Science.gov

Sample records for allowing direct observation

  1. A medaka model of cancer allowing direct observation of transplanted tumor cells in vivo at a cellular-level resolution.

    PubMed

    Hasegawa, Sumitaka; Maruyama, Kouichi; Takenaka, Hikaru; Furukawa, Takako; Saga, Tsuneo

    2009-08-18

    The recent success with small fish as an animal model of cancer with the aid of fluorescence technique has attracted cancer modelers' attention because it would be possible to directly visualize tumor cells in vivo in real time. Here, we report a medaka model capable of allowing the observation of various cell behaviors of transplanted tumor cells, such as cell proliferation and metastasis, which were visualized easily in vivo. We established medaka melanoma (MM) cells stably expressing GFP and transplanted them into nonirradiated and irradiated medaka. The tumor cells were grown at the injection sites in medaka, and the spatiotemporal changes were visualized under a fluorescence stereoscopic microscope at a cellular-level resolution, and even at a single-cell level. Tumor dormancy and metastasis were also observed. Interestingly, in irradiated medaka, accelerated tumor growth and metastasis of the transplanted tumor cells were directly visualized. Our medaka model provides an opportunity to visualize in vivo tumor cells "as seen in a culture dish" and would be useful for in vivo tumor cell biology. PMID:19666513

  2. A medaka model of cancer allowing direct observation of transplanted tumor cells in vivo at a cellular-level resolution

    PubMed Central

    Hasegawa, Sumitaka; Maruyama, Kouichi; Takenaka, Hikaru; Furukawa, Takako; Saga, Tsuneo

    2009-01-01

    The recent success with small fish as an animal model of cancer with the aid of fluorescence technique has attracted cancer modelers' attention because it would be possible to directly visualize tumor cells in vivo in real time. Here, we report a medaka model capable of allowing the observation of various cell behaviors of transplanted tumor cells, such as cell proliferation and metastasis, which were visualized easily in vivo. We established medaka melanoma (MM) cells stably expressing GFP and transplanted them into nonirradiated and irradiated medaka. The tumor cells were grown at the injection sites in medaka, and the spatiotemporal changes were visualized under a fluorescence stereoscopic microscope at a cellular-level resolution, and even at a single-cell level. Tumor dormancy and metastasis were also observed. Interestingly, in irradiated medaka, accelerated tumor growth and metastasis of the transplanted tumor cells were directly visualized. Our medaka model provides an opportunity to visualize in vivo tumor cells “as seen in a culture dish” and would be useful for in vivo tumor cell biology. PMID:19666513

  3. Unraveling the electronic structure of azolehemiporphyrazines: direct spectroscopic observation of magnetic dipole allowed nature of the lowest π-π* transition of 20π-electron porphyrinoids.

    PubMed

    Muranaka, Atsuya; Ohira, Shino; Toriumi, Naoyuki; Hirayama, Machiko; Kyotani, Fumiko; Mori, Yukie; Hashizume, Daisuke; Uchiyama, Masanobu

    2014-06-26

    Hemiporphyrazines are a large family of phthalocyanine analogues in which two isoindoline units are replaced by other rings. Here we report unambiguous identification of 20π-electron structure of triazolehemiporphyrazines (1, 2) and thiazolehemiporphyrazine (3) by means of X-ray analysis, various spectroscopic methods, and density functional theory (DFT) calculations. The hemiporphyrazines were compared in detail with dibenzotetraazaporphyrin (4), a structurally related 18π-electron molecule. X-ray analysis revealed that tetrakis(2,6-dimethylphenyloxy)triazolehemiporphyrazine (1b) adopted planar geometry in the solid state. A weak absorption band with a pronounced vibronic progression, observed for all the hemiporphyrazines, was attributed to the lowest π-π* transition with the electric-dipole-forbidden nature. In the case of intrinsically chiral vanadyl triazolehemiporphyrazine (2), a large dissymmetry (g) factor was detected for the CD signal corresponding to the lowest π-π* transition with the magnetic-dipole-allowed nature. Molecular orbital analysis and NICS calculations showed that the azolehemiporphyrazines have a 20π-electron system with a weak paratropic ring current. PMID:24866729

  4. Periodic reversal of direction allows Myxobacteria to swarm

    PubMed Central

    Wu, Yilin; Kaiser, A. Dale; Jiang, Yi; Alber, Mark S.

    2009-01-01

    Many bacteria can rapidly traverse surfaces from which they are extracting nutrient for growth. They generate flat, spreading colonies, called swarms because they resemble swarms of insects. We seek to understand how members of any dense swarm spread efficiently while being able to perceive and interfere minimally with the motion of others. To this end, we investigate swarms of the myxobacterium, Myxococcus xanthus. Individual M. xanthus cells are elongated; they always move in the direction of their long axis; and they are in constant motion, repeatedly touching each other. Remarkably, they regularly reverse their gliding directions. We have constructed a detailed cell- and behavior-based computational model of M. xanthus swarming that allows the organization of cells to be computed. By using the model, we are able to show that reversals of gliding direction are essential for swarming and that reversals increase the outflow of cells across the edge of the swarm. Cells at the swarm edge gain maximum exposure to nutrient and oxygen. We also find that the reversal period predicted to maximize the outflow of cells is the same (within the errors of measurement) as the period observed in experiments with normal M. xanthus cells. This coincidence suggests that the circuit regulating reversals evolved to its current sensitivity under selection for growth achieved by swarming. Finally, we observe that, with time, reversals increase the cell alignment, and generate clusters of parallel cells. PMID:19164578

  5. Direct observation detonator operation

    NASA Astrophysics Data System (ADS)

    Hall, Charles R.

    2001-11-01

    The analysis of detonator-timing performance has involved the use of rotating-mirror cameras (RMC) used in the streak mode and high-speed film. Fiducial timing marks are applied to the film to provide temporal references. The use of a RMC for detonator analysis requires aligning the camera, performing an exposure test, capturing light from the detonation and then processing the film. This procedure can take up to an hour for two technicians. After the film is possessed another technician compares each light streak on the film with the fiducial timing marks also recorded on the film. Capturing light from a detonator and recording it directly to a digitizer can improve detonator-timing measurement in several ways. The digitized signals can then be directly analyzed with software. The direct recording method reduces the need for expensive rotating mirror cameras, film processing and subjective optical measurement comparison. Furthermore, an extensive support facility requiring several specialized technicians is reduced to a single technician in a modest laboratory. This technician is then capable of performing several tests an hour. Tests were preformed to measure light intensity at detonation. An optical method of capturing the light was designed using a remote microscope coupled to optical fiber to bring the light to an optical/electrical converter and a digitizer then records the signal. This system is presently used in parallel with a RMC. The results are compared for accuracy.

  6. Dipole-allowed direct band gap silicon superlattices

    NASA Astrophysics Data System (ADS)

    Oh, Young Jun; Lee, In-Ho; Kim, Sunghyun; Lee, Jooyoung; Chang, Kee Joo

    2015-12-01

    Silicon is the most popular material used in electronic devices. However, its poor optical properties owing to its indirect band gap nature limit its usage in optoelectronic devices. Here we present the discovery of super-stable pure-silicon superlattice structures that can serve as promising materials for solar cell applications and can lead to the realization of pure Si-based optoelectronic devices. The structures are almost identical to that of bulk Si except that defective layers are intercalated in the diamond lattice. The superlattices exhibit dipole-allowed direct band gaps as well as indirect band gaps, providing ideal conditions for the investigation of a direct-to-indirect band gap transition. The fact that almost all structural portions of the superlattices originate from bulk Si warrants their stability and good lattice matching with bulk Si. Through first-principles molecular dynamics simulations, we confirmed their thermal stability and propose a possible method to synthesize the defective layer through wafer bonding.

  7. Dipole-allowed direct band gap silicon superlattices

    PubMed Central

    Oh, Young Jun; Lee, In-Ho; Kim, Sunghyun; Lee, Jooyoung; Chang, Kee Joo

    2015-01-01

    Silicon is the most popular material used in electronic devices. However, its poor optical properties owing to its indirect band gap nature limit its usage in optoelectronic devices. Here we present the discovery of super-stable pure-silicon superlattice structures that can serve as promising materials for solar cell applications and can lead to the realization of pure Si-based optoelectronic devices. The structures are almost identical to that of bulk Si except that defective layers are intercalated in the diamond lattice. The superlattices exhibit dipole-allowed direct band gaps as well as indirect band gaps, providing ideal conditions for the investigation of a direct-to-indirect band gap transition. The fact that almost all structural portions of the superlattices originate from bulk Si warrants their stability and good lattice matching with bulk Si. Through first-principles molecular dynamics simulations, we confirmed their thermal stability and propose a possible method to synthesize the defective layer through wafer bonding. PMID:26656482

  8. Ovarian fluid allows directional cryptic female choice despite external fertilization.

    PubMed

    Alonzo, Suzanne H; Stiver, Kelly A; Marsh-Rollo, Susan E

    2016-01-01

    In species with internal fertilization, females can favour certain males over others, not only before mating but also within the female's reproductive tract after mating. Here, we ask whether such directional post-mating (that is, cryptic) female mate choice can also occur in species with external fertilization. Using an in vitro sperm competition experiment, we demonstrate that female ovarian fluid (ovarian fluid) changes the outcome of sperm competition by decreasing the importance of sperm number thereby increasing the relative importance of sperm velocity. We further show that ovarian fluid does not differentially affect sperm from alternative male phenotypes, but generally enhances sperm velocity, motility, straightness and chemoattraction. Under natural conditions, female ovarian fluid likely increases the paternity of the preferred parental male phenotype, as these males release fewer but faster sperm. These results imply females have greater control over fertilization and potential to exert selection on males in species with external fertilization than previously thought possible. PMID:27529581

  9. Ovarian fluid allows directional cryptic female choice despite external fertilization

    PubMed Central

    Alonzo, Suzanne H.; Stiver, Kelly A.; Marsh-Rollo, Susan E.

    2016-01-01

    In species with internal fertilization, females can favour certain males over others, not only before mating but also within the female's reproductive tract after mating. Here, we ask whether such directional post-mating (that is, cryptic) female mate choice can also occur in species with external fertilization. Using an in vitro sperm competition experiment, we demonstrate that female ovarian fluid (ovarian fluid) changes the outcome of sperm competition by decreasing the importance of sperm number thereby increasing the relative importance of sperm velocity. We further show that ovarian fluid does not differentially affect sperm from alternative male phenotypes, but generally enhances sperm velocity, motility, straightness and chemoattraction. Under natural conditions, female ovarian fluid likely increases the paternity of the preferred parental male phenotype, as these males release fewer but faster sperm. These results imply females have greater control over fertilization and potential to exert selection on males in species with external fertilization than previously thought possible. PMID:27529581

  10. Directional drilling allows quick exit from petrochemical plant

    SciTech Connect

    Halderman, R.G.

    1994-12-31

    Horizontal directional drilling uses specialty tools and techniques largely taken from the oil field and the mining industry to very accurately install pipelines, utilities and other conduits under obstacles such as rivers, beaches, environmentally sensitive areas, roadways, railroads, airfields, and congested pipeline corridors. In the early part of 1990, a particularly interesting problem confronted the pipeline engineers at Union Carbides 2,500-acre Seadrift plant near Port Lavaca, Texas. Having started up in 1954, the plant today is a major supplier of chemicals and plastics to industry, shipping more than two billion pounds per year. Since very large volumes of cooling water are needed for the operation of a petrochemical complex of this magnitude, years of expansion and modifications have caused the plant to become nearly surrounded by a number of rather large segmented ponds.

  11. Direct observation of time reversal violation

    NASA Astrophysics Data System (ADS)

    Bernabéu, J.

    2013-06-01

    A direct evidence for Time Reversal Violation (TRV) means an experiment that, considered by itself, clearly shows TRV independent of, and unconnected to, the results for CP Violation. No existing result before the recent BABAR experiment with entangled neutral B mesons had demonstrated TRV in this sense. There is a unique opportunity for a search of TRV with unstable particles thanks to the Einstein-Podolsky-Rosen (EPR) Entanglement between the two neutral mesons in B, and PHI, Factories. The two quantum effects of the first decay as a filtering measurement and the transfer of information to the still living partner allow performing a genuine TRV asymmetry with the exchange of "in" and "out" states. With four independent TRV asymmetries, BABAR observes a large deviation of T-invariance with a statistical significance of 14 standard deviations, far more than needed to declare the result as a discovery. This is the first direct observation of TRV in the time evolution of any system.

  12. 30 CFR 1220.011 - Schedule of allowable direct and allocable joint costs and credits.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... event of oil spills or other environmental damage are allowable. The costs of actual control and cleanup of oil spills and resulting responsibilities required by applicable laws and regulations are... PAYMENT FOR OUTER CONTINENTAL SHELF OIL AND GAS LEASES § 1220.011 Schedule of allowable direct...

  13. 30 CFR 1220.011 - Schedule of allowable direct and allocable joint costs and credits.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... event of oil spills or other environmental damage are allowable. The costs of actual control and cleanup of oil spills and resulting responsibilities required by applicable laws and regulations are... PAYMENT FOR OUTER CONTINENTAL SHELF OIL AND GAS LEASES § 1220.011 Schedule of allowable direct...

  14. 30 CFR 1220.011 - Schedule of allowable direct and allocable joint costs and credits.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... event of oil spills or other environmental damage are allowable. The costs of actual control and cleanup of oil spills and resulting responsibilities required by applicable laws and regulations are... PAYMENT FOR OUTER CONTINENTAL SHELF OIL AND GAS LEASES § 1220.011 Schedule of allowable direct...

  15. 30 CFR 220.011 - Schedule of allowable direct and allocable joint costs and credits.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... event of oil spills or other environmental damage are allowable. The costs of actual control and cleanup of oil spills and resulting responsibilities required by applicable laws and regulations are... PAYMENT FOR OUTER CONTINENTAL SHELF OIL AND GAS LEASES § 220.011 Schedule of allowable direct...

  16. Direct observation of microbial adhesion to membranes.

    PubMed

    Wang, Sunny; Guillen, Greg; Hoek, Eric M V

    2005-09-01

    Direct microscopic observation and an interfacial force model were used to better understand and control microbial adhesion to polymeric ultrafiltration membranes. The model was used to predict a "critical flux", below which cells deposited reversibly, and direct observation was used to visually quantify cell deposition and removal. In preliminary direct observation experiments, permeate reversal (backpulsing) was more effective than cross-flow hydrodynamics at removing deposited cells. In experiments conducted below the critical flux, no cell accumulation was observed over repeated forward-reverse filtration cycles; however, a small fraction of cells deposited irreversibly regardless of the flux, membrane, or solution chemistry. The fraction of irreversibly deposited cells was consistent with the equilibrium surface coverage attained without permeation (i.e., due to heterogeneous adsorption). Although steric forces were not invoked to establish a critical flux, when operating above the critical flux, a balance between permeation drag and steric repulsion appeared to determine the strength of adhesion of cells to membranes. Direct observation also confirmed that above the critical flux fouling occurred and pressure losses accumulated over several backpulse cycles, whereas below the critical flux there were no observable pressure losses or fouling. PMID:16190200

  17. Direct Observation: Assessing Orthopaedic Trainee Competence in the Ambulatory Setting.

    PubMed

    Phillips, Donna P; Zuckerman, Joseph D; Kalet, Adina; Egol, Kenneth A

    2016-09-01

    The Accreditation Council of Graduate Medical Education requires that residency programs teach and assess trainees in six core competencies. Assessments are imperative to determine trainee competence and to ensure that excellent care is provided to all patients. A structured, direct observation program is feasible for assessing nontechnical core competencies and providing trainees with immediate constructive feedback. Direct observation of residents in the outpatient setting by trained faculty allows assessment of each core competency. Checklists are used to document residents' basic communication skills, clinical reasoning, physical examination methods, and medical record keeping. Faculty concerns regarding residents' professionalism, medical knowledge, fatigue, or ability to self-assess are tracked. Serial observations allow for the reinforcement and/or monitoring of skills and attitudes identified as needing improvement. Residents who require additional coaching are identified early in training. Progress in educational milestones is recorded, allowing an individualized educational program that ensures that future orthopaedic surgeons excel across all domains of medical and surgical competence. PMID:27479831

  18. Current observations with a decaying cosmological constant allow for chaotic cyclic cosmology

    NASA Astrophysics Data System (ADS)

    Ellis, George F. R.; Platts, Emma; Sloan, David; Weltman, Amanda

    2016-04-01

    We use the phase plane analysis technique of Madsen and Ellis [1] to consider a universe with a true cosmological constant as well as a cosmological "constant" that is decaying. Time symmetric dynamics for the inflationary era allows eternally bouncing models to occur. Allowing for scalar field dynamic evolution, we find that if dark energy decays in the future, chaotic cyclic universes exist provided the spatial curvature is positive. This is particularly interesting in light of current observations which do not yet rule out either closed universes or possible evolution of the cosmological constant. We present only a proof of principle, with no definite claim on the physical mechanism required for the present dark energy to decay.

  19. Direct observation limits on antimatter gravitation

    SciTech Connect

    Fischler, Mark; Lykken, Joe; Roberts, Tom; /Fermilab

    2008-06-01

    The proposed Antihydrogen Gravity experiment at Fermilab (P981) will directly measure the gravitational attraction g between antihydrogen and the Earth, with an accuracy of 1% or better. The following key question has been asked by the PAC: Is a possible 1% difference between g and g already ruled out by other evidence? This memo presents the key points of existing evidence, to answer whether such a difference is ruled out (a) on the basis of direct observational evidence; and/or (b) on the basis of indirect evidence, combined with reasoning based on strongly held theoretical assumptions. The bottom line is that there are no direct observations or measurements of gravitational asymmetry which address the antimatter sector. There is evidence which by indirect reasoning can be taken to rule out such a difference, but the analysis needed to draw that conclusion rests on models and assumptions which are in question for other reasons and are thus worth testing. There is no compelling evidence or theoretical reason to rule out such a difference at the 1% level.

  20. Transgenic, Fluorescent Leishmania mexicana Allow Direct Analysis of the Proteome of Intracellular Amastigotes*S⃞

    PubMed Central

    Paape, Daniel; Lippuner, Christoph; Schmid, Monika; Ackermann, Renate; Barrios-Llerena, Martin E.; Zimny-Arndt, Ursula; Brinkmann, Volker; Arndt, Benjamin; Pleissner, Klaus Peter; Jungblut, Peter R.; Aebischer, Toni

    2008-01-01

    Investigating the proteome of intracellular pathogens is often hampered by inadequate methodologies to purify the pathogen free of host cell material. This has also precluded direct proteome analysis of the intracellular, amastigote form of Leishmania spp., protozoan parasites that cause a spectrum of diseases that affect some 12 million patients worldwide. Here a method is presented that combines classic, isopycnic density centrifugation with fluorescent particle sorting for purification by exploiting transgenic, fluorescent parasites to allow direct proteome analysis of the purified organisms. By this approach the proteome of intracellular Leishmania mexicana amastigotes was compared with that of extracellular promastigotes that are transmitted by insect vectors. In total, 509 different proteins were identified by mass spectrometry and database search. This number corresponds to ∼6% of gene products predicted from the reference genome of Leishmania major. Intracellular amastigotes synthesized significantly more proteins with basic pI and showed a greater abundance of enzymes of fatty acid catabolism, which may reflect their living in acidic habitats and metabolic adaptation to nutrient availability, respectively. Bioinformatics analyses of the genes corresponding to the protein data sets produced clear evidence for skewed codon usage and translational bias in these organisms. Moreover analysis of the subset of genes whose products were more abundant in amastigotes revealed characteristic sequence motifs in 3′-untranslated regions that have been linked to translational control elements. This suggests that proteome data sets may be used to identify regulatory elements in mRNAs. Last but not least, at 6% coverage the proteome identified all vaccine antigens tested to date. Thus, the present data set provides a valuable resource for selection of candidate vaccine antigens. PMID:18474515

  1. Directly observed therapy for treating tuberculosis

    PubMed Central

    Karumbi, Jamlick; Garner, Paul

    2015-01-01

    Background Tuberculosis (TB) requires at least six months of treatment. If treatment is incomplete, patients may not be cured and drug resistance may develop. Directly Observed Therapy (DOT) is a specific strategy, endorsed by the World Health Organization, to improve adherence by requiring health workers, community volunteers or family members to observe and record patients taking each dose. Objectives To evaluate DOT compared to self-administered therapy in people on treatment for active TB or on prophylaxis to prevent active disease. We also compared the effects of different forms of DOT. Search methods We searched the following databases up to 13 January 2015: the Cochrane Infectious Diseases Group Specialized Register; the Cochrane Central Register of Controlled Trials (CENTRAL), published in the Cochrane Library; MEDLINE; EMBASE; LILACS and mRCT. We also checked article reference lists and contacted relevant researchers and organizations. Selection criteria Randomized controlled trials (RCTs) and quasi-RCTs comparing DOT with routine self-administration of treatment or prophylaxis at home. Data collection and analysis Two review authors independently assessed risk of bias of each included trial and extracted data. We compared interventions using risk ratios (RR) with 95% confidence intervals (CI). We used a random-effects model if meta-analysis was appropriate but heterogeneity present (I2 statistic = 50%). We assessed the quality of the evidence using the GRADE approach. Main results Eleven trials including 5662 participants met the inclusion criteria. DOT was performed by a range of people (nurses, community health workers, family members or former TB patients) in a variety of settings (clinic, the patient's home or the home of a community volunteer). DOT versus self-administered Six trials from South Africa, Thailand, Taiwan, Pakistan and Australia compared DOT with self-administered therapy for treatment. Trials included DOT at home by family members

  2. Direct observation of laser guided corona discharges.

    PubMed

    Wang, Tie-Jun; Wei, Yingxia; Liu, Yaoxiang; Chen, Na; Liu, Yonghong; Ju, Jingjing; Sun, Haiyi; Wang, Cheng; Lu, Haihe; Liu, Jiansheng; Chin, See Leang; Li, Ruxin; Xu, Zhizhan

    2015-01-01

    Laser based lightning control holds a promising way to solve the problem of the long standing disaster of lightning strikes. But it is a challenging project due to insufficient understanding of the interaction between laser plasma channel and high voltage electric filed. In this work, a direct observation of laser guided corona discharge is reported. Laser filament guided streamer and leader types of corona discharges were observed. An enhanced ionization took place in the leader (filament) through the interaction with the high voltage discharging field. The fluorescence lifetime of laser filament guided corona discharge was measured to be several microseconds, which is 3 orders of magnitude longer than the fluorescence lifetime of laser filaments. This work could be advantageous towards a better understanding of laser assisted leader development in the atmosphere. PMID:26679271

  3. First direct observation of muon antineutrino disappearance

    DOE PAGESBeta

    Adamson, P.

    2011-07-05

    This letter reports the first direct observation of muon antineutrino disappearance. The MINOS experiment has taken data with an accelerator beam optimized for ν¯μ production, accumulating an exposure of 1.71 x 1020 protons on target. In the Far Detector, 97 charged current ν¯μ events are observed. The no-oscillation hypothesis predicts 156 events and is excluded at 6.3σ. The best fit to oscillation yields |Δm¯2| = (3.36-0.40 +0.46(stat.) ± 0.06(syst.)) x 10-3 eV2, sin2(2 θ¯) = 0.86-0.12+0.11 (stat.) ± 0.01(syst.). The MINOS νμ and ν¯μ measurements are consistent at the 2.0% confidence level, assuming identical underlying oscillation parameters.

  4. Direct observation of laser guided corona discharges

    NASA Astrophysics Data System (ADS)

    Wang, Tie-Jun; Wei, Yingxia; Liu, Yaoxiang; Chen, Na; Liu, Yonghong; Ju, Jingjing; Sun, Haiyi; Wang, Cheng; Lu, Haihe; Liu, Jiansheng; Chin, See Leang; Li, Ruxin; Xu, Zhizhan

    2015-12-01

    Laser based lightning control holds a promising way to solve the problem of the long standing disaster of lightning strikes. But it is a challenging project due to insufficient understanding of the interaction between laser plasma channel and high voltage electric filed. In this work, a direct observation of laser guided corona discharge is reported. Laser filament guided streamer and leader types of corona discharges were observed. An enhanced ionization took place in the leader (filament) through the interaction with the high voltage discharging field. The fluorescence lifetime of laser filament guided corona discharge was measured to be several microseconds, which is 3 orders of magnitude longer than the fluorescence lifetime of laser filaments. This work could be advantageous towards a better understanding of laser assisted leader development in the atmosphere.

  5. Direct observation of laser guided corona discharges

    PubMed Central

    Wang, Tie-Jun; Wei, Yingxia; Liu, Yaoxiang; Chen, Na; Liu, Yonghong; Ju, Jingjing; Sun, Haiyi; Wang, Cheng; Lu, Haihe; Liu, Jiansheng; Chin, See Leang; Li, Ruxin; Xu, Zhizhan

    2015-01-01

    Laser based lightning control holds a promising way to solve the problem of the long standing disaster of lightning strikes. But it is a challenging project due to insufficient understanding of the interaction between laser plasma channel and high voltage electric filed. In this work, a direct observation of laser guided corona discharge is reported. Laser filament guided streamer and leader types of corona discharges were observed. An enhanced ionization took place in the leader (filament) through the interaction with the high voltage discharging field. The fluorescence lifetime of laser filament guided corona discharge was measured to be several microseconds, which is 3 orders of magnitude longer than the fluorescence lifetime of laser filaments. This work could be advantageous towards a better understanding of laser assisted leader development in the atmosphere. PMID:26679271

  6. Diffuse x-rays: directly observing dark matter?

    SciTech Connect

    Forbes, Michael McNeil; Zhitnitsky, Ariel R E-mail: arz@physics.ubc.ca

    2008-01-15

    Several independent observations of the galactic core suggest hitherto unexplained sources of energy. We suggest that dark matter in the form of dense antimatter nuggets could provide a natural site for electron and proton annihilation, providing 511 keV photons, gamma rays, and diffuse keV x-ray radiation. We show that identifying dark matter as antimatter nuggets is consistent with the observed emissions, and we make definite predictions about their spectrum and morphology. If correct, our proposal not only identifies dark matter and explains baryogenesis, but also allows x-ray observations to directly probe the matter distribution in our galaxy.

  7. Direct Observation of Sub-Binomial Light

    NASA Astrophysics Data System (ADS)

    Bartley, Tim J.; Donati, Gaia; Jin, Xian-Min; Datta, Animesh; Barbieri, Marco; Walmsley, Ian A.

    2013-04-01

    Nonclassical states of light are necessary resources for quantum technologies such as cryptography, computation and the definition of metrological standards. Observing signatures of nonclassicality generally requires inferring either the photon number distribution or a quasiprobability distribution indirectly from a set of measurements. Here, we report an experiment in which the nonclassical character of families of quantum states is assessed by direct inspection of the outcomes from a multiplexed photon counter. This scheme does not register the actual photon number distribution; the statistics of the detector clicks alone serve as a witness of nonclassicality, as proposed by Sperling et al. [Phys. Rev. Lett. 109, 093601 (2012)]. Our work paves a way for the practical characterization of increasingly sophisticated states and detectors.

  8. Recursive directional ligation by plasmid reconstruction allows rapid and seamless cloning of oligomeric genes.

    PubMed

    McDaniel, Jonathan R; Mackay, J Andrew; Quiroz, Felipe García; Chilkoti, Ashutosh

    2010-04-12

    This paper reports a new strategy, recursive directional ligation by plasmid reconstruction (PRe-RDL), to rapidly clone highly repetitive polypeptides of any sequence and specified length over a large range of molecular weights. In a single cycle of PRe-RDL, two halves of a parent plasmid, each containing a copy of an oligomer, are ligated together, thereby dimerizing the oligomer and reconstituting a functional plasmid. This process is carried out recursively to assemble an oligomeric gene with the desired number of repeats. PRe-RDL has several unique features that stem from the use of type IIs restriction endonucleases: first, PRe-RDL is a seamless cloning method that leaves no extraneous nucleotides at the ligation junction. Because it uses type IIs endonucleases to ligate the two halves of the plasmid, PRe-RDL also addresses the major limitation of RDL in that it abolishes any restriction on the gene sequence that can be oligomerized. The reconstitution of a functional plasmid only upon successful ligation in PRe-RDL also addresses two other limitations of RDL: the significant background from self-ligation of the vector observed in RDL, and the decreased efficiency of ligation due to nonproductive circularization of the insert. PRe-RDL can also be used to assemble genes that encode different sequences in a predetermined order to encode block copolymers or append leader and trailer peptide sequences to the oligomerized gene. PMID:20184309

  9. WMAP haze: Directly observing dark matter?

    SciTech Connect

    Forbes, Michael McNeil; Zhitnitsky, Ariel R.

    2008-10-15

    In this paper, we show that dark matter in the form of dense matter/antimatter nuggets could provide a natural and unified explanation for several distinct bands of diffuse radiation from the core of the Galaxy spanning over 13 orders of magnitude in frequency. We fix all of the phenomenological properties of this model by matching to x-ray observations in the keV band, and then calculate the unambiguously predicted thermal emission in the microwave band, at frequencies smaller by 11 orders of magnitude. Remarkably, the intensity and spectrum of the emitted thermal radiation are consistent with - and could entirely explain - the so-called 'WMAP haze': a diffuse microwave excess observed from the core of our Galaxy by the Wilkinson Microwave Anisotropy Probe (WMAP). This provides another strong constraint of our proposal, and a remarkable nontrivial validation. If correct, our proposal identifies the nature of the dark matter, explains baryogenesis, and provides a means to directly probe the matter distribution in our Galaxy by analyzing several different types of diffuse emissions.

  10. First direct observation of muon antineutrino disappearance

    SciTech Connect

    Adamson, P.

    2011-07-05

    This letter reports the first direct observation of muon antineutrino disappearance. The MINOS experiment has taken data with an accelerator beam optimized for ν¯μ production, accumulating an exposure of 1.71 x 1020 protons on target. In the Far Detector, 97 charged current ν¯μ events are observed. The no-oscillation hypothesis predicts 156 events and is excluded at 6.3σ. The best fit to oscillation yields |Δm¯2| = (3.36-0.40 +0.46(stat.) ± 0.06(syst.)) x 10-3 eV2, sin2(2 θ¯) = 0.86-0.12+0.11 (stat.) ± 0.01(syst.). The MINOS νμ and ν¯μ measurements are consistent at the 2.0% confidence level, assuming identical underlying oscillation parameters.

  11. 30 CFR 1220.011 - Schedule of allowable direct and allocable joint costs and credits.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... event of oil spills or other environmental damage are allowable. The costs of actual control and cleanup of oil spills and resulting responsibilities required by applicable laws and regulations are... DETERMINING NET PROFIT SHARE PAYMENT FOR OUTER CONTINENTAL SHELF OIL AND GAS LEASES § 1220.011 Schedule...

  12. Direct observation of amyloid nucleation under nanomechanical stretching

    NASA Astrophysics Data System (ADS)

    Varongchayakul, Nitinun

    Self-assembly of amyloid nanofiber is associated with functional and pathological processes such as in neurodegenerative diseases. Despite intensive studies, stochastic nature of the process has made it difficult to elucidate molecular mechanisms for the key amyloid nucleation. Here, we investigated the amyloid nucleation of silk-elastin-like peptide (SELP) using time-lapse lateral force microscopy (LFM). By repeated scanning a single line on a SELP-coated mica surface, we observed sudden stepwise height increases, corresponds to nucleation of an amyloid fiber. The lateral force profiles followed either a worm-like chain model or an exponential function, suggesting that the atomic force microscopy (AFM) tip stretches a single or multiple SELP molecules along the scanning direction, serves as the template for further self-assembly perpendicular to the scan direction. Such mechanically induced nucleation of amyloid fibrils allows positional and directional control of amyloid assembly in vitro , which we demonstrate by generating single nanofibers at predetermined nucleation sites.

  13. Prediction of direct band gap silicon superlattices with dipole-allowed optical transition

    NASA Astrophysics Data System (ADS)

    Kim, Sunghyun; Oh, Young Jun; Lee, In-Ho; Lee, Jooyoung; Chang, K. J.

    While cubic diamond silicon (c-Si) is an important element in electronic devices, it has poor optical properties owing to its indirect gap nature, thereby limiting its applications to optoelectronic devices. Here, we report Si superlattice structures which are computationally designed to possess direct band gaps and excellent optical properties. The computational approach adopts density functional calculations and conformational space annealing for global optimization. The Si superlattices, which consist of alternating stacks of Si(111) layers and a defective layer with Seiwatz chains, have either direct or quasi-direct band gaps depending on the details of attacking layers. The photovoltaic efficiencies are calculated by solving Bethe-Salpeter equation together with quasiparticle G0W0 calculations. The strong direct optical transition is attributed to the overlap of the valence and conduction band edge states in the interface region. Our Si superlattices exhibit high thermal stability, with the energies lower by an order of magnitude than those of the previously reported Si allotropes. We discuss a possible route to the synthesis of the superlattices through wafer bonding. This work is supported by Samsung Science and Technology Foundation under Grant No. SSTF-BA1401-08.

  14. A General Ligand Design for Gold Catalysis allowing Ligand-Directed Anti Nucleophilic Attack of Alkynes

    PubMed Central

    Wang, Yanzhao; Wang, Zhixun; Li, Yuxue; Wu, Gongde; Cao, Zheng; Zhang, Liming

    2014-01-01

    Most homogenous gold catalyses demand ≥0.5 mol % catalyst loading. Due to the high cost of gold, these reactions are unlikely to be applicable in medium or large scale applications. Here we disclose a novel ligand design based on the privileged biphenyl-2-phosphine framework that offers a potentially general approach to dramatically lowering catalyst loading. In this design, an amide group at the 3’ position of the ligand framework directs and promotes nucleophilic attack at the ligand gold complex-activated alkyne, which is unprecedented in homogeneous gold catalysis considering the spatial challenge of using ligand to reach antiapproaching nucleophile in a linear P-Au-alkyne centroid structure. With such a ligand, the gold(I) complex becomes highly efficient in catalyzing acid addition to alkynes, with a turnover number up to 99,000. Density functional theory calculations support the role of the amide moiety in directing the attack of carboxylic acid via hydrogen bonding. PMID:24704803

  15. Trehalose glycopolymer resists allow direct writing of protein patterns by electron-beam lithography

    NASA Astrophysics Data System (ADS)

    Bat, Erhan; Lee, Juneyoung; Lau, Uland Y.; Maynard, Heather D.

    2015-03-01

    Direct-write patterning of multiple proteins on surfaces is of tremendous interest for a myriad of applications. Precise arrangement of different proteins at increasingly smaller dimensions is a fundamental challenge to apply the materials in tissue engineering, diagnostics, proteomics and biosensors. Herein, we present a new resist that protects proteins during electron-beam exposure and its application in direct-write patterning of multiple proteins. Polymers with pendant trehalose units are shown to effectively crosslink to surfaces as negative resists, while at the same time providing stabilization to proteins during the vacuum and electron-beam irradiation steps. In this manner, arbitrary patterns of several different classes of proteins such as enzymes, growth factors and immunoglobulins are realized. Utilizing the high-precision alignment capability of electron-beam lithography, surfaces with complex patterns of multiple proteins are successfully generated at the micrometre and nanometre scale without requiring cleanroom conditions.

  16. Roughness determination by direct visual observation of the speckle pattern

    NASA Astrophysics Data System (ADS)

    Rebollo, M. A.; Landau, M. R.; Hogert, E. N.; Gaggioli, N. G.; Muramatsu, M.

    1995-12-01

    There are mechanical and optical methods of measuring the roughness of surfaces. Mechanical methods are of a destructive type, while optical methods, although they are non-destructive, involve relatively complex systems and calculations. In this work a simple method is introduced, which allows one—through the direct observation of the speckle pattern—to make a visual correlation, comparing the first pattern with others obtained when the beam incidence angle varies. With this method it is possible to obtain results with acceptable accuracy for many industrial uses.

  17. Tagging motor memories with transcranial direct current stimulation allows later artificially-controlled retrieval

    PubMed Central

    Nozaki, Daichi; Yokoi, Atsushi; Kimura, Takahiro; Hirashima, Masaya; Orban de Xivry, Jean-Jacques

    2016-01-01

    We demonstrate that human motor memories can be artificially tagged and later retrieved by noninvasive transcranial direct current stimulation (tDCS). Participants learned to adapt reaching movements to two conflicting dynamical environments that were each associated with a different tDCS polarity (anodal or cathodal tDCS) on the sensorimotor cortex. That is, we sought to determine whether divergent background activity levels within the sensorimotor cortex (anodal: higher activity; cathodal: lower activity) give rise to distinct motor memories. After a training session, application of each tDCS polarity automatically resulted in the retrieval of the motor memory corresponding to that polarity. These results reveal that artificial modulation of neural activity in the sensorimotor cortex through tDCS can act as a context for the formation and recollection of motor memories. DOI: http://dx.doi.org/10.7554/eLife.15378.001 PMID:27472899

  18. Tagging motor memories with transcranial direct current stimulation allows later artificially-controlled retrieval.

    PubMed

    Nozaki, Daichi; Yokoi, Atsushi; Kimura, Takahiro; Hirashima, Masaya; Orban de Xivry, Jean-Jacques

    2016-01-01

    We demonstrate that human motor memories can be artificially tagged and later retrieved by noninvasive transcranial direct current stimulation (tDCS). Participants learned to adapt reaching movements to two conflicting dynamical environments that were each associated with a different tDCS polarity (anodal or cathodal tDCS) on the sensorimotor cortex. That is, we sought to determine whether divergent background activity levels within the sensorimotor cortex (anodal: higher activity; cathodal: lower activity) give rise to distinct motor memories. After a training session, application of each tDCS polarity automatically resulted in the retrieval of the motor memory corresponding to that polarity. These results reveal that artificial modulation of neural activity in the sensorimotor cortex through tDCS can act as a context for the formation and recollection of motor memories. PMID:27472899

  19. 46 CFR 148.03-3 - Direction and observation.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 5 2010-10-01 2010-10-01 false Direction and observation. 148.03-3 Section 148.03-3... HAZARDOUS MATERIALS IN BULK Minimum Transportation Requirements § 148.03-3 Direction and observation... be conducted only under the direction and observation of a person assigned or employed for such...

  20. Direct Observation of Paramagnons in Palladium

    SciTech Connect

    Doubble, R.; Hayden, S M.; Dai, Pengcheng; Mook Jr, Herbert A; Thompson, James R; Frost, C.

    2010-01-01

    We report an inelastic neutron scattering study of the spin fluctuations in the nearly ferromagnetic element palladium. Dispersive over-damped collective magnetic excitations or 'paramagnons' are observed up to 128 meV. We analyze our results in terms of a Moriya-Lonzarich-type spin-fluctuation model and estimate the contribution of the spin fluctuations to the low-temperature heat capacity. In spite of the paramagnon excitations being relatively strong, their relaxation rates are large. This leads to a small contribution to the low-temperature electronic specific heat.

  1. Direct observation of ballistic Andreev reflection

    SciTech Connect

    Klapwijk, T. M.; Ryabchun, S. A.

    2014-12-15

    An overview is presented of experiments on ballistic electrical transport in inhomogeneous superconducting systems which are controlled by the process of Andreev reflection. The initial experiments based on the coexistence of a normal phase and a superconducting phase in the intermediate state led to the concept itself. It was followed by a focus on geometrically inhomogeneous systems like point contacts, which provided a very clear manifestation of the energy and direction dependence of the Andreev reflection process. The point contacts have recently evolved towards the atomic scale owing to the use of mechanical break-junctions, revealing a very detailed dependence of Andreev reflection on the macroscopic phase of the superconducting state. In present-day research, the superconducting in homogeneity is constructed by clean room technology and combines superconducting materials, for example, with low-dimensional materials and topological insulators. Alternatively, the superconductor is combined with nano-objects, such as graphene, carbon nanotubes, or semiconducting nanowires. Each of these “inhomogeneous systems” provides a very interesting range of properties, all rooted in some manifestation of Andreev reflection.

  2. Relaxed Observance of Traditional Marriage Rules Allows Social Connectivity without Loss of Genetic Diversity.

    PubMed

    Guillot, Elsa G; Hazelton, Martin L; Karafet, Tatiana M; Lansing, J Stephen; Sudoyo, Herawati; Cox, Murray P

    2015-09-01

    Marriage rules, the community prescriptions that dictate who an individual can or cannot marry, are extremely diverse and universally present in traditional societies. A major focus of research in the early decades of modern anthropology, marriage rules impose social and economic forces that help structure societies and forge connections between them. However, in those early anthropological studies, the biological benefits or disadvantages of marriage rules could not be determined. We revisit this question by applying a novel simulation framework and genome-wide data to explore the effects of Asymmetric Prescriptive Alliance, an elaborate set of marriage rules that has been a focus of research for many anthropologists. Simulations show that strict adherence to these marriage rules reduces genetic diversity on the autosomes, X chromosome and mitochondrial DNA, but relaxed compliance produces genetic diversity similar to random mating. Genome-wide data from the Indonesian community of Rindi, one of the early study populations for Asymmetric Prescriptive Alliance, are more consistent with relaxed compliance than strict adherence. We therefore suggest that, in practice, marriage rules are treated with sufficient flexibility to allow social connectivity without significant degradation of biological diversity. PMID:25968961

  3. Relaxed Observance of Traditional Marriage Rules Allows Social Connectivity without Loss of Genetic Diversity

    PubMed Central

    Guillot, Elsa G.; Hazelton, Martin L.; Karafet, Tatiana M.; Lansing, J. Stephen; Sudoyo, Herawati; Cox, Murray P.

    2015-01-01

    Marriage rules, the community prescriptions that dictate who an individual can or cannot marry, are extremely diverse and universally present in traditional societies. A major focus of research in the early decades of modern anthropology, marriage rules impose social and economic forces that help structure societies and forge connections between them. However, in those early anthropological studies, the biological benefits or disadvantages of marriage rules could not be determined. We revisit this question by applying a novel simulation framework and genome-wide data to explore the effects of Asymmetric Prescriptive Alliance, an elaborate set of marriage rules that has been a focus of research for many anthropologists. Simulations show that strict adherence to these marriage rules reduces genetic diversity on the autosomes, X chromosome and mitochondrial DNA, but relaxed compliance produces genetic diversity similar to random mating. Genome-wide data from the Indonesian community of Rindi, one of the early study populations for Asymmetric Prescriptive Alliance, are more consistent with relaxed compliance than strict adherence. We therefore suggest that, in practice, marriage rules are treated with sufficient flexibility to allow social connectivity without significant degradation of biological diversity. PMID:25968961

  4. Bonding of SU-8 to glass for gastight picoliter reactors allowing in situ optical observation

    NASA Astrophysics Data System (ADS)

    Petrova, Elena V.; Aich, Anupam; Byington, Michael C.; Vekilov, Peter G.

    2013-10-01

    Experimental tasks in chemistry and biology require large experiment statistics, small solution volumes, and no gas or vapor exchange with the environment. Microfluidics devices built of the epoxy-based polymer SU-8 comply with these requirements. However, the additional constraints of reactor thickness of several micrometers, localized temperature control, and optical access for high-resolution observation provide a challenge. We developed a device consisting of top and bottom glass plates separated by a layer of cross-linked SU-8, with a resistive microheater deposited at the bottom. Picoliter reactor volumes are achieved by suspending aqueous solution droplets in silicone oil held in a channel with cross-section 5 × 40 µm2. The narrow channels lead to large capillary resistance and, in turn, high injection pressures. To achieve bonding of SU-8 to glass capable of withstanding such pressures, we optimized the oxygen plasma treatment of the polymer surface by monitoring the evolution of the treated surface with atomic force microscopy. We found that the plasma effect was fully determined by its power. The hydrophilicity of the treated surfaces was characterized by their contact angles with water. The treated surfaces were bonded to glass bottoms using a torque-controlled clamp with a 3 µm smoothness of the holding plates. The bonding pressure and temperature were chosen in the gap between those for the glass transition of the SU-8 layer and fracture of the glass bottom.

  5. Emerging feed-forward inhibition allows the robust formation of direction selectivity in the developing ferret visual cortex

    PubMed Central

    Escobar, Gina M.; Maffei, Arianna; Miller, Paul

    2014-01-01

    The computation of direction selectivity requires that a cell respond to joint spatial and temporal characteristics of the stimulus that cannot be separated into independent components. Direction selectivity in ferret visual cortex is not present at the time of eye opening but instead develops in the days and weeks following eye opening in a process that requires visual experience with moving stimuli. Classic Hebbian or spike timing-dependent modification of excitatory feed-forward synaptic inputs is unable to produce direction-selective cells from unselective or weakly directionally biased initial conditions because inputs eventually grow so strong that they can independently drive cortical neurons, violating the joint spatial-temporal activation requirement. Furthermore, without some form of synaptic competition, cells cannot develop direction selectivity in response to training with bidirectional stimulation, as cells in ferret visual cortex do. We show that imposing a maximum lateral geniculate nucleus (LGN)-to-cortex synaptic weight allows neurons to develop direction-selective responses that maintain the requirement for joint spatial and temporal activation. We demonstrate that a novel form of inhibitory plasticity, postsynaptic activity-dependent long-term potentiation of inhibition (POSD-LTPi), which operates in the developing cortex at the time of eye opening, can provide synaptic competition and enables robust development of direction-selective receptive fields with unidirectional or bidirectional stimulation. We propose a general model of the development of spatiotemporal receptive fields that consists of two phases: an experience-independent establishment of initial biases, followed by an experience-dependent amplification or modification of these biases via correlation-based plasticity of excitatory inputs that compete against gradually increasing feed-forward inhibition. PMID:24598528

  6. New direct Overflow Observations at the Denmark Strait Sill

    NASA Astrophysics Data System (ADS)

    Macrander, A.; Send, U.; Kaese, R. H.

    2003-04-01

    As a key region of the global thermohaline circulation, the Denmark Strait between Iceland and Greenland is the pathway for the densest component of the North Atlantic Deep Water, the Denmark Strait Overflow Water (DSOW). Since 1999, it has been probed with acoustic instruments in the SFB 460 program lead by the Institut f&{uml;u}r Meereskunde Kiel. The data from bottom Pressure/ Inverted Echo Sounders (PIES) and ADCP current profilers, deployed in a model-optimized mooring array at the Denmark Strait sill, resolve both spatial and temporal variability of the overflow. After recovery of moorings in August 2002, the time series available have a total length of 27 months. The data allow for transport estimates based on direct ADCP measurements and integrating geostrophic PIES observations. Including model comparisons, a mean DSOW transport of 3.0 Sv is calculated with an accuracy of ± 0.1 Sv. A statistical analysis with autoregressive moving average models has improved the information about integral time scales and dominant frequencies of the overflow variability. Until now, estimates of the mean DSOW throughflow have been remarkably stable. The PIES observations show a close correlation between sea surface height anomalies and the DSOW plume thickness. This opens a perspective for long term monitoring by remote sensing with relevance for climate change. First comparisons of in-situ measurements and satellite altimetry are presented.

  7. Direct observations of field-induced assemblies in magnetite ferrofluids

    PubMed Central

    Mousavi, N. S. Susan

    2015-01-01

    Evolution of microstructures in magnetite-based ferrofluids with weak dipolar moments (particle size ≤ 10 nm) is studied with an emphasis on examining the effects of particle concentration (ϕ) and magnetic field strength (H) on the structures. Nanoparticles are dispersed in water at three different concentrations, ϕ = 0.15%, 0.48%, and 0.59% (w/v) [g/ml%] and exposed to uniform magnetic fields in the range of H = 0.05–0.42 T. Cryogenic transmission electron microscopy is employed to provide in-situ observations of the field-induced assemblies in such systems. As the magnetic field increases, the Brownian colloids are observed to form randomly distributed chains aligned in the field direction, followed by head-to-tail chain aggregation and then lateral aggregation of chains termed as zippering. By increasing the field in low concentration samples, the number of chains increases, though their length does not change dramatically. Increasing concentration increases the length of the linear particle assemblies in the presence of a fixed external magnetic field. Thickening of the chains due to zippering is observed at relatively high fields. Through a systematic variation of concentration and magnetic field strength, this study shows that both magnetic field strength and change in concentration can strongly influence formation of microstructures even in weak dipolar systems. Additionally, the results of two commonly used support films on electron microscopy grids, continuous carbon and holey carbon films, are compared. Holey carbon film allows us to create local regions of high concentrations that further assist the development of field-induced assemblies. The experimental observations provide a validation of the zippering effect and can be utilized in the development of models for thermophysical properties such as thermal conductivity. PMID:25829566

  8. Direct observations of field-induced assemblies in magnetite ferrofluids

    NASA Astrophysics Data System (ADS)

    Mousavi, N. S. Susan; Khapli, Sachin D.; Kumar, Sunil

    2015-03-01

    Evolution of microstructures in magnetite-based ferrofluids with weak dipolar moments (particle size ≤ 10 nm) is studied with an emphasis on examining the effects of particle concentration (ϕ) and magnetic field strength (H) on the structures. Nanoparticles are dispersed in water at three different concentrations, ϕ = 0.15%, 0.48%, and 0.59% (w/v) [g/ml%] and exposed to uniform magnetic fields in the range of H = 0.05-0.42 T. Cryogenic transmission electron microscopy is employed to provide in-situ observations of the field-induced assemblies in such systems. As the magnetic field increases, the Brownian colloids are observed to form randomly distributed chains aligned in the field direction, followed by head-to-tail chain aggregation and then lateral aggregation of chains termed as zippering. By increasing the field in low concentration samples, the number of chains increases, though their length does not change dramatically. Increasing concentration increases the length of the linear particle assemblies in the presence of a fixed external magnetic field. Thickening of the chains due to zippering is observed at relatively high fields. Through a systematic variation of concentration and magnetic field strength, this study shows that both magnetic field strength and change in concentration can strongly influence formation of microstructures even in weak dipolar systems. Additionally, the results of two commonly used support films on electron microscopy grids, continuous carbon and holey carbon films, are compared. Holey carbon film allows us to create local regions of high concentrations that further assist the development of field-induced assemblies. The experimental observations provide a validation of the zippering effect and can be utilized in the development of models for thermophysical properties such as thermal conductivity.

  9. Direct observations of field-induced assemblies in magnetite ferrofluids

    SciTech Connect

    Mousavi, N. S. Susan; Khapli, Sachin D.; Kumar, Sunil

    2015-03-14

    Evolution of microstructures in magnetite-based ferrofluids with weak dipolar moments (particle size ≤ 10 nm) is studied with an emphasis on examining the effects of particle concentration (ϕ) and magnetic field strength (H) on the structures. Nanoparticles are dispersed in water at three different concentrations, ϕ = 0.15%, 0.48%, and 0.59% (w/v) [g/ml%] and exposed to uniform magnetic fields in the range of H = 0.05–0.42 T. Cryogenic transmission electron microscopy is employed to provide in-situ observations of the field-induced assemblies in such systems. As the magnetic field increases, the Brownian colloids are observed to form randomly distributed chains aligned in the field direction, followed by head-to-tail chain aggregation and then lateral aggregation of chains termed as zippering. By increasing the field in low concentration samples, the number of chains increases, though their length does not change dramatically. Increasing concentration increases the length of the linear particle assemblies in the presence of a fixed external magnetic field. Thickening of the chains due to zippering is observed at relatively high fields. Through a systematic variation of concentration and magnetic field strength, this study shows that both magnetic field strength and change in concentration can strongly influence formation of microstructures even in weak dipolar systems. Additionally, the results of two commonly used support films on electron microscopy grids, continuous carbon and holey carbon films, are compared. Holey carbon film allows us to create local regions of high concentrations that further assist the development of field-induced assemblies. The experimental observations provide a validation of the zippering effect and can be utilized in the development of models for thermophysical properties such as thermal conductivity.

  10. Evaluation of Handheld Computers for Direct Systematic Classroom Observation

    ERIC Educational Resources Information Center

    Bahr, Michael W.; Gouwens, Donald A.; Schuh, Genevieve

    2012-01-01

    Through this study the authors evaluate outcomes associated with the use of handheld computers by interventionists in improving the efficiency of direct systematic classroom observation. Information from observations is used by interventionists for treatment planning and evaluation. In this study, interventionists were trained to use personal…

  11. Direct Observational Assessment during Test Sessions and Child Clinical Interviews

    ERIC Educational Resources Information Center

    McConaughy, Stephanie H.

    2005-01-01

    Test sessions and child clinical interviews offer opportunities for direct observations of children's behavior in controlled settings. Moreover, standardized instruments for test session and interview observations offer more reliable and valid assessment methods than do anecdotal reports. This article reviews characteristics and psychometric…

  12. Plasmon Surface Polariton Dispersion by Direct Optical Observation.

    ERIC Educational Resources Information Center

    Swalen, J. D.; And Others

    1980-01-01

    Describes several simple experiments that can be used to observe directly the dispersion curve of plasmon surface polaritons (PSP) on flat metal surfaces. A method is described of observing the increonental change in the wave vector of the PSP due to coatings that differ in thickness by a few nanometers. (Author/CS)

  13. Combined use of leaf size and economics traits allows direct comparison of hydrophyte and terrestrial herbaceous adaptive strategies

    PubMed Central

    Pierce, Simon; Brusa, Guido; Sartori, Matteo; Cerabolini, Bruno E. L.

    2012-01-01

    Background and Aims Hydrophytes generally exhibit highly acquisitive leaf economics. However, a range of growth forms is evident, from small, free-floating and rapidly growing Lemniden to large, broad-leaved Nymphaeiden, denoting variability in adaptive strategies. Traits used to classify adaptive strategies in terrestrial species, such as canopy height, are not applicable to hydrophytes. We hypothesize that hydrophyte leaf size traits and economics exhibit sufficient overlap with terrestrial species to allow a common classification of plant functional types, sensu Grime's CSR theory. Methods Leaf morpho-functional traits were measured for 61 species from 47 water bodies in lowland continental, sub-alpine and alpine bioclimatic zones in southern Europe and compared against the full leaf economics spectrum and leaf size range of terrestrial herbs, and between hydrophyte growth forms. Key Results Hydrophytes differed in the ranges and mean values of traits compared with herbs, but principal components analysis (PCA) demonstrated that both groups shared axes of trait variability: PCA1 encompassed size variation (area and mass), and PCA2 ranged from relatively dense, carbon-rich leaves to nitrogen-rich leaves of high specific leaf area (SLA). Most growth forms exhibited trait syndromes directly equivalent to herbs classified as R adapted, although Nymphaeiden ranged between C and SR adaptation. Conclusions Our findings support the hypothesis that hydrophyte adaptive strategy variation reflects fundamental trade-offs in economics and size that govern all plants, and that hydrophyte adaptive strategies can be directly compared with terrestrial species by combining leaf economics and size traits. PMID:22337079

  14. Retinex Image Processing: Improved Fidelity To Direct Visual Observation

    NASA Technical Reports Server (NTRS)

    Jobson, Daniel J.; Rahman, Zia-Ur; Woodell, Glenn A.

    1996-01-01

    Recorded color images differ from direct human viewing by the lack of dynamic range compression and color constancy. Research is summarized which develops the center/surround retinex concept originated by Edwin Land through a single scale design to a multi-scale design with color restoration (MSRCR). The MSRCR synthesizes dynamic range compression, color constancy, and color rendition and, thereby, approaches fidelity to direct observation.

  15. Modelling 1-minute directional observations of the global irradiance.

    NASA Astrophysics Data System (ADS)

    Thejll, Peter; Pagh Nielsen, Kristian; Andersen, Elsa; Furbo, Simon

    2016-04-01

    Direct and diffuse irradiances from the sky has been collected at 1-minute intervals for about a year from the experimental station at the Technical University of Denmark for the IEA project "Solar Resource Assessment and Forecasting". These data were gathered by pyrheliometers tracking the Sun, as well as with apertured pyranometers gathering 1/8th and 1/16th of the light from the sky in 45 degree azimuthal ranges pointed around the compass. The data are gathered in order to develop detailed models of the potentially available solar energy and its variations at high temporal resolution in order to gain a more detailed understanding of the solar resource. This is important for a better understanding of the sub-grid scale cloud variation that cannot be resolved with climate and weather models. It is also important for optimizing the operation of active solar energy systems such as photovoltaic plants and thermal solar collector arrays, and for passive solar energy and lighting to buildings. We present regression-based modelling of the observed data, and focus, here, on the statistical properties of the model fits. Using models based on the one hand on what is found in the literature and on physical expectations, and on the other hand on purely statistical models, we find solutions that can explain up to 90% of the variance in global radiation. The models leaning on physical insights include terms for the direct solar radiation, a term for the circum-solar radiation, a diffuse term and a term for the horizon brightening/darkening. The purely statistical model is found using data- and formula-validation approaches picking model expressions from a general catalogue of possible formulae. The method allows nesting of expressions, and the results found are dependent on and heavily constrained by the cross-validation carried out on statistically independent testing and training data-sets. Slightly better fits -- in terms of variance explained -- is found using the purely

  16. The Validity of Direct Observation Measures of Pupil Classroom Behavior.

    ERIC Educational Resources Information Center

    Hoge, Robert D.

    1985-01-01

    An evaluation of the validity of direct observation measures of pupil classroom behaviors is presented. Three types of measures are discussed: molar, molecular, and molecular-composite. Consistent support for the validity of molar and molecular-composite types of measures is revealed. (Author/LMO)

  17. New Directions: Emerging Satellite Observations of Above-cloud Aerosols and Direct Radiative Forcing

    NASA Technical Reports Server (NTRS)

    Yu, Hongbin; Zhang, Zhibo

    2013-01-01

    Spaceborne lidar and passive sensors with multi-wavelength and polarization capabilities onboard the A-Train provide unprecedented opportunities of observing above-cloud aerosols and direct radiative forcing. Significant progress has been made in recent years in exploring these new aerosol remote sensing capabilities and generating unique datasets. The emerging observations will advance the understanding of aerosol climate forcing.

  18. SPICA Coronagraph for the Direct Observation of Exo-Planets

    NASA Astrophysics Data System (ADS)

    Enya, K.; S. W. Group

    2011-12-01

    We present a mid-infrared coronagraph which targets the direct observation of exo-planets for the Space Infrared telescope for Cosmology and Astrophysics (SPICA). Study and experiment are ongoing for an coronagraph for SPICA, and this coronagraph is currently regarded as an option of the focal plane instruments. The primary target of the SPICA coronagraph is the direct imaging and spectroscopy of exo-planets in infrared. The SPICA mission gives us a unique opportunity for high-contrast observations, because of its large telescope aperture (3.5 m), the clean point-spread function provided by the monolithic telescope mirrors, and the capability for infrared observations from space. Laboratory experiments were performed with a visible laser to demonstrate the principles of the coronagraph. In an experiment using a binary-shaped pupil coronagraph, it was demonstrated that the contrast exceeded the requirement of SPICA, 10×10-6. A coronagraph obtained using a binary-shaped pupil mask is a baseline solution for SPICA because of its feasibility and robustness, while the use of a phase-induced amplitude apodization/binary-mask hybrid coronagraph is also considered as an option. Further developments are ongoing in order to realize a mid-infrared coronagraph for SPICA. Considering SPICA to be an essential platform for coronagraphic studies, and taking into account the progress of key technologies, we propose to develop a mid-infrared coronagraph instrument for SPICA and to perform the direct observation of exo-planets by using it.

  19. Direct Observations of the Evolution of Polar Cap Ionization Patches

    NASA Astrophysics Data System (ADS)

    Zhang, Q.; Zhang, B.; Lockwood, M. M.; Hu, H.; Moen, J. I.; Ruohoniemi, J.; Thomas, E. G.; Zhang, S.; Yang, H.; Liu, R.; McWilliams, K. A.; Baker, J. B.

    2013-12-01

    Patches of ionization are common in the polar ionosphere where their motion and associated density gradients give variable disturbances to High Frequency (HF) radio communications, over-the-horizon radar location errors, and disruption and errors to satellite navigation and communication. Their formation and evolution are poorly understood, particularly under disturbed space weather conditions. We report direct observations of the full evolution of patches during a geomagnetic storm, including formation, polar cap entry, transpolar evolution, polar cap exit, and sunward return flow. Our observations show that modulation of nightside reconnection in the substorm cycle of the magnetosphere helps form the gaps between patches where steady convection would give a 'tongue' of ionization (TOI).

  20. Microcrack closure in rocks under stress - Direct observation

    NASA Technical Reports Server (NTRS)

    Batzle, M. L.; Simmons, G.; Siegfried, R. W.

    1980-01-01

    Direct observations of the closure of microcracks in rocks under increasing stress are reported. Uniaxial stresses up to 300 bars were applied to untreated and previously heated samples of Westerly granite and Frederick diabase by a small hydraulic press which fit entirely within a scanning electron microscope. Crack closure characteristics are found to depend on crack orientation, with cracks perpendicular to the applied stress closing and those parallel tending to open, as well as crack aspect ratio, crack intersection properties, stress concentrations and surface roughness. Uniaxial and hydrostatic stress measurements are found to be strongly dependent on fracture content as observed by SEM, and the observed hysteresis in strain measurements in the first stress cycles is also related to microscopic processes

  1. Direct observation of intermolecular interactions mediated by hydrogen bonding

    NASA Astrophysics Data System (ADS)

    De Marco, Luigi; Thämer, Martin; Reppert, Mike; Tokmakoff, Andrei

    2014-07-01

    Although intermolecular interactions are ubiquitous in physicochemical phenomena, their dynamics have proven difficult to observe directly, and most experiments rely on indirect measurements. Using broadband two-dimensional infrared spectroscopy (2DIR), we have measured the influence of hydrogen bonding on the intermolecular vibrational coupling between dimerized N-methylacetamide molecules. In addition to strong intramolecular coupling between N-H and C=O oscillators, cross-peaks in the broadband 2DIR spectrum appearing upon dimerization reveal strong intermolecular coupling that changes the character of the vibrations. In addition, dimerization changes the effects of intramolecular coupling, resulting in Fermi resonances between high and low-frequency modes. These results illustrate how hydrogen bonding influences the interplay of inter- and intramolecular vibrations, giving rise to correlated nuclear motions and significant changes in the vibrational structure of the amide group. These observations have direct impact on modeling and interpreting the IR spectra of proteins. In addition, they illustrate a general approach to direct molecular characterization of intermolecular interactions.

  2. Direct observation of intermolecular interactions mediated by hydrogen bonding

    SciTech Connect

    De Marco, Luigi; Reppert, Mike; Thämer, Martin; Tokmakoff, Andrei

    2014-07-21

    Although intermolecular interactions are ubiquitous in physicochemical phenomena, their dynamics have proven difficult to observe directly, and most experiments rely on indirect measurements. Using broadband two-dimensional infrared spectroscopy (2DIR), we have measured the influence of hydrogen bonding on the intermolecular vibrational coupling between dimerized N-methylacetamide molecules. In addition to strong intramolecular coupling between N–H and C=O oscillators, cross-peaks in the broadband 2DIR spectrum appearing upon dimerization reveal strong intermolecular coupling that changes the character of the vibrations. In addition, dimerization changes the effects of intramolecular coupling, resulting in Fermi resonances between high and low-frequency modes. These results illustrate how hydrogen bonding influences the interplay of inter- and intramolecular vibrations, giving rise to correlated nuclear motions and significant changes in the vibrational structure of the amide group. These observations have direct impact on modeling and interpreting the IR spectra of proteins. In addition, they illustrate a general approach to direct molecular characterization of intermolecular interactions.

  3. Direct Observation of Luminescent Silver Clusters Confined in Faujasite Zeolites.

    PubMed

    Altantzis, Thomas; Coutino-Gonzalez, Eduardo; Baekelant, Wouter; Martinez, Gerardo T; Abakumov, Artem M; Tendeloo, Gustaaf Van; Roeffaers, Maarten B J; Bals, Sara; Hofkens, Johan

    2016-08-23

    One of the ultimate goals in the study of metal clusters is the correlation between the atomic-scale organization and their physicochemical properties. However, direct observation of the atomic organization of such minuscule metal clusters is heavily hindered by radiation damage imposed by the different characterization techniques. We present direct evidence of the structural arrangement, at an atomic level, of luminescent silver species stabilized in faujasite (FAU) zeolites using aberration-corrected scanning transmission electron microscopy. Two different silver clusters were identified in Ag-FAU zeolites, a trinuclear silver species associated with green emission and a tetranuclear silver species related to yellow emission. By combining direct imaging with complementary information obtained from X-ray powder diffraction and Rietveld analysis, we were able to elucidate the main differences at an atomic scale between luminescent (heat-treated) and nonluminescent (cation-exchanged) Ag-FAU zeolites. It is expected that such insights will trigger the directed synthesis of functional metal nanocluster-zeolite composites with tailored luminescent properties. PMID:27391548

  4. Direct observation of lubricant additives using tomography techniques

    NASA Astrophysics Data System (ADS)

    Chen, Yunyun; Sanchez, Carlos; Parkinson, Dilworth Y.; Liang, Hong

    2016-07-01

    Lubricants play important roles in daily activities such as driving, walking, and cooking. The current understanding of mechanisms of lubrication, particularly in mechanical systems, has been limited by the lack of capability in direct observation. Here, we report an in situ approach to directly observe the motion of additive particles in grease under the influence of shear. Using the K-edge tomography technique, it is possible to detect particular additives in a grease and observe their distribution through 3D visualization. A commercial grease as a reference was studied with and without an inorganic additive of Fe3O4 microparticles. The results showed that it was possible to identify these particles and track their movement. Under a shear stress, Fe3O4 particles were found to adhere to the edge of calcium complex thickeners commonly used in grease. Due to sliding, the grease formed a film with increased density. This approach enables in-line monitoring of a lubricant and future investigation in mechanisms of lubrication.

  5. Direct state reconstruction with coupling-deformed pointer observables

    NASA Astrophysics Data System (ADS)

    Zhu, Xuanmin; Zhang, Yu-Xiang; Wu, Shengjun

    2016-06-01

    Direct state tomography (DST) using weak measurements has received wide attention. Based on the concept of coupling-deformed pointer observables presented by Zhang et al. [Y.-X. Zhang, S. Wu, and Z.-B. Chen, Phys. Rev. A 93, 032128 (2016), 10.1103/PhysRevA.93.032128], a modified direct state tomography (MDST) is proposed, examined, and compared with other typical state tomography schemes. MDST has exact validity for measurements of any strength. We identify the strength needed to attain the highest efficiency level of MDST by using statistical theory. MDST is much more efficient than DST in the sense that far fewer samples are needed to reach DST's level of reconstruction accuracy. Moreover, MDST has no inherent bias when compared to DST.

  6. Direct observation of negative-index microwave surface waves.

    PubMed

    Dockrey, J A; Horsley, S A R; Hooper, I R; Sambles, J R; Hibbins, A P

    2016-01-01

    Waves propagating in a negative-index material have wave-front propagation (wavevector, k) opposite in direction to that of energy flow (Poynting vector, S). Here we present an experimental realisation at microwave frequencies of an analogous surface wave phenomenon whereby a metasurface supports a surface mode that has two possible wavevector eigenstates within a narrow band of frequencies: one that supports surface waves with positive mode index, and another that supports surface waves with negative mode index. Phase sensitive measurements of the near-field of surface waves across the metasurface show the contrasting spatial evolution of the two eigenstates, providing a unique opportunity to directly observe the negative-index phenomenon. PMID:26903284

  7. Direct observation of negative-index microwave surface waves

    NASA Astrophysics Data System (ADS)

    Dockrey, J. A.; Horsley, S. A. R.; Hooper, I. R.; Sambles, J. R.; Hibbins, A. P.

    2016-02-01

    Waves propagating in a negative-index material have wave-front propagation (wavevector, k) opposite in direction to that of energy flow (Poynting vector, S). Here we present an experimental realisation at microwave frequencies of an analogous surface wave phenomenon whereby a metasurface supports a surface mode that has two possible wavevector eigenstates within a narrow band of frequencies: one that supports surface waves with positive mode index, and another that supports surface waves with negative mode index. Phase sensitive measurements of the near-field of surface waves across the metasurface show the contrasting spatial evolution of the two eigenstates, providing a unique opportunity to directly observe the negative-index phenomenon.

  8. Direct observation of negative-index microwave surface waves

    PubMed Central

    Dockrey, J. A.; Horsley, S. A. R.; Hooper, I. R.; Sambles, J. R.; Hibbins, A. P.

    2016-01-01

    Waves propagating in a negative-index material have wave-front propagation (wavevector, k) opposite in direction to that of energy flow (Poynting vector, S). Here we present an experimental realisation at microwave frequencies of an analogous surface wave phenomenon whereby a metasurface supports a surface mode that has two possible wavevector eigenstates within a narrow band of frequencies: one that supports surface waves with positive mode index, and another that supports surface waves with negative mode index. Phase sensitive measurements of the near-field of surface waves across the metasurface show the contrasting spatial evolution of the two eigenstates, providing a unique opportunity to directly observe the negative-index phenomenon. PMID:26903284

  9. Direct observation of closure domain wall mediated spin waves

    SciTech Connect

    Mozooni, Babak McCord, Jeffrey

    2015-07-27

    The generation and guiding of spin waves from and by magnetic domain walls are demonstrated. The spin waves radiate from pinned and oscillating magnetic closure domain walls and propagate linearly along a narrow path formed by the surrounding 180° asymmetric Bloch domain walls. The propagating spin wave modes are directly visualized by time-resolved magneto-optical Kerr microscopy with picosecond temporal resolution. A linear relationship between excitation frequency, wavelength, and number of spin waves per domain exists. Independent of the field excitation frequency, a constant phase velocity of spin waves propagation is obtained. Spin waves characteristics can be tuned by varying the magnetic domain dynamics, allowing for variable spin wave characteristics with magnetic field characteristics and histories.

  10. Direct Observation of Teacher and Student Behavior in School Settings: Trends, Issues and Future Directions

    ERIC Educational Resources Information Center

    Lewis, Timothy J.; Scott, Terrance M.; Wehby, Joseph H.; Wills, Howard P.

    2014-01-01

    Across the modern history of the field of special education and emotional/behavioral disorders (EBD), direct observation of student and educator behavior has been an essential component of the diagnostic process, student progress monitoring, and establishing functional and statistical relationships within research. This article provides an…

  11. Direct Observation of Correlated Interdomain Motion in Alcohol Dehydrogenase

    SciTech Connect

    Biehl, Ralf; Monkenbusch, Michael; Richter, Dieter; Hoffmann, Bernd; Merkel, Rudolf; Falus, Peter; Preost, Sylvain

    2008-09-26

    Interdomain motions in proteins are essential to enable or promote biochemical function. Neutron spin-echo spectroscopy is used to directly observe the domain dynamics of the protein alcohol dehydrogenase. The collective motion of domains as revealed by their coherent form factor relates to the cleft opening dynamics between the binding and the catalytic domains enabling binding and release of the functional important cofactor. The cleft opening mode hardens as a result of an overall stiffening of the domain complex due to the binding of the cofactor.

  12. Direct observation of Kelvin waves excited by quantized vortex reconnection.

    PubMed

    Fonda, Enrico; Meichle, David P; Ouellette, Nicholas T; Hormoz, Sahand; Lathrop, Daniel P

    2014-03-25

    Quantized vortices are key features of quantum fluids such as superfluid helium and Bose-Einstein condensates. The reconnection of quantized vortices and subsequent emission of Kelvin waves along the vortices are thought to be central to dissipation in such systems. By visualizing the motion of submicron particles dispersed in superfluid (4)He, we have directly observed the emission of Kelvin waves from quantized vortex reconnection. We characterize one event in detail, using dimensionless similarity coordinates, and compare it with several theories. Finally, we give evidence for other examples of wavelike behavior in our system. PMID:24704878

  13. Direct observation of Kelvin waves excited by quantized vortex reconnection

    PubMed Central

    Fonda, Enrico; Meichle, David P.; Ouellette, Nicholas T.; Hormoz, Sahand; Lathrop, Daniel P.

    2014-01-01

    Quantized vortices are key features of quantum fluids such as superfluid helium and Bose–Einstein condensates. The reconnection of quantized vortices and subsequent emission of Kelvin waves along the vortices are thought to be central to dissipation in such systems. By visualizing the motion of submicron particles dispersed in superfluid 4He, we have directly observed the emission of Kelvin waves from quantized vortex reconnection. We characterize one event in detail, using dimensionless similarity coordinates, and compare it with several theories. Finally, we give evidence for other examples of wavelike behavior in our system. PMID:24704878

  14. Direct observation of small cluster mobility and ripening

    NASA Technical Reports Server (NTRS)

    Heinemann, K.; Poppa, H.

    1976-01-01

    Direct evidence is reported for the simultaneous occurrence of Ostwald ripening and short-distance cluster mobility during annealing of discontinuous metal films on clean amorphous substrates. The annealing characteristics of very thin particulate deposits of silver on amorphized clean surfaces of single-crystalline thin graphite substrates have been studied by in situ transmission electron microscopy (TEM) under controlled environmental conditions in the temperature range from 25 to 450 C. It was possible to monitor all stages of the experiments by TEM observation of the same specimen area. Slow Ostwald ripening was found to occur over the entire temperature range, but the overriding surface transport mechanism was short-distance cluster mobility. This was concluded from in situ observations of individual particles during annealing and from measurements of cluster size distributions, cluster number densities, area coverages, and mean cluster diameters.

  15. Direct observations of the evolution of polar cap ionization patches.

    PubMed

    Zhang, Qing-He; Zhang, Bei-Chen; Lockwood, Michael; Hu, Hong-Qiao; Moen, Jøran; Ruohoniemi, J Michael; Thomas, Evan G; Zhang, Shun-Rong; Yang, Hui-Gen; Liu, Rui-Yuan; McWilliams, Kathryn A; Baker, Joseph B H

    2013-03-29

    Patches of ionization are common in the polar ionosphere, where their motion and associated density gradients give variable disturbances to high-frequency (HF) radio communications, over-the-horizon radar location errors, and disruption and errors to satellite navigation and communication. Their formation and evolution are poorly understood, particularly under disturbed space weather conditions. We report direct observations of the full evolution of patches during a geomagnetic storm, including formation, polar cap entry, transpolar evolution, polar cap exit, and sunward return flow. Our observations show that modulation of nightside reconnection in the substorm cycle of the magnetosphere helps form the gaps between patches where steady convection would give a "tongue" of ionization (TOI). PMID:23539601

  16. Direct observation of thitherto unobservable quantum phenomena by using electrons

    PubMed Central

    Tonomura, Akira

    2005-01-01

    Fundamental aspects of quantum mechanics, which were discussed only theoretically as “thought experiments” in the 1920s and 1930s, have begun to frequently show up in nanoscopic regions owing to recent rapid progress in advanced technologies. Quantum phenomena were once regarded as the ultimate factors limiting further miniaturization trends of microstructured electronic devices, but now they have begun to be actively used as the principles for new devices such as quantum computers. To directly observe what had been unobservable quantum phenomena, we have tried to develop bright and monochromatic electron beams for the last 35 years. Every time the brightness of an electron beam improved, fundamental experiments in quantum mechanics became possible, and quantum phenomena became observable by using the wave nature of electrons. PMID:16150719

  17. Directly observable optical properties of sprites in Central Europe

    NASA Astrophysics Data System (ADS)

    Bór, József

    2013-04-01

    Luminous optical emissions accompanying streamer-based natural electric breakdown processes initiating in the mesosphere are called sprites. 489 sprite events have been observed with a TV frame rate video system in Central Europe from Sopron (47.68N, 16.58E, 230 m MSL), Hungary between 2007 and 2009. On the basis of these observations, characteristic morphological properties of sprites, i.e. basic forms (e.g. column, carrot, angel, etc.) as well as common morphological features (e.g. tendrils, glows, puffs, beads, etc.), have been identified. Probable time sequences of streamer propagation directions were associated with each of the basic sprite forms. It is speculated that different sequences of streamer propagation directions can result in very similar final sprite shapes. The number and type variety of sprite elements appearing in an event as well as the total optical duration of an event was analyzed statistically. Jellyfish and dancing sprite events were considered as special subsets of sprite clusters. It was found that more than 90% of the recorded sprite elements appeared in clusters rather than alone and more than half of the clusters contained more than one basic sprite forms. The analysis showed that jellyfish sprites and clusters of column sprites featuring glows and tendrils do not tend to have optical lifetimes longer than 80 ms. Such very long optical lifetimes have not been observed in sprite clusters containing more than 25 elements of any type, either. In contrast to clusters containing sprite entities of only one form, sprite events showing more sprite forms seem to have extended optical durations more likely. The need for further investigation and for finding theoretical concepts to link these observations to electric conditions ambient for sprite formation is emphasized.

  18. Direct observation of photoinduced bent nitrosyl excited-state complexes

    SciTech Connect

    Sawyer, Karma R.; Steele, Ryan P.; Glascoe, Elizabeth A.; Cahoon, James F.; Schlegel, Jacob P.; Head-Gordon, Martin; Harris, Charles B.

    2008-06-28

    Ground state structures with side-on nitrosyl ({eta}{sup 2}-NO) and isonitrosyl (ON) ligands have been observed in a variety of transition-metal complexes. In contrast, excited state structures with bent-NO ligands have been proposed for years but never directly observed. Here we use picosecond time-resolved infrared spectroscopy and density functional theory (DFT) modeling to study the photochemistry of Co(CO){sub 3}(NO), a model transition-metal-NO compound. Surprisingly, we have observed no evidence for ON and {eta}{sup 2}-NO structural isomers, but have observed two bent-NO complexes. DFT modeling of the ground and excited state potentials indicates that the bent-NO complexes correspond to triplet excited states. Photolysis of Co(CO){sub 3}(NO) with a 400-nm pump pulse leads to population of a manifold of excited states which decay to form an excited state triplet bent-NO complex within 1 ps. This structure relaxes to the ground triplet state in ca. 350 ps to form a second bent-NO structure.

  19. Direct Observation Assessment of Milestones: Problems with Reliability

    PubMed Central

    Schott, Meghan; Kedia, Raashee; Promes, Susan B.; Swoboda, Thomas; O’Rourke, Kevin; Green, Walter; Liu, Rachel; Stansfield, Brent; Santen, Sally A.

    2015-01-01

    Introduction Emergency medicine (EM) milestones are used to assess residents’ progress. While some milestone validity evidence exists, there is a lack of standardized tools available to reliably assess residents. Inherent to this is a concern that we may not be truly measuring what we intend to assess. The purpose of this study was to design a direct observation milestone assessment instrument supported by validity and reliability evidence. In addition, such a tool would further lend validity evidence to the EM milestones by demonstrating their accurate measurement. Methods This was a multi-center, prospective, observational validity study conducted at eight institutions. The Critical Care Direct Observation Tool (CDOT) was created to assess EM residents during resuscitations. This tool was designed using a modified Delphi method focused on content, response process, and internal structure validity. Paying special attention to content validity, the CDOT was developed by an expert panel, maintaining the use of the EM milestone wording. We built response process and internal consistency by piloting and revising the instrument. Raters were faculty who routinely assess residents on the milestones. A brief training video on utilization of the instrument was completed by all. Raters used the CDOT to assess simulated videos of three residents at different stages of training in a critical care scenario. We measured reliability using Fleiss’ kappa and interclass correlations. Results Two versions of the CDOT were used: one used the milestone levels as global rating scales with anchors, and the second reflected a current trend of a checklist response system. Although the raters who used the CDOT routinely rate residents in their practice, they did not score the residents’ performances in the videos comparably, which led to poor reliability. The Fleiss’ kappa of each of the items measured on both versions of the CDOT was near zero. Conclusion The validity and

  20. Direct observation of the strange b baryon Xib-.

    PubMed

    Abazov, V M; Abbott, B; Abolins, M; Acharya, B S; Adams, M; Adams, T; Aguilo, E; Ahn, S H; Ahsan, M; Alexeev, G D; Alkhazov, G; Alton, A; Alverson, G; Alves, G A; Anastasoaie, M; Ancu, L S; Andeen, T; Anderson, S; Andrieu, B; Anzelc, M S; Arnoud, Y; Arov, M; Arthaud, M; Askew, A; Asman, B; Assis Jesus, A C S; Atramentov, O; Autermann, C; Avila, C; Ay, C; Badaud, F; Baden, A; Bagby, L; Baldin, B; Bandurin, D V; Banerjee, S; Banerjee, P; Barberis, E; Barfuss, A-F; Bargassa, P; Baringer, P; Barreto, J; Bartlett, J F; Bassler, U; Bauer, D; Beale, S; Bean, A; Begalli, M; Begel, M; Belanger-Champagne, C; Bellantoni, L; Bellavance, A; Benitez, J A; Beri, S B; Bernardi, G; Bernhard, R; Berntzon, L; Bertram, I; Besançon, M; Beuselinck, R; Bezzubov, V A; Bhat, P C; Bhatnagar, V; Biscarat, C; Blazey, G; Blekman, F; Blessing, S; Bloch, D; Bloom, K; Boehnlein, A; Boline, D; Bolton, T A; Borissov, G; Bos, K; Bose, T; Brandt, A; Brock, R; Brooijmans, G; Bross, A; Brown, D; Buchanan, N J; Buchholz, D; Buehler, M; Buescher, V; Burdin, S; Burke, S; Burnett, T H; Buszello, C P; Butler, J M; Calfayan, P; Calvet, S; Cammin, J; Caron, S; Carvalho, W; Casey, B C K; Cason, N M; Castilla-Valdez, H; Chakrabarti, S; Chakraborty, D; Chan, K M; Chan, K; Chandra, A; Charles, F; Cheu, E; Chevallier, F; Cho, D K; Choi, S; Choudhary, B; Christofek, L; Christoudias, T; Cihangir, S; Claes, D; Clément, C; Clément, B; Coadou, Y; Cooke, M; Cooper, W E; Corcoran, M; Couderc, F; Cousinou, M-C; Crépé-Renaudin, S; Cutts, D; Cwiok, M; da Motta, H; Das, A; Davies, G; De, K; de Jong, S J; de Jong, P; De La Cruz-Burelo, E; De Oliveira Martins, C; Degenhardt, J D; Déliot, F; Demarteau, M; Demina, R; Denisov, D; Denisov, S P; Desai, S; Diehl, H T; Diesburg, M; Dominguez, A; Dong, H; Dudko, L V; Duflot, L; Dugad, S R; Duggan, D; Duperrin, A; Dyer, J; Dyshkant, A; Eads, M; Edmunds, D; Ellison, J; Elvira, V D; Enari, Y; Eno, S; Ermolov, P; Evans, H; Evdokimov, A; Evdokimov, V N; Ferapontov, A V; Ferbel, T; Fiedler, F; Filthaut, F; Fisher, W; Fisk, H E; Ford, M; Fortner, M; Fox, H; Fu, S; Fuess, S; Gadfort, T; Galea, C F; Gallas, E; Galyaev, E; Garcia, C; Garcia-Bellido, A; Gavrilov, V; Gay, P; Geist, W; Gelé, D; Gerber, C E; Gershtein, Y; Gillberg, D; Ginther, G; Gollub, N; Gómez, B; Goussiou, A; Grannis, P D; Greenlee, H; Greenwood, Z D; Gregores, E M; Grenier, G; Gris, Ph; Grivaz, J-F; Grohsjean, A; Grünendahl, S; Grünewald, M W; Guo, J; Guo, F; Gutierrez, P; Gutierrez, G; Haas, A; Hadley, N J; Haefner, P; Hagopian, S; Haley, J; Hall, I; Hall, R E; Han, L; Hanagaki, K; Hansson, P; Harder, K; Harel, A; Harrington, R; Hauptman, J M; Hauser, R; Hays, J; Hebbeker, T; Hedin, D; Hegeman, J G; Heinmiller, J M; Heinson, A P; Heintz, U; Hensel, C; Herner, K; Hesketh, G; Hildreth, M D; Hirosky, R; Hobbs, J D; Hoeneisen, B; Hoeth, H; Hohlfeld, M; Hong, S J; Hooper, R; Hossain, S; Houben, P; Hu, Y; Hubacek, Z; Hynek, V; Iashvili, I; Illingworth, R; Ito, A S; Jabeen, S; Jaffré, M; Jain, S; Jakobs, K; Jarvis, C; Jesik, R; Johns, K; Johnson, C; Johnson, M; Jonckheere, A; Jonsson, P; Juste, A; Käfer, D; Kahn, S; Kajfasz, E; Kalinin, A M; Kalk, J R; Kalk, J M; Kappler, S; Karmanov, D; Kasper, J; Kasper, P; Katsanos, I; Kau, D; Kaur, R; Kaushik, V; Kehoe, R; Kermiche, S; Khalatyan, N; Khanov, A; Kharchilava, A; Kharzheev, Y M; Khatidze, D; Kim, H; Kim, T J; Kirby, M H; Kirsch, M; Klima, B; Kohli, J M; Konrath, J-P; Kopal, M; Korablev, V M; Kothari, B; Kozelov, A V; Krop, D; Kryemadhi, A; Kuhl, T; Kumar, A; Kunori, S; Kupco, A; Kurca, T; Kvita, J; Lacroix, F; Lam, D; Lammers, S; Landsberg, G; Lazoflores, J; Lebrun, P; Lee, W M; Leflat, A; Lehner, F; Lellouch, J; Lesne, V; Leveque, J; Lewis, P; Li, J; Li, Q Z; Li, L; Lietti, S M; Lima, J G R; Lincoln, D; Linnemann, J; Lipaev, V V; Lipton, R; Liu, Y; Liu, Z; Lobo, L; Lobodenko, A; Lokajicek, M; Lounis, A; Love, P; Lubatti, H J; Lyon, A L; Maciel, A K A; Mackin, D; Madaras, R J; Mättig, P; Magass, C; Magerkurth, A; Makovec, N; Mal, P K; Malbouisson, H B; Malik, S; Malyshev, V L; Mao, H S; Maravin, Y; Martin, B; McCarthy, R; Melnitchouk, A; Mendes, A; Mendoza, L; Mercadante, P G; Merekov, Y P; Merkin, M; Merritt, K W; Meyer, J; Meyer, A; Michaut, M; Millet, T; Mitrevski, J; Molina, J; Mommsen, R K; Mondal, N K; Moore, R W; Moulik, T; Muanza, G S; Mulders, M; Mulhearn, M; Mundal, O; Mundim, L; Nagy, E; Naimuddin, M; Narain, M; Naumann, N A; Neal, H A; Negret, J P; Neustroev, P; Nilsen, H; Nomerotski, A; Novaes, S F; Nunnemann, T; O'Dell, V; O'Neil, D C; Obrant, G; Ochando, C; Onoprienko, D; Oshima, N; Osta, J; Otec, R; Otero y Garzón, G J; Owen, M; Padley, P; Pangilinan, M; Panov, G; Parashar, N; Park, S-J; Park, S K; Parsons, J; Partridge, R; Parua, N; Patwa, A; Pawloski, G; Penning, B; Perea, P M; Peters, K; Peters, Y; Pétroff, P; Petteni, M; Piegaia, R; Piper, J; Pleier, M-A; Podesta-Lerma, P L M; Podstavkov, V M; Pogorelov, Y; Pol, M-E; Polozov, P; Pompos, A; Pope, B G; Popov, A V; Potter, C; Prado da Silva, W L; Prosper, H B; Protopopescu, S; Qian, J; Quadt, A; Quinn, B; Rakitine, A; Rangel, M S; Rani, K J; Ranjan, K; Ratoff, P N; Renkel, P; Reucroft, S; Rich, P; Rijssenbeek, M; Ripp-Baudot, I; Rizatdinova, F; Robinson, S; Rodrigues, R F; Royon, C; Rozhdestvenski, A; Rubinov, P; Ruchti, R; Safronov, G; Sajot, G; Sánchez-Hernández, A; Sanders, M P; Santoro, A; Savage, G; Sawyer, L; Scanlon, T; Schaile, D; Schamberger, R D; Scheglov, Y; Schellman, H; Schieferdecker, P; Schliephake, T; Schmitt, C; Schwanenberger, C; Schwartzman, A; Schwienhorst, R; Sekaric, J; Sengupta, S; Severini, H; Shabalina, E; Shamim, M; Shary, V; Shchukin, A A; Shivpuri, R K; Shpakov, D; Siccardi, V; Simak, V; Sirotenko, V; Skubic, P; Slattery, P; Smirnov, D; Smith, R P; Snow, J; Snow, G R; Snyder, S; Söldner-Rembold, S; Sonnenschein, L; Sopczak, A; Sosebee, M; Soustruznik, K; Souza, M; Spurlock, B; Stark, J; Steele, J; Stolin, V; Stone, A; Stoyanova, D A; Strandberg, J; Strandberg, S; Strang, M A; Strauss, M; Strauss, E; Ströhmer, R; Strom, D; Strovink, M; Stutte, L; Sumowidagdo, S; Svoisky, P; Sznajder, A; Talby, M; Tamburello, P; Tanasijczuk, A; Taylor, W; Telford, P; Temple, J; Tiller, B; Tissandier, F; Titov, M; Tokmenin, V V; Tomoto, M; Toole, T; Torchiani, I; Trefzger, T; Tsybychev, D; Tuchming, B; Tully, C; Tuts, P M; Unalan, R; Uvarov, S; Uvarov, L; Uzunyan, S; Vachon, B; van den Berg, P J; van Eijk, B; Van Kooten, R; van Leeuwen, W M; Varelas, N; Varnes, E W; Vartapetian, A; Vasilyev, I A; Vaupel, M; Verdier, P; Vertogradov, L S; Vertogradova, Y; Verzocchi, M; Villeneuve-Seguier, F; Vint, P; Vokac, P; Von Toerne, E; Voutilainen, M; Vreeswijk, M; Wagner, R; Wahl, H D; Wang, L; Wang, M H L S; Warchol, J; Watts, G; Wayne, M; Weber, M; Weber, G; Weerts, H; Wenger, A; Wermes, N; Wetstein, M; White, A; Wicke, D; Wilson, G W; Wimpenny, S J; Wobisch, M; Wood, D R; Wyatt, T R; Xie, Y; Yacoob, S; Yamada, R; Yan, M; Yasuda, T; Yatsunenko, Y A; Yip, K; Yoo, H D; Youn, S W; Yu, J; Yu, C; Yurkewicz, A; Zatserklyaniy, A; Zeitnitz, C; Zhang, D; Zhao, T; Zhou, B; Zhu, J; Zielinski, M; Zieminska, D; Zieminski, A; Zivkovic, L; Zutshi, V; Zverev, E G

    2007-08-01

    We report the first direct observation of the strange b baryon Xi(b)- (Xi(b)+). We reconstruct the decay Xi(b)- -->J/psiXi-, with J/psi-->mu+mu-, and Xi--->Lambdapi--->ppi-pi- in pp collisions at square root of s =1.96 TeV. Using 1.3 fb(-1) of data collected by the D0 detector, we observe 15.2 +/- 4.4(stat)(-0.4)(+1.9)(syst) Xi(b)- candidates at a mass of 5.774 +/- 0.011(stat) +/- 0.015(syst) GeV. The significance of the observed signal is 5.5 sigma, equivalent to a probability of 3.3 x 10(-8) of it arising from a background fluctuation. Normalizing to the decay Lambda(b)-->J/psiLambda, we measure the relative rate sigma(Xi(b-) x B(Xi)b})- -->J/psiXi-)/sigma(Lambda(b)) x B(Lambda(b)-->J/psiLambda) = 0.28+/-0.09(stat)(-0.08)(+0.09)(syst). PMID:17930744

  1. Direct and Semi-direct Radiative Responses to Observation-Constrained Aerosol Absorption over S Asia

    NASA Astrophysics Data System (ADS)

    Feng, Y.; Kotamarthi, V. R.; Manoharan, V.

    2013-12-01

    Climate impacts of aerosols over S. Asia have been studied extensively in both models and observations. However, discrepancies between observed and modeled aerosol concentrations and optical properties have hindered our understanding of the aerosol influences on the regional monsoon circulation and rainfall. We present an in-depth examination of direct and semi-direct radiative responses due to aerosols on the latitudinal heating gradient and cloud distribution, with observational constraints on solar absorption by aerosols. Regional distributions of aerosol concentration are simulated with a 12-km regional climate model (WRF-Chem) driven by the NCEP analysis data from August 2011 to March 2012. During this time period, the ground-based measurements of aerosols and clouds, surface radiation, water vapor, and temperature were taken at Nainital (29.38°N, 79.45°E) during the DOE Ganges Valley Experiment (GVAX). This data set, which is available at high temporal resolution (hourly), is used to evaluate and constrain the simulated wavelength dependence of aerosol absorption and the correlation with changes in surface radiation, cloud base height and liquid water content for the entire post-monsoon period. The analysis is extended to a regional scale by comparing with satellite observation of absorbing aerosol optical depth (OMI) and cloud properties (MODIS). Preliminary results show good agreement in monthly variations of simulated and observed aerosol optical depth (AOD) except during periods of high observed AOD. Initial analysis indicates a possible local origin for the aerosols that is not captured in the model at present. Furthermore, analysis of the spectrally resolved aerosol absorption measurements indicates that these local aerosols exhibit strong absorption in near-UV and visible wavelengths. A large fraction of increased absorption during October and November (local fall harvest season) is attributable to the super-micron sized aerosol particles. In

  2. Responses to the advanced notice of proposed rulemaking EPA published on June 6, 1996 regarding changes to the EPA allowance auctions and elimination of the direct sale

    SciTech Connect

    Critchfield, L.R.

    1997-12-31

    On June 6, 1996, EPA`s Acid Rain Program published an advance notice of proposed rulemaking (ANPRM) in the Federal Register seeking comment on: (1) whether to change the design of the annual sulfur dioxide (SO{sub 2}) allowance auctions; (2) whether to change the timing of the allowance auctions; (3) whether to change the requirement that the minimum price of offered allowances must be in whole dollars, and (4) whether EPA should propose the ability to submit allowance transfers electronically. EPA also published on that day a proposed and direct final rule on whether to eliminate the direct sale. This paper documents the issues addressed in the ANPRM, the comments EPA received, and EPA`s responses to those comments. EPA received comments from 14 separate commenters.

  3. Direct Observation of Smectic Layers in Thermotropic Liquid Crystals

    NASA Astrophysics Data System (ADS)

    Zhang, C.; Gao, M.; Diorio, N.; Weissflog, W.; Baumeister, U.; Sprunt, S.; Gleeson, J. T.; Jákli, A.

    2012-09-01

    We demonstrate subnanometer resolution cryo-TEM imaging of smectic layers in the smectic and nematic phases of two bent-core liquid crystals. Our results show perfect periodicity over several hundred layers in the smectic phase and also provide the first direct evidence of smectic clusters on length scales of 30-50 nm in a nematic liquid crystal. The results are corroborated with small angle x-ray scattering measurements. The observation of smectic clusters in the nematic phase is of special interest in bent-core liquid crystals, where the smectic clusters are stable over wide temperature ranges, in contrast to the well-known pretransitional “cybotactic” clusters that appear only in the vicinity of a bulk smectic phase. The means to characterize and manipulate this nanoscale molecular order could open up completely new liquid crystal-based technologies.

  4. A novel Gateway®-compatible binary vector allows direct selection of recombinant clones in Agrobacterium tumefaciens

    PubMed Central

    2011-01-01

    Background Cloning genes into plasmid vectors is one of the key steps for studying gene function. Recently, Invitrogen™ developed a convenient Gateway® cloning system based on the site-specific DNA recombination properties of bacteriophage lambda and the cytotoxic protein ccdB, which is lethal to most E. coli strains. The ccdB protein, however, is not toxic to Agrobacterium tumefaciens, an important player often used for studying gene function in planta. This limits the direct application of the Gateway® cloning system in plant transformation-mediated research. Results In this study, we constructed a novel Gateway®-compatible destination vector, pEG101-SacB/R, by replacing the ccdB gene with a SacB-SacR gene cassette as the negative selectable marker. Conclusion Our results demonstrate that the new pEG101-SacB/R destination vector can be used for Gateway® cloning in Agrobacterium tumefaciens. pEG101-SacB/R will be a valuable tool for high-throughput functional analysis of genes in planta. PMID:22145613

  5. Enabling direct nanoscale observations of biological reactions with dynamic TEM

    PubMed Central

    Evans, James E.; Browning, Nigel D.

    2013-01-01

    Biological processes occur on a wide range of spatial and temporal scales: from femtoseconds to hours and from angstroms to meters. Many new biological insights can be expected from a better understanding of the processes that occur on these very fast and very small scales. In this regard, new instruments that use fast X-ray or electron pulses are expected to reveal novel mechanistic details for macromolecular protein dynamics. To ensure that any observed conformational change is physiologically relevant and not constrained by 3D crystal packing, it would be preferable for experiments to utilize small protein samples such as single particles or 2D crystals that mimic the target protein's native environment. These samples are not typically amenable to X-ray analysis, but transmission electron microscopy has imaged such sample geometries for over 40 years using both direct imaging and diffraction modes. While conventional transmission electron microscopes (TEM) have visualized biological samples with atomic resolution in an arrested or frozen state, the recent development of the dynamic TEM (DTEM) extends electron microscopy into a dynamic regime using pump-probe imaging. A new second-generation DTEM, which is currently being constructed, has the potential to observe live biological processes with unprecedented spatiotemporal resolution by using pulsed electron packets to probe the sample on micro- and nanosecond timescales. This article reviews the experimental parameters necessary for coupling DTEM with in situ liquid microscopy to enable direct imaging of protein conformational dynamics in a fully hydrated environment and visualize reactions propagating in real time. PMID:23315566

  6. Direct observation of electron dynamics in the attosecond domain.

    PubMed

    Föhlisch, A; Feulner, P; Hennies, F; Fink, A; Menzel, D; Sanchez-Portal, D; Echenique, P M; Wurth, W

    2005-07-21

    Dynamical processes are commonly investigated using laser pump-probe experiments, with a pump pulse exciting the system of interest and a second probe pulse tracking its temporal evolution as a function of the delay between the pulses. Because the time resolution attainable in such experiments depends on the temporal definition of the laser pulses, pulse compression to 200 attoseconds (1 as = 10(-18) s) is a promising recent development. These ultrafast pulses have been fully characterized, and used to directly measure light waves and electronic relaxation in free atoms. But attosecond pulses can only be realized in the extreme ultraviolet and X-ray regime; in contrast, the optical laser pulses typically used for experiments on complex systems last several femtoseconds (1 fs = 10(-15) s). Here we monitor the dynamics of ultrafast electron transfer--a process important in photo- and electrochemistry and used in solid-state solar cells, molecular electronics and single-electron devices--on attosecond timescales using core-hole spectroscopy. We push the method, which uses the lifetime of a core electron hole as an internal reference clock for following dynamic processes, into the attosecond regime by focusing on short-lived holes with initial and final states in the same electronic shell. This allows us to show that electron transfer from an adsorbed sulphur atom to a ruthenium surface proceeds in about 320 as. PMID:16034414

  7. Direct observation of a sand-propped hydraulic fracture

    SciTech Connect

    Warpinski, N.R.; Tyler, L.D.; Vollendorf, W.C.; Northrop, D.A.

    1981-05-01

    An experiement has been conducted in which a sand-propped hydraulic fracture is created and then mined back to observe fracture behavior and proppant distribution. Three stages of different colored, different concentration sand transported by a water-based gel were injected into a volcanic ash fall tuff formation at a depth of 1400 ft near an existing tunnel complex. The resultant fracture was subsequently mined back for direct observation and photographed and mapped. This particular region was highly faulted and exhibited significant changes in in situ stress magnitudes across the faults; it is felt that this stress distribution resulted in very complex fracture behavior and growth processes. The fracture was bounded on one wing by a fault which was only a few feet from the wellbore. The fracture terminated on top at an unbonded bedding plane. Most of the injected volume of sand and fluid was forced downward, considerably below the elevation where the fracture was initiated. The different colors of sand were randomly distributed, although they were usually found in distinct layers, but this may have been due to the complex growth process. At different locations the fracture was found to have considerable variations in width; from several sand grains wide (1 cm) to devoid of sand altogether (2 to 3 mm average).

  8. Direct observation of episodic growth in an abyssal xenophyophore (Protista)

    NASA Astrophysics Data System (ADS)

    Gooday, A. J.; Bett, B. J.; Pratt, D. N.

    1993-11-01

    Three specimens of the xenophyophore Reticulammina labyrinthica were photographed on the Madeira Abyssal Plain (31°6.1'N, 21°10.9'W; 4944 m) using the Bathysnap time-lapse camera system. During the 8 month observation period, the specimens underwent an estimated 3-10 fold increase in volume. Growth occurred episodically in several distinct phases, each lasting 2-3 days, during which sediment was collected and incorporated into the test. These phases were separated by fairly regular periods of about 2 months when the organisms showed little obvious activity. The growth phases were approximately synchronous between specimens. However, it is not clear whether the periodicity and apparent synchronization of these events resulted from an external (environmental) cue or whether growth is internally controlled and the synchronization arose by chance. These unique observations, which represent the first direct measurement of growth in any abyssal organism living outside a hydrothermal vent field, suggest that xenophyophores combine test growth with deposit feeding. The tests appear to grow more quickly, and to be more active, dynamic structures, than previously believed.

  9. Geoelectrical and colour tracer monitoring with direct push observation wells

    NASA Astrophysics Data System (ADS)

    Dietrich, P.; Dietze, M.; Hoffmann, R.

    2003-04-01

    Borehole - borehole tracer tests are a hydrogeological method to characterize groundwater flow parameters. Breakthrough curves of colour tracers, injected in one borehole and measured in one or more observation wells downstream of the first, give exact but locally very limited information about groundwater flow direction and velocity. At heterogeneous subsurface conditions a large number of investigation wells and frequent sample drawing is necessary to assure recovery of the tracer, which makes the experiments very expensive. Yet, these experiments often fail or do not give sufficient information about the flow regime in the aquifer. Monitoring of salt tracers with geoelectrical methods gives an integral information about flow parameters which in most cases is a more useful information. Especially in deeper aquifers though, it is a problem to place a high number of electrodes close enough to the moving tracer to gain precise results. To assess the mentioned problems we carried out a combined geoelectrical salt and conventional colour tracer test. Our equipment for both tests was placed in direct push boreholes, which are a lot cheaper than groundwater wells, quickly installed and much less invasive. The boreholes were installed at 10 meters distance on a 120 m long profile, to form a control plane 25 meters downstream of the tracer injection. The injection took place in three different groundwater wells at a time, to provide for a good overview of the flow regime along the control plane. We show, how integral information from the geoelectrical tracer tests can be used to design a refined borehole placement for a successful colour tracer test. Our results, quite different from groundwater modelling results, strongly support the necessity to carry out precise field tracer tests for the investigation of groundwater flow parameters.

  10. Microcrack closure in rocks under stress: direct observation

    SciTech Connect

    Batzle, M.L.; Simmons, G.; Siegfried, R.W.

    1980-12-10

    Microcrack closure in rocks under increasing stress was observed directly with a scanning electron microscope. Uniaxial stresses to 300 bars were applied with a small hydraulic press to specimens of Westerly (RI) granite, both unheated and previously heat cycled to 500/sup 0/C, and of Frederick (MD) diabase, heat cycled to 700/sup 0/C. Closure characteristics (rate, final closure pressure, etc.) depend on crack orientation, shape, surface roughness, and on the nature of fracture intersections and interactions. Cracks perpendicular to the applied stress closed while those parallel to the stress tended to open. Long, narrow cracks (low aspect ratio) closed at relatively low pressures. At some intersections, one fracture would open while another simultaneously closed, depending upon their orientations. Many fractures closed uniformly even though offset by other fractures. Local stress concentrations often caused new fracturing at low applied stress. Some fractures were propped open until material lodged inside was crushed. Significant irreversible damage occurred during the first stress cycle. Closure characteristics varied significantly among the samples. The unheated granite has cracks with rough, pitted, and mismatched walls. Only partial closure occurred under stress with many sections remaining open. Crack porosity is reduced but continues to be interconnected. Fractures in the preheated granite and diabase are also irregular, but the walls are well-matched and closure is nearly complete. The cracks in the heated granite closed at lower stresses than in the diabase. As the maximum stress was approached for the heated granite, new transgranular cracks formed and preexisting cracks were enlarged. The variations in closure rate and character were also observed in strain measurements.

  11. Direct Observation of Subunit Exchange along Mature Vimentin Intermediate Filaments

    PubMed Central

    Nöding, Bernd; Herrmann, Harald; Köster, Sarah

    2014-01-01

    Actin filaments, microtubules, and intermediate filaments (IFs) are central elements of the metazoan cytoskeleton. At the molecular level, the assembly mechanism for actin filaments and microtubules is fundamentally different from that of IFs. The former two types of filaments assemble from globular proteins. By contrast, IFs assemble from tetrameric complexes of extended, half-staggered, and antiparallel oriented coiled-coils. These tetramers laterally associate into unit-length filaments; subsequent longitudinal annealing of unit-length filaments yields mature IFs. In vitro, IFs form open structures without a fixed number of tetramers per cross-section along the filament. Therefore, a central question for the structural biology of IFs is whether individual subunits can dissociate from assembled filaments and rebind at other sites. Using the fluorescently labeled IF-protein vimentin for assembly, we directly observe and quantitatively determine subunit exchange events between filaments as well as with soluble vimentin pools. Thereby we demonstrate that the cross-sectional polymorphism of donor and acceptor filaments plays an important role. We propose that in segments of donor filaments with more than the standard 32 molecules per cross-section, subunits are not as tightly bound and are predisposed to be released from the filament. PMID:25517157

  12. Direct observation of interface instability during crystal growth

    NASA Technical Reports Server (NTRS)

    Tiller, W. A.; Feigelson, R. S.; Elwell, D.

    1982-01-01

    The general aim of this investigation was to study interface stability and solute segregation phenomena during crystallization of a model system. Emphasis was to be placed on direct observational studies partly because this offered the possibility at a later stage of performing related experiments under substantially convection-free conditions in the space shuttle. The major achievements described in this report are: (1) the development of a new model system for fundamental studies of crystal growth from the melt and the measurement of a range of material parameters necessary for comparison of experiment with theory. (2) The introduction of a new method of measuring segregation coefficient using absorption of a laser beam by the liquid phase. (3) The comparison of segregation in crystals grown by gradient freezing and by pulling from the melt. (4) The introduction into the theory of solute segregation of an interface field term and comparison with experiment. (5) The introduction of the interface field term into the theories of constitutional supercooling and morphological stability and assessment of its importance.

  13. Method for observing phase objects without halos and directional shadows

    NASA Astrophysics Data System (ADS)

    Suzuki, Yoshimasa; Kajitani, Kazuo; Ohde, Hisashi

    2015-03-01

    A new microscopy method for observing phase objects without halos and directional shadows is proposed. The key optical element is an annular aperture at the front focal plane of a condenser with a larger diameter than those used in standard phase contrast microscopy. The light flux passing through the annular aperture is changed by the specimen's surface profile and then passes through an objective and contributes to image formation. This paper presents essential conditions for realizing the method. In this paper, images of colonies formed by induced pluripotent stem (iPS) cells using this method are compared with the conventional phase contrast method and the bright-field method when the NA of the illumination is small to identify differences among these techniques. The outlines of the iPS cells are clearly visible with this method, whereas they are not clearly visible due to halos when using the phase contrast method or due to weak contrast when using the bright-field method. Other images using this method are also presented to demonstrate a capacity of this method: a mouse ovum and superimposition of several different images of mouse iPS cells.

  14. Direct observations of the ACC transport across the Kerguelen Plateau

    NASA Astrophysics Data System (ADS)

    Park, Young-Hyang; Vivier, Frédéric; Roquet, Fabien; Kestenare, Elodie

    2009-09-01

    Major pathways and transport of the Antarctic Circumpolar Current (ACC) crossing the Kerguelen Plateau were directly observed during the 2009 Track cruise. The net eastward transport to the south of the Heard/McDonald Islands is estimated as 56 Sv (1 Sv = 106 m3 s-1), 43 Sv of which is tightly channelled into the Fawn Trough that appears as a predominant cross-plateau gateway of circumpolar flow associated with the Southern ACC Front (SACCF). There are also two secondary passages, with one (6 Sv) being attached to the nearshore slope just south of the Heard/McDonald Islands and the other (7 Sv) passing through the northern Princess Elizabeth Trough. With an additional 2 Sv inferred just south of the Kerguelen Islands, the transport across the entire plateau amounts to 58 Sv, accounting for ˜40% of the total ACC transport transiting through the region, 147-152 Sv, quantities consistent with other independent estimates in the Indian sector of the Southern Ocean.

  15. Direct observation of dispersion and mixing processes in microfluidic systems.

    PubMed

    Takabayashi, Yoshimasa; Fujino, Tatsuya; Korenaga, Takashi

    2008-01-01

    The diffusion phenomena, dispersion and mixing processes of the sample solute (Basic Blue 3 dye and KMnO4 aqueous solutions) were directly observed in laminar flow in glass microchannels. Quasi steady-state UV-visible absorption spectrometry was carried out using CCD camera images of the colored sample dispersion and mixing processes, and the absorbance change (DeltaAbs) was discussed based on the dimensionless parameter, tau which represents the flow time renormalized to the diffusion coefficient and the channel cross section. It was found that DeltaAbs showed almost the same tau dependence, even though the solutions and the microchannel sizes differed in laminar flow, if the microchannel fabrication method was the same. On the basis of this fundamental result, the total microchannel length required for the reaction of 2,3-diaminonaphthalene (DAN) and NO2- at a flow rate of 2 microL min(-1) was calculated, and the obtained value ( approximately 100 mm) showed very good agreement with our previous microchip research. It was concluded that both results were useful for designing the microchannel width, depth and length to control the chemical reaction time in recent microfluidic systems. PMID:18997379

  16. Using direct clinical observation to assess the quality of cesarean delivery in Afghanistan: an exploratory study

    PubMed Central

    2014-01-01

    Background As part of a National Emergency Obstetric and Newborn Care (EmONC) Needs Assessment, a special study was undertaken in July 2010 to examine the quality of cesarean deliveries in Afghanistan and examine the utility of direct clinical observation as an assessment method in low-resource settings. Methods This cross-sectional assessment of the quality of cesareans at 14 facilities in Afghanistan included a survey of surgeons regarding their routine cesarean practices, direct observation of 29 cesarean deliveries and comparison of observations with facility records for 34 additional cesareans conducted during the 3 days prior to the observation period at each facility. For both observed cases and record reviews, we assessed time intervals between specified points of care-arrival to the ward, first evaluation, detection of a complication, decision for cesarean, incision, and birth. Results All time intervals with the exception of “decision to skin incision” were longer in the record reviews than in observed cases. Prior cesarean was the most common primary indication for all cases. All mothers in both groups observed survived through one hour postpartum. Among newborns there were two stillbirths (7%) in observed births and seven (21%) record reviews. Although our sample is too small to show statistical significance, the difference is noteworthy. In six of the reviewed cesareans resulting in stillbirth, a fetal heart rate was recorded in the operating theater, although four were recorded as macerated. For the two fresh stillbirths, the cesarean surgeries were recorded as scheduled and not urgent. Conclusions Direct observation of cesarean deliveries enabled us to assess a number of preoperative, postoperative, and intraoperative procedures that are often not described in medical records in low resource settings. Comparison of observations with findings from provider interviews and facility records allowed us to infer whether observed practices were typical

  17. Direct observation of optical precursors in a cold potassium gas

    NASA Astrophysics Data System (ADS)

    Jeong, Heejeong

    This thesis considers how an electromagnetic field propagates through a dispersive linear dielectric in the case when the field is turned on suddenly. It has been predicted nearly 100 years ago that the point in the waveform where the field first turns on (the front) propagates precisely at the speed of light in vacuum. Furthermore, it is predicted that distinct wave-packets develop after the front, but before the arrival of the main part of the field (the main signal). These wave-packets are known as optical precursors. It was believed that precursors are an ultra-fast phenomena, persisting only for a few optical cycles, and that they have an exceedingly small amplitude. I describe a method to increase the duration of optical precursors into the nanosecond range using a dielectric with a narrow resonance. I also show how to increase the precursor amplitude by tuning the carrier frequency of the field near the resonance frequency of the oscillators making up the dielectric medium. The field emerging from the dielectric consists of a several-nanosecond-long spike occurring immediately after the front with near 100% transmission, which subsequently decays to a constant value expected from Beer's Law of absorption. I demonstrate, using a modern asymptotic theory, that the spike consists of both the Sommerfeld and Brillouin precursors. Thus, my measurement is the first direct observation of optical precursors. The precursor research might be useful for imaging applications requiring penetrating optical radiation, such as in biological systems, or in optical communication systems. While the asymptotic theory explains qualitatively my observations, I find that there are large quantitative disagreements. I hypothesize that these errors are due to the fact that I use a weakly-dispersive narrow-resonance medium for which this theory has never been tested. I suggest empirical fixes to the theory by comparison to my data. I also compare the asymptotic theory and data to a

  18. Direct Observations Of Microbial Activity At Extreme Pressures

    NASA Astrophysics Data System (ADS)

    Sharma, A.; Scott, J. H.; Cody, G. D.; Fogel, M.; Hazen, R. M.; Hemley, R. J.; Huntress, W. T.

    2002-12-01

    Microbial communities adapt to a wide range of pressures, temperatures, salinities, pH, and oxidation states. Although, significant attention has been focused on the effects of high and low temperature on physiology, there is some evidence that elevated pressure may also manifest interesting effects on cellular physiology, such as enzyme inactivation, cell-membrane breach, and suppression of protein interactions with various substrates. However, exactly how these factors affect intact cells is not well understood. In this study, we have adapted diamond anvil cells to explore the effects of high pressure on microbial life. We used the rate of microbial formate oxidation as a probe of metabolic viability. The utilization of formate by microorganisms is a fundamental metabolic process in anaerobic environments. We monitored in-situ microbial formate oxidation via molecular spectroscopy for Shewanella oneidensis strain MR1 and Escherichia coli strain MG1655 at high pressures (68 to 1060 MPa). At pressures of 1200 to 1600 MPa, living bacteria resided in fluid inclusions in ice-VI crystals and continued to be viable upon subsequent release to ambient pressures (0.1 MPa). Furthermore, direct microscopic observations indicate that these cells maintain their ability for cellular division upon decompression from such high pressures. Evidence of microbial viability and activity at these extreme pressures expands by an order of magnitude the range of conditions representing the habitable zone in the solar system. These results imply that pressure may not be a significant impediment to life. The maximum pressure explored in this work is equivalent to a depth of ~ 50 km below Earth's crust, or ~ 160 km in a hypothetical ocean. The pressures encountered at the depths of thick ice caps and deep crustal subsurface may not be a limiting factor for the existence of life. This suggests that deep (water/ice) layers of Europa, Callisto, or Ganymede, subduction zones on Earth, and the

  19. A software tool to analyze clinical workflows from direct observations.

    PubMed

    Schweitzer, Marco; Lasierra, Nelia; Hoerbst, Alexander

    2015-01-01

    Observational data of clinical processes need to be managed in a convenient way, so that process information is reliable, valid and viable for further analysis. However, existing tools for allocating observations fail in systematic data collection of specific workflow recordings. We present a software tool which was developed to facilitate the analysis of clinical process observations. The tool was successfully used in the project OntoHealth, to build, store and analyze observations of diabetes routine consultations. PMID:26262417

  20. Observation of Anisotropy in Cosmic-Ray Arrival Directions with the IceCube Observatory

    NASA Astrophysics Data System (ADS)

    McNally, Frank

    We provide an update on the continued observation of anisotropy in the arrival direction distribution of cosmic rays in the southern hemisphere. With its in-ice and IceTop detector, the IceCube Observatory recorded more than 250 billion and 170 million events, respectively, between May 2009 and May 2014. In this large data set, we observe significant small-scale structure on angular scales down to 3°, the median angular resolution of the IceCube detector for cosmic rays. The expanded dataset also allows for a more detailed study of the anisotropy for various cosmic-ray median energies. The large-scale structure observed with the in-ice detector at median energies near 20 TeV changes at energies above 100 TeV, with the high-energy skymaps showing a strong deficit also present in the IceTop 2 PeV sample.

  1. A Study of Student Teaching Using Direct Observation.

    ERIC Educational Resources Information Center

    Coker, Joan G.; Coker, Homer

    Thirty-three student teachers were observed in elementary school classrooms to determine if they manifested 16 interactive behaviors identified as desirable by college of education faculty. Teaching assistants used the Georgia Assessment of Teaching Effectiveness (GATE), an instrument which requires the observers to objectively record, but not…

  2. Determination of acceleration mechanism characteristics directly and nonparametrically from observations: Application to supernova remnants

    NASA Astrophysics Data System (ADS)

    Petrosian, Vahé; Chen, Qingrong

    2014-05-01

    We have developed an inversion method for determination of the characteristics of the acceleration mechanism directly and nonparametrically from observations, in contrast to the usual forward fitting of parametric model variables to observations. In two recent papers [V. Petrosian and Q. Chen, Astrophys. J. 712, L131 (2010); Q. Chen and V. Petrosian, Astrophys. J. 777, 33 (2013)], we demonstrated the efficacy of this inversion method by its application to acceleration of electrons in solar flares based on stochastic acceleration by turbulence. Here we explore its application for determining the characteristics of shock acceleration in supernova remnants (SNRs) based on the electron spectra deduced from the observed nonthermal radiation from SNRs and the spectrum of the cosmic ray electrons observed near the Earth. These spectra are related by the process of escape of the electrons from SNRs and energy loss during their transport in the Galaxy. Thus, these observations allow us to determine spectral characteristics of the momentum and pitch angle diffusion coefficients, which play crucial roles in both direct acceleration by turbulence and in high Mach number shocks. Assuming that the average electron spectrum deduced from a few well-known SNRs is representative of those in the solar neighborhood, we find interesting discrepancies between our deduced forms for these coefficients and those expected from well-known wave-particle interactions. This may indicate that the standard assumptions made in the treatment of shock acceleration need revision. In particular, the escape of particles from SNRs may be more complex than generally assumed.

  3. Genetic-Algorithm Discovery of a Direct-Gap and Optically Allowed Superstructure from Indirect-Gap Si and Ge Semiconductors

    SciTech Connect

    d'Avezac, M.; Luo, J. W.; Chanier, T.; Zunger, A.

    2012-01-13

    Combining two indirect-gap materials - with different electronic and optical gaps - to create a direct gap material represents an ongoing theoretical challenge with potentially rewarding practical implications, such as optoelectronics integration on a single wafer. We provide an unexpected solution to this classic problem, by spatially melding two indirect-gap materials (Si and Ge) into one strongly dipole-allowed direct-gap material. We leverage a combination of genetic algorithms with a pseudopotential Hamiltonian to search through the astronomic number of variants of Si{sub n}/Ge{sub m}/.../Si{sub p}/Ge{sub q} superstructures grown on (001) Si{sub 1-x}Ge{sub x}. The search reveals a robust configurational motif - SiGe{sub 2}Si{sub 2}Ge{sub 2}SiGe{sub n} on (001) Si{sub x}Ge{sub 1-x} substrate (x {le} 0.4) presenting a direct and dipole-allowed gap resulting from an enhanced {Gamma}-X coupling at the band edges.

  4. Physical Activity Surveillance in Parks Using Direct Observation

    PubMed Central

    McKenzie, Thomas L.; Cohen, Deborah; Evenson, Kelly R.; Golinelli, Daniela; Hillier, Amy; Lapham, Sandra C.; Williamson, Stephanie

    2014-01-01

    Introduction Primary features of observational public health surveillance instruments are that they are valid, can reliably estimate physical activity behaviors, and are useful across diverse geographic settings and seasons by different users. Previous studies have reported the validity and reliability of Systematic Observation of Play and Recreation in Communities (SOPARC) to estimate park and user characteristics. The purpose of this investigation was to establish the use of SOPARC as a surveillance instrument and to situate the findings from the study in the context of the previous literature. Methods We collected data by using SOPARC for more than 3 years in 4 locations: Philadelphia, Pennsylvania; Columbus, Ohio; Chapel Hill/Durham, North Carolina; and Albuquerque, New Mexico during spring, summer, and autumn. Results We observed a total of 35,990 park users with an overall observer reliability of 94% (range, 85%–99%) conducted on 15% of the observations. We monitored the proportion of park users engaging in moderate-to-vigorous physical activity (MVPA) and found marginal differences in MVPA by both city and season. Park users visited parks significantly more on weekend days than weekdays and visitation rates tended to be lower during summer than spring. Conclusion SOPARC is a highly reliable observation instrument that can be used to collect data across diverse geographic settings and seasons by different users and has potential as a surveillance system. PMID:24384304

  5. Direct observation of defect structure in protein crystals by atomic force and transmission electron microscopy.

    PubMed Central

    Devaud, G; Furcinitti, P S; Fleming, J C; Lyon, M K; Douglas, K

    1992-01-01

    We have examined the structure of S-layers isolated from Sulfolobus acidocaldarius using atomic force microscopy (AFM) and transmission electron microscopy (TEM). From the AFM images, we were able to directly observe individual dimers of the crystal, defects in the crystal structure, and twin boundaries. We have identified two types of boundaries, one defined by a mirror plane and the other by a glide plane. This work shows that twin boundaries are highly structured regions that are directly related to the organization of units within each crystal domain. Projection maps from TEM images have shown that there are significant differences in the final average maps has allowed us to relate high magnification views obtained by AFM to the relatively high resolution information obtained by electron microscopy and image processing. Images FIGURE 1 FIGURE 2 FIGURE 3 FIGURE 4 FIGURE 5 FIGURE 6 PMID:1420904

  6. Direct observation shows superposition and large scale flexibility within cytoplasmic dynein motors moving along microtubules

    PubMed Central

    Imai, Hiroshi; Shima, Tomohiro; Sutoh, Kazuo; Walker, Matthew L.; Knight, Peter J.; Kon, Takahide; Burgess, Stan A.

    2015-01-01

    Cytoplasmic dynein is a dimeric AAA+ motor protein that performs critical roles in eukaryotic cells by moving along microtubules using ATP. Here using cryo-electron microscopy we directly observe the structure of Dictyostelium discoideum dynein dimers on microtubules at near-physiological ATP concentrations. They display remarkable flexibility at a hinge close to the microtubule binding domain (the stalkhead) producing a wide range of head positions. About half the molecules have the two heads separated from one another, with both leading and trailing motors attached to the microtubule. The other half have the two heads and stalks closely superposed in a front-to-back arrangement of the AAA+ rings, suggesting specific contact between the heads. All stalks point towards the microtubule minus end. Mean stalk angles depend on the separation between their stalkheads, which allows estimation of inter-head tension. These findings provide a structural framework for understanding dynein's directionality and unusual stepping behaviour. PMID:26365535

  7. Direct observation shows superposition and large scale flexibility within cytoplasmic dynein motors moving along microtubules.

    PubMed

    Imai, Hiroshi; Shima, Tomohiro; Sutoh, Kazuo; Walker, Matthew L; Knight, Peter J; Kon, Takahide; Burgess, Stan A

    2015-01-01

    Cytoplasmic dynein is a dimeric AAA(+) motor protein that performs critical roles in eukaryotic cells by moving along microtubules using ATP. Here using cryo-electron microscopy we directly observe the structure of Dictyostelium discoideum dynein dimers on microtubules at near-physiological ATP concentrations. They display remarkable flexibility at a hinge close to the microtubule binding domain (the stalkhead) producing a wide range of head positions. About half the molecules have the two heads separated from one another, with both leading and trailing motors attached to the microtubule. The other half have the two heads and stalks closely superposed in a front-to-back arrangement of the AAA(+) rings, suggesting specific contact between the heads. All stalks point towards the microtubule minus end. Mean stalk angles depend on the separation between their stalkheads, which allows estimation of inter-head tension. These findings provide a structural framework for understanding dynein's directionality and unusual stepping behaviour. PMID:26365535

  8. DIRECT OBSERVATION OF A COROTATING INTERACTION REGION BY THREE SPACECRAFT

    SciTech Connect

    Tappin, S. J. Howard, T. A

    2009-09-10

    White-light observations of interplanetary disturbances have been dominated by interplanetary coronal mass ejections (ICMEs). This is because the other type of disturbance, the corotating interaction region (CIR), has proved difficult to detect using white-light imagers. Recently, a number of papers have appeared presenting CIR observations using the Solar Terrestrial Relations Observatory (STEREO) Heliospheric Imagers (HIs), but have mostly only focused on a single spacecraft and imager. In this paper, we present observations of a single CIR that was observed by all three current white-light heliospheric imagers (SMEI and both STEREO HIs), as well as the in situ instruments on both STEREO satellites and ACE. We begin with a discussion of the geometry of the CIR structure, and show how the apparent leading edge structure is expected to change as it corotates relative to the observer. We use these calculations to predict elongation-time profiles for CIRs of different speeds for each of the imagers, and also to predict the arrival times at the in situ instruments. We show that although all three measured different parts, they combine to produce a self-consistent picture of the CIR. Finally, we offer some thoughts on why CIRs have proved so difficult to detect in white-light heliospheric images.

  9. Clear Direction. The Montessori Observer. Volume 32, Number 2

    ERIC Educational Resources Information Center

    International Montessori Society (NJ3), 2011

    2011-01-01

    "The Montessori Observer" is mailed four times each year, in March, May, September and November, to Society members throughout the world. The purpose is to provide news and information about the Society's work in Montessori education, and to extend awareness of Montessori principles throughout the world. This issue contains a feature article,…

  10. Future directions in X-ray/gamma-ray observations

    NASA Technical Reports Server (NTRS)

    Kniffen, D. A.

    1982-01-01

    Facilities available for X ray and gamma ray astronomical observations in the late 1980s are described, with an emphasis on NASA programs. Current European programs for launching Rosat and Exosat will provide coverage in the 0.4-60 keV energy range. The proposed NASA advanced X ray astrophysics facility is intended to cover the 0.1-8 keV range with higher than 0.5 arcsec resolution. The Japanese Astro-B, scheduled for launch in 1983, observes in the 1-60 keV range. X ray and gamma ray observations are also scheduled for Spacelab flights. The French-Soviet Gamma-1 spark chamber high energy gamma ray telescope is intended for LEO orbit and observations in the energy range above 50 MeV with a 2 deg, 1-5 arcmin resolution. The NASA gamma ray observatory is set for 1988 launch and will feature four instruments to monitor the 60 keV-300 GeV range. Balloon-borne instrumentation will also be launched, with attention given to the medium gamma ray energy range from 1-30 MeV.

  11. Future directions in X-ray/gamma-ray observations

    NASA Astrophysics Data System (ADS)

    Kniffen, D. A.

    Facilities available for X ray and gamma ray astronomical observations in the late 1980s are described, with an emphasis on NASA programs. Current European programs for launching Rosat and Exosat will provide coverage in the 0.4-60 keV energy range. The proposed NASA advanced X ray astrophysics facility is intended to cover the 0.1-8 keV range with higher than 0.5 arcsec resolution. The Japanese Astro-B, scheduled for launch in 1983, observes in the 1-60 keV range. X ray and gamma ray observations are also scheduled for Spacelab flights. The French-Soviet Gamma-1 spark chamber high energy gamma ray telescope is intended for LEO orbit and observations in the energy range above 50 MeV with a 2 deg, 1-5 arcmin resolution. The NASA gamma ray observatory is set for 1988 launch and will feature four instruments to monitor the 60 keV-300 GeV range. Balloon-borne instrumentation will also be launched, with attention given to the medium gamma ray energy range from 1-30 MeV.

  12. Observations of directional gamma prime coarsening during engine operation

    NASA Technical Reports Server (NTRS)

    Draper, Susan L.; Hull, David R.; Dreshfield, Robert L.

    1987-01-01

    Two alloys with negative mismatch parameters, NASAIR 100 and a modified NASAIR 100 called Alloy 3 were run as turbine blades in an experimental ground based Garret TFE731 engine for up to 200 hr. The directional coarsening of gamma prime (rafting) that developed during engine testing was analyzed and compared to previous research from laboratory tests. The blades were found to be rafted normal to the centrifugal stress axis over much of the span, but near the surfaces, the blades were found to be rafted parallel to the centrifugal stress axis for certain cycles. Representative photomicrographs of the blades and the effects of stress and temperature on raft formation are shown.

  13. Direct Observation of the Three-State Folding of a Single Protein Molecule

    NASA Astrophysics Data System (ADS)

    Cecconi, Ciro; Shank, Elizabeth A.; Bustamante, Carlos; Marqusee, Susan

    2005-09-01

    We used force-measuring optical tweezers to induce complete mechanical unfolding and refolding of individual Escherichia coli ribonuclease H (RNase H) molecules. The protein unfolds in a two-state manner and refolds through an intermediate that correlates with the transient molten globule-like intermediate observed in bulk studies. This intermediate displays unusual mechanical compliance and unfolds at substantially lower forces than the native state. In a narrow range of forces, the molecule hops between the unfolded and intermediate states in real time. Occasionally, hopping was observed to stop as the molecule crossed the folding barrier directly from the intermediate, demonstrating that the intermediate is on-pathway. These studies allow us to map the energy landscape of RNase H.

  14. Direct observation of nanoparticle-cancer cell nucleus interactions.

    PubMed

    Dam, Duncan Hieu M; Lee, Jung Heon; Sisco, Patrick N; Co, Dick T; Zhang, Ming; Wasielewski, Michael R; Odom, Teri W

    2012-04-24

    We report the direct visualization of interactions between drug-loaded nanoparticles and the cancer cell nucleus. Nanoconstructs composed of nucleolin-specific aptamers and gold nanostars were actively transported to the nucleus and induced major changes to the nuclear phenotype via nuclear envelope invaginations near the site of the construct. The number of local deformations could be increased by ultrafast, light-triggered release of the aptamers from the surface of the gold nanostars. Cancer cells with more nuclear envelope folding showed increased caspase 3 and 7 activity (apoptosis) as well as decreased cell viability. This newly revealed correlation between drug-induced changes in nuclear phenotype and increased therapeutic efficacy could provide new insight for nuclear-targeted cancer therapy. PMID:22424173

  15. Observations of directional gamma prime coarsening during engine operation

    NASA Technical Reports Server (NTRS)

    Draper, S.; Hull, D.; Dreshfield, R.

    1989-01-01

    Two alloys, NASAIR 100 and a modified NASAIR 100 called Alloy 3, were run as turbine blades in an experimental ground-based Garrett TFE731 engine for up to 200 hours. The stress induced directional coarsening of gamma-prime (rafting) that developed during engine testing was analyzed and compared to previous research from laboratory tests. The blades were found to have formed a lamellar structure, the lamellae being normal to the centrifugal stress axis over much of the span. However, near the surfaces, the blades were found to have formed lamellae parallel to the centrifugal stress axis for certain cycles. Representative photomicrographs of the blades and the effects of stress and temperature on lamellae formation are shown.

  16. Galileo NIMS Direct Observations of the SL-9 Fireballs

    NASA Technical Reports Server (NTRS)

    Carlson, R. W.; Weissman, P. R.; Hui, J.; Segura, M.; Johnson, T. V.; Smythe, W. D.; Baines, K. H.; Drossart, P.; Encrenaz, T.; Leader, F.; Mehlman, R.

    1995-01-01

    The Galileo spacecraft was situated 1.8 AU from Jupiter, at a phase angle of 51 deg, providing a direct view of the impacts of the comet fragments with the planet. Low resolution infrared spectra in the 1 to 5 micron range were recorded for several of the events, which can be used to study the early evolution of the fireballs. Preliminary analysis of the data received for the G event show an initial fireball temperature of greater than 5000 K and an effective source diameter of less than 10 km. These spectra show absorption by molecular hydrogen and methane which place the upper emitting surface in the stratosphere, above the ammonia cloud level. As time progresses, the fireball cools and the effective diameter of the radiating area increases at roughly 2 km/sec. In 30 seconds, the fireball cools to approximately 1000 k and exhibits a diameter of about 100 km.

  17. Direct Observation of Capillary Condensation of a Solid

    NASA Astrophysics Data System (ADS)

    Qiao, Ying; Christenson, Hugo K.

    2001-04-01

    We describe the direct condensation of a solid from vapor in an annular mica wedge. Neo-pentanol initially condenses as a liquid from 8 to 57 °C (the melting point Tm), followed by nucleation of a solid from vapor for T<45 °C. Menthol \\(Tm = 42 °C\\) gives only liquid condensates down to 12 °C. The adsorbed films of neo-pentanol, which unlike those of menthol show layering transitions, and the disordered crystalline phase of bulk neo-pentanol appear to facilitate condensation of the solid phase. There is evidence for a change in the nature of the solid neo-pentanol condensate with T.

  18. Direct Observation of Ultralow Vertical Emittance using a Vertical Undulator

    SciTech Connect

    Wootton, Kent

    2015-09-17

    In recent work, the first quantitative measurements of electron beam vertical emittance using a vertical undulator were presented, with particular emphasis given to ultralow vertical emittances [K. P. Wootton, et al., Phys. Rev. ST Accel. Beams, 17, 112802 (2014)]. Using this apparatus, a geometric vertical emittance of 0.9 #6;± 0.3 pm rad has been observed. A critical analysis is given of measurement approaches that were attempted, with particular emphasis on systematic and statistical uncertainties. The method used is explained, compared to other techniques and the applicability of these results to other scenarios discussed.

  19. Microwave observations of Saturn's rings: anisotropy in directly transmitted and scattered saturnian thermal emission

    NASA Astrophysics Data System (ADS)

    Dunn, David E.; Molnar, Lawrence A.; Niehof, Jon T.; de Pater, Imke; Lissauer, Jack J.

    2004-09-01

    We present a new Very Large Array (VLA) image of Saturn, made from data taken in October 1998 at a wavelength of λ3.6 cm. The moderate ring opening angle ( B≈15°) allows us to explore direct transmission of microwave photons through the A and C rings. We find a strong asymmetry of photons transmitted through the A ring, but not in the C ring, a new diagnostic of wake structure in the ring particles. We also find a weak asymmetry between east and west for the far side of the ansae. To facilitate quantitative comparison between dynamic models of the A ring and radio observations, we extend our Monte Carlo radiative transfer code (described in Dunn et al., 2002, Icarus 160, 132-160) to include idealized wakes. We show the idealized model can reproduce the properties of dynamic simulations in directly transmitted light. We examine the model behavior in directly transmitted and scattered light over a range of physical and geometric wake parameters. Finally, we present a wake model with a plausible set of physical parameters that quantitatively reproduces the observed intensity and asymmetry of the A ring both across the planet and in the ansae.

  20. Direct observation of intermediate states in model membrane fusion

    NASA Astrophysics Data System (ADS)

    Keidel, Andrea; Bartsch, Tobias F.; Florin, Ernst-Ludwig

    2016-03-01

    We introduce a novel assay for membrane fusion of solid supported membranes on silica beads and on coverslips. Fusion of the lipid bilayers is induced by bringing an optically trapped bead in contact with the coverslip surface while observing the bead’s thermal motion with microsecond temporal and nanometer spatial resolution using a three-dimensional position detector. The probability of fusion is controlled by the membrane tension on the particle. We show that the progression of fusion can be monitored by changes in the three-dimensional position histograms of the bead and in its rate of diffusion. We were able to observe all fusion intermediates including transient fusion, formation of a stalk, hemifusion and the completion of a fusion pore. Fusion intermediates are characterized by axial but not lateral confinement of the motion of the bead and independently by the change of its rate of diffusion due to the additional drag from the stalk-like connection between the two membranes. The detailed information provided by this assay makes it ideally suited for studies of early events in pure lipid bilayer fusion or fusion assisted by fusogenic molecules.

  1. Direct observation of intermediate states in model membrane fusion.

    PubMed

    Keidel, Andrea; Bartsch, Tobias F; Florin, Ernst-Ludwig

    2016-01-01

    We introduce a novel assay for membrane fusion of solid supported membranes on silica beads and on coverslips. Fusion of the lipid bilayers is induced by bringing an optically trapped bead in contact with the coverslip surface while observing the bead's thermal motion with microsecond temporal and nanometer spatial resolution using a three-dimensional position detector. The probability of fusion is controlled by the membrane tension on the particle. We show that the progression of fusion can be monitored by changes in the three-dimensional position histograms of the bead and in its rate of diffusion. We were able to observe all fusion intermediates including transient fusion, formation of a stalk, hemifusion and the completion of a fusion pore. Fusion intermediates are characterized by axial but not lateral confinement of the motion of the bead and independently by the change of its rate of diffusion due to the additional drag from the stalk-like connection between the two membranes. The detailed information provided by this assay makes it ideally suited for studies of early events in pure lipid bilayer fusion or fusion assisted by fusogenic molecules. PMID:27029285

  2. Direct observation of intermediate states in model membrane fusion

    PubMed Central

    Keidel, Andrea; Bartsch, Tobias F.; Florin, Ernst-Ludwig

    2016-01-01

    We introduce a novel assay for membrane fusion of solid supported membranes on silica beads and on coverslips. Fusion of the lipid bilayers is induced by bringing an optically trapped bead in contact with the coverslip surface while observing the bead’s thermal motion with microsecond temporal and nanometer spatial resolution using a three-dimensional position detector. The probability of fusion is controlled by the membrane tension on the particle. We show that the progression of fusion can be monitored by changes in the three-dimensional position histograms of the bead and in its rate of diffusion. We were able to observe all fusion intermediates including transient fusion, formation of a stalk, hemifusion and the completion of a fusion pore. Fusion intermediates are characterized by axial but not lateral confinement of the motion of the bead and independently by the change of its rate of diffusion due to the additional drag from the stalk-like connection between the two membranes. The detailed information provided by this assay makes it ideally suited for studies of early events in pure lipid bilayer fusion or fusion assisted by fusogenic molecules. PMID:27029285

  3. Direct Experimental Observation of a Practical AC Zeeman Force

    NASA Astrophysics Data System (ADS)

    Fancher, Charles; Pyle, Andrew; Rotunno, Andrew; Du, Shuangli; Aubin, Seth

    2016-05-01

    We present measurements of the spin-dependent AC Zeeman force produced by microwave magnetic near-field gradients on an atom chip. We measure the AC Zeeman force on ultracold 87 Rb atoms by observing its effect on the motion of atoms in free-fall and on those confined in a trap. We have studied the force as a function of microwave frequency detuning from a hyperfine transition at 6.8 GHz at several magnetic field strengths and have observed its characteristic bipolar and resonant features predicted by two-level dressed atom theory. We find that the force is several times the strength of gravity in our setup, and that it can be targeted to a specific hyperfine transition while leaving other hyperfine states and transitions relatively unaffected. We find that our measurements are reasonably consistent with theory and are working towards a parameter-free comparison. AC Zeeman potentials offer the possibility of targeting qualitatively different trapping potentials to different spin states, a capability currently absent from the toolbox of atomic quantum control techniques. In particular, an AC Zeeman potential could be used as the beamsplitter for a spin-dependent atom interferometer or for engineering a quantum gate. Work supported by AFOSR and W&M, and in part by AFRL.

  4. Providers' response to child eating behaviors: A direct observation study.

    PubMed

    Tovar, Alison; Vaughn, Amber E; Fallon, Megan; Hennessy, Erin; Burney, Regan; Østbye, Truls; Ward, Dianne S

    2016-10-01

    Child care providers play an important role in feeding young children, yet little is known about children's influence on providers' feeding practices. This qualitative study examines provider and child (18 months -4 years) feeding interactions. Trained data collectors observed 200 eating occasions in 48 family child care homes and recorded providers' responses to children's meal and snack time behaviors. Child behaviors initiating provider feeding practices were identified and practices were coded according to higher order constructs identified in a recent feeding practices content map. Analysis examined the most common feeding practices providers used to respond to each child behavior. Providers were predominately female (100%), African-American (75%), and obese (77%) and a third of children were overweight/obese (33%). Commonly observed child behaviors were: verbal and non-verbal refusals, verbal and non-verbal acceptance, being "all done", attempts for praise/attention, and asking for seconds. Children's acceptance of food elicited more autonomy supportive practices vs. coercive controlling. Requests for seconds was the most common behavior, resulting in coercive controlling practices (e.g., insisting child eat certain food or clean plate). Future interventions should train providers on responding to children's behaviors and helping children become more aware of internal satiety and hunger cues. PMID:27328098

  5. Directly observing continuum emission from self-gravitating spiral waves

    NASA Astrophysics Data System (ADS)

    Hall, Cassandra; Forgan, Duncan; Rice, Ken; Harries, Tim J.; Klaassen, Pamela D.; Biller, Beth

    2016-05-01

    We use a simple, self-consistent, self-gravitating semi-analytic disc model to conduct an examination of the parameter space in which self-gravitating discs may exist. We then use Monte Carlo radiative transfer to generate synthetic Atacama Large Millimeter/submillimeter Array (ALMA) images of these self-gravitating discs to determine the subset of this parameter space in which they generate non-axisymmetric structure that is potentially detectable by ALMA. Recently, several transition discs have been observed to have non-axisymmetric structure that extends out to large radii. It has been suggested that one possible origin of these asymmetries could be spiral density waves induced by disc self-gravity. We use our simple model to see if these discs exist in the region of parameter space where self-gravity could feasibly explain these spiral features. We find that for self-gravity to play a role in these systems typically requires a disc mass around an order of magnitude higher than the observed disc masses for the systems. The spiral amplitudes produced by self-gravity in the local approximation are relatively weak when compared to amplitudes produced by tidal interactions, or spirals launched at Lindblad resonances due to embedded planets in the disc. As such, we ultimately caution against diagnosing spiral features as being due to self-gravity, unless the disc exists in the very narrow region of parameter space where the spiral wave amplitudes are large enough to produce detectable features, but not so large as to cause the disc to fragment.

  6. An Unroofing Method to Observe the Cytoskeleton Directly at Molecular Resolution Using Atomic Force Microscopy.

    PubMed

    Usukura, Eiji; Narita, Akihiro; Yagi, Akira; Ito, Shuichi; Usukura, Jiro

    2016-01-01

    An improved unroofing method enabled the cantilever of an atomic force microscope (AFM) to reach directly into a cell to visualize the intracellular cytoskeletal actin filaments, microtubules, clathrin coats, and caveolae in phosphate-buffered saline (PBS) at a higher resolution than conventional electron microscopy. All of the actin filaments clearly exhibited a short periodicity of approximately 5-6 nm, which was derived from globular actins linked to each other to form filaments, as well as a long helical periodicity. The polarity of the actin filaments appeared to be determined by the shape of the periodic striations. Microtubules were identified based on their thickness. Clathrin coats and caveolae were observed on the cytoplasmic surface of cell membranes. The area containing clathrin molecules and their terminal domains was directly visualized. Characteristic ridge structures located at the surface of the caveolae were observed at high resolution, similar to those observed with electron microscopy (EM). Overall, unroofing allowed intracellular AFM imaging in a liquid environment with a level of quality equivalent or superior to that of EM. Thus, AFMs are anticipated to provide cutting-edge findings in cell biology and histology. PMID:27273367

  7. An Unroofing Method to Observe the Cytoskeleton Directly at Molecular Resolution Using Atomic Force Microscopy

    PubMed Central

    Usukura, Eiji; Narita, Akihiro; Yagi, Akira; Ito, Shuichi; Usukura, Jiro

    2016-01-01

    An improved unroofing method enabled the cantilever of an atomic force microscope (AFM) to reach directly into a cell to visualize the intracellular cytoskeletal actin filaments, microtubules, clathrin coats, and caveolae in phosphate-buffered saline (PBS) at a higher resolution than conventional electron microscopy. All of the actin filaments clearly exhibited a short periodicity of approximately 5–6 nm, which was derived from globular actins linked to each other to form filaments, as well as a long helical periodicity. The polarity of the actin filaments appeared to be determined by the shape of the periodic striations. Microtubules were identified based on their thickness. Clathrin coats and caveolae were observed on the cytoplasmic surface of cell membranes. The area containing clathrin molecules and their terminal domains was directly visualized. Characteristic ridge structures located at the surface of the caveolae were observed at high resolution, similar to those observed with electron microscopy (EM). Overall, unroofing allowed intracellular AFM imaging in a liquid environment with a level of quality equivalent or superior to that of EM. Thus, AFMs are anticipated to provide cutting-edge findings in cell biology and histology. PMID:27273367

  8. Direct observation of dynamic shear jamming in dense suspensions.

    PubMed

    Peters, Ivo R; Majumdar, Sayantan; Jaeger, Heinrich M

    2016-04-14

    Liquid-like at rest, dense suspensions of hard particles can undergo striking transformations in behaviour when agitated or sheared. These phenomena include solidification during rapid impact, as well as strong shear thickening characterized by discontinuous, orders-of-magnitude increases in suspension viscosity. Much of this highly non-Newtonian behaviour has recently been interpreted within the framework of a jamming transition. However, although jamming indeed induces solid-like rigidity, even a strongly shear-thickened state still flows and thus cannot be fully jammed. Furthermore, although suspensions are incompressible, the onset of rigidity in the standard jamming scenario requires an increase in particle density. Finally, whereas shear thickening occurs in the steady state, impact-induced solidification is transient. As a result, it has remained unclear how these dense suspension phenomena are related and how they are connected to jamming. Here we resolve this by systematically exploring both the steady-state and transient regimes with the same experimental system. We demonstrate that a fully jammed, solid-like state can be reached without compression and instead purely with shear, as recently proposed for dry granular systems. This state is created by transient shear-jamming fronts, which we track directly. We also show that shear stress, rather than shear rate, is the key control parameter. From these findings we map out a state diagram with particle density and shear stress as variables. We identify discontinuous shear thickening with a marginally jammed regime just below the onset of full, solid-like jamming. This state diagram provides a unifying framework, compatible with prior experimental and simulation results on dense suspensions, that connects steady-state and transient behaviour in terms of a dynamic shear-jamming process. PMID:27042934

  9. Direct observation of dynamic shear jamming in dense suspensions

    NASA Astrophysics Data System (ADS)

    Peters, Ivo R.; Majumdar, Sayantan; Jaeger, Heinrich M.

    2016-04-01

    Liquid-like at rest, dense suspensions of hard particles can undergo striking transformations in behaviour when agitated or sheared. These phenomena include solidification during rapid impact, as well as strong shear thickening characterized by discontinuous, orders-of-magnitude increases in suspension viscosity. Much of this highly non-Newtonian behaviour has recently been interpreted within the framework of a jamming transition. However, although jamming indeed induces solid-like rigidity, even a strongly shear-thickened state still flows and thus cannot be fully jammed. Furthermore, although suspensions are incompressible, the onset of rigidity in the standard jamming scenario requires an increase in particle density. Finally, whereas shear thickening occurs in the steady state, impact-induced solidification is transient. As a result, it has remained unclear how these dense suspension phenomena are related and how they are connected to jamming. Here we resolve this by systematically exploring both the steady-state and transient regimes with the same experimental system. We demonstrate that a fully jammed, solid-like state can be reached without compression and instead purely with shear, as recently proposed for dry granular systems. This state is created by transient shear-jamming fronts, which we track directly. We also show that shear stress, rather than shear rate, is the key control parameter. From these findings we map out a state diagram with particle density and shear stress as variables. We identify discontinuous shear thickening with a marginally jammed regime just below the onset of full, solid-like jamming. This state diagram provides a unifying framework, compatible with prior experimental and simulation results on dense suspensions, that connects steady-state and transient behaviour in terms of a dynamic shear-jamming process.

  10. Variability of the directly observed, middepth subpolar North Atlantic circulation

    NASA Astrophysics Data System (ADS)

    Palter, Jaime B.; Caron, Charles-André; Law, Kara Lavender; Willis, Joshua K.; Trossman, David S.; Yashayaev, Igor M.; Gilbert, Denis

    2016-03-01

    Satellite views of the ocean have suggested a decline of the subpolar North Atlantic surface circulation during the 1990s and 2000s. This was a period of unprecedented observational capacity in the basin, thanks to the presence of many hundreds of profiling floats. We use more than 40,000 subsurface displacements of these floats to characterize the circulation at 1000 m depth, and its evolution from 1997-2013. We show a statistically significant slowdown in the Labrador Sea boundary currents of -0.8 cm s-1 per decade (95% confidence interval of -1.4 to -0.15 cm s—1 per decade, a conservative estimate of the uncertainty). Otherwise, the middepth circulation field was largely stable. Our analysis of the location where the North Atlantic Current crosses the Mid-Atlantic Ridge shows that profiling floats can reveal steering by bathymetric features, but do not reveal of decadal variability in the position where the current crosses the ridge.

  11. Direct observation of OH formation from stabilised Criegee intermediates.

    PubMed

    Novelli, A; Vereecken, L; Lelieveld, J; Harder, H

    2014-10-01

    The syn-CH3CHOO Criegee intermediate formed from the ozonolysis of propene and (E)-2-butene was detected via unimolecular decomposition and subsequent detection of OH radicals by a LIF-FAGE instrument. An observed time dependent OH concentration profile was analysed using a detailed model focusing on the speciated chemistry of Criegee intermediates based on the recent literature. The absolute OH concentration was found to depend on the steady state concentration of syn-CH3CHOO at the injection point while the time dependence of the OH concentration profile was influenced by the sum of the rates of unimolecular decomposition of syn-CH3CHOO and wall loss. By varying the most relevant parameters influencing the SCI chemistry in the model and based on the temporal OH concentration profile, the unimolecular decomposition rate k (293 K) of syn-CH3CHOO was shown to lie within the range 3-30 s(-1), where a value of 20 ± 10 s(-1) yields the best agreement with the CI chemistry literature. PMID:25119645

  12. Direct Observation of Kinetic Pathways of Biomolecular Recognition.

    PubMed

    Choudhury, Susobhan; Batabyal, Subrata; Mondal, Prasanna Kumar; Singh, Priya; Lemmens, Peter; Pal, Samir Kumar

    2015-11-01

    The pathways of molecular recognition, which is a central event in all biological processes, belong to the most important subjects of contemporary research in biomolecular science. By using fluorescence spectroscopy in a microfluidics channel, it can be determined that molecular recognition of α-chymotrypsin in hydrous surroundings at two different pH values (3.6 and 6.3) follows two distinctly different pathways. Whereas one corroborates an induced-fit model (pH 3.6), the other one (pH 6.3) is consistent with the selected-fit model of biomolecular recognition. The role of massive structural perturbations of differential recognition pathways could be ruled out by earlier XRD studies, rather was consistent with the femtosecond-resolved observation of dynamic flexibility of the protein at different pH values. At low concentrations of ligands, the selected-fit model dominates, whereas increasing the ligand concentration leads to the induced-fit model. From molecular modelling and experimental results, the timescale associated with the conformational flexibility of the protein plays a key role in the selection of a pathway in biomolecular recognition. PMID:26367136

  13. Direct observation of catch bonds involving cell-adhesion molecules

    NASA Astrophysics Data System (ADS)

    Marshall, Bryan T.; Long, Mian; Piper, James W.; Yago, Tadayuki; McEver, Rodger P.; Zhu, Cheng

    2003-05-01

    Bonds between adhesion molecules are often mechanically stressed. A striking example is the tensile force applied to selectin-ligand bonds, which mediate the tethering and rolling of flowing leukocytes on vascular surfaces. It has been suggested that force could either shorten bond lifetimes, because work done by the force could lower the energy barrier between the bound and free states (`slip'), or prolong bond lifetimes by deforming the molecules such that they lock more tightly (`catch'). Whereas slip bonds have been widely observed, catch bonds have not been demonstrated experimentally. Here, using atomic force microscopy and flow-chamber experiments, we show that increasing force first prolonged and then shortened the lifetimes of P-selectin complexes with P-selectin glycoprotein ligand-1, revealing both catch and slip bond behaviour. Transitions between catch and slip bonds might explain why leukocyte rolling on selectins first increases and then decreases as wall shear stress increases. This dual response to force provides a mechanism for regulating cell adhesion under conditions of variable mechanical stress.

  14. Direct observation of resonance effects in laser cluster interactions

    SciTech Connect

    Zweiback, J

    1999-06-01

    Time resolved dynamics of high intensity laser interactions with atomic clusters have been studied with both theoretical analysis and experiment. A short-pulse Ti:sapphire laser system, which could produce 50 mJ of energy in a 50 fs pulse, was built to perform these experiments. The laser used a novel single grating stretcher and was pumped, in part, by a custom Nd:YLF laser system, including 19 mm Nd:YLF amplifiers. It was found that there is an optimal pulse width to maximize absorption for a given cluster size. This optimal pulse width ranged from 400 fs for 85 A radius xenon clusters to 1.2 ps for 205 {angstrom} radius xenon clusters. Using a pump-probe configuration, the absorption of the probe radiation was observed to reach a maximum for a particular time delay between pump and probe, dependent on the cluster size. The delay for peak absorption was 800, 1400, and 2100 fs for 85 {angstrom}, 130 {angstrom}, and 170 {angstrom} radius xenon clusters respectively. Model calculations suggest that these effects are due to resonant heating of the spherical plasma in agreement with the hydrodynamic interpretation of cluster interactions. While this simple hydrodynamic code produces reasonable agreement with data, it does not include bulk plasma or non-linear propagation effects and is limited to the regime where resonant behavior dominates. We also measured the scattered laser light from the laser-cluster interaction. Similar to the absorption measurements, there is an optimal pulse width which maximizes the scattered signal. This pulse width is larger than the optimal pulse width for absorption. This disagrees with model calculations which show both pulse widths being similar. Further experiments measuring the scattered light in a pump-probe configuration should help to resolve this disagreement.

  15. Direct observations of the atmospheric processing of Asian mineral dust

    NASA Astrophysics Data System (ADS)

    Sullivan, R. C.; Guazzotti, S. A.; Sodeman, D. A.; Prather, K. A.

    2007-02-01

    The accumulation of secondary acids and ammonium on individual mineral dust particles during ACE-Asia has been measured with an online single-particle mass spectrometer, the ATOFMS. Changes in the amounts of sulphate, nitrate, and chloride mixed with dust particles correlate with air masses from different source regions. The uptake of secondary acids depended on the individual dust particle mineralogy; high amounts of nitrate accumulated on calcium-rich dust while high amounts of sulphate accumulated on aluminosilicate-rich dust. Oxidation of S(IV) to S(VI) by iron in the aluminosilicate dust is a possible explanation for this enrichment of sulphate, which has important consequences for the fertilization of remote oceans by soluble iron. This study shows the segregation of sulphate from nitrate and chloride in individual aged dust particles for the first time. A transport and aging timeline provides an explanation for the observed segregation. Our data suggests that sulphate became mixed with the dust first. This implies that the transport pathway is more important than the reaction kinetics in determining which species accumulate on mineral dust. Early in the study, dust particles in volcanically influenced air masses were mixed predominately with sulphate. Dust mixed with chloride then dominated over sulphate and nitrate when a major dust front reached the R. V. Ronald Brown. We hypothesize that the rapid increase in chloride on dust was due to mixing with HCl(g) released from acidified sea salt particles induced by heterogeneous reaction with volcanic SO2(g), prior to the arrival of the dust front. The amount of ammonium mixed with dust correlated strongly with the total amount of secondary acid reaction products in the dust. Submicron dust and ammonium sulphate were internally mixed, contrary to frequent reports that they exist as external mixtures. The size distribution of the mixing state of dust with these secondary species validates previous mechanisms of

  16. Relation between Direct Observation of Relaxation and Self-Reported Mindfulness and Relaxation States

    ERIC Educational Resources Information Center

    Hites, Lacey S.; Lundervold, Duane A.

    2013-01-01

    Forty-four individuals, 18-47 (MN 21.8, SD 5.63) years of age, took part in a study examining the magnitude and direction of the relationship between self-report and direct observation measures of relaxation and mindfulness. The Behavioral Relaxation Scale (BRS), a valid direct observation measure of relaxation, was used to assess relaxed behavior…

  17. Observation of uniaxial anisotropy along the [100] direction in crystalline Fe film

    PubMed Central

    Bac, Seul-Ki; Lee, Hakjoon; Lee, Sangyoep; Choi, Seonghoon; Yoo, Taehee; Lee, Sanghoon; Liu, X.; Furdyna, J. K.

    2015-01-01

    We report an observation of uniaxial magnetic anisotropy along the [100] crystallographic direction in crystalline Fe film grown on Ge buffers deposited on a (001) GaAs substrate. As expected, planar Hall resistance (PHR) measurements reveal the presence of four in-plane magnetic easy axes, indicating the dominance of the cubic anisotropy in the film. However, systematic mapping of the PHR hysteresis loops observed during magnetization reversal at different field orientations shows that the easy axes along the and are not equivalent. Such breaking of the cubic symmetry can only be ascribed to the presence of uniaxial anisotropy along the direction of the Fe film. Analysis of the PHR data measured as a function of orientation of the applied magnetic field allowed us to quantify the magnitude of this uniaxial anisotropy field as Oe. Although this value is only 1.5% of cubic anisotropy field, its presence significantly changes the process of magnetization reversal, revealing the important role of the uniaxial anisotropy in Fe films. Breaking of the cubic symmetry in the Fe film deposited on a Ge buffer is surprising, and we discuss possible reason for this unexpected behavior. PMID:26635278

  18. Direct Time-Domain Observation of Conformational Relaxation in Gas-Phase Cold Collisions.

    PubMed

    Drayna, Garrett K; Hallas, Christian; Wang, Kenneth; Domingos, Sergio R; Eibenberger, Sandra; Doyle, John M; Patterson, David

    2016-04-11

    Cooling molecules in the gas phase is important for precision spectroscopy, cold molecule physics, and physical chemistry. Measurements of conformational relaxation cross sections shed important light on potential energy surfaces and energy flow within a molecule. However, gas-phase conformational cooling has not been previously observed directly. In this work, we directly observe conformational dynamics of 1,2-propanediol in cold (6 K) collisions with atomic helium using microwave spectroscopy and buffer-gas cooling. Precise knowledge and control of the collisional environment in the buffer-gas allows us to measure the absolute collision cross-section for conformational relaxation. Several conformers of 1,2-propanediol are investigated and found to have relaxation cross-sections with He ranging from σ=4.7(3.0)×10(-18)  cm(2) to σ>5×10(-16)  cm(2) . Our method is applicable to a broad class of molecules and could be used to provide information about the potential energy surfaces of previously uninvestigated molecules. PMID:26992036

  19. Development of a Direct Observation Instrument to Measure Environmental Characteristics of Parks for Physical Activity

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The study's purpose is to describe the development and evaluate the reliability (inter-observer agreement) and validity (rater agreement with a gold standard) of a direct observation instrument to assess park characteristics that may be related to physical activity. A direct observation instrument ...

  20. Estimating Percent of Time and Rate Via Direct Observation: A Suggested Observational Procedure and Format.

    ERIC Educational Resources Information Center

    Saudargas, Richard A.; Lentz, Frances E., Jr.

    1986-01-01

    Using development of a State Event Observation System as an example, the decision rules and procedures for the constructing of standardized multiple behavior observational systems that provide accurate, reliable data for school-based assessment, intervention, and research are described. Reliability and validity data from the SECOS are provided.…

  1. Combining direct and remote observations with modeling to understand the terrestrial carbon cycle

    NASA Astrophysics Data System (ADS)

    Churkina, G.

    2002-06-01

    Explaining observed regional-scale variability of carbon fluxes is critical for increasing the credibility of predictions of future ecosystem changes. Combining direct and remote observations is not straightforward because the observations are taken at different spatial and temporal scales and previous land satellite missions have not been designed for use together with existing measuring networks. Although ecosystem models, which estimate relevant components of the carbon cycle at different spatial and temporal scale, can serve as an integrative tool, their estimates of the state variables have uncertainties related to the poorly understood processes. Nevertheless, our first attempts to combine the three tools show interesting relationships between satellite indices and flux measurements as well as outline some issues, which can be resolve by the type of data provided by SPECTRA. A new technique of CO2 and energy fluxes measurements on tall (200-600 m) towers allows studying ecosystem-atmosphere interactions at the regional scale using a combination of CO2 observations, ecosystem modeling, and remote sensing. Signal measured at a tall tower integrates both daily biogeochemical cycles and small-scale heterogeneity of the land surface. For 1997-99 we compared the "preferred" annual net ecosystem exchange (NEE) measured at the tall tower in Wisconsin to the simulated annual NEE (BIOME-BGC model) and to adjusted normalized difference vegetation index (NDVI) aggregated over each year. Most of the differences between measured and modeled fluxes occurred in the beginning and the end of growing season. The length of the carbon uptake period defined by CO2 exchange observations was better captured by remote observations (NDVI) than by the model. Small deviations in growing season length resulted in significantly different annual NEE from measurements and model simulations. Analysis of the carbon uptake period by terrestrial vegetation and the annual net ecosystem exchange

  2. Direct Observation of Teacher-Directed IEP Meetings: Establishing the Need for Student IEP Meeting Instruction

    ERIC Educational Resources Information Center

    Martin, James E.; Van Dycke, Jamie L.; Greene, Barbara A.; Gardner, J. Emmett; Christensen, W. Robert; Woods, Lee L.; Lovett, David L.

    2006-01-01

    The 1997 reauthorization of the Individuals with Disabilities Education Act (IDEA) called for an increase in student involvement in individualized education program (IEP) meetings. To determine the extent of student involvement in educational planning, this study observed 109 middle and high school IEP meetings; 90% of the participants completed a…

  3. Direct and indirect inactivation of tumor cell protective catalase by salicylic acid and anthocyanidins reactivates intercellular ROS signaling and allows for synergistic effects.

    PubMed

    Scheit, Katrin; Bauer, Georg

    2015-03-01

    Salicylic acid and anthocyanidins are known as plant-derived antioxidants, but also can provoke paradoxically seeming prooxidant effects in vitro. These prooxidant effects are connected to the potential of salicylic acid and anthocyanidins to induce apoptosis selectively in tumor cells in vitro and to inhibit tumor growth in animal models. Several epidemiological studies have shown that salicylic acid and its prodrug acetylsalicylic acid are tumor-preventive for humans. The mechanism of salicylic acid- and anthocyanidin-dependent antitumor effects has remained enigmatic so far. Extracellular apoptosis-inducing reactive oxygen species signaling through the NO/peroxynitrite and the HOCl signaling pathway specifically induces apoptosis in transformed cells. Tumor cells have acquired resistance against intercellular reactive oxygen species signaling through expression of membrane-associated catalase. Here, we show that salicylic acid and anthocyanidins inactivate tumor cell protective catalase and thus reactive apoptosis-inducing intercellular reactive oxygen species signaling of tumor cells and the mitochondrial pathway of apoptosis Salicylic acid inhibits catalase directly through its potential to transform compound I of catalase into the inactive compound II. In contrast, anthocyanidins provoke a complex mechanism for catalase inactivation that is initiated by anthocyanidin-mediated inhibition of NO dioxygenase. This allows the formation of extracellular singlet oxygen through the reaction between H(2)O(2) and peroxynitrite, amplification through a caspase8-dependent step and subsequent singlet oxygen-mediated inactivation of catalase. The combination of salicylic acid and anthocyanidins allows for a remarkable synergistic effect in apoptosis induction. This effect may be potentially useful to elaborate novel therapeutic approaches and crucial for the interpretation of epidemiological results related to the antitumor effects of secondary plant compounds. PMID

  4. DIRECT OBSERVATION OF THE COOLING OF THE CASSIOPEIA A NEUTRON STAR

    SciTech Connect

    Heinke, Craig O.; Ho, Wynn C. G. E-mail: wynnho@slac.stanford.ed

    2010-08-20

    The cooling rate of young neutron stars (NSs) gives direct insight into their internal makeup. Although the temperatures of several young NSs have been measured, until now a young NS has never been observed to decrease in temperature over time. We fit nine years of archival Chandra ACIS spectra of the likely NS in the {approx}330 yr old Cassiopeia A supernova remnant with our non-magnetic carbon atmosphere model. Our fits show a relative decline in the surface temperature by 4% (5.4{sigma}, from (2.12 {+-} 0.01) x 10{sup 6} K in 2000 to (2.04 {+-} 0.01) x 10{sup 6} K in 2009) and the observed flux by 21%. Using a simple model for NS cooling, we show that this temperature decline could indicate that the NS became isothermal sometime between 1965 and 1980, and constrains some combinations of neutrino emission mechanisms and envelope compositions. However, the NS is likely to have become isothermal soon after formation, in which case the temperature history suggests episodes of additional heating or more rapid cooling. Observations over the next few years will allow us to test possible explanations for the temperature evolution.

  5. Direct Imaging of an Emerging Flux Rope and a Resulting Chromospheric Jet Observed by Hinode

    NASA Astrophysics Data System (ADS)

    Liu, Wei; Berger, T.; Title, A. M.; Tarbell, T. D.; DeRosa, M.

    2010-05-01

    Magnetic flux emergence has been traditionally observed on the disk by identifying changes in magnetograms. Observations near the limb offer an alternative perspective and allow direct imaging of emerging flux ropes. We present Hinode/SOT Ca II H observations of such an event in an equatorial coronal hole on 2007 February 9. The precursor of the event was a bundle of fine material threads that extended at an oblique angle above the chromosphere and appeared to rotate about a common axis. This bundle first slowly and then rapidly swung up, accompanied by a loop that appeared at the base of the bundle and expanded at comparable rates. During the first (slow rise) stage, the apex of the loop ascended at 16 km/s, a velocity similar to that of H-alpha arch filaments (e.g., Chou & Zirin) and of emerging flux ropes expanding into the corona as found in MHD simulations (e.g., Fan & Gibson; Martinez-Sykora). The second stage started at the onset of a GOES A5 flare and the loop expansion accelerated, reaching a velocity of 130 km/s when the loop appeared to rupture near the peak of the flare. The material bundle then swung back in a whiplike manner and developed into a collimated jet, exhibiting oscillatory transverse motions across its axis, as expected from unwinding twists. Some jet material fell back along smooth streamlines, which bypass an unseen dome and presumably a null point in the low corona, depicting an inverted-Y shape. Some of these observations resemble the model (e.g., Uchida & Shibata) of the emergence of a twisted flux rope into an open field region that leads to reconnection and formation of a jet. Some observations are, however, not predicted in previous models and we will discuss their implications.

  6. Validation of a New Counter for Direct Observation of Physical Activity in Parks

    PubMed Central

    Han, Bing; Cohen, Deborah A.; Derose, Kathryn Pitkin; Marsh, Terry; Williamson, Stephanie; Raaen, Laura

    2015-01-01

    Purpose Prior tools to observe large groups of people in parks have not allowed disaggregation of physical activity levels by age group and gender simultaneously, making it impossible to determine which subgroups engaged in moderate to vigorous physical activity (MVPA). This study aims to examine the reliability of a 12-button counter to simultaneously assess MVPA by age and gender subgroups in park settings. Methods A total of 1,160 pairs of observations were conducted in 481 target areas of 19 neighborhood parks in the great Los Angeles area between June 2013 and March 2014. Inter-rater reliability was assessed by Pearson’s correlation, intra-class correlation (ICC), and agreement probability in the total metabolic equivalents (METs) and METs spent in MVPA. Cosine similarity was used to check the resemblance of distributions among age and gender categories. Pictures taken in a total of 112 target areas at the beginning of the observations were used as a second check on the reliability of direct observation. Results Inter-rater reliability was high for the total METs and METs in all age and gender categories (between 0.82 and 0.97), except for male seniors (correlations and ICC between 0.64 and 0.77, agreement probability 0.85 to 0.86). Reliability was higher for total METs than for METs spent in MVPA. Correlation and ICC between observers’ measurement and picture-based counts are also high (between 0.79 and 0.94). Conclusion Trained observers can reliably use the 12-button counter to accurately assess PA distribution and disparities by age and gender. PMID:26103584

  7. FISH and DAPI staining of the synaptonemal complex of the Nile tilapia (Oreochromis niloticus) allow orientation of the unpaired region of bivalent 1 observed during early pachytene.

    PubMed

    Ocalewicz, Konrad; Mota-Velasco, Jose C; Campos-Ramos, Rafael; Penman, David J

    2009-01-01

    Bivalent 1 of the synaptonemal complex (SC) in XY male Oreochromis niloticus shows an unpaired terminal region in early pachytene. This appears to be related to recombination suppression around a sex determination locus. To allow more detailed analysis of this, and unpaired regions in the karyotype of other Oreochromis species, we developed techniques for FISH on SC preparations, combined with DAPI staining. DAPI staining identified presumptive centromeres in SC bivalents, which appeared to correspond to the positions observed in the mitotic karyotype (the kinetochores could be identified only sporadically in silver-stained EM SC images). Furthermore, two BAC clones containing Dmo (dmrt4) and OniY227 markers that hybridize to known positions in chromosome pair 1 in mitotic spreads (near the centromere, Flpter 0.25, and the putative sex-determination locus, Flpter 0.57, respectively) were used as FISH probes on SCs to verify that the presumptive centromere identified by DAPI staining was located in the expected position. Visualization of both the centromere and FISH signals on bivalent 1 allowed the unpaired region to be positioned at Flpter 0.80 to 1.00, demonstrating that the unpaired region is located in the distal part of the long arm(s). Finally, differences between mitotic and meiotic measurements are discussed. PMID:19714475

  8. Direct Observation of Virtual Electrode Formation Through a Novel Electrolyte-to-Electrode Transition

    NASA Astrophysics Data System (ADS)

    Siegel, David; El Gabaly, Farid; Bartelt, Norman; McCarty, Kevin

    2014-03-01

    Novel electrochemical solutions to problems in energy storage and transportation can drive renewable energy to become an economically viable alternative to fossil fuels. In many electrochemical systems, the behavior of a device can be fundamentally limited by the surface area of a triple phase boundary, the boundary region where a gas-phase species, electrode, and electrolyte coincide. When the electrode is an ionic insulator the triple phase boundary is typically a one-dimensional boundary with nanometer-scale thickness: ions cannot transport through the electrode, while electrons cannot be transported through the electrolyte. Here we present direct experimental measurements of a novel electrolyte-to-electrode transition with photoemission electron microscopy, and observe that the surface of an ionically conductive, electronically insulative solid oxide electrolyte undergoes a transition into a mixed electron-ion conductor in the vicinity of a metal electrode. Our direct experimental measurements allow us to characterize this system and address the mechanisms of ionic reactions and transport through comparisons with theoretical modeling to provide us with a physical picture of the processes involved. Our results provide insight into one of the mechanisms of ion transport in an electrochemical cell that may be generalizable to other systems.

  9. Directional Surface Plasmon Coupled Luminescence for Analytical Sensing Applications: Which Metal, What Wavelength, What Observation Angle?

    PubMed Central

    Aslan, Kadir; Geddes, Chris D.

    2009-01-01

    The ability of luminescent species in the near-field to both induce and couple to surface plasmons has been known for many years, with highly directional emission from films (Surface Plasmon Coupled Luminescence, SPCL) facilitating the development of sensitive near-field assay sensing platforms, to name but just one application. Because of the near-field nature of the effect, only luminescent species (fluorescence, chemiluminescence and phosphorescence) within a few hundred nanometers from the surface play a role in coupling, which in terms of biosensing, provides for limited penetration into optically dense media, such as in whole blood. Another attractive feature is the highly polarized and angular dependent emission which allows both fixed angle and wavelength dependent emission angles to be realized at high polarization ratios. In this paper, a generic procedure based on theoretical Fresnel calculations, which outlines the step-by-step selection of an appropriate metal for SPCL applications is presented. It is also shown that 11 different metals have differing properties in different spectral regions and offer either fixed angle or wavelength-dependent angular shifts in emission. In addition, it is shown that both chemiluminescence and phosphorescence can also be observed in a highly directional manner similar to coupled fluorescence. PMID:19601619

  10. 10 CFR 26.115 - Collecting a urine specimen under direct observation.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 10 Energy 1 2013-01-01 2013-01-01 false Collecting a urine specimen under direct observation. 26.115 Section 26.115 Energy NUCLEAR REGULATORY COMMISSION FITNESS FOR DUTY PROGRAMS Collecting Specimens for Testing § 26.115 Collecting a urine specimen under direct observation. (a) Procedures...

  11. 10 CFR 26.115 - Collecting a urine specimen under direct observation.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 10 Energy 1 2014-01-01 2014-01-01 false Collecting a urine specimen under direct observation. 26.115 Section 26.115 Energy NUCLEAR REGULATORY COMMISSION FITNESS FOR DUTY PROGRAMS Collecting Specimens for Testing § 26.115 Collecting a urine specimen under direct observation. (a) Procedures...

  12. 10 CFR 26.115 - Collecting a urine specimen under direct observation.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 10 Energy 1 2011-01-01 2011-01-01 false Collecting a urine specimen under direct observation. 26.115 Section 26.115 Energy NUCLEAR REGULATORY COMMISSION FITNESS FOR DUTY PROGRAMS Collecting Specimens for Testing § 26.115 Collecting a urine specimen under direct observation. (a) Procedures...

  13. 10 CFR 26.115 - Collecting a urine specimen under direct observation.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 10 Energy 1 2010-01-01 2010-01-01 false Collecting a urine specimen under direct observation. 26.115 Section 26.115 Energy NUCLEAR REGULATORY COMMISSION FITNESS FOR DUTY PROGRAMS Collecting Specimens for Testing § 26.115 Collecting a urine specimen under direct observation. (a) Procedures...

  14. 10 CFR 26.115 - Collecting a urine specimen under direct observation.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 10 Energy 1 2012-01-01 2012-01-01 false Collecting a urine specimen under direct observation. 26.115 Section 26.115 Energy NUCLEAR REGULATORY COMMISSION FITNESS FOR DUTY PROGRAMS Collecting Specimens for Testing § 26.115 Collecting a urine specimen under direct observation. (a) Procedures...

  15. Direct Observations of Clouds on Brown Dwarfs: A Spitzer Study of Extreme Cases

    NASA Astrophysics Data System (ADS)

    Burgasser, Adam; Cruz, Kelle; Cushing, Michael; Kirkpatrick, J. Davy; Looper, Dagny; Lowrance, Patrick; Marley, Mark; Saumon, Didier

    2008-03-01

    Clouds play a fundamental role in the emergent spectral energy distributions and observed variability of very low mass stars and brown dwarfs, yet hey have only been studied indirectly thus far. Recent indications of a broad silicate grain absorption feature in the 8-11 micron spectra of mid-type L dwarfs, and evidence that the strength of this absorption varies according to broad-band near-infrared color, may finally allow the first direct studies of clouds and condensate grain properties in brown dwarf atmospheres. We propose to observe a sample of 18 ``extreme'' L dwarfs - objects with unusually blue and red near-infrared colors - with IRAC and IRS to study the 8-11 micron feature in detail (including grain size distributions and bulk compositions), and to constrain advanced condensate cloud atmosphere models currently in development. Our program provides a unique examination of the general processes of cloud formation by focusing on the relatively warm photospheres of late-type brown dwarfs.

  16. Mid-depth recirculation observed in the interior Labrador and Irminger seas by direct velocity measurements

    PubMed

    Lavender; Davis; Owens

    2000-09-01

    The Labrador Sea is one of the sites where convection exports surface water to the deep ocean in winter as part of the thermohaline circulation. Labrador Sea water is characteristically cold and fresh, and it can be traced at intermediate depths (500-2,000 m) across the North Atlantic Ocean, to the south and to the east of the Labrador Sea. Widespread observations of the ocean currents that lead to this distribution of Labrador Sea water have, however, been difficult and therefore scarce. We have used more than 200 subsurface floats to measure directly basin-wide horizontal velocities at various depths in the Labrador and Irminger seas. We observe unanticipated recirculations of the mid-depth (approximately 700 m) cyclonic boundary currents in both basins, leading to an anticyclonic flow in the interior of the Labrador basin. About 40% of the floats from the region of deep convection left the basin within one year and were rapidly transported in the anticyclonic flow to the Irminger basin, and also eastwards into the subpolar gyre. Surprisingly, the float tracks did not clearly depict the deep western boundary current, which is the expected main pathway of Labrador Sea water in the thermohaline circulation. Rather, the flow along the boundary near Flemish Cap is dominated by eddies that transport water offshore. Our detailed observations of the velocity structure with a high data coverage suggest that we may have to revise our picture of the formation and spreading of Labrador Sea water, and future studies with similar instrumentation will allow new insights on the intermediate depth ocean circulation. PMID:10993072

  17. Wide-field direct CCD observations supporting the Astro-1 Space Shuttle mission's Ultraviolet Imaging Telescope

    NASA Technical Reports Server (NTRS)

    Hintzen, Paul; Angione, Ron; Talbert, Freddie; Cheng, K.-P.; Smith, Eric; Stecher, Theodore P.

    1993-01-01

    Wide field direct CCD observations are being obtained to support and complement the vacuum-ultraviolet (VUV) images provided by Astro's Ultraviolet Imaging Telescope (UIT) during a Space Shuttle flight in December 1990. Because of the wide variety of projects addressed by UIT, the fields observed include (1) galactic supernova remnants such as the Cygnus Loop and globular clusters such as Omega Cen and M79; (2) the Magellanic Clouds, M33, M81, and other galaxies in the Local Group; and (3) rich clusters of galaxies, principally the Perseus cluster and Abell 1367. Ground-based observations have been obtained for virtually all of the Astro-1 UIT fields. The optical images allow identification of individual UV sources in each field and provide the long baseline in wavelength necessary for accurate analysis of UV-bright sources. To facilitate use of our optical images for analysis of UIT data and other projects, we plan to archive them, with the UIT images, at the National Space Science Data Center (NSSDC), where they will be universally accessible via anonymous FTP. The UIT, one of three telescopes comprising the Astro spacecraft, is a 38-cm f/9 Ritchey-Chretien telescope on which high quantum efficiency, solar-blind image tubes are used to record VUV images on photographic film. Five filters with passbands centered between 1250A and 2500A provide both VUV colors and a measurement of extinction via the 2200A dust feature. The resulting calibrated VUV pictures are 40 arcminutes in diameter at 2.5 arcseconds resolution. The capabilities of UIT, therefore, complement HST's WFPC: the latter has 40 times greater collecting area, while UIT's usable field has 170 times WFPC's field area.

  18. Direct retrieval of ocean surface evaporation and latent heat flux from the spacebased observations

    NASA Technical Reports Server (NTRS)

    Liu, W. T.; Tang, W.

    2000-01-01

    The Tropical Rain Measuring Mission (TRMM) provides the opportunity to improve the spacebased estimation of evaporation. An algorithm for retrieving evaporation directly from the radiances observed by the TRMM Microwave Imager and its validation results are described.

  19. Direct Observation of Three-dimensional Electroconvective Vortices on a Charge Selective Surface

    NASA Astrophysics Data System (ADS)

    Kwak, Rhokyun; Han, Jongyoon; Lee, Taikjin; Kwak, Ho-Young

    2015-11-01

    We present a visualization of three-dimensional electroconvective vortices (EC) by ion concentration polarization (ICP) on a cation selective membrane. The vortices are initiated between two transparent Nafion membranes under no-shear/shear conditions with various applied voltages and flow velocities. Fluorescent imaging and spatial Fourier transform allow us to capture vortex structures. In this 3-D system, EC shows three distinguished structures: i) polygonal shapes with no-shear and ii) transverse and/or iii) longitudinal vortex rolls with shear flow, which is reminiscent of 3-D Rayleigh-Benard instability. Under shear flow, as flow velocity (Reynolds number: Re) increases or voltage (electric Rayleigh number: Ra) decreases, pure longitudinal vortices are presented; in the inverse case, transverse vortices are also formed. It is noteworthy that if we confine EC in quasi 2-D system with high Ra (>10,000), we obtain pure transverse vortices; high Ra induces chaotic EC in this 3-D system, instead of 2-D stable transverse vortices. To the best of our knowledge, this is the first direct observation of 3-D EC, which will occur in realistic electrochemical devices, e.g. electrodialysis.

  20. Excitable dendrites and spines: earlier theoretical insights elucidate recent direct observations.

    PubMed

    Segev, I; Rall, W

    1998-11-01

    Important advances in experimental methods have made it possible to measure the electrical events in dendrites directly and to record optically from dendritic spines. These new techniques allow us to focus on the input region of the neuron and highlight the excitable properties of the dendritic membrane. Interestingly, some of the recent experimental findings were anticipated by earlier theoretical research, for example, the observation that some spines possess excitable channels that might generate local all-or-none events. Computer models were used previously to explore the conditions for initiating an action potential at the dendritic tree, in particular, at the spine head, and for active propagation between excitable spines and excitable dendritic arbors. The consequences for synaptic amplification, for the extent of active spread in the tree and for non-linear discriminations between different patterns of synaptic inputs were also considered. Here we review the biophysical insights gained from the theory and demonstrate how these elucidate the recent experimental results. PMID:9829684

  1. Direct Observation of the Intrinsic Backbone Torsional Mobility of Disordered Proteins.

    PubMed

    Jain, Neha; Narang, Dominic; Bhasne, Karishma; Dalal, Vijit; Arya, Shruti; Bhattacharya, Mily; Mukhopadhyay, Samrat

    2016-08-23

    The fundamental backbone dynamics of unfolded proteins arising due to intrinsic ϕ-ψ dihedral angle fluctuations dictate the course of protein folding, binding, assembly, and function. These internal fluctuations are also critical for protein misfolding associated with a range of human diseases. However, direct observation and unambiguous assignment of this inherent dynamics in chemically denatured proteins is extremely challenging due to various experimental limitations. To directly map the backbone torsional mobility in the ϕ-ψ dihedral angle space, we used a model intrinsically disordered protein, namely, α-synuclein, that adopts an expanded state under native conditions. We took advantage of nonoccurrence of tryptophan in α-synuclein and created a number of single-tryptophan variants encompassing the entire polypeptide chain. We then utilized highly sensitive picosecond time-resolved fluorescence depolarization measurements that allowed us to discern the site-specific torsional relaxation at a low protein concentration under physiological conditions. For all the locations, the depolarization kinetics exhibited two well-separated rotational-correlation-time components. The shorter, subnanosecond component arises due to the local mobility of the indole side chain, whereas the longer rotational-correlation-time component (1.37 ± 0.15 ns), independent of global tumbling, represents a characteristic timescale for short-range conformational exchange in the ϕ-ψ dihedral space. This correlation time represents an intrinsic timescale for torsional relaxation and is independent of position, which is expected for an extended polypeptide chain having little or no propensity to form persistent structures. We were also able to capture this intrinsic timescale at the N-terminal unstructured domain of the prion protein. Our estimated timescale of the segmental mobility is similar to that of unfolded proteins studied by nuclear magnetic resonance in conjunction with

  2. Direct observation of roaming radicals in the thermal decomposition of acetaldehyde.

    SciTech Connect

    Sivaramakrishnan, R.; Michael, J. V.; Klippenstein, S. J.; Chemical Sciences and Engineering Division

    2010-01-21

    The thermal dissociation of acetaldehyde has been studied with the reflected shock tube technique using H(D)-atom atomic resonance absorption spectrometry detection. The use of an unreversed light source yields extraordinarily sensitive H atom detection. As a result, we are able to measure both the total decomposition rate and the branching to radical versus molecular channels. This branching provides a direct measure of the contribution from the roaming radical mechanism since the contributions from the usual tight transition states are predicted by theory to be negligible. The experimental observations also provide a measure of the rate coefficient for H + CH{sub 3}CHO. Another set of experiments employing C{sub 2}H{sub 5}I as an H-atom source provides additional data for this rate coefficient that extends to lower temperature. An evaluation of the available experimental results for H + CH{sub 3}CHO can be expressed by a three-parameter Arrhenius expression as k = 7.66 x 10{sup -20}T{sup 2.75} exp((-486 K)/T) cm{sup 3} molecule{sup -1} s{sup -1} (298-1415 K). Analogous experiments employing C{sub 2}D{sub 5}I as a D-atom source allow for the study of the isotopically substituted reaction. The present experiments are the only direct measure for this reaction rate constant, and the results can be expressed by an Arrhenius expression as k = 5.20 x 10{sup -10} exp((-4430 K)/T) cm{sup 3} molecule{sup -1} s{sup -1} (1151-1354 K). The H/D + CH{sub 3}CHO reactions are also studied with ab initio transition-state theory, and the results are in remarkably good agreement with the current experimental data.

  3. Rationale and design of a randomized controlled trial of varenicline directly observed therapy delivered in methadone clinics

    PubMed Central

    2014-01-01

    Background Tobacco cessation medication adherence is one of the few factors shown to improve smoking cessation rates among methadone-maintained smokers, but interventions to improve adherence to smoking cessation medications have not yet been tested among methadone treatment patients. Methadone clinic-based, directly observed therapy (DOT) programs for HIV and tuberculosis improve adherence and clinical outcomes, but have not been evaluated for smoking cessation. We describe a randomized controlled trial to evaluate whether a methadone clinic-based, directly observed varenicline therapy program increases adherence and tobacco abstinence among opioid-dependent drug users receiving methadone treatment. Methods/Design We plan to enroll 100 methadone-maintained smokers and randomize them to directly observed varenicline dispensed with daily methadone doses or treatment as usual (self-administered varenicline) for 12 weeks. Our outcome measures are: 1) pill count adherence and 2) carbon monoxide-verified tobacco abstinence. We will assess differences in adherence and abstinence between the two treatment arms using repeated measures models. Discussion This trial will allow for rigorous evaluation of the efficacy of methadone clinic-based, directly observed varenicline for improving adherence and smoking cessation outcomes. This detailed description of trial methodology can serve as a template for the development of future DOT programs and can guide protocols for studies among opioid-dependent smokers receiving methadone treatment. Trial Registration clinicaltrials.gov NCT01378858 PMID:24928218

  4. Direct observation of electron propagation and dielectric screening on the atomic length scale.

    PubMed

    Neppl, S; Ernstorfer, R; Cavalieri, A L; Lemell, C; Wachter, G; Magerl, E; Bothschafter, E M; Jobst, M; Hofstetter, M; Kleineberg, U; Barth, J V; Menzel, D; Burgdörfer, J; Feulner, P; Krausz, F; Kienberger, R

    2015-01-15

    The propagation and transport of electrons in crystals is a fundamental process pertaining to the functioning of most electronic devices. Microscopic theories describe this phenomenon as being based on the motion of Bloch wave packets. These wave packets are superpositions of individual Bloch states with the group velocity determined by the dispersion of the electronic band structure near the central wavevector in momentum space. This concept has been verified experimentally in artificial superlattices by the observation of Bloch oscillations--periodic oscillations of electrons in real and momentum space. Here we present a direct observation of electron wave packet motion in a real-space and real-time experiment, on length and time scales shorter than the Bloch oscillation amplitude and period. We show that attosecond metrology (1 as = 10(-18) seconds) now enables quantitative insight into weakly disturbed electron wave packet propagation on the atomic length scale without being hampered by scattering effects, which inevitably occur over macroscopic propagation length scales. We use sub-femtosecond (less than 10(-15) seconds) extreme-ultraviolet light pulses to launch photoelectron wave packets inside a tungsten crystal that is covered by magnesium films of varied, well-defined thicknesses of a few ångströms. Probing the moment of arrival of the wave packets at the surface with attosecond precision reveals free-electron-like, ballistic propagation behaviour inside the magnesium adlayer--constituting the semi-classical limit of Bloch wave packet motion. Real-time access to electron transport through atomic layers and interfaces promises unprecedented insight into phenomena that may enable the scaling of electronic and photonic circuits to atomic dimensions. In addition, this experiment allows us to determine the penetration depth of electrical fields at optical frequencies at solid interfaces on the atomic scale. PMID:25592539

  5. Simultaneous Measurements of direct, semi-direct and indirect aerosol forcing with Stacked Autonomous UAVs: A New Observing Platform

    NASA Astrophysics Data System (ADS)

    Ramanathan, V.; Roberts, G.; Ramana, M. V.; Corrigan, C.; Nguyen, H.

    2006-12-01

    We report here first time demonstration with three autonomously flying Unmanned Aerial Vehicles (UAVs) of cloudy sky albedo, transmission atmospheric solar absorption, aerosol and cloud droplet concentrations and number densities. From these direct measurements we derive the direct, semi-direct and the first indirect aerosol forcing. The observing system consisted of 3 light weight UAVs, instrumented with miniaturized instruments (Roberts et al, 2006; Ramana et al, 2006; Corrigan et al 2006) for measuring aerosol concentrations and size distribution, cloud microphysical properties, black carbon concentration and broad band and narrow band solar fluxes. The airborne measurements were validated and augmented by the Atmospheric Brown Clouds Maldives Climate Observatory (ABC_MCO) in the island of Hanimaadhoo in the N. Indian Ocean (Corrigan et al, 2006; Ramana and Ramanathan 2006). The campaign was conducted during March and early April of 2006 when this region is subject to long range transport of pollution from S. Asia. In the stacked 3_UAV configuration, one flew in the boundary layer below clouds to characterize the aerosols feeding the clouds and the transmission of solar radiation by the absorbing aerosol layer and clouds above; the second inside the trade cumulus clouds to directly observe the fully nucleated cloud drop size and concentrations and total liquid water content; and the third above the cloud to determine the incoming solar and the reflected solar radiation. The 3-UAVs were programmed to sample the same region(or clouds) within seconds of each other, thus providing unique insights into how aerosols and boundary layer dynamics modulate the cloud microphysics and thus the albedo and solar absorption of cloudy skies in the planet. The period of observations also included a major dust-soot event which revealed a large increase in atmospheric solar absorption. We will present results on how 3- dimensional clouds with absorbing aerosols modulate

  6. The Stochastic Engine Initiative: Improving Prediction of Behavior in Geologic Environments We Cannot Directly Observe

    SciTech Connect

    Aines, R; Nitao, J; Newmark, R; Carle, S; Ramirez, A; Harris, D; Johnson, J; Johnson, V; Ermak, D; Sugiyama, G; Hanley, W; Sengupta, S; Daily, W; Glaser, R; Dyer, K; Fogg, G; Zhang, Y; Yu, Z; Levine, R

    2002-05-09

    , and most importantly an ability to obtain disparate data sets that are directly affected by the system configuration. Our initial earth-sciences application uses models for lithology, flow and transport, geochemistry, and geophysical imaging; the system configuration (base representation) being refined is the rock type at each underground location. In the initial stages of this initiative we demonstrated a two-stage analysis of synthetic Electrical Resistance Tomography (ERT) data and hydraulic flow information (Newmark et al., 2002). We used these results to develop algorithms that improve efficiency of the Metropolis search and provide accurate diagnostic evaluation during the search. Using actual data from a highly contaminated A/M outfall and solvent tank storage areas at the Savannah River Site (SRS), we used the stochastic engine to resolve lithology using ERT data. SRS will use these methods in their design and implementation of steam cleanup of the largest trichloroethylene (TCE) source in the Department of Energy (DOE) complex. We have implemented ''soft conditioning'' algorithms that allow us to use a variety of data types to control the initial representations, and most importantly, to use the final distribution resulting from one stochastic engine analysis as the initial distribution for a subsequent analysis. We have created a web-based interface that will allow collaborators like SRS to enter data and observe results of calculations on Lawrence Livermore National Laboratory (LLNL) supercomputers in an interactive mode. All engine functions operate in three dimensions, and a parallel implementation on Linux cluster machines is in initial testing. The method will be extended to include active process analysis, in which an ongoing data stream is used to continuously update the understanding of the system configuration. Applications to other types of state spaces, such as chemical parameters in a reacting system or atmospheric plume movement, are being

  7. Objectively Optimized Observation Direction System Providing Situational Awareness for a Sensor Web

    NASA Astrophysics Data System (ADS)

    Aulov, O.; Lary, D. J.

    2010-12-01

    There is great utility in having a flexible and automated objective observation direction system for the decadal survey missions and beyond. Such a system allows us to optimize the observations made by suite of sensors to address specific goals from long term monitoring to rapid response. We have developed such a prototype using a network of communicating software elements to control a heterogeneous network of sensor systems, which can have multiple modes and flexible viewing geometries. Our system makes sensor systems intelligent and situationally aware. Together they form a sensor web of multiple sensors working together and capable of automated target selection, i.e. the sensors “know” where they are, what they are able to observe, what targets and with what priorities they should observe. This system is implemented in three components. The first component is a Sensor Web simulator. The Sensor Web simulator describes the capabilities and locations of each sensor as a function of time, whether they are orbital, sub-orbital, or ground based. The simulator has been implemented using AGIs Satellite Tool Kit (STK). STK makes it easy to analyze and visualize optimal solutions for complex space scenarios, and perform complex analysis of land, sea, air, space assets, and shares results in one integrated solution. The second component is target scheduler that was implemented with STK Scheduler. STK Scheduler is powered by a scheduling engine that finds better solutions in a shorter amount of time than traditional heuristic algorithms. The global search algorithm within this engine is based on neural network technology that is capable of finding solutions to larger and more complex problems and maximizing the value of limited resources. The third component is a modeling and data assimilation system. It provides situational awareness by supplying the time evolution of uncertainty and information content metrics that are used to tell us what we need to observe and the

  8. Photographic observation of magnetic domain structure with three-dimensional local magnetization direction

    NASA Astrophysics Data System (ADS)

    Meguro, Sakae; Akahane, Koichi; Saito, Shin

    2016-07-01

    The direction of magnetization of a magnetic material is possibly oriented three-dimensionally because of the presence of magnetic anisotropy field, self-demagnetizing field, and stray field. Therefore, the three-dimensional detection of the direction of magnetization is required. The method of magnetic domain observation by photographic imaging utilizing the Kerr effect is widely used. If the perpendicular magnetization components exist, there is a problem that obliquely incident light has superimposed longitudinal Kerr and polar Kerr effects. To perform the three-dimensional detection of magnetization direction, it is necessary to eliminate the influence of the polar Kerr effect from the Kerr effect of obliquely incident light. We report the photographic observation of the magnetic domain structure and the detection of the three-dimensional local magnetization direction using the Kerr effect, applying only an in-plane saturation magnetic field.

  9. Unimolecular thermal decomposition of phenol and d5-phenol: Direct observation of cyclopentadiene formation via cyclohexadienone

    NASA Astrophysics Data System (ADS)

    Scheer, Adam M.; Mukarakate, Calvin; Robichaud, David J.; Nimlos, Mark R.; Carstensen, Hans-Heinrich; Barney Ellison, G.

    2012-01-01

    The pyrolyses of phenol and d5-phenol (C6H5OH and C6D5OH) have been studied using a high temperature, microtubular (μtubular) SiC reactor. Product detection is via both photon ionization (10.487 eV) time-of-flight mass spectrometry and matrix isolation infrared spectroscopy. Gas exiting the heated reactor (375 K-1575 K) is subject to a free expansion after a residence time in the μtubular reactor of approximately 50-100 μs. The expansion from the reactor into vacuum rapidly cools the gas mixture and allows the detection of radicals and other highly reactive intermediates. We find that the initial decomposition steps at the onset of phenol pyrolysis are enol/keto tautomerization to form cyclohexadienone followed by decarbonylation to produce cyclopentadiene; C6H5OH → c-C6H6 = O → c-C5H6 + CO. The cyclopentadiene loses a H atom to generate the cyclopentadienyl radical which further decomposes to acetylene and propargyl radical; c-C5H6 → c-C5H5 + H → HC≡CH + HCCCH2. At higher temperatures, hydrogen loss from the PhO-H group to form phenoxy radical followed by CO ejection to generate the cyclopentadienyl radical likely contributes to the product distribution; C6H5O-H → C6H5O + H → c-C5H5 + CO. The direct decarbonylation reaction remains an important channel in the thermal decomposition mechanisms of the dihydroxybenzenes. Both catechol (o-HO-C6H4-OH) and hydroquinone (p-HO-C6H4-OH) are shown to undergo decarbonylation at the onset of pyrolysis to form hydroxycyclopentadiene. In the case of catechol, we observe that water loss is also an important decomposition channel at the onset of pyrolysis.

  10. Direct observation of molecularly-aligned molecules in the second physisorbed layer-CO/Ag(110)

    SciTech Connect

    Lee, J.-G.; Hong, S.-H.; Ahner, J.; Zhao, X.; Chen, L.; Johnson, J.K.; Yates, J.T., Jr.

    2006-01-25

    We report the direct observation of oriented second-layer physisorbed molecules on a single crystal surface by electron stimulated desorption. Experiments and simulations show that the orientation of the second-layer physisorbed CO molecules on Ag(110) is the result of both electrostatic and dispersion forces from the underlying chemisorbed CO and Ag atoms. At 25 K, the physisorbed C-O bond is tilted and azimuthally oriented with the C-O bond axis inclined in an azimuthal plane at 45° to the principal Ag( 110) azimuthal crystallographic directions. The O atom in CO is directed outward, giving an O+ beam at 43° to the normal.

  11. Direct observation of grain growth from molten silicon formed by micro-thermal-plasma-jet irradiation

    PubMed Central

    Hayashi, Shohei; Fujita, Yuji; Kamikura, Takahiro; Sakaike, Kohei; Akazawa, Muneki; Ikeda, Mitsuhisa; Hanafusa, Hiroaki; Higashi, Seiichiro

    2012-01-01

    Phase transformation of amorphous-silicon during millisecond annealing using micro-thermal-plasma-jet irradiation was directly observed using a high-speed camera with microsecond time resolution. An oval-shaped molten-silicon region adjacent to the solid phase crystallization region was clearly observed, followed by lateral large grain growth perpendicular to a liquid-solid interface. Furthermore, leading wave crystallization (LWC), which showed intermittent explosive crystallization, was discovered in front of the moving molten region. The growth mechanism of LWC has been investigated on the basis of numerical simulation implementing explosive movement of a thin liquid layer driven by released latent heat diffusion in a lateral direction. PMID:23185095

  12. Directional surface plasmon coupled chemiluminescence from nickel thin films: Fixed angle observation

    NASA Astrophysics Data System (ADS)

    Weisenberg, Micah; Aslan, Kadir; Hortle, Elinor; Geddes, Chris D.

    2009-04-01

    Directional surface plasmon coupled chemiluminescence (SPCC) from nickel thin films is demonstrated. Free-space and angular-dependent SPCC emission from blue, green and turquoise chemiluminescent solutions placed onto nickel thin films attached to a hemispherical prism were measured. SPCC emission was found to be highly directional and preferentially p-polarized, in contrast to the unpolarized and isotropic chemiluminescence emission. The largest SPCC emission for all chemiluminescence solutions was observed at a fixed observation angle of 60°, which was also predicted by theoretical Fresnel calculations. It was found that nickel thin films did not have a catalytic effect on chemiluminescence emission.

  13. In vivo micro-computed tomography allows direct three-dimensional quantification of both bone formation and bone resorption parameters using time-lapsed imaging.

    PubMed

    Schulte, Friederike A; Lambers, Floor M; Kuhn, Gisela; Müller, Ralph

    2011-03-01

    Bone is a living tissue able to adapt its structure to external influences such as altered mechanical loading. This adaptation process is governed by two distinct cell types: bone-forming cells called osteoblasts and bone-resorbing cells called osteoclasts. It is therefore of particular interest to have quantitative access to the outcomes of bone formation and resorption separately. This article presents a non-invasive three-dimensional technique to directly extract bone formation and resorption parameters from time-lapsed in vivo micro-computed tomography scans. This includes parameters such as Mineralizing Surface (MS), Mineral Apposition Rate (MAR), and Bone Formation Rate (BFR), which were defined in accordance to the current nomenclature of dynamic histomorphometry. Due to the time-lapsed and non-destructive nature of in vivo micro-computed tomography, not only formation but also resorption can now be assessed quantitatively and time-dependent parameters Eroded Surface (ES) as well as newly defined indices Mineral Resorption Rate (MRR) and Bone Resorption Rate (BRR) are introduced. For validation purposes, dynamic formation parameters were compared to the traditional quantitative measures of dynamic histomorphometry, where MAR correlated with R = 0.68 and MS with R = 0.78 (p < 0.05). Reproducibility was assessed in 8 samples that were scanned 5 times and errors ranged from 0.9% (MRR) to 6.6% (BRR). Furthermore, the new parameters were applied to a murine in vivo loading model. A comparison of directly extracted parameters between formation and resorption within each animal revealed that in the control group, i.e., during normal remodeling, MAR was significantly lower than MRR (p < 0.01), whereas MS compared to ES was significantly higher (p < 0.0001). This implies that normal remodeling seems to take place by many small formation packets and few but large resorption volumes. After 4 weeks of mechanical loading, newly extracted trabecular BFR and MS were

  14. Observation of trichomonads infection in a child with periodontitis by direct microscopy at the dental office.

    PubMed

    Marty, Mathieu; Bonner, Mark; Vaysse, Frédéric

    2015-09-01

    The pathogenicity of Trichomonas species is well documented. Although their exact involvement in gum disease is not fully understood, recent studies suggest a correlation between these protozoa and periodontitis. This case report details the first chair-side observation in Europe of an oral trichomonad infection in a child with periodontitis, by direct microscopy. The dramatic recovery of the patient, observed following administration of an anti-parasitic treatment, confirms the necessity of further investigation in this field. PMID:26169391

  15. Observing Grasping Actions Directed to Emotion-Laden Objects: Effects upon Corticospinal Excitability

    PubMed Central

    Nogueira-Campos, Anaelli A.; Saunier, Ghislain; Della-Maggiore, Valeria; De Oliveira, Laura A. S.; Rodrigues, Erika C.; Vargas, Claudia D.

    2016-01-01

    The motor system is recruited whenever one executes an action as well as when one observes the same action being executed by others. Although it is well established that emotion modulates the motor system, the effect of observing other individuals acting in an emotional context is particularly elusive. The main aim of this study was to investigate the effect induced by the observation of grasping directed to emotion-laden objects upon corticospinal excitability (CSE). Participants classified video-clips depicting the right-hand of an actor grasping emotion-laden objects. Twenty video-clips differing in terms of valence but balanced in arousal level were selected. Motor evoked potentials (MEPs) were then recorded from the first dorsal interosseous using transcranial magnetic stimulation (TMS) while the participants observed the selected emotional video-clips. During the video-clip presentation, TMS pulses were randomly applied at one of two different time points of grasping: (1) maximum grip aperture, and (2) object contact time. CSE was higher during the observation of grasping directed to unpleasant objects compared to pleasant ones. These results indicate that when someone observes an action of grasping directed to emotion-laden objects, the effect of the object valence promotes a specific modulation over the motor system. PMID:27625602

  16. Observing Grasping Actions Directed to Emotion-Laden Objects: Effects upon Corticospinal Excitability.

    PubMed

    Nogueira-Campos, Anaelli A; Saunier, Ghislain; Della-Maggiore, Valeria; De Oliveira, Laura A S; Rodrigues, Erika C; Vargas, Claudia D

    2016-01-01

    The motor system is recruited whenever one executes an action as well as when one observes the same action being executed by others. Although it is well established that emotion modulates the motor system, the effect of observing other individuals acting in an emotional context is particularly elusive. The main aim of this study was to investigate the effect induced by the observation of grasping directed to emotion-laden objects upon corticospinal excitability (CSE). Participants classified video-clips depicting the right-hand of an actor grasping emotion-laden objects. Twenty video-clips differing in terms of valence but balanced in arousal level were selected. Motor evoked potentials (MEPs) were then recorded from the first dorsal interosseous using transcranial magnetic stimulation (TMS) while the participants observed the selected emotional video-clips. During the video-clip presentation, TMS pulses were randomly applied at one of two different time points of grasping: (1) maximum grip aperture, and (2) object contact time. CSE was higher during the observation of grasping directed to unpleasant objects compared to pleasant ones. These results indicate that when someone observes an action of grasping directed to emotion-laden objects, the effect of the object valence promotes a specific modulation over the motor system. PMID:27625602

  17. Observations of the directional distribution of the wind energy input function over swell waves

    NASA Astrophysics Data System (ADS)

    Shabani, Behnam; Babanin, Alex V.; Baldock, Tom E.

    2016-02-01

    Field measurements of wind stress over shallow water swell traveling in different directions relative to the wind are presented. The directional distribution of the measured stresses is used to confirm the previously proposed but unverified directional distribution of the wind energy input function. The observed wind energy input function is found to follow a much narrower distribution (β∝cos⁡3.6θ) than the Plant (1982) cosine distribution. The observation of negative stress angles at large wind-wave angles, however, indicates that the onset of negative wind shearing occurs at about θ≈ 50°, and supports the use of the Snyder et al. (1981) directional distribution. Taking into account the reverse momentum transfer from swell to the wind, Snyder's proposed parameterization is found to perform exceptionally well in explaining the observed narrow directional distribution of the wind energy input function, and predicting the wind drag coefficients. The empirical coefficient (ɛ) in Snyder's parameterization is hypothesised to be a function of the wave shape parameter, with ɛ value increasing as the wave shape changes between sinusoidal, sawtooth, and sharp-crested shoaling waves.

  18. Ethical aspects of directly observed treatment for tuberculosis: a cross-cultural comparison

    PubMed Central

    2013-01-01

    Background Tuberculosis is a major global public health challenge, and a majority of countries have adopted a version of the global strategy to fight Tuberculosis, Directly Observed Treatment, Short Course (DOTS). Drawing on results from research in Ethiopia and Norway, the aim of this paper is to highlight and discuss ethical aspects of the practice of Directly Observed Treatment (DOT) in a cross-cultural perspective. Discussion Research from Ethiopia and Norway demonstrates that the rigid enforcement of directly observed treatment conflicts with patient autonomy, dignity and integrity. The treatment practices, especially when imposed in its strictest forms, expose those who have Tuberculosis to extra burdens and costs. Socially disadvantaged groups, such as the homeless, those employed as day labourers and those lacking rights as employees, face the highest burdens. Summary From an ethical standpoint, we argue that a rigid practice of directly observed treatment is difficult to justify, and that responsiveness to social determinants of Tuberculosis should become an integral part of the management of Tuberculosis. PMID:23819555

  19. Standardizing the Pre-Licensure Supervision Process: A Commentary on Advocating for Direct Observation of Skills

    ERIC Educational Resources Information Center

    Gray, Neal D.; Erickson, Paul

    2013-01-01

    The present paper advocates for standardized regulations and laws for supervision of pre-licensed counselors in the United States, particularly for direct observation of clinical skills. A review of regulations by the American Counseling Association (ACA) Office of Professional Affairs (2012) reveals that only two states (Arizona and North…

  20. Three-Item Direct Observation Screen (TIDOS) for Autism Spectrum Disorder

    ERIC Educational Resources Information Center

    Oner, Pinar; Oner, Ozgur; Munir, Kerim

    2014-01-01

    We compared ratings on the Three-Item Direct Observation Screen test for autism spectrum disorders completed by pediatric residents with the Social Communication Questionnaire parent reports as an augmentative tool for improving autism spectrum disorder screening performance. We examined three groups of children (18-60 months) comparable in age…

  1. Observational Learning of Academic and Social Behaviors during Small-Group Direct Instruction

    ERIC Educational Resources Information Center

    Ledford, Jennifer R.; Wolery, Mark

    2015-01-01

    Many studies have shown that small-group direct instruction is effective and efficient for teaching students with and without disabilities, although relatively few studies have been conducted with heterogeneous groups of preschool participants. In addition, previous studies have primarily assessed whether observational learning occurred for…

  2. Considering Systematic Direct Observation after a Century of Research--Commentary on the Special Issue

    ERIC Educational Resources Information Center

    Stichter, Janine P.; Riley-Tillman, T. Chris

    2014-01-01

    Systematic Direct Observation (SDO) has played a pivotal role in the field of Emotional and/or Behavioral Disorders (EBD) since its inception as a key part of understanding more about the behaviors, contexts that impact them, and the effective supports necessary for this population. This methodology is an ongoing charge for everyone. The authors…

  3. The Impact of Observation Duration on the Accuracy of Data Obtained from Direct Behavior Rating (DBR)

    ERIC Educational Resources Information Center

    Riley-Tillman, T. Chris; Christ, Theodore J.; Chafouleas, Sandra M.; Boice-Mallach, Christina H.; Briesch, Amy

    2011-01-01

    In this study, evaluation of direct behavior rating (DBR) occurred with regard to two primary areas: (a) accuracy of ratings with varied instrumentation (anchoring: proportional or absolute) and procedures (observation length: 5 min, 10 min, or 20 min) and (b) one-week test-retest reliability. Participants viewed video clips of a typical third…

  4. Direct Binding to Replication Protein A (RPA)-coated Single-stranded DNA Allows Recruitment of the ATR Activator TopBP1 to Sites of DNA Damage.

    PubMed

    Acevedo, Julyana; Yan, Shan; Michael, W Matthew

    2016-06-17

    A critical event for the ability of cells to tolerate DNA damage and replication stress is activation of the ATR kinase. ATR activation is dependent on the BRCT (BRCA1 C terminus) repeat-containing protein TopBP1. Previous work has shown that recruitment of TopBP1 to sites of DNA damage and stalled replication forks is necessary for downstream events in ATR activation; however, the mechanism for this recruitment was not known. Here, we use protein binding assays and functional studies in Xenopus egg extracts to show that TopBP1 makes a direct interaction, via its BRCT2 domain, with RPA-coated single-stranded DNA. We identify a point mutant that abrogates this interaction and show that this mutant fails to accumulate at sites of DNA damage and that the mutant cannot activate ATR. These data thus supply a mechanism for how the critical ATR activator, TopBP1, senses DNA damage and stalled replication forks to initiate assembly of checkpoint signaling complexes. PMID:27129245

  5. Metabolic profiling of plant extracts using direct-injection electrospray ionization mass spectrometry allows for high-throughput phenotypic characterization according to genetic and environmental effects.

    PubMed

    García-Flores, Martín; Juárez-Colunga, Sheila; García-Casarrubias, Adrián; Trachsel, Samuel; Winkler, Robert; Tiessen, Axel

    2015-01-28

    In comparison to the exponential increase of genotyping methods, phenotyping strategies are lagging behind in agricultural sciences. Genetic improvement depends upon the abundance of quantitative phenotypic data and the statistical partitioning of variance into environmental, genetic, and random effects. A metabolic phenotyping strategy was adapted to increase sample throughput while saving reagents, reducing cost, and simplifying data analysis. The chemical profiles of stem extracts from maize plants grown under low nitrogen (LN) or control trial (CT) were analyzed using optimized protocols for direct-injection electrospray ionization mass spectrometry (DIESI-MS). Specific ions significantly decreased or increased because of environmental (LN versus CT) or genotypic effects. Biochemical profiling with DIESI-MS had a superior cost-benefit compared to other standard analytical technologies (e.g., ultraviolet, near-infrared reflectance spectroscopy, high-performance liquid chromatography, and gas chromatography with flame ionization detection) routinely used for plant breeding. The method can be successfully applied in maize, strawberry, coffee, and other crop species. PMID:25588121

  6. Expression of fluorescent proteins within the repeat long region of the Marek's disease virus genome allows direct identification of infected cells while retaining full pathogenicity.

    PubMed

    Jarosinski, Keith W; Donovan, Kathleen M; Du, Guixin

    2015-04-01

    Marek's disease virus (MDV) is a lymphotropic alphaherpesvirus and causes Marek's disease (MD) in chickens. RLORF4 is an MDV-specific gene located in the repeat long (RL) regions of the genome and is directly involved in attenuation. In this report, we generated recombinant (r)MDVs in which eGFP or mRFP was inserted in-frame of the 3' end of the RLORF4 gene. In vitro growth was unaffected and infected cells could be identified by using fluorescent microscopy. Interestingly, though inserted in-frame with RLORF4, eGFP and mRFP were expressed alone, confirming mRNA expression and splicing within the RL of MDV is complex. In vivo, rMDVs expressing mRFP or eGFP caused tumors similar to wild-type MDV. Fluorescent protein expression could be seen in spleen, tumor, and feather follicle epithelial cells. These results show that expression of fluorescent proteins within the RL region results in fluorescent rMDVs that still maintains full pathogenicity in the chicken. PMID:25725150

  7. A Novel 7-Single Nucleotide Polymorphism-Based Clonotyping Test Allows Rapid Prediction of Antimicrobial Susceptibility of Extraintestinal Escherichia coli Directly From Urine Specimens

    PubMed Central

    Tchesnokova, Veronika; Avagyan, Hovhannes; Billig, Mariya; Chattopadhyay, Sujay; Aprikian, Pavel; Chan, Diana; Pseunova, Julietta; Rechkina, Elena; Riddell, Kim; Scholes, Delia; Fang, Ferric C.; Johnson, James R.; Sokurenko, Evgeni V.

    2016-01-01

    Background. Escherichia coli is a highly clonal pathogen. Extraintestinal isolates belong to a limited number of genetically related groups, which often exhibit characteristic antimicrobial resistance profiles. Methods. We developed a rapid clonotyping method for extraintestinal E coli based on detection of the presence or absence of 7 single nucleotide polymorphisms (SNPs) within 2 genes (fumC and fimH). A reference set of 2559 E coli isolates, primarily of urinary origin, was used to predict the resolving power of the 7-SNP-based typing method, and 582 representative strains from this set were used to evaluate test robustness. Results. Fifty-four unique SNP combinations (“septatypes”) were identified in the reference strains. These septatypes yielded a clonal group resolution power on par with that of traditional multilocus sequence typing. In 72% of isolates, septatype identity predicted sequence type identity with at least 90% (mean, 97%) accuracy. Most septatypes exhibited highly distinctive antimicrobial susceptibility profiles. The 7-SNP-based test could be performed with high specificity and sensitivity using single or multiplex conventional polymerase chain reaction (PCR) and quantitative PCR. In the latter format, E coli presence and septatype identity were determined directly in urine specimens within 45 minutes with bacterial loads as low as 102 colony-forming units/mL and, at clinically significant bacterial loads, with 100% sensitivity and specificity. Conclusions. 7-SNP-based typing of E coli can be used for both epidemiological studies and clinical diagnostics, which could greatly improve the empirical selection of antimicrobial therapy. PMID:26925427

  8. A direct observation the asteroid's structure from deep interior to regolith: why and how do it?

    NASA Astrophysics Data System (ADS)

    Herique, A.; Kofman, W. W.

    2013-12-01

    The internal structure of asteroids is still poorly known and has never been measured directly. Our knowledge is relying entirely on inferences from remote sensing observations of the surface, and theoretical modeling. Is the body a monolithic piece of rock or a rubble-pile, an aggregate of boulders held together by gravity and how much porosity it contains, both in the form of micro-scale or macro-scale porosity? What is the typical size of the constituent blocs? Are these blocs homogeneous or heterogeneous? Is the body a defunct or dormant comet and such MBC can become active? The body is covered by a regolith from whose properties remains largely unknown in term of depth, size distribution and spatial variation. Is resulting from fine particles re-accretion or from thermal fracturing? What are its coherent forces? How to model is thermal conductivity while this parameter is so important to estimate Yarkowsky and Yorp effects? Knowing asteroid deep interior and regolith structure is a key point for a better understanding of the asteroid accretion and dynamical evolution. There is no way to determine this from ground-based observation. Radar operating from a spacecraft is the only technique capable of achieving this science objective of characterizing the internal structure and heterogeneity from submetric to global scale for the science benefit as well as for the planetary defence and human exploration. The deep interior structure tomography requires low-frequency radar to penetrate throughout the complete body. The radar wave propagation delay and the received power are related to the complex dielectric permittivity (i.e to the composition and microporosity) and the small scale heterogeneities (scattering losses) while the spatial variation of the signal and the multiple paths provide information on the presence of heterogeneities (variations in composition or porosity), layers, ice lens. A partial coverage will provide "cuts" of the body when a dense coverage

  9. Direct observation of size scaling and elastic interaction between nano-scale defects in collision cascades

    NASA Astrophysics Data System (ADS)

    Yi, X.; Sand, A. E.; Mason, D. R.; Kirk, M. A.; Roberts, S. G.; Nordlund, K.; Dudarev, S. L.

    2015-05-01

    Using in situ transmission electron microscopy, we have directly observed nano-scale defects formed in ultra-high-purity tungsten by low-dose high-energy self-ion irradiation at 30 K. At cryogenic temperature lattice defects have reduced mobility, so these microscope observations offer a window on the initial, primary damage caused by individual collision cascade events. Electron microscope images provide direct evidence for a power-law size distribution of nano-scale defects formed in high-energy cascades, with an upper size limit independent of the incident ion energy, as predicted by Sand et al. (EPL, 103 (2013) 46003). Furthermore, the analysis of pair distribution functions of defects observed in the micrographs shows significant intra-cascade spatial correlations consistent with strong elastic interaction between the defects.

  10. A Review of Direct Observation Research within the Past Decade in the Field of Emotional and Behavioral Disorders

    ERIC Educational Resources Information Center

    Adamson, Reesha M.; Wachsmuth, Sean T.

    2014-01-01

    This study reviewed prominent journals within the field of emotional and behavioral disorders to identify direct observation approaches, reported reliability statistics, and key features of direct observation. Selected journals were systematically reviewed for the past 10 years identifying and quantifying specific direct observation systems and…

  11. Direct Observation of Localized Radial Oxygen Migration in Functioning Tantalum Oxide Memristors.

    PubMed

    Kumar, Suhas; Graves, Catherine E; Strachan, John Paul; Grafals, Emmanuelle Merced; Kilcoyne, Arthur L David; Tyliszczak, Tolek; Weker, Johanna Nelson; Nishi, Yoshio; Williams, R Stanley

    2016-04-13

    Oxygen migration in tantalum oxide, a promising next-generation storage material, is studied using in operando X-ray absorption spectromicroscopy. This approach allows a physical description of the evolution of conduction channel and eventual device failure. The observed ring-like patterns of oxygen concentration are modeled using thermophoretic forces and Fick diffusion, establishing the critical role of temperature-driven oxygen migration. PMID:26833926

  12. THE STRUCTURE OF A SELF-GRAVITATING PROTOPLANETARY DISK AND ITS IMPLICATIONS FOR DIRECT IMAGING OBSERVATIONS

    SciTech Connect

    Muto, Takayuki

    2011-09-20

    We consider the effects of self-gravity on the hydrostatic balance in the vertical direction of a gaseous disk and discuss the possible signature of the self-gravity that may be captured by direct imaging observations of protoplanetary disks in the future. In this paper, we consider a vertically isothermal disk in order to isolate the effects of self-gravity. The specific disk model we consider in this paper is the one with a radial surface density gap, at which the Toomre's Q-parameter of the disk varies rapidly in the radial direction. We calculate the vertical structure of the disk including the effects of self-gravity. We then calculate the scattered light and the dust thermal emission. We find that if the disk is massive enough and the effects of self-gravity come into play, a weak bump-like structure at the gap edge appears in the near-infrared (NIR) scattered light, while no such bump-like structure is seen in the submillimeter (sub-mm) dust continuum image. The appearance of the bump is caused by the variation of the height of the surface in the NIR wavelength. If such a bump-like feature is detected in future direct imaging observations, combined with sub-mm observations, it will give us useful information about the physical states of the disk.

  13. Signatures of semi-direct radiative forcing by absorbing aerosols in satellite observations and models

    NASA Astrophysics Data System (ADS)

    Wilcox, E. M.; Hosseinpour, F.; Colarco, P. R.

    2014-12-01

    Semi-direct radiative forcing of climate occurs when interactions between aerosols and radiative fluxes in the atmosphere yield a dynamical response in clouds. Semi-direct forcing is typically thought to be a positive radiative forcing whereby soot and biomass burning aerosols absorb sunlight and burn-off clouds. However, a negative semi-direct forcing is suspected in at least two regimes, the summertime Southeast Atlantic Ocean and the wintertime North Indian Ocean, where the heating profile by aerosol absorption by solar radiation is elevated above the elevation of the low clouds. Here we use a combination of satellite data and a model simulation to further characterize the signature of semi-direct radiative forcing in these two locations and elsewhere on the globe. We apply CERES albedos, Calipso profiles of aerosol extinction and cloud-top altitude, and a simulation with the Goddard Earth Observing System Model version 5 (GEOS-5) Earth system model with meteorology constrained by MERRA and an assimilation of MODIS AOT (MERRAero). to quantify the vertical heating profile by aerosols under clear and cloudy skies. We seek to determine: (1) where aerosol heating by soot and biomass burning aerosol is occurring; (2) where vertically in the column the heating is occurring relative to the observed level of low cloud development; and (3) whether the variations of albedo with aerosol forcing suggest a positive, negative, or inconclusive semi-direct radiative forcing.

  14. Unimolecular Thermal Decomposition of Phenol and d5-Phenol: Direct Observation of Cyclopentadiene Formation via Cyclohexadienone

    SciTech Connect

    Scheer, A. M.; Mukarakate, C.; Robichaud, D. J.; Nimlos, M. R.; Carstensen, H. H.; Barney, E. G.

    2012-01-28

    The pyrolyses of phenol and d{sub 5}-phenol (C{sub 6}H{sub 5}OH and C{sub 6}D{sub 5}OH) have been studied using a high temperature, microtubular ({mu}tubular) SiC reactor. Product detection is via both photon ionization (10.487 eV) time-of-flight mass spectrometry and matrix isolation infrared spectroscopy. Gas exiting the heated reactor (375 K-1575 K) is subject to a free expansion after a residence time in the {mu}tubular reactor of approximately 50-100 {micro}s. The expansion from the reactor into vacuum rapidly cools the gas mixture and allows the detection of radicals and other highly reactive intermediates. We find that the initial decomposition steps at the onset of phenol pyrolysis are enol/keto tautomerization to form cyclohexadienone followed by decarbonylation to produce cyclopentadiene; C{sub 6}H{sub 5}OH {yields} c-C{sub 6}H{sub 6} = O {yields} c-C{sub 5}H{sub 6} + CO. The cyclopentadiene loses a H atom to generate the cyclopentadienyl radical which further decomposes to acetylene and propargyl radical; c-C{sub 5}H{sub 6} {yields} c-C{sub 5}H{sub 5} + H {yields} HC {triple_bond} CH + HCCCH{sub 2}. At higher temperatures, hydrogen loss from the PhO-H group to form phenoxy radical followed by CO ejection to generate the cyclopentadienyl radical likely contributes to the product distribution; C{sub 6}H{sub 5}O-H {yields} C{sub 6}H{sub 5}O + H {yields} c-C{sub 5}H{sub 5} + CO. The direct decarbonylation reaction remains an important channel in the thermal decomposition mechanisms of the dihydroxybenzenes. Both catechol (o-HO-C{sub 6}H{sub 4}-OH) and hydroquinone (p-HO-C{sub 6}H{sub 4}-OH) are shown to undergo decarbonylation at the onset of pyrolysis to form hydroxycyclopentadiene. In the case of catechol, we observe that water loss is also an important decomposition channel at the onset of pyrolysis.

  15. Mid-Cretaceous charred fossil flowers reveal direct observation of arthropod feeding strategies.

    PubMed

    Hartkopf-Fröder, Christoph; Rust, Jes; Wappler, Torsten; Friis, Else Marie; Viehofen, Agnes

    2012-04-23

    Although plant-arthropod relationships underpin the dramatic rise in diversity and ecological dominance of flowering plants and their associated arthropods, direct observations of such interactions in the fossil record are rare, as these ephemeral moments are difficult to preserve. Three-dimensionally preserved charred remains of Chloranthistemon flowers from the Late Albian to Early Cenomanian of Germany preserve scales of mosquitoes and an oribatid mite with mouthparts inserted into the pollen sac. Mosquitoes, which today are frequent nectar feeders, and the mite were feeding on pollen at the time wildfire consumed the flowers. These findings document directly arthropod feeding strategies and their role in decomposition. PMID:21900310

  16. Mid-Cretaceous charred fossil flowers reveal direct observation of arthropod feeding strategies

    PubMed Central

    Hartkopf-Fröder, Christoph; Rust, Jes; Wappler, Torsten; Friis, Else Marie; Viehofen, Agnes

    2012-01-01

    Although plant–arthropod relationships underpin the dramatic rise in diversity and ecological dominance of flowering plants and their associated arthropods, direct observations of such interactions in the fossil record are rare, as these ephemeral moments are difficult to preserve. Three-dimensionally preserved charred remains of Chloranthistemon flowers from the Late Albian to Early Cenomanian of Germany preserve scales of mosquitoes and an oribatid mite with mouthparts inserted into the pollen sac. Mosquitoes, which today are frequent nectar feeders, and the mite were feeding on pollen at the time wildfire consumed the flowers. These findings document directly arthropod feeding strategies and their role in decomposition. PMID:21900310

  17. Quasar Redshifts from S-CAM Observations: Direct Colour Determination of ~12 Gyr-old Photons

    NASA Astrophysics Data System (ADS)

    de Bruijne, J. H. J.; Reynolds, A. P.; Perryman, M. A. C.; Peacock, A.; Favata, F.; Rando, N.; Martin, D.; Verhoeve, P.; Christlieb, N.

    2002-10-01

    CCDs have revolutionised astronomy in the last quarter of the 20th century, yet measuring energy distributions of celestial objects still requires the indirect methods of filter photometry or dispersive spectroscopy. The development of superconducting tunnel junction (STJ) detectors has opened up the possibility of measuring individual optical photon energies directly. The first time-and spectrally-resolved observations of cataclysmic variables and pulsars using these techniques have been reported, and the first direct measurements of the redshifts of quasars using an imaging detector with intrinsic energy resolution were published early this year.

  18. Diffusion of a Highly-Charged Supramolecular Assembly: Direct Observation of Ion-Association in Water

    SciTech Connect

    University of California, Berkeley; Lawrence Berkeley National Laboratory; Raymond, Kenneth; Pluth, Michael D.; Tiedemann, Bryan E.F.; van Halbeek, Herman; Nunlist, Rudi; Raymond, Kenneth N.

    2007-10-22

    Understanding the solution behavior of supramolecular assemblies is essential for a full understanding of the formation and chemistry of synthetic host-guest systems. While the interaction between host and guest molecules is generally the focus of mechanistic studies of host-guest complexes, the interaction of the host-guest complex with other species in solution remains largely unknown, although in principle accessible by diffusion studies. Several NMR techniques are available to monitor diffusion and have recently been reviewed. Pulsed gradient spin-echo (PGSE) NMR methods have attracted increasing interest, since they allow diffusion coefficients to be measured with high accuracy; they have been successfully used with observation of {sup 7}Li and {sup 31}P nuclei as well as with {sup 1}H NMR. We report here the direct measurement of diffusion coefficients to observe ion-association interactions by counter cations with a highly-charged supramolecular assembly. Raymond and coworkers have described the design and chemistry of a class of metal-ligand supramolecular assemblies over the past decade. The [Ga{sub 4}L{sub 6}]{sup 12-} (L = 1,5-bis(2,3-dihydroxybenzamido)naphthalene) (1) (Figure 1) assembly has garnered the most attention, with the exploration of the dynamics and mechanism of guest exchange as well as the ability of 1 to achieve either stoichiometric or catalytic reactions inside its interior cavity. Recent studies have revealed the importance of counter cations in solution on the chemistry of 1. During the mechanistic study of the C-H bond activation of aldehydes by [Cp*Ir(PMe{sub 3})(olefin){sup +} {contained_in} 1]{sup 11-} a stepwise guest dissociation mechanism with an ion-paired intermediate was proposed. Similarly, in the mechanism for the hydrolysis of iminium cations generated from the 3-aza Cope rearrangement of enammonium cations in 1, the presence of an exterior ion association was part of the kinetic model. To further substantiate the

  19. Direct Observation of Field and Temperature Induced Domain Replication in Dipolar Coupled Perpendicular Anisotropy Films

    SciTech Connect

    Hauet, T.; Gunther, C.M.; Pfau, B.; Eisebitt, S.; Fischer, P.; Rick, R. L.; Thiele, J.-U.; Hellwig, O.; Schabes, M.E.

    2007-07-01

    Dipolar interactions in a soft/Pd/hard [CoNi/Pd]{sub 30}/Pd/[Co/Pd]{sub 20} multilayer system, where a thick Pd layer between two ferromagnetic units prevents direct exchange coupling, are directly revealed by combining magnetometry and state-of-the-art layer resolving soft x-ray imaging techniques with sub-100-nm spatial resolution. The domains forming in the soft layer during external magnetic field reversal are found to match the domains previously trapped in the hard layer. The low Curie temperature of the soft layer allows varying its intrinsic parameters via temperature and thus studying the competition with dipolar fields due to the domains in the hard layer. Micromagnetic simulations elucidate the role of [CoNi/Pd] magnetization, exchange, and anisotropy in the duplication process. Finally, thermally driven domain replication in remanence during temperature cycling is demonstrated.

  20. Protein structure. Direct observation of structure-function relationship in a nucleic acid-processing enzyme.

    PubMed

    Comstock, Matthew J; Whitley, Kevin D; Jia, Haifeng; Sokoloski, Joshua; Lohman, Timothy M; Ha, Taekjip; Chemla, Yann R

    2015-04-17

    The relationship between protein three-dimensional structure and function is essential for mechanism determination. Unfortunately, most techniques do not provide a direct measurement of this relationship. Structural data are typically limited to static pictures, and function must be inferred. Conversely, functional assays usually provide little information on structural conformation. We developed a single-molecule technique combining optical tweezers and fluorescence microscopy that allows for both measurements simultaneously. Here we present measurements of UvrD, a DNA repair helicase, that directly and unambiguously reveal the connection between its structure and function. Our data reveal that UvrD exhibits two distinct types of unwinding activity regulated by its stoichiometry. Furthermore, two UvrD conformational states, termed "closed" and "open," correlate with movement toward or away from the DNA fork. PMID:25883359

  1. Gravity Waves Generated by Convection: A New Idealized Model Tool and Direct Validation with Satellite Observations

    NASA Astrophysics Data System (ADS)

    Alexander, M. Joan; Stephan, Claudia

    2015-04-01

    In climate models, gravity waves remain too poorly resolved to be directly modelled. Instead, simplified parameterizations are used to include gravity wave effects on model winds. A few climate models link some of the parameterized waves to convective sources, providing a mechanism for feedback between changes in convection and gravity wave-driven changes in circulation in the tropics and above high-latitude storms. These convective wave parameterizations are based on limited case studies with cloud-resolving models, but they are poorly constrained by observational validation, and tuning parameters have large uncertainties. Our new work distills results from complex, full-physics cloud-resolving model studies to essential variables for gravity wave generation. We use the Weather Research Forecast (WRF) model to study relationships between precipitation, latent heating/cooling and other cloud properties to the spectrum of gravity wave momentum flux above midlatitude storm systems. Results show the gravity wave spectrum is surprisingly insensitive to the representation of microphysics in WRF. This is good news for use of these models for gravity wave parameterization development since microphysical properties are a key uncertainty. We further use the full-physics cloud-resolving model as a tool to directly link observed precipitation variability to gravity wave generation. We show that waves in an idealized model forced with radar-observed precipitation can quantitatively reproduce instantaneous satellite-observed features of the gravity wave field above storms, which is a powerful validation of our understanding of waves generated by convection. The idealized model directly links observations of surface precipitation to observed waves in the stratosphere, and the simplicity of the model permits deep/large-area domains for studies of wave-mean flow interactions. This unique validated model tool permits quantitative studies of gravity wave driving of regional

  2. Validation of simulated flow direction and hydraulic gradients with hydraulic head observations using open source GIS

    NASA Astrophysics Data System (ADS)

    Vandersteen, Katrijn; Rogiers, Bart; Gedeon, Matej

    2015-04-01

    It is recommended to check hydraulic gradients and flow directions predicted by a groundwater flow model that is calibrated solely with hydraulic head observations. It has been demonstrated in literature that substantial errors can be made when the model is not calibrated on these state variables. Therefore, in this work, we perform a validation of a steady-state groundwater flow model, representing part of the Neogene aquifer (60 km2) in Belgium. This model was developed and calibrated solely on groundwater head measurements, in the framework of the environmental impact assessment of the near surface repository for low- and intermediate-level short-lived waste, realized by ONDRAF/NIRAS at Dessel, Belgium. Horizontal flow directions, horizontal and vertical gradients for the entire area of the groundwater model were estimated from measurements at shallow monitoring wells within the groundwater flow model domain, and compared to the flow directions and vertical gradients predicted by the model. For obtaining horizontal flow directions and gradients, triangulation of groundwater levels was performed for combinations of three neighboring hydraulic head observations in the same hydrogeological layer within the model. The simulated equivalents at the same monitoring wells were used to repeat the same methodology, and calculate flow direction components. This analysis was performed in SAGA GIS and was visualized through QGIS. Comparison of the flow directions and flow gradients obtained from measurements and simulations gives an indication on the model performance. The calculations were performed for three sandy hydrogeological units used in the model. A similar procedure was performed for the vertical hydraulic head gradients, where any combination of two hydraulic head observations at the same location but at different levels within the aquifer were used to validate the vertical gradients predicted by the model. Besides model validation on average hydraulic heads, the

  3. Using Surface Observations to Constrain the Direction and Magnitude of Mantle Flow Beneath Western North America

    NASA Astrophysics Data System (ADS)

    Holt, W. E.; Silver, P. G.

    2001-12-01

    While the motions of the surface tectonic plates are well determined, the accompanying horizontal mantle flow is not. Observations of surface deformation (GPS velocities and Quaternary fault slip rates) and upper mantle seismic anisotropy are combined for the first time, to provide a direct estimate of this flow field. We apply our investigation to western North America where seismic tomography shows a relatively thin lithosphere. Here the likely source of shear wave anisotropy results from a deformation fabric associated with the differential horizontal motion between the base of the lithosphere and the underlying mantle. For a vertically propagating shear wave recorded at a single station, and for mantle strains of order unity, the fast polarization direction, φ , of a split shear wave will be parallel to the direction of progressive simple shear, defined by this differential motion between lithosphere and underlying mantle. If the motion of the overlying lithospehre is known both within and across a plate boundary zone, such as western North America, then the direction and magnitude of mantle flow beneath the plate boundary zone can be uniquely determined with three or more observations of fast polarization directions. Within the Pacific-North American Plate boundary zone in western North America we find that the mantle velocity is 5.0+/-1.5 cm/yr and directed E-NE in a hotspot frame, nearly opposite to the direction of North American plate motion (WSW). The flow is only weakly coupled to the motion of the surface plates, producing a weak drag force. This flow field is most likely due to mantle density heterogeneity associated with the sinking of the old Farallon slab beneath North America. The last few decades have seen the development of two basically incompatible views of the plate-mantle system. The tectonophysical view assumes effective decoupling between the plate and a stationary mantle by a well developed asthenosphere. The plates are essentially 'self

  4. Direct observation of electric field induced pattern formation and particle aggregation in ferrofluids

    NASA Astrophysics Data System (ADS)

    Rajnak, Michal; Petrenko, Viktor I.; Avdeev, Mikhail V.; Ivankov, Olexandr I.; Feoktystov, Artem; Dolnik, Bystrik; Kurimsky, Juraj; Kopcansky, Peter; Timko, Milan

    2015-08-01

    Ferrofluids typically respond to magnetic fields and can be manipulated by external magnetic fields. Here, we report on formation of visually observable patterns in a diluted low-polarity ferrofluid exposed to external electric fields. This presents a specific type of ferrofluid structure driven by a combined effect of electrohydrodynamics and electrical body forces. The free charge and permittivity variation are considered to play a key role in the observed phenomenon. The corresponding changes in the ferrofluid structure have been found at nanoscale as well. By small-angle neutron scattering (SANS), we show that the magnetic nanoparticles aggregate in direct current (dc) electric field with a strong dependence on the field intensity. The anisotropic aggregates preferably orient in the direction of the applied electric field. Conducting SANS experiments with alternating current (ac) electric fields of various frequencies, we found a critical frequency triggering the aggregation process. Our experimental study could open future applications of ferrofluids based on insulating liquids.

  5. Direct observation of electric field induced pattern formation and particle aggregation in ferrofluids

    SciTech Connect

    Rajnak, Michal; Kopcansky, Peter; Timko, Milan; Petrenko, Viktor I.; Avdeev, Mikhail V.; Ivankov, Olexandr I.; Feoktystov, Artem; Dolnik, Bystrik; Kurimsky, Juraj

    2015-08-17

    Ferrofluids typically respond to magnetic fields and can be manipulated by external magnetic fields. Here, we report on formation of visually observable patterns in a diluted low-polarity ferrofluid exposed to external electric fields. This presents a specific type of ferrofluid structure driven by a combined effect of electrohydrodynamics and electrical body forces. The free charge and permittivity variation are considered to play a key role in the observed phenomenon. The corresponding changes in the ferrofluid structure have been found at nanoscale as well. By small-angle neutron scattering (SANS), we show that the magnetic nanoparticles aggregate in direct current (dc) electric field with a strong dependence on the field intensity. The anisotropic aggregates preferably orient in the direction of the applied electric field. Conducting SANS experiments with alternating current (ac) electric fields of various frequencies, we found a critical frequency triggering the aggregation process. Our experimental study could open future applications of ferrofluids based on insulating liquids.

  6. Direct observation of dark excitons in individual carbon nanotubes: inhomogeneity in the exchange splitting.

    PubMed

    Srivastava, Ajit; Htoon, Han; Klimov, Victor I; Kono, Junichiro

    2008-08-22

    We report the direct observation of spin-singlet dark excitons in individual single-walled carbon nanotubes through low-temperature micro-magneto-photoluminescence spectroscopy. A magnetic field (B) applied along the tube axis brightened the dark state, leading to the emergence of a new emission peak. The peak rapidly grew in intensity with increasing B at the expense of the originally dominated bright exciton peak and became dominant at B>3 T. This behavior, universally observed for more than 50 tubes of different chiralities, can be quantitatively modeled by incorporating the Aharonov-Bohm effect and intervalley Coulomb mixing. The directly measured dark-bright splitting values were 1-4 meV for tube diameters 1.0-1.3 nm. Scatter in the splitting value emphasizes the role of the local environment surrounding a nanotube in determining its excitonic fine structure. PMID:18764659

  7. Direct Spectroscopic Observation of a Shallow Hydrogenlike Donor State in Insulating SrTiO3

    NASA Astrophysics Data System (ADS)

    Salman, Z.; Prokscha, T.; Amato, A.; Morenzoni, E.; Scheuermann, R.; Sedlak, K.; Suter, A.

    2014-10-01

    We present a direct spectroscopic observation of a shallow hydrogenlike muonium state in SrTiO3 which confirms the theoretical prediction that interstitial hydrogen may act as a shallow donor in this material. The formation of this muonium state is temperature dependent and appears below ˜70 K. From the temperature dependence we estimate an activation energy of ˜50 meV in the bulk and ˜23 meV near the free surface. The field and directional dependence of the muonium precession frequencies further supports the shallow impurity state with a rare example of a fully anisotropic hyperfine tensor. From these measurements we determine the strength of the hyperfine interaction and propose that the muon occupies an interstitial site near the face of the oxygen octahedron in SrTiO3. The observed shallow donor state provides new insight for tailoring the electronic and optical properties of SrTiO3-based oxide interface systems.

  8. Microbunching instability in relativistic electron bunches: direct observations of the microstructures using ultrafast YBCO detectors.

    PubMed

    Roussel, E; Evain, C; Szwaj, C; Bielawski, S; Raasch, J; Thoma, P; Scheuring, A; Hofherr, M; Ilin, K; Wünsch, S; Siegel, M; Hosaka, M; Yamamoto, N; Takashima, Y; Zen, H; Konomi, T; Adachi, M; Kimura, S; Katoh, M

    2014-08-29

    Relativistic electron bunches circulating in accelerators are subjected to a dynamical instability leading to microstructures at millimeter to centimeter scale. Although this is a well-known fact, direct experimental observations of the structures, or the field that they emit, remained up to now an open problem. Here, we report the direct, shot-by-shot, time-resolved recording of the shapes (including envelope and carrier) of the pulses of coherent synchrotron radiation that are emitted, and that are a "signature" of the electron bunch microstructure. The experiments are performed on the UVSOR-III storage ring, using electrical field sensitive YBa2Cu3O(7-x) thin-film ultrafast detectors. The observed patterns are subjected to permanent drifts, that can be explained from a reasoning in phase space, using macroparticle simulations. PMID:25215987

  9. Direct observation of surface plasmons in YBCO by attenuated total reflection of light in the infrared

    NASA Astrophysics Data System (ADS)

    Walmsley, D. G.; Smyth, C. C.; Sellai, A.; McCafferty, P. G.; Dawson, P.; Morrow, T.; Graham, W. G.

    1994-02-01

    Surface plasmons have been observed directly in YBCO films in an Otto-geometry attenuated total reflection measurement at a wavelength of 3.392 μm. The laser deposited films are c-axis oriented on an MgO substrate. This observation confirms theoretical deductions from complex dielectric function data. Measured data have been fitted to a theoretical model and are compared with the optical constants determined by Bozovic [1]. The investigations have been extended to films with other orientations to investigate whether material anisotropy is reflected in the results and non-metallic behaviour is found.

  10. Direct Observation of Gigahertz Coherent Guided Acoustic Phonons in Free-Standing Single Copper Nanowires.

    PubMed

    Jean, Cyril; Belliard, Laurent; Cornelius, Thomas W; Thomas, Olivier; Toimil-Molares, Maria Eugenia; Cassinelli, Marco; Becerra, Loïc; Perrin, Bernard

    2014-12-01

    We report on gigahertz acoustic phonon waveguiding in free-standing single copper nanowires studied by femtosecond transient reflectivity measurements. The results are discussed on the basis of the semianalytical resolution of the Pochhammer and Chree equation. The spreading of the generated Gaussian wave packet of two different modes is derived analytically and compared with the observed oscillations of the sample reflectivity. These experiments provide a unique way to independently obtain geometrical and material characterization. This direct observation of coherent guided acoustic phonons in a single nano-object is also the first step toward nanolateral size acoustic transducer and comprehensive studies of the thermal properties of nanowires. PMID:26278939

  11. Direct observation of charge mediated lattice distortions in complex oxide solid solutions

    SciTech Connect

    Sang, Xiahan; Grimley, Everett D.; Niu, Changning; Irving, Douglas L.; LeBeau, James M.

    2015-02-09

    Using aberration corrected scanning transmission electron microscopy combined with advanced imaging methods, we directly observe atom column specific, picometer-scale displacements induced by local chemistry in a complex oxide solid solution. Displacements predicted from density functional theory were found to correlate with the observed experimental trends. Further analysis of bonding and charge distribution was used to clarify the mechanisms responsible for the detected structural behavior. By extending the experimental electron microscopy measurements to previously inaccessible length scales, we identified correlated atomic displacements linked to bond differences within the complex oxide structure.

  12. Direct time-domain observation of laser pulse filaments in transparent media

    SciTech Connect

    Dachraoui, H.; Oberer, C.; Michelswirth,; Heinzmann, U.

    2010-10-15

    The interplay among self-focusing, energy depletion, and plasma formation is fundamental to the understanding of laser-matter interaction. In this article, we present the first direct time-resolved observations of the propagation of intense femtosecond laser pulses experiencing conical emission, self-focusing, self-guiding, beam filamentation, plasma defocusing, and continuum generation in wide-band-gap dielectrics. We demonstrate that continuum generation involves different mechanisms as a function of deposited energy.

  13. Controllability and observability analysis for vertex domination centrality in directed networks

    NASA Astrophysics Data System (ADS)

    Wang, Bingbo; Gao, Lin; Gao, Yong; Deng, Yue; Wang, Yu

    2014-06-01

    Topological centrality is a significant measure for characterising the relative importance of a node in a complex network. For directed networks that model dynamic processes, however, it is of more practical importance to quantify a vertex's ability to dominate (control or observe) the state of other vertices. In this paper, based on the determination of controllable and observable subspaces under the global minimum-cost condition, we introduce a novel direction-specific index, domination centrality, to assess the intervention capabilities of vertices in a directed network. Statistical studies demonstrate that the domination centrality is, to a great extent, encoded by the underlying network's degree distribution and that most network positions through which one can intervene in a system are vertices with high domination centrality rather than network hubs. To analyse the interaction and functional dependence between vertices when they are used to dominate a network, we define the domination similarity and detect significant functional modules in glossary and metabolic networks through clustering analysis. The experimental results provide strong evidence that our indices are effective and practical in accurately depicting the structure of directed networks.

  14. Controllability and observability analysis for vertex domination centrality in directed networks.

    PubMed

    Wang, Bingbo; Gao, Lin; Gao, Yong; Deng, Yue; Wang, Yu

    2014-01-01

    Topological centrality is a significant measure for characterising the relative importance of a node in a complex network. For directed networks that model dynamic processes, however, it is of more practical importance to quantify a vertex's ability to dominate (control or observe) the state of other vertices. In this paper, based on the determination of controllable and observable subspaces under the global minimum-cost condition, we introduce a novel direction-specific index, domination centrality, to assess the intervention capabilities of vertices in a directed network. Statistical studies demonstrate that the domination centrality is, to a great extent, encoded by the underlying network's degree distribution and that most network positions through which one can intervene in a system are vertices with high domination centrality rather than network hubs. To analyse the interaction and functional dependence between vertices when they are used to dominate a network, we define the domination similarity and detect significant functional modules in glossary and metabolic networks through clustering analysis. The experimental results provide strong evidence that our indices are effective and practical in accurately depicting the structure of directed networks. PMID:24954137

  15. Warming experiments elucidate the drivers of observed directional changes in tundra vegetation

    PubMed Central

    Hollister, Robert D; May, Jeremy L; Kremers, Kelseyann S; Tweedie, Craig E; Oberbauer, Steven F; Liebig, Jennifer A; Botting, Timothy F; Barrett, Robert T; Gregory, Jessica L

    2015-01-01

    Few studies have clearly linked long-term monitoring with in situ experiments to clarify potential drivers of observed change at a given site. This is especially necessary when findings from a site are applied to a much broader geographic area. Here, we document vegetation change at Barrow and Atqasuk, Alaska, occurring naturally and due to experimental warming over nearly two decades. An examination of plant cover, canopy height, and community indices showed more significant differences between years than due to experimental warming. However, changes with warming were more consistent than changes between years and were cumulative in many cases. Most cases of directional change observed in the control plots over time corresponded with a directional change in response to experimental warming. These included increases in canopy height and decreases in lichen cover. Experimental warming resulted in additional increases in evergreen shrub cover and decreases in diversity and bryophyte cover. This study suggests that the directional changes occurring at the sites are primarily due to warming and indicates that further changes are likely in the next two decades if the regional warming trend continues. These findings provide an example of the utility of coupling in situ experiments with long-term monitoring to accurately document vegetation change in response to global change and to identify the underlying mechanisms driving observed changes. PMID:26140204

  16. Does prey size matter? Novel observations of feeding in the leatherback turtle (Dermochelys coriacea) allow a test of predator-prey size relationships.

    PubMed

    Fossette, Sabrina; Gleiss, Adrian C; Casey, James P; Lewis, Andrew R; Hays, Graeme C

    2012-06-23

    Optimal foraging models predict that large predators should concentrate on large prey in order to maximize their net gain of energy intake. Here, we show that the largest species of sea turtle, Dermochelys coriacea, does not strictly adhere to this general pattern. Field observations combined with a theoretical model suggest that a 300 kg leatherback turtle would meet its energetic requirements by feeding for 3-4 h a day on 4 g jellyfish, but only if prey were aggregated in high-density patches. Therefore, prey abundance rather than prey size may, in some cases, be the overriding parameter for foraging leatherbacks. This is a classic example where the presence of small prey in the diet of a large marine predator may reflect profitable foraging decisions if the relatively low energy intake per small individual prey is offset by high encounter rates and minimal capture and handling costs. This study provides, to our knowledge, the first quantitative estimates of intake rate for this species. PMID:22090203

  17. Does prey size matter? Novel observations of feeding in the leatherback turtle (Dermochelys coriacea) allow a test of predator–prey size relationships

    PubMed Central

    Fossette, Sabrina; Gleiss, Adrian C.; Casey, James P.; Lewis, Andrew R.; Hays, Graeme C.

    2012-01-01

    Optimal foraging models predict that large predators should concentrate on large prey in order to maximize their net gain of energy intake. Here, we show that the largest species of sea turtle, Dermochelys coriacea, does not strictly adhere to this general pattern. Field observations combined with a theoretical model suggest that a 300 kg leatherback turtle would meet its energetic requirements by feeding for 3–4 h a day on 4 g jellyfish, but only if prey were aggregated in high-density patches. Therefore, prey abundance rather than prey size may, in some cases, be the overriding parameter for foraging leatherbacks. This is a classic example where the presence of small prey in the diet of a large marine predator may reflect profitable foraging decisions if the relatively low energy intake per small individual prey is offset by high encounter rates and minimal capture and handling costs. This study provides, to our knowledge, the first quantitative estimates of intake rate for this species. PMID:22090203

  18. Direct observation of imprinted antiferromagnetic vortex state in CoO/Fe/Ag(001) disks

    SciTech Connect

    Wu, J.; Carlton, D.; Park, J. S.; Meng, Y.; Arenholz, E.; Doran, A.; Young, A.T.; Scholl, A.; Hwang, C.; Zhao, H. W.; Bokor, J.; Qiu, Z. Q.

    2010-12-21

    In magnetic thin films, a magnetic vortex is a state in which the magnetization vector curls around the center of a confined structure. A vortex state in a thin film disk, for example, is a topological object characterized by the vortex polarity and the winding number. In ferromagnetic (FM) disks, these parameters govern many fundamental properties of the vortex such as its gyroscopic rotation, polarity reversal, core motion, and vortex pair excitation. However, in antiferromagnetic (AFM) disks, though there has been indirect evidence of the vortex state through observations of the induced FM-ordered spins in the AFM disk, they have never been observed directly in experiment. By fabricating single crystalline NiO/Fe/Ag(001) and CoO/Fe/Ag(001) disks and using X-ray Magnetic Linear Dichroism (XMLD), we show direct observation of the vortex state in an AFM disk of AFM/FM bilayer system. We observe that there are two types of AFM vortices, one of which has no analog in FM structures. Finally, we show that a frozen AFM vortex can bias a FM vortex at low temperature.

  19. Home Videophones Improve Direct Observation in Tuberculosis Treatment: A Mixed Methods Evaluation

    PubMed Central

    Wade, Victoria A.; Karnon, Jonathan; Eliott, Jaklin A.; Hiller, Janet E.

    2012-01-01

    Background The use of direct observation to monitor tuberculosis treatment is controversial: cost, practical difficulties, and lack of patient acceptability limit effectiveness. Telehealth is a promising alternative delivery method for improving implementation. This study aimed to evaluate the clinical and cost-effectiveness of a telehealth service delivering direct observation, compared to an in-person drive-around service. Methodology/Principal Findings The study was conducted within a community nursing service in South Australia. Telehealth patients received daily video calls at home on a desktop videophone provided by the nursing call center. A retrospective cohort study assessed the effectiveness of the telehealth and traditional forms of observation, defined by the proportion of missed observations recorded in case notes. This data was inputted to a model, estimating the incremental cost-effectiveness ratio (ICER) of telehealth. Semi-structured interviews were conducted with current patients, community nursing and Chest Clinic staff, concerning service acceptability, usability and sustainability. The percentage of missed observations for the telehealth service was 12.1 (n = 58), compared to 31.1 for the in-person service (n = 70). Most of the difference of 18.9% (95% CI: 12.2 – 25.4) was due to fewer pre-arranged absences. The economic analysis calculated the ICER to be AUD$1.32 (95% CI: $0.51 – $2.26) per extra day of successful observation. The video service used less staff time, and became dominant if implemented on a larger scale and/or with decreased technology costs. Qualitative analysis found enabling factors of flexible timing, high patient acceptance, staff efficiency, and Chest Clinic support. Substantial technical problems were manageable, and improved liaison between the nursing service and Chest Clinic was an unexpected side-benefit. Conclusions/Significance Home video observation is a patient-centered, resource efficient way of

  20. Direct observation of Li diffusion in Li-doped ZnO nanowires

    NASA Astrophysics Data System (ADS)

    Li, Guohua; Yu, Lei; Hudak, Bethany M.; Chang, Yao-Jen; Baek, Hyeonjun; Sundararajan, Abhishek; Strachan, Douglas R.; Yi, Gyu-Chul; Guiton, Beth S.

    2016-05-01

    The direct observation of Li diffusion in Li-doped zinc oxide nanowires (NWs) was realized by using in situ heating in the scanning transmission electron microscope (STEM). A continuous increase of low atomic mass regions within a single NW was observed between 200 °C and 600 °C when heated in vacuum, which was explained by the conversion of interstitial to substitutional Li in the ZnO NW host lattice. A kick-out mechanism is introduced to explain the migration and conversion of the interstitial Li (Lii) to Zn-site substitutional Li (LiZn), and this mechanism is verified with low-temperature (11 K) photoluminescence measurements on as-grown and annealed Li-doped zinc oxide NWs, as well as the observation of an increase of NW surface roughing with applied bias.

  1. Direct observation and quantification of extracellular long-range electron flow in anaerobic bacteria

    NASA Astrophysics Data System (ADS)

    Malvankar, Nikhil; Yalcin, Sibel; Vargas, Madeline; Tuominen, Mark; Lovley, Derek

    2013-03-01

    Some anaerobic microorganisms are capable of transporting electrons outside their cell to distant electron acceptors such as metals, minerals or partner species. Previous studies have focused primarily on transport over short distances (< 1 μm) via diffusion of molecular intermediates, or alternatively via tunneling or thermally-activated hopping across biomolecules. However, we have found that Geobacter sulfurreducens can transport electrons over long distances (> 10 μm) using pili filaments that show organic metal-like conductivity. Pili also enable direct exchange of electrons among syntrophic Geobacter co-cultures. In order to establish the physical principles underlying this remarkable electron transport, we have employed a novel scanning probe microscopy-based method to perform quantitative measurements of electron flow at a single cell level under physiological conditions. Using this nanoscopic approach, we have directly observed the propagation and distribution of injected electrons in individual native bacterial extracellular proteins. Our direct measurements demonstrate unambiguously for the first time that the pili of G. sulfurreducens are a novel class of electronically functional proteins that can sustain electron flow in a surprising manner that has not been observed previously in any other natural protein. Funded by Office of Naval Research, DOE Genomic Sciences and NSF-NSEC Center for Hierarchical Manufacturing grant no. CMMI-1025020.

  2. Investigating common clinical presentations in first opinion small animal consultations using direct observation

    PubMed Central

    Robinson, N. J.; Dean, R. S.; Cobb, M.; Brennan, M. L.

    2015-01-01

    Understanding more about the clinical presentations encountered in veterinary practice is vital in directing research towards areas relevant to practitioners. The aim of this study was to describe all problems discussed during a convenience sample of consultations using a direct observation method. A data collection tool was used to gather data by direct observation during small animal consultations at eight sentinel practices. Data were recorded for all presenting and non-presenting specific health problems discussed. A total of 1901 patients were presented with 3206 specific health problems discussed. Clinical presentation varied widely between species and between presenting and non-presenting problems. Skin lump, vomiting and inappetence were the most common clinical signs reported by the owner while overweight/obese, dental tartar and skin lump were the most common clinical examination findings. Skin was the most frequently affected body system overall followed by non-specific problems then the gastrointestinal system. Consultations are complex, with a diverse range of different clinical presentations seen. Considering the presenting problem only may give an inaccurate view of the veterinary caseload, as some common problems are rarely the reason for presentation. Understanding the common diagnoses made is the next step and will help to further focus questions for future research. PMID:25564472

  3. An accuracy measurement method for star trackers based on direct astronomic observation

    NASA Astrophysics Data System (ADS)

    Sun, Ting; Xing, Fei; Wang, Xiaochu; You, Zheng; Chu, Daping

    2016-03-01

    Star tracker is one of the most promising optical attitude measurement devices and it is widely used in spacecraft for its high accuracy. However, how to realize and verify such an accuracy remains a crucial but unsolved issue until now. The authenticity of the accuracy measurement method of a star tracker will eventually determine the satellite performance. A new and robust accuracy measurement method for a star tracker based on the direct astronomical observation is proposed here. In comparison with the conventional method with simulated stars, this method utilizes real navigation stars as observation targets which makes the measurement results more authoritative and authentic. Transformations between different coordinate systems are conducted on the account of the precision movements of the Earth, and the error curves of directional vectors are obtained along the three axes. Based on error analysis and accuracy definitions, a three-axis accuracy evaluation criterion has been proposed in this paper, which could determine pointing and rolling accuracy of a star tracker directly. Experimental measurements confirm that this method is effective and convenient to implement. Such a measurement environment is close to the in-orbit conditions and it can satisfy the stringent requirement for high-accuracy star trackers.

  4. An accuracy measurement method for star trackers based on direct astronomic observation

    PubMed Central

    Sun, Ting; Xing, Fei; Wang, Xiaochu; You, Zheng; Chu, Daping

    2016-01-01

    Star tracker is one of the most promising optical attitude measurement devices and it is widely used in spacecraft for its high accuracy. However, how to realize and verify such an accuracy remains a crucial but unsolved issue until now. The authenticity of the accuracy measurement method of a star tracker will eventually determine the satellite performance. A new and robust accuracy measurement method for a star tracker based on the direct astronomical observation is proposed here. In comparison with the conventional method with simulated stars, this method utilizes real navigation stars as observation targets which makes the measurement results more authoritative and authentic. Transformations between different coordinate systems are conducted on the account of the precision movements of the Earth, and the error curves of directional vectors are obtained along the three axes. Based on error analysis and accuracy definitions, a three-axis accuracy evaluation criterion has been proposed in this paper, which could determine pointing and rolling accuracy of a star tracker directly. Experimental measurements confirm that this method is effective and convenient to implement. Such a measurement environment is close to the in-orbit conditions and it can satisfy the stringent requirement for high-accuracy star trackers. PMID:26948412

  5. An accuracy measurement method for star trackers based on direct astronomic observation.

    PubMed

    Sun, Ting; Xing, Fei; Wang, Xiaochu; You, Zheng; Chu, Daping

    2016-01-01

    Star tracker is one of the most promising optical attitude measurement devices and it is widely used in spacecraft for its high accuracy. However, how to realize and verify such an accuracy remains a crucial but unsolved issue until now. The authenticity of the accuracy measurement method of a star tracker will eventually determine the satellite performance. A new and robust accuracy measurement method for a star tracker based on the direct astronomical observation is proposed here. In comparison with the conventional method with simulated stars, this method utilizes real navigation stars as observation targets which makes the measurement results more authoritative and authentic. Transformations between different coordinate systems are conducted on the account of the precision movements of the Earth, and the error curves of directional vectors are obtained along the three axes. Based on error analysis and accuracy definitions, a three-axis accuracy evaluation criterion has been proposed in this paper, which could determine pointing and rolling accuracy of a star tracker directly. Experimental measurements confirm that this method is effective and convenient to implement. Such a measurement environment is close to the in-orbit conditions and it can satisfy the stringent requirement for high-accuracy star trackers. PMID:26948412

  6. An improved microscope stage for direct observation of freezing and freeze drying.

    PubMed

    Nail, S L; Her, L M; Proffitt, C P; Nail, L L

    1994-08-01

    A microscope stage for observation of freezing and freeze drying is described. The stage uses thermoelectric (Peltier) heaters configured in two stages, with circulating fluid as a heat sink on the high temperature side. Lowest attainable sample temperature is about -47 degrees C. Principal advantages of this system are closed-loop control of stage temperature, rapid response to changes in temperature set point, and improved documentation of experiments by use of a video recorder system with a character generator which allows display of sample identity and temperature. Accuracy of measuring the sample temperature in the field of view was validated by comparing observed values of eutectic melting with published values for a series of solutes with eutectic temperatures in the range from -2 degrees C to -32 degrees C. Good agreement was obtained throughout this range. PMID:7971708

  7. Direct observation of ionic structure at solid-liquid interfaces: a deep look into the Stern Layer

    PubMed Central

    Siretanu, Igor; Ebeling, Daniel; Andersson, Martin P.; Stipp, S. L. Svane; Philipse, Albert; Stuart, Martien Cohen; van den Ende, Dirk; Mugele, Frieder

    2014-01-01

    The distribution of ions and charge at solid-water interfaces plays an essential role in a wide range of processes in biology, geology and technology. While theoretical models of the solid-electrolyte interface date back to the early 20th century, a detailed picture of the structure of the electric double layer has remained elusive, largely because of experimental techniques have not allowed direct observation of the behaviour of ions, i.e. with subnanometer resolution. We have made use of recent advances in high-resolution Atomic Force Microscopy to reveal, with atomic level precision, the ordered adsorption of the mono- and divalent ions that are common in natural environments to heterogeneous gibbsite/silica surfaces in contact with aqueous electrolytes. Complemented by density functional theory, our experiments produce a detailed picture of the formation of surface phases by templated adsorption of cations, anions and water, stabilized by hydrogen bonding. PMID:24850566

  8. A Multimethod Study of Problem Behavior among Thai and American Children in School: Teacher Reports versus Direct Observations.

    ERIC Educational Resources Information Center

    Weisz, John R.; And Others

    1995-01-01

    Trained observers conducted direct observations of Thai and American children's school behavior and obtained teacher reports on the same children. Observers reported twice as much problem behavior and off-task behavior in American children as in their Thai age-mates, contradicting some earlier studies. Findings support the value of direct behavior…

  9. Increasing Reliability of Direct Observation Measurement Approaches in Emotional and/or Behavioral Disorders Research Using Generalizability Theory

    ERIC Educational Resources Information Center

    Gage, Nicholas A.; Prykanowski, Debra; Hirn, Regina

    2014-01-01

    Reliability of direct observation outcomes ensures the results are consistent, dependable, and trustworthy. Typically, reliability of direct observation measurement approaches is assessed using interobserver agreement (IOA) and the calculation of observer agreement (e.g., percentage of agreement). However, IOA does not address intraobserver…

  10. Apparatus for Direct Optical Fiber Through-Lens Illumination of Microscopy or Observational Objects

    NASA Technical Reports Server (NTRS)

    Kadogawa, Hiroshi (Inventor)

    2001-01-01

    In one embodiment of the invention, a microscope or other observational apparatus, comprises a hollow tube, a lens mounted to the tube, a light source and at least one flexible optical fiber having an input end and an output end. The input end is positioned to receive light from the light source, and the output end is positioned within the tube so as to directly project light along a straight path to the lens to illuminate an object to be viewed. The path of projected light is uninterrupted and free of light deflecting elements. By passing the light through the lens, the light can be diffused or otherwise defocused to provide more uniform illumination across the surface of the object, increasing the quality of the image of the object seen by the viewer. The direct undeflected and uninterrupted projection of light, without change of direction, eliminates the need for light-deflecting elements, such as beam-splitters, mirrors, prisms, or the like, to direct the projected light towards the object.

  11. Direct laboratory observation of fluid distribution and its influence on acoustic properties of patchy saturated rocks

    NASA Astrophysics Data System (ADS)

    Lebedev, M.; Clennell, B.; Pervukhina, M.; Shulakova, V.; Mueller, T.; Gurevich, B.

    2009-04-01

    samples (38 mm in diameter, approximately 60 mm long) were dried in oven under reduced pressure. In dynamic saturation experiments, samples were jacketed in the experimental cell, made from transparent for X-radiation material (PMMA). Distillate water was injected into the sample from the one side. Fluid distribution in such "dynamic" experiment: both spatial and time dependant was measured using X-ray Computer Tomograph (CT) with resolution 0.2 x 0.2 x 1 mm3. Velocities (Vp, and Vs) at ultrasonic frequency of 1 MHz, were measured in the direction perpendicular to initial direction of the fluid flow injection. Sample saturation was estimated from the CT results. In "quasi static" experiments samples were saturated during long period of time (over 2 weeks) to achieve uniform distribution of liquid inside the sample. Saturation was determined by measurement of the weight of water fraction. All experiments were performed at laboratory environments at temperature 25 C. Ultrasonic velocities and fluid saturations were measured simultaneously during water injection into sandstone core samples. The experimental results obtained on low-permeability samples show that at low saturation values the velocity-saturation dependence can be described by the Gassmann-Wood relationship. However, with increasing saturation a sharp increase of P-wave velocity is observed, eventually approaching the Gassmann-Hill relationship. We connect the characteristics of the transition behavior of the velocity-saturation relationships to the increasing size of the patches inside the rock sample. In particular, we show that for relatively large fluid injection rate this transition occurs at smaller degrees of saturation as compared with high injection rate. We model the experimental data using the so-called White model (Toms 2007) that assumes fluid patch distribution as a periodic assemblage of concentric spheres. We can observe reasonable agreement between experimental results and theoretical

  12. Direct Observation of Aggregative Nanoparticle Growth: Kinetic Modeling of the Size Distribution and Growth Rate

    SciTech Connect

    Woehl, Taylor J.; Park, Chiwoo; Evans, James E.; Arslan, Ilke; Ristenpart, William D.; Browning, Nigel D.

    2014-01-08

    Direct observations of solution-phase nanoparticle growth using in situ liquid transmission electron microscopy (TEM) have demonstrated the importance of “non-classical” growth mechanisms, such as aggregation and coalescence, on the growth and final morphology of nanocrystals at the atomic and single nanoparticle scales. To date, groups have quantitatively interpreted the mean growth rate of nanoparticles in terms of the Lifshitz-Slyozov-Wagner (LSW) model for Ostwald ripening, but less attention has been paid to modeling the corresponding particle size distribution. Here we use in situ fluid stage scanning TEM to demonstrate that silver nanoparticles grow by a length-scale dependent mechanism, where individual nanoparticles grow by monomer attachment but ensemble-scale growth is dominated by aggregation. Although our observed mean nanoparticle growth rate is consistent with the LSW model, we show that the corresponding particle size distribution is broader and more symmetric than predicted by LSW. Following direct observations of aggregation, we interpret the ensemble-scale growth using Smoluchowski kinetics and demonstrate that the Smoluchowski model quantitatively captures the mean growth rate and particle size distribution.

  13. Direct Observation of Chiral Topological Solitons in 1D Charge-Density Waves

    NASA Astrophysics Data System (ADS)

    Kim, Tae-Hwan; Cheon, Sangmo; Lee, Sung-Hoon; Yeom, Han Woong

    2015-03-01

    Macroscopic and classical solitons are easily and ubiquitously found, from tsunami to blood pressure pulses, but those in microscopic scale are hard to observe. While the existence of such topological solitons were predicted theoretically and evidenced indirectly by the transport and infrared spectroscopy measurements, the direct observation has been hampered by their high mobility and small dimension. In this talk, we show direct observation of topological solitons in the quasi-1D charge-density wave (CDW) ground state of indium atomic wires, which are consisting of interacting double Peierls chains. Such solitons exhibit a characteristic spatial variation of the CDW amplitudes as expected from the electronic structure. Furthermore, these solitons have an exotic hidden topology originated by topologically different 4-fold degenerate CDW ground states. Their exotic topology leads to the chirality of 1D topological solitons through interaction between two solitons in the double Peierls chains. Detailed scanning tunneling microscopy and spectroscopy reveal their chiral nature at the atomic scale. This work paves the avenue toward the microscopic exploitation of the peculiar properties of nanoscale chiral solitons.

  14. Direct Observation of Wet Biological Samples by Graphene Liquid Cell Transmission Electron Microscopy.

    PubMed

    Park, Jungwon; Park, Hyesung; Ercius, Peter; Pegoraro, Adrian F; Xu, Chen; Kim, Jin Woong; Han, Sang Hoon; Weitz, David A

    2015-07-01

    Recent development of liquid phase transmission electron microscopy (TEM) enables the study of specimens in wet ambient conditions within a liquid cell; however, direct structural observation of biological samples in their native solution using TEM is challenging since low-mass biomaterials embedded in a thick liquid layer of the host cell demonstrate low contrast. Furthermore, the integrity of delicate wet samples is easily compromised during typical sample preparation and TEM imaging. To overcome these limitations, we introduce a graphene liquid cell (GLC) using multilayer graphene sheets to reliably encapsulate and preserve biological samples in a liquid for TEM observation. We achieve nanometer scale spatial resolution with high contrast using low-dose TEM at room temperature, and we use the GLC to directly observe the structure of influenza viruses in their native buffer solution at room temperature. The GLC is further extended to investigate whole cells in wet conditions using TEM. We also demonstrate the potential of the GLC for correlative studies by TEM and fluorescence light microscopy imaging. PMID:26065925

  15. Direct observations of microscale turbulence and thermohaline structure in the Kuroshio Front

    NASA Astrophysics Data System (ADS)

    Nagai, Takeyoshi; Tandon, Amit; Yamazaki, Hidekatsu; Doubell, Mark J.; Gallager, Scott

    Direct observations of microstructure near the Kuroshio Front were conducted in August 2008 and October 2009. These show negative potential vorticity (PV) in the mixed layer south of the front, where directly measured turbulent kinetic energy dissipation rates are an order magnitude larger than predicted by wind-scaling. These elevated dissipation rates scale better with an empirical scaling, which considers local wind and Ekman buoyancy flux driven by downfront wind. Near-zero PV in the thermocline under the Kuroshio mainstream is observed at 200-300 m depth, with dissipation exceeding open ocean thermocline values by factors of 10-100. Overall, the large turbulent dissipation rates measured in the Kuroshio can be categorized into two groups, one characterized by low Richardson number along the Kuroshio Front thermocline, and the other characterized by high stratification away from the Kuroshio mainstream. The former is attributed to mixing by unbalanced frontal ageostrophic flows, and the latter is attributed to internal wave breaking. On average, both groups appear in regions of large horizontal density gradients. Observed thermohaline structure shows low salinity tongues from the surface to over 300 m depth and deep cold tongues, extending upward from 500 to 100 m depth in a narrow (20 km) zone, suggesting down and upwelling driven by geostrophic straining, which is confirmed by Quasigeostrophic-Omega equation solutions. This implies that adiabatic along isopycnal subduction and diabatic diapycnal turbulent mixing acting in tandem at the Kuroshio Front likely contribute to NPIW formation.

  16. Direct observation of the nucleation in colloidal solid-solid transitions

    NASA Astrophysics Data System (ADS)

    Peng, Yi; Wang, Feng; Wang, Ziren; Han, Yilong

    2013-03-01

    Solid-solid phase transitions are ubiquitous in nature, but their microscopic mechanisms remain poorly understood. We employed thermally sensitive microgels to study the solid-solid transitions between square and triangular lattices in colloidal thin films. Two types of nucleation processes were directly observed by video microscopy and studied at the single-particle level. Under low flow rates, the nucleation is a two-step process: square lattice --> liquid nucleus --> triangle nucleus and its precursor is a local particle-exchange loop, whereas under high flow rates the nucleus of the triangle lattice forms directly from a dislocation pair by a martensitic mechanism. We measured the critical nucleus size, the energy barrier height and the hysteresis loop of the solid-solid transitions. Our results cast new light to solid-solid transitions in carbon systems, nano-crystals and geophysics. Hong Kong GRC grants 601208 and 601911

  17. Direct observation of a highly spin-polarized organic spinterface at room temperature

    PubMed Central

    Djeghloul, F.; Ibrahim, F.; Cantoni, M.; Bowen, M.; Joly, L.; Boukari, S.; Ohresser, P.; Bertran, F.; Le Fèvre, P.; Thakur, P.; Scheurer, F.; Miyamachi, T.; Mattana, R.; Seneor, P.; Jaafar, A.; Rinaldi, C.; Javaid, S.; Arabski, J.; Kappler, J. -P; Wulfhekel, W.; Brookes, N. B.; Bertacco, R.; Taleb-Ibrahimi, A.; Alouani, M.; Beaurepaire, E.; Weber, W.

    2013-01-01

    Organic semiconductors constitute promising candidates toward large-scale electronic circuits that are entirely spintronics-driven. Toward this goal, tunneling magnetoresistance values above 300% at low temperature suggested the presence of highly spin-polarized device interfaces. However, such spinterfaces have not been observed directly, let alone at room temperature. Thanks to experiments and theory on the model spinterface between phthalocyanine molecules and a Co single crystal surface, we clearly evidence a highly efficient spinterface. Spin-polarised direct and inverse photoemission experiments reveal a high degree of spin polarisation at room temperature at this interface. We measured a magnetic moment on the molecule's nitrogen π orbitals, which substantiates an ab-initio theoretical description of highly spin-polarised charge conduction across the interface due to differing spinterface formation mechanisms in each spin channel. We propose, through this example, a recipe to engineer simple organic-inorganic interfaces with remarkable spintronic properties that can endure well above room temperature. PMID:23412079

  18. Direct assessment of groundwater vulnerability from single observations of multiple contaminants

    USGS Publications Warehouse

    Worrall, F.; Kolpin, D.W.

    2003-01-01

    Groundwater vulnerability is a central concept in pollution risk assessment, yet its estimation has been largely a matter of expert judgment. This work applies a method for the direct calculation of vulnerability from monitoring well observations of pesticide concentrations. The method has two major advantages: it is independent of the compounds being examined, and it has a direct probabilistic interpretation making it ideal for risk assessment. The methodology was applied to data from a groundwater monitoring program in the midwestern United States. The distribution of the vulnerabilities was skewed toward zero. Spatial distribution of the vulnerabilities shows them to be controlled by both regional and local factors. Methods are presented for estimating the necessary sample sizes for vulnerability studies. The further application of the approach developed in this study to understanding groundwater pollution is discussed.

  19. Photoacoustics of single laser-trapped nanodroplets for the direct observation of nanofocusing in aerosol photokinetics

    NASA Astrophysics Data System (ADS)

    Cremer, Johannes W.; Thaler, Klemens M.; Haisch, Christoph; Signorell, Ruth

    2016-03-01

    Photochemistry taking place in atmospheric aerosol droplets has a significant impact on the Earth's climate. Nanofocusing of electromagnetic radiation inside aerosols plays a crucial role in their absorption behaviour, since the radiation flux inside the droplet strongly affects the activation rate of photochemically active species. However, size-dependent nanofocusing effects in the photokinetics of small aerosols have escaped direct observation due to the inability to measure absorption signatures from single droplets. Here we show that photoacoustic measurements on optically trapped single nanodroplets provide a direct, broadly applicable method to measure absorption with attolitre sensitivity. We demonstrate for a model aerosol that the photolysis is accelerated by an order of magnitude in the sub-micron to micron size range, compared with larger droplets. The versatility of our technique promises broad applicability to absorption studies of aerosol particles, such as atmospheric aerosols where quantitative photokinetic data are critical for climate predictions.

  20. Photoacoustics of single laser-trapped nanodroplets for the direct observation of nanofocusing in aerosol photokinetics.

    PubMed

    Cremer, Johannes W; Thaler, Klemens M; Haisch, Christoph; Signorell, Ruth

    2016-01-01

    Photochemistry taking place in atmospheric aerosol droplets has a significant impact on the Earth's climate. Nanofocusing of electromagnetic radiation inside aerosols plays a crucial role in their absorption behaviour, since the radiation flux inside the droplet strongly affects the activation rate of photochemically active species. However, size-dependent nanofocusing effects in the photokinetics of small aerosols have escaped direct observation due to the inability to measure absorption signatures from single droplets. Here we show that photoacoustic measurements on optically trapped single nanodroplets provide a direct, broadly applicable method to measure absorption with attolitre sensitivity. We demonstrate for a model aerosol that the photolysis is accelerated by an order of magnitude in the sub-micron to micron size range, compared with larger droplets. The versatility of our technique promises broad applicability to absorption studies of aerosol particles, such as atmospheric aerosols where quantitative photokinetic data are critical for climate predictions. PMID:26979973

  1. Direct observation of spin-orbit coupling in iron-based superconductors

    NASA Astrophysics Data System (ADS)

    Borisenko, S. V.; Evtushinsky, D. V.; Liu, Z.-H.; Morozov, I.; Kappenberger, R.; Wurmehl, S.; Büchner, B.; Yaresko, A. N.; Kim, T. K.; Hoesch, M.; Wolf, T.; Zhigadlo, N. D.

    2016-04-01

    Spin-orbit coupling is a fundamental interaction in solids that can induce a broad range of unusual physical properties, from topologically non-trivial insulating states to unconventional pairing in superconductors. In iron-based superconductors its role has, so far, not been considered of primary importance, with models based on spin- or orbital fluctuations pairing being used most widely. Using angle-resolved photoemission spectroscopy, we directly observe a sizeable spin-orbit splitting in all the main members of the iron-based superconductors. We demonstrate that its impact on the low-energy electronic structure and details of the Fermi surface topology is stronger than that of possible nematic ordering. The largest pairing gap is supported exactly by spin-orbit-coupling-induced Fermi surfaces, implying a direct relation between this interaction and the mechanism of high-temperature superconductivity.

  2. Technique to observe direct CP violation in D mesons using Bose symmetry and the Dalitz plot

    NASA Astrophysics Data System (ADS)

    Sahoo, Dibyakrupa; Sinha, Rahul; Deshpande, N. G.; Pakvasa, Sandip

    2014-04-01

    We present a new method to observe direct CP violation in D mesons using Bose symmetry and the Dalitz plot. We apply the method to processes such as B→D0D¯0P, where P is either a K or a π. By choosing to reconstruct D mesons only through their decays into CP eigenstates, we show that any asymmetry in the Dalitz plot can arise only through direct CP violation. We further show how CP violation parameters can be determined. Since the approach involves only Bose symmetry, the method is applicable to any multibody process that involves D0D¯0 in the final state. We briefly discuss how B→D*D¯*P can also be used in a similar way. This method can also be applied to D0D¯0 in the final state from continuum cc¯ production.

  3. Direct observation of a propagating spin wave induced by spin-transfer torque.

    PubMed

    Madami, M; Bonetti, S; Consolo, G; Tacchi, S; Carlotti, G; Gubbiotti, G; Mancoff, F B; Yar, M A; Akerman, J

    2011-10-01

    Spin torque oscillators with nanoscale electrical contacts are able to produce coherent spin waves in extended magnetic films, and offer an attractive combination of electrical and magnetic field control, broadband operation, fast spin-wave frequency modulation, and the possibility of synchronizing multiple spin-wave injection sites. However, many potential applications rely on propagating (as opposed to localized) spin waves, and direct evidence for propagation has been lacking. Here, we directly observe a propagating spin wave launched from a spin torque oscillator with a nanoscale electrical contact into an extended Permalloy (nickel iron) film through the spin transfer torque effect. The data, obtained by wave-vector-resolved micro-focused Brillouin light scattering, show that spin waves with tunable frequencies can propagate for several micrometres. Micromagnetic simulations provide the theoretical support to quantitatively reproduce the results. PMID:21873993

  4. The effect of stopping before turning on the direct observational measure of whole body turning bias.

    PubMed

    Taylor, M J D; Strike, S C

    2016-06-01

    Turning bias, the preferential tendency to turn toward a given direction has been reported in both rodents and human participants. The observational gait method of determining turning bias in humans requires a stop prior to turning. This study removed the stop and hypothesised that turning bias would remain the same between stop and non-stop conditions if bias was solely under the control of neurochemical asymmetries. The results showed that statistically turning bias remained the same (to the left) regardless of method used but there was no agreement between the methods thus rejecting the hypothesis. It is likely that when not stopping biomechanical factors related to gait when turning influence the direction of turn rather than solely neurochemical asymmetries. PMID:26974038

  5. Photoacoustics of single laser-trapped nanodroplets for the direct observation of nanofocusing in aerosol photokinetics

    PubMed Central

    Cremer, Johannes W.; Thaler, Klemens M.; Haisch, Christoph; Signorell, Ruth

    2016-01-01

    Photochemistry taking place in atmospheric aerosol droplets has a significant impact on the Earth's climate. Nanofocusing of electromagnetic radiation inside aerosols plays a crucial role in their absorption behaviour, since the radiation flux inside the droplet strongly affects the activation rate of photochemically active species. However, size-dependent nanofocusing effects in the photokinetics of small aerosols have escaped direct observation due to the inability to measure absorption signatures from single droplets. Here we show that photoacoustic measurements on optically trapped single nanodroplets provide a direct, broadly applicable method to measure absorption with attolitre sensitivity. We demonstrate for a model aerosol that the photolysis is accelerated by an order of magnitude in the sub-micron to micron size range, compared with larger droplets. The versatility of our technique promises broad applicability to absorption studies of aerosol particles, such as atmospheric aerosols where quantitative photokinetic data are critical for climate predictions. PMID:26979973

  6. A Flexible Reporter System for Direct Observation and Isolation of Cancer Stem Cells

    PubMed Central

    Tang, Binwu; Raviv, Asaf; Esposito, Dominic; Flanders, Kathleen C.; Daniel, Catherine; Nghiem, Bao Tram; Garfield, Susan; Lim, Langston; Mannan, Poonam; Robles, Ana I.; Smith, William I.; Zimmerberg, Joshua; Ravin, Rea; Wakefield, Lalage M.

    2014-01-01

    Summary Many tumors are hierarchically organized with a minority cell population that has stem-like properties and enhanced ability to initiate tumorigenesis and drive therapeutic relapse. These cancer stem cells (CSCs) are typically identified by complex combinations of cell-surface markers that differ among tumor types. Here, we developed a flexible lentiviral-based reporter system that allows direct visualization of CSCs based on functional properties. The reporter responds to the core stem cell transcription factors OCT4 and SOX2, with further selectivity and kinetic resolution coming from use of a proteasome-targeting degron. Cancer cells marked by this reporter have the expected properties of self-renewal, generation of heterogeneous offspring, high tumor- and metastasis-initiating activity, and resistance to chemotherapeutics. With this approach, the spatial distribution of CSCs can be assessed in settings that retain microenvironmental and structural cues, and CSC plasticity and response to therapeutics can be monitored in real time. PMID:25497455

  7. Statistical study of muons counts rates in differents directions, observed at the Brazilian Southern Space Observatory

    NASA Astrophysics Data System (ADS)

    Grams, Guilherme; Schuch, Nelson Jorge; Braga, Carlos Roberto; Purushottam Kane, Rajaram; Echer, Ezequiel; Ronan Coelho Stekel, Tardelli

    Cosmic ray are charged particles, at the most time protons, that reach the earth's magne-tosphere from interplanetary space with velocities greater than the solar wind. When these impinge the atmosphere, they interact with atmosphere constituents and decay into sub-particles forming an atmospheric shower. The muons are the sub-particles which normally maintain the originated direction of the primary cosmic ray. A multi-directional muon detec-tor (MMD) was installed in 2001 and upgraded in 2005, through an international cooperation between Brazil, Japan and USA, and operated since then at the Southern Space Observatory -SSO/CRS/CCR/INPE -MCT, (29,4° S, 53,8° W, 480m a.s.l.), São Martinho da Serra, RS, a Brazil. The main objetive of this work is to present a statistical analysis of the intensity of muons, with energy between 50 and 170 GeV, in differents directions, measured by the SSO's multi-directional muon detector. The analysis was performed with data from 2006 and 2007 collected by the SSO's MMD. The MMD consists of two layers of 4x7 detectors with a total observation area of 28 m2 . The counting of muons in each directional channel is made by a coincidence of pulses pair, one from a detector in the upper layer and the other from a detector in the lower layer. The SSO's MMD is equipped with 119 directional channels for muon count rate measurement and is capable of detecting muons incident with zenithal angle between 0° and 75,53° . A statistical analysis was made with the MMD muon count rate for all the di-rectional channels. The average and the standard deviation of the muon count rate in each directional component were calculated. The results show lower cont rate for the channels with larger zenith, and higher cont rate with smaller zenith, as expected from the production and propagation of muons in the atmosphere. It is also possible to identify the Stormer cone. The SSO's MMD is also a detector component of the Global Muon Detector Network (GMDN

  8. Direct observation of protein microcrystals in crystallization buffer by atmospheric scanning electron microscopy.

    PubMed

    Maruyama, Yuusuke; Ebihara, Tatsuhiko; Nishiyama, Hidetoshi; Konyuba, Yuji; Senda, Miki; Numaga-Tomita, Takuro; Senda, Toshiya; Suga, Mitsuo; Sato, Chikara

    2012-01-01

    X-ray crystallography requires high quality crystals above a given size. This requirement not only limits the proteins to be analyzed, but also reduces the speed of the structure determination. Indeed, the tertiary structures of many physiologically important proteins remain elusive because of the so-called "crystallization bottleneck". Once microcrystals have been obtained, crystallization conditions can be optimized to produce bigger and better crystals. However, the identification of microcrystals can be difficult due to the resolution limit of optical microscopy. Electron microscopy has sometimes been utilized instead, with the disadvantage that the microcrystals usually must be observed in vacuum, which precludes the usage for crystal screening. The atmospheric scanning electron microscope (ASEM) allows samples to be observed in solution. Here, we report the use of this instrument in combination with a special thin-membrane dish with a crystallization well. It was possible to observe protein crystals of lysozyme, lipase B and a histone chaperone TAF-Iβ in crystallization buffers, without the use of staining procedures. The smallest crystals observed with ASEM were a few μm in width, and ASEM can be used with non-transparent solutions. Furthermore, the growth of salt crystals could be monitored in the ASEM, and the difference in contrast between salt and protein crystals made it easy to distinguish between these two types of microcrystals. These results indicate that the ASEM could be an important new tool for the screening of protein microcrystals. PMID:22949879

  9. Direct Observation of Protein Microcrystals in Crystallization Buffer by Atmospheric Scanning Electron Microscopy

    PubMed Central

    Maruyama, Yuusuke; Ebihara, Tatsuhiko; Nishiyama, Hidetoshi; Konyuba, Yuji; Senda, Miki; Numaga-Tomita, Takuro; Senda, Toshiya; Suga, Mitsuo; Sato, Chikara

    2012-01-01

    X-ray crystallography requires high quality crystals above a given size. This requirement not only limits the proteins to be analyzed, but also reduces the speed of the structure determination. Indeed, the tertiary structures of many physiologically important proteins remain elusive because of the so-called “crystallization bottleneck”. Once microcrystals have been obtained, crystallization conditions can be optimized to produce bigger and better crystals. However, the identification of microcrystals can be difficult due to the resolution limit of optical microscopy. Electron microscopy has sometimes been utilized instead, with the disadvantage that the microcrystals usually must be observed in vacuum, which precludes the usage for crystal screening. The atmospheric scanning electron microscope (ASEM) allows samples to be observed in solution. Here, we report the use of this instrument in combination with a special thin-membrane dish with a crystallization well. It was possible to observe protein crystals of lysozyme, lipase B and a histone chaperone TAF-Iβ in crystallization buffers, without the use of staining procedures. The smallest crystals observed with ASEM were a few μm in width, and ASEM can be used with non-transparent solutions. Furthermore, the growth of salt crystals could be monitored in the ASEM, and the difference in contrast between salt and protein crystals made it easy to distinguish between these two types of microcrystals. These results indicate that the ASEM could be an important new tool for the screening of protein microcrystals. PMID:22949879

  10. Direct Observation of the Injection Dynamics of a Laser Wakefield Accelerator Using Few-Femtosecond Shadowgraphy.

    PubMed

    Sävert, A; Mangles, S P D; Schnell, M; Siminos, E; Cole, J M; Leier, M; Reuter, M; Schwab, M B; Möller, M; Poder, K; Jäckel, O; Paulus, G G; Spielmann, C; Skupin, S; Najmudin, Z; Kaluza, M C

    2015-07-31

    We present few-femtosecond shadowgraphic snapshots taken during the nonlinear evolution of the plasma wave in a laser wakefield accelerator with transverse synchronized few-cycle probe pulses. These snapshots can be directly associated with the electron density distribution within the plasma wave and give quantitative information about its size and shape. Our results show that self-injection of electrons into the first plasma-wave period is induced by a lengthening of the first plasma period. Three-dimensional particle-in-cell simulations support our observations. PMID:26274425