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Sample records for core capping leads

  1. Devon island ice cap: core stratigraphy and paleoclimate.

    PubMed

    Koerner, R M

    1977-04-01

    Valuable paleoclimatic information can be gained by studying the distribution of melt layers in deep ice cores. A profile representing the percentage of ice in melt layers in a core drilled from the Devon Island ice cap plotted against both time and depth shows that the ice cap has experienced a period of very warm summers since 1925, following a period of colder summers between about 1600 and 1925. The earlier period was coldest between 1680 and 1730. There is a high correlation between the melt-layer ice percentage and the mass balance of the ice cap. The relation between them suggests that the ice cap mass balance was zero (accumulation equaled ablation) during the colder period but is negative in the present warmer one. There is no firm evidence of a present cooling trend in the summer conditions on the ice cap. A comparison with the melt-layer ice percentage in cores from the other major Canadian Arctic ice caps shows that the variation of summer conditions found for the Devon Island ice cap is representative for all the large ice caps for about 90 percent of the time. There is also a good correlation between melt-layer percentage and summer sea-ice conditions in the archipelago. This suggests that the search for the northwest passage was influenced by changing climate, with the 19th-century peak of the often tragic exploration coinciding with a period of very cold summers.

  2. Modeling the Arm II core in MicroCap IV

    SciTech Connect

    Dalton, A.C.

    1996-11-01

    This paper reports on how an electrical model for the core of the Arm II machine was created and how to use this model. We wanted to get a model for the electrical characteristics of the ARM II core, in order to simulate this machine and to assist in the design of a future machine. We wanted this model to be able to simulate saturation, variable loss, and reset. Using the Hodgdon model and the circuit analysis program MicroCap IV, this was accomplished. This paper is written in such a way as to allow someone not familiar with the project to understand it.

  3. Radiation exposure benefit of a lead cap in invasive cardiology.

    PubMed

    Kuon, E; Birkel, J; Schmitt, M; Dahm, J B

    2003-10-01

    Occupational head exposure to radiation in cardiologists may cause radiation induced cataracts and an increased risk of brain cancer. To determine the effectiveness of 0.5 mm lead equivalent caps, not previously used in invasive cardiology, in comparison with a 1.0 mm lead equivalent ceiling mounted lead glass screen. An anthropomorphic Alderson-Rando phantom was used to represent the patient. Scatter entrance skin air kerma to the operator position (S-ESAK-O) was measured during fluoroscopy for all standard angulations and the S-ESAK-O per dose-area product (DAP) calculated, as applied to the phantom. Measured mean (SD) left/right anterior oblique angulation ratios of S-ESAK-O without lead devices were 23.1 (10.1), and varied as a function of tube angulation, body height, and angle of incidence. S-ESAK-O/DAP decreased with incremental operator body height by 10 (3)% per 10 cm. A 1.0 mm lead glass shield reduced mean S-ESAK-O/DAP originating from coronary angiography from 1089 (764) to 54 (29) nSv/Gy x cm2. A 0.5 mm lead cap was effective in lowering measured levels to 1.8 (1.1) nSv/Gy x cm2. Both devices together enabled attenuation to 0.5 (0.1) nSv/Gy x cm2. The most advantageous line of vision for protection of the operator's eyes was > or = 60 degrees rightward. Use of 0.5 mm lead caps proved highly effective, attenuating S-ESAK-O to 2.7 (2.0) x 10(-3) of baseline, and to 1.2 (1.4) x 10(-3) of baseline where there was an additional 1.0 mm lead glass shield. These results could vary according to the x ray systems used, catheterisation protocols, and correct use of radiation protection devices.

  4. Investigation of fibrous cap stresses on vulnerable plaques leading to heart attacks.

    PubMed

    Hsiao, Hao-Ming; Wu, Yi-Yu; Tsai, Bo-Chian; Chen, Yung-Chi; Cheng, Yu-Han

    2015-09-10

    Rupture-prone plaques in the coronary arteries, called ``vulnerable plaques'', are recognized as the key factor in acute myocardial infarction. Vulnerable plaques have a thin fibrous cap over a large fatty core and are highly susceptible to rupture. In general, this type of plaque rupture is mainly associated with stress concentrated on the fibrous cap. Fibrous cap stresses are counted among the most important factors in the plaque rupture process and must be taken into consideration when assessing the plaque vulnerability leading to heart attacks. The objective of this paper was to investigate the effects of nitinol stent deployment on the morphological changes of vulnerable plaques and then to propose a new stent design concept for effectively reducing fibrous cap stresses and the associated rupture risk. The deployment of a self-expanding nitinol stent was modeled, and the resulting stress distribution on the fibrous cap was investigated. The fibrous cap stresses were more uniformly distributed and the maximum stress was reduced by 13% when the crown number of the stent was increased. This study demonstrates an excellent approach to stent design that could effectively reduce the risk of a vulnerable plaque rupturing and causing a heart attack.

  5. Climatic ice core records from the tropical quelccaya ice cap.

    PubMed

    Thompson, L G; Hastenrath, S; Arnao, B M

    1979-03-23

    The Quelccaya Ice Cap in the easternmost glaciated mountain chain of the Peruvian Andes has been studied in four recentfield seasons. Ice cores to a depth of 15 meters have been retrieved at the summit dome (elevation, 5650 meters) and two other locations and used for microparticle, isotope, and beta radioactivity measurements. A concurrent study of the present climate and the heat and mass budgets is being made to permit a paleoclimatic interpretation of deep core records. The results indicate the need for a revision of the isotope "thermometry" for application in the tropics. However, the seasonality of the beta radioactivity, microparticle content, and isotope ratios offers the prospect of a mass balance chronology. This is important in that precipitation is believed to be a more indicative paleoclimatic parameter than temperature in the tropics.

  6. Cap inflammation leads to higher plaque cap strain and lower cap stress: An MRI-PET/CT-based FSI modeling approach.

    PubMed

    Tang, Dalin; Yang, Chun; Huang, Sarayu; Mani, Venkatesh; Zheng, Jie; Woodard, Pamela K; Robson, Philip; Teng, Zhongzhao; Dweck, Marc; Fayad, Zahi A

    2017-01-04

    Plaque rupture may be triggered by extreme stress/strain conditions. Inflammation is also implicated and can be imaged using novel imaging techniques. The impact of cap inflammation on plaque stress/strain and flow shear stress were investigated. A patient-specific MRI-PET/CT-based modeling approach was used to develop 3D fluid-structure interaction models and investigate the impact of inflammation on plaque stress/strain conditions for better plaque assessment. 18FDG-PET/CT and MRI data were acquired from 4 male patients (average age: 66) to assess plaque characteristics and inflammation. Material stiffness for the fibrous cap was adjusted lower to reflect cap weakening causing by inflammation. Setting stiffness ratio (SR) to be 1.0 (fibrous tissue) for baseline, results for SR=0.5, 0.25, and 0.1 were obtained. Thin cap and hypertension were also considered. Combining results from the 4 patients, mean cap stress from 729 cap nodes was lowered by 25.2% as SR went from 1.0 to 0.1. Mean cap strain value for SR=0.1 was 0.313, 114% higher than that from SR=1.0 model. The thin cap SR=0.1 model had 40% mean cap stress decrease and 81% cap strain increase compared with SR=1.0 model. The hypertension SR=0.1 model had 19.5% cap stress decrease and 98.6% cap strain increase compared with SR=1.0 model. Differences of flow shear stress with 4 different SR values were limited (<10%). Cap inflammation may lead to large cap strain conditions when combined with thin cap and hypertension. Inflammation also led to lower cap stress. This shows the influence of inflammation on stress/strain calculations which are closely related to plaque assessment. Copyright © 2016 Elsevier Ltd. All rights reserved.

  7. Resident CAPS on dense-core vesicles docks and primes vesicles for fusion

    PubMed Central

    Kabachinski, Greg; Kielar-Grevstad, D. Michelle; Zhang, Xingmin; James, Declan J.; Martin, Thomas F. J.

    2016-01-01

    The Ca2+-dependent exocytosis of dense-core vesicles in neuroendocrine cells requires a priming step during which SNARE protein complexes assemble. CAPS (aka CADPS) is one of several factors required for vesicle priming; however, the localization and dynamics of CAPS at sites of exocytosis in live neuroendocrine cells has not been determined. We imaged CAPS before, during, and after single-vesicle fusion events in PC12 cells by TIRF micro­scopy. In addition to being a resident on cytoplasmic dense-core vesicles, CAPS was present in clusters of approximately nine molecules near the plasma membrane that corresponded to docked/tethered vesicles. CAPS accompanied vesicles to the plasma membrane and was present at all vesicle exocytic events. The knockdown of CAPS by shRNA eliminated the VAMP-2–dependent docking and evoked exocytosis of fusion-competent vesicles. A CAPS(ΔC135) protein that does not localize to vesicles failed to rescue vesicle docking and evoked exocytosis in CAPS-depleted cells, showing that CAPS residence on vesicles is essential. Our results indicate that dense-core vesicles carry CAPS to sites of exocytosis, where CAPS promotes vesicle docking and fusion competence, probably by initiating SNARE complex assembly. PMID:26700319

  8. Dansgaard-Oeschger cycles observed in the Greenland ReCAP ice core project

    NASA Astrophysics Data System (ADS)

    Kjær, Helle Astrid; Vallelonga, Paul; Vinther, Bo; Simonsen, Marius; Maffezzoli, Niccoló; Gkinis, Vasileios; Svensson, Anders; Jensen, Camilla Marie; Dallmayr, Remi; Spolaor, Andrea; Edwards, Ross

    2017-04-01

    The new REnland ice CAP (RECAP) ice core was drilled in summer 2015 in Greenland and measured by means of Continuous flow analysis (CFA) during the last 3 months of 2015. The Renland ice core was obtained as part of the ReCAP project, extending 584.11 meters to the bottom of the Renland ice cap located in east Greenland. The unique position on a mountain saddle above 2000 meters altitude, but close to the coast, ensures that the Renland ice core offers high accumulation, but also reaches far back in time. Results show that despite the short length the RECAP ice core holds ice all the way back to the past warm interglacial period, the Eemian. The glacial section is strongly thinned and covers on 20 meters of the ReCAP core, but nonetheless due to the high resolution of the measurements all 25 expected DO events could be identified. The record was analyzed for multiple elements including the water isotopes, forest fire tracers NH4+ and black carbon, insoluble dust particles by means of Abakus laser particle counter and the dust ion Ca2+, sea salt Na+, and sea ice proxies as well as acidity useful for finding volcanic layers to date the core. Below the glacial section another 20 meters of warm Eemian ice have been analysed. Here we present the chemistry results as obtained by continuous flow analysis (CFA) and compare the glacial section with the chemistry profile from other Greenland ice cores.

  9. Earth's polar cap ionization patches lead to ion upflow

    NASA Astrophysics Data System (ADS)

    Zhang, Q. H.; Zong, Q.; Lockwood, M. M.; Liang, J.; Zhang, B.; Moen, J. I.; Zhang, S.; Zhang, Y.; Ruohoniemi, J. M.; Thomas, E. G.; Liu, R.; Dunlop, M. W.; Yang, H. G.; Hu, H.; Liu, Y.; Lester, M.

    2014-12-01

    The Earth constantly losses matter through ions escaping from the polar ionosphere. This makes the ionosphere as an important source of plasma for the magnetosphere and could modulate atmospheric isotope abundances on geological timescales, depending on what fraction of the upflowing ions subsequently return to the ionosphere and what fraction are ejected into interplanetary space. It has been proposed that the magnetosphere is dynamically modulated by the presence of the ionospheric ions, particularly heavy ions O+, during magnetic substorms and storms. The origin and formation mechanism of ionospheric ion upflow is, however, poorly understood, particularly under disturbed space weather conditions. We report simultaneous direct observations of ion upflow and a patch of ionization at the center of the polar cap region during a geomagnetic storm. Our observations indicate enhanced fluxes of upwelling O+ ions originate from the patch and were accelerated by the enhanced ambipolar electric field. This enhancement is caused by soft electron precipitations. Polar cap patches therefore provide an important source of upwelling ions for accelerations mechanisms at greater altitudes which can eject the ions. These observations give new insight into the processes of ionosphere-magnetosphere coupling and the potential loss of terrestrial water dissociation products into space which, although extremely slow in the case of Earth, may be significant for other planets and moons.

  10. ReCAP: ASCO Core Curriculum for Cancer Survivorship Education.

    PubMed

    Shapiro, Charles L; Jacobsen, Paul B; Henderson, Tara; Hurria, Arti; Nekhlyudov, Larissa; Ng, Andrea; Surbone, Antonella; Mayer, Deborah K; Rowland, Julia H; Shapiro, Charles L; Jacobsen, Paul B; Henderson, Tara; Hurria, Arti; Nekhlyudov, Larissa; Ng, Andrea; Surbone, Antonella; Mayer, Deborah K; Rowland, Julia H

    2016-02-01

    The number of cancer survivors is increasing exponentially. Currently there about 15 million cancer survivors, and by 2025, there will be nearly 20 million. Who will provide survivorship care, what are evidenced-based or best care practices, what are best methods to disseminate this information and assess its impact on physician practice, and what are the most cost-effective health care delivery models to serve the majority of survivors? The ASCO Survivorship Committee in collaboration with the ASCO Professional Development Committee developed a core curriculum and core competencies for physicians, allied health professionals, training programs, and policymaking organizations. Adapted from Institute of Medicine recommendations for survivorship care, the core curriculum and competencies include the following subheadings: surveillance for recurrence and second malignancies, long-term and late effects, health promotion and prevention, psychosocial well-being, special populations including adolescent and young adult survivors, older adult cancer survivors, caregivers of cancer survivors and communication and care coordination. An environmental scan (a process that systematically surveys and interprets relevant data to identify opportunities and barriers) for survivorship was performed. Although survivorship content exists in various courses, conferences, guidelines, and Web-based applications, the information is incomplete and not easily found. Hence, there was a need for this content to be easy to access and available in one place. Content experts formulated the individual sections based on the environmental scan and their knowledge of the various subheadings. Both an environmental scan and a comprehensive literature review have standard methodologies. The differences are in scope; an environmental scan is more like an overview, and the standard literature review is more granular. For this article, we felt that environmental scan better served the purpose of

  11. Ablation of cyclase-associated protein 2 (CAP2) leads to cardiomyopathy.

    PubMed

    Peche, Vivek S; Holak, Tad A; Burgute, Bhagyashri D; Kosmas, Kosmas; Kale, Sushant P; Wunderlich, F Thomas; Elhamine, Fatiha; Stehle, Robert; Pfitzer, Gabriele; Nohroudi, Klaus; Addicks, Klaus; Stöckigt, Florian; Schrickel, Jan W; Gallinger, Julia; Schleicher, Michael; Noegel, Angelika A

    2013-02-01

    Cyclase-associated proteins are highly conserved proteins that have a role in the regulation of actin dynamics. Higher eukaryotes have two isoforms, CAP1 and CAP2. To study the in vivo function of CAP2, we generated mice in which the CAP2 gene was inactivated by a gene-trap approach. Mutant mice showed a decrease in body weight and had a decreased survival rate. Further, they developed a severe cardiac defect marked by dilated cardiomyopathy (DCM) associated with drastic reduction in basal heart rate and prolongations in atrial and ventricular conduction times. Moreover, CAP2-deficient myofibrils exhibited reduced cooperativity of calcium-regulated force development. At the microscopic level, we observed disarrayed sarcomeres with development of fibrosis. We analyzed CAP2's role in actin assembly and found that it sequesters G-actin and efficiently fragments filaments. This activity resides completely in its WASP homology domain. Thus CAP2 is an essential component of the myocardial sarcomere and is essential for physiological functioning of the cardiac system, and a deficiency leads to DCM and various cardiac defects.

  12. Rotavirus open cores catalyze 5'-capping and methylation of exogenous RNA: evidence that VP3 is a methyltransferase.

    PubMed

    Chen, D; Luongo, C L; Nibert, M L; Patton, J T

    1999-12-05

    Rotavirus open cores prepared from purified virions consist of three proteins: the RNA-dependent RNA polymerase, VP1; the core shell protein, VP2; and the guanylyltransferase, VP3. In addition to RNA polymerase activity, open cores have been shown to contain a nonspecific guanylyltransferase activity that caps viral and nonviral RNAs in vitro. In this study, we examined the structure of RNA caps made by open cores and have analyzed open cores for other capping-related enzymatic activities. Utilizing RNase digestion and thin-layer chromatography, we found that the majority ( approximately 70%) of caps made by open cores contain the tetraphosphate linkage, GppppG, rather than the triphosphate linkage, GpppG, found on mRNAs made by rotavirus double-layered particles. Enzymatic analysis indicated that the GppppG caps resulted from the lack of a functional RNA 5'-triphosphatase in open cores, to remove the gamma-phosphate from the RNA prior to capping. RNA 5'-triphosphatases commonly exhibit an associated nucleoside triphosphatase activity, and this too was not detected in open cores. Caps of some RNAs contained an extra GMP moiety (underlined) and had the structure 3'-GpGp(p)ppGpGpC-RNA-3'. The origin of the extra GMP is not known but may reflect the cap serving as a primer for RNA synthesis. Methylated caps were produced in the presence of the substrate, S-adenosyl-l-methionine (SAM), indicating that open cores contain methyltransferase activity. UV cross-linking showed that VP3 specifically binds SAM. Combined with the results of earlier studies, our results suggest that the viral guanylyltransferase and methyltransferase are both components of VP3 and, therefore, that VP3 is a multifunctional capping enzyme.

  13. CAPS-1 promotes fusion competence of stationary dense-core vesicles in presynaptic terminals of mammalian neurons

    PubMed Central

    Farina, Margherita; van de Bospoort, Rhea; He, Enqi; Persoon, Claudia M; van Weering, Jan RT; Broeke, Jurjen H; Verhage, Matthijs; Toonen, Ruud F

    2015-01-01

    Neuropeptides released from dense-core vesicles (DCVs) modulate neuronal activity, but the molecules driving DCV secretion in mammalian neurons are largely unknown. We studied the role of calcium-activator protein for secretion (CAPS) proteins in neuronal DCV secretion at single vesicle resolution. Endogenous CAPS-1 co-localized with synaptic markers but was not enriched at every synapse. Deletion of CAPS-1 and CAPS-2 did not affect DCV biogenesis, loading, transport or docking, but DCV secretion was reduced by 70% in CAPS-1/CAPS-2 double null mutant (DKO) neurons and remaining fusion events required prolonged stimulation. CAPS deletion specifically reduced secretion of stationary DCVs. CAPS-1-EYFP expression in DKO neurons restored DCV secretion, but CAPS-1-EYFP and DCVs rarely traveled together. Synaptic localization of CAPS-1-EYFP in DKO neurons was calcium dependent and DCV fusion probability correlated with synaptic CAPS-1-EYFP expression. These data indicate that CAPS-1 promotes fusion competence of immobile (tethered) DCVs in presynaptic terminals and that CAPS-1 localization to DCVs is probably not essential for this role. DOI: http://dx.doi.org/10.7554/eLife.05438.001 PMID:25719439

  14. CAPS-1 promotes fusion competence of stationary dense-core vesicles in presynaptic terminals of mammalian neurons.

    PubMed

    Farina, Margherita; van de Bospoort, Rhea; He, Enqi; Persoon, Claudia M; van Weering, Jan R T; Broeke, Jurjen H; Verhage, Matthijs; Toonen, Ruud F

    2015-02-26

    Neuropeptides released from dense-core vesicles (DCVs) modulate neuronal activity, but the molecules driving DCV secretion in mammalian neurons are largely unknown. We studied the role of calcium-activator protein for secretion (CAPS) proteins in neuronal DCV secretion at single vesicle resolution. Endogenous CAPS-1 co-localized with synaptic markers but was not enriched at every synapse. Deletion of CAPS-1 and CAPS-2 did not affect DCV biogenesis, loading, transport or docking, but DCV secretion was reduced by 70% in CAPS-1/CAPS-2 double null mutant (DKO) neurons and remaining fusion events required prolonged stimulation. CAPS deletion specifically reduced secretion of stationary DCVs. CAPS-1-EYFP expression in DKO neurons restored DCV secretion, but CAPS-1-EYFP and DCVs rarely traveled together. Synaptic localization of CAPS-1-EYFP in DKO neurons was calcium dependent and DCV fusion probability correlated with synaptic CAPS-1-EYFP expression. These data indicate that CAPS-1 promotes fusion competence of immobile (tethered) DCVs in presynaptic terminals and that CAPS-1 localization to DCVs is probably not essential for this role.

  15. Tennis core strings of polyamide-6 modified by surface-capped nano-silica

    NASA Astrophysics Data System (ADS)

    Liu, Juan; Yi, Hongling; Lin, Heng; Zheng, Baicun

    2013-01-01

    A new method that modified silica nanoparticles were infused into PA6 is to produce tennis core string through a melt-extrusion process. The idea was to produce a highly strong and elastic tennis core string of PA6, utilizing the interactions between modified silica and polymer. The effects of surface-capped nano-silica on the strength and elongation of tennis core string were studied. It has been observed that with the infusion of silica nanoparticles modified by γ-glycidoxypropyltrimethoxysilane (GPS), the stress at breaking and E-modulus of tennis core string is enhanced by 46.24% and 15.17% comparing with neat PA6 with changeless elongation at breaking at a critical concentration. The source of this improvement has been traced to the produced strong covalent bond and hydrogen bond between epoxy groups and-COOH and-NH2 in polyamide. Besides, compared with kinds of others strings of previous research results, tennis core string added nano-silica modified by γ-glycidoxypropyltrimethoxysilane (GPS) has a strength at breaking at 352.43 MPa exceeding the natural gut string, the polyvinylidene fluoride (PVDF), Monofil string and integrated nylon string by 42.05%, 4.49% and 9.38%, respectively. Meanwhile, tennis core string of polyamide modified by surface-capped nanosilica (PGMNS) has a higher elastic ratio at 0.15 than the other four strings.

  16. A 1500-year record of tropical precipitation in ice cores from the quelccaya ice cap, peru.

    PubMed

    Thompson, L G; Mosley-Thompson, E; Bolzan, J F; Koci, B R

    1985-09-06

    Two ice cores, covering 1500 years of climatic information, from the summit (5670 meters) of the tropical Quelccaya ice cap, in the Andes of southern Peru, provide information on general environmental conditions including droughts, volcanic activity, moisture sources, temperature, and glacier net balance. The net balance record reconstructed from these cores reflects major precipitation trends for the southern Andes of Peru. These records indicate extended dry periods between 1720 and 1860, 1250 and 1310, and 570 and 610; wet conditions prevailed between 1500 and 1720. Establishing a tropical precipitation record may help explain climatic fluctuations since the tropical evaporation-precipitation cycle is a principal mechanism driving the atmospheric circulation.

  17. Leading Change: Transitioning to the Common Core

    ERIC Educational Resources Information Center

    Brandt, Brian

    2012-01-01

    For many school districts in the United States, making the transition to the Common Core State Standards (CCSS) is proving to be a challenge at a time when they are already facing many obstacles, not the least of which is dwindling financial resources. A change of this magnitude cannot be made haphazardly; to be successful in its goal of helping…

  18. Lead, zinc, and strontium in limestone cap rock from Tatum salt dome, Mississippi

    SciTech Connect

    Saunders, J.A.

    1988-09-01

    Limestone cap rock at Tatum salt dome, Mississippi, contains disseminated pyrite, sphalerite, and galena, and disseminated to massive amounts of strontianite (SrCO/sub 3/) and celestite (SrSO/sub 4/). Sulfide minerals are locally present in bitumen-rich areas of the upper, massive portion of the limestone cap rock, whereas strontium minerals are disseminated throughout this zone. However, sulfide and strontium minerals are most abundant in the lower banded portion of the limestone cap rock, which consists of alternating subhorizontal light and dark-colored bands. The dark bands are composed of calcite of variable grain size, sulfides, quartz, dolomite, albite, and up to 1% bitumen that apparently formed by the biodegradation of crude oil. Lighter bands are composed of variable amounts of coarsely crystalline, euhedral calcite, strontianite, and celestite resulting in strontium (Sr) contents of up to 30% locally. Banded limestone cap rock at Tatum dome formed at the top of the actively dissolving anhydrite zone by a combination of sulfate reduction and oxidation of liquid hydrocarbons by bacteria to cause the precipitation of calcite and sulfide minerals and the accumulation of insoluble residue from the anhydrite (quartz, albite, dolomite). Lead and zinc in the sulfide minerals could have been derived from the dissolving anhydrite, but the abundance of Sr minerals present requires an external source. Present-day oil field brines in central Mississippi contain up to 3000 ppm Sr, and basin brines of similar composition apparently contributed Sr to the cap-rock environment during formation.

  19. Dissolved Chemical Ions in an Ice Core of Grigoriev Ice Cap, Kyrgyz Tien Shan

    NASA Astrophysics Data System (ADS)

    SHUN, A.; Takeuchi, N.; Sera, S.; Fujita, K.; Okamoto, S.; Naoki, K.; Aizen, V. B.

    2012-12-01

    Snow and ice of glaciers contain various chemical ions supplied through the atmosphere and preserve them for a long period of time. Thus, analysis of soluble ions in glaciers is important to reveal material circulation and climate change in the cryosphere. Many glaciers are distributed over the mountains of the Central Asia. Chemical analysis of ice cores recovered from there play an important role to understand the atmosphere and material circulation peculiar to the Eurasian Continent. In this study, we analyzed the concentration of major ions in the ice core drilled on Grigoriev Ice Cap, Kyrgys Tien Shan, located in the northwestern part of Central Asia. We aim to understand material circulation in this area based on the chemical records. Then, we have attempted to reconstruct the environmental change of Central Asia, combining the chronology, hydrogen and oxygen stable isotope ratio, and density of dust in the ice core analyzed by prior researches. In this study, we used 2,176 samples of a snow pit and ice core from the surface to bed (86.87 m total length) on the top of Grigoriev Ice Cap (4,660 m high), Kyrgys Tien Shan in September, 2007. Samples were cut every 1-5 cm and scraped thinly, and transported frozen to Chiba University, Japan. After that, we dispensed those for various experiments, and analyzed the concentration of major ions using ion chromatography. By the way, it is estimated that the date of the bottom of this ice core is approximately 12,000 years ago by prior researches. The concentration of major ions dissolved in the ice core of Grigoriev Ice Cap revealed that Ca is the most dominant species in the measured ions and it accounted for more than 50 % (Eq ratio) of the mean of the entire core. This suggests that CaCO3 included in mineral dust derived from deserts around Tien Shan strongly influence the chemical composition of the Ice Cap. In addition, this composition is similar to those of Urumqi No.1 Glacier (Tien Shan), Mustagh Ata Glacier

  20. Mitochondrial Respiration Is Reduced in Atherosclerosis, Promoting Necrotic Core Formation and Reducing Relative Fibrous Cap Thickness.

    PubMed

    Yu, Emma P K; Reinhold, Johannes; Yu, Haixiang; Starks, Lakshi; Uryga, Anna K; Foote, Kirsty; Finigan, Alison; Figg, Nichola; Pung, Yuh-Fen; Logan, Angela; Murphy, Michael P; Bennett, Martin

    2017-09-28

    Mitochondrial DNA (mtDNA) damage is present in murine and human atherosclerotic plaques. However, whether endogenous levels of mtDNA damage are sufficient to cause mitochondrial dysfunction and whether decreasing mtDNA damage and improving mitochondrial respiration affects plaque burden or composition are unclear. We examined mitochondrial respiration in human atherosclerotic plaques and whether augmenting mitochondrial respiration affects atherogenesis. Human atherosclerotic plaques showed marked mitochondrial dysfunction, manifested as reduced mtDNA copy number and oxygen consumption rate in fibrous cap and core regions. Vascular smooth muscle cells derived from plaques showed impaired mitochondrial respiration, reduced complex I expression, and increased mitophagy, which was induced by oxidized low-density lipoprotein. Apolipoprotein E-deficient (ApoE(-/-)) mice showed decreased mtDNA integrity and mitochondrial respiration, associated with increased mitochondrial reactive oxygen species. To determine whether alleviating mtDNA damage and increasing mitochondrial respiration affects atherogenesis, we studied ApoE(-/-) mice overexpressing the mitochondrial helicase Twinkle (Tw(+)/ApoE(-/-)). Tw(+)/ApoE(-/-) mice showed increased mtDNA integrity, copy number, respiratory complex abundance, and respiration. Tw(+)/ApoE(-/-) mice had decreased necrotic core and increased fibrous cap areas, and Tw(+)/ApoE(-/-) bone marrow transplantation also reduced core areas. Twinkle increased vascular smooth muscle cell mtDNA integrity and respiration. Twinkle also promoted vascular smooth muscle cell proliferation and protected both vascular smooth muscle cells and macrophages from oxidative stress-induced apoptosis. Endogenous mtDNA damage in mouse and human atherosclerosis is associated with significantly reduced mitochondrial respiration. Reducing mtDNA damage and increasing mitochondrial respiration decrease necrotic core and increase fibrous cap areas independently of changes

  1. Outcomes Associated with Extraction versus Capping and Abandoning Pacing and Defibrillator Leads.

    PubMed

    Pokorney, Sean D; Mi, Xiaojuan; Lewis, Robert K; Greiner, Melissa; Epstein, Laurence M; Carrillo, Roger G; Zeitler, Emily P; Al-Khatib, Sana M; Hegland, Donald D; Piccini, Jonathan P

    2017-08-22

    Background -Lead management is an increasingly important aspect of care in patients with cardiac implantable electronic devices (CIED); however, relatively little is known about long-term outcomes after capping and abandoning leads. Methods -Using the 5% Medicare sample, we identified patients with (1) de novo CIED implants between 1/1/2000 and 12/31/2013 and (2) a subsequent lead addition or extraction ≥12 months after the de novo implant. Patients who underwent extraction for infection were excluded. Using multivariable Cox proportional hazards models, cumulative incidence of all-cause mortality, device-related infection, device revision, and lead extraction at 1 and 5 years were compared for the extract versus the cap and abandon groups. Results -Among 6,859 patients, 1,113 (16.2%) underwent extraction, while 5,746 (83.8%) underwent capping and abandonment. Extraction patients tended to be younger (median 78 vs 79 years, p<0.0001), were less likely to be male (65% vs 68%, p=0.05), and had shorter lead dwell time (median 3.0 vs 4.0 years, p<0.0001) and fewer comorbidities. Over a median follow-up of 2.4 years (25(th), 75(th) percentiles: 1.0, 4.3 years) the overall 1-year and 5-year cumulative incidence of mortality was 13.5% (95% CI 12.7%-14.4%) and 54.3% (95% CI 52.8%-55.8%), respectively. Extraction was associated with a lower risk of device infection at 5 years relative to capping (adjusted HR 0.78, 95% CI 0.62-0.97, p=0.027). There was no association between extraction and mortality, lead revision, or lead extraction at 5 years. Conclusions -Elective lead extraction for non-infectious indications had similar long-term survival to capping and abandoning leads in a Medicare population. However, extraction was associated with lower risk of device infections at 5 years.

  2. Studies on the chemical synthesis and characterization of lead oxide nanoparticles with different organic capping agents

    SciTech Connect

    Arulmozhi, K. T.; Mythili, N.

    2013-12-15

    Lead oxide (PbO) nanoparticles were chemically synthesized using Lead (II) acetate as precursor. The effects of organic capping agents such as Oleic acid, Ethylene Diamine Tetra Acetic acid (EDTA) and Cetryl Tri Methyl Butoxide (CTAB) on the size and morphology of the nanoparticles were studied. Characterization techniques such as X-ray diffraction (XRD), Fourier Transform-Infrared spectroscopy (FT-IR), Photoluminescence (PL) Field Emission Scanning Electron Microscopy (FE-SEM), Energy Dispersive Spectroscopy (EDS) and Transmission Electron Microscopy (TEM) were used to analyse the prepared nanoparticles for their physical, structural and optical properties. The characterization studies reveal that the synthesized PbO nanoparticles had well defined crystalline structure and sizes in the range of 25 nm to 36 nm for capping agents used and 40 nm for pure PbO nanoparticles.

  3. Timescale Calculations for Ice Core Drilling Sites on the Temperate Ice Caps in Iceland

    NASA Astrophysics Data System (ADS)

    Thorsteinsson, T.; Einarsson, B.

    2005-12-01

    Modelling of age vs. depth profiles and annual-layer thickness changes with depth in ice sheets forms part of the investigations carried out prior to the selection of ice core drilling sites. The well known Nye model, which assumes a constant vertical strain rate with depth in an ice sheet of thickness H is generally applicable in the upper half of polar and temperate ice caps, but the assumption of a constant vertical strain rate is unrealistic near the bed in an ice sheet frozen to bedrock. Dansgaard-Johnsen (D-J) type models assume that the vertical strain rate is constant down to height h above bedrock and then decreases linearly with depth towards zero at the bed. The parameter h can be calibrated according to the way in which the horizontal velocity varies with depth. Here we introduce a new derivation of the D-J model that accounts for bottom melting due to the geothermal heat flux, which averages 200 mW/m2 in Iceland. The model is then applied to five different locations on the temperate ice caps in Iceland, with ice thicknesses varying between 220 m and 850 m and accumulation rates ranging between 2.0 and 3.6 m ice/year. Data from ice cores drilled at three of these sites are used to calibrate the model. For the summit location on the Hofsjokull ice cap (H = 300 m), we find that a D-J model with a relatively high h/H ratio reproduces the timescale from a 100 m ice core better than the Nye model. Results indicate that a continuous precipitation record covering the last 400-500 years could be retrieved at the Hofsjokull summit (1790 m a.s.l.), and the assumption of bottom melting has a large effect on the modelled timescale at this site, yielding 50% lower ages at 90% of the ice depth than model runs that neglect bottom melting. For deeper drillings in Iceland, the ice-filled caldera at Bardarbunga, NW-Vatnajokull (H = 850 m), where a 415 m core was drilled in 1972, is among the most promising sites. Selection of the h/H ratio in the D-J model for timescale

  4. The Earth's missing lead may not be in the core.

    PubMed

    Lagos, M; Ballhaus, C; Münker, C; Wohlgemuth-Ueberwasser, C; Berndt, J; Kuzmin, Dmitry V

    2008-11-06

    Relative to the CI chondrite class of meteorites (widely thought to be the 'building blocks' of the terrestrial planets), the Earth is depleted in volatile elements. For most elements this depletion is thought to be a solar nebular signature, as chondrites show depletions qualitatively similar to that of the Earth. On the other hand, as lead is a volatile element, some Pb may also have been lost after accretion. The unique (206)Pb/(204)Pb and (207)Pb/(204)Pb ratios of the Earth's mantle suggest that some lead was lost about 50 to 130 Myr after Solar System formation. This has commonly been explained by lead lost via the segregation of a sulphide melt to the Earth's core, which assumes that lead has an affinity towards sulphide. Some models, however, have reconciled the Earth's lead deficit with volatilization. Whichever model is preferred, the broad coincidence of U-Pb model ages with the age of the Moon suggests that lead loss may be related to the Moon-forming impact. Here we report partitioning experiments in metal-sulphide-silicate systems. We show that lead is neither siderophile nor chalcophile enough to explain the high U/Pb ratio of the Earth's mantle as being a result of lead pumping to the core. The Earth may have accreted from initially volatile-depleted material, some lead may have been lost to degassing following the Moon-forming giant impact, or a hidden reservoir exists in the deep mantle with lead isotope compositions complementary to upper-mantle values; it is unlikely though that the missing lead resides in the core.

  5. Lead Halide Perovskites and Other Metal Halide Complexes As Inorganic Capping Ligands for Colloidal Nanocrystals

    PubMed Central

    2014-01-01

    Lead halide perovskites (CH3NH3PbX3, where X = I, Br) and other metal halide complexes (MXn, where M = Pb, Cd, In, Zn, Fe, Bi, Sb) have been studied as inorganic capping ligands for colloidal nanocrystals. We present the methodology for the surface functionalization via ligand-exchange reactions and the effect on the optical properties of IV–VI, II–VI, and III–V semiconductor nanocrystals. In particular, we show that the Lewis acid–base properties of the solvents, in addition to the solvent dielectric constant, must be properly adjusted for successful ligand exchange and colloidal stability. High luminescence quantum efficiencies of 20–30% for near-infrared emitting CH3NH3PbI3-functionalized PbS nanocrystals and 50–65% for red-emitting CH3NH3CdBr3- and (NH4)2ZnCl4-capped CdSe/CdS nanocrystals point to highly efficient electronic passivation of the nanocrystal surface. PMID:24746226

  6. Colloidal 3-mercaptopropionic acid Capped Lead Sulfide Quantum Dots in a Low Boiling Point Solvent.

    PubMed

    Reinhart, Chase C; Johansson, Erik

    2017-04-10

    Colloidal 3-mercaptopropionic acid (3-MPA) capped lead sulfide quantum dots were prepared in a variety of organic solvents stabilized with a quaternary ammonium halide salt. The stabilized colloids' optical properties were studied through optical absorption and emission spectroscopy and found to be dependent on both the concentration of new ligand and stabilizer, and sample age. Nanocrystal ligand chemistry was studied through a combination of (1)H-NMR and 2-dimensional Nuclear Overhauser Effect Spectroscopy (NOESY) which revealed full displacement of the original oleate ligand to form a dynamically exchanging ligand shell. The colloids were studied optically and via NMR as they aged and revealed a quantitative conversion of monomeric 3-mercaptopropionic acid to its dimer, dithiodipropionic acid (dTdPA).

  7. Fluorescence signals of core-shell quantum dots enhanced by single crystalline gold caps on silicon nanowires

    NASA Astrophysics Data System (ADS)

    Christiansen, S. H.; Chou, J. W.; Becker, M.; Sivakov, V.; Ehrhold, K.; Berger, A.; Chou, W. C.; Chuu, D. S.; Gösele, U.

    2009-04-01

    We use nanoscale (20-300 nm in diameter) single crystalline gold (Au)-caps on silicon nanowires (NWs) grown by the vapor-liquid-solid (VLS) growth mechanism to enhance the fluorescence photoluminescence (PL) signals of highly dilute core/shell CdSeTe/ZnS quantum dots (QDs) in aqueous solution (10-5 M). For NWs without Au-caps, as they appear, for example, after Au etching in aqua regia or buffered KI/I2-solution, essentially no fluorescence signal of the same diluted QDs could be observed. Fluorescence PL signals were measured using excitation with a laser wavelength of 633 nm. The signal enhancement by single crystalline, nanoscale Au-caps is discussed and interpreted based on finite element modeling (FEM).

  8. VENUS-F: A fast lead critical core for benchmarking

    SciTech Connect

    Kochetkov, A.; Wagemans, J.; Vittiglio, G.

    2011-07-01

    The zero-power thermal neutron water-moderated facility VENUS at SCK-CEN has been extensively used for benchmarking in the past. In accordance with GEN-IV design tasks (fast reactor systems and accelerator driven systems), the VENUS facility was modified in 2007-2010 into the fast neutron facility VENUS-F with solid core components. This paper introduces the projects GUINEVERE and FREYA, which are being conducted at the VENUS-F facility, and it presents the measurement results obtained at the first critical core. Throughout the projects other fast lead benchmarks also will be investigated. The measurement results of the different configurations can all be used as fast neutron benchmarks. (authors)

  9. Core demonstration lead experiments for irradiation in FFTF

    SciTech Connect

    Dittmer, J.O.; Jackson, R.J.

    1987-01-01

    A major new initiative to develop and irradiate a long-life mixed oxide fuel system in the Fast Flux Test Facility (FFTF) has been implemented by the Westinghouse Hanford Company at the Hanford Engineering Development Lab. for the US Dept. of Energy. The purpose of this new fuel system, called the Core Demonstration Experiment (CDE), is to demonstrate the capability of achieving a 3-yr life in a prototypical heterogeneous reactor environment under prototypical power and temperature conditions. Three Core Demonstration Lead Experiments (CDLEs) will establish the performance characteristics of entire fuel assemblies of wire-wrapped, large diameter, advanced oxide fuel pins with HT-9 stainless steel alloy cladding and wire wrap and an HT-9 duct. Their performance characteristics provided the basis for design, fabrication, and irradiation of the CDE.

  10. An ac susceptibility study in capped Ni/Ni(OH)2 core-shell nanoassemblies: dual peak observations

    NASA Astrophysics Data System (ADS)

    Godsell, Jeffrey F.; Bala, Tanushree; Ryan, Kevin M.; Roy, Saibal

    2011-08-01

    In this study, the ac susceptibility (χ' and χ'') variation with temperature (10-100 K) for oleic acid (OA) capped Ni/Ni(OH)2 core-shell nanoparticle assemblies are reported at frequencies varying from 0.1 to 1000 Hz. Nanoparticle assemblies, with two average particle diameters of ~34 nm and ~14 nm, were synthesized using a wet chemical synthesis approach. Two peaks in the ac susceptibility versus temperature curves are clearly discernable for each of the samples. The first, occurring at ~22 K was attributed to the paramagnetic/antiferromagnetic transition of the Ni(OH)2 present in the shell. The second higher temperature peak was attributed to the superparamagnetic blocking of the pure Ni situated at the core of the nanoparticles. The higher temperature peaks in both the χ' and χ'' curves were observed to increase with increasing frequency. Thus the Néel and the blocking temperatures for such core-shell nanoassemblies were clearly identified from the ac analysis, whereas they were not discernible (superimposed) even from very low dc (FC/ZFC) field measurements. Interparticle interactions within the assemblies were studied through the fitting of phenomenological laws to the experimental datasets. It is observed that even with an OA capping layer, larger Ni/Ni(OH)2 nanoparticles experience a greater degree of sub-capping layer oxidation thus producing lower magnetic interaction strengths.

  11. Single-crystal metal--organic microtubes self-assembled from designed D3 symmetrical nanoclusters with a capped triple-helix pentanuclear M5O6 core.

    PubMed

    Feng, Sisi; Zhu, Miaoli; Lu, Liping; Guo, Maolin

    2007-12-07

    Single-crystal metal-organic microtubular architectures have been fabricated from designed D(3) symmetrical nano clusters with a capped triple-helix pentanuclear M(5)O(6) core under hydrothermal conditions.

  12. Disruption of a conserved CAP-D3 threonine alters condensin loading on mitotic chromosomes leading to chromosome hypercondensation.

    PubMed

    Bakhrebah, Muhammed; Zhang, Tao; Mann, Jeff R; Kalitsis, Paul; Hudson, Damien F

    2015-03-06

    The condensin complex plays a key role in organizing mitotic chromosomes. In vertebrates, there are two condensin complexes that have independent and cooperative roles in folding mitotic chromosomes. In this study, we dissect the role of a putative Cdk1 site on the condensin II subunit CAP-D3 in chicken DT40 cells. This conserved site has been shown to activate condensin II during prophase in human cells, and facilitate further phosphorylation by polo-like kinase I. We examined the functional significance of this phosphorylation mark by mutating the orthologous site of CAP-D3 (CAP-D3(T1403A)) in chicken DT40 cells. We show that this mutation is a gain of function mutant in chicken cells; it disrupts prophase, results in a dramatic shortening of the mitotic chromosome axis, and leads to abnormal INCENP localization. Our results imply phosphorylation of CAP-D3 acts to limit condensin II binding onto mitotic chromosomes. We present the first in vivo example that alters the ratio of condensin I:II on mitotic chromosomes. Our results demonstrate this ratio is a critical determinant in shaping mitotic chromosomes. © 2015 by The American Society for Biochemistry and Molecular Biology, Inc.

  13. Disruption of a Conserved CAP-D3 Threonine Alters Condensin Loading on Mitotic Chromosomes Leading to Chromosome Hypercondensation*

    PubMed Central

    Bakhrebah, Muhammed; Zhang, Tao; Mann, Jeff R.; Kalitsis, Paul; Hudson, Damien F.

    2015-01-01

    The condensin complex plays a key role in organizing mitotic chromosomes. In vertebrates, there are two condensin complexes that have independent and cooperative roles in folding mitotic chromosomes. In this study, we dissect the role of a putative Cdk1 site on the condensin II subunit CAP-D3 in chicken DT40 cells. This conserved site has been shown to activate condensin II during prophase in human cells, and facilitate further phosphorylation by polo-like kinase I. We examined the functional significance of this phosphorylation mark by mutating the orthologous site of CAP-D3 (CAP-D3T1403A) in chicken DT40 cells. We show that this mutation is a gain of function mutant in chicken cells; it disrupts prophase, results in a dramatic shortening of the mitotic chromosome axis, and leads to abnormal INCENP localization. Our results imply phosphorylation of CAP-D3 acts to limit condensin II binding onto mitotic chromosomes. We present the first in vivo example that alters the ratio of condensin I:II on mitotic chromosomes. Our results demonstrate this ratio is a critical determinant in shaping mitotic chromosomes. PMID:25605712

  14. Towards multi-decadal to multi-millennial ice core records from coastal west Greenland ice caps

    NASA Astrophysics Data System (ADS)

    Das, Sarah B.; Osman, Matthew B.; Trusel, Luke D.; McConnell, Joseph R.; Smith, Ben E.; Evans, Matthew J.; Frey, Karen E.; Arienzo, Monica; Chellman, Nathan

    2017-04-01

    The Arctic region, and Greenland in particular, is undergoing dramatic change as characterized by atmospheric warming, decreasing sea ice, shifting ocean circulation patterns, and rapid ice sheet mass loss, but longer records are needed to put these changes into context. Ice core records from the Greenland ice sheet have yielded invaluable insight into past climate change both regionally and globally, and provided important constraints on past surface mass balance more directly, but these ice cores are most often from the interior ice sheet accumulation zone, at high altitude and hundreds of kilometers from the coast. Coastal ice caps, situated around the margins of Greenland, have the potential to provide novel high-resolution records of local and regional maritime climate and sea surface conditions, as well as contemporaneous glaciological changes (such as accumulation and surface melt history). But obtaining these records is extremely challenging. Most of these ice caps are unexplored, and thus their thickness, age, stratigraphy, and utility as sites of new and unique paleoclimate records is largely unknown. Access is severely limited due to their high altitude, steep relief, small surface area, and inclement weather. Furthermore, their relatively low elevation and marine moderated climate can contribute to significant surface melting and degradation of the ice stratigraphy. We recently targeted areas near the Disko Bay region of central west Greenland where maritime ice caps are prevalent but unsampled, as potential sites for new multi-decadal to multi-millennial ice core records. In 2014 & 2015 we identified two promising ice caps, one on Disko Island (1250 m. asl) and one on Nuussuaq Peninsula (1980 m. asl) based on airborne and ground-based geophysical observations and physical and glaciochemical stratigraphy from shallow firn cores. In spring 2015 we collected ice cores at both sites using the Badger-Eclipse electromechanical drill, transported by a medley

  15. Ability of combined Near-Infrared Spectroscopy-Intravascular Ultrasound (NIRS-IVUS) imaging to detect lipid core plaques and estimate cap thickness in human autopsy coronary arteries

    NASA Astrophysics Data System (ADS)

    Grainger, S. J.; Su, J. L.; Greiner, C. A.; Saybolt, M. D.; Wilensky, R. L.; Raichlen, J. S.; Madden, S. P.; Muller, J. E.

    2016-03-01

    The ability to determine plaque cap thickness during catheterization is thought to be of clinical importance for plaque vulnerability assessment. While methods to compositionally assess cap integrity are in development, a method utilizing currently available tools to measure cap thickness is highly desirable. NIRS-IVUS is a commercially available dual imaging method in current clinical use that may provide cap thickness information to the skilled reader; however, this is as yet unproven. Ten autopsy hearts (n=15 arterial segments) were scanned with the multimodality NIRS-IVUS catheter (TVC Imaging System, Infraredx, Inc.) to identify lipid core plaques (LCPs). Skilled readers made predictions of cap thickness over regions of chemogram LCP, using NIRS-IVUS. Artery segments were perfusion fixed and cut into 2 mm serial blocks. Thin sections stained with Movat's pentachrome were analyzed for cap thickness at LCP regions. Block level predictions were compared to histology, as classified by a blinded pathologist. Within 15 arterial segments, 117 chemogram blocks were found by NIRS to contain LCP. Utilizing NIRSIVUS, chemogram blocks were divided into 4 categories: thin capped fibroatheromas (TCFA), thick capped fibroatheromas (ThCFA), pathological intimal thickening (PIT)/lipid pool (no defined cap), and calcified/unable to determine cap thickness. Sensitivities/specificities for thin cap fibroatheromas, thick cap fibroatheromas, and PIT/lipid pools were 0.54/0.99, 0.68/0.88, and 0.80/0.97, respectively. The overall accuracy rate was 70.1% (including 22 blocks unable to predict, p = 0.075). In the absence of calcium, NIRS-IVUS imaging provided predictions of cap thickness over LCP with moderate accuracy. The ability of this multimodality imaging method to identify vulnerable coronary plaques requires further assessment in both larger autopsy studies, and clinical studies in patients undergoing NIRS-IVUS imaging.

  16. Constraining recent lead pollution sources in the North Pacific using ice core stable lead isotopes

    NASA Astrophysics Data System (ADS)

    Gross, B. H.; Kreutz, K. J.; Osterberg, E. C.; McConnell, J. R.; Handley, M.; Wake, C. P.; Yalcin, K.

    2012-08-01

    Trends and sources of lead (Pb) aerosol pollution in the North Pacific rim of North America from 1850 to 2001 are investigated using a high-resolution (subannual to annual) ice core record recovered from Eclipse Icefield (3017 masl; St. Elias Mountains, Canada). Beginning in the early 1940s, increasing Pb concentration at Eclipse Icefield occurs coevally with anthropogenic Pb deposition in central Greenland, suggesting that North American Pb pollution may have been in part or wholly responsible in both regions. Isotopic ratios (208Pb/207Pb and 206Pb/207Pb) from 1970 to 2001 confirm that a portion of the Pb deposited at Eclipse Icefield is anthropogenic, and that it represents a variable mixture of East Asian (Chinese and Japanese) emissions transported eastward across the Pacific Ocean and a North American component resulting from transient meridional atmospheric flow. Based on comparison with source material Pb isotope ratios, Chinese and North American coal combustion have likely been the primary sources of Eclipse Icefield Pb over the 1970-2001 time period. The Eclipse Icefield Pb isotope composition also implies that the North Pacific mid-troposphere is not directly impacted by transpolar atmospheric flow from Europe. Annually averaged Pb concentrations in the Eclipse Icefield ice core record show no long-term trend during 1970-2001; however, increasing208Pb/207Pb and decreasing 206Pb/207Pb ratios reflect the progressive East Asian industrialization and increase in Asian pollutant outflow. The post-1970 decrease in North American Pb emissions is likely necessary to explain the Eclipse Icefield Pb concentration time series. When compared with low (lichen) and high (Mt. Logan ice core) elevation Pb data, the Eclipse ice core record suggests a gradual increase in pollutant deposition and stronger trans-Pacific Asian contribution with rising elevation in the mountains of the North Pacific rim.

  17. Penny ice cap cores, baffin island, canada, and the wisconsinan foxe dome connection: two states of hudson bay ice cover

    PubMed

    Fisher; Koerner; Bourgeois; Zielinski; Wake; Hammer; Clausen; Gundestrup; Johnsen; Goto-Azuma; Hondoh; Blake; Gerasimoff

    1998-01-30

    Ice cores from Penny Ice Cap, Baffin Island, Canada, provide continuous Holocene records of oxygen isotopic composition (delta18O, proxy for temperature) and atmospheric impurities. A time scale was established with the use of altered seasonal variations, some volcanic horizons, and the age for the end of the Wisconsin ice age determined from the GRIP and GISP2 ice cores. There is pre-Holocene ice near the bed. The change in delta18O since the last glacial maximum (LGM) is at least 12.5 per mil, compared with an expected value of 7 per mil, suggesting that LGM ice originated at the much higher elevations of the then existing Foxe Dome and Foxe Ridge of the Laurentide Ice Sheet. The LGM delta18O values suggest thick ice frozen to the bed of Hudson Bay.

  18. Msh2 deficiency leads to chromosomal abnormalities, centrosome amplification, and telomere capping defect

    SciTech Connect

    Wang, Yisong; Liu, Yie

    2006-01-01

    Msh2 is a key mammalian DNA mismatch repair (MMR) gene and mutations or deficiencies in mammalian Msh2 gene result in microsatellite instability (MSI+) and the development of cancer. Here, we report that primary mouse embryonic fibroblasts (MEFs) deficient in the murine MMR gene Msh2 (Msh2-/-) showed a significant increase in chromosome aneuploidy, centrosome amplification, and defective mitotic spindle organization and unequal chromosome segregation. Although Msh2-/- mouse tissues or primary MEFs had no apparent change in telomerase activity, telomere length, or recombination at telomeres, Msh2-/- MEFs showed an increase in chromosome end-to-end fusions or chromosome ends without detectable telomeric DNA. These data suggest that MSH2 helps to maintain genomic stability through the regulation of the centrosome and normal telomere capping in vivo and that defects in MMR can contribute to oncogenesis through multiple pathways.

  19. Impact of capped and uncapped abandoned leads on the heating of an MR-conditional pacemaker implant.

    PubMed

    Mattei, Eugenio; Gentili, Giulia; Censi, Federica; Triventi, Michele; Calcagnini, Giovanni

    2015-01-01

    To assess the risk of radiofrequency (RF)-induced heating in patients with MR-conditional pacemaker (PM) systems, in the presence of another lead abandoned from a previous implant. Four commercial pacemaker leads were placed beside a MR-conditional PM system, inside a human trunk simulator. The phantom has been exposed to the RF generated by a 64 MHz body bird-cage coil (whole-body specific absorption rate [SAR] = 1 W/kg) and the induced heating was measured at the tip of the abandoned lead and of the MR-conditional implant. Configurations that maximize the coupling between the RF field and the leads have been tested, as well as realistic implant positions. Abandoned leads showed heating behaviors that strongly depend on the termination condition (abandoned-capped or saline exposed) and on the lead path (left or right positioning). Given a whole-body SAR = 1 W/kg, a maximum temperature rise of 17.6°C was observed. The presence of the abandoned lead modifies the RF-heating profile of the MR-conditional implant: either an increase or a decrease in the induced heating at its lead tip can occur, mainly depending on the relative position of the two leads. Variations ranging from -63% to +69% with respect to the MR-conditional system alone were observed. These findings provide experimental evidence that the presence of an abandoned lead poses an additional risk for the patient implanted with a MR-conditional PM system. Our results support the current PM manufacturers' policy of conditioning the MR compatibility of their systems to the absence of abandoned leads (including leads from MR-conditional implants). From a clinical point of view, in such cases, the decision whether to perform the exam shall be based upon a risk/benefit evaluation, as in the case of conventional PM systems. © 2014 Wiley Periodicals, Inc.

  20. Ice core from Akademii Nauk ice cap, Severnaya Zemlya (Russian Arctic), dated with a Nye model modified for a growing glacier

    NASA Astrophysics Data System (ADS)

    Fritzsche, Diedrich; Opel, Thomas; Meyer, Hanno

    2010-05-01

    From 1999 to 2001 a 724 m deep ice core has been drilled from surface to bedrock close to summit of the Akademii Nauk ice cap, Severnaya Zemlya (Russian Arctic), within a joint German-Russian project. The analysis of stable water isotopes and major ion concentration in high resolution were used for reconstruction of past climate and environmental changes. The upper 304 m of the core were dated by counting annual stable isotope cycles considering radioactive (1986, 1963) and volcanic events (1956, 1912, 1783, 1259) as reference horizons. The resulting depth-age relationship and the corresponding annual-layer thickness imply that the ice cap was not in dynamic steady state but had been growing until recent times. That does not comply with requirements of a standard Nye or Dansgaard-Johnson flow model approach. To take into account the peculiarities of Akademii Nauk ice cap a Nye model was modified by adding a growing term according to the found relationship between annual layer thickness and depth. Using the volcanoes identified an average increase of altitude of about 0.08 m w.e. per year was calculated since AD 1259. The model enables us to reconstruct the altitude changes of the ice cap with time and to consider an altitude effect to correct the stable isotope values and to explain decreasing sea-salt ion data. Using the suggested model annual layer thickness can be decompressed to accumulation rates at the altitude where the precipitation was originally deposited. The model can also be used for dating deeper parts of ice core where volcanoes are not identified up to now. Applying this model, the ice core has an age of about 2 500 years, much less than claimed for an older core from Akademii Nauk ice cap. Consequently, the ice cap is much younger and only of Late Holocene age, as also assumed for most Arctic ice caps and glaciers outside Greenland. However, the lowest part of Akademii Nauk ice cap is probably a remnant of an older ice cap stage.

  1. Chronicling a century of lead pollution in Mexico: stable lead isotopic composition analyses of dated sediment cores.

    PubMed

    Soto-Jimenez, Martin F; Hibdon, Sharon A; Rankin, Charley W; Aggarawl, Jugdeep; Ruiz-Fernandez, A Carolina; Paez-Osuna, Federico; Flegal, A Russell

    2006-02-01

    Analyses of lead isotopic compositions (204Pb, 206Pb, 207Pb, and 208Pb) of dated sediment cores from two coastal estuaries and two inland lakes chronicle the predominance of industrial lead emissions in Mexico over the past century. These isotopic ratios exhibit a shift in composition from the turn of the previous century (1900) that corresponds with measurable increases (from 2- to 10-fold) in lead concentrations in the cores above their baseline values (3-22 microg/g)--both changes are consistent with the development of Mexican lead production for export and the manufacture of tetraethyl lead additives for Mexican gasolines. While subsequent changes in lead concentrations in the cores correspond with calculated emissions from the combustion of leaded gasoline in Mexico, isotopic compositions of the cores remain relatively constant throughout most of the 1900s (e.g., 206Pb/207Pb = 1.200 +/- 0.003; 208Pb/207Pb = 2.463 +/- 0.004). That isotopic constancy is attributed to the widespread pollution from lead production in Mexico and the dispersion of some of that lead used as an additive in Mexican gasolines.

  2. Effects of zinc, copper, and lead toxicity on. cap alpha. -aminolevulinic acid dehydratase activity. [Rats

    SciTech Connect

    Shafiq-ur-Rehman

    1984-07-01

    The distribution of lead, zinc and copper in the human environment has been recognized as a major toxicological factor. Lead ions have been shown to inhibit the activity of delta-aminolevulinic acid dehydratase (delta-ALAD), which is involved in the biosynthesis of heme. Copper also has its inhibitory effect on delta-ALAD activity. A study has shown that the delta-ALAD was activated by zinc ions at physiological concentrations. In view of these reports, it was considered worthwhile to study the poisoning effects of lead, zinc and copper on delta-ALAD activity along with the concentrations of these metal ions in the blood. A possible role of Zn/sup + +/, Cu/sup + +/, and Pb/sup + +/ interaction and their influence on delta-ALAD has been explored in the present paper.

  3. Highly efficient siRNA delivery from core-shell mesoporous silica nanoparticles with multifunctional polymer caps

    NASA Astrophysics Data System (ADS)

    Möller, Karin; Müller, Katharina; Engelke, Hanna; Bräuchle, Christoph; Wagner, Ernst; Bein, Thomas

    2016-02-01

    A new general route for siRNA delivery is presented combining porous core-shell silica nanocarriers with a modularly designed multifunctional block copolymer. Specifically, the internal storage and release of siRNA from mesoporous silica nanoparticles (MSN) with orthogonal core-shell surface chemistry was investigated as a function of pore-size, pore morphology, surface properties and pH. Very high siRNA loading capacities of up to 380 μg per mg MSN were obtained with charge-matched amino-functionalized mesoporous cores, and release profiles show up to 80% siRNA elution after 24 h. We demonstrate that adsorption and desorption of siRNA is mainly driven by electrostatic interactions, which allow for high loading capacities even in medium-sized mesopores with pore diameters down to 4 nm in a stellate pore morphology. The negatively charged MSN shell enabled the association with a block copolymer containing positively charged artificial amino acids and oleic acid blocks, which acts simultaneously as capping and endosomal release agent. The potential of this multifunctional delivery platform is demonstrated by highly effective cell transfection and siRNA delivery into KB-cells. A luciferase reporter gene knock-down of up to 80-90% was possible using extremely low cell exposures with only 2.5 μg MSN containing 0.5 μg siRNA per 100 μL well.A new general route for siRNA delivery is presented combining porous core-shell silica nanocarriers with a modularly designed multifunctional block copolymer. Specifically, the internal storage and release of siRNA from mesoporous silica nanoparticles (MSN) with orthogonal core-shell surface chemistry was investigated as a function of pore-size, pore morphology, surface properties and pH. Very high siRNA loading capacities of up to 380 μg per mg MSN were obtained with charge-matched amino-functionalized mesoporous cores, and release profiles show up to 80% siRNA elution after 24 h. We demonstrate that adsorption and desorption of

  4. A shallow ice core re-drilled on the Dunde Ice Cap, western China: recent changes in the Asian high mountains

    NASA Astrophysics Data System (ADS)

    Takeuchi, Nozomu; Miyake, Takayuki; Nakazawa, Fumio; Narita, Hideki; Fujita, Koji; Sakai, Akiko; Nakawo, Masayoshi; Fujii, Yoshiyuki; Duan, Keqin; Yao, Tandong

    2009-10-01

    A 51 m deep ice core was re-drilled on the Dunde Ice Cap of western China in 2002, 15 years after the previous ice core drilling in 1987. Dating by seasonal variations in δ18O and particle concentration showed that this 51 m deep ice core covered approximately the last 150 years. The stratigraphy and density showed that more than 90% of the ice core was refrozen ice layers, which comprised less than 5% of the annual accumulation in the older core. This indicates that the ice cap had experienced a more intense melting since 1987, possibly due to climate warming in this region. Mean net accumulation since the last drilling (2002-1987) was 176 mm a-1, which was considerably smaller than that obtained from the 1987 core (390 mm a-1, 1987-1963), indicating a significant decrease of net accumulation on the ice cap in the more recent period. The δ18O record showed an increasing trend in the late 19th century and the highest in the 1950s, which is consistent with the previous core findings. However, there has been no significant increase in δ18O during the last two decades, in contrast to the warming trends suggested by the melt features and other climate records. This discrepancy may be due to the modification of δ18O records by melt water runoff, percolation, and refreezing on the ice cap. Results strongly suggest recent significant mass loss of glaciers in the Asian high mountains and serious shortage of water supply for local people in this arid region in the near future.

  5. Green synthesis and characterization of size tunable silica-capped gold core-shell nanoparticles

    NASA Astrophysics Data System (ADS)

    Wangoo, Nishima; Shekhawat, Gajendra; Wu, Jin-Song; Bhasin, Aman K. K.; Suri, C. R.; Bhasin, K. K.; Dravid, Vinayak

    2012-08-01

    Silica-coated gold nanoparticles (Au@SiO2) with controlled silica-shell thickness were prepared by a modified Stober's method using 10-nm gold nanoparticles (AuNPs) as seeds. The AuNPs were silica-coated with a sol-gel reaction using tetraethylorthosilicate (TEOS) as a silica source and ammonia as a catalyst. An increase in TEOS concentration resulted in an increase in shell thickness. The NPs were characterized by transmission electron microscopy, selected area electron diffraction, energy-dispersive X-ray spectroscopy, scanning near-field ultrasound holography and scanning transmission electron microscopy. The method required no surface modification and the synthesized core shell nanoparticles can be used for various types of biological applications.

  6. MRI scanning in patients with new and existing CapSureFix Novus 5076 pacemaker leads: randomized trial results.

    PubMed

    Shenthar, Jayaprakash; Milasinovic, Goran; Al Fagih, Ahmed; Götte, Marco; Engel, Gregory; Wolff, Steven; Tse, Hung-Fat; Herr, Julie; Carrithers, John; Cerkvenik, Jeffrey; Nähle, Claas Philip

    2015-04-01

    Magnetic resonance imaging (MRI) can be safely performed in patients with magnetic resonance (MR)-conditional pacemaker systems but remains relatively contraindicated with non-MR-conditional pacemaker systems. The purpose of this study was to evaluate the safety of MRI without positioning restrictions in patients with an MR-conditional pacemaker and currently a non-MR-conditional Medtronic CapSureFix Novus 5076 lead(s). The study randomized 266 patients in a 2:1 ratio to the MRI group (177 patients) or to the control group (89 patients). At 9-12 weeks postimplant, the MRI group underwent MRI at 1.5 T. Primary end points were MRI-related complication-free rate and noninferiority of the MRI group compared to the control group with regard to the proportion of patients with an increase of ≤0.5 V in right atrial (RA) and right ventricular (RV) pacing capture thresholds from immediately before MRI to 1-month after MRI. No MRI-related complications occurred in 156 MRI-scanned patients who were followed through 1-month post-MRI. Differences in the proportion of patients with ≤0.5 V pacing capture threshold changes from pre-MRI to 1-month post-MRI were minimal between the groups for RA (proportions of 100% in both groups; a P value cannot be calculated) and RV leads (proportions of 99.3% in the MRI group and 100% in the control group; noninferiority test, P < .0001). Proportions of patients with acceptable sensing amplitude changes from pre-MRI to 1-month post-MRI were also similar between the 2 groups for RA and RV leads (noninferiority test, P < .0001 and P = .0004, respectively). No arrhythmias occurred during MRI. MRI scans can be performed safely without positioning restrictions in patients with Medtronic CapSureFix Novus 5076 leads connected to an MR-conditional pacemaker. Copyright © 2015 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.

  7. Randomized Controlled Trial of Radiation Protection With a Patient Lead Shield and a Novel, Nonlead Surgical Cap for Operators Performing Coronary Angiography or Intervention.

    PubMed

    Alazzoni, Ashraf; Gordon, Chris L; Syed, Jaffer; Natarajan, Madhu K; Rokoss, Michael; Schwalm, Jon-David; Mehta, Shamir R; Sheth, Tej; Valettas, Nicholas; Velianou, James; Pandie, Shaheen; Al Khdair, Darar; Tsang, Michael; Meeks, Brandi; Colbran, Kiersten; Waller, Ed; Fu Lee, Shun; Marsden, Tamara; Jolly, Sanjit S

    2015-08-01

    Interventional cardiologists receive one of the highest levels of annual occupational radiation exposure. Further measures to protect healthcare workers are needed. We evaluated the efficacy of a pelvic lead shield and a novel surgical cap in reducing operators' radiation exposure. Patients undergoing coronary angiography or percutaneous coronary intervention (n=230) were randomized to have their procedure with or without a lead shield (Ultraray Medical, Oakville, Canada) placed over the patient. During all procedures, operators wore the No Brainer surgical cap (Worldwide Innovations and Technology, Kansas City, KS) designed to protect the head from radiation exposure. The coprimary outcomes for the lead shield comparison were (1) operator dose (µSv) and (2) operator dose indexed for air kerma (µSv/mGy). For the cap comparison, the primary outcome was the difference between total radiation dose (µSv; internal and external to cap). The lead shield use resulted in a 76% reduction in operator dose (mean dose, 3.07; 95% confidence interval [CI], 2.00-4.71 µSv lead shield group versus 12.57; 95% CI, 8.14-19.40 µSv control group; P<0.001). The mean dose indexed for air kerma was reduced by 72% (0.004; 95% CI, 0.003-0.005 µSv/mGy lead shield group versus 0.015; 95% CI, 0.012-0.019 µSv/mGy control group; P<0.001). The cap use resulted in a significant reduction in operator head radiation exposure (mean left temporal difference [external-internal] radiation dose was 4.79 [95% CI, 3.30-6.68] µSv; P<0.001). The use of a pelvic lead shield and the cap reduced significantly the operator radiation exposure and can be easily incorporated into clinical practice. URL: http://www.clinicaltrials.gov. Unique identifier: NCT02128035. © 2015 American Heart Association, Inc.

  8. Lead is probably not in the core after all

    NASA Astrophysics Data System (ADS)

    Albarede, F.

    2010-12-01

    The possibility that planetary Pb segregated into planetary cores was first suggested by A.E. Ringwood [1] 50 years ago and the debate has continued unresolved in the literature ever since. It is well understood that sequestration of substantial amounts of Pb in metal dramatically affects the interpretation of the Pb planetary isotopic record, which, since Pb only condenses from the nebula at temperatures ≤ 700 K, in turn affects the understanding of volatiles in terrestrial planets [2]. ‘Core pumping’, however, conflicts with both metallurgical evidence and the very low Pb concentrations observed in iron meteorites [3]. Wood and Halliday [4] (thereafter WH) recently reported new metal/silicate equilibration experiments in which Pb is inferred to substantially partition into liquid metal. I here argue that this favorable partitioning is simply an artifact of Pb and Fe unmixing due to the extraordinary large Pb concentrations (>1000 times the chondritic abundances) used in Wood et al.’s experiments and that this dataset is not pertinent to the natural planetary environment. The Fe-Pb binary diagram has been the subject of metallurgical interest and although the data are rather old, the consensus is that liquid Pb and Fe are almost immiscible [5-7]. The Lord and Parlee’s [6] data set was acquired under the liquid-liquid equilibration conditions of WH, but, unfortunately, the range of temperature only partially overlap. WH’s relation between concentration data plotted and temperature can, however, be compared with the Pb solubility data in liquid Fe and their extrapolation using a standard thermodynamic equation for the miscibility loop ln X = A/T +B [5]. In this equation, X stands for the Pb concentration in liquid Fe and A and B are constants holding information on the enthalpy and entropy of mixing. Wood and Halliday added 3000 ppm Pb to their experimental charges and acknowledge the presence of widespread liquid micrometer-sized Pb droplets, which they

  9. Over-expression of Arabidopsis CAP causes decreased cell expansion leading to organ size reduction in transgenic tobacco plants.

    PubMed

    Barrero, Roberto A; Umeda, Masaaki; Yamamura, Saburo; Uchimiya, Hirofumi

    2003-04-01

    Cyclase-associated proteins (CAP) are multifunctional proteins involved in Ras-cAMP signalling and regulation of the actin cytoskeleton. It has recently been demonstrated that over-expression of AtCAP1 in transgenic arabidopsis plants causes severe morphological defects owing to loss of actin filaments. To test the generality of the function of AtCAP1 in plants, transgenic tobacco plants over-expressing an arabidopsis CAP (AtCAP1) under the regulation of a glucocorticoid-inducible promoter were produced. Over-expression of AtCAP1 in transgenic tobacco plants led to growth abnormalities, in particular a reduction in the size of leaves. Morphological alterations in leaves were the result of reduced elongation of epidermal and mesophyll cells.

  10. The lead isotopic age of the Earth can be explained by core formation alone.

    PubMed

    Wood, Bernard J; Halliday, Alex N

    2010-06-10

    The meaning of the age of the Earth defined by lead isotopes has long been unclear. Recently it has been proposed that the age of the Earth deduced from lead isotopes reflects volatile loss to space at the time of the Moon-forming giant impact rather than partitioning into metallic liquids during protracted core formation. Here we show that lead partitioning into liquid iron depends strongly on carbon content and that, given a content of approximately 0.2% carbon, experimental and isotopic data both provide evidence of strong partitioning of lead into the core throughout the Earth's accretion. Earlier conclusions that lead is weakly partitioned into iron arose from the use of carbon-saturated (about 5% C) iron alloys. The lead isotopic age of the Earth is therefore consistent with partitioning into the core and with no significant late losses of moderately volatile elements to space during the giant impact.

  11. The CAP cancer protocols – a case study of caCORE based data standards implementation to integrate with the Cancer Biomedical Informatics Grid

    PubMed Central

    Tobias, Jonathan; Chilukuri, Ram; Komatsoulis, George A; Mohanty, Sambit; Sioutos, Nicholas; Warzel, Denise B; Wright, Lawrence W; Crowley, Rebecca S

    2006-01-01

    Background The Cancer Biomedical Informatics Grid (caBIG™) is a network of individuals and institutions, creating a world wide web of cancer research. An important aspect of this informatics effort is the development of consistent practices for data standards development, using a multi-tier approach that facilitates semantic interoperability of systems. The semantic tiers include (1) information models, (2) common data elements, and (3) controlled terminologies and ontologies. The College of American Pathologists (CAP) cancer protocols and checklists are an important reporting standard in pathology, for which no complete electronic data standard is currently available. Methods In this manuscript, we provide a case study of Cancer Common Ontologic Representation Environment (caCORE) data standard implementation of the CAP cancer protocols and checklists model – an existing and complex paper based standard. We illustrate the basic principles, goals and methodology for developing caBIG™ models. Results Using this example, we describe the process required to develop the model, the technologies and data standards on which the process and models are based, and the results of the modeling effort. We address difficulties we encountered and modifications to caCORE that will address these problems. In addition, we describe four ongoing development projects that will use the emerging CAP data standards to achieve integration of tissue banking and laboratory information systems. Conclusion The CAP cancer checklists can be used as the basis for an electronic data standard in pathology using the caBIG™ semantic modeling methodology. PMID:16787533

  12. Emissions of lead and zinc from candles with metal-core wicks.

    PubMed

    Nriagu, J O; Kim, M J

    2000-04-24

    We measured the amount of lead released from 14 different brands of candles with metal-core wicks sold in Michigan. The emissions of lead were found to range from 0.5 to 66 microg/h, and the rates for zinc were from 1.2 to 124 microg/h. It is estimated that burning four of the candles bought in Michigan for 2 h can result in airborne lead concentrations that can pose a threat to human health. In addition to inhalation of lead in the air, children get exposed to lead in candle fumes deposited on the floor, furniture and walls through their hand-to-mouth activity. Burning candles with leaded-core wick may be an important exposure route for lead that has generally been ignored.

  13. Numerical prediction of vortex cores of the leading and trailing edges of delta wings

    NASA Technical Reports Server (NTRS)

    Kandil, O. A.

    1980-01-01

    The purpose of the present paper is to predict the roll-up of the vortex sheets emanating from the leading- and trailing-edges of delta wings with emphasis on the interaction of vortex cores beyond the trailing edge. The motivation behind the present work is the recent experimental data published by Hummel. The Nonlinear Discrete-Vortex method (NDV-method) is modified and extended to predict the leading- and trailing-vortex cores beyond the trailing edge. The present model alleviates the problems previously encountered in predicting satisfactory pressure distributions. This is accomplished by lumping the free-vortex lines during the iteration procedure. The leading- and trailing-edge cores and their feeding sheets are obtained as parts of the solution. The numerical results show that the NDV-method is successful in confirming the formation of a trailing-edge core with opposite circulation and opposite roll-up to those of the leading-edge core. This work is a breakthrough in the high angle of attack aerodynamics and moreover, it is the first numerical prediction done on this problem

  14. Glycerol capped PbS/CdS core/shell nanoparticles at different molar ratio and its application in biosensors: An optical properties study

    SciTech Connect

    Das, D. Hussain, A. M. P.

    2016-05-06

    Glycerol capped PbS/CdS core/shell type nanoparticles fabricated with two different molar ratios are characterized for study of structural and optical properties. The X-ray diffraction (XRD) pattern exhibits cubic phased polycrystalline nanocrystals. The calculated grain sizes from Williamson-Hall plot were found to be around 6 nm with increased strain. HRTEM investigation confirms the formation of core/shell nanostructures and the sizes of the particles were found to be around 7 nm which is in good agreement with the results of the W-H plot. An increase of band gap with the decrease in precursor concentration is confirmed from the blue shift in the absorption spectra and also from Tauc plot. A clear blue shifted intense emission is observed in the photoluminescence spectra with decrease in particle size. Intense luminescence from the core/shell nanostructure may be applied in bio labelling and biosensors.

  15. Glycerol capped PbS/CdS core/shell nanoparticles at different molar ratio and its application in biosensors: An optical properties study

    NASA Astrophysics Data System (ADS)

    Das, D.; Hussain, A. M. P.

    2016-05-01

    Glycerol capped PbS/CdS core/shell type nanoparticles fabricated with two different molar ratios are characterized for study of structural and optical properties. The X-ray diffraction (XRD) pattern exhibits cubic phased polycrystalline nanocrystals. The calculated grain sizes from Williamson-Hall plot were found to be around 6 nm with increased strain. HRTEM investigation confirms the formation of core/shell nanostructures and the sizes of the particles were found to be around 7 nm which is in good agreement with the results of the W-H plot. An increase of band gap with the decrease in precursor concentration is confirmed from the blue shift in the absorption spectra and also from Tauc plot. A clear blue shifted intense emission is observed in the photoluminescence spectra with decrease in particle size. Intense luminescence from the core/shell nanostructure may be applied in bio labelling and biosensors.

  16. A Computer-Simulation Study on the Effects of MRI Voxel Dimensions on Carotid Plaque Lipid-Core and Fibrous Cap Segmentation and Stress Modeling

    PubMed Central

    Nieuwstadt, Harm A.; Kassar, Zaid A. M.; van der Lugt, Aad; Breeuwer, Marcel; van der Steen, Anton F. W.; Wentzel, Jolanda J.; Gijsen, Frank J. H.

    2015-01-01

    Background The benefits of a decreased slice thickness and/or in-plane voxel size in carotid MRI for atherosclerotic plaque component quantification accuracy and biomechanical peak cap stress analysis have not yet been investigated in detail because of practical limitations. Methods In order to provide a methodology that allows such an investigation in detail, numerical simulations of a T1-weighted, contrast-enhanced, 2D MRI sequence were employed. Both the slice thickness (2 mm, 1 mm, and 0.5 mm) and the in plane acquired voxel size (0.62x0.62 mm2 and 0.31x0.31 mm2) were varied. This virtual MRI approach was applied to 8 histology-based 3D patient carotid atherosclerotic plaque models. Results A decreased slice thickness did not result in major improvements in lumen, vessel wall, and lipid-rich necrotic core size measurements. At 0.62x0.62 mm2 in-plane, only a 0.5 mm slice thickness resulted in improved minimum fibrous cap thickness measurements (a 2–3 fold reduction in measurement error) and only marginally improved peak cap stress computations. Acquiring voxels of 0.31x0.31 mm2 in-plane, however, led to either similar or significantly larger improvements in plaque component quantification and computed peak cap stress. Conclusions This study provides evidence that for currently-used 2D carotid MRI protocols, a decreased slice thickness might not be more beneficial for plaque measurement accuracy than a decreased in-plane voxel size. The MRI simulations performed indicate that not a reduced slice thickness (i.e. more isotropic imaging), but the acquisition of anisotropic voxels with a relatively smaller in-plane voxel size could improve carotid plaque quantification and computed peak cap stress accuracy. PMID:25856094

  17. Creation of Novel Cores for β-Secretase (BACE-1) Inhibitors: A Multiparameter Lead Generation Strategy.

    PubMed

    Viklund, Jenny; Kolmodin, Karin; Nordvall, Gunnar; Swahn, Britt-Marie; Svensson, Mats; Gravenfors, Ylva; Rahm, Fredrik

    2014-04-10

    In order to find optimal core structures as starting points for lead optimization, a multiparameter lead generation workflow was designed with the goal of finding BACE-1 inhibitors as a treatment for Alzheimer's disease. De novo design of core fragments was connected with three predictive in silico models addressing target affinity, permeability, and hERG activity, in order to guide synthesis. Taking advantage of an additive SAR, the prioritized cores were decorated with a few, well-characterized substituents from known BACE-1 inhibitors in order to allow for core-to-core comparisons. Prediction methods and analyses of how physicochemical properties of the core structures correlate to in vitro data are described. The syntheses and in vitro data of the test compounds are reported in a separate paper by Ginman et al. [J. Med. Chem. 2013, 56, 4181-4205]. The affinity predictions are described in detail by Roos et al. [J. Chem. Inf. 2014, DOI: 10.1021/ci400374z].

  18. An ultra-clean firn core from the Devon Island Ice Cap, Nunavut, Canada, retrieved using a titanium drill specially designed for trace element studies.

    PubMed

    Zheng, J; Fisher, D; Blake, E; Hall, G; Vaive, J; Krachler, M; Zdanowicz, C; Lam, J; Lawson, G; Shotyk, W

    2006-03-01

    An electromechanical drill with titanium barrels was used to recover a 63.7 m long firn core from Devon Island Ice Cap, Nunavut, Canada, representing 155 years of precipitation. The core was processed and analysed at the Geological Survey of Canada by following strict clean procedures for measurements of Pb and Cd at concentrations at or below the pg g(-1) level. This paper describes the effectiveness of the titanium drill with respect to contamination during ice core retrieval and evaluates sample-processing procedures in laboratories. The results demonstrate that: (1) ice cores retrieved with this titanium drill are of excellent quality with metal contamination one to four orders of magnitude less than those retrieved with conventional drills; (2) the core cleaning and sampling protocols used were effective, contamination-free, and adequate for analysis of the metals (Pb and Cd) at low pg g(-1) levels; and (3) results from 489 firn core samples analysed in this study are comparable with published data from other sites in the Arctic, Greenland and the Antarctic.

  19. Core Practices and Problems of Practice in Learning to Lead Classroom Discussions

    ERIC Educational Resources Information Center

    Ghousseini, Hala

    2015-01-01

    Given the current interest in organizing teacher education around core instructional practices that help preservice teachers enact ambitious aspects of teaching like leading classroom discussions, this article investigates an example from the experience of a preservice teacher as she works on orienting students to each other's ideas. Resulting…

  20. Core Practices and Problems of Practice in Learning to Lead Classroom Discussions

    ERIC Educational Resources Information Center

    Ghousseini, Hala

    2015-01-01

    Given the current interest in organizing teacher education around core instructional practices that help preservice teachers enact ambitious aspects of teaching like leading classroom discussions, this article investigates an example from the experience of a preservice teacher as she works on orienting students to each other's ideas. Resulting…

  1. Mechanochemical approach for the capping of mixed core CdS/ZnS nanocrystals: Elimination of cadmium toxicity.

    PubMed

    Bujňáková, Zdenka; Baláž, Matej; Dutková, Erika; Baláž, Peter; Kello, Martin; Mojžišová, Gabriela; Mojžiš, Ján; Vilková, Mária; Imrich, Ján; Psotka, Miroslav

    2017-01-15

    The wet mechanochemical procedure for the capping of the CdS and CdS/ZnS quantum dot nanocrystals is reported. l-cysteine and polyvinylpyrrolidone (PVP) were used as capping agents. When using l-cysteine, the dissolution of cadmium(II) was almost none for CdS/ZnS nanocrystals. Moreover, prepared CdS- and CdS/ZnS-cysteine nanosuspensions exhibited unimodal particle size distributions with very good stability, which was further supported by the zeta potential measurements. The Fourier-transform infrared (FTIR) and nuclear magnetic resonance (NMR) spectroscopy showed the successful embedment of cysteine into the structure of the nanocrystals. Additionally, the optical properties were examined, and the results showed that the cysteine nanosuspension has promising fluorescence properties. On the other hand, PVP was not determined to be a very suitable capping agent for the present system. In this case, the release of cadmium(II) was higher in comparison to the l-cysteine capped samples. The nanosuspensions were successfully used for in vitro studies on selected cancer cell lines. Using fluorescence microscopy, it was evidenced that the nanocrystals enter the cell and that they can serve as imaging agents in biomedical applications. Copyright © 2016. Published by Elsevier Inc.

  2. A theory for the core of a three-dimensional leading-edge vortex

    NASA Technical Reports Server (NTRS)

    Luckring, J. M.

    1985-01-01

    A theory is presented for the flow in the core of a separation-induced leading-edge vortex. The theory is based on matching inner and outer representations of the vortex. The inner representation models continuously distributed vorticity and includes an asymptotic viscous subcore. The outer representation models concentrated spiral sheets of vorticity and is fully three dimensional. A parameter is identified which closely tracks the vortex breakdown stability boundary for delta, arrow, and diamond wings.

  3. Atmospheric deposition of current use pesticides in the Arctic: snow core records from the Devon Island Ice Cap, Nunavut, Canada.

    PubMed

    Zhang, Xianming; Meyer, Torsten; Muir, Derek C G; Teixeira, Camilla; Wang, Xiaowa; Wania, Frank

    2013-12-01

    Current use pesticides (CUPs) have been detected in the Arctic, even though there are no direct sources and their long range atmospheric transport potential is generally lower than that of legacy pesticides. Data on the deposition of CUPs in the Arctic are required to assess the impact of their global usage and emission. In this study, selected CUPs were measured in the layers of a snow pit sampled on the Devon Ice Cap, Nunavut, Canada. The oldest sampled layers correspond to deposition from the early 1990s. Dacthal and endosulfan sulfate were most frequently detected, with peak deposition fluxes of 1.0 and 0.4 pg cm(-2) per year. While endosulfan sulfate was more abundant than its parent compounds in most years, endosulfan (sum of α and β isomers) was predominant in 2003 and 2006, which together with air mass backward trajectories suggests a possible origin from ongoing use in Eurasia. The interannual variation in CUP deposition fluxes could not be explained with annual variations in the extent of air mass origin over agricultural lands, suggesting that other factors, such as the interannual variation in pesticide use, play a role in affecting the long range transport of CUPs to the Arctic. The very high variability in the concentrations of CUPs in the horizontal layers of Arctic ice caps is most plausibly explained by the highly episodic nature of long range atmospheric transport and deposition. While this strong influence of rare events limits the suitability of ice caps as reliable records of historical trends in Arctic contaminant deposition with annual resolution, the presence of concentration peaks in the ice record is proof of the possibility of such transport and deposition.

  4. Model-based cap thickness and peak cap stress prediction for carotid MRI.

    PubMed

    Kok, Annette M; van der Lugt, Aad; Verhagen, Hence J M; van der Steen, Antonius F W; Wentzel, Jolanda J; Gijsen, Frank J H

    2017-07-26

    A rupture-prone carotid plaque can potentially be identified by calculating the peak cap stress (PCS). For these calculations, plaque geometry from MRI is often used. Unfortunately, MRI is hampered by a low resolution, leading to an overestimation of cap thickness and an underestimation of PCS. We developed a model to reconstruct the cap based on plaque geometry to better predict cap thickness and PCS. We used histological stained plaques from 34 patients. These plaques were segmented and served as the ground truth. Sections of these plaques contained 93 necrotic cores with a cap thickness <0.62mm which were used to generate a geometry-based model. The histological data was used to simulate in vivo MRI images, which were manually delineated by three experienced MRI readers. Caps below the MRI resolution (n=31) were (digitally removed and) reconstructed according to the geometry-based model. Cap thickness and PCS were determined for the ground truth, readers, and reconstructed geometries. Cap thickness was 0.07mm for the ground truth, 0.23mm for the readers, and 0.12mm for the reconstructed geometries. The model predicts cap thickness significantly better than the readers. PCS was 464kPa for the ground truth, 262kPa for the readers and 384kPa for the reconstructed geometries. The model did not predict the PCS significantly better than the readers. The geometry-based model provided a significant improvement for cap thickness estimation and can potentially help in rupture-risk prediction, solely based on cap thickness. Estimation of PCS estimation did not improve, probably due to the complex shape of the plaques. Copyright © 2017 The Author(s). Published by Elsevier Ltd.. All rights reserved.

  5. Core-level spectra and binding energies of transition metal nitrides by non-destructive x-ray photoelectron spectroscopy through capping layers

    NASA Astrophysics Data System (ADS)

    Greczynski, G.; Primetzhofer, D.; Lu, J.; Hultman, L.

    2017-02-01

    We present the first measurements of x-ray photoelectron spectroscopy (XPS) core level binding energies (BE:s) for the widely-applicable group IVb-VIb polycrystalline transition metal nitrides (TMN's) TiN, VN, CrN, ZrN, NbN, MoN, HfN, TaN, and WN as well as AlN and SiN, which are common components in the TMN-based alloy systems. Nitride thin film samples were grown at 400 °C by reactive dc magnetron sputtering from elemental targets in Ar/N2 atmosphere. For XPS measurements, layers are either (i) Ar+ ion-etched to remove surface oxides resulting from the air exposure during sample transfer from the growth chamber into the XPS system, or (ii) in situ capped with a few nm thick Cr or W overlayers in the deposition system prior to air-exposure and loading into the XPS instrument. Film elemental composition and phase content is thoroughly characterized with time-of-flight elastic recoil detection analysis (ToF-E ERDA), Rutherford backscattering spectrometry (RBS), and x-ray diffraction. High energy resolution core level XPS spectra acquired with monochromatic Al Kα radiation on the ISO-calibrated instrument reveal that even mild etching conditions result in the formation of a nitrogen-deficient surface layer that substantially affects the extracted binding energy values. These spectra-modifying effects of Ar+ ion bombardment increase with increasing the metal atom mass due to an increasing nitrogen-to-metal sputter yield ratio. The superior quality of the XPS spectra obtained in a non-destructive way from capped TMN films is evident from that numerous metal peaks, including Ti 2p, V 2p, Zr 3d, and Hf 4f, exhibit pronounced satellite features, in agreement with previously published spectra from layers grown and analyzed in situ. In addition, the N/metal concentration ratios are found to be 25-90% higher than those obtained from the corresponding ion-etched surfaces, and in most cases agree very well with the RBS and ToF-E ERDA values. The N 1 s BE:s extracted from

  6. Diatom ooze as weak layer for submarine mega-slides off Northwest Africa: Evidence from core-seismic integration in the Cap Blanc Slide area

    NASA Astrophysics Data System (ADS)

    Urlaub, Morelia; Geersen, Jacob; Krastel, Sebastian; Schwenk, Tilmann

    2017-04-01

    The continental slope off Northwest Africa has experienced at least four mega-landslides, each affecting over 20,000 km2 of seafloor. Although the landslides lie more than 400 km apart, they have many similar characteristics, including stepped headwall patterns and several bedding-parallel glide planes at slope angles of <2°. This morphology suggests that failures took place along multiple mechanically weak sedimentary layers that are present at different stratigraphic depths. From all Northwest African mega-landslides the Cap Blanc Slide, situated off the coasts of Mauretania and West Sahara, offers an unprecedented possibility to advance our understanding of landslide causes. ODP site 658 (Leg 108) was drilled within the evacuation area of the slide, recovering its glide plane. In addition, site 658 also recovered the glide plane and the overlying undisturbed sedimentary sequence of a younger slope failure, which took place within the evacuation are of the main Cap Blanc Slide at some distance to the borehole. We use core-seismic integration to characterize the glide planes as well as to determine the timing of slope failures. The sediments just above both glide planes have particularly high biogenic opal contents owing to the presence of large amounts of diatom microfossils. Diatoms are hollow structures of microfossil skeletons, which contain large amounts of bound and intraskeletal water. When a critical stress level is exceeded during compaction, the microfossil shells break. The stored water is released causing a sudden increase in pore pressure, which may facilitate slope failure. We therefore suggest that diatom oozes acted as weak layers in the case of the Cap Blanc Slide. Pronounced biogenic opal maxima occur during glacial terminations and are expected all along the Northwest African continental margin. We thus hypothesize that mega-slides off Northwest Africa, and potentially also at other continental margins, are preconditioned by episodically high

  7. Climate Changes Documented in Ice Core Records from Third Pole Glaciers, with Emphasis on the Guliya Ice Cap in the Western Kunlun Mountains over the Last 100 Years

    NASA Astrophysics Data System (ADS)

    Thompson, L. G.; Yao, T.; Beaudon, E.; Mosley-Thompson, E.; Davis, M. E.; Kenny, D. V.; Lin, P. N.

    2016-12-01

    The Third Pole (TP) is a rapidly warming region containing 100,000 km2 of ice cover that collectively holds one of Earth's largest stores of freshwater that feeds Asia's largest rivers and helps sustain 1.5 billion people. Information on the accelerating warming in the region, its impact on the glaciers and subsequently on future water resources is urgently needed to guide mitigation and adaptation policies. Ice core histories collected over the last three decades across the TP demonstrate its climatic complexity and diversity. Here we present preliminary results from the flagship project of the Third Pole Environment Program, the 2015 Sino-American cooperative ice core drilling of the Guliya ice cap in the Kunlun Mountains in the western TP near the northern limit of the region influenced by the southwest monsoon. Three ice cores, each 51 meters in length, were recovered from the summit ( 6700 masl) while two deeper cores, one to bedrock ( 310 meters), were recovered from the plateau ( 6200 masl). Across the ice cap the net balance (accumulation) has increased annually by 2.3 cm of water equivalent from 1963-1992 to 1992-2015, and average oxygen isotopic ratios (δ18O) have enriched by 2‰. This contrasts with the recent ablation on the Naimona'nyi glacier located 540 km south of Guliya in the western Himalaya. Borehole temperatures in 2015 on the Guliya plateau have warmed substantially in the upper 30 meters of the ice compared to temperatures in 1992, when the first deep-drilling of the Guliya plateau was conducted. Compared with glaciers in the northern and western TP, the Himalayan ice fields are more sensitive to both fluctuations in the South Asian Monsoon and rising temperatures in the region. We examine the climatic changes of the last century preserved in ice core records from sites throughout the TP and compare them with those reconstructed for earlier warm epochs, such as the Medieval Climate Anomaly ( 950-1250 AD), the early Holocene "Hypsithermal

  8. Introduction of the human pro. cap alpha. 1(I) collagen gene into pro. cap alpha. 1(I)-deficient Mov-13 mouse cells leads to formation of functional mouse-human hybrid type I collagen

    SciTech Connect

    Schnieke, A.; Dziadek, M.; Bateman, J.; Mascara, T.; Harbers, K.; Gelinas, R.; Jaenisch, R.

    1987-02-01

    The Mov-13 mouse strain carries a retroviral insertion in the pro..cap alpha..1(I) collagen gene that prevents transcription of the gene. Cell lines derived from homozygous embryos do not express type I collagen although normal amounts of pro..cap alpha..2 mRNA are synthesized. The authors have introduced genomic clones of either the human or mouse pro..cap alpha..1(I) collagen gene into homozygous cell lines to assess whether the human or mouse pro..cap alpha..1(I) chains can associate with the endogenous mouse pro..cap alpha..2(I) chain to form stable type I collagen. The human gene under control of the simian virus 40 promoter was efficiently transcribed in the transfected cells. Protein analyses revealed that stable heterotrimers consisting of two human ..cap alpha..1 chains and one mouse ..cap alpha..2 chain were formed and that type I collagen was secreted by the transfected cells at normal rates. However, the electrophoretic migration of both ..cap alpha..1(I) and ..cap alpha..2(I) chains in the human-mouse hybrid molecules were retarded, compared to the ..cap alpha..(I) chains in control mouse cells. Inhibition of the posttranslational hydroxylation of lysine and proline resulted in comigration of human and mouse ..cap alpha..1 and ..cap alpha..2 chains, suggesting that increased posttranslational modification caused the altered electrophoretic migration in the human-mouse hybrid molecules. Amino acid sequence differences between the mouse and human ..cap alpha.. chains may interfere with the normal rate of helix formation and increase the degree of posttranslational modifications similar to those observed in patients with lethal perinatal osteogenesis imperfecta. The Mov-13 mouse system should allow the authors to study the effect specific mutations introduced in transfected pro..cap alpha..1(I) genes have on the synthesis, assembly, and function of collagen I.

  9. Absolute kinematics of radio-source components in the complete S5 polar cap sample. IV. Proper motions of the radio cores over a decade and spectral properties

    NASA Astrophysics Data System (ADS)

    Martí-Vidal, I.; Abellán, F. J.; Marcaide, J. M.; Guirado, J. C.; Pérez-Torres, M. A.; Ros, E.

    2016-11-01

    We have carried out a high-precision astrometric analysis of two very-long-baseline-interferometry (VLBI) epochs of observation of the 13 extragalactic radio sources in the complete S5 polar cap sample. The VLBI epochs span a time baseline of ten years and enable us to achieve precisions in the proper motions of the source cores up to a few micro-arcseconds per year. The observations were performed at 14.4 GHz and 43.1 GHz, and enable us to estimate the frequency core-shifts in a subset of sources, for which the spectral-index distributions can be computed. We study the source-position stability by analysing the changes in the relative positions of fiducial source points (the jet cores) over a decade. We find motions of 0.1-0.9 mas among close-by sources between the two epochs, which imply drifts in the jet cores of approximately a few tens of μas per year. These results have implications for the standard Active Galactic Nucleus (AGN) jet model (where the core locations are supposed to be stable in time). For one of our sources, 0615+820, the morphological and spectral properties in year 2010, as well as the relative astrometry between years 2000 and 2010, suggest the possibility of either a strong parsec-scale interaction of the AGN jet with the ISM, a gravitational lens with 1 mas diameter, or a resolved massive binary black hole. Reduced images as FITS files are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/596/A27

  10. A theory for the core flow of leading-edge vortices

    NASA Technical Reports Server (NTRS)

    Luckring, James M.

    1986-01-01

    Separation-induced leading-edge vortices can dominate the flow about slender wings at moderate to high angles of attack, often with favorable aerodynamic effects. However, at the high angles of attack which are desirable for takeoff and landing as well as subsonic-transonic maneuver the vortices can breakdown or burst in the vicinity of the aircraft causing many adverse effects; these include lift loss, pitchup, and buffet. The flow in the core of leading-edge vortices is generally affiliated with the vortex breakdown phenomenon. A theory is presented for the flow in the core of separation-induced, leading-edge vortices at practical Reynolds numbers. The theory is based on matching inner and outer representations of the vortex. The inner representation models continuously distributed vorticity and includes an asymptotic viscous subcore. The outer representation models concentrated spiral sheets of vorticity and is fully three dimensional. A parameter is identified which closely tracks the vortex breakdown stability boundary for delta, arrow, and diamond wings.

  11. Investigating the preservation of nitrate isotopic composition in a tropical ice core from the Quelccaya Ice Cap, Peru

    NASA Astrophysics Data System (ADS)

    Buffen, Aron M.; Hastings, Meredith G.; Thompson, Lonnie G.; Mosley-Thompson, Ellen

    2014-03-01

    The nitrogen and oxygen isotopic composition of nitrate in ice cores offers unique potential for examining reactive nitrogen oxide (NOx) budgets and oxidation chemistry of past atmospheres. A low-latitude record is of particular interest given that the dominant natural sources of NOx and production of hydroxyl radical are most prevalent in the tropics. Any interpretation of nitrate in ice cores, however, must first consider that nitrate in snow is vulnerable to postdepositional loss and isotopic alteration. We report and assess the integrity of nitrate-δ15N, -δ18O, and -Δ17O in a 30 m ice core from a high-elevation site in the central Andes. Clear seasonality in δ15N, δ18O, and nitrate concentration exists throughout most of the record and cannot be explained by photolysis or evaporation based on our current understanding of these processes. In contrast, nitrate in the upper ~12 m of the core and in a snowpit shows very different behavior. This may reflect alteration facilitated by recent melting at the surface. The relationships between δ15N, δ18O, Δ17O, and concentration in the unaltered sections can be interpreted in terms of mixing of nitrate from discrete sources. Transport effects and an englacial contribution from nitrification cannot be ruled out at this time, but the observed isotopic compositions are consistent with expected signatures of known NOx sources and atmospheric oxidation pathways. Specifically, nitrate deposited during the wet season reflects biogenic soil emissions and hydroxyl/peroxy radical chemistry in the Amazon, while dry season deposition reflects a lightning source and ozone chemistry at higher levels in the troposphere.

  12. The GUINEVERE experiment: First PNS measurements in a lead moderated sub-critical fast core

    SciTech Connect

    Thyebault, H. E.; Billebaud, A.; Chabod, S.; Lecolley, F. R.; Lecouey, J. L.; Lehaut, G.; Marie, N.; Ban, G.

    2012-07-01

    The GUINEVERE (Generation of Uninterrupted Intense Neutrons at the lead Venus Reactor) experimental program is dedicated to the study of Accelerator Driven System reactivity monitoring. It was partly carried out within the EUROTRANS integrated project (EURATOM FP6). GUINEVERE consists in coupling the fast core of the VENUS-F reactor (SCK-CEN, Mol (Belgium)), composed of enriched uranium and solid lead, with a T(d,n) neutron source provided by the GENEPI-3C deuteron accelerator. This neutron source can be operated in several modes: pulsed mode, continuous mode and also continuous mode with short beam interruptions (the so called 'beam trips'). In the past, the key questions of the reactivity control and monitoring in a subcritical system were studied in the MUSE experiments (1998-2004). These experiments highlighted the difficulty to determine precisely the reactivity with a single technique. This led to investigate a new strategy which is based on the combination of the relative reactivity monitoring via the core power to beam current relationship with absolute reactivity cross-checks during programmed beam interruptions. Consequently, to determine the reactivity, several dynamical techniques of reactivity determination have to be compared. In addition, their accuracy for absolute reactivity determination must be evaluated using a reference reactivity determination technique (from a critical state: rod drop and MSM measurements). The first sub-critical configuration which was studied was around k{sub eff} = 0.96 (SCI). Pulsed Neutron Source experiments (PNS) were carried out. The neutron population decrease was measured using fission chambers in different locations inside the core and the reflector. Neutron population time decrease was analyzed using fitting techniques and the Area Method Results obtained for the SCI reactivity will be shown, discussed and compared to the reference value given by the MSM method. (authors)

  13. Cervical Cap

    MedlinePlus

    ... and remove the cap. How Much Does It Cost? A cervical cap costs about $70 and should be replaced every year. In addition, there is also the cost of the doctor's visit. Many health insurance plans ...

  14. Dissolution kinetics and physical characterization of three-layered tablet with poly(ethylene oxide) core matrix capped by Carbopol.

    PubMed

    Hong, Sung In; Oh, Seaung Youl

    2008-05-22

    We have prepared poly(ethylene oxide) (PEO) tablets which have three-layered structure by direct compression. Carbopol (CP) was coated on both sides of the central PEO matrix which contains solid-dispersed nifedipine (NP) in PEG4000. For comparison, physical mixture of PEO with poly(ethylene glycol 4000) (PEG4000) solid dispersion was also prepared. The differential scanning calorimetry (DSC) thermogram and X-ray diffraction (XRD) pattern obtained after 4 weeks of storage indicated that the crystallinity of PEG4000 in solid dispersion only slightly increased upon aging during this storage period. The formation of crystalline domain of NP, PEO or sodium dodecyl sulfate (SDS) was not observed. CP layers decreased the surface area exposed to dissolution medium, and after swelling, they also covered the exposed side area of the tablet. It seems that swelling and morphological change of CP layers minimize the erosional release for rapidly erodible PEO200K (Mw 200,000) and change the NP release to a diffusion-controlled process. For PEO900K (Mw 900,000), initial release rate was slower than that of PEO200K, possibly due to the slower swelling and erosional release from the side of the tablet. Diffusional release seemed to be the dominating mechanism for the release of NP from PEO7000K (Mw 7,000,000) tablet. Physical mixture of PEO and CP delayed the release of NP remarkably. The increase in pH, ionic strength and buffer concentration of the dissolution medium decreased the release rate. The data obtained for capped and blended tablets were fitted using the power law equation to understand the release mechanism. These results provided some useful information on parameters which can be modulated in the design of a controlled release dosage form for NP.

  15. Assessing post-depositional alteration and the integrity of ice core nitrate-N and -O isotopic records at the Quelccaya Ice Cap, Peru

    NASA Astrophysics Data System (ADS)

    Buffen, A. M.; Hastings, M. G.; Thompson, L. G.; Mosley-Thompson, E. S.

    2011-12-01

    Nitrate (NO3-) is a common chemical species found in snow and ice. Both nitrate and its atmospheric precursor NOx (NO and NO2) are of importance to climate, biogeochemistry and the composition of the atmosphere. For instance, nitrate is a critical biological nutrient, while NOx regulates concentrations of ozone (O3) and hydroxyl (OH) and thus influences the chemical and radiative properties of Earth's atmosphere. NOx sources include fossil fuel combustion, biomass burning, soil microbial processes and lightning. Past changes in NOx emissions, tropospheric distributions and consequent effects on the atmosphere, however, are unknown. Interpreting stable nitrogen (δ15N) and oxygen (δ18O and Δ17O) isotope ratios in nitrate preserved in ice cores can address these issues as they contain diagnostic signatures of NOx sources and oxidation processes, respectively. The potential caveat to this is that nitrate can be lost from snow and firn via photolysis (as NOx) and/or volatilization (as nitric acid). Because these processes are isotopically fractionating, it is necessary to determine if, or to what degree, such post-depositional alteration takes place at a given site before an isotopic record from ice core nitrate can be utilized as a paleoenvironmental proxy. This work addresses post-depositional alteration at the Quelccaya Ice Cap (5670 masl) in southeastern Peru in order to assess the integrity of the nitrate record in an 1800-year ice core from the site. This work represents the first of its kind outside the polar regions and is significant in that natural NOx sources and OH production are dominantly located in the Tropics. Additionally, because nitrate and NOx are not uniformly distributed in the troposphere, low-latitude records are needed to bridge ongoing polar work in order to establish a global perspective.

  16. Multielement determination of cadmium and lead in urine by simultaneous electrothermal atomic absorption spectrometry with an end-capped graphite tube.

    PubMed

    Correia, Paulo R M; Nomura, Cassiana S; Oliveira, Pedro V

    2003-11-01

    A method for the multielement determination of cadmium and lead in urine is proposed by simultaneous electrothermal atomic absorption spectrometry (SIMAAS) with an end-capped transversely heated graphite atomizer (EC-THGA). The best conditions for cadmium and lead determination were obtained in the presence of NH4H2PO4 as a chemical modifier, using 500 degrees C and 1800 degrees C as the pyrolysis and atomization temperatures, respectively. Urine samples were diluted 1 + 4 directly in autosampler cups with a mixture of 0.125% (w/v) Triton X-100 + 2.5% (v/v) HNO3 + 0.31% (w/v) NH4H2PO4. The optimized heating program was carried out in 57 s, and the instrument calibration was done with aqueous reference solutions. The use of EC-THGA increased the sensitivity of cadmium and lead by 14% and 25%, respectively. The detection limits (n = 20, 3delta) were 0.03 microg L(-1) (0.36 pg) for cadmium and 0.57 microg L(-1) (6.8 pg) for lead. The performance of EC-THGA was acceptable up to 500 heating cycles. The reliability of the entire procedure was checked with the analysis of a lyophilized urine certified reference material. The found concentrations were in agreement with the recommended values (95% confidence level).

  17. Engineering of lead chalcogenide nanostructures for carrier multiplication: Core/shell, 1D, and 2D

    NASA Astrophysics Data System (ADS)

    Lin, Qianglu

    Near infrared emitting semiconductors have been used widely in industry especially in solar-cell fabrications. The efficiency of single junction solar-cell can reach the Shockley-Queisser limit by using optimum band gap material such as silicon and cadmium telluride. The theoretical efficiency can be further enhanced through carrier multiplication, in which a high energy photon is absorbed and more than one electron-hole pair can be generated, reaching more than 100% quantum efficiency in the high energy region of sunlight. The realization of more than unity external quantum efficiency in lead selenide quantum dots solar cell has motivated vast investigation on lowering the carrier multiplication threshold and further improving the efficiency. This dissertation focuses on synthesis of lead chalcogenide nanostructures for their optical spectroscopy studies. PbSe/CdSe core/shell quantum dots were synthesized by cation exchange to obtain thick shells (up to 14 monolayers) for studies of visible and near infrared dual band emissions and carrier multiplication efficiency. By examining the reaction mechanism, a thermodynamic and a kinetic model are introduced to explain the vacancy driven cation exchange. As indicated by the effective mass model, PbSe/CdSe core/shell quantum dots has quasi-type-II band alignment, possessing electron delocalized through the entire quantum dot and hole localized in the core, which breaks down the symmetry of energy levels in the conduction and valence band, leading to hot-hole-assisted efficient multi-exciton generation and a lower carrier multiplication threshold to the theoretical value. For further investigation of carrier multiplication study, PbTe, possessing the highest efficiency among lead chalcogenides due to slow intraband cooling, is synthesized in one-dimensional and two-dimensional nanostructures. By using dodecanethiol as the surfactant, PbTe NRs can be prepared with high uniformity in width and resulted in fine quantum

  18. Ice core record of rising lead pollution in the North Pacific atmosphere

    NASA Astrophysics Data System (ADS)

    Osterberg, E.; Mayewski, P.; Kreutz, K.; Fisher, D.; Handley, M.; Sneed, S.; Zdanowicz, C.; Zheng, J.; Demuth, M.; Waskiewicz, M.; Bourgeois, J.

    2008-03-01

    A high-resolution, 8000 year-long ice core record from the Mt. Logan summit plateau (5300 m asl) reveals the initiation of trans-Pacific lead (Pb) pollution by ca. 1730, and a >10-fold increase in Pb concentration (1981-1998 mean = 68.9 ng/l) above natural background (5.6 ng/l) attributed to rising anthropogenic Pb emissions from Asia. The largest rise in North Pacific Pb pollution from 1970-1998 (end of record) is contemporaneous with a decrease in Eurasian and North American Pb pollution as documented in ice core records from Greenland, Devon Island, and the European Alps. The distinct Pb pollution history in the North Pacific is interpreted to result from the later industrialization and less stringent abatement measures in Asia compared to North America and Eurasia. The Mt. Logan record shows evidence for both a rising Pb emissions signal from Asia and a trans-Pacific transport efficiency signal related to the strength of the Aleutian Low.

  19. Core--strategy leading to high reversible hydrogen storage capacity for NaBH4.

    PubMed

    Christian, Meganne L; Aguey-Zinsou, Kondo-François

    2012-09-25

    Owing to its high storage capacity (10.8 mass %), sodium borohydride (NaBH(4)) is a promising hydrogen storage material. However, the temperature for hydrogen release is high (>500 °C), and reversibility of the release is unachievable under reasonable conditions. Herein, we demonstrate the potential of a novel strategy leading to high and stable hydrogen absorption/desorption cycling for NaBH(4) under mild pressure conditions (4 MPa). By an antisolvent precipitation method, the size of NaBH(4) particles was restricted to a few nanometers (<30 nm), resulting in a decrease of the melting point and an initial release of hydrogen at 400 °C. Further encapsulation of these nanoparticles upon reaction of nickel chloride at their surface allowed the synthesis of a core--shell nanostructure, NaBH(4)@Ni, and this provided a route for (a) the effective nanoconfinement of the melted NaBH(4) core and its dehydrogenation products, and (b) reversibility and fast kinetics owing to short diffusion lengths, the unstable nature of nickel borohydride, and possible modification of reaction paths. Hence at 350 °C, a reversible and steady hydrogen capacity of 5 mass % was achieved for NaBH(4)@Ni; 80% of the hydrogen could be desorbed or absorbed in less than 60 min, and full capacity was reached within 5 h. To the best of our knowledge, this is the first time that such performances have been achieved with NaBH(4). This demonstrates the potential of the strategy in leading to major advancements in the design of effective hydrogen storage materials from pristine borohydrides.

  20. Photogenerated carriers transport behaviors in L-cysteine capped ZnSe core-shell quantum dots

    SciTech Connect

    Shan, Qingsong; Li, Kuiying Lin, Yingying; Yin, Hua; Zhu, Ruiping; Xue, Zhenjie

    2016-02-07

    The photoexcited carrier transport behavior of zinc selenide (ZnSe) quantum dots (QDs) with core–shell structure is studied because of their unique photoelectronic characteristics. The surface photovoltaic (SPV) properties of self-assembled ZnSe/ZnS/L-Cys core–shell QDs were probed via electric field induced surface photovoltage and transient photovoltage (TPV) measurements supplemented by Fourier transform infrared, laser Raman, absorption, and photoluminescence spectroscopies. The ZnSe QDs displayed p-type SPV characteristics with a broader stronger SPV response over the whole ultraviolet-to-near-infrared range compared with those of other core–shell QDs in the same group. The relationship between the SPV phase value of the QDs and external bias was revealed in their SPV phase spectrum. The wide transient photovoltage response region from 3.3 × 10{sup −8} to 2 × 10{sup −3} s was closely related to the long diffusion distance of photoexcited free charge carriers in the interfacial space–charge region of the QDs. The strong SPV response corresponding to the ZnSe core mainly originated from an obvious quantum tunneling effect in the QDs.

  1. Studies Conducted of Sodium Carbonate Contaminant Found on the Wing Leading Edge and the Nose Cap of the Space Shuttle Orbiter

    NASA Technical Reports Server (NTRS)

    Jacobson, Nathan S.; Palou, Jaime J.

    2003-01-01

    In early 2001, three of the space shuttle orbiters were found to have a sodium carbonate contaminant on the wing leading edge and nose cap. These parts are made of a reinforced carbon/carbon material protected by silicon carbide (SiC) and a glass coating. The glass coating is known as Type A and is primarily sodium silicate with particles of SiC. NASA Glenn Research Center's Environmental Durability Branch was asked to determine the chemistry of this deposit formation and assess any possible detrimental effects. At low temperatures, the reverse reaction is favorable. Previous studies of the corrosion of glass show that carbon dioxide in the presence of water does form sodium carbonate on sodium silicate glass (ref. 1). It is quite likely that a similar scenario exists for the orbiter wing leading edge. All three orbiters that formed sodium carbonate were exposed to rain. This formation of sodium carbonate was duplicated in the laboratory. The Type A glass, which coats the wing leading edge and nose cap, was made in a freestanding form and exposed to water in two separate experiments. In one set of experiments, the coating was placed in a petri dish filled with water. As the water evaporated, sodium carbonate formed. In another case, water was slowly dripped on the coating and sodium carbonate formed. The sodium carbonate was detected by chemical analysis and, in some cases, xray diffraction showed a hydrated sodium carbonate. The next step was to examine possible detrimental effects of this sodium carbonate. There are three likely scenarios for the sodium carbonate deposit: (1) it may be removed with a simple rinse, (2) it may remain and flow back into the Type A glass after heating during reentry, or (3) it may remain and flow onto unprotected SiC and/or other parts after heating during reentry. The effect of case 1 is to remove the Na2O constituent from the Type A glass, thus decreasing its effectiveness as a sealant. Even so, overall, it is probably the best

  2. Studies Conducted of Sodium Carbonate Contaminant Found on the Wing Leading Edge and the Nose Cap of the Space Shuttle Orbiter

    NASA Technical Reports Server (NTRS)

    Jacobson, Nathan S.; Palou, Jaime J.

    2003-01-01

    In early 2001, three of the space shuttle orbiters were found to have a sodium carbonate contaminant on the wing leading edge and nose cap. These parts are made of a reinforced carbon/carbon material protected by silicon carbide (SiC) and a glass coating. The glass coating is known as Type A and is primarily sodium silicate with particles of SiC. NASA Glenn Research Center's Environmental Durability Branch was asked to determine the chemistry of this deposit formation and assess any possible detrimental effects. At low temperatures, the reverse reaction is favorable. Previous studies of the corrosion of glass show that carbon dioxide in the presence of water does form sodium carbonate on sodium silicate glass (ref. 1). It is quite likely that a similar scenario exists for the orbiter wing leading edge. All three orbiters that formed sodium carbonate were exposed to rain. This formation of sodium carbonate was duplicated in the laboratory. The Type A glass, which coats the wing leading edge and nose cap, was made in a freestanding form and exposed to water in two separate experiments. In one set of experiments, the coating was placed in a petri dish filled with water. As the water evaporated, sodium carbonate formed. In another case, water was slowly dripped on the coating and sodium carbonate formed. The sodium carbonate was detected by chemical analysis and, in some cases, xray diffraction showed a hydrated sodium carbonate. The next step was to examine possible detrimental effects of this sodium carbonate. There are three likely scenarios for the sodium carbonate deposit: (1) it may be removed with a simple rinse, (2) it may remain and flow back into the Type A glass after heating during reentry, or (3) it may remain and flow onto unprotected SiC and/or other parts after heating during reentry. The effect of case 1 is to remove the Na2O constituent from the Type A glass, thus decreasing its effectiveness as a sealant. Even so, overall, it is probably the best

  3. Core-shell structured polypyrrole/mesoporous SiO2 nanocomposite capped with graphene quantum dots as gatekeeper for irradiation-controlled release of methotrexate.

    PubMed

    Liu, Xiaolin; Shou, Dan; Chen, Chuanxiang; Mao, Huihui; Kong, Yong; Tao, Yongxin

    2017-12-01

    A core-shell structured nanocomposite of polypyrrole/mesoporous SiO2 (PPy/mSiO2) is rationally designed as the nanocarrier for methotrexate (MTX), a chemotherapeutic drug for cancer treatment. Graphene quantum dots (GQDs) are introduced to the outer surface of PPy/mSiO2, and it functions as a gatekeeper for the loaded MTX through the formation of H-bonds with the functionalized mSiO2. In the proposed nanocarrier for MTX, the mesopores in mSiO2 are beneficial for the accommodation of MTX, resulting in enhanced encapsulation capacity of the nanocarrier; on the other hand, PPy can effectively convert the near-infrared (NIR) light to heat. Under the irradiation of NIR light, the H-bonds between GQDs and mSiO2 are broken due to the gradually increased temperature, and therefore the GQDs cap is removed and consequently the encapsulated MTX is released from the nanocarrier. In this study, NIR irradiation-controlled drug delivery is achieved successfully owing to the synergistic effects of PPy, mSiO2 and GQDs, which opens a new window for the construction of smart drug delivery systems. Copyright © 2017 Elsevier B.V. All rights reserved.

  4. The effect of varying the capping agent of magnetic/luminescent Fe3O4-InP/ZnSe core-shell nanocomposite

    NASA Astrophysics Data System (ADS)

    Paulsen, Zuraan; Onani, Martin O.; Allard, Garvin R. J.; Kiplagat, Ayabei; Okil, Joseph O.; Dejene, Francis B.; Mahanga, Geoffrey M.

    2016-01-01

    Magnetic-luminescent nanoparticles have shown great promise in various biomedical applications namely: contrast agents for magnetic resonance imaging, multifunctional drug carrier system, magnetic separation of cells, cell tracking, immunoassay, and magnetic bioseparation. This experiment describes the synthesis of a nanocomposite material, which is composed of an iron oxide (Fe3O4) superparamagnetic core and an indium phosphide/zinc selenide (InP/ZnSe) quantum dot shell. The magnetic nanoparticles (MNP's) and quantum dots (QD's) were synthesized separately before allowing them to conjugate. The MNP's were functionalized with a thiol-group allowing the QD shell to bind to the surface of the MNP by the formation of a thiol-metal bond. The nanocomposite was capped with 3-mercaptopropionic acid, oleylamine, β-cyclodextrin and their influence on the photoluminescence investigated. The synthesized nanocomposite was characterized with high- resolution transmission electron microscopy (HR-TEM), energy-dispersive spectroscopy (EDS), selective electron area diffraction (SAED), scanning electron microscopy (SEM), superconducting quantum interference device (SQUID), and photoluminescence. These techniques yielded particle size, morphology, dispersion, and chemical composition including luminescence and florescence.

  5. Analysis of vanillic acid in polar ice cores as a biomass burning proxy - preliminary results from the Akademii Nauk Ice Cap in Siberia

    NASA Astrophysics Data System (ADS)

    Grieman, M. M.; Jimenez, R.; McConnell, J. R.; Fritzsche, D.; Saltzman, E. S.

    2013-12-01

    Biomass burning influences global climate change and the composition of the atmosphere. The drivers, effects, and climate feedbacks related to fire are poorly understood. Many different proxies have been used to reconstruct past fire frequency from lake sediments and polar ice cores. Reconstruction of historical trends in biomass burning is challenging because of regional variability and the qualitative nature of various proxies. Vanillic acid (4-hydroxy-3-methoxybenzoic acid) is a product of the combustion of conifer lignin that is known to occur in biomass burning aerosols. Biomass burning is likely the only significant source of vanillic acid in polar ice. In this study we describe an analytical method for quantifying vanillic acid in polar ice using HPLC with electrospray ionization and tandem mass spectrometric detection. The method has a detection limit of 100 pM and a precision of × 10% at the 100 pM level for analysis of 100 μl of ice melt water. The method was used to analyze more than 1000 discrete samples from the Akademii Nauk ice cap on Severnaya Zemlya in the high Russia Arctic (79°30'N, 97°45'E) (Fritzsche et al., 2002; Fritzsche et al., 2005; Weiler et al., 2005). The samples range in age over the past 2,000 years. The results show a mean vanillic acid concentration of 440 × 710 pM (1σ), with elevated levels during the periods from 300-600 and 1450-1550 C.E.

  6. Statistical survey of pitch angle distributions in core (0-50 eV) ions from Dynamics Explorer 1: Outflow in the auroral zone, polar cap, and cusp

    NASA Technical Reports Server (NTRS)

    Giles, B. L.; Chappell, C. R.; Moore, T. E.; Comfort, R. H.; Waite, J. H., Jr.

    1994-01-01

    Core (0-50 eV) ion pitch angle measurements from the retarding ion mass spectrometer on Dynamics Explorer 1 are examined with respect to magnetic disturbance, invariant latitude, magnetic local time, and altitude for ions H(+), He(+), O(+), M/Z = 2 (D(+) or He(++)), and O(++). Included are outflow events in the auroral zone, polar cap, and cusp, separated into altitude regions below and above 3 R(sub E). In addition to the customary division into beam, conic, and upwelling distributions, the high-latitude observations fall into three categories corresponding to ion bulk speeds that are (1) less than, (2) comparable to, or (3) faster than that of the spacecraft. This separation, along with the altitude partition, serves to identify conditions under which ionospheric source ions are gravita- tionally bound and when they are more energetic and able to escape to the outer magnetosphere. Features of the cleft ion fountain inferred from single event studies are clearly identifiable in the statistical results. In addition, it is found that the dayside pre-noon cleft is a dayside afternoon cleft, or auroral zone, becomes an additional source for increased activity. The auroral oval as a whole appears to be a steady source of escape velocity H(+), a steady source of escape velocity He(+) ions for the dusk sector, and a source of escape velocity heavy ions for dusk local times primarily during increased activity. The polar cap above the auroral zone is a consistent source of low-energy ions, although only the lighter mass particles appear to have sufficient velocity, on average, to escape to higher altitudes. The observations support two concepts for outflow: (1) The cleft ion fountain consists of ionospheric plasma of 1-20 eV energy streaming upward into the magnetosphere where high-latitude convection electric fields cause poleward dispersion. (2) The auroral ion fountain involves field-aligned beams which flow out along auroral latitude field lines; and, in addition, for

  7. Three centuries of Eastern European and Altai lead emissions recorded in a Belukha ice core.

    PubMed

    Eichler, Anja; Tobler, Leonhard; Eyrikh, Stella; Gramlich, Gabriela; Malygina, Natalia; Papina, Tatyana; Schwikowski, Margit

    2012-04-17

    Human activities have significantly altered atmospheric Pb concentrations and thus, its geochemical cycle, for thousands of years. Whereas historical Pb emissions from Western Europe, North America, and Asia are well documented, there is no equivalent data for Eastern Europe. Here, we present ice-core Pb concentrations for the period 1680-1995 from Belukha glacier in the Siberian Altai, assumed to be representative of emissions in Eastern Europe and the Altai. Pb concentrations and (207)Pb/(206)Pb ratios were strongly enhanced during the period 1935-1995 due to the use of Pb additives in Russian gasoline mined in the Rudny Altai. Comparable to Western Europe and North America, Eastern European Pb emissions peaked in the 1970s. However, the subsequent downward trend in Eastern Europe was mainly caused by the economic crisis in the U.S.S.R. and not by a phase-out of leaded gasoline. Pb concentrations in the period 1680-1935, preceding the era of intensified industrialization in Russia, reflect the history of local emissions from Rudny Altai mining and related metallurgical processing primarily for the production of Russian coins. During this time, Altai ore Pb contributed about 40% of the regional atmospheric Pb.

  8. Embrittlement phenomenon of Ag core MP35N cable as lead conductor in medical device.

    PubMed

    Wang, Ling; Li, Bernie; Zhang, Haitao

    2013-02-01

    Ag core MP35N (Ag/MP35N) wire has been used in lead electric conductor wires in the medical device industry for many years. Recently it was noticed that the combination of silver and MP35N restricts its wire drawing process. The annealing temperature in Ag/MP35N has to be lower than the melting temperature of pure Ag (960 °C), which cannot fully anneal MP35N. The lower annealing temperature results in a highly cold worked MP35N, which significantly reduces Ag/MP35N ductility. The embrittlement phenomenon of Ag/MP35N cable was observed in tension and bending deformation. The effect of the embrittlement on the wire flex fatigue life was evaluated using a newly developed flex fatigue testing method. The Ag/MP35N cable fatigue results was analyzed with a Coffin-Manson approach and compared to the MP35N cable fatigue results. The root causes of the Ag/Mp35N embrittlement phenomenon are discussed.

  9. Lead

    MedlinePlus

    ... EPA United States Environmental Protection Agency Search Search Lead Contact Us Share Lead Poisoning is Preventable If your home was built ... to protect people from harmful lead exposures. Less Lead in Drinking Water = Better Health Learn about the ...

  10. Residual Cap

    NASA Image and Video Library

    2006-05-10

    This MOC image shows a summertime view of the south polar residual cap of Mars. In this image, mesas composed largely of solid carbon dioxide are separated from one another by irregularly-shaped depressions

  11. Cradle Cap

    MedlinePlus

    ... and hair follicles. Another factor may be a yeast (fungus) called malassezia (mal-uh-SEE-zhuh) that ... ketoconazole, are often effective, supporting the idea that yeast is a contributing factor. Cradle cap isn't ...

  12. Cervical Cap

    MedlinePlus

    ... Staff The cervical cap is a birth control (contraceptive) device that prevents sperm from entering the uterus. ... more times a week, you've had previous contraceptive failure with vaginal barrier methods or you're ...

  13. Cusp Cap

    NASA Astrophysics Data System (ADS)

    Murdin, P.

    2000-11-01

    A brightening at one or other of the tips—cusps—of the crescent phase of Venus, as seen from Earth. Cusp caps were first reported by the German amateur astronomer Baron Franz Paula von Gruithuisen in 1813, and have been recorded by telescopic observers ever since. They were named by analogy with the Earth's polar caps; early observers fancied they were seeing glimpses of a possibly Earth-like sur...

  14. Cradle Cap (For Parents)

    MedlinePlus

    ... Kids to Be Smart About Social Media Cradle Cap (Infantile Seborrheic Dermatitis) KidsHealth > For Parents > Cradle Cap ( ... many babies develop called cradle cap. About Cradle Cap Cradle cap is the common term for seborrheic ...

  15. Polar Cap Patch Dynamics

    DTIC Science & Technology

    2013-04-25

    illustrate the concept with a sample model -run incorporating representative data. Title 12: Space weather challenges of the polar cap ionosphere ...located at Oslo and Ny-Ålesund. The primary objective has been to obtain a better understanding solar wind impacts on the polar ionosphere which are of...made no inventions, and Section 8 lists the core UiO personnel during this project. 15. SUBJECT TERMS EOARD, ionosphere (polar

  16. Ultrasensitive and rapid lead sensing in water based on environmental friendly and high luminescent L-glutathione-capped-ZnSe quantum dots.

    PubMed

    Cai, Zhaoxia; Shi, Baoqin; Zhao, Lei; Ma, Meihu

    2012-11-01

    Water-soluble and high luminescent l-glutathione-capped-ZnSe quantum dots (QDs) were applied for ultrasensitive Pb(II) detection. l-glutathione-capped-ZnSe QDs were synthesized by a facile colloid aqueous phase route. It is characterized by transmission electron microscopy, X-ray powder diffraction spectrometry, Fourier transform infrared spectrometry, Ultraviolet-visible spectrometry and fluorescence spectrometry. Quantum yields of l-glutathione-capped-ZnSe QDs could reach 50.1% without post irradiation. The fluorescence quenching of the l-glutathione-capped-ZnSe QDs depended on the concentration, pH and reaction time of the Pb(II) solution. The possible mechanism of fluorescence of l-glutathione-capped-ZnSe QDs quenched by Pb(II) was discussed in detail. Under optimal conditions, the quenched fluorescence intensity increased linearly with the concentration of Pb(II) in the range of 1.0×10(-8)∼8.0×10(-7)mol/L. The limit of detection for Pb(II) was 0.71 nmol/L. This developed method is demonstrated to contain improved sensitive and selective characteristics for the detection of trace Pb(II) in water. Crown Copyright © 2012. Published by Elsevier B.V. All rights reserved.

  17. Facile synthesis of mercaptosuccinic acid-capped CdTe/CdS/ZnS core/double shell quantum dots with improved cell viability on different cancer cells and normal cells

    NASA Astrophysics Data System (ADS)

    Parani, Sundararajan; Bupesh, Giridharan; Manikandan, Elayaperumal; Pandian, Kannaiyan; Oluwafemi, Oluwatobi Samuel

    2016-11-01

    Water-soluble, mercaptosuccinic acid (MSA)-capped CdTe/CdS/ZnS core/double shell quantum dots (QDs) were prepared by successive growth of CdS and ZnS shells on the as-synthesized CdTe/CdSthin core/shell quantum dots. The formation of core/double shell structured QDs was investigated by ultraviolet-visible (UV-Vis) absorption and photoluminescence (PL) spectroscopy, PL decay studies, X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The core/double shell QDs exhibited good photoluminescence quantum yield (PLQY) which is 70% higher than that of the parent core/shell QDs, and they are stable for months. The average particle size of the core/double shell QDs was ˜3 nm as calculated from the transmission electron microscope (TEM) images. The cytotoxicity of the QDs was evaluated on a variety of cancer cells such as HeLa, MCF-7, A549, and normal Vero cells by 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) cell viability assay. The results showed that core/double shell QDs were less toxic to the cells when compared to the parent core/shell QDs. MCF-7 cells showed proliferation on incubation with QDs, and this is attributed to the metalloestrogenic activity of cadmium ions released from QDs. The core/double shell CdTe/CdS/ZnS (CSS) QDs were conjugated with transferrin and successfully employed for the biolabeling and fluorescent imaging of HeLa cells. These core/double shell QDs are highly promising fluorescent probe for cancer cell labeling and imaging applications.

  18. Tracking historical mobility behavior and sources of lead in the 59-year sediment core from the Huaihe River using lead isotopic compositions.

    PubMed

    Wang, Jie; Liu, Guijian; Liu, Houqi; Lam, Paul K S

    2017-10-01

    A historical perspective of past 59 years (1955-2014) for contamination and isotopic composition of Pb in sediment core system of the Huaihe River, Huainan City, Anhui Province of China is presented. Detailed investigation regarding changes in Pb sources, enrichment factor, sequential extraction and isotopic analysis revealed that high Pb concentrations were detected along the core, especially during the first two decades (1955-1974). Large variations in Pb isotopic compositions were observed, with (206)Pb/(207)Pb and (208)Pb/(207)Pb values ranging from 1.1504-1.1694, and 2.0817-2.1380, respectively. Diverse Pb sources were identified for sediment contamination over the time. Among anthropogenic sources, metallurgic dust and leaded petrol were on top during 1955-1974, especially when the Great Leap Forward Movement (1958-1960) was in progress in China, the time numerous small industries were established without wastewater treatment facility. However, coal and coal combustion were recognized as the primary sources of Pb emissions for the recent four decades (1974-2014) due to tremendous increase of coal consumption for power and heat generation. Unleaded vehicle exhaust, waste incineration and industrial emission were also sources of Pb during the years 1974-2014. Our estimates based on geochemical and lead isotopic approaches have shown that anthropogenic Pb contributions varied from 4.35 to 92.01%, and 13.28-99.06%, respectively. Assessment of lead speciation indicated an overwhelming presence of reducible fraction (Fe-Mn hydro-(oxides)) in the sediment core, except during 1995-1997, which was thought to be affected by water pollution accidents caused by heavy rainfall. Copyright © 2017 Elsevier Ltd. All rights reserved.

  19. Designing, Leading and Managing the Transition to the Common Core: A Strategy Guidebook for Leaders

    ERIC Educational Resources Information Center

    Brown, Brentt; Vargo, Merrill

    2014-01-01

    The Common Core provides districts an opportunity to renew their focus on teaching and learning. But it also poses a number of design and implementation challenges for school districts. The "Leadership and Design Cycles" described in this guidebook offers an evidenced-based and structured process for leaders to design and implement…

  20. Leading the Common Core State Standards: From Common Sense to Common Practice

    ERIC Educational Resources Information Center

    Dunkle, Cheryl A.

    2012-01-01

    Many educators agree that we already know how to foster student success, so what is keeping common sense from becoming common practice? The author provides step-by-step guidance for overcoming the barriers to adopting the Common Core State Standards (CCSS) and achieving equity and excellence for all students. As an experienced teacher and…

  1. Analysis of C/E results of fission rate ratio measurements in several fast lead VENUS-F cores

    NASA Astrophysics Data System (ADS)

    Kochetkov, Anatoly; Krása, Antonín; Baeten, Peter; Vittiglio, Guido; Wagemans, Jan; Bécares, Vicente; Bianchini, Giancarlo; Fabrizio, Valentina; Carta, Mario; Firpo, Gabriele; Fridman, Emil; Sarotto, Massimo

    2017-09-01

    During the GUINEVERE FP6 European project (2006-2011), the zero-power VENUS water-moderated reactor was modified into VENUS-F, a mock-up of a lead cooled fast spectrum system with solid components that can be operated in both critical and subcritical mode. The Fast Reactor Experiments for hybrid Applications (FREYA) FP7 project was launched in 2011 to support the designs of the MYRRHA Accelerator Driven System (ADS) and the ALFRED Lead Fast Reactor (LFR). Three VENUS-F critical core configurations, simulating the complex MYRRHA core design and one configuration devoted to the LFR ALFRED core conditions were investigated in 2015. The MYRRHA related cores simulated step by step design peculiarities like the BeO reflector and in pile sections. For all of these cores the fuel assemblies were of a simple design consisting of 30% enriched metallic uranium, lead rodlets to simulate the coolant and Al2O3 rodlets to simulate the oxide fuel. Fission rate ratios of minor actinides such as Np-237, Am-241 as well as Pu-239, Pu-240, Pu-242 and U-238 to U-235 were measured in these VENUS-F critical assemblies with small fission chambers in specially designed locations, to determine the spectral indices in the different neutron spectrum conditions. The measurements have been analyzed using advanced computational tools including deterministic and stochastic codes and different nuclear data sets like JEFF-3.1, JEFF-3.2, ENDF/B7.1 and JENDL-4.0. The analysis of the C/E discrepancies will help to improve the nuclear data in the specific energy region of fast neutron reactor spectra.

  2. Lead

    MedlinePlus

    ... are approximately half a million U.S. children ages 1-5 with blood lead levels above 5 micrograms per deciliter (µg/dL), the reference level at which CDC recommends public health actions be initiated. No safe blood lead level in children has been ...

  3. Cradle cap

    MedlinePlus

    ... known. Doctors think the condition is due to oil glands in the baby's scalp producing too much oil. Cradle cap is not spread from person to ... each day to remove any scales and scalp oil. If scales do not easily loosen and wash ...

  4. Failure of a Neutrino-driven Explosion after Core-collapse May Lead to a Thermonuclear Supernova

    NASA Astrophysics Data System (ADS)

    Kushnir, Doron; Katz, Boaz

    2015-10-01

    We demonstrate that ∼10 s after the core-collapse of a massive star, a thermonuclear explosion of the outer shells is possible for some (tuned) initial density and composition profiles, assuming that the neutrinos failed to explode the star. The explosion may lead to a successful supernova, as first suggested by Burbidge et al. We perform a series of one-dimensional (1D) calculations of collapsing massive stars with simplified initial density profiles (similar to the results of stellar evolution calculations) and various compositions (not similar to 1D stellar evolution calculations). We assume that the neutrinos escaped with a negligible effect on the outer layers, which inevitably collapse. As the shells collapse, they compress and heat up adiabatically, enhancing the rate of thermonuclear burning. In some cases, where significant shells of mixed helium and oxygen are present with pre-collapsed burning times of ≲100 s (≈10 times the free-fall time), a thermonuclear detonation wave is ignited, which unbinds the outer layers of the star, leading to a supernova. The energy released is small, ≲1050 erg, and negligible amounts of synthesized material (including 56Ni) are ejected, implying that these 1D simulations are unlikely to represent typical core-collapse supernovae. However, they do serve as a proof of concept that the core-collapse-induced thermonuclear explosions are possible, and more realistic two-dimensional and three-dimensional simulations are within current computational capabilities.

  5. FAILURE OF A NEUTRINO-DRIVEN EXPLOSION AFTER CORE-COLLAPSE MAY LEAD TO A THERMONUCLEAR SUPERNOVA

    SciTech Connect

    Kushnir, Doron; Katz, Boaz

    2015-10-01

    We demonstrate that ∼10 s after the core-collapse of a massive star, a thermonuclear explosion of the outer shells is possible for some (tuned) initial density and composition profiles, assuming that the neutrinos failed to explode the star. The explosion may lead to a successful supernova, as first suggested by Burbidge et al. We perform a series of one-dimensional (1D) calculations of collapsing massive stars with simplified initial density profiles (similar to the results of stellar evolution calculations) and various compositions (not similar to 1D stellar evolution calculations). We assume that the neutrinos escaped with a negligible effect on the outer layers, which inevitably collapse. As the shells collapse, they compress and heat up adiabatically, enhancing the rate of thermonuclear burning. In some cases, where significant shells of mixed helium and oxygen are present with pre-collapsed burning times of ≲100 s (≈10 times the free-fall time), a thermonuclear detonation wave is ignited, which unbinds the outer layers of the star, leading to a supernova. The energy released is small, ≲10{sup 50} erg, and negligible amounts of synthesized material (including {sup 56}Ni) are ejected, implying that these 1D simulations are unlikely to represent typical core-collapse supernovae. However, they do serve as a proof of concept that the core-collapse-induced thermonuclear explosions are possible, and more realistic two-dimensional and three-dimensional simulations are within current computational capabilities.

  6. Apical cap

    SciTech Connect

    McLoud, T.C.; Isler, R.J.; Novelline, R.A.; Putman, C.E.; Simeone, J.; Stark, P.

    1981-08-01

    Apical caps, either unilateral or bilateral, are a common feature of advancing age and are usually the result of subpleural scarring unassociated with other diseases. Pancoast (superior sulcus) tumors are a well recognized cause of unilateral asymmetric apical density. Other lesions arising in the lung, pleura, or extrapleural space may produce unilateral or bilateral apical caps. These include: (1) inflammatory: tuberculosis and extrapleural abscesses extending from the neck; (2) post radiation fibrosis after mantle therapy for Hodgkin disease or supraclavicular radiation in the treatment of breast carcinoma; (3) neoplasm: lymphoma extending from the neck or mediastinum, superior sulcus bronchogenic carcinoma, and metastases; (4) traumatic: extrapleural dissection of blood from a ruptured aorta, fractures of the ribs or spine, or hemorrhage due to subclavian line placement; (5) vascular: coarctation of the aorta with dilated collaterals over the apex, fistula between the subclavian artery and vein; and (6) miscellaneous: mediastinal lipomatosis with subcostal fat extending over the apices.

  7. A simple and facile synthesis of MPA capped CdSe and CdSe/CdS core/shell nanoparticles

    SciTech Connect

    Sukanya, D.; Sagayaraj, P.

    2015-06-24

    II-VI semiconductor nanostructures, in particular, CdSe quantum dots have drawn a lot of attention because of their promising potential applications in biological tagging, photovoltaic, display devices etc. due to their excellent optical properties, high emission quantum yield, size dependent emission wavelength and high photostability. In this paper, we describe the synthesis and properties of mercaptopropionic acid capped CdSe and CdSe/CdS nanoparticles through a simple and efficient co-precipitation method followed by hydrothermal treatment. The growth process, characterization and the optical absorption as a function of wavelength for the synthesized MPA capped CdSe and CdSe/CdS nanoparticles have been determined using X-ray diffraction study (XRD), Ultraviolet-Visible spectroscopy (UV-Vis), Fourier transform infrared spectroscopy (FT-IR) and High Resolution Transmission Electron Microscopy (HRTEM)

  8. A simple and facile synthesis of MPA capped CdSe and CdSe/CdS core/shell nanoparticles

    NASA Astrophysics Data System (ADS)

    Sukanya, D.; Sagayaraj, P.

    2015-06-01

    II-VI semiconductor nanostructures, in particular, CdSe quantum dots have drawn a lot of attention because of their promising potential applications in biological tagging, photovoltaic, display devices etc. due to their excellent optical properties, high emission quantum yield, size dependent emission wavelength and high photostability. In this paper, we describe the synthesis and properties of mercaptopropionic acid capped CdSe and CdSe/CdS nanoparticles through a simple and efficient co-precipitation method followed by hydrothermal treatment. The growth process, characterization and the optical absorption as a function of wavelength for the synthesized MPA capped CdSe and CdSe/CdS nanoparticles have been determined using X-ray diffraction study (XRD), Ultraviolet-Visible spectroscopy (UV-Vis), Fourier transform infrared spectroscopy (FT-IR) and High Resolution Transmission Electron Microscopy (HRTEM).

  9. Bubble nucleation and migration in a lead-iron hydr(oxide) core-shell nanoparticle

    DOE PAGES

    Niu, Kaiyang; Frolov, Timofey; Xin, Huolin L.; ...

    2015-10-05

    Iron hydroxide is found in a wide range of contexts ranging from biominerals to steel corrosion, and it can transform to anhydrous oxide via releasing O2 gas and H2O. However, it is not well understood how gases transport through a crystal lattice. Here, we present in situ observation of the nucleation and migration of gas bubbles in iron (hydr)oxide using transmission electron microscopy. We create Pb–FeOOH model core–shell nanoparticles in a liquid cell. Under electron irradiation, iron hydroxide transforms to iron oxide, during which bubbles are generated, and they migrate through the shell to the nanoparticle surface. Geometric phase analysismore » of the shell lattice shows an inhomogeneous stain field at the bubbles. In conclusion, our modeling suggests that the elastic interaction between the core and the bubble provides a driving force for bubble migration.« less

  10. Bubble nucleation and migration in a lead-iron hydr(oxide) core-shell nanoparticle

    SciTech Connect

    Niu, Kaiyang; Frolov, Timofey; Xin, Huolin L.; Wang, Junling; Asta, Mark; Zheng, Haimei

    2015-10-05

    Iron hydroxide is found in a wide range of contexts ranging from biominerals to steel corrosion, and it can transform to anhydrous oxide via releasing O2 gas and H2O. However, it is not well understood how gases transport through a crystal lattice. Here, we present in situ observation of the nucleation and migration of gas bubbles in iron (hydr)oxide using transmission electron microscopy. We create Pb–FeOOH model core–shell nanoparticles in a liquid cell. Under electron irradiation, iron hydroxide transforms to iron oxide, during which bubbles are generated, and they migrate through the shell to the nanoparticle surface. Geometric phase analysis of the shell lattice shows an inhomogeneous stain field at the bubbles. In conclusion, our modeling suggests that the elastic interaction between the core and the bubble provides a driving force for bubble migration.

  11. Mercaptoethanol capped CdSe quantum dots and CdSe/ZnS core/shell: synthesis, characterization and cytotoxicity evaluation.

    PubMed

    Painuly, Diksha; Bhatt, Anugya; Krishnan, V Kalliyana

    2013-02-01

    CdSe Quantum dots (Q-dots) and CdSe/ZnS core/shell have been synthesized by wet chemical route using mercaptoethanol (ME) as cappant. The synthesized Q-dots and core/shell were characterized using X-ray diffraction (XRD), Transmission electron microscopy (TEM), Energy dispersive X-ray analysis (EDS), Dynamic Light Scattering (DLS), Optical absorption and luminescence spectroscopy. The core/shell formation was confirmed by both XRD and TEM analysis. The luminescence was shown to be considerably enhanced in the core/shell sample. Effect of dialysis process on the optical properties of the Q-dots and core/shell has also been discussed. Cytotoxicity studies have been carried out for Q-dots and core/shell. CdSe/ZnS core/shell was found to be non-cytotoxic as compared to CdSe Q-dots up to a certain concentration range. Polyethylene glycol (PEG) coating enhances the non-cytotoxic nature of CdSe/ZnS core/shell when compared with bare core/shell.

  12. Novel electrochemical biosensor based on PVP capped CoFe2O4@CdSe core-shell nanoparticles modified electrode for ultra-trace level determination of rifampicin by square wave adsorptive stripping voltammetry.

    PubMed

    Asadpour-Zeynali, Karim; Mollarasouli, Fariba

    2017-06-15

    This work introduces a new electrochemical sensor based on polyvinyl pyrrolidone capped CoFe2O4@CdSe core-shell modified electrode for a rapid detection and highly sensitive determination of rifampicin (RIF) by square wave adsorptive stripping voltammetry. The new PVP capped CoFe2O4@CdSe with core-shell nanostructure was synthesized by a facile synthesis method for the first time. PVP can act as a capping and etching agent for protection of the outer surface nanoparticles and formation of a mesoporous shell, respectively. Another important feature of this work is the choice of the ligand (1,10-phenanthroline) for precursor cadmium complex that works as a chelating agent in order to increase optical and electrical properties and stability of prepared nanomaterial. The nanoparticles have been characterized by field emission scanning electron microscopy (FESEM), transmission electron microscope (TEM), energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), UV-vis, photoluminescence (PL) spectroscopy, FT-IR, and cyclic voltammetry techniques. The PL spectroscopy study of CoFe2O4@CdSe has shown significant PL quenching by the formation of CoFe2O4 core inside CdSe, this shows that CoFe2O4 NPs are efficient electron acceptors with the CdSe. It is clearly observed that the biosensor can significantly enhance electrocatalytic activity towards the oxidation of RIF, under the optimal conditions. The novelty of this work arises from the new synthesis method for the core-shell of CoFe2O4@CdSe. Then, the novel electrochemical biosensor was fabricated for ultra-trace level determination of rifampicin with very low detection limit (4.55×10(-17)M) and a wide linear range from 1.0×10(-16) to 1.0×10(-7)M. The fabricated biosensor showed high sensitivity and selectivity, good reproducibility and stability. Therefore, it was successfully applied for the determination of ultra-trace RIF amounts in biological and pharmaceutical samples with satisfactory recovery data

  13. Mammalian CAP interacts with CAP, CAP2, and actin.

    PubMed

    Hubberstey, A; Yu, G; Loewith, R; Lakusta, C; Young, D

    1996-06-01

    We previously identified human CAP, a homolog of the yeast adenylyl cyclase-associated protein. Previous studies suggest that the N-terminal and C-terminal domains of CAP have distinct functions. We have explored the interactions of human CAP with various proteins. First, by performing yeast two-hybrid screens, we have identified peptides from several proteins that interact with the C-terminal and/or the N-terminal domains of human CAP. These peptides include regions derived from CAP and BAT3, a protein with unknown function. We have further shown that MBP fusions with these peptides can associate in vitro with the N-terminal or C-terminal domains of CAP fused to GST. Our observations indicate that CAP contains regions in both the N-terminal and C-terminal domains that are capable of interacting with each other or with themselves. Furthermore, we found that myc-epitope-tagged CAP coimmunoprecipitates with HA-epitope-tagged CAP from either yeast or mammalian cell extracts. Similar results demonstrate that human CAP can also interact with human CAP2. We also show that human CAP interacts with actin, both by the yeast two-hybrid test and by coimmunoprecipitation of epitope-tagged CAP from yeast or mammalian cell extracts. This interaction requires the C-terminal domain of CAP, but not the N-terminal domain. Thus CAP appears to be capable of interacting in vivo with other CAP molecules, CAP2, and actin. We also show that actin co-immunoprecipitates with HA-CAP2 from mammalian cell extracts.

  14. Waning Cap

    NASA Technical Reports Server (NTRS)

    2006-01-01

    14 June 2006 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows the outer edge of the south polar residual cap of Mars. During summer, the scarps that delineate the sides of the mesas, retreat (on average) by about 3 meters (10 feet) owing to the sublimation of solid carbon dioxide.

    Location near: 85.6oS, 349.8oW Image width: 3 km (1.9 mi) Illumination from: upper left Season: Southern Summer

  15. Waning Cap

    NASA Technical Reports Server (NTRS)

    2006-01-01

    14 June 2006 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows the outer edge of the south polar residual cap of Mars. During summer, the scarps that delineate the sides of the mesas, retreat (on average) by about 3 meters (10 feet) owing to the sublimation of solid carbon dioxide.

    Location near: 85.6oS, 349.8oW Image width: 3 km (1.9 mi) Illumination from: upper left Season: Southern Summer

  16. Lead isotope ratios in six lake sediment cores from Japan Archipelago: Historical record of trans-boundary pollution sources.

    PubMed

    Hosono, Takahiro; Alvarez, Kelly; Kuwae, Michinobu

    2016-07-15

    Sediment cores from six lakes situated from north to south on the Japanese Archipelago were collected during 2009-2010 to investigate the hypothesis that deposition of lead (Pb) was coming from East Asia (including China, South Korea and eastern part of Russia). Accumulation rates and ages of the lake sediment were estimated by the (210)Pb constant rate of supply model and (137)Cs inputs to reconstruct the historical trends of Pb accumulation. Cores from four lakes located in the north and central Japan, showed clear evidence of Pb pollution with a change in the (206)Pb/(207)Pb and (208)Pb/(207)Pb ratios in the recent sediment as compared to the deeper sediment. Among the six studied lakes, significant inputs of anthropogenic lead emissions were observed at Lake Mikazuki (north Hokkaido in north Japan), Lake Chokai (north of Honshu), and Lake Mikuriga (central part of Honshu). Pb isotopic comparison of collected core sediment and previously reported data for wet precipitation and aerosols from different Asian regions indicate that, before 1900, Pb accumulated in these three lakes was not affected by trans-boundary sources. Lake Mikazuki started to receive Pb emissions from Russia in early 1900s, and during the last two decades, this lake has been affected by trans-boundary Pb pollution from northern China. Lake Chokai has received Pb pollutant from northern China since early 1900s until 2009, whereas for the Lake Mikuriga the major Pb contaminant was transported from southern China during the past 100years. The results of our study demonstrate that Japan Archipelago has received trans-boundary Pb emissions from different parts of East Asian region depending on location, and the major source region has changed historically. Copyright © 2016 Elsevier B.V. All rights reserved.

  17. Residual Cap

    NASA Technical Reports Server (NTRS)

    2006-01-01

    10 May 2006 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a summertime view of the south polar residual cap of Mars. In this image, mesas composed largely of solid carbon dioxide are separated from one another by irregularly-shaped depressions. The variation in brightness across this scene is a function of several factors including, but not limited to, varying proportions of dust and solid carbon dioxide, undulating topography, and differences in the roughness of the slopes versus the flat surfaces.

    Location near: 86.7oS, 343.3oW Image width: 3 km (1.9 mi) Illumination from: upper left Season: Southern Summer

  18. Macromolecular Systems with MSA-Capped CdTe and CdTe/ZnS Core/Shell Quantum Dots as Superselective and Ultrasensitive Optical Sensors for Picric Acid Explosive.

    PubMed

    Dutta, Priyanka; Saikia, Dilip; Adhikary, Nirab Chandra; Sarma, Neelotpal Sen

    2015-11-11

    This work reports the development of highly fluorescent materials for the selective and efficient detection of picric acid explosive in the nanomolar range by fluorescence quenching phenomenon. Poly(vinyl alcohol) grafted polyaniline (PPA) and its nanocomposites with 2-mercaptosuccinic acid (MSA)-capped CdTe quantum dots (PPA-Q) and with MSA-capped CdTe/ZnS core/shell quantum dots (PPA-CSQ) are synthesized in a single step free radical polymerization reaction. The thermal stability and photo stability of the polymer increases in the order of PPA < PPA-Q < PPA-CSQ. The polymers show remarkably high selectivity and efficient sensitivity toward picric acid, and the quenching efficiency for PPA-CSQ reaches up to 99%. The detection limits of PPA, PPA-Q, and PPA-CSQ for picric acid are found to be 23, 1.6, and 0.65 nM, respectively, which are remarkably low. The mechanism operating in the quenching phenomenon is proposed to be a combination of a strong inner filter effect and ground state electrostatic interaction between the polymers and picric acid. A portable and cost-effective electronic device for the visual detection of picric acid by the sensory system is successfully fabricated. The device is further employed for quantitative detection of picric acid in real water samples.

  19. Structure and optical properties of new lead(II) coordination polymers and PbO nanoparticles core of polymer

    NASA Astrophysics Data System (ADS)

    Amini, Mostafa M.; Najafi, Ezzatollah; Dehghani, Ali; Ng, Seik Weng

    2015-03-01

    Two lead(II) coordination polymers, [Pb2(4,4‧-bipy)(NO3)4]n (1) and [Pb4(4,4‧-bipy)2(NO3)8(PhN2O2)2]n (2), were synthesized by reaction of lead(II) nitrate with the 4,4‧-bipyridine (4,4‧-bipy) and cupferron ([PhN(O)NO]NH4) ligands and characterized by 1H and 13C NMR, IR, and UV spectroscopies and elemental analysis. The molecular structure of 2 was determined by single-crystal X-ray diffraction. Photoluminescence studies of complexes showed that a good correlation exists between the structures of complexes and emission wavelengths. Utilization of cupferron ligand as a second ligand in the structure of 2 resulted in a red-shift in the both absorption and fluorescence spectra and moderately enhanced the photoluminescence intensity. Lead(II) oxide core that resulted from direct thermal decomposition of complex 2 at 600 °C in air was characterized by X-ray powder diffraction and scanning electron microscopy. The photoluminescence emission spectrum of PbO nanoparticles revealed a strong blue emission band centered at 472 nm, which might be associated with oxygen vacancies.

  20. Reduced Biosynthesis of Digalactosyldiacylglycerol, a Major Chloroplast Membrane Lipid, Leads to Oxylipin Overproduction and Phloem Cap Lignification in Arabidopsis[OPEN

    PubMed Central

    Chen, Lih-Jen; Herrfurth, Cornelia

    2016-01-01

    DIGALACTOSYLDIACYLGLYCEROL SYNTHASE1 (DGD1) is a chloroplast outer membrane protein responsible for the biosynthesis of the lipid digalactosyldiacylglycerol (DGDG) from monogalactosyldiacylglycerol (MGDG). The Arabidopsis thaliana dgd1 mutants have a greater than 90% reduction in DGDG content, reduced photosynthesis, and altered chloroplast morphology. However, the most pronounced visible phenotype is the extremely short inflorescence stem, but how deficient DGDG biosynthesis causes this phenotype is unclear. We found that, in dgd1 mutants, phloem cap cells were lignified and jasmonic acid (JA)-responsive genes were highly upregulated under normal growth conditions. The coronative insensitive1 dgd1 and allene oxide synthase dgd1 double mutants no longer exhibited the short inflorescence stem and lignification phenotypes but still had the same lipid profile and reduced photosynthesis as dgd1 single mutants. Hormone and lipidomics analyses showed higher levels of JA, JA-isoleucine, 12-oxo-phytodienoic acid, and arabidopsides in dgd1 mutants. Transcript and protein level analyses further suggest that JA biosynthesis in dgd1 is initially activated through the increased expression of genes encoding 13-lipoxygenases (LOXs) and phospholipase A-Iγ3 (At1g51440), a plastid lipase with a high substrate preference for MGDG, and is sustained by further increases in LOX and allene oxide cyclase mRNA and protein levels. Our results demonstrate a link between the biosynthesis of DGDG and JA. PMID:26721860

  1. Two Millennia of Pb Pollution Related to Altiplano Metallurgical Activities and Leaded Gasoline in South America from Illimani Ice Core

    NASA Astrophysics Data System (ADS)

    Eichler, A.; Gramlich, G.; Kellerhals, T.; Tobler, L.; Schwikowski, M.

    2014-12-01

    The exploitation of the extended polymetallic deposits of the Altiplano in South America led to significant emissions of the neurotoxic Pb into the atmosphere already since pre-Colonial times. Long-term histories of Pb pollution in Eastern and Western Europe, Asia, and North America suggest that within the Northern Hemisphere emissions from metallurgy and coal combustion are minor compared to that from leaded gasoline during the second half of the 20th century. However, there is no equivalent data for Southern America. Here we present the first comprehensive, high-resolution two millennia Pb emission history for South America, based on an ice core record from Illimani glacier in Bolivia. Illimani is the highest mountain of the eastern Bolivian Andes and is located at the northeastern margin of the Bolivian Altiplano. The 2000 year ice-core based decadal Pb deposition history revealed highest Pb Enrichment Factors (EFs) during the period 1965-85. Metallurgical processing for silver production during periods of the Tiwanaku culture (400-900 AD), the Inca empire (1450-1532 AD), colonial times (1532-1900 AD), and the tin production at the beginning of the 20th century were identified as major sources for enhanced Pb EFs before the 1960s. Gasoline related Pb emissions in 1965-85, however, led to a threefold increase of the Pb EFs compared to the emission level from metal production, considerably preceding those of the past 2000 years. This finding is complementary to the local air pollution signal preserved in lake sediments and in good agreement with various studies from the Northern Hemisphere.

  2. Historical lead isotope record of a sediment core from the Derwent River (Tasmania, Australia): a multiple source environment.

    PubMed

    Townsend, Ashley T; Seen, Andrew J

    2012-05-01

    A 105 cm sediment core from the Derwent River (Tasmania, Australia) was collected in 2004 and was characterised considering both physical (loss on ignition at 550 °C and grain size) and chemical (Fe, Cu, Zn, Cd and Pb concentrations, Pb isotope ratios and (210)Pb dating) properties. The core was analysed to (i) investigate the historical profiles of some important elements associated with the Risdon zinc refinery adjacent to the Derwent River, (ii) determine Pb isotopic signatures of sediment samples, and (iii) assess the veracity of Pb isotope ratios as indicators of contaminant Pb input. Extractable metal concentrations were (all values as mgkg(-1), non-normalised for grain size) Fe: 20,000-35,000, Zn: 42-4500, Pb: 5-1090, Cu: 13-141, and Cd: 1-31; with a close correlation between Cu, Zn, Cd and Pb. Metal enrichment factors (normalised to Al) were Pb: 0.9-144, Zn: 0.8-93, Cd: 0.8-30, Cu: 0.8-8.9 and Fe: 0.9-1.3, confirming anthropogenic contributions of Cu, Zn, Pb and Cd to the sediments. The onset of metal contamination above background levels occurred at a depth between 43 and 49 cm, with maximum concentrations noted near 20 cm for Cu, Zn, Cd and Pb. Lead isotope ratios were determined in sediments using sector field ICP-MS, and were found to be 36.5-38.8, 16.5-18.7 and 1.07-1.20 for (208)Pb/(204)Pb, (206)Pb/(204)Pb and (206)Pb/(207)Pb ratios, respectively. Major Australian ores processed at the refinery over the previous ~90 years include those from Broken Hill, Rosebery, Mt Isa, Elura, Hellyer and Century deposits. Anthropogenic impact by Pb with Broken Hill type isotopic ratio was initially evident in the core at 43-49 cm. The introduction of Rosebery and Elura ores to the refinery was also clearly noted. Pb isotope ratios further highlight that the Derwent River has been exposed to a greater impact by anthropogenic Pb in comparison to other major Tasmanian rivers, namely the Huon and Tamar.

  3. BioCores: identification of a drug/natural product-based privileged structural motif for small-molecule lead discovery.

    PubMed

    Kombarov, Roman; Altieri, Andrea; Genis, Dmitry; Kirpichenok, Mikhail; Kochubey, Valeriy; Rakitina, Natalia; Titarenko, Zoya

    2010-02-01

    The analysis of known drugs (Comprehensive Medicinal Chemistry database (2008 version): http://www.mdl.com/products/knowledge/medicinal_chem/index.jsp ) and natural products (Koch et al., Proc Natl Acad Sci USA 102:17272-17277, 2008) has led to the identification of privileged saturated and aromatic heterocyclic ring pairs that we have termed as "BioCores." This article explains how the BioCores can be used for the design of novel lead-like scaffolds.

  4. Historical and Future Black Carbon Deposition on the Three Ice Caps: Ice Core Measurements and Model Simulations from 1850 to 2100

    NASA Technical Reports Server (NTRS)

    Bauer, Susanne E.; Bausch, Alexandra; Nazarenko, Larissa; Tsigaridis, Kostas; Xu, Baiqing; Edwards. Ross; Bisiaux, Marion; McConnell, Joe

    2013-01-01

    Ice core measurements in conjunction with climate model simulations are of tremendous value when examining anthropogenic and natural aerosol loads and their role in past and future climates. Refractory black carbon (BC) records from the Arctic, the Antarctic, and the Himalayas are analyzed using three transient climate simulations performed with the Goddard Institute for Space Studies ModelE. Simulations differ in aerosol schemes (bulk aerosols vs. aerosol microphysics) and ocean couplings (fully coupled vs. prescribed ocean). Regional analyses for past (1850-2005) and future (2005-2100) carbonaceous aerosol simulations focus on the Antarctic, Greenland, and the Himalayas. Measurements from locations in the Antarctic show clean conditions with no detectable trend over the past 150 years. Historical atmospheric deposition of BC and sulfur in Greenland shows strong trends and is primarily influenced by emissions from early twentieth century agricultural and domestic practices. Models fail to reproduce observations of a sharp eightfold BC increase in Greenland at the beginning of the twentieth century that could be due to the only threefold increase in the North American emission inventory. BC deposition in Greenland is about 10 times greater than in Antarctica and 10 times less than in Tibet. The Himalayas show the most complicated transport patterns, due to the complex terrain and dynamical regimes of this region. Projections of future climate based on the four CMIP5 Representative Concentration Pathways indicate further dramatic advances of pollution to the Tibetan Plateau along with decreasing BC deposition fluxes in Greenland and the Antarctic.

  5. Historical and future black carbon deposition on the three ice caps: Ice core measurements and model simulations from 1850 to 2100

    NASA Astrophysics Data System (ADS)

    Bauer, Susanne E.; Bausch, Alexandra; Nazarenko, Larissa; Tsigaridis, Kostas; Xu, Baiqing; Edwards, Ross; Bisiaux, Marion; McConnell, Joe

    2013-07-01

    core measurements in conjunction with climate model simulations are of tremendous value when examining anthropogenic and natural aerosol loads and their role in past and future climates. Refractory black carbon (BC) records from the Arctic, the Antarctic, and the Himalayas are analyzed using three transient climate simulations performed with the Goddard Institute for Space Studies ModelE. Simulations differ in aerosol schemes (bulk aerosols vs. aerosol microphysics) and ocean couplings (fully coupled vs. prescribed ocean). Regional analyses for past (1850-2005) and future (2005-2100) carbonaceous aerosol simulations focus on the Antarctic, Greenland, and the Himalayas. Measurements from locations in the Antarctic show clean conditions with no detectable trend over the past 150 years. Historical atmospheric deposition of BC and sulfur in Greenland shows strong trends and is primarily influenced by emissions from early twentieth century agricultural and domestic practices. Models fail to reproduce observations of a sharp eightfold BC increase in Greenland at the beginning of the twentieth century that could be due to the only threefold increase in the North American emission inventory. BC deposition in Greenland is about 10 times greater than in Antarctica and 10 times less than in Tibet. The Himalayas show the most complicated transport patterns, due to the complex terrain and dynamical regimes of this region. Projections of future climate based on the four CMIP5 Representative Concentration Pathways indicate further dramatic advances of pollution to the Tibetan Plateau along with decreasing BC deposition fluxes in Greenland and the Antarctic.

  6. Using lead isotopes and trace element records from two contrasting Lake Tanganyika sediment cores to assess watershed – Lake exchange

    USGS Publications Warehouse

    Odigie, Kingsley; Cohen, A.D.; Swarzenski, Peter W.; Flegal, R

    2014-01-01

    Lead isotopic and trace element records of two contrasting sediment cores were examined to reconstruct historic, industrial contaminant inputs to Lake Tanganyika, Africa. Observed fluxes of Co, Cu, Mn, Ni, Pb, and Zn in age-dated sediments collected from the lake varied both spatially and temporally over the past two to four centuries. The fluxes of trace elements were lower (up to 10-fold) at a mid-lake site (MC1) than at a nearshore site (LT-98-58), which is directly downstream from the Kahama and Nyasanga River watersheds and adjacent to the relatively pristine Gombe Stream National Park. Trace element fluxes at that nearshore site did not measurably change over the last two centuries (1815–1998), while the distal, mid-lake site exhibited substantial changes in the fluxes of trace elements – likely caused by changes in land use – over that period. For example, the flux of Pb increased by ∼300% from 1871 to 1991. That apparent accelerated weathering and detrital mobilization of lithogenic trace elements was further evidenced by (i) positive correlations (r = 0.77–0.99, p < 0.05) between the fluxes of Co, Cu, Mn, Ni, Pb, and Zn and those of iron (Fe) at both sites, (ii) positive correlations (r = 0.82–0.98, p < 0.01, n = 9) between the fluxes of elements (Al, Co, Cu, Fe, Mn, Ni, Pb, and Zn) and the mass accumulation rates at the offshore site, (iii) the low enrichment factors (EF < 5) of those trace elements, and (iv) the temporal consistencies of the isotopic composition of Pb in the sediment. These measurements indicate that accelerated weathering, rather than industrialization, accounts for most of the increases in trace element fluxes to Lake Tanganyika in spite of the development of mining and smelting operations within the lake’s watershed over the past century. The data also indicate that the mid-lake site is a much more sensitive and useful recorder of environmental changes than the nearshore site. Furthermore, the lead isotopic compositions

  7. Fluorescence analysis of 6-mercaptopurine with the use of a nano-composite consisting of BSA-capped Au nano-clusters and core-shell Fe3O4-SiO2 nanoparticles.

    PubMed

    Li, Zhuo; Wang, Yong; Ni, Yongnian; Kokot, Serge

    2015-08-15

    A magnetic and fluorescent nano-composite was prepared. It comprised of a core of Fe3O4 nanoparticles (NPs), a silica shell and satellitic Au nano-clusters (AuNCs) capped with bovine serum albumin (BSA). This nano-composite has many desirable properties, e.g. magnetism, red emission, high water solubility, and high resistance to photo-bleaching. On addition of the analyte, 6-mercaptopurine (6-MP) or indeed other similar thiols, AuNCs formed aggregates because the existing cross-links within the Fe3O4 NPs@SiO2 and AuNC structure were broken in favor of the gold-thiol bonds. On suitable irradiation of such aggregates, red fluorescence was emitted at 613 nm. It decreased significantly as a function of the added 6-MP concentration, and the quenching ratio (F0 - F) / F0 was related linearly to the concentration of 6-MP in the range of 0.01 to 0.5 μmol L(-1). The detection limit was 0.004 μmol L(-1) (S/N=3). The method was strongly selective for 6-MP in the presence of oxidants, phenols, heavy-metal ions, and especially bio-thiols.

  8. Development of an unbonded capping system for clay masonry prisms

    SciTech Connect

    Crouch, L.K.; Henderson, R.C.; Sneed, W.A. Jr.

    1999-07-01

    To ascertain if an unbonded capping system was feasible for clay masonry prisms, the compressive strengths of thirty clay masonry prisms capped with an unbonded capping system modeled after ASTM C 1231 were compared with those of thirty masonry prisms capped with ASTM C 67 approved high-strength gypsum cement at the ages of 7 and 28 days. All prisms were constructed by a professional mason using Grade SW, Type FBS cored face brick from the same lot and ASTM C 270 Type S PC-lime mortar. There was no significant difference in mean compressive strength for the two capping methods at either age. In addition, capping with the unbonded capping system was faster and easier. Further, 28-day results obtained using the unbonded capping system had a lower coefficient of variation and higher mean compressive strength than those obtained with high-strength gypsum.

  9. The cervical cap (image)

    MedlinePlus

    The cervical cap is a flexible rubber cup-like device that is filled with spermicide and self-inserted over the cervix ... left in place several hours after intercourse. The cap is a prescribed device fitted by a health ...

  10. The size of the EB cap determines instantaneous microtubule stability.

    PubMed

    Duellberg, Christian; Cade, Nicholas I; Holmes, David; Surrey, Thomas

    2016-04-06

    The function of microtubules relies on their ability to switch between phases of growth and shrinkage. A nucleotide-dependent stabilising cap at microtubule ends is thought to be lost before this switch can occur; however, the nature and size of this protective cap are unknown. Using a microfluidics-assisted multi-colour TIRF microscopy assay with close-to-nm and sub-second precision, we measured the sizes of the stabilizing cap of individual microtubules. We find that the protective caps are formed by the extended binding regions of EB proteins. Cap lengths vary considerably and longer caps are more stable. Nevertheless, the trigger of instability lies in a short region at the end of the cap, as a quantitative model of cap stability demonstrates. Our study establishes the spatial and kinetic characteristics of the protective cap and provides an insight into the molecular mechanism by which its loss leads to the switch from microtubule growth to shrinkage.

  11. Cradle Cap: Treatment

    MedlinePlus

    Cradle cap Treatment Cradle cap usually doesn't require medical treatment. It clears up on its own within a few months. In the meantime, wash ... tips can help you control and manage cradle cap. Gently rub your baby's scalp with your fingers ...

  12. The cervical cap.

    PubMed

    1988-10-07

    The US Food and Drug Administration has approved marketing of the Prentif cavity-rim cervical cap. This contraceptive device is being distributed in the US and Canada by Cervical Cap Ltd, Los Gatos, California. The Prentif cap is available in 4 sizes: 22, 25, 28, and 31 mm inside diameter, with a length of 1 1/4-1 1/2 inches. In a multicenter trial involving 522 diaphragm users and 581 cap users followed for 2 years, the cap was 82.6% effective and the diaphragm was 83.3% effective in preventing pregnancy. When pregnancies attributable to user failure were excluded, these rates were increased to 93.6% for the cap and 95.4% for the diaphragm. 4% of cap users compared with only 1.7% of diaphragm users in this study developed abnormal Pap smears after 3 months of use; in addition, a higher proportion of cap users became infected with Gardnerella vaginalis and Monilia. Theoretical hazards include toxic shock syndrome and endometriosis due to backflow of menstrual fluids. Cap users are advised to undergo a Pap test after 3 months of use and discontinue cap use if the results are abnormal. The cap should not be used during menstruation. Although the cap can be left in place for up to 48 hours, its position should be checked before and after each episode of intercourse. The cervical cap requires less spermicide than the diaphragm and is not as messy. In addition, it can be left in the vagina twice as long as the diaphragm, without additional spermicide. Since the cap is smaller than the diaphragm and does not cover the vaginal wall, some women find intercourse more pleasurable with this device.

  13. Kinetics Parameters of VVER-1000 Core with 3 MOX Lead Test Assemblies To Be Used for Accident Analysis Codes

    SciTech Connect

    Pavlovitchev, A.M.

    2000-03-08

    The present work is a part of Joint U.S./Russian Project with Weapons-Grade Plutonium Disposition in VVER Reactor and presents the neutronics calculations of kinetics parameters of VVER-1000 core with 3 introduced MOX LTAs. MOX LTA design has been studied in [1] for two options of MOX LTA: 100% plutonium and of ''island'' type. As a result, zoning i.e. fissile plutonium enrichments in different plutonium zones, has been defined. VVER-1000 core with 3 introduced MOX LTAs of chosen design has been calculated in [2]. In present work, the neutronics data for transient analysis codes (RELAP [3]) has been obtained using the codes chain of RRC ''Kurchatov Institute'' [5] that is to be used for exploitation neutronics calculations of VVER. Nowadays the 3D assembly-by-assembly code BIPR-7A and 2D pin-by-pin code PERMAK-A, both with the neutronics constants prepared by the cell code TVS-M, are the base elements of this chain. It should be reminded that in [6] TVS-M was used only for the constants calculations of MOX FAs. In current calculations the code TVS-M has been used both for UOX and MOX fuel constants. Besides, the volume of presented information has been increased and additional explications have been included. The results for the reference uranium core [4] are presented in Chapter 2. The results for the core with 3 MOX LTAs are presented in Chapter 3. The conservatism that is connected with neutronics parameters and that must be taken into account during transient analysis calculations, is discussed in Chapter 4. The conservative parameters values are considered to be used in 1-point core kinetics models of accident analysis codes.

  14. Vinyl capped addition polyimides

    NASA Technical Reports Server (NTRS)

    Vannucci, Raymond D. (Inventor); Malarik, Diane C. (Inventor); Delvigs, Peter (Inventor)

    1991-01-01

    Polyimide resins (PMR) are generally useful where high strength and temperature capabilities are required (at temperatures up to about 700 F). Polyimide resins are particularly useful in applications such as jet engine compressor components, for example, blades, vanes, air seals, air splitters, and engine casing parts. Aromatic vinyl capped addition polyimides are obtained by reacting a diamine, an ester of tetracarboxylic acid, and an aromatic vinyl compound. Low void materials with improved oxidative stability when exposed to 700 F air may be fabricated as fiber reinforced high molecular weight capped polyimide composites. The aromatic vinyl capped polyimides are provided with a more aromatic nature and are more thermally stable than highly aliphatic, norbornenyl-type end-capped polyimides employed in PMR resins. The substitution of aromatic vinyl end-caps for norbornenyl end-caps in addition polyimides results in polymers with improved oxidative stability.

  15. Case Studies of Leading Edge Small Urban High Schools. Core Academic Strategic Designs: 2. Noble Street Charter High School

    ERIC Educational Resources Information Center

    Shields, Regis Anne; Ireland, Nicole; City, Elizabeth; Derderian, Julie; Miles, Karen Hawley

    2008-01-01

    This report is one of nine detailed case studies of small urban high schools that served as the foundation for the Education Resource Strategies (ERS) report "Strategic Designs: Lessons from Leading Edge Small Urban High Schools." These nine schools were dubbed "Leading Edge Schools" because they stand apart from other high…

  16. Light-curve and spectral properties of ultrastripped core-collapse supernovae leading to binary neutron stars

    NASA Astrophysics Data System (ADS)

    Moriya, Takashi J.; Mazzali, Paolo A.; Tominaga, Nozomu; Hachinger, Stephan; Blinnikov, Sergei I.; Tauris, Thomas M.; Takahashi, Koh; Tanaka, Masaomi; Langer, Norbert; Podsiadlowski, Philipp

    2017-04-01

    We investigate light-curve and spectral properties of ultrastripped core-collapse supernovae. Ultrastripped supernovae are the explosions of heavily stripped massive stars that lost their envelopes via binary interactions with a compact companion star. They eject only ˜0.1 M⊙ and may be the main way to form double neutron-star systems that eventually merge emitting strong gravitational waves. We follow the evolution of an ultrastripped supernova progenitor until iron core collapse and perform explosive nucleosynthesis calculations. We then synthesize light curves and spectra of ultrastripped supernovae using the nucleosynthesis results and present their expected properties. Ultrastripped supernovae synthesize ˜0.01 M⊙ of radioactive 56Ni, and their typical peak luminosity is around 1042 erg s-1 or -16 mag. Their typical rise time is 5-10 d. Comparing synthesized and observed spectra, we find that SN 2005ek, some of the so-called calcium-rich gap transients, and SN 2010X may be related to ultrastripped supernovae. If these supernovae are actually ultrastripped supernovae, their event rate is expected to be about 1 per cent of core-collapse supernovae. Comparing the double neutron-star merger rate obtained by future gravitational-wave observations and the ultrastripped supernova rate obtained by optical transient surveys identified with our synthesized light-curve and spectral models, we will be able to judge whether ultrastripped supernovae are actually a major contributor to the binary neutron-star population and provide constraints on binary stellar evolution.

  17. Claymax landfill cap

    SciTech Connect

    Selby, C.L.

    1989-12-15

    A commercial product called Claymax'' consisting of one-quarter inch of bentonite clay between two geotextile sheets is a candidate landfill cap to replace kaolin caps. A permeability apparatus incorporating a 20 foot water head was operated for 56 days to estimate a Claymax permeability of 2 {times} 10{sup {minus}9} cm/sec compared with 10{sup {minus}8}, the EPA max for a burial site cap. 1 fig.

  18. Health-care cap.

    PubMed

    1996-05-03

    Dallas Avionics agreed to discontinue its cap on HIV-related medical expenses. The Texas company offered employees $1 million worth of lifetime medical benefits, with the exception of HIV-related expenses. Lambda Legal Defense and Education Fund intervened, demanding that the cap be removed and the company pay an employee's $82,000 outstanding HIV-related medical bills. According to Lambda, the cap violates the Americans with Disabilities Act (ADA).

  19. Antarctic-wide array of high-resolution ice core records reveals pervasive lead pollution began in 1889 and persists today

    PubMed Central

    McConnell, J. R.; Maselli, O. J.; Sigl, M.; Vallelonga, P.; Neumann, T.; Anschütz, H.; Bales, R. C.; Curran, M. A. J.; Das, S. B.; Edwards, R.; Kipfstuhl, S.; Layman, L.; Thomas, E. R.

    2014-01-01

    Interior Antarctica is among the most remote places on Earth and was thought to be beyond the reach of human impacts when Amundsen and Scott raced to the South Pole in 1911. Here we show detailed measurements from an extensive array of 16 ice cores quantifying substantial toxic heavy metal lead pollution at South Pole and throughout Antarctica by 1889 – beating polar explorers by more than 22 years. Unlike the Arctic where lead pollution peaked in the 1970s, lead pollution in Antarctica was as high in the early 20th century as at any time since industrialization. The similar timing and magnitude of changes in lead deposition across Antarctica, as well as the characteristic isotopic signature of Broken Hill lead found throughout the continent, suggest that this single emission source in southern Australia was responsible for the introduction of lead pollution into Antarctica at the end of the 19th century and remains a significant source today. An estimated 660 t of industrial lead have been deposited over Antarctica during the past 130 years as a result of mid-latitude industrial emissions, with regional-to-global scale circulation likely modulating aerosol concentrations. Despite abatement efforts, significant lead pollution in Antarctica persists into the 21st century. PMID:25068819

  20. Antarctic-wide array of high-resolution ice core records reveals pervasive lead pollution began in 1889 and persists today

    NASA Astrophysics Data System (ADS)

    McConnell, J. R.; Maselli, O. J.; Sigl, M.; Vallelonga, P.; Neumann, T.; Anschütz, H.; Bales, R. C.; Curran, M. A. J.; Das, S. B.; Edwards, R.; Kipfstuhl, S.; Layman, L.; Thomas, E. R.

    2014-07-01

    Interior Antarctica is among the most remote places on Earth and was thought to be beyond the reach of human impacts when Amundsen and Scott raced to the South Pole in 1911. Here we show detailed measurements from an extensive array of 16 ice cores quantifying substantial toxic heavy metal lead pollution at South Pole and throughout Antarctica by 1889 - beating polar explorers by more than 22 years. Unlike the Arctic where lead pollution peaked in the 1970s, lead pollution in Antarctica was as high in the early 20th century as at any time since industrialization. The similar timing and magnitude of changes in lead deposition across Antarctica, as well as the characteristic isotopic signature of Broken Hill lead found throughout the continent, suggest that this single emission source in southern Australia was responsible for the introduction of lead pollution into Antarctica at the end of the 19th century and remains a significant source today. An estimated 660 t of industrial lead have been deposited over Antarctica during the past 130 years as a result of mid-latitude industrial emissions, with regional-to-global scale circulation likely modulating aerosol concentrations. Despite abatement efforts, significant lead pollution in Antarctica persists into the 21st century.

  1. Antarctic-wide array of high-resolution ice core records reveals pervasive lead pollution began in 1889 and persists today.

    PubMed

    McConnell, J R; Maselli, O J; Sigl, M; Vallelonga, P; Neumann, T; Anschütz, H; Bales, R C; Curran, M A J; Das, S B; Edwards, R; Kipfstuhl, S; Layman, L; Thomas, E R

    2014-07-28

    Interior Antarctica is among the most remote places on Earth and was thought to be beyond the reach of human impacts when Amundsen and Scott raced to the South Pole in 1911. Here we show detailed measurements from an extensive array of 16 ice cores quantifying substantial toxic heavy metal lead pollution at South Pole and throughout Antarctica by 1889 - beating polar explorers by more than 22 years. Unlike the Arctic where lead pollution peaked in the 1970s, lead pollution in Antarctica was as high in the early 20(th) century as at any time since industrialization. The similar timing and magnitude of changes in lead deposition across Antarctica, as well as the characteristic isotopic signature of Broken Hill lead found throughout the continent, suggest that this single emission source in southern Australia was responsible for the introduction of lead pollution into Antarctica at the end of the 19(th) century and remains a significant source today. An estimated 660 t of industrial lead have been deposited over Antarctica during the past 130 years as a result of mid-latitude industrial emissions, with regional-to-global scale circulation likely modulating aerosol concentrations. Despite abatement efforts, significant lead pollution in Antarctica persists into the 21(st) century.

  2. Antarctic-Wide Array of High-Resolution Ice Core Records Reveals Pervasive Lead Pollution Began in 1889 and Persists Today

    NASA Technical Reports Server (NTRS)

    McConnell, J. R.; Maselli, O. J.; Sigl, M.; Vallelonga, P.; Neumann, Thomas Allen; Anschutz, H.; Bales, R. C.; Curran, M. A. J.; Das, S. B.; Edwards, R.; hide

    2014-01-01

    Interior Antarctica is among the most remote places on Earth and was thought to be beyond the reach of human impacts when Amundsen and Scott raced to the South Pole in 1911. Here we show detailed measurements from an extensive array of 16 ice cores quantifying substantial toxic heavy metal lead pollution at South Pole and throughout Antarctica by 1889 - beating polar explorers by more than 22 years. Unlike the Arctic where lead pollution peaked in the 1970s, lead pollution in Antarctica was as high in the early 20th century as at any time since industrialization. The similar timing and magnitude of changes in lead deposition across Antarctica, as well as the characteristic isotopic signature of Broken Hill lead found throughout the continent, suggest that this single emission source in southern Australia was responsible for the introduction of lead pollution into Antarctica at the end of the 19th century and remains a significant source today. An estimated 660 t of industrial lead have been deposited over Antarctica during the past 130 years as a result of mid-latitude industrial emissions, with regional-to-global scale circulation likely modulating aerosol concentrations. Despite abatement efforts, significant lead pollution in Antarctica persists into the 21st century.

  3. Lead users’ ideas on core features to support physical activity in rheumatoid arthritis: a first step in the development of an internet service using participatory design

    PubMed Central

    2014-01-01

    Background Despite the growing evidence of the benefits of physical activity (PA) in individuals with rheumatoid arthritis (RA), the majority is not physically active enough. An innovative strategy is to engage lead users in the development of PA interventions provided over the internet. The aim was to explore lead users’ ideas and prioritization of core features in a future internet service targeting adoption and maintenance of healthy PA in people with RA. Methods Six focus group interviews were performed with a purposively selected sample of 26 individuals with RA. Data were analyzed with qualitative content analysis and quantification of participants’ prioritization of most important content. Results Six categories were identified as core features for a future internet service: up-to-date and evidence-based information and instructions, self-regulation tools, social interaction, personalized set-up, attractive design and content, and access to the internet service. The categories represented four themes, or core aspects, important to consider in the design of the future service: (1) content, (2) customized options, (3) user interface and (4) access and implementation. Conclusions This is, to the best of our knowledge, the first study involving people with RA in the development of an internet service to support the adoption and maintenance of PA. Participants helped identifying core features and aspects important to consider and further explore during the next phase of development. We hypothesize that involvement of lead users will make transfer from theory to service more adequate and user-friendly and therefore will be an effective mean to facilitate PA behavior change. PMID:24655757

  4. Lead users' ideas on core features to support physical activity in rheumatoid arthritis: a first step in the development of an internet service using participatory design.

    PubMed

    Revenäs, Åsa; Opava, Christina H; Åsenlöf, Pernilla

    2014-03-22

    Despite the growing evidence of the benefits of physical activity (PA) in individuals with rheumatoid arthritis (RA), the majority is not physically active enough. An innovative strategy is to engage lead users in the development of PA interventions provided over the internet. The aim was to explore lead users' ideas and prioritization of core features in a future internet service targeting adoption and maintenance of healthy PA in people with RA. Six focus group interviews were performed with a purposively selected sample of 26 individuals with RA. Data were analyzed with qualitative content analysis and quantification of participants' prioritization of most important content. Six categories were identified as core features for a future internet service: up-to-date and evidence-based information and instructions, self-regulation tools, social interaction, personalized set-up, attractive design and content, and access to the internet service. The categories represented four themes, or core aspects, important to consider in the design of the future service: (1) content, (2) customized options, (3) user interface and (4) access and implementation. This is, to the best of our knowledge, the first study involving people with RA in the development of an internet service to support the adoption and maintenance of PA.Participants helped identifying core features and aspects important to consider and further explore during the next phase of development. We hypothesize that involvement of lead users will make transfer from theory to service more adequate and user-friendly and therefore will be an effective mean to facilitate PA behavior change.

  5. Synthesis of a des-B-ring bryostatin analogue leads to an unexpected ring expansion of the bryolactone core.

    PubMed

    Kraft, Matthew B; Poudel, Yam B; Kedei, Noemi; Lewin, Nancy E; Peach, Megan L; Blumberg, Peter M; Keck, Gary E

    2014-09-24

    A convergent synthesis of a des-B-ring bryostatin analogue is described. This analogue was found to undergo an unexpected ring expansion of the bryolactone core to generate the corresponding 21-membered macrocycle. The parent analogue and the ring-expanded product both displayed nanomolar binding affinity for PKC. Despite containing A-ring substitution identical to that of bryostatin 1 and displaying bryostatin-like biological function, the des-B-ring analogues displayed a phorbol-like biological function in cells. These studies shed new light on the role of the bryostatin B-ring in conferring bryo-like biological function to bryostatin analogues.

  6. Synthesis of a des-B-Ring Bryostatin Analogue Leads to an Unexpected Ring Expansion of the Bryolactone Core

    PubMed Central

    2015-01-01

    A convergent synthesis of a des-B-ring bryostatin analogue is described. This analogue was found to undergo an unexpected ring expansion of the bryolactone core to generate the corresponding 21-membered macrocycle. The parent analogue and the ring-expanded product both displayed nanomolar binding affinity for PKC. Despite containing A-ring substitution identical to that of bryostatin 1 and displaying bryostatin-like biological function, the des-B-ring analogues displayed a phorbol-like biological function in cells. These studies shed new light on the role of the bryostatin B-ring in conferring bryo-like biological function to bryostatin analogues. PMID:25207434

  7. Synthesis of Leishmania cap-4 intermediates, cap-2 and cap-3.

    PubMed

    Lewdorowicz, Magdalena; Stepinski, Janusz; Kierzek, Ryszard; Jemielity, Jacek; Zuberek, Joanna; Yoffe, Yael; Shapira, Michal; Stolarski, Ryszard; Darzynkiewicz, Edward

    2007-01-01

    Synthesis of Leishmania mRNA 5'-cap analogs, m(7)Gpppm(2)(6)AmpAm (cap-2), and m(7)Gpppm(2)(6)AmpAmpCm (cap-3) is reported. Binding affinities of those cap analogs for LeishIF4E proteins were determined using fluorescence spectroscopy. Cap-3 showed similar affinity to LeishIF4Es compared to the mature trypanosomatids cap structure (cap-4).

  8. Mars ice caps.

    PubMed

    Leovy, C

    1966-12-02

    Minimum atmospheric temperatures required to prevent CO(2) condensatio in the Mars polar caps are higher than those obtained in a computer experiment to simulate the general circulation of the Mars atmosphere. This observation supports the view that the polar caps are predominantly solid CO(2). However, thin clouds of H(2)0 ice could substantially reduce the surface condensation rate.

  9. Recent applications of 1,3-thiazole core structure in the identification of new lead compounds and drug discovery.

    PubMed

    Ayati, Adile; Emami, Saeed; Asadipour, Ali; Shafiee, Abbas; Foroumadi, Alireza

    2015-06-05

    1,3-Thiazole is one of the most important scaffolds in heterocyclic chemistry and drug design and discovery. It is widely found in diverse pharmacologically active substances and in some naturally-occurring compounds. Thiazole is a versatile building-block for lead generation, and is easily access of diverse derivatives for subsequent lead optimization. In the recent years, many thiazole derivatives have been synthesized and subjected to varied biological activities. In this article we intended to review the most important biological effects of thiazole-based compounds and highlight their roles in new leads identification and drug discovery. This article is also intended to help researches for finding potential future directions on the development of more potent and specific analogs of thiazole-based compounds for various biological targets.

  10. Lead-Cooled Fast Reactor (LFR) Design: Safety, Neutronics, Thermal Hydraulics, Structural Mechanics, Fuel, Core, and Plant Design

    SciTech Connect

    Smith, C

    2010-02-22

    The idea of developing fast spectrum reactors with molten lead (or lead alloy) as a coolant is not a new one. Although initially considered in the West in the 1950s, such technology was not pursued to completion because of anticipated difficulties associated with the corrosive nature of these coolant materials. However, in the Soviet Union, such technology was actively pursued during the same time frame (1950s through the 1980s) for the specialized role of submarine propulsion. More recently, there has been a renewal of interest in the West for such technology, both for critical systems as well as for Accelerator Driven Subcritical (ADS) systems. Meanwhile, interest in the former Soviet Union, primarily Russia, has remained strong and has expanded well beyond the original limited mission of submarine propulsion. This section reviews the past and current status of LFR development.

  11. Chronic intermittent ethanol exposure and withdrawal leads to adaptations in nucleus accumbens core postsynaptic density proteome and dendritic spines.

    PubMed

    Uys, Joachim D; McGuier, Natalie S; Gass, Justin T; Griffin, William C; Ball, Lauren E; Mulholland, Patrick J

    2016-05-01

    Alcohol use disorder is a chronic relapsing brain disease characterized by the loss of ability to control alcohol (ethanol) intake despite knowledge of detrimental health or personal consequences. Clinical and pre-clinical models provide strong evidence for chronic ethanol-associated alterations in glutamatergic signaling and impaired synaptic plasticity in the nucleus accumbens (NAc). However, the neural mechanisms that contribute to aberrant glutamatergic signaling in ethanol-dependent individuals in this critical brain structure remain unknown. Using an unbiased proteomic approach, we investigated the effects of chronic intermittent ethanol (CIE) exposure on neuroadaptations in postsynaptic density (PSD)-enriched proteins in the NAc of ethanol-dependent mice. Compared with controls, CIE exposure significantly changed expression levels of 50 proteins in the PSD-enriched fraction. Systems biology and functional annotation analyses demonstrated that the dysregulated proteins are expressed at tetrapartite synapses and critically regulate cellular morphology. To confirm this latter finding, the density and morphology of dendritic spines were examined in the NAc core of ethanol-dependent mice. We found that CIE exposure and withdrawal differentially altered dendrite diameter and dendritic spine density and morphology. Through the use of quantitative proteomics and functional annotation, these series of experiments demonstrate that ethanol dependence produces neuroadaptations in proteins that modify dendritic spine morphology. In addition, these studies identified novel PSD-related proteins that contribute to the neurobiological mechanisms of ethanol dependence that drive maladaptive structural plasticity of NAc neurons. © 2015 Society for the Study of Addiction.

  12. Gold(Core)-Lead(Shell) Nanoparticle-Loaded Titanium(IV) Oxide Prepared by Underpotential Photodeposition: Plasmonic Water Oxidation.

    PubMed

    Negishi, Ryo; Naya, Shin-Ichi; Kobayashi, Hisayoshi; Tada, Hiroaki

    2017-08-21

    Underpotential photodeposition of Pb yields an ultrathin shell layer on the Au(111) surface of Au nanoparticle(NP)-loaded TiO2 (Au/TiO2 ) with heteroepitaxial nanojunctions. The localized surface plasmon resonance of Au/TiO2 undergoes no damping with the Pb-shell formation, and the Pb shell offers resistance to aerobic oxidation. Mesoporous films comprising the Au(core)-Pb(shell) NP-loaded TiO2 and unmodified Au/TiO2 were formed on fluorine-doped tin oxide (FTO) electrode. Using them as the photoanode, photoelectrochemical cells were fabricated, and the photocurrent was measured under illumination of simulated sunlight. The photocurrent for water splitting is dramatically enhanced by the Pb-shell formation. The photoelectrochemical measurements of the hot-electron lifetime and density functional theory calculations for model clusters indicate that the Pb-shell effect originates from the charge separation enhancement. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Correlation of the neutron star crust-core properties with the slope of the symmetry energy and the lead skin thickness

    NASA Astrophysics Data System (ADS)

    Pais, H.; Sulaksono, A.; Agrawal, B. K.; Providência, C.

    2016-04-01

    The correlations of the crust-core transition density and pressure in neutron stars with the slope of the symmetry energy and the neutron skin thickness are investigated, using different families of relativistic mean-field parametrizations with constant couplings and nonlinear terms mixing the σ - , ω - , and ρ -meson fields. It is shown that the modification of the density dependence of the symmetry energy, involving the σ or the ω meson, gives rise to different behaviors: the effect of the ω meson may also be reproduced within nonrelativistic phenomenological models, while the effect of the σ meson is essentially relativistic. Depending on the parametrization with σ -ρ or ω -ρ mixing terms, different values of the slope of the symmetry energy at saturation must be considered in order to obtain a neutron matter equation of state compatible with results from chiral effective field theory. This difference leads to different pressures at the crust-core transition density. A linear correlation between the transition density and the symmetry energy slope or the neutron skin thickness of the 208Pb nucleus is obtained, only when the ω meson is used to describe the density dependence of the symmetry energy. A comparison is made between the crust-core transition properties of neutron stars obtained by three different methods, the relativistic random phase approximation (RRPA), the Vlasov equation, and thermodynamical method. It is shown that the RRPA and the Vlasov methods predict similar transition densities for p n e β -equilibrium stellar matter.

  14. Precise Tuning of the Nanostructured Surface leading to the Luminescence Enhancement in SrAl2O4 Based Core/Shell Structure.

    PubMed

    Rojas-Hernandez, Rocío Estefanía; Rubio-Marcos, Fernando; Serrano, Aida; Del Campo, Adolfo; Fernandez, José Francisco

    2017-03-28

    Intensive research has been focused on the synthesis of long-lasting SrAl2O4:EuDy in luminescent materials field. Traditionally, SrAl2O4:EuDy is synthesized in bulk form by solid state. However, their development remains restrained due to this technique is not compatible with large-scale production, sustainability and nanometer-scale requirements. Despite nano-range particles have been obtained by chemical routes, photoluminescence response decreases and application became unpractical. It remains a challenge to synthesize nonrare-earth (RE) phosphors with high photoluminescence. One major challenge for the luminescent materials community is to devise methods to deliver innovative, sustainable and cost effective solutions for the reduction of RE because of the lack of RE availability. Here, we suggest a solution based on molten salts, obtaining nanosheets or micro/nanostructured SrAl2O4:Eu, Dy particles with core-shell structure, employing only 50% of standard amounts of RE. Core-size and shell thickness and crystallinity can be tuned by post-thermal treatment, through which can be modulated the Eu(+2) fraction. We find that our methodology leads the functional features of the analogous micron counterpart. These results can be considered a great achievement to scale-up the process. Besides, the harmful collateral effect of nanotechnology must be addressed by using new safe by design core-shell nanostructures.

  15. Water-resistant, monodispersed and stably luminescent CsPbBr3/CsPb2Br5 core-shell like structure lead halide perovskite nanocrystals.

    PubMed

    Qiao, Bo; Song, Pengjie; Cao, Jingyue; Zhao, Suling; Shen, Zhaohui; Gao, Di; Liang, Zhiqin; Xu, Zheng; Song, Dandan; Xu, Xurong

    2017-08-30

    Lead halide perovskite materials are blooming for optoelectronic applications due to their excellent properties, while their instability due to their extreme ease for hydrolysis is still a bottleneck for their potential applications. In this work, water-resistant, monodispersed and stably luminescent cesium lead bromine perovskite nanocrystals coated with CsPb2Br5 were obtained with modified non-stoichiometric solution-phase method. CsPb2Br5 2D layers coated on the surface of CsPbBr3 nanocrystals and formed core-shell like structure in the synthetic processes. The stability of luminescence of CsPbBr3 nanocrystals in water and ethanol atmosphere was greatly enhanced by the PL-inactive CsPb2Br5-coating with wide bandgap. The water-stable-enhanced NCs pave a pathway for more stable QLED applications and even biological fluorescence detection applications. © 2017 IOP Publishing Ltd.

  16. CCiCap: Boeing

    NASA Image and Video Library

    NASA announced today its plans to partner with The Boeing Company for the next phase of the agency's Commercial Crew Program (CCP). Called Commercial Crew integrated Capability (CCiCap), the initia...

  17. CENTRIFUGE END CAP

    DOEpatents

    Beams, J.W.; Snoddy, L.B.

    1960-08-01

    An end cap for ultra-gas centrifuges is designed to impart or remove angular momentum to or from the gas and to bring the entering gas to the temperature of the gas inside the centrifuge. The end cap is provided with slots or fins for adjusting the temperature and the angular momentum of the entering gas to the temperature and momentum of the gas in the centrifuge and is constructed to introduce both the inner and the peripheral stream into the centrifuge.

  18. ROTOR END CAP

    DOEpatents

    Rushing, F.C.

    1959-02-01

    An improved end cap is described for the cylindrical rotor or bowl of a high-speed centrifugal separator adapted to permit free and efficient continuous counter current flow of gas therethrough for isotope separation. The end cap design provides for securely mounting the same to the hollow central shaft and external wall of the centrifuge. Passageways are incorporated and so arranged as to provide for continuous counter current flow of the light and heavy portions of the gas fed to the centrifuge.

  19. Photoactivable caps for reactive metal nanoparticles

    NASA Astrophysics Data System (ADS)

    Patel, Ashish

    The synthesis and stabilization of reactive metal nanoparticles is often challenging under normal atmospheric conditions. This problem can be alleviated by capping and passivation. Our lab has focused on forming polymer coatings on the surface of reactive metal nanoparticles. We discovered a convenient and effective route for stabilization of aluminum nanoparticles (Al NPs), which uses the nascent metal core as a polymerization initiator for various organic monomers. In our previous work, we used this method to passivate the Al NPs using variety of epoxides and copolymers of epoxides and alkenes. These products have demonstrated air stability for weeks to months with little to no degradation in the active Al content. Since our previously synthesized Al NP's were not beneficial for rapid and efficient thermodynamic access to the active Al core, our goal was find polymers that could easily be photochemically activated to enhance such access. Since poly(methyl methacrylate) (PMMA) has photodegrading properties, we used PMMA as a capping agent to passivate Al NPs. In this work, we present capping and stabilization of Al NPs with PMMA, and also with 1,2-epoxyhexane/ PMMA. In our previous work, we increased the stability of Al NP capped with 1,2-epoxy-9-decene by adding 1,13-tetradecadiene as a cross-linker. Here, we used the methyl methacrylate (MMA) monomer as cross-linker for Al NP capped with 1,2-epoxy-9-decene. We have also used the MMA as capping agent. We use powder x-ray diffractametry (PXRD), differential scanning calorimetry (DSC), and thermogravity analysis (TGA) to confirm the presence of elemental Al and ATR-FTIR to confirm the presence of polymers.

  20. Catastrophic antiphospholipid syndrome (CAPS): Descriptive analysis of 500 patients from the International CAPS Registry.

    PubMed

    Rodríguez-Pintó, Ignasi; Moitinho, Marta; Santacreu, Irene; Shoenfeld, Yehuda; Erkan, Doruk; Espinosa, Gerard; Cervera, Ricard

    2016-12-01

    To analyze the clinical and immunologic manifestations of patients with catastrophic antiphospholipid syndrome (CAPS) from the "CAPS Registry". The demographic, clinical and serological features of 500 patients included in the website-based "CAPS Registry" were analyzed. Frequency distribution and measures of central tendency were used to describe the cohort. Comparison between groups regarding qualitative variables was undertaken by chi-square or Fisher exact test while T-test for independent variables was used to compare groups regarding continuous variables. 500 patients (female: 343 [69%]; mean age 38±17) accounting for 522 episodes of CAPS were included in the analysis. Forty percent of patients had an associated autoimmune disease, mainly systemic lupus erythematosus (SLE) (75%). The majority of CAPS episodes were triggered by a precipitating factor (65%), mostly infections (49%). Clinically, CAPS was characterized by several organ involvement affecting kidneys (73%), lungs (60%), brain (56%), heart (50%), and skin (47%). Lupus anticoagulant, IgG anticardiolipin and IgG anti-β2-glycprotein antibodies were the most often implicated antiphospholipid antibodies (83%, 81% and 78% respectively). Mortality accounted for 37% of episodes of CAPS. Several clinical differences could be observed based on the age of presentation and its association to SLE. Those cases triggered by a malignancy tended to occur in older patients, while CAPS episodes in young patients were associated with an infectious trigger and peripheral vessels involvement. Additionally, CAPS associated with SLE were more likely to have severe cardiac and brain involvement leading to a higher mortality (48%). Although the presentation of CAPS is characterized by multiorgan thrombosis and failure, clinical differences among patients exist based on age and underlying chronic diseases, e.g. malignancy and SLE. Copyright © 2016 Elsevier B.V. All rights reserved.

  1. CAPS Simulation Environment Development

    NASA Technical Reports Server (NTRS)

    Murphy, Douglas G.; Hoffman, James A.

    2005-01-01

    The final design for an effective Comet/Asteroid Protection System (CAPS) will likely come after a number of competing designs have been simulated and evaluated. Because of the large number of design parameters involved in a system capable of detecting an object, accurately determining its orbit, and diverting the impact threat, a comprehensive simulation environment will be an extremely valuable tool for the CAPS designers. A successful simulation/design tool will aid the user in identifying the critical parameters in the system and eventually allow for automatic optimization of the design once the relationships of the key parameters are understood. A CAPS configuration will consist of space-based detectors whose purpose is to scan the celestial sphere in search of objects likely to make a close approach to Earth and to determine with the greatest possible accuracy the orbits of those objects. Other components of a CAPS configuration may include systems for modifying the orbits of approaching objects, either for the purpose of preventing a collision or for positioning the object into an orbit where it can be studied or used as a mineral resource. The Synergistic Engineering Environment (SEE) is a space-systems design, evaluation, and visualization software tool being leveraged to simulate these aspects of the CAPS study. The long-term goal of the SEE is to provide capabilities to allow the user to build and compare various CAPS designs by running end-to-end simulations that encompass the scanning phase, the orbit determination phase, and the orbit modification phase of a given scenario. Herein, a brief description of the expected simulation phases is provided, the current status and available features of the SEE software system is reported, and examples are shown of how the system is used to build and evaluate a CAPS detection design. Conclusions and the roadmap for future development of the SEE are also presented.

  2. Mechanical properties at high strain-rate of lead core and brass jacket of a NATO 7.62 mm ball bullet

    NASA Astrophysics Data System (ADS)

    Peroni, L.; Scapin, M.; Fichera, C.; Manes, A.; Giglio, M.

    2012-08-01

    Numerical simulations are now an actual option in order to try to reproduce and understand the mechanical response in components subjected to extreme loading conditions, like in a ballistic impact. A correct materials calibration is therefore necessary in order to extract the materials parameters. In this work the simple and widely used Johnson-Cook model was used to analyse the experimental data obtained for the characterization of the bullet materials. The bullet under investigation is a full metal jacket ball, with a lead-antimony alloy core and a brass jacket. The experimental tests cover a wide range in strain-rate, starting from quasi-static tests up to high dynamic tests performed on a standard Split Hopkinson Pressure Bar setup. In general, there is a great lack in strain-rate sensitivity and failure data. Pure lead is very soft and ductile, so antimony is used to give greater hardness and strength. The results of this study show a significant strain-rate influence for this alloy that can be associated with the presence of the lead-antimony phases and their structures. Also in case of the brass the results showed significant strain-rate sensitivity in the material response.

  3. X gene/core promoter deletion mutation: a novel mechanism leading to hepatitis B 'e' antigen‑negative chronic hepatitis B.

    PubMed

    Zhou, Fei; Xu, Hongzhi; Chen, Meiya; Xiao, Hongmin; Zhang, Zhiping; Lu, Yapi; Ren, Jianlin; Dong, Jing

    2014-08-01

    Mutations in the precore and core promoter regions of hepatitis B 'e' antigen (HBeAg) are implicated in HBeAg‑negative chronic hepatitis B virus (HBV) infection (CHB). The objective of the current study was to investigate novel mutant patterns that lead to HBeAg‑negative CHB. The . PreX-X genomic region from the sera of HBV‑infected patients was amplified, and analysis of the sequences displayed a unique deletion region, 234 nucleotides in length, which was observed in 54 clones and named core promoter deletion (CPD). CPD may have an important role in the cause of HBeAg‑negative CHB. In addition, a novel deletion mutation in the X gene was observed in patients with CHB. This deletion mutant codes a 76‑amino‑acid X factor instead of the X protein. In the present study, a new mutation pattern was discovered that may contribute to the cause of HBeAg-negative CHB, and therefore it is worthy of future studies.

  4. Lead optimization of the VU0486321 series of mGlu1 PAMs. Part 1: SAR of modifications to the central aryl core.

    PubMed

    Garcia-Barrantes, Pedro M; Cho, Hyekyung P; Blobaum, Anna L; Niswender, Colleen M; Conn, P Jeffrey; Lindsley, Craig W

    2015-11-15

    This Letter describes the lead optimization of the VU0486321 series of mGlu1 positive allosteric modulators (PAMs). While first generation PAMs from Roche were reported in the late 1990s, little effort has focused on the development of mGlu1 PAMs since. New genetic data linking loss-of-function mutant mGlu1 receptors to schizophrenia, bipolar disorder and other neuropsychiatric disorders has rekindled interest in the target, but the ideal in vivo probe, for example, with good PK, brain penetration and low plasma protein binding, for robust target validation has been lacking. Here we describe the first modifications to the central aryl core of the VU0486321 series, where robust SAR was noted. Moreover, structural variants were identified that imparted selectivity (up to >793-fold) versus mGlu4.

  5. North Polar Cap

    NASA Technical Reports Server (NTRS)

    2004-01-01

    7 September 2004 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a 1.4 m/pixel (5 ft/pixel) view of a typical martian north polar ice cap texture. The surface is pitted and rough at the scale of several meters. The north polar residual cap of Mars consists mainly of water ice, while the south polar residual cap is mostly carbon dioxide. This picture is located near 85.2oN, 283.2oW. The image covers an area approximately 1 km wide by 1.4 km high (0.62 by 0.87 miles). Sunlight illuminates this scene from the lower left.

  6. North Polar Cap

    NASA Technical Reports Server (NTRS)

    2004-01-01

    7 September 2004 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a 1.4 m/pixel (5 ft/pixel) view of a typical martian north polar ice cap texture. The surface is pitted and rough at the scale of several meters. The north polar residual cap of Mars consists mainly of water ice, while the south polar residual cap is mostly carbon dioxide. This picture is located near 85.2oN, 283.2oW. The image covers an area approximately 1 km wide by 1.4 km high (0.62 by 0.87 miles). Sunlight illuminates this scene from the lower left.

  7. Magnetospheric polar cap

    NASA Astrophysics Data System (ADS)

    Akasofu, S. I.; Kan, J. R.

    Mount Denali (McKinley), the Alaska Range, and countless glaciers welcomed all 86 participants of the Chapman Conference on the Magnetospheric Polar Cap, which was held on the University of Alaska, Fairbanks campus (UAF), on August 6-9, 1984. The magnetospheric polar cap is the highest latitude region of the earth which is surrounded by the ring of auroras (the auroral oval). This particular region of the earth has become a focus of magnetospheric physicists during the last several years. This is because a number of upper atmospheric phenomena in the polar cap are found to be crucial in understanding the solar wind—magnetosphere interaction. The conference was opened by J. G. Roederer, who was followed by the UAF Chancellor, P. J. O'Rourke, who officially welcomed the participants.

  8. [Capping strategies in RNA viruses].

    PubMed

    Bouvet, Mickaël; Ferron, François; Imbert, Isabelle; Gluais, Laure; Selisko, Barbara; Coutard, Bruno; Canard, Bruno; Decroly, Etienne

    2012-04-01

    Most viruses use the mRNA-cap dependent cellular translation machinery to translate their mRNAs into proteins. The addition of a cap structure at the 5' end of mRNA is therefore an essential step for the replication of many virus families. Additionally, the cap protects the viral RNA from degradation by cellular nucleases and prevents viral RNA recognition by innate immunity mechanisms. Viral RNAs acquire their cap structure either by using cellular capping enzymes, by stealing the cap of cellular mRNA in a process named "cap snatching", or using virus-encoded capping enzymes. Many viral enzymes involved in this process have recently been structurally and functionally characterized. These studies have revealed original cap synthesis mechanisms and pave the way towards the development of specific inhibitors bearing antiviral drug potential. © 2012 médecine/sciences – Inserm / SRMS.

  9. Ice caps on venus?

    PubMed

    Libby, W F

    1968-03-08

    The data on Venus obtained by Mariner V and Venera 4 are interpreted as evidence of giant polar ice caps holding the water that must have come out of the volcanoes with the observed carbon dioxide, on the assumption that Earth and Venus are of similar composition and volcanic history. The measurements by Venera 4 of the equatorial surface temperature indicate that the microwave readings were high, so that the polar ice caps may be allowed to exist in the face of the 10-centimeter readings of polar temperature. Life seems to be distinctly possible at the edges of the ice sheets.

  10. South Polar Cap

    NASA Technical Reports Server (NTRS)

    2005-01-01

    8 December 2005 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows landforms created by sublimation processes on the south polar residual cap of Mars. The bulk of the ice in the south polar residual cap is frozen carbon dioxide.

    Location near: 86.6oS, 342.2oW Image width: width: 3 km (1.9 mi) Illumination from: upper left Season: Southern Summer

  11. Commercialization Assistance Program (CAP)

    SciTech Connect

    Jenny C. Servo, Ph.D.

    2004-07-12

    In order to fulfill the objective of Small Business Innovation Research Program (SBIR), the Department of Energy funds an initiative referred to as the Commercialization Assistance Program (CAP). The over-arching purpose of the CAP is to facilitate transition of the SBIR-funded technology to Phase III defined as private sector investment or receipt of non-sbir dollars to further the commercialization of the technology. Phase III also includes increased sales. This report summarizes the stages involved in the implementation of the Commercialization Assistance Program, a program which has been most successful in fulfilling its objectives.

  12. South Polar Cap

    NASA Technical Reports Server (NTRS)

    2005-01-01

    8 December 2005 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows landforms created by sublimation processes on the south polar residual cap of Mars. The bulk of the ice in the south polar residual cap is frozen carbon dioxide.

    Location near: 86.6oS, 342.2oW Image width: width: 3 km (1.9 mi) Illumination from: upper left Season: Southern Summer

  13. Capping risk adjustment?

    PubMed

    Eugster, Patrick; Sennhauser, Michèle; Zweifel, Peter

    2010-07-01

    When premiums are community-rated, risk adjustment (RA) serves to mitigate competitive insurers' incentive to select favorable risks. However, unless fully prospective, it also undermines their incentives for efficiency. By capping its volume, one may try to counteract this tendency, exposing insurers to some financial risk. This in term runs counter the quest to refine the RA formula, which would increase RA volume. Specifically, the adjuster, "Hospitalization or living in a nursing home during the previous year" will be added in Switzerland starting 2012. This paper investigates how to minimize the opportunity cost of capping RA in terms of increased incentives for risk selection.

  14. The Crystal Structure of the PB2 Cap-binding Domain of Influenza B Virus Reveals a Novel Cap Recognition Mechanism*

    PubMed Central

    Liu, Yong; Yang, Yongfeng; Fan, Jialin; He, Ruina; Luo, Ming; Zheng, Xiaofeng

    2015-01-01

    The influenza RNA-dependent RNA polymerase is a core enzyme required for both transcription and replication of the virus RNA genome, making it a potential drug target for the influenza virus. To detect the feature of cap-dependent transcription of influenza B virus (FluB) polymerase, we determined the crystal structures of the wild-type FluB polymerase PB2 subunit cap-binding domain (PB2cap) with bound GDP and the mutant FluB Q325F PB2cap with bound m7GDP or GDP. These structures revealed that, distinct from influenza A virus (FluA) PB2cap, the guanine and ribose moieties of substrates invert in FluB PB2caps. Moreover, we characterized the substrate specificity and affinity of the PB2caps using isothermal titration calorimetry. FluB PB2cap has a weaker affinity for m7GDP than FluA PB2cap. Unlike FluA PB2cap that has a preference for m7GDP in comparison with GDP, FluB PB2cap shows an analogous affinity for both substrates. Replacement of FluB PB2 Glu325 by Phe, the corresponding residue of FluA PB2, increased the binding affinity of FluB PB2cap for m7GDP to a level approximate to that of FluA PB2cap and caused a significant higher affinity to GDP. This study indicated that FluB PB2cap has a unique cap recognition mechanism compared with FluA PB2cap, providing molecular insight into inhibitor design targeting FluB PB2cap. PMID:25691568

  15. A Method for Computing the Core Flow in Three-Dimensional Leading-Edge Vortices. Ph.D. Thesis - North Carolina State Univ.

    NASA Technical Reports Server (NTRS)

    Luckring, J. M.

    1985-01-01

    A theory is presented for calculating the flow in the core of a separation-induced leading-edge vortex. The method is based on matching inner and outer representations of the vortex. The inner model of the vortex is based on the quasicylindrical Navier-Stokes equations; the flow is assumed to be steady, axially symmetric, and incompressible and in addition, gradients in the radial direction are assumed to be much larger then gradients in the axial direction. The outer model is based on the three-dimensional free-vortex-sheet theory, a higher-order panel method which solves the Prandtl-Glauert equation including nonlinear boundary conditions pertinent to the concentrated vorticity representation of the leading edge vortex. The resultant flow is evaluated a posteriori for evidence of incipient vortex breakdown and the critical helix angle concept, in conjunction with an adverse longitudinal pressure gradient, is found to correlate well with the occurrence of vortex breakdown at the trailing edge of delta, arrow, and diamond wings.

  16. 4. CAP; SHOWS TRANSITIONAL FRAMING OF CAP ROOF WITH THREE ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    4. CAP; SHOWS TRANSITIONAL FRAMING OF CAP ROOF WITH THREE PAIR OF RAFTERS MORTISED INTO A BOSS; BRAKE WHEEL AND WINDSHAFT - Hook Windmill, North Main Street at Pantigo Road, East Hampton, Suffolk County, NY

  17. 3. CAP; CONICAL CAP HAS BOWED RAFTERS MORTISED INTO A ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    3. CAP; CONICAL CAP HAS BOWED RAFTERS MORTISED INTO A BOSS; ALSO SEEN ARE THE BRAKE WHEEL, WINDSHAFT AND TOP BEARING OF THE UPRIGHT SHAFT - Hayground Windmill, Windmill Lane, East Hampton, Suffolk County, NY

  18. Cradle Cap (For Parents)

    MedlinePlus

    ... cap will have skin that is a little red or itchy, and some might even have hair loss, though the hair usually grows back after ... parts of the body the rash is causing hair loss or becomes itchy the affected skin becomes firm and red, starts to drain fluid, or feels warm, which ...

  19. North Polar Cap

    NASA Technical Reports Server (NTRS)

    2004-01-01

    [figure removed for brevity, see original site]

    This week we will be looking at five examples of laminar wind flow on the north polar cap. On Earth, gravity-driven south polar cap winds are termed 'catabatic' winds. Catabatic winds begin over the smooth expanse of the cap interior due to temperature differences between the atmosphere and the surface. Once begun, the winds sweep outward along the surface of the polar cap toward the sea. As the polar surface slopes down toward sealevel, the wind speeds increase. Catabatic wind speeds in the Antartic can reach several hundreds of miles per hour.

    In the images of the Martian north polar cap we can see these same type of winds. Notice the streamers of dust moving downslope over the darker trough sides, these streamers show the laminar flow regime coming off the cap. Within the trough we see turbulent clouds of dust, kicked up at the trough base as the winds slow down and enter a chaotic flow regime.

    The horizontal lines in these images are due to framelet overlap and lighting conditions over the bright polar cap.

    Image information:VIS instrument. Latitude 86.5, longitude 57.4 East (302.6 West). 40 meter/pixel resolution.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is

  20. North Polar Cap

    NASA Technical Reports Server (NTRS)

    2004-01-01

    [figure removed for brevity, see original site]

    This week we will be looking at five examples of laminar wind flow on the north polar cap. On Earth, gravity-driven south polar cap winds are termed 'catabatic' winds. Catabatic winds begin over the smooth expanse of the cap interior due to temperature differences between the atmosphere and the surface. Once begun, the winds sweep outward along the surface of the polar cap toward the sea. As the polar surface slopes down toward sealevel, the wind speeds increase. Catabatic wind speeds in the Antartic can reach several hundreds of miles per hour.

    In the images of the Martian north polar cap we can see these same type of winds. Notice the streamers of dust moving downslope over the darker trough sides, these streamers show the laminar flow regime coming off the cap. Within the trough we see turbulent clouds of dust, kicked up at the trough base as the winds slow down and enter a chaotic flow regime.

    The horizontal lines in these images are due to framelet overlap and lighting conditions over the bright polar cap.

    Image information: VIS instrument. Latitude 86.5, Longitude 64.5 East (295.5 West). 40 meter/pixel resolution.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation

  1. North Polar Cap

    NASA Technical Reports Server (NTRS)

    2004-01-01

    [figure removed for brevity, see original site]

    This week we will be looking at five examples of laminar wind flow on the north polar cap. On Earth, gravity-driven south polar cap winds are termed 'catabatic' winds. Catabatic winds begin over the smooth expanse of the cap interior due to temperature differences between the atmosphere and the surface. Once begun, the winds sweep outward along the surface of the polar cap toward the sea. As the polar surface slopes down toward sealevel, the wind speeds increase. Catabatic wind speeds in the Antartic can reach several hundreds of miles per hour.

    In the images of the Martian north polar cap we can see these same type of winds. Notice the streamers of dust moving downslope over the darker trough sides, these streamers show the laminar flow regime coming off the cap. Within the trough we see turbulent clouds of dust, kicked up at the trough base as the winds slow down and enter a chaotic flow regime.

    The horizontal lines in these images are due to framelet overlap and lighting conditions over the bright polar cap.

    Image information: VIS instrument. Latitude 84.2, Longitude 57.4 East (302.6 West). 40 meter/pixel resolution.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation

  2. North Polar Cap

    NASA Technical Reports Server (NTRS)

    2004-01-01

    [figure removed for brevity, see original site]

    This week we will be looking at five examples of laminar wind flow on the north polar cap. On Earth, gravity-driven south polar cap winds are termed 'catabatic' winds. Catabatic winds begin over the smooth expanse of the cap interior due to temperature differences between the atmosphere and the surface. Once begun, the winds sweep outward along the surface of the polar cap toward the sea. As the polar surface slopes down toward sealevel, the wind speeds increase. Catabatic wind speeds in the Antartic can reach several hundreds of miles per hour.

    In the images of the Martian north polar cap we can see these same type of winds. Notice the streamers of dust moving downslope over the darker trough sides, these streamers show the laminar flow regime coming off the cap. Within the trough we see turbulent clouds of dust, kicked up at the trough base as the winds slow down and enter a chaotic flow regime.

    The horizontal lines in these images are due to framelet overlap and lighting conditions over the bright polar cap.

    Image information: VIS instrument. Latitude 84.3, Longitude 314.4 East (45.6 West). 40 meter/pixel resolution.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation

  3. North Polar Cap

    NASA Technical Reports Server (NTRS)

    2004-01-01

    [figure removed for brevity, see original site]

    This week we will be looking at five examples of laminar wind flow on the north polar cap. On Earth, gravity-driven south polar cap winds are termed 'catabatic' winds. Catabatic winds begin over the smooth expanse of the cap interior due to temperature differences between the atmosphere and the surface. Once begun, the winds sweep outward along the surface of the polar cap toward the sea. As the polar surface slopes down toward sealevel, the wind speeds increase. Catabatic wind speeds in the Antartic can reach several hundreds of miles per hour.

    In the images of the Martian north polar cap we can see these same type of winds. Notice the streamers of dust moving downslope over the darker trough sides, these streamers show the laminar flow regime coming off the cap. Within the trough we see turbulent clouds of dust, kicked up at the trough base as the winds slow down and enter a chaotic flow regime.

    The horizontal lines in these images are due to framelet overlap and lighting conditions over the bright polar cap.

    Image information: VIS instrument. Latitude 86.5, Longitude 64.5 East (295.5 West). 40 meter/pixel resolution.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation

  4. North Polar Cap

    NASA Technical Reports Server (NTRS)

    2004-01-01

    [figure removed for brevity, see original site]

    This week we will be looking at five examples of laminar wind flow on the north polar cap. On Earth, gravity-driven south polar cap winds are termed 'catabatic' winds. Catabatic winds begin over the smooth expanse of the cap interior due to temperature differences between the atmosphere and the surface. Once begun, the winds sweep outward along the surface of the polar cap toward the sea. As the polar surface slopes down toward sealevel, the wind speeds increase. Catabatic wind speeds in the Antartic can reach several hundreds of miles per hour.

    In the images of the Martian north polar cap we can see these same type of winds. Notice the streamers of dust moving downslope over the darker trough sides, these streamers show the laminar flow regime coming off the cap. Within the trough we see turbulent clouds of dust, kicked up at the trough base as the winds slow down and enter a chaotic flow regime.

    The horizontal lines in these images are due to framelet overlap and lighting conditions over the bright polar cap.

    Image information: VIS instrument. Latitude 84.3, Longitude 314.4 East (45.6 West). 40 meter/pixel resolution.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation

  5. North Polar Cap

    NASA Technical Reports Server (NTRS)

    2004-01-01

    [figure removed for brevity, see original site]

    This week we will be looking at five examples of laminar wind flow on the north polar cap. On Earth, gravity-driven south polar cap winds are termed 'catabatic' winds. Catabatic winds begin over the smooth expanse of the cap interior due to temperature differences between the atmosphere and the surface. Once begun, the winds sweep outward along the surface of the polar cap toward the sea. As the polar surface slopes down toward sealevel, the wind speeds increase. Catabatic wind speeds in the Antartic can reach several hundreds of miles per hour.

    In the images of the Martian north polar cap we can see these same type of winds. Notice the streamers of dust moving downslope over the darker trough sides, these streamers show the laminar flow regime coming off the cap. Within the trough we see turbulent clouds of dust, kicked up at the trough base as the winds slow down and enter a chaotic flow regime.

    The horizontal lines in these images are due to framelet overlap and lighting conditions over the bright polar cap.

    Image information: VIS instrument. Latitude 84.2, Longitude 57.4 East (302.6 West). 40 meter/pixel resolution.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation

  6. North Polar Cap

    NASA Technical Reports Server (NTRS)

    2004-01-01

    [figure removed for brevity, see original site]

    This week we will be looking at five examples of laminar wind flow on the north polar cap. On Earth, gravity-driven south polar cap winds are termed 'catabatic' winds. Catabatic winds begin over the smooth expanse of the cap interior due to temperature differences between the atmosphere and the surface. Once begun, the winds sweep outward along the surface of the polar cap toward the sea. As the polar surface slopes down toward sealevel, the wind speeds increase. Catabatic wind speeds in the Antartic can reach several hundreds of miles per hour.

    In the images of the Martian north polar cap we can see these same type of winds. Notice the streamers of dust moving downslope over the darker trough sides, these streamers show the laminar flow regime coming off the cap. Within the trough we see turbulent clouds of dust, kicked up at the trough base as the winds slow down and enter a chaotic flow regime.

    The horizontal lines in these images are due to framelet overlap and lighting conditions over the bright polar cap.

    Image information:VIS instrument. Latitude 86.5, longitude 57.4 East (302.6 West). 40 meter/pixel resolution.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is

  7. Lead isotopic signatures in Antarctic marine sediment cores: a comparison between 1M HCl partial extraction and HF total digestion pre-treatments for discerning anthropogenic inputs.

    PubMed

    Townsend, A T; Snape, I; Palmer, A S; Seen, A J

    2009-12-20

    Sensitive analytical techniques are typically required when dealing with samples from Antarctica as even low concentrations of contaminants can have detrimental environmental effects. Magnetic Sector ICP-MS is an ideal technique for environmental assessment as it offers high sensitivity, multi-element capability and the opportunity to determine isotope ratios. Here we consider the Pb isotope record of five marine sediment cores collected from three sites in the Windmill Islands area of East Antarctica: Brown Bay adjacent to the current Australian station Casey, Wilkes near the abandoned US/Australian Station and McGrady Cove lying midway between the two. Two sediment pre-treatment approaches were considered, namely partial extraction with 1M HCl and total dissolution involving HF. Lead isotope ratio measurements made following sediment partial extraction provided a more sensitive indication of Pb contamination than either Pb concentrations alone (irrespective of sample pre-treatment method) or isotope ratios made after HF digestion, offering greater opportunity for discrimination between impacted and natural/geogenic samples and sites. Over 90% of the easily extractable Pb from sediments near Casey was anthropogenic in origin, consisting of Pb from major Australian deposits. At Wilkes impact from discarded batteries with a unique isotopic signature was found to be a key source of Pb contamination to the marine environment with ~70-80% of Pb being anthropogenic in origin. The country and source of origin of these batteries remain unknown. Little evidence was found suggesting contamination at Wilkes by Pb originating from the major US source, Missouri. No definitive assessment could be made regarding Pb impact at McGrady Cove as the collected sediment core was of insufficient depth. Although Pb isotope ratio signatures may indicate anthropogenic input, spatial concentration gradients at nearby Brown Bay suggest contamination at McGrady Cove is unlikely. We recommend

  8. Lack of parvalbumin in mice leads to behavioral deficits relevant to all human autism core symptoms and related neural morphofunctional abnormalities

    PubMed Central

    Wöhr, M; Orduz, D; Gregory, P; Moreno, H; Khan, U; Vörckel, K J; Wolfer, D P; Welzl, H; Gall, D; Schiffmann, S N; Schwaller, B

    2015-01-01

    Gene mutations and gene copy number variants are associated with autism spectrum disorders (ASDs). Affected gene products are often part of signaling networks implicated in synapse formation and/or function leading to alterations in the excitation/inhibition (E/I) balance. Although the network of parvalbumin (PV)-expressing interneurons has gained particular attention in ASD, little is known on PV's putative role with respect to ASD. Genetic mouse models represent powerful translational tools for studying the role of genetic and neurobiological factors underlying ASD. Here, we report that PV knockout mice (PV−/−) display behavioral phenotypes with relevance to all three core symptoms present in human ASD patients: abnormal reciprocal social interactions, impairments in communication and repetitive and stereotyped patterns of behavior. PV-depleted mice also showed several signs of ASD-associated comorbidities, such as reduced pain sensitivity and startle responses yet increased seizure susceptibility, whereas no evidence for behavioral phenotypes with relevance to anxiety, depression and schizophrenia was obtained. Reduced social interactions and communication were also observed in heterozygous (PV+/−) mice characterized by lower PV expression levels, indicating that merely a decrease in PV levels might be sufficient to elicit core ASD-like deficits. Structural magnetic resonance imaging measurements in PV−/− and PV+/− mice further revealed ASD-associated developmental neuroanatomical changes, including transient cortical hypertrophy and cerebellar hypoplasia. Electrophysiological experiments finally demonstrated that the E/I balance in these mice is altered by modification of both inhibitory and excitatory synaptic transmission. On the basis of the reported changes in PV expression patterns in several, mostly genetic rodent models of ASD, we propose that in these models downregulation of PV might represent one of the points of convergence, thus

  9. Synextensional magmatism leading to crustal flow in the Albion-Raft River-Grouse Creek metamorphic core complex, northeastern Basin and Range

    NASA Astrophysics Data System (ADS)

    Konstantinou, Alexandros; Strickland, Ariel; Miller, Elizabeth; Vervoort, Jeffrey; Fisher, Christopher M.; Wooden, Joseph; Valley, John

    2013-09-01

    study addresses the origin of granitic magmas in the Albion-Raft River-Grouse Creek (ARG) metamorphic core complex and environs and how these inform us about the deep crustal processes leading to crustal flow and the formation of the ARG. SHRIMP-RG U-Pb zircon ages, whole-rock geochemical data (major and trace element data, as well as Sr and Nd isotopes), and zircon geochemistry (in situ O-isotope, Hf-isotope, and trace element compositions) from Eocene to Oligocene magmas now exposed at three structural levels of the ARG show that the 41-32 Ma Emigrant Pass and the 32-25 Ma Cassia plutonic complexes have a common origin, sharing a deep crustal "hot zone" that remained above solidus temperatures for at least 16 Myr. This magmatism is part of the protracted magmatism that swept southward across the western U.S. between ˜42 and 21 Ma, inferred to be the result of foundering of the shallow Farallon slab. Isotopic modeling of geochemical data from these magmas suggests that between 41 and 32 Ma, the influx of mantle-derived basalt into the lower crust triggered large-scale hybrid magmatism generating calc-alkaline magmas that erupted and intruded the upper crust and significantly weakened the lower and middle crust. Between 32 and 25 Ma, this "hot zone" incorporated large amounts of continental crustal melts, resulting in greater mobility of the lower and middle crust, driving middle crustal flow and the formation of granitic plutons that rose to shallower levels of the crust forming the granite-cored gneiss domes of the ARG.

  10. Characterization of Contaminant Migration Potential Through In-Place Sediment Caps

    DTIC Science & Technology

    2009-04-01

    3-6. Opening the Aluminum Core Tube for Sediment Core Processing Using a Circular Saw...commenced using a contracted vessel with vibracoring capabilities (Figure 3-4). Cores of a 3-inch diameter were collected using thick-walled aluminum ...cap/pull cap Drive rod (1/2” dia. tempered steel rod) Drive rod (1/2” dia. tempered steel rod) 2 ft 3 ft Conductivity probe Increments for profile

  11. Characterization of fracture behavior of human atherosclerotic fibrous caps using a miniature single edge notched tensile test.

    PubMed

    Davis, Lindsey A; Stewart, Samantha E; Carsten, Christopher G; Snyder, Bruce A; Sutton, Michael A; Lessner, Susan M

    2016-10-01

    One well-established cause of ischemic stroke is atherosclerotic plaque rupture in the carotid artery. Rupture occurs when a tear in the fibrous cap exposes highly thrombogenic material in the lipid core. Though some fibrous cap material properties have been measured, such as ultimate tensile strength and stress-strain responses, there has been very little, if any, data published regarding the fracture behavior of atherosclerotic fibrous caps. This study aims to characterize the qualitative and quantitative fracture behavior of human atherosclerotic plaque tissue obtained from carotid endarterectomy samples using two different metrics. Uniaxial tensile experiments along with miniature single edge notched tensile (MSENT) experiments were performed on strips of isolated fibrous cap. Crack tip opening displacement (CTOD) and stress in the un-cracked segment (UCS) were measured at failure in fibrous cap MSENT specimens subjected to uniaxial tensile loading. Both CTOD and the degree of crack blunting, measured as the radius of curvature of the crack tip, increased as tearing propagated through the tissue. Higher initial stress in the UCS is significantly correlated with higher collagen content and lower macrophage content in the fibrous cap (ρ=0.77, P=0.009; ρ=-0.64, P=0.047; respectively). Trends in the data show that higher CTOD is inversely related to collagen content, though the sample size in this study is insufficient to statistically substantiate this relationship. To the authors' knowledge, this is the pioneering study examining the fracture behavior of fibrous caps and the first use of the CTOD metric in vascular tissue. A tear in the fibrous cap of atherosclerotic plaque can lead to ischemic stroke or myocardial infarction. While there is some information in the literature regarding quantitative measures of fibrous cap failure, there is little information regarding the behavior of the tissue during failure. This study examines the failure behavior of fibrous

  12. Designing Smart Charter School Caps

    ERIC Educational Resources Information Center

    Dillon, Erin

    2010-01-01

    In 2007, Andrew J. Rotherham proposed a new approach to the contentious issue of charter school caps, the statutory limits on charter school growth in place in several states. Rotherham's proposal, termed "smart charter school caps," called for quality sensitive caps that allow the expansion of high-performing charter schools while also…

  13. The size of the EB cap determines instantaneous microtubule stability

    PubMed Central

    Duellberg, Christian; Cade, Nicholas I; Holmes, David; Surrey, Thomas

    2016-01-01

    The function of microtubules relies on their ability to switch between phases of growth and shrinkage. A nucleotide-dependent stabilising cap at microtubule ends is thought to be lost before this switch can occur; however, the nature and size of this protective cap are unknown. Using a microfluidics-assisted multi-colour TIRF microscopy assay with close-to-nm and sub-second precision, we measured the sizes of the stabilizing cap of individual microtubules. We find that the protective caps are formed by the extended binding regions of EB proteins. Cap lengths vary considerably and longer caps are more stable. Nevertheless, the trigger of instability lies in a short region at the end of the cap, as a quantitative model of cap stability demonstrates. Our study establishes the spatial and kinetic characteristics of the protective cap and provides an insight into the molecular mechanism by which its loss leads to the switch from microtubule growth to shrinkage. DOI: http://dx.doi.org/10.7554/eLife.13470.001 PMID:27050486

  14. Biochemical principles and inhibitors to interfere with viral capping pathways.

    PubMed

    Decroly, Etienne; Canard, Bruno

    2017-06-01

    Messenger RNAs are decorated by a cap structure, which is essential for their translation into proteins. Many viruses have developed strategies in order to cap their mRNAs. The cap is either synthetized by a subset of viral or cellular enzymes, or stolen from capped cellular mRNAs by viral endonucleases ('cap-snatching'). Reverse genetic studies provide evidence that inhibition of viral enzymes belonging to the capping pathway leads to inhibition of virus replication. The replication defect results from reduced protein synthesis as well as from detection of incompletely capped RNAs by cellular innate immunity sensors. Thus, it is now admitted that capping enzymes are validated antiviral targets, as their inhibition will support an antiviral response in addition to the attenuation of viral mRNA translation. In this review, we describe the different viral enzymes involved in mRNA capping together with relevant inhibitors, and their biochemical features useful in inhibitor discovery. Copyright © 2017 Elsevier B.V. All rights reserved.

  15. Summer South Polar Cap

    NASA Technical Reports Server (NTRS)

    2004-01-01

    13 April 2004 The martian south polar residual ice cap is composed mainly of frozen carbon dioxide. Each summer, a little bit of this carbon dioxide sublimes away. Pits grow larger, and mesas get smaller, as this process continues from year to year. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a view of a small portion of the south polar cap as it appeared in mid-summer in January 2004. The dark areas may be places where the frozen carbon dioxide contains impurities, such as dust, or places where sublimation of ice has roughened the surface so that it appears darker because of small shadows cast by irregularities in the roughened surface. The image is located near 86.9oS, 7.6oW. The image covers an area about 3 km (1.9 mi) across. Sunlight illuminates the scene from the upper left.

  16. Performance of blasting caps

    NASA Technical Reports Server (NTRS)

    Bement, Laurence J. (Inventor); Schimmel, Morry L. (Inventor); Perry, Ronnie B. (Inventor)

    1993-01-01

    Common blasting caps are made from an aluminum shell in the form of a tube which is closed at both ends. One end, which is called the output end, terminates in a principal side or face, and contains a detonating agent which communicates with a means for igniting the detonating agent. The improvement of the present invention is a flat, steel foil bonded to the face in a position which is aligned perpendicularly to the longitudinal axis of the tube.

  17. South Polar Cap

    NASA Technical Reports Server (NTRS)

    2005-01-01

    17 March 2005 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows mesas and pits formed by sublimation of carbon dioxide of the south polar cap.

    Location near: 85.8oS, 351.5oW Image width: 2 km (1.2 mi) Illumination from: upper left Season: Southern Summer

  18. Schaefer's "family cap".

    PubMed

    1994-02-14

    Criticism was directed to Maryland Governor William Donald Shaefer's proposal to put family caps on welfare payments to recipients. The idea was to stop automatic increases in welfare payments if a recipient has an additional child. The objection was that 77%, or the bulk of welfare recipients, have only one or two children, and there is little, if any, evidence that welfare caps influence childbearing. The consequences of such reform would be the penalization of children. The political reality is that symbolism has become more important than facts. Putting a cap on welfare may make people feel better about welfare, and may show fairness to working people who don't get raises when their family size increases, but there are other implications. The messages to welfare recipients to stop having children, but not providing the means to do so, is hypocritical. Medicaid abortions were restricted in 1978 by politicians, but provision for better access to contraceptives was never promoted or achieved. Circumstances limit opportunities. The quality of care in public health clinics is abysmal: long lines and overcrowding, and inadequate proximity to welfare recipients' housing. Transportation, particularly in rural areas, is an impediment to access. It is estimated that only 60% of women eligible for government-funded contraception have access. A sign of serious welfare reform will be budget appropriations for day care, job training, and other reform programs.

  19. North Polar Ice Cap

    NASA Technical Reports Server (NTRS)

    1997-01-01

    North polar ice cap of Mars, as seen during mid summer in the northern hemisphere. The reddish areas consist of eolian dust, bright white areas consist of a mixture of water ice and dust, and the dark blue areas consist of sand dunes forming a huge 'collar' around the polar ice cap. (The colors have been enhanced with a decorrelation stretch to better show the color variability.) Shown here is an oblique view of the polar region, as seen with the Viking 1 spacecraft orbiting Mars over latitude 39 degrees north. The spiral bands consist of valleys which form by a combination of the Coriolis forces, wind erosion, and differential sublimation and condensation. In high-resolution images the polar caps are seen to consist of thick sequences of layered deposits, suggesting that cyclical climate changes have occurred on Mars. Cyclical climate changes are readily explained by quasi-periodic changes in the amount and distribution of solar heating resulting from perturbations in orbital and axial elements. Variations in the Earth's orbit have also been linked to the terrestrial climate changes during the ice ages.

  20. The polar cap environment of outflowing O(+)

    NASA Technical Reports Server (NTRS)

    Horwitz, J. L.; Pollock, C. J.; Moore, T. E.; Peterson, W. K.; Burch, J. L.; Winningham, J. D.; Craven, J. D.; Frank, L. A.; Persoon, A.

    1992-01-01

    The properties of the core (0-50 eV) and 'energetic' (0-1 keV) ions, plasma waves, and auroral images obtained from Dynamics Explorer 1 (DE-1) and those of electrons, obtained from DE-2, are examined in the context of the polar cap environment. Results indicate the presence of two populations: high-speed (10-30 eV, or higher, streaming energies) polar beams and low-speed (generally less than 10-eV streaming energies) streams. The high-speed polar beams show an auroral connection (i.e., they are observed on or near the field lines threading auroral arcs), while the low-speed streams are on or near the field lines threading the dark polar cap and may be converted from the cleft ion fountain. Compared to the high-speed streams, the low-speed streams are significantly more stable with respect to energy and flux.

  1. Core-Shell Structured Magnetic Ternary Nanocubes

    SciTech Connect

    Wang, Lingyan; Wang, Xin; Luo, Jin; Wanjala, Bridgid N.; Wang, Chong M.; Chernova, Natalya; Engelhard, Mark H.; Liu, Yao; Bae, In-Tae; Zhong, Chuan-Jian

    2010-12-01

    While transition metal-doped ferrite nanoparticles constitute an important class of soft magnetic nanomaterials with spinel structures, the ability to control the shape and composition would enable a wide range of applications in homogeneous or heterogeneous reactions such as catalysis and magnetic separation of biomolecules. This report describes novel findings of an investigation of core-shell structured MnZn ferrite nanocubes synthesized in organic solvents by manipulating the reaction temperature and capping agent composition in the absence of the conventionally-used reducing agents. The core-shell structure of the highly-monodispersed nanocubes (~20 nm) are shown to consist of an Fe3O4 core and an (Mn0.5Zn0.5)(Fe0.9, Mn1.1)O4 shell. In comparison with Fe3O4 and other binary ferrite nanoparticles, the core-shell structured nanocubes were shown to display magnetic properties regulated by a combination of the core-shell composition, leading to a higher coercivity (~350 Oe) and field-cool/zero-field-cool characteristics drastically different from many regular MnZn ferrite nanoparticles. The findings are discussed in terms of the unique core-shell composition, the understanding of which has important implication to the exploration of this class of soft magnetic nanomaterials in many potential applications such as magnetic resonance imaging, fuel cells, and batteries.

  2. Saltstone Clean Cap Formulation

    SciTech Connect

    Langton, C

    2005-04-22

    The current operation strategy for using Saltstone Vault 4 to receive 0.2 Ci/gallon salt solution waste involves pouring a clean grout layer over the radioactive grout prior to initiating pour into another cell. This will minimize the radiating surface area and reduce the dose rate at the vault and surrounding area. The Clean Cap will be used to shield about four feet of Saltstone poured into a Z-Area vault cell prior to moving to another cell. The minimum thickness of the Clean Cap layer will be determined by the cesium concentration and resulting dose levels and it is expected to be about one foot thick based on current calculations for 0.1 Ci Saltstone that is produced in the Saltstone process by stabilization of 0.2 Ci salt solution. This report documents experiments performed to identify a formulation for the Clean Cap. Thermal transient calculations, adiabatic temperature rise measurements, pour height, time between pour calculations and shielding calculations were beyond the scope and time limitations of this study. However, data required for shielding calculations (composition and specific gravity) are provided for shielding calculations. The approach used to design a Clean Cap formulation was to produce a slurry from the reference premix (10/45/45 weight percent cement/slag/fly ash) and domestic water that resembled as closely as possible the properties of the Saltstone slurry. In addition, options were investigated that may offer advantages such as less bleed water and less heat generation. The options with less bleed water required addition of dispersants. The options with lower heat contained more fly ash and less slag. A mix containing 10/45/45 weight percent cement/slag/fly ash with a water to premix ratio of 0.60 is recommended for the Clean Cap. Although this mix may generate more than 3 volume percent standing water (bleed water), it has rheological, mixing and flow properties that are similar to previously processed Saltstone. The recommended

  3. The Influence of Aleutian Low Intensity on Trans-Pacific Lead Pollution Transport as Recorded in Two Saint Elias Ice Cores

    NASA Astrophysics Data System (ADS)

    Osterberg, E. C.; Kreutz, K. J.; Mayewski, P. A.; Fisher, D. A.; Wake, C. P.; Handley, M.

    2009-12-01

    The Aleutian Low (ALOW) is a semi-permanent low pressure center that dominates the wintertime climate of the North Pacific, and is an integral component of major ocean-atmosphere climate oscillations including the Pacific Decadal Oscillation and the extra-tropical response to the El Niño-Southern Oscillation. Previous research has suggested that the trans-Pacific transport of dust and pollution from Asia to the North Pacific is enhanced under conditions with a strong ALOW and strong Pacific High, increasing average mid-latitude westerly wind velocities. Here we investigate the influence of annual ALOW intensity fluctuations on the trans-Pacific transport of lead (Pb) pollution as recorded in ice cores collected from the Mt. Logan summit plateau (5300 m asl) and Eclipse Icefield (3017 m asl). These two ice core sites are well suited to investigate vertical gradients in climate and pollution because they are situated <50 km apart with over 2000 m in elevation difference. While Pb concentration and stable isotope 208Pb/207Pb and 206Pb/207Pb data confirm that both the Mt. Logan summit and Eclipse Icefield receive significant trans-Pacific Pb pollution, the Mt. Logan summit Pb concentration is positively correlated with ALOW strength (r=0.40, p<0.001; 1900-1998 A.D.), while Eclipse Pb concentration is negatively correlated with ALOW strength (r=-0.57, p<0.001; 1971-2000 A.D.). We hypothesize that this opposite correlation with ALOW strength is due to the relationship between ALOW intensity and mean winter cyclone longitude. Winter cyclones migrate further to the east during strong ALOW winters, frequently becoming occluded along the Gulf of Alaska coastline immediately offshore from Mt. Logan and Eclipse. Occluded cyclones are stratified by the warm front, with lower elevation sites like Eclipse situated in a cold-air zone sourced by a relatively clean local airmass from the Gulf of Alaska, whereas higher elevation sites like the Mt. Logan summit plateau are situated

  4. The nature of the residual Martian polar caps

    NASA Technical Reports Server (NTRS)

    Briggs, G. A.

    1974-01-01

    A model of the behavior of the Martian polar caps is described which incorporates the heating effects of the atmosphere, as well as insolation and conduction. This model is used to try to match the observed regression curves of the polar caps, and it predicts that all the seasonally condensed CO2 will be lost by around the summer solstice. The implication is that the residual caps are composed of water ice which, it is found by further modeling, should be stable during the Martian summers. However, it is also argued that this model may be too simplistic, and that the effects of wind in redistributing the seasonal condensate may lead to sufficient thicknesses of CO2 in the central polar region to allow the year-long existence of CO2 without significantly changing the retreat characteristics of the cap, and it is, therefore, concluded that at the present, the nature of the residual caps cannot be reliably determined.

  5. The effects of plaque morphology and material properties on peak cap stress in human coronary arteries.

    PubMed

    Akyildiz, Ali C; Speelman, Lambert; Nieuwstadt, Harm A; van Brummelen, Harald; Virmani, Renu; van der Lugt, Aad; van der Steen, Anton F W; Wentzel, Jolanda J; Gijsen, Frank J H

    2016-01-01

    Heart attacks are often caused by rupture of caps of atherosclerotic plaques in coronary arteries. Cap rupture occurs when cap stress exceeds cap strength. We investigated the effects of plaque morphology and material properties on cap stress. Histological data from 77 coronary lesions were obtained and segmented. In these patient-specific cross sections, peak cap stresses were computed by using finite element analyses. The finite element analyses were 2D, assumed isotropic material behavior, and ignored residual stresses. To represent the wide spread in material properties, we applied soft and stiff material models for the intima. Measures of geometric plaque features for all lesions were determined and their relations to peak cap stress were examined using regression analyses. Patient-specific geometrical plaque features greatly influence peak cap stresses. Especially, local irregularities in lumen and necrotic core shape as well as a thin intima layer near the shoulder of the plaque induce local stress maxima. For stiff models, cap stress increased with decreasing cap thickness and increasing lumen radius (R = 0.79). For soft models, this relationship changed: increasing lumen radius and increasing lumen curvature were associated with increased cap stress (R = 0.66). The results of this study imply that not only accurate assessment of plaque geometry, but also of intima properties is essential for cap stress analyses in atherosclerotic plaques in human coronary arteries.

  6. Global Core Plasma Model

    NASA Technical Reports Server (NTRS)

    Gallagher, Dennis L.; Craven, P. D.; Comfort, R. H.

    1999-01-01

    Abstract. The Global Core Plasma Model (GCPM) provides, empirically derived, core plasma density as a function of geomagnetic and solar conditions throughout the inner magnetosphere. It is continuous in value and gradient and is composed of separate models for the ionosphere, the plasmasphere, the plasmapause, the trough, and the polar cap. The relative composition of plasmaspheric H+, He+, and O+ is included in the GCPM. A blunt plasmaspheric bulge and rotation of the bulge with changing geomagnetic conditions is included. The GCPM is an amalgam of density models, intended to serve as a framework for continued improvement as new measurements become available and are used to characterize core plasma density, composition, and temperature.

  7. Global Core Plasma Model

    NASA Technical Reports Server (NTRS)

    Gallagher, Dennis L.; Craven, P. D.; Comfort, R. H.

    1999-01-01

    Abstract. The Global Core Plasma Model (GCPM) provides, empirically derived, core plasma density as a function of geomagnetic and solar conditions throughout the inner magnetosphere. It is continuous in value and gradient and is composed of separate models for the ionosphere, the plasmasphere, the plasmapause, the trough, and the polar cap. The relative composition of plasmaspheric H+, He+, and O+ is included in the GCPM. A blunt plasmaspheric bulge and rotation of the bulge with changing geomagnetic conditions is included. The GCPM is an amalgam of density models, intended to serve as a framework for continued improvement as new measurements become available and are used to characterize core plasma density, composition, and temperature.

  8. Effect of swim cap model on passive drag.

    PubMed

    Gatta, Giorgio; Zamparo, Paola; Cortesi, Matteo

    2013-10-01

    Hydrodynamics plays an important role in swimming because even small decreases in a swimmer's drag can lead to performance improvements. During the gliding phases of a race, the head of a swimmer is an important point of impact with the fluid, and the swim cap, even if it covers only a small portion of the swimmer's body, can have an influence on drag. The purpose of this study was to investigate the effects on passive drag (Dp) of wearing 3 different types of swim caps (LSC: a lycra cap; CSC: a silicone cap; HSC: a silicone helmet cap without seams). Sixteen swimmers were tested at 3 velocities (1.5, 1.7, 1.9 m·s), and the Dp measurements were repeated at each condition 5 times. A statistical analysis revealed significant differences in drag (p < 0.01) among caps: Dp is 5-6.5% lower for HSC than for CSC at all speeds and 6% lower in HSC than CSC at 1.9 m·s. No differences in Dp were observed between LSC and CSC at all speeds. Thus, the differences in Dp are based on the type of material (lycra vs. silicone) and on the presence/lack of seams: the HSC swim cap is the most rigid, the most adherent to the swimmer's head, and does not allow the formation of wrinkles compared with the other 2 investigated swim caps. Therefore, the following conclusions can be made: (a) swimmers should take care when selecting their swim cap if they want to improve the fluid dynamics at the "leading edge" of their body and (b) because Dp is affected by the swim cap model, care should be taken when comparing data from different studies, especially at faster investigated speeds.

  9. Vinyl capped addition polyimides

    NASA Technical Reports Server (NTRS)

    Vannucci, Raymond D. (Inventor); Malarik, Diane C. (Inventor); Delvigs, Peter (Inventor)

    1990-01-01

    Polyimide resins having improved thermo-oxidative stability are provided having aromatic vinyl end-caps. The polyimides are prepared by the reaction of a mixture of monomers comprising (1) a diamine, (2) an ester of tetracarboxylic acid and (3) an aromatic vinyl compound in a molar ratio of 1:2:3 of n: (n + 1):2 when the aromatic vinyl compound contains nitrogen and in a ratio of (n + 1):n:2 when the aromatic vinyl compound does not contain nitrogen, wherein n ranges from about 5 to about 20.

  10. Polar Cap Retreat

    NASA Technical Reports Server (NTRS)

    2004-01-01

    13 August 2004 This red wide angle Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a view of the retreating seasonal south polar cap in the most recent spring in late 2003. Bright areas are covered with frost, dark areas are those from which the solid carbon dioxide has sublimed away. The center of this image is located near 76.5oS, 28.2oW. The scene is large; it covers an area about 250 km (155 mi) across. The scene is illuminated by sunlight from the upper left.

  11. Floating glacial ice caps in the arctic ocean.

    PubMed

    Broecker, W S

    1975-06-13

    Two arguments are presented, one in favor of the existence of thicker ice in the Arctic Ocean during glacial time, and the other in favor of a full-fledged Arctic ice cap. The first is based on the Greenland air temperature record obtained from isotopic studies of the Camp Century ice core. The second is based on the oxygen isotope record of benthic foraminifera from a deep Pacific Ocean core.

  12. Pits in Polar Cap

    NASA Technical Reports Server (NTRS)

    2006-01-01

    This full-frame image from the High Resolution Imaging Science Experiment camera on NASA's Mars Reconnaissance Orbiter shows faults and pits in Mars' north polar residual cap that have not been previously recognized.

    The faults and depressions between them are similar to features seen on Earth where the crust is being pulled apart. Such tectonic extension must have occurred very recently because the north polar residual cap is very young, as indicated by the paucity of impact craters on its surface. Alternatively, the faults and pits may be caused by collapse due to removal of material beneath the surface. The pits are aligned along the faults, either because material has drained into the subsurface along the faults or because gas has escaped from the subsurface through them.

    NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Mars Reconnaissance Orbiter for NASA's Science Mission Directorate, Washington. Lockheed Martin Space Systems, Denver, is the prime contractor for the project and built the spacecraft. The High Resolution Imaging Science Experiment is operated by the University of Arizona, Tucson, and the instrument was built by Ball Aerospace and Technology Corp., Boulder, Colo.

  13. South Polar Ice Cap

    NASA Technical Reports Server (NTRS)

    2003-01-01

    MGS MOC Release No. MOC2-337, 21 April 2003

    This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows the 'swiss cheese' pattern of frozen carbon dioxide on the south polar residual cap. Observation of these materials over two Mars years has revealed that the scarps that bound the mesas and small buttes are retreating-the carbon dioxide ice is subliming away-at a rate of about 3 meters (3 yards) per Mars year in some places. The picture covers an area about 900 m (about 900 yards) wide near 87.1oS, 93.7oW. Sunlight illuminates the scene from the upper left.

  14. Polar Cap Pits

    NASA Technical Reports Server (NTRS)

    2005-01-01

    17 August 2005 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows kidney bean-shaped pits, and other pits, formed by erosion in a landscape of frozen carbon dioxide. This images shows one of about a dozen different patterns that are common in various locations across the martian south polar residual cap, an area that has been receiving intense scrutiny by the MGS MOC this year, because it is visible on every orbit and in daylight for most of 2005.

    Location near: 86.9oS, 6.9oW Image width: width: 3 km (1.9 mi) Illumination from: upper left Season: Southern Spring

  15. Polar Cap Pits

    NASA Technical Reports Server (NTRS)

    2005-01-01

    17 August 2005 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows kidney bean-shaped pits, and other pits, formed by erosion in a landscape of frozen carbon dioxide. This images shows one of about a dozen different patterns that are common in various locations across the martian south polar residual cap, an area that has been receiving intense scrutiny by the MGS MOC this year, because it is visible on every orbit and in daylight for most of 2005.

    Location near: 86.9oS, 6.9oW Image width: width: 3 km (1.9 mi) Illumination from: upper left Season: Southern Spring

  16. Development of Gasless Pyrotechnic Cap

    DTIC Science & Technology

    1980-05-01

    beam cathode ray oscillo- scope. The caps were ignited by removing the safety pin . This also triggered the oscilloscope. The change in pressure inside...sensitivity. STRIKER SAFETY PIN PERCUSSION CAP FIXED VOLUME / ;PRESSURE TRANSDUCER TO C.R.O. FIG. 8 - Device used to determine pressure time

  17. Myofibril growth during cardiac hypertrophy is regulated through dual phosphorylation and acetylation of the actin capping protein CapZ.

    PubMed

    Lin, Ying-Hsi; Warren, Chad M; Li, Jieli; McKinsey, Timothy A; Russell, Brenda

    2016-08-01

    The mechanotransduction signaling pathways initiated in heart muscle by increased mechanical loading are known to lead to long-term transcriptional changes and hypertrophy, but the rapid events for adaptation at the sarcomeric level are not fully understood. The goal of this study was to test the hypothesis that actin filament assembly during cardiomyocyte growth is regulated by post-translational modifications (PTMs) of CapZβ1. In rapidly hypertrophying neonatal rat ventricular myocytes (NRVMs) stimulated by phenylephrine (PE), two-dimensional gel electrophoresis (2DGE) of CapZβ1 revealed a shift toward more negative charge. Consistent with this, mass spectrometry identified CapZβ1 phosphorylation on serine-204 and acetylation on lysine-199, two residues which are near the actin binding surface of CapZβ1. Ectopic expression of dominant negative PKCɛ (dnPKCɛ) in NRVMs blunted the PE-induced increase in CapZ dynamics, as evidenced by the kinetic constant (Kfrap) of fluorescence recovery after photobleaching (FRAP), and concomitantly reduced phosphorylation and acetylation of CapZβ1. Furthermore, inhibition of class I histone deacetylases (HDACs) increased lysine-199 acetylation on CapZβ1, which increased Kfrap of CapZ and stimulated actin dynamics. Finally, we show that PE treatment of NRVMs results in decreased binding of HDAC3 to myofibrils, suggesting a signal-dependent mechanism for the regulation of sarcomere-associated CapZβ1 acetylation. Taken together, this dual regulation through phosphorylation and acetylation of CapZβ1 provides a novel model for the regulation of myofibril growth during cardiac hypertrophy. Copyright © 2016. Published by Elsevier Inc.

  18. Structure of the N-terminal domain of the adenylyl cyclase-associated protein (CAP) from Dictyostelium discoideum.

    PubMed

    Ksiazek, Dorota; Brandstetter, Hans; Israel, Lars; Bourenkov, Gleb P; Katchalova, Galina; Janssen, Klaus-Peter; Bartunik, Hans D; Noegel, Angelika A; Schleicher, Michael; Holak, Tad A

    2003-09-01

    Cyclase-associated proteins (CAPs) are widely distributed and highly conserved proteins that regulate actin remodeling in response to cellular signals. The N termini of CAPs play a role in Ras signaling and bind adenylyl cyclase; the C termini bind to G-actin and thereby alter the dynamic rearrangements of the microfilament system. We report here the X-ray structure of the core of the N-terminal domain of the CAP from Dictyostelium discoideum, which comprises residues 51-226, determined by a combination of single isomorphous replacement with anomalous scattering (SIRAS). The overall structure of this fragment is an alpha helix bundle composed of six antiparallel helices. Results from gel filtration and crosslinking experiments for CAP(1-226), CAP(255-464), and the full-length protein, together with the CAP N-terminal domain structure and the recently determined CAP C-terminal domain structure, provide evidence that the functional structure of CAP is multimeric.

  19. Regulation of phytochrome message abundance in root caps of maize

    NASA Technical Reports Server (NTRS)

    Johnson, E. M.; Pao, L. I.; Feldman, L. J.

    1991-01-01

    In many cultivars of maize (Zea mays L.) red light affects root development via the photomorphogenetic pigment phytochrome. The site of perception for the light is the root cap. In the maize cultivar Merit, we investigated phytochrome-mediated events in the cap. We established that the message encoded by the phyA1 gene was most abundant in dark-grown tissue and was asymmetrically distributed in the root cap, with greatest expression in the cells which make up the central columella core of the cap. Phytochrome message was negatively autoregulated in a specific region within the root cap. This autoregulation was sensitive to very-low-fluence red light, and thus was characterized as a phytochrome-mediated, very-low-fluence event. The kinetics of message reaccumulation in the dark were also examined and compared to the kinetics of the light requirement for root gravitropism in this cultivar. Similarly, the degree of autoregulation present in two other maize cultivars with different light requirements for gravitropic sensitivity was investigated. It appears that the Merit cultivar expresses a condition of hypersensitivity to phytochrome-mediated light regulation in root tissues. We conclude that phytochrome regulates many activities within the cap, but the degree to which these activities share common phytochrome-mediated steps is not known.

  20. South Polar Cap

    NASA Technical Reports Server (NTRS)

    2004-01-01

    [figure removed for brevity, see original site]

    Released 8 March 2004

    The Odyssey spacecraft has completed a full Mars year of observations of the red planet. For the next several weeks the Image of the Day will look back over this first mars year. It will focus on four themes: 1) the poles - with the seasonal changes seen in the retreat and expansion of the caps; 2) craters - with a variety of morphologies relating to impact materials and later alteration, both infilling and exhumation; 3) channels - the clues to liquid surface flow; and 4) volcanic flow features. While some images have helped answer questions about the history of Mars, many have raised new questions that are still being investigated as Odyssey continues collecting data as it orbits Mars.

    This image was collected March 5, 2002 during the southern summer season. Layering in the South polar cap interior is readily visible and may indicate yearly ice/dust deposition.

    Image information: VIS instrument. Latitude -86.6, Longitude 156.8 East (203.2 West). 19 meter/pixel resolution.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the

  1. Which Core Matters More? Differences in Definitions of Quality Lead to New Debates over the Importance of Teaching Practical Skills versus Specific Knowledge

    ERIC Educational Resources Information Center

    Berrett, Dan

    2012-01-01

    Potential students hoping to gauge the quality of courses at Portland State University might be forgiven for feeling confused. On the one hand, the University Studies program, which uses interdisciplinary seminars during the first two years to develop students' core skills, has been widely praised and emulated. The Council for Higher Education…

  2. Identification of cytoplasmic capping targets reveals a role for cap homeostasis in translation and mRNA stability

    PubMed Central

    Mukherjee, Chandrama; Patil, Deepak P.; Kennedy, Brian A.; Bakthavachalu, Baskar; Bundschuh, Ralf; Schoenberg, Daniel R.

    2012-01-01

    Summary The notion that decapping leads irreversibly to mRNA decay changed with the identification of capped transcripts missing portions of their 5′ ends and a cytoplasmic complex that can restore the cap on uncapped mRNAs. The current study used accumulation of uncapped transcripts in cells inhibited for cytoplasmic capping to identify the targets of this pathway. Inhibition of cytoplasmic capping resulted in the destabilization of some transcripts and the redistribution of others from polysomes to non-translating mRNPs, where they accumulate in an uncapped state. Only a portion of the mRNA transcriptome is affected by cytoplasmic capping, and its targets encode proteins involved in nucleotide binding, RNA and protein localization and the mitotic cell cycle. The 3′-UTRs of recapping targets are enriched for AU-rich elements and microRNA binding sites, both of which function in cap-dependent mRNA silencing. These findings identify a cyclical process of decapping and recapping we term cap homeostasis. PMID:22921400

  3. A "Cap" on Medicaid: How Block Grants, Per Capita Caps, and Capped Allotments Might Fundamentally Change the Safety Net.

    PubMed

    Mager-Mardeusz, Haleigh; Lenz, Cosima; Kominski, Gerald F

    2017-04-01

    Changing the Medicaid program is a top priority for the Republican party. Common themes from GOP proposals include converting Medicaid from a jointly financed entitlement benefit to a form of capped federal financing. While proponents of this reform argue that it would provide greater flexibility and a more predictable budget for state governments, serious consequences would likely result for Medicaid enrollees and state governments. Under all three scenarios promoted by Republicans--block grants, capped allotments, and per capita caps—most states would face increased costs. For all three scenarios, the capped nature of the funding guarantees that the real value of funds would decrease in future years relative to what would be expected from growth under the current program. Although the federal government would undoubtedly realize savings from all three scenarios, the impact might lead states to reduce benefits and services, create waiting lists, impose cost-sharing on a traditionally low-income enrollee population, or impose other obstacles to coverage. Nationally, as many as 20.5 million Americans stand to lose coverage under the proposed Medicaid changes. In California, up to 6 million people could lose coverage if changes to the Medicaid program were coupled with the repeal of coverage for the expansion population.

  4. Refilin holds the cap.

    PubMed

    Gay, Olivia; Nakamura, Fumihiko; Baudier, Jacques

    2011-11-01

    The Refilins (RefilinA and RefilinB) are a novel family of short-lived actin regulatory proteins that are expressed during changes in cellular phenotype such as epithelial to mesenchymal transition (EMT). The Refilins promote to the formation of actin- and myosin-rich perinuclear bundles that are characteristic of cellular phenotypic switches. In epithelial cells, RefilinB is up-regulated in response to TGF-β stimulation and function in organization of apical perinuclear actin fibers during early stage of the EMT process1. In fibroblasts, RefilinB stabilizes perinuclear parallel actin bundles which resemble actin cap 2. Refilins bind and modulate the function of Filamin A (FLNA). Upon binding to Refilins, FLNA is capable of assembling actin filaments into parallel bundles, possibly by undergoing conformational changes at the C-terminal. Perinuclear actin structures determine nuclear shape, cell morphology, cell adhesion and possibly cell proliferation and gene regulation. Identifying the role of Refilins in organizing perinuclear actin networks provides additional insight in the process of intracellular mechanotransduction that regulate changes in cellular phenotype such as those observed during EMT.

  5. Refilin holds the cap

    PubMed Central

    Gay, Olivia; Nakamura, Fumihiko

    2011-01-01

    The Refilins (RefilinA and RefilinB) are a novel family of short-lived actin regulatory proteins that are expressed during changes in cellular phenotype such as epithelial to mesenchymal transition (EMT). The Refilins promote to the formation of actin- and myosin-rich perinuclear bundles that are characteristic of cellular phenotypic switches. In epithelial cells, RefilinB is up-regulated in response to TGF-β stimulation and function in organization of apical perinuclear actin fibers during early stage of the EMT process1. In fibroblasts, RefilinB stabilizes perinuclear parallel actin bundles which resemble actin cap 2. Refilins bind and modulate the function of Filamin A (FLNA). Upon binding to Refilins, FLNA is capable of assembling actin filaments into parallel bundles, possibly by undergoing conformational changes at the C-terminal. Perinuclear actin structures determine nuclear shape, cell morphology, cell adhesion and possibly cell proliferation and gene regulation. Identifying the role of Refilins in organizing perinuclear actin networks provides additional insight in the process of intracellular mechanotransduction that regulate changes in cellular phenotype such as those observed during EMT. PMID:22446558

  6. Numerical modeling of experimental human fibrous cap delamination.

    PubMed

    Leng, Xiaochang; Davis, Lindsey A; Deng, Xiaomin; Sutton, Michael A; Lessner, Susan M

    2016-06-01

    Fibrous cap delamination is a critical process during the rupture of atherosclerotic plaque, which often leads to severe life-threatening clinical consequences such as myocardial infarction or stroke. In this study a finite element modeling and simulation approach is presented that enables the study of fibrous cap delamination experiments for the purpose of understanding the fibrous cap delamination process. A cohesive zone model (CZM) approach is applied to simulate delamination of the fibrous cap from the underlying plaque tissue. A viscoelastic anisotropic (VA) model for the bulk arterial material behavior is extended from existing studies so that the hysteresis phenomenon observed in the fibrous cap delamination experiments can be captured. A finite element model is developed for the fibrous cap delamination experiments, in which arterial layers (including the fibrous cap and the underlying plaque tissue) are represented by solid elements based on the VA model and the fibrous cap-underlying plaque tissue interface is characterized by interfacial CZM elements. In the CZM, the delamination process is governed by an exponential traction-separation law which utilizes critical energy release rates obtained directly from the fibrous cap delamination experiments. A set of VA model parameter values and CZM parameter values is determined based on values suggested in the literature and through matching simulation predictions of the load vs. load-point displacement curve with one set of experimental measurements. Using this set of parameter values, simulation predictions for other sets of experimental measurements are obtained and good agreement between simulation predictions and experimental measurements is observed. Results of this study demonstrate the applicability of the viscoelastic anisotropic model and the CZM approach for the simulation of diseased arterial tissue failure processes. Copyright © 2016 Elsevier Ltd. All rights reserved.

  7. CAPS1 Negatively Regulates Hepatocellular Carcinoma Development through Alteration of Exocytosis-Associated Tumor Microenvironment

    PubMed Central

    Xue, Ruyi; Tang, Wenqing; Dong, Pingping; Weng, Shuqiang; Ma, Lijie; Chen, She; Liu, Taotao; Shen, Xizhong; Huang, Xiaowu; Zhang, Si; Dong, Ling

    2016-01-01

    The calcium-dependent activator protein for secretion 1 (CAPS1) regulates exocytosis of dense-core vesicles (DCVs) in neurons and neuroendocrine cells. The role of CAPS1 in cancer biology remains unknown. The purpose of this study was to investigate the role of CAPS1 in hepatocellular carcinoma (HCC). We determined the levels of CAPS1 in eight hepatoma cell lines and 141 HCC specimens. We evaluated the prognostic value of CAPS1 expression and its association with clinical parameters. We investigated the biological consequences of CAPS1 overexpression in two hepatoma cell lines in vitro and in vivo. The results showed that loss of CAPS1 expression in HCC tissues was markedly correlated with aggressive tumor phenotypes, such as high-grade tumor node metastasis (TNM) stage (p = 0.003) and absence of tumor encapsulation (p = 0.016), and was associated with poor overall survival (p = 0.008) and high recurrence (p = 0.015). CAPS1 overexpression inhibited cell proliferation and migration by changing the exocytosis-associated tumor microenvironment in hepatoma cells in vitro. The in vivo study showed that CAPS1 overexpression inhibited xenograft tumor growth. Together, these results identified a previously unrecognized tumor suppressor role for CAPS1 in HCC development. PMID:27689999

  8. Crustal thickening leading to exhumation of the Himalayan Metamorphic core of central Nepal: Insight from U-Pb Geochronology and 40Ar/39Ar Thermochronology

    NASA Astrophysics Data System (ADS)

    Godin, Laurent; Parrish, Randall R.; Brown, Richard L.; Hodges, Kip V.

    2001-10-01

    New and published U-Pb geochronology and 40Ar/39Ar thermochronology from footwall and hanging wall rocks of a segment of the South Tibetan detachment system exposed in the Annapurna area of central Nepal Himalaya bring additional constraints on the timing of metamorphism, crustal thickening, and normal faulting resulting in exhumation of the Himalayan metamorphic core. Early Oligocene crustal thickening led to Eohimalayan kyanite-grade metamorphism between 35 Ma and 32 Ma. The resulting thermal event affected the Early Ordovician augen gneiss (Formation III) and produced kyanite-bearing leucosomes in the upper part of the metamorphic core. This event is linked with underthrusting of the Greater Himalayan metamorphic sequence below the Tethyan sedimentary sequence and the growth of an Oligocene fan structure that has thickened the Tethyan sedimentary sequence to 25 km, thus provoking kyanite-grade melting at deeper structural levels. Early Paleozoic monazite and zircon populations indicate that part of the metamorphism affecting the Himalayan metamorphic core could be pre-Cenozoic. Regional correlations indicate that the Annapurna detachment was active during early Miocene time. A weakly deformed leucogranitic dike intruding into the immediate hanging wall yielded reversely discordant monazite ages between 23 and 22.5 Ma, which suggest that the ductile strain in the Annapurna detachment zone terminated at ca. 22 Ma. On the basis of a 40Ar/39Ar muscovite age, renewed southwest verging deformation (D4) is interpreted to occur at ca. 18 Ma. Rapid exhumation resulting from extensional faulting cooled the entire metamorphic core through the muscovite Ar closure temperature (330°-430°C) between 15 and 13 Ma. Muscovites from the immediate hanging wall of the Annapurna detachment yielded slightly younger ages, between 13 and 11 Ma, testifying to late hydrothermal activity in the Annapurna detachment zone that could be linked with the initiation of brittle faulting

  9. Biophysical approach to studies of cap-eIF4E interaction by synthetic cap analogs.

    PubMed

    Niedzwiecka, Anna; Stepinski, Janusz; Antosiewicz, Jan M; Darzynkiewicz, Edward; Stolarski, Ryszard

    2007-01-01

    Specific recognition of mRNA 5' cap by eukaryotic initiation factor eIF4E is a rate-limiting step in the translation initiation. Structural determination of the eIF4E-cap complexes, as well as complexes of eIF4E with other proteins regulating its activity, requires complementary experiments that allow for energetic and dynamic aspects of formation and stability of the complexes. Such a combined approach provides information on the binding mechanisms and, hence, may lead to mechanistic models of eIF4E functioning and regulation on the molecular level. This chapter summarizes in detail the method of experiments used to probe the cap-binding center of eIF4E, steady state and stopped-flow fluorescence, and microcalorimetry. The studies were performed with a wide class of synthetic, structurally modified cap analogs that resembles in some respect an application of site directed mutagenesis of the protein. The chapter presents a general recipe as to how to investigate protein-ligand interactions if the protein has no enzymatic activity and both the protein and the ligand absorb and emit UV/VIS radiation in the same spectral ranges.

  10. Ferroelectric capped magnetization in multiferroic PZT/LSMO tunnel junctions

    SciTech Connect

    Kumar, Ashok Shukla, A. K.; Barrionuevo, D.; Ortega, N.; Katiyar, Ram S.; Shannigrahi, Santiranjan; Scott, J. F.

    2015-03-30

    Self-poled ultra-thin ferroelectric PbZr{sub 0.52}Ti{sub 0.48}O{sub 3} (PZT) (5 and 7 nm) films have been grown by pulsed laser deposition technique on ferromagnetic La{sub 0.67}Sr{sub 0.33}MnO{sub 3} (LSMO) (30 nm) to check the effect of polar capping on magnetization for ferroelectric tunnel junction devices. PZT/LSMO heterostructures with thick polar PZT (7 nm) capping show nearly 100% enhancement in magnetization compared with thin polar PZT (5 nm) films, probably due to excess hole transfer from the ferroelectric to the ferromagnetic layers. Core-level x-ray photoelectron spectroscopy studies revealed the presence of larger Mn 3s exchange splitting and higher Mn{sup 3+}/Mn{sup 4+} ion ratio in the LSMO with 7 nm polar capping.

  11. Cradle Cap: Symptoms and Causes

    MedlinePlus

    ... scalp Oily or dry skin covered with flaky white or yellow scales Skin flakes Possibly mild redness Similar scales may also be present on the ears, eyelids, nose and groin. Cradle cap is common in newborns. ...

  12. Stuck fuel rod capping sleeve

    DOEpatents

    Gorscak, Donald A.; Maringo, John J.; Nilsen, Roy J.

    1988-01-01

    A stuck fuel rod capping sleeve to be used during derodding of spent fuel assemblies if a fuel rod becomes stuck in a partially withdrawn position and, thus, has to be severed. The capping sleeve has an inner sleeve made of a lower work hardening highly ductile material (e.g., Inconel 600) and an outer sleeve made of a moderately ductile material (e.g., 304 stainless steel). The inner sleeve may be made of an epoxy filler. The capping sleeve is placed on a fuel rod which is then severed by using a bolt cutter device. Upon cutting, the capping sleeve deforms in such a manner as to prevent the gross release of radioactive fuel material

  13. Northern Ice Cap of Mars

    NASA Image and Video Library

    2010-05-26

    This image, combining data from two instruments aboard NASA Mars Global Surveyor, depicts an orbital view of the north polar region of Mars. To the right of center, a large canyon, Chasma Boreale, almost bisects the white ice cap.

  14. Cocaine Self-Administration and Extinction Leads to Reduced Glial Fibrillary Acidic Protein Expression and Morphometric Features of Astrocytes in the Nucleus Accumbens Core.

    PubMed

    Scofield, Michael D; Li, Hao; Siemsen, Benjamin M; Healey, Kati L; Tran, Phuong K; Woronoff, Nicholas; Boger, Heather A; Kalivas, Peter W; Reissner, Kathryn J

    2016-08-01

    As a more detailed picture of nervous system function emerges, diversity of astrocyte function becomes more widely appreciated. While it has been shown that cocaine experience impairs astroglial glutamate uptake and release in the nucleus accumbens (NAc), few studies have explored effects of self-administration on the structure and physiology of astrocytes. We investigated the effects of extinction from daily cocaine self-administration on astrocyte characteristics including glial fibrillary acidic protein (GFAP) expression, surface area, volume, and colocalization with a synaptic marker. Cocaine or saline self-administration and extinction were paired with GFAP Westerns, immunohistochemistry, and fluorescent imaging of NAc core astrocytes (30 saline-administering and 36 cocaine-administering male Sprague Dawley rats were employed). Imaging was performed using a membrane-tagged lymphocyte protein tyrosine kinase-green fluorescent protein (Lck-GFP) driven by the GFAP promoter, coupled with synapsin I immunohistochemistry. GFAP expression was significantly reduced in the NAc core following cocaine self-administration and extinction. Similarly, we observed an overall smaller surface area and volume of astrocytes, as well as reduced colocalization with synapsin I, in cocaine-administering animals. Cocaine-mediated reductions in synaptic contact were reversed by the β-lactam antibiotic ceftriaxone. Multiple lines of investigation indicate that NAc core astrocytes exist in a hyporeactive state following cocaine self-administration and extinction. Decreased association with synaptic elements may be particularly meaningful, as cessation of chronic cocaine use is associated with changes in synaptic strength and resistance to the induction of synaptic plasticity. We hypothesize that the reduced synaptic colocalization of astrocytes represents an important maladaptive cellular response to cocaine and the mechanisms underlying relapse vulnerability. Copyright © 2016 Society

  15. Comparison of human CAP and CAP2, homologs of the yeast adenylyl cyclase-associated proteins.

    PubMed

    Yu, G; Swiston, J; Young, D

    1994-06-01

    We previously reported the identification of human CAP, a protein that is related to the Saccharomyces cerevisiae and Schizosaccharomyces pombe adenylyl cyclase-associated CAP proteins. The two yeast CAP proteins have similar functions: the N-terminal domains are required for the normal function of adenylyl cyclase, while loss of the C-terminal domains result in morphological and nutritional defects that are unrelated to the cAMP pathways. We have amplified and cloned cDNAs from a human glioblastoma library that encode a second CAP-related protein, CAP2. The human CAP and CAP2 proteins are 64% identical. Expression of either human CAP or CAP2 in S. cerevisiae cap- strains suppresses phenotypes associated with deletion of the C-terminal domain of CAP, but does not restore hyper-activation of adenylyl cyclase by RAS2val19. Similarly, expression of either human CAP or CAP2 in S. pombe cap- strains suppresses the morphological and temperature-sensitive phenotypes associated with deletion of the C-terminal domain of CAP in this yeast. In addition, expression of human CAP, but not CAP2, suppresses the propensity to sporulate due to deletion of the N-terminal domain of CAP in S. pombe. This latter observation suggests that human CAP restores normal adenylyl cyclase activity in S. pombe cap- cells. Thus, functional properties of both N-terminal and C-terminal domains are conserved between the human and S. pombe CAP proteins.

  16. Late-glacial and Holocene history of changes in Quelccaya Ice Cap, Peru

    NASA Astrophysics Data System (ADS)

    Kelly, M. A.; Lowell, T. V.; Schaefer, J. M.; Finkel, R. C.

    2008-12-01

    Quelccaya Ice Cap in the southeastern Peruvian Andes (~13-14° S latitude) is an icon for climate change. Its rapidly receding outlet, Qori Kalis Glacier, has been monitored since the 1970's. Cores from Quelccaya Ice Cap provide high-resolution information about temperature and precipitation during the past 1,500 years. We extend the understanding of past changes in Quelccaya Ice Cap based on mapping and dating of glacial moraines and associated deposits. Our results include fifty 10Be ages of moraines and bedrock as well as twenty-nine 14C ages of organic material associated with moraines. These results form the basis of a chronology of changes in Quelccaya Ice Cap from ~16,000 yr BP to late Holocene time. Results from 10Be and 14C dating indicate that Quelccaya Ice Cap experienced a significant advance at 12,700-11,400 yr BP. Subsequent to this advance, the ice margin deposited at least three recessional moraine sets. Quelccaya Ice Cap receded to near its present-day margin by ~10,000 yr BP. Neoglacial advances began by ~3,000 yr BP and culminated with a maximum advance during the Little Ice Age. This chronology fits well with prior work which indicates a restricted Quelccaya Ice Cap during middle Holocene time. Moreover, the overlap between moraine and ice core data for the last 1,500 years provides a unique opportunity to assess the influences of temperature and precipitation on past ice cap extents.

  17. 47 CFR 54.623 - Cap.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 3 2010-10-01 2010-10-01 false Cap. 54.623 Section 54.623 Telecommunication... Universal Service Support for Health Care Providers § 54.623 Cap. (a) Amount of the annual cap. The annual cap on federal universal service support for health care providers shall be $400 million per funding...

  18. Polar Cap Colors

    NASA Technical Reports Server (NTRS)

    2004-01-01

    [figure removed for brevity, see original site]

    Released 12 May 2004 This daytime visible color image was collected on June 6, 2003 during the Southern Spring season near the South Polar Cap Edge.

    The THEMIS VIS camera is capable of capturing color images of the martian surface using its five different color filters. In this mode of operation, the spatial resolution and coverage of the image must be reduced to accommodate the additional data volume produced from the use of multiple filters. To make a color image, three of the five filter images (each in grayscale) are selected. Each is contrast enhanced and then converted to a red, green, or blue intensity image. These three images are then combined to produce a full color, single image. Because the THEMIS color filters don't span the full range of colors seen by the human eye, a color THEMIS image does not represent true color. Also, because each single-filter image is contrast enhanced before inclusion in the three-color image, the apparent color variation of the scene is exaggerated. Nevertheless, the color variation that does appear is representative of some change in color, however subtle, in the actual scene. Note that the long edges of THEMIS color images typically contain color artifacts that do not represent surface variation.

    Image information: VIS instrument. Latitude -77.8, Longitude 195 East (165 West). 38 meter/pixel resolution.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA

  19. Hypermethylated-capped selenoprotein mRNAs in mammals

    PubMed Central

    Wurth, Laurence; Gribling-Burrer, Anne-Sophie; Verheggen, Céline; Leichter, Michael; Takeuchi, Akiko; Baudrey, Stéphanie; Martin, Franck; Krol, Alain; Bertrand, Edouard; Allmang, Christine

    2014-01-01

    Mammalian mRNAs are generated by complex and coordinated biogenesis pathways and acquire 5′-end m7G caps that play fundamental roles in processing and translation. Here we show that several selenoprotein mRNAs are not recognized efficiently by translation initiation factor eIF4E because they bear a hypermethylated cap. This cap modification is acquired via a 5′-end maturation pathway similar to that of the small nucle(ol)ar RNAs (sn- and snoRNAs). Our findings also establish that the trimethylguanosine synthase 1 (Tgs1) interacts with selenoprotein mRNAs for cap hypermethylation and that assembly chaperones and core proteins devoted to sn- and snoRNP maturation contribute to recruiting Tgs1 to selenoprotein mRNPs. We further demonstrate that the hypermethylated-capped selenoprotein mRNAs localize to the cytoplasm, are associated with polysomes and thus translated. Moreover, we found that the activity of Tgs1, but not of eIF4E, is required for the synthesis of the GPx1 selenoprotein in vivo. PMID:25013170

  20. Enhanced thermal stability of phosphate capped magnetite nanoparticles

    SciTech Connect

    Muthukumaran, T.; Philip, John

    2014-06-14

    We have studied the effect of phosphate capping on the high temperature thermal stability and magnetic properties of magnetite (Fe{sub 3}O{sub 4}) nanoparticles synthesized through a single-step co-precipitation method. The prepared magnetic nanoparticles are characterized using various techniques. When annealed in air, the phosphate capped nanoparticle undergoes a magnetic to non-magnetic phase transition at a temperature of 689 °C as compared to 580 °C in the uncoated nanoparticle of similar size. The observed high temperature phase stability of phosphate capped nanoparticle is attributed to the formation of a phosphocarbonaceous shell over the nanoparticles, which acts as a covalently attached protective layer and improves the thermal stability of the core material by increasing the activation energy. The phosphocarbonaceous shell prevents the intrusion of heat, oxygen, volatiles, and mass into the magnetic core. At higher temperatures, the coalescence of nanoparticles occurs along with the restructuring of the phosphocarbonaceous shell into a vitreous semisolid layer on the nanoparticles, which is confirmed from the small angle X-ray scattering, Fourier transform infra red spectroscopy, and transmission electron microscopy measurements. The probable mechanism for the enhancement of thermal stability of phosphocarbonaceous capped nanoparticles is discussed.

  1. Immunization with Recombinant Adenoviral Vectors Expressing HCV Core or F Proteins Leads to T Cells with Reduced Effector Molecules Granzyme B and IFN-γ: A Potential New Strategy for Immune Evasion in HCV Infection.

    PubMed

    Samrat, Subodh Kumar; Vedi, Satish; Singh, Shakti; Li, Wen; Kumar, Rakesh; Agrawal, Babita

    2015-01-01

    Multispecific, broad, and potent T cell responses have been correlated with viral clearance in hepatitis C virus (HCV) infection. However, the majority of infected patients develop chronic infection, suggesting that natural infection mostly leads to development of inefficient T cell immunity. Multiple mechanisms of immune modulation and evasion have been shown in HCV infection through various investigations. This study examined the generation and modulation of T cell responses against core and frameshift (F) proteins of HCV. A single immunization of mice with replication incompetent recombinant adenovirus vectors encoding for F or core antigens induces poor T cell responses and leads to generation of CD4+ and CD8+ T cells with low granzyme B (GrB) expression. These T cells have impaired GrB enzyme activity and are unable to kill peptide loaded target cells. The low intracellular expression of GrB is not due to degranulation of cytotoxic granules containing cytotoxic T cells. Addition of exogenous IL-2 in in vitro cultures leads to partial recovery of GrB production, whereas immunization with the Toll-like receptor (TLR) agonist poly I:C leads to complete restoration of GrB expression in both CD4+ and CD8+ T cells. Thus, a possible new strategy of T cell modulation is recognized wherein effector T cells are caused to be dysfunctional by HCV-derived antigens F or core, and strategies are also delineated to overcome this dysfunction. These studies are important in the investigation of prophylactic vaccine and immunotherapy strategies for HCV infection.

  2. The Drangajökull ice cap, northwest Iceland, persisted into the early-mid Holocene

    NASA Astrophysics Data System (ADS)

    Schomacker, Anders; Brynjólfsson, Skafti; Andreassen, Julie M.; Gudmundsdóttir, Esther Ruth; Olsen, Jesper; Odgaard, Bent V.; Håkansson, Lena; Ingólfsson, Ólafur; Larsen, Nicolaj K.

    2016-09-01

    Most glaciers and ice caps in Iceland experienced rapid deglaciation in the early Holocene, reaching a minimum extent during the Holocene Thermal Maximum. Here we present evidence of the Holocene glacial history from lake sediment cores retrieved from seven threshold lakes around the Drangajökull ice cap in the Vestfirðir peninsula, NW Iceland. The sediment cores show on/off signals of glacial meltwater activity, as minerogenic material deposited from glacial meltwater alternates with organic-rich material (gyttja) deposited without glacial meltwater. We base the chronology of the sediment cores on 14C ages and geochemical identification of key tephra layers with known ages. A 25-cm thick layer of the Saksunarvatn tephra in Lake Skorarvatn indicates that the northern part of the ice cap had reached a similar size as today or was smaller already by 10.2 cal kyr BP. However, 14C ages of lake sediment cores from the highlands southeast of Drangajökull suggest that this part of the ice cap was larger than today until 7.8-7.2 cal kyr BP. Even today, the Drangajökull ice cap has a different behavior than the main ice caps in Iceland, characterized by a very low glaciation limit. Because palaeoclimatic proxies show an early-mid Holocene temperature optimum in this part of Iceland, we suggest that the persistence of Drangajökull into the early Holocene and, possibly, also the entire Holocene was due to high winter precipitation.

  3. Creation of polar cap patches

    NASA Astrophysics Data System (ADS)

    Hosokawa, K.; Taguchi, S.; Ogawa, Y.

    2014-12-01

    Polar cap patches, which are islands of enhanced plasma density drifting anti-sunward, are one of the outstanding phenomena in the polar cap F region ionosphere. In the last decade, data from all-sky airglow imagers have been extensively used for better understanding the propagation of patches in the central polar cap region. But still, it has been rather difficult to capture the birth of patches in their generation region near the dayside cusp, because, in most places, the dayside part of the polar cap ionosphere is sunlit even in winter. In Longyearbyen (78.1N, 15.5E), Norway, however, optical observations are possible near the dayside cusp region in a limited period around the winter solstice. This enables us to directly image how polar cap patches are born in the cusp. In this paper, we present a few intervals of daytime optical observations, during which polar cap patches were generated within the field-of-view of an all-sky imager in Longyearbyen. During all the intervals studied here, we identified several signatures of poleward moving auroral forms (PMAF) in the equatorward half of the field-of-view, which are known as ionospheric manifestations of dayside reconnection. Interestingly, patches were directly produced from such poleward moving auroral signatures and propagated poleward along the anti-sunward convection near the cusp. In the literature, Lorentzen et al. (2012) first reported such a direct production of patches from PMAFs. During the current observations, however, we succeeded in tracking the propagation of patches until they reached the poleward edge of the field-of-view of the imager. This confirms that the faint airglow structures produced from PMAFs were actually transported for a long distance towards the central polar cap area; thus, polar cap patches were produced. From this set of observations, we suggest that polar cap patches during moderately disturbed conditions (i.e, non-storm time conditions) can be directly produced by the

  4. A new approach for quantifying cumulative, anthropogenic, atmospheric lead deposition using peat cores from bogs: Pb in eight Swiss peat bog profiles.

    PubMed

    Shotyk, W; Blaser, P; Grünig, A; Cheburkin, A K

    2000-04-17

    Peat cores taken from eight Swiss peatlands were used to calculate inventories of anthropogenic Pb using either Sc or Zr to quantify Pb derived from rock weathering. The shapes of the Pb/Sc and Pb/Zr profiles suggest that Pb was supplied exclusively by atmospheric deposition at all sites. At one of the sites (Etang de la Gruère), anthropogenic Pb was calculated using both Sc and Zr as the conservative reference element. Lithogenic Pb determined using Sc was twice that obtained using Zr, possibly because Zr resides only in zircons which are dense compared to pyroxene and amphibole which are the main Sc-bearing phases in the earth's crust. However, the inventory of 'natural' Pb (supplied almost entirely by soil dust) is dwarfed by the anthropogenic inventory such that anthropogenic Pb calculated using Sc and Zr agree to within 5%. The total amount of anthropogenic Pb accumulated in the bogs was calculated by simply adding the mass of anthropogenic Pb for each peat slice over the length of each core. Cumulative, anthropogenic Pb calculated in this way ranged from 1.0 to 9.7 g/m2 and showed pronounced regional differences: the site south of the Alps (Gola di Lago in Canton Ticino) with direct exposure to the heavily industrialized region of northern Italy received nearly 10 times more anthropogenic Pb as the sites in more remote alpine regions (Schöpfenwaldmoor in Canton Berne, and Mauntschas in Canton Grisons). The approach used here to calculate cumulative, anthropogenic, atmospheric Pb (CAAPb) is simple and robust, independent of the chronology of Pb deposition, and makes no assumptions about the immobility of Pb within the peat profile. Given the worldwide distribution of peat bogs, it should be possible to undertake continental and global inventories of atmospheric metal deposition, for both the natural and anthropogenic components of most trace metals of environmental interest.

  5. Mathematical modeling of cold cap

    SciTech Connect

    Pokorny, Richard; Hrma, Pavel R.

    2012-10-13

    The ultimate goal of studies of cold cap behavior in glass melters is to increase the rate of glass processing in an energy-efficient manner. Regrettably, mathematical models, which are ideal tools for assessing the responses of melters to process parameters, have not paid adequate attention to the cold cap. In this study, we consider a cold cap resting on a pool of molten glass from which it receives a steady heat flux while temperature, velocity, and extent of conversion are functions of the position along the vertical coordinate. A one-dimensional (1D) mathematical model simulates this process by solving the differential equations for mass and energy balances with appropriate boundary conditions and constitutive relationships for material properties. The sensitivity analyses on the effects of incoming heat fluxes to the cold cap through its lower and upper boundaries show that the cold cap thickness increases as the heat flux from above increases, and decreases as the total heat flux increases. We also discuss the effects of foam, originating from batch reactions and from redox reactions in molten glass and argue that models must represent the foam layer to achieve a reliable prediction of the melting rate as a function of feed properties and melter conditions.

  6. South Polar Residual Ice Cap

    NASA Technical Reports Server (NTRS)

    1990-01-01

    This mosaic is composed of 18 Viking Orbiter images (6 each in red, green, and violet filters), acquired on September 28, 1977, during revolution 407 of Viking Orbiter 2. The south pole is located just off the lower left edge of the polar cap, and the 0 degree longitude meridian extends toward the top of the mosaic. The large crater near the right edge (named 'South') is about 100 km in diameter. These images were acquired during southern summer on Mars (Ls = 341 degrees); the sub-solar declination was 8 degrees S., and the south polar cap was nearing its final stage of retreat just prior to vernal equinox. The south residual cap is approximately 400 km across, and the exposed surface is thought to consist dominantly of carbon-dioxide frost. This is in contrast to the water-ice surface of the north polar residual cap. It is likely that water ice is present in layers that underlie the south polar cap and that comprise the surrounding layered terrains. Near the top of this image, irregular pits with sharp-rimmed cliffs appear 'etched', presumably by wind. A series of rugged mountains (extending toward the upper right corner of the image) are of unknown origin.

  7. South Polar Residual Ice Cap

    NASA Technical Reports Server (NTRS)

    1990-01-01

    This mosaic is composed of 18 Viking Orbiter images (6 each in red, green, and violet filters), acquired on September 28, 1977, during revolution 407 of Viking Orbiter 2. The south pole is located just off the lower left edge of the polar cap, and the 0 degree longitude meridian extends toward the top of the mosaic. The large crater near the right edge (named 'South') is about 100 km in diameter. These images were acquired during southern summer on Mars (Ls = 341 degrees); the sub-solar declination was 8 degrees S., and the south polar cap was nearing its final stage of retreat just prior to vernal equinox. The south residual cap is approximately 400 km across, and the exposed surface is thought to consist dominantly of carbon-dioxide frost. This is in contrast to the water-ice surface of the north polar residual cap. It is likely that water ice is present in layers that underlie the south polar cap and that comprise the surrounding layered terrains. Near the top of this image, irregular pits with sharp-rimmed cliffs appear 'etched', presumably by wind. A series of rugged mountains (extending toward the upper right corner of the image) are of unknown origin.

  8. Diverse role of three tyrosines in binding of the RNA 5' cap to the human nuclear cap binding complex.

    PubMed

    Worch, Remigiusz; Jankowska-Anyszka, Marzena; Niedzwiecka, Anna; Stepinski, Janusz; Mazza, Catherine; Darzynkiewicz, Edward; Cusack, Stephen; Stolarski, Ryszard

    2009-01-16

    The heterodimeric nuclear cap-binding complex (CBC) specifically recognizes the monomethylguanosine 5' cap structure of the eukaryotic RNA polymerase II transcripts such as mRNA and U snRNA. The binding is essential for nuclear maturation of mRNA, for nuclear export of U snRNA in metazoans, and for nonsense-mediated decay of mRNA and the pioneer round of translation. We analysed the recognition of the cap by native human CBC and mutants in which each tyrosine that stacks with the 7-methylguanosine moiety was replaced by phenylalanine or alanine and both tyrosines were replaced by phenylalanines. The equilibrium association constants (K(as)) for two selected cap analogues, P(1)-7-methylguanosine-5' P(3)-guanosine-5' triphosphate and 7-methylguanosine triphosphate, were determined by two independent methods, fluorescence titration and surface plasmon resonance. We could distinguish two tyrosines, Y43 and Y20, in stabilization of the cap inside the CBC-binding pocket. In particular, lack of Y20 in CBC leads to a greater affinity of the mono- than the dinucleotide cap analogue, in contrast to the wild-type protein. A crucial role of cation-pi stacking in the mechanism of the specific cap recognition by CBC was postulated from the comparison of the experimentally derived Gibbs free binding energy (DeltaG degrees) with the stacking energy (DeltaE) of the 7-methylguanosine/Y binary and ternary complexes calculated by the Møller-Plesset second-order perturbation method. The resulting kinetic model of the association between the capped RNA and CBC, based on the experimental data and quantum calculations, is discussed with respect to the "CBC-to-eukaryotic initiation factor 4E handoff" of mRNA.

  9. Polar Cap Formation on Ganymede

    NASA Technical Reports Server (NTRS)

    Pilcher, C. B.; Shaya, E. J.

    1985-01-01

    Since thermal migration is not an effective mechanism for water transport in the polar regions at the Galilean satellites, some other process must be responsible for the formation of Ganymede's polar caps. It is proposed that Ganymede's polar caps are the optical manifestation of a process that began with the distribution of an ice sheet over the surface of Ganymede. The combined processes of impact gardening and thermal migration led, in regions at latitudes less than 40 to 45 deg., to the burial of some fraction of this ice, the migration of some to the polar caps margins, and a depletion of free ice in the optical surface. At higher latitudes, no process was effective in removing ice from the optical surface, so the remanants of the sheet are visible today.

  10. Polar cap formation on Ganymede

    NASA Technical Reports Server (NTRS)

    Shaya, E. J.; Pilcher, C. B.

    1984-01-01

    It is argued that Ganymede's polar caps are the remnants of a more extensive covering of water ice that formed during a period in which the satellite was geologically active. It is inferred that the initial thickness of this covering was a significant fraction of the gardening depth since the covering formed. This suggests an initial thickness of at least a few meters over heavily cratered regions such as the south polar grooved terrain. The absence of similar polar caps on Callisto apparently reflects the absence of comparable geologic activity in the history of this satellite.

  11. Patchy particles using colloidal caps

    NASA Astrophysics Data System (ADS)

    Middleton, Christine; Pine, David

    2015-03-01

    We present a method for making patchy particles functionalized with single stranded sticky end DNA only on their patches. This is done by adding ``spherical cap'' particles as patches to spherical colloids using the depletion interaction. The caps are then functionalized with single stranded DNA using copper-free click chemistry. Due to being attached only by depletion, the patches diffuse on the surface of the particle. The patchy particles can then interact with each other in a specific, directional way through the mobile, DNA functionalized patches.

  12. Gold nanoparticles with different capping systems: an electronic and structural XAS analysis.

    PubMed

    López-Cartes, C; Rojas, T C; Litrán, R; Martínez-Martínez, D; de la Fuente, J M; Penadés, S; Fernández, A

    2005-05-12

    Gold nanoparticles (NPs) have been prepared with three different capping systems: a tetralkylammonium salt, an alkanethiol, and a thiol-derivatized neoglycoconjugate. Also gold NPs supported on a porous TiO(2) substrate have been investigated. X-ray absorption spectroscopy (XAS) has been used to determine the electronic behavior of the different capped/supported systems regarding the electron/hole density of d states. Surface and size effects, as well as the role of the microstructure, have been also studied through an exhaustive analysis of the EXAFS (extended X-ray absorption fine structure) data. Very small gold NPs functionalized with thiol-derivatized molecules show an increase in d-hole density at the gold site due to Au-S charge transfer. This effect is overcoming size effects (which lead to a slightly increase of the d-electron density) for high S:Au atomic ratios and core-shell microstructures where an atomically abrupt Au-S interface likely does not exist. It has been also shown that thiol functionalization of very small gold NPs is introducing a strong distortion as compared to fcc order. To the contrary, electron transfer from reduced support oxides to gold NPs can produce a higher increase in d-electron density at the gold site, as compared to naked gold clusters.

  13. Climate-related changes in lead isotopes over the past 800,000 years in the EPICA Dome C Antarctic ice core

    NASA Astrophysics Data System (ADS)

    Han, C.; Hur, S.; Burn, L. J.; Gabrielli, P.; Vallelonga, P. T.; Barbante, C.; Boutron, C. F.; Hong, S.

    2013-12-01

    A record of Pb isotopic compositions from 3,260 m deep Antarctic ice, recovered at Dome C on the East Antarctic plateau, and covering the past 800 kyr, is presented. Pb isotopic compositions have been determined using thermal ionization mass spectrometry (TRITON, Thermo Scientific). All sample handling and analytical operations were performed inside a Class 1 - Class 10 clean room provided with High Efficiency Particulate Air (HEPA) multi-staged filtration (Curtin University) and under a class 10 laminar airflow bench or booth in class 1000 clean laboratories (KOPRI). Lower 206Pb/207Pb ratios are found during glacial periods when Pb concentrations are high, while higher values are found during warm periods when Pb concentrations are low. The characteristics of Pb isotopes vary with climatic conditions, which is likely associated with the relative strength of dust and volcanic contributions to Pb deposition in central East Antarctica. Using Pb, Sr and Nd isotopes in Antarctic deep ice cores, previous studies suggested that Southern South America (SSA) was an important source of dust in Antarctic ice during both glacial and interglacial periods, with negligible contributions from Australian mineral dust. Here we present the first Pb isotopic evidence that dust from Eastern Australia could be an important source of Antarctic dust between 300 kyr BP and 600 kry BP.

  14. Repeated sensory contact with aggressive mice rapidly leads to an anticipatory increase in core body temperature and physical activity that precedes the onset of aversive responding.

    PubMed

    Pardon, Marie-Christine; Kendall, David A; Pérez-Diaz, Fernando; Duxon, Mark S; Marsden, Charles A

    2004-08-01

    The present study investigated whether the 'psychological threat' induced by sensory contact with an aggressive conspecific would be a sufficient factor in inducing behavioural and physiological disturbances. Repeated sensory contact with an aggressive mouse (social threat) in a partitioned cage was compared with repeated exposure to a novel partitioned cage in male NMRI mice. We first examined parameters of stress responsiveness (body weight, plasma corticosterone levels, frequency of self-grooming and defecation). The temperature and physical activity responses to stress were also recorded during and after the 4 weeks of stress using radiotelemetry. Finally, cognitivo-emotional performance was assessed after acute stress and 2 and 4 weeks of stress by measuring decision making, sequential alternation performance and behaviour in the elevated T-maze. Social threat had a greater impact than novel cage exposure on most parameters of stress responsiveness, although mice did not habituate to either stressor. Social threat rapidly led to an anticipatory rise in core body temperature and physical activity before the scheduled stress sessions. Such anticipation developed within the first week and persisted for 9 days after ending the stress procedure. Some memory impairment in the sequential alternation test was found in stressed mice, independent of the stressor. After 4 weeks of stress, inhibitory avoidance in the elevated T-maze was enhanced in socially stressed mice and reduced in novel cage mice. The sustained anticipation of stress in the social threat group preceded aversive responding. It remains to be established whether anticipation contributes to the development of aversive responses.

  15. Bifunctional polydopamine@Fe3O4 core-shell nanoparticles for electrochemical determination of lead(II) and cadmium(II).

    PubMed

    Song, Qian; Li, Maoguo; Huang, Li; Wu, Qikang; Zhou, Yunyou; Wang, Yinling

    2013-07-17

    The present paper has focused on the potential application of the bifunctional polydopamine@Fe3O4 core-shell nanoparticles for development of a simple, stable and highly selective electrochemical method for metal ions monitoring in real samples. The electrochemical method is based on electrochemical preconcentration/reduction of metal ions onto a polydopamine@Fe3O4 modified magnetic glassy carbon electrode at -1.1 V (versus SCE) in 0.1 M pH 5.0 acetate solution containing Pb(2+) and Cd(2+) during 160 s, followed by subsequent anodic stripping. The proposed method has been demonstrated highly selective and sensitive detection of Pb(2+) and Cd(2+), with the calculated detection limits of 1.4×10(-11)M and 9.2×10(-11) M. Under the optimized conditions, the square wave anodic stripping voltammetry response of the modified electrode to Pb(2+) (or Cd(2+)) shows a linear concentration range of 5.0-600 nM (or 20-590 nM) with a correlation coefficient of 0.997 (or 0.994). Further, the proposed method has been performed to successfully detect Pb(2+) and Cd(2+) in aqueous effluent.

  16. Radiation Characterization Summary: ACRR Polyethylene-Lead-Graphite (PLG) Bucket Located in the Central Cavity on the 32-Inch Pedestal at the Core Centerline (ACRR-PLG-CC-32-cl).

    SciTech Connect

    Parma, Edward J.,; Vehar, David W.; Lippert, Lance L.; Griffin, Patrick J.; Naranjo, Gerald E.; Luker, Spencer M.

    2015-06-01

    This document presents the facility-recommended characterization of the neutron, prompt gamma-ray, and delayed gamma-ray radiation fields in the Annular Core Research Reactor (ACRR) for the polyethylene-lead-graphite (PLG) bucket in the central cavity on the 32-inch pedestal at the core centerline. The designation for this environment is ACRR-PLG-CC-32-cl. The neutron, prompt gamma-ray, and delayed gamma-ray energy spectra, uncertainties, and covariance matrices are presented as well as radial and axial neutron and gamma-ray fluence profiles within the experiment area of the bucket. Recommended constants are given to facilitate the conversion of various dosimetry readings into radiation metrics desired by experimenters. Representative pulse operations are presented with conversion examples. Acknowledgements The authors wish to thank the Annular Core Research Reactor staff and the Radiation Metrology Laboratory staff for their support of this work. Also thanks to David Ames for his assistance in running MCNP on the Sandia parallel machines.

  17. Lightweight rotor design by optimal spar cap offset

    NASA Astrophysics Data System (ADS)

    Croce, A.; Sartori, L.; Lunghini, M. S.; Clozza, L.; Bortolotti, P.; Bottasso, C. L.

    2016-09-01

    Bend-twist coupling behavior is induced in a blade by displacing the suction side spar cap towards the leading edge, and the pressure side one in the opposite direction. Additional couplings are introduced by rotating the spar cap fibers. The structural configuration of the blade is optimized using an automated design environment. The resulting blade shows significant benefits in terms of mass and loads when compared to the baseline uncoupled one. Finally, the lightweight design concept is used to increase the rotor size, resulting in a larger energy yield for the same hub loads.

  18. PI3K-PTEN dysregulation leads to mTOR-driven upregulation of the core clock gene BMAL1 in normal and malignant epithelial cells.

    PubMed

    Matsumoto, Camila S; Almeida, Luciana O; Guimarães, Douglas M; Martins, Manoela D; Papagerakis, Petros; Papagerakis, Silvana; Leopoldino, Andreia M; Castilho, Rogerio M; Squarize, Cristiane H

    2016-07-05

    Dysfunctional clock signaling is observed in a variety of pathological conditions. Many members of the clock gene family are upregulated in tumor cells. Here, we explored the consequences of a commonly disrupted signaling pathway in head and neck cancer on the regulation of circadian clock genes. PTEN is a key molecular controller of the PI3K signaling, and loss of PTEN function is often observed in a variety of cancers. Our main goal was to determine whether PTEN regulates circadian clock signaling. We found that oxidation-driven loss of PTEN function resulted in the activation of mTOR signaling and activation of the core clock protein BMAL1 (also known as ARNTL). The PTEN-induced BMAL1 upregulation was further confirmed using small interference RNA targeting PTEN, and in vivo conditional depletion of PTEN from the epidermis. We observed that PTEN-driven accumulation of BMAL1 was mTOR-mediated and that administration of Rapamycin, a specific mTOR inhibitor, resulted in in vivo rescue of normal levels of BMAL1. Accumulation of BMAL1 by deletion of PER2, a Period family gene, was also rescued upon in vivo administration of mTOR inhibitor. Notably, BMAL1 regulation requires mTOR regulatory protein Raptor and Rictor. These findings indicate that mTORC1 and mTORC2 complex plays a critical role in controlling BMAL1, establishing a connection between PI3K signaling and the regulation of circadian rhythm, ultimately resulting in deregulated BMAL1 in tumor cells with disrupted PI3K signaling.

  19. From Blogs to Bottle Caps

    ERIC Educational Resources Information Center

    Edinger, Ted

    2012-01-01

    There is a wonderful community of art educators connecting a once-isolated profession through blogging. Art educators around the world are sharing ideas and communicating with their peers through this amazing resource. In this article, the author describes the bottle cap mural at Tulip Grove Elementary School which was inspired by this exchange of…

  20. CAP Self-Inventory Cards.

    ERIC Educational Resources Information Center

    Ohio State Univ., Columbus. National Center for Research in Vocational Education.

    This booklet of Self-Inventory Cards is one of the 14 components of the Career Alert Planning (CAP) program (see note), a set of individualized materials designed to help participants find out about themselves and about the kind of work for which they are suited. In this program, participants become acquainted with occupations that are…

  1. From Blogs to Bottle Caps

    ERIC Educational Resources Information Center

    Edinger, Ted

    2012-01-01

    There is a wonderful community of art educators connecting a once-isolated profession through blogging. Art educators around the world are sharing ideas and communicating with their peers through this amazing resource. In this article, the author describes the bottle cap mural at Tulip Grove Elementary School which was inspired by this exchange of…

  2. Ultrastable BSA-capped gold nanoclusters with a polymer-like shielding layer against reactive oxygen species in living cells

    NASA Astrophysics Data System (ADS)

    Zhou, Wenjuan; Cao, Yuqing; Sui, Dandan; Guan, Weijiang; Lu, Chao; Xie, Jianping

    2016-05-01

    The prevalence of reactive oxygen species (ROS) production and the enzyme-containing intracellular environment could lead to the fluorescence quenching of bovine serum albumin (BSA)-capped gold nanoclusters (AuNCs). Here we report an efficient strategy to address this issue, where a polymer-like shielding layer is designed to wrap around the Au core to significantly improve the stability of AuNCs against ROS and protease degradation. The key of our design is to covalently incorporate a thiolated AuNC into the BSA-AuNC via carbodiimide-activated coupling, leading to the formation of a AuNC pair inside the cross-linked BSA molecule. The as-designed paired AuNCs in BSA (or BSA-p-AuNCs for short) show improved performances in living cells.The prevalence of reactive oxygen species (ROS) production and the enzyme-containing intracellular environment could lead to the fluorescence quenching of bovine serum albumin (BSA)-capped gold nanoclusters (AuNCs). Here we report an efficient strategy to address this issue, where a polymer-like shielding layer is designed to wrap around the Au core to significantly improve the stability of AuNCs against ROS and protease degradation. The key of our design is to covalently incorporate a thiolated AuNC into the BSA-AuNC via carbodiimide-activated coupling, leading to the formation of a AuNC pair inside the cross-linked BSA molecule. The as-designed paired AuNCs in BSA (or BSA-p-AuNCs for short) show improved performances in living cells. Electronic supplementary information (ESI) available: Detailed experimental materials, apparatus, experimental procedures and characterization data. See DOI: 10.1039/c6nr02178f

  3. Functional end-capped conducting poly (3,4-ethylenedioxythiophene)

    NASA Astrophysics Data System (ADS)

    Sabatini, V.; Farina, H.; Ortenzi, Marco A.

    2016-05-01

    Methacrylate-terminated Poly(3,4-Ethylenedioxythiophene) (PEDOT) polymers with controlled degree of polymerization were successfully prepared by direct oxidative polycondensation between Ethylenedioxythiophene (EDOT) and a cross-linkable methacrylate end-capper monomer, obtained via Friedel Crafts acylation starting from EDOT and Methacryloyl chloride. The new polymer was synthesized in order to overcome the well-known technical problems of PEDOT, i.e. difficult processability and patterning, due to its poor solubility in common organic and inorganic solvents. The chemical structure and the degree of polymerization of the end-capped polymers were determined by 1H NMR spectra. A new synthesis of Methacrylate end-capped PEDOT with controlled degree of polymerization, soluble in common organic and chlorinated solvents and with improved conductivity, 210 S/cm, was performed. This method includes: direct oxidative polycondensation of 3,4-Ethylenedioxythiophene (EDOT) in the presence of a cross-linkable end-capper, i.e. Methacrylate end-capped EDOT prepared via Friedel Crafts acylation with Methacryloyl chloride and oxidant species, i.e. ferric sulfate. Furthermore, the oxidative polycondensation of EDOT monomer and Methacrylate end-capped EDOT in the presence of Sulfonated Polyethersulfone (SPES)- characterized by different degree of Sulfonation (DS)- as dopant agent was performed, leading to functional end-capped conducting PEDOT, easy to process and pattern, with conductivity of 210 S/cm, 50 S/cm higher than the one of commercial PEDOT.

  4. NMR structural characterization of the N-terminal domain of the adenylyl cyclase-associated protein (CAP) from Dictyostelium discoideum.

    PubMed

    Mavoungou, Chrystelle; Israel, Lars; Rehm, Till; Ksiazek, Dorota; Krajewski, Marcin; Popowicz, Grzegorz; Noegel, Angelika A; Schleicher, Michael; Holak, Tad A

    2004-05-01

    Cyclase-associated proteins (CAPs) are highly conserved, ubiquitous actin binding proteins that are involved in microfilament reorganization. The N-termini of CAPs play a role in Ras signaling and bind adenylyl cyclase; the C-termini bind to G-actin. We report here the NMR characterization of the amino-terminal domain of CAP from Dictyostelium discoideum (CAP(1-226)). NMR data, including the steady state (1)H-(15)N heteronuclear NOE experiments, indicate that the first 50 N-terminal residues are unstructured and that this highly flexible serine-rich fragment is followed by a stable, folded core starting at Ser 51. The NMR structure of the folded core is an alpha-helix bundle composed of six antiparallel helices, in a stark contrast to the recently determined CAP C-terminal domain structure, which is solely built by beta-strands.

  5. Surface mass balance of Greenland mountain glaciers and ice caps

    NASA Astrophysics Data System (ADS)

    Benson, R. J.; Box, J. E.; Bromwich, D. H.; Wahr, J. M.

    2009-12-01

    Mountain glaciers and ice caps contribute roughly half of eustatic sea-level rise. Greenland has thousands of small mountain glaciers and several ice caps > 1000 sq. km that have not been included in previous mass balance calculations. To include small glaciers and ice caps in our study, we use Polar WRF, a next-generation regional climate data assimilation model is run at grid resolution less than 10 km. WRF provides surface mass balance data at sufficiently high resolution to resolve not only the narrow ice sheet ablation zone, but provides information useful in downscaling melt and accumulation rates on mountain glaciers and ice caps. In this study, we refine Polar WRF to simulate a realistic surface energy budget. Surface melting is calculated in-line from surface energy budget closure. Blowing snow sublimation is computed in-line. Melt water re-freeze is calculated using a revised scheme. Our results are compared with NASA's Gravity Recovery and Climate Experiment (GRACE) and associated error is calculated on a regional and local scale with validation from automated weather stations (AWS), snow pits and ice core data from various regions along the Greenland ice sheet.

  6. Catastrophic antiphospholipid syndrome (CAPS): update from the 'CAPS Registry'.

    PubMed

    Cervera, R

    2010-04-01

    Although less than 1% of patients with the antiphospholipid syndrome (APS) develop the catastrophic variant, its potentially lethal outcome emphasizes its importance in clinical medicine today. However, the rarity of this variant makes it extraordinarily difficult to study in any systematic way. In order to put together all of the published case reports as well as the new diagnosed cases from all over the world, an international registry of patients with catastrophic APS (CAPS Registry) was created in 2000 by the European Forum on Antiphospholipid Antibodies (see http://www.med.ub.es/MIMMUN/FORUM/CAPS.HTM). Currently, it documents the entire clinical, laboratory and therapeutic data of more than 300 patients whose data has been fully registered.

  7. Tip cap for a rotor blade

    NASA Technical Reports Server (NTRS)

    Kofel, W. K.; Tuley, E. N.; Gay, C. H., Jr.; Troeger, R. E.; Sterman, A. P. (Inventor)

    1983-01-01

    A replaceable tip cap for attachment to the end of a rotor blade is described. The tip cap includes a plurality of walls defining a compartment which, if desired, can be divided into a plurality of subcompartments. The tip cap can include inlet and outlet holes in walls thereof to permit fluid communication of a cooling fluid there through. Abrasive material can be attached with the radially outer wall of the tip cap.

  8. Mammalian CARMIL Inhibits Actin Filament Capping by Capping Protein

    PubMed Central

    Yang, Changsong; Pring, Martin; Wear, Martin A.; Huang, Minzhou; Cooper, John A.; Svitkina, Tatyana M.; Zigmond, Sally H.

    2009-01-01

    Summary Actin polymerization in cells occurs via filament elongation at the barbed end. Proteins that cap the barbed end terminate this elongation. Heterodimeric capping protein (CP) is an abundant and ubiquitous protein that caps the barbed end. We find that the mouse homolog of the adaptor protein CARMIL (mCARMIL) binds CP with high affinity and decreases its affinity for the barbed end. Addition of mCARMIL to cell extracts increases the rate and extent of Arp2/3 or spectrin-actin seed-induced polymerization. In cells, GFP-mCARMIL concentrates in lamellipodia and increases the fraction of cells with large lamellipodia. Decreasing mCARMIL levels by siRNA transfection lowers theF-actin level and slows cell migration through a mechanism that includes decreased lamellipodia protrusion. This phenotype is reversed by full-length mCARMIL but not mCARMIL lacking the domain that binds CP. Thus, mCARMIL is a key regulator of CP and has profound effects on cell behavior. PMID:16054028

  9. 47 CFR 54.675 - Cap.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES (CONTINUED) UNIVERSAL SERVICE Universal Service Support for Health Care Providers General Provisions § 54.675 Cap. (a) Amount of the annual cap. The aggregate annual cap on federal universal service support for health care providers shall...

  10. 47 CFR 54.675 - Cap.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES (CONTINUED) UNIVERSAL SERVICE Universal Service Support for Health Care Providers General Provisions § 54.675 Cap. (a) Amount of the annual cap. The aggregate annual cap on federal universal service support for health care providers shall...

  11. 21 CFR 884.5250 - Cervical cap.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Cervical cap. 884.5250 Section 884.5250 Food and... OBSTETRICAL AND GYNECOLOGICAL DEVICES Obstetrical and Gynecological Therapeutic Devices § 884.5250 Cervical cap. (a) Identification. A cervical cap is a flexible cuplike receptacle that fits over the cervix to...

  12. 21 CFR 884.5250 - Cervical cap.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Cervical cap. 884.5250 Section 884.5250 Food and... OBSTETRICAL AND GYNECOLOGICAL DEVICES Obstetrical and Gynecological Therapeutic Devices § 884.5250 Cervical cap. (a) Identification. A cervical cap is a flexible cuplike receptacle that fits over the cervix to...

  13. 21 CFR 884.5250 - Cervical cap.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Cervical cap. 884.5250 Section 884.5250 Food and... OBSTETRICAL AND GYNECOLOGICAL DEVICES Obstetrical and Gynecological Therapeutic Devices § 884.5250 Cervical cap. (a) Identification. A cervical cap is a flexible cuplike receptacle that fits over the cervix to...

  14. 21 CFR 884.5250 - Cervical cap.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Cervical cap. 884.5250 Section 884.5250 Food and... OBSTETRICAL AND GYNECOLOGICAL DEVICES Obstetrical and Gynecological Therapeutic Devices § 884.5250 Cervical cap. (a) Identification. A cervical cap is a flexible cuplike receptacle that fits over the cervix to...

  15. 21 CFR 884.5250 - Cervical cap.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Cervical cap. 884.5250 Section 884.5250 Food and... OBSTETRICAL AND GYNECOLOGICAL DEVICES Obstetrical and Gynecological Therapeutic Devices § 884.5250 Cervical cap. (a) Identification. A cervical cap is a flexible cuplike receptacle that fits over the cervix...

  16. Dynamic Modeling of an Evapotranspiration Cap

    SciTech Connect

    Jacob J. Jacobson; Steven Piet; Rafael Soto; Gerald Sehlke; Harold Heydt; John Visser

    2005-10-01

    The U.S. Department of Energy is scheduled to design and install hundreds of landfill caps/barriers over the next several decades and these caps will have a design life expectancy of up to 1,000 years. Other landfill caps with 30 year design lifetimes are reaching the end of their original design life; the changes to these caps need to be understood to provide a basis for lifetime extension. Defining the attributes that make a successful cap (one that isolates the waste from the environment) is crucial to these efforts. Because cap systems such as landfill caps are dynamic in nature, it is impossible to understand, monitor, and update lifetime predictions without understanding the dynamics of cap degradation, which is most often due to multiple interdependent factors rather than isolated independent events. In an attempt to understand the dynamics of cap degradation, a computer model using system dynamics is being developed to capture the complex behavior of an evapotranspiration cap. The specific objectives of this project are to capture the dynamic, nonlinear feedback loop structures underlying an evapotranspiration cap and, through computer simulation, gain a better understanding of long-term behavior, influencing factors, and, ultimately, long-term cap performance.

  17. 47 CFR 54.507 - Cap.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... Universal Service Support for Schools and Libraries § 54.507 Cap. (a) Amount of the annual cap. The annual funding cap on federal universal service support for schools and libraries shall be $2.25 billion per... into subsequent funding years for use in the schools and libraries support mechanism in accordance...

  18. CAP2 in cardiac conduction, sudden cardiac death and eye development.

    PubMed

    Field, Jeffrey; Ye, Diana Z; Shinde, Manasi; Liu, Fang; Schillinger, Kurt J; Lu, MinMin; Wang, Tao; Skettini, Michelle; Xiong, Yao; Brice, Angela K; Chung, Daniel C; Patel, Vickas V

    2015-11-30

    Sudden cardiac death kills 180,000 to 450,000 Americans annually, predominantly males. A locus that confers a risk for sudden cardiac death, cardiac conduction disease, and a newly described developmental disorder (6p22 syndrome) is located at 6p22. One gene at 6p22 is CAP2, which encodes a cytoskeletal protein that regulates actin dynamics. To determine the role of CAP2 in vivo, we generated knockout (KO) mice. cap2(-)/cap2(-) males were underrepresented at weaning and ~70% died by 12 weeks of age, but cap2(-)/cap2(-) females survived at close to the expected levels and lived normal life spans. CAP2 knockouts resembled patients with 6p22 syndrome in that mice were smaller and they developed microphthalmia and cardiac disease. The cardiac disease included cardiac conduction disease (CCD) and, after six months of age, dilated cardiomyopathy (DCM), most noticeably in the males. To address the mechanisms underlying these phenotypes, we used Cre-mediated recombination to knock out CAP2 in cardiomyocytes. We found that the mice developed CCD, leading to sudden cardiac death from complete heart block, but no longer developed DCM or the other phenotypes, including sex bias. These studies establish a direct role for CAP2 and actin dynamics in sudden cardiac death and cardiac conduction disease.

  19. CAP2 in cardiac conduction, sudden cardiac death and eye development

    PubMed Central

    Field, Jeffrey; Ye, Diana Z.; Shinde, Manasi; Liu, Fang; Schillinger, Kurt J.; Lu, MinMin; Wang, Tao; Skettini, Michelle; Xiong, Yao; Brice, Angela K.; Chung, Daniel C.; Patel, Vickas V.

    2015-01-01

    Sudden cardiac death kills 180,000 to 450,000 Americans annually, predominantly males. A locus that confers a risk for sudden cardiac death, cardiac conduction disease, and a newly described developmental disorder (6p22 syndrome) is located at 6p22. One gene at 6p22 is CAP2, which encodes a cytoskeletal protein that regulates actin dynamics. To determine the role of CAP2 in vivo, we generated knockout (KO) mice. cap2−/cap2− males were underrepresented at weaning and ~70% died by 12 weeks of age, but cap2−/cap2− females survived at close to the expected levels and lived normal life spans. CAP2 knockouts resembled patients with 6p22 syndrome in that mice were smaller and they developed microphthalmia and cardiac disease. The cardiac disease included cardiac conduction disease (CCD) and, after six months of age, dilated cardiomyopathy (DCM), most noticeably in the males. To address the mechanisms underlying these phenotypes, we used Cre-mediated recombination to knock out CAP2 in cardiomyocytes. We found that the mice developed CCD, leading to sudden cardiac death from complete heart block, but no longer developed DCM or the other phenotypes, including sex bias. These studies establish a direct role for CAP2 and actin dynamics in sudden cardiac death and cardiac conduction disease. PMID:26616005

  20. Upregulated expression of CAP1 is associated with tumor migration and metastasis in hepatocellular carcinoma.

    PubMed

    Liu, Yanhua; Cui, Xiaopeng; Hu, Baoying; Lu, Cuihua; Huang, Xiaodong; Cai, Jing; He, Song; Lv, Liting; Cong, Xia; Liu, Guoliang; Zhang, Yixin; Ni, Runzhou

    2014-03-01

    Hepatocellular carcinoma (HCC) is one of the most common cancers that exhibits high incidences of intrahepatic metastasis and tumor recurrence. Adenylate cyclase-associated protein 1 (CAP1), a protein involved in the regulation of actin filaments, was recently reported to play a role in cell motility and the pathology of pancreatic cancer. In this study, we examined a potential role of CAP1 in HCC progression, and found that CAP1 was overexpressed in HCC specimens compared with adjacent noncancerous liver tissues by Western blot analysis and real-time PCR assay. Further, immunohistochemical analysis in 107 HCC specimens revealed that overexpression of CAP1 was closely correlated only with tumor metastasis, but not with other clinicopathologic parameters. Univariate and multivariate survival analyses showed that CAP1 could be an independent prognostic factor for patients' survival. In addition, immunofluorescent assay demonstrated that CAP1 was colocalized with actin in the leading edge of lamellipodium in HCC cells. Importantly, knocking-down the expression of CAP1 using small interfering RNA (siRNA) targeting CAP1 led to impaired migration of HCC cells. Collectively, our results indicated that upregulated expression of CAP1 might contribute heavily to the metastasis of HCC.

  1. Neuronal Actin Dynamics, Spine Density and Neuronal Dendritic Complexity Are Regulated by CAP2.

    PubMed

    Kumar, Atul; Paeger, Lars; Kosmas, Kosmas; Kloppenburg, Peter; Noegel, Angelika A; Peche, Vivek S

    2016-01-01

    Actin remodeling is crucial for dendritic spine development, morphology and density. CAP2 is a regulator of actin dynamics through sequestering G-actin and severing F-actin. In a mouse model, ablation of CAP2 leads to cardiovascular defects and delayed wound healing. This report investigates the role of CAP2 in the brain using Cap2(gt/gt) mice. Dendritic complexity, the number and morphology of dendritic spines were altered in Cap2(gt/gt) with increased number of excitatory synapses. This was accompanied by increased F-actin content and F-actin accumulation in cultured Cap2(gt/gt) neurons. Moreover, reduced surface GluA1 was observed in mutant neurons under basal condition and after induction of chemical LTP. Additionally, we show an interaction between CAP2 and n-cofilin, presumably mediated through the C-terminal domain of CAP2 and dependent on cofilin Ser3 phosphorylation. In vivo, the consequences of this interaction were altered phosphorylated cofilin levels and formation of cofilin aggregates in the neurons. Thus, our studies identify a novel role of CAP2 in neuronal development and neuronal actin dynamics.

  2. Neuronal Actin Dynamics, Spine Density and Neuronal Dendritic Complexity Are Regulated by CAP2

    PubMed Central

    Kumar, Atul; Paeger, Lars; Kosmas, Kosmas; Kloppenburg, Peter; Noegel, Angelika A.; Peche, Vivek S.

    2016-01-01

    Actin remodeling is crucial for dendritic spine development, morphology and density. CAP2 is a regulator of actin dynamics through sequestering G-actin and severing F-actin. In a mouse model, ablation of CAP2 leads to cardiovascular defects and delayed wound healing. This report investigates the role of CAP2 in the brain using Cap2gt/gt mice. Dendritic complexity, the number and morphology of dendritic spines were altered in Cap2gt/gt with increased number of excitatory synapses. This was accompanied by increased F-actin content and F-actin accumulation in cultured Cap2gt/gt neurons. Moreover, reduced surface GluA1 was observed in mutant neurons under basal condition and after induction of chemical LTP. Additionally, we show an interaction between CAP2 and n-cofilin, presumably mediated through the C-terminal domain of CAP2 and dependent on cofilin Ser3 phosphorylation. In vivo, the consequences of this interaction were altered phosphorylated cofilin levels and formation of cofilin aggregates in the neurons. Thus, our studies identify a novel role of CAP2 in neuronal development and neuronal actin dynamics. PMID:27507934

  3. Polar cap hot patches: Enhanced density structures different from the classical patches in the ionosphere

    NASA Astrophysics Data System (ADS)

    Zhang, Q.-H.; Ma, Y.-Z.; Jayachandran, P. T.; Moen, J.; Lockwood, M.; Zhang, Y.-L.; Foster, J. C.; Zhang, S.-R.; Wang, Y.; Themens, D. R.; Zhang, B.-C.; Xing, Z. Y.

    2017-08-01

    Based on in situ and ground-based observations, a new type of "polar cap hot patch" has been identified that is different from the classical polar cap enhanced density structure (cold patches). Comparing with the classical polar cap patches, which are transported from the dayside sunlit region with dense and cold plasma, the polar cap hot patches are associated with particle precipitations (therefore field-aligned currents), ion upflows, and flow shears. The hot patches may have the same order of density enhancement as classical patches in the topside ionosphere, suggesting that the hot patches may be produced by transported photoionization plasma into flow channels. Within the flow channels, the hot patches have low-energy particle precipitation and/or ion upflows associated with field-aligned currents and flow shears. Corresponding Global Navigation Satellite System (GNSS) signal scintillation measurements indicate that hot patches may produce slightly stronger radio signal scintillation in the polar cap region than classical patches. A new type of polar cap patches, "polar cap hot patches," is identified to differentiate enhanced density structures from classical patches. Hot patches are associated with particle precipitations, ion upflows, field-aligned currents, and shear flows in the polar cap. Hot patches may lead to slightly stronger ionospheric scintillations of GNSS signals in the polar cap region than classical patches.

  4. Condensin II Subunit dCAP-D3 Restricts Retrotransposon Mobilization in Drosophila Somatic Cells

    PubMed Central

    Schuster, Andrew T.; Sarvepalli, Kavitha; Murphy, Eain A.; Longworth, Michelle S.

    2013-01-01

    Retrotransposon sequences are positioned throughout the genome of almost every eukaryote that has been sequenced. As mobilization of these elements can have detrimental effects on the transcriptional regulation and stability of an organism's genome, most organisms have evolved mechanisms to repress their movement. Here, we identify a novel role for the Drosophila melanogaster Condensin II subunit, dCAP-D3 in preventing the mobilization of retrotransposons located in somatic cell euchromatin. dCAP-D3 regulates transcription of euchromatic gene clusters which contain or are proximal to retrotransposon sequence. ChIP experiments demonstrate that dCAP-D3 binds to these loci and is important for maintaining a repressed chromatin structure within the boundaries of the retrotransposon and for repressing retrotransposon transcription. We show that dCAP-D3 prevents accumulation of double stranded DNA breaks within retrotransposon sequence, and decreased dCAP-D3 levels leads to a precise loss of retrotransposon sequence at some dCAP-D3 regulated gene clusters and a gain of sequence elsewhere in the genome. Homologous chromosomes exhibit high levels of pairing in Drosophila somatic cells, and our FISH analyses demonstrate that retrotransposon-containing euchromatic loci are regions which are actually less paired than euchromatic regions devoid of retrotransposon sequences. Decreased dCAP-D3 expression increases pairing of homologous retrotransposon-containing loci in tissue culture cells. We propose that the combined effects of dCAP-D3 deficiency on double strand break levels, chromatin structure, transcription and pairing at retrotransposon-containing loci may lead to 1) higher levels of homologous recombination between repeats flanking retrotransposons in dCAP-D3 deficient cells and 2) increased retrotransposition. These findings identify a novel role for the anti-pairing activities of dCAP-D3/Condensin II and uncover a new way in which dCAP-D3/Condensin II influences local

  5. Condensin II subunit dCAP-D3 restricts retrotransposon mobilization in Drosophila somatic cells.

    PubMed

    Schuster, Andrew T; Sarvepalli, Kavitha; Murphy, Eain A; Longworth, Michelle S

    2013-10-01

    Retrotransposon sequences are positioned throughout the genome of almost every eukaryote that has been sequenced. As mobilization of these elements can have detrimental effects on the transcriptional regulation and stability of an organism's genome, most organisms have evolved mechanisms to repress their movement. Here, we identify a novel role for the Drosophila melanogaster Condensin II subunit, dCAP-D3 in preventing the mobilization of retrotransposons located in somatic cell euchromatin. dCAP-D3 regulates transcription of euchromatic gene clusters which contain or are proximal to retrotransposon sequence. ChIP experiments demonstrate that dCAP-D3 binds to these loci and is important for maintaining a repressed chromatin structure within the boundaries of the retrotransposon and for repressing retrotransposon transcription. We show that dCAP-D3 prevents accumulation of double stranded DNA breaks within retrotransposon sequence, and decreased dCAP-D3 levels leads to a precise loss of retrotransposon sequence at some dCAP-D3 regulated gene clusters and a gain of sequence elsewhere in the genome. Homologous chromosomes exhibit high levels of pairing in Drosophila somatic cells, and our FISH analyses demonstrate that retrotransposon-containing euchromatic loci are regions which are actually less paired than euchromatic regions devoid of retrotransposon sequences. Decreased dCAP-D3 expression increases pairing of homologous retrotransposon-containing loci in tissue culture cells. We propose that the combined effects of dCAP-D3 deficiency on double strand break levels, chromatin structure, transcription and pairing at retrotransposon-containing loci may lead to 1) higher levels of homologous recombination between repeats flanking retrotransposons in dCAP-D3 deficient cells and 2) increased retrotransposition. These findings identify a novel role for the anti-pairing activities of dCAP-D3/Condensin II and uncover a new way in which dCAP-D3/Condensin II influences local

  6. Addition polyimide end cap study

    NASA Technical Reports Server (NTRS)

    St.clair, T. L.

    1980-01-01

    The characterization of addition polyimides with various end caps for adhesive applications at 120-250 C environments is discussed. Oligometric polyimides were prepared from 3,3',4,4'-benzophenone tetracarboxylic dianhydride and 3,3'-methylenedianiline which were end-capped with functionally reactive moities which cause crosslinking when the oligomers are heated to 200-400 C. The syntheses of the oligomers are outlined. The thermolysis of the oligomers was studied by differential scanning calorimetry and the resulting polymers were characterized by differential thermal analysis and adhesive performance. The adhesive data include lap shear strengths on titanium 6-4 adherends both before and after aging for 1000 hours at 121 C and/or 232 C.

  7. Nanosized (mu12-Pt)Pd164-xPtx(CO)72(PPh3)20 (x approximately 7) containing Pt-centered four-shell 165-atom Pd-Pt core with unprecedented intershell bridging carbonyl ligands: comparative analysis of icosahedral shell-growth patterns with geometrically related Pd145(CO)x(PEt3)30 (x approximately 60) containing capped three-shell Pd145 core.

    PubMed

    Mednikov, Evgueni G; Jewell, Matthew C; Dahl, Lawrence F

    2007-09-19

    Presented herein are the preparation and crystallographic/microanalytical/magnetic/spectroscopic characterization of the Pt-centered four-shell 165-atom Pd-Pt cluster, (mu(12)-Pt)Pd(164-x)Pt(x)(CO)(72)(PPh(3))(20) (x approximately 7), 1, that replaces the geometrically related capped three-shell icosahedral Pd(145) cluster, Pd(145)(CO)(x)(PEt(3))(30) (x approximately 60), 2, as the largest crystallographically determined discrete transition metal cluster with direct metal-metal bonding. A detailed comparison of their shell-growth patterns gives rise to important stereochemical implications concerning completely unexpected structural dissimilarities as well as similarities and provides new insight concerning possible synthetic approaches for generation of multi-shell metal clusters. 1 was reproducibly prepared in small yields (<10%) from the reaction of Pd(10)(CO)(12)(PPh(3))(6) with Pt(CO)(2)(PPh(3))(2). Its 165-atom metal-core geometry and 20 PPh(3) and 72 CO ligands were established from a low-temperature (100 K) CCD X-ray diffraction study. The well-determined crystal structure is attributed largely to 1 possessing cubic T(h) (2/m3) site symmetry, which is the highest crystallographic subgroup of the noncrystallographic pseudo-icosahedral I(h) (2/m35) symmetry. The "full" four-shell Pd-Pt anatomy of 1 consists of: (a) shell 1 with the centered (mu(12)-Pt) atom encapsulated by the 12-atom icosahedral Pt(x)Pd(12-x) cage, x = 1.2(3); (b) shell 2 with the 42-atom nu(2) icosahedral Pt(x)Pd(42-x) cage, x = 3.5(5); (c) shell 3 with the anti-Mackay 60-atom semi-regular rhombicosidodecahedral Pt(x)Pd(60-x) cage, x = 2.2(6); (d) shell 4 with the 50-atom nu(2) pentagonal dodecahedral Pd(50) cage. The total number of crystallographically estimated Pt atoms, 8 +/- 3, which was obtained from least-squares (Pt(x)/Pd(1-x))-occupancy analysis of the X-ray data that conclusively revealed the central atom to be pure Pt (occupancy factor, x = 1.00(3)), is fortuitously in agreement

  8. Microscopic reversal behavior of magnetically capped nanospheres

    SciTech Connect

    Guenther, C. M.; Pfau, B.; Eisebitt, S.; Hellwig, O.; Menzel, A.; Radu, F.; Makarov, D.; Albrecht, M.; Goncharov, A.; Schrefl, T.; Schlotter, W. F.; Rick, R.; Luening, J.

    2010-02-01

    The magnetic switching behavior of Co/Pd multilayer-capped nanospheres is investigated by x-ray spectro-holography. Images of the magnetic state of individual nanocaps are recorded as a function of externally applied magnetic field and the angle under which the field is applied, pertaining to magnetic data storage applications with patterned, tilted, and perpendicular storage media. Dispersed nanospheres with different coverage in the submonolayer regime are investigated simultaneously in a multiplexed experiment. In clustered nanosphere arrangements, we find that individual switching events are influenced by dipolar magnetostatic interactions. Micromagnetic simulations of the switching behavior complement the experimental observations, corroborating the influence of thermal activation processes and magnetostatic interactions in this system. Such magnetostatic interactions could lead to undesired cross-talk between bits in ultrahigh-density magnetic recording applications.

  9. Phytoremediation -- a practical capping alternative

    SciTech Connect

    Beath, J.M.; Peak, M.J.

    1997-12-31

    Much literature has been devoted recently to the use of various plant species for the uptake of heavy metals and organic contaminants. Other uses for plants as part of the remediation process are growing in perceived effectiveness. Consequently, this paper deals with two other equally important potential uses of plants to address environmental problems that are just now evolving to the field trial stage: the use of plants to remediate organic pollutants; and the use of plants to control the rainfall-driven leaching of contaminants and the subsequent delivery to underlying groundwater. The traditional Resource Conservation and Recovery Act (RCRA) approach to capping landfills will be contrasted with the potential benefits of using plants that can balance incoming rainfall with evapotranspiration, as well as plants which can act on organic constituents in soil or sludge by either uptake or by promoting microbial activity in soil. This paper compares traditional RCRA capping costs to those for a phytoremediation capping alternative, whose benefits include significantly lower implementation cost and continued remediation. This paper discusses important elements of a successful approach to phytoremediation including: species selection, implementation techniques, cost-efficient monitoring, regulatory aspects, project timing, and realistic expectations.

  10. Benzonorbornadiene end caps for PMR resins

    NASA Technical Reports Server (NTRS)

    Panigot, Michael J.; Waters, John F.; Varde, Uday; Sutter, James K.; Sukenik, Chaim N.

    1992-01-01

    Several ortho-disubstituted benzonorbornadiene derivatives are described. These molecules contain acid, ester, or anhydride functionality permitting their use as end caps in PMR (polymerization of monomer reactants) polyimide systems. The replacement of the currently used norbornenyl end caps with benzonorbornadienyl end caps affords resins of increased aromatic content. It also allows evaluation of some mechanistic aspects of PMR cross-linking. Initial testing of N-phenylimide model compounds and of actual resin formulations using the benzonorbornadienyl end cap reveals that they undergo efficient thermal crosslinking to give oligomers with physical properties and thermal stability comparable to commercial norbornene-end-capped PMR systems.

  11. Little Ice Age Fluctuations of Quelccaya Ice Cap, Peru

    NASA Astrophysics Data System (ADS)

    Stroup, J. S.; Kelly, M. A.; Lowell, T.

    2009-12-01

    A record of the past extents of Quelccaya Ice Cap (QIC) provides valuable information about tropical climate change from late glacial to recent time. Here, we examine the timing and regional significance of fluctuations of QIC during the Little Ice Age (LIA; ~1300-1850 AD). One prominent set of moraines, known as the Huancane I moraines, is located ~1 km from the present-day western ice cap margin and provides a near-continuous outline of the most recent advance of QIC. This moraine set was radiocarbon dated (~298 ± 134 and 831 ± 87 yr BP) by Mercer and Palacios (1977) and presented as some of the first evidence for cooling in the tropics during the Little Ice Age. Recent field investigations in the QIC region focused on refining the chronology of the Huancane I moraines. In 2008, new stratigraphic sections exposed by local lake-flooding events revealed multiple layers of peat within the Huancane I moraines. In both 2008 and 2009, samples were obtained for 10Be dating of boulders on Huancane I moraines. A combination of radiocarbon and 10Be ages indicate that the Huancane I moraines were deposited by ice cap expansion after ~3800 yr BP and likely by multiple advances at approximately 1000, 600, 400, and 200 yr BP. Radiocarbon and 10Be chronologies of the Huancane I moraines are compared with the Quelccaya ice core records (Thompson et al., 1985; 1986; 2006). Accumulation data from the ice core records are interpreted to indicate a significant wet period at ~1500-1700 AD followed by a significant drought at ~1720-1860 AD. We examine ice marginal fluctuations during these times to determine influence of such events on the ice cap extent.

  12. Quantum dot capped magnetite nanorings as high performance nanoprobe for multiphoton fluorescence and magnetic resonance imaging.

    PubMed

    Fan, Hai-Ming; Olivo, Malini; Shuter, Borys; Yi, Jia-Bao; Bhuvaneswari, Ramaswamy; Tan, Hui-Ru; Xing, Gui-Chuan; Ng, Cheng-Teng; Liu, Lei; Lucky, Sasidharan S; Bay, Boon-Huat; Ding, Jun

    2010-10-27

    In the present study, quantum dot (QD) capped magnetite nanorings (NRs) with a high luminescence and magnetic vortex core have been successfully developed as a new class of magnetic-fluorescent nanoprobe. Through electrostatic interaction, cationic polyethylenimine (PEI) capped QD have been firmly graft into negatively charged magnetite NRs modified with citric acid on the surface. The obtained biocompatible multicolor QD capped magnetite NRs exhibit a much stronger magnetic resonance (MR) T2* effect where the r2* relaxivity and r2*/r1 ratio are 4 times and 110 times respectively larger than those of a commercial superparamagnetic iron oxide. The multiphoton fluorescence imaging and cell uptake of QD capped magnetite NRs are also demonstrated using MGH bladder cancer cells. In particular, these QD capped magnetite NRs can escape from endosomes and be released into the cytoplasm. The obtained results from these exploratory experiments suggest that the cell-penetrating QD capped magnetite NRs could be an excellent dual-modality nanoprobe for intracellular imaging and therapeutic applications. This work has shown great potential of the magnetic vortex core based multifunctional nanoparticle as a high performance nanoprobe for biomedical applications.

  13. Composite Cores

    NASA Technical Reports Server (NTRS)

    1990-01-01

    Spang & Company's new configuration of converter transformer cores is a composite of gapped and ungapped cores assembled together in concentric relationship. The net effect of the composite design is to combine the protection from saturation offered by the gapped core with the lower magnetizing requirement of the ungapped core. The uncut core functions under normal operating conditions and the cut core takes over during abnormal operation to prevent power surges and their potentially destructive effect on transistors. Principal customers are aerospace and defense manufacturers. Cores also have applicability in commercial products where precise power regulation is required, as in the power supplies for large mainframe computers.

  14. Crystal chemistry of layered structures formed by linear rigid silyl-capped molecules.

    PubMed

    Lumpi, Daniel; Kautny, Paul; Stöger, Berthold; Fröhlich, Johannes

    2015-09-01

    The crystallization behavior of methylthio- or methylsulfonyl-containing spacer extended Z,Z-bis-ene-yne molecules capped with trimethylsilyl groups obtained by (tandem) thiophene ring fragmentation and of two non-spacer extended analogs were investigated. The rigid and linear molecules generally crystallized in layers whereby the flexibility of the layer interfaces formed by the silyl groups leads to a remarkably rich crystal chemistry. The molecules with benzene and thiophene spacers both crystallized with C2/c symmetry and can be considered as merotypes. Increasing the steric bulk of the core by introduction of ethylenedioxythiophene (EDOT) gave a structure incommensurately modulated in the [010] direction. Further increase of steric demand in the case of a dimethoxythiophene restored periodicity along [010] but resulted in a doubling of the c vector. Two different polytypes were observed, which feature geometrically different layer interfaces (non-OD, order-disorder, polytypes), one with a high stacking fault probability. Oxidation of the methylthio groups of the benzene-based molecule to methylsulfonyl groups led to three polymorphs (two temperature-dependent), which were analyzed by Hirshfeld surface d e/d i fingerprint plots. The analogously oxidized EDOT-based molecule crystallized as systematic twins owing to its OD polytypism. Shortening of the backbone by removal of the aryl core resulted in an enantiomorphic structure and a further shortening by removal of a methylthio-ene fragment again in a systematically twinned OD polytype.

  15. High Arctic Holocene temperature record from the Agassiz ice cap and Greenland ice sheet evolution.

    PubMed

    Lecavalier, Benoit S; Fisher, David A; Milne, Glenn A; Vinther, Bo M; Tarasov, Lev; Huybrechts, Philippe; Lacelle, Denis; Main, Brittany; Zheng, James; Bourgeois, Jocelyne; Dyke, Arthur S

    2017-06-06

    We present a revised and extended high Arctic air temperature reconstruction from a single proxy that spans the past ∼12,000 y (up to 2009 CE). Our reconstruction from the Agassiz ice cap (Ellesmere Island, Canada) indicates an earlier and warmer Holocene thermal maximum with early Holocene temperatures that are 4-5 °C warmer compared with a previous reconstruction, and regularly exceed contemporary values for a period of ∼3,000 y. Our results show that air temperatures in this region are now at their warmest in the past 6,800-7,800 y, and that the recent rate of temperature change is unprecedented over the entire Holocene. The warmer early Holocene inferred from the Agassiz ice core leads to an estimated ∼1 km of ice thinning in northwest Greenland during the early Holocene using the Camp Century ice core. Ice modeling results show that this large thinning is consistent with our air temperature reconstruction. The modeling results also demonstrate the broader significance of the enhanced warming, with a retreat of the northern ice margin behind its present position in the mid Holocene and a ∼25% increase in total Greenland ice sheet mass loss (∼1.4 m sea-level equivalent) during the last deglaciation, both of which have implications for interpreting geodetic measurements of land uplift and gravity changes in northern Greenland.

  16. Co-Ordination Compounds as Sensitizers for Percussion Cap Compositions

    DTIC Science & Technology

    1949-01-01

    Lead styphnate , unfortunately, makes the finished caps liable to explode en-masse, while barium nitrate promotes muzzle flash in certain guns. V...based on dinitro- diazophenol (D.D.N.P.). Type (a) contains lead styphnate , tetrazene, barium nitrate, calcium silicide, lead peroxide (with or...oxide 16 8 4 3 Sodium dinitrobonzfurazan oxide 16 8 4 3 Barium Styphnate 16 8 4 3 2 1 45. < 3 1 » ; I 5I 5^ I ’s 1 • •o t o

  17. Stability of Barnes Ice Cap, Baffin Island, Canada

    NASA Astrophysics Data System (ADS)

    Gilbert, A.; Flowers, G. E.; Miller, G. H.; Rabus, B.; Gardner, A. S.; Van Wychen, W. D.; Copland, L.; Radic, V.

    2015-12-01

    Barnes Ice Cap is a modern remnant of the Laurentide Ice Sheet, which covered much of North America during the Last Glacial Maximum. Moraine chronology shows that Barnes reached a quasi-equilibrium state about 1000 years ago and has been relatively stable since. The flat and low-elevation bedrock topography under Barnes implies that the accumulation area owes its existence to the ice cap itself. As a "self-sustaining" ice mass, Barnes is expected to be sensitive to climate and/or dynamical changes given the surface-elevation / mass-balance feedback. In this study, we combine historical observations (1960-1980) with new satellite and air-borne data (1995-2010) to drive a mass-balance model coupled to a transient full-Stokes thermo-mechanical model with an adaptive mesh geometry. The model is used to characterize the current state of the ice cap and to investigate its stability as a function of climate and internal ice dynamics. Thermo-mechanically coupled simulations show zones of locally enhanced ice flow that imprint themselves on the shape of the ice-cap. These simulations suggest that an additional heat source, such as refreezing of water at the base of the ice cap, is required to maintain temperate conditions where sliding is known to occur. Modelled dynamics highlight the influence of contrasting viscosities between Pleistocene and Holocene ice that affect the form and flow of the ice cap. On millennial timescales, the internal dynamics of the ice cap may lead to divergent evolution pathways even for a constant climate. Sensitivity experiments reveal that Barnes was in a delicate equilibrium with pre-industrial climate. An increase in air temperature of less than 0.2K or a decrease precipitation of less than 15%, relative to this climate, is enough to push the ice cap into an unstable regime. Based on recent observations of the equilibrium line altitude, Barnes is expected to disappear even with no additional warming.

  18. Holocene history of North Ice Cap, northwestern Greenland

    NASA Astrophysics Data System (ADS)

    Corbett, L. B.; Kelly, M. A.; Osterberg, E. C.; Axford, Y.; Bigl, M.; Roy, E. P.; Thompson, J. T.

    2013-12-01

    Although much research has focused on the past extents of the Greenland Ice Sheet, less is known about the smaller ice caps on Greenland and how they have evolved over time. These small ice caps respond sensitively to summer temperatures and, to a lesser extent, winter precipitation, and provide valuable information about climatic conditions along the Greenland Ice Sheet margins. Here, we investigate the Holocene history of North Ice Cap (76°55'N 68°00'W), located in the Nunatarssuaq region near Thule, northwest Greenland. Our results are based on glacial geomorphic mapping, 10Be dating, and analyses of sediment cores from a glacially fed lake. Fresh, unweathered and unvegetated boulders comprise moraines and drift that mark an extent of North Ice Cap ~25 m outboard of the present ice margin. It is likely that these deposits were formed during late Holocene time and we are currently employing 10Be surface exposure dating to examine this hypothesis. Just outboard of the fresh moraines and drift, boulders and bedrock show significant weathering and are covered with lichen. Based on glacial geomorphic mapping and detailed site investigations, including stone counts, we suggest that the weathered boulders and bedrock were once covered by erosive Greenland Ice Sheet flow from southeast to northwest over the Nunatarssuaq region. Five 10Be ages from the more weathered landscape only 100-200 m outboard of the modern North Ice Cap margin are 52 and 53 ka (bedrock) and 16, 23, and 31 ka (boulders). These ages indicate that recent ice cover has likely been cold-based and non-erosive, failing to remove inherited cosmogenic nuclides from previous periods of exposure, although the youngest boulder may provide a maximum limiting deglaciation age. Sediment cores collected from Delta Sø, a glacially-fed lake ~1.5 km outside of the modern North Ice Cap margin, contain 130 cm of finely laminated sediments overlying coarse sands and glacial till. Radiocarbon ages from just above

  19. LEAD IN CANDLE EMISSIONS

    EPA Science Inventory

    The candle-using public should be made aware that the core of candle wicks may contain lead. Used as a stiffening agent to keep the wick out of the molten wax, lead can be emitted as particulate to the air and then deposited on indoor surfaces. To define the problem, 100 sets of ...

  20. LEAD IN CANDLE EMISSIONS

    EPA Science Inventory

    The candle-using public should be made aware that the core of candle wicks may contain lead. Used as a stiffening agent to keep the wick out of the molten wax, lead can be emitted as particulate to the air and then deposited on indoor surfaces. To define the problem, 100 sets of ...

  1. CAP defines a second signalling pathway required for insulin-stimulated glucose transport.

    PubMed

    Baumann, C A; Ribon, V; Kanzaki, M; Thurmond, D C; Mora, S; Shigematsu, S; Bickel, P E; Pessin, J E; Saltiel, A R

    2000-09-14

    Insulin stimulates the transport of glucose into fat and muscle cells. Although the precise molecular mechanisms involved in this process remain uncertain, insulin initiates its actions by binding to its tyrosine kinase receptor, leading to the phosphorylation of intracellular substrates. One such substrate is the Cbl proto-oncogene product. Cbl is recruited to the insulin receptor by interaction with the adapter protein CAP, through one of three adjacent SH3 domains in the carboxy terminus of CAP. Upon phosphorylation of Cbl, the CAP-Cbl complex dissociates from the insulin receptor and moves to a caveolin-enriched, triton-insoluble membrane fraction. Here, to identify a molecular mechanism underlying this subcellular redistribution, we screened a yeast two-hybrid library using the amino-terminal region of CAP and identified the caveolar protein flotillin. Flotillin forms a ternary complex with CAP and Cbl, directing the localization of the CAP-Cbl complex to a lipid raft subdomain of the plasma membrane. Expression of the N-terminal domain of CAP in 3T3-L1 adipocytes blocks the stimulation of glucose transport by insulin, without affecting signalling events that depend on phosphatidylinositol-3-OH kinase. Thus, localization of the Cbl-CAP complex to lipid rafts generates a pathway that is crucial in the regulation of glucose uptake.

  2. Dynamic sorting of nuclear components into distinct nucleolar caps during transcriptional inhibition.

    PubMed

    Shav-Tal, Yaron; Blechman, Janna; Darzacq, Xavier; Montagna, Cristina; Dye, Billy T; Patton, James G; Singer, Robert H; Zipori, Dov

    2005-05-01

    Nucleolar segregation is observed under some physiological conditions of transcriptional arrest. This process can be mimicked by transcriptional arrest after actinomycin D treatment leading to the segregation of nucleolar components and the formation of unique structures termed nucleolar caps surrounding a central body. These nucleolar caps have been proposed to arise from the segregation of nucleolar components. We show that contrary to prevailing notion, a group of nucleoplasmic proteins, mostly RNA binding proteins, relocalized from the nucleoplasm to a specific nucleolar cap during transcriptional inhibition. For instance, an exclusively nucleoplasmic protein, the splicing factor PSF, localized to nucleolar caps under these conditions. This structure also contained pre-rRNA transcripts, but other caps contained either nucleolar proteins, PML, or Cajal body proteins and in addition nucleolar or Cajal body RNAs. In contrast to the capping of the nucleoplasmic components, nucleolar granular component proteins dispersed into the nucleoplasm, although at least two (p14/ARF and MRP RNA) were retained in the central body. The nucleolar caps are dynamic structures as determined using photobleaching and require energy for their formation. These findings demonstrate that the process of nucleolar segregation and capping involves energy-dependent repositioning of nuclear proteins and RNAs and emphasize the dynamic characteristics of nuclear domain formation in response to cellular stress.

  3. CAP defines a second signalling pathway required for insulin-stimulated glucose transport

    NASA Astrophysics Data System (ADS)

    Baumann, Christian A.; Ribon, Vered; Kanzaki, Makoto; Thurmond, Debbie C.; Mora, Silvia; Shigematsu, Satoshi; Bickel, Perry E.; Pessin, Jeffrey E.; Saltiel, Alan R.

    2000-09-01

    Insulin stimulates the transport of glucose into fat and muscle cells. Although the precise molecular mechanisms involved in this process remain uncertain, insulin initiates its actions by binding to its tyrosine kinase receptor, leading to the phosphorylation of intracellular substrates. One such substrate is the Cbl protooncogene product. Cbl is recruited to the insulin receptor by interaction with the adapter protein CAP, through one of three adjacent SH3 domains in the carboxy terminus of CAP. Upon phosphorylation of Cbl, the CAP-Cbl complex dissociates from the insulin receptor and moves to a caveolin-enriched, triton-insoluble membrane fraction. Here, to identify a molecular mechanism underlying this subcellular redistribution, we screened a yeast two-hybrid library using the amino-terminal region of CAP and identified the caveolar protein flotillin. Flotillin forms a ternary complex with CAP and Cbl, directing the localization of the CAP-Cbl complex to a lipid raft subdomain of the plasma membrane. Expression of the N-terminal domain of CAP in 3T3-L1 adipocytes blocks the stimulation of glucose transport by insulin, without affecting signalling events that depend on phosphatidylinositol-3-OH kinase. Thus, localization of the Cbl-CAP complex to lipid rafts generates a pathway that is crucial in the regulation of glucose uptake.

  4. LEADING WITH LEADING INDICATORS

    SciTech Connect

    PREVETTE, S.S.

    2005-01-27

    This paper documents Fluor Hanford's use of Leading Indicators, management leadership, and statistical methodology in order to improve safe performance of work. By applying these methods, Fluor Hanford achieved a significant reduction in injury rates in 2003 and 2004, and the improvement continues today. The integration of data, leadership, and teamwork pays off with improved safety performance and credibility with the customer. The use of Statistical Process Control, Pareto Charts, and Systems Thinking and their effect on management decisions and employee involvement are discussed. Included are practical examples of choosing leading indicators. A statistically based color coded dashboard presentation system methodology is provided. These tools, management theories and methods, coupled with involved leadership and employee efforts, directly led to significant improvements in worker safety and health, and environmental protection and restoration at one of the nation's largest nuclear cleanup sites.

  5. Seismic explosion sources on an ice cap - Technical considerations

    NASA Astrophysics Data System (ADS)

    Shulgin, Alexey; Thybo, Hans

    2015-03-01

    Controlled source seismic investigation of crustal structure below ice covers is an emerging technique. We have recently conducted an explosive refraction/wide-angle reflection seismic experiment on the ice cap in east-central Greenland. The data-quality is high for all shot points and a full crustal model can be modelled. A crucial challenge for applying the technique is to control the sources. Here, we present data that describe the efficiency of explosive sources in the ice cover. Analysis of the data shows, that the ice cap traps a significant amount of energy, which is observed as a strong ice wave. The ice cap leads to low transmission of energy into the crust such that charges need be larger than in conventional onshore experiments to obtain reliable seismic signals. The strong reflection coefficient at the base of the ice generates strong multiples which may mask for secondary phases. This effect may be crucial for acquisition of reflection seismic profiles on ice caps. Our experience shows that it is essential to use optimum depth for the charges and to seal the boreholes carefully.

  6. Damages Caps in Medical Malpractice Cases

    PubMed Central

    Nelson, Leonard J; Morrisey, Michael A; Kilgore, Meredith L

    2007-01-01

    This article reviews the empirical literature on the effects of damages caps and concludes that the better-designed studies show that damages caps reduce liability insurance premiums. The effects of damages caps on defensive medicine, physicians’ location decisions, and the cost of health care to consumers are less clear. The only study of whether consumers benefit from lower health insurance premiums as a result of damages caps found no impact. Some state courts have based decisions declaring damages caps legislation unconstitutional on the lack of evidence of their effectiveness, thereby ignoring the findings of conflicting research studies or discounting their relevance. Although courts should be cautious in rejecting empirical evidence that caps are effective, legislators should consider whether they benefit consumers enough to justify limiting tort recoveries for those most seriously injured by malpractice. PMID:17517115

  7. CAP2 is a regulator of the actin cytoskeleton and its absence changes infiltration of inflammatory cells and contraction of wounds.

    PubMed

    Kosmas, Kosmas; Eskandarnaz, Ali; Khorsandi, Arya B; Kumar, Atul; Ranjan, Rajeev; Eming, Sabine A; Noegel, Angelika A; Peche, Vivek S

    2015-01-01

    Cyclase associated protein (CAP) is a highly conserved protein with roles in actin dynamics and many cellular processes. Two isoforms exist in higher eukaryotes, CAP1 and CAP2. CAP1 is ubiquitously expressed whereas CAP2 shows restricted tissue distribution. In mice, ablation of CAP2 leads to development of cardiomyopathy. CAP2 is expressed in skin. In human skin its expression is increased in wounds. To elucidate the role of CAP2 in skin upon injury, we studied the wound healing in CAP2 deficient mice and found altered wound healing response presumably resulting from reduced levels of α-SMA, decreased macrophage infiltration and slower neovascularization. In vitro cultured Cap2 deficient keratinocytes showed reduced velocity and a delay in scratch closure. The analysis of primary mutant fibroblasts also showed reduced velocity and less contractibility. They had extended protrusions and more focal adhesions. In addition the F-actin content was increased keeping the total actin content unaltered. Mutant fibroblasts furthermore exhibited an altered response during recovery from drug-induced disruption of the actin cytoskeleton. Interestingly, CAP1 was upregulated in knockout unwounded skin and in wounds which might partially compensate for the loss of CAP2. Taken together, our studies reveal a role for CAP2 in wound healing which may be based on its function as a regulator of the actin cytoskeleton.

  8. Mountain Glaciers and Ice Caps

    USGS Publications Warehouse

    Ananichheva, Maria; Arendt, Anthony; Hagen, Jon-Ove; Hock, Regine; Josberger, Edward G.; Moore, R. Dan; Pfeffer, William Tad; Wolken, Gabriel J.

    2011-01-01

    Projections of future rates of mass loss from mountain glaciers and ice caps in the Arctic focus primarily on projections of changes in the surface mass balance. Current models are not yet capable of making realistic forecasts of changes in losses by calving. Surface mass balance models are forced with downscaled output from climate models driven by forcing scenarios that make assumptions about the future rate of growth of atmospheric greenhouse gas concentrations. Thus, mass loss projections vary considerably, depending on the forcing scenario used and the climate model from which climate projections are derived. A new study in which a surface mass balance model is driven by output from ten general circulation models (GCMs) forced by the IPCC (Intergovernmental Panel on Climate Change) A1B emissions scenario yields estimates of total mass loss of between 51 and 136 mm sea-level equivalent (SLE) (or 13% to 36% of current glacier volume) by 2100. This implies that there will still be substantial glacier mass in the Arctic in 2100 and that Arctic mountain glaciers and ice caps will continue to influence global sea-level change well into the 22nd century.

  9. Build-up cap materials for measurement of photon head-scatter factors.

    PubMed

    Weber, L; Nilsson, P; Ahnesjö, A

    1997-10-01

    The suitability of high-Z materials as build-up caps for head-scatter measurements has been investigated. Build-up caps are often used to enable characterization of fields too small for a mini-phantom. We have studied lead and brass build-up caps with sufficiently large wall thicknesses, as compared to the range of contaminating electrons originating in the accelerator head, and compared them with build-up caps made of ionization chamber equivalent materials, i.e. graphite. The results were also compared with measurements taken using square and cylindrical polystyrene mini-phantoms. Field sizes ranging from 3 cm x 3 cm up to 40 cm x 40 cm were studied for nominal photon energies of 4, 6, 10 and 18 MV. The results show that the use of lead and brass build-up caps produces normalized head-scatter data slightly different from graphite build-up caps for large fields at high photon energies. At lower energies, however, no significant differences were found. The intercomparison between the two different plastic mini-phantoms and graphite caps showed no differences.

  10. 21 CFR 888.3000 - Bone cap.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Bone cap. 888.3000 Section 888.3000 Food and Drugs... ORTHOPEDIC DEVICES Prosthetic Devices § 888.3000 Bone cap. (a) Identification. A bone cap is a mushroom... polyethylene. It is used to cover the severed end of a long bone, such as the humerus or tibia, to control bone...

  11. 21 CFR 888.3000 - Bone cap.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Bone cap. 888.3000 Section 888.3000 Food and Drugs... ORTHOPEDIC DEVICES Prosthetic Devices § 888.3000 Bone cap. (a) Identification. A bone cap is a mushroom... polyethylene. It is used to cover the severed end of a long bone, such as the humerus or tibia, to control bone...

  12. 21 CFR 888.3000 - Bone cap.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Bone cap. 888.3000 Section 888.3000 Food and Drugs... ORTHOPEDIC DEVICES Prosthetic Devices § 888.3000 Bone cap. (a) Identification. A bone cap is a mushroom... polyethylene. It is used to cover the severed end of a long bone, such as the humerus or tibia, to control bone...

  13. 21 CFR 888.3000 - Bone cap.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Bone cap. 888.3000 Section 888.3000 Food and Drugs... ORTHOPEDIC DEVICES Prosthetic Devices § 888.3000 Bone cap. (a) Identification. A bone cap is a mushroom... polyethylene. It is used to cover the severed end of a long bone, such as the humerus or tibia, to control bone...

  14. 21 CFR 888.3000 - Bone cap.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Bone cap. 888.3000 Section 888.3000 Food and Drugs... ORTHOPEDIC DEVICES Prosthetic Devices § 888.3000 Bone cap. (a) Identification. A bone cap is a mushroom... polyethylene. It is used to cover the severed end of a long bone, such as the humerus or tibia, to control bone...

  15. A wireline piston core barrel for sampling cohesionless sand and gravel below the water table

    USGS Publications Warehouse

    Zapico, Michael M.; Vales, Samuel; Cherry, John A.

    1987-01-01

    A coring device has been developed to obtain long and minimally disturbed samples of saturated cohesionless sand and gravel. The coring device, which includes a wireline and piston, was developed specifically for use during hollow-stem auger drilling but it also offers possibilities for cable tool and rotary drilling. The core barrel consists of an inner liner made of inexpensive aluminum or plastic tubing, a piston for core recovery, and an exterior steel housing that protects the liner when the core barrel is driven into the aquifer. The core barrel, which is approximately 1.6m (5.6 feet) long, is advanced ahead of the lead auger by hammering at the surface on drill rods that are attached to the core barrel. After the sampler has been driven 1.5m (5 feet), the drill rods are detached and a wireline is used to hoist the core barrel, with the sample contained in the aluminum or plastic liner, to the surface. A vacuum developed by the piston during the coring operation provides good recovery of both the sediment and aquifer fluids contained in the sediment. In the field the sample tubes can be easily split along their length for on-site inspection or they can be capped with the pore water fluids inside and transported to the laboratory. The cores are 5cm (2 inches) in diameter by 1.5m (5 feet) long. Core acquisition to depths of 35m (115 feet), with a recovery greater than 90 percent, has become routine in University of Waterloo aquifer studies. A large diameter (12.7cm [5 inch]) version has also been used successfully. Nearly continuous sample sequences from sand and gravel aquifers have been obtained for studies of sedimentology, hydraulic conductivity, hydrogeochemistry and microbiology.

  16. Capping and methylation of mRNA by purified recombinant VP4 protein of bluetongue virus

    PubMed Central

    Ramadevi, N.; Burroughs, Nicholas J.; Mertens, Peter P. C.; Jones, Ian M.; Roy, Polly

    1998-01-01

    The core of bluetongue virus (BTV) is a multienzyme complex composed of two major proteins (VP7 and VP3) and three minor proteins (VP1, VP4, and VP6) in addition to the viral genome. The core is transcriptionally active and produces capped mRNA from which all BTV proteins are translated, but the relative role of each core component in the overall reaction process remains unclear. Previously we showed that the 76-kDa VP4 protein possesses guanylyltransferase activity, a necessary part of the RNA capping reaction. Here, through the use of highly purified (>95%) VP4 and synthetic core-like particles containing VP4, we have investigated the extent to which this protein is also responsible for other activities associated with cap formation. We show that VP4 catalyzes the conversion of unmethylated GpppG or in vitro-produced uncapped BTV RNA transcripts to m7GpppGm in the presence of S-adenosyl-l-methionine. Analysis of the methylated products of the reaction by HPLC identified both methyltransferase type 1 and type 2 activities associated with VP4, demonstrating that the complete BTV capping reaction is associated with this one protein. PMID:9811835

  17. A TPM3 mutation causing cap myopathy.

    PubMed

    De Paula, Andre Maues; Franques, Jerome; Fernandez, Carla; Monnier, Nicole; Lunardi, Joel; Pellissier, Jean-François; Figarella-Branger, Dominique; Pouget, Jean

    2009-10-01

    Cap disease is a rare congenital myopathy associated with skeletal malformations and respiratory involvement. Abnormally arranged myofibrils taking the appearance of a "cap" are the morphological hallmark of this entity. We report a case of cap disease concerning a 42-year-old man, without any family history and presenting a p.Arg168His mutation on the TPM3 gene. His first biopsy at 7years had only shown selective type I hypotrophy. Mutations of TPM3 gene have been found in nemaline myopathy, congenital fiber type disproportion, but never before in cap disease.

  18. Predictable removal of anticardiolipin antibody by therapeutic plasma exchange (TPE) in catastrophic antiphospholipid antibody syndrome (CAPS).

    PubMed

    Zar, T; Kaplan, A A

    2008-07-01

    Catastrophic antiphospholipid antibody syndrome (CAPS) is a rare life-threatening variant of antiphospholipid antibody syndrome (APS), with an associated mortality rate of > 50%. Treatment recommendations are aggressive and consist of intravenous heparin, steroids, immunoglobulins and/or therapeutic plasma exchange (TPE). At present, insufficient data exist to make precise recommendations regarding the most effective therapy for CAPS. Accumulating evidence over recent years is encouraging and may lead to future guidelines. We report predictive and effective removal of pathological anticardiolipin antibody (aCL AB) in a patient with CAPS. The case report and discussion provide valuable insight into aCL AB production and its removal by first- order kinetics using TPE.

  19. Synthetic Capped mRNAs for Cap-Specific Photo-Cross-Linking Experiments.

    PubMed

    Kowalska, Joanna; Martin, Franck; Jemielity, Jacek

    2016-01-01

    The 7-methylguanosine triphosphate cap present at the 5' ends of eukaryotic mRNAs plays numerous roles in mRNA expression and metabolism. The identification and studies on cap-binding partners can be significantly advanced using tailored chemical tools such as synthetic cap analogues or RNAs carrying modified cap structures. Here we provide protocols for the production of mRNAs specifically labeled within the 5' cap with a nucleoside capable of being photo-activated, either 6-thioguanosine or 7-methyl-6-thioguanosine, which can be used in photo-cross-linking experiments to identify or characterize cap-binding biomolecules. We also describe a protocol for the cross-linking experiments with capped RNAs to map histone H4 cap-binding pocket.

  20. Cyclase-associated protein 1 (CAP1) promotes cofilin-induced actin dynamics in mammalian nonmuscle cells.

    PubMed

    Bertling, Enni; Hotulainen, Pirta; Mattila, Pieta K; Matilainen, Tanja; Salminen, Marjo; Lappalainen, Pekka

    2004-05-01

    Cyclase-associated proteins (CAPs) are highly conserved actin monomer binding proteins present in all eukaryotes. However, the mechanism by which CAPs contribute to actin dynamics has been elusive. In mammals, the situation is further complicated by the presence of two CAP isoforms whose differences have not been characterized. Here, we show that CAP1 is widely expressed in mouse nonmuscle cells, whereas CAP2 is the predominant isoform in developing striated muscles. In cultured NIH3T3 and B16F1 cells, CAP1 is a highly abundant protein that colocalizes with cofilin-1 to dynamic regions of the cortical actin cytoskeleton. Analysis of CAP1 knockdown cells demonstrated that this protein promotes rapid actin filament depolymerization and is important for cell morphology, migration, and endocytosis. Interestingly, depletion of CAP1 leads to an accumulation of cofilin-1 into abnormal cytoplasmic aggregates and to similar cytoskeletal defects to those seen in cofilin-1 knockdown cells, demonstrating that CAP1 is required for proper subcellular localization and function of ADF/cofilin. Together, these data provide the first direct in vivo evidence that CAP promotes rapid actin dynamics in conjunction with ADF/cofilin and is required for several central cellular processes in mammals.

  1. Autistic-like behavioral phenotypes in a mouse model with copy number variation of the CAPS2/CADPS2 gene.

    PubMed

    Sadakata, Tetsushi; Shinoda, Yo; Oka, Megumi; Sekine, Yukiko; Furuichi, Teiichi

    2013-01-04

    Ca²⁺-dependent activator protein for secretion 2 (CAPS2 or CADPS2) facilitates secretion and trafficking of dense-core vesicles. Recent genome-wide association studies of autism have identified several microdeletions due to copy number variation (CNV) in one of the chromosome 7q31.32 alleles on which the locus for CAPS2 is located in autistic patients. To evaluate the biological significance of reducing CAPS2 copy number, we analyzed CAPS2 heterozygous mice. Our present findings suggest that adequate levels of CAPS2 protein are critical for normal brain development and behavior, and that allelic changes due to CNV may contribute to autistic symptoms in combination with deficits in other autism-associated genes.

  2. The Martian polar caps: Stability and water transport at low obliquities

    NASA Technical Reports Server (NTRS)

    Henderson, B. G.; Jakosky, B. M.

    1992-01-01

    The seasonal cycle of water on Mars is regulated by the two polar caps. In the winter hemisphere, the seasonal CO2 deposits at a temperature near 150 K acts as a cold trap to remove water vapor from the atmosphere. When summer returns, water is pumped back into the atmosphere by a number of mechanisms, including release from the receding CO2 frost, diffusion from the polar regolith, and sublimation from a water-ice residual cap. These processes drive an exchange of water vapor between the polar caps that helps shape the Martian climate. Thus, understanding the behavior of the polar caps is important for interpreting the Martian climate both now and at other epochs. Mars' obliquity undergoes large variations over large time scales. As the obliquity decreases, the poles receive less solar energy so that more CO2 condenses from the atmosphere onto the poles. It has been suggested that permanent CO2 condenses from the atmosphere onto the poles. It has been suggested that permanent CO2 caps might form at the poles in response to a feedback mechanism existing between the polar cap albedo, the CO2 pressure, and the dust storm frequency. The year-round presence of the CO2 deposits would effectively dry out the atmosphere, while diffusion of water from the regolith would be the only source of water vapor to the atmosphere. We have reviewed the CO2 balance at low obliquity taking into account the asymmetries which make the north and south hemispheres different. Our analysis linked with a numerical model of the polar caps leads us to believe that one summertime cap will always lose its CO2 cover during a Martian year, although we cannot predict which cap this will be. We conclude that significant amounts of water vapor will sublime from the exposed cap during summer, and the Martian atmosphere will support an active water cycle even at low obliquity.

  3. The Martian polar caps: Stability and water transport at low obliquities

    NASA Technical Reports Server (NTRS)

    Henderson, B. G.; Jakosky, B. M.

    1992-01-01

    The seasonal cycle of water on Mars is regulated by the two polar caps. In the winter hemisphere, the seasonal CO2 deposits at a temperature near 150 K acts as a cold trap to remove water vapor from the atmosphere. When summer returns, water is pumped back into the atmosphere by a number of mechanisms, including release from the receding CO2 frost, diffusion from the polar regolith, and sublimation from a water-ice residual cap. These processes drive an exchange of water vapor between the polar caps that helps shape the Martian climate. Thus, understanding the behavior of the polar caps is important for interpreting the Martian climate both now and at other epochs. Mars' obliquity undergoes large variations over large time scales. As the obliquity decreases, the poles receive less solar energy so that more CO2 condenses from the atmosphere onto the poles. It has been suggested that permanent CO2 condenses from the atmosphere onto the poles. It has been suggested that permanent CO2 caps might form at the poles in response to a feedback mechanism existing between the polar cap albedo, the CO2 pressure, and the dust storm frequency. The year-round presence of the CO2 deposits would effectively dry out the atmosphere, while diffusion of water from the regolith would be the only source of water vapor to the atmosphere. We have reviewed the CO2 balance at low obliquity taking into account the asymmetries which make the north and south hemispheres different. Our analysis linked with a numerical model of the polar caps leads us to believe that one summertime cap will always lose its CO2 cover during a Martian year, although we cannot predict which cap this will be. We conclude that significant amounts of water vapor will sublime from the exposed cap during summer, and the Martian atmosphere will support an active water cycle even at low obliquity.

  4. Numerical Modeling of the Last Glacial Maximum Yellowstone Ice Cap Captures Asymmetry in Moraine Ages

    NASA Astrophysics Data System (ADS)

    Anderson, L. S.; Wickert, A. D.; Colgan, W. T.; Anderson, R. S.

    2014-12-01

    thickness of 4 km (McQuarrie and Rogers, 1998)). Furthermore, subsidence in the foredeep formed by the weight of the Yellowstone Ice Cap may be responsible for the deep alluviation (30+ m) of the Yellowstone valley and Jackson Hole, with subsequent ice retreat and glacial isostatic adjustment leading to exhumation and incision of these fill packages.

  5. Assured information flow capping architecture

    NASA Astrophysics Data System (ADS)

    Black, M. D.; Carvin, N. A.

    1985-05-01

    The Tactical Air Control System (TACS) is that set of Tactical Air Force assets used to assess the air and ground situation, and to plan, allocate, commit, and control assigned resources. Previous studies noted that the TACS elements should be more highly distributed to improve survivability in the battlefield of the future. This document reports on the results of the Assured Information Flow Capping Architecture study, which developed governing concepts for communications architectures that can support the information flow requirements of a future, distributed TACS. Architecture comprising existing and planned communications equipment were postulated and compared with a set of goals to identify deficiencies. Architectures using new equipment that resolve many of the deficiencies were then postulated, and areas needing further investigation were identified.

  6. Recent volume and mass changes of Penny Ice Cap (Baffin Island, Nunavut) determined from repeat airborne laser altimetry

    NASA Astrophysics Data System (ADS)

    Schaffer, N.; Zdanowicz, C.; Copland, L.; Burgess, D. O.

    2011-12-01

    Recent observations of accelerated glacier wastage in Greenland and Alaska have prompted reassessments of mass balance trends and volume changes on Canadian Arctic glaciers and ice caps. While long surface mass balance measurements are available from ice caps of the Queen Elizabeth Islands (e.g., Axel Heiberg and Devon islands), no such records exist for Baffin Island glaciers. In the absence of such data, air- and space-borne measurements can be used in combination with ice core data and in-situ ground penetrating radar surveys to evaluate historical and recent trends in ice cover changes. Here, we use repeat laser airborne altimetry surveys conducted in 2000 and 2005 to estimate current volume and mass reduction rates of Penny Ice Cap, the southernmost large ice cap on Baffin Island (~66°N). This work builds on previous surveys for the period 1995-2000 [Abdalati et al. (2004) JGR 109: F04007.] Surface elevation changes along altimetry lines are extrapolated to the entire ice cap using a digital elevation model (DEM). Changes in areal extent of the ice cap are constrained using satellite imagery (e.g. Landsat). From these data and using firn density profiles measured in cores, we estimate the total mass wastage of the ice cap and its contribution to sea level rise.

  7. Seasonal Changes in Mars' North Polar Ice Cap

    NASA Technical Reports Server (NTRS)

    1997-01-01

    , noted previously by HST in 1995 and Mariner 9 in 1972; this may be due to topography, which isn't well known, or to wave structure in the circulation. This map was assembled from WFPC2 images obtained between Dec. 30, 1996 and Jan. 4, 1997.

    March 30, 1997 (early summer): The cap has fully retreated to its remnant core of water-ice. This residual cap is actually almost cut into two by a large, horn-shaped canyon called Chasma Borealis which is cut deeply into the polar terrain. The HST images also reveal a curious layered terrain which is evidence of past climatic changes on Mars. The sublimation of all of the carbon dioxide has exposed the ring of dark sand dunes which encircle the North Polar Cap. Outliers of ice persist south of the polar sand sea (between the 3 o'clock and 9 o'clock positions). The bright circular features at 3, 6, and 9 o'clock are ice-filled craters.

    All images were taken with the Wide Field and Planetary Camera 2. The color is constructed from images taken in red (673 nm) , blue (410 nm) and green (502 nm) light. The resolution at the North Pole ranges from about 115 km/pixel in October '96 to about 45 km/pixel in March '97.

    This image and other images and data received from the Hubble Space Telescope are posted on the World Wide Web on the Space Telescope Science Institute home page at URL http://oposite.stsci.edu/pubinfo/

  8. Seasonal Changes in Mars' North Polar Ice Cap

    NASA Technical Reports Server (NTRS)

    1997-01-01

    , noted previously by HST in 1995 and Mariner 9 in 1972; this may be due to topography, which isn't well known, or to wave structure in the circulation. This map was assembled from WFPC2 images obtained between Dec. 30, 1996 and Jan. 4, 1997.

    March 30, 1997 (early summer): The cap has fully retreated to its remnant core of water-ice. This residual cap is actually almost cut into two by a large, horn-shaped canyon called Chasma Borealis which is cut deeply into the polar terrain. The HST images also reveal a curious layered terrain which is evidence of past climatic changes on Mars. The sublimation of all of the carbon dioxide has exposed the ring of dark sand dunes which encircle the North Polar Cap. Outliers of ice persist south of the polar sand sea (between the 3 o'clock and 9 o'clock positions). The bright circular features at 3, 6, and 9 o'clock are ice-filled craters.

    All images were taken with the Wide Field and Planetary Camera 2. The color is constructed from images taken in red (673 nm) , blue (410 nm) and green (502 nm) light. The resolution at the North Pole ranges from about 115 km/pixel in October '96 to about 45 km/pixel in March '97.

    This image and other images and data received from the Hubble Space Telescope are posted on the World Wide Web on the Space Telescope Science Institute home page at URL http://oposite.stsci.edu/pubinfo/

  9. 31 CFR 50.15 - Cap disclosure.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 31 Money and Finance: Treasury 1 2013-07-01 2013-07-01 false Cap disclosure. 50.15 Section 50.15 Money and Finance: Treasury Office of the Secretary of the Treasury TERRORISM RISK INSURANCE PROGRAM Disclosures as Conditions for Federal Payment § 50.15 Cap disclosure. (a) General. Under section 103(e)(2)...

  10. 31 CFR 50.15 - Cap disclosure.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 31 Money and Finance: Treasury 1 2011-07-01 2011-07-01 false Cap disclosure. 50.15 Section 50.15 Money and Finance: Treasury Office of the Secretary of the Treasury TERRORISM RISK INSURANCE PROGRAM Disclosures as Conditions for Federal Payment § 50.15 Cap disclosure. (a) General. Under section 103(e)(2)...

  11. 31 CFR 50.15 - Cap disclosure.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 31 Money and Finance: Treasury 1 2012-07-01 2012-07-01 false Cap disclosure. 50.15 Section 50.15 Money and Finance: Treasury Office of the Secretary of the Treasury TERRORISM RISK INSURANCE PROGRAM Disclosures as Conditions for Federal Payment § 50.15 Cap disclosure. (a) General. Under section 103(e)(2)...

  12. Sunward convection in both polar caps

    SciTech Connect

    Reiff, P.H.

    1982-08-01

    The geomagnetic storm of July 29, 1977 has been the object of concentrated study. The latter part of the day (1800--2300 UT) is particularly interesting because it is a period of extremely strong, almost directly northward interplanetary magnetic fields (IMF). Such northward IMF's have been related to periods of reversed (i.e., sunward) convection in the polar cap, and this day is no exception. Zanetti et al. (1981), using Triad magnetometer data, show magnetic perturbations implying reversed convection in the northern polar cap, while the Birkeland currents in the southern polar cap are very weak. They give two possible interpretations: (1) merging occurs preferentially in the northern cusp region, and therefore reversed convection is restricted to the northern polar cap or (2) the currents flow predominantly in the sunlit northern polar cap because its conductivity is higher. This paper shows convection data from both the northern polar cap (S3-3) and the southern polar cap (AE-C). In both cases, regions of reversed convection are seen. Therefore the asymmetry of the Birkeland currents is more likely caused by a conductivity asymmetry than a convection asymmetry. It is likely that the low-energy ions seen deep in the polar cap may be traped on closed field lines after merging on both tail lobe boundaries.

  13. 31 CFR 50.15 - Cap disclosure.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 31 Money and Finance: Treasury 1 2010-07-01 2010-07-01 false Cap disclosure. 50.15 Section 50.15 Money and Finance: Treasury Office of the Secretary of the Treasury TERRORISM RISK INSURANCE PROGRAM Disclosures as Conditions for Federal Payment § 50.15 Cap disclosure. (a) General. Under section 103(e)(2)...

  14. Durability of Capped Wood Plastic Composites

    Treesearch

    Mark Mankowski; Mark J. Manning; Damien P. Slowik

    2015-01-01

    Manufacturers of wood plastic composites (WPCs) have recently introduced capped decking to their product lines. These new materials have begun to take market share from the previous generation of uncapped products that possessed a homogenous composition throughout the thickness of their cross-section. These capped offerings have been introduced with claims that the...

  15. 31 CFR 50.15 - Cap disclosure.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 31 Money and Finance: Treasury 1 2014-07-01 2014-07-01 false Cap disclosure. 50.15 Section 50.15 Money and Finance: Treasury Office of the Secretary of the Treasury TERRORISM RISK INSURANCE PROGRAM Disclosures as Conditions for Federal Payment § 50.15 Cap disclosure. (a) General. Under section 103(e)(2)...

  16. 47 CFR 54.507 - Cap.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... Universal Service Support for Schools and Libraries § 54.507 Cap. (a) Amount of the annual cap. In funding... support for schools and libraries shall be automatically increased annually to take into account increases... schools and libraries support mechanism in accordance with the public interest and notwithstanding...

  17. 47 CFR 54.507 - Cap.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... Universal Service Support for Schools and Libraries § 54.507 Cap. (a) Amount of the annual cap. In funding... support for schools and libraries shall be automatically increased annually to take into account increases... schools and libraries support mechanism in accordance with the public interest and notwithstanding...

  18. Ice-core evidence of abrupt climate changes.

    PubMed

    Alley, R B

    2000-02-15

    Ice-core records show that climate changes in the past have been large, rapid, and synchronous over broad areas extending into low latitudes, with less variability over historical times. These ice-core records come from high mountain glaciers and the polar regions, including small ice caps and the large ice sheets of Greenland and Antarctica.

  19. Towards implementation of hollow core fibres for surgical applications

    NASA Astrophysics Data System (ADS)

    Urich, Artur; Delmonte, Tiina; Maier, Robert R. J.; Hand, Duncan P.; Shephard, Jonathan D.

    2011-03-01

    Presently, there is no truly flexible delivery system for light from Er:Yag medical lasers (λ = 2.94 μm) which allows surgeons to work unrestricted. Instead, either a relatively inflexible articulated arm or multi-mode fibre, limited to large bend radii, must be used. One proposed solution is the use of novel types of hollow core - band gap optical fibre rather than more traditional large area solid core fibres. In these silica based fibres, material absorption and damage limitations are overcome by using a photonic band gap structure. This confines radiation to lower order modes, that are guided in a small diameter air core. The overall fibre diameter is also smaller, which allows a smaller mechanical bend radius. Together with the guidance in air, this improves the laser power damage threshold. However, there are many practical hurdles that must be overcome to achieve a robust system for use in surgery. One of the main problems is that the fibre structure is hollow and ingress of dust, vapour, fluids and other contaminants need to be prevented to ensure safe in-vivo usage. Additionally, any infibre contamination will degrade the laser damage resistance of the fibre leading to potential catastrophic failure. The development of a robust and hermetically sealed end cap for the fibre, without adversely affecting beam quality or damage threshold is an essential prerequisite for the safe and efficient use of such fibres in surgery. In this paper we report on the progress on implementing end caps and describe novel methods of sealing off these hollow fibres in particular for surgical applications. This work will demonstrate that the use of these superior fibres with low loss guidance at 2.94 μm in surgery is feasible.

  20. Lead in candle emissions.

    PubMed

    Wasson, Shirley J; Guo, Zhishi; McBrian, Jenia A; Beach, Laura O

    2002-09-16

    The candle-using public should be made aware that the core of candle wicks may contain lead. Used as a stiffening agent to keep the wick out of the molten wax, lead can be emitted as particulates to the air and then deposited on indoor surfaces. To define the problem, 100 sets of candles (two or more identical candles) were purchased locally. The criterion for purchase was that the candles must appear to contain a metal-cored wick or be covered by a metallic pigment. Of the candles purchased, 8% contained lead wicks. The wicks were 39-74% lead (the remainder was fabric or paper) and the lead cores (approx. 100% lead) had linear densities of 13-27 mg/cm. Candles were burned to completion in a closed chamber to capture the air emissions, and the candle residue was extracted to assess the lead mass balance. It was found that individual candles emitted lead to the air at average rates that ranged from 100 to 1700 microg/h. Assuming realistic indoor conditions, these emission rates were modeled to project room air concentration, child exposure by inhalation, and indoor deposition. Results showed that burning single candles can easily raise the source room concentration above the ambient air lead concentration limit of 1.5 microg/m3 set by EPA. Burning multiple candles can elevate it above OSHA permissible exposure limits of 50 microg/m3. Although blood lead levels have dropped precipitously in the United States since lead was phased out of gasoline in 1986, nearly 900,000 children still had levels above 10 microg/dl during NHANES III. Considering that candle sales in the US are estimated at $1-2 billion per year, and that children may spend as much as 88% of their time indoors, it is reasonable to suspect that some blood lead elevation in children arises from indoor micro-environments where lead-wick candles are burned.

  1. "Move the cap" technique for ambiguous or impenetrable proximal cap of coronary total occlusion.

    PubMed

    Vo, Minh N; Karmpaliotis, Dimitri; Brilakis, Emmanouil S

    2016-03-01

    Antegrade crossing remains the most commonly employed crossing strategy for coronary chronic total occlusions (CTOs) but can be challenging to perform in cases of ambiguous or impenetrable proximal cap. To successfully treat such cases, we describe a technique named "move the cap," in which the subintimal space is entered proximal to the proximal cap using a stiff coronary guidewire or facilitated by inflating a slightly oversized balloon. Subintimal guidewire entry is followed by standard antegrade dissection and re-entry. The "move the cap" technique can facilitate crossing of CTOs with ambiguous or impenetrable cap, while minimizing the risk of perforation. This technique is also useful for treating balloon uncrossable lesions.

  2. Lead Toxicity

    MedlinePlus

    Agency for Toxic Substances and Disease Registry Case Studies in Environmental Medicine (CSEM) Patient Information Sheet Lead Toxicity What is lead? How are people exposed to lead? • Lead is a soft, blue- ...

  3. Lead Poisoning

    MedlinePlus

    ... high levels of lead in household dust. DRINKING WATER: Lead may get into drinking water when materials used in plumbing materials, such as ... and dishware. Lead may also be in contaminated water. Lead poisoning is harmful to human health and ...

  4. Origin of interfacial perpendicular magnetic anisotropy in MgO/CoFe/metallic capping layer structures

    PubMed Central

    Peng, Shouzhong; Wang, Mengxing; Yang, Hongxin; Zeng, Lang; Nan, Jiang; Zhou, Jiaqi; Zhang, Youguang; Hallal, Ali; Chshiev, Mairbek; Wang, Kang L.; Zhang, Qianfan; Zhao, Weisheng

    2015-01-01

    Spin-transfer-torque magnetic random access memory (STT-MRAM) attracts extensive attentions due to its non-volatility, high density and low power consumption. The core device in STT-MRAM is CoFeB/MgO-based magnetic tunnel junction (MTJ), which possesses a high tunnel magnetoresistance ratio as well as a large value of perpendicular magnetic anisotropy (PMA). It has been experimentally proven that a capping layer coating on CoFeB layer is essential to obtain a strong PMA. However, the physical mechanism of such effect remains unclear. In this paper, we investigate the origin of the PMA in MgO/CoFe/metallic capping layer structures by using a first-principles computation scheme. The trend of PMA variation with different capping materials agrees well with experimental results. We find that interfacial PMA in the three-layer structures comes from both the MgO/CoFe and CoFe/capping layer interfaces, which can be analyzed separately. Furthermore, the PMAs in the CoFe/capping layer interfaces are analyzed through resolving the magnetic anisotropy energy by layer and orbital. The variation of PMA with different capping materials is attributed to the different hybridizations of both d and p orbitals via spin-orbit coupling. This work can significantly benefit the research and development of nanoscale STT-MRAM. PMID:26656721

  5. Ground penetrating radar and direct current resistivity evaluation of the desiccation test cap, Savannah River Site

    SciTech Connect

    Wyatt, D.E.; Cumbest, R.J.

    1996-04-01

    The Savannah River Site (SRS) has a variety of waste units that may be temporarily or permanently stabilized by closure using an impermeable cover to prevent groundwater infiltration. The placement of an engineered kaolin clay layer over a waste unit is an accepted and economical technique for providing an impermeable cover but the long term stability and integrity of the clay in non-arid conditions is unknown. A simulated kaolin cap has been constructed at the SRA adjacent to the Burial Ground Complex. The cap is designed to evaluate the effects of desiccation on clay integrity, therefore half of the cap is covered with native soil to prevent drying, while the remainder of the cap is exposed. Measurements of the continuing impermeability of a clay cap are difficult because intrusive techniques may locally compromise the structure. Point measurements made to evaluate clay integrity, such as those from grid sampling or coring and made through a soil cover, may miss cracks, joints or fissures, and may not allow for mapping of the lateral extent of elongate features. Because of these problems, a non-invasive technique is needed to map clay integrity, below a soil or vegetation cover, which is capable of moderate to rapid investigation speeds. Two non-intrusive geophysical techniques, direct current resistivity and ground penetrating radar (GPR), have been successful at the SRS in geologically mapping shallow subsurface clay layers. The applicability of each technique in detecting the clay layer in the desiccation test cap and associated anomalies was investigated.

  6. Origin of interfacial perpendicular magnetic anisotropy in MgO/CoFe/metallic capping layer structures.

    PubMed

    Peng, Shouzhong; Wang, Mengxing; Yang, Hongxin; Zeng, Lang; Nan, Jiang; Zhou, Jiaqi; Zhang, Youguang; Hallal, Ali; Chshiev, Mairbek; Wang, Kang L; Zhang, Qianfan; Zhao, Weisheng

    2015-12-11

    Spin-transfer-torque magnetic random access memory (STT-MRAM) attracts extensive attentions due to its non-volatility, high density and low power consumption. The core device in STT-MRAM is CoFeB/MgO-based magnetic tunnel junction (MTJ), which possesses a high tunnel magnetoresistance ratio as well as a large value of perpendicular magnetic anisotropy (PMA). It has been experimentally proven that a capping layer coating on CoFeB layer is essential to obtain a strong PMA. However, the physical mechanism of such effect remains unclear. In this paper, we investigate the origin of the PMA in MgO/CoFe/metallic capping layer structures by using a first-principles computation scheme. The trend of PMA variation with different capping materials agrees well with experimental results. We find that interfacial PMA in the three-layer structures comes from both the MgO/CoFe and CoFe/capping layer interfaces, which can be analyzed separately. Furthermore, the PMAs in the CoFe/capping layer interfaces are analyzed through resolving the magnetic anisotropy energy by layer and orbital. The variation of PMA with different capping materials is attributed to the different hybridizations of both d and p orbitals via spin-orbit coupling. This work can significantly benefit the research and development of nanoscale STT-MRAM.

  7. Applications of Phosphate Modification and Labeling to Study (m)RNA Caps.

    PubMed

    Warminski, Marcin; Sikorski, Pawel J; Kowalska, Joanna; Jemielity, Jacek

    2017-02-01

    The cap is a natural modification present at the 5' ends of eukaryotic messenger RNA (mRNA), which because of its unique structural features, mediates essential biological functions during the process of gene expression. The core structural feature of the mRNA cap is an N7-methylguanosine moiety linked by a 5'-5' triphosphate chain to the first transcribed nucleotide. Interestingly, other RNA 5' end modifications structurally and functionally resembling the m(7)G cap have been discovered in different RNA types and in different organisms. All these structures contain the 'inverted' 5'-5' oligophosphate bridge, which is necessary for interaction with specific proteins and also serves as a cleavage site for phosphohydrolases regulating RNA turnover. Therefore, cap analogs containing oligophosphate chain modifications or carrying spectroscopic labels attached to phosphate moieties serve as attractive molecular tools for studies on RNA metabolism and modification of natural RNA properties. Here, we review chemical, enzymatic, and chemoenzymatic approaches that enable preparation of modified cap structures and RNAs carrying such structures, with emphasis on phosphate-modified mRNA cap analogs and their potential applications.

  8. The Ca(2+)-dependent activator protein for secretion CAPS: do I dock or do I prime?

    PubMed

    Stevens, David R; Rettig, Jens

    2009-02-01

    The "Ca(2+)-dependent activator protein for secretion" (CAPS) is a protein which reconstitutes regulated secretion in permeabilized neuroendocrine cells. It is generally accepted that CAPS plays an important role in the release of the contents of dense core vesicles in the nervous system as well as in a variety of other secretory tissues. At which step in the exocytotic process CAPS functions as well as its role in the fusion of synaptic vesicles is still under dispute. A recent growth spurt in the CAPS field has been fueled by genetic approaches in Caenorhabditis elegans and Drosophila as well as the application of knockout and knockdown approaches in mouse cells and in cell lines, respectively. We have attempted to review the body of work that established CAPS as an important regulator of secretion and to describe new information that has furthered our understanding of how CAPS may function. We discuss the conclusions, point out areas where controversy remains, and suggest directions for future experiments.

  9. Origin of interfacial perpendicular magnetic anisotropy in MgO/CoFe/metallic capping layer structures

    NASA Astrophysics Data System (ADS)

    Peng, Shouzhong; Wang, Mengxing; Yang, Hongxin; Zeng, Lang; Nan, Jiang; Zhou, Jiaqi; Zhang, Youguang; Hallal, Ali; Chshiev, Mairbek; Wang, Kang L.; Zhang, Qianfan; Zhao, Weisheng

    2015-12-01

    Spin-transfer-torque magnetic random access memory (STT-MRAM) attracts extensive attentions due to its non-volatility, high density and low power consumption. The core device in STT-MRAM is CoFeB/MgO-based magnetic tunnel junction (MTJ), which possesses a high tunnel magnetoresistance ratio as well as a large value of perpendicular magnetic anisotropy (PMA). It has been experimentally proven that a capping layer coating on CoFeB layer is essential to obtain a strong PMA. However, the physical mechanism of such effect remains unclear. In this paper, we investigate the origin of the PMA in MgO/CoFe/metallic capping layer structures by using a first-principles computation scheme. The trend of PMA variation with different capping materials agrees well with experimental results. We find that interfacial PMA in the three-layer structures comes from both the MgO/CoFe and CoFe/capping layer interfaces, which can be analyzed separately. Furthermore, the PMAs in the CoFe/capping layer interfaces are analyzed through resolving the magnetic anisotropy energy by layer and orbital. The variation of PMA with different capping materials is attributed to the different hybridizations of both d and p orbitals via spin-orbit coupling. This work can significantly benefit the research and development of nanoscale STT-MRAM.

  10. Regulation of Phytochrome Message Abundance in Root Caps of Maize 1

    PubMed Central

    Johnson, Ellen M.; Pao, Lily I.; Feldman, Lewis J.

    1991-01-01

    In many cultivars of maize (Zea mays L.) red light affects root development via the photomorphogenetic pigment phytochrome. The site of perception for the light is the root cap. In the maize cultivar Merit, we investigated phytochrome-mediated events in the cap. We established that the message encoded by the phyA1 gene was most abundant in dark-grown tissue and was asymmetrically distributed in the root cap, with greatest expression in the cells which make up the central columella core of the cap. Phytochrome message was negatively autoregulated in a specific region within the root cap. This autoregulation was sensitive to very-low-fluence red light, and thus was characterized as a phytochrome-mediated, very-low-fluence event. The kinetics of message reaccumulation in the dark were also examined and compared to the kinetics of the light requirement for root gravitropism in this cultivar. Similarly, the degree of autoregulation present in two other maize cultivars with different light requirements for gravitropic sensitivity was investigated. It appears that the Merit cultivar expresses a condition of hypersensitivity to phytochromemediated light regulation in root tissues. We conclude that phytochrome regulates many activities within the cap, but the degree to which these activities share common phytochrome-mediated steps in not known. Images Figure 1 Figure 2 Figure 6 PMID:11537488

  11. The small ice cap instability in diffusive climate models

    NASA Technical Reports Server (NTRS)

    North, G. R.

    1984-01-01

    Simple climate models which invoke diffusive heat transport and ice cap albedo feedback have equilibrium solutions with no stable ice cap smaller than a radius of about 20 deg on a great circle. Attention is presently given to a solution of this phenomenon which is physically appealing. The ice-free solution has a thermal minimum, and if the minimum temperature is just above the critical value for ice formation, then the artificial addition of a patch of ice leads to a widespread depression of the temperature below the critical freezing temperature. A second stable solution will then exist whose spatial extent is determined by the range of the influence function of a point sink of heat, due to the albedo shift in the patch.

  12. Capping of rare earth silicide nanowires on Si(001)

    SciTech Connect

    Appelfeller, Stephan; Franz, Martin; Kubicki, Milan; Dähne, Mario; Reiß, Paul; Niermann, Tore; Lehmann, Michael; Schubert, Markus Andreas

    2016-01-04

    The capping of Tb and Dy silicide nanowires grown on Si(001) was studied using scanning tunneling microscopy and cross-sectional high-resolution transmission electron microscopy. Several nanometers thick amorphous Si films deposited at room temperature allow an even capping, while the nanowires maintain their original structural properties. Subsequent recrystallization by thermal annealing leads to more compact nanowire structures and to troughs in the Si layer above the nanowires, which may even reach down to the nanowires in the case of thin Si films, as well as to V-shaped stacking faults forming along (111) lattice planes. This behavior is related to strain due to the lattice mismatch between the Si overlayer and the nanowires.

  13. On the microphysical state of the Martian seasonal caps

    NASA Technical Reports Server (NTRS)

    Eluszkiewicz, Janusz

    1993-01-01

    An analysis of the microphysical processes involved in pressureless sintering leads to the view that CO2 in the Martian seasonal polar caps can metamorphose into an annealed polycrystalline layer, if freshly condensed grains are smaller than 10 microns. Such large-area/low-porosity CO2 deposits may be associated with the mm-to-cm-scaled path lengths entailed by the explanation of several weak absorption features in the 1.5- and 2.3-micron spectral regions. Such an annealed layer would become transparent enough during the later stages of spring sublimation to establish a basis for the dichotomy between the north and south caps' albedos in the underlying substrate.

  14. The small ice cap instability in diffusive climate models

    NASA Technical Reports Server (NTRS)

    North, G. R.

    1984-01-01

    Simple climate models which invoke diffusive heat transport and ice cap albedo feedback have equilibrium solutions with no stable ice cap smaller than a radius of about 20 deg on a great circle. Attention is presently given to a solution of this phenomenon which is physically appealing. The ice-free solution has a thermal minimum, and if the minimum temperature is just above the critical value for ice formation, then the artificial addition of a patch of ice leads to a widespread depression of the temperature below the critical freezing temperature. A second stable solution will then exist whose spatial extent is determined by the range of the influence function of a point sink of heat, due to the albedo shift in the patch.

  15. The role of rotation and polar-cap currents on pulsar radio emission and polarization

    SciTech Connect

    Kumar, D.; Gangadhara, R. T. E-mail: ganga@iiap.res.in

    2013-06-01

    Perturbations such as rotation and polar-cap current (PC-current) have been believed to greatly affect the pulsar radio emission and polarization. The two effects have not been considered simultaneously in the literature; each one of these has been considered separately, and a picture has been deduced by simply superposing them, but such an approach can lead to spurious results. Hence, by considering pulsar rotation and PC-current perturbations together instead of one at a time, we have developed a single particle curvature radiation model, which is expected to be much more realistic. By simulating a set of typical pulse profiles, we have made an attempt to explain most of the observational results of pulsar radio emission and polarization. The model predicts that due to the perturbations the leading side component can become either stronger or weaker than the corresponding trailing one in any given cone, depending on the passage of the sight line and modulation (nonuniform source distribution). Further, we find that the phase delay of the polarization angle inflection point with respect to the core component greatly depends on the viewing geometry. The correlation between the sign reversal of circular polarization and the polarization angle swing in the case of core-dominated pulsars becomes obscure once the perturbations and modulation become significant. However, the correlation between the negative circular polarization and the increasing polarization angle and vice versa is very clear in the case of conal-double pulsars. The 'kinky'-type distortions in polarization angle swing could be due to the incoherent superposition of modulated emission in the presence of strong perturbations.

  16. A novel route for preparing 5' cap mimics and capped RNAs: phosphate-modified cap analogues obtained via click chemistry.

    PubMed

    Walczak, Sylwia; Nowicka, Anna; Kubacka, Dorota; Fac, Kaja; Wanat, Przemyslaw; Mroczek, Seweryn; Kowalska, Joanna; Jemielity, Jacek

    2017-01-01

    The significant biological role of the mRNA 5' cap in translation initiation makes it an interesting subject for chemical modifications aimed at producing useful tools for the selective modulation of intercellular processes and development of novel therapeutic interventions. However, traditional approaches to the chemical synthesis of cap analogues are time-consuming and labour-intensive, which impedes the development of novel compounds and their applications. Here, we explore a different approach for synthesizing 5' cap mimics, making use of click chemistry (CuAAC) to combine two mononucleotide units and yield a novel class of dinucleotide cap analogues containing a triazole ring within the oligophosphate chain. As a result, we synthesized a library of 36 mRNA cap analogues differing in the location of the triazole ring, the polyphosphate chain length, and the type of linkers joining the phosphate and the triazole moieties. After biochemical evaluation, we identified two analogues that, when incorporated into mRNA, produced transcripts translated with efficiency similar to compounds unmodified in the oligophosphate bridge obtained by traditional synthesis. Moreover, we demonstrated that the triazole-modified cap structures can be generated at the RNA 5' end using two alternative capping strategies: either the typical co-transcriptional approach, or a new post-transcriptional approach based on CuAAC. Our findings open new possibilities for developing chemically modified mRNAs for research and therapeutic applications, including RNA-based vaccinations.

  17. Mars Seasonal Polar Caps as a Test of the Equivalence Principle

    NASA Technical Reports Server (NTRS)

    Rubincam, Daivd Parry

    2011-01-01

    The seasonal polar caps of Mars can be used to test the equivalence principle in general relativity. The north and south caps, which are composed of carbon dioxide, wax and wane with the seasons. If the ratio of the inertial to gravitational masses of the caps differs from the same ratio for the rest of Mars, then the equivalence principle fails, Newton's third law fails, and the caps will pull Mars one way and then the other with a force aligned with the planet's spin axis. This leads to a secular change in Mars's along-track position in its orbit about the Sun, and to a secular change in the orbit's semimajor axis. The caps are a poor E6tv6s test of the equivalence principle, being 4 orders-of-magnitude weaker than laboratory tests and 7 orders-of-magnitude weaker than that found by lunar laser ranging; the reason is the small mass of the caps compared to Mars as a whole. The principal virtue of using Mars is that the caps contain carbon, an element not normally considered in such experiments. The Earth with its seasonal snow cover can also be used for a similar test.

  18. Effect of tissue properties, shape and orientation of microcalcifications on vulnerable cap stability using different hyperelastic constitutive models

    PubMed Central

    Cardoso, Luis; Kelly-Arnold, Adreanne; Maldonado, Natalia; Laudier, Damien; Weinbaum, Sheldon

    2014-01-01

    Approximately half of all cardiovascular deaths associated with acute coronary syndrome occur when the thin fibrous cap tissue overlying the necrotic core in a coronary vessel is torn, ripped or fissured under the action of high blood pressure. From a biomechanics point of view, the rupture of an atheroma is due to increased mechanical stresses in the lesion, in which the ultimate stress (i.e. peak circumferential stress (PCS) at failure) of the tissue is exceeded. Several factors including the cap thickness, morphology, residual stresses and tissue composition of the atheroma have been shown to affect the PCS. Also important, we recently demonstrated that microcalcifications (µCalcs) > 5 µm are a common feature in human atheroma caps, which behave as local stress concentrators, increasing the local tissue stress by at least a factor of two surpassing the ultimate stress threshold for cap tissue rupture. In the present study, we used both idealized µCalcs with spherical shape and actual µCalcs from human coronary atherosclerotic caps, to determine their effect on increasing the circumferential stress in the fibroatheroma cap using different hyperelastic constitutive models. We have found that the stress concentration factor (SCF) produced by µCalcs in the fibroatheroma cap is affected by the material tissue properties, µCalcs spacing, aspect ratio and their alignment relative to the tensile axis of the cap. PMID:24503048

  19. Effect of tissue properties, shape and orientation of microcalcifications on vulnerable cap stability using different hyperelastic constitutive models.

    PubMed

    Cardoso, Luis; Kelly-Arnold, Adreanne; Maldonado, Natalia; Laudier, Damien; Weinbaum, Sheldon

    2014-03-03

    Approximately half of all cardiovascular deaths associated with acute coronary syndrome occur when the thin fibrous cap tissue overlying the necrotic core in a coronary vessel is torn, ripped or fissured under the action of high blood pressure. From a biomechanics point of view, the rupture of an atheroma is due to increased mechanical stresses in the lesion, in which the ultimate stress (i.e. peak circumferential stress (PCS) at failure) of the tissue is exceeded. Several factors including the cap thickness, morphology, residual stresses and tissue composition of the atheroma have been shown to affect the PCS. Also important, we recently demonstrated that microcalcifications (μCalcs>5 µm are a common feature in human atheroma caps, which behave as local stress concentrators, increasing the local tissue stress by at least a factor of two surpassing the ultimate stress threshold for cap tissue rupture. In the present study, we used both idealized µCalcs with spherical shape and actual µCalcs from human coronary atherosclerotic caps, to determine their effect on increasing the circumferential stress in the fibroatheroma cap using different hyperelastic constitutive models. We have found that the stress concentration factor (SCF) produced by μCalcs in the fibroatheroma cap is affected by the material tissue properties, μCalcs spacing, aspect ratio and their alignment relative to the tensile axis of the cap.

  20. Innovation under cap-and-trade programs

    PubMed Central

    Taylor, Margaret R.

    2012-01-01

    Policies incentivizing the private sector to reach its innovative potential in “clean” technologies are likely to play a key role in achieving climate stabilization. This article explores the relationship between innovation and cap-and-trade programs (CTPs)—the world's most prominent climate policy instrument—through empirical evidence drawn from successful CTPs for sulfur dioxide and nitrogen oxide control. The article shows that before trading began for these CTPs, analysts overestimated the value of allowances in a pattern suggestive of the frequent a priori overestimation of the compliance costs of regulation. When lower-than-expected allowance prices were observed, in part because of the unexpected range of abatement approaches used in the lead-up to trading, emissions sources chose to bank allowances in significant numbers and reassess abatement approaches going forward. In addition, commercially oriented inventive activity declined for emissions-reducing technologies with a wide range of costs and technical characteristics, dropping from peaks before the establishment of CTPs to nadirs a few years into trading. This finding is consistent with innovators deciding during trading that their research and development investments should be reduced, based on assessments of future market conditions under the relevant CTPs. The article concludes with a discussion of the results and their implications for innovation and climate policy. PMID:22411797

  1. Innovation under cap-and-trade programs.

    PubMed

    Taylor, Margaret R

    2012-03-27

    Policies incentivizing the private sector to reach its innovative potential in "clean" technologies are likely to play a key role in achieving climate stabilization. This article explores the relationship between innovation and cap-and-trade programs (CTPs)--the world's most prominent climate policy instrument--through empirical evidence drawn from successful CTPs for sulfur dioxide and nitrogen oxide control. The article shows that before trading began for these CTPs, analysts overestimated the value of allowances in a pattern suggestive of the frequent a priori overestimation of the compliance costs of regulation. When lower-than-expected allowance prices were observed, in part because of the unexpected range of abatement approaches used in the lead-up to trading, emissions sources chose to bank allowances in significant numbers and reassess abatement approaches going forward. In addition, commercially oriented inventive activity declined for emissions-reducing technologies with a wide range of costs and technical characteristics, dropping from peaks before the establishment of CTPs to nadirs a few years into trading. This finding is consistent with innovators deciding during trading that their research and development investments should be reduced, based on assessments of future market conditions under the relevant CTPs. The article concludes with a discussion of the results and their implications for innovation and climate policy.

  2. Evidence for episodic basin dewatering in salt-dome cap rocks

    SciTech Connect

    Hallager, W.S. ); Ulrich, M.R. ); Kyle, J.R.; Gose, W.A. ); Price, P.E. )

    1990-08-01

    A detailed record of episodic basin-dewatering events is preserved in the anhydrite cap rocks to two Gulf Coast salt domes. Metal rich brines were intermittently expelled geopressured zones deep in the stratigraphic section and were channeled upward along escape structures bounding the salt diapirs. Overhanging anhydrite cap rock helped to focus some escaping fluid into the zone of dissolution between the top of salt and overlying residual anhydrite cap rock. Iron, lead, and zinc sulfide solubilities were exceeded in this zone, possibly in response to dissolution and reduction of cap-rock sulfates. Because the metalliferous brines entered the dissolution zone intermittently, they were recorded as relatively thin horizontal bands of sulfide sandwiched between thicker accumulations of anhydrite. Continued dissolution of salt and underplating of residual anhydrite caused the sulfide bands to be displaced upward relative to the base of the cap, leading to an inverted stratigraphic record of basin-dewatering events. Paleomagnetic data from the Winnfield salt dome suggest the sulfide-producing basin-dewatering events and anhydrite cap-rock accumulation occurred between 157 and 145 Ma.

  3. CAPS and INMS Major Accomplishments

    NASA Astrophysics Data System (ADS)

    Waite, J. Hunter

    2014-05-01

    The Cassini-Huygens Ion Neutral Mass Spectrometer (Cassini INMS) and the Cassini Plasma Spectrometer (CAPS) have provided "discovery" science at Titan, Enceladus, Rhea/Dione, and throughout the magnetosphere of Saturn during the course of the mission. In this talk we will review some of the major scientific achievements: 1) the discovery of an extremely complex ion neutral organic chemistry in Titan's upper atmosphere that forms the building blocks for aerosol processes below, 2) the discovery of gases and grains emanating from Enceladus' cryo-geysers that tell us about chemical processes in an interior sea, 3) the first direct compositional measurements of sputtered icy moon surfaces, 4) the clearest example to date of the complex plasma interchange processes that occur in rapidly rotating magnetospheres of gas giants, initiating global dynamic processes that enable Saturn to shed the plasma from Enceladus' plume, and complete with a myriad of longitudinal and solar local-time variations, and 5) the dominance of Enceladus water outgassing as a source of magnetospheric plasma that stretches out to Titan and provides oxygen that can convert Titan's rich nitrile populations into amino acids.

  4. Identification of a cyclase-associated protein (CAP) homologue in Dictyostelium discoideum and characterization of its interaction with actin.

    PubMed

    Gottwald, U; Brokamp, R; Karakesisoglou, I; Schleicher, M; Noegel, A A

    1996-02-01

    In search for novel actin binding proteins in Dictyostelium discoideum we have isolated a cDNA clone coding for a protein of approximately 50 kDa that is highly homologous to the class of adenylyl cyclase-associated proteins (CAP). In Saccharomyces cerevisiae the amino-terminal part of CAP is involved in the regulation of the adenylyl cyclase whereas the loss of the carboxyl-terminal domain results in morphological and nutritional defects. To study the interaction of Dictyostelium CAP with actin, the complete protein and its amino-terminal and carboxyl-terminal domains were expressed in Escherichia coli and used in actin binding assays. CAP sequestered actin in a Ca2+ independent way. This activity was localized to the carboxyl-terminal domain. CAP and its carboxyl-terminal domain led to a fluorescence enhancement of pyrene-labeled G-actin up to 50% indicating a direct interaction, whereas the amino-terminal domain did not enhance. In polymerization as well as in viscometric assays the ability of the carboxyl-terminal domain to sequester actin and to prevent F-actin formation was approximately two times higher than that of intact CAP. The sequestering activity of full length CAP could be inhibited by phosphatidylinositol 4,5-bisphosphate (PIP2), whereas the activity of the carboxyl-terminal domain alone was not influenced, suggesting that the amino-terminal half of the protein is required for the PIP2 modulation of the CAP function. In profilin-minus cells the CAP concentration is increased by approximately 73%, indicating that CAP may compensate some profilin functions in vivo. In migrating D. discoideum cells CAP was enriched at anterior and posterior plasma membrane regions. Only a weak staining of the cytoplasm was observed. In chemotactically stimulated cells the protein was very prominent in leading fronts. The data suggest an involvement of D. discoideum CAP in microfilament reorganization near the plasma membrane in a PIP2-regulated manner.

  5. Carotid Plaque Morphological Classification Compared With Biomechanical Cap Stress: Implications for a Magnetic Resonance Imaging-Based Assessment.

    PubMed

    Gijsen, Frank J H; Nieuwstadt, Harm A; Wentzel, Jolanda J; Verhagen, Hence J M; van der Lugt, Aad; van der Steen, Antonius F W

    2015-08-01

    Two approaches to target plaque vulnerability-a histopathologic classification scheme and a biomechanical analysis-were compared and the implications for noninvasive risk stratification of carotid plaques using magnetic resonance imaging were assessed. Seventy-five histological plaque cross sections were obtained from carotid endarterectomy specimens from 34 patients (>70% stenosis) and subjected to both a Virmani histopathologic classification (thin fibrous cap atheroma with <0.2-mm cap thickness, presumed vulnerable) and a peak cap stress computation (<140 kPa: presumed stable; >300 kPa: presumed vulnerable). To demonstrate the implications for noninvasive plaque assessment, numeric simulations of a typical carotid magnetic resonance imaging protocol were performed (0.62×0.62 mm(2) in-plane acquired voxel size) and used to obtain the magnetic resonance imaging-based peak cap stress. Peak cap stress was generally associated with histological classification. However, only 16 of 25 plaque cross sections could be labeled as high-risk (peak cap stress>300 kPa and classified as a thin fibrous cap atheroma). Twenty-eight of 50 plaque cross sections could be labeled as low-risk (a peak cap stress<140 kPa and not a thin fibrous cap atheroma), leading to a κ=0.39. 31 plaques (41%) had a disagreement between both classifications. Because of the limited magnetic resonance imaging voxel size with regard to cap thickness, a noninvasive identification of only a group of low-risk, thick-cap plaques was reliable. Instead of trying to target only vulnerable plaques, a more reliable noninvasive identification of a select group of stable plaques with a thick cap and low stress might be a more fruitful approach to start reducing surgical interventions on carotid plaques. © 2015 American Heart Association, Inc.

  6. Why is the north polar cap on Mars different than the south polar cap?

    NASA Technical Reports Server (NTRS)

    Lindner, Bernhard Lee

    1994-01-01

    One of the most puzzling mysteries about the planet Mars is the hemispherical asymmetry in the polar caps. Every spring the seasonal polar cap of CO2 recedes until the end of summer, when only a small part, the residual polar cap, remains. During the year that Viking observed Mars, the residual polar cap was composed of water ice in the northern hemisphere but was primarily carbon dioxide ice in the southern hemisphere. Scientists have sought to explain this asymmetry by modeling observations of the latitudinal recession of the polar cap and seasonal variations in atmospheric pressure (since the seasonal polar caps are primarily frozen atmosphere, they are directly related to changes in atmospheric mass). These models reproduce most aspects of the observed annual variation in atmospheric pressure fairly accurately. Furthermore, the predicted latitudinal recession of the northern polar cap in the spring agrees well with observations, including the fact that the CO2 ice is predicted to completely sublime away. However, these models all predict that the carbon dioxide ice will also sublime away during the summer in the southern hemisphere, unlike what is observed. This paper will show how the radiative effects of ozone, clouds, airborne dust, light penetration into and through the polar cap, and the dependence of albedo on solar zenith angle affect CO2 ice formation and sublimation, and how they help explain the hemispherical asymmetry in the residual polar caps. These effects have not been studied with prior polar cap models.

  7. The pharmaceutical vial capping process: Container closure systems, capping equipment, regulatory framework, and seal quality tests.

    PubMed

    Mathaes, Roman; Mahler, Hanns-Christian; Buettiker, Jean-Pierre; Roehl, Holger; Lam, Philippe; Brown, Helen; Luemkemann, Joerg; Adler, Michael; Huwyler, Joerg; Streubel, Alexander; Mohl, Silke

    2016-02-01

    Parenteral drug products are protected by appropriate primary packaging to protect against environmental factors, including potential microbial contamination during shelf life duration. The most commonly used CCS configuration for parenteral drug products is the glass vial, sealed with a rubber stopper and an aluminum crimp cap. In combination with an adequately designed and controlled aseptic fill/finish processes, a well-designed and characterized capping process is indispensable to ensure product quality and integrity and to minimize rejections during the manufacturing process. In this review, the health authority requirements and expectations related to container closure system quality and container closure integrity are summarized. The pharmaceutical vial, the rubber stopper, and the crimp cap are described. Different capping techniques are critically compared: The most common capping equipment with a rotating capping plate produces the lowest amount of particle. The strength and challenges of methods to control the capping process are discussed. The residual seal force method can characterize the capping process independent of the used capping equipment or CCS. We analyze the root causes of several cosmetic defects associated with the vial capping process.

  8. Determination of lead isotopes in a new Greenland deep ice core at the sub-picogram per gram level by thermal ionization mass spectrometry using an improved decontamination method.

    PubMed

    Han, Changhee; Burn-Nunes, Laurie J; Lee, Khanghyun; Chang, Chaewon; Kang, Jung-Ho; Han, Yeongcheol; Hur, Soon Do; Hong, Sungmin

    2015-08-01

    An improved decontamination method and ultraclean analytical procedures have been developed to minimize Pb contamination of processed glacial ice cores and to achieve reliable determination of Pb isotopes in North Greenland Eemian Ice Drilling (NEEM) deep ice core sections with concentrations at the sub-picogram per gram level. A PL-7 (Fuso Chemical) silica-gel activator has replaced the previously used colloidal silica activator produced by Merck and has been shown to provide sufficiently enhanced ion beam intensity for Pb isotope analysis for a few tens of picograms of Pb. Considering the quantities of Pb contained in the NEEM Greenland ice core and a sample weight of 10 g used for the analysis, the blank contribution from the sample treatment was observed to be negligible. The decontamination and analysis of the artificial ice cores and selected NEEM Greenland ice core sections confirmed the cleanliness and effectiveness of the overall analytical process.

  9. Lead Poisoning

    MedlinePlus

    Lead is a metal that occurs naturally in the earth's crust. Lead can be found in all parts of our ... from human activities such as mining and manufacturing. Lead used to be in paint; older houses may ...

  10. cap alpha. -Methyl-p-tyrosine shifts circadian temperature rhythms

    SciTech Connect

    Cahill, A.L.; Ehret, C.F.

    1982-09-01

    ..cap alpha..-Methyl-p-tyrosine shifts the acrophase (time of highest temperature) of the circadian temperature rhythm of the rat to earlier or later times of day depending on the phase of the cicadian cycle at which the drug is administered. When ..cap alpha..-methyl-p-tyrosine methyl ester HCl is injected intraperitoneally at a dose of 100 mg/kg late in the projected 8-h light phase, the acrophase of the intraperitoneal temperature rhythm is delayed by up to 3 h.However, when the same dose of drug is given 9-10 h into the projected 16-h dark phase of the daily cycle, the acrophase of the temperature rhythm occurs about 2 h earlier than expected. The times of ..cap alpha..-methyl-p-tyrosine administration leading to maximal phase delays or advances are correlated with the times of minimal and maximal turnover of norepinephrine in the hypothalamus. These results suggest that changing rates of norepinephrine turnover in the hypothalamus may regulate the circadian temperature rhythm in rats. The results also emphasize the fact that the effects of drugs may vary as a function of the time of administration. This fact must be taken into account in pharmacologic testing.

  11. A remarkable member of the polyoxometalates: the eight-nickel-capped alpha-keggin polyoxoazonickelate.

    PubMed

    Dong, Lanjun; Huang, Rudan; Wei, Yongge; Chu, Wei

    2009-08-17

    The eight-nickel-capped polyoxoazonickelate, [Ni(20)(OH)(24)(MMT)(12)(SO(4))](NO(3))(2).6H(2)O (1; MMT = 2-mercapto-5-methyl-1,3,4-thiadiazole), has been synthesized, which has an alpha-Keggin structure with eight nickel caps. In this structure, the polyatom is the late transition metal Ni(II); the central heteroatom is S, and the organic terminal ligand becomes the primary part of the Keggin structure. This is a Keplerate-type cluster, which shows a central Ni(II)(12) cuboctahedron formed by the 12 Ni(II) centers of the classical alpha-Keggin core and a Ni(II)(8) hexahedron formed by the eight nickel caps.

  12. An inorganic capping strategy for the seeded growth of versatile bimetallic nanostructures

    DOE PAGES

    Pei, Yuchen; Maligal-Ganesh, Raghu V.; Xiao, Chaoxian; ...

    2015-09-11

    Metal nanostructures have attracted great attention in various fields due to their tunable properties through precisely tailored sizes, compositions and structures. Using mesoporous silica (mSiO2) as the inorganic capping agent and encapsulated Pt nanoparticles as the seeds, we developed a robust seeded growth method to prepare uniform bimetallic nanoparticles encapsulated in mesoporous silica shells (PtM@mSiO2, M = Pd, Rh, Ni and Cu). Unexpectedly, we found that the inorganic silica shell is able to accommodate an eight-fold volume increase in the metallic core by reducing its thickness. The bimetallic nanoparticles encapsulated in mesoporous silica shells showed enhanced catalytic properties and thermalmore » stabilities compared with those prepared with organic capping agents. As a result, this inorganic capping strategy could find a broad application in the synthesis of versatile bimetallic nanostructures with exceptional structural control and enhanced catalytic properties.« less

  13. An inorganic capping strategy for the seeded growth of versatile bimetallic nanostructures

    SciTech Connect

    Pei, Yuchen; Maligal-Ganesh, Raghu V.; Xiao, Chaoxian; Goh, Tian -Wei; Brashler, Kyle; Gustafson, Jeffrey A.; Huang, Wenyu

    2015-09-11

    Metal nanostructures have attracted great attention in various fields due to their tunable properties through precisely tailored sizes, compositions and structures. Using mesoporous silica (mSiO2) as the inorganic capping agent and encapsulated Pt nanoparticles as the seeds, we developed a robust seeded growth method to prepare uniform bimetallic nanoparticles encapsulated in mesoporous silica shells (PtM@mSiO2, M = Pd, Rh, Ni and Cu). Unexpectedly, we found that the inorganic silica shell is able to accommodate an eight-fold volume increase in the metallic core by reducing its thickness. The bimetallic nanoparticles encapsulated in mesoporous silica shells showed enhanced catalytic properties and thermal stabilities compared with those prepared with organic capping agents. As a result, this inorganic capping strategy could find a broad application in the synthesis of versatile bimetallic nanostructures with exceptional structural control and enhanced catalytic properties.

  14. Tip cap for a turbine rotor blade

    DOEpatents

    Kimmel, Keith D

    2014-03-25

    A turbine rotor blade with a spar and shell construction, and a tip cap that includes a row of lugs extending from a bottom side that form dovetail grooves that engage with similar shaped lugs and grooves on a tip end of the spar to secure the tip cap to the spar against radial displacement. The lug on the trailing edge end of the tip cap is aligned perpendicular to a chordwise line of the blade in the trailing edge region in order to minimize stress due to the lugs wanting to bend under high centrifugal loads. A two piece tip cap with lugs at different angles will reduce the bending stress even more.

  15. At the Edge of a Polar Cap

    NASA Image and Video Library

    2014-05-22

    The deep chasm that formed on the polar cap edge is identified as an area of strong down-slope winds and has a clear connection to Mars largest dune field, Olympia Undae as observed by NASA Mars Reconnaissance Orbiter.

  16. CCiCap: Sierra Nevada Corporation

    NASA Image and Video Library

    NASA announced today its plans to partner with Sierra Nevada Corp. (SNC) for the next phase of the agency's Commercial Crew Program (CCP). Called Commercial Crew integrated Capability (CCiCap), the...

  17. Perfluorocarbon vapor tagging of blasting cap detonators

    DOEpatents

    Dietz, R.N.; Senum, G.I.

    A plug for a blasting cap is made of an elastomer in which is dissolved a perfluorocarbon. The perfluorocarbon is released as a vapor into the ambient over a long period of time to serve as a detectable taggant.

  18. Regulation of Flavivirus RNA Synthesis and Capping

    PubMed Central

    Saeedi, Bejan J.; Geiss, Brian J.

    2013-01-01

    RNA viruses, such as flaviviruses, are able to efficiently replicate and cap their RNA genomes in vertebrate and invertebrate cells. Flaviviruses use several specialized proteins to first make an uncapped negative strand copy of the viral genome that is used as a template for the synthesis of large numbers of capped genomic RNAs. Despite using relatively simple mechanisms to replicate their RNA genomes, there are significant gaps in our understanding of how flaviviruses switch between negative and positive strand RNA synthesis and how RNA capping is regulated. Recent work has begun to provide a conceptual framework for flavivirus RNA replication and capping and shown some surprising roles for genomic RNA during replication and pathogenesis. PMID:23929625

  19. Perfluorocarbon vapor tagging of blasting cap detonators

    DOEpatents

    Dietz, Russell N.; Senum, Gunnar I.

    1981-01-01

    A plug for a blasting cap is made of an elastomer in which is dissolved a perfluorocarbon. The perfluorocarbon is released as a vapor into the ambient over a long period of time to serve as a detectable taggant.

  20. Textures in south polar ice cap #2

    NASA Technical Reports Server (NTRS)

    1998-01-01

    Textures of the south polar permanent residual ice cap and polar layered terrains. This 15 x 14 km area image (frame 7306) is centered near 87 degrees south, 341 degrees west.

    Figure caption from Science Magazine

  1. Textures in south polar ice cap #1

    NASA Technical Reports Server (NTRS)

    1998-01-01

    Textures of the south polar permanent residual ice cap and polar layered terrains. This 30 x 29 km area image (frame 7709) is centered near 87 degrees south, 77 degrees west.

    Figure caption from Science Magazine

  2. The Casimir Energy for the Riemann Caps

    NASA Astrophysics Data System (ADS)

    Palesheva, E. V.; Pecheritsyn, A. A.

    2017-03-01

    The Casimir energy of a massive scalar field on a Riemann cap with the Dirichlet boundary conditions is calculated. The problem is considered in the quasi-stationary approximation. Formulas are derived which are suitable for numerical calculations.

  3. The Casimir Energy for the Riemann Caps

    NASA Astrophysics Data System (ADS)

    Palesheva, E. V.; Pecheritsyn, A. A.

    2017-03-01

    The Casimir energy of a massive scalar field on a Riemann cap with the Dirichlet boundary conditions is calculated. The problem is considered in the quasi-stationary approximation. Formulas are derived which are suitable for numerical calculations.

  4. DESIGN CONSIDERATION INVOLVING ACTIVE SEDIMENT CAPS (PRESENTATION)

    EPA Science Inventory

    When contaminated sediments pose unacceptable risks to human health and the environment, management activities such as removal, treatment, or isolation of contaminated sediments may be required. Various capping designs are being considered for isolating contaminated sediment are...

  5. DESIGN CONSIDERATION INVOLVING ACTIVE SEDIMENT CAPS

    EPA Science Inventory

    When contaminated sediments pose unacceptable risks to human health and the environment, management activities such as removal, treatment, or isolation of contaminated sediments may be required. Various capping designs are being considered for isolating contaminated sediment are...

  6. DESIGN CONSIDERATION INVOLVING ACTIVE SEDIMENT CAPS

    EPA Science Inventory

    When contaminated sediments pose unacceptable risks to human health and the environment, management activities such as removal, treatment, or isolation of contaminated sediments may be required. Various capping designs are being considered for isolating contaminated sediment are...

  7. Chemical synthesis of dinucleotide cap analogs.

    PubMed

    Kore, Anilkumar R; Shanmugasundaram, Muthian

    2014-12-19

    This unit describes a reliable, efficient and general method for the synthesis of standard cap analog (mCAP), m(7)G[5']ppp[5']G, and anti-reverse cap analog (ARCA), m(7,3')(O)G[5']ppp[5']G. The synthesis of required intermediate m(7)GDP or m(2)(7,3'O)GDP has been achieved through regioselective methylation of the corresponding diphosphate using dimethyl sulfate under aqueous conditions. Then, the coupling reaction of m(7)GDP or m(2)(7,3'O)GDP with ImGMP using ZnCl(2)/DMF system affords the corresponding cap analog in good yields. Copyright © 2014 John Wiley & Sons, Inc.

  8. Commercial Crew Program CCiCap Partners

    NASA Image and Video Library

    NASA's Commercial Crew Program and its newest Commercial Crew Integrated Capability (CCiCap) partners are embracing the American spirit as they advance their integrated rocket and spacecraft design...

  9. Enhanced gravitropism of roots with a disrupted cap actin cytoskeleton

    NASA Technical Reports Server (NTRS)

    Hou, Guichuan; Mohamalawari, Deepti R.; Blancaflor, Elison B.

    2003-01-01

    The actin cytoskeleton has been proposed to be a major player in plant gravitropism. However, understanding the role of actin in this process is far from complete. To address this problem, we conducted an analysis of the effect of Latrunculin B (Lat B), a potent actin-disrupting drug, on root gravitropism using various parameters that included detailed curvature kinetics, estimation of gravitropic sensitivity, and monitoring of curvature development after extended clinorotation. Lat B treatment resulted in a promotion of root curvature after a 90 degrees reorientation in three plant species tested. More significantly, the sensitivity of maize (Zea mays) roots to gravity was enhanced after actin disruption, as determined from a comparison of presentation time of Lat B-treated versus untreated roots. A short 10-min gravistimulus followed by extended rotation on a 1-rpm clinostat resulted in extensive gravitropic responses, manifested as curvature that often exceeded 90 degrees. Application of Lat B to the cap or elongation zone of maize roots resulted in the disruption of the actin cytoskeleton, which was confined to the area of localized Lat B application. Only roots with Lat B applied to the cap displayed the strong curvature responses after extended clinorotation. Our study demonstrates that disrupting the actin cytoskeleton in the cap leads to the persistence of a signal established by a previous gravistimulus. Therefore, actin could function in root gravitropism by providing a mechanism to regulate the proliferation of a gravitropic signal originating from the cap to allow the root to attain its correct orientation or set point angle.

  10. Enhanced gravitropism of roots with a disrupted cap actin cytoskeleton

    NASA Technical Reports Server (NTRS)

    Hou, Guichuan; Mohamalawari, Deepti R.; Blancaflor, Elison B.

    2003-01-01

    The actin cytoskeleton has been proposed to be a major player in plant gravitropism. However, understanding the role of actin in this process is far from complete. To address this problem, we conducted an analysis of the effect of Latrunculin B (Lat B), a potent actin-disrupting drug, on root gravitropism using various parameters that included detailed curvature kinetics, estimation of gravitropic sensitivity, and monitoring of curvature development after extended clinorotation. Lat B treatment resulted in a promotion of root curvature after a 90 degrees reorientation in three plant species tested. More significantly, the sensitivity of maize (Zea mays) roots to gravity was enhanced after actin disruption, as determined from a comparison of presentation time of Lat B-treated versus untreated roots. A short 10-min gravistimulus followed by extended rotation on a 1-rpm clinostat resulted in extensive gravitropic responses, manifested as curvature that often exceeded 90 degrees. Application of Lat B to the cap or elongation zone of maize roots resulted in the disruption of the actin cytoskeleton, which was confined to the area of localized Lat B application. Only roots with Lat B applied to the cap displayed the strong curvature responses after extended clinorotation. Our study demonstrates that disrupting the actin cytoskeleton in the cap leads to the persistence of a signal established by a previous gravistimulus. Therefore, actin could function in root gravitropism by providing a mechanism to regulate the proliferation of a gravitropic signal originating from the cap to allow the root to attain its correct orientation or set point angle.

  11. Design and implementation of the CAPS receiver

    NASA Astrophysics Data System (ADS)

    Hu, Yonghui; Hua, Yu; Hou, Lei; Wei, Jingfa; Wu, Jianfeng

    2009-03-01

    In this paper, based on analyses of the Chinese Area Positioning System (CAPS) satellite (GEO satellite) resources and signal properties, the signal power at the port of the receiver antenna is estimated, and the implementation projects are presented for a switching band C to band L CAPS C/A code receiver integrated with GPS receiver suite and for a CAPS dual frequency P code receiver. A microstrip receiving antenna is designed with high sensitivity and wide beam orientation, the RF front end of the C/A code and P code receivers, and a processor is designed for the navigation baseband. A single frequency CAPS C/A code receiver and a CAPS dual frequency P code receiver are built at the same time. A software process flow is provided, and research on relatively key techniques is also conducted, such as signal searching, code loop and carrier loop algorithms, a height assistant algorithm, a dual frequency difference speed measurement technique, a speed measurement technique using a single frequency source with frequency assistance, and a CAPS time correcting algorithm, according to the design frame of the receiver hardware. Research results show that the static plane positioning accuracy of the CAPS C/A code receiver is 20.5-24.6 m, height accuracy is 1.2-12.8 m, speed measurement accuracy is 0.13-0.3 m/s, dynamic plane positioning accuracy is 24.4 m, height accuracy is 3.0 m, and speed measurement accuracy is 0.24 m/s. In the case of C/A code, the timing accuracy is 200 ns, and it is also shown that the positioning accuracy of the CAPS precise code receiver (1 σ) is 5 m from south to north, and 0.8 m from east to west. Finally, research on positioning accuracy is also conducted.

  12. Truncated Dual-Cap Nucleation Site Development

    NASA Technical Reports Server (NTRS)

    Matson, Douglas M.; Sander, Paul J.

    2012-01-01

    During heterogeneous nucleation within a metastable mushy-zone, several geometries for nucleation site development must be considered. Traditional spherical dual cap and crevice models are compared to a truncated dual cap to determine the activation energy and critical cluster growth kinetics in ternary Fe-Cr-Ni steel alloys. Results of activation energy results indicate that nucleation is more probable at grain boundaries within the solid than at the solid-liquid interface.

  13. Secondary capping beams for offshore drilling platforms

    SciTech Connect

    Albaugh, E. K.

    1985-08-13

    A pair of I-shaped elongated girders secured to, and extending outwardly from, the capping beams of a four pile platform, to form cantilever secondary capping beams which support modified self-contained drilling rigs of a size and weight normally installed on eight pile platforms. Rig modifications comprise separation of pump and engine packages, a pipe rack extension, and a novel skidding system.

  14. Fourier spectra from exoplanets with polar caps and ocean glint

    NASA Astrophysics Data System (ADS)

    Visser, P. M.; van de Bult, F. J.

    2015-07-01

    Context. The weak orbital-phase dependent reflection signal of an exoplanet contains information on the planet surface, such as the distribution of continents and oceans on terrestrial planets. This light curve is usually studied in the time domain, but because the signal from a stationary surface is (quasi)periodic, analysis of the Fourier series may provide an alternative, complementary approach. Aims: We study Fourier spectra from reflected light curves for geometrically simple configurations. Depending on its atmospheric properties, a rotating planet in the habitable zone could have circular polar ice caps. Tidally locked planets, on the other hand, may have symmetric circular oceans facing the star. These cases are interesting because the high-albedo contrast at the sharp edges of the ice-sheets and the glint from the host star in the ocean may produce recognizable light curves with orbital periodicity, which could also be interpreted in the Fourier domain. Methods: We derive a simple general expression for the Fourier coefficients of a quasiperiodic light curve in terms of the albedo map of a Lambertian planet surface. Analytic expressions for light curves and their spectra are calculated for idealized situations, and dependence of the spectral peaks on the key parameters inclination, obliquity, and cap size is studied. Results: The ice-scattering and ocean glint contributions can be separated out, because the coefficients for glint are all positive, whereas ice sheets lead to even-numbered, higher harmonics. An in-view polar cap on a planet without axial tilt only produces a single peak. The special situation of edge-on observation, which is important for planets in transit, leads to the most pronounced spectral behavior. Then the respective spectra from planets with a circumventing ocean, a circular ocean (eyeball world), polar caps, and rings, have characteristic power-law tails n-2, n-7/2, n-4, and (-1)n + 1n-2. Conclusions: Promising recently discovered

  15. Lost caps in histological counting methods.

    PubMed

    Hedreen, J C

    1998-03-01

    In methods with the goal of counting objects in a sectioned tissue volume by examining their profiles or segments in the sections, lost caps, i.e., small object fragments unnoticed or missing at the section surfaces, are an unavoidable issue. The problem of lost caps is examined as it applies to four methods for counting in histological sections, the method usually referred to as the Abercrombie correction, the empirical method, the optical disector, and the physical disector. Lost caps are an insoluble problem in the Abercrombie method; the lost caps error correction factor should be incorporated into the Abercrombie equation. Lost caps cancel out in the optical disector. The empirical method logically requires, to avoid lost caps error, either a preliminary blind identification of object segments in the serial sections or identification of segments with reference to adjacent sections in the counting sections. Similarly, the physical disector method requires either a preliminary blind identification of object segments in both look-up and sampling sections, or use of three sections rather than two.

  16. The effect of polar caps on obliquity

    NASA Technical Reports Server (NTRS)

    Lindner, B. L.

    1993-01-01

    Rubincam has shown that the Martian obliquity is dependent on the seasonal polar caps. In particular, Rubincam analytically derived this dependence and showed that the change in obliquity is directly proportional to the seasonal polar cap mass. Rubincam concludes that seasonal friction does not appear to have changed Mars' climate significantly. Using a computer model for the evolution of the Martian atmosphere, Haberle et al. have made a convincing case for the possibility of huge polar caps, about 10 times the mass of the current polar caps, that exist for a significant fraction of the planet's history. Since Rubincam showed that the effect of seasonal friction on obliquity is directly proportional to polar cap mass, a scenario with a ten-fold increase in polar cap mass over a significant fraction of the planet's history would result in a secular increase in Mars' obliquity of perhaps 10 degrees. Hence, the Rubincam conclusion of an insignificant contribution to Mars' climate by seasonal friction may be incorrect. Furthermore, if seasonal friction is an important consideration in the obliquity of Mars, this would significantly alter the predictions of past obliquity.

  17. Nephron induction revisited: from caps to condensates.

    PubMed

    Sariola, Hannu

    2002-01-01

    Conversion of mesenchyme to epithelium in the metanephric kidney is clearly a multimolecular, multistep and partly redundant process. The present short review focuses on a neglected morphological aspect of kidney differentiation: the development of two transitory mesenchymal condensations that precede epithelial differentiation of nephrons. The first appearing condensate covers the tips of the collecting ducts and is termed a cap condensate. In the early kidney rudiment this structure has been referred to as a primary or early condensate. A few cells of the cap condensate (maybe only four to six cells), situated at the lateral edge of the cap, start proliferating rapidly and form a pretubular aggregate (or pretubular condensate), which converts to secretory nephron epithelia and finally segregates to different tubule segments. Throughout nephrogenesis, the cap condensates and pretubular aggregates are clearly distinguishable structures that show only partly overlapping gene expression profiles. Apart from being the source for the pretubular aggregates, the role of the cap condensate is unknown. It is now proposed that the cap regulates ureteric branching morphogenesis.

  18. Lead poisoning

    SciTech Connect

    Rekus, J.F.

    1992-08-01

    Construction workers who weld, cut or blast structural steel coated with lead-based paint are at significant risk of lead poisoning. Although technology to control these exposures may not have existed when the lead standard was promulgated, it is available today. Employers who do not take steps to protect their employees from lead exposure may be cited and fined severely for their failure.

  19. Differential expression of KRT83 regulated by the transcript factor CAP1 in Chinese Tan sheep.

    PubMed

    Liu, Yufang; Kang, Xiaolong; Yang, Wanjie; Xie, Minggui; Zhang, Jibin; Fang, Meiying

    2017-03-08

    Keratin 83 (KRT83) is an important keratin protein in hair development. In this study, expression of KRT83 was compared among different tissues and between 1-month-old lambs and 48-month adult of Chinese Tan sheep, which showed different fleece phenotypes. The results showed that KRT83 was only expressed in skin, and KRT83 mRNA level in skin was significantly higher in Tan lambs than in adult sheep. To further understand the expression regulation of KRT83 by transcription factors in Tan sheep, amplified sequences coving different ranges of KRT83 promoter region were inserted into a pGL3-basic vector and then transfected into sheep primary fibroblast cells. Luciferase assay indicated that the sequence from -218bp to -10bp in the KRT83 promoter induced the highest transcription activity of the vector in the fibroblast cells. Transcription factor adenylate cyclase-associated protein 1 (CAP1) was predicted by online tools within this region. Electrophoretic mobility shift assay (EMSA) confirmed binding of the purified CAP1 protein to the target core region from -88bp to -10bp, because mutation in the target core sequence resulted in failure of CAP1 binding to the target region. Moreover, overexpression of CAP1 protein led to repression of the KRT83 promoter activity in sheep primary fibroblast cells, and expression of CAP1 was lower in lambs than in adult sheep. Therefore, we concluded that CAP1 is a key transcription factor involved in negative regulation of KRT83 expression in Tan sheep skin. Our study provides new insights into the transcriptional regulation of KRT83 and further hints of its critical role in curly hair phenotype in sheep.

  20. Al capping layers for nondestructive x-ray photoelectron spectroscopy analyses of transition-metal nitride thin films

    SciTech Connect

    Greczynski, Grzegorz Hultman, Lars; Petrov, Ivan; Greene, J. E.

    2015-09-15

    X-ray photoelectron spectroscopy (XPS) compositional analyses of materials that have been air exposed typically require ion etching in order to remove contaminated surface layers. However, the etching step can lead to changes in sample surface and near-surface compositions due to preferential elemental sputter ejection and forward recoil implantation; this is a particular problem for metal/gas compounds and alloys such as nitrides and oxides. Here, the authors use TiN as a model system and compare XPS analysis results from three sets of polycrystalline TiN/Si(001) films deposited by reactive magnetron sputtering in a separate vacuum chamber. The films are either (1) air-exposed for ≤10 min prior to insertion into the ultrahigh-vacuum (UHV) XPS system; (2) air-exposed and subject to ion etching, using different ion energies and beam incidence angles, in the XPS chamber prior to analysis; or (3) Al-capped in-situ in the deposition system prior to air-exposure and loading into the XPS instrument. The authors show that thin, 1.5–6.0 nm, Al capping layers provide effective barriers to oxidation and contamination of TiN surfaces, thus allowing nondestructive acquisition of high-resolution core-level spectra representative of clean samples, and, hence, correct bonding assignments. The Ti 2p and N 1s satellite features, which are sensitive to ion bombardment, exhibit high intensities comparable to those obtained from single-crystal TiN/MgO(001) films grown and analyzed in-situ in a UHV XPS system and there is no indication of Al/TiN interfacial reactions. XPS-determined N/Ti concentrations acquired from Al/TiN samples agree very well with Rutherford backscattering and elastic recoil analysis results while ion-etched air-exposed samples exhibit strong N loss due to preferential resputtering. The intensities and shapes of the Ti 2p and N 1s core level signals from Al/TiN/Si(001) samples do not change following long-term (up to 70 days) exposure to ambient conditions

  1. Polar cap potential saturation: An energy conservation perspective

    NASA Astrophysics Data System (ADS)

    Liu, W. William

    2007-07-01

    In the long run, energy entering the magnetosphere from the solar wind must be balanced by energy dissipation in or escape from the system. It then follows that the Joule heating rate in the ionosphere statistically should be bounded from the upside by the solar wind energy input function (e.g., the Perrault-Akasofu parameter). We show that this energy constraint, coupled with some observationally motivated assumptions about the behavior of the auroral oval under escalating solar wind conditions, leads to the prediction of polar cap potential saturation.

  2. [The multifunctional RNA polymerase L protein of non-segmented negative strand RNA viruses catalyzes unique mRNA capping].

    PubMed

    Ogino, Tomoaki

    2014-01-01

    Non-segmented negative strand RNA viruses belonging to the Mononegavirales order possess RNA-dependent RNA polymerase L proteins within viral particles. The L protein is a multifunctional enzyme catalyzing viral RNA synthesis and processing (i.e., mRNA capping, cap methylation, and polyadenylation). Using vesicular stomatitis virus (VSV) as a prototypic model virus, we have shown that the L protein catalyzes the unconventional mRNA capping reaction, which is strikingly different from the eukaryotic reaction. Furthermore, co-transcriptional pre-mRNA capping with the VSV L protein was found to be required for accurate stop?start transcription to synthesize full-length mRNAs in vitro and virus propagation in host cells. This article provides a review of historical and present studies leading to the elucidation of the molecular mechanism of VSV mRNA capping.

  3. Models of the earth's core

    NASA Technical Reports Server (NTRS)

    Stevenson, D. J.

    1981-01-01

    Combined inferences from seismology, high-pressure experiment and theory, geomagnetism, fluid dynamics, and current views of terrestrial planetary evolution lead to models of the earth's core with five basic properties. These are that core formation was contemporaneous with earth accretion; the core is not in chemical equilibrium with the mantle; the outer core is a fluid iron alloy containing significant quantities of lighter elements and is probably almost adiabatic and compositionally uniform; the more iron-rich inner solid core is a consequence of partial freezing of the outer core, and the energy release from this process sustains the earth's magnetic field; and the thermodynamic properties of the core are well constrained by the application of liquid-state theory to seismic and labroatory data.

  4. Models of the earth's core

    NASA Technical Reports Server (NTRS)

    Stevenson, D. J.

    1981-01-01

    Combined inferences from seismology, high-pressure experiment and theory, geomagnetism, fluid dynamics, and current views of terrestrial planetary evolution lead to models of the earth's core with five basic properties. These are that core formation was contemporaneous with earth accretion; the core is not in chemical equilibrium with the mantle; the outer core is a fluid iron alloy containing significant quantities of lighter elements and is probably almost adiabatic and compositionally uniform; the more iron-rich inner solid core is a consequence of partial freezing of the outer core, and the energy release from this process sustains the earth's magnetic field; and the thermodynamic properties of the core are well constrained by the application of liquid-state theory to seismic and labroatory data.

  5. Models of the Earth's Core.

    PubMed

    Stevenson, D J

    1981-11-06

    Combined inferences from seismology, high-pressure experiment and theory, geomagnetism, fluid dynamics, and current views of terrestrial planetary evolution lead to models of the earth's core with the following properties. Core formation was contemporaneous with earth accretion; the core is not in chemical equilibrium with the mantle; the outer core is a fluid iron alloy containing significant quantities of lighter elements and is probably almost adiabatic and compositionally uniform; the more iron-rich inner solid core is a consequence of partial freezing of the outer core, and the energy release from this process sustains the earth's magnetic field; and the thermodynamic properties of the core are well constrained by the application of liquid-state theory to seismic and laboratory data.

  6. Fluid core size of Mars from detection of the solar tide.

    PubMed

    Yoder, C F; Konopliv, A S; Yuan, D N; Standish, E M; Folkner, W M

    2003-04-11

    The solar tidal deformation of Mars, measured by its k2 potential Love number, has been obtained from an analysis of Mars Global Surveyor radio tracking. The observed k2 of 0.153 +/- 0.017 is large enough to rule out a solid iron core and so indicates that at least the outer part of the core is liquid. The inferred core radius is between 1520 and 1840 kilometers and is independent of many interior properties, although partial melt of the mantle is one factor that could reduce core size. Ice-cap mass changes can be deduced from the seasonal variations in air pressure and the odd gravity harmonic J3, given knowledge of cap mass distribution with latitude. The south cap seasonal mass change is about 30 to 40% larger than that of the north cap.

  7. Fluid core size of Mars from detection of the solar tide

    NASA Technical Reports Server (NTRS)

    Yoder, C. F.; Konopliv, A. S.; Yuan, D. N.; Standish, E. M.; Folkner, W. M.

    2003-01-01

    The solar tidal deformation of Mars, measured by its k2 potential Love number, has been obtained from an analysis of Mars Global Surveyor radio tracking. The observed k2 of 0.153 +/- 0.017 is large enough to rule out a solid iron core and so indicates that at least the outer part of the core is liquid. The inferred core radius is between 1520 and 1840 kilometers and is independent of many interior properties, although partial melt of the mantle is one factor that could reduce core size. Ice-cap mass changes can be deduced from the seasonal variations in air pressure and the odd gravity harmonic J3, given knowledge of cap mass distribution with latitude. The south cap seasonal mass change is about 30 to 40% larger than that of the north cap.

  8. Fluid Core Size of Mars from Detection of the Solar Tide

    NASA Astrophysics Data System (ADS)

    Yoder, C. F.; Konopliv, A. S.; Yuan, D. N.; Standish, E. M.; Folkner, W. M.

    2003-04-01

    The solar tidal deformation of Mars, measured by its k2 potential Love number, has been obtained from an analysis of Mars Global Surveyor radio tracking. The observed k2 of 0.153 +/- 0.017 is large enough to rule out a solid iron core and so indicates that at least the outer part of the core is liquid. The inferred core radius is between 1520 and 1840 kilometers and is independent of many interior properties, although partial melt of the mantle is one factor that could reduce core size. Ice-cap mass changes can be deduced from the seasonal variations in air pressure and the odd gravity harmonic J3, given knowledge of cap mass distribution with latitude. The south cap seasonal mass change is about 30 to 40% larger than that of the north cap.

  9. Fluid core size of Mars from detection of the solar tide

    NASA Technical Reports Server (NTRS)

    Yoder, C. F.; Konopliv, A. S.; Yuan, D. N.; Standish, E. M.; Folkner, W. M.

    2003-01-01

    The solar tidal deformation of Mars, measured by its k2 potential Love number, has been obtained from an analysis of Mars Global Surveyor radio tracking. The observed k2 of 0.153 +/- 0.017 is large enough to rule out a solid iron core and so indicates that at least the outer part of the core is liquid. The inferred core radius is between 1520 and 1840 kilometers and is independent of many interior properties, although partial melt of the mantle is one factor that could reduce core size. Ice-cap mass changes can be deduced from the seasonal variations in air pressure and the odd gravity harmonic J3, given knowledge of cap mass distribution with latitude. The south cap seasonal mass change is about 30 to 40% larger than that of the north cap.

  10. 24. A CORE WORKER DISPLAYS THE CORE BOX AND CORES ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    24. A CORE WORKER DISPLAYS THE CORE BOX AND CORES FOR A BRASS GATE VALVE BODY MADE ON A CORE BOX, CA. 1950. - Stockham Pipe & Fittings Company, 4000 Tenth Avenue North, Birmingham, Jefferson County, AL

  11. GaAs nanowires with oxidation-proof arsenic capping for the growth of an epitaxial shell.

    PubMed

    Guan, X; Becdelievre, J; Benali, A; Botella, C; Grenet, G; Regreny, P; Chauvin, N; Blanchard, N P; Jaurand, X; Saint-Girons, G; Bachelet, R; Gendry, M; Penuelas, J

    2016-08-25

    We propose an arsenic-capping/decapping method, allowing the growth of an epitaxial shell around the GaAs nanowire (NW) core which is exposed to an ambient atmosphere, and without the introduction of impurities. Self-catalyzed GaAs NW arrays were firstly grown on Si(111) substrates by solid-source molecular beam epitaxy. Aiming for protecting the active surface of the GaAs NW core, the arsenic-capping/decapping method has been applied. To validate the effect of this method, different core/shell NWs have been fabricated. Analyses highlight the benefit of the As capping-decapping method for further epitaxial shell growth: an epitaxial shell with a smooth surface is achieved in the case of As-capped-decapped GaAs NWs, comparable to the in situ grown GaAs/AlGaAs NWs. This As capping method opens a way for the epitaxial growth of heterogeneous material shells such as functional oxides using different reactors.

  12. 47 CFR 61.43 - Annual price cap filings required.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 3 2010-10-01 2010-10-01 false Annual price cap filings required. 61.43... (CONTINUED) TARIFFS General Rules for Dominant Carriers § 61.43 Annual price cap filings required. Carriers subject to price cap regulation shall submit annual price cap tariff filings that propose rates for the...

  13. 49 CFR 230.41 - Flexible staybolts with caps.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Flexible staybolts with caps. 230.41 Section 230... Appurtenances Staybolts § 230.41 Flexible staybolts with caps. (a) General. Flexible staybolts with caps shall have their caps removed during every 5th annual inspection for the purpose of inspecting the bolts for...

  14. Characterization of luminescence properties of V2O5-capped ZnSe nanowires.

    PubMed

    Kim, Hyunsu; Jin, Changhyun; Lee, Chongmu

    2011-08-01

    ZnSe-core/V2O5-shell nanowires were synthesized by the thermal evaporation of ZnSe powders on gold-coated Si (100) substrates followed by the sputter depositon of V2O5. Scanning electron microscopic images showed that the core-shell nanowires were a few tens to a few hundreds of nanometers in diameter and a few hundreds of micrometers in length. Transmission electron microscopy and X-ray diffraction analyses revealed that the core and shell of the core-shell nanowires were single crystal wurtzite-structured ZnSe and amorphous V2O5, respectively. Photoluminescence measurement showed that the core-shell nanowires as-synthesized or annealed in an oxidative atmosphere had a green emission band centered at around 520 nm whereas the as-synthesized ZnSe nanowires and the ZnSe-core/V2O5-shell nanowires annealed in a reducing atmosphere had a yellow emission band centered at around 590 nm. Our results also showed that V2O5 capping with an optimal thickness and subsequent annealing in a reducing atmosphere could significantly enhance the emission intensity of the ZnSe nanowires. In addition, the origins of the enhancement in intensity and the blue shift of the major emission by V2O5 capping are discussed.

  15. Preparation and applications of a variety of fluoroalkyl end-capped oligomer/hydroxyapatite composites.

    PubMed

    Takashima, Hiroki; Iwaki, Ken-Ichi; Furukuwa, Rika; Takishita, Katsuhisa; Sawada, Hideo

    2008-04-15

    A variety of fluoroalkyl end-capped oligomers were applied to the preparation of fluorinated oligomer/hydroxyapatite (HAp) composites (particle size: 38-356 nm), which exhibit a good dispersibility in water and traditional organic solvents. These fluoroalkyl end-capped oligomer/HAp composites were easily prepared by the reactions of disodium hydrogen phosphate and calcium chloride in the presence of self-assembled molecular aggregates formed by fluoroalkyl end-capped oligomers in aqueous solutions. In these fluorinated HAp composites thus obtained, fluoroalkyl end-capped acrylic acid oligomers and 2-methacryloyloxyethanesulfonic acid oligomer/HAp nanocomposites afforded transparent colorless solutions toward water; however, fluoroalkyl end-capped N,N-dimethylacrylamide oligomer and acryloylmorpholine oligomer were found to afford transparent colorless solutions with trace amounts of white-colored HAp precipitants under similar conditions. HAp could be encapsulated more effectively into fluorinated 2-methacryloyloxyethanesulfonic acid oligomeric aggregate cores to afford colloidal stable fluorinated oligomer/HAp composites, compared to that of fluorinated acrylic acid oligomers. These fluorinated oligomer/HAp composites were applied to the surface modification of glass and PVA to exhibit a good oleophobicity imparted by fluorine. HAp formation was newly observed on the modified polyethylene terephthalate film surface treated with fluorinated 2-methacryloyloxyethanesulfonic acid oligomers and acrylic acid oligomer/HAp composites by soaking these films into the simulated body fluid.

  16. Measurement of fibrous cap thickness in atherosclerotic plaques by spatiotemporal analysis of laser speckle images

    NASA Astrophysics Data System (ADS)

    Nadkarni, Seemantini K.; Bilenca, Alberto; Bouma, Brett E.; Tearney, Guillermo J.

    2006-03-01

    Necrotic-core fibroatheromas (NCFA) with thin, mechanically weak fibrous caps overlying lipid cores comprise the majority of plaques that rupture and cause acute myocardial infarction. Laser speckle imaging (LSI) has been recently demonstrated to enable atherosclerotic plaque characterization with high accuracy. We investigate spatio-temporal analysis of LSI data, in conjunction with diffusion theory and Monte Carlo modeling of light transport, to estimate fibrous cap thickness in NCFAs. Time-varying laser speckle images of 20 NCFAs are selected for analysis. Spatio-temporal intensity fluctuations are analyzed by exponential fitting of the windowed normalized cross-correlation of sequential laser speckle patterns to obtain the speckle decorrelation time constant, τ(ρ), as a function of distance ρ from the source entry location. The distance, ρ‧, at which τ(ρ) dropped to 65% of its maximum value is recorded. Diffusion theory and Monte Carlo models are utilized to estimate the maximum photon penetration depth, zmax(ρ‧), for a distance equal to ρ‧, measured from LSI. Measurements of zmax(ρ‧) correlate well with histological measurements of fibrous cap thickness (R=0.78,p<0.0001), and paired t-tests show no significant difference between the groups (p=0.4). These results demonstrate that spatio-temporal LSI may allow the estimation of fibrous cap thickness in NCFAs, which is an important predictor of plaque stability.

  17. O+ transport across the polar cap

    NASA Astrophysics Data System (ADS)

    Elliott, H. A.; Jahn, J.; Pollock, C. J.; Moore, T. E.; Horwitz, J. L.

    2006-12-01

    The plasma sheet, inner magnetosphere, and high latitude magnetosphere all contain significant amounts of O+ ions during active times. Singly charged oxygen ions unambiguously come from the ionosphere making them an excellent tracer species. As the solar wind dynamic pressure increases, the O+ density in the in the cleft, high altitude polar cap, and plasma sheet also increases. We test the "cleft ion fountain" model, which asserts that O+ ions escape from the cleft, cross the polar cap, and then enter the plasma sheet against a mo of outflows originating from the entire polar cap. We use observations of O+ transport across the polar cap from TIDE polar cap ion outflow measurements. The Tsyganenko magnetic field model, driven with ACE solar wind parameters is used to provide magnetic mapping and organization of the observations. We calculate the distance between the cleft and the foot-points of magnetic field lines mapped from the Polar spacecraft along the noon-midnight meridian. Using the observed outflow speed and magnetic field line length we calculate travel time for the ions. We then plot the distance from the cleft versus the travel time for an entire pass. For O+ this plot is quite linear, and the slope of the line is the average convection speed of the magnetic field lines across the polar cap. The convection speed we determined is consistent with the convection speed measured in the ionosphere. We conclude that O+ ions emanating principally from the cleft are transported across the polar cap, and these O+ ions have access to the ring current and plasma sheet.

  18. In vitro capping and transcription of rhabdoviruses.

    PubMed

    Ogino, Tomoaki

    2013-02-01

    The RNA-dependent RNA polymerase L protein of vesicular stomatitis virus (VSV), a prototypic nonsegmented negative strand (NNS) RNA virus classified into the Rhabdoviridae family, has been used to investigate the fundamental molecular mechanisms of NNS RNA viral mRNA synthesis and processing. In vitro studies on mRNA cap formation with the VSV L protein eventually led to the discovery of the unconventional mRNA capping pathway catalyzed by the guanosine 5'-triphosphatase and RNA:GDP polyribonucleotidyltransferase (PRNTase) activities. The PRNTase activity is a novel enzymatic activity, which transfers 5'-monophosphorylated (p-) RNA from 5'-triphosphorylated (ppp-) RNA to GDP to form 5'-capped RNA (GpppRNA) in a viral mRNA-start sequence-dependent manner. This unconventional capping (pRNA transfer) reaction with PRNTase can be experimentally distinguished from the conventional capping (GMP transfer) reaction with eukaryotic GTP:RNA guanylyltransferase (GTase) on the basis of the following differences in their substrate specificity for the cap formation: PRNTase uses GDP and pppRNA, but not ppRNA, whereas GTase employs GTP, but not GDP, and ppRNA. The pRNA transfer reaction with PRNTase proceeds through a covalent enzyme-pRNA intermediate with a phosphoamide bond. Hence, to prove the PRNTase activity, it is necessary to demonstrate the following consecutive steps separately: (1) the enzyme forms a covalent enzyme-pRNA intermediate, and (2) the intermediate transfers pRNA to GDP. This article describes the methods for in vitro transcription and capping with the recombinant VSV L protein, which permit detailed characterization of its enzymatic reactions and mapping of active sites of its enzymatic domains. It is expected that these systems are adaptable to rhabdoviruses and, by extension, other NNS RNA viruses belonging to different families.

  19. Subannual layer variability in Greenland firn cores

    NASA Astrophysics Data System (ADS)

    Kjær, Helle Astrid; Vallelonga, Paul; Vinther, Bo; Winstrup, Mai; Simonsen, Marius; Maffezzoli, Niccoló; Jensen, Camilla Marie

    2017-04-01

    Ice cores are used to infer information about the past and modern techniques allow for high resolution (< cm) continuous flow analysis (CFA) of the ice. Such analysis is often used to inform on annual layers to constrain dating of ice cores, but can also be extended to provide information on sub-annual deposition patterns. In this study we use available high resolution data from multiple shallow cores around Greenland to investigate the seasonality and trends in the most often continuously measured components sodium, insoluble dust, calcium, ammonium and conductivity (or acidity) from 1800 AD to today. We evaluate the similarities and differences between the records and discuss the causes from different sources and transport to deposition and post-deposition effects over differences in measurement set up. Further we add to the array of cores already published with measurements from the newly drilled ReCAP ice core from a coastal ice cap in eastern Greenland and from a shallow core drilled at the high accumulation site at the Greenland South Dome.

  20. Lead Test

    MedlinePlus

    ... the condition. Children should also be assessed for iron deficiency and general nutrition consistent with AAP guidelines. BLLs ... raised blood lead concentrations should be tested for iron deficiency . Each person eliminates lead differently. Thus, laboratory tests ...

  1. Lead Poisoning

    MedlinePlus

    ... through deteriorating paint, household dust, bare soil, air, drinking water, food, ceramics, home remedies, hair dyes and other ... an elevated blood lead level can easily result. Drinking water can also sometimes contribute to elevated blood lead ...

  2. Science goals for a Mars Polar Cap subsurface mission : optical approaches for investigations of inclusions in ice

    NASA Technical Reports Server (NTRS)

    Carsey, Frank; Mogensen, Claus T.; Behar, Alberto; Engelhardt, Hermann; Lane, Arthur L.

    2002-01-01

    The Mars Polar Caps are highly interesting features of Mars and have received much recent attention with new and exciting data on morphology, basal units, and layered outcroppings. We have examined the climatological, glaciological, and geological issues associated with a subsurface exploration of the Mars North Polar Cap and have determined that a finescale optical examination of ice in a borehole, to examine the stratigraphy, geochemistry and geochronology of the ice, is feasible. This information will enable reconstruction of the development of the cap as well as prediction of the properties of its ice. We present visible imagery taken of dust inclusions in archived Greenland ice cores as well as in-situ images of accreted lithologic inclusions in West Antarctica, and we argue for use of this kind of data in Mars climate reconstruction as has been successful with Greenland and Antarctic ice core analysis. .

  3. Science goals for a Mars Polar Cap subsurface mission : optical approaches for investiagations of inclusions in ice

    NASA Technical Reports Server (NTRS)

    Mogensen, Claus T.; Carsey, Frank D.; Behar, Alberto; Engelhardt, Hermann; Lane, Arthur L.

    2002-01-01

    The Mars Polar Caps are highly interesting features of Mars and have received much recent attention with new and exciting data on morphology, basal units, and layered outcroppings. We have examined the climatological, glaciological, and geological issues associated with a subsurface exploration of the Mars North Polar Cap and have determined that a finescale optical examination of ice in a borehole, to examine the stratigraphy, geochemistry and geochronology of the ice, is feasible. This information will enable reconstruction of the development of the cap as well as predication of the properties of its ice. We present visible imagery taken of dust inclusions in archived Greenland ice cores as well as in-situ images of accreted lithologic inclusions in West Antarctica, and we argue for use of this kind of data in Mars climate reconstruction as has been successful with Greenland and Antarctic ice core anlaysis.

  4. Science goals for a Mars Polar Cap subsurface mission : optical approaches for investiagations of inclusions in ice

    NASA Technical Reports Server (NTRS)

    Mogensen, Claus T.; Carsey, Frank D.; Behar, Alberto; Engelhardt, Hermann; Lane, Arthur L.

    2002-01-01

    The Mars Polar Caps are highly interesting features of Mars and have received much recent attention with new and exciting data on morphology, basal units, and layered outcroppings. We have examined the climatological, glaciological, and geological issues associated with a subsurface exploration of the Mars North Polar Cap and have determined that a finescale optical examination of ice in a borehole, to examine the stratigraphy, geochemistry and geochronology of the ice, is feasible. This information will enable reconstruction of the development of the cap as well as predication of the properties of its ice. We present visible imagery taken of dust inclusions in archived Greenland ice cores as well as in-situ images of accreted lithologic inclusions in West Antarctica, and we argue for use of this kind of data in Mars climate reconstruction as has been successful with Greenland and Antarctic ice core anlaysis.

  5. Science goals for a Mars Polar Cap subsurface mission : optical approaches for investigations of inclusions in ice

    NASA Technical Reports Server (NTRS)

    Carsey, Frank; Mogensen, Claus T.; Behar, Alberto; Engelhardt, Hermann; Lane, Arthur L.

    2002-01-01

    The Mars Polar Caps are highly interesting features of Mars and have received much recent attention with new and exciting data on morphology, basal units, and layered outcroppings. We have examined the climatological, glaciological, and geological issues associated with a subsurface exploration of the Mars North Polar Cap and have determined that a finescale optical examination of ice in a borehole, to examine the stratigraphy, geochemistry and geochronology of the ice, is feasible. This information will enable reconstruction of the development of the cap as well as prediction of the properties of its ice. We present visible imagery taken of dust inclusions in archived Greenland ice cores as well as in-situ images of accreted lithologic inclusions in West Antarctica, and we argue for use of this kind of data in Mars climate reconstruction as has been successful with Greenland and Antarctic ice core analysis. .

  6. Actin capping proteins, CapZ (β-actinin) and tropomodulin in amphioxus striated muscle.

    PubMed

    Bao, Yulong; Kake, Takei; Hanashima, Akira; Nomiya, Yui; Kubokawa, Kaoru; Kimura, Sumiko

    2012-11-15

    CapZ (β-actinin) and tropomodulin (Tmod) are capping proteins involved in the maintenance of thin filaments in vertebrate skeletal muscles. In this study, we focused on amphioxus, the most primitive chordate. We searched for CapZ and Tmod genes in the amphioxus genome and determined their primary structures. Amphioxus possess one CapZα gene (CAPZA) and one CapZβ gene (CAPZB), and the transcripts of these genes were found to be 67%-85% identical to those of human CapZ genes. On the other hand, amphioxus contain one Tmod gene (TMOD), and the product of this gene has an identity of approximately 50% with human Tmod genes 1-4. However, helix 2 of amphioxus Tmod, which is involved in protein-binding to tropomyosin, was highly conserved with approximately 74% identity to human Tmod genes. Western blotting indicated the presence of CapZ and Tmod in the striated muscle of amphioxus. These results suggest that unlike most of vertebrates, such as fish, amphibian, bird, and mammal, CapZ from amphioxus striated muscle is derived from two genes CAPZA and CAPZB, and Tmod is derived from one TMOD gene.

  7. Polar cap precursor of nightside auroral oval intensifications using polar cap arcs

    NASA Astrophysics Data System (ADS)

    Zou, Ying; Nishimura, Yukitoshi; Lyons, Larry R.; Donovan, Eric F.; Shiokawa, Kazuo; Ruohoniemi, J. Michael; McWilliams, Kathryn A.; Nishitani, Nozomu

    2015-12-01

    Recent radar and optical observations suggested that localized fast flows in the polar cap precede disturbances within the nightside auroral oval. However, how commonly this connection occurs has been difficult to examine due to limited coverage of radar flow measurements and diffuse and dim nature of airglow patches. Polar cap arcs are also associated with fast flows in the polar cap and appear much brighter than patches, allowing evaluation of the interaction between polar cap structures and nightside aurora more definitively. We have surveyed data during six winter seasons and selected quasi-steady polar cap arcs lasting >1 h. Thirty-four arcs are found, and for the majority (~85%) of them, as they extend equatorward from high latitude, their contact with the nightside auroral poleward boundary is associated with new and substantial intensifications within the oval. These intensifications are localized (< ~1 h magnetic local time (MLT)) and statistically occur within 10 min and ±1 h MLT from the contact. They appear as poleward boundary intensifications in a thick auroral oval or an intensification of the only resolvable arc within a thin oval, and the latter can also exhibit substantial poleward expansion. When radar echoes are available, they corroborate the association of polar cap arcs with localized enhanced antisunward flows. That the observed oval intensifications are major disturbances that only occur after the impingement of polar cap arcs and near the contact longitude suggest that they are triggered by localized fast flows coming from deep in the polar cap.

  8. How does the antagonism between capping and anti-capping proteins affect actin network dynamics?

    NASA Astrophysics Data System (ADS)

    Hu, Longhua; Papoian, Garegin A.

    2011-09-01

    Actin-based cell motility is essential to many biological processes. We built a simplified, three-dimensional computational model and subsequently performed stochastic simulations to study the growth dynamics of lamellipodia-like branched networks. In this work, we shed light on the antagonism between capping and anti-capping proteins in regulating actin dynamics in the filamentous network. We discuss detailed mechanisms by which capping and anti-capping proteins affect the protrusion speed of the actin network and the rate of nucleation of filaments. We computed a phase diagram showing the regimes of motility enhancement and inhibition by these proteins. Our work shows that the effects of capping and anti-capping proteins are mainly transmitted by modulation of the filamentous network density and local availability of monomeric actin. We discovered that the combination of the capping/anti-capping regulatory network with nucleation-promoting proteins introduces robustness and redundancy in cell motility machinery, allowing the cell to easily achieve maximal protrusion speeds under a broader set of conditions. Finally, we discuss distributions of filament lengths under various conditions and speculate on their potential implication for the emergence of filopodia from the lamellipodial network.

  9. The Prentif contraceptive cervical cap: acceptability aspects and their implications for future cap design.

    PubMed

    Koch, J P

    1982-02-01

    Patients in a private gynecological practice were offered the Prentif contraceptive cervical cap. The first 413 acceptors were sent a questionnaire covering in detail many of the aspects of their experience. The 371 responses contained a wealth of information concerned with safety, effectiveness and acceptability. Safety and effectiveness are dealt with in the companion article preceding, while the less serious risk factors that reduce the acceptability of the Prentif cap are presented and discussed herein. In order of descending frequency, these factors include: odor; difficulty removing; discomfort to partner; difficulty inserting; dislike of spermicide; discomfort to self; urinary discomforts; vaginal infections; vaginal discharge; and vaginal itching. The most attractive features of the cap, as compared with the diaphragm, were: increased convenience; greater safety; less interference with spontaneity; increased frequency of intercourse; and increased libido. Despite multiple problems with Prentif caps, 67.4% of the cap recipients were still using their caps after one year. However, this was among a select group of highly motivated women of above-average intelligence. The causes of cap acceptability problems are discussed along with probable future improvements in cap design that may solve them.

  10. Storage of cellular 5' mRNA caps in P bodies for viral cap-snatching.

    PubMed

    Mir, M A; Duran, W A; Hjelle, B L; Ye, C; Panganiban, A T

    2008-12-09

    The minus strand and ambisense segmented RNA viruses include multiple important human pathogens and are divided into three families, the Orthomyxoviridae, the Bunyaviridae, and the Arenaviridae. These viruses all initiate viral transcription through the process of "cap-snatching," which involves the acquisition of capped 5' oligonucleotides from cellular mRNA. Hantaviruses are emerging pathogenic viruses of the Bunyaviridae family that replicate in the cytoplasm of infected cells. Cellular mRNAs can be actively translated in polysomes or physically sequestered in cytoplasmic processing bodies (P bodies) where they are degraded or stored for subsequent translation. Here we show that the hantavirus nucleocapsid protein binds with high affinity to the 5' cap of cellular mRNAs, protecting the 5' cap from degradation. We also show that the hantavirus nucleocapsid protein accumulates in P bodies, where it sequesters protected 5' caps. P bodies then serve as a pool of primers during the initiation of viral mRNA synthesis by the viral polymerase. We propose that minus strand segmented viruses replicating in the cytoplasm have co-opted the normal degradation machinery of P bodies for storage of cellular caps. Our data also indicate that modification of the cap-snatching model is warranted to include a role for the nucleocapsid protein in cap acquisition and storage.

  11. CAP - JET PROPULSION LABORATORY CONTAMINATION ANALYSIS PROGRAM

    NASA Technical Reports Server (NTRS)

    Millard, J. M.

    1994-01-01

    The Jet Propulsion Laboratory Contamination Analysis Program (CAP) is a generalized transient executive analysis computer code which solves realistic mass transport problems in the free molecular flow environment. These transport problems involve mass flux from surface source emission and re-emission, venting, and engine emission. CAP solution capability allows for one-bounce mass reflections if required. CAP was developed to solve thin-film contamination problems in the free molecular flow environment, the intent being to provide a powerful analytic tool for evaluating spacecraft contamination problems. The solution procedure uses an enclosure method based on a lumped-parameter multinodal approach with mass exchange between nodes. Transient solutions are computed by the finite difference Euler method. First-order rate theory is used to represent surface emission and reemission (user care must be taken to insure the problem is appropriate for such behavior), and all surface emission and reflections are assumed diffuse. CAP does not include the effects of post-deposition chemistry or interaction with the ambient atmosphere. CAP reads in a model represented by a multiple-block data stream. CAP allows the user to edit the input data stream and stack sequential editing operations (or cases) in order to make complex changes in behavior (surface temperatures, engine start-up and shut-down, etc.) in a single run if desired. The eight data blocks which make up the input data stream consist of problem control parameters, nodal data (area, temperature, mass, etc.), engine or vent distribution factors (based upon plume definitions), geometric configuration factors (diffuse surface emission), surface capture coefficient tables, source emission rate constant tables, reemission rate constant tables, and partial node to body collapse capability (for deposition rates only). The user must generate this data stream, since neither the problem-specific geometric relationships, the

  12. Impact of Vial Capping on Residual Seal Force and Container Closure Integrity.

    PubMed

    Mathaes, Roman; Mahler, Hanns-Christian; Roggo, Yves; Ovadia, Robert; Lam, Philippe; Stauch, Oliver; Vogt, Martin; Roehl, Holger; Huwyler, Joerg; Mohl, Silke; Streubel, Alexander

    2016-01-01

    The vial capping process is a critical unit operation during drug product manufacturing, as it could possibly generate cosmetic defects or even affect container closure integrity. Yet there is significant variability in capping equipment and processes, and their relation to potential defects or container closure integrity has not been thoroughly studied. In this study we applied several methods-residual seal force tester, a self-developed system of a piezo force sensor measurement, and computed tomography-to characterize different container closure system combinations that had been sealed using different capping process parameter settings. Additionally, container closure integrity of these samples was measured using helium leakage (physical container closure integrity) and compared to characterization data. The different capping equipment settings lead to residual seal force values from 7 to 115 N. High residual seal force values were achieved with high capping pre-compression force and a short distance between the capping plate and plunge. The choice of container closure system influenced the obtained residual seal force values. The residual seal force tester and piezoelectric measurements showed similar trends. All vials passed physical container closure integrity testing, and no stopper rupture was seen with any of the settings applied, suggesting that container closure integrity was warranted for the studied container closure system with the chosen capping setting ranges. The vial capping process is a critical unit operation during drug product manufacturing, as it could possibly generate cosmetic defects or even affect container closure integrity. Yet there is significant variability in capping equipment and processes, and their relation to potential defects or container closure integrity has not been thoroughly studied. In this study we applied several methods-residual seal force tester, a self-developed system of a piezo force sensor measurement, and

  13. Visual performance for trip hazard detection when using incandescent and led miner cap lamps.

    PubMed

    Sammarco, John J; Gallagher, Sean; Reyes, Miguel

    2010-04-01

    Accident data for 2003-2007 indicate that slip, trip, and falls (STFs) are the second leading accident class (17.8%, n=2,441) of lost-time injuries in underground mining. Proper lighting plays a critical role in enabling miners to detect STF hazards in this environment. Often, the only lighting available to the miner is from a cap lamp worn on the miner's helmet. The focus of this research was to determine if the spectral content of light from light-emitting diode (LED) cap lamps enabled visual performance improvements for the detection of tripping hazards as compared to incandescent cap lamps that are traditionally used in underground mining. A secondary objective was to determine the effects of aging on visual performance. The visual performance of 30 subjects was quantified by measuring each subject's speed and accuracy in detecting objects positioned on the floor both in the near field, at 1.83 meters, and far field, at 3.66 meters. Near field objects were positioned at 0 degrees and +/-20 degrees off axis, while far field objects were positioned at 0 degrees and +/-10 degrees off axis. Three age groups were designated: group A consisted of subjects 18 to 25 years old, group B consisted of subjects 40 to 50 years old, and group C consisted of subjects 51 years and older. Results of the visual performance comparison for a commercially available LED, a prototype LED, and an incandescent cap lamp indicate that the location of objects on the floor, the type of cap lamp used, and subject age all had significant influences on the time required to identify potential trip hazards. The LED-based cap lamps enabled detection times that were an average of 0.96 seconds faster compared to the incandescent cap lamp. Use of the LED cap lamps resulted in average detection times that were about 13.6% faster than those recorded for the incandescent cap lamp. The visual performance differences between the commercially available LED and prototype LED cap lamp were not statistically

  14. Eddy intrustion of hot plasma into the polar cap and formation of polar-cap arcs

    NASA Technical Reports Server (NTRS)

    Chiu, Y. T.; Gorney, D. J.

    1983-01-01

    Under the simple postulate that multiple large scale detachable magnetospheric convection eddies can exist in the vicinity of the convection reversal boundary and in the polar cap, by Kelvin-Helmholtz instability or otherwise, it is shown that a number of seemingly disconnected plasma and electric field observations in the polar cap can be organized into a theory of magnetosheath and plasmasheet plasma intrusion into the polar cap. Current theory of inverted V structures then predicts existence of similar, but weaker, structures at the eddy convection reversal boundaries in the polar cap. A possible consequence is that the polar cap auroras are natural offshoots from discrete oval arcs and evidently are formed by similar processes. The two arc systems can occassionally produce an optical image in the form of the theta aurora.

  15. Sensitivity, stability and future evolution of the world's northernmost ice cap, Hans Tausen Iskappe (Greenland)

    NASA Astrophysics Data System (ADS)

    Zekollari, Harry; Huybrechts, Philippe; Noël, Brice; van de Berg, Willem Jan; van den Broeke, Michiel R.

    2017-03-01

    In this study the dynamics and sensitivity of Hans Tausen Iskappe (western Peary Land, Greenland) to climatic forcing is investigated with a coupled ice flow-mass balance model. The surface mass balance (SMB) is calculated from a precipitation field obtained from the Regional Atmospheric Climate Model (RACMO2.3), while runoff is calculated from a positive-degree-day runoff-retention model. For the ice flow a 3-D higher-order thermomechanical model is used, which is run at a 250 m resolution. A higher-order solution is needed to accurately represent the ice flow in the outlet glaciers. Under 1961-1990 climatic conditions a steady-state ice cap is obtained that is overall similar in geometry to the present-day ice cap. Ice thickness, temperature and flow velocity in the interior agree well with observations. For the outlet glaciers a reasonable agreement with temperature and ice thickness measurements can be obtained with an additional heat source related to infiltrating meltwater. The simulations indicate that the SMB-elevation feedback has a major effect on the ice cap response time and stability. This causes the southern part of the ice cap to be extremely sensitive to a change in climatic conditions and leads to thresholds in the ice cap evolution. Under constant 2005-2014 climatic conditions the entire southern part of the ice cap cannot be sustained, and the ice cap loses about 80 % of its present-day volume. The projected loss of surrounding permanent sea ice and resultant precipitation increase may attenuate the future mass loss but will be insufficient to preserve the present-day ice cap for most scenarios. In a warmer and wetter climate the ice margin will retreat, while the interior is projected to thicken, leading to a steeper ice cap, in line with the present-day observed trends. For intermediate- (+4 °C) and high- warming scenarios (+8 °C) the ice cap is projected to disappear around AD 2400 and 2200 respectively, almost independent of the projected

  16. O transport across the polar cap

    NASA Astrophysics Data System (ADS)

    Elliott, H. A.; Jahn, J.-M.; Pollock, C. J.; Moore, T. E.; Horwitz, J. L.

    2007-09-01

    The plasma sheet, inner magnetosphere, and high-latitude magnetosphere all contain significant amounts of O ions during active times. Singly charged oxygen ions unambiguously come from the ionosphere, making them an excellent tracer species. We test the cleft ion fountain theory, which asserts that O ions escape from the cleft, cross the polar cap, and then enter the plasma sheet. Statistical studies of O density in the cleft, high-altitude polar cap, and plasma sheet all indicate that the O density increases with increasing solar wind dynamic pressure. In order to examine O transport more directly, we use polar cap ion outflow measurements and the 2001 Tsyganenko magnetic field model driven with advanced composition explorer (ACE) solar wind parameters. We calculate the distance between the cleft and the ionospheric footpoints of magnetic field lines mapped from the polar spacecraft along the noon midnight meridian. Using the observed outflow speed and the magnetic field line length we calculate the travel time for the ions. When we examine the distance from the cleft versus the O travel time for individual passes, the slope of the line is consistent with the measured ionospheric convection speed across the polar cap. We conclude that O ions emanating principally from the cleft are transported across the polar cap, and these O ions have access to the ring current and plasma sheet.

  17. Transmission Through Carbon Nanotubes with Polyhedral Caps

    NASA Technical Reports Server (NTRS)

    Anantram, M. P.; Govindan, T. R.

    1999-01-01

    We study electron transport between capped carbon nanotubes and a substrate, and relate this transport to the local density of states in the cap. Our results show that that the transmission probability mimics the behavior of the density of states at all energies except those that correspond to localized states. For a capped carbon nanotube that is not connected to a substrate, the localized states do not couple to the coexisting continuum states. However, close proximity of a substrate causes hybridization between these states. As a result, new transmission paths open from substrate states to nanotube continuum states via the localized states in the cap. We show that the interference between various paths gives rise to transmission antiresonances with the minimum equal to zero at the energy of the localized state. The presence of defects in the tube places close to the cap transforms antiresonances into resonances. Depending on the spatial position of defects, these resonant states are capable of carrying a large current. The results of this paper are of relevance to carbon nanotube based studies on molecular electronics and probe tip applications.

  18. Pluto Insolation and the South Polar Cap

    NASA Astrophysics Data System (ADS)

    Rubincam, D. P.

    2009-05-01

    Pluto's south polar cap is a puzzle. The planet's southern cap may be brighter than the north, even though it was the south pole which faced the Sun on Pluto's recent approach to perihelion. One would think that the brighter pole would be the one which received less insolation: volatiles would be expected to sublimate from the sunny south and condense in the north, enlarging the north polar cap with fresh and bright frost. Thus the north pole should be brighter than the south. However, it may be the other way around, although the evidence is not entirely clear. One suggested explanation of the (possible) paradox is that the south polar cap has, over the last several million years, received less insolation than the north, accumulating a larger supply of volatiles. However, expressing the solar insolation in terms of Pluto's orbital elements clearly shows that both the north and south poles have received nearly the same amount of sunlight over the past several million years. Hence any difference between the polar caps cannot be ascribed to a difference in the amount of long-term insolation received at each pole. Thus any difference between the poles, if there is one, must invoke conditions peculiar to Pluto's climate system, rather than rely on insolation alone.

  19. The use of airborne radar reflectometry to characterize near-surface snow/firn stratigraphy on Devon Ice Cap, Canadian Arctic: A path to identifying refrozen melt layers

    NASA Astrophysics Data System (ADS)

    Rutishauser, A.; Grima, C.; Sharp, M. J.; Blankenship, D. D.; Young, D. A.; Dowdeswell, J. A.

    2015-12-01

    Under present warming conditions, summer surface melt has been observed to intensify and shift towards higher elevations in the accumulation zones of Canadian Arctic ice caps. Consequently, more meltwater percolates into the near surface snow and firn, and refreezes as ice layers. This process can lead to a significant increase in firn densification rates. Knowledge of spatiotemporal variations of the near-surface firn density, especially the distribution of ice layer formation is of great importance when assessing mass change estimates from repeat altimetry measurements. Here, we present an approach for characterizing the near-surface firn stratigraphy and determining the spatial distribution of refrozen melt layers on Devon Ice Cap, using the surface echo from airborne radio-echo sounding (RES) measurements. The RES surface echo is affected by the upper few meters of snow/firn/ice and thus contains information about the near-surface properties. More specifically, the radar surface return is a combination of a coherent (Pc) and a scattering signal component (Pn). Pc is related to the dielectric constant of the probed surface, whereas Pn is related to the near surface roughness. Hence, different near-surface snow/firn properties can be investigated by analyzing the signal components Pc and Pn and their spatial variability. The Radar Statistical Reconnaissance (RSR) methodology [1] allows the extraction of Pc and Pn from the surface radar return, which then can be used to compute near-surface roughness and firn density estimates. We apply the RSR method to RES data collected on Devon Ice Cap and determine Pc and Pn values. We then compare the results to ground based RES measurements and shallow firn cores (~11 m deep) collected along the airborne RES flight lines. This comparison shows that variations in the scattering coefficient Pn correlate to changes in the pattern of near-surface firn stratigraphy revealed by the ground based RES data and firn cores. Based on

  20. Core transfer

    NASA Astrophysics Data System (ADS)

    Good news for all petroleum geoscientists, mining and environmental scientists, university researchers, and the like: Shell Oil Company has deeded its Midland core and sample repository to the Bureau of Economic Geology (BEG) at the University of Texas at Austin. The Midland repository includes more than 1 million linear meters of slab, whole core, and prepared cuttings. Data comprising one of the largest U.S. core collections—the geologic samples from wells drilled in Texas and 39 other states—are now public data and will be incorporated into the existing BEG database. Both Shell and the University of Texas at Austin are affiliated with the American Geological Institute, which assisted in arranging the transfer as part of its goal to establish a National Geoscience Data Repository System at regional centers across the United States.

  1. Holocene Fluctuations of North Ice Cap, a Proxy for Climate Conditions along the Northwestern Margin of the Greenland Ice Sheet

    NASA Astrophysics Data System (ADS)

    Kelly, M. A.; Osterberg, E. C.; Lasher, G. E.; Farnsworth, L. B.; Howley, J. A.; Axford, Y.; Zimmerman, S. R. H.

    2015-12-01

    North Ice Cap (~76.9°N, 68°W, summit elevation 1322 m asl), a small, independent ice cap in northwestern Greenland, is located within ~25 km of the Greenland Ice Sheet margin and Harald Molkte Bræ outlet glacier. We present geochronological, geomorphic and sedimentological data constraining the Holocene extents of North Ice Cap and suggest that its past fluctuations can be used as a proxy for climate conditions along the northwestern margin of the Greenland Ice Sheet. Prior work by Goldthwait (1960) used glacial geomorphology and radiocarbon ages of subfossil plants emerging along shear planes in the ice cap margin to suggest that that North Ice Cap was not present during the early Holocene and nucleated in the middle to late Holocene time, with the onset of colder conditions. Subfossil plants emerging at shear planes in the North Ice Cap margin yield radiocarbon ages of ~4.8-5.9 cal kyr BP (Goldthwait, 1960) and ~AD 1000-1350 (950-600 cal yr BP), indicating times when the ice cap was smaller than at present. In situ subfossil plants exposed by recent ice cap retreat date to ~AD 1500-1840 (450-110 cal yr BP) and indicate small fluctuations of the ice cap margin. 10Be ages of an unweathered, lichen-free drift <100 m from the present North Ice Cap margin range from ~500 to 8000 yrs ago. We suggest that the drift was deposited during the last ~500 yrs and that the older 10Be ages are influenced by 10Be inherited from a prior period of exposure. We also infer ice cap fluctuations using geochemical data from a Holocene-long sediment core from Deltasø, a downstream lake that currently receives meltwater from North Ice Cap. The recent recession of the North Ice Cap margin influenced a catastrophic drainage of a large proglacial lake, Søndre Snesø, that our field team documented in August 2012. To our knowledge, this is the first significant lowering of Søndre Snesø in historical time.

  2. An analytical model of capped turbulent oscillatory bottom boundary layers

    NASA Astrophysics Data System (ADS)

    Shimizu, Kenji

    2010-03-01

    An analytical model of capped turbulent oscillatory bottom boundary layers (BBLs) is proposed using eddy viscosity of a quadratic form. The common definition of friction velocity based on maximum bottom shear stress is found unsatisfactory for BBLs under rotating flows, and a possible extension based on turbulent kinetic energy balance is proposed. The model solutions show that the flow may slip at the top of the boundary layer due to capping by the water surface or stratification, reducing the bottom shear stress, and that the Earth's rotation induces current and bottom shear stress components perpendicular to the interior flow with a phase lag (or lead). Comparisons with field and numerical experiments indicate that the model predicts the essential characteristics of the velocity profiles, although the agreement is rather qualitative due to assumptions of quadratic eddy viscosity with time-independent friction velocity and a well-mixed boundary layer. On the other hand, the predicted linear friction coefficients, phase lead, and veering angle at the bottom agreed with available data with an error of 3%-10%, 5°-10°, and 5°-10°, respectively. As an application of the model, the friction coefficients are used to calculate e-folding decay distances of progressive internal waves with a semidiurnal frequency.

  3. Comparison of Mars Northern Cap Edge Advance and Recession Rates over the Last 6 Mars Years

    NASA Astrophysics Data System (ADS)

    Titus, T. N.; Cushing, G. E.; Langevin, Y.; Brown, A. J.; Themis Science Team; CRISM Science Team

    2011-12-01

    The most observable parameter that describes the Mars polar seasonal caps is their size, which has been measured since the days of Herschel. The advance and retreat of the polar cap from year to year may exhibit many clues to help elucidate little understood physical processes. For example, summertime heat storage in the regolith could delay the onset of seasonal CO2 cap formation. The evolution of the seasonal cap could also be directly affected by the thermal inertia of the near-surface regolith and place constraints on the depth of the ice table. Parameterizations of the seasonal cap edges provide useful constraints on atmospheric GCMs and mesoscale models. Longitudinally resolving the cap edges as they advance and retreat constrains the times when zonal means are appropriate and when longitudinal asymmetries make zonal means invalid. These same kinds of parameterizations can also be used when modeling other data that have low spatial resolutions, such as Gamma Ray Spectrometer (GRS )and Neutron Spectrometer (NS) data. By knowing where the cap edge should be, coarse spatial data can correct for subpixel mixing caused by large point-spread functions including both frosted and frost-free areas. The northern cap exhibits a near symmetric retreat, which has been well characterized at visible wavelengths by both telescopic and spacecraft observations. However, the advance of the cap has not been well characterized until the 21st century. Kieffer and Titus (2001) have used zonal means to observe surface temperature and visible bolometric albedo variations with season using MGS/TES. The TES thermal observations show an almost perfectly symmetrical advance; i.e., condensation at consistent latitude across all longitudes, with the most northern edge of the seasonal cap occurring between longitudes 245°E to 265°E and the most southern edge of the seasonal cap occurring between 280°E and 30°E. The advance of the northern cap typically leads the advance of the edge of

  4. Effect of environment on the preparation of CdSe quantum dots capped with mercaptoacetic acid.

    PubMed

    Wageh, S; Higazy, Anwer A; Al-Ghamdi, Ahmed A; Hassouna, Ahmed S

    2014-08-01

    We report a preparation of CdSe quantum dots in the presence of capping molecules under ambient air and argon atmospheres. The growth of the quantum dots with applying an equimolar ratio of precursor of Cd2+ and Se2- in the presence of a high percentage of the mercaptoacetic acid as capping molecules is studied. Quantum dots are characterized via EDX, transmission electron microscopy, X-ray diffraction, thermogravimetric analysis (TGA), UV-Vis optical absorption, Raman and infrared spectroscopy. Combination of EDX and Raman spectroscopy showed a graded diffusion of sulfur on the surface of CdSe quantum dots for the sample prepared under argon atmosphere, while the sample prepared under ambient air atmosphere the sulfur isn't diffused into the CdSe core. In addition, the sample prepared under air revealed a formation of oxides on the surface of the quantum dots. On the other hand, we have studied the nature of capping and how the surface of the quantum dots core is terminated for the prepared samples. In addition, we have studied the acoustic and optical phonons of the quantum dots cores.

  5. Geological and geophysical properties of cap rock in a natural CO2 occurrence, Mihályi-Répcelak area, Western Hungary

    NASA Astrophysics Data System (ADS)

    Király, Csilla; Szamosfalvi, Ágnes; Sendula, Eszter; Páles, Mariann; Kovács, István; Kónya, Péter; Falus, György; Szabó, Csaba

    2015-04-01

    The physical and geochemical consistency of the cap rock is primarily important for safe geological storage of CO2.. As a consequence of CO2 injection reactions took place between the minerals of the reservoir, the cap rock and CO2 saturated pore water. These reactions may change the mineral composition and petrophysical properties of the storage reservoir as well as the cap rock that provides the only physical barrier that retains carbon dioxide in the target reservoir formation. Study of the natural CO2 occurrences delivers information to understand which properties of a cap rock provide the sustainable closure and retainment. Knowledge of the long term effect of CO2 on the behavior of the cap rock is an important input in the selection procedure of a potential CO2 injection site. Yet, very few data exist on geochemical properties and reactivity of the cap rocks. During normal commercial operations the reservoir is typically cored, but not the cap rock. This study may enhance our knowledge about possible mineralogical reactions, which can occur in clayey-aleuritic cap rocks. The Mihályi-Répcelak natural CO2 occurrence is believed to be leakage safe. There is no known seepage on the surface. It is suggested that the aleuritic clay rich cap rock occurring at the natural reservoir can stop CO2 migration into other reservoirs or to the surface. The most important characteristics of cap rocks that they have low permeability (<0.1 mD) and porosity (eff.por. = 4%) and high clayeyness (approx. 80%). However, we demonstrate that in addition to these parameters the geochemical properties of cap rock is also important. In order to characterize the natural CO2 occurrence, we applied the following analysis, like XRD, FTIR, SEM. The petrophysical properties are determined from the interpretation of geophysical well-logs and grain size distribution. The most important result of this study that adequate petrophysical properties do not completely define the suitability of a cap

  6. Intermediate filaments in. cap alpha. -keratins

    SciTech Connect

    Fraser, R.D.B.; MacRae, T.P.; Parry, D.A.D.; Suzuki, E.

    1986-03-01

    Previous x-ray diffraction studies on the ..cap alpha..-keratins of hair and wool have revealed that the intermediate filaments (IF) have a helical structure rendered imperfect by a precisely defined dislocation. It has also been possible to deduce a surface lattice for the IF and to determine the number of IF molecules associated with each lattice point. In this work this information is combined with data on the ionic interactions between the coiled-coil rope segments of the IF molecules to provide a plausible model for the pattern of interactions that stabilize the framework of the IF in the hard ..cap alpha..-keratins. Similar interaction studies of the proteins from the IF in the so-called soft ..cap alpha..-keratin from the stratum corneum layer of the skin suggest that they are likely to have an essentially similar pattern.

  7. Compact bearing cap for overhead camshaft

    SciTech Connect

    Bakker, E.A.M.

    1992-06-09

    This patent describes an internal combustion engine of the type having a cylinder head assembly with at least one rotatable camshaft with end journal portions mounted in semi-cylindrical bearings of the cylinder head, an improved camshaft retention arrangement for the end portion. It comprises a bearing cap with a semi-cylindrical portion at an opposite side of the camshaft journal as the cylinder head bearing portion, first fastener means extending through the the portion into the cylinder head to secure the bearing cap to the cylinder head; the semi-cylindrical portion of the bearing cap extending from the side portion about the camshaft journal and terminating just short of a second side of the camshaft so that an area of the cylinder head immediately adjacent the second side of the camshaft is available for placement of a second fastener means for securing the cylinder head to the engine.

  8. Biocompatibility of a new pulp capping cement

    PubMed Central

    Poggio, Claudio; Ceci, Matteo; Beltrami, Riccardo; Dagna, Alberto; Colombo, Marco; Chiesa, Marco

    2014-01-01

    Summary Aim The aim of the present study was to evaluate the biocompatibility of a new pulp capping material (Biodentine, Septodont) compared with reference pulp capping materials: Dycal (Dentsply), ProRoot MTA (Dentsply) and MTA-Angelus (Angelus) by using murine odontoblast cell line and Alamar blue and MTT cytotoxicity tests. Methods The citocompatibility of murine odontoblasts cells (MDPC-23) were evaluated at different times using a 24 Transwell culture plate by Alamar blue test and MTT assay. Results The results were significantly different among the pulp capping materials tested. Biocompatibility was significant different among materials with different composition. Conclusions Biodentine and MTA-based products show lower cytotoxicity varying from calcium hydroxide-based material which present higher citotoxicity. PMID:25002921

  9. Deformation of Polar Cap Patches During Substorms

    NASA Astrophysics Data System (ADS)

    Zou, S.; Ridley, A. J.; Nicolls, M. J.; Coster, A. J.; Thomas, E. G.; Ruohoniemi, J. M.; Hampton, D.

    2015-12-01

    Polar cap patches refer to the islands of high F-region plasma density within the polar cap. Their formation on the dayside and deformation on the nightside are not well understood. The F-layer ionosphere density is strongly influenced by electric field, thermospheric wind as well as soft particle precipitation. This study combines observations from multiple instruments, including Poker Flat incoherent scatter radar, GPS TEC and optical instruments, as well as the Global Ionosphere and Thermosphere Model (GITM), to investigate the effects of highly structured electric fields and winds on the deformation of polar cap patches during substorms. We will also discuss variations of the auroral emissions associated with the patch evolution.

  10. Electronic States in Capped Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Yaguchi, Tatsuya; Ando, Tsuneya

    2001-05-01

    Scattering of an electron wave at various caps closing an armchair nanotube is studied. The reflection coefficients can be understood as an effective shift in boundary position and phase shift at the boundary. The phase shift is approximately given by π for states with parity + and 0 for states with parity -, respectively. The effective position is approximated by (1/4)P, where P is the height of an equilateral triangle having a base line determined by neighboring five-membered rings located at the boundary between the tube and the cap. The electronic structure of a finite-length armchair nanotube closed by a cap can be calculated with the use of the phase shifts.

  11. Lymphocyte activation and capping of hormone receptors.

    PubMed

    Bourguignon, L Y; Jy, W; Majercik, M H; Bourguignon, G J

    1988-06-01

    In this study both a ligand-dependent treatment [concanavalin A (Con A)] and a ligand-independent treatment [high-voltage pulsed galvanic stimulation (HVPGS)] have been used to initiate lymphocyte activation via a transmembrane signaling process. Our results show that both treatments cause the exposure of two different hormone [insulin and interleukin-2 (IL-2)] receptors within the first 5 min of stimulation. When either insulin or IL-2 is present in the culture medium, the stimulated lymphocytes undergo the following responses: (1) increased free intracellular Ca2+ activity; (2) aggregation of insulin or IL-2 receptors into patch/cap structures; (3) tyrosine-kinase-specific phosphorylation of a 32-kd membrane protein; and finally (4) induction of DNA synthesis. Further analysis indicates that hormone receptor capping is inhibited by (1) cytochalasin D, suggesting the involvement of microfilaments; (2) sodium azide, indicating a requirement for ATP production; and (3) W-5, W-7, and W-12 drugs, implying a need for Ca2+/calmodulin activity. Treatment with these metabolic or cytoskeletal inhibitors also prevents both the tyrosine-kinase-specific protein phosphorylation and DNA synthesis which normally follow hormone receptor capping. Double immunofluorescence staining shows that actomyosin, Ca2+/calmodulin, and myosin light-chain kinase are all closely associated with the insulin and IL-2 receptor cap structures. These findings strongly suggest that an actomyosin-mediated contractile system (regulated by Ca2+, calmodulin, and myosin light-chain kinase in an energy-dependent manner) is required not only for the collection of insulin and IL-2 receptors into patch and cap structures but also for the subsequent activation of tyrosine kinase and the initiation of DNA synthesis. We, therefore, propose that the exposure and subsequent patching/capping of at least one hormone receptor are required for the activation of mouse splenic T-lymphocytes.

  12. Martian north polar cap summer water cycle

    NASA Astrophysics Data System (ADS)

    Brown, Adrian J.; Calvin, Wendy M.; Becerra, Patricio; Byrne, Shane

    2016-10-01

    A key outstanding question in Martian science is "are the polar caps gaining or losing mass and what are the implications for past, current and future climate?" To address this question, we use observations from the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) of the north polar cap during late summer for multiple Martian years, to monitor the summertime water cycle in order to place quantitative limits on the amount of water ice deposited and sublimed in late summer. We establish here for the first time the summer cycle of water ice absorption band signatures on the north polar cap. We show that in a key region in the interior of the north polar cap, the absorption band depths grow until Ls = 120, when they begin to shrink, until they are obscured at the end of summer by the north polar hood. This behavior is transferable over the entire north polar cap, where in late summer regions 'flip' from being net sublimating into net condensation mode. This transition or 'mode flip' happens earlier for regions closer to the pole, and later for regions close to the periphery of the cap. The observations and calculations presented herein estimate that on average a water ice layer ∼70 microns thick is deposited during the Ls = 135-164 period. This is far larger than the results of deposition on the south pole during summer, where an average layer 0.6-6 microns deep has been estimated by Brown et al. (2014) Earth Planet. Sci. Lett., 406, 102-109.

  13. Valve Cap For An Electric Storage Cell

    DOEpatents

    Verhoog, Roelof; Genton, Alain

    2000-04-18

    The valve cap for an electric storage cell includes a central annular valve seat (23) and a membrane (5) fixed by its peripheral edge and urged against the seat by a piston (10) bearing thereagainst by means of a spring (12), the rear end of said spring (12) bearing on the endwall (8) of a chamber (20) formed in the cap and containing the piston (10) and the spring. A vent (19) puts the chamber (20) into communication with the atmosphere. A central orifice (26, 28) through the piston (10) and the membrane (5), enables gas from within the cell to escape via the top vent (19) when the valve opens.

  14. Evaluation of MerCAP for Power Plant Mercury Control

    SciTech Connect

    Carl Richardson

    2008-09-30

    {trademark} performance. At Site 2, a pilot-scale array was installed in a horizontal reactor chamber designed to treat approximately 2800 acfm of flue gas obtained from downstream of the plant's flue gas desulfurization (FGD) system. The initial MerCAP{trademark} array was installed at Plant Yates in January 2004, operating continuously for several weeks before a catastrophic system failure resulting from a failed flue gas fan. A second MerCAP{trademark} array was installed in July 2006 and operated for one month before being shut down for a reasons pertaining to system performance and host site scheduling. A longer-term continuous-operation test was then conducted during the summer and fall of 2007. Tests were conducted to evaluate the impacts of flue gas flow rate, sorbent space velocity, and sorbent rinsing frequency on mercury removal performance. Detailed characterization of treated sorbent plates was carried out in an attempt to understand the nature of reactions leading to excessive corrosion of the substrate surfaces.

  15. Lead Pencils

    NASA Technical Reports Server (NTRS)

    Gray, L. B.

    1971-01-01

    A study, undertaken to determine the lead content of paint on various pencils in the Goddard supply system, is reported. The survey found that lead content varied from .04 mg per pencil for carmine colored pencils to approximately 43 mg per pencil for yellow colored pencils. Results also show that yellow pencils had higher lead content than other colors analyzed. More detailed results are given in tabular form.

  16. Distinct Features of Cap Binding by eIF4E1b Proteins

    PubMed Central

    Kubacka, Dorota; Miguel, Ricardo Núñez; Minshall, Nicola; Darzynkiewicz, Edward; Standart, Nancy; Zuberek, Joanna

    2015-01-01

    eIF4E1b, closely related to the canonical translation initiation factor 4E (eIF4E1a), cap-binding protein is highly expressed in mouse, Xenopus and zebrafish oocytes. We have previously characterized eIF4E1b as a component of the CPEB mRNP translation repressor complex along with the eIF4E-binding protein 4E-Transporter, the Xp54/DDX6 RNA helicase and additional RNA-binding proteins. eIF4E1b exhibited only very weak interactions with m7GTP-Sepharose and, rather than binding eIF4G, interacted with 4E-T. Here we undertook a detailed examination of both Xenopus and human eIF4E1b interactions with cap analogues using fluorescence titration and homology modeling. The predicted structure of eIF4E1b maintains the α + β fold characteristic of eIF4E proteins and its cap-binding pocket is similarly arranged by critical amino acids: Trp56, Trp102, Glu103, Trp166, Arg112, Arg157 and Lys162 and residues of the C-terminal loop. However, we demonstrate that eIF4E1b is 3-fold less well able to bind the cap than eIF4E1a, both proteins being highly stimulated by methylation at N7 of guanine. Moreover, eIF4E1b proteins are distinguishable from eIF4E1a by a set of conserved amino acid substitutions, several of which are located near to cap-binding residues. Indeed, eIF4E1b possesses several distinct features, namely, enhancement of cap binding by a benzyl group at N7 position of guanine, a reduced response to increasing length of the phosphate chain and increased binding to a cap separated by a linker from Sepharose, suggesting differences in the arrangement of the protein's core. In agreement, mutagenesis of the amino acids differentiating eIF4E1b from eIF4E1a reduces cap binding by eIF4E1a 2-fold, demonstrating their role in modulating cap binding. PMID:25463438

  17. Distinct features of cap binding by eIF4E1b proteins.

    PubMed

    Kubacka, Dorota; Miguel, Ricardo Núñez; Minshall, Nicola; Darzynkiewicz, Edward; Standart, Nancy; Zuberek, Joanna

    2015-01-30

    eIF4E1b, closely related to the canonical translation initiation factor 4E (eIF4E1a), cap-binding protein is highly expressed in mouse, Xenopus and zebrafish oocytes. We have previously characterized eIF4E1b as a component of the CPEB mRNP translation repressor complex along with the eIF4E-binding protein 4E-Transporter, the Xp54/DDX6 RNA helicase and additional RNA-binding proteins. eIF4E1b exhibited only very weak interactions with m(7)GTP-Sepharose and, rather than binding eIF4G, interacted with 4E-T. Here we undertook a detailed examination of both Xenopus and human eIF4E1b interactions with cap analogues using fluorescence titration and homology modeling. The predicted structure of eIF4E1b maintains the α+β fold characteristic of eIF4E proteins and its cap-binding pocket is similarly arranged by critical amino acids: Trp56, Trp102, Glu103, Trp166, Arg112, Arg157 and Lys162 and residues of the C-terminal loop. However, we demonstrate that eIF4E1b is 3-fold less well able to bind the cap than eIF4E1a, both proteins being highly stimulated by methylation at N(7) of guanine. Moreover, eIF4E1b proteins are distinguishable from eIF4E1a by a set of conserved amino acid substitutions, several of which are located near to cap-binding residues. Indeed, eIF4E1b possesses several distinct features, namely, enhancement of cap binding by a benzyl group at N(7) position of guanine, a reduced response to increasing length of the phosphate chain and increased binding to a cap separated by a linker from Sepharose, suggesting differences in the arrangement of the protein's core. In agreement, mutagenesis of the amino acids differentiating eIF4E1b from eIF4E1a reduces cap binding by eIF4E1a 2-fold, demonstrating their role in modulating cap binding. Copyright © 2014. Published by Elsevier Ltd.

  18. Truss-core corrugation for compressive loads

    NASA Technical Reports Server (NTRS)

    Davis, Randall C. (Inventor); Jackson, Robert (Inventor)

    1988-01-01

    A corrugated panel structure for supporting compressive loads is described which includes curved cap strips separated by truss-core web segments. The truss-core web segments are formed from first and second flat panels with a corrugated filler in between them. The corrugated filler extends in the direction of the compressive load. As a result, all components of the panel structure have a compressive load carrying capability resulting in a high strength-to-weight ratio when the compressive load is limiting. Application to rocket and aircraft structures is suggested.

  19. Truss-core corrugation for compressive loads

    NASA Astrophysics Data System (ADS)

    Davis, Randall C.; Jackson, Robert

    1988-09-01

    A corrugated panel structure for supporting compressive loads is described which includes curved cap strips separated by truss-core web segments. The truss-core web segments are formed from first and second flat panels with a corrugated filler in between them. The corrugated filler extends in the direction of the compressive load. As a result, all components of the panel structure have a compressive load carrying capability resulting in a high strength-to-weight ratio when the compressive load is limiting. Application to rocket and aircraft structures is suggested.

  20. Core layering

    NASA Astrophysics Data System (ADS)

    Jacobson, S. A.; Rubie, D. C.; Hernlund, J. W.; Morbidelli, A.

    2015-12-01

    We have created a planetary accretion and differentiation model that self-consistently builds and evolves Earth's core. From this model, we show that the core grows stably stratified as the result of rising metal-silicate equilibration temperatures and pressures, which increases the concentrations of light element impurities into each newer core addition. This stable stratification would naturally resist convection and frustrate the onset of a geodynamo, however, late giant impacts could mechanically mix the distinct accreted core layers creating large homogenous regions. Within these regions, a geodynamo may operate. From this model, we interpret the difference between the planetary magnetic fields of Earth and Venus as a difference in giant impact histories. Our planetary accretion model is a numerical N-body integration of the Grand Tack scenario [1]—the most successful terrestrial planet formation model to date [2,3]. Then, we take the accretion histories of Earth-like and Venus-like planets from this model and post-process the growth of each terrestrial planet according to a well-tested planetary differentiation model [4,5]. This model fits Earth's mantle by modifying the oxygen content of the pre-cursor planetesimals and embryos as well as the conditions of metal-silicate equilibration. Other non-volatile major, minor and trace elements included in the model are assumed to be in CI chondrite proportions. The results from this model across many simulated terrestrial planet growth histories are robust. If the kinetic energy delivered by larger impacts is neglected, the core of each planet grows with a strong stable stratification that would significantly impede convection. However, if giant impact mixing is very efficient or if the impact history delivers large impacts late, than the stable stratification can be removed. [1] Walsh et al. Nature 475 (2011) [2] O'Brien et al. Icarus 223 (2014) [3] Jacobson & Morbidelli PTRSA 372 (2014) [4] Rubie et al. EPSL 301

  1. Possible Composition of Martian Polar Caps and Controls on Ice-Cap Behavior

    NASA Astrophysics Data System (ADS)

    Kargel, J. S.

    1998-01-01

    David Fisher asked "if martian polar caps flow." Are martian polar caps akin to Earth's polar glacial ice sheets, or are they immobile? Though certain dynamical differences are obvious, it is unknown whether similarities in ice tectonics may also exist. The question bears not only on modem martian polar processes, but perhaps on hypothesized glacial processes elsewhere on Mars in the geologic past. The rheological properties and tectonics of martian polar caps also pertain to the possibility that liquids may have existed beneath the polar caps in the past, or even now, and to prospects for life in possible lakes beneath the ice caps. The cold martian polar surface temperatures and the lower martian gravity suggest a reduced propensity of martian polar ice deposits to deform under their own weight. The greater accumulation timescales of the martian polar caps compared to Earth's also mean that more time has been available for accumulated deformation, possibly offsetting the effects of colder temperatures and lower gravity on Mars. Further complicating our understanding is that the martian polar caps may not be made purely of ordinary water ice - CO2 is another possible major constituent; the rheological and melting behavior may be very different from what we are accustomed to dealing with on Earth.

  2. Purification and characterization of the glycoprotein hormone. cap alpha. -subunit-like material secreted by HeLa cells

    SciTech Connect

    Cox, G.S.; Rimerman, R.A.

    1988-08-23

    The protein secreted by HeLa cells that cross-reacts with antiserum developed against the ..cap alpha..-subunit of human chorionic gonadotropin (hCG) has been purified approximately 30,000-fold from concentrated culture medium by organic solvent fractionation followed by ion exchange, gel filtration, and lectin affinity chromatography. The final preparation had a specific activity (by RIA) of 6.8 x 10/sup 5/ ng of ..cap alpha../mg of protein and appeared homogeneous by electrophoresis on reducing/denaturing polyacrylamide gels (SDS-PAGE). Amino acid analysis indicated that HeLa-..cap alpha.. had a composition very similar to that of the urinary hCG ..cap alpha..-subunit. However, comparison of hCG-..cap alpha.. and HeLa-..cap alpha.. demonstrated that the tumor-associated subunit was not identical with its normal counterpart. The purified tumor protein had an apparent molecular weight greater than that of the urinary ..cap alpha..-subunit when analyzed by SDS-PAGE, and this difference was even greater when a partially purified preparation was examined by an immunoblot technique (Western). Isoelectric focusing of the HeLa and hCG subunits demonstrated that the tumor protein had a lower pI. Immunoprecipitation and electrophoresis of ..cap alpha..-subunit from HeLa cultures labeled with (/sup 3/H)fucose indicated that the tumor subunit was fucosylated, whereas analysis of hCG-..cap alpha.. hydrosylates by HPLC confirmed previous reports that the placental subunit does not contain fucose. The results indicate that, regardless of whether or not a single ..cap alpha..-subunit gene is being expressed in both normal and neoplastic tissues, posttranslational modifications lead to a highly altered subunit in the tumor. The differences observed may be useful in diagnosing neoplastic vs hyperplastic conditions and may lend insight into the mechanism of ectopic hormone production by tumors.

  3. Preparation, characterization and dielectric studies on carbonyl iron/cellulose acetate hydrogen phthalate core/shell nanoparticles for drug delivery applications.

    PubMed

    Reshmi, G; Mohan Kumar, P; Malathi, M

    2009-01-05

    A method to prepare composite colloidal nanoparticles, consisting of a magnetic core (carbonyl iron) and a biodegradable polymeric shell (cellulose acetate hydrogen phthalate) was described and also particle size was characterized by Optical Microscope and Scanning Electron Microscopy. Dielectric properties of Cellulose Acetate Hydrogen Phthalate (CAP) and carbonyl iron/CAP (core/shell) tablets were studied in the frequency range of 70 Hz-400 kHz at 300 K using LCR meter and compared the dielectric parameters of core/shell and ordinary phase of CAP tablets. From the dielectric results, the importance of core/shell nanoparticles in controlled drug delivery was discussed.

  4. Some core contested concepts.

    PubMed

    Chomsky, Noam

    2015-02-01

    Core concepts of language are highly contested. In some cases this is legitimate: real empirical and conceptual issues arise. In other cases, it seems that controversies are based on misunderstanding. A number of crucial cases are reviewed, and an approach to language is outlined that appears to have strong conceptual and empirical motivation, and to lead to conclusions about a number of significant issues that differ from some conventional beliefs.

  5. Cap-assisted colonoscopy and detection of Adenomatous Polyps (CAP) study: a randomized trial.

    PubMed

    Pohl, Heiko; Bensen, Steve P; Toor, Arifa; Gordon, Stuart R; Levy, L Campbell; Berk, Brian; Anderson, Peter B; Anderson, Joseph C; Rothstein, Richard I; MacKenzie, Todd A; Robertson, Douglas J

    2015-10-01

    Cap-assisted colonoscopy has improved adenoma detection in some but not other studies. Most previous studies have been limited by small sample sizes and few participating endoscopists. The aim of the current study was to evaluate whether cap-assisted colonoscopy improves adenoma detection in a two-center, multi-endoscopist, randomized trial. Consecutive patients who presented for an elective colonoscopy were randomized to cap-assisted colonoscopy (4-mm cap) or standard colonoscopy performed by one of 10 experienced endoscopists. Primary outcome measures were mean number of adenomas per patient and adenoma detection rate (ADR). Secondary outcomes included procedural measures and endoscopist variation; a logistic regression model was employed to examine predictors of increased detection with cap use. A total of 1113 patients (64 % male, mean age 62 years) were randomized to cap-assisted (n = 561) or standard (n = 552) colonoscopy. The mean number of adenomas detected per patient in the cap-assisted and standard groups was similar (0.89 vs. 0.82; P = 0.432), as was the ADR (42 % vs. 40 %; P = 0.452). Cap-assisted colonoscopy achieved a faster cecal intubation time (4.9 vs. 5.8 minutes; P < 0.001), a similar cecal intubation rate (99 % vs. 98 %; P = 0.326), and a higher terminal ileum intubation rate (93 % vs. 89 %; P < 0.028). Cap-assisted colonoscopy resulted in a 20 % increase in ADR for some endoscopists and in a 15 % decrease for others. Individual preference for the cap was an independent predictor of increased adenoma detection in adjusted analysis (P < 0.001), whereas baseline low adenoma detection was not. Although the efficiency of cecal and terminal ileum intubation was slightly improved by cap-assisted colonoscopy, adenoma detection was not. Cap-assisted colonoscopy may be beneficial for selected endoscopists. clinicalTrials.gov (NCT01935180). © Georg Thieme Verlag KG Stuttgart · New York.

  6. Leading Democratically

    ERIC Educational Resources Information Center

    Brookfield, Stephen

    2010-01-01

    Democracy is the most venerated of American ideas, the one for which wars are fought and people die. So most people would probably agree that leaders should be able to lead well in a democratic society. Yet, genuinely democratic leadership is a relative rarity. Leading democratically means viewing leadership as a function or process, rather than…

  7. Recombination and Population Mosaic of a Multifunctional Viral Gene, Adeno-Associated Virus cap

    PubMed Central

    Takeuchi, Yasuhiro; Myers, Richard; Danos, Olivier

    2008-01-01

    Homologous recombination is a dominant force in evolution and results in genetic mosaics. To detect evidence of recombination events and assess the biological significance of genetic mosaics, genome sequences for various viral populations of reasonably large size are now available in the GenBank. We studied a multi-functional viral gene, the adeno-associated virus (AAV) cap gene, which codes for three capsid proteins, VP1, VP2 and VP3. VP1-3 share a common C-terminal domain corresponding to VP3, which forms the viral core structure, while the VP1 unique N-terminal part contains an enzymatic domain with phospholipase A2 activity. Our recombinant detection program (RecI) revealed five novel recombination events, four of which have their cross-over points in the N-terminal, VP1 and VP2 unique region. Comparison of phylogenetic trees for different cap gene regions confirmed discordant phylogenies for the recombinant sequences. Furthermore, differences in the phylogenetic tree structures for the VP1 unique (VP1u) region and the rest of cap highlighted the mosaic nature of cap gene in the AAV population: two dominant forms of VP1u sequences were identified and these forms are linked to diverse sequences in the rest of cap gene. This observation together with the finding of frequent recombination in the VP1 and 2 unique regions suggests that this region is a recombination hot spot. Recombination events in this region preserve protein blocks of distinctive functions and contribute to convergence in VP1u and divergence of the rest of cap. Additionally the possible biological significance of two dominant VP1u forms is inferred. PMID:18286191

  8. Rapidly Melting Ice Caps of Northern Baffin Island: Insights From Cosmogenic and Conventional Radiocarbon Dating

    NASA Astrophysics Data System (ADS)

    Anderson, R. K.; Miller, G. H.; Briner, J. P.; Lifton, N.; Devogel, S. B.

    2006-12-01

    The interior plateau of northern Baffin Island in the eastern Canadian Arctic is home to several small (< 50 km2) ice caps whose melt has been well recorded since 1949. Modern equilibrium line altitude (ELA) is well above all existing ice and a continuation of current climatic conditions will lead to the disappearance of all ice on the plateau in the future. Between 2000 and 2005, approximately 1 km2 of ice was lost per year, equivalent to ~1.3% of the total ice cover on the plateau. To put this current melt into a larger picture of ice-cap history on the plateau since deglaciation 6 ka, several techniques have been used in concert. The recent extent of the ice caps during the Little Ice Age can be estimated from the preservation of lichen trimlines across much of the plateau. These trimlines represent previous multi-year snow or ice cover and their aerial extent can be measured via satellite imagery. Based on these measurements, modern ice caps represent only ~3% of ice-cap extent during the Little Ice Age. Radiocarbon dating of moss, preserved beneath the ice caps due to their cold-based nature, suggests a sudden expansion of ice cover around 520 calendar years before present (cal BP), indicated by a mode of 7 dates of approximately this age. This coincides with a pulse of global volcanic activity; predicted cooling from increased aerosol loading may have triggered rapid ice-cap growth. However, dead moss emerging at three sites is more than 1000 years old, with a maximum age of 1326±15 cal BP, indicating that portions of the remaining ice caps have remained intact from more than 1000 years Further constraints on ice cap size are provided by 14C cosmogenic exposure dating. 14C concentrations in rocks at the modern ice margin are too low to be the result of continuous exposure since deglaciation followed by shielding for 500-1000 years by ice cover. Exposure history modeling indicates at least one additional prior period of ice cover of approximately 1000 years

  9. Possible contemporary evaporites formation at the Martian Northern Polar Cap

    NASA Astrophysics Data System (ADS)

    Losiak, Anna; Czechowski, Leszek

    Evaporitic minerals are abundant on the surface of Mars (e.g., Wentworth et al. 2005, Velbel 2012, Clark and Van Hart 1981, Wang et al. 2006, Kuzmin et al. 2009), especially within the Circumpolar Dune Field and on the Northern Ice Cap itself (e.g., Langevin et al., 2005, Roach et al. 2007, Horgan et al. 2009, Masse et al. 2010, 2012). Most of their proposed formation mechanisms require significant amounts of liquid water and are thus not possible under current Martian conditions (Arvidson et al. 2006, Andrews-Hanna et al. 2007, Fishbaugh et al. 2007, Szynkiewicz et al. 2010). Some authors have considered the potential role of ice and ice- or snowmelt-related alteration in the weathering of Martian materials (e.g., Catling et al. 2006, Zolotov and Mironenko 2007, Niles and Michalski 2009, Masse et al. 2010). However, none of those studies discussed details of the process leading to the formation of the evaporites or the timing of the processes. The aim of this paper is to model numerically if the current radiant heating is sufficient to melt a thin layer of ice surrounding a single dust grain exposed within the south facing side of the Martian North Polar Cap trench. The results of our initial study suggest that for dust grains with basaltic properties and ice with low values of coefficient of heat conduction, and solar constant = 492 W/m2 liquid water may exist below a dust grain for up to 4 hours a sol. This suggest that contemporary evaporites formation on Martian Polar Cap is possible.

  10. An RNA cap (nucleoside-2'-O-)-methyltransferase in the flavivirus RNA polymerase NS5: crystal structure and functional characterization.

    PubMed

    Egloff, Marie-Pierre; Benarroch, Delphine; Selisko, Barbara; Romette, Jean-Louis; Canard, Bruno

    2002-06-03

    Viruses represent an attractive system with which to study the molecular basis of mRNA capping and its relation to the RNA transcription machinery. The RNA-dependent RNA polymerase NS5 of flaviviruses presents a characteristic motif of S-adenosyl-L-methionine-dependent methyltransferases at its N-terminus, and polymerase motifs at its C-terminus. The crystal structure of an N-terminal fragment of Dengue virus type 2 NS5 is reported at 2.4 A resolution. We show that this NS5 domain includes a typical methyltransferase core and exhibits a (nucleoside-2'-O-)-methyltransferase activity on capped RNA. The structure of a ternary complex comprising S-adenosyl-L-homocysteine and a guanosine triphosphate (GTP) analogue shows that 54 amino acids N-terminal to the core provide a novel GTP-binding site that selects guanine using a previously unreported mechanism. Binding studies using GTP- and RNA cap-analogues, as well as the spatial arrangement of the methyltransferase active site relative to the GTP-binding site, suggest that the latter is a specific cap-binding site. As RNA capping is an essential viral function, these results provide a structural basis for the rational design of drugs against the emerging flaviviruses.

  11. Survey of Enabling Technologies for CAPS

    NASA Technical Reports Server (NTRS)

    Antol, Jeffrey; Mazanek, Daniel D.; Koons, Robert H.

    2005-01-01

    The enabling technologies required for the development of a viable Comet/Asteroid Protection System (CAPS) can be divided into two principal areas: detection and deflection/orbit modification. With the proper funding levels, many of the technologies needed to support a CAPS architecture could be achievable within the next 15 to 20 years. In fact, many advanced detection technologies are currently in development for future in-space telescope systems such as the James Webb Space Telescope (JWST), formerly known as the Next Generation Space Telescope. It is anticipated that many of the JWST technologies would be available for application for CAPS detection concepts. Deflection/orbit modification technologies are also currently being studied as part of advanced power and propulsion research. However, many of these technologies, such as extremely high-output power systems, advanced propulsion, heat rejection, and directed energy systems, would likely be farther term in availability than many of the detection technologies. Discussed subsequently is a preliminary examination of the main technologies that have been identified as being essential to providing the element functionality defined during the CAPS conceptual study. The detailed requirements for many of the technology areas are still unknown, and many additional technologies will be identified as future in-depth studies are conducted in this area.

  12. Mars South Polar Cap "Fingerprint" Terrain

    NASA Image and Video Library

    2000-04-24

    This picture is illuminated by sunlight from the upper left. Some portions of the martian south polar residual cap have long, somewhat curved troughs instead of circular pits. These appear to form in a layer of material that may be different than that in which "swiss cheese" circles and pits form, and none of these features has any analog in the north polar cap or elsewhere on Mars. This picture shows the "fingerprint" terrain as a series of long, narrow depressions considered to have formed by collapse and widening by sublimation of ice. Unlike the north polar cap, the south polar region stays cold enough in summer to retain frozen carbon dioxide. Viking Orbiter observations during the late 1970s showed that very little water vapor comes off the south polar cap during summer, indicating that any frozen water that might be there remains solid throughout the year. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image was obtained in early southern spring on August 4, 1999. It shows an area 3 x 5 kilometers (1.9 x 3.1 miles) at a resolution of about 7.3 meters (24 ft) per pixel. Located near 86.0°S, 53.9°W. http://photojournal.jpl.nasa.gov/catalog/PIA02373

  13. Science CAP: Curriculum Assistance Program. [Multimedia.

    ERIC Educational Resources Information Center

    DEMCO, Inc., Madison, WI.

    Science Curriculum Assistance Program (Science CAP(TM)) is a multimedia package developed to create a model for preserving classroom science activities that can be shared and customized by teachers. This program is designed to assist teachers in preparing classroom science activities for grades five through eight, and to foster an environment of…

  14. Capping blowouts from Iran's 8-year war

    SciTech Connect

    Sayers, B. )

    1991-07-01

    Control well blown up by the Iraqi military were a 2 1/2 year legacy left the National Iranian Oil Co. at the end of this long conflict. This final installment of a 2-part series describes capping of the largest wind oil well.

  15. Shrinking ice caps in the spotlight.

    PubMed

    Gross, Michael

    2014-10-06

    From the disappearing sea ice of the Arctic to the thriving microbial communities in subglacial lakes of Antarctica, the Earth's ice caps have often made the news in recent months and years, and polar science has emerged as being crucial to our understanding of our planet's biology and climate. Michael Gross reports.

  16. Science CAP: Curriculum Assistance Program. [Multimedia.

    ERIC Educational Resources Information Center

    DEMCO, Inc., Madison, WI.

    Science Curriculum Assistance Program (Science CAP(TM)) is a multimedia package developed to create a model for preserving classroom science activities that can be shared and customized by teachers. This program is designed to assist teachers in preparing classroom science activities for grades five through eight, and to foster an environment of…

  17. Maintaining and Repairing. CAP Job Function.

    ERIC Educational Resources Information Center

    Ohio State Univ., Columbus. National Center for Research in Vocational Education.

    This Job Function Booklet (Maintaining and Repairing) is one of the 14 components (see note) of the Career Alert Planning (CAP) program, a set of individualized materials designed to help participants find out about themselves and about the kind of work for which they are suited. In this program, participants become acquainted with occupations…

  18. 47 CFR 54.623 - Cap.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 3 2012-10-01 2012-10-01 false Cap. 54.623 Section 54.623 Telecommunication..., Administrator shall calculate the total demand for support submitted by all applicants during the filing window... calculate the amount of support requested by each applicant that has filed during the filing window....

  19. Natural attenuation processes during in situ capping.

    PubMed

    Himmelheber, David W; Pennell, Kurt D; Hughes, Joseph B

    2007-08-01

    Chlorinated solvents are common groundwater contaminants that threaten surface water quality and benthic health when present in groundwater seeps. Aquatic sediments can act as natural biobarriers to detoxify chlorinated solvent plumes via reductive dechlorination. In situ sediment capping, a remedial technique in which clean material is placed at the sediment-water interface, may alter sedimentary natural attenuation processes. This research explores the potential of Anacostia River sediment to naturally attenuate chlorinated solvents under simulated capping conditions. Results of microcosm studies demonstrated that intrinsic dechlorination of dissolved-phase PCE to ethene was possible, with electron donor availability controlling microbial activity. A diverse microbial community was present in the sediment, including multiple Dehalococcoides strains indicated by the amplification of the reductive dehalogenases tceA, vcrA, and bvcA. An upflow column simulating a capped sediment bed subject to PCE-contaminated groundwater seepage lost dechlorination activity with time and only achieved complete dechlorination when microorganisms present in the sediment were provided electron donor. Increases in effluent chloroethene concentrations during the period of biostimulation were attributed to biologically enhanced desorption and the formation of less sorptive dechlorination products. These findings suggest that in situ caps should be designed to account for reductions in natural biobarrier reactivity and for the potential breakthrough of groundwater contaminants.

  20. MSA-capped gold nanoparticle-supported alumina for the determination of Pb and Cd in various environmental water samples

    NASA Astrophysics Data System (ADS)

    Kiran, K.

    2014-11-01

    2-Mercaptosuccinic acid (MSA)-capped gold nanoparticles (GNPs) were used to determine the level of concentration of lead and cadmium metals in various environmental samples. Alumina-coated MSA-capped GNPs easily remove lead and cadmium present in various samples. The absorbance spectrum was obtained at 547 nm. Effects of pH, reagent concentration, interferences, were studied. This method is simple, selective and successfully applied for the determination of lead and cadmium species in various water samples collected in and around four industries.

  1. Fermi energy dependence of the optical emission in core/shell InAs nanowire homostructures

    NASA Astrophysics Data System (ADS)

    Möller, M.; Oliveira, D. S.; Sahoo, P. K.; Cotta, M. A.; Iikawa, F.; Motisuke, P.; Molina-Sánchez, A.; de Lima, M. M., Jr.; García-Cristóbal, A.; Cantarero, A.

    2017-07-01

    InAs nanowires grown by vapor-liquid-solid (VLS) method are investigated by photoluminescence. We observe that the Fermi energy of all samples is reduced by ˜20 meV when the size of the Au nanoparticle used for catalysis is increased from 5 to 20 nm. Additional capping with a thin InP shell enhances the optical emission and does not affect the Fermi energy. The unexpected behavior of the Fermi energy is attributed to the differences in the residual donor (likely carbon) incorporation in the axial (low) and lateral (high incorporation) growth in the VLS and vapor-solid (VS) methods, respectively. The different impurity incorporation rate in these two regions leads to a core/shell InAs homostructure. In this case, the minority carriers (holes) diffuse to the core due to the built-in electric field created by the radial impurity distribution. As a result, the optical emission is dominated by the core region rather than by the more heavily doped InAs shell. Thus, the photoluminescence spectra and the Fermi energy become sensitive to the core diameter. These results are corroborated by a theoretical model using a self-consistent method to calculate the radial carrier distribution and Fermi energy for distinct diameters of Au nanoparticles.

  2. Thermal barrier and support for nuclear reactor fuel core

    DOEpatents

    Betts, Jr., William S.; Pickering, J. Larry; Black, William E.

    1987-01-01

    A thermal barrier/core support for the fuel core of a nuclear reactor having a metallic cylinder secured to the reactor vessel liner and surrounded by fibrous insulation material. A top cap is secured to the upper end of the metallic cylinder that locates and orients a cover block and post seat. Under normal operating conditions, the metallic cylinder supports the entire load exerted by its associated fuel core post. Disposed within the metallic cylinder is a column of ceramic material, the height of which is less than that of the metallic cylinder, and thus is not normally load bearing. In the event of a temperature excursion beyond the design limits of the metallic cylinder and resulting in deformation of the cylinder, the ceramic column will abut the top cap to support the fuel core post.

  3. Nuclear waste vitrification efficiency: cold cap reactions

    SciTech Connect

    Hrma, Pavel R.; Kruger, Albert A.; Pokorny, Richard

    2012-12-15

    The cost and schedule of nuclear waste treatment and immobilization are greatly affected by the rate of glass production. Various factors influence the performance of a waste-glass melter. One of the most significant, and also one of the least understood, is the process of batch melting. Studies are being conducted to gain fundamental understanding of the batch reactions, particularly those that influence the rate of melting, and models are being developed to link batch makeup and melter operation to the melting rate. Batch melting takes place within the cold cap, i.e., a batch layer floating on the surface of molten glass. The conversion of batch to glass consists of various chemical reactions, phase transitions, and diffusion-controlled processes. These include water evaporation (slurry feed contains as high as 60% water), gas evolution, the melting of salts, the formation of borate melt, reactions of borate melt with molten salts and with amorphous oxides (Fe2O3 and Al2O3), the formation of intermediate crystalline phases, the formation of a continuous glass-forming melt, the growth and collapse of primary foam, and the dissolution of residual solids. To this list we also need to add the formation of secondary foam that originates from molten glass but accumulates on the bottom of the cold cap. This study presents relevant data obtained for a high-level-waste melter feed and introduces a one-dimensional (1D) mathematical model of the cold cap as a step toward an advanced three-dimensional (3D) version for a complete model of the waste glass melter. The 1D model describes the batch-to-glass conversion within the cold cap as it progresses in a vertical direction. With constitutive equations and key parameters based on measured data, and simplified boundary conditions on the cold-cap interfaces with the glass melt and the plenum space of the melter, the model provides sensitivity analysis of the response of the cold cap to the batch makeup and melter conditions

  4. NUCLEAR WASTE VITRIFICATION EFFICIENCY COLD CAP REACTIONS

    SciTech Connect

    KRUGER AA; HRMA PR; POKORNY R

    2011-07-29

    The cost and schedule of nuclear waste treatment and immobilization are greatly affected by the rate of glass production. Various factors influence the performance of a waste-glass melter. One of the most significant, and also one of the least understood, is the process of batch melting. Studies are being conducted to gain fundamental understanding of the batch reactions, particularly those that influence the rate of melting, and models are being developed to link batch makeup and melter operation to the melting rate. Batch melting takes place within the cold cap, i.e., a batch layer floating on the surface of molten glass. The conversion of batch to glass consists of various chemical reactions, phase transitions, and diffusion-controlled processes. These include water evaporation (slurry feed contains as high as 60% water), gas evolution, the melting of salts, the formation of borate melt, reactions of borate melt with molten salts and with amorphous oxides (Fe{sub 2}O{sub 3} and Al{sub 2}O{sub 3}), the formation of intermediate crystalline phases, the formation of a continuous glass-forming melt, the growth and collapse of primary foam, and the dissolution of residual solids. To this list we also need to add the formation of secondary foam that originates from molten glass but accumulates on the bottom of the cold cap. This study presents relevant data obtained for a high-level-waste melter feed and introduces a one-dimensional (1D) mathematical model of the cold cap as a step toward an advanced three-dimensional (3D) version for a complete model of the waste glass melter. The 1D model describes the batch-to-glass conversion within the cold cap as it progresses in a vertical direction. With constitutive equations and key parameters based on measured data, and simplified boundary conditions on the cold-cap interfaces with the glass melt and the plenum space of the melter, the model provides sensitivity analysis of the response of the cold cap to the batch makeup

  5. High-pressure jet cutters improve capping operations

    SciTech Connect

    Abel, L.W.; Campbell, P.J.; Bowden, J.R. Sr.

    1995-05-08

    Advances in abrasive cutting technology have improved the methods for removing damaged equipment and preparing wellheads for capping. This technology, much of which was refined during well control operations in Kuwait in 1991, can improve the safety and efficiency of capping jobs by cutting wellheads or casing quickly and cleanly. The majority of well control jobs involve one of three types of capping operations: capping to a flange, capping by installing a wellhead, or capping to a casing stub. Capping operations are often the first major step in regaining control of the well during blowout intervention. Proper planning of a capping operation must take into account the mass flow rate, combustible nature of the flow, well bore geometry, and operations in the post-capping phase of the project. The paper discusses capping vehicles, tree removal, jet cutters, capping to a flange, capping to a stub, swallowing the stub, spin-on technique, capping on fire, stinging, offshore blowouts, firefighting, pollution control, intervention equipment, and rig removal.

  6. Capping in situ with activated carbon in Trondheim harbor (Norway) reduces bioaccumulation of PCBs and PAHs in marine sediment fauna.

    PubMed

    Samuelsson, Göran S; Hedman, Jenny E; Elmquist Kruså, Marie; Gunnarsson, Jonas S; Cornelissen, Gerard

    2015-08-01

    Three types of thin-layer caps with activated carbon (AC) were tested in situ in experimental plots (10 × 10 m) in Trondheim harbor, Norway, using AC + clay, AC-only or AC + sand. One year after capping, intact sediment cores were collected from the amended plots for ex situ surveys of the capping efficiency in reducing the PAH and PCB aqueous concentrations and bioaccumulation by the polychaete Hediste diversicolor and the clam Abra nitida. Reduced pore water concentrations were observed in all AC treatments. The capping efficiency was in general AC + clay > AC-only > AC + sand. AC + clay reduced bioaccumulation of PAH and PCB congeners between 40% and 87% in the worms and between 67% and 97% in the clams. Sediment capped with AC-only also led to reduced bioaccumulation of PCBs, while AC + sand showed no reduction in bioaccumulation. Thus the best thin-layer capping method in this study was AC mixed with clay.

  7. Long-term PAH monitoring results from the Anacostia River active capping demonstration using polydimethylsiloxane (PDMS) fibers.

    PubMed

    Lampert, David J; Lu, Xiaoxia; Reible, Danny D

    2013-03-01

    In this paper, the long-term monitoring results for hydrophobic organic compounds, specifically polycyclic aromatic hydrocarbons (PAHs), from a field demonstration of capping contaminated sediments at the Anacostia River in Washington DC are presented and analyzed. In situ pore water concentrations in field-contaminated sediments in the demonstration caps were quantified using a polydimethylsiloxane (PDMS)-based passive sampling device. High resolution vertical pore water concentration profiles were measured using the device and were used to infer fate and transport of polycyclic aromatics hydrocarbons (PAHs) at the site. The derived pore water concentrations were compared with observed bioaccumulation and solid-phase concentration profiles to infer contaminant migration rates and mechanisms. Observed pore water concentrations were found to be a better predictor of bioaccumulation than solid-phase concentrations. Solid-phase concentrations were low in cores which implied containment of contamination; however pore water profiles showed that contaminant migration had occurred in the first few years after cap placement. The discrepancy is the result of the low sorption capacity of the sand. Because of surface re-contamination, low sorption capacity in the demonstration caps and strong tidal pumping effects, steady state contaminant profiles were reached in the caps several years after placement. Despite re-contamination at the surface, steady state concentrations in the capped areas showed decreased contamination levels relative to the control area.

  8. Taxon interactions control the distributions of cryoconite bacteria colonizing a High Arctic ice cap.

    PubMed

    Gokul, Jarishma K; Hodson, Andrew J; Saetnan, Eli R; Irvine-Fynn, Tristram D L; Westall, Philippa J; Detheridge, Andrew P; Takeuchi, Nozomu; Bussell, Jennifer; Mur, Luis A J; Edwards, Arwyn

    2016-08-01

    Microbial colonization of glacial ice surfaces incurs feedbacks which affect the melting rate of the ice surface. Ecosystems formed as microbe-mineral aggregates termed cryoconite locally reduce ice surface albedo and represent foci of biodiversity and biogeochemical cycling. Consequently, greater understanding the ecological processes in the formation of functional cryoconite ecosystems upon glacier surfaces is sought. Here, we present the first bacterial biogeography of an ice cap, evaluating the respective roles of dispersal, environmental and biotic filtration occurring at local scales in the assembly of cryoconite microbiota. 16S rRNA gene amplicon semiconductor sequencing of cryoconite colonizing a Svalbard ice cap coupled with digital elevation modelling of physical parameters reveals the bacterial community is dominated by a ubiquitous core of generalist taxa, with evidence for a moderate pairwise distance-decay relationship. While geographic position and melt season duration are prominent among environmental predictors of community structure, the core population of taxa appears highly influential in structuring the bacterial community. Taxon co-occurrence network analysis reveals a highly modular community structured by positive interactions with bottleneck taxa, predominantly Actinobacteria affiliated to isolates from soil humus. In contrast, the filamentous cyanobacterial taxon (assigned to Leptolyngbya/Phormidesmis pristleyi) which dominates the community and binds together granular cryoconite are poorly connected to other taxa. While our study targeted one ice cap, the prominent role of generalist core taxa with close environmental relatives across the global cryosphere indicate discrete roles for cosmopolitan Actinobacteria and Cyanobacteria as respective keystone taxa and ecosystem engineers of cryoconite ecosystems colonizing ice caps. © 2016 John Wiley & Sons Ltd.

  9. Effects of subchronic exposures to concentrated ambient particles (CAPs) in mice. III. Acute and chronic effects of CAPs on heart rate, heart-rate fluctuation, and body temperature.

    PubMed

    Hwang, Jing-Shiang; Nadziejko, Christine; Chen, Lung Chi

    2005-04-01

    Normal mice (C57) and mice prone to develop atherosclerosis (ApoE-/-) were implanted with electrocardiograph (EKG), core body temperature, and motion transmitters were exposed daily for 6 h to Tuxedo, NY, concentrated ambient particles (CAPs) for 5 day/wk during the spring and summer of 2003. The series of 5-min EKG monitoring and body-temperature measurements were obtained for each animal in the CAPs and filtered air sham exposure groups. Our hypothesis was that chronic exposure could cause cumulative health effects. We used our recently developed nonparametric method to estimate the daily time periods that mean heart rates (HR), body temperature, and physical activity differed significantly between the CAPs and sham exposed group. CAPs exposure most affected heart rate between 1:30 a.m. and 4:30 a.m. With the response variables being the average heart rate, body temperature, and physical activity, we adopted a two-stage modeling approach to obtain the estimates of chronic and acute effects on the changes of these three response variables. In the first stage, a time-varying model estimated daily crude effects. In the second stage, the true means of the estimated crude effects were modeled with a polynominal function of time for chronic effects, a linear term of daily CAPs exposure concentrations for acute effects, and a random component for unknown noise. A Bayesian framework combined these two stages. There were significant decreasing patterns of HR, body temperature, and physical activity for the ApoE-/- mice over the 5 mo of CAPs exposure, with smaller and nonsignificant changes for the C57 mice. The chronic effect changes of the three response variables for ApoE-/- mice were maximal in the last few weeks. There was also a significant relationship between CAPs exposure concentration and short-term changes of heart rate in ApoE-/- mice during exposure. Response variables were also defined for examining fluctuations of 5-min heart rates within long (i.e., 3-6 h

  10. Model for capping derived from inhibition of surface receptor capping by free fatty acids.

    PubMed Central

    Klausner, R D; Bhalla, D K; Dragsten, P; Hoover, R L; Karnovsky, M J

    1980-01-01

    When low concentrations (2-5 mole %) of cis unsaturated free fatty acids (group A) are intercalated into lymphocyte plasma membrane, capping is inhibited. No effect is seen with trans unsaturated or saturated fatty acids (group B). The capping inhibition is reversible with increasing doses of extracellular calcium. Fluorescence photobleaching recovery has shown that the group A free fatty acids do not inhibit the receptor immobilization associated with patch formation, but inhibit the final energy-dependent movement of the patched receptors into a cap. We have also shown that the group A free fatty acids cause a shift in membrane-bound calcium to the lipid phase from probable protein-associated sites. We have incorporated these findings into a model for capping and membrane-cytoskeletal interactions. Images PMID:6928636

  11. CAPS-1 and CAPS-2 are essential synaptic vesicle priming proteins.

    PubMed

    Jockusch, Wolf J; Speidel, Dina; Sigler, Albrecht; Sørensen, Jakob B; Varoqueaux, Frederique; Rhee, Jeong-Seop; Brose, Nils

    2007-11-16

    Before transmitter-filled synaptic vesicles can fuse with the plasma membrane upon stimulation they have to be primed to fusion competence. The regulation of this priming process controls the strength and plasticity of synaptic transmission between neurons, which in turn determines many complex brain functions. We show that CAPS-1 and CAPS-2 are essential components of the synaptic vesicle priming machinery. CAPS-deficient neurons contain no or very few fusion competent synaptic vesicles, which causes a selective impairment of fast phasic transmitter release. Increases in the intracellular Ca(2+) levels can transiently revert this defect. Our findings demonstrate that CAPS proteins generate and maintain a highly fusion competent synaptic vesicle pool that supports phasic Ca(2+) triggered release of transmitters.

  12. Interaction between Ca/sup + +/-channel antagonists and. cap alpha. /sub 2/-adrenergic receptors in rabbit ileal cell membrane

    SciTech Connect

    Homeidan, F.R.; Wicks, J.; Cusolito, S.; El-Sabban, M.E.; Sharp, G.W.G.; Donowitz, M.

    1986-03-05

    An interaction between Ca/sup + +/-channel antagonists and the ..cap alpha../sub 2/-adrenergic receptor on active electrolyte transport was demonstrated in rabbit ileum. Clonidine, an ..cap alpha../sub 2/-agonist, stimulated NaCl absorption apparently by Ca/sup + +/-channel antagonism since it inhibited /sup 45/Ca/sup + +/ uptake across the basolateral membrane and decreased total ileal calcium content. This stimulation was inhibited by the Ca/sup + +/-channel antagonists dl- and l-verapamil and cadmium but not by nifedipine. The binding of /sup 3/H-yohimbine, a specific ..cap alpha../sub 2/-adrenergic antagonist, was studied on purified ileal cell membranes using a rapid filtration technique. dl-Verapamil and Cd/sup + +/ inhibited the specific binding of /sup 3/H-yohimbine over the same concentration range in which they affected transport. In contrast, nifedipine had no effect on binding, just as it had no effect on clonidine-stimulated NaCl absorption. These data demonstrate that there is an interaction between Ca/sup + +/-channels and ..cap alpha../sub 2/-adrenergic receptors in ileal basolateral membranes. Some Ca/sup + +/-channel antagonists alter ..cap alpha../sub 2/-adrenergic binding to the receptor and ..cap alpha../sub 2/-agonist binding leads to changes in Ca/sup + +/ entry. A close spatial relationship between the Ca/sup + +/-channel and the ..cap alpha../sub 2/-receptor could explain the data.

  13. Calcium-dependent activator protein for secretion 2 (CAPS2) promotes BDNF secretion and is critical for the development of GABAergic interneuron network.

    PubMed

    Shinoda, Yo; Sadakata, Tetsushi; Nakao, Kazuhito; Katoh-Semba, Ritsuko; Kinameri, Emi; Furuya, Asako; Yanagawa, Yuchio; Hirase, Hajime; Furuichi, Teiichi

    2011-01-04

    Calcium-dependent activator protein for secretion 2 (CAPS2) is a dense-core vesicle-associated protein that is involved in the secretion of BDNF. BDNF has a pivotal role in neuronal survival and development, including the development of inhibitory neurons and their circuits. However, how CAPS2 affects BDNF secretion and its biological significance in inhibitory neurons are largely unknown. Here we reveal the role of CAPS2 in the regulated secretion of BDNF and show the effect of CAPS2 on the development of hippocampal GABAergic systems. We show that CAPS2 is colocalized with BDNF, both synaptically and extrasynaptically in axons of hippocampal neurons. Overexpression of exogenous CAPS2 in hippocampal neurons of CAPS2-KO mice enhanced depolarization-induced BDNF exocytosis events in terms of kinetics, frequency, and amplitude. We also show that in the CAPS2-KO hippocampus, BDNF secretion is reduced, and GABAergic systems are impaired, including a decreased number of GABAergic neurons and their synapses, a decreased number of synaptic vesicles in inhibitory synapses, and a reduced frequency and amplitude of miniature inhibitory postsynaptic currents. Conversely, excitatory neurons in the CAPS2-KO hippocampus were largely unaffected with respect to field excitatory postsynaptic potentials, miniature excitatory postsynaptic currents, and synapse number and morphology. Moreover, CAPS2-KO mice exhibited several GABA system-associated deficits, including reduced late-phase long-term potentiation at CA3-CA1 synapses, decreased hippocampal theta oscillation frequency, and increased anxiety-like behavior. Collectively, these results suggest that CAPS2 promotes activity-dependent BDNF secretion during the postnatal period that is critical for the development of hippocampal GABAergic networks.

  14. Calcium-dependent activator protein for secretion 2 (CAPS2) promotes BDNF secretion and is critical for the development of GABAergic interneuron network

    PubMed Central

    Shinoda, Yo; Sadakata, Tetsushi; Nakao, Kazuhito; Katoh-Semba, Ritsuko; Kinameri, Emi; Furuya, Asako; Yanagawa, Yuchio; Hirase, Hajime; Furuichi, Teiichi

    2011-01-01

    Calcium-dependent activator protein for secretion 2 (CAPS2) is a dense-core vesicle-associated protein that is involved in the secretion of BDNF. BDNF has a pivotal role in neuronal survival and development, including the development of inhibitory neurons and their circuits. However, how CAPS2 affects BDNF secretion and its biological significance in inhibitory neurons are largely unknown. Here we reveal the role of CAPS2 in the regulated secretion of BDNF and show the effect of CAPS2 on the development of hippocampal GABAergic systems. We show that CAPS2 is colocalized with BDNF, both synaptically and extrasynaptically in axons of hippocampal neurons. Overexpression of exogenous CAPS2 in hippocampal neurons of CAPS2-KO mice enhanced depolarization-induced BDNF exocytosis events in terms of kinetics, frequency, and amplitude. We also show that in the CAPS2-KO hippocampus, BDNF secretion is reduced, and GABAergic systems are impaired, including a decreased number of GABAergic neurons and their synapses, a decreased number of synaptic vesicles in inhibitory synapses, and a reduced frequency and amplitude of miniature inhibitory postsynaptic currents. Conversely, excitatory neurons in the CAPS2-KO hippocampus were largely unaffected with respect to field excitatory postsynaptic potentials, miniature excitatory postsynaptic currents, and synapse number and morphology. Moreover, CAPS2-KO mice exhibited several GABA system-associated deficits, including reduced late-phase long-term potentiation at CA3–CA1 synapses, decreased hippocampal theta oscillation frequency, and increased anxiety-like behavior. Collectively, these results suggest that CAPS2 promotes activity-dependent BDNF secretion during the postnatal period that is critical for the development of hippocampal GABAergic networks. PMID:21173225

  15. The impact of price-cap regulations on market entry by generic pharmaceutical firms.

    PubMed

    Zhang, Wei; Sun, Huiying; Guh, Daphne; Anis, Aslam H

    2017-04-01

    In 1998, the province of Ontario, Canada implemented price-cap '70/90' regulations: the first generic must be priced at ≤70% of the associated brand-name price and subsequent generics must be priced at ≤90% of the first generics' price. The price-cap was further lowered to 50% in 2006 and 25% in 2010 for all generic drugs regardless of the first or subsequent generic entrants. This study assessed the impact of such price-cap regulations on market entry by generic firms using the formulary database from 9 provinces (January 2004-March 2013). A logistic regression was estimated to compare the probability of entry during the three policy periods in Ontario ('70/90', '25', versus '50'). Since different price-caps were subsequently introduced in other provinces, Alberta, British Columbia, New Brunswick and Saskatchewan, difference-in-differences was used to compare market entry. In Ontario, compared with the period '50', generic firms were 76% and 63% less likely to enter markets in the periods '25' and '70/90', respectively. The difference-in-differences showed that the entry probability decreased the most in Ontario during the '25' period from the '50' period. Lowering the price-cap level to 25% leads to a significantly lower probability of market entry by generic firms.

  16. Gamma-Ray Pulsar Light Curves in Offset Polar Cap Geometry

    NASA Technical Reports Server (NTRS)

    Harding, Alice K.; DeCesar, Megan; Miller, M. Coleman

    2011-01-01

    Recent studies have shown that gamma-ray pulsar light curves are very sensitive to the geometry of the pulsar magnetic field. Pulsar magnetic field geometries, such as the retarded vacuum dipole and force-free magnetospheres, used to model high-energy light curves have distorted polar caps that are offset from the magnetic axis in the direction opposite to rotation. Since this effect is due to the sweepback of field lines near the light cylinder, offset polar caps are a generic property of pulsar magnetospheres and their effects should be included in gamma-ray pulsar light curve modeling. In slot gap models (having two-pole caustic geometry), the offset polar caps cause a strong azimuthal asymmetry of the particle acceleration around the magnetic axis. We have studied the effect of the offset polar caps in both retarded vacuum dipole and force-free geometry on the model high-energy pulse profile. We find that. corn pared to the profile:-; derived from :-;ymmetric caps, the flux in the pulse peaks, which are caustics formed along the trailing magnetic field lines. increases significantly relative to the off-peak emission. formed along leading field lines. The enhanced contrast produces greatly improved slot gap model fits to Fermi pulsar light curves like Vela, which show very little off-peak emIssIon.

  17. Localized field-aligned currents in the polar cap associated with airglow patches

    NASA Astrophysics Data System (ADS)

    Zou, Ying; Nishimura, Yukitoshi; Burchill, Johnathan K.; Knudsen, David J.; Lyons, Larry R.; Shiokawa, Kazuo; Buchert, Stephan; Chen, Steve; Nicolls, Michael J.; Ruohoniemi, J. Michael; McWilliams, Kathryn A.; Nishitani, Nozomu

    2016-10-01

    Airglow patches have been recently associated with channels of enhanced antisunward ionospheric flows propagating across the polar cap from the dayside to nightside auroral ovals. However, how these flows maintain their localized nature without diffusing away remains unsolved. We examine whether patches and collocated flows are associated with localized field-aligned currents (FACs) in the polar cap by using coordinated observations of the Swarm spacecraft, a polar cap all-sky imager, and Super Dual Auroral Radar Network (SuperDARN) radars. We commonly (66% of cases) identify substantial FAC enhancements around patches, particularly near the patches' leading edge and center, in contrast to what is seen in the otherwise quiet polar cap. These FACs have densities of 0.1-0.2 μA/m-2 and have a distribution of width peaking at 75 km. They can be approximated as infinite current sheets that are orientated roughly parallel to patches. They usually exhibit a Region 1 sense, i.e., a downward FAC lying eastward of an upward FAC. With the addition of Resolute Bay Incoherent Scatter radar data, we find that the FACs can close through Pedersen currents in the ionosphere, consistent with the locally enhanced dawn-dusk electric field across the patch. Our results suggest that ionospheric polar cap flow channels are imposed by structures in the magnetospheric lobe via FACs, and thus manifest mesoscale magnetosphere-ionosphere coupling embedded in large-scale convection.

  18. III-V nanocrystals capped with molecular metal chalcogenide ligands: high electron mobility and ambipolar photoresponse.

    PubMed

    Liu, Wenyong; Lee, Jong-Soo; Talapin, Dmitri V

    2013-01-30

    In this work, we synthesized InP and InAs nanocrystals (NCs) capped with different inorganic ligands, including various molecular metal chalcogenide complexes (MCCs) and chalcogenide ions. We found that MCCs and chalcogenide ions can quantitatively displace organic ligands from the surface of III-V NCs and serve as the inorganic capping groups for III-V NC surfaces. These inorganic ligands stabilize colloidal solutions of InP and InAs NCs in polar solvents and greatly facilitate charge transport between individual NCs. Charge transport studies revealed high electron mobility in the films of MCC-capped InP and InAs NCs. For example, we found that bridging InAs NCs with Cu(7)S(4)(-) MCC ligands can lead to very high electron mobility exceeding 15 cm(2)/(V s). In addition, we observed unprecedented ambipolar (positive/negative) photoresponse of MCC-capped InAs NC solids that changed sign depending on the ligand chemistry, illumination wavelength, and doping of the NC solid. For example, the sign of photoconductance of InAs NCs capped with Cu(7)S(4)(-) or Sn(2)S(6)(4-) ions converted from positive at 0.80 and 0.95 eV to negative at 1.27 and 1.91 eV. We propose an explanation of this unusually complex photoconductivity of InAs NC solids.

  19. Lead poisoning

    MedlinePlus

    ... help if this information is not immediately available. Poison Control If someone has severe symptoms from possible ... be caused by lead poisoning, call your local poison control center. Your local poison center can be ...

  20. Specificity of recognition of mRNA 5' cap by human nuclear cap-binding complex.

    PubMed

    Worch, Remigiusz; Niedzwiecka, Anna; Stepinski, Janusz; Mazza, Catherine; Jankowska-Anyszka, Marzena; Darzynkiewicz, Edward; Cusack, Stephen; Stolarski, Ryszard

    2005-09-01

    The heterodimeric nuclear cap-binding complex (CBC) binds to the mono-methylated 5' cap of eukaryotic RNA polymerase II transcripts such as mRNA and U snRNA. The binding is important for nuclear maturation of mRNAs and possibly in the first round of translation and nonsense-mediated decay. It is also essential for nuclear export of U snRNAs in metazoans. We report characterization by fluorescence spectroscopy of the recognition of 5' capped RNA by human CBC. The association constants (K(as)) for 17 mono- and dinucleotide cap analogs as well as for the oligomer m7GpppA(m2') pU(m2')pA(m2') cover the range from 1.8 x 10(6) M(-1) to 2.3 x 10(8) M(-1). Higher affinity for CBC is observed for the dinucleotide compared with mononucleotide analogs, especially for those containing a purine nucleoside next to m7G. The mRNA tetramer associates with CBC as tightly as the dinucleotide analogs. Replacement of Tyr138 by alanine in the CBP20 subunit of CBC reduces the cap affinity except for the mononucleotide analogs, consistent with the crystallographic observation of the second base stacking on this residue. Our spectroscopic studies showed that contrary to the other known cap-binding proteins, the first two nucleotides of a capped-RNA are indispensable for its specific recognition by CBC. Differences in the cap binding of CBC compared with the eukaryotic translation initiation factor 4E (eIF4E) are analyzed and discussed regarding replacement of CBC by eIF4E.