Fluids Demonstrations: Trailing Vortices, Plateau Border, Angle of Repose, and Flow Instability

ERIC Educational Resources Information Center

Shakerin, Said

2018-01-01

Demonstrations of physics phenomena via relatively simple devices and toys have been around for a long time. Because of the pedagogical value of demonstrations, this journal and other periodicals have published papers on the subject of classroom demonstrations including those related to fluid mechanics. Four new, low-cost apparatuses that…

Influence of moisture content on physical properties of minor millets.

PubMed

Balasubramanian, S; Viswanathan, R

2010-06-01

Physical properties including 1000 kernel weight, bulk density, true density, porosity, angle of repose, coefficient of static friction, coefficient of internal friction and grain hardness were determined for foxtail millet, little millet, kodo millet, common millet, barnyard millet and finger millet in the moisture content range of 11.1 to 25% db. Thousand kernel weight increased from 2.3 to 6.1 g and angle of repose increased from 25.0 to 38.2°. Bulk density decreased from 868.1 to 477.1 kg/m(3) and true density from 1988.7 to 884.4 kg/m(3) for all minor millets when observed in the moisture range of 11.1 to 25%. Porosity decreased from 63.7 to 32.5%. Coefficient of static friction of minor millets against mild steel surface increased from 0.253 to 0.728 and coefficient of internal friction was in the range of 1.217 and 1.964 in the moisture range studied. Grain hardness decreased from 30.7 to 12.4 for all minor millets when moisture content was increased from 11.1 to 25% db.

Shape of scoria cones on Mars: Insights from numerical modeling of ballistic pathways

NASA Astrophysics Data System (ADS)

Brož, Petr; Čadek, Ondřej; Hauber, Ernst; Rossi, Angelo Pio

2014-11-01

Morphological observations of scoria cones on Mars show that their cross-sectional shapes are different from those on Earth. Due to lower gravity and atmospheric pressure on Mars, particles are spread over a larger area than on Earth. Hence, erupted volumes are typically not large enough for the flank slopes to attain the angle of repose, in contrast to Earth where this is common. The distribution of ejected material forming scoria cones on Mars, therefore, is ruled mainly by ballistic distribution and not by redistribution of flank material by avalanching after the static angle of repose is reached. As a consequence, the flank slopes of the Martian scoria cones do not reach the critical angle of repose in spite of a large volume of ejected material. Therefore, the topography of scoria cones on Mars is governed mainly by ballistic distribution of ejected particles and is not influenced by redistribution of flank material by avalanching. The growth of a scoria cone can be studied numerically by tracking the ballistic trajectories and tracing the cumulative deposition of repeatedly ejected particles. We apply this approach to a specific volcanic field, Ulysses Colles on Mars, and compare our numerical results with observations. The scoria cones in this region are not significantly affected by erosion and their morphological shape still preserves a record of physical conditions at the time of eruption. We demonstrate that the topography of these scoria cones can be rather well (with accuracy of ∼10 m) reproduced provided that the ejection velocities are a factor of ∼2 larger and the ejected particles are about ten times finer than typical on Earth, corresponding to a mean particle velocity of ∼92 m/s and a real particle size of about 4 mm. This finding is in agreement with previous theoretical works that argued for larger magma fragmentation and higher ejection velocities on Mars than on Earth due to lower gravity and different environmental conditions.

Method to blend separator powders

DOEpatents

Guidotti, Ronald A.; Andazola, Arthur H.; Reinhardt, Frederick W.

2007-12-04

A method for making a blended powder mixture, whereby two or more powders are mixed in a container with a liquid selected from nitrogen or short-chain alcohols, where at least one of the powders has an angle of repose greater than approximately 50 degrees. The method is useful in preparing blended powders of Li halides and MgO for use in the preparation of thermal battery separators.

Experimental analysis of tablet properties for discrete element modeling of an active coating process.

PubMed

Just, Sarah; Toschkoff, Gregor; Funke, Adrian; Djuric, Dejan; Scharrer, Georg; Khinast, Johannes; Knop, Klaus; Kleinebudde, Peter

2013-03-01

Coating of solid dosage forms is an important unit operation in the pharmaceutical industry. In recent years, numerical simulations of drug manufacturing processes have been gaining interest as process analytical technology tools. The discrete element method (DEM) in particular is suitable to model tablet-coating processes. For the development of accurate simulations, information on the material properties of the tablets is required. In this study, the mechanical parameters Young's modulus, coefficient of restitution (CoR), and coefficients of friction (CoF) of gastrointestinal therapeutic systems (GITS) and of active-coated GITS were measured experimentally. The dynamic angle of repose of these tablets in a drum coater was investigated to revise the CoF. The resulting values were used as input data in DEM simulations to compare simulation and experiment. A mean value of Young's modulus of 31.9 MPa was determined by the uniaxial compression test. The CoR was found to be 0.78. For both tablet-steel and tablet-tablet friction, active-coated GITS showed a higher CoF compared with GITS. According to the values of the dynamic angle of repose, the CoF was adjusted to obtain consistent tablet motion in the simulation and in the experiment. On the basis of this experimental characterization, mechanical parameters are integrated into DEM simulation programs to perform numerical analysis of coating processes.

Persisting roughness when deposition stops.

PubMed

Schwartz, Moshe; Edwards, S F

2004-12-01

Useful theories for growth of surfaces under random deposition of material have been developed by several authors. The simplest theory is that introduced by Edwards and Wilkinson (EW), which is linear and soluble. Its nonlinear generalization by Kardar, Parisi, and Zhang (KPZ) resulted in many subsequent studies. Yet both EW and KPZ theories contain an unphysical feature. When deposition of material is stopped, both theories predict that as time tends to infinity, the surface becomes flat. In fact, of course, the final surface is not flat, but simply has no gradients larger than the gradient related to the angle of repose. We modify the EW and KPZ theories to accommodate this feature and study the consequences for the simpler system which is a modification of the EW equation. In spite of the fact that the equation describing the evolution of the surface is not linear, we find that the steady state in the presence of noise is not very different in the long-wavelength limit from that of the linear EW equation. The situation is quite different from that of EW when deposition stops. Initially there is still some rearrangement of the surface, but that stops as everywhere on the surface the gradient is less than that related to the angle of repose. The most interesting feature observed after deposition stops is the emergence of history-dependent steady-state distributions.

Multiple-layer compression-coated tablets: formulation and humidity studies of novel chewable amoxicillin/clavulanate tablet formulations.

PubMed

Wardrop, J; Jaber, A B; Ayres, J W

1998-08-01

The purpose of this study was to produce novel multiple-layer, compression-coated, chewable tablet formulations containing amoxicillin trihydrate, and clavulanic acid as potassium clavulanate, and to test in vitro dissolution characteristics and the effect of humidity stability compared to Augmentin chewable tablets as a reference. Double- and triple-layer tablets were manufactured on a laboratory scale by multiple-layer dry compression, and dissolution profiles of both active ingredients were determined. Tablets were subjected to stability evaluation in laboratory-scale humidity tanks maintained at constant humidity. Assay of content was determined by HPLC or UV spectroscopy. Physical characteristics of the powder mixture, such as angle of repose, and of tablets for hardness and friability, were also determined. Chewable tablets showed similar dissolution profiles in vitro for both active ingredients, compared to the marketed reference, Augmentin. The stability of clavulanic acid, but not amoxicillin, was increased in the novel triple or bilayer formulation. The tablets showed suitable friability, hardness, and angle of repose for starting materials to suggest that industrial scale-up is feasible. This approach to formulation of drugs containing multiple or moisture-sensitive ingredients has been shown to increase the stability of the central core drug without changing the dissolution pattern of the active ingredients. This formulation is expected to be bioequivalent in vivo based on these in vitro results.

Repose time and cumulative moment magnitude: A new tool for forecasting eruptions?

USGS Publications Warehouse

Thelen, W.A.; Malone, S.D.; West, M.E.

2010-01-01

During earthquake swarms on active volcanoes, one of the primary challenges facing scientists is determining the likelihood of an eruption. Here we present the relation between repose time and the cumulative moment magnitude (CMM) as a tool to aid in differentiating between an eruption and a period of unrest. In several case studies, the CMM is lower at shorter repose times than it is at longer repose times. The relationship between repose time and CMM may be linear in log-log space, particularly at Mount St. Helens. We suggest that the volume and competence of the plug within the conduit drives the strength of the precursory CMM.

Gravity-driven dense granular flows

NASA Astrophysics Data System (ADS)

Ertas, Deniz

2002-03-01

Despite their importance in many areas of science and technology, the emergent physics of hard granular systems remain largely obscure, especially when the packing density approaches that of a jammed system. In particular, I will focus on the rheology of gravity-driven dense granular flows on an incline with a ``rough" bottom in two and three dimensions. We have conducted large-scale molecular dynamics simulations of spheres that interact through linear damped spring or Hertzian force laws with a Coulomb failure criterion(D. Ertaş) et al., Europhys. Lett. 56, 214 (2001); L.E. Silbert et al., Phys. Rev. E 64, 051302 (2001).. This flow geometry produces a constant density profile, and reproduces key features of such flows that have been observed experimentally(O. Pouliquen, Phys. Fluids 11), 542 (1999), such as an angle of repose that depends on flow thickness, steady-state solutions at varying heights for a given inclination angle, and the scaling of the mean particle velocity with pile height (< v > ∝ H^3/2). These successes prompted us to carefully examine the rheology in the interior of the pile by measuring the full stress and strain tensors, which are generally unavailable through experiments. The type of force law has little impact on the behavior of the system. The bulk rheology can be approximately described in terms of extensions of Chapman-Enskog theory to dense packings(L. Bocquet et al.), cond-mat/0112072. However, close to the angle of repose, this description fails near the free surface, which exhibits a rheology dominated by normal stress differences that are small in the bulk. This change in rheology can be qualitatively understood in terms of stress-bearing force networks that are continuously formed by ``gravitational inelastic collapse" and destroyed by the imposed strain.

Real-time determination of critical quality attributes using near-infrared spectroscopy: a contribution for Process Analytical Technology (PAT).

PubMed

Rosas, Juan G; Blanco, Marcel; González, Josep M; Alcalà, Manel

2012-08-15

Process Analytical Technology (PAT) is playing a central role in current regulations on pharmaceutical production processes. Proper understanding of all operations and variables connecting the raw materials to end products is one of the keys to ensuring quality of the products and continuous improvement in their production. Near infrared spectroscopy (NIRS) has been successfully used to develop faster and non-invasive quantitative methods for real-time predicting critical quality attributes (CQA) of pharmaceutical granulates (API content, pH, moisture, flowability, angle of repose and particle size). NIR spectra have been acquired from the bin blender after granulation process in a non-classified area without the need of sample withdrawal. The methodology used for data acquisition, calibration modelling and method application in this context is relatively inexpensive and can be easily implemented by most pharmaceutical laboratories. For this purpose, Partial Least-Squares (PLS) algorithm was used to calculate multivariate calibration models, that provided acceptable Root Mean Square Error of Predictions (RMSEP) values (RMSEP(API)=1.0 mg/g; RMSEP(pH)=0.1; RMSEP(Moisture)=0.1%; RMSEP(Flowability)=0.6 g/s; RMSEP(Angle of repose)=1.7° and RMSEP(Particle size)=2.5%) that allowed the application for routine analyses of production batches. The proposed method affords quality assessment of end products and the determination of important parameters with a view to understanding production processes used by the pharmaceutical industry. As shown here, the NIRS technique is a highly suitable tool for Process Analytical Technologies. Copyright © 2012 Elsevier B.V. All rights reserved.

A model for the geomorphic development of normal-fault facets

NASA Astrophysics Data System (ADS)

Tucker, G. E.; Hobley, D. E. J.; McCoy, S. W.

2014-12-01

Triangular facets are among the most striking landforms associated with normal faulting. The genesis of facets is of great interest both for the information facets contain about tectonic motion, and because the progressive emergence of facets makes them potential recorders of both geomorphic and tectonic history. In this report, we present observations of triangular facets in the western United States and in the Italian Central Apennines. Facets in these regions typically form quasi-planar surfaces that are aligned in series along and above the trace of an active fault. Some facet surfaces consist mainly of exposed bedrock, with a thin and highly discontinuous cover of loose regolith. Other facets are mantled by a several-decimeter-thick regolith cover. Over the course of its morphologic development, a facet slope segment may evolve from a steep (~60 degree) bedrock fault scarp, well above the angle of repose for soil, to a gentler (~20-40 degree) slope that can potentially sustain a coherent regolith cover. This evolutionary trajectory across the angle of repose renders nonlinear diffusion theory inapplicable. To formulate an alternative process-based theory for facet evolution, we use a particle-based approach that acknowledges the possibility for both short- and long-range sediment-grain motions, depending on the topography. The processes of rock weathering, grain entrainment, and grain motion are represented as stochastic state-pair transitions with specified transition rates. The model predicts that facet behavior can range smoothly along the spectrum from a weathering-limited mode to a transport-limited mode, depending on the ratio of fault-slip rate to bare-bedrock regolith production rate. The model also implies that facets formed along a fault with pinned tips should show systematic variation in slope angle that correlates with along-fault position and slip rate. Preliminary observations from central Italy and the eastern Basin and Range are consistent with this prediction.

Powder collection apparatus/method

DOEpatents

Anderson, I.E.; Terpstra, R.L.; Moore, J.A.

1994-01-11

Device for separating and collecting ultrafine atomized powder from the gas stream of a gas atomizing apparatus comprises a housing having an interior wall oriented at an angle relative to horizontal so as to form a downwardly converging, conical expansion chamber, an inlet conduit communicated to the expansion chamber proximate an upper region thereof for receiving the gas stream, and an outlet proximate a lower region of the expansion chamber. The inlet conduit is oriented at a compound inclined angle (with respect to horizontal) selected to promote separation and collection of powder from the gas stream in the expansion chamber. The compound angle comprises a first entrance angle that is greater than the angle of repose of the powder on the housing interior wall such that any powder accumulation in the inlet conduit tends to flow down the wall toward the outlet. The second angle is selected generally equal to the angle of the housing interior wall measured from the same horizontal plane so as to direct the gas stream into the expansion chamber generally tangent to the housing interior wall to establish a downward swirling gas stream flow in the expansion chamber. A powder collection container is communicated to the outlet of the expansion chamber to collect the powder for further processing. 4 figures.

Powder collection apparatus/method

DOEpatents

Anderson, Iver E.; Terpstra, Robert L.; Moore, Jeffery A.

1994-01-11

Device for separating and collecting ultrafine atomized powder from the gas stream of a gas atomizing apparatus comprises a housing having an interior wall oriented at an angle relative to horizontal so as to form a downwardly converging, conical expansion chamber, an inlet conduit communicated to the expansion chamber proximate an upper region thereof for receiving the gas stream, and an outlet proximate a lower region of the expansion chamber. The inlet conduit is oriented at a compound inclined angle (with respect to horizontal) selected to promote separation and collection of powder from the gas stream in the expansion chamber. The compound angle comprises a first entrance angle that is greater than the angle of repose of the powder on the housing interior wall such that any powder accumulation in the inlet conduit tends to flow down the wall toward the outlet. The second angle is selected generally equal to the angle of the housing interior wall measured from the same horizontal plane so as to direct the gas stream into the expansion chamber generally tangent to the housing interior wall to establish a downward swirling gas stream flow in the expansion chamber. A powder collection container is communicated to the outlet of the expansion chamber to collect the powder for further processing.

Limited-interval definitions of the photometric functions of lunar crater walls by photography from orbiting Apollo

USGS Publications Warehouse

Wildey, R.L.

1971-01-01

By the use of only relative photometry (intraframe) it is shown that the photometric functions of material reposed on the inner walls of some of the ypunger lunar craters photographed on the far side of the Moon from the Apollo 11 Command Module are not of a form which can be reduced to a dependence on phase angle and brightness-longitude (g, ??) alone. Some other dependence on the completely general degrees of freedom described by phase angle, angle of incidence, and angle of emergence (g, i, ??{lunate}) seems to be required. In addition, however, it has been found that a dependence of g and ?? is more closely approached for the crater, in the group observed, which is obviously the oldest by virtue of the roundedness of the rim crest and the mass-wasting which has occured on its inner walls. The possibility thus arises of crater age-dating by making a brightness ratio measurement together with some image geometry measurements. It is at least evident that more than one type of geologic material has been encountered. ?? 1971.

Mechanical properties of dust collected by dust separators in iron ore sinter plants.

PubMed

Lanzerstorfer, Christof

2015-01-01

The flow-related mechanical properties of dusts from the de-dusting systems of several sinter plants were investigated. The mass median diameters of the dusts were in the range from approximately 3 to 100 µm. Also, the bulk density of the dusts varied in a wide range (approximately 400 to 2300 kg/m³). A good correlation between the bulk density and the mass median diameter for most of the dusts was found. In contrast, the angles of repose did not vary very much, only for the coarsest dust a significantly lower value was measured. The angles of internal friction as well as the wall friction angles were lower for coarse dust and higher for fine dust. The shear tests showed that both angles depend considerably on the stress level. At low stress, the angles decreased significantly with increasing values of stress, whereas at higher stress, the dependence was small or even disappeared. The only exception to this behaviour was shown by the finest dust. The flowability decreased with the particle size. The flowability categories suggested by the three flowability indicators were passable only for the coarser dusts. For the finer dusts, the flowability was overestimated by all flowability indicators.

Rheology of surface granular flows

NASA Astrophysics Data System (ADS)

Orpe, Ashish V.; Khakhar, D. V.

Surface granular flow, comprising granular material flowing on the surface of a heap of the same material, occurs in several industrial and natural systems. The rheology of such a flow was investigated by means of measurements of velocity and number-density profiles in a quasi-two-dimensional rotating cylinder, half-filled with a model granular material monosize spherical stainless-steel particles. The measurements were made at the centre of the cylinder, where the flow is fully developed, using streakline photography and image analysis. The stress profile was computed from the number-density profile using a force balance which takes into account wall friction. Mean-velocity and root-mean-square (r.m.s.)-velocity profiles are reported for different particle sizes and cylinder rotation speeds. The profiles for the mean velocity superimpose when distance is scaled by the particle diameter d and velocity by a characteristic shear rate dot{gamma}_C = [gsin(beta_m-beta_s)/dcosbeta_s](1/2) and the particle diameter, where beta_m is the maximum dynamic angle of repose and beta_s is the static angle of repose. The maximum dynamic angle of repose is found to vary with the local flow rate. The scaling is also found to work for the r.m.s. velocity profiles. The mean velocity is found to decay exponentially with depth in the bed, with decay length lambda=1.1d. The r.m.s. velocity shows similar behaviour but with lambda=1.7d. The r.m.s. velocity profile shows two regimes: near the free surface the r.m.s. velocity is nearly constant and below a transition point it decays linearly with depth. The shear rate, obtained by numerical differentiation of the velocity profile, is not constant anywhere in the layer and has a maximum which occurs at the same depth as the transition in the r.m.s. velocity profile. Above the transition point the velocity distributions are Gaussian and below the transition point the velocity distributions gradually approach a Poisson distribution. The shear stress increases roughly linearly with depth. The variation in the apparent viscosity eta with r.m.s. velocity u shows a relatively sharp transition at the shear-rate maximum, and in the region below this point the apparent viscosity eta˜ u(-1.5) . The measurements indicate that the flow comprises two layers: an upper low-viscosity layer with a nearly constant r.m.s. velocity and a lower layer of increasing viscosity with a decreasing r.m.s. velocity. The thickness of the upper layer depends on the local flow rate and is independent of particle diameter while the reverse is found to hold for the lower-layer thickness. The experimental data is compared with the predictions of three models for granular flow.

Evaluation of geophysical properties of the lunar regolith for the design of precursor scientific missions for the space exploration initiative

NASA Technical Reports Server (NTRS)

Morgan, Paul

1990-01-01

The following topics are addressed: (1) the frequency of encountering boulders that represent hazards to lunar operations; (2) the ease of lunar soil excavation; (3) the use of explosives in excavation operation; (4) the trafficability of the regolith; (5) problems encountered in mining (probably strip mining) of the regolith; (6) the stable angle(s) of repose in excavation of the regolith; (7) the layering to be encountered in the subsurface; (8) knowledge of the regolith site and the possibility of its general application to any site on the lunar surface; (9) the data needed to characterize a site for a lunar base; (10) the influence of regolith properties on the design of geophysical experiments from the lunar base; and (11) terrestrial analogues for the geophysical properties of the lunar regolith.

Experimental confirmation of the atomic force microscope cantilever stiffness tilt correction

NASA Astrophysics Data System (ADS)

Gates, Richard S.

2017-12-01

The tilt angle (angle of repose) of an AFM cantilever relative to the surface it is interrogating affects the effective stiffness of the cantilever as it analyzes the surface. For typical AFMs and cantilevers that incline from 10° to 15° tilt, this is thought to be a 3%-7% stiffness increase correction. While the theoretical geometric analysis of this effect may have reached a consensus that it varies with cos-2 θ, there is very little experimental evidence to confirm this using AFM cantilevers. Recently, the laser Doppler vibrometry thermal calibration method utilized at NIST has demonstrated sufficient stiffness calibration accuracy, and precision to allow a definitive experimental confirmation of the particular trigonometric form of this tilt effect using a commercial microfabricated AFM cantilever specially modified to allow strongly tilted (up to 15°) effective cantilever stiffness measurements.

Evaluation of the tablets' surface flow velocities in pan coaters.

PubMed

Dreu, Rok; Toschkoff, Gregor; Funke, Adrian; Altmeyer, Andreas; Knop, Klaus; Khinast, Johannes; Kleinebudde, Peter

2016-09-01

The tablet pan coating process involves various types of transverse tablet bed motions, ranging from rolling to cascading. To preserve satisfactory results in terms of coating quality after scale-up, understanding the dynamics of pan coating process should be achieved. The aim of this study was to establish a methodology of estimating translational surface velocities of the tablets in a pan coater and to assess their dependence on the drum's filling degree, the pan speed, the presence of baffles and the selected tablet properties in a dry bed system and during coating while varying the drum's filling degree and the pan speed. Experiments were conducted on the laboratory scale and on the pilot scale in side-vented pan coaters. Surface movement of biconvex two-layer tablets was assessed before, during and after the process of active coating. In order to determine the tablets' surface flow velocities, a high-speed video of the tablet surface flow was recorded via a borescope inserted into the coating drum and analysed via a cross-correlation algorithm. The obtained tablet velocity data were arranged in a linear fashion as a function of the coating drum's radius and frequency. Velocity data obtained during coating were close to those of dry tablets after coating. The filling degree had little influence on the tablet velocity profile in a coating drum with baffles but clearly affected it in a coating drum without baffles. In most but not all cases, tablets with a lower static angle of repose had tablet velocity profiles with lower slopes than tablets with higher inter-tablet friction. This particular tablet velocity response can be explained by case specific values of tablet bed's dynamic angle of repose. Copyright © 2016 Elsevier B.V. All rights reserved.

Memory of the unjamming transition during cyclic tiltings of a granular pile.

PubMed

Deboeuf, S; Dauchot, O; Staron, L; Mangeney, A; Vilotte, J-P

2005-11-01

Discrete numerical simulations are performed to study the evolution of the microstructure and the response of a granular packing during successive loading-unloading cycles, consisting of quasistatic rotations in the gravity field between opposite inclination angles. We show that internal variables--e.g., stress and fabric of the pile--exhibit hysteresis during these cycles due to the exploration of different metastable configurations. Interestingly, the hysteretic behavior of the pile strongly depends on the maximal inclination of the cycles, giving evidence of the irreversible modifications of the pile state occurring close to the unjamming transition. More specifically, we show that for cycles with maximal inclination larger than the repose angle, the weak-contact network carries the memory of the unjamming transition. These results demonstrate the relevance of a two-phase description--strong- and weak-contact networks--for a granular system, as soon as it has approached the unjamming transition.

Flow, packing and compaction properties of novel coprocessed multifunctional directly compressible excipients prepared from tapioca starch and mannitol.

PubMed

Adeoye, Oluwatomide; Alebiowu, Gbenga

2014-12-01

Novel multifunctional excipients were prepared by coprocessing tapioca starch with mannitol using two methods viz; co-grinding and co-fusion. The flow, packing and compaction properties of the native and novel excipients were evaluated by using density, Hausner's ratio, angle of repose, the maximum volume reduction, consolidation index, the rate of consolidation, angle of internal friction, morphological properties, Heckel analysis, tensile strength and dilution potential as evaluation parameters. The study revealed that the method of coprocessing, particle size and particle shape influenced the properties of the resulting novel excipients. Co-grinding was less effective than co-fusion in the preparation of excipients with enhanced properties. The study concluded that coprocessing tapioca starch and mannitol will enhance the flow, packing and compaction properties of the novel excipient and that the co-fusion method of coprocessing would produce novel excipients with enhanced direct compression potential compared to the co-grinding method.

Mathematical modeling of the burden distribution in the blast furnace shaft

NASA Astrophysics Data System (ADS)

Park, Jong-In; Jung, Hun-Je; Jo, Min-Kyu; Oh, Han-Sang; Han, Jeong-Whan

2011-06-01

Process efficiency in the blast furnace is influenced by the gas flow pattern, which is dictated by the burden profile. Therefore, it is important to control the burden distribution so as to achieve reasonable gas flow in the blast furnace operation. Additionally, the charging pattern selection is important as it affects the burden trajectory and stock profile. For analysis of the burden distribution, a new analysis model was developed by use of the spreadsheet program, Microsoft® Office Excel, based on visual basic. This model is composed of the falling burden trajectory and a stock model. The burden trajectory is determined by the burden type, batch weight, rotating velocity of the chute, tilting angle, and friction coefficient. After falling, stock lines are formed by the angle of repose, which is affected by the burden trajectory and the falling velocity. The mathematical formulas for developing this model were modified by a scaled model experiment and DEM simulation.

Granular flows at recurring slope lineae on Mars indicate a limited role for liquid water

NASA Astrophysics Data System (ADS)

Dundas, Colin M.; McEwen, Alfred S.; Chojnacki, Matthew; Milazzo, Moses P.; Byrne, Shane; McElwaine, Jim N.; Urso, Anna

2017-12-01

Recent liquid water flow on Mars has been proposed based on geomorphological features, such as gullies. Recurring slope lineae — seasonal flows that are darker than their surroundings — are candidate locations for seeping liquid water on Mars today, but their formation mechanism remains unclear. Topographical analysis shows that the terminal slopes of recurring slope lineae match the stopping angle for granular flows of cohesionless sand in active Martian aeolian dunes. In Eos Chasma, linea lengths vary widely and are longer where there are more extensive angle-of-repose slopes, inconsistent with models for water sources. These observations suggest that recurring slope lineae are granular flows. The preference for warm seasons and the detection of hydrated salts are consistent with some role for water in their initiation. However, liquid water volumes may be small or zero, alleviating planetary protection concerns about habitable environments.

Granular flows at recurring slope lineae on Mars indicate a limited role for liquid water

USGS Publications Warehouse

Dundas, Colin M.; McEwen, Alfred S.; Chojnacki, Matthew; Milazzo, Moses; Byrne, Shane; McElwaine, Jim; Urso, Anna

2017-01-01

Recent liquid water flow on Mars has been proposed based on geomorphological features, such as gullies. Recurring slope lineae — seasonal flows that are darker than their surroundings — are candidate locations for seeping liquid water on Mars today, but their formation mechanism remains unclear. Topographical analysis shows that the terminal slopes of recurring slope lineae match the stopping angle for granular flows of cohesionless sand in active Martian aeolian dunes. In Eos Chasma, linea lengths vary widely and are longer where there are more extensive angle-of-repose slopes, inconsistent with models for water sources. These observations suggest that recurring slope lineae are granular flows. The preference for warm seasons and the detection of hydrated salts are consistent with some role for water in their initiation. However, liquid water volumes may be small or zero, alleviating planetary protection concerns about habitable environments.

Decision Rules for Pictorial Threat Classification

DTIC Science & Technology

2009-07-01

utilise un seul indice pour classifier des cibles, et la stratégie de classification bayesienne qui repose sur des modèles de statistiques...L’approche heuristique consistant à « ne garder que le meilleur en vue de la classification » (TTB-C) repose sur l’hypothèse qu’un seul repère, hautement...stratégie bayesienne repose sur le recrutement de mécanismes perceptuels automatiques, elle peut s’avérer plus profitable dans des situations où

[Impact of directly compressed auxiliary materials on powder property of fermented cordyceps powder].

PubMed

Chen, Li-Hua; Yue, Guo-Chao; Guan, Yong-Mei; Yang, Ming; Zhu, Wei-Feng

2014-01-01

To investigate such physical indexes as hygroscopicity, angle of repose, bulk density, fillibility of compression of mixed powder of directly compressed auxiliary materials and fermented cordyceps powder by using micromeritic study methods. The results showed that spray-dried lactose Flowlac100 and microcrystalline cellulose Avicel PH102 had better effect in liquidity and compressibility on fermented cordyceps powder than pregelatinized starch. The study on the impact of directly compressed auxiliary materials on the powder property of fermented cordyceps powder had guiding significant to the research of fermented cordyceps powder tablets, and could provide basis for the development of fermented cordyceps powder tablets.

Scaling of wet granular flows in a rotating drum

NASA Astrophysics Data System (ADS)

Jarray, Ahmed; Magnanimo, Vanessa; Ramaioli, Marco; Luding, Stefan

2017-06-01

In this work, we investigate the effect of capillary forces and particle size on wet granular flows and we propose a scaling methodology that ensures the conservation of the bed flow. We validate the scaling law experimentally by using different size glass beads with tunable capillary forces. The latter is obtained using mixtures of ethanol-water as interstitial liquid and by increasing the hydrophobicity of glass beads with an ad-hoc silanization procedure. The scaling methodology in the flow regimes considered (slipping, slumping and rolling) yields similar bed flow for different particle sizes including the angle of repose that normally increases when decreasing the particle size.

Detailed record of SO2 emissions from Pu'u `O`o between episodes 33 and 34 of the 1983-86 ERZ eruption, Kilauea, Hawaii

USGS Publications Warehouse

Chartier, T.A.; Rose, William I.; Stokes, J.B.

1988-01-01

A tripod-mounted correlation spectrometer was used to measure SO2 emissions from Pu`u `O`o vent, mid-ERZ, Kilauea, Hawaii between Episodes 33 and 34 (June 13 to July 6, 1985). In 24 repose days, 906 measurements were collected, averaging 38 determinations/day. Measurements reflect 13% of the total 576 hours of the repose and 42% of the bright daylight hours. The average SO2 emission for the 24-day repose interval is 167??83 t/d, a total of 4000 tonnes emitted for the entire repose. The large standard deviation reflects the "puffing" character of the plume. The overall rate of SO2 degassing gently decreased with a zero-intercept of 44-58 days and was interrupted by two positive peaks. The data are consistent with the gas emanating from a cylindrical conduit of 50 meter diameter and a length of 1700 meters which degasses about 50% of its SO2 during 24 days. This is in support of the Pu'u `O`o model of Greenland et al. (1987). 36 hours before the onset of Episode 34 (July 5-6, 1985), elevated SO2 emissions were detected while the magma column was extremely active ultimately spilling over during dome fountaining. A "mid-repose" anomaly of SO2 emission (June 21-22, 1985) occurs two days before a sudden increase in the rate of summit inflation (on June 24, 1985), suggesting magma was simultaneously being injected in both the ERZ and summit reservoir until July 24 when it was channelled only to the summit reservoir. This implies degassing magma is sensitive to perturbations within the rift zone conduit system and may at times reflect these disturbances. Periods of 7-45 min are detected in the daily SO2 emissions, which possibly reflect timing of convective overturn in the cylindrical magma body. If the 33-34 repose interval is considered representative of other repose periods, the ERZ reposes of Jan 1983-Jan 1986 ERZ activity, contributed 1.6 ?? 105 tonnes of SO2 to the atmosphere. Including summit fuming from non-eruptive fumaroles (2.7 ?? 105 tonnes SO2); 28% of the total SO2 budget from Kilauea between Jan 1983 to Jan 1986 was contributed by quiescent degassing, and the remainder was released during explosive fountaining episodes. ?? 1988 Springer-Verlag.

Granular flows: fundamentals and applications

NASA Astrophysics Data System (ADS)

Cleary, Paul W.

DEM allows the prediction of complex industrial and geophysical particle flows. The importance of particle shape is demonstrated through a series of simple examples. Shape controls resistance to shear, the magnitude of collision stress, dilation and the angle of repose. We use a periodic flow of a bed of particles to demonstrate the different states of granular matter, the generation of dilute granular flow when granular temperature is high and the flow dependent nature of the granular thermodynamic boundary conditions. A series of industrial case studies examines how DEM can be used to understand and improve processes such as separation, mixing, grinding, excavation, hopper discharge, metering and conveyor interchange. Finally, an example of landslide motion over real topography is presented.

Numerical modeling of local scour around hydraulic structure in sandy beds by dynamic mesh method

NASA Astrophysics Data System (ADS)

Fan, Fei; Liang, Bingchen; Bai, Yuchuan; Zhu, Zhixia; Zhu, Yanjun

2017-10-01

Local scour, a non-negligible factor in hydraulic engineering, endangers the safety of hydraulic structures. In this work, a numerical model for simulating local scour was constructed, based on the open source code computational fluid dynamics model OpenFOAM. We consider both the bedload and suspended load sediment transport in the scour model and adopt the dynamic mesh method to simulate the evolution of the bed elevation. We use the finite area method to project data between the three-dimensional flow model and the two-dimensional (2D) scour model. We also improved the 2D sand slide method and added it to the scour model to correct the bed bathymetry when the bed slope angle exceeds the angle of repose. Moreover, to validate our scour model, we conducted and compared the results of three experiments with those of the developed model. The validation results show that our developed model can reliably simulate local scour.

Linking flowability and granulometry of lactose powders.

PubMed

Boschini, F; Delaval, V; Traina, K; Vandewalle, N; Lumay, G

2015-10-15

The flowing properties of 10 lactose powders commonly used in pharmaceutical industries have been analyzed with three recently improved measurement methods. The first method is based on the heap shape measurement. This straightforward measurement method provides two physical parameters (angle of repose αr and static cohesive index σr) allowing to make a first screening of the powder properties. The second method allows to estimate the rheological properties of a powder by analyzing the powder flow in a rotating drum. This more advanced method gives a large set of physical parameters (flowing angle αf, dynamic cohesive index σf, angle of first avalanche αa and powder aeration %ae) leading to deeper interpretations. The third method is an improvement of the classical bulk and tapped density measurements. In addition to the improvement of the measurement precision, the densification dynamics of the powder bulk submitted to taps is analyzed. The link between the macroscopic physical parameters obtained with these methods and the powder granulometry is analyzed. Moreover, the correlations between the different flowability indexes are discussed. Finally, the link between grain shape and flowability is discussed qualitatively. Copyright © 2015 Elsevier B.V. All rights reserved.

25. FRONT END LOADERS MOMENTARILY IN REPOSE IN THE ORE ...

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

25. FRONT END LOADERS MOMENTARILY IN REPOSE IN THE ORE STORAGE YARD. AN ORE BRIDGE THAT FORMERLY TRANSFERRED ORE WITHIN THE STORAGE YARD WAS DESTROYED BY A BLIZZARD IN 1978. - Pennsylvania Railway Ore Dock, Lake Erie at Whiskey Island, approximately 1.5 miles west of Public Square, Cleveland, Cuyahoga County, OH

Geomorphological features of rootless cones in Myvatn, Iceland in comparison with Martian candidates

NASA Astrophysics Data System (ADS)

Noguchi, R.; Kurita, K.

2015-12-01

Rootless cones (RC) have not been paid much attention so far because of their limited locations and their small size. They are formed by repeated phreatovolcanic explosions by lava-waterlogged sediments interactions. While the distribution is limited on the Earth, they have been pervasively recognized on Mars (e.g., Greeley and Fagents, 2001) and considered as a key marker in identifying lava flow. Although in-depth morphological comparisons are necessary, the terrestrial standard is not sufficient. Recent studies have clarified detailed characteristics of the distribution in the context of lava flow dynamics in Laki, Iceland (Hamilton et al., 2010a,b). However, we are still lacking of sufficient data of the morphology. To construct the terrestrial reference, we performed survey in Myvatn, Iceland.About 2300 years ago, lava flowed into old-Lake Myvatn, then formed RCs (Thorarinsson, 1953). There exists 3 morphological types; Single Cone (SC), a conical edifice with a summit crater, Double Cone (DC), composed of an inner cone with a summit crater within the summit crater of an outer cone, and multiple cone, similar to DC but with several inner cones. Through aerial photo survey, 1154 RCs (1056 are SC, 78 are DC and 20 are multiple one) are identified in this area. To know high-resolution topography of them, we apply kinematic GPS. Constituent materials of RCs are analyzed focusing on their bulk density, vesicularity, and grain size distribution.Geomorphological features of RCs are strongly correlated with its location and constituent materials. The crater diameter/bottom diameter ratio of cone, which is considered as an indicator of the explosivity, is larger around the lake and smaller far way from the lava source. This suggests an importance of available thermal energy as well as the water supply. The edifice morphology is grouped into 5 types; I: constant slopes that reach the repose angle; II: constant slopes lower than the repose angle; III: variable slopes with a step; IV: variable slopes that get steeper with higher altitude; and V: variable and small slope angles. We found these types correspond to their constituent materials and volumes. In this presentation, we show the relationship between RC morphology and other parameters, which can be useful as well as the planetary volcanology.

27. HULETT ORE UNLOADERS TEMPORARILY IN REPOSE, AS A NEW ...

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

27. HULETT ORE UNLOADERS TEMPORARILY IN REPOSE, AS A NEW SKIP TIES UP AT DOCK. THE UNLOADERS OPERATE ALMOST CONTINUOUSLY DURING THE SHIPPING SEASON, WHICH USUALLY RUNS FROM APRIL UNTIL LATE DECEMBER OR EARLY JANUARY. VIEW HERE IS LOOKING NORTHEAST. - Pennsylvania Railway Ore Dock, Lake Erie at Whiskey Island, approximately 1.5 miles west of Public Square, Cleveland, Cuyahoga County, OH

A Monte Carlo model for the gardening of the lunar regolith

NASA Technical Reports Server (NTRS)

Arnold, J. R.

1975-01-01

The processes of movement and turnover of the lunar regolith are described by a Monte Carlo model. The movement of material by the direct cratering process is the dominant mode, but slumping is also included for angles exceeding the static angle of repose. Using a group of interrelated computer programs, a large number of properties are calculated, including topography, formation of layers, depth of the disturbed layer, nuclear-track distributions, and cosmogenic nuclides. In the most complex program, the history of a 36-point square array is followed for times up to 400 million years. The histories generated are complex and exhibit great variety. Because a crater covers much less area than its ejecta blanket, there is a tendency for the height change at a test point to exhibit periods of slow accumulation followed by sudden excavation. In general, the agreement with experiment and observation seems good, but two areas of disagreement stand out. First, the calculated surface is rougher than that observed. Second, the observed bombardment ages, of the order 400 million are shorter than expected (by perhaps a factor of 5).

[Improvement of powder flowability and hygroscopicity of traditional Chinese medicine extract by surface coating modification technology].

PubMed

Zeng, Rong-Gui; Jiang, Qie-Ying; Liao, Zheng-Gen; Zhao, Guo-Wei; Luo, Yun; Luo, Juan; Lv, Dan

2016-06-01

To study the improvement of powder flowability and hygroscopicity of traditional Chinese medicine extract by surface coating modification technology. The 1% hydrophobic silica nanoparticles were used as surface modifier, and andrographis extract powder was taken as a model drug. Three different techniques were used for coating model drugs, with angle of repose, compressibility, flat angle and cohesion as the comprehensive evaluation indexes for the powder flowability. The powder particle size and the size distribution were measured by Mastersizer 2000. FEI scanning electron microscope was used to observe the surface morphology and structure of the powder. The percentage of Si element on the powder surface was measured by energy dispersive spectrometer. The hygroscopicity of powder was determined by Chinese pharmacopoeia method. All of the three techniques can improve the flowability of powder extract. In particular, hygroscopicity of extract powder can also be improved by dispersion and then high-speed mixing, which can produce a higher percentage of Si element on the powder surface. The improvement principle may be correlated with a modifier adhered to the powder surface. Copyright© by the Chinese Pharmaceutical Association.

Studies on the compressibility of wax matrix granules of acetaminophen and their admixtures with various tableting bases.

PubMed

Uhumwangho, M U; Okor, R S

2006-04-01

Matrix granules of acetaminophen have been formed by a melt granulation process whereby the acetaminophen powder was triturated with the melted wax--goat wax, glyceryl monostearate or carnuba wax. The compressibility of the matrix granules and their admixture, with diluent granules (lactose, alpha-cellulose or microcrystalline cellulose) was investigated. The granules were compressed to tablets at a constant load (30 arbitrary units on the load scale) of a manesty single punch machine. Resulting tablets were evaluated for tensile strength (T) and disintegration times (DT). Granule flow was determined by measuring their angle of repose when allowed to fall freely on a level surface. Matrix granules prepared by melt granulation with goat wax or glyceryl monostearate were too sticky and therefore did not flow at all. They were also poorly compressible (T values = 0.20MN/m2). Inclusion of the diluent remarkably improved granule flow property and compressibility. The T values of the tablets (measure of compressibility) increased from about 0.24 to 0.65 MN/m2 during increase in diluent (lactose) content from 20 to 80 %w/w. Microcrystalline cellulose and alpha-cellulose were more effective than lactose in promoting compressibility of the granules. By contrast the matrix granules formed with carnuba wax were free flowing (angle of repose, 18.60). Addition of the diluent further improved flowability slightly. The matrix granules (without a diluent) were readily compressible (T value, 1.79MN/m2). Addition of the diluent (80%w/w) reduced T values (MN/m2) slightly to 1.32 (lactose), 1.48 (alpha-cellulose) and 1.74 (microcrystalline cellulose). Tablets of the matrix granules only, disintegrated rapidly within 3 minutes. DT was further reduced to <30 s by addition of any of the diluents. The indication is that the inclusion of the diluents studied can be used to improve the compressibility of the otherwise poorly compressible matrix granules. Based on the flowability, compressibility, and disintegration data, carnuba wax proved most promising in the melt granulation of the test drug for sustained release applications.

Large wind ripples on Mars: A record of atmospheric evolution

NASA Astrophysics Data System (ADS)

Lapotre, M. G. A.; Ewing, R. C.; Lamb, M. P.; Fischer, W. W.; Grotzinger, J. P.; Rubin, D. M.; Lewis, K. W.; Ballard, M. J.; Day, M.; Gupta, S.; Banham, S. G.; Bridges, N. T.; Des Marais, D. J.; Fraeman, A. A.; Grant, J. A.; Herkenhoff, K. E.; Ming, D. W.; Mischna, M. A.; Rice, M. S.; Sumner, D. A.; Vasavada, A. R.; Yingst, R. A.

2016-07-01

Wind blowing over sand on Earth produces decimeter-wavelength ripples and hundred-meter- to kilometer-wavelength dunes: bedforms of two distinct size modes. Observations from the Mars Science Laboratory Curiosity rover and the Mars Reconnaissance Orbiter reveal that Mars hosts a third stable wind-driven bedform, with meter-scale wavelengths. These bedforms are spatially uniform in size and typically have asymmetric profiles with angle-of-repose lee slopes and sinuous crest lines, making them unlike terrestrial wind ripples. Rather, these structures resemble fluid-drag ripples, which on Earth include water-worked current ripples, but on Mars instead form by wind because of the higher kinematic viscosity of the low-density atmosphere. A reevaluation of the wind-deposited strata in the Burns formation (about 3.7 billion years old or younger) identifies potential wind-drag ripple stratification formed under a thin atmosphere.

Large wind ripples on Mars: A record of atmospheric evolution

USGS Publications Warehouse

Lapotre, M G; Ewing, R C; Lamb, M P; Fischer, W W; Grotzinger, J P; Rubin, D M; Lewis, K W; Ballard, M; Day, Mitch D.; Gupta, S.; Banham, S G; Bridges, N T; Des Marais, D J; Fraeman, A A; Grant, J A; Herkenhoff, Kenneth E.; Ming, D W; Mischna, M A; Rice, M S; Sumner, D A; Vasavada, A R; Yingst, R A

2016-01-01

Wind blowing over sand on Earth produces decimeter-wavelength ripples and hundred-meter– to kilometer-wavelength dunes: bedforms of two distinct size modes. Observations from the Mars Science Laboratory Curiosity rover and the Mars Reconnaissance Orbiter reveal that Mars hosts a third stable wind-driven bedform, with meter-scale wavelengths. These bedforms are spatially uniform in size and typically have asymmetric profiles with angle-of-repose lee slopes and sinuous crest lines, making them unlike terrestrial wind ripples. Rather, these structures resemble fluid-drag ripples, which on Earth include water-worked current ripples, but on Mars instead form by wind because of the higher kinematic viscosity of the low-density atmosphere. A reevaluation of the wind-deposited strata in the Burns formation (about 3.7 billion years old or younger) identifies potential wind-drag ripple stratification formed under a thin atmosphere.

Drug particle size influence on enteric beads produced by a droplet extrusion/precipitation method.

PubMed

Cerdeira, A M; Gouveia, L F; Goucha, P; Almeida, A J

2000-01-01

The influence of drug particle size on the production of enteric beads by a polymer precipitation technique was investigated. Drug particle dimensions are known to play an important role in most microencapsulation techniques. Bead morphology was greatly influenced by drug particle size, and spherical shaped beads could only be obtained after size reduction of nimesulide crystals. This is confirmed by the angle of repose measurements, which show a significant decrease in theta values when beads are formulated with smaller drug particles. Furthermore, results show that drug encapsulation efficiency and in vitro drug release rates are also greatly dependent on both drug particle size and drug/polymer ratio in the initial suspension. Preparations containing 10.2 microm drug particles show a two-fold increase in the release rates when compared to those prepared with 40 microm particles.

Lower Lip Suspension Using Bilateral Temporalis Muscle Flaps and Fascia Lata Grafts

DTIC Science & Technology

2012-01-01

from recurrent lower lip drooping, mani- fested as drooling, dribbling, and speech problems, and it is a cause of much social embarrassment. The ideal...to simulate the lower lip in repose , erring on the tight side with the expectation that some laxity will result postoperatively (Fig. 2). Fig. 1. A...lower lip in repose , erring on the tight side with the expec- tation that some laxity will result postoperatively. Fig. 3. A 16-year-old girl

Food powders flowability characterization: theory, methods, and applications.

PubMed

Juliano, Pablo; Barbosa-Cánovas, Gustavo V

2010-01-01

Characterization of food powders flowability is required for predicting powder flow from hoppers in small-scale systems such as vending machines or at the industrial scale from storage silos or bins dispensing into powder mixing systems or packaging machines. This review covers conventional and new methods used to measure flowability in food powders. The method developed by Jenike (1964) for determining hopper outlet diameter and hopper angle has become a standard for the design of bins and is regarded as a standard method to characterize flowability. Moreover, there are a number of shear cells that can be used to determine failure properties defined by Jenike's theory. Other classic methods (compression, angle of repose) and nonconventional methods (Hall flowmeter, Johanson Indicizer, Hosokawa powder tester, tensile strength tester, powder rheometer), used mainly for the characterization of food powder cohesiveness, are described. The effect of some factors preventing flow, such as water content, temperature, time consolidation, particle composition and size distribution, is summarized for the characterization of specific food powders with conventional and other methods. Whereas time-consuming standard methods established for hopper design provide flow properties, there is yet little comparative evidence demonstrating that other rapid methods may provide similar flow prediction.

Infections fongiques des brûlé : revue

PubMed Central

Arnould, JF.; Le Floch, R.

2015-01-01

Summary Les infections fongiques locales ou générales sont souvent d’une extrême gravité chez les brûlés. Les brûlés combinent de nombreux facteurs de risque à une immunodépression induite par la brûlure. Les infections de plaies sont le fait des genres Candida, Aspergillus et des agents de mucormycoses. Ces deux derniers cas sont à l’origine de lésions particulièrement sévères. Leur diagnostic repose sur la biopsie cutanée avec examens mycologique et anatomopathologique. Le traitement est essentiellement chirurgical, associé à une antibiothérapie adaptée. Les septicémies sont le fait de levures, essentiellement du genre Candida. Le diagnostic en est difficile dans le contexte des brûlés et repose souvent sur une forte suspicion clinique. Leur traitement repose sur les échinocandines et plus secondairement sur le fluconazole. PMID:26668558

MGS Mars Orbiter Laser Altimeter (MOLA) - Mars/Earth Relief Comparison

NASA Technical Reports Server (NTRS)

1997-01-01

Comparison of the cross-sectional relief of the deepest portion of the Grand Canyon (Arizona) on Earth versus a Mars Orbiter Laser Altimeter (MOLA) view of a common type of chasm on Mars in the western Elysium region. The MOLA profile was collected during the Mars Global Surveyor Capture Orbit Calibration Pass on September 15, 1997. The Grand Canyon topography is shown as a trace with a measurement every 295 feet (90 meters) along track, while that from MOLA reflects measurements about every 970 feet (400 meters) along track. The slopes of the steep inner canyon wall of the Martian feature exceed the angle of repose, suggesting relative youth and the potential for landslides. The inner wall slopes of the Grand Canyon are less than those of the Martian chasm, reflecting the long period of erosion necessary to form its mile-deep character on Earth.

Ridges on Europa: Origin by Incremental Ice-Wedging

NASA Technical Reports Server (NTRS)

Melosh, H. J.; Turtle, E. P.

2004-01-01

The surface of Europa is covered by ridges that display a variety of morphologies . The most common type is characterized by a double ridge divided by an axial trough. These ridges are, in general, narrow (typically only a few km across) and remarkably linear. They are up to a few hundred meters high and the inner and outer slopes appear to stand at the angle of repose . A number of diverse mechanisms have been proposed to explain the formation of these ubiquitous features , although none can fully account for all of their observed characteristics. We propose a different formation theory in which accumulation of material within cracks that open during the extensional phase of the tidal cycle prevents complete closure of the cracks during the tidal cycle s compressional phase. This accumulation deforms the surrounding ice and, in time, results in the growth of a landform remarkably similar to the ridges observed on Europa.

Erosion and flow of hydrophobic granular materials

NASA Astrophysics Data System (ADS)

Utter, Brian; Benns, Thomas; Mahler, Joseph

2013-11-01

We experimentally investigate submerged granular flows of hydrophobic and hydrophilic grains both in a rotating drum geometry and under erosion by a surface water flow. While slurry and suspension flows are common in nature and industry, effects of surface chemistry on flow behavior have received relatively little attention. In the rotating drum , we use varying concentrations of hydrophobic and hydrophilic grains of sand submerged in water rotated at a constant angular velocity. Sequential images of the resulting avalanches are taken and analyzed. High concentrations of hydrophobic grains result in an effectively cohesive interaction between the grains forming aggregates, with aggregate size and repose angle increasing with hydrophobic concentration. However, the formation and nature of the aggregates depends significantly on the presence of air in the system. We present results from a related experiment on erosion by a surface water flow designed to characterize the effects of heterogeneous granular surfaces on channelization and erosion. Supported by NSF CBET Award 1067598.

Erosion and flow of hydrophobic granular materials

NASA Astrophysics Data System (ADS)

Utter, Brian; Benns, Thomas; Foltz, Benjamin; Mahler, Joseph

2015-03-01

We experimentally investigate submerged granular flows of hydrophobic and hydrophilic grains both in a rotating drum geometry and under erosion by a surface water flow. While slurry and suspension flows are common in nature and industry, effects of surface chemistry on flow behavior have received relatively little attention. In the rotating drum, we use varying concentrations of hydrophobic and hydrophilic grains of sand submerged in water rotated at a constant angular velocity. Sequential images of the resulting avalanches are taken and analyzed. High concentrations of hydrophobic grains result in an effectively cohesive interaction between the grains forming aggregates, with aggregate size and repose angle increasing with hydrophobic concentration. However, the formation and nature of the aggregates depends significantly on the presence of air in the system. We present results from a related experiment on erosion by a surface water flow designed to characterize the effects of heterogeneous granular surfaces on channelization and erosion.

Fluids Demonstrations: Trailing Vortices, Plateau Border, Angle of Repose, and Flow Instability

NASA Astrophysics Data System (ADS)

Shakerin, Said

2018-04-01

Demonstrations of physics phenomena via relatively simple devices and toys have been around for a long time. Because of the pedagogical value of demonstrations, this journal and other periodicals have published papers on the subject of classroom demonstrations including those related to fluid mechanics. Four new, low-cost apparatuses that demonstrate a variety of fluid mechanics phenomena are presented in this paper. The apparatuses are self-contained, instantly set up, require no electric power for operation, and are maintenance free. They can be used as demonstration tools to enhance classroom lectures and outreach activities. Alternatively, these apparatuses can be assigned as projects for students to construct and test. Further involvement, from an aesthetic point of view, might be to construct variations of them as decorative objects by collaborating with students/teachers in visual arts. Features of the apparatuses are presented first, followed by notes on fabrication to enable interested readers to replicate them.

Gas seal for an in situ oil shale retort and method of forming thermal barrier

DOEpatents

Burton, III, Robert S.

1982-01-01

A gas seal is provided in an access drift excavated in a subterranean formation containing oil shale. The access drift is adjacent an in situ oil shale retort and is in gas communication with the fragmented permeable mass of formation particles containing oil shale formed in the in situ oil shale retort. The mass of formation particles extends into the access drift, forming a rubble pile of formation particles having a face approximately at the angle of repose of fragmented formation. The gas seal includes a temperature barrier which includes a layer of heat insulating material disposed on the face of the rubble pile of formation particles and additionally includes a gas barrier. The gas barrier is a gas-tight bulkhead installed across the access drift at a location in the access drift spaced apart from the temperature barrier.

Oral Disintegration Tablets of Stavudine for HIV Management: A New Technological Approach

PubMed Central

Sankar, V.; Ramakrishna, B.; Devi, P. Shalini; Karthik, S.

2012-01-01

Stavudine oral disintegration tablets were formulated to minimize the bitter taste and to reduce the first-pass hepatic metabolism. The various precompression parameters like the angle of repose, bulk density, compressibility index and Hausner's ratio were determined for the powder blend. In this study, 14 formulations of stavudine oral disintegration tablet were prepared by direct compression method. The tablets were evaluated for weight variation, percentage friability, disintegration time, hardness, wetting time and water absorption ratio. The in vitro dissolution study results of the batch S1 (stavudine+crospovidone+sodium starch glycollate) are encouraging as highest dissolution rate (99.2% in 100 min) and lowest time of disintegration (56 s) was achieved. The in vivo drug release studies were carried out in rabbits and the relative bioavailability of formulation S1 was found to be 2.83 times greater than that of conventional tablets. PMID:23798782

Oral Disintegration Tablets of Stavudine for HIV Management: A New Technological Approach.

PubMed

Sankar, V; Ramakrishna, B; Devi, P Shalini; Karthik, S

2012-11-01

Stavudine oral disintegration tablets were formulated to minimize the bitter taste and to reduce the first-pass hepatic metabolism. The various precompression parameters like the angle of repose, bulk density, compressibility index and Hausner's ratio were determined for the powder blend. In this study, 14 formulations of stavudine oral disintegration tablet were prepared by direct compression method. The tablets were evaluated for weight variation, percentage friability, disintegration time, hardness, wetting time and water absorption ratio. The in vitro dissolution study results of the batch S1 (stavudine+crospovidone+sodium starch glycollate) are encouraging as highest dissolution rate (99.2% in 100 min) and lowest time of disintegration (56 s) was achieved. The in vivo drug release studies were carried out in rabbits and the relative bioavailability of formulation S1 was found to be 2.83 times greater than that of conventional tablets.

Horizontal ground deformation patterns and magma storage during the Puu Oo eruption of Kilauea volcano, Hawaii: episodes 22-42

USGS Publications Warehouse

Hoffmann, J.P.; Ulrich, G.E.; Garcia, M.O.

1990-01-01

Horizontal ground deformation measurements were made repeatedly with an electronic distance meter near the Puu Oo eruption site approximately perpendicular to Kilauea's east rift zone (ERZ) before and after eruptive episodes 22-42. Line lengths gradually extended during repose periods and rapidly contracted about the same amount following eruptions. The repeated extension and contraction of the measured lines are best explained by the elastic response of the country rock to the addition and subsequent eruption of magma from a local reservoir. The deformation patterns are modeled to constrain the geometry and location of the local reservoir near Puu Oo. The observed deformation is consistent with deformation patterns that would be produced by the expansion of a shallow, steeply dipping dike just uprift of Puu Oo striking parallel to the trend of the ERZ. The modeled dike is centered about 800 m uprift of Puu Oo. Its top is at a depth of 0.4 km, its bottom at about 2.9 km, and the length is about 1.6 km; the dike strikes N65?? E and dips at about 87??SE. The model indicates that the dike expanded by 11 cm during repose periods, for an average volumetric expansion of nearly 500 000 m3. The volume of magma added to the dike during repose periods was variable but correlates positively with the volume of erupted lava of the subsequent eruption and represents about 8% of the new lava extruded. Dike geometry and expansion values are used to estimate the pressure increase near the eruption site due to the accumulation of magma during repose periods. On average, vent pressures increased by about 0.38 MPa during the repose periods, one-third of the pressure increase at the summit. The model indicates that the dikelike body below Puu Oo grew in volume from 3 million cubic meters (Mm3) to about 10-12 Mm3 during the series of eruptions. The width of this body was probably about 2.5-3.0 m. No net long-term deformation was detected along the measured deformation lines. ?? 1990 Springer-Verlag.

Using the Earth as a guide to martian mass movement processes: From form to process

NASA Astrophysics Data System (ADS)

Lanza, N.; Newsom, H. E.; Osterloo, M. M.; Okubo, C. H.

2011-12-01

The discovery of gully features on Mars has led to renewed interest in hillslope processes on that planet, in particular mass movement and the morphologies that it produces. Mass movement is a collection of gravity-driven processes that act to move materials down a hillslope. Here, we examine how mass movements on hillslopes may be expected to differ on Earth and Mars as the result of gravity differences between these planets. Downslope movement of unconsolidated materials is generally controlled by the bulk shear strength of these materials. Although the relationship between gravity and shear strength is largely dependent on variables that are independent of gravity, the lower gravity on Mars is expected to produce some systematic changes in mass movement behaviors that may in turn create morphological features that are observably different from their terrestrial counterparts. After scaling for gravity and modifying empirically derived relationships, we may expect the following differences on martian hillslopes when compared to their terrestrial counterparts: ==On Mars, hillslopes may have steeper angles of repose in fine grained (< ~2 mm) materials, even when dry. No change in angle of repose is expected for larger particles; ==An increase in soil moisture content (e.g., excess pore pressure) is expected to weaken unconsolidated slope materials more on Mars for a particular regolith type, which in turn may produce --An increase in creep rates for a given pore pressure, and --An increase in effectiveness of frost heave to transport materials downslope; ==Processes triggered by saturation may occur at lower pore pressures on Mars; --A smaller amount of fluid is needed to achieve failure; ==Shorter runout lengths are expected for rapid mass movements; ==On Mars, overland flow will exert a proportionally lower shear stress on slope materials; --In cohesive materials, the same volume of water will detach sediments of smaller sizes. On Earth, mass movement processes may be directly observed and measured as they occur, whereas on Mars only the resultant landforms may be studied at present. By understanding how martian hillslope processes are expected to be modified by lower gravity, the interpretation of martian landforms may be greatly aided. Examples of observations that support some of these predicted differences will be presented, with a focus on saturation-triggered events in unconsolidated materials.

Landscape Evolution Associated with Recurring Slope Lineae (RSL) on Mars

NASA Astrophysics Data System (ADS)

McEwen, A. S.; Dundas, C. M.; Chojnacki, M.; Ojha, L.

2016-12-01

RSL are low-albedo features that initiate at bedrock outcrops and extend down steep slopes. Individual slopes may have hundreds of lineae, with widths up to 5 m and lengths up to 1.5 km. RSL appear and lengthen gradually or incrementally, fade when inactive, and recur each year, normally in the warmest season. Small channels (1-20 m wide) are often present and control RSL paths. We have also detected newly-formed topographic land slumps associated with RSL fans in at least 7 locations—4 around a hill in Juventae Chasma, 2 in Garni crater in Melas Chasma, and 1 along wall slopes in Coprates Chasma. This distinctive landform assemblage is seen at several other locations within central and eastern Valles Marineris (VM): Small channels on most slope aspects of isolated hills or crater walls, extending very nearly to the tops of the hills or crater rim, associated with RSL that match the channels in size, and with a set of lobate deposits at the base of RSL fans. RSL activity in VM changes slope aspect with season—N-facing slopes in northern summer and S-facing slopes in southern summer. The slumps form midway down the RSL fans, and have a different seasonality—most active from Ls 0-120, the coldest time of year in VM. Assuming this association between gullies, RSL, and slumps is not coincidental, an integrated landscape evolution model is needed. Perhaps RSL activity carves the small gullies and deposits sediment near the base of angle-of-repose slopes, locally oversteepening the slope, which episodically slumps. RSL activity is seasonal and associated with the transient presence of hydrated salts, which indicates some role for salty water. If the RSL were caused by fluid flow, they should not be precisely confined to angle-of-repose or steeper slopes (>28 deg.), so these seem to be dry granular flows whose activity is triggered by or somehow associated with small amounts of water. There are multiple mysteries, such as how the activity recurs at the same locations for multiple Mars years, how it is nearly synchronized for many individual flows, how dry granular flows could create channels, and why the slumps happen in the cold season. This set of processes does not have a documented terrestrial analog and may prove important to understanding ancient as well as present-day Mars.

Field characteristics of deposits from spatter-rich pyroclastic density currents at Summer Coon volcano, Colorado

NASA Astrophysics Data System (ADS)

Valentine, G. A.; Perry, F. V.; WoldeGabriel, G.

2000-12-01

The Oligocene, deeply eroded Summer Coon composite volcano contains mafic andesite deposits that are massive to poorly bedded, have abundant flattened and deformed spatter clasts, have varying proportions of dense lithic clasts, and are supported mostly by a coarse-ash matrix. Although superficially these deposits resemble typical facies from Strombolian eruptions (emplaced ballistically, by fallout, and by rolling and local grain-avalanches down steep cone slopes), there are several lines of evidence that lead to an interpretation that the deposits were emplaced by pyroclastic density currents. These include local coarse-tail grading, deformation of spatter clasts in a down-flow direction, incorporation of matrix ash and lapilli into flattened spatter clasts, imbrication of large clasts, plastering of spatter on stoss sides of large lithic blocks and lenses of lithic-rich material on lee sides, deposition on angles less than the angle of repose, and a paucity of clast shapes associated with Strombolian mechanisms. The deposit characteristics are consistent with rapid sedimentation from a low-particle-concentration, turbulent flow onto an aggrading bed. We infer two potential mechanisms for generating these density currents: (1) explosive magma-water interaction involving lithic debris and relatively unfragmented melt; and (2) collapse of oversteepened upper cone slopes due to rapid accumulation of spatter from voluminous Strombolian eruptions.

Changing perception: facial reanimation surgery improves attractiveness and decreases negative facial perception.

PubMed

Dey, Jacob K; Ishii, Masaru; Boahene, Kofi D O; Byrne, Patrick J; Ishii, Lisa E

2014-01-01

Determine the effect of facial reanimation surgery on observer-graded attractiveness and negative facial perception of patients with facial paralysis. Randomized controlled experiment. Ninety observers viewed images of paralyzed faces, smiling and in repose, before and after reanimation surgery, as well as normal comparison faces. Observers rated the attractiveness of each face and characterized the paralyzed faces by rating severity, disfigured/bothersome, and importance to repair. Iterated factor analysis indicated these highly correlated variables measure a common domain, so they were combined to create the disfigured, important to repair, bothersome, severity (DIBS) factor score. Mixed effects linear regression determined the effect of facial reanimation surgery on attractiveness and DIBS score. Facial paralysis induces an attractiveness penalty of 2.51 on a 10-point scale for faces in repose and 3.38 for smiling faces. Mixed effects linear regression showed that reanimation surgery improved attractiveness for faces both in repose and smiling by 0.84 (95% confidence interval [CI]: 0.67, 1.01) and 1.24 (95% CI: 1.07, 1.42) respectively. Planned hypothesis tests confirmed statistically significant differences in attractiveness ratings between postoperative and normal faces, indicating attractiveness was not completely normalized. Regression analysis also showed that reanimation surgery decreased DIBS by 0.807 (95% CI: 0.704, 0.911) for faces in repose and 0.989 (95% CI: 0.886, 1.093), an entire standard deviation, for smiling faces. Facial reanimation surgery increases attractiveness and decreases negative facial perception of patients with facial paralysis. These data emphasize the need to optimize reanimation surgery to restore not only function, but also symmetry and cosmesis to improve facial perception and patient quality of life. © 2013 The American Laryngological, Rhinological and Otological Society, Inc.

Enhanced oxidative stability of fish oil by encapsulating in culled banana resistant starch-soy protein isolate based microcapsules in functional bakery products.

PubMed

Nasrin, Taslima Ayesha Aktar; Anal, Anil Kumar

2015-08-01

Oil in water emulsions were produced by the mixture of culled banana resistant starch (CBRS) & soy protein isolate (SPI), mixture of Hylon VII & SPI and SPI with 7.5 and 5 % (w/w) Menhaden fish oil. The emulsions were further freeze- dried obtaining 33 and 50 % oil load microcapsules. The range of particles diameter was 4.11 to 7.25 μm and viscosity was 34.6 to 146.48 cP of the emulsions. Compressibility index (CI), Hasner ratio (HR) and angle of repose (AR) was significantly (p < 0.01) lower of the microcapsules made with starch and protein (CBRS & SPI and Hylon VII & SPI) than that made with protein (SPI) only. Microcapsules composed of CBRS & SPI with 33 % oil load had maximum microencapsulation efficiency (82.49 %) and highest oxidative stability. Muffin made with emulsions containing mixture of CBRS & SPI exhibited less fishy flavour than that containing mixture of Hylon VII & SPI.

Transient behavior of granular materials with symmetric conditions for tumbler shapes and fill fractions

NASA Astrophysics Data System (ADS)

Pohlman, Nicholas; Si, Yun

2014-11-01

The typical granular motion in circular tumblers is considered steady-state since there are no features to disrupt the top surface layer dimension. In polygon tumblers, however, the flowing layer is perpetually changing length, which creates unsteady conditions with corresponding change in the flow behavior. Prior work showed the minimization of free surface energy is independent of tumbler dimension, particle size, and rotation rate. This subsequent research reports on experiments where dimensional symmetry of the free surface in triangular and square tumblers with varying fill fractions do not necessarily produce the symmetric flow behaviors. Results of the quasi-2D tumbler experiment show that other dimensions aligned with gravity and the instantaneous free surface influence the phase when extrema for angle of repose and other flow features occur. The conclusion is that 50% fill fraction may produce geometric symmetry of dimensions, but the symmetry point of flow likely occurs at a lower fill fraction.

Scaling, clustering and avalanches for steel beads in an external magnetic field

NASA Astrophysics Data System (ADS)

Marquinez, Alyse; Thvedt, Ingrid; Lehman, S. Y.; Jacobs, D. T.

2011-03-01

We investigated avalanches using uniform 3mm steel spheres (``beads'') dropped onto a conical bead pile within a uniform magnetic field. The bead pile is built by pouring beads onto a circular base where the bottom layer of beads had been glued randomly. Beads are then individually dropped from a fixed height after which the pile is massed. This process is repeated for thousands of bead drops. By measuring the number of avalanches of a given size that occurred during the experiment, the resulting avalanche size distribution was compared to a power law description as predicted by self-organized criticality. As the magnetic field intensity increased, the beads clustered to give a larger angle of repose and we measured the change in the avalanche size distribution. The moments of the distribution give a sensitive test of mean-field theory as the universality class for these bead piles. We acknowledge support from Research Corporation and NSF-REU grant DMR 0649112.

Formation of recurring slope lineae on Mars by rarefied gas-triggered granular flows

NASA Astrophysics Data System (ADS)

Schmidt, F.; Andrieu, F.; Costard, F.; Kocifaj, M.; Meresescu, A. G.

2017-09-01

Recurring Slope Linae or RSL are seasonal dark features appearing when the soil reaches its maximum temperature. They appear on various slopes at the equator of Mars, in orientation depending on the season. Today, liquid water related processes have been promoted, such as deliquescence of salts. Nevertheless external atmospheric source of water is inconsistent with the observations. Internal source is also very unlikely. We take into consideration here the force occurring when the sun illuminates granular soil in rarefied gas conditions to produce a Knudsen pump. This process significantly lowers the angle of repose of sandy material. Hence, relatively low slope could start to flow. RSL seems to originate from rough terrains and boulders. We propose that the local shadows due to boulders over the soil, is the triggering phenomena. In this case, the Knudsen pump is magnified and could lead to flow. This new exotic dry process involving neither water nor CO2 and is consistent with the seasonal and facet's orientation appearance of RSL.

Modelling sheet-flow sediment transport in wave-bottom boundary layers using discrete-element modelling.

PubMed

Calantoni, Joseph; Holland, K Todd; Drake, Thomas G

2004-09-15

Sediment transport in oscillatory boundary layers is a process that drives coastal geomorphological change. Most formulae for bed-load transport in nearshore regions subsume the smallest-scale physics of the phenomena by parametrizing interactions amongst particles. In contrast, we directly simulate granular physics in the wave-bottom boundary layer using a discrete-element model comprised of a three-dimensional particle phase coupled to a one-dimensional fluid phase via Newton's third law through forces of buoyancy, drag and added mass. The particulate sediment phase is modelled using discrete particles formed to approximate natural grains by overlapping two spheres. Both the size of each sphere and the degree of overlap can be varied for these composite particles to generate a range of non-spherical grains. Simulations of particles having a range of shapes showed that the critical angle--the angle at which a grain pile will fail when tilted slowly from rest--increases from approximately 26 degrees for spherical particles to nearly 39 degrees for highly non-spherical composite particles having a dumbbell shape. Simulations of oscillatory sheet flow were conducted using composite particles with an angle of repose of approximately 33 degrees and a Corey shape factor greater than about 0.8, similar to the properties of beach sand. The results from the sheet-flow simulations with composite particles agreed more closely with laboratory measurements than similar simulations conducted using spherical particles. The findings suggest that particle shape may be an important factor for determining bed-load flux, particularly for larger bed slopes.

Xylan from corn cobs, a promising polymer for drug delivery: production and characterization.

PubMed

Oliveira, Elquio Eleamen; Silva, Acarília Eduardo; Júnior, Toshiyuki Nagashima; Gomes, Monique Christine Salgado; Aguiar, Larissa Muratori; Marcelino, Henrique Rodrigues; Araújo, Ivonete Batista; Bayer, Marc P; Ricardo, Nágila M P S; Oliveira, Anselmo Gomes; Egito, Eryvaldo Sócrates Tabosa

2010-07-01

Although many authors have reported several beneficial effects ascribed to xylan, such as inhibitory action on mutagenicity activity, antiphlogistic effects, and mitogenic and comitogenic activities, few papers have investigated a systematic study on the technological properties of this polymer. The aim of the present work was to evaluate xylan as a promise raw material for the pharmaceutical industry. The water-insoluble xylan samples were extracted from corn cobs following several steps. The obtained powered sample was analyzed by infrared and RMN spectroscopy, and characterized regarding their particle size, bulk and tap densities, compressibility index, compactability, Hausner ratio, and angle of repose. According to the results, infrared and RMN spectroscopy were shown to be able to evaluate the xylan structural conformation and composition, respectively. In addition, rheological data demonstrated that xylan powder obtained from corn cobs may be characterized as a material with low density and very cohesive flow properties. Copyright (c) 2010 Elsevier Ltd. All rights reserved.

Do Recurring Slope Lineae (RSL) Shape their Local Landscapes?

NASA Astrophysics Data System (ADS)

McEwen, A. S.; Dundas, C. M.; Chojnacki, M.; Ojha, L.

2017-12-01

RSL are low-albedo features on Mars that initiate at or near bedrock outcrops and extend down steep slopes, with widths up to 5 m and lengths up to 1.5 km. RSL appear and lengthen gradually or incrementally, fade when inactive, and recur each martian year in the warmest season. There are hundreds of likely RSL sites, each with up to hundreds of lineae. Small gullies (1-20 m wide) are often present and control RSL paths; such small, fresh gullies are otherwise rare in equatorial regions. The RSL flow out to the ends of distinctive fans, which may get reworked by wind-driven ripples or dunes. The fans are often relatively bright but transiently become darker, and may have a distinctive color. We have detected newly-formed topographic slumps associated with RSL fans in 12 locations in Valles Marineris (VM). A distinctive landform assemblage is seen within central and eastern VM: Small channels occur on most slope aspects of isolated hills or crater walls, extend very nearly to the tops of the hills or crater rims, are associated with seasonal RSL that extend the full length of the channels and fans, and there is a set of lobate deposits (from slumps) at the base of RSL fans. RSL activity in VM changes slope aspect with season to favor warm temperatures, but the slumps are most active from Ls 0-120, the coldest time of year in VM, especially on south-facing slopes where most of the new slumps have been seen. This association between gullies, RSL, fans, and slumps suggests integrated landscape evolution. Perhaps RSL activity erodes the small gullies and deposits sediment, creating angle-of-repose sloping fans, sometimes oversteepening the fans to cause slumping. RSL activity is associated with the transient presence of hydrated salts, which may indicate some role for salty water. If the RSL mark fluid flow, they should not be precisely confined to angle-of-repose or steeper slopes (>28°), so these must be dry granular flows with activity possibly triggered by or somehow associated with small amounts of water. There are multiple mysteries, such as how the activity recurs at the same locations for multiple Mars years, how activity is nearly synchronized for many individual flows, why similar hill slopes lack RSL, how they erode narrow gullies, why RSL fans transiently darken, and why the slumps form in the cold season.

Small-scale impacts as potential trigger for landslides on small Solar system bodies

NASA Astrophysics Data System (ADS)

Hofmann, Marc; Sierks, Holger; Blum, Jürgen

2017-07-01

We conducted a set of experiments to investigate whether millimetre-sized impactors impinging on a granular material at several m s-1 are able to trigger avalanches on small, atmosphereless planetary bodies. These experiments were carried out at the Zentrum für angewandte Raumfahrttechnologie und Mikrogravitation (ZARM) drop tower facility in Bremen, Germany to facilitate a reduced gravity environment. Additional data were gathered at Earth gravity levels in the laboratory. As sample materials we used a ground Howardites, Eucrites and Diogenites (HED) meteorite and the Johnson Space Center (JSC) Mars-1 Martian soil simulant. We found that this type of small-scale impact can trigger avalanches with a moderate probability, if the target material is tilted to an angle close to the angle of repose. We additionally simulated a small-scale impact using the discrete element method code esys-particle. These simulations show that energy transfer from impactor to the target material is most efficient at low- and moderate-impactor inclinations and the transferred energy is retained in particles close to the surface due to a rapid dissipation of energy in lower material layers driven by inelastic collisions. Through Monte Carlo simulations we estimate the time-scale on which small-scale impacts with the observed characteristics will trigger avalanches covering all steep slopes on the surface of a small planetary body to be of the order 105 yr.

Historic bluff retreat and stabilization at Flag Harbor, Chesapeake Bay, Maryland

USGS Publications Warehouse

Clark, Inga; Larsen, Curtis E.; McRae, Michele

2002-01-01

Studies of bluff erosion and slope stability along the western shore of Chesapeake Bay suggest relative evolution from steep, eroding coastal bluffs to stable slopes at angles of repose ca. 35 degrees over decades. Because of the dating methods in those studies, it was impossible to precisely define rates of change. The present study provides historic age control. A pair of small harbor structures were constructed in the early 1950's at Chesapeake Beach, MD to maintain a dredged channel to a small marina occupying a ravine in the Calvert Cliffs. Prior to construction, this section of shoreline was comprised of eroding steep bluffs cut into Miocene-age sediments. Downdrift erosion is now apparent south of the structures as is updrift deposition behind the northern jetty. Since construction the updrift sand body has prograded northward and progressively deposited protective beaches along the toes of the bluffs. Former eroding bluffs nearest the harbor are now stable, vegetated slopes at angles near 35 degrees. Slope angles widen to the north and to the northern limit of the sand body. Beyond this are eroding bluffs standing at angles of 70-80 degrees. The relative time required for eroding bluffs to reach stability is estimated by interpolating the distance and time for the sand body to prograde northward since harbor construction. We measured slope angles at intervals northward from the updrift structure for a distance of 2000 feet. A least squares regression of slope angle vs distance showed progressive decrease in angle from north to south. Actively eroding 70-80 degree bluffs gave way to vegetated, but slumping slopes, and finally to stable 35-degree slopes at the harbor. A relationship between time and distance along the shore allowed us to estimate a stabilization time for this location of 35-40 years. The shortness of this time scale allows us to suggest that attempts to artificially stabilize eroding bluffs along this coast is not a simple task of protecting the toes of slopes from wave action. Once shoreline retreat ends, sloughing of sediment from bluff faces gives way to longer-term landslide processes. The bluff top recedes until a stable 35-degree slope is attained. Thus, simple shoreline protection methods may not preserve property at the bluff edge.

Using Computer Simulations to Model Scoria Cone Growth

NASA Astrophysics Data System (ADS)

Bemis, K. G.; Mehta, R. D.

2016-12-01

Scoria cones form from the accumulation of scoria delivered by either bursting lava bubbles (Strombolian style eruptions) or the gas thrust of an eruption column (Hawaiian to sub-Plinian style eruption). In this study, we focus on connecting the distribution of scoria delivery to the eventual cone shape rather than the specifics of the mechanism of delivery. For simplicity, we choose to model ballistic paths, that follow the scoria from ejection from crater to landing on the surface and then avalanching down slope. The first stage corresponds to Strombolian-like bursts of the bubble. The second stage only occurs if the angle of repose is greater than 30 degrees. After this condition is met, the scoria particles grain flow downwards until a stable slope is formed. These two stages of the volcanic eruption repeat themselves in the number of phases. We hypothesize that the horizontal travel distance of the ballistic paths, and as a result the width of the volcano, is primarily dependent of the velocity of the particles bursting from the bubble in the crater. Other parameters that may affect the shape of cinder cones are air resistance on ballistic paths, ranges in particle size, ballistic ejection angles, and the total number of particles. Ejection velocity, ejection angle, particle size and air resistance control the delivery distribution of scoria; a similar distribution of scoria can be obtained by sedimentation from columns and the controlling parameters of such (gas thrust velocity, particle density, etc.) can be related to the ballistic delivery in terms of eruption energy and particle characteristics. We present a series of numerical experiments that test our hypotheses by varying different parameters one or more at a time in sets each designed to test a specific hypothesis. Volcano width increases as ejection velocity, ejection angle (measured from surface), or the total number of scoria particles increases. Ongoing investigations seek the controls on crater width.

Spaceborne radar observations: A guide for Magellan radar-image analysis

NASA Technical Reports Server (NTRS)

Ford, J. P.; Blom, R. G.; Crisp, J. A.; Elachi, Charles; Farr, T. G.; Saunders, R. Stephen; Theilig, E. E.; Wall, S. D.; Yewell, S. B.

1989-01-01

Geologic analyses of spaceborne radar images of Earth are reviewed and summarized with respect to detecting, mapping, and interpreting impact craters, volcanic landforms, eolian and subsurface features, and tectonic landforms. Interpretations are illustrated mostly with Seasat synthetic aperture radar and shuttle-imaging-radar images. Analogies are drawn for the potential interpretation of radar images of Venus, with emphasis on the effects of variation in Magellan look angle with Venusian latitude. In each landform category, differences in feature perception and interpretive capability are related to variations in imaging geometry, spatial resolution, and wavelength of the imaging radar systems. Impact craters and other radially symmetrical features may show apparent bilateral symmetry parallel to the illumination vector at low look angles. The styles of eruption and the emplacement of major and minor volcanic constructs can be interpreted from morphological features observed in images. Radar responses that are governed by small-scale surface roughness may serve to distinguish flow types, but do not provide unambiguous information. Imaging of sand dunes is rigorously constrained by specific angular relations between the illumination vector and the orientation and angle of repose of the dune faces, but is independent of radar wavelength. With a single look angle, conditions that enable shallow subsurface imaging to occur do not provide the information necessary to determine whether the radar has recorded surface or subsurface features. The topographic linearity of many tectonic landforms is enhanced on images at regional and local scales, but the detection of structural detail is a strong function of illumination direction. Nontopographic tectonic lineaments may appear in response to contrasts in small-surface roughness or dielectric constant. The breakpoint for rough surfaces will vary by about 25 percent through the Magellan viewing geometries from low to high Venusian latitudes. Examples of anomalies and system artifacts that can affect image interpretation are described.

Physicochemical characteristics and antioxidant activity of Prunus cerasoides D. Don gum exudates.

PubMed

Malsawmtluangi, C; Thanzami, K; Lalhlenmawia, H; Selvan, Veenus; Palanisamy, Selvamani; Kandasamy, Ruckmani; Pachuau, Lalduhsanga

2014-08-01

The physicochemical properties and antioxidant activity of Prunus cerasoides D. Don gum exudates was investigated in this study. The total carbohydrate and protein content were found to be 73.72±2.44% and 2.33±1.25%, respectively. Analysis of monosaccharide composition by HPLC-RI system after acid hydrolysis of the gum showed the presence of arabinose, galactose, glucose, rhamnose and xylose. The molecular weight of the gum was also found to be 5.55×10(5)Da. FTIR and DSC studies showed characteristics typical of a natural polysaccharide. The viscosity of 2% aqueous solution of the gum exhibited non-Newtonian type of flow and the gum was also found to show pH dependent swelling. Determination of the angle of repose, Carr's index and Hausner ratio indicate the gum possess fairly good powder flow property. The antioxidant properties of the gum were evaluated by determining DPPH and hydroxyl scavenging activities, reducing power and total phenolic contents which showed the gum possess antioxidant property. Copyright © 2014 Elsevier B.V. All rights reserved.

Correlation between loose density and compactibility of granules prepared by various granulation methods.

PubMed

Murakami, H; Yoneyama, T; Nakajima, K; Kobayashi, M

2001-03-23

The objectives of this study were to prepare the lactose granules by various granulation methods using polyethylene glycol 6000 (PEG 6000) as a binder and to evaluate the effects of granulation methods on the compressibility and compactibility of granules in tabletting. Lactose was granulated by seven granulation methods -- four wet granulations including wet massing granulation, wet high-speed mixer granulation, wet fluidized bed granulation and wet tumbling fluidized bed granulation; and three melt granulations including melt high-speed mixer granulation, melt fluidized bed granulation and melt tumbling fluidized bed granulation. The loose density, angle of repose, granule size distribution, mean diameter of granules, and the tensile strength and porosity of tablets were evaluated. The compactibilities of granules were varied by the granulation methods. However, the difference in compactibility of granules could not be explained due to the difference in compressibility, since there was no difference in Heckel plots due to granulation methods. Among their granule properties, the loose density of granules seemed to have a correlation with the tablet strength regardless of the granulation methods.

Comparative studies of binding potential of Prunus armeniaca and Prunus domestica gums in tablets formulations.

PubMed

Rahim, Haroon; Khan, Mir Azam; Sadiq, Abdul; Khan, Shahzeb; Chishti, Kamran Ahmad; Rahman, Inayat U

2015-05-01

The current study was undertaken to compare the binding potential of Prunus armeniaca L. and Prunus domestica L. gums in tablets' formulations. Tablet batches (F-1 to F-9) were prepared Diclofenac sodium as model drug using 5%, 7.5% and 10% of each Prunus armeniaca L., Prunus domestica L. gums as binder. PVP K30 was used as a standard binder. Magnesium stearate was used as lubricant. Flow properties of granules (like bulk density, tapped density, Carr's index, Hausner's ratio, angle of repose) as well as the physical parameters of compressed tablets including hardness, friability, thickness and disintegration time were determined. Flow parameters of granules of all the batches were found good. Physical parameters (drug content, weight variation, thickness, hardness, friability, disintegration time) of formulated tablets were found within limit when tested. The dissolution studies showed that tablets formulations containing each Prunus domestica showed better binding capacity compared to Prunus armeniaca gum. The binding potential increased as the concentration of gums increased. The FTIR spectroscopic investigation showed that the formulations containing plant gum are compatible with the drug and other excipients used.

Effect of species, pretreatments, and drying methods on the functional and pasting properties of high-quality yam flour.

PubMed

Wahab, Bashirat A; Adebowale, Abdul-Rasaq A; Sanni, Silifat A; Sobukola, Olajide P; Obadina, Adewale O; Kajihausa, Olatundun E; Adegunwa, Mojisola O; Sanni, Lateef O; Tomlins, Keith

2016-01-01

The study investigated the functional properties of HQYF (high-quality yam flour) from tubers of four dioscorea species. The tubers were processed into HQYF using two pretreatments (potassium metabisulphite: 0.28%, 15 min; blanching: 70°C, 15 min) and drying methods (cabinet: 60°C, 48 h; sun drying: 3 days). Significant differences (P < 0.05) were observed in pasting characteristics of flours among the four species. The drying method significantly affected only the peak viscosity. The interactive effect of species, pretreatment, and drying methods on the functional properties was significant (P < 0.05) except for emulsification capacity, angle of repose, and least gelation concentration. The significant variation observed in most of the functional properties of the HQYF could contribute significantly to breeding programs of the yam species for diverse food applications. The pastes of flour from Dioscorea dumetorum pretreated with potassium metabisulphite and dried under a cabinet dryer were stable compared to other samples, hence will have better applications in products requiring lower retrogradation during freeze/thaw cycles.

CRADA opportunities in removal of particulates from hot-gas streams by filtration

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

Smith, D H

1995-06-01

Our analyses of samples and operating data from the Pressurized Fluidized Bed Combustion (PFBC), cyclone, and filtration units of the Tidd Clean Coal demonstration facility show that calcined dolomitic sorbent reacted with SO{sub 2} (and O{sub 2}) to form Sulfates (CaSO{sub 4} and CaMgn [SO{sub 4}]n+1) not only in the PFBC bed, but also in the filtration vessel. Analyses of limited data from the journal literature suggest that the filter-vessel reactions may have produced sulfate {open_quotes}necks,{close_quotes} which bonded the particles together, thus substantially increasing the critical angle of repose and shear tensile strengths of the filtered powders. This proposed mechanismmore » rationalizes the {open_quotes}bridging{close_quotes} and other particle-accumulation problems that caused filter breakage. Engineering services potentially available to resolve these problems include elucidation and modeling of ex-situ and in-situ filter-vessel chemistry, measurement and modeling of particulate materials properties, and measurement and modeling of cleaning back-pulse aerodynamics and cleaning efficiencies.« less

Application of halloysite clay nanotubes as a pharmaceutical excipient.

PubMed

Yendluri, Raghuvara; Otto, Daniel P; De Villiers, Melgardt M; Vinokurov, Vladimir; Lvov, Yuri M

2017-04-15

Halloysite nanotubes, a biocompatible nanomaterial of 50-60nm diameter and ca. 15nm lumen, can be used for loading, storage and sustained release of drugs either in its pristine form or with additional polymer complexation for extended release time. This study reports the development composite tablets based on 50wt.% of the drug loaded halloysite mixed with 45wt.% of microcrystalline cellulose. Powder flow and compressibility properties of halloysite (angle of repose, Carr's index, Hausner ratio, Brittle Fracture Index, tensile strength) indicate that halloysite is an excellent tablet excipient. Halloysite tubes can also be filled with nifedipine with ca. 6wt.% loading efficiency and sustained release from the nanotubes. Tablets prepared with drug loaded halloysite allowed for almost zero order nifedipine release for up to 20h. Nifedipine trapped in the nanotubes also protect the drug against light and significantly increased the photostability of the drug. All of these demonstrate that halloysite has the potential to be an excellent pharmaceutical excipient that is also an inexpensive, natural and abundantly available material. Copyright © 2017 Elsevier B.V. All rights reserved.

Degassing and microlite crystallization during pre-climactic events of the 1991 eruption of Mt. Pinatubo, Philippines

USGS Publications Warehouse

Hammer, J.E.; Cashman, K.V.; Hoblitt, R.P.; Newman, S.

1999-01-01

Dacite tephras produced by the 1991 pre-climactic eruptive sequence at Mt. Pinatubo display extreme heterogeneity in vesicularity, ranging in clast density from 700 to 2580 kg m-3. Observations of the 13 surge-producing blasts that preceded the climactic plinian event include radar-defined estimates of column heights and seismically defined eruptive and intra-eruptive durations. A comparison of the characteristics of erupted material, including microlite textures, chemical compositions, and H2O contents, with eruptive parameters suggests that devolatilization-induced crystallization of the magma occurred to a varying extent prior to at least nine of the explosive events. Although volatile loss progressed to the same approximate level in all of the clasts analyzed (weight percent H2O=1.26-1.73), microlite crystallization was extremely variable (0-22%). We infer that syn-eruptive volatile exsolution from magma in the conduit and intra-eruptive separation of the gas phase was facilitated by the development of permeability within magma residing in the conduit. Correlation of maximum microlite crystallinity with repose interval duration (28-262 min) suggests that crystallization occurred primarily intra-eruptively, in response to the reduction in dissolved H2O content that occurred during the preceding event. Detailed textural characterization, including determination of three-dimensional shapes and crystal size distributions (CSD), was conducted on a subset of clasts in order to determine rates of crystal nucleation and growth using repose interval as the time available for crystallization. Shape and size analysis suggests that crystallization proceeded in response to lessening degrees of feldspar supersaturation as repose interval durations increased. We thus propose that during repose intervals, a plug of highly viscous magma formed due to the collapse of vesicular magma that had exsolved volatiles during the previous explosive event. If plug thickness grew proportionally to the square root of time, and if magma pressurization increased during the eruptive sequence, the frequency of eruptive pulses may have been modulated by degassing of magma within the conduit. Dense clasts in surge deposits probably represent plug material entrained by each subsequent explosive event.

Growth of the 2004-2006 lava-dome complex at Mount St. Helens, Washington: Chapter 9 in A volcano rekindled: the renewed eruption of Mount St. Helens, 2004-2006

USGS Publications Warehouse

Vallance, James W.; Schneider, David J.; Schilling, Steve P.; Sherrod, David R.; Scott, William E.; Stauffer, Peter H.

2008-01-01

The chief near-surface controls on spine extrusion during 2004-6 have been vent location, relict topographic surfaces from the 1980s, and spine remnants emplaced previously during the present eruption. In contrast, glacier ice has had minimal influence on spine growth. Ice as thick as 150 m has prevented formation of marginal angle-of-repose talus fans but has not provided sufficient resistance to stop spine growth or slow it appreciably. Spines initially emerged along a relict south-facing slope as steep as 40° on the 1980s dome. The open space of the moat between that dome and the crater walls permitted initial southward migration of recumbent spines. An initial spine impinged on the opposing slopes of the crater and stopped; in contrast, recumbent whaleback spines of phase 3 impinged on opposing walls of the crater at oblique angles and rotated eastward before breaking up. Once spine remnants occupied all available open space to the south, spines thrust over previous remnants. Finally, with south and east portions of the moat filled, spine growth proceeded westward. Although Crater Glacier had only a small influence on the growing spines, spine growth affected the glacier dramatically, initially dividing it into two arms and then bulldozing it hundreds of meters, first east and then west, and heaping it more than 100 m higher than its original altitude.

Mars Environmental Chamber for Dynamic Dust Deposition and Statics Analysis

NASA Technical Reports Server (NTRS)

Moeller, L. E.; Tuller, M.; Islam, M. R.; Baker, L.; Kuhlman, K.

2004-01-01

Recent observations of the 2001 dust storms encircling Mars confirm predictions of environmental challenges for exploration. Martian dust has been found to completely mantle the Martian surface over thousands of square kilometers and the opacity of airborne dust has been shown to be capable of modifying atmospheric temperature, radiative transfer and albedo. Planetary dust cycling dynamics are suggested to be a key factor in the evolution of the Martian surface. Long-term robotic and manned exploration of Mars will be confronted by dust deposition in periods of atmospheric calm and violent wind storms. Aeolian dust deposition recorded during the Mars Pathfinder mission was estimated to fall at rates of 20-45 microns per Earth year. Although many tools of exploration will be challenged by coating, adhesion, abrasion and possible chemical reaction of deposited, wind blown and actively disturbed Martian dust, solar cells are thought to be of primary concern. Recent modeling work of power output by gallium arsenide/germanium solar cells was validated by the Pathfinder Lander data and showed power output decreases of 0.1 to 0.5% per Martian day. A major determinant for the optimal positioning angle of solar panels employed in future missions is the angle of repose of the settling dust particles that is dependent on a variety of physical and chemical properties of the particles, the panel surface, and the environmental conditions on the Mars surface. While the effects of many of these factors are well understood qualitatively, quantitative analyses, especially under physical and chemical conditions prevailing on the Mars surface are lacking.

Discrete element simulations of gravitational volcanic deformation. 1; Deformation structures and geometries

NASA Technical Reports Server (NTRS)

Morgan, Julia K.; McGovern, Patrick J.

2005-01-01

We have carried out two-dimensional particle dynamics simulations of granular piles subject to frictional Coulomb failure criteria to gain a first-order understanding of different modes of gravitational deformation within volcanoes. Under uniform basal and internal strength conditions, granular piles grow self-similarly, developing distinctive stratigraphies, morphologies, and structures. Piles constructed upon cohesive substrates exhibit particle avalanching, forming outward dipping strata and angle of repose slopes. Systematic decreases in basal strength lead to progressively deeper and steeper internal detachment faults and slip along a basal decollement; landslide forms grade from shallow slumps to deep-seated landslide and, finally, to axial subsidence and outward flank displacements, or volcanic spreading. Surface slopes decrease and develop concave up morphologies with decreasing decollement strength; depositional layers tilt progressively inward. Spatial variations in basal strength cause lateral transitions in pile structure, stratigraphy, and morphology. This approximation of volcanoes as Coulomb granular piles reproduces the richness of deformational structures and surface morphologies in many volcanic settings. The gentle slopes of Hawaiian volcanoes and Olympus Mons on Mars suggest weak basal decollements that enable volcanic spreading. High-angle normal faults, favored above weak decollements, are interpreted in both settings and may explain catastrophic sector collapse in Hawaii and broad aureole deposits surrounding Olympus Mons. In contrast, steeper slopes and shallow detachment faults predominate in the Canary Islands, thought to lack a weak decollement, favoring smaller, more frequent slope failures than predicted for Hawaii. The numerical results provide a useful predictive tool for interpreting dynamic behavior and associated geologic hazards of active volcanoes.

SLOPE STABILITY EVALUATION AND EQUIPMENT SETBACK DISTANCES FOR BURIAL GROUND EXCAVATIONS

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

MCSHANE DS

2010-03-25

After 1970 Transuranic (TRU) and suspect TRU waste was buried in the ground with the intention that at some later date the waste would be retrieved and processed into a configuration for long term storage. To retrieve this waste the soil must be removed (excavated). Sloping the bank of the excavation is the method used to keep the excavation from collapsing and to provide protection for workers retrieving the waste. The purpose of this paper is to document the minimum distance (setback) that equipment must stay from the edge of the excavation to maintain a stable slope. This evaluation examinesmore » the equipment setback distance by dividing the equipment into two categories, (1) equipment used for excavation and (2) equipment used for retrieval. The section on excavation equipment will also discuss techniques used for excavation including the process of benching. Calculations 122633-C-004, 'Slope Stability Analysis' (Attachment A), and 300013-C-001, 'Crane Stability Analysis' (Attachment B), have been prepared to support this evaluation. As shown in the calculations the soil has the following properties: Unit weight 110 pounds per cubic foot; and Friction Angle (natural angle of repose) 38{sup o} or 1.28 horizontal to 1 vertical. Setback distances are measured from the top edge of the slope to the wheels/tracks of the vehicles and heavy equipment being utilized. The computer program utilized in the calculation uses the center of the wheel or track load for the analysis and this difference is accounted for in this evaluation.« less

Latent structure analysis in the pharmaceutical process of tablets prepared by wet granulation.

PubMed

Uehara, Naoto; Hayashi, Yoshihiro; Mochida, Hiroshi; Otoguro, Saori; Onuki, Yoshinori; Obata, Yasuko; Takayama, Kozo

2016-01-01

Granule characteristics are some of the important intermediate qualities that determine tablet properties. However, the relationships between granule and tablet characteristics are poorly understood. The aim of this study was to elucidate relationships among formulation factors, granule characteristics, and tablet properties using a non-linear response surface method (RSM) incorporating a thin-plate spline interpolation (RSM-S) and a Bayesian network (BN). Tablets containing lactose (Lac), cornstarch (CS), and microcrystalline cellulose (MCC) were prepared by wet granulation. Ten formulations were prepared by an extreme vertices design. The angle of repose (Y 1 ), compressibility (Y 2 ), cohesion force (Y 3 ), internal friction angle (Y 4 ), and mean particle size (Y 5 ) were measured as granule characteristics. Tensile strength (TS) and disintegration time (DT) were measured as tablet properties. RSM-S results showed that TS increased with increasing amounts of MCC and Lac. DT decreased with increasing amounts of MCC and CS. The optimal BN models were predicted using four evaluation indices -Y 3 was shown to be the most important factor for TS, whereas Y 2 , Y 3 , and Y 4 were relatively important for predicting DT. Moreover, tablets with excellent tablet properties (i.e. high TS and low DT) were produced by relatively high Y 1 , low Y 2 , high Y 3 , high Y 4 , and middle Y 5 values, and resulted from the middle of MCC, middle-to-low CS, low Lac, and middle-to-low magnesium stearate (Mg-St) amounts. The RSM-S and BN techniques are useful for revealing complex relationships among formulation factors, granule characteristics, and tablet properties.

The Application of 3D Printing Technology for Simultaneous Orthognathic Surgery and Mandibular Contour Osteoplasty in the Treatment of Craniofacial Deformities.

PubMed

Xiao, Yanju; Sun, Xiumei; Wang, Lin; Zhang, Yaoyao; Chen, Kai; Wu, Guomin

2017-12-01

Because of the limitation of specific preoperative design and surgical templates, orthognathic surgery and mandibular contour osteoplasty are generally performed in two stages. Three-dimensional printing technology has improved the accuracy of the surgery and results in good surgical predictability easily. This study aims to confirm the effectiveness, feasibility and precision of simultaneous mandibular contour osteoplasty and orthognathic surgery with the assistance of 3D printing technology. Ten patients, who were diagnosed with mandibular hypertrophy and bimaxillary deformities, were included in the study. In addition to conventional orthognathic surgery, mandibular angle ostectomy, mandibular outer cortex grinding or mandibular border ostectomy was designed for mandibular hypertrophy. Optimal osteotomy lines and simulated surgeries were designed according the 3D printing model of the mandible. Then, surgical templates were made on the 3D printing model. No muscle excision was performed in any patient. Preoperative, predicted and postoperative measurements were taken, including the gonial angle (Ar-Go-Me) and the mandibular width (Go-Go). All the patients had a reposeful postoperative recovery, with no indication of obvious infection, facial paralysis, osteonecrosis or bone displacement. The gonial angle was improved from 110.3° ± 11.1 to 121.3° ± 2.9, and the mandibular width was improved from 117.5 mm ± 6.8 to 111.9 mm ± 4.2. The discrepancies between simulation and postoperation of the left gonial angle, the right gonial angle and the mandibular width were 0.56° ± 0.22, 0.65° ± 0.3 and 0.49 mm ± 0.43, respectively. The results of our study illustrated the predictability, feasibility and reliability of simultaneous mandibular contour osteoplasty and orthognathic surgery with the assistance of 3D printing technology. Our technique could achieve functional improvement and an aesthetic profile at the same time. This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Global Landslides on Rapidly Spinning Spheroids

NASA Astrophysics Data System (ADS)

Scheeres, Daniel J.; Sanchez, P.

2013-10-01

The angle of repose and conditions for global landslides on the surfaces of small, rapidly spinning, spheroidal asteroids are studied. Applying techniques of soil mechanics, we develop a theory for, and examples of, how regolith will fail and flow in this microgravity environment. Our motivation is to develop an understanding of the "top-shaped" class of asteroids based on analytical soil mechanics. Our analysis transforms the entire asteroid surface into a local frame where we can model it as a conventional granular pile with a surface slope, acceleration and height variations as a function of the body's spin rate, shape and density. A general finding is that the lowest point on a rapidly spinning spheroid is at the equator with the effective height of surface material monotonically increasing towards the polar regions, where the height can be larger than the physical radius of the body. We study the failure conditions of both cohesionless and cohesive regolith, and develop specific predictions of the surface profile as a function of the regolith angle of friction and the maximum spin rate experienced by the body. The theory also provides simple guidelines on what the shape may look like, although we do not analyze gravitationally self-consistent evolution of the body shape. The theory is tested with soft-sphere discrete element method granular mechanics simulations to better understand the dynamical aspects of global asteroid landslides. We find significant differences between failure conditions for cohesive and cohesionless regolith. In the case of cohesive regolith, we show that extremely small values of strength (much less than that found in lunar regolith) can stabilize a surface even at very rapid spin rates. Cohesionless surfaces, as expected, fail whenever their surface slopes exceed the angle of friction. Based on our analysis we propose that global landslides and the flow of material towards the equator on spheroidal bodies are precipitated by exogenous effects such as impact induced seismic shaking or torques during planetary flybys.

Architectural features of the Kayenta formation (Lower Jurassic), Colorado Plateau, USA: relationship to salt tectonics in the Paradox Basin

NASA Astrophysics Data System (ADS)

Bromley, Michael H.

1991-09-01

Fluvial sandstones of the Kayenta Formation were analyzed using architectural element analysis. Paleocurrent trends, the distribution of lacustrine facies and local silcrete development indicate that synsedimentary movement of evaporites in the underlying Paradox Basin created an unstable basin floor beneath the Kayenta fluvial system. This instability resulted in deflection of fluvial axes, local basin development and local areas of interrupted fluvial deposition with eolian dunes. Paleocurrent trends in the Kayenta system reflect periodic interruptions of southwesterly flow. Salt migrating laterally out of a rim syncline into an adjacent salt anticline resulted in a rim syncline of slight topographic relief. The resulting basin was probably rapidly filled, allowing the resumption of southwesterly flow. Differential movement of salt (incipient solution collapse features (?)) resulted in the formation of small centripetal basins in which playa mudstones formed. A laterally extensive resistant ledge underlies a horizontal surface, suggestive of deflation to the water table of an exposed section of valley fill. A channel scour in the top of one of these surfaces has margins much steeper ( > 60°) than the angle of repose for unconsolidated sand. Early cementation of the exposed floodplain could account for this resistance.

Using Online Databases in Corporate Issues Management.

ERIC Educational Resources Information Center

Thomsen, Steven R.

1995-01-01

Finds that corporate public relations practitioners felt they were able, using online database and information services, to intercept issues earlier in the "issue cycle" and thus enable their organizations to develop more "proactionary" or "catalytic" issues management repose strategies. (SR)

Calibration of discrete element model parameters: soybeans

NASA Astrophysics Data System (ADS)

Ghodki, Bhupendra M.; Patel, Manish; Namdeo, Rohit; Carpenter, Gopal

2018-05-01

Discrete element method (DEM) simulations are broadly used to get an insight of flow characteristics of granular materials in complex particulate systems. DEM input parameters for a model are the critical prerequisite for an efficient simulation. Thus, the present investigation aims to determine DEM input parameters for Hertz-Mindlin model using soybeans as a granular material. To achieve this aim, widely acceptable calibration approach was used having standard box-type apparatus. Further, qualitative and quantitative findings such as particle profile, height of kernels retaining the acrylic wall, and angle of repose of experiments and numerical simulations were compared to get the parameters. The calibrated set of DEM input parameters includes the following (a) material properties: particle geometric mean diameter (6.24 mm); spherical shape; particle density (1220 kg m^{-3} ), and (b) interaction parameters such as particle-particle: coefficient of restitution (0.17); coefficient of static friction (0.26); coefficient of rolling friction (0.08), and particle-wall: coefficient of restitution (0.35); coefficient of static friction (0.30); coefficient of rolling friction (0.08). The results may adequately be used to simulate particle scale mechanics (grain commingling, flow/motion, forces, etc) of soybeans in post-harvest machinery and devices.

Compaction of Confining Materials in Pillar Blast Tests

NASA Astrophysics Data System (ADS)

Petropoulos, N.; Wimmer, M.; Johansson, D.; Nordlund, E.

2018-06-01

Two confined pillar tests were conducted at the Kiirunavaara mine to investigate the degree of compaction of three materials, i.e., 0-32-mm backfilled material, a blend of ore and waste material and caved material. Two blastholes were drilled parallel to each pillar wall, and several measurement holes were drilled in between the blastholes through each pillar. Both the measurement holes and backfilled materials, except the caved material, were instrumented. Two types of measurements were taken: dynamic measurements with accelerometers, and static measurements which considered the location of the instrumentation pre- and post-blast. Dynamic measurements involved the burden movement and the confining material behavior, and static measurements contained the final location of sensors inside and the angle of repose of the confining material. The results showed that the size distribution of the confining material affects its behavior under dynamic loading. The backfilled materials showed an apparent cohesion forming an agglomeration on the surface of the blasted burden. The burden moved as one slab due to simultaneous detonation. A gap was formed between the blasted burden and the new face. This gap was partially filled with burden erosion material which was finer fragmented than the blasted burden material.

Size, shape and flow characterization of ground wood chip and ground wood pellet particles

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

Rezaei, Hamid; Lim, C. Jim; Lau, Anthony

Size, shape and density of biomass particles influence their transportation, fluidization, rates of drying and thermal decomposition. Pelleting wood particles increases the particle density and reduces the variability of physical properties among biomass particles. In this study, pine chips prepared for pulping and commercially produced pine pellets were ground in a hammer mill using grinder screens of 3.2, 6.3, 12.7 and 25.4mmperforations. Pellets consumed about 7 times lower specific grinding energy than chips to produce the same size of particles. Grinding pellets produced the smaller particles with narrower size distribution than grinding chips. Derived shape factors in digital image analysismore » showed that chip particles were rectangular and had the aspect ratios about one third of pellet particles. Pellet particles were more circular shape. The mechanical sieving underestimated the actual particle size and did not represent the size of particles correctly. Instead, digital imaging is preferred. Angle of repose and compressibility tests represented the flow properties of ground particles. Pellet particles made a less compacted bulk, had lower cohesion and did flow easier in a pile of particles. In conclusion, particle shape affected the flow properties more than particle size« less

Formulation and Evaluation of Mouth Disintegrating Tablets of Atenolol and Atorvastatin

PubMed Central

Sarfraz, R. M.; Khan, H. U.; Mahmood, A.; Ahmad, M.; Maheen, S.; Sher, M.

2015-01-01

In this study, mouth-disintegrating tablets of atenolol and atorvastatin combination were formulated using superdisintegrants to impart fast disintegration. Fifteen formulations were prepared based on different concentrations of two superdisintegrants, croscarmellose sodium and Kyron-T134. Three different techniques such as direct compression, effervescent and sublimation were used to study the effect of manufacturing processes, nature and concentration of superdisintegrants on various features of these tablets. Five formulations were made using each method. Precompression studies like bulk density, tapped density, angle of repose, Carr's compressibility index, Hausner's ratio and compatibility studies such as Fourier transform infrared spectroscopy and differential scanning calorimetry were performed. Various features such as hardness, thickness, diameter, weight variation, friability, disintegration time, dissolution studies, wetting time, wetting volume, water absorption ratio, modified disintegration, uniformity of contents and stability were evaluated. Finally results were statistically analyzed by the application of one way ANOVA test. Formulation F13 containing Kyron-T134 (6%) and croscarmellose sodium (2%) was found to be the best among all fifteen formulations prepared in all aspects evaluated. Sublimation method is found to be the best among three methods of preparation used. PMID:25767322

Size, shape and flow characterization of ground wood chip and ground wood pellet particles

DOE PAGES

Rezaei, Hamid; Lim, C. Jim; Lau, Anthony; ...

2016-07-11

Size, shape and density of biomass particles influence their transportation, fluidization, rates of drying and thermal decomposition. Pelleting wood particles increases the particle density and reduces the variability of physical properties among biomass particles. In this study, pine chips prepared for pulping and commercially produced pine pellets were ground in a hammer mill using grinder screens of 3.2, 6.3, 12.7 and 25.4mmperforations. Pellets consumed about 7 times lower specific grinding energy than chips to produce the same size of particles. Grinding pellets produced the smaller particles with narrower size distribution than grinding chips. Derived shape factors in digital image analysismore » showed that chip particles were rectangular and had the aspect ratios about one third of pellet particles. Pellet particles were more circular shape. The mechanical sieving underestimated the actual particle size and did not represent the size of particles correctly. Instead, digital imaging is preferred. Angle of repose and compressibility tests represented the flow properties of ground particles. Pellet particles made a less compacted bulk, had lower cohesion and did flow easier in a pile of particles. In conclusion, particle shape affected the flow properties more than particle size« less

Reconfiguration of a flexible flat plate under snow loading

NASA Astrophysics Data System (ADS)

Gosselin, Frédérick; de Langre, Emmanuel

2015-11-01

Snow and wind constitute two of the main sources of mechanical loading on terrestrial plants. Plants bend and twist with large amplitude to bear these loads. For the past ten years, various authors have sought to decompose the problem of plant reconfiguration under fluid flow into its fundamental mechanical ingredients by studying the reconfiguration of simple flexible structures such as beams, plates, rods and strips. Here, we adopt a similar approach to these studies and consider the snow interception of a flexible flat plate. We performed two sets of experiments on thin flexible rectangular plates supported at their center: in the first one, a plate was subjected to real snowing events; in the second one, a plate was loaded with glass beads acting as a granular media similar to snow. Moreover, a theoretical model coupling the Elastica formulation to a loading with a set angle of repose is developed. The model is found to be in good agreement with the experiments on glass beads. Asymptotic scaling laws can be found similarly to the Vogel exponents of reconfiguring structures. For the real snow loading, it is found that the cohesive force in snow which is highly dependent on the snow temperature complicate things greatly.

Extraction of polysaccharide from fruits of Cordia dichotoma G. Forst using acid precipitation method and its physicochemical characterization.

PubMed

Pawar, Harshal Ashok; Gavasane, Amit Jagannath; Choudhary, Pritam Dinesh

2018-08-01

The objective of the present work was to isolate and characterize polysaccharide from fruits of Cordia dichotoma G. Forst. (Family Boraginaceae). Polysaccharide was isolated by using 1% Hydrochloric acid solution. The isolated polysaccharide was tested for physicochemical characteristics such as solubility, pH (1% w/w in water), swelling capacity, loss on drying, ash value, bulk and tapped density, Carr's capacity, Hausner's ratio and angle of repose. Also isolated polysaccharide was characterized by Differential scanning colorimeter (DSC), Estimation of total sugar content, Rheological study and infrared spectroscopy (FT-IR). The isolated mucilage showed positive results for Molisch's test and negative for Ruthenium red test which indicated presence of carbohydrate and gum. The result of physicochemical characteristics reveals that isolated Cordia dichotoma polysaccharide possesses good flow properties. The total polysaccharide content of Cordia dichotoma polymer isolate was found to be 86.24% (w/w). From this study it can be concluded that the polysaccharide isolated from Cordia dichotoma fruits has the required properties and could be used as an excipient for pharmaceutical dosage forms. Copyright © 2018 Elsevier B.V. All rights reserved.

Pockmark asymmetry and seafloor currents in the Santos Basin offshore Brazil

USGS Publications Warehouse

Schattner, U.; Lazar, M.; Souza, L. A. P.; ten Brink, Uri S.; Mahiques, M. M.

2016-01-01

Pockmarks form by gas/fluid expulsion into the ocean and are preserved under conditions of negligible sedimentation. Ideally, they are circular at the seafloor and symmetrical in profile. Elliptical pockmarks are more enigmatic. They are associated with seafloor currents while asymmetry is connected to sedimentation patterns. This study examines these associations through morphological analysis of new multibeam data collected across the Santos continental slope offshore Brazil in 2011 (353–865 mbsl). Of 984 pockmarks, 78% are both elliptical and asymmetric. Geometric criteria divide the pockmarks into three depth ranges that correlate with a transition between two currents: the Brazil Current transfers Tropical Water and South Atlantic Central Water southwestwards while the Intermediate Western Boundary Current transfers Antarctic Intermediate Water northeastwards. It is suggested that the velocity of seafloor currents and their persistence dictate pockmark ellipticity, orientation and profile asymmetry. Fast currents (>20 cm/s) are capable of maintaining pockmark flank steepness close to the angle of repose. These morphological expressions present direct evidence for an edge effect of the South Atlantic Subtropical Gyre and, in general, provide a correlation between pockmark geometry and seafloor currents that can be applied at other locations worldwide.

Development and evaluation of novel antihypertensive orodispersible tablets.

PubMed

Khan, Hafeez Ullah; Hanif, Muhammad; Sarfraz, Rai M; Maheen, Safirah; Afzal, Samina; Sher, Muhammad; Afzal, Khurram; Mahmood, Asif; Shamim, Ayesha

2017-09-01

Objective of present study was to enhance patient compliance in pediatrics and geriatrics patients of Hypertension. To achieve this target, innovative orodispersible tablets of atenolol and atorvastatin was developed to produce instant action by rapidly disintegrating into oral cavity. Three different techniques like direct compression, effervescent and sublimation methods were used to prepare these tablets (Five batches of tablets by each method) by using two superdisintegrants like Sodium starch glycolate and pregelatinized starch alone and in combination. Pre-formulation studies including rheological analysis (Bulk density, tapped density, Angle of repose, Carr's compressibility index, Hausner's ratio), compatibility studies such as Fourier transform infrared spectrophotometry (FTIR) and Differential scanning colorimetry (DSC), Post-compression and stability studies were also performed. Finally, results were statistically evaluated by the applying one way ANOVA test and mean. It was concluded that the formulation F8 containing Sodium starch glycolate 2% and pregelatinized starch 6% found best regarding disintegration time, wetting volume, wetting time, release studies etc. The order in which drug release was quicker is Pregelatinized starch plus Sodium starch glycolate > Pregelatinized starch > Sodium starch glycolate (primojel). It was concluded that sublimation method was the best among three methods used for orodispersible tablets formulations.

Isolation, characterization and investigation of Cordia dichotoma fruit polysaccharide as a herbal excipient.

PubMed

Pawar, Harshal Ashok; Jadhav, Pravin

2015-01-01

The objective of the present research work was to isolate, purify and characterize Cordia dichotoma gum and investigate its disintegration property in oral tablets. The isolated gum was tested for physicochemical characteristics such as solubility, pH (1% w/w in water), swelling index, loss on drying, ash value, bulk and tapped density, Carr's index, Hausner's ratio and angle of repose. The Orodispersible tablets of valsartan were prepared by direct compression method and evaluated for average weight (mg), drug content (%), thickness (mm), hardness (kg/cm(2)), friability (%), wetting time (sec), water absorption ratio (%) and disintegration time (sec). FTIR studies revealed that there was no interaction between drug, gum and other excipients used in the study. The F4 batch with disintegration time 26.34 ± 0.78 s and in vitro release 99.64 ± 0.43% was selected as optimized formulation. This formulation was compared with conventional marketed formulation and was found superior. Batch F4 was subjected to stability studies for three months and was tested for its disintegration time, drug contents and dissolution behaviour. Batch F4 was found stable for three months at accelerated temperature. Copyright © 2014 Elsevier B.V. All rights reserved.

Who gains clinical benefit from using insulin pump therapy? A qualitative study of the perceptions and views of health professionals involved in the Relative Effectiveness of Pumps over MDI and Structured Education (REPOSE) trial.

PubMed

Lawton, J; Kirkham, J; Rankin, D; White, D A; Elliott, J; Jaap, A; Smithson, W H; Heller, S

2016-02-01

To explore health professionals' views about insulin pump therapy [continuous subcutaneous insulin infusion (CSII)] and the types of individuals they thought would gain greatest clinical benefit from using this treatment. In-depth interviews with staff (n = 18) who delivered the Relative Effectiveness of Pumps Over MDI and Structured Education (REPOSE) trial. Data were analysed thematically. Staff perceived insulin pumps as offering a better self-management tool to some individuals due to the drip feed of insulin, the ability to alter basal rates and other advanced features. However, staff also noted that, because of the diversity of features on offer, CSII is a more technically complex therapy to execute than multiple daily injections. For this reason, staff described how, alongside clinical criteria, they had tended to select individuals for CSII in routine clinical practice based on their perceptions about whether they possessed the personal and psychological attributes needed to make optimal use of pump technology. Staff also described how their assumptions about personal and psychological suitability had been challenged by working on the REPOSE trial and observing individuals make effective use of CSII who they would not have recommended for this type of therapy in routine clinical practice. Our findings add to those studies that highlight the difficulties of using patient characteristics and variables to predict clinical success using CSII. To promote equitable access to CSII, attitudinal barriers and prejudicial assumptions amongst staff about who is able to make effective use of CSII may need to be addressed. © 2015 The Authors. Diabetic Medicine © 2015 Diabetes UK.

Influence of the geometry of protective barriers on the propagation of shock waves

NASA Astrophysics Data System (ADS)

Sochet, I.; Eveillard, S.; Vinçont, J. Y.; Piserchia, P. F.; Rocourt, X.

2017-03-01

The protection of industrial facilities, classified as hazardous, against accidental or intentional explosions represents a major challenge for the prevention of personal injury and property damage, which also involves social and economic issues. We consider here the use of physical barriers against the effects of these explosions, which include the pressure wave, the projection of fragments and the thermal flash. This approach can be recommended for the control of major industrial risks, but no specific instructions are available for its implementation. The influence of a protective barrier against a detonation-type explosion is studied in small-scale experiments. The effects of overpressure are examined over the entire path of the shock wave across the barrier and in the downstream zone to be protected. Two series of barrier structures are studied. The first series (A) of experiments investigates two types of barrier geometry with dimensions based on NATO recommendations. These recommendations stipulate that the barrier should be 2 m higher than the charge height, the thickness at the crest should be more than 0.5 m, while its length should be equal to twice the protected structure length and the bank slope should be equivalent to the angle of repose of the soil. The second series (B) of experiments investigates the influence of geometrical parameters of the barrier (thickness at the crest and inclination angles of the front and rear faces) on its protective effects. This project leads to an advance in our understanding of the physical phenomena involved in the propagation of blast waves resulting from an external explosion, in the area around a protective physical barrier. The study focuses on the dimensioning of protective barriers against overpressure effects arising from detonation and shows the advantage of using a barrier with a vertical front or rear face.

Asteroid Evolution: Role of geotechnical properties

NASA Astrophysics Data System (ADS)

Sanchez Lana, Diego P.

2015-08-01

Over the last decade of Planetary research, the scientific community has made many advances in their understanding of the evolution of asteroids in the Solar System. One particular area of fruitful study started with the bold idea that these small planetary bodies could be gravitational aggregates and initially motivated by several different observations and early simulations.If we start with the idea that asteroids are aggregates of different sized components, and not singular monolithic bodies, it is possible to study them with some of the tools that have been used in the fields of Soil Mechanics and Granular Dynamics. In them, parameters such as porosity, cohesive and tensile strength, angles of friction and repose, particle size distributions, stress states, heterogeneity and yield criteria among others, determine how these granular systems will react when subjected to different, changing, external factors. These external factors are believed to have produced and shaped the asteroids that now exist around us and include solar photon momentum, gravitational tides, micro- and macro-impacts and internal energy dissipation.In this presentation we will review what is known about the surface and interiors of rubble pile asteroids, how different theoretical, experimental and simulation tools have been used to study them, how space mission and ground-based observations have shaped our understanding of their physical reality, and what we expect to learn from future missions. The talk will also touch on some of the latest findings obtained by different groups. In particular we will discuss the rotational evolution of self-gravitating aggregates under the influence of the YORP effect and how their angles of friction, tensile strength, porosity, internal structure and density give rise to different disruption modes and the role they play in the formation of asteroids pairs, tumblers and binary systems.

Effect of compression pressure on inhalation grade lactose as carrier for dry powder inhalations

PubMed Central

Raut, Neha Sureshrao; Jamaiwar, Swapnil; Umekar, Milind Janrao; Kotagale, Nandkishor Ramdas

2016-01-01

Introduction: This study focused on the potential effects of compression forces experienced during lactose (InhaLac 70, 120, and 230) storage and transport on the flowability and aerosol performance in dry powder inhaler formulation. Materials and Methods: Lactose was subjected to typical compression forces 4, 10, and 20 N/cm2. Powder flowability and particle size distribution analysis of un-compressed and compressed lactose was evaluated by Carr's index, Hausner's ratio, the angle of repose and by laser diffraction method. Aerosol performance of un-compressed and compressed lactose was assessed in dispersion studies using glass twin-stage-liquid-impenger at flow rate 40-80 L/min. Results: At compression forces, the flowability of compressed lactose was observed same or slightly improved. Furthermore, compression of lactose caused a decrease in in vitro aerosol dispersion performance. Conclusion: The present study illustrates that, as carrier size increases, a concurrent decrease in drug aerosolization performance was observed. Thus, the compression of the lactose fines onto the surfaces of the larger lactose particles due to compression pressures was hypothesized to be the cause of these observed performance variations. The simulations of storage and transport in an industrial scale can induce significant variations in formulation performance, and it could be a source of batch-to-batch variations. PMID:27014618

Enhancement of solubility and antidiabetic effects of Repaglinide using spray drying technique in STZ-induced diabetic rats.

PubMed

Varshosaz, Jaleh; Minayian, Mohsen; Ahmadi, Mahdieh; Ghassami, Erfaneh

2017-09-01

The purpose of the study was to enhance the solubility of the poorly water-soluble drug, Repaglinide using spray drying based solid dispersion technique by different carriers including Eudragit E100, hydroxyl propyl cellulose Mw 80 000 and poly vinyl pyrollidone K30. Optimization of the best formulation was carried out according to drug solubility, release profile, particle size and angle of repose of the solid dispersions. The optimized sample was characterized using X-ray powder diffraction (XRPD), differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FT-IR). The morphology of the dispersions was studied by SEM. The blood glucose lowering effect of spray dried solid dispersions was studied in normal and streptozocin-induced diabetic rats. The results showed that Eudragit E100 in 1:3 ratio could enhance drug solubility by 100-fold. DSC studies indicated a marked change in melting point of the drug possibly due to strong hydrogen bonds between the drug and Eudragit, while FT-IR study did not show obvious interactions between them. According to XRPD results Repaglinide converted to an amorphous state in the spray dried dispersions. Spray dried Repaglinide reduced the blood glucose level significantly during the 8 h of obtaining blood samples in comparison with untreated drug (p < 0.05).

A novel surfactant-free lipid-based formulation for improving oral bioavailability of loratadine using colloidal silicon dioxide as emulsifier and solid carrier.

PubMed

Huang, Ri; Tan, Yonggang; Shen, Lao; Wang, Tao; Quan, Dongqin

2018-05-08

The purpose of this study was to develop an innovative surfactant-free lipid-based formulation (LF) for improving oral bioavailability of loratadine based on using solid particles colloidal silicon dioxide (CSD) as emulsifier and solid carrier. Loratadine was dissolved in oil solution with the aid of co-solvent and LF were prepared by a simple adsorption and milling technique. The LF Powder was evaluated in terms of angle of repose and X-ray powder diffraction. After dispersing and emulsifying in water, the particle size and morphology were also characterized. In vitro dissolution and pharmacokinetic behavior in vivo were also studied. Orthogonal design indicated that the amount of CSD in formulations had a major and significant influence on emulsification. The optimal formulation showed LF with good flowability and without crystallization or deposition of loratadine in it. After dispersing in water, an emulsion with mean droplet size of 1.2μm was obtained. Although the dissolution of drug from LF was slower in vitro in acidic aqueous solution, pharmacokinetic studies in vivo showed that the bioavailability of loratadine increased 2.49-fold by CF compared to commercial tablet. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

Formulation, Characterization and Physicochemical Evaluation of Ranitidine Effervescent Tablets

PubMed Central

Aslani, Abolfazl; Jahangiri, Hajar

2013-01-01

Purpose: The aim of this study was to design, formulate and physicochemically evaluate effervescent ranitidine hydrochloride (HCl) tablets since they are easily administered while the elderly and children sometimes have difficulties in swallowing oral dosage forms. Methods: Effervescent ranitidine HCl tablets were prepared in a dosage of 300 mg by fusion and direct compression methods. The powder blend and granule mixture were evaluated for various pre-compression characteristics, such as angle of repose, compressibility index, mean particle size and Hausner's ratio. The tablets were evaluated for post-compression features including weight variation, hardness, friability, drug content, dissolution time, carbon dioxide content, effervescence time, pH, content uniformity and water content. Effervescent systems with appropriate pre and post-compression qualities dissolved rapidly in water were selected as the best formulations. Results: The results showed that the flowability of fusion method is more than that of direct compression and the F5 and F6 formulations of 300 mg tablets were selected as the best formulations because of their physicochemical characteristics. Conclusion: In this study, citric acid, sodium bicarbonate and sweeteners (including mannitol, sucrose and aspartame) were selected. Aspartame, mint and orange flavors were more effective for masking the bitter taste of ranitidine. The fusion method is the best alternative in terms of physicochemical and physical properties. PMID:24312854

Enhancement in in vitro anti-angiogenesis activity and cytotoxicity in lung cancer cell by pectin-PVP based curcumin particulates.

PubMed

Gaikwad, Dinanath; Shewale, Rajnita; Patil, Vinit; Mali, Dipak; Gaikwad, Uday; Jadhav, Namdeo

2017-11-01

The aim of this work was to prepare pectin-poly (vinyl pyrrolidone) [PVP] based curcumin particulates to enhance the anticancer potential of curcumin, solubility and allow its localized controlled release. Pectin-PVP based curcumin particulates (PECTIN-PVP CUR) were prepared by spray drying technique in different ratios and were evaluated for surface morphology, micromeritics, flowability, particle size, drug content, in vitro dissolution, inhalable fraction, anti-angiogenesis/angiolysis and cytotoxicity. Results of micromeritic properties, Carr's index, Hausner's ratio and angle of repose were satisfactory. The batch CP3 was considered as optimum, due to excellent flowability, acceptable aggregation and enhanced solubility. The particle size and size distribution data of selected batch CP3 showed 90% of curcumin particulates having size less than 2.74μm, which may deposit to lungs. Twin Impinger studies showed that 29% of respirable fraction was generated, which could be directly delivered to lungs. The in vitro dissolution data showed many fold increase in dissolution rate. Angiolytic activity and MTT assay of PECTIN-PVP CUR have demonstrated enhancement in the anti-tumor potential, compared to curcumin alone. Altogether, PECTIN-PVP CUR were found suitable for local delivery and enhance its anticancer potential of curcumin. Copyright © 2017 Elsevier B.V. All rights reserved.

Self-organizing map analysis using multivariate data from theophylline powders predicted by a thin-plate spline interpolation.

PubMed

Yasuda, Akihito; Onuki, Yoshinori; Kikuchi, Shingo; Takayama, Kozo

2010-11-01

The quality by design concept in pharmaceutical formulation development requires establishment of a science-based rationale and a design space. We integrated thin-plate spline (TPS) interpolation and Kohonen's self-organizing map (SOM) to visualize the latent structure underlying causal factors and pharmaceutical responses. As a model pharmaceutical product, theophylline powders were prepared based on the standard formulation. The angle of repose, compressibility, cohesion, and dispersibility were measured as the response variables. These responses were predicted quantitatively on the basis of a nonlinear TPS. A large amount of data on these powders was generated and classified into several clusters using an SOM. The experimental values of the responses were predicted with high accuracy, and the data generated for the powders could be classified into several distinctive clusters. The SOM feature map allowed us to analyze the global and local correlations between causal factors and powder characteristics. For instance, the quantities of microcrystalline cellulose (MCC) and magnesium stearate (Mg-St) were classified distinctly into each cluster, indicating that the quantities of MCC and Mg-St were crucial for determining the powder characteristics. This technique provides a better understanding of the relationships between causal factors and pharmaceutical responses in theophylline powder formulations. © 2010 Wiley-Liss, Inc. and the American Pharmacists Association

Transient Slope Lineae Formation in a Well-Preserved Crater

NASA Image and Video Library

2017-11-20

This enhanced color image from NASA's Mars Reconnaissance Orbiter (MRO) shows what are called "recurring slope lineae"s in Tivat Crater. The narrow, dark flows descend downhill (towards the upper left). Analysis shows that the flows all end at approximately the same slope, which is similar to the angle of repose for sand. RSL are mostly found on steep rocky slopes in dark regions of Mars, such as the southern mid-latitudes, Valles Marineris near the equator, and in Acidalia Planitia on the northern plains. The appearance and growth of these features resemble seeping liquid water, but how they form remains unclear, and this research demonstrated that the RSL flows seen by HiRISE are likely moving granular material like sand and dust. These findings indicate that present-day Mars may not have a significant volume of liquid water. The water-restricted conditions that exist on Mars would make it difficult for Earth-like life to exist near the surface of the planet. The map is projected here at a scale of 25 centimeters (9.8 inches) per pixel. [The original image scale is 25.6 centimeters (10.8 inches) per pixel (with 1 x 1 binning); objects on the order of 77 centimeters (30.3 inches) across are resolved.] North is up. https://photojournal.jpl.nasa.gov/catalog/PIA22114

Preparation and Characterization of Liquisolid Compacts for Improved Dissolution of Telmisartan

PubMed Central

Narra, Nataraj; Rama Rao, Tadikonda

2014-01-01

The objective of the present work was to obtain pH independent and improved dissolution profile for a poorly soluble drug, telmisartan using liquisolid compacts. Liquisolid compacts were prepared using Transcutol HP as vehicle, Avicel PH102 as carrier, and Aerosil 200 as a coating material. The formulations were evaluated for drug excipient interactions, change in crystallinity of drug, flow properties, and general quality control tests of tablets using Fourier transform infrared (FTIR) spectroscopy, differential scanning calorimetry (DSC), X-ray diffraction (XRD), angle of repose, and various pharmacopoeial tests. In vitro dissolution studies were performed at three pH conditions (1.2, 4.5 and 7.4). Stability studies were performed at 40°C and 75% RH for three months. The formulation was found to comply with Indian pharmacopoeial limits for tablets. FTIR studies confirmed no interaction between drug and excipients. XRD and DSC studies indicate change/reduction in crystallinity of drug. Dissolution media were selected based on the solubility studies. The optimized formulation showed pH independent release profile with significant improvement (P < 0.005) in dissolution compared to plain drug and conventional marketed formulation. No significant difference was seen in the tablet properties, and drug release profile after storage for 3 months. PMID:25371826

Europan double ridge morphometry as a test of formation models

NASA Astrophysics Data System (ADS)

Dameron, Ashley C.; Burr, Devon M.

2018-05-01

Double ridges on the Jovian satellite Europa consist of two parallel ridges with a central trough. Although these features are nearly ubiquitous on Europa, their formation mechanism(s) is (are) not yet well-understood. Previous hypotheses for their formation can be divided into two groups based on 1) the expected interior slope angles and 2) the magnitude of interior/exterior slope symmetry. The published hypotheses in the first ("fracture") group entail brittle deformation of the crust, either by diapirism, shear heating, or buckling due to compression. Because these mechanisms imply uplift of near-vertical fractures, their predicted interior slopes are steeper than the angle of repose (AOR) with shallower exterior slopes. The second ("flow") group includes cryosedimentary and cryovolcanic processes - explosive or effusive cryovolcanism and tidal squeezing -, which are predicted to form ridge slopes at or below the AOR. Explosive cryovolcanism would form self-symmetric ridges, whereas effusive cryolavas and cryo-sediments deposited during tidal squeezing would likely not exhibit slope symmetry. To distinguish between these two groups of hypothesized formation mechanisms, we derived measurements of interior slope angle and interior/exterior slope symmetry at multiple locations on Europa through analysis of data from the Galileo Solid State Imaging (SSI) camera. Two types of data were used: i) elevation data from five stereo-pair digital elevation models (DEMs) covering four ridges (580 individual measurements), and ii) ridge shadow length measurements taken on individual images over 40 ridges (200 individual measurements). Our results shows that slopes measured on our DEMs, located in the Cilix and Banded Plains regions, typically fall below the AOR, and slope symmetry is dominant. Two different shadow measurement techniques implemented to calculate interior slopes yielded slope angles that also fall below the AOR. The shallow interior slopes derived from both techniques weigh against brittle deformation mechanisms. Although shallow slopes could result from degradation, interior/exterior ridge symmetry weighs against ridge degradation as the sole reason for shallow interior slopes. Thus, our results suggest that, for the double ridges analyzed in this work, cryovolcanic or cryosedimentary formation is more likely than brittle deformation, and of those formation mechanisms, explosive cryovolcanism is the double ridge formation mechanism best supported on the basis of interior-exterior slope symmetry.

Surface slope characteristics from Thermal Emission Spectrometer emission phase function observations

NASA Astrophysics Data System (ADS)

Edwards, C. S.; Bandfield, J. L.; Christensen, P. R.

2006-12-01

It is possible to obtain surface roughness characteristics, by measuring a single surface from multiple emission angles and azimuths in the thermal infrared. Surfaces will have different temperatures depending on their orientation relative to the sun. A different proportion of sunlit versus shaded surfaces will be in the field of view based on the viewing orientation, resulting in apparent temperature differences. This difference in temperature can be utilized to calculate the slope characteristics for the observed area. This technique can be useful for determining surface slope characteristics not resolvable by orbital imagery. There are two main components to this model, a surface DEM, in this case a synthetic, two dimensional sine wave surface, and a thermal model (provided by H. Kieffer). Using albedo, solar longitude, slope, azimuth, along with several other parameters, the temperature for each cell of the DEM is calculated using the thermal model. A temperature is then predicted using the same observation geometries as the Thermal Emission Spectrometer (TES) observations. A temperature difference is calculated for the two complementary viewing azimuths and emission angles from the DEM. These values are then compared to the observed temperature difference to determine the surface slope. This method has been applied to TES Emission Phase Function (EPF) observations for both the spectrometer and bolometer data, with a footprint size of 10s of kilometers. These specialized types of TES observations measure nearly the same surface from several angles. Accurate surface kinetic temperatures are obtained after the application of an atmospheric correction for the TES bolometer and/or spectrometer. Initial results include an application to the northern circumpolar dunes. An average maximum slope of ~33 degrees has been obtained, which makes physical sense since this is near the angle of repose for sand sized particles. There is some scatter in the data from separate observations, which may be due to the large footprint size. This technique can be better understood and characterized by correlation with high resolution imagery. Several different surface maps will also be tested in addition to the two dimensional sine wave surface. Finally, by modeling the thermal effects on different particle sizes and land forms, we can further interpret the scale of these slopes.

Water contamination, land prices, and the statute of repose

Treesearch

John F. Chamblee; Carolyn A. Dehring; Craig A. Depken; Joseph R. Nicholson

2015-01-01

We examine how water contamination risk from an inactive hazardous waste site is capitalized into surrounding vacant land prices. After public knowledge of the first instance of off-site contamination, we find that shallow groundwater contamination potential is negatively capitalized into land prices, as is proximity to a known contaminated well. Public knowledge of...

A historical analysis of Plinian unrest and the key promoters of explosive activity.

NASA Astrophysics Data System (ADS)

Winson, A. E. G.; Newhall, C. G.; Costa, F.

2015-12-01

Plinian eruptions are the largest historically recorded volcanic phenomena, and have the potential to be widely destructive. Yet when a volcano becomes newly restless we are unable to anticipate whether or not a large eruption is imminent. We present the findings from a multi-parametric study of 42 large explosive eruptions (29 Plinian and 13 Sub-plinian) that form the basis for a new Bayesian Belief network that addresses this question. We combine the eruptive history of the volcanoes that have produced these large eruptions with petrological studies, and reported unrest phenomena to assess the probability of an eruption being plinian. We find that the 'plinian probability' is increased most strongly by the presence of an exsolved volatile phase in the reservoir prior to an eruption. In our survey 60% of the plinian eruptions, had an excess SO2 gas phase of more than double than it is calculated by petrologic studies alone. Probability is also increased by three related and more easily observable parameters: a high plinian Ratio (that is the ratio of VEI≥4 eruptions in a volcanoes history to the number of all VEI≥2 eruptions in the history), a repose time of more than 1000 years, and a Repose Ratio (the ratio of the average return of VEI≥4 eruptions in the volcanic record to the repose time since the last VEI≥4) of greater than 0.7. We looked for unrest signals that potentially are indicative of future plinian activity and report a few observations from case studies but cannot say if these will generally appear. Finally we present a retrospective analysis of the probabilities of eruptions in our study becoming plinian, using our Bayesian belief network. We find that these probabilities are up to about 4 times greater than those calculate from an a priori assessment of the global eruptive catalogue.

Extracting accurate and precise topography from LROC narrow angle camera stereo observations

NASA Astrophysics Data System (ADS)

Henriksen, M. R.; Manheim, M. R.; Burns, K. N.; Seymour, P.; Speyerer, E. J.; Deran, A.; Boyd, A. K.; Howington-Kraus, E.; Rosiek, M. R.; Archinal, B. A.; Robinson, M. S.

2017-02-01

The Lunar Reconnaissance Orbiter Camera (LROC) includes two identical Narrow Angle Cameras (NAC) that each provide 0.5 to 2.0 m scale images of the lunar surface. Although not designed as a stereo system, LROC can acquire NAC stereo observations over two or more orbits using at least one off-nadir slew. Digital terrain models (DTMs) are generated from sets of stereo images and registered to profiles from the Lunar Orbiter Laser Altimeter (LOLA) to improve absolute accuracy. With current processing methods, DTMs have absolute accuracies better than the uncertainties of the LOLA profiles and relative vertical and horizontal precisions less than the pixel scale of the DTMs (2-5 m). We computed slope statistics from 81 highland and 31 mare DTMs across a range of baselines. For a baseline of 15 m the highland mean slope parameters are: median = 9.1°, mean = 11.0°, standard deviation = 7.0°. For the mare the mean slope parameters are: median = 3.5°, mean = 4.9°, standard deviation = 4.5°. The slope values for the highland terrain are steeper than previously reported, likely due to a bias in targeting of the NAC DTMs toward higher relief features in the highland terrain. Overlapping DTMs of single stereo sets were also combined to form larger area DTM mosaics that enable detailed characterization of large geomorphic features. From one DTM mosaic we mapped a large viscous flow related to the Orientale basin ejecta and estimated its thickness and volume to exceed 300 m and 500 km3, respectively. Despite its ∼3.8 billion year age the flow still exhibits unconfined margin slopes above 30°, in some cases exceeding the angle of repose, consistent with deposition of material rich in impact melt. We show that the NAC stereo pairs and derived DTMs represent an invaluable tool for science and exploration purposes. At this date about 2% of the lunar surface is imaged in high-resolution stereo, and continued acquisition of stereo observations will serve to strengthen our knowledge of the Moon and geologic processes that occur across all of the terrestrial planets.

A Science-Based Understanding of Cermet Processing

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

Cesarano, III, Joseph; Roach, Robert Allen; Kilgo, Alice C.

2006-04-01

This report is a summary of the work completed in FY01 for science-based characterization of the processes used to fabricate 1) cermet vias in source feedthrus using slurry and paste-filling techniques and 2) cermet powder for dry pressing. Common defects found in cermet vias were characterized based on the ability of subsequent processing techniques (isopressing and firing) to remove the defects. Non-aqueous spray drying and mist granulation techniques were explored as alternative methods of creating CND50, the powder commonly used for dry pressed parts. Compaction and flow characteristics of these techniques were analyzed and compared to standard dry-ball-milled CND50. Duemore » to processing changes, changes in microstructure can occur. A microstructure characterization technique was developed to numerically describe cermet microstructure. Machining and electrical properties of dry pressed parts were also analyzed and related to microstructure using this analytical technique.3 Executive SummaryThis report outlines accomplishments in the science-based understanding of cermet processing up to fiscal year 2002 for Sandia National Laboratories. The three main areas of work are centered on 1) increasing production yields of slurry-filled cermets, 2) evaluating the viability of high-solids-loading pastes for the same cermet components, and 3) optimizing cermet powder used in pressing processes (CND50). An additional development that was created as a result of the effort to fully understand the impacts of alternative processing techniques is the use of analytical methods to relate microstructure to physical properties. Recommendations are suggested at the end of this report. Summaries of these four efforts are as follows:1.Increase Production Yields of Slurry-Filled Cermet Vias Finalized slurry filling criteria were determined based on three designs of experiments where the following factors were analyzed: vacuum time, solids loading, pressure drop across the filter paper, slurry injection rate, via prewetting, slurry injection angle, filter paper prewetting, and slurry mixing time. Many of these factors did not have an influence on defect formation. In order of decreasing importance, critical factors for defect formation by slurry filling are vacuum time (20 sec. optimal), slurry solids loading (20.0 g of cermet with 13.00 g of DGBEA solvent (21.2 vol%)), filling with the pipette in a vertical position, and faster injection rates (%7E765 l/s) as preferable to slower. No further recommendations for improvement to this process can be suggested. All findings of the slurry filling process have been transferred to CeramTec, the supplier. Paste filling methods appear to show more promise of increasing production yields. The types of flaws commonly found in slurry-filled vias were identified and followed throughout the entire source feedthru process. In general, all sizes of cracks healed during isopressing and firing steps. Additionally, small to medium sized voids (less than 1/3 the via diameter) can be healed. Porosity will usually lead to via necking, which may cause the part to be out of specification. Large voids (greater 4 than 1/3 of the diameter) and partial fills are not healed or produce significant necking. 2.Viability of High-Solids-Loading-Cermet Paste for Filling Source Feedthru ViaThe paste-filling process is easy to implement and easier to use. The high solids loading (>40 vol %) reduces the incidence of drying defects, which are seen in slurry filled (%7E23 vol %) vias. Additionally, the way in which the vias are filled (the paste is pushed from entrance to exit, displacing air as the paste front progresses), reduces the chance of entrapped voids, which are common in the slurry filling process. From the fair number of samples already filled, the likelihood of this process being a viable and reliable process is very good. Issues of concern for the paste process, as with any new process, are any problems that may arise in subsequent manufacturing stages of the neutron tube that may be affected by subtle changes in microstructure. Both MC4277 and MC4300-type source feedthrus were paste-filled by hand. X-ray analysis showed a much lower existence of voids in the green parts as compared to slurry-filled parts. The paste shows improvements in shelf life (weeks) as compared to slurry (minutes). This method of introducing the cermet to the via also lends itself very well to an automated filling process where a machine can either drill vias or, with the aid of a vision system, find pre-drilled vias and fill them with paste. The pastes used in this work prove the concept of this automated filling process as MC4277 sources have been filled using such a prototype machine, however, better performing pastes can be developed which are less hazardous (aqueous systems). The paste process was also used to successfully fill MC4300 "dogleg" type sources.3.Optimize CND50 Two methods of creating granulated cermet powder for comparison with dry-ball milled CND50 were explored. The first method, non-aqueous spray drying, was performed at Niro Inc. used a 40/60 (wt %) ethanol/toluene solvent and three binder systems; polyvinyl butyral (B79), ethylcellulose (Ethocel), and hydroxypropylcellulose (Klucel). Due to the nature of small spray-dry systems, an excess amount of fines was present in the granulated powder, which may have contributed to the low angles of repose (68 to 78). This is a moderate increase in 5 flowability as standard dry-ball milled powder possesses an angle of repose of 79-89. Mist granulated powders were produced with a tert-butanol solvent and polyvinyl butyral binder system. The angles of repose were more promising (28). More investigation into the mist granulation method is required. Also, aqueous spray drying may be possible with cermet and should be explored. Compaction of all granulated powders is much closer to a proven pressing powder (Sandi94 - angle of repose 29) which should allow cermet to be pressed to near net shape where die filling is difficult for non-flowing powders.4.Microstructure Characterization An analytical technique was developed to numerically characterize microstructures in terms of molybdenum dispersion, homogeneity, and percolation indices. This technique was applied to dry-ball-milled samples of various ball-milling times (0.5 to 20 hours). Significant change in the microstructure could be seen with milling time. Increased milling time caused agglomeration of molybdenum particles, increasing the percolation index, whereas short milling times promoted higher dispersion indices. This phenomenon is contrary to conventional understanding of mixing. However, conventional ball milling does not usually incorporate granules with binder and separate particles. This discrepancy may explain the odd mixing behavior. It is important to note that the high percolation index possessed by long ball mill times showed lower electrical resistance than low-percolation-index microstructures. However, machinability of high percolation, low-dispersion-index microstructures were poor as compared to microstructures with high dispersion indices and moderate percolation indices. This trade-off between dispersion and percolation (at constant molybdenum levels) suggests that microstructures can be achieved that posses good mechanical and electrical properties. Coincidentally, microstructures that satisfy this condition are produced by the standard dry-ball-milled CND50 (4 hour ball mill time). The performance and sensitivity of the microstructure characterization technique should be evaluated, specifically for electrical conductivity. Processing techniques to decrease the percolation index (lowering molybdenum content, excess ball milling, 6 larger molybdenum particles, etc.) should be employed to determine the point where cermet is not conductive or falls below electrical conduction specifications.7« less

Effect of Hydrophobicity on Splash Erosion by a Single Drop Impact: From Model Soil to Real Soil

NASA Astrophysics Data System (ADS)

Ahn, Sujung; Doerr, Stefan H.; Douglas, Peter; Bryant, Robert; Hamlett, Christopher A. E.; McHale, Glen; Newton, Michael I.; Shirtcliffe, Neil J.

2013-04-01

Splash erosion is soil loss caused by raindrop impacts and can be a dominating process in low precipitation events or on barely vegetated slopes. Water repellent soils have been reported to have greater splash loss by multiple drop impacts than wettable soils either due to effects of a water layer (Terry and Shakesby 1993) or a wet crust (Fox et al. 2007) generated by accumulation of water. In previous work, using homogeneous glass beads as model soil material, we found that the impact of a single water drop results in significantly different splash behaviour between hydrophobic and hydrophilic particles (Ahn et al. 2012). Natural soils are more variable in particle shape, surface texture and morphology than the model material used. The aim of the study presented here was to examine to what degree this difference in splash behaviour between hydrophobic and hydrophilic spherical glass particles applies to natural sandy soil material. Splash behaviour of beach sands was compared with that previously obtained for the model material (glass beads) using the same single drop impact test procedure (Ahn et al. 2012). The sand particles were in the same size range (350~400 µm diameter) and chemically modified with HCl and chlorotrimethylsilane in the same method applied to glass beads. A single water drop was released from 40 cm above the target and its impact was recorded using a high-speed video camera (976 fps). Overall, the amount of splash detachment was significantly lower (50~80%) for the beach sand than for glass beads in both hydrophobic and hydrophilic cases. However, the difference in the amount of splash detachment between hydrophobic and hydrophilic sand was 3 times larger than that of glass beads. Potential factors for lower net detachment and higher contrast, of sand compared to glass beads, might be (i) particle mobility and (ii) enhanced water repellency on rougher surfaces, respectively. Mobility experiments (angle of repose and flowability) showed that sand particles had significantly less mobility than glass beads (angle of repose: beads: 21.3 ± 0.7 °, sands: 37.3 ± 0.9 °, p < 0.001, dF = 17), and that sands took longer to flow through a funnel (beads: 1.88 ± 0.02 s, sands: 2.05 ± 0.13 s, p = 0.002, dF = 9). This lower mobility of sands may well be an important factor in the smaller amount of overall splash detachment for sands than beads. Secondly, the water repellency of hydophobized sands, measured by water contact angle (CA) and the Molarity of Ethanol Droplet test (MED), was greater than for identically hydrophobized glass beads (beads: CA 119.6 ± 5.1 °, MED 33%; sands: CA 137.0 ± 2.0 °, MED 36%). This is probably due to the enhancing effect of surface roughness on hydrophobicity. This amplified hydrophobicity can help to explain the enhanced contrast in splash behaviour between hydrophobic and hydrophilic sands. The results show that the enhanced splash detachment observed for hydrophobic model materials in our previous study occurs to an even greater degree in real sands. The findings also suggest that surface roughness and amplified hydrophobicity in real sands need to be considered when translating findings from model materials to real soils. Finally, the results of this study confirm that particle hydrophobicity leads to a greater susceptibility of sands to splash erosion in the initial stage of rain or irrigation events. References: Ahn S, et al. 2012. ESPL. DOI: 10.1002/esp.3364; Fox DM, et al. 2007. Hydro. Proc. 21: 2377-2384; Terry JP and Shakesby RA. 1993. ESPL 18: 519-25 Acknowledgement: This study has been funded by UK EPSRC (EP/H000747/1 and EP/H000704/1).

A unified approach for debugging is-a structure and mappings in networked taxonomies

PubMed Central

2013-01-01

Background With the increased use of ontologies and ontology mappings in semantically-enabled applications such as ontology-based search and data integration, the issue of detecting and repairing defects in ontologies and ontology mappings has become increasingly important. These defects can lead to wrong or incomplete results for the applications. Results We propose a unified framework for debugging the is-a structure of and mappings between taxonomies, the most used kind of ontologies. We present theory and algorithms as well as an implemented system RepOSE, that supports a domain expert in detecting and repairing missing and wrong is-a relations and mappings. We also discuss two experiments performed by domain experts: an experiment on the Anatomy ontologies from the Ontology Alignment Evaluation Initiative, and a debugging session for the Swedish National Food Agency. Conclusions Semantically-enabled applications need high quality ontologies and ontology mappings. One key aspect is the detection and removal of defects in the ontologies and ontology mappings. Our system RepOSE provides an environment that supports domain experts to deal with this issue. We have shown the usefulness of the approach in two experiments by detecting and repairing circa 200 and 30 defects, respectively. PMID:23548155

Meter-Scale Characteristics of Martian Channels and Valleys

USGS Publications Warehouse

Carr, M.H.; Malin, M.C.

2000-01-01

Mars Global Surveyor images, with resolutions as high as 1.5 m pixel, enable characterization of martian channels and valleys at resolutions one to two orders of magnitude better than was previously possible. A major surprise is the near-absence of valleys a few hundred meters wide and narrower. The almost complete absence of fine-scale valleys could be due to lack of precipitation, destruction of small valleys by erosion, or dominance of infiltration over surface runoff. V-shaped valleys with a central channel, such as Nanedi Vallis, provide compelling evidence for sustained or episodic flow of water across the surface. Larger valleys appear to have formed not by headward erosion as a consequence of groundwater sapping but by erosion from water sources upstream of the observed sections. The freshest appearing valleys have triangular cross sections, with talus from opposing walls meeting at the center of the valley. The relations suggest that the width of the valleys is controlled by the depth of incision and the angle of repose of the walls. The flat floors of less fresh-appearing valleys result primarily from later eolian fill. Several discontinuous valleys and lines of craters suggest massive subsurface solution or erosion. The climatic implications of the new images will remain obscure until the cause for the scarcity of fine-scale dissection is better understood. ?? 2000 Academic Press.

Development of modified-release tablets of zolpidem tartrate by biphasic quick/slow delivery system.

PubMed

Mahapatra, Anjan Kumar; Sameeraja, N H; Murthy, P N

2015-06-01

Zolpidem tartrate is a non-benzodiazepine analogue of imidazopyridine of sedative and hypnotic category. It has a short half-life with usual dosage regimen being 5 mg, two times a day, or 10 mg, once daily. The duration of action is considered too short in certain circumstances. Thus, it is desirable to lengthen the duration of action. The formulation design was implemented by preparing extended-release tablets of zolpidem tartrate using the biphasic delivery system technology, where sodium starch glycolate acts as a superdisintegrant in immediate-release part and hydroxypropyl methyl cellulose as a release retarding agent in extended-release core. Tablets were prepared by direct compression. Both the core and the coat contained the drug. The pre-compression blends were evaluated for angle of repose, bulk density, and compressibility index. The tablets were evaluated for thickness, hardness, weight variation test, friability, and in vitro release studies. No interaction was observed between zolpidem tartrate and excipients from the Fourier transform infrared spectroscopy and differential scanning calorimetry analysis. The results of all the formulations prepared were compared with reference product Stilnoct®. Optimized formulations showed release patterns that match the United States Pharmacopeia (USP) guidelines for zolpidem tartrate extended-release tablets. The mechanism of drug release was studied using different mathematical models, and the optimized formulation has shown Fickian diffusion. Accelerated stability studies were performed on the optimized formulation.

Flow-specific physical properties of coconut flours

NASA Astrophysics Data System (ADS)

Manikantan, Musuvadi R.; Kingsly Ambrose, Rose P.; Alavi, Sajid

2015-10-01

Coconut milk residue and virgin coconut oil cake are important co-products of virgin coconut oil that are used in the animal feed industry. Flour from these products has a number of potential human health benefits and can be used in different food formulations. The objective of this study was to find out the flow-specific physical properties of coconut flours at three moisture levels. Coconut milk residue flour with 4.53 to 8.18% moisture content (w.b.) had bulk density and tapped density of 317.37 to 312.65 and 371.44 to 377.23 kg m-3, respectively; the corresponding values for virgin coconut oil cake flour with 3.85 to 7.98% moisture content (wet basis) were 611.22 to 608.68 and 663.55 to 672.93 kg m-3, respectively. The compressibility index and Hausner ratio increased with moisture. The angle of repose increased with moisture and ranged from 34.12 to 36.20 and 21.07 to 23.82° for coconut milk residue flour and virgin coconut oil cake flour, respectively. The coefficient of static and rolling friction increased with moisture for all test surfaces, with the plywood offering more resistance to flow than other test surfaces. The results of this study will be helpful in designing handling, flow, and processing systems for coconut milk residue and virgin coconut oil cake flours.

Enhancement of the Oral Bioavailability of Fexofenadine Hydrochloride via Cremophor® El-Based Liquisolid Tablets

PubMed Central

Yehia, Soad Ali; El-Ridi, Mohamed Shafik; Tadros, Mina Ibrahim; El-Sherif, Nolwa Gamal

2015-01-01

Purpose: The current work aimed to develop promising Fexofenadine hydrochloride (FXD) liquisolid tablets able to increase its oral bioavailability and shorten time to reach maximum plasma concentrations (Tmax). Methods: Eighteen liquisolid powders were developed based on 3 variables; (i) vehicle type [Propylene glycol (PG) or Cremophor® EL (CR)], (ii) carrier [Avicel® PH102] to coat [Aerosil® 200] ratio (15, 20, 25) and (iii) FXD concentration in vehicle (30, 35, 40 %, w/w). Pre-compression studies involved identification of physicochemical interactions and FXD crystallinity (FT-IR, DSC, XRD), topographic visualization (SEM) and estimation of flow properties (angle of repose, Carr’s index, Hausner’s ratio). CR-based liquisolid powders were compressed as liquisolid tablets (LST 9 – 18) and evaluated for weight-variation, drug-content, friability-percentage, disintegration-time and drug-release. The pharmacokinetics of LST-18 was evaluated in healthy volunteers relative to Allegra® tablets. Results: Pre-compression studies confirmed FXD dispersion in vehicles, conversion to amorphous form and formation of liquisolid powders. CR-based liquisolid powders showed acceptable-to-good flow properties suitable for compaction. CR-based LSTs had appropriate physicochemical properties and short disintegration times. Release profile of LST-18 showed a complete drug release within 5 min. Conclusion: LST-18 succeeded in increasing oral FXD bioavailability by 62% and reducing Tmax to 2.16 h. PMID:26819931

Selected physico-mechanical characteristics of cryogenic and ambient ground turmeric

NASA Astrophysics Data System (ADS)

Barnwal, Pradyuman; Mohite, Ashish M.; Singh, Krishna K.; Kumar, Pankaj

2014-03-01

In this communication, selected physicomechanical characteristics of ground turmeric (cv. Prabha) were investigated for cryogenic and ambient grinding conditions of turmeric at different moisture contents (4, 6, 8 and 10% w.b.). A cryogenic grinder (Model: 100 UPZ, Hosokawa Alpine, Germany) and a micro pulverizer (hammer mill) were used for cryogenic and ambient grinding, respectively. The ground turmeric was graded in three grades viz. Gr-I, Gr-II and Gr-III with a sieve shaker using BSS Nos. 40, 85 and pan, respectively. Tap densities for cryogenic and ambient ground turmeric decreased from 678.7 (Gr-I) to 546.7 kgm-3 (Gr-III) and from 642.3 (Gr-I) to 468.6 kgm-3 (Gr-III), respectively, with the moisture increase. The angle of repose for cryogenic and ambient ground turmeric increased linearly from 26.85 (Gr-I) to 34.0° (Gr-III) and from 23.10 (Gr-I) to 28.06° (Gr-III), respectively with the increase in moisture content. The static coefficient of friction was the highest on plywood surface followed by mild steel sheet and galvanized iron sheet. The cryoground samples were found better in colour. Thermal conductivity of cryo-ground samples was higher than that of ambient ground samples. These physico-mechanical characteristics of cryogenic and ambient ground turmeric will be helpful for packaging, handling, and storage.

Effect of different drying techniques on flowability characteristics and chemical properties of natural carbohydrate-protein Gum from durian fruit seed

PubMed Central

2013-01-01

Background A natural carbohydrate biopolymer was extracted from the agricultural biomass waste (durian seed). Subsequently, the crude biopolymer was purified by using the saturated barium hydroxide to minimize the impurities. Finally, the effect of different drying techniques on the flow characteristics and functional properties of the purified biopolymer was investigated. The present study elucidated the main functional characteristics such as flow characteristics, water- and oil-holding capacity, solubility, and foaming capacity. Results In most cases except for oven drying, the bulk density decreased, thus increasing the porosity. This might be attributed to the increase in the inter-particle voids of smaller sized particles with larger contact surface areas per unit volume. The current study revealed that oven-dried gum and freeze-dried gum had the highest and lowest compressibility index, thus indicating the weakest and strongest flowability among all samples. In the present work, the freeze-dried gum showed the lowest angle of repose, bulk, tapped and true density. This indicates the highest porosity degree of freeze dried gum among dried seed gums. It also exhibited the highest solubility, and foaming capacity thus providing the most desirable functional properties and flow characteristics among all drying techniques. Conclusion The present study revealed that freeze drying among all drying techniques provided the most desirable functional properties and flow characteristics for durian seed gum. PMID:23289739

Sand-wave movement on Little Georges Bank

USGS Publications Warehouse

Twichell, David C.

1983-01-01

A 1-x-1.5-km area on Little Georges Bank (centered at 41?08?N., 68?04?W.) was mapped three times during a ten-month period by sidescan sonar and echo-sounding techniques to assess the morphology and mobility of sand waves on Georges Bank. Sand-wave amplitudes in the survey area ranged from 1-11 m although most were 5-7 m. Wavelengths were not constant as the crests were sinuous and in places, even bifurcated. The sand waves are asymmetrical with their steepest sides facing northwest; however, gradients of their steep sides mostly are 4?-10? which is well below the angle of repose for sand in water. Sand waves tended to have greater relief and a sharper asymmetry during the survey in September than during those in June or April. During the survey period the sand waves moved but the direction and rate of motion was variable. Even along an individual sand wave some parts moved as much as 60 m between surveys while other parts apparently remained stationary. The sand waves were asymmetrical, but movement was not consistently in the direction that the steep sides faced. Along the same sand wave, parts moved to the northwest while other parts moved to the southeast. Despite the complex pattern of sand motion, the mean displacement of the sand waves was below the resolution of the survey technique; to resolve it, a longer survey is needed.

Water hyacinth: a possible alternative rate retarding natural polymer used in sustained release tablet design

PubMed Central

Khatun, Sabera; Sutradhar, Kumar B.

2014-01-01

In recent years natural polymers have been widely used because of their effectiveness and availability over synthetic polymers. In this present investigation matrix tablets of Metformin hydrochloride were formulated using Water hyacinth powder and its rate retardant activity was studied. Tablets were prepared using wet granulation method with 8% starch as granulating agent and 5, 10, 15, 20, 25 and 30% of Water hyacinth powder to the drug. In preformulation study, angle of repose, Carr's Index and Hausner ratio were calculated. Fourier Transform Infrared Spectroscopy (FTIR), Differential Scanning Calorimetry (DSC), and Scanning Electron Microscopy (SEM) studies were performed and no interactions were found between drug and excipients. Weight variation, friability, hardness, thickness, diameter, and in vitro release study were performed with the prepared matrix tablets. Dissolution studies were conducted using USP type II apparatus at a speed of 100 rpm at 37°C ± 0.5 temperature for 8 h. Though all the formulations comply with both BP and USP requirements, formulation F-1 (5% of Water hyacinth) was the best fitted formula. The drug release patterns were explained in different kinetic models such as Zero order, First order, Higuchi, Hixson Crowell, and Korsmeyer-Peppas equations. The current investigation implies that Water hyacinth has the potential to be used as a rate-retarding agent in sustained release drug formulations. PMID:24966835

Lallemantia reylenne seeds as superdisintegrant: Formulation and evaluation of nimesulide orodispersible tablets

PubMed Central

Malik, Karan; Arora, Gurpreet; Singh, Inderbir; Arora, Sandeep

2011-01-01

Aim: Orodispersible tablets also known as fast dissolving tablets disintegrate instantaneously within the mouth and thus can be consumed without water. The present study was aimed to formulate orodispersible tablets of nimesulide by using Lallemantia reylenne seeds as natural superdisintegrant. Materials and Methods: Powdered lallemantia seeds were characterized for powder flow properties (bulk density, tapped density, carr's consolidation index, hausner ratio, angle of repose), swelling index, viscosity, pH, and loss on drying. The prepared tablets were evaluated for different tablet parametric tests, wetting time, water absorption ratio, effective pore radius, porosity, packing fraction, in vitro and in vivo disintegration time, in vitro dissolution and stability studies. Results and Discussion: Increase in Lallementia reylenne concentration had an appreciable effect on tablet hardness and friability which clearly indicated binding potential of the seeds. Water absorption ratio increased with increase in Lallemantia reylenne concentration from batch A1 to A4. Water uptake coupled natural polymer swelling could be the most probable mechanism for concentration dependent reduction in disintegration time by the Lallemantia reylenne seeds. Porosity of the formulated tablets was found to increase from batch A1-A4. The in vitro disintegration results were in line with in vivo disintegration results. Conclusion: It could be concluded that Lallemantia reylenne seeds could be used as natural superdisintegrant in the formulation of orodispersible tablets. PMID:23071942

What Does It Mean to Educate?

ERIC Educational Resources Information Center

Knausz, Imre

2016-01-01

This paper focuses on the most abstract and most boring question of pedagogy or, as I prefer to call my field of interest, the theory of pedagogy. My aim is to try to rehash and re-pose this question--maybe even answer it? In this regard, Ottó Mihály advises us to be careful; in the preface to his notes on the philosophy of pedagogy he asserts…

Long-Term Counterinsurgency Strategy: Maximizing Special Operations and Airpower

DTIC Science & Technology

2010-02-01

operations forces possess a repertoire of capabilities and attributes which impart them with unique strategic utility. “That utility reposes most...flashlight), LTMs are employed in a similar role to cue aircrews equipped with Night Vision Devices (NVDs). Concurrently, employment of small laptop...Special Operations Forces (PSS-SOF) and Precision Fires Image Generator (PFIG) have brought similar benefit to the employment of GPS/INS targeted weapons

Experimental simulation and morphological quantification of volcano growth

NASA Astrophysics Data System (ADS)

Grosse, Pablo; Kervyn, Matthieu; Gallland, Olivier; Delcamp, Audray; Poppe, Sam

2016-04-01

Volcanoes display very diverse morphologies as a result of a complex interplay of several constructive and destructive processes. Here the role played by the spatial distribution of eruption centre and by an underlying strike-slip fault in controlling the long term growth of volcanoes is investigated with analogue models. Volcano growth was simulated by depositing loads of granular material (sand-kaolin mixtures) from a point source. An individual load deposited at a fixed location produces a simple symmetrical cone with flank slopes at the angle of repose of the granular material (~33°) that can be considered as the building-block for the experiments. Two sets of experiments were undertaken: (1) the location of deposition of the granular material (i.e. the volcano growth location) was shifted with time following specific probability density functions simulating shifts or migrations in vent location; (2) the location of deposition was kept fixed, but the deposition rate (i.e. the volcano growth rate) was varied coupled with the movement of a basal plate attached to a step-motor simulating a strike-slip displacement under the growing cone (and hence deformation of the cone). During the progression of the experiments, the models were photographed at regular time intervals using four digital cameras positioned at slightly different angles over the models. The photographs were used to generate synthetic digital elevation models (DEMs) with 0.2 mm spatial resolution of each step of the models by applying the MICMAC digital stereo-photogrammetry software. Morphometric data were extracted from the DEMs by applying two IDL-language algorithms: NETVOLC, used to automatically calculate the volcano edifice basal outline, and MORVOLC, used to extract a set of morphometric parameters that characterize the volcano edifice in terms of size, plan shape, profile shape and slopes. Analysis of the DEM-derived morphometric parameters allows to quantitatively characterize the growth evolution of the volcano models in terms of vent distribution and growth rate-deformation rate ratios.

Hydatidose péricardique

PubMed Central

Fenane, Hicham; Maidi, El mehdi; Bouchikh, Mohamed; Lamboni, Damsane; Achir, Abdellah; Ouchen, Fahd; Oyali, Mbola; Caidi, Mohamed; Aziz, Said Al; Benosman, Abdellatif

2015-01-01

L'hydatidose est un problème de santé publique dans les pays d'endémie dont le Maghreb. L'atteinte péricardique reste rare, le diagnostic est parfois tardif à cause de la non spécificité des symptômes, et repose essentiellement sur les données de l'imagerie. Nous rapportons deux observations d'hydatidose péricardique sans atteinte cardiaque. PMID:26185566

Evaluation of United States Strategy In Central America

DTIC Science & Technology

1989-03-03

degree of tranquility and repose which it has never en - joyed even under the palmiest days of Spanish oc- cupation." William Walker was driven out of...fear and focus on Cuban/Soviet en - couragement of insurgencies miss the even greater threat that the Soviet objective for the area will bring. This... Belize , British Virgin Islands, Costa Rica, Dominica, Dominican Republic, El Salvador, Grenada, Guatemala, Haiti, Honduras, Jamaica, Montserrat

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

Wood, C.A.

Statistical relations have been determined between geometry, volume, slope, and age for 26 circum-Pacific composite (strato) volcanoes. General trends in eruption characteristics, repose periods, flow lengths and petrology are also documented. Few examples of the earliest stages of composite volcano activity are known, perhaps because these small volcanoes are indistinguishable from cinder cones. If cinder cones evolve into composite volcanoes a fundamental change in morphometry, eruption style, and petrology occurs at a basal diameter of 2 km.

La tuberculose nasosinusienne primaire: à propos d'un cas

PubMed Central

Bouchentouf, Rachid; Bouaity, Brahim; Touati, Mohamed; Benjelloun, Amine; Aitbenasser, Moulay Ali

2013-01-01

La localisation nasosinusienne de la tuberculose est rare. Elle est caractérisée par une présentation clinique polymorphe et non spécifique, posant souvent un problème de diagnostic différentiel. Le diagnostic repose sur l'examen anatomopathologique et bactériologique avec examen direct et culture. Le traitement est essentiellement médical à base d'antibacillaires. PMID:23503658

Development of Regulatory Processes in the Symbiosis Between the Sea Anemone Aiptasia pallida and its Dinoflagellate Symbionts

DTIC Science & Technology

1994-09-01

affected both dinoflagellates ( zooxanthellae ) and their hosts. Studies included the infection of algae-free hosts, responses to "host factors...34, metabolism of 15 N-ammonium and other aspects of how nitrogen was utilized by the symbiotic systems. Zooxanthellae of A. pallida showed distinct reposes to...S’ Symbiosis, zooxanthellae , dinoflagellates, sea anemones, IC i corals Unclassified Unclassified jUnclassified UL TABLE OF CONTENTS Page # Summary

Employing U.S. Navy Hospital Ships in Support of Soft Power Projection

DTIC Science & Technology

2011-03-24

the employment of hard power such as military engagements in multiple countries that support non-state actors and terrorists. One way to stem the...The United State‟s seeming decline in foreign policy can be directly attributed to the employment of hard power such as military engagements in...the Vietnam conflict, the USS REPOSE (AH-16) and USS SANCTUARY (AH-17), Haven class hospital ships, provided significant support to combat units

The Complexity Construct in Political Psychology: Personological and Cognitive Approaches

DTIC Science & Technology

2010-02-01

raisonnement et du processus de prise de décision conciliant, ouvert et reposant sur l’information. Les deux approches font appel à une analyse de...positions in order to make room for the next generation. The elderly must resign themselves to “let go” of their family domination and employment in... employment positions. This would only contribute to an adversarial relationship (albeit reversed), where resources are still not distributed with social

[Physical fingerprint for quality control of traditional Chinese medicine extract powders].

PubMed

Zhang, Yi; Xu, Bing; Sun, Fei; Wang, Xin; Zhang, Na; Shi, Xin-Yuan; Qiao, Yan-Jiang

2016-06-01

The physical properties of both raw materials and excipients are closely correlated with the quality of traditional Chinese medicine preparations in oral solid dosage forms. In this paper, based on the concept of the chemical fingerprint for quality control of traditional Chinese medicine products, the method of physical fingerprint for quality evaluation of traditional Chinese medicine extract powders was proposed. This novel physical fingerprint was built by the radar map, and consisted of five primary indexes (i.e. stackablity, homogeneity, flowability, compressibility and stability) and 12 secondary indexes (i.e. bulk density, tap density, particle size<50 μm percentage, relative homogeneity index, hausner ratio, angle of repose, powder flow time, inter-particle porosity, Carr index, cohesion index, loss on drying, hygroscopicity). Panax notoginseng saponins (PNS) extract was taken for an example. This paper introduced the application of physical fingerprint in the evaluation of source-to-source and batch-to-batch quality consistence of PNS extract powders. Moreover, the physical fingerprint of PNS was built by calculating the index of parameters, the index of parametric profile and the index of good compressibility, in order to successfully predict the compressibility of the PNS extract powder and relevant formulations containing PNS extract powder and conventional pharmaceutical excipients. The results demonstrated that the proposed method could not only provide new insights into the development and process control of traditional Chinese medicine solid dosage forms. Copyright© by the Chinese Pharmaceutical Association.

Improving the API dissolution rate during pharmaceutical hot-melt extrusion I: Effect of the API particle size, and the co-rotating, twin-screw extruder screw configuration on the API dissolution rate.

PubMed

Li, Meng; Gogos, Costas G; Ioannidis, Nicolas

2015-01-15

The dissolution rate of the active pharmaceutical ingredients in pharmaceutical hot-melt extrusion is the most critical elementary step during the extrusion of amorphous solid solutions - total dissolution has to be achieved within the short residence time in the extruder. Dissolution and dissolution rates are affected by process, material and equipment variables. In this work, we examine the effect of one of the material variables and one of the equipment variables, namely, the API particle size and extruder screw configuration on the API dissolution rate, in a co-rotating, twin-screw extruder. By rapidly removing the extruder screws from the barrel after achieving a steady state, we collected samples along the length of the extruder screws that were characterized by polarized optical microscopy (POM) and differential scanning calorimetry (DSC) to determine the amount of undissolved API. Analyses of samples indicate that reduction of particle size of the API and appropriate selection of screw design can markedly improve the dissolution rate of the API during extrusion. In addition, angle of repose measurements and light microscopy images show that the reduction of particle size of the API can improve the flowability of the physical mixture feed and the adhesiveness between its components, respectively, through dry coating of the polymer particles by the API particles. Copyright © 2014. Published by Elsevier B.V.

A systematic and mechanistic evaluation of aspartic acid as filler for directly compressed tablets containing trimethoprim and trimethoprim aspartate.

PubMed

ElShaer, Amr; Hanson, Peter; Mohammed, Afzal R

2013-04-01

The generally accepted paradigm of 'inert' and 'mono functional' excipient in dosage form has been recently challenged with the development of individual excipients capable of exhibiting multiple functions (e.g. binder-disintegrants, surfactant which affect P-gp function). The proposed study has been designed within the realm of multifunctionality and is the first and novel investigation towards evaluation of aspartic acid as a filler and disintegration enhancing agent for the delivery of biopharmaceutical class IV model drug trimethoprim. The study investigated powder characteristics using angle of repose, laser diffractometry and scanning electron microscopy (SEM). The prepared tablets were characterised using Heckel analysis, disintegration time and tensile strength measurements. Although Heckel analysis revealed that both TMP and TMP aspartate salt have high elasticity, the salt form produced a stronger compact which was attributed to the formation of agglomerates. Aspartic acid was found to have high plasticity, but its incorporation into the formulations was found to have a negative impact on the compaction properties of TMP and its salt. Surface morphology investigations showed that mechanical interlocking plays a vital role in binding TMP crystals together during compaction, while the small particle size of TMP aspartate agglomerates was found to have significant impact on the tensile strength of the tablets. The study concluded that aspartic acid can be employed as filler and disintegrant and that compactability within tablets was independent of the surface charge of the excipients. Copyright © 2012 Elsevier B.V. All rights reserved.

Extraction and Characterization of Boswellia Serrata Gum as Pharmaceutical Excipient.

PubMed

Panta, Sumedha; Malviya, Rishabha; Sharma, Pramod

2015-01-01

This manuscript deals with the purification and characterization of Boswellia serrata gum as a suspending agent. The Boswellia serrata gum was purchased as crude material, purified and further characterized in terms of organoleptic properties and further micromeritic studies were carried out to characterize the polymer as a pharmaceutical excipient. The suspending properties of the polymer were also evaluated. The results showed that the extracted gum possesses optimum organoleptic as well as micromeritic and suspending properties. To characterize Boswellia serrata gum as a natural excipient. Boswellia serrata gum, paracetamol, distilled water. The results showed that the extracted gum possesses optimum organoleptic as well as micromeritic and suspending properties. It is concluded from the research work that the gum extracted from Boswellia serrata shows the presence of carbohydrates after chemical tests. All the organoleptic properties evaluated were found to be acceptable. The pH was found to be slightly acidic. Swelling Index reveals that the gum swells well in water. Total ash value was within the limits. The values of angle of repose and Carr's Index of powdered gum powder showed that the flow property was good. IR spectra confirmed the presence of alcohol, amines, ketones, anhydrides and aromatic rings. The suspending properties of Boswellia serrata gum were found to be higher as compared to gum acacia while the flow rate of Boswellia serrata gum (1% suspension) was less than gum acacia (1% suspension). The viscosity measurement of both Boswellia serrata gum suspension and gum acacia suspension showed approximately similar results.

Comparison of ibuprofen release from minitablets and capsules containing ibuprofen: β-cyclodextrin complex.

PubMed

Salústio, P J; Cabral-Marques, H M; Costa, P C; Pinto, J F

2011-05-01

Mixtures containing ibuprofen (IB) complexed with β-cyclodextrin (βCD) obtained by two complexation methods [suspension/solution (with water removed by air stream, spray- and freeze-drying) and kneading technique] were processed into pharmaceutical dosage forms (minitablets and capsules). Powders (IB, βCD and IBβCD) were characterized for moisture content, densities (true and bulk), angle of repose and Carr's index, X-ray and NMR. From physical mixtures and IBβCD complexes without other excipients were prepared 2.5-mm-diameter minitablets and capsules. Minitablets were characterized for the energy of compaction, tensile strength, friability, density and IB release (at pH 1.0 and 7.2), whereby capsules were characterized for IB release. The results from the release of IB were analyzed using different parameters, namely, the similarity factor (f(2)), the dissolution efficiency (DE) and the amounts released at a certain time (30, 60 and 180 min) and compared statistically (α=0.05). The release of IB from the minitablets showed no dependency on the amount of water used in the formation of the complexes. Differences were due to the compaction force used or the presence of a shell for the capsules. The differences observed were mostly due to the characteristics of the particles (dependent on the method considered on the formation of the complexes) and neither to the dosage form nor to the complex of the IB. Copyright © 2011 Elsevier B.V. All rights reserved.

Pharmaceutical suspension containing both immediate/sustained-release amoxicillin-loaded gelatin nanoparticles: preparation and in vitro characterization.

PubMed

Harsha, Sree

2013-01-01

Pharmaceutical suspension containing oral dosage forms delivering both immediate-release and sustained-release amoxicillin was developed as a new dosage form to eradicate Helicobacter pylori. Amoxicillin-loaded gelatin nanoparticles are able to bind with the mucosal membrane after delivery to the stomach and could escalate the effectiveness of a drug, providing dual release. The objective of this study was to develop amoxicillin nanoparticles using innovative new technology--the Büchi Nano Spray Dryer B-90 - and investigate such features as drug content, particle morphology, yield, in vitro release, flow properties, and stability. The nanoparticles had an average particle size of 571 nm. The drug content and percentage yield was 89.2% ± 0.5% and 93.3% ± 0.6%, respectively. Angle of repose of nanoparticle suspension was 26.3° and bulk density was 0.59 g/cm(3). In vitro drug release of formulations was best fitted by first-order and Peppas models with R (2) of 0.9841 and 0.9837 respectively; release profile was 15.9%, while; for the original drug, amoxicillin, under the same conditions, 90% was released in the first 30 minutes. The nanoparticles used in this study enabled sustained release of amoxicillin over an extended period of time, up to 12 hours, and were stable for 12 months under accelerated storage conditions of 25 °C ± 2 °C and 60% ± 5% relative humidity.

Sediment Transport and Slope Stability of Ship Shoal Borrow Areas for Coastal Restoration of Louisiana

NASA Astrophysics Data System (ADS)

Liu, H.; Xu, K.; Bentley, S. J.; Li, C.; Miner, M. D.; Wilson, C.; Xue, Z.

2017-12-01

Sandy barrier islands along Louisiana coast are degrading rapidly due to both natural and anthropogenic factors. Ship Shoal is one of the largest offshore sand resources, and has been used as a borrow area for Caminada Headland Restoration Project. Our knowledge of sediment transport and infilling processes in this new sandy and dynamic borrow area is rather limited. High resolution sub-bottom seismic data, side scan sonar images, multi-beam bathymetry and laser sediment grain size data were used to study seafloor morphological evolution and pit wall stability in response to both physical and geological processes. The multi-beam bathymetry and seismic profiling inside the pit showed that disequilibrium conditions led to rapid infilling in the pits at the beginning, but this process slowed down after the pit slope became stable and topography became smooth. We hypothesize that the erosion of the adjacent seabed sediment by energetic waves and longshore currents, the supply of suspended sediment from the rivers, and the erodible materials produced by local mass wasting on pit walls are three main types of infilling sediments. Compared with mud-capped dredge pits, this sandy dredge pit seems to have more gentle slopes on pit walls, which might be controlled by the angle of repose. Infilling sediment seems to be dominantly sandy, with some mud patches on bathymetric depressions. This study helps us better understand the impacts of mining sediment for coastal restoration and improves sand resource management efforts.

Cost-effectiveness of insulin pumps compared with multiple daily injections both provided with structured education for adults with type 1 diabetes: a health economic analysis of the Relative Effectiveness of Pumps over Structured Education (REPOSE) randomised controlled trial.

PubMed

Pollard, Daniel John; Brennan, Alan; Dixon, Simon; Waugh, Norman; Elliott, Jackie; Heller, Simon; Lee, Ellen; Campbell, Michael; Basarir, Hasan; White, David

2018-04-07

To assess the long-term cost-effectiveness of insulin pumps and Dose Adjustment for Normal Eating (pumps+DAFNE) compared with multiple daily insulin injections and DAFNE (MDI+DAFNE) for adults with type 1 diabetes mellitus (T1DM) in the UK. We undertook a cost-utility analysis using the Sheffield Type 1 Diabetes Policy Model and data from the Relative Effectiveness of Pumps over Structured Education (REPOSE) trial to estimate the lifetime incidence of diabetic complications, intervention-based resource use and associated effects on costs and quality-adjusted life years (QALYs). All economic analyses took a National Health Service and personal social services perspective and discounted costs and QALYs at 3.5% per annum. A probabilistic sensitivity analysis was performed on the base case. Further uncertainties in the cost of pumps and the evidence used to inform the model were explored using scenario analyses. Eight diabetes centres in England and Scotland. Adults with T1DM who were eligible to receive a structured education course and did not have a strong clinical indication or a preference for a pump. Pumps+DAFNE. MDI+DAFNE. Incremental costs, incremental QALYs gained and incremental cost-effectiveness ratios (ICERs). Compared with MDI+DAFNE, pumps+DAFNE was associated with an incremental discounted lifetime cost of +£18 853 (95% CI £6175 to £31 645) and a gain in discounted lifetime QALYs of +0.13 (95% CI -0.70 to +0.96). The base case mean ICER was £142 195 per QALY gained. The probability of pump+DAFNE being cost-effective using a cost-effectiveness threshold of £20 000 per QALY gained was 14.0%. All scenario and subgroup analyses examined indicated that the ICER was unlikely to fall below £30 000 per QALY gained. Our analysis of the REPOSE data suggests that routine use of pumps in adults without an immediate clinical need for a pump, as identified by National Institute for Health and Care Excellence, would not be cost-effective. ISRCTN61215213. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

Multi-criteria correlation of tephra deposits to source centres applied in the Auckland Volcanic Field, New Zealand

NASA Astrophysics Data System (ADS)

Hopkins, Jenni L.; Wilson, Colin J. N.; Millet, Marc-Alban; Leonard, Graham S.; Timm, Christian; McGee, Lucy E.; Smith, Ian E. M.; Smith, Euan G. C.

2017-07-01

Linking tephras back to their source centre(s) in volcanic fields is crucial not only to reconstruct the eruptive history of the volcanic field but also to understand tephra dispersal patterns and thus the potential hazards posed by a future eruption. Here we present a multi-disciplinary approach to correlate distal basaltic tephra deposits from the Auckland Volcanic Field (AVF) to their source centres using proximal whole-rock geochemical signatures. In order to achieve these correlations, major and trace element tephra-derived glass compositions are compared with published and newly obtained whole-rock geochemical data for the entire field. The results show that incompatible trace element ratios (e.g. (Gd/Yb)N, (La/Yb)N, (Zr/Yb)N) vary widely across the AVF (e.g. (La/Yb)N = 5 to 40) but show a more restricted range within samples from a single volcanic centre (e.g. (La/Yb)N = 5 to 10). These ratios are also the least affected by fractional crystallisation and are therefore the most appropriate geochemical tools for correlation between tephra and whole-rock samples. However, findings for the AVF suggest that each volcanic centre does not have a unique geochemical signature in the field as a whole, thus preventing unambiguous correlation of tephras to source centre using geochemistry alone. A number of additional criteria are therefore combined to further constrain the source centres of the distal tephras including age, eruption scale, and location (of centres, and sites where tephra were sampled). The combination of tephrostratigraphy, 40Ar/39Ar dating and morphostratigraphic constraints allow, for the first time, the relative and absolute ordering of 48 of 53 volcanic centres of the Auckland Volcanic Field to be resolved. Eruption frequencies are shown to vary between 0.13 and 1.5 eruptions/kyr and repose periods between individual eruptions vary from <0.1 to 13 kyr, with 23 of the 48 centres shown to have pre-eruptive repose periods of <1000 years. No spatial evolutionary trends are noted, although a relationship between short repose periods and closely spaced eruption locations is identified for a number of centres. In addition, no temporal-geochemical trends are noted, but a relationship between geochemical signature and eruption volume is highlighted.

Acoustic-Liner Admittance in a Duct

NASA Technical Reports Server (NTRS)

Watson, W. R.

1986-01-01

Method calculates admittance from easily obtainable values. New method for calculating acoustic-liner admittance in rectangular duct with grazing flow based on finite-element discretization of acoustic field and reposing of unknown admittance value as linear eigenvalue problem on admittance value. Problem solved by Gaussian elimination. Unlike existing methods, present method extendable to mean flows with two-dimensional boundary layers as well. In presence of shear, results of method compared well with results of Runge-Kutta integration technique.

The long winter model of Martian biology: A speculation

NASA Technical Reports Server (NTRS)

Sagan, C.

1971-01-01

An estimated mean thickness of about 1 km of frost in the Martian north polar cap summer remnant, if vaporized, would yield about 1000 g/sq cm of atmosphere over the planet, higher global temperatures through the greenhouse effect, and a greatly increased likelihood of liquid water. Vaporization of such cap remnants may occur twice each equinoctial precession, and Martian organisms may now be in cryptobiotic repose awaiting the end of the long precessional winter. The Viking biology experiments can test this hypothesis.

Installation Restoration Program. Operable Unit B1 Remedial Investigation/Feasibility Study. Appendices

DTIC Science & Technology

1993-06-30

agency (California Health and Safety Code [H&SC], Section 25179.6[a][2]). 1.2.5 Porter-Cologne Water Quality Act and Related Policies The Porter-Cologne...which endangers the comfort, repose, and health and safety of the public. SMAQMD Rule 403 requires that all reasonable precautions be taken not to cause...concentration values on Figures C-1 through C-IO. Differences in soil physical parameters, listed in Table C-2 for different compounds were questiotned

Plasmocytome cutané secondaire révélant un myélome multiple: à propos d'un cas

PubMed Central

Ngolet, Lydie Ocini; N'soundhat, Norbert Lamini; Ndounga, Eliane; Kocko, Innocent; Kidédé, Daphtone Chabel Nkouala; Ntsiba, Honoré

2016-01-01

Le plasmocytome cutané secondaire métastatique est une prolifération plasmocytaire multiple extramédullaire de localisation cutanée. Son diagnostic repose sur la mise en évidence d'une prolifération plasmocytaire maligne au niveau médullaire et cutané. Son apparition s'associe à un stade avancé du myélome et à un pronostic péjoratif. PMID:27642385

L'optique pour la sécurité sanitaire des aliments

NASA Astrophysics Data System (ADS)

Piat, Félix

2017-12-01

Il semble aujourd'hui évident que chaque produit alimentaire commercialisé ne représente aucun danger pour la santé. Cet acquis repose pourtant sur un système complexe de règles et de contrôles appliqués quotidiennement dans les coulisses de l'industrie agro-alimentaire. Les technologies optiques y jouent un rôle prépondérant, permettant de séparer le bon grain de l'ivraie.

A new visually evoked cerebral blood flow response analysis using a low-frequency estimation.

PubMed

Rey, Beatriz; Naranjo, Valery; Parkhutik, Vera; Tembl, José; Alcañiz, Mariano

2010-03-01

Transcranial Doppler (TCD) has been widely used to monitor cerebral blood flow velocity (BFV) during the performance of cognitive tasks compared with repose periods. Although one of its main advantages is its high temporal resolution, only some of the previous functional TCD studies have focused on the analysis of the temporal evolution of the BFV signal and none of them has performed a spectral analysis of the signal. In this study, maximum BFV data in both posterior cerebral arteries was monitored during a visual perception task (10 cycles of alternating darkness and illumination) for 23 subjects. A peak was located in the low-frequency band of the spectrum of the maximum BFV of each subject both during visual stimulation and repose periods. The frequency of this peak was in the range between 0.037 and 0.098Hz, depending on the subject, the vessel and the experimental condition. The component of the signal at this frequency, which is associated with the slow variations caused by the visual stimuli, was estimated. That way, the variations in BFV caused by the experimental stimuli were isolated from the variations caused by other factors. This low-frequency estimation signal was used to obtain parameters about the temporal evolution and the magnitude variations of the BFV in a reliable way, thus, characterizing the neurovascular coupling of the participants. Copyright 2010 World Federation for Ultrasound in Medicine & Biology. Published by Elsevier Inc. All rights reserved.

National-level long-term eruption forecasts by expert elicitation

NASA Astrophysics Data System (ADS)

Bebbington, Mark S.; Stirling, Mark W.; Cronin, Shane; Wang, Ting; Jolly, Gill

2018-06-01

Volcanic hazard estimation is becoming increasingly quantitative, creating the potential for land-use decisions and engineering design to use volcanic information in an analogous manner to seismic codes. The initial requirement is to characterize the possible hazard sources, quantifying the likely timing, magnitude and location of the next eruption in each case. This is complicated by the extremely different driving processes at individual volcanoes, and incomplete and uneven records of past activity at various volcanoes. To address these issues, we carried out an expert elicitation approach to estimate future eruption potential for 12 volcanoes of interest in New Zealand. A total of 28 New Zealand experts provided estimates that were combined using Cooke's classical method to arrive at a hazard estimate. In 11 of the 12 cases, the elicited eruption duration increased with VEI, and was correlated with expected repose, differing little between volcanoes. Most of the andesitic volcanoes had very similar elicited distributions for the VEI of a future eruption, except that Taranaki was expected to produce a larger eruption, due to the current long repose. Elicited future vent locations for Tongariro and Okataina reflect strongly the most recent eruptions. In the poorly studied Bay of Islands volcanic field, the estimated vent location distribution was centred on the centroid of the previous vent locations, while in the Auckland field, it was focused on regions within the field without past eruptions. The elicited median dates for the next eruptions ranged from AD2022 (Whakaari/White Island) to AD4390 (Tuhua/Mayor Island).

A Comparative Study on Cancer Prevention Principles Between Iranian Traditional Medicine and Classic Medicine

PubMed Central

Zeinalian, Mehrdad; Eshaghi, Mehdi; Sharbafchi, Mohammad Reza; Naji, Homayoun; Marandi, Sayed Mohammad Masoud; Asgary, Sedigheh

2016-01-01

Cancer is one of the three main causes of mortality in most human communities whose prevalence is being increased. A significant part of health budget in all countries has been allocated to treat the cancer, which is incurable in many cases. It has led the global health attitude to cancer prevention. Many cancer-related risk factors have been identified for which preventive recommendations have been offered by international organizations such as World Health Organization. Some of the most important of these risk factors are smoking and alcohol consumption, hypercaloric and low-fiber diet, obesity, inactivity, environmental and industrial pollution, some viral infections, and hereditary factors. Exact reviewing of Iranian-Islamic traditional medicine (IITM) resources determines that preventive rules, which named as six essential rules (Sitteh-e-Zarurieah) are abundantly found, including all identified cancer-related risk factors. These preventive rules are: Air (Hava), body movement and repose, sleep and wakefulness, food and drink, evacuation and retention, and mental movement and repose (A’raz-e-Nafsani). The associated risk factors in classic medicine are: Smoking and air pollution, sedentary life, sleep disturbance, improper nutrition and alcohol, chronic constipation, and psychoneurotic stresses. Moreover, these rules are comprehensive enough to include many of the other harmful health-related factors whose roles have been confirmed in the occurrence of different diseases, except cancer. Apparently, cancer prevention in Iran would be more successful if the sextet necessary rules of IITM are promoted among the populations and health policy makers. PMID:27141280

Design, Formulation, and Physicochemical Evaluation of Montelukast Orally Disintegrating Tablet

PubMed Central

Aslani, Abolfazl; Beigi, Maryam

2016-01-01

Background: Orally disintegrating tablets (ODTs) are a modern form of tablets that when placed in the oral cavity, disperses rapidly. These tablets have advantages, particularly good applications for children and old patients who have a complication in chewing or swallowing solid dosage forms. The aim of this study was to design, formulate, and evaluate the physicochemical properties of 5 mg montelukast ODTs for the prevention of asthma and seasonal allergies. Methods: Formulations were prepared with different amounts of super disintegrating agents and effervescent bases as disintegrant agents. Flowability and compressibility of mixed powders were evaluated. The prepared formulations were tested for hardness, thickness, friability, weight variation, drug content, wetting time, disintegration time, dissolution study, and moisture uptake studies. Results: The compressibility index and angle of repose were in the range of 15.87%–23.43% and 32.93–34.65, respectively. Hardness, thickness, friability, wetting time, and content uniformity of formulations were in the range of 33.7–37.1 N, 3.00–3.81 mm, 0.27%–0.43%, 31–50 s and 96.28%–99.90%, respectively. Disintegration time of the tablets prepared with super disintegrating agents, effervescent bases, and combination of two were in the range of 30–50, more than 60 and 20–36 s, respectively. Conclusions: Mixture of powders and tablets passed all the specified tests. The results showed formulations prepared by super disintegrating agents and super disintegrating agents with effervescent bases had shorter disintegration time compared to formulations with effervescent bases alone. PMID:27857833

Granular avalanches on the Moon: Mass-wasting conditions, processes, and features

NASA Astrophysics Data System (ADS)

Kokelaar, B. P.; Bahia, R. S.; Joy, K. H.; Viroulet, S.; Gray, J. M. N. T.

2017-09-01

Seven lunar crater sites of granular avalanches are studied utilizing high-resolution images (0.42-1.3 m/pixel) from the Lunar Reconnaissance Orbiter Camera; one, in Kepler crater, is examined in detail. All the sites are slopes of debris extensively aggraded by frictional freezing at their dynamic angle of repose, four in craters formed in basaltic mare and three in the anorthositic highlands. Diverse styles of mass wasting occur, and three types of dry-debris flow deposit are recognized: (1) multiple channel-and-lobe type, with coarse-grained levees and lobate terminations that impound finer debris, (2) single-surge polylobate type, with subparallel arrays of lobes and fingers with segregated coarse-grained margins, and (3) multiple-ribbon type, with tracks reflecting reworked substrate, minor levees, and no coarse terminations. The latter type results from propagation of granular erosion-deposition waves down slopes dominantly of fine regolith, and it is the first recognized natural example. Dimensions, architectures, and granular segregation styles of the two coarse-grained deposit types are like those formed in natural and experimental avalanches on Earth, although the timescale of motion differs due to the reduced gravity. Influences of reduced gravity and fine-grained regolith on dynamics of granular flow and deposition appear slight, but we distinguish, for the first time, extensive remobilization of coarse talus by inundation with finer debris. The (few) sites show no clear difference attributable to the contrasting mare basalt and highland megaregolith host rocks and their fragmentation. This lunar study offers a benchmarking of deposit types that can be attributed to formation without influence of liquid or gas.

The risk of recrystallization: changes to the toxicity and morphology of pyrimethamine.

PubMed

Perold, Zak; Caira, Mino R; Brits, Marius

2014-01-01

Pyrimethamine, an anti-malarial agent known to exhibit solid state polymorphism, may be purified by means of recrystallization. Recrystallization may alter the solid state chemistry of pharmaceuticals, which may impact the toxicity and/or manufacturability thereof. We evaluated the risks associated with the recrystallization of pyrimethamine. Pyrimethamine was recrystallized using several organic solvents. X-ray diffraction, thermal analysis, infra-red spectroscopy, microscopy, flowability -, solubility and dissolution testing as well as computational work were employed to evaluate the recrystallized products. A toxic solvatomorph of pyrimethamine (Pyr-MeOH) was found to be the product from methanol recrystallization. The elucidation of - and the elaboration on the unique characteristics of Pyr-MeOH provides the pharmaceutical industry with several means to identify Pyr-MeOH and to distinguish it from the pharmaceutically preferred anhydrous form (Pyr). Thermal methods of analysis found that the toxicity of Pyr-MeOH may be reversed by overcoming a desolvation activation energy of 148 kJ/mol. In addition it was found that recrystallization altered the morphology of Pyr. Angle of repose and tapped density determinations identified that the different morphologies of Pyr displayed differences in powder flow and compressibility behaviour and In Silico calculations were successful in rendering morphologies resembling that found experimentally. We present a solvatomorph of pyrimethamine and provide several characteristic means to identify this unwanted toxic form and quantified the energy required to overcome its toxicity. In addition we describe that Pyr may present in different morphologies and show how it may impact the manufacturability thereof.

Effect of superfine grinding on the physico-chemical, morphological and thermogravimetric properties of Lentinus edodes mushroom powders.

PubMed

Ming, Jian; Chen, Long; Hong, Hui; Li, Jinlong

2015-09-01

Lentinus edodes is an edible mushroom commonly known as shiitake, which is the second most produced and consumed edible mushroom in the world and is an important nutrient source in the human diet. To fully use L. edodes, the mushrooms are occasionally ground into powder as a flavourful and functional food additive. This study produces powders from the cap and stipe of Lentinus edodes mushrooms through superfine grinding. These powders are composed of sub-micron range particles with various size distributions. The superfine grinding process is then compared with shear pulverisation to determine the different effects on both the cap and stipe powders in terms of particle size and physico-chemical, morphological and thermogravimetric properties. When average particle size was reduced to 0.54 and 0.46 µm, respectively, the moisture and protein content, angles of repose and slide, and water holding capacity of the powders decreased to varied extents. However, soluble dietary fibre, water solubility index, and swelling capacity increased. Scanning electron microscope images suggested that the superfine grinding process effectively changed the original surface structure of the L. edodes powders. The curves of thermogravimetric analysis and those of the derivatives of thermogravimetry indicated that superfine grinding can improve the thermostability of L. edodes powders. Furthermore, superfinely ground L. edodes powders may be used as pharmaceutical or food additives in various fields. The present study suggests that superfinely ground L. edodes powders may be applied in various fields as pharmaceutical or food additives. © 2014 Society of Chemical Industry.

Enhancement of solubility and bioavailability of ambrisentan by solid dispersion using Daucus carota as a drug carrier: formulation, characterization, in vitro, and in vivo study.

PubMed

Deshmane, Subhash; Deshmane, Snehal; Shelke, Santosh; Biyani, Kailash

2018-06-01

Ambrisentan is an US FDA approved drug, it is the second oral endothelin A receptor antagonist known for the treatment of pulmonary arterial hypertension, but its oral administration is limited due to its poor water solubility. Hence, the objective of the investigation was focused on enhancement of solubility and bioavailability of ambrisentan by solid dispersion technique using natural Daucus carota extract as drug carrier. Drug carrier was evaluated for solubility, swelling index, viscosity, angle of repose, hydration capacity, and acute toxicity test (LD 50 ). Ambrisentan was studied for the saturation solubility, phase solubility, and Gibbs free energy change. Compatibility of drug and the natural carrier was confirmed by DSC, FTIR, and XRD. Solid dispersions were evaluated for drug content, solubility, morphology, in vitro, and in vivo study. Screening of the natural carrier showed the desirable properties like water solubility, less swelling index, less viscosity, and acute toxicity study revealed no any clinical symptoms of toxicity. Drug and carrier interaction study confirmed the compatibility to consider its use in the formulation. Formed particles were found to be spherical with smooth surface. In vitro studies revealed higher drug release from the solid dispersion than that of the physical mixture. Bioavailability study confirms the increased absorption and bioavailability by oral administration of solid dispersion. Hence, it can be concluded that the natural Daucus carota extract can be the better alternative source for the preparation of solid dispersion and/or other dosage forms for improving solubility and bioavailability.

Development of a binary carrier system consisting polyethylene glycol 4000 - ethyl cellulose for ibuprofen solid dispersion

PubMed Central

Alagdar, Gada Sulaiman A.; Oo, May Kyaw; Sengupta, Pinaki; Mandal, Uttam Kumar; Jaffri, Julian Md.; Chatterjee, Bappaditya

2017-01-01

Background and Objective: One of the established strategies to improve solubility and dissolution rate of poorly water-soluble drugs is solid dispersion (SD). Polyethylene glycol (PEG) is used as common carrier despite its stability problem which may be overcome by the addition of hydrophobic polymer. The present research aimed to develop an SD formulation with ibuprofen, a poor water-soluble BCS Class II drug as active pharmaceutical ingredient (API) and PEG 4000-ethyl cellulose (EC) as binary carrier. Methods: Melt mixing SD method was employed using a ratio of API: binary carrier (1:3.5 w/w) (SDPE). Another SD was prepared using only PEG (SDP) as a carrier for comparative study. The developed formulation was evaluated using optical microscopy, scanning electron microscopy (SEM), determination of moisture content, differential scanning calorimetry (DSC), in vitro dissolution test, attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR) and flow properties. Results: SEM and DSC indicated the conversion of crystalline ibuprofen to fine partly amorphous solid dispersion, which was responsible for the increase in dissolution rate of SD than a physical mixture. The release characteristics within 1 h from the higher to the lower value were the SDPE> SDP> physical mixture. Flow property evaluation using the angle of repose showed no difference between SD and PM. However, by Carr index and Hausner ratio, the flow properties of SDPE was excellent. Conclusion: The SD formulation with the PEG 4000-EC carrier can be effective to enhance in vitro dissolution of ibuprofen immediate release dosage form. PMID:29184827

Design of gefitinib-loaded poly (l-lactic acid) microspheres via a supercritical anti-solvent process for dry powder inhalation.

PubMed

Lin, Qing; Liu, Guijin; Zhao, Ziyi; Wei, Dongwei; Pang, Jiafeng; Jiang, Yanbin

2017-10-30

To develop a safer, more stable and potent formulation of gefitinib (GFB), micro-spheres of GFB encapsulated into poly (l-lactic acid) (PLLA) have been prepared by supercritical anti-solvent (SAS) technology in this study. Operating factors were optimized using a selected OA 16 (4 5 ) orthogonal array design, and the properties of the raw material and SAS processed samples were characterized by different methods The results show that the GFB-loaded PLLA particles prepared were spherical, having a smaller and narrower particle size compared with raw GFB. The optimal GFB-loaded PLLA sample was prepared with less aggregation, highest GFB loading (15.82%) and smaller size (D 50 =2.48μm, which meets the size of dry powder inhalers). The results of XRD and DSC indicate that GFB is encapsulated into PLLA matrix in a polymorphic form different from raw GFB. FT-IR results show that the chemical structure of GFB does not change after the SAS process. The results of in vitro release show that the optimal sample release was slower compared with raw GFB particles. Moreover, the results of in vitro anti-cancer trials show that the optimal sample had a higher cytotoxicity than raw GFB. After blending with sieved lactose, the flowability and aerosolization performance of the optimal sample for DPI were improved, with angle of repose, emitted dose and fine particles fractions from 38.4° to 23°, 63.21% to >90%, 23.37% to >30%, respectively. Copyright © 2017 Elsevier B.V. All rights reserved.

The Role of Source Material in Basin Sedimentation, as Illustrated within Eureka Valley, Death Valley National Park, CA.

NASA Astrophysics Data System (ADS)

Lawson, M. J.; Yin, A.; Rhodes, E. J.

2015-12-01

Steep landscapes are known to provide sediment to sink regions, but often petrological factors can dominate basin sedimentation. Within Eureka Valley, in northwestern Death Valley National Park, normal faulting has exposed a steep cliff face on the western margin of the Last Chance range with four kilometers of vertical relief from the valley floor and an angle of repose of nearly 38 degrees. The cliff face is composed of Cambrian limestone and dolomite, including the Bonanza King, Carrara and Wood Canyon formations. Interacting with local normal faulting, these units preferentially break off the cliff face in coherent blocks, which result in landslide deposits rather than as finer grained material found within the basin. The valley is well known for a large sand dune, which derives its sediment from distal sources to the north, instead of from the adjacent Last Chance Range cliff face. During the Holocene, sediment is sourced primary from the northerly Willow Wash and Cucomungo canyon, a relatively small drainage (less than 80 km2) within the Sylvan Mountains. Within this drainage, the Jurassic quartz monzonite of Beer Creek is heavily fractured due to motion of the Fish Valley Lake - Death Valley fault zone. Thus, the quartz monzonite is more easily eroded than the well-consolidated limestone and dolomite that forms the Last Change Range cliff face. As well, the resultant eroded material is smaller grained, and thus more easily transported than the limestone. Consequently, this work highlights an excellent example of the strong influence that source material can have on basin sedimentation.

Sedimentary processes of the Bagnold Dunes: Implications for the eolian rock record of Mars

NASA Astrophysics Data System (ADS)

Ewing, R. C.; Lapotre, M. G. A.; Lewis, K. W.; Day, M.; Stein, N.; Rubin, D. M.; Sullivan, R.; Banham, S.; Lamb, M. P.; Bridges, N. T.; Gupta, S.; Fischer, W. W.

2017-12-01

The Mars Science Laboratory rover Curiosity visited two active wind-blown sand dunes within Gale crater, Mars, which provided the first ground-based opportunity to compare Martian and terrestrial eolian dune sedimentary processes and study a modern analog for the Martian eolian rock record. Orbital and rover images of these dunes reveal terrestrial-like and uniquely Martian processes. The presence of grainfall, grainflow, and impact ripples resembled terrestrial dunes. Impact ripples were present on all dune slopes and had a size and shape similar to their terrestrial counterpart. Grainfall and grainflow occurred on dune and large-ripple lee slopes. Lee slopes were 29° where grainflows were present and 33° where grainfall was present. These slopes are interpreted as the dynamic and static angles of repose, respectively. Grain size measured on an undisturbed impact ripple ranges between 50 μm and 350 μm with an intermediate axis mean size of 113 μm (median: 103 μm). Dissimilar to dune eolian processes on Earth, large, meter-scale ripples were present on all dune slopes. Large ripples had nearly symmetric to strongly asymmetric topographic profiles and heights ranging between 12 cm and 28 cm. The composite observations of the modern sedimentary processes highlight that the Martian eolian rock record is likely different from its terrestrial counterpart because of the large ripples, which are expected to engender a unique scale of cross stratification. More broadly, however, in the Bagnold Dune Field as on Earth, dune-field pattern dynamics and basin-scale boundary conditions will dictate the style and distribution of sedimentary processes.

Ocimum Sanctum seeds, a natural superdisintegrant: formulation and evaluation of fast melt tablets of nimesulide.

PubMed

Malik, Karan; Arora, Gurpreet; Singh, Inderbir

2012-01-01

Fast melt tablets, also known as fast dissolving tablets, disintegrate instantaneously within the mouth and thus can be consumed without water. The present study was aimed to formulate fast melt tablets of nimesulide by using Ocimum Sanctum seeds as a natural tablet superdisintegrant. Powdered Ocimum seeds were characterized for powder flow properties (bulk density, tapped density, Carr's consolidation index, Hausner ratio, angle of repose), swelling index, viscosity, pH, loss on drying and microbial load. The prepared tablets were evaluated for different tablet parametric tests, wetting time, water absorption ratio, effective pore radius, porosity, packing fraction, in vitro and in vivo disintegration time, in-vitro dissolution and stability studies. The swelling index was evaluated to be 1600. An appreciable effect of the natural material was seen on tablet hardness and friability. The water absorption ratio increased from 56.15 +/- 0.85 to 80.76 +/- 0.70 (A1-A4). Water uptake coupled natural polymer swelling could be the most probable mechanism for concentration dependent reduction in disintegration time by the Ocimum Sanctum seeds. Porosity of the formulated tablets was found to increase from batch A1-A4. The in vitro disintegration results were in line with in vivo disintegration results. The f2 values (in comparison with Nimulid MD) of 95.90 and 93.65 were obtained with A3 and A4 batches respectively. It could be concluded that Ocimum Sanctum seeds could be used as a natural superdisintegrant in the formulation of fast melt tablets.

Torsemide Fast Dissolving Tablets: Development, Optimization Using Box-Bhenken Design and Response Surface Methodology, In Vitro Characterization, and Pharmacokinetic Assessment.

PubMed

El-Shenawy, Ahmed A; Ahmed, Mahmoud M; Mansour, Heba F; Abd El Rasoul, Saleh

2017-08-01

The present study planed to develop new fast dissolving tablets (FDTs) of torsemide. Solid dispersions (SDs) of torsemide and sorbitol (3:1) or polyvinylpyrrolidone (PVP) k25 were prepared. The prepared SDs were evaluated for in-vitro dissolution. Fourier transform infrared spectroscopy and differential scanning calorimetry for SDs revealed no drug/excipient interactions and transformation of torsemide to the amorphous form. Torsemide/sorbitol SD was selected for formulation of torsemide FDTs by direct compression method. Box-Bhenken factorial design was employed to design 15 formulations using croscarmellose sodium and crospovidone at different concentrations. The response surface methodology was used to analyze the effect of changing these concentrations (independent variables) on disintegration time (Y 1 ), percentage friability (Y 2 ), and amount torsemide released at 10 min. The physical mixtures of torsemide and the used excipients were evaluated for angle of repose, Hausner's ratio, and Carr's index. The prepared FDTs tablets were evaluated for wetting and disintegration time, weight variation, drug content, percentage friability, thickness, hardness, and in vitro release. Based on the in-vitro results and factorial design characterization, F10 and F7 were selected for bioavailability studies following administration to Albino New Zealand rabbits. They showed significantly higher C max and (AUC 0-12 ) and shorter T max than those obtained after administration of the corresponding ordinary commercial Torseretic ® tablets. Stability study was conducted for F10 that showed good stability upon storage at 30°C/75% RH and 40°C/75% RH for 3 months.

Assessment of facial golden proportions among central Indian population.

PubMed

Saurabh, Rathore; Piyush, Bolya; Sourabh, Bhatt; Preeti, Ojha; Trivedi, Rutvik; Vishnoi, Pradeep

2016-12-01

This study aimed to identify and establish the facial and smile proportions in young adults and to compare the results with ideal or divine proportions, compare the proportions of males and females included in our study population and compare them with those established for Caucasian and Japanese populations. Two hundred participants (164 females, 36 males) with Angle's class I malocclusion (M.O). and well-balanced faces were selected and photographed in the frontal repose position. Analysis was done in Adobe Photoshop software. Statistical analysis was done using the Statistical Package for the Social Sciences version 17.0. (IBM Corporation Armonk, New York, United States). Results suggested that females are more near to ideal ratios and males are more deviated from the ideal ratios. The proportions of males and females were not considerably different from each other. In Indian population, upper 3 rd facial height (TR-LC) was increased and mid-face height (LC-LN) was decreased; in lower 3 rd of the face, LN-CH was slightly increased in comparison to CH-ME. In facial widths, outer canthal width (LC-LC) was greater in the Indian population and mouth width (CH-CH) was normal. When compared with Indian population, Japanese participants had wider noses, outer canthal distance, and bitemporal width. It was concluded that significant difference was found between the proportions of the Indian population and ideal ratio. When Indian population was compared with Japanese and Caucasian populations, some parameters of facial proportions showed significant difference, which leads to the need for establishing standardized norms for various facial proportions in Indian population.

Soliton-mediated conduit flow: Deep Hawaiian magma migration

NASA Astrophysics Data System (ADS)

Ryan, M.; Stanley, B.

2006-12-01

Solitons have first-order attributes that include shape- and volume-conserving packets of fluid that migrate with characteristic wavelengths, amplitudes, wave numbers, and pulse durations. For ascent in dike-like magma- filled fractures, the soliton pulse duration is directly proportional to the conduit wall region viscosity and inversely proportional to the density contrast that drives the flow. Second-order effects that modify pathways include heat loss to conduit wall rocks, and progressive crystallization episodes along conduit walls. Long-lived (and intermediate duration) historical eruption episodes of Kilauea volcano, Hawai'i, include the 1959 Kilauea summit series at Kilauea Iki, the 1969-1974 series at Mauna Ulu and the 1983-to-present series at Pu'u `O'o-Kupaianaha. For each locale, the eruptions display a variable time-series in their erupted volumes, as well as fountain heights and vent flow rates. Inter-episode repose periods, however, often show broad regularity over extended periods. We suggest that these dynamics represent serendipitous windows into the characteristic system dynamics of deep magma migration beneath Hawai'i: all made possible by the chance clearance of mechanical obstructions allowing virtually open-system behavior. The rhythmic `beat' of eruptive episodes within a long-lived series (and their roughly regular repose periods) arise directly from the soliton migration mechanism. For non-summit locales such as Mauna Ulu and Pu'u `O'o-Kupaianaha, the fluid contents of the sub-caldera reservoir and the shallow molten rift zone core modulate the observed intrusion- eruption dynamics as volumetric displacements transmit down-rift the pressure pulses first felt beneath Halemaumau and the summit caldera. Analytic calculations of wave speed, wave length, batch volume, parcel shapes and repose periods reveal the dependence on material properties appropriate for Kilauea intrusions and eruptions. Analogue laboratory experiments using stiff mixtures of gelatin as the matrix `fluid' and dyed aqueous solutions as the injected phase, reveal that the injections exhibit soliton-like ascent modes: independent packets of fluid rise along vertical fractures with bulbous noses and slender tails that thin with depth and increasing confining pressures. Spatially-varying azimuths of principal stress components ( ) result in systematic rotations of the ascent pathway as the rising soliton rotates to reestablish an orthogonal relationship with the minimum compressive stress component ( ) orientation. These rotations in ascent pathway orientation are appropriate for the inferred transitions from the upper mantle, through the oceanic crust and into Kilauea's volcanic shield and laterally extensive East Rift Zone and Southwest Rift Zone.

Traumatisme de la main par injection a haute pression

PubMed Central

Mabchoure, K.; Diouri, M.; Bahechar, N.; Chlihi, A.

2016-01-01

Summary Les traumatismes de la main par injection à haute pression sont des accidents relativement rares et souvent mal connus par le praticien. Les lésions qui dépendent du produit injecté et du site d’injection sont pourvoyeuses de séquelles esthétiques et fonctionnelles lourdes. Le traitement repose sur la chirurgie, l’antibiothérapie et la rééducation précoce et spécifique. Nous rapportons notre expérience ainsi qu’une revue de la littérature. PMID:27857654

Smile analysis in rhinoplasty: a randomized study for comparing resection and transposition of the depressor septi nasi muscle.

PubMed

Kalantar-Hormozi, Abdoljalil; Beiraghi-Toosi, Arash

2014-02-01

The depressor septi nasi muscle is responsible for smiling deformity. Its manipulation is beneficial in patients with muscle hypertrophy. In addition, it enhances the smile and tip-lip relationship. In this study, depressor septi nasi muscle excision through a transfixion incision is compared with its transposition through an upper labial sulcus incision. Two techniques of depressor septi nasi muscle treatment were performed randomly for rhinoplasty cases. Smile analysis in rhinoplasty, consisting of measurements of nasal length, nasal diagonal, tip projection, and upper lip height, and noting transverse upper labial crease in repose and full smile, was performed on preoperative and postoperative photographs. One hundred patients were studied in two equal groups. Preoperatively, tip projection and upper lip height were decreased significantly with smiling. Generally, the effect of smiling on all five parameters was decreased significantly following rhinoplasty. The two different techniques were not significantly different in decreasing the effects of smiling on nasal length, nasal diagonal, tip projection, upper lip height, or transverse crease. The two different techniques were the same in decreasing the effects of smiling. The authors recommend smile analysis in rhinoplasty, consisting of measurement of nasal length, nasal diagonal, tip projection, and upper lip height, and noting transverse upper labial crease in repose and during smiling, before rhinoplasty for preoperative evaluation and after the operation for outcome assessment. Depressor septi nasi muscle treatment should be considered if a decrease in tip projection or upper lip height with smiling or a transverse upper labial crease during smiling is extraordinary or unsightly. Therapeutic, II.

Influence of Polymer Type on the Physical Properties and Release Profile of Papaverine Hydrochloride From Hard Gelatin Capsules.

PubMed

Polski, Andrzej; Iwaniak, Karol; Kasperek, Regina; Modrzewska, Joanna; Sobótka-Polska, Karolina; Sławińska, Karolina; Poleszak, Ewa

2015-01-01

The capsule is one of the most important solid dosage forms in the pharmaceutical industry. It is easier and faster to produce than a tablet, because it requires fewer excipients. Generally, capsules are easy to swallow and mask any unpleasant taste of the substances used while their release profiles can be easily modified. Papaverine hydrochloride was used as a model substance to show different release profiles using different excipients. The main aim of the study was to analyze the impact of using different polymers on the release profile of papaverine hydrochloride from hard gelatin capsules. Six series of hard gelatin capsules containing papaverine hydrochloride as a model drug and different excipients were made. Then, the angle of repose, flow rate, mass flow rate and volume flow rate of the powders used for capsule production were analyzed. The uniform weight and disintegration time of the capsules were studied. The dissolution study was performed in a basket apparatus, while the amount of papaverine hydrochloride released was determined spectrophotometrically at 251 nm. Only one formula of powder had satisfactory flow properties, while all formulas had good Hausner ratios. The best properties were from powder containing polyvinylpyrrolidone 10k. The disintegration time of capsules varied from 1:30 min to 2:00 min. As required by Polish Pharmacopoeia X, 80% of the active substance in all cases was released within 15 minutes. The capsules with polyvinylpyrrolidone 10k were characterized by the longest release. On the other hand, capsules containing microcrystalline cellulose had the fastest release profile. Using 10% of different polymers, without changing the other excipients, had a significant impact on the physical properties of the powders and papaverine hydrochloride release profile. The two most preferred capsule formulations contained either polyvinylpyrrolidone 10k or microcrystalline cellulose.

Roller compaction of moist pharmaceutical powders.

PubMed

Wu, C-Y; Hung, W-L; Miguélez-Morán, A M; Gururajan, B; Seville, J P K

2010-05-31

The compression behaviour of powders during roller compaction is dominated by a number of factors, such as process conditions (roll speed, roll gap, feeding mechanisms and feeding speed) and powder properties (particle size, shape, moisture content). The moisture content affects the powder properties, such as the flowability and cohesion, but it is not clear how the moisture content will influence the powder compression behaviour during roller compaction. In this study, the effect of moisture contents on roller compaction behaviour of microcrystalline cellulose (MCC, Avicel PH102) was investigated experimentally. MCC samples of different moisture contents were prepared by mixing as-received MCC powder with different amount of water that was sprayed onto the powder bed being agitated in a rotary mixer. The flowability of these samples were evaluated in terms of the poured angle of repose and flow functions. The moist powders were then compacted using the instrumented roller compactor developed at the University of Birmingham. The flow and compression behaviour during roller compaction and the properties of produced ribbons were examined. It has been found that, as the moisture content increases, the flowability of moist MCC powders decreases and the powder becomes more cohesive. As a consequence of non-uniform flow of powder into the compaction zone induced by the friction between powder and side cheek plates, all produced ribbons have a higher density in the middle and lower densities at the edges. For the ribbons made of powders with high moisture contents, different hydration states across the ribbon width were also identified from SEM images. Moreover, it was interesting to find that these ribbons were split into two halves. This is attributed to the reduction in the mechanical strength of moist powder compacts with high moisture contents produced at high compression pressures. Copyright (c) 2010 Elsevier B.V. All rights reserved.

Eros is a Rubble Pile

NASA Astrophysics Data System (ADS)

Asphaug, Erik

2008-09-01

Asteroid 433 Eros is regarded as "fractured monolith" or "shatter pile". But models of fragmentation and disruption (e.g. Benz and Asphaug 1999) predict that any large rocky asteroid should be transformed into a jumble of dust, gravel, talus and boulders, simply because it is much easier to comminute an asteroid than to catastrophically disrupt it. Sometimes the relatively high density of Eros is taken as evidence for a fractured monolithic structure, although the inferred bulk porosity of Eros ( 20-30%) is what one expects for a rubble pile, and is about the porosity of sand and talus. The focus here is that a rubble pile structure is contraindicated by the pronounced network of linear fault-like structures (Buczkowski et al. 2008), some of which radiate from recent large impacts such as Psyche, and which form rectangular boundaries around some of the medium-sized craters. This needs an explanation. Here it is proposed, and quantitatively addressed, that the majority of these faults occur just in the upper tens of meters, where cohesion exceeds gravitational stress even for loose piles of lunar-like regolith. Assuming Eros regolith has the cohesion ( 1 kPa) measured for lunar regolith, then faulting is expected to a depth of 10 m, directly analogous to how faults occur in the upper layers of beach sand. The fact that Eros has few steep slopes anywhere, except for the angles of repose within its craters, at a baseline of 100 m (Zuber et al. 2002), is satisfied by the hypothesis that Eros is a rubble pile rather than a shattered monolith. The low fault stress implied by the above, supports the findings of dense networks of linear structures, ubiquitous features which are otherwise difficult to explain as fractures in a rocky target which has not been disrupted or jumbled against its very low gravity.

An investigation into the effects of excipient particle size, blending techniques and processing parameters on the homogeneity and content uniformity of a blend containing low-dose model drug

PubMed Central

Alyami, Hamad; Dahmash, Eman; Bowen, James

2017-01-01

Powder blend homogeneity is a critical attribute in formulation development of low dose and potent active pharmaceutical ingredients (API) yet a complex process with multiple contributing factors. Excipient characteristics play key role in efficient blending process and final product quality. In this work the effect of excipient type and properties, blending technique and processing time on content uniformity was investigated. Powder characteristics for three commonly used excipients (starch, pregelatinised starch and microcrystalline cellulose) were initially explored using laser diffraction particle size analyser, angle of repose for flowability, followed by thorough evaluations of surface topography employing scanning electron microscopy and interferometry. Blend homogeneity was evaluated based on content uniformity analysis of the model API, ergocalciferol, using a validated analytical technique. Flowability of powders were directly related to particle size and shape, while surface topography results revealed the relationship between surface roughness and ability of excipient with high surface roughness to lodge fine API particles within surface groves resulting in superior uniformity of content. Of the two blending techniques, geometric blending confirmed the ability to produce homogeneous blends at low dilution when processed for longer durations, whereas manual ordered blending failed to achieve compendial requirement for content uniformity despite mixing for 32 minutes. Employing the novel dry powder hybrid mixer device, developed at Aston University laboratory, results revealed the superiority of the device and enabled the production of homogenous blend irrespective of excipient type and particle size. Lower dilutions of the API (1% and 0.5% w/w) were examined using non-sieved excipients and the dry powder hybrid mixing device enabled the development of successful blends within compendial requirements and low relative standard deviation. PMID:28609454

An investigation into the effects of excipient particle size, blending techniques and processing parameters on the homogeneity and content uniformity of a blend containing low-dose model drug.

PubMed

Alyami, Hamad; Dahmash, Eman; Bowen, James; Mohammed, Afzal R

2017-01-01

Powder blend homogeneity is a critical attribute in formulation development of low dose and potent active pharmaceutical ingredients (API) yet a complex process with multiple contributing factors. Excipient characteristics play key role in efficient blending process and final product quality. In this work the effect of excipient type and properties, blending technique and processing time on content uniformity was investigated. Powder characteristics for three commonly used excipients (starch, pregelatinised starch and microcrystalline cellulose) were initially explored using laser diffraction particle size analyser, angle of repose for flowability, followed by thorough evaluations of surface topography employing scanning electron microscopy and interferometry. Blend homogeneity was evaluated based on content uniformity analysis of the model API, ergocalciferol, using a validated analytical technique. Flowability of powders were directly related to particle size and shape, while surface topography results revealed the relationship between surface roughness and ability of excipient with high surface roughness to lodge fine API particles within surface groves resulting in superior uniformity of content. Of the two blending techniques, geometric blending confirmed the ability to produce homogeneous blends at low dilution when processed for longer durations, whereas manual ordered blending failed to achieve compendial requirement for content uniformity despite mixing for 32 minutes. Employing the novel dry powder hybrid mixer device, developed at Aston University laboratory, results revealed the superiority of the device and enabled the production of homogenous blend irrespective of excipient type and particle size. Lower dilutions of the API (1% and 0.5% w/w) were examined using non-sieved excipients and the dry powder hybrid mixing device enabled the development of successful blends within compendial requirements and low relative standard deviation.

Development of a solidified self-microemulsifying drug delivery system (S-SMEDDS) for atorvastatin calcium with improved dissolution and bioavailability.

PubMed

Yeom, Dong Woo; Son, Ho Yong; Kim, Jin Han; Kim, Sung Rae; Lee, Sang Gon; Song, She Hyon; Chae, Bo Ram; Choi, Young Wook

2016-06-15

To improve the dissolution and oral bioavailability (BA) of atorvastatin calcium (ATV), we previously introduced an optimized self-microemulsifying drug delivery system (SMEDDS) using Capmul(®) MCM (oil), Tween(®) 20 (surfactant), and tetraglycol (cosurfactant). In this study, various solid carriers were employed to develop a solidified SMEDDS (S-SMEDDS): mannitol (M) and lactose (L) as water-soluble carriers, and Sylysia(®) 350 (S) and Aerosil(®) 200 (A) as water-insoluble carriers. Maximum solidifying capacities (SCmax) of water-insoluble carriers were significantly greater than those of water-soluble carriers were. The resultant powders were free flowing with an angle of repose <40° and Carr's index 5-20%, regardless of the solid carrier types. S-SMEDDS with mannitol (S(M)-SMEDDS) or lactose (S(L)-SMEDDS) had a smaller droplet size and greater dissolution than S-SMEDDS with Sylysia(®) 350 (S(S)-SMEDDS) or Aerosil(®) 200 (S(A)-SMEDDS). Following oral administration of various formulations to rats at a dose equivalent to 25mg/kg of ATV, plasma drug levels were measured by LC-MS/MS. The relative BAs (RBAs) of SMEDDS, S(M)-SMEDDS, and S(S)-SMEDDS were 345%, 216%, and 160%, respectively, compared to that of ATV suspension. Additionally, at a reduced dose of ATV equivalent to 5mg/kg, the RBAs of S(M)-SMEDDS and S(S)-SMEDDS compared to that of SMEDDS were 101% and 65%, respectively. These results suggest that S(M)-SEMDDS offers great potential for the development of solid dosage forms with improved oral absorption of drugs with poor water solubility. Copyright © 2016 Elsevier B.V. All rights reserved.

Diffusive smoothing of surfzone bathymetry by gravity-driven sediment transport

NASA Astrophysics Data System (ADS)

Moulton, M. R.; Elgar, S.; Raubenheimer, B.

2012-12-01

Gravity-driven sediment transport often is assumed to have a small effect on the evolution of nearshore morphology. Here, it is shown that down-slope gravity-driven sediment transport is an important process acting to smooth steep bathymetric features in the surfzone. Gravity-driven transport can be modeled as a diffusive term in the sediment continuity equation governing temporal (t) changes in bed level (h): ∂h/∂t ≈ κ ▽2h, where κ is a sediment diffusion coefficient that is a function of the bed shear stress (τb) and sediment properties, such as the grain size and the angle of repose. Field observations of waves, currents, and the evolution of large excavated holes (initially 10-m wide and 2-m deep, with sides as steep as 35°) in an energetic surfzone are consistent with diffusive smoothing by gravity. Specifically, comparisons of κ estimated from the measured bed evolution with those estimated with numerical model results for several transport theories suggest that gravity-driven sediment transport dominates the bed evolution, with κ proportional to a power of τb. The models are initiated with observed bathymetry and forced with observed waves and currents. The diffusion coefficients from the measurements and from the model simulations were on average of order 10-5 m2/s, implying evolution time scales of days for features with length scales of 10 m. The dependence of κ on τb varies for different transport theories and for high and low shear stress regimes. The US Army Corps of Engineers Field Research Facility, Duck, NC provided excellent logistical support. Funded by a National Security Science and Engineering Faculty Fellowship, a National Defense Science and Engineering Graduate Fellowship, and the Office of Naval Research.

Topography and geomorphology of the Huygens landing site on Titan

USGS Publications Warehouse

Soderblom, L.A.; Tomasko, M.G.; Archinal, B.A.; Becker, T.L.; Bushroe, M.W.; Cook, D.A.; Doose, L.R.; Galuszka, D.M.; Hare, T.M.; Howington-Kraus, E.; Karkoschka, E.; Kirk, R.L.; Lunine, J.I.; McFarlane, E.A.; Redding, B.L.; Rizk, B.; Rosiek, M.R.; See, C.; Smith, P.H.

2007-01-01

The Descent Imager/Spectral Radiometer (DISR) aboard the Huygens Probe took several hundred visible-light images with its three cameras on approach to the surface of Titan. Several sets of stereo image pairs were collected during the descent. The digital terrain models constructed from those images show rugged topography, in places approaching the angle of repose, adjacent to flatter darker plains. Brighter regions north of the landing site display two styles of drainage patterns: (1) bright highlands with rough topography and deeply incised branching dendritic drainage networks (up to fourth order) with dark-floored valleys that are suggestive of erosion by methane rainfall and (2) short, stubby low-order drainages that follow linear fault patterns forming canyon-like features suggestive of methane spring-sapping. The topographic data show that the bright highland terrains are extremely rugged; slopes of order of 30?? appear common. These systems drain into adjacent relatively flat, dark lowland terrains. A stereo model for part of the dark plains region to the east of the landing site suggests surface scour across this plain flowing from west to east leaving ???100-m-high bright ridges. Tectonic patterns are evident in (1) controlling the rectilinear, low-order, stubby drainages and (2) the "coastline" at the highland-lowland boundary with numerous straight and angular margins. In addition to flow from the highlands drainages, the lowland area shows evidence for more prolific flow parallel to the highland-lowland boundary leaving bright outliers resembling terrestrial sandbars. This implies major west to east floods across the plains where the probe landed with flow parallel to the highland-lowland boundary; the primary source of these flows is evidently not the dendritic channels in the bright highlands to the north. ?? 2007 Elsevier Ltd. All rights reserved.

Nanoparticle formulation by Büchi B-90 Nano Spray Dryer for oral mucoadhesion

PubMed Central

Harsha, Sree N; Aldhubiab, Bander E; Nair, Anroop B; Alhaider, Ibrahim Abdulrahman; Attimarad, Mahesh; Venugopala, Katharigatta N; Srinivasan, Saminathan; Gangadhar, Nagesh; Asif, Afzal Haq

2015-01-01

Diabetes is considered one of the main threats to global public health in this era. It is increasing rapidly in every part of the world; the prevalence of the disease will grow to the point where 366 million people will be affected by 2030. The prevalence of diabetes mellitus (DM) in the Saudi population is high, and the majority of patients suffer from type 2 DM. Marketed oral antidiabetic drugs have indicated poor tolerability during chronic treatments, and this contributes to the moderately large proportion of type 2 DM patients that remain inadequately managed. Vildagliptin nanospheres were prepared with aminated gelatin using a spray-drying method; narrow particle-size distribution was seen at 445 nm. The angle of repose was found to be θ <33.5°. The nanospheres appeared to be spherical with a smooth surface. The drug content and percentage yield of the nanospheres were found to be 76.2%±4.6% and 83%±2%, respectively. The nanosphere-swell profile was found to be 165%±7%. The pure drug was 100% dissolved in 30 minutes, and the nanosphere formulation took 12 hours to dissolve (97.5%±2%), and followed a Korsmeyer–Peppas kinetic model with an R2 of 0.9838. The wash-off test of nanospheres found that they exhibited an excellent mucoadhesive property at 86.7% for 8 hours. The stability-study data showed no changes in the physicochemical properties of the nanospheres, and suggested that the nanospheres be stored below room temperature. The amount of vildagliptin retained was 1.6% within 3 hours, and in comparison with the gelatin vildagliptin nanoparticles formulation, the percentage that was retained was much higher (98.2% in 12 hours). PMID:25670882

Improvement of flow and bulk density of pharmaceutical powders using surface modification.

PubMed

Jallo, Laila J; Ghoroi, Chinmay; Gurumurthy, Lakxmi; Patel, Utsav; Davé, Rajesh N

2012-02-28

Improvement in flow and bulk density, the two most important properties that determine the ease with which pharmaceutical powders can be handled, stored and processed, is done through surface modification. A limited design of experiment was conducted to establish a standardized dry coating procedure that limits the extent of powder attrition, while providing the most consistent improvement in angle of repose (AOR). The magnetically assisted impaction coating (MAIC) was considered as a model dry-coater for pharmaceutical powders; ibuprofen, acetaminophen, and ascorbic acid. Dry coated drug powders were characterized by AOR, particle size as a function of dispersion pressure, particle size distribution, conditioned bulk density (CBD), Carr index (CI), flow function coefficient (FFC), cohesion coefficient using different instruments, including a shear cell in the Freeman FT4 powder rheometer, and Hansen flowability index. Substantial improvement was observed in all the measured properties after dry coating relative to the uncoated powders, such that each powder moved from a poorer to a better flow classification and showed improved dispersion. The material intrinsic property such as cohesion, plotted as a function of particle size, gave a trend similar to those of bulk flow properties, AOR and CI. Property improvement is also illustrated in a phase map of inverse cohesion (or FFC) as a function of bulk density, which also indicated a significant positive shift due to dry coating. It is hoped that such phase maps are useful in manufacturing decisions regarding the need for dry coating, which will allow moving from wet granulation to roller compaction or to direct compression based formulations. Copyright © 2011 Elsevier B.V. All rights reserved.

Enhanced stability of steep channel beds to mass failure and debris flow initiation

NASA Astrophysics Data System (ADS)

Prancevic, J.; Lamb, M. P.; Ayoub, F.; Venditti, J. G.

2015-12-01

Debris flows dominate bedrock erosion and sediment transport in very steep mountain channels, and are often initiated from failure of channel-bed alluvium during storms. While several theoretical models exist to predict mass failures, few have been tested because observations of in-channel bed failures are extremely limited. To fill this gap in our understanding, we performed laboratory flume experiments to identify the conditions necessary to initiate bed failures in non-cohesive sediment of different sizes (D = 0.7 mm to 15 mm) on steep channel-bed slopes (S = 0.45 to 0.93) and in the presence of water flow. In beds composed of sand, failures occurred under sub-saturated conditions on steep bed slopes (S > 0.5) and under super-saturated conditions at lower slopes. In beds of gravel, however, failures occurred only under super-saturated conditions at all tested slopes, even those approaching the dry angle of repose. Consistent with theoretical models, mass failures under super-saturated conditions initiated along a failure plane approximately one grain-diameter below the bed surface, whereas the failure plane was located near the base of the bed under sub-saturated conditions. However, all experimental beds were more stable than predicted by 1-D infinite-slope stability models. In partially saturated sand, enhanced stability appears to result from suction stress. Enhanced stability in gravel may result from turbulent energy losses in pores or increased granular friction for failures that are shallow with respect to grain size. These grain-size dependent effects are not currently included in stability models for non-cohesive sediment, and they may help to explain better the timing and location of debris flow occurrence.

Sedimentary processes of the Bagnold Dunes: Implications for the eolian rock record of Mars.

PubMed

Ewing, R C; Lapotre, M G A; Lewis, K W; Day, M; Stein, N; Rubin, D M; Sullivan, R; Banham, S; Lamb, M P; Bridges, N T; Gupta, S; Fischer, W W

2017-12-01

The Mars Science Laboratory rover Curiosity visited two active wind-blown sand dunes within Gale crater, Mars, which provided the first ground-based opportunity to compare Martian and terrestrial eolian dune sedimentary processes and study a modern analog for the Martian eolian rock record. Orbital and rover images of these dunes reveal terrestrial-like and uniquely Martian processes. The presence of grainfall, grainflow, and impact ripples resembled terrestrial dunes. Impact ripples were present on all dune slopes and had a size and shape similar to their terrestrial counterpart. Grainfall and grainflow occurred on dune and large-ripple lee slopes. Lee slopes were ~29° where grainflows were present and ~33° where grainfall was present. These slopes are interpreted as the dynamic and static angles of repose, respectively. Grain size measured on an undisturbed impact ripple ranges between 50 μm and 350 μm with an intermediate axis mean size of 113 μm (median: 103 μm). Dissimilar to dune eolian processes on Earth, large, meter-scale ripples were present on all dune slopes. Large ripples had nearly symmetric to strongly asymmetric topographic profiles and heights ranging between 12 cm and 28 cm. The composite observations of the modern sedimentary processes highlight that the Martian eolian rock record is likely different from its terrestrial counterpart because of the large ripples, which are expected to engender a unique scale of cross stratification. More broadly, however, in the Bagnold Dune Field as on Earth, dune-field pattern dynamics and basin-scale boundary conditions will dictate the style and distribution of sedimentary processes.

Sedimentary processes of the Bagnold Dunes: Implications for the eolian rock record of Mars

PubMed Central

Lapotre, M. G. A.; Lewis, K. W.; Day, M.; Stein, N.; Rubin, D. M.; Sullivan, R.; Banham, S.; Lamb, M. P.; Bridges, N. T.; Gupta, S.; Fischer, W. W.

2017-01-01

Abstract The Mars Science Laboratory rover Curiosity visited two active wind‐blown sand dunes within Gale crater, Mars, which provided the first ground‐based opportunity to compare Martian and terrestrial eolian dune sedimentary processes and study a modern analog for the Martian eolian rock record. Orbital and rover images of these dunes reveal terrestrial‐like and uniquely Martian processes. The presence of grainfall, grainflow, and impact ripples resembled terrestrial dunes. Impact ripples were present on all dune slopes and had a size and shape similar to their terrestrial counterpart. Grainfall and grainflow occurred on dune and large‐ripple lee slopes. Lee slopes were ~29° where grainflows were present and ~33° where grainfall was present. These slopes are interpreted as the dynamic and static angles of repose, respectively. Grain size measured on an undisturbed impact ripple ranges between 50 μm and 350 μm with an intermediate axis mean size of 113 μm (median: 103 μm). Dissimilar to dune eolian processes on Earth, large, meter‐scale ripples were present on all dune slopes. Large ripples had nearly symmetric to strongly asymmetric topographic profiles and heights ranging between 12 cm and 28 cm. The composite observations of the modern sedimentary processes highlight that the Martian eolian rock record is likely different from its terrestrial counterpart because of the large ripples, which are expected to engender a unique scale of cross stratification. More broadly, however, in the Bagnold Dune Field as on Earth, dune‐field pattern dynamics and basin‐scale boundary conditions will dictate the style and distribution of sedimentary processes. PMID:29497590

Design and evaluation of mucoadhesive vaginal tablets of tenofovir disoproxil fumarate for pre-exposure prophylaxis of HIV.

PubMed

Khan, Arshad Bashir; Thakur, Ram Sharnagat

2018-03-01

To design and evaluate novel, feasible, safe, mucoadhesive intravaginal tablets of tenofovir disoproxil fumarate (TDF). It may provide pre-exposure prophylaxis for women against HIV. TDF intravaginal tablets were formulated employing poylvinylpyrrolidone (PVP) as the matrix forming polymer and various mucoadhesive polymers such as carbopol 934, 940, chitosan, and sodium carboxymethylcellulose (SCMC). Wet granulation was used. The evaluation involved testing drug-excipient compatibility, precompression parameters such as percentage yield, bulk density and tapped density of the granules, Carr's index, Hausner ratio, angle of repose, post compression parameters such as color, shape, physical dimensions, weight variation, hardness, friability, swelling index, assay, in vitro dissolution study and ex vivo mucoadhesion studies. Based on in vitro evaluation, C1 was selected as the best formulation and evaluated further for release kinetics, curve fitting analysis, absorption studies using liquid chromatography-mass spectrometry (LC-MS) technique and histopathological assessment in female Sprague-Dawley rats. C1 followed Higuchi model kinetics. Accelerated stability study was as per ICH guidelines by keeping C1 at 40 ± 2 °C and 75 ± 5% RH for six months. C1 was selected as the best formulation due to better swelling index (65.93% at 24 h), prolonged release of 100.62% cumulative drug release (CDR) at 24 h, superior mucoadhesion force (35.93 × 10 2 dynes/cm 2 ) and retention time (16 h). The study revealed that C1 remained stable for six months. C1 showed nil systemic absorption which is desirable and according to histopathological study, C1, exhibited minimal damage on the rat vaginal epithelium indicating safety.

The Puu Oo eruption of Kilauea Volcano, Hawaii

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

Wolfe, E.W.

1988-01-01

The Puu Oo eruption is the most voluminous and longest-lived historical flank eruption of Kilauea volcano. A pattern of episodic lava discharge developed in which relatively brief periods of vigorous fountaining and high-volume flow production alternated with longer repose periods. The activity was intensely monitored, and results of the first 11/2 yrs of observation and measurement are reported, including geologic observations, lava sampling, temperature measurements, compositional analyses, petrologic study, studies of gas composition and the role of gases in the eruptive process, geodetic measurements during emplacement of the feeder dike, and seismic and electrical studies.

DRDC Toronto Technical Stream Integrated Capabilities and Vision

DTIC Science & Technology

2011-09-01

du RT, et les présenter à la séance d’information 2010 destinée à tout le personnel, puis à la réunion du Comité de gestion . Reposant sur une...profession technique, c) adoption d’une culture de collaboration et de réseautage, d ) élargissement de l’influence de la profession technique. Grâce à...d’information 2010 destinée à tout le personnel, puis à la réunion du Comité de gestion . Résultats : Une équipe de projet, composée de huit membres du

Paragangliome malin orbitaire, à propos d’un cas

PubMed Central

Andaloussi, Idriss Benatiya; Maaroufi, Mustapha; Benzagmout, Mohammed; Harmouch, Taoufiq; Abdellaoui, Meryem; Bhallil, Salima; Tizniti, Siham; Elfaiz, Mohammed Chaoui; Amarti, Afaf; Tahri, Hicham

2012-01-01

Les paragangliomes sont des tumeurs neuroendocrines développées aux dépens du système nerveux parasympathique. Ils peuvent se localiser n’ importe où dans l’organisme depuis la tète et cou jusqu’au pelvis. La localisation orbitaire de cette tumeur est très rare. Nous présentons le cas d’un patient âgé de 37 ans qui présente depuis 4 mois une exophtalmie unilatérale droite, d’installation progressive, sans douleur ni baisse de l’acuité visuelle associés. L’examen général montre une tuméfaction sous le cuire chevelu, sans adénopathies locorégionales ni hépato ou splénomégalie. La tomodensitométrie retrouve un processus tumoral occupant le cadran supéro-externe de l’orbite droite, mesurant 38 mm de grand axe, envahissant la paroi supérieure et externe de l’orbite avec une importante ostéolyse. Un body scan révèle alors une métastase pulmonaire. L’examen histopathologique complétés par l’immunohistochimie, réalisé après biopsie, révèle un marquage cytoplasmique par l’anticorps anti-chromogranin, l’anticorps anti-synaptophysine et un marquage des vaisseaux par l’anticorps anti-CD31 soulignant l’architecture en zellbalen des nids tumoraux. Cet aspect est en faveur d’un paragangliome malin. Une exérèse chirurgicale incomplète suivie d’une radiothérapie adjuvante, sont alors réalisés. L’origine exacte de cette tumeur au sein de l’orbite reste très controversée. L’exophtalmie reste le principal signe révélateur. La tomodensitométrie, l’imagerie par résonnance magnétique et la scintigraphie au Metaiodobenzylguanidine radioinonisée à l’iode (MIBG-I131) permettent d’orienter le diagnostic et faire un bilan d’extension de la tumeur. Le diagnostic de certitude repose sur l’histopathologie et l’immunohistochimie. L’excision totale de la lésion est le traitement de choix pour les lésions bien délimitées. Dans les formes plus étendues le traitement repose sur l’excision incomplète associée à une radiothérapie adjuvante ou au MIBG I 131. La localisation orbitaire du paragangliome reste très rare. Son diagnostic est difficile et repose essentiellement sur l’immunohistochimie. Son pronostic dépend essentiellement de l’extension locale et de la présence de métastases à distance qui signe le caractère malin du paragangliome. PMID:22891095

Developpement de techniques de diagnostic non intrusif par tomographie optique

NASA Astrophysics Data System (ADS)

Dubot, Fabien

Que ce soit dans les domaines des procedes industriels ou de l'imagerie medicale, on a assiste ces deux dernieres decennies a un developpement croissant des techniques optiques de diagnostic. L'engouement pour ces methodes repose principalement sur le fait qu'elles sont totalement non invasives, qu'elle utilisent des sources de rayonnement non nocives pour l'homme et l'environnement et qu'elles sont relativement peu couteuses et faciles a mettre en oeuvre comparees aux autres techniques d'imagerie. Une de ces techniques est la Tomographie Optique Diffuse (TOD). Cette methode d'imagerie tridimensionnelle consiste a caracteriser les proprietes radiatives d'un Milieu Semi-Transparent (MST) a partir de mesures optiques dans le proche infrarouge obtenues a l'aide d'un ensemble de sources et detecteurs situes sur la frontiere du domaine sonde. Elle repose notamment sur un modele direct de propagation de la lumiere dans le MST, fournissant les predictions, et un algorithme de minimisation d'une fonction de cout integrant les predictions et les mesures, permettant la reconstruction des parametres d'interet. Dans ce travail, le modele direct est l'approximation diffuse de l'equation de transfert radiatif dans le regime frequentiel tandis que les parametres d'interet sont les distributions spatiales des coefficients d'absorption et de diffusion reduit. Cette these est consacree au developpement d'une methode inverse robuste pour la resolution du probleme de TOD dans le domaine frequentiel. Pour repondre a cet objectif, ce travail est structure en trois parties qui constituent les principaux axes de la these. Premierement, une comparaison des algorithmes de Gauss-Newton amorti et de Broyden- Fletcher-Goldfarb-Shanno (BFGS) est proposee dans le cas bidimensionnel. Deux methodes de regularisation sont combinees pour chacun des deux algorithmes, a savoir la reduction de la dimension de l'espace de controle basee sur le maillage et la regularisation par penalisation de Tikhonov pour l'algorithme de Gauss-Newton amorti, et les regularisations basees sur le maillage et l'utilisation des gradients de Sobolev, uniformes ou spatialement dependants, lors de l'extraction du gradient de la fonction cout, pour la methode BFGS. Les resultats numeriques indiquent que l'algorithme de BFGS surpasse celui de Gauss-Newton amorti en ce qui concerne la qualite des reconstructions obtenues, le temps de calcul ou encore la facilite de selection du parametre de regularisation. Deuxiemement, une etude sur la quasi-independance du parametre de penalisation de Tikhonov optimal par rapport a la dimension de l'espace de controle dans les problemes inverses d'estimation de fonctions spatialement dependantes est menee. Cette etude fait suite a une observation realisee lors de la premiere partie de ce travail ou le parametre de Tikhonov, determine par la methode " L-curve ", se trouve etre independant de la dimension de l'espace de controle dans le cas sous-determine. Cette hypothese est demontree theoriquement puis verifiee numeriquement sur un probleme inverse lineaire de conduction de la chaleur puis sur le probleme inverse non-lineaire de TOD. La verification numerique repose sur la determination d'un parametre de Tikhonov optimal, defini comme etant celui qui minimise les ecarts entre les cibles et les reconstructions. La demonstration theorique repose sur le principe de Morozov (discrepancy principle) dans le cas lineaire, tandis qu'elle repose essentiellement sur l'hypothese que les fonctions radiatives a reconstruire sont des variables aleatoires suivant une loi normale dans le cas non-lineaire. En conclusion, la these demontre que le parametre de Tikhonov peut etre determine en utilisant une parametrisation des variables de controle associee a un maillage lâche afin de reduire les temps de calcul. Troisiemement, une methode inverse multi-echelle basee sur les ondelettes associee a l'algorithme de BFGS est developpee. Cette methode, qui s'appuie sur une reformulation du probleme inverse original en une suite de sous-problemes inverses de la plus grande echelle a la plus petite, a l'aide de la transformee en ondelettes, permet de faire face a la propriete de convergence locale de l'optimiseur et a la presence de nombreux minima locaux dans la fonction cout. Les resultats numeriques montrent que la methode proposee est plus stable vis-a-vis de l'estimation initiale des proprietes radiatives et fournit des reconstructions finales plus precises que l'algorithme de BFGS ordinaire tout en necessitant des temps de calcul semblables. Les resultats de ces travaux sont presentes dans cette these sous forme de quatre articles. Le premier article a ete accepte dans l'International Journal of Thermal Sciences, le deuxieme est accepte dans la revue Inverse Problems in Science and Engineering, le troisieme est accepte dans le Journal of Computational and Applied Mathematics et le quatrieme a ete soumis au Journal of Quantitative Spectroscopy & Radiative Transfer. Dix autres articles ont ete publies dans des comptes-rendus de conferences avec comite de lecture. Ces articles sont disponibles en format pdf sur le site de la Chaire de recherche t3e (www.t3e.info).

Hypnosis in the Management of Sleep Disorders.

PubMed

Becker, Philip M

2015-03-01

Hypnosis has been used to manage insomnia and disorders of arousal. The alteration in the state of consciousness produced during hypnotic trance is more similar to relaxed reverie than sleep. Hypnosis typically occurs in a state of repose and the accomplished subject may have no recollection of the experience during a trance, 2 commonalities with sleep. Because hypnosis allows for relaxation, increased suggestibility, posthypnotic suggestion, imagery rehearsal, access to preconscious cognitions and emotions, and cognitive restructuring, disorders of sleep such as the insomnias, parasomnias, and related mood or anxiety disorders can be amenable to this therapeutic intervention. Copyright © 2015 Elsevier Inc. All rights reserved.

Mesure de coefficients d'absorption de plasmas créés par laser nanoseconde

NASA Astrophysics Data System (ADS)

Thais, F.; Chenais-Popovics, C.; Eidmann, K.; Bastiani, S.; Blenski, T.; Gilleron, F.

2005-06-01

La mesure des coefficients d'absorption dans les plasmas chauds est particulièrement utile dans le domaine de la fusion par confinement inertiel ainsi que dans divers contextes en astrophysique. Le développement des calculs de physique atomique qui y sont associés repose sur des hypothèses qu'il est nécessaire de vérifier dans la plus large gamme possible de conditions physiques. Nous présentons ici la méthode de mesure et d'analyse employée en nous appuyant sur l'exemple des cibles multicouches nickel/aluminium.

Sustained drug release and electrochemical performance of ethyl cellulose-magnesium hydrogen phosphate composite.

PubMed

Mohammad, Faruq; Arfin, Tanvir; Al-Lohedan, Hamad A

2017-02-01

In this, a sol-gel method was applied to prepare ethyl cellulose-magnesium hydrogen phosphate (EC-MgHPO 4 ) composite that can have potential applications in the sensory, pharmaceutical, and biomedical sectors. The formed composite was thoroughly characterized by making use of the instrumental analysis such as UV-Vis, FT-IR, HRTEM, EDAX, SEM and XRD. For the composite, the other parameters determined includes the water uptake, porosity, thickness, bulk and tapped densities, angle of repose, Carr's index and Hausner ratio. From the results, the material found to exhibit good flowing properties with a Carr's index of 11.11%, Hausner ratio of 1.125, and angle of response of 33°. The EDAX spectrum and HRTEM analysis confirmed for the composite formation and the particles size is investigated to be around 52nm. The surface porosity due to the EC matrices was confirmed by the SEM analysis, which further used for the loading of drug, Proguanil. In addition, the material's conductivity was studied by taking uni-univalent electrolyte solution (KCl and NaCl) indicated that the conductivity follows the order of KCl>NaCl, while the activation energy obtained from Arrhenius method resembled that the conductivity is strongly influenced by the electrolyte type used. We found from the analysis that, with a decrease in the size of hydrated radii of ions, the conductivity of EC-MgHPO 4 material also observed to be decreased in the order K + >Na + and the material proved to be mechanically stable and can be operated over a range of pHs, temperatures, and electrolyte solutions. Further, the drug loading and efficiency studies indicated that the material can trap up to 80% of Proguanil (antimalarial drug) applied for its loading. The Proguanil drug release profiles confirmed for the controlled and sustained release from the EC-MgHPO 4 matrix, as the material can release up to 87% of its total loaded drug over a 90min period. Finally, the cell viability and proliferation studies tested against two different cell cultures of BRL-3A rat liver and H9c2 cardiomyoblasts indicated the non-toxic nature and safer applicability of the EC-MgHPO 4 (25-500μg/mL, 24h). Overall, the results of the study confirm for the safer applicability of the composite towards biosensor, drug delivery, scaffolding, and bioanalytical (quality control) applications. Copyright © 2016 Elsevier B.V. All rights reserved.

Cryptographie quantique à variables continues

NASA Astrophysics Data System (ADS)

Bencheikh, K.; Jankovic, A.; Symul, T.; Levenson, J. A.

2002-06-01

Nous avons élaboré un protocole de cryptographie quantique qui permet de générer et de distribuer une clé secrète aléatoire. Le protocole repose sur l'utilisation de paires de champs électromagnétiques dont les quadratures présentent des corrélations quantiques de type Einstein-Podolsky-Rosen. Les fluctuations quantiques instantanése constituent les bits aléatoires de la clé secrète, et la dégradation irréversible des corrélations quantiques des quadratures causée par une tierce personne permet de la détecter et de garantir la sécurité d'échange.

Vocanic Deformations During Repose Interval Revealed by GPS Measurements, Batur Volcano, Indonesia

NASA Astrophysics Data System (ADS)

Nishimae, K.; Fujii, N.; Kimata, F.; Murase, M.; Suganda, O. K.; Abidin, H. Z.

2005-12-01

Batur volcano is located north west of Bali Island in Indonesia.This volcano has two calderas with more than 10 km in diameter. Recent eruptions with lava flow occurred in 1963 and 1974. No effusion of lava has been observed since 1990, although steam explosions occurred August 1994, November 1997 and June 1998.This suggests that magmatic activity of this volcano would keep its high level since 1994.GPS observation network of this volcano has been kept by Institute Technology of Bandung (ITB) and Volcano Survey of Indonesia (VSI).The network was consisted of 10 observation points at the beginning in 1999, and now it becomes 23 observation points. We have made GPS campaign observations about five times from 2003 to 2005. Each campaign observation consisted of a couple of days of measurements for each observation point. In order to keep the quality of data as high as possible, observations have been made at least 12 hours of continuous data for each point. In this report, results of two campaign observations (December 2004 and July 2005) are used for the analysis. The data thus obtained are fitted to the Mogi source (i.e. a point source model) to locate the depth and amount of volume changes for 7 months. Location of the Mogi source was obtained about 4km southeast of the summit of central cone, and 3km depth with deflation volume change of 1.3_~106 m3 for about 7months. For the period from 1999 to 2004, estimated volume change suggests a continuous deflation throughout this period, although the reliability of data was not so high. Continuous deflations might be likely after the last effusive eruption in 1974, would suggest that shallow part of magma beneath the central cone would probably be drained down to further deep, or shrinkage of magma associated with the cooling or solidification. Further data are obviously needed to discriminate the mechanisms of the deformation process during the repose period in this volcano.

Evaluation of Gum of Moringa oleifera as a Binder and Release Retardant in Tablet Formulation

PubMed Central

Panda, D. S.; Choudhury, N. S. K.; Yedukondalu, M.; Si, S.; Gupta, R.

2008-01-01

The present study was undertaken to find out the potential of gum from Moringa oleifera to act as a binder and release retardant in tablet formulations. The effect of calcium sulphate dihydrate (water insoluble) and lactose (water soluble) diluent on the release of propranolol hydrochloride was studied. The DSC thermograms of drug, gum and mixture of gum/drug indicated no chemical interaction. Tablets (F1, F2, F3, and F4) were prepared containing calcium sulphate dihydrate as diluent, propranolol hydrochloride as model drug using 10%, 8%, 6% and 4% w/v of gum solution as binder. Magnesium stearate was used as lubricant. Physical and technological properties of granules and tablets like flow rate, Carr index, Hausner ratio, angle of repose, hardness, friability and disintegration time were determined and found to be satisfactory. Tablets were prepared by wet granulation method containing calcium sulphate dihydrate as excipient, propranolol hydrochloride as model drug using 10%, 20% and 30% of gum as release retardant, magnesium stearate was used as lubricant. Similarly tablets were prepared replacing lactose with calcium sulphate dihydrate. Despite of the widely varying physico-chemical characteristics of the excipients, the drug release profiles were found to be similar. The drug release increased with increasing proportions of the excipient and decreased proportion of the gum irrespective of the solubility characteristics of the excipient. The values of release exponent ‘n’ are between 0.37 and 0.54. This implies that the release mechanism is Fickian. There is no evidence that the dissolution or erosion of the excipient has got any effect on the release of the drug. The t50% values for tablets containing calcium sulphate dihydrate were on an average 10%-15% longer than the tablets containing lactose as excipient. These relatively small differences in t50% values suggest that the nature of excipient used appeared to play a minor role in regulating the release, while the gum content was a major factor. PMID:21394258

Modification of crystal habit of ibuprofen using the phase partition technique: effect of aerosil and tween 80 in binding solvent.

PubMed

Umprayn, K; Luengtummuen, A; Kitiyadisai, C; Pornpiputsakul, T

2001-11-01

A ternary diagram, representing the solubility of binding solvent (chloroform) in a mixture of ethanol and water, was constructed. For this study, the solvent mixture that gave the best ibuprofen pellets (IPs) was composed of chloroform.ethanol:water at a ratio of 1.5%:8%:90.5%. The suitable agitator speed, temperature, and mixing time were found to be 1,500 rpm, 25 degrees C +/- 2 degrees C, and 20 min, respectively. In addition, suitable stirring time when the phase partition process of IPs began was 15 min. IPs obtained from these conditions were small and round, approximately 1 mm; surface determination by scanning electron microscopy (SEM) indicated that the IPs were composed of drug microcrystals rearranged on the surface. For the dissolution, IPs showed lower drug release when compared with pure ibuprofen crystal (IC) (f2 analysis). An attempt to modify the dissolution property of IP by incorporating various concentrations of Aerosil and Tween 80 in the binding solvent was made. Microscopic appearance showed that both Aerosil and Tween 80 gave less spherical pellets when compared with the use of binding solvent alone. For both the Aerosil and Tween 80 employed, the results indicated a change in rearrangement of drug microcrystals and a change in crystal habit. However, Tween 80 gave more change of the crystallographic direction of drug microcrystals than Aerosil. In term of dissolution, the results showed that employing Tween 80 at 1.2% gave the highest drug release compared to the use of Aerosil and IC alone (f2 analysis). These pellets had a good flow property, as indicated by Carr's compressibility, flow rate, and angle of repose, and they can be compressed into a tablet, encapsulated by suitable polymer, or pulverized to obtain micronized crystals. In the case of compression into tablets, the dissolution profiles of these tablets compared with those of commercial product meet the USP 24 requirement (Q > or = 80% at 60 min).

On the Hydrogranular Dynamics of Magmatic Gravity Currents

NASA Astrophysics Data System (ADS)

McIntire, M. Z.; Bergantz, G. W.; Schleicher, J.; Burgisser, A.

2016-12-01

Magmatic processes are generally governed by multi-phase interactions of silicate liquid, crystals, and bubbles. However, the modes of dissipation and the manner that stress is transmitted are poorly understood. We use a model of a simple but widely applicable gravity current as a means to exemplify the hydrogranular dynamics in crystal-rich magmas. Viscous and lubrication forces are of special interest because they have a dual role in dispersal and mixing in a crystal-rich gravity current. For example, lubrication forces provide an initial apparent yield strength by inducing a negative pore pressure as crystals move apart. However, once the gravity current is underway, lubrication forces reduce the dissipation due to collision and frictional contact.The gravity current is initiated by a combination of toppling and sliding along a well-defined granular fault. This produces three distinct regimes: a quasi-static base, an overlying particle hump that translates in a quasi-plastic fashion by grain-passing and rolling until the angle of repose is reached, and a viscous particle current. The current initially forms a leading vortex at the head, but the loss of crystals by sedimentation-assisted granular capture by an upward growing particle front drains energy from the flow. The vortex is soon abandoned, but persists in the reservoir as a fossil feature of orphaned crystals in a smear of previous intercumulate fluid. The kinetic energy of the most active crystals decays in a dual fashion, initially linearly, then parabolically with a near symmetrical increase and loss of kinetic energy.There is very little entrainment and mixing between intercumulate and reservoir fluids from magmatic gravity currents. Only a thin seam of reservoir melt is captured by the base of the flow as it descends across the floor. Hence magmatic gravity currents, while producing modest amounts of crystal sorting, are not effective agents of mixing as lubrication and viscous forces inhibit interpenetration of reservoir fluid.

Investigation of Reversing Sand Dunes at the Bruneau Dunes, Idaho, as Analogs for Features on Mars

NASA Astrophysics Data System (ADS)

Zimbelman, J. R.; Scheidt, S. P.

2012-12-01

The Bruneau Dunes in south-central Idaho include several large reversing sand dunes located within a cut-off meander of the Snake River. These dunes include the largest single-structured sand dune present in North America. Wind records from the Remote Automated Weather Station (RAWS) installation at the Mountain Home Air Force Base, which is ~21 km NW of the Bruneau Dunes, have proved to be very helpful in assessing the regional wind patterns at this section of the western Snake River Plains province; a bimodal wind regime is present, with seasonal changes of strong (sand-moving) winds blowing from either the northwest or the southeast. During April of 2011, we obtained ten precision topographic surveys across the southernmost reversing dune using a Differential Global Positioning System (DGPS). The DGPS data document the shape of the dune going from a low, broad sand ridge at the southern distal end of the dune to the symmetrically shaped 112-m-high central portion of the dune, where both flanks of the dune consist of active slopes near the angle of repose. These data will be useful in evaluating the reversing dune hypothesis proposed for enigmatic features on Mars called Transverse Aeolian Ridges (TARs), which could have formed either as large mega-ripples or small sand dunes. The symmetric profiles across TARs with heights greater than 1 m are more consistent with measured profiles of reversing sand dunes than with measured profiles of mega-ripples (whose surfaces are coated by large particles ranging from coarse sand to gravel, moved by saltation-induced creep). Using DGPS to monitor changes in the three-dimensional location of the crests of the reversing dunes at the Bruneau Dunes should provide a means for estimating the likely timescale for changes of TAR crests if the Martian features are indeed formed in the same manner as reversing sand dunes on Earth.

IDENTIFICATION OF PHARMACEUTICAL EXCIPIENT BEHAVIOR OF CHICKPEA (CICER ARIETINUM) STARCH IN GLICLAZIDE IMMEDIATE RELEASE TABLETS.

PubMed

Meka, Venkata Srikanth; Yee, Phung; Sheshala, Ravi

2016-01-01

In the past few years, there are number of researchers carrying out their research on the excipients derived from polysaccharides and some of these researches show that natural excipients are comparable and can serve as an alternative to the synthetic excipients. Hence, the objectives of this research are to characterize the naturally sourced chickpea starch powder and to study the pharmaceutical excipient behavior of chickpea starch in gliclazide immediate release (IR) tablets. In this research, the binding properties of chickpea starch were compared to that of povidone, whereas the disintegrant properties of chickpea starch were compared to those of crospovidone, croscarmellose sodium and sodium starch glycolate. Flow property of chickpea starch was assessed with the measurement of bulk density, tapped density, compressibility index and angle of repose. Calibration curve for gliclazide in phosphate buffer pH 7.4 was developed. Gliclazide IR tablets were then produced with direct compression method. Physicochemical characteristics of the tablets, including thickness, tablet weight uniformity, hardness, disintegration time and friability were evaluated. Then, in vitro dissolution studies were performed by following United States Pharmacopeia (USP) dissolution method. The dissolution results were analyzed and compared with t30, t50, dissolution efficiency (DE). Lastly, drug-excipient compatibility studies, including Fourier transform infrared (FTIR) spectroscopic analysis and differential scanning calorimetric (DSC) analysis were carried out. Fair flow property was observed in the chickpea starch powder. Furthermore, the tablets produced passed all the tests in physicochemical characteristics evaluation except hardness and disintegration test. Additionally, in vitro dissolution studies show that chickpea starch acted as a disintegrant instead of a binder in gliclazide IR tablets and its disintegrant properties were comparable to those of crospovidone, croscarmellose sodium and sodium starch glycolate. Besides that, gliclazide was also compatible with the excipients used. Chickpea starch acted as a disintegrant in gliclazide IR tablets, instead of a binder. Therefore, chickpea starch can be a promising disintegrant in gliclazide IR tablets.

Martian airfall dust on smooth, inclined surfaces as observed on the Phoenix Mars Lander telltale mirror

NASA Astrophysics Data System (ADS)

Moores, John E.; Ha, Taesung; Lemmon, Mark T.; Gunnlaugsson, Haraldur Páll

2015-10-01

The telltale mirror, a smooth inclined surface raised over 1 m above the deck of the Phoenix Mars Lander, was observed by the Surface Stereo Imager (SSI) several times per sol during the Phoenix Mars Lander mission. These observations were combined with a radiative transfer model to determine the thickness of dust on the wind telltale mirror as a function of time. 239 telltale sequences were analyzed and dustiness was determined on a diurnal and seasonal basis. The thickness of accumulated dust did not follow any particular diurnal or seasonal trend. The dust thickness on the mirror over the mission was 0.82±0.39 μm, which suggests a similar thickness to the modal scattering particle diameter. This suggests that inclining a surface beyond the angle of repose and polishing it to remove surface imperfections is an effective way to mitigate the accumulation of dust to less than a micron over a wide range of meteorological conditions and could be beneficial for surfaces which can tolerate some dust but not thick accumulations, such as solar panels. However, such a surface will not remain completely dust free through this action alone and mechanical or electrical clearing must be employed to remove adhered dust if a pristine surface is required. The single-scattering phase function of the dust on the mirror was consistent with the single-scattering phase function of martian aerosol dust at 450 nm, suggesting that this result is inconsistent with models of the atmosphere which require vertically or horizontally separated components or broad size distributions to explain the scattering behavior of these aerosols in the blue. The single-scattering behavior of the dust on the mirror is also consistent with Hapke modeling of spherical particles. The presence of a monolayer of particles would tend to support the spherical conclusion: such particles would be most strongly adhered electrostatically.

GEOMETRIC, VOLUMETRIC, COLOUR AND FRICTIONAL PROPERTIES OF SELECTED SALVIA SPECIES OF TURKEY.

PubMed

Bayram, Mustafa; Altuntas, Ebubekir; Yilar, Melih

2017-01-01

Salvia seeds are promite to dietary and healthy oils because they contain essential fatty acids. Salvia seeds frequently produce mucilage on soaking, and this mucilage is used for the treatment of eye diseases in eastern countries. Salvia species studied for medicine, food and cosmetics, have the potential to be used in the various fields. In the present study, selected engineering (geometrical, volumetrical, colour and frictional) properties of 6 Salvia species seeds were determined and compared. This study was performed on selected engineering properties of seeds of 6 Salvia species ( Salvia viridis L., Salvia aethiopis L., Salvia cryptantha Montbert & Aucher ex Benthan., Salvia tomentosa Mill ., Salvia sclarea L., Salvia virgata Jacq.,) cultivated in Turkey. Plants were collected during the vegetation in 2012-2013 (May-Agust). The seeds were cleaned from foreign matter, dirt and broken seeds manually. The average length, width and thickness were found in the range of 2.61 to 3.53 mm, 1.59 to 2.92 mm and 1.14 to 2.52 mm, respectively. Salvia viridis L. specie had the lowest geometric mean diameter and surface area, whereas Salvia cryptantha L. had the least values among these 6 Salvia species for these properties. The bulk density, true density and the porosity were between 296.83 and 702.80 kg m -3 , 285.69 and 718.08 kg m -3 , 10.27 and 44.05%, respectively. The volume of unit seed and sphericity ranged between 2.56 and 13.64 mm 3 , 62.90 and 90.40%, respectively. The coefficient of friction of salvia species were largely influenced by the friction surfaces studied, and highest values were found for polywood in the Salvia crytantha L.. In the study, the static friction coefficient and the angle of repose of salvia species changed from 0.477 to 0.955, and from 14.09 to 23.57°, respectively. Determination of geometric, volumetric, colour and frictional properties of Salvia spp. seeds may increase their economic value.

The sample handling system for the Mars Icebreaker Life mission: from dirt to data.

PubMed

Davé, Arwen; Thompson, Sarah J; McKay, Christopher P; Stoker, Carol R; Zacny, Kris; Paulsen, Gale; Mellerowicz, Bolek; Glass, Brian J; Willson, David; Bonaccorsi, Rosalba; Rask, Jon

2013-04-01

The Mars Icebreaker Life mission will search for subsurface life on Mars. It consists of three payload elements: a drill to retrieve soil samples from approximately 1 m below the surface, a robotic sample handling system to deliver the sample from the drill to the instruments, and the instruments themselves. This paper will discuss the robotic sample handling system. Collecting samples from ice-rich soils on Mars in search of life presents two challenges: protection of that icy soil--considered a "special region" with respect to planetary protection--from contamination from Earth, and delivery of the icy, sticky soil to spacecraft instruments. We present a sampling device that meets these challenges. We built a prototype system and tested it at martian pressure, drilling into ice-cemented soil, collecting cuttings, and transferring them to the inlet port of the SOLID2 life-detection instrument. The tests successfully demonstrated that the Icebreaker drill, sample handling system, and life-detection instrument can collectively operate in these conditions and produce science data that can be delivered via telemetry--from dirt to data. Our results also demonstrate the feasibility of using an air gap to prevent forward contamination. We define a set of six analog soils for testing over a range of soil cohesion, from loose sand to basalt soil, with angles of repose of 27° and 39°, respectively. Particle size is a key determinant of jamming of mechanical parts by soil particles. Jamming occurs when the clearance between moving parts is equal in size to the most common particle size or equal to three of these particles together. Three particles acting together tend to form bridges and lead to clogging. Our experiments show that rotary-hammer action of the Icebreaker drill influences the particle size, typically reducing particle size by ≈ 100 μm.

Microencapsulation of bioactive principles with an airless spray-gun suitable for processing high viscous solutions.

PubMed

Cocchietto, Moreno; Blasi, Paolo; Lapasin, Romano; Moro, Chiara; Gallo, Davide; Sava, Gianni

2013-11-19

to design, assemble and test a prototype of a novel production plant, suitable for producing microparticles (MPs) by processing highly viscous feed solutions (FSs). the prototype has been built using a commercial air compressor, a piston pump, an airless spray-gun, a customized air-treatment section, a timer, a rotating base, and a filtration section. Preliminary prototype parameter setting was carried out to individuate the best performing nozzle's dimension, the nebulization timing, and the CaCl2 concentration in the gelation fluid. In addition, prototype throughput (1 L to 5 L) and the range of practicable feed solution (FS) viscosities were assayed. A set of four batches was prepared in order to characterize the MPs, in terms of mean particle size and distribution, flow properties, swelling, encapsulation efficiency and release. according to a qualitative scoring, the large nozzle was suitable to nebulize FSs at a higher alginate concentration. Conversely, the small nozzle performed better in the processing of FSs with an alginate concentration up to 2% w/v. Only at the highest degree of viscosity, corresponding to 5% w/v of alginate, the FS processing was not technically possible. Among the CaCl2 concentrations considered, 15% w/v was recognized as the most versatile. The prototype appears to be convenient and suitable to grant a high yield starting from 2 L of FS. The flow behavior of the FSs assayed can be satisfactorily described with the Carreau-Yasuda equation and the throughput begins to slightly decrease for FSs at alginate concentrations exceeding 3% w/v. MP morphology was irregular with crumpled shape. The angle of repose indicates a good flowability and the release studies showed gastro-resistance and potential prolonged release applications. the novel prototype of production plant is suitable to process large amounts (2 L or more) of FSs, characterized by a high viscosity, to produce MPs suitable for bioactive principle delivery.

Microencapsulation of Bioactive Principles with an Airless Spray-Gun Suitable for Processing High Viscous Solutions

PubMed Central

Cocchietto, Moreno; Blasi, Paolo; Lapasin, Romano; Moro, Chiara; Gallo, Davide; Sava, Gianni

2013-01-01

Purpose: to design, assemble and test a prototype of a novel production plant, suitable for producing microparticles (MPs) by processing highly viscous feed solutions (FSs). Methods: the prototype has been built using a commercial air compressor, a piston pump, an airless spray-gun, a customized air-treatment section, a timer, a rotating base, and a filtration section. Preliminary prototype parameter setting was carried out to individuate the best performing nozzle’s dimension, the nebulization timing, and the CaCl2 concentration in the gelation fluid. In addition, prototype throughput (1 L to 5 L) and the range of practicable feed solution (FS) viscosities were assayed. A set of four batches was prepared in order to characterize the MPs, in terms of mean particle size and distribution, flow properties, swelling, encapsulation efficiency and release. Results: according to a qualitative scoring, the large nozzle was suitable to nebulize FSs at a higher alginate concentration. Conversely, the small nozzle performed better in the processing of FSs with an alginate concentration up to 2% w/v. Only at the highest degree of viscosity, corresponding to 5% w/v of alginate, the FS processing was not technically possible. Among the CaCl2 concentrations considered, 15% w/v was recognized as the most versatile. The prototype appears to be convenient and suitable to grant a high yield starting from 2 L of FS. The flow behavior of the FSs assayed can be satisfactorily described with the Carreau-Yasuda equation and the throughput begins to slightly decrease for FSs at alginate concentrations exceeding 3% w/v. MP morphology was irregular with crumpled shape. The angle of repose indicates a good flowability and the release studies showed gastro-resistance and potential prolonged release applications. Conclusions: the novel prototype of production plant is suitable to process large amounts (2 L or more) of FSs, characterized by a high viscosity, to produce MPs suitable for bioactive principle delivery. PMID:24956192

Vesta: A Geological Overview

NASA Astrophysics Data System (ADS)

Ralf, Jaumann; Russell, C. T.; Raymond, C. A.; Pieters, C. M.; Yingst, R. A.; Williams, D. A.; Buczkowski, D. L.; Schenk, P.; Denevi, B.; Krohn, K.; Stephan, K.; Roatsch, T.; Preusker, F.; Otto, K.; Mest, S. C.; Ammannito, E.; Blewett, D.; Carsenty, U.; DeSanctis, C. M.; Garry, W.; Hiesinger, H.; Keller, H. U.; Kersten, E.; Marchi, S.; Matz, K. D.; McCord, T. B.; McSween, H. Y.; Mottola, S.; Nathues, A.; Neukum, G.; O'Brien, D. P.; Schmedemann, N.; Scully, J. E. C.; Sykes, M. V.; Zuber, M. T.

2012-10-01

The Dawn spacecraft has collected over 28,000 images and a wealth of spectral data providing nearly complete coverage of Vesta’s surface with multiple views. These data enable analysis of Vesta’s diverse geology including impact craters of all sizes and unusual shapes, a variety of ejecta blankets, large troughs extending around the equatorial region, impact basins, enigmatic dark material, and considerable evidence for mass wasting and surface alteration features (1). Two large impact basins, Veneneia (400km) underlying the larger Rheasilvia basin (500km) dominate the south pole (1,2). Rheasilvia exhibits a huge central peak, with total relief of -22km to 19km, and steep scarps with mass wasting features. Vesta’s global tectonic patterns (two distinct sets of large troughs almost parallel to the equator) strongly correlate with the locations of the two south polar impact basins, and were likely created by their formation (1,3). Numerous unusual asymmetric impact craters and ejecta indicate the strong role of topographic slope in cratering processes on Vesta (1). Such very steep topographic slopes are near to the angle of repose; slope failures make resurfacing due to impacts and their associated gravitational slumping and seismic effects an important geologic process on Vesta (1). Outcrops in crater walls indicate reworked crustal material and impact melt in combination with clusters of pits that show thermal surface processes (4). Relatively dark material of still unknown origin is intermixed in the regolith layers and partially excavated by younger impacts yielding dark outcrops, rays and ejecta (1,5). Finally, Vesta’s surface is younger than expected (6). (1) Jaumann, et al., 2012, Science 336, 687-690; (2) Schenk et al., 2012, Science 336, 964-967; (3) Buczkowski, et al., 2012, GRL, submitted; (4) Denevi, et al., 2012, Science, submitted; (5) McCord, et al., 2012, Nature, submitted; (6) Marchi, et al., 2012, Science 336, 690-694.

Development of a novel niosomal system for oral delivery of Ginkgo biloba extract

PubMed Central

Jin, Ye; Wen, Jingyuan; Garg, Sanjay; Liu, Da; Zhou, Yulin; Teng, Lirong; Zhang, Weiyu

2013-01-01

Background The aim of this study was to develop an optimal niosomal system to deliver Ginkgo biloba extract (GbE) with improved oral bioavailability and to replace the conventional GbE tablets. Methods In this study, the film dispersion-homogenization method was used to prepare GbE niosomes. The resulting GbE niosome suspension was freeze-dried or spray-dried to improve the stability of the niosomes. GbE-loaded niosomes were formulated and characterized in terms of their morphology, particle size, zeta potential, entrapment efficiency, and angle of repose, and differential scanning calorimetry analysis was performed. In vitro release and in vivo distribution studies were also carried out. Results The particle size of the optimal delivery system prepared with Tween 80, Span 80, and cholesterol was about 141 nm. There was a significant difference (P < 0.05) in drug entrapment efficiency between the spray-drying method (about 77.5%) and the freeze-drying method (about 50.1%). The stability study revealed no significant change in drug entrapment efficiency for the GbE niosomes at 4°C and 25°C after 3 months. The in vitro release study suggested that GbE niosomes can prolong the release of flavonoid glycosides in phosphate-buffered solution (pH 6.8) for up to 48 hours. The in vivo distribution study showed that the flavonoid glycoside content in the heart, lung, kidney, brain, and blood of rats treated with the GbE niosome carrier system was greater than in the rats treated with the oral GbE tablet (P < 0.01). No flavonoid glycosides were detected in the brain tissue of rats given the oral GbE tablets, but they were detected in the brain tissue of rats given the GbE niosomes. Conclusion Niosomes are a promising oral system for delivery of GbE to the brain. PMID:23378764

Geomorphometric variability of "monogenetic" volcanic cones: Evidence from Mauna Kea, Lanzarote and experimental cones

NASA Astrophysics Data System (ADS)

Kervyn, M.; Ernst, G. G. J.; Carracedo, J.-C.; Jacobs, P.

2012-01-01

Volcanic cones are the most common volcanic constructs on Earth. Their shape can be quantified using two morphometric ratios: the crater/cone base ratio (W cr/W co) and the cone height/width ratio (H co/W co). The average values for these ratios obtained over entire cone fields have been explained by the repose angle of loose granular material (i.e. scoria) controlling cone slopes. The observed variability in these ratios between individual cones has been attributed to the effect of erosional processes or contrasting eruptive conditions on cone morphometry. Using a GIS-based approach, high spatial resolution Digital Elevation Models and airphotos, two new geomorphometry datasets for cone fields at Mauna Kea (Hawaii, USA) and Lanzarote (Canary Islands, Spain) are extracted and analyzed here. The key observation in these datasets is the great variability in morphometric ratios, even for simple-shape and well-preserved cones. Simple analog experiments are presented to analyze factors influencing the morphometric ratios. The formation of a crater is simulated within an analog cone (i.e. a sand pile) by opening a drainage conduit at the cone base. Results from experiments show that variability in the morphometric ratios can be attributed to variations in the width, height and horizontal offset of the drainage point relative to the cone symmetry axis, to the dip of the underlying slope or to the influence of a small proportion of fine cohesive material. GIS analysis and analog experiments, together with specific examples of cones documented in the field, suggest that the morphometric ratios for well-preserved volcanic cones are controlled by a combination of 1) the intrinsic cone material properties, 2) time-dependent eruption conditions, 3) the local setting, and 4) the method used to estimate the cone height. Implications for interpreting cone morphometry solely as either an age or as an eruption condition indicator are highlighted.

MINErosion 3: Using measurements on a tilting flume-rainfall simulator facility to predict erosion rates from post-mining landscapes in Central Queensland, Australia

PubMed Central

Khalifa, Ashraf M.; Yu, Bofu; Caroll, Chris; Burger, Peter; Mulligan, David

2018-01-01

Open-cut coal mining in Queensland results in the formation of extensive saline overburden spoil-piles with steep slopes at the angle of repose (approximately 75% or 37o). These spoil-piles are generally found in multiple rows, several kilometers in length and heights of up to 50 or 60 m above the original landscape. They are highly dispersive and erodible. Legislation demands that these spoil piles be rehabilitated to minimize on-site and off-site discharges of sediment and salt into the surrounding environment. To achieve this, the steep slopes must be reduced, stabilized against erosion, covered with topsoil and re-vegetated. Key design criteria (slope gradient, slope length and vegetation cover) are required for the construction of post-mining landscapes that will result in acceptable erosion rates. A novel user-friendly hillslope computer model MINErosion 3.4 was developed that can accurately predict potential erosion rates from field scale hillslopes using parameters measured with a 3m laboratory tilting flume-rainfall simulator or using routinely measured soil physical and chemical properties. This model links MINErosion 2 with a novel consolidation and above ground vegetation cover factors, to the RUSLE and MUSLE equations to predict the mean annual and storm event erosion rates. The RUSLE-based prediction of the mean annual erosion rates allow minesites to derive the key design criteria of slope length, slope gradient and vegetation cover that would lead to acceptable erosion rates. The MUSLE-based prediction of storm event erosion rates will be useful as input into risk analysis of potential damage from erosion. MINErosion 3.4 was validated against erosion measured on 20 m field erosion plots established on post-mining landscapes at the Oakey Creek and Curragh coalmines, as well as on 120 and 70 m erosion plots on postmining landscapes at Kidston Gold Mine. PMID:29590190

MINErosion 3: Using measurements on a tilting flume-rainfall simulator facility to predict erosion rates from post-mining landscapes in Central Queensland, Australia.

PubMed

So, Hwat Bing; Khalifa, Ashraf M; Yu, Bofu; Caroll, Chris; Burger, Peter; Mulligan, David

2018-01-01

Open-cut coal mining in Queensland results in the formation of extensive saline overburden spoil-piles with steep slopes at the angle of repose (approximately 75% or 37o). These spoil-piles are generally found in multiple rows, several kilometers in length and heights of up to 50 or 60 m above the original landscape. They are highly dispersive and erodible. Legislation demands that these spoil piles be rehabilitated to minimize on-site and off-site discharges of sediment and salt into the surrounding environment. To achieve this, the steep slopes must be reduced, stabilized against erosion, covered with topsoil and re-vegetated. Key design criteria (slope gradient, slope length and vegetation cover) are required for the construction of post-mining landscapes that will result in acceptable erosion rates. A novel user-friendly hillslope computer model MINErosion 3.4 was developed that can accurately predict potential erosion rates from field scale hillslopes using parameters measured with a 3m laboratory tilting flume-rainfall simulator or using routinely measured soil physical and chemical properties. This model links MINErosion 2 with a novel consolidation and above ground vegetation cover factors, to the RUSLE and MUSLE equations to predict the mean annual and storm event erosion rates. The RUSLE-based prediction of the mean annual erosion rates allow minesites to derive the key design criteria of slope length, slope gradient and vegetation cover that would lead to acceptable erosion rates. The MUSLE-based prediction of storm event erosion rates will be useful as input into risk analysis of potential damage from erosion. MINErosion 3.4 was validated against erosion measured on 20 m field erosion plots established on post-mining landscapes at the Oakey Creek and Curragh coalmines, as well as on 120 and 70 m erosion plots on postmining landscapes at Kidston Gold Mine.

Polysaccharides obtained from bamboo shoots (Chimonobambusa quadrangularis) processing by-products: New insight into ethanol precipitation and characterization.

PubMed

Zhang, Fusheng; Ran, ChunXia; Zheng, Jiong; Ding, Yongbo; Chen, Guangjing

2018-06-01

Chimonobambusa quadrangularis polysaccharides (CPS) were extracted by ultrasonic-assisted extraction from bamboo shoots (C. quadrangularis) processing by-products. Three polysaccharide fractions, CPS70, CPS75 and CPS80, were obtained by precipitation at final ethanol concentrations of 70%, 75% and 80%, respectively. The physicochemical characterization and chemical antioxidant activities of the three polysaccharide fractions were compared on the basis of HPLC, FT-IR, XRD, TGA, and antioxidant measurements in vitro. The results suggested that ethanol concentrations used for precipitation of CPS can affect its physicochemical and associated functional properties, and antioxidant activities. Compared with CPS70 and CPS80, CPS75 had lower glucose content, higher total sugar content, and higher protein and uronic acid contents. The CPS70 and CPS80 were composed of Man, Rha, GlcA, Glc, Gal, Xyl and Ara, but none of them were found to contain GalA. In contrast, CPS75 consisted of Man, Rha, GlcA, GalA, Glc, Gal, Xyl and Ara. CPS75 had the lowest medium-high-molecular-weight value (116.53-118.18kDa) and the highest medium-low-molecular-weight value (21.30-22.68kDa). Meanwhile, CPS75 exhibited better functional properties including the repose angle, swelling capacity (SC), water retention capacity (WRC), and oil retention capacity (ORC). Moreover, CPS75 possessed higher scavenging capacities on DPPH, hydroxyl and ABTS radicals, higher oxygen radical absorbance capacity (OARC), higher metal chelating activity, and more significant reducing power. According to the results above, a final ethanol concentration of 75% could be chose to precipitate polysaccharides from bamboo shoots (C. quadrangularis) processing by-products. In summary, it is strongly recommended that the ethanol concentration employed in precipitation of natural polysaccharides could be optimized in advance. Copyright © 2018 Elsevier B.V. All rights reserved.

The influence of lip form on incisal display with lips in repose on the esthetic preferences of dentists and lay people.

PubMed

Kim, Jee; Topolski, Richard; Dickinson, Douglas; Ramos, Van

2017-09-01

Information is lacking for viewer preferences for incisal display with lips in repose. The purpose of this online survey was to establish measurement parameters to classify and define a lip form and to evaluate the influence of lip form on dentists' and laypersons' preferences for the amount of incisal display with lips in repose. Computer-generated male and female models were created using 3 different lip forms each, straight, moderate, and high. Three images of these models (frontal full face, zoomed-in frontal around the mouth, and oblique zoomed-in image of the mouth) were arranged in an interactive survey that was disseminated on the Websites Facebook, Instagram, DentalTown and by word-of-mouth. Respondents manipulated the incisal display of all 3 images in unison, using a slide bar, and the resulting incisal display was measured in millimeters and served as the primary dependent measure. Survey demographic data were obtained from an online survey site. Data were assessed for skewness, kurtosis, and outliers and analyzed with 5-way ANOVA: 2 sex levels for model, 2 levels for sex of respondent, 3 levels for lip height, 3 levels for occupation, and 5 levels of ethnicity, with multiple comparisons corrected with Bonferroni adjustments and post hoc comparisons performed using the Scheffé test (α=.05 for all comparisons). A total of 1039 individuals consented to the study. A final sample size of 687 respondents was obtained after excluding 352 who failed to complete the survey. The results indicated that lip form affected the esthetic perception of incisal display significantly (P<.001), with a preference for a greater amount of incisal display corresponding with increasing lip forms. Sex of the model was also significant, with greater incisal display being preferred for female faces. A significant difference was found for respondents' ethnicity, with African Americans generally preferring smaller incisal displays than other ethnic groups. No other main effects were found to be statistically significant. Only 2 interactions were shown to be statistically significant. Post hoc tests examining the interaction between lip form and sex of model showed a preference for greater incisal displays for female faces with high lip forms. A 3-way interaction was observed between lip form, sex of respondent, and occupation. Significant differences were identified for the 3 different lip forms for both sexes of models. As the lip form changed from straight to moderate to high, there was a preference for increased incisal display. Incisal display preferences for male and female models were the same for all respondents, except for the high lip form, for which a greater amount of incisal display was preferred for the female model. Sex and occupation of respondent failed to produce main effects. Respondents' ethnicity was shown to be statistically significant, with African Americans generally preferring shorter incisal displays. Copyright © 2016 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

Association maladie cœliaque et tuberculose multifocale: à propos d’un cas avec revue de la littérature

PubMed Central

Sarghini, Khadija; Oubaha, Sofia; Samlani, Zouhour; Krati, Khadija

2017-01-01

La maladie cœliaque est une entéropathie auto-immune liée à l'intolérance au Gluten qui survient sur un terrain génétiquement prédisposé. Le diagnostic repose sur la combinaison d'arguments cliniques, biologiques et histologiques. Elle est associée à de nombreuses complications, notamment le lymphome. Le risque de tuberculose chez les patients cœliaques est augmenté. Plusieurs hypothèses expliquant cette association ont été discutées. Nous rapportons un cas de maladie cœliaque associée à la tuberculose multifocale chez une patiente âgée de 17 ans. PMID:28979616

The December 4, 1983 to February 18, 1984 eruption of Piton de la Fournaise (La Reunion, Indian Ocean): Description and interpretation

NASA Astrophysics Data System (ADS)

Lénat, Jean-François; Bachèlery, Patrick; Bonneville, Alain; Tarits, Pascal; Cheminée, Jean-Louis; Delorme, Hugues

1989-01-01

On December 4, 1983 an eruption started at vents located 1.5 km southwest of the summit of Piton de la Fournaise at the base of the central cone. After 31 months of quiescence this was one of the longest repose period in the last fifty years. The eruption had two phases: December 4 to January 18 and January 18 to February 18. Phase 1 produced about 8 × 10 6 m 3 of lava and Phase II about 9 × 10 6 m 3. The erupted lava is an aphyric basalt whose mineralogical and geochemical composition is close to that of other lavas emitted since 1977. The precursors of the December 4 outbreak were limited to two-week shallow (1.5-3 km) seismic crisis of fewer than 50 events. No long-term increase was noted in the local seismicity which is very quiet during repose periods and no long-term ground inflation preceded the eruption. Outbreaks of Phases I and II were preceded by short (2.5 hours and 1.5 hours) seismic swarms corresponding to the rise of magma toward the surface from a shallow reservoir. Large ground deformation explained by the emplacement of the shallow intrusions, was recorded during the seismic swarms. A summit inflation was observed in early January, before the phase II outbreak, while the phase I eruption was still continuing. Piton de la Fournaise volcanological observatory was installed in 1980. Seismic and ground deformation data now available for a period of 4 years including the 1981 and the 1983-1984 eruptions, allow us to describe the physical behavior of the volcano during this period. These observations lead us to propose that the magma transfer from deep levels to the shallow magma reservoir is not a continuous process but a periodic one and that the shallow magma reservoir was not resupplied before the 1981 and 1983-1984 eruptions. Considerations on the eruptive history and the composition of recent lavas indicate that the reservoir was refilled in 1977.

Storage and interaction of compositionally heterogeneous magmas from the 1986 eruption of Augustine Volcano, Alaska

USGS Publications Warehouse

Roman, Diana C.; Cashman, Katharine V.; Gardner, Cynthia A.; Wallace, Paul J.; Donovan, John J.

2006-01-01

Compositional heterogeneity (56–64 wt% SiO2 whole-rock) in samples of tephra and lava from the 1986 eruption of Augustine Volcano, Alaska, raises questions about the physical nature of magma storage and interaction beneath this young and frequently active volcano. To determine conditions of magma storage and evolutionary histories of compositionally distinct magmas, we investigate physical and chemical characteristics of andesitic and dacitic magmas feeding the 1986 eruption. We calculate equilibrium temperatures and oxygen fugacities from Fe-Ti oxide compositions and find a continuous range in temperature from 877 to 947°C and high oxygen fugacities (ΔNNO=1–2) for all magmas. Melt inclusions in pyroxene phenocrysts analyzed by Fourier-transform infrared spectroscopy and electron probe microanalysis are dacitic to rhyolitic and have water contents ranging from <1 to ∼7 wt%. Matrix glass compositions are rhyolitic and remarkably similar (∼75.9–76.6 wt% SiO2) in all samples. All samples have ∼25% phenocrysts, but lower-silica samples have much higher microlite contents than higher-silica samples. Continuous ranges in temperature and whole-rock composition, as well as linear trends in Harker diagrams and disequilibrium mineral textures, indicate that the 1986 magmas are the product of mixing between dacitic magma and a hotter, more mafic magma. The dacitic endmember is probably residual magma from the previous (1976) eruption of Augustine, and we interpret the mafic endmember to have been intruded from depth. Mixing appears to have continued as magmas ascended towards the vent. We suggest that the physical structure of the magma storage system beneath Augustine contributed to the sustained compositional heterogeneity of this eruption, which is best explained by magma storage and interaction in a vertically extensive system of interconnected dikes rather than a single coherent magma chamber and/or conduit. The typically short repose period (∼10 years) between Augustine's recent eruptive pulses may also inhibit homogenization, as short repose periods and chemically heterogeneous magmas are observed at several volcanoes in the Cook Inlet region of Alaska.

Nested Architecture of Pyroclastic Bedforms Generated by a Single Flow Event: Outcrop Examples from the Izu Volcanic Islands, Japan

NASA Astrophysics Data System (ADS)

Nemoto, Y.; Yoshida, S.

2009-12-01

We claim that compound bedforms, where small bedforms (e.g., dunes and antidunes) occur within and around the larger bedforms, are common in pyroclastic-flow deposits, using Quaternary-Holocene outcrop examples from the modern Izu volcanic island chain some 100-150 km SSW of Tokyo. The nested occurrence of bedforms have been well documented for siliciclastic deposits, as exemplified by compound dunes where small dunes (c. cm- dm thick) occur between the avalanche surfaces within larger dunes, indicating that these dunes of different sizes were produced simultaneously. However, compound dunes have rarely been reported from pyroclastic deposits. In contrast, we have discovered that compound dunes are common in pyroclastic flow deposits in the late Pleistocene & Holocene outcrops in Niijima and Oshima of the Izu volcanic island chain. Moreover, these outcrops contain abundant compound antidunes, which have been reported from neither siliciclastic or pyroclastic deposits. This is probably because flume studies, where most of published antidune studies are based, focus on small (c. cm-dm high) antidunes. In Niijima Island, we examined pyroclastic-flow deposits shed from Mt. Miyatsuka (14 ka) and Mt. Mukai (886 A.D.). Both groups of deposits contain abundant antidune stratifications, which commonly form nested structures in a two- or three-fold hierarchy, with subordinate crossbeddings originated from dune migrations. Each class of antidunes is characterized by multiple scour surfaces and vertical aggradations around mounds of lag deposits above erosion surfaces, and typically has both upstream and downstream accretion components with different proportions. The late Pleistocene pyroclastic outcrops of the nearby Oshima Island exhibit similar patterns. The geometry of the accretion surfaces vary significantly in the outcrops of both Niijima and Oshima. Whereas the antidunes dominated by upstream accretion are characterized by (1) gently inclined accretion surface and (2) round crest shape, the antidunes dominated by downstream accretion are characterized by (i) steep accretion surface that commonly exceed the angle of repose and (ii) angular to cuspate crest shape. The mechanism in charge of generating the compound antidunes is unclear; however, observations of standing waves in the modern siliciclastic depositional environments (e.g., shallow running water on the beach) suggest that compound antidunes are produced by a gravitational collapse of the crest of large and exceedingly steepened standing waves. When the crest collapes, it commonly breaks into two smaller standing waves that are positioned on the flanks of the large (but now slightly deflated) standing wave, and stay there until the angle of the flanks increases again to form a new large standing wave. The collapse-rebuilding cycle persists as long as the flow condition is sustained.

[In the absence of early orthodontic treatment, is there a loss of chance?].

PubMed

Béry, A

2006-06-01

Chance is the probability that something will happen, and, in this sense, the absence of chance can be defined as the damage resulting from the disappearance of the probability of a favorable outcome (the contrary being the non-realization of the risk). This is autonomous damage that should be differentiated from final damage. Moral damage is a notion very close to the loss of chance even though it reposes on the indemnization of a final damage of an affection or malady. This article deals with these matters: an insufficient amount of information, the cause of final damage or the loss of chance, the loss of chance being a function of the deficit of information. In this sense, can the failure to begin early, appropriate dento-facial orthopedic treatment be considered a loss of chance for the child?

Lava fountain heights at Pu'u 'O'o, Kilauea, Hawaii - Indicators of amount and variations of exsolved magma volatiles

NASA Technical Reports Server (NTRS)

Head, James W., III; Wilson, Lionel

1987-01-01

Factors most important in determining fountain height in Hawaiian-type basaltic eruptions were assessed on the basis of theoretical calculations and observations at Pu'u 'O'o vent, east rift zone of Kilauea, Hawaii. It is shown that fountain height is very sensitive to changes in exsolved gas content (and, thus, can be used to estimate variability in exsolved gas content) and relatively insensitive to large variations in volume flux. Volume flux was found to be the most important parameter determining the equilibrium vent diameter. The results of calculations also indicate that there was a general increase in magma gas content over the first 20 episodes of the Pu'u 'O'o eruption and that gas depletion took place in the conduit beneath the vent during repose periods.

Beyond the angle of repose: A review and synthesis of landslide processes in response to rapid uplift, Eel River, Northern California

NASA Astrophysics Data System (ADS)

Roering, Joshua J.; Mackey, Benjamin H.; Handwerger, Alexander L.; Booth, Adam M.; Schmidt, David A.; Bennett, Georgina L.; Cerovski-Darriau, Corina

2015-05-01

In mountainous settings, increases in rock uplift are often followed by a commensurate uptick in denudation as rivers incise and steepen hillslopes, making them increasingly prone to landsliding as slope angles approach a limiting value. For decades, the threshold slope model has been invoked to account for landslide-driven increases in sediment flux that limit topographic relief, but the manner by which slope failures organize themselves spatially and temporally in order for erosion to keep pace with rock uplift has not been well documented. Here, we review past work and present new findings from remote sensing, cosmogenic radionuclides, suspended sediment records, and airborne lidar data, to decipher patterns of landslide activity and geomorphic processes related to rapid uplift along the northward-migrating Mendocino Triple Junction in Northern California. From historical air photos and airborne lidar, we estimated the velocity and sediment flux associated with active, slow-moving landslides (or earthflows) in the mélange- and argillite-dominated Eel River watershed using the downslope displacement of surface markers such as trees and shrubs. Although active landslides that directly convey sediment into the channel network account for only 7% of the landscape surface, their sediment flux amounts to more than 50% of the suspended load recorded at downstream sediment gaging stations. These active slides tend to exhibit seasonal variations in velocity as satellite-based interferometry has demonstrated that rapid acceleration commences within 1 to 2 months of the onset of autumn rainfall events before slower deceleration ensues in the spring and summer months. Curiously, this seasonal velocity pattern does not appear to vary with landslide size, suggesting that complex hydrologic-mechanical feedbacks (rather than 1-D pore pressure diffusion) may govern slide dynamics. A new analysis of 14 yrs of discharge and sediment concentration data for the Eel River indicates that the characteristic mid-winter timing of earthflow acceleration corresponds with increased suspended concentration values, suggesting that the seasonal onset of landslide motion each year may be reflected in the export of sediments to the continental margin. The vast majority of active slides exhibit gullied surfaces and the gully networks, which are also seasonally active, may facilitate sediment export although the proportion of material produced by this pathway is poorly known. Along Kekawaka Creek, a prominent tributary to the Eel River, new analyses of catchment-averaged erosion rates derived from cosmogenic radionuclides reveal rapid erosion (0.76 mm/yr) below a prominent knickpoint and slower erosion (0.29 mm/yr) upstream. Such knickpoints are frequently observed in Eel tributaries and are usually comprised of massive (> 10 m) interlocking resistant boulders that likely persist in the landscape for long periods of time (> 105 yr). Upstream of these knickpoints, active landslides tend to be less frequent and average slope angles are slightly gentler than in downstream areas, which indicates that landslide density and average slope angle appear to increase with erosion rate. Lastly, we synthesize evidence for the role of large, catastrophic landslides in regulating sediment flux and landscape form. The emergence of resistant blocks within the mélange bedrock has promoted large catastrophic slides that have dammed the Eel River and perhaps generated outburst events in the past. The frequency and impact of these landslide dams likely depend on the spatial and size distributions of resistant blocks relative to the width and drainage area of adjacent valley networks. Overall, our findings demonstrate that landslides within the Eel River catchment do not occur randomly, but instead exhibit spatial and temporal patterns related to baselevel lowering, climate forcing, and lithologic variations. Combined with recent landscape evolution models that incorporate landslides, these results provide predictive capability for estimating erosion rates and managing hazards in mountainous regions.

High rates of bedload transport measured from infilling rate of large strudelscour craters in the Beaufort Sea, Alaska

USGS Publications Warehouse

Reimnitz, Erk; Kempema, E.W.

1982-01-01

Strudel scours are craters as much as 20 m wide and 4 m deep, that are excavated by vertical drainage flow during the yearly spring flooding of vast reaches of fast ice surrounding arctic deltas; they form at a rate of about 2.5 km^-2 yr^-1. Monitoring two such craters in the Beaufort Sea, we found that in relatively unprotected sites they fill in by deposition from bedload in 2 to 3 years. Net westward sediment transport results in sand layers dipping at the angle of repose westward into the strudel-scour crater, whereas the west wall of the crater remains steep to vertical. Initially the crater traps almost all bedload: sand, pebbles, and organic detritus; as infilling progresses, the materials are increasingly winnowed, and bypassing must occur. Over a 20-m-wide sector, an exposed strudel scour trapped 360 m3 of bedload during two seasons; this infilling represents a bedload transport rate of 9 m3 yr^-1 m^-1. This rate should be applicable to a 4.5-km-wide zone with equal exposure and similar or shallower depth. Within this zone, the transport rate is 40,500 m3 yr^-1, similar to estimated longshore transport rates on local barrier beaches. On the basis of the established rate of cut and fill, all the delta-front deposits should consist of strudel-scour fill. Vibracores typically show dipping interbedded sand and lenses of organic material draped over very steep erosional contacts, and an absence of horizontal continuity of strata--criteria that should uniquely identify high-latitude deltaic deposits. Given a 2- to 3-year lifespan, most strudel scours seen in surveys must be old. The same holds true for ice gouges and other depressions not adjusted to summer waves and currents, although these features record events of only the past few years. In view of such high rates of bottom reworking of the shallow shelf, any human activities creating turbidity, such as dredging, would have little effect on the environment. However, huge amounts of transitory material trapped by long causeways planned for offshore development would result in major changes in the environment.

Small graben in the southeastern ejecta blanket of the lunar Copernicus crater: Implications for recent shallow igneous intrusion on the Moon

NASA Astrophysics Data System (ADS)

Xiao, Zhiyong; Huang, Qian; Zeng, Zuoxun; Xiao, Long

2017-12-01

Dozens of linear graben that are about 10-400 m wide and less than 1 km long are recognized in the southeastern continuous ejecta deposits of Copernicus, supporting that Copernican-aged tectonism has occurred on the Moon. Fault geometry analysis suggests that the bounding faults of the graben have formed within the ejecta deposits. The graben are exclusively located on a local high-relief area, but they are not formed by mass wasting, because the topographic slope is substantially less than the repose angle of typical lunar materials, and no other extensional structures are visible on similar high-relief areas at the continuous ejecta deposits of Copernicus. The orientations of the graben all point to the center of Copernicus, but the topography of Copernicus is little compensated after formation, suggesting that the graben were not caused by possible crustal isostatic readjustment. This graben system is one of the three examples on the Moon that were interpreted to be caused by shallow igneous intrusions in the format of laccoliths. The currently available GRAIL gravity data have a lower spatial resolution than the size of the graben, so the gravity data cannot resolve the hypothesized sub-kilometer-scale laccoliths beneath the graben. While laccolith intrusion to a depth of about 80 m is required to explain the formation of this graben system, the laccolith intrusion scenario is not consistent with the geological context of the graben. A compressional structure is visible close to the graben system, and their spatial configuration and similar preservation states are consistent with being generically related. A close examination of the other two sets of graben that were also interpreted to have no associated compressional structures actually reveals spatially-related lobate scarps and wrinkle ridges in the vicinity. Therefore, shallow igneous intrusion is not plausible or necessary to explain to formation of Copernican-aged graben on the Moon, and they are most likely formed by the late-stage global contraction of the Moon.

The Breakdown: Hillslope Sources of Channel Blocks in Bedrock Landscapes

NASA Astrophysics Data System (ADS)

Selander, B.; Anderson, S. P.; Rossi, M.

2017-12-01

Block delivery from hillslopes is a poorly understood process that influences bedrock channel incision rates and shapes steep terrain. Previous studies demonstrate that hillslope sediment delivery rate and grain size increases with channel downcutting rate or fracture density (Attal et al., 2015, ESurf). However, blocks that exceed the competence of the channel can inhibit incision. In Boulder Creek, a bedrock channel in the Colorado Front Range, large boulders (>1 m diameter) are most numerous in the steepest channel reaches; their distribution seems to reflect autogenic channel-hillslope feedback between incision rate and block delivery (Shobe et al., 2016, GRL). It is clear that the processes, rates of production, and delivery of large blocks from hillslopes into channels are critical to our understanding of steep terrain evolution. Fundamental questions are 1) whether block production or block delivery is rate limiting, 2) what mechanisms release blocks, and 3) how block production and transport affect slope morphology. As a first step, we map rock outcrops on the granodiorite hillslopes lining Boulder Creek within Boulder Canyon using a high resolution DEM. Our algorithm uses high ranges of curvature values in conjunction with slopes steeper than the angle of repose to quickly identify rock outcrops. We field verified mapped outcrop and sediment-mantled locations on hillslopes above and below the channel knickzone. We find a greater abundance of exposed rock outcrops on steeper hillslopes in Boulder Canyon. Additionally, we find that channel reaches with large in-channel blocks are located at the base of hillslopes with large areas of exposed bedrock, while reaches lacking large in-channel blocks tend to be at the base of predominately soil mantled and forested hillslopes. These observations support the model of block delivery and channel incision of Shobe et al. (2016, GRL). Moreover, these results highlight the conundrum of how rapid channel incision is sustained if large blocks inhibit channel incision. This work points to the need to understand mechanisms of block release, the fate of released blocks, and how both processes influence the evolution of rocky hillslopes.

Roller compaction: Effect of relative humidity of lactose powder.

PubMed

Omar, Chalak S; Dhenge, Ranjit M; Palzer, Stefan; Hounslow, Michael J; Salman, Agba D

2016-09-01

The effect of storage at different relative humidity conditions, for various types of lactose, on roller compaction behaviour was investigated. Three types of lactose were used in this study: anhydrous lactose (SuperTab21AN), spray dried lactose (SuperTab11SD) and α-lactose monohydrate 200M. These powders differ in their amorphous contents, due to different manufacturing processes. The powders were stored in a climatic chamber at different relative humidity values ranging from 10% to 80% RH. It was found that the roller compaction behaviour and ribbon properties were different for powders conditioned to different relative humidities. The amount of fines produced, which is undesirable in roller compaction, was found to be different at different relative humidity. The minimum amount of fines produced was found to be for powders conditioned at 20-40% RH. The maximum amount of fines was produced for powders conditioned at 80% RH. This was attributed to the decrease in powder flowability, as indicated by the flow function coefficient ffc and the angle of repose. Particle Image Velocimetry (PIV) was also applied to determine the velocity of primary particles during ribbon production, and it was found that the velocity of the powder during the roller compaction decreased with powders stored at high RH. This resulted in less powder being present in the compaction zone at the edges of the rollers, which resulted in ribbons with a smaller overall width. The relative humidity for the storage of powders has shown to have minimal effect on the ribbon tensile strength at low RH conditions (10-20%). The lowest tensile strength of ribbons produced from lactose 200M and SD was for powders conditioned at 80% RH, whereas, ribbons produced from lactose 21AN at the same condition of 80% RH showed the highest tensile strength. The storage RH range 20-40% was found to be an optimum condition for roll compacting three lactose powders, as it resulted in a minimum amount of fines in the product. Copyright © 2016 Elsevier B.V. All rights reserved.

GEOMETRIC, VOLUMETRIC, COLOUR AND FRICTIONAL PROPERTIES OF SELECTED SALVIA SPECIES OF TURKEY

PubMed Central

Bayram, Mustafa; Altuntas, Ebubekir; Yilar, Melih

2017-01-01

Background: Salvia seeds are promite to dietary and healthy oils because they contain essential fatty acids. Salvia seeds frequently produce mucilage on soaking, and this mucilage is used for the treatment of eye diseases in eastern countries. Salvia species studied for medicine, food and cosmetics, have the potential to be used in the various fields. In the present study, selected engineering (geometrical, volumetrical, colour and frictional) properties of 6 Salvia species seeds were determined and compared. Materials and Methods: This study was performed on selected engineering properties of seeds of 6 Salvia species (Salvia viridis L., Salvia aethiopis L., Salvia cryptantha Montbert & Aucher ex Benthan., Salvia tomentosa Mill., Salvia sclarea L., Salvia virgata Jacq.,) cultivated in Turkey. Plants were collected during the vegetation in 2012-2013 (May-Agust). The seeds were cleaned from foreign matter, dirt and broken seeds manually. Results: The average length, width and thickness were found in the range of 2.61 to 3.53 mm, 1.59 to 2.92 mm and 1.14 to 2.52 mm, respectively. Salvia viridis L. specie had the lowest geometric mean diameter and surface area, whereas Salvia cryptantha L. had the least values among these 6 Salvia species for these properties. The bulk density, true density and the porosity were between 296.83 and 702.80 kg m-3, 285.69 and 718.08 kg m-3, 10.27 and 44.05%, respectively. The volume of unit seed and sphericity ranged between 2.56 and 13.64 mm3, 62.90 and 90.40%, respectively. The coefficient of friction of salvia species were largely influenced by the friction surfaces studied, and highest values were found for polywood in the Salvia crytantha L.. In the study, the static friction coefficient and the angle of repose of salvia species changed from 0.477 to 0.955, and from 14.09 to 23.57°, respectively. Conclusion: Determination of geometric, volumetric, colour and frictional properties of Salvia spp. seeds may increase their economic value. PMID:28480423

An empirical model for transient crater growth in granular targets based on direct observations

NASA Astrophysics Data System (ADS)

Yamamoto, Satoru; Barnouin-Jha, Olivier S.; Toriumi, Takashi; Sugita, Seiji; Matsui, Takafumi

2009-09-01

The present paper describes observations of crater growth up to the time of transient crater formation and presents a new empirical model for transient crater growth as a function of time. Polycarbonate projectiles were impacted vertically into soda-lime glass sphere targets using a single-stage light-gas gun. Using a new technique with a laser sheet illuminating the target [Barnouin-Jha, O.S., Yamamoto, S., Toriumi, T., Sugita, S., Matsui, T., 2007. Non-intrusive measurements of the crater growth. Icarus, 188, 506-521], we measured the temporal change in diameter of crater cavities (diameter growth). The rate of increase in diameter at early times follows a power law relation, but the data at later times (before the end of transient crater formation) deviates from the power law relation. In addition, the power law exponent at early times and the degree of deviation from a power law at later times depend on the target. In order to interpret these features, we proposed to modify Maxwell's Z-model under the assumption that the strength of the excavation flow field decreases exponentially with time. We also derived a diameter growth model as: d(t)∝[1-exp(-βt)]γ, where d(t) is the apparent diameter of the crater cavity at time t after impact, and β and γ are constants. We demonstrated that the diameter growth model could represent well the experimental data for various targets with different target material properties, such as porosity or angle of repose. We also investigated the diameter growth for a dry sand target, which has been used to formulate previous scaling relations. The obtained results showed that the dry sand target has larger degree of deviation from a power law, indicating that the target material properties of the dry sand target have a significant effect on diameter growth, especially at later times. This may suggest that the previously reported scaling relations should be reexamined in order to account for the late-stage behavior with the effect of target material properties.

Seasonal Dark Streaks in Tivat Crater, Mars

NASA Image and Video Library

2017-11-20

This inner slope of a crater on southern Mars has several of the seasonal dark streaks called "recurrent slope lineae," or RSL, that a November 2017 report interprets as granular flows, rather than darkening due to flowing water. This 2011 view near the top of the southern rim of Tivat Crater comes from the High Resolution Imaging Science Experiment (HiRISE) camera on NASA's Mars Reconnaissance Orbiter. North is toward the top and the slope descends toward the northwest. The view spans an area about 1,000 feet (300 meters) wide. Figure 1 includes a scale bar of 50 meters (164 feet). HiRISE began viewing Mars in 2006. Multiple observations of some sites resulted in discovery of RSL in 2011 and has confirmed many thousands of them at more than 50 sites, from equatorial to mid-latitude north and south. These narrow, dark features appear in warm seasons, gradually extend downslope, fade away in winter and reappear the next year. On Earth, only seeping water is known to have these behaviors. Hydrated salts have been identified at RSL sites and RSL have previously been considered possible evidence of liquid water seeping down the slopes and darkening the ground. The Nov. 20, 2017, report in Nature Geosciences uses analysis of the steepness of slopes where RSL appear, including these RSL at Tivat Crater. The RSL all end, downhill, at approximately the same slope, which is similar to the angle of repose for sand. That is, the flows do not extend to slopes shallower than where dry grains of sand or dust could slip downhill, as on the face of a dune. Seeping water should readily extend to shallower slopes. This image is an excerpt from HiRISE observation ESP_023184_1335, taken on July 8, 2011, during Martian mid-afternoon at this site, at latitude 45.9 degrees south and longitude 9.5 degrees east. Tivat Crater is about 2.2 miles (3.6 kilometers) in diameter, and was named in 2011 for a town in Montenegro. https://photojournal.jpl.nasa.gov/catalog/PIA22070

A finite volume solver for three dimensional debris flow simulations based on a single calibration parameter

NASA Astrophysics Data System (ADS)

von Boetticher, Albrecht; Turowski, Jens M.; McArdell, Brian; Rickenmann, Dieter

2016-04-01

Debris flows are frequent natural hazards that cause massive damage. A wide range of debris flow models try to cover the complex flow behavior that arises from the inhomogeneous material mixture of water with clay, silt, sand, and gravel. The energy dissipation between moving grains depends on grain collisions and tangential friction, and the viscosity of the interstitial fine material suspension depends on the shear gradient. Thus a rheology description needs to be sensitive to the local pressure and shear rate, making the three-dimensional flow structure a key issue for flows in complex terrain. Furthermore, the momentum exchange between the granular and fluid phases should account for the presence of larger particles. We model the fine material suspension with a Herschel-Bulkley rheology law, and represent the gravel with the Coulomb-viscoplastic rheology of Domnik & Pudasaini (Domnik et al. 2013). Both composites are described by two phases that can mix; a third phase accounting for the air is kept separate to account for the free surface. The fluid dynamics are solved in three dimensions using the finite volume open-source code OpenFOAM. Computational costs are kept reasonable by using the Volume of Fluid method to solve only one phase-averaged system of Navier-Stokes equations. The Herschel-Bulkley parameters are modeled as a function of water content, volumetric solid concentration of the mixture, clay content and its mineral composition (Coussot et al. 1989, Yu et al. 2013). The gravel phase properties needed for the Coulomb-viscoplastic rheology are defined by the angle of repose of the gravel. In addition to this basic setup, larger grains and the corresponding grain collisions can be introduced by a coupled Lagrangian particle simulation. Based on the local Savage number a diffusive term in the gravel phase can activate phase separation. The resulting model can reproduce the sensitivity of the debris flow to water content and channel bed roughness, as illustrated with lab-scale and large-scale experiments. A large-scale natural landslide event down a curved channel is presented to show the model performance at such a scale, calibrated based on the observed surface super-elevation.

Carnauba wax as a promising excipient in melt granulation targeting the preparation of mini-tablets for sustained release of highly soluble drugs.

PubMed

Nart, Viviane; Beringhs, André O'Reilly; França, Maria Terezinha; de Espíndola, Brenda; Pezzini, Bianca Ramos; Stulzer, Hellen Karine

2017-01-01

Mini-tablets are a new tendency in solid dosage form design for overcoming therapeutic obstacles such as impaired swallowing and polypharmacy therapy. Among their advantages, these systems offer therapeutic benefits such as dose flexibility and combined drug release patterns. The use of lipids in the formulation has also drawn considerable interest as means to modify the drug release from the dosage form. Therefore, this paper aimed at developing sustained release mini-tablets containing the highly soluble drugs captopril and metformin hydrochloride. Carnauba wax was used as a lipid component in melt granulation, targeting the improvement of the drugs poor flowability and tabletability, as well as to sustain the drug release profiles in association with other excipients. To assist sustaining the drug release, Ethocel™ (EC) and Kollicoat® SR 30D associated with Opadry® II were employed as matrix-forming and reservoir-forming materials, respectively. The neat drugs, granules and the bulk formulations were evaluated for their angle of repose, compressibility index, Hausner ratio and tabletability. Mini-tablets were evaluated for their weight variation, hardness, friability, drug content and in-vitro drug release. The results indicated that melt granulation with carnauba wax improved the flow and the tabletability of the drugs, allowing the preparation of mini-tablets with adequate tensile strength under reduced compaction pressures. All mini-tablet formulations showed acceptable hardness (within the range of 1.16 to 3.93Kp) and friability (<0.1%). The melt-granulated captopril in matrix systems containing 50% EC (45P, 100P or 100FP) and the melt-granulated metformin hydrochloride in reservoir systems coated with Kollicoat® SR 30D and Opadry® II (80:20 with 10% weight gain or 70:30 with 20% weight gain) exhibited release profiles adequate to sustained release formulations, for over 450min. Therefore, carnauba wax proved to be a promising excipient in melt granulation targeting the preparation of mini-tablets for sustained release of soluble drugs. Copyright © 2016 Elsevier B.V. All rights reserved.

Steady state volcanism - Evidence from eruption histories of polygenetic volcanoes

NASA Technical Reports Server (NTRS)

Wadge, G.

1982-01-01

Cumulative volcano volume curves are presented as evidence for steady-state behavior at certain volcanoes and to develop a model of steady-state volcanism. A minimum criteria of five eruptions over a year was chosen to characterize a steady-state volcano. The subsequent model features a constant head of magmatic pressure from a reservoir supplied from depth, a sawtooth curve produced by the magma arrivals or discharge from the subvolcanic reservoir, large volume eruptions with long repose periods, and conditions of nonsupply of magma. The behavior of Mts. Etna, Nyamuragira, and Kilauea are described and show continuous levels of plasma output resulting in cumulative volume increases. Further discussion is made of steady-state andesitic and dacitic volcanism, long term patterns of the steady state, and magma storage, and the lack of a sufficient number of steady-state volcanoes in the world is taken as evidence that further data is required for a comprehensive model.

Thermal surveillance of volcanoes of the Cascade Range and Iceland utilizing ERTS DCP systems and imagery

NASA Technical Reports Server (NTRS)

Friedman, J. D. (Principal Investigator)

1973-01-01

The author has identified the following significant results. Significant results of the thermal surveillance of volcanoes experiment during 1972 included the design, construction, emplacement, and successful operation at volcanic sites in the Cascade Range, North America and on Surtsey, Iceland, of automated thermistor arrays which transmit ground and fumarole temperatures via the ERTS-1 data communication system to Goddard Space Flight Center. Temperature, radiance, and anomalous heat flow variations are being plotted by a U.S. Geological Survey IBM 360/65 computer program to show daily fluctuations at each of the sites. Results are being compiled in conjunction with NASA and USGS aircraft infrared survey data to provide thermal energy yield estimates during the current repose period of several Cascade Range volcanic systems. ERTS-1 MSS images have provided new information on the extent of structural elements controlling thermal emission at Lassen Volcanic National Park.

Foucault Retires to the Gym: Understanding Embodied Aging in the Third Age.

PubMed

Allain, Kristi A; Marshall, Barbara

2017-09-01

In light of recent social pressures leading to a reimagining of the "Third Age" as a time of constant activity rather than repose and relaxation, this article explores the pressure on individuals to age "successfully" by engaging in physical activity in later life. Through semi-structured interviews with 15 retired or semi-retired gym-goers (eight women and seven men), the article examines how this call to increased activity impacts the ways active mid-life and older adults understand themselves and others. Drawing on Foucault's understandings of the productive nature of power, we argue that those who perceive themselves as successfully heeding the call to active aging position themselves in contrast to inactive peers. Within a neoliberal framework, these participants self-identify as morally responsible citizens who, as a result of engagement in fitness activities, are authorized to survey and discipline the bodies of those "others" who will not or cannot engage in regular exercise.

Implications of magma transfer between multiple reservoirs on eruption cycling.

PubMed

Elsworth, Derek; Mattioli, Glen; Taron, Joshua; Voight, Barry; Herd, Richard

2008-10-10

Volcanic eruptions are episodic despite being supplied by melt at a nearly constant rate. We used histories of magma efflux and surface deformation to geodetically image magma transfer within the deep crustal plumbing of the Soufrière Hills volcano on Montserrat, West Indies. For three cycles of effusion followed by discrete pauses, supply of the system from the deep crust and mantle was continuous. During periods of reinitiated high surface efflux, magma rose quickly and synchronously from a deflating mid-crustal reservoir (at about 12 kilometers) augmented from depth. During repose, the lower reservoir refilled from the deep supply, with only minor discharge transiting the upper chamber to surface. These observations are consistent with a model involving the continuous supply of magma from the deep crust and mantle into a voluminous and compliant mid-crustal reservoir, episodically valved below a shallow reservoir (at about 6 kilometers).

Voluminous eruption from a zoned magma body after an increase in supply rate at Axial Seamount

NASA Astrophysics Data System (ADS)

Chadwick, W. W.; Paduan, J. B.; Clague, D. A.; Dreyer, B. M.; Merle, S. G.; Bobbitt, A. M.; Caress, D. W.; Philip, B. T.; Kelley, D. S.; Nooner, S. L.

2016-12-01

Axial Seamount is the best monitored submarine volcano in the world, providing an exceptional window into the dynamic interactions between magma storage, transport, and eruption processes in a mid-ocean ridge setting. An eruption in April 2015 produced the largest volume of erupted lava since monitoring and mapping began in the mid-1980s after the shortest repose time, due to a recent increase in magma supply. The higher rate of magma replenishment since 2011 resulted in the eruption of the most mafic lava in the last 500-600 years. Eruptive fissures at the volcano summit produced pyroclastic ash that was deposited over an area of at least 8 km2. A systematic spatial distribution of compositions is consistent with a single dike tapping different parts of a thermally and chemically zoned magma reservoir that can be directly related to previous multichannel seismic-imaging results.

A new method for determining acoustic-liner admittance in a rectangular duct with grazing flow from experimental data

NASA Technical Reports Server (NTRS)

Watson, W. R.

1984-01-01

A method is developed for determining acoustic liner admittance in a rectangular duct with grazing flow. The axial propagation constant, cross mode order, and mean flow profile is measured. These measured data are then input into an analytical program which determines the unknown admittance value. The analytical program is based upon a finite element discretization of the acoustic field and a reposing of the unknown admittance value as a linear eigenvalue problem on the admittance value. Gaussian elimination is employed to solve this eigenvalue problem. The method used is extendable to grazing flows with boundary layers in both transverse directions of an impedance tube (or duct). Predicted admittance values are compared both with exact values that can be obtained for uniform mean flow profiles and with those from a Runge Kutta integration technique for cases involving a one dimensional boundary layer.

Implementing AORN recommended practices for product selection.

PubMed

Conrardy, Julie A

2012-06-01

This article focuses on the revised AORN "Recommended practices for product selection in perioperative practice settings." Hospitals and ambulatory surgery facilities should have protocols in place for product evaluation that includes a multidisciplinary team approach. The process for product evaluation and selection includes gathering information; establishing consistent requirements for product evaluation; performing a financial impact analysis; investigating a plan to standardize products; conducting an environmental impact analysis; determining whether to purchase single-use, reposable, or reusable products or reprocess single-use devices; developing an evaluation process based on objective criteria; and developing and implementing a comprehensive plan to introduce and use new products. Use of an evaluation tool that is based on objective criteria is one way to obtain valuable input during product evaluations. Because of varied roles and experiences, the perioperative RN is an integral member of the product selection committee. Published by Elsevier Inc.

The extimated presence of differentiated higly explosive magmas beneath Vesuvius and Campi Flegrei: evidence from geochemical and textural studies.

NASA Astrophysics Data System (ADS)

Pappalardo, Lucia; Mastrolorenzo, Giuseppe

2010-05-01

Highly catastrophic explosive eruptions are supplied by Si-rich magmas, generated at shallower level in crust by the evolution of mantle liquids. The timescale of these evolution processes is a crucial factor, because of its control on the length of volcano repose interval leading to high explosive events. Campi Flegrei and Somma-Vesuvius alkaline volcanic systems, located respectively at few kilometers west and east of Neapolitan metropolitan area, produced a variety of eruptions ranging from not explosive lava flows and domes to highly destructive eruptions. Both these high risk volcanoes are in repose time since the last eruption occurred in the 1538 and 1944 BP, respectively. Since that time, the volcanoes experienced fumarolic activity, low level of seismicity with rare earthquakes swarms, as well as two bradyseismic crisis (1969-1972 and 1982-1984) localized in the center of Campi Flegrei caldera, that generated a net uplift of 3.5 m around the town of Pozzuoli. A wide low velocity layer interpreted as an extended magmatic body has been detected at 8-10 km depth beneath these volcanoes by seismic data. The capability of this reservoir to erupt explosively again strongly depends on magma differentiation degree, therefore the knowledge of the time lapse necessary at not explosive mafic liquids to differentiate toward explosive magmas is very crucial to predict the size of a possible short-term future eruption in Campanian area. Our petrologic data indicate that a multi-depth supply system was active under the Campanian Plain since 39 ka. Fractional crystallization during magma cooling associated with upward migration of less dense evolved liquids appears to be the prevalent differentiation process. Our results indicate that huge steam exolution occurred during the late stage of trachyte and phonolite crystallization thus accounting for the high Volcanic Explosivity Index (VEI) of eruptions supplied by these melts. Moreover our CSD data on phenocrysts reveal rapid crystallization and differentiation time for alkaline Campanian magmas (in the order of decades to few centuries). This evidence implies that the 400 km2 partial melting zone detected by tomography study at 8-10 km depth beneath Vesuvius and Campi Flegrei, should consist of differentiated magma already capable to produce also large scale (plinian) explosive events in case of renewal of the activity from the present closed-conduit state.

Equilibrium and Disequilibrium of 230Th-238U in Zircon from the Minoan Eruption, Santorini, Aegean Sea, Greece

NASA Astrophysics Data System (ADS)

Schmitt, A. K.; Stockli, D. F.; Song, E. J.; Storm, S.

2016-12-01

The Minoan eruption (ca. 1600 BCE; 40-80 km3 dense rock equivalent) occurred after a ca. 18 ka period of dormancy followed by rapid reinvigoration through arrival of new magma from deep reservoirs colliding with evolved magmas in shallow storage. Although zoned phenocrysts indicate brief timescales ranging between years to decades for final pre-eruptive magma recharge and mixing, it remains unclear how magma accumulation vs. crystallization were balanced in the subvolcanic reservoir during the preceding inter-eruptive cycle. To directly probe magma presence over the repose interval prior to the Minoan eruption and further back in time, we reconnoitered the potential of U-Th zircon geochronology to date the crystallization of individual zircon crystals from pumice from the Minoan eruption. Zircon crystals were extracted from composite pumice samples (several kg each) from basal fall out deposits using gravity and magnetic separation. Etching in cold HF removed adherent glass and revealed the shape of crystals, which were pressed into indium metal to expose unpolished rims to the ion beam of a CAMECA IMS 1270 secondary ionization mass spectrometer. Adherent glass was ubiquitous, indicating that crystals were in contact with melt at the time of eruption. Six of 18 crystals were in 230Th/238U secular equilibrium, two crystals yielded ages of ca. 160 ka, and the remaining rims dated between eruption age and ca. 20 ka. Low Th/U of some secular equilibrium zircon suggests recycling of metamorphic basement zircon, which is also indicated by the presence of rutile in heavy mineral separates. U-Th dates also reveal recycling of zircon from Pleistocene intrusions that likely represent left-over magma from antecedent eruption cycles. We tentatively interpret the dominant zircon population with near-eruption to ca. 20 ka ages to indicate continuous melt presence underneath Santorini during the last repose interval. Distinguishing a hiatus in zircon crystallization between 20 ka and 160 ka from continuous presence of a crystal mush capable of crystallizing zircon throughout the late Pleistocene requires further analyses. A corollary of mixed zircon populations of heterogeneous provenance in Minoan pumice is that the age significance of U-series data for major phases analyzed in bulk is suspect.

Le leadership en santé et la philosophie appliquée : une ressource essentielle.

PubMed

Fistein, Elizabeth; Malloy, David Cruise

2017-07-01

En qualité de professionnels de la santé, nous sommes déterminés à assurer l'exploitation efficiente et efficace de nos établissements. Les outils dont nous disposons sont les structures bureaucratiques, les règles, les règlements, les politiques et, bien sûr, les mesures. Il n'y a rien de foncièrement pernicieux à avoir des établissements efficients, efficaces et mesurés, mais nous soutenons que l'humanité et l'authenticité manquent cruellement dans cet environnement, au prix d'un travail significatif. Les solutions que nous proposons appartiennent au milieu de la philosophie, et particulièrement au secteur qui repose sur des principes fondamentaux : qu'est-ce qu'une infirmière, qu'est-ce qu'un patient, qu'est-ce qu'un hôpital?

Bedform development in mixed sand-mud: The contrasting role of cohesive forces in flow and bed

NASA Astrophysics Data System (ADS)

Baas, Jaco H.; Davies, Alan G.; Malarkey, Jonathan

2013-01-01

The majority of subaqueous sediment on Earth consists of mixtures of cohesive clay and cohesionless sand and silt, but the role of cohesion on the development and stability of sedimentary bedforms is poorly understood. The results of new laboratory flume experiments on bedform development in cohesive, mixed sand-mud beds are compared with the results of previous experiments in which cohesive forces in high concentration clay flows dominated bedform development. Even though both series of mixed sand-mud experiments were conducted at similar flow velocities, the textural and structural properties of the bedforms were sufficiently different to permit the designation of key criteria for identifying bedform generation under cohesive flows against bedform generation on cohesive substrates. These criteria are essential for improving bedform size predictions in sediment transport modelling in modern sedimentary environments and for the reconstruction of depositional processes in the geological record. The current ripples developing on the cohesive, mixed sand-mud beds, with bed mud fractions of up to 18%, were significantly smaller than equivalent bedforms in noncohesive sand. Moreover, the bedform height showed a stronger inversely proportional relationship with initial bed mud fraction than the bedform wavelength. This is in contrast with the bedforms developing under the cohesive clay flows, which tend to increase in size with increasing suspended clay concentration until the flow turbulence is fully suppressed. Selective removal of clay from the mixed beds, i.e., clay winnowing, was found to be an important process, with 82-100% clay entrained into suspension after 2 h of bedform development. This winnowing process led to the development of a sand-rich armouring layer. This armouring layer is inferred to have protected the underlying mixed sand-mud from prolonged erosion, and in conjunction with strong cohesive forces in the bed may have caused the smaller size of the bedforms. Winnowing was less efficient for the bedforms developing under the cohesive clay flows, where bedforms consisting of muddy sand were more characteristic. The winnowed sand was also found to heal irregularly scoured topography, thus reestablishing classic quasitriangular bedform shapes. In cohesive flows, the bedforms had more variable shapes, and the healing process was confined to lower transitional plug flows in which strong turbulence is only present close to the sediment bed. Furthermore, the bedforms on the cohesive beds tended to form angle-of-repose cross lamination, whereas low angle cross lamination was more common in bedforms under cohesive flows. In general terms, erosional bedforms prevail when cohesive forces in the bed dominate bedform dynamics, whereas depositional bedforms prevail when cohesive forces in the flow dominate bedform dynamics. Empirical relationships between the proportion of cohesive mud in the mixed sand-mud bed and the development rate and size of the bedforms are defined for future use in field and laboratory studies.

WOBBLE: A Proposed Mission to Characterize Past and Present Water on Mars

NASA Technical Reports Server (NTRS)

Udrea, Bogdan; Delory, Greg; Landis, Geoffrey; Duvet, Ludovic; Choudhuri, Ahsan; Prina, Mauro; Moreels, Pierre; Bedard, Donald; Furano, Gianluca

2002-01-01

WOBBLE ("Water Observations from a Balloon Borne Light Explorer") is a mission concept study for a small robotic probe to explore Mars and to accomplish a scientific mission compatible with the goals of the NASA Code S enterprise. The detection of past or present water is a crucial goal for Mars exploration, representing a cross-cutting science theme relevant to past or extant life, climate history, sample return missions and eventual human exploration. The WOBBLE mission concept was developed to study evidence of water using in-situ detection methods. The features on Mars most suited to this investigation are the gullies identified by Malin and Edgett as evidence for recent, near-surface runoff of liquid water. These features are typically located on the inside face of crater rims, where the local slope angle is at or near the angle of repose. This makes the terrain difficult or impossible to access with conventional wheeled rover technology. Combined with the small size of the gullies in relation to a standard landing error ellipse, scientific investigation of these features requires a new approach to surface mobility. WOBBLE uses a low-altitude balloon-borne platform to traverse the surface from the landing site, to the investigation site, and then rise up the slope to investigate the regions of interest at close range. Of the mobility technologies available for near-term Mars exploration, only a balloon platform is capable of a well targeted, detailed sampling of the gully regions over periods of days or more. The science approach embodied in WOBBLE is two-pronged, designed to investigate both the historical evidence of liquid water utilizing high-resolution geomorphology and the characterization of mineral deposits, and present subsurface liquid water using radar sounding techniques. The WOBBLE balloon is a high-pressure hydrogen gas design, 24 meters in diameter and lifting a total payload of 130 kg, including a high-resolution camera/IR imager, Raman spectrometer, and a ground penetrating radar (GPR) sounder. The stowed balloon and payload are designed to fit within the current airbag delivery system being built for the Mars Exploration Rovers. Characterization of local meteorological conditions and wind is made over the initial sols following landing and before balloon inflation. Following balloon inflation and launch, a controlled, targeted approach toward the identified regions of interest is made in a series of several low-altitude "hops," with the balloon tethered to the ground between the hop intervals. A "snake" system is used to control the altitude to a few tens of meters above the local ground level. Enroute to the target gully, GPR soundings and Raman spectroscopy measurements study past or present water, while continued camera bearings and meteorological measurements refine the next "hop" trajectory. Once at the gully/outflow region, GPR and Raman soundings continue while the camera obtains detailed, approx. 0.5 cm images for geomorphology studies. The WOBBLE concept is applicable to Mars Scout, Mars Surveyor, or Discovery class missions.

Legendary Mount Vesuvius is subject of intensive volcanological study

NASA Astrophysics Data System (ADS)

Spera, Frank

The Roman population centers of Pompeii and Herculaneum (circa 15,000 inhabitants) were destroyed when Mount Vesuvius erupted in 79 A.D. after centuries of repose. Many times since then its eruptions have claimed human lives; basaltic lava flows from an eruption in 1631 killed 3,000. Vesuvius' location, near the heart of the Roman empire—a center of learning in the ancient world—led it to become the site ofsome of the earliest volcanological studies on record.In letters to Tacitus, Pliny the Younger documented the sequence of events of the 79 A.D. plinian eruption. Geophysical studies of volcanoes were pioneered by Italian volcanologists who installed seismographs in an observatory on the flanks of Vesuvius to study volcano seismology and to forecast and monitor eruptions early this century. It is easy to understand why interest in Vesuvius has been so keen: it is accessible, persistently active, and a large population resides nearby. Today, around 1 million people live within the shadow of this potentially explosive and dangerous volcano.

Geomagnetic field excursion recorded 17 ka at Tianchi Volcano, China: New 40Ar/39Ar age and significance

NASA Astrophysics Data System (ADS)

Singer, Brad S.; Jicha, Brian R.; He, Huaiyu; Zhu, Rixiang

2014-04-01

New 40Ar/39Ar dating of a comenditic lava atop Tianchi Volcano, China, indicates eruption at 17.1 ± 0.9 ka. The flow interior records a pair of transitional virtual geomagnetic poles and a low paleointensity of ~25 μT. Thus, it records a geomagnetic field excursion that is younger than the 41 ka Laschamp or 32 ka Auckland excursions. Implications are: (1) following a repose of several tens of kyr, Tianchi Volcano became highly active immediately following termination of the last glaciation maximum. The flare-up of silicic eruptions may reflect rapid deglaciation of the edifice. (2) A 17 ka age for the Tianchi excursion provides the first direct radioisotopic evidence that excursional behavior, which is imprecisely dated and less well documented magnetically at several other sites, is a global feature of geodynamo behavior. (3) During the Brunhes chron, 13 well-dated excursions cluster into two periods, including seven between 17 and 212 ka, and six between about 530 and 730 ka.

The Role of Tectonic Stress in Triggering Large Silicic Caldera Eruptions

NASA Astrophysics Data System (ADS)

Cabaniss, Haley E.; Gregg, Patricia M.; Grosfils, Eric B.

2018-05-01

We utilize 3-D temperature-dependent viscoelastic finite element models to investigate the mechanical response of the host rock supporting large caldera-size magma reservoirs (volumes >102 km3) to local tectonic stresses. The mechanical stability of the host rock is used to determine the maximum predicted repose intervals and magma flux rates that systems may experience before successive eruption is triggered. Numerical results indicate that regional extension decreases the stability of the roof rock overlying a magma reservoir, thereby promoting early-onset caldera collapse. Alternatively, moderate amounts of compression (≤10 mm/year) on relatively short timescales (<104 years) increases roof rock stability. In addition to quantifying the affect of tectonic stresses on reservoir stability, our models indicate that the process of rejuvenation and mechanical failure is likely to take place over short time periods of hundreds to thousands of years. These findings support the short preeruption melt accumulation timescales indicated by U series disequilibrium studies.

Monitoring a supervolcano in repose: Heat and volatile flux at the yellostone caldera

USGS Publications Warehouse

Lowenstern, J. B.; Hurwitz, S.

2008-01-01

Although giant calderas ("supervolcanoes") may slumber for tens of thousands of years between eruptions, their abundant earthquakes and crustal deformation reveal the potential for future upheaval. Any eventual supereruption could devastate global human populations, so these systems must be carefully scrutinized. Insight into dormant but restless calderas can be gained by monitoring their output of heat and gas. At Yellowstone, the large thermal and CO2 fluxes require massive input of basaltic magma, which continues to invade the lower to mid-crust, sustains the overlying high-silica magma reservoir, and may result in volcanic hazard for millennia to come. The high flux of CO2 may contribute to the measured deformation of the caldera floor and can also modify the pressure, thermal, and chemical signals emitted from the magma. In order to recognize precursors to eruption, we must scrutinize the varied signals emerging from restless calderas with the goal of discriminating magmatic, hydrothermal, and hybrid phenomena.

Rapid differentiation in a sill-like magma reservoir: a case study from the campi flegrei caldera.

PubMed

Pappalardo, Lucia; Mastrolorenzo, Giuseppe

2012-01-01

In recent decades, geophysical investigations have detected wide magma reservoirs beneath quiescent calderas. However, the discovery of partially melted horizons inside the crust is not sufficient to put constraints on capability of reservoirs to supply cataclysmic eruptions, which strictly depends on the chemical-physical properties of magmas (composition, viscosity, gas content etc.), and thus on their differentiation histories. In this study, by using geochemical, isotopic and textural records of rocks erupted from the high-risk Campi Flegrei caldera, we show that the alkaline magmas have evolved toward a critical state of explosive behaviour over a time span shorter than the repose time of most volcanic systems and that these magmas have risen rapidly toward the surface. Moreover, similar results on the depth and timescale of magma storage were previously obtained for the neighbouring Somma-Vesuvius volcano. This consistency suggests that there might be a unique long-lived magma pool beneath the whole Neapolitan area.

Rapid differentiation in a sill-like magma reservoir: a case study from the campi flegrei caldera

PubMed Central

Pappalardo, Lucia; Mastrolorenzo, Giuseppe

2012-01-01

In recent decades, geophysical investigations have detected wide magma reservoirs beneath quiescent calderas. However, the discovery of partially melted horizons inside the crust is not sufficient to put constraints on capability of reservoirs to supply cataclysmic eruptions, which strictly depends on the chemical-physical properties of magmas (composition, viscosity, gas content etc.), and thus on their differentiation histories. In this study, by using geochemical, isotopic and textural records of rocks erupted from the high-risk Campi Flegrei caldera, we show that the alkaline magmas have evolved toward a critical state of explosive behaviour over a time span shorter than the repose time of most volcanic systems and that these magmas have risen rapidly toward the surface. Moreover, similar results on the depth and timescale of magma storage were previously obtained for the neighbouring Somma-Vesuvius volcano. This consistency suggests that there might be a unique long-lived magma pool beneath the whole Neapolitan area. PMID:23050096

Locating the depth of magma supply for volcanic eruptions, insights from Mt. Cameroon

PubMed Central

Geiger, Harri; Barker, Abigail K.; Troll, Valentin R.

2016-01-01

Mt. Cameroon is one of the most active volcanoes in Africa and poses a possible threat to about half a million people in the area, yet knowledge of the volcano’s underlying magma supply system is sparse. To characterize Mt. Cameroon’s magma plumbing system, we employed mineral-melt equilibrium thermobarometry on the products of the volcano’s two most recent eruptions of 1999 and 2000. Our results suggest pre-eruptive magma storage between 20 and 39 km beneath Mt. Cameroon, which corresponds to the Moho level and below. Additionally, the 1999 eruption products reveal several shallow magma pockets between 3 and 12 km depth, which are not detected in the 2000 lavas. This implies that small-volume magma batches actively migrate through the plumbing system during repose intervals. Evolving and migrating magma parcels potentially cause temporary unrest and short-lived explosive outbursts, and may be remobilized during major eruptions that are fed from sub-Moho magma reservoirs. PMID:27713494

Locating the depth of magma supply for volcanic eruptions, insights from Mt. Cameroon.

PubMed

Geiger, Harri; Barker, Abigail K; Troll, Valentin R

2016-10-07

Mt. Cameroon is one of the most active volcanoes in Africa and poses a possible threat to about half a million people in the area, yet knowledge of the volcano's underlying magma supply system is sparse. To characterize Mt. Cameroon's magma plumbing system, we employed mineral-melt equilibrium thermobarometry on the products of the volcano's two most recent eruptions of 1999 and 2000. Our results suggest pre-eruptive magma storage between 20 and 39 km beneath Mt. Cameroon, which corresponds to the Moho level and below. Additionally, the 1999 eruption products reveal several shallow magma pockets between 3 and 12 km depth, which are not detected in the 2000 lavas. This implies that small-volume magma batches actively migrate through the plumbing system during repose intervals. Evolving and migrating magma parcels potentially cause temporary unrest and short-lived explosive outbursts, and may be remobilized during major eruptions that are fed from sub-Moho magma reservoirs.

Peculiar Active-Tectonic Landscape Within the Sanctuary of Zeus at Mt. Lykaion (Peloponnese, Greece)

NASA Astrophysics Data System (ADS)

Davis, G. H.

2008-12-01

The Sanctuary of Zeus (Mt. Lykaion) lies in the Peloponnese within the Pindos fold and thrust belt. It is the object of investigation of the Mt. Lykaion Excavation and Survey (http://lykaionexcavation.org/). Mt. Lykaion is a thrust klippe, on the summit of which is an upper sanctuary marked by an ash altar, temenos, and column bases. Earliest objects recovered from the ash altar go back to 3000 BCE, leading Dr. David Romano (University of Pennsylvania), a principal leader of the project, to conclude that worship of divinities on the summit is ancient. Detailed structural geological mapping reveals one dimension of the "power" of the site. Crisscrossing the upper sanctuary are scree bands that mark the traces of active normal faults, which are expressions of tectonic stretching of the Aegean region. The scree bands, composed of cinder-block-sized limestone blocks, range up to 10 m in outcrop breadth, 100 m in length, and 5 m in thickness. Though discontinuous, most of the scree bands lie precisely on the traces of through-going faults, which cut and displace the sedimentary formations of the Pindos group. Some cut the thrust fault, whose elliptical trace defines the Lykaion klippe. What makes the scree bands of this active-tectonic landscape "peculiar" is that there are no cliffs from which the scree descends. Rather, the bands of scree occur along flanks of smooth, rounded hillslopes and ridges. The scree bands coincide with modest steps in the topography, ranging from tens of centimeters to several tens of meters. The specific bedrock formation where the bands are best developed is an Upper Cretaceous limestone whose average platy-bedding thickness (approximately 20 cm) matches closely the average joint spacing. The limestone has little mechanical integrity. It cannot support itself as a scarp footwall and instead collapses into a pile of scree, whose upper-surface inclination conforms to a stable angle of repose. Evidence of the contemporary nature of this faulting includes a scree band that nearly completely covers stone structures built by shepherds. Though the scree bands conceal surface ruptures, it is expected that trenching will determine that the scree cover may have preserved beneath it some expressions of surface rupture, and perhaps fault surfaces themselves.

Evolution of mud-capped dredge pits following excavation: sediment trapping and slope instability

NASA Astrophysics Data System (ADS)

Obelcz, J.; Xu, K.; Bentley, S. J.; Li, C.; Miner, M. D.; O'Connor, M. C.; Wang, J.

2016-02-01

Many fluvial channels incised the Northern Gulf of Mexico inner continental shelf during the late Quaternary. Mud-capped dredge pits (MCDPs), which are generally elongate and deep (8-10 m) excavations, target sandy fluvial channel deposits for coastal restoration projects. The morphological evolution of dredge excavations in noncohesive sandy substrate is well studied, but MCDPs have up to a several-meter-thick veneer of Holocene shelf mud overlying sandy channel deposits. This stratigraphy is hypothesized to result in more complex post-dredge morphology than pit walls simply slumping to the angle of repose shortly after excavation. Numerical modeling of MCDP post-dredge response conducted prior to excavation indicates pit walls may retrogressively fail, which is accounted for in pit design by assigning no-dredge setback buffers from pipelines or cultural and environmental resources. To validate model results and test effectiveness of setback buffers, a geophysical survey of the Sandy Point MCDP (20 km west of the Mississippi River Delta in 10m deep water), where 1.7 million m3 of sandy sediment was excavated in 2012, was conducted May 2015. A total of 84 line-km of high-resolution chirp subbottom and a 27 km2 grid of swath bathymetry and sidescan sonar were collected. The data indicate the dredge pit walls are differentially slumping, with the western pit wall in a more active state of failure than the eastern wall. The western failures morphologically resemble features observed along the muddy Mississippi River Delta Front at water depths of 20-100 m, including bowl-shaped collapse failures and retrogressive stair-stepped slumps; these failures may play a key role in evaluating the distance of setback buffer zone to pipelines. These features indicate the cohesive mud overlying the sandy infill has a prominent role in pit wall stability. A 0.5-1 m thick acoustically transparent package overlies the entire pit floor (interpreted as a possible fluid mud layer), overlying 1-3 m of post-dredge deposition that is concentrated along the western wall and center of the pit. The Sandy Point MCDP lies within a clockwise gyre, and its relief may serve as a significant trap of suspended sediment. These findings emphasize the role MCDPs play in sediment dynamics as well as their potential for submarine geohazards.

On the Internal Structure of Mobile Barchan Sand Dunes due to Granular Processes

NASA Astrophysics Data System (ADS)

Vriend, N. M.; Arran, M.; Louge, M. Y.; Hay, A. G.; Valance, A.

2017-12-01

In this work, we visualize the internal structure of mobile barchan desert dunes at the avalanche scale. We reveal an intriguing history of dune building using a novel combination of local sand sampling and advanced geophysical techniques resulting in high resolution measurements of individual avalanche events. Due to progressive rebuilding, granular avalanching, erosional and depositional processes, these marching barchan dunes are reworked every few years and a characteristic zebra-pattern (figure 1a), orientated parallel to the slipface at the angle of repose, appears at regular intervals. We present scientific data on the structure obtained from several mobile barchan dunes of different sizes during recent desert field campaigns (2014, 2015, 2017) in a mobile barchan dune field in Qatar (25.01°N, 51.34°E in the AlWakrah municipality). The site has been equipped with a weather station and has been regularly visited by a multidisciplinary research team in recent years (e.g. [1]). By applying high-frequency (1200 MHz) ground penetrating radar (GPR) transects across the midline (figure 1b) we map the continuous evolution of this cross-bedding at high resolution deep within the dune. The GPR reveals a slope reduction of the slipface near the base of the dune; evidence of irregular wind reversals; and the presence of a harder aeolian cap around the crest and extending to the brink. The data is supplemented with granulometry from layers stabilized by dyed water injection and uncovered by excavating vertical walls perpendicular to old buried avalanches. We attribute visible differences in water penetration between adjacent layers to fine particle segregation processes in granular avalanches. This work was made possible by the support of NPRP grant 6-059-2-023 from the Qatar National Research Fund to MYL and AGH, and a Royal Society Dorothy Hodgkin Research Fellowship to NMV. We thank Jean-Luc Métayer for performing detailed particle size distribution measurements. References: [1] Louge, M. Y., A. Valance, A. Ould el-Moctar, J. Xu, A. G. Hay, and R. Richer, Temperature and humidity within a mobile barchan sand dune, implications for microbial survival, J. Geophys. Res. 118, doi:10.1002/2013JF002839 (2013).

The onset of the volcanism in the Ciomadul Volcanic Dome Complex (Eastern Carpathians): Eruption chronology and magma type variation

NASA Astrophysics Data System (ADS)

Molnár, Kata; Harangi, Szabolcs; Lukács, Réka; Dunkl, István; Schmitt, Axel K.; Kiss, Balázs; Garamhegyi, Tamás; Seghedi, Ioan

2018-04-01

Combined zircon U-Th-Pb and (U-Th)/He dating was applied to refine the eruption chronology of the last 2 Myr for the andesitic and dacitic Pilişca volcano and Ciomadul Volcanic Dome Complex (CVDC), the youngest volcanic area of the Carpathian-Pannonian region, located in the southernmost Harghita, eastern-central Europe. The proposed eruption ages, which are supported also by the youngest zircon crystallization ages, are much younger than the previously determined K/Ar ages. By dating every known eruption center in the CVDC, repose times between eruptive events were also accurately determined. Eruption of the andesite at Murgul Mare (1865 ± 87 ka) and dacite of the Pilişca volcanic complex (1640 ± 37 ka) terminated an earlier pulse of volcanic activity within the southernmost Harghita region, west of the Olt valley. This was followed by the onset of the volcanism in the CVDC, which occurred after several 100s kyr of eruptive quiescence. At ca. 1 Ma a significant change in the composition of erupted magma occurred from medium-K calc-alkaline compositions to high-K dacitic (Baba-Laposa dome at 942 ± 65 ka) and shoshonitic magmas (Malnaş and Bixad domes; 964 ± 46 ka and 907 ± 66 ka, respectively). Noteworthy, eruptions of magmas with distinct chemical compositions occurred within a restricted area, a few km from one another. These oldest lava domes of the CVDC form a NNE-SSW striking tectonic lineament along the Olt valley. Following a brief (ca. 100 kyr) hiatus, extrusion of high-K andesitic magma continued at Dealul Mare (842 ± 53 ka). After another ca. 200 kyr period of quiescence two high-K dacitic lava domes extruded (Puturosul: 642 ± 44 ka and Balvanyos: 583 ± 30 ka). The Turnul Apor lava extrusion occurred after a ca. 200 kyr repose time (at 344 ± 33 ka), whereas formation of the Haramul Mic lava dome (154 ± 16 ka) represents the onset of the development of the prominent Ciomadul volcano. The accurate determination of eruption dates shows that the volcanic eruptions were often separated by prolonged (ca. 100 to 200 kyr) quiescence periods. Demonstration of recurrence of volcanism even after such long dormancy has to be considered in assessing volcanic hazards, particularly in seemingly inactive volcanic areas, where no Holocene eruptions occurred. The term of 'volcanoes with Potentially Active Magma Storage' illustrates the potential of volcanic rejuvenation for such long-dormant volcanoes with the existence of melt-bearing crustal magma body.

Autre cause de mort subite du nourrisson: à propos d'un cas clinique de syndrome du QT long congenital

PubMed Central

Seka, Zena; Mols, Pierre; Gobin, Eric; Ngatchou, William

2014-01-01

Le syndrome du QT long congénital est une maladie rythmique liée à une mutation génétique et caractérisée par un espace QT allongé sur l’électrocardiogramme, des arythmies malignes type torsade de pointe et fibrillation ventriculaire entraînant une mort subite. Les gènes impliqués dans ces mutations codent pour des sous unités des canaux ioniques responsables de l'activité électrique cardiaque. Le diagnostic est basé sur l’électrocardiogramme, une enquête familiale et l’étude génétique. Le traitement repose sur les bêtabloquants, la sympathectomie et le stimulateur cardiaque. Nous rapportons le cas d'un nourrisson de 2 ans retrouvé en état de mort apparente. Nous discutons de sa prise en charge initiale, de l'enquête familiale et de son suivi ultérieur. PMID:25667708

Mécanismes et traitement de l’anémie aiguë chez le brûlé grave

PubMed Central

Siah, S.; El Khatib, K.; Messaoudi, N.

2016-01-01

Summary Les brûlés graves présentent souvent, au cours de la phase aiguë, des anémies plus au moins profondes pouvant nécessiter des transfusions. L’anémie du brûlé a deux origines principales: le saignement péri-opératoire (des stratégies doivent être mises en place pour le réduire) et l’anémie de réanimation (que l’on peut en partie réduire en évitant les bilans inutiles) chez un patient ayant des troubles de l’hématopoïèse. Le traitement, chez ces patients à l’hématopoïèse altérée, repose sur la transfusion. Celle-ci n’est pas dénuée d’effets secondaires et une stratégie transfusionnelle restrictive doit être appliquée. PMID:28149231

Insulinome de haut grade découvert après 5 ans d’hypoglycémies graves

PubMed Central

Anoun, Nadia; Hasnaoui, Hamza; Hassani, Firdaous Ameziane; Idrissi, Mehdi Bourakkadi; Ousadden, Abdelmalek; Ouahabi, Hanan El; Taleb, Khalid Ait

2017-01-01

Les tumeurs endocrines fonctionnelles du pancréas sont des lésions rares, parmi lesquelles les insulinomes sont les plus fréquents. La majorité des patients atteints d'insulinome ont entre 30 et 60 ans et 59% d'entre eux sont des femmes. La plupart des insulinomes sont sporadiques, alors que 10% sont développés chez des patients atteints de NEM. Le diagnostic repose sur la clinique et sur le bilan biologique. Le bilan d'imagerie préopératoire (Echo-endoscopie, TDM, IRM) est essentiel localisant la tumeur dans plus de 80% des cas. Le traitement de référence est l'exérèse chirurgicale de la tumeur. Nous rapportons ici un cas d'insulinome de haut grade développé sur la face antérieure de la queue du pancréas chez une patiente de 50 ans. PMID:28979651

Sheet Flows, Avalanches, and Dune Evolution on Earth and Mars

NASA Technical Reports Server (NTRS)

2003-01-01

This investigation is a collaboration between researchers at Cornell University, the University of Florida, and the University of Rennes 1, France. Flow modeling at Cornell University focused on mechanisms for the suspension and transport of wind-blown sand that are important in both terrestrial and Martian environments. These mechanisms include the saltation (or jumping) of grains, collisions between grains, and the interaction of grains with the velocity fluctuations of the turbulent wind. Of particular interest are sheet flows; these are relatively thin, highly concentrated regions of grains flowing near the ground under the influence of a strong turbulent wind. In them, the grains are suspended by interparticle collisions. Sheet flows may be relatively rare events, but they have the capacity to move great amounts of sand. In order to describe sheet flows, a turbulent mixture theory was formulated for particles in a fluid in which fluctuations in the volume fiaction of the particles take place on the scale of the turbulent eddies. Ensemble averaged equations for particle and fluid mass, momentum, and energy and fluid rate of dissipation were expressed in terms of Farve (concentration) averaged velocities and the associated velocity fluctuations. Correlations that describe the turbulent suspension of particles and dissipation of turbulent energy of both phases due to fluid particle interactions were modeled and boundary conditions at the bed and at the upper surface of the collisional flow were formulated. The boundary conditions at the upper surface were tested in a numerical simulation developed at the University of Florida. Steady and unsteady solutions for steady and unsteady fully-developed flows were obtained over a range of wind speeds fiom the lowest for which collisional between particles occurred to at which turbulent suspension is found to dominate collisional suspension. Below the value of the wind speed at which collisions between particles were unimportant, numerical solutions were obtained for the velocity distribution function and the resulting fields of concentration, particle and gas mean velocity, and particle shear stress for the steady two-dimensional saltation of spherical sand particles driven by a turbulent wind over a bed characterized by a simple relationship (the splash function) between the properties of incoming particles and those of the rebounding particles and other particles ejected fiom the bed. At the University of Rennes 1, experiments devoted to the characterization of the splash function for beds consisting of either random or ordered arrays of spheres in two- dimensions were completed. These indicated the role played by the packing geometry in the rebound and ejection of grains. Preliminary experiments on response of a three- dimensional collision bed to a collision with a single particle were performed. Data was taken with a single camera focused on the plane of collision. Here, for example, the decrease of the effective coefficient of restitution of the bed with an increase of the angle of incidence of the incoming particle has been measured. Other experiments on avalanches at Rennes studied the properties of the flows of particles that are responsible for the motion of the leeward side of a dune. In these, the dependence of the initiation of avalanches on the packing and depth of the particles was measured. Particle migration was studied in inclined flows of a binary mixture of disks and the mechanisms of diffision and segregation were isolated and characterized. The influence of side wall on dense, rapid inclined flows was measured and shown to be the reason why the angle of the free surface in such flows can exceed the static angle of repose. Future research will be devoted to a better understanding the transition between saltating (collisionless) and collisional flows as the wind speed the increases. This will involve the understanding of the evolution of the splash function as clisions with the bed become more numerous, more frequent, and more violent.

Observations of the eruptions of July 22 and August 7, 1980, at Mount St. Helens, Washington

USGS Publications Warehouse

Hoblitt, Richard P.

1986-01-01

The explosive eruptions of July 22 and August 7, 1980, at Mount St. Helens, Wash., both included multiple eruptive pulses. The beginnings of three of the pulses-two on July 22 and one on August 7-were witnessed and photographed. Each of these three began with a fountain of gases and pyroclasts that collapsed around the vent and generated a pyroclastic density flow. Significant vertical-eruption columns developed only after the density flows were generated. This behavior is attributable to either an increase in the gas content of the eruption jet or a decrease in vent radius with time. An increase in the gas content may have occurred as the vent was cleared (by expulsion of a plug of pyroclasts) or as the eruption began to tap deeper, gas-rich magma after first expelling the upper, gas-depleted part of the magma body. An effective decrease of the vent radius with time may have occurred as the eruption originated from progressively deeper levels in the vent. All of these processes-vent clearing; tapping of deeper, gas-rich magma; and effective decrease in vent radius-probably operated to some extent. A 'relief-valve' mechanism is proposed here to account for the occurrence of multiple eruptive pulses. This mechanism requires that the conduit above the magma body be filled with a bed of pyroclasts, and that the vesiculation rate in the magma body be inadequate to sustain continuous eruption. During a repose interval, vesiculation of the magma body would cause gas to flow upward through the bed of pyroclasts. If the rate at which the magma produced gas exceeded the rate at which gas escaped to the atmosphere, the vertical pressure difference across the bed of pyroclastic debris would increase, as would the gas-flow rate. Eventually a gas-flow rate would be achieved that would suddenly diminish the ability of the bed to maintain a pressure difference between the magma body and the atmosphere. The bed of pyroclasts would then be expelled (that is, the relief valve would open) and an eruption would commence. During the eruption, gas would be lost faster than it could be replaced by vesiculation, so the gas-flow rate in the conduit would decrease. Eventually the gas-flow rate would decrease to a value that would be inadequate to expel pyroclasts, so the conduit would again become choked with pyroclasts (that is, the relief valve would close). Another period of repose would commence. The eruption/repose sequence would be repeated until gas-production rates were inadequate to reopen the valve, either because the depth of the pyroclast bed had become too great, the volatile content of the magma had become too low, or the magma had been expended. A timed sequence of photographs of a pyroclastic density flow on August 7 indicates that, in general, the velocity of the flow front was determined by the underlying topography. Observations and details of the velocity/topography relationship suggest that both pyroclastic flows and pyroclastic surges formed. The following mechanism is consistent with the data. During initial fountain collapse and when the flow passed over steep, irregular terrain, a highly inflated suspension of gases and pyroclasts formed. In this suspension, the pyroclasts underwent rapid differential settling according to size and density; a relatively low-concentration, fine-grained upper phase formed over a relatively high-concentration coarse-grained phase. The low-particle-concentration phase (the pyroclastic surge) was subject to lower internal friction than the basal high-concentration phase (the pyroclastic flow), and so accelerated away from it. The surge advanced until it had deposited so much of its solid fraction that its net density became less than that of the ambient air. At this point it rose convectively off the ground, quickly decelerated, and was overtaken by the pyroclastic flow. The behavior of the flow of August 7 suggests that a pyroclastic density flow probably expands through the ingestion of ai

An overview of medical malpractice litigation and the perceived crisis.

PubMed

Litvin, S Gerald

2005-04-01

In this overview of medical malpractice litigation in the United States, practical and philosophic aspects of the so-called malpractice litigation crisis are addressed. After reviewing the historical, legal rationale for compensating victims of negligent conduct by others, attention is focused on the plight of physicians who are charged with medical negligence and the oppressive insurance premiums that impose a heavy burden on all health care providers, particularly those in the surgical fields. A variety of political solutions advanced to "correct" the problem is reviewed. A historical prospective of malpractice litigation in the United States is presented together with an analysis of various legislative proposals--many of which have already been enacted in various states that will ostensibly "cure" the problems that concern clinicians. Consideration of the various legislative proposals includes: arbitrary limits on pain and suffering awards (caps); elimination of joint and several liability; regulation of attorneys fees; elimination of the collateral source rule; abrogation of punitive damages; proposals for periodic payments; and statutes of repose. Various procedural changes in the processing of malpractice claims are reviewed and analyzed from the perspective of both fairness and efficacy.

[Water immersion as an anti-g protection for pilot. Pro et contra].

PubMed

Barer, A S

2007-01-01

In the period of 1988 - 1990 the ZVEZDA Aerospace medicine Department fulfilled comprehensive physiological investigations in order to assess the prospects for water immersion as an anti-g gear for pilots of high-maneuver aircraft. Both dry and open water immersion methods were used. More than 150 centrifuge runs were conducted to define limits for the acceleration value and time of 9-g tolerance. Volunteered subjects in the pilot's posture were inclined at 35 degrees and 55 degrees to the total inertial force vector. The obvious subjective discomfort felt during acceleration and absence of clinical aftereffect were qualified as a positive outcome. The subjects were ready for repeated runs even after a very brief repose. The main impediment to the professional anti-g use of immersion is visual disorders which in this case are not predictors of coming loss of consciousness and attributed to alterations in regional hemodynamics. The authors assert that there is a good reason to continue search for implementation of the immersion principle in g-protection of pilots to reduce the rate of professional pathologies and to intensify flights.

Adolescents, Graduated Autonomy, and Genetic Testing

PubMed Central

Fox, Susan

2012-01-01

Autonomy takes many shapes. The concept of “graduated autonomy” is conceived as comprising several unique features: (1) it is incremental, (2) it is proportional, and (3) it is related to the telos of the life stage during which it occurs. This paper focuses on graduated autonomy in the context of genetic testing during adolescence. Questions can be raised about other life stages as well, and some of these questions will be addressed by discussing a possible fourth characteristic of graduated autonomy, that is, its elasticity. Further scholarship and analysis is needed to refine the concept of graduated autonomy and examine its applications. “There is no steady. . . progress in this life; we do not advance through fixed gradations, and at the last one pause through infancy’s unconscious spell, boyhood’s thoughtless faith, adolescence’ doubt (the common doom), then skepticism, then disbelief, resting at last in manhood’s pondering repose of If. But once gone through, we trace the round again; and are infants, boys, and men, and Ifs eternally. Where lies the final harbor, whence we unmoor no more?” Herman Melville PMID:22567406

Adolescents, graduated autonomy, and genetic testing.

PubMed

Fox, Susan

2012-01-01

Autonomy takes many shapes. The concept of "graduated autonomy" is conceived as comprising several unique features: (1) it is incremental, (2) it is proportional, and (3) it is related to the telos of the life stage during which it occurs. This paper focuses on graduated autonomy in the context of genetic testing during adolescence. Questions can be raised about other life stages as well, and some of these questions will be addressed by discussing a possible fourth characteristic of graduated autonomy, that is, its elasticity. Further scholarship and analysis is needed to refine the concept of graduated autonomy and examine its applications."There is no steady. . . progress in this life; we do not advance through fixed gradations, and at the last one pause through infancy's unconscious spell, boyhood's thoughtless faith, adolescence' doubt (the common doom), then skepticism, then disbelief, resting at last in manhood's pondering repose of If. But once gone through, we trace the round again; and are infants, boys, and men, and Ifs eternally. Where lies the final harbor, whence we unmoor no more?"Herman Melville.

Radiocardiographic measurement of minimum central transit times by means of indium-113m-DTPA and of a 8-crystal radiocardiograph (Gamma Retina VI). Comparative investigations on non-trained and athletics in repose and after stress (in German)

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

Knapp, W.H.

The minimum cardiac transit times (MTT's) at rest and following sub- maximum stresses were measured in 97 individual examinations of untrained persons and high performance athletes. It turned out that there is a strong dependence on cardiac frequency of the MTT's. This relation can be described quite satisfactorily by a hyperbolic function and in this way allows a frequency correction to be made of the MTT's. The MTT's standardized in this way (MTT.f values) represent the quotient of the end diastolic segment volume/beat volume. In the whole lesser circulatory system almost identical MTT.f values were found for the two groupsmore » under comparison at rest and following stress. In the ventricles, however, and especially so in the left ventricle, the MTT.f values were clearly higher with athletes than with untrained persons, but they strongly decreased after stresses, while the respective values remained almost constant in ordinary persons. (orig./RF)« less

Temporal variations in volumetric magma eruption rates of Quaternary volcanoes in Japan

NASA Astrophysics Data System (ADS)

Yamamoto, Takahiro; Kudo, Takashi; Isizuka, Osamu

2018-04-01

Long-term evaluations of hazard and risk related to volcanoes rely on extrapolations from volcano histories, including the uniformity of their eruption rates. We calculated volumetric magma eruption rates, compiled from quantitative eruption histories of 29 Japanese Quaternary volcanoes, and analyzed them with respect to durations spanning 101-105 years. Calculated eruption rates vary greatly (101-10-4 km3 dense-rock equivalent/1000 years) between individual volcanoes. Although large basaltic stratovolcanoes tend to have high eruption rates and relatively constant repose intervals, these cases are not representative of the various types of volcanoes in Japan. At many Japanese volcanoes, eruption rates are not constant through time, but increase, decrease, or fluctuate. Therefore, it is important to predict whether eruption rates will increase or decrease for long-term risk assessment. Several temporal co-variations of eruption rate and magmatic evolution suggest that there are connections between them. In some cases, magma supply rates increased in response to changing magma-generation processes. On the other hand, stable plumbing systems without marked changes in magma composition show decreasing eruption rates through time.[Figure not available: see fulltext.

Volcanic alert system (VAS) developed during the 2011-2014 El Hierro (Canary Islands) volcanic process

NASA Astrophysics Data System (ADS)

García, Alicia; Berrocoso, Manuel; Marrero, José M.; Fernández-Ros, Alberto; Prates, Gonçalo; De la Cruz-Reyna, Servando; Ortiz, Ramón

2014-06-01

The 2011 volcanic unrest at El Hierro Island illustrated the need for a Volcanic Alert System (VAS) specifically designed for the management of volcanic crises developing after long repose periods. The VAS comprises the monitoring network, the software tools for analysis of the monitoring parameters, the Volcanic Activity Level (VAL) management, and the assessment of hazard. The VAS presented here focuses on phenomena related to moderate eruptions, and on potentially destructive volcano-tectonic earthquakes and landslides. We introduce a set of new data analysis tools, aimed to detect data trend changes, as well as spurious signals related to instrumental failure. When data-trend changes and/or malfunctions are detected, a watchdog is triggered, issuing a watch-out warning (WOW) to the Monitoring Scientific Team (MST). The changes in data patterns are then translated by the MST into a VAL that is easy to use and understand by scientists, technicians, and decision-makers. Although the VAS was designed specifically for the unrest episodes at El Hierro, the methodologies may prove useful at other volcanic systems.

Scrubbing masks magmatic degassing during repose at Cascade-Range and Aleutian-Arc volcanoes

USGS Publications Warehouse

Symonds, Robert B.; Janik, C.J.; Evans, William C.; Ritchie, B.E.; Counce, Dale; Poreda, R.J.; Iven, Mark

2003-01-01

Between 1992 and 1998, we sampled gas discharges from ≤173°C fumaroles and springs at 12 quiescent but potentially restless volcanoes in the Cascade Range and Aleutian Arc (CRAA) including Mount Shasta, Mount Hood, Mount St. Helens, Mount Rainier, Mount Baker, Augustine Volcano, Mount Griggs, Trident, Mount Mageik, Aniakchak Crater, Akutan, and Makushin. For each site, we collected and analyzed samples to characterize the chemical (H2O, CO2, H2S, N2, CH4, H2, HCl, HF, NH3, Ar, O2, He) and isotopic (δ13C of CO2, 3He/4He, 40Ar/36Ar, δ34S, δ13C of CH4, δ15N, and δD and δ18O of water) compositions of the gas discharges, and to create baseline data for comparison during future unrest. The chemical and isotopic data show that these gases contain a magmatic component that is heavily modified from scrubbing by deep hydrothermal (150° - 350°C) water (primary scrubbing) and shallow meteoric water (secondary scrubbing). The impact of scrubbing is most pronounced in gas discharges from bubbling springs; gases from boiling-point fumaroles and superheated vents show progressively less impact from scrubbing. The most effective strategies for detecting gas precursors to future CRAA eruptions are to measure periodically the emission rates of CO2 and SO2, which have low and high respective solubilities in water, and to monitor continuously CO2 concentrations in soils around volcanic vents. Timely resampling of fumaroles can augment the geochemical surveillance program by watching for chemical changes associated with drying of fumarolic pathways (all CRAA sites), increases in gas geothermometry temperatures (Mount Mageik, Trident, Mount Baker, Mount Shasta), changes in δ13C of CO2 affiliated with magma movement (all CRAA site), and increases in 3He/4He coupled with intrusion of new magma (Mount Rainier, Augustine Volcano, Makushin, Mount Shasta). Repose magmatic degassing may discharge substantial amounts of S and Cl into the edifices of Mount Baker and several other CRAA volcanoes that is trapped by primary and secondary scrubbing. The consequent acidic fluids produce ongoing alteration in the 0.2- to 3-km-deep hydrothermal systems and in fields of boiling-point fumaroles near the surface. Such alteration may influence edifice stability and contribute to the formation of more-hazardous cohesive debris flows. In particular, we recommend further investigation of the volume, extent, and hazards of hydrothermal alteration at Mount Baker. Other potential hazards associated with the CRAA volcano hydrothermal systems include hydrothermal eruptions and, for deeper systems intruded by magma, deep-seated edifice collapse.

Dueling Volcanoes: How Activity Levels At Kilauea Influence Eruptions At Mauna Loa

NASA Astrophysics Data System (ADS)

Trusdell, F.

2011-12-01

The eruption of Kilauea at Pu`u `O`o is approaching its 29th anniversary. During this time, Mauna Loa has slowly inflated following its most recent eruption in 1984. This is Mauna Loa's longest inter-eruptive interval observed in HVO's 100 years of operation. When will the next eruption of Mauna Loa take place? Is the next eruption of Mauna Loa tied to the current activity at Kilauea? Historically, eruptive periods at Kilauea and Mauna Loa volcanoes appear to be inversely correlated. In the past, when Mauna Loa was exceptionally active, Kilauea Volcano was in repose, recovery, or in sustained lava lake activity. Swanson and co-workers (this meeting) have noted that explosive activity on Kilauea, albeit sporadic, was interspersed between episodes of effusive activity. Specifically, Swanson and co-workers note as explosive the time periods between 300 B.C.E.-1000 C.E and 1500-1800 C.E. They also point to evidence for low magma supply to Kilauea during these periods and few flank eruptions. During the former explosive period, Mauna Loa was exceedingly active, covering approximately 37% of its surface or 1882 km2, an area larger than Kilauea. This period is also marked by summit activity at Mauna Loa sustained for 300 years. In the 1500-1800 C.E. period, Mauna Loa was conspicuously active with 29 eruptions covering an area of 446 km2. In the late 19th and early 20th century, Kilauea was dominated by nearly continuous lava-lake activity. Meanwhile Mauna Loa was frequently active from 1843 C.E. to 1919 C.E., with 24 eruptions for an average repose time of 3.5 years. I propose that eruptive activity at one volcano may affect eruptions at the other, due to factors that impact magma supply, volcanic plumbing, and flank motion. This hypothesis is predicated on the notion that when the rift zones of Kilauea, and in turn its mobile south flank, are active, Mauna Loa's tendency to erupt is diminished. Kilauea's rift zones help drive the south flank seaward, in turn, as Mauna Loa inflates its flank is not buttressed on the southeast. Consequently, asymmetrical spreading occurs resulting in dilation of the shallow magma storage centers, which ultimately culminates in decreased magma pressure and therefore lessened ability to erupt. Whether or not this hypothesis is accurate, there is growing geologic evidence for inverse activity levels at both volcanoes. This hypothesis is readily testable and can have profound implications on how we monitor shield volcanoes, which impacts our ability to forecast eruptions, conduct hazard assessments, and risk analysis.

Degassing during quiescence as a trigger of magma ascent and volcanic eruptions.

PubMed

Girona, Társilo; Costa, Fidel; Schubert, Gerald

2015-12-15

Understanding the mechanisms that control the start-up of volcanic unrest is crucial to improve the forecasting of eruptions at active volcanoes. Among the most active volcanoes in the world are the so-called persistently degassing ones (e.g., Etna, Italy; Merapi, Indonesia), which emit massive amounts of gas during quiescence (several kilotonnes per day) and erupt every few months or years. The hyperactivity of these volcanoes results from frequent pressurizations of the shallow magma plumbing system, which in most cases are thought to occur by the ascent of magma from deep to shallow reservoirs. However, the driving force that causes magma ascent from depth remains unknown. Here we demonstrate that magma ascent can be triggered by the passive release of gas during quiescence, which induces the opening of pathways connecting deep and shallow magma reservoirs. This top-down mechanism for volcanic eruptions contrasts with the more common bottom-up mechanisms in which magma ascent is only driven by processes occurring at depth. A cause-effect relationship between passive degassing and magma ascent can explain the fact that repose times are typically much longer than unrest times preceding eruptions, and may account for the so frequent unrest episodes of persistently degassing volcanoes.

Influence of Exsolved Volatiles on Reheating Silicic Magmas by Recharge and Consequences for Eruptive Style at Volcán Quizapu (Chile)

NASA Astrophysics Data System (ADS)

Degruyter, W.; Huber, C.; Bachmann, O.; Cooper, K. M.; Kent, A. J. R.

2017-11-01

The two most recent eruptions of Volcán Quizapu (southern Andes, Chile), only 85 years apart, were both triggered by magma recharge and extruded the same volume (about 5 km3) of the same volatile-rich dacitic magma, but showed a remarkable shift from effusive (1846-1847) to explosive (1932) behavior. We demonstrate, using a newly developed model, that the presence or absence of an exsolved volatile phase in the reservoir strongly influences its mechanical and thermal response to new inputs of magma. We propose that, prior to the 1846-1847 effusive eruption, gas bubbles damped the build-up of excess pressure and allowed recharge of a significant volume of magma before triggering the 1846-1847 eruption. The strong temperature increase that resulted enhanced syneruptive outgassing leading to an effusive eruption. In contrast, during the repose period between the 1847 and 1932 eruptions, new recharges found a much less compressible host reservoir as the exsolved gas phase was largely removed in response to the prior eruption, yielding rapid pressurization, minor reheating, and comparatively less syneruptive outgassing. The combination of these effects culminated in an explosive eruption.

Immunohistochemical and ultrastructural evidence of functional organization along the Corydoras paleatus intestine.

PubMed

Plaul, Silvia E; Pastor, Raquel; Díaz, Alcira O; Barbeito, Claudio G

2016-03-01

The Neotropical catfish, Corydoras paleatus (Callichthyidae) is a facultative air-breathing teleost that makes use of the caudal portion of the intestine as an accessory air-breathing organ. This portion is highly modified, being well vascularized with capillaries between epithelial cells, which makes it well suited for gas exchange. Instead, the cranial portion is a digestion and absorption site, as it has a typical intestinal epithelium with columnar cells arranged in a single row, villi and less vascularized tunica mucosa. Therefore, the intestine was studied by light and electron microscopy to assess differences between the cranial, middle and caudal portions. To characterize the potential for cell proliferation of this organ, we used anti-proliferating cell nuclear antigen antibody and anti-Na(+) K(+) -ATPase monoclonal antibody to detect the presence of Na(+) /K(+) pump. In C. paleatus it was observed that cell dynamics showed a decreasing gradient of proliferation in cranio-caudal direction. Also, the intestine of this catfish is an important organ in ionoregulation: the basolateral Na(+) /K(+) pump may have an active role, transporting Na(+) out of the cell while helping to maintain the repose potential and to regulate cellular volume. © 2016 Wiley Periodicals, Inc.

Incorporating the eruptive history in a stochastic model for volcanic eruptions

NASA Astrophysics Data System (ADS)

Bebbington, Mark

2008-08-01

We show how a stochastic version of a general load-and-discharge model for volcanic eruptions can be implemented. The model tracks the history of the volcano through a quantity proportional to stored magma volume. Thus large eruptions can influence the activity rate for a considerable time following, rather than only the next repose as in the time-predictable model. The model can be fitted to data using point-process methods. Applied to flank eruptions of Mount Etna, it exhibits possible long-term quasi-cyclic behavior, and to Mauna Loa, a long-term decrease in activity. An extension to multiple interacting sources is outlined, which may be different eruption styles or locations, or different volcanoes. This can be used to identify an 'average interaction' between the sources. We find significant evidence that summit eruptions of Mount Etna are dependent on preceding flank eruptions, with both flank and summit eruptions being triggered by the other type. Fitted to Mauna Loa and Kilauea, the model had a marginally significant relationship between eruptions of Mauna Loa and Kilauea, consistent with the invasion of the latter's plumbing system by magma from the former.

Maladie de Kaposi à localisation broncho-pulmonaire révélant une infection VIH

PubMed Central

Sebbar, Amal; Zaghba, Nahid; Benjelloun, Hanane; Bakhatar, Abdelaziz; Yassine, Najiba

2015-01-01

La maladie de Kaposi (MK) associée au VIH, forme dite épidémique, a été décrite la 1ère fois en 1981 par Hymmes. C'est l'affection maligne la plus fréquente au cours du SIDA. La MK est à l'origine de 10% des atteintes pleuropulmonaires au cours de l'infection par le VIH et 40% des pneumopathies en cas de MK cutanéomuqueuse. Les localisations pulmonaires occupent la deuxième place des atteintes viscérales après la forme digestive. Le diagnostic repose sur des arguments épidémiologiques, cliniques, radiologiques, biologiques, endoscopiques et histologiques. Nous rapportons un cas de MK broncho-pulmonaire compliquant une infection VIH chez un patient présentant une maladie de Kaposi cutanée de découverte fortuite au cours de l'atteinte pulmonaire. Le diagnostic a été retenu après avoir éliminé les maladies opportunistes à tropisme pulmonaire. Le Kaposi pulmonaire constitue l'atteinte la plus grave de la MK-sida et la survie après le diagnostic est courte malgré les thérapeutiques agressives. PMID:26958142

Localisation buccale d’un lymphome de Burkitt: à propos d’un cas

PubMed Central

Kissi, Lamia; El Bouihi, Rajaa; Lamchahab, Mouna; Alaoui, Ahmed; Benyahya, Ihsane

2017-01-01

Le lymphome de Burkitt (LB) est une forme de lymphome malin non-Hodgkinien qui provient de l'évolution maligne et de la prolifération de cellules lymphoïdes de type B. Le diagnostic positif repose sur la biopsie d'une masse tumorale ou la ponction de la moelle osseuse révélant la présence de cellules tumorales. Le cas rapporté est celui d'un jeune homme d'une vingtaine d'années qui a été adressé pour des tuméfactions gingivales évoluant depuis 1 mois suite à des extractions dentaires. L'examen anatomopathologique après biopsie complété par l'immunohistochimie conclut à un lymphome de Burkitt. La prise en charge a consisté en une chimiothérapie. Bien que rare, le lymphome de Burkitt est une tumeur agressive qui représente un véritable problème de santé publique d'où la place importante qu'occupe le médecin dentiste dans le diagnostic précoce afin de permettre une prise en charge rapide et appropriée seule garante de la guérison. PMID:28451040

Investigation of drug-excipient compatibility using rheological and thermal tools

NASA Astrophysics Data System (ADS)

Trivedi, Maitri R.

HYPOTHESIS: We plan to investigate a different approach to evaluate drug-excipient physical compatibility using rheological and thermal tools as opposed to commonly used chemical techniques in pharmaceutical industry. This approach offers practical solutions to routinely associated problems arising with API's and commonly used hydrates forms of excipients. ABSTRACT: Drug-Excipient compatibility studies are an important aspect of pre-formulation and formulation development in pharmaceutical research and development. Various approaches have been used in pharmaceutical industry including use of thermal analysis and quantitative assessment of drug-excipient mixtures after keeping the samples under stress environment depending upon the type of formulation. In an attempt to provide better understanding of such compatibility aspect of excipients with different properties of API, various rheological and thermal studies were conducted on binary mixtures of excipients which exist in different hydrates. Dibasic Calcium Phosphate (DCP, anhydrous and dihydrate forms) and Lactose (Lac, anhydrous and monohydrate) were selected with cohesive API's (Acetaminophen and Aspirin). Binary mixtures of DCP and Lac were prepared by addition of 0% w/w to 50% w/w of the API into each powder blend. Rheological and thermal aspects were considered using different approaches such as powder rheometer, rotational shear cell and traditional rheometery approaches like angle of repose (AOR), hausner's ratio (HR) and cares index (CI). Thermal analysis was conducted using modulated differential scanning calorimetry (MDSC) and thermal effusivity. The data suggested that the powder rheometer showed distinctive understanding in the flowability behavior of binary mixtures with addition of increasing proportion of API's than traditional approaches. Thermal approaches revealed the potential interaction of water of crystallization DCP-D with the API (APAP) while such interactions were absent in DCP-A, while in case of Lac-M and Lac-A, interaction with water of crystallization were not present. Binary mixtures prepared with DCP-D were better flowable while blends with DCP-A were better in stability (physical), compressibility and permeability. Similarly binary mixtures prepared with Lac-M were better flowable and stable in physical compatibility as compared to Lac-A. Lac-A were better in compressibility and permeability. Second part of these research included understanding the powder behavior from wet granulation point of view. Wet granulation includes the formation of agglomerates with powders to form granules in order to have better flowability, content uniformity and compressibility of granular mass. End point determination of powders involving change in powder energies and compressibility, permeability along with thermal analyses were conducted. The effects of water of crystallization on end point determination was studied and based on which overall effects on drug-excipient compatibility using different hydrate forms of excipients were evaluated.

Evaluation of blotchy pigments in the anterior chamber angle as a sign of angle closure

PubMed Central

Rao, Harsha L; Mungale, Sachin C; Kumbar, Tukaram; Parikh, Rajul S; Garudadri, Chandra S

2012-01-01

Background: Blotchy pigments in the anterior chamber (AC) angle are considered diagnostic of primary angle closure (PAC). But there are no reports either on the prevalence of blotchy pigments in AC angles or the validity of this sign. Aims: To determine the prevalence of blotchy pigments in AC angles and to evaluate their relationship with glaucomatous optic neuropathy (GON) in eyes with occludable angles. Setting and Design: Cross-sectional, comparative study. Materials and Methods: Gonioscopy was performed in 1001 eyes of 526 subjects (245 eyes of 148 consecutive, occludable angle subjects and 756 eyes of 378 non-consecutive, open angle subjects), above 35 years of age. Quadrant-wise location of blotchy pigments was documented. Statistical Analysis: Odds of blotchy pigments in occludable angles against that in open angles were evaluated. Relationship of GON with blotchy pigments in occludable angle eyes was evaluated using a multivariate model. Results: Prevalence of blotchy pigments in occludable angles was 28.6% (95% CI, 22.9-34.3) and in open angles was 4.7% (95% CI, 3.2-6.3). Blotchy pigments were more frequently seen in inferior (16%) and superior quadrants (15%) of occludable angles, and inferior quadrant of open angles (4%). Odds of superior quadrant blotchy pigments in occludable angles were 33 times that in open angles. GON was seen in 107 occludable angle eyes. Blotchy pigments were not significantly associated with GON (odds ratio = 0.5; P = 0.1). Conclusions: Blotchy pigments were seen in 28.6% of occludable angle eyes and 4.7% of open angles eyes. Presence of blotchy pigments in the superior quadrant is more common in occludable angles. Presence of GON in occludable angle eyes was not associated with blotchy pigments. PMID:23202393

Personality of the tinnitus patient.

PubMed

House, P R

1981-01-01

Personality and coping mechanisms are related to patients' perceptions of their tinnitus. Although the occurrence of tinnitus is not unusual, its nature varies from infrequent, barely noticeable sound to an unrelenting, absorbing disturbance of critical significance. Tinnitus is a subjective complaint: the same level of tinnitus may be described by one patient as intolerable and by another as barely noticeable. Stress is intricately related to tinnitus: persons with severe tinnitus experience excessive stress. This has debilitating effects on their defences and coping can become very difficult. Patients may demonstrate a cluster of hysterical defences or a serious degree of depression. Many tinnitus patients focus on their problem, objectifying it and thus intensifying the disturbance. Most tinnitus patients can be helped by psychological intervention. A small percentage of tinnitus patients can be classified as disturbed, with borderline personalities. These patients are usually not suitable for therapy or biofeedback training. Tinnitus can be stress-related disorder. As a person is faced with conflict, physiological changes occur as a result of the "fight or flight" reaction. This state of stress can be responsible for the onset or exacerbation of a tinnitus episode. Treatment by management of stress can be successful, promoting relief through a shift of focus, repose from a state of tension, and support of constructive defences.

Degassing during quiescence as a trigger of magma ascent and volcanic eruptions

PubMed Central

Girona, Társilo; Costa, Fidel; Schubert, Gerald

2015-01-01

Understanding the mechanisms that control the start-up of volcanic unrest is crucial to improve the forecasting of eruptions at active volcanoes. Among the most active volcanoes in the world are the so-called persistently degassing ones (e.g., Etna, Italy; Merapi, Indonesia), which emit massive amounts of gas during quiescence (several kilotonnes per day) and erupt every few months or years. The hyperactivity of these volcanoes results from frequent pressurizations of the shallow magma plumbing system, which in most cases are thought to occur by the ascent of magma from deep to shallow reservoirs. However, the driving force that causes magma ascent from depth remains unknown. Here we demonstrate that magma ascent can be triggered by the passive release of gas during quiescence, which induces the opening of pathways connecting deep and shallow magma reservoirs. This top-down mechanism for volcanic eruptions contrasts with the more common bottom-up mechanisms in which magma ascent is only driven by processes occurring at depth. A cause-effect relationship between passive degassing and magma ascent can explain the fact that repose times are typically much longer than unrest times preceding eruptions, and may account for the so frequent unrest episodes of persistently degassing volcanoes. PMID:26666396

Tort law and medical malpractice insurance premiums.

PubMed

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

2006-01-01

This paper estimated the effects of tort law and insurer investment returns on physician malpractice insurance premiums. Data were collected on tort law from 1991 through 2004, and multivariate regression models, including fixed effects for state and year, were used to estimate the effect of changes in tort law on medical malpractice premiums. The premium consequences of national policy changes were simulated. The analysis found that the introduction of a new damage cap lowered malpractice premiums for internal medicine, general surgery, and obstetrics/gynecology by 17.3%, 20.7%, and 25.5%, respectively. Lowering damage caps by dollar 100,000 reduced premiums by 4%. Statutes of repose also resulted in lower premiums. No other tort law changes had the effect of lowering premiums. Simulation results indicate that a national cap of dollar 250,000 on awards for noneconomic damages in all states would imply premium savings of dollar 16.9 billion. Extending a dollar 250,000 cap to all states that do not currently have them would save dollar 1.4 billion annually, or about 8% of the total. A negative effect on malpractice premiums was found for the Dow Jones industrial average, but not for bond prices; effects of the Nasdaq index were not significant for internal medicine, but were marginally significant for surgery and obstetrics premiums.

NiTi Alloy Negator Springs for Long-Stroke Constant-Force Shape Memory Actuators: Modeling, Simulation and Testing

NASA Astrophysics Data System (ADS)

Spaggiari, Andrea; Dragoni, Eugenio; Tuissi, Ausonio

2014-07-01

This work aims at the experimental characterization and modeling validation of shape memory alloy (SMA) Negator springs. According to the classic engineering books on springs, a Negator spring is a spiral spring made of strip of metal wound on the flat with an inherent curvature such that, in repose, each coil wraps tightly on its inner neighbor. The main feature of a Negator springs is the nearly constant force displacement behavior in the unwinding of the strip. Moreover the stroke is very long, theoretically infinite, as it depends only on the length of the initial strip. A Negator spring made in SMA is built and experimentally tested to demonstrate the feasibility of this actuator. The shape memory Negator spring behavior can be modeled with an analytical procedure, which is in good agreement with the experimental test and can be used for design purposes. In both cases, the material is modeled as elastic in austenitic range, while an exponential continuum law is used to describe the martensitic behavior. The experimental results confirms the applicability of this kind of geometry to the shape memory alloy actuators, and the analytical model is confirmed to be a powerful design tool to dimension and predict the spring behavior both in martensitic and austenitic range.

Associations between malaria and local and global climate variability in five regions in Papua New Guinea.

PubMed

Imai, Chisato; Cheong, Hae-Kwan; Kim, Ho; Honda, Yasushi; Eum, Jin-Hee; Kim, Clara T; Kim, Jin Seob; Kim, Yoonhee; Behera, Swadhin K; Hassan, Mohd Nasir; Nealon, Joshua; Chung, Hyenmi; Hashizume, Masahiro

2016-01-01

Malaria is a significant public health issue in Papua New Guinea (PNG) as the burden is among the highest in Asia and the Pacific region. Though PNG's vulnerability to climate change and sensitivity of malaria mosquitoes to weather are well-documented, there are few in-depth epidemiological studies conducted on the potential impacts of climate on malaria incidence in the country. This study explored what and how local weather and global climate variability impact on malaria incidence in five regions of PNG. Time series methods were applied to evaluate the associations of malaria incidence with weather and climate factors, respectively. Local weather factors including precipitation and temperature and global climate phenomena such as El Niño-Southern Oscillation (ENSO), the ENSO Modoki, the Southern Annular Mode, and the Indian Ocean Dipole were considered in analyses. The results showed that malaria incidence was associated with local weather factors in most regions but at the different lag times and in directions. Meanwhile, there were trends in associations with global climate factors by geographical locations of study sites. Overall heterogeneous associations suggest the importance of location-specific approaches in PNG not only for further investigations but also public health interventions in repose to the potential impacts arising from climate change.

An investigation into shallow system dynamics during strombolian activity at Mt Etna using UV cameras, seismic data and modelling of gas flow

NASA Astrophysics Data System (ADS)

Pering, Tom D.; Tamburello, Giancarlo; McGonigle, Andrew J. S.; Aiuppa, Alessandro; James, Mike R.; Lane, Steve J.; Sciotto, Mariangela; Cannata, Andrea; Patanè, Domenico

2014-05-01

During rapid strombolian activity observed at the Bocca Nuova (BN) crater of Mt Etna on the 27th July 2012, ultra-violet cameras were used to measure SO2 emissions from the active vent over ≡ 30 minutes of activity. This resulted in the first determination of SO2 masses for strombolian activity at Etna, with individual bursts of ≡ 0.1 - 14 kg. By combining this with Multi-GAS measurements of gas ratios in the BN plume, we estimate a total gas mass for individual bursts of ≡ 0.2 - 165 kg. By calculating the degassing paths of typical H2O and CO2 contents for Etnean magmas and matching this with the measured CO2/SO2 ratio of ≡3 we estimate that the depth that gas decouples from the melt at 0.5 - 6.2 km. Statistical analysis of the repose time between bursts showed an average interval of ≡3 - 5 s with a maximum of ≡ 45 s. Plotting the repose time following bursts against their gas masses indicates that larger events were not followed rapidly by a subsequent event. The subsequent event also always had a significant emission speed, i.e. following larger events there was a minimum wait period and minimum emission speed for the subsequent burst. This could be the result of a number of different processes or effects: 1) bubble coalescence and the consequent faster rise of larger gas masses,, 2) the coalescence of ascending Taylor bubbles (slugs), 3) an atmospheric transport effect related to changes in magma level, and 4) the partial collapse of a foam or a form of trap-and-release mechanism. Subsequent analysis of the fluid dynamics was performed using several numerical models, including: Del Bello et al. (2012) to estimate magma and conduit parameters, Seyfried and Freundt (2000) with Llewellin et al. (2012) to estimate where transition to full slug flow occurs, and Noguiera et al. (2006) for the wake length of slugs. The use of these models in combination with the James et al. (2008) dynamic slug model suggests that coalescence between gas masses, reasonably assumed to be slugs, occurs more frequently in the upper ≡ 100 m of the conduit, where gas expansion becomes significant. The depth at which transition to slug flow occurs is similarly shallow. Comparison of individual burst events and a range of lags with filtered seismic displacement data from the EBCN seismic station of the INGV network, demonstrated no correlation between maximum peak-to-peak amplitude in the vertical component. Although, a tentative (due to the discrete 10 minute period used with omission of anomalous data) correlation of r2 = 0.88 exists for the sum of burst mass in a minute against equivalent RMS when offset by a lag of 2 minutes. Considering the approximate rise speed of gas masses, the location of gas at the time of correlation is estimated to be a depth of < ≡ 250 m.

Glaucoma

MedlinePlus

Open-angle glaucoma; Chronic glaucoma; Chronic open-angle glaucoma; Primary open-angle glaucoma; Closed-angle glaucoma; Narrow-angle glaucoma; Angle-closure glaucoma; Acute glaucoma; Secondary glaucoma; Congenital glaucoma; Vision ...

Evaluation of the anterior chamber angle in Asian Indian eyes by ultrasound biomicroscopy and gonioscopy.

PubMed

Kaushik, Sushmita; Jain, Rajeev; Pandav, Surinder Singh; Gupta, Amod

2006-09-01

To compare the ultrasound biomicroscopic measurement of the anterior chamber angle in Asian Indian eyes, with the angle width estimated by gonioscopy. Patients with open and closed angles attending a glaucoma clinic were recruited for the study. Temporal quadrants of the angles of patients were categorized by gonioscopy as Grade 0 to Grade 4, using Shaffer's classification. These angles were quantified by ultrasound biomicroscopy (UBM) using the following biometric characteristics: Angle opening distance at 250 micro (AOD 250) and 500 micro (AOD 500) from the scleral spur and trabecular meshwork-ciliary process distance (TCPD). The angles were further segregated as "narrow angles" (Schaffer's Grade 2 or less) and "open angles" (Schaffer's Grade 3 and 4). The UBM measurements were computed in each case and analyzed in relation to the gonioscopic angle evaluation. One hundred and sixty three eyes of 163 patients were analyzed. One hundred and six eyes had "narrow angles" and 57 eyes had "open angles" on gonioscopy. There was a significant difference among the mean UBM measurements of each angle grade estimated by gonioscopy (P < 0.001). The Pearson correlation coefficient between all UBM parameters and gonioscopy grades was significant at the 0.01 level. The mean AOD 250, AOD 500 and TCPD in narrow angles were 58+/-49 micro, 102+/-84 micro and 653+/-124 respectively, while it was 176+/-47 micro, 291+/-62 micro and 883+/-94 micro in eyes with open angles (P < 0.001) respectively. The angle width estimated by gonioscopy correlated significantly with the angle dimensions measured by UBM. Gonioscopy, though a subjective test, is a reliable method for estimation of the angle width.

A highly accurate dynamic contact angle algorithm for drops on inclined surface based on ellipse-fitting.

PubMed

Xu, Z N; Wang, S Y

2015-02-01

To improve the accuracy in the calculation of dynamic contact angle for drops on the inclined surface, a significant number of numerical drop profiles on the inclined surface with different inclination angles, drop volumes, and contact angles are generated based on the finite difference method, a least-squares ellipse-fitting algorithm is used to calculate the dynamic contact angle. The influences of the above three factors are systematically investigated. The results reveal that the dynamic contact angle errors, including the errors of the left and right contact angles, evaluated by the ellipse-fitting algorithm tend to increase with inclination angle/drop volume/contact angle. If the drop volume and the solid substrate are fixed, the errors of the left and right contact angles increase with inclination angle. After performing a tremendous amount of computation, the critical dimensionless drop volumes corresponding to the critical contact angle error are obtained. Based on the values of the critical volumes, a highly accurate dynamic contact angle algorithm is proposed and fully validated. Within nearly the whole hydrophobicity range, it can decrease the dynamic contact angle error in the inclined plane method to less than a certain value even for different types of liquids.

Anterior chamber angle assessment using gonioscopy and ultrasound biomicroscopy.

PubMed

Narayanaswamy, Arun; Vijaya, Lingam; Shantha, B; Baskaran, Mani; Sathidevi, A V; Baluswamy, Sukumar

2004-01-01

Comparison of anterior chamber angle measurements using ultrasound biomicroscopy (UBM) and gonioscopy. Five hundred subjects were evaluated for grading of angle width by the Shaffer method. UBM was done in the same group to document angle width, angle opening distance (AOD 500), and anterior chamber depth. Biometric parameters were documented in all subjects. UBM and gonioscopic findings were compared. A study was conducted in 282 men and 218 women with a mean age of 57.32 +/- 12.48 years. Gonioscopic grading was used to segregate occludable (slit-like, grades 1 and 2) from nonoccludable (grades 3 and 4) angles. Subjective assessment by gonioscopy resulted in an overestimation of angle width within the occludable group when compared with values obtained by UBM. This did not affect the segregation of occludable versus nonoccludable angles by gonioscopy. Biometric parameters in eyes with occludable angles were significantly lower in comparison with eyes with nonoccludable angles, except for lens thickness. AOD 500 correlated well with angle width. We concluded that clinical segregation into occludable and nonoccludable angles by an experienced observer using gonioscopy is fairly accurate. However, UBM is required for objective quantification of angles, and AOD 500 can be a reliable and standard parameter to grade angle width.

Le syndrome du canal d’Alcock ou névralgie pudendale : un diagnostic à ne pas méconnaître

PubMed Central

Ziouziou, Imad; Bennani, Hassan; Zizi, Mohamed; Karmouni, Tarik; Khader, Khalid El; Koutani, Abdellatif; Andaloussi, Ahmed Iben Attya

2013-01-01

Résumé Le syndrome du canal d’Alcock – ou névralgie pudendale – est lié à la compression chronique du nerf pudendal dans la fossette ischiorectale ou au niveau du ligament sacroépineux. Le diagnostic du syndrome d’Alcock est surtout clinique. Les examens complémentaires sont dominés par les explorations électrophysiologiques et le test de bloc anesthésique. Le diagnostic repose sur des critères bien précis, soit les critères de Nantes. La prise en charge doit être globale, comprenant un traitement médicamenteux, des infiltrations, des techniques de neuromodulation, et dans les cas graves ou résistants, un traitement chirurgical qui consiste à libérer le nerf pudendal. Les névralgies pudendales peuvent être rencontrées après traitement d’une incontinence urinaire d’effort par bande-lettes sous-urétrales (TVT). Ce syndrome motive des consultations en urologie, car la douleur intéresse le territoire du périnée et des organes génitaux. Des signes urinaires peuvent aussi accompagner cette douleur. Il est donc judicieux de connaître cette pathologie. PMID:23914265

Design and Flight Evaluation of a New Force-Based Flow Angle Probe

NASA Technical Reports Server (NTRS)

Corda, Stephen; Vachon, Michael Jacob

2006-01-01

A novel force-based flow angle probe was designed and flight tested on the NASA F-15B Research Testbed aircraft at NASA Dryden Flight Research Center. The prototype flow angle probe is a small, aerodynamic fin that has no moving parts. Forces on the prototype flow angle probe are measured with strain gages and correlated with the local flow angle. The flow angle probe may provide greater simplicity, greater robustness, and better access to flow measurements in confined areas relative to conventional moving vane-type flow angle probes. Flight test data were obtained at subsonic, transonic, and supersonic Mach numbers to a maximum of Mach 1.70. Flight conditions included takeoff, landing, straight and level flight, flight at higher aircraft angles of attack, and flight at elevated g-loadings. Flight test maneuvers included angle-of-attack and angle-of-sideslip sweeps. The flow angle probe-derived flow angles are compared with those obtained with a conventional moving vane probe. The flight tests validated the feasibility of a force-based flow angle measurement system.

Angle performance on optima MDxt

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

David, Jonathan; Kamenitsa, Dennis

2012-11-06

Angle control on medium current implanters is important due to the high angle-sensitivity of typical medium current implants, such as halo implants. On the Optima MDxt, beam-to-wafer angles are controlled in both the horizontal and vertical directions. In the horizontal direction, the beam angle is measured through six narrow slits, and any angle adjustment is made by electrostatically steering the beam, while cross-wafer beam parallelism is adjusted by changing the focus of the electrostatic parallelizing lens (P-lens). In the vertical direction, the beam angle is measured through a high aspect ratio mask, and any angle adjustment is made by slightlymore » tilting the wafer platen prior to implant. A variety of tests were run to measure the accuracy and repeatability of Optima MDxt's angle control. SIMS profiles of a high energy, channeling sensitive condition show both the cross-wafer angle uniformity, along with the small-angle resolution of the system. Angle repeatability was quantified by running a channeling sensitive implant as a regular monitor over a seven month period and measuring the sheet resistance-to-angle sensitivity. Even though crystal cut error was not controlled for in this case, when attributing all Rs variation to angle changes, the overall angle repeatability was measured as 0.16 Degree-Sign (1{sigma}). A separate angle repeatability test involved running a series of V-curves tests over a four month period using low crystal cut wafers selected from the same boule. The results of this test showed the angle repeatability to be <0.1 Degree-Sign (1{sigma}).« less

Modeling contact angle hysteresis of a liquid droplet sitting on a cosine wave-like pattern surface.

PubMed

Promraksa, Arwut; Chen, Li-Jen

2012-10-15

A liquid droplet sitting on a hydrophobic surface with a cosine wave-like square-array pattern in the Wenzel state is simulated by using the Surface Evolver to determine the contact angle. For a fixed drop volume, multiple metastable states are obtained at two different surface roughnesses. Unusual and non-circular shape of the three-phase contact line of a liquid droplet sitting on the model surface is observed due to corrugation and distortion of the contact line by structure of the roughness. The contact angle varies along the contact line for each metastable state. The maximum and minimum contact angles among the multiple metastable states at a fixed viewing angle correspond to the advancing and the receding contact angles, respectively. It is interesting to observe that the advancing/receding contact angles (and contact angle hysteresis) are a function of viewing angle. In addition, the receding (or advancing) contact angles at different viewing angles are determined at different metastable states. The contact angle of minimum energy among the multiple metastable states is defined as the most stable (equilibrium) contact angle. The Wenzel model is not able to describe the contact angle along the three-phase contact line. The contact angle hysteresis at different drop volumes is determined. The number of the metastable states increases with increasing drop volume. Drop volume effect on the contact angles is also discussed. Crown Copyright © 2012. Published by Elsevier Inc. All rights reserved.

[Comparison of anterior chamber angle examination by UBM, SL-OCT and gonioscopy].

PubMed

Liu, Rui-jue; Wang, Men; Xia, Wen-tao; Yu, Xiao-ying; Chen, Jie-min; Zhou, Shu; Peng, Shu-ya; Liu, Dong-mei

2014-08-01

To compare the agreement of anterior chamber angle examination by ultrasound biomicroscope (UBM), slit lamp optical coherence tomography (SL-OCT), and gonioscopy in angle recession and angle closure. The anterior chamber angle was measured with UBM, SL-OCT and gonioscopy in turns for temporal, nasal, superior and inferior quadrant in the same dark room. The results were compared with the agreement of the three methods in angle recession and angle closure by χ2 test and Kappa test. There were no statistically significant differences of the three methods in testing angle closure and angle recession (P>0.05). The consistency of UBM and gonioscopy was better (Kappa value of 0.882) than that of SL-OCT and gonioscopy (Kappa value of 0.624). When testing angle recession, UBM is better than SL-OCT with gonioscopy as the standard. When testing angle closure, UBM, SL-OCT and gonioscopy have good agreement.

Metric analysis of basal sphenoid angle in adult human skulls

PubMed Central

Netto, Dante Simionato; Nascimento, Sergio Ricardo Rios; Ruiz, Cristiane Regina

2014-01-01

Objective To analyze the variations in the angle basal sphenoid skulls of adult humans and their relationship to sex, age, ethnicity and cranial index. Methods The angles were measured in 160 skulls belonging to the Museum of the Universidade Federal de São Paulo Department of Morphology. We use two flexible rules and a goniometer, having as reference points for the first rule the posterior end of the ethmoidal crest and dorsum of the sella turcica, and for the second rule the anterior margin of the foramen magnum and clivus, measuring the angle at the intersection of two. Results The average angle was 115.41°, with no statistical correlation between the value of the angle and sex or age. A statistical correlation was noted between the value of the angle and ethnicity, and between the angle and the horizontal cranial index. Conclusions The distribution of the angle basal sphenoid was the same in sex, and there was correlation between the angle and ethnicity, being the proportion of non-white individuals with an angle >125° significantly higher than that of whites with an angle >125°. There was correlation between the angle and the cranial index, because skulls with higher cranial index tend to have higher basiesfenoidal angle too. PMID:25295452

Angle amplifier based on multiplexed volume holographic gratings

NASA Astrophysics Data System (ADS)

Cao, Liangcai; Zhao, Yifei; He, Qingsheng; Jin, Guofan

2008-03-01

Angle amplifier of laser beam scanner is a widely used device in optical systems. Volume holographic optical elements can be applied in the angle amplifier. Compared with the traditional angle amplifier, it has the advantages of high angle resolution, high diffraction efficiency, small size, and high angle magnification and flexible design. Bragg anglewavelength- compensating recording method is introduced. Because of the Bragg compensatory relation between angle and wavelength, this device could be recorded at another wavelength. The design of the angle amplifier recording at the wavelength of 514.2nm for the working wavelength of 632.8nm is described. An optical setup for recording the angle amplifier device is designed and discussed. Experimental results in the photorefractive crystal Fe:LiNbO 3 demonstrate the feasibility of the angle amplifier scheme.

Optimum Projection Angle for Attaining Maximum Distance in a Soccer Punt Kick

PubMed Central

Linthorne, Nicholas P.; Patel, Dipesh S.

2011-01-01

To produce the greatest horizontal distance in a punt kick the ball must be projected at an appropriate angle. Here, we investigated the optimum projection angle that maximises the distance attained in a punt kick by a soccer goalkeeper. Two male players performed many maximum-effort kicks using projection angles of between 10° and 90°. The kicks were recorded by a video camera at 100 Hz and a 2 D biomechanical analysis was conducted to obtain measures of the projection velocity, projection angle, projection height, ball spin rate, and foot velocity at impact. The player’s optimum projection angle was calculated by substituting mathematical equations for the relationships between the projection variables into the equations for the aerodynamic flight of a soccer ball. The calculated optimum projection angles were in agreement with the player’s preferred projection angles (40° and 44°). In projectile sports even a small dependence of projection velocity on projection angle is sufficient to produce a substantial shift in the optimum projection angle away from 45°. In the punt kicks studied here, the optimum projection angle was close to 45° because the projection velocity of the ball remained almost constant across all projection angles. This result is in contrast to throwing and jumping for maximum distance, where the projection velocity the athlete is able to achieve decreases substantially with increasing projection angle and so the optimum projection angle is well below 45°. Key points The optimum projection angle that maximizes the distance of a punt kick by a soccer goalkeeper is about 45°. The optimum projection angle is close to 45° because the projection velocity of the ball is almost the same at all projection angles. This result is in contrast to throwing and jumping for maximum distance, where the optimum projection angle is well below 45° because the projection velocity the athlete is able to achieve decreases substantially with increasing projection angle. PMID:24149315

Anisotropic perception of visual angle: implications for the horizontal-vertical illusion, overconstancy of size, and the moon illusion.

PubMed

Higashiyama, A

1992-03-01

Three experiments investigated anisotropic perception of visual angle outdoors. In Experiment 1, scales for vertical and horizontal visual angles ranging from 20 degrees to 80 degrees were constructed with the method of angle production (in which the subject reproduced a visual angle with a protractor) and the method of distance production (in which the subject produced a visual angle by adjusting viewing distance). In Experiment 2, scales for vertical and horizontal visual angles of 5 degrees-30 degrees were constructed with the method of angle production and were compared with scales for orientation in the frontal plane. In Experiment 3, vertical and horizontal visual angles of 3 degrees-80 degrees were judged with the method of verbal estimation. The main results of the experiments were as follows: (1) The obtained angles for visual angle are described by a quadratic equation, theta' = a + b theta + c theta 2 (where theta is the visual angle; theta', the obtained angle; a, b, and c, constants). (2) The linear coefficient b is larger than unity and is steeper for vertical direction than for horizontal direction. (3) The quadratic coefficient c is generally smaller than zero and is negatively larger for vertical direction than for horizontal direction. And (4) the obtained angle for visual angle is larger than that for orientation. From these results, it was possible to predict the horizontal-vertical illusion, over-constancy of size, and the moon illusion.

Anterior Segment Imaging Predicts Incident Gonioscopic Angle Closure.

PubMed

Baskaran, Mani; Iyer, Jayant V; Narayanaswamy, Arun K; He, Yingke; Sakata, Lisandro M; Wu, Renyi; Liu, Dianna; Nongpiur, Monisha E; Friedman, David S; Aung, Tin

2015-12-01

To investigate the incidence of gonioscopic angle closure after 4 years in subjects with gonioscopically open angles but varying degrees of angle closure detected on anterior segment optical coherence tomography (AS OCT; Visante; Carl Zeiss Meditec, Dublin, CA) at baseline. Prospective, observational study. Three hundred forty-two subjects, mostly Chinese, 50 years of age or older, were recruited, of whom 65 were controls with open angles on gonioscopy and AS OCT at baseline, and 277 were cases with baseline open angles on gonioscopy but closed angles (1-4 quadrants) on AS OCT scans. All subjects underwent gonioscopy and AS OCT at baseline (horizontal and vertical single scans) and after 4 years. The examiner performing gonioscopy was masked to the baseline and AS OCT data. Angle closure in a quadrant was defined as nonvisibility of the posterior trabecular meshwork by gonioscopy and visible iridotrabecular contact beyond the scleral spur in AS OCT scans. Gonioscopic angle closure in 2 or 3 quadrants after 4 years. There were no statistically significant differences in age, ethnicity, or gender between cases and controls. None of the control subjects demonstrated gonioscopic angle closure after 4 years. Forty-eight of the 277 subjects (17.3%; 95% confidence interval [CI], 12.8-23; P < 0.0001) with at least 1 quadrant of angle closure on AS OCT at baseline demonstrated gonioscopic angle closure in 2 or more quadrants, whereas 28 subjects (10.1%; 95% CI, 6.7-14.6; P < 0.004) demonstrated gonioscopic angle closure in 3 or more quadrants after 4 years. Individuals with more quadrants of angle closure on baseline AS OCT scans had a greater likelihood of gonioscopic angle closure developing after 4 years (P < 0.0001, chi-square test for trend for both definitions of angle closure). Anterior segment OCT imaging at baseline predicts incident gonioscopic angle closure after 4 years among subjects who have gonioscopically open angles and iridotrabecular contact on AS OCT at baseline. Copyright © 2015 American Academy of Ophthalmology. All rights reserved.

Cross Flow Parameter Calculation for Aerodynamic Analysis

NASA Technical Reports Server (NTRS)

Norman, David, Jr. (Inventor)

2014-01-01

A system and method for determining a cross flow angle for a feature on a structure. A processor unit receives location information identifying a location of the feature on the structure, determines an angle of the feature, identifies flow information for the location, determines a flow angle using the flow information, and determines the cross flow angle for the feature using the flow angle and the angle of the feature. The flow information describes a flow of fluid across the structure. The flow angle comprises an angle of the flow of fluid across the structure for the location of the feature.

[Study of the relationship between congenital missing of the third molar and the development of the mandibular angle].

PubMed

Chen, Yan-Na; Zheng, Bo-Wen; Liu, Yi

2017-02-01

Based on the research of the congenital missing of the third molar and the missing number, the relationship beteen congenital missing of the third molar and the development of the mandibular angle was evaluated. Patients were divided into experimental group and control group, the experimental group included 227 patients, each had at least one of the third molars congenital lost; 227 patients who had four third molar were selected as control group. Winceph software was used to measure the lateral cephalograms. SPSS17.0 software package was used to perform statistical analysis. Gonial angle, upper Gonial angle and lower Gonial angle between the experimental group and the control group showed significant difference and the values in the experimental group were significantly smaller than in the control group, but there was no gender difference between the two groups.There was no difference between Gonial angle, upper Gonial angle,lower Gonial angle and the missing number of the third molar. There is a close relationship between congenital missing third molar and Gonial angle, upper Gonial angle, lower Gonial angle, but there is no significant association with gender and the patients with congenital missing third molar have shorter craniofacial structure. Congenital missing number of the third molar has no significant association with Gonial angle, upper Gonial angle and lower Gonial angle.

[Spectral Study on the Effects of Angle-Tuned Filter Wedge Angle Parameter to Reflecting Characteristics].

PubMed

Yu, Kan; Huang, De-xiu; Yin, Juan-juan; Bao, Jia-qi

2015-08-01

Three-port tunable optical filter is a key device in the all-optic intelligent switching network and dense wavelength division multiplexing system. The characteristics of the reflecting spectrum, especially the reflectivity and the isolation degree are very important to the three-port filter. Angle-tuned thin film filter is widely used as a three-port tunable filter for its high rectangular degree and good temperature stability. The characteristics of the reflecting spectrum are greatly influenced not only by the incident angle, but also by the wedge angle parameter of the non-paralleled wedge thin film filter. In the present paper, the influences of the wedge angle parameter to the reflectivity and the half bandwidth are analyzed, and the reflecting spectrum characterstics are simulationed in different wedge angle parameter and polarity. The wedge angle-tuned thin film filter with 0.8° wedge angle parameter is fabricated. The experimental results show that keeping the wedge angle the same orientation to the incident angle will worsen the reflectivity and the rectangular degree of the reflecting spectrum. However, keeping the wedge angle orientation reverse to the incident angle will enhance the reflectivity and decrease the bandwidth, which will give higher reflectivity and isolation degree to the three-port filter than that of high parallel degree angle-tuned thin film filter.

Influence of knee flexion angle and transverse drill angle on creation of femoral tunnels in double-bundle anterior cruciate ligament reconstruction using the transportal technique: Three-dimensional computed tomography simulation analysis.

PubMed

Choi, Chong Hyuk; Kim, Sung-Jae; Chun, Yong-Min; Kim, Sung-Hwan; Lee, Su-Keon; Eom, Nam-Kyu; Jung, Min

2018-01-01

The purpose of this study was to find appropriate flexion angle and transverse drill angle for optimal femoral tunnels of anteromedial (AM) bundle and posterolateral (PL) bundle in double-bundle ACL reconstruction using transportal technique. Thirty three-dimensional knee models were reconstructed. Knee flexion angles were altered from 100° to 130° at intervals of 10°. Maximum transverse drill angle (MTA), MTA minus 10° and 20° were set up. Twelve different tunnels were determined by four flexion angles and three transverse drill angles for each bundle. Tunnel length, wall breakage, inter-tunnel communication and graft-bending angle were assessed. Mean tunnel length of AM bundle was >30mm at 120° and 130° of flexion in all transverse drill angles. Mean tunnel length of PL bundle was >30mm during every condition. There were ≥1 cases of wall breakage except at 120° and 130° of flexion with MTA for AM bundle. There was no case of wall breakage for PL bundle. Considering inter-tunnel gap of >2mm without communication and obtuse graft-bending angle, 120° of flexion and MTA could be recommended as optimal condition for femoral tunnels of AM and PL bundles. Flexion angle and transverse drill angle had combined effect on femoral tunnel in double-bundle ACL reconstruction using transportal technique. Achieving flexion angle of 120° and transverse drill angle close to the medial femoral condyle could be recommended as optimal condition for femoral tunnels of AM and PL bundles to avoid insufficient tunnel length, wall breakage, inter-tunnel communication and acute graft-bending angle. Copyright © 2017 Elsevier B.V. All rights reserved.

Angular position of the cleat according to torsional parameters of the cyclist's lower limb.

PubMed

Ramos-Ortega, Javier; Domínguez, Gabriel; Castillo, José Manuel; Fernández-Seguín, Lourdes; Munuera, Pedro V

2014-05-01

The aim of this work was to study the relationship of torsional and rotational parameters of the lower limb with a specific angular position of the cleat to establish whether these variables affect the adjustment of the cleat. Correlational study. Motion analysis laboratory. Thirty-seven male cyclists of high performance. The variables studied of the cyclist's lower limb were hip rotation (internal and external), tibial torsion angle, Q angle, and forefoot adductus angle. The cleat angle was measured through a photograph of the sole and with an Rx of this using the software AutoCAD 2008. The variables were photograph angle (photograph), the variable denominated cleat-tarsus minor angle, and a variable denominated cleat-second metatarsal angle (Rx). Analysis included the intraclass correlation coefficient for the reliability of the measurements, Student's t test performed on the dependent variables to compare side, and the multiple linear regression models were calculated using the software SPSS 15.0 for Windows. The Student's t test performed on the dependent variables to compare side showed no significant differences (P = 0.209 for the photograph angle, P = 0.735 for the cleat-tarsus minor angle, and P = 0.801 for the cleat-second metatarsal angle). Values of R and R2 for the photograph angle model were 0.303 and 0.092 (P = 0.08), the cleat/tarsus minor angle model were 0.683 and 0.466 (P < 0.001), and the cleat/second metatarsal angle model were 0.618 and 0.382, respectively (P < 0.001). The equation given by the model was cleat-tarsus minor angle = 75.094 - (0.521 × forefoot adductus angle) + (0.116 × outward rotation of the hips) + (0.220 × Q angle).

Evaluation of the Anterior Segment Angle-to-Angle Scan of Cirrus High-Definition Optical Coherence Tomography and Comparison With Gonioscopy and With the Visante OCT.

PubMed

Tun, Tin A; Baskaran, Mani; Tan, Shayne S; Perera, Shamira A; Aung, Tin; Husain, Rahat

2017-01-01

To evaluate the diagnostic performance of the anterior segment angle-to-angle scan of the Cirrus high-definition optical coherence tomography (HD-OCT) in detecting eyes with closed angles. All subjects underwent dark-room gonioscopy by an ophthalmologist. A technician performed anterior segment imaging with Cirrus (n = 202) and Visante OCT (n = 85) under dark-room conditions. All eyes were categorized by two masked graders as per number of closed quadrants. Each quadrant of anterior chamber angle was categorized as a closed angle if posterior trabecular meshwork could not be seen on gonioscopy or if there was any irido-corneal contact anterior to scleral spur in Cirrus and Visante images. An eye was graded as having a closed angle if two or more quadrants were closed. Agreement and area under the curve (AUC) were performed. There were 50 (24.8%) eyes with closed angles. The agreements of closed-angle diagnosis (by eye) between Cirrus HD-OCT and gonioscopy (k = 0.59; 95% confidence interval (CI) 0.45-0.72; AC1 = 0.76) and between Cirrus and Visante OCT (k = 0.65; 95% CI 0.48-0.82, AC1 = 0.77) were moderate. The AUC for diagnosing the eye with gonioscopic closed angle by Cirrus HD-OCT was good (AUC = 0.86; sensitivity = 83.33; specificity = 77.78). The diagnostic performance of Cirrus HD-OCT in detecting the eyes with closed angles was similar to that of Visante (AUC 0.87 vs. 0.9, respectively; P = 0.51). The anterior segment angle-to-angle scans of Cirrus HD-OCT demonstrated similar diagnostic performance as Visante in detecting gonioscopic closed angles. The agreement between Cirrus and gonioscopy for detecting eyes with closed angles was moderate.

Changes in Anterior Segment Morphology and Predictors of Angle Widening after Laser Iridotomy in South Indian Eyes.

PubMed

Zebardast, Nazlee; Kavitha, Srinivasan; Krishnamurthy, Palaniswamy; Friedman, David S; Nongpiur, Monisha E; Aung, Tin; Quigley, Harry A; Ramulu, Pradeep Y; Venkatesh, Rengaraj

2016-12-01

To compare anterior segment optical coherence tomography (ASOCT) angle morphology before and after laser peripheral iridotomy (LPI) in a cohort of South Indian subjects with primary angle-closure suspect (PACS) or primary angle-closure/primary angle-closure glaucoma (PAC/PACG) and to examine baseline parameters associated with angle widening. Prospective observational study. A total of 244 subjects aged ≥30 years with PACS or PAC/PACG in at least 1 eye. The ASOCT images and angle gonioscopic grades were analyzed for all subjects at baseline and 2 weeks after LPI. Multivariable linear and logistic regression models were used to determine predictors of angle widening (change in mean angle opening distance [AOD750]) and angle opening (all 4 quadrants with trabecular meshwork [TM] visible on gonioscopy after LPI). Change in ASOCT parameters with LPI and baseline predictors of angle widening. Laser peripheral iridotomy resulted in angle widening on ASOCT with significant increases in AOD750, angle recess area, and trabecular iris surface area (P < 0.05 for all). Gonioscopically, 44.7% of all subjects had open angles in all 4 quadrants after LPI, with a greater percentage of angles open in the PACS group compared with the PAC/PACG group (52.4% vs. 36.4%; P = 0.01). In multivariable regression analyses, greater postoperative angle widening as defined by change in AOD750 was associated with shorter baseline AOD750 and axial length, and greater baseline anterior chamber depth, iris curvature, and lens vault (P ≤ 0.002 for all). Gonioscopic angle opening after LPI was more common with wider baseline angle width (modified Shaffer grade) and lower cup-to-disc ratio (P < 0.001 for both). In a South Indian population with PACS or PAC/PACG, LPI results in significant anterior chamber angle widening seen on both ASOCT and gonioscopy, although some degree of persistent iridotrabecular contact was present in approximately half of PACS eyes and approximately two thirds of PAC/PACG eyes on gonioscopy. The greatest widening by ASOCT was observed in eyes with features most consistent with greater baseline pupillary block. Copyright © 2016 American Academy of Ophthalmology. All rights reserved.

Enjoyment of Euclidean Planar Triangles

ERIC Educational Resources Information Center

Srinivasan, V. K.

2013-01-01

This article adopts the following classification for a Euclidean planar [triangle]ABC, purely based on angles alone. A Euclidean planar triangle is said to be acute angled if all the three angles of the Euclidean planar [triangle]ABC are acute angles. It is said to be right angled at a specific vertex, say B, if the angle ?ABC is a right angle…

The Semiotic and Conceptual Genesis of Angle

ERIC Educational Resources Information Center

Tanguay, Denis; Venant, Fabienne

2016-01-01

In the present study, we try to understand how students at the end of primary school conceive of angle: Is an angle a magnitude for them or a geometric figure, and how do they manage to coordinate the two aspects in their understanding of the concepts of angle and of angle measurement? With the aim of better grasping the way "angle" is…

Hong's grading for evaluating anterior chamber angle width.

PubMed

Kim, Seok Hwan; Kang, Ja Heon; Park, Ki Ho; Hong, Chul

2012-11-01

To compare Hong's grading method with anterior segment optical coherence tomography (AS-OCT), gonioscopy, and the dark-room prone-position test (DRPT) for evaluating anterior chamber width. The anterior chamber angle was graded using Hong's grading method, and Hong's angle width was calculated from the arctangent of Hong's grades. The correlation between Hong's angle width and AS-OCT parameters was analyzed. The area under the receiver operating characteristic curve (AUC) for Hong's grading method when discriminating between narrow and open angles as determined by gonioscopy was calculated. Correlation analysis was performed between Hong's angle width and intraocular pressure (IOP) changes determined by DRPT. A total of 60 subjects were enrolled. Of these subjects, 53.5 % had a narrow angle. Hong's angle width correlated significantly with the AS-OCT parameters (r = 0.562-0.719, P < 0.01). A Bland-Altman plot showed relatively good agreement between Hong's angle width and the angle width obtained by AS-OCT. The ability of Hong's grading method to discriminate between open and narrow angles was good (AUC = 0.868, 95 % CI 0.756-0.942). A significant linear correlation was found between Hong's angle width and IOP change determined by DRPT (r = -0.761, P < 0.01). Hong's grading method is useful for detecting narrow angles. Hong's grading correlated well with AS-OCT parameters and DRPT.

Detection of primary angle closure using anterior segment optical coherence tomography in Asian eyes.

PubMed

Nolan, Winifred P; See, Jovina L; Chew, Paul T K; Friedman, David S; Smith, Scott D; Radhakrishnan, Sunita; Zheng, Ce; Foster, Paul J; Aung, Tin

2007-01-01

To evaluate noncontact anterior segment optical coherence technology (AS-OCT) as a qualitative method of imaging the anterior chamber angle and to determine its ability to detect primary angle closure when compared with gonioscopy in Asian subjects. Prospective observational case series. Two hundred three subjects were recruited from glaucoma clinics in Singapore with diagnoses of primary angle closure, primary open-angle glaucoma, ocular hypertension, or cataract. Both eyes (if eligible) of each patient were included in the study. Exclusion criteria were pseudophakia or previous glaucoma surgery. Images of the nasal, temporal, and inferior angles were obtained with AS-OCT in dark and then light conditions. Gonioscopic angle width was graded using the Spaeth classification for each quadrant in low lighting conditions. Angle closure was defined by AS-OCT as contact between the peripheral iris and angle wall anterior to the scleral spur and by gonioscopy as a Spaeth grade of 0 degree (posterior trabecular meshwork not visible). Comparison of the 2 methods in detecting angle closure was done by eye and by individual. Sensitivities and specificities of AS-OCT were calculated using gonioscopy as the reference standard. Complete data were available for 342 eyes of 200 patients. Of the patients, 70.9% had a clinical diagnosis of treated or untreated primary angle closure. Angle closure in > or =1 quadrants was detected by AS-OCT in 142 (71%) patients (228 [66.7%] eyes) and by gonioscopy in 99 (49.5%) patients (152 [44.4%] eyes). The inferior angle was closed more frequently than the nasal or temporal quadrants using both AS-OCT and gonioscopy. When performed under dark conditions, AS-OCT identified 98% of those subjects found to have angle closure on gonioscopy (95% confidence interval [CI], 92.2-99.6) and led to the characterization of 44.6% of those found to have open angles on gonioscopy to have angle closure as well. With gonioscopy as the reference standard, specificity of AS-OCT in the dark was 55.4% (95% CI, 45.2-65.2) for detecting individuals with angle closure. Anterior segment OCT is a rapid noncontact method of imaging angle structures. It is highly sensitive in detecting angle closure when compared with gonioscopy. More persons are found to have closed angles with AS-OCT than with gonioscopy.

Individualized optimal release angles in discus throwing.

PubMed

Leigh, Steve; Liu, Hui; Hubbard, Mont; Yu, Bing

2010-02-10

The purpose of this study was to determine individualized optimal release angles for elite discus throwers. Three-dimensional coordinate data were obtained for at least 10 competitive trials for each subject. Regression relationships between release speed and release angle, and between aerodynamic distance and release angle were determined for each subject. These relationships were linear with subject-specific characteristics. The subject-specific relationships between release speed and release angle may be due to subjects' technical and physical characteristics. The subject-specific relationships between aerodynamic distance and release angle may be due to interactions between the release angle, the angle of attack, and the aerodynamic distance. Optimal release angles were estimated for each subject using the regression relationships and equations of projectile motion. The estimated optimal release angle was different for different subjects, and ranged from 35 degrees to 44 degrees . The results of this study demonstrate that the optimal release angle for discus throwing is thrower-specific. The release angles used by elite discus throwers in competition are not necessarily optimal for all discus throwers, or even themselves. The results of this study provide significant information for understanding the biomechanics of discus throwing techniques. Copyright 2009 Elsevier Ltd. All rights reserved.

Equilibrium contact angle or the most-stable contact angle?

PubMed

Montes Ruiz-Cabello, F J; Rodríguez-Valverde, M A; Cabrerizo-Vílchez, M A

2014-04-01

It is well-established that the equilibrium contact angle in a thermodynamic framework is an "unattainable" contact angle. Instead, the most-stable contact angle obtained from mechanical stimuli of the system is indeed experimentally accessible. Monitoring the susceptibility of a sessile drop to a mechanical stimulus enables to identify the most stable drop configuration within the practical range of contact angle hysteresis. Two different stimuli may be used with sessile drops: mechanical vibration and tilting. The most stable drop against vibration should reveal the changeless contact angle but against the gravity force, it should reveal the highest resistance to slide down. After the corresponding mechanical stimulus, once the excited drop configuration is examined, the focus will be on the contact angle of the initial drop configuration. This methodology needs to map significantly the static drop configurations with different stable contact angles. The most-stable contact angle, together with the advancing and receding contact angles, completes the description of physically realizable configurations of a solid-liquid system. Since the most-stable contact angle is energetically significant, it may be used in the Wenzel, Cassie or Cassie-Baxter equations accordingly or for the surface energy evaluation. © 2013 Elsevier B.V. All rights reserved.

Calculating Angle Lambda (λ) Using Zernike Tilt Measurements in Specular Reflection Corneal Topography

PubMed Central

Braaf, Boy; van de Watering, Thomas Christiaan; Spruijt, Kees; van der Heijde, Rob G.L.; Sicam, Victor Arni D.P.

2010-01-01

Purpose To develop a method to calculate the angle λ of the human eye using Zernike tilt measurements in specular reflection corneal topography. Methods The meaning of Zernike tilt in specular reflection corneal topography is demonstrated by measurements on translated artificial surfaces using the VU Topographer. The relationship derived from the translation experiments is used to determine the angle λ. Corneal surfaces are measured for a set of eight different fixation points, for which tilt angles ρ are obtained from the Zernike tilt coefficients. The angles ρ are used with respect to the fixation target angles to determine angle λ by fitting a geometrical model. This method is validated with Orbscan II's angle-κ measurements in 9 eyes. Results The translation experiments show that the Zernike tilt coefficient is directly related to an angle ρ, which describes a tilt orientation of the cornea and can therefore be used to derive a value for angle λ. A significant correlation exists between measured values for angle λ with the VU Topographer and the angle κ with the Orbscan II (r=0.95, P<0.001). A Bland-Altman plot indicates a mean difference of -0.52 degrees between the two instruments, but this is not statistically significant as indicated by a matched-pairs Wilcoxon signed-rank test (P≤0.1748). The mean precision for measuring angle λ using the VU topographer is 0.6±0.3 degrees. Conclusion The method described above to determine angle λ is sufficiently repeatable and performs similarly to the angle-κ measurements made with the Orbscan II.

Transperineal ultrasonography in stress urinary incontinence: The significance of urethral rotation angles.

PubMed

Al-Saadi, Wasan Ismail

2016-03-01

To assess, using transperineal ultrasonography (TPUS), the numerical value of the rotation of the bladder neck [represented by the difference in the anterior (α angle) and posterior urethral angles (β angle)] at rest and straining, in continent women and women with stress urinary incontinence (SUI), to ascertain if there are significant differences in the angles of rotation (Rα and Rβ) between the groups. In all, 30 women with SUI (SUI group) and 30 continent women (control group) were included. TPUS was performed at rest and straining (Valsalva manoeuver), and the threshold value for the urethral angles (α and β angles) for each group were estimated. The degree of rotation for each angle was calculated and was considered as the angle of rotation. Both the α and β angles were significantly different between the groups at rest and straining, and there was a significant difference in the mean increment in the value of each angle. Higher values of increment (higher rotation angles) were reported in the SUI group for both the α and β angles compared with those of the control group [mean (SD) Rα SUI group 19.43 (12.76) vs controls 10.53 (2.98) °; Rβ SUI group 28.30 (12.96) vs controls 16.33 (10.8) °; P < 0.001]. Urethral rotation angles may assist in the assessment and diagnosis of patients with SUI, which may in turn reduce the need for more sophisticated urodynamic studies.

Angle-stable and compressed angle-stable locking for tibiotalocalcaneal arthrodesis with retrograde intramedullary nails. Biomechanical evaluation.

PubMed

Mückley, Thomas; Hoffmeier, Konrad; Klos, Kajetan; Petrovitch, Alexander; von Oldenburg, Geert; Hofmann, Gunther O

2008-03-01

Retrograde intramedullary nailing is an established procedure for tibiotalocalcaneal arthrodesis. The goal of this study was to evaluate the effects of angle-stable locking or compressed angle-stable locking on the initial stability of the nails and on the behavior of the constructs under cyclic loading conditions. Tibiotalocalcaneal arthrodesis was performed in fifteen third-generation synthetic bones and twenty-four fresh-frozen cadaver legs with use of retrograde intramedullary nailing with three different locking modes: a Stryker nail with compressed angle-stable locking, a Stryker nail with angle-stable locking, and a statically locked Biomet nail. Analyses were performed of the initial stability of the specimens (range of motion) and the laxity of the constructs (neutral zone) in dorsiflexion/plantar flexion, varus/valgus, and external rotation/internal rotation. Cyclic testing up to 100,000 cycles was also performed. The range of motion and the neutral zone in dorsiflexion/plantar flexion at specific cycle increments were determined. In both bone models, the intramedullary nails with compressed angle-stable locking and those with angle-stable locking were significantly superior, in terms of a smaller range of motion and neutral zone, to the statically locked nails. The compressed angle-stable nails were superior to the angle-stable nails only in the synthetic bone model, in external/internal rotation. Cyclic testing showed the nails with angle-stable locking and those with compressed angle-stable locking to have greater stability in both models. In the synthetic bone model, compressed angle-stable locking was significantly better than angle-stable locking; in the cadaver bone model, there was no significant difference between these two locking modes. During cyclic testing, five statically locked nails in the cadaver bone model failed, whereas one nail with angle-stable locking and one with compressed angle-stable locking failed. Regardless of the bone model, the nails with angle-stable or compressed angle-stable locking had better initial stability and better stability following cycling than did the nails with static locking.

Hysteresis of Contact Angle of Sessile Droplets on Smooth Homogeneous Solid Substrates via Disjoining/Conjoining Pressure.

PubMed

Kuchin, I; Starov, V

2015-05-19

A theory of contact angle hysteresis of liquid droplets on smooth, homogeneous solid substrates is developed in terms of the shape of the disjoining/conjoining pressure isotherm and quasi-equilibrium phenomena. It is shown that all contact angles, θ, in the range θr < θ < θa, which are different from the unique equilibrium contact angle θ ≠ θe, correspond to the state of slow "microscopic" advancing or receding motion of the liquid if θe < θ < θa or θr < θ < θe, respectively. This "microscopic" motion almost abruptly becomes fast "macroscopic" advancing or receding motion after the contact angle reaches the critical values θa or θr, correspondingly. The values of the static receding, θr, and static advancing, θa, contact angles in cylindrical capillaries were calculated earlier, based on the shape of disjoining/conjoining pressure isotherm. It is shown now that (i) both advancing and receding contact angles of a droplet on a on smooth, homogeneous solid substrate can be calculated based on shape of disjoining/conjoining pressure isotherm, and (ii) both advancing and receding contact angles depend on the drop volume and are not unique characteristics of the liquid-solid system. The latter is different from advancing/receding contact angles in thin capillaries. It is shown also that the receding contact angle is much closer to the equilibrium contact angle than the advancing contact angle. The latter conclusion is unexpected and is in a contradiction with the commonly accepted view that the advancing contact angle can be taken as the first approximation for the equilibrium contact angle. The dependency of hysteresis contact angles on the drop volume has a direct experimental confirmation.

Fat fraction bias correction using T1 estimates and flip angle mapping.

PubMed

Yang, Issac Y; Cui, Yifan; Wiens, Curtis N; Wade, Trevor P; Friesen-Waldner, Lanette J; McKenzie, Charles A

2014-01-01

To develop a new method of reducing T1 bias in proton density fat fraction (PDFF) measured with iterative decomposition of water and fat with echo asymmetry and least-squares estimation (IDEAL). PDFF maps reconstructed from high flip angle IDEAL measurements were simulated and acquired from phantoms and volunteer L4 vertebrae. T1 bias was corrected using a priori T1 values for water and fat, both with and without flip angle correction. Signal-to-noise ratio (SNR) maps were used to measure precision of the reconstructed PDFF maps. PDFF measurements acquired using small flip angles were then compared to both sets of corrected large flip angle measurements for accuracy and precision. Simulations show similar results in PDFF error between small flip angle measurements and corrected large flip angle measurements as long as T1 estimates were within one standard deviation from the true value. Compared to low flip angle measurements, phantom and in vivo measurements demonstrate better precision and accuracy in PDFF measurements if images were acquired at a high flip angle, with T1 bias corrected using T1 estimates and flip angle mapping. T1 bias correction of large flip angle acquisitions using estimated T1 values with flip angle mapping yields fat fraction measurements of similar accuracy and superior precision compared to low flip angle acquisitions. Copyright © 2013 Wiley Periodicals, Inc.

Contact angle distribution of particles at fluid interfaces.

PubMed

Snoeyink, Craig; Barman, Sourav; Christopher, Gordon F

2015-01-27

Recent measurements have implied a distribution of interfacially adsorbed particles' contact angles; however, it has been impossible to measure statistically significant numbers for these contact angles noninvasively in situ. Using a new microscopy method that allows nanometer-scale resolution of particle's 3D positions on an interface, we have measured the contact angles for thousands of latex particles at an oil/water interface. Furthermore, these measurements are dynamic, allowing the observation of the particle contact angle with high temporal resolution, resulting in hundreds of thousands of individual contact angle measurements. The contact angle has been found to fit a normal distribution with a standard deviation of 19.3°, which is much larger than previously recorded. Furthermore, the technique used allows the effect of measurement error, constrained interfacial diffusion, and particle property variation on the contact angle distribution to be individually evaluated. Because of the ability to measure the contact angle noninvasively, the results provide previously unobtainable, unique data on the dynamics and distribution of the adsorbed particles' contact angle.

Behavior of Tilted Angle Shear Connectors

PubMed Central

Khorramian, Koosha; Maleki, Shervin; Shariati, Mahdi; Ramli Sulong, N. H.

2015-01-01

According to recent researches, angle shear connectors are appropriate to transfer longitudinal shear forces across the steel-concrete interface. Angle steel profile has been used in different positions as L-shaped or C-shaped shear connectors. The application of angle shear connectors in tilted positions is of interest in this study. This study investigates the behaviour of tilted-shaped angle shear connectors under monotonic loading using experimental push out tests. Eight push-out specimens are tested to investigate the effects of different angle parameters on the ultimate load capacity of connectors. Two different tilted angles of 112.5 and 135 degrees between the angle leg and steel beam are considered. In addition, angle sizes and lengths are varied. Two different failure modes were observed consisting of concrete crushing-splitting and connector fracture. By increasing the size of connector, the maximum load increased for most cases. In general, the 135 degrees tilted angle shear connectors have a higher strength and stiffness than the 112.5 degrees type. PMID:26642193

Behavior of Tilted Angle Shear Connectors.

PubMed

Khorramian, Koosha; Maleki, Shervin; Shariati, Mahdi; Ramli Sulong, N H

2015-01-01

According to recent researches, angle shear connectors are appropriate to transfer longitudinal shear forces across the steel-concrete interface. Angle steel profile has been used in different positions as L-shaped or C-shaped shear connectors. The application of angle shear connectors in tilted positions is of interest in this study. This study investigates the behaviour of tilted-shaped angle shear connectors under monotonic loading using experimental push out tests. Eight push-out specimens are tested to investigate the effects of different angle parameters on the ultimate load capacity of connectors. Two different tilted angles of 112.5 and 135 degrees between the angle leg and steel beam are considered. In addition, angle sizes and lengths are varied. Two different failure modes were observed consisting of concrete crushing-splitting and connector fracture. By increasing the size of connector, the maximum load increased for most cases. In general, the 135 degrees tilted angle shear connectors have a higher strength and stiffness than the 112.5 degrees type.

Assessment of narrow angles by gonioscopy, Van Herick method and anterior segment optical coherence tomography.

PubMed

Park, Seong Bae; Sung, Kyung Rim; Kang, Sung Yung; Jo, Jung Woo; Lee, Kyoung Sub; Kook, Michael S

2011-07-01

To evaluate anterior chamber (AC) angles using gonioscopy, Van Herick technique and anterior segment optical coherence tomography (AS-OCT). One hundred forty-eight consecutive subjects were enrolled. The agreement between any two of three diagnostic methods, gonioscopy, AS-OCT and Van Herick, was calculated in narrow-angle patients. The area under receiver-operating characteristic curves (AUC) for discriminating between narrow and open angles determined by gonioscopy was calculated in all participants for AS-OCT parameter angle opening distance (AOD), angle recess area, trabecular iris surface area and anterior chamber depth (ACD). As a subgroup analysis, capability of AS-OCT parameters for detecting angle closure defined by AS-OCT was assessed in narrow-angle patients. The agreement between the Van Herick method and gonioscopy in detecting angle closure was excellent in narrow angles (κ = 0.80, temporal; κ = 0.82, nasal). However, agreement between gonioscopy and AS-OCT and between the Van Herick method and AS-OCT was poor (κ = 0.11-0.16). Discrimination capability of AS-OCT parameters between open and narrow angles determined by gonioscopy was excellent for all AS-OCT parameters (AUC, temporal: AOD500 = 0.96, nasal: AOD500 = 0.99). The AUCs for detecting angle closure defined by AS-OCT image in narrow angle subjects was good for all AS-OCT parameters (AUC, 0.80-0.94) except for ACD (temporal: ACD = 0.70, nasal: ACD = 0.63). Assessment of narrow angles by gonioscopy and the Van Herick technique showed good agreement, but both measurements revealed poor agreement with AS-OCT. The angle closure detection capability of AS-OCT parameters was excellent; however, it was slightly lower in ACD.

Sun-view angle effects on reflectance factors of corn canopies

NASA Technical Reports Server (NTRS)

Ranson, K. J.; Daughtry, C. S. T.; Biehl, L. L.; Bauer, M. E.

1985-01-01

The effects of sun and view angles on reflectance factors of corn (Zea mays L.) canopies ranging from the six leaf stage to harvest maturity were studied on the Purdue University Agronomy Farm by a multiband radiometer. The two methods of acquiring spectral data, the truck system and the tower systrem, are described. The analysis of the spectral data is presented in three parts: solar angle effects on reflectance factors viewed at nadir; solar angle effects on reflectance factors viewed at a fixed sun angle; and both sun and view angles effect on reflectance factors. The analysis revealed that for nadir-viewed reflectance factors there is a strong solar angle dependence in all spectral bands for canopies with low leaf area index. Reflectance factors observed from the sun angle at different view azimuth angles showed that the position of the sensor relative to the sun is important in determining angular reflectance characteristics. For both sun and view angles, reflectance factors are maximized when the sensor view direction is towards the sun.

Apparent contact angle and contact angle hysteresis on liquid infused surfaces.

PubMed

Semprebon, Ciro; McHale, Glen; Kusumaatmaja, Halim

2016-12-21

We theoretically investigate the apparent contact angle and contact angle hysteresis of a droplet placed on a liquid infused surface. We show that the apparent contact angle is not uniquely defined by material parameters, but also has a dependence on the relative size between the droplet and its surrounding wetting ridge formed by the infusing liquid. We derive a closed form expression for the contact angle in the limit of vanishing wetting ridge, and compute the correction for small but finite ridge, which corresponds to an effective line tension term. We also predict contact angle hysteresis on liquid infused surfaces generated by the pinning of the contact lines by the surface corrugations. Our analytical expressions for both the apparent contact angle and contact angle hysteresis can be interpreted as 'weighted sums' between the contact angles of the infusing liquid relative to the droplet and surrounding gas phases, where the weighting coefficients are given by ratios of the fluid surface tensions.

Longitudinal Changes of Angle Configuration in Primary Angle-Closure Suspects

PubMed Central

Jiang, Yuzhen; Chang, Dolly S.; Zhu, Haogang; Khawaja, Anthony P.; Aung, Tin; Huang, Shengsong; Chen, Qianyun; Munoz, Beatriz; Grossi, Carlota M.

2015-01-01

Objective To determine longitudinal changes in angle configuration in the eyes of primary angle-closure suspects (PACS) treated by laser peripheral iridotomy (LPI) and in untreated fellow eyes. Design Longitudinal cohort study. Participants Primary angle-closure suspects aged 50 to 70 years were enrolled in a randomized, controlled clinical trial. Methods Each participant was treated by LPI in 1 randomly selected eye, with the fellow eye serving as a control. Angle width was assessed in a masked fashion using gonioscopy and anterior segment optical coherence tomography (AS-OCT) before and at 2 weeks, 6 months, and 18 months after LPI. Main Outcome Measures Angle width in degrees was calculated from Shaffer grades assessed under static gonioscopy. Angle configuration was also evaluated using angle opening distance (AOD250, AOD500, AOD750), trabecular-iris space area (TISA500, TISA750), and angle recess area (ARA) measured in AS-OCT images. Results No significant difference was found in baseline measures of angle configuration between treated and untreated eyes. At 2 weeks after LPI, the drainage angle on gonioscopy widened from a mean of 13.5° at baseline to a mean of 25.7° in treated eyes, which was also confirmed by significant increases in all AS-OCT angle width measures (P<0.001 for all variables). Between 2 weeks and 18 months after LPI, a significant decrease in angle width was observed over time in treated eyes (P<0.001 for all variables), although the change over the first 5.5 months was not statistically significant for angle width measured under gonioscopy (P = 0.18), AOD250 (P = 0.167) and ARA (P = 0.83). In untreated eyes, angle width consistently decreased across all follow-up visits after LPI, with a more rapid longitudinal decrease compared with treated eyes (P values for all variables ≤0.003). The annual rate of change in angle width was equivalent to 1.2°/year (95% confidence interval [CI], 0.8–1.6) in treated eyes and 1.6°/year (95% CI, 1.3–2.0) in untreated eyes (P<0.001). Conclusions Angle width of treated eyes increased markedly after LPI, remained stable for 6 months, and then decreased significantly by 18 months after LPI. Untreated eyes experienced a more consistent and rapid decrease in angle width over the same time period. PMID:24835757

Comparison of two spectral domain optical coherence tomography devices for angle-closure assessment.

PubMed

Quek, Desmond T; Narayanaswamy, Arun K; Tun, Tin A; Htoon, Hla M; Baskaran, Mani; Perera, Shamira A; Aung, Tin

2012-08-03

To compare two spectral domain optical coherence tomography (SD-OCT) devices for the identification of angle structures and the presence of angle closure. This was a prospective comparative study. Consecutive patients underwent gonioscopy and anterior segment imaging using two SD-OCT devices (iVue and Cirrus). Images were evaluated for the ability to detect angle structures such as Schwalbe's line (SL), trabecular meshwork (TM), Schlemm's canal (SC), and scleral spur (SS), and the presence of angle closure. Angle closure was defined as iris contact with the angle wall anterior to the SS on SD-OCT, and nonvisibility of the posterior TM on gonioscopy. Angle closure in an eye was defined as ≥two quadrants of closed angles. AC1 statistic was used to assess the agreement between devices. Of the 69 subjects studied (46.4% male, 84.1% Chinese, mean age 64.0 ± 10.5 years), 40 subjects (40 eyes, 58.0%) had angle closure on gonioscopy. The most identifiable structure on Cirrus SD-OCT was the SS (82.2%) and SL on iVue SD-OCT (74.5%). Angle closure was indeterminable in 14.5% and 50.7% of Cirrus and iVue scans (P < 0.001), respectively. Interdevice agreement for angle closure was moderately strong (AC1 = 0.67), but agreement with gonioscopy was only fair (AC1 = 0.35 and 0.50 for Cirrus and iVue, respectively). It was more difficult to determine angle closure status with iVue compared with Cirrus SD-OCT. There was fair agreement between both devices with gonioscopy for identifying angle closure.

The role of C2-C7 and O-C2 angle in the development of dysphagia after cervical spine surgery.

PubMed

Tian, Wei; Yu, Jie

2013-06-01

Dysphagia is a known complication of cervical surgery and may be prolonged or occasionally serious. A previous study showed that dysphagia after occipitocervical fusion was caused by oropharyngeal stenosis resulting from O-C2 (upper cervical lordosis) fixation in a flexed position. However, there have been few reports analyzing the association between the C2-C7 angle (middle-lower cervical lordosis) and postoperative dysphagia. The aim of this study was to analyze the relationship between cervical lordosis and the development of dysphagia after anterior and posterior cervical spine surgery (AC and PC). Three hundred fifty-four patients were reviewed in this retrospective clinical study, including 172 patients who underwent the AC procedure and 182 patients who had the PC procedure between June 2007 and May 2010. The presence and duration of postoperative dysphagia were recorded via face-to-face questioning or telephone interview performed at least 1 year after the procedure. Plain cervical radiographs before and after surgery were collected. The O-C2 angle and the C2-C7 angle were measured. Changes in the O-C2 angle and the C2-C7 angle were defined as dO-C2 angle = postoperative O-C2 angle - preoperative O-C2 angle and dC2-C7 angle = postoperative C2-C7 angle - preoperative C2-C7 angle. The association between postoperative dysphagia with dO-C2 angle and dC2-C7 angle was studied. Results showed that 12.8 % of AC and 9.4 % of PC patients reported dysphagia after cervical surgery. The dC2-C7 angle has considerable impact on postoperative dysphagia. When the dC2-C7 angle is greater than 5°, the chance of developing postoperative dysphagia is significantly greater. The dO-C2 angle, age, gender, BMI, operative time, blood loss, procedure type, revision surgery, most cephalic operative level, and number of operative levels did not significantly influence the incidence of postoperative dysphagia. No relationship was found between the dC2-C7 angle and the degree of dysphagia. We conclude that postoperative dysphagia is common after cervical surgery. The dC2-C7 angle may play an important role in the development of dysphagia in both anterior and posterior cervical spine surgery. Intraoperative measurement of the dC2-C7 angle is practical and essential in avoiding inadvertent postoperative dysphagia.

Angle Performance on Optima XE

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

David, Jonathan; Satoh, Shu

2011-01-07

Angle control on high energy implanters is important due to shrinking device dimensions, and sensitivity to channeling at high beam energies. On Optima XE, beam-to-wafer angles are controlled in both the horizontal and vertical directions. In the horizontal direction, the beam angle is measured through a series of narrow slits, and any angle adjustment is made by steering the beam with the corrector magnet. In the vertical direction, the beam angle is measured through a high aspect ratio mask, and any angle adjustment is made by slightly tilting the wafer platen during implant.Using a sensitive channeling condition, we were ablemore » to quantify the angle repeatability of Optima XE. By quantifying the sheet resistance sensitivity to both horizontal and vertical angle variation, the total angle variation was calculated as 0.04 deg. (1{sigma}). Implants were run over a five week period, with all of the wafers selected from a single boule, in order to control for any crystal cut variation.« less

Months between rejuvenation and volcanic eruption at Yellowstone caldera, Wyoming

USGS Publications Warehouse

Till, Christy B.; Vazquez, Jorge A.; Boyce, Jeremy W

2015-01-01

Rejuvenation of previously intruded silicic magma is an important process leading to effusive rhyolite, which is the most common product of volcanism at calderas with protracted histories of eruption and unrest such as Yellowstone, Long Valley, and Valles, USA. Although orders of magnitude smaller in volume than rare caldera-forming super-eruptions, these relatively frequent effusions of rhyolite are comparable to the largest eruptions of the 20th century and pose a considerable volcanic hazard. However, the physical pathway from rejuvenation to eruption of silicic magma is unclear particularly because the time between reheating of a subvolcanic intrusion and eruption is poorly quantified. This study uses geospeedometry of trace element profiles with nanometer resolution in sanidine crystals to reveal that Yellowstone’s most recent volcanic cycle began when remobilization of a near- or sub-solidus silicic magma occurred less than 10 months prior to eruption, following a 220,000 year period of volcanic repose. Our results reveal a geologically rapid timescale for rejuvenation and effusion of ~3 km3 of high-silica rhyolite lava even after protracted cooling of the subvolcanic system, which is consistent with recent physical modeling that predict a timescale of several years or less. Future renewal of rhyolitic volcanism at Yellowstone is likely to require an energetic intrusion of mafic or silicic magma into the shallow subvolcanic reservoir and could rapidly generate an eruptible rhyolite on timescales similar to those documented here.

Open segmental fracture of both bone forearm and dislocation of ipsilateral elbow with extruded middle segment radius

PubMed Central

Kumar, Pawan; Manjhi, Lal Bahadur; Rajak, Ramesh Lal

2013-01-01

Extruded middle segment of radius with open segmental fracture both bone forearm and dislocation of ipsilateral elbow is a rare injury. A 12-year-old child presented to us within 4 hours following fall from tree. The child's mother was carrying a 12-cm-long extruded soiled segment of radius. The extruded bone was thoroughly washed. The medullary cavity was properly syringed with antiseptic solution. The bone was autoclaved and put in the muscle plane of the distal forearm after debridement of the wound. After 5 days, a 2.5-mm K-wire was introduced by retrograde method into the proximal radius by passing through the extruded segment. Another 2.5-mm K-wire was passed in ulna. The limb was evaluated clinicoradiologically every 2 weeks. The wound was healed by primary intention. At 4 months, the reposed bone appeared less dense radiologically and K-wire seemed to be out of the bone. In the subsequent months, the roentgenograms show remodeling of the extruded fragment. After 20 weeks, the K-wires were removed (first ulnar and then radial). Complete union was achieved with full range of movement except loss of few degrees of extension of elbow and thumb. This case is reported to show a good outcome following successful incorporation of an extruded segment of radius in an open fracture. PMID:23798764

Tephra-fall deposits from the 1992 eruption of Crater Peak, Alaska: implications of clast textures for eruptive processes

USGS Publications Warehouse

Gardner, C.A.; Cashman, K.V.; Neal, C.A.

1998-01-01

The 1992 eruption of Crater Peak, Mount Spurr, Alaska, involved three subplinian tephra-producing events of similar volume and duration. The tephra consists of two dense juvenile clast types that are identified by color, one tan and one gray, of similar chemistry, mineral assemblage, and glass composition. In two of the eruptive events, the clast types are strongly stratified with tan clasts dominating the basal two thirds of the deposits and gray clasts the upper one third. Tan clasts have average densities between 1.5 and 1.7 g/cc and vesicularities (phenocryst free) of approximately 42%. Gray clasts have average densities between 2.1 and 2.3 g/cc, and vesicularities of approximately 20%; both contain abundant microlites. Average maximum plagioclase microlite lengths (13-15 ??m) in gray clasts in the upper layer are similar regardless of eruptive event (and therefore the repose time between them) and are larger than average maximum plagioclase microlite lengths (9-11 ???m) in the tan clasts in the lower layer. This suggests that microlite growth is a response to eruptive processes and not to magma reservoir heterogeneity or dynamics. Furthermore, we suggest that the low vesicularities of the clasts are due to syneruptive magmatic degassing resulting in microlitic growth prior to fragmentation and not to quenching of clasts by external groundwater.

Historical unrest at large calderas of the world

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

Newhall, C.A.; Dzurisin, D.

1989-09-01

This is a remarkable reference for researchers interested in volcanic hazards and silicic volcanism. Because of long repose and often obscure shapes and large size calderas are a volcanic type less obvious and less well studied. Because they represent potentially highly dangerous and highly explosive volcanos which could have large-scale and even global impact when they erupt, it is very important to understand their behavior. This new volume represents an extensive effort at compiling real observations at earth's calderas. The authors manage to incorporate a very impressive list of original references that go far beyond standard volcanological literature and alsomore » often extend back many centuries to include the perspective of longer historic time at some calderas. If volcanologists are serious about eruption forecasting, they must be willing to dig out and absorb the lessons of historic observations as well as design instruments and make good measurements. There is an initial introductory chapter of 27 pages which attempts to lead the way to interpretation of various patterns of caldera unrest, based on synthesis of the various individual cases. The meat of the volumes is in sections on the individual calderas, enriched with many maps and figures documenting the caldera unrest. A valuable asset of the compilation is its broad scope, which incorporates the activity of related or possibly related cones, domes, solfataras, etc., with the parent ( ) caldera.« less

Computer programs for calculation of sting pitch and roll angles required to obtain angles of attack and sideslip on wind tunnel models

NASA Technical Reports Server (NTRS)

Peterson, John B., Jr.

1988-01-01

Two programs have been developed to calculate the pitch and roll angles of a wind-tunnel sting drive system that will position a model at the desired angle of attack and and angle of sideslip in the wind tunnel. These programs account for the effects of sting offset angles, sting bending angles and wind-tunnel stream flow angles. In addition, the second program incorporates inputs from on-board accelerometers that measure model pitch and roll with respect to gravity. The programs are presented in the report and a description of the numerical operation of the programs with a definition of the variables used in the programs is given.

Longitudinal changes of angle configuration in primary angle-closure suspects: the Zhongshan Angle-Closure Prevention Trial.

PubMed

Jiang, Yuzhen; Chang, Dolly S; Zhu, Haogang; Khawaja, Anthony P; Aung, Tin; Huang, Shengsong; Chen, Qianyun; Munoz, Beatriz; Grossi, Carlota M; He, Mingguang; Friedman, David S; Foster, Paul J

2014-09-01

To determine longitudinal changes in angle configuration in the eyes of primary angle-closure suspects (PACS) treated by laser peripheral iridotomy (LPI) and in untreated fellow eyes. Longitudinal cohort study. Primary angle-closure suspects aged 50 to 70 years were enrolled in a randomized, controlled clinical trial. Each participant was treated by LPI in 1 randomly selected eye, with the fellow eye serving as a control. Angle width was assessed in a masked fashion using gonioscopy and anterior segment optical coherence tomography (AS-OCT) before and at 2 weeks, 6 months, and 18 months after LPI. Angle width in degrees was calculated from Shaffer grades assessed under static gonioscopy. Angle configuration was also evaluated using angle opening distance (AOD250, AOD500, AOD750), trabecular-iris space area (TISA500, TISA750), and angle recess area (ARA) measured in AS-OCT images. No significant difference was found in baseline measures of angle configuration between treated and untreated eyes. At 2 weeks after LPI, the drainage angle on gonioscopy widened from a mean of 13.5° at baseline to a mean of 25.7° in treated eyes, which was also confirmed by significant increases in all AS-OCT angle width measures (P<0.001 for all variables). Between 2 weeks and 18 months after LPI, a significant decrease in angle width was observed over time in treated eyes (P<0.001 for all variables), although the change over the first 5.5 months was not statistically significant for angle width measured under gonioscopy (P = 0.18), AOD250 (P = 0.167) and ARA (P = 0.83). In untreated eyes, angle width consistently decreased across all follow-up visits after LPI, with a more rapid longitudinal decrease compared with treated eyes (P values for all variables ≤0.003). The annual rate of change in angle width was equivalent to 1.2°/year (95% confidence interval [CI], 0.8-1.6) in treated eyes and 1.6°/year (95% CI, 1.3-2.0) in untreated eyes (P<0.001). Angle width of treated eyes increased markedly after LPI, remained stable for 6 months, and then decreased significantly by 18 months after LPI. Untreated eyes experienced a more consistent and rapid decrease in angle width over the same time period. Copyright © 2014 American Academy of Ophthalmology. Published by Elsevier Inc. All rights reserved.

Apparatus and method for variable angle slant hole collimator

DOEpatents

Lee, Seung Joon; Kross, Brian J.; McKisson, John E.

2017-07-18

A variable angle slant hole (VASH) collimator for providing collimation of high energy photons such as gamma rays during radiological imaging of humans. The VASH collimator includes a stack of multiple collimator leaves and a means of quickly aligning each leaf to provide various projection angles. Rather than rotate the detector around the subject, the VASH collimator enables the detector to remain stationary while the projection angle of the collimator is varied for tomographic acquisition. High collimator efficiency is achieved by maintaining the leaves in accurate alignment through the various projection angles. Individual leaves include unique angled cuts to maintain a precise target collimation angle. Matching wedge blocks driven by two actuators with twin-lead screws accurately position each leaf in the stack resulting in the precise target collimation angle. A computer interface with the actuators enables precise control of the projection angle of the collimator.

Bidirectional measurements of surface reflectance for view angle corrections of oblique imagery

NASA Technical Reports Server (NTRS)

Jackson, R. D.; Teillet, P. M.; Slater, P. N.; Fedosejevs, G.; Jasinski, Michael F.

1990-01-01

An apparatus for acquiring bidirectional reflectance-factor data was constructed and used over four surface types. Data sets were obtained over a headed wheat canopy, bare soil having several different roughness conditions, playa (dry lake bed), and gypsum sand. Results are presented in terms of relative bidirectional reflectance factors (BRFs) as a function of view angle at a number of solar zenith angles, nadir BRFs as a function of solar zenith angles, and, for wheat, vegetation indices as related to view and solar zenith angles. The wheat canopy exhibited the largest BRF changes with view angle. BRFs for the red and the NIR bands measured over wheat did not have the same relationship with view angle. NIR/Red ratios calculated from nadir BRFs changed by nearly a factor of 2 when the solar zenith angle changed from 20 to 50 degs. BRF versus view angle relationships were similar for soils having smooth and intermediate rough surfaces but were considerably different for the roughest surface. Nadir BRF versus solar-zenith angle relationships were distinctly different for the three soil roughness levels. Of the various surfaces, BRFs for gypsum sand changed the least with view angle (10 percent at 30 degs).

A gallery approach for off-angle iris recognition

NASA Astrophysics Data System (ADS)

Karakaya, Mahmut; Yoldash, Rashiduddin; Boehnen, Christopher

2015-05-01

It has been proven that hamming distance score between frontal and off-angle iris images of same eye differs in iris recognition system. The distinction of hamming distance score is caused by many factors such as image acquisition angle, occlusion, pupil dilation, and limbus effect. In this paper, we first study the effect of the angle variations between iris plane and the image acquisition systems. We present how hamming distance changes for different off-angle iris images even if they are coming from the same iris. We observe that increment in acquisition angle of compared iris images causes the increment in hamming distance. Second, we propose a new technique in off-angle iris recognition system that includes creating a gallery of different off-angle iris images (such as, 0, 10, 20, 30, 40, and 50 degrees) and comparing each probe image with these gallery images. We will show the accuracy of the gallery approach for off-angle iris recognition.

Can a surgeon drill accurately at a specified angle?

PubMed Central

Brioschi, Valentina; Cook, Jodie; Arthurs, Gareth I

2016-01-01

Objectives To investigate whether a surgeon can drill accurately a specified angle and whether surgeon experience, task repetition, drill bit size and perceived difficulty influence drilling angle accuracy. Methods The sample population consisted of final-year students (n=25), non-specialist veterinarians (n=22) and board-certified orthopaedic surgeons (n=8). Each participant drilled a hole twice in a horizontal oak plank at 30°, 45°, 60°, 80°, 85° and 90° angles with either a 2.5  or a 3.5 mm drill bit. Participants then rated the perceived difficulty to drill each angle. The true angle of each hole was measured using a digital goniometer. Results Greater drilling accuracy was achieved at angles closer to 90°. An error of ≤±4° was achieved by 84.5 per cent of participants drilling a 90° angle compared with approximately 20 per cent of participants drilling a 30–45° angle. There was no effect of surgeon experience, task repetition or drill bit size on the mean error for intended versus achieved angle. Increased perception of difficulty was associated with the more acute angles and decreased accuracy, but not experience level. Clinical significance This study shows that surgeon ability to drill accurately (within ±4° error) is limited, particularly at angles ≤60°. In situations where drill angle is critical, use of computer-assisted navigation or custom-made drill guides may be preferable. PMID:27547423

Variations in trace metal and halogen ratios in magmatic gases through an eruptive cycle of the Pu'u O'o vent, Kilauea, Hawaii: July-August 1985

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

Miller, T.L.; Zoller, W.H.; Crowe, B.M.

1990-08-10

Particle and gas samples were obtained before and after eruptive episode 35 in July and August 1985 at the fuming Pu'u O'o vent, Kilauea volcano, Hawaii. The sampling system employed consisted of a particle filter followed by four {sup 7}LiOH treated filters to collect acidic gases. The filters were analyzed using instrumental neutron activation analysis (INAA). The results indicate that Br/Cl and Re/Cl ratios do not fluctuate through an eruption cycle but the F/Cl, F/Br and metal/Cl ratios (In and Cd) do change through the cycle. An inverse relationship between F/Cl and metal/Cl was observed. The changes are probably duemore » to influxes of relatively undegassed magma during the repose period releasing fume with lower F/Cl, F/BR and higher metal/Cl ratios. As the magma in the Pu'u O'o conduit gradually degasses either before or several days after an eruptive episode, F/Cl and F/Br ratios increase and the metal/Cl ratios decrease. One sample collected on July 24, two days before eruptive episode 35, did not follow this general trend. This can be explained by a gas pulse from a deeper, less degassed portion of magma making its way to the top of the conduit.« less

"Variations in trace metal and halogen ratios in magmatic gases through an eruptive. Cycle of the Pu'u O'o Vent, Kilauea, Hawaii: July-August 1985""

NASA Astrophysics Data System (ADS)

Miller, Theresa L.; Zoller, William H.; Crowe, Bruce M.; Finnegan, David L.

1990-08-01

Particle and gas samples were obtained before and after eruptive episode 35 in July and August 1985 at the fuming Pu'u O'o vent, Kilauea volcano, Hawaii. The sampling system employed consisted of a particle filter followed by four 7LiOH treated filters to collect acidic gases. The filters were analyzed using instrumental neutron activation analysis (INAA). The results indicate that Br/Cl and Re/Cl ratios do not fluctuate through an eruption cycle but the F/Cl, F/Br and metal/Cl ratios (In and Cd) do change through the cycle. An inverse relationship between F/Cl and metal/Cl was observed. The changes are probably due to influxes of relatively undegassed magma during the repose period releasing fume with lower F/Cl, F/Br and higher metal/Cl ratios. As the magma in the Pu'u O'o conduit gradually degasses either before or several days after an eruptive episode, F/Cl and F/Br ratios increase and the metal/Cl ratios decrease. One sample collected on July 24, two days before eruptive episode 35, did not follow this general trend. This can be explained by a gas pulse from a deeper, less degassed portion of magma making its way to the top of the conduit.

An Experimental Study on the Iso-Content-Based Angle Similarity Measure.

ERIC Educational Resources Information Center

Zhang, Jin; Rasmussen, Edie M.

2002-01-01

Retrieval performance of the iso-content-based angle similarity measure within the angle, distance, conjunction, disjunction, and ellipse retrieval models is compared with retrieval performance of the distance similarity measure and the angle similarity measure. Results show the iso-content-based angle similarity measure achieves satisfactory…

View angle effect in LANDSAT imagery

NASA Technical Reports Server (NTRS)

Kaneko, T.; Engvall, J. L.

1977-01-01

The view angle effect in LANDSAT 2 imagery was investigated. The LANDSAT multispectral scanner scans over a range of view angles of -5.78 to 5.78 degrees. The view angle effect, which is caused by differing view angles, could be studied by comparing data collected at different view angles over a fixed location at a fixed time. Since such LANDSAT data is not available, consecutive day acquisition data were used as a substitute: they were collected over the same geographical location, acquired 24 hours apart, with a view angle change of 7 to 8 degrees at a latitude of 35 to 45 degrees. It is shown that there is approximately a 5% reduction in the average sensor response on the second-day acquisitions as compared with the first-day acquisitions, and that the view angle effect differs field to field and crop to crop. On false infrared color pictures the view angle effect causes changes primarily in brightness and to a lesser degree in color (hue and saturation). An implication is that caution must be taken when images with different view angles are combined for classification and a signature extension technique needs to take the view angle effect into account.

Optimum take-off angle in the long jump.

PubMed

Linthorne, Nicholas P; Guzman, Maurice S; Bridgett, Lisa A

2005-07-01

In this study, we found that the optimum take-off angle for a long jumper may be predicted by combining the equation for the range of a projectile in free flight with the measured relations between take-off speed, take-off height and take-off angle for the athlete. The prediction method was evaluated using video measurements of three experienced male long jumpers who performed maximum-effort jumps over a wide range of take-off angles. To produce low take-off angles the athletes used a long and fast run-up, whereas higher take-off angles were produced using a progressively shorter and slower run-up. For all three athletes, the take-off speed decreased and the take-off height increased as the athlete jumped with a higher take-off angle. The calculated optimum take-off angles were in good agreement with the athletes' competition take-off angles.

[Clinical significance of Q-angle under different conditions in recurrent patellar dislocation].

PubMed

Wang, Zhijie; Chen, You; Li, Anping; Long, Yi

2014-01-01

To investigate the clinical significance of Q-angle measuring under different conditions in female recurrent patellar dislocation female patients. Between August 2012 and March 2013, 10 female patients (11 knees) with recurrent patellar dislocation were collected as trial group; 20 female patients (20 knees) with simple meniscus injury were collected as control group at the same time. Q-angle was measured in extension, 30 degrees flexion, 30 degrees flexion with manual correction, and surgical correction in the trial group, and only in extension and 30 degrees flexion in the control group. Then the difference value of Q-angle between extension and 30 degrees flexion (Q-angle in extension subtracts Q-angle in 30 flexion) were calculated. Independent sample t-test was used to analyze Q-angle degrees in extension, 30 degrees flexion, and the changed degrees of 2 groups. The Q-angle between manual correction and surgical correction of the trial group was analyzed by paired t-test. The Q-angle in extension, Q-angle in 30 degrees flexion, and difference value of Q-angle between extension and 30 degrees flexion were (17.2 +/- 3.6), (14.3 +/- 3.0), and (2.9 +/- 1.9) degrees in the trial group and were (15.2 +/- 3.4), (14.4 +/- 3.5), and (0.8 +/- 1.7) degrees in the control group. No significant difference was found in Q-angle of extension or Q-angle of 30 degrees flexion between 2 groups (P > 0.05), but the difference value of Q-angle between extension and 30 degrees flexion in the trial group was significantly larger than that in the control group (t = 3.253, P = 0.003). The Q-angle in 30 degrees flexion with manual correction and surgical correction in the trial group was (19.8 +/- 3.4) degrees and (18.9 +/- 3.8) degrees respectively, showing no significant difference (t = 2.193, P = 0.053). When a female patient's Q-angle in 30 degrees flexion knee changes obviously compared with Q-angle in extension position, recurrent patellar dislocation should be considered. For female patients with recurrent patellar dislocation, the preoperative Q-angle in 30 degrees flexion with manual correction should be measured, which can help increasing the accuracy of evaluation whether rearrangement should be performed.

Bilateral mandibular angle fractures: clinical considerations.

PubMed

Boffano, Paolo; Roccia, Fabio

2010-03-01

The mandibular angle is a frequent site of fracture. It is a weak zone that is more exposed to fractures than other areas of the mandibular bone. The presence of incompletely erupted third molars is associated with a further increased risk of angle fractures. Our objective was to evaluate and discuss the surgical outcomes of a group of patients with bilateral mandibular angle fractures.In our study, patients with bilateral mandibular angle fractures surgically treated from January 1, 2001, to June 30, 2009, at the Division of Maxillofacial Surgery of the University of Turin were retrospectively analyzed. A combined transbuccal and intraoral approach or an intraoral approach only was adopted.Eight patients (7 men and 1 woman) underwent surgery for bilateral mandibular angle fractures. Good to satisfactory reduction of the fractures was obtained with both surgical techniques. Good to fair restored occlusion was observed postoperatively in all patients.Successful treatment of bilateral mandibular angle fractures may be achieved via different techniques. Superficially impacted third molars seem to be associated with an increased risk of angle fractures. Bilateral angle fractures are an ideal model to study the biomechanical pathogenesis of angle fractures.

Research of working pulsation in closed angle based on rotating-sleeve distributing-flow system

NASA Astrophysics Data System (ADS)

Zhang, Yanjun; Zhang, Hongxin; Zhao, Qinghai; Jiang, Xiaotian; Cheng, Qianchang

2017-08-01

In order to reduce negative effects including hydraulic impact, noise and mechanical vibration, compression and expansion of piston pump in closed volume are used to optimize the angle between valve port and chamber. In addition, the mathematical model about pressurization and depressurization in pump chamber are analyzed based on distributing-flow characteristic, and it is necessary to use simulation software Fluent to simulate the distributing-flow fluid model so as to select the most suitable closed angle. As a result, when compression angle is 3°, the angle is closest to theoretical analysis and has the minimum influence on flow and pump pressure characteristic. Meanwhile, cavitation phenomenon appears in pump chamber in different closed angle on different degrees. Besides the flow pulsation is increasingly smaller with increasing expansion angle. Thus when expansion angle is 2°, the angle is more suitable for distributing-flow system.

Automated localization of costophrenic recesses and costophrenic angle measurement on frontal chest radiographs

NASA Astrophysics Data System (ADS)

Maduskar, Pragnya; Hogeweg, Laurens; Philipsen, Rick; van Ginneken, Bram

2013-03-01

Computer aided detection (CAD) of tuberculosis (TB) on chest radiographs (CXR) is difficult because the disease has varied manifestations, like opacification, hilar elevation, and pleural effusions. We have developed a CAD research prototype for TB (CAD4TB v1.08, Diagnostic Image Analysis Group, Nijmegen, The Netherlands) which is trained to detect textural abnormalities inside unobscured lung fields. If the only abnormality visible on a CXR would be a blunt costophrenic angle, caused by pleural fluid in the costophrenic recess, this is likely to be missed by texture analysis in the lung fields. The goal of this work is therefore to detect the presence of blunt costophrenic (CP) angles caused by pleural effusion on chest radiographs. The CP angle is the angle formed by the hemidiaphragm and the chest wall. We define the intersection point of both as the CP angle point. We first detect the CP angle point automatically from a lung field segmentation by finding the foreground pixel of each lung with maximum y location. Patches are extracted around the CP angle point and boundary tracing is performed to detect 10 consecutive pixels along the hemidiaphragm and the chest wall and derive the CP angle from these. We evaluate the method on a data set of 250 normal CXRs, 200 CXRs with only one or two blunt CP angles and 200 CXRs with one or two blunt CP angles but also other abnormalities. For these three groups, the CP angle location and angle measurements were accurate in 91%, 88%, and 92% of all the cases, respectively. The average CP angles for the three groups are indeed different with 71.6° +/- 22.9, 87.5° +/- 25.7, and 87.7° +/- 25.3, respectively.

Measurement of Knee Rotation Angles Using a Smartphone Application: An Experimental Study of Porcine Knees.

PubMed

Kim, Hee-June; Lee, Hyun-Joo; Shin, Ji-Yeon; Choi, Young-Seo; Kyung, Hee-Soo

2017-12-01

This study evaluated the efficacy of a smartphone application in the measurement of rotation angles in porcine knees. Two K-wires were fixated to the femoral condyle and anterior tibial crest of 10 porcine legs. The angle created between the K-wires with an external rotation force applied was measured on a photograph and defined as the true angle. The same force was applied to the legs placed on a splint with a smartphone attached to the plantar side. The angle presented on a smartphone application was determined as the measured angle. The differences between the true and measured angles in 30° and 90° knee flexion and differences in measured angles depending on the status of the popliteus tendon were compared. In the intact knees, the mean true angles in 30° and 90° flexion were 20.5°±1.4° and 19.1°±1.3°, respectively, and the mean measured angles in 30° and 90° flexion were 21.1°±0.9° and 18.6°±1.6°, respectively. When the popliteus tendon was cut, the mean true angles in 30° and 90° flexion were 31.4°±1.1° and 38.5°±2.5°, respectively, and the mean measured angles in 30° and 90° flexion were 31.8°±1.2° and 39.2°±2.8°, respectively. The differences between the true and measured angles were not significant. The measured angle increased by more than 10° after cutting of the popliteus tendon in both 30° and 90° flexion. Using a smartphone application could be a good method of measuring knee rotation.

Mercury - the hollow planet

NASA Astrophysics Data System (ADS)

Rothery, D. A.

2012-04-01

Mercury is turning out to be a planet characterized by various kinds of endogenous hole (discounting impact craters), which are compared here. These include volcanic vents and collapse features on horizontal scales of tens of km, and smaller scale depressions ('hollows') associated with bright crater-floor deposits (BCFD). The BCFD hollows are tens of metres deep and kilometres or less across and are characteristically flat-floored, with steep, scalloped walls. Their form suggests that they most likely result from removal of surface material by some kind of mass-wasting process, probably associated with volume-loss caused by removal (via sublimation?) of a volatile component. These do not appear to be primarily a result of undermining. Determining the composition of the high-albedo bluish surface coating in BCFDs will be a key goal for BepiColombo instruments such as MIXS (Mercury Imaging Xray Spectrometer). In contrast, collapse features are non-circular rimless pits, typically on crater floors (pit-floor craters), whose morphology suggests collapse into void spaces left by magma withdrawal. This could be by drainage of either erupted lava (or impact melt) or of shallowly-intruded magma. Unlike the much smaller-scale BCFD hollows, these 'collapse pit' features tend to lack extensive flat floors and instead tend to be close to triangular in cross-section with inward slopes near to the critical angle of repose. The different scale and morphology of BCFD hollows and collapse pits argues for quite different modes of origin. However, BCFD hollows adjacent to and within the collapse pit inside Scarlatti crater suggest that the volatile material whose loss was responsible for the growth of the hollows may have been emplaced in association with the magma whose drainage caused the main collapse. Another kind of volcanic collapse can be seen within a 25 km-wide volcanic vent outside the southern rim of the Caloris basin (22.5° N, 146.1° E), on a 28 m/pixel MDIS NAC image from orbit. Although the vent itself may have been excavated partly by explosive volcanism, the most recent event is collapse of a 7 km wide zone in the south centre of the vent. The sharpness of features within this (unmuted either by regolith-forming processes or by fall of volcanic ejecta) suggests that this collapse considerably post-dates the rest of the vent interior. It could reflect a late-stage minor 'throat clearing' explosive eruption, but (in the absence of evidence of associated volcanic ejecta) more likely reflects collapse into a void within the volcanic conduit, itself a result of magma-drainage. A class of 'hole' that is so far conspicuous by its absence on Mercury is sinuous rilles (as opposed to much straighter tectonic grabens) or aligned skylights representing collapsed or partly-collapsed drained lava tubes. Tube-fed flows are to be expected during emplacement of volcanic plains, and it will be surprising if no examples are revealed on MESSENGER and BepiColombo high-resolution images.

Recommandations sur l’examen pelvien de dépistage systématique

PubMed Central

Tonelli, Marcello; Gorber, Sarah Connor; Moore, Ainsley; Thombs, Brett D.

2016-01-01

Résumé Objectif Examiner les lignes directrices de 2014 de l’American College of Physicians (ACP) en matière d’examens pelviens de dépistage du cancer (autre que du col), des maladies inflammatoires pelviennes ou d’autres affections gynécologiques bénignes afin de déterminer si les lignes directrices de l’ACP en matière d’examens pelviens systématiques sont conformes aux normes établies par le Groupe d’étude canadien sur les soins de santé préventifs (GECSSP) et peuvent être adaptées ou adoptées. Méthodologie La méthode SNAP-IT (Smooth National Adaptation and Presentation of Guidelines to Improve Thrombosis Treatment) a servi à déterminer si les lignes directrices de l’ACP étaient conformes aux normes du GECSSP et pouvaient être adaptées ou adoptées. Recommandations Le GECSSP recommande de ne pas effectuer un examen pelvien de dépistage des cancers non cervicaux, des maladies inflammatoires pelviennes ou d’autres affections gynécologiques chez les femmes asymptomatiques. Il s’agit d’une forte recommandation reposant sur des données probantes de qualité modérée. Conclusion Le GECSSP adopte la recommandation en matière d’examen pelvien de dépistage, comme publiée par l’ACP en 2014.

Comparison between medial rectus pulley fixation and augmented recession in children with convergence excess and variable-angle infantile esotropia.

PubMed

Fouad, Heba M; Abdelhakim, Mohamad A; Awadein, Ahmed; Elhilali, Hala

2016-10-01

To compare the outcomes of medial rectus (MR) muscle pulley fixation and augmented recession in children with convergence excess esotropia and variable-angle infantile esotropia. This was a prospective randomized interventional study in which children with convergence excess esotropia or variable-angle infantile esotropia were randomly allocated to either augmented MR muscle recession (augmented group) or MR muscle pulley posterior fixation (pulley group). In convergence excess, the MR recession was based on the average of distance and near angles of deviation with distance correction in the augmented group, and on the distance angle of deviation in the pulley group. In variable-angle infantile esotropia, the MR recession was based on the average of the largest and smallest angles in the augmented group and on the smallest angle in the pulley group. Pre- and postoperative ductions, versions, pattern strabismus, smallest and largest angles of deviation, and angle disparity were analyzed. Surgery was performed on 60 patients: 30 underwent bilateral augmented MR recession, and 30 underwent bilateral MR recession with pulley fixation. The success rate was statistically significantly higher (P = 0.037) in the pulley group (70%) than in the augmented group (40%). The postoperative smallest and largest angles and the angle disparity were statistically significantly lower in the pulley group than the augmented group (P < 0.01). Medial rectus muscle pulley fixation is a useful surgical step for addressing marked variability of the angle in variable angle esotropia and convergence excess esotropia. Copyright © 2016 American Association for Pediatric Ophthalmology and Strabismus. Published by Elsevier Inc. All rights reserved.

Determination of the Basic Friction Angle of Rock Surfaces by Tilt Tests

NASA Astrophysics Data System (ADS)

Jang, Hyun-Sic; Zhang, Qing-Zhao; Kang, Seong-Seung; Jang, Bo-An

2018-04-01

Samples of Hwangdeung granite from Korea and Berea sandstone from USA, both containing sliding planes, were prepared by saw-cutting or polishing using either #100 or #600 grinding powders. Their basic friction angles were measured by direct shear testing, triaxial compression testing, and tilt testing. The direct shear tests and triaxial compression tests on the saw-cut, #100, and #600 surfaces indicated that the most reliable results were obtained from the #100 surface: basic friction angle of 29.4° for granite and 34.1° for sandstone. To examine the effect of surface conditions on the friction angle in tilt tests, the sliding angles were measured 50 times with two surface conditions (surfaces cleaned and not cleaned after each measurement). The initial sliding angles were high regardless of rock type and surface conditions and decreased exponentially as measurements continued. The characteristics of the sliding angles, differences between tilt tests, and dispersion between measurements in each test indicated that #100 surface produced the most reliable basic friction angle measurement. Without cleaning the surfaces, the average angles for granite (32 measurements) and sandstone (23 measurements) were similar to the basic friction angle. When 20-50 measurements without cleaning were averaged, the basic friction angle was within ± 2° for granite and ± 3° for sandstone. Sliding angles using five different tilting speeds were measured but the average was similar, indicating that tilting speed (between 0.2° and 1.6°/s) has little effect on the sliding angle. Sliding angles using four different sample sizes were measured with the best results obtained for samples larger than 8 × 8 cm.

Forefoot angle at initial contact determines the amplitude of forefoot and rearfoot eversion during running.

PubMed

Monaghan, Gail M; Hsu, Wen-Hao; Lewis, Cara L; Saltzman, Elliot; Hamill, Joseph; Holt, Kenneth G

2014-09-01

Clinically, foot structures are assessed intrinsically - relation of forefoot to rearfoot and rearfoot to leg. We have argued that, from a biomechanical perspective, the interaction of the foot with the ground may influence forces and torques that are propagated through the lower extremity. We proposed that a more appropriate measure is an extrinsic one that may predict the angle the foot makes with ground at contact. The purposes of this study were to determine if the proposed measure predicts contact angles of the forefoot and rearfoot and assess if the magnitude of those angles influences amplitude and duration of foot eversion during running. With the individual in prone, extrinsic clinical forefoot and rearfoot angles were measured relative to the caudal edge of the examination table. Participants ran over ground while frontal plane forefoot and rearfoot contact angles, forefoot and rearfoot eversion amplitude and duration were measured. Participants were grouped twice, once based on forefoot contact inversion angle (moderatemedian) and once based on rearfoot contact inversion angle (moderatemedian). The forefoot and rearfoot extrinsic clinical angles predicted, respectively, the forefoot and rearfoot angles at ground contact. Large forefoot contact angles were associated with greater amplitudes (but not durations) of forefoot and rearfoot eversion during stance. Rearfoot contact angles, however, were associated with neither amplitudes nor durations of forefoot and rearfoot eversion. Possible mechanisms for the increased risk of running injuries associated with large forefoot angles are discussed. Copyright © 2014 Elsevier Ltd. All rights reserved.

Definition, transformation-formulae and measurements of tipvane angles

NASA Astrophysics Data System (ADS)

Bruining, A.

1987-10-01

The theoretical background of different angle systems used to define tipvane attitude in 3-D space is outlined. Different Euler equations are used for the various, wind tunnel, towing tank, and full scale tipvane models. The influence of rotor blade flapping angle on tipvane angles is described. The tipvane attitude measuring method is outlined in relationship to the Euler angle system. Side effects on the angle of attack of the tipvane due to rotation, translation, and curving of the tipvane are described.

Assessment of circumferential angle-closure by the iris-trabecular contact index with swept-source optical coherence tomography.

PubMed

Baskaran, Mani; Ho, Sue-Wei; Tun, Tin A; How, Alicia C; Perera, Shamira A; Friedman, David S; Aung, Tin

2013-11-01

To evaluate the diagnostic performance of the iris-trabecular contact (ITC) index, a measure of the degree of angle-closure, using swept-source optical coherence tomography (SSOCT, CASIA SS-1000, Tomey Corporation, Nagoya, Japan) in comparison with gonioscopy. Prospective observational study. A total of 108 normal subjects and 32 subjects with angle-closure. The SSOCT 3-dimensional angle scans, which obtain radial scans for the entire circumference of the angle, were performed under dark conditions and analyzed using customized software by a single examiner masked to the subjects' clinical details. The ITC index was calculated as a percentage of the angle that was closed on SSOCT images. First-order agreement coefficient (AC1) statistics and area under the receiver operating characteristic curve (AUC) analyses were performed for angle-closure on the basis of the ITC index in comparison with gonioscopy. Angle-closure on gonioscopy was defined as nonvisibility of posterior trabecular meshwork for at least 2 quadrants. Agreement of the ITC index with gonioscopically defined angle-closure was assessed using the AC1 statistic. Study subjects were predominantly Chinese (95.7%) and female (70.7%), with a mean age of 59.2 (standard deviation, 8.9) years. The median ITC index was 15.24% for gonioscopically open-angle eyes (n = 108) and 48.5% for closed-angle eyes (n = 32) (P = 0.0001). The agreement for angle-closure based on ITC index cutoffs (>35% and ≥50%) and gonioscopic angle-closure was 0.699 and 0.718, respectively. The AUC for angle-closure detection using the ITC index was 0.83 (95% confidence interval, 0.76-0.89), with an ITC index >35% having a sensitivity of 71.9% and specificity of 84.3%. The ITC index is a summary measure of the circumferential extent of angle-closure as imaged with SSOCT. The index had moderate agreement and good diagnostic performance for angle-closure with gonioscopy as the reference standard. Copyright © 2013 American Academy of Ophthalmology. Published by Elsevier Inc. All rights reserved.

The hallux valgus angle of the margo medialis pedis as an alternative to the measurement of the metatarsophalangeal hallux valgus angle.

PubMed

Klein, Christian; Kinz, Wieland; Zembsch, Alexander; Groll-Knapp, Elisabeth; Kundi, Michael

2014-04-21

Currently, the metatarsophalangeal angle (hallux valgus angle) is measured based on radiographic images. However, using X-ray examinations for epidemiological or screening purposes would be unethical, especially in children. For this reason it is discussed to measure the hallux valgus angle of the margo medialis pedis (medial border of the foot) documented on foot outline drawings or foot scans. As a first step on the way to prove the validity of those approaches this study assesses the hallux valgus angle measured on the margo medialis pedis based on the same x-ray pictures as the metatarsophalangeal hallux valgus. Radiographic images of the foot were obtained from patients with symptomatic hallux valgus malformation. Twelve sets of contact copies of the 63 originals were made, and were marked and measured according to three different methods, each one performed by two observers and with two repeated measurements. Thus, data sets from 756 individual assessments were entered into the multifactorial statistical analysis.Comparisons were made between the angle of the margo medialis pedis and the metatarsophalangeal angle, which was determined by two different methods. To determine the inter- and intraobserver reliability of the different methods, each assessment was conducted by two independent experts and repeated after a period of several weeks. The correlations between the hallux valgus angles determined by the three different methods were all above r=0.89 (p<0.001) and thus highly significant. The values obtained by measuring the margo medialis pedis angle, however, were on average 4.8 degrees smaller than the metatarsophalangeal angles. No significant differences were found between the observers. No systematic deviations for any observer between repeated measurements were detected. Measurements of the radiographic hallux angle of the margo medialis pedis are reliable and show high correlation with the metatarsophalangeal angle. Because the hallux valgus angles based on margo medialis pedis measurements were slightly but statistically significantly smaller, these measurements should be considered conservative estimates of the metatarsophalangeal angle. Significant differences between hallux valgus angles based on radiographic and non-radiographic material are unlikely. However this question has to be treated in a second stage in detail.

Vastus lateralis single motor unit EMG at the same absolute torque production at different knee angles.

PubMed

Altenburg, T M; de Haan, A; Verdijk, P W L; van Mechelen, W; de Ruiter, C J

2009-07-01

Single motor unit electromyographic (EMG) activity of the knee extensors was investigated at different knee angles with subjects (n = 10) exerting the same absolute submaximal isometric torque at each angle. Measurements were made over a 20 degrees range around the optimum angle for torque production (AngleTmax) and, where feasible, over a wider range (50 degrees ). Forty-six vastus lateralis (VL) motor units were recorded at 20.7 +/- 17.9 %maximum voluntary contraction (%MVC) together with the rectified surface EMG (rsEMG) of the superficial VL muscle. Due to the lower maximal torque capacity at positions more flexed and extended than AngleTmax, single motor unit recruitment thresholds were expected to decrease and discharge rates were expected to increase at angles above and below AngleTmax. Unexpectedly, the recruitment threshold was higher (P < 0.05) at knee angles 10 degrees more extended (43.7 +/- 22.2 N.m) and not different (P > 0.05) at knee angles 10 degrees more flexed (35.2 +/- 17.9 N.m) compared with recruitment threshold at AngleTmax (41.8 +/- 21.4 N.m). Also, unexpectedly the discharge rates were similar (P > 0.05) at the three angles: 11.6 +/- 2.2, 11.6 +/- 2.1, and 12.3 +/- 2.1 Hz. Similar angle independent discharge rates were also found for 12 units (n = 5; 7.4 +/- 5.4 %MVC) studied over the wider (50 degrees ) range, while recruitment threshold only decreased at more flexed angles. In conclusion, the similar recruitment threshold and discharge behavior of VL motor units during submaximal isometric torque production suggests that net motor unit activation did not change very much along the ascending limb of the knee-angle torque relationship. Several factors such as length-dependent twitch potentiation, which may contribute to this unexpected aspect of motor control, are discussed.

Relative effectiveness of insulin pump treatment over multiple daily injections and structured education during flexible intensive insulin treatment for type 1 diabetes: cluster randomised trial (REPOSE).

PubMed

2017-03-30

Objective  To compare the effectiveness of insulin pumps with multiple daily injections for adults with type 1 diabetes, with both groups receiving equivalent training in flexible insulin treatment. Design  Pragmatic, multicentre, open label, parallel group, cluster randomised controlled trial (Relative Effectiveness of Pumps Over MDI and Structured Education (REPOSE) trial). Setting  Eight secondary care centres in England and Scotland. Participants  Adults with type 1 diabetes who were willing to undertake intensive insulin treatment, with no preference for pumps or multiple daily injections. Participants were allocated a place on established group training courses that taught flexible intensive insulin treatment ("dose adjustment for normal eating," DAFNE). The course groups (the clusters) were then randomly allocated in pairs to either pump or multiple daily injections. Interventions  Participants attended training in flexible insulin treatment (using insulin analogues) structured around the use of pump or injections, followed for two years. Main outcome measures  The primary outcomes were a change in glycated haemoglobin (HbA1c) values (%) at two years in participants with baseline HbA1c value of ≥7.5% (58 mmol/mol), and the proportion of participants achieving an HbA1c value of <7.5%. Secondary outcomes included body weight, insulin dose, and episodes of moderate and severe hypoglycaemia. Ancillary outcomes included quality of life and treatment satisfaction. Results  317 participants (46 courses) were randomised (156 pump and 161 injections). 267 attended courses and 260 were included in the intention to treat analysis, of which 235 (119 pump and 116 injection) had baseline HbA1c values of ≥7.5%. Glycaemic control and rates of severe hypoglycaemia improved in both groups. The mean change in HbA1c at two years was -0.85% with pump treatment and -0.42% with multiple daily injections. Adjusting for course, centre, age, sex, and accounting for missing values, the difference was -0.24% (-2.7 mmol/mol) in favour of pump users (95% confidence interval -0.53 to 0.05, P=0.10). Most psychosocial measures showed no difference, but pump users showed greater improvement in treatment satisfaction and some quality of life domains (dietary freedom and daily hassle) at 12 and 24 months. Conclusions  Both groups showed clinically relevant and long lasting decreases in HbA1c, rates of severe hypoglycaemia, and improved psychological measures, although few participants achieved glucose levels currently recommended by national and international guidelines. Adding pump treatment to structured training in flexible intensive insulin treatment did not substantially enhance educational benefits on glycaemic control, hypoglycaemia, or psychosocial outcomes in adults with type 1 diabetes. These results do not support a policy of providing insulin pumps to adults with poor glycaemic control until the effects of training on participants' level of engagement in intensive self management have been determined. Trial registration  Current Controlled Trials ISRCTN61215213. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

Prediction of the noise from a propeller at angle of attack

NASA Technical Reports Server (NTRS)

Krejsa, Eugene A.

1990-01-01

An analysis is presented to predict the noise of a propeller at angle of attack. The analysis is an extension of that reported by Mani which predicted the change in noise due to angle of attack to both unsteady loading and to azimuthal variation of the radiation efficiency of steady noise sources. Mani's analysis, however, was limited to small angles of attack. The analysis reported herein removes this small angle limitation. Results from the analysis are compared with the data of Woodward for a single rotation propeller and a counter rotating propeller. The comparison shows that including the effect of angle of attack on the steady noise sources significantly improves the agreement with data. Including higher order effects of angle of attack, while changing the predicted noise at far forward and aft angles, has little effect near the propeller plane.

Contemporary Approach to the Diagnosis and Management of Primary Angle-Closure Disease.

PubMed

Razeghinejad, M Reza; Myers, Jonathan S

2018-05-16

Primary angle closure disease spectrum varies from a narrow angle to advanced glaucoma. A variety of imaging technologies may assist the clinician in determining the pathophysiology and diagnosis of primary angle closure, but gonioscopy remains a mainstay of clinical evaluation. Laser iridotomy effectively eliminates the pupillary block component of angle closure; however, studies show that in many patients the iridocorneal angle remains narrow from underlying anatomic issues, and increasing lens size often leads to further narrowing over time. Recent studies have further characterized the role of the lens in angle closure disease, and cataract or clear lens extraction is increasingly used earlier in its management. As a first surgical step in angle closure glaucoma, lens extraction alone often effectively controls the pressure with less risk of complications than concurrent or stand alone glaucoma surgery, but may not be sufficient in more advanced or severe disease. We provide a comprehensive review on the primary angle-closure disease nomenclature, imaging, and current laser and surgical management. Copyright © 2018. Published by Elsevier Inc.

Assessment of forward head posture in females: observational and photogrammetry methods.

PubMed

Salahzadeh, Zahra; Maroufi, Nader; Ahmadi, Amir; Behtash, Hamid; Razmjoo, Arash; Gohari, Mahmoud; Parnianpour, Mohamad

2014-01-01

There are different methods to assess forward head posture (FHP) but the accuracy and discrimination ability of these methods are not clear. Here, we want to compare three postural angles for FHP assessment and also study the discrimination accuracy of three photogrammetric methods to differentiate groups categorized based on observational method. All Seventy-eight healthy female participants (23 ± 2.63 years), were classified into three groups: moderate-severe FHP, slight FHP and non FHP based on observational postural assessment rules. Applying three photogrammetric methods - craniovertebral angle, head title angle and head position angle - to measure FHP objectively. One - way ANOVA test showed a significant difference in three categorized group's craniovertebral angle (P< 0.05, F=83.07). There was no dramatic difference in head tilt angle and head position angle methods in three groups. According to Linear Discriminate Analysis (LDA) results, the canonical discriminant function (Wilks'Lambda) was 0.311 for craniovertebral angle with 79.5% of cross-validated grouped cases correctly classified. Our results showed that, craniovertebral angle method may discriminate the females with moderate-severe and non FHP more accurate than head position angle and head tilt angle. The photogrammetric method had excellent inter and intra rater reliability to assess the head and cervical posture.

Auto-calibrated scanning-angle prism-type total internal reflection microscopy for nanometer-precision axial position determination and optional variable-illumination-depth pseudo total internal reflection microscopy

DOEpatents

Fang, Ning; Sun, Wei

2015-04-21

A method, apparatus, and system for improved VA-TIRFM microscopy. The method comprises automatically controlled calibration of one or more laser sources by precise control of presentation of each laser relative a sample for small incremental changes of incident angle over a range of critical TIR angles. The calibration then allows precise scanning of the sample for any of those calibrated angles for higher and more accurate resolution, and better reconstruction of the scans for super resolution reconstruction of the sample. Optionally the system can be controlled for incident angles of the excitation laser at sub-critical angles for pseudo TIRFM. Optionally both above-critical angle and sub critical angle measurements can be accomplished with the same system.

Vehicle Characteristics

DTIC Science & Technology

2008-02-14

g. Material. 5.1.7 Wheel Geometry. a. Camber angle. b. Caster angle. c. Pivot angle. d. Static toe-in. e. Turning angles...the vehicle characteristics to be obtained during testing of wheeled and tracked vehicles and their components. Physical characterization of test...frontal area Characteristic data sheet Power train Suspention Wheel geometry Vehicle clearance angles Armament Gun control systems 16. SECURITY

Undetected angle closure in patients with a diagnosis of open-angle glaucoma.

PubMed

Varma, Devesh K; Simpson, Sarah M; Rai, Amandeep S; Ahmed, Iqbal Ike K

2017-08-01

The aim of this study was to identify the proportion of patients referred to a tertiary glaucoma centre with a diagnosis of open-angle glaucoma (OAG) who were found to have angle closure glaucoma. Retrospective chart review. Consecutive new patients referred for glaucoma management to a tertiary centre between July 2010 and December 2011 were reviewed. Patients whose referrals for glaucoma assessment specified angle status as "open" were included. The data collected included glaucoma specialist's angle assessment, diagnosis, and glaucoma severity. The status of those with 180 degrees or more Shaffer angle grading of 0 was classified as "closed." From 1234 glaucoma referrals, 179 cases were specified to have a diagnosis of OAG or when angles were known to be open. Of these, 16 (8.9%) were found on examination by the glaucoma specialist to have angle closure. Pseudoexfoliation was present in 4 of 16 patients (25%) in the missed angle-closure glaucoma (ACG) group and 22 of 108 patients (13.5%) in the remaining OAG group. There was no difference found in demographic or ocular biometric parameters between those with confirmed OAG versus those with missed ACG. Almost 1 in 11 patients referred by ophthalmologists to a tertiary glaucoma centre with a diagnosis of OAG were in fact found to have angle closure. Given the different treatment approaches for ACG versus OAG, this study suggests a need to strengthen angle evaluations. Copyright © 2017 Canadian Ophthalmological Society. Published by Elsevier Inc. All rights reserved.

Anterior Segment Imaging for Angle Closure.

PubMed

Chansangpetch, Sunee; Rojanapongpun, Prin; Lin, Shan C

2018-04-01

To summarize the role of anterior segment imaging (AS-imaging) in angle closure diagnosis and management, and the possible advantages over the current standard of gonioscopy. Literature review and perspective. Review of the pertinent publications with interpretation and perspective in relation to the use of AS-imaging in angle closure assessment focusing on anterior segment optical coherence tomography and ultrasound biomicroscopy. Several limitations have been encountered with the reference standard of gonioscopy for angle assessment. AS-imaging has been shown to have performance in angle closure detection compared to gonioscopy. Also, imaging has greater reproducibility and serves as better documentation for long-term follow-up than conventional gonioscopy. The qualitative and quantitative information obtained from AS-imaging enables better understanding of the underlying mechanisms of angle closure and provides useful parameters for risk assessment and possible prediction of the response to laser and surgical intervention. The latest technologies-including 3-dimensional imaging-have allowed for the assessment of the angle that simulates the gonioscopic view. These advantages suggest that AS-imaging has a potential to be a reference standard for the diagnosis and monitoring of angle closure disease in the future. Although gonioscopy remains the primary method of angle assessment, AS-imaging has an increasing role in angle closure screening and management. The test should be integrated into clinical practice as an adjunctive tool for angle assessment. It is arguable that AS-imaging should be considered first-line screening for patients at risk for angle closure. Copyright © 2018 Elsevier Inc. All rights reserved.

Influence of SiC grain boundary character on fission product transport in irradiated TRISO fuel

NASA Astrophysics Data System (ADS)

Lillo, T. M.; van Rooyen, I. J.

2016-05-01

In this study, the fission product precipitates at silicon carbide grain boundaries from an irradiated TRISO particle were identified and correlated with the associated grain boundary characteristics. Precession electron diffraction in the transmission electron microscope provided the crystallographic information needed to identify grain boundary misorientation and boundary type (i.e., low angle, random high angle or coincident site lattice (CSL)-related). The silicon carbide layer was found to be composed mainly of twin boundaries and small fractions of random high angle and low angle grain boundaries. Most fission products were found at random, high-angle grain boundaries, with small fractions at low-angle and CSL-related grain boundaries. Palladium (Pd) was found at all types of grain boundaries while Pd-uranium and Pd-silver precipitates were only associated with CSL-related and random, high-angle grain boundaries. Precipitates containing only Ag were found only at random, high-angle grain boundaries, but not at low angle or CSL-related grain boundaries.

Sharper angle, higher risk? The effect of cutting angle on knee mechanics in invasion sport athletes.

PubMed

Schreurs, Mervin J; Benjaminse, Anne; Lemmink, Koen A P M

2017-10-03

Cutting is an important skill in team-sports, but unfortunately is also related to non-contact ACL injuries. The purpose was to examine knee kinetics and kinematics at different cutting angles. 13 males and 16 females performed cuts at different angles (45°, 90°, 135° and 180°) at maximum speed. 3D kinematics and kinetics were collected. To determine differences across cutting angles (45°, 90°, 135° and 180°) and sex (female, male), a 4×2 repeated measures ANOVA was conducted followed by post hoc comparisons (Bonferroni) with alpha level set at α≤0.05a priori. At all cutting angles, males showed greater knee flexion angles than females (p<0.01). Also, where males performed all cutting angles with no differences in the amount of knee flexion -42.53°±8.95°, females decreased their knee flexion angle from -40.6°±7.2° when cutting at 45° to -36.81°±9.10° when cutting at 90°, 135° and 180° (p<0.01). Knee flexion moment decreased for both sexes when cutting towards sharper angles (p<0.05). At 90°, 135° and 180°, males showed greater knee valgus moments than females. For both sexes, knee valgus moment increased towards the sharper cutting angles and then stabilized compared to the 45° cutting angle (p<0.01). Both females and males showed smaller vGRF when cutting to sharper angles (p<0.01). It can be concluded that different cutting angles demand different knee kinematics and kinetics. Sharper cutting angles place the knee more at risk. However, females and males handle this differently, which has implications for injury prevention. Copyright © 2017 Elsevier Ltd. All rights reserved.

A Comparative Study of Some Dynamic Stall Models

NASA Technical Reports Server (NTRS)

Reddy, T. S. R.; Kaza, K. R. V.

1987-01-01

Three semi-empirical aerodynamic stall models are compared with respect to their lift and moment hysteresis loop prediction, limit cycle behavior, easy implementation, and feasibility in developing the parameters required for stall flutter prediction of advanced turbines. For the comparison of aeroelastic response prediction including stall, a typical section model and a plate structural model are considered. The response analysis includes both plunging and pitching motions of the blades. In model A, a correction to the angle of attack is applied when the angle of attack exceeds the static stall angle. In model B, a synthesis procedure is used for angles of attack above static stall angles and the time history effects are accounted through the Wagner function. In both models the life and moment coefficients for angle of attack below stall are obtained from tabular data for a given Mach number and angle of attack. In model C, referred to an the ONERA model, the life and moment coefficients are given in the form of two differential equations, one for angles below stall, and the other for angles above stall. The parameters of those equations are nonlinear functions of the angle of attack.

Associations between Narrow Angle and Adult Anthropometry: The Liwan Eye Study

PubMed Central

Jiang, Yuzhen; He, Mingguang; Friedman, David S.; Khawaja, Anthony P.; Lee, Pak Sang; Nolan, Winifred P.; Yin, Qiuxia; Foster, Paul J.

2015-01-01

Purpose To assess the associations between narrow angle and adult anthropometry. Methods Chinese adults aged 50 years and older were recruited from a population-based survey in the Liwan District of Guangzhou, China. Narrow angle was defined as the posterior trabecular meshwork not visible under static gonioscopy in at least three quadrants (i.e. a circumference of at least 270°). Logistic regression models were used to examine the associations between narrow angle and anthropomorphic measures (height, weight and body mass index, BMI). Results Among the 912 participants, lower weight, shorter height, and lower BMI were significantly associated with narrower angle width (tests for trend: mean angle width in degrees vs weight p<0.001; vs height p<0.001; vs BMI p = 0.012). In univariate analyses, shorter height, lower weight and lower BMI were all significantly associated with greater odds of narrow angle. The crude association between height and narrow angle was largely attributable to a stronger association with age and sex. Lower BMI and weight remained significantly associated with narrow angle after adjustment for height, age, sex, axial ocular biometric measures and education. In analyses stratified by sex, the association between BMI and narrow angle was only observed in women. Conclusion Lower BMI and weight were associated with significantly greater odds of narrow angle after adjusting for age, education, axial ocular biometric measures and height. The odds of narrow angle increased 7% per 1 unit decrease in BMI. This association was most evident in women. PMID:24707840

Associations between narrow angle and adult anthropometry: the Liwan Eye Study.

PubMed

Jiang, Yuzhen; He, Mingguang; Friedman, David S; Khawaja, Anthony P; Lee, Pak Sang; Nolan, Winifred P; Yin, Qiuxia; Foster, Paul J

2014-06-01

To assess the associations between narrow angle and adult anthropometry. Chinese adults aged 50 years and older were recruited from a population-based survey in the Liwan District of Guangzhou, China. Narrow angle was defined as the posterior trabecular meshwork not visible under static gonioscopy in at least three quadrants (i.e. a circumference of at least 270°). Logistic regression models were used to examine the associations between narrow angle and anthropomorphic measures (height, weight and body mass index, BMI). Among the 912 participants, lower weight, shorter height, and lower BMI were significantly associated with narrower angle width (tests for trend: mean angle width in degrees vs weight p < 0.001; vs height p < 0.001; vs BMI p = 0.012). In univariate analyses, shorter height, lower weight and lower BMI were all significantly associated with greater odds of narrow angle. The crude association between height and narrow angle was largely attributable to a stronger association with age and sex. Lower BMI and weight remained significantly associated with narrow angle after adjustment for height, age, sex, axial ocular biometric measures and education. In analyses stratified by sex, the association between BMI and narrow angle was only observed in women. Lower BMI and weight were associated with significantly greater odds of narrow angle after adjusting for age, education, axial ocular biometric measures and height. The odds of narrow angle increased 7% per 1 unit decrease in BMI. This association was most evident in women.

Comparison of robotic-assisted and conventional manual implantation of a primary total knee arthroplasty.

PubMed

Park, Sang Eun; Lee, Chun Taek

2007-10-01

This study was aimed to compare robotic-assisted implantation of a total knee arthroplasty with conventional manual implantation. We controlled, randomized, and reviewed 72 patients for total knee arthroplasty assigned to undergo either conventional manual implantation (excluding navigation-assisted implantation cases) of a Zimmer LPS prosthesis (Zimmer, Warsaw, Ind) (30 patients: group 1) or robotic-assisted implantation of such a prosthesis (32 patients: group 2). The femoral flexion angle (gamma angle) and tibial angle (delta angle) in the lateral x-ray of group 1 were 4.19 +/- 3.28 degrees and 89.7 +/- 1.7 degrees, and those of group 2 were 0.17 +/- 0.65 degrees and 85.5 +/- 0.92 degrees. The major complications were from improper small skin incision during a constraint attempt of minimally invasive surgery and during bulk fixation frame pins insertion. Robotic-assisted technology had definite advantages in terms of preoperative planning, accuracy of the intraoperative procedure, and postoperative follow-up, especially in the femoral flexion angle (gamma angle) and tibial flexion angle (delta angle) in the lateral x-ray, and in the femoral flexion angle (alpha angle) in the anteroposterior x-ray. But a disadvantage was the high complication rate in early stage.

Measuring Contours of Coal-Seam Cuts

NASA Technical Reports Server (NTRS)

1983-01-01

Angle transducers measure angle between track sections as longwall shearer proceeds along coal face. Distance transducer functions in conjunction with angle transducers to obtain relative angles at known positions. When cut is complete, accumulated data are stored on cassette tape, and track profile is computed and displayed. Micro-processor-based instrument integrates small changes in angle and distance.

Analysis of Slug Test Response in a Fracture of a Large Dipping Angle

NASA Astrophysics Data System (ADS)

Chen, C.

2013-12-01

A number of cross-borehole slug tests were conducted in a Cenozoic folded sandstone formation, where a fracture has a dipping angle as large as 47°. As all the slug test models available in literature assume the formation to be horizontal, a slug test model taking into account the dipping angle effect is developed herein. Due to the presence of the dipping angle, there is a uniform regional groundwater flow, and the flow field generated by the test is not raidally symmetrical with respect to the test well. When the fracture hydraulic conductivity is relatively low, a larger dipping angle causes larger wellbore flow rates, leading to a faster recovery of the non-oscillatory test response. When the fracture hydraulic conductivity is relatively high, a larger dipping angle causes smaller wellbore heads, resulting in an increase of amplitude of the oscillatory test response; yet little influence on the frequency of oscillation. In general, neglecting the dipping angle may lead to an overestimate of hydraulic conductivity and an underestimate of the storage coefficient. The dipping angle effect is more pronounced for a larger storage coefficient, being less sensitive to transmissivity. An empirical relationship is developed for the minimum dipping angle, smaller than which the dipping angle effect can be safely neglected, as a function of the dimensionless storage coefficient. This empirical relationship helps evaluate whether or not the dipping angle needs to be considered in data analysis. The slug test data in the fracture of a 47°dipping angle is analyzed using the current model, and it is found that neglecting the dip angle can result in a 30% overestimate of transmissivity and a 61% underestimate of the storage coefficient.

Influence of laser beam incidence angle on laser lap welding quality of galvanized steels

NASA Astrophysics Data System (ADS)

Mei, Lifang; Yan, Dongbing; Chen, Genyu; Wang, Zhenhui; Chen, Shuixuan

2017-11-01

Based on the characteristics of laser welded structural parts of auto bodies, the influence of variation in laser beam incidence angle on the lap welding performance of galvanized auto-body sheets was studied. Lap welding tests were carried out on the galvanized sheets for auto-body application at different laser beam incidence angles by using the optimal welding parameters obtained through orthogonal experiment. The effects of incidence angle variation on seam appearance, cross-sectional shape, joint mechanical properties and microstructure of weldments were analyzed. In addition, the main factors influencing the value of incidence angle were investigated. According to the results, the weld seams had a good appearance as well as a fine, and uniform microstructure when the laser beam incidence angle was smaller than the critical incidence angle, and thus they could withstand great tensile and shear loads. Moreover, all tensile-shear specimens were fractured in the base material zone. When the laser beam incidence angle was larger than the critical incidence angle, defects like shrinkage and collapse tended to emerge, thereby resulting in the deteriorated weldability of specimens. Meanwhile, factors like the type and thickness of sheet, weld width as well as inter-sheet gap all had a certain effect on the value of laser beam incidence angle. When the sheet thickness was small and the weld width was narrow, the laser beam incidence angle could be increased appropriately. At the same time, small changes in the inter-sheet gap could greatly impact the value of incidence angle. When the inter-sheet gap was small, the laser beam incidence angle should not be too large.

A Novel Method to Measure the Tentorial Angle and the Implications on Surgeries of the Pineal Region.

PubMed

Syed, Hasan R; Jean, Walter C

2018-03-01

There is no standard way to define the angle of the tentorium. The current trend to use the Twining line to define this angle has significant pitfalls. The goal of the current study was to provide a new and accurate way to measure the tentorial angle and demonstrate its impact on surgeries of the pineal region. A new technique (n-angle) to measure the tentorial angle was introduced using the floor of the fourth ventricle and the torcula. Comparisons with older techniques were made to illustrate reliability. Midline sagittal MR images were used to measure the tentorial angle in 240 individuals to obtain population-based data. A cohort of 8 patients who underwent either the infratentorial or the transtentorial approach to the pineal or upper vermian region were examined in search of correlations between tentorial angle and surgical approach. The data in this study showed that the Twining line technique understates the tentorial angle in people with low-lying torcula. The n-angle is more reliable in reflecting the true steepness of the tentorium regardless of torcula position. On average, men have slightly steeper tentoriums. In the clinical cohort, all patients who underwent infratentorial surgery had tentorial angles <55°, whereas the majority of patients who underwent transtentorial surgeries had angles >67°. The n-angle provides a reliable and accurate way to describe the slope of the tentorium. The population-based average of 60° may be a useful measurement to influence the choice of surgical approach, either under or through the tentorium, to the pineal region. Copyright © 2017 Elsevier Inc. All rights reserved.

Reliability of Two Smartphone Applications for Radiographic Measurements of Hallux Valgus Angles.

PubMed

Mattos E Dinato, Mauro Cesar; Freitas, Marcio de Faria; Milano, Cristiano; Valloto, Elcio; Ninomiya, André Felipe; Pagnano, Rodrigo Gonçalves

The objective of the present study was to assess the reliability of 2 smartphone applications compared with the traditional goniometer technique for measurement of radiographic angles in hallux valgus and the time required for analysis with the different methods. The radiographs of 31 patients (52 feet) with a diagnosis of hallux valgus were analyzed. Four observers, 2 with >10 years' experience in foot and ankle surgery and 2 in-training surgeons, measured the hallux valgus angle and intermetatarsal angle using a manual goniometer technique and 2 smartphone applications (Hallux Angles and iPinPoint). The interobserver and intermethod reliability were estimated using intraclass correlation coefficients (ICCs), and the time required for measurement of the angles among the 3 methods was compared using the Friedman test. A very good or good interobserver reliability was found among the 4 observers measuring the hallux valgus angle and intermetatarsal angle using the goniometer (ICC 0.913 and 0.821, respectively) and iPinPoint (ICC 0.866 and 0.638, respectively). Using the Hallux Angles application, a very good interobserver reliability was found for measurements of the hallux valgus angle (ICC 0.962) and intermetatarsal angle (ICC 0.935) only among the more experienced observers. The time required for the measurements was significantly shorter for the measurements using both smartphone applications compared with the goniometer method. One smartphone application (iPinPoint) was reliable for measurements of the hallux valgus angles by either experienced or nonexperienced observers. The use of these tools might save time in the evaluation of radiographic angles in the hallux valgus. Copyright © 2016 American College of Foot and Ankle Surgeons. Published by Elsevier Inc. All rights reserved.

Gimbal-Angle Vectors of the Nonredundant CMG Cluster

NASA Astrophysics Data System (ADS)

Lee, Donghun; Bang, Hyochoong

2018-05-01

This paper deals with the method using the preferred gimbal angles of a control moment gyro (CMG) cluster for controlling spacecraft attitude. To apply the method to the nonredundant CMG cluster, analytical gimbal-angle solutions for the zero angular momentum state are derived, and the gimbal-angle vectors for the nonzero angular momentum states are studied by a numerical method. It will be shown that the number of the gimbal-angle vectors is determined from the given skew angle and the angular momentum state of the CMG cluster. Through numerical examples, it is shown that the method using the preferred gimbal-angle is an efficient approach to avoid internal singularities for the nonredundant CMG cluster.

Demonstration of angle widening using EyeCam after laser peripheral iridotomy in eyes with angle closure.

PubMed

Perera, Shamira A; Quek, Desmond T; Baskaran, Mani; Tun, Tin A; Kumar, Rajesh S; Friedman, David S; Aung, Tin

2010-06-01

To evaluate EyeCam in detecting changes in angle configuration after laser peripheral iridotomy (LPI) in comparison to gonioscopy, the reference standard. Prospective comparative study. Twenty-four subjects (24 eyes) with primary angle-closure glaucoma (PACG) were recruited. Gonioscopy and EyeCam (Clarity Medical Systems) imaging of all 4 angle quadrants were performed, before and 2 weeks after LPI. Images were graded according to angle structures visible by an observer masked to clinical data or the status of LPI, and were performed in a random order. Angle closure in a quadrant was defined as the inability to visualize the posterior trabecular meshwork. We determined the number of quadrants with closed angles and the mean number of clock hours of angle closure before and after LPI in comparison to gonioscopy. Using EyeCam, all 24 eyes showed at least 1 quadrant of angle widening after LPI. The mean number of clock hours of angle closure decreased significantly, from 8.15 +/- 3.47 clock hours before LPI to 1.75 +/- 2.27 clock hours after LPI (P < .0001, Wilcoxon signed rank test). Overall, gonioscopy showed 1.0 +/- 1.41 (95% CI, 0.43-1.57) quadrants opening from closed to open after LPI compared to 2.0 +/- 1.28 (95% CI, 1.49-2.51, P = .009) quadrants with EyeCam. Intra-observer reproducibility of grading the extent of angle closure in clock hours in EyeCam images was moderate to good (intraclass correlation coefficient 0.831). EyeCam may be used to document changes in angle configuration after LPI in eyes with PACG. Copyright 2010 Elsevier Inc. All rights reserved.

Kappa angles in different positions in patients with myopia during LASIK

PubMed Central

Qi, Hui; Jiang, Jing-Jing; Jiang, Yan-Ming; Wang, Li-Qiang; Huang, Yi-Fei

2016-01-01

AIM To investigate the difference in kappa angle between sitting and supine positions during laser-assisted in situ keratomileusis (LASIK). METHODS A retrospective study was performed on 395 eyes from 215 patients with myopia that received LASIK. Low, moderate, and high myopia groups were assigned according to diopters. The horizontal and vertical components of kappa angle in sitting position were measured before the operation, and in supine position during the operation. The data from the two positions were compared and the relationship between kappa angle and diopters were analyzed. RESULTS Two hundred and twenty-three eyes (56.5%) in sitting position and 343 eyes (86.8%) in supine position had positive kappa angles. There were no significant differences in horizontal and vertical components of kappa angle in the sitting position or horizontal components of kappa angle in the supine position between the three groups (P>0.05). A significant difference in the vertical components of kappa angle in the supine position was seen in the three groups (P<0.01). Differences in both horizontal and vertical components of kappa angles were significant between the sitting and supine positions. Positive correlations in both horizontal and vertical components of kappa angles (P<0.05) were found and vertical components of kappa angle in sitting and supine positions were negatively correlated with the degree of myopia (sitting position: r=-0.109; supine position: r=-0.172; P<0.05). CONCLUSION There is a correlation in horizontal and vertical components of kappa angle in sitting and supine positions. Positive correlations in both horizontal and vertical components of kappa angle in sitting and supine positions till the end of the results. This result still needs further observation. Clinicians should take into account different postures when excimer laser surgery needs to be performed. PMID:27162734

Mechanism For Adjustment Of Commutation Of Brushless Motor

NASA Technical Reports Server (NTRS)

Schaefer, Richard E.

1995-01-01

Mechanism enables adjustment of angular position of set of Hall-effect devices that sense instantaneous shaft angle of brushless dc motor. Outputs of sensors fed to commutation circuitry. Measurement of shaft angle essential for commutation; that is, application of voltage to stator windings must be synchronized with shaft angle. To obtain correct angle measurement for commutation, Hall-effect angle sensors positioned at proper reference angle. The present mechanism accelerates adjustment procedure and makes it possible to obtain more accurate indication of minimum-current position because it provides for adjustment while motor running.

Survival and Growth of Cottonwood Clones After Angle Planting and Base Angle Treatments

Treesearch

W.K. Randall; Harvey E. Kennedy

1976-01-01

Presently, commercial cottonwood plantations in the lower Mississippi Valley are established using vertically planted, unrooted cuttings with a flat (90°) base. Neither survival nor first-year growth of a group of six Stoneville clones was improved by angle planting or cutting base angles diagonally. For one clone, survival was significantly better when base angle was...

Transverse tails and higher order moments

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

Spence, W.L.; Decker, F.J.; Woodley, M.D.

1993-05-01

The tails that may be engendered in a beam`s transverse phase space distribution by, e.g., intrabunch wakefields and nonlinear magnetic fields, are all important diagnostic and object of tuning in linear colliders. Wire scanners or phosphorescent screen monitors yield one dimensional projected spatial profiles of such beams that are generically asymmetric around their centroids, and therefore require characterization by the third moment {l_angle}x{sup 3}{r_angle} in addition to the conventional mean-square or second moment. A set of measurements spread over sufficient phase advance then allows the complete set {l_angle}x{sup 3}{r_angle}, {l_angle}xx{prime}{sup 2}{r_angle}, {l_angle}x{prime}{sup 3}{r_angle}, and {l_angle}x{sup 2}x{prime}{r_angle} to be deduced --more » the natural extension of the well-known ``emittance measurement`` treatment of second moments. The four third moments may be usefully decomposed into parts rotating in phase space at the {beta}-tron frequency and at its third harmonic, each specified by a phase-advance-invariant amplitude and a phase. They provide a framework for the analysis and tuning of transverse wakefield tails.« less

Ocular Biometrics of Myopic Eyes With Narrow Angles.

PubMed

Chong, Gabriel T; Wen, Joanne C; Su, Daniel Hsien-Wen; Stinnett, Sandra; Asrani, Sanjay

2016-02-01

The purpose of this study was to compare the ocular biometrics between myopic patients with and without narrow angles. Patients with a stable myopic refraction (myopia worse than -1.00 D spherical equivalent) were prospectively recruited. Angle status was assessed using gonioscopy and biometric measurements were performed using an anterior segment optical coherence tomography and an IOLMaster. A total of 29 patients (58 eyes) were enrolled with 13 patients (26 eyes) classified as having narrow angles and 16 patients (32 eyes) classified as having open angles. Baseline demographics of age, sex, and ethnicity did not differ significantly between the 2 groups. The patients with narrow angles were on average older than those with open angles but the difference did not reach statistical significance (P=0.12). The central anterior chamber depth was significantly less in the eyes with narrow angles (P=0.05). However, the average lens thickness, although greater in the eyes with narrow angles, did not reach statistical significance (P=0.10). Refractive error, axial lengths, and iris thicknesses did not differ significantly between the 2 groups (P=0.32, 0.47, 0.15). Narrow angles can occur in myopic eyes. Routine gonioscopy is therefore recommended for all patients regardless of refractive error.

Correlation between extension-block K-wire insertion angle and postoperative extension loss in mallet finger fracture.

PubMed

Lee, S K; Kim, Y H; Moon, K H; Choy, W S

2018-02-01

Extension-block pinning represents a simple and reliable surgical technique. Although this procedure is commonly performed successfully, some patients develop postoperative extension loss. To date, the relationship between extension-block Kirschner wire (K-wire) insertion angle and postoperative extension loss in mallet finger fracture remains unclear. We aimed to clarify this relationship and further evaluate how various operative and non-operative factors affect postoperative extension loss after extension-block pinning for mallet finger fracture. A retrospective study was conducted to investigate a relationship between extension block K-wire insertion angle and postoperative extension loss. The inclusion criteria were: (1) a dorsal intra-articular fracture fragment involving 30% of the base of the distal phalanx with or without volar subluxation of the distal phalanx; and (2) <3 weeks delay from the injury without treatment. Extension-block K-wire insertion angle and fixation angle of the distal interphalangeal (DIP) joint were assessed using lateral radiograph at immediate postoperative time. Postoperative extension loss was assessed by using lateral radiograph at latest follow-up. Extension-block K-wire insertion angle was defined as the acute angle between extension block K-wire and longitudinal axis of middle phalangeal head. DIP joint fixation angle was defined as the acute angle between the distal phalanx and middle phalanx longitudinal axes. Seventy-five patients were included. The correlation analysis revealed that extension-block K-wire insertion angle had a negative correlation with postoperative extension loss, whereas fracture size and time to operation had a positive correlation (correlation coefficient for extension block K-wire angle: -0.66, facture size: +0.67, time to operation: +0.60). When stratifying patients in terms of negative and positive fixation angle of the DIP joint, the independent t-test showed that mean postoperative extension loss is -3.67° and +4.54° (DIP joint fixation angles of <0° and ≥0°, respectively, P=0.024). When stratifying patients in terms of extension-block K-wire insertion angle (30°, 30°-40°, >40°), ANOVA showed significantly less postoperative extension loss for higher insertion angles (>40°) than for medium insertion angles (30°-40°). Mean postoperative extension loss difference between higher insertion angle (>40°) and medium insertion angle (30°-40°) was 11° (P=0.002). Using an insertion angle of the extension-block K-wire of 40°-45° and a slightly hyperextended position of the DIP joint may help reducing postoperative extension loss. Therapeutic level III. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

Incident angle of saltating particles in wind-blown sand.

PubMed

Fu, Lin-Tao; Bo, Tian-Li; Gu, Hai-Hua; Zheng, Xiao-Jing

2013-01-01

Incident angle of saltating particles plays a very important role in aeolian events. In this paper, the incident angles of sand particles near the sand bed were measured in wind tunnel. It reveals that the incident angles range widely from 0° to 180° and thereby the means of angles are larger than published data. Surprisingly, it is found the proportion that angles of 5°-15° occupy is far below previous reports. The measuring height is probably the most important reason for the measurement differences between this study and previous investigations.

The gonial angle stripper: an instrument for the treatment of prominent gonial angle.

PubMed

Kyutoku, S; Yanagida, A; Kusumoto, K; Ogawa, Y

1994-12-01

In the Orient, a prominent gonial angle, so-called benign masseteric hypertrophy, is rather common and considered unattractive. Therefore, its surgical correction is one of the most popular forms of facial skeletal contouring. For accurate and safe osteotomy of the mandibular angle region, a gonial angle stripper was specially invented. It has a small projection that will ease identification of the osteotomy line in a narrow operative field. The tool has been clinically used in eight patients to prove its usefulness, especially for a posteriorly developed mandibular angle.

Three-Dimensional Analysis of Mandibular Angle Classification and Aesthetic Evaluation of the Lower Face in Chinese Female Adults.

PubMed

Mao, Xiaoyan; Fu, Xi; Niu, Feng; Chen, Ying; Jin, Qi; Qiao, Jia; Gui, Lai

2018-05-14

Reduction gonioplasty is very popular in East Asia. However, there has been little quantitative criteria for mandibular angle classification or aesthetics. The aim of this study was to investigate the quantitative differences of mandibular angle types and determine the morphologic features of mandibular angle in attractive women. We created a database of skull computed tomography and standardized frontal and lateral photographs of 96 Chinese female adults. Mandibular angle was classified into 3 groups, namely, extraversion, introversion, and healthy group, based on the position of gonion. We used a 5-point Likert scale to quantify attractiveness based on photographs. Those who scored 4 or higher were defined as attractive women. Three types of computed tomography measurements of the mandible were taken, including 4 distances, 4 angles, and 3 proportions. Discriminant analysis was applied to establish a mathematic model for mandibular angle aesthetics evaluation. Significant differences were observed between the different types of mandibular angle in lower facial width (Gol-Gor), mandibular angle (Co-Go-Me), and gonion divergence angle (Gol-Me-Gor) (P < 0.01). Chinese attractive women had a mandibular angle of 123.913 ± 2.989 degrees, a FH-MP of 27.033 ± 2.695 degrees, and a Go-Me/Co-Go index of 2.0. The "healthy" women had a mandibular angle of 116.402 ± 5.373 degrees, a FH-MP of 19.556 ± 5.999 degrees, and a Go-Me/Co-Go index of 1.6. The estimated Fisher linear discriminant function for the identification of attractive women was as follows: Y = -0.1516X1(Co-Go) + 0.128X2(Go-Me) + 0.04936X3(Co-Go-Me) +0.0218X4(FH-MP). Our study quantified the differences of mandibular angle types and identified the morphological features of mandibular angle in attractive Chinese female adults. Our results could assist plastic surgeons in presurgical designing of new aesthetic gonion and help to evaluate lower face aesthetics.

A Different Angle on Perspective

ERIC Educational Resources Information Center

Frantz, Marc

2012-01-01

When a plane figure is photographed from different viewpoints, lengths and angles appear distorted. Hence it is often assumed that lengths, angles, protractors, and compasses have no place in projective geometry. Here we describe a sense in which certain angles are preserved by projective transformations. These angles can be constructed with…

Determination of corrections to flow direction measurements obtained with a wing-tip mounted sensor. M.S. Thesis

NASA Technical Reports Server (NTRS)

Moul, T. M.

1983-01-01

The nature of corrections for flow direction measurements obtained with a wing-tip mounted sensor was investigated. Corrections for the angle of attack and sideslip, measured by sensors mounted in front of each wing tip of a general aviation airplane, were determined. These flow corrections were obtained from both wind-tunnel and flight tests over a large angle-of-attack range. Both the angle-of-attack and angle-of-sideslip flow corrections were found to be substantial. The corrections were a function of the angle of attack and angle of sideslip. The effects of wing configuration changes, small changes in Reynolds number, and spinning rotation on the angle-of-attack flow correction were found to be small. The angle-of-attack flow correction determined from the static wind-tunnel tests agreed reasonably well with the correction determined from flight tests.

Prediction of the noise from a propeller at angle of attack

NASA Technical Reports Server (NTRS)

Krejsa, Eugene A.

1990-01-01

An analysis is presented to predict the noise of a propeller at angle of attack. The analysis is an extension of that reported by Mani (1990) which predicted the change in noise due to angle of attack due to both unsteady loading and to azimuthal variation of the radiation efficiency of steady noise sources. Mani's analysis, however, was limited to small angles of attack. The analysis reported herein removes this small angle limitation. Results from the analysis are compared with the data of Woodward (1987, 1988), for a single rotation propeller and for a counter rotating propeller. The comparison shows that including the effect of angle of attack on the steady noise sources significantly improves the agreement with data. Including higher order effects of angle of attack, while changing the predicted noise at far forward and aft angles, has little effect near the propeller plane.

Three-dimensional orientation and location-dependent varying rules of radiographic angles of the acetabular cup.

PubMed

Zhao, Jing-Xin; Su, Xiu-Yun; Zhao, Zhe; Xiao, Ruo-Xiu; Zhang, Li-Cheng; Tang, Pei-Fu

2018-02-17

The aim of this study is to demonstrate the varying rules of radiographic angles following varying three-dimensional (3D) orientations and locations of cup using an accurate mathematical model. A cone model is established to address the quantitative relationship between the opening circle of cup and its ellipse projection on radiograph. The varying rules of two-dimensional (2D) radiographic anteversion (RA) and inclination (RI) angles can be analyzed. When the centre of cup is located above X-ray source, with proper 3D RI/RA angles, 2D RA angle can be equal to its 3D counterpart, and 2D RI angle is usually greater than its 3D counterpart. Except for the original point on hip-centered anterior-posterior radiograph, there is no area on radiograph where both 2D RA and RI angles are equal to their 3D counterparts simultaneously. This study proposes an innovative model for accurately explaining how 2D RA/RI angles of cup are varying following different 3D RA/RI angles and location of cup. The analysis results provide clinicians an intuitive grasp of knowledge about 2D RA/RI angles greater or smaller than their 3D counterparts post-operatively. The established model may allow determining the effects of pelvic rotations on 2D radiographic angles of cup.

Particle beam injector system and method

DOEpatents

Guethlein, Gary

2013-06-18

Methods and devices enable coupling of a charged particle beam to a radio frequency quadrupole accelerator. Coupling of the charged particle beam is accomplished, at least in-part, by relying on of sensitivity of the input phase space acceptance of the radio frequency quadrupole to the angle of the input charged particle beam. A first electric field across a beam deflector deflects the particle beam at an angle that is beyond the acceptance angle of the radio frequency quadrupole. By momentarily reversing or reducing the established electric field, a narrow portion of the charged particle beam is deflected at an angle within the acceptance angle of the radio frequency quadrupole. In another configuration, beam is directed at an angle within the acceptance angle of the radio frequency quadrupole by the first electric field and is deflected beyond the acceptance angle of the radio frequency quadrupole due to the second electric field.

Multi-objective Optimization of Solar Irradiance and Variance at Pertinent Inclination Angles

NASA Astrophysics Data System (ADS)

Jain, Dhanesh; Lalwani, Mahendra

2018-05-01

The performance of photovoltaic panel gets highly affected bychange in atmospheric conditions and angle of inclination. This article evaluates the optimum tilt angle and orientation angle (surface azimuth angle) for solar photovoltaic array in order to get maximum solar irradiance and to reduce variance of radiation at different sets or subsets of time periods. Non-linear regression and adaptive neural fuzzy interference system (ANFIS) methods are used for predicting the solar radiation. The results of ANFIS are more accurate in comparison to non-linear regression. These results are further used for evaluating the correlation and applied for estimating the optimum combination of tilt angle and orientation angle with the help of general algebraic modelling system and multi-objective genetic algorithm. The hourly average solar irradiation is calculated at different combinations of tilt angle and orientation angle with the help of horizontal surface radiation data of Jodhpur (Rajasthan, India). The hourly average solar irradiance is calculated for three cases: zero variance, with actual variance and with double variance at different time scenarios. It is concluded that monthly collected solar radiation produces better result as compared to bimonthly, seasonally, half-yearly and yearly collected solar radiation. The profit obtained for monthly varying angle has 4.6% more with zero variance and 3.8% more with actual variance, than the annually fixed angle.

High prevalence of narrow angles among Chinese-American glaucoma and glaucoma suspect patients.

PubMed

Seider, Michael I; Pekmezci, Melike; Han, Ying; Sandhu, Simi; Kwok, Shiu Y; Lee, Roland Y; Lin, Shan C

2009-01-01

To evaluate the prevalence of gonioscopically narrow angles in a Chinese-American population with glaucoma or glaucoma suspicion. Charts from all Chinese-American patients seen in a comprehensive ophthalmology clinic in the Chinatown district of San Francisco in 2002 were reviewed. One eye from each patient with glaucoma or glaucoma suspicion that met inclusion criteria was included (n=108). Data were collected for sex, age, race (self-declared), refraction (spherical equivalent), intraocular pressure, gonioscopy, and vertical cup-to-disk ratio. Sixty percent (n=65) of Chinese-American eyes with glaucoma or glaucoma suspicion had gonioscopically narrow angles (Shaffer grade < or = 2 in 3 or more quadrants). Those with narrow angles were significantly older (P=0.004) than their open angle counterparts, but the 2 groups did not differ in terms of sex, refraction, intraocular pressure, or cup-to-disk ratio (all, P > or = 0.071). In a multivariate model including age, sex, and refraction as predictors of angle grade (open or narrow), only age was a significant predictor of angle grade (P=0.004). A large proportion of Chinese-Americans in our study population with glaucoma or glaucoma suspicion had gonioscopically narrow angles. In multivariate analysis, patients with narrow angles were older than those with open angles but did not differ from them in terms of sex or refraction. Continued evaluation of angle closure glaucoma risk among Chinese-Americans is needed.

Bone and Soft Tissue Nasal Angles Discrepancies and Overlying Skin Thickness: A Computed Tomography Study.

PubMed

Alharethy, Sami; Alohali, Sama; Alquniabut, Ibrahim; Jang, Yong Ju

2018-04-11

The aim of this study was to derive the normal values for bone and soft tissue nasal angles as well as the overlying skin thickness and to attempt to determine the correlation between differences in bone and soft tissue angles and overlying skin thickness in Middle Eastern patients. Three-dimensional cephalometric analysis was performed for 100 patients who underwent computed tomography of the paranasal sinuses. The nasofrontal angle, pyramidal angle-nasal root, pyramidal angle-tip of the nasal bone, and overlying skin thickness were measured, and the results were analyzed according to sex, age, and body mass index (BMI). All soft tissue angles were significantly larger than the bone angles, with the mean difference being 11.62°, 30.80°, and 27.05° for the nasofrontal angle (P = 0.000), pyramidal angle-nasal root (P = 0.000), and pyramidal angle-tip of the nasal bone (P = 0.000), respectively. The mean overlying skin thickness was 3.89 ± 1.48 mm at the nasion, 1.16 ± 0.6 mm at the rhinion, and 2.93 ± .97 mm at the nasal tip. Differences in the nasofrontal angle were strongly correlated with the skin thickness at the nasion (P = 0.001). A simple clinical exam of the soft tissue nasal angles does not reflect the underlying bone angles that will be encountered during rhinoplasty. BMI does not influence nasal shape, and rhinoplasty surgery should take into account the ethnic group, age, and sex of the patient. Surgeons should leave a minor skeletal hump at the end of the nasal bone for Middle Eastern patients. This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

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

Yin Yunpeng; Sawin, Herbert H.

The surface roughness evolutions of single crystal silicon, thermal silicon dioxide (SiO{sub 2}), and low dielectric constant film coral in argon plasma have been measured by atomic force microscopy as a function of ion bombardment energy, ion impingement angle, and etching time in an inductively coupled plasma beam chamber, in which the plasma chemistry, ion energy, ion flux, and ion incident angle can be adjusted independently. The sputtering yield (or etching rate) scales linearly with the square root of ion energy at normal impingement angle; additionally, the angular dependence of the etching yield of all films in argon plasma followedmore » the typical sputtering yield curve, with a maximum around 60 deg. -70 deg. off-normal angle. All films stayed smooth after etching at normal angle but typically became rougher at grazing angles. In particular, at grazing angles the rms roughness level of all films increased if more material was removed; additionally, the striation structure formed at grazing angles can be either parallel or transverse to the beam impingement direction, which depends on the off-normal angle. More interestingly, the sputtering caused roughness evolution at different off-normal angles can be qualitatively explained by the corresponding angular dependent etching yield curve. In addition, the roughening at grazing angles is a strong function of the type of surface; specifically, coral suffers greater roughening compared to thermal silicon dioxide.« less

Postoperative Increase in Occiput-C2 Angle Negatively Impacts Subaxial Lordosis after Occipito-Upper Cervical Posterior Fusion Surgery.

PubMed

Inada, Taigo; Furuya, Takeo; Kamiya, Koshiro; Ota, Mitsutoshi; Maki, Satoshi; Suzuki, Takane; Takahashi, Kazuhisa; Yamazaki, Masashi; Aramomi, Masaaki; Mannoji, Chikato; Koda, Masao

2016-08-01

Retrospective case series. To elucidate the impact of postoperative occiput-C2 (O-C2) angle change on subaxial cervical alignment. In the case of occipito-upper cervical fixation surgery, it is recommended that the O-C2 angle should be set larger than the preoperative value postoperatively. The present study included 17 patients who underwent occipito-upper cervical spine (above C4) posterior fixation surgery for atlantoaxial subluxation of various etiologies. Plain lateral cervical radiographs in a neutral position at standing were obtained and the O-C2 angle and subaxial lordosis angle (the angle between the endplates of the lowest instrumented vertebra (LIV) and C7 vertebrae) were measured preoperatively and postoperatively soon after surgery and ambulation and at the final follow-up visit. There was a significant negative correlation between the average postoperative alteration of O-C2 angle (DO-C2) and the average postoperative alteration of subaxial lordosis angle (Dsubaxial lordosis angle) (r=-0.47, p=0.03). There was a negative correlation between DO-C2 and Dsubaxial lordosis angles. This suggests that decrease of mid-to lower-cervical lordosis acts as a compensatory mechanism for lordotic correction between the occiput and C2. In occipito-cervical fusion surgery, care must be taken to avoid excessive O-C2 angle correction because it might induce mid-to-lower cervical compensatory decrease of lordosis.

Study on verifying the angle measurement performance of the rotary-laser system

NASA Astrophysics Data System (ADS)

Zhao, Jin; Ren, Yongjie; Lin, Jiarui; Yin, Shibin; Zhu, Jigui

2018-04-01

An angle verification method to verify the angle measurement performance of the rotary-laser system was developed. Angle measurement performance has a great impact on measuring accuracy. Although there is some previous research on the verification of angle measuring uncertainty for the rotary-laser system, there are still some limitations. High-precision reference angles are used in the study of the method, and an integrated verification platform is set up to evaluate the performance of the system. This paper also probes the error that has biggest influence on the verification system. Some errors of the verification system are avoided via the experimental method, and some are compensated through the computational formula and curve fitting. Experimental results show that the angle measurement performance meets the requirement for coordinate measurement. The verification platform can evaluate the uncertainty of angle measurement for the rotary-laser system efficiently.

Estimation of internal friction angle of subduction zone in northeast of Japan by using seismic focal mechanisms

NASA Astrophysics Data System (ADS)

Miyakawa, A.; Sato, K.; Otsubo, M.

2017-12-01

Physical properties, such as friction angle of the material, is important to understand the interplate earthquake of a subduction zone. Coulomb wedge model (Davis et al., 1983, JGR) is successfully revealed the relationship between a geometry of an accretionary wedge in a subduction zone and the physical properties of the material composing the accretionary wedge (e.g. Dahlen, 1984, JGR). An internal friction angle of the wedge and the frictional strength of the plate boundary fault control the wedge angle according to the Coulomb wedge model. However, the internal friction angle of the wedge and the frictional strength of the plate boundary fault are hard to estimate. Many previous works assumed the internal friction angle of the wedge on the basis of the laboratory experiments. Then, the frictional strength of the plate boundary fault, which is usually most interested, were evaluated from the observed wedge angle and the assumed internal friction angle of the wedge. Consequently, we should be careful of the selection of the internal friction angle of the wedge, otherwise, the uncertain an inappropriate internal friction angle may mislead the frictional strength of the plate boundary fault. In this study, we employed the newly developed technique to evaluate the internal friction angle of the wedge from the earthquake focal mechanisms occurred in the wedge along Japan Trench, northeast Japan. We used 650 earthquake mechanisms determined by NIED, Japan for the stress and friction coefficient inversion. The stress and friction coefficient inversion method is modified to handle the earthquake focal mechanisms from a computerized method to estimate the friction coefficient from the orientation distribution of faults (Sato, 2016, JSG). Finally, we obtained 25 degrees of internal friction angle of the wedge from the inversion. This value of friction angle is lower than usually assumed internal friction angle (30 degrees) (Byerlee, 1978, PAGEOPH). This lower internal friction angle leads to lower frictional strength of plate boundary fault ( 0.35) according to the Coulomb wedge model. These constrained physical parameters can contribute to understanding the interplate earthquake at each subduction zones.

Anterior segment optical coherence tomography parameters in phacomorphic angle closure and mature cataracts.

PubMed

Mansouri, Mohammadreza; Ramezani, Farshid; Moghimi, Sasan; Tabatabaie, Ali; Abdi, Fatemeh; He, Mingguang; Lin, Shan C

2014-10-21

To describe anterior segment optical coherence tomography (AS-OCT) parameters in phacomorphic angle closure eyes, mature cataract eyes, and their fellow eyes, and identify those parameters that could be used to differentiate phacomorphic angle closure eyes from those with mature cataract and no phacomorphic angle closure. In this cross-sectional study, a total of 33 phacomorphic angle closure subjects and 34 control patients with unilateral mature cataracts were enrolled. All patients underwent AS-OCT imaging and A-scan biometry of both eyes. Anterior chamber depth (ACD), anterior chamber area (ACA), iris thickness, iris curvature, lens vault (LV), and angle parameters, including angle opening distance (AOD750) and trabecular-iris space area (TISA750), were measured in qualified images using customized software and compared among eyes with phacomorphic angle closure, mature cataract eyes, and their fellow eyes. There was no significant difference in axial length among the four groups. Phacomorphic angle closure had the smallest angle (AOD750, TISA750) and anterior chamber parameters (ACD, ACA, anterior chamber width) and the greatest LV among the groups. This pattern was similar when comparing fellow eyes of mature cataract patients and fellow eyes of phacomorphic angle closure. Anterior chamber area less than 18.62 mm(2), ACD less than 2.60 mm, LV greater than 532.0 μm, and AOD750 less than 0.218 mm had the highest odds ratios (ORs) for distinguishing fellow eyes of phacomorphic angle closure versus fellow eyes of mature cataracts, with OR values of 9.90, 8.31, 7.91, and 7.91, respectively. Logistic regression showed that ACA less than 18.62 was the major parameter associated with fellow eyes of phacomorphic angle closure (OR = 10.96, P < 0.001). Anterior chamber depth, ACA, AOD750, and LV are powerful indicators in differentiating phacomorphic angle closure eyes from those with mature cataract and their fellow eyes. Copyright 2014 The Association for Research in Vision and Ophthalmology, Inc.

Acetabular-epiphyseal angle and hip dislocation in cerebral palsy: a preliminary study.

PubMed

Alí-Morell, O J; Zurita-Ortega, F; Davó-Jiménez, I; Segura-Biedma, S

To relate, in non-ambulatory subjects with palsy, Reimers' migration percentage with standardized radiological measurements, including the acetabular-epiphyseal angle. Descriptive, observational and transversal study of 15 individuals with cerebral palsy at levels IV and V of the Gross Motor Function Classification System, aged between 3 and 9 years. Radiological measurements of the acetabular index, Hilgenreiner's epiphyseal angle, acetabular-epiphyseal angle, neck-shaft angle and Reimers' migration percentage of each of the hips were performed. Correlations between acetabular index, epiphyseal angle and acetabular-epiphyseal angle were obtained with respect to the Reimers migration percentage. For hips with a migration rate of 15% or less, a positive correlation was observed between acetabular and epiphyseal angles. In our population, the measurement between acetabular and epiphyseal inclination represents the highest association with the hip migration percentage. Copyright © 2018 SERAM. Publicado por Elsevier España, S.L.U. All rights reserved.

Effect of shallow angles on compressive strength of biaxial and triaxial laminates.

PubMed

Jia, Hongli; Yang, Hyun-Ik

2016-01-01

Biaxial (BX) and triaxial (TX) composite laminates with ±45° angled plies have been widely used in wind turbine blades. As the scale of blades increases, BX and TX laminates with shallow-angled plies (i.e. off-axis ply angle <45°) might be utilized for reducing mass and/or improving performance. The compressive properties of shallow-angled BX and TX laminates are critical considering their locations in a wind turbine blade, and therefore in this study, the uniaxial static compression tests were conducted using BX and TX laminates with angled-plies of ±45°, ±35°, and ±25°, for the purpose of evaluation. On the other hand, Mori-Tanaka mean field homogenization method was employed to predict elastic constants of plies in BX and TX laminates involved in tests; linear regression analyses of experimentally measured ply strengths collected from various sources were then performed to estimate strengths of plies in BX and TX laminates; finally, Tsai-Wu, Hashin, and Puck failure criteria were chosen to predict compressive strengths of BX and TX laminates. Comparison between theoretical predictions and test results were carried out to illustrate the effectiveness of each criterion. The compressive strength of BX laminate decreases as ply angle increases, and the trend was successfully predicted by all three failure criteria. For TX laminates, ±35° angled plies rather than ±45° angled plies led to the lowest laminate compressive strength. Hashin and Puck criteria gave good predictions at certain ply angles for TX laminates, but Tsai-Wu criterion was able to capture the unexpected strength variation of TX laminates with ply angle. It was concluded that the transverse tensile stress in 0° plies of TX laminates, which attains its maximum when the off-axis ply angle is 35°, is the dominant factor in failure determination if using Tsai-Wu criterion. This explains the unexpected strength variation of TX laminates with ply angle, and also indicates that proper selection of ply angle is the key to fully utilizing the advantages of shallow-angled laminates.

Wafer scale oblique angle plasma etching

DOEpatents

Burckel, David Bruce; Jarecki, Jr., Robert L.; Finnegan, Patrick Sean

2017-05-23

Wafer scale oblique angle etching of a semiconductor substrate is performed in a conventional plasma etch chamber by using a fixture that supports a multiple number of separate Faraday cages. Each cage is formed to include an angled grid surface and is positioned such that it will be positioned over a separate one of the die locations on the wafer surface when the fixture is placed over the wafer. The presence of the Faraday cages influences the local electric field surrounding each wafer die, re-shaping the local field to be disposed in alignment with the angled grid surface. The re-shaped plasma causes the reactive ions to follow a linear trajectory through the plasma sheath and angled grid surface, ultimately impinging the wafer surface at an angle. The selected geometry of the Faraday cage angled grid surface thus determines the angle at with the reactive ions will impinge the wafer.

Cheaper Synthesis Of Multipole-Brushless-dc-Motor Current

NASA Technical Reports Server (NTRS)

Alhorn, Dean C.; Howard, David E.

1994-01-01

Circuit converts output of single two-phase shaft-angle resolver to that of multi-speed three-phase shaft-angle resolver. Converter circuit applicable to generation of multispeed, multiphase shaft-angle-resolver signals from single two-phase shaft-angle resolver. Combination of converter circuit and single two-phase shaft-angle resolver offer advantages in cost, weight, size, and complexity. Design readily adaptable to two-phase motor.

Wind-Tunnel Investigation of the Low-Speed Static Stability and Control Characteristics of a Model of the Bell MX-776 (RASCAL) in Combined Angle of Attack and Sideslip

NASA Technical Reports Server (NTRS)

Letko, William

1949-01-01

An investigation has been made in the Langley stability tunnel to determine the low-speed static stability and control characteristics of a model of the Bell MX-776. The results show the model to be longitudinally unstable in the angle-of-attack range around zero angle of attack and to become stable at moderate angles of attack. The results of the present investigation agree reasonably well with results obtained in other facilities at low speed. The present pitching-moment results at low Mach numbers also agree reasonably well with unpublished results of tests of the model at supersonic Mach numbers (up to Mach number 1.86). Unpublished results at moderate and high subsonic speeds, however, indicate considerably greater instability at low angles of attack than is indicated by low-speed results. The results of the present tests also showed that the pitching-moment coefficients for angles of attack up to 12deg remained fairly constant with sideslip angle up to 12deg. The elevators tested produced relatively large pitching moments at zero angle of attack but, as the angle of attack was increased, the elevator effectiveness decreased. The rate of decrease of elevator effectiveness with angle of attack was less for 8deg than for 20deg elevator deflection. Therefore although 8deg deflection caused an appreciable change in longitudinal trim angle and trim lift coefficient a deflection of 20deg caused only a small additional increase in trim angle and trim lift coefficient.

Effects of diurnal, lighting, and angle-of-incidence variation on anterior segment optical coherence tomography (AS-OCT) angle metrics.

PubMed

Akil, Handan; Dastiridou, Anna; Marion, Kenneth; Francis, Brian A; Chopra, Vikas

2017-03-23

First reported study to assess the effect of diurnal variation on anterior chamber angle measurements, as well as, to re-test the effects of lighting and angle-of-incidence variation on anterior chamber angle (ACA) measurements acquired by time-domain anterior segment optical coherence tomography (AS-OCT). A total of 30 eyes from 15 healthy, normal subjects underwent anterior chamber imaging using a Visante time-domain AS-OCT according to an IRB-approved protocol. For each eye, the inferior angle was imaged twice in the morning (8 am - 10 am) and then again in the afternoon (3 pm - 5 pm), under light meter-controlled conditions with ambient room lighting 'ON' and lights 'OFF', and at 5° angle of incidence increments. The ACA metrics measured for each eye were: angle opening distance (AOD, measured 500 and 750 μm anterior from scleral spur), the trabecular-iris-space area (TISA, measured 500 and 750 μm anterior from scleral spur), and scleral spur angle. Measurements were performed by masked, certified Reading Center graders using the Visante's Internal Measurement Tool. Differences in measurements between morning and afternoon, lighting variations, and angle of incidence were compared. Mean age of the participants was 31.2 years (range 23-58). Anterior chamber angle metrics did not differ significantly from morning to afternoon imaging, or when the angle of incidence was offset by 5° in either direction away from the inferior angle 6 o'clock position. (p-value 0.13-0.93). Angle metrics at the inferior corneal limbus, 6 o'clock position (IC270), with room lighting 'OFF', showed a significant decrease (p < 0.05) compared to room lighting 'ON'. There does not appear to be significant diurnal variation in AS-OCT parameters in normal individuals, but lighting conditions need to be strictly controlled since variation in lighting led to significant variability in AS-OCT parameters. No changes in ACA parameters were noted by varying the angle-of-incidence, which gives confidence in being able to perform longitudinal studies in approximately the same area (plus/minus 5° of original scan location).

A study of roll attractor and wing rock of delta wings at high angles of attack

NASA Technical Reports Server (NTRS)

Niranjana, T.; Rao, D. M.; Pamadi, Bandu N.

1993-01-01

Wing rock is a high angle of attack dynamic phenomenon of limited cycle motion predominantly in roll. The wing rock is one of the limitations to combat effectiveness of the fighter aircraft. Roll Attractor is the steady state or equilibrium trim angle (phi(sub trim)) attained by the free-to-roll model, held at some angle of attack, and released form rest at a given initial roll (bank) angle (phi(sub O)). Multiple roll attractors are attained at different trim angles depending on initial roll angle. The test facility (Vigyan's low speed wind tunnel) and experimental work is presented here along with mathematical modelling of roll attractor phenomenon and analysis and comparison of predictions with experimental data.

Bioelectrical impedance phase angle relates to function, disease severity and prognosis in stable chronic obstructive pulmonary disease.

PubMed

Maddocks, Matthew; Kon, Samantha S C; Jones, Sarah E; Canavan, Jane L; Nolan, Claire M; Higginson, Irene J; Gao, Wei; Polkey, Michael I; Man, William D-C

2015-12-01

Bioelectrical impedance analysis (BIA) provides a simple method to assess changes in body composition. Raw BIA variables such as phase angle provide direct information on cellular mass and integrity, without the assumptions inherent in estimating body compartments, e.g. fat-free mass (FFM). Phase angle is a strong functional and prognostic marker in many disease states, but data in COPD are lacking. Our aims were to describe the measurement of phase angle in patients with stable COPD and determine the construct and discriminate validity of phase angle by assessing its relationship with established markers of function, disease severity and prognosis. 502 outpatients with stable COPD were studied. Phase angle and FFM by BIA, quadriceps strength (QMVC), 4-m gait speed (4MGS), 5 sit-to-stand time (5STS), incremental shuttle walk (ISW), and composite prognostic indices (ADO, iBODE) were measured. Patients were stratified into normal and low phase angle and FFM index. Phase angle correlated positively with FFM and functional outcomes (r = 0.35-0.66, p < 0.001) and negatively with prognostic indices (r = -0.35 to -0.48, p < 0.001). In regression models, phase angle was independently associated with ISW, ADO and iBODE whereas FFM was removed. One hundred and seventy patients (33.9% [95% CI, 29.9-38.1]) had a low phase angle. Phenotypic characteristics included lower QMVC, ISW, and 4MGS, higher 5STS, ADO and iBODE scores, and more exacerbations and hospital days in past year. The proportion of patients to have died was significantly higher in patients with low phase angle compared to those with normal phase angle (8.2% versus 3.6%, p = 0.02). Phase angle relates to markers of function, disease severity and prognosis in patients with COPD. As a directly measured variable, phase angle offers more useful information than fat-free mass indices. Copyright © 2015 Elsevier Ltd and European Society for Clinical Nutrition and Metabolism. All rights reserved.

Laser-induced breakdown spectra of rock powders at variable ablation and collection angles under Mars-analog conditions

NASA Astrophysics Data System (ADS)

Breves, E. A.; Lepore, K.; Dyar, M. D.; Bender, S. C.; Tokar, R. L.; Boucher, T.

2017-11-01

Laser-induced breakdown spectroscopy has become a popular tool for rapid elemental analysis of geological materials. However, quantitative applications of LIBS are plagued by variability in collected spectra that cannot be attributed to differences in geochemical composition. Even under ideal laboratory conditions, variability in LIBS spectra creates a host of difficulties for quantitative analysis. This is only exacerbated during field work, when both the laser-sample distance and the angle of ablation/collection are constantly changing. A primary goal of this study is to use empirical evidence to provide a more accurate assessment of uncertainty in LIBS-derived element predictions. We hope to provide practical guidance regarding the angles of ablation and collection that can be tolerated without substantially increasing prediction uncertainty beyond that which already exists under ideal laboratory conditions. Spectra were collected from ten geochemically diverse samples at angles of ablation and collection ranging from 0° to ± 60°. Ablation and collection angles were changed independently and simultaneously in order to isolate spectral changes caused by differences in ablation angle from those due to differences in collection angle. Most of the variability in atomic and continuum spectra is attributed to changes in the ablation angle, rather than the collection angle. At higher angles, the irradiance of the laser beam is lower and produces smaller, possibly less dense plasmas. Simultaneous changes in the collection angle do not appear to affect the collected spectra, possibly because smaller plasmas are still within the viewing area of the collection optics, even though this area is reduced at higher collection angles. A key observation is that changes in the magnitude of atomic and total emission are < 5% and 10%, respectively, in spectra collected with the configuration that most closely resembles field measurements (VV) at angles < 20°. In addition, variability in atomic and continuum emission is strongly dependent upon sample composition. Denser, more Fe/Mg-rich rocks exhibited much less variability with changes in ablation and collection angles than Si-rich felsic rocks. Elemental compositions of our variable angle data that were predicted using a much larger but conventionally-collected calibration suite show that accuracy generally suffers when the incidence and collection angles are high. Prediction accuracy (for measurements acquired with varying collection and ablation angles) varies from ± 1.28-1.86 wt% for Al2O3, ± 1.25-1.66 wt% for CaO, ± 1.90-2.21 wt% for Fe2O3T, ± 0.76-0.94 wt% for K2O, ± 2.85-3.61 wt% MgO, ± 0.15-0.17 wt% for MnO, ± 0.68-0.78 wt% for Na2O, ± 0.33-0.42 wt% for TiO2, and ± 2.94-4.34 wt% SiO2. The ChemCam team is using lab data acquired under normal incidence and collection angles to predict the compositions of Mars targets at varying angles. Thus, the increased errors noted in this study for high incidence angle measurements are likely similar to additional, unacknowledged errors on ChemCam results for non-normal targets analyzed on Mars. Optimal quantitative analysis of LIBS spectra must include some knowledge of the angle of ablation and collection so the approximate increase in uncertainty introduced by a departure from normal angles can be accurately reported.

Comparing Gonioscopy With Visante and Cirrus Optical Coherence Tomography for Anterior Chamber Angle Assessment in Glaucoma Patients.

PubMed

Hu, Cindy X; Mantravadi, Anand; Zangalli, Camila; Ali, Mohsin; Faria, Bruno M; Richman, Jesse; Wizov, Sheryl S; Razeghinejad, M Reza; Moster, Marlene R; Katz, L Jay

2016-02-01

The aim of this study was to compare gonioscopy with Visante and Cirrus optical coherence tomography (OCT) for identifying angle structures and the presence of angle closure in patients with glaucoma. A secondary objective was to assess interrater agreement for gonioscopy grading among 3 independent examiners. Gonioscopy grading using Spaeth Classification and determination of angle-closure risk was performed on 1 randomly selected eye for 50 phakic patients. Images of the same eye using both Visante and Cirrus OCT were obtained in both light and dark conditions. Agreement of angle closure among 3 devices and interrater agreement for gonioscopy were determined using Cohen's κ (K) or Kendall's coefficient of concordance (W). Of the 50 patients, 60% were female, 64% were white, and the mean age was 62 years. Angle closure was detected in 18%, 16%, and 48% of quadrants with Visante, Cirrus, and gonioscopy, respectively. The scleral spur was identified in 56% and 50% of quadrants with Visante and Cirrus OCT, respectively. Visante and Cirrus OCT showed moderate agreement in detecting angle closure (K=0.42 light, K=0.53 dark) but slight-to-fair agreement with gonioscopy (Visante K=0.25, Cirrus K=0.15). Gonioscopy demonstrated substantial agreement in angle closure (K=0.65 to 0.68) and angle-closure risk assessment (W=0.83) among 3 examiners. Visante and Cirrus OCT imaging may have limited ability to identify angle closure because of difficulty identifying angle structures. Gonioscopy by well-trained clinicians had remarkably consistent agreement for identifying angle-closure risk.

[Correlation analysis on the disorders of patella-femoral joint and torsional deformity of tibia].

PubMed

Sun, Zhen-Jie; Yuan, Yi; Liu, Rui-Bo

2015-03-01

To reveal the possible mechanism involved in patella-femoral degenerative arthritis (PFDA) in- duced by torsion-deformity of tibia via analyzing the relationship between torsion-deformity of the tibia in patients with PFDA and the disorder of patella-femoral joint under the static and dynamic conditions. From October 2009 to October 2010, 50 patients (86 knees, 24 knees of male patients and 62 knees of female patients) with PFDA were classified as disease group and 16 people (23 knees, 7 knees of males and 16 knees of females) in the control group. The follow indexes were measured: the torsion-angle of tibia on CT scanning imagings, the patella-femoral congruence angle and lateral patella-femoral angle under static and dynamic conditions when the knee bent at 30 degrees of flexion. Based on the measurement results, the relationship between the torsion-deformity of tibias and the disorders of patella-femoral joints in patients with PFDA were analyzed. Finally,the patients were divided into three groups including large torsion-angle group, small torsion-angle group and normal group according to the size of torsion-angle, in order to analyze the relationship between torsion-deformity and disorders of patella-femoral joint, especially under the dynamic conditions. Compared with patients without PFDA, the ones with PFDA had bigger torsion-angle (30.30 ± 7.11)° of tibia, larger patella-femoral congruence angle (13.20 ± 3.94)° and smaller lateral patella-femoral angle (12.30 ± 3.04)°. The congruence angle and lateral patella-femoral angle under static and dynamic conditions had statistical differences respectively in both too-big torsion-angle group and too-small torsion-angle group. The congruence angle and lateral patella-femoral angle under static and dynamic conditions had no statistical differences in normal torsion-angle group. Torsion-deformity of tibia is the main reason for disorder of patella-femoral joint in the patients with PFDA. Torsion-deformity of tibia is always accompanied by instability of patella-femoral joint,especially under the dynamic condition, thus causing PFDA. It can not only provide arrangement information and degenerative condition of patella-femoral joint,but also provide guidance through the analysis on the relationship for better clinical prevention and early treatment of degenerative bone and joint disease.

Light transfer through windows with external condensation

NASA Astrophysics Data System (ADS)

Zhu, Keyong; Li, Shaoling; Pilon, Laurent

2018-03-01

This study investigates systematically light transfer through windows supporting cap-shaped droplets on their external face. The presence of such droplets may have negative effects on the conversion efficiency of solar cells, distorts image quality of lenses, or hinders visibility through windows and windshields. Here, the directional-hemispherical transmittance was predicted by the Monte Carlo ray-tracing method. The droplets were monodisperse or polydisperse randomly distributed on the outside face of optically smooth windows. For nonabsorbing droplets, the diameter and size distribution did not have a significant effect on the window directional-hemispherical transmittance. The latter was nearly independent of contact angle for incident angle θi ≤ 30°. However, the directional-hemispherical transmittance decreased monotonously with increasing incident angle and droplet contact angle for contact angle θc ≤ 70° to reach a minimum at a contact angle θc,min beyond which it increased with increasing contact angle before reaching a plateau at large contact angles. This was attributed to total internal reflection at the back window/air and droplet/air interfaces. For absorbing droplets, the normal-hemispherical transmittance decreased significantly with increasing droplet contact angle, mean diameter, polydispersity, and projected surface area coverage due to strong absorption within the droplets. Moreover, the normal-hemispherical transmittance decreased with increasing contact angle for θc< 90° and remained constant and independent of the droplets' absorption index, mean diameter, and contact angle for θc ≥ 90°. Finally, Analytical expressions for the upper and lower bounds of the normal-hemispherical transmittance as a function of droplet contact angle, optical properties, and projected surface area coverage were derived.

Observational drawing biases are predicted by biases in perception: Empirical support of the misperception hypothesis of drawing accuracy with respect to two angle illusions.

PubMed

Ostrofsky, Justin; Kozbelt, Aaron; Cohen, Dale J

2015-01-01

We tested the misperception hypothesis of drawing errors, which states that drawing accuracy is strongly influenced by the perceptual encoding of a to-be-drawn stimulus. We used a highly controlled experimental paradigm in which nonartist participants made perceptual judgements and drawings of angles under identical stimulus exposure conditions. Experiment 1 examined the isosceles/scalene triangle angle illusion; congruent patterns of bias in the perception and drawing tasks were found for 40 and 60° angles, but not for 20 or 80° angles, providing mixed support for the misperception hypothesis. Experiment 2 examined shape constancy effects with respect to reproductions of single acute or obtuse angles; congruent patterns of bias in the perception and drawing tasks were found across a range of angles from 29 to 151°, providing strong support for the misperception hypothesis. In both experiments, perceptual and drawing biases were positively correlated. These results are largely consistent with the misperception hypothesis, suggesting that inaccurate perceptual encoding of angles is an important reason that nonartists err in drawing angles from observation.

Argon laser peripheral iridoplasty for angle-closure glaucoma in sibilings with weill-marchesani syndrome.

PubMed

Ritch, R; Solomon, L D

1992-01-01

A patient with Weill-Marchesani syndrome and angle-closure glaucoma had persistent appositional closure after laser iridotomy that was unrelieved by topical application of either miotic or cycloplegic agents. Argon laser peripheral iridoplasty successfully opened the angle. The patient's sister also had Weill-Marchesani syndrome and angle closure unrelieved by laser iridotomy. Angle closure in Weill-Marchesani syndrome and the response to laser iridotomy and treatment with either miotic or cycloplegic agents may be complex and depends on the relative proportion of pupillary block as a mechanism underlying the angle closure, the functional status of the zonular apparatus, and the degree of angle crowding by the peripheral iris in the presence or absence of peripheral anterior synechiae.

The hallux valgus angle of the margo medialis pedis as an alternative to the measurement of the metatarsophalangeal hallux valgus angle

PubMed Central

2014-01-01

Background Currently, the metatarsophalangeal angle (hallux valgus angle) is measured based on radiographic images. However, using X-ray examinations for epidemiological or screening purposes would be unethical, especially in children. For this reason it is discussed to measure the hallux valgus angle of the margo medialis pedis (medial border of the foot) documented on foot outline drawings or foot scans. As a first step on the way to prove the validity of those approaches this study assesses the hallux valgus angle measured on the margo medialis pedis based on the same x-ray pictures as the metatarsophalangeal hallux valgus. Methods Radiographic images of the foot were obtained from patients with symptomatic hallux valgus malformation. Twelve sets of contact copies of the 63 originals were made, and were marked and measured according to three different methods, each one performed by two observers and with two repeated measurements. Thus, data sets from 756 individual assessments were entered into the multifactorial statistical analysis. Comparisons were made between the angle of the margo medialis pedis and the metatarsophalangeal angle, which was determined by two different methods. To determine the inter- and intraobserver reliability of the different methods, each assessment was conducted by two independent experts and repeated after a period of several weeks. Results The correlations between the hallux valgus angles determined by the three different methods were all above r = 0.89 (p < 0.001) and thus highly significant. The values obtained by measuring the margo medialis pedis angle, however, were on average 4.8 degrees smaller than the metatarsophalangeal angles. No significant differences were found between the observers. No systematic deviations for any observer between repeated measurements were detected. Conclusions Measurements of the radiographic hallux angle of the margo medialis pedis are reliable and show high correlation with the metatarsophalangeal angle. Because the hallux valgus angles based on margo medialis pedis measurements were slightly but statistically significantly smaller, these measurements should be considered conservative estimates of the metatarsophalangeal angle. Significant differences between hallux valgus angles based on radiographic and non-radiographic material are unlikely. However this question has to be treated in a second stage in detail. PMID:24751201

DYNAMICS OF SELF-GRAVITY WAKES IN DENSE PLANETARY RINGS. I. PITCH ANGLE

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

Michikoshi, Shugo; Kokubo, Eiichiro; Fujii, Akihiko

2015-10-20

We investigate the dynamics of self-gravity wakes in dense planetary rings. In particular, we examine how the pitch angles of self-gravity wakes depend on ring parameters using N-body simulations. We calculate the pitch angles using the two-dimensional autocorrelation function of the ring surface density. We obtain the pitch angles for the inner and outer parts of the autocorrelation function separately. We confirm that the pitch angles are 15°–30° for reasonable ring parameters, which are consistent with previous studies. We find that the inner pitch angle increases with the Saturnicentric distance, while it barely depends on the optical depth and themore » restitution coefficient of ring particles. The increase of the inner pitch angle with the Saturnicentric distance is consistent with the observations of the A ring. The outer pitch angle does not have a clear dependence on any ring parameters and is about 10°–15°. This value is consistent with the pitch angle of spiral arms in collisionless systems.« less

Overdiagnosing of femoroacetabular impingement: correlation between clinical presentation and computed tomography in symptomatic patients☆

PubMed Central

Canella, Richard Prazeres; Adam, Guilherme Pradi; de Castillo, Roberto André Ulhôa; Codonho, Daniel; Ganev, Gerson Gandhi; de Vicenzi, Luiz Fernando

2016-01-01

Objective To correlate the angles between the acetabulum and the proximal femur in symptomatic patients with femoroacetabular impingement (FAI), using computed tomography (CT). Methods We retrospectively evaluated 103 hips from 103 patients, using multislice CT to measure the acetabular age, acetabular version (in its supraequatorial portion and in its middle third), femoral neck version, cervical-diaphyseal and alpha angles and the acetabular depth. For the statistical analysis, we used the Pearson correlation coefficient. Results There were inverse correlations between the following angles: (1) acetabular coverage versus alpha angle (p = 0.019); (2) acetabular version (supraequatorial) versus alpha angle (p = 0.049). For patients with femoral anteversion lower than 15 degrees: (1) acetabular version (supraequatorial) versus alpha angle (p = 0.026); (2) acetabular version (middle third) versus alpha angle (p = 0.02). For patients with acetabular version (supraequatorial) lower than 10 degrees: (1) acetabular version (supraequatorial) versus alpha angle (p = 0.004); (2) acetabular version (middle third) versus alpha angle (p = 0.009). Conclusion There was a statistically significant inverse correlation between the acetabular version and alpha angles (the smaller the acetabular anteversion angle was, the larger the alpha angle was) in symptomatic patients, thus supporting the hypothesis that FAI occurs when cam and pincer findings due to acetabular retroversion are seen simultaneously, and that the latter alone does not cause FAI, which leads to overdiagnosis in these cases. PMID:27069890

Overdiagnosing of femoroacetabular impingement: correlation between clinical presentation and computed tomography in symptomatic patients.

PubMed

Canella, Richard Prazeres; Adam, Guilherme Pradi; de Castillo, Roberto André Ulhôa; Codonho, Daniel; Ganev, Gerson Gandhi; de Vicenzi, Luiz Fernando

2016-01-01

To correlate the angles between the acetabulum and the proximal femur in symptomatic patients with femoroacetabular impingement (FAI), using computed tomography (CT). We retrospectively evaluated 103 hips from 103 patients, using multislice CT to measure the acetabular age, acetabular version (in its supraequatorial portion and in its middle third), femoral neck version, cervical-diaphyseal and alpha angles and the acetabular depth. For the statistical analysis, we used the Pearson correlation coefficient. There were inverse correlations between the following angles: (1) acetabular coverage versus alpha angle (p = 0.019); (2) acetabular version (supraequatorial) versus alpha angle (p = 0.049). For patients with femoral anteversion lower than 15 degrees: (1) acetabular version (supraequatorial) versus alpha angle (p = 0.026); (2) acetabular version (middle third) versus alpha angle (p = 0.02). For patients with acetabular version (supraequatorial) lower than 10 degrees: (1) acetabular version (supraequatorial) versus alpha angle (p = 0.004); (2) acetabular version (middle third) versus alpha angle (p = 0.009). There was a statistically significant inverse correlation between the acetabular version and alpha angles (the smaller the acetabular anteversion angle was, the larger the alpha angle was) in symptomatic patients, thus supporting the hypothesis that FAI occurs when cam and pincer findings due to acetabular retroversion are seen simultaneously, and that the latter alone does not cause FAI, which leads to overdiagnosis in these cases.

Investigations of interpolation errors of angle encoders for high precision angle metrology

NASA Astrophysics Data System (ADS)

Yandayan, Tanfer; Geckeler, Ralf D.; Just, Andreas; Krause, Michael; Asli Akgoz, S.; Aksulu, Murat; Grubert, Bernd; Watanabe, Tsukasa

2018-06-01

Interpolation errors at small angular scales are caused by the subdivision of the angular interval between adjacent grating lines into smaller intervals when radial gratings are used in angle encoders. They are often a major error source in precision angle metrology and better approaches for determining them at low levels of uncertainty are needed. Extensive investigations of interpolation errors of different angle encoders with various interpolators and interpolation schemes were carried out by adapting the shearing method to the calibration of autocollimators with angle encoders. The results of the laboratories with advanced angle metrology capabilities are presented which were acquired by the use of four different high precision angle encoders/interpolators/rotary tables. State of the art uncertainties down to 1 milliarcsec (5 nrad) were achieved for the determination of the interpolation errors using the shearing method which provides simultaneous access to the angle deviations of the autocollimator and of the angle encoder. Compared to the calibration and measurement capabilities (CMC) of the participants for autocollimators, the use of the shearing technique represents a substantial improvement in the uncertainty by a factor of up to 5 in addition to the precise determination of interpolation errors or their residuals (when compensated). A discussion of the results is carried out in conjunction with the equipment used.

Compression member response of steel angle on truss structure with variation of single and double sections

NASA Astrophysics Data System (ADS)

Panjaitan, Arief; Hasibuan, Purwandy

2018-05-01

Implementation of an axial compression load on the steel angle can be found at the various structure such as truss system on telecommunication tower. For telecommunication tower, steel angle section can be suggested as an alternative solution due to its assembling easiness as well as its strength. But, antennas and microwaves installation that keep increases every time on this structure demand reinforcement on each leg of the tower structure. One solution suggested is reinforcement with increasing areas section capacity, where tower leg consisted of single angle section will be reinforced to be double angle section. Regarding this case, this research discussed the behavior of two types of steel angle section: single angle of L.30.30.3 and double angles of 2L.30.30.3. These two sections were designed identically in length (103 cm) and tested by axial compression load. At the first step, compression member together with tension member was formed to be a truss system, where compression and tension member were met at a joint plate. Schematic loading was implemented by giving tension loading on the joint plate until failure of specimens. Experimental work findings showed that implementing double angle sections (103 cm) significantly increased compression capacity of steel angle section up to 118 %.

Anterior Chamber Angle Shape Analysis and Classification of Glaucoma in SS-OCT Images.

PubMed

Ni Ni, Soe; Tian, J; Marziliano, Pina; Wong, Hong-Tym

2014-01-01

Optical coherence tomography is a high resolution, rapid, and noninvasive diagnostic tool for angle closure glaucoma. In this paper, we present a new strategy for the classification of the angle closure glaucoma using morphological shape analysis of the iridocorneal angle. The angle structure configuration is quantified by the following six features: (1) mean of the continuous measurement of the angle opening distance; (2) area of the trapezoidal profile of the iridocorneal angle centered at Schwalbe's line; (3) mean of the iris curvature from the extracted iris image; (4) complex shape descriptor, fractal dimension, to quantify the complexity, or changes of iridocorneal angle; (5) ellipticity moment shape descriptor; and (6) triangularity moment shape descriptor. Then, the fuzzy k nearest neighbor (fkNN) classifier is utilized for classification of angle closure glaucoma. Two hundred and sixty-four swept source optical coherence tomography (SS-OCT) images from 148 patients were analyzed in this study. From the experimental results, the fkNN reveals the best classification accuracy (99.11 ± 0.76%) and AUC (0.98 ± 0.012) with the combination of fractal dimension and biometric parameters. It showed that the proposed approach has promising potential to become a computer aided diagnostic tool for angle closure glaucoma (ACG) disease.

Design of a self-calibration high precision micro-angle deformation optical monitoring scheme

NASA Astrophysics Data System (ADS)

Gu, Yingying; Wang, Li; Guo, Shaogang; Wu, Yun; Liu, Da

2018-03-01

In order to meet the requirement of high precision and micro-angle measurement on orbit, a self-calibrated optical non-contact real-time monitoring device is designed. Within three meters, the micro-angle variable of target relative to measuring basis can be measured in real-time. The range of angle measurement is +/-50'', the angle measurement accuracy is less than 2''. The equipment can realize high precision real-time monitoring the micro-angle deformation, which caused by high strength vibration and shock of rock launching, sun radiation and heat conduction on orbit and so on.

Incident Angle of Saltating Particles in Wind-Blown Sand

PubMed Central

Fu, Lin-Tao; Bo, Tian-Li; Gu, Hai-Hua; Zheng, Xiao-Jing

2013-01-01

Incident angle of saltating particles plays a very important role in aeolian events. In this paper, the incident angles of sand particles near the sand bed were measured in wind tunnel. It reveals that the incident angles range widely from 0° to 180° and thereby the means of angles are larger than published data. Surprisingly, it is found the proportion that angles of 5°–15° occupy is far below previous reports. The measuring height is probably the most important reason for the measurement differences between this study and previous investigations. PMID:23874470

Polarimetric Thermal Imaging

DTIC Science & Technology

2007-03-01

front of a large area blackbody as background. The viewing angle , defined as the angle between surface normal and camera line of sight, was varied by...and polarization angle were derived from the Stokes parameters. The dependence of these polarization characteristics on viewing angle was investigated

Synchronizing Photography For High-Speed-Engine Research

NASA Technical Reports Server (NTRS)

Chun, K. S.

1989-01-01

Light flashes when shaft reaches predetermined angle. Synchronization system facilitates visualization of flow in high-speed internal-combustion engines. Designed for cinematography and holographic interferometry, system synchronizes camera and light source with predetermined rotational angle of engine shaft. 10-bit resolution of absolute optical shaft encoder adapted, and 2 to tenth power combinations of 10-bit binary data computed to corresponding angle values. Pre-computed angle values programmed into EPROM's (erasable programmable read-only memories) to use as angle lookup table. Resolves shaft angle to within 0.35 degree at rotational speeds up to 73,240 revolutions per minute.

High Prevalence of Narrow Angles among Chinese-American Glaucoma and Glaucoma Suspect Patients

PubMed Central

Seider, Michael I; Pekmezci, Melike; Han, Ying; Sandhu, Simi; Kwok, Shiu Y; Lee, Roland Y; Lin, Shan C

2009-01-01

Purpose To evaluate the prevalence of gonioscopically narrow angles in a Chinese-American population with glaucoma or glaucoma suspicion. Patients and Methods Charts from all Chinese-American patients seen in a comprehensive ophthalmology clinic in the Chinatown district of San Francisco in 2002 were reviewed. One eye from each patient with glaucoma or glaucoma suspicion that met inclusion criteria was included (n=108). Data was collected for gender, age, race (self-declared), refraction (spherical equivalent), intraocular pressure (IOP), gonioscopy and vertical cup-to-disk ratio (CDR). Results Sixty percent (n=65) of Chinese-American eyes with glaucoma or glaucoma suspicion had gonioscopically narrow angles (Shaffer grade ≤2 in three or more quadrants). Those with narrow angles were significantly older (P=0.004) than their open angle counterparts, but the two groups did not differ in terms of gender, refraction, IOP or CDR (all, P≥0.071). In a multivariate model including age, gender and refraction as predictors of angle grade (open or narrow), only age was a significant predictor of angle grade (P=0.004). Conclusions A large proportion of Chinese-Americans in our study population with glaucoma or glaucoma suspicion had gonioscopically narrow angles. In multivariate analysis, patients with narrow angles were older than those with open angles but did not differ from them in terms of gender or refraction. Continued evaluation of angle closure glaucoma risk among Chinese-Americans is needed. PMID:19826385

Friction angle measurements on a naturally formed gravel streambed: Implications for critical boundary shear stress

Treesearch

John M. Buffington; William E. Dietrich; James W. Kirchner

1992-01-01

We report the first measurements of friction angles for a naturally formed gravel streambed. For a given test grain size placed on a bed surface, friction angles varied from 10º to over 100º; friction angle distributions can be expressed as a function of test grain size, median bed grain size, and bed sorting parameter. Friction angles decrease with increasing grain...

Postoperative Increase in Occiput–C2 Angle Negatively Impacts Subaxial Lordosis after Occipito–Upper Cervical Posterior Fusion Surgery

PubMed Central

Inada, Taigo; Furuya, Takeo; Kamiya, Koshiro; Ota, Mitsutoshi; Maki, Satoshi; Suzuki, Takane; Takahashi, Kazuhisa; Yamazaki, Masashi; Aramomi, Masaaki; Mannoji, Chikato

2016-01-01

Study Design Retrospective case series. Purpose To elucidate the impact of postoperative occiput–C2 (O–C2) angle change on subaxial cervical alignment. Overview of Literature In the case of occipito–upper cervical fixation surgery, it is recommended that the O–C2 angle should be set larger than the preoperative value postoperatively. Methods The present study included 17 patients who underwent occipito–upper cervical spine (above C4) posterior fixation surgery for atlantoaxial subluxation of various etiologies. Plain lateral cervical radiographs in a neutral position at standing were obtained and the O–C2 angle and subaxial lordosis angle (the angle between the endplates of the lowest instrumented vertebra (LIV) and C7 vertebrae) were measured preoperatively and postoperatively soon after surgery and ambulation and at the final follow-up visit. Results There was a significant negative correlation between the average postoperative alteration of O–C2 angle (DO–C2) and the average postoperative alteration of subaxial lordosis angle (Dsubaxial lordosis angle) (r=–0.47, p=0.03). Conclusions There was a negative correlation between DO–C2 and Dsubaxial lordosis angles. This suggests that decrease of mid-to lower-cervical lordosis acts as a compensatory mechanism for lordotic correction between the occiput and C2. In occipito-cervical fusion surgery, care must be taken to avoid excessive O–C2 angle correction because it might induce mid-to-lower cervical compensatory decrease of lordosis. PMID:27559456

Reliability of Beta angle in assessing true anteroposterior apical base discrepancy in different growth patterns

PubMed Central

Sundareswaran, Shobha; Kumar, Vinay

2015-01-01

Introduction: Beta angle as a skeletal anteroposterior dysplasia indicator is known to be useful in evaluating normodivergent growth patterns. Hence, we compared and verified the accuracy of Beta angle in predicting sagittal jaw discrepancy among subjects with hyperdivergent, hypodivergent and normodivergent growth patterns. Materials and Methods: Lateral cephalometric radiographs of 179 patients belonging to skeletal Classes I, II, and III were further divided into normodivergent, hyperdivergent, and hypodivergent groups based on their vertical growth patterns. Sagittal dysplasia indicators - angle ANB, Wits appraisal, and Beta angle values were measured and tabulated. The perpendicular point of intersection on line CB (Condylion-Point B) in Beta angle was designated as ‘X’ and linear dimension XB was evaluated. Results: Statistically significant increase was observed in the mean values of Beta angle and XB distance in the vertical growth pattern groups of both skeletal Class I and Class II patients thus pushing them toward Class III and Class I, respectively. Conclusions: Beta angle is a reliable indicator of sagittal dysplasia in normal and horizontal patterns of growth. However, vertical growth patterns significantly increased Beta angle values, thus affecting their reliability as a sagittal discrepancy assessment tool. Hence, Beta angle may not be a valid tool for assessment of sagittal jaw discrepancy in patients exhibiting vertical growth patterns with skeletal Class I and Class II malocclusions. Nevertheless, Class III malocclusions having the highest Beta angle values were unaffected. PMID:25810649

Earth Shadows and the SEV Angle of MAP's Lissajous Orbit At L2

NASA Technical Reports Server (NTRS)

Edery, Ariel

2002-01-01

The Microwave Anisotropy Probe (MAP) launched successfully on June 30, 2001 and is presently in a Lissajous orbit about the Sun-Earth libration point L2. To avoid Earth shadows at L2, the Sun-Earth-Vehicle (SEV) angle of MAP has to be greater than 0.5 deg for an extended mission of four years. An equation is derived for the SEV angle in terms of the phase angle, frequencies and amplitudes of the Lissajous. The SEV angle is shown to oscillate with a period of 90.4 days within an amplitude envelope of period 13.9 years. A range of phase angles that avoids shadows is identified. MAP'S present phase angle is within this range and will avoid shadows for approximately 5.8 years.

Optimal angle of needle insertion for fluoroscopy-guided transforaminal epidural injection of L5.

PubMed

Ra, In-Hoo; Min, Woo-Kie

2015-06-01

Unlike other sites, there is difficulty in performing TFESI at the L5-S1 level because the iliac crest is an obstacle to needle placement. The objective of this study was to identify the optimal angle of fluoroscopy for insertion and advancement of a needle during L5 TEFSI. We conducted an observational study of patients undergoing fluoroscopy-guided L5 TFESI in the prone position. A total of 80 patients (40 men and 40 women) with radiating pain of lower limbs were enrolled. During TFESI, we measured the angle at which the L5 vertebral body forms a rectangular shape and compared men and women. Then, we measured area of safe triangle in tilting angle of fluoroscopy from 15° to 35° and compared men and women. The mean cephalocaudal angle, where the vertebral body takes the shape of a rectangle, was 11.0° in men and 13.9° in women (P = 0.007). In men, the triangular area was maximal at 18.3 mm² with an oblique view angle of 25°. In women, the area was maximal at 23.6 mm² with an oblique view angle of 30°. At an oblique view angle of 30° and 35°, the area was significantly greater in women (P < 0.05). When TFESI is performed at the L5 region in the prone position, placement of fluoroscopy at a cephalocaudal angle of 11.0° and an oblique angle of 25° in men and cephalocaudal angle of 13.9° and an oblique angle of 30° in women would be most reasonable. © 2014 World Institute of Pain.

Method and apparatus for controlling pitch and flap angles of a wind turbine

DOEpatents

Deering, Kenneth J [Seattle, WA; Wohlwend, Keith P [Issaquah, WA

2009-05-12

A wind turbine with improved response to wind conditions is provided. Blade flap angle motion is accompanied by a change in pitch angle by an amount defining a pitch/flap coupling ratio. The coupling ratio is non-constant as a function of a flap angle and is preferably a substantially continuous, non-linear function of flap angle. The non-constant coupling ratio can be provided by mechanical systems such as a series of linkages or by configuring electronic or other control systems and/or angle sensors. A link with a movable proximal end advantageously is part of the mechanical system. The system can provide relatively large coupling ratios and relatively large rates of coupling ratio changes especially for near-feather pitches and low flap angles.

Non-contact measurement of rotation angle with solo camera

NASA Astrophysics Data System (ADS)

Gan, Xiaochuan; Sun, Anbin; Ye, Xin; Ma, Liqun

2015-02-01

For the purpose to measure a rotation angle around the axis of an object, a non-contact rotation angle measurement method based on solo camera was promoted. The intrinsic parameters of camera were calibrated using chessboard on principle of plane calibration theory. The translation matrix and rotation matrix between the object coordinate and the camera coordinate were calculated according to the relationship between the corners' position on object and their coordinates on image. Then the rotation angle between the measured object and the camera could be resolved from the rotation matrix. A precise angle dividing table (PADT) was chosen as the reference to verify the angle measurement error of this method. Test results indicated that the rotation angle measurement error of this method did not exceed +/- 0.01 degree.

Automated analysis of angle closure from anterior chamber angle images.

PubMed

Baskaran, Mani; Cheng, Jun; Perera, Shamira A; Tun, Tin A; Liu, Jiang; Aung, Tin

2014-10-21

To evaluate a novel software capable of automatically grading angle closure on EyeCam angle images in comparison with manual grading of images, with gonioscopy as the reference standard. In this hospital-based, prospective study, subjects underwent gonioscopy by a single observer, and EyeCam imaging by a different operator. The anterior chamber angle in a quadrant was classified as closed if the posterior trabecular meshwork could not be seen. An eye was classified as having angle closure if there were two or more quadrants of closure. Automated grading of the angle images was performed using customized software. Agreement between the methods was ascertained by κ statistic and comparison of area under receiver operating characteristic curves (AUC). One hundred forty subjects (140 eyes) were included, most of whom were Chinese (102/140, 72.9%) and women (72/140, 51.5%). Angle closure was detected in 61 eyes (43.6%) with gonioscopy in comparison with 59 eyes (42.1%, P = 0.73) using manual grading, and 67 eyes (47.9%, P = 0.24) with automated grading of EyeCam images. The agreement for angle closure diagnosis between gonioscopy and both manual (κ = 0.88; 95% confidence interval [CI), 0.81-0.96) and automated grading of EyeCam images was good (κ = 0.74; 95% CI, 0.63-0.85). The AUC for detecting eyes with gonioscopic angle closure was comparable for manual and automated grading (AUC 0.974 vs. 0.954, P = 0.31) of EyeCam images. Customized software for automated grading of EyeCam angle images was found to have good agreement with gonioscopy. Human observation of the EyeCam images may still be needed to avoid gross misclassification, especially in eyes with extensive angle closure. Copyright 2014 The Association for Research in Vision and Ophthalmology, Inc.

{l_angle}110{r_angle} dendrite growth in aluminum feathery grains

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

Henry, S.; Rappaz, M.; Jarry, P.

1998-11-01

Automatic indexing of electron backscattered diffraction patterns, scanning electron microscopy, and optical microscopy observations have been carried out on aluminum-magnesium-silicon, aluminum-copper, and aluminum-silicon alloys directionally solidified or semicontinuously cast using the direct chill casting process. From these combined observations, it is shown that the feathery grains are made of {l_angle}110{r_angle} primary dendrite trunks (e.g., [011{bar 1}]) split in their centers by a coherent (111) twin plane. The average spacing of the dendrite trunks in the twin plane (about 10 to 20 {micro}m) is typically one order of magnitude smaller than that separating successive rows of trunks (or twin planes). Themore » [011{bar 1}] orientation of these trunks is close to the thermal gradient direction (typically within 15 deg)--a feature probably resulting from a growth competition mechanism similar to that occurring during normal <100> columnar dendrite growth. On both sides of these trunks, secondary dendrite arms also grow along {l_angle}110{r_angle} directions. Their impingement creates wavy noncoherent twin boundaries between the coherent twin planes. In the twin plane, evidence is shown that {l_angle}110{r_angle} branching mechanisms lead to the propagation of the twinned regions, to the regular arrangement of the primary dendrite trunks along a [{bar 2}11] direction, and to coherent planar twin boundaries. From these observations, it is concluded that the feathery grains are probably the result of a change from a normal <100> to a {l_angle}110{r_angle} surface tension/attachment kinetics anisotropy growth mode. Finally, the proposed mechanisms of leathery grain growth are further supported by the observation of {l_angle}110{r_angle} dendrite growth morphologies in thin aluminum-zinc coatings.« less

Characteristics of fractures in crystalline bedrock determined by surface and borehole geophysical surveys, eastern surplus superfund site, Meddybemps, Maine

USGS Publications Warehouse

Hansen, Bruce P.; Stone, Janet Radway; Lane, John W.

1999-01-01

Surface and borehole geophysical methods were used to determine fracture orientation in crystalline bedrock at the Eastern Surplus Superfund Site in Meddybemps, Maine. Fracture-orientation information is needed to address concerns about the fate of contaminants in ground water at the site. Azimuthal square-array resistivity surveys were conducted at 3 locations at the site, borehole-acoustic televiewer and borehole-video logs were collected in 10 wells, and single-hole directional radar surveys were conducted in 9 wells. Borehole-video logs were used to supplement the results of other geophysical techniques and are not described in this report. Analysis of azimuthal square-array resistivity data indicated that high-angle fracturing generally strikes northeast-southwest at the three locations. Borehole-acoustic televiewer logs detected one prominent low-angle and two prominent high-angle fracture sets. The low-angle fractures strike generally north-northeast and dip about 20 degrees west-northwest. One high-angle fracture set strikes north-northeast and dips east-southeast; the other high-angle set strikes east-northeast and dips south-southeast. Single-hole directional radar surveys identified two prominent fracture sets: a low-angle set striking north-northeast, dipping west-northwest; and a high-angle fracture set striking north-northeast, dipping east-southeast. Two additional high-angle fracture sets are defined weakly, one striking east-west, dipping north; and a second striking east-west, dipping south. Integrated results from all of the geophysical surveys indicate the presence of three primary fracture sets. A low-angle set strikes north-northeast and dips west-northwest. Two high-angle sets strike north-northeast and east-northeast and dip east-southeast and south-southeast. Statistical correction of the fracture data for orientation bias indicates that high-angle fractures are more numerous than observed in the data but are still less numerous than the low-angle fractures. The orientation and distribution of water-yielding fractures sets were determined by correlating the fracture data from this study with previously collected borehole-flowmeter data. The water-yielding fractures are generally within the three prominent fracture sets observed for the total fracture population. The low-angle water-yielding fractures primarily strike north-northeast to west-northwest and dip west-northwest to south-southwest. Most of the high-angle water-yielding fractures strike either north-northeast or east-west and dip east-southeast or south. The spacing between water-yielding fractures varies but the probable average spacing is estimated to be 30 feet for low-angle fractures; 27 feet for the east-southeast dipping, high-angle fractures; and 43 feet for the south-southeast dipping, high-angle fractures. The median estimated apparent transmissivity of individual water-yielding fractures or fracture zones was 0.3 feet squared per day and ranged from 0.01 to 382 feet squared per day. Ninety-five percent of the water-yielding fractures or fracture zones had an estimated apparent transmissivity of 19.5 feet squared per day or less. The orientation, spacing, and hydraulic properties of water-yielding fractures identified during this study can be used to help estimate recharge, flow, and discharge of ground water contaminants. High-angle fractures provide vertical pathways for ground water to enter the bedrock, interconnections between low-angle fractures, and, subsequently, pathways for water flow within the bedrock along fracture planes. Low-angle fractures may allow horizontal ground-water flow in all directions. The orientation of fracturing and the hydraulic properties of each fracture set strongly affect changes in ground-water flow under stress (pumping) conditions.

Surface morphology and electrical properties of Au/Ni/ Left-Pointing-Angle-Bracket C Right-Pointing-Angle-Bracket /n-Ga{sub 2}O{sub 3}/p-GaSe Left-Pointing-Angle-Bracket KNO{sub 3} Right-Pointing-Angle-Bracket hybrid structures fabricated on the basis of a layered semiconductor with nanoscale ferroelectric inclusions

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

Bakhtinov, A. P., E-mail: chimsp@ukrpost.ua; Vodopyanov, V. N.; Netyaga, V. V.

2012-03-15

Features of the formation of Au/Ni/ Left-Pointing-Angle-Bracket C Right-Pointing-Angle-Bracket /n-Ga{sub 2}O{sub 3} hybrid nanostructures on a Van der Waals surface (0001) of 'layered semiconductor-ferroelectric' composite nanostructures (p-GaSe Left-Pointing-Angle-Bracket KNO{sub 3} Right-Pointing-Angle-Bracket ) are studied using atomic-force microscopy. The room-temperature current-voltage characteristics and the dependence of the impedance spectrum of hybrid structures on a bias voltage are studied. The current-voltage characteristic includes a resonance peak and a portion with negative differential resistance. The current attains a maximum at a certain bias voltage, when electric polarization switching in nanoscale three-dimensional inclusions in the layered GaSe matrix occurs. In the high-frequency region (fmore » > 10{sup 6} Hz), inductive-type impedance (a large negative capacitance of structures, {approx}10{sup 6} F/mm{sup 2}) is detected. This effect is due to spinpolarized electron transport in a series of interconnected semiconductor composite nanostructures with multiple p-GaSe Left-Pointing-Angle-Bracket KNO{sub 3} Right-Pointing-Angle-Bracket quantum wells and a forward-biased 'ferromagnetic metal-semiconductor' polarizer (Au/Ni/ Left-Pointing-Angle-Bracket C Right-Pointing-Angle-Bracket /n{sup +}-Ga{sub 2}O{sub 3}/n-Ga{sub 2}O{sub 3}). A shift of the maximum (current hysteresis) is detected in the current-voltage characteristics for various directions of the variations in bias voltage.« less

Kinematics of reflections in subsurface offset and angle-domain image gathers

NASA Astrophysics Data System (ADS)

Dafni, Raanan; Symes, William W.

2018-05-01

Seismic migration in the angle-domain generates multiple images of the earth's interior in which reflection takes place at different scattering-angles. Mechanically, the angle-dependent reflection is restricted to happen instantaneously and at a fixed point in space: Incident wave hits a discontinuity in the subsurface media and instantly generates a scattered wave at the same common point of interaction. Alternatively, the angle-domain image may be associated with space-shift (regarded as subsurface offset) extended migration that artificially splits the reflection geometry. Meaning that, incident and scattered waves interact at some offset distance. The geometric differences between the two approaches amount to a contradictory angle-domain behaviour, and unlike kinematic description. We present a phase space depiction of migration methods extended by the peculiar subsurface offset split and stress its profound dissimilarity. In spite of being in radical contradiction with the general physics, the subsurface offset reveals a link to some valuable angle-domain quantities, via post-migration transformations. The angle quantities are indicated by the direction normal to the subsurface offset extended image. They specifically define the local dip and scattering angles if the velocity at the split reflection coordinates is the same for incident and scattered wave pairs. Otherwise, the reflector normal is not a bisector of the opening angle, but of the corresponding slowness vectors. This evidence, together with the distinguished geometry configuration, fundamentally differentiates the angle-domain decomposition based on the subsurface offset split from the conventional decomposition at a common reflection point. An asymptotic simulation of angle-domain moveout curves in layered media exposes the notion of split versus common reflection point geometry. Traveltime inversion methods that involve the subsurface offset extended migration must accommodate the split geometry in the inversion scheme for a robust and successful convergence at the optimal velocity model.

Omni-Directional Viewing-Angle Switching through Control of the Beam Divergence Angle in a Liquid Crystal Panel

NASA Astrophysics Data System (ADS)

Baek, Jong-In; Kim, Ki-Han; Kim, Jae Chang; Yoon, Tae-Hoon

2010-01-01

This paper proposes a method of omni-directional viewing-angle switching by controlling the beam diverging angle (BDA) in a liquid crystal (LC) panel. The LCs aligned randomly by in-cell polymer structures diffuse the collimated backlight for the bright state of the wide viewing-angle mode. We align the LCs homogeneously by applying an in-plane field for the narrow viewing-angle mode. By doing this the scattering is significantly reduced so that the small BDA is maintained as it passes through the LC layer. The dark state can be obtained by aligning the LCs homeotropically with a vertical electric field. We demonstrated experimentally the omni-directional switching of the viewing-angle, without an additional panel or backlighting system.

Biomechanical effects of humeral neck-shaft angle and subscapularis integrity in reverse total shoulder arthroplasty.

PubMed

Oh, Joo Han; Shin, Sang-Jin; McGarry, Michelle H; Scott, Jonathan H; Heckmann, Nathanael; Lee, Thay Q

2014-08-01

The variability in functional outcomes and the occurrence of scapular notching and instability after reverse total shoulder arthroplasty remain problems. The objectives of this study were to measure the effect of reverse humeral component neck-shaft angle on impingement-free range of motion, abduction moment, and anterior dislocation force and to evaluate the effect of subscapularis loading on dislocation force. Six cadaveric shoulders were tested with 155°, 145°, and 135° reverse shoulder humeral neck-shaft angles. The adduction angle at which bone contact occurred and the internal and external rotational impingement-free range of motion angles were measured. Glenohumeral abduction moment was measured at 0° and 30° of abduction, and anterior dislocation forces were measured at 30° of internal rotation, 0°, and 30° of external rotation with and without subscapularis loading. Adduction deficit angles for 155°, 145°, and 135° neck-shaft angle were 2° ± 5° of abduction, 7° ± 4° of adduction, and 12° ± 2° of adduction (P < .05). Impingement-free angles of humeral rotation and abduction moments were not statistically different between the neck-shaft angles. The anterior dislocation force was significantly higher for the 135° neck-shaft angle at 30° of external rotation and significantly higher for the 155° neck-shaft angle at 30° of internal rotation (P < .01). The anterior dislocation forces were significantly higher when the subscapularis was loaded (P < .01). The 155° neck-shaft angle was more prone to scapular bone contact during adduction but was more stable at the internally rotated position, which was the least stable humeral rotation position. Subscapularis loading gave further anterior stability with all neck-shaft angles at all positions. Published by Mosby, Inc.

Effect of placement angle on the stability of loaded titanium microscrews in beagle jaws.

PubMed

Xu, Zhenrui; Wu, Yeke; Zhao, Lixing; Zhou, Yuqiao; Wei, Xing; Tang, Na; Feng, Xiaoxia; Tang, Tian; Zhao, Zhihe

2013-07-01

To evaluate the effect of insertion angle on stability of loaded titanium microscrews in beagle jaws. Forty-eight microscrews were inserted at four different angles (30°, 50°, 70°, and 90°) into the intraradicular zones of the mandibular first molars and third premolars of 12 beagles and immediately loaded with a force of 2 N for 8 weeks. Microcomputed tomography (micro-CT) and biomechanical pull-out tests were used to assess osseointegration of the interface. All micro-CT parameters and maximum pull-out force (FMAX) of the microscrews were affected by insertion angles of microscrews. Higher micro-CT parameters and FMAX were seen for implants inserted at angles between 50° and 70° (P < .05). Excessive oblique and vertical insertion angles resulted in reduced stability (P < .05). An insertion angle of 50° to 70° is more favorable than excessive oblique or vertical angles to achieve stability of microscrews.

The influence of spray properties on intranasal deposition.

PubMed

Foo, Mow Yee; Cheng, Yung-Sung; Su, Wei-Chung; Donovan, Maureen D

2007-01-01

While numerous devices, formulations, and spray characteristics have been shown to influence nasal deposition efficiency, few studies have attempted to identify which of these interacting factors plays the greatest role in nasal spray deposition. The deposition patterns of solutions with a wide range of surface tensions and viscosities were measured using an MRI-derived nasal cavity replica. The resulting spray plumes had angles between 29 degrees and 80 degrees and contained droplet sizes (D(v50)) from 37-157 microm. Each formulation contained rhodamine 590 as a fluorescent marker for detection. Administration angles of 30 degrees , 40 degrees , or 50 degrees above horizontal were tested to investigate the role of user technique on nasal deposition. The amount of spray deposited within specific regions of the nasal cavity was determined by disassembling the replica and measuring the amount of rhodamine retained in each section. Most of the spray droplets were deposited onto the anterior region of the model, but sprays with small plume angles were capable of reaching the turbinate region with deposition efficiencies approaching 90%. Minimal dependence on droplet size, viscosity, or device was observed. Changes in inspiratory flow rate (0-60 L/min) had no significant effect on turbinate deposition efficiency. Both plume angle and administration angle were found to be important factors in determining deposition efficiency. For administration angles of 40 degrees or 50 degrees , maximal turbinate deposition efficiency (30-50%) occurred with plume angles of 55-65 degrees , whereas a 30 degrees administration angle gave an approximately 75% deposition efficiency for similar plume angles. Deposition efficiencies of approximately 90% could be achieved with plume angles <30 degrees using 30 degrees administration angles. Both the plume angle and administration angle are critical factors in determining deposition efficiency, while many other spray parameters, including particle size, have relatively minor influences on deposition within the nasal cavity.

The Shank-to-Vertical-Angle as a parameter to evaluate tuning of Ankle-Foot Orthoses.

PubMed

Kerkum, Yvette L; Houdijk, Han; Brehm, Merel-Anne; Buizer, Annemieke I; Kessels, Manon L C; Sterk, Arjan; van den Noort, Josien C; Harlaar, Jaap

2015-09-01

The effectiveness of an Ankle-Foot Orthosis footwear combination (AFO-FC) may be partly dependent on the alignment of the ground reaction force with respect to lower limb joint rotation centers, reflected by joint angles and moments. Adjusting (i.e. tuning) the AFO-FC's properties could affect this alignment, which may be guided by monitoring the Shank-to-Vertical-Angle. This study aimed to investigate whether the Shank-to-Vertical-Angle during walking responds to variations in heel height and footplate stiffness, and if this would reflect changes in joint angles and net moments in healthy adults. Ten subjects walked on an instrumented treadmill and performed six trials while walking with bilateral rigid Ankle-Foot Orthoses. The AFO-FC heel height was increased, aiming to impose a Shank-to-Vertical-Angle of 5°, 11° and 20°, and combined with a flexible or stiff footplate. For each trial, the Shank-to-Vertical-Angle, joint flexion-extension angles and net joint moments of the right leg at midstance were averaged over 25 gait cycles. The Shank-to-Vertical-Angle significantly increased with increasing heel height (p<0.001), resulting in an increase in knee flexion angle and internal knee extensor moment (p<0.001). The stiff footplate reduced the effect of heel height on the internal knee extensor moment (p=0.030), while the internal ankle plantar flexion moment increased (p=0.035). Effects of heel height and footplate stiffness on the hip joint were limited. Our results support the potential to use the Shank-to-Vertical-Angle as a parameter to evaluate AFO-FC tuning, as it is responsive to changes in heel height and reflects concomitant changes in the lower limb angles and moments. Copyright © 2015 Elsevier B.V. All rights reserved.

Geometry and evolution of low-angle normal faults (LANF) within a Cenozoic high-angle rift system, Thailand: Implications for sedimentology and the mechanisms of LANF development

NASA Astrophysics Data System (ADS)

Morley, Chris K.

2009-10-01

At least eight examples of large (5-35 km heave), low-angle normal faults (LANFs, 20°-30° dip) occur in the Cenozoic rift basins of Thailand and laterally pass into high-angle extensional fault systems. Three large-displacement LANFs are found in late Oligocene-Miocene onshore rift basins (Suphan Buri, Phitsanulok, and Chiang Mai basins), they have (1) developed contemporaneous with, or after the onset of, high-angle extension, (2) acted as paths for magma and associated fluids, and (3) impacted sedimentation patterns. Displacement on low-angle faults appears to be episodic, marked by onset of lacustrine conditions followed by axial progradation of deltaic systems that infilled the lakes during periods of low or no displacement. The Chiang Mai LANF is a low-angle (15°-25°), high-displacement (15-35 km heave), ESE dipping LANF immediately east of the late early Miocene Doi Inthanon and Doi Suthep metamorphic core complexes. Early Cenozoic transpressional crustal thickening followed by the northward motion of India coupled with Burma relative to east Burma and Thailand (˜40-30 Ma) caused migmatization and gneiss dome uplift in the late Oligocene of the core complex region, followed by LANF activity. LANF displacement lasted 4-6 Ma during the early Miocene and possibly transported a late Oligocene-early Miocene high-angle rift system 35 km east. Other LANFs in Thailand have lower displacements and no associated metamorphic core complexes. The three LANFs were initiated as low-angle faults, not by isostatic rotation of high-angle faults. The low-angle dips appear to follow preexisting low-angle fabrics (thrusts, shear zones, and other low-angle ductile foliations) predominantly developed during Late Paleozoic and early Paleogene episodes of thrusting and folding.

Precision determination of electron scattering angle by differential nuclear recoil energy method

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

Liyanage, N.; Saenboonruang, K.

2015-12-01

The accurate determination of the scattered electron angle is crucial to electron scattering experiments, both with open-geometry large-acceptance spectrometers and ones with dipole-type magnetic spectrometers for electron detection. In particular, for small central-angle experiments using dipole-type magnetic spectrometers, in which surveys are used to measure the spectrometer angle with respect to the primary electron beam, the importance of the scattering angle determination is emphasized. However, given the complexities of large experiments and spectrometers, the accuracy of such surveys is limited and insufficient to meet demands of some experiments. In this article, we present a new technique for determination of themore » electron scattering angle based on an accurate measurement of the primary beam energy and the principle of differential nuclear recoil. This technique was used to determine the scattering angle for several experiments carried out at the Experimental Hall A, Jefferson Lab. Results have shown that the new technique greatly improved the accuracy of the angle determination compared to surveys.« less

Precision Determination of Electron Scattering Angle by Differential Nuclear Recoil Energy Method

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

Liyanage, Nilanga; Saenboonruang, Kiadtisak

2015-09-01

The accurate determination of the scattered electron angle is crucial to electron scattering experiments, both with open-geometry large-acceptance spectrometers and ones with dipole-type magnetic spectrometers for electron detection. In particular, for small central-angle experiments using dipole-type magnetic spectrometers, in which surveys are used to measure the spectrometer angle with respect to the primary electron beam, the importance of the scattering angle determination is emphasized. However, given the complexities of large experiments and spectrometers, the accuracy of such surveys is limited and insufficient to meet demands of some experiments. In this article, we present a new technique for determination of themore » electron scattering angle based on an accurate measurement of the primary beam energy and the principle of differential nuclear recoil. This technique was used to determine the scattering angle for several experiments carried out at the Experimental Hall A, Jefferson Lab. Results have shown that the new technique greatly improved the accuracy of the angle determination compared to surveys.« less

Effect of knee angle on neuromuscular assessment of plantar flexor muscles: A reliability study

PubMed Central

Cornu, Christophe; Jubeau, Marc

2018-01-01

Introduction This study aimed to determine the intra- and inter-session reliability of neuromuscular assessment of plantar flexor (PF) muscles at three knee angles. Methods Twelve young adults were tested for three knee angles (90°, 30° and 0°) and at three time points separated by 1 hour (intra-session) and 7 days (inter-session). Electrical (H reflex, M wave) and mechanical (evoked and maximal voluntary torque, activation level) parameters were measured on the PF muscles. Intraclass correlation coefficients (ICC) and coefficients of variation were calculated to determine intra- and inter-session reliability. Results The mechanical measurements presented excellent (ICC>0.75) intra- and inter-session reliabilities regardless of the knee angle considered. The reliability of electrical measurements was better for the 90° knee angle compared to the 0° and 30° angles. Conclusions Changes in the knee angle may influence the reliability of neuromuscular assessments, which indicates the importance of considering the knee angle to collect consistent outcomes on the PF muscles. PMID:29596480

A contact angle hysteresis model based on the fractal structure of contact line.

PubMed

Wu, Shuai; Ma, Ming

2017-11-01

Contact angle is one of the most popular concept used in fields such as wetting, transport and microfludics. In practice, different contact angles such as equilibrium, receding and advancing contact angles are observed due to hysteresis. The connection among these contact angles is important in revealing the chemical and physical properties of surfaces related to wetting. Inspired by the fractal structure of contact line, we propose a single parameter model depicting the connection of the three angles. This parameter is decided by the fractal structure of the contact line. The results of this model agree with experimental observations. In certain cases, it can be reduced to other existing models. It also provides a new point of view in understanding the physical nature of the contact angle hysteresis. Interestingly, some counter-intuitive phenomena, such as the binary receding angles, are indicated in this model, which are waited to be validated by experiments. Copyright © 2017 Elsevier Inc. All rights reserved.

RaptorX-Angle: real-value prediction of protein backbone dihedral angles through a hybrid method of clustering and deep learning.

PubMed

Gao, Yujuan; Wang, Sheng; Deng, Minghua; Xu, Jinbo

2018-05-08

Protein dihedral angles provide a detailed description of protein local conformation. Predicted dihedral angles can be used to narrow down the conformational space of the whole polypeptide chain significantly, thus aiding protein tertiary structure prediction. However, direct angle prediction from sequence alone is challenging. In this article, we present a novel method (named RaptorX-Angle) to predict real-valued angles by combining clustering and deep learning. Tested on a subset of PDB25 and the targets in the latest two Critical Assessment of protein Structure Prediction (CASP), our method outperforms the existing state-of-art method SPIDER2 in terms of Pearson Correlation Coefficient (PCC) and Mean Absolute Error (MAE). Our result also shows approximately linear relationship between the real prediction errors and our estimated bounds. That is, the real prediction error can be well approximated by our estimated bounds. Our study provides an alternative and more accurate prediction of dihedral angles, which may facilitate protein structure prediction and functional study.

Predictors of Intraocular Pressure After Phacoemulsification in Primary Open-Angle Glaucoma Eyes with Wide Versus Narrower Angles (An American Ophthalmological Society Thesis)

PubMed Central

Lin, Shan C.; Masis, Marisse; Porco, Travis C.; Pasquale, Louis R.

2017-01-01

Purpose To assess if narrower-angle status and anterior segment optical coherence tomography (AS-OCT) parameters can predict intraocular pressure (IOP) drop in primary open-angle glaucoma (POAG) patients after cataract surgery. Methods This was a prospective case series of consecutive cataract surgery patients with POAG and no peripheral anterior synechiae (PAS) using a standardized postoperative management protocol. Preoperatively, patients underwent gonioscopy and AS-OCT. The same glaucoma medication regimen was resumed by 1 month. Potential predictors of IOP reduction included narrower-angle status by gonioscopy and angle-opening distance (AOD500) as well as other AS-OCT parameters. Mixed-effects regression adjusted for use of both eyes and other potential confounders. Results We enrolled 66 eyes of 40 glaucoma patients. The IOP reduction at 1 year was 4.2±3 mm Hg (26%, P<.001) in the narrower-angle group vs 2.2±3 mm Hg (14%, P<.001) in the wide-angle group (P=.027 for difference), as classified by gonioscopy. By AOD500 classification, the narrower-angle group had 3.4±3 mm Hg (21%, P<.001) reduction vs 2.5±3 mm Hg (16%, P<.001) in the wide-angle group (P=.031 for difference). When the entire cohort was assessed, iris thickness, iris area, and lens vault were correlated with increasing IOP reduction at 1 year (P<.05 for all). Conclusions In POAG eyes, cataract surgery lowered IOP to a greater degree in the narrower-angle group than in the wide-angle group, and parameters relating to iris thickness and area, as well as lens vault, were correlated with IOP reduction. These findings can guide ophthalmologists in their selection of cataract surgery as a potential management option. PMID:29147104

Predictors of Intraocular Pressure After Phacoemulsification in Primary Open-Angle Glaucoma Eyes with Wide Versus Narrower Angles (An American Ophthalmological Society Thesis).

PubMed

Lin, Shan C; Masis, Marisse; Porco, Travis C; Pasquale, Louis R

2017-08-01

To assess if narrower-angle status and anterior segment optical coherence tomography (AS-OCT) parameters can predict intraocular pressure (IOP) drop in primary open-angle glaucoma (POAG) patients after cataract surgery. This was a prospective case series of consecutive cataract surgery patients with POAG and no peripheral anterior synechiae (PAS) using a standardized postoperative management protocol. Preoperatively, patients underwent gonioscopy and AS-OCT. The same glaucoma medication regimen was resumed by 1 month. Potential predictors of IOP reduction included narrower-angle status by gonioscopy and angle-opening distance (AOD500) as well as other AS-OCT parameters. Mixed-effects regression adjusted for use of both eyes and other potential confounders. We enrolled 66 eyes of 40 glaucoma patients. The IOP reduction at 1 year was 4.2±3 mm Hg (26%, P <.001) in the narrower-angle group vs 2.2±3 mm Hg (14%, P <.001) in the wide-angle group ( P =.027 for difference), as classified by gonioscopy. By AOD500 classification, the narrower-angle group had 3.4±3 mm Hg (21%, P <.001) reduction vs 2.5±3 mm Hg (16%, P <.001) in the wide-angle group ( P =.031 for difference). When the entire cohort was assessed, iris thickness, iris area, and lens vault were correlated with increasing IOP reduction at 1 year ( P <.05 for all). In POAG eyes, cataract surgery lowered IOP to a greater degree in the narrower-angle group than in the wide-angle group, and parameters relating to iris thickness and area, as well as lens vault, were correlated with IOP reduction. These findings can guide ophthalmologists in their selection of cataract surgery as a potential management option.

Normal Q-angle in an adult Nigerian population.

PubMed

Omololu, Bade B; Ogunlade, Olusegun S; Gopaldasani, Vinod K

2009-08-01

The Q-angle has been studied among the adult Caucasian population with the establishment of reference values. Scientists are beginning to accept the concept of different human races. Physical variability exists between various African ethnic groups and Caucasians as exemplified by differences in anatomic features such as a flat nose compared with a pointed nose, wide rather than narrow faces, and straight rather than curly hair. Therefore, we cannot assume the same Q-angle values will be applicable to Africans and Caucasians. We established a baseline reference value for normal Q-angles among asymptomatic Nigerian adults. The Q-angles of the left and right knees were measured using a goniometer in 477 Nigerian adults (354 males; 123 females) in the supine and standing positions. The mean Q-angles for men were 10.7 degrees +/- 2.2 degrees in the supine position and 12.3 degrees +/- 2.2 degrees in the standing position in the right knee. The left knee Q-angles in men were 10.5 degrees +/- 2.6 degrees in the supine position and 11.7 degrees +/- 2.8 degrees in the standing position. In women, the mean Q-angles for the right knee were 21 degrees +/- 4.8 degrees in the supine position and 22.8 degrees +/- 4.7 degrees in the standing position. The mean Q-angles for the left knee in women were 20.9 degrees +/- 4.6 degrees in the supine position and 22.7 degrees +/- 4.6 degrees in the standing position. We observed a difference in Q-angles in the supine and standing positions for all participants. The Q-angle in adult Nigerian men is comparable to that of adult Caucasian men, but the Q-angle of Nigerian women is greater than that of their Caucasian counterparts.

Effect of acetabular cup abduction angle on wear of ultrahigh-molecular-weight polyethylene in hip simulator testing.

PubMed

Korduba, Laryssa A; Essner, Aaron; Pivec, Robert; Lancin, Perry; Mont, Michael A; Wang, Aiguo; Delanois, Ronald E

2014-10-01

The effect of acetabular component positioning on the wear rates of metal-on-polyethylene articulations has not been extensively studied. Placement of acetabular cups at abduction angles of more than 40° has been noted as a possible reason for early failure caused by increased wear. We conducted a study to evaluate the effects of different acetabular cup abduction angles on polyethylene wear rate, wear area, contact pressure, and contact area. Our in vitro study used a hip joint simulator and finite element analysis to assess the effects of cup orientation at 4 angles (0°, 40°, 50°, 70°) on wear and contact properties. Polyethylene bearings with 28-mm cobalt-chrome femoral heads were cycled in an environment mimicking in vivo joint fluid to determine the volumetric wear rate after 10 million cycles. Contact pressure and contact area for each cup abduction angle were assessed using finite element analysis. Results were correlated with cup abduction angles to determine if there were any differences among the 4 groups. The inverse relationship between volumetric wear rate and acetabular cup inclination angle demonstrated less wear with steeper cup angles. The largest abduction angle (70°) had the lowest contact area, largest contact pressure, and smallest head coverage. Conversely, the smallest abduction angle (0°) had the most wear and most head coverage. Polyethylene wear after total hip arthroplasty is a major cause of osteolysis and aseptic loosening, which may lead to premature implant failure. Several studies have found that high wear rates for cups oriented at steep angles contributed to their failure. Our data demonstrated that larger cup abduction angles were associated with lower, not higher, wear. However, this potentially "protective" effect is likely counteracted by other complications of steep cup angles, including impingement, instability, and edge loading. These factors may be more relevant in explaining why implants fail at a higher rate if cups are oriented at more than 40° of abduction.

A generalized technique for using cones and dihedral angles in attitude determination, revision 1

NASA Technical Reports Server (NTRS)

Werking, R. D.

1973-01-01

Analytic development is presented for a general least squares attitude determination subroutine applicable to spinning satellites. The method is founded on a geometric approach which is completely divorced from considerations relating to particular types and configurations of onboard attitude sensors. Any mix of sensor measurements which can be first transformed (outside the program) to cone or dihedral angle data can be processed. A cone angle is an angle between the spin axis and a known direction line in space; a dihedral angle is an angle between two planes formed by the spin axis and each of two known direction lines. Many different kinds of sensor data can be transformed to these angles, which in turn constitute the actual program inputs, so that the subroutine can be applied without change to a variety of satellite missions. Either a constant or dynamic spin axis model can be handled. The program is also capable of solving for fixed biases in the input angles, in addition to the spin axis attitude solution.

A Biomechanical Investigation of A Single-Limb Squat: Implications for Lower Extremity Rehabilitation Exercise

PubMed Central

Richards, Jim; Thewlis, Dominic; Selfe, James; Cunningham, Andrew; Hayes, Colin

2008-01-01

Context: Single-limb squats on a decline angle have been suggested as a rehabilitative intervention to target the knee extensors. Investigators, however, have presented very little empirical research in which they have documented the biomechanics of these exercises or have determined the optimum angle of decline used. Objective: To determine the involvement of the gastrocnemius and rectus femoris muscles and the external ankle and knee joint moments at 60° of knee flexion while performing a single-limb squat at different decline angles. Design: Participants acted as their own controls in a repeated-measures design. Patients or Other Participants: We recruited 10 participants who had no pain, injury, or neurologic disorder. Intervention(s): Participants performed single-limb squats at different decline angles. Main Outcome Measure(s): Angle-specific knee and ankle moments were calculated at 60° of knee flexion. Angle-specific electromyography (EMG) activity was calculated at 60° of knee flexion. Integrated EMG also was calculated to determine the level of muscle activity over the entire squat. Results: An increase was seen in the knee moments (P < .05) and integrated EMG in the rectus femoris (P < .001) as the decline angle increased. A decrease was seen in the ankle moments as the decline angle increased (P  =  .001), but EMG activity in the gastrocnemius increased between 16° and 24° (P  =  .018). Conclusions: As the decline angle increased, the knee extensor moment and EMG activity increased. As the decline angle increased, the ankle plantar-flexor moments decreased; however, an increase in the EMG activity was seen with the 24° decline angle compared with the 16° decline angle. This indicates that decline squats at an angle greater than 16° may not reduce passive calf tension, as was suggested previously, and may provide no mechanical advantage for the knee. PMID:18833310

Apparent and microscopic dynamic contact angles in confined flows

NASA Astrophysics Data System (ADS)

Omori, Takeshi; Kajishima, Takeo

2017-11-01

An abundance of empirical correlations between a dynamic contact angle and a capillary number representing a translational velocity of a contact line have been provided for the last decades. The experimentally obtained dynamic contact angles are inevitably apparent contact angles but often undistinguished from microscopic contact angles formed right on the wall. As Bonn et al. ["Wetting and spreading," Rev. Mod. Phys. 81, 739-805 (2009)] pointed out, however, most of the experimental studies simply report values of angles recorded at some length scale which is quantitatively unknown. It is therefore hard to evaluate or judge the physical validity and the generality of the empirical correlations. The present study is an attempt to clear this clutter regarding the dynamic contact angle by measuring both the apparent and the microscopic dynamic contact angles from the identical data sets in a well-controlled manner, by means of numerical simulation. The numerical method was constructed so that it reproduced the fine details of the flow with a moving contact line predicted by molecular dynamics simulations [T. Qian, X. Wang, and P. Sheng, "Molecular hydrodynamics of the moving contact line in two-phase immiscible flows," Commun. Comput. Phys. 1, 1-52 (2006)]. We show that the microscopic contact angle as a function of the capillary number has the same form as Blake's molecular-kinetic model [T. Blake and J. Haynes, "Kinetics of liquid/liquid displacement," J. Colloid Interface Sci. 30, 421-423 (1969)], regardless of the way the flow is driven, the channel width, the mechanical properties of the receding fluid, and the value of the equilibrium contact angle under the conditions where the Reynolds and capillary numbers are small. We have also found that the apparent contact angle obtained by the arc-fitting of the interface behaves surprisingly universally as claimed in experimental studies in the literature [e.g., X. Li et al., "An experimental study on dynamic pore wettability," Chem. Eng. Sci. 104, 988-997 (2013)], although the angle deviates significantly from the microscopic contact angle. It leads to a practically important point that it suffices to measure arc-fitted contact angles to make formulae to predict flow rates in capillary tubes.

Flight test of the X-29A at high angle of attack: Flight dynamics and controls

NASA Technical Reports Server (NTRS)

Bauer, Jeffrey E.; Clarke, Robert; Burken, John J.

1995-01-01

The NASA Dryden Flight Research Center has flight tested two X-29A aircraft at low and high angles of attack. The high-angle-of-attack tests evaluate the feasibility of integrated X-29A technologies. More specific objectives focus on evaluating the high-angle-of-attack flying qualities, defining multiaxis controllability limits, and determining the maximum pitch-pointing capability. A pilot-selectable gain system allows examination of tradeoffs in airplane stability and maneuverability. Basic fighter maneuvers provide qualitative evaluation. Bank angle captures permit qualitative data analysis. This paper discusses the design goals and approach for high-angle-of-attack control laws and provides results from the envelope expansion and handling qualities testing at intermediate angles of attack. Comparisons of the flight test results to the predictions are made where appropriate. The pitch rate command structure of the longitudinal control system is shown to be a valid design for high-angle-of-attack control laws. Flight test results show that wing rock amplitude was overpredicted and aileron and rudder effectiveness were underpredicted. Flight tests show the X-29A airplane to be a good aircraft up to 40 deg angle of attack.

Mid-section of a can-annular gas turbine engine with an improved rotation of air flow from the compressor to the turbine

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

Little, David A.; Schilp, Reinhard; Ross, Christopher W.

A midframe portion (313) of a gas turbine engine (310) is presented and includes a compressor section with a last stage blade to orient an air flow (311) at a first angle (372). The midframe portion (313) further includes a turbine section with a first stage blade to receive the air flow (311) oriented at a second angle (374). The midframe portion (313) further includes a manifold (314) to directly couple the air flow (311) from the compressor section to a combustor head (318) upstream of the turbine section. The combustor head (318) introduces an offset angle in the airmore » flow (311) from the first angle (372) to the second angle (374) to discharge the air flow (311) from the combustor head (318) at the second angle (374). While introducing the offset angle, the combustor head (318) at least maintains or augments the first angle (372).« less

Test technology on divergence angle of laser range finder based on CCD imaging fusion

NASA Astrophysics Data System (ADS)

Shi, Sheng-bing; Chen, Zhen-xing; Lv, Yao

2016-09-01

Laser range finder has been equipped with all kinds of weapons, such as tank, ship, plane and so on, is important component of fire control system. Divergence angle is important performance and incarnation of horizontal resolving power for laser range finder, is necessary appraised test item in appraisal test. In this paper, based on high accuracy test on divergence angle of laser range finder, divergence angle test system is designed based on CCD imaging, divergence angle of laser range finder is acquired through fusion technology for different attenuation imaging, problem that CCD characteristic influences divergence angle test is solved.

Optimal reconstruction angles

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

Cook, G.O. Jr.; Knight, L.

1979-07-01

The question of optimal projection angles has recently become of interest in the field of reconstruction from projections. Here, studies are concentrated on the n x n pixel space, where literative algorithms such as ART and direct matrix techniques due to Katz are considered. The best angles are determined in a Gauss--Markov statistical sense as well as with respect to a function-theoretical error bound. The possibility of making photon intensity a function of angle is also examined. Finally, the best angles to use in an ART-like algorithm are studied. A certain set of unequally spaced angles was found to bemore » preferred in several contexts. 15 figures, 6 tables.« less

Hovering and targeting flight simulations of a dragonfly-like flapping wing-body model by the immersed boundary-lattice Boltzmann method

NASA Astrophysics Data System (ADS)

Hirohashi, Kensuke; Inamuro, Takaji

2017-08-01

Hovering and targeting flights of the dragonfly-like flapping wing-body model are numerically investigated by using the immersed boundary-lattice Boltzmann method. The governing parameters of the problem are the Reynolds number Re, the Froude number Fr, and the non-dimensional mass m. We set the parameters at Re = 200, Fr = 15 and m = 51. First, we simulate free flights of the model for various values of the phase difference angle ϕ between the forewing and the hindwing motions and for various values of the stroke angle β between the stroke plane and the horizontal plane. We find that the vertical motion of the model depends on the phase difference angle ϕ, and the horizontal motion of the model depends on the stroke angle β. Secondly, using the above results we try to simulate the hovering flight by dynamically changing the phase difference angle ϕ and the stroke angle β. The hovering flight can be successfully simulated by a simple proportional controller of the phase difference angle and the stroke angle. Finally, we simulate a targeting flight by dynamically changing the stroke angle β.

Multiple incidence angle SIR-B experiment over Argentina

NASA Technical Reports Server (NTRS)

Cimino, Jobea; Casey, Daren; Wall, Stephen; Brandani, Aldo; Domik, Gitta; Leberl, Franz

1986-01-01

The Shuttle Imaging Radar (SIR-B), the second synthetic aperture radar (SAR) to fly aboard a shuttle, was launched on October 5, 1984. One of the primary goals of the SIR-B experiment was to use multiple incidence angle radar images to distinguish different terrain types through the use of their characteristic backscatter curves. This goal was accomplished in several locations including the Chubut Province of southern Argentina. Four descending image acquisitions were collected providing a multiple incidence angle image set. The data were first used to assess stereo-radargrammetric techniques. A digital elevation model was produced using the optimum pair of multiple incidence angle images. This model was then used to determine the local incidence angle of each picture element to generate curves of relative brightness vs. incidence angle. Secondary image products were also generated using the multi-angle data. The results of this work indicate that: (1) various forest species and various structures of a single species may be discriminated using multiple incidence angle radar imagery, and (2) it is essential to consider the variation in backscatter due to a variable incidence angle when analyzing and comparing data collected at varying frequencies and polarizations.

Decline of human tactile angle discrimination in patients with mild cognitive impairment and Alzheimer's disease.

PubMed

Yang, Jiajia; Ogasa, Takashi; Ohta, Yasuyuki; Abe, Koji; Wu, Jinglong

2010-01-01

There is a need to differentiate between patients with mild cognitive impairment (MCI) and Alzheimer's disease (AD) from normal-aged controls (NC) in the field of clinical drug discovery. In this study, we developed a tactile angle discrimination system and examined whether the ability to discriminate tactile angle differed between patients with MCI and AD and the NC group. Thirty-seven subjects were divided into three groups: NC individuals (n=14); MCI patients (n=10); and probable AD patients (n=13). All subjects were asked to differentiate the relative sizes of the reference angle (60°) and one of eight comparison angles by passive touch. The accuracy of angle discrimination was measured and the discrimination threshold was calculated. We discovered that there were significant differences in the angle discrimination thresholds of AD patients compared to the NC group. Interestingly, we also found that ability to discriminate tactile angle of MCI patients were significantly lower than that of the NC group. This is the first study to report that patients with MCI and AD have substantial performance deficits in tactile angle discrimination compared to the NC individuals. This finding may provide a monitor and therapeutic approach in AD diagnosis and treatment.

Can orbital angle morphology distinguish dogs from wolves?

PubMed

Janssens, Luc; Spanoghe, Inge; Miller, Rebecca; Van Dongen, Stefan

For more than a century, the orbital angle has been studied by many authors to distinguish dog skulls from their progenitor, the wolf. In early studies, the angle was reported to be different between dogs (49°-55°) and wolves (39°-46°). This clear difference was, however, questioned in a more recent Scandinavian study that shows some overlap. It is clear that in all studies several methodological issues were unexplored or unclear and that group sizes and the variety of breeds and wolf subspecies were small. Archaeological dog skulls had also not been studied. Our goal was to test larger and more varied groups and add archaeological samples as they are an evolutionary stage between wolves and modern dogs. We also tested the influence of measuring methods, intra- and inter-reliability, angle symmetry, the influence of variations in skull position and the possibility of measuring and comparing this angle on 3D CT scan images. Our results indicate that there is about 50 % overlap between the angle range in wolves and modern dogs. However, skulls with a very narrow orbital angle were only found in wolves and those with a very wide angle only in dogs. Archaeological dogs have a mean angle very close to the one of the wolves. Symmetry is highest in wolves and lowest in archaeological dogs. The measuring method is very reliable, for both inter- and intra-reliability (0.99-0.97), and most skull position changes have no statistical influence on the angle measured. Three-dimensional CT scan images can be used to measure OA, but the angles differ from direct measuring and cannot be used for comparison. Evolutionary changes in dog skulls responsible for the wider OA compared to wolf skulls are mainly the lateralisation of the zygomatic process of the frontal bone. Our conclusion is that the orbital angle can be used as an additional morphological measuring method to discern wolves from recent and archaeological dogs. Angles above 60° are certainly from recent dogs. Angles under 35° are certainly of wolves.

[Effect of 45 degree angle semirecumbent position on ventilator-associated pneumonia in mechanical ventilated patients: a meta-analysis].

PubMed

Leng, Yu-xin; Song, Ya-han; Yao, Zhi-yuan; Zhu, Xi

2012-10-01

To systemically analyze the effect of 45 degree angle semirecumbent position on the incidence of ventilator-associated pneumonia (VAP) and other outcomes in mechanical ventilated patients, and to evaluate whether 45 degree angle semirecumbent position is superior to 25 degree angle-30 degree angle head of bed (HOB). The randomized controlled trials (RCTs) comparing the effect of different HOB on the outcomes of mechanical ventilated patients were searched (from 1st January 1990 to 20th July 2012) from five databases including the Cochrane Central Register of Controlled Trials, MEDLINE, Embase, China Knowledge Resource Integrated Database (CNKI), and Wanfang Database. Meta analysis was conducted using RevMan 5.0 software. Data extracted from five RCTs with a total of 427 patients were analyzed. The risks of developing clinically diagnosed VAP were significantly lower among the patients in semirecumbent 45 degree angle position compared to the patients in lower position [15.96% (34/213) vs. 26.64% (57/214), relative risk (RR)=0.57, 95% confidence interval (95%CI) 0.39 to 0.83, P=0.003], while no significant differences were detected between the two groups regarding the mortality rate [27.04% (53/196) vs. 28.22% (57/202), RR=0.93, 95%CI 0.68 to 1.27, P=0.66], the length of intensive care unit (ICU) stay [weighted mean difference (WMD)=-0.45, 95%CI -1.08 to 0.18, P=0.16] and the percentage of antibiotics treatment [71.11% (32/45) vs. 60.87% (28/46), RR=1.14, 95%CI 0.85 to 1.53, P=0.37]. Two of the five trials (91 patients) were included in the sub-analysis between 45 degree angle group (45 patients) and 25 degree angle-30 degree angle group (46 patients). The results showed that comparing with 25 degree angle-30 degree angle, 45 degree angle semirecumbent position had no significance in improving patients' clinical outcomes. This study proved that the clinically preferred semirecumbent 45 degree angle position did have effect in reducing the incidence of VAP, nevertheless, whether it's superior to 25 degree angle-30 degree angle needs to be confirmed by larger-scale, higher-quality RCTs.

[Determination of contact angle of pharmaceutical excipients and regulating effect of surfactants on their wettability].

PubMed

Hua, Dong-dong; Li, He-ran; Yang, Bai-xue; Song, Li-na; Liu, Tiao-tiao; Cong, Yu-tang; Li, San-ming

2015-10-01

To study the effects of surfactants on wettability of excipients, the contact angles of six types of surfactants on the surface of two common excipients and mixture of three surfactants with excipients were measured using hypsometry method. The results demonstrated that contact angle of water on the surface of excipients was associated with hydrophilcity of excipients. Contact angle was lowered with increase in hydrophilic groups of excipient molecules. The sequence of contact angle from small to large was starch < sodium benzoate < polyvinylpyrrolidone < sodium carboxymethylcellulose < sodium alginate < chitosan < hydroxypropyl methyl cellulose

Computer programs for the calculation of dual sting pitch and roll angles required for an articulated sting to obtain angles of attack and sideslip on wind-tunnel models

NASA Technical Reports Server (NTRS)

Peterson, John B., Jr.

1991-01-01

Two programs were developed to calculate the pitch and roll position of the conventional sting drive and the pitch of a high angle articulated sting to position a wind tunnel model at the desired angle of attack and sideslip and position the model as near as possible to the centerline of the tunnel. These programs account for the effects of sting offset angles, sting bending angles, and wind-tunnel stream flow angles. In addition, the second program incorporates inputs form on-board accelerometers that measure model pitch and roll with respect to gravity. The programs are presented and a description of the numerical operation of the programs with a definition of the variables used in the programs is given.

Optimization design of the angle detecting system used in the fast steering mirror

NASA Astrophysics Data System (ADS)

Ni, Ying-xue; Wu, Jia-bin; San, Xiao-gang; Gao, Shi-jie; Ding, Shao-hang; Wang, Jing; Wang, Tao; Wang, Hui-xian

2018-01-01

In this paper, in order to design a fast steering mirror (FSM) with large deflection angle and high linearity, a deflection angle detecting system (DADS) using quadrant detector (QD) is developed. And the mathematical model describing DADS is established by analyzing the principle of position detecting and error characteristics of QD. Based on this mathematical model, the variation tendencies of deflection angle and linearity of FSM are simulated. Then, by changing the parameters of the DADS, the optimization of deflection angle and linearity of FSM is demonstrated. Finally, a QD-based FSM is designed based on this method, which achieves ±2° deflection angle and 0.72% and 0.68% linearity along x and y axis, respectively. Moreover, this method will be beneficial to the design of large deflection angle and high linearity FSM.

Complete 360° circumferential gonioscopic optical coherence tomography imaging of the iridocorneal angle

PubMed Central

McNabb, Ryan P.; Challa, Pratap; Kuo, Anthony N.; Izatt, Joseph A.

2015-01-01

Clinically, gonioscopy is used to provide en face views of the ocular angle. The angle has been imaged with optical coherence tomography (OCT) through the corneoscleral limbus but is currently unable to image the angle from within the ocular anterior chamber. We developed a novel gonioscopic OCT system that images the angle circumferentially from inside the eye through a custom, radially symmetric, gonioscopic contact lens. We present, to our knowledge, the first 360° circumferential volumes (two normal subjects, two subjects with pathology) of peripheral iris and iridocorneal angle structures obtained via an internal approach not typically available in the clinic. PMID:25909021

Spectral data of specular reflectance, narrow-angle transmittance and angle-resolved surface scattering of materials for solar concentrators.

PubMed

Good, Philipp; Cooper, Thomas; Querci, Marco; Wiik, Nicolay; Ambrosetti, Gianluca; Steinfeld, Aldo

2016-03-01

The spectral specular reflectance of conventional and novel reflective materials for solar concentrators is measured with an acceptance angle of 17.5 mrad over the wavelength range 300-2500 nm at incidence angles 15-60° using a spectroscopic goniometry system. The same experimental setup is used to determine the spectral narrow-angle transmittance of semi-transparent materials for solar collector covers at incidence angles 0-60°. In addition, the angle-resolved surface scattering of reflective materials is recorded by an area-scan CCD detector over the spectral range 350-1050 nm. A comprehensive summary, discussion, and interpretation of the results are included in the associated research article "Spectral reflectance, transmittance, and angular scattering of materials for solar concentrators" in Solar Energy Materials and Solar Cells.

Spherical grating monochromator with interferometer control and in-vacuum reference

NASA Astrophysics Data System (ADS)

Holly, D. J.; Mason, W. P.; Sailor, T.; Smith, R. E.; Wahl, D.

2002-03-01

Physical Science Laboratory's new generation of spherical grating monochromators incorporates a laser interferometer to control scan angle and an in-vacuum absolute angle reference, as well as other improvements. The design accommodates up to six gratings which can be moved axially (under motor control, with encoder position readback) at any scan angle. The gratings are cooled by means of spring-loaded clamps which conduct heat to a water-cooled plate. The instruments feature hollow roller bearings on the scan axis to minimize bearing runout, and a pseudosine-bar drive for precise control of grating angle. The interferometer angle-measuring optics are mounted inside the vacuum chamber and measure the angle between the grating scan axis and the instrument's granite base. The laser interferometer measures the grating angle with a resolution of approximately 0.02 arcsec over the entire scan range of 40°. To provide a reference for the interferometer angle measurement, we have built an in-vacuum optical reference which uses custom chrome-on-glass reticles mounted inside the vacuum chamber. Collimated light from a source outside the vacuum passes through the reticles to yield quadrature signals which precisely define an absolute reference angle for the interferometer. Repeatability of the grating angle is within a range of ±0.05 arcsec. Two of these instruments are in operation at SRRC (Taiwan) and a third instrument has been delivered to NSLS (Brookhaven).

Factors influencing the effective spray cone angle of pressure-swirl atomizers

NASA Astrophysics Data System (ADS)

Chen, S. K.; Lefebvre, A. H.; Rollbuhler, J.

1992-01-01

The spray cone angles produced by several simplex pressure-swirl nozzles are examined using three liquids whose viscosities range from 0.001 to 0.012 kg/ms (1 to 12 cp). Measurements of both the visible spray cone angle and the effective spray cone angle are carried out over wide ranges of injection pressure and for five different values of the discharge orifice length/diameter ratio. The influence of the number of swirl chamber feed slots on spray cone angle is also examined. The results show that the spray cone angle widens with increase in injection pressure but is reduced by increases in liquid viscosity and/or discharge orifice length/diameter ratio. Variation in the number of swirl chamber feed slots between one and three has little effect on the effective spray cone angle.

The influence of age, sex, population group, and dentition on the mandibular angle as measured on a South African sample.

PubMed

Oettlé, Anna C; Becker, Piet J; de Villiers, Elzabe; Steyn, Maryna

2009-08-01

The mandibular angle is measured in physical anthropological assessments of human remains to possibly assist with the determination of sex and population affinity. The purpose of this investigation was to establish how the mandibular angle changes with age and loss of teeth among the sexes in South African population groups. The angles of 653 dried adult mandibles from the Pretoria Bone Collection were measured with a mandibulometer. Males and females of both South African whites and blacks were included. To compensate for imbalances in numbers among subgroups, type IV ANOVA testing was applied. No association was found between age and angle within either of the populations, within sexes, or within dentition groups. The angle was the most obtuse in individuals without molars and with an uneven distribution of molars, and most acute in the group with an even distribution of molars on both sides. Statistically significant differences (P < 0.001) were found in the angle between the two population groups and sexes in the overall sample as well as in the subgroup with absent molar teeth (P = 0.003 for sex, males more acute angle, and P = 0.001 for population group, blacks more acute angle), although a very large overlap existed. No significant differences could be demonstrated between the sexes or populations within the subgroups with molars. We concluded that the loss of molars, especially if complete or uneven, has a considerable effect on the mandibular angle. In the assessment of human remains, the mandibular angle is not very usable in determining sex.

Qualitative evaluation of the iris and ciliary body by ultrasound biomicroscopy in subjects with angle closure.

PubMed

Ku, Judy Y; Nongpiur, Monisha E; Park, Judy; Narayanaswamy, Arun K; Perera, Shamira A; Tun, Tin A; Kumar, Rajesh S; Baskaran, Mani; Aung, Tin

2014-12-01

To qualitatively analyze anterior chamber structures imaged by ultrasound biomicroscopy (UBM) in primary angle-closure patients. Subjects diagnosed as primary angle-closure suspect (PACS), primary angle-closure glaucoma (PACG), and previous acute primary angle closure (APAC) were recruited prospectively along with a group of normal controls. UBM was performed under standardized dark room conditions and qualitative assessment was carried out using a set of reference photographs of standard UBM images to categorize the various anatomic features related to angle configuration. These included overall and basal iris thicknesses, iris convexity, iris angulation, ciliary body size, and ciliary sulcus. A total of 60 PACS, 114 PACG, 41 APAC, and 33 normal controls were included. Patients were predominantly older Chinese females. After controlling the confounding effect of age and sex, eyes with overall thicker irides [medium odds ratio (OR) 3.58, thick OR 2.84] when compared with thin irides have a significantly higher likelihood of having PACS/PACG/APAC versus controls. Thicker basal iris component (medium OR 4.13, thick OR 3.39) also have higher likelihood of having angle closure when compared with thin basal iris thickness. Subjects with basal iris insertion, mild iris angulation, and large ciliary body have a higher OR of having angle closure. In contrast, the presence/absence of a ciliary sulcus did not influence the likelihood of angle closure. Eyes with thicker overall and basal iris thicknesses are more likely to have angle closure than controls. Other features that increase the likelihood of angle closure include basal iris insertion, mild iris angulation, and large ciliary body.

Novel Tiltmeter for Monitoring Angle Shift In Incident Waves

DTIC Science & Technology

2008-12-01

40th Annual Precise Time and Time Interval (PTTI) Meeting 559   NOVEL TILTMETER FOR MONITORING ANGLE SHIFT IN INCIDENT WAVES S... Tiltmeter For Monitoring Angle Shift In Incident Waves 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) 5d. PROJECT...up, any angle change of the incident beam ’θ results in a change of the intensity transmission of the resonator.     A NOVEL ANGLE TILTMETER

Measurement of Angle Kappa Using Ultrasound Biomicroscopy and Corneal Topography.

PubMed

Yeo, Joon Hyung; Moon, Nam Ju; Lee, Jeong Kyu

2017-06-01

To introduce a new convenient and accurate method to measure the angle kappa using ultrasound biomicroscopy (UBM) and corneal topography. Data from 42 eyes (13 males and 29 females) were analyzed in this study. The angle kappa was measured using Orbscan II and calculated with UBM and corneal topography. The angle kappa of the dominant eye was compared with measurements by Orbscan II. The mean patient age was 36.4 ± 13.8 years. The average angle kappa measured by Orbscan II was 3.98° ± 1.12°, while the average angle kappa calculated with UBM and corneal topography was 3.19° ± 1.15°. The difference in angle kappa measured by the two methods was statistically significant (p < 0.001). The two methods showed good reliability (intraclass correlation coefficient, 0.671; p < 0.001). Bland-Altman plots were used to demonstrate the agreement between the two methods. We designed a new method using UBM and corneal topography to calculate the angle kappa. This method is convenient to use and allows for measurement of the angle kappa without an expensive device. © 2017 The Korean Ophthalmological Society

Measurement of Angle Kappa Using Ultrasound Biomicroscopy and Corneal Topography

PubMed Central

Yeo, Joon Hyung; Moon, Nam Ju

2017-01-01

Purpose To introduce a new convenient and accurate method to measure the angle kappa using ultrasound biomicroscopy (UBM) and corneal topography. Methods Data from 42 eyes (13 males and 29 females) were analyzed in this study. The angle kappa was measured using Orbscan II and calculated with UBM and corneal topography. The angle kappa of the dominant eye was compared with measurements by Orbscan II. Results The mean patient age was 36.4 ± 13.8 years. The average angle kappa measured by Orbscan II was 3.98° ± 1.12°, while the average angle kappa calculated with UBM and corneal topography was 3.19° ± 1.15°. The difference in angle kappa measured by the two methods was statistically significant (p < 0.001). The two methods showed good reliability (intraclass correlation coefficient, 0.671; p < 0.001). Bland-Altman plots were used to demonstrate the agreement between the two methods. Conclusions We designed a new method using UBM and corneal topography to calculate the angle kappa. This method is convenient to use and allows for measurement of the angle kappa without an expensive device. PMID:28471103

A Comparison of Angular Values of the Pelvic Limb with Normal and Medial Patellar Luxation Stifles in Chihuahua Dogs Using Radiography and Computed Tomography.

PubMed

Phetkaew, Thitaporn; Kalpravidh, Marissak; Penchome, Rampaipat; Wangdee, Chalika

2018-02-01

 This article aimed to determine and compare the angular values of the pelvic limb in normal and medial patellar luxation (MPL) stifles in Chihuahuas using radiography and computed tomographic (CT) scan, to identify the relationship between pelvic limb angles and severity of MPL. In addition, radiographic and CT images were compared to determine the more suitable method of limb deformity assessment.  Sixty hindlimbs of Chihuahuas were divided into normal and grade 1, 2, 3 and 4 MPL groups. The pelvic limb angles in frontal and sagittal planes were evaluated on radiography and CT scan. Femoral and tibial torsion angles (FTA and TTA) were evaluated only by CT scan. All angles were compared among normal and MPL stifles and between radiography and CT scan.  Based on the CT scan, the mechanical lateral distal femoral angle (mLDFA), anatomical caudal proximal femoral angle (aCdPFA), and TTA were related to the severity of MPL. The mLDFA and TTA were significantly increased ( p  < 0.05) in grade 4 MPL, while the aCdPFA was significantly decreased in grade 2, 3 and 4 MPL groups. There were significant differences of many angles between radiography and CT scan.  The angles related to MPL in Chihuahuas are aLDFA, mLDFA, aCdPFA and TTA. Radiography had some limitations for evaluating pelvic limb angles. The caudocranial radiograph is recommended for the assessment of the distal femoral angles, while the craniocaudal radiograph is for the tibial angles. Schattauer GmbH Stuttgart.

Bilateral phacomorphic angle-closure glaucoma in a highly myopic patient secondary to isolated spherophakia.

PubMed

Sowka, Joseph; Girgis, Nadine

2010-09-01

Angle closure most commonly occurs in older hyperopic patients as a result of primary relative pupil block. Less frequently, angle closure occurs in highly myopic patients with conditions other than primary relative pupil block. This report presents the diagnosis, pathophysiologic mechanism, and management of a patient with both high myopia and bilateral advanced phacomorphic angle-closure glaucoma caused by isolated spherophakia. A 40-year-old asymptomatic man with very high myopic astigmatism presented with chronic angle closure and an intraocular pressure of 42 mmHg in both eyes. Additionally there was a nonmyopic fundus and 24-mm axial length, with a clear crystalline lens protruding through the pupillary plane in each eye, confirmed by B-scan ultrasonography. Gonioscopy and A-scan and B-scan ultrasonography identified the pathogenesis of intraocular pressure elevation, angle closure, and high myopia to be lenticular in origin. Initial medical therapy and subsequent laser iridotomy relieved the pupil block angle closure and successfully lowered intraocular pressure. Angle closure can occur in highly myopic eyes. Careful gonioscopy and ultrasonography can lead to the correct diagnosis and tailored management for these eyes. Phacomorphic angle-closure glaucoma from spherophakia is associated with Weill-Marchesani syndrome as well as a few other uncommon syndromes. Isolated pseudophakia is a rarely reported cause of phacomorphic angle closure. Copyright 2010 American Optometric Association. Published by Elsevier Inc. All rights reserved.

Effectiveness of Variable-Gain Kalman Filter Based on Angle Error Calculated from Acceleration Signals in Lower Limb Angle Measurement with Inertial Sensors

PubMed Central

Watanabe, Takashi

2013-01-01

The wearable sensor system developed by our group, which measured lower limb angles using Kalman-filtering-based method, was suggested to be useful in evaluation of gait function for rehabilitation support. However, it was expected to reduce variations of measurement errors. In this paper, a variable-Kalman-gain method based on angle error that was calculated from acceleration signals was proposed to improve measurement accuracy. The proposed method was tested comparing to fixed-gain Kalman filter and a variable-Kalman-gain method that was based on acceleration magnitude used in previous studies. First, in angle measurement in treadmill walking, the proposed method measured lower limb angles with the highest measurement accuracy and improved significantly foot inclination angle measurement, while it improved slightly shank and thigh inclination angles. The variable-gain method based on acceleration magnitude was not effective for our Kalman filter system. Then, in angle measurement of a rigid body model, it was shown that the proposed method had measurement accuracy similar to or higher than results seen in other studies that used markers of camera-based motion measurement system fixing on a rigid plate together with a sensor or on the sensor directly. The proposed method was found to be effective in angle measurement with inertial sensors. PMID:24282442

Preferred viewing distance and screen angle of electronic paper displays.

PubMed

Shieh, Kong-King; Lee, Der-Song

2007-09-01

This study explored the viewing distance and screen angle for electronic paper (E-Paper) displays under various light sources, ambient illuminations, and character sizes. Data analysis showed that the mean viewing distance and screen angle were 495 mm and 123.7 degrees. The mean viewing distances for Kolin Chlorestic Liquid Crystal display was 500 mm, significantly longer than Sony electronic ink display, 491 mm. Screen angle for Kolin was 127.4 degrees, significantly greater than that of Sony, 120.0 degrees. Various light sources revealed no significant effect on viewing distances; nevertheless, they showed significant effect on screen angles. The screen angle for sunlight lamp (D65) was similar to that of fluorescent lamp (TL84), but greater than that of tungsten lamp (F). Ambient illumination and E-paper type had significant effects on viewing distance and screen angle. The higher the ambient illumination was, the longer the viewing distance and the lesser the screen angle. Character size had significant effect on viewing distances: the larger the character size, the longer the viewing distance. The results of this study indicated that the viewing distance for E-Paper was similar to that of visual display terminal (VDT) at around 500 mm, but greater than normal paper at about 360 mm. The mean screen angle was around 123.7 degrees, which in terms of viewing angle is 29.5 degrees below horizontal eye level. This result is similar to the general suggested viewing angle between 20 degrees and 50 degrees below the horizontal line of sight.

Riding position and lumbar spine angle in recreational cyclists: A pilot study

PubMed Central

SCHULZ, SAMANTHA J.; GORDON, SUSAN J.

2010-01-01

This pilot study investigated the reliability of an inclinometer to assess lumbar spine angle in three different cycling positions, and explored the relationship between lumbar spine angle and riding position, anthropometry, bike measures and low back pain (LBP). Cyclists were recruited from two cycle clubs. Anthropometric variables and bike setup were measured before participants’ bikes were secured in a wind trainer. Cyclists then adopted three positions for riding, upright on the handlebars, on the brake levers and on the drops, according to a random allocation. The angle of the lumbar spine was measured; using an inclinometer, at zero minutes and after cyclists had completed 10 minutes of cycling. Intra-measurer reliability for inclinometer use to measure lumbar spine angle in each position was excellent (ICC=0.97). The angle of the lumbar spine changed significantly over 10 minutes in the brake position (p=0.004). Lumbar spine angle at 10 minutes was significantly different between the brake and drop positions (p=0.018, p<0.05), and between upright and drop positions (p=0.012, p<0.05). Lumbar spine angle was not related to anthropometric measures. The change in lumbar spine angle varied from one degree of extension to 12 degrees of flexion, with increased flexion occurring in 95% of trials. An inclinometer has excellent intra-measurer reliability to measure lumbar spine angle in cycling positions. Future research with a sample of 72 or more participants is required to determine if there is a significant relationship between LBP and lumbar spine angle in different cycling positions. PMID:27182345

Fostering Students' Development of the Concept of Angles Using Technology

ERIC Educational Resources Information Center

Richardson, Sue Ellen; Koyunkaya, Melike Yigit

2017-01-01

We have used "GeoGebra," a dynamic geometry software environment, to explore how Year 4 students understand definitions of angles. Seven students defined angle and then completed several activities adapted for the dynamic environment. Afterward, students again shared their definitions of angles. We found that even a short investigation…

47 CFR 25.205 - Minimum angle of antenna elevation.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 47 Telecommunication 2 2012-10-01 2012-10-01 false Minimum angle of antenna elevation. 25.205... SATELLITE COMMUNICATIONS Technical Standards § 25.205 Minimum angle of antenna elevation. (a) Earth station antennas shall not normally be authorized for transmission at angles less than 5° measured from the...

47 CFR 25.205 - Minimum angle of antenna elevation.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 47 Telecommunication 2 2011-10-01 2011-10-01 false Minimum angle of antenna elevation. 25.205... SATELLITE COMMUNICATIONS Technical Standards § 25.205 Minimum angle of antenna elevation. (a) Earth station antennas shall not normally be authorized for transmission at angles less than 5° measured from the...

47 CFR 25.205 - Minimum angle of antenna elevation.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 47 Telecommunication 2 2014-10-01 2014-10-01 false Minimum angle of antenna elevation. 25.205... SATELLITE COMMUNICATIONS Technical Standards § 25.205 Minimum angle of antenna elevation. (a) Earth station antennas shall not normally be authorized for transmission at angles less than 5° measured from the...

47 CFR 25.205 - Minimum angle of antenna elevation.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 47 Telecommunication 2 2013-10-01 2013-10-01 false Minimum angle of antenna elevation. 25.205... SATELLITE COMMUNICATIONS Technical Standards § 25.205 Minimum angle of antenna elevation. (a) Earth station antennas shall not normally be authorized for transmission at angles less than 5° measured from the...

89. 22'X34' original vellum, VariableAngle Launcher 'ELEVATION OF LAUNCHER BRIDGE ...

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

89. 22'X34' original vellum, Variable-Angle Launcher 'ELEVATION OF LAUNCHER BRIDGE ON TEMPORARY SUPPORT' drawn at 1'=20'. (BUORD Sketch # 209786, PAPW 1932). - Variable Angle Launcher Complex, Variable Angle Launcher, CA State Highway 39 at Morris Reservior, Azusa, Los Angeles County, CA

90. 22'X34' original blueprint, VariableAngle Launcher, 'FRONT ELEVATION OF LAUNCHER ...

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

90. 22'X34' original blueprint, Variable-Angle Launcher, 'FRONT ELEVATION OF LAUNCHER BRIDGE, CONNECTING BRIDGE AND BARGES' drawn at 1/4'=1'0'. (BUROD Sketch # 208247). - Variable Angle Launcher Complex, Variable Angle Launcher, CA State Highway 39 at Morris Reservior, Azusa, Los Angeles County, CA

14 CFR 25.1387 - Position light system dihedral angles.

Code of Federal Regulations, 2010 CFR

2010-01-01

... this section. (b) Dihedral angle L (left) is formed by two intersecting vertical planes, the first... two intersecting vertical planes, the first parallel to the longitudinal axis of the airplane, and the... axis. (d) Dihedral angle A (aft) is formed by two intersecting vertical planes making angles of 70...

14 CFR 27.1387 - Position light system dihedral angles.

Code of Federal Regulations, 2010 CFR

2010-01-01

... this section. (b) Dihedral angle L (left) is formed by two intersecting vertical planes, the first... two intersecting vertical planes, the first parallel to the longitudinal axis of the rotorcraft, and... longitudinal axis. (d) Dihedral angle A (aft) is formed by two intersecting vertical planes making angles of 70...

Comparison of factors associated with occludable angle between american Caucasians and ethnic Chinese.

PubMed

Wang, Ye Elaine; Li, Yingjie; Wang, Dandan; He, Mingguang; Lin, Shan

2013-11-21

To determine if factors associated with gonioscopy-determined occludable angle among American Caucasians are similar to those found in ethnic Chinese. This is a prospective cross-sectional study with 120 American Caucasian, 116 American Chinese, and 116 mainland Chinese subjects. All three groups were matched for sex and age (40-80 years). Gonioscopy was performed for each subject (occludable angles = posterior trabecular meshwork not visible for ≥2 quadrants). Anterior segment optical coherence tomography and customized software was used to measure anterior segment biometry and iris parameters, including anterior chamber depth/width (ACD, ACW), lens vault (LV), and iris thickness/area/curvature. In both Chinese and Caucasians, eyes with occludable angles had smaller ACD and ACW, and larger LV and iris curvature than eyes with open angles (all P < 0.005). Chinese eyes had smaller ACD and ACW than Caucasian eyes (both P < 0.01) in the occludable angle cohort. Iris characteristics did not differ significantly between Chinese and Caucasians in the occludable angle cohort. Based on multivariate logistic regression, gonioscopy-determined occludable angle was significantly associated with LV, iris area, and sex (all P < 0.03) in Chinese; and with LV, ACD, iris thickness, age, and sex (all P < 0.04) in Caucasians. Several factors associated with occludable angle differed between Caucasians and Chinese, suggesting potentially different mechanisms in occludable angle development in the two racial groups. This is the first study to demonstrate that lens vault is an important anterior segment optical coherence tomography parameter in the screening for angle closure in Caucasians. In addition, iris thickness was a significant predictor for occludable angles in Caucasians but was not in ethnic Chinese.

Comparison of Factors Associated With Occludable Angle Between American Caucasians and Ethnic Chinese

PubMed Central

Wang, Ye Elaine; Li, Yingjie; Wang, Dandan; He, Mingguang; Lin, Shan

2013-01-01

Purpose. To determine if factors associated with gonioscopy-determined occludable angle among American Caucasians are similar to those found in ethnic Chinese. Methods. This is a prospective cross-sectional study with 120 American Caucasian, 116 American Chinese, and 116 mainland Chinese subjects. All three groups were matched for sex and age (40–80 years). Gonioscopy was performed for each subject (occludable angles = posterior trabecular meshwork not visible for ≥2 quadrants). Anterior segment optical coherence tomography and customized software was used to measure anterior segment biometry and iris parameters, including anterior chamber depth/width (ACD, ACW), lens vault (LV), and iris thickness/area/curvature. Results. In both Chinese and Caucasians, eyes with occludable angles had smaller ACD and ACW, and larger LV and iris curvature than eyes with open angles (all P < 0.005). Chinese eyes had smaller ACD and ACW than Caucasian eyes (both P < 0.01) in the occludable angle cohort. Iris characteristics did not differ significantly between Chinese and Caucasians in the occludable angle cohort. Based on multivariate logistic regression, gonioscopy-determined occludable angle was significantly associated with LV, iris area, and sex (all P < 0.03) in Chinese; and with LV, ACD, iris thickness, age, and sex (all P < 0.04) in Caucasians. Conclusions. Several factors associated with occludable angle differed between Caucasians and Chinese, suggesting potentially different mechanisms in occludable angle development in the two racial groups. This is the first study to demonstrate that lens vault is an important anterior segment optical coherence tomography parameter in the screening for angle closure in Caucasians. In addition, iris thickness was a significant predictor for occludable angles in Caucasians but was not in ethnic Chinese. PMID:24168992

Thumb rule of visual angle: a new confirmation.

PubMed

Groot, C; Ortega, F; Beltran, F S

1994-02-01

The classical thumb rule of visual angle was reexamined. Hence, the visual angle was measured as a function of a thumb's width and the distance between eye and thumb. The measurement of a thumb's width when held at arm's length was taken on 67 second-year students of psychology. The visual angle was about 2 degrees as R. P. O'Shea confirmed in 1991. Also, we confirmed a linear relationship between the size of a thumb's width at arm's length and the visual angle.

Iridotomy to slow progression of angle-closure glaucoma

PubMed Central

Le, Jimmy T; Rouse, Benjamin; Gazzard, Gus

2016-01-01

This is the protocol for a review and there is no abstract. The objectives are as follows: The primary objective is to assess the role of iridotomy-compared with observation-in the prevention of visual field loss for individuals who have primary angle closure or primary angle-closure glaucoma in at least one eye. We will also examine the role of iridotomy in the prevention of elevated intraocular pressure (IOP) in individuals with narrow angles (primary angle-closure suspect) in at least one eye. PMID:27551238