for any non-profit (but also non-scientific) use in a generalized version of 2.8″ (∼ 84m). Therewith, the new GUF layer can be expected to break new ground with respect to the analysis of global urbanization and peri-urbanization patterns, population estimation, vulnerability assessment, or the modeling of diseases and phenomena of global change in general.

Smc5/6-Mms21 Prevents and Eliminates Inappropriate Recombination Intermediates in Meiosis

PubMed Central

Xaver, Martin; Huang, Lingzhi; Chen, Doris; Klein, Franz

2013-01-01

Repairing broken chromosomes via joint molecule (JM) intermediates is hazardous and therefore strictly controlled in most organisms. Also in budding yeast meiosis, where production of enough crossovers via JMs is imperative, only a subset of DNA breaks are repaired via JMs, closely regulated by the ZMM pathway. The other breaks are repaired to non-crossovers, avoiding JM formation, through pathways that require the BLM/Sgs1 helicase. “Rogue” JMs that escape the ZMM pathway and BLM/Sgs1 are eliminated before metaphase by resolvases like Mus81-Mms4 to prevent chromosome nondisjunction. Here, we report the requirement of Smc5/6-Mms21 for antagonizing rogue JMs via two mechanisms; destabilizing early intermediates and resolving JMs. Elimination of the Mms21 SUMO E3-ligase domain leads to transient JM accumulation, depending on Mus81-Mms4 for resolution. Absence of Smc6 leads to persistent rogue JMs accumulation, preventing chromatin separation. We propose that the Smc5/6-Mms21 complex antagonizes toxic JMs by coordinating helicases and resolvases at D-Loops and HJs, respectively. PMID:24385936

Forming Disc Galaxies In Major Mergers: Radial Density Profiles And Angular Momentum

NASA Astrophysics Data System (ADS)

Peschken, Nicolas; Athanassoula, E.; Rodionov, S. A.; Lambert, J. C.

2017-06-01

In Athanassoula et al. (2016), we used high resolution N-body hydrodynamical simulations to model the major merger between two disc galaxies with a hot gaseous halo each, and showed that the remnant is a spiral galaxy. The two discs are destroyed by the collision, but after the merger, accretion from the surrounding gaseous halo allows the building of a new disc in the remnant galaxy. In Peschken et al. (2017), we used these simulations to study the radial surface density profiles of the remnant galaxies with downbending profiles (type II), i.e. composed of an inner and an outer exponential disc separated by a break. We analyzed the effect of angular momentum on these profiles, and found that the inner and outer disc scalelengths, as well as the break radius, all increase linearly with the total angular momentum of the initial merging system. Following the angular momentum redistribution in our simulations, we find that the disc angular momentum is acquired via accretion from the gaseous halo. Furthermore, high angular momentum systems give more angular momentum to their discs, which affects directly their radial density profile.

NIMROD resistive magnetohydrodynamic simulations of spheromak physics

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

Hooper, E. B.; Cohen, B. I.; McLean, H. S.

The physics of spheromak plasmas is addressed by time-dependent, three-dimensional, resistive magnetohydrodynamic simulations with the NIMROD code [C. R. Sovinec et al., J. Comput. Phys. 195, 355 (2004)]. Included in some detail are the formation of a spheromak driven electrostatically by a coaxial plasma gun with a flux-conserver geometry and power systems that accurately model the sustained spheromak physics experiment [R. D. Wood et al., Nucl. Fusion 45, 1582 (2005)]. The controlled decay of the spheromak plasma over several milliseconds is also modeled as the programmable current and voltage relax, resulting in simulations of entire experimental pulses. Reconnection phenomena andmore » the effects of current profile evolution on the growth of symmetry-breaking toroidal modes are diagnosed; these in turn affect the quality of magnetic surfaces and the energy confinement. The sensitivity of the simulation results addresses variations in both physical and numerical parameters, including spatial resolution. There are significant points of agreement between the simulations and the observed experimental behavior, e.g., in the evolution of the magnetics and the sensitivity of the energy confinement to the presence of symmetry-breaking magnetic fluctuations.« less

NIMROD Resistive Magnetohydrodynamic Simulations of Spheromak Physics

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

Hooper, E B; Cohen, B I; McLean, H S

The physics of spheromak plasmas is addressed by time-dependent, three-dimensional, resistive magneto-hydrodynamic simulations with the NIMROD code. Included in some detail are the formation of a spheromak driven electrostatically by a coaxial plasma gun with a flux-conserver geometry and power systems that accurately model the Sustained Spheromak Physics Experiment (SSPX) (R. D. Wood, et al., Nucl. Fusion 45, 1582 (2005)). The controlled decay of the spheromak plasma over several milliseconds is also modeled as the programmable current and voltage relax, resulting in simulations of entire experimental pulses. Reconnection phenomena and the effects of current profile evolution on the growth ofmore » symmetry-breaking toroidal modes are diagnosed; these in turn affect the quality of magnetic surfaces and the energy confinement. The sensitivity of the simulation results address variations in both physical and numerical parameters, including spatial resolution. There are significant points of agreement between the simulations and the observed experimental behavior, e.g., in the evolution of the magnetics and the sensitivity of the energy confinement to the presence of symmetry-breaking magnetic fluctuations.« less

Resolution Quality and Atom Positions in Sub-Angstrom Electron Microscopy

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

O'Keefe, Michael A.; Allard, Lawrence F.; Blom, Douglas A.

2005-02-15

Ability to determine whether an image peak represents one single atom or several depends on resolution of the HR-(S)TEM. Rayleigh's resolution criterion, an accepted standard in optics, was derived as a means for judging when two image intensity peaks from two sources of light (stars) are distinguishable from a single source. Atom spacings closer than the Rayleigh limit have been resolved in HR-TEM, suggesting that it may be useful to consider other limits, such as the Sparrow resolution criterion. From the viewpoint of the materials scientist, it is important to be able to use the image to determine whether anmore » image feature represents one or more atoms (resolution), and where the atoms (or atom columns) are positioned relative to one another (resolution quality). When atoms and the corresponding image peaks are separated by more than the Rayleigh limit of the HR-(S)TEM, it is possible to adjust imaging parameters so that relative peak positions in the image correspond to relative atom positions in the specimen. When atoms are closer than the Rayleigh limit, we must find the relationship of the peak position to the atom position by peak fitting or, if we have a suitable model, by image simulation. Our Rayleigh-Sparrow parameter QRS reveals the ''resolution quality'' of a microscope image. QRS values greater than 1 indicate a clearly resolved twin peak, while values between 1 and 0 mean a lower-quality resolution and an image with peaks displaced from the relative atom positions. The depth of the twin-peak minimum can be used to determine the value of QRS and the true separation of the atom peaks that sum to produce the twin peak in the image. The Rayleigh-Sparrow parameter can be used to refine relative atom positions in defect images where atoms are closer than the Rayleigh limit of the HR-(S)TEM, reducing the necessity for full image simulations from large defect models.« less

What is the spatial sampling of MISR?

Atmospheric Science Data Center

2014-12-08

... spatial resolution of the sensors without exceeding the data transfer quotas, MISR can be operated in two different data acquisition modes: ... data at the full resolution, but only for limited periods of time and therefore for limited regions, typically about 300 km in length (along ...

Quantity not quality: The relationship between fluid intelligence and working memory capacity

PubMed Central

Fukuda, Keisuke; Vogel, Edward; Mayr, Ulrich; Awh, Edward

2010-01-01

A key motivation for understanding capacity in working memory (WM) is its relationship with fluid intelligence. Recent evidence has suggested a 2-factor model that distinguishes between the number of representations that can be maintained in WM and the resolution of those representations. To determine how these factors relate to fluid intelligence, we conducted an exploratory factor analysis on multiple number-limited and resolution-limited measures of WM ability. The results strongly supported the 2-factor model, with fully orthogonal factors accounting for performance in the number-limited and resolution-limited conditions. Furthermore, the reliable relationship between WM capacity and fluid intelligence was exclusively supported by the number factor (r = .66), while the resolution factor made no reliable contribution (r = −.05). Thus, the relationship between WM capacity and standard measures of fluid intelligence is mediated by the number of representations that can be simultaneously maintained in WM rather than by the precision of those representations. PMID:21037165

Australia's Unprecedented Future Temperature Extremes Under Paris Limits to Warming

NASA Astrophysics Data System (ADS)

Lewis, Sophie C.; King, Andrew D.; Mitchell, Daniel M.

2017-10-01

Record-breaking temperatures can detrimentally impact ecosystems, infrastructure, and human health. Previous studies show that climate change has influenced some observed extremes, which are expected to become more frequent under enhanced future warming. Understanding the magnitude, as a well as frequency, of such future extremes is critical for limiting detrimental impacts. We focus on temperature changes in Australian regions, including over a major coral reef-building area, and assess the potential magnitude of future extreme temperatures under Paris Agreement global warming targets (1.5°C and 2°C). Under these limits to global mean warming, we determine a set of projected high-magnitude unprecedented Australian temperature extremes. These include extremes unexpected based on observational temperatures, including current record-breaking events. For example, while the difference in global-average warming during the hottest Australian summer and the 2°C Paris target is 1.1°C, extremes of 2.4°C above the observed summer record are simulated. This example represents a more than doubling of the magnitude of extremes, compared with global mean change, and such temperatures are unexpected based on the observed record alone. Projected extremes do not necessarily scale linearly with mean global warming, and this effect demonstrates the significant potential benefits of limiting warming to 1.5°C, compared to 2°C or warmer.

Local-duality QCD sum rules for strong isospin breaking in the decay constants of heavy-light mesons.

PubMed

Lucha, Wolfgang; Melikhov, Dmitri; Simula, Silvano

2018-01-01

We discuss the leptonic decay constants of heavy-light mesons by means of Borel QCD sum rules in the local-duality (LD) limit of infinitely large Borel mass parameter. In this limit, for an appropriate choice of the invariant structures in the QCD correlation functions, all vacuum-condensate contributions vanish and all nonperturbative effects are contained in only one quantity, the effective threshold. We study properties of the LD effective thresholds in the limits of large heavy-quark mass [Formula: see text] and small light-quark mass [Formula: see text]. In the heavy-quark limit, we clarify the role played by the radiative corrections in the effective threshold for reproducing the pQCD expansion of the decay constants of pseudoscalar and vector mesons. We show that the dependence of the meson decay constants on [Formula: see text] arises predominantly (at the level of 70-80%) from the calculable [Formula: see text]-dependence of the perturbative spectral densities. Making use of the lattice QCD results for the decay constants of nonstrange and strange pseudoscalar and vector heavy mesons, we obtain solid predictions for the decay constants of heavy-light mesons as functions of [Formula: see text] in the range from a few to 100 MeV and evaluate the corresponding strong isospin-breaking effects: [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text].

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

Manolopoulou, Marika; Guo, Qing; Malito, Enrico

Insulin is a hormone vital for glucose homeostasis, and insulin-degrading enzyme (IDE) plays a key role in its clearance. IDE exhibits a remarkable specificity to degrade insulin without breaking the disulfide bonds that hold the insulin A and B chains together. Using Fourier transform ion cyclotron resonance (FTICR) mass spectrometry to obtain high mass accuracy, and electron capture dissociation (ECD) to selectively break the disulfide bonds in gas phase fragmentation, we determined the cleavage sites and composition of human insulin fragments generated by human IDE. Our time-dependent analysis of IDE-digested insulin fragments reveals that IDE is highly processive in itsmore » initial cleavage at the middle of both the insulin A and B chains. This ensures that IDE effectively splits insulin into inactive N- and C-terminal halves without breaking the disulfide bonds. To understand the molecular basis of the recognition and unfolding of insulin by IDE, we determined a 2.6-A resolution insulin-bound IDE structure. Our structure reveals that IDE forms an enclosed catalytic chamber that completely engulfs and intimately interacts with a partially unfolded insulin molecule. This structure also highlights how the unique size, shape, charge distribution, and exosite of the IDE catalytic chamber contribute to its high affinity ( approximately 100 nm) for insulin. In addition, this structure shows how IDE utilizes the interaction of its exosite with the N terminus of the insulin A chain as well as other properties of the catalytic chamber to guide the unfolding of insulin and allowing for the processive cleavages.« less

Predictions of the spontaneous symmetry-breaking theory for visual code completeness and spatial scaling in single-cell learning rules.

PubMed

Webber, C J

2001-05-01

This article shows analytically that single-cell learning rules that give rise to oriented and localized receptive fields, when their synaptic weights are randomly and independently initialized according to a plausible assumption of zero prior information, will generate visual codes that are invariant under two-dimensional translations, rotations, and scale magnifications, provided that the statistics of their training images are sufficiently invariant under these transformations. Such codes span different image locations, orientations, and size scales with equal economy. Thus, single-cell rules could account for the spatial scaling property of the cortical simple-cell code. This prediction is tested computationally by training with natural scenes; it is demonstrated that a single-cell learning rule can give rise to simple-cell receptive fields spanning the full range of orientations, image locations, and spatial frequencies (except at the extreme high and low frequencies at which the scale invariance of the statistics of digitally sampled images must ultimately break down, because of the image boundary and the finite pixel resolution). Thus, no constraint on completeness, or any other coupling between cells, is necessary to induce the visual code to span wide ranges of locations, orientations, and size scales. This prediction is made using the theory of spontaneous symmetry breaking, which we have previously shown can also explain the data-driven self-organization of a wide variety of transformation invariances in neurons' responses, such as the translation invariance of complex cell response.

Mechanism of reentry induction by a 9-V battery in rabbit ventricles

PubMed Central

Burton, Rebecca A. B.; Kalla, Manish; Nanthakumar, Kumaraswamy; Plank, Gernot; Bub, Gil; Vigmond, Edward J.

2014-01-01

Although the application of a 9-V battery to the epicardial surface is a simple method of ventricular fibrillation induction, the fundamental mechanisms underlying this process remain unstudied. We used a combined experimental and modelling approach to understand how the interaction of direct current (DC) from a battery may induce reentrant activity within rabbit ventricles and its dependence on battery application timing and duration. A rabbit ventricular computational model was used to simulate 9-V battery stimulation for different durations at varying onset times during sinus rhythm. Corresponding high-resolution optical mapping measurements were conducted on rabbit hearts with DC stimuli applied via a relay system. DC application to diastolic tissue induced anodal and cathodal make excitations in both simulations and experiments. Subsequently, similar static epicardial virtual electrode patterns were formed that interacted with sinus beats but did not induce reentry. Upon battery release during diastole, break excitations caused single ectopics, similar to application, before sinus rhythm resumed. Reentry induction was possible for short battery applications when break excitations were slowed and forced to take convoluted pathways upon interaction with refractory tissue from prior make excitations or sinus beats. Short-lived reentrant activity could be induced for battery release shortly after a sinus beat for longer battery applications. In conclusion, the application of a 9-V battery to the epicardial surface induces reentry through a complex interaction of break excitations after battery release with prior induced make excitations or sinus beats. PMID:24464758

Mechanism of reentry induction by a 9-V battery in rabbit ventricles.

PubMed

Bishop, Martin J; Burton, Rebecca A B; Kalla, Manish; Nanthakumar, Kumaraswamy; Plank, Gernot; Bub, Gil; Vigmond, Edward J

2014-04-01

Although the application of a 9-V battery to the epicardial surface is a simple method of ventricular fibrillation induction, the fundamental mechanisms underlying this process remain unstudied. We used a combined experimental and modelling approach to understand how the interaction of direct current (DC) from a battery may induce reentrant activity within rabbit ventricles and its dependence on battery application timing and duration. A rabbit ventricular computational model was used to simulate 9-V battery stimulation for different durations at varying onset times during sinus rhythm. Corresponding high-resolution optical mapping measurements were conducted on rabbit hearts with DC stimuli applied via a relay system. DC application to diastolic tissue induced anodal and cathodal make excitations in both simulations and experiments. Subsequently, similar static epicardial virtual electrode patterns were formed that interacted with sinus beats but did not induce reentry. Upon battery release during diastole, break excitations caused single ectopics, similar to application, before sinus rhythm resumed. Reentry induction was possible for short battery applications when break excitations were slowed and forced to take convoluted pathways upon interaction with refractory tissue from prior make excitations or sinus beats. Short-lived reentrant activity could be induced for battery release shortly after a sinus beat for longer battery applications. In conclusion, the application of a 9-V battery to the epicardial surface induces reentry through a complex interaction of break excitations after battery release with prior induced make excitations or sinus beats.

Single nucleotide-level mapping of DNA double-strand breaks in human HEK293T cells.

PubMed

Pope, Bernard J; Mahmood, Khalid; Jung, Chol-Hee; Georgeson, Peter; Park, Daniel J

2017-03-01

Constitutional biological processes involve the generation of DNA double-strand breaks (DSBs). The production of such breaks and their subsequent resolution are also highly relevant to neurodegenerative diseases and cancer, in which extensive DNA fragmentation has been described Stephens et al. (2011), Blondet et al. (2001). Tchurikov et al. Tchurikov et al. (2011, 2013) have reported previously that frequent sites of DSBs occur in chromosomal domains involved in the co-ordinated expression of genes. This group report that hot spots of DSBs in human HEK293T cells often coincide with H3K4me3 marks, associated with active transcription Kravatsky et al. (2015) and that frequent sites of DNA double-strand breakage are likely to be relevant to cancer genomics Tchurikov et al. (2013, 2016) . Recently, they applied a RAFT (rapid amplification of forum termini) protocol that selects for blunt-ended DSB sites and mapped these to the human genome within defined co-ordinate 'windows'. In this paper, we re-analyse public RAFT data to derive sites of DSBs at the single-nucleotide level across the built genome for human HEK293T cells (https://figshare.com/s/35220b2b79eaaaf64ed8). This refined mapping, combined with accessory ENCODE data tracks and ribosomal DNA-related sequence annotations, will likely be of value for the design of clinically relevant targeted assays such as those for cancer susceptibility, diagnosis, treatment-matching and prognostication.

Study of high-power GaAs-based laser diodes operation and failure by cross-sectional electrostatic force microscopy

NASA Astrophysics Data System (ADS)

Ankudinov, A.; Titkov, A. N.; Evtikhiev, Vadim P.; Kotelnikov, Eugeny Y.; Bazhenov, N.; Zegrya, Georgy G.; Huhtinen, H.; Laiho, R.

2003-06-01

One of the important factors that restricts the power limit of semiconductor lasers is a catastrophic optical mirror damage. This process is significantly suppressed through decreasing the optical power density due to its redistribution over the broad transverse waveguide (BW). Recently it was shown that record-breaking values of the quasicontinuous and continuous-wave (QWC and CW) output power for 100-μm-wide-aperture devices can be achieved by incorporating a broad transverse waveguide into 0.97 μm emitting Al-free InGaAs(P)/InGaP/GaAs and Al-containing InGaAs/AlGaAs/GaAs separate confinement heterostructure quantum-well lasers (SCH-QWL). Another important factor limiting the CW output power is the Joule overheating of a laser diode due to an extra serial resistance. Traditionally, a decrease in the resistance is achieved by development of the contacts, whereas a voltage distribution across the device structure is not analyzed properly. At high operating currents the applied voltage can drop not only across the n-p-junction, but also at certain additional regions of the laser structure depending on a particular design of the device. Electrostatic force microscopy (EFM) provides a very promising method to study the voltage distribution across an operating device with a nanometer space resolution. An application of EFM for diagnostics of III-V laser diodes without and under applied biases have been recently demonstrated. However, the most interesting range of the biases, the lazing regime, has not been studied yet.

Development of an amorphous selenium based photoconductor and its application in a high-sensitivity photodetector (Conference Presentation)

NASA Astrophysics Data System (ADS)

Masuzawa, Tomoaki; Ebisudani, Taishi; Ochiai, Jun; Saito, Ichitaro; Yamada, Takatoshi; Chua, Daniel H. C.; Mimura, Hidenori; Okano, Ken

2016-09-01

Although present imaging devices are mostly silicon-based devices such as CMOS and CCD, these devices are reaching their sensitivity limit due to the band gap of silicon. Amorphous selenium (a-Se) is a promising candidate for high- sensitivity photo imaging devices, because of its low thermal noise, high spatial resolution, as well as adaptability to wide-area deposition. In addition, internal signal amplification is reported on a-Se based photodetectors, which enables a photodetector having effective quantum efficiency over 100 % against visible light. Since a-Se has sensitivity to UV and soft X-rays, the reported internal signal amplification should be applicable to UV and X-ray detection. However, application of the internal signal amplification required high voltage, which caused unexpected breakdown at the contact or thin-film transistor-based signal read-out. For this reason, vacuum devices having electron-beam read-out is proposed. The advantages of vacuum-type devices are vacuum insulation and its extremely low dark current. In this study, we present recent progresses in developing a-Se based photoconductive films and photodetector using nitrogen-doped diamond electron beam source as signal read-out. A novel electrochemical method is used to dope impurities into a-Se, turning the material from weak p-type to n-type. A p-n junction is formed within a-Se photoconductive film, which has increased the sensitivity of a-Se based photodetector. Our result suggests a possibility of high sensitivity photodetector that can potentially break the limit of silicon-based devices.

Lensfree on-chip microscopy over a wide field-of-view using pixel super-resolution

PubMed Central

Bishara, Waheb; Su, Ting-Wei; Coskun, Ahmet F.; Ozcan, Aydogan

2010-01-01

We demonstrate lensfree holographic microscopy on a chip to achieve ~0.6 µm spatial resolution corresponding to a numerical aperture of ~0.5 over a large field-of-view of ~24 mm2. By using partially coherent illumination from a large aperture (~50 µm), we acquire lower resolution lensfree in-line holograms of the objects with unit fringe magnification. For each lensfree hologram, the pixel size at the sensor chip limits the spatial resolution of the reconstructed image. To circumvent this limitation, we implement a sub-pixel shifting based super-resolution algorithm to effectively recover much higher resolution digital holograms of the objects, permitting sub-micron spatial resolution to be achieved across the entire sensor chip active area, which is also equivalent to the imaging field-of-view (24 mm2) due to unit magnification. We demonstrate the success of this pixel super-resolution approach by imaging patterned transparent substrates, blood smear samples, as well as Caenoharbditis Elegans. PMID:20588977

Global analysis of double-strand break processing reveals in vivo properties of the helicase-nuclease complex AddAB

PubMed Central

Badrinarayanan, Anjana; Cisse, Ibrahim I.

2017-01-01

In bacteria, double-strand break (DSB) repair via homologous recombination is thought to be initiated through the bi-directional degradation and resection of DNA ends by a helicase-nuclease complex such as AddAB. The activity of AddAB has been well-studied in vitro, with translocation speeds between 400–2000 bp/s on linear DNA suggesting that a large section of DNA around a break site is processed for repair. However, the translocation rate and activity of AddAB in vivo is not known, and how AddAB is regulated to prevent excessive DNA degradation around a break site is unclear. To examine the functions and mechanistic regulation of AddAB inside bacterial cells, we developed a next-generation sequencing-based approach to assay DNA processing after a site-specific DSB was introduced on the chromosome of Caulobacter crescentus. Using this assay we determined the in vivo rates of DSB processing by AddAB and found that putative chi sites attenuate processing in a RecA-dependent manner. This RecA-mediated regulation of AddAB prevents the excessive loss of DNA around a break site, limiting the effects of DSB processing on transcription. In sum, our results, taken together with prior studies, support a mechanism for regulating AddAB that couples two key events of DSB repair–the attenuation of DNA-end processing and the initiation of homology search by RecA–thereby helping to ensure that genomic integrity is maintained during DSB repair. PMID:28489851

The Break Up: Evaluation of an Anti-Smoking Educational Campaign for Lesbians, Gays, and Bisexuals in Los Angeles County.

PubMed

Plant, Aaron; Montoya, Jorge A; Tyree, Rachel; Aragon, Linda; Weber, Mark; Le Veque, Matthew; Anderson, Christopher M; Soler, Robin E; Kent, Charlotte

2017-01-01

Lesbian, gay, and bisexual (LGB) adults in the United States have a higher prevalence of smoking than their heterosexual counterparts. In 2013, the Los Angeles County Department of Public Health launched a social marketing and outreach campaign called Break Up to reduce the prevalence of smoking in LGB communities. Break Up was evaluated using cross-sectional, street-intercept surveys before and near the end of campaign. Surveys measured demographics, campaign awareness, and self-reported smoking-related outcomes. Bivariate statistics and logistic regression models were used to identify whether campaign awareness was associated with smoking-related outcomes. Calls by LGB persons to a smokers' helpline were also measured. Among those interviewed at endline, 32.7% reported Break Up awareness. Awareness was associated with thinking of quitting smoking and ever taking steps to quit but not with smoking cessation (defined as not smoking in the past 30 days among those who had smoked in the past 6 months). There was a 0.7% increase in the percentage of weekly calls by LGB persons to the helpline in the year after the campaign. Break Up reached about a third of its intended audience. The campaign was associated with smoking cessation precursors and may have led to an increase in helpline utilization, but there is no evidence it affected quit attempts. This study adds to the limited literature on tobacco programs for LGB persons and, as far as we know, is one of the first to evaluate tobacco-free social marketing in this important yet understudied population.

Ultrasonication-assisted synthesis of high aspect ratio gold nanowires on a graphene template and investigation of their growth mechanism.

PubMed

Xin, Wenbo; De Rosa, Igor M; Cao, Yang; Yin, Xunqian; Yu, Hang; Ye, Peiyi; Carlson, Larry; Yang, Jenn-Ming

2018-04-19

We report a facile synthesis of Au nanowires (AuNWs) with a high aspect ratio (l/D) of up to 5000 on a plasma activated graphene template with ultrasound assistance. We demonstrate that the ultrasonication induced symmetry breaking of Au clusters facilitates the growth of AuNWs from the embryonic stages. Furthermore, the growth mechanism of AuNWs is systematically investigated using high resolution electron transmission microscopy (HRTEM), which reveals the unique role of the defective graphene template in directing the growth of AuNWs.

Quantum information cannot be completely hidden in correlations: implications for the black-hole information paradox.

PubMed

Braunstein, Samuel L; Pati, Arun K

2007-02-23

Can quantum-information theory shed light on black-hole evaporation? By entangling the in-fallen matter with an external system we show that the black-hole information paradox becomes more severe, even for cosmologically sized black holes. We rule out the possibility that the information about the in-fallen matter might hide in correlations between the Hawking radiation and the internal states of the black hole. As a consequence, either unitarity or Hawking's semiclassical predictions must break down. Any resolution of the black-hole information crisis must elucidate one of these possibilities.

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

Diaz Cruz, J. Lorenzo

We suggest that dark matter can be identified with a stable composite fermion X{sup 0}, that arises within the holographic AdS/CFT models, where the Higgs boson emerges as a composite pseudo-goldstone boson. The predicted properties of X{sup 0} satisfies the cosmological bounds, with m{sub X{sup 0}}{approx}4{pi}f{approx_equal}O(TeV). Thus, through a deeper understanding of the mechanism of electroweak symmetry breaking, a resolution of the Dark Matter enigma is found. Furthermore, by proposing a discrete structure of the Higgs vacuum, one can get a distinct approach to the cosmological constant problem.

Observation of the ankle and evidence for a high-energy break in the cosmic ray spectrum

NASA Astrophysics Data System (ADS)

Abbasi, R.; Abuzayyad, T.; Amman, J.; Archbold, G.; Atkins, R.; Bellido, J.; Belov, K.; Belz, J.; Benzvi, S.; Bergman, D.

2005-07-01

We have measured the cosmic ray spectrum at energies above $10^{17}$ eV using the two air fluorescence detectors of the High Resolution Fly's Eye experiment operating in monocular mode. We describe the detector, PMT and atmospheric calibrations, and the analysis techniques for the two detectors. We fit the spectrum to models describing galactic and extragalactic sources. Our measured spectrum gives an observation of a feature known as the ``ankle'' near $3\\times 10^{18}$ eV, and strong evidence for a suppression near $6\\times 10^{19}$ eV.

Leadership Accountability Models: Issues of Policy and Practice.

ERIC Educational Resources Information Center

Wallace, Stephen O.; Sweatt, Owen; Acker-Hocevar, Michele

This paper explores two questions: "What philosophical views of educational leadership will adequately allow us to meet the demands of a rapidly changing world?" and "How should such leadership be assessed?" The article asserts that evaluation of educational leadership needs to break away from the limitations of restrictive models to become…

Breaking the Cycle: Future Faculty Begin Teaching with Learner-Centered Strategies after Professional Development

ERIC Educational Resources Information Center

Ebert-May, Diane; Derting, Terry L.; Henkel, Timothy P.; Maher, Jessica Middlemis; Momsen, Jennifer L.; Arnold, Bryan; Passmore, Heather A.

2015-01-01

The availability of reliable evidence for teaching practices after professional development is limited across science, technology, engineering, and mathematics disciplines, making the identification of professional development "best practices" and effective models for change difficult. We aimed to determine the extent to which…

5 CFR 530.204 - Payment of excess amounts.

Code of Federal Regulations, 2010 CFR

2010-01-01

... agency must pay the entire excess amount following a 30-day break in service. If the individual is... Section 530.204 Administrative Personnel OFFICE OF PERSONNEL MANAGEMENT CIVIL SERVICE REGULATIONS PAY RATES AND SYSTEMS (GENERAL) Aggregate Limitation on Pay § 530.204 Payment of excess amounts. (a) An...

On the numerical treatment of Coulomb forces in scattering problems

NASA Astrophysics Data System (ADS)

Randazzo, J. M.; Ancarani, L. U.; Colavecchia, F. D.; Gasaneo, G.; Frapiccini, A. L.

2012-11-01

We investigate the limiting procedures to obtain Coulomb interactions from short-range potentials. The application of standard techniques used for the two-body case (exponential and sharp cutoff) to the three-body break-up problem is illustrated numerically by considering the Temkin-Poet (TP) model of e-H processes.

Oral Anatomy Laboratory Examinations in a Physical Therapy Program

ERIC Educational Resources Information Center

Fabrizio, Philip A.

2013-01-01

The process of creating and administering traditional tagged anatomy laboratory examinations is time consuming for instructors and limits laboratory access for students. Depending on class size and the number of class, sections, creating, administering, and breaking down a tagged laboratory examination may involve one to two eight-hour days.…

Hazard report. Internal wire breakage in reusable electrosurgical active electrode cables may cause sparking and surgical fires.

PubMed

2009-07-01

Breaks in the internal wires of reusable electrosurgical active electrode cables can increase the risk of injuries and surgical fires. Careful visual and manual inspection during reprocessing and immediately before use, coupled with periodic replacement, can help limit the risk.

Breaking the Silence: Toward Improving LGBTQ Representation in Composition Readers

ERIC Educational Resources Information Center

Hudson, John

2014-01-01

Lesbian-Gay-Bisexual-Transgender-Queer (LGBTQ) representation in composition readers remains limited and is frequently nonexistent. In addition, the LGBTQ-related materials that do find their way into composition readers are often problematic. In this essay I explain why WPAs and composition teachers should be concerned about LGBTQ representation…

The School-to-Prison Pipeline: From School Punishment to Rehabilitative Inclusion

ERIC Educational Resources Information Center

Mallett, Christopher A.

2016-01-01

The zero tolerance policy movement across most of this country's school districts significantly limited school personnel's disciplinary alternatives for students who break rules on campus. This has resulted in millions of primary and secondary age students who have experienced suspension, arrests, and for some, expulsion. Within the student…

Investigating the role of extensin proteins in poplar biomass recalcitrance

USDA-ARS?s Scientific Manuscript database

The biological conversion of cellulosic biomass to biofuel is hindered by cell wall recalcitrance, which can limit the ability of cellulases to access and break down cellulose. The purpose of this study was to investigate whether hydroxyproline-rich cell wall proteins (extensins) are present in popl...

ArtBreak Group Counseling for Children: Framework, Practice Points, and Results

ERIC Educational Resources Information Center

Ziff, Katherine; Ivers, Nathaniel N.; Shaw, Edward G.

2016-01-01

Child social/emotional development and mitigation of child stress are receiving continued emphasis in the literature. While choice-based group art studios have a long association with mental health, documentation on their potential for supporting children is limited. This article describes an elementary school counseling intervention designed to…

Colonic Fermentation: A Neglected Topic in Human Physiology Education

ERIC Educational Resources Information Center

Valeur, Jorgen; Berstad, Arnold

2010-01-01

Human physiology textbooks tend to limit their discussion of colonic functions to those of absorbing water and electrolytes and storing waste material. However, the colon is a highly active metabolic organ, containing an exceedingly complex society of microbes. By means of fermentation, gastrointestinal microbes break down nutrients that cannot be…

Chemical Safety Alert: Emergency Isolation for Hazardous Material Fluid Transfer Systems - Application and Limitations of Excess Flow Valves

EPA Pesticide Factsheets

While excess flow valves (EFV) are in extensive service and have prevented numerous pipe or hose breaks from becoming much more serious incidents, experience shows that in some cases the EFV did not perform as intended, usually because of misapplication.

In the Names of Chinese Women.

ERIC Educational Resources Information Center

Lee, Wen Shu

1998-01-01

Contributes to both feminist scholarship and Chinese Studies by coming to grips with the deep, culturally embedded, and politically significant meaning of the names given to Chinese women. Uses the analysis of two names to advance theory that will link and enrich rhetorical, feminist, and intercultural studies and break through the limits of…

ExpertEyes: open-source, high-definition eyetracking.

PubMed

Parada, Francisco J; Wyatte, Dean; Yu, Chen; Akavipat, Ruj; Emerick, Brandi; Busey, Thomas

2015-03-01

ExpertEyes is a low-cost, open-source package of hardware and software that is designed to provide portable high-definition eyetracking. The project involves several technological innovations, including portability, high-definition video recording, and multiplatform software support. It was designed for challenging recording environments, and all processing is done offline to allow for optimization of parameter estimation. The pupil and corneal reflection are estimated using a novel forward eye model that simultaneously fits both the pupil and the corneal reflection with full ellipses, addressing a common situation in which the corneal reflection sits at the edge of the pupil and therefore breaks the contour of the ellipse. The accuracy and precision of the system are comparable to or better than what is available in commercial eyetracking systems, with a typical accuracy of less than 0.4° and best accuracy below 0.3°, and with a typical precision (SD method) around 0.3° and best precision below 0.2°. Part of the success of the system comes from a high-resolution eye image. The high image quality results from uncasing common digital camcorders and recording directly to SD cards, which avoids the limitations of the analog NTSC format. The software is freely downloadable, and complete hardware plans are available, along with sources for custom parts.

Coaxial Cables for Martian Extreme Temperature Environments

NASA Technical Reports Server (NTRS)

Ramesham, Rajeshuni; Harvey, Wayne L.; Valas, Sam; Tsai, Michael C.

2011-01-01

Work was conducted to validate the use of the rover external flexible coaxial cabling for space under the extreme environments to be encountered during the Mars Science Laboratory (MSL) mission. The antennas must survive all ground operations plus the nominal 670-Martian-day mission that includes summer and winter seasons of the Mars environment. Successful development of processes established coaxial cable hardware fatigue limits, which were well beyond the expected in-flight exposures. In keeping with traditional qualification philosophy, this was accomplished by subjecting flight-representative coaxial cables to temperature cycling of the same depth as expected in-flight, but for three times the expected number of in-flight thermal cycles. Insertion loss and return loss tests were performed on the coaxial cables during the thermal chamber breaks. A vector network analyzer was calibrated and operated over the operational frequency range 7.145 to 8.450 GHz. Even though some of the exposed cables function only at UHF frequencies (approximately 400 MHz), the testing was more sensitive, and extending the test range down to 400 MHz would have cost frequency resolution. The Gore flexible coaxial cables, which were the subject of these tests, proved to be robust and displayed no sign of degradation due to the 3X exposure to the punishing Mars surface operations cycles.

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

Fang, X.; Xia, C.; Keppens, R.

We extend our earlier multidimensional, magnetohydrodynamic simulations of coronal rain occurring in magnetic arcades with higher resolution, grid-adaptive computations covering a much longer (>6 hr) time span. We quantify how blob-like condensations forming in situ grow along and across field lines and show that rain showers can occur in limit cycles, here demonstrated for the first time in 2.5D setups. We discuss dynamical, multi-dimensional aspects of the rebound shocks generated by the siphon inflows and quantify the thermodynamics of a prominence–corona transition-region-like structure surrounding the blobs. We point out the correlation between condensation rates and the cross-sectional size of loopmore » systems where catastrophic cooling takes place. We also study the variations of the typical number density, kinetic energy, and temperature while blobs descend, impact, and sink into the transition region. In addition, we explain the mechanisms leading to concurrent upflows while the blobs descend. As a result, there are plenty of shear flows generated with relative velocity difference around 80 km s{sup −1} in our simulations. These shear flows are siphon flows set up by multiple blob dynamics and they in turn affect the deformation of the falling blobs. In particular, we show how shear flows can break apart blobs into smaller fragments, within minutes.« less

Computational high-resolution optical imaging of the living human retina

NASA Astrophysics Data System (ADS)

Shemonski, Nathan D.; South, Fredrick A.; Liu, Yuan-Zhi; Adie, Steven G.; Scott Carney, P.; Boppart, Stephen A.

2015-07-01

High-resolution in vivo imaging is of great importance for the fields of biology and medicine. The introduction of hardware-based adaptive optics (HAO) has pushed the limits of optical imaging, enabling high-resolution near diffraction-limited imaging of previously unresolvable structures. In ophthalmology, when combined with optical coherence tomography, HAO has enabled a detailed three-dimensional visualization of photoreceptor distributions and individual nerve fibre bundles in the living human retina. However, the introduction of HAO hardware and supporting software adds considerable complexity and cost to an imaging system, limiting the number of researchers and medical professionals who could benefit from the technology. Here we demonstrate a fully automated computational approach that enables high-resolution in vivo ophthalmic imaging without the need for HAO. The results demonstrate that computational methods in coherent microscopy are applicable in highly dynamic living systems.

Impacts of wave-induced circulation in the surf zone on wave setup

NASA Astrophysics Data System (ADS)

Guérin, Thomas; Bertin, Xavier; Coulombier, Thibault; de Bakker, Anouk

2018-03-01

Wave setup corresponds to the increase in mean water level along the coast associated with the breaking of short-waves and is of key importance for coastal dynamics, as it contributes to storm surges and the generation of undertows. Although overall well explained by the divergence of the momentum flux associated with short waves in the surf zone, several studies reported substantial underestimations along the coastline. This paper investigates the impacts of the wave-induced circulation that takes place in the surf zone on wave setup, based on the analysis of 3D modelling results. A 3D phase-averaged modelling system using a vortex force formalism is applied to hindcast an unpublished field experiment, carried out at a dissipative beach under moderate to very energetic wave conditions (Hm 0 = 6m at breaking and Tp = 22s). When using an adaptive wave breaking parameterisation based on the beach slope, model predictions for water levels, short waves and undertows improved by about 30%, with errors reducing to 0.10 m, 0.10 m and 0.09 m/s, respectively. The analysis of model results suggests a very limited impact of the vertical circulation on wave setup at this dissipative beach. When extending this analysis to idealized simulations for different beach slopes ranging from 0.01 to 0.05, it shows that the contribution of the vertical circulation (horizontal and vertical advection and vertical viscosity terms) becomes more and more relevant as the beach slope increases. In contrast, for a given beach slope, the wave height at the breaking point has a limited impact on the relative contribution of the vertical circulation on the wave setup. For a slope of 0.05, the contribution of the terms associated with the vertical circulation accounts for up to 17% (i.e. a 20% increase) of the total setup at the shoreline, which provides a new explanation for the underestimations reported in previously published studies.

Unveiling the Gamma-Ray Source Count Distribution Below the Fermi Detection Limit with Photon Statistics

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

Zechlin, Hannes-S.; Cuoco, Alessandro; Donato, Fiorenza

The source-count distribution as a function of their flux, dN/dS, is one of the main quantities characterizing gamma-ray source populations. In this paper, we employ statistical properties of the Fermi Large Area Telescope (LAT) photon counts map to measure the composition of the extragalactic gamma-ray sky at high latitudes (|b| greater-than or slanted equal to 30°) between 1 and 10 GeV. We present a new method, generalizing the use of standard pixel-count statistics, to decompose the total observed gamma-ray emission into (a) point-source contributions, (b) the Galactic foreground contribution, and (c) a truly diffuse isotropic background contribution. Using the 6more » yr Fermi-LAT data set (P7REP), we show that the dN/dS distribution in the regime of so far undetected point sources can be consistently described with a power law with an index between 1.9 and 2.0. We measure dN/dS down to an integral flux of ~2 x 10 -11cm -2s -1, improving beyond the 3FGL catalog detection limit by about one order of magnitude. The overall dN/dS distribution is consistent with a broken power law, with a break at 2.1 +1.0 -1.3 x 10 -8cm -2s -1. The power-law index n 1 = 3.1 +0.7 -0.5 for bright sources above the break hardens to n 2 = 1.97 ± 0.03 for fainter sources below the break. A possible second break of the dN/dS distribution is constrained to be at fluxes below 6.4 x 10 -11cm -2s -1 at 95% confidence level. Finally, the high-latitude gamma-ray sky between 1 and 10 GeV is shown to be composed of ~25% point sources, ~69.3% diffuse Galactic foreground emission, and ~6% isotropic diffuse background.« less

[Effects of acupuncture on lactoferrin content in tears and tear secretion in patients suffering from dry eyes: a randomized controlled trial].

PubMed

Shi, Jing-lin; Miao, Wan-hong

2012-09-01

With the understanding of the immune inflammatory response in the pathogenesis of dry eyes, and the limitations of widely used artificial tears and numerous pharmaceuticals and methods to promote tear secretion, clinicians pay more attention to the therapies that can promote tear secretion actively. Acupuncture treatment for dry eye may meet this requirement. To observe the clinical efficacy of acupuncture treatment on dry eye and the effects on duration, and to examine the mechanisms of acupuncture in treating patients with dye eyes. The study was performed at Department of Ophthalmology, Shuguang Hospital, Shanghai University of Traditional Chinese Medicine from August 2010 to May 2011. Patients with the primary diagnosis of dry eye were enrolled. Sixty-five patients were randomly divided into treatment group and control group, and were given 3 weeks of acupuncture treatment or artificial tear therapy respectively. The enzyme-linked immunosorbent assay was used to detect the lactoferrin content of the tears before and after treatment. In order to evaluate the efficacy of the treatment methods, the Schirmer I test and break-up time were also measured. Compared with before treatment, the lactoferrin content in the tears of patients in the treatment group increased, break-up time was prolonged and the result of the Schirmer I test showed improvement after 3 weeks of treatment. The indexes mentioned above did not change in the control group after treatment. There were no significant differences in tear lactoferrin and Schirmer I test between one week after treatment and after 3-week treatment in the treatment group, but break-up time was significantly shortened. The result of Schirmer I test in the treatment group was significantly higher than that in the control group one week after treatment. Acupuncture can increase tear lactoferrin level, extend tear film break-up time and promote tear secretion in patients with dry eye in a time-limited trial. With the end of treatment, the effect decreased.