high unblocking temperature: Topics by Science.gov

Sample records for high unblocking temperature

Paleomagnetism of baked sedimentary rocks in the Newark and Culpeper basins: Evidence for the J1 cusp and significant Late Triassic apparent polar wander from the Mesozoic basins of North America

NASA Astrophysics Data System (ADS)

Kodama, Kenneth P.; Cioppa, Maria T.; Sherwood, Elizabeth; Warnock, Andrew C.

1994-08-01

A paleomagnetic study of 14 sites in the baked sedimentary rocks of the Newark basin Passaic Formation in southeastern Pennsylvania reveals two types of magnetic behavior. Dark gray-colored, baked sedimentary rocks have peak unblocking temperatures of 640°C, high magnetic intensities, and shallow, normal polarity, northeasterly directions. Light gray-colored rocks have peak unblocking temperatures of less than 580°C, low magnetic intensities, and intermediate inclination, normal polarity, northwesterly directions. The low unblocking temperature magnetizations are secondary magnetizations which have declinations similar to but are shallower than the B remagnetization observed by Witte and Kent (1991) throughout the Newark basin. The discrepancy may be due to "underprinting" by an unresolved primary magnetization. The low unblocking temperature magnetization was probably acquired by growth of secondary magnetite during a hydrothermal event, as postulated by Sutter (1988), based on geochronologic data. The high unblocking temperature magnetization is significantly prefolding. Both the low-peak unblocking temperature magnetization and the high-peak unblocking temperature magnetization suggest a 15° counterclockwise block rotation of the Sassamansville syncline. If this rotation is removed from the high unblocking temperature sites collected around the fold, a stronger passage of the fold test results. Six sites were also collected from baked sediments and one site from diabase in northern Virginia's Culpeper basin, since Sutter's geochronological work indicated that the intrusives in the Culpeper basin are coeval to the Newark basin intrusives. Virtual geomagnetic poles (VGPs), based on the tilt-corrected, high-temperature Newark basin magnetizations, were compared with the VGPs calculated from the site means of a high-temperature magnetization isolated from baked sedimentary rocks in the Culpeper basin and to the magnetizations reported by Raymond (1982) from dikes and sills. In this comparison the in situ Culpeper poles agreed with the prefolding Newark poles significantly better than the prefolding Culpeper poles. This result indicates that Culpeper intrusives erupted into already tilted sedimentary rocks. The paleomagnetic pole determined from the combined Culpeper baked sediments, dikes, and sills (in situ coordinates) and the Newark basin baked sediments (tilt-corrected coordinates) lies at 60°N, 69°E and is of 201 Ma age. This latest Triassic/earliest Jurassic pole, when combined with the Newark basin Carnian results (Witte and Kent, 1989) and Norian results (Witte et al., 1991) corrected for a counterclockwise block rotation (Kodama et al., 1994), provides a record of significant polar wander from eastern North America's Mesozoic basins for the Late Triassic. This is consistent with observations made for a similar time period from rocks on the Colorado Plateau (Bazard and Butler, 1991). Comparison of the Newark/Culpeper pole to similar age poles from the Kayenta (Bazard and Butler, 1991) and Moenave Formations (Ekstrand and Butler, 1989) only requires small amounts (5°) of Colorado Plateau rotation. The pole also provides the first well-dated evidence of the Jl cusp in North American apparent polar wander from rocks not located on the Colorado Plateau, thus giving strong support for the usefulness of paleomagnetic Euler pole analysis of apparent polar wander.
Directional Cluster Analysis on a Sphere: Retrieval of Archean Magnetic Directions from Data with High Dispersion

NASA Astrophysics Data System (ADS)

Bono, R. K.; Dare, M. S.; Tarduno, J. A.; Cottrell, R. D.

2016-12-01

Magnetic directions from coarse clastic rocks are typically highly scattered, to the point that the null hypothesis that they are drawn from a random distribution, using the iconic test of Watson (1956), cannot be rejected at a high confidence level (e.g. 95%). Here, we use an alternative approach of searching for directional clusters on a sphere. When applied to a new data set of directions from quartzites from the Jack Hills of Western Australia, we find evidence for distinct and meaningful magnetic directions at low (200 to 300 degrees C) and intermediate ( 350 to 450 degrees C) unblocking temperatures, whereas the test of Watson (1956) fails to draw a distinction from random distributions for the ensemble of directions at these unblocking temperature ranges. The robustness of the directional groups identified by the cluster analysis is confirmed by non-parametric resampling tests. The lowest unblocking temperature directional mode appears related to the present day field, perhaps contaminated by viscous magnetizations. The intermediate temperature magnetization matches an overprint recorded by the secondary mineral fuchsite (Cottrell et al., 2016) acquired at ca. 2.65 Ga. These data thus indicate that the Jack Hills carry an overprint at intermediate unblocking temperatures of Archean age. We find no evidence for a 1 Ga remagnetization. In general, the application of cluster analysis on a sphere, with directions confirmed by nonparametric tests, represents a new approach that should be applied when evaluating data with high dispersion, such as those that typically come from weak coarse-grained clastic sedimentary rocks, and/or rocks that have seen several tectonic events that could have imparted multiple magnetic overprints.
High-coercivity, thermally stable and low unblocking temperature magnetic phase: Implications for Archeomagnetic studies

NASA Astrophysics Data System (ADS)

Hartmann, G. A.; Gallet, Y.; Trindade, R. I.; Genevey, A.; Berquo, T. S.; Neumann, R.; Le Goff, M.

2013-05-01

The thermoremanent magnetization in baked clay archeological materials provide very useful information on the time evolution of the Earth's magnetic field over the past few millennia. In these materials, a thermally stable magnetic phase characterized by high coercivities (>400 mT) and low unblocking temperatures (~200 degrees Celsius) has recently been recognized in European bricks, tiles, kilns and hearth samples. Both the identification and the origin of this phase remain, however, poorly constrained. The very same high-coercivity, thermally stable, low unblocking temperature (HCSLT) magnetic phase has been identified in Brazilian bricks fragments dated of the past five centuries. We report here a large set of measurements on a selected collection of samples showing variable contributions of the HCSLT phase. These measurements include low-field magnetic susceptibility vs. temperature curves, hysteresis loops, isothermal remanent magnetization (IRM) acquisition, thermal demagnetization of the three-axis IRM, first order reversal curves (FORC), low-temperature magnetization experiments (remanent magnetization curves and alternating current susceptibility), Mössbauer spectroscopy and X-ray diffraction. Results show the coexistence of low-coercivity magnetic minerals (magnetite and titanomagnetite) and high-coercivity minerals (hematite, HCSLT phase and, in some cases, goethite). We note that the HCSLT magnetic phase is always found in association with hematite. We further observe that the Mössbauer spectroscopy, X-ray diffraction spectra, and the FORC diagrams are also very similar to results previously obtained from annealed clays in which nontronite or iron-rich montmorillonite was transformed into Al-substituted hematite by heating. The HCSLT magnetic phase is thus confidently identified as being hematite with Al substitution. Moreover, considering the abundance of montmorillonite in clay mining settings, we suggest that the widespread occurrence of HCSLT in archeological materials predominantly originates from the transformation of iron-rich montmorillonite during the manufacturing (heating) process.
The inverse microconglomerate test: Definition and application to the preservation of Paleoarchean to Hadean magnetizations in metasediments of the Jack Hills, Western Australia

NASA Astrophysics Data System (ADS)

Cottrell, Rory; Tarduno, John; Bono, Richard; Dare, Matthew

2016-04-01

We introduce a new paleomagnetic field test, the inverse microconglomerate test. In contrast with traditional conglomerate tests, which target specimens that might preserve primary magnetizations, the inverse microconglomerate test focuses on magnetic carriers having unblocking temperatures less than peak metamorphic temperatures. These mineral carriers are expected to carry a consistent direction of remagnetization. Hence, the inverse microconglomerate test evaluates whether coherent magnetizations are retained on a grain/mineral scale in a given sedimentary rock sample. By defining the remagnetization direction, it also serves as a benchmark for comparison of magnetizations from other grains/minerals having unblocking temperatures higher than peak metamorphic conditions (i.e., potential primary magnetizations). We apply this new test to sediments of the Jack Hills (JH), Yilgarn craton, Western Australia. For the JH sediments we focus on fuchsite, a secondary Cr-mica that contains relict Cr-Fe spinels capable of recording remanent magnetizations. We find that JH fuchsite grains retain consistent magnetic directions at unblocking temperatures between ˜270 and 340 oC, which defines a positive test. This direction does not reproduce a nominal 1078-1070 Ma remagnetization reported by Weiss et al. (EPSL, 2015) that we interpret as an artifact of inappropriate use of averaging and statistics. The thermochemical remanent magnetization recorded by the fuchsite was most likely imparted during peak JH metamorphic conditions at ˜2650 Ma. Our inverse microconglomerate test complements a positive microconglomerate test and large scale positive conglomerate test conducted on JH cobbles (Tarduno and Cottrell, EPSL, 2013), further supporting evidence that JH zircons record Paleoarchean to Hadean primary magnetizations at high (greater than 550 oC) unblocking temperatures (Tarduno et al., Science, 2015). More generally, the new inverse microconglomerate test may aid in understanding the timing of peak metamorphism and deformation in complex terrains that have undergone multiple episodes of folding.
Magnetostratigraphy of Early Middle Toarcian expanded sections from the Iberian Range (central Spain)

NASA Astrophysics Data System (ADS)

Osete, María-Luisa; Gialanella, Paola-Romana; Gómez, Juan J.; Villalaín, Juan J.; Goy, Antonio; Heller, Friedrich

2007-07-01

The magnetostratigraphy of the Lower-Middle Toarcian has been established in two well-dated stratigraphically expanded sections: the Sierra Palomera and the Ariño sections, located in the Iberian Range, in central-eastern Spain. Two magnetisation components could be isolated by thermal cleaning: a secondary syntectonic component of always normal polarity unblocking at intermediate temperatures up to 450 °C/475 °C (A component) and a high temperature unblocking component up to 575 °C (B component). The B component passes fold and reversal tests and is considered the characteristic remanent magnetisation of primary origin. The first Toarcian palaeomagnetic pole for Iberia has been obtained: Plat = 77.4°, Plon = 241.3°E (dm = 5.4° dp = 6.0°). Five pairs of normal and reversed polarity zones were calibrated to regional ammonite subzones. The pattern can be calibrated to other Toarcian magnetostratigraphic studies, but provides a more detailed biostratigraphic framework. A refined magnetic polarity time scale is proposed for the Lower-Middle Toarcian.
Cluster analysis on a sphere: Application to magnetizations from metasediments of the Jack Hills, Western Australia

NASA Astrophysics Data System (ADS)

Bono, Richard K.; Tarduno, John A.; Dare, Matthew S.; Mitra, Gautam; Cottrell, Rory D.

2018-02-01

Metasediments of the Jack Hills contain the oldest known terrestrial minerals in the form of zircons nearly 4.4 billion years old. Paleointensity data from these zircons provide evidence for a Hadean geodynamo as old as 4.2 billion years old. Given the importance of these zircons for constraining the earliest history of the core, it is vital to understand the fidelity of the zircon record. A fundamental aspect providing context for the preservation of primary magnetic signals is the nature of overprints predicted to have been imparted on rocks of the Jack Hills due to Archean to Proterozoic metamorphic events. To be viable magnetic records of a Hadean geodynamo, zircon magnetization directions should differ from these secondary magnetizations. To evaluate these secondary magnetizations, we report paleomagnetic analyses of a comprehensive sampling of 68 quartzite cobble-sized clasts from the Jack Hills metasediments ∼0.5 to 1.0 km from the Discovery Site (which has yielded the oldest zircons and paleofield estimates). While application of standard paleomagnetic tests suggests that the ensemble of cobble directions cannot be distinguished from those drawn from a random distribution, a new cluster analysis of directions on a sphere and non-parametric resampling approaches reveal significant directions amongst subsets of the data. One, isolated at the lowest temperature analyzed [200 to 300 °C, Declination (Dec.) = 316.8°, Inclination (Inc.) = - 51.1 °] appears to be dominated by the present day field. Another, isolated at higher (but still relatively low unblocking temperatures that we call "intermediate", of ∼350-500 °C, Dec. = 243.8°, Inc. = 9.5°) agrees with a magnetic overprint isolated from the secondary Cr-Fe mica fuchsite isolated from the Jack Hills Discovery site, passing a field test at the 80% confidence level. No evidence is found in our data, or in the data of others collected on similar Jack Hills lithologies, for a widespread 1 Ga remagnetization event. Instead, we interpret the most prevalent secondary magnetization of the quartzite (i.e., intermediate unblocking) and the fuchsite characteristic remanent magnetization to be ∼2.65 Ga in age, coincident with peak metamorphism (as high as ca. 475 °C) of the Jack Hills. The presence of this distinct secondary magnetization, its difference from that recorded by Jack Hills zircons at high unblocking temperatures, and the lack of a dominant remagnetization direction at high unblocking temperatures in the cobble data (the expected result for a primary magnetization), lends further support to the fidelity of the Hadean geomagnetic record. The presence of the secondary magnetization also lends support to the conclusion that most of the Jack Hills metasediments were deposited in the Archean, with only minor reworking and potential tectonic interleaving of Proterozoic components. Overall, the application of the new directional cluster analysis presented here has the potential to reveal magnetic directions in highly scattered data sets, typical of weakly magnetized coarse-grained sedimentary rocks
Thermal comparison of Infiniti OZil and Signature Ellips phacoemulsification systems.

PubMed

Schmutz, Joseph S; Olson, Randall J

2010-05-01

To determine thermal characteristics of Signature Ellips (Abbott Medical Optics) and Infiniti OZil (Alcon, Inc.) transverse ultrasound and compare both with longitudinal ultrasound in clinically relevant scenarios. Laboratory investigation. Temperature increase over baseline after 60 seconds was measured in water at positions in 90-degree increments around the sleeve near the proximal needle shaft in an artificial chamber for Ellips and OZil on continuous ultrasound with aspiration blocked and unblocked. This was also done with Signature using longitudinal ultrasound, with and without micropulse (6 ms on, 12 ms off), with aspiration blocked and unblocked, and at the OZil sleeve tip on continuous transverse mode with aspiration unblocked. OZil (8.1 +/- 0.3 C) had greater temperature increase than Ellips (5.2 +/- 0.3 C; P < .0001) with aspiration unblocked and blocked (29.3 +/- 1.0 C vs 12.2 +/- 0.7 C; P < .0001). OZil had uneven distribution of heat around the shaft (30.1 +/- 0.5 C vs 28.5 +/- 0.6 C; P < .0001), whereas Ellips did not (P = .57). OZil was cooler at the tip (6.6 +/- 0.2 C; P < .0001). Friction in a cadaver eye incision only increased these numbers by 10% (OZil, irrigation blocked). Metal stress probably creates heat at the proximal needle junction for both transverse methods. Heat generation differences between OZil and Ellips result from the manner in which they create needle motion. Incision burns may occur, especially for OZil, under nonpulsed settings during fragment removal with occlusion when reaching across the anterior chamber such that the proximal needle shaft came near the wound. Copyright 2010 Elsevier Inc. All rights reserved.
New archeomagnetic intensity data from Western Russia

NASA Astrophysics Data System (ADS)

Salnaya, Natasha; Gallet, Yves; Akimova, Stanislava; Antipov, Ilya; Glazunova, Olga

2015-04-01

We recently started a new archeomagnetism research program for Western Russia. The main objective of this project is to recover the geomagnetic field intensity variations in Western Russia over the past two millennia, in order to compare these variations with those already known from Western and Eastern Europe. We sampled several ensembles of baked brick fragments precisely dated by historical constraints between the XIIth and XIVth centuries AD from the archeological site of Novgorod, south of St Petersburg, and between the XVIIth and XVIIIth centuries AD from the Monastery of New Jerusalem located close to Moscow. Most fragments, with a magnetic mineralogy dominated by magnetite, are suitable for archeointensity experiments. For some fragments from Novgorod, the magnetization is carried by a mixture of magnetite and another mineral of high coercivity and low unblocking temperature. The unblocking temperatures are close to 200°C. This mineral, most probably a form of hematite with Al substitutions, is therefore similar to that previously reported from archeological fired-clay artifacts originating from Europe and South America. Archeointensity experiments were conducted using the experimental protocol developed for the Triaxe magnetometer. We will present our first archeointensity results and a preliminary comparison with available European results, mostly from France and Bulgaria.
The Effects of Basolateral Amygdala Lesions on Unblocking

PubMed Central

Chang, Stephen E.; McDannald, Michael A.; Wheeler, Daniel S.; Holland, Peter C.

2012-01-01

Prior reinforcement of a neutral stimulus often blocks subsequent conditioning of a new stimulus if a compound of the original and new cues is paired with the same reinforcer. However, if the value of the reinforcer is altered when the compound is presented, the new cue typically acquires conditioning, a result called unblocking. Blocking, unblocking and related phenomena have been attributed to variations in processing of either the reinforcer, for example, the Rescorla-Wagner (1972) model, or cues, for example, the Pearce-Hall (1980) model. Here, we examined the effects of lesions of the basolateral amygdala on the occurrence of unblocking when the food reinforcer was increased in quantity at the time of introduction of the new cue. The lesions had no effects on unblocking in a simple design (Experiment 1), which did not distinguish between unblocking produced by variations in reward or cue processing. However, in a procedure that distinguished between unblocking due to direct conditioning by the added reinforcer, consistent with the Rescorla-Wagner (1972) model, and that due to increases in conditioning to the original reinforcer, consistent with the Pearce-Hall (1980) and other models of learning, the lesions prevented unblocking of the latter type. These results were discussed in the context of roles of the basolateral amygdala in coding and using reward prediction error information in associative learning. PMID:22448857
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Flexural flow folding and the paleomagnetic fold test: An example of strain reorientation of remancence in the Mauch Chunk formation

NASA Astrophysics Data System (ADS)

Stamatakos, J.; Kodama, K. P.

1991-08-01

The relationship between the remanent magnetization and the detailed strain geometry around a first-order fold in the Appalachian Valley and Ridge Province was investigated to examine whether penetrative strains associated with folding can generate a apparent synfolding geometry from a prefolding magnetization. Paleomagnetic results from the Mississippian Mauch Chunk Formation on both limbs of the Frackville Anticline near Lavelle, Pennsylvania, yield two magnetic components, an intermediate unblocking temperature (300°C-600°C) Kiaman remagnetization and a two-polarity high unblocking temperature (650°C-680°C) characteristic magnetization. When the magnetic directions are incrementally corrected for bedding tilt, the intermediate-temperature component is most tightly clustered at 85% unfolding (D=176°, I=3°) and the high-temperature component is most tightly clustered at 75% unfolding (D=184°, I=27°). Mesoscopic and microscopic structural fabric analyses suggest a strain history that includes a significant component of flexural slip/flow folding. In the coarser-grained sandstone units, folding has largely been accommodated by slip on bedding, while in the finer-grained beds, folding has been accommodated by grain-scale deformation mechanisms such as pressure solution and low-temperature plasticity. Finite strain measurements, determined from center-to-center distances between quartz grains, yield strain ellipsoids consistent with this folding model. Inclination of the characteristic component varies as a function of the magnitude of the finite strain. This variation suggests that the characteristic magnetization has been systematically reoriented with respect to bedding during folding. Remanence directions on the south dipping limb have been rotated to shallower inclinations, while those on the north dipping limb have been rotated to steeper directions causing the prefolding magnetization to appear synfolding. These rotations are in agreement with models of rigid particle rotation in deforming viscous media. Unlike the characteristic magnetization, the secondary component appears to be unaffected by the deformation, and its synfolding behavior is interpreted as the acquisition of a secondary magnetization during Alleghenian folding. These results show that it is important to consider penetrative strains when evaluating the significance of apparent synfolding magnetizations.
Automatic coolant flow control device for a nuclear reactor assembly

DOEpatents

Hutter, E.

1984-01-27

A device which controls coolant flow through a nuclear reactor assembly comprises a baffle means at the exit end of said assembly having a plurality of orifices, and a bimetallic member in operative relation to the baffle means such that at increased temperatures said bimetallic member deforms to unblock some of said orifices and allow increased coolant flow therethrough.
Automatic coolant flow control device for a nuclear reactor assembly

DOEpatents

Hutter, Ernest

1986-01-01

A device which controls coolant flow through a nuclear reactor assembly comprises a baffle means at the exit end of said assembly having a plurality of orifices, and a bimetallic member in operative relation to the baffle means such that at increased temperatures said bimetallic member deforms to unblock some of said orifices and allow increased coolant flow therethrough.
A Spatially Detailed Model of Isometric Contraction Based on Competitive Binding of Troponin I Explains Cooperative Interactions between Tropomyosin and Crossbridges

PubMed Central

Land, Sander; Niederer, Steven A.

2015-01-01

Biophysical models of cardiac tension development provide a succinct representation of our understanding of force generation in the heart. The link between protein kinetics and interactions that gives rise to high cooperativity is not yet fully explained from experiments or previous biophysical models. We propose a biophysical ODE-based representation of cross-bridge (XB), tropomyosin and troponin within a contractile regulatory unit (RU) to investigate the mechanisms behind cooperative activation, as well as the role of cooperativity in dynamic tension generation across different species. The model includes cooperative interactions between regulatory units (RU-RU), between crossbridges (XB-XB), as well more complex interactions between crossbridges and regulatory units (XB-RU interactions). For the steady-state force-calcium relationship, our framework predicts that: (1) XB-RU effects are key in shifting the half-activation value of the force-calcium relationship towards lower [Ca2+], but have only small effects on cooperativity. (2) XB-XB effects approximately double the duty ratio of myosin, but do not significantly affect cooperativity. (3) RU-RU effects derived from the long-range action of tropomyosin are a major factor in cooperative activation, with each additional unblocked RU increasing the rate of additional RU’s unblocking. (4) Myosin affinity for short (1–4 RU) unblocked stretches of actin of is very low, and the resulting suppression of force at low [Ca2+] is a major contributor in the biphasic force-calcium relationship. We also reproduce isometric tension development across mouse, rat and human at physiological temperature and pacing rate, and conclude that species differences require only changes in myosin affinity and troponin I/troponin C affinity. Furthermore, we show that the calcium dependence of the rate of tension redevelopment ktr is explained by transient blocking of RU’s by a temporary decrease in XB-RU effects. PMID:26262582
Preliminary paleomagnetic and rock magnetic results from 17 to 22 ka sediment of Jeju Island, Korea: Geomagnetic excursional behavior or rock magnetic anomalies?

NASA Astrophysics Data System (ADS)

Ahn, Hyeon-Seon; Sohn, Young Kwan; Lee, Jin-Young; Kim, Jin Cheul

2018-05-01

Paleomagnetic and rock magnetic investigations were performed on a 64-cm-thick section of nonmarine unconsolidated muddy sediment from the Gosan Formation on Jeju Island, Korea. This sediment was recently dated to have been deposited between 22 and 17 kyr BP calibrated, with a sedimentation rate of 13-25 cm/kyr, based on many radiocarbon ages. Interestingly, stepwise alternating field (AF) demagnetization revealed characteristic natural remanent magnetizations with anomalous directions, manifested by marked deviations from the direction of today's axial dipole field, for some separate depth levels. On the other hand, stepwise thermal (TH) demagnetization showed more complex behavior, resulting in the identification of multiple remanence components. For all TH-treated specimens, consistently two different components are predominant: a low-temperature component unblocked below 240-320 °C entirely having normal-polarity apparently within the secular variation range of the Brunhes Chron, and a high-temperature component with unblocking temperatures (Tubs) between 240-320 and 520-580 °C that have anomalous directions, concentrated in the 13-34-cm-depth interval ( 17-19 ka in inferred age) and possibly below 53 cm depth (before 20 ka). Rock magnetic results also infer the dominance of low-coercivity magnetic particles having 300 and 580 °C Curie temperature as remanence carriers, suggestive of (titano)maghemite and/or Ti-rich titanomagnetite and magnetite (or Ti-poor titanomagnetite), respectively. A noteworthy finding is that AF demagnetizations in this study often lead to incomplete separation of the two remanence components possibly due to their strongly overlapping AF spectra. The unusual directions do not appear to result from self-reversal remanences. Then, one interpretation is that the low-temperature components are attributable to post-depositional chemical remanences, associated possibly with the later formation of the mineral phase having Tub 300 °C, whereas the high-temperature components are of primary detrital origin that survived later chemical influence. Accordingly, the unusual directions might record geomagnetic instability within the 17-22 ka period manifested by multiple excursional swings, partly associated with the Tianchi/Hilina Pali excursion. However, further work is needed to verify this interpretation and distinguish it from alternative explanations that invoke rock magnetic complexities as the cause of the unusual directions.[Figure not available: see fulltext.
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Paleomagnetic and Rock Magnetic Study of Oligocene-Holocene Sedimentary Rocks from Northern Dominican Republic: Evidence of Vertical Axis Rotations

NASA Astrophysics Data System (ADS)

Anson Sanchez, M.; Kodama, K. P.; Pueyo, E. L.; Soto, R.; Garcia-Senz, J.; Escuder-Viruete, J.; Pastor-Galan, D.

2017-12-01

A paleomagnetic and rock magnetic study was conducted in the northern Dominican Republic to detect vertical axis rotations in an active left-lateral, strike slip fault zone. 191 samples from 21 sites were collected from a variety of lithologies including limestones, conglomerates, calcarenites and marls that ranged in age from the Oligocene to the Holocene. The rock magnetic portion of the study focused on the identification of magnetic minerals using coercivity, and Curie temperature (c vs temperature) measurement, modeling of IRM acquisition curves, and thermal demagnetization of IRMs (Lowrie, 19901). In the paleomagnetic portion of the study characteristic remanences (ChRMs) were isolated using thermal demagnetization (19 steps up to 680ºC) and alternating field (AF) demagnetization (17 steps up to 100 mT). In most cases the characteristic remanence is carried by magnetite, with peak unblocking temperatures of 575ºC. This interpretation was supported by c vs. T results that yielded Curie temperatures of 580˚C. In only a few cases (7 samples) higher unblocking temperatures suggested hematite as the magnetic carrier. The modeling of IRM acquisition curves, that shows two coercivity components, further supports the presence of magnetite. 75% of the IRM is carried by the low-coercivity component (100-300 mT, magnetite). 25% of the IRM is carried by the high-coercivity component (1.2-1.6T) characteristic of hematite. The IRM acquisition data was collected from 24 samples (3-4 from each of the lithologies sampled). IRMs were acquired in fields from 4mT to 1T in 23 steps. The paleomagnetic results show a grouping by tectonic blocks with one group having westerly ChRM declinations (268˚-295˚) and a second group having northerly ChRM declinations (357˚-035˚). In most cases, inclinations are intermediate ( 35˚), in agreement with the 24˚-31˚ expected inclinations for Dominican Republic in the period Oligocene to Holocene. The rotation of the tectonic blocks, as detected by the declinations, is consistent with a left-lateral strike-slip motion across the main fault in the area. 1Lowrie, 1990, GRL, 17, 159-162
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Nuclear structure properties and stellar weak rates for 76Se: Unblocking of the Gamow Teller strength

NASA Astrophysics Data System (ADS)

Nabi, Jameel-Un; Ishfaq, Mavra; Böyükata, Mahmut; Riaz, Muhammad

2017-10-01

At finite temperatures (≥ 107K), 76Se is abundant in the core of massive stars and electron capture on 76Se has a consequential role to play in the dynamics of core-collapse. The present work may be classified into two main categories. In the first phase we study the nuclear structure properties of 76Se using the interacting boson model-1 (IBM-1). The IBM-1 investigations include the energy levels, B (E 2) values and the prediction of the geometry. We performed the extended consistent-Q formalism (ECQF) calculation and later the triaxial formalism calculation (constructed by adding the cubic term to the ECQF). The geometry of 76Se can be envisioned within the formalism of the potential energy surface based on the classical limit of IBM-1 model. In the second phase, we reconfirm the unblocking of the Gamow-Teller (GT) strength in 76Se (a test case for nuclei having N > 40 and Z < 40). Using the deformed pn-QRPA model we calculate GT transitions, stellar electron capture cross section (within the limit of low momentum transfer) and stellar weak rates for 76Se. The distinguishing feature of our calculation is a state-by-state evaluation of stellar weak rates in a fully microscopic fashion. Results are compared with experimental data and previous calculations. The calculated GT distribution fulfills the Ikeda sum rule. Rates for β-delayed neutrons and emission probabilities are also calculated. Our study suggests that at high stellar temperatures and low densities, the β+-decay on 76Se should not be neglected and needs to be taken into consideration along with electron capture rates for simulation of presupernova evolution of massive stars.
31 CFR 586.517 - Unblocking of certain debt.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 31 Money and Finance: Treasury 3 2010-07-01 2010-07-01 false Unblocking of certain debt. 586.517 Section 586.517 Money and Finance: Treasury Regulations Relating to Money and Finance (Continued) OFFICE OF FOREIGN ASSETS CONTROL, DEPARTMENT OF THE TREASURY FEDERAL REPUBLIC OF YUGOSLAVIA (SERBIA...
75 FR 79444 - Unblocking of Specially Designated National and Blocked Person Pursuant To Executive Order 13348

Federal Register 2010, 2011, 2012, 2013, 2014

2010-12-20

... Prohibiting the Importation of Certain Goods from Liberia.'' DATES: The unblocking and removal from the list... unlawful depletion of Liberian resources and their removal from Liberia, and secreting of Liberian funds and property, undermined Liberia's transition to democracy, the orderly development of Liberia's...
31 CFR 500.505 - Certain persons unblocked.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 31 Money and Finance: Treasury 3 2010-07-01 2010-07-01 false Certain persons unblocked. 500.505 Section 500.505 Money and Finance: Treasury Regulations Relating to Money and Finance (Continued) OFFICE... a jurisdiction in, the United States or the authorized trade territory who or which has never been a...
31 CFR 500.307 - Unblocked national.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 31 Money and Finance: Treasury 3 2010-07-01 2010-07-01 false Unblocked national. 500.307 Section 500.307 Money and Finance: Treasury Regulations Relating to Money and Finance (Continued) OFFICE OF...” shall not be deemed to suspend in any way the requirements of any section of this chapter relating to...
76 FR 60130 - Unblocking of Specially Designated Nationals and Blocked Persons Pursuant to the Cuban Assets...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-09-28

... removal from the list of Specially Designated Nationals and Blocked Persons (``SDN List'') of the... INFORMATION: Electronic and Facsimile Availability The SDN List and additional information concerning OFAC are... service at (202) 622-0077. Background On September 21, 2011, OFAC unblocked and removed from the SDN List...
31 CFR 515.505 - Certain Cuban nationals unblocked; transactions of certain other Cuban nationals lawfully present...

Code of Federal Regulations, 2014 CFR

2014-07-01

... nationals who have taken up permanent residence outside of Cuba. 515.505 Section 515.505 Money and Finance... residence outside of Cuba. (a) General license unblocking certain persons. The following persons are... national; and (2) Any entity that otherwise would be a national of Cuba solely because of the interest...
31 CFR 515.505 - Certain Cuban nationals unblocked; transactions of certain other Cuban nationals lawfully present...

Code of Federal Regulations, 2011 CFR

2011-07-01

... nationals who have taken up permanent residence outside of Cuba. 515.505 Section 515.505 Money and Finance... residence outside of Cuba. (a) General license unblocking certain persons. The following persons are... national; and (2) Any entity that otherwise would be a national of Cuba solely because of the interest...
31 CFR 515.505 - Certain Cuban nationals unblocked; transactions of certain other Cuban nationals lawfully present...

Code of Federal Regulations, 2012 CFR

2012-07-01

... nationals who have taken up permanent residence outside of Cuba. 515.505 Section 515.505 Money and Finance... residence outside of Cuba. (a) General license unblocking certain persons. The following persons are... national; and (2) Any entity that otherwise would be a national of Cuba solely because of the interest...
31 CFR 515.505 - Certain Cuban nationals unblocked; transactions of certain other Cuban nationals lawfully present...

Code of Federal Regulations, 2013 CFR

2013-07-01

... nationals who have taken up permanent residence outside of Cuba. 515.505 Section 515.505 Money and Finance... residence outside of Cuba. (a) General license unblocking certain persons. The following persons are... national; and (2) Any entity that otherwise would be a national of Cuba solely because of the interest...
Paleomagnetism of the Red Lake greenstone belt, northwestern Ontario: Possible evidence for the timing of gold mineralization

NASA Astrophysics Data System (ADS)

Constanzo-Alvarez, Vincenzo; Dunlop, David J.

1993-10-01

We report paleomagnetic results from (1) largely unaltered batholiths and (2) sheared and altered units in the Archean Red Lake greenstone belt, a major gold-producing region in the Uchi subprovince of northwestern Ontario. Group 1 includes the Hammell Lake, Killala Baird, Trout Lake and Little Vermilion Lake batholiths, which were intruded between 2730 and 2700 Ma ago (U/Pb, zircon). Group 2 includes the Howey diorite, the Dome Stock, and dikes and andesites from the Dickenson mine. These units, from the mineralized deformation zones (DZs) between the batholiths, were sheared and hydrothermally altered in the same event that caused gold mineralization in supracrustal units. The batholiths carry a stable reversed remanence (RLR), with D = 159 deg, I = -74 deg (k = 20, alpha(sub 95) = 16 deg, N = 4 units, 14 sites). RLR has high coercivities, unblocking temperatures and remanence intensities an appears to be a primary thermal remanence dating from approximately 2700 ma. The altered units from the gold-bearing Dzs carrying a different remanence (RLG), with D = 180 deg, I = -57 deg (k = 23, alpha (sub 95) = 3 deg, N = 3 units, 6 sites). RLG also has relatively high coercivities and unblocking temperatures but its magnetization intensities are 1-2 orders of magnitude lower than those of RLR. Opaque minerals and silicates observed in thin section are highly altered. RLG is therfore believed to be a chemical or thermochemical remanence acquired approximately 2580 Ma ago during the late stages of cooling and gold mineralization. Seeing as RLG characterizes the shear zone rocks but is absent from unaltered rocks outside the DZs, it could be used as a rapid prospecting tool in delineating areas of alteration and posible mineralization. The palepoles for RLR (approximately 2700 Ma) and RLG (approximately 2580 Ma) link with those of the Shelley Lake granite (2580 Ma, Ar-40/Ar-39, hornblende and biotite) and the Matachewan/Hearst dikes (2450 Ma, U/Pb, zircon and baddeleyite). The sense of motion on the late Archean-early Proterozoic apparent polar wander path for Laurentia, as defined by this sequence of pale poles, is opposite to that previously accepted.
A two‐point scheme for optimal breast IMRT treatment planning

PubMed Central

2013-01-01

We propose an approach to determining optimal beam weights in breast/chest wall IMRT treatment plans. The goal is to decrease breathing effect and to maximize skin dose if the skin is included in the target or, otherwise, to minimize the skin dose. Two points in the target are utilized to calculate the optimal weights. The optimal plan (i.e., the plan with optimal beam weights) consists of high energy unblocked beams, low energy unblocked beams, and IMRT beams. Six breast and five chest wall cases were retrospectively planned with this scheme in Eclipse, including one breast case where CTV was contoured by the physician. Compared with 3D CRT plans composed of unblocked and field‐in‐field beams, the optimal plans demonstrated comparable or better dose uniformity, homogeneity, and conformity to the target, especially at beam junction when supraclavicular nodes are involved. Compared with nonoptimal plans (i.e., plans with nonoptimized weights), the optimal plans had better dose distributions at shallow depths close to the skin, especially in cases where breathing effect was taken into account. This was verified with experiments using a MapCHECK device attached to a motion simulation table (to mimic motion caused by breathing). PACS number: 87.55 de PMID:24257291
Paleomagnetic Results of the 925 Ma Mafic Dykes From the North China Craton: Implications for the Neoproterozoic Paleogeography of Rodinia

NASA Astrophysics Data System (ADS)

Zhao, X.; Peng, P.

2017-12-01

Precambrian mafic dyke swarms are useful geologic records for Neoproterozoic paleogeographic reconstruction. We present a paleomagnetic study of the 925 Ma Dashigou dyke swarm from 3 widely separated locations in the central and northern parts of the North China Craton, which are previously unsampled regions. Stepwise thermal and alternating field demagnetizations were successful in isolating two magnetic components. The lower unblocking temperature component represents the recent Earth magnetic field. The higher unblocking temperature component is the characteristic remanent magnetization and yields positive baked contact test. Results from detailed rock magnetic measurements corroborate the demagnetization behavior and show that titanomagnetites are the main magnetic carrier in these rocks. There was no regional event that has reset the remanent magnetization of all the dyke sites, as indicated by the magnetization directions of both overlying and underlying strata. The similarity of the virtual paleomagnetic poles for the 3 sampled regions also argues that the characteristic remanent magnetizations are primary magnetization when the dykes were emplaced. The paleomagnetic poles from the Dashigou dyke swarm of the North China Craton are not similar to those of the identical aged Bahia dykes from the São Francisco Craton, Brazil, indicating that these mafic dykes may be not parts of a common regional magmatic event that affected North China Craton and NE Brazil at about 925 Ma.
Partial self-reversal of TRM in baked soils and ceramics from Ecuador

NASA Astrophysics Data System (ADS)

Roperch, Pierrick; Chauvin, Annick; Valdez, Francisco

2012-11-01

Partial self-reversed thermoremanent magnetizations (SRTRMs) were observed in samples of baked soils, hearths and ceramics from the Rumipamba archeological site near Quito (Ecuador) and ceramics from sites near the town of Esmeraldas (Ecuador). The SRTRMs were recognized at room temperature on few samples but cooling the samples in liquid nitrogen enhanced the intensity of the SRTRM and measurement at 77°K enables its rapid detection in many samples from these sites. Alternating field demagnetization of the SRTRM indicate median destructive field of the order of 50 mT and thermal demagnetization give unblocking temperatures in the temperature range 280-380 °C. The magnetic carriers of the SRTRM are stable to heating in air or in vacuum up to 600 °C suggesting that titanomaghemite should not be the magnetic carrier of the SRTRM. The studied baked clays and ceramics contain detrital material of mainly volcanic origin. Ti-poor titanomagnetite is the main magnetic carrier identified by strong field data or susceptibility measurements versus temperature. Ilmeno-hematite grains were recognized with microscope observations under reflected light. Scanning electron microscope observations with energy dispersive X-ray spectrometry indicate a Ti/Fe ratio corresponding to an ilmenite content of ˜0.55. We also compared the magnetic properties of the partially self-reversed baked clays with those of the self-reversed Pinatubo pumices. The SRTRMs were measured upon cooling from room temperature to 20°K with the MPMS. Upon cooling to 20°K the SRTRM show a nearly tenfold increase in intensity with respect to the room temperature measurement. The baked clay and ceramics from Ecuador carrying the SRTRM share similar magnetic properties with the Pinatubo pumices (unblocking temperatures, low temperature behavior) supporting the interpretation that detrital hemoilmenite originating from the Holocene activity of the numerous Ecuadorian volcanoes is the main carrier of the SRTRM in the archeological samples. In some samples, anisotropy tensors of SRTRM show large anisotropy degree (>2). The high anisotropy observed when the total magnetization is the sum of a normal thermoremanent magnetization (TRM) and a SRTRM is likely amplified because the anisotropy carried by the SRTRM is larger than the one carried by the normal component. A component of SRTRM may be hidden in archeological materials containing detrital hemoilmenites related to dacitic/andesitic volcanism and this may affect the determination of paleointensity of the earth magnetic field especially when non thermal method are used.
76 FR 62605 - Virginia Graeme Baker Pool and Spa Safety Act; Interpretation of Unblockable Drain

Federal Register 2010, 2011, 2012, 2013, 2014

2011-10-11

... the VGB Act defines an ``unblockable drain'' as ``a drain of any size and shape that a human body...'' as follows: A suction outlet defined as all components, including the sump and/or body, cover/grate...'' Body Blocking Element of ASME/ANSI A112.19.8-2007 and that the rated flow through the remaining open...
An innovative, highly sensitive receiver system for the Square Kilometre Array Mid Radio Telescope

NASA Astrophysics Data System (ADS)

Tan, Gie Han; Lehmensiek, Robert; Billade, Bhushan; Caputa, Krzysztof; Gauffre, Stéphane; Theron, Isak P.; Pantaleev, Miroslav; Ljusic, Zoran; Quertier, Benjamin; Peens-Hough, Adriaan

2016-07-01

The Square Kilometre Array (SKA) Project is a global science and engineering project realizing the next-generation radio telescopes operating in the metre and centimetre wavelengths regions. This paper addresses design concepts of the broadband, exceptionally sensitive receivers and reflector antennas deployed in the SKA1-Mid radio telescope to be located in South Africa. SKA1-Mid (350 MHz - 13.8 GHz with an option for an upper limit of 24 GHz) will consist of 133 reflector antennas using an unblocked aperture, offset Gregorian configuration with an effective diameter of 15 m. Details on the unblocked aperture Gregorian antennas, low noise front ends and advanced direct digitization receivers, are provided from a system design perspective. The unblocked aperture results in increased aperture efficiency and lower side-lobe levels compared to a traditional on-axis configuration. The low side-lobe level reduces the noise contribution due to ground pick-up but also makes the antenna less susceptible to ground-based RFI sources. The addition of extra shielding on the sub-reflector provides a further reduction of ground pick-up. The optical design of the SKA1-Mid reflector antenna has been tweaked using advanced EM simulation tools in combination with sophisticated models for sky, atmospheric and ground noise contributions. This optimal antenna design in combination with very low noise, partially cryogenic, receivers and wide instantaneous bandwidth provide excellent receiving sensitivity in combination with instrumental flexibility to accommodate a wide range of astronomical observation modes.
Assessing New and Old Methods in Paleomagnetic Paleothermometry: A Test Case at Mt. St. Helens, USA

NASA Astrophysics Data System (ADS)

Bowles, J. A.; Gerzich, D.; Jackson, M. J.

2017-12-01

Paleomagnetic data can be used to estimate deposit temperatures (Tdep) of pyroclastic density currents (PDCs). The typical method is to thermally demagnetize oriented lithic clasts incorporated into the PDC. If Tdep is less than the maximum Curie temperature (Tc), the clast is partially remagnetized in the PDC, and the unblocking temperature (Tub) at which this remagnetization is removed is an estimate of Tdep. In principle, juvenile clasts can also be used, and Tub-max is taken as the minimum Tdep. This all assumes blocking (Tb) and unblocking temperatures are equivalent and that the blocking spectrum remains constant through time. Recent evidence shows that Tc in many titanomagnetites is a strong function of thermal history due to a crystal-chemical reordering process. We therefore undertake a study designed to test some of these assumptions and to assess the extent to which the method may be biased by a Tb spectrum that shifts to higher T during cooling. We also explore a new magnetic technique that relies only on stratigraphic variations in Tc. Samples are from the May 18, 1980 PDCs at Mt. St. Helens, USA. Direct temperature measurements of the deposits were 297 - 367°C. At sites with oriented lithics, standard methods provide a Tdep range that overlaps with measured temperatures, but is systematically higher by a few 10s of °C. By contrast, pumice clasts all give Tdep_min estimates that greatly exceed lithic estimates and measured temperatures. We attribute this overestimate to two causes: 1) Tc and Tub systematically increase with depth as a result of the reordering process. This results in Tdep_min estimates that vary by 50°C and increase with depth. 2) MSH pumice is multi-domain, where Tub > Tb, resulting in a large overestimate in Tdep. At 5 sites, stratigraphic variations in Tc were conservatively interpreted in terms of Tdep as <300°C or >300°C. More sophisticated modeling of the time-temperature-depth evolution of Tc allows us to place tighter constraints on some deposits, and our preliminary interpretation suggests that PDC pulses became successively hotter throughout the day. This new method allows us to evaluate subtle temporal/spatial variabilities that may not be evident from direct measurements made at the surface. It also allows Tdep estimates to be made on PDCs where no lithic clasts are present.

Temperature Effects on Kinetics of KV11.1 Drug Block Have Important Consequences for In Silico Proarrhythmic Risk Prediction.

PubMed

Windley, Monique J; Mann, Stefan A; Vandenberg, Jamie I; Hill, Adam P

2016-07-01

Drug block of voltage-gated potassium channel subtype 11.1 human ether-a-go-go related gene (Kv11.1) (hERG) channels, encoded by the KCNH2 gene, is associated with reduced repolarization of the cardiac action potential and is the predominant cause of acquired long QT syndrome that can lead to fatal cardiac arrhythmias. Current safety guidelines require that potency of KV11.1 block is assessed in the preclinical phase of drug development. However, not all drugs that block KV11.1 are proarrhythmic, meaning that screening on the basis of equilibrium measures of block can result in high attrition of potentially low-risk drugs. The basis of the next generation of drug-screening approaches is set to be in silico risk prediction, informed by in vitro mechanistic descriptions of drug binding, including measures of the kinetics of block. A critical issue in this regard is characterizing the temperature dependence of drug binding. Specifically, it is important to address whether kinetics relevant to physiologic temperatures can be inferred or extrapolated from in vitro data gathered at room temperature in high-throughout systems. Here we present the first complete study of the temperature-dependent kinetics of block and unblock of a proarrhythmic drug, cisapride, to KV11.1. Our data highlight a complexity to binding that manifests at higher temperatures and can be explained by accumulation of an intermediate, non-blocking encounter-complex. These results suggest that for cisapride, physiologically relevant kinetic parameters cannot be simply extrapolated from those measured at lower temperatures; rather, data gathered at physiologic temperatures should be used to constrain in silico models that may be used for proarrhythmic risk prediction. Copyright © 2016 by The American Society for Pharmacology and Experimental Therapeutics.
Palaeomagnetic constraints on the evolution of the Atlantis Massif oceanic core complex (Mid-Atlantic Ridge, 30°N)

NASA Astrophysics Data System (ADS)

Morris, A.; Pressling, N.; Gee, J. S.

2012-04-01

Oceanic core complexes expose lower crustal and upper mantle rocks on the seafloor by tectonic unroofing in the footwalls of large-slip detachment faults. They represent a fundamental component of the seafloor spreading system at slow and ultraslow axes. One of the most extensively studied oceanic core complexes is Atlantis Massif, located at 30°N at the intersection of the Atlantis Transform Fault and the Mid Atlantic Ridge (MAR). The central dome of the massif exposes the corrugated detachment fault surface and was drilled during IODP Expedition 304/305 (Hole U1309D). This sampled a 1.4 km faulted and complexly layered footwall section dominated by gabbroic lithologies with minor ultramafic rocks. Palaeomagnetic analyses demonstrate that the gabbroic sequences at Atlantis Massif carry highly stable remanent magnetizations that provide valuable information on the evolution of the section. Thermal demagnetization experiments recover high unblocking temperature components of reversed polarity (R1) throughout the gabbroic sequences. Correlation of structures observed on oriented borehole (FMS) images and those recorded on unoriented core pieces allows reorientation of R1 remanences. The mean remanence direction in true geographic coordinates constrains the tectonic rotation experienced by the Atlantis Massif footwall, indicating a 46°±6° counterclockwise around a MAR-parallel horizontal axis trending 011°±6°. The detachment fault therefore initiated at a steep dip of >50° and then rotated flexurally to its present day low angle geometry (consistent with a 'rolling-hinge' model for detachment evolution). In a number of intervals, the gabbros exhibit a complex remanence structure with the presence of additional intermediate temperature normal (N1) and lower temperature reversed (R2) polarity components, suggesting an extended period of remanence acquisition during different polarity intervals. Sharp break-points between different polarity components suggest that they were acquired by a thermal mechanism. There appears to be no correlation between remanence structure and either the igneous stratigraphy or the distribution of alteration in the core. Instead, the remanence data are consistent with a model in which the lower crustal section acquired magnetizations of different polarity during a protracted cooling history spanning two geomagnetic reversals. The crystallization age of the section (1.2 Ma; derived from Pb/U zircon dating) suggests that the R1 component was acquired during geomagnetic polarity chron C1r.2r, N1 during chron C1r.1n (Jaramillo) and R2 during chron C1r.1r. By considering the maximum time intervals available for acquisition of the N1 and R2 components and correcting laboratory unblocking temperatures accordingly, the data provide additional constraints on the thermal evolution of the Atlantis Massif footwall.
Palaeomagnetic constraints on the evolution of the Atlantis Massif oceanic core complex (Mid-Atlantic Ridge, 30°N)

NASA Astrophysics Data System (ADS)

Morris, A.; Pressling, N.; Gee, J. S.

2011-12-01

Oceanic core complexes expose lower crustal and upper mantle rocks on the seafloor by tectonic unroofing in the footwalls of large-slip detachment faults. They represent a fundamental component of the seafloor spreading system at slow and ultraslow axes. One of the most extensively studied oceanic core complexes is Atlantis Massif, located at 30°N at the intersection of the Atlantis Transform Fault and the Mid Atlantic Ridge (MAR). The central dome of the massif exposes the corrugated detachment fault surface and was drilled during IODP Expedition 304/305 (Hole U1309D). This sampled a 1.4 km faulted and complexly layered footwall section dominated by gabbroic lithologies with minor ultramafic rocks. Palaeomagnetic analyses demonstrate that the gabbroic sequences at Atlantis Massif carry highly stable remanent magnetizations that provide valuable information on the evolution of the section. Thermal demagnetization experiments recover high unblocking temperature components of reversed polarity (R1) throughout the gabbroic sequences. Correlation of structures observed on oriented borehole (FMS) images and those recorded on unoriented core pieces allows reorientation of R1 remanences. The mean remanence direction in true geographic coordinates constrains the tectonic rotation experienced by the Atlantis Massif footwall, indicating a 46°±6° counterclockwise around a MAR-parallel horizontal axis trending 011°±6°. The detachment fault therefore initiated at a steep dip of >50° and then rotated flexurally to its present day low angle geometry (consistent with a 'rolling-hinge' model for detachment evolution). In a number of intervals, the gabbros exhibit a complex remanence structure with the presence of additional intermediate temperature normal (N1) and lower temperature reversed (R2) polarity components, suggesting an extended period of remanence acquisition during different polarity intervals. Sharp break-points between different polarity components suggest that they were acquired by a thermal mechanism. There appears to be no correlation between remanence structure and either the igneous stratigraphy or the distribution of alteration in the core. Instead, the remanence data are consistent with a model in which the lower crustal section acquired magnetizations of different polarity during a protracted cooling history spanning two geomagnetic reversals. The crystallization age of the section (1.2 Ma; derived from Pb/U zircon dating) suggests that the R1 component was acquired during geomagnetic polarity chron C1r.2r, N1 during chron C1r.1n (Jaramillo) and R2 during chron C1r.1r. By considering the maximum time intervals available for acquisition of the N1 and R2 components and correcting laboratory unblocking temperatures accordingly, the data provide additional constraints on the thermal evolution of the Atlantis Massif footwall.
Geomagnetic Reversals of the Late Jurassic and Early Cretaceous Captured in a North China Core

NASA Astrophysics Data System (ADS)

Kuhn, T.; Fu, R. R.; Kent, D. V.; Olsen, P. E.

2016-12-01

The Tuchengzi formation in North China nominally spans nearly 20 million years of the Late Jurassic and Early Cretaceous, an interval during which age calibration of the Geomagnetic Polarity Time Scale (GPTS) based on seafloor magnetic anomalies is poorly known. The overlying Yixian formation is of special paleontological interest due to an abundance of spectacularly preserved macrofossils of feathered non-avian dinosaurs, birds, mammals, and insects. Scarce fossils in the Tuchengzi, sparse accurate radiometric dates on both the Tuchengzi and overlying Yixian formation, and scant previous paleomagnetic studies on these formations motivated our application of magnetostratigraphy as a geochronological tool. We constructed a geomagnetic reversal sequence from the upper 142m of a 200m core extracted in Liaoning Province at Huangbanjigou spanning the lower Yixian Formation and the unconformably underlying Tuchengzi Formation. Thermal demagnetization up to 680°C in steps of 25-50°C revealed predominantly normal overprints consistent with the modern day field with unblocking temperatures between 125°C and as high as 550°C, as well as normal and reverse characteristic components with unblocking temperatures between 500°C and 680°C. Going up from the base of the core, there is a reverse polarity magnetozone >6m thick, followed by a 5m normal magnetozone, a 10m reverse magnetozone, a 25m normal magnetozone, and a 6m reverse magnetozone truncated by the Yixian-Tuchengzi unconformity. Above the unconformity, all 81m of core were normal. These results indicate that a meaningful polarity stratigraphy can be recovered from the Tuchengzi and Yixian formations that will be invaluable for correlations across the Tuchengzi and potentially the Yixian formations, which span thousands of square kilometers and vary in thickness by many hundreds of meters. The results also demonstrate that, in combination with accurate and precise radiometric dates, the Tuchengzi Formation has the potential to provide tight constraints on presently poorly constrained Late Jurassic and Early Cretaceous parts of the GPTS and provide an independent reversal time scale by which seafloor-anomaly based time scales can be refined.
The Importance of Outreach Programs to Unblock the Pipeline and Broaden Diversity in ICT Education

ERIC Educational Resources Information Center

Lang, Catherine; Craig, Annemieke; Egan, Mary Anne

2016-01-01

There is a need for outreach programs to attract a diverse range of students to the computing discipline. The lack of qualified computing graduates to fill the growing number of computing vacancies is of concern to government and industry and there are few female students entering the computing pipeline at high school level. This paper presents…
Palaeointensity determinations on rocks from the Achaean- Paleoproterozoic dykes from the Karelian craton

NASA Astrophysics Data System (ADS)

Shcherbakov, Valera; Shcherbakova, Valentina; Lubnina, Natalia; Zhidkov, Grigory; Tsel'movich, Vladimir

2017-04-01

The Karelian craton was a fragment of either an earlier late Archean supercontinent, sometimes referred to as Kenorland. Now the craton is a large Archean composite granite-greenstone terrane in the eastern part of the Fennoscandian Shield bounded by Paleoproterozoic Svecofennian orogen in the south-west and by Lapland-Kola orogen in the north-east and Belomorian province in the east-north-east. Mafic dykes, volcanic rocks, sills, and layered intrusions with ages of ca. 2.51-2.45 Ga and ca. 2.06-1.95 Ga are widespread and well-studied in the Karelian Craton. Paleointensity (Banc) results obtained on the Shala dike (age of 2504 Ma by U-Pb, ID TIMS) tracked near vl. Shala and on the Deda island are discussed here. Eighteen block samples of gabbronotires were collected in two sites in the Shala quarry. Stepwise thermal demagnetization (≤ 20 steps, up to 600 C) and stepwise AF demagnetization were done. To monitor possible mineralogical changes during thermal cleaning, magnetic susceptibility was measured after each heating step. Intensive rock magnetic investigations and thermal palaeointensity experiments using the Thellier-Coe (with check-points) and Wilson procedures were carried out. Electronic microscopy study of two samples was made too. For the exception of a viscous component some specimens from the contact zone of the gabbronorite dyke with thin dolerite dyke show two distinct components. The first E-NE intermediate-down direction component was separated at fields up to 50-60 mT and unblocking temperatures up to 520-540 C. The other S-SE low-down direction component is separated at fields from 60 to 100 mT and unblocking temperatures from 540 to 590-600 C. Based on the positive contact tests for the gabbronorite dyke, the S-SE shallow inclination remanence (I = -5.7 degrees) is interpreted to be of primary origin. Reliable palaeointensity determinations Banc fitting a set of selection criteria were determined on 13 samples from 2 sites carrying well-identified S-SE high-temperature components. Mean values of Banc = 49 µT and 48 µT by the Thellier-Coe and Wilson procedures, correspondingly with mean VDM = 12.6x10^22 Am2 what considerably exceeds modern VDM = 7.8x10^22 Am^2). Our finding is in line with the previously reported high VDM  8.4x10^22 Am2 determined on the same Karelian craton for the Burakovka intrusion from mafic dikes of very close age 2450 Ma (Tarduno et al., 2003) thus supporting the idea of high Paleoproterozoic/NeoAchaean geomagnetic field intensity suggested by Tarduno et al. (2006) and Biggin et al. (2009).
Rock magnetic and geochemical evidence for authigenic magnetite formation via iron reduction in coal-bearing sediments offshore Shimokita Peninsula, Japan (IODP Site C0020)

NASA Astrophysics Data System (ADS)

Phillips, Stephen C.; Johnson, Joel E.; Clyde, William C.; Setera, Jacob B.; Maxbauer, Daniel P.; Severmann, Silke; Riedinger, Natascha

2017-06-01

Sediments recovered at Integrated Ocean Drilling Program (IODP) Site C0020, in a fore-arc basin offshore Shimokita Peninsula, Japan, include numerous coal beds (0.3-7 m thick) that are associated with a transition from a terrestrial to marine depositional environment. Within the primary coal-bearing unit (˜2 km depth below seafloor) there are sharp increases in magnetic susceptibility in close proximity to the coal beds, superimposed on a background of consistently low magnetic susceptibility throughout the remainder of the recovered stratigraphic sequence. We investigate the source of the magnetic susceptibility variability and characterize the dominant magnetic assemblage throughout the entire cored record, using isothermal remanent magnetization (IRM), thermal demagnetization, anhysteretic remanent magnetization (ARM), iron speciation, and iron isotopes. Magnetic mineral assemblages in all samples are dominated by very low-coercivity minerals with unblocking temperatures between 350 and 580°C that are interpreted to be magnetite. Samples with lower unblocking temperatures (300-400°C), higher ARM, higher-frequency dependence, and isotopically heavy δ56Fe across a range of lithologies in the coal-bearing unit (between 1925 and 1995 mbsf) indicate the presence of fine-grained authigenic magnetite. We suggest that iron-reducing bacteria facilitated the production of fine-grained magnetite within the coal-bearing unit during burial and interaction with pore waters. The coal/peat acted as a source of electron donors during burial, mediated by humic acids, to supply iron-reducing bacteria in the surrounding siliciclastic sediments. These results indicate that coal-bearing sediments may play an important role in iron cycling in subsiding peat environments and if buried deeply through time, within the subsequent deep biosphere.
Medial Orbitofrontal Neurons Preferentially Signal Cues Predicting Changes in Reward during Unblocking

PubMed Central

Lopatina, Nina; McDannald, Michael A.; Styer, Clay V.; Peterson, Jacob F.; Sadacca, Brian F.; Cheer, Joseph F.

2016-01-01

The orbitofrontal cortex (OFC) has been broadly implicated in the ability to use the current value of expected outcomes to guide behavior. Although value correlates have been prominently reported in lateral OFC, they are more often associated with more medial areas. Further, recent studies in primates have suggested a dissociation in which the lateral OFC is involved in credit assignment and representation of reward identity and more medial areas are critical to representing value. Previously, we used unblocking to test more specifically what information about outcomes is represented by OFC neurons in rats; consistent with the proposed dichotomy between the lateral and medial OFC, we found relatively little linear value coding in the lateral OFC (Lopatina et al., 2015). Here we have repeated this experiment, recording in the medial OFC, to test whether such value signals might be found there. Neurons were recorded in an unblocking task as rats learned about cues that signaled either more, less, or the same amount of reward. We found that medial OFC neurons acquired responses to these cues; however, these responses did not signal different reward values across cues. Surprisingly, we found that cells developed responses to cues predicting a change, particularly a decrease, in reward value. This is consistent with a special role for medial OFC in representing current value to support devaluation/revaluation sensitive changes in behavior. SIGNIFICANCE STATEMENT This study uniquely examines encoding in rodent mOFC at the single-unit level in response to cues that predict more, less, or no change in reward in rats during training in a Pavlovian unblocking task, finding more cells responding to change-predictive cues and stronger activity in response to cues predictive of less reward. PMID:27511013
Effects of titanomagnetite reordering processes on thermal demagnetization and paleointensity experiments

NASA Astrophysics Data System (ADS)

Bowles, Julie A.; Jackson, Mike J.

2016-12-01

Titanomagnetite (Fe3-xTixO4, 0 ≤ x ≤ 1) is a common, naturally occurring magnetic mineral critical to many paleomagnetic studies. Underlying most interpretations is the assumption that, lacking chemical alteration, Curie temperature (Tc) remains constant. However, recent work has demonstrated that Tc of many natural titanomagnetites varies strongly as a function of thermal history, independent of chemical alteration. This is inferred to arise from reordering of cations and/or vacancies in the crystal structure, and changes occur at temperatures and times relevant to standard paleomagnetic thermal treatments. Because changes take place at T < Tc, they have the potential to dramatically affect thermal remanence acquisition or demagnetization, impacting interpretation of paleomagnetic results. Here we have modeled the effects of reordering on standard thermal demagnetization and paleointensity experiments. Results suggest that Tc changes during laboratory heating make it impossible to accurately measure the unblocking temperature spectrum without modifying it. Samples with a starting Tc0 less than the closure temperature (Tclose) for the reordering process will develop a high-temperature "tail" that did not exist prior to heating. Samples with a starting Tc0 > Tclose will have their original Tb spectrum truncated at T ≈ Tclose. Predicted behavior during Thellier-type paleointensity experiments results in only modest deviations in NRM-lost or pTRM*-gained from the nonreordering case. Much larger deviations are predicted for pTRM checks. Compared to paleointensity results from titanomagnetite-bearing pyroclastic deposits, modeled nonideal behavior occurs in the same temperature intervals, but is much more systematic. Reordering is likely one contributing factor to failure of paleointensity experiments.
Observing thermomagnetic stability of nonideal magnetite particles: Good paleomagnetic recorders?

NASA Astrophysics Data System (ADS)

Almeida, Trevor P.; Kasama, Takeshi; Muxworthy, Adrian R.; Williams, Wyn; Nagy, Lesleis; Dunin-Borkowski, Rafal E.

2014-10-01

The thermomagnetic behavior of remanence-induced magnetite (Fe3O4) particles in the pseudo-single-domain (PSD) size range (~0.1-10 µm), which dominate the magnetic signature of many rock lithologies, is investigated using off-axis electron holography. Construction of magnetic induction maps allowed for the visualization of the vortex domain state in an individual Fe3O4 grain (~200 nm in diameter) as a function of temperature. Acquisition of a series of electron holograms at 100°C intervals during in situ heating up to 700°C demonstrates the vortex state of the Fe3O4 grain, in this instance, remains thermally stable close to its unblocking temperature and exhibits a similar in-plane remanent state upon cooling; i.e., the particle is effectively behaving like a uniaxial single-domain particle to temperatures near TC. Such particles are thought to be robust magnetic recorders. It is suggested that evidence for PSD behavior should therefore not preclude paleomagnetic investigation.
Insights on the injection mechanisms inferred from AMS fabrics of sand injectites in a turbiditic system, the exemple of Bevon area of the SE Basin (France).

NASA Astrophysics Data System (ADS)

Robion, Philippe; Mehl, Caroline

2016-04-01

We propose to investigate the set up mechanisms of sands injection in the case of dykes injected in host marls of Aptian-Albian age in the Vocontian basin (SE France). Several models have been proposed for a downward injection of the dyke in the Bevons area and we guess that AMS fabric investigations can be used to infer the flow direction. 144 drill cores distributed on 14 sites were sampled, among which 8 sites in the injectites and 6 sites in the host rocks. The studied dykes are generally of a few decimeters thick and are setting up in both in vertical or oblique position with respect to the subhorizontal bedding of the host rocks. There were sampled from one side to the other in order to track the flow direction by identification of imbricated fabric. Magnetic mineralogy, i.e. unblocking temperature inferred from IRM 3 axes demagnetization, indicates that the ferromagnetics s.l. mineralogy is dominated by an assemblage of magnetite (unblocking temperature Tub=580°C) and pyrrhotite (Tub=325°C). Magnetic susceptibility is low, typical for siliciclastic rocks, ranging from 4x10-5 up to 1.7x10-4 SI. Degree of magnetic anisotropy is likely representative of AMS measurements in sedimentary rocks with weak values, below than 5 %. In marly host rocks magnetic mineralogy is dominated by pyrrhotite associated with magnetite and both the magnetic susceptibility and degree of anisotropy are slightly lower than for injectites. Regarding magnetic fabric axes distribution, despite some dispersion, the results show that minimum axes of AMS (K3) are parallel to the dyke plane, and maximum axes (K1) are roughly in horizontal position. In marly host rocks, the magnetic fabric is related to tectonic shortening. We interpret that the host rocks have recorded the regional tectonic imprint while the magnetic fabric of the injectites are related to early sedimentary processes. The mechanism of set up proposed to explain the magnetic fabric in the Bevon injectites is a step-by-step process of filling the pre-existing fractures with highly fluidized sand and a compaction direction parallel to dyke plane. A late diagenetic cementation affecting the injectites network prevents any further deformation during tectonic inversion.
Characterization of orogenic remagnetizations within various fold geometries in Carboniferous carbonates from thin skinned fold and thrust belts, SW Alberta and NW Montana

NASA Astrophysics Data System (ADS)

Zechmeister, M. S.; Elmore, R. D.; Ferre, E. C.; Pannalal, S. J.; Hamilton, E. M.

2007-12-01

Paleomagnetic and rock magnetic analysis was conducted on a complex fault propagation fold train in Kananaskis Country, Alberta to compliment an ongoing study of orogenic remagnetiztions in the thin-skinned, fold and thrust belt (NW Montana and SW Alberta). The complex structure is composed of an asymmetrical anticline to the west and chevron syncline to the east, with both folds plunging ~15° to the south. The fold train contains a magnetization with two stable ancient components. The characteristic remanent magnetization (ChRM) with northerly declinations and steep down inclinations is removed between ~350°C and the maximum unblocking temperature of 540°C. Tilt tests on the preliminary data reveal that the ChRM is early syntilting in the anticline and syntilting in the syncline. These results from this fold train are similar to a previous study in the Sawtooths (NW MT) which reported that fault propagation folds have a syntilting ChRM whereas fault bend folds contain a pretilting ChRM. An intermediate temperature reversed component is unblocked by 340°C and is late syntilting to post-tilting. Preliminary high-field rock magnetic data from folds in Montana and Alberta show that saturation is reached before 0.3T and the majority of the samples have wasp-waisted hysteresis loops. On a log plot of Mrs/Ms versus Hcr/Hc, the data has a power law distribution that is similar to trends reported by other authors. Interestingly though, samples from a fault bend fold have higher Mrs/Ms ratios than those measured in fault propagation folds, suggesting that strain induced by the various folding styles may influence the rock magnetic properties. Additional studies are underway to test these preliminary results and determine if the differences in the hysteresis ratios are significant. Petrographic analysis shows magnetite replacing pyrite in some samples suggesting an authigenic origin for the ChRM. The intensity of the ChRM as well as the strongest rock magnetic signal is most common in dark gray carbonates that are hydrocarbon reservoirs in the subsurface, suggesting the possibility that the origin of the ChRM may be related to hydrocarbon migration.
Stress and aversive learning in a wild vertebrate: the role of corticosterone in mediating escape from a novel stressor.

PubMed

Thaker, Maria; Vanak, Abi T; Lima, Steven L; Hews, Diana K

2010-01-01

Elevated plasma corticosterone during stressful events is linked to rapid changes in behavior in vertebrates and can mediate learning and memory consolidation. We tested the importance of acute corticosterone elevation in aversive learning of a novel stressor by wild male eastern fence lizards (Sceloporus undulatus). We found that inhibiting corticosterone elevation (using metyrapone, a corticosterone synthesis blocker) during an encounter with a novel attacker impaired immediate escape responses and limited learning and recall during future encounters. In the wild and in outdoor enclosures, lizards whose acute corticosterone response was blocked by an earlier metyrapone injection did not alter their escape behavior during repeated encounters with the attacker. Control-injected (unblocked) lizards, however, progressively increased flight initiation distance and decreased hiding duration during subsequent encounters. Aversive responses were also initially higher for control lizards exposed to a higher intensity first attack. Further, we demonstrate a role of corticosterone elevation in recollection, since unblocked lizards had heightened antipredator responses 24-28 h later. Exogenously restoring corticosterone levels in metyrapone-injected lizards maintained aversive behaviors and learning at control (unblocked) levels. We suggest that the corticosterone mediation of antipredator behaviors and aversive learning is a critical and general mechanism for the behavioral flexibility of vertebrate prey.
Coded diffraction system in X-ray crystallography using a boolean phase coded aperture approximation

NASA Astrophysics Data System (ADS)

Pinilla, Samuel; Poveda, Juan; Arguello, Henry

2018-03-01

Phase retrieval is a problem present in many applications such as optics, astronomical imaging, computational biology and X-ray crystallography. Recent work has shown that the phase can be better recovered when the acquisition architecture includes a coded aperture, which modulates the signal before diffraction, such that the underlying signal is recovered from coded diffraction patterns. Moreover, this type of modulation effect, before the diffraction operation, can be obtained using a phase coded aperture, just after the sample under study. However, a practical implementation of a phase coded aperture in an X-ray application is not feasible, because it is computationally modeled as a matrix with complex entries which requires changing the phase of the diffracted beams. In fact, changing the phase implies finding a material that allows to deviate the direction of an X-ray beam, which can considerably increase the implementation costs. Hence, this paper describes a low cost coded X-ray diffraction system based on block-unblock coded apertures that enables phase reconstruction. The proposed system approximates the phase coded aperture with a block-unblock coded aperture by using the detour-phase method. Moreover, the SAXS/WAXS X-ray crystallography software was used to simulate the diffraction patterns of a real crystal structure called Rhombic Dodecahedron. Additionally, several simulations were carried out to analyze the performance of block-unblock approximations in recovering the phase, using the simulated diffraction patterns. Furthermore, the quality of the reconstructions was measured in terms of the Peak Signal to Noise Ratio (PSNR). Results show that the performance of the block-unblock phase coded apertures approximation decreases at most 12.5% compared with the phase coded apertures. Moreover, the quality of the reconstructions using the boolean approximations is up to 2.5 dB of PSNR less with respect to the phase coded aperture reconstructions.
Time-Resolved Nucleic Acid Hybridization Beacons Utilizing Unimolecular and Toehold-Mediated Strand Displacement Designs.

PubMed

Massey, Melissa; Ancona, Mario G; Medintz, Igor L; Algar, W Russ

2015-12-01

Nucleic acid hybridization probes are sought after for numerous assay and imaging applications. These probes are often limited by the properties of fluorescent dyes, prompting the development of new probes where dyes are paired with novel or nontraditional luminescent materials. Luminescent terbium complexes are an example of such a material, and these complexes offer several unique spectroscopic advantages. Here, we demonstrate two nonstem-loop designs for light-up nucleic acid hybridization beacons that utilize time-resolved Förster resonance energy transfer (TR-FRET) between a luminescent Lumi4-Tb cryptate (Tb) donor and a fluorescent reporter dye, where time-resolved emission from the dye provides an analytical signal. Both designs are based on probe oligonucleotides that are labeled at their opposite termini with Tb and a fluorescent reporter dye. In one design, a probe is partially blocked with a quencher dye-labeled oligonucleotide, and target hybridization is signaled through toehold-mediated strand displacement and loss of a competitive FRET pathway. In the other design, the intrinsic folding properties of an unblocked probe are utilized in combination with a temporal mechanism for signaling target hybridization. This temporal mechanism is based on a recently elucidated "sweet spot" for TR-FRET measurements and exploits distance control over FRET efficiencies to shift the Tb lifetime within or outside the time-gated detection window for measurements. Both the blocked and unblocked beacons offer nanomolar (femtomole) detection limits, response times on the order of minutes, multiplexing through the use of different reporter dyes, and detection in complex matrices such as serum and blood. The blocked beacons offer better mismatch selectivity, whereas the unblocked beacons are simpler in design. The temporal mechanism of signaling utilized with the unblocked beacons also plays a significant role with the blocked beacons and represents a new and effective strategy for developing FRET probes for bioassays.
DMD-based implementation of patterned optical filter arrays for compressive spectral imaging.

PubMed

Rueda, Hoover; Arguello, Henry; Arce, Gonzalo R

2015-01-01

Compressive spectral imaging (CSI) captures multispectral imagery using fewer measurements than those required by traditional Shannon-Nyquist theory-based sensing procedures. CSI systems acquire coded and dispersed random projections of the scene rather than direct measurements of the voxels. To date, the coding procedure in CSI has been realized through the use of block-unblock coded apertures (CAs), commonly implemented as chrome-on-quartz photomasks. These apertures block or permit us to pass the entire spectrum from the scene at given spatial locations, thus modulating the spatial characteristics of the scene. This paper extends the framework of CSI by replacing the traditional block-unblock photomasks by patterned optical filter arrays, referred to as colored coded apertures (CCAs). These, in turn, allow the source to be modulated not only spatially but spectrally as well, entailing more powerful coding strategies. The proposed CCAs are synthesized through linear combinations of low-pass, high-pass, and bandpass filters, paired with binary pattern ensembles realized by a digital micromirror device. The optical forward model of the proposed CSI architecture is presented along with a proof-of-concept implementation, which achieves noticeable improvements in the quality of the reconstruction.
Decentralized semi-active damping of free structural vibrations by means of structural nodes with an on/off ability to transmit moments

NASA Astrophysics Data System (ADS)

Poplawski, Blazej; Mikułowski, Grzegorz; Mróz, Arkadiusz; Jankowski, Łukasz

2018-02-01

This paper proposes, tests numerically and verifies experimentally a decentralized control algorithm with local feedback for semi-active mitigation of free vibrations in frame structures. The algorithm aims at transferring the vibration energy of low-order, lightly-damped structural modes into high-frequency modes of vibration, where it is quickly damped by natural mechanisms of material damping. Such an approach to mitigation of vibrations, known as the prestress-accumulation release (PAR) strategy, has been earlier applied only in global control schemes to the fundamental vibration mode of a cantilever beam. In contrast, the decentralization and local feedback allows the approach proposed here to be applied to more complex frame structures and vibration patterns, where the global control ceases to be intuitively obvious. The actuators (truss-frame nodes with controllable ability to transmit moments) are essentially unblockable hinges that become unblocked only for very short time periods in order to trigger local modal transfer of energy. The paper proposes a computationally simple model of the controllable nodes, specifies the control performance measure, yields basic characteristics of the optimum control, proposes the control algorithm and then tests it in numerical and experimental examples.
A New Look at the Magnetostratigraphy and Paleomagnetism of the Upper Triassic to Lower Jurassic Moenave Formation, St. George Area, Southwestern Utah.

NASA Astrophysics Data System (ADS)

Donohoo-Hurley, L. L.; Geissman, J. W.; Lucas, S. G.; Roy, M.

2006-12-01

Paleomagnetic data from rocks exposed on and off the Colorado Plateau provide poles that young westward during the Late Triassic (to about 52^{O} E longitude) and young eastward during the Early Jurassic. This pattern has been used to posit the existence of a J-1 cusp in the North American APW path at the Triassic- Jurassic boundary (TJB), at about 199.6 Ma. Considerable debate has focused on the morphology and placement of the J-1 cusp due to poorly exposed and/or incompletely sampled sections, debates about the magnitude of Colorado Plateau rotation, and disagreements regarding stratigraphic relationships. Red beds of the Whitmore Point (~25 m of mostly lacustrine deposits) and Dinosaur Canyon (~55 m of hematitic fluvial sandstones and siltstones) members of the Moenave Formation (MF) are inferred to have been deposited across the TJB based on palynostratigraphy and vertebrate biostratigraphy. Two previously unsampled sections (Leeds and Warner Valley) of the MF are well exposed near St. George, Utah, and located in the transition zone that defines the western boundary of the Colorado Plateau. Preliminary data from samples collected from the Whitmore Point and Dinosaur Canyon members yield exclusively normal polarity magnetizations, which is consistent with previous studies and the normal polarity TJB magnetozone. Thermal demagnetization response suggests that the remanence is carried mainly in hematite. The degree of hematite pigmentation varies in both sections, and several Leeds sites show a weak overprint component that unblocks by 400^{O}-450^{O} C, with a higher unblocking temperature components, consistent with an Early Triassic Late Jurassic age that fully unblock around 670^{O}-680^{O} C. Individual beds (treated as specific sites) in part of the Dinosaur Canyon Member yield site mean directions with declinations between about 020 and 030, and may define the easternmost position (i.e. 60-50^{O} E latitude) of the NAMAPW path and thus the approximate the TJB. This interpretation is consistent with recent biostratigraphic arguments that the TJB lies in the upper part of the Dinosaur Canyon Member. The Whitmore Point Member yields more north-directed declinations, suggesting an earliest Jurassic (post-cusp) age. It is likely that more complete data from these and related sections will provide a further refinement of the stratigraphic placement of the TJB and the geometry of the J-1 cusp.
Investigating the impact of atmospheric blocking on temperature extremes across Europe using an objective index

NASA Astrophysics Data System (ADS)

Brunner, Lukas; Steiner, Andrea; Sillmann, Jana

2017-04-01

Atmospheric blocking is a key contributor to European temperature extremes. It leads to stable, long-lasting weather patterns, which favor the development of cold and warm spells. The link between blocking and such temperature extremes differs significantly across Europe. In northern Europe a majority of warm spells are connected to blocking, while cold spells are suppressed during blocked conditions. In southern Europe the opposite picture arises with most cold spells occurring during blocking and warm spells suppressed. Building on earlier work by Brunner et al. (2017) this study aims at a better understanding of the connection between blocking and temperature extremes in Europe. We investigate cold and warm spells with and without blocking in observations from the European daily high-resolution gridded dataset (E-OBS) from 1979 to 2015. We use an objective extreme index (Russo et al. 2015) to identify and compare cold and warm spells across Europe. Our work is lead by the main question: Are cold/warm spells coinciding with blocking different from cold/warm spells during unblocked conditions in regard to duration, extend, or amplitude? Here we present our research question and the study setup, and show first results of our analysis on European temperature extremes. Brunner, L., G. Hegerl, and A. Steiner (2017): Connecting Atmospheric Blocking to European Temperature Extremes in Spring. J. Climate, 30, 585-594, doi: 10.1175/JCLI-D-16-0518.1. Russo, S., J. Sillmann, and E. M. Fischer (2015): Top ten European heatwaves since 1950 and their occurrence in the coming decades. Environ. Res. Lett. 10.12, S. 124003. doi: 10.1088/1748-9326/10/12/124003.
Rapid incorporation kinetics and improved fidelity of a novel class of 3'-OH unblocked reversible terminators.

PubMed

Gardner, Andrew F; Wang, Jinchun; Wu, Weidong; Karouby, Jennifer; Li, Hong; Stupi, Brian P; Jack, William E; Hersh, Megan N; Metzker, Michael L

2012-08-01

Recent developments of unique nucleotide probes have expanded our understanding of DNA polymerase function, providing many benefits to techniques involving next-generation sequencing (NGS) technologies. The cyclic reversible termination (CRT) method depends on efficient base-selective incorporation of reversible terminators by DNA polymerases. Most terminators are designed with 3'-O-blocking groups but are incorporated with low efficiency and fidelity. We have developed a novel class of 3'-OH unblocked nucleotides, called Lightning Terminators™, which have a terminating 2-nitrobenzyl moiety attached to hydroxymethylated nucleobases. A key structural feature of this photocleavable group displays a 'molecular tuning' effect with respect to single-base termination and improved nucleotide fidelity. Using Therminator DNA polymerase, we demonstrate that these 3'-OH unblocked terminators exhibit superior enzymatic performance compared to two other reversible terminators, 3'-O-amino-TTP and 3'-O-azidomethyl-TTP. Lightning Terminators show maximum incorporation rates (k(pol)) that range from 35 to 45 nt/s, comparable to the fastest NGS chemistries, yet with catalytic efficiencies (k(pol)/K(D)) comparable to natural nucleotides. Pre-steady-state kinetic studies of thymidine analogs revealed that the major determinant for improved nucleotide selectivity is a significant reduction in k(pol) by >1000-fold over TTP misincorporation. These studies highlight the importance of structure-function relationships of modified nucleotides in dictating polymerase performance.

31 CFR 586.520 - Unblocking of previously blocked property.

Code of Federal Regulations, 2010 CFR

2010-07-01

... (SERBIA & MONTENEGRO) KOSOVO SANCTIONS REGULATIONS Licenses, Authorizations, and Statements of Licensing... (Serbia & Montenegro) Milosevic Regulations set forth at 31 CFR part 587 or the Western Balkans...
Performance and Near-Wake Flow field of A Marine Hydrokinetic Turbine Operating in Free surface Proximity

NASA Astrophysics Data System (ADS)

Banerjee, Arindam; Kolekar, Nitin

2015-11-01

The current experimental investigation aims at understanding the effect of free surface proximity and associated blockage on near-wake flow-field and performance of a three bladed horizontal axis marine hydrokinetic turbine. Experiments were conducted on a 0.14m radius, three bladed constant chord turbine in a 0.61m ×0.61m test section water channel. The turbine was subjected to various rotational speeds, flow speeds and depths of immersion. Experimental data was acquired through a submerged in-line thrust-torque sensor that was corrected to an unblocked dataset with a blockage correction using measured thrust data. A detailed comparison is presented between blocked and unblocked datasets to identify influence of Reynolds number and free surface proximity on blockage effects. The percent change in Cp was found to be dependent on flow velocity, rotational speed and free surface to blade tip clearance. Further, flow visualization using a stereoscopic particle image velocimetry was carried out in the near-wake region of turbine to understand the mechanism responsible for variation of Cp with rotational speed and free surface proximity. Results revealed presence of slower wake at higher rotational velocities and increased asymmetry in the wake at high free surface proximity.
Testing paleointensity determinations on recent lava flows and scorias from Miyakejima, Japan

NASA Astrophysics Data System (ADS)

Fukuma, K.

2013-12-01

Still no consensus has been reached on paleointensity method. Even the classical Thellier method has not been fully tested on recent lava flows with known geomagnetic field intensity based on a systematic sampling scheme. In this study, Thellier method was applied for 1983, 1962 and 1940 basaltic lava flows and scorias from Miyakejima, Japan. Several vertical lava sections and quenched scorias, which are quite variable in magnetic mineralogy and grain size, provide an unparalleled opportunity to test paleointensity methods. Thellier experiments were conducted on a completely automated three-component spinner magnetometer with thermal demagnetizer 'tspin'. Specimens were heated in air, applied laboratory field was 45 microT, and pTRM checks were performed at every two heating steps. Curie points and hysteresis properties were obtained on small fragments removed from cylindrical specimens. For lava flows sigmoidal curves were commonly observed on the Arai diagrams. Especially the interior part of lava flows always revealed sigmoidal patterns and sometimes resulted in erroneously blurred behaviors. The directions after zero-field heating were not necessarily stable in the course of the Thellier experiments. It was very difficult, for the interior part, to ascertain linear segments on Arai diagrams corresponding to the geomagnetic field intensity at the eruption. Upper and lower clinker samples also generally revealed sigmoidal or upward concave curves on Arai diagrams. Neither lower nor higher temperature portions of the sigmoids or concaves gave the expected geomagnetic field intensities. However, there were two exceptional cases of lava flows giving correct field intensities: upper clinkers with relatively low unblocking temperatures (< 400 deg.C) and lower clinkers with broad unblocking temperature ranges from room temperature to 600 deg.C. A most promising target for paleointensity experiments within the volcanic rocks is scoria. Scoria samples always carry single Curie temperatures higher than 500 deg.C, and the ratios of saturation remanence to saturation magnetization (Mr/Ms) of about 0.5 are indicative of truly single-domain low-titanium titanomagnetite. Unambiguous straight lines were always observed on Arai diagrams covering broad temperature ranges like the lower clinker samples, and the gradients gave the expected field values within a few percent errors. Thellier experiments applied for the recent lava flows did not successfully recover the expected field intensity from most samples. No linear segment was recognized or incorrect paleointensity values were obtained from short segments with limited temperature ranges. In Thellier or other types of paleointensity experiments laboratory alteration is checked in details, but if a sample once passed the alteration check, the TRM/NRM ratios of any limited temperature or field ranges were accepted as reflecting paleointensity. Previously published paleointensity data from lava flows should include much of such dubious data. Generally lava flows are not suitable for paleointensity determinations in light of its large grain-size and mixed magnetic mineralogy, except for scoria and clinker.
Paleomagnetism of Jurassic-Cretaceous basalts from the Franz Josef Land Archipelago: tectonic implications

NASA Astrophysics Data System (ADS)

Abashev, Victor; Mikhaltsov, Nikolay; Vernikovsky, Valery

2015-04-01

New paleomagnetic data were obtained from a total of 158 oriented samples collected from the Jurassic magmatic complexes exposed on the Franz Joseph Land Archipelago (FJL). The field work was conducted during 2011 field season. Present study was focused on the tholeiitic basaltic lava flows that crop out on the Hooker Island. The samples were subjected to a detailed step-wise thermal demagnetization in temperatures up to 600 deg C or alternating field demagnetization with maximum filed up to 140 mT. Natural remanent magnetization (NRM) was measured with a 2G cryogenic magnetometer or a JR-6A spin-magnetometer housed in a magnetically shielded room at the Institute of Petroleum Geology and Geophysics, Siberian Branch of Russian Academy of Sciences. The main NRM carriers in the FJL samples are titanomagnetites with varying Ti-content. Magnetic remanence was unblocked in temperatures of 350-400 deg C. Some samples are characterized by unblocking temperatures of 560 deg C. The new paleomagnetic data were combined with those previously obtained from the early Cretaceous volcanics exposed on the FJL. A new mean paleomagnetic direction for the Jurassic rocks was calculated as D=78.3 deg, I=74.7 deg, a95=3.1 deg, k=194.3, N=13. A corresponding paleomagnetic pole is now located at Plat=62.1 deg; Plon=136.5 deg, A95=5.5 deg, K=63.6. New results suggest that the JFL occupied a significantly different position from that of the present day. However, in early Cretaceous the JFL was already located close to its present day position. We propose a rifting event between the North Barentz terrane (FJL and possibly Svalbard) and the counterpart of European tectonic domain. The rifting occurred during Early-Middle Jurassic. This event was accompanied by a significant shift of the FJL to the north-east for approximately 500 km. New results are in good agreement with a hypothesis that the FJL was passing over the Icelandic-Siberian hot spot during the Jurassic-Cretaceous time. Paleolatitudes for the Hooker Island correspond to its present latitude and the paleolatitude of the Siberian trapps. The reported results are preliminary and cannot lead to any ultimate interpretation. Further investigations are needed. This and future studies are supported by the Russian Foundation for Basic Research grant 13-05-00177 and Russian Science Foundation grant 14-37-00030.
75 FR 12000 - Unblocking of Specially Designated Nationals and Blocked Persons

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Prior exposure to a reverberant listening environment improves speech intelligibility in adult cochlear implant listeners.

PubMed

Srinivasan, Nirmal Kumar; Tobey, Emily A; Loizou, Philipos C

2016-01-01

The goal of this study is to investigate whether prior exposure to reverberant listening environment improves speech intelligibility of adult cochlear implant (CI) users. Six adult CI users participated in this study. Speech intelligibility was measured in five different simulated reverberant listening environments with two different speech corpuses. Within each listening environment, prior exposure was varied by either having the same environment across all trials (blocked presentation) or having different environment from trial to trial (unblocked). Speech intelligibility decreased as reverberation time increased. Although substantial individual variability was observed, all CI listeners showed an increase in the blocked presentation condition as compared to the unblocked presentation condition for both speech corpuses. Prior listening exposure to a reverberant listening environment improves speech intelligibility in adult CI listeners. Further research is required to understand the underlying mechanism of adaptation to listening environment.
Comments on shielding for dual energy accelerators.

PubMed

Rossi, M C; Lincoln, H M; Quarin, D J; Zwicker, R D

2008-06-01

Determination of shielding requirements for medical linear accelerators has been greatly facilitated by the publication of the National Council on Radiation Protection and Measurements (NCRP) latest guidelines on this subject in NCRP Report No. 151. In the present report the authors review their own recent experience with patient treatments on conventional dual energy linear accelerators to examine the various input parameters needed to follow the NCRP guidelines. Some discussion is included of workloads, occupancy, use factors, and field size, with the effects of intensity modulated radiotherapy (IMRT) treatments included. Studies of collimator settings showed average values of 13.1 x 16.2 cm2 for 6 MV and 14.1 x 16.8 cm2 for 18 MV conventional ports, and corresponding average unblocked areas of 228 and 254 cm2, respectively. With an average of 77% of the field area unblocked, this gives a mean irradiated area of 196 cm2 for the 18 MV beam, which dominates shielding considerations for most dual energy machines. Assuming conservatively small room dimensions, a gantry bin angle of 18 degrees was found to represent a reasonable unit for tabulation of use factors. For conventional 18 MV treatments it was found that the usual treatment angles of 0, 90, 180, and 270 degrees were still favored, and use factors of 0.25 represent reasonable estimates for these beams. As expected, the IMRT fields (all at 6 MV) showed a high degree of gantry angle randomization, with no bin having a use factor in excess of 0.10. It is concluded that unless a significant number of patients are treated with high energy IMRT, the traditional use factors of 0.25 are appropriate for the dominant high energy beam.
77 FR 25234 - Unblocking of One Individual Specially Designated Global Terrorist Pursuant to Executive Order 13224

Federal Register 2010, 2011, 2012, 2013, 2014

2012-04-27

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2011-03-25

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.... ``ABU SA'AD''; a.k.a. ``ABU SAAD''; a.k.a. ``FREEDOM FIGHTER''); DOB 17 Feb 1971; POB Madiun, East Java..., Lamongan district, East Java province, Indonesian; nationality Indonesia (individual) [SDGT]. SAMUDRA, Imam...
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2013-01-29

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Federal Register 2010, 2011, 2012, 2013, 2014

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2012-10-02

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76 FR 63352 - Office of Foreign Assets Control

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2011-10-12

... DEPARTMENT OF THE TREASURY Office of Foreign Assets Control Unblocking of Three Specially Designated Nationals Pursuant to Executive Order 13224 AGENCY: Office of Foreign Assets Control, Treasury. ACTION: Notice. SUMMARY: The Treasury Department's Office of Foreign Assets Control (``OFAC'') is...
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... Order: 1. FAVARONY URREA, Pedro F., c/o COPSERVIR LTDA., Bogota, Colombia; Cedula No. 167136671...) (individual) [SDNT]. 10. GARCIA DUQUE, Gustavo, Carrera 4 No. 12-20 of. 206, Cartago, Valle, Colombia; c/o...
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2012-03-12

..., Orlando, c/o ALFA PHARMA S.A., Bogota, Colombia; c/o LABORATORIOS GENERICOS VETERINARIOS, Bogota, Colombia.../o DISTRIBUIDORA DE DROGAS CONDOR LTDA., Bogota, Colombia; c/o ALFA PHARMA S.A., Bogota, Colombia; c...
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2011-05-04

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2012-09-06

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2010-07-22

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2010-06-16

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2011-03-02

... PERU S.A., Lima, Peru; DOB 9 Aug 1976; D.N.I. 10006822 (Peru) (individual) [SDNT] MORALES LUYO, Luis Jaime, c/o COLFARMA PERU S.A., Lima, Peru; LE Number 08195408 (Peru) (individual) [SDNT] OTALORA...
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2010-12-20

... DEPOSITO POPULAR DE DROGAS S.A., Cali, Colombia; c/o INVERSIONES Y CONSTRUCCIONES ABC S.A., Cali, Colombia... KRESSFOR DE COLOMBIA S.A., Bogota, Colombia; c/o INVERSIONES ARA LTDA., Cali, Colombia; c/o VALORES...
Perfusion index and plethysmographic variability index in patients with interscalene nerve catheters.

PubMed

Sebastiani, Anne; Philippi, Larissa; Boehme, Stefan; Closhen, Dorothea; Schmidtmann, Irene; Scherhag, Anton; Markstaller, Klaus; Engelhard, Kristin; Pestel, Gunther

2012-12-01

Interscalene nerve blocks provide adequate analgesia, but there are no objective criteria for early assessment of correct catheter placement. In the present study, pulse oximetry technology was used to evaluate changes in the perfusion index (PI) in both blocked and unblocked arms, and changes in the plethysmographic variability index (PVI) were evaluated once mechanical ventilation was instituted. The PI and PVI values were assessed using a Radical-7™ finger pulse oximetry device (Masimo Corp., Irvine, CA, USA) in both arms of 30 orthopedic patients who received an interscalene catheter at least 25 min before induction of general anesthesia. Data were evaluated at baseline, on application of local anesthetics; five, ten, and 15 min after onset of interscalene nerve blocks; after induction of general anesthesia; before and after a 500 mL colloid fluid challenge; and five minutes thereafter. In the 25 patients with successful blocks, the difference between the PI values in the blocked arm and the PI values in the contralateral arm increased within five minutes of the application of the local anesthetics (P < 0.05) and increased progressively until 15 min. After induction of general anesthesia, the PI increased in the unblocked arm while it remained relatively constant in the blocked arm, thus reducing the difference in the PI. A fluid challenge resulted in a decrease in PVI values in both arms. The perfusion index increases after successful interscalene nerve blockade and may be used as an indicator for successful block placement in awake patients. The PVI values before and after a fluid challenge can be useful to detect changes in preload, and this can be performed in both blocked and unblocked arms.
16 CFR 1450.2 - Definitions.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 16 Commercial Practices 2 2011-01-01 2011-01-01 false Definitions. 1450.2 Section 1450.2... GRAEME BAKER POOL AND SPA SAFETY ACT REGULATIONS § 1450.2 Definitions. (a) [Reserved] (b) Unblockable... American Society of Mechanical Engineers (ASME), ATTN: Secretary, A112 Standards Committee, Three Park...
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2013-05-15

... Economic Powers Act (50 U.S.C. 1701-1706) (``IEEPA''), issued Executive Order 12978 (60 FR 54579, October... Secretary of Treasury, in consultation with the Attorney General and the Secretary of State: (a) To play a...
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2013-02-06

... Economic Powers Act (50 U.S.C. 1701-1706) (``IEEPA''), issued Executive Order 12978 (60 FR 54579, October... Secretary of Treasury, in consultation with the Attorney General and the Secretary of State: (a) To play a...
Response of the formosan subterranean termite to neighboring con-specific populations after baiting with noviflumuron

USDA-ARS?s Scientific Manuscript database

Coptotermes formosanus Shiraki are economically important subterranean termites, particularly in the Southeastern United States where they are considered invasive. Where two C. formosanus populations met, aggressive encounters resulted in blockages in tunnels, but reinvading termites unblocked obstr...

78 FR 20389 - Unblocking of Specially Designated Nationals and Blocked Persons Pursuant to Executive Order 12978

Federal Register 2010, 2011, 2012, 2013, 2014

2013-04-04

..., Colombia; c/o ACUICOLA SANTA CATALINA S.A., Bogota, Colombia; c/o PROMOCIONES E INVERSIONES LAS PALMAS S.A...) (individual) [SDNT]. 9. GARCES VARGAS, Elmo, c/o INVERSIONES BETANIA LTDA., Cali, Colombia; c/o INVERSIONES EL...
77 FR 47164 - Actions Taken Pursuant to Executive Order 13382

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2012-08-07

... DEPARTMENT OF THE TREASURY Office of Foreign Assets Control Actions Taken Pursuant to Executive Order 13382 AGENCY: Office of Foreign Assets Control, TD. ACTION: Notice. SUMMARY: The Treasury Department's Office of Foreign Assets Control (``OFAC'') is unblocking and removing three entities from OFAC...
77 FR 74916 - Unblocking of Specially Designated Nationals and Blocked Persons Pursuant to the Foreign...

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2012-12-18

... BUITRAGO, Mesias, c/o GESTION ALFA LTDA., Bogota, Colombia; Calle 62 No. 9A-82 of. 616, Bogota, Colombia.... GESTION ALFA LTDA., Calle 62 No. 9A-82 of. 810, Bogota, Colombia; NIT 830095836-9 (Colombia) [SDNTK]. In...
Physical Basis of the Thellier-Thellier Paleointensity Method and its Descendants (Invited)

NASA Astrophysics Data System (ADS)

Dunlop, D. J.

2009-12-01

Fifty years have passed since Émile and Odette Thellier proposed the method of paleointensity determination which bears their names. Although there are precursors in the work of Koenigsberger, credit for the fundamental notion of partial TRMs as building blocks for the construction and reconstruction of thermally produced remanences in nature and the laboratory is Émile Thellier’s alone. In his 1938 paper in Ann. Inst. Phys. Globe Univ. Paris - a masterpiece among doctoral theses - and in the brief notes in Comptes-Rendus Acad. Sci. Paris which preceded it, he painstakingly and minutely examined the data on TRM and partial TRM (Koenigsberger’s and others’ as well as his own), ultimately establishing - for bricks and other baked clays - what we today call the Thellier laws of pTRM reciprocity, independence and additivity. He went even further in a seldom cited 1946 paper (C.R. Acad. Sci. Paris 223, 319-321), in which he invented the concept of blocking: “…immobilization of elementary magnetic moments below a temperature Θ … The temperature Θ will vary at each point in the body, perhaps with the dimensions and the shape of the crystalline grains, and will be broadly distributed between the Curie point and room temperature. One can thus explain thermoremanence by the progressive fixing, in the course of cooling, of moments, which find themselves held fast when they pass through their individual temperature Θ.” Thellier himself thus established the physical basis of TRM blocking and moreover recognized the essential role of grain size and shape. Three years later, Louis Néel elegantly quantified these concepts as fundamental properties of single-domain grains. Today the Thelliers’ method remains the most trusted benchmark of reliable paleointensity data. Indeed, apart from a few breakaway approaches utilizing VRM (Walton), ARM and AF demagnetization (Shaw and colleagues), and pTRM production at a single temperature in a variety of fields (Dekkers and Boehnel), all methods in vogue today are variants of the original Thellier-Thellier approach. The challenge has been to detect and in fortunate cases correct for the non-idealities of real geological (and to a lesser extent, archeological) materials: TRM carriers larger than single-domain size and the inevitable physico-chemical alteration of grains of all sizes on heating. Thellier circumvented these problems by using only materials previously fired to temperatures and under conditions similar to those attained in laboratory heatings, eschewing the volcanic and other rocks used by Koenigsberger and Nagata. But despite their problems, we have to deal with the rocks nature provides. Partial TRM checks detect all but the most subtle alteration but correcting for alteration using these checks is fraught with difficulty. Tail checks detect multidomain carriers through non-reciprocity of their pTRM blocking and unblocking, although half the tails (those at the lower end of the unblocking temperature spectrum) are not detectable by current procedures. This presentation will attempt to give a theoretical/ phenomenological underpinning for these check procedures as well as for the Thellier-Thellier method itself in its various manifestations.
The neglected Indo-Gangetic Plains low-level jet and its importance for moisture transport and precipitation during the peak summer monsoon

NASA Astrophysics Data System (ADS)

Acosta, R. P.; Huber, M.

2017-08-01

Accurately simulating the Indo-Asian monsoon (IAM) using atmospheric general circulation models (AGCMs) is challenging but crucial. This study uses reanalysis products European Centre of Medium-Range Forecast Interim reanalysis, Japanese Reanalysis year 55, and High Asia Reanalysis to highlight an easterly, low-level barrier jet along the Indo-Gangetic Plain (referred from here as IG LLJ), which we identify as the primary moisture transport mechanism for the northeastern branch of the IAM. We show that the NCAR family of AGCMs (Community Atmospheric Model (CAM)) does not capture this circulation until 1/2° or greater spatial horizontal resolution is used. The IG LLJ develops due to a persistent low-pressure system centered over the Ganges basin and is enhanced by the Himalayas. Using diabatic heating rates and the moist Froude number as diagnostics, we find that in CAM, this branch of the IAM displays two different dynamical regimes as a function of resolution. At low resolution, the atmosphere near the Himalayas is statically unstable, diabatic heating is strong, and the moisture flow is southwesterly from the Arabian Sea and moves over the terrain (unblocked). At high resolution, the moist static stability near the Himalayan Mountains is stable, diabatic heating is weak, and the flow primarily enters easterly from the Bay of Bengal and moves parallel to the terrain (blocked). During the summer season, the low-resolution CAM is locked into the unblocked mode, which has serious implications for interpreting topography-monsoon interactions. For a broader context, we demonstrate that more than half of the CMIP5 models do not capture the IG LLJ, which further highlights model-data mismatch across the IAM region.
Early-phase transmission of Yersinia pestis by unblocked fleas as a mechanism explaining rapidly spreading plague epizootics.

PubMed

Eisen, Rebecca J; Bearden, Scott W; Wilder, Aryn P; Montenieri, John A; Antolin, Michael F; Gage, Kenneth L

2006-10-17

Plague is a highly virulent disease believed to have killed millions during three historic human pandemics. Worldwide, it remains a threat to humans and is a potential agent of bioterrorism. Dissemination of Yersinia pestis, the etiological agent of plague, by blocked fleas has been the accepted paradigm for flea-borne transmission. However, this mechanism, which requires a lengthy extrinsic incubation period before a short infectious window often followed by death of the flea, cannot sufficiently explain the rapid rate of spread that typifies plague epidemics and epizootics. Inconsistencies between the expected rate of spread by blocked rat fleas and that observed during the Black Death has even caused speculation that plague was not the cause of this medieval pandemic. We used the primary vector to humans in North America, Oropsylla montana, which rarely becomes blocked, as a model for studying alternative flea-borne transmission mechanisms. Our data revealed that, in contrast to the classical blocked flea model, O. montana is immediately infectious, transmits efficiently for at least 4 d postinfection (early phase) and may remain infectious for a long time because the fleas do not suffer block-induced mortality. These factors match the criteria required to drive plague epizootics as defined by recently published mathematical models. The scenario of efficient early-phase transmission by unblocked fleas described in our study calls for a paradigm shift in concepts of how Y. pestis is transmitted during rapidly spreading epizootics and epidemics, including, perhaps, the Black Death.
Synthesis and evaluations of an acid-cleavable, fluorescently labeled nucleotide as a reversible terminator for DNA sequencing.

PubMed

Tan, Lianjiang; Liu, Yazhi; Li, Xiaowei; Wu, Xin-Yan; Gong, Bing; Shen, Yu-Mei; Shao, Zhifeng

2016-02-11

An acid-cleavable linker based on a dimethylketal moiety was synthesized and used to connect a nucleotide with a fluorophore to produce a 3'-OH unblocked nucleotide analogue as an excellent reversible terminator for DNA sequencing by synthesis.
77 FR 2609 - Unblocking of Specially Designated Nationals and Blocked Persons Pursuant to the Foreign...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-01-18

..., S.A. DE C.V. (a.k.a. MEDIC EXPRESS, S.A. DE C.V.; a.k.a. GRUPO LOMEDIC), Av. del Parque 489, Col. San Andres, Guadalajara, Jalisco 44810, Mexico; Calle Chicle 234, Colonia El Colli Industrial, Zapopan...
76 FR 78082 - Unblocking of Specially Designated Nationals and Blocked Persons Pursuant to Executive Order 12978

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2011-12-15

... Oeste No. 24C-75 apt. 1501, Cali, Colombia; c/o COLOR 89.5 FM STEREO, Cali, Colombia; Carrera 76A No. 6-34 apt. 107, Cali, Colombia; DOB 23 Nov 1960; Cedula No. 16264395 (Colombia) (individual) [SDNT...
Is There a Hemingway in the House?

ERIC Educational Resources Information Center

Schmidt, Laurel

2004-01-01

Creative warm-up activities help most of the articulate students who hate writing and unblock the most reluctant writers. Some of the warm-up activities for students in elementary grades that help in taking the fright out of writing, or just reduce the initial resistance are described.
75 FR 26845 - Unblocking of Specially Designated Nationals and Blocked Persons Pursuant to Executive Order 12978

Federal Register 2010, 2011, 2012, 2013, 2014

2010-05-12

... S.A., Madrid, Spain; c/o SOCIEDAD INVERSORA EN PROYECTOS DE INTERNET S.A., Madrid, Spain; D.N.I... PROYECTOS DE INTERNET, S.A., Calle Segre 25, Madrid 28002, Spain [SDNT] Dated: May 6, 2010. Adam J. Szubin...
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2013-12-03

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77 FR 63419 - Unblocking of Specially Designated Nationals and Blocked Persons Pursuant to the Foreign...

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2012-10-16

..., Colombia; c/o COMERCIALIZADORA EL PROVEEDOR LTDA., Villavicencio, Colombia; c/o INVERSIONES BUENOS AIRES LTDA., Pereira, Colombia; c/o INVERSIONES Y DISTRIBUCIONES COLOMBIANAS EL OASIS LTDA., Villavicencio... LTDA.; Linked to: INVERSIONES BUENOS AIRES LTDA.; Linked to: INVERSIONES Y DISTRIBUCIONES COLOMBIANAS...
New paleomagnetic results from Cretaceous rocks of the Gyaring Co fault region, central Tibet

NASA Astrophysics Data System (ADS)

Finn, D.; Zhao, X.; Lippert, P. C.; Yin, A.; Li, Y.; Wang, C.; Meng, J.; Zhang, S.; Li, H.

2010-12-01

Conjugate strike-slip faults are widespread features throughout the Alpine-Himalayan collision zone. They often exhibit V-shapes in map view and trend 60-75° from the maximum compressive-stress (σ1). Andersonian fault mechanics, however, predict faults to form X-shaped at ~30° from σ1. Consequently, V-shaped conjugate faults have been thought to initiate at ~30° to σ1, and subsequently rotate into their current orientation through continued shortening. Alternatively, the Paired General Shear Zone (PGSZ) model may explain development of conjugate strike-slip faults in their modern orientations, predicting no rotation. Strike-slip faulting produces rigid-body motion and internal deformation quantifiable by paleomagnetism when integrated with structural information. We wonder if paleomagnetic studies of the fault-bounded blocks in central Tibet would allow us to differentiate the two competing models for the formation of V-shaped conjugate faults. We collected over 300 paleomagnetic samples (40 sites) from stratigraphic sections in Shengza and Nima areas of central Tibet. The rocks we collected range from Jurassic to Oligocene, and are mainly grey limestones and red sediments including siltstone, mudstone, sandstone, and conglomerate, offering opportunity of applying paleomagnetic fold and conglomerate tests to check the stability of the remanent magnetization. Up to present, useful results were obtained for 150 of the early Cretaceous limestone and sandstone samples (Langshan and Duoni formations, respectively). We have characterized the stable components of natural remanent magnetization (NRM) of these samples through detailed thermal (mainly) and alternating field (AF) demagnetization. We have also conducted rock magnetic investigation to identify the magnetic carriers in these rocks. Most limestone and red sandstones exhibit two distinctive components of magnetization. The lower unblocking-temperature component is an overprint. The higher unblocking-temperature component is the characteristic component (ChRM), is well defined in vector demagnetization plots with both normal and reversed polarities and carried by magnetite and hematite. The site-mean directions pass the local fold test at more than 95% confidence level. Our new results indicate that there has been no rotation of this region relative to Eurasia, Mongolia, and the North and South China blocks since the lower Cretaceous. Thus paleomagnetic evidence appears to favor the PGSZ model and supports geological estimates for the shortening north of the Bangong suture zone, leading to an improved tectonic interpretation of the region.
75 FR 61574 - Unblocking of Specially Designated Nationals and Blocked Persons Pursuant To the Foreign...

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2010-10-05

... & Implementation, U.S. Department of the Treasury, Office of Foreign Assets Control, Washington, DC 20220, tel... and their organizations on a worldwide basis, with the objective of denying their businesses and... the Central Intelligence Agency, the Director of the Federal Bureau of Investigation, the...
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2012-05-23

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2013-05-15

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31 CFR 587.507 - Provision of certain legal services authorized.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 31 Money and Finance: Treasury 3 2010-07-01 2010-07-01 false Provision of certain legal services authorized. 587.507 Section 587.507 Money and Finance: Treasury Regulations Relating to Money and Finance...-case basis authorizing receipt from unblocked sources of payment of professional fees and reimbursement...
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2011-09-28

...; Cedula No. 55150515 (Colombia); Passport 55150515 (Colombia) (individual) [SDNT] CREDIVIDA, Calle 16 No... (Colombia); Passport P050296 (Colombia) (individual) [SDNT] CUBILLOS, Bellanidia, c/o FARMEDIS LTDA., Bogota...., Bogota, Colombia; DOB 29 Feb 1968; Cedula No. 36378461 (Colombia); Passport 36378461 (Colombia...
77 FR 44718 - Unblocking of Specially Designated Nationals and Blocked Persons Pursuant to Executive Order 12978

Federal Register 2010, 2011, 2012, 2013, 2014

2012-07-30

...., Bogota, Colombia; DOB 07 Aug 1954; POB Cali, Colombia; Cedula No. 16585721 (Colombia); Passport AF783512 (Colombia); alt. Passport AE187469 (Colombia); alt. Passport 16585721 (Colombia) (individual) [SDNT] 4...; Cedula No. 41700627 (Colombia); Passport AH715906 (Colombia); alt. Passport AH456850 (Colombia...

31 CFR 515.546 - Accounts of Cuban sole proprietorships.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 31 Money and Finance:Treasury 3 2011-07-01 2011-07-01 false Accounts of Cuban sole proprietorships. 515.546 Section 515.546 Money and Finance: Treasury Regulations Relating to Money and Finance... proprietorships. Specific licenses are issued unblocking sole proprietorships established under the laws of Cuba...
31 CFR 515.546 - Accounts of Cuban sole proprietorships.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 31 Money and Finance: Treasury 3 2010-07-01 2010-07-01 false Accounts of Cuban sole proprietorships. 515.546 Section 515.546 Money and Finance: Treasury Regulations Relating to Money and Finance... proprietorships. Specific licenses are issued unblocking sole proprietorships established under the laws of Cuba...
31 CFR 515.546 - Accounts of Cuban sole proprietorships.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 31 Money and Finance:Treasury 3 2013-07-01 2013-07-01 false Accounts of Cuban sole proprietorships. 515.546 Section 515.546 Money and Finance: Treasury Regulations Relating to Money and Finance... proprietorships. Specific licenses are issued unblocking sole proprietorships established under the laws of Cuba...
31 CFR 515.546 - Accounts of Cuban sole proprietorships.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 31 Money and Finance:Treasury 3 2014-07-01 2014-07-01 false Accounts of Cuban sole proprietorships. 515.546 Section 515.546 Money and Finance: Treasury Regulations Relating to Money and Finance... proprietorships. Specific licenses are issued unblocking sole proprietorships established under the laws of Cuba...
77 FR 76624 - Unblocking of Specially Designated Nationals and Blocked Persons Pursuant to the Foreign...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-12-28

..., Fraccionamiento Quintas Del Sol, Chihuahua, Chihuahua, Mexico; DOB 10 Apr 1962; POB Culiacan, Sinaloa, Mexico... Sol, Chihuahua, Chihuahua, Mexico; Calle Ohio 3200, Chihuahua, Chihuahua, Mexico; DOB 19 Jan 1972; POB... Michigan, Fraccionamiento Quintas del Sol, Chihuahua, Chihuahua, Mexico; DOB 05 Oct 1966; POB Chihuahua...
31 CFR 515.557 - Accounts of Cuban partnerships.

Code of Federal Regulations, 2010 CFR

2010-07-01

... are issued unblocking partnerships established under the laws of Cuba as follows: (a) Where all of the general partners and limited partners, if any, have emigrated from Cuba and have established residence in...) Where one or more partners, whether general or limited, is still in Cuba (or elsewhere but still blocked...
31 CFR 500.558 - Accounts of blocked partnerships.

Code of Federal Regulations, 2010 CFR

2010-07-01

... are issued unblocking partnerships established under the laws of North Korea, North Viet-Nam, Cambodia..., have emigrated from North Korea, North Viet-Nam, Cambodia, or South Viet-Nam and have established... located. (b) Where one or more partners, whether general or limited, is in North Korea, North Viet-Nam...
78 FR 47489 - Unblocking of Specially Designated Nationals and Blocked Persons Pursuant to the Foreign...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-08-05

...; c/o INVERPUNTO DEL VALLE S.A., Cali, Colombia; c/o INVERSIONES CIFUENTES Y CIA. S. EN C., Medellin...: INVERPUNTO DEL VALLE S.A.; Linked To: INVERSIONES CIFUENTES Y CIA. S. EN C.; Linked To: LE CLAUDE, S.A. DE C...
Managing Time and Stress.

ERIC Educational Resources Information Center

Huffstutter, Sandra; Smith, Stuart C.

Chapter 14 of a revised volume on school leadership, this chapter offers many practical suggestions for managing time and reducing stress. The primary challenge is to unblock the route to effective time/stress management by recognizing unproductive values and attitudes (such as overreliance on the Protestant work ethic or the appearance of…
Methylation controls the low temperature induction of flowering in Arabidopsis.

PubMed

Dennis, E S; Bilodeau, P; Burn, J; Finnegan, E J; Genger, R; Helliwell, C; Kang, B J; Sheldon, C C; Peacock, W J

1998-01-01

Control of the transition to flowering is critical for reproductive success of a plant. Studies in Arabidopsis have led us to suggest how this species has harnessed the environmental cue of a period of low temperature to ensure flowering occurs at an appropriate time. We propose that Arabidopsis has both vernalization-independent and vernalization-dependent pathways for the initiation of inflorescence development in the shoot apex. The vernalization-independent pathway may be concerned with the supply of carbohydrate to the shoot apex. In late flowering ecotypes which respond to vernalization the vernalization-independent pathway is blocked by the action of two dominant repressors of flowering, FRI and FLC, which interact to produce very late flowering plants which respond strongly to vernalization. We have isolated a gene which may correspond to FLC. We suggest the vernalization-dependent pathway, which may be concerned with apical GA biosynthesis, is blocked by methylation of a gene critical for flowering. This gene may correspond to that encoding kaurenoic acid hydroxylase (KAH), an enzyme catalysing a step in the GA biosynthetic pathway. Under this scheme vernalization causes unblocking of this pathway by demethylation possibly of the KAH gene and consequent biosynthesis of active GAs in the apex.
76 FR 20452 - Unblocking of Specially Designated Nationals and Blocked Persons Pursuant to the Foreign...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-04-12

.... FOR FURTHER INFORMATION CONTACT: Assistant Director, Compliance Outreach & Implementation, U.S... their businesses and agents access to the U.S. financial system and to the benefits of trade and... Attorney General, the Director of the Central Intelligence Agency, the Director of the Federal Bureau of...
75 FR 65558 - Unblocking of Specially Designated Nationals and Blocked Persons Pursuant to the Foreign...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-10-25

..., 2010. FOR FURTHER INFORMATION CONTACT: Assistant Director, Compliance Outreach & Implementation, U.S... organizations on a worldwide basis, with the objective of denying their businesses and agents access to the U.S... Secretary of the Treasury consults with the Attorney General, the Director of the Central Intelligence...
31 CFR 515.521 - U.S. assets of certain Cuban corporations.

Code of Federal Regulations, 2011 CFR

2011-07-01

... corporations. 515.521 Section 515.521 Money and Finance: Treasury Regulations Relating to Money and Finance... corporations. (a) Specific licenses may be issued unblocking the net pro rata shares of individuals who are... designated nationals, in U.S.-located assets of corporations formed under the laws of Cuba, after deducting...
77 FR 67733 - Unblocking of One Specially Designated Terrorist Pursuant to Executive Order 12947

Federal Register 2010, 2011, 2012, 2013, 2014

2012-11-13

... Nationals and Blocked Persons (``SDN List''). DATES: The removal of this individual from the SDN List is..., tel.: 202/622-2490. SUPPLEMENTARY INFORMATION: Electronic and Facsimile Availability The SDN List and... has determined that this individual should be removed from the SDN List. The following individual is...
78 FR 26424 - Unblocking of One (1) Individual Specially Designated Global Terrorist Pursuant to Executive...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-05-06

... Designated Nationals and Blocked Persons (``SDN List''). DATES: The removal of this individual from the SDN... 20220, tel.: 202/622-2490. SUPPLEMENTARY INFORMATION: Electronic and Facsimile Availability The SDN List... determined that this individual should be removed from the SDN List. The following designation is removed...
76 FR 32266 - Unblocking of one Specially Designated National or Blocked Person Pursuant to Executive Order...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-06-03

... Executive Order 13350 of July 30, 2004. DATES: The removal of this individual from the SDN List is effective...-2490. SUPPLEMENTARY INFORMATION: Electronic and Facsimile Availability The SDN List and additional... pursuant to Executive Order 13315, as amended, should be removed from the SDN List. The following...
78 FR 31632 - Unblocking of (1) One Individual Designated Pursuant to Executive Order 13573

Federal Register 2010, 2011, 2012, 2013, 2014

2013-05-24

... the list of Specially Designated Nationals and Blocked Persons (``SDN List''). DATES: The removal of this individual from the SDN List is effective as of May 16, 2013. FOR FURTHER INFORMATION CONTACT... removed from the SDN List. The following designation is removed from the SDN List: Individual 1. RAJIHA...
78 FR 23332 - Unblocking of One Specially Designated Global Terrorist Pursuant to Executive Order 13224

Federal Register 2010, 2011, 2012, 2013, 2014

2013-04-18

... Designated Nationals and Blocked Persons (``SDN List''). DATES: The removal of this individual from the SDN... 20220, tel.: 202/622-2490. SUPPLEMENTARY INFORMATION: Electronic and Facsimile Availability The SDN List... determined that this individual should be removed from the SDN List. Individual 1. UMAR, Madhat Mursi Al...
76 FR 73781 - Unblocking of One Specially Designated Terrorist Pursuant to Executive Order 12947

Federal Register 2010, 2011, 2012, 2013, 2014

2011-11-29

... Blocked Persons (``SDN List''). DATES: The removal of this individual from the SDN List is effective as of...-2490. SUPPLENTARY IMFORMATION: Electronic and Facsimile Availability The SDN List and additional... determined that this individual should be removed from the SDN List. The following individual is removed from...
75 FR 81718 - Unblocking of Specially Designated Nationals and Blocked Persons Pursuant to Executive Order...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-12-28

... Foreign Assets Control (``OFAC'') is publishing the names of ten individuals whose property and interests... Designated Nationals and Blocked Persons (``SDN List'') of the ten individuals identified in this notice... Annex to Executive Order 13288 included 77 individuals, including nine of the ten individuals identified...

77 FR 44717 - Unblocking of Specially Designated Nationals and Blocked Persons Pursuant to the Foreign...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-07-30

... Foreign Assets Control (``OFAC'') is publishing the names of ten individuals and nine entities whose... ten individuals and nine entities identified in this notice whose property and interests in property... international narcotics trafficking. On July 24, 2012, the Director of OFAC removed from the SDN List the ten...
75 FR 54697 - Unblocking of Thirteen Specially Designated Nationals Pursuant to Executive Order 13224

Federal Register 2010, 2011, 2012, 2013, 2014

2010-09-08

... removing the names of ten entities and three individuals from the list of Specially Designated Nationals... Commit, Threaten To Commit, or Support Terrorism. DATES: The removal of ten entities and three... Foreign Assets Control has determined that these ten entities and three individuals no longer meet the...
78 FR 28291 - Unblocking of 1 Individual Designated Pursuant to Executive Order 13572; Correction

Federal Register 2010, 2011, 2012, 2013, 2014

2013-05-14

...: Notice; correction. SUMMARY: On April 25, 2013, the Treasury Department's Office of Foreign Assets... from the SDN List was effective as of Thursday, April 18, 2013. FOR FURTHER INFORMATION CONTACT... on April 25, 2013 at 78 FR 24468, OFAC incorrectly described the property and interests in property...
77 FR 33562 - Unblocking of Specially Designated Nationals and Blocked Persons Pursuant to the Foreign...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-06-06

... 3, 1999, the Kingpin Act was signed into law by the President of the United States. The Kingpin Act provides a statutory framework for the President to impose sanctions against significant foreign narcotics.... jurisdiction, owned or controlled by significant foreign narcotics traffickers as identified by the President...
77 FR 41479 - Unblocking of Specially Designated Nationals and Blocked Persons Pursuant to the Foreign...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-07-13

..., 1999, the Kingpin Act was signed into law by the President of the United States. The Kingpin Act provides a statutory framework for the President to impose sanctions against significant foreign narcotics.... jurisdiction, owned or controlled by significant foreign narcotics traffickers as identified by the President...
77 FR 33561 - Unblocking of Specially Designated Nationals and Blocked Persons Pursuant to Executive Order 12978

Federal Register 2010, 2011, 2012, 2013, 2014

2012-06-06

... On October 21, 1995, the President, invoking the authority, inter alia, of the International..., October 24, 1995) (the ``Order''). In the Order, the President declared a national emergency to deal with... Cotilla 2032, Piso 10, Colonia Americana, Guadalajara, Jalisco, Mexico; Ignacio Ramos Praslow 640...
75 FR 30110 - Unblocking of Specially Designated National and Blocked Persons Pursuant to the Foreign Narcotics...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-05-28

..., 1999. The Act provides a statutory framework for the President to impose sanctions against significant... identified by the President. In addition, the Secretary of the Treasury consults with the Attorney General... Tecnologico, Tijuana, Baja California, Mexico; Calle Geiser 101, Colonia Colinas de Agua Caliente, Tijuana...
77 FR 54949 - Unblocking of Specially Designated Nationals and Blocked Persons Pursuant to Executive Order 12978

Federal Register 2010, 2011, 2012, 2013, 2014

2012-09-06

... (Colombia) (INDIVIDUAL) [SDNT]. 5. HACHITO SANCHEZ, Angel Alberto, c/o COPSERVIR LTDA., Bogota, Colombia.... GAMBA SANCHEZ, Fernando, c/o DISTRIBUIDORA DE DROGAS CONDOR S.A., Bogota, Colombia; DOB 03 Nov 1962...; Cedula No. 52492258 (Colombia) (INDIVIDUAL) [SDNT]. 17. MORENO GOMEZ, Ingrid Del Carmen, c/o CAJA...
77 FR 76625 - Unblocking of Specially Designated Nationals and Blocked Persons Pursuant to Executive Order 12978

Federal Register 2010, 2011, 2012, 2013, 2014

2012-12-28

... EUROMAR CARIBE S.A., Cartagena, Colombia; c/o INVERSIONES EL PROGRESO S.A., Cartagena, Colombia; c/o INVERSIONES LAMARC S.A., Cartagena, Colombia; Carrera 4 No. 4-139, Cartagena, Colombia; Cedula No. 73085554.../o INVERSIONES EL PROGRESO S.A., Cartagena, Colombia; Cedula No. 40976673 (Colombia) (individual...
77 FR 25536 - Unblocking of Specially Designated Nationals and Blocked Persons Pursuant to Executive Order 12978

Federal Register 2010, 2011, 2012, 2013, 2014

2012-04-30

...); Passport 31971236 (Colombia) (individual) [SDNT]. 8. ARISTIZABAL ATEHORTUA, Jaime Alberto, c/o INVERSIONES... MONDRAGON, Ana Dolores, c/o COMPAX LTDA., Cali, Colombia; c/o INVERSIONES Y CONSTRUCCIONES COSMOVALLE LTDA., Cali, Colombia; c/o INVERSIONES Y CONSTRUCCIONES ABC S.A., Cali, Colombia; DOB 22 Dec 1911; Cedula No...
77 FR 63420 - Unblocking of Specially Designated Nationals and Blocked Persons Pursuant to Executive Order 12978

Federal Register 2010, 2011, 2012, 2013, 2014

2012-10-16

... INMOBILIARIA HOTELERA DEL CARIBE LTDA., Barranquilla, Colombia; c/o INVERSIONES HOTELERAS DEL LITORAL LTDA., Barranquilla, Colombia; c/o INVERSIONES PRADO TRADE CENTER LTDA., Barranquilla, Colombia; c/o NEGOCIOS Y... VIEJO, Alfredo, c/o INVERSIONES EL PROGRESO S.A., Cartagena, Colombia; DOB 15 Dec 1954; Cedula No...
76 FR 66132 - Unblocking of Specially Designated Nationals and Blocked Persons Pursuant to Executive Order 12978

Federal Register 2010, 2011, 2012, 2013, 2014

2011-10-25

...., Miami, FL; c/o URBANIZADORA ALTAVISTA INTERNACIONAL S.A., Barranquilla, Colombia; c/o MLA INVESTMENTS... CONSTRUCTORA ALTAVISTA INTERNACIONAL S.A., Barranquilla, Colombia; c/o CONFECCIONES LORD S.A., Barranquilla...); Passport AF547128 (Colombia) (individual) [SDNT] Entities: BANCA DE INVERSION Y MERCADO DE CAPITALES S.A...
75 FR 79443 - Unblocking of Specially Designated National Pursuant to Executive Order 13413

Federal Register 2010, 2011, 2012, 2013, 2014

2010-12-20

... the Democratic Republic of Congo'' and who has been removed from OFAC's list of Specially Designated... imposed sanctions relating to the situation in the Democratic Republic of the Congo. Section 1 of the... Congo, Democratic Republic of the; Passport C0323172 (Congo, Democratic Republic of the) (individual...
Paleomagnetic quantification of upper-plate deformation during Miocene detachment faulting in the Mohave Mountains, Arizona

USGS Publications Warehouse

Pease, V.; Hillhouse, J.W.; Wells, R.E.

2005-01-01

Paleomagnetic data from Miocene (???20 Ma) volcanic rocks and dikes of west central Arizona reveal the tilt history of Proterozoic crystalline rocks in the hanging wall of the Chemehuevi-Whipple Mountains detachment fault. We obtained magnetization data from dikes and flows in two structural blocks encompassing Crossman Peak and Standard Wash in the Mohave Mountains. In the Crossman block the dike swarm records two components of primary magnetization: (1) CNH, a normal polarity, high-unblocking-temperature or high-coercivity component (inclination, I = 48.5??, declination, D = 6.4??), and (2) CRHm, a reversed polarity, high-temperature or high-coercivity component (I = -33.6??, D = 197.5??). Argon age spectra imply that the dikes have not been reheated above 300??C since their emplacement, and a baked-contact test suggests that the magnetization is likely to be Miocene in age. CRHm deviates from the expected direction of the Miocene axial dipole field and is best explained as a result of progressive tilting about the strike of the overlying andesite flows. These data suggest that the Crossman block was tilted 60?? to the southwest prior to intrusion of the vertical dike swarm, and the block continued to tilt during a magnetic field reversal to normal polarity (CNH). Miocene dikes in the Crossman block are roughly coplanar, so the younger dikes with normal polarity magnetization intruded along planes of weakness parallel to the earlier reversed polarity swarm. An alternative explanation involves CNH magnetization being acquired later during hydrothermal alteration associated with the final stages of dike emplacement. In the Standard Wash block, the primary component of magnetization is a dual-polarity, high-temperature or high-coercivity component (SWHl, I = 7.2??,D= 0.7??). To produce agreement between the expected Miocene magnetic direction and the SWH component requires (1) correcting for a 56?? tilt about the strike of flow bedding and (2) removing a counterclockwise vertical-axis rotation of 20??. The two rotations restore the Standard Wash dikes to vertical, make parallel the dike layering in the Crossman and Standard Wash blocks, and align the strikes of bedding in both blocks. Geologic mapping, geochemical evidence, and paleomagnetic data are consistent with the upper plate of the Mohave Mountains having tilted in response to formation of the underlying detachment fault.
SU-D-12A-07: Optimization of a Moving Blocker System for Cone-Beam Computed Tomography Scatter Correction

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

Ouyang, L; Yan, H; Jia, X

2014-06-01

Purpose: A moving blocker based strategy has shown promising results for scatter correction in cone-beam computed tomography (CBCT). Different parameters of the system design affect its performance in scatter estimation and image reconstruction accuracy. The goal of this work is to optimize the geometric design of the moving block system. Methods: In the moving blocker system, a blocker consisting of lead strips is inserted between the x-ray source and imaging object and moving back and forth along rotation axis during CBCT acquisition. CT image of an anthropomorphic pelvic phantom was used in the simulation study. Scatter signal was simulated bymore » Monte Carlo calculation with various combinations of the lead strip width and the gap between neighboring lead strips, ranging from 4 mm to 80 mm (projected at the detector plane). Scatter signal in the unblocked region was estimated by cubic B-spline interpolation from the blocked region. Scatter estimation accuracy was quantified as relative root mean squared error by comparing the interpolated scatter to the Monte Carlo simulated scatter. CBCT was reconstructed by total variation minimization from the unblocked region, under various combinations of the lead strip width and gap. Reconstruction accuracy in each condition is quantified by CT number error as comparing to a CBCT reconstructed from unblocked full projection data. Results: Scatter estimation error varied from 0.5% to 2.6% as the lead strip width and the gap varied from 4mm to 80mm. CT number error in the reconstructed CBCT images varied from 12 to 44. Highest reconstruction accuracy is achieved when the blocker lead strip width is 8 mm and the gap is 48 mm. Conclusions: Accurate scatter estimation can be achieved in large range of combinations of lead strip width and gap. However, image reconstruction accuracy is greatly affected by the geometry design of the blocker.« less
Blocking, unblocking, and overexpectation in autoshaping with pigeons.

PubMed

Khallad, Y; Moore, J

1996-05-01

Three experiments used pigeons in an autoshaping procedure and a single-subject design to examine compound stimulus control in classical conditioning. Experiment 1 examined the blocking effect, and Experiment 2 examined the unblocking effect. In both experiments, response-independent food was first delivered intermittently in the presence of one distinctively colored houselight but not another. Then, conventional autoshaping trials were carried out in the presence of each houselight. In Experiment 1, the keylight readily elicited responding in the presence of the houselight that had been negatively correlated with food, but not in the presence of the houselight that had been positively correlated with food. In Experiment 2, the keylight readily elicited responding in the presence of the houselight positively correlated with food, but only when the amount of food used on the autoshaping trials was either greater or less than that previously delivered in the presence of the houselight. Experiment 3 examined the overexpectation effect. Conventional autoshaping trials were first carried out by presenting each of two keylights individually. Then, additional autoshaping trials were carried out by presenting the two keylights as a compound, with either the same amount of food or a greater amount of food per trial. Finally, the keylights were retested by again presenting them individually. The number of responses per trial elicited by the keylights decreased when the amount of food used in compound trials was the same as that used in individual trials. However, the number of responses per trial remained approximately the same when the amount of food used in compound trials was greater than that used in individual trials. Taken together, the results of the three experiments demonstrate (a) the generality of the blocking, unblocking, and overexpectation effects by virtue of their extension to appetitive unconditioned stimuli; (b) the suitability of pigeons as subjects and autoshaping as a procedure for studying classical conditioning; and (c) the appropriateness of single-subject designs.
Blocking, unblocking, and overexpectation in autoshaping with pigeons

PubMed Central

Khallad, Yacoub; Moore, Jay

1996-01-01

Three experiments used pigeons in an autoshaping procedure and a single-subject design to examine compound stimulus control in classical conditioning. Experiment 1 examined the blocking effect, and Experiment 2 examined the unblocking effect. In both experiments, response-independent food was first delivered intermittently in the presence of one distinctively colored houselight but not another. Then, conventional autoshaping trials were carried out in the presence of each houselight. In Experiment 1, the keylight readily elicited responding in the presence of the houselight that had been negatively correlated with food, but not in the presence of the houselight that had been positively correlated with food. In Experiment 2, the keylight readily elicited responding in the presence of the houselight positively correlated with food, but only when the amount of food used on the autoshaping trials was either greater or less than that previously delivered in the presence of the houselight. Experiment 3 examined the overexpectation effect. Conventional autoshaping trials were first carried out by presenting each of two keylights individually. Then, additional autoshaping trials were carried out by presenting the two keylights as a compound, with either the same amount of food or a greater amount of food per trial. Finally, the keylights were retested by again presenting them individually. The number of responses per trial elicited by the keylights decreased when the amount of food used in compound trials was the same as that used in individual trials. However, the number of responses per trial remained approximately the same when the amount of food used in compound trials was greater than that used in individual trials. Taken together, the results of the three experiments demonstrate (a) the generality of the blocking, unblocking, and overexpectation effects by virtue of their extension to appetitive unconditioned stimuli; (b) the suitability of pigeons as subjects and autoshaping as a procedure for studying classical conditioning; and (c) the appropriateness of single-subject designs. PMID:16812810
Paleointensity Determinations of Basalts From The Emperor Seamounts

NASA Astrophysics Data System (ADS)

Carvallo, C.; Dunlop, D. J.; Özdemir, Ö.; Leg 197 Shipboard Scientific Party, Odp

Thellier-Thellier paleointensity experiments were carried out on sixty-six basaltic samples coming from three Emperor seamounts (Detroit, Nintoku and Koko) drilled during ODP Leg 197. Twelve samples yield reliable results. One samples from De- troit seamount (81 Ma) gives a VADM of 3.06+/-0.26×1022 Am2. Six samples from Nintoku (56 Ma) give VADMs between 2.90+/-0.15×1022 and 6.70+/-0.38×1022 Am2. Five samples from Koko seamount (44 Ma) give VADMs between 1.12+/-0.74×1022 and 2.94+/-0.20×1022 Am2. The low success rate was due to chemical changes during the heatings. Samples have a wide distribution of unblocking temperatures and bulk susceptibility variations during heating, revealing an important variation in oxidation state and titanium content with depth and between seamounts. In seafloor basalts, lowtemperature oxidation of ti- tanomagnetite can replace the original thermoremanent magnetization by a chemical remanent magnetization of reduced intensity, yielding too low paleointensity values. Therefore we need to do measurements such as lowtemperature properties and ther- momagnetic curves in order to identify the magnetic minerals and assess the reliability of the paleointensity determinations. However, assuming that the accepted samples did not undergo any maghemitization, the generally low VADM values we measured are in agreement with other records of paleointensities in this time range.
76 FR 65562 - Unblocking of One Specially Designated National or Blocked Person Pursuant to Executive Order...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-10-21

... Executive Order 13350 of July 30, 2004. DATES: The removal of this entity from the SDN List is effective as...-2490. SUPPLENTARY IMFORMATION: Electronic and Facsimile Availability The SDN List and additional... blocked pursuant to Executive Order 13315, as amended, should be removed from the SDN List. The following...
76 FR 55739 - Unblocking of One Specially Designated National or Blocked Person Pursuant to Executive Order...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-09-08

... Executive Order 13350 of July 30, 2004. DATES: The removal of this individual from the SDN List is effective...-2490. SUPPLEMENTARY INFORMATION: Electronic and Facsimile Availability The SDN List and additional... Executive Order 13315, as amended, should be removed from the SDN List. The following designation is removed...

77 FR 2777 - Unblocking of One Specially Designated National or Blocked Person Pursuant to Executive Order...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-01-19

... Executive Order 13350 of July 30, 2004. DATES: The removal of this individual from the SDN List is effective...) 622-2490. SUPPLEMENTARY INFORMATION: Electronic and Facsimile Availability The SDN List and additional... Executive Order 13315, as amended, should be removed from the SDN List. The following designation is removed...
76 FR 60129 - Unblocking of One Specially Designated National or Blocked Person Pursuant to Executive Order...

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2011-09-28

... Executive Order 13350 of July 30, 2004. DATES: The removal of this individual from the SDN List is effective...-2490. SUPPLEMENTARY INFORMATION: Electronic and Facsimile Availability The SDN List and additional... blocked pursuant to Executive Order 13315, as amended, should be removed from the SDN List. The following...
78 FR 1938 - Unblocking of One Individual and One Entity Blocked Pursuant to Executive Order 13315 of August...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-01-09

... list of Specially Designated Nationals and Blocked Persons (``SDN List''). DATES: The removal of the individual and entity from the SDN List is effective as of January 3, 2013. FOR FURTHER INFORMATION CONTACT... entity should be removed from the SDN List: Individual 1. SPECKMAN, Jeanine, United Kingdom (individual...
77 FR 2777 - Unblocking of One Specially Designated National or Blocked Person Pursuant to Executive Order...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-01-19

...,'' as amended by Executive Order 13350 of July 30, 2004. DATES: The removal of this entity from the SDN... The SDN List and additional information concerning OFAC are available from OFAC's web site ( www... property were blocked pursuant to Executive Order 13315, as amended, should be removed from the SDN List...
31 CFR 538.505 - Provision of certain legal services to the Government of Sudan, persons in Sudan, or benefitting...

Code of Federal Regulations, 2010 CFR

2010-07-01

... 31 Money and Finance: Treasury 3 2010-07-01 2010-07-01 false Provision of certain legal services... Finance: Treasury Regulations Relating to Money and Finance (Continued) OFFICE OF FOREIGN ASSETS CONTROL... receipt, from unblocked sources, of payment of professional fees and reimbursement of incurred expenses...
78 FR 21007 - Unblocking of Specially Designated Nationals and Blocked Persons Pursuant to Executive Order 13348

Federal Register 2010, 2011, 2012, 2013, 2014

2013-04-08

... 14 Dec 1947; alt. DOB 18 Oct 1946; nationality Ukraine; Passport 5280007248D (Germany); alt. Passport 18106739D (Germany); alt. Passport 6019832 (Israel) issued 06 Nov 1994 expires 05 Nov 1999; alt. Passport 9001689 (Israel) issued 23 Jan 1997 expires 22 Jan 1999; alt. Passport KI0861177 (Russia); alt. Passport...
75 FR 21985 - Virginia Graeme Baker Pool and Spa Safety Act; Interpretation of Unblockable Drain

Federal Register 2010, 2011, 2012, 2013, 2014

2010-04-27

...'' as ``a drain of any size and shape that a human body cannot sufficiently block to create a suction... the blocking element was not representative of ``human skin'' and therefore did not fully represent a body's ability to adhere to or seal around an outlet cover. Response: The Commission agrees that the...
77 FR 50210 - Unblocking of One (1) Individual Designated Pursuant to Executive Order 13573

Federal Register 2010, 2011, 2012, 2013, 2014

2012-08-20

... removed from the SDN List. The following designation is removed from the SDN List: Individual 1. HIJAB, Riyad (a.k.a. HIJAB, Riyad Farid), Syria; DOB 1966; POB Deir Ezzor, Syria; Prime Minister (individual... concerning OFAC are available from OFAC's Web site ( www.treas.gov/ofac ) or via facsimile through a 24-hour...
31 CFR 586.518 - Authorization of release of certain blocked transfers by U.S. financial institutions.

Code of Federal Regulations, 2010 CFR

2010-07-01

... blocked transfers by U.S. financial institutions. 586.518 Section 586.518 Money and Finance: Treasury... transfers by U.S. financial institutions. (a) Subject to the limitation set forth in this paragraph, U.S. financial institutions are authorized to unblock and return to the remitting party funds blocked pursuant to...
31 CFR 585.526 - Authorization for release of certain blocked transfers by U.S. financial institutions.

Code of Federal Regulations, 2010 CFR

2010-07-01

... blocked transfers by U.S. financial institutions. 585.526 Section 585.526 Money and Finance: Treasury... institutions. (a) U.S. financial institutions are authorized to unblock and return to the remitting party funds... were not destined for an account on the books of a U.S. financial institution, which account was...
78 FR 36638 - Unblocking of Specially Designated Nationals and Blocked Persons Pursuant to the Foreign...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-06-18

... December 3, 1999, the Kingpin Act was signed into law by the President of the United States. The Kingpin Act provides a statutory framework for the President to impose sanctions against significant foreign... by the President. In addition, the Secretary of the Treasury consults with the Attorney General, the...
78 FR 8702 - Unblocking of Specially Designated Nationals and Blocked Persons Pursuant to the Foreign...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-02-06

.... A. de Sta. Na. 21741, Colonia Infonavit Presidentes, Tijuana, Baja California CP 22576, Mexico; c/o... 334, Colonia Playas de Tijuana, Tijuana, Baja California CP 22300, Mexico; c/o CASA DE EMPENO RIO..., Calle Lago Chaira 323, Colonia Vista Dorada, Ensenada, Baja California CP 22800, Mexico; c/o CASA DE...
78 FR 36635 - Unblocking of Specially Designated Nationals and Blocked Persons Pursuant to Executive Order 12978

Federal Register 2010, 2011, 2012, 2013, 2014

2013-06-18

.../ofac ) or via facsimile through a 24-hour fax-on demand service at (202) 622-0077. Background On October 21, 1995, the President, invoking the authority, inter alia, of the International Emergency... 24, 1995) (the ``Order''). In the Order, the President declared a national emergency to deal with the...
75 FR 80113 - Unblocking of One Specially Designated National Pursuant to Executive Order 13224

Federal Register 2010, 2011, 2012, 2013, 2014

2010-12-21

... International Emergency Economic Powers Act, 50 U.S.C. 1701-1706, and the United Nations Participation Act of 1945, 22 U.S.C. 287c, imposing economic sanctions on persons who commit, threaten to commit, or support... as subject to the economic sanctions. The Order authorizes the Secretary of the Treasury, in...
75 FR 67166 - Unblocking of Two Specially Designated Nationals Pursuant to Executive Order 13224

Federal Register 2010, 2011, 2012, 2013, 2014

2010-11-01

... ``Order'') pursuant to the International Emergency Economic Powers Act, 50 U.S.C. 1701-1706, and the United Nations Participation Act of 1945, 22 U.S.C. 287c, imposing economic sanctions on persons who... Order various individuals and entities as subject to the economic sanctions. The Order authorizes the...
77 FR 2606 - Unblocking of Specially Designated Nationals and Blocked Persons Pursuant to Executive Order 12978

Federal Register 2010, 2011, 2012, 2013, 2014

2012-01-18

.... RENTERIA CAICEDO, Beatriz Eugenia, c/o INVERSIONES AGROINDUSTRIALES DEL OCCIDENTE LTDA., Bogota, Colombia... ILOVIN S.A., Bogota, Colombia; c/o INVERSIONES DEL PRADO ABDALA SAIEH Y CIA. S.C.A., Barranquilla...., Bogota, Colombia; c/o INVERSIONES DEL PRADO ABDALA SAIEH Y CIA. S.C.A., Barranquilla, Colombia; c/o KAREN...
78 FR 47492 - Unblocking of Specially Designated Nationals and Blocked Persons Pursuant to Executive Order 12978

Federal Register 2010, 2011, 2012, 2013, 2014

2013-08-05

..., Walter, c/o CARMILE INVERSIONES LOPEZ Y CIA. S.C.A., Cali, Colombia; c/o CONSTRUCTORA SANTA TERESITA S.A., Cali, Colombia; c/o INVERSIONES MEDICAS Y QUIRUGICAS ESPECIALIZADAS LTDA., Cali, Colombia; c/o...) (individual) [SDNT]. 7. PABON ALVARADO, Gustavo Alberto, c/o INVERSIONES MPS S.A., Bogota, Colombia; c/o...
76 FR 48946 - Unblocking of Specially Designated Nationals and Blocked Persons Pursuant to Executive Order 12978

Federal Register 2010, 2011, 2012, 2013, 2014

2011-08-09

... Fundacion Para La Educacion Y El Desarrollo Social, Cali, Colombia; c/o Inversiones Corporativas LTDA., Cali, Colombia; c/o Inversiones Sardi Alzate S.C.S., Cali, Colombia; c/o Outsourcing De Operaciones S.A., Bogota... La Educacion Y El Desarrollo Social, Cali, Colombia; c/o Inversiones Corporativas LTDA., Cali...
77 FR 41479 - Unblocking of Specially Designated Nationals and Blocked Persons Pursuant to Executive Order 12978

Federal Register 2010, 2011, 2012, 2013, 2014

2012-07-13

..., Maria Teresa), c/o INVERSIONES MPS S.A., Bogota, Colombia; c/o PROYECTOS Y SOLUCIONES INMOBILIARIA LTDA... S.A., Quito, Ecuador; c/o INVERSIONES ARA LTDA., Cali, Colombia; c/o DISTRIBUIDORA DE DROGAS LA....A., Bogota, Colombia; c/o DROCARD S.A., Bogota, Colombia; c/o INVERSIONES ESPANOLES FEMCAR S.L...
77 FR 43429 - Unblocking of 1 Individual and 2 Entities Designated Pursuant to Executive Order 13315

Federal Register 2010, 2011, 2012, 2013, 2014

2012-07-24

.... The following designations are removed from the SDN List: Individual 1. KARAM, Nabil Victor, c/o ALFA COMPANY LIMITED FOR INTERNATIONAL TRADING AND MARKETING, P.O. Box 212953, Amman 11121, Jordan; c/o ALFA... 910606, Amman 11191, Jordan; DOB 1954; nationality Lebanon (individual) [IRAQ2]. Entities 1. ALFA COMPANY...

Use of intrathecal urokinase in repeated shunt and external ventricular drain blockage from high CSF protein due to an optic pathway glioma.

PubMed

Shooman, David; Vajramani, Girish V; Davidson, Jennifer; Sparrow, Owen C

2010-05-01

High cerebrospinal fluid (CSF) protein is a recognised association of optic pathway gliomas. This can occlude ventriculoperitoneal (VP) shunt catheters or external ventricular drains (EVD). We describe an 8-year-old boy with an optic pathway glioma, who had frequent episodes of a blocked VP shunt and EVD due to high CSF protein level. This responded favourably to repeated urokinase instillation into the catheter lumen. We present the course of treatment and the method of administration and review the literature behind thrombolytic therapy for occluded catheter devices. Intrathecal urokinase was effective in unblocking the EVD and lysing the protein clots within the ventricle. We found no previously published cases of intrathecal urokinase for this problem. This novel intervention seemed promising as a safe and effective means of maintaining EVD patency in cases complicated by excessive protein loads in CSF and hydrocephalus.
Temperature behavior of the antiferromagnetic susceptibility of nanoferrihydrite from the measurements of the magnetization curves in fields of up to 250 kOe

NASA Astrophysics Data System (ADS)

Balaev, D. A.; Popkov, S. I.; Krasikov, A. A.; Balaev, A. D.; Dubrovskiy, A. A.; Stolyar, S. V.; Yaroslavtsev, R. N.; Ladygina, V. P.; Iskhakov, R. S.

2017-10-01

The cross-breeding problem of the temperature dependence of the antiferromagnetic susceptibility of ferrihydrite nanoparticles is considered. Iron ions Fe3+ in ferrihydrite are ordered antiferromagnetically; however, the existence of defects on the surface and in the bulk of nanoparticles induces a noncompensated magnetic moment that leads to a typical superparamagnetic behavior of ensemble of the nanoparticles with a characteristic blocking temperature. In an unblocked state, magnetization curves of such objects are described as a superposition of the Langevin function and the linear-in-field contribution of the antiferromagnetic "core" of the nanoparticles. According to many studies of the magnetization curves performed on ferrihydrite (and related ferritin) nanoparticles in fields to 60 kOe, dependence χAF( T) decreases as temperature increases, which was related before to the superantiferromagnetism effect. As the magnetic field range increases to 250 kOe, the values of χAF obtained from an analysis of the magnetization curves become lower in magnitude; however, the character of the temperature evolution of χAF is changed: now, dependence χAF( T) is an increasing function. The latter is typical for a system of AF particles with random orientation of the crystallographic axes. To correctly determine the antiferromagnetic susceptibility of AF nanoparticles (at least, ferrihydrite) and to search for effects related to the superantiferromagnetism effect, it is necessary to use in experiments the range of magnetic field significantly higher than that the standard value 60 kOe used in most experiments. The study of the temperature evolution of the magnetization curves shows that the observed crossover is due to the existence of small magnetic moments in the samples.
Cation reordering in natural titanomagnetites and implications for paleointensity studies

NASA Astrophysics Data System (ADS)

Bowles, J. A.; Jackson, M. J.; Gee, J. S.

2013-05-01

Successful paleointensity experiments hinge on the underlying assumption of reciprocity; the remanence acquired over a particular temperature range should be fully removed over the same temperature range, and vice versa. This means that the blocking (TB) and unblocking (TUB) temperature spectra are identical and do not change during the course of the experiment. We will present the results of recent work demonstrating that some natural titanomagnetites undergo cation reordering on laboratory timescales and at temperatures at or below the Curie temperature (TC). The bulk composition of the titanomagnetites (Fe3-xTixO4) varies between approximately 0.2 < x < 0.4, with moderate degrees of Mg and Al substitution. Although there is no attendant structural or chemical alteration, the re-distribution of ferric and ferrous iron cations results in reversible changes in Curie temperature of up to 150°C. This necessarily changes the blocking temperature spectrum as a function of prior thermal history. These changes in TC, TUB and TB clearly pose problems for all paleointensity experiments, but the effects may be most apparent during Thellier-type experiments where the sample is step-wise heated to increasingly higher temperatures. The blocking temperature distribution will be expected to change over the course of the experiment even in the absence of chemical alteration, and one can expect the experiment to fail. We will explore the effects of cation redistribution on paleointensity experiments through numerical models and by comparison with paleointensity data from pumice samples taken from the 1980 pyroclastic flows at Mt. St. Helens (MSH). In the MSH samples, two phases are typically present: a predominantly multi-domain, homogeneous titanomagnetite (associated with the cation reordering) and an oxyexsolved, single-domain to pseudo-single-domain phase with ilmenite lamellae in a magnetite-rich host. Samples that result in technically successful paleointensity experiments that give the correct field value are most likely to be dominated by the oxyexsolved phase. By contrast, samples with a considerable proportion of the homogeneous phase typically fail the paleointensity experiments and have unstable magnetization behavior at temperatures associated with cation reordering on laboratory time scales. In many samples with both phases, pTRM checks pass at both low (<300°C) and high (>500°C) temperatures, but fail in the intermediate temperature window. The composition of the titanomagnetites that exhibit this cation reordering effect are extremely common in rocks of andesitic, dacitic, and rhyolitic composition, as well as in some basalts. Cation reordering may therefore be a previously unrecognized cause for failure in paleointensity experiments.
Effect of interscalene block on intraocular pressure and ocular perfusion pressure.

PubMed

Basaran, Betul; Yilbas, Aysun Ankay; Gultekin, Zeki

2017-10-23

Interscalene block (ISB) is commonly associated with Horner's syndrome due to spread of local anesthetic to the cervical sympathetic chain. Postganglionic neurons that originate from superior cervical ganglia form the sympathetic innervation of eye. Decrease in sympathetic tone may change intraocular pressure (IOP) and ocular perfusion pressure (OPP). The aim of the study was to investigate whether ISB affects IOP and/or OPP. Thirty patients scheduled for ambulatory shoulder surgery under regional anesthesia with a single-shot ISB (15 mL 0.5% bupivacaine and 15 mL 2% lidocaine) were recruited. The IOP and OPP in both eyes, mean arterial pressure (MAP), heart rate (HR) and end-tidal CO 2 (ETCO 2 ) were measured before ISB and 5, 10, 20, 30 and 60 min after ISB in the beach-chair position. The baseline IOP and OPP were similar in the blocked and unblocked sides (IOP 17.60 ± 1.69 and 17.40 ± 1.96 respectively p = 0.432; OPP 49.80 ± 8.20 and 50 ± 8.07 respectively p = 0.432). The IOP in the blocked side significantly decreased between 10th to 60th min following ISB, compared to the baseline values (p < 0.001). The OPP in the blocked side significantly increased from 10th to 60th min (p < 0.001) whereas, there were no significant changes in IOP and OPP throughout the measurement period in the unblocked side. ISB decreased IOP in the blocked side. ISB could be considered as a safe regional technique of choice in elderly patients at high risk for developing glaucoma.
78 FR 10000 - Unblocking of Five (5) Individuals as Specially Designated Global Terrorists Pursuant to...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-02-12

... following individuals are removed from the SDN List: Individuals 1. ALI, Abbas Abdi, Mogadishu, Somalia.... MSALAM, Fahad Ally; a.k.a. MSALAM, Fahid Mohammed Ali; a.k.a. MSALAM, Mohammed Ally; a.k.a. MUSALAAM, Fahid Mohammed Ali; a.k.a. SALEM, Fahid Muhamad Ali); DOB 19 Feb 1976; POB Mombasa, Kenya; citizen Kenya...
Unblocking Occluded Genres in Graduate Writing: Thesis and Dissertation Support Services at North Carolina State University

ERIC Educational Resources Information Center

Autry, Meagan Kittle; Carter, Michael

2015-01-01

In 2013, the Graduate School at North Carolina State University launched Thesis and Dissertation Support Services, a rhetorical, genre-based approach to assisting students with their graduate writing. Through a description of the program's founding, goals, and first year of services, we summarize this genre-based approach that is informed by the…
31 CFR 501.806 - Procedures for unblocking funds believed to have been blocked due to mistaken identity.

Code of Federal Regulations, 2010 CFR

2010-07-01

... believed to have been blocked due to mistaken identity. 501.806 Section 501.806 Money and Finance: Treasury... funds believed to have been blocked due to mistaken identity. When a transaction results in the blocking... party to the transaction believes the funds have been blocked due to mistaken identity, that party may...
31 CFR 501.806 - Procedures for unblocking funds believed to have been blocked due to mistaken identity.

Code of Federal Regulations, 2012 CFR

2012-07-01

... believed to have been blocked due to mistaken identity. 501.806 Section 501.806 Money and Finance: Treasury... funds believed to have been blocked due to mistaken identity. When a transaction results in the blocking... party to the transaction believes the funds have been blocked due to mistaken identity, that party may...
31 CFR 501.806 - Procedures for unblocking funds believed to have been blocked due to mistaken identity.

Code of Federal Regulations, 2011 CFR

2011-07-01

... believed to have been blocked due to mistaken identity. 501.806 Section 501.806 Money and Finance: Treasury... funds believed to have been blocked due to mistaken identity. When a transaction results in the blocking... party to the transaction believes the funds have been blocked due to mistaken identity, that party may...
31 CFR 501.806 - Procedures for unblocking funds believed to have been blocked due to mistaken identity.

Code of Federal Regulations, 2013 CFR

2013-07-01

... believed to have been blocked due to mistaken identity. 501.806 Section 501.806 Money and Finance: Treasury... funds believed to have been blocked due to mistaken identity. When a transaction results in the blocking... party to the transaction believes the funds have been blocked due to mistaken identity, that party may...
31 CFR 501.806 - Procedures for unblocking funds believed to have been blocked due to mistaken identity.

Code of Federal Regulations, 2014 CFR

2014-07-01

... believed to have been blocked due to mistaken identity. 501.806 Section 501.806 Money and Finance: Treasury... funds believed to have been blocked due to mistaken identity. When a transaction results in the blocking... party to the transaction believes the funds have been blocked due to mistaken identity, that party may...
75 FR 65557 - Unblocking of Specially Designated Nationals and Blocked Persons Pursuant to Executive Order 12978

Federal Register 2010, 2011, 2012, 2013, 2014

2010-10-25

...://www.treas.gov/ofac ) or via facsimile through a 24-hour fax-on-demand service at (202) 622-0077..., October 24, 1995) (the ``Order''). In the Order, the President declared a national emergency to deal with... Treasury, in consultation with the Attorney General and Secretary of State: (a) To play a significant role...
75 FR 61573 - Unblocking of Specially Designated Nationals and Blocked Persons Pursuant to Executive Order 12978

Federal Register 2010, 2011, 2012, 2013, 2014

2010-10-05

....gov/ofac ) or via facsimile through a 24-hour fax-on demand service at (202) 622-0077. Background On... 24, 1995) (the ``Order''). In the Order, the President declared a national emergency to deal with the... Treasury, in consultation with the Attorney General and Secretary of State: (a) To play a significant role...
31 CFR 586.519 - Release of certain funds held at overseas branches of U.S. financial institutions.

Code of Federal Regulations, 2010 CFR

2010-07-01

... overseas branches of U.S. financial institutions. 586.519 Section 586.519 Money and Finance: Treasury... of U.S. financial institutions. Specific licenses may be issued on a case-by-case basis to permit the overseas branches of U.S. financial institutions to unblock deposit accounts that were blocked pursuant to...
77 FR 21154 - Unblocking of Blocked Persons Pursuant to Executive Order 13067 and Executive Order 13412

Federal Register 2010, 2011, 2012, 2013, 2014

2012-04-09

... from the SDN List: 1. PEOPLE'S CO-OPERATIVE BANK, P.O. Box 922, Khartoum, Sudan; [SUDAN] 2. UNITY BANK, Bariman Avenue, P.O. Box 408, Khartoum, Sudan; Now part of BANK OF KHARTOUM GROUP; [SUDAN] Dated: January... entities, and the Central Bank of Sudan. On October 13, 2006, the President, invoking the authority of...
78 FR 72751 - Unblocking of Specially Designated Nationals and Blocked Persons Pursuant to the Foreign...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-12-03

... SERVICIO AEREO LEO LOPEZ, S.A. DE C.V., Chihuahua, Chihuahua, Mexico; Fernando De Borja 509, Chihuahua... REZA, Jorge Luis, c/o SERVICIO AEREO LEO LOPEZ, S.A. DE C.V., Chihuahua, Chihuahua, Mexico; Calle... 3, 1999, the Kingpin Act was signed into law by the President of the United States. The Kingpin Act...
76 FR 25406 - Unblocking of Specially Designated Nationals and Blocked Persons Pursuant to the Foreign...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-05-04

... PROVINCIA S.A. DE C.V., Tijuana, Baja California, Mexico; c/o COMPLEJO TURISTICO OASIS, S.A. de C.V., Playas de Rosarito, Rosarito, Baja California, Mexico; c/o PLAYA MAR S.A. DE C.V., Tijuana, Baja California... President to impose sanctions against significant foreign narcotics traffickers and their organizations on a...
31 CFR 500.559 - Accounts of North Korean, North Vietnamese, Cambodian or South Vietnamese sole proprietorships.

Code of Federal Regulations, 2010 CFR

2010-07-01

... Korea, North Viet-Nam, Cambodia, or South Viet-Nam if the proprietor has emigrated from those countries... licenses do not unblock any indebtedness of the proprietorship due to persons in North Korea, North Viet... 31 Money and Finance: Treasury 3 2010-07-01 2010-07-01 false Accounts of North Korean, North...
Telepsychiatry, the satellite system and family consultation.

PubMed

Paul, N L

1997-01-01

A pilot telepsychiatry session was conducted with the US Department of Defense Satellite Communication System. The subjects were a family incompletely divorced many years before. There were two satellite interviews with this family. Bringing together all members of the original family so that questions could be addressed as to what happened when the children were very young unblocked a 13-year-old communication problem.
75 FR 36782 - Unblocking of Specially Designated Nationals and Blocked Persons Pursuant to Executive Order 12978

Federal Register 2010, 2011, 2012, 2013, 2014

2010-06-28

... INVERSIONES CAMINO REAL S.A., Cali, Colombia; c/o GRACADAL S.A., Cali, Colombia; c/o INTERAMERICA DE..., Colombia; c/o INVERSIONES Y CONSTRUCCIONES COSMOVALLE LTDA., Cali, Colombia; c/o COMPAX LTDA., Cali..., Cali, Colombia; c/o INVERSIONES MONDRAGON Y CIA. S.C.S., Cali, Colombia; c/o MARIELA MONDRAGON DE R. Y...

78 FR 21495 - Unblocking of Specially Designated Nationals and Blocked Persons Pursuant To Executive Order 12978

Federal Register 2010, 2011, 2012, 2013, 2014

2013-04-10

...., Cali, Colombia; c/o INVERSIONES MONDRAGON Y CIA. S.C.S., Cali, Colombia; c/o CREDIREBAJA S.A., Cali..., Colombia; c/o DECAFARMA S.A., Bogota, Colombia; c/o DROCARD S.A., Bogota, Colombia; c/o INVERSIONES Y CONSTRUCCIONES COSMOVALLE LTDA., Cali, Colombia; c/o JAROMO INVERSIONES S.L., Madrid, Spain; c/o PROSPECTIVA...
75 FR 54696 - Unblocking of Specially Designated Nationals and Blocked Persons Pursuant to Executive Order 12978

Federal Register 2010, 2011, 2012, 2013, 2014

2010-09-08

... ALERO S.A., Cali, Colombia; c/o INVERSIONES Y CONSTRUCCIONES COSMOVALLE LTDA., Cali, Colombia; c/o INVERSIETE S.A., Cali, Colombia; c/o INVERSIONES Y DISTRIBUCIONES A M M LTDA., Cali, Colombia; DOB 26 Oct...; c/o DROCARD S.A., Bogota, Colombia; c/o INVERSIONES CLAUPI S.L., Madrid, Colombia; DOB 30 Jun 1963...
77 FR 74918 - Unblocking of Specially Designated Nationals and Blocked Persons Pursuant to Executive Order 12978

Federal Register 2010, 2011, 2012, 2013, 2014

2012-12-18

.... 806, Bogota, Colombia; c/o COLOMBO ANDINA COMERCIAL COALSA LTDA., Bogota, Colombia; c/o INVERSIONES..., Elkin de Jesus, c/o FLOREZ HERMANOS LTDA., Medellin, Colombia; c/o INVERSIONES FLOREZ Y FLOREZ Y CIA S.C...., Cali, Colombia; c/o INVERSIONES CAMINO REAL S.A., Cali, Colombia; c/o BLANCO PHARMA S.A., Bogota...
Betting on change: modeling transitional probabilities to guide therapy development for opioid dependence.

PubMed

Carpenter, Kenneth M; Jiang, Huiping; Sullivan, Maria A; Bisaga, Adam; Comer, Sandra D; Raby, Wilfrid Noel; Brooks, Adam C; Nunes, Edward V

2009-03-01

This study investigated the process of change by modeling transitions among four clinical states encountered in 64 detoxified opiate-dependent individuals treated with daily oral naltrexone: no opiate use, blocked opiate use (i.e., opiate use while adhering to oral naltrexone), unblocked opiate use (i.e., opiate use after having discontinued oral naltrexone), and treatment dropout. The effects of baseline characteristics and two psychosocial interventions of differing intensity, behavioral naltrexone therapy (BNT) and compliance enhancement (CE), on these transitions were studied. Participants using greater quantities of opiates were more likely than other participants to be retained in BNT relative to CE. Markov modeling indicated a transition from abstinence to treatment dropout was approximately 3.56 times greater among participants in CE relative to participants in BNT, indicating the more comprehensive psychosocial intervention kept participants engaged in treatment longer. Transitions to stopping treatment were more likely to occur after unblocked opiate use in both treatments. Continued opiate use while being blocked accounted for a relatively low proportion of transitions to abstinence and may have more deleterious effects later in a treatment episode. (PsycINFO Database Record (c) 2009 APA, all rights reserved).
Free terminal amines in DNA-binding peptides alter the product distribution from guanine radicals produced by single electron oxidation.

PubMed

Konigsfeld, Katie M; Lee, Melissa; Urata, Sarah M; Aguilera, Joe A; Milligan, Jamie R

2012-03-01

Electron deficient guanine radical species are major intermediates produced in DNA by the direct effect of ionizing irradiation. There is evidence that they react with amine groups in closely bound ligands to form covalent crosslinks. Crosslink formation is very poorly characterized in terms of quantitative rate and yield data. We sought to address this issue by using oligo-arginine ligands to model the close association of DNA and its binding proteins in chromatin. Guanine radicals were prepared in plasmid DNA by single electron oxidation. The product distribution derived from them was assayed by strand break formation after four different post-irradiation incubations. We compared the yields of DNA damage produced in the presence of four ligands in which neither, one, or both of the amino and carboxylate termini were blocked with amides. Free carboxylate groups were unreactive. Significantly higher yields of heat labile sites were observed when the amino terminus was unblocked. The rate of the reaction was characterized by diluting the unblocked amino group with its amide blocked derivative. These observations provide a means to develop quantitative estimates for the yields in which these labile sites are formed in chromatin by exposure to ionizing irradiation.
Photoexcitation Cascade and Quantum-Relativistic Jets in Graphene

NASA Astrophysics Data System (ADS)

Lewandowski, Cyprian; Levitov, L. S.

2018-02-01

In Dirac materials linear band dispersion blocks momentum-conserving interband transitions, creating a bottleneck for electron-hole pair production and carrier multiplication in the photoexcitation cascade. Here we show that the decays are unblocked and the bottleneck is relieved by subtle many-body effects involving multiple off-shell e -h pairs. The decays result from a collective behavior due to simultaneous emission of many soft pairs. We discuss characteristic signatures of the off-shell pathways, in particular the sharp angular distribution of secondary carriers, resembling relativistic jets in high-energy physics. The jets can be directly probed using solid-state equivalent of particle detectors. Collinear scattering enhances carrier multiplication, allowing for emission of as many as ˜10 secondary carriers per single absorbed photon.
Charge tuning of nonresonant magnetoexciton phonon interactions in graphene.

PubMed

Rémi, Sebastian; Goldberg, Bennett B; Swan, Anna K

2014-02-07

Far from resonance, the coupling of the G-band phonon to magnetoexcitons in single layer graphene displays kinks and splittings versus filling factor that are well described by Pauli blocking and unblocking of inter- and intra-Landau level transitions. We explore the nonresonant electron-phonon coupling by high-magnetic field Raman scattering while electrostatic tuning of the carrier density controls the filling factor. We show qualitative and quantitative agreement between spectra and a linearized model of electron-phonon interactions in magnetic fields. The splitting is caused by dichroism of left- and right-handed circular polarized light due to lifting of the G-band phonon degeneracy, and the piecewise linear slopes are caused by the linear occupancy of sequential Landau levels versus ν.
Formal Semanol Specification of Ada.

DTIC Science & Technology

1980-09-01

concurrent task modeling involved very little change to the SEMANOL metalanguage. A primitive capable of initiating concurrent SEMANOL task processors...i.e., #CO-COMPUTE) and two primitivc-; corresponding to integer semaphores (i.c., #P and #V) were all that were required. In addition, these changes... synchronization techniques and choice of correct unblocking alternatives. We should note that it had been our original intention to use the Ada Translator program
76 FR 33810 - Unblocking of Blocked Persons Pursuant to Executive Order 13067 and Executive Order 13412

Federal Register 2010, 2011, 2012, 2013, 2014

2011-06-09

... Designated Nationals and Blocked Persons (``SDN List'') of the entities identified in this notice whose... E.O. 13067 and E.O. 13412 from the SDN List: BANK OF KHARTOUM (a.k.a. BANK OF KHARTOUM GROUP), P.O... [SUDAN] On May 26, 2011, OFAC removed from the SDN List the entity listed below, whose property and...
The Unblocking Leadership for Effectiveness of Teachers as Knowledge Staff: A Theoretical Framework for School Management

ERIC Educational Resources Information Center

Ozmusul, Mustafa

2015-01-01

When investigating the literature, it seems that little attention has been paid to what kind of leadership is needed for improving teacher effectiveness in terms of focusing on the obstacles that teachers face. Therefore, this study aims mainly to explore the obstacles that hinder the teachers when they do best in terms of receiving autonomy,…
31 CFR 515.505 - Certain Cuban nationals unblocked; transactions of certain other Cuban nationals lawfully present...

Code of Federal Regulations, 2010 CFR

2010-07-01

... specially designated national; and (2) Any entity that otherwise would be a national of Cuba solely because... until the individual thereafter becomes domiciled in or a permanent resident of Cuba, meets any of the criteria in § 515.302(a)(2) through (5), or is a “specially designated national” of Cuba, as that term is...
78 FR 24468 - Unblocking of 1 Individual Designated Pursuant to Executive Order 13572

Federal Register 2010, 2011, 2012, 2013, 2014

2013-04-25

... is removed from the SDN List: Individual AL-KUZBARI, Nabil Rafik (a.k.a. AL-KOUZBARI, Nabil; a.k.a. AL- KUZBARI, Nabil; a.k.a. AL-KUZBARI, Nabil Rafiq; a.k.a. KUSBARI, Nabil; a.k.a. KUZBARI, Ahmad; a.k.a. KUZBARI, Ahmad Nabil; a.k.a. KUZBARI, Nabil R.); DOB 20 Sep 1936; POB Damascus, Syria; citizen...
78 FR 47827 - Unblocking of Specially Designated Nationals and Blocked Persons Pursuant to the Cuban Assets...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-08-06

...., Malta) (vessel) [CUBA]. 3. ALAMINOS (f.k.a. RUBY ISLANDS) (P32C3) General Cargo 15,088DWT 8,909GRT Cyprus flag (Alaminos Shipping Co. Ltd.) (vessel) [CUBA]. 4. CARIBBEAN PRINCESS (C4GL) General Cargo 24... (C4JO) General Cargo 24,106DWT 16,794GRT Cyprus flag (CARIBBEAN QUEEN SHIPPING (SDN)) (vessel) [CUBA]. 6...
Palaeointensity determinations, palaeodirections and magnetic properties of basalts from the Emperor seamounts

NASA Astrophysics Data System (ADS)

Carvallo, Claire; Özdemir, Özden; Dunlop, David J.

2004-01-01

We measured palaeodirections and palaeointensities by the Thellier method on 93 samples from three of the Emperor seamounts: 20 from Detroit seamount (81 Ma), 48 from Nintoku seamount (56 Ma) and 25 from Koko seamount (48 Ma). Reliable palaeodirections obtained from three lava flows on Nintoku seamount give an average palaeolatitude of 32.7°, which is different from the present-day latitude of Hawaii and supports the hypothesis of a moving hotspot. According to the selection criteria traditionally used in palaeointensity determination, 17 samples give a reliable result. The samples show a very wide variety in unblocking temperatures, revealing an important variation in titanium content and the oxidation state of titanomagnetites. In order to assess the reliability of the palaeofield recording in the accepted samples, we carried out measurements of saturation isothermal remanent magnetization at low temperature and thermomagnetic curves. We found Curie temperatures varying from 250 to 580 °C, not only between seamounts but even within one lava flow. Thermomagnetic curves enabled us to identify titanomaghemite in several lava flows. After rejecting the results from samples showing evidence of maghemitization, only four samples, all from Nintoku seamount, can be considered as truly reliable. The palaeointensity values range between 34.2 and 36.9 μT. The low virtual axial dipole moment (VADM) values calculated from the palaeofield values are consistent with the most reliable VADM estimates in this time range and they are very close to the average VADM in the 0.3-300 Ma time interval.
Detrital and early chemical remanent magnetization in redbeds and their rock magnetic signature: Zicapa Formation, southern Mexico

NASA Astrophysics Data System (ADS)

Sierra-Rojas, Maria Isabel; Molina-Garza, Roberto Stanley

2018-06-01

Poles from continental redbeds are a large fraction of the world's palaeomagnetic database. Nonetheless, the time of acquisition and origin of the remanent magnetization of redbeds has been long debated. We report palaeomagnetic data, rock magnetic data and microscope observations for Lower Cretaceous redbeds in southern Mexico. These data allow us to discriminate between the hysteresis properties of remanent magnetizations of detrital and chemical origin, and to establish the early origin of a chemical remanence. Red sandstones of the Zicapa Formation contain a multicomponent remanence revealed by thermal demagnetization, and consisting of three stable components with partially overlapping laboratory unblocking temperatures of <250 °C, ˜300 to ˜500 °C and >600 °C, (low, intermediate and high temperature, respectively). They are interpreted as a viscous remanence residing in detrital magnetite, a chemical remanence residing in authigenic hematite and a depositional remanence residing in detrital hematite, respectively. The low-temperature component is nearly parallel to the recent dipole field. The tilt-corrected overall site means of the intermediate (chemical) and high temperature (depositional) components are indistinguishable (Dec = 282.0°, Inc = 12.4°, k = 13.33, α95 = 10.1°, N = 17, for the intermediate temperature; and Dec = 272.5°, Inc = 16.5°, k = 14.04, α95 = 11, N = 14, for the high temperature). Elongation/inclination analysis suggests that depositional and chemical components require applying an f = factor of approximately 0.4. Both of these components define a magnetic polarity zonation, but the polarity of the chemical and detrital components may or may not be the same. The chemical remanence coincides, more often than not, with the polarity of the depositional remanence of the overlying (younger) strata, suggesting a delay in remanence acquisition of tens to a few hundred ka for the chemical component. Pigmentary and detrital haematite were recognized with microscopic observations. The particle size of haematite ranges from approximately 10 to 300 μm for detrital haematite (martite, specularite and laterite), and from ca. 0.2 to 1 μm for pigmentary haematite flakes. The IRM of these rocks can be modelled with components of low coercivity (H1/2 between 5 and 10 mT interpreted as detrital magnetite), and components of a wide coercivity range (prevailing H1/2 from ˜400 to 600 mT interpreted as haematite). Hysteresis ratios show a systematic correlation with demagnetization behaviour, with lower Hcr/Hc values and higher Mrs/Ms values for samples with a dominant chemical component, than form samples with a significant (>40 per cent) depositional component.
Paleomagnetic reconstruction of Late Cretaceous structures along the Midelt-Errachidia profile (Morocco). Tectonic implications.

NASA Astrophysics Data System (ADS)

Torres López, Sara; José Villalain, Juan; Casas, Antonio; El ouardi, Hmidou; Moussaid, Bennacer; Ruiz-Martínez, Vicente Carlos

2017-04-01

Remagnetization data are used in this work to obtain the palinspastic reconstruction at 100 (Ma) of one of the most studied profiles of the Central High Atlas: the Midelt-Errachidia cross-section (Morocco). Previous studies in the area on syn-rift sedimentary rocks of subsiding basins have revealed that the Mesozoic sediments of this region acquired a pervasive remagnetization at the end of the Early Cretaceous. Fifty-eight sites (470 samples) corresponding to black limestones, marly limestones and marls, Early to Middle Jurassic in age, have been studied. Sites are distributed along a 70 km transect cutting across the basin and perpendicular to the main structures. The magnetic properties of samples are very regular showing very high NRM. Thermal and AF demagnetization showed a single stable paleomagnetic component with unblocking temperatures and coercivities spectra of 300-475°C and 20-100 mT respectively. This characteristic remanent magnetization (ChRM) showed systematically normal polarity suggesting a widespread remagnetization. In spite of the good outcrops and the relatively well-constrained structure of the High Atlas, there are many tectonic problems still unsolved, as the controversial existence of intra-Mesozoic deformation episodes. The restoration of paleomagnetic vectors to the remagnetization acquisition stage (100 Ma) allows to determine the dip of the beds during this period and, thereby, to obtain a reconstruction of structures during that time. This reconstruction accounts for the relative contribution of Mesozoic transpressional/transtrenssional movements vs. Cenozoic compression to the present-day dip. The results obtained indicate that these structures have undergone different degrees of pre-late Cretaceous deformation and were re-activated during the Cenozoic compression to finally acquire their present-day geometry.
Magnetic tape user guide

NASA Technical Reports Server (NTRS)

Evans, A. B.; Lee, L. L.

1985-01-01

This User Guide provides a general introduction to the structure, use, and handling of magnetic tapes at Langley Research Center (LaRC). The topics covered are tape terminology, physical characteristics, error prevention and detection, and creating, using, and maintaining tapes. Supplementary documentation is referenced where it might be helpful. The documentation is included for the tape utility programs, BLOCK, UNBLOCK, and TAPEDMP, which are available at the Central Scientific Computing Complex at LaRC.
Fluctuation of Ultrafiltration Coefficient of Hemodialysis Membrane During Reuse

NASA Astrophysics Data System (ADS)

Arif, Idam; Christin

2010-12-01

Hemodialysis treatment for patient with kidney failure is to regulate body fluid and to excrete waste products of metabolism. The patient blood and the dialyzing solution (dialysate) are flowed counter currently in a dialyzer to allow volume flux of fluid and diffusion of solutes from the blood to the dialysate through a semipermiable membrane. The volume flux of fluid depends on the hydrostatic and the osmotic pressure difference between the blood and the dialysate. It also depends on the membrane parameter that represents how the membrane allows the fluid and the solutes to move across as a result of the pressure difference, known as the ultrafiltration coefficient Kuf. The coefficient depends on the number and the radius of membrane pores for the movement of the fluids and the solutes across the membrane. The measured membrane ultrafiltration coefficient of reused dialyzer shows fluctuation between one uses to another without any significant trend of change. This indicates that the cleaning process carried out before reuse does not cause perfect removal of clots that happen in the previous use. Therefore the unblocked pores are forced to work hardly to obtain targeted volume flux in a certain time of treatment. This may increase the unblocked pore radius. Reuse is stopped when there is indication of blood leakage during the hemodialysis treatment.
Orogenic remagnetizations and paleomagnetic analysis of fault propagation folds in Lower Carboniferous carbonates, Northern Rockies, NW Montana and SW Alberta

NASA Astrophysics Data System (ADS)

Zechmeister, M. S.; O'Brien, V. J.; Elmore, R. D.; Evans, M. A.

2006-12-01

Results from paleomagnetic analysis of Lower Carboniferous carbonates in the Sawtooth Range, northwestern Montana and the Livingstone range in Southwestern Alberta are presented. Paleomagnetic cores were collected from both limbs of four fault propagation folds, one at Swift Dam in MT as well as one along Green Creek and two along Oldman River in Alberta. The Swift Dam Fold is in the Madison Group and contains a widespread characteristic remanent magnetization (ChRM) that resides in magnetite with southerly declinations and moderately steep up inclinations. A tilt test reveals a synfolding ChRM, and the paleopole suggests remanence acquisition in the Cretaceous to Early Tertiary. This result contrasts with results from another fold in MT, the Teton anticline, which is a buckle fold where a similar ChRM is pretilting. The reason for the differences in the fold test results are under investigation. The ChRM is not thermoviscous in origin based on a comparison of unblocking temperature with the low burial temperatures and is interpreted as a chemical remanent magnetization (CRM). Preliminary data from the folds in Livingstone Range suggest a similar ChRM in the organic rich lithologies of the Livingstone, Banff and Mount Head formations. Tilt test results for the fault propagation folds in Alberta will be presented as well as a discussion on the origin of orogenic remagnetizations.
Bayesian Localization and Mapping Using GNSS SNR Measurements

DTIC Science & Technology

2014-05-01

Bayesian Localization and Mapping Using GNSS SNR Measurements Jason T. Isaacs1, Andrew T. Irish1, François Quitin2, Upamanyu Madhow1, and João P...Hespanha1 Abstract— In urban areas, GNSS localization quality is often degraded due to signal blockage and multi-path reflections. When several GNSS ...signals are blocked by buildings, the remaining unblocked GNSS satellites are typically in a poor geometry for localization (nearly collinear along the

Paleomagnetic and Anisotropy of Magnetic Susceptibility (AMS) Documentation of the Formation of Large-Scale Rheomorphic Structures in the 2.06 Ma Huckleberry Ridge Tuff, Eastern Idaho

NASA Astrophysics Data System (ADS)

Geissman, J. W.; Holm, D.; Harlan, S. S.

2006-12-01

In the Teton River Valley, east of Rexburg, Idaho, the ca. 2.06 Ma Huckleberry Ridge Tuff is about 130 m thick, exceedingly well-exposed, and displays large-scale (100-150 m+ amplitude) rheomorphic folds, with eutaxitic fabrics that are parallel to inferred primary internal zonation (e.g. boundary between basal vitrophyre and overlying devitrified part of the pyroclastic deposit) as well as the basal contact with older deposits defining the fold geometries. One 150 m amplitude fold , is well-exposed on the north side of the valley about 2.5 km east of Teton Dam, has a NW trending fold axis and has a southwest limb that is overturned by about 45o. Samples were collected from 16 sites in this fold, on both limbs and the hinge area, to test the hypothesis that folding took place above maximum TRM blocking temperatures (about 580C). Progressive AF and thermal demagnetization both yield characteristic magnetizations of southwest to south-southwest declination and shallow inclination removed over a range of peak fields (typically between 20 and 80 mT) and laboratory unblocking temperatures (typically between 350 and 580C). The preliminary determination of an in situ mean based on the 16 sites is about D = 215°, I = -5°, a95= 5°, N = 16 site means). The direction of this ChRM is statistically indistinguishable from that reported by previous studies of the tuff (e.g. Reynolds, 1977, JGR; Byrd et al., 1994, JGR). The trend of the fold axis is orthogonal to this declination; the paleomagnetic fold test applied to these data is negative, with k values continuously decreasing upon unfolding, thus indicating that the entire structure in the tuff formed after the well-developed compaction fabric was acquired, at a temperature above maximum blocking temperatures of the ChRM. Post-compaction, high temperature deformation is consistent with field evidence indicating plastic secondary deformation of much of the tuff prior to devitrification. Rapid strain rates probably contributed to the formation of brittle features in the uppermost parts of the tuff (joints and fissures). AMS fabrics, at the site level, are typically very well-defined, with AMS foliations roughly parallel to compaction fabric, with K1 (maximum principal susceptibility) axes typically directed in a southwest-northeast orientation.
Effects of crystallite size on the structure and magnetism of ferrihydrite

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

Wang, Xiaoming; Zhu, Mengqiang; Koopal, Luuk K.

2015-12-15

The structure and magnetic properties of nano-sized (1.6 to 4.4 nm) ferrihydrite samples are systematically investigated through a combination of X-ray diffraction (XRD), X-ray pair distribution function (PDF), X-ray absorption spectroscopy (XAS) and magnetic analyses. The XRD, PDF and Fe K-edge XAS data of the ferrihydrite samples are all fitted well with the Michel ferrihydrite model, indicating similar local-, medium- and long-range ordered structures. PDF and XAS fitting results indicate that, with increasing crystallite size, the average coordination numbers of Fe–Fe and the unit cell parameter c increase, while Fe2 and Fe3 vacancies and the unit cell parameter a decrease.more » Mössbauer results indicate that the surface layer is relatively disordered, which might have been caused by the random distribution of Fe vacancies. These results support Hiemstra's surface-depletion model in terms of the location of disorder and the variations of Fe2 and Fe3 occupancies with size. Magnetic data indicate that the ferrihydrite samples show antiferromagnetism superimposed with a ferromagnetic-like moment at lower temperatures (100 K and 10 K), but ferrihydrite is paramagnetic at room temperature. In addition, both the magnetization and coercivity decrease with increasing ferrihydrite crystallite size due to strong surface effects in fine-grained ferrihydrites. Smaller ferrihydrite samples show less magnetic hyperfine splitting and a lower unblocking temperature (T B) than larger samples. The dependence of magnetic properties on grain size for nano-sized ferrihydrite provides a practical way to determine the crystallite size of ferrihydrite quantitatively in natural environments or artificial systems.« less
Binary moving-blocker-based scatter correction in cone-beam computed tomography with width-truncated projections: proof of concept.

PubMed

Lee, Ho; Fahimian, Benjamin P; Xing, Lei

2017-03-21

This paper proposes a binary moving-blocker (BMB)-based technique for scatter correction in cone-beam computed tomography (CBCT). In concept, a beam blocker consisting of lead strips, mounted in front of the x-ray tube, moves rapidly in and out of the beam during a single gantry rotation. The projections are acquired in alternating phases of blocked and unblocked cone beams, where the blocked phase results in a stripe pattern in the width direction. To derive the scatter map from the blocked projections, 1D B-Spline interpolation/extrapolation is applied by using the detected information in the shaded regions. The scatter map of the unblocked projections is corrected by averaging two scatter maps that correspond to their adjacent blocked projections. The scatter-corrected projections are obtained by subtracting the corresponding scatter maps from the projection data and are utilized to generate the CBCT image by a compressed-sensing (CS)-based iterative reconstruction algorithm. Catphan504 and pelvis phantoms were used to evaluate the method's performance. The proposed BMB-based technique provided an effective method to enhance the image quality by suppressing scatter-induced artifacts, such as ring artifacts around the bowtie area. Compared to CBCT without a blocker, the spatial nonuniformity was reduced from 9.1% to 3.1%. The root-mean-square error of the CT numbers in the regions of interest (ROIs) was reduced from 30.2 HU to 3.8 HU. In addition to high resolution, comparable to that of the benchmark image, the CS-based reconstruction also led to a better contrast-to-noise ratio in seven ROIs. The proposed technique enables complete scatter-corrected CBCT imaging with width-truncated projections and allows reducing the acquisition time to approximately half. This work may have significant implications for image-guided or adaptive radiation therapy, where CBCT is often used.
Binary moving-blocker-based scatter correction in cone-beam computed tomography with width-truncated projections: proof of concept

NASA Astrophysics Data System (ADS)

Lee, Ho; Fahimian, Benjamin P.; Xing, Lei

2017-03-01

This paper proposes a binary moving-blocker (BMB)-based technique for scatter correction in cone-beam computed tomography (CBCT). In concept, a beam blocker consisting of lead strips, mounted in front of the x-ray tube, moves rapidly in and out of the beam during a single gantry rotation. The projections are acquired in alternating phases of blocked and unblocked cone beams, where the blocked phase results in a stripe pattern in the width direction. To derive the scatter map from the blocked projections, 1D B-Spline interpolation/extrapolation is applied by using the detected information in the shaded regions. The scatter map of the unblocked projections is corrected by averaging two scatter maps that correspond to their adjacent blocked projections. The scatter-corrected projections are obtained by subtracting the corresponding scatter maps from the projection data and are utilized to generate the CBCT image by a compressed-sensing (CS)-based iterative reconstruction algorithm. Catphan504 and pelvis phantoms were used to evaluate the method’s performance. The proposed BMB-based technique provided an effective method to enhance the image quality by suppressing scatter-induced artifacts, such as ring artifacts around the bowtie area. Compared to CBCT without a blocker, the spatial nonuniformity was reduced from 9.1% to 3.1%. The root-mean-square error of the CT numbers in the regions of interest (ROIs) was reduced from 30.2 HU to 3.8 HU. In addition to high resolution, comparable to that of the benchmark image, the CS-based reconstruction also led to a better contrast-to-noise ratio in seven ROIs. The proposed technique enables complete scatter-corrected CBCT imaging with width-truncated projections and allows reducing the acquisition time to approximately half. This work may have significant implications for image-guided or adaptive radiation therapy, where CBCT is often used.
Comparison of Laser Doppler and Laser-Assisted Indocyanine Green Angiography Prediction of Flap Survival in a Novel Modification of the McFarlane Flap.

PubMed

Fourman, Mitchell Stephen; Gersch, Robert P; Phillips, Brett T; Nasser, Ahmed; Rivara, Andrew; Verma, Richa; Dagum, Alexander B; Rosengart, Todd K; Bui, Duc T

2015-07-01

The McFarlane rat ischemic dorsal skin flap model has been commonly used for clinical vector studies, as well as the testing of noninvasive diagnostics. However, variability of this model secondary to flap contact with the wound bed has led many to question its validity. Here we present a novel modification to the McFarlane skin flap using sterile silicone. We also use this model to test the prognostic efficacy of laser-assisted indocyanine green (ICG) angiography and laser Doppler imaging (LDI). A 3 × 9-cm dorsal skin flap with a cranially based pedicle was created, centered 1 cm distal to the scapulae. The flap was undermined, and in one of the 2 groups, a sterile silicone sheet was placed onto the wound bed. All flaps were then reapproximated with sutures 1-cm intervals. Clinical assessment and perfusion imaging was performed immediately postoperative, and at 24, 48, and 72 hours postsurgery. Postoperative day 7 clinical assessment was obtained before euthanasia. A comparative study using silicone blocked versus unblocked models (n = 6 per group) showed that, clinically, both models had equivalent flap survival [8.5 (0.913) vs 9.5 (1.01) cm]. However, a statistically significant increase in perfusion in the mid-third of unblocked models was observed on POD3 [20.28% (2.7%) vs blocked 13.45% (2.5%), P < 0.05], with a similar increase in the distal third on POD7 [18.73% (2.064%) vs 10.91% (4.19%), P < 0.05]. A prognostic study comparing LDI and ICG angiography prediction of POD7 survival at early time points (n = 10) found that LDI underpredicted flap survival at early time points [84.2% (12.03%) on POD0, 87.35% (16.11%) on POD1]. In contrast, ICG was more proficient [100.1% (10.1%) on POD0]. We present a modification of the McFarlane skin flap model that results in similar clinical results, but with a noted reduction in perfusion inconsistencies noted in unblocked models. The ICG angiography is superior to LDI in predicting POD7 flap necrosis within the first 48 hours postinjury. Future work will focus on histologic validation of our model, and vector efficacy testing.
Highly efficient peptide formation from N-acetylaminoacyl-AMP anhydride and free amino acid

NASA Technical Reports Server (NTRS)

Mullins, D. W., Jr.; Lacey, J. C., Jr.

1983-01-01

The kinetics of formation of the N-blocked dipeptide, N-acetylglycylglycine, from N-acetylglycyl adenylate anhydride and glycine in aqueous solution at 25 C, and at various PH's are reported. The reaction is of interest in that over a physiologically relevant pH range (6-8), peptide synthesis proceeds more rapidly than hydrolysis, even at those pH's at which this compound becomes increasingly susceptible to base-catalyzed hydrolysis. Under similar conditions, the corresponding unblocked aminoacyl adenylate anhydrides are considerably more unstable, and undergo appreciable hydrlysis in the presence of free amino acid. Because N-blocked aminoacyl adenylate anhydrides serve as model compounds of peptidyl adenylate anhydrides, these results suggest that primitive amino acid polymerization systems may have operated by cyclic reactivation of the peptidyl carboxyl group, rather than that of the incoming amino acid.
The Role of Early-Phase Transmission in the Spread of Yersinia pestis

PubMed Central

EISEN, REBECCA J.; DENNIS, DAVID T.; GAGE, KENNETH L.

2015-01-01

Early-phase transmission (EPT) of Yersinia pestis by unblocked fleas is a well-documented, replicable phenomenon with poorly defined mechanisms. We review evidence demonstrating EPT and current knowledge on its biological and biomechanical processes. We discuss the importance of EPT in the epizootic spread of Y. pestis and its role in the maintenance of plague bacteria in nature. We further address the role of EPT in the epidemiology of plague. PMID:26336267
Portable conduit retention apparatus for releasably retaining a conduit therein

DOEpatents

Metzger, Richard H.

1998-01-01

Portable conduit retention apparatus for releasably retaining a conduit therein. The apparatus releasably retains the conduit out of the way of nearby personnel and equipment. The apparatus includes a portable support frame defining a slot therein having an open mouth portion in communication with the slot for receiving the conduit through the open mouth portion and into the slot. A retention bar is pivotally connected to the support frame adjacent the mouth portion for releasably retaining the conduit in the slot. The retention bar freely pivots to a first position, so that the mouth portion is unblocked in order that the conduit is received through the mouth portion and into the slot. In addition, the retention bar freely pivots to a second position, so that the mouth portion is blocked in order that the conduit is retained in the slot. The conduit is released from the slot by pivoting the retention bar to the first position to unblock the mouth portion and thereafter manipulating the conduit from the slot and through the mouth portion. The apparatus may further include a mounting member attached to the support frame for mounting the apparatus on a vertical support surface. Another embodiment of the apparatus includes a shoe assembly of predetermined weight removably connected to the support frame for resting the apparatus on a floor in such a manner that the apparatus is substantially stationary on the floor.
Oman's low latitude "Snowball Earth" pole revisited: Late Cretaceous remagnetisation of Late Neoproterozoic carbonates in Northern Oman

NASA Astrophysics Data System (ADS)

Rowan, C. J.; Tait, J.

2010-12-01

Glaciogenic diamictites and associated ‘cap’ carbonates within the Neoproterozoic Huqf Supergroup of Oman record a period of extreme, possibly global, glaciations between 750-635 Ma (the "Snowball Earth"). We have performed high-resolution paleomagnetic sampling of two sections through ~635 Ma cap carbonates in the Jebel Akhdar region of northern Oman. Stepwise thermal demagnetisation reveals a low temperature component carried by goethite, and a high temperature component carried by haematite, that are both aligned with the modern dipole field direction. Occasional reversed polarity directions antipodal to the present day field indicate pervasive weathering of these outcrops over timescales of at least 1 Ma. Between these two overprints an intermediate component with typical unblocking temperatures of 300-550 C, probably carried by magnetite, can also be isolated in most samples. A robust fold test clearly demonstrates that this component was acquired after Paleozoic folding of the carbonates, and was most likely acquired during exhumation associated with emplacement of the Semail ophiolite during the Late Cretaceous (95-68 Ma). In geographic co-ordinates, the intermediate component has an almost horizontal NNW or SSE direction, similar to directions previously reported from outcrops of the ophiolite close to the Jebel Akhdar region, and from thermally altered basement rocks in the the Saih Hatat window further to the east [Feinberg et al. 1999]. Hints of an older, Permian, remagnetisation of the carbonates, which is also observed in the Saih Hatat basement rocks, have also produced a false polarity stratigraphy in one of the sampled sections. Our results contrast with the previously reported low latitude pole from the Huqf Supergroup [Kilner et al., 2005], which was considered to be amongst the more reliable paleomagnetic data supporting glaciations extending to low latitudes during the late Neoproterozoic. However, this interpretation was made on the basis of lower resolution sampling of only shallowly dipping sequences, and it is clear that this low-latitude pole was calculated from the same magnetic component that we have definitively shown to be a later remagnetisation. The paleolatitude of Oman during the Late Neoproterozoic glaciations therefore remains unconstrained, although paleomagnetic analysis of volcanic and sedimentary units in the Huqf Supergroup that bracket the glacial formations may yet yield a primary remanence.
The tectonic and geomagnetic significance of paleomagnetic observations from volcanic rocks from central Afar, Africa

NASA Astrophysics Data System (ADS)

Acton, Gary D.; Tessema, Abera; Jackson, Michael; Bilham, Roger

2000-08-01

Deformation throughout Afar over the past 2 myr has been characterized by widespread and intense crustal fragmentation that results from inhomogeneous extension across the region. In eastern Afar, this situation has evolved to localized extension associated with the westward propagation of the Gulf of Aden/Gulf of Tadjurah seafloor spreading system into the Asal-Ghoubbet Rift. During the gradual process of rift propagation and localization, crustal blocks in eastern Afar sustained clockwise rotations of ˜11°. To better understand the processes of rift propagation and localization and how they affect the rest of Afar, we have collected and analyzed over 400 oriented paleomagnetic samples from 67 lava flows from central and southern Afar. Unlike eastern Afar, the mean paleomagnetic direction from central Afar indicates that vertical-axis rotations are statistically insignificant (3.6°±4.4°), though small clockwise rotations (<8°) are permitted. Thus, propagation and localization in central Afar have not had the same influence in causing crustal block rotations or, perhaps more likely, have not reached the same stage of evolution as seen in eastern Afar. In addition, several of the lava flows record intriguing geomagnetic field behavior associated with polarity transitions, excursions, or large secular variation events. Interestingly, the transitional or anomalous virtual geomagnetic poles (VGPs) tend to cluster in two nearly antipodal regions, one in the northern Pacific Ocean and the other in the southwest Indian Ocean. One lava flow has recorded both of the antipodal transitional components, with the two components residing in magnetic minerals with unblocking temperatures above and below ˜500°C, respectively. Reheating and partial remagnetization by the overlying flow cannot explain either of the transitional directions because both differ significantly from that of the reversely magnetized overlying flow. The high-temperature component gives a VGP in the northern Pacific, whereas the lower-temperature component gives a nearly antipodal VGP south of Cape Town, South Africa. Hence, the configuration of the geomagnetic field appears to have jumped nearly instantaneously from a northern-hemisphere transitional state to a southern-hemisphere one during this normal-to-reverse polarity transition.
Palaeomagnetic, rock-magnetic and mineralogical investigations of metadolerites from Western Svalbard : A preliminary report

NASA Astrophysics Data System (ADS)

Michalski, Krzysztof; Nejbert, Krzysztof; Domańska-Siuda, Justyna; Manby, Geoffrey

2014-05-01

A group of 42 independently oriented palaeomagnetic samples from 7 sites located in central part of the West Spitsbergen Thrust and Fault Belt has been investigated. The samples were collected from 5 distinct metadolerite sheets intruded into the Proterozoic - Lower Paleozoic metamorphic complex of Western Oscar II Land (Western Svalbard Caledonian Terrane - Harland, 1997 division). All analyzed metadolerite samples were metamorphosed under greenschist facies metamorphism. The metamorphic assemblage consist of hornblende, biotite, actinolite, chlorite, epidote, stilpnomelane, titanite, albite, and quartz. Calcite, associated with pyrrhotite, pyrite chalcopyrite, sphalerite, and covellite, that occurs as irregular intergrowths or thin veins, document high activity of H2O-CO2-rich fluids during metamorphism. Primary magmatic phases represented by clinopyroxene occur rarely, and only in thick metadolerite dykes. Accessory oxides change their mineralogical and chemical composition during metamorphism. In all examined samples primary Ti-magnetite and oxy-exsolved hematite break-down completely into titanite or have been dissolved. The ilmenite are also replaced by titanite, but in metadolerites at contact with host metapelites, slightly altered ilmenite grains with preserved hematite exsolution were documented. Basing on mineralogical observations it should be expected that metamorphic processes have almost completely reset the paleomagnetic data record from the time of dolerite crystallization. This stage can document only rare hematite oxy-exsolution preserved within ilmenite, and presumably small inclusion of magnetite still preserved within unaltered clinopyroxene. The paleomagnetic record of metamorphic stage is probably recorded by pyrrhotite, hematite, goethite, and late Ti-free magnetite that can grow during breakdown of pyrrhotite to pyrite (Ramdohr. 1980). The NRM (Natural Remanent Magnetisation) intensities of the palaeomagnetic samples exceed the minimum 10 mA/m. The first AF/thermal demagnetizations have revealed a stable NRM structure. ChRM (Characteristic Remanent Magnetisation) components can be extracted precisely from Zijderveld diagrams (precision parameter - ASD max. 10º). The following magnetic procedures have been applied to identify the ferromagnetic carriers of the samples: SIRM (saturation isothermal remanent magnetization) decay curves (procedure after Kadziałko-Hofmokl & Kruczyk, 1976) and the three-component IRM (isothermal remanent magnetization) procedure described by Lowrie (1990). Experimental work has revealed the dominance of pyrrhotite and magnetite phases as carriers with soft-medium coercivity (samples are saturated in 0.2-0.4 T) and distinct unblocking temperatures around 320-350 ºC and 575-600 ºC respectively. Presented study is the part of PALMAG project 2012-2015: "Integration of palaeomagnetic, isotopic and structural data to understand Svalbard Caledonian Terranes assemblage" (see also Michalski et al. 2012), funded by Polish National Science Centre. References: HARLAND,W.B. 1997. The Geology of Svalbard. Geological Society of London, Memoir 17, 521 pp. KĄDZIOŁKO-HOFMOKL,M. & KRUCZYK,J. 1976. Complete and partial self-reversal of natural remanent magnetization of basaltic rocks from Lower Silesia, Poland. Pure and Applied Geophysics 110, 2031-40. LOWRIE,W. 1990. Identification of ferromagnetic minerals in a rock by coercivity and unblocking temperature properties. Geophysical Research Letters 17, 159-62. MICHALSKI,K., LEWANDOWSKI,M., MANBY,G.M. 2012. New palaeomagnetic, petrographic and 40Ar/39Ar data to test palaeogeographic reconstructions of Caledonide Svalbard. Cambridge University Press. Geological Magazine 149 (4), 696-721. RAMDOHR,P. 1980. The ore minerals and their intergrowths. Pergamon Press, Oxford.
Paleomagnetism of Late Jurassic to Early Cretaceous red beds from the Cardamom Mountains, southwestern Cambodia: Tectonic deformation of the Indochina Peninsula

NASA Astrophysics Data System (ADS)

Tsuchiyama, Yukiho; Zaman, Haider; Sotham, Sieng; Samuth, Yos; Sato, Eiichi; Ahn, Hyeon-Seon; Uno, Koji; Tsumura, Kosuke; Miki, Masako; Otofuji, Yo-ichiro

2016-01-01

Late Jurassic to Early Cretaceous red beds of the Phuquoc Formation were sampled at 33 sites from the Sihanoukville and Koah Kong areas of the Phuquoc-Kampot Som Basin, southwestern Cambodia. Two high-temperature remanent components with unblocking temperature ranging 650°-670 °C and 670-690 °C were identified. The magnetization direction for the former component (D = 5.2 °, I = 18.5 ° with α95 = 3.1 ° in situ) reveals a negative fold test that indicates a post-folding secondary nature. However, the latter component, carried by specular hematite, is recognized as a primary remanent magnetization. A tilt-corrected mean direction of D = 43.4 °, I = 31.9 ° (α95 = 3.6 °) was calculated for the primary component at 11 sites, corresponding to a paleopole of 47.7°N, 178.9°E (A95 = 3.6 °). When compared with the 130 Ma East Asian pole, a southward displacement of 6.0 ° ± 3.5 ° and a clockwise rotation of 33.1 ° ± 4.0 ° of the Phuquoc-Kampot Som Basin (as a part of the Indochina Block) with respect to East Asia were estimated. This estimate of the clockwise rotation is ∼15° larger than that of the Khorat Basin, which we attribute to dextral motion along the Wang Chao Fault since the mid-Oligocene. The comparison of the herein estimated clockwise rotation with the counter-clockwise rotation reported from the Da Lat area in Vietnam suggests the occurrence of a differential tectonic rotation in the southern tip of the Indochina Block. During the southward displacement of the Indochina Block, the non-rigid lithosphere under its southern tip moved heterogeneously, while the rigid lithosphere under the Khorat Basin moved homogeneously.
Rock Magnetic Properties and Paleointensity Determinations of Basalts From the Emperor Seamounts

NASA Astrophysics Data System (ADS)

Carvallo, C.; Dunlop, D. J.; Ozdemir, O.

2002-12-01

Thellier-Thellier paleointensity experiments were carried out on sixty-six basaltic samples coming from three Emperor seamounts (Detroit, Nintoku and Koko) drilled during ODP Leg 197. Seventeen samples yielded reliable results. One sample from Detroit Seamount (81 Ma) gives a VADM of 3.0+/-0.2x1022Am2. Ten samples from Nintoku (56 Ma) give VADMs between 1.6+/-0.1x1022 and 4.7+/-0.2x1022Am2. Six samples from Koko seamount (44 Ma) give VADMs between 0.6+/-0.1x1022 and 1.8+/-0.1x1022Am2. Assuming that the accepted samples did not undergo any maghemitization, the generally low VADM values we measured are in agreement with other records of paleointensities in this time range. The low success rate was due to chemical changes during the heatings. Samples have a wide distribution of unblocking temperatures and bulk susceptibility variations during heating, revealing an important variation in oxidation state and titanium content with depth and between seamounts. Other rock magnetic properties such as low-temperature measurements and thermomagnetic curves also indicate that the magnetic composition of the basalt varies from almost pure magnetite to titanomagnetite (x=0.4) within the same hole. Identification of magnetic minerals is important in order to assess the reliability of paleointensity and paleomagnetic measurements. It might also provide some information on parameters such as cooling rate of the lava flows or alteration.
Portable conduit retention apparatus for releasably retaining a conduit therein

DOEpatents

Metzger, R.H.

1998-07-07

Portable conduit retention apparatus is described for releasably retaining a conduit therein. The apparatus releasably retains the conduit out of the way of nearby personnel and equipment. The apparatus includes a portable support frame defining a slot therein having an open mouth portion in communication with the slot for receiving the conduit through the open mouth portion and into the slot. A retention bar is pivotally connected to the support frame adjacent the mouth portion for releasably retaining the conduit in the slot. The retention bar freely pivots to a first position, so that the mouth portion is unblocked in order that the conduit is received through the mouth portion and into the slot. In addition, the retention bar freely pivots to a second position, so that the mouth portion is blocked in order that the conduit is retained in the slot. The conduit is released from the slot by pivoting the retention bar to the first position to unblock the mouth portion and thereafter manipulating the conduit from the slot and through the mouth portion. The apparatus may further include a mounting member attached to the support frame for mounting the apparatus on a vertical support surface. Another embodiment of the apparatus includes a shoe assembly of predetermined weight removably connected to the support frame for resting the apparatus on a floor in such a manner that the apparatus is substantially stationary on the floor. 6 figs.
Non-linearity of the collagen triple helix in solution and implications for collagen function.

PubMed

Walker, Kenneth T; Nan, Ruodan; Wright, David W; Gor, Jayesh; Bishop, Anthony C; Makhatadze, George I; Brodsky, Barbara; Perkins, Stephen J

2017-06-16

Collagen adopts a characteristic supercoiled triple helical conformation which requires a repeating (Xaa-Yaa-Gly) n sequence. Despite the abundance of collagen, a combined experimental and atomistic modelling approach has not so far quantitated the degree of flexibility seen experimentally in the solution structures of collagen triple helices. To address this question, we report an experimental study on the flexibility of varying lengths of collagen triple helical peptides, composed of six, eight, ten and twelve repeats of the most stable Pro-Hyp-Gly (POG) units. In addition, one unblocked peptide, (POG) 10unblocked , was compared with the blocked (POG) 10 as a control for the significance of end effects. Complementary analytical ultracentrifugation and synchrotron small angle X-ray scattering data showed that the conformations of the longer triple helical peptides were not well explained by a linear structure derived from crystallography. To interpret these data, molecular dynamics simulations were used to generate 50 000 physically realistic collagen structures for each of the helices. These structures were fitted against their respective scattering data to reveal the best fitting structures from this large ensemble of possible helix structures. This curve fitting confirmed a small degree of non-linearity to exist in these best fit triple helices, with the degree of bending approximated as 4-17° from linearity. Our results open the way for further studies of other collagen triple helices with different sequences and stabilities in order to clarify the role of molecular rigidity and flexibility in collagen extracellular and immune function and disease. © 2017 The Author(s).
Isolating the anisotropy of the characteristic remanence-carrying hematite grains: a first multispecimen approach

NASA Astrophysics Data System (ADS)

Bilardello, Dario

2015-08-01

Separating the contribution of different hematite coercivity grains to the magnetic fabric is a standing problem in rock magnetism because of the common occurrence of thermochemical alterations when measuring the anisotropy of thermal remanence. A technique that eliminates this bias is presented, which is useful when there is a need to separate the fabric of detrital from pigmentary hematite, for example. The method is based on stepwise thermal demagnetization of saturation isothermal remanent magnetizations (IRMs) applied orthogonally on three sister specimens, allowing calculation of the anisotropy tensor from the three components of each demagnetized IRM vector, avoiding the necessity of having to apply IRMs to thermochemically altered specimens. Vector subtraction allows determining the anisotropy tensor for specific unblocking-temperature ranges. The anisotropies of the pigmentary, specular and total hematite of the Mauch Chunk Formation red beds of Pennsylvania have been measured from an oriented block sample and results are compared to previous anisotropy measurements performed using the high-field anisotropy of isothermal remanence technique (hf-AIR), which measures total undifferentiated hematite. Experiments were conducted using non-saturating 1 T and fully saturating 5.5 T fields: both experimental sets seem capable of measuring the orientation of the specularite anisotropy principal axes, but 5.5 T are needed to capture the orientation of the higher coercivity pigmentary grains. The magnitudes of the principal axes, instead, are only faithfully measured using 5.5 T fields and yield somewhat higher anisotropies than those measured by hf-AIR. The fundamental requirement for this technique is homogeneous material among the three sister specimens, which is a significant limitation; homogeneity tests allow assessment of applicability of the method and reliability of the results.
Tectonic rotations south of the Bohemian Massif from palaeomagnetic directions of Permian red beds in Hungary

USGS Publications Warehouse

Marton, E.; Elston, D.P.

1987-01-01

Palaeomagnetic studies were carried out in Permian red beds of the Balaton Highlands, the Mecsek Mountains and the Bu??kk Mountains of Hungary. Statistically well defined directions were obtained from six localities in the Balaton Highlands and two localities in the Mecsek Mountains. No meaningful results were obtained from the Bu??kk Mountains. Three magnetic components were identified from red beds of the Balaton Highlands: (1) in haematite with a very high unblocking temperature (700??C), interpreted as a Permian magnetization (Dc= 79??, Ic=-11??, k = 24, ??95 = 13.6 ??), in six samples from three beds in a single locality (2) a secondary but ancient component residing mainly inmaghemite (D = 314??, I = 49??, k = 48, ??95 = 10.0??), in 84 samples from six localities with a within-locality scatter increasing on unfolding; and (3) a direction parallel to the present field (D = 7??, I = 62??, k = 46, ??95 = 7.7 ??), in nine samples from a single locality. For the Balaton Highlands, the component 1 direction agrees with directions obtained from Permian red beds and volcanics in the eastern part of the Southern and Eastern Alps and the Inner West Carpathians. All show large, apparent rotations relative to stable Europe since the Permian. Component 2 is of post-folding (post-Aptian) age. Its direction agrees with known Late Cretaceous directions from the Transdanubian Central Mountains, which also show significant counterclockwise rotation relative to stable Europe. The characteristic magnetization for the Mecsek Mountains resides in haematite and may be primary. The directions indicate only a slight net counterclockwise rotation of the Mecsek Mountains with respect to stable Europe since the Permian. ?? 1987.
Thermal Stability of a 4 Meter Primary Reflector for the Scanning Microwave Limb Sounder

NASA Technical Reports Server (NTRS)

Cofield, Richard; Kasl, Eldon P.

2010-01-01

We describe the fabrication and thermal-stability analysis and test of a composite demonstration model of the Scanning Microwave Limb Sounder (SMLS) primary reflector, having full 4m height and 1/3 the width planned for flight. SMLS is a space-borne heterodyne radiometer which will measure pressure, temperature and atmospheric constituents from thermal emission between 180 and 660 GHz. Current MLS instruments in low Earth orbit scan pencil-beam antennas (sized to resolve about one scale height) vertically over the atmospheric limb. SMLS, planned for the Global Atmospheric Composition Mission of the NRC Decadal Survey, adds azimuthal scanning for better horizontal and temporal resolution and coverage than typical orbit spacing provides. SMLS combines the wide scan range of the parabolic torus with unblocked offset Cassegrain optics. The resulting system is diffraction-limited in the vertical plane but highly astigmatic in the horizontal, having a beam aspect ratio [tilde operator]1:20. Symmetry about the nadir axis ensures that beam shape is nearly invariant over +/-65(white bullet) azimuth. The a feeds a low-noise SIS receiver whose FOV is swept over the reflector system by a small scanning mirror. Using finiteelement models of antenna reflectors and structure, we evaluate thermal deformations and the resulting optical performance for 4 orbital environments and isothermal soak. We compare deformations with photogrammetric measurements made during wide-range (ambient+[-97,+75](white bullet) C) thermal soak tests of the primary in a chamber. This range exceeds predicted orbital soak ranges by large factors, implying in-orbit thermal stability of 0.21(mu)m rms/(white bullet)C, which meets SMLS requirements.
Anomalously shallow inclination in middle-northern part of the South China block: palaeomagnetic study of Late Cretaceous red beds from Yichang area

NASA Astrophysics Data System (ADS)

Narumoto, Kazutoshi; Yang, Zhenyu; Takemoto, Kazuhiro; Zaman, Haider; Morinaga, Hayao; Otofuji, Yo-ichiro

2006-02-01

We present new palaeomagnetic results from Late Cretaceous red beds of the Paomagang Formation collected at 42 sites in the Yichang area (30.7°N, 111.7°E), middle-northern part of the South China Block. A high unblocking temperature component around 680°C was isolated from 26 sites by stepwise thermal demagnetization. Fold tests are positive at the 95 per cent confidence limit for 14 and 11 sites of the Paomagang and Wangdian areas, respectively. Normal and reversed polarity sequence found in the Wangdian area passed a reversal test at the 95 per cent confidence limit. The tilt-corrected mean direction for Yichang area is D= 3.8°, I= 23.3° (α95= 5.1°,N= 26), corresponding to a palaeopole at 71.5°N, 280.0°E with A95= 4.3°. Comparison with the expected inclination from the 80 Ma Eurasian APWP pole indicates a inclination flattening of 26.3°+/- 6.4°. Middle Cretaceous to Cenozoic NW-SE extension tectonics within the SCB contributes only 2.0° to the inclination flattening. While the massive samples of the Paomagang Formation show a moderate degree of anisotropy (1.017 < Pj < 1.086) and steeper inclination (I= 29.3°), the laminated samples, which form more than 75 per cent of the studied samples, show a higher degree of anisotropy (1.052 < Pj < 1.227) and shallower inclination value (I= 22.7°). A good correlation between remanence inclination and facies types indicates that depositional processes produced the observed shallow inclination in the Yichang area.
Magnetic history of Early and Middle Ordovician sedimentary sequence, northern Estonia

NASA Astrophysics Data System (ADS)

Plado, J.; Preeden, U.; Pesonen, L. J.; Mertanen, S.; Puura, V.

2010-01-01

Alternating field and thermal demagnetization of lime- and dolostones from the Lower and Middle Ordovician (Floian to Darriwilian stages) subhorizontally bedded sequences in NW and NE Estonia reveal two characteristic magnetization components (named P and S). The intermediate-coercivity (demagnetized at 30-60 mT, up to 300-350°C) reversed polarity component P (mean of Floian Stage: Dref = 147.8 +/- 10.8°, Iref = 65.8 +/- 5.4° combined mean of Dapingian and Darriwilian stages: Dref = 166.0 +/- 8.4°, Iref = 56.1 +/- 6.5°) is regarded as the primary remanence of early diagenetic (chemical) origin. On the Baltica's apparent polar wander path (APWP), the palaeopoles (Floian: Plat = 25.0°N, Plon = 50.8°E, K = 52.7, A95 = 7.2° Dapingian and Darriwilian: Plat = 11.4°N, Plon = 39.1°E, K = 33.8, A95 = 6.7°) are placed on the Lower and Middle Ordovician segment. The poles indicate that Estonia was located at southerly latitudes, decreasing with time (Floian: ~48°S Dapingian and Darriwilian: ~37°S), when the remanence was acquired. A high-coercivity and high-unblocking-temperature component S (mean of samples: Dref = 33.7 +/- 6.3°, Iref = 51.9 +/- 5.7°) that is regarded as a secondary remanence has both normal and reversed polarities. On the European APWP, its palaeopole (Plat = 52.5°N, Plon = 157.9°E, K = 38.9, A95 = 5.3°) gives middle to late Permian age. According to mineralogical (SEM and optical microscopy) and rock magnetic (three-component induced remnant magnetization) studies, component P is carried by magnetite (coexisting with glauconite) and component S by haematite. Magnetite is of chemical origin, formed in the course of early diagenesis and/or dolomitization. During the Permian continental period haematite, the carrier of component S, was likely precipitated from oxidizing meteoric fluids in the already existing or simultaneously formed pore space between the dolomite crystals.

Extensional vs. compressional deformation in the Central High Atlas salt province: A paleomagnetic approach

NASA Astrophysics Data System (ADS)

Calvín, P.; Casas-Sainz, A. M.; Villalaín, J. J.; Moussaid, B.

2018-06-01

In this paper we address the problem of the distinction between diapiric, salt-driven and compressional structures, using the outstanding example of the Central High Atlas (Morocco). A remagnetized component carried by magnetite has been isolated in 32 new paleomagnetic sites. It is characterized by: maximum unblocking temperatures around 450 °C, syn-folding behavior and normal polarity. These 33 mean paleomagnetic directions were analyzed together with other 68 from published works around the study area to construct a robust paleomagnetic dataset along a cross-section perpendicular to the main structures. The remagnetization direction (n: 100, Dec: 332.2°, Inc: 34.5°, η: 6.2°, ξ: 2.0°, A/n: 6.427°) and the paleo-dip of beds (the attitude of the beds at the remagnetization occurrence) were calculated through small circle methods. The remagnetization can be dated as ca. 100 Ma. Because of its occurrence between the extensional and compressional periods, this remagnetization offers the possibility of restore the basin to its pre-inversion geometry. Comparison between present-day and pre-inversion structure allows discriminating three different evolutionary patterns: (i) thrusted and welded salt-walls mainly structured during the extensional stage (Ikkou ridge) with steep limbs close to the salt-wall core. (ii) Jurassic salt-walls with weaker deformation, restricted to the areas adjacent to the structure (Tadaghmamt and Timedouine); in this case, Cenozoic compression is limited to welding of the salt-walls and buttressing of the sedimentary sequences against faults. (iii) salt-rollers gently initiated during the Jurassic (Toumliline diapir), thrusted during the Cenozoic compression. Results show the importance of salt tectonics both during extension and compression, as well as the control of the compressional features by the inherited extensional structures. The performed restorations prove that paleomagnetism is a useful, independent tool to obtain palinspastic restorations and to separate, and quantify, the imprint generated during the basinal stage from the inversional features.
An approach to multiobjective optimization of rotational therapy. II. Pareto optimal surfaces and linear combinations of modulated blocked arcs for a prostate geometry.

PubMed

Pardo-Montero, Juan; Fenwick, John D

2010-06-01

The purpose of this work is twofold: To further develop an approach to multiobjective optimization of rotational therapy treatments recently introduced by the authors [J. Pardo-Montero and J. D. Fenwick, "An approach to multiobjective optimization of rotational therapy," Med. Phys. 36, 3292-3303 (2009)], especially regarding its application to realistic geometries, and to study the quality (Pareto optimality) of plans obtained using such an approach by comparing them with Pareto optimal plans obtained through inverse planning. In the previous work of the authors, a methodology is proposed for constructing a large number of plans, with different compromises between the objectives involved, from a small number of geometrically based arcs, each arc prioritizing different objectives. Here, this method has been further developed and studied. Two different techniques for constructing these arcs are investigated, one based on image-reconstruction algorithms and the other based on more common gradient-descent algorithms. The difficulty of dealing with organs abutting the target, briefly reported in previous work of the authors, has been investigated using partial OAR unblocking. Optimality of the solutions has been investigated by comparison with a Pareto front obtained from inverse planning. A relative Euclidean distance has been used to measure the distance of these plans to the Pareto front, and dose volume histogram comparisons have been used to gauge the clinical impact of these distances. A prostate geometry has been used for the study. For geometries where a blocked OAR abuts the target, moderate OAR unblocking can substantially improve target dose distribution and minimize hot spots while not overly compromising dose sparing of the organ. Image-reconstruction type and gradient-descent blocked-arc computations generate similar results. The Pareto front for the prostate geometry, reconstructed using a large number of inverse plans, presents a hockey-stick shape comprising two regions: One where the dose to the target is close to prescription and trade-offs can be made between doses to the organs at risk and (small) changes in target dose, and one where very substantial rectal sparing is achieved at the cost of large target underdosage. Plans computed following the approach using a conformal arc and four blocked arcs generally lie close to the Pareto front, although distances of some plans from high gradient regions of the Pareto front can be greater. Only around 12% of plans lie a relative Euclidean distance of 0.15 or greater from the Pareto front. Using the alternative distance measure of Craft ["Calculating and controlling the error of discrete representations of Pareto surfaces in convex multi-criteria optimization," Phys. Medica (to be published)], around 2/5 of plans lie more than 0.05 from the front. Computation of blocked arcs is quite fast, the algorithms requiring 35%-80% of the running time per iteration needed for conventional inverse plan computation. The geometry-based arc approach to multicriteria optimization of rotational therapy allows solutions to be obtained that lie close to the Pareto front. Both the image-reconstruction type and gradient-descent algorithms produce similar modulated arcs, the latter one perhaps being preferred because it is more easily implementable in standard treatment planning systems. Moderate unblocking provides a good way of dealing with OARs which abut the PTV. Optimization of geometry-based arcs is faster than usual inverse optimization of treatment plans, making this approach more rapid than an inverse-based Pareto front reconstruction.
Injury rates during the 1988 US Olympic Team Trials for taekwondo.

PubMed Central

Zemper, E D; Pieter, W

1989-01-01

Injury rates were recorded during the 1988 US Olympic Team Trials for taekwondo involving 48 men and 48 women. The injury rate for men (12.74/100 athlete-exposures) was about 40 per cent higher than the rate for women (9.01/100 athlete-exposures). The foot and the head were the most frequently injured body parts. Contusions were the predominant type of injury, and concussions were recorded for both men and women. A large proportion (41 per cent) of the men's injuries were the result of receiving a blow from an unblocked attack. For the women the most common injury situation (40 per cent) was while attacking with a kick. For both men and women, 15 per cent of the reported injuries were time-loss injuries. The head injuries found in this study are discussed with reference to the high impact velocities and momentum levels generated during taekwondo kicking. Recommendations are made with regard to protective equipment testing and rule changes to reduce the possibility of cerebral injury. PMID:2620229
Comprehensive analysis of a Metabolic Model for lipid production in Rhodosporidium toruloides.

PubMed

Castañeda, María Teresita; Nuñez, Sebastián; Garelli, Fabricio; Voget, Claudio; Battista, Hernán De

2018-05-19

The yeast Rhodosporidium toruloides has been extensively studied for its application in biolipid production. The knowledge of its metabolism capabilities and the application of constraint-based flux analysis methodology provide useful information for process prediction and optimization. The accuracy of the resulting predictions is highly dependent on metabolic models. A metabolic reconstruction for R. toruloides metabolism has been recently published. On the basis of this model, we developed a curated version that unblocks the central nitrogen metabolism and, in addition, completes charge and mass balances in some reactions neglected in the former model. Then, a comprehensive analysis of network capability was performed with the curated model and compared with the published metabolic reconstruction. The flux distribution obtained by lipid optimization with Flux Balance Analysis was able to replicate the internal biochemical changes that lead to lipogenesis in oleaginous microorganisms. These results motivate the development of a genome-scale model for complete elucidation of R. toruloides metabolism. Copyright © 2018 Elsevier B.V. All rights reserved.
Simulation and analysis of traffic flow based on cellular automaton

NASA Astrophysics Data System (ADS)

Ren, Xianping; Liu, Xia

2018-03-01

In this paper, single-lane and two-lane traffic model are established based on cellular automaton. Different values of vehicle arrival rate at the entrance and vehicle departure rate at the exit are set to analyze their effects on density, average speed and traffic flow. If the road exit is unblocked, vehicles can pass through the road smoothly despite of the arrival rate at the entrance. If vehicles enter into the road continuously, the traffic condition is varied with the departure rate at the exit. To avoid traffic jam, reasonable vehicle departure rate should be adopted.
Radionuclide administration to nursing mothers: mathematically derived guidelines

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

Romney, B.M.; Nickoloff, E.L.; Esser, P.D.

We determined a formula to establish objective guidelines for the administration of radionuclides to nursing mothers. The formula is based on the maximum permissible dose to the infant's critical organ, serial measurements of breast milk activity, milk volume, and dose to the critical organ per microcurie in milk. Using worst-case assumptions, we believe that cessation of nursing for 24 hours after administration of technetium labeled radiopharmaceuticals is sufficient for safety. Longer-lived agents require greater delays. Iodine-123 radiopharmaceuticals are preferable to iodine-131 agents and should always be used when studying the unblocked thyroid.
Different Temporal Effects of Ebola Virus VP35 and VP24 Proteins on Global Gene Expression in Human Dendritic Cells.

PubMed

Ilinykh, Philipp A; Lubaki, Ndongala M; Widen, Steven G; Renn, Lynnsey A; Theisen, Terence C; Rabin, Ronald L; Wood, Thomas G; Bukreyev, Alexander

2015-08-01

Ebola virus (EBOV) causes a severe hemorrhagic fever with a deficient immune response, lymphopenia, and lymphocyte apoptosis. Dendritic cells (DC), which trigger the adaptive response, do not mature despite EBOV infection. We recently demonstrated that DC maturation is unblocked by disabling the innate response antagonizing domains (IRADs) in EBOV VP35 and VP24 by the mutations R312A and K142A, respectively. Here we analyzed the effects of VP35 and VP24 with the IRADs disabled on global gene expression in human DC. Human monocyte-derived DC were infected by wild-type (wt) EBOV or EBOVs carrying the mutation in VP35 (EBOV/VP35m), VP24 (EBOV/VP24m), or both (EBOV/VP35m/VP24m). Global gene expression at 8 and 24 h was analyzed by deep sequencing, and the expression of interferon (IFN) subtypes up to 5 days postinfection was analyzed by quantitative reverse transcription-PCR (qRT-PCR). wt EBOV induced a weak global gene expression response, including markers of DC maturation, cytokines, chemokines, chemokine receptors, and multiple IFNs. The VP35 mutation unblocked the expression, resulting in a dramatic increase in expression of these transcripts at 8 and 24 h. Surprisingly, DC infected with EBOV/VP24m expressed lower levels of many of these transcripts at 8 h after infection, compared to wt EBOV. In contrast, at 24 h, expression of the transcripts increased in DC infected with any of the three mutants, compared to wt EBOV. Moreover, sets of genes affected by the two mutations only partially overlapped. Pathway analysis demonstrated that the VP35 mutation unblocked pathways involved in antigen processing and presentation and IFN signaling. These data suggest that EBOV IRADs have profound effects on the host adaptive immune response through massive transcriptional downregulation of DC. This study shows that infection of DC with EBOV, but not its mutant forms with the VP35 IRAD and/or VP24 IRAD disabled, causes a global block in expression of host genes. The temporal effects of mutations disrupting the two IRADs differ, and the lists of affected genes only partially overlap such that VP35 and VP24 IRADs each have profound effects on antigen presentation by exposed DC. The global modulation of DC gene expression and the resulting lack of their maturation represent a major mechanism by which EBOV disables the T cell response and suggests that these suppressive pathways are a therapeutic target that may unleash the T cell responses during EBOV infection. Copyright © 2015, American Society for Microbiology. All Rights Reserved.
Is the blocking of drainage channels in upland peats an effective means of reducing DOC loss at the catchment scale?

NASA Astrophysics Data System (ADS)

Turner, Kate; Worrall, Fred

2010-05-01

Only 3% of the earths land surface is covered by peatland yet boreal and subarctic peatlands store approximately 15-30% of the World's soil carbon as peat (Limpens et al. 2008). In comparison British bogs store carbon equivalent to 20 years worth of national emissions. The loss of carbon from these areas in the form of dissolved organic carbon (DOC) is increasing and it is expected to have grown by up to 40% by 2018. Extensive drainage of UK peatlands has been associated with dehydration of the peat, an increase in water colour and a loss of carbon storage. It has been considered that the blocking of these drainage channels represents a means of peat restoration and a way of reducing DOC loss. This study aims to assess the effectiveness of this drain blocking at both an individual drain scale and at a larger catchment scale. Gibson et al. (2009) considered the effects of blocking at a solely individual drain scale finding that a 20% drop in DOC export was recorded post blocking however this decrease was due to a reduction in water yield rather than a reduction in DOC concentration with the concentration record showing no significant reduction. The effect of external parameters become more pronounced as the DOC record is examined at larger scales. The catchment is an open system and water chemistry will be influence by mixing with water from other sources. Also it is likely that at some point the drains will cut across slope leading to the flow of any highly coloured water down slope, bypassing the blockages, and entering the surface waters downstream. Degradation of DOC will occur naturally downstream due to the effects of light and microbial activity. There is, consequently, a need to examine the wider effects of drain blocking at a catchment scale to ensure that what is observed for one drain transfers to the whole catchment. A series of blocked and unblocked catchments were studied in Upper Teesdale, Northern England. Drain water samples were taken at least daily at nine localities. These sites were located such that individual drains could be monitored in the context of a larger catchment. Water table depth, flow and weather parameters were recorded along with the collection of runoff and soil water samples. A detailed sampling programme was undertaken in which a series of drains were studied in the 12 months prior to and post blocking. This approach has allowed the effects of blocking on the carbon budget, water balance and flow pathways to be considered. Results indicate that the blocking of zero order drainage channels leads to a decrease in DOC export on an individual drain scale. However, this is due to a reduction in water yield rather than concentration. Concentrations are seen to rise by a small yet statistically significant amount in blocked zero order streams. The effect at a larger scale is more complex. Annual export values in the unblocked control catchment show a rise from zero to first order streams indicating that water is being added to the system at this scale from external spatially variable sources. This pattern is also recognised in the blocked catchment. The DOC concentration record in blocked drains at this larger scale however indicated a reduction relative to the unblocked catchment. This reduction points to a change in flow pathways post blocking as highly coloured water re-navigates its way downstream. References: Gibson H, Worrall F, Burt TP, Adamson JK (2009) DOC budgets of drained peat catchments: implications for DOC production in peat soils, Hydrological Processes 23(13) 1901-1911 Limpens J (2008) Peatlands and the carbon cycle: from local processes to global implications- a synthesis, Biogeosciences 5 1475-1491
Estimation and modeling of electrofishing capture efficiency for fishes in wadeable warmwater streams

USGS Publications Warehouse

Price, A.; Peterson, James T.

2010-01-01

Stream fish managers often use fish sample data to inform management decisions affecting fish populations. Fish sample data, however, can be biased by the same factors affecting fish populations. To minimize the effect of sample biases on decision making, biologists need information on the effectiveness of fish sampling methods. We evaluated single-pass backpack electrofishing and seining combined with electrofishing by following a dual-gear, mark–recapture approach in 61 blocknetted sample units within first- to third-order streams. We also estimated fish movement out of unblocked units during sampling. Capture efficiency and fish abundances were modeled for 50 fish species by use of conditional multinomial capture–recapture models. The best-approximating models indicated that capture efficiencies were generally low and differed among species groups based on family or genus. Efficiencies of single-pass electrofishing and seining combined with electrofishing were greatest for Catostomidae and lowest for Ictaluridae. Fish body length and stream habitat characteristics (mean cross-sectional area, wood density, mean current velocity, and turbidity) also were related to capture efficiency of both methods, but the effects differed among species groups. We estimated that, on average, 23% of fish left the unblocked sample units, but net movement varied among species. Our results suggest that (1) common warmwater stream fish sampling methods have low capture efficiency and (2) failure to adjust for incomplete capture may bias estimates of fish abundance. We suggest that managers minimize bias from incomplete capture by adjusting data for site- and species-specific capture efficiency and by choosing sampling gear that provide estimates with minimal bias and variance. Furthermore, if block nets are not used, we recommend that managers adjust the data based on unconditional capture efficiency.
Kainate receptor pore‐forming and auxiliary subunits regulate channel block by a novel mechanism

PubMed Central

Brown, Patricia M. G. E.; Aurousseau, Mark R. P.; Musgaard, Maria; Biggin, Philip C.

2016-01-01

Key points Kainate receptor heteromerization and auxiliary subunits, Neto1 and Neto2, attenuate polyamine ion‐channel block by facilitating blocker permeation.Relief of polyamine block in GluK2/GluK5 heteromers results from a key proline residue that produces architectural changes in the channel pore α‐helical region.Auxiliary subunits exert an additive effect to heteromerization, and thus relief of polyamine block is due to a different mechanism.Our findings have broad implications for work on polyamine block of other cation‐selective ion channels. Abstract Channel block and permeation by cytoplasmic polyamines is a common feature of many cation‐selective ion channels. Although the channel block mechanism has been studied extensively, polyamine permeation has been considered less significant as it occurs at extreme positive membrane potentials. Here, we show that kainate receptor (KAR) heteromerization and association with auxiliary proteins, Neto1 and Neto2, attenuate polyamine block by enhancing blocker permeation. Consequently, polyamine permeation and unblock occur at more negative and physiologically relevant membrane potentials. In GluK2/GluK5 heteromers, enhanced permeation is due to a single proline residue in GluK5 that alters the dynamics of the α‐helical region of the selectivity filter. The effect of auxiliary proteins is additive, and therefore the structural basis of polyamine permeation and unblock is through a different mechanism. As native receptors are thought to assemble as heteromers in complex with auxiliary proteins, our data identify an unappreciated impact of polyamine permeation in shaping the signalling properties of neuronal KARs and point to a structural mechanism that may be shared amongst other cation‐selective ion channels. PMID:26682513
An efficient solution of real-time data processing for multi-GNSS network

NASA Astrophysics Data System (ADS)

Gong, Xiaopeng; Gu, Shengfeng; Lou, Yidong; Zheng, Fu; Ge, Maorong; Liu, Jingnan

2017-12-01

Global navigation satellite systems (GNSS) are acting as an indispensable tool for geodetic research and global monitoring of the Earth, and they have been rapidly developed over the past few years with abundant GNSS networks, modern constellations, and significant improvement in mathematic models of data processing. However, due to the increasing number of satellites and stations, the computational efficiency becomes a key issue and it could hamper the further development of GNSS applications. In this contribution, this problem is overcome from the aspects of both dense linear algebra algorithms and GNSS processing strategy. First, in order to fully explore the power of modern microprocessors, the square root information filter solution based on the blocked QR factorization employing as many matrix-matrix operations as possible is introduced. In addition, the algorithm complexity of GNSS data processing is further decreased by centralizing the carrier-phase observations and ambiguity parameters, as well as performing the real-time ambiguity resolution and elimination. Based on the QR factorization of the simulated matrix, we can conclude that compared to unblocked QR factorization, the blocked QR factorization can greatly improve processing efficiency with a magnitude of nearly two orders on a personal computer with four 3.30 GHz cores. Then, with 82 globally distributed stations, the processing efficiency is further validated in multi-GNSS (GPS/BDS/Galileo) satellite clock estimation. The results suggest that it will take about 31.38 s per epoch for the unblocked method. While, without any loss of accuracy, it only takes 0.50 and 0.31 s for our new algorithm per epoch for float and fixed clock solutions, respectively.
Analytical approaches to identify potential migrants in polyester-polyurethane can coatings.

PubMed

Louise Bradley, Emma; Driffield, Malcolm; Guthrie, James; Harmer, Nick; Thomas Oldring, Peter Kenneth; Castle, Laurence

2009-12-01

The safety of a polyester-polyurethane can coating has been assessed using a suite of complementary analytical methods to identify and estimate the concentrations of potential chemical migrants. The polyester was based on phthalic acids and aliphatic diols. The polyisocyanate cross-linking agent was 1-isocyanato-3-isocyanatomethyl-3,5,5-trimethyl cyclohexane homopolymer (IPDI) blocked with methylethylketone oxime (MEKO) to make a one-part formulation. The overall migrate, obtained using solvent extraction of cured films, comprised almost completely of 12 cyclic and one linear polyester oligomer up to molecular weight 800 and containing up to six monomer units. These 13 oligomers covered a total of 28 isomeric forms. Other minor components detected were plasticisers and surfactants as well as impurities present in the starting materials. There was no detectable residue of either the blocked isocyanate (<0.01 microg/dm(2)) used as the starting substance or the unblocked isocyanate (<0.02 microg/dm(2)). The level of extractable IPDI was used as an indicator of the completeness of cure in experimental coatings. These studies revealed that there was an influence of time, temperature and catalyst content. Polymerisation was also influenced by the additives used and by the ageing of the wet coating formulation over several months. These studies allow parameters to be specified to ensure that commercial production coatings receive a full cure giving low migration characteristics.
Palaeomagnetic constraints on the evolution of the Atlantis Massif oceanic core complex (Mid-Atlantic Ridge, 30°N)

NASA Astrophysics Data System (ADS)

Morris, Antony; Pressling, Nicola; Gee, Jeffrey; John, Barbara; MacLeod, Christopher

2010-05-01

Oceanic core complexes expose lower crustal and upper mantle rocks on the seafloor by tectonic unroofing in the footwalls of large-slip detachment faults. They represent a fundamental component of the seafloor spreading system at slow and ultraslow axes. For example, recent analyses suggest that detachment faults may underlie more than 50% of the Mid Atlantic Ridge (MAR) and may take up most of the overall plate divergence at times when magma supply to the ridge system is reduced. The most extensively studied oceanic core complex is Atlantis Massif, located at 30°N on the MAR. This forms an inside-corner bathymetric high at the intersection of the Atlantis Transform Fault and the MAR. The central dome of the massif exposes the corrugated detachment fault surface and was drilled during IODP Expedition 304/305. This sampled a 1.4 km faulted and complexly layered footwall section dominated by gabbroic lithologies with minor ultramafic rocks. The core (Hole U1309D) reflects the interplay between magmatism and deformation prior to, during, and subsequent to a period of footwall displacement and denudation associated with slip on the detachment fault. Palaeomagnetic analyses demonstrate that the gabbroic sequences at Atlantis Massif carry highly stable remanent magnetizations that provide valuable information on the evolution of the section. Thermal demagnetization experiments recover high unblocking temperature components of reversed polarity (R1) throughout the gabbroic sequences. In a number of intervals, however, the gabbros exhibit a complex remanence structure with the presence of intermediate temperature normal (N1) and lower temperature reversed (R2) polarity components, suggesting an extended period of remanence acquisition during different polarity intervals. Sharp break-points between different polarity components suggest that they were acquired by a thermal mechanism. There appears to be no correlation between remanence structure and either the igneous stratigraphy or the distribution of alteration in the core. Instead, the remanence data are more consistent with a model in which the lower crustal section acquired magnetizations of different polarity during a protracted cooling history spanning two geomagnetic reversals. Differences in the width of blocking temperature spectra between samples appear to control the number of components present; samples with narrow and high temperature spectra record only R1 components, whereas those with broader blocking temperature spectra record multicomponent (R1-N1 and R1-N1-R2) remanences. The common occurrence of detachment faults in slow and ultra-slow spreading oceanic crust suggests they accommodate a significant component of plate divergence. However, the sub-surface geometry of oceanic detachment faults remains unclear. Competing models involve either: (a) displacement on planar, low-angle faults with little tectonic rotation; or (b) progressive shallowing by rotation of initially steeply dipping faults as a result of flexural unloading (the "rolling-hinge" model). We resolve this debate using paleomagnetic remanences as a marker for tectonic rotation of the Atlantis Massif footwall. Previous ODP/IODP palaeomagnetic studies have been restricted to analysis of magnetic inclination data, since hard-rock core pieces are azimuthally unoriented and free to rotate in the core barrel. For the first time we have overcome this limitation by independently reorienting core pieces to a true geographic reference frame by correlating structures in individual pieces with those identified from oriented imagery of the borehole wall. This allows reorientation of paleomagnetic data and subsequent tectonic interpretation without the need for a priori assumptions on the azimuth of the rotation axis. Results indicate a 46°±6° counterclockwise rotation of the footwall around a MAR-parallel horizontal axis trending 011°±6°. This provides unequivocal confirmation of the key prediction of flexural, rolling-hinge models for oceanic core complexes, whereby faults initiate at higher dips and rotate to their present day low angle geometries.
[A very unusual pleural presentation].

PubMed

Vergne, F; Le Mao, R; Simonin, L; Descourt, R; Couturaud, F; Barnier, A; Tromeur, C

2018-05-01

Urinothorax refers to the presence of urine in the pleural space. Urinothorax is an infrequent and underdiagnosed pathology, with few cases reported, and these often suspected only with hindsight. It is usually a transudative pleural effusion. We report a case of urinothorax presenting as a purulent pleural effusion. Management of the urinothorax required antibiotics and surgical unblocking of the urinary tract. Currently, no test is available to confirm the diagnosis. The ratio of serum creatinine/pleural creatinine could suggest the presence of urinothorax but this parameter needs to be validated by complementary studies. Urinothorax should be suspected in the context of pleural effusion occurring after a recent urologic surgery. Copyright © 2018 SPLF. Published by Elsevier Masson SAS. All rights reserved.
Unblocking brainstorms.

PubMed

Gallupe, R B; Bastianutti, L M; Cooper, W H

1991-02-01

Brainstorming groups have consistently produced fewer ideas than have the equivalent number of individuals working by themselves. These results have been attributed to social loafing, evaluation apprehension, and production blocking in groups. In this study, a new brainstorming technique--electronic brainstorming--that may reduce both production blocking and evaluation apprehension was assessed. Electronic and nonelectronic groups and nominal and interacting groups were compared in a 2 x 2 factorial design. Electronic groups were more productive than nonelectronic groups, but the productivity of nominal and interacting groups did not differ. In contrast, interacting groups felt better about the idea-generation process than did nominal groups. Ways in which electronic brainstorming can reopen a long dormant area of research and application are discussed.
Low temperature magnetic susceptibility behavior of the Neuschwanstein EL6 meteorite and mineral daubreelite (FeCr2S4)

NASA Astrophysics Data System (ADS)

Kohout, T.; Kletetschka, G.; Lehtinen, M.; Pesonen, L. J.; Wasilewski, P. J.

2006-12-01

Neuschwanstein meteorite (enstatite chondrite EL-6) fall occurred on April 6, 2002 close to Neuschwanstein castle in Bavaria, Germany. Total three meteorite bodies were found on the fall site. Two fragments coming from a 1750g body found on July 14, 2002 were obtained to the Division of Geophysics, University of Helsinki. The low temperature magnetic properties were investigated using KLY-3 and KLY-4 kappabridges equipped with low temperature control unit. During the low-temperature susceptibility measurements an unknown kink feature was observed at ~150 K on all measured samples. The closest known magnetic transition is the curie temperature Tc ~170 K of synthetic FeCr2S4 mentioned in Müller et al., 2006. FeCr2S4 is naturally present in enstatite chondrites and iron meteorites in the form of mineral daubreelite and was reported to be present in the Neuschwanstein meteorite in Zipfel and Dreibus, 2003. The extensive study of magnetic susceptibility of Neuschwanstein meteorite and daubreelite extract form Coahuila iron meteorite (hexahedrite, II A) was conducted in order to investigate the low temperature magnetic susceptibility of those materials and its field and frequency dependence. The results indicate Tc of natural daubreelite extract from Coahuila meteorite to be ~160 K what is slightly lower than the Tc of synthetic FeCr2S4 reported in Müller et al., 2006. The magnetic susceptibility of natural daubreelite from Coahuila meteorite and of ~150 K feature in Neuschwanstein meteorite show no field dependence of magnetic susceptibility. Due to the similarity in the low temperature magnetic susceptibility behaviour of Neuschwanstein meteorite and daubreelite extract from Coahuila meteorite we link the Neuschwanstein ~150 K feature to the Tc of daubreelite present in this meteorite. The 10 K difference of the Tc of daubreelite in Neuschwanstein and Coahuila meteorites can be attributed to the presence of impurities or structural deformations in the daubreelite crystals. Daubreelite with its Tc ~160 K may be significant magnetic mineral in cold space environment. However, warming to the terrestrial temperatures results in magnetic unblocking and lost of the magnetic information. The low temperature susceptibility measurements can be used to identify the presence of daubreelite in meteorites. References: C. Muller, V. Zestrea, V. Tsurkan, S. Horn, R. Tidecks and A. Wixforth (2006): SPIN-LATTICE COUPLING IN THE FERRIMAGNETIC SEMICONDUCTOR FeCr2S4 PROBED BY SURFACE ACOUSTIC WAVES. J. Appl. Phys. 99(2), 023906, 2006. J. Zipfel and G. Dreibus (2003): BULK CHEMISTRY OF NEUSCHWANSTEIN (EL6). 66th Annual Meteoritical Society Meeting (2003) Abstract no. A103.
Routing optimization in networks based on traffic gravitational field model

NASA Astrophysics Data System (ADS)

Liu, Longgeng; Luo, Guangchun

2017-04-01

For research on the gravitational field routing mechanism on complex networks, we further analyze the gravitational effect of paths. In this study, we introduce the concept of path confidence degree to evaluate the unblocked reliability of paths that it takes the traffic state of all nodes on the path into account from the overall. On the basis of this, we propose an improved gravitational field routing protocol considering all the nodes’ gravities on the path and the path confidence degree. In order to evaluate the transmission performance of the routing strategy, an order parameter is introduced to measure the network throughput by the critical value of phase transition from a free-flow phase to a jammed phase, and the betweenness centrality is used to evaluate the transmission performance and traffic congestion of the network. Simulation results show that compared with the shortest-path routing strategy and the previous gravitational field routing strategy, the proposed algorithm improves the network throughput considerably and effectively balances the traffic load within the network, and all nodes in the network are utilized high efficiently. As long as γ ≥ α, the transmission performance can reach the maximum and remains unchanged for different α and γ, which ensures that the proposed routing protocol is high efficient and stable.
Further constraints for the Plio-Pleistocene geomagnetic field strength: New results from the Los Tuxtlas volcanic field (Mexico)

NASA Astrophysics Data System (ADS)

Alva-Valdivia, L. M.; Goguitchaichvili, A.; Urrutia-Fucugauchi, J.

2001-09-01

A rock-magnetic, paleomagnetic and paleointensity study was carried out on 13 Plio-Pleistocene volcanic flows from the Los Tuxtlas volcanic field (Trans Mexican Volcanic Belt) in order to obtain some decisive constraints for the geomagnetic field strength during the Plio-Pleistocene time. The age of the volcanic units, which yielded reliable paleointensity estimates, lies between 2.2 and 0.8 Ma according to the available K/Ar radiometric data. Thermomagnetic investigations reveal that remanence is carried in most cases by Ti-poor titanomagnetite, resulting from oxy-exsolution that probably occurred during the initial flow cooling. Unblocking temperature spectra and relatively high coercivity point to 'small' pseudo-single domain magnetic grains for these (titano)magnetites. Single-component, linear demagnetization plots were observed in most cases. Six flows yield reverse polarity magnetization, five flows are normally magnetized, and one flow shows intermediate polarity magnetization. Evidence of a strong lightning-produced magnetization overprint was detected for one site. The mean pole position obtained in this study is Plat = 83.7°, Plong = 178.1°, K = 36, A95 = 8.1°, N =10 and the corresponding mean paleodirection is I = 31.3°, D = 352°, k = 37, a95 = 8.2°, which is not significantly different from the expected direction estimated from the North American apparent polar wander path. Thirty-nine samples were pre-selected for Thellier palaeointensity experiments because of their stable remanent magnetization and relatively weak-within-site dispersion. Only 21 samples, coming from four individual basaltic lava flows, yielded reliable paleointensity estimates with the flow-mean virtual dipole moments (VDM) ranging from 6.4 to 9.1 × 1022 Am2. Combining the coeval Mexican data with the available comparable quality Pliocene paleointensity results yield a mean VDM of 6.4 × 1022 Am2, which is almost 80% of the present geomagnetic axial dipole. Reliable paleointensity results for the last 5~Ma are still scarce and are of dissimilar quality. Additional high-quality absolute intensity determinations are needed to better constraint the geomagnetic field strength during the Plio-Pleistocene time.
Reverse polarity magnetized melt rocks from the Chicxulub impact structure, Yucatan Peninsula, Mexico

NASA Astrophysics Data System (ADS)

Urrutia-Fucugauchi, Jaime; Marin, Luis E.; Sharpton, Virgil L.; Quezada, Juan Manuel

1993-03-01

Further paleomagnetic data for core samples of melt rock recovered in the Petroleos Mexicanos (PEMEX) exploratory wells within the Chicxulub structure, northern Yucatan peninsula, Mexico are reported. A previous report by Sharpton showed that the rocks studied contain high iridium levels and shocked breccia clasts, and an Ar-40/Ar-39 age of 65.2 plus or minus 0.4 Ma. The geomagnetic polarity determined for two samples is reverse (R) and was correlated with chron 29R that includes the K/T boundary. Our present analysis is based on two samples from each of three clasts of the melt rock from PEMEX well Y6-N17 (1295 to 1299 m b.s.l.). This study concentrates on the vectorial nature and stability of the remanence (NRM), the magnetic mineralogy and remanence carriers (i.e., the reliability and origin of the record), and on the implications (correlation with expected paleolatitude and polarity). The relative orientation of the drill core samples with respect to the horizontal is known. Samples were stable under alternating field (AF) and thermal treatments, and after removal of a small component they exhibited single-vectorial behavior. The characteristic remanence inclinations show small dispersion and a mean value (-43 deg) in close agreement with the expected inclination and paleolatitude (derived from the North American apparent polar wander path). Isothermal remenence (IRM) acquisition experiments, Lowrie-Fuller tests, coercivity and unblocking temperature spectra of NRM and saturation IRM, susceptibility and Q-coefficient analyses, and the single-component nature indicate a dominant mineralogy of iron-rich titanomagnetites with single or pseduo-single domain states. The stable characteristic magnetization may be interpreted as a result of shock heating of the rock at the time of formation of the inpact structure and its polarity, age, and paleolatitude are consistent with a time about the K/T boundary.
New Early and Late Carboniferous paleomagnetic results from the Qaidam Block, NW China: Implications for the paleogeography of Central Asia

NASA Astrophysics Data System (ADS)

Cao, Yong; Sun, Zhiming; Li, Haibing; Pei, Junling; Xu, Wei; Pan, Jiawei; Zhang, Lei; Ye, Xiaozhou; Huang, Baochun; Wang, Zongxiu

2017-10-01

There is an ongoing debate regarding the paleogeographic evolution of the Qaidam Block (37.3 °N/96.4 °E) in northwest China during the late Paleozoic. To provide a reliable constraint on the paleogeographic reconstruction and to determine the relationship with the adjacent area, we performed a paleomagnetic investigation of Early and Late Carboniferous sediments from the Qaidam Block. Stepwise thermal demagnetization successfully isolated high unblocking-temperature characteristic directions from the samples. The tilt-corrected mean direction of the Early Carboniferous sediments is Ds/Is = 298.6°/- 46.4° with α95 = 4.7° and N = 15 sites, corresponding to a paleopole at - 3.2 °N, 147.5 °E with A95 = 4.8°. The Late Carboniferous paleomagnetic direction is Ds/Is = 320.1°/- 46.1° with α95 = 5.3° and N = 8 sites, corresponding to a paleopole at - 15.1 °N, 132.2 °E with A95 = 5.4°. A positive fold test for the Early Carboniferous paleomagnetic directions, and consistency with the Kiaman reversed superchron for the Late Carboniferous paleomagnetic directions, indicates the primary origin of the characteristic remanence of the studied section. The new paleomagnetic results suggest that the Qaidam Block was located at about 27 °N and did not undergo significant N-S movement during the Carboniferous. However, the Qaidam Block experienced a counter-clockwise rotation of about 21° during this period. Comparisons of the paleomagnetic results from the major blocks of Central Asia suggest that the Qaidam Block may have experienced a relatively rapid northward movement and collided with the Tarim Block after the Late Permian. Based on the paleomagnetic poles of the Qaidam Block and adjacent blocks, we present a tentative paleogeographic reconstruction for central Asia during the Early and Late Carboniferous.

Reverse polarity magnetized melt rocks from the Chicxulub impact structure, Yucatan Peninsula, Mexico

NASA Technical Reports Server (NTRS)

Urrutia-Fucugauchi, Jaime; Marin, Luis E.; Sharpton, Virgil L.; Quezada, Juan Manuel

1993-01-01

Further paleomagnetic data for core samples of melt rock recovered in the Petroleos Mexicanos (PEMEX) exploratory wells within the Chicxulub structure, northern Yucatan peninsula, Mexico are reported. A previous report by Sharpton showed that the rocks studied contain high iridium levels and shocked breccia clasts, and an Ar-40/Ar-39 age of 65.2 plus or minus 0.4 Ma. The geomagnetic polarity determined for two samples is reverse (R) and was correlated with chron 29R that includes the K/T boundary. Our present analysis is based on two samples from each of three clasts of the melt rock from PEMEX well Y6-N17 (1295 to 1299 m b.s.l.). This study concentrates on the vectorial nature and stability of the remanence (NRM), the magnetic mineralogy and remanence carriers (i.e., the reliability and origin of the record), and on the implications (correlation with expected paleolatitude and polarity). The relative orientation of the drill core samples with respect to the horizontal is known. Samples were stable under alternating field (AF) and thermal treatments, and after removal of a small component they exhibited single-vectorial behavior. The characteristic remanence inclinations show small dispersion and a mean value (-43 deg) in close agreement with the expected inclination and paleolatitude (derived from the North American apparent polar wander path). Isothermal remenence (IRM) acquisition experiments, Lowrie-Fuller tests, coercivity and unblocking temperature spectra of NRM and saturation IRM, susceptibility and Q-coefficient analyses, and the single-component nature indicate a dominant mineralogy of iron-rich titanomagnetites with single or pseduo-single domain states. The stable characteristic magnetization may be interpreted as a result of shock heating of the rock at the time of formation of the inpact structure and its polarity, age, and paleolatitude are consistent with a time about the K/T boundary.
Paleomagnetic and rock magnetic results from Koko Seamount (ODP Leg 197, Site 1206): Implications for hotspot motion

NASA Astrophysics Data System (ADS)

Olton, G.; Cottrell, R. D.; Tarduno, J. A.; Carvallo, C.; Torii, M.; Doubrovine, P. V.

2002-12-01

ODP Leg 197 sought to test whether the Hawaiian hotspot was fixed in the mantle during Late Cretaceous to Early Tertiary times. The principal goal was the recovery of basalt sequences from several of the Emperor seamounts and the main tool to be applied was paleomagnetism. Koko Seamount, near the bend in the Hawaiian-Emperor Seamounts, was the southernmost site drilled during Leg 197. Fifteen basalt units separated by thick volcaniclastic units were recovered in 278 m of penetration. Based on nannofossil stratigraphy of the sediments above basalt, the top of the volcanic section is 43.5-49.7 m.y.-old. Shipboard geochemical analyses (Initial Reports, Leg 197) indicate the lavas include tholeiites, suggesting that the age of the sequence recovered is similar to that of the major phase of shield building. Detailed, stepwise alternating field demagnetization experiments, and subsequent principal component analysis (all conducted aboard the JOIDES Resolution) yielded 14 inclination groups suggesting a mean paleolatitude of 21.7o N, slightly steeper than that the present-day latitude of Hawaii. Shore-based hysteresis measurements of basalt samples indicate single to pseudo-single domain behavior (mean Hc = 170 Oe, Hcr = 309 Oe, Mr/Ms = 0.274), whereas unblocking temperatures range from 200-300 oC and 550-600 oC. These data suggest the presence of high titanium titanomagnetite and magnetite. Shore-based thermal demagnetization inclinations are similar to the shipboard alternating field demagnetization data. The paleomagnetic data from Koko Seamount, together with results from Detroit, Suiko and Nintoku Seamounts form a southward decreasing series of paleolatitudes that appear to track motion of the Hawaiian ``hotspot" in the mantle. Rates of motion based on paleolatitudes of the Emperor Seamounts range from 30-50 mm/yr, similar to that observed for some continental plates.
WE-AB-207A-09: Optimization of the Design of a Moving Blocker for Cone-Beam CT Scatter Correction: Experimental Evaluation

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

Chen, X; Ouyang, L; Jia, X

Purpose: A moving blocker based strategy has shown promising results for scatter correction in cone-beam computed tomography (CBCT). Different geometry designs and moving speeds of the blocker affect its performance in image reconstruction accuracy. The goal of this work is to optimize the geometric design and moving speed of the moving blocker system through experimental evaluations. Methods: An Elekta Synergy XVI system and an anthropomorphic pelvis phantom CIRS 801-P were used for our experiment. A blocker consisting of lead strips was inserted between the x-ray source and the phantom moving back and forth along rotation axis to measure the scattermore » signal. Accoriding to our Monte Carlo simulation results, three blockers were used, which have the same lead strip width 3.2mm and different gap between neighboring lead strips, 3.2, 6.4 and 9.6mm. For each blocker, three moving speeds were evaluated, 10, 20 and 30 pixels per projection (on the detector plane). Scatter signal in the unblocked region was estimated by cubic B-spline based interpolation from the blocked region. CBCT image was reconstructed by a total variation (TV) based algebraic iterative reconstruction (ART) algorithm from the partially blocked projection data. Reconstruction accuracy in each condition is quantified as CT number error of region of interest (ROI) by comparing to a CBCT reconstructed image from analytically simulated unblocked and scatter free projection data. Results: Highest reconstruction accuracy is achieved when the blocker width is 3.2 mm, the gap between neighboring lead strips is 9.6 mm and the moving speed is 20 pixels per projection. RMSE of the CT number of ROIs can be reduced from 436 to 27. Conclusions: Image reconstruction accuracy is greatly affected by the geometry design of the blocker. The moving speed does not have a very strong effect on reconstruction result if it is over 20 pixels per projection.« less
Recovery of NMDA receptor currents from MK-801 blockade is accelerated by Mg2+ and memantine under conditions of agonist exposure

PubMed Central

McKay, Sean; Bengtson, C. Peter; Bading, Hilmar; Wyllie, David J.A.; Hardingham, Giles E.

2013-01-01

MK-801 is a use-dependent NMDA receptor open channel blocker with a very slow off-rate. These properties can be exploited to ‘pre-block’ a population of NMDARs, such as synaptic ones, enabling the selective activation of a different population, such as extrasynaptic NMDARs. However, the usefulness of this approach is dependent on the stability of MK-801 blockade after washout. We have revisited this issue, and confirm that recovery of NMDAR currents from MK-801 blockade is enhanced by channel opening by NMDA, and find that it is further increased when Mg2+ is also present. In the presence of Mg2+, 50% recovery from MK-801 blockade is achieved after 10′ of 100 μM NMDA, or 30′ of 15 μM NMDA exposure. In Mg2+-free medium, NMDA-induced MK-801 dissociation was found to be much slower. Memantine, another PCP-site antagonist, could substitute for Mg2+ in accelerating the unblock of MK-801 in the presence of NMDA. This suggests a model whereby, upon dissociation from its binding site in the pore, MK-801 is able to re-bind in a process antagonized by Mg2+ or another PCP-site antagonist. Finally we show that even when all NMDARs are pre-blocked by MK-801, incubation of neurons with 100 μM NMDA in the presence of Mg2+ for 2.5 h triggers sufficient unblocking to kill >80% of neurons. We conclude that while synaptic MK-801 ‘pre-block’ protocols are useful for pharmacologically assessing synaptic vs. extrasynaptic contributions to NMDAR currents, or studying short-term effects, it is problematic to use this technique to attempt to study the effects of long-term selective extrasynaptic NMDAR activation. This article is part of the Special Issue entitled ‘Glutamate Receptor-Dependent Synaptic Plasticity’. PMID:23402996
SU-F-T-75: Dosimetry Considerations in the Use of Hanging-Eye Block for Lesions of the Conjunctiva

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

Grelewicz, Z; Lee, B; Cutright, D

Purpose: Superficial lesions in the conjunctiva are frequently treated with en face electrons, using a hanging block to spare dose to the lens of the eye. Dose to the tumor and lens depend on the design and setup of the block and supporting apparatus. We performed in phantom measurements in order to characterize the dose sparing effects of the block as well as the under-dosing effect under the supporting apparatus for 6 MeV treatment. Methods: The commercial hanging block studied uses a 1.2 cm diameter tungsten cylinder supported by a 3 mm diameter acrylic rod. Point dose measurements under themore » hanging block, under an unblocked part of the field, and under the acrylic rod were performed using MOSFET detectors. In addition, EBT3 film was used for both PDD and profile measurements at a depth in phantom of 3 mm for both 105 and 103 cm SSD. Results: MOSFET measurements reported a dose reduction of 95% under the tungsten block when using an SSD of 103 cm, and 86% when using an SSD of 105 cm at a depth in phantom of 3 mm. Film measurements showed that the area under the acrylic rod may be under-dosed by as much as 30% when using 103 SSD. MOSFET measurements confirmed that when using an SSD of 103 cm, the area under the acrylic rod is under-dosed by up to 30% at 3mm depth, compared to the unblocked part of the field. Conclusion: The effectiveness of the commercial hanging block apparatus depends on setup, with 95% lens sparing possible with an SSD of 103 cm. This short SSD is necessary for sharp penumbra. At this SSD, substantial under-dosing under the acrylic support rod is possible. This must be mitigated with either feathering, or using an alternative method of support for the tungsten block.« less
Recovery of NMDA receptor currents from MK-801 blockade is accelerated by Mg2+ and memantine under conditions of agonist exposure.

PubMed

McKay, Sean; Bengtson, C Peter; Bading, Hilmar; Wyllie, David J A; Hardingham, Giles E

2013-11-01

MK-801 is a use-dependent NMDA receptor open channel blocker with a very slow off-rate. These properties can be exploited to 'pre-block' a population of NMDARs, such as synaptic ones, enabling the selective activation of a different population, such as extrasynaptic NMDARs. However, the usefulness of this approach is dependent on the stability of MK-801 blockade after washout. We have revisited this issue, and confirm that recovery of NMDAR currents from MK-801 blockade is enhanced by channel opening by NMDA, and find that it is further increased when Mg(2+) is also present. In the presence of Mg(2+), 50% recovery from MK-801 blockade is achieved after 10' of 100 μM NMDA, or 30' of 15 μM NMDA exposure. In Mg(2+)-free medium, NMDA-induced MK-801 dissociation was found to be much slower. Memantine, another PCP-site antagonist, could substitute for Mg(2+) in accelerating the unblock of MK-801 in the presence of NMDA. This suggests a model whereby, upon dissociation from its binding site in the pore, MK-801 is able to re-bind in a process antagonized by Mg(2+) or another PCP-site antagonist. Finally we show that even when all NMDARs are pre-blocked by MK-801, incubation of neurons with 100 μM NMDA in the presence of Mg(2+) for 2.5 h triggers sufficient unblocking to kill >80% of neurons. We conclude that while synaptic MK-801 'pre-block' protocols are useful for pharmacologically assessing synaptic vs. extrasynaptic contributions to NMDAR currents, or studying short-term effects, it is problematic to use this technique to attempt to study the effects of long-term selective extrasynaptic NMDAR activation. This article is part of the Special Issue entitled 'Glutamate Receptor-Dependent Synaptic Plasticity'. Copyright © 2013 Elsevier Ltd. All rights reserved.
Avoiding the Pitfalls of Anisotropy in Paleomagnetic Correlation of Snake River Plain Ignimbrites

NASA Astrophysics Data System (ADS)

Finn, D. R.; Coe, R. S.; Kelly, H.; Murphy, J.; Reichow, M. K.; Knott, T.; Branney, M.

2013-12-01

Migration of the Yellowstone hotspot center tracks northeast along the central Snake River Plain (cSRP), leaving a succession of calderas, bimodal rhyolitic and basaltic volcanism, and crustal deformation. Large-scale explosive volcanism common to this province between 12.5-8 Ma is characterized by unusually high-temperature, intensely welded, rheomorphic rhyolitic ignimbrites, typical of what is now known as ';Snake River (SR)-type volcanism'. Individual eruption volumes likely exceed 450 km3 but are poorly known due to the difficulty of correlating units between widely spaced (50-200 km) exposures along the north and south of the plain. Radiometric dating does not have the resolution to identify the eruptive units. Our goal is to use a combination of paleomagnetic, petrographic, chemical and field characterization to establish robust correlations and better constrain eruption volumes and frequencies. Paleomagnetic correlation using the stable remanence, which is the focus of this presentation, has the advantage of very high temporal resolution of the order of centuries. This is due to the geologically rapid rate of geomagnetic secular variation and high accuracy to which extrusive rocks may record the instantaneous direction of the magnetic field. We have collected more than 1200 paleomagnetic samples from over 90 sites to help build a regional stratigraphy between the dozens of known ignimbrite units in the cSRP. During this process, however, we have found that the use of paleomagnetism is complicated by the large variation in the paleomagnetic direction that sometimes exists both within and between sub-lithologies of the same flow. Individual SR-type ignimbrite cooling-units have an upper and lower glassy margin (vitrophyre) enclosing a lithoidal (microcrystalline) zone. These vitrophyre lithologies often have a shallow paleomagnetic direction compared to the lithoidal lithologies. Here we present preliminary results from a detailed paleomagnetic and rock magnetic study of one cooling unit and its thermal contact zone to better understand the source of discrepant directions. We found a relationship between anisotropy of thermal remanent magnetization (ATRM), coercivity, natural remanent magnetization intensity, and deflection of remanence direction. A strong lineation in the ATRM anisotropy suggests contemporaneous rheomorphic shear strain of the welding fabric during early stages of emplacement plays a key role in generating magnetic anisotropy. The low anisotropy of the lithoidal zone and its correlation with the magnetic direction of the underlying baked soil implies that crystallization somehow helps anneal this anisotropy prior to cooling below the unblocking temperature of the constituent magnetic minerals. We hypothesize that the glassy margins retain an anisotropic fabric related to emplacement which affects their ability to accurately record the magnetic field during cooling. The anisotropic fabric in the lithoidal zone is overprinted by continued grain growth and/or alteration and, therefore, more accurately records the paleomagnetic field direction.
Compressive Coded-Aperture Multimodal Imaging Systems

NASA Astrophysics Data System (ADS)

Rueda-Chacon, Hoover F.

Multimodal imaging refers to the framework of capturing images that span different physical domains such as space, spectrum, depth, time, polarization, and others. For instance, spectral images are modeled as 3D cubes with two spatial and one spectral coordinate. Three-dimensional cubes spanning just the space domain, are referred as depth volumes. Imaging cubes varying in time, spectra or depth, are referred as 4D-images. Nature itself spans different physical domains, thus imaging our real world demands capturing information in at least 6 different domains simultaneously, giving turn to 3D-spatial+spectral+polarized dynamic sequences. Conventional imaging devices, however, can capture dynamic sequences with up-to 3 spectral channels, in real-time, by the use of color sensors. Capturing multiple spectral channels require scanning methodologies, which demand long time. In general, to-date multimodal imaging requires a sequence of different imaging sensors, placed in tandem, to simultaneously capture the different physical properties of a scene. Then, different fusion techniques are employed to mix all the individual information into a single image. Therefore, new ways to efficiently capture more than 3 spectral channels of 3D time-varying spatial information, in a single or few sensors, are of high interest. Compressive spectral imaging (CSI) is an imaging framework that seeks to optimally capture spectral imagery (tens of spectral channels of 2D spatial information), using fewer measurements than that required by traditional sensing procedures which follows the Shannon-Nyquist sampling. Instead of capturing direct one-to-one representations of natural scenes, CSI systems acquire linear random projections of the scene and then solve an optimization algorithm to estimate the 3D spatio-spectral data cube by exploiting the theory of compressive sensing (CS). To date, the coding procedure in CSI has been realized through the use of ``block-unblock" coded apertures, commonly implemented as chrome-on-quartz photomasks. These apertures block or permit to pass the entire spectrum from the scene at given spatial locations, thus modulating the spatial characteristics of the scene. In the first part, this thesis aims to expand the framework of CSI by replacing the traditional block-unblock coded apertures by patterned optical filter arrays, referred as ``color" coded apertures. These apertures are formed by tiny pixelated optical filters, which in turn, allow the input image to be modulated not only spatially but spectrally as well, entailing more powerful coding strategies. The proposed colored coded apertures are either synthesized through linear combinations of low-pass, high-pass and band-pass filters, paired with binary pattern ensembles realized by a digital-micromirror-device (DMD), or experimentally realized through thin-film color-patterned filter arrays. The optical forward model of the proposed CSI architectures will be presented along with the design and proof-of-concept implementations, which achieve noticeable improvements in the quality of the reconstructions compared with conventional block-unblock coded aperture-based CSI architectures. On another front, due to the rich information contained in the infrared spectrum as well as the depth domain, this thesis aims to explore multimodal imaging by extending the range sensitivity of current CSI systems to a dual-band visible+near-infrared spectral domain, and also, it proposes, for the first time, a new imaging device that captures simultaneously 4D data cubes (2D spatial+1D spectral+depth imaging) with as few as a single snapshot. Due to the snapshot advantage of this camera, video sequences are possible, thus enabling the joint capture of 5D imagery. It aims to create super-human sensing that will enable the perception of our world in new and exciting ways. With this, we intend to advance in the state of the art in compressive sensing systems to extract depth while accurately capturing spatial and spectral material properties. The applications of such a sensor are self-evident in fields such as computer/robotic vision because they would allow an artificial intelligence to make informed decisions about not only the location of objects within a scene but also their material properties.
Remagnetization of lava flows spanning the last geomagnetic reversal

NASA Astrophysics Data System (ADS)

Vella, Jérôme; Carlut, Julie; Valet, Jean-Pierre; Goff, Maxime Le; Soler, Vicente; Lopes, Fernando

2017-08-01

Large directional changes of remanent magnetization within lava flows that cooled during geomagnetic reversals have been reported in several studies. A geomagnetic scenario implies extremely rapid geomagnetic changes of several degrees per day, thus difficult to reconcile with the rate of the earth's core liquid motions. So far, no complete rock magnetic model provides a clear explanation. We revisited lava flows sandwiched between an underlying reverse and an overlying normal polarity flow marking the last reversal in three distinct volcanic sequences of the La Palma Island (Canary archipelago, Spain) that are characterized by a gradual evolution of the direction of their remanent magnetization from bottom to top. Cleaning efficiency of thermal demagnetization was not improved by very rapid heating and cooling rates as well as by continuous demagnetization using a Triaxe magnetometer. We did not observe partial self-reversals and minor changes in magnetic grain sizes are not related to the within-flow directional changes. Microscopic observations indicate poor exsolution, which suggests post-cooling thermochemical remagnetization processes. This scenario is strongly reinforced by laboratory experiments that show large resistance to thermal demagnetization when thermoremanence was acquired over a long time period. We speculate that in the present situation exsolution was reactivated during in field reheating and yielded formation of new magnetite, yet magnetic domain state rearrangements could also play a role. Initial reheating when the overlying flow took place, albeit moderate (less than 200-300 °C), was enough to produce overlying components with significantly higher unblocking temperatures.
Paleomagnetism of Hadean and Archean Detrital Zircons from the Jack Hills, Western Australia

NASA Astrophysics Data System (ADS)

Weiss, B. P.; Lima, E. A.; Alexander, E.; Bell, E. A.; Boehnke, P.; Wielicki, M. M.; Harrison, M.; Fu, R. R.; Kehayias, P.; Glenn, D. R.; Walsworth, R. L.; Araujo, J. F. D.; Einsle, J. F.; Harrison, R.; Trail, D.; Watson, E. B.

2016-12-01

Determining the history of Earth's dynamo prior to the oldest known well-preserved rock record is one of the ultimate challenges in the field of paleomagnetism. The dynamo's early history has major implications for the evolution of the core, the initiation of plate tectonics, the physics of magnetic field generation, and the habitability of the early Earth. The only known minerals that might retain paleomagnetic records from well before 3.5 billion years ago (Ga) are detrital zircon crystals found in sedimentary rocks in Western Australia. Ranging up to 4.38 Ga in age, they are the oldest known terrestrial minerals. Tarduno et al. (2015) argued that detrital zircons contain records of an active dynamo dating back to 4.2 Ga. However, it has not been demonstrated that the zircons have escaped remagnetization during the intervening time since their formation (Weiss et al. 2016). Therefore, the age of magnetization in the Jack Hills zircons and the existence of a dynamo prior to 3.5 Ga have yet to be established. To address this issue, we have been studying the magnetism and thermal and aqueous alteration histories of single Archean and Hadean Jack Hills zircon crystals. Peak unblocking temperatures combined with electron backscatter diffraction indicate that the zircons contain inclusions of magnetite and hematite. Electron microscopy, X-ray tomography, and quantum diamond magnetometry indicate that much of the iron oxides in the zircons are associated with cracks and are therefore likely secondary. However, our newly developed Li-in-zircon geospeedometry technique shows for the first time that a small fraction of Hadean zircons retain sharp gradients in Li concentration (see figure), indicating they likely have never heated above the magnetite Curie temperature since their formation at >4 Ga. We describe thermal demagnetization and Thellier-Thellier paleointensity studies of these zircons and implications for the existence of a Hadean dynamo.
The Role of Authigenic (pigment) Hematite in Controlling the Remanence, Rock Magnetic, and Magnetic Fabric Properties of Red Beds--If You Have Seen One Red Bed, You Certainly Have Not Seen Them All!

NASA Astrophysics Data System (ADS)

Geissman, J. W.

2014-12-01

Discussion continues on the relative role of authigenic (pigment) fine-grained hematite, relative to detrital, considerably coarser specular hematite (specularite) as a carrier of geologically meaningful remanence, as a determinant of rock magnetic properties, and as a contributor to magnetic fabrics in red beds. For one, many workers commonly assume that the laboratory unblocking temperature spectra (Tlub) of a red bed dominated by authigenic pigment does not reach the maximum Tlub as approximated by the Neel temperature (~948 K) because of the ultra fine grain size of the pigment. This issue was discussed as recently as the IRM Santa Fe meeting in late June, 2014. Many laboratories routinely utilize chemical demagnetization in concert with progressive thermal demagnetization to attempt to assess the relative role of pigment vs. detrital hematite. However, the utility of chemical demagnetization has been long challenged. In studying the anisotropy of magnetic susceptibility and remanence in red beds, recent work has considered separating the contributions of both types of hematite to the fabric signal. Three different red bed "types" (siltstones of the Triassic Chugwater Group, Gros Ventre Range, Wyoming; mudrocks of lowermost Triassic Quartermaster Formation, west Texas; and siltstones to medium sandstones of Upper Cretaceous age, northwest Vietnam) are used to evaluate the effects of varying contributions by pigment hematite to remanence, rock magnetic, and magnetic fabric properties. All rocks are well-characterized petrographically, so that the modal abundance of detrital oxides is known. The Chugwater siltstones are notable because of a relatively low Tlub spectra (below about 620o C), with no evidence of a low coercivity cubic phase. Rock magnetic and magnetic fabric properties are monitored as a function of progressive chemical demagnetization to further elucidate the role of hematite pigment in rocks that have contributed much to the paleomagnetic record of Earth.
Archeointensity study on baked clay samples taken from the reconstructed ancient kiln: implication for validity of the Tsunakawa-Shaw paleointensity method

NASA Astrophysics Data System (ADS)

Yamamoto, Yuhji; Torii, Masayuki; Natsuhara, Nobuyoshi

2015-05-01

In 1972, a reconstruction experiment of a kiln had been done to reproduce an excavated kiln of the seventh century in Japan. Baked clay samples were taken from the floor surface and -20 cm level, and they have been stored after determinations of the paleomagnetic directions by partial alternating field demagnetizations. We recently applied the Tsunakawa-Shaw method to the samples to assess how reliable archeointensity results are obtained from the samples. A suite of the rock magnetic experiments and the scanning electron microscope observations elucidate that dominant magnetic carriers of the floor surface samples are Ti-poor titanomagnetite grains in approximately 10 nm size with single-domain and/or super-paramagnetic states, whereas contributions of multi-domain grains seem to be relatively large for the -20-cm level samples. From the floor surface samples, six out of the eight successful results were obtained and they give an average of 47.3 μT with a standard deviation of 2.2 μT. This is fairly consistent with the in situ geomagnetic field of 46.4 Î¼T at the time of the reconstruction. They are obtained with a built-in anisotropy correction using anhysteretic remanent magnetization and without any cooling rate corrections. In contrast, only one out of four was successful from the -20-cm level samples. It yields an archeointensity of 31.6 μT, which is inconsistent with the in situ geomagnetic field. Considering from the in situ temperature record during the firing of the kiln and the unblocking temperature spectra of the samples, the floor surface samples acquired full thermoremanent magnetizations (TRMs) as their natural remanent magnetizations whereas the -20-cm level samples only acquired partial TRMs, and these differences probably cause the difference in the archeointensity results between the two sample groups. For archeointensity researches, baked clay samples from a kiln floor are considered to be ideal materials.
Magnetism of Tissint Martian meteorite

NASA Astrophysics Data System (ADS)

Rochette, P.; Gattacceca, J.; Hewins, R.; Lagroix, F.; Uehara, M.; Cournede, C.; Chennaoui Aoudjehane, H.; Zanda, B.; Bernstein Scorzelli, R.

2012-12-01

The Tissint meteorite, an olivine-phyric shergottite that fell in July 2010 in Morocco, is only the fifth Martian meteorite fall. It offers the opportunity to study the magnetic mineralogy and the paleomagnetic signal of a pristine sample from Mars. We have performed such a magnetic study of 35 samples from the Tissint meteorite, with mass ranging from 30 mg to 30 g. We have measured a variety of magnetic properties (natural remanence an its behaviour upon thermal and alternating field demagnetization, hysteresis parameters at room and low temperatures, anisotropy of magnetic susceptibility, unblocking temperature spectrum etc). Less conventional experiments include magneto-optical imaging (coupled with electron microprobe analyses) and Mössbauer spectroscopy. The magnetic mineralogy of Tissint consists of 0.6 wt.% of metastable hexagonal ferrimagnetic pyrrhotite, and 0.1 wt.% of low Ti titanomagnetite formed by oxidation/exsolution of ulvöspinel grains. The magnetic mineralogy of Tissint consists of 0.6 wt.% of metastable hexagonal ferrimagnetic pyrrhotite, and 0.1 wt.% of low Ti titanomagnetite formed by oxidation/exsolution of ulvöspinel grains, for those minerals that are ferromagnetic at temperatures encountered at the Martian surface. Chromite (with a Curie temperature of 70K) is present with an abundance of 0.5 wt.%. Overall, these properties are in broad agreement with the other pyrrhotite-bearing basaltic shergottites, but the presence of magnetite exsolution in ulvöspinel has rarely been documented in other shergottites. We show for the first time that the magnetic fabric is homogeneous in direction in the meteorite, and may well be a proxy to the Martian paleohorizontal at the time of crystallization. The natural remanent magnetization of Tissint was acquired during post-impact cooling in a stable ambient field of about 1 μT of crustal origin. It is noteworthy that the oxides in Tissint are not magnetized, indicating that they were formed at low temperatures below ~300° (i.e. after the major shock event that led to partial melting), and are deformed indicating successive shock events. Such a lithology, if magnetized in a Martian dynamo magnetic field of 50 μT, would carry a remanent magnetization of ~ 3 A/m. This is way below the 10 to 15 A/m that are necessary over a crustal thickness of about 40 km to account for the observed magnetic anomalies at the Martian surface, which confirms that shergottite-like rocks cannot account for these anomalies.
Monte Carlo simulation of HERD calorimeter

NASA Astrophysics Data System (ADS)

Xu, M.; Chen, G. M.; Dong, Y. W.; Lu, J. G.; Quan, Z.; Wang, L.; Wang, Z. G.; Wu, B. B.; Zhang, S. N.

2014-07-01

The High Energy cosmic-Radiation Detection (HERD) facility onboard China's Space Station is planned for operation starting around 2020 for about 10 years. It is designed as a next generation space facility focused on indirect dark matter search, precise cosmic ray spectrum and composition measurements up to the knee energy, and high energy gamma-ray monitoring and survey. The calorimeter plays an essential role in the main scientific objectives of HERD. A 3-D cubic calorimeter filled with high granularity crystals as active material is a very promising choice for the calorimeter. HERD is mainly composed of a 3-D calorimeter (CALO) surrounded by silicon trackers (TK) from all five sides except the bottom. CALO is made of 9261 cubes of LYSO crystals, corresponding to about 55 radiation lengths and 3 nuclear interaction lengths, respectively. Here the simulation results of the performance of CALO with GEANT4 and FLUKA are presented: 1) the total absorption CALO and its absorption depth for precise energy measurements (energy resolution: 1% for electrons and gammarays beyond 100 GeV, 20% for protons from 100 GeV to 1 PeV); 2) its granularity for particle identification (electron/proton separation power better than 10-5); 3) the homogenous geometry for detecting particles arriving from every unblocked direction for large effective geometrical factor (<3 m2sr for electron and diffuse gammarays, >2 m2sr for cosmic ray nuclei); 4) expected observational results such as gamma-ray line spectrum from dark matter annihilation and spectrum measurement of various cosmic ray chemical components.
Common agents used to unblock blood clots within tympanostomy tubes: an ex vivo study and review of literature.

PubMed

Burke, Emily L; Walvekar, Rohan R; Lin, James; Hagan, Joseph; Kluka, Evelyn A

2009-12-01

To determine the efficacy of common solutions used to dissolve blood clots blocking tympanostomy tubes (TTs) of differing lengths and diameters. An ex vivo experimental study. Ear models were built by the study investigator. Tympanostomy tubes were inserted into the models and blocked with blood clots. Test solutions were applied to the blood clots, and time for clearance was recorded via microscopic visual confirmation. Richards T-tube had higher odds of unclogging than collar button tubes (odds ratio: 2.37, 95% confidence intervals 1.02-5.54, p=0.042). Vinegar and 3% hydrogen peroxide were most effective for Richards T-tubes and collar button tubes, respectively. Common solutions (vinegar and hydrogen peroxide) were more effective than antibiotic drops in clearing blood clot blocking TTs.
The proteolytic processing site of the precursor of lysyl oxidase.

PubMed Central

Cronshaw, A D; Fothergill-Gilmore, L A; Hulmes, D J

1995-01-01

The precise cleavage site of the N-terminal propeptide region of the precursor of lysyl oxidase has not yet been established, due to N-terminal blocking of the mature protein. Using a combination of peptide fragmentation, amino acid sequencing, time-of-flight m.s. and partial chemical unblocking procedures, it is shown that the mature form of lysyl oxidase begins at residue Asp-169 of the precursor protein (numbered according to the human sequence). The cleavage site is 28 residues to the C-terminal side of the site previously suggested on the basis of apparant molecular mass by SDS/PAGE, with the consequence that the two putative, N-linked glycosylation sites and the position of the Arg/Gln sequence polymorphism are now all in the precursor region. PMID:7864821
Amino terminal sequence of heavy and light chains from ratfish immunoglobulin.

PubMed

De Ioannes, A E; Aguila, H L

1989-01-01

The ratfish, Callorhinchus callorhinchus, a representative of the Holocephali, has a natural serum hemagglutinin (Mr 960,000), composed of heavy (Mr 71,000), light (Mr 22,500), and J (Mr 16,000) chains. To approach the mechanisms that generate diversity at this level of evolution, the amino terminal sequence of the heavy and light chains was determined by automated microsequencing. The chains are unblocked and have modest internal sequence heterogeneity. The heavy chains show sequence similarity with the terminal region of the heavy chain from the horned shark, Heterodontus francisci, and other species. In contrast to the heavy chain, the ratfish light chains display low sequence similarity with their shark kappa counterparts. However, their similarity with the variable region of the chicken lambda light chains is about 75%.
Retrograde exchange of heavily encrusted ureteric stents via the ileal conduit: a technical report.

PubMed

Tapping, Charles Ross; Boardman, Phil

2014-02-01

We describe two cases of retrograde ureteric stent exchange of heavily encrusted ureteric stents (JJ) via tortuous ileal conduits. The blocked ureteric stents were snared from inside the conduit so they could be accessed and a wire inserted. The lumens of the stents were unblocked with a wire but the stents could not be withdrawn due to heavy encrustation of the ureteric stent in the renal pelvis. A stiff wire was inserted to provide support and a 9 French peel away sheath was used to remove the encrustations allowing the stents to be withdrawn and exchanged. This is a safe and successful technique allowing ureteric stents to be removed when heavily encrusted. © 2013 The Royal Australian and New Zealand College of Radiologists.
SU-E-J-10: A Moving-Blocker-Based Strategy for Simultaneous Megavoltage and Kilovoltage Scatter Correction in Cone-Beam Computed Tomography Image Acquired During Volumetric Modulated Arc Therapy

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

Ouyang, L; Lee, H; Wang, J

2014-06-01

Purpose: To evaluate a moving-blocker-based approach in estimating and correcting megavoltage (MV) and kilovoltage (kV) scatter contamination in kV cone-beam computed tomography (CBCT) acquired during volumetric modulated arc therapy (VMAT). Methods: XML code was generated to enable concurrent CBCT acquisition and VMAT delivery in Varian TrueBeam developer mode. A physical attenuator (i.e., “blocker”) consisting of equal spaced lead strips (3.2mm strip width and 3.2mm gap in between) was mounted between the x-ray source and patient at a source to blocker distance of 232mm. The blocker was simulated to be moving back and forth along the gantry rotation axis during themore » CBCT acquisition. Both MV and kV scatter signal were estimated simultaneously from the blocked regions of the imaging panel, and interpolated into the un-blocked regions. Scatter corrected CBCT was then reconstructed from un-blocked projections after scatter subtraction using an iterative image reconstruction algorithm based on constraint optimization. Experimental studies were performed on a Catphan 600 phantom and an anthropomorphic pelvis phantom to demonstrate the feasibility of using moving blocker for MV-kV scatter correction. Results: MV scatter greatly degrades the CBCT image quality by increasing the CT number inaccuracy and decreasing the image contrast, in addition to the shading artifacts caused by kV scatter. The artifacts were substantially reduced in the moving blocker corrected CBCT images in both Catphan and pelvis phantoms. Quantitatively, CT number error in selected regions of interest reduced from 377 in the kV-MV contaminated CBCT image to 38 for the Catphan phantom. Conclusions: The moving-blockerbased strategy can successfully correct MV and kV scatter simultaneously in CBCT projection data acquired with concurrent VMAT delivery. This work was supported in part by a grant from the Cancer Prevention and Research Institute of Texas (RP130109) and a grant from the American Cancer Society (RSG-13-326-01-CCE)« less
The tetravalent organic cation spermine causes the gating of the IRK1 channel expressed in murine fibroblast cells.

PubMed Central

Ishihara, K; Hiraoka, M; Ochi, R

1996-01-01

1. The activation kinetics of the IRK1 channel stably expressed in L cells (a murine fibroblast cell line) were studied under the whole-cell voltage clamp. Without polyamines or Mg2+ in the pipettes, inward currents showed an exponential activation on hyperpolarization. The steep inward rectification of the currents around the reversal potential (Erev) could be described by the open-close transition of the channel with first-order kinetics. 2. When the tetravalent organic cation spermine (Spm) was added in the pipettes, the activation kinetics changed; this was explicable by the increase in the closing rate constant. The activation of the currents observed without Spm or Mg2+ in the pipettes was ascribed to the unblocking of the 'endogenous-Spm block'. 3. In the presence of the divalent cation putrescine (Put) or of Mg2+ in the pipettes, a different non-conductive state suppressed the outward currents on depolarization; the channels instantaneously changed to the open state on repolarization. As the depolarization was prolonged, this non-conductive state was replaced by the non-conductive state that shows an exponential activation on repolarization. This phenomenon was attributed to the redistribution of the channels from the Put- or Mg(2+)-blocked state to the 'endogenous Spm-blocked state' during depolarization. 4. In the presence of the trivalent cation spermidine (Spd) in the pipettes, two different non-conductive states occurred, showing a faster and a slower activation on repolarization. The rectification around Erev was mainly due to the non-conductive state showing a faster activation, which appeared to be the Spd-blocked state. During depolarization, redistribution of the channels to the 'endogenous Spm-blocked state' also occurred. 5. In the presence of Spd, Put or Mg2+ in the pipettes, the voltage dependence of the activation time constant reflecting the unblocking of the 'endogenous Spm' was shifted in the hyperpolarizing direction. 6. Our results suggest that the 'intrinsic gating' that shows the time-dependent activation on repolarization, and that is responsible for the inward rectification around Erev, reflects the blocking kinetics of the tetravalent Spm. PMID:8866861

Effect of gravity on liquid plug transport through an airway bifurcation model.

PubMed

Zheng, Y; Anderson, J C; Suresh, V; Grotberg, J B

2005-10-01

Many medical therapies require liquid plugs to be instilled into and delivered throughout the pulmonary airways. Improving these treatments requires a better understanding of how liquid distributes throughout these airways. In this study, gravitational and surface mechanisms determining the distribution of instilled liquids are examined experimentally using a bench-top model of a symmetrically bifurcating airway. A liquid plug was instilled into the parent tube and driven through the bifurcation by a syringe pump. The effect of gravity was adjusted by changing the roll angle (phi) and pitch angle (gamma) of the bifurcation (phi = gamma =0 deg was isogravitational). Phi determines the relative gravitational orientation of the two daughter tubes: when phi not equal to 0 deg, one daughter tube was lower (gravitationally favored) compared to the other. Gamma determines the component of gravity acting along the axial direction of the parent tube: when gamma not equal to 0 deg, a nonzero component of gravity acts along the axial direction of the parent tube. A splitting ratio Rs, is defined as the ratio of the liquid volume in the upper daughter to the lower just after plug splitting. We measured the splitting ratio, Rs, as a function of: the parent-tube capillary number (Cap); the Bond number (Bo); phi; gamma; and the presence of pre-existing plugs initially blocking either daughter tube. A critical capillary number (Cac) was found to exist below which no liquid entered the upper daughter (Rs = 0), and above which Rs increased and leveled off with Cap. Cac increased while Rs decreased with increasing phi, gamma, and Bo for blocked and unblocked cases at a given Cap > Ca,. Compared to the nonblockage cases, Rs decreased (increased) at a given Cap while Cac increased (decreased) with an upper (lower) liquid blockage. More liquid entered the unblocked daughter with a blockage in one daughter tube, and this effect was larger with larger gravity effect. A simple theoretical model that predicts Rs and Cac is in qualitative agreement with the experiments over a wide range of parameters.
Virtual directions in paleomagnetism: A global and rapid approach to evaluate the NRM components.

NASA Astrophysics Data System (ADS)

Ramón, Maria J.; Pueyo, Emilio L.; Oliva-Urcia, Belén; Larrasoaña, Juan C.

2017-02-01

We introduce a method and software to process demagnetization data for a rapid and integrative estimation of characteristic remanent magnetization (ChRM) components. The virtual directions (VIDI) of a paleomagnetic site are “all” possible directions that can be calculated from a given demagnetization routine of “n” steps (being m the number of specimens in the site). If the ChRM can be defined for a site, it will be represented in the VIDI set. Directions can be calculated for successive steps using principal component analysis, both anchored to the origin (resultant virtual directions RVD; m * (n2+n)/2) and not anchored (difference virtual directions DVD; m * (n2-n)/2). The number of directions per specimen (n2) is very large and will enhance all ChRM components with noisy regions where two components were fitted together (mixing their unblocking intervals). In the same way, resultant and difference virtual circles (RVC, DVC) are calculated. Virtual directions and circles are a global and objective approach to unravel different natural remanent magnetization (NRM) components for a paleomagnetic site without any assumption. To better constrain the stable components, some filters can be applied, such as establishing an upper boundary to the MAD, removing samples with anomalous intensities, or stating a minimum number of demagnetization steps (objective filters) or selecting a given unblocking interval (subjective but based on the expertise). On the other hand, the VPD program also allows the application of standard approaches (classic PCA fitting of directions a circles) and other ancillary methods (stacking routine, linearity spectrum analysis) giving an objective, global and robust idea of the demagnetization structure with minimal assumptions. Application of the VIDI method to natural cases (outcrops in the Pyrenees and u-channel data from a Roman dam infill in northern Spain) and their comparison to other approaches (classic end-point, demagnetization circle analysis, stacking routine and linearity spectrum analysis) allows validation of this technique. The VIDI is a global approach and it is especially useful for large data sets and rapid estimation of the NRM components.
A computational model of prefrontal control in free recall: strategic memory use in the California Verbal Learning Task.

PubMed

Becker, Suzanna; Lim, Jean

2003-08-15

Several decades of research into the function of the frontal lobes in brain-damaged patients, and more recently in intact individuals using function brain imaging, has delineated the complex executive functions of the frontal cortex. And yet, the mechanisms by which the brain achieves these functions remain poorly understood. Here, we present a computational model of the role of the prefrontal cortex (PFC) in controlled memory use that may help to shed light on the mechanisms underlying one aspect of frontal control: the development and deployment of recall strategies. The model accounts for interactions between the PFC and medial temporal lobe in strategic memory use. The PFC self-organizes its own mnemonic codes using internally derived performance measures. These mnemonic codes serve as retrieval cues by biasing retrieval in the medial temporal lobe memory system. We present data from three simulation experiments that demonstrate strategic encoding and retrieval in the free recall of categorized lists of words. Experiment 1 compares the performance of the model with two control networks to evaluate the contribution of various components of the model. Experiment 2 compares the performance of normal and frontally lesioned models to data from several studies using frontally intact and frontally lesioned individuals, as well as normal, healthy individuals under conditions of divided attention. Experiment 3 compares the model's performance on the recall of blocked and unblocked categorized lists of words to data from Stuss et al. (1994) for individuals with control and frontal lobe lesions. Overall, our model captures a number of aspects of human performance on free recall tasks: an increase in total words recalled and in semantic clustering scores across trials, superiority on blocked lists of related items compared to unblocked lists of related items, and similar patterns of performance across trials in the normal and frontally lesioned models, with poorer overall performance of the lesioned models on all measures. The model also has a number of shortcomings, in light of which we suggest extensions to the model that would enable more sophisticated forms of strategic control.
When did the lunar core dynamo cease?

NASA Astrophysics Data System (ADS)

Tikoo, S. M.; Weiss, B. P.; Shuster, D. L.; Fuller, M.

2013-12-01

Remanent magnetization in the lunar crust and in returned Apollo samples has long suggested that the Moon formed a metallic core and an ancient dynamo magnetic field. Recent paleomagnetic investigations of lunar samples demonstrate that the Moon had a core dynamo which produced ~30-110 μT surface fields between at least 4.2 and 3.56 billion years ago (Ga). Tikoo et al. (1) recently found that the field declined to below several μT by 3.19 Ga. However, given that even values of a few μT are at the upper end of the intensities predicted by dynamo theory for this late in lunar history, it remains uncertain when the lunar dynamo actually ceased completely. Determining this requires a young lunar rock with extraordinarily high magnetic recording fidelity. With this goal, we are conducting a new analysis of young regolith breccia 15498. Although the breccia's age is currently uncertain, the presence of Apollo 15-type mare basalt clasts provides an upper limit constraint of ~3.3 Ga, while trapped Ar data suggest a lithification age of ~1.3 Ga. In stark contrast to the multidomain character of virtually all lunar crystalline rocks, the magnetic carriers in 15498 are on average pseudo-single domain to superparamagnetic, indicating that the sample should provide high-fidelity paleointensity records. A previous alternating field (AF) and thermal demagnetization study of 15498 by Gose et al. (2) observed that the sample carries stable remanent magnetization which persists to unblocking temperatures of at least 650°C. Using a modified Thellier technique, they reported a paleointensity of 2 μT. Although this value may have been influenced by spurious remanence acquired during pretreatment with AF demagnetization, our results confirm the presence of an extremely stable (blocked to coercivities >290 mT) magnetization in the glassy matrix. We also found that this magnetization is largely unidirectional across mutually oriented subsamples. The cooling timescale of this rock (~1 hour) likely precludes impact fields as a source of thermoremanent magnetization. Our paleointensity experiments and Ar/Ar thermochronometry, currently in progress, should permit us to determine whether this remanence was acquired from a late lunar core dynamo. (1) Tikoo et al. (2012) Proc. Lunar Planet Sci. Conf. 43rd, #2691. (2) Gose et al. (1973) The Moon (7), p. 196-201.
Injury rates in children participating in taekwondo competition.

PubMed

Pieter, W; Zemper, E D

1997-07-01

To report rates of injuries sustained during Junior taekwondo competitions. Prospective. Data were collected with simple check-off forms that describe the athlete, nature, site, circumstances, and severity of the injury at three major taekwondo tournaments involving a total of 3,341 boys and 917 girls. No difference was found between boys (58.34/1,000 athlete-exposures) and girls (56.57/1,000 athlete-exposures) in total injury rate (p > 0.05). Collapsed over gender, significant differences (p = 0.013) in injury rates of body parts were found with the lower extremities (21.83/1,000 athlete-exposures) ranked first. Unblocked attacks are the major cause of injury in both boys and girls. Coaches are advised to work on the blocking skills of their Junior taekwondo athletes. No head contact for children in taekwondo competition should also be considered.
Evaluation of wintertime precipitation forecasts over the Australian Snowy Mountains

NASA Astrophysics Data System (ADS)

Huang, Yi; Chubb, Thomas; Sarmadi, Fahimeh; Siems, Steven T.; Manton, Michael J.; Franklin, Charmaine N.; Ebert, Elizabeth

2018-07-01

This study evaluates the Australian Community Climate and Earth-System Simulator (ACCESS) Numerical Weather Prediction system in forecasting precipitation across the Australian Snowy Mountains for two cool seasons. Metrics based on seasonal accumulated and daily precipitation show that the model is able to reproduce the observed domain-mean accumulated precipitation reasonably well (with a slight overestimation), but this is, in part, due to a compensation of various errors. Both the frequency and intensity of the heavy precipitation days (domain-mean daily precipitation >5 mm day-1) are overrepresented, particularly over the complex terrain and high-elevation areas, whereas the frequency of the very light precipitation days (domain-mean daily precipitation <1 mm day-1) is underestimated, primarily over lower-elevation areas both upwind and downwind of the mountains. Most of the precipitation is forecasted by the grid-scale precipitation scheme, with appreciable snowfalls predicted over the high elevations. The model also demonstrates appreciable skill in reproducing the synoptic regimes. The proportion of the forecast precipitation for each regime is comparable to the observations, although the orographic enhancement over the western slopes of the mountains is more pronounced in the forecasts, particularly for the wetter regimes. An examination on the effect of the lower-atmosphere stability suggests that most of the precipitation (50-70% over the high elevations) is produced under the "unblocked" condition, which is diagnosed 31% of the time. The remainder is produced under the "blocked" condition. Combined with a case study, potential sources of error associated with the forecast precipitation biases are also discussed.
Magnetic study of meteorites recovered in the Atacama desert (Chile): implications for meteorite paleomagnetism and the stability of hot desert surfaces (Invited)

NASA Astrophysics Data System (ADS)

Uehara, M.; Gattacceca, J.; Valenzuela, M.; Demory, F.; Rochette, P.

2010-12-01

Hot deserts are one of the large reservoirs of meteorites on Earth (about 25% of total meteorites), and some groups of rare meteorites (Rumuruti chondrites or lunar meteorites for instance). Therefore, the paleomagnetic record of hot desert meteorites is potentially a good source of information about the ancient extraterrestrial magnetic fields. However, meteorites recovered in hot deserts have typical terrestrial residence times (their so-called terrestrial ages) in the order of a few to several tens of kyr. During that time, a desert meteorite is exposed to the geomagnetic field, and is likely to acquire a Viscous Remanent Magnetization (VRM) whose intensity is controlled, among other things, by the stability of the desert surface. Moreover, with increasing terrestrial age, metallic and sulphide phases that are the dominant magnetic minerals in meteorites are oxidized and form potentially magnetic weathering minerals, resulting in the possible destruction of the primary remanence and acquisition of secondary terrestrial chemical remanence (CRM). Therefore, the paleomagnetic study of desert meteorites must take into account these terrestrial processes, in order to isolate the extraterrestrial magnetic record. We report here the paleomagnetic data obtained from 8 ordinary chondrites (3 H- and 5 L-chondrites) collected by our group in the Atacama desert (Chile) and oriented in situ with respect to the geographic north. Optical microscopy found that their weathering grades are W3 (60 - 95 % of metal is replaced by oxi-/hydroxides, 4 samples), W2 (moderate oxidation of metal, 20 - 60 % replaced; 2 samples), and W1 (only minor oxidation, 2 samples). Alternating field demagnetization experiments up to 100 mT found that W1 and W2 samples have a very low coercivity component (< 5 mT) and show unstable demagnetization paths above 10 mT, a behavior similar to that of freshly fallen ordinary chondrites. On the other hand, the more weathered samples (weathering stage W3) have medium to high coercivity components (20 ~ 100 mT) in addition to low coercivity components (<10mT). Thermal demagnetization experiments up to 300 °C found that W1 ~ W3 samples have low temperature components unblocked below 110 ~ 200 °C, which are plausibly VRM or CRM. Only W3 samples have directionally stable medium temperature component (150 ~ 300 °C or higher). In a given meteorite, the directions of mutually oriented samples are identical in W3 meteorites, but are scattered in W1 and W2 meteorites (like in most meteorite falls). These results indicate that the weathered samples (W3) have much more homogeneous and stable Natural Remanent Magnetizations than weakly weathered (W2 ~ W1) samples. Therefore, the W3 meteorites appear almost completely re-magnetized during terrestrial weathering. The directions of magnetization do no point toward the north, but the inclinations of the high temperature components of W3 samples are clustered around -40°, corresponding to the inclination of the average dipole field inclination at the find location. This suggests that the meteorites have moved on the desert surface by creeping movements.
Investigation of follicular and non-follicular pathways for polyarginine and oleic acid modified nanoparticles

PubMed Central

Hayden, Patrick; Singh, Mandip

2013-01-01

Purpose The aim of the current study was to investigate the percutaneous permeation pathways of cell penetrating peptide modified lipid nanoparticles and oleic acid modified polymeric nanoparticles. Methods Confocal microscopy was performed on skin cultures (EpiDermFT™) for modified and un-modified nanoparticles. Differential stripping was performed following in vitro skin permeation of Ibuprofen (Ibu) encapsulated nanoparticles to estimate Ibu levels in different skin layers and receiver compartment. The hair follicles (HF) were blocked and in vitro skin permeation of nanoparticles was then compared with unblocked HF. The surface modified nanoparticles were investigated for response on allergic contact dermatitis (ACD). Results Surface modified nanoparticles showed a significant higher (p < 0.05) in fluorescence in EpiDermFT™ cultures compared to controls. The HF play less than 5% role in total nanoparticle permeation into the skin. The Ibu levels were significantly high (p<0.05) for surface modified nanoparticles compared to controls. The Ibu levels in skin and receiver compartment were not significantly different when HF were open or closed. Modified nanoparticles showed significant improvement in treatment of ACD compared to solution. Conclusions Our studies demonstrate that increased skin permeation of surface modified nanoparticles is not only dependent on a follicular pathway but also occur through non-follicular pathway(s). PMID:23187866
Paleomagnetic and magnetic fabric studies of Lower Triassic red sandstones from the autochthonous cover of the Central Western Carpathians: new insights into paleogeographic setting and tectonic evolution of the area

NASA Astrophysics Data System (ADS)

Szaniawski, R.; Jankowski, L.; Ludwiniak, M.; Mazzoli, S.; Szczygieł, J.

2017-12-01

The Carpathian Mountains were formed through progressive collision and amalgamation of the Alcapa and Tisza-Dacia microplates with the European Platform. The Central Western Carpathians (CWC) tectonic unit analyzed in this study constitutes a fragment of the Alcapa microplate - research in this area is therefore of great importance in the context of the geotectonic evolution of the Carpathian orogen. Our paleomagnetic and magnetic fabric studies were focused on Lower Triassic red sandstones from the autochthonous cover of the crystalline basement. We present new results from three mountain massifs: Low Tatra, Velka Fatra and Strazovske Vrchy, comparing them with our earlier works performed in the Tatra Mts. Rockmagnetic studies reveal similar results in all four studied regions - the dominant ferromagnetic carrier in red sandstones is hematite, while the magnetic fabric is mostly controlled by paramagnetic minerals. AMS results outline a bedding parallel foliation and a tectonic lineation. This lineation lies in the bedding plane but is somewhat oblique to the present horizontal plane. The fact that the lineation is not exactly parallel to the strike of the beds is most likely due to multistage deformation: the lineation is related to bedding parallel shortening associated with the folding and thrusting stage, while present-day bedding attitude results at least partially from rotations associated with subsequent uplift and/or faulting. Paleomagnetic analysis indicate that hematite carrier records characteristic remanent component of high unblocking temperatures (680°C) and both normal (dominant) and reversed polarity. Paleomagnetic inclinations are similar to those expected from reference paleomagnetic data from the European Platform. Declination values are rather similar in all four studied areas and imply moderate counterclockwise rotations of the CWC. These results are incompatible with some of the previous paleomagnetic studies of younger rocks from the CWC suggesting large-scale counterclockwise rotations. Acknowledgements: this work was supported by Polish National Science Centre (NCN) (Grant nr. 2014/13/B/ST10/01151).
Paleomagnetism and Magnetostratigraphy of Upper Permian to Lower Triassic (?) Beaufort Group Strata at Bethulie, Karoo Basin, Free State Province, South Africa

NASA Astrophysics Data System (ADS)

Geissman, J. W.; Gastaldo, R. A.; Neveling, J.; Makubalo, S.

2017-12-01

A multifaceted approach to understand the timing of interpreted environmental changes during the Late Permian to possibly Early Triassic (?) time in the Beaufort Group strata of the Karoo Basin includes work to establish robust magnetic polarity records for sections previously interpreted to encompass end-Permian extinction events. Demonstrating the preservation of an early-acquired remanence (RM) in Karoo strata is required for a robust magnetostratigraphy. Yet, this is challenging due to thermochemical effects related to the Early Jurassic (ca. 183 Ma) Karoo Large Igneous Province (LIP), and the NE to SW increase in burial diagenesis attending Cape Fold Belt tectonism. Documentation of a primary RM in these strata, which appears to be preserved in some areas, requires careful laboratory- and field-based assessment. We report data from 53 sites collected at the well-studied Bethulie section, Free State Province, in which several <2 m wide Karoo LIP dikes crop out. We obtained 7-10+ independent samples per individual horizon to assess ChRM uniformity. Strata well-removed from dikes yield both normal and reverse polarity ChRM. It is always the case that the first-removed RM is a NNW seeking, moderate to steep negative-inclination ChRM (normal polarity); NRM intensities are typically 1 to 5 mA/m. Sites BT15 and BT21, which are located in strata lying some 4 m below the often-cited "event bed" interval inferred to be the terrestrial expression of the Permian/Triassic boundary, is dominated by a well-defined reverse RM with a normal overprint RM unblocked below 400oC, implying elevated temperatures (i.e., 100 to 250oC+) for ca. 1 Ma (+/-). Contact tests are positive but complicated. Host strata collected in distances equal to or less than 1-2 dike widths from the intrusions have been thermally remagnetized and demonstrate high NRM intensities (> 50 mA/m). Collectively, we interpret these data to indicate that any ChRM, with the exception of those from host strata in baked contacts, that persists above Tlub of 425oC is pre-Karoo LIP in origin, and likely primary at the Bethulie locality.
Paleomagnetism of the Chinle and Kayenta Formations, New Mexico and Arizona

NASA Astrophysics Data System (ADS)

Bazard, David R.; Butler, Robert F.

1991-06-01

Paleomagnetic data were obtained from 22 sites (6-10 samples/site) in the Upper Shale Member of the Chinle Formation, 43 sites in the Owl Rock Member of the Chinle Formation, and 35 sites in the Kayenta Formation. Thermal demagnetization and data analyses indicate that within-site dispersion is an important criterion for selecting sites which retain a high unblocking temperature characteristic remanent magnetization (ChRM). Site-mean directions define at least four antipodal polarity zones within each member/formation, suggesting the ChRM was acquired soon after deposition. Fifteen site-mean virtual geomagnetic poles (VGPs) from the Upper Shale Member of the Chinle Formation yield an early Norian paleomagnetic pole position of 57.4°N, 87.8°E (K = 60, A95 = 5.0°). Eighteen site-mean VGPs from the Owl Rock Member of the Chinle Formation yield a middle Norian paleomagnetic pole position of 56.5°N, 66.4°E (K = 183, A95 = 2.6°). Twenty-three site-mean VGPs from the Kayenta Formation yield a Pliensbachian pole position of 59.0°N, 66.6°E (K = 155, A95 = 2.4°). Combined with paleomagnetic poles from the Moenave Formation and the Shinarump Member of the Chinle Formation, these data record ˜30 m.y. of North American apparent polar wander (APW) within a regional stratigraphic succession. During the Camian and Norian stages of the Late Triassic, Chinle poles progress westward. During the Hettangian through Pliensbachian stages of the Early Jurassic, the pattern of APW changed to an eastward progression. Even after correction for 4° clockwise rotation of the Colorado Plateau, a sharp comer in the APW path (J1 cusp) is resolved near the pole from the Hettangian/Sinemurian (˜200 Ma) Moenave Formation (59.4°N, 59.2°E). Amongst other implications, the sharp change in the APW path at the J1 cusp implies an abrupt change from counterclockwise rotation of Pangea prior to 200 Ma to clockwise rotation thereafter.
Biological Evaluation of 99mTc-HYNIC-EDDA/tricine-(Ser)-D4 Peptide for Tumor Targeting.

PubMed

Kazemi, Ziba; Zahmatkesh, Mona Haddad; Abedi, Seyed Mohammad; Hosseinimehr, Seyed Jalal

2017-08-24

D4 small peptide (Leu-Ala-Arg-Leu-Leu-Thr) was selected as an appropriate agent for specific targeting of epidermal growth factor receptor (EGFR). The aim of study was to investigate the 99mTc-labeled D4 peptide for non-small cell lung tumor targeting. HYNIC-(Ser)3-D4 peptide was labeled with 99mTc using mixture of tricine and ethylenediamine diacetic acid (EDDA) as co-ligands. The in vitro cellular uptake of radiolabeled peptide was evaluated by blocking test on human non-small cell lung cancer (A-549) cell line and its biodistribution was evaluated in A-549 xenografted nude mice. This conjugated peptide was labeled with 99mTc in high radiochemical purity and it was highly stable in buffer and serum. The un-blocked to blocked cellular radioactivity ratio was 4- fold that showed a specific binding of this radiolabeled peptide on A-549 cell. Animal biodistribution in A-549 xenografted nude mice showed rapid clearance from blood and other non-target organs. Tumor uptake values as %ID/g (percentage of injection dose per gram of tissue) were 2.47% and 1.30% at 1 and 4 h after injection. This study showed the 99mTc-EDDA/tricine-HYNIC-(Ser)3-D4 peptide had tumor targeting on the non-small cell lung tumor. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.
Simultaneous fabrication of very high aspect ratio positive nano- to milliscale structures.

PubMed

Chen, Long Qing; Chan-Park, Mary B; Zhang, Qing; Chen, Peng; Li, Chang Ming; Li, Sai

2009-05-01

A simple and inexpensive technique for the simultaneous fabrication of positive (i.e., protruding), very high aspect (>10) ratio nanostructures together with micro- or millistructures is developed. The method involves using residual patterns of thin-film over-etching (RPTO) to produce sub-micro-/nanoscale features. The residual thin-film nanopattern is used as an etching mask for Si deep reactive ion etching. The etched Si structures are further reduced in size by Si thermal oxidation to produce amorphous SiO(2), which is subsequently etched away by HF. Two arrays of positive Si nanowalls are demonstrated with this combined RPTO-SiO(2)-HF technique. One array has a feature size of 150 nm and an aspect ratio of 26.7 and another has a feature size of 50 nm and an aspect ratio of 15. No other parallel reduction technique can achieve such a very high aspect ratio for 50-nm-wide nanowalls. As a demonstration of the technique to simultaneously achieve nano- and milliscale features, a simple Si nanofluidic master mold with positive features with dimensions varying continuously from 1 mm to 200 nm and a highest aspect ratio of 6.75 is fabricated; the narrow 200-nm section is 4.5 mm long. This Si master mold is then used as a mold for UV embossing. The embossed open channels are then closed by a cover with glue bonding. A high aspect ratio is necessary to produce unblocked closed channels after the cover bonding process of the nanofluidic chip. The combined method of RPTO, Si thermal oxidation, and HF etching can be used to make complex nanofluidic systems and nano-/micro-/millistructures for diverse applications.
Acquisition of chemical remanent magnetization during experimental ferrihydrite-hematite conversion in Earth-like magnetic field-implications for paleomagnetic studies of red beds

NASA Astrophysics Data System (ADS)

Jiang, Zhaoxia; Liu, Qingsong; Dekkers, Mark J.; Tauxe, Lisa; Qin, Huafeng; Barrón, Vidal; Torrent, José

2015-10-01

Hematite-bearing red beds are renowned for their chemical remanent magnetization (CRM). If the CRM was acquired substantially later than the sediment was formed, this severely compromises paleomagnetic records. To improve our interpretation of the natural remanent magnetization, the intricacies of the CRM acquisition process must be understood. Here, we contribute to this issue by synthesizing hematite under controlled 'Earth-like' field conditions (≲ 100 μ T). CRM was imparted in 90 oriented samples with varying inclinations. The final synthesis product appeared to be dominated by hematite with traces of ferrimagnetic iron oxides. When the magnetic field intensity is ≳ 40 μ T, the CRM records the field direction faithfully. However, for field intensities ≲ 40 μ T, the CRM direction may deviate considerably from that of the applied field during synthesis. The CRM intensity normalized by the isothermal remanent magnetization (CRM/IRM@2.5 T) increases linearly with the intensity of growth field, implying that CRM could potentially be useful for relative paleointensity studies if hematite particles of chemical origins have consistent properties. CRM in hematite has a distributed unblocking temperature spectrum from ∼200 to ∼650 °C, while hematite with a depositional remanent magnetization (DRM) has a more confined spectrum from ∼ 600to 680 °C because it is usually coarser-grained and more stoichiometric. Therefore, the thermal decay curves of CRM with their concave shape are notably different from their DRM counterparts which are convex. These differences together are suggested to be a potential discriminator of CRM from DRM carried by hematite in natural red beds, and of significance for the interpretation of paleomagnetic studies on red beds.
Can a primary remanence be retrieved from partially remagnetized Eocence volcanic rocks in the Nanmulin Basin (southern Tibet) to date the India-Asia collision?

NASA Astrophysics Data System (ADS)

Huang, Wentao; Dupont-Nivet, Guillaume; Lippert, Peter C.; van Hinsbergen, Douwe J. J.; Dekkers, Mark J.; Guo, Zhaojie; Waldrip, Ross; Li, Xiaochun; Zhang, Xiaoran; Liu, Dongdong; Kapp, Paul

2015-01-01

Paleomagnetic dating of the India-Asia collision hinges on determining the Paleogene latitude of the Lhasa terrane (southern Tibet). Reported latitudes range from 5°N to 30°N, however, leading to contrasting paleogeographic interpretations. Here we report new data from the Eocene Linzizong volcanic rocks in the Nanmulin Basin, which previously yielded data suggesting a low paleolatitude ( 10°N). New zircon U-Pb dates indicate an age of 52 Ma. Negative fold tests, however, demonstrate that the isolated characteristic remanent magnetizations, with notably varying inclinations, are not primary. Rock magnetic analyses, end-member modeling of isothermal remanent magnetization acquisition curves, and petrographic observations are consistent with variable degrees of posttilting remagnetization due to low-temperature alteration of primary magmatic titanomagnetite and the formation of secondary pigmentary hematite that unblock simultaneously. Previously reported paleomagnetic data from the Nanmulin Basin implying low paleolatitude should thus not be used to estimate the time and latitude of the India-Asia collision. We show that the paleomagnetic inclinations vary linearly with the contribution of secondary hematite to saturation isothermal remanent magnetization. We tentatively propose a new method to recover a primary remanence with inclination of 38.1° (35.7°, 40.5°) (95% significance) and a secondary remanence with inclination of 42.9° (41.5°,44.4°) (95% significance). The paleolatitude defined by the modeled primary remanence—21°N (19.8°N, 23.1°N)—is consistent with the regional compilation of published results from pristine volcanic rocks and sedimentary rocks of the upper Linzizong Group corrected for inclination shallowing. The start of the Tibetan Himalaya-Asia collision was situated at 20°N and took place by 50 Ma.
Magnetic particle capture for biomagnetic fluid flow in stenosed aortic bifurcation considering particle-fluid coupling

NASA Astrophysics Data System (ADS)

Bose, Sayan; Banerjee, Moloy

2015-07-01

Magnetic nanoparticles drug carriers continue to attract considerable interest for drug targeting in the treatment of cancer and other pathological conditions. Guiding magnetic iron oxide nanoparticles with the help of an external magnetic field to its target is the basic principle behind the Magnetic Drug Targeting (MDT). It is essential to couple the ferrohydrodynamic (FHD) and magnetohydrodynamic (MHD) principles when magnetic fields are applied to blood as a biomagnetic fluid. The present study is devoted to study on MDT technique by particle tracking in the presence of a non uniform magnetic field in a stenosed aortic bifurcation. The present numerical model of biomagnetic fluid dynamics (BFD) takes into accounts both magnetization and electrical conductivity of blood. The blood flow in the bifurcation is considered to be incompressible and Newtonian. An Eulerian-Lagrangian technique is adopted to resolve the hemodynamic flow and the motion of the magnetic particles in the flow using ANSYS FLUENT two way particle-fluid coupling. An implantable infinitely long cylindrical current carrying conductor is used to create the requisite magnetic field. Targeted transport of the magnetic particles in a partly occluded vessel differs distinctly from the same in a regular unblocked vessel. Results concerning the velocity and temperature field indicate that the presence of the magnetic field influences the flow field considerably and the disturbances increase as the magnetic field strength increases. The insert position is also varied to observe the variation in flow as well as temperature field. Parametric investigation is conducted and the influence of the particle size (dp), flow Reynolds number (Re) and external magnetic field strength (B0) on the "capture efficiency" (CE) is reported. The difference in CE is also studied for different particle loading condition. According to the results, the magnetic field increased the particle concentration in the target region. Analysis shows that there exists an optimum regime of operating parameters for which deposition of the drug carrying magnetic particles in a target zone on the partly occluded vessel wall can be maximized. The results provide useful design bases for in vitro set up for the investigation of MDT in stenosed blood vessels.
Quaternary remagnetization of the Neoproterozoic limestone of Negash Synclinorium (Arabian-Nubian Shield, northern Ethiopia): With implications of no paleomagnetic testing for the proposed Snowball Earth events

NASA Astrophysics Data System (ADS)

Kidane, Tesfaye; Bachtadse, Valerian; Alene, Mulugeta

2014-10-01

Eighty-one paleomagnetic cores were collected from 10 locations across a black limestone unit within the core of Negash Synclinorium, northern Ethiopia in order to test the proposed Snowball Earth events for the diamictite unit of the Tambien Group. Cores were cut into two standard paleomagnetic specimens and were subjected to stepwise demagnetizations using both Thermal (TH) and alternating field (AF) techniques. Rock magnetic analyses on representative specimens were done and results revealed goethite, pyrrhotite, titano-magnetite, and titano-hematite to be the major magnetic materials carrying the magnetizations with PSD (pseudo single domain) grain size range. In most cases paleomagnetic directions are defined by a single component of magnetization, where a viscous component is present it is usually removed by heating to a temperature of ∼200 °C or an AF of ∼10 mT. The high stability component isolated above temperature of 200 °C or AF of 15 mT, defined straight line trajectories directed towards the origin and considered as the Characteristic Remanent Magnetization Direction (ChRM). The direction of magnetization of the ChRM is determined for samples with stable straight line segments by the best-fit line using the least square technique of Kirschvink (1980). In the cases of overlapping spectra and unblocking temperatures, direction of magnetization is determined by remagnetization circles of Halls (1976, 1978). When site mean ChRM directions are plotted on stereogram, their distribution is relatively clustered in geographic coordinates and the overall mean direction is Decg = 358.5°, Incg = 16.6° (α95 = 3.8°, K = 162.8, N = 10). After a structural restoration to the horizontal is made the directions disperse and fail the fold test of both McElhinny’s and McFadden’s tests and the mean direction is Decs = 353.5°, Incs = 8.8° (α95 = 18.9°, K = 7.5, N = 10). This is interpreted to result from a later remagnetization of the black limestone. All directions are normal in polarity and have mean unrestored paleomagnetic directions comparable to the Quaternary paleomagnetic directions. Virtual Geomagnetic poles (VGP) in the unrestored position is used to calculate overall mean VGP position resulting long = 235.7°E, latg = 84.5°N (A95 = 3.0°, N = 10). Comparison of the obtained pole with the apparent polar wander path (APWP) curve for Africa of Besse and Courtillot (1991, 2003) and with the 2 Ma reference pole of stable Africa (Kidane et al., 2003) is found to be consistent with remagnetizations during the Quaternary period. Hence supporting evidence for the proposed Snowball Earth event of the Sturtian glaciation in the Negash rocks could not, unfortunately, be obtained from paleomagnetism.
Mask-Assisted Seeded Growth of Segmented Metallic Heteronanostructures

DOE PAGES

Crane, Cameron C.; Tao, Jing; Wang, Feng; ...

2014-12-04

Controlling the deposition of exotic metals in the seeded growth of multi-metal nanostructures is challenging. This work describes a seeded growth method assisted by a mask for synthesis of segmented binary or ternary metal nanostructures. Silica is used as a mask to partially block the surface of a seed and a second metal is subsequently deposited on the exposed area, forming a bimetallic heterodimer. The initial demonstration was carried out on a Au seed, followed by deposition of Pd or Pt on the seed. It was found that Pd tends to spread out laterally on the seed while Pt inclinesmore » to grow vertically into branched topology on Au. Without removal of the SiO₂ mask, Pt could be further deposited on the unblocked Pd of the Pd-Au dimer to form a Pt-Pd-Au trimer. The mask-assisted seeded growth provides a general strategy to construct segmented metallic nanoarchitectures.« less
DOE Office of Scientific and Technical Information (OSTI.GOV)

Crane, Cameron C.; Tao, Jing; Wang, Feng

Controlling the deposition of exotic metals in the seeded growth of multi-metal nanostructures is challenging. This work describes a seeded growth method assisted by a mask for synthesis of segmented binary or ternary metal nanostructures. Silica is used as a mask to partially block the surface of a seed and a second metal is subsequently deposited on the exposed area, forming a bimetallic heterodimer. The initial demonstration was carried out on a Au seed, followed by deposition of Pd or Pt on the seed. It was found that Pd tends to spread out laterally on the seed while Pt inclinesmore » to grow vertically into branched topology on Au. Without removal of the SiO₂ mask, Pt could be further deposited on the unblocked Pd of the Pd-Au dimer to form a Pt-Pd-Au trimer. The mask-assisted seeded growth provides a general strategy to construct segmented metallic nanoarchitectures.« less
Studies of the chemical basis of the origin of protein synthesis Initiation and direction of peptide growth

NASA Technical Reports Server (NTRS)

Mullins, D. W., Jr.; Lacey, J. C., Jr.

1980-01-01

The data presented in this paper show that the ease of nonenzymatic activation of carboxylic acids by ATP at pH 5 varies directly with the pKa of the carboxyl group, and is consistent with the idea that it is the protonated form of the carboxyl group which participates in the activation reaction. Consequently, since most N-blocked amino acids have higher pKas than do their unblocked forms, they are activated more readily, and it has been demonstrated that this principle applies to peptides as well, which are activated more rapidly than single amino acids. It is proposed that this fact may be partly responsible for the origin of two important features still observed in contemporary protein synthesis: (1) initiation in prokaryotes is accomplished with an N-blocked amino acid, and (2) elongation in all living systems occurs at the carboxyl end of the growing peptide.

Automatic Blocked Roads Assessment after Earthquake Using High Resolution Satellite Imagery

NASA Astrophysics Data System (ADS)

Rastiveis, H.; Hosseini-Zirdoo, E.; Eslamizade, F.

2015-12-01

In 2010, an earthquake in the city of Port-au-Prince, Haiti, happened quite by chance an accident and killed over 300000 people. According to historical data such an earthquake has not occurred in the area. Unpredictability of earthquakes has necessitated the need for comprehensive mitigation efforts to minimize deaths and injuries. Blocked roads, caused by debris of destroyed buildings, may increase the difficulty of rescue activities. In this case, a damage map, which specifies blocked and unblocked roads, can be definitely helpful for a rescue team. In this paper, a novel method for providing destruction map based on pre-event vector map and high resolution world view II satellite images after earthquake, is presented. For this purpose, firstly in pre-processing step, image quality improvement and co-coordination of image and map are performed. Then, after extraction of texture descriptor from the image after quake and SVM classification, different terrains are detected in the image. Finally, considering the classification results, specifically objects belong to "debris" class, damage analysis are performed to estimate the damage percentage. In this case, in addition to the area objects in the "debris" class their shape should also be counted. The aforementioned process are performed on all the roads in the road layer.In this research, pre-event digital vector map and post-event high resolution satellite image, acquired by Worldview-2, of the city of Port-au-Prince, Haiti's capital, were used to evaluate the proposed method. The algorithm was executed on 1200×800 m2 of the data set, including 60 roads, and all the roads were labelled correctly. The visual examination have authenticated the abilities of this method for damage assessment of urban roads network after an earthquake.
Multiple paleotsunamis inferred from a single coral boulder (Invited)

NASA Astrophysics Data System (ADS)

Goto, K.; Nakamura, N.; Sato, T.; Hisamatsu, A.

2013-12-01

Tsunami boulders are important geological evidence of paleotsunamis. Recent advance in field observation, laboratory analyses and numerical modeling on coastal boulders have greatly improved our knowledge regarding to their depositional process. For example, in the southern Ryukyu Islands, Japan, radiocarbon dating of many coral boulders were performed and the recurrence interval of the paleotsunamis was estimated [Araoka et al., 2013 Geology]. Their preferential distributions in specific area would also suggest local occurrence of tsunamigenic earthquakes [Goto et al., 2013 Geology]. These types of works can be conducted at the place where many boulders exist and any type of dating methods are applicable to estimate their depositional ages. On the other hand, there are many isolated boulders in the world and their depositional ages were sometimes uncertain. Therefore, it is highly required developing a methodology to use such isolated boulders not just to use it as evidence of paleotsunamis but to know more details such as timing and size of tsunami. In order to overcome this issue, we introduce an advanced methodology based on the paleomagnetism as well as the numerical modeling. Rocks possess a remanent magnetization parallel to the Earth's magnetic field at the time of rock formation. When boulders are rotated or overturned by the paleotsunami from their original locations, a new component of viscous remanent magnetization (VRM) is added on an original component parallel to the Earth's magnetic field. The VRM acquired at low temperature during a long time scale in nature can be demagnetized at high temperature in a short time in laboratory. Therefore, the demagnetizing (unblocking) temperature of VRM gives a transportation mode and also its timing for the transportation histories from a single boulder [Sato et al., 2013 AOGS abstract]. We applied this method to a large coral boulder at 10 m in elevation at Ishigaki Island, Japan, which was deposited around 2000BP according to the radiocarbon dating [e.g., Goto et al., 2010 Earth-Science Reviews]. The Ishigaki Island was frequently affected by large tsunamis in the past including the recent AD1771 event (~30 m in run-up height) but this boulder was probably not moved by the AD1771 tsunami according to the interpretation of historical document. It is interesting to note that magnetic analyses revealed that this boulder was rotated twice prior to the AD1771 event. Numerical modeling for boulder transport further revealed that one large tsunami whose size is equivalent to the AD1771 event is insufficient to deposit this boulder to its present position from the presumed original position. However, if another tsunami with same size further affected to this boulder, which was once reached to the shore by the former tsunami, then it was reached close to the present position [Hisamatsu et al., 2013 AGU abstract]. Combining the results obtained from paleomagnetic analysis and numerical modeling, we infer that multiple large tsunamis including the AD1771 event was probably occurred during last 2000BP at Ishigaki Island based only on the analyses of this single coral boulder. Although further improvement is required, our methodology may be applied to many possible paleotsunami boulders in the world including isolated ones to unravel their transportation histories that may imply the number and size of tsunamis affected to the boulder in the past.
The electrical response of turtle cones to flashes and steps of light.

PubMed

Baylor, D A; Hodgkin, A L; Lamb, T D

1974-11-01

1. The linear response of turtle cones to weak flashes or steps of light was usually well fitted by equations based on a chain of six or seven reactions with time constants varying over about a 6-fold range.2. The temperature coefficient (Q(10)) of the reciprocal of the time to peak of the response to a flash was 1.8 (15-25 degrees C), corresponding to an activation energy of 10 kcal/mole.3. Electrical measurements with one internal electrode and a balancing circuit gave the following results on red-sensitive cones of high resistance: resistance across cell surface in dark 50-170 MOmega; time constant in dark 4-6.5 msec. The effect of a bright light was to increase the resistance and time constant by 10-30%.4. If the cell time constant, resting potential and maximum hyperpolarization are known, the fraction of ionic channels blocked by light at any instant can be calculated from the hyperpolarization and its rate of change. At times less than 50 msec the shape of this relation is consistent with the idea that the concentration of a blocking molecule which varies linearly with light intensity is in equilibrium with the fraction of ionic channels blocked.5. The rising phase of the response to flashes and steps of light covering a 10(5)-fold range of intensities is well fitted by a theory in which the essential assumptions are that (i) light starts a linear chain of reactions leading to the production of a substance which blocks ionic channels in the outer segment, (ii) an equilibrium between the blocking molecules and unblocked channels is established rapidly, and (iii) the electrical properties of the cell can be represented by a simple circuit with a time constant in the dark of about 6 msec.6. Deviations from the simple theory which occur after 50 msec are attributed partly to a time-dependent desensitization mechanism and partly to a change in saturation potential resulting from a voltage-dependent change in conductance.7. The existence of several components in the relaxation of the potential to its resting level can be explained by supposing that the ;substance' which blocks light sensitive ionic channels is inactivated in a series of steps.
Changes in permeability caused by transient stresses: field observations, experiments, and mechanisms

USGS Publications Warehouse

Manga, Michael; Beresnev, Igor; Brodsky, Emily E.; Elkhoury, Jean E.; Elsworth, Derek; Ingebritsen, Steve E.; Mays, David C.; Wang, Chi-Yuen

2012-01-01

Oscillations in stress, such as those created by earthquakes, can increase permeability and fluid mobility in geologic media. In natural systems, strain amplitudes as small as 10–6 can increase discharge in streams and springs, change the water level in wells, and enhance production from petroleum reservoirs. Enhanced permeability typically recovers to prestimulated values over a period of months to years. Mechanisms that can change permeability at such small stresses include unblocking pores, either by breaking up permeability-limiting colloidal deposits or by mobilizing droplets and bubbles trapped in pores by capillary forces. The recovery time over which permeability returns to the prestimulated value is governed by the time to reblock pores, or for geochemical processes to seal pores. Monitoring permeability in geothermal systems where there is abundant seismicity, and the response of flow to local and regional earthquakes, would help test some of the proposed mechanisms and identify controls on permeability and its evolution.
Hydrogel-Forming Microneedle Arrays for Enhanced Transdermal Drug Delivery

PubMed Central

Donnelly, Ryan F; Singh, Thakur Raghu Raj; Garland, Martin J; Migalska, Katarzyna; Majithiya, Rita; McCrudden, Cian M; Kole, Prashant Laxman; Mahmood, Tuan Mazlelaa Tuan; McCarthy, Helen O; Woolfson, A David

2012-01-01

Unique microneedle arrays prepared from crosslinked polymers, which contain no drug themselves, are described. They rapidly take up skin interstitial fluid upon skin insertion to form continuous, unblockable, hydrogel conduits from attached patch-type drug reservoirs to the dermal microcirculation. Importantly, such microneedles, which can be fabricated in a wide range of patch sizes and microneedle geometries, can be easily sterilized, resist hole closure while in place, and are removed completely intact from the skin. Delivery of macromolecules is no longer limited to what can be loaded into the microneedles themselves and transdermal drug delivery is now controlled by the crosslink density of the hydrogel system rather than the stratum corneum, while electrically modulated delivery is also a unique feature. This technology has the potential to overcome the limitations of conventional microneedle designs and greatly increase the range of the type of drug that is deliverable transdermally, with ensuing benefits for industry, healthcare providers and, ultimately, patients. PMID:23606824
An exact arithmetic toolbox for a consistent and reproducible structural analysis of metabolic network models

PubMed Central

Chindelevitch, Leonid; Trigg, Jason; Regev, Aviv; Berger, Bonnie

2014-01-01

Constraint-based models are currently the only methodology that allows the study of metabolism at the whole-genome scale. Flux balance analysis is commonly used to analyse constraint-based models. Curiously, the results of this analysis vary with the software being run, a situation that we show can be remedied by using exact rather than floating-point arithmetic. Here we introduce MONGOOSE, a toolbox for analysing the structure of constraint-based metabolic models in exact arithmetic. We apply MONGOOSE to the analysis of 98 existing metabolic network models and find that the biomass reaction is surprisingly blocked (unable to sustain non-zero flux) in nearly half of them. We propose a principled approach for unblocking these reactions and extend it to the problems of identifying essential and synthetic lethal reactions and minimal media. Our structural insights enable a systematic study of constraint-based metabolic models, yielding a deeper understanding of their possibilities and limitations. PMID:25291352
Extraordinary light transmission through opaque thin metal film with subwavelength holes blocked by metal disks.

PubMed

Li, Wen-Di; Hu, Jonathan; Chou, Stephen Y

2011-10-10

We observed that when subwavelength-sized holes in an optically opaque metal film are completely covered by opaque metal disks larger than the holes, the light transmission through the holes is not reduced, but rather enhanced. Particularly we report (i) the observation of light transmission through the holes blocked by the metal disks up to 70% larger than the unblocked holes; (ii) the observation of tuning the light transmission by varying the coupling strength between the blocking disks and the hole array, or by changing the size of the disks and holes; (iii) the observation and simulation that the metal disk blocker can improve light coupling from free space to a subwavelength hole; and (iv) the simulation that shows the light transmission through subwavelength holes can be enhanced, even though the gap between the disk and the metal film is partially connected with a metal. We believe these finding should have broad and significant impacts and applications to optical systems in many fields.
CCSVI and MS: no meaning, no fact.

PubMed

Baracchini, Claudio; Atzori, Matteo; Gallo, Paolo

2013-03-01

A condition called "chronic cerebrospinal venous insufficiency" (CCSVI) has been postulated to play a role in the pathogenesis of multiple sclerosis (MS). This hypothesis implies that a complex pattern of extracranial venous stenosis determines a venous reflux into the brain of MS patients, followed by increased intravenous pressure, blood-brain barrier breakdown and iron deposition into the brain parenchyma, thus triggering a local inflammatory response. In this review, we critically analyze the scientific basis of CCSVI, the current literature on the relationship between CCSVI and MS, as well as the ultrasound methodology that has been claimed to provide evidence of impaired cerebral venous drainage. We show that no piece of the CCSVI theory has a solid supportive scientific evidence. The CCSVI appears to be a rather alien condition and its existence should be definitely questioned. Finally, no proven (i.e., based on strict scientific methodology and on the rules of evidence-based medicine) therapeutic effect of the "liberation" procedure (unblocking the extracranial venous obstruction using angioplasty) has been shown up to date.
How to resolve microsecond current fluctuations in single ion channels: The power of beta distributions

PubMed Central

Schroeder, Indra

2015-01-01

Abstract A main ingredient for the understanding of structure/function correlates of ion channels is the quantitative description of single-channel gating and conductance. However, a wealth of information provided from fast current fluctuations beyond the temporal resolution of the recording system is often ignored, even though it is close to the time window accessible to molecular dynamics simulations. This kind of current fluctuations provide a special technical challenge, because individual opening/closing or blocking/unblocking events cannot be resolved, and the resulting averaging over undetected events decreases the single-channel current. Here, I briefly summarize the history of fast-current fluctuation analysis and focus on the so-called “beta distributions.” This tool exploits characteristics of current fluctuation-induced excess noise on the current amplitude histograms to reconstruct the true single-channel current and kinetic parameters. A guideline for the analysis and recent applications demonstrate that a construction of theoretical beta distributions by Markov Model simulations offers maximum flexibility as compared to analytical solutions. PMID:26368656
Operational durability of a giant ER valve for Braille display

NASA Astrophysics Data System (ADS)

Luning, Xu; Han, Li; Yufei, Li; Shen, Rong; Kunquan, Lu

2017-05-01

The compact configuration of giant ER (electrorheological) valves provides the possibility of realizing a full-page Braille display. The operational durability of ER valves is a key issue in fulfilling a Braille display. A giant ER valve was used to investigate the variations in pressure drops and critical pressure drops of the valves over a long period under some typical operational parameters. The results indicate that neither the pressure drops nor critical pressure drops of giant ER valves show apparent deterioration over a long period. Without ER fluid exchange, a blockage appears in the channel of the valve because the ER structures induced by an external electric field cannot be broken by the Brownian motion of hydraulic oil molecules when the external electric field is removed. Forcing ER fluid flow is an effective and necessary method to keep the channel of the valve unblocked. Thus the operational durability of the valve using giant ER fluids is able to meet the demands of Braille display.
The Hadean to Paleoarchean geodynamo: microconglomerate tests from siliciclastic metasedimentary rocks from the Southern Cross Terrane of Western Australia

NASA Astrophysics Data System (ADS)

Cottrell, R. D.; Tarduno, J. A.; Bono, R. K.; Thern, E. R.; Chhibber, S. K.

2016-12-01

Detrital zircons found within metasedimentary rocks of the Yilgarn Craton (Western Austrlia) contain information about the early history of the geodynamo. Recently reported single crystal paleointensity (SCP) values obtained from zircon grains of the Jack Hills (JH) belt (Tarduno et al., 2015) suggest the presence of a core dynamo to times as old as 4.2 Ga. Magnetizations carried by zircons within these rocks have been preserved despite multiple reheating events of the host metasedimentary unit. Two positive conglomerate tests (Tarduno and Cottrell, 2013; Tarduno et al., 2015) as well as interlaboratory studies reproducing a prior positive conglomerate test (Dare et al., 2015; 2016) attest to the primary nature of the remanence carried by these zircons. Moreover, new Li data limit heating after zircon formation to < 500 oC. Similarly, the metasedimentary rocks of the Southern Cross Terrane, more than 400 kilometers away from the Discovery Site of the Jack Hills, contain detrital Eoarchean to Hadean age zircons (Nelson, 2005; Wyche, 2007). Following Tarduno et al. (2015), a micro-conglomerate test of oriented, small ( 500-700 mm) samples centered on single zircons ( 200-350 mm) was performed using the University of Rochester's ultra-high resolution 3-component DC SQUID magnetometer that affords an order of magnitude greater sensitivity than other high-resolution SQUID rock magnetometers. The characteristic remanences from oriented zircons (N=10; R=0.81) that unblock between 565 and 580 °C, consistent with a magnetite carrier, are well defined but together cannot be distinguished from those drawn from a random distribution (Ro=5.03) at the 95% confidence level; this indicates a positive microconglomerate test. Preliminary paleointensity determinations range between 4-27 μT. Additional studies of hand samples from the Southern Cross Terrane are underway.
Absolute Geomagnetic Paleointensity as Recorded by Mafic Dykes of the ~1.98 Ga Bundelkhand Swarm and ~0.75 Ga Malani Igneous Suite from Northern India

NASA Astrophysics Data System (ADS)

Piispa, E. J.; Smirnov, A. V.; Pandit, M. K.

2012-12-01

Determining the long-term behavior and configuration of the Precambrian geomagnetic field is crucial for understanding the origin and nature of Earth's early geodynamo. However, our knowledge about strength and morphology of the Precambrian geomagnetic field is extremely limited due to paucity of reliable data on the ancient field strength (paleointensity). Information correlating the strength and characteristics of Earth's ancient geomagnetic field can be gained by measuring the paleodirectional and paleointensity properties of Precambrian rocks. We investigated two Proterozoic mafic dyke swarms from the Indian subcontinent: the extensive NW-SE trending 1979±8 Ma (U-Pb) dyke swarm in the Bundelkhand craton and the N-S trending Malani mafic dyke swarm, the latter representing the third and final phase of magmatism in the Malani Igneous Suite. Malani rhyolites have been precisely dated at 771±2 to 751±3 Ma (U - Pb zircon ages). The Malani mafic dykes have been correlated with the ~750 Ma dolerite dykes of Seychelles based on geological and geochemical criteria. The mafic dykes of both studied swarms are vertical to sub-vertical and show little or no evidence of alteration. Detailed paleomagnetic studies, using both thermal and alternating field demagnetization, revealed the presence of stable dual-polarity magnetic component for both dyke swarms. The primary nature of the magnetization is supported by positive baked contact tests. Typically, the characteristic magnetization is single component with narrow unblocking temperature spectra between ~500°C and 550-570°C, with remanence carried by small PSD magnetite or low-Ti titanomagnetite. Absolute paleointensities of these dyke swarms were obtained by two different heating based methods: multiple specimen domain-state corrected (MSP-DSC) and Thellier double heating method with alternating infield-zerofield (IZ) and zerofield-infield (ZI) steps. The multiple sample protocol incorporated checks for alteration, additivity and reciprocity during heating. The magnetic stability of samples was checked using thermomagnetic curves and by monitoring the magnetic susceptibility changes through the paleointensity experiments. Magnetization measurements before and after low temperature demagnetization (LTD) in liquid nitrogen allowed comparison of the effectiveness of the LTD treatment with other experimental domain state corrections. We will discuss implications of our results for the Precambrian geomagnetic field evolution.
Paleomagnetism and magnetic fabric of the Triassic rocks from Spitsbergen

NASA Astrophysics Data System (ADS)

Dudzisz, K.; Szaniawski, R.; Michalski, K.; Manby, G.

2017-12-01

Understanding the origin and directions of the natural remanent magnetization and the tectonic deformation pattern reflected in magnetic fabric is of importance for investigation of the West Spitsbergen Fold and Thrust Belt (WSFTB) and its foreland. Previous research carried out on Triassic rocks from the study area concluded that these rocks record a composite magnetization of both, normal and reverse polarity, consisting of a primary Triassic remanence that is overlapped by a secondary post-folding component. Standard paleomagnetic procedures were conducted in order to determine the remanence components and a low-field AMS was applied to assess the degree and pattern of deformation. The AMS results from the WSFTB reveal a magnetic foliation that parallels the bedding planes and a dominantly NNW-SSE oriented magnetic lineation that is sub-parallel to the regional fold axial trend. These results imply a low to moderate degree of deformation and a maximum strain orientation parallel to that of the fold belt. These data are consistent with an orthogonal convergence model for the WSFTB formation. In turn, the magnetic fabric on the undeformed foreland displays a distinct NNE-SSW orientation that we attribute to the paleocurrent direction. Rock-magnetic analyses reveal that the dominant ferrimagnetic carriers are magnetite and titanomagnetite. The Triassic rocks are characterised by complicated NRM patterns often with overlapping unblocking temperature spectra of particular components. The dominant magnetisation is characterised, however, by a steep inclination of 70-80º. The derived paleomagnetic direction from the WSFTB falls on the Jurassic - recent sector of the apparent polar wander path (APWP) of Baltica after tectonic unfolding. These data imply that at least some of the identified secondary components could have originated before the Eurekan folding event (K/Pg), for example, in Early Cretaceous time which corresponds to the period of rifting events on Barents Sea and emplacement of dolerite intrusions. In contrast, paleomagnetic data from the foreland coincides with the APWP for Triassic - recent sector and partly matches previously published data.
Paleomagnetism of the Cretaceous Galula Formation and implications for vertebrate evolution

NASA Astrophysics Data System (ADS)

Widlansky, Sarah J.; Clyde, William C.; O'Connor, Patrick M.; Roberts, Eric M.; Stevens, Nancy J.

2018-03-01

This study uses magnetostratigraphy to help constrain the age of the paleontologically important Galula Formation (Rukwa Rift Basin, southwestern Tanzania). The formation preserves a Cretaceous vertebrate fauna, including saurischian dinosaurs, a putative gondwanatherian mammal, and notosuchian crocodyliforms. With better dating, the Galula Formation and its fossils help fill a temporal gap in our understanding of vertebrate evolution in continental Africa, enabling better evaluation of competing paleobiogeographic hypotheses concerning faunal exchange throughout Gondwana during the Cretaceous. Paleomagnetic samples for this study were collected from the Namba (higher in section) and Mtuka (lower in section) members of the Galula Formation and underwent stepwise thermal demagnetization. All samples displayed a strong normal magnetic polarity overprint, and maximum unblocking temperatures at approximately 690 °C. Three short reversed intervals were identified in the Namba Member, whereas the Mtuka Member lacked any clear reversals. Given the relatively limited existing age constraints, one interpretation correlates the Namba Member to Chron C32. An alternative correlation assigns reversals in the Namba Member to recently proposed short reversals near the end of the Cretaceous Normal Superchron (Chron C34), a time that is traditionally interpreted as having stable normal polarity. The lack of reversals in the Mtuka Member supports deposition within Chron C34. These data suggest that the Namba Member is no older than Late Cretaceous (Cenomanian-Campanian), with the Mtuka Member less well constrained to the middle Cretaceous (Aptian-Cenomanian). The paleomagnetic results are supported by the application of fold and reversal tests for paleomagnetic stability, and paleomagnetic poles for the Namba (246.4°/77.9°, α95 5.9°) and Mtuka (217.1°/72.2°, α95 11.1°) members closely matching the apparent polar wander path for Africa during the Late Cretaceous. These results confidently indicate a Late Creteceous age assignment for the Namba Member of the Galula Formation, a unit that has yielded key crocodyliform (e.g., Pakasuchus; Rukwasuchus) and dinosaur (e.g., Rukwatitan; Shingopana) fossils from eastern Africa.
Geometrical constraint on the localization of deep water formation

NASA Astrophysics Data System (ADS)

Ferreira, D.; Marshall, J.

2008-12-01

That deep water formation occurs in the North Atlantic and not North Pacific is one of the most notable features of the present climate. In an effort to build a system able to mimic such basic aspects of climate using a minimal description, we study here the influence of ocean geometry on the localization of deep water formation. Using the MIT GCM, two idealized configurations of an ocean-atmosphere-sea ice climate system are studied: Drake and Double-Drake. In Drake, one narrow barrier extends from the North Pole to 35°S while, in Double-Drake, two such barriers set 90° apart join at the North Pole to delimit a Small and a Large basin. Despite the different continental configurations, the two climates are strikingly similar in the zonal average (almost identical heat and fresh water transports, and meridional overturning circulation). However, regional circulations in the Small and Large basins exhibit distinctive Atlantic-like and Pacific-like characteristics: the Small basin is warmer and saltier than the Large one, concentrates dense water formation and deep overturning circulation and achieve the largest fraction of the northward ocean heat transport. We show that the warmer temperature and higher evaporation over the Small basin is not its distinguishing factor. Rather, it is the width of the basin in relation to the zonal fetch of the precipitation pattern. This generates a deficit/excess of precipitation over the Small/Large basin: a fraction of the moisture evaporated from the Small basin is transported zonally and rains out over the Large basin. This creates a salt contrast between the 2 basins, leading to the localization of deep convection in the salty Small basin. Finally, given on the broad similarities between the Double-Drake and real World, we suggest that many gross features that define the present climate are a consequence of 2 asymmetries: a meridional asymmetry (a zonally unblocked southern/blocked northern ocean) and a zonal one (a small and a large basin in the northern hemisphere).
Updated paleomagnetic pole from Cretaceous plutonic rocks of the Sierra Nevada, California: Tectonic displacement of the Sierra Nevada block

USGS Publications Warehouse

Hillhouse, John W.; Gromme, Sherman

2011-01-01

We report remanent magnetization measurements from 13 sites in Cretaceous plutonic rocks in the northern Sierra Nevada (38°N–39.5°N). By increasing the number of available paleomagnetic sites, the new data tighten constraints on the displacement history of the Sierra Nevada block and its pre-extensional position relative to interior North America. We collected samples in freshly exposed outcrops along four highway transects. The rocks include diorite, granodiorite, and tonalite with potassium-argon ages (hornblende) ranging from 100 Ma to 83 Ma. By combining our results with previous paleomagnetic determinations from the central and southern Sierra Nevada (excluding sites from the rotated southern tip east of the White Wolf–Kern Canyon fault system), we find a mean paleomagnetic pole of 70.5°N, 188.2°E, A95 = 2.6° (N = 26, Fisher concentration parameter, K = 118). Thermal demagnetization indicates that the characteristic remanence is generally unblocked in a narrow range within 35 °C of the Curie temperature of pure magnetite. Small apparent polar wander during the Cretaceous normal-polarity superchron, plus prolonged acquisition of remanence at the site level, may account for the low dispersion of virtual geomagnetic poles and relatively large K value. Tilt estimates based on overlapping sediments, stream gradients, and thermochronology of the Sierra Nevada plutons vary from 0° to 3° down to the southwest. Without tilt correction, the mean paleomagnetic pole for the Sierra Nevada is essentially coincident with the North American reference pole during the Cretaceous stillstand (125 Ma to 80 Ma). At 95% confidence, the apparent latitude shift is 1.1° ± 3.0° (positive northward), and the apparent rotation is negligible, 0.0° ± 4.7°. Correcting for each degree of tilt, which is limited to 3° on geologic evidence, increases the rotation anomaly 2.2° counterclockwise, while the apparent latitude shift remains unchanged.
Dynamics of the near response under natural viewing conditions with an open-view sensor

PubMed Central

Chirre, Emmanuel; Prieto, Pedro; Artal, Pablo

2015-01-01

We have studied the temporal dynamics of the near response (accommodation, convergence and pupil constriction) in healthy subjects when accommodation was performed under natural binocular and monocular viewing conditions. A binocular open-view multi-sensor based on an invisible infrared Hartmann-Shack sensor was used for non-invasive measurements of both eyes simultaneously in real time at 25Hz. Response times for each process under different conditions were measured. The accommodative responses for binocular vision were faster than for monocular conditions. When one eye was blocked, accommodation and convergence were triggered simultaneously and synchronized, despite the fact that no retinal disparity was available. We found that upon the onset of the near target, the unblocked eye rapidly changes its line of sight to fix it on the stimulus while the blocked eye moves in the same direction, producing the equivalent to a saccade, but then converges to the (blocked) target in synchrony with accommodation. This open-view instrument could be further used for additional experiments with other tasks and conditions. PMID:26504666
Automated enclosure and protection system for compact solar-tracking spectrometers

NASA Astrophysics Data System (ADS)

Heinle, Ludwig; Chen, Jia

2018-04-01

A novel automated enclosure for protecting solar-tracking atmospheric instruments was designed, constructed, and successfully tested under various weather conditions. A complete automated measurement system, consisting of a compact solar-tracking Fourier transform infrared (FTIR) spectrometer (EM27/SUN) and the enclosure, has been deployed in central Munich to monitor greenhouse gases since 2016 and withstood all critical weather conditions, including rain, storms, and snow. It provided ground-based measurements of column-averaged concentrations of CO2, CH4, O2, and H2O throughout this time.The enclosure protects the instrument from harmful environmental influences while allowing open-path measurements in sunny weather. The newly developed and patented cover, a key component of the enclosure, permits unblocked solar measurements while reliably protecting the instrument. This enables dynamic decision regarding taking measurements, and thus increases the number of data samples. This enclosure leads to a fully automated measurement system, which collects data whenever possible without any human interaction. In the long term, the enclosure will provide the foundation for a permanent greenhouse gas monitoring sensor network.
Building bridges: an interpretive phenomenological analysis of nurse educators' clinical experience using the T.R.U.S.T. Model for inclusive spiritual care.

PubMed

Scott Barss, Karen

2012-04-30

Educating nurses to provide evidence-based, non-intrusive spiritual care in today's pluralistic context is both daunting and essential. Qualitative research is needed to investigate what helps nurse educators feel more prepared to meet this challenge. This paper presents findings from an interpretive phenomenological analysis of the experience of nurse educators who used the T.R.U.S.T. Model for Inclusive Spiritual Care in their clinical teaching. The T.R.U.S.T. Model is an evidence-based, non-linear resource developed by the author and piloted in the undergraduate nursing program in which she teaches. Three themes are presented: "The T.R.U.S.T. Model as a bridge to spiritual exploration"; "blockades to the bridge"; and "unblocking the bridge". T.R.U.S.T. was found to have a positive influence on nurse educators' comfort and confidence in the teaching of spiritual care. Recommendations for maximizing the model's positive impact are provided, along with "embodied" resources to support holistic teaching and learning about spiritual care.
Metaplastic Effects of Subanesthetic Ketamine on CA1 Hippocampal Function

PubMed Central

Izumi, Yukitoshi; Zorumski, Charles F.

2014-01-01

Ketamine is a non-competitive N-methyl-D-aspartate receptor (NMDAR) antagonist of interest in neuropsychiatry. In the present studies, we examined the effects of subanesthetic, low micromolar ketamine on excitatory postsynaptic potentials (EPSPs), population spikes (PSs) and synaptic plasticity in the CA1 region of rat hippocampal slices. Ketamine acutely inhibited NMDAR-mediated synaptic responses with half-maximal effects near 10 µM. When administered for 15–30 min at 1–10 µM, ketamine had no effect on baseline dendritic AMPA receptor-mediated EPSPs, but persistently enhanced somatic EPSPs in the pyramidal cell body layer and augmented PS firing. Acute low micromolar ketamine also had no effect on the induction of long-term potentiation (LTP) but blocked long-term depression (LTD). Following 30 min administration of 1–10 µM ketamine, however, a slowly developing and persistent form of LTP inhibition was observed that took two hours following ketamine washout to become manifest. This LTP inhibition did not result from prolonged or enhanced NMDAR inhibition during drug washout. Effects of low ketamine on somatic EPSPs and LTP were not mimicked by a high ketamine concentration that completely inhibited NMDARs, and both of these effects were blocked by co-administration of low ketamine with a low concentration of the competitive NMDAR antagonist, 2-amino-5-phosphonovalerate or inhibitors of nitric oxide synthase. These results indicate that concentrations of ketamine relevant to psychotropic and psychotomimetic effects have complex metaplastic effects on hippocampal function that involve activation of unblocked NMDARs during ketamine exposure. PMID:25128848

Radiolabeling and initial biological evaluation of [18F]KBM-1 for imaging RAR-α receptors in neuroblastoma.

PubMed

Solingapuram Sai, Kiran Kumar; Das, Bhaskar C; Sattiraju, Anirudh; Almaguel, Frankis G; Craft, Suzanne; Mintz, Akiva

2017-03-15

Retinoic acid receptor alpha (RAR-α) plays a significant role in a number of diseases, including neuroblastoma. Children diagnosed with high-risk neuroblastoma are treated13-cis-retinoic acid, which reduces risk of cancer recurrence. Neuroblastoma cell death is mediated via RAR-α, and expression of RAR-α is upregulated after treatment. A molecular imaging probe that binds RAR-α will help clinicians to diagnose and stratify risk for patients with neuroblastoma, who could benefit from retinoid-based therapy. In this study, we report the radiolabeling, and initial in vivo evaluation of [ 18 F]KBM-1, a novel RAR-α agonist. The radiochemical synthesis of [ 18 F]KBM-1 was carried out through KHF 2 assisted substitution of [ 18 F] - from aryl-substituted pinacolatoesters-based retinoid precursor. In vitro cell uptake assay in human neuroblastoma cell line showed that the uptake of [ 18 F]KBM-1 was significantly inhibited by all three blocking agents (KBM-1, ATRA, BD4) at all the selected incubation times. Standard biodistribution in mice bearing neuroblastoma tumors demonstrated increased tumor uptake from 5min to 60min post radiotracer injection and the uptake ratios for target to non-target (tumor: muscle) increased 2.2-fold to 3.7-fold from 30min to 60min post injection. Tumor uptake in subset of 30min blocking group was 1.7-fold lower than unblocked. These results demonstrate the potential utility of [ 18 F]KBM-1 as a RAR-α imaging agent. Copyright © 2017 Elsevier Ltd. All rights reserved.
Modeling secondary accidents identified by traffic shock waves.

PubMed

Junhua, Wang; Boya, Liu; Lanfang, Zhang; Ragland, David R

2016-02-01

The high potential for occurrence and the negative consequences of secondary accidents make them an issue of great concern affecting freeway safety. Using accident records from a three-year period together with California interstate freeway loop data, a dynamic method for more accurate classification based on the traffic shock wave detecting method was used to identify secondary accidents. Spatio-temporal gaps between the primary and secondary accident were proven be fit via a mixture of Weibull and normal distribution. A logistic regression model was developed to investigate major factors contributing to secondary accident occurrence. Traffic shock wave speed and volume at the occurrence of a primary accident were explicitly considered in the model, as a secondary accident is defined as an accident that occurs within the spatio-temporal impact scope of the primary accident. Results show that the shock waves originating in the wake of a primary accident have a more significant impact on the likelihood of a secondary accident occurrence than the effects of traffic volume. Primary accidents with long durations can significantly increase the possibility of secondary accidents. Unsafe speed and weather are other factors contributing to secondary crash occurrence. It is strongly suggested that when police or rescue personnel arrive at the scene of an accident, they should not suddenly block, decrease, or unblock the traffic flow, but instead endeavor to control traffic in a smooth and controlled manner. Also it is important to reduce accident processing time to reduce the risk of secondary accident. Copyright © 2015 Elsevier Ltd. All rights reserved.
Ribonuclease A Homologues of the Zebrafish: Polymorphism, Crystal Structures of Two Representatives and their Evolutionary Implications

PubMed Central

Kazakou, Konstantina; Holloway, Daniel E.; Prior, Stephen H.; Subramanian, Vasanta; Acharya, K. Ravi

2008-01-01

The widespread and functionally varied members of the ribonuclease A (RNase A) superfamily provide an excellent opportunity to study evolutionary forces at work on a conserved protein scaffold. Representatives from the zebrafish are of particular interest as the evolutionary distance from non-ichthyic homologues is large. We conducted an exhaustive survey of available zebrafish DNA sequences and found significant polymorphism among its four known homologues. In an extension of previous nomenclature, the variants have been named RNases ZF-1a–c,-2a–d,-3a–e and-4. We present the first X-ray crystal structures of zebrafish ribonucleases, RNases ZF-1a and-3e at 1.35-and 1.85 Å resolution, respectively. Structure-based clustering with ten other ribonuclease structures indicates greatest similarity to mammalian angiogenins and amphibian ribonucleases, and supports the view that all present-day ribonucleases evolved from a progenitor with three disulphide bonds. In their details, the two structures are intriguing melting-pots of features present in ribonucleases from other vertebrate classes. Whereas in RNase ZF-1a the active site is obstructed by the C-terminal segment (as observed in angiogenin), in RNase ZF-3e the same region is open (as observed in more catalytically efficient homologues). The progenitor of present-day ribonucleases is more likely to have had an obstructive C terminus, and the relatively high similarity (late divergence) of RNases ZF-1 and-3 infers that the active site unblocking event has happened independently in different vertebrate lineages. PMID:18508078
Chasing the Late Jurassic APW Monster Shift in Ontario Kimberlites

NASA Astrophysics Data System (ADS)

Kent, D. V.; Muttoni, G.; Gee, J. S.; Kjarsgaard, B. A.

2012-12-01

A 30° gap was recognized in a composite APW path when global poles from predominantly igneous rocks were assembled in North American coordinates using plate reconstructions (Kent & Irving 2010 JGR). The 'monster shift' occurred between a 160-190 Ma cluster of mean poles at 75-80°N 90-110°E to a 140-145 Ma grouping centered at 60-65°N ~200°E. There are hardly any intermediate igneous poles whereas the rather divergent directions from the Late Jurassic Morrison Formation published by Steiner & Helsley (1975 GSA Bulletin) are subject to adjustments for Colorado Plateau rotation and sedimentary inclination error, neither of which are precisely known for this redbed unit sampled in Colorado. On the other hand, similar large rapid swings have been recognized in the Late Jurassic APW path for Adria (Channell et al. 2010 Paleo3), suggesting a global phenomena. In an effort to fill the data gap between ~145 and 160 Ma, we sampled accessible outcrops/subcrops of kimberlites in the Timiskaming area of Ontario, Canada, that are associated with high precision U-Pb perovskite ages (Heamon & Kjarsgaard 2000 EPSL). We report initial results from two of the intrusions: the 153.6±2.4 Ma Peddie kimberlite from outcrop and the Triple B kimberlite that was accessible by trenching and is assumed to be the same age as the nearby 153.7±1.8 Ma Seed kimberlite as delineated by aeromagnetic surveys and borings. Systematic progressive thermal demagnetization indicated in each unit a dominant characteristic component with unblocking temperatures to 575° that presumably reflect a magnetite carrier that will be checked by further rock magnetic experiments. Samples from the Peddie kimberlite had stable downward (normal polarity) magnetizations whose mean direction gives a paleopole at 73°N 184°E. In contrast, samples from the Triple B kimberlite have upward (reverse polarity) magnetizations with a well-grouped direction whose (north) paleopole is 78°N 197°E, proximal to the Peddie pole. The normal and reverse polarities suggest that sufficient time elapsed between emplacement of the Triple B and Peddie to give an opportunity to average secular variation. The combined ~154 Ma Triple B and Peddie pole encouragingly lies about halfway between igneous poles from North America nearest in age: the 169 Ma Moat volcanics and the 142 Ma Ithaca kimberlites. However, preliminary paleomagnetic results from some of the other sampled kimberlite bodies are more problematical and require further paleomagnetic and geochronological work.
Direct visualization of chemical and thermo-remanent magnetization of pseudo-single-domain magnetite grains and the implications for reliable paleomagentic signal acquisition

NASA Astrophysics Data System (ADS)

Almeida, T.; Muxworthy, A. R.; Kasama, T.; Williams, W.; Kovács, A.; Dunin-Borkowski, R.; Hansen, T. W.

2015-12-01

In order to reliably interpret paleomagnetic measurements, the mechanisms of chemical remanent magnetization (CRM) and thermoremanent magnetization (TRM) must be fully understood. Currently, most models of CRM and TRM processes only exist for the smallest, uniformly magnetized grains, termed single domain (SD). However, the magnetic signal from rocks is often dominated by slightly larger grains containing non-uniform magnetization states, termed pseudo-SD (PSD) grains. Magnetite (Fe3O4) is the most magnetic naturally occurring mineral on Earth, carrying the dominant magnetic signature in rocks and providing a critical tool in paleomagnetism. The oxidation of Fe3O4 to other iron oxides, such as maghemite (γ-Fe2O3) and hematite (α-Fe2O3), is of particular interest as it influences the preservation of remanence of the Earth's magnetic field by Fe3O4. Further, TRM in Fe3O4 grains is acquired in the direction of the ambient geomagnetic field as they cool below their Curie temperature (TC) of ~ 580 ˚C. The latest transmission electron microscopy (TEM) techniques like electron holography and environmental TEM (ETEM) allows for the imaging of magnetization in nano-scale minerals during in situ heating under vacuum and controlled atmospheres. In the present study, synthetic Fe3O4 particles in the PSD size range (< 200 nm) were heated in situ in an ETEM under an O2 atmosphere. Close examination of Fe3O4 particles after in situ heating revealed surface degradation, whilst electron energy-loss spectroscopy confirmed their oxidation. The effect of CRM was visualized using electron holography, in the form of reconstructed magnetic induction maps, where the oxidized grains exhibited a loss of overall remanence and change in remanent direction. The thermomagnetic behavior of Fe3O4 particles in the PSD size range is also investigated using off-axis electron holography. Magnetic induction maps, which are recorded during in situ heating up to above the TC, reveal the PSD nature of several Fe3O4 grains by visualizing their vortex domain states. The vortex states in small Fe3O4 grains (Fig. 1a & b) are shown to rotate or collapse into a single-domain state close to its unblocking temperature (Fig. 1c), rather than remaining thermally stable as seen in the vortex states of larger Fe3O4 grains.
Absolute Paleointensity Techniques: Developments in the Last 10 Years (Invited)

NASA Astrophysics Data System (ADS)

Bowles, J. A.; Brown, M. C.

2009-12-01

The ability to determine variations in absolute intensity of the Earth’s paleomagnetic field has greatly enhanced our understanding of geodynamo processes, including secular variation and field reversals. Igneous rocks and baked clay artifacts that carry a thermal remanence (TRM) have allowed us to study field variations over timescales ranging from decades to billions of years. All absolute paleointensity techniques are fundamentally based on repeating the natural process by which the sample acquired its magnetization, i.e. a laboratory TRM is acquired in a controlled field, and the ratio of the natural TRM to that acquired in the laboratory is directly proportional to the ancient field. Techniques for recovering paleointensity have evolved since the 1930s from relatively unsophisticated (but revolutionary for their time) single step remagnetizations to the various complicated, multi-step procedures in use today. These procedures can be broadly grouped into two categories: 1) “Thellier-type” experiments that step-wise heat samples at a series of temperatures up to the maximum unblocking temperature of the sample, progressively removing the natural remanence (NRM) and acquiring a laboratory-induced TRM; and 2) “Shaw-type” experiments that combine alternating field demagnetization of the NRM and laboratory TRM with a single heating to a temperature above the sample’s Curie temperature, acquiring a total TRM in one step. Many modifications to these techniques have been developed over the years with the goal of identifying and/or accommodating non-ideal behavior, such as alteration and multi-domain (MD) remanence, which may lead to inaccurate paleofield estimates. From a technological standpoint, perhaps the most significant development in the last decade is the use of microwave (de)magnetization in both Thellier-type and Shaw-type experiments. By using microwaves to directly generate spin waves within the magnetic grains (rather than using phonons generated by heating, which then exchange energy with the magnetic system), a TRM can be acquired with minimal heating of the bulk sample, thus potentially minimizing sample alteration. The theory of TRM acquisition is best developed for single-domain (SD) grains, and most paleointensity techniques are predicated on the assumption that the remanence is carried predominantly by SD material. Because the vast majority of geological materials are characterized by a larger magnetic grain size, efforts to expand paleointensity studies over the past decade have focused on developing TRM theories and paleointensity methods for pseudo-single-domain (PSD) and MD samples. Other workers have been exploring the potential of SD materials that were not traditionally used in paleointensity studies, such as ash flow tuffs, submarine basaltic glass, and single silicate crystals with magnetite inclusions. The latter has the potential to shed light on early Earth processes, given that the fine-grained inclusions may be resistant to alteration over long time scales. We will review the major paleointensity techniques in use today, with special attention paid to the advantages and disadvantages of each. Techniques will be illustrated with examples highlighting new paleointensity applications to geologic processes at a variety of timescales.
Radiolabeling and in vitro and in vivo characterization of [18F]FB-[R(8,15,21), L17]-VIP as a PET imaging agent for tumor overexpressed VIP receptors.

PubMed

Cheng, Dengfeng; Yin, Duanzhi; Li, Gucai; Wang, Mingwei; Li, Shiqiang; Zheng, Mingqiang; Cai, Hancheng; Wang, Yongxian

2006-12-01

In an effort to develop a peptide-based radiopharmaceutical for the detection of tumors overexpressed vasoactive intestinal peptide receptors with positron emission tomography, we have prepared a novel [R(8,15,21), L17]-VIP peptide for 18F-labeling. This peptide inhibited 125I-VIP binding to rats lung membranes with high affinity [half-maximal inhibitory concentrations (IC50) of 0.12 nm]. Additionally, [R(8,15,21), L17]-VIP showed higher stability than native vasoactive intestinal peptide in vivo of mice. With N-succinimidyl 4-[18F] fluorobenzoate as labeling prosthetic group, [18F]FB-[R(8,15,21), L17]-VIP was obtained in >99% radiochemical purity within 100 min in decay-for-corrected radiochemical yield of 33.6 +/- 3% (n = 5) and a specific radioactivity 255 GBq/micromol at the end of synthesis. Stability of [18F]FB-[R(8,15,21), L17]-VIP in vitro and in vivo were investigated. Biodistribution of this trace was carried out in mice with induced C26 colorectal tumor. Fast clearance of [18F]FB-[R(8,15,21), L17]-VIP from non-target tissues and specific uptakes by tumors realized higher tumor-to-muscle ratio (3.55) and tumor-to-blood ratio (2.37) 60 min postinjection. Clear difference was observed between the blocking and unblocking experiments in biodistribution and whole body radioautography. [18F]FB-[R(8,15,21), L17]-VIP has demonstrated its potential for diagnosing tumors overexpressed vasoactive intestinal peptide receptors both in vitro and in vivo.
Development of a novel CsA-PLGA drug delivery system based on a glaucoma drainage device for the prevention of postoperative fibrosis.

PubMed

Dai, Zhaoxing; Yu, Xiaobo; Hong, Jiaxu; Liu, Xi; Sun, Jianguo; Sun, Xinghuai

2016-09-01

The formation of a scar after glaucoma surgery often leads to unsuccessful control of intraocular pressure, and should be prevented by using a variety of methods. We designed and developed a novel drug delivery system (DDS) comprising cyclosporine A (CsA) and poly(lactic-co-glycolic acid) (PLGA) based on a glaucoma drainage device (GDD) that can continuously release CsA to prevent postoperative fibrosis following glaucoma surgery. The CsA@PLGA@GDD DDS was observed by field emission scanning electron microscopy and revealed an asymmetric pore structure. Thermogravimetric analysis was performed to measure the weight loss and evaluate the thermal stability of the CsA@PLGA@GDD DDS. The in vitro drug release profile of the DDS was studied using high performance liquid chromatography, which confirmed that the DDS released CsA at a stable rate and maintained adequate CsA concentrations for a relatively long time. The biocompatibility of the DDS and the inhibitory effects on the postoperative fibrosis were investigated in vitro using rabbit Tenon's fibroblasts. The in vivo safety and efficacy of the DDS were examined by implanting the DDS into Tenon's capsules in New Zealand rabbits. Bleb morphology, intraocular pressure, anterior chamber reactions, and anterior chamber angiography were studied at a series of set times. The DDS kept the filtration pathway unblocked for a longer time compared with the control GDD. The results indicate that the CsA@PLGA@GDD DDS represents a safe and effective strategy for preventing scar formation after glaucoma surgery. Copyright © 2016 Elsevier B.V. All rights reserved.
Longitudinal Analysis of Vaginal Microbiome Dynamics in Women with Recurrent Bacterial Vaginosis: Recognition of the Conversion Process

PubMed Central

Lambert, Janet A.; John, Susan; Sobel, Jack D.; Akins, Robert A.

2013-01-01

Bacterial vaginosis (BV) affects ∼30% of women of reproductive age, has a high rate of recurrence, and is associated with miscarriage, preterm birth, and increased risk of acquiring other sexually transmitted infections, including HIV-1. Little is known of the daily changes in the vaginal bacterial composition as it progresses from treatment to recurrence, or whether any of these might be useful in its prediction or an understanding of its causes. We used phylogenetic branch-inclusive quantitative PCR (PB-qPCR) and Lactobacillus blocked/unblocked qPCR (Lb-qPCR) to characterize longitudinal changes in the vaginal microbiota in sequential vaginal self-swabs from five women with recurrent BV, from diagnosis through remission to recurrence. Both patients with acute BV samples dominated by G. vaginalis recurred during the study with similar profiles, whereas the three patients with acute BV samples dominated by other anaerobes did not recur or recurred to an intermediate Nugent score. L. iners dominated remission phases, with intermittent days of abnormal microbial profiles typically associated with menses. The exception was a newly discovered phenomenon, a sustained period of abnormal profiles, termed conversion, which preceded symptomatic acute BV. Species known to have antagonistic activity towards Lactobacillus were detected in pre-conversion samples, possibly contributing to the decline in Lactobacillus. Lb-qPCR scores define two categories of response in the initial post-treatment visit samples; scores <5 may correspond with poor response to treatment or rapid recurrence, whereas scores >8 may predict delayed or no recurrence. Amsel criteria or Nugent scores did not have this potential predictive capability. Larger studies are warranted to evaluate the prognostic potential of detecting conversion and poor Lb-qPCR scores at the post-treatment visit of recurrent BV patients. PMID:24376552
Direct block of native and cloned (Kir2.1) inward rectifier K+ channels by chloroethylclonidine

PubMed Central

Barrett-Jolley, R; Dart, C; Standen, N B

1999-01-01

We have investigated the inhibition of inwardly rectifying potassium channels by the α-adrenergic agonist/antagonist chloroethylclonidine (CEC). We used two preparations; two-electrode voltage-clamp of rat isolated flexor digitorum brevis muscle and whole-cell patch-clamp of cell lines transfected with Kir2.1 (IRK1).In skeletal muscle and at a membrane potential of −50 mV, chloroethylclonidine (CEC), an agonist at α2-adrenergic receptors and an antagonist at α1x-receptors, was found to inhibit the inward rectifier current with a Ki of 30 μM.The inhibition of skeletal muscle inward rectifier current by CEC was not mimicked by clonidine, adrenaline or noradrenaline and was not sensitive to high concentrations of α1-(prazosin) or α2-(rauwolscine) antagonists.The degree of current inhibition by CEC was found to vary with the membrane potential (approximately 70% block at −50 mV c.f. ∼10% block at −190 mV). The kinetics of this voltage dependence were further investigated using recombinant inward rectifier K+ channels (Kir2.1) expressed in the MEL cell line. Using a two pulse protocol, we calculated the time constant for block to be ∼8 s at 0 mV, and the rate of unblock was described by the relationship τ=exp((Vm+149)/22) s.This block was effective when CEC was applied to either the inside or the outside of patch clamped cells, but ineffective when a polyamine binding site (aspartate 172) was mutated to asparagine.The data suggest that the clonidine-like imidazoline compound, CEC, inhibits inward rectifier K+ channels independently of α-receptors by directly blocking the channel pore, possibly at an intracellular polyamine binding site. PMID:10516659
Paleomagnetism and alteration of lower Paleozoic rocks and Precambrian basement in the SHADS No. 4 drill core, Oklahoma

NASA Astrophysics Data System (ADS)

Evans, S. C.; Hamilton, M.; Hardwick, J.; Terrell, C.; Elmore, R. D.

2017-12-01

The chacterization of the lower Paleozoic sedimentary rock and the underlying Precambrian basement in northern Oklahoma is currently the subject of research to better understand induced seismicity in Oklahoma. We are investigating approximately 140 meters of igneous basement and over 300 meters of Ordovician Arbuckle Group carbonates and underlying sandstone in the Amoco SHADS No. 4 drill core from Rogers Co., Oklahoma, to better understand the nature, origin, and timing of fluid alteration and the relationship between fluid flow in the Arbuckle Group and the basement. Preliminary attempts to orient the core using the viscous remanent magnetization (VRM) method were unsuccessful, probably due to a steep drilling-induced component. The dolomitized Arbuckle Group contains a characteristic remanent magnetization (ChRM) with shallow inclinations (-5°) and variable declinations that, based on unblocking temperatures, is interpreted to reside in magnetite. This ChRM is interpreted as a chemical remanent magnetization (CRM) acquired in the Permian based on the shallow inclinations. The CRM could be related to hydrothermal fluids which migrated into the rocks in the late Paleozoic, as other studies in northern Oklahoma have reported. The Arbuckle Group dolomites are porous and extensively altered and consist of several generations of dolomite, including baroque dolomite. The basement rock is andesitic to trachytic ignimbrite that exhibits extensive alteration. There are many near-vertical fractures mineralized with epidote that are cross cut by calcite-filled fractures. Anisotropy of magnetic susceptibility (AMS) measurements indicate an oblate fabric in the top of the basement and the overlying sandstones. At greater depths, the AMS is variable and may include both alteration and primary fabrics. Demagnetization of the basement rocks is in the initial stages. We are currently investigating if and how far the alteration in the Arbuckle Group extended into the basement. The results suggest basement and sedimentary rock in the core were altered by multiple fluids, and the pervasive fracturing in the igneous section could provide conduits for fluids to get from the porous Arbuckle Group into the basement.
Tectonic deformation around the eastern Himalayan syntaxis: constraints from the Cretaceous palaeomagnetic data of the Shan-Thai Block

NASA Astrophysics Data System (ADS)

Tanaka, Kenji; Mu, Chuanlong; Sato, Ken; Takemoto, Kazuhiro; Miura, Daisuke; Liu, Yuyan; Zaman, Haider; Yang, Zhenyu; Yokoyama, Masahiko; Iwamoto, Hisanori; Uno, Koji; Otofuji, Yo-ichiro

2008-11-01

Lower to Middle Cretaceous red sandstones were sampled at four localities in the Lanpin-Simao fold belt of the Shan-Thai Block to describe its regional deformational features. Most of the samples revealed a characteristic remanent magnetization with unblocking temperatures around 680 °C. Primary natures of magnetization are ascertained through positive fold test. A tilt-corrected formation-mean direction for the Jingdong (24.5°N, 100.8°E) locality, which is located at a distance of 25 km from the Ailaoshan-Red River Fault, revealed northerly declination with steep inclination (Dec./Inc. = 8.3°/48.8°, α95 = 7.7°, N = 13). However, mean directions obtained from the Zhengyuan (24.0°N, 101.1°E), West Zhengyuan (24.0°N, 101.1°E) and South Mengla (21.4°N, 101.6°E) localities indicate an easterly deflection in declination; such as Dec./Inc. = 61.8°/46.1°, α95 = 8.1° (N = 7), Dec./Inc. = 324.2°/-49.4°, α95 = 6.4° (N = 4) and Dec./Inc. = 51.2°/46.4°, α95 = 5.6° (N = 13), respectively. The palaeomagnetic directions obtained from these four localities are incorporated into a palaeomagnetic database for the Shan-Thai Block. When combined with geological, geochronological and GPS data, the processes of deformation in the Shan-Thai Block is described as follows: Subsequent to its rigid block clockwise rotation of about 20° in the early stage of India-Asia collision, the Shan-Thai Block experienced a coherent but southward displacement along the Red River Fault prior to 32 Ma. This block was then subjected to a north-south compressive stresses during the 32-27 Ma period, which played a key role in shaping the structure of Chongshan-Lancang-Chiang Mai Belt. Following this some local clockwise rotational motion has occurred during the Pliocene-Quaternary time in central part of the Shan-Thai Block as a result of internal block movements along the reactivated network of faults.
Paleomagnetism of the Oman Ophiolite: New Results from Oman Drilling Project Cores

NASA Astrophysics Data System (ADS)

Horst, A. J.; Till, J. L.; Koornneef, L.; Usui, Y.; Kim, H.; Morris, A.

2017-12-01

The Oman Drilling Project drilled holes at four sites in a transect through the southern massifs of the Samail ophiolite, and recovered 1500 m of igneous and metamorphic rocks. We focus on three sites from the oceanic crustal section including lower layered gabbros (GT1A), the mid-crustal layered to foliated gabbro transition (GT2A), and the shallower transition from sheeted dikes to varitextured gabbros (GT3A). Detailed core descriptions, analyses, and paleomagnetic measurements, were made on D/V Chikyu from July to September 2017 to utilize the core laboratory facilities similar to IODP expeditions. Shipboard measurements included anisotropy of magnetic susceptibility (AMS) and alternating field and thermal demagnetization of 597 discrete samples. Sample demagnetization behavior is varied from each of the cores, with some revealing multiple components of magnetization, and others yielding nearly univectorial data. The interpretation of results from the lower crustal cores is complicated by the pervasive presence of secondary magnetite. In almost all samples, a stable component was resolved (interpreted as a characteristic remanent magnetization) after removal of a lower-coercivity or lower unblocking-temperature component. The inclinations of the stable components in the core reference frame are very consistent in Hole GT1A. However, a transition from negative to positive inclinations in GT2A suggests some structural complexity, possibly as a result of intense late faulting activity. Both abrupt and gradual transitions between multiple zones of negative and positive inclinations occur in Hole GT3A. Interpretation and direct comparison of remanence between drill sites is difficult as recovered core pieces currently remain azimuthally unoriented, and GT2A was drilled at a plunge of 60°, whereas GT1A and GT3A were both drilled vertically. Work is ongoing to use borehole imagery to reorient the core pieces and paleomagnetic data into a geographic in situ reference frame. We will present an overview of preliminary AMS and remanence data that will be used in the future to 1) document deformational histories, 2) characterize magmatic flow directions at different structural levels, and 3) identify the magnetic mineralogy of remanence carriers throughout the oceanic crustal section.
Resurgent current of voltage-gated Na+ channels

PubMed Central

Lewis, Amanda H; Raman, Indira M

2014-01-01

Resurgent Na+ current results from a distinctive form of Na+ channel gating, originally identified in cerebellar Purkinje neurons. In these neurons, the tetrodotoxin-sensitive voltage-gated Na+ channels responsible for action potential firing have specialized mechanisms that reduce the likelihood that they accumulate in fast inactivated states, thereby shortening refractory periods and permitting rapid, repetitive, and/or burst firing. Under voltage clamp, step depolarizations evoke transient Na+ currents that rapidly activate and quickly decay, and step repolarizations elicit slower channel reopening, or a ‘resurgent’ current. The generation of resurgent current depends on a factor in the Na+ channel complex, probably a subunit such as NaVβ4 (Scn4b), which blocks open Na+ channels at positive voltages, competing with the fast inactivation gate, and unblocks at negative voltages, permitting recovery from an open channel block along with a flow of current. Following its initial discovery, resurgent Na+ current has been found in nearly 20 types of neurons. Emerging research suggests that resurgent current is preferentially increased in a variety of clinical conditions associated with altered cellular excitability. Here we review the biophysical, molecular and structural mechanisms of resurgent current and their relation to the normal functions of excitable cells as well as pathophysiology. PMID:25172941
Study on turbulent flow and heat transfer performance of tubes with internal fins in EGR cooler

NASA Astrophysics Data System (ADS)

Liu, Lin; Ling, Xiang; Peng, Hao

2015-07-01

In this paper, flow and heat transfer performances of the tubes with internal longitudinal fins in Exhaust Gas Recirculation (EGR ) cooler were investigated by three-dimension computation and experiment . Each test tube was a single-pipe structure, without inner tube. Three-dimension computation was performed to determine the thermal characteristics difference between the two kinds of tubes, that is, the tube with an inner solid staff as a blocked structure and the tube without the blocked structure. The effects of fin width and fin height on heat transfer and flow are examined. For proving the validity of numerical method, the calculated results were compared with corresponding experimental data. The tube-side friction factor and heat transfer coefficient were examined. As a result, the maximum deviations between the numerical results and the experimental data are approximately 5.4 % for friction factor and 8.6 % for heat transfer coefficient, respectively. It is found that two types of internally finned tubes enhance significantly heat transfer. The heat transfer of the tube with blocked structure is better, while the pressure drop of the tube without blocked structure is lower. The comprehensive performance of the unblocked tube is better to applied in EGR cooler.
An equilibrium-point model for fast, single-joint movement: II. Similarity of single-joint isometric and isotonic descending commands.

PubMed

Latash, M L; Gottlieb, G L

1991-09-01

The model for isotonic movements introduced in the preceding article in this issue is used to account for isometric contractions. Isotonic movements and isometric contractions are analyzed as consequences of one motor program acting under different peripheral conditions. Differences in isotonic and isometric EMG patterns are analyzed theoretically. Computer simulation of the EMG patterns was performed both with and without the inclusion of possible effects of reciprocal inhibition. A series of experiments was performed to test the model. The subjects made fast isotonic movements that were unexpectedly blocked at the very beginning in some of the trials. The observed differences in the EMG patterns between blocked and unblocked trials corresponded to the model's predictions. The results suggest that these differences are due to the action of a tonic stretch reflex rather than to preprogrammed reactions. The experimental and simulation findings, and also the data from the literature, are discussed in the framework of the model and the dual-strategy hypothesis. They support the hypothesis that the motor control system uses one of a few standardized subprograms, specifying a small number of parameters to match a specific task.
Role of AMPA and NMDA receptors and back-propagating action potentials in spike timing-dependent plasticity.

PubMed

Fuenzalida, Marco; Fernández de Sevilla, David; Couve, Alejandro; Buño, Washington

2010-01-01

The cellular mechanisms that mediate spike timing-dependent plasticity (STDP) are largely unknown. We studied in vitro in CA1 pyramidal neurons the contribution of AMPA and N-methyl-d-aspartate (NMDA) components of Schaffer collateral (SC) excitatory postsynaptic potentials (EPSPs; EPSP(AMPA) and EPSP(NMDA)) and of the back-propagating action potential (BAP) to the long-term potentiation (LTP) induced by a STDP protocol that consisted in pairing an EPSP and a BAP. Transient blockade of EPSP(AMPA) with 7-nitro-2,3-dioxo-1,4-dihydroquinoxaline-6-carbonitrile (CNQX) during the STDP protocol prevented LTP. Contrastingly LTP was induced under transient inhibition of EPSP(AMPA) by combining SC stimulation, an imposed EPSP(AMPA)-like depolarization, and BAP or by coupling the EPSP(NMDA) evoked under sustained depolarization (approximately -40 mV) and BAP. In Mg(2+)-free solution EPSP(NMDA) and BAP also produced LTP. Suppression of EPSP(NMDA) or BAP always prevented LTP. Thus activation of NMDA receptors and BAPs are needed but not sufficient because AMPA receptor activation is also obligatory for STDP. However, a transient depolarization of another origin that unblocks NMDA receptors and a BAP may also trigger LTP.
Scheduling for anesthesia at geographic locations remote from the operating room.

PubMed

Dexter, Franklin; Wachtel, Ruth E

2014-08-01

Providing general anesthesia at locations away from the operating room, called remote locations, poses many medical and scheduling challenges. This review discusses how to schedule procedures at remote locations to maximize anesthesia productivity (see Video, Supplemental Digital Content 1). Anesthesia labour productivity can be maximized by assigning one or more 8-h or 10-h periods of allocated time every 2 weeks dedicated specifically to each remote specialty that has enough cases to fill those periods. Remote specialties can then schedule their cases themselves into their own allocated time. Periods of allocated time (called open, unblocked or first come first served time) can be used by remote locations that do not have their own allocated time. Unless cases are scheduled sequentially into allocated time, there will be substantial extra underutilized time (time during which procedures are not being performed and personnel sit idle even though staffing has been planned) and a concomitant reduction in percent productivity. Allocated time should be calculated on the basis of usage. Remote locations with sufficient hours of cases should be allocated time reserved especially for them in which to schedule their cases, with a maximum waiting time of 2 weeks, to achieve an average wait of 1 week.
Iodine-131-labeled diphosphonates for palliative treatment of bone metastases: II. Preliminary clinical results with iodine-131 BDP3.

PubMed

Eisenhut, M; Berberich, R; Kimmig, B; Oberhausen, E

1986-08-01

The kinetics, dosimetry, and response of iodine-131 alpha-amino-(4-hydroxybenzylidene)-diphosphonate ([131I]BDP3) treatment were investigated with patients who had pain symptoms from bone metastases of various primary carcinoma. The blood clearance of [131I]BDP3 was rapid. More than 90% disappeared from the blood pool at 2 hr after injection. The excretion of the activity occurred solely through the kidneys and mean total-body retention at 48 hr was 48.6%. The urinary activity showed a metabolite which must be formed by an in vivo cleavage reaction of a phosphorus-carbon bond. The uptake of in vivo cleaved [131I]iodide in the unblocked thyroid was approximately 0.5%. The effective half-life of [131I]BDP3 in metastatic bone (median 182 hr; range 177-205 hr) proved to be longer than in unaffected areas (145 hr; 140-165 hr). Palliative therapies were performed with 18 patients. They received doses ranging between 6 and 48 mCi [131I]BDP3. The response was 44% complete pain relief, 6% substantial pain relief, 22% minimal improvement, and 28% no change. The duration of response ranged between 1 and 8 wk.
500 C Electronic Packaging and Dielectric Materials for High Temperature Applications

NASA Technical Reports Server (NTRS)

Chen, Liang-yu; Neudeck, Philip G.; Spry, David J.; Beheim, Glenn M.; Hunter, Gary W.

2016-01-01

High-temperature environment operable sensors and electronics are required for exploring the inner solar planets and distributed control of next generation aeronautical engines. Various silicon carbide (SiC) high temperature sensors, actuators, and electronics have been demonstrated at and above 500C. A compatible packaging system is essential for long-term testing and application of high temperature electronics and sensors. High temperature passive components are also necessary for high temperature electronic systems. This talk will discuss ceramic packaging systems developed for high temperature electronics, and related testing results of SiC circuits at 500C and silicon-on-insulator (SOI) integrated circuits at temperatures beyond commercial limit facilitated by these high temperature packaging technologies. Dielectric materials for high temperature multilayers capacitors will also be discussed. High-temperature environment operable sensors and electronics are required for probing the inner solar planets and distributed control of next generation aeronautical engines. Various silicon carbide (SiC) high temperature sensors, actuators, and electronics have been demonstrated at and above 500C. A compatible packaging system is essential for long-term testing and eventual applications of high temperature electronics and sensors. High temperature passive components are also necessary for high temperature electronic systems. This talk will discuss ceramic packaging systems developed for high electronics and related testing results of SiC circuits at 500C and silicon-on-insulator (SOI) integrated circuits at temperatures beyond commercial limit facilitated by high temperature packaging technologies. Dielectric materials for high temperature multilayers capacitors will also be discussed.

A Microscale View of Mixing and Overturning Across the Antarctic Circumpolar Current

NASA Astrophysics Data System (ADS)

Naveira Garabato, A.; Polzin, K. L.; Ferrari, R. M.; Zika, J. D.; Forryan, A.

2014-12-01

The meridional overturning circulation and stratication of the global ocean are shaped critically by processes in the Southern Ocean. The zonally unblocked nature of the Antarctic Circumpolar Current (ACC) confers the region with a set of special dynamics that ultimately results in the focussing therein of large vertical exchanges between layers spanning the global ocean pycnocline. These vertical exchanges are thought to be mediated by oceanic turbulent motions (associated with mesoscale eddies and small-scale turbulence), yet the vastness of the Southern Ocean and the sparse and intermittent nature of turbulent processes make their relative roles and large-scale impacts extremely difficult to assess.Here, we address the problem from a new angle, and use measurements of the centimetre-scale signatures of mesoscale eddies and small-scale turbulence obtained during the DIMES experiment to determine the contributions of those processes to sustaining large-scale meridional overturning across the ACC. We find that mesoscale eddies and small-scale turbulence play complementary roles in forcing a meridional circulation of O(1 mm / s) across the Southern Ocean, and that their roles are underpinned by distinct and abrupt variations in the rates at which they mix water parcels. The implications for our understanding of the Southern Ocean circulation's sensitivity to climatic change will be discussed.
Progress in improving provincial plans for nutrition through targeted technical assistance and local advocacy in Vietnam

PubMed Central

Harris, Jody; Nguyen, Phuong H.; To, Quyen; Frongillo, Edward A.; Menon, Purnima

2016-01-01

Vietnam has been decentralizing nutrition planning to provinces, which could help with local relevance and accountability. Assessment in 2009 found a continuing top-down approach, limited human capacity, and difficulty in integrating multiple sectors. Alive and Thrive (A&T) provided targeted assistance and capacity-building for 15 provincial plans for nutrition (PPNs). We aimed to (i) assess PPN content and quality improvements 2009–2014, and (ii) explain processes through which change occurred. Data consisted of interview-based assessments of provincial planning processes, annual PPN assessments, and tracking of A&T involvement. At endline, some provinces produced higher quality plans. Local planning skills improved, but capacity remained insufficient. Awareness of and support for nutrition improved, but some policy and legal environments were contradictory. Objectives were clearer, but use of data for planning remained inconsistent. Provinces became more proactive and creative, but remained constrained by slow approval processes and insufficient funding. Targeted assistance and local advocacy can improve decentralized planning, with success dependent on policy and programming contexts and ability to overcome constraints around capacity, investment, data use and remnants of centralized planning. We recommend strong engagement with planners at the national level to understand how to unblock major constraints; solutions must take into consideration the particular political, financial and administrative context. PMID:27198978
The Research and Application of Information Platform About Community Support Intervention for Patients with Alcohol Dependence.

PubMed

Yang, Liqun

2016-01-01

Through the establishment of electronic health records, health education and measures such as regional information sharing platform, we explored the management of patients with alcohol dependence living in communities and established a medical information resource sharing model between mental hospital-community to strengthen the supportive intervention management of patients with alcohol dependence, improve the effect of intervention and reduce the rate of compound drink. To design the questionnaire of health state for patients with alcohol dependence. After data collection. We should establish electronic health records and community support intervention, make medical health card with terminal configuration card reader in both mental hospitals and community, develop information platform, establish a variety of supporting interventions and the service function modules, unblock information sharing between hospitals and community to make full use of the platform to carry out health education and health intervention management. The effectives of community supportive intervention are improved, rehabilitation rate of patients is reduced greatly, bad ways of life behavior are better. Establishing electronic health records is an important mean of community supportive interventions which is good for Real-time, dynamic management and promoting self-management skills making the dream of medical information resource between hospital-community sharing come true.
Optimization of Treatment Geometry to Reduce Normal Brain Dose in Radiosurgery of Multiple Brain Metastases with Single-Isocenter Volumetric Modulated Arc Therapy.

PubMed

Wu, Qixue; Snyder, Karen Chin; Liu, Chang; Huang, Yimei; Zhao, Bo; Chetty, Indrin J; Wen, Ning

2016-09-30

Treatment of patients with multiple brain metastases using a single-isocenter volumetric modulated arc therapy (VMAT) has been shown to decrease treatment time with the tradeoff of larger low dose to the normal brain tissue. We have developed an efficient Projection Summing Optimization Algorithm to optimize the treatment geometry in order to reduce dose to normal brain tissue for radiosurgery of multiple metastases with single-isocenter VMAT. The algorithm: (a) measures coordinates of outer boundary points of each lesion to be treated using the Eclipse Scripting Application Programming Interface, (b) determines the rotations of couch, collimator, and gantry using three matrices about the cardinal axes, (c) projects the outer boundary points of the lesion on to Beam Eye View projection plane, (d) optimizes couch and collimator angles by selecting the least total unblocked area for each specific treatment arc, and (e) generates a treatment plan with the optimized angles. The results showed significant reduction in the mean dose and low dose volume to normal brain, while maintaining the similar treatment plan qualities on the thirteen patients treated previously. The algorithm has the flexibility with regard to the beam arrangements and can be integrated in the treatment planning system for clinical application directly.
Intact proprioception and control of labour pain during epidural analgesia.

PubMed

Abrahams, M; Higgins, P; Whyte, P; Breen, P; Muttu, S; Gardiner, J

1999-01-01

Accurate proprioception is critical while walking, yet an ambulatory epidural regimen that provides adequate analgesia for labour while simultaneously preserving proprioceptive input has not been described. Sixty primigravidae in established labour received bupivacaine 15 mg (15 ml of 0.1% w/v) and fentanyl 100 micrograms through a lumbar epidural catheter. Clinical assessment of dorsal column sensory function included: vibration sense, distal proprioception and the Romberg test, and were all performed before catheter insertion and 30 min after the study bolus. Sensory modalities were also tested compared to an unblocked dermatome. Pain was scored on a 0-10 cm visual analogue scale (VAS) before and 30 min after induction. Intensity of the motor block was tested using a modified Bromage score (grade 1-6). The study bolus provided reliable analgesia with 43 parturients attaining a VAS pain score of zero. Mean duration of analgesia was 67.5 min (SD 22.85). All parturients retained the ability to perform a partial knee bend while standing (grade 6). No mothers exhibited impaired distal proprioception, altered vibration sense or a positive Romberg sign. This study confirms that the addition of lumbar epidural fentanyl 100 micrograms to 15 mg of epidural bupivacaine provides good control of labour pain with no motor block and establishes that this combination preserves dorsal column sensory function.
FEM Modeling of the Relationship between the High-Temperature Hardness and High-Temperature, Quasi-Static Compression Experiment.

PubMed

Zhang, Tao; Jiang, Feng; Yan, Lan; Xu, Xipeng

2017-12-26

The high-temperature hardness test has a wide range of applications, but lacks test standards. The purpose of this study is to develop a finite element method (FEM) model of the relationship between the high-temperature hardness and high-temperature, quasi-static compression experiment, which is a mature test technology with test standards. A high-temperature, quasi-static compression test and a high-temperature hardness test were carried out. The relationship between the high-temperature, quasi-static compression test results and the high-temperature hardness test results was built by the development of a high-temperature indentation finite element (FE) simulation. The simulated and experimental results of high-temperature hardness have been compared, verifying the accuracy of the high-temperature indentation FE simulation.The simulated results show that the high temperature hardness basically does not change with the change of load when the pile-up of material during indentation is ignored. The simulated and experimental results show that the decrease in hardness and thermal softening are consistent. The strain and stress of indentation were analyzed from the simulated contour. It was found that the strain increases with the increase of the test temperature, and the stress decreases with the increase of the test temperature.
FEM Modeling of the Relationship between the High-Temperature Hardness and High-Temperature, Quasi-Static Compression Experiment

PubMed Central

Zhang, Tao; Jiang, Feng; Yan, Lan; Xu, Xipeng

2017-01-01

The high-temperature hardness test has a wide range of applications, but lacks test standards. The purpose of this study is to develop a finite element method (FEM) model of the relationship between the high-temperature hardness and high-temperature, quasi-static compression experiment, which is a mature test technology with test standards. A high-temperature, quasi-static compression test and a high-temperature hardness test were carried out. The relationship between the high-temperature, quasi-static compression test results and the high-temperature hardness test results was built by the development of a high-temperature indentation finite element (FE) simulation. The simulated and experimental results of high-temperature hardness have been compared, verifying the accuracy of the high-temperature indentation FE simulation.The simulated results show that the high temperature hardness basically does not change with the change of load when the pile-up of material during indentation is ignored. The simulated and experimental results show that the decrease in hardness and thermal softening are consistent. The strain and stress of indentation were analyzed from the simulated contour. It was found that the strain increases with the increase of the test temperature, and the stress decreases with the increase of the test temperature. PMID:29278398
DOE Office of Scientific and Technical Information (OSTI.GOV)

Song, Bo; Nelson, Kevin; Lipinski, Ronald J.

Iridium alloys have superior strength and ductility at elevated temperatures, making them useful as structural materials for certain high-temperature applications. However, experimental data on their high-temperature high-strain-rate performance are needed for understanding high-speed impacts in severe elevated-temperature environments. Kolsky bars (also called split Hopkinson bars) have been extensively employed for high-strain-rate characterization of materials at room temperature, but it has been challenging to adapt them for the measurement of dynamic properties at high temperatures. Current high-temperature Kolsky compression bar techniques are not capable of obtaining satisfactory high-temperature high-strain-rate stress-strain response of thin iridium specimens investigated in this study. We analyzedmore » the difficulties encountered in high-temperature Kolsky compression bar testing of thin iridium alloy specimens. Appropriate modifications were made to the current high-temperature Kolsky compression bar technique to obtain reliable compressive stress-strain response of an iridium alloy at high strain rates (300 – 10000 s -1) and temperatures (750°C and 1030°C). Uncertainties in such high-temperature high-strain-rate experiments on thin iridium specimens were also analyzed. The compressive stress-strain response of the iridium alloy showed significant sensitivity to strain rate and temperature.« less
Reliability Evaluation of Low Power Schottky Clamped Microcircuits.

DTIC Science & Technology

1980-02-01

Temperature 52 15. 54LS191: ICC Versus Temperature 53 16. 54LS181: ICC Versus Temperature 54 17. High Temperature ...Response, Vendor A, 54LS181 56 18. High Temperature Response, Vendor B, 54LS181 57 19. High Temperature Response, Vendor A, 54LS191 58 20. High ... Temperature Response, Vendor B, 54LS191 59 21. High Temperature Response, Vendor A, 54LS251 60 3 LIST OF FIGURES (continued) Figure No. Title Page 22. High
Distinct MicroRNA Expression Profile and Targeted Biological Pathways in Functional Myeloid-derived Suppressor Cells Induced by Δ9-Tetrahydrocannabinol in Vivo

PubMed Central

Hegde, Venkatesh L.; Tomar, Sunil; Jackson, Austin; Rao, Roshni; Yang, Xiaoming; Singh, Udai P.; Singh, Narendra P.; Nagarkatti, Prakash S.; Nagarkatti, Mitzi

2013-01-01

Δ9-Tetrahydrocannabinol (THC), the major bioactive component of marijuana, has been shown to induce functional myeloid-derived suppressor cells (MDSCs) in vivo. Here, we studied the involvement of microRNA (miRNA) in this process. CD11b+Gr-1+ MDSCs were purified from peritoneal exudates of mice administered with THC and used for genome-wide miRNA profiling. Expression of CD31 and Ki-67 confirmed that the THC-MDSCs were immature and proliferating. THC-induced MDSCs exhibited distinct miRNA expression signature relative to various myeloid cells and BM precursors. We identified 13 differentially expressed (>2-fold) miRNA in THC-MDSCs relative to control BM precursors. In silico target prediction for these miRNA and pathway analysis using multiple bioinformatics tools revealed significant overrepresentation of Gene Ontology clusters within hematopoiesis, myeloid cell differentiation, and regulation categories. Insulin-like growth factor 1 signaling involved in cell growth and proliferation, and myeloid differentiation pathways were among the most significantly enriched canonical pathways. Among the differentially expressed, miRNA-690 was highly overexpressed in THC-MDSCs (∼16-fold). Transcription factor CCAAT/enhancer-binding protein α (C/EBPα) was identified as a potential functional target of miR-690. Supporting this, C/EBPα expression was attenuated in THC-MDSCs as compared with BM precursors and exhibited an inverse relation with miR-690. miR-690 knockdown using peptide nucleic acid-antagomiR was able to unblock and significantly increase C/EBPα expression establishing the functional link. Further, CD11b+Ly6G+Ly6C+ and CD11b+Ly6G−Ly6C+ purified subtypes showed high levels of miR-690 with attenuated C/EBPα expression. Moreover, EL-4 tumor-elicited MDSCs showed increased miR-690 expression. In conclusion, miRNA are significantly altered during the generation of functional MDSC from BM. Select miRNA such as miR-690 targeting genes involved in myeloid expansion and differentiation likely play crucial roles in this process and therefore in cannabinoid-induced immunosuppression. PMID:24202177
Dynamic High-temperature Testing of an Iridium Alloy in Compression at High-strain Rates: Dynamic High-temperature Testing

DOE PAGES

Song, B.; Nelson, K.; Lipinski, R.; ...

2014-08-21

Iridium alloys have superior strength and ductility at elevated temperatures, making them useful as structural materials for certain high-temperature applications. However, experimental data on their high-strain -rate performance are needed for understanding high-speed impacts in severe environments. Kolsky bars (also called split Hopkinson bars) have been extensively employed for high-strain -rate characterization of materials at room temperature, but it has been challenging to adapt them for the measurement of dynamic properties at high temperatures. In our study, we analyzed the difficulties encountered in high-temperature Kolsky bar testing of thin iridium alloy specimens in compression. We made appropriate modifications using themore » current high-temperature Kolsky bar technique in order to obtain reliable compressive stress–strain response of an iridium alloy at high-strain rates (300–10 000 s -1) and temperatures (750 and 1030°C). The compressive stress–strain response of the iridium alloy showed significant sensitivity to both strain rate and temperature.« less
The Numerical Simulation of Time Dependent Flow Structures Over a Natural Gravel Surface.

NASA Astrophysics Data System (ADS)

Hardy, R. J.; Lane, S. N.; Ferguson, R. I.; Parsons, D. R.

2004-05-01

Research undertaken over the last few years has demonstrated the importance of the structure of gravel river beds for understanding the interaction between fluid flow and sediment transport processes. This includes the observation of periodic high-speed fluid wedges interconnected by low-speed flow regions. Our understanding of these flows has been enhanced significantly through a series of laboratory experiments and supported by field observations. However, the potential of high resolution three dimensional Computational Fluid Dynamics (CFD) modeling has yet to be fully developed. This is largely the result of the problems of designing numerically stable meshes for use with complex bed topographies and that Reynolds averaged turbulence schemes are applied. This paper develops two novel techniques for dealing with these issues. The first is the development and validation of a method for representing the complex surface topography of gravel-bed rivers in high resolution three-dimensional computational fluid dynamic models. This is based upon a porosity treatment with a regular structured grid and the application of a porosity modification to the mass conservation equation in which: fully blocked cells are assigned a porosity of zero; fully unblocked cells are assigned a porosity of one; and partly blocked cells are assigned a porosity of between 0 and 1, according to the percentage of the cell volume that is blocked. The second is the application of Large Eddy Simulation (LES) which enables time dependent flow structures to be numerically predicted over the complex bed topographies. The regular structured grid with the embedded porosity algorithm maintains a constant grid cell size throughout the domain implying a constant filter scale for the LES simulation. This enables the prediction of coherent structures, repetitive quasi-cyclic large-scale turbulent motions, over the gravel surface which are of a similar magnitude and frequency to those previously observed in both flume and field studies. These structures are formed by topographic forcing within the domain and are scaled with the flow depth. Finally, this provides the numerical framework for the prediction of sediment transport within a time dependent framework. The turbulent motions make a significant contribution to the turbulent shear stress and the pressure fluctuations which significantly affect the forces acting on the bed and potentially control sediment motion.
SU-E-J-56: Static Gantry Digital Tomosynthesis From the Beam’s-Eye-View

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

Partain, L; Kwon, J; Boyd, D

Purpose We have designed a novel TumoTrak™ x-ray system that delivers 19 distinct kV views with the linac gantry stationary. It images MV treatment beam above and below the patient with a kV tomosysthesis slice image from the therapy beam’s-eye-view. Results will be high quality images without MLC shadowing for notable improvements relative to conventional fluoroscopic MV imaging and fluoroscopic kV imaging. Methods A complete design has a kV electron beam multisource X-ray tube that fits around the MV treatment beam path, with little interference with normal radiotherapy and unblocked by the multi-leaf-collimator. To simulate digital tomosynthesis, we used cone-beammore » CT projection data from a lung SBRT patient. These data were acquired at 125 kVp and 11 fps (0.4 mAs per projection). We chose 19 projections evenly spaced over 27° around one of the treatment angles (240°). Digital tomosynthesis reconstruction of a slice through the tumor was performed using iterative reconstruction. The visibility of the lesion was assessed for the reconstructed digital tomosynthesis (DTS), using fluoroscopy MV images acquired during radiation therapy, and a kV single projection image acquired at the same angle as the treatment field (240°). Results The fluoroscopic DTS images provide the best tumor contrast, surpassing the conventional radiographic and the in-treatment MV portal images. The electron beam multisource X-ray tube design has been completed and the tube is being fabricated. The estimated time to cycle through all 19 projections is 700 ms, enabling high frame-rate imaging. While the initial proposed use case is for image guided and gated treatment delivery, the enhanced imaging will also deliver superior radiographic images for patient setup. Conclusion The proposed device will deliver high quality planar images from the beam’s-eye-view without MLC obstruction. The prototype has been designed and is being assembled with first imaging scheduled for May 2015. L. Partain, J. Kwon, D. Boyd: NIH/SBIR R43CA192489-01. J. Rottmann, G. Zentai, R. Berbeco: NIH/NCI 1R01CA188446-01. R. Berbeco: E. Research Grant, Varian Medical Systems.« less
Testing the effects of temperature and humidity on printed passive UHF RFID tags on paper substrate

NASA Astrophysics Data System (ADS)

Linnea Merilampi, Sari; Virkki, Johanna; Ukkonen, Leena; Sydänheimo, Lauri

2014-05-01

This article is an interesting substrate material for environmental-friendly printable electronics. In this study, screen-printed RFID tags on paper substrate are examined. Their reliability was tested with low temperature, high temperature, slow temperature cycling, high temperature and high humidity and water dipping test. Environmental stresses affect the tag antenna impedance, losses and radiation characteristics due to their impact on the ink film and paper substrate. Low temperature, temperature cycling and high humidity did not have a radical effect on the measured parameters: threshold power, backscattered signal power or read range of the tags. However, the frequency response and the losses of the tags were slightly affected. Exposure to high temperature was found to even improve the tag performance due to the positive effect of high temperature on the ink film. The combined high humidity and high temperature had the most severe effect on the tag performance. The threshold power increased, backscattered power decreased and the read range was shortened. On the whole, the results showed that field use of these tags in high, low and changing temperature conditions and high humidity conditions is possible. Use of these tags in combined high-humidity and high-temperature conditions should be carefully considered.
Late Carboniferous remagnetisation of Palaeozoic rocks in the NE Rhenish Massif, Germany

NASA Astrophysics Data System (ADS)

Zwing, A.; Bachtadse, V.; Soffel, H. C.

During stepwise thermal and alternating field demagnetisation experiments on Devonian and Lower Carboniferous carbonate and clastic rocks from the north-eastern part of the Rhenish Massif, Germany, three components of magnetisation (A, B, C) are identified. Component A is a recent viscous overprint that parallels the local present day geomagnetic field. Component B is mainly observed from 260 up to 550 °C during thermal demagnetisation and is carried by magnetite. In two localities, where red siltstones and red carbonate rocks were sampled, component B is stable up to 670 °C, indicating the presence of hematite. Three clusters of in situ B directions can be identified, which are controlled by the tectonic position of the sampling areas. These are from NW to SE: the Remscheid anticline (RA), the Lüdenscheid syncline (LS) and the Attendorn and Wittgenstein synclines (AS/WS). Standard and inclination-only fold tests, using parametric resampling, yield optimal statistical parameters at increasing amounts of untilting ranging from 0% in the South up to 57% in the North of the NE Rhenish Massif. Despite the variations in optimal untilting, the resulting site mean directions of component B do not differ significantly in inclination. These results are interpreted to reflect the acquisition of magnetisation during progressive northward migration of the deformation front in Late Carboniferous times. The resulting palaeolatitudes (RA: 1°S +2°-3°; LS: 2°S +3°-2°; AS/WS: 1°S +3°-4°) are in good agreement with the predicted position of the sampling area in the Late Carboniferous, as derived from a published Apparent Polar Wander Path for Baltica and Laurentia. The unblocking temperature spectra and the synfolding nature of B yield strong evidence that chemical processes, possibly driven by fluid migration during orogenesis, caused this remagnetisation. A third component C was observed in zones of tight folding with steeply dipping to overturned bedding planes and is dominantly carried by hematite. The resulting palaeolatitude (27°N +10°-8°) suggest a Late Triassic to Early Jurassic age of component C, which is interpreted to be caused by either hematite-bearing post-Variscan mineralisation or oxidising fluids percolating from the weathering surface and penetrating zones of enhanced permeability in the Mesozoic.
Thermomagnetic Stability in Pseudo Single Domain Grains

NASA Astrophysics Data System (ADS)

Nagy, Lesleis; Williams, Wyn; Muxworthy, Adrian; Fabian, Karl; Conbhuí, Pádraig Ó.

2016-04-01

The reliability of paleomagnetic remanences are well understood for fine grains of magnetite that are single-domain (SD, uniformly magnetized). In particular Néel's theory [1] outlined the thermal energies required to block and unblock magnetic remanences. This lead to determination of thermal stability for magnetization in fine grains as outlined in Pullaiah et. al. [2] and a comprehensive understanding of SD paleomagnetic recordings. It has been known for some time that single domain magnetite is possible only in the grain size range 30 - 80nm, which may only account for a small fraction of the grain size distribution in any rock sample. Indeed rocks are often dominated by grains in the pseudo single domain (PSD) size range, at approximately 80 - 1000nm. Toward the top end of this range multi-domain features begin to dominate. In order to determine thermomagnetic stability in PSD grains we need to identify the energy barriers between all possible pairs of local energy minima (LEM) domain states as a function of both temperature and grain size. We have attempted to do this using the nudged elastic band (NEB) method [3] which searches for minimum energy paths between any given pair of LEM states. Using this technique we have determined, for the first time, complete thermomagnetic stability curves for PSD magnetite. The work presented is at a preliminary stage. However it can be shown that PSD grains of magnetite with simple geometries (e.g. cubes or cuboctahedra) have very few low energy transition paths and the stability is likely to be similar to that observed for SD grains (as expected form experimental observations). The results will provide a basis for a much more rigorous understanding of the fidelity of paleomagnetic signals in assemblages of PSD grains and their ability to retain ancient recordings of the geomagnetic field. References: [1] Néel, Louis. "Théorie du traînage magnétique des ferromagnétiques en grains fins avec applications aux terres cuites." Ann. géophys 5.2 (1949): 99-136. [2] Pullaiah, G., et al. "Magnetization changes caused by burial and uplift." Earth and Planetary Science Letters 28.2 (1975): 133-143. [3] D. Sheppard, R. Terrell, and G. Henkelman, "Optimization methods for finding minimum energy paths", J. Chem. Phys. 128, 134106 (2008).
Ultrasonic Al₂O₃ Ceramic Thermometry in High-Temperature Oxidation Environment.

PubMed

Wei, Yanlong; Gao, Yubin; Xiao, Zhaoqian; Wang, Gao; Tian, Miao; Liang, Haijian

2016-11-11

In this study, an ultrasonic temperature measurement system was designed with Al₂O₃ high-temperature ceramic as an acoustic waveguide sensor and preliminarily tested in a high-temperature oxidation environment. The test results indicated that the system can indeed work stably in high-temperature environments. The relationship between the temperature and delay time of 26 °C-1600 °C ceramic materials was also determined in order to fully elucidate the high-temperature oxidation of the proposed waveguide sensor and to lay a foundation for the further application of this system in temperatures as high as 2000 °C.
High-temperature responses of North American cacti

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

Smith, S.D.; Didden-Zopfy, B.; Nobel, P.S.

1984-04-01

High-temperature tolerances of 14 species of North American cacti were investigated. A reduction in the proportion of chlorenchyma cells taking up a vital stain (neutral red) and reduced nocturnal acid accumulation were used as indicators of high-temperature damage. All species tolerated relatively high tissue temperatures, the mean maximum tolerance being 64/sup 0/C, with an absolute maximum of 69/sup 0/ for two species of ferocactus. Such tissue tolerances to high temperature may be unsurpassed in vascular plants. Morphological features can affect tissue temperatures. Specifically, thin-stemmed species such as the cylindropuntias attain lower maximum temperatures under identical microclimatic conditions than do moremore » massive species; they also tend to be less tolerant of high-temperature stress. Stem diameter changes of three species of columnar ceriod cacti along a Sonoran Desert latitudinal transect were previously attributed to adaptation to progressively colder temperatures northward. Such changes can also be interpreted as a morphological adaptation to high temperatures, particularly in the southern Sonoran Desert. Interspecific differences in high-temperature tolerance may account for distributional differences among other species. Acclimation of high-temperature tolerances in response to increasing day/night air temperatures was observed in all 14 species, especially at higher growh temperatures. From 40/sup 0/ day/30/sup 0/ night to 50/sup 0//40/sup 0/, the tolerable tissue temperatures increased an average of 6/sup 0/. Half-times for the acclimation shifts were 1-3d. Although cacti attain extremely high tissue temperatures in desert habitats, tolerance of high temperatures and pronounced acclimation potential allow them to occur in some of the hottest habitats in North America.« less
Effect of In-situ Cure on Measurement of Glass Transition Temperatures in High-temperature Thermosetting Polymers

DTIC Science & Technology

2015-01-01

TEMPERATURES IN HIGH-TEMPERATURE THERMOSETTING POLYMERS 5a. CONTRACT NUMBER In-House 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S...illustrated the difficulties inherent in measurement of the glass transition temperature of this high-temperature thermosetting polymer via dynamic...copyright protection in the United States. EFFECT OF IN-SITU CURE ON MEASUREMENT OF GLASS TRANSITION TEMPERATURES IN HIGH-TEMPERATURE THERMOSETTING
High-Temperature Piezoelectric Sensing

PubMed Central

Jiang, Xiaoning; Kim, Kyungrim; Zhang, Shujun; Johnson, Joseph; Salazar, Giovanni

2014-01-01

Piezoelectric sensing is of increasing interest for high-temperature applications in aerospace, automotive, power plants and material processing due to its low cost, compact sensor size and simple signal conditioning, in comparison with other high-temperature sensing techniques. This paper presented an overview of high-temperature piezoelectric sensing techniques. Firstly, different types of high-temperature piezoelectric single crystals, electrode materials, and their pros and cons are discussed. Secondly, recent work on high-temperature piezoelectric sensors including accelerometer, surface acoustic wave sensor, ultrasound transducer, acoustic emission sensor, gas sensor, and pressure sensor for temperatures up to 1,250 °C were reviewed. Finally, discussions of existing challenges and future work for high-temperature piezoelectric sensing are presented. PMID:24361928

Thellier's Betes Noires and how to Recognize Them

NASA Astrophysics Data System (ADS)

Dunlop, D. J.

2007-12-01

When Emile Thellier invented his classic paleointensity determination method, he made it quite clear that it applied only to NRMs which had originated as TRMs carried by non-interacting single-domain grains. Baked clays and bricks satisfied his stringent requirements but volcanic rocks were tested and rejected as unsuitable. While most paleomagnetists would regard Thellier's stance as unduly rigid, it certainly would help improve the usual dismal success rate in paleointensity studies if at the outset one could recognize and discard Thellierś betes noires: (1) NRMs of non-TRM origin, such as CRMs and TCRMs, which are particularly insidious because they may yield linear Arai plots with the wrong slope; (2) interacting grains, which compromise the independence of non-overlapping pTRMs; (3) grains larger than single-domain size with non-reciprocal blocking and unblocking. Pre-screening based on physical mechanisms would also be an improvement compared to relying solely on reliability parameters and checks. These are effective in detecting laboratory alteration of a rock but less so in filtering out samples which behave reversibly, yet are flawed recorders of the paleofield. FORC diagrams combine analysis of coercivity distribution, strength of interactions, and basic domain state. Their effectiveness in weeding out magnetic deviants has been demonstrated by Carvallo et al. (JGR 111, B12103, 2006). However, the CRM/TCRM problem remains severe. Almost all CRMs measured by Draeger et al. (GJI 166, 12-32, 2006) had ideal Arai plots but field intensity values were in error by as much as a factor 2. Unfortunately CRM/TCRM is not easily diagnosed in individual samples, and we are driven to reconsider Thellier's dictum: don't take risks by using rocks whose NRM could be other than TRM. Unfortunately this includes many attractive candidates, volcanic glasses, baked contacts and most metamorphic rocks among them. A crude approach might be to reject those samples in a collection whose NRM/SIRM ratios are conspicuously low compared to the average, although choosing the threshold for rejection would be highly subjective.
Anther response to high-temperature stress during development and pollen thermotolerance heterosis as revealed by pollen tube growth and in vitro pollen vigor analysis in upland cotton.

PubMed

Song, Guicheng; Wang, Miaomiao; Zeng, Bin; Zhang, Jing; Jiang, Chenliang; Hu, Qirui; Geng, Guangtao; Tang, Canming

2015-05-01

Pollen tube growth in styles was strongly inhibited by temperature above 35 °C, and the yield of cotton decreased because of the adverse effect of high temperatures during square development. High-temperature stress during flowering influences the square development of upland cotton (Gossypium hirsutum L.) and cotton yield. Although it is well known that square development is sensitive to high temperature, high-temperature sensitive stages of square development and the effects of high temperature on pollen tube growth in the styles are unknown. The effect of high temperature on anther development corresponding to pollen vigor is unknown during anther development. The objectives of this study were to identify the stages of square development that are sensitive to high temperatures (37/30 and 40/34 °C), to determine whether the abnormal development of squares influenced by high temperature is responsible for the variation in the in vitro germination percent of pollen grains at anthesis, to identify the effect of high temperature on pollen germination in the styles, and to determine pollen thermotolerance heterosis. Our results show that the stages from the sporogenous cell to tetrad stage (square length <6.0 mm) were the most sensitive to high temperature, and the corresponding pollen viability at anthesis was consistent with the changes in the square development stage. Pollen tube growth in the styles was strongly inhibited by temperature above 35 °C, and the yield of cotton decreased because of the effect of high temperature during square development. The thermotolerance of hybrid F1 pollen showed heterosis, and pollen viability could be used as a criterion for screening for high-temperature tolerance cultivars. These results can be used in breeding to develop new cotton cultivars that can withstand high-temperature conditions, particularly in a future warmer climate.
Body temperature and resistance to evaporative water loss in tropical Australian frogs.

PubMed

Tracy, Christopher R; Christian, Keith A; Betts, Gregory; Tracy, C Richard

2008-06-01

Although the skin of most amphibians measured to date offers no resistance to evaporative water loss (EWL), some species, primarily arboreal frogs, produce skin secretions that increase resistance to EWL. At high air temperatures, it may be advantageous for amphibians to increase EWL as a means to decrease body temperature. In Australian hylid frogs, most species do not decrease their resistance at high air temperature, but some species with moderate resistance (at moderate air temperatures) gradually decrease resistance with increasing air temperature, and some species with high resistance (at moderate air temperatures) abruptly decrease resistance at high air temperatures. Lower skin resistance at high air temperatures decreases the time to desiccation, but the lower body temperatures allow the species to avoid their critical thermal maximum (CT(Max)) body temperatures. The body temperatures of species with low to moderate resistances to EWL that do not adjust resistance at high air temperatures do not warm to their CT(Max), although for some species, this is because they have high CT(Max) values. As has been reported previously for resistance to EWL generally, the response pattern of change of EWL at high air temperatures has apparently evolved independently among Australian hylids. The mechanisms involved in causing resistance and changes in resistance are unknown.
Effects of high temperature after pollination on physicochemical properties of waxy maize flour during grain development.

PubMed

Lu, Dalei; Cai, Xuemei; Yan, Fabao; Sun, Xuli; Wang, Xin; Lu, Weiping

2014-05-01

Waxy maize is grown in South China, where high temperatures frequently prevail. The effect of high-temperature stress on grain development of waxy maize is not known. High temperature decreased the grain fresh weight and volume, and lowered the grain dry weight and water content after 22 days after pollination (DAP). Plants exposed to high temperature had low starch content, and high protein and soluble sugar contents at maturity. Starch iodine binding capacity and granule size were increased by heat stress at all grain-filling stages. The former parameter decreased, while the latter parameter increased gradually with grain development. High temperature increased the peak and breakdown viscosity before 30 DAP, but the value decreased at maturity. Pasting and gelatinization temperatures at different stages were increased by heat stress and gradually decreased with grain development under both high-temperature and control conditions. Gelatinization enthalpy increased initially but decreased after peaking at 22 DAP under both control and heat stress conditions. High temperature decreased gelatinization enthalpy after 10 DAP. Retrogradation percentage value increased with high temperature throughout grain development. High temperature after pollination changes the dynamics of grain filling of waxy maize, which may underlie the observed changes in its pasting and thermal properties. © 2013 Society of Chemical Industry.
The Analysis and Modeling of Phase Stability and Multiphase Designs in High Temperature Refractory Metal-Silicon-Boron Alloys

DTIC Science & Technology

2009-01-27

high temperature mechanical properties , it was confirmed that the three phase eutectic structure exhibited exceptionally high strength and creep...microstructurc constituent, offer an attractive property balance of high melting temperature, oxidation resistance and useful high temperature mechanical ...design of new multiphase high-temperature alloys with balanced environmental and mechanical properties . 15. SUBJECT TERMS Phase Stability, Alloying
Decreased photosynthetic rate under high temperature in wheat is due to lipid desaturation, oxidation, acylation, and damage of organelles.

PubMed

Djanaguiraman, M; Boyle, D L; Welti, R; Jagadish, S V K; Prasad, P V V

2018-04-05

High temperature is a major abiotic stress that limits wheat (Triticum aestivum L.) productivity. Variation in levels of a wide range of lipids, including stress-related molecular species, oxidative damage, cellular organization and ultrastructural changes were analyzed to provide an integrated view of the factors that underlie decreased photosynthetic rate under high temperature stress. Wheat plants of cultivar Chinese Spring were grown at optimum temperatures (25/15 °C, maximum/minimum) until the onset of the booting stage. Thereafter, plants were exposed to high temperature (35/25 °C) for 16 d. Compared with optimum temperature, a lower photosynthetic rate was observed at high temperature which is an interplay between thylakoid membrane damage, thylakoid membrane lipid composition, oxidative damage of cell organelle, and stomatal and non-stomatal limitations. Triacylglycerol levels were higher under high temperature stress. Polar lipid fatty acyl unsaturation was lower at high temperature, while triacylglycerol unsaturation was the same at high temperature and optimum temperature. The changes in lipid species indicates increases in activities of desaturating, oxidizing, glycosylating and acylating enzymes under high temperature stress. Cumulative effect of high temperature stress led to generation of reactive oxygen species, cell organelle and membrane damage, and reduced antioxidant enzyme activity, and imbalance between reactive oxygen species and antioxidant defense system. Taken together with recent findings demonstrating that reactive oxygen species are formed from and are removed by thylakoid lipids, the data suggest that reactive oxygen species production, reactive oxygen species removal, and changes in lipid metabolism contribute to decreased photosynthetic rate under high temperature stress.
DOE Office of Scientific and Technical Information (OSTI.GOV)

Song, Bo; Nelson, Kevin; Jin, Helena

Iridium alloys have been utilized as structural materials for certain high-temperature applications, due to their superior strength and ductility at elevated temperatures. The mechanical properties, including failure response at high strain rates and elevated temperatures of the iridium alloys need to be characterized to better understand high-speed impacts at elevated temperatures. A DOP-26 iridium alloy has been dynamically characterized in compression at elevated temperatures with high-temperature Kolsky compression bar techniques. However, the dynamic high-temperature compression tests were not able to provide sufficient dynamic high-temperature failure information of the iridium alloy. In this study, we modified current room-temperature Kolsky tension barmore » techniques for obtaining dynamic tensile stress-strain curves of the DOP-26 iridium alloy at two different strain rates (~1000 and ~3000 s-1) and temperatures (~750°C and ~1030°C). The effects of strain rate and temperature on the tensile stress-strain response of the iridium alloy were determined. The DOP-26 iridium alloy exhibited high ductility in stress-strain response that strongly depended on both strain rate and temperature.« less
A Eu/Tb-mixed MOF for luminescent high-temperature sensing

NASA Astrophysics Data System (ADS)

Wang, Huizhen; Zhao, Dian; Cui, Yuangjing; Yang, Yu; Qian, Guodong

2017-02-01

Temperature measurements and thermal mapping using luminescent MOF operating in the high-temperature range are of great interest in the micro-electronic diagnosis. In this paper, we report a thermostable Eu/Tb-mixed MOF Eu0.37Tb0.63-BTC-a exhibiting strong luminescence at elevated temperature, which can serve as a ratiometric luminescent thermometer for high-temperature range. The high-temperature operating range (313-473 K), high relative sensitivity and accurate temperature resolution, make such a Eu/Tb-mixed MOF useful for micro-electronic diagnosis.
Relative sensitivity of five Hawaiian coral species to high temperature under high-pCO2 conditions

NASA Astrophysics Data System (ADS)

Bahr, Keisha D.; Jokiel, Paul L.; Rodgers, Ku'ulei S.

2016-06-01

Coral reef ecosystems are presently undergoing decline due to anthropogenic climate change. The chief detrimental factors are increased temperature and increased pCO2. The purpose of this study was to evaluate the effect of these two stressors operating independently and in unison on the biological response of common Hawaiian reef corals. Manipulative experiments were performed using five species ( Porites compressa, Pocillopora damicornis, Fungia scutaria, Montipora capitata, and Leptastrea purpurea) in a continuous-flow mesocosm system under natural sunlight conditions. Corals were grown together as a community under treatments of high temperature (2 °C above normal maximum summer temperature), high pCO2 (twice present-day conditions), and with both factors acting in unison. Control corals were grown under present-day pCO2 and at normal summer temperatures. Leptastrea purpurea proved to be an extremely hardy coral. No change in calcification or mortality occurred under treatments of high temperature, high pCO2, or combined high temperature-high pCO2. The remaining four species showed reduced calcification in the high-temperature treatment. Two species ( L. purpurea and M. capitata) showed no response to increased pCO2. Also, high pCO2 ameliorated the negative effect of high temperature on the calcification rates of P. damicornis. Mortality was driven primarily by high temperature, with a negative synergistic effect in P. compressa only in the high-pCO2-high-temperature treatment. Results support the observation that biological response to temperature and pCO2 elevation is highly species-specific, so generalizations based on response of a single species might not apply to a diverse and complex coral reef community.
High temperature superconducting composite conductor and method for manufacturing the same

DOEpatents

Holesinger, Terry G.; Bingert, John F.

2002-01-01

A high temperature superconducting composite conductor is provided including a high temperature superconducting material surrounded by a noble metal layer, the high temperature superconducting composite conductor characterized as having a fill factor of greater than about 40. Additionally, the conductor can be further characterized as containing multiple cores of high temperature superconducting material surrounded by a noble metal layer, said multiple cores characterized as having substantially uniform geometry in the cross-sectional dimensions. Processes of forming such a high temperature superconducting composite conductor are also provided.
[Multi-temporal scale analysis of impacts of extreme high temperature on net carbon uptake in subtropical coniferous plantation.

PubMed

Zhang, Mi; Wen, Xue Fa; Zhang, Lei Ming; Wang, Hui Min; Guo, Yi Wen; Yu, Gui Rui

2018-02-01

Extreme high temperature is one of important extreme weathers that impact forest ecosystem carbon cycle. In this study, applying CO 2 flux and routine meteorological data measured during 2003-2012, we examined the impacts of extreme high temperature and extreme high temperature event on net carbon uptake of subtropical coniferous plantation in Qianyanzhou. Combining with wavelet analysis, we analyzed environmental controls on net carbon uptake at different temporal scales, when the extreme high temperature and extreme high temperature event happened. The results showed that mean daily cumulative NEE decreased by 51% in the days with daily maximum air temperature range between 35 ℃ and 40 ℃, compared with that in the days with the range between 30 ℃ and 34 ℃. The effects of the extreme high temperature and extreme high temperature event on monthly NEE and annual NEE related to the strength and duration of extreme high tempe-rature event. In 2003, when strong extreme high temperature event happened, the sum of monthly cumulative NEE in July and August was only -11.64 g C·m -2 ·(2 month) -1 . The value decreased by 90%, compared with multi-year average value. At the same time, the relative variation of annual NEE reached -6.7%. In July and August, when the extreme high temperature and extreme high temperature event occurred, air temperature (T a ) and vapor press deficit (VPD) were the dominant controller for the daily variation of NEE. The coherency between NEE T a and NEE VPD was 0.97 and 0.95, respectively. At 8-, 16-, and 32-day periods, T a , VPD, soil water content at 5 cm depth (SWC), and precipitation (P) controlled NEE. The coherency between NEE SWC and NEE P was higher than 0.8 at monthly scale. The results indicated that atmospheric water deficit impacted NEE at short temporal scale, when the extreme high temperature and extreme high temperature event occurred, both of atmospheric water deficit and soil drought stress impacted NEE at long temporal scales in this ecosystem.
Economic status and temperature-related mortality in Asia

NASA Astrophysics Data System (ADS)

Lim, Youn-Hee; Bell, Michelle L.; Kan, Haidong; Honda, Yasushi; Guo, Yue-Liang Leon; Kim, Ho

2015-10-01

In developed countries, low latitude and high temperature are positively associated with the population's ability to adapt to heat. However, few studies have examined the effect of economic status on the relationship between long-term exposure to high temperature and health. We compared heterogeneous temperature-related mortality effects relative to the average summer temperature in high-socioeconomic-status (SES) cities to temperature-related effects in low-SES cities. In the first stage of the research, we conducted a linear regression analysis to quantify the mortality effects of high temperature (at or above the 95th percentile) in 32 cities in Taiwan, China, Japan, and Korea. In the second stage, we used a meta-regression to examine the association between mortality risk with average summer temperature and gross domestic product (GDP) per capita. In cities with a low GDP per capita (less than 20,000 USD), the effects of temperature were detrimental to the population if the long-term average summer temperature was high. In contrast, in cities with a high GDP per capita, temperature-related mortality risk was not significantly related to average summer temperature. The relationship between long-term average summer temperature and the short-term effects of high temperatures differed based on the city-level economic status.
Responses of Rapid Viscoanalyzer Profile and Other Rice Grain Qualities to Exogenously Applied Plant Growth Regulators under High Day and High Night Temperatures

PubMed Central

Fahad, Shah; Hussain, Saddam; Saud, Shah; Hassan, Shah; Chauhan, Bhagirath Singh; Khan, Fahad; Ihsan, Muhammad Zahid; Ullah, Abid; Wu, Chao; Bajwa, Ali Ahsan; Alharby, Hesham; Amanullah; Nasim, Wajid; Shahzad, Babar; Tanveer, Mohsin; Huang, Jianliang

2016-01-01

High-temperature stress degrades the grain quality of rice; nevertheless, the exogenous application of plant growth regulators (PGRs) might alleviate the negative effects of high temperatures. In the present study, we investigated the responses of rice grain quality to exogenously applied PGRs under high day temperatures (HDT) and high night temperatures (HNT) under controlled conditions. Four different combinations of ascorbic acid (Vc), alpha-tocopherol (Ve), brassinosteroids (Br), methyl jasmonates (MeJA) and triazoles (Tr) were exogenously applied to two rice cultivars (IR-64 and Huanghuazhan) prior to the high-temperature treatment. A Nothing applied Control (NAC) was included for comparison. The results demonstrated that high-temperature stress was detrimental for grain appearance and milling qualities and that both HDT and HNT reduced the grain length, grain width, grain area, head rice percentage and milled rice percentage but increased the chalkiness percentage and percent area of endosperm chalkiness in both cultivars compared with ambient temperature (AT). Significantly higher grain breakdown, set back, consistence viscosity and gelatinization temperature, and significantly lower peak, trough and final viscosities were observed under high-temperature stress compared with AT. Thus, HNT was more devastating for grain quality than HDT. The exogenous application of PGRs ameliorated the adverse effects of high temperature in both rice cultivars, and Vc+Ve+MejA+Br was the best combination for both cultivars under high temperature stress. PMID:27472200
Reduction of pyruvate orthophosphate dikinase activity is associated with high temperature-induced chalkiness in rice grains.

PubMed

Wang, Zhen-mei; Li, Hai-xia; Liu, Xiong-feng; He, Ying; Zeng, Han-lai

2015-04-01

Global warming affects both rice (Oryza sativa) yields and grain quality. Rice chalkiness due to high temperature during grain filling would lower the grain quality. The biochemical and molecular mechanisms responsible for the increased occurrence of chalkiness under high temperature are not fully understood. Previous research suggested that cytosolic pyruvate orthophosphate dikinase (cyPPDK, EC 2.7.9.1) in rice modulates carbon metabolism. The objective of this study was to determine the relationship between cyPPDK and high temperature-induced chalkiness. High temperature treatments were applied during the grain filling of two rice cultivars (9311 and TXZ-25) which had different sensitivity of chalkiness to high temperature. Chalkiness was increased significantly under high temperature treatment, especially for TXZ-25. A shortened grain filling duration and a decreased grain weight in both cultivars were caused by high temperature treatment. A reduction in PPDK activities due to high temperature was observed during the middle and late grain filling periods, accompanied by down regulated cyPPDK mRNA and protein levels. The temperature effects on the developmental regulation of PPDK activity were confirmed at transcription, translation and post-translational levels. PPDK activities were insensitive to variation in PPDK levels, suggesting the rapid phosphorylation mechanism of this protein. The two varieties showed similar responses to the high temperature treatment in both PPDK activities and chalkiness. We concluded that high temperature-induced chalkiness was associated with the reduction of PPDK activity. Copyright © 2015 Elsevier Masson SAS. All rights reserved.
Identification of High-Temperature-Responsive Genes in Cereals1[C][W

PubMed Central

Hemming, Megan N.; Walford, Sally A.; Fieg, Sarah; Dennis, Elizabeth S.; Trevaskis, Ben

2012-01-01

High temperature influences plant development and can reduce crop yields. We examined how ambient temperature influences reproductive development in the temperate cereals wheat (Triticum aestivum) and barley (Hordeum vulgare). High temperature resulted in rapid progression through reproductive development in long days, but inhibited early stages of reproductive development in short days. Activation of the long-day flowering response pathway through day-length-insensitive alleles of the PHOTOPERIOD1 gene, which result in high FLOWERING LOCUS T-like1 transcript levels, did not allow rapid early reproductive development at high temperature in short days. Furthermore, high temperature did not increase transcript levels of FLOWERING LOCUS T-like genes. These data suggest that genes or pathways other than the long-day response pathway mediate developmental responses to high temperature in cereals. Transcriptome analyses suggested a possible role for vernalization-responsive genes in the developmental response to high temperature. The MADS-box floral repressor HvODDSOC2 is expressed at elevated levels at high temperature in short days, and might contribute to the inhibition of early reproductive development under these conditions. FLOWERING PROMOTING FACTOR1-like, RNase-S-like genes, and VER2-like genes were also identified as candidates for high-temperature-responsive developmental regulators. Overall, these data suggest that rising temperatures might elicit different developmental responses in cereal crops at different latitudes or times of year, due to the interaction between temperature and day length. Additionally, we suggest that different developmental regulators might mediate the response to high temperature in cereals compared to Arabidopsis (Arabidopsis thaliana). PMID:22279145
DOE Office of Scientific and Technical Information (OSTI.GOV)

Song, B.; Nelson, K.; Lipinski, R.

Iridium alloys have superior strength and ductility at elevated temperatures, making them useful as structural materials for certain high-temperature applications. However, experimental data on their high-strain -rate performance are needed for understanding high-speed impacts in severe environments. Kolsky bars (also called split Hopkinson bars) have been extensively employed for high-strain -rate characterization of materials at room temperature, but it has been challenging to adapt them for the measurement of dynamic properties at high temperatures. In our study, we analyzed the difficulties encountered in high-temperature Kolsky bar testing of thin iridium alloy specimens in compression. We made appropriate modifications using themore » current high-temperature Kolsky bar technique in order to obtain reliable compressive stress–strain response of an iridium alloy at high-strain rates (300–10 000 s -1) and temperatures (750 and 1030°C). The compressive stress–strain response of the iridium alloy showed significant sensitivity to both strain rate and temperature.« less
Rate-dependent activation failure in isolated cardiac cells and tissue due to Na+ channel block.

PubMed

Varghese, Anthony; Spindler, Anthony J; Paterson, David; Noble, Denis

2015-11-15

While it is well established that class-I antiarrhythmics block cardiac sodium channels, the mechanism of action of therapeutic levels of these drugs is not well understood. Using a combination of mathematical modeling and in vitro experiments, we studied the failure of activation of action potentials in single ventricular cells and in tissue caused by Na(+) channel block. Our computations of block and unblock of sodium channels by a theoretical class-Ib antiarrhythmic agent predict differences in the concentrations required to cause activation failure in single cells as opposed to multicellular preparations. We tested and confirmed these in silico predictions with in vitro experiments on isolated guinea-pig ventricular cells and papillary muscles stimulated at various rates (2-6.67 Hz) and exposed to various concentrations (5 × 10(-6) to 500 × 10(-6) mol/l) of lidocaine. The most salient result was that whereas large doses (5 × 10(-4) mol/l or higher) of lidocaine were required to inhibit action potentials temporarily in single cells, much lower doses (5 × 10(-6) mol/l), i.e., therapeutic levels, were sufficient to have the same effect in papillary muscles: a hundredfold difference. Our experimental results and mathematical analysis indicate that the syncytial nature of cardiac tissue explains the effects of clinically relevant doses of Na(+) channel blockers. Copyright © 2015 the American Physiological Society.
Rate-dependent activation failure in isolated cardiac cells and tissue due to Na+ channel block

PubMed Central

Spindler, Anthony J.; Paterson, David; Noble, Denis

2015-01-01

While it is well established that class-I antiarrhythmics block cardiac sodium channels, the mechanism of action of therapeutic levels of these drugs is not well understood. Using a combination of mathematical modeling and in vitro experiments, we studied the failure of activation of action potentials in single ventricular cells and in tissue caused by Na+ channel block. Our computations of block and unblock of sodium channels by a theoretical class-Ib antiarrhythmic agent predict differences in the concentrations required to cause activation failure in single cells as opposed to multicellular preparations. We tested and confirmed these in silico predictions with in vitro experiments on isolated guinea-pig ventricular cells and papillary muscles stimulated at various rates (2–6.67 Hz) and exposed to various concentrations (5 × 10−6 to 500 × 10−6 mol/l) of lidocaine. The most salient result was that whereas large doses (5 × 10−4 mol/l or higher) of lidocaine were required to inhibit action potentials temporarily in single cells, much lower doses (5 × 10−6 mol/l), i.e., therapeutic levels, were sufficient to have the same effect in papillary muscles: a hundredfold difference. Our experimental results and mathematical analysis indicate that the syncytial nature of cardiac tissue explains the effects of clinically relevant doses of Na+ channel blockers. PMID:26342072
Progress in improving provincial plans for nutrition through targeted technical assistance and local advocacy in Vietnam.

PubMed

Harris, Jody; Nguyen, Phuong H; To, Quyen; Frongillo, Edward A; Menon, Purnima

2016-12-01

Vietnam has been decentralizing nutrition planning to provinces, which could help with local relevance and accountability. Assessment in 2009 found a continuing top-down approach, limited human capacity, and difficulty in integrating multiple sectors. Alive and Thrive (A&T) provided targeted assistance and capacity-building for 15 provincial plans for nutrition (PPNs). We aimed to (i) assess PPN content and quality improvements 2009-2014, and (ii) explain processes through which change occurred. Data consisted of interview-based assessments of provincial planning processes, annual PPN assessments, and tracking of A&T involvement. At endline, some provinces produced higher quality plans. Local planning skills improved, but capacity remained insufficient. Awareness of and support for nutrition improved, but some policy and legal environments were contradictory. Objectives were clearer, but use of data for planning remained inconsistent. Provinces became more proactive and creative, but remained constrained by slow approval processes and insufficient funding. Targeted assistance and local advocacy can improve decentralized planning, with success dependent on policy and programming contexts and ability to overcome constraints around capacity, investment, data use and remnants of centralized planning. We recommend strong engagement with planners at the national level to understand how to unblock major constraints; solutions must take into consideration the particular political, financial and administrative context. © The Author 2016. Published by Oxford University Press in association with The London School of Hygiene and Tropical Medicine.
A nonlinear electrostatic potential change in the T-system of skeletal muscle detected under passive recording conditions using potentiometric dyes

PubMed Central

1990-01-01

Voltage-sensing dyes were used to examine the electrical behavior of the T-system under passive recording conditions similar to those commonly used to detect charge movement. These conditions are designed to eliminate all ionic currents and render the T-system potential linear with respect to the command potential applied at the surface membrane. However, we found an unexpected nonlinearity in the relationship between the dye signal from the T-system and the applied clamp potential. An additional voltage- and time-dependent optical signal appears over the same depolarizing range of potentials where change movement and mechanical activation occur. This nonlinearity is not associated with unblocked ionic currents and cannot be attributed to lack of voltage clamp control of the T-system, which appears to be good under these conditions. We propose that a local electrostatic potential change occurs in the T-system upon depolarization. An electrostatic potential would not be expected to extend beyond molecular distances of the membrane and therefore would be sensed by a charged dye in the membrane but not by the voltage clamp, which responds solely to the potential of the bulk solution. Results obtained with different dyes suggest that the location of the phenomena giving rise to the extra absorbance change is either intramembrane or at the inner surface of the T-system membrane. PMID:2299329

Opioid receptors mediate direct predictive fear learning: evidence from one-trial blocking.

PubMed

Cole, Sindy; McNally, Gavan P

2007-04-01

Pavlovian fear learning depends on predictive error, so that fear learning occurs when the actual outcome of a conditioning trial exceeds the expected outcome. Previous research has shown that opioid receptors, including mu-opioid receptors in the ventrolateral quadrant of the midbrain periaqueductal gray (vlPAG), mediate such predictive fear learning. Four experiments reported here used a within-subject one-trial blocking design to study whether opioid receptors mediate a direct or indirect action of predictive error on Pavlovian association formation. In Stage I, rats were trained to fear conditioned stimulus (CS) A by pairing it with shock. In Stage II, CSA and CSB were co-presented once and co-terminated with shock. Two novel stimuli, CSC and CSD, were also co-presented once and co-terminated with shock in Stage II. The results showed one-trial blocking of fear learning (Experiment 1) as well as one-trial unblocking of fear learning when Stage II training employed a higher intensity footshock than was used in Stage I (Experiment 2). Systemic administrations of the opioid receptor antagonist naloxone (Experiment 3) or intra-vlPAG administrations of the selective mu-opioid receptor antagonist CTAP (Experiment 4) prior to Stage II training prevented one-trial blocking. These results show that opioid receptors mediate the direct actions of predictive error on Pavlovian association formation.
The psychologizing of Chinese healing practices in the United States.

PubMed

Barnes, L L

1998-12-01

This paper explores ways in which Chinese healing practices have undergone acculturation in the United States since the early 1970s. Reacting to what is perceived as biomedicine's focus on the physiological, those who describe themselves as favoring a holistic orientation often use the language of "energy blockage" to explain illness, whether thought of as "physical," "emotional," or "spiritual." Acupuncture in particular has been appropriated as one modality with which to "unblock" such conditions, leading to its being used by some practitioners in conjunction with more psychotherapeutic approaches which include valuing the verbalizing of feelings. Some non-Chinese practitioners in the United States, returning to older Chinese texts to develop "an American acupuncture," are reinserting diagnoses eliminated from Traditional Chinese Medicine (TCM) by the People's Republic of China as "superstition." The assumption has been that many such diagnostic categories refer to psychological or spiritual conditions, and therefore may be useful in those American contexts which favor this orientation. Among these categories are those drawn from traditions of demonology in Chinese medicine. What was once a religious category in China turns psychological in the American setting. At the same time, many who use these terms have, since the late 1960s, increasingly conflated the psychological and the religious, the latter being reframed as "spiritual." Thus, this indigenization of Chinese practices is a complex synthesis which can be described as simultaneously medical, psychotherapeutic, and religious.
Emergence of periodic order in electric-field-driven planar nematic liquid crystals: An exclusive ac effect absent in static fields

NASA Astrophysics Data System (ADS)

Krishnamurthy, K. S.; Kumar, Pramoda

2007-11-01

We report, for a nematic liquid crystal with a low conductivity anisotropy, an ac field generated transition from a uniformly planar to a periodically modulated director configuration with the wave vector parallel to the initial director. Significantly, with unblocked electrodes, this instability is not excited by dc fields. Additionally, in very low frequency square wave fields, it occurs transiently after each polarity reversal, vanishing completely during field constancy. The time of occurrence of maximum distortion after polarity reversal decreases exponentially with voltage. The time dependence of optical phase change during transient distortion is nearly Gaussian. The pattern threshold Vc is linear in f , f denoting the frequency; the critical wave number qc of the modulation scales nearly linearly as f to a peak at ˜50Hz before falling slightly thereafter. The observed Vc(f) and qc(f) characteristics differ from the predictions of the standard model (SM). The instability may be interpreted as a special case of the Carr-Helfrich distortion suppressed in static fields due to weak charge focusing and strong charge injection. Its transient nature in the low frequency regime is suggestive of the possible role of gradient flexoelectric effect in its occurrence. The study includes measurement of certain elastic and viscosity parameters relevant to the application of the SM.
Technology Requirements and Development for Affordable High-Temperature Distributed Engine Controls

DTIC Science & Technology

2012-06-04

long lasting, high temperature modules is to use high temperature electronics on ceramic modules. The electronic components are “ brazed ” onto the...Copyright © 2012 by ISA Technology Requirements and Development for Affordable High - Temperature Distributed Engine Controls Alireza Behbahani 1...with regards to high temperature capability. The Government and Industry Distributed Engine Controls Working Group (DECWG) [5] has been established
Optimization of Multilayer Laminated Film and Absorbent of Vacuum Insulation Panel for Use at High Temperature

NASA Astrophysics Data System (ADS)

Araki, Kuninari; Echigoya, Wataru; Tsuruga, Toshimitsu; Kamoto, Daigorou; Matsuoka, Shin-Ichi

For the energy saving regulation and larger capacity, Vacuum Insulation Panel (VIP) has been used in refrigerators with urethane foam in recent years. VIP for low temperature is constructed by laminated plastic film, using heat welding of each neighboring part for keeping vacuum, so that the performance decrement is very large under high temperature. But recently high efficiency insulation material is desired for high temperature water holding devices (automatic vending machine, heat pump water heater, electric hot-water pot water, etc.), and we especially focused on cost and ability of the laminated plastic film and absorbent for high temperature VIP. We measured the heatproof temperature of plastic films and checked the amount of water vapor and out coming gas on temperature-programmed adsorption in absorbent. These results suggest the suitable laminated film and absorbent system for VIP use at high temperature, and the long-term reliability was evaluated by measuring thermal conductivity of high temperature. As a result it was found that high-retort pouch of CPP (cast polypropylene film) and adding of aluminum coating are the most suitable materials for use in the welded layers of high-temperature VIPs (105°C).
ABA-insensitive3, ABA-insensitive5, and DELLAs Interact to activate the expression of SOMNUS and other high-temperature-inducible genes in imbibed seeds in Arabidopsis.

PubMed

Lim, Soohwan; Park, Jeongmoo; Lee, Nayoung; Jeong, Jinkil; Toh, Shigeo; Watanabe, Asuka; Kim, Junghyun; Kang, Hyojin; Kim, Dong Hwan; Kawakami, Naoto; Choi, Giltsu

2013-12-01

Seeds monitor the environment to germinate at the proper time, but different species respond differently to environmental conditions, particularly light and temperature. In Arabidopsis thaliana, light promotes germination but high temperature suppresses germination. We previously reported that light promotes germination by repressing SOMNUS (SOM). Here, we examined whether high temperature also regulates germination through SOM and found that high temperature activates SOM expression. Consistent with this, som mutants germinated more frequently than the wild type at high temperature. The induction of SOM mRNA at high temperature required abscisic acid (ABA) and gibberellic acid biosynthesis, and ABA-insensitive3 (ABI3), ABI5, and DELLAs positively regulated SOM expression. Chromatin immunoprecipitation assays indicated that ABI3, ABI5, and DELLAs all target the SOM promoter. At the protein level, ABI3, ABI5, and DELLAs all interact with each other, suggesting that they form a complex on the SOM promoter to activate SOM expression at high temperature. We found that high-temperature-inducible genes frequently have RY motifs and ABA-responsive elements in their promoters, some of which are targeted by ABI3, ABI5, and DELLAs in vivo. Taken together, our data indicate that ABI3, ABI5, and DELLAs mediate high-temperature signaling to activate the expression of SOM and other high-temperature-inducible genes, thereby inhibiting seed germination.
Packaging Technology for SiC High Temperature Electronics

NASA Technical Reports Server (NTRS)

Chen, Liang-Yu; Neudeck, Philip G.; Spry, David J.; Meredith, Roger D.; Nakley, Leah M.; Beheim, Glenn M.; Hunter, Gary W.

2017-01-01

High-temperature environment operable sensors and electronics are required for long-term exploration of Venus and distributed control of next generation aeronautical engines. Various silicon carbide (SiC) high temperature sensors, actuators, and electronics have been demonstrated at and above 500 C. A compatible packaging system is essential for long-term testing and application of high temperature electronics and sensors in relevant environments. This talk will discuss a ceramic packaging system developed for high temperature electronics, and related testing results of SiC integrated circuits at 500 C facilitated by this high temperature packaging system, including the most recent progress.
Study Progress of Physiological Responses in High Temperature Environment

NASA Astrophysics Data System (ADS)

Li, K.; Zheng, G. Z.; Bu, W. T.; Wang, Y. J.; Lu, Y. Z.

2017-10-01

Certain workers are exposed to high temperatures for a long time. Heat stress will result in a series of physiological responses, and cause adverse effects on the health and safety of workers. This paper summarizes the physiological changes of cardiovascular system, core temperature, skin temperature, water-electrolyte metabolism, alimentary system, neuroendocrine system, reaction time and thermal fatigue in high temperature environments. It can provide a theoretical guidance for labor safety in high temperature environment.
High temperature furnace

DOEpatents

Borkowski, Casimer J.

1976-08-03

A high temperature furnace for use above 2000.degree.C is provided that features fast initial heating and low power consumption at the operating temperature. The cathode is initially heated by joule heating followed by electron emission heating at the operating temperature. The cathode is designed for routine large temperature excursions without being subjected to high thermal stresses. A further characteristic of the device is the elimination of any ceramic components from the high temperature zone of the furnace.
Identification of microRNAs associated with the exogenous spermidine-mediated improvement of high-temperature tolerance in cucumber seedlings (Cucumis sativus L.).

PubMed

Wang, Ying; Guo, Shirong; Wang, Lei; Wang, Liwei; He, Xueying; Shu, Sheng; Sun, Jin; Lu, Na

2018-04-24

High-temperature stress inhibited the growth of cucumber seedlings. Foliar spraying of 1.0 mmol·L - 1 exogenous spermidine (Spd) to the sensitive cucumber cultivar 'Jinchun No. 2' grown at high-temperature (42 °C/32 °C) in an artificial climate box improved the high-temperature tolerance. Although there have been many reports on the response of microRNAs (miRNAs) to high-temperature stress, the mechanism by which exogenous Spd may mitigate the damage of high-temperature stress through miRNA-mediated regulation has not been studied. To elucidate the regulation of miRNAs in response to exogenous Spd-mediated improvement of high-temperature tolerance, four small RNA libraries were constructed from cucumber leaves and sequenced: untreated-control (CW), Spd-treated (CS), high-temperature stress (HW), and Spd-treated and high-temperature stress (HS). As a result, 107 known miRNAs and 79 novel miRNAs were identified. Eight common differentially expressed miRNAs (miR156d-3p, miR170-5p, miR2275-5p, miR394a, miR479b, miR5077, miR5222 and miR6475) were observed in CS/CW, HW/CW, HS/CW and HS/HW comparison pairs, which were the first set of miRNAs that responded to not only high-temperature stress but also exogenous Spd in cucumber seedlings. Five of the eight miRNAs were predicted to target 107 potential genes. Gene function and pathway analyses highlighted the integral role that these miRNAs and target genes probably play in the improvement of the high-temperature tolerance of cucumber seedlings through exogenous Spd application. Our study identified the first set of miRNAs associated with the exogenous Spd-mediated improvement of high-temperature tolerance in cucumber seedlings. The results could help to promote further studies on the complex molecular mechanisms underlying high-temperature tolerance in cucumber and provide a theoretical basis for the high-quality and efficient cultivation of cucumber with high-temperature resistance.
High Temperature Chemistry at NASA: Hot Topics

NASA Technical Reports Server (NTRS)

Jacobson, Nathan S.

2014-01-01

High Temperature issues in aircraft engines Hot section: Ni and Co based Superalloys Oxidation and Corrosion (Durability) at high temperatures. Thermal protection system (TPS) and RCC (Reinforced Carbon-Carbon) on the Space Shuttle Orbiter. High temperatures in other worlds: Planets close to their stars.
High-temperature testing of high performance fiber reinforced concrete

NASA Astrophysics Data System (ADS)

Fořt, Jan; Vejmelková, Eva; Pavlíková, Milena; Trník, Anton; Čítek, David; Kolísko, Jiří; Černý, Robert; Pavlík, Zbyšek

2016-06-01

The effect of high-temperature exposure on properties of High Performance Fiber Reinforced Concrete (HPFRC) is researched in the paper. At first, reference measurements are done on HPFRC samples without high-temperature loading. Then, the HPFRC samples are exposed to the temperatures of 200, 400, 600, 800, and 1000 °C. For the temperature loaded samples, measurement of residual mechanical and basic physical properties is done. Linear thermal expansion coefficient as function of temperature is accessed on the basis of measured thermal strain data. Additionally, simultaneous difference scanning calorimetry (DSC) and thermogravimetry (TG) analysis is performed in order to observe and explain material changes at elevated temperature. It is found that the applied high temperature loading significantly increases material porosity due to the physical, chemical and combined damage of material inner structure, and negatively affects also the mechanical strength. Linear thermal expansion coefficient exhibits significant dependence on temperature and changes of material structure. The obtained data will find use as input material parameters for modelling the damage of HPFRC structures exposed to the fire and high temperature action.
Low temperature superconductor and aligned high temperature superconductor magnetic dipole system and method for producing high magnetic fields

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

Gupta, Ramesh; Scanlan, Ronald; Ghosh, Arup K.

A dipole-magnet system and method for producing high-magnetic-fields, including an open-region located in a radially-central-region to allow particle-beam transport and other uses, low-temperature-superconducting-coils comprised of low-temperature-superconducting-wire located in radially-outward-regions to generate high magnetic-fields, high-temperature-superconducting-coils comprised of high-temperature-superconducting-tape located in radially-inward-regions to generate even higher magnetic-fields and to reduce erroneous fields, support-structures to support the coils against large Lorentz-forces, a liquid-helium-system to cool the coils, and electrical-contacts to allow electric-current into and out of the coils. The high-temperature-superconducting-tape may be comprised of bismuth-strontium-calcium-copper-oxide or rare-earth-metal, barium-copper-oxide (ReBCO) where the rare-earth-metal may be yttrium, samarium, neodymium, or gadolinium. Advantageously, alignment of themore » large-dimension of the rectangular-cross-section or curved-cross-section of the high-temperature-superconducting-tape with the high-magnetic-field minimizes unwanted erroneous magnetic fields. Alignment may be accomplished by proper positioning, tilting the high-temperature-superconducting-coils, forming the high-temperature-superconducting-coils into a curved-cross-section, placing nonconducting wedge-shaped-material between windings, placing nonconducting curved-and-wedge-shaped-material between windings, or by a combination of these techniques.« less
Low to moderate temperature nanolaminate heater

DOEpatents

Eckels, J Del [Livermore, CA; Nunes, Peter J [Danville, CA; Simpson, Randall L [Livermore, CA; Hau-Riege, Stefan [Fremont, CA; Walton, Chris [Oakland, CA; Carter, J Chance [Livermore, CA; Reynolds, John G [San Ramon, CA

2011-01-11

A low to moderate temperature heat source comprising a high temperature energy source modified to output low to moderate temperatures wherein the high temperature energy source modified to output low to moderate temperatures is positioned between two thin pieces to form a close contact sheath. In one embodiment the high temperature energy source modified to output low to moderate temperatures is a nanolaminate multilayer foil of reactive materials that produces a heating level of less than 200.degree. C.
Hydrogen Production from Nuclear Energy via High Temperature Electrolysis

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

James E. O'Brien; Carl M. Stoots; J. Stephen Herring

2006-04-01

This paper presents the technical case for high-temperature nuclear hydrogen production. A general thermodynamic analysis of hydrogen production based on high-temperature thermal water splitting processes is presented. Specific details of hydrogen production based on high-temperature electrolysis are also provided, including results of recent experiments performed at the Idaho National Laboratory. Based on these results, high-temperature electrolysis appears to be a promising technology for efficient large-scale hydrogen production.
Separating heat stress from moisture stress: analyzing yield response to high temperature in irrigated maize

NASA Astrophysics Data System (ADS)

Carter, Elizabeth K.; Melkonian, Jeff; Riha, Susan J.; Shaw, Stephen B.

2016-09-01

Several recent studies have indicated that high air temperatures are limiting maize (Zea mays L.) yields in the US Corn Belt and project significant yield losses with expected increases in growing season temperatures. Further work has suggested that high air temperatures are indicative of high evaporative demand, and that decreases in maize yields which correlate to high temperatures and vapor pressure deficits (VPD) likely reflect underlying soil moisture limitations. It remains unclear whether direct high temperature impacts on yields, independent of moisture stress, can be observed under current temperature regimes. Given that projected high temperature and moisture may not co-vary the same way as they have historically, quantitative analyzes of direct temperature impacts are critical for accurate yield projections and targeted mitigation strategies under shifting temperature regimes. To evaluate yield response to above optimum temperatures independent of soil moisture stress, we analyzed climate impacts on irrigated maize yields obtained from the National Corn Growers Association (NCGA) corn yield contests for Nebraska, Kansas and Missouri. In irrigated maize, we found no evidence of a direct negative impact on yield by daytime air temperature, calculated canopy temperature, or VPD when analyzed seasonally. Solar radiation was the primary yield-limiting climate variable. Our analyses suggested that elevated night temperature impacted yield by increasing rates of phenological development. High temperatures during grain-fill significantly interacted with yields, but this effect was often beneficial and included evidence of acquired thermo-tolerance. Furthermore, genetics and management—information uniquely available in the NCGA contest data—explained more yield variability than climate, and significantly modified crop response to climate. Thermo-acclimation, improved genetics and changes to management practices have the potential to partially or completely offset temperature-related yield losses in irrigated maize.
High-temperature microphone system. [for measuring pressure fluctuations in gases at high temperature

NASA Technical Reports Server (NTRS)

Zuckerwar, A. J. (Inventor)

1979-01-01

Pressure fluctuations in air or other gases in an area of elevated temperature are measured using a condenser microphone located in the area of elevated temperature and electronics for processing changes in the microphone capacitance located outside the area the area and connected to the microphone by means of high-temperature cable assembly. The microphone includes apparatus for decreasing the undesirable change in microphone sensitivity at high temperatures. The high temperature cable assembly operates as a half-wavelength transmission line in an AM carrier system and maintains a large temperature gradient between the two ends of the cable assembly. The processing electronics utilizes a voltage controlled oscillator for automatic tuning thereby increasing the sensitivity of the measuring apparatus.
Passive Resistor Temperature Compensation for a High-Temperature Piezoresistive Pressure Sensor.

PubMed

Yao, Zong; Liang, Ting; Jia, Pinggang; Hong, Yingping; Qi, Lei; Lei, Cheng; Zhang, Bin; Li, Wangwang; Zhang, Diya; Xiong, Jijun

2016-07-22

The main limitation of high-temperature piezoresistive pressure sensors is the variation of output voltage with operating temperature, which seriously reduces their measurement accuracy. This paper presents a passive resistor temperature compensation technique whose parameters are calculated using differential equations. Unlike traditional experiential arithmetic, the differential equations are independent of the parameter deviation among the piezoresistors of the microelectromechanical pressure sensor and the residual stress caused by the fabrication process or a mismatch in the thermal expansion coefficients. The differential equations are solved using calibration data from uncompensated high-temperature piezoresistive pressure sensors. Tests conducted on the calibrated equipment at various temperatures and pressures show that the passive resistor temperature compensation produces a remarkable effect. Additionally, a high-temperature signal-conditioning circuit is used to improve the output sensitivity of the sensor, which can be reduced by the temperature compensation. Compared to traditional experiential arithmetic, the proposed passive resistor temperature compensation technique exhibits less temperature drift and is expected to be highly applicable for pressure measurements in harsh environments with large temperature variations.
Passive Resistor Temperature Compensation for a High-Temperature Piezoresistive Pressure Sensor

PubMed Central

Yao, Zong; Liang, Ting; Jia, Pinggang; Hong, Yingping; Qi, Lei; Lei, Cheng; Zhang, Bin; Li, Wangwang; Zhang, Diya; Xiong, Jijun

2016-01-01

The main limitation of high-temperature piezoresistive pressure sensors is the variation of output voltage with operating temperature, which seriously reduces their measurement accuracy. This paper presents a passive resistor temperature compensation technique whose parameters are calculated using differential equations. Unlike traditional experiential arithmetic, the differential equations are independent of the parameter deviation among the piezoresistors of the microelectromechanical pressure sensor and the residual stress caused by the fabrication process or a mismatch in the thermal expansion coefficients. The differential equations are solved using calibration data from uncompensated high-temperature piezoresistive pressure sensors. Tests conducted on the calibrated equipment at various temperatures and pressures show that the passive resistor temperature compensation produces a remarkable effect. Additionally, a high-temperature signal-conditioning circuit is used to improve the output sensitivity of the sensor, which can be reduced by the temperature compensation. Compared to traditional experiential arithmetic, the proposed passive resistor temperature compensation technique exhibits less temperature drift and is expected to be highly applicable for pressure measurements in harsh environments with large temperature variations. PMID:27455271
Climate Change: A New Metric to Measure Changes in the Frequency of Extreme Temperatures using Record Data

NASA Technical Reports Server (NTRS)

Munasinghe, L.; Jun, T.; Rind, D. H.

2012-01-01

Consensus on global warming is the result of multiple and varying lines of evidence, and one key ramification is the increase in frequency of extreme climate events including record high temperatures. Here we develop a metric- called "record equivalent draws" (RED)-based on record high (low) temperature observations, and show that changes in RED approximate changes in the likelihood of extreme high (low) temperatures. Since we also show that this metric is independent of the specifics of the underlying temperature distributions, RED estimates can be aggregated across different climates to provide a genuinely global assessment of climate change. Using data on monthly average temperatures across the global landmass we find that the frequency of extreme high temperatures increased 10-fold between the first three decades of the last century (1900-1929) and the most recent decade (1999-2008). A more disaggregated analysis shows that the increase in frequency of extreme high temperatures is greater in the tropics than in higher latitudes, a pattern that is not indicated by changes in mean temperature. Our RED estimates also suggest concurrent increases in the frequency of both extreme high and extreme low temperatures during 2002-2008, a period when we observe a plateauing of global mean temperature. Using daily extreme temperature observations, we find that the frequency of extreme high temperatures is greater in the daily minimum temperature time-series compared to the daily maximum temperature time-series. There is no such observable difference in the frequency of extreme low temperatures between the daily minimum and daily maximum.

ABA-INSENSITIVE3, ABA-INSENSITIVE5, and DELLAs Interact to Activate the Expression of SOMNUS and Other High-Temperature-Inducible Genes in Imbibed Seeds in Arabidopsis[W

PubMed Central

Lim, Soohwan; Park, Jeongmoo; Lee, Nayoung; Jeong, Jinkil; Toh, Shigeo; Watanabe, Asuka; Kim, Junghyun; Kang, Hyojin; Kim, Dong Hwan; Kawakami, Naoto; Choi, Giltsu

2013-01-01

Seeds monitor the environment to germinate at the proper time, but different species respond differently to environmental conditions, particularly light and temperature. In Arabidopsis thaliana, light promotes germination but high temperature suppresses germination. We previously reported that light promotes germination by repressing SOMNUS (SOM). Here, we examined whether high temperature also regulates germination through SOM and found that high temperature activates SOM expression. Consistent with this, som mutants germinated more frequently than the wild type at high temperature. The induction of SOM mRNA at high temperature required abscisic acid (ABA) and gibberellic acid biosynthesis, and ABA-INSENSITIVE3 (ABI3), ABI5, and DELLAs positively regulated SOM expression. Chromatin immunoprecipitation assays indicated that ABI3, ABI5, and DELLAs all target the SOM promoter. At the protein level, ABI3, ABI5, and DELLAs all interact with each other, suggesting that they form a complex on the SOM promoter to activate SOM expression at high temperature. We found that high-temperature-inducible genes frequently have RY motifs and ABA-responsive elements in their promoters, some of which are targeted by ABI3, ABI5, and DELLAs in vivo. Taken together, our data indicate that ABI3, ABI5, and DELLAs mediate high-temperature signaling to activate the expression of SOM and other high-temperature-inducible genes, thereby inhibiting seed germination. PMID:24326588
High-Temperature Resistance Strain Gauges

NASA Technical Reports Server (NTRS)

Lei, Jih-Fen

1994-01-01

Resistance strain gauges developed for use at high temperatures in demanding applications like testing aircraft engines and structures. Measures static strains at temperatures up to 800 degrees C. Small and highly reproducible. Readings corrected for temperature within small tolerances, provided temperatures measured simultaneously by thermocouples or other suitable devices. Connected in wheatstone bridge.
Refractory thermowell for continuous high temperature measurement of molten metal

DOEpatents

Thiesen, Todd J.

1992-01-01

An apparatus for the continuous high temperature measurement of materials in vessels lined with rammed or cast refractory materials. A refractory housing member is integral with the refractory lining of the vessel and contains a plurality of high temperature sensing means, such as thermocouples. A face of the housing is flush with the refractory lining and contacts the high temperature material contained in the vessel. Continuous temperature measurement is achieved by a means which is coupled to the thermocouples for indicating the temperature.
HIGH-TEMPERATURE AND HIGH-PRESSURE PARTICULATE CONTROL REQUIREMENTS

EPA Science Inventory

The report reviews and evaluates high-temperature and high-pressure particulate cleanup requirements of existing and proposed energy processes. The study's aims are to define specific high-temperature and high-pressure particle removal problems, to indicate potential solutions, a...
High-temperature langatate elastic constants and experimental validation up to 900 degrees C.

PubMed

Davulis, Peter M; da Cunha, Mauricio Pereira

2010-01-01

This paper reports on a set of langatate (LGT) elastic constants extracted from room temperature to 1100 degrees C using resonant ultrasound spectroscopy techniques and an accompanying assessment of these constants at high temperature. The evaluation of the constants employed SAW device measurements from room temperature to 900 degrees C along 6 different LGT wafer orientations. Langatate parallelepipeds and wafers were aligned, cut, ground, and polished, and acoustic wave devices were fabricated at the University of Maine facilities along specific orientations for elastic constant extraction and validation. SAW delay lines were fabricated on LGT wafers prepared at the University of Maine using 100-nm platinumrhodium- zirconia electrodes capable of withstanding temperatures up to 1000 degrees C. The numerical predictions based on the resonant ultrasound spectroscopy high-temperature constants were compared with SAW phase velocity, fractional frequency variation, and temperature coefficients of delay extracted from SAW delay line frequency response measurements. In particular, the difference between measured and predicted fractional frequency variation is less than 2% over the 25 degrees C to 900 degrees C temperature range and within the calculated and measured discrepancies. Multiple temperature-compensated orientations at high temperature were predicted and verified in this paper: 4 of the measured orientations had turnover temperatures (temperature coefficient of delay = 0) between 200 and 420 degrees C, and 2 had turnover temperatures below 100 degrees C. In summary, this work reports on extracted high-temperature elastic constants for LGT up to 1100 degrees C, confirmed the validity of those constants by high-temperature SAW device measurements up to 900 degrees C, and predicted and identified temperature-compensated LGT orientations at high temperature.
Consecutive record-breaking high temperatures marked the handover from hiatus to accelerated warming

PubMed Central

Su, Jingzhi; Zhang, Renhe; Wang, Huijun

2017-01-01

Closely following the hiatus warming period, two astonishing high temperature records reached in 2014 and 2015 consecutively. To investigate the occurrence features of record-breaking high temperatures in recent years, a new index focusing the frequency of the top 10 high annual mean temperatures was defined in this study. Analyses based on this index shown that record-breaking high temperatures occurred over most regions of the globe with a salient increasing trend after 1960 s, even during the so-called hiatus period. Overlapped on the ongoing background warming trend and the interdecadal climate variabilities, the El Niño events, particularly the strong ones, can make a significant contribution to the occurrence of high temperatures on interannual timescale. High temperatures associated with El Niño events mainly occurred during the winter annual period. As the Pacific Decadal Oscillation (PDO) struggled back to its positive phase since 2014, the global warming returned back to a new accelerated warming period, marked by the record-breaking high temperatures in 2014. Intensified by the super strong El Niño, successive high records occurred in 2015 and 2016. Higher frequencies of record high temperatures would occur in the near future because the PDO tends to maintain a continuously positive phase. PMID:28256561
Review on fatigue behavior of high-strength concrete after high temperature

NASA Astrophysics Data System (ADS)

Zhao, Dongfu; Jia, Penghe; Gao, Haijing

2017-06-01

The fatigue of high-strength concrete after high temperature has begun to attract attention. But so far the researches work about the fatigue of high-strength concrete after high temperature have not been reported. This article based on a large number of literature. The research work about the fatigue of high-strength concrete after high temperature are reviewed, analysed and expected, which can provide some reference for the experimental study of fatigue damage analysis.
Dynamic, High-Temperature, Flexible Seal

NASA Technical Reports Server (NTRS)

Steinetz, Bruce M.; Sirocky, Paul J.

1989-01-01

New seal consists of multiple plies of braided ceramic sleeves filled with small ceramic balls. Innermost braided sleeve supported by high-temperature-wire-mesh sleeve that provides both springback and preload capabilities. Ceramic balls reduce effect of relatively high porosity of braided ceramic sleeves by acting as labyrinth flow path for gases and thereby greatly increasing pressure gradient seal can sustain. Dynamic, high-temperature, flexible seal employed in hypersonic engines, two-dimensional convergent/divergent and vectorized-thrust exhaust nozzles, reentry vehicle airframes, rocket-motor casings, high-temperature furnaces, and any application requiring non-asbestos high-temperature gaskets.
Alumina ceramic based high-temperature performance of wireless passive pressure sensor

NASA Astrophysics Data System (ADS)

Wang, Bo; Wu, Guozhu; Guo, Tao; Tan, Qiulin

2016-12-01

A wireless passive pressure sensor equivalent to inductive-capacitive (LC) resonance circuit and based on alumina ceramic is fabricated by using high temperature sintering ceramic and post-fire metallization processes. Cylindrical copper spiral reader antenna and insulation layer are designed to realize the wireless measurement for the sensor in high temperature environment. The high temperature performance of the sensor is analyzed and discussed by studying the phase-frequency and amplitude-frequency characteristics of reader antenna. The average frequency change of sensor is 0.68 kHz/°C when the temperature changes from 27°C to 700°C and the relative change of twice measurements is 2.12%, with high characteristic of repeatability. The study of temperature-drift characteristic of pressure sensor in high temperature environment lays a good basis for the temperature compensation methods and insures the pressure signal readout accurately.
[Response and adaptation of photosynthesis of cucumber seedlings to high temperature stress].

PubMed

Sun, Sheng Nan; Wang, Qiang; Sun, Chen Chen; Liu, Feng Jiao; Bi, Huan Gai; Ai, Xi Zhen

2017-05-18

Cucumber seedlings (Cucumis sativus Jinyou 35) were used to study the effects of high temperature (HT: 42 ℃/32 ℃) and sub-high temperature (SHT: 35 ℃/25 ℃) on its photosynthesis and growth. The results showed that the growth of cucumber seedlings was dramatically inhibited by the high and sub-high temperature stresses. The photosynthetic rate (P n ) was gradually reduced, while intercellular CO 2 concentration (C i ) was increased as heat stress lasted. Under heat stress, stomatal conductance (g s ), transpiration rate (T r ), photorespiration rate (P r ) and dark respiration rate (D r ) showed a trend from rise to decline in cucumber seedlings, which implied that heat-induced decline of photosynthesis was mainly due to non-stomatal limitation. Maximal photochemical efficiency of PS2 in darkness (F v /F m ), actual photochemical efficiency (χ PS 2 ), photochemical quenching (q P ) and electron transport rate (ETR) were severely hampered, while initial fluorescence (F o ) and non-chemical quenching (NPQ) were increased as a result of high and sub-high temperature stresses. Under extended high temperature stress, the activities of RuBP carboxylase (RuBPCase) and Rubisco activase (RCA) as well as the mRNA abundance of Rubisco and RCA were in the trend of decrease, while they were reduced 3 days following the sub-high temperature treatment. The activities and mRNA expressions of sedoheptulose-1,7-bisphosphatase (SBPase) and fructose 1,6-bisphosphate aldolase (FBA) increased initially, but decreased afterwards under heat stress. Taken together, our data suggested that short-term sub-high temperature did not cause photoinhibition under optimal light conditions, however, high temperature led to severe damage to PS2 reaction center in cucumber seedlings. The photosynthetic enzymes were induced by high temperature stress and the induction was affected by temperature and stress duration.
High Speed, High Temperature, Fault Tolerant Operation of a Combination Magnetic-Hydrostatic Bearing Rotor Support System for Turbomachinery

NASA Technical Reports Server (NTRS)

Jansen, Mark; Montague, Gerald; Provenza, Andrew; Palazzolo, Alan

2004-01-01

Closed loop operation of a single, high temperature magnetic radial bearing to 30,000 RPM (2.25 million DN) and 540 C (1000 F) is discussed. Also, high temperature, fault tolerant operation for the three axis system is examined. A novel, hydrostatic backup bearing system was employed to attain high speed, high temperature, lubrication free support of the entire rotor system. The hydrostatic bearings were made of a high lubricity material and acted as journal-type backup bearings. New, high temperature displacement sensors were successfully employed to monitor shaft position throughout the entire temperature range and are described in this paper. Control of the system was accomplished through a stand alone, high speed computer controller and it was used to run both the fault-tolerant PID and active vibration control algorithms.
Nonlinear Constitutive Relations for High Temperature Application, 1984

NASA Technical Reports Server (NTRS)

1985-01-01

Nonlinear constitutive relations for high temperature applications were discussed. The state of the art in nonlinear constitutive modeling of high temperature materials was reviewed and the need for future research and development efforts in this area was identified. Considerable research efforts are urgently needed in the development of nonlinear constitutive relations for high temperature applications prompted by recent advances in high temperature materials technology and new demands on material and component performance. Topics discussed include: constitutive modeling, numerical methods, material testing, and structural applications.
A High Temperature Silicon Carbide mosfet Power Module With Integrated Silicon-On-Insulator-Based Gate Drive

DOE PAGES

Wang, Zhiqiang; Shi, Xiaojie; Tolbert, Leon M.; ...

2014-04-30

Here we present a board-level integrated silicon carbide (SiC) MOSFET power module for high temperature and high power density application. Specifically, a silicon-on-insulator (SOI)-based gate driver capable of operating at 200°C ambient temperature is designed and fabricated. The sourcing and sinking current capability of the gate driver are tested under various ambient temperatures. Also, a 1200 V/100 A SiC MOSFET phase-leg power module is developed utilizing high temperature packaging technologies. The static characteristics, switching performance, and short-circuit behavior of the fabricated power module are fully evaluated at different temperatures. Moreover, a buck converter prototype composed of the SOI gate drivermore » and SiC power module is built for high temperature continuous operation. The converter is operated at different switching frequencies up to 100 kHz, with its junction temperature monitored by a thermosensitive electrical parameter and compared with thermal simulation results. The experimental results from the continuous operation demonstrate the high temperature capability of the power module at a junction temperature greater than 225°C.« less
Effect of In-Situ Cure on Measurement of Glass Transition Temperatures in High-Temperature Thermosetting Polymers (Briefing Charts)

DTIC Science & Technology

2015-05-20

TEMPERATURES IN HIGH-TEMPERATURE THERMOSETTING POLYMERS 5a. CONTRACT NUMBER In-House 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) 5d...temperature thermosetting polymer via dynamic mechanical analysis alone. These difficulties result from the residual cure of samples heated beyond their...98) Prescribed by ANSI Std. 239.18 Effect of In-Situ Cure on Measurement of Glass Transition Temperatures in High-Temperature Thermosetting
A measurement system of high-temperature oxidation environment with ultrasonic Ir0.6Rth0.4 alloy thermometry.

PubMed

Wei, Yanlong; Wang, Gao; Gao, Yubin; Liu, Zhengguang; Xu, Lin; Tian, Miao; Yuan, Dongfang; Ren, Haiping; Zhou, Hanchang; Yang, Lu; Shi, Xueshun; Xiao, Zhaoqian

2018-04-03

Iridium-rhodium is generally applied as a thermocouple material, with max operating temperature about 2150 °C. In this study, a ultrasonic temperature measurement system was designed by using Iridium-rhodium (60%Ir-40%Rh) alloy as an acoustic waveguide sensor material, and the system was preliminarily tested in a high-temperature oxidation environment. The result of ultrasonic temperature measurement shows that this system can indeed work stably in high-temperature oxidation environments. The relationship between temperature and delay time of ultrasonic thermometry up to 2200 °C was illustrated. Iridium-rhodium materials were also investigated in order to fully elucidate the proposed waveguide sensor's performance in a high-temperature oxidation environment. This system lays a foundation for further application of high-temperature measurement. Copyright © 2018. Published by Elsevier B.V.
Deep Trek High Temperature Electronics Project

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

Bruce Ohme

2007-07-31

This report summarizes technical progress achieved during the cooperative research agreement between Honeywell and U.S. Department of Energy to develop high-temperature electronics. Objects of this development included Silicon-on-Insulator (SOI) wafer process development for high temperature, supporting design tools and libraries, and high temperature integrated circuit component development including FPGA, EEPROM, high-resolution A-to-D converter, and a precision amplifier.
Acousto-optic Imaging System for In-situ Measurement of the High Temperature Distribution in Micron-size Specimens

NASA Astrophysics Data System (ADS)

Machikhin, Alexander S.; Zinin, Pavel V.; Shurygin, Alexander V.

We developed a unique acousto-optic imaging system for in-situ measurement of high temperature distribution on micron-size specimens. The system was designed to measure temperature distribution inside minerals and functional material phases subjected to high pressure and high temperatures in a diamond anvil cell (DAC) heated by a high powered laser.
Shear wave EMAT thickness measurements of low carbon steel at 450 °C without cooling

NASA Astrophysics Data System (ADS)

Lunn, Natasha; Potter, Mark; Dixon, Steve

2017-02-01

Performing high temperature online inspection without plant shutdown is highly desirable, yet, development of portable or permanently installed high temperature ultrasonic sensors, without the need for sample surface preparation, remains a key challenge. Low carbon steel pipelines operating at elevated temperatures often develop a magnetostrictive oxide coating (magnetite), which improves electromagnetic acoustic transducer (EMAT) efficiency below the Curie temperature of magnetite (575 °C), via a magnetostrictive mechanism. Coupling the inherent non-contacting nature of EMATs with the enhanced efficiency from a magnetite coating, we are able to continuously operate an uncoded EMAT at elevated temperatures without permanent installation or surface preparation. In this work, a high temperature shear wave EMAT utilizing a high field, high Curie point, permanent magnet has been developed to generate ultrasonic bulk thickness measurements on magnetite coated steel at temperatures of up to 450 °C, without cooling. Relatively high signal-to-noise ratios, in the region of 30 dB for single shot data, have been measured at 450 °C using this technique. The EMAT design and results from high temperature trials, including the performance with change in temperature, sample thickness and EMAT-sample lift-off, are presented here.
Measurement of high-dynamic temperature field using high-speed quadriwave lateral shearing interferometer

NASA Astrophysics Data System (ADS)

Cui, Bo-chuan; Wang, Jian-li; Yao, Kai-nan; Chen, Tao

2018-03-01

An approach to measure a high-dynamic two-dimensional (2D) temperature field using a high-speed quadriwave lateral shearing interferometer (QWLSI) is proposed. The detailed theoretical derivation to express the wavefront reconstruct principle of the proposed method is presented. The comparison experiment with thermocouples shows that the temperature field measurement using QWLSI has a precision of ±0.5 °C. An experiment for measuring the highdynamic temperature field generated by an electrical heater is carried out. A 200 frame rate temperature field video with 512 × 512 resolution is obtained finally. Experimental results show that the temperature field measurement system using a QWLSI has the advantage of high sensitivity and high resolution.
Impact of high temperature stress on floret fertility and individual grain weight of grain sorghum: sensitive stages and thresholds for temperature and duration

PubMed Central

Prasad, P. V. V.; Djanaguiraman, Maduraimuthu; Perumal, Ramasamy; Ciampitti, Ignacio A.

2015-01-01

Sorghum [Sorghum bicolor (L.) Moench] yield formation is severely affected by high temperature stress during reproductive stages. This study pursues to (i) identify the growth stage(s) most sensitive to high temperature stress during reproductive development, (ii) determine threshold temperature and duration of high temperature stress that decreases floret fertility and individual grain weight, and (iii) quantify impact of high daytime temperature during floret development, flowering and grain filling on reproductive traits and grain yield under field conditions. Periods between 10 and 5 d before anthesis; and between 5 d before- and 5 d after-anthesis were most sensitive to high temperatures causing maximum decreases in floret fertility. Mean daily temperatures >25°C quadratically decreased floret fertility (reaching 0% at 37°C) when imposed at the start of panicle emergence. Temperatures ranging from 25 to 37°C quadratically decreased individual grain weight when imposed at the start of grain filling. Both floret fertility and individual grain weights decreased quadratically with increasing duration (0–35 d or 49 d during floret development or grain filling stage, respectively) of high temperature stress. In field conditions, imposition of temperature stress (using heat tents) during floret development or grain filling stage also decreased floret fertility, individual grain weight, and grain weight per panicle. PMID:26500664

Comparison of the temperature accuracy between smart phone based and high-end thermal cameras using a temperature gradient phantom

NASA Astrophysics Data System (ADS)

Klaessens, John H.; van der Veen, Albert; Verdaasdonk, Rudolf M.

2017-03-01

Recently, low cost smart phone based thermal cameras are being considered to be used in a clinical setting for monitoring physiological temperature responses such as: body temperature change, local inflammations, perfusion changes or (burn) wound healing. These thermal cameras contain uncooled micro-bolometers with an internal calibration check and have a temperature resolution of 0.1 degree. For clinical applications a fast quality measurement before use is required (absolute temperature check) and quality control (stability, repeatability, absolute temperature, absolute temperature differences) should be performed regularly. Therefore, a calibrated temperature phantom has been developed based on thermistor heating on both ends of a black coated metal strip to create a controllable temperature gradient from room temperature 26 °C up to 100 °C. The absolute temperatures on the strip are determined with software controlled 5 PT-1000 sensors using lookup tables. In this study 3 FLIR-ONE cameras and one high end camera were checked with this temperature phantom. The results show a relative good agreement between both low-cost and high-end camera's and the phantom temperature gradient, with temperature differences of 1 degree up to 6 degrees between the camera's and the phantom. The measurements were repeated as to absolute temperature and temperature stability over the sensor area. Both low-cost and high-end thermal cameras measured relative temperature changes with high accuracy and absolute temperatures with constant deviations. Low-cost smart phone based thermal cameras can be a good alternative to high-end thermal cameras for routine clinical measurements, appropriate to the research question, providing regular calibration checks for quality control.
Method of manufacturing a high temperature superconductor with improved transport properties

DOEpatents

Balachandran, Uthamalingam; Siegel, Richard W.; Askew, Thomas R.

2001-01-01

A method of preparing a high temperature superconductor. A method of preparing a superconductor includes providing a powdered high temperature superconductor and a nanophase paramagnetic material. These components are combined to form a solid compacted mass with the paramagnetic material disposed on the grain boundaries of the polycrystaline high temperature superconductor.
[Study of high temperature water vapor concentration measurement method based on absorption spectroscopy].

PubMed

Chen, Jiu-ying; Liu, Jian-guo; He, Jun-feng; He, Ya-bai; Zhang, Guang-le; Xu, Zhen-yu; Gang, Qiang; Wang, Liao; Yao, Lu; Yuan, Song; Ruan, Jun; Dai, Yun-hai; Kan, Rui-feng

2014-12-01

Tunable diode laser absorption spectroscopy (TDLAS) has been developed to realize the real-time and dynamic measurement of the combustion temperature, gas component concentration, velocity and other flow parameters, owing to its high sensitivity, fast time response, non-invasive character and robust nature. In order to obtain accurate water vapor concentration at high temperature, several absorption spectra of water vapor near 1.39 μm from 773 to 1273 K under ordinary pressure were recorded in a high temperature experiment setup using a narrow band diode laser. The absorbance of high temperature absorption spectra was calculated by combined multi-line nonlinear least squares fitting method. Two water vapor absorption lines near 7154.35 and 7157.73 cm(-1) were selected for measurement of water vapor at high temperature. A model method for high temperature water vapor concentration was first proposed. Water vapor concentration from the model method at high temperature is in accordance with theoretical reasoning, concentration measurement standard error is less than 0.2%, and the relative error is less than 6%. The feasibility of this measuring method is verified by experiment.
Development of Metal Oxide Nanostructure-based Optical Sensors for Fossil Fuel Derived Gases Measurement at High Temperature

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

Chen, Kevin P.

2015-02-13

This final technical report details research works performed supported by a Department of Energy grant (DE-FE0003859), which was awarded under the University Coal Research Program administrated by National Energy Technology Laboratory. This research program studied high temperature fiber sensor for harsh environment applications. It developed two fiber optical sensor platform technology including regenerative fiber Bragg grating sensors and distributed fiber optical sensing based on Rayleigh backscattering optical frequency domain reflectometry. Through the studies of chemical and thermal regenerative techniques for fiber Bragg grating (FBG) fabrication, high-temperature stable FBG sensors were successfully developed and fabricated in air-hole microstructured fibers, high-attenuation fibers,more » rare-earth doped fibers, and standard telecommunication fibers. By optimizing the laser processing and thermal annealing procedures, fiber grating sensors with stable performance up to 1100°C have been developed. Using these temperature-stable FBG gratings as sensor platform, fiber optical flow, temperature, pressure, and chemical sensors have been developed to operate at high temperatures up to 800°C. Through the integration of on-fiber functional coating, the use of application-specific air-hole microstructural fiber, and application of active fiber sensing scheme, distributed fiber sensor for temperature, pressure, flow, liquid level, and chemical sensing have been demonstrated with high spatial resolution (1-cm or better) with wide temperature ranges. These include the demonstration of 1) liquid level sensing from 77K to the room temperature, pressure/temperature sensing from the room temperature to 800C and from the 15psi to 2000 psi, and hydrogen concentration measurement from 0.2% to 10% with temperature ranges from the room temperature to 700°C. Optical sensors developed by this program has broken several technical records including flow sensors with the highest operation temperature up to 750°C, first distributed chemical measurements at the record high temperature up to 700°C, first distributed pressure measurement at the record high temperature up to 800°C, and the fiber laser sensors with the record high operation temperature up to 700°C. The research performed by this program dramatically expand the functionality, adaptability, and applicability of distributed fiber optical sensors with potential applications in a number of high-temperature energy systems such as fossil-fuel power generation, high-temperature fuel cell applications, and potential for nuclear energy systems.« less
Application of TL dosemeters for dose distribution measurements at high temperatures in nuclear reactors.

PubMed

Osvay, M; Deme, S

2006-01-01

Al2O3:Mg,Y ceramic thermoluminescence dosemeters were developed at the Institute of Isotopes for high dose applications at room temperatures. The glow curve of Al2O3:Mg,Y exhibits two peaks--one at 250 degrees C (I) and another peak at approximately 400 degrees C (II). In order to extend the application of these dosemeters to high temperatures, the effect of irradiation temperature was investigated using temperature controlled heating system during high dose irradiation at various temperatures (20-100 degrees C). The new calibration and measuring method has been successfully applied for dose mapping within the hermetic zone of the Paks Nuclear Power Plant even at high temperature parts of blocks.
High- and low-temperature-stable thermite composition for producing high-pressure, high-velocity gases

DOEpatents

Halcomb, Danny L.; Mohler, Jonathan H.

1990-10-16

A high- and low-temperature-stable thermite composition for producing high-pressure and high-velocity gases comprises an oxidizable metal, an oxidizing reagent, and a high-temperature-stable gas-producing additive selected from the group consisting of metal carbides and metal nitrides.
High refractive index and temperature sensitivity LPGs for high temperature operation

NASA Astrophysics Data System (ADS)

Nascimento, I. M.; Gouveia, C.; Jana, Surnimal; Bera, Susanta; Baptista, J. M.; Moreira, Paulo; Biwas, Palas; Bandyopadhyay, Somnath; Jorge, Pedro A. S.

2013-11-01

A fiber optic sensor for high sensitivity refractive index and temperature measurement able to withstand temperature up to 450 °C is reported. Two identical LPG gratings were fabricated, whereas one was coated with a high refractive index (~1.78) sol-gel thin film in order to increase its sensitivity to the external refractive index. The two sensors were characterized and compared in refractive index and temperature. Sensitivities of 1063 nm/RIU (1.338 - 1.348) and 260 pm/°C were achieved for refractive index and temperature, respectively.
Temperature compensated high-temperature/high-pressure Merrill--Bassett diamond anvil cell

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

Schiferl, D.

1987-07-01

A Merrill--Bassett diamond anvil cell for high-temperature/high-pressure studies up to 5 GPa at 1000 K and 13 GPa at 725 K is described. To maintain uniform, well-characterized temperatures, and to protect the diamond anvils from oxidation and graphitization, the entire cell is heated in a vacuum oven. The materials are chosen so that the pressure remains constant to within +-10% over the entire temperature range.
Germanium resistance thermometer calibration at superfluid helium temperatures

NASA Technical Reports Server (NTRS)

Mason, F. C.

1985-01-01

The rapid increase in resistance of high purity semi-conducting germanium with decreasing temperature in the superfluid helium range of temperatures makes this material highly adaptable as a very sensitive thermometer. Also, a germanium thermometer exhibits a highly reproducible resistance versus temperature characteristic curve upon cycling between liquid helium temperatures and room temperature. These two factors combine to make germanium thermometers ideally suited for measuring temperatures in many cryogenic studies at superfluid helium temperatures. One disadvantage, however, is the relatively high cost of calibrated germanium thermometers. In space helium cryogenic systems, many such thermometers are often required, leading to a high cost for calibrated thermometers. The construction of a thermometer calibration cryostat and probe which will allow for calibrating six germanium thermometers at one time, thus effecting substantial savings in the purchase of thermometers is considered.
Silicon Carbide-Based Hydrogen Gas Sensors for High-Temperature Applications

PubMed Central

Kim, Seongjeen; Choi, Jehoon; Jung, Minsoo; Joo, Sungjae; Kim, Sangchoel

2013-01-01

We investigated SiC-based hydrogen gas sensors with metal-insulator-semiconductor (MIS) structure for high temperature process monitoring and leak detection applications in fields such as the automotive, chemical and petroleum industries. In this work, a thin tantalum oxide (Ta2O5) layer was exploited with the purpose of sensitivity improvement, because tantalum oxide has good stability at high temperature with high permeability for hydrogen gas. Silicon carbide (SiC) was used as a substrate for high-temperature applications. We fabricated Pd/Ta2O5/SiC-based hydrogen gas sensors, and the dependence of their I-V characteristics and capacitance response properties on hydrogen concentrations were analyzed in the temperature range from room temperature to 500 °C. According to the results, our sensor shows promising performance for hydrogen gas detection at high temperatures. PMID:24113685
Silicon carbide-based hydrogen gas sensors for high-temperature applications.

PubMed

Kim, Seongjeen; Choi, Jehoon; Jung, Minsoo; Joo, Sungjae; Kim, Sangchoel

2013-10-09

We investigated SiC-based hydrogen gas sensors with metal-insulator-semiconductor (MIS) structure for high temperature process monitoring and leak detection applications in fields such as the automotive, chemical and petroleum industries. In this work, a thin tantalum oxide (Ta2O5) layer was exploited with the purpose of sensitivity improvement, because tantalum oxide has good stability at high temperature with high permeability for hydrogen gas. Silicon carbide (SiC) was used as a substrate for high-temperature applications. We fabricated Pd/Ta2O5/SiC-based hydrogen gas sensors, and the dependence of their I-V characteristics and capacitance response properties on hydrogen concentrations were analyzed in the temperature range from room temperature to 500 °C. According to the results, our sensor shows promising performance for hydrogen gas detection at high temperatures.
Thermodynamics and Transport Phenomena in High Temperature Steam Electrolysis Cells

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

James E. O'Brien

2012-03-01

Hydrogen can be produced from water splitting with relatively high efficiency using high temperature electrolysis. This technology makes use of solid-oxide cells, running in the electrolysis mode to produce hydrogen from steam, while consuming electricity and high temperature process heat. The overall thermal-to-hydrogen efficiency for high temperature electrolysis can be as high as 50%, which is about double the overall efficiency of conventional low-temperature electrolysis. Current large-scale hydrogen production is based almost exclusively on steam reforming of methane, a method that consumes a precious fossil fuel while emitting carbon dioxide to the atmosphere. An overview of high temperature electrolysis technologymore » will be presented, including basic thermodynamics, experimental methods, heat and mass transfer phenomena, and computational fluid dynamics modeling.« less
Des-acyl ghrelin prevents heatstroke-like symptoms in rats exposed to high temperature and high humidity.

PubMed

Inoue, Yoshiyuki; Hayashi, Yujiro; Kangawa, Kenji; Suzuki, Yoshihiro; Murakami, Noboru; Nakahara, Keiko

2016-02-26

We have shown previously that des-acyl ghrelin decreases body temperature in rats through activation of the parasympathetic nervous system. Here we investigated whether des-acyl ghrelin ameliorates heatstroke in rats exposed to high temperature. Peripheral administration of des-acyl ghrelin significantly attenuated hyperthermia induced by exposure to high-temperature (35°C) together with high humidity (70-80%). Although biochemical analysis revealed that exposure to high temperature significantly increased hematocrit and the serum levels of aspartate amino transferase (AST), alanine transaminase (ALT), blood urea nitrogen (BUN), creatinine and electrolytes (Na(+), K(+), Cl(-)), most of these heatstroke-associated reactions were significantly reduced by treatment with des-acyl ghrelin. The level of des-acyl ghrelin in plasma was also found to be significantly increased under high-temperature conditions. These results suggest that des-acyl ghrelin could be useful for preventing heatstroke under high temperature condition. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.
Suppression of OsMADS7 in rice endosperm stabilizes amylose content under high temperature stress.

PubMed

Zhang, Hua; Xu, Heng; Feng, Mengjie; Zhu, Ying

2018-01-01

High temperature significantly alters the amylose content of rice, resulting in mature grains with poor eating quality. However, only few genes and/or quantitative trait loci involved in this process have been isolated and the molecular mechanisms of this effect remain unclear. Here, we describe a floral organ identity gene, OsMADS7, involved in stabilizing rice amylose content at high temperature. OsMADS7 is greatly induced by high temperature at the early filling stage. Constitutive suppression of OsMADS7 stabilizes amylose content under high temperature stress but results in low spikelet fertility. However, rice plants with both stable amylose content at high temperature and normal spikelet fertility can be obtained by specifically suppressing OsMADS7 in endosperm. GBSSI is the major enzyme responsible for amylose biosynthesis. A low filling rate and high expression of GBSSI were detected in OsMADS7 RNAi plants at high temperature, which may be correlated with stabilized amylose content in these transgenic seeds under high temperature. Thus, specific suppression of OsMADS7 in endosperm could improve the stability of rice amylose content at high temperature, and such transgenic materials may be a valuable genetic resource for breeding rice with elite thermal resilience. © 2017 The Authors. Plant Biotechnology Journal published by Society for Experimental Biology and The Association of Applied Biologists and John Wiley & Sons Ltd.
Transcriptomic study to understand thermal adaptation in a high temperature-tolerant strain of Pyropia haitanensis

PubMed Central

Wang, Wenlei; Teng, Fei; Lin, Yinghui; Ji, Dehua; Xu, Yan; Chen, Changsheng

2018-01-01

Pyropia haitanensis, a high-yield commercial seaweed in China, is currently undergoing increasing levels of high-temperature stress due to gradual global warming. The mechanisms of plant responses to high temperature stress vary with not only plant type but also the degree and duration of high temperature. To understand the mechanism underlying thermal tolerance in P. haitanensis, gene expression and regulation in response to short- and long-term temperature stresses (SHS and LHS) was investigated by performing genome-wide high-throughput transcriptomic sequencing for a high temperature tolerant strain (HTT). A total of 14,164 differential expression genes were identified to be high temperature-responsive in at least one time point by high-temperature treatment, representing 41.10% of the total number of unigenes. The present data indicated a decrease in the photosynthetic and energy metabolic rates in HTT to reduce unnecessary energy consumption, which in turn facilitated in the rapid establishment of acclimatory homeostasis in its transcriptome during SHS. On the other hand, an increase in energy consumption and antioxidant substance activity was observed with LHS, which apparently facilitates in the development of resistance against severe oxidative stress. Meanwhile, ubiquitin-mediated proteolysis, brassinosteroids, and heat shock proteins also play a vital role in HTT. The effects of SHS and LHS on the mechanism of HTT to resist heat stress were relatively different. The findings may facilitate further studies on gene discovery and the molecular mechanisms underlying high-temperature tolerance in P. haitanensis, as well as allow improvement of breeding schemes for high temperature-tolerant macroalgae that can resist global warming. PMID:29694388
Transcriptomic study to understand thermal adaptation in a high temperature-tolerant strain of Pyropia haitanensis.

PubMed

Wang, Wenlei; Teng, Fei; Lin, Yinghui; Ji, Dehua; Xu, Yan; Chen, Changsheng; Xie, Chaotian

2018-01-01

Pyropia haitanensis, a high-yield commercial seaweed in China, is currently undergoing increasing levels of high-temperature stress due to gradual global warming. The mechanisms of plant responses to high temperature stress vary with not only plant type but also the degree and duration of high temperature. To understand the mechanism underlying thermal tolerance in P. haitanensis, gene expression and regulation in response to short- and long-term temperature stresses (SHS and LHS) was investigated by performing genome-wide high-throughput transcriptomic sequencing for a high temperature tolerant strain (HTT). A total of 14,164 differential expression genes were identified to be high temperature-responsive in at least one time point by high-temperature treatment, representing 41.10% of the total number of unigenes. The present data indicated a decrease in the photosynthetic and energy metabolic rates in HTT to reduce unnecessary energy consumption, which in turn facilitated in the rapid establishment of acclimatory homeostasis in its transcriptome during SHS. On the other hand, an increase in energy consumption and antioxidant substance activity was observed with LHS, which apparently facilitates in the development of resistance against severe oxidative stress. Meanwhile, ubiquitin-mediated proteolysis, brassinosteroids, and heat shock proteins also play a vital role in HTT. The effects of SHS and LHS on the mechanism of HTT to resist heat stress were relatively different. The findings may facilitate further studies on gene discovery and the molecular mechanisms underlying high-temperature tolerance in P. haitanensis, as well as allow improvement of breeding schemes for high temperature-tolerant macroalgae that can resist global warming.
The effects of gender on circadian rhythm of human physiological indexes in high temperature environment

NASA Astrophysics Data System (ADS)

Zheng, G. Z.; Li, K.; Bu, W. T.; Lu, Y. Z.; Wang, Y. J.

2018-03-01

In the context of frequent high temperature weather in recent years, peoples’ physical health is seriously threatened by the indoor high temperature. The physiological activities of human body show a certain changes of circadian rhythm. In this paper, the circadian rhythms of the physiological indexes in indoor high temperature environment were quantified and compared between the male subjects and female subjects. Ten subjects (five males and five females) were selected. The temperature conditions were set at 28°C, 32°C, 36°C and 38°C, respectively. The blood pressure, heart rate, rectal temperature, eardrum temperature, forehead temperature and mean skin temperature were measured for 24 hours continuously. The medians, amplitudes and acrophases of the circadian rhythms were obtained by the cosinor analysis method. Then the effects of gender on the circadian rhythm of the human body in high temperature environment were analyzed. The results indicate that, compared with the female subjects, the male medians of the systolic pressure and diastolic pressure were higher, and the male medians of heart rate and rectal temperature were lower, however, no significant differences were found between eardrum temperature, forehead temperature and mean skin temperature. This study can provide scientific basis for the health protection of the indoor relevant personnel.
High temperature deformation of NiAl and CoAl

NASA Technical Reports Server (NTRS)

Nix, W. D.

1982-01-01

The high temperature mechanical properties of the aluminides are reviewed with respect to their potential as high temperature structural materials. It is shown that NiAl and CoAl are substantially stronger than the pure metals Ni and Co at high temperatures and approach the strength of some superalloys, particularly when those superalloys are tested in "weak" directions. The factors that limit and control the high temperature strengths of NiAl and CoAl are examined to provide a basis for the development of intermetallic alloys of this type.
A high-temperature superconducting transformer with localized magnetic field

NASA Astrophysics Data System (ADS)

Volkov, E. P.; Dzhafarov, E. A.

2013-12-01

This paper describes a high-temperature superconducting transformer with a bar-type magnetic core and concentric windings with alternating layers, with single-channel and multi-channel arrangements. There is given the design concept of high-temperature superconducting windings of the transformer, made in the form of newly developed first-generation high-temperature superconducting ribbon wires, with localized magnetic field intended for producing maximum transport currents in the windings, as well as for reducing the consumption of a high-temperature superconducting material, cooling agent, and energy losses in these windings.
Copper Alloy For High-Temperature Uses

NASA Technical Reports Server (NTRS)

Dreshfield, Robert L.; Ellis, David L.; Michal, Gary

1994-01-01

Alloy of Cu/8Cr/4Nb (numbers indicate parts by atom percent) improved over older high-temperature copper-based alloys in that it offers enhanced high temperature strength, resistance to creep, and ductility while retaining most of thermal conductivity of pure copper; in addition, alloy does not become embrittled upon exposure to hydrogen at temperatures as high as 705 degrees C. Designed for use in presence of high heat fluxes and active cooling; for example, in heat exchangers in advanced aircraft and spacecraft engines, and other high-temperature applications in which there is need for such material. High conductivity and hardness of alloy exploited in welding electrodes and in high-voltage and high-current switches and other applications in which wear poses design problem.

High Temperature Ultrasonic Probe and Pulse-Echo Probe Mounting Fixture for Testing and Blind Alignment on Steam Pipes

NASA Technical Reports Server (NTRS)

Lih, Shyh-Shiuh (Inventor); Takano, Nobuyuki (Inventor); Lee, Hyeong Jae (Inventor); Bao, Xiaoqi (Inventor); Badescu, Mircea (Inventor); Bar-Cohen, Yoseph (Inventor); Sherrit, Stewart (Inventor); Ostlund, Patrick N. (Inventor)

2017-01-01

A high temperature ultrasonic probe and a mounting fixture for attaching and aligning the probe to a steam pipe using blind alignment. The high temperature ultrasonic probe includes a piezoelectric transducer having a high temperature. The probe provides both transmitting and receiving functionality. The mounting fixture allows the high temperature ultrasonic probe to be accurately aligned to the bottom external surface of the steam pipe so that the presence of liquid water in the steam pipe can be monitored. The mounting fixture with a mounted high temperature ultrasonic probe are used to conduct health monitoring of steam pipes and to track the height of condensed water through the wall in real-time.
High Ambient Temperature Represses Anthocyanin Biosynthesis through Degradation of HY5

PubMed Central

Kim, Sara; Hwang, Geonhee; Lee, Seulgi; Zhu, Jia-Ying; Paik, Inyup; Nguyen, Thom Thi; Kim, Jungmook; Oh, Eunkyoo

2017-01-01

Anthocyanins are flavonoid compounds that protect plant tissues from many environmental stresses including high light irradiance, freezing temperatures, and pathogen infection. Regulation of anthocyanin biosynthesis is intimately associated with environmental changes to enhance plant survival under stressful environmental conditions. Various factors, such as UV, visible light, cold, osmotic stress, and pathogen infection, can induce anthocyanin biosynthesis. In contrast, high temperatures are known to reduce anthocyanin accumulation in many plant species, even drastically in the skin of fruits such as grape berries and apples. However, the mechanisms by which high temperatures regulate anthocyanin biosynthesis in Arabidopsis thaliana remain largely unknown. Here, we show that high ambient temperatures repress anthocyanin biosynthesis through the E3 ubiquitin ligase CONSTITUTIVE PHOTOMORPHOGENIC1 (COP1) and the positive regulator of anthocyanin biosynthesis ELONGATED HYPOCOTYL5 (HY5). We show that an increase in ambient temperature decreases expression of genes required in both the early and late steps of the anthocyanin biosynthesis pathway in Arabidopsis seedlings. As a result, seedlings grown at a high temperature (28°C) accumulate less anthocyanin pigment than those grown at a low temperature (17°C). We further show that high temperature induces the degradation of the HY5 protein in a COP1 activity-dependent manner. In agreement with this finding, anthocyanin biosynthesis and accumulation do not respond to ambient temperature changes in cop1 and hy5 mutant plants. The degradation of HY5 derepresses the expression of MYBL2, which partially mediates the high temperature repression of anthocyanin biosynthesis. Overall, our study demonstrates that high ambient temperatures repress anthocyanin biosynthesis through a COP1-HY5 signaling module. PMID:29104579
Ultra-High Temperature Materials Characterization for Space and Missile Applications

NASA Technical Reports Server (NTRS)

Rogers, Jan; Hyers, Robert

2007-01-01

Numerous advanced space and missile technologies including propulsion systems require operations at high temperatures. Some very high-temperature materials are being developed to meet these needs, including refractory metal alloys, carbides, borides, and silicides. System design requires data for materials properties at operating temperatures. Materials property data are not available at the desired operating temperatures for many materials of interest. The objective of this work is to provide important physical property data at ultra-high temperatures. The MSFC Electrostatic Levitation (ESL) facility can provide measurements of thermophysical properties which include: creep strength, emissivity, density and thermal expansion. ESL uses electrostatic fields to position samples between electrodes during processing and characterization experiments. Samples float between the electrodes during studies and are free from any contact with a container or test apparatus. This provides a high purity environment for the study of high-temperature, reactive materials. ESL can be used to process a wide variety of materials including metals, alloys, ceramics, glasses and semiconductors. A system for the determination of total hemispherical emissivity is being developed for the MSFC ESL facility by AZ Technology Inc. The instrument has been designed to provide emissivity measurements for samples during ESL experiments over the temperature range 700-3400K. A novel non-contact technique for the determination of high-temperature creep strength has been developed. Data from selected ESL-based characterization studies will be presented. The ESL technique could advance space and missile technologies by advancing the knowledge base and the technology readiness level for ultra-high temperature materials. Applications include non-eroding nozzle materials and lightweight, high-temperature alloys for turbines and structures.
Friction Durability of Extremely Thin Diamond-Like Carbon Films at High Temperature

PubMed Central

Miyake, Shojiro; Suzuki, Shota; Miyake, Masatoshi

2017-01-01

To clarify the friction durability, both during and after the high-temperature heating of nanometer-thick diamond-like carbon (DLC) films, deposited using filtered cathodic vacuum arc (FCVA) and plasma chemical vapor deposition (P-CVD) methods, the dependence of the friction coefficient on the load and sliding cycles of the DLC films, were evaluated. Cluster-I consisted of a low friction area in which the DLC film was effective, while cluster-II consisted of a high friction area in which the lubricating effect of the DLC film was lost. The friction durability of the films was evaluated by statistical cluster analysis. Extremely thin FCVA-DLC films exhibited an excellent wear resistance at room temperature, but their friction durability was decreased at high temperatures. In contrast, the durability of the P-CVD-DLC films was increased at high temperatures when compared with that observed at room temperature. This inverse dependence on temperature corresponded to the nano-friction results obtained by atomic force microscopy. The decrease in the friction durability of the FCVA-DLC films at high temperatures, was caused by a complex effect of temperature and friction. The tribochemical reaction produced by the P-CVD-DLC films reduced their friction coefficient, increasing their durability at high temperatures. PMID:28772520
Friction Durability of Extremely Thin Diamond-Like Carbon Films at High Temperature.

PubMed

Miyake, Shojiro; Suzuki, Shota; Miyake, Masatoshi

2017-02-10

To clarify the friction durability, both during and after the high-temperature heating of nanometer-thick diamond-like carbon (DLC) films, deposited using filtered cathodic vacuum arc (FCVA) and plasma chemical vapor deposition (P-CVD) methods, the dependence of the friction coefficient on the load and sliding cycles of the DLC films, were evaluated. Cluster-I consisted of a low friction area in which the DLC film was effective, while cluster-II consisted of a high friction area in which the lubricating effect of the DLC film was lost. The friction durability of the films was evaluated by statistical cluster analysis. Extremely thin FCVA-DLC films exhibited an excellent wear resistance at room temperature, but their friction durability was decreased at high temperatures. In contrast, the durability of the P-CVD-DLC films was increased at high temperatures when compared with that observed at room temperature. This inverse dependence on temperature corresponded to the nano-friction results obtained by atomic force microscopy. The decrease in the friction durability of the FCVA-DLC films at high temperatures, was caused by a complex effect of temperature and friction. The tribochemical reaction produced by the P-CVD-DLC films reduced their friction coefficient, increasing their durability at high temperatures.
Data center thermal management

DOEpatents

Hamann, Hendrik F.; Li, Hongfei

2016-02-09

Historical high-spatial-resolution temperature data and dynamic temperature sensor measurement data may be used to predict temperature. A first formulation may be derived based on the historical high-spatial-resolution temperature data for determining a temperature at any point in 3-dimensional space. The dynamic temperature sensor measurement data may be calibrated based on the historical high-spatial-resolution temperature data at a corresponding historical time. Sensor temperature data at a plurality of sensor locations may be predicted for a future time based on the calibrated dynamic temperature sensor measurement data. A three-dimensional temperature spatial distribution associated with the future time may be generated based on the forecasted sensor temperature data and the first formulation. The three-dimensional temperature spatial distribution associated with the future time may be projected to a two-dimensional temperature distribution, and temperature in the future time for a selected space location may be forecasted dynamically based on said two-dimensional temperature distribution.
The stress relaxation of cement clinkers under high temperature

NASA Astrophysics Data System (ADS)

Wang, Xiufang; Bao, Yiwang; Liu, Xiaogen; Qiu, Yan

2015-12-01

The energy consumption of crushing is directly affected by the mechanical properties of cement materials. This research provides a theoretical proof for the mechanism of the stress relaxation of cement clinkers under high temperature. Compression stress relaxation under various high temperatures is discussed using a specially developed load cell, which can measure stress and displacement under high temperatures inside an autoclave. The cell shows that stress relaxation dramatically increases and that the remaining stress rapidly decreases with an increase in temperature. Mechanical experiments are conducted under various temperatures during the cooling process to study the changes in the grinding resistance of the cement clinker with temperature. The effects of high temperature on the load-displacement curve, compressive strength, and elastic modulus of cement clinkers are systematically studied. Results show that the hardening phenomenon of the clinker becomes apparent with a decrease in temperature and that post-peak behaviors manifest characteristics of the transformation from plasticity to brittleness. The elastic modulus and compressive strength of cement clinkers increase with a decrease in temperature. The elastic modulus increases greatly when the temperature is lower than 1000 °C. The compressive strength of clinkers increases by 73.4% when the temperature drops from 1100 to 800 °C.
The Effect of Acclimation to Sublethal Temperature on Subsequent Susceptibility of Sitophilus zeamais Mostchulsky (Coleoptera: Curculionidae) to High Temperatures

PubMed Central

Lü, Jianhua; Zhang, Huina

2016-01-01

Heat treatment is a popular alternative to synthetic pesticides in disinfesting food-processing facilities and empty grain storages. Sitophilus zeamais Mostchulsky is one of the most cosmopolitan and destructive insects found in empty grain storage facilities and processing facilities. The effect of acclimation in S. zeamais adults to sublethal high temperature on their subsequent susceptibility to high temperatures was investigated. S. zeamais adults were acclimated to 36°C for 0 (as a control), 1, 3, and 5 h, and then were exposed at 43, 47, 51, and 55°C for different time intervals respectively. Acclimation to sublethal high temperature significantly reduced subsequent susceptibility of S. zeamais adults to lethal high temperatures of 43, 47, 51, and 55°C, although the mortality of S. zeamais adults significantly increased with increasing exposure time at lethal high temperatures. The mortality of S. zeamais adults with 1, 3, and 5 h of acclimation to 36°C was significantly lower than that of S. zeamais adults without acclimation when exposed to the same lethal high temperatures. The present results suggest that the whole facility should be heated to target lethal high temperature as soon as possible, avoiding decreasing the control effectiveness of heat treatment due to the acclimation in stored product insects to sublethal temperature. PMID:27462906
Boron application improves yield of rice cultivars under high temperature stress during vegetative and reproductive stages.

PubMed

Shahid, Mohammad; Nayak, Amaresh Kumar; Tripathi, Rahul; Katara, Jawahar Lal; Bihari, Priyanka; Lal, Banwari; Gautam, Priyanka

2018-04-12

It is reported that high temperatures (HT) would cause a marked decrease in world rice production. In tropical regions, high temperatures are a constraint to rice production and the most damaging effect is on spikelet sterility. Boron (B) plays a very important role in the cell wall formation, sugar translocation, and reproduction of the rice crop and could play an important role in alleviating high temperature stress. A pot culture experiment was conducted to study the effect of B application on high temperature tolerance of rice cultivars in B-deficient soil. The treatments comprised of four boron application treatments viz. control (B0), soil application of 1 kg B ha -1 (B1), soil application of 2 kg B ha -1 (B2), and foliar spray of 0.2% B (Bfs); three rice cultivars viz. Annapurna (HT stress tolerant), Naveen, and Shatabdi (both HT stress susceptible); and three temperature regimes viz. ambient (AT), HT at vegetative stage (HTV), and HT at reproductive stage (HTR). The results revealed that high temperature stress during vegetative or flowering stage reduced grain yield of rice cultivars mainly because of low pollen viability and spikelet fertility. The effects of high temperature on the spikelet fertility and grain filling varied among cultivars and the growth stages of plant when exposed to the high temperature stress. Under high temperature stress, the tolerant cultivar displays higher cell membrane stability, less accumulation of osmolytes, more antioxidant enzyme activities, and higher pollen viability and spikelet fertility than the susceptible cultivars. In the present work, soil application of boron was effective in reducing the negative effects of high temperature both at vegetative and reproductive stages. Application of B results into higher grain yield under both ambient and high temperature condition over control for all the three cultivars; however, more increase was observed for the susceptible cultivar over the tolerant one. The results suggest that the exogenous application of boron had a substantial effect on cell membrane stability, sugar mobilization, pollen viability, and spikelet fertility, hence the yield. The cultivars due to their variation in the tolerance level for high temperature stress behaved differently, and at high temperature stress, more response of the application of boron was seen in susceptible cultivars.
Boron application improves yield of rice cultivars under high temperature stress during vegetative and reproductive stages

NASA Astrophysics Data System (ADS)

Shahid, Mohammad; Nayak, Amaresh Kumar; Tripathi, Rahul; Katara, Jawahar Lal; Bihari, Priyanka; Lal, Banwari; Gautam, Priyanka

2018-04-01

It is reported that high temperatures (HT) would cause a marked decrease in world rice production. In tropical regions, high temperatures are a constraint to rice production and the most damaging effect is on spikelet sterility. Boron (B) plays a very important role in the cell wall formation, sugar translocation, and reproduction of the rice crop and could play an important role in alleviating high temperature stress. A pot culture experiment was conducted to study the effect of B application on high temperature tolerance of rice cultivars in B-deficient soil. The treatments comprised of four boron application treatments viz. control (B0), soil application of 1 kg B ha-1 (B1), soil application of 2 kg B ha-1 (B2), and foliar spray of 0.2% B (Bfs); three rice cultivars viz. Annapurna (HT stress tolerant), Naveen, and Shatabdi (both HT stress susceptible); and three temperature regimes viz. ambient (AT), HT at vegetative stage (HTV), and HT at reproductive stage (HTR). The results revealed that high temperature stress during vegetative or flowering stage reduced grain yield of rice cultivars mainly because of low pollen viability and spikelet fertility. The effects of high temperature on the spikelet fertility and grain filling varied among cultivars and the growth stages of plant when exposed to the high temperature stress. Under high temperature stress, the tolerant cultivar displays higher cell membrane stability, less accumulation of osmolytes, more antioxidant enzyme activities, and higher pollen viability and spikelet fertility than the susceptible cultivars. In the present work, soil application of boron was effective in reducing the negative effects of high temperature both at vegetative and reproductive stages. Application of B results into higher grain yield under both ambient and high temperature condition over control for all the three cultivars; however, more increase was observed for the susceptible cultivar over the tolerant one. The results suggest that the exogenous application of boron had a substantial effect on cell membrane stability, sugar mobilization, pollen viability, and spikelet fertility, hence the yield. The cultivars due to their variation in the tolerance level for high temperature stress behaved differently, and at high temperature stress, more response of the application of boron was seen in susceptible cultivars.
High Work Output Ni-Ti-Pt High Temperature Shape Memory Alloys and Associated Processing Methods

NASA Technical Reports Server (NTRS)

Noebe, Ronald D. (Inventor); Draper, Susan L. (Inventor); Nathal, Michael V. (Inventor); Garg, Anita (Inventor)

2009-01-01

According to the invention, compositions of Ni-Ti-Pt high temperature, high force, shape memory alloys are disclosed that have transition temperatures above 100 C.; have narrow hysteresis; and produce a high specific work output.
Mechanical and Microstructure Study of Nickel-Based ODS Alloys Processed by Mechano-Chemical Bonding and Ball Milling

NASA Astrophysics Data System (ADS)

Amare, Belachew N.

Due to the need to increase the efficiency of modern power plants, land-based gas turbines are designed to operate at high temperature creating harsh environments for structural materials. The elevated turbine inlet temperature directly affects the materials at the hottest sections, which includes combustion chamber, blades, and vanes. Therefore, the hottest sections should satisfy a number of material requirements such as high creep strength, ductility at low temperature, high temperature oxidation and corrosion resistance. Such requirements are nowadays satisfied by implementing superalloys coated by high temperature thermal barrier coating (TBC) systems to protect from high operating temperature required to obtain an increased efficiency. Oxide dispersive strengthened (ODS) alloys are being considered due to their high temperature creep strength, good oxidation and corrosion resistance for high temperature applications in advanced power plants. These alloys operating at high temperature are subjected to different loading systems such as thermal, mechanical, and thermo-mechanical combined loads at operation. Thus, it is critical to study the high temperature mechanical and microstructure properties of such alloys for their structural integrity. The primary objective of this research work is to investigate the mechanical and microstructure properties of nickel-based ODS alloys produced by combined mechano-chemical bonding (MCB) and ball milling subjected to high temperature oxidation, which are expected to be applied for high temperature turbine coating with micro-channel cooling system. Stiffness response and microstructure evaluation of such alloy systems was studied along with their oxidation mechanism and structural integrity through thermal cyclic exposure. Another objective is to analyze the heat transfer of ODS alloy coatings with micro-channel cooling system using finite element analysis (FEA) to determine their feasibility as a stand-alone structural coating. During this project it was found that stiffness response to increase and remain stable to a certain level and reduce at latter stages of thermal cyclic exposure. The predominant growth and adherent Ni-rich outer oxide scale was found on top of the alumina scale throughout the oxidation cycles. The FEA analysis revealed that ODS alloys could be potential high temperature turbine coating materials if micro-channel cooling system is implemented.
DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Huizhen; Zhao, Dian; Cui, Yuangjing, E-mail: cuiyj@zju.edu.cn

Temperature measurements and thermal mapping using luminescent MOF operating in the high-temperature range are of great interest in the micro-electronic diagnosis. In this paper, we report a thermostable Eu/Tb-mixed MOF Eu{sub 0.37}Tb{sub 0.63}-BTC-a exhibiting strong luminescence at elevated temperature, which can serve as a ratiometric luminescent thermometer for high-temperature range. The high-temperature operating range (313–473 K), high relative sensitivity and accurate temperature resolution, make such a Eu/Tb-mixed MOF useful for micro-electronic diagnosis. - Graphical abstract: A thermostable Eu/Tb-mixed MOF Eu{sub 0.37}Tb{sub 0.63}-BTC-a was developed as a ratiometric luminescent thermometers in the high-temperature range of 313–473 K. - Highlights: • Amore » thermostable Eu/Tb-codoped MOF exhibiting strong luminescent at elevated temperature is reported. • The high-temperature operating range of Eu{sub 0.37}Tb{sub 0.63}-BTC-a is 313–473 K. • The mechanism of Eu{sub 0.37}Tb{sub 0.63}-BTC-a used as thermometers are also discussed.« less
Advanced high temperature heat flux sensors

NASA Technical Reports Server (NTRS)

Atkinson, W.; Hobart, H. F.; Strange, R. R.

1983-01-01

To fully characterize advanced high temperature heat flux sensors, calibration and testing is required at full engine temperature. This required the development of unique high temperature heat flux test facilities. These facilities were developed, are in place, and are being used for advanced heat flux sensor development.
Diamond anvil cell for spectroscopic investigation of materials at high temperature, high pressure and shear

DOEpatents

Westerfield, Curtis L.; Morris, John S.; Agnew, Stephen F.

1997-01-01

Diamond anvil cell for spectroscopic investigation of materials at high temperature, high pressure and shear. A cell is described which, in combination with Fourier transform IR spectroscopy, permits the spectroscopic investigation of boundary layers under conditions of high temperature, high pressure and shear.
Hyperscaling violating black hole solutions and magneto-thermoelectric DC conductivities in holography

NASA Astrophysics Data System (ADS)

Ge, Xian-Hui; Tian, Yu; Wu, Shang-Yu; Wu, Shao-Feng

2017-08-01

We derive new black hole solutions in Einstein-Maxwell-axion-dilaton theory with a hyperscaling violation exponent. We then examine the corresponding anomalous transport exhibited by cuprate strange metals in the normal phase of high-temperature superconductors via gauge-gravity duality. Linear-temperature-dependence resistivity and quadratic-temperature-dependence inverse Hall angle can be achieved. In the high-temperature regime, the heat conductivity and Hall Lorenz ratio are proportional to the temperature. The Nernst signal first increases as temperature goes up, but it then decreases with increasing temperature in the high-temperature regime.
High Temperature Resistant Organopolysiloxane Coating for Protecting and Repairing Rigid Thermal Insulation

NASA Technical Reports Server (NTRS)

Leiser, Daniel B. (Inventor); Hsu, Ming-Ta S. (Inventor); Chen, Timothy S. (Inventor)

1999-01-01

Ceramics are protected from high temperature degradation, including high temperature, oxidative, aeroconvective degradation by a high temperature and oxidation resistant coating of a room temperature curing, hydrolyzed and partially condensed liquid polyorganosiloxane to the surface of the ceramic. The liquid polyorganosiloxane is formed by the hydrolysis and partial condensation of an alkyltrialkoxysilane with water or a mixture of an alkyltrialkoxysilane and a dialkyldialkoxysilane with water. The liquid polyorganosiloxane cures at room temperature on the surface of the ceramic to form a hard, protective, solid coating which forms a high temperature environment, and is also used as an adhesive for adhering a repair plug in major damage to the ceramic. This has been found useful for protecting and repairing porous, rigid ceramics of a type used on reentry space vehicles.
High-temperature optical fiber sensors for characterization of advanced composite aerospace materials

NASA Astrophysics Data System (ADS)

Wavering, Thomas A.; Greene, Jonathan A.; Meller, Scott A.; Bailey, Timothy A.; Kozikowski, Carrie L.; Lenahan, Shannon M.; Murphy, Kent A.; Camden, Michael P.; Simmons, Larry W.

1999-01-01

Optical fiber sensors have numerous advantages over conventional sensing technologies. One such advantage is that optical fiber sensors can operate in high temperature environments. While most conventional electrical-based sensors do not operate reliably over 300 degrees C, fused silica based optical fiber sensors can survive up to 900 degrees C, and sapphire based optical fiber sensors can survive up to 2000 degrees C. Using both fused silica and sapphire technologies, we present result for high temperature strain, pressure, and temperature sensors using Extrinsic Fabry-Perot INterferometric-based and Bragg grating sensors. High temperature strain and temperature sensors were used to conduct fatigue testing of composite coupons at 600 degrees C. The results from these specific high temperature applications are presented along with future applications and directions for these sensors.
High-temperature effects on the light transmission through sapphire optical fiber

DOE PAGES

Wilson, Brandon A.; Petrie, Christian M.; Blue, Thomas E.

2018-03-13

Single crystal sapphire optical fiber was tested at high temperatures (1500°C) to determine its suitability for optical instrumentation in high-temperature environments. Broadband light transmission (450-2300 nm) through sapphire fiber was measured as a function of temperature as a test of the fiber's ability to survive and operate in high-temperature environments. Upon heating sapphire fiber to 1400°C, large amounts of light attenuation were measured across the entire range of light wavelengths that were tested. SEM and TEM images of the heated sapphire fiber indicated that a layer had formed at the surface of the fiber, most likely due to a chemicalmore » change at high temperatures. The microscopy results suggest that the surface layer may be in the form of aluminum hydroxide. Subsequent tests of sapphire fiber in an inert atmosphere showed minimal light attenuation at high temperatures along with the elimination of any surface layers on the fiber, indicating that the air atmosphere is indeed responsible for the increased attenuation and surface layer formation at high temperatures.« less
High-temperature effects on the light transmission through sapphire optical fiber

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

Wilson, Brandon A.; Petrie, Christian M.; Blue, Thomas E.

Single crystal sapphire optical fiber was tested at high temperatures (1500°C) to determine its suitability for optical instrumentation in high-temperature environments. Broadband light transmission (450-2300 nm) through sapphire fiber was measured as a function of temperature as a test of the fiber's ability to survive and operate in high-temperature environments. Upon heating sapphire fiber to 1400°C, large amounts of light attenuation were measured across the entire range of light wavelengths that were tested. SEM and TEM images of the heated sapphire fiber indicated that a layer had formed at the surface of the fiber, most likely due to a chemicalmore » change at high temperatures. The microscopy results suggest that the surface layer may be in the form of aluminum hydroxide. Subsequent tests of sapphire fiber in an inert atmosphere showed minimal light attenuation at high temperatures along with the elimination of any surface layers on the fiber, indicating that the air atmosphere is indeed responsible for the increased attenuation and surface layer formation at high temperatures.« less

High-Temperature Adhesives for Thermally Stable Aero-Assist Technologies

NASA Technical Reports Server (NTRS)

Eberts, Kenneth; Ou, Runqing

2013-01-01

Aero-assist technologies are used to control the velocity of exploration vehicles (EVs) when entering Earth or other planetary atmospheres. Since entry of EVs in planetary atmospheres results in significant heating, thermally stable aero-assist technologies are required to avoid the high heating rates while maintaining low mass. Polymer adhesives are used in aero-assist structures because of the need for high flexibility and good bonding between layers of polymer films or fabrics. However, current polymer adhesives cannot withstand temperatures above 400 C. This innovation utilizes nanotechnology capabilities to address this need, leading to the development of high-temperature adhesives that exhibit high thermal conductivity in addition to increased thermal decomposition temperature. Enhanced thermal conductivity will help to dissipate heat quickly and effectively to avoid temperature rising to harmful levels. This, together with increased thermal decomposition temperature, will enable the adhesives to sustain transient high-temperature conditions.
Evaluation of high temperature dielectric films for high voltage power electronic applications

NASA Technical Reports Server (NTRS)

Suthar, J. L.; Laghari, J. R.

1992-01-01

Three high temperature films, polyimide, Teflon perfluoroalkoxy and poly-P-xylene, were evaluated for possible use in high voltage power electronic applications, such as in high energy density capacitors, cables and microelectronic circuits. The dielectric properties, including permittivity and dielectric loss, were obtained in the frequency range of 50 Hz to 100 kHz at temperatures up to 200 C. The dielectric strengths at 60 Hz were determined as a function of temperature to 250 C. Confocal laser microscopy was performed to diagnose for voids and microimperfections within the film structure. The results obtained indicate that all films evaluated are capable of maintaining their high voltage properties, with minimal degradation, at temperatures up to 200 C. However, above 200 C, they lose some of their electrical properties. These films may therefore become viable candidates for high voltage power electronic applications at high temperatures.
Laser-machined microcavities for simultaneous measurement of high-temperature and high-pressure.

PubMed

Ran, Zengling; Liu, Shan; Liu, Qin; Huang, Ya; Bao, Haihong; Wang, Yanjun; Luo, Shucheng; Yang, Huiqin; Rao, Yunjiang

2014-08-07

Laser-machined microcavities for simultaneous measurement of high-temperature and high-pressure are demonstrated. These two cascaded microcavities are an air cavity and a composite cavity including a section of fiber and an air cavity. They are both placed into a pressure chamber inside a furnace to perform simultaneous pressure and high-temperature tests. The thermal and pressure coefficients of the short air cavity are ~0.0779 nm/°C and ~1.14 nm/MPa, respectively. The thermal and pressure coefficients of the composite cavity are ~32.3 nm/°C and ~24.4 nm/MPa, respectively. The sensor could be used to separate temperature and pressure due to their different thermal and pressure coefficients. The excellent feature of such a sensor head is that it can withstand high temperatures of up to 400 °C and achieve precise measurement of high-pressure under high temperature conditions.
Simulation of the real efficiencies of high-efficiency silicon solar cells

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

Sachenko, A. V., E-mail: sach@isp.kiev.ua; Skrebtii, A. I.; Korkishko, R. M.

The temperature dependences of the efficiency η of high-efficiency solar cells based on silicon are calculated. It is shown that the temperature coefficient of decreasing η with increasing temperature decreases as the surface recombination rate decreases. The photoconversion efficiency of high-efficiency silicon-based solar cells operating under natural (field) conditions is simulated. Their operating temperature is determined self-consistently by simultaneously solving the photocurrent, photovoltage, and energy-balance equations. Radiative and convective cooling mechanisms are taken into account. It is shown that the operating temperature of solar cells is higher than the ambient temperature even at very high convection coefficients (~300 W/m{sup 2}more » K). Accordingly, the photoconversion efficiency in this case is lower than when the temperature of the solar cells is equal to the ambient temperature. The calculated dependences for the open-circuit voltage and the photoconversion efficiency of high-quality silicon solar cells under concentrated illumination are discussed taking into account the actual temperature of the solar cells.« less
Exogenously Applied Plant Growth Regulators Enhance the Morpho-Physiological Growth and Yield of Rice under High Temperature.

PubMed

Fahad, Shah; Hussain, Saddam; Saud, Shah; Hassan, Shah; Ihsan, Zahid; Shah, Adnan N; Wu, Chao; Yousaf, Muhammad; Nasim, Wajid; Alharby, Hesham; Alghabari, Fahad; Huang, Jianliang

2016-01-01

A 2-year experiment was conducted to ascertain the effects of exogenously applied plant growth regulators (PGR) on rice growth and yield attributes under high day (HDT) and high night temperature (HNT). Two rice cultivars (IR-64 and Huanghuazhan) were subjected to temperature treatments in controlled growth chambers and four different combinations of ascorbic acid (Vc), alpha-tocopherol (Ve), brassinosteroids (Br), methyl jasmonates (MeJA), and triazoles (Tr) were applied. High temperature severely affected rice morphology, and also reduced leaf area, above-, and below-ground biomass, photosynthesis, and water use efficiency, while increased the leaf water potential of both rice cultivars. Grain yield and its related attributes except number of panicles, were reduced under high temperature. The HDT posed more negative effects on rice physiological attributes, while HNT was more detrimental for grain formation and yield. The Huanghuazhan performed better than IR-64 under high temperature stress with better growth and higher grain yield. Exogenous application of PGRs was helpful in alleviating the adverse effects of high temperature. Among PGR combinations, the Vc+Ve+MejA+Br was the most effective treatment for both cultivars under high temperature stress. The highest grain production by Vc+Ve+MejA+Br treated plants was due to enhanced photosynthesis, spikelet fertility and grain filling, which compensated the adversities of high temperature stress. Taken together, these results will be of worth for further understanding the adaptation and survival mechanisms of rice to high temperature and will assist in developing heat-resistant rice germplasm in future.
Generating high temperature tolerant transgenic plants: Achievements and challenges.

PubMed

Grover, Anil; Mittal, Dheeraj; Negi, Manisha; Lavania, Dhruv

2013-05-01

Production of plants tolerant to high temperature stress is of immense significance in the light of global warming and climate change. Plant cells respond to high temperature stress by re-programming their genetic machinery for survival and reproduction. High temperature tolerance in transgenic plants has largely been achieved either by over-expressing heat shock protein genes or by altering levels of heat shock factors that regulate expression of heat shock and non-heat shock genes. Apart from heat shock factors, over-expression of other trans-acting factors like DREB2A, bZIP28 and WRKY proteins has proven useful in imparting high temperature tolerance. Besides these, elevating the genetic levels of proteins involved in osmotic adjustment, reactive oxygen species removal, saturation of membrane-associated lipids, photosynthetic reactions, production of polyamines and protein biosynthesis process have yielded positive results in equipping transgenic plants with high temperature tolerance. Cyclic nucleotide gated calcium channel proteins that regulate calcium influxes across the cell membrane have recently been shown to be the key players in induction of high temperature tolerance. The involvement of calmodulins and kinases in activation of heat shock factors has been implicated as an important event in governing high temperature tolerance. Unfilled gaps limiting the production of high temperature tolerant transgenic plants for field level cultivation are discussed. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.
High temperature superconducting fault current limiter

DOEpatents

Hull, J.R.

1997-02-04

A fault current limiter for an electrical circuit is disclosed. The fault current limiter includes a high temperature superconductor in the electrical circuit. The high temperature superconductor is cooled below its critical temperature to maintain the superconducting electrical properties during operation as the fault current limiter. 15 figs.
High Temperature Silicon Carbide (SiC) Traction Motor Drive

DTIC Science & Technology

2011-08-09

UNCLASSIFIED Distribution Statement A. Approved for public release; distribution is unlimited. UNCLASSIFIED HIGH TEMPERATURE SILICON CARBIDE...be modular and conveniently distributed. Small component size and operation with high - temperature liquid coolant are essential factors in the...these densities, power modules capable of high - temperature operation were developed using SiC normally-off JFETs. This paper will discuss the unique
Conical Magnetic Bearing Development and Magnetic Bearing Testing for Extreme Temperature Environments

NASA Technical Reports Server (NTRS)

Keith, Theo G., Jr.; Jansen, Mark

2004-01-01

The main proposed research of this grant were: to design a high-temperature, conical magnetic bearing facility, to test the high-temperature, radial magnetic bearing facility to higher speeds, to investigate different backup bearing designs and materials, to retrofit the high-temperature test facility with a magnetic thrust bearing, to evaluate test bearings at various conditions, and test several lubricants using a spiral orbit tribometer. A high-temperature, conical magnetic bearing facility has been fully developed using Solidworks. The facility can reuse many of the parts of the current high-temperature, radial magnetic bearing, helping to reduce overall build costs. The facility has the ability to measure bearing force capacity in the X, Y, and Z directions through a novel bearing mounting design. The high temperature coils and laminations, a main component of the facility, are based upon the current radial design and can be fabricated at Texas A&M University. The coil design was highly successful in the radial magnetic bearing. Vendors were contacted about fabrication of the high temperature lamination stack. Stress analysis was done on the laminations. Some of the components were procured, but due to budget cuts, the facility build up was stopped.
Cycle analysis of planar SOFC power generation with serial connection of low and high temperature SOFCs

NASA Astrophysics Data System (ADS)

Araki, Takuto; Ohba, Takahiro; Takezawa, Shinya; Onda, Kazuo; Sakaki, Yoshinori

Solid oxide fuel cells (SOFCs) can be composed of solid components for stable operation, and high power generation efficiency is obtained by using high temperature exhaust heat for fuel reforming and bottoming power generation by a gas turbine. Recently, low-temperature SOFCs, which run in the temperature range of around 600 °C or above and give high power generation efficiency, have been developed. On the other hand, a power generation system with multi-staged fuel cells has been proposed by the United States DOE to obtain high efficiency. In our present study, a power generation system consisting of two-staged SOFCs with serial connection of low and high temperature SOFCs was investigated. Overpotential data for the low-temperature SOFC used in this study are based on recently published data, while data for high-temperature SOFC are based on our previous study. The numerical results show that the power generation efficiency of the two-staged SOFCs is 50.3% and the total efficiency of power generation with gas turbine is 56.1% under standard operating conditions. These efficiencies are a little higher than those by high-temperature SOFC only.
Silicon Carbide Nanotube Oxidation at High Temperatures

NASA Technical Reports Server (NTRS)

Ahlborg, Nadia; Zhu, Dongming

2012-01-01

Silicon Carbide Nanotubes (SiCNTs) have high mechanical strength and also have many potential functional applications. In this study, SiCNTs were investigated for use in strengthening high temperature silicate and oxide materials for high performance ceramic nanocomposites and environmental barrier coating bond coats. The high · temperature oxidation behavior of the nanotubes was of particular interest. The SiCNTs were synthesized by a direct reactive conversion process of multiwall carbon nanotubes and silicon at high temperature. Thermogravimetric analysis (TGA) was used to study the oxidation kinetics of SiCNTs at temperatures ranging from 800degC to1300degC. The specific oxidation mechanisms were also investigated.
High-temperature testing of glass/ceramic matrix composites

NASA Technical Reports Server (NTRS)

Mandell, John F.; Grande, Dodd H.; Dannemann, Kathryn A.

1989-01-01

Recent advances in ceramic and other high-temperature composites have created a need for test methods that can be used at 1000 C and above. Present test methods usually require adhesively bonded tabs that cannot be used at high temperatures. This paper discusses some of the difficulties with high-temperature test development and describes several promising test methods. Stress-strain data are given for Nicalon ceramic fiber reinforced glass and glass-ceramic matrix composites tested in air at temperatures up to 1000 C.
In Situ Observation of Gypsum-Anhydrite Transition at High Pressure and High Temperature

NASA Astrophysics Data System (ADS)

Liu, Chuan-Jiang; Zheng, Hai-Fei

2012-04-01

An in-situ Raman spectroscopic study of gypsum-anhydrite transition under a saturated water condition at high pressure and high temperature is performed using a hydrothermal diamond anvil cell (HDAC). The experimental results show that gypsum dissolvs in water at ambient temperature and above 496 MPa. With increasing temperature, the anhydrite (CaSO4) phase precipitates at 250-320°C in the pressure range of 1.0-1.5GPa, indicating that under a saturated water condition, both stable conditions of pressure and temperature and high levels of Ca and SO4 ion concentrations in aqueous solution are essential for the formation of anhydrite. A linear relationship between the pressure and temperature for the precipitation of anhydrite is established as P(GPa) = 0.0068T-0.7126 (250°C<=T<=320°C). Anhydrite remained stable during rapid cooling of the sample chamber, showing that the gypsum-anhydrite transition involving both dissolution and precipitation processes is irreversible at high pressure and high temperature.
Fabrication and modeling of bismuth titanate-PZT ceramic transducers for high temperature applications

NASA Astrophysics Data System (ADS)

Reinhardt, B.; Searfass, C.; Cyphers, R.; Sinding, K.; Pheil, C.; Tittmann, B.

2013-01-01

Utilization of a spray-on deposition technique of ferroelectric bismuth titanate (Bi4Ti3O12) composites has a competitive advantage to standard ultrasonic transducers. These can conform to curved surfaces, can operate at high temperature (Curie-Weiss temperature 685 °C) and are mechanically well-coupled to a substrate. However, an issue with many high temperature transducers such as bismuth titanate ceramics is that they have relatively low transduction efficiency, i.e. d33 is about 12-14 pC/F in Bi4Ti3O12 versus 650 pC/F in PZT-5H. It is a common conception that high-temperature capability comes at the cost of electro-mechanical coupling. It will be shown that the high temperature capability of bismuth-titanate-PZT composite transducers using the spray-on deposition technique previously developed, improves the electro-mechanical coupling while maintaining the high temperature performance and mechanical coupling. This material could provide advantages in harsh environments where high signal-to-noise ratios are needed.
Three-Dimensional Printable High-Temperature and High-Rate Heaters.

PubMed

Yao, Yonggang; Fu, Kun Kelvin; Yan, Chaoyi; Dai, Jiaqi; Chen, Yanan; Wang, Yibo; Zhang, Bilun; Hitz, Emily; Hu, Liangbing

2016-05-24

High temperature heaters are ubiquitously used in materials synthesis and device processing. In this work, we developed three-dimensional (3D) printed reduced graphene oxide (RGO)-based heaters to function as high-performance thermal supply with high temperature and ultrafast heating rate. Compared with other heating sources, such as furnace, laser, and infrared radiation, the 3D printed heaters demonstrated in this work have the following distinct advantages: (1) the RGO based heater can operate at high temperature up to 3000 K because of using the high temperature-sustainable carbon material; (2) the heater temperature can be ramped up and down with extremely fast rates, up to ∼20 000 K/second; (3) heaters with different shapes can be directly printed with small sizes and onto different substrates to enable heating anywhere. The 3D printable RGO heaters can be applied to a wide range of nanomanufacturing when precise temperature control in time, placement, and the ramping rate are important.
High skin temperature and hypohydration impair aerobic performance.

PubMed

Sawka, Michael N; Cheuvront, Samuel N; Kenefick, Robert W

2012-03-01

This paper reviews the roles of hot skin (>35°C) and body water deficits (>2% body mass; hypohydration) in impairing submaximal aerobic performance. Hot skin is associated with high skin blood flow requirements and hypohydration is associated with reduced cardiac filling, both of which act to reduce aerobic reserve. In euhydrated subjects, hot skin alone (with a modest core temperature elevation) impairs submaximal aerobic performance. Conversely, aerobic performance is sustained with core temperatures >40°C if skin temperatures are cool-warm when euhydrated. No study has demonstrated that high core temperature (∼40°C) alone, without coexisting hot skin, will impair aerobic performance. In hypohydrated subjects, aerobic performance begins to be impaired when skin temperatures exceed 27°C, and even warmer skin exacerbates the aerobic performance impairment (-1.5% for each 1°C skin temperature). We conclude that hot skin (high skin blood flow requirements from narrow skin temperature to core temperature gradients), not high core temperature, is the 'primary' factor impairing aerobic exercise performance when euhydrated and that hypohydration exacerbates this effect.
Evidence for a high temperature differentiation in a molten earth: A preliminary appraisal

NASA Technical Reports Server (NTRS)

Murthy, V. Rama

1992-01-01

If the earth were molten during its later stages of accretion as indicated by the present understanding of planetary accretion process, the differentiation that led to the formation of the core and mantle must have occurred at high temperatures in the range of 3000-5000 K because of the effect of pressure on the temperature of melting in the interior of the earth. This calls into question the use of low-temperature laboratory measurements of partition coefficients of trace elements to make inferences about earth accretion and differentiation. The low temperature partition coefficients cannot be directly applied to high temperature fractionations because partition coefficients refer to an equilibrium specific to a temperature for a given reaction, and must change in some proportion to exp 1/RT. There are no laboratory data on partition coefficients at the high temperatures relevant to differentiation in the interior of the earth, and an attempt to estimate high temperature distribution coefficients of siderophile elements was made by considering the chemical potential of a given element at equilibrium and how this potential changes with temperature, under some specific assumptions.
Development of high temperature acoustic emission sensing system using fiber Bragg grating

NASA Astrophysics Data System (ADS)

Pang, Dandan; Sui, Qingmei; Wang, Ming; Guo, Dongmei; Sai, Yaozhang

2018-03-01

In some applications in structural health monitoring (SHM), the acoustic emission (AE) detection technology is used in the high temperature environment. In this paper, a high-temperature-resistant AE sensing system is developed based on the fiber Bragg grating (FBG) sensor. A novel high temperature FBG AE sensor is designed with a high signal-to-noise ratio (SNR) compared with the traditional FBG AE sensor. The output responses of the designed sensors with different sensing fiber lengths also are investigated both theoretically and experimentally. Excellent AE detection results are obtained using the proposed FBG AE sensing system over a temperature range from 25 ° to 200 °. The experimental results indicate that this FBG AE sensing system can well meet the application requirement in AE detecting areas at high temperature.
Safe and Durable High-Temperature Lithium-Sulfur Batteries via Molecular Layer Deposited Coating.

PubMed

Li, Xia; Lushington, Andrew; Sun, Qian; Xiao, Wei; Liu, Jian; Wang, Biqiong; Ye, Yifan; Nie, Kaiqi; Hu, Yongfeng; Xiao, Qunfeng; Li, Ruying; Guo, Jinghua; Sham, Tsun-Kong; Sun, Xueliang

2016-06-08

Lithium-sulfur (Li-S) battery is a promising high energy storage candidate in electric vehicles. However, the commonly employed ether based electrolyte does not enable to realize safe high-temperature Li-S batteries due to the low boiling and flash temperatures. Traditional carbonate based electrolyte obtains safe physical properties at high temperature but does not complete reversible electrochemical reaction for most Li-S batteries. Here we realize safe high temperature Li-S batteries on universal carbon-sulfur electrodes by molecular layer deposited (MLD) alucone coating. Sulfur cathodes with MLD coating complete the reversible electrochemical process in carbonate electrolyte and exhibit a safe and ultrastable cycle life at high temperature, which promise practicable Li-S batteries for electric vehicles and other large-scale energy storage systems.
Torsional ultrasonic wave based level measurement system

DOEpatents

Holcomb, David E [Oak Ridge, TN; Kisner, Roger A [Knoxville, TN

2012-07-10

A level measurement system suitable for use in a high temperature and pressure environment to measure the level of coolant fluid within the environment, the system including a volume of coolant fluid located in a coolant region of the high temperature and pressure environment and having a level therein; an ultrasonic waveguide blade that is positioned within the desired coolant region of the high temperature and pressure environment; a magnetostrictive electrical assembly located within the high temperature and pressure environment and configured to operate in the environment and cooperate with the waveguide blade to launch and receive ultrasonic waves; and an external signal processing system located outside of the high temperature and pressure environment and configured for communicating with the electrical assembly located within the high temperature and pressure environment.

Effect of high environmental temperature on semen parameters among fertile men.

PubMed

Momen, M Nabil; Ananian, Fredrick B; Fahmy, Ibrahim M; Mostafa, Taymour

2010-04-01

To evaluate the effect of high environmental occupational temperature on semen parameters of fertile men. Prospective. Steel-casting plant. Ninety fertile workers exposed to a high temperature compared with 40 fertile workers working under ordinary conditions as control subjects. Measurement of scrotal temperature by invagination thermometry, air temperature, relative humidity by aspirated psychrometer, radiant heat by globe thermometer, air velocity by light vane anemometer, and semen analysis. Scrotal temperature and semen analysis. Nonsignificant difference was found between the two groups regarding their scrotal temperature. Also, nonsignificant differences were demonstrated regarding semen analysis parameters being in the normozoospermic range. Under high environmental temperature, semen parameters were within normozoospermic levels owing to body acclimatization mechanisms. Copyright 2010 American Society for Reproductive Medicine. Published by Elsevier Inc. All rights reserved.
High temperature enhances the ability of Trichoderma asperellum to infect Pleurotus ostreatus mycelia

PubMed Central

Qiu, Zhiheng; Wu, Xiangli; Zhang, Jinxia

2017-01-01

Trichoderma asperellum is one of the species which can be isolated from contaminated Pleurotus ostreatus cultivation substrate with green mold disease. This study focused on the relationship between high temperature and infectivity of T. asperellum to P. ostreatus. Antagonism experiments between T. asperellum and P. ostreatus mycelia revealed that high temperature-treated P. ostreatus mycelia were more easily infected by T. asperellum and covered by conidia. Microscopic observation also showed that P. ostreatus mycelia treated with high temperature could adsorb more T. asperellum conidia. Furthermore, conidia obtained from T. asperellum mycelia grown at 36°C featured higher germination rate compared with that incubated at 28°C. High temperature-treated T. asperellum mycelia can produce conidia in shorter periods, and T. asperellum mycelia were less sensitive to high temperature than P. ostreatus. Deactivated P. ostreatus mycelia can induce T. asperellum cell wall-degrading enzymes (CWDEs) and P. ostreatus mycelia subjected to high temperature showed induced CWDEs more effective than those incubated at 28°C. Moreover, T. asperellum showed higher CWDEs activity at high temperature. In dual cultures, hydrogen peroxide (H2O2) increased after 36°C, and high concentration of H2O2 could significantly inhibit the growth of P. ostreatus mycelia. In summary, our findings indicated for the first time that high temperature can induce a series of mechanisms to enhance infection abilities of T. asperellum to P. ostreatus mycelia and to cause Pleurotus green mold disease. PMID:29073211
High temperature enhances the ability of Trichoderma asperellum to infect Pleurotus ostreatus mycelia.

PubMed

Qiu, Zhiheng; Wu, Xiangli; Zhang, Jinxia; Huang, Chenyang

2017-01-01

Trichoderma asperellum is one of the species which can be isolated from contaminated Pleurotus ostreatus cultivation substrate with green mold disease. This study focused on the relationship between high temperature and infectivity of T. asperellum to P. ostreatus. Antagonism experiments between T. asperellum and P. ostreatus mycelia revealed that high temperature-treated P. ostreatus mycelia were more easily infected by T. asperellum and covered by conidia. Microscopic observation also showed that P. ostreatus mycelia treated with high temperature could adsorb more T. asperellum conidia. Furthermore, conidia obtained from T. asperellum mycelia grown at 36°C featured higher germination rate compared with that incubated at 28°C. High temperature-treated T. asperellum mycelia can produce conidia in shorter periods, and T. asperellum mycelia were less sensitive to high temperature than P. ostreatus. Deactivated P. ostreatus mycelia can induce T. asperellum cell wall-degrading enzymes (CWDEs) and P. ostreatus mycelia subjected to high temperature showed induced CWDEs more effective than those incubated at 28°C. Moreover, T. asperellum showed higher CWDEs activity at high temperature. In dual cultures, hydrogen peroxide (H2O2) increased after 36°C, and high concentration of H2O2 could significantly inhibit the growth of P. ostreatus mycelia. In summary, our findings indicated for the first time that high temperature can induce a series of mechanisms to enhance infection abilities of T. asperellum to P. ostreatus mycelia and to cause Pleurotus green mold disease.
High temperature superconducting fault current limiter

DOEpatents

Hull, John R.

1997-01-01

A fault current limiter (10) for an electrical circuit (14). The fault current limiter (10) includes a high temperature superconductor (12) in the electrical circuit (14). The high temperature superconductor (12) is cooled below its critical temperature to maintain the superconducting electrical properties during operation as the fault current limiter (10).
Diamond anvil cell for spectroscopic investigation of materials at high temperature, high pressure and shear

DOEpatents

Westerfield, C.L.; Morris, J.S.; Agnew, S.F.

1997-01-14

Diamond anvil cell is described for spectroscopic investigation of materials at high temperature, high pressure and shear. A cell is described which, in combination with Fourier transform IR spectroscopy, permits the spectroscopic investigation of boundary layers under conditions of high temperature, high pressure and shear. 4 figs.
Fuel processor temperature monitoring and control

DOEpatents

Keskula, Donald H.; Doan, Tien M.; Clingerman, Bruce J.

2002-01-01

In one embodiment, the method of the invention monitors one or more of the following conditions: a relatively low temperature value of the gas stream; a relatively high temperature value of the gas stream; and a rate-of-change of monitored temperature. In a preferred embodiment, the rate of temperature change is monitored to prevent the occurrence of an unacceptably high or low temperature condition. Here, at least two temperatures of the recirculating gas stream are monitored over a period of time. The rate-of-change of temperature versus time is determined. Then the monitored rate-of-change of temperature is compared to a preselected rate-of-change of value. The monitoring of rate-of-change of temperature provides proactive means for preventing occurrence of an unacceptably high temperature in the catalytic reactor.
Development of High Temperature (3400F) and High Pressure (27,000 PSI) Gas Venting Process for Nitrogen Batch Heater

DTIC Science & Technology

2018-01-01

for Mach 14 possibly degrading seals ability to contain pressure due to exposure to high temperatures. A different solution for Mach 14 case will be...AEDC-TR-18-H-1 Development of High Temperature (3400°F) and High Pressure (27,000 PSI) Gas Venting Process for Nitrogen Batch...Development of High Temperature (3400°F) and High Pressure (27,000 PSI) Gas Venting Process for Nitrogen Batch Heater FA9101-10-D-0001-0010 5b. GRANT
Very high temperature chemistry: Science justification for containerless experimentation in space

NASA Technical Reports Server (NTRS)

Hofmeister, William H.; Nordine, Paul

1990-01-01

A summary is presented of the justification for application of containerless processing in space to high temperature science. Low earth orbit offers a gravitational environment that allows samples to be positioned in an experimental apparatus by very small forces. Well controlled experiments become possible on reactive materials at high temperatures in a reasonably quiescent state and without container contamination. This provides an opportunity to advance the science of high temperature chemistry that can only be realized with a commitment by NASA to provide advanced facilities for in-space containerless study of materials at very high temperature.
Epitaxial heterojunctions of oxide semiconductors and metals on high temperature superconductors

NASA Technical Reports Server (NTRS)

Vasquez, Richard P. (Inventor); Hunt, Brian D. (Inventor); Foote, Marc C. (Inventor)

1994-01-01

Epitaxial heterojunctions formed between high temperature superconductors and metallic or semiconducting oxide barrier layers are provided. Metallic perovskites such as LaTiO3, CaVO3, and SrVO3 are grown on electron-type high temperature superconductors such as Nd(1.85)Ce(0.15)CuO(4-x). Alternatively, transition metal bronzes of the form A(x)MO(3) are epitaxially grown on electron-type high temperature superconductors. Also, semiconducting oxides of perovskite-related crystal structures such as WO3 are grown on either hole-type or electron-type high temperature superconductors.
Electrolytes for Use in High Energy Lithium-Ion Batteries with Wide Operating Temperature Range

NASA Technical Reports Server (NTRS)

Smart, Marshall C.; Ratnakumar, B. V.; West, W. C.; Whitcanack, L. D.; Huang, C.; Soler, J.; Krause, F. C.

2011-01-01

Objectives of this work are: (1) Develop advanced Li -ion electrolytes that enable cell operation over a wide temperature range (i.e., -30 to +60C). (2) Improve the high temperature stability and lifetime characteristics of wide operating temperature electrolytes. (3) Improve the high voltage stability of these candidate electrolytes systems to enable operation up to 5V with high specific energy cathode materials. (4) Define the performance limitations at low and high temperature extremes, as well as, life limiting processes. (5) Demonstrate the performance of advanced electrolytes in large capacity prototype cells.
High-temperature sustainability of strong fiber Bragg gratings written into Sb-Ge-codoped photosensitive fiber: decay mechanisms involved during annealing.

PubMed

Shen, Yonghang; He, Jinglei; Sun, Tong; Grattan, Kenneth T V

2004-03-15

An antimony--germanium- (Sb--Ge-) codoped fiber specially designed for the fabrication of fiber Bragg gratings (FBGs) with high temperature sustainability has been developed. The photosensitivity and the high-temperature sustainability of FBGs that have been written into this fiber were tested. The results obtained showed that the FBG written into this fiber has a very high temperature sustainability of 900 degrees C. A decay mechanism that involves cation hopping is presented to explain the observed high temperature sustainability of the grating written into this fiber.
High-temperature-measuring device

DOEpatents

Not Available

1981-01-27

A temperature measuring device for very high design temperatures (to 2000/sup 0/C) is described. The device comprises a homogenous base structure preferably in the form of a sphere or cylinder. The base structure contains a large number of individual walled cells. The base structure has a decreasing coefficient of elasticity within the temperature range being monitored. A predetermined quantity of inert gas is confined within each cell. The cells are dimensonally stable at the normal working temperature of the device. Increases in gaseous pressure within the cells will permanently deform the cell walls at temperatures within the high temperature range to be measured. Such deformation can be correlated to temperature by calibrating similarly constructed devices under known time and temperature conditions.
High temperature measuring device

DOEpatents

Tokarz, Richard D.

1983-01-01

A temperature measuring device for very high design temperatures (to 2,000.degree. C.). The device comprises a homogenous base structure preferably in the form of a sphere or cylinder. The base structure contains a large number of individual walled cells. The base structure has a decreasing coefficient of elasticity within the temperature range being monitored. A predetermined quantity of inert gas is confined within each cell. The cells are dimensionally stable at the normal working temperature of the device. Increases in gaseous pressure within the cells will permanently deform the cell walls at temperatures within the high temperature range to be measured. Such deformation can be correlated to temperature by calibrating similarly constructed devices under known time and temperature conditions.
Proteomic changes in rice leaves grown under open field high temperature stress conditions.

PubMed

Das, Smruti; Krishnan, P; Mishra, Vagish; Kumar, Ritesh; Ramakrishnan, B; Singh, N K

2015-11-01

The interactive effect of temperature with other climatic and soil factors has profound influences on the growth and development of rice. The responses of rice to high temperatures under field conditions are more important than those under the controlled conditions. To understand the genes associated with high temperature stress response in general and tolerance in particular, the expression of all those genes associated with adaptation and tolerance in rice requires proteomic analysis. High temperature stress-tolerant cv. N22 was subjected to 28/18 °C (control) and 42/32 °C (high temperature stress) at flowering stage. The plants were grown in the field under the free air temperature increment condition. The proteomic changes in rice leaves due to high temperature stress were discussed. The proteomes of leaves had about 3000 protein spots, reproducibly detected on 2-dimensional electrophoretic gels with 573 proteins differentially expressed between the control and the high temperature treatments. Putative physiological functions suggested five categories such as growth (15.4%), heat shock proteins (7.7%), regulatory proteins (26.9%), redox homeostasis proteins (11.5%) and energy and metabolism (38.5%) related proteins. The results of the present study suggest that cv. N22, an agronomically recognized temperature tolerant rice cultivar copes with high temperature stress in a complex manner. Several functional proteins play important roles in its responses. The predicted climate change events necessitate more studies using this cultivar under different simulated ecological conditions to identify proteomic changes and the associated genes to be used as biomarkers and to gain a better understanding on the biochemical pathways involved in tolerance.
Influence of High Temperature Treatment on Mechanical Behavior of a Coarse-grained Marble

NASA Astrophysics Data System (ADS)

Rong, G.; Peng, J.; Jiang, M.

2017-12-01

High temperature has a significant influence on the physical and mechanical behavior of rocks. With increasing geotechnical engineering structures concerning with high temperature problems such as boreholes for oil or gas production, underground caverns for storage of radioactive waste, and deep wells for injection of carbon dioxides, etc., it is important to study the influence of temperature on the physical and mechanical properties of rocks. This paper experimentally investigates the triaxial compressive properties of a coarse-grained marble after exposure to different high temperatures. The rock specimens were first heated to a predetermined temperature (200, 400, and 600 oC) and then cooled down to room temperature. Triaxial compression tests on these heat-treated specimens subjected to different confining pressures (i.e., 0, 5, 10, 15, 20, 25, 30, 35, and 40 MPa) were then conducted. Triaxial compression tests on rock specimens with no heat treatment were also conducted for comparison. The results show that the high temperature treatment has a significant influence on the microstructure, porosity, P-wave velocity, stress-strain relation, strength and deformation parameters, and failure mode of the tested rock. As the treatment temperature gradually increases, the porosity slightly increases and the P-wave velocity dramatically decreases. Microscopic observation on thin sections reveals that many micro-cracks will be generated inside the rock specimen after high temperature treatment. The rock strength and Young's modulus show a decreasing trend with increase of the treatment temperature. The ductility of the rock is generally enhanced as the treatment temperature increases. In general, the high temperature treatment weakens the performance of the tested rock. Finally, a degradation parameter is defined and a strength degradation model is proposed to characterize the strength behavior of heat-treated rocks. The results in this study provide useful data for evaluation of rock properties in high temperature condition.
Encapsulation of High Temperature Phase Change Materials for Thermal Energy Storage

NASA Astrophysics Data System (ADS)

Nath, Rupa

Thermal energy storage is a major contributor to bridge the gap between energy demand (consumption) and energy production (supply) by concentrating solar power. The utilization of high latent heat storage capability of phase change materials is one of the keys to an efficient way to store thermal energy. However, some of the limitations of the existing technology are the high volumetric expansion and low thermal conductivity of phase change materials (PCMs), low energy density, low operation temperatures and high cost. The present work deals with encapsulated PCM system, which operates at temperatures above 500°C and takes advantage of the heat transfer modes at such high temperatures to overcome the aforementioned limitations of PCMs. Encapsulation with sodium silicate coating on preformed PCM pellets were investigated. A low cost, high temperature metal, carbon steel has been used as a capsule for PCMs with a melting point above 500° C. Sodium silicate and high temperature paints were used for oxidation protection of steel at high temperatures. The emissivity of the coatings to enhance heat transfer was investigated.
High and low temperatures have unequal reinforcing properties in Drosophila spatial learning.

PubMed

Zars, Melissa; Zars, Troy

2006-07-01

Small insects regulate their body temperature solely through behavior. Thus, sensing environmental temperature and implementing an appropriate behavioral strategy can be critical for survival. The fly Drosophila melanogaster prefers 24 degrees C, avoiding higher and lower temperatures when tested on a temperature gradient. Furthermore, temperatures above 24 degrees C have negative reinforcing properties. In contrast, we found that flies have a preference in operant learning experiments for a low-temperature-associated position rather than the 24 degrees C alternative in the heat-box. Two additional differences between high- and low-temperature reinforcement, i.e., temperatures above and below 24 degrees C, were found. Temperatures equally above and below 24 degrees C did not reinforce equally and only high temperatures supported increased memory performance with reversal conditioning. Finally, low- and high-temperature reinforced memories are similarly sensitive to two genetic mutations. Together these results indicate the qualitative meaning of temperatures below 24 degrees C depends on the dynamics of the temperatures encountered and that the reinforcing effects of these temperatures depend on at least some common genetic components. Conceptualizing these results using the Wolf-Heisenberg model of operant conditioning, we propose the maximum difference in experienced temperatures determines the magnitude of the reinforcement input to a conditioning circuit.
Hot spots of wheat yield decline with rising temperatures.

PubMed

Asseng, Senthold; Cammarano, Davide; Basso, Bruno; Chung, Uran; Alderman, Phillip D; Sonder, Kai; Reynolds, Matthew; Lobell, David B

2017-06-01

Many of the irrigated spring wheat regions in the world are also regions with high poverty. The impacts of temperature increase on wheat yield in regions of high poverty are uncertain. A grain yield-temperature response function combined with a quantification of model uncertainty was constructed using a multimodel ensemble from two key irrigated spring wheat areas (India and Sudan) and applied to all irrigated spring wheat regions in the world. Southern Indian and southern Pakistani wheat-growing regions with large yield reductions from increasing temperatures coincided with high poverty headcounts, indicating these areas as future food security 'hot spots'. The multimodel simulations produced a linear absolute decline of yields with increasing temperature, with uncertainty varying with reference temperature at a location. As a consequence of the linear absolute yield decline, the relative yield reductions are larger in low-yielding environments (e.g., high reference temperature areas in southern India, southern Pakistan and all Sudan wheat-growing regions) and farmers in these regions will be hit hardest by increasing temperatures. However, as absolute yield declines are about the same in low- and high-yielding regions, the contributed deficit to national production caused by increasing temperatures is higher in high-yielding environments (e.g., northern India) because these environments contribute more to national wheat production. Although Sudan could potentially grow more wheat if irrigation is available, grain yields would be low due to high reference temperatures, with future increases in temperature further limiting production. © 2016 John Wiley & Sons Ltd.
High-Temperature Electromechanical Characterization of AlN Single Crystals.

PubMed

Kim, Taeyang; Kim, Jinwook; Dalmau, Rafael; Schlesser, Raoul; Preble, Edward; Jiang, Xiaoning

2015-10-01

Hexagonal AlN is a non-ferroelectric material and does not have any phase transition up to its melting point (>2000°C), which indicates the potential use of AlN for high-temperature sensing. In this work, the elastic, dielectric, and piezoelectric constants of AlN single crystals were investigated at elevated temperatures up to 1000°C by the resonance method. We used resonators of five different modes to obtain a complete set of material constants of AlN single crystals. The electrical resistivity of AlN at elevated temperature (1000°C) was found to be greater than 5 × 10(10) Ω · cm. The resonance frequency of the resonators, which was mainly determined by the elastic compliances, decreased linearly with increasing temperature, and was characterized by a relatively low temperature coefficient of frequency, in the range of -20 to -36 ppm/°C. For all the investigated resonator modes, the elastic constants and the electromechanical coupling factors exhibited excellent temperature stability, with small variations over the full temperature range, <11.2% and <17%, respectively. Of particular significance is that due to the pyroelectricity of AlN, both the dielectric and the piezoelectric constants had high thermal resistivity even at extreme high temperature (1000°C). Therefore, high electrical resistivity, temperature independence of electromechanical properties, as well as high thermal resistivity of the elastic, dielectric, and piezoelectric properties, suggest that AlN single crystals are a promising candidate for high-temperature piezoelectric sensing applications.
High temperature induces apoptosis and oxidative stress in pufferfish (Takifugu obscurus) blood cells.

PubMed

Cheng, Chang-Hong; Yang, Fang-Fang; Liao, Shao-An; Miao, Yu-Tao; Ye, Chao-Xia; Wang, An-Li; Tan, Jia-Wen; Chen, Xiao-Yan

2015-10-01

Water temperature is an important environmental factor in aquaculture farming that affects the survival and growth of organisms. The change in culture water temperature may not only modify various chemical and biological processes but also affect the status of fish populations. In previous studies, high temperature induced apoptosis and oxidative stress. However, the precise mechanism and the pathways that are activated in fish are still unclear. In the present study, we investigated the effects of high temperature (34°C) on the induction of apoptosis and oxidative stress in pufferfish (Takifugu obscurus) blood cells. The data showed that high temperature exposure increased oxygen species (ROS), cytoplasmic free-Ca(2+) concentration and cell apoptosis. To test the apoptotic pathway, the expression pattern of some key apoptotic related genes including P53, Bax, caspase 9 and caspase 3 were examined. The results showed that acute high temperature stress induced up-regulation of these genes, suggesting that the p53-Bax pathway and the caspase-dependent apoptotic pathway could be involved in apoptosis induced by high temperature stress. Furthermore, the gene expression of antioxidant enzymes (Cu/Zn-SOD, Mn-SOD, CAT, GPx, and GR) and heat shock proteins (HSP90 and HSP70) in the blood cells were induced by high temperature stress. Taken together, our results showed that high temperature-induced oxidative stress may cause pufferfish blood cells apoptosis, and cooperatively activated p53-Bax and caspase-dependent apoptotic pathway. Copyright © 2015 Elsevier Ltd. All rights reserved.

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