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1

Hydrophobic effects on partial molar volume  

NASA Astrophysics Data System (ADS)

The hydrophobic effects on partial molar volume (PMV) are investigated as a PMV change in the transfer of a benzenelike nonpolar solute from the nonpolar solvent to water, using an integral equation theory of liquids. The volume change is divided into two effects. One is the ``packing'' effect in the transfer from the nonpolar solvent to hypothetical ``nonpolar water'' without hydrogen bonding networks. The other is the ``iceberg'' effect in the transfer from nonpolar water to water. The results indicate that the packing effect is negative and a half compensated by the positive iceberg effect. The packing effect is explained by the difference in the solvent compressibility. Further investigation shows that the sign and magnitude of the volume change depend on the solute size and the solvent compressibility. The finding gives a significant implication that the exposure of a hydrophobic residue caused by protein denaturation can either increase or decrease the PMV of protein depending on the size of the residue and the fluctuation of its surroundings.

Imai, Takashi; Hirata, Fumio

2005-03-01

2

Partial Molar Volumes for Lanthanide Sesquioxides in Sodium Silicate Melts  

NASA Astrophysics Data System (ADS)

Lanthanides are of great interest in igneous petrology as trace indicators of magmatic processes that control the origin and evolution of igneous rocks. A key to the petrogenetic modelling of magmatic processes and to determine the phase diagrams of lanthanide host phases is the accurate determination of the physico-chemical and thermodynamic properties of lanthanide-containing materials, such as the volumetric properties of lanthanide-bearing silicate melts. Therefore, we have undertaken to provide a new reliable volumetric data set for lanthanide-bearing silicate melts which allows the available models in the literature to be extended to lanthanide-bearing melts. For this purpose, the densities of various lanthanide-bearing silicate melts distributed along various pseudo-binary joins, where the end-members are Na-disilicate and one of the lanthanide sesquioxides (i.e., Ce2O3, Pr2O3, Nd2O3, Sm2O3, Eu2O3, Gd2O3, Tb2O3, Dy2O3, Ho2O3, Er2O3, Tm2O3 and Yb2O3), have been measured using the double-bob Archimedean method. The present results show that the addition of any lanthanide to Na-disilicate leads to an increase in the melt density and that the melt density increases with increasing atomic number of the lanthanide. From the present density data set, the molar volumes of these melts have been calculated and the partial molar volumes of each lanthanide sesquioxide in these melts have been determined using a linear regression through each pseudo-binary join (i.e., Na-disilicate - lanthanide sesquioxide). This study indicates ideal behaviour with respect to the molar volume (i.e., a linear variation of the molar volume along each pseudo-binary join) for Na-silicate melts containing up to 10 mol% of lanthanide oxide. Comparison between the partial molar volumes of lanthanide sesquioxides obtained in this study and the molar volumes of molten lanthanide sesquioxides given in the literature raise the possibility however that this ideality is not maintained along the entire Na-disilicate - lanthanide sesquioxide pseudo-binary joins. Excess volumes of mixing appear to be required to describe the combined volumetric data set.

Courtial, P.; Dingwell, D. B.

2004-12-01

3

Binding constants and partial molar volumes of primary alcohols in sodium dodecylsulfate micelles  

SciTech Connect

The densities of methanol, ethanol, 1-propanol, 1-butanol and 1-hexanol were measured in aqueous solutions of sodium dodecylsulfate at 25/sup 0/C. The partial molar volumes of the alcohols at infinite dilution in the aqueous surfactants solutions were calculated and discussed using a mass-action model for the alcohol distribution between the aqueous and the micellar phase. The partial molar volumes of the alcohols in the aqueous and in the micellar phases, and the ratios between the binding constant and the aggregation number, were calculated. The partial molar volume for all the alcohols in micellar phase is 10 cm/sup 3/-mol/sup -1/ smaller than that in octane. This can be related to the strong hydrophilic interaction between the head groups of the alcohol and the micellized surfactant. From the extrapolated values of the distribution constant and the partial molar volumes in the aqueous and micellar phases, the standard partial molar volume of heptanol in micellar solutions was found to decrease with increasing surfactant concentration. The standard free energy of transfer of alcohols from water to micelles was rationalized in terms of hydrophilic and hydrophobic contributions. A model is proposed in which the empty space around each solute is assumed to be the same in the gas and liquid phases, and is used to explain the behavior of micelles in the presence of amphiphilic solutes.

DeLisi, R.; Lizzio, A.; Milioto, S.; Liveri, V.T.

1986-08-01

4

Compositional dependent partial molar volume and compressibility of CO2 in rhyolite, phonolite and basalt glasses  

NASA Astrophysics Data System (ADS)

Carbon dioxide is the second most abundant volatile in magmatic systems and plays an important role in many magmatic processes, e.g. partial melting, volatile saturation, outgassing. Despite this relevance, the volumetric properties of carbon-bearing silicates at relevant pressure and temperature conditions remain largely unknown because of considerable experimental difficulties associated with in situ measurements. Density and elasticity measurements on quenched glasses can provide an alternative source of information. For dissolved water, such measurements indicate that the partial molar volume is independent of compositions at ambient pressure [1], but the partial molar compressibility is not [2, 3]. Thus the partial molar volume of water may depend on melt composition at elevated pressure. For dissolved CO2, no such data is available. In order to constrain the effect of magma composition on the partial molar volume and compressibility of dissolved carbon, we determined the density and elasticity for three series of carbon-bearing basalt, phonolite and rhyolite glasses, quenched from 3.5 GPa and relaxed at ambient pressure. The CO2 content varies between 0 to 3.90 wt% depending on the glass composition. Glass densities were determined using the sink/float method in a diiodomethane (CH2I2) - acetone mixture. Brillouin measurements were conducted on relaxed and unrelaxed silicate glasses in platelet geometry to determine the compressional (VP) and shear (VS) wave velocities and elastic moduli. The partial molar volume of CO2 in rhyolite, phonolite and basalt glasses is 25.4 ± 0.9, 22.1 ± 0.6 and 26.6 ±1.8 cm3/mol, respectively. Thus, unlike for dissolved water, the partial molar volume of CO2 displays a resolvable compositional effect. Although the composition and CO2/carbonate speciation of the phonolite glasses is intermediate between that of the rhyolite and basalt glasses, the molar volume is not. Similar to dissolved water, the partial molar bulk modulus of CO2 displays a strong compositional effect. If these compositional dependencies persist in the analogue melts, the partial molar volume of dissolved CO2 will depend on melt composition, both at low and elevated pressure. Thus, for CO2-bearing melts, a full quantitative understanding of density dependent magmatic processes, such as crystal fractionation, magma mixing and melt extraction will require in situ measurements for a range of melt compositions. [1] Richet, P. et al., 2000, Contrib Mineral Petrol, 138, 337-347. [2] Malfait et al. 2011, Am. Mineral. 96, 1402-1409. [3] Whittington et al., 2012, Am. Mineral. 97, 455-467.

Lerch, P.; Seifert, R.; Malfait, W. J.; Sanchez-Valle, C.

2012-12-01

5

Pseudo-critical behavior on the partial molar volume of solutes in the isotropic phase of liquid crystal  

NASA Astrophysics Data System (ADS)

Temperature dependence of partial molar volume of 4-amino-4'-nitrobiphenyl (ANB) and 4,4'-dinitrobiphenyl (DNB) in the isotropic phase of 4- n-pentyl-4'-cyanobiphenyl (5CB) was determined. Addition of ANB to 5CB causes increase of isotropic-nematic phase transition temperature ( TIN) [1]. The decrease of partial molar volume of ANB was observed while the increase of partial molar volume of DNB and triphenyl phosphite (TPP) [8] was observed with approaching TIN. The anomalous behavior of partial molar volume was discussed using treatments similar to that of other thermodynamic derivatives in the I-N transition.

Matsuoka, Tatsuro; Nakamura, Shunsuke; Yamaguchi, Tsuyoshi; Koda, Shinobu

2012-01-01

6

Determination Of Partial Molar Volumes Of Iron Species In Silicate Melts  

NASA Astrophysics Data System (ADS)

One of the major questions of planetary geology is the composition and conditions of the Earth interior. Magmas are among our most important windows into the interior. Iron, being a major element with multiple valence states, is an important influence on redox state. One way to investigate redox state is via a volume equation of state. Density data are used in computing partial molar volumes, which may then be used to construct a volume equation of state. We have devised an apparatus which permits high-quality density measurements in silicate melts at high temperatures (up to ?1500 °C) and reduced oxygen fugacity at atmospheric pressure using the Archimedean single-bob method. With this apparatus, we have collected the first high-quality density data of iron-bearing silicate melts which had their iron predominately as ferrous. We measured the density of Columbia River Basalt (approximate temperature range: 1250 °C -- 1450 °C) and an artificial composition in the FeO-FeO1.5-CaO-SiO2 system (?1460 °C) at the oxygen fugacity corresponding to the Iron-Wüstite buffer. We used these data in conjunction with literature density data gathered at thermodynamic equilibrium to calculate the partial molar volume of the iron species as a function of temperature at standard pressure. We speciated iron according to: 0.4 FeO + 0.6 FeO1.5 ? FeO1.3 The partial molar volumes of FeO, FeO1.5, and FeO1.3 were fit well with no compositional dependence, despite the wide range of compositions included in this study. To the extent that melt structure can be inferred from partial molar volumes, this result suggests that there is no compositional dependency to the structure of any of these iron species. Our partial molar volumes of FeO and FeO1.5 are consistent within one standard error of those found by Lange & Carmichael (1987) and Ghiorso & Kress (2004). However, our partial molar volume for FeO1.3 at reference temperature was one-third that of Ghiorso & Kress (2004) (Lange & Carmichael (1987) did not include this species in their fit), which would result in greater conversion of FeO and FeO1.5 into FeO1.3 at pressure.

Dwyer, C. A.; Kress, V. C.

2009-12-01

7

A partial molar volume for ZnO in silicate melts.  

NASA Astrophysics Data System (ADS)

Trace elements in igneous petrology have, in comparison with major elements, a relevance in the petrogenetic modelling of magmatic differentiation that far outweighs their relative abundance. Optimal use of the information contained in trace element variations within igneous phases requires an accurate description of their partitioning behaviour as a function of phase composition and structure, as well as temperature and pressure. In this manner, the partial molar thermodynamic properties of trace elements in silicate melts may contribute to the petrogenetic modelling of such systems. With this in mind, a series of investigations into the partial molar properties of trace elements in silicate melts have been carried out in recent years. Here we extend this work to the analysis of the volumetric properties of ZnO in silicate melts. Densities of 8 Zn-bearing silicate melts have been determined in air in the temperature range of 1363 to 1850 K. The compositional joins investigated (sodium disilicate (NS2) - ZnO; anorthite-diopside 1 bar eutectic (AnDi) - ZnO; and diopside - petedunnite) were chosen based on the pre-existing experimental density data set, their petrological relevance and to provide a test for significant compositionally induced variations in the structural role of ZnO. The ZnO concentrations investigated range up to 25 mol% for sodium disilicate, 20 mol% for the anorthite-diopside 1 atm eutectic and 100 mol% petedunnite. Molar volumes and expansivities of all melts have been derived. The molar volumes of the present liquids all decrease with increasing ZnO content. The partial molar volume of ZnO derived here from the volumetric measurements for each binary system is the same within error. A multicomponent fit to the volumetric data for all compositions yields a value of 14.141(0.730) cm3.mol-1 at 1300 K. We find, herewith, no volumetric evidence for compositionally-induced coordination number variations for ZnO in alkali-bearing versus alkali-free silicate melts.

Ledda, B.; Potuzak, M.; Dingwell, D. B.; Courtial, P.

2004-12-01

8

Quadrupole terms in the Maxwell equations: Born energy, partial molar volume, and entropy of ions.  

PubMed

A new equation of state relating the macroscopic quadrupole moment density Q to the gradient of the field ?E in an isotropic fluid is derived: Q = ?Q(?E - U?·E/3), where the quadrupolarizability ?Q is proportional to the squared molecular quadrupole moment. Using this equation of state, a generalized expression for the Born energy of an ion dissolved in quadrupolar solvent is obtained. It turns out that the potential and the energy of a point charge in a quadrupolar medium are finite. From the obtained Born energy, the partial molar volume and the partial molar entropy of a dissolved ion follow. Both are compared to experimental data for a large number of simple ions in aqueous solutions. From the comparison the value of the quadrupolar length LQ is determined, LQ = (?Q/3?)(1/2) = 1-4 Å. Data for ion transfer from aqueous to polar oil solution are analyzed, which allowed for the determination of the quadrupolarizability of nitrobenzene. PMID:24559353

Slavchov, Radomir I; Ivanov, Tzanko I

2014-02-21

9

Quadrupole terms in the Maxwell equations: Born energy, partial molar volume, and entropy of ions  

NASA Astrophysics Data System (ADS)

A new equation of state relating the macroscopic quadrupole moment density seriesshape Q to the gradient of the field ?E in an isotropic fluid is derived: seriesshape Q = ?Q(?E - series U?·E/3), where the quadrupolarizability ?Q is proportional to the squared molecular quadrupole moment. Using this equation of state, a generalized expression for the Born energy of an ion dissolved in quadrupolar solvent is obtained. It turns out that the potential and the energy of a point charge in a quadrupolar medium are finite. From the obtained Born energy, the partial molar volume and the partial molar entropy of a dissolved ion follow. Both are compared to experimental data for a large number of simple ions in aqueous solutions. From the comparison the value of the quadrupolar length LQ is determined, LQ = (?Q/3?)1/2 = 1-4 Å. Data for ion transfer from aqueous to polar oil solution are analyzed, which allowed for the determination of the quadrupolarizability of nitrobenzene.

Slavchov, Radomir I.; Ivanov, Tzanko I.

2014-02-01

10

Dependences of molar volumes in solids, partial molal and hydrated ionic volumes of alkali halides on covalent and ionic radii and the golden ratio  

Microsoft Academic Search

New linear dependences are presented here for the volumes of alkali halides in crystals and in aqueous solutions: (1) the molar volumes in solids (VBo) and the partial molal volumes (?Vo) in aqueous solutions on the sums of crystal ionic volumes, V(M+,X?)cr, (2) ?Vo on VBo, (3) ?Vo on the sum of aqueous ionic volumes, V(M+,X?)aq and (4) ?Vo, VBo,

Raji Heyrovska

2007-01-01

11

Correlation and prediction of infinite-dilution partial molar volumes of organic solutes in SC CO 2 using the Peng-Robinson and PHCT equations of state and the LCVM EOS\\/G E model  

Microsoft Academic Search

An extensive infinite-dilution partial molar volume (PMV) data base of various liquid and solid solutes in supercritical carbon dioxide, including the very recent experimental partial molar volume data reported by Spicka et al. [B. Spicka, A. Cortesi, M. Fermeglia, I. Kikic, Determination of partial molar volumes at infinite dilution using SFC technique, J. Supercrit Fluids 7 (1994) 171] and Cortesi

Ph Coutsikos; K Magoulas; D Tassios; A Cortesi; I Kikic

1997-01-01

12

Partial Molar Volumes of Components and Species in O-S-Fe-Ni Oxide and Sulfide Liquids  

NASA Astrophysics Data System (ADS)

High-quality thermochemical models are now available for sulfide liquids at one bar pressure. An accurate description of the volume mixing properties of these liquids is required in order to apply these one-bar models to important problems at elevated pressure, including sulfide-hosted ore formation, sulfur cycling in convergent margin settings and core formation. Our experimental data have been combined with select density data from other laboratories to calibrate a comprehensive model for density and partial molar volumes of liquids in the O-S- Fe-Ni system. Our results indicate significant negative deviation from linear mixing across the Fe-S, Ni-S and Cu-S binaries. This result is in qualitative agreement with those from prior studies. In the context of associated homogeneous speciation models for sulfide liquids (Kress, 2000, 2007), this negative volume of mixing can be interpreted as a strongly negative volume of reaction for the formation for intermediate melt species from end member elemental components (? Vf). Our regression yields ? Vf values of -6.2, -9.4 and -9.1 cc/mol for FeS, NiS and CuS respectively. There is insufficient oxygen in experimental liquids to resolve a composition dependence for v¯O, but the unrealistic negative regressed value for oxygen partial molar volume suggests a negative ? Vf for FeO and FeO1.5. Partial molar volumes of Fe, Ni and Cu liquid species are calculated from Nash and Steinemann (1995). All other v¯i are assumed to be linear mixtures of component species volumes. This assumption also implies a moderate negative ? Vf for the species in question. The resulting model reproduces experimental densities from our laboratory with a 3.6% average error. This is comparable to the estimated measurement error. The larger 5.1% error for the full data set can be attributed to lower precision in some of the other studies and the effects of inter-laboratory error. The sulfide volume model can be applied to calculate thermochemical properties of sulfide liquids to moderate pressures. This model is used in conjunction with literature experiments on coexisting sulfide and silicate liquids at pressure to explore complex interactions between the pressure dependences of oxygen fugacity, sulfur fugacity and sulfide saturation.

Kress, V. C.

2007-12-01

13

Solubility and partial molar volumes of naphthalene, phenanthrene, benzoic acid, and 2-methoxynaphthalene in supercritical carbon dioxide  

SciTech Connect

The effect of temperature, pressure, and supercritical fluid density on the retention and solubility in the mobile phase of solutes in supercritical fluid chromatography was investigated. New retention data for naphthalene, phenanthrene, benzoic acid, and 2-methoxynaphthalene were obtained as a function of pressure at different temperatures. Most of the data were taken near the critical region of the fluid phase where the anomalities such as enhanced solubility/selectivity and retrogate behavior are expected. These data were then used to compare two different approaches for modeling the pressure dependence of solute retention on the column. In these approaches, mobile-phase partial molar volumes of the solutes were determined either from bulk solubility data or from infinite-dilution fugacity coefficients. In both approaches, an integrated expression for the change of retention with pressure was utilized to explicitly reveal the nature of interactions between the stationary phase and the solute. The approach that utilizes the infinite-dilution fugacity coefficient predicts the pressure dependence of solute retention more accurately, especially for solutes that are substantially soluble in the mobile phase near the critical point of the mobile phase. Relationships between the pressure and temperature dependence of the solute solubility in the mobile phase and the retention of solutes on the column were also investigated.

Goenenc, Z.S.; Akman, U. [Univ. of South Florida, Tampa, FL (United States). Dept. of Chemical Engineering]|[Bogaziici Univ., Istanbul (Turkey). Dept. of Chemical Engineering; Sunol, A.K. [Univ. of South Florida, Tampa, FL (United States). Dept. of Chemical Engineering

1995-07-01

14

Partial Molar Volumes and Viscosity B-Coefficients of Nicotinamide in Aqueous Resorcinol Solutions at T = (298.15, 308.15, and 318.15) K  

NASA Astrophysics Data System (ADS)

Partial molar volumes {( {? _v^o} )} and viscosity B-coefficients for nicotinamide in (0.00, 0.05, 0.10, 0.15, and 0.20) mol·dm-3 aqueous resorcinol solutions have been determined from solution density and viscosity measurements at (298.15, 308.15, and 318.15) K as a function of the concentration of nicotinamide (NA). Here the relation {? v^o =a_0 +a1 T+a2 T2}, has been used to describe the temperature dependence of the partial molar volume {? _v^o }. These results and the results obtained in pure water were used to calculate the standard volumes of transfer {? ? v^o } and viscosity B-coefficients of transfer of nicotinamide from water to aqueous resorcinol solutions to study various interactions in the ternary solutions. The partial molar volume {( {? v^o})} and experimental slopes obtained from the Masson equation have been interpreted in terms of solute-solvent and solute-solute interactions, respectively. The viscosity data have been analyzed using the Jones-Dole equation, and the derived parameters B and A have also been interpreted in terms of solute-solvent and solute-solute interactions, respectively, in the ternary solutions.The structure making or breaking ability of nicotinamide has been discussed in terms of the sign of {( {? 2? _v^o /? T2})_P}. The activation parameters of viscous flow for the ternary solutions studied were also calculated and explained by the application of transition state theory.

Roy, Mahendra Nath; Banerjee, Ashis; Roy, Pran Kumar

2009-04-01

15

New Measurements of the Densities of Copper- and Nickel-Sulfide Liquids and Preliminary Estimates of the Partial Molar Volumes of Cu, Ni, S and O  

NASA Astrophysics Data System (ADS)

We present the results of density measurements in Ni- and Cu-sulfide liquids. Density measurements were performed in-situ at 1250° C under controlled-atmosphere conditions using the modified single-bob (MSB) Archimedean method. The MSB consists of a ~2 mm diameter rod with a ~6 mm long ~7 mm diameter cylindrical bob attached ~7 mm from the base of the rod. The bob and crucible were constructed from Yt stabilized zirconia to minimize reaction with the corrosive sulfide liquid. Zirconia density at temperature was calibrated against the known density of molten Cu metal (Drotning 1981, High Temp-High Press 13: 441-458). Density was determined by measuring buoyancy as a function of immersed volume. Buoyancy was measured with a 0.1 mg resolution analytical balance interfaced with a computer. The crucible is mounted on a micrometer "elevator" allowing regulation of immersion with .005 mm resolution. Temperature was measured with an S-type thermocouple in contact with the bottom of the crucible. We explored log(fO2) from -8.2 to -12.6 and log(fS2) from -1.9 to -3.3. Five measurements have been made so far. Cu-sulfide densities range from 6.32 to 6.36 g/cc and were reproducible to +/-0.7%. Measured Ni-sulfide densities were lower, ranging from 5.27 to 5.79 g/cc. Wetting problems in Ni-sulfide compositions made these measurements more difficult. Reproducibility in Ni-sulfide melts was roughly +/-5%. Measured density values were used to regress preliminary partial molar volumes of sulfide liquids in the Cu-Ni-S-O system. A linear least squares fit was derived from the five density measurements along with the densities of pure molten Cu (Drotning 1981, ibid.) and Ni (Nasch 1995, Phys Chem Liq 29: 43-58) at 1250° C. Melt compositions under experimental conditions were estimated using the thermodynamic model of Kress (submitted). The molar volume of the system (V) can be expressed as: V = 8.18 XCu + 7.38 XNi + 30.33 XS where XI is the mole fraction of component i. Oxygen contents were too low to estimate the partial molar volume of this component.

Kress, V. C.; Ghiorso, M. S.

2001-12-01

16

Influence of hydrostatic pressure on dynamics and spatial distribution of protein partial molar volume: time-resolved surficial Kirkwood-Buff approach.  

PubMed

The influence of hydrostatic pressure on the partial molar volume (PMV) of the protein apomyoglobin (AMb) was investigated by all-atom molecular dynamics (MD) simulations. Using the time-resolved Kirkwood-Buff (KB) approach, the dynamic behavior of the PMV was identified. The simulated time average value of the PMV and its reduction by 3000 bar pressurization correlated with experimental data. In addition, with the aid of the surficial KB integral method, we obtained the spatial distributions of the components of PMV to elucidate the detailed mechanism of the PMV reduction. New R-dependent PMV profiles identified the regions that increase or decrease the PMV under the high pressure condition. The results indicate that besides the hydration in the vicinity of the protein surface, the outer space of the first hydration layer also significantly influences the total PMV change. These results provide a direct and detailed picture of pressure induced PMV reduction. PMID:20822124

Yu, Isseki; Tasaki, Tomohiro; Nakada, Kyoko; Nagaoka, Masataka

2010-09-30

17

Variation and decomposition of the partial molar volume of small gas molecules in different organic solvents derived from molecular dynamics simulations  

NASA Astrophysics Data System (ADS)

The partial molar volumes, bar V_i, of the gas solutes H2, CO, and CO2, solvated in acetone, methanol, heptane, and diethylether are determined computationally in the limit of infinite dilution and standard conditions. Solutions are described with molecular dynamics simulations in combination with the OPLS-aa force field for solvents and customized force field for solutes. bar V_i is determined with the direct method, while the composition of bar V_i is studied with Kirkwood-Buff integrals (KBIs). Subsequently, the amount of unoccupied space and size of pre-formed cavities in pure solvents is determined. Additionally, the shape of individual solvent cages is analyzed. Calculated bar V_i deviate only 3.4 cm3 mol-1 (7.1%) from experimental literature values. Experimental bar V_i variations across solutions are reproduced qualitatively and also quantitatively in most cases. The KBI analysis identifies differences in solute induced solvent reorganization in the immediate vicinity of H2 (<0.7 nm) and solvent reorganization up to the third solvation shell of CO and CO2 (<1.6 nm) as the origin of bar V_i variations. In all solutions, larger bar V_i are found in solvents that exhibit weak internal interactions, low cohesive energy density and large compressibility. Weak internal interactions facilitate solvent displacement by thermal solute movement, which enhances the size of solvent cages and thus bar V_i. Additionally, attractive electrostatic interactions of CO2 and the solvents, which do not depend on internal solvent interactions only, partially reversed the bar V_i trends observed in H2 and CO solutions where electrostatic interactions with the solvents are absent. More empty space and larger pre-formed cavities are found in solvents with weak internal interactions, however, no evidence is found that solutes in any considered solvent are accommodated in pre-formed cavities. Individual solvent cages are found to be elongated in the negative direction of solute movement. This wake behind the moving solute is more pronounced in case of mobile H2 and in solvents with weaker internal interactions. However, deviations from a spherical solvent cage shape do not influence solute-solvent radial distribution functions after averaging over all solvent cage orientations and hence do not change bar V_i. Overall, the applied methodology reproduces bar V_i and its variations reliably and the used bar V_i decompositions identify the underlying reasons behind observed bar V_i variations.

Klähn, Marco; Martin, Alistair; Cheong, Daniel W.; Garland, Marc V.

2013-12-01

18

[Partial molar pregnancy. A case report and literature review].  

PubMed

We report the case of a 17 year old patient with partial molar pregnancy and coexistent live fetus of 13 gestational weeks diagnosed by ultrasound, which required the termination of pregnancy for maternal decompensation. PMID:21966838

Morales García, Víctor; Bautista Gómez, Esperanza; Vásquez Santiago, Edmundo; Santos Pérez, Ursula

2011-07-01

19

The Partly Molar Pregnancy That Is Not a Partial Mole  

Microsoft Academic Search

The presence of a fetus in a molar pregnancy is usually an indication that it is a partial, rather than a complete, hydatidiform mole. The underlying reason for this is a basic difference in the genetic composition of the 2 types of mole. Complete moles are ‘‘androgenetic’’ conceptions, i.e., their genome is entirely paternal in origin [1]. The total absence

Harshwardhan M. Thaker

2005-01-01

20

Studies of viscosity and excess molar volume of binary mixtures  

Microsoft Academic Search

The excess molar volume VE viscosity deviation ??, excess viscosity ?ln ? and excess Gibbs energy of activation ?G*E of viscous flow have been investigated from the density ? and viscosity ? measurements of seven binary mixtures of propylamine with ethanol, propanol, butanol, pentanol, heptanol, octanol and decanol over the entire range of mole fractions at 303.15 and 313.15 K.

S. L Oswal; H. S Desai

1998-01-01

21

Reduced radiation-absorbed dose to tissues with partial panoramic radiography for evaluation of third molars  

SciTech Connect

The radiation-absorbed doses from panoramic radiography, distal molar radiography, and a partial panoramic radiographic technique that exposes only the third molar region to radiation are compared. Doses of radiation to the submandibular salivary gland were comparable by all three techniques, but doses of radiation to the head and neck were reduced greatly by the partial panoramic radiographic technique. Partial panoramic radiography is a diagnostically satisfactory and a radiologically safer technique for evaluation of third molar pathosis than is panoramic or distal molar radiography.

Kircos, L.T.; Eakle, W.S.; Smith, R.A.

1986-05-01

22

Part 2: Limiting apparent molar volume of organic and inorganic 1:1 electrolytes in (water + ethylammonium nitrate) mixtures at 298 K – Thermodynamic approach using Bahe–Varela pseudo-lattice theory  

Microsoft Academic Search

Values of partial molar volumes at infinite dilution of 9 inorganic and 4 organic 1:1 electrolytes have been determined in (water+ethylammonium nitrate) (EAN) binary at 298.15K throughout the composition scale. Our theoretical analysis shows that the values of partial molar volumes at infinite dilution of a solute in a binary are linked to those of the partial molar volumes of

Sabbah Bouguerra; Ibrahim Bou Malham; Pierre Letellier; Alain Mayaffre; Mireille Turmine

2008-01-01

23

Effect of temperature on the excess molar volumes of some alcohol + aromatic mixtures and modelling by cubic EOS mixing rules  

Microsoft Academic Search

Densities of the (methanol+benzene), (ethanol+benzene), (methanol+chlorobenzene) and (ethanol+chlorobenzene) mixtures have been measured at six temperatures (288.15, 293.15, 298.15, 303.15, 308.15 and 313.15K) and 101.33kPa. Excess molar volumes VE were determined and fitted by the Redlich–Kister equation. It was observed that in all cases VE increases with rising of temperature. The values of limiting excess partial molar volumes have been calculated,

Slobodan P. Šerbanovi?; Mirjana Lj. Kijev?anin; Ivona R. Radovi?; Bojan D. Djordjevi?

2006-01-01

24

Melt densities for leucogranites and granitic pegmatites: Partial molar volumes for SiO 2, Al 2O 3, Na 2O, K 2O, Li 2O, Rb 2O, Cs 2O, MgO, CaO, SrO, BaO, B 2O 3, P 2O 5, F 2O -1, TiO 2, Nb 2O 5, Ta 2O 5, and WO 3  

NASA Astrophysics Data System (ADS)

The densities and thermal expansivities of thirty-eight haplogranitic silicate melts have been experimentally determined. The compositions represent the additions of approximately 5, 10, and 20 wt% of selected oxide components Al 2O 3, Na 2O, K 2O, Li 2O, Rb 2O, Cs 2O, MgO, CaO, SrO, BaO, TiO 2, Nb 2O 5, Ta 2O 5, and WO 3 to a base melt of haplogranitic (HPG8) composition. The densities of melts have been obtained by a combination of scanning dilatometry and room temperature Archimedean density determinations together with scanning calorimetry. The thermal expansivities were obtained by a combination of scanning calorimetry and scanning dilatometry. The results of the density and expansivity determinations for the melts are fit to a multicomponent linear least squares regression of molar volume vs. molar composition. The resulting partial molar volumes of the molten oxides are reported for a reference temperature of 750°C. The multicomponent linear least squares regression yields a description of the database with a root mean squared deviation of 0.3%. The fit to these new partial molar volume data includes our previous data for B 2O 3, P 2O 5, and F 2O -1-bearing haplogranitic melts. The partial molar volumes of the oxides vary from 10.53 ± 0.29 cm 3 mole -1 for MgO to 69.09 ± 1.82 cm 3 mol -1 for P 2O 5. Compared on the basis of one oxygen per mole they range from 10.53 ± 0.29 cm 3 mol -1 (MgO) to 55.38 ± 1.69 cm 3 mol -1 (Cs 2O). The present data, taken together with an estimate of the partial molar volume of water in these melts (13.1 ± 1.3 cm 3 mol -1) are recommended to be used to calculate the low pressure densities of leucogranitic and pegmatitic melts.

Knoche, R.; Dingwell, D. B.; Webb, S. L.

1995-11-01

25

Sealing versus partial caries removal in primary molars: a randomized clinical trial  

PubMed Central

Background The resin-based pit and fissure sealant is considered a successful tool in caries prevention, however there is a growing evidence of its use in controlling already established caries in posterior teeth. The aim of this clinical trial is to verify the efficacy of pit and fissure sealants in arresting dentinal caries lesions compared to partial excavation and restorative treatment in primary molar teeth. Methods Thirty six patients with occlusal cavitated primary molar reaching outer half of dentin were selected. The patients were randomly allocated into two groups: sealant application (experimental group – n?=?17) and restoration with composite resin (control group – n?=?19). Clinical and radiograph evaluation were performed after 6, 12 and 18 months. The chi-square test was used to verify the distribution of characteristics variables of the sample among the groups. The survival rate of treatments was evaluated using Kaplan–Meier survival and log-rank test. Fisher’s Exact and logistic regression tests were calculated in each evaluation period (??=?5%). Results The control group showed significantly better clinical survival after 18 months (p?=?0.0025). In both groups, no caries progression was registered on the radiographic evaluations. Conclusions Sealing had similar efficacy in the arrestment of caries progression of cavitated occlusal lesions compared to partial excavation of the lesions, even though the frequency of re-treatments was significantly higher in sealed lesions. Trial registration Registro Brasileiro de Ensaios Clínicos (ReBEC): RBR-9kkv53

2014-01-01

26

The Component Slope Linear Model for Calculating Intensive Partial Molar Properties: Application to Waste Glasses and Aluminate Solutions - 13099  

SciTech Connect

Partial molar properties are the changes occurring when the fraction of one component is varied while the fractions of all other component mole fractions change proportionally. They have many practical and theoretical applications in chemical thermodynamics. Partial molar properties of chemical mixtures are difficult to measure because the component mole fractions must sum to one, so a change in fraction of one component must be offset with a change in one or more other components. Given that more than one component fraction is changing at a time, it is difficult to assign a change in measured response to a change in a single component. In this study, the Component Slope Linear Model (CSLM), a model previously published in the statistics literature, is shown to have coefficients that correspond to the intensive partial molar properties. If a measured property is plotted against the mole fraction of a component while keeping the proportions of all other components constant, the slope at any given point on a graph of this curve is the partial molar property for that constituent. Actually plotting this graph has been used to determine partial molar properties for many years. The CSLM directly includes this slope in a model that predicts properties as a function of the component mole fractions. This model is demonstrated by applying it to the constant pressure heat capacity data from the NaOHNaAl(OH){sub 4}-H{sub 2}O system, a system that simplifies Hanford nuclear waste. The partial molar properties of H{sub 2}O, NaOH, and NaAl(OH){sub 4} are determined. The equivalence of the CSLM and the graphical method is verified by comparing results determined by the two methods. The CSLM model has been previously used to predict the liquidus temperature of spinel crystals precipitated from Hanford waste glass. Those model coefficients are re-interpreted here as the partial molar spinel liquidus temperature of the glass components. (authors)

Reynolds, Jacob G. [Washington River Protection Solutions, LLC, P.O. Box 850, Richland, WA 99352 (United States)] [Washington River Protection Solutions, LLC, P.O. Box 850, Richland, WA 99352 (United States)

2013-07-01

27

Partial Molar Liquidus Temperatures of Multivalent Elements in Multicomponent Borosilicate Glass  

SciTech Connect

A multicomponent borosilicate glass containing several multivalent elements (Fe, Ni, Cr, Mn) and precipitating (Fe,Ni,Mn,Cr)(Fe,Cr,Mn)2O4 spinel as its primary phase, was equilibrated with the gas phase over the range of oxygen partial pressures, from 10{sup -13} Pa to 10{sup 5} Pa and temperatures, T, from 850 C to 1300 C. The oxidation-reduction equilibrium of Fe in the glass was measured with Mossbauer spectroscopy and wet colorimetry. These data were combined with oxidation-reduction equilibria for Fe, Ni, and Cr in a borosilicate frit of a similar composition found in the literature to estimate concentrations of Fe(II), Fe(III), Ni(II), Cr(II), Cr(III), and Cr(VI) as functions of T. Measured liquidus temperature (TL) data for the test glasses within the same range were then added to a critically evaluated TL database composed of multicomponent borosilicate glasses within the spinel primary crystalline phase field. The set of partial molar liquidus temperatures for elements other than oxygen determined from this database was then augmented by values for Fe(II), Fe(III), Cr(II), Cr(III), and Cr(VI). A 0.1-mol% change in the metal ion concentration increases TL as follows: Fe(II) by 4.6 C, Fe(III) by 2.8 C, Cr(II) by 185?C, Cr(III) by 66 C, and Cr(VI) by -17 C. The calculated TL based on partial molar liquidus temperatures agreed with the measured TL in the range from 10{sup -13} Pa to 10{sup 5} Pa.

Hrma, Pavel R. (BATTELLE (PACIFIC NW LAB)); Izak, Pavel (ASSOC WESTERN UNIVERSITY); Vienna, John D. (BATTELLE (PACIFIC NW LAB)); Thomas, M-L (.); Irwin, G M. (.)

2002-01-01

28

Partial molecular volumes of lipids and cholesterol  

PubMed Central

Volumetric measurements are reported for fully hydrated lipid/cholesterol bilayer mixtures using the neutral flotation method. Apparent specific volume data were obtained with the lipids DOPC, POPC and DMPC at T = 30 °C, DPPC at 50 °C, and brain sphingomyelin (BSM) at 45 and 24 °C for mole fractions of cholesterol x from 0 to 0.5. Unlike previous cholesterol mixture studies, we converted our raw data to partial molecular volume VL of the lipid and VC of the cholesterol. The partial molecular volumes were constant for POPC and DOPC as x was varied, but had sharp breaks for the other lipids at values of xC near 0.25 ± 0.05. Results for x < xC clearly exhibit the condensation effect of cholesterol on DPPC, DMPC and BSM when measured at temperatures above their main transition temperatures TM. The break points at xC are compared to phase diagrams in the literature. For x > xC the values of the partial molecular volumes of cholesterol clustered near 630 ± 10 Å3 in all the lipids when measured for T > TM; we suggest that this is the most appropriate measure of the bare volume of cholesterol in lipid bilayers.

Greenwood, Alexander I.; Tristram-Nagle, Stephanie; Nagle, John F.

2009-01-01

29

Determination of the Molar Volume of Hydrogen from the Metal-Acid Reaction: An Experimental Alternative.  

ERIC Educational Resources Information Center

Describes an alternative technique for determining the molar volume of hydrogen from the metal-acid reaction in which the metal sample is encased in a specially prepared cage and a pipette filler is used to fill an inverted burette with water. Eliminates some difficulties encountered with the conventional technique. (JRH)

de Berg, Kevin; Chapman, Ken

1996-01-01

30

Excess molar volumes and excess molar enthalpies of binary mixtures for 1,2-dichloropropane + 2-alkoxyethanol acetates at 298.15 K  

Microsoft Academic Search

The excess molar volumes VmE and excess molar enthalpies HmE over the whole range of composition have been measured for the binary mixtures formed by 1,2-dichloropropane (1,2-DCP) with three 2-alkoxyethanol acetates at 298.15K and atmospheric pressure using a digital vibrating-tube densimeter and an isothermal calorimeter with flow-mixing cell, respectively. The 2-alkoxyethanol acetates are ethylene glycol monomethyl ether acetate (EGMEA), ethylene

D. Sen; M. G. Kim

2008-01-01

31

Apparent molar volumes and compressibilities of tetrabutyl-ammonium bromide in organic solvents  

Microsoft Academic Search

The densities of tetra-n-butylammonium bromide in 1-propanol, 1-butanol, acetone at (288.15, 293.15, 298.15, 303.15, 308.15, 313.15, and 323.15)K and sound velocities at 298.15K have been measured. From these data apparent molar volumes V? at (288.15, 293.15, 298.15, 303.15, 308.15, 313.15, and 323.15)K and the apparent molar isenotropic compressibility KS,?, at T=298.15K of tetrabutylammonium bromide in nonaqueous solvents have been determined.

Joanna Krakowiak

2011-01-01

32

Excess molar volumes and viscosities of binary mixtures of diethylene glycol diethyl ether with chloroalkanes at 298.15 K  

Microsoft Academic Search

Excess molar volumes (VmE) and dynamic viscosities (?) at 298.15 K and atmospheric pressure for mixtures of diethylene glycol diethyl ether + dichloromethane, + trichloromethane, and + tetrachloromethane were determined as a function of composition. The excess molar volumes are all negative over the whole composition range. The deviations in viscosity (?ln?) and excess energies of activation (?G?E) for viscous

Amalendu Pal; Rakesh Kumar Bhardwaj

2003-01-01

33

Excess molar volumes, excess viscosities and refractive indices of a quaternary liquid mixture at 298.15 K  

Microsoft Academic Search

Density, viscosity and refractive index values for the propan-2-ol + methylacetate + dichloromethane + n-pentane mixture have been measured at 298.15 K, over the whole concentration range. Excess molar volumes and viscosities have been calculated. Flory's statistical theory has been applied to predict the excess molar volumes and compare then to the experimental data. We have also applied Grunberg and

Ernesto Caner; Graciela C. Pedrosa; Miguel Katz

1996-01-01

34

Changes in molar volume and heat capacity of actin upon polymerization.  

PubMed Central

We have used densimetry and microcalorimetry to measure the changes in molar volume and heat capacity of the actin molecule during Mg(2+)-induced polymerization. Molar volume is decreased by 720 ml/mol. This result is in contradiction with previous measurements by Ikkai and Ooi [(1966) Science 152, 1756-1757], and by Swezey and Somero [(1985) Biochemistry 24, 852-860]: both of these groups reported increases in actin volume during polymerization, of 391 ml/mol and 63 ml/mol respectively. We also observed a decrease in heat capacity of about 69.5 kJ.K-1.mol-1 during polymerization. This is in agreement with the concept of conformational fluctuation of proteins proposed by Lumry and Gregory [(1989) J.Mol. Liq. 42, 113-144]whereby either ligand binding by a protein or monomer-monomer interaction decreases the protein's conformational flexibility.

Quirion, F; Gicquaud, C

1993-01-01

35

Determination of the passive absorption through the rat intestine using chromatographic indices and molar volume.  

PubMed

Immobilized artificial membrane (IAM) chromatography coupled to physicochemical descriptors was evaluated to model the passive intestinal absorption of drugs through rat gut sacs. The chromatographic capacity factors (logk'(IAM)) of 12 structurally diverse compounds were determined on a IAM PC DD2 column. The passive permeabilities (P(a)) of the drugs were determined through rat everted gut sacs or through non-everted sacs for actively transported molecules. Correlation studies between logk'(IAM), physicochemical descriptors and P(a) were conducted by stepwise multiple linear regression (MLR) and back-propagation neural network (BPNN). MLR and BPNN showed that logk'(IAM) was the descriptor which correlated best with P(a). Considering the molar volume as an additional descriptor, the correlation was improved. Retention indices on IAM and the molar volume can be used concurrently to predict passive drug absorption. PMID:11113641

Genty, M; González, G; Clere, C; Desangle-Gouty, V; Legendre, J Y

2001-01-01

36

Molar volumes of molten indium at high pressures measured in a diamond anvil cell  

Microsoft Academic Search

Molar volumes of molten indium have been measured in an isothermal compression up to 8.5 GPa at 710(3) K in an externally heated diamond anvil cell. The measurement is based on the x-ray diffraction and x-ray absorption of materials using a synchrotron monochromatic x-ray microbeam. The fit to the results with the Birch-Murnaghan equation of state gives parameters of V0=16.80

Guoyin Shen; Nagayoshi Sata; Mathew Newville; Mark L. Rivers; Stephen R. Sutton

2002-01-01

37

Excess molar volumes of diisopropylamine + (C 1–C 5) alkan-1-ols: Application of the ERAS model and cubic EOS  

Microsoft Academic Search

Densities of the binary mixtures consist of methanol, ethanol, 1-propanol, 1-butanol and 1-pentanol with diisopropylamine were measured at temperatures (293.15, 298.15, 303.15 and 313.15) K and atmospheric pressure. Data were used to calculate the excess molar volumes. All the excess molar volumes are large and negative over the whole range of mole fraction, indicating strong interactions between unlike molecules. The

Mohammad Almasi; Maryam Shojabakhtiar

2011-01-01

38

Partial volume simulation in software breast phantoms  

NASA Astrophysics Data System (ADS)

A modification to our previous simulation of breast anatomy is proposed, in order to improve the quality of simulated projections generated using software breast phantoms. Anthropomorphic software breast phantoms have been used for quantitative validation of breast imaging systems. Previously, we developed a novel algorithm for breast anatomy simulation, which did not account for the partial volume (PV) of various tissues in a voxel; instead, each phantom voxel was assumed to contain single tissue type. As a result, phantom projection images displayed notable artifacts near the borders between regions of different materials, particularly at the skin-air boundary. These artifacts diminished the realism of phantom images. One solution is to simulate smaller voxels. Reducing voxel size, however, extends the phantom generation time and increases memory requirements. We achieved an improvement in image quality without reducing voxel size by the simulation of PV in voxels containing more than one simulated tissue type. The linear x-ray attenuation coefficient of each voxel is calculated by combining attenuation coefficients proportional to the voxel subvolumes occupied by the various tissues. A local planar approximation of the boundary surface is employed, and the skin volume in each voxel is computed by decomposition into simple geometric shapes. An efficient encoding scheme is proposed for the type and proportion of simulated tissues in each voxel. We illustrate the proposed methodology on phantom slices and simulated mammographic projections. Our results show that the PV simulation has improved image quality by reducing quantization artifacts.

Chen, Feiyu; Pokrajac, David; Shi, Xiquan; Liu, Fengshan; Maidment, Andrew D. A.; Bakic, Predrag R.

2012-02-01

39

Bubble curves and saturated liquid molar volumes for chlorofluorohydrocarbon-hydrocarbon mixtures: Experimental data and modeling  

SciTech Connect

Vapor-liquid equilibria and liquid densities were obtained using a static apparatus fitted with a variable-volume cell which was described in detail by Valtz et al. (1). Results are given at four temperatures for the binary systems butane--1,2,2-trichlorotrifluoroethane, pentane--1,2-dichloro-1,1,2,2-tetrafluoroethane, hexane--1,2-dichloro-1,1,2,2-tetrafluoroethane, heptane--1,12-trichloro-1,2,2-trifluoromethane, heptane--1,2-dichloro-1,1,2,2-tetrafluoroethane, and benzene--1,2-dichloro-1,1,2,2-tetrafluoroethane and the ternary system 1,2-dichloro-1,1,2,2-tetrafluoroethane--1,1,2-trichloro-1,2,2-trifluoromethane--heptane. The best simultaneous representation of pressures and saturated liquid molar volumes at a given temperature and liquid composition for these mixtures is obtained using either the Patel-Teja or Trebble-Bishnoi-Salim equation of state (TBS EOS) in either their standard or generalized form (maximum deviation 0.7% in pressure and 3.1% in saturated liquid molar volume with the TBS EOS).

Laugier, S. (Ecole Nationale Superieure de Chimie et Physique de Bordeaux, Talence (France)); Richon, D.; Renon, H. (Ecole National Superieure des Mines de Paris, Fontainebleau (France). Lab. de Thermodynamique)

1994-01-01

40

Molar Volume Dependence of Static Magnetization and Ordering Temperature in bcc Solid 3He  

NASA Astrophysics Data System (ADS)

Nuclear magnetic ordering in bcc 3He has been studied by a static magnetization measurement from 10 down to 0.3 mK for a molar volume region of V=24.14 to V=22.46 cm3/mole. The results show that the ordering temperature TN varies in proportion to V16.5+/-1 and that the magnetization in the ordered state is constant. The magnetization reduced by its maximum value is found to be represented by a universal function of the reduced temperature TTN.

Hata, T.; Yamasaki, S.; Taneda, M.; Kodama, T.; Shigi, T.

1983-10-01

41

Prediction of excess molar volumes of binary mixtures of organic compounds from refractive indices  

Microsoft Academic Search

The excess molar volumes of 51 binary mixtures containing diverse groups of organic compounds: alcohols (methanol, ethanol,\\u000a propan-1-ol, butan-1-ol, pentan-1-ol, hexan-1-ol, and heptan-1-ol), (cyclo-) alkanes (hexane, heptane, octane, nonane, decane,\\u000a undecane, dodecane, and cyclohexane), esters (diethyl carbonate and ethyl chloroacetate), aromatics (o-xylene, m-xylene, p-xylene, and ethylbenzene), ketones (acetone), and ethers (anisole), were predicted from the refractive index data, using\\u000a three

Ivona R. Radovi?; Mirjana Lj. Kijev?anin; Marijan Z. Gabrijel; Slobodan P. Šerbanovi?; Bojan D. Djordjevi?

2008-01-01

42

Volume rendering in the presence of partial volume effects.  

PubMed

In tomographic imagery, partial volume effects (PVEs) cause several artifacts in volume renditions. In X-ray computed tomography (CT), for example, soft-tissue-like pseudo structures appear in bone-to-air and bone-to-fat interfaces. Further, skin, which is identical to soft tissue in terms of CT number, obscures the rendition of the latter. The purpose of this paper is to demonstrate these phenomena and to provide effective solutions that yield significantly improved renditions. We introduce two methods that detect and classify voxels with PVE in X-ray CT. Further, a method is described to automatically peel skin so that PVE-resolved renditions of bone and soft tissue reveal considerably more detail. In the first method to address PVE, called the fraction measure (FM) method, the fraction of each tissue material in each voxel v is estimated by taking into account the intensities of the voxels neighboring v. The second method, called uncertainty principle (UP) method, is based on the following postulate (Saha and Udupa, 2001): In any acquired image, voxels with the highest uncertainty occur in the vicinity of object boundaries. The removal of skin is achieved by means of mathematical morphology. Volume renditions have been created before and after applying the methods for several patient CT datasets. A mathematical phantom experiment involving different levels of PVE has been conducted by adding different degrees of noise and blurring. A quantitative evaluation is done utilizing the mathematical phantom and clinical CT data wherein an operator carefully masked out voxels with PVE in the segmented images. All results have demonstrated the enhanced quality of display of bone and soft tissue after applying the proposed methods. The quantitative evaluations indicate that more than 98% of the voxels with PVE are removed by the two methods and the second method performs slightly better than the first. Further, skin peeling vividly reveals fine details in the soft tissue structures. PMID:15707248

Souza, Andre; Udupa, Jayaram K; Saha, Punam K

2005-02-01

43

Correction for Partial Volume Effects in PET: Principle and Validation  

Microsoft Academic Search

The accuracy of PET for measuring regional radiotracer concentra tions in the human brain is limited by the finite resolution capability of the scanner and the resulting partial volume effects (PVEs). We designed a new algorithm to correct for PVEs by characterizing the geometric interaction between the PETsystem and the brain activity distribution. Methods: The partial volume correction (PVC) algo

O. G. Rousset; Yilong Ma; Alan C. Evans

1998-01-01

44

Partial specific volume of methyl cellulose  

NASA Astrophysics Data System (ADS)

This document is part of Subvolume D2 'Polymer Solutions - Physical Properties and their Relations I (Thermodynamic Properties: PVT -Data and miscellaneous Properties of polymer Solutions) of Volume 6 `Polymers' of Landolt-Börnstein - Group VIII `Advanced Materials and Technologies'.

Wohlfarth, Ch.

45

Angiomatous malformation of placental chorionic stem vessels and pseudo-partial molar placentas: report of five cases.  

PubMed

Five placentas referred to the Michigan Placental Tissue Registry between 1982 and 1992 exhibited an unusual malformation of chorionic stem vessels. Multiple intestine-like tangles arising from umbilical vessels rested on and entered the chorionic plate. This anomaly appears similar to the "unusual vascular anomaly of the placenta" reported by Lee et al. (Am J Clin Pathol 1991; 95:48-51). In addition, amnionic-type bands were often adherent to the vascular complex. In three cases, clusters of macrocystic villi interspersed by normal placental parenchyma resulted in a partial molar appearance. Two of the infants were stillborn; three were liveborn. Congenital anomalies were not recognized in other organs. Flow cytometric analysis of placental tissue from four specimens disclosed a diploid chromosomal pattern. This rare anomaly complex appears to be a malformation involving the extraembryonic mesoderm rather than a cytogenetic error. PMID:8247960

Sander, C M

1993-01-01

46

Isothermal vapor–liquid equilibria and excess molar volumes for 2-methyl pyrazine (2MP) containing binary mixtures  

Microsoft Academic Search

2-Methyl pyrazine (2MP) has led to significant interest for its industrial and pharmaceutical uses. The new vapor–liquid equilibria (VLE) at 353.15K and excess molar volumes (VE) at 298.15K over the whole mole fraction range for seven binaries (water, n-hexane, cyclohexane, n-heptane, methylcyclopentane (MCP), methylcyclohexane (MCH) and ethyl acetate (EA) with 2MP) have been measured. VLE were measured by using headspace

So-Jin Park; Hyun-Hee Kim; Kyu-Jin Han; Dong-Bok Won; Sang Bong Lee; Myoung-Jae Choi

2001-01-01

47

Thermodynamics of aqueous methyldiethanolamine (MDEA) and methyldiethanolammonium chloride (MDEAH +Cl ?) over a wide range of temperature and pressure: Apparent molar volumes, heat capacities, and isothermal compressibilities  

Microsoft Academic Search

Apparent molar volumes of aqueous methyldiethanolamine and its salt were determined with platinum vibrating tube densitometers over a range of temperatures from 283K?T?576K and at pressures from 0.1MPa to 20MPa. Apparent molar heat capacities were obtained using a Sodev Picker flow microcalorimeter at a pressure of 0.1MPa and within the temperature range of 283K?T?328K. Apparent molar adiabatic and isothermal compressibilities

B. Hawrylak; R. Palepu; Peter R. Tremaine

2006-01-01

48

Apparent molar volumes of La(CF{sub 3}SO{sub 3}){sub 3}(aq) and Gd(CF{sub 3}SO{sub 3}){sub 3}(aq) at 278 K, 298 K, and 318 K at pressures to 30.0 MPa  

SciTech Connect

Densities of La(CF{sub 3}SO{sub 3}){sub 3}(aq) and Gd(CF{sub 3}SO{sub 3}){sub 3}(aq) have been measured at 278 K, 298 K, and 318 K at pressures of 0.1 MPa, 7.0 MPa, and 30.0 MPa using vibrating-tube densimeters. Apparent molar volumes obtained from the density data have been fitted to the Pitzer equation. The standard partial molar volumes V{sub {phi}}{sup {infinity}} and the ion-interaction parameters {beta}{sup (0)V} and {beta}{sup (1)V} have been determined through least-squares fitting to the experimental results. The standard partial molar volume of the trifluoromethanesulfonate anion V{sub {phi}}{sup {infinity}}(CF{sub 3}SO{sub 3}{sup {minus}},aq) was calculated at 298 K and 0.1 MPa from the partial molar volumes of the gadolinium and lanthanum salts and the available values for the standard partial molar volumes of the cations. Excellent agreement is obtained for V{sub {phi}}{sup {infinity}}(CF{sub 3}SO{sub 3}{sup {minus}},aq) calculated from the data for the two salts.

Xiao, C.; Tremaine, P.R. [Memorial Univ. of Newfoundland, St. John`s, Newfoundland (Canada). Dept. of Chemistry] [Memorial Univ. of Newfoundland, St. John`s, Newfoundland (Canada). Dept. of Chemistry; Simonson, J.M. [Oak Ridge National Lab., TN (United States). Chemical and Analytical Sciences Div.] [Oak Ridge National Lab., TN (United States). Chemical and Analytical Sciences Div.

1996-09-01

49

Unusual behavior of the aqueous solutions of gemini bispyridinium surfactants: apparent and partial molar enthalpies of the dimethanesulfonates.  

PubMed

Apparent and partial molar enthalpies at 298 K of the aqueous solutions of cationic gemini surfactants 1,1'-didodecyl-2,2'-dimethylenebispyridinium dimethanesulfonate (12-Py(2)-2-(2)Py-12 MS); 1,1'-didodecyl-2,2'-trimethylenebispyridinium dimethanesulfonate (12-Py(2)-3-(2)Py-12 MS); 1,1'-didodecyl-2,2'-tetramethylenebispyridinium dimethanesulfonate (12-Py(2)-4-(2)Py-12 MS); 1,1'-didodecyl-2,2'-octamethylenebispyridinium dimethanesulfonate (12-Py(2)-8-(2)Py-12 MS); 1,1'-didodecyl-2,2'-dodecamethylenebispyridinium dimethanesulfonate (12-Py(2)-12-(2)Py-12 MS) were measured as a function of concentration and are here reported for the first time. They show a very peculiar behavior as a function of the spacer length, not allowing for the determination of a -CH 2- group contribution when this group is added to the spacer. The curve of the compound with a four-carbon-atom-long spacer lies between those of the compound with a spacer of 2 and 3 carbon atoms, instead of that below the latter, as expected. This surprising behavior, never found before in the literature and different from that found for the more popular m- s- m-type bisquaternary ammonium gemini surfactants, could be explained by a conformation change of the molecule, caused by stacking interactions between the two pyridinium rings, mediated by the counterion and appearing at an optimum length of the spacer. The hypothesis is also supported by the data obtained from the surface tension vs log c curves, showing that A min, the minimum area taken at the air-water interface by the molecule, is significantly lower for 12-Py(2)-4-(2)Py-12 MS than that of the other compounds of the same homologous series, and that the same compound has a greater tendency to form micelles instead of adsorbing at the air/water interface. The evaluation of the micellization enthalpies, by means of a pseudophase transition model, agrees with the exposed trends. These results confirm the great crop of information that can be derived from the study of the solution thermodynamics of aggregate systems and in particular from the curves of apparent and molar enthalpies vs concentration. PMID:18767790

Fisicaro, Emilia; Compari, Carlotta; Biemmi, Mariano; Duce, Elenia; Peroni, Monica; Barbero, Nadia; Viscardi, Guido; Quagliotto, Pierluigi

2008-10-01

50

Hygrometer for Detecting Water in Partially Enclosed Volumes  

NASA Technical Reports Server (NTRS)

A portable hygrometer has been devised to implement a pre-existing technique for detecting water trapped in partially enclosed volumes that may be difficult to reach and cannot be examined directly. The technique is based on the fact that eventually the air in such a volume becomes saturated or nearly so. The technique is straightforward: One measures the relative humidity and temperature of both the ambient air and a sample of air from the enclosed volume. If the relative humidity of the sample is significantly greater than that of the ambient air and/or if the sample is at or close to the dew point, then it can be concluded that water is trapped in the volume. Of course, the success of this technique depends on the existence of an access hole through which one can withdraw some air from the enclosed volume.

Youngquist, Robert C.; Surma, Jan; Parks, Steve

2005-01-01

51

Molar volume, excess enthalpy, and Prigogine-Defay ratio of some silicate glasses with different (P,T) histories  

NASA Astrophysics Data System (ADS)

Structural relaxation in silicate glasses with different (p,T) histories was experimentally examined by differential scanning calorimetry and measurements of molar volume under ambient pressure. Temperature and pressure-dependent rates of changes in molar volume and generation of excess enthalpy were determined for sodium trisilicate, soda lime silicate, and sodium borosilicate (NBS) compositions. From the derived data, Prigogine-Defay ratios are calculated and discussed. Changes of excess enthalpy are governed mainly by changes in short-range structure, as is shown for NBS where boron coordination is highly sensitive to pressure. For all three glasses, it is shown how the relaxation functions that underlie volume, enthalpy, and structural relaxation decouple for changes in cooling rates and pressure of freezing, respectively. The magnitude of the divergence between enthalpy and volume may be related to differences in structural sensitivity to changes in the (p,V,T,t) space on different length scales. The findings suggest that the Prigogine-Defay ratio is related to the magnitude of the discussed decoupling effect.

Wondraczek, Lothar; Behrens, Harald

2007-10-01

52

Molar volume, excess enthalpy, and Prigogine-Defay ratio of some silicate glasses with different (P,T) histories.  

PubMed

Structural relaxation in silicate glasses with different (p,T) histories was experimentally examined by differential scanning calorimetry and measurements of molar volume under ambient pressure. Temperature and pressure-dependent rates of changes in molar volume and generation of excess enthalpy were determined for sodium trisilicate, soda lime silicate, and sodium borosilicate (NBS) compositions. From the derived data, Prigogine-Defay ratios are calculated and discussed. Changes of excess enthalpy are governed mainly by changes in short-range structure, as is shown for NBS where boron coordination is highly sensitive to pressure. For all three glasses, it is shown how the relaxation functions that underlie volume, enthalpy, and structural relaxation decouple for changes in cooling rates and pressure of freezing, respectively. The magnitude of the divergence between enthalpy and volume may be related to differences in structural sensitivity to changes in the (p,V,T,t) space on different length scales. The findings suggest that the Prigogine-Defay ratio is related to the magnitude of the discussed decoupling effect. PMID:17949169

Wondraczek, Lothar; Behrens, Harald

2007-10-21

53

P-V-T-x relationship for CO 2+C 4H 10 and CO 2+iC 4H 10 binary gas mixtures and the partial molar volume of C 4H 10 and iC 4H 10 at 360.00 K  

Microsoft Academic Search

The P-V-T-x relationship of three systems, pure carbon dioxide (CO2) and two binaries CO2+butane (C4H10) and CO2+isobutane (iC4H10), were measured with a constant volume method. The experimental temperature was set to be 360.00 K, and the range of pressure was from 1.0 to 10.5 MPa. For the mixtures, the mole fraction of either C4H10 or iC4H10 was prepared to be

Tomoya Tsuji; Shuichiro Tanaka; Toshihiko Hiaki

2004-01-01

54

Denoising arterial spin labeling MRI using tissue partial volume  

NASA Astrophysics Data System (ADS)

Arterial spin labeling (ASL) is a noninvasive MRI method that uses magnetically labeled blood to measure cerebral perfusion. Spatial resolution of ASL is relatively small and as a consequence perfusion from different tissue types is mixed in each pixel. An average ratio of gray matter (GM) to white matter (WM) blood flow is 3.2 to 1. Disregarding the partial volume effects (PVE) can thus cause serious errors of perfusion quantification. PVE also complicates spatial filtering of ASL images as apart from noise there is a spatial signal variation due to tissue partial volume. Recently, an algorithm for correcting PVE has been published by Asllani et al. It represents the measured magnetization as a sum of different tissue magnetizations weighted by their fractional volume in a pixel. With the knowledge of the partial volume obtained from a high-resolution MRI image, it is possible to separate the individual tissue contributions by linear regression on a neighborhood of each pixel. We propose an extension of this algorithm by minimizing the total-variation of the tissue specific magnetization. This makes the algorithm more flexible to local changes in perfusion. We show that this method can be used to denoise ASL images without mixing the WM and GM signal.

Petr, Jan; Ferre, Jean-Christophe; Gauvrit, Jean-Yves; Barillot, Christian

2010-03-01

55

Anisotropic Partial Volume CSF Modeling for EEG Source Localization  

PubMed Central

Electromagnetic source localization (ESL) provides non-invasive evaluation of brain electrical activity for neurology research and clinical evaluation of neurological disorders such as epilepsy. Accurate ESL results are dependent upon the use of patient-specific models of bioelectric conductivity. While the effects of anisotropic conductivities in the skull and white matter have been previously studied, little attention has been paid to the accurate modeling of the highly conductive cerebrospinal fluid (CSF) region. This study examines the effect that partial volume errors in CSF segmentations have upon the ESL bioelectric model. These errors arise when segmenting sulcal channels whose widths are similar to the resolution of the magnetic resonance (MR) images used for segmentation, as some voxels containing both CSF and grey matter cannot be definitively assigned a single label. These problems, particularly prevalent in pediatric populations, make voxelwise segmentation of CSF compartments a difficult problem. Given the high conductivity of CSF, errors in modeling this region my result in large errors in the bioelectric model. We introduce here a new approach for using estimates of partial volume fractions in the construction of patient specific bioelectric models. In regions where partial volume errors are expected, we use a layered gray matter-CSF model to construct equivalent anisotropic conductivity tensors. This allows us to account for the inhomogeneity of the tissue within each voxel. Using this approach, we are able to reduce the error in the resulting bioelectric models, as evaluated against a known high resolution model. Additionally, this model permits us to evaluate the effects of sulci modeling errors and quantify the mean error as a function of the change in sulci width. Our results suggest that both under and over-estimation of the CSF region leads to significant errors in the bioelectric model. While a model with fixed partial volume fraction is able to reduce this error, we see the largest improvement when using voxel specific partial volume estimates. Our cross-model analyses suggest that an approximately linear relationship exists between sulci error and the error in the resulting bioelectric model. Given the difficulty of accurately segmenting narrow sulcal channels, this suggests that our approach may be capable of improving the accuracy of patient specific bioelectric models by several percent, while introducing only minimal additional computational requirements.

Hyde, Damon E.; Duffy, Frank H.; Warfield, Simon K.

2012-01-01

56

Temperature dependence of the molar volumes of liquid and solid3He at melting pressure near T N  

NASA Astrophysics Data System (ADS)

For temperatures above the solid ordering temperature TN=0.934 mK, the molar volumes v1 and vs of liquid and solid3He at melting pressure, Pm are determined primarily by the melting pressure and the compressibility. However, in the vicinity of TN and below, vs(T) is influenced greatly by the expansion coefficient, which becomes large and negative. Using existing thermodynamic data, we find that vs(T) has a minimum at TN with a negative slope for T < TN. A constant-volume, all-solid sample starting at T=0 with the pressure just above Pm would begin to melt as TN is approached, becoming all-solid again somewhat above TN.

Ni, W.; Xia, J. S.; Adams, E. D.; Takano, Y.

1995-07-01

57

Relation between heat of vaporization, ion transport, molar volume, and cation-anion binding energy for ionic liquids.  

PubMed

A number of correlations between heat of vaporization (H(vap)), cation-anion binding energy (E(+/-)), molar volume (V(m)), self-diffusion coefficient (D), and ionic conductivity for 29 ionic liquids have been investigated using molecular dynamics (MD) simulations that employed accurate and validated many-body polarizable force fields. A significant correlation between D and H(vap) has been found, while the best correlation was found for -log(DV(m)) vs H(vap) + 0.28E(+/-). A combination of enthalpy of vaporization and a fraction of the cation-anion binding energy was suggested as a measure of the effective cohesive energy for ionic liquids. A deviation of some ILs from the reported master curve is explained based upon ion packing and proposed diffusion pathways. No general correlations were found between the ion diffusion coefficient and molecular volume or the diffusion coefficient and cation/anion binding energy. PMID:19689161

Borodin, Oleg

2009-09-10

58

Dynamical aspects of mixing schemes in ethanol-water mixtures in terms of the excess partial molar activation free energy, enthalpy, and entropy of the dielectric relaxation process  

NASA Astrophysics Data System (ADS)

Dielectric relaxation measurements on the ethanol-water mixture for the entire concentration range in very small increments were carried out using TDR in the frequency range from 300 MHz to 25 GHz at 20 °C, 22.5 °C, and 25 °C. The activation enthalpy ?H and entropy ?S for the mixtures were separated from the activation free energy ?G, and hence the excess partial molar activation free energy, enthalpy, and entropy for ethanol, ?GEAE, ?HEAE, and ?SEAE, and those for water, ?GWE, ?HWE, and ?SWE were calculated. The concentration dependence of these partial molar quantities shows the existence of two regions bound at X (molar fraction of ethanol) ~0.18. In the water-rich region of X<0.1, ?HEAE and ?SEAE take large positive values, exhibiting two sharp maxima at X=0.04 and X=0.08, which is clearly attributed to structural enhancement of the hydrogen bond network of water by ethanol, the so-called hydrophobic hydration. From a standpoint of dynamics, mixing schemes of ethanol and water around the two points X=0.04 and X=0.08 seem to be qualitatively different. On the other hand, in the region of X>0.18, the values of ?HEAE and ?SEAE take nearly zero. This means that ethanol molecules in the mixtures are in almost the same environment as those are in pure ethanol, forming chainlike clusters surrounded or exothermically attached to by water molecules.

Sato, Takaaki; Chiba, Akio; Nozaki, Ryusuke

1999-02-01

59

Phase equilibria modelling applied to fluid inclusions: Liquid-vapour equilibria and calculation of the molar volume in the CO 2?CH 4?N 2 system  

NASA Astrophysics Data System (ADS)

Quantitative use of fluid inclusions requires the determination of composition and molar volume. The molar volume can be calculated in the CO 2?CH 4?N 2 system from both the determination of the temperature of a L + V ? L ( orV) equilibrium if the composition is known independently, provided an equation of state (EOS) reproduces the P- V- T- X properties of each phase at equilibrium. This study is applicable to fluids for which the sequence of phase transition is Sco2 + L + V ? L + V ? L ( orV) at increasing temperature. The molar volume is determined by following a two-step algorithm: (1) the pressure is calculated from a two-parameter cubic EOS with interaction parameters optimised along experimental L- V isotherms; (2) the molar volume is then calculated by the correlation of LEE and KESLER (1975) with the pressure calculated in the first step. Projections of polybaric L- V isotherms in v- x diagrams of the CO 2?CH 4, CO 2?N 2, and CH 4?N 2 systems can be directly applied to fluid inclusion studies. In addition, it is shown that the molar volume of CO 2-rich fluids ( Xco2 > 0.6) in the ternary system can be estimated with sufficient accuracy using empirical formulae relating to the v- x diagrams of the CO 2?CH 4 and CO 2?N 2 binary systems.

Thiery, R.; Vidal, J.; Dubessy, J.

1994-02-01

60

Volumetry of human molars with flat panel-based volume CT in vitro  

Microsoft Academic Search

The flat panel-based volume computed tomography (fpVCT) is a new CT device applicable for experimental, three-dimensional evaluation of teeth at a resolution of about 150 ?m in the high contrast region. The aim of this study was to investigate whether fpVCT was suitable for quantification of the volumes of dental hard tissues and the root canal system to establish a new

Christian Hannig; Eva Krieger; Christian Dullin; Hans-Albert Merten; Thomas Attin; Eckhardt Grabbe; Gabert Heidrich

2006-01-01

61

Accurate colon residue detection algorithm with partial volume segmentation  

NASA Astrophysics Data System (ADS)

Colon cancer is the second leading cause of cancer-related death in the United States. Earlier detection and removal of polyps can dramatically reduce the chance of developing malignant tumor. Due to some limitations of optical colonoscopy used in clinic, many researchers have developed virtual colonoscopy as an alternative technique, in which accurate colon segmentation is crucial. However, partial volume effect and existence of residue make it very challenging. The electronic colon cleaning technique proposed by Chen et al is a very attractive method, which is also kind of hard segmentation method. As mentioned in their paper, some artifacts were produced, which might affect the accurate colon reconstruction. In our paper, instead of labeling each voxel with a unique label or tissue type, the percentage of different tissues within each voxel, which we call a mixture, was considered in establishing a maximum a posterior probability (MAP) image-segmentation framework. A Markov random field (MRF) model was developed to reflect the spatial information for the tissue mixtures. The spatial information based on hard segmentation was used to determine which tissue types are in the specific voxel. Parameters of each tissue class were estimated by the expectation-maximization (EM) algorithm during the MAP tissue-mixture segmentation. Real CT experimental results demonstrated that the partial volume effects between four tissue types have been precisely detected. Meanwhile, the residue has been electronically removed and very smooth and clean interface along the colon wall has been obtained.

Li, Xiang; Liang, Zhengrong; Zhang, PengPeng; Kutcher, Gerald J.

2004-05-01

62

Surface tension and excess molar volumes of trimethyl benzene with tetrahydrofuran, tetra chloromethane and dimethyl sulfoxide  

NASA Astrophysics Data System (ADS)

Surface tension and excess volume for trimethyl benzene with tetrahydrofuran, tetra chloromethane, and diethyl solfoxide were theoretically predicted with the help of the Prigogine-Flory-Patterson (PFP) model over the entire concentration range at 298.15 K, which has immense sense of applicability in organic separation and synthesis as solvent. Further, we found that computed results are in good agreement with the experimental findings. The results so obtained have been explained on the basis of packing effect and dipolar-dipolar interactions. An attempt has also been made to study the excess thermodynamic functions that measure the extent of molecular interactions involved in the liquid mixture.

Shukla, R. K.; Dwivedi, Vatsala; Kumar, Atul; Srivastava, Urvashi

2010-10-01

63

Improved prediction of octanol-water partition coefficients from liquid-solute water solubilities and molar volumes  

USGS Publications Warehouse

A volume-fraction-based solvent-water partition model for dilute solutes, in which the partition coefficient shows a dependence on solute molar volume (V??), is adapted to predict the octanol-water partition coefficient (K ow) from the liquid or supercooled-liquid solute water solubility (Sw), or vice versa. The established correlation is tested for a wide range of industrial compounds and pesticides (e.g., halogenated aliphatic hydrocarbons, alkylbenzenes, halogenated benzenes, ethers, esters, PAHs, PCBs, organochlorines, organophosphates, carbamates, and amidesureas-triazines), which comprise a total of 215 test compounds spanning about 10 orders of magnitude in Sw and 8.5 orders of magnitude in Kow. Except for phenols and alcohols, which require special considerations of the Kow data, the correlation predicts the Kow within 0.1 log units for most compounds, much independent of the compound type or the magnitude in K ow. With reliable Sw and V data for compounds of interest, the correlation provides an effective means for either predicting the unavailable log Kow values or verifying the reliability of the reported log Kow data. ?? 2005 American Chemical Society.

Chiou, C. T.; Schmedding, D. W.; Manes, M.

2005-01-01

64

A molecular dynamics study of ambient and high pressure phases of silica: Structure and enthalpy variation with molar volume.  

PubMed

Extensive molecular dynamics studies of 13 different silica polymorphs are reported in the isothermal-isobaric ensemble with the Parrinello-Rahman variable shape simulation cell. The van Beest-Kramer-van Santen (BKS) potential is shown to predict lattice parameters for most phases within 2%-3% accuracy, as well as the relative stabilities of different polymorphs in agreement with experiment. Enthalpies of high-density polymorphs - CaCl2-type, ?-PbO2-type, and pyrite-type - for which no experimental data are available as yet, are predicted here. Further, the calculated enthalpies exhibit two distinct regimes as a function of molar volume-for low and medium-density polymorphs, it is almost independent of volume, while for high-pressure phases a steep dependence is seen. A detailed analysis indicates that the increased short-range contributions to enthalpy in the high-density phases arise not only from an increased coordination number of silicon but also shorter Si-O bond lengths. Our results indicate that amorphous phases of silica exhibit better optimization of short-range interactions than crystalline phases at the same density while the magnitude of Coulombic contributions is lower in the amorphous phase. PMID:24985659

Rajappa, Chitra; Sringeri, S Bhuvaneshwari; Subramanian, Yashonath; Gopalakrishnan, J

2014-06-28

65

Partial volume correction in SPECT reconstruction with OSEM  

NASA Astrophysics Data System (ADS)

SPECT images suffer from poor spatial resolution, which leads to partial volume effects due to cross-talk between different anatomical regions. By utilising high-resolution structural images (CT or MRI) it is possible to compensate for these effects. Traditional partial volume correction (PVC) methods suffer from various limitations, such as correcting a single region only, returning only regional mean values, or assuming a stationary point spread function (PSF). We recently presented a novel method in which PVC was combined with the reconstruction process in order to take into account the distance dependent PSF in SPECT, which was based on filtered backprojection (FBP) reconstruction. We now present a new method based on the iterative OSEM algorithm, which has advantageous noise properties compared to FBP. We have applied this method to a series of 10 brain SPECT studies performed on healthy volunteers using the DATSCAN tracer. T1-weighted MRI images were co-registered to the SPECT data and segmented into 33 anatomical regions. The SPECT data were reconstructed using OSEM, and PVC was applied in the projection domain at each iteration. The correction factors were calculated by forward projection of a piece-wise constant image, generated from the segmented MRI. Images were also reconstructed using FBP and standard OSEM with and without resolution recovery (RR) for comparison. The images were evaluated in terms of striatal contrast and regional variability (CoV). The mean striatal contrast obtained with OSEM, OSEM-RR and OSEM-PVC relative to FBP were 1.04, 1.42 and 1.53, respectively, and the mean striatal CoV values are 1.05, 1.53, 1.07. Both OSEM-RR and OSEM-PVC results in images with significantly higher contrast as compared to FBP or OSEM, but OSEM-PVC avoids the increased regional variability of OSEM-RR due to improved structural definition.

Erlandsson, Kjell; Thomas, Ben; Dickson, John; Hutton, Brian F.

2011-08-01

66

Evaluation of accuracy in partial volume analysis of small objects  

NASA Astrophysics Data System (ADS)

Accurate and robust assessment of quantitative parameters is a key issue in many fields of medical image analysis, and can have a direct impact on diagnosis and treatment monitoring. Especially for the analysis of small structures such as focal lesions in patients with MS, the finite spatial resolution of imaging devices is often a limiting factor that results in a mixture of different tissue types. We propose a new method that allows an accurate quantification of medical image data, focusing on a dedicated model for partial volume (PV) artifacts. Today, a widely accepted model assumption is that of a uniformly distributed linear mixture of pure tissues. However, several publications have clearly shown that this is not an appropriate choice in many cases. We propose a generalization of current PV models based on the Beta distribution, yielding a more accurate quantification. Furthermore, we present a new classification scheme. Prior knowledge obtained from a set of training data allows a robust initial estimate of the proper model parameters, even in cases of objects with predominant PV artifacts. A maximum likelihood based clustering algorithm is employed, resulting in a robust volume estimate. Experiments are carried out on more than 100 stylized software phantoms as well as on realistic phantom data sets. A comparison with current mixture models shows the capabilities of our approach.

Rexilius, Jan; Peitgen, Heinz-Otto

2008-04-01

67

Density and Molar Volume of Melts in the Systems LiCl-NaCl, NaCl-RbCl and NaCl-CsCl.  

National Technical Information Service (NTIS)

The densities of molten NaCl-CsCl, NaCl-RbCl and LiCl-NaCl systems were measured by the hydrostatic weighing method over the entire concentration range. The molar volumes and their deviations from additivity at 800 and 850C were calculated from the experi...

M. V. Smirnov V. P. Stepanov T. Mukatov

1973-01-01

68

The impact of oxygen nonstoichiometry upon partial molar thermodynamic quantities in PrBaCo2O5+?  

NASA Astrophysics Data System (ADS)

The coulometric titration data are utilized in order to calculate changes of oxygen partial entropy and enthalpy in PrBaCo2O with variations of oxygen content and temperature. The thermodynamic equilibrium of the cobaltite with the ambient gas phase is analyzed based on the interface of oxygen exchange and oxidation, and the intrinsic reaction of thermal excitation of Co3+ cations. The partial thermodynamic functions of the movable oxygen in PrBaCo2O are shown to be interrelated with the thermodynamic parameters of the defect formation reactions. The existence of a band gap of about 0.4 eV in the electronic spectrum of the cobaltite follows from a favorable comparison of the calculated and experimental dependencies of the partial thermodynamic functions of the movable oxygen.

Suntsov, A. Yu.; Leonidov, I. A.; Patrakeev, M. V.; Kozhevnikov, V. L.

2014-05-01

69

The Molar Volume of FeO-MgO-Fe2O3-Cr2O3-Al2O3-TiO2 Spinels  

NASA Astrophysics Data System (ADS)

A new model of molar volume has been calibrated in the spinel supersystem (Mg,Fe2+)(Al,Cr,Fe3+)2O4 - (Mg,Fe2+)2TiO4. A total of 832 X-ray and neutron diffraction experiments performed on spinels at ambient and in situ high-P, T conditions (from the American Mineralogist Crystal Structure Database (Downs and Hall-Wallace, 2003) and other sources) were used to calibrate end-member equations of state and an excess volume model for this system. The effect on molar volume of cation ordering over the octahedral and tetrahedral sites is captured with linear dependence on Mg2+, Al3+, and Fe3+ site occupancy terms. We allowed standard state volumes and coefficients of thermal expansion of the end members to vary within their uncertainties during extraction of the mixing properties, in order to achieve the best fit. Published equations of states of the various spinel end members were analyzed to obtain optimal values of the bulk modulus and its pressure derivative, for each explicit end member. For any spinel composition in the supersystem, the model molar volume is obtained by adding excess volume and cation order-dependent terms to a linear combination of the five end member volumes, estimated at pressure and temperature using the high-T Vinet equation of state. The model has a total of 31 parameters and fits nearly all experiments to within 0.02 J/bar/mol, or better than 0.5% in volume. The model is compared to the current MELTS (Ghiorso and Sack, 1995; Ghiorso et al., 2002) spinel model with a demonstration of the impact of the model difference on the estimated spinel-garnet lherzolite transition pressure. Our primary motivation in this work is the development of a comprehensive spinel molar volume model for use in calibration of activity-composition models of garnet and pyroxene solid solutions. The thermodynamic models, along with a new silicate liquid equation of state, will be incorporated into the next generation MELTS model, xMELTS. The new solid solution models will include some minor components, including Ti4+ and Cr3+. Because most constraints on the activity of garnet and pyroxene at high-P are derived from experiments with coexisting spinel, we must be confident in the ability of our spinel model to realistically reproduce thermodynamic behavior over all applicable compositions. Additionally, producing a spinel molar volume model calibrated with recent in situ high-P, T diffraction data is crucial to our ability to accurately model the spinel-garnet transition in Earth's upper mantle. For example, we recently calibrated Cr-Al exchange equilibria for garnet and spinel. When this new calibration is used with the current MELTS model, a region of garnet-spinel coexistence in lherzolites is predicted with width in pressure comparable to experimental constraints. The transition occurs, however, at the unexpectedly low pressure of ~1.7 GPa. The improved model of spinel molar volume presented here, along with a new garnet molar volume model in the system FeO-MgO-CaO-Fe2O3-Cr2O3-Al2O3-TiO2-Na2O-SiO2 currently being calibrated, will enable coupled recalibration of the garnet and pyroxene models to match both the absolute pressure and width of this key transition in mantle lithology.

Hamecher, E. A.; Antoshechkina, P. M.; Ghiorso, M. S.; Asimow, P. D.

2011-12-01

70

Temperature Dependence of Densities and Excess Molar Volumes of the Ternary Mixture (1-Butanol + Chloroform + Benzene) and its Binary Constituents (1-Butanol + Chloroform and 1-Butanol + Benzene)  

NASA Astrophysics Data System (ADS)

Densities ? of the 1-butanol + chloroform + benzene ternary mixture and the 1-butanol + chloroform and 1-butanol + benzene binaries have been measured at six temperatures (288.15, 293.15, 298.15, 303.15, 308.15, and 313.15) K and atmospheric pressure, using an oscillating U-tube densimeter. From these densities, excess molar volumes ( V E) were calculated and fitted to the Redlich Kister equation for all binary mixtures and to the Nagata and Tamura equation for the ternary system. The Radojkovi? et al. equation has been used to predict excess molar volumes of the ternary mixtures. Also, V E data of the binary systems were correlated by the van der Waals (vdW1) and Twu Coon Bluck Tilton (TCBT) mixing rules coupled with the Peng Robinson Stryjek Vera (PRSV) equation of state. The prediction and correlation of V E data for the ternary system were performed by the same models.

Smiljani?, Jelena D.; Kijev?anin, Mirjana Lj.; Djordjevi?, Bojan D.; Grozdani?, Dušan K.; Šerbanovi?, Slobodan P.

2008-04-01

71

Excess molar volumes of (hydrocarbon + ethyl 1,1-dimethylpropyl ether) at T = (298.15 and 308.15) K  

Microsoft Academic Search

The excess molar volumes VmEhave been measured as a function of mole fraction at T= (298.15 and 308.15) K and atmospheric pressure for each of 12 binary mixtures: (hexane, or cyclohexane, or benzene, or heptane, or 1-heptene, or 1-heptyne, or octane, or 2,2,4-trimethylpentane, or decane, or dodecane, or tetradecane, or hexadecane + ethyl 1,1-dimethylpropyl ether). The results were compared to

Urszula Domanska; Joanna Lachwa

2000-01-01

72

Temperature Dependence of Densities and Excess Molar Volumes of the Ternary Mixture (1Butanol + Chloroform + Benzene) and its Binary Constituents (1Butanol + Chloroform and 1Butanol + Benzene)  

Microsoft Academic Search

Densities rho of the 1-butanol + chloroform + benzene ternary mixture and the 1-butanol + chloroform and 1-butanol + benzene binaries have been measured at six temperatures (288.15, 293.15, 298.15, 303.15, 308.15, and 313.15) K and atmospheric pressure, using an oscillating U-tube densimeter. From these densities, excess molar volumes ( V E) were calculated and fitted to the Redlich Kister

Jelena D. Smiljanic; Mirjana Lj. Kijevcanin; Bojan D. Djordjevic; Dusan K. Grozdanic; Slobodan P. Serbanovic

2008-01-01

73

Applicability of cubic equation of state mixing rules on correlation of excess molar volume of non-electrolyte binary mixtures – Part II  

Microsoft Academic Search

The excess molar volume (V?) data of the 24 binary highly non-ideal mixtures containing dicyclic ethers (593 data points) were correlated by the Peng–Robinson–Stryjek–Vera (PRSV) cubic equation of state (CEOS) coupled with two different classes of mixing rules: (i) the composition dependent van der Waals (vdW) mixing rule and (ii) the excess free energy mixing rules (CEOS\\/G?) based on the

Mirjana L. J. Kijev?anin; Bojan D. Djordjevi?; Slobodan P. Šerbanovi?; Ivona R. Radovi?; Aleksandar Ž. Tasi?

2006-01-01

74

1Butanol + hexylamine + n-heptane at temperature range (288.15–323.15 K): Experimental density data, excess molar volumes determination and modeling with cubic EOS  

Microsoft Academic Search

Densities ? of the ternary system 1-butanol+hexylamine+n-heptane and binaries: 1-butanol+hexylamine and hexylamine+n-heptane within the temperature range (288.15–323.15K) and atmospheric pressure are reported. Excess molar volumes VE were calculated from the density data and fitted by the Redlich–Kister and Nagata and Tamura equations. The results are analyzed in terms of the molecular interactions between the components of mixtures.Several empirical relationships (Radojkovic,

Ivona R. Radovi?; Mirjana Lj. Kijev?anin; Slobodan P. Šerbanovi?; Bojan D. Djordjevi?

2010-01-01

75

Partial-volume Bayesian classification of material mixtures in MR volume data using voxel histograms.  

PubMed

We present a new algorithm for identifying the distribution of different material types in volumetric datasets such as those produced with magnetic resonance imaging (MRI) or computed tomography (CT). Because we allow for mixtures of materials and treat voxels as regions, our technique reduces errors that other classification techniques can create along boundaries between materials and is particularly useful for creating accurate geometric models and renderings from volume data. It also has the potential to make volume measurements more accurately and classifies noisy, low-resolution data well. There are two unusual aspects to our approach. First, we assume that, due to partial-volume effects, or blurring, voxels can contain more than one material, e.g., both muscle and fat; we compute the relative proportion of each material in the voxels. Second, we incorporate information from neighboring voxels into the classification process by reconstructing a continuous function, rho(x), from the samples and then looking at the distribution of values that rho(x) takes on within the region of a voxel. This distribution of values is represented by a histogram taken over the region of the voxel; the mixture of materials that those values measure is identified within the voxel using a probabilistic Bayesian approach that matches the histogram by finding the mixture of materials within each voxel most likely to have created the histogram. The size of regions that we classify is chosen to match the spacing of the samples because the spacing is intrinsically related to the minimum feature size that the reconstructed continuous function can represent. PMID:9617909

Laidlaw, D H; Fleischer, K W; Barr, A H

1998-02-01

76

Partial specific volume of cellulose N-phenyl carbamate  

NASA Astrophysics Data System (ADS)

This document is part of Subvolume D2 'Polymer Solutions - Physical Properties and their Relations I (Thermodynamic Properties: PVT -Data and miscellaneous Properties of polymer Solutions) of Volume 6 `Polymers' of Landolt-Börnstein - Group VIII `Advanced Materials and Technologies'.

Wohlfarth, Ch.

77

Excess molar volumes and viscosity deviations of the ternary system of 1-butanol + 2-butanol + 1,3-butanediol at 303.15 K  

Microsoft Academic Search

\\u000a Abstract  The viscosity and density of ternary mixtures of 1-butanol + 2-butanol + 1,3-butanediol and the binary systems 1-butanol + 2-butanol,\\u000a 1-butanol + 1,3-butanediol, and 2-butanol + 1,3-butanediol were measured at 303.15 K and atmospheric pressure over the entire\\u000a range of compositions. Excess molar volumes V\\u000a E and viscosity deviations ?? were obtained from the experimental results for the binary and ternary systems and fitted to\\u000a Redlich–Kister’s and Cibulka’s equations in terms

M. Rezaei-Sameti; H. Iloukhani

2009-01-01

78

Densities, Excess Molar Volumes, Viscosities, and Refractive Indices of Binary Mixtures of n-Butyl Acetate with 1-Chloroalkanes (C4-C8) at 298.15 K  

NASA Astrophysics Data System (ADS)

Densities, viscosities, and refractive indices of binary mixtures of n-butyl acetate (1) +1-chlorobutane (2), +1-chloropentane (2), +1-chlorohexane (2), +1-chloroheptane (2), and +1-chlorooctane (2) were measured at 298.15 K for the liquid region and at ambient pressure for the whole composition range. The excess molar volumes V E were calculated from experimental densities. McAllister's three-body interaction, and Hind and Grunberg-Nissan models are used for correlating the viscosity of binary mixtures. The experimental data of binaries are analyzed to discuss the nature and strength of intermolecular interactions in these mixtures.

Iloukhani, H.; Khanlarzadeh, K.; Rakhshi, M.

2011-03-01

79

FMDP Reactor Alternative Summary Report: Volume 3 - partially complete LWR alternative  

SciTech Connect

The Department of Energy Office of Fissile Materials Disposition (DOE/MD) initiated a detailed analysis activity to evaluate each of ten plutonium disposition alternatives that survived an initial screening process. This document, Volume 3 of a four volume report summarizes the results of these analyses for the partially complete LWR (PCLWR) reactor based plutonium disposition alternative.

Greene, S.R.; Fisher, S.E.; Bevard, B.B. [and others

1996-09-01

80

Thermodynamics of ionization of water at temperatures 278.15 ???T \\/ K ??? 393.15 and at the pressure p = 0.35 MPa: apparent molar volumes and apparent molar heat capacities of aqueous solutions of potassium and sodium nitrates and nitric acid  

Microsoft Academic Search

The apparent molar volumes V?and apparent molar heat capacitiesCp, ? of aqueous solutions of potassium and sodium nitrate and of nitric acid have been determined over the temperature range 278.15 ?T\\/K? 393.15 and molality range 0.015 ?m\\/ (mol · kg?1) ? 0.5 at the pressure p= 0.35 MPa. Densities of these solutions were measured using a vibrating-tube densimeter (DMA 512,

B. A. Patterson; E. M. Woolley

2002-01-01

81

Partial US oil, gas resource volumes termed astonishing'  

SciTech Connect

Land and state waters of the US contain technically recoverable volumes of 112.6 billion bbl of oil and 1,073.8 tcf of conventional and unconventional gas, the US Geological Survey estimated. The oil figure is 44% higher than the USGS assessed in its last study, released in 1989. The assessed 715 tcf of technically recoverable conventional gas reserves, expected reserve growth, and undiscovered accumulations is nearly 42% higher than the 1989 assessment. Moreover, the USGS for the first time assessed a further 300 tcf of technically recoverable gas in continuous-type largely unconventional deposits in sandstones, shales, and chalks, and almost another 50 tcf in coal beds. USGS estimated that 60 billion bbl will be added to the oil reserves and 322 tcf to the oil reserves and 322 tcf to the gas reserves of existing fields by way of revisions, extensions, and new pool discoveries during the 80 years following 1991. The estimates assume use of existing technology, and ignore barriers to leasing of onshore federal lands. The paper describes the results more fully.

Petzet, G.A.

1995-03-06

82

Retrospective processing of DTI tractography to compensate for partial volume effects  

NASA Astrophysics Data System (ADS)

Partial volume effects are one of the most common sources of error in diffusion tensor imaging (DTI) tractography. For example, in data from older subjects or Alzheimer's disease probable subjects, the situation is especially exacerbated around the dilated ventricle, which causes erroneous merging of tracts. Rescanning the subject at higher resolution is the best solution, but often times unattainable. We offer a retrospective filtering algorithm, which is purely subtractive, based on a region of interest (ROI) filtering methodology that filters tracts by their shape and seed points. The ROIs are defined using both anatomic images and fractional anisotropy (FA) maps in normalized space allowing for consistency across all subjects. Our algorithm helps correct the partial volume effects by reducing the overestimation of tract length, giving a more accurate regional tract count. The objective of our retrospective algorithm is reclamation of data sets from partial volume effects.

Hwang, Darryl; Shetty, Aarti; Rajagopalan, Amrita; Singh, Manbir

2007-03-01

83

Solubility and partial molar volume of carbon dioxide and ethane in crosslinked poly(ethylene oxide) copolymer  

Microsoft Academic Search

Experimental solubility and sorptive dilation data are reported for carbon dioxide and ethane in a crosslinked poly(ethylene oxide) (XLPEO) rubbery copolymer. Five differ- ent temperatures (253 ? T (K) ? 308) were considered, with a maximum gas pressure of 2.09 MPa (20.6 atm). The polymer was prepared by photopolymerization of a solution containing 70 wt % poly(ethylene glycol) methyl ether

Cláudio P. Ribeiro; Benny D. Freeman

2010-01-01

84

Molar heat capacity at constant volume of difluoromethane (R32) and pentafluoroethane (R125) from the triple-point temperature to 345 K at pressures to 35 MPa  

NASA Astrophysics Data System (ADS)

Molar heat capacities at constant volume ( C v) of dill uoromethane (R32) and pentalluoroethane (R125) were measured with an adiabatic calorimeter. Temperatures ranged from their triple points to 345 K, and pressures up to 35 MPa. Measurements were conducted on the liquid in equilibrium with its vapor and on compressed liquid samples. The samples were of a high purity, verified by chemical analysis of each fluid. For the samples, calorimetric results were obtained for two-phase ( C {v/(2)}), saturated liquid ( C ? or C' x ), and singlephase ( C v) molar heat capacities. The C ? data were used to estimate vapor pressures for values less than 0.3 MPa by applying a thermodynamic relationship between the saturated liquid heat capacity and the temperature derivatives of the vapor pressure. The triple-point temperature ( T tr) and the enthalpy of fusion (?fus H) were also measured for each substance. The principal sources of uncertainty are the temperature rise measurement and the change-ofvolume work adjustment. The expanded uncertainty (at the two-sigma level) for C v is estimated to be 0.7%, for C {v/(2)} it is 0.5%, and for C ? it is 0.7%.

Lüddecke, T. O.; Magee, J. W.

1996-07-01

85

The variation of viscosity, refractive indices, compressibility, intermolecular free length, and excess molar volume of the acetophenone—ethyl acetate solutions at 303.15-323.15 K  

NASA Astrophysics Data System (ADS)

Densities, viscosities, refractive indices and ultrasonic velocities of the binary mixtures of acetophenone with ethyl acetate were measured over the entire mole fractions at 303.15, 313.15, and 323.15 K. From the experimental results, excess molar volumes V E, viscosity deviation ??, refractive index deviation ? n D , deviations in isentropic compressibility ?? s and excess intermolecular free length ? L f are calculated. The viscosity values were fitted to the models of Krishnan-Laddha and McAllister. The thermophysical properties under study were fit to the Jouyban-Acree model. The excess values were correlated using Redlich-Kister polynomial equation to obtain their coefficients and standard deviations. The data obtained fitted with the values correlated by the corresponding models very well. The results are interpreted in terms of molecular interactions occurring in the solution.

Saravanakumar, K.; Baskaran, R.; Kubendran, T. R.

2012-12-01

86

Molar and excess volumes of liquid In-Sb, Mg-Sb, and Pb-Sb alloys  

SciTech Connect

By a direct Archimedes' technique, volumetric data were obtained for liquid In, Mg, Pb, and Sb and mixtures of In-Sb, Mg-Sb, and Pb-Sb. In this paper the excess volumes for the alloys studied are presented and discussed.

Hansen, A.R.; Kaminski, M.A. (Dept. of Chemical Engineering, Univ. of Illinois, Urbana, IL (US)); Eckert, C.A. (School of Chemical Engineering, Georgia Inst. of Technology, Atlanta, GA (US))

1990-04-01

87

A Modified Probabilistic Neural Network for Partial Volume Segmentation in Brain MR Image  

Microsoft Academic Search

A modified probabilistic neural network (PNN) for brain tissue segmentation with magnetic resonance imaging (MRI) is proposed. In this approach, covariance matrices are used to replace the singular smoothing factor in the PNN's kernel function, and weighting factors are added in the pattern of summation layer. This weighted probabilistic neural network (WPNN) classifier can account for partial volume effects, which

Tao Song; Mo M. Jamshidi; Roland R. Lee; Mingxiong Huang

2007-01-01

88

Partial Volume Correction Using Continuous Wavelet Technique in Small Animal PET Imaging  

Microsoft Academic Search

The underestimation of the emitted radioactivity in small tissue structures measured with PET unfortunately requires correction for the partial volume effect (PVE) prior to image analysis. Meanwhile, the continuous wavelet transform (CWT) has the potential to isolate the signal of small structures from their environments, and to determine each structure by its width and position in PET images. Using CWT

Lahcen Arhjoul; Otman Sarrhini; M. Bentourkia

2006-01-01

89

Using Microcomputers in the Physical Chemistry Laboratory: A Partial Molal Volumes Experiment.  

ERIC Educational Resources Information Center

Describes a computer program used in an experiment in which the partial molal volumes of sodium chloride solutions are calculated as a function of concentration from densities measured with a pycnometer. The complete program listing (also available from the author on disk) and a sample run are included. (JN)

Venugopalan, Mundiyath

1986-01-01

90

An MR image-guided, voxel-based partial volume correction method for PET images  

PubMed Central

Purpose: Partial volume effect in positron emission tomography (PET) can cause incorrect quantification of radiopharmaceutical uptake in functional imaging. A PET partial volume correction method is presented to attenuate partial volume blurring and to yield voxel-based corrected PET images. Methods: By modeling partial volume effect as a convolution of point spread function of the PET scanner, the reconstructed PET images are corrected by iterative deconvolution with an edge-preserving smoothness constraint. The constraint is constructed to restore discontinuities extracted from coregistered MR images but maintains the smoothness in radioactivity distribution. The correction is implemented in a Bayesian deconvolution framework and is solved by a conjugate gradient method. The performance of the method was compared with the geometric transfer matrix (GTM) method on a simulated dataset. The method was evaluated on synthesized brain FDG–PET data and phantom MRI–PET experiments. Results: The true PET activity of objects with a size of greater than the full-width at half maximum of the point spread function has been effectively restored in the simulated data. The partial volume correction method is quantitatively comparable to the GTM method. For synthesized FDG–PET with true activity 0 ?ci/cc for cerebrospinal fluid (CSF), 228 ?ci/cc for white matter (WM), and 621 ?ci/cc for gray matter (GM), the method has improved the radioactivity quantification from 186?±?16 ?ci/cc to 30?±?7 ?ci/cc in CSF, 317?±?15 ?ci/cc to 236?±?10 ?ci/cc for WM, 438?±?4 ?ci/cc to 592?±?5 ?ci/cc for GM. Both visual and quantitative assessments show improvement of partial volume correction in the synthesized and phantom experiments. Conclusions: The partial volume correction method improves the quantification of PET images. The method is comparable to the GTM method but does not need MR image segmentation or prior tracer distribution information. The voxel-based method can be particularly useful for combined PET/MRI studies.

Wang, Hesheng; Fei, Baowei

2012-01-01

91

Thermodynamics of aqueous mixtures of nonelectrolytes. 1. Excess volumes of water +. gamma. -butyrolactone mixtures at several temperatures  

SciTech Connect

Excess molar volumes of water + ..gamma..-butyrolactone mixtures were obtained from precise density measurements over the entire mole fraction range and at 10K intervals from 288.15 to 318.15K. Partial molar excess volumes, excess coefficients of thermal expansion, and partial molar excess expansibilities at 298.15K were derived from the results. The significance of these results is discussed in terms of the structural changes in the mixtures.

Abdullah, M.O.; Al-Madafl, S.H.F.; Awwad, A.M.

1987-04-01

92

Densities and Excess Molar Volumes of Binary and Ternary Mixtures of Aqueous Solutions of 2,2,2-Trifluoroethanol with Acetone and Alcohols at the Temperature of 298.15 K and Pressure of 101 kPa  

Microsoft Academic Search

Excess molar volumes VmE of the binary mixtures of (trifluoroethanol + 1-propanol), (trifluoroethanol + 2-propanol), (acetone + water), (methanol + water), (ethanol + water), (1-propanol + water), (2-propanol + water), and the ternary mixtures of (trifluoroethanol + methanol + water), (trifluoroethanol + ethanol + water), (trifluoroethanol~+ 1-propanol + water), (trifluoroethanol + 2-propanol + water) and (trifluoroethanol + acetone + water)

Zadjia Atik

2004-01-01

93

Investigation of partial volume correction methods for brain FDG PET studies  

SciTech Connect

The use of positron emission tomography (PET) in quantitative fluorodeoxyglucose (FDG) studies of aging and dementia has been limited by partial volume effects. A general method for correction of partial volume effects (PVE) in PET involves the following common procedures; segmentation of MRI brain images into gray matter (GM), white matter (WM), cerebral spinal fluid (CSF), and muscle (MS) components; MRI PET registration; and generation of simulated PET images. Afterward, two different approaches can be taken. The first approach derives first a pixel-by-pixel correction map as the ratio of the measured image to the simulated image [with realistic full-width at half-maximum (FWHM)]. The correction map was applied to the MRI segmentation image. Regions of interest (ROI`s) can then be applied to give results free of partial volume effects. The second approach uses the ROI values of the simulated ``pure`` image (with negligible FWHM) and those of the simulated and the measured PET images to correct for the PVE effect. By varying the ratio of radiotracer concentrations for different tissue components, the in-plane FWHM`s of a three-dimensional point spread function, and the ROI size, the authors evaluated the performance of these two approaches in terms of their accuracy and sensitivity to different simulation configurations. The results showed that both approaches are more robust than the approach developed by Muller-Gartner et al., and the second approach is more accurate and more robust than the first. In conclusion, the authors recommend that the second approach should be used on FDG PET images to correct for partial volume effects and to determine whether an apparent change in GM radiotracer concentration is truly due to metabolic changes.

Yang, J.; Huang, S.C.; Mega, M.; Toga, A.W.; Small, G.W.; Phelps, M.E. [Univ. of California, Los Angeles, CA (United States)] [Univ. of California, Los Angeles, CA (United States); Lin, K.P. [Chung Yuan Christian Univ., Chung-Li (China). Dept. of Electrical Engineering] [Chung Yuan Christian Univ., Chung-Li (China). Dept. of Electrical Engineering

1996-12-01

94

Gas solubilities, vapor-liquid equilibria, and partial molal volumes in some hydrogen-hydrocarbon systems  

SciTech Connect

Gas solubilities were measured for hydrogen in n-pentane, 2,3-dimethylbutane, cyclohexane, n-decane, m-xylene, 1,4-diethylbenzene, and 1-methylnaphthalene. Vapor-liquid equilibrium ratios (K's) were measured for the second, third, fifth, and sixth of these systems. Partial molal volumes of hydrogen dissolved in the liquid hydrocarbons were measured for all systems except methylnaphthalene. Temperatures and pressures fell in the ranges 35-320/sup 0/C and 200-2400 psi.

Connolly, J.F.; Kandalic, G.A.

1986-10-01

95

Relationship Between Partial Gastric Volumes and Dyspeptic Symptoms in Fundoplication Patients: A 3D Ultrasonographic Study  

Microsoft Academic Search

OBJECTIVES:Impaired gastric accommodation may induce dyspeptic symptoms in postfundoplication patients. Our aim was to assess the effect of a meal on total and partial gastric volumes in relation to dyspeptic symptoms in both dyspeptic and nondyspeptic fundoplication patients using three-dimensional (3D) ultrasonography.METHODS:Eighteen postfundoplication patients of whom eight with and ten without dyspeptic symptoms and eighteen controls were studied. Three-dimensional ultrasonographic

R. C. H. Scheffer; H. G. Gooszen; E. B. Wassenaar; M. Samsom

2004-01-01

96

Interface profile studies in immiscible and partially miscible binary polymer blends from free volume measurement  

NASA Astrophysics Data System (ADS)

The diffused interface widths in an immiscible and a partially miscible polymer blend namely Polyvinyl chloride/Ethylene vinyl acetate (PVC/EVA) and Polystyrene/Polymethylmethacrylate (PS/PMMA) are experimentally measured and reported here. A new empirical relation found between hydrodynamic interaction parameter ? derived from free volume data and the Flory-Huggins interaction parameter ? is used to construct density profile across the interface to derive the interface width in above two binary blends.

Ramya, P.; Meghala, D.; Pasang, T.; Raj, J. M.; Ranganathaiah, C.; Williams, J. F.

2013-06-01

97

A recovery coefficient method for partial volume correction of PET images  

Microsoft Academic Search

Objectives  Correction of the “partial volume effect” has been an area of great interest in the recent times in quantitative PET imaging\\u000a and has been mainly studied with count recovery models based upon phantoms that incorporate hot spheres in a cold background.\\u000a The goal of this research study was to establish a similar model that is closer to a biological imaging

Shyam M. Srinivas; Thiruvenkatasamy Dhurairaj; Sandip Basu; Gonca Bural; Suleman Surti; Abass Alavi

2009-01-01

98

Excess molar volumes and enthalpies of binary mixtures of an alkanol or an alkane with butyl-vinyl ether or iso-butyl-vinyl ether at 313.15 K  

Microsoft Academic Search

Experimental results are reported of excess molar volumes VmE and excess molar enthalpies HmE at T=313.15K for twelve binary mixtures of alkanols (ethanol, 1-butanol or iso-butanol) or alkanes (n-heptane, iso-octane (2,2,4-trimethylpentane) or n-octane) with butyl-vinyl ether or iso-butyl-vinyl ether. A vibrating-tube densitometer was used to determine VmE. The quantity HmE was measured using a quasi-isothermal flow calorimeter. The applicability of

E. N Rezanova; R. N Lichtenthaler

2001-01-01

99

Target Volume Delineation for Partial Breast Radiotherapy Planning: Clinical Characteristics Associated with Low Interobserver Concordance  

SciTech Connect

Purpose: To examine variability in target volume delineation for partial breast radiotherapy planning and evaluate characteristics associated with low interobserver concordance. Methods and Materials: Thirty patients who underwent planning CT for adjuvant breast radiotherapy formed the study cohort. Using a standardized scale to score seroma clarity and consensus contouring guidelines, three radiation oncologists independently graded seroma clarity and delineated seroma volumes for each case. Seroma geometric center coordinates, maximum diameters in three axes, and volumes were recorded. Conformity index (CI), the ratio of overlapping volume and encompassing delineated volume, was calculated for each case. Cases with CI {<=}0.50 were analyzed to identify features associated with low concordance. Results: The median time from surgery to CT was 42.5 days. For geometric center coordinates, variations from the mean were 0.5-1.1 mm and standard deviations (SDs) were 0.5-1.8 mm. For maximum seroma dimensions, variations from the mean and SDs were predominantly <5 mm, with the largest SDs observed in the medial-lateral axis. The mean CI was 0.61 (range, 0.27-0.84). Five cases had CI {<=}0.50. Conformity index was significantly associated with seroma clarity (p < 0.001) and seroma volume (p < 0.002). Features associated with reduced concordance included tissue stranding from the surgical cavity, proximity to muscle, dense breast parenchyma, and benign calcifications that may be mistaken for surgical clips. Conclusion: Variability in seroma contouring occurred in three dimensions, with the largest variations in the medial-lateral axis. Awareness of clinical features associated with reduced concordance may be applied toward training staff and refining contouring guidelines for partial breast radiotherapy trials.

Petersen, Ross P. [Radiation Therapy Program, British Columbia Cancer Agency, Vancouver Island Centre and University of British Columbia, Victoria, BC (Canada); Truong, Pauline T. [Radiation Therapy Program, British Columbia Cancer Agency, Vancouver Island Centre and University of British Columbia, Victoria, BC (Canada)], E-mail: ptruong@bccancer.bc.ca; Kader, Hosam A.; Berthelet, Eric; Lee, Junella C. [Radiation Therapy Program, British Columbia Cancer Agency, Vancouver Island Centre and University of British Columbia, Victoria, BC (Canada); Hilts, Michelle L. [Radiation Therapy Program, British Columbia Cancer Agency, Vancouver Island Centre and University of Victoria, Victoria, BC (Canada); Kader, Adam S. [Radiation Therapy Program, British Columbia Cancer Agency, Vancouver Island Centre and University of British Columbia, Victoria, BC (Canada); Beckham, Wayne A. [Radiation Therapy Program, British Columbia Cancer Agency, Vancouver Island Centre and University of Victoria, Victoria, BC (Canada); Olivotto, Ivo A. [Radiation Therapy Program, British Columbia Cancer Agency, Vancouver Island Centre and University of British Columbia, Victoria, BC (Canada)

2007-09-01

100

Attachment Levels and Crevicular Depths at the Distal of Mandibular Second Molars Following Removal of Adjacent Third Molars.  

National Technical Information Service (NTIS)

The effect of root planing and curettage on the crevicular depth and periodontal attachment at the distal of mandibular second molars following removal of adjacent impacted or partially erupted third molars was evaluated in eighteen patients between the a...

W. H. Osborne A. J. Snyder T. R. Tempel

1981-01-01

101

A Partial Volume Effect Correction Tailored for 18F-FDG-PET Oncological Studies  

PubMed Central

We have developed, optimized, and validated a method for partial volume effect (PVE) correction of oncological lesions in positron emission tomography (PET) clinical studies, based on recovery coefficients (RC) and on PET measurements of lesion-to-background ratio (L/Bm) and of lesion metabolic volume. An operator-independent technique, based on an optimised threshold of the maximum lesion uptake, allows to define an isocontour around the lesion on PET images in order to measure both lesion radioactivity uptake and lesion metabolic volume. RC are experimentally derived from PET measurements of hot spheres in hot background, miming oncological lesions. RC were obtained as a function of PET measured sphere-to-background ratio and PET measured sphere metabolic volume, both resulting from the threshold-isocontour technique. PVE correction of lesions of a diameter ranging from 10?mm to 40?mm and for measured L/Bm from 2 to 30 was performed using measured RC curves tailored at answering the need to quantify a large variety of real oncological lesions by means of PET. Validation of the PVE correction method resulted to be accurate (>89%) in clinical realistic conditions for lesion diameter > 1?cm, recovering >76% of radioactivity for lesion diameter < 1?cm. Results from patient studies showed that the proposed PVE correction method is suitable and feasible and has an impact on a clinical environment.

Gallivanone, F.; Canevari, C.; Gianolli, L.; Salvatore, C.; Della Rosa, P. A.; Gilardi, M. C.; Castiglioni, I.

2013-01-01

102

Excess molar volumes and dynamic viscosities for binary mixtures of toluene + n-alkanes (C 5–C 10) at T = 298.15 K – Comparison with Prigogine–Flory–Patterson theory  

Microsoft Academic Search

Densities ?, dynamic viscosities ?, for binary mixtures of toluene with some n-alkanes, namely, n-pentane, n-hexane, n-heptane, n-octane, n-nonane, and n-decane have been measured over the complete composition range. Excess molar volumes VE, viscosity deviations ??, and excess Gibbs free energy of activation ?G?E, were calculated there from and were correlated by Redlich–Kister type function in terms of mole fractions.

Hossein Iloukhani; Mahdi Rezaei-Sameti; Jalal Basiri-Parsa

2006-01-01

103

Excess molar volumes of binary mixtures of aliphatic alcohols (C 1–C 5) with Nitromethane over the temperature range 293.15 to 308.15 K: Application of the ERAS model and cubic EOS  

Microsoft Academic Search

Densities were measured for the binary mixtures of methanol, ethanol, 1-propanol, 1-butanol with nitromethane at temperatures (293.15, 298.15, 303.15 and 308.15) K and for 1-pentanol with nitromethane at temperatures (303.15 and 308.15) K and atmospheric pressure. Densities were determined using a vibrating-tube densimeter. Excess molar volumes as a function of mole fraction were derived, and the computed results were fitted

M. Almasi; L. Mousavi

2011-01-01

104

Experimental determination and modelling of densities and excess molar volumes of ternary system (1-butanol + cyclohexylamine + n-heptane) and corresponding binaries from 288.15 to 323.15 K  

Microsoft Academic Search

Experimental densities ? and excess molar volumes VE of one ternary and three binary systems containing 1-butanol, cyclohexylamine and n-heptane at temperatures from 283.15 to 323.15K are reported. Density measurements were performed by an Anton Paar DMA 5000 vibrating tube densimeter. The obtained VE of binary systems were fitted to the Redlich–Kister equation, and to the Nagata–Tamura equation for the

Mirjana Lj. Kijev?anin; Ivona R. Radovi?; Slobodan P. Šerbanovi?; Aleksandar Ž. Tasi?; Bojan D. Djordjevi?

2009-01-01

105

Excess molar volume, viscosity, and refractive index study for the ternary mixture {2-methyl-2-butanol (1) + tetrahydrofuran (2) + propylamine (3)} at different temperatures. Application of the ERAS-model and Peng–Robinson–Stryjek–Vera equation of state  

Microsoft Academic Search

Densities, viscosities, and refractive indices of the ternary mixture consist of {2-methyl-2-butanol (1)+tetrahydrofuran (THF) (2)+propylamine (3)} at a temperature of 298.15K and related binary mixtures were measured at temperatures of (288.15, 298.15, and 308.15)K at ambient pressure. Data were used to calculate the excess molar volumes and the deviations of the viscosity and refractive index. The Redlich–Kister and the Cibulka

M. Fattahi; H. Iloukhani

2010-01-01

106

The molar volume of cubic garnets in the system SiO2-Al2O3-TiO2-Fe2O3-Cr2O3-FeO-MnO-MgO-CaO-Na2O  

NASA Astrophysics Data System (ADS)

Garnet is a critical phase that controls major and trace element partitioning at pressures above ~3 GPa during partial melting of the Earth's upper mantle. A molar volume model is calibrated for cubic garnets (space group Ia3d) in the oxide system listed in the title. This model and a recent calibration of spinel molar volume (Hamecher et al., in press, CMP) will be used in calibration of thermodynamic activity-composition models of garnet and pyroxene solid solutions. The activity and molar volume models will be incorporated into the next generation MELTS (Ghiorso & Sack, 1995, CMP) model, xMELTS. A new garnet volume model calibrated with recent in situ high-P, T diffraction data is crucial for accurately modeling key mineralogical transitions in the mantle, e.g., the spinel-garnet transition and the mantle transition zone. Above 5 GPa a majorite component is an essential part of any thermodynamic model of mantle garnets, which to be useful must accurately predict garnet stability with respect to spinel, pyroxene, perovskites, and melt. Our model system contains nine independent end members: Ca3Al2Si3O12, Mg3Al2Si3O12, Fe2+3Al2Si3O12, Mg3Cr2Si3O12, Mg3Fe3+2Si3O12, Mn3Al2Si3O12, Na2(MgSi2)Si3O12, Mg3(TiMg)Si3O12, and cubic majorite component Mg3(MgSi)Si3O12. An inclusive set of end-member components is formed by linear combinations of these explicit end members. Approximately 950 published X-ray diffraction experiments performed on garnets at ambient and in situ high-P, T conditions are used to calibrate end-member equations of state and an excess volume model for this system. Optimal values of the bulk modulus and its pressure derivative are obtained by analyzing published compression and/or ultrasonic data for the end members for which such studies exist; for other end members, density functional theory results are used. For any cubic garnet in this chemical system, the model molar volume is obtained by adding excess volume terms to a linear combination of the nine independent end-member volumes. In the first step of our least squares fitting procedure we calculate volumes of the explicit end members as a function of P and T using the high-T Vinet equation of state. We allow standard state volumes and coefficients of thermal expansion to vary for those independent end members where pure compositional data exist, either for the phase itself or for an appropriate dependent end member. For each dependent end member for which there are data, we calculate the volume of reaction for formation of the phase from the independent end members, ?V. We then fit the binary and mixed composition data, using the singular value analysis method of Lawson & Hanson (1974) to ensure that the calibrated combinations of excess parameters obey the nine ?V constraints from the first step. A key plausibility check on the model results from comparing the predicted T-dependence of the bulk modulus to high-T ultrasonic results that were not used in the calibration. The calculated pressure of the spinel-garnet transition using the new volume models is compared to that obtained with the previous models. The implications our model has for the density of the lithospheric mantle are explored.

Hamecher, E. A.; Antoshechkina, P. M.; Ghiorso, M. S.; Asimow, P. D.

2012-12-01

107

Increased Skeletal Muscle Volume in Women With Familial Partial Lipodystrophy, Dunnigan Variety  

PubMed Central

Introduction: Familial partial lipodystrophy, Dunnigan variety (FPLD), an autosomal dominant disorder caused by LMNA mutations, is characterized by fat loss from the extremities. However, it is unclear whether these patients appear muscular because of a lack of subcutaneous fat or have an actual increase in muscle mass. Therefore, we compared muscle mass and volume of selected muscles in women with FPLD and control subjects using dual-emission x-ray absorptiometry (DXA) and magnetic resonance imaging (MRI). Methods: Whole-body axial MRI and DXA scans were obtained on 39 women, aged 18 to 65 years, with FPLD and 17 healthy women matched for body mass index and age (group 1). Volumes of muscles in both the thighs, calves, and psoas were calculated from MRI scans and muscle mass in extremities were calculated from DXA. In addition, abdominal MRI and DXA scans were analyzed from 129 healthy, frequency-matched women (group 2). Comparisons between women with FPLD and control subjects were made using ANOVA, adjusting for height, body mass index, and age. Results: Patients with FPLD, compared with control subjects had significantly greater volumes of the thigh muscles, (6358 ± 1491 vs 5198 ± 716 mL, P = .002), calf muscles (3133 ± 713 vs 2397 ± 335 mL; P < .001), and psoas muscles (210 ± 51 vs 175 ± 34 [group 1] and 165 ± 38 mL [group 2], P < .001). Patients with FPLD also had significantly increased arm and leg muscle masses when measured by DXA (P < .001). Insulin sensitivity, assessed by insulin tolerance tests, was negatively correlated to the calf muscle volume. Conclusions: Female patients with FPLD have increased skeletal muscle volume and mass compared with those of normal women.

Ji, Hongzhao; Weatherall, Paul; Adams-Huet, Beverley

2013-01-01

108

Comparison of Partial Volume Effects in Arterial and Venous Contrast Curves in CT Brain Perfusion Imaging  

PubMed Central

Purpose In brain CT perfusion (CTP), the arterial contrast bolus is scaled to have the same area under the curve (AUC) as the venous outflow to correct for partial volume effects (PVE). This scaling is based on the assumption that large veins are unaffected by PVE. Measurement of the internal carotid artery (ICA), usually unaffected by PVE due to its large diameter, may avoid the need for partial volume correction. The aims of this work are to examine i) the assumptions behind PVE correction and ii) the potential of selecting the ICA obviating correction for PVE. Methods The AUC of the ICA and sagittal sinus were measured in CTP datasets from 52 patients. The AUCs were determined by i) using commercial CTP software based on a Gaussian curve-fitting to the time attenuation curve, and ii) by simple integration of the time attenuation curve over a time interval. In addition, frames acquired up to 3 minutes after first bolus passage were used to examine the ratio of arterial and venous enhancement. The impact of selecting the ICA without PVE correction was illustrated by reporting cerebral blood volume (CBV) measurements. Results In 49 of 52 patients, the AUC of the ICA was significantly larger than that of the sagittal sinus (p?=?0.017). Measured after the first pass bolus, contrast enhancement remained 50% higher in the ICA just after the first pass bolus, and 30% higher 3 minutes later. CBV measurements were significantly lowered when the ICA was used without PVE correction. Conclusions Contradicting the assumptions underlying PVE correction, contrast in the ICA was significantly higher than in the sagittal sinus, even 3 minutes after the first pass of the contrast bolus. PVE correction might lead to overestimation of CBV if the CBV is calculated using the AUC of the time attenuation curves.

Riordan, Alan J.; Bennink, Edwin; Dankbaar, Jan Willem; Viergever, Max A.; Velthuis, Birgitta K.; Smit, Ewoud J.; de Jong, Hugo W. A. M.

2014-01-01

109

Overcoming Nonlinear Partial Volume Effects in Known-Component Reconstruction of Cochlear Implants  

PubMed Central

Nonlinear partial volume (NLPV) effects can be significant for objects with large attenuation differences and fine detail structures near the spatial resolution limits of a tomographic system. This is particularly true for small metal devices like cochlear implants. While traditional model-based approaches might alleviate these artifacts through very fine sampling of the image volume and subsampling of rays to each detector element, such solutions can be extremely burdensome in terms of memory and computational requirements. The work presented in this paper leverages the model-based approach called “known-component reconstruction” (KCR) where prior knowledge of a surgical device is integrated into the estimation. In KCR, the parameterization of the object separates the volume into an unknown background anatomy and a known component with unknown registration. Thus, one can model projections of an implant at very high spatial resolution while limiting the spatial resolution of the anatomy - in effect, modeling NLPV effects where they are most significant. We present modifications of the KCR approach that can be used to largely eliminate NLPV artifacts, and demonstrate the efficacy of the modified technique (with improved image quality and accurate implant position estimates) for the cochlear implant imaging scenario.

Stayman, J. W.; Dang, H.; Otake, Y.; Zbijewski, W.; Noble, J.; Dawant, B.; Labadie, R.; Carey, J. P.; Siewerdsen, J. H.

2013-01-01

110

Dedicated breast computed tomography: Volume image denoising via a partial-diffusion equation based technique  

PubMed Central

Dedicated breast computed tomography (CT) imaging possesses the potential for improved lesion detection over conventional mammograms, especially for women with dense breasts. The breast CT images are acquired with a glandular dose comparable to that of standard two-view mammography for a single breast. Due to dose constraints, the reconstructed volume has a non-negligible quantum noise when thin section CT slices are visualized. It is thus desirable to reduce noise in the reconstructed breast volume without loss of spatial resolution. In this study, partial diffusion equation (PDE) based denoising techniques specifically for breast CT were applied at different steps along the reconstruction process and it was found that denoising performed better when applied to the projection data rather than reconstructed data. Simulation results from the contrast detail phantom show that the PDE technique outperforms Wiener denoising as well as adaptive trimmed mean filter. The PDE technique increases its performance advantage relative to Wiener techniques when the photon fluence is reduced. With the PDE technique, the sensitivity for lesion detection using the contrast detail phantom drops by less than 7% when the dose is cut down to 40% of the two-view mammography. For subjective evaluation, the PDE technique was applied to two human subject breast data sets acquired on a prototype breast CT system. The denoised images had appealing visual characteristics with much lower noise levels and improved tissue textures while maintaining sharpness of the original reconstructed volume.

Xia, Jessie Q.; Lo, Joseph Y.; Yang, Kai; Floyd, Carey E.; Boone, John M.

2008-01-01

111

Partial volume effect of cingulum tract in diffusion-tensor MRI  

NASA Astrophysics Data System (ADS)

Diffusion tensor imaging (DTI) represents a promising tool for the early diagnosis of certain brain diseases. Many DTI studies have compared differences in local diffusivity in specific region-of- interest (ROI) between patient and control groups to find possible disease markers. However, local diffusivity results may be influenced by partial volume effects (PVE), particularly in small white matter tracts that border grey matter tissue. Here, we investigated the influence of PVE on local diffusivity measurements in a small but critical white matter tract, the cingulum. Results demonstrated significant variability in PVE that contribute to local diffusivity in the cingulum. Our results highlight the need for careful consideration of PVE when computing diffusivity of small tissues.

Cao, Ning; Gold, Brian T.; Zhang, Jun

2008-04-01

112

Molar ectopic pregnancy in the uterine cornus.  

PubMed

Cornual pregnancy is a rare form of ectopic pregnancy. The incidence of hydatiform molar pregnancy is 1 in 1000 to 2000 pregnancies. Molar cornual ectopic pregnancy is extremely rare. A 41-year-old nulliparous woman was admitted via the emergency department because of vaginal bleeding for 2 weeks. Transvaginal sonography exhibited a heterogeneous hypoechoic shadow in the endometrium that suggested a hematometra including blood clots and tissue, and a multicystic echogenic mass, with flow at color Doppler ultrasonography, in the lateral wall of the uterus. A laparoscopic cornuostomy was performed. Pathologic analysis demonstrated placental tissue with features consistent with a partial molar pregnancy. Systemic methotrexate therapy was administered to treat the possible remnants of the molar pregnancy. Molar cornual ectopic pregnancy can be successfully treated with laparoscopic cornuostomy and systemic methotrexate therapy. PMID:20226416

Hwang, Jong Ha; Lee, Jae Kwan; Lee, Nak Woo; Lee, Kyu Wan

2010-01-01

113

Volume properties and structure of aqueous solutions of urea at 263–348 K  

Microsoft Academic Search

The apparent molar volume of urea ? in aqueous solution in the range T = 273–323 K and m = 1–10 (molality) depends linearly on m\\u000a 1\\/2. An equation for ?(m, T) was derived. The partial molar characteristics of urea ?\\u000a 2 and water ?\\u000a 1 (volume, dilatability, and temperature coefficients of volumes) were calculated. The ?(T) dependences have characteristic

V. P. Korolev

2008-01-01

114

Thermodynamics of aqueous amines: excess molar heat capacities, volumes, and expansibilities of {water + methyldiethanolamine (MDEA)} and {water + 2-amino-2-methyl-1-propanol (AMP)}  

Microsoft Academic Search

The heat capacities of aqueous solutions of methyldiethanolamine (MDEA) and 2-amino-2-methyl-1-propanol (AMP) were measured in a heat-flux differential scanning calorimeter at temperatures 278.15K?T? 368.15 K, to yield excess molar heat capacities Cp,mEover the whole mole fraction range. Densities of aqueous AMP were determined with a vibrating tube densimeter over the temperature range 293.15 K?T? 353.15 K, and used to derive

Peter R. Tremaine

2002-01-01

115

An interpretative model for the anomalous behavior of some excess properties in mixed liquid systems: A relationship between excess molar volumes and excess compressibilities in strongly self-aggregated fluids  

NASA Astrophysics Data System (ADS)

A simple theoretical model based on the hole theory of the liquid state has been developed in order to find a relationship between the excess molar volume and the excess compressibility of a two-component fluid. The model has been extended to investigate strongly associating fluids dissolved in an apolar solvent. Such a model nicely explains our recent results obtained from a Brillouin scattering study of the nonideal mixture between tert-butyl alcohol and 2-2' dimethyl butane. Its validity, however, seems to be rather general and it could be usefully applied to rationalize the excess properties of several nonideal binary fluid mixtures.

Raudino, Antonio; Palombo, Francesca; Cataliotti, Rosario Sergio

2008-07-01

116

Temperature Dependence of Densities and Excess Molar Volumes of the Ternary Mixture (1Butanol + Chloroform + Benzene) and its Binary Constituents (1Butanol + Chloroform and 1Butanol + Benzene)  

Microsoft Academic Search

Densities ? of the 1-butanol + chloroform + benzene ternary mixture and the 1-butanol + chloroform and 1-butanol + benzene binaries have\\u000a been measured at six temperatures (288.15, 293.15, 298.15, 303.15, 308.15, and 313.15) K and atmospheric pressure, using an\\u000a oscillating U-tube densimeter. From these densities, excess molar volumes (V\\u000a E) were calculated and fitted to the Redlich–Kister equation for all binary mixtures and to the Nagata and Tamura

Jelena D. Smiljani?; Mirjana Lj. Kijev?anin; Bojan D. Djordjevi?; Dušan K. Grozdani?; Slobodan P. Šerbanovi?

2008-01-01

117

Differences in Effective Target Volume Between Various Techniques of Accelerated Partial Breast Irradiation  

SciTech Connect

Purpose: Different cavity expansions are used to define the clinical target volume (CTV) for accelerated partial breast irradiation (APBI) delivered via balloon brachytherapy (1 cm) vs. three-dimensional conformal radiotherapy (3D-CRT) (1.5 cm). Previous studies have argued that the CTVs generated by these different margins are effectively equivalent. In this study, we use deformable registration to assess the effective CTV treated by balloon brachytherapy on clinically representative 3D-CRT planning images. Methods and Materials: Ten patients previously treated with the MammoSite were studied. Each patient had two computed tomography (CT) scans, one acquired before and one after balloon implantation. In-house deformable registration software was used to deform the MammoSite CTV onto the balloonless CT set. The deformed CTV was validated using anatomical landmarks common to both CT scans. Results: The effective CTV treated by the MammoSite was on average 7% {+-} 10% larger and 38% {+-} 4% smaller than 3D-CRT CTVs created using uniform expansions of 1 and 1.5 cm, respectively. The average effective CTV margin was 1.0 cm, the same as the actual MammoSite CTV margin. However, the effective CTV margin was nonuniform and could range from 5 to 15 mm in any given direction. Effective margins <1 cm were attributable to poor cavity-balloon conformance. Balloon size relative to the cavity did not significantly correlate with the effective margin. Conclusion: In this study, the 1.0-cm MammoSite CTV margin treated an effective volume that was significantly smaller than the 3D-CRT CTV based on a 1.5-cm margin.

Shaitelman, Simona F.; Vicini, Frank A.; Grills, Inga S.; Martinez, Alvaro A.; Yan Di [Department of Radiation Oncology, William Beaumont Hospital, Royal Oak, MI (United States); Kim, Leonard H., E-mail: lkim@beaumonthospitals.com [Department of Radiation Oncology, William Beaumont Hospital, Royal Oak, MI (United States)

2012-01-01

118

Prone accelerated partial breast irradiation after breast-conserving surgery: Preliminary clinical results and dose–volume histogram analysis  

Microsoft Academic Search

PurposeTo report the clinical and dose–volume histogram results of the first 47 patients accrued to a protocol of accelerated partial breast irradiation. Patients were treated in the prone position with three-dimensional conformal radiotherapy after breast-conserving surgery.

Silvia C. Formenti; Minh Tam Truong; Judith D. Goldberg; Vandana Mukhi; Barry Rosenstein; Daniel Roses; Richard Shapiro; Amber Guth; J. Keith Dewyngaert

2004-01-01

119

Comparative assessment of statistical brain MR image segmentation algorithms and their impact on partial volume correction in PET  

Microsoft Academic Search

Magnetic resonance imaging (MRI)-guided partial volume effect correction (PVC) in brain positron emission tomography (PET) is now a well-established approach to compensate the large bias in the estimate of regional radioactivity concentration, especially for small structures. The accuracy of the algorithms developed so far is, however, largely dependent on the performance of segmentation methods partitioning MRI brain data into its

Habib Zaidi; Torsten Ruest; Frederic Schoenahl; Marie-Louise Montandon

2006-01-01

120

Application of generalized partial volume estimation for mutual information based registration of high resolution SAR and optical imagery  

Microsoft Academic Search

Mutual information (MI) has proven its effectiveness for automated multimodal image registration for numerous remote sensing applications like image fusion. We analyze MI performance with respect to joint histogram bin size and the employed joint histogramming technique. The affect of generalized partial volume estimation (GPVE) utilizing B-spline kernels with different histogram bin sizes on MI performance has been thoroughly explored

Sahil Suri; Peter Reinartz

2008-01-01

121

Spinal Cord Tolerance to Single-Fraction Partial-Volume Irradiation: A Swine Model  

SciTech Connect

Purpose: To determine the spinal cord tolerance to single-fraction, partial-volume irradiation in swine. Methods and Materials: A 5-cm-long cervical segment was irradiated in 38-47-week-old Yucatan minipigs using a dedicated, image-guided radiosurgery linear accelerator. The radiation was delivered to a cylindrical volume approximately 5 cm in length and 2 cm in diameter that was positioned lateral to the cervical spinal cord, resulting in a dose distribution with the 90%, 50%, and 10% isodose lines traversing the ipsilateral, central, and contralateral spinal cord, respectively. The dose was prescribed to the 90% isodose line. A total of 26 pigs were stratified into eight dose groups of 12-47 Gy. The mean maximum spinal cord dose was 16.9 {+-} 0.1, 18.9 {+-} 0.1, 21.0 {+-} 0.1, 23.0 {+-} 0.2, and 25.3 {+-} 0.3 Gy in the 16-, 18-, 20-, 22-, and 24-Gy dose groups, respectively. The mean percentage of spinal cord volumes receiving {>=}10 Gy for the same groups were 43% {+-} 3%, 48% {+-} 4%, 51% {+-} 2%, 57% {+-} 2%, and 59% {+-} 4%. The study endpoint was motor neurologic deficit determined by a change in gait during a 1-year follow-up period. Results: A steep dose-response curve was observed with a median effective dose for the maximum dose point of 20.0 Gy (95% confidence interval, 18.3-21.7). Excellent agreement was observed between the occurrence of neurologic change and the presence of histologic change. All the minipigs with motor deficits showed some degree of demyelination and focal white matter necrosis on the irradiated side, with relative sparing of the gray matter. The histologic findings were unremarkable in the minipigs with normal neurologic status. Conclusions: Our results have indicated that for a dose distribution with a steep lateral gradient, the pigs had a lower median effective dose for paralysis than has been observed in rats and more closely resembles that for rats, mice, and guinea pigs receiving uniform spinal cord irradiation.

Medin, Paul M., E-mail: Paul.medin@utsouthwestern.ed [Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, TX (United States); Foster, Ryan D. [Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, TX (United States); Kogel, Albert J. van der [Department of Radiation Oncology, Radboud University Medical Center Nijmegen, Nijmegen (Netherlands); Sayre, James W. [Department of Biostatistics, University of California, Los Angeles, School of Medicine, Los Angeles, CA (United States); Department of Radiology, University of California, Los Angeles, School of Medicine, Los Angeles, CA (United States); McBride, William H. [Department of Radiation Oncology, University of California, Los Angeles, School of Medicine, Los Angeles, CA (United States); Solberg, Timothy D. [Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, TX (United States)

2011-01-01

122

Isotropic non-white matter partial volume effects in constrained spherical deconvolution.  

PubMed

Diffusion-weighted (DW) magnetic resonance imaging (MRI) is a non-invasive imaging method, which can be used to investigate neural tracts in the white matter (WM) of the brain. Significant partial volume effects (PVEs) are present in the DW signal due to relatively large voxel sizes. These PVEs can be caused by both non-WM tissue, such as gray matter (GM) and cerebrospinal fluid (CSF), and by multiple non-parallel WM fiber populations. High angular resolution diffusion imaging (HARDI) methods have been developed to correctly characterize complex WM fiber configurations, but to date, many of the HARDI methods do not account for non-WM PVEs. In this work, we investigated the isotropic PVEs caused by non-WM tissue in WM voxels on fiber orientations extracted with constrained spherical deconvolution (CSD). Experiments were performed on simulated and real DW-MRI data. In particular, simulations were performed to demonstrate the effects of varying the diffusion weightings, signal-to-noise ratios (SNRs), fiber configurations, and tissue fractions. Our results show that the presence of non-WM tissue signal causes a decrease in the precision of the detected fiber orientations and an increase in the detection of false peaks in CSD. We estimated 35-50% of WM voxels to be affected by non-WM PVEs. For HARDI sequences, which typically have a relatively high degree of diffusion weighting, these adverse effects are most pronounced in voxels with GM PVEs. The non-WM PVEs become severe with 50% GM volume for maximum spherical harmonics orders of 8 and below, and already with 25% GM volume for higher orders. In addition, a low diffusion weighting or SNR increases the effects. The non-WM PVEs may cause problems in connectomics, where reliable fiber tracking at the WM-GM interface is especially important. We suggest acquiring data with high diffusion-weighting 2500-3000 s/mm(2), reasonable SNR (~30) and using lower SH orders in GM contaminated regions to minimize the non-WM PVEs in CSD. PMID:24734018

Roine, Timo; Jeurissen, Ben; Perrone, Daniele; Aelterman, Jan; Leemans, Alexander; Philips, Wilfried; Sijbers, Jan

2014-01-01

123

Isotropic non-white matter partial volume effects in constrained spherical deconvolution  

PubMed Central

Diffusion-weighted (DW) magnetic resonance imaging (MRI) is a non-invasive imaging method, which can be used to investigate neural tracts in the white matter (WM) of the brain. Significant partial volume effects (PVEs) are present in the DW signal due to relatively large voxel sizes. These PVEs can be caused by both non-WM tissue, such as gray matter (GM) and cerebrospinal fluid (CSF), and by multiple non-parallel WM fiber populations. High angular resolution diffusion imaging (HARDI) methods have been developed to correctly characterize complex WM fiber configurations, but to date, many of the HARDI methods do not account for non-WM PVEs. In this work, we investigated the isotropic PVEs caused by non-WM tissue in WM voxels on fiber orientations extracted with constrained spherical deconvolution (CSD). Experiments were performed on simulated and real DW-MRI data. In particular, simulations were performed to demonstrate the effects of varying the diffusion weightings, signal-to-noise ratios (SNRs), fiber configurations, and tissue fractions. Our results show that the presence of non-WM tissue signal causes a decrease in the precision of the detected fiber orientations and an increase in the detection of false peaks in CSD. We estimated 35–50% of WM voxels to be affected by non-WM PVEs. For HARDI sequences, which typically have a relatively high degree of diffusion weighting, these adverse effects are most pronounced in voxels with GM PVEs. The non-WM PVEs become severe with 50% GM volume for maximum spherical harmonics orders of 8 and below, and already with 25% GM volume for higher orders. In addition, a low diffusion weighting or SNR increases the effects. The non-WM PVEs may cause problems in connectomics, where reliable fiber tracking at the WM–GM interface is especially important. We suggest acquiring data with high diffusion-weighting 2500–3000 s/mm2, reasonable SNR (~30) and using lower SH orders in GM contaminated regions to minimize the non-WM PVEs in CSD.

Roine, Timo; Jeurissen, Ben; Perrone, Daniele; Aelterman, Jan; Leemans, Alexander; Philips, Wilfried; Sijbers, Jan

2014-01-01

124

Two methods to generate templates for template-based partial volume effect correction: SPECT phantom experiments  

NASA Astrophysics Data System (ADS)

In this paper, we explore the applicability of template-based compensation for the partial volume effect (PVE) for situations where (i) the image has multiple uptake sites (tumors and organs) but only one of them is treated as a region of interest (ROI) with the boundaries available from a high-resolution modality and (ii) no information regarding activities inside or outside this ROI is a priori available. We modeled this situation by performing SPECT acquisitions of phantoms containing 21 containers, which had different shapes and sizes and were filled with different levels of activity. In our analysis, each of these containers was treated as an individual ROI. We compared the performance of two methods of template construction. In method 1, the ROI template value was obtained from a conventionally reconstructed (without PVEC) image. In method 2, the ROI template value was directly (bypassing the PVE-affected conventional image) calculated from projections using region-based reconstruction. Our processing shows that method 1 resulted in consistent (activities for all 21 ROIs were improved) but relatively weak PVE compensation (errors of recovered total activities were equal to or lower than 10% for 5 ROIs only). Application of method 2 resulted in a selective (activities for 19 ROIs were improved) but considerably better compensation when compared to method 1 (errors of recovered total activities were equal to or lower than 10% for 10 ROIs).

Shcherbinin, S.; Grimes, J.; Celler, A.

2013-02-01

125

Partial volume effect estimation and correction in the aortic vascular wall in PET imaging.  

PubMed

We evaluated the impact of partial volume effect (PVE) in the assessment of arterial diseases with (18)FDG PET. An anthropomorphic digital phantom enabling the modeling of aorta related diseases like atherosclerosis and arteritis was used. Based on this phantom, we performed GATE Monte Carlo simulations to produce realistic PET images with a known organ segmentation and ground truth activity values. Images corresponding to 15 different activity-concentration ratios between the aortic wall and the blood and to 7 different wall thicknesses were generated. Using the PET images, we compared the theoretical wall-to-blood activity-concentration ratios (WBRs) with the measured WBRs obtained with five measurement methods: (1) measurement made by a physician (Expert), (2) automated measurement supposed to mimic the physician measurements (Max), (3) simple correction based on a recovery coefficient (Max-RC), (4) measurement based on an ideal VOI segmentation (Mean-VOI) and (5) measurement corrected for PVE using an ideal geometric transfer matrix (GTM) method. We found that Mean-VOI WBRs values were strongly affected by PVE. WBRs obtained by the physician measurement, by the Max method and by the Max-RC method were more accurate than WBRs obtained with the Mean-VOI approach. However Expert, Max and Max-RC WBRs strongly depended on the wall thickness. Only the GTM corrected WBRs did not depend on the wall thickness. Using the GTM method, we obtained more reproducible ratio values that could be compared across wall thickness. Yet, the feasibility of the implementation of a GTM-like method on real data remains to be studied. PMID:24099932

Burg, S; Dupas, A; Stute, S; Dieudonné, A; Huet, P; Le Guludec, D; Buvat, I

2013-11-01

126

Transfer Partial Molar Isentropic Compressibilities of ( l-Alanine/ l-Glutamine/Glycylglycine) from Water to 0.512 {mol} \\cdot {kg}^{-1} Aqueous {KNO}3/0.512 {mol} \\cdot {kg}^{-1} Aqueous {K}2{SO}4 Solutions Between 298.15 K and 323.15 K  

NASA Astrophysics Data System (ADS)

Speeds of sound of ( l-alanine/ l-glutamine/glycylglycine + 0.512 {mol}\\cdot {kg}^{-1} aqueous {KNO}3/0.512 {mol}\\cdot {kg}^{-1} aqueous {K}2{SO}4) systems have been measured for several molal concentrations of amino acid/peptide at different temperatures: T = (298.15 to 323.15) K. Using the speed-of-sound and density data, the parameters, partial molar isentropic compressibilities ? _{kappa }0 and transfer partial molar isentropic compressibilities ? _{tr} ? _{kappa }0, have been computed. The trends of variation of ? _{kappa }0 and ? _{tr} ? _{kappa }0 with changes in molal concentration of the solute and temperature have been discussed in terms of zwitterion-ion, zwitterion-water dipole, ion-water dipole, and ion-ion interactions operative in the systems.

Riyazuddeen; Gazal, Umaima

2013-03-01

127

Investigation of two-dimensional channel flow with a partially compliant wall using finite volume-finite difference approach  

Microsoft Academic Search

This paper presents a numerical simulation of steady two-dimensional channel flow with a partially compliant wall. Navier-Stokes equation is solved using an unstructured finite volume method (FVM). The deformation of the compliant wall is determined by solving a membrane equation using finite difference method (FDM). The membrane equation and Navier-Stokes equation are coupled iteratively to determine the shape of the

X. Zhang; R. Ajaykumar; N. M. Sudharsan; K. Kumar

2005-01-01

128

Partial volume correction of PET-imaged tumor heterogeneity using expectation maximization with a spatially varying point spread function  

PubMed Central

Tumor heterogeneities observed in positron emission tomography (PET) imaging are frequently compromised of partial volume effects which may affect treatment prognosis, assessment, or future implementations such as biologically optimized treatment planning (dose painting). This paper presents a method for partial volume correction of PET-imaged heterogeneous tumors. A point source was scanned on a GE Discover LS at positions of increasing radii from the scanner’s center to obtain the spatially varying point spread function (PSF). PSF images were fit in three dimensions to Gaussian distributions using least squares optimization. Continuous expressions were devised for each Gaussian width as a function of radial distance, allowing for generation of the system PSF at any position in space. A spatially varying partial volume correction (SV-PVC) technique was developed using expectation maximization (EM) and a stopping criterion based on the method’s correction matrix generated for each iteration. The SV-PVC was validated using a standard tumor phantom and a tumor heterogeneity phantom, and was applied to a heterogeneous patient tumor. SV-PVC results were compared to results obtained from spatially invariant partial volume correction (SINV-PVC), which used directionally uniform three dimensional kernels. SV-PVC of the standard tumor phantom increased the maximum observed sphere activity by 55 and 40% for 10 and 13 mm diameter spheres, respectively. Tumor heterogeneity phantom results demonstrated that as net changes in the EM correction matrix decreased below 35%, further iterations improved overall quantitative accuracy by less than 1%. SV-PVC of clinically observed tumors frequently exhibited changes of ±30% in regions of heterogeneity. The SV-PVC method implemented spatially varying kernel widths and automatically determined the number of iterations for optimal restoration, parameters which are arbitrarily chosen in SINV-PVC. Comparing SV-PVC to SINV-PVC demonstrated that similar results could be reached using both methods, but large differences result for the arbitrary selection of SINV-PVC parameters. The presented SV-PVC method was performed without user intervention, requiring only a tumor mask as input. Research involving PET-imaged tumor heterogeneity should include correcting for partial volume effects to improve the quantitative accuracy of results.

Barbee, David L; Flynn, Ryan T; Holden, James E; Nickles, Robert J; Jeraj, Robert

2010-01-01

129

Densities, Apparent Molar Volumes and Viscosities of Concentrated Aqueous NaNO 3 Solutions at Temperatures from 298 to 607 K and at Pressures up to 30 MPa  

Microsoft Academic Search

Densities of four (2.124, 2.953, 5.015 and 6.271 mol-kg?1) and viscosities of eight (0.265, 0.503, 0.665, 1.412, 2.106, 2.977, 5.015 and 6.271 mol-kg?1) NaNO3(aq) solutions have been measured with a constant-volume piezometer immersed in a precision liquid thermostat and using capillary flow techniques, respectively. Measurements were made at pressures up to 30 MPa. The temperature range was 298–607 K for

Ilmutdin M. Abdulagatov; Nazim D. Azizov

2005-01-01

130

Innovative Materials Development and Testing. Volume 5. Partial Depth Spall Repair in Jointed Concrete Pavements.  

National Technical Information Service (NTIS)

The partial-depth spall-repair experiments, conducted as part of the Strategic Highway Research Program (SHRP) H-106 project, is one of the most extensive attempts to date to evaluate the performance of various rapid-setting materials and procedures used ...

C. A. G. Mojab A. J. Patel A. R. Romine

1993-01-01

131

The impact of retained third molars on the deployed airman.  

PubMed

Dental emergencies can significantly affect the mission of the deployed unit. As many as 22% of all emergency department visits at a deployed Expeditionary Medical Support facility can be attributed to dental problems and many of these problems are caused by impacted third molar teeth. Currently, there is no reliable method of predicting when asymptomatic, partially erupted third molar teeth will become painful. Therefore, it is imperative that Air Force dental providers carefully consider the consequences of giving patients a clean bill of health when asymptomatic, partially erupted third molar teeth are present in the oral cavity. Recommendations for future study are presented. PMID:18277719

Langsten, Robert E; Dunn, William J

2008-01-01

132

Partial volume tissue classification of multichannel magnetic resonance images-a mixel model  

Microsoft Academic Search

A single volume element (voxel) in a medical image may be composed of a mixture of multiple tissue types. The authors call voxels which contain multiple tissue classes mixels. A statistical mixel image model based on Markov random field (MRF) theory and an algorithm for the classification of mixels are presented. The authors concentrate on the classification of multichannel magnetic

Hwan SOO Choi; David R. Haynor; Yongmin Kim

1991-01-01

133

VAPOR PRESSURES, LIQUID MOLAR VOLUMES, VAPOR NON-IDEALITIES, AND CRITICAL PROPERTIES OF SOME FLUORINATED ETHERS: CF3OCF2OCF3, CF3OCF2CF2H, C-CF2CF2CF2O, CF3OCF2H, AND CF3OCH3; AND OF CCL3F AND CF2CLH  

EPA Science Inventory

The paper reports results of measurements of vapor pressures, compressibilities, expansivities, and molar volumes of the liquid phase between room temperature and the critical temperature for a series of fluorinated ethers: CF3OCF2-OCF3, CF3OCF2CF2H, c- CF2CF2CF2O, CF3OCF2H, and ...

134

Improvement of partial volume segmentation for brain tissue on diffusion tensor images using multiple-tensor estimation.  

PubMed

To improve evaluations of cortical and subcortical diffusivity in neurological diseases, it is necessary to improve the accuracy of brain diffusion tensor imaging (DTI) data segmentation. The conventional partial volume segmentation method fails to classify voxels with multiple white matter (WM) fiber orientations such as fiber-crossing regions. Our purpose was to improve the performance of segmentation by taking into account the partial volume effects due to both multiple tissue types and multiple WM fiber orientations. We quantitatively evaluated the overall performance of the proposed method using digital DTI phantom data. Moreover, we applied our method to human DTI data, and compared our results with those of a conventional method. In the phantom experiments, the conventional method and proposed method yielded almost the same root mean square error (RMSE) for gray matter (GM) and cerebrospinal fluid (CSF), while the RMSE in the proposed method was smaller than that in the conventional method for WM. The volume overlap measures between our segmentation results and the ground truth of the digital phantom were more than 0.8 in all three tissue types, and were greater than those in the conventional method. In visual comparisons for human data, the WM/GM/CSF regions obtained using our method were in better agreement with the corresponding regions depicted in the structural image than those obtained using the conventional method. The results of the digital phantom experiment and human data demonstrated that our method improved accuracy in the segmentation of brain tissue data on DTI compared to the conventional method. PMID:23589185

Kumazawa, Seiji; Yoshiura, Takashi; Honda, Hiroshi; Toyofuku, Fukai

2013-12-01

135

Apparent molar volume, viscosity, and adiabatic compressibility of some mineral sulfates in aqueous binary mixtures of formamide at 298.15, 308.15, and 318.15 K  

NASA Astrophysics Data System (ADS)

The densities and viscosities of several sulfates, viz., ammonium sulfate, sodium sulfate, potassium sulfate, magnesium sulfate, zinc sulfate and cadmium sulfate in aqueous binary mixtures of formamide (FA) have been determined at 298.15, 308.15, and 318.15 K and at atmospheric pressure. The ultrasonic speeds of the electrolytic solutions have also been measured at 298.15 K. Apparent molar volumes (? V ), viscosity B-coefficients and adiabatic compressibilities ( K S) of these electrolytic solutions were calculated from the experimental densitiy, viscosity and acoustic data. The density and viscosity data were evaluated by using Masson’s and Jones-Dole equation respectively; the derived parameters have been analyzed in terms of ion-ion and ion-solvent interactions. The structure making/breaking capacities of the electrolytes have been inferred from the sign of (?2?{/V 0}/ ?T 2) P . The results showed that all the electrolytes act as structure-makers in these media. Also the compressibility data indicated electrostriction of the solvent molecules around the cations. The activation parameters of viscous flow were also determined and discussed by the application of transition state theory.

Roy, M. N.; Chanda, R.; Sarkar, B. K.

2009-10-01

136

The volume change for the dissociation of telluric acid  

Microsoft Academic Search

The hydrolysis constants of telluric acid were determined by potentiometric titrations at 25°C andI=1.0 mol kg-1 NaClO4. Using these results the partial molar volume change according to the dissociation reaction Te(OH)6(aq) ? TeO(OH)5(aq)-+H(aq)+ was measured densitymetrically.

Harald Marhold; Wolfgang Sagmüller; Heinz Gamsjäger

1988-01-01

137

Correction of a neutron diffraction peak shift due to a partial immersion of a gauge volume in an unstressed sample  

NASA Astrophysics Data System (ADS)

There exists an effect of variation of peak positions measured by neutron diffraction if the gauge volume is only partially immersed in a sample. In literature, this diffraction peak shift is known as pseudostrain or surface effect. The correction of the peak position on the pseudostrain effects may be made by analytical calculation or Monte Carlo simulation. We have developed a reductive analytical approach to account for the pseudostrain effect in a thin-walled sample using a concept of pseudo-time introduced by Creek et al. [4] for time-of-flight (TOF) neutron diffraction experiments. The approach was verified on the diffraction experimental data obtained by two groups of researchers [1,2] with a stress-free nickel powder sample. Our corrections of the pseudostrain effects in these experiments are very satisfactory.

Taran, Yu. V.; Balagurov, A. M.

2012-07-01

138

Taurodontism in deciduous molars.  

PubMed

Taurodont teeth are characterised by large pulp chambers at the expense of roots. An enlarged pulp chamber, apical displacement of the pulpal floor and no constriction at the level of the cement-enamel junction are the characteristic features of taurodont tooth. It appears more frequently as an isolated anomaly but its association with syndromes and other abnormalities have also been reported. Permanent dentition is more commonly affected than deciduous dentition. This paper presents a case report of taurodontism in relation to mandibular deciduous second molars. PMID:23737594

Bafna, Yash; Kambalimath, H V; Khandelwal, Vishal; Nayak, Prathibha

2013-01-01

139

Prosthetic rehabilitation of a hemisected maxillary molar: a rare entity.  

PubMed

Gingival recession beyond grade III and grade IV level involving furcation defects can lead to tooth loss if not intervened at appropriate time. The treatment options include scaling and root planing, Furcation-plasty, Tunnel preparation, Root separation and resection. The chief complaint of the patient was pain in the upper left first molar because of grade III furcation involvement. Since it was a four rooted molar, the treatment of choice was hemisection of the tooth and extraction of the distal half following endodontic treatment. As the second molar was mesially tilted the prosthodontic rehabilitation was done with a hybrid prosthesis involving a full coverage conventional porcelain fused to metal retainer on the hemisected molar and a resin bonded partial coverage retainer on the tilted second molar. The resultant prosthesis is termed as "Hybrid prosthesis". PMID:24431763

Yadav, Preeti; Tahir, Mohammed; Kumar, M V Sunil; Rao, Harikesh

2013-09-01

140

Ectopic molar pregnancy: a case report  

PubMed Central

The incidence of hydatidiform moles is 1 per 1,000 pregnancies. Ectopic pregnancy occurs in 20 per 1,000 pregnancies. Thus, the incidence of the ectopic molar gestation is very rare. We report a case of tubal molar pregnancy diagnosed at the systematic histology exam of an ectopic pregnancy. We report the case of 32 years old nulliparus women who presented a vaginal bleeding, lower abdominal pain and 6 weeks amenorrhea corresponding to the last menstrual period. At the clinical examination, the arterial pressure was 100/60 mmHG. The gynecological examination was difficult because of lower abdominal pain. Serum gonadotropin activity was 3454 ui/l. Pelvic ultrasound revealed an irregular echogenic mass in the left adnexa. Diagnostic laparoscopy revealed a left-sided unruptured ampullary ectopic pregnancy. A left laparoscopic salpingectomy was performed. The systematic histologic test identified an ectopic partial molar pregnancy, which was confirmed by DNA ploidy image analysis. The patient was followed with weekly quantitative B-hCG titers until three successive B-hCG levels were negative. It is pertinent that clinicians take routine histological examination of tubal specimens in ectopic pregnancy very seriously in order to diagnose cases of ectopic molar gestations early and mount appropriate post treatment surveillance.

Bousfiha, Najoua; Erarhay, Sanaa; Louba, Adnane; Saadi, Hanan; Bouchikhi, Chahrazad; Banani, Abdelaziz; Fatemi, Hind El; Sekkal, Med; Laamarti, Afaf

2012-01-01

141

Ectopic molar pregnancy: a case report.  

PubMed

The incidence of hydatidiform moles is 1 per 1,000 pregnancies. Ectopic pregnancy occurs in 20 per 1,000 pregnancies. Thus, the incidence of the ectopic molar gestation is very rare. We report a case of tubal molar pregnancy diagnosed at the systematic histology exam of an ectopic pregnancy. We report the case of 32 years old nulliparus women who presented a vaginal bleeding, lower abdominal pain and 6 weeks amenorrhea corresponding to the last menstrual period. At the clinical examination, the arterial pressure was 100/60 mmHG. The gynecological examination was difficult because of lower abdominal pain. Serum gonadotropin activity was 3454 ui/l. Pelvic ultrasound revealed an irregular echogenic mass in the left adnexa. Diagnostic laparoscopy revealed a left-sided unruptured ampullary ectopic pregnancy. A left laparoscopic salpingectomy was performed. The systematic histologic test identified an ectopic partial molar pregnancy, which was confirmed by DNA ploidy image analysis. The patient was followed with weekly quantitative B-hCG titers until three successive B-hCG levels were negative. It is pertinent that clinicians take routine histological examination of tubal specimens in ectopic pregnancy very seriously in order to diagnose cases of ectopic molar gestations early and mount appropriate post treatment surveillance. PMID:22655097

Bousfiha, Najoua; Erarhay, Sanaa; Louba, Adnane; Saadi, Hanan; Bouchikhi, Chahrazad; Banani, Abdelaziz; El Fatemi, Hind; Sekkal, Med; Laamarti, Afaf

2012-01-01

142

Improved Regional Activity Quantitation in Nuclear Medicine using a New Approach to Correct for Tissue Partial Volume and Spillover Effects  

PubMed Central

We have developed a new method of compensating for effects of partial volume and spillover in dual-modality imaging. The approach requires segmentation of just a few tissue types within a small VOI surrounding a lesion; the algorithm estimates simultaneously, from projection data, the activity concentration within each segmented tissue inside the VOI. Measured emission projections were fitted to the sum of resolution-blurred projections of each such tissue, scaled by its unknown activity concentration, plus a global background contribution obtained by reprojection through the reconstructed image volume outside the VOI. The method was evaluated using multiple-pinhole ?SPECT data simulated for the MOBY mouse phantom containing two spherical lung tumors and one liver tumor, as well as using multiple-bead phantom data acquired on ?SPECT and ?CT scanners. Each VOI in the simulation study was 4.8 mm (12 voxels) cubed and, depending on location, contained up to four tissues (tumor, liver, heart, lung) with different values of relative 99mTc concentration. All tumor activity estimates achieved <3% bias after ~15 OSEM iterations (× 10 subsets), with better than 8% precision (?25% greater than the Cramer-Rao lower bound). The projection-based fitting approach also outperformed three SUV-like metrics, one of which was corrected for count spillover. In the bead phantom experiment, the mean ± standard deviation of the bias of VOI estimates of bead concentration were 0.9 ± 9.5%, comparable to those of a perturbation geometric transfer matrix (pGTM) approach (-5.4 ± 8.6%); however, VOI estimates were more stable with increasing iteration number than pGTM estimates, even in the presence of substantial axial misalignment between ?CT and ?SPECT image volumes.

Moore, Stephen C.; Southekal, Sudeepti; Park, Mi-Ae; McQuaid, Sarah J.; Kijewski, Marie Foley; Muller, Stefan P.

2013-01-01

143

Comparative assessment of statistical brain MR image segmentation algorithms and their impact on partial volume correction in PET.  

PubMed

Magnetic resonance imaging (MRI)-guided partial volume effect correction (PVC) in brain positron emission tomography (PET) is now a well-established approach to compensate the large bias in the estimate of regional radioactivity concentration, especially for small structures. The accuracy of the algorithms developed so far is, however, largely dependent on the performance of segmentation methods partitioning MRI brain data into its main classes, namely gray matter (GM), white matter (WM), and cerebrospinal fluid (CSF). A comparative evaluation of three brain MRI segmentation algorithms using simulated and clinical brain MR data was performed, and subsequently their impact on PVC in 18F-FDG and 18F-DOPA brain PET imaging was assessed. Two algorithms, the first is bundled in the Statistical Parametric Mapping (SPM2) package while the other is the Expectation Maximization Segmentation (EMS) algorithm, incorporate a priori probability images derived from MR images of a large number of subjects. The third, here referred to as the HBSA algorithm, is a histogram-based segmentation algorithm incorporating an Expectation Maximization approach to model a four-Gaussian mixture for both global and local histograms. Simulated under different combinations of noise and intensity non-uniformity, MR brain phantoms with known true volumes for the different brain classes were generated. The algorithms' performance was checked by calculating the kappa index assessing similarities with the "ground truth" as well as multiclass type I and type II errors including misclassification rates. The impact of image segmentation algorithms on PVC was then quantified using clinical data. The segmented tissues of patients' brain MRI were given as input to the region of interest (RoI)-based geometric transfer matrix (GTM) PVC algorithm, and quantitative comparisons were made. The results of digital MRI phantom studies suggest that the use of HBSA produces the best performance for WM classification. For GM classification, it is suggested to use the EMS. Segmentation performed on clinical MRI data show quite substantial differences, especially when lesions are present. For the particular case of PVC, SPM2 and EMS algorithms show very similar results and may be used interchangeably. The use of HBSA is not recommended for PVC. The partial volume corrected activities in some regions of the brain show quite large relative differences when performing paired analysis on 2 algorithms, implying a careful choice of the segmentation algorithm for GTM-based PVC. PMID:16828315

Zaidi, Habib; Ruest, Torsten; Schoenahl, Frederic; Montandon, Marie-Louise

2006-10-01

144

Fifth alternative for replacement of maxillary first molar.  

PubMed

There are occasions when the patient is missing only one first molar or the first molar is slated for an odontectomy (extraction). Most of the time, there are only four common avenues for replacement: partial removable prosthesis, Maryland bridge, ceramic or ceramic to metal fixed prosthesis and osseo-integrated implant supported crown. In this article, the author discusses the least common avenue for replacement of missing maxillary first molar--an orthodontic closure. He discusses and demonstrates; Maximum, Medium and Minimum Anchorage strategies on acrylic models. Preserving the anchorage is necessary for successful execution of this orthodontic procedure. This demonstration is followed by presentation of the actual case. PMID:23941033

Palencar, Adrian J

2013-01-01

145

VAPOR PRESSURES, LIQUID MOLAR VOLUMES, VAPOR NON- IDEALITIES, AND CRITICAL PROPERTIES OF SOME FLUORINATED ETHERS: CF3OCF2OCF3, CF3OCF2 CF2H, c- CF2CF2CF2O, CF3OCF2H, AND CF3OCH3; AND OF CCl3F AND CF2ClH  

EPA Science Inventory

Vapor pressures, compressibilities, expansivities, and molar volumes of the liquid phase have been measured between room temperature and the critical temperature for a series of fluorinated ethers: CF3OCF2OCF3, CF3OCF2CF2H, c-CF2CF2CF2O, CF3OCF2H, and CF3OCH3. Vapor-phase non-ide...

146

Recovery of partial volume losses in cardiac mouse PET imaging using a combined 1D\\/2D and a combined 1D\\/3D model  

Microsoft Academic Search

Micro-PET image resolution is on the order of the left ventricle (LV) wall thickness in a mouse heart. Mouse LV images are thus subject to partial volume (PV) losses, impeding the ability to quantify tracer activity in cardiac muscle. In this study, 2D and 3D PV correction (PVC) models are proposed for mouse imaging. ECG gated PET images are acquired

Tyler Dumouchel; Robert A. de Kemp

2010-01-01

147

Fluid and deformation induced partial melting and melt volumes in low-temperature granulite-facies metasediments, Damara Belt, Namibia  

NASA Astrophysics Data System (ADS)

Fluid-present partial melting has generally been regarded a poor candidate for effecting crustal differentiation. In this study we report on granulite-grade metasediments from the Pan-African Damara Belt in Namibia that have undergone fluid-present biotite melting at a relatively low-temperature, yet appear to have lost a significant volume of melt. In situ anatectic features have been identified on the basis of the existence of new generations of cordierite and/or garnet produced as the solid products of incongruent anatexis within or adjacent to leucosomes. Leucosomes occur in lens-shaped pods that are orientated at high angles to the regional stretching lineation that formed during orogen-parallel extrusion of the rocks during the main collisional event in the Damara Belt. Within these sites biotite underwent incongruent melting via the reaction Bt + Qtz + Pl + H 2O = Melt + Grt + Crd. Cordierite nucleated on pre-existing crystals within the bounding gneiss; garnet nucleated within the fracture sites (leucosomes) and typically occurs as individual, large (50 to 120 mm) poikiloblastic crystals. Thermobarometry applied to the anatectic assemblage yields low-temperature, granulite-facies peak conditions of 750 °C, 0.5 GPa. This temperature is approximately 100 °C lower than the accepted conditions for the onset of fluid-absent biotite melting. This, coupled to the focussing of anatexis on dilational sites, suggests that anatexis occurred through water-present biotite incongruent melting. In order to better understand this process, both fluid-absent and water-present partial melting experiments were conducted within the temperature interval 700 to 900 °C at 0.7 GPa. In the fluid-absent experiments, biotite incongruent melting started between 800 and 850 °C to produce melt coexisting with peritectic garnet and cordierite. In contrast, in water-saturated experiments, biotite melted via the reaction Bt + Qtz + Pl + H 2O = Melt + Grt + Crd, between 700 and 750 °C, to produce melt, cordierite and garnet in the proportions 73:24:3. The garnet compositions produced in these low-temperature experiments match very well with the relatively high spessartine content (10%), low Mg# garnets formed with the leucosomes, confirming the water-saturated, low-temperature nature of anatexis in the study area. Mass balance calculations indicate that melting in typical dilational sites has produced 6 dm 3 of melt. This melt has been sourced from some 0.08 m 3 of rock, a volume that coincides well with the typical frequency of extensional fracture spacing. This was probably important in enabling efficient melt extraction which has caused a slight shift towards more refractory compositions in the granulite-facies metapelites over amphibolite-facies equivalents. However, the attendant expansion in chemical equilibration volume has resulted in a marked compositional homogenization of the high-grade gneisses over the rhythmically bedded amphibolite-facies metapelites.

Ward, Robert; Stevens, Gary; Kisters, Alex

2008-10-01

148

A three-dimensional model-based partial volume correction strategy for gated cardiac mouse PET imaging  

NASA Astrophysics Data System (ADS)

Quantification in cardiac mouse positron emission tomography (PET) imaging is limited by the imaging spatial resolution. Spillover of left ventricle (LV) myocardial activity into adjacent organs results in partial volume (PV) losses leading to underestimation of myocardial activity. A PV correction method was developed to restore accuracy of the activity distribution for FDG mouse imaging. The PV correction model was based on convolving an LV image estimate with a 3D point spread function. The LV model was described regionally by a five-parameter profile including myocardial, background and blood activities which were separated into three compartments by the endocardial radius and myocardium wall thickness. The PV correction was tested with digital simulations and a physical 3D mouse LV phantom. In vivo cardiac FDG mouse PET imaging was also performed. Following imaging, the mice were sacrificed and the tracer biodistribution in the LV and liver tissue was measured using a gamma-counter. The PV correction algorithm improved recovery from 50% to within 5% of the truth for the simulated and measured phantom data and image uniformity by 5-13%. The PV correction algorithm improved the mean myocardial LV recovery from 0.56 (0.54) to 1.13 (1.10) without (with) scatter and attenuation corrections. The mean image uniformity was improved from 26% (26%) to 17% (16%) without (with) scatter and attenuation corrections applied. Scatter and attenuation corrections were not observed to significantly impact PV-corrected myocardial recovery or image uniformity. Image-based PV correction algorithm can increase the accuracy of PET image activity and improve the uniformity of the activity distribution in normal mice. The algorithm may be applied using different tracers, in transgenic models that affect myocardial uptake, or in different species provided there is sufficient image quality and similar contrast between the myocardium and surrounding structures.

Dumouchel, Tyler; Thorn, Stephanie; Kordos, Myra; DaSilva, Jean; Beanlands, Rob S. B.; deKemp, Robert A.

2012-07-01

149

METHODS DEVELOPMENT FOR ASSESSING AIR POLLUTION CONTROL BENEFITS. VOLUME IV. STUDIES ON PARTIAL EQUILIBRIUM APPROACHES TO VALUATION OF ENVIRONMENTAL AMENITIES  

EPA Science Inventory

The research presented in this volume of a five volume study of the economic benefits of air pollution control explores various facets of the two central project objectives that have not been given adequate attention in the previous volumes. The valuations developed in these prev...

150

Lung Dose-Volume Parameters and the Risk of Pneumonitis for Patients Treated With Accelerated Partial-Breast Irradiation Using Three-Dimensional Conformal Radiotherapy  

Microsoft Academic Search

Purpose There are no data on how complication rates after accelerated partial-breast irradiation delivered by three-dimensional conformal radiotherapy are affected by treatment technique. We therefore examined the risk of pneumonitis in relation to lung dose-volume parameters. Patients and Methods Our prospective dose-escalation trial enrolled 198 treated patients from 2003 to 2007. Patients received 32 or 36 Gy in 4-Gy fractions,

Abram Recht; Marek Ancukiewicz; M. A. Alm El-Din; Xing-Qi Lu; Chrystalla Martin; Stuart M. Berman; Ariel E. Hirsch; Lisa A. Kachnic; Angela Katz; Shannon MacDonald; Elena A. Nedea; Mary Ann Stevenson; Simon N. Powell; Alphonse G. Taghian

2009-01-01

151

Solutions : WtPercentToMolarity (4 Variations)  

NSDL National Science Digital Library

A common concentration unit used commercially is percent weight per volume (%W/V) which is the number of grams of solute in 100 mL of solution. A bottle of vinegar contains 5 %W/V acetic acid (CH 3 COOH). What is the molar concentration of acetic acid in the vinegar?

152

Molar Incisor Hypomineralization, Prevalence, and Etiology  

PubMed Central

Aim. To evaluate the prevalence and possible etiological factors associated with molar incisor hypomineralization (MIH) among a group of children in Jeddah, Saudi Arabia. Methods. A group of 8-12-year-old children were recruited (n = 267) from the Pediatric Dental Clinics at the Faculty of Dentistry, King Abdulaziz University. Children had at least one first permanent molar (FPM), erupted or partially erupted. Demographic information, children's medical history, and pregnancy-related data were obtained. The crowns of the FPM and permanent incisors were examined for demarcated opacities, posteruptive breakdown (PEB), atypical restorations, and extracted FPMs. Children were considered to have MIH if one or more FPM with or without involvement of incisors met the diagnostic criteria. Results. MIH showed a prevalence of 8.6%. Demarcated opacities were the most common form. Maxillary central incisors were more affected than mandibular (P = 0.01). The condition was more prevalent in children with history of illnesses during the first four years of life including tonsillitis (P = 0.001), adenoiditis (P = 0.001), asthma (P = 0.001), fever (P = 0.014), and antibiotics intake (P = 0.001). Conclusions. The prevalence of MIH is significantly associated with childhood illnesses during the first four years of life including asthma, adenoid infections, tonsillitis, fever, and antibiotics intake.

Allazzam, Sulaiman Mohammed; Alaki, Sumer Madani; El Meligy, Omar Abdel Sadek

2014-01-01

153

Process Duration and Water Consumption in a Variable Volume Diafiltration for Partial Demineralization and Concentration of Acid Whey  

Microsoft Academic Search

Process duration and fresh water consumption were determined (experimentally and statistically) for variable volume diafiltration (VVD) of cottage cheese through a flat sheet membrane (0.046 m). The VVD process was performed at two volume decreasing ratios (? = 0.75 and ? = 0.5). The VVD-0.75 process lasts much longer than the VVD-0.5 process if the same concentration degree is required. The VVD-0.5 process lasts longer

András Román; Svetlana Popovi?; Gyula Vatai; Mirjana Djuri?; Miodrag N. Teki?

2010-01-01

154

Geometric morphometric 3D shape analysis and covariation of human mandibular and maxillary first molars.  

PubMed

Dental casts of 160 Greek subjects (80 males, 80 females) were scanned by a structured-light scanner. The upper and lower right first molar occlusal surface 3D meshes were processed using geometric morphometric methods. A total of 265 and 274 curve and surface sliding semilandmarks were placed on the upper and lower molar surfaces, respectively. Principal component analysis and partial least square analysis were performed to assess shape parameters. Molars tended to vary between an elongated and a more square form. The first two principal components (PCs), comprising almost 1/3 of molar shape variation, were related to mesiodistal-buccolingual ratios and relative cusp position. Distal cusps displayed the greatest shape variability. Molars of males were larger than those of females (2.8 and 3.2% for upper and lower molars respectively), but no shape dimorphism was observed. Upper and lower molar sizes were significantly correlated (r(2) = 0.689). Allometry was observed for both teeth. Larger lower molars were associated with shorter cusps, expansion of the distal cusp, and constriction of the mesial cusps (predicted variance 3.25%). Upper molars displayed weaker allometry (predicted variance 1.59%). Upper and lower molar shape covariation proved significant (RV = 17.26%, P < 0.0001). The main parameter of molar covariation in partial least square axis 1, contributing to 30% of total covariation, was cusp height, in contrast to the primary variability traits exhibited by PC1 and PC2. The aim of this study was to evaluate shape variation and covariation, including allometry and sexual dimorphism, of maxillary and mandibular first permanent molar occlusal surfaces. PMID:24009105

Polychronis, Georgios; Christou, Panagiotis; Mavragani, Maria; Halazonetis, Demetrios J

2013-10-01

155

Measurement of D2 dopamine receptor-specific carbon-11-YM-09151-2 binding in the canine brain by PET: Importance of partial volume correction  

SciTech Connect

Carbon-11-YM-09151-2 binds highly selectively to D2 dopamine receptors in the brain. Using this ligand, D2 dopamine receptor density (Bmax) and affinity (Kd) in canine striatum were measured. After administering various doses of the ligand in nine experiments, regional uptake was followed by repeated PET scanning for up to 80 min. D2 dopamine receptor specific binding at equilibrium was defined as striatal minus occipital activity after partial volume correction. Bmax and Kd were estimated by Scatchard analysis to be 40.3 pmole/ml of tissue and 22.9 nM, respectively. When a low mass dose of the ligand was administered, the bound-to-free ligand ratio in the striatum at equilibrium was consistent with the Bmax/Kd value obtained from the Scatchard analysis. The present study demonstrates the importance of partial volume correction and the Bmax/Kd measurement in a single PET study with carbon-11-YM-09151-2.

Hatazawa, J.; Hatano, K.; Ishiwata, K.; Itoh, M.; Ido, T.; Kawashima, K.; Meguro, K.; Watanuki, S.; Seo, S. (Tohoku Univ., Sendai (Japan))

1991-04-01

156

Molar distalization with the Herbst appliance  

Microsoft Academic Search

This article reviews the dental effects of the Herbst appliance as well as itslong-term effects on the dentition. The Herbst appliance exhibits a pronounced high-pull headgear effect on the maxillary molars. Without retention, the molars tend to return to their former anteroposterior positions after the removal of the appliance. These distal movements of the maxillary molars are favorable in Class

Meson Lai

2000-01-01

157

Quantification accuracy and partial volume effect in dependence of the attenuation correction of a state-of-the-art small animal PET scanner  

NASA Astrophysics Data System (ADS)

Quantification accuracy and partial volume effect (PVE) of the Siemens Inveon PET scanner were evaluated. The influence of transmission source activities (40 and 160 MBq) on the quantification accuracy and the PVE were determined. Dynamic range, object size and PVE for different sphere sizes, contrast ratios and positions in the field of view (FOV) were evaluated. The acquired data were reconstructed using different algorithms and correction methods. The activity level of the transmission source and the total emission activity in the FOV strongly influenced the attenuation maps. Reconstruction algorithms, correction methods, object size and location within the FOV had a strong influence on the PVE in all configurations. All evaluated parameters potentially influence the quantification accuracy. Hence, all protocols should be kept constant during a study to allow a comparison between different scans.

Mannheim, Julia G.; Judenhofer, Martin S.; Schmid, Andreas; Tillmanns, Julia; Stiller, Detlef; Sossi, Vesna; Pichler, Bernd J.

2012-06-01

158

PET imaging of thin objects: measuring the effects of positron range and partial-volume averaging in the leag of Nicotiana Tabacum  

SciTech Connect

PET imaging in plants is receiving increased interest as a new strategy to measure plant responses to environmental stimuli and as a tool for phenotyping genetically engineered plants. PET imaging in plants, however, poses new challenges. In particular, the leaves of most plants are so thin that a large fraction of positrons emitted from PET isotopes ({sup 18}F, {sup 11}C, {sup 13}N) escape while even state-of-the-art PET cameras have significant partial-volume errors for such thin objects. Although these limitations are acknowledged by researchers, little data have been published on them. Here we measured the magnitude and distribution of escaping positrons from the leaf of Nicotiana tabacum for the radionuclides {sup 18}F, {sup 11}C and {sup 13}N using a commercial small-animal PET scanner. Imaging results were compared to radionuclide concentrations measured from dissection and counting and to a Monte Carlo simulation using GATE (Geant4 Application for Tomographic Emission). Simulated and experimentally determined escape fractions were consistent. The fractions of positrons (mean {+-} S.D.) escaping the leaf parenchyma were measured to be 59 {+-} 1.1%, 64 {+-} 4.4% and 67 {+-} 1.9% for {sup 18}F, {sup 11}C and {sup 13}N, respectively. Escape fractions were lower in thicker leaf areas like the midrib. Partial-volume averaging underestimated activity concentrations in the leaf blade by a factor of 10 to 15. The foregoing effects combine to yield PET images whose contrast does not reflect the actual activity concentrations. These errors can be largely corrected by integrating activity along the PET axis perpendicular to the leaf surface, including detection of escaped positrons, and calculating concentration using a measured leaf thickness.

Alexoff, D.L.; Alexoff, D.L.; Dewey, S.L.; Vaska, P.; Krishnamoorthy, S.; Ferrieri, R.; Schueller, M.; Schlyer, D.; Fowler, J.S.

2011-03-01

159

The Effect of Dose-Volume Parameters and Interfraction Interval on Cosmetic Outcome and Toxicity After 3-Dimensional Conformal Accelerated Partial Breast Irradiation  

SciTech Connect

Purpose: To evaluate dose-volume parameters and the interfraction interval (IFI) as they relate to cosmetic outcome and normal tissue effects of 3-dimensional conformal radiation therapy (3D-CRT) for accelerated partial breast irradiation (APBI). Methods and Materials: Eighty patients were treated by the use of 3D-CRT to deliver APBI at our institutions from 2003-2010 in strict accordance with the specified dose-volume constraints outlined in the National Surgical Adjuvant Breast and Bowel Project B39/Radiation Therapy Oncology Group 0413 (NSABP-B39/RTOG 0413) protocol. The prescribed dose was 38.5 Gy in 10 fractions delivered twice daily. Patients underwent follow-up with assessment for recurrence, late toxicity, and overall cosmetic outcome. Tests for association between toxicity endpoints and dosimetric parameters were performed with the chi-square test. Univariate logistic regression was used to evaluate the association of interfraction interval (IFI) with these outcomes. Results: At a median follow-up time of 32 months, grade 2-4 and grade 3-4 subcutaneous fibrosis occurred in 31% and 7.5% of patients, respectively. Subcutaneous fibrosis improved in 5 patients (6%) with extended follow-up. Fat necrosis developed in 11% of women, and cosmetic outcome was fair/poor in 19%. The relative volume of breast tissue receiving 5%, 20%, 50%, 80%, and 100% (V5-V100) of the prescribed dose was associated with risk of subcutaneous fibrosis, and the volume receiving 50%, 80%, and 100% (V50-V100) was associated with fair/poor cosmesis. The mean IFI was 6.9 hours, and the minimum IFI was 6.2 hours. The mean and minimum IFI values were not significantly associated with late toxicity. Conclusions: The incidence of moderate to severe late toxicity, particularly subcutaneous fibrosis and fat necrosis and resulting fair/poor cosmesis, remains high with continued follow-up. These toxicity endpoints are associated with several dose-volume parameters. Minimum and mean IFI values were not associated with late toxicity.

Leonard, Kara Lynne, E-mail: karalynne.kerr@gmail.com [Department of Radiation Oncology, Tufts University School of Medicine, Boston, Massachusetts (United States); Hepel, Jaroslaw T. [Department of Radiation Oncology, Tufts University School of Medicine, Boston, Massachusetts (United States) [Department of Radiation Oncology, Tufts University School of Medicine, Boston, Massachusetts (United States); Department of Radiation Oncology, Rhode Island Hospital, Warren Alpert School of Medicine of Brown University, Providence, Rhode Island (United States); Hiatt, Jessica R. [Department of Radiation Oncology, Rhode Island Hospital, Warren Alpert School of Medicine of Brown University, Providence, Rhode Island (United States)] [Department of Radiation Oncology, Rhode Island Hospital, Warren Alpert School of Medicine of Brown University, Providence, Rhode Island (United States); Dipetrillo, Thomas A. [Department of Radiation Oncology, Tufts University School of Medicine, Boston, Massachusetts (United States) [Department of Radiation Oncology, Tufts University School of Medicine, Boston, Massachusetts (United States); Department of Radiation Oncology, Rhode Island Hospital, Warren Alpert School of Medicine of Brown University, Providence, Rhode Island (United States); Price, Lori Lyn [Department of Biostatistics Research Center, Institute of Clinical Research and Health Policy Studies, Tufts Medical Center, Boston, Massachusetts (United States)] [Department of Biostatistics Research Center, Institute of Clinical Research and Health Policy Studies, Tufts Medical Center, Boston, Massachusetts (United States); Wazer, David E. [Department of Radiation Oncology, Tufts University School of Medicine, Boston, Massachusetts (United States) [Department of Radiation Oncology, Tufts University School of Medicine, Boston, Massachusetts (United States); Department of Radiation Oncology, Rhode Island Hospital, Warren Alpert School of Medicine of Brown University, Providence, Rhode Island (United States)

2013-03-01

160

MB2 in maxillary second molar.  

PubMed

Occurrence of the second mesiobuccal canal (MB2) is a frequent finding. Literary reports have shown it to be found more in the cases of the maxillary first molar. However the maxillary second molars have also been found with this variation in a number of canals. This paper presents a case report on the occurrence of a second mesiobuccal canal or the MB2 in the maxillary second molar. PMID:17347545

Prakash, R; Bhargavi, N; Rajan, Jeyavel; Joseph, Reuben; Velmurugan, N; Kandaswamy, D

2007-01-01

161

Maxillary First Molar with Two Root Canals  

PubMed Central

Knowledge regarding the anatomic morphology of maxillary molars is absolutely essential for the success of endodontic treatment. The morphology of the permanent maxillary first molar has been reviewed extensively; however, the presence of two canals in a two-rooted maxillary first molar has rarely been reported in studies describing tooth and root canal anatomies. This case report presents a patient with a maxillary first molar with two roots and two root canals, who was referred to the Department of Endodontics, Tabriz University of Medical Sciences, Iran.

Rahimi, Saeed; Ghasemi, Negin

2013-01-01

162

Mandibular molar root morphology in Neanderthals and Late Pleistocene and recent Homo sapiens.  

PubMed

Neanderthals have a distinctive suite of dental features, including large anterior crown and root dimensions and molars with enlarged pulp cavities. Yet, there is little known about variation in molar root morphology in Neanderthals and other recent and fossil members of Homo. Here, we provide the first comprehensive metric analysis of permanent mandibular molar root morphology in Middle and Late Pleistocene Homo neanderthalensis, and Late Pleistocene (Aterian) and recent Homo sapiens. We specifically address the question of whether root form can be used to distinguish between these groups and assess whether any variation in root form can be related to differences in tooth function. We apply a microtomographic imaging approach to visualise and quantify the external and internal dental morphologies of both isolated molars and molars embedded in the mandible (n=127). Univariate and multivariate analyses reveal both similarities (root length and pulp volume) and differences (occurrence of pyramidal roots and dental tissue volume proportion) in molar root morphology among penecontemporaneous Neanderthals and Aterian H. sapiens. In contrast, the molars of recent H. sapiens are markedly smaller than both Pleistocene H. sapiens and Neanderthals, but share with the former the dentine volume reduction and a smaller root-to-crown volume compared with Neanderthals. Furthermore, we found the first molar to have the largest average root surface area in recent H. sapiens and Neanderthals, although in the latter the difference between M(1) and M(2) is small. In contrast, Aterian H. sapiens root surface areas peak at M(2). Since root surface area is linked to masticatory function, this suggests a distinct occlusal loading regime in Neanderthals compared with both recent and Pleistocene H. sapiens. PMID:20719359

Kupczik, Kornelius; Hublin, Jean-Jacques

2010-11-01

163

Impact of partial-volume effect correction on the predictive and prognostic value of baseline 18F-FDG PET images in esophageal cancer  

PubMed Central

The objectives of this study were to investigate the clinical impact of partial volume effects (PVE) correction on the predictive and prognostic value of metabolically active tumor volume (MATV) measurements on 18F-FDG PET baseline scan for therapy response and overall survival in esophageal cancer patients. Methods 50 patients with esophageal cancer treated with concomitant radio-chemotherapy between 2004 and 2008 were retrospectively considered. PET baseline scans were corrected for PVE with iterative deconvolution incorporating wavelet denoising. MATV delineation on both original and corrected images was carried out using the automatic Fuzzy Locally Adaptive Bayesian (FLAB) methodology. Several parameters were extracted considering the original and corrected images: maximum and peak SUV, mean SUV, MATV and TLG (TLG=MATV×mean SUV). The predictive value of each parameter with or without correction was investigated using Kruskal-Wallis tests and the prognostic value with Kaplan-Meier curves. Results Whereas PVE correction had significant quantitative impact on the absolute values of the investigated parameters, their clinical value within the clinical context of interest was not significantly modified. This was observed for both overall survival and response to therapy. The hierarchy between parameters was the same before and after correction. SUV measurements (max, peak, mean) had non-significant (p>0.05) predictive or prognostic value, whereas functional tumor related measurements (MATV, TLG) were significant (p<0.002) predictors of response and independent prognostic factors. Conclusions PVE correction does not improve the predictive and prognostic value of baseline PET image derived parameters in esophageal cancer patients.

Hatt, Mathieu; Le Pogam, Adrien; Visvikis, Dimitris; Pradier, Olivier; Cheze Le Rest, Catherine

2012-01-01

164

A Prospective Pathologic Study to Define the Clinical Target Volume for Partial Breast Radiation Therapy in Women With Early Breast Cancer  

SciTech Connect

Purpose: To determine an appropriate clinical target volume for partial breast radiation therapy (PBRT) based on the spatial distribution of residual invasive and in situ carcinoma after wide local excision (WLE) for early breast cancer or ductal carcinoma in situ (DCIS). Methods and Materials: We performed a prospective pathologic study of women potentially eligible for PBRT who had re-excision and/or completion mastectomy after WLE for early breast cancer or DCIS. A pathologic assessment protocol was used to determine the maximum radial extension (MRE) of residual carcinoma from the margin of the initial surgical cavity. Women were stratified by the closest initial radial margin width: negative (>1 mm), close (>0 mm and {<=}1 mm), or involved. Results: The study population was composed of 133 women with a median age of 59 years (range, 27-82 years) and the following stage groups: 0 (13.5%), I (40.6%), II (38.3%), and III (7.5%). The histologic subtypes of the primary tumor were invasive ductal carcinoma (74.4%), invasive lobular carcinoma (12.0%), and DCIS alone (13.5%). Residual carcinoma was present in the re-excision and completion mastectomy specimens in 55.4%, 14.3%, and 7.2% of women with an involved, close, and negative margin, respectively. In the 77 women with a noninvolved radial margin, the MRE of residual disease, if present, was {<=}10 mm in 97.4% (95% confidence interval 91.6-99.5) of cases. Larger MRE measurements were significantly associated with an involved margin (P<.001), tumor size >30 mm (P=.03), premenopausal status (P=.03), and negative progesterone receptor status (P=.05). Conclusions: A clinical target volume margin of 10 mm would encompass microscopic residual disease in >90% of women potentially eligible for PBRT after WLE with noninvolved resection margins.

Nguyen, Brandon T., E-mail: Brandon.Nguyen@act.gov.au [Department of Radiation Oncology, Peter MacCallum Cancer Centre, East Melbourne, Victoria (Australia); Canberra Hospital, Radiation Oncology Department, Garran, ACT (Australia); Deb, Siddhartha [Department of Anatomical Pathology, Peter MacCallum Cancer Centre, East Melbourne, Victoria (Australia) [Department of Anatomical Pathology, Peter MacCallum Cancer Centre, East Melbourne, Victoria (Australia); Victorian Cancer Biobank, Cancer Council of Victoria, Carlton, Victoria (Australia); Fox, Stephen [Department of Anatomical Pathology, Peter MacCallum Cancer Centre, East Melbourne, Victoria (Australia)] [Department of Anatomical Pathology, Peter MacCallum Cancer Centre, East Melbourne, Victoria (Australia); Hill, Prudence [Department of Anatomical Pathology, St. Vincent's Hospital Melbourne, Fitzroy, Victoria (Australia)] [Department of Anatomical Pathology, St. Vincent's Hospital Melbourne, Fitzroy, Victoria (Australia); Collins, Marnie [Centre for Biostatistics and Clinical Trials, Peter MacCallum Cancer Centre, East Melbourne, Victoria (Australia)] [Centre for Biostatistics and Clinical Trials, Peter MacCallum Cancer Centre, East Melbourne, Victoria (Australia); Chua, Boon H. [Department of Radiation Oncology, Peter MacCallum Cancer Centre, East Melbourne, Victoria (Australia) [Department of Radiation Oncology, Peter MacCallum Cancer Centre, East Melbourne, Victoria (Australia); University of Melbourne, Parkville, Victoria (Australia)

2012-12-01

165

Histological evaluation of mandibular third molar roots retrieved after coronectomy.  

PubMed

There is a resurgence of interest in coronectomy for the management of mandibular third molars because it has a low risk of injury to the inferior dental nerve. However, there is concern that the root that is left in place will eventually become a source of infection. We describe the histological evaluation of 26 consecutive symptomatic coronectomy roots in 21 patients. All roots had vital tissue in the pulp chamber and there was no evidence of periradicular inflammation. Persistent postoperative symptoms related predominantly to inflammation of the soft tissue, which was caused by partially erupted roots or failure of the socket to heal. PMID:24684971

Patel, Vinod; Sproat, Chris; Kwok, Jerry; Beneng, Kiran; Thavaraj, Selvam; McGurk, Mark

2014-05-01

166

Unilateral molar distalization with a modified slider.  

PubMed

Although there are numerous publications on bilateral non-compliance molar distalization appliances, there is limited information on problems such as asymmetrical unilateral Class II malocclusions. The aim of the present investigation was to examine the distalization of molars unilaterally in patients with a unilateral Class II molar relationship utilizing a Keles Slider, designed without a bite plane. Ten girls (mean age 13.94 +/- 2.13 years) and seven boys (mean age 13.12 +/- 1.51 years) comprised the study material. Following insertion of the appliance, the patients were seen monthly and the screw was reactivated every 2 months. After a super-Class I molar relationship was achieved, the appliance was removed and the molars were stabilized with a Nance appliance for 2 months before the second-phase of orthodontic treatment. The Nance appliance was maintained in the palate until the end of canine distalization. Lateral cephalometric radiographs were obtained before and immediately after insertion of the molar distalizer. The results showed that the maxillary first molars were distalized bodily on average by 2.85 mm. The maxillary first premolars moved forward bodily 2 mm and were extruded 2.03 mm. In all, 1.32 mm of protrusion, 1.12 mm of extrusion, and 1.79 degrees of proclination of the upper incisors were observed. The mandibular incisors and mandibular molars erupted 0.83 and 0.95 mm, respectively. The unilateral Keles Slider distalized molars successfully to a Class I molar relationship. PMID:16648210

Sayinsu, Korkmaz; Isik, Fulya; Allaf, Ferdi; Arun, Tülin

2006-08-01

167

Improving Dynamic Susceptibility Contrast MRI Measurement of Quantitative Cerebral Blood Flow using Corrections for Partial Volume and Nonlinear Contrast Relaxivity: a Xenon CT Comparative Study  

PubMed Central

Purpose To test whether dynamic susceptibility contrast MRI-based CBF measurements are improved with arterial input function (AIF) partial volume (PV) and nonlinear contrast relaxivity correction, using a gold-standard CBF method, xenon computed tomography (xeCT). Materials and Methods 18 patients with cerebrovascular disease underwent xeCT and MRI within 36 hrs. PV was measured as the ratio of the area under the AIF and the venous output function (VOF) concentration curves. A correction was applied to account for the nonlinear relaxivity of bulk blood (BB). Mean CBF was measured with both techniques and regression analyses both within and between patients were performed. Results Mean xeCT CBF was 43.3±13.7 ml/100g/min (mean±SD). BB correction decreased CBF by a factor of 4.7±0.4, but did not affect precision. The least-biased CBF measurement was with BB but without PV correction (45.8±17.2 ml/100 g/min, coefficient of variation [COV]=32%). Precision improved with PV correction, although absolute CBF was mildly underestimated (34.3±10.8 ml/100 g/min, COV=27%). Between patients correlation was moderate even with both corrections (R=0.53). Conclusion Corrections for AIF PV and nonlinear BB relaxivity improve bolus MRI-based CBF maps. However, there remain challenges given the moderate between-patient correlation, which limit diagnostic confidence of such measurements in individual patients.

Zaharchuk, Greg; Bammer, Roland; Straka, Matus; Newbould, Rexford D; Rosenberg, Jarrett; Olivot, Jean-Marc; Mlynash, Michael; Lansberg, Maarten G; Schwartz, Neil E; Marks, Michael M; Albers, Gregory W; Moseley, Michael E

2010-01-01

168

Integration of 3D Scale-based Pseudo-enhancement Correction and Partial Volume Image Segmentation for Improving Electronic Colon Cleansing in CT Colonograpy  

PubMed Central

Orally administered tagging agents are usually used in CT colonography (CTC) to differentiate residual bowel content from native colonic structures. However, the high-density contrast agents tend to introduce pseudo-enhancement (PE) effect on neighboring soft tissues and elevate their observed CT attenuation value toward that of the tagged materials (TMs), which may result in an excessive electronic colon cleansing (ECC) since the pseudo-enhanced soft tissues are incorrectly identified as TMs. To address this issue, we integrated a 3D scale-based PE correction into our previous ECC pipeline based on the maximum a posteriori expectation-maximization partial volume (PV) segmentation. The newly proposed ECC scheme takes into account both the PE and PV effects that commonly appear in CTC images. We evaluated the new scheme on 40 patient CTC scans, both qualitatively through display of segmentation results, and quantitatively through radiologists’ blind scoring (human observer) and computer-aided detection (CAD) of colon polyps (computer observer). Performance of the presented algorithm has shown consistent improvements over our previous ECC pipeline, especially for the detection of small polyps submerged in the contrast agents. The CAD results of polyp detection showed that 4 more submerged polyps were detected for our new ECC scheme over the previous one.

Zhang, Hao; Li, Lihong; Zhu, Hongbin; Han, Hao; Song, Bowen; Liang, Zhengrong

2014-01-01

169

Assessment of the severity of partial volume effects and the performance of two template-based correction methods in a SPECT/CT phantom experiment  

NASA Astrophysics Data System (ADS)

We investigated the severity of partial volume effects (PVE), which may occur in SPECT/CT studies, and the performance of two template-based correction techniques. A hybrid SPECT/CT system was used to scan a thorax phantom that included lungs, a heart insert and six cylindrical containers of different sizes and activity concentrations. This phantom configuration allowed us to have non-uniform background activity and a combination of spill-in and spill-out effects for several compartments. The reconstruction with corrections for attenuation, scatter and resolution loss but not PVE correction accurately recovered absolute activities in large organs. However, the activities inside segmented 17-120 mL containers were underestimated by 20%-40%. After applying our PVE correction to the data pertaining to six small containers, the accuracy of the recovered total activity improved with errors ranging between 3% and 22% (non-iterative method) and between 5% and 15% (method with an iteratively updated background activity). While the non-iterative template-based algorithm demonstrated slightly better accuracy for cases with less severe PVE than the iterative algorithm, it underperformed in situations with considerable spill out and/or mixture of spill-in and spill-out effects.

Shcherbinin, S.; Celler, A.

2011-08-01

170

Integration of 3D scale-based pseudo-enhancement correction and partial volume image segmentation for improving electronic colon cleansing in CT colonograpy.  

PubMed

Orally administered tagging agents are usually used in CT colonography (CTC) to differentiate residual bowel content from native colonic structures. However, the high-density contrast agents tend to introduce pseudo-enhancement (PE) effect on neighboring soft tissues and elevate their observed CT attenuation value toward that of the tagged materials (TMs), which may result in an excessive electronic colon cleansing (ECC) since the pseudo-enhanced soft tissues are incorrectly identified as TMs. To address this issue, we integrated a 3D scale-based PE correction into our previous ECC pipeline based on the maximum a posteriori expectation-maximization partial volume (PV) segmentation. The newly proposed ECC scheme takes into account both the PE and PV effects that commonly appear in CTC images. We evaluated the new scheme on 40 patient CTC scans, both qualitatively through display of segmentation results, and quantitatively through radiologists' blind scoring (human observer) and computer-aided detection (CAD) of colon polyps (computer observer). Performance of the presented algorithm has shown consistent improvements over our previous ECC pipeline, especially for the detection of small polyps submerged in the contrast agents. The CAD results of polyp detection showed that 4 more submerged polyps were detected for our new ECC scheme over the previous one. PMID:24699352

Zhang, Hao; Li, Lihong; Zhu, Hongbin; Han, Hao; Song, Bowen; Liang, Zhengrong

2014-01-01

171

Volume Change due to Intermetallic Compound Formation at the Al-Au Bond in Semiconductor Devices  

NASA Astrophysics Data System (ADS)

The molar volume of an Al-Au intermetallic compound was calculated and compared with those of Al and Au individually. It is well known that, though the molar volume of an AlAu4 compound is smaller than the sum of those of Al and Au, it is larger than that of Al. It is shown that this fact can be explained by taking into consideration the differences between the densities of Al, Au and Al-Au alloys and the component ratio of the compound. Practically, it is pointed out that this volume effect can induce pores at an imperfect bond between Al films and Au wires in Si devices. This suggests that such partial openings should be distinguished from Kirkendall voids.

Kato, Hiroshi

1986-06-01

172

Third molar eruption among rural Nigerians.  

PubMed

Times of eruption of third molars were studied in rural Nigerian adolescents--125 males and 133 females. Results of this study showed that the average age for the initial eruption of third molars was 15 years in male subjects and 13 years for female subjects. The incidence of eruption showed a steep rise after the age of 16 years for male subjects and 14 years for female subjects. By the age of 19 years, all third molars had erupted into the oral cavity. The eruption of lower third molars was generally ahead of the upper third molars for all age groups. The results of this study suggest that (1) the timing of third molar eruption is strongly influenced by the availability of mandibular trigone space, (2) the attrition and shrinkage of the dental arch, probably as the result of nonrefined highly fibrous diets, produce larger mandibular trigone spaces, and (3) the early eruption of third molars observed in the present study may be due to the nature of the diet used and the vigorous employment of the masticatory apparatus (from infancy) by the subjects examined. PMID:2003009

Odusanya, S A; Abayomi, I O

1991-02-01

173

Unilateral molar distalization: a nonextraction therapy.  

PubMed

In the recent years, nonextraction treatment approaches and noncompliance therapies have become more popular in the correction of space discrepancies. One of the conventional approaches for space gaining in the arches without patient compliance is done by using certain extra oral appliances or intraoral appliance. The greatest advantage of certain appliances like fixed functional and molar distalization appliances is that they minimize the dependence on patient cooperation. Molar distalization appliances like pendulum appliance which distalizes the molar rapidly without the need of head gear can be used in patients as a unilateral space gaining procedure due to buccal segment crowding. PMID:23320203

Prasad, M Bhanu; Sreevalli, S

2012-01-01

174

Unilateral Molar Distalization: A Nonextraction Therapy  

PubMed Central

In the recent years, nonextraction treatment approaches and noncompliance therapies have become more popular in the correction of space discrepancies. One of the conventional approaches for space gaining in the arches without patient compliance is done by using certain extra oral appliances or intraoral appliance. The greatest advantage of certain appliances like fixed functional and molar distalization appliances is that they minimize the dependence on patient cooperation. Molar distalization appliances like pendulum appliance which distalizes the molar rapidly without the need of head gear can be used in patients as a unilateral space gaining procedure due to buccal segment crowding.

Prasad, M. Bhanu; Sreevalli, S.

2012-01-01

175

Efficiency of molar distalization with the XBow appliance related to second molar eruption stage.  

PubMed

To quantitatively evaluate on lateral cephalograms horizontal, vertical, and angular changes in the position of the maxillary first molar based on the presence and absence of erupted maxillary second molars when it is distalized with the XBow appliance. In this retrospective study, a total of 102 consecutively treated cases were assessed. Lateral cephalograms were obtained at the start and after completion of active treatment with the XBow appliance. In one group of patients, distal movement of the maxillary first molars was performed before the eruption of maxillary second molars; in the other group of patients, both first and second maxillary molars were simultaneously moved distally. All cephalograms were superimposed on palatal plane using the method of best-fit. In order to compare the mean horizontal, vertical, and angular changes in molar position between the treatment groups and gender, a multivariate analysis of covariance (MANCOVA) was performed with the pre-treatment class II severity used as a covariate. Regression analysis was also performed to further explore any possible relationships between the predictor variables and the quantity and quality of distalization. A MANCOVA revealed that the eruption stage of the maxillary second molar did not have a significant effect on the change in position of the maxillary first molar after treatment with a XBow appliance. When distalizing maxillary first molars with a XBow appliance, there is no difference in the amount of distalization in patients with erupted and unerupted maxillary second molars. PMID:23172578

Flores-Mir, Carlos; McGrath, L M; Heo, G; Major, P W

2013-12-01

176

Fabrication and Evaluation of a Noncompliant Molar Distalizing Appliance: Bonded Molar Distalizer  

PubMed Central

Objective Attempts to treat class II malocclusions without extraction in non-compliant patients have led to utilization of intraoral molar distalizing appliances. The purpose of this study was to investigate dental and skeletal effects of Bonded Molar Distalizer (BMD) which is a simple molar distalizing appliance. Materials and Methods Sixteen patients (12 girls, four boys) with bilateral half-cusp class II molar relationship, erupted permanent second molars and normal or vertical growth pattern were selected for bilateral distalization of maxillary molars via BMD. The screws were activated every other day, alternately. Lateral cephalograms and study models were obtained before treatment and after 11 weeks activation of the appliance. Results Significant amounts of molar distalization, molar distal tipping and anchorage loss were observed. The mean maxillary first molar distal movement was 1.22±0.936 mm with a distal tipping of 2.97±3.74 degrees in 11 weeks. The rate of distal movement was 0.48 mm per month. Reciprocal mesial movement of the first premolars was 2.26±1.12 mm with a mesial tipping of 4.25±3.12 degrees. Maxillary incisors moved 3.55±1.46 mm and tipped 9.87±5.03 degrees mesially. Lower anterior face height (LAFH) decreased 1.28±1.36 mm. Conclusion BMD is appropriate for distalizing maxillary molars, especially in patients with critical LAFH, although significant amounts of anchorage loss occur using this appliance.

Sodagar, A.; Ahmad Akhoundi, M. S.; Rafighii, A.; Arab, S.

2011-01-01

177

Impact of partial volume effect correction on cerebral ?-amyloid imaging in APP-Swe mice using [(18)F]-florbetaben PET.  

PubMed

We previously investigated the progression of ?-amyloid deposition in brain of mice over-expressing amyloid-precursor protein (APP-Swe), a model of Alzheimer's disease (AD), in a longitudinal PET study with the novel ?-amyloid tracer [(18)F]-florbetaben. There were certain discrepancies between PET and autoradiographic findings, which seemed to arise from partial volume effects (PVE). Since this phenomenon can lead to bias, most especially in the quantitation of brain microPET studies of mice, we aimed in the present study to investigate the magnitude of PVE on [(18)F]-florbetaben quantitation in murine brain, and to establish and validate a useful correction method (PVEC). Phantom studies with solutions of known radioactivity concentration were performed to measure the full-width-at-half-maximum (FWHM) resolution of the Siemens Inveon DPET and to validate a volume-of-interest (VOI)-based PVEC algorithm. Several VOI-brain-masks were applied to perform in vivo PVEC on [(18)F]-florbetaben data from C57BL/6(N=6) mice, while uncorrected and PVE-corrected data were cross-validated with gamma counting and autoradiography. Next, PVEC was performed on longitudinal PET data set consisting of 43 PET scans in APP-Swe (13-20months) and age-matched wild-type (WT) mice using the previously defined masks. VOI-based cortex-to-cerebellum ratios (SUVR) were compared for uncorrected and PVE-corrected results. Brains from a subset of transgenic mice were ultimately examined by autoradiography ex vivo and histochemistry in vitro as gold standard assessments, and compared to VOI-based PET results. The phantom study indicated a FWHM of 1.72mm. Applying a VOI-brain-mask including extracerebral regions gave robust PVEC, with increased precision of the SUVR results. Cortical SUVR increased with age in APP-Swe mice compared to baseline measurements (16months: +5.5%, p<0.005; 20months: +15.5%, p<0.05) with uncorrected data, and to a substantially greater extent with PVEC (16months: +12.2% p<0.005; 20months: +36.4% p<0.05). WT animals showed no binding changes, irrespective of PVEC. Relative to autoradiographic results, the error [%] for uncorrected cortical SUVR was 18.9% for native PET data, and declined to 4.8% upon PVEC, in high correlation with histochemistry results. We calculate that PVEC increases by 10% statistical power for detecting altered [(18)F]-florbetaben uptake in aging APP-Swe mice in planned studies of disease modifying treatments on amyloidogenesis. PMID:24055703

Brendel, Matthias; Delker, Andreas; Rötzer, Christina; Böning, Guido; Carlsen, Janette; Cyran, Clemens; Mille, Erik; Gildehaus, Franz Josef; Cumming, Paul; Baumann, Karlheinz; Steiner, Harald; Haass, Christian; Herms, Jochen; Bartenstein, Peter; Rominger, Axel

2014-01-01

178

Can a partial volume edge effect reduction algorithm improve the repeatability of subject-specific finite element models of femurs obtained from CT data?  

PubMed

The reliability of patient-specific finite element (FE) modelling is dependent on the ability to provide repeatable analyses. Differences of inter-operator generated grids can produce variability in strain and stress readings at a desired location, which are magnified at the surface of the model as a result of the partial volume edge effects (PVEEs). In this study, a new approach is introduced based on an in-house developed algorithm which adjusts the location of the model's surface nodes to a consistent predefined threshold Hounsfield unit value. Three cadaveric human femora specimens were CT scanned, and surface models were created after a semi-automatic segmentation by three different experienced operators. A FE analysis was conducted for each model, with and without applying the surface-adjustment algorithm (a total of 18 models), implementing identical boundary conditions. Maximum principal strain and stress and spatial coordinates were probed at six equivalent surface nodes from the six generated models for each of the three specimens at locations commonly utilised for experimental strain guage measurement validation. A Wilcoxon signed-ranks test was conducted to determine inter-operator variability and the impact of the PVEE-adjustment algorithm. The average inter-operator difference in stress values was significantly reduced after applying the adjustment algorithm (before: 3.32 ± 4.35 MPa, after: 1.47 ± 1.77 MPa, p = 0.025). Strain values were found to be less sensitive to inter-operative variability (p = 0.286). In summary, the new approach as presented in this study may provide a means to improve the repeatability of subject-specific FE models of bone obtained from CT data. PMID:22452517

Peleg, Eran; Herblum, Ryan; Beek, Maarten; Joskowicz, Leo; Liebergall, Meir; Mosheiff, Rami; Whyne, Cari

2014-01-01

179

Maintaining perspective on third molar extraction.  

PubMed

Third molar extraction is one of the most common oral surgeries performed on Canadian patients, particularly young adults. Vigorous debate persists about the risks of retention of asymptomatic impacted third molars, compared to extraction. The controversy centres on whether medical necessity justifies the cost of third molar extraction for the patient in terms of substantial pain and potential loss of income during recovery and for the federal or provincial health care systems, which may be billed for a portion of the surgical fees. Several research studies initiated by the American Association of Oral and Maxillofacial Surgeons (AAOMS) report new associations between oral disease and asymptomatic impacted third molars. These findings merit careful attention because they are being used by the AAOMS to advocate for prophylactic third molar extraction-an approach that contradicts the conclusions of a Canadian health technology report, American Public Health Association policy, and health technology reports from Sweden, Belgium and the UK. The decision to extract third molars seems most effective when made on a case-by-case basis that is tailored to each patient's health status and access to professional oral health care. PMID:24309037

Boughner, Julia C

2013-09-01

180

Influence of the partial volume correction method on (18)F-fluorodeoxyglucose brain kinetic modelling from dynamic PET images reconstructed with resolution model based OSEM.  

PubMed

Kinetic parameters estimated from dynamic (18)F-fluorodeoxyglucose ((18)F-FDG) PET acquisitions have been used frequently to assess brain function in humans. Neglecting partial volume correction (PVC) for a dynamic series has been shown to produce significant bias in model estimates. Accurate PVC requires a space-variant model describing the reconstructed image spatial point spread function (PSF) that accounts for resolution limitations, including non-uniformities across the field of view due to the parallax effect. For ordered subsets expectation maximization (OSEM), image resolution convergence is local and influenced significantly by the number of iterations, the count density, and background-to-target ratio. As both count density and background-to-target values for a brain structure can change during a dynamic scan, the local image resolution may also concurrently vary. When PVC is applied post-reconstruction the kinetic parameter estimates may be biased when neglecting the frame-dependent resolution. We explored the influence of the PVC method and implementation on kinetic parameters estimated by fitting (18)F-FDG dynamic data acquired on a dedicated brain PET scanner and reconstructed with and without PSF modelling in the OSEM algorithm. The performance of several PVC algorithms was quantified with a phantom experiment, an anthropomorphic Monte Carlo simulation, and a patient scan. Using the last frame reconstructed image only for regional spread function (RSF) generation, as opposed to computing RSFs for each frame independently, and applying perturbation geometric transfer matrix PVC with PSF based OSEM produced the lowest magnitude bias kinetic parameter estimates in most instances, although at the cost of increased noise compared to the PVC methods utilizing conventional OSEM. Use of the last frame RSFs for PVC with no PSF modelling in the OSEM algorithm produced the lowest bias in cerebral metabolic rate of glucose estimates, although by less than 5% in most cases compared to the other PVC methods. The results indicate that the PVC implementation and choice of PSF modelling in the reconstruction can significantly impact model parameters. PMID:24052021

Bowen, Spencer L; Byars, Larry G; Michel, Christian J; Chonde, Daniel B; Catana, Ciprian

2013-10-21

181

Influence of the partial volume correction method on 18F-fluorodeoxyglucose brain kinetic modelling from dynamic PET images reconstructed with resolution model based OSEM  

NASA Astrophysics Data System (ADS)

Kinetic parameters estimated from dynamic 18F-fluorodeoxyglucose (18F-FDG) PET acquisitions have been used frequently to assess brain function in humans. Neglecting partial volume correction (PVC) for a dynamic series has been shown to produce significant bias in model estimates. Accurate PVC requires a space-variant model describing the reconstructed image spatial point spread function (PSF) that accounts for resolution limitations, including non-uniformities across the field of view due to the parallax effect. For ordered subsets expectation maximization (OSEM), image resolution convergence is local and influenced significantly by the number of iterations, the count density, and background-to-target ratio. As both count density and background-to-target values for a brain structure can change during a dynamic scan, the local image resolution may also concurrently vary. When PVC is applied post-reconstruction the kinetic parameter estimates may be biased when neglecting the frame-dependent resolution. We explored the influence of the PVC method and implementation on kinetic parameters estimated by fitting 18F-FDG dynamic data acquired on a dedicated brain PET scanner and reconstructed with and without PSF modelling in the OSEM algorithm. The performance of several PVC algorithms was quantified with a phantom experiment, an anthropomorphic Monte Carlo simulation, and a patient scan. Using the last frame reconstructed image only for regional spread function (RSF) generation, as opposed to computing RSFs for each frame independently, and applying perturbation geometric transfer matrix PVC with PSF based OSEM produced the lowest magnitude bias kinetic parameter estimates in most instances, although at the cost of increased noise compared to the PVC methods utilizing conventional OSEM. Use of the last frame RSFs for PVC with no PSF modelling in the OSEM algorithm produced the lowest bias in cerebral metabolic rate of glucose estimates, although by less than 5% in most cases compared to the other PVC methods. The results indicate that the PVC implementation and choice of PSF modelling in the reconstruction can significantly impact model parameters.

Bowen, Spencer L.; Byars, Larry G.; Michel, Christian J.; Chonde, Daniel B.; Catana, Ciprian

2013-10-01

182

A new approach in maxillary molar distalization: Intraoral bodily molar distalizer  

Microsoft Academic Search

The objectives of our study were to achieve bodily molar distalization, avoid distal tipping of molars, eliminate the need for patient cooperation (no headgear, no elastics, and no esthetic and social concern), and finally to minimize the treatment period and maximize the treatment efficiency. The study was carried out on 5 males and 10 females, a total of 15 patients.

Ahmet Keles; Korkmaz Sayinsu

2000-01-01

183

The partial molal volume of silicic acid in 0.725 M NaCl at 1°C determined by the neutralization of Na 2SiO 3  

NASA Astrophysics Data System (ADS)

The partial molal volume of silicic acid ( V¯(Si(OH) 4) ) in 0.725 M NaCl at 1°C was calculated from the measured volume change (? V¯n) due to the neutralization of anhydrous sodium metasilicate with HCl and the V¯(HCl) and V¯(NaCl) obtained from the literature. V¯(Si(OH) 4) = 59.0 cm 3mol - 1 , determined under experimental conditions of pH = 2.2, compares favorably with V¯(Si(OH) 4) = 58.9 cm 3 mol -1 calculated from the measured volume change due to the hydrolysis of the meta-silicate salt at pH = 11 and from the partial molal volume due to electrostriction ( V¯elect) of water by charged Si species present in the solution at the high pH. This agreement lends support to a semiempirical model for calculating V¯elect in developed by Millero (1969). V¯(NaOH) = - 5.45 cm 3 mol -1 in 0.725 M NaCl needed for this calculation was also determined in this work. The rate of polymerization of Si(OH) 4 at 1°C was monitored to insure that the monomer Si(OH) 4 was the main Si species present during the determination of V¯(Si(OH) 4) by neutralization of the alkali silicate. V¯(Si(OH) 4) determined in this study compares favorably with the value calculated from high pressure solubility measurements.

Hershey, J. Peter; Duedall, Iver W.

1983-11-01

184

Partial listing of coal waste embankments, surface and underground openings: appendix, volume II. Open file report (final) Mar 80-Aug 81  

SciTech Connect

Volume 3 of this three-volume report contains brief descriptions of the terms and codes used for each of the inventoried sites in Mining Safety and Health Administration districts 3, 4, 5, and 6. Detailed site mapping and the disposal site characterization forms for districts 5 and 6 are included.

Ahnell, G.; Hervol, J.D.; Mentz, J.W.; McClure, R.E.; Reed, T.L.

1982-02-01

185

Partial listing of coal waste embankments, surface and underground openings: appendix, volume I. Open file report (final) Mar 80-Aug 81  

SciTech Connect

Volume 2 of this three-volume report contains brief descriptions of the terms and codes used for each of the inventoried sites in Mining Safety and Health Administration districts 3, 4, 5, and 6. Detailed site mapping and the disposal site characterization forms for districts 3 and 4 are included.

Ahnell, G.; Hervol, J.D.; Mentz, J.W.; McClure, R.E.; Reed, T.L.

1982-02-01

186

Thyroid storm caused by a partial hydatidiform mole.  

PubMed

Clinical thyrotoxicosis is rare in molar pregnancy and has yet to be reported in a patient with a partial mole. Human chorionic gonadotropin (hCG), which has thyrotropic activity, is believed to be responsible for hyperthyroidism of gestational trophoblastic activity and hyperemesis gravidarum. We report the first case of hyperthyroidism presenting as thyroid storm in a partial molar pregnancy. Normal thyroid function returned after the partial mole was evacuated, and the biochemical improvement correlated with declining hCG levels. This case highlights the importance of including partial mole in the differential of hCG-mediated hyperthyroidism. PMID:18352822

Chiniwala, Niyati U; Woolf, Paul D; Bruno, Christopher P; Kaur, Sukhjinder; Spector, Harvey; Yacono, Kelli

2008-04-01

187

Clostridium perfringens sepsis following a molar pregnancy.  

PubMed

Clostridium perfringens sepsis is rare since the legalization of abortion in 1973. This is a 49 year old female who developed clostridial sepsis after suction dilation and curettage for a molar pregnancy. A hysterectomy was performed after prompt recognition, and the patient survived. PMID:24096275

Adams, Brandi N; Lekovic, Jovana P; Robinson, Suzzette

2014-01-01

188

Pathological (late) fractures of the mandibular angle after lower third molar removal: a case series  

PubMed Central

Introduction Pathological (late) fracture of the mandibular angle after third molar surgery is very rare (0.005% of third molar removals). There are 94 cases reported in the literature; cases associated with osseous pathologies such as osteomyelitis or any local and systemic diseases that may compromise mandibular bone strength have not been included. We describe three new cases of pathological (late) fracture of the mandibular angle after third molar surgery. Case presentations The first patient was a 27-year-old Caucasian man who had undergone surgical removal of a 3.8, mesioangular variety, class II-C third molar 20 days before admission to our clinic. The fracture of his left mandibular angle, complete and composed, occurred during chewing. The second patient was a 32-year-old Caucasian man. He had undergone surgical removal of a 3.8, mesioangular variety, class II-B third molar 22 days before his admission. The fracture, which occurred during mastication, was studied by computed tomography that showed reparative tissue in the fracture site. The third patient was a 36-year-old Caucasian man who had undergone surgical removal of a 3.8, vertical variety, class II-C third molar 25 days before the observation. In this case the fracture of his mandibular angle was oblique (unfavorable), complete and composed. The fracture had occurred during chewing. We studied the fracture by optical projection tomography and computed tomography. All of the surgical removals of the 3.8 third molars, performed by the patients’ dentists who had more than 10 years of experience, were difficult. We treated the fractures with open surgical reduction, internal fixation by titanium miniplates and intermaxillary elastic fixation removed after 6 weeks. Conclusions The literature indicates that the risk of pathological (late) fracture of the mandibular angle after third molar surgery for total inclusions (class II-III, type C) is twice that of partial inclusions due to the necessity of ostectomies more generous than those for partial inclusions. Other important factors are the anatomy of the teeth and the features of the teeth roots. These fractures predominantly occur in patients who are older than 25 years. The highest incidence (67.8% of cases) is found in the second and third week postsurgery. We emphasize that before the third molar surgery it is extremely important to always provide adequate instructions to the patient in order to avoid early masticatory loads and prevent this rare event.

2013-01-01

189

Value of Computed Tomography (CT) in Imaging the Morbidity of Submerged Molars: A Case Report  

PubMed Central

Submerged primary molars can be difficult to manage due to the developing dentition. Rarely in some severe cases, may the surgical interventions be required while ensuring the vital structures are protected. Therefore these cases require sophisticated imaging techniques in order to locate the vital structures. In this case report, a 17 year old girl who had a retained and submerged deciduous molar which caused impaction of the second premolar and tipping of the first molar was presented. In addition, value of computed tomography (CT) for locating the vital anatomic structures was discussed. In our case, CT has been supplied effective information about localization of the vital structures and amount of bone volume during the diagnosis and treatment planning period in addition to the routine dental radiographies.

K?rz?oglu, Zuhal; Karay?lmaz, Huseyin; Baykal, Bahattin

2007-01-01

190

Cell ploidy in molar placental disease.  

PubMed

Molar diseases of the placenta is associated with cystic change in the villi. The cysts may be from 5-20+ mm in diameter. This disease has been described in association with triploid and diploid cell lines and with and without an accompanying embryo or fetus. It may be followed by malignant change and invasive chorio-carcinoma. In order to investigate the association between cell ploidy, embryonic development and subsequent malignancy, a detailed study of 30 conceptuses with molar disease was made, with the accompanying maternal history and follow-up. The cell ploidy was determined by measurement of nuclei by a cytoscan light microscope connected to a computer program as has been previously described. Diploid cell lines were not found with embryonic or fetal development. Triploid cell lines were always associated with an embryo or fetus. Triploidy is not associated with hyperplastic changes in the trophoblast. These results are presented and discussed. PMID:715729

Poland, B J; Baillie, D L

1978-10-01

191

Mineral trioxide aggregate in primary molar pulpotomies  

Microsoft Academic Search

DesignQuasi-randomised controlled trial.InterventionPrimary molar teeth were treated using a conventional pulpotomy technique but received either mineral trioxide aggregate (MTA, test group) or formocresol (FC, control group) as a pulp dressing. Follow-up clinical (not blind) and radiographic (blind) assessments were undertaken every 6 months.Outcome measureTime elapsed between treatment and either 1) detection of pulpotomy failure 2) natural exfoliation of tooth 3)

Monty Duggal; Mohammed Al Ansary

2006-01-01

192

An analysis of molar tooth form  

Microsoft Academic Search

The maxillary first permanent molars of different human population samples were compared by multivariate analysis of two-dimensional coordinates of datum points defining the occlusal surface and periphery of the crown. This technique proved that discrimination was possible between teeth which could not be discriminated visually or by analysis of the mesio-distal or buccolingual diameters.Copyright © 1978 S. Karger AG, Basel

C. L. B. Lavelle

1978-01-01

193

Etiological factors in second mandibular molar impaction  

PubMed Central

Objectives: The impaction of the second mandibular molar (MM2) has recently become more prevalent. Several etiological hypothesis have been proposed to investigate the association between skeletal features and impaction of MM2. The aims of this study were to analyze the skeletal features in patients with MM2 impaction and the association between arrested eruption of MM2 and the presence of the third mandibular molar (MM3). Study Design: In this retrospective study 48 subjects from 3,530 Caucasian orthodontic patients with MM2 impaction were included in a study group (SG) and compared to a control group (CG) of 200 subjects without MM2 impaction. Panoramic radiographs evaluated the presence or absence of the MM3 germ. Cephalometric analysis was performed to evaluate linear and angular skeletal values. For the statistical analysis, descriptive statistics, Student’s t-test, ?2 test and odds ratio (OR) were used. Results: The paired comparisons between SG and CG showed in cephalometric analysis both a reduced mandibular gonial angle (ArGoMe) and lowered Jarabak’s polygon value with a statistically significant difference (P? 0.05). MM3 was statistically significant associated (P? 0.05) with MM2 impaction but it is not a risk factor (OR 0.817). Conclusions: Subjects with MM2 impaction show a vertical condylar growth direction. MM3 is not a risk factor for MM2 impaction. Key words:Impacted mandibular second molar, skeletal features, orthodontic.

Altieri, Federica; Calasso, Sabrina

2014-01-01

194

Third Molars and Acute Pericoronitis: A Military Problem.  

National Technical Information Service (NTIS)

Acute pericoronitis is a debilitating disease that primarily afflicts the soft and bony tissues of third molars in young adults. The positional characteristics of the third molars and the prevalence of acute pericoronitis at the time of entry is described...

S. A. Leone M. J. Edenfield

1987-01-01

195

Molar Tooth Diversity, Disparity, and Ecology in Cenozoic Ungulate Radiations  

Microsoft Academic Search

A classic example of adaptive radiation is the diversification of Cenozoic ungulates into herbivore adaptive zones. Their taxonomic diversification has been associated with changes in molar tooth morphology. Analysis of molar crown types of the Artiodactyla, Perissodactyla, and archaic ungulates (\\

Jukka Jernvall; John P. Hunter; Mikael Fortelius

1996-01-01

196

A comparative study on the volume and localization of the internal gross target volume defined using the seroma and surgical clips based on 4DCT scan for external-beam partial breast irradiation after breast conserving surgery  

PubMed Central

Background To explore the volume and localization of the internal gross target volume defined using the seroma and/or surgical clips based on the four-dimensional computed tomography (4DCT) during free-breathing. Methods Fifteen breast cancer patients after breast-conserving surgery (BCS) were recruited for EB-PBI. On the ten sets CT images, the gross target volume formed by the clips, the seroma, both the clips and seroma delineated by one radiation oncologist and defined as GTVc, GTVs and GTVc?+?s, respectively. The ten GTVc, GTVs and GTVc?+?s on the ten sets CT images produced the IGTVc, IGTVs, IGTVc?+?s, respectively. The IGTV volume and the distance between the center of IGTVc, IGTVs, IGTVc?+?s were all recorded. Conformity index (CI), degree of inclusion (DI) were calculated for IGTV/IGTV, respectively. Results The volume of IGTVc?+?s were significantly larger than the IGTVc and IGTVs (p?volume difference and spatial mismatch between the IGTVs delineated based on the surgical clips and seroma. The IGTV defined as the seroma and surgical clips provided the best overall representation of the ‘true’ moving GTV.

2014-01-01

197

Distal molar movement with Kloehn headgear: Is it stable?  

Microsoft Academic Search

The aim of this study was to evaluate intramaxillary molar movement after 8 months of cervical traction and posttreatment displacement 7 years later. The total molar displacements in relation to stable intraosseous reference points were compared with those observed in an untreated control group that also had intraosseous reference indicators inserted. During the headgear period, the type of molar displacement

Birte Melsen; Michel Dalstra

2003-01-01

198

Influence of eruption stage and biofilm accumulation on occlusal caries in permanent molars: a generalized estimating equations logistic approach.  

PubMed

The aim of this study was to estimate the independent effects of biofilm accumulation and eruption stage on the occurrence of active caries lesions on occlusal surfaces of permanent molars. The sample consisted of 298 schoolchildren (6-15 years) who were examined by a calibrated examiner at a dental unit, using artificial light, a dental mirror and a WHO probe. The occurrence of visible biofilm on occlusal surfaces and the eruption stage of each permanent molar were recorded. After professional prophylaxis and air drying, the occlusal surfaces were classified as sound, caries-inactive or caries-active. To evaluate the association of eruption stage and biofilm accumulation with active caries lesions, a logistic regression model was used. Since data were clustered, odds ratios were obtained using generalized estimating equations with a logistic link function. 1,779 permanent molars were examined. All eruption stages were associated with active caries lesions. After adjustment for biofilm accumulation and type of molar, molars with occlusal surfaces partially exposed to the oral cavity were 63.6 times more susceptible to caries activity than molars with full occlusion (95% CI = 22.0-183.7). After adjustment for eruption stage and type of molar, teeth with a high degree of biofilm accumulation were 14.5 times more susceptible to caries activity than those without visible biofilm accumulation (95% CI = 6.5-32.4). No association between active caries and hardly detectable biofilm was found in this population. The present study found that the eruption stage of permanent molars is strongly associated with active caries lesions, adjusted for biofilm accumulation and type of molar. PMID:23221986

Zenkner, J E A; Alves, L S; de Oliveira, R S; Bica, R H; Wagner, M B; Maltz, M

2013-01-01

199

LANDSAT-D data format control book. Volume 6, appendix A: Partially processed thematic mapper High Density Tape (HDT-AT)  

NASA Technical Reports Server (NTRS)

One of the outputs of the data management system being developed to provide a variety of standard image products from the thematic mapper and the multispectral band scanners on LANDSAT 4, is the partially processed TM data (radiometric corrections applied and geometric correction matrices for two projections appended) which is recorded on a 28-track high density tape. Specifications are presented for the format of the recorded data as well as for the time code and the major and minor frames of the tape. Major frame types, formats, and field definitions are included.

Jai, A.

1982-01-01

200

Natal primary molar: clinical and histological aspects.  

PubMed

The authors report a case of natal primary molar in a healthy 14-day-old child. The diagnosis of the case and the treatment plan are discussed, as well as histological analyses of the natal tooth. The tooth presented an immature appearance, with high mobility and insertion only in soft tissue, and therefore the clinical option adopted was dental extraction. Histological analyses revealed enamel hypoplasia and dentin showing a typical tubular pattern without alterations. The soft tissue had young and richly vascularized pulp with areas of chronic inflammatory infiltration. PMID:20587958

Ruschel, Henrique C; Spiguel, Monica H; Piccinini, Daniela D; Ferreira, Simone H; Feldens, Eliane G

2010-06-01

201

Topographic study of root trunk type on Chinese molars with Class III furcation involvements: molar type and furcation site.  

PubMed

This study investigated the relationship between root trunk length and prognosis for molars with furcation involvement. Molars with furcation involvement were obtained from 169 patients affected with periodontitis. The test group consisted of 174 hopeless molars screened from a total of 441 molars with Class III involvement; the remaining 267 molars formed the control group. Both arches showed a significantly higher missing rate for teeth with a long root trunk length (type C) in second molars (41.3% and 32.4% in the maxilla and mandible, respectively), with a high degree of Class III furcation involvement for the test group (extracted hopeless or poor prognosis), compared to first molars (9.9% and 0.9% in the maxilla and mandible, respectively). Both arches had a significantly higher prevalence of long root trunk lengths in the second molars compared to first molars, irrespective of furcation site. Although first molars had an early and higher prevalence of Class III furcation involvement than second molars, the latter reached a significantly higher missing rate. Molars with longer root trunk lengths had a higher risk for poor prognosis than shorter root trunks when teeth were affected by Class III furcation involvement. For extracted furcation-involved maxillary second molars that failed to respond to periodontal therapy, long root trunk length (C) accounted for the greatest prevalence at the mesial furcation site (41.8%), followed by the distal (33.0%) and buccal sites (25.2%); the greatest prevalence of root trunk length C was found at the lingual (47.9%) and buccal furcation sites (45.1%) of mandibular second molars. When a molar with root trunk type C has a Class III involvement, the prognosis is poor; for the disease to reach that level, greater amounts of attachment must be destroyed. PMID:15839594

Hou, Guey-Lin; Hung, Chun-Cheng; Tsai, Chi-Cheng; Weisgold, Amold S

2005-04-01

202

High-rate partial nitritation using porous poly(vinyl alcohol) sponge.  

PubMed

Poly(vinyl alcohol) (PVA) has been utilized as a support material for the immobilization of nitrifying bacteria without the comprehensive survey of partial nitritation. In the present study, the activities of nitrifiers and the maximum nitrogen conversion rate of partial nitritation with PVA sponge-cubes were specified according to different conditions. The selective enrichment of ammonia-oxidizing bacteria (AOB) on PVA sponge-cubes was achieved by the competition between AOB and nitrite-oxidizing bacteria for dissolved oxygen. The efficiency of ammonia oxidation was proportional to the concentration of HCO3 (-) with the molar ratio of HCO3 (-)-C/NH4 (+)-N = 1.91 and a half of the ratio was applied to the further experiments to ensure stable partial nitritation. The maximum nitrogen conversion rate of partial nitritation was dependent on the volume, not the size of sponge-cubes. The partial nitritation showed the superior rate performance of 3.09 kg N/m(3) day with the packing ratio of 32 % of 5 × 5 × 5 mm(3) PVA sponge-cubes. PMID:24297159

Bae, Hyokwan; Yang, Heejeong; Chung, Yun-Chul; Yoo, Young Je; Lee, Seockheon

2014-06-01

203

Onset of molar incisor hypomineralization (MIH).  

PubMed

The etiological factors and timing of the onset of molar incisor hypomineralization (MIH) are still not clear. The aim of this study was to examine ground radial and sagittal sections from teeth diagnosed with MIH using light microscopy, polarized light microscopy and X-ray micro-computed tomography (XMCT) and to estimate the onset and timing of the MIH and to relate the hypomineralized enamel to the incremental lines. Thirteen extracted permanent first molars diagnosed MIH, were analyzed with light microscopy and XMCT. The hypomineralized areas were mainly located in the mesio-buccal cusps, starting at the enamel-dentin-junction and continuing towards the enamel surface. In a relative gray scale analysis the values decreased from the EDJ towards the enamel surface. The findings indicate that the ameloblasts in the hypomineralized enamel are capable of forming an enamel of normal thickness, but with a substantial reduction of their capacity for maturation of enamel. Chronologically, it is estimated that the timing of the disturbance is at a period during the first 6-7 months of age. PMID:23957140

Fagrell, Tobias G; Salmon, Phil; Melin, Lisa; Norén, Jörgen G

2013-01-01

204

Oxygen stoichiometry, unit cell volume, and thermodynamic quantities of perovskite-type oxides  

Microsoft Academic Search

Perovskite-type oxides $${\\\\text{A}}_{{{\\\\text{1 - }}a}} {\\\\text{A}}^{\\\\prime }_{{\\\\text{a}}} {\\\\text{B}}_{{{\\\\text{1 - }}b}} {\\\\text{B}}^{\\\\prime }_{{\\\\text{b}}} {\\\\text{O}}_{{{\\\\text{3 - }}x}}$$ with A, A?=La, Ba, Sr; B, B?=Mn, Fe, Co were investigated by means of thermal analysis, solid electrolyte cells, and X-ray\\u000a diffraction. Partial molar thermodynamic quantities are determined and their relations with O\\/M stoichiometry, unit cell volume,\\u000a and phase stability were studied. The absolute values

Egle Girdauskaite; Helmut Ullmann; Mahmoud Al Daroukh; Vladimir Vashook; Martin Bülow; Ulrich Guth

2007-01-01

205

Partial liver transplantation.  

PubMed

Partial liver transplantation, including reducedsize liver transplantation, split liver transplantation, and living donor liver transplantation, has been developed with several innovative techniques because of donor shortage. Reduced-size liver transplantation is based on Couinaud's anatomical classification, benefiting children and small adult recipients but failing to relieve the overall donor shortage. Split liver transplantation provides chances to two or even more recipients when only one liver graft is available. The splitting technique must follow stricter anatomical and physiological criteria either ex situ or in situ to ensure long-term quality. The first and most important issue involving living donor liver transplantation is donor safety. Before surgery, a series of donor evaluations-including anatomical, liver volume, and liver function evaluations-is indispensable, followed by ethnic agreement. At different recipient conditions, auxiliary liver transplantation and auxiliary partial orthotopic liver transplantation, which employ piggyback techniques, are good alternatives. Partial liver transplantation enriches the practice and knowledge of the transplant society. PMID:21681668

Gong, Nianqiao; Chen, Xiaoping

2011-03-01

206

Clinical significance of computed tomography assessment for third molar surgery  

PubMed Central

Surgical extraction of the third molar is the most commonly performed surgical procedure in the clinical practice of oral surgery. Third molar surgery is warranted when there is inadequate space for eruption, malpositioning, or risk for cyst or odontogenic tumor formation. Preoperative assessment should include a detailed morphologic analysis of the third molar and its relationship to adjacent structures and surrounding tissues. Due to developments in medical engineering technology, computed tomography (CT) now plays a critical role in providing the clear images required for adequate assessment prior to third molar surgery. Removal of the maxillary third molar is associated with a risk for maxillary sinus perforation, whereas removal of the mandibular third molar can put patients at risk for a neurosensory deficit from damage to the lingual nerve or inferior alveolar nerve. Multiple factors, including demographic, anatomic, and treatment-related factors, influence the incidence of nerve injury during or following removal of the third molar. CT assessment of the third molar prior to surgery can identify some of these risk factors, such as the absence of cortication between the mandibular third molar and the inferior alveolar canal, prior to surgery to reduce the risk for nerve damage. This topic highlight presents an overview of the clinical significance of CT assessment in third molar surgery.

Nakamori, Kenji; Tomihara, Kei; Noguchi, Makoto

2014-01-01

207

Lower dental arch changes after bilateral third molar removal.  

PubMed

OBJECTIVE. To evaluate the changes in lower dental arch after bilateral lower third molars removal. MATERIAL AND METHODS. The study group consisted of 30 non-orthodontic patients (mean age 25,5 years, refered for bilateral lower third molars removal. Orthopantomograms and dental casts were made before and 6-8 months after surgical removal of lower third molars. Transversal lower arch widths between lower canines and second premolars and lower arch total tooth size-arch lenght discrepancy were evaluated on dental casts. The angulation of lower second premolars, first and second molars was measured in horizontal and mandibular planes on orthopantomograms. RESULTS. No significant difference of inter-canine and inter-premolar transversal width was noticed. No significant changes were observed in total tooth-size lenght discrepancy, except in S1 segment consisted of first and second premolar and the canine on the right quadrant of the lower dental arch. The angulation of second premolars and first molars did not show any significant changes, however there were statistically significant changes between angulation of lower second molars on both sides. CONCLUSIONS. After bilateral removal of lower third molars, lower second molars awhile showed a tendency to move backwards, but no obvious relationship between the third molar and anterior crowding was observed. Whereas the observation time is short and the patient's age is young and it can not be concluded that lower third molars cause the changes in the dental arch. PMID:24824058

Stanaityt?, R?ta; Trakinien?, Giedr?; Gervickas, Albinas

2014-01-01

208

Electrical Insulating and Heat-Resistive Properties of PDMS-TEOS Hybrid with Different Molar Ratio of TEOS to PDMS  

Microsoft Academic Search

The hybrids prepared from polydimethylsiloxane (PDMS) and tetraethoxysilane (TEOS) have been well known to be rubbery hybrid materials. In this report, the authors have investigated the electrical insulating and heat resistive properties of the hybrids by changing the molar ratio of TEOS to PDMS. The electrical insulating properties are evaluated by volume resistivity and AC breakdown strength at room temperature.

Makoto Sugiura; Fumitoshi Imasato; Atsushi Ohno; Yusuke Aoki; Shuhei Nakamura; Tetsushi Okamoto; Takuya Shindou

2007-01-01

209

A simplified approach to true molar intrusion  

PubMed Central

Background Orthodontic management of anterior open bites is a demanding task for orthodontists. Molar intrusion as a primary means of open bite correction entails the need for appropriate anchorage. Orthodontic mini implants can provide the required mechanical support. The suggested procedure aims to reduce the risk of complications such as root damage or soft tissue irritations while minimizing overall complexity. Methods Three female patients aged 14, 18 and 19 years who decided against a surgical correction were treated with a device consisting of mini implants in the palatal slope, a palatal bar and intrusion cantilevers. Results In all three patients, an open bite reduction of more than a millimeter occurred within four months. An anterior overbite of 2 mm or more could be established within 6 to 9 months. Conclusions The method presented in this article enables the practitioner to use mini implants in an easily accessible insertion site. A lab-side procedure is optional but not required.

2012-01-01

210

Molar extinction coefficients of some fatty acids  

NASA Astrophysics Data System (ADS)

The attenuation of gamma rays in some fatty acids, viz. formic acid (CH 2O 2), acetic acid (C 2H 4O 2), propionic acid (C 3H 6O 2), butyric acid (C 4H 8O 2), n-hexanoic acid (C 6H 12O 2), n-caprylic acid (C 8H 16O 2), lauric acid (C 12H 24O 2), myristic acid (C 14H 28O 2), palmitic acid (C 16H 32O 2), oleic acid (C 18H 34O 2) and stearic acid (C 18H 36O 2), has been measured at the photon energies 81, 356, 511, 662, 1173 and 1332 keV. Experimental values for the molar extinction coefficient, the effective atomic number and the electron density have been derived and compared with theoretical calculations. There is good agreement between experiment and theory.

Sandhu, G. K.; Singh, Kulwant; Lark, B. S.; Gerward, L.

2002-10-01

211

Nerve damage and third molar removal.  

PubMed

The surgical removal of lower third molars endangers both the lingual and inferior alveolar nerves. Patients sustaining an injury to either of these nerves must be managed correctly, and this requires a diagnosis of the injury type and regular monitoring of the recovery of sensation. Surgical intervention for a damaged inferior alveolar nerve is not usually indicated but may be undertaken: if the nerve is completely divided and the severed ends are misaligned; if a bony fragment has compressed the mandibular canal; or if the patient suffers from persistent neuropathic pain. In contrast, after injury to the lingual nerve, if sensory testing demonstrates no neural recovery within 3-4 months, exploration of the injury site and microsurgical repair of the damaged nerve is indicated. PMID:14558203

Loescher, A R; Smith, K G; Robinson, P P

2003-09-01

212

Third molar surgery in general dental practice.  

PubMed

A survey to determine the treatment procedures adopted by general dental practitioners for the removal of impacted third molar teeth was undertaken. Questionnaires were mailed to a sample of 100 practising dentists. Of the 67 per cent that responded, 41.8 per cent (28) indicated that they would attempt the procedure while the remaining 51.2 per cent (39) would not do so. Neither the length of professional experience nor whether they practised in metropolitan or country areas had a bearing on whether the impacted tooth would be removed or not. In general, South African general dental practitioners routinely removed overlying bone by means of a bur, sutured the mucosal incision wound, prescribed antibiotics, analgesics and a mouthwash, and recalled their patients for a post-operative review. Steroids were not prescribed. PMID:9461920

Naidoo, L C

1997-02-01

213

Use of kilovoltage X-ray volume imaging in patient dose calculation for head-and-neck and partial brain radiation therapy  

PubMed Central

Background To evaluate the accuracy of using kilovoltage x-ray cone-beam computed tomography (kV-CBCT) imaging for in vivo dose calculations. Methods A Region-of-Interest (ROI) CT number mapping method was developed to generate the cone-beam CT number vs. relative electron density calibration curve for 3D dose calculations. The stability of the results was validated for three consecutive months. The method was evaluated on three brain tumors and three head-and-neck tumor cases. For each patient, kV-CBCT images were acquired on the first treatment day and two-week intervals on the Elekta XVI system. The delivered dose distributions were calculated by applying the patients' treatment plans to the kV-CBCT images. The resulting dose distributions and dose volume histograms (DVHs) of the tumor and critical structures were compared to the original treatment plan. Results The kV-CBCT electron density calibration was stable within 1.5% over a three-month period. The DVH and dose distribution comparison based on the planning CT and the initial kV-CBCT showed good agreements for majority of cases. The doses calculated from the planning CT and kV-CBCT were compared on planes perpendicular to the beam axes and passing through the isocenter. Using ? analysis with a criterion of 2 mm/2% and a threshold of 10%, more than 99.5% of the points on the iso-planes exhibited ? <1. For one patient, kV-CBCT images detected 5.8% dose variation in the right parotid due to tumor shrinkage and patient weight loss. Conclusions ROI mapping method is an effective method for the creation of kV-CBCT electron density calibration curves for head-and-neck and brain tumor patients. Dose variations as monitored using kV-CBCT imaging suggest that some patients can benefit from adaptive treatment plan re-optimization.

2010-01-01

214

Applications of tissue heterogeneity corrections and biologically effective dose volume histograms in assessing the doses for accelerated partial breast irradiation using an electronic brachytherapy source  

NASA Astrophysics Data System (ADS)

A low-energy electronic brachytherapy source (EBS), the model S700 Axxent™ x-ray device developed by Xoft Inc., has been used in high dose rate (HDR) intracavitary accelerated partial breast irradiation (APBI) as an alternative to an Ir-192 source. The prescription dose and delivery schema of the electronic brachytherapy APBI plan are the same as the Ir-192 plan. However, due to its lower mean energy than the Ir-192 source, an EBS plan has dosimetric and biological features different from an Ir-192 source plan. Current brachytherapy treatment planning methods may have large errors in treatment outcome prediction for an EBS plan. Two main factors contribute to the errors: the dosimetric influence of tissue heterogeneities and the enhancement of relative biological effectiveness (RBE) of electronic brachytherapy. This study quantified the effects of these two factors and revisited the plan quality of electronic brachytherapy APBI. The influence of tissue heterogeneities is studied by a Monte Carlo method and heterogeneous 'virtual patient' phantoms created from CT images and structure contours; the effect of RBE enhancement in the treatment outcome was estimated by biologically effective dose (BED) distribution. Ten electronic brachytherapy APBI cases were studied. The results showed that, for electronic brachytherapy cases, tissue heterogeneities and patient boundary effect decreased dose to the target and skin but increased dose to the bones. On average, the target dose coverage PTV V100 reduced from 95.0% in water phantoms (planned) to only 66.7% in virtual patient phantoms (actual). The actual maximum dose to the ribs is 3.3 times higher than the planned dose; the actual mean dose to the ipsilateral breast and maximum dose to the skin were reduced by 22% and 17%, respectively. Combining the effect of tissue heterogeneities and RBE enhancement, BED coverage of the target was 89.9% in virtual patient phantoms with RBE enhancement (actual BED) as compared to 95.2% in water phantoms without RBE enhancement (planned BED). About 10% increase in the source output is required to raise BED PTV V100 to 95%. As a conclusion, the composite effect of dose reduction in the target due to heterogeneities and RBE enhancement results in a net effect of 5.3% target BED coverage loss for electronic brachytherapy. Therefore, it is suggested that about 10% increase in the source output may be necessary to achieve sufficient target coverage higher than 95%.

Shi, Chengyu; Guo, Bingqi; Cheng, Chih-Yao; Eng, Tony; Papanikolaou, Nikos

2010-09-01

215

Epilepsy (partial)  

PubMed Central

Introduction About 3% of people will be diagnosed with epilepsy during their lifetime, but about 70% of people with epilepsy eventually go into remission. Methods and outcomes We conducted a systematic review and aimed to answer the following clinical questions: What are the effects of starting antiepileptic drug treatment following a single seizure? What are the effects of drug monotherapy in people with partial epilepsy? What are the effects of additional drug treatments in people with drug-resistant partial epilepsy? What is the risk of relapse in people in remission when withdrawing antiepileptic drugs? What are the effects of behavioural and psychological treatments for people with epilepsy? What are the effects of surgery in people with drug-resistant temporal lobe epilepsy? We searched: Medline, Embase, The Cochrane Library, and other important databases up to July 2009 (Clinical Evidence reviews are updated periodically; please check our website for the most up-to-date version of this review). We included harms alerts from relevant organisations such as the US Food and Drug Administration (FDA) and the UK Medicines and Healthcare products Regulatory Agency (MHRA). Results We found 83 systematic reviews, RCTs, or observational studies that met our inclusion criteria. We performed a GRADE evaluation of the quality of evidence for interventions. Conclusions In this systematic review we present information relating to the effectiveness and safety of the following interventions: antiepileptic drugs after a single seizure; monotherapy for partial epilepsy using carbamazepine, gabapentin, lamotrigine, levetiracetam, phenobarbital, phenytoin, sodium valproate, or topiramate; addition of second-line drugs for drug-resistant partial epilepsy (allopurinol, eslicarbazepine, gabapentin, lacosamide, lamotrigine, levetiracetam, losigamone, oxcarbazepine, retigabine, tiagabine, topiramate, vigabatrin, or zonisamide); antiepileptic drug withdrawal for people with partial or generalised epilepsy who are in remission; behavioural and psychological treatments for partial or generalised epilepsy (biofeedback, cognitive behavioural therapy (CBT), educational programmes, family counselling, relaxation therapy (alone or plus behavioural modification therapy, yoga); and surgery for drug-resistant temporal lobe epilepsy ( lesionectomy, temporal lobectomy, vagus nerve stimulation as adjunctive therapy).

2011-01-01

216

Congenitally missing maxillary first permanent molars: a case report.  

PubMed

Congenitally absent maxillary first permanent molars is a rare clinical finding. It usually occurs with severe oligodontia in association with other abnormalities of the integumentary system. This article presents the case of bilateral absent maxillary permanent molars with severe oligodontia and no other abnormalities. PMID:2369704

Lapeer, G L

1990-06-01

217

Growth and Calcification in the Prenatal Human Primary Molars  

Microsoft Academic Search

SYNOPSIS IN INTERLINGUA CRESCENTIA E CALCIFICATION IN LE PRENATAL MOLARES PRIMARI HUMAN.—Con le objectivo de studiar statisticamente le relation inter le crescentia e le calcification, le 4 germines de molares primari in 69 fetos human del gruppo de etate circumnatal esseva dissecate e tincturate con rubio alizarinic S. Le grado del calcification e le dimension microscopic del corona esseva determinate.

John W. Coughlin; Gordon J. Christensen

1966-01-01

218

Patients' Retrospective Preference for Extraction of Asymptomatic Third Molars.  

National Technical Information Service (NTIS)

The purpose of this study was to determine the personal utility of asymptomatic third molar removal in military patients. From 1 to 30 days (mean=7.4) after the extraction of one or more third molars, 100 returning patients (all male, mean age=20.1) were ...

J. S. Arthur J. W. Rodden M. E. Cohen

1990-01-01

219

Mandibular First Molar with a Single Root and Single Canal  

PubMed Central

Successful endodontic management of mandibular first molar with a single root and single canal is diagnosed with the aid of dental operating microscope and multiple angled radiographs. In addition all the mandibular molars and premolars were single rooted on either side.

Sooriaprakas, Chandrasekaran; Ballal, Suma; Velmurugan, Natanasabapathy

2014-01-01

220

Mandibular first molar with a single root and single canal.  

PubMed

Successful endodontic management of mandibular first molar with a single root and single canal is diagnosed with the aid of dental operating microscope and multiple angled radiographs. In addition all the mandibular molars and premolars were single rooted on either side. PMID:24715990

Sooriaprakas, Chandrasekaran; Ballal, Suma; Velmurugan, Natanasabapathy

2014-01-01

221

Infections in elderly patients associated with impacted third molars.  

PubMed

The objective of this study was to determine the clinical characteristics of infections caused by impacted third molars in elderly persons. Infectious disorders (26 pericoronitis, 8 secondarily infected dentigerous cysts, 4 perimandibular abscesses with limited osteomyelitis, 2 chronic mandibular osteomyelitis, and 1 odontogenic skin fistula) associated with the impacted third molars impacted third molars were clinically investigated in 41 patients over 60 years of age. Twenty-nine causative teeth were located in the mandibular angle and nine in the ramus; the three remaining lesions (two cysts one pericoronitis) were associated with the maxillary third molar. Bone resorption was noted in most patients, and this caused the originally embedded tooth to become exposed intraorally. It was concluded that oral infection in elder persons are occasionally caused by retained impacted third molars with overlapping of other factors. PMID:7614172

Osaki, T; Nomura, Y; Hirota, J; Yoneda, K

1995-02-01

222

Investigation of third molar impaction in Turkish orthodontic patients: Prevalence, depth and angular positions  

PubMed Central

Objective: We aimed to investigate the prevalence, distribution, angular position, and depth of third molar impaction in a Turkish orthodontic patient population. Materials and Methods: We retrospectively reviewed the panoramic radiographs, intraoral photographs, and dental casts of 207 patients (62 men and 145 women; age 20-39 years) who had undergone orthodontic treatment at a university department of orthodontics for impacted third molars (ITMs). A comprehensive chart review of all subjects was conducted. Patient and treatment-related data were recorded in a digital database for comparative analysis. Results: The prevalence of ITMs was 54.1%, and no statistically significant gender differences were evident (61.3% in men and 51.0% in women; P = 0.23). The frequency of maxillary ITMs was 49.3% (148 of 300 teeth) while that of mandibular ITMs was 50.7% (152 of 300 teeth). The most frequently observed angulations of impaction were mesioangular for the mandible (65.1%), and distoangular for the maxilla (64.2%). Of all the ITMs analysed, 61% were partially buried in bone and 39% were completely buried. Conclusions: Third molar impaction was evident in 54.1% of a group of Turkish orthodontic patients aged 20-39 years, and there was no statistically significant gender bias. Mesioangular and distoangular inclinations were the most common in the mandible and the maxilla, respectively.

Topkara, Ahu; Sari, Zafer

2013-01-01

223

Influence of third molars in Le Fort 1 osteotomy  

PubMed Central

Background: The influence of maxillary third molar (M3) on the outcomes of Le Fort 1 osteotomy is not deeply investigated. Aim: To investigate the influence of M3 on Le Fort 1 osteotomies. Setting: Tertiary Referral Center, operated by a single surgeon, prospective study. Period: January 2005 to December 2010. Patients: Consecutive Le Fort 1 osteotomy patients with both M3. Predictor Variable: Gender, position, M3 root morphology, and degree of impaction. Outcome Variable: Time taken after all osteotomy cuts to point of time when maxilla is placed in predetermined plane. Result: A total of 658 M3 in line of cut were studied. Of all M3, 312 were impacted, 28.9% were partially impacted and 23.7% were erupted. Of all the M3, 2.9% had their cuspal tips above the horizontal cut, 13.8% along the line of cut, and in 20.7% below the line but not erupted. Buccoverted tooth took shortest time (7.74 minutes), while palatoversion required more time (8.44 minutes) (P = 0.000). When the cuspal tip of M3 was located above the horizontal line of cut, the mean time required to achieve the planned position was 7 minutes, while the completely erupted teeth took a mean of 8.24 minutes (P = 0.000). Conclusion: When the M3 is placed higher, it takes lesser time to prepare basal bone to receive the maxilla at its predetermined level. Angulation of M3 influences the outcome. Deeply placed M3 reduces the manipulation of the greater pterygoid palatine vessels in the area thereby minimizing the bleeding in the surgical field.

Balaji, S. M.

2011-01-01

224

Human third molars development: Comparison of 9 country specific populations.  

PubMed

The majority of age estimation models based on third molar development are constructed on samples from populations with described and outlined origin. Due to unlike research protocols these studies can rarely be compared for the evaluation of possible geographical or ethnical influences on third molar development. The aim of this study is to evaluate country specific third molar development on standardized collected and analyzed data. On panoramic radiographs selected from subjects out of 9 country specific populations (Belgium, China, Japan, Korea, Poland, Thailand, Turkey, Saudi-Arabia and South-India) the four third molar scores were registered, according to a modified Gleiser and Hunt methodology. To obtain for each subject a (factor) score which represents the degree of third molar development, a generalized linear mixed model for multivariate ordinal data was fitted on the repeated third molar scores. Differences between countries are analyzed using gender-specific regression models for these factor scores with age and country as predictors. Comparisons between countries revealed differences in speed and onset of development. However, although reaching statistical significance, differences in actual value were small and not constant over the considered age range. In all countries, at all ages, males were ahead in third molar development compared to females. PMID:20570071

Thevissen, P W; Fieuws, S; Willems, G

2010-09-10

225

Maxillary molar distalization with a bone-anchored pendulum appliance.  

PubMed

To obtain an effective and compliance-free molar distalization without an anchorage loss, we designed the bone-anchored pendulum appliance (BAPA). The aim of this study was to evaluate the stability of the anchoring screw, distalization of the maxillary molars, and the movement of teeth anterior to maxillary first molars. The study group comprised 10 patients (mean age 13.5 +/- 1.8 years) with Class II molar relationship. A conventional pendulum appliance was modified to obtain anchorage from an intraosseous screw instead of the premolars. The screw was placed in the anterior paramedian region of the median palatal suture. Skeletal and dental changes were measured on cephalograms, and dental casts were obtained before and after distalization. A super Class I molar relationship was achieved in a mean period of 7.0 +/- 1.8 months. The maxillary first molars distalized an average of 6.4 +/- 1.3 mm in the region of the dental crown by tipping distally an average of 10.9 degrees +/- 2.8 degrees . Also, the maxillary second premolar and first premolar moved distally an average of 5.4 +/- 1.3 mm and 3.8 +/- 1.1 mm, respectively. The premolars tipped significantly distally. No anterior incisor movement was detected. The BAPA was found to be an effective, minimally invasive, and compliance-free intraoral distalization appliance for achieving both molar and premolar distalization without any anchorage loss. PMID:16808573

Kircelli, Beyza Hancio?lu; Pekta?, Zafer Ozgür; Kircelli, Cem

2006-07-01

226

Simple estimate of critical volume  

NASA Technical Reports Server (NTRS)

Method for estimating critical molar volume of materials is faster and simpler than previous procedures. Formula sums no more than 18 different contributions from components of chemical structure of material, and is as accurate (within 3 percent) as older more complicated models. Method should expedite many thermodynamic design calculations.

Fedors, R. F.

1980-01-01

227

Buckministerfullerene (C 60) encapsulated ground state atoms: semi-empirical approximate effective volume relations  

Microsoft Academic Search

An AM1 investigation of the molar volumes changes with values of Z for various atoms is investigated. Essentially all values for Z are decreasing according an exponential decay function for both cases of the complex atomic molar volumes, verses the molar radii computed (this is the so-called a0 value which is recommended radius which is 0.5Å larger than the radius

Abraham F. Jalbout; L. Türker

2003-01-01

228

Revascularization/Regeneration performed in immature molars: case reports.  

PubMed

These 3 case reports the outcome of revascularization treatment in necrotic immature molars. During treatment, a tri antibiotic mix was used to disinfect the pulp for 2 weeks. Then a blood clot was created in the canal, over which mineral trioxide aggregate was placed. After 24 months, the immature molars showed continuation of root development. The patients were asymptomatic, no sinus tracts were evident and apical periodontitis was resolved Results from these cases show that revascularization/regeneration using 3Mix-MP method could be effective for managing immature permanent molar teeth with pulpal necrosis. PMID:23855165

Sönmez, I S; Akbay Oba, A; Erkmen Almaz, M

2013-01-01

229

Molar heat capacity and entropy of calcium metal  

USGS Publications Warehouse

The heat capacity of calcium has been measured at 85 mean temperatures between T ??? 8 K and T ??? 369 K using an adiabatically-shielded calorimeter in an intermittent heating mode. At T = 298.15 K, the recommended values for the molar heat capacity, molar entropy, and molar enthalpy increment referred to T = 0 are (25.77 ?? 0.08) J??K-1??mol-1, (42.90 ?? 0.11) J??K-1??mol-1, and (5811 ?? 12) J??mol-1, respectively. The uncertainties are twice the standard deviation of the mean. ?? 1997 Academic Press Limited.

Hemingway, B. S.; Robie, R. A.; Chase, M. W.

1997-01-01

230

THE VOLUME OF DIMERIC BISMUTH MONOHALIDE DISSOLVED IN MOLTEN BISMUTH TRIHALIDE  

Microsoft Academic Search

The molar volume and apparent molar volume of a dimeric bismuth ; monohalide dissolved in a molten bismuth trihalide are calculated for bromide and ; chloride at 250 deg C and for iodide at 420 deg C for the mole fractions X\\/sub ; Bi2X2\\/ 0.039 and 0.177. (C.J.G.);

M. A. Bredig; H. A. Levy; F. J. Keneshea; D. Cubicciotti

1960-01-01

231

[Radiographic study of formation and calcification of the third molar].  

PubMed

A total of 500 orthopantomographic X-rays of Mexican children and teenagers of either sex, aged 7-18, were studied in order to ascertain the development and calcification stages of their third molars, as well as the most frequent anomalies related with them. It was observed that the dental bud appears between ages nine and eleven, and that the third molar is absent in 32.4% of the population, with a predominance of females over males. It was also found that 7.4% of molars evidenced malposition during their early stages of development. In view of such findings, the authors consider that a diagnosis of oligodontia and malposition of the third molar, cannot be established before age 13. PMID:2132460

Nuño González, M M; Llarena del Rosario, M E

1990-11-01

232

Molar extinction coefficient of fullerenes and related hydrogenated derivatives ``fulleranes''  

NASA Astrophysics Data System (ADS)

Fullerenes, the carbon molecules with 60 and 70 atoms, were recently detected in a series of planetary nebulae, in protoplanetary nebulae and in other astrophysical objects. The detection and the quantitative determination of these molecules was made possible by the measurement of their reference infrared spectra and the relative molar extinction coefficients and integrated molar absorptivity on laboratory scale. It is expected that also fulleranes the hydrogenated derivatives of C60 and C70 may be present in the same objects where fullerenes were detected. This prompted us to synthesize the hydrogenated fullerenes, to record their infrared spectra and the measure the molar extinction coefficients and integrated molar absorptivity on laboratory scale to have a reference in the search of these fullerene derivatives in space

Cataldo, Franco; Iglesias-Groth, Susana; Manchado, Arturo

2012-08-01

233

The Tucker technique: conservative molar inlays preserving the transverse ridge.  

PubMed

Conservation of healthy tooth structure should be the aim of any restorative procedure. Two inlays may be an ideal choice for the treatment of maxillary molars to preserve the transverse ridge and maintain structural integrity. PMID:21910585

Hess, T A; Wadhwani, C P K

2012-01-01

234

Characteristics of molar pregnancy in a 12 year old.  

PubMed Central

Gestational trophoblastic disease rarely is reported in early teens. This article describes a 12-year-old black female with molar disease, in which the characteristics and treatment are not dissimilar from adults.

Chapman, G. W.

1996-01-01

235

Determining Molar Combining Ratios Using Radioisotopes--A Student Experiment  

ERIC Educational Resources Information Center

Outlines an experimental procedure in which an iodine radioisotope is used to determine molar combining ratios of lead and silver with the iodine. Tables and graphs show the definitive results that should be attainable. (CP)

Sears, Jerry A.

1976-01-01

236

Mandibular First Molar with a Radix Entomolaris: An Endodontic Dilemma  

PubMed Central

It is known that the mandibular first molar can display significant anatomical variations namely the number of root canals, the number of roots and morphology. Mandibular molars may sometimes have an additional root located lingually (the radix entomolaris) or buccally (the radix paramolaris). If encountered, an awareness and understanding of this unusual root and its canal morphology can contribute to the successful outcome of root canal treatment. This case report discusses endodontic treatment of a mandibular first molar with a radix entomolaris, which is a rare entity and poses as an endodontic dilemma for the clinician with respect to diagnosis and subsequent treatment. Clinicians should be aware of these unusual root morphologies in the mandibular first molar which needs strategic treatment as unfilled canals remain a nidus for infection and can compromise treatment outcome.

Sarangi, Priyanka; Uppin, Veerendra M

2014-01-01

237

Mandibular first molar with a radix entomolaris: an endodontic dilemma.  

PubMed

It is known that the mandibular first molar can display significant anatomical variations namely the number of root canals, the number of roots and morphology. Mandibular molars may sometimes have an additional root located lingually (the radix entomolaris) or buccally (the radix paramolaris). If encountered, an awareness and understanding of this unusual root and its canal morphology can contribute to the successful outcome of root canal treatment. This case report discusses endodontic treatment of a mandibular first molar with a radix entomolaris, which is a rare entity and poses as an endodontic dilemma for the clinician with respect to diagnosis and subsequent treatment. Clinicians should be aware of these unusual root morphologies in the mandibular first molar which needs strategic treatment as unfilled canals remain a nidus for infection and can compromise treatment outcome. PMID:24910685

Sarangi, Priyanka; Uppin, Veerendra M

2014-01-01

238

Influence of molar ratios on properties of magnesium oxychloride cement  

SciTech Connect

A parametric study has been conducted to investigate the influences of the molar ratios of MgO/MgCl{sub 2} and H{sub 2}O/MgCl{sub 2} on the properties of magnesium oxychloride (MOC) cement. By an integrated assessment of the experimental studies of strength development and X-ray diffractograms, together with application of the relevant phase diagram, it is recognized that the molar ratios of MgO/MgCl{sub 2} and H{sub 2}O/MgCl{sub 2} can significantly affect the properties of MOC cement. For a MOC cement paste possessing a dominance of 5MgO.MgCl{sub 2}.8H{sub 2}O (phase 5) crystals, the molar ratios of MgO/MgCl{sub 2} of 11-17 and H{sub 2}O/MgCl{sub 2} of 12-18 are found to be the most favorite ranges for design purpose. The choose of the molar ratio of H{sub 2}O/MgCl{sub 2} is, however, largely depends on the molar ratio of MgO/MgCl{sub 2} mainly for controlling workability of paste. Therefore, the most critical parameter to be selected in the design process is the molar ratio of MgO/MgCl{sub 2}, although the reactivity of the MgO powder is also important. Besides, the molar ratio can also be affected by the reactivity of the MgO powder to be employed. It is believed that a molar ratio of MgO/MgCl{sub 2} of 13, the most suitable one shown in this study, can be used as a starting point in the normal practice.

Li Zongjin [Department of Civil Engineering, Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong (China)]. E-mail: zongjin@ust.hk; Chau, C.K. [Department of Civil Engineering, Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong (China)

2007-06-15

239

Finite Element Reconstruction of a Mandibular First Molar  

PubMed Central

Introduction Mandibular first molar is the most important tooth with complicated morphology. In finite element (FE) studies, investigators usually prefer to model anterior teeth with a simple and single straight root; it makes the results deviate from the actual case. The most complicated and time-consuming step in FE studies is modeling of the desired tooth, thus this study was performed to establish a finite element method (FEM) of reconstructing a mandibular first molar with the greatest precision. Materials and Methods An extracted mandibular first molar was digitized, and then radiographed from different aspects to achieve its outer and inner morphology. The solid model of tooth and root canals were constructed according to this data as well as the anatomy of mandibular first molar described in the literature. Result A three-dimensional model of mandibular first molar was created, giving special consideration to shape and root canal system dimensions. Conclusion This model may constitute a basis for investigating the effect of different clinical situations on mandibular first molars in vitro, especially on its root canal system. The method described here seems feasible and reasonably precise foundation for investigations.

Ehsani, Sara; Mirhashemi, Fatemeh Sadat; Asgary, Saeed

2013-01-01

240

Prediction of solubility parameters using partial least square regression.  

PubMed

The total solubility parameter (delta) values were effectively predicted by using computed molecular descriptors and multivariate partial least squares (PLS) statistics. The molecular descriptors in the derived models included heat of formation, dipole moment, molar refractivity, solvent-accessible surface area (SA), surface-bounded molecular volume (SV), unsaturated index (Ui), and hydrophilic index (Hy). The values of these descriptors were computed by the use of HyperChem 7.5, QSPR Properties module in HyperChem 7.5, and Dragon Web version. The other two descriptors, hydrogen bonding donor (HD), and hydrogen bond-forming ability (HB) were also included in the models. The final reduced model of the whole data set had R(2) of 0.853, Q(2) of 0.813, root mean squared error from the cross-validation of the training set (RMSEcv(tr)) of 2.096 and RMSE of calibration (RMSE(tr)) of 1.857. No outlier was observed from this data set of 51 diverse compounds. Additionally, the predictive power of the developed model was comparable to the well recognized systems of Hansen, van Krevelen and Hoftyzer, and Hoy. PMID:16839717

Tantishaiyakul, Vimon; Worakul, Nimit; Wongpoowarak, Wibul

2006-11-15

241

Radiographic evaluation of bone regeneration after the application of plasma rich in growth factors in a lower third molar socket: a case report  

PubMed Central

A 42-year-old Mediterranean male presented complaining of inability to sustain good oral care at the posterior aspect of the lower right jaw. The main problems were food impaction in the area and the subsequent malodor. The patient reported remarkable medical history. Clinical examination revealed local erytherma with noticeable bone defect distal to the second molar with obvious defect in the mesial wall of the third molar; the penetration depth was found to be up to 6 mm. Radiological evaluation confirmed the defect and it was attributed to the mesioangularly partially impacted lower third molar. It was decided that third molar should be extracted and concentrate of the patient's growth factors (PRGF) to be applied into the bony defect to stimulate bone regeneration and promote healing. The third molar tooth was, then, removed surgically and the PRGF, which was prepared preoperatively, was implanted in the socket. At the first postoperative day, moderate pain was the main complaint and was controlled by NSAIDs. One week postoperatively, the sutures were removed and there was good tissue healing on examination. On the fiftieth postoperative day, radiographic evaluation took place and showed noticeable enhancement of density and radio-opacity in the third molar socket area, in comparison with the baseline image. Further, clinical examination showed significant reduction of periodontal pocketing and evidence of new bone formation. In conclusion, PRGF was very successful in stimulating bone regeneration and promote healing following dental extraction.

2009-01-01

242

Genetic integration of molar cusp size variation in baboons  

PubMed Central

Many studies of primate diversity and evolution rely on dental morphology for insight into diet, behavior, and phylogenetic relationships. Consequently, variation in molar cusp size has increasingly become a phenotype of interest. In 2007 we published a quantitative genetic analysis of mandibular molar cusp size variation in baboons. Those results provided more questions than answers, as the pattern of genetic integration did not fit predictions from odontogenesis. To follow up, we expanded our study to include data from the maxillary molar cusps. Here we report on these later analyses, as well as inter-arch comparisons with the mandibular data. We analyzed variation in two-dimensional maxillary molar cusp size using data collected from a captive pedigreed breeding colony of baboons, Papio hamadryas, housed at the Southwest National Primate Research Center. These analyses show that variation in maxillary molar cusp size is heritable and sexually dimorphic. We also estimated additive genetic correlations between cusps on the same crown, homologous cusps along the tooth row, and maxillary and mandibular cusps. The pattern for maxillary molars yields genetic correlations of one between the paracone-metacone and protocone-hypocone. Bivariate analyses of cuspal homologues on adjacent teeth yield correlations that are high or not significantly different from one. Between dental arcades, the non-occluding cusps consistently yield high genetic correlations, especially the metaconid-paracone and metaconid-metacone. This pattern of genetic correlation does not immediately accord with the pattern of development and/or calcification, however these results do follow predictions that can be made from the evolutionary history of the tribosphenic molar.

Koh, Christina; Bates, Elizabeth; Broughton, Elizabeth; Do, Nicholas T.; Fletcher, Zachary; Mahaney, Michael C.; Hlusko, Leslea J.

2010-01-01

243

The Effect of Prism Orientation in the Indentation Testing of Human Molar Enamel  

PubMed Central

Recent nanoindentation studies have demonstrated that the hardness and Young's modulus of human molar enamel decreases by more than 50% on moving from the occlusal surface to the dentin-enamel junction on cross-sectional samples. Possible sources of these variations are changes in local chemistry, microstructure, and prism orientation. This study investigates the latter source by performing nanoindentation tests at two different orientations relative to the hydroxyapatite prisms: parallel and perpendicular. A single sample volume was tested in order to maintain a constant chemistry and microstructure. The resulting data show very small differences between the two orientations for both hardness and Young's modulus. The 1.5 to 3.0% difference is significantly less than the standard deviations found within the data set. Thus, the variations in hardness and Young's modulus on cross-sectional samples of human molar are attributed to changes in local chemistry (varying levels of mineralization, organic matter, and water content) and changes in microstructure (varying volume fractions of inorganic crystals and organic matrix). The impact of prism orientation on mechanical properties measured by nanoindentation appears to be minimal.

Braly, A.; Darnell, L.A.; Mann, A.B.; Teaford, M.F.; Weihs, T.P.

2007-01-01

244

The effect of prism orientation on the indentation testing of human molar enamel.  

PubMed

Recent nanoindentation studies have demonstrated that the hardness and Young's modulus of human molar enamel decreases by more than 50% on moving from the occlusal surface to the dentine-enamel junction on cross-sectional samples. Possible sources of these variations are changes in local chemistry, microstructure, and prism orientation. This study investigates the latter source by performing nanoindentation tests at two different orientations relative to the hydroxyapatite prisms: parallel and perpendicular. A single sample volume was tested in order to maintain a constant chemistry and microstructure. The resulting data show very small differences between the two orientations for both hardness and Young's modulus. The 1.5-3.0% difference is significantly less than the standard deviations found within the data set. Thus, the variations in hardness and Young's modulus on cross-sectional samples of human molar are attributed to changes in local chemistry (varying levels of mineralization, organic matter, and water content) and changes in microstructure (varying volume fractions of inorganic crystals and organic matrix). The impact of prism orientation on mechanical properties measured at this scale by nanoindentation appears to be minimal. PMID:17449008

Braly, A; Darnell, L A; Mann, A B; Teaford, M F; Weihs, T P

2007-09-01

245

Thiomers: influence of molar mass on in situ gelling properties.  

PubMed

The aim of this study was to investigate the influence of molar mass of thiolated polymers (thiomers) on their in situ gelling properties. Chitosan-thioglycolic acid (chitosan-TGA) and pectin-cysteine (pectin-Cys) of increasing molar mass were chosen to produce in situ gels in combination with carbamide peroxide. Low molar mass chitosan (~2 kDa) was prepared by oxidative degradation with NaNO(2), whereas pectin was depolymerized by heat treatment. Thiomers, displaying 1271-1616 ?mol (chitosan-TGA) and 305-403 ?mol (pectin-Cys) free thiol groups per gram polymer, were synthesized via amide bond formation mediated by a carbodiimide. The results showed that a reduction of molar mass combined with increased concentrations of both cationic chitosan-TGA and anionic pectin-Cys leads to higher final viscosities and to a higher relative increase in viscosity within 60 min and 180 min, respectively. Using this method, the dynamic viscosity of a very low molar mass chitosan-TGA (~2 kDa) could be increased 100,000-fold within 60 min and 390,000-fold within 180 min. In view of these in situ gelling properties carbohydrate thiomers might be useful for various pharmaceutical applications such as vehicle for drug delivery or as wound dressing material. PMID:22683454

Hintzen, Fabian; Laffleur, Flavia; Sarti, Federica; Shahnaz, Gul; Bernkop-Schnürch, Andreas

2012-10-15

246

Partial oxidation catalyst  

DOEpatents

A two-part catalyst comprising a dehydrogenation portion and an oxide-ion conducting portion. The dehydrogenation portion is a group VIII metal and the oxide-ion conducting portion is selected from a ceramic oxide crystallizing in the fluorite or perovskite structure. There is also disclosed a method of forming a hydrogen rich gas from a source of hydrocarbon fuel in which the hydrocarbon fuel contacts a two-part catalyst comprising a dehydrogenation portion and an oxide-ion conducting portion at a temperature not less than about 400.degree. C. for a time sufficient to generate the hydrogen rich gas while maintaining CO content less than about 5 volume percent. There is also disclosed a method of forming partially oxidized hydrocarbons from ethanes in which ethane gas contacts a two-part catalyst comprising a dehydrogenation portion and an oxide-ion conducting portion for a time and at a temperature sufficient to form an oxide.

Krumpelt, Michael (Naperville, IL); Ahmed, Shabbir (Bolingbrook, IL); Kumar, Romesh (Naperville, IL); Doshi, Rajiv (Downers Grove, IL)

2000-01-01

247

Surgical extraction of mandibular third molar in pterygomandibular space: a case report  

PubMed Central

Impacted mandibular third molars are located between the second mandibular molar and mandibular ramus. However, ectopic mandibular third molars with heterotopic positions are reported in the subcondylar or pterygomandibular space. The usual cause of malposition is a cyst or tumor, and malposition without a pathology is rare. This case report described an impacted mandibular third molar in the pterygomandibular space without any associated pathology.

Lee, Young-Kyu; Park, Sung-Soo

2013-01-01

248

Efficacy of Postoperative Prophylactic Antibiotic Therapy in Third Molar Surgery  

PubMed Central

Introduction: Surgical extraction of mandibular third molar is the most frequently performed procedure in oral surgery. This procedure is associated with significant postoperative sequelae such as trismus, swelling, pain and infection. The need of antibiotic therapy during the removal of mandibular third molar has been a contentious issue. Method: This study investigated a regimen by using amoxycillin and metronidazole in one group and without using antibiotics in the other. Both the groups were assessed postoperatively on the 1st, 2nd, 5th, 7th and 10th days by the same observer for post operative mouth opening (interincisal distance), presence of a purulent discharge at the site of surgery, pain and swelling. Result: Overall, no statistically significant difference was seen between both the treatment groups when interincisal distance, pain, swelling and purulent discharge were considered. Conclusion: The results of this study failed to show any advantage which was associated with the routine postoperative use of antibiotics in asymptomatic third molar surgeries.

Reddy B, Praveen

2014-01-01

249

[Hypodontia with anlage of all four third molars].  

PubMed

Orthopantomographic films and anamnestic data of 1553 orthodontic patients presenting four third molars were evaluated for tooth agenesis. Agenesis was found in 94 patients (6.1%). There were no significant differences between male and female patients. The most commonly missing teeth were the lower second premolars followed by the upper lateral incisors and the upper second premolars in decreasing order of frequency. Compared with the data in the literature, these results suggest that agenesis occurs less frequently in patients with anlage of all four third molars. PMID:2269104

Roth, P; Hirschfelder, U

1990-05-01

250

Treatment of Ectopic Mandibular Second Permanent Molar with Elastic Separators  

PubMed Central

Ectopic eruption is a developmental disturbance in which the tooth fails to follow its normal eruption pathway. Ectopic eruption of the second molar is relatively rare. This paper presents the case of thirteen-year-old male with an ectopic mandibular second permanent molar. The condition was corrected with surgical exposure and placement of elastic separators. This case report lays emphasis on the practice of basic methods to obtain acceptable results rather than extensive surgical or orthodontic corrections. It is advised that ectopic teeth should not be neglected especially when it concerns developing caries and malocclusion.

Rajesh, R.; Naveen, V.; Amit, S.; Baroudi, Kusai; Sampath Reddy, C.; Namineni, Srinivas

2014-01-01

251

On the Molar Extinction Coefficient and Integrated Molar Absorptivity of the Infrared Absorption Spectra of C60 and C70 Fullerenes  

Microsoft Academic Search

The molar extinction coefficients, known also as molar absorptivity ?, of C60 and C70 fullerenes infrared absorption spectra were determined at room temperature on samples embedded in KBr pellets. Furthermore, the integrated molar absorptivity ? of each absorption infrared band either of C60 and of C70 was measured and reported together with the relative intensity of the infrared absorption bands.

Franco Cataldo; Susana Iglesias-Groth; Arturo Manchado

2012-01-01

252

Subjective values of different treatments for missing molars in older Japanese.  

PubMed

The purpose of this study was to determine how elderly Japanese people subjectively value treatment options for missing molars. Subjects were 528 independently community-dwelling elderly people. They were presented with photographs and descriptions of the process and expected outcomes of five possible treatment options: cantilever fixed dental prosthesis (FDP); resin or metal removable partial denture prosthesis (RPDP); implant-supported fixed prosthesis; and no replacement (shortened dental arch: SDA) for missing lower bilateral first and second molars. The participants filled in the questionnaire on subjective importance for treatment and indicated on a visual analogue scale how they valued the treatment (utility value: UV). Values were analysed by Mann-Whitney U-tests and multiple logistic regression analyses. Overall, the UVs for the FDP and the metal RPDP were the highest, and the UV for the SDA was the lowest. With respect to subjective importance, 'chewing ability' and 'no pain during function' were significantly selected more frequently. Multiple logistic regression analyses showed that the UV for the resin RPDP had significant positive associations with denture wearers and low treatment cost, whereas the implant had significant negative associations with denture wearers and older age. The SDA had significant positive associations with men and low treatment cost and a negative association with appearance. In conclusion, these elderly Japanese preferred cantilever FDPs and metal RPDPs to implants and 'no replacement.' It suggests that the SDA as an oral health goal can be questionable from the patients' point of view, even if it is biologically correct. PMID:20633073

Ikebe, K; Hazeyama, T; Kagawa, R; Matsuda, K; Maeda, Y

2010-12-01

253

Effect of unilateral extraction of molar teeth on suprahyoid muscles: macroscopic and ultrastructural aspects.  

PubMed

Anatomical and physiologic components are parts of the stomatognathic system and their interaction results in integrated functional activities. Important alterations in the masticatory system originated by dental loss affect the bone, oral mucosa and muscular function. Dental arch structures specifically designed to receive and expose teeth allow performance of their functions. But the distinction between bony and soft tissues is lost when teeth are removed since there is not a specific function to be completed. The aim of this study was to evaluate the macroscopic and ultrastructural effects of the unilateral extraction of molar teeth on the suprahyoid muscles function, using twenty young male gerbils (Meriones unguiculatus) as the experimental animal model. They were divided in experimental malocclusion (n=10) and control (n=10) groups. The experimental malocclusion group was submitted to exodontia of the left upper molars and the control group was not submitted to this procedure and served as sham-operated. For macroscopic analysis of the suprahyoid muscle, the skin was uplifted and the muscles dissected individually and removed for weight analysis according to Scherle method. The electron microscopy analysis was made in ultra thin sections of small suprahyoid muscle fragments from the experimental and control groups, examined in a Jeol 1010, 880 Kv transmission electron microscope. Several micrographs at magnifications of 3000x, 6000x, 30,000x were randomly selected for the qualitative analysis of the muscle fiber ultrastructures. Sixty days after the induced unilateral occlusal alteration no macroscopic morphologic changes was detected in the suprahyoid muscles and the muscle volume differences between the right and left sides and between groups were not significant. However, in the ultrastructural analysis suprahyoid muscles showed characteristics of specific adaptation to the unilateral occlusal alteration, by the reduced density of subsarcolemmal mitochondria and the shorter and less numerous ramifications in intermyofibrilar mitochondria localized between electronlucid myofibrils. It is concluded that unilateral exodontia of all the upper left molars affect the ultrastructural morphology of suprahyoid muscle fibers. PMID:18693023

Iyomasa, Mamie Mizusaki; Issa, João Paulo Mardegan; Siéssere, Selma; Regalo, Simone Cecílio Hallak; Watanabe, Ii-sei

2008-12-01

254

Infected Dentigerous Cyst of Maxillary Sinus Arising from an Ectopic Third Molar  

PubMed Central

A dentigerous cyst or follicular cyst is a form of odontogenic cyst. It is believed that it forms during the development of the tooth and is associated with pressure exerted by the crown of an unerupted (or partially erupted) tooth on the fluid within the follicular space. Typically, dentigerous cysts are painless and discovered during routine radiographic examination. However, they may be large and result in a palpable mass. Additionally, as they grow they displace adjacent teeth. They almost exclusively occur in permanent dentition. The cyst is lined by stratified squamous non-keratinizing epithelium. About 70% of dentigerous cysts occur in the mandible and 30% in the maxilla. Dentigerous cysts associated with ectopic teeth within the maxillary sinus are very rare. We report radiologic and pathologic features in a rare case of infected dentigerous cyst of maxillary sinus arising from an ectopic third molar in a 21-year-old female patient.

Guruprasad, Yadavalli; Chauhan, Dinesh Singh; Kura, Umashankar

2013-01-01

255

Forces produced by lip bumpers on mandibular molars  

Microsoft Academic Search

The purpose of this study was to measure the forces produced by a lip bumper on the mandibular permanent first molars. The forces in a simple of 38 patients were measured bilaterally with specially designed gauges at rest but with their lips lightly touching, speaking the words church, phone, and pop, and swallowing water. Forces were compared between two types

John J. Hodge; Ram S. Nanda; Joydeep Ghosh; David Smith

1997-01-01

256

[Unusual complication of extraction of a third molar].  

PubMed

The authors summarized the technical problems of the Wisdom teeth extraction. They advised to send the patients from the basic dental service to the aMaxillofacial Surgery Departments if the position of tooth is unfavourable. They reported a complicated case of the third molar extraction. PMID:10423921

Szabó, C; Csáki, G; Bögi, I

1999-06-01

257

Mathematical analysis of furcation angle in extracted mandibular molars  

PubMed Central

Background: Multi-rooted teeth with furcation involvement exhibit a poorer prognosis when compared to single rooted teeth. The furcation angle (formed by the divergent roots and the roof) may exert a considerable influence on the accessibility for both home care maintenance and instrumentation during periodontal therapy. As there are few anatomy based reports, the furcation angle has not yet been delineated. Materials and Methods: Furcation angle (FA) was mathematically evaluated in extracted mandibular first and second molar teeth, using the Computer-aided design - computer-aided manufacturing technology. Results: The furcations were divided into three groups (Group I: <30°, Group II: 30°-60°, Group III: >60°) based on the furcation angle and their prevalence. The first molar showed greater prevalence of group II FA, while second molar showed a greater prevalence of group III FA. Conclusion: Linear, two dimensional measurements may not accurately reflect the complexities of the furcation area which exhibits considerable intermolar and intramolar (buccal and lingual furcations of second molar) variation.

James, Johnson R.; Arun, K. V.; Talwar, Avaneendra; Kumar, T. S. S.

2013-01-01

258

The current clinical presentation of complete molar pregnancy  

Microsoft Academic Search

Objective: To study the current clinical presentation of complete molar pregnancy. Method: Retrospective study of the clinical and ultrasonographic records of 41 patients with complete hydatidiform mole. Results: 17 (41%) patients were asymptomatic. 24 patients (58%) presented with vaginal bleeding, 6 (15%) had excessive uterine size,\\u000a 1 (2%) had anemia and 1 (2%) had hyperemesis. Non of the patients had

Ofer Gemer; Shmuel Segal; Alexander Kopmar; Essi Sassoon

2000-01-01

259

A geometric morphometric analysis of hominin upper first molar shape  

Microsoft Academic Search

Recent studies have revealed interesting differences in upper first molar morphology across the hominin fossil record, particularly significant between H. sapiens and H. neanderthalensis. Usually these analyses have been performed by means of classic morphometric methods, including the measurement of relative cusp areas or the angles defined between cusps. Although these studies have provided valuable information for the morphological characterization

A. Gómez-Robles; M. Martinón-Torres; J. M. Bermúdez de Castro; A. Margvelashvili; M. Bastir; J. L. Arsuaga; A. Pérez-Pérez; F. Estebaranz; L. M. Martínez

2007-01-01

260

Survival rates of porcelain molar crowns-an update.  

PubMed

The aim of this study was to identify recent studies that dealt with the clinical performance of porcelain molar crowns and to explore the possibility of grouping the findings from similar studies together to draw overall conclusions. A MEDLINE literature search was conducted in early 2009 covering the preceding 12 years. Seventeen studies were indentified. However, only seven met the specific inclusion criteria and were analyzed. Among seven studies, five European countries were covered. Five studies reported on Procera AllCeram molar crowns while one reported on In-Ceram Alumina and Spinell crowns and another on CEREC crowns. For comparison, one additional study that reported on premolar crowns was included. In the five Procera AllCeram studies, 235 molar crowns were evaluated for 5 or more years, of which 24 failed. When the results of the five studies on the performance of Procera AllCeram molar crowns were considered collectively, an overall failure rate of 10.2% was found at 5 or more years. Int J Prosthodont 2010;23:60-62. PMID:20234895

Kassem, Amr Shebl; Atta, Osama; El-Mowafy, Omar

2010-01-01

261

Factors associated with molar incisor hypomineralization in Thai children.  

PubMed

Molar incisor hypomineralization (MIH) is a qualitative developmental enamel defect that affects one to four permanent first molars, with or without involvement of permanent incisors. Its etiology is of systemic origin, but is not well understood. Therefore, we conducted this cross-sectional study to examine pre-, peri-, and postnatal risk factors for MIH among children, 7-8 yr of age, in urban areas of Khon Kaen, Thailand. Molar incisor hypomineralization defects were diagnosed using the European Academy of Pediatric Dentistry criteria. Mothers or primary caregivers were interviewed on maternal medical history and habits during pregnancy, pregnancy and delivery complications, and the child's medical history. Molar incisor hypomineralization defects were observed in 78 (27.7%) of 282 children. Multiple logistic regression analysis showed a statistically significant association between the development of MIH and Cesarean section (adjusted OR = 2.0, 95% CI = 1.1-3.7), complications during vaginal delivery (adjusted OR = 4.5, 95% CI = 1.9-11.0), and severe/chronic illness when under 3 yr of age (adjusted OR = 2.9, 95% CI = 1.6-5.0). There was no association of preterm birth and low birth weight with MIH. The results suggest that Cesarean section, complications during vaginal delivery, and poor health during the first 3 yr of life are independent risk factors for MIH. PMID:24924351

Pitiphat, Waranuch; Luangchaichaweng, Sarunporn; Pungchanchaikul, Patimaporn; Angwaravong, Onauma; Chansamak, Nusara

2014-08-01

262

Third Molar Polymorphism and the Timing of Tooth Formation  

Microsoft Academic Search

AGENESIS (congenital absence) of the third molar tooth is a familiar polymorphism in man, with a population frequency of at least 9 per cent in Europeans1. Hitherto, congenital absence of this tooth has been considered as an independent trait, or at most associated with reduction in size when agenesis is incomplete. However, there is evidence connecting the presence or absence

Stanley M. Garn; Arthur B. Lewis; Batsheva Bonné

1961-01-01

263

A permanent mandibular second molar with seven root canal systems.  

PubMed

This case report illustrates the nonsurgical endodontic management of a seven-canaled mandibular second molar. The root canal configuration presented as four mesial and three distal canals. Identification of the canal system was made with the aid of magnification, ultrasonics, and multiple angulated radiographs. Postoperative examination at 18 months showed a clinically asymptomatic tooth with resolution of the periapical pathology. PMID:24634902

Kottoor, Jojo; Paul, Kuriachan Kottanathu; Mathew, Joy; George, Saira; Mathew, Jain; Roy, Arun

2014-05-01

264

Genotype, phenotype, and developmental biology of molar tooth characters  

Microsoft Academic Search

Primate molar shapes reflect developmental and ecological processes. Development may constrain as well as facilitate evolution of new tooth shapes, affecting how reliable dental characters are in phylogenetic studies. Much of the genetic machinery of development uses the same genes among different organs, including teeth, limbs, and feathers. Furthermore, within a tooth, the development of individual cusps repeatedly uses the

Jukka Jernvall

2000-01-01

265

An odor interaction model of binary odorant mixtures by a partial differential equation method.  

PubMed

A novel odor interaction model was proposed for binary mixtures of benzene and substituted benzenes by a partial differential equation (PDE) method. Based on the measurement method (tangent-intercept method) of partial molar volume, original parameters of corresponding formulas were reasonably displaced by perceptual measures. By these substitutions, it was possible to relate a mixture's odor intensity to the individual odorant's relative odor activity value (OAV). Several binary mixtures of benzene and substituted benzenes were respectively tested to establish the PDE models. The obtained results showed that the PDE model provided an easily interpretable method relating individual components to their joint odor intensity. Besides, both predictive performance and feasibility of the PDE model were proved well through a series of odor intensity matching tests. If combining the PDE model with portable gas detectors or on-line monitoring systems, olfactory evaluation of odor intensity will be achieved by instruments instead of odor assessors. Many disadvantages (e.g., expense on a fixed number of odor assessors) also will be successfully avoided. Thus, the PDE model is predicted to be helpful to the monitoring and management of odor pollutions. PMID:25010698

Yan, Luchun; Liu, Jiemin; Wang, Guihua; Wu, Chuandong

2014-01-01

266

Influence of third molar space on angulation and dental arch crowding.  

PubMed

The influence of the third molars on mandibular incisor crowding has been extensively studied but remains controversial. The purpose of this study was to ascertain whether, in Mongolian subjects, the lower third molar can affect anterior crowding and/or the inclination of teeth in the lower lateral segments. Panoramic radiographs, 45° oblique cephalograms, and dental casts were taken from Mongolian subjects (age range 18.3-24.1 years, mean 21.0 years) exhibiting impaction of all four third molars and an Angle Class I molar relationship. The Ganss ratio was calculated using panoramic radiographs, whereas the gonial angle and angulation of lower canines, premolars and molars were measured using 45° oblique cephalograms. Little's index of irregularity was calculated using dental casts. Significant relationships between the angulation of the third and second molars and between the first molars and second premolars were found. Conversely, there was no significant correlation between the angulation of third molars, first premolars and canines. The Ganss ratio calculations showed that the lower first and second molars and the second premolars inclined mesially if there was insufficient space for the lower third molars. However, there was no significant correlation between Little's index of irregularity and third molar angulation. Furthermore, although the third molar influences the lateral segments, no obvious relationship between the third molar and anterior crowding was observed. Therefore, the angulation of the third molar appears not to cause anterior crowding. PMID:22527908

Hasegawa, Yuh; Terada, Kazuto; Kageyama, Ikuo; Tsuchimochi, Takashi; Ishikawa, Fujiro; Nakahara, Sen

2013-01-01

267

Representations of partial derivatives in thermodynamics  

NSDL National Science Digital Library

One of the mathematical objects that students become familiar with in thermodynamics, often for the first time, is the partial derivative of a multivariable function. The symbolic representation of a partial derivative and related quantities present difficulties for students in both mathematical and physical contexts, most notably what it means to keep one or more variables fixed while taking the derivative with respect to a different variable. Material properties are themselves written as partial derivatives of various state functions (e.g., compressibility is a partial derivative of volume with respect to pressure). Research in courses at the University of Maine and Oregon State University yields findings related to the many ways that partial derivatives can be represented and interpreted in thermodynamics. Research has informed curricular development that elicits many of the difficulties using different representations (e.g., geometric) and different contexts (e.g., connecting partial derivatives to specific experiments).

Thompson, John R.; Manogue, Corinne A.; Roundy, David J.; Mountcastle, Donald B.

2012-05-15

268

Molar luxations caused by holding water taps. Report of five cases.  

PubMed

Luxation of a primary molar occurs rarely. Here, we describe five cases of primary molar luxation caused by holding a water tap pipe in the mouth during bathing. The patients were aged 16 to 19 months and the mandibular first primary molar was affected in all five cases. The second primary molar had not erupted. It is assumed that the flange of the pipe got stuck in the interdental space between the mandibular primary canine and first primary molar and the affected first molar was pushed out by force with the flange acting as a lever. PMID:24579277

Horie, Norio; Hino, Shunsuke; Fukai, Shunichi; Kaneko, Takahiro; Shimoyama, Tetsuo

2013-01-01

269

A Physiological Permeability Study of Third Molar Dentine with Odontoblasts Preserved and Odontoblasts Free Preparations  

PubMed Central

Introduction Dentine a viable biological tissue forms an intimately related complex with the odontoblasts. Much has been question of the barrier properties of dentine within teeth and between teeth.. In human adults the odontoblasts are fully differentiated post-mitotic cells, which send its cytoplasmic processes into the dentinal tubules, yet various studies in the physic of fluid flow in dentine takes little recognition of its presence. The permeability of dentine has been implicated in a possible hydrodynamic mechanism by which rapid fluid movement in the tubules is thought to depolarise the nerve endings. Objective The innovative aim from this pilot investigation is to contribute to the understanding of the influence of odontoblasts on the permeability of human dentine. Methodology This study describes the permeability in odontoblast preserved and odontoblast free preparations in vitro i.e. comparing fluid flow across dentine in human third molars. The pulp tissues were removed from human third molars leaving the odontoblasts attached to the walls of the chamber. The specimens were then either fixed chemically (odontoblast-preserved specimens) or immersed in NaOH (odontoblast free specimens). Occlusal dentine was exposed by removing the enamel. The exposed dentine was placed in contact with water and the ingress of water into the pulp chamber was observed with a binocular microscope. A microlitre syringe was used to measure the volume of water accumulated at time intervals of several hours for up to 70 hours or more. Results The results showed that spontaneous flow continued in both preparations until equilibrium was reached. The relative final volumes were greater in the odontoblast free preparations than in the odontoblast preserved. Conclusion Water movement through odontoblast free dentine was believed to be driven by capillarity and through odontoblast preserved dentine by capillarity and osmotic pressure.

Ghazali, Farid Che

2000-01-01

270

Molar extinction coefficients of the cupric ion in silicate glasses  

Microsoft Academic Search

The absorption characteristics of Cu2+ ions in binary alkali silicate and ternary silicate glasses were investigated. The molar extinction coefficients of the Cu2+ ion were determined in a series of binary alkali silicate and a ternary soda-lime-silica glasses for the actual intensities of the observed bands at their wavelength maxima. The absorption maxima due to Cu2+ ions were found to

S. P. Singh; A. Kumar

1995-01-01

271

Temporal abscess after third molar extraction in the mandible  

Microsoft Academic Search

Background  Dental infections resulting before or after third molar removal are complications in which the maxillofacial surgeon may have\\u000a to initiate an earlier management. The severe dental infections resulting before or after this procedure is one of the few\\u000a life-threatening complications in which the maxillofacial surgeon may have to initiate an earlier management. Infections involving\\u000a the temporal space are rare and

Patrício José de Oliveira Neto; Maximiana Cristina de Souza Maliska; Renato Sawazaki; Luciana Asprino; Márcio de Moraes; Roger William Fernandes Moreira

272

Better outcomes in pulpotomies on primary molars with MTA  

Microsoft Academic Search

Data sourcesMedline, Cochrane Library, Embase, Science Citation Index and the China National Knowledge Infrastructure were used to source articles. In addition, identified papers' reference lists and their authors' other published literature were also scanned.Study selectionStudies of interest were randomised controlled trials of primary molar teeth where there was exposure of vital pulp caused by caries or trauma, with at least

Nicola Innes

2007-01-01

273

Molar concentration effect on MgO thin films properties  

Microsoft Academic Search

Magnesium Oxide, MgO is inorganic material with wide band gap (7.8eV) and suitable to be used as dielectric layer. Due to its chemical and structural properties, MgO also can be used as template to prepare ferroelectric thin film [1–3]. In this work, MgO thin films with different molar concentration from 0.1M to 1M were prepared using sol-gel spin coating technique.

Habibah Zulkefle; Lyly Nyl Ismail; Raudah Abu Bakar; Mohamad Rusop Mahmood

2011-01-01

274

Evaluation of Impacted Mandibular Third Molars by Panoramic Radiography  

PubMed Central

Objective. The study was to evaluate impacted mandibular third molars (IM3M) for their angulation, level of eruption, third molar space and relation of inferior alveolar canal with their roots. Methods. Total 988 IM3M were studied in 578 individuals of age 18?years and above, dividing them into three groups i.e. symptomatic, asymptomatic and radiographic only. Individuals were also divided according to age, sex and side of IM3M (right or left). Panoramic radiographs were obtained after written consent and traced. ?2-test was applied to check inter-group and intra-group significance. Result. Out of 578 individuals 307 (53.11%) were males and 271 (46.89%) females. Maximum number of IM3M were in 18-27?years age group (398 i.e. 68.89%). Out of 988 IM3M, 39.93% were vertically placed. 61.84% IM3M were found at level A. Class II (79.65%) was the most common relation for third molar space. Notching (12.55%) was most common true inferior alveolar canal and IM3M root relation whereas superimposed (41.80%) was most common false inferior alveolar canal and IM3M root relation. For all the criteria significant inter-group difference was found (considering P < .05) and intra-group difference was non significant. Conclusion and significance. Panoramic radiographs can be used as reliable investigation for evaluation of IM3M.

Gupta, Siddharth; Bhowate, Rahul R.; Nigam, Nitin; Saxena, Sonal

2011-01-01

275

Quality of life following third molar removal under conscious sedation  

PubMed Central

Aim: The aim of this study was to assess quality of life (QoL) and degree of satisfaction among outpatients subjected to surgical extraction of all four third molars under conscious sedation. A second objective was to describe the evolution of self-reported pain measured in a visual analogue scale (VAS) in the 7 days after extraction. Study design: Fifty patients received a questionnaire assessing social isolation, working isolation, eating and speaking ability, diet modifications, sleep impairment, changes in physical appearance, discomfort at suture removal and overall satisfaction at days 4 and 7 after surgery. Pain was recorded by patients on a 100-mm pain visual analogue scale (VAS) every day after extraction until day 7. Results: Thirty-nine patients fulfilled correctly the questionnaire. Postoperative pain values suffered small fluctuations until day 5 (range: 23 to 33 mm in a 100-mm VAS), when dicreased significantly. A positive association was observed between difficult ranked surgeries and higher postoperative pain levels. The average number of days for which the patient stopped working was 4.9. Conclusion: The removal of all third molars in a single appointment causes an important deterioration of the patient’s QoL during the first postoperative week, especially due to local pain and eating discomfort. Key words:Third molar removal, quality of life, sedation.

Sancho-Puchades, Manuel; Berini-Aytes, Leonardo; Gay-Escoda, Cosme

2012-01-01

276

Group Contribution to Molar Refraction and Refractive Index of Conjugated Polymers.  

National Technical Information Service (NTIS)

The functional group contribution to molar refraction and refractive index of pi-conjugated polymers has been evaluated from the available refractive index dispersion data for 33 conjugated polymers. The Lorentz-Lorenz molar refraction (Ru) of 24 function...

C. J. Yang S. A. Jenekhe

1996-01-01

277

Correlation of Acute Pericoronitis and the Positon of the Mandibular Third Molar.  

National Technical Information Service (NTIS)

Acute pericoronitis is a painful, debilitating infection that is most commonly found among young adults with erupting mandibular third molars. Prophylactic removal of third molars to prevent this disease has been advocated, but this procedure requires an ...

S. A. Leone M. J. Edenfield M. E. Cohen

1987-01-01

278

Hypercementosis and concrescence of maxillary second molar with third molar: a case report and review of literature.  

PubMed

Concrescence signifies a rare developmental alteration, most commonly in maxillary molars,where two fully formed teeth with separate root canal structures are fused with cementum. Clinical detection is difficult due to lack of enamel involvement and radiographic detection may be challenging, as two dimensional images may be misdiagnosed as overlap, superimposition or close proximity of roots. Such a developmental anomaly can influence treatment outcomes for extraction, endodontic, periodontic, prosthodontic and orthodontic treatment. Legal complications could arise due to unexpected difficulties following treatment. Awareness of occurrence, incidence and post treatment implications of such anomalies is paramount for both the patient and clinician's benefit. This article discusses a case report of concrescence between two maxillary molar teeth and its management. PMID:24984682

Mohan, Bhavya

2014-06-01

279

A comparative study between lip bumper and headgear as maxillary molar retainers following distalization.  

PubMed

Abstract: There are many appliances that can be used to correct molar relationship, achieving upper molar distalization, in Class II malocclusion. This research aimed to study the dental effects promoted by lip bumper to retain maxillary molars that had previously been distalized using a Cetlin appliance in conjunction with headgear. PMID:23094556

Silva, Rafael Games Corrêa; Kaieda, Armando Koichiro; Paranhos, Luiz Renato; Angelieri, Fernanda; Torres, Fernando César; Scanavini, Marco Antônio

2012-01-01

280

Influence of Alkoxide Molar Ratio on Rheological Study of Alumina Sol for Fiber Preparation  

Microsoft Academic Search

Various molar ratio of aluminium isopropoxide (ALP) to aluminium nitrate nonahydrate (ALN) ranging from 1 to 5 were studied to determine suitable molar ratio in producing alumina fiber. Spinnability characteristics obtained only from intermediate molar ratio, 3, where the rheological shows Newtonian behavior. The spinned gel fiber were calcined at different temperatures ranging from 500°C to 1200°C. The rheological studies

M. Hasmaliza; M. N. Ahmad Fauzi; A. Zainal Arifin

2008-01-01

281

Partial tooth gear bearings  

NASA Technical Reports Server (NTRS)

A partial gear bearing including an upper half, comprising peak partial teeth, and a lower, or bottom, half, comprising valley partial teeth. The upper half also has an integrated roller section between each of the peak partial teeth with a radius equal to the gear pitch radius of the radially outwardly extending peak partial teeth. Conversely, the lower half has an integrated roller section between each of the valley half teeth with a radius also equal to the gear pitch radius of the peak partial teeth. The valley partial teeth extend radially inwardly from its roller section. The peak and valley partial teeth are exactly out of phase with each other, as are the roller sections of the upper and lower halves. Essentially, the end roller bearing of the typical gear bearing has been integrated into the normal gear tooth pattern.

Vranish, John M. (Inventor)

2010-01-01

282

p57KIP2 immunohistochemistry in early molar pregnancies: emphasis on its complementary role in the differential diagnosis of hydropic abortuses.  

PubMed

Morphologic examination still forms the main diagnostic tool in the differential diagnosis of molar pregnancies. However, the criteria are subjective and show considerable interobserver variability among pathologists. Once a diagnosis of molar pregnancy is made, DNA ploidy studies help to differentiate a triploid partial mole from diploid complete mole (CM). However, with earlier diagnosis and therapeutic evacuation of molar pregnancies, the differentiation of molar pregnancies from early nonmolar placentation is becoming increasingly difficult. The p57(KIP2) gene ( CDKN1C ) is strongly paternally imprinted and expressed from the maternal allele. Because CM lacks a maternal genome, p57(KIP2) immunostaining is correspondingly absent, whereas hydropic abortuses and partial mole show positive staining. We compared the use of p57(KIP2) staining in the differential diagnosis of 68 morphologically challenging cases of early first-trimester hydropic placentas. Diagnosis based on p57(KIP2) staining was compared with the original diagnosis based on morphology and DNA ploidy analysis. Concordant results were obtained in 65 of 68 cases studied. In 2 of 3 cases with a discordant diagnosis, microsatellite DNA genotyping analysis agreed with the results of p57(KIP2) staining, confirming that positive p57(KIP2) staining is a highly sensitive and specific marker for excluding CM in this setting. In addition, p57(KIP2) staining has the advantage of differentiating hydropic abortuses from CMs, a distinction not made by ploidy analysis. p57(KIP2) staining can be used in concert with ploidy studies to refine the diagnosis of early molar pregnancies. PMID:15754295

Merchant, Shakil H; Amin, Mitual B; Viswanatha, David S; Malhotra, Rajwant K; Moehlenkamp, Cynthia; Joste, Nancy E

2005-02-01

283

Initial Clinical Experience With the Strut-Adjusted Volume Implant (SAVI) Breast Brachytherapy Device for Accelerated Partial-Breast Irradiation (APBI): First 100 Patients With More Than 1 Year of Follow-Up  

SciTech Connect

Purpose: The Strut-Adjusted Volume Implant (SAVI; Cianna Medical, Aliso Viejo, CA) is a multichannel single-entry brachytherapy device designed to allow dose modulation to minimize normal tissue dose while simultaneously maximizing target coverage. This is the first report on the initial 102 patients with nearly 2 years of median follow-up. Methods and Materials: One hundred two patients were treated at two institutions. Data were collected on eligibility and dosimetry and followed for toxicity and recurrence. Results: The median follow-up is 21 months. Overall dosimetry is outstanding (median percent of target volume receiving 90% of the prescription dose was 95.9%, volume of target receiving 150% of the prescription dose was 27.8 mL, and volume of target receiving 200% of the prescription dose was 14.0 cm{sup 3}). No devices were pulled prior to treatment completion. For patients with a skin bridge of less than 7 mm, the maximum median skin dose was 280 cGy (median percent of target volume receiving 90% of the prescription dose was 95.2%, volume of target receiving 150% of the prescription dose was 25.8 cm{sup 3} and volume of target receiving 200% of the prescription dose was 12.7 mL). For patients with both chest wall and skin of less than 7 mm, the maximum median lung dose was 205 cGy with simultaneous skin dose of 272 cGy. The rate of telangiectasia was 1.9%. Grade 1 hyperpigmentation developed in 10 patients (9.8%) and Grade 2 fibrosis in 2 patients (1.9%). There were 2 symptomatic seromas and 2 cases of asymptomatic fat necrosis (1.9%). Of the patients, 27% were not eligible for MammoSite balloon brachytherapy (Hologic, Inc., Marlborough, MA) and 5% were not eligible for any balloon brachytherapy. The recurrence rate was 1%. Conclusions: The SAVI appears to safely allow an increase in eligibility for APBI over balloon brachytherapy or three-dimensional conformal radiation, highlighting the outstanding device flexibility to maximize the target dose and minimize the normal tissue dose. The device was well tolerated by patients.

Yashar, Catheryn M., E-mail: cyashar@ucsd.edu [Department of Radiation Oncology, University of California San Diego, La Jolla, CA (United States); Scanderbeg, Daniel [Department of Radiation Oncology, University of California San Diego, La Jolla, CA (United States); Kuske, Robert [Arizona Breast Cancer Specialists, Phoenix, AZ (United States); Wallace, Anne [Department of Surgery, University of California San Diego, La Jolla, CA (United States); Zannis, Victor [Breast Care Center of the Southwest, Phoenix, AZ (United States); Blair, Sarah [Department of Surgery, University of California San Diego, La Jolla, CA (United States); Grade, Emily; Swenson, Virginia H. [Arizona Oncology Services Foundation, Phoenix, AZ (United States); Quiet, Coral [Arizona Breast Cancer Specialists, Phoenix, AZ (United States)

2011-07-01

284

A method for estimating both the solubility parameters and molar volumes of liquids  

NASA Technical Reports Server (NTRS)

Development of an indirect method of estimating the solubility parameter of high molecular weight polymers. The proposed method of estimating the solubility parameter, like Small's method, is based on group additive constants, but is believed to be superior to Small's method for two reasons: (1) the contribution of a much larger number of functional groups have been evaluated, and (2) the method requires only a knowledge of structural formula of the compound.

Fedors, R. F.

1974-01-01

285

Densities and molar volumes of refined sodium oxide-containing slag melts  

Microsoft Academic Search

The refined slag mixtures used in electric-arc furnaces and ladle?furnace units usually contain up to 20? 30% fluorite. It is important to replace fluorite, which is employed as a thinning agent for highly basic refining slags, especially from an ecological viewpoint, since CaF 2 decomposes in the zone of electric arcs to yield anhydrous hydrogen fluoride. To form free-running refining

I. A. Magidson; A. V. Basov; N. A. Smirnov; M. V. Ezova

2007-01-01

286

Measurements on Melting Pressure, Metastable Solid Phases, and Molar Volume of Univariant Saturated Helium Mixture  

NASA Astrophysics Data System (ADS)

A concentration-saturated helium mixture at the melting pressure consists of two liquid phases and one or two solid phases. The equilibrium system is univariant, whose properties depend uniquely on temperature. Four coexisting phases can exist on singular points, which are called quadruple points. As a univariant system, the melting pressure could be used as a thermometric standard. It would provide some advantages compared to the current reference, namely pure He, especially at the lowest temperatures below 1 mK. We have extended the melting pressure measurements of the concentration-saturated helium mixture from 10 to 460 mK. The density of the dilute liquid phase was also recorded. The effect of the equilibrium crystal structure changing from hcp to bcc was clearly seen at mK at the melting pressure MPa. We observed the existence of metastable solid phases around this point. No evidence was found for the presence of another, disputed, quadruple point at around 400 mK. The experimental results agree well with our previous calculations at low temperatures, but deviate above 200 mK.

Rysti, J.; Manninen, M. S.; Tuoriniemi, J.

2014-06-01

287

Mandibular third molar development after mantle radiation in long-term survivors of childhood Hodgkin's disease  

SciTech Connect

Sequential panoramic radiographs were assessed for mandibular third molar development in 47 long-term survivors of childhood Hodgkin's disease after treatment with 37 Gy mantle field radiation. To make a comparison, panoramic radiographs of 149 healthy, nonirradiated children were reviewed for the presence of mandibular third molars. In children between the ages of 7 and 12 years, bilateral agenesis of mandibular third molars was more frequent in patients who had been treated with mantle radiation than in nonirradiated patients. Unilateral agenesis, crown hypoplasia, and root growth impairment of mandibular third molars were also found. Similar, apparent, radiation-induced developmental anomalies were noted in maxillary third molars of the irradiated patients.

McGinnis, J.P. Jr.; Hopkins, K.P.; Thompson, E.I.; Hustu, H.O.

1987-05-01

288

Effect of bite force on orthodontic mini-implants in the molar region: Finite element analysis  

PubMed Central

Objective To examine the effect of bite force on the displacement and stress distribution of orthodontic mini-implants (OMIs) in the molar region according to placement site, insertion angle, and loading direction. Methods Five finite element models were created using micro-computed tomography (microCT) images of the maxilla and mandible. OMIs were placed at one maxillary and two mandibular positions: between the maxillary second premolar and first molar, between the mandibular second premolar and first molar, and between the mandibular first and second molars. The OMIs were inserted at angles of 45° and 90° to the buccal surface of the cortical bone. A bite force of 25 kg was applied to the 10 occlusal contact points of the second premolar, first molar, and second molar. The loading directions were 0°, 5°, and 10° to the long axis of the tooth. Results With regard to placement site, the displacement and stress were greatest for the OMI placed between the mandibular first molar and second molar, and smallest for the OMI placed between the maxillary second premolar and first molar. In the mandibular molar region, the angled OMI showed slightly less displacement than the OMI placed at 90°. The maximum Von Mises stress increased with the inclination of the loading direction. Conclusions These results suggest that placement of OMIs between the second premolar and first molar at 45° to the cortical bone reduces the effect of bite force on OMIs.

Lee, Hyeon-Jung; Lee, Kyung-Sook; Kim, Min-Ji

2013-01-01

289

Assessment of the relationship between the maxillary molars and adjacent structures using cone beam computed tomography  

PubMed Central

Purpose This study investigated the relationship between the roots of the maxillary molars and the maxillary sinus using cone beam computed tomography (CBCT), and measured the distances between the roots of the maxillary molars and the sinus floor as well as the thickness of the bone between the root and the alveolar cortical plate. Materials and Methods The study sample consisted of 83 patients with normally erupted bilateral maxillary first and second molars. A total of 332 maxillary molars were examined using CBCT images. The vertical relationship of each root with the maxillary sinus was classified into four types on CBCT cross-sectional images. The distance between the sinus floor and root and the bone thickness between the root and alveolar cortical plate were measured. Results In the buccal roots of the maxillary molars, a root protruding into the sinus occurred most frequently. A root projecting laterally along the sinus cavity was most common in the palatal roots of the maxillary first molars. The mesiobuccal roots of the maxillary second molar were closest to the sinus. The mesiobuccal roots of the first molars were closest to the cortical plate. Conclusion The relationship between the roots of the maxillary molars and the sinus differed between the buccal and palatal roots. A root protruding into the sinus occurred more frequent in the buccal roots of the maxillary molars. The mesiobuccal root of the maxillary second molar was closest to the maxillary sinus floor and farthest from the alveolar cortical plate.

Jung, Yun-Hoa

2012-01-01

290

Molar extinction coefficients of some carbohydrates in aqueous solutions  

Microsoft Academic Search

Molar extinction coefficients of some carbohydrates viz. L-arabinose (C5H10O5), D-glucose (C6H12O6), D-mannose (C6H12O6), D-galactose (C6H12O6), D(-) fructose (C6H12O6) and maltose (C12H24O12) in aqueous solutions have been determined at 81, 356, 511, 662, 1173 and 1332 keV by gamma ray transmission method in a narrow beam good geometry set-up. These coefficients have been found to depend upon the photon energy following

K. Singh; G. K. Sandhu; B. S. Lark; S. P. Sud

2002-01-01

291

Molar extinction coefficients of some carbohydrates in aqueous solutions  

Microsoft Academic Search

Molar extinction coefficients of some carbohydrates viz. l-arabinose (C5H10O5), d-glucose (C6H12O6), d-mannose (C6H12O6), d-galactose (C6H12O6), d(-) fructose (C6H12O6) and maltose (C12H24O12) in aqueous solutions have been determined at 81, 356, 511, 662, 1173 and 1332 keV by gamma ray transmission method in a\\u000a narrow beam good geometry set-up. These coefficients have been found to depend upon the photon energy following

K Singh; GK Sandhu; BS Lark; SP Sud

2002-01-01

292

Molar extinction coefficients of some commonly used solvents  

Microsoft Academic Search

Molar extinction coefficients of some commonly used solvents (ethanol (C2H5OH), methanol (CH3OH), propanol (C3H7OH), butanol (C4H9OH), water (H2O), toluene (C7H8), benzene (C6H6), carbontetrachloride (CCl4), acetonitrile (C4H3N), chlorobenzene (C6H5Cl), diethylether (C4H10O) and dioxane (C4H8O2)) have been determined by a well-collimated narrow beam transmission geometry at 279, 356, 662, 1173, 1252 and 1332keV ? rays. The total ? ray interaction cross sections

Ashok Kumar; Sukhpal Singh; Gurmel Singh Mudahar; Kulwant Singh Thind

2006-01-01

293

Molar extinction coefficients of some commonly used solvents  

Microsoft Academic Search

Molar extinction coefficients of some commonly used solvents (ethanol (C2H5OH), methanol (CH3OH), propanol (C3H7OH), butanol (C4H9OH), water (H2O), toluene (C7H8), benzene (C6H6), carbontetrachloride (CCl4), acetonitrile (C4H3N), chlorobenzene (C6H5Cl), diethylether (C4H10O) and dioxane (C4H8O2)) have been determined by a well-collimated narrow beam transmission geometry at 279, 356, 662, 1173, 1252 and 1332 keV gamma rays. The total gamma ray interaction cross

Ashok Kumar; Sukhpal Singh; Gurmel Singh Mudahar; Kulwant Singh Thind

2006-01-01

294

Replantation of a maxillary second molar after removal of a third molar with a dentigerous cyst: Case report and 12-month follow-up  

PubMed Central

The aim of this study was to describe the replantation of a maxillary second right molar, which had been removed for surgical reasons in order to remove a dentigerous cyst associated with the adjacent third molar, and the case’s 12-month follow-up. A 51-year-old man presented swelling in the right maxillary area. Radiographic examination showed a large radiolucency in close proximity to the third molar, suggesting a follicular cyst. The third molar was extracted and the cyst underwent curettage. The second molar had to be extracted to enable complete removal of the cyst and to achieve primary closure of the wound, which would have been impossible without repositioning the molar. With this objective, extraoral endodontic treatment was performed, the root-end was resected and prepared with ultrasonic retrotips, and root-end filling was accomplished with MTA before the molar was replanted. At the 12-month follow-up, the tooth showed no clinical signs or symptoms, probing depth was no greater than 3 mm and radiographic examination showed no evidence of root resorption or periapical lesion. Key words:Replantation, maxillary molar, follicular cyst, dentigerous cyst.

Penarrocha-Diago, Maria A.; Penarrocha-Oltra, David; Penarrocha-Diago, Miguel

2014-01-01

295

Extensive composite molar restorations: 3 years clinical evaluation.  

PubMed

Abstract Objective. To evaluate the clinical performance of extensive direct composite restorations in molars after 1 and 3 years and to find out the importance of extent of the restorations and other factors related to their performance. Materials and methods. Seventy-four patients with a molar tooth in need of a restoration covering at least three surfaces and one cusp were selected. Patient-related factors were registered and the tooth was prepared and restored by using a nano-filled composite. A topographic system for classification of extensive posterior restorations was developed. At baseline, the operator recorded a clinical evaluation, using modified USPHS-criteria. After 1 and 3 years, an independent observer evaluated the restorations. Post-operative problems arising during the observation period were registered. Results. A change in clinical score from baseline to the 1 and 3 year recall was recorded for all clinical criteria. A total of nine restorations were graded as unacceptable after 3 years (3-year survival rate of 87.7% and a mean annual failure rate of 4.2%). Except for gender (p = 0.022), none of the patient-related factors investigated (age, caries risk, extension of the restoration and presence of cervical enamel) had a significant influence on the survival of the restorations. Conclusions. Extensive direct posterior composite restorations showed an acceptable clinical performance after 3 years. Men had a significantly greater restoration failure rate than women. PMID:21780983

Laegreid, Torgils; Gjerdet, Nils Roar; Johansson, Ann-Katrin

2012-07-01

296

Nonlinear Partial Least Squares  

Microsoft Academic Search

Nonlinear Partial Least Squares Edward Carl Malthouse We propose a new nonparametric regression method for high-dimensional data, nonlinear partial least squares (NLPLS). NLPLS is motivated by projection-based regression methods, e.g., partial least squares (PLS), projection pursuit (PPR), and feedforward neural networks. The model takes the form of a composition of two functions. The first function in the composition projects the

Edward Carl Malthouse

1995-01-01

297

Sex determination potential of permanent maxillary molar widths and cusp diameters in a North Indian population  

PubMed Central

Aims: To assess the sex discrimination potential of permanent maxillary molar crown widths and cusp diameters. Materials and Methods: Measurements were made on plaster casts of 200 individuals of known sex (100 males, 100 females, aged 12-21 years). Eight parameters were measured on the first and second maxillary molars with a digital caliper [buccolingual, mesiodistal, mesiobuccal-distolingual and distobuccal-mesiolingual crown widths and cusp diameters (hypocone, protocone, paracone, and metacone)]. The percentage of sexual dimorphism for each parameter was calculated. Discriminant function analysis was used to determine the accuracy of sex determination for each molar separately and both the molars taken together. Results: The highest sexual dimorphism was shown by protocone in the first molar and hypocone in the second molar. Furthermore, the sex determination accuracy was highest when the first molar was taken alone than when the second molar or the first and second molars were taken together. Conclusion: Based on this study, odontometric measurements of maxillary molars provide low to moderate sex determination accuracy.

Sharma, Payal; Singh, Tushita; Kumar, Piush; Chandra, Pavan Kumar; Sharma, Rakesh

2013-01-01

298

An Evidenced Based Scoring System To Determine The Periodontal Prognosis On Molars  

PubMed Central

Background This retrospective study evaluated and assigned scores to six prognostic factors and derived a quantitative scoring system used to determine the periodontal prognosis on molar teeth. Methods Data were gathered on 816 molars in 102 patients with moderate to severe periodontitis. The six factors evaluated, age, probing depth, mobility, furcation involvement, smoking, and molar type, were assigned a numerical score based on statistical analysis. The sum of the scores for all factors was used to determine the prognosis score for each molar. Only patients with all first and second molars at the initial examination qualified for the study. All patients were a minimum of 15 years post treatment. Results The post treatment time ranged from 15 to 40 years and averaged 24 years. When the study was completed, 639 molars survived (78%), and of those surviving molars, 566 survived in health (89%). In molars with lower scores (1,2,and 3) the 15-year survival rates ranged from 99% to 96%. For scores 4, 5, 6 the 15 year survival rates ranged was 95% to 90% and for molars with scores of 7, 8, 9, and 10 the survival rates ranged from 86% to 67%. Conclusions Our results indicate that the periodontal prognosis on molars diagnosed with moderate to severe periodontitis can be calculated using an evidence-based scoring system.

Miller, Preston D.; McEntire, Mark L.; Marlow, Nicole M.; Gellin, Robert G.

2014-01-01

299

Molarity (Aromic Density) of the Elements as Pure Crystals.  

ERIC Educational Resources Information Center

Provides background information for teachers on the atomic density of the elements as pure crystals. Atomic density is defined as the reciprocal of the atomic volume. Includes atomic-density diagrams which were prepared using the atomic-volume values given by Singman, supplemented by additional values for some allotropes. (JN)

Pauling, Linus; Herman, Zelek S.

1985-01-01

300

Periodontal healing after mandibular third molar surgery—A comparison of distolingual alveolectomy and tooth division techniques  

Microsoft Academic Search

The purpose of this study was to compare the periodontal healing of mandibular second molars after the removal of impacted mandibular third molars using distolingual alveolectomy and tooth division techniques. A total of 120 consecutive healthy patients who presented with bilaterally impacted mandibular third molars were included in this study. The same operator removed the impacted third molars on both

H.-H. Chang; J.-J. Lee; S.-H. Kok; P.-J. Yang

2004-01-01

301

[Molar distalization by using vertically installed mini-screws].  

PubMed

Mini-screws can be used for orthodontic anchorage in distalizing maxillary and mandibular molars. With them, practitioners can avoid the undesirable reciprocal movement that so often occurs when teeth are used as anchorage units. In this article, we propose a method of vertical insertion of mini-screws that places them in positions that will not interfere with movement of tooth roots. This allows orthodontists to use mass movements of groups of teeth or even of entire arches, thus reducing the need for extractions, simplifying treatment procedures, and enlarging the range of therapeutic possibilities. We evaluate the indications for this vertical placement in different anatomic situations. We suggest different sites for mini-screw placement and illustrate them with many clinical cases. PMID:23206370

Lee, Ju-Young

2012-12-01

302

[Maxillary first molar with two palatal canals: a case report].  

PubMed

Maxillary first molar with two palatal canals is rare. Clinicians should be aware of the normal anatomy of root canal system and vigilant about the possible existence of canal variation. A patient with acute episode of chronic pulpitis of 26, as presented by the case report, was examined to have four canals, which were the mesial buccal canal, the distal buccal canal, the mesial palatal canal and the distal palatal canal. When suspecting the existence of canal variation, clinicians should carefully explore the pulpal floor, further by changing the X-ray projection angle to confirm the existence of variation and prevent the missed canals, all of which are necessary for a successful root canal therapy. PMID:23852074

Shi, Jian-jun

2013-06-01

303

Molar extinction coefficients of solutions of some organic compounds  

Microsoft Academic Search

Molar extinction coefficients of aqueous solutions of some organic compounds, viz. formamide (CH3NO),N-methylformamide (C2H5NO),NN-dimethylformamide (C3H7NO),NN-dimethylacetamide (C4H9NO), 1,4-dioxane (C4H8O24), succinimide (C4H5NO2) and solutions of acetamide (C2H5NO) and benzoic acid (C7H6O2) in 1,4-dioxane (C4H8O2) have been determined by narrow beam ?-ray transmission method at 81, 356, 511, 662, 1173 and 1332 keV. The experimental\\u000a values of mass attenuation coefficients of these compounds

Kulwant Singh; G. K. Sandhu; B. S. Lark

2004-01-01

304

Molar extinction coefficients of solutions of some organic compounds  

Microsoft Academic Search

Molar extinction coefficients of aqueous solutions of some organic compounds, viz. formamide (CH_{3}NO), N-methylformamide (C_{2}H_{5}NO), NN-dimethylformamide (C_{3}H_{7}NO), NN-dimethylacetamide (C_{4}H_{9}NO), 1,4-dioxane (C_{4}H_{8}O_{2}), succinimide (C_{4}H_{5}NO_{2}) and solutions of acetamide (C_{2}H_{5}NO) and benzoic acid (C_{7}H_{6}O_{2}) in 1,4-dioxane (C_{4}H_{8}O_{2}) have been determined by narrow beam gamma-ray transmission method at 81, 356, 511, 662, 1173 and 1332 keV. The experimental values of mass attenuation coefficients

Kulwant Singh; G. K. Sandhu; B. S. Lark

2004-01-01

305

Molar extinction coefficients of some carbohydrates in aqueous solutions  

NASA Astrophysics Data System (ADS)

Molar extinction coefficients of some carbohydrates viz. L-arabinose (C5H10O5), D-glucose (C6H12O6), D-mannose (C6H12O6), D-galactose (C6H12O6), D(-) fructose (C6H12O6) and maltose (C12H24O12) in aqueous solutions have been determined at 81, 356, 511, 662, 1173 and 1332 keV by gamma ray transmission method in a narrow beam good geometry set-up. These coefficients have been found to depend upon the photon energy following a 4-parameter polynomial. These extinction coefficients for different sugars having the same molecular formula have same values varying within experimental uncertainty. Within concentration ranges studied, Beer--Lambert law is obeyed very well.

Singh, K.; Sandhu, G. K.; Lark, B. S.; Sud, S. P.

2002-03-01

306

Molar extinction coefficients of some commonly used solvents  

NASA Astrophysics Data System (ADS)

Molar extinction coefficients of some commonly used solvents (ethanol (C 2H 5OH), methanol (CH 3OH), propanol (C 3H 7OH), butanol (C 4H 9OH), water (H 2O), toluene (C 7H 8), benzene (C 6H 6), carbontetrachloride (CCl 4), acetonitrile (C 4H 3N), chlorobenzene (C 6H 5Cl), diethylether (C 4H 10O) and dioxane (C 4H 8O 2)) have been determined by a well-collimated narrow beam transmission geometry at 279, 356, 662, 1173, 1252 and 1332 keV ? rays. The total ? ray interaction cross sections of these solvents have also been determined. A good agreement has been obtained between the experimental results with the theoretical values evaluated through XCOM calculations.

Kumar, Ashok; Singh, Sukhpal; Singh Mudahar, Gurmel; Singh Thind, Kulwant

2006-07-01

307

Classification of partial discharges  

Microsoft Academic Search

For a long time, classification of partial discharges was performed by eye, by studying discharge patterns at the ellipse of an oscilloscope screen. The introduction of digital processing techniques allowed automation of the recognition procedure. These procedures are reported and applied to a number of actual HV constructions which suffer from partial discharges. The results of these tests show that

F. H. Kreuger; E. Gulski; A. Krivda

1993-01-01

308

Partial Derivative Visualization Gallery  

NSDL National Science Digital Library

This resource is a small gallery of demos for illustrating partial derivatives geometrically. These animations can be used by instructors in a classroom setting or by students to aid in acquiring a visualization background for partial derivatives. Two file formats, gif and QuickTime files are used for the animations which can be downloaded.

Roberts, Lila F.; Hill, David R.

2004-11-11

309

Fertility preserving treatment in a nulliparous with a molar pregnancy: a case report.  

PubMed

Hydatidiform mole represents an abnormal form of conception that occurs in about one in 500-1000 pregnancies. It is a subtype of gestational trophoblastic disease. Hydatidiform moles should be regarded as premalignant lesions because 15-20% of complete hydatidiform moles (CHMs) and 1% of partial hydatidiform moles (PHMs) undergo malignant transformation into invasive moles, choriocarcinomas, or, in rare cases, placental-site trophoblastic tumors (PSTTs). We will illustrate the case of a 26-year-old nulliparous with a seven weeks amenorrhea, positive immunological pregnancy test, a ?-HCG value of 136 000 mIU÷mL and minor vaginal bleeding. The ultrasonographic examination showed an enlarged endometrium with adjacent hyperechoic material containing tiny anechoic spaces and an anembryonic pregnancy, distended endometrial cavity containing innumerable, variably sized anechoic cysts with intervening hyperechoic material ("snowstorm" appearance). The CT showed a uterine mass measuring 89÷111÷67 mm, inhomogeneous density, proliferative-infiltrative endocavitary tissue without exceeding the peritoneal serosa, and a few pulmonary micronodules with not certain origin on the left inferior lobe. In this case, due to the large infiltrative uterine mass, the risk of severe bleeding after curettage and the possibility of a necessity hysterectomy, we decided to apply first of all the Methotrexate protocol for molar pregnancy. PMID:24970000

Filipescu, George Alexandru; Boiangiu, Andreea Gratiana; Clim, Nicoleta; Andrei, Florin

2014-01-01

310

Mineral trioxide aggregate as a pulpotomy agent in primary molars: an in vivo study.  

PubMed

The retention of pulpally involved deciduous tooth in a healthy state until the time of normal exfoliation remains to be one of the challenges for Pedodontists. A scientific noise has been generated about several materials some of which have been popular pulpotomy medicaments. Concerns have been raised about the toxicity and potential carcinogenicity of these materials, and alternatives have been proposed to maintain the partial pulp vitality, however to date no material has been accepted as an ideal pulpotomy agent. Mineral trioxide aggregate (MTA) is a biocompatible material which provides a biological seal. MTA has been proposed as a potential medicament for various pulpal procedures like pulp capping with reversible pulpitis, apexification, repair of root perforations, etc. Hence the present study was done to evaluate the efficacy of MTA as a pulpotomy medicament. A clinical and radiographic evaluation was done on children where MTA was used as pulpotomy medicament in primary molars for a period of 6 months and it was found to be a successful material. PMID:15858300

Naik, S; Hegde, A H

2005-03-01

311

Indirect pulp therapy in a symptomatic mature molar using calcium enriched mixture cement.  

PubMed

Dental pulp has the ability of repair/regeneration. Indirect pulp therapy (IPT) is recommended for pulp preservation in asymptomatic teeth with extremely deep caries as well as teeth with clinical symptoms of reversible pulpitis. In this case study, we performed IPT with calcium enriched mixture (CEM) cement on a symptomatic permanent molar. After clinical/radiographic examinations the tooth was diagnosed with irreversible pulpitis and associated apical periodontitis. IPT involved partial caries removal, the placement of CEM cement pulp cap and overlying adhesive permanent restoration. At the 1 week follow-up, patient's spontaneous symptoms had resolved. One-year follow-up demonstrated pulp vitality, clinical function, as well as the absence of pain/tenderness to percussion/palpation/cold sensitivity tests; periapical radiograph showed a healing periradicular lesion with newly formed bone, that is normal pulp with normal periodontium. These favorable results indicate that IPT/CEM may be a good treatment option in comparison to endodontic treatment in young patients. IPT of deep-caries lesion is an easier, more practical and valuable treatment plan than complete caries removal. PMID:23349584

Torabzadeh, Hassan; Asgary, Saeed

2013-01-01

312

Indirect pulp therapy in a symptomatic mature molar using calcium enriched mixture cement  

PubMed Central

Dental pulp has the ability of repair/regeneration. Indirect pulp therapy (IPT) is recommended for pulp preservation in asymptomatic teeth with extremely deep caries as well as teeth with clinical symptoms of reversible pulpitis. In this case study, we performed IPT with calcium enriched mixture (CEM) cement on a symptomatic permanent molar. After clinical/radiographic examinations the tooth was diagnosed with irreversible pulpitis and associated apical periodontitis. IPT involved partial caries removal, the placement of CEM cement pulp cap and overlying adhesive permanent restoration. At the 1 week follow-up, patient's spontaneous symptoms had resolved. One-year follow-up demonstrated pulp vitality, clinical function, as well as the absence of pain/tenderness to percussion/palpation/cold sensitivity tests; periapical radiograph showed a healing periradicular lesion with newly formed bone, that is normal pulp with normal periodontium. These favorable results indicate that IPT/CEM may be a good treatment option in comparison to endodontic treatment in young patients. IPT of deep-caries lesion is an easier, more practical and valuable treatment plan than complete caries removal.

Torabzadeh, Hassan; Asgary, Saeed

2013-01-01

313

Quantification of chlorinated naphthalenes with GC-MS using the molar response of electron impact ionization  

Microsoft Academic Search

The concept of the molar response (MR) in HRGC\\/EI-MS has been checked for naphthalene and three chlorinated naphthalenes: 1-chloronaphthalene, 1,2,3,4-tetrachloronaphthalene and octachloronaphthalene. The molar response factors increase with increasing degree of chlorination. When the ion yield is normalized for the ionization cross section Q of the molecule, a constant value of injected molar mass to signal intensity is obtained for

Thomas Wiedmann; Karlheinz Ballschmiter

1993-01-01

314

Application of size-exclusion chromatography to polymers of ultra-high molar mass  

Microsoft Academic Search

This article describes the experimental conditions that should be applied to avoid molecular degradation in size-exclusion chromatography of polymers of ultra-high molar mass (weight-average molar mass Mw>5000 kg\\/mol). The applicability of the optimized experimental conditions is demonstrated using polystyrene as a model substance, but also by using polymers of biochemical and biophysical interest, such as polyethylene of ultra-high molar mass,

Nicolai Aust

2003-01-01

315

Submandibular-space abscess from loss of a bonded molar tube during orthognathic surgery.  

PubMed

The use of bonded orthodontic molar tubes is becoming more prevalent in orthodontics because they have some advantages over conventional bonding. However, a bonded apparatus can become detached, leading to complications. This article presents the case of a submandibular-space abscess associated with a molar tube that detached during orthognathic surgery and became embedded in the soft tissues. The site became infected, and antibiotics were prescribed. Eventually, the molar tube migrated and could be removed under local anesthesia. PMID:23631975

de Queiroz, Sormani Bento Fernandes; Curioso, Pedro Augusto Bulhões; Carvalho, Francisco Samuel Rodrigues; de Lima, Valthierre Nunes

2013-05-01

316

[Role of lower third molars in the development of dental malocclusion: review of the literature].  

PubMed

The Author's aims was to review the role of the lower third molars in delayed crowding of the jaw. A global agreement exists on the fact that lower molars should be considered only one between several factors able to cause malocclusion. Finally, the germectomy of the third molars has to be performed only in carefully selected patients after a comprehensive diagnostic evaluation of the single case. PMID:2205795

Garattini, G; Grecchi, M T; Vogel, G

1990-01-01

317

Automatic Molar Extraction from Dental Panoramic Radiographs for Forensic Personal Identification  

NASA Astrophysics Data System (ADS)

Measurement of an individual molar provides rich information for forensic personal identification. We propose a computer-based system for extracting an individual molar from dental panoramic radiographs. A molar is obtained by extracting the region-of-interest, separating the maxilla and mandible, and extracting the boundaries between teeth. The proposed system is almost fully automatic; all that the user has to do is clicking three points on the boundary between the maxilla and the mandible.

Samopa, Febriliyan; Asano, Akira; Taguchi, Akira

318

An unusual occurrence of bilaterally geminated mandibular second premolars resulting in premolar molarization: A case report.  

PubMed

Gemination refers to an attempt by a single tooth bud to divide, with a resultant formation of either a large tooth with a bifid crown or two completely divided teeth throughout the crown and root. This report describes a rare case of bilateral gemination of permanent mandibular second premolar tooth giving rise to molarization of premolars. The mesiodistal width of these teeth is similar to mandibular molars, but the cervicoocclusal width is lesser than that of the molar tooth. This paper also discusses the potential orthodontic, periodontal, and endodontic complications of premolar molarization. PMID:24347900

Rajesh Ebenezar, Av; Venkatesh, A; Mary, A Vinita; Mohan, Ajit George

2013-11-01

319

An unusual occurrence of bilaterally geminated mandibular second premolars resulting in premolar molarization: A case report  

PubMed Central

Gemination refers to an attempt by a single tooth bud to divide, with a resultant formation of either a large tooth with a bifid crown or two completely divided teeth throughout the crown and root. This report describes a rare case of bilateral gemination of permanent mandibular second premolar tooth giving rise to molarization of premolars. The mesiodistal width of these teeth is similar to mandibular molars, but the cervicoocclusal width is lesser than that of the molar tooth. This paper also discusses the potential orthodontic, periodontal, and endodontic complications of premolar molarization.

Rajesh Ebenezar, AV; Venkatesh, A; Mary, A Vinita; Mohan, Ajit George

2013-01-01

320

Upscaling of hydraulic conductivity in partially saturated heterogeneous porous formation  

Microsoft Academic Search

This paper describes a procedure to upscale unsaturated hydraulic conductivity from the scale at which it is measured to a scale more amenable to actual flow simulations in partially saturated heterogeneous porous formations. In the approach adopted here the block conductivity is defined as the ratio of volume-averaged flux to the volume-averaged head gradient. The “point” values of the underlying

David Russo

1992-01-01

321

Immediate function of partial fixed rehabilitation with axial and tilted implants having intrasinus insertion.  

PubMed

Implant-supported rehabilitation of the posterior maxilla could be challenging because hyperpneumatization of the maxillary sinus might reduce the bone height. In this study, the authors report preliminary results of a new treatment modality for the partial fixed rehabilitation of posterior maxilla with immediate function by using 1 anterior axial implant and 1 posterior tilted implant with intrasinus mesial insertion. From 2009 to 2011, 10 patients (6 women and 4 men) with missing upper premolars and molars were recruited and treated according to this protocol. Each patient received a partial fixed bridge supported by 1 axial anterior implant and 1 posterior implant placed with a 30-degree mesial inclination and intrasinus insertion. Autologous bone was positioned to fill the maxillary sinus cavity and to cover the exposed implant surface after elevation of the anterior sinus membrane. A prosthesis with immediate function was positioned within 3 hours, whereas a CAD/CAM final restoration was delivered 6 months later. Follow-ups at 6 and 12 months, and then annually, were scheduled. At each follow-up, plaque level and bleeding scores were assessed, and radiographic evaluation of marginal bone level change was performed at 1 year. The patients were followed up for a mean of 50 months (range, 42-57 mo). No implants were lost, and all prostheses were stable and functional, reporting 100% of implant and prosthetic success rates. After 1 year, bone loss had a mean (SD) of 1.0 (0.4) and 0.9 (0.5) mm for axial and tilted implants, respectively, with no statistically significant differences between them (P > 0.05). The preliminary results suggest that this approach could allow the rehabilitation of posterior maxilla with immediate function in case of reduced bone volume, representing an alternative technique to bone grafting, short implants, and zygomatic or pterygoid implants. PMID:24820712

Agliardi, Enrico Luigi; Tetè, Stefano; Romeo, Davide; Malchiodi, Luciano; Gherlone, Enrico

2014-05-01

322

Partially coherent lensfree tomographic microscopy?  

PubMed Central

Optical sectioning of biological specimens provides detailed volumetric information regarding their internal structure. To provide a complementary approach to existing three-dimensional (3D) microscopy modalities, we have recently demonstrated lensfree optical tomography that offers high-throughput imaging within a compact and simple platform. In this approach, in-line holograms of objects at different angles of partially coherent illumination are recorded using a digital sensor-array, which enables computing pixel super-resolved tomographic images of the specimen. This imaging modality, which forms the focus of this review, offers micrometer-scale 3D resolution over large imaging volumes of, for example, 10–15 mm3, and can be assembled in light weight and compact architectures. Therefore, lensfree optical tomography might be particularly useful for lab-on-a-chip applications as well as for microscopy needs in resource-limited settings.

Isikman, Serhan O.; Bishara, Waheb; Ozcan, Aydogan

2012-01-01

323

Clinical evaluation of chemomechanical caries removal in primary molars and its acceptance by patients.  

PubMed

The purpose of this study was to evaluate the clinical efficiency and patient acceptance of the chemomechanical caries removal agent Carisolvtrade mark in deciduous teeth. Contralateral primary molars of sixteen 7- to 9-year-old patients (32 teeth) were treated with the air-motor and with Carisolv, respectively. Patients replied to a pre- and a postoperative questionnaire. Complete caries removal (CCR) was accomplished in all air-motor sessions. It was not achieved within the time limit of 15 min in 6 (37.5%) Carisolv sessions. Air-motor CCR time ranged between 6 and 18 s (mean: 11.81 s ). Carisolv CCR time, where accomplished within 15 min, ranged between 6 min 46 s and 13 min 57 s (mean: 6 min 51 s). Preoperatively, the majority of the children reported disliking the drilling, and that they would visit the dentist more often and prefer sitting in the chair longer if they could avoid it. Postoperatively, the majority of the children reported disliking the taste of Carisolv, estimated Carisolv to have taken longer, would not recommend it to their friends, and preferred the air-motor. In conclusion, Carisolv, although a step forward in terms of solution volume required, is not in a position to replace rotary instruments for caries removal: it did not remove decay completely in one third of our sample; it was much slower than the air-motor; it had a chlorine taste/odor our patients disliked. PMID:11385201

Maragakis, G M; Hahn, P; Hellwig, E

2001-01-01

324

Changes in periodontal pulsation in relation to increasing loads on rat molars and to blood pressure.  

PubMed

Pulsation originating from the vascular system of the periodontal ligament (PDL) is apparently synchronized with the heartbeat. As periodontal pulsation causes pulsatile tooth vibration, it might be possible to evaluate it indirectly by measuring tooth vibration. Periodontal pulsation has been found to be dependent on blood flow and blood pressure in the PDL. Heavy orthodontic force is known to reduce blood flow and decrease the amplitude of the pulsation. The purpose now was to examine (1). the magnitude of the experimental orthodontic force that will impair PDL blood flow; and (2). the differences in the amplitude of pulsation between normal and hypertensive animals. The experiments were performed on 10 Wistar, 10 Dahl S and 10 Dahl R rats. Hypertension was induced in Dahl S rats. The head and maxilla of anaesthetized animals were immobilized. Mesial tipping forces of different loads (0.098-0.882 N) were applied to a molar and periodontal pulsation was measured with a highly sensitive laser displacement meter. The periodontal pulsation at each load resembled a blood-volume pulse wave. Its amplitude began to decrease at a load of 0.588 N in Wistar and Dahl R rats, and at 0.784 N in Dahl S rats. The group with induced hypertension had a significantly larger amplitude than the other two groups when 0.588 N was applied. These results suggest that: (1). periodontal pulsation can indicate a PDL overload; and (2). that systemic blood pressure affects the amplitude of periodontal pulsation during loading. PMID:12221017

Imamura, Nobuyoshi; Nakata, Shunsuke; Nakasima, Akihiko

2002-08-01

325

Volumes of mixing and the isomeric effect. Part I. Nonane Isomers with n -nonane and n -hexadecane  

Microsoft Academic Search

Molar excess volumes of four nonane isomers mixed with n-nonane and n-hexadecane were obtained from precise density measurements over the complete mole fraction range at 25°C. Good agreement was found between the experimental molar excess volumes and those predicted by the Flory theory. This work shows the importance of the three contributions to Vme, the heat of mixing X12, the

Akl M. Awwad; Etamed I. Allos

1987-01-01

326

The influence of impaction to the third molar mineralization in northwestern Chinese population.  

PubMed

Age estimation by third molar mineralization has been developed for a period of time. Recent studies showed that impaction status has an influence on the rate of the third molar mineralization in Europids and male Black African populations. In this regard, the present study was conducted to determine whether the impaction status could delay the chronological process of third molar mineralization in northwestern Chinese population too. A total of 3,512 digital orthopantomograms of 1,255 male and 2,257 female northwestern Chinese subjects aged from 11 to 26 years were assessed based on the formation stages described by Demirjian et al. with two modifications. Mineralization stage and impaction status were determined for all third molars. Statistical measures were calculated at stages C-H in the male and female gender for both impacted and non-impacted third molars. It was ascertained that the mean ages with impacted third molars at stages C-H were 0.02-1.42 years higher in males and 0.04-1.52 years higher in females than those with non-impacted third molars, but statistical differences were only found at stages C, D, and E in males and stages D and E in females. The probabilities of being under 14, 16, or 18 years of age with non-impacted third molars were all higher than those with impacted third molars. The results prove that impacted third molars show significant slower mineralization than non-impacted ones at stages D and E in both males and females of northwestern Chinese population. It is recommended to consider the influence of impaction on the rate of third molar mineralization for dental age estimation. PMID:24532176

Guo, Yu-cheng; Yan, Chun-xia; Lin, Xing-wei; Zhang, Wen-tao; Zhou, Hong; Pan, Feng; Wei, Lai; Tang, Zheng; Liang, Feng; Chen, Teng

2014-07-01

327

Partial Testing Design  

Cancer.gov

Statistical Software Partial Testing Design (Written by Stuart G. Baker) New Approach (with ROC curves): See Baker SG, Pinsky P. A proposed design and analysis for comparing digital and analog mammography: special ROC methods for cancer screening. JASA.

328

Partial Derivatives: Geometric Visualization  

NSDL National Science Digital Library

This write-pair-share activity presents Calculus III students with a worksheet containing several exercises that require them to find partial derivatives of functions of two variables. Afterwards, a series of Web-based animations are used to illustrate the surface of each function, the path of the indicated partial derivative for a specified value of the variable and the value of the derivative at each point along the path.

Rutledge, James

329

Partial Rotator Cuff Ruptures  

Microsoft Academic Search

\\u000a Partial rotator cuff ruptures are not rare and occur mainly in the supraspinatus tendon and may extend to that of infraspinatus,\\u000a but rarely to the tendon of subscapularis. Isolated lesions in the tendons of infraspinatus, teres minor or subscapularis\\u000a are rare. Partial ruptures usually occur before the sixth decade of life and can be a cause of unexplained pain in

Antonio Cartucho

330

Partially saponified triglyceride ethoxylates  

Microsoft Academic Search

Various triglycerides (coconut oil, palm kernel oil, tallow) were ethoxylated with a proprietary catalyst (calcium\\/aluminum\\u000a alkoxide complex partially neutralized in an alcohol ethoxylate base) to obtain triglyceride ethoxylates. Triglyceride ethoxylates\\u000a were then partially saponified with sodium hydroxide to form mixtures of mono-, di-, and triglyceride ethoxylates, fatty acid\\u000a soap, and glycerol ethoxylate. These mixtures were characterized in terms of physical

Michael F. Cox; Upali Weerassoriya

2000-01-01

331

PARTIAL TORUS INSTABILITY  

SciTech Connect

Flux ropes are now generally accepted to be the magnetic configuration of coronal mass ejections (CMEs), which may be formed prior to or during solar eruptions. In this study, we model the flux rope as a current-carrying partial torus loop with its two footpoints anchored in the photosphere, and investigate its stability in the context of the torus instability (TI). Previous studies on TI have focused on the configuration of a circular torus and revealed the existence of a critical decay index of the overlying constraining magnetic field. Our study reveals that the critical index is a function of the fractional number of the partial torus, defined by the ratio between the arc length of the partial torus above the photosphere and the circumference of a circular torus of equal radius. We refer to this finding as the partial torus instability (PTI). It is found that a partial torus with a smaller fractional number has a smaller critical index, thus requiring a more gradually decreasing magnetic field to stabilize the flux rope. On the other hand, a partial torus with a larger fractional number has a larger critical index. In the limit of a circular torus when the fractional number approaches 1, the critical index goes to a maximum value. We demonstrate that the PTI helps us to understand the confinement, growth, and eventual eruption of a flux-rope CME.

Olmedo, Oscar; Zhang Jie, E-mail: oolmedo@gmu.ed [Department of Computational and Data Sciences, George Mason University, 4400 University Drive, Fairfax, VA 22030 (United States)

2010-07-20

332

Electro-acupuncture efficacy on pain control after mandibular third molar surgery  

Microsoft Academic Search

The aim of this study was to evaluate the efficacy of electro-acupuncture (EAC) on postoperative pain control after mandibular third molar surgery. Twenty four young patients (12 male and 12 female) with symmetrically impacted mandibular third molars were selected. Each patient was submitted to two separate surgical procedures under local anesthesia. At one side, extraction was carried out employing both

Marconi Gonzaga Tavares; Ana Paula Machado; Breno Gutierrez Motta; Maria Cristina Borsatto; Adalberto Luiz Rosa; Samuel Porfírio Xavier

2007-01-01

333

Comparison of mineral trioxide aggregate and formocresol as pulp medicaments for pulpotomies in primary molars  

Microsoft Academic Search

Purpose The aim of this study was to compare the effect of white mineral trioxide aggregate (MTA) to that of formocresol (FC) as pulp dressing agents in pulpotomised primary molars.Methods In this clinical trial study, 60 lower second primary molars of 46 children were treated by a conventional pulpotomy technique. The teeth were randomly assigned to the MTA (experimental) and

H. Noorollahian

2008-01-01

334

Long-term Evaluation of Pulpotomy in Primary Molars Using Mineral Trioxide Aggregate or Formocresol  

Microsoft Academic Search

Purpose. The objective of this study was to assess the effect of mineral trioxide aggre- gate (MTA) as pulp dressing material following pulpotomy in primary molars with carious pulp exposure and compare them to those of formocresol (FC). Methods. Of 33 children, primary molars treated via a conventional pulpotomy tech- nique were randomly assigned to the MTA group (33 teeth)

Gideon Holan; Eliezer Eidelman; Anna B. Fuks

2005-01-01

335

A Comparison of Four Pulpotomy Techniques in Primary Molars: A Long-term Follow-up  

Microsoft Academic Search

The study evaluated the effects of formocresol (FC), ferric sulphate (FS), calcium hydroxide (Ca[OH]2), and mineral trioxide aggregate (MTA) as pulp dressing agents in pulpotomized primary molars. Sixteen children each with at least four primary molars requiring pulpotomy were selected. Eighty selected teeth were divided into four groups and treated with one of the pulpotomy agent. The children were recalled

Deniz Sonmez; Saziye Sari; Tu?ba Çetinba?

2008-01-01

336

Mineral trioxide aggregate vs. formocresol in pulpotomized primary molars: a preliminary report  

Microsoft Academic Search

Purpose: The aim of this study was to compare the effect of mineral trioxide aggregate (MTA) to that of formocresol (FC) as pulp dressing agents in pulpotomized primary molars with cari- ous pulp exposure. Methods: Forty-five primary molars of 26 children were treated by a conventional pulpotomy technique. The teeth were randomly assigned to the MTA (experimental) or FC (control)

Eliezer Eidelman; Anna B. Fuks

2001-01-01

337

Maxillary tuberosity fracture associated with first molar extraction: a case report.  

PubMed

Maxillary tuberosity fractures during molar teeth extraction can occur commonly in dental practice; however, very few cases are reported and discussed in the literature. This article presents a case of large fracture of maxillary tuberosity during extraction of first maxillary molar tooth and its conservative treatment outcomes. PMID:19212477

Polat, Hidayet B; Ay, Sinan; Kara, M Isa

2007-10-01

338

Uniquely derived upper molar morphology of Eocene Amphipithecidae (Primates: Anthropoidea): homology and phylogeny.  

PubMed

The extinct Southeast Asian primate family Amphipithecidae is regularly cited in discussions of anthropoid origins, but its phylogenetic position remains controversial. In part, the lack of consensus regarding amphipithecid relationships can be attributed to uncertainty regarding the homology of upper molar structures in this group. Here, we describe a virtually pristine upper molar of Pondaungia cotteri from the late middle Eocene Pondaung Formation of Myanmar, which is the first example of a relatively unworn and well-preserved amphipithecid upper molar ever recovered. The distolingual upper molar cusp in this new specimen of Pondaungia appears to be a lingually displaced and enlarged metaconule, rather than a hypocone or pseudohypocone as previous workers have thought. Reassessment of the upper molar morphology of other amphipithecids and putative amphipithecids reveals a very similar pattern in Siamopithecus, Myanmarpithecus and Ganlea, all of which are interpreted as having upper molars showing many of the same derived features apparent in Pondaungia. In contrast, the upper molar morphology of Bugtipithecus diverges radically from that of undoubted amphipithecids, and the latter taxon is excluded from Amphipithecidae on this basis. Phylogenetic analyses of several character-taxon matrices culled from the recent literature and updated to reflect the new information on amphipithecid upper molar morphology yield similar results. Consensus tree topologies derived from these analyses support amphipithecid monophyly and stable relationships within Amphipithecidae. Amphipithecids appear to be stem members of the anthropoid clade. PMID:23823753

Coster, Pauline; Beard, K Christopher; Soe, Aung Naing; Sein, Chit; Chaimanee, Yaowalak; Lazzari, Vincent; Valentin, Xavier; Jaeger, Jean-Jacques

2013-08-01

339

Experience versus complication rate in third molar surgery  

PubMed Central

Objectives The records of 1087 patients who underwent surgical removal of third molar teeth were prospectively examined to analyse the possible relationship between postoperative complications and the surgeon's experience parameter. Method and materials Seven surgeons (three specialists in surgical dentistry [specialists SD] and four oral and maxillofacial Senior House Officers [OMFS residents]) carried out the surgical procedures. For each patient, several variables were recorded including age, gender, radiographic position of extracted teeth, treating surgeon, duration of surgery and postoperative complications. Results Analysis of the data revealed some differences in the incidence of complications produced by the specialists SD and OMFS residents. The main statistically relevant differences were increase the incidences of trismus, nerve paraesthesia, alveolar osteitis and infection in the resident-treated group, while the specialist-treated group showed higher rates of post-operative bleeding. Conclusion The higher rate of postoperative complications in the resident-treated group suggests that at least some of the complications might be related to surgical experience. Further work needs to compare specialists of training programmes with different years of experience, using large cross – sectional studies.

Jerjes, Waseem; El-Maaytah, Mohammed; Swinson, Brian; Banu, Bilquis; Upile, Tahwinder; D'Sa, Sapna; Al-Khawalde, Mohammed; Chaib, Boussad; Hopper, Colin

2006-01-01

340

Lingual nerve protection during surgical removal of lower third molars. a prospective randomised study.  

PubMed

A prospective randomised study was designed to evaluate the efficacy of protecting the lingual nerve by subperiosteal insertion of a retractor in 300 patients. All operations were performed under local anaesthesia and only one molar was removed at a time. In one group, the lower third molar was removed with protection of the lingual nerve and in another group, without protection. Molars which did not need to be sectioned were excluded from the study. The position of the molar, the degree of surgical difficulty and patient gender and age were also recorded. The results indicate 1.33% incidence of temporary lingual nerve dysaesthesia--this being low in comparison with other studies. No permanent disturbances were found. The intergroup percentage difference was not significant. It is suggested that routine application of a lingual protecting instrument during surgical removal of a third molar is not necessary in the hands of an experienced surgeon. PMID:11030397

Gargallo-Albiol, J; Buenechea-Imaz, R; Gay-Escoda, C

2000-08-01

341

A new type of dental anomaly: molar-incisor malformation (MIM).  

PubMed

A molar-incisor malformation (MIM) is a newly discovered type of dental anomaly of the permanent first molars, deciduous second molars, and permanent maxillary central incisors. MIM anomalies of the permanent first molars and deciduous second molars may include normal crowns with a constricted cervical region and thin, narrow, and short roots, whereas the affected maxillary central incisors may exhibit a hypoplastic enamel notch near the cervical third of the clinical crown. Although the etiology of MIM remains to be determined, it is thought to be attributable to an epigenetic factor linked to brain- and central nervous system-related systemic diseases at around age 1 to 2 years. MIM teeth are associated with clinical problems such as impaction, early exfoliation, space loss, spontaneous pain, periapical abscess, and poor incisor esthetics. Children with MIM teeth should be observed closely with respect to their medical history, and dentists should formulate a wider-ranging treatment plan. PMID:24908600

Lee, Hyo-Seol; Kim, Soo-Hyun; Kim, Seong-Oh; Lee, Jae-Ho; Choi, Hyung-Jun; Jung, Han-Sung; Song, Je Seon

2014-07-01

342

Partially Pumped Random Lasers  

NASA Astrophysics Data System (ADS)

Conventional lasers consist of two components: a gain material that is pumped in order to provide amplification of light and a cavity to provide feedback. Random lasers replace the traditional laser cavity with a random, multiple-scattering medium. This can give rise to complex lasing behavior, such as unpredictable multidirectional and multifrequency output. Controlling these systems has proved difficult and, until now, has consisted of material and structural manipulations. In random lasers, the most common pumping mechanism is an optical field, which can be applied uniformly or partially across the scattering medium. Partial pumping, referring to the restricted spatial extent of the pump applied to the gain material, is therefore quite ubiquitous in such systems. In contrast to conventional lasers, however, the impact of partial pumping can be significant in random lasers as a subset of the scattering medium is probed. In this review, we discuss state-of-the-art investigations of partially pumped random lasers. Numerical and experimental investigations of how even a simple spot profile of the pump can dramatically alter random laser output are presented. First, the simple case of partial pumping in strongly scattering systems where laser modes are spatially confined is described. Then the most common but more difficult case of weakly scattering random lasers is considered. Here, modes are spatially extended, forcing greater mode interaction and making the random laser output more difficult to predict. Finally, we review recent works that show how the pumping degree of freedom allows a general increase in control over random lasers.

Andreasen, Jonathan; Bachelard, Nicolas; Bhaktha, Shivakiran B. N.; Cao, Hui; Sebbah, Patrick; Vanneste, Christian

2014-02-01

343

Partial spread OFDM  

NASA Astrophysics Data System (ADS)

In this paper, partial spread OFDM system has been presented and its performance has been studied when different detection techniques are employed, such as minimum mean square error (MMSE), grouped Maximum Likelihood (ML) and approximated integer quadratic programming (IQP) techniques . The performance study also includes applying two different spreading matrices, Hadamard and Vandermonde. Extensive computer simulation have been implemented and important results show that partial spread OFDM system improves the BER performance and the frequency diversity of OFDM compared to both non spread and full spread systems. The results from this paper also show that partial spreading technique combined with suboptimal detector could be a better solution for applications that require low receiver complexity and high information detectability.

Elghariani, Ali; Zoltowski, Michael D.

2012-05-01

344

Oxygen partial pressure sensor  

DOEpatents

A method for detecting oxygen partial pressure and an oxygen partial pressure sensor are provided. The method for measuring oxygen partial pressure includes contacting oxygen to a solid oxide electrolyte and measuring the subsequent change in electrical conductivity of the solid oxide electrolyte. A solid oxide electrolyte is utilized that contacts both a porous electrode and a nonporous electrode. The electrical conductivity of the solid oxide electrolyte is affected when oxygen from an exhaust stream permeates through the porous electrode to establish an equilibrium of oxygen anions in the electrolyte, thereby displacing electrons throughout the electrolyte to form an electron gradient. By adapting the two electrodes to sense a voltage potential between them, the change in electrolyte conductivity due to oxygen presence can be measured.

Dees, Dennis W. (Downers Grove, IL)

1994-01-01

345

Oxygen partial pressure sensor  

DOEpatents

A method for detecting oxygen partial pressure and an oxygen partial pressure sensor are provided. The method for measuring oxygen partial pressure includes contacting oxygen to a solid oxide electrolyte and measuring the subsequent change in electrical conductivity of the solid oxide electrolyte. A solid oxide electrolyte is utilized that contacts both a porous electrode and a nonporous electrode. The electrical conductivity of the solid oxide electrolyte is affected when oxygen from an exhaust stream permeates through the porous electrode to establish an equilibrium of oxygen anions in the electrolyte, thereby displacing electrons throughout the electrolyte to form an electron gradient. By adapting the two electrodes to sense a voltage potential between them, the change in electrolyte conductivity due to oxygen presence can be measured. 1 fig.

Dees, D.W.

1994-09-06

346

Methanol partial oxidation reformer  

DOEpatents

A partial oxidation reformer is described comprising a longitudinally extending chamber having a methanol, water and an air inlet and an outlet. An igniter mechanism is near the inlets for igniting a mixture of methanol and air, while a partial oxidation catalyst in the chamber is spaced from the inlets and converts methanol and oxygen to carbon dioxide and hydrogen. Controlling the oxygen to methanol mole ratio provides continuous slightly exothermic partial oxidation reactions of methanol and air producing hydrogen gas. The liquid is preferably injected in droplets having diameters less than 100 micrometers. The reformer is useful in a propulsion system for a vehicle which supplies a hydrogen-containing gas to the negative electrode of a fuel cell. 7 figs.

Ahmed, S.; Kumar, R.; Krumpelt, M.

1999-08-17

347

Methanol partial oxidation reformer  

DOEpatents

A partial oxidation reformer is described comprising a longitudinally extending chamber having a methanol, water and an air inlet and an outlet. An igniter mechanism is near the inlets for igniting a mixture of methanol and air, while a partial oxidation catalyst in the chamber is spaced from the inlets and converts methanol and oxygen to carbon dioxide and hydrogen. Controlling the oxygen to methanol mole ratio provides continuous slightly exothermic partial oxidation reactions of methanol and air producing hydrogen gas. The liquid is preferably injected in droplets having diameters less than 100 micrometers. The reformer is useful in a propulsion system for a vehicle which supplies a hydrogen-containing gas to the negative electrode of a fuel cell. 7 figs.

Ahmed, S.; Kumar, R.; Krumpelt, M.

1999-08-24

348

Dynamics of partial control  

NASA Astrophysics Data System (ADS)

Safe sets are a basic ingredient in the strategy of partial control of chaotic systems. Recently we have found an algorithm, the sculpting algorithm, which allows us to construct them, when they exist. Here we define another type of set, an asymptotic safe set, to which trajectories are attracted asymptotically when the partial control strategy is applied. We apply all these ideas to a specific example of a Duffing oscillator showing the geometry of these sets in phase space. The software for creating all the figures appearing in this paper is available as supplementary material.

Sabuco, Juan; Sanjuán, Miguel A. F.; Yorke, James A.

2012-12-01

349

Dynamics of partial control.  

PubMed

Safe sets are a basic ingredient in the strategy of partial control of chaotic systems. Recently we have found an algorithm, the sculpting algorithm, which allows us to construct them, when they exist. Here we define another type of set, an asymptotic safe set, to which trajectories are attracted asymptotically when the partial control strategy is applied. We apply all these ideas to a specific example of a Duffing oscillator showing the geometry of these sets in phase space. The software for creating all the figures appearing in this paper is available as supplementary material. PMID:23278093

Sabuco, Juan; Sanjuán, Miguel A F; Yorke, James A

2012-12-01

350

Use of cone beam imaging to assess inter-root distance in molar furcations.  

PubMed

This study used cone beam computed tomography (CBCT) to evaluate distances among root surfaces in molar furcations and assess the congruence between inter-root distances in molar furcations and curette blade widths. Distances among root surfaces at 1 and 3 mm from the fornix of molar furcations (points A and B, respectively) were measured with standardized CBCT images and analyzed using computer software. Periodontal curette widths were evaluated by digital caliper and stereomicroscope (magnification 10x). Forty CBCT images (containing a total of 141 molar teeth and 354 furcations) were evaluated; 19 furcations (5.4%) with fused molars were excluded. Mesial furcations of the first molars had the highest average inter-root distances (point A: 3.81 ± 0.87 mm; point B: 5.30 ± 0.92 mm), while buccal furcations of the maxillary second molars had the smallest average distances (point A: 1.49 ± 0.37 mm; point B: 1.90 ± 0.65 mm). Analysis of 107 curettes revealed statistically significant differences among curette types and manufacturers. Pearson's coefficient revealed a strong and significant correlation for curette measurement using digital caliper and stereomicroscope (r = 0.86, P < 0.01). In most cases, the curettes tested allowed access for scaling and root planing of teeth with furcation involvement. PMID:24598502

Dutra, Danilo Antonio Milbradt; da Silva, Felipe Borges; Moreira, Carlos Heitor Cunha; Kantorski, Karla Zanini

2014-01-01

351

Autogenous transplantation of mandibular third molar to replace tooth with vertical root fracture  

PubMed Central

Autogenous tooth transplantation (ATT) can be considered when there is a hopeless molar tooth and suitable donor present. This report presents an unconventional case of successful ATT of a third molar replacing the adjacent fractured second molar in a 33 year old woman. This wisdom tooth had completely developed roots. Root-end filling with Calcium Enriched Mixture (CEM) cement was performed in the third molar. The second molar was extracted non-traumatically without any bone removal; the wisdom tooth was immediately transplanted into the recipient socket. No endodontic treatment was carried out either during or after the ATT. At six-month and 2-year clinical examination the patient was asymptomatic; the transplanted tooth was still functional, with no evidence of marginal periodontal pathosis. At the same follow ups, radiographic evaluation illustrated bone regeneration, normal PDL, and absence of external root resorption. Transplantation of mature third molar seems to be a promising method for replacing a lost permanent molar tooth and restoring aesthetics and function.

Asgary, Saeed

2009-01-01

352

Autogenous transplantation of mandibular third molar to replace tooth with vertical root fracture.  

PubMed

Autogenous tooth transplantation (ATT) can be considered when there is a hopeless molar tooth and suitable donor present. This report presents an unconventional case of successful ATT of a third molar replacing the adjacent fractured second molar in a 33 year old woman. This wisdom tooth had completely developed roots. Root-end filling with Calcium Enriched Mixture (CEM) cement was performed in the third molar. The second molar was extracted non-traumatically without any bone removal; the wisdom tooth was immediately transplanted into the recipient socket. No endodontic treatment was carried out either during or after the ATT. At six-month and 2-year clinical examination the patient was asymptomatic; the transplanted tooth was still functional, with no evidence of marginal periodontal pathosis. At the same follow ups, radiographic evaluation illustrated bone regeneration, normal PDL, and absence of external root resorption. Transplantation of mature third molar seems to be a promising method for replacing a lost permanent molar tooth and restoring aesthetics and function. PMID:24003333

Asgary, Saeed

2009-01-01

353

Prevalence of taurodontism in primary mandibular first molars of ethnic Indian children.  

PubMed

The objective of this study was to determine the prevalence of taurodontism in primary mandibular first molars in ethnic Indian children using periapical radiographs. Periapical radiographs of 274 children obtained from December 2008 to August 2010 were retrospectively screened and examined. Radiographs of 196 patients (99 boys and 97 girls; ages 2.5-10.5) with bilateral primary mandibular first molars were randomly selected and evaluated. The gender, symmetry, and frequencies of occurrence of taurodont primary mandibular first molars were compared and the obtained data were statistically analyzed using the x2 test. Eight (4.08%) taurodont primary mandibular first molars were found with a bilateral incidence of a symmetrical distribution of 38% (3/8). The prevalence of taurodontism in primary mandibular first molars did not differ significantly between right and left sides or with gender (P ? 0.05). The results of the present study indicate that approximately 4% of Indian children had taurodontism in primary mandibular first molars. Clinicians should be aware of the prevalence of this anatomic variant in primary mandibular first molars among the Indian population for early identification of taurodonts and for rendering the best care during dental treatment. PMID:23032243

Nagaveni, N B; Radhika, N B

2012-01-01

354

Piezoelectric bone surgery in the treatment of an osteoma associated with an impacted inferior third molar: a case report  

PubMed Central

Summary Operative removal of impacted mandibular third molars is a common and not riskless surgical procedure. We present an emblematic case of an osteoma closely associated with an impacted third left mandibular molar treated by Mectron Piezosurgery medical ultrasonic device.

D'Amato, Salvatore; Sgaramella, Nicola; Vanore, Laura; Piombino, Pasquale; Orabona, Giovanni Dell'Aversana; Santagata, Mario

2014-01-01

355

Placental mesenchymal dysplasia initially diagnosed as partial mole.  

PubMed

Placental mesenchymal dysplasia is a rare condition of pregnancy that presents as macroscopic features of molar change in the placenta and normal karyotype fetus. These cases are often misdiagnosed as partial mole. We report a new case of mesenchymal dysplasia. A 27-year-old Japanese primigravida delivered an 820 g female baby (46XX karyotype) without congenital anomalies at 27 weeks gestation due to massive bleeding with placenta previa. The placenta had mimicking partial moles, grape-like vesicles and normal villi that diffusely occupied the area on the maternal surface of the placenta. Pathologically, enlarged stem villi contained loose, moderately cellular connective tissue with focal cistern-like formation, and peripherally located vessels. Abnormal trophoblastic proliferation and trophoblastic inclusions were not observed in any of the sections examined. Some villi contained chorioangiomatoid changes. The mother and child were followed up for more than 5 years and showed no sign of trophoblastic disease or Beckwith-Wiedemann syndrome features. PMID:14629309

Matsui, Hideo; Iitsuka, Yoshinori; Yamazawa, Koji; Tanaka, Naotake; Mitsuhashi, Akira; Seki, Katsuyoshi; Sekiya, Souei

2003-11-01

356

Implementing partial least squares  

Microsoft Academic Search

Partial least squares (PLS) regression has been proposed as an alternative regression technique to more traditional approaches such as principal components regression and ridge regression. A number of algorithms have appeared in the literature which have been shown to be equivalent. Someone wishing to implement PLS regression in a programming language or within a statistical package must choose which algorithm

M. C. Denham

1995-01-01

357

Partial Dead Code Elimination  

Microsoft Academic Search

A new aggressive algorithm for the elimination of par- tially dead code is presented, i.e., of code which is only dead on some program paths. Besides being more pow- erful than the usual approaches to dead code elimina- tion, this algorithm is optimal in the following sense: partially dead code remaining in the resulting program cannot be eliminated without changing

Jens Knoop; Oliver Rüthing; Bernhard Steffen

1994-01-01

358

Generalized Partial Directed Coherence  

Microsoft Academic Search

This paper re-examines the definition of partial directed coherence (PDC) which was recently introduced as a linear frequency-domain quantifier of the multivariate relationship between simultaneously observed time series for application in functional connectivity inference in neuroscience. The present reappraisal aims at improving PDC's performance under scenarios that involve severely unbalanced predictive modelling errors (innovations noise). The present modification turns out

L. A. Baccald; F. de Medicina

2007-01-01

359

Partial disassembly of peroxisomes  

Microsoft Academic Search

ABSTRACT Rat liver peroxisomes,were,subjected,to a variety of procedures,intended,to partially disassemble,or damage,them; the effects were,analyzed,by recentrifugation into sucrose gradients, enzyme analyses, electron microscopy, and SDS PAGE. Freezing and thawing,or mild sonication released some,matrix proteins and produced,apparently intact peroxisomal,\\

Stefan E. H. Alexson; Yukio Fujiki; Helen Shio; Paul B. Lazarow

1985-01-01

360

Partial gravity habitat study  

NASA Technical Reports Server (NTRS)

The purpose of this study is to investigate comprehensive design requirements associated with designing habitats for humans in a partial gravity environment, then to apply them to a lunar base design. Other potential sites for application include planetary surfaces such as Mars, variable-gravity research facilities, and a rotating spacecraft. Design requirements for partial gravity environments include locomotion changes in less than normal earth gravity; facility design issues, such as interior configuration, module diameter, and geometry; and volumetric requirements based on the previous as well as psychological issues involved in prolonged isolation. For application to a lunar base, it is necessary to study the exterior architecture and configuration to insure optimum circulation patterns while providing dual egress; radiation protection issues are addressed to provide a safe and healthy environment for the crew; and finally, the overall site is studied to locate all associated facilities in context with the habitat. Mission planning is not the purpose of this study; therefore, a Lockheed scenario is used as an outline for the lunar base application, which is then modified to meet the project needs. The goal of this report is to formulate facts on human reactions to partial gravity environments, derive design requirements based on these facts, and apply the requirements to a partial gravity situation which, for this study, was a lunar base.

Capps, Stephen; Lorandos, Jason; Akhidime, Eval; Bunch, Michael; Lund, Denise; Moore, Nathan; Murakawa, Kiosuke

1989-01-01

361

Partial polarizer filter  

NASA Technical Reports Server (NTRS)

A birefringent filter module comprises, in seriatum. (1) an entrance polarizer, (2) a first birefringent crystal responsive to optical energy exiting the entrance polarizer, (3) a partial polarizer responsive to optical energy exiting the first polarizer, (4) a second birefringent crystal responsive to optical energy exiting the partial polarizer, and (5) an exit polarizer. The first and second birefringent crystals have fast axes disposed + or -45 deg from the high transmitivity direction of the partial polarizer. Preferably, the second crystal has a length 1/2 that of the first crystal and the high transmitivity direction of the partial polarizer is nine times as great as the low transmitivity direction. To provide tuning, the polarizations of the energy entering the first crystal and leaving the second crystal are varied by either rotating the entrance and exit polarizers, or by sandwiching the entrance and exit polarizers between pairs of half wave plates that are rotated relative to the polarizers. A plurality of the filter modules may be cascaded.

Title, A. M. (inventor)

1978-01-01

362

Morphology of partial globozoospermia.  

PubMed

Total globozoospermia is a rare sperm morphology disorder that consists of 100% round-headed, acrosomeless spermatozoa. There is also a larger group of patients whose sperm cells are partially acrosomeless. The aim of this investigation was to describe partial globozoospermia compared to total globozoospermia and normozoospermia. Ejaculates from 10 patients with more than 50% acrosomeless spermatozoa (partial globozoospermia), 3 patients with total globozoospermia, and 9 normozoospermic controls were analyzed with light microscopy, transmission electron microscopy, and flow cytometry. Qualitative and quantitative examination of spermatozoa from the 3 groups shows differences in the percentage of round-headed sperm cells and acrosome malformation. Total globozoospermia presents as a homogenous kind of teratozoospermia. Partial globozoospermia is a distinctive sperm malformation with an increased proportion of round-headed sperm cells and acrosome malformations compared to normozoospermia, which exists separately from total globozoospermia. It thereby contains oval sperm cells that may have distinctive malformations of the sperm head matrix, but also morphologically normal sperm cells that may be used in a clinical setting. PMID:20864651

Dam, Anika H; Ramos, Liliana; Dijkman, Henry B; Woestenenk, Rob; Robben, Hannie; van den Hoven, Leonie; Kremer, Jan A

2011-01-01

363

Two-Rooted Maxillary First Molars with Two Canals: A Case Series  

PubMed Central

Thorough understanding of the anatomic and internal morphology of a root canal system is absolutely essential for the success of endodontic treatment. Since permanent maxillary first molars have shown variation in internal anatomy, morphology, this tooth has been reviewed extensively. Presence of two canals in a two-rooted maxillary first molar has rarely been reported in studies describing tooth and root canal anatomies. In this report, three cases are presented, which involve the root canal treatment of maxillary first molars with fusion of the two buccal roots.

Shakouie, Sahar; Mokhtari, Hadi; Ghasemi, Negin; Gholizadeh, Seddigheh

2013-01-01

364

Ectopic eruption of maxillary first permanent molars in children with cleft lip.  

PubMed

The purpose of this study was to determine the incidence of ectopic eruption of the maxillary first permanent molars in cleft patients. Panoramic radiographs of 70 Brazilian Caucasian children, 6 to 8 years old and with complete unilateral cleft lip and alveolus, were assessed. Fourteen of 70 patients (20%) presented with ectopic eruption of one or both maxillary first permanent molars. Sixteen of 19 ectopically erupted molars (85%) were of a reversible type of ectopic eruption and 3 (15%) were irreversible. No significant differences were found between sexes or between cleft sides. PMID:8893107

da Silva Filho, O G; De Albuquerque, M V; Kurol, J

1996-01-01

365

Vital Pulp Therapy with Three Different Pulpotomy Agents in Immature Molars: A Case Report  

PubMed Central

Introduction This case report describes apexogenesis treatment of three molar teeth of an 8-year-old boy using three different pulpotomy agents. Methods Pulpotomy was performed on decayed immature molar teeth with established irreversible pulpitis and the remaining pulp was capped with either zinc oxide eugenol, ProRoot mineral trioxide aggregate or calcium-enriched mixture (CEM) cement. Teeth were restored with stainless steel crowns. Results Eighteen months clinical and radiographic follow-up revealed successful preservation of pulpal vitality with continued root development in all treated teeth. Conclusion Based on this case report, CEM cement may be an alternative option for pulpotomy treatment of immature permanent molars.

Harandi, Azadeh; Forghani, Maryam; Ghoddusi, Jamileh

2013-01-01

366

Extraction of upper first molar resulting in fracture of maxillary tuberosity.  

PubMed

Fracture of the maxillary tuberosity sometimes can happen when pneumatization of the maxillary sinus extends between the roots of upper molars. Some factors may lead to this complication including prominent or curved roots, chronic periapical infection, hypercementosis, root ankylosis and tooth fusion. This paper reports a case with fracture of the maxillary tuberosity following extraction of an upper first molar in general dental practice. Prevention from any complication during extractions of maxillary molars with large antral enlargement is possible with careful preoperative examination and accurate surgical planning. The general dentist should be prepared to refer such cases to an oral surgeon when facing difficulties like the presented case. PMID:19208000

Altu?, Hasan Ayberk; Sahin, Sermet; Sencimen, Metin; Dogan, Necdet

2009-02-01

367

Removal of a Maxillary Third Molar Displaced into Pterygopalatine Fossa via Intraoral Approach.  

PubMed

The removal of impacted maxillary third molars is one of the most common procedures performed in oral and maxillofacial surgery units with low rates of complications and morbidity. A few cases of accidental displacement of third molars into adjacent anatomical spaces, such as the infratemporal fossa, the pterygomandibular space, the maxillary sinus, buccal space, or the lateral pharyngeal space, during surgical interventions have been reported. In this paper, a case of a maxillary third molar accidentally displaced into the pterygopalatine fossa is presented, and the removal of the tooth via intraoral approach is described. PMID:23476814

Ozer, Nedim; Uçem, Fulya; Saruhano?lu, Alp; Yilmaz, Serdar; Tanyeri, Hakk?

2013-01-01

368

Removal of a Maxillary Third Molar Displaced into Pterygopalatine Fossa via Intraoral Approach  

PubMed Central

The removal of impacted maxillary third molars is one of the most common procedures performed in oral and maxillofacial surgery units with low rates of complications and morbidity. A few cases of accidental displacement of third molars into adjacent anatomical spaces, such as the infratemporal fossa, the pterygomandibular space, the maxillary sinus, buccal space, or the lateral pharyngeal space, during surgical interventions have been reported. In this paper, a case of a maxillary third molar accidentally displaced into the pterygopalatine fossa is presented, and the removal of the tooth via intraoral approach is described.

Ozer, Nedim; Ucem, Fulya; Saruhanoglu, Alp; Yilmaz, Serdar; Tanyeri, Hakk?

2013-01-01

369

The Determination of Partial Moments  

Microsoft Academic Search

In statistical decision theory, computations often involve the partial moments of a random variable. Several methods for determining partial moments are discussed, including direct calculation, the use of general formulas which apply to entire families of distributions, and the use of partial moment generating functions. Using these methods, formulas (some involving recursive relationships) are developed for the partial moments of

Robert L. Winkler; Gary M. Roodman; Robert R. Britney

1972-01-01

370

Radiographic evaluation of third molar genesis in Greek orthodontic patients  

PubMed Central

Objectives The study reported here investigated the first radiographic evidence of third molar (M3) formation, their incidence and distribution as well as their congenital absence on the right or the left side in either the maxilla or the mandible, in both male and female Greek orthodontic patients. Materials and methods A total of 618 panoramic radiographs were initially examined. After the application of inclusion/exclusion criteria, the group finally selected consisted of 428 patients (mean age 11.64 years, range 5–18): 179 males (mean age 11.73 ± 2.46) and 249 females (mean age 11.57 ± 2.45). The collected data were analyzed using SPSS software (IBM, Armonk, New York, NY, USA). The level of significance for all analyses was set to p = 0.05. The chi-square (?2) test was used to assess the relationships between variables. The Wilcoxon’s signed-rank test and the Mann-Whitney U test were also used for comparisons as well as the Spearman’s rho test for correlations. Results M3s were first detected in females at the age of 7 years whereas males followed one year later at the age of 8 years. A strong correlation between age and M3 development was revealed for both sexes (Spearman’s rho = 0.177, p = 0.05). Presence of all four M3s was the most common incidence (present in 70.8% of study subjects), followed by the agenesis of two (12.1%), agenesis of all four (8.4%), one (6.8%), and three (1.9%) M3s. Congenitally missing M3s in all subjects showed a significantly greater predilection for the maxilla over the mandible (19.6% and 15.5%, respectively) (Wilcoxon signed-rank test Z = ?2.404, p = 0.016). However, the distribution was found equal between the two sides of the jaws. The difference between the absent frequencies of M3s in the mandible and the maxilla was found statistically significant for the total sample (McNemar’s test, p < 0.001) and for males (p = 0.041) as well. Conclusion The study data may provide a reference for the M3 genesis in Greeks.

Barka, Georgia; Marathiotis, Konstantinos; Protogerakis, Michael; Zafeiriadis, Andreas

2013-01-01

371

[Dosimetric comparison of external partial breast irradiation with whole breast irradiation and partial breast brachytherapy].  

PubMed

Different techniques exist for the delivery of radiotherapy after breast conserving surgery. The conventional method is whole breast irradiation. However, in selected patients partial breast irradiation can be performed, either with external beams or brachytherapy. In the current study three irradiation techniques are compared regarding dosimetric aspects. Treatment plans of thirty women treated with external beam conformal partial breast irradiation (CONF) were evaluated using dose-volume histograms. For the same patients whole breast irradiation plans (WBI) were made and compared with the CONF ones. Breast and lung of both sides, and heart at left sided lesions were contoured as organs at risk. After this, dose plans of another thirty patients treated with interstitial brachytherapy (IBT) were analyzed and compared with the CONF plans. According to our results the 90% isodose curve covered at least 97% of the target volume at all three techniques, and this value was 100% for CONF. The maximal dose within target volume was 106% in CONF and 115% in WBI plans. Volume of ipsilateral breast receiving the prescribed dose was 66%, 15% and 13% in the WBI, CONF and IBT plans, respectively. The dose to the contralateral breast was less for CONF compared to WBI. Volume of the ipsilateral lung receiving 30% of the prescribed dose was 15%, 8% and 1%, the maximal dose was 105%, 94% and 47% in the WBI, CONF and IBT plans, respectively. In the same order the maximal dose to the heart was 82%, 49% and 25%, while the dose irradiated to 5% of the heart volume was 27%, 19% and 14% at left sided lesions. Regarding target coverage, the conformal technique was the best, and the dose was more homogeneous than at WBI. With respect to dose to organs at risk the partial breast irradiation techniques were much more favorable than WBI, and the lowest doses occurred in the IBT treatment plans. PMID:25010759

Bodács, István; Polgár, Csaba; Major, Tibor

2014-07-01

372

Natural enamel caries: a comparative histological study on biochemical volumes.  

PubMed

This study aimed to test the hypothesis that organic volume is the main variable for explaining the optical properties and predictive degree of diffusion of enamel histological points at zones of natural enamel caries (NEC; surface layer, SL, n = 30, and body of the lesion, BL, n = 58) and normal enamel (NE, n = 131). Molars with either NEC or NE were quantitatively analyzed regarding the mineral, organic and water volumes (considered as effective pore volume), opacity (predicted in 94% of cases by water volume in NEC), and water volume more easily available for diffusion, ?d (squared water volume divided by the nonmineral volume; related to permeability). NEC presented lower mineral volumes and higher organic volumes, effective pore volume and opacity than NE. External origin of organic volume in NEC was evidenced by an organic gradient decreasing from the surface inward (R2 = -0.7), which was not detected in teeth with NE only; ?d values of the SL and NE were similar and both were lower (p < 0.0001) than that of the BL. Comparing the SL from both NEC and artificial enamel caries (AEC; published data; n = 71), with similar mineral volumes, against developing enamel (published data), AEC showed more effective pore volume (3 times higher), higher ?d and opacity than NEC mainly due to differences in organic volumes. Our results reasonably matched widely known features of NEC histological zones, and confirmed the organic volume as the main variable for explaining optical properties and ?d (related to permeability). PMID:23222001

Barbosa de Sousa, F; Dias Soares, J; Sampaio Vianna, S

2013-01-01

373

Accessory roots in maxillary molar teeth: a review and endodontic considerations.  

PubMed

Maxillary molar teeth may have accessory roots. The aim of this paper is to review and discuss the endodontic implications of this anatomical variation. A review of the literature was undertaken to identify studies and reported cases where accessory roots have been recorded in maxillary molar teeth. The results show that although the prevalence of accessory roots in maxillary molar teeth is low, they can exist in all three types of maxillary molar teeth, and they may be located palatally, buccally, mesially or distally. Hence, it is essential that dentists undertaking root canal treatment thoroughly assess all teeth to determine how many roots are present in order to provide the best possible outcome of treatment for the patient. PMID:22624750

Ahmed, H M A; Abbott, P V

2012-06-01

374

Root Canal Morphology of Mandibular First Permanent Molars in an Indian Population  

PubMed Central

An in vitro study was performed to determine the number of roots, root canals per tooth, root canal configurations, and frequency of isthmi and apical deltas in mandibular first permanent molars in an Indian population. Hundred and fifty mandibular first permanent molars were collected and subjected to clearing technique. The cleared teeth were examined in a stereomicroscope under 7.5x magnifications. The canal configurations were categorized using Vertucci's classification. Overall 94.6% of the mandibular first molars had two roots, and 5.3% had extradistal roots (distolingual root). In addition, 64% of the specimens had three root canals, and 36% had four root canals. The most common canal configurations of mesial and distal roots were Vertucci type IV (54%) and type I (65.3%), respectively. Clinician should be aware of the complex root canal morphology of mandibular first molars among the Indian population before and during the root canal treatment.

Chourasia, Hemant Ramesh; Meshram, Ganesh K.; Warhadpande, Manjusha; Dakshindas, Darshan

2012-01-01

375

How Many Digits Should We Use in Formula or Molar Mass Calculations?  

ERIC Educational Resources Information Center

The calculations of uncertainties in the formula or molar masses of compounds are streamlined. Three rules of increasing complexity are proposed, which overestimate the uncertainty so there is little if any risk that the true values are missed.

Svensson, Christer

2004-01-01

376

Effects of ozone therapy on pain, swelling, and trismus following third molar surgery.  

PubMed

The aim of this study was to evaluate the efficacy of therapeutic ozone application in the management of pain, swelling, and trismus associated with the surgical removal of impacted mandibular third molars. Sixty consecutive patients with asymptomatic bilateral impacted mandibular third molars were recruited into the study. Randomly, by use of envelops, the molar on one side was extracted and ozone therapy was given (study side); the molar on the other side was extracted 2 weeks later and sham ozone therapy was given (negative control side). The mean age of the 60 patients was 22.6±2.3 years (range 18-25 years). No differences were found between the two sides for mouth opening or swelling. The degree of pain and the number of analgesic tablets taken was significantly lower for the study side. This study showed ozone therapy to have a positive effect on OHIP-14 questionnaire results. PMID:24332588

Kazancioglu, H O; Kurklu, E; Ezirganli, S

2014-05-01

377

Simplifying Chemical Reactor Design by using Molar Quantities Instead of Fractional Conversion.  

ERIC Educational Resources Information Center

Explains the advantages of using molar quantities in chemical reactor design. Advocates the use of differential versions of reactor mass balances rather than the integrated forms. Provides specific examples and cases to illustrate the principles. (ML)

Brown, Lee F.; Falconer, John L.

1987-01-01

378

Alkaline phosphatase activity in sequential mouse molar tooth development an electron microscopic study  

Microsoft Academic Search

First molar teeth of developing Swiss albino mice were studied for alkaline phosphatase activity. Specimens ranging from 19 days in utero to 8 days postnatal were used (prebell through appositional and mineralization stages).

Edward P. Leonard; D. Vincent Provenza

1973-01-01

379

Root Canal Morphology of Human Mandibular First Permanent Molars in an Iranian Population  

PubMed Central

Background and aims The knowledge of variations in root canal morphology is critical for a successful endodontic treatment. The purpose of this study was to investigate variations in the root canal system of human mandibular first permanent molars in an Iranian population. Materials and methods In this study, 209 mandibular first molar teeth were decalcified, dye-injected, and cleared in order to determine the number and configuration of the root canals. Results The results demonstrated that 65.56% of the mandibular first molars under study had three, 31.57% had four and 2.87% had two canals. Conclusion According to the results of this study and considering variations in the root canal systems of the mandibular first molars, it seems that great care should be taken in the root canal treatment of these teeth.

Shahi, Shahriar; Yavari, Hamid Reza; Rahimi, Saeed; Torkamani, Reza

2008-01-01

380

Root Canal Configuration of Maxillary First Permanent Molars in an Iranian Population  

PubMed Central

Background and aims It is critical to have a proper knowledge of the normal anatomy of the pulp and its variations for the success of endodontic treatment. The purpose of this study was to investigate variations in the root canal system of maxillary first permanent molars in an Iranian population. Materials and methods In this study, 137 maxillary first molars were decalcified, dye-injected, cleared and studied. Results The results demonstrated that 37.96% of the maxillary first molars under study had three canals, 58.4% had four canals and 3.64% had five canals. Conclusion According to the results of this study and considering variations in the root canal systems of maxillary first molars, it seems that great care should be taken in the root canal treatment of these teeth.

Shahi, Shahriar; Yavari, Hamid Reza; Rahimi, Saeed; Ahmadi, Ali

2007-01-01

381

A Bibliography of Recreational Mathematics, Volume 3.  

ERIC Educational Resources Information Center

This book is a partially annotated bibliography of books, articles and periodicals concerned with mathematical games, puzzles, tricks, amusements, and paradoxes. Because the literature in recreational mathematics has proliferated to amazing proportions since Volume 2 of this series (ED 040 874), Volume 3 is more than just an updating of the…

Schaaf, William L.

382

Nonlinear partial least squares  

Microsoft Academic Search

We propose a new nonparametric regression method for high-dimensional data, nonlinear partial least squares (NLPLS), which is motivated by projection-based regression methods, e.g. PLS, projection pursuit regression and feedforward neural networks. The model takes the form of a composition of two functions. The first function in the composition projects the predictor variables onto a lower-dimensional curve or surface yielding scores,

E. C. Malthouse; A. C. Tamhane; R. S. H. Mah

1997-01-01

383

Partial Alphabetic Trees  

Microsoft Academic Search

In the partial alphabetic tree problem we are given a multiset of nonnegative weights W = w\\u000a 1, . . . , w\\u000a \\u000a n\\u000a , partitioned into k ? n blocks B\\u000a 1, . . . , B\\u000a k. We want to find a binary tree T where the elements of W resides in its leaves such that if we

Arye Barkan; Haim Kaplan

2002-01-01

384

Linear Partial Differential Equations  

NSDL National Science Digital Library

This course, presented by MIT and taught by professor Matthew Hancock, covers the partial differential equations of applied mathematics, including diffusion, Laplace/Poisson, and wave equations. Methods and tools for solving these equations are also taught. The course includes lecture notes as well as assignments and exams with solutions. MIT presents OpenCourseWare as free educational material online. No registration or enrollment is required to use the materials.

Hancock, Matthew

2011-01-11

385

Representing partial ignorance  

Microsoft Academic Search

This paper advocates the use of nonpurely probabilistic approaches to higher-order uncertainty. One of the major arguments of Bayesian probability proponents is that representing uncertainty is always decision-driven and as a consequence, uncertainty should be represented by probability. Here we argue that representing partial ignorance is not always decision-driven. Other reasoning tasks such as belief revision for instance are more

Didier Dubois; Henri Prade; Philippe Smets

1996-01-01

386

Static Partial Order Reduction  

Microsoft Academic Search

The state space explosion problem is central to automatic verification algorithms. One of the successful techniques to abate\\u000a this problem is called ‘partial order reduction’. It is based on the observation that in many cases the specification of concurrent\\u000a programs does not depend on the order in which concurrently executed events are interleaved. In this paper we present a new

Robert P. Kurshan; Vladimir Levin; Marius Minea; Doron Peled; Hüsnü Yenigün

1998-01-01

387

Class, type and position of 9148 surgically removed third molars in 3206 patients: A retrospective study  

PubMed Central

Objective: To investigate the class, type, position, diagnosis and most common procedures used in the surgical removal of third molars, and evaluate the sex and age distribution in a representative sample of Mexican patients. Study Design: A retrospective descriptive study was made covering the period 1993-2008 in relation to 9148 extracted third molars in 3206 patients treated in the Dental School of Salle Bajío University, A.C. (Mexico). Patients of either sex and aged 11-59 years, with at least one third molar programmed for surgical removal, were included in the study. A descriptive statistical study was made. Results: The mean patient age was 27.6 ± 10.6 years. There were 2093 females (65.3%) and 1111 males (34.6%). In relation to the 4025 upper molars, extraction was decided for prophylactic reasons in 3827 cases (95.08%). Type A presentations were recorded in 1929 cases (47.9%), with a vertical position in 1931 teeth (48%). In relation to the 5123 lower third molars, extraction was likewise most often indicated for prophylactic reasons (4424 cases, 86.36%). A total of 2353 teeth corresponded to type A (45.9%), 2545 were class I cases (49.7%), and a mesioangular position was observed in 1850 cases (36.1%). Conclusions: The present study shows that in Mexican patients, upper third molars most often correspond to type A and class I, with a vertical position, while lower third molars predominantly correspond to type A and class I, with a mesioangular position. This information can help dental surgeons take better decisions before and after surgery, to the benefit of their patients. Key words:Third molars, retrospective review, surgical removal.

Rocha-Navarro, Miriam L.; Acosta-Veloz, Anselmo L.; Juarez-Hernandez, Angelica

2012-01-01

388

Maxillary tuberosity fracture and subconjunctival hemorrhage following extraction of maxillary third molar  

PubMed Central

Extraction of teeth is the most common minor surgical procedure performed. Complication of extraction ranges from periodontal injury to fracture of jaw in the mandible and fracture of tuberosity and oroantral communication in the maxilla. Subconjunctival hemorrhage after extraction of maxillary molar is a very rare complication, and so far, only one case is reported in the literature. We report a case of subconjunctival hemorrhage with maxillary tuberosity fracture after maxillary third molar extraction.

Thirumurugan, Kanagasabapathy; Munzanoor, Rathinam Ramesh Babu; Prasad, Gnanasekaran Arun; Sankar, Kannan

2013-01-01

389

Investigation on the utility of permanent maxillary molar cusp areas for sex estimation  

Microsoft Academic Search

Digital photogrammetric methods were employed to assess the level of sexual dimorphism present in permanent maxillary molar\\u000a cusp areas of black South Africans (130 males, 105 females). Odontometric standards were then developed for diagnosing sex,\\u000a based on the cusp area data derived for these teeth. Results demonstrated that all cusp area measurements of both the first\\u000a and second maxillary molars

P. James Macaluso Jr

2011-01-01

390

Thermochemical studies for determination of the molar enthalpy of formation of aniline derivatives  

Microsoft Academic Search

The standard (po=0.1 MPa) molar enthalpies of combustion atT=298.15 K were measured by static bomb combustion calorimetry for liquidN,N-diethylaniline,N,N-dimethyl-m-toluidine,N,N-dimethyl-p-toluidine, andN-ethyl-m-toluidine. Vaporization enthalpies forN,N-dimethyl-m-toluidine andN-ethyl-m-toluidine were determined by correlation gas chromatography. Derived standard molar values of ?fH

Manuel A. V. Ribeiro da Silva; Maria Dores M. C. Ribeiro da Silva; Maria Fatima B. M. Monteiro; Maria Luísa A. C. N. Gomes; James S. Chickos; Anjanette P. Smith; Joel F. Liebman

1996-01-01

391

Molar conductivity calculation of Li-ion battery electrolyte based on mode coupling theory.  

PubMed

A method is proposed to calculate molar conductivity based on mode coupling theory in which the ion transference number is introduced into the theory. The molar conductivities of LiPF6, LiClO4, LiBF4, LiAsF6 in PC (propylene carbonate) are calculated based on this method. The results fit well to the literature data. This presents a potential way to calculate the conductivities of Li-ion battery electrolytes. PMID:16392907

Pu, Weihua; He, Xiangming; Lu, Jiufang; Jiang, Changyin; Wan, Chunrong

2005-12-15

392

IRON (III) MOLAR EXTINCTION COEFFICIENTS IN LIGHT AND HEAVY WATER SOLUTIONS  

Microsoft Academic Search

The iron(III) molar extinction coefficient in HâO-0.4 M HâSO\\/; sub 4\\/ solution at maximum absorption and 25 deg C, epsilon \\/sub s\\/, was ; determined to be 2220 plus or minus 20 liters mole⁻¹ cm⁻¹. The ; ratio of the iron(III) molar extinction coefficient in DâO-0.4 M HâSO\\/; sub 4\\/ solution at maximum absorption and 25 deg C to epsilon

J. W. Boyle; H. A. Mahlman

1962-01-01

393

A method for the determination of the molar extinction coefficient of structure-linked chromophores  

Microsoft Academic Search

Synopsis  This paper describes a general method for the determination of the molar extinction ceefficient of a chromophore covalently bound to structure-linked groups, without isolating the compound formed. The method is illustrated by the determination of the molar extinction coefficient of the reaction product of 2,4-dinitro-1-fluorobenzene (DNFB) with films of aminoethyl-cellulose (AE-cellulose). The method is based on the relation between the

J. P. R. Van Dalen; W. B. A. M. Ahsmann; P. Van Duijn

1970-01-01

394

Maxillary tuberosity fracture and subconjunctival hemorrhage following extraction of maxillary third molar.  

PubMed

Extraction of teeth is the most common minor surgical procedure performed. Complication of extraction ranges from periodontal injury to fracture of jaw in the mandible and fracture of tuberosity and oroantral communication in the maxilla. Subconjunctival hemorrhage after extraction of maxillary molar is a very rare complication, and so far, only one case is reported in the literature. We report a case of subconjunctival hemorrhage with maxillary tuberosity fracture after maxillary third molar extraction. PMID:23633874

Thirumurugan, Kanagasabapathy; Munzanoor, Rathinam Ramesh Babu; Prasad, Gnanasekaran Arun; Sankar, Kannan

2013-01-01

395

Effects of parathyroid hormone on odontogenesis of the mouse embryonic molar tooth In vitro  

Microsoft Academic Search

Summary  Mandibular first molars of 17-day-old mouse embryos were culturedin vitro to examine the histological effects of various concentrations of parathyroid hormone (PTH) on odontogenesis of the molars.\\u000a PTH did not affect the cytodifferentiation of mesenchymal cells into preodontoblasts but inhibited that of preodontoblasts\\u000a into odontoblasts. Consequently, the odontoblasts failed to undergo dentinogenesis. On the other hand, inner enamel epithelium\\u000a achieved

Y. Sakakura

1987-01-01

396

Improving the developability profile of pyrrolidine progesterone receptor partial agonists  

SciTech Connect

The previously reported pyrrolidine class of progesterone receptor partial agonists demonstrated excellent potency but suffered from serious liabilities including hERG blockade and high volume of distribution in the rat. The basic pyrrolidine amine was intentionally converted to a sulfonamide, carbamate, or amide to address these liabilities. The evaluation of the degree of partial agonism for these non-basic pyrrolidine derivatives and demonstration of their efficacy in an in vivo model of endometriosis is disclosed herein.

Kallander, Lara S.; Washburn, David G.; Hoang, Tram H.; Frazee, James S.; Stoy, Patrick; Johnson, Latisha; Lu, Qing; Hammond, Marlys; Barton, Linda S.; Patterson, Jaclyn R.; Azzarano, Leonard M.; Nagilla, Rakesh; Madauss, Kevin P.; Williams, Shawn P.; Stewart, Eugene L.; Duraiswami, Chaya; Grygielko, Eugene T.; Xu, Xiaoping; Laping, Nicholas J.; Bray, Jeffrey D.; Thompson, Scott K. (GSKPA)

2010-09-17

397

The influence of surface state and saturation state on the dissolution kinetics of biogenic aragonite in seawater  

USGS Publications Warehouse

Uses several realistic partial molar volume changes (??V) for aragonite dissolution in seawater. Indicates that the molar volume change for aragonite dissolution is within the bounds -37 cm 3/mole ?????V ??? -39.5 cm3/mole. -from Authors

Acker, J. G.; Byrne, R. H.

1989-01-01

398

Partial volume effect as a hidden covariate in DTI analyses  

Microsoft Academic Search

During the last decade, diffusion tensor imaging (DTI) has been used extensively to investigate microstructural properties of white matter fiber pathways. In many of these DTI-based studies, fiber tractography has been used to infer relationships between bundle-specific mean DTI metrics and measures-of-interest (e.g., when studying diffusion changes related to age, cognitive performance, etc.) or to assess potential differences between populations

Sjoerd B. Vos; Derek K. Jones; Max A. Viergever; Alexander Leemans

2011-01-01

399

Magnetic Resonance Image Tissue Classification Using a Partial Volume Model  

Microsoft Academic Search

We describe a sequence of low-level operations to isolate and classify brain tissue within T1-weighted magnetic resonance images (MRI). Our method first removes nonbrain tissue using a combination of anisotropic diffusion filtering, edge detection, and mathematical morphology. We compensate for image nonuniformities due to magnetic field inhomogeneities by fitting a tricubic B-spline gain field to local estimates of the image

David W. Shattuck; Stephanie R. Sandor-Leahy; Kirt A. Schaper; David A. Rottenberg; Richard M. Leahy

2001-01-01

400

Mandibular first and second molar. The variability of roots and root canal system.  

PubMed

The root and canal anatomy of mandibular first and second molars has normally recurring features, as well as a great number of atypias. Normally mandibular first and second molars have two roots, one is mesial and the other is distal, and at least three main canals. The roots of the second molar can change from one to three, the first molar can have also four roots; the canals can change from three to even six. The conventional root canal anatomy indicates the location of the initial access. The knowledge of both the normal and abnormal anatomy of molars shows the parameters under which root canal therapy is to be executed and can directly modify the probability of success. This is the reason why endodontists must be familiar with all abnormalities as well as their percentage. We present a review of the modern literature about the event of aberrances with references to the number and morphology in mandibular first and second molar root and root canals. PMID:9835748

Maggiore, C; Gallottini, L; Resi, J P

1998-09-01

401

Sharp mandibular bone irregularities after lower third molar extraction: Incidence, clinical features and risk factors  

PubMed Central

Objectives: The purpose of this study was to determine the incidence and clinical symptoms associated with sharp mandibular bone irregularities (SMBI) after lower third molar extraction and to identify possible risk factors for this complication. Study Design: A mixed study design was used. A retrospective cohort study of 1432 lower third molar extractions was done to determine the incidence of SMBI and a retrospective case-control study was done to determine potential demographic and etiologic factors by comparing those patients with postoperative SMBI with controls. Results: Twelve SMBI were found (0.84%). Age was the most important risk factor for this complication. The operated side and the presence of an associated radiolucent image were also significantly related to the development of mandibular bone irregularities. The depth of impaction of the tooth might also be an important factor since erupted or nearly erupted third molars were more frequent in the SMBI group. Conclusions: SMBI are a rare postoperative complication after lower third molar removal. Older patients having left side lower third molars removed are more likely to develop this problem. The treatment should be the removal of the irregularity when the patient is symptomatic. Key words:Third molar, postoperative complication, bone irregularities, age.

Alves-Pereira, Daniela; Valmaseda-Castellon, Eduard; Laskin, Daniel M.; Berini-Aytes, Leonardo; Gay-Escoda, Cosme

2013-01-01

402

Connection of Partial Order Logics and Partial Order Reduction Methods.  

National Technical Information Service (NTIS)

The authors examine the connection between 'equivalence robust' subsets of propositional temporal logics (LTL and CTL(star)), for which partial order reduction methods can be applied in model checking, and partial order logics and equivalences. For the li...

P. Niebert W. Penczek

1995-01-01

403

Excess volumes of binary mixtures that contain olive oil with alkyl and vinyl acetates  

Microsoft Academic Search

This paper reports densities and excess molar volumes for ethyl acetate, vinyl acetate, propyl acetate, isopropyl acetate,\\u000a and butyl acetate with olive oil at temperatures from 283.15–298.15 K. Redlich-Kister polynomials were fitted to the results\\u000a of excess volumes. All the systems showed slight deviations from ideality. The excess volumes decreased with the number of\\u000a carbon atoms of the acetate, but

Cristina González; Jos M. Resa; Juan Lanz

2000-01-01

404

Applications of partially quenched chiral perturbation theory  

SciTech Connect

Partially quenched theories are theories in which the valence- and sea-quark masses are different. In this paper we calculate the nonanalytic one-loop corrections of some physical quantities: the chiral condensate, weak decay constants, Goldstone boson masses, B{sub K}, and the K{sup +}{r_arrow}{pi}{sup +}{pi}{sup 0} decay amplitude, using partially quenched chiral perturbation theory. Our results for weak decay constants and masses agree with, and generalize, results of previous work by Sharpe. We compare B{sub K} and the K{sup +} decay amplitude with their real-world values in some examples. For the latter quantity, two other systematic effects that plague lattice computations, namely, finite-volume effects and unphysical values of the quark masses and pion external momenta, are also considered. We find that typical one-loop corrections can be substantial. {copyright} {ital 1998} {ital The American Physical Society}

Golterman, M.F.; Leung, K.C. [Department of Physics, Washington University, St. Louis, Missouri63130 (United States)] [Department of Physics, Washington University, St. Louis, Missouri63130 (United States)

1998-05-01

405

Esthetic removable partial dentures.  

PubMed

This article provides information regarding the many ways that removable partial dentures (RPDs) may be used to solve restorative problems in the esthetic zone without displaying metal components or conspicuous acrylic resin flanges. The esthetic zone is defined and described, as are methods for recording it. Six dental categories are presented that assist the dentist in choosing a variety of RPD design concepts that may be used to avoid metal display while still satisfying basic principles of RPDs. New materials that may be utilized for optimal esthetics are presented and techniques for contouring acrylic resin bases and tinting denture bases are described. PMID:15544224

Ancowitz, Stephen

2004-01-01

406

Furnace brazing under partial vacuum  

NASA Technical Reports Server (NTRS)

Brazing furnace utilizing partial-vacuum technique reduces tooling requirements and produces better bond. Benefit in that partial vacuum helps to dissociate metal oxides that inhibit metal flow and eliminates heavy tooling required to hold parts together during brazing.

Mckown, R. D.

1979-01-01

407

Partial preservation of frequencies in KAM theory  

NASA Astrophysics Data System (ADS)

We consider perturbations of moderately degenerate integrable or partially integrable Hamiltonian systems, so that unperturbed invariant n-tori with prescribed frequencies or frequency ratios do not persist, but there is preservation of, say, the first d < n frequencies or their ratios. Lagrangian and lower dimensional tori are treated in a unified way. The proofs are very simple and follow Herman's idea of 1990: we introduce external parameters to remove degeneracies and then eliminate these parameters making use of a suitable number-theoretical lemma concerning Diophantine approximations of dependent quantities. Parallel results for reversible, volume preserving and dissipative systems are also presented.

Sevryuk, Mikhail B.

2006-05-01

408

Is Titan Partially Differentiated?  

NASA Astrophysics Data System (ADS)

The recent measurement of the gravity coefficients from the Radio Doppler data of the Cassini spacecraft has improved our knowledge of the interior structure of Titan (Rappaport et al. 2008 AGU, P21A-1343). The measured gravity field of Titan is dominated by near hydrostatic quadrupole components. We have used the measured gravitational coefficients, thermal models and the hydrostatic equilibrium theory to derive Titan's interior structure. The axial moment of inertia gives us an indication of the degree of the interior differentiation. The inferred axial moment of inertia, calculated using the quadrupole gravitational coefficients and the Radau-Darwin approximation, indicates that Titan is partially differentiated. If Titan is partially differentiated then the interior must avoid melting of the ice during its evolution. This suggests a relatively late formation of Titan to avoid the presence of short-lived radioisotopes (Al-26). This also suggests the onset of convection after accretion to efficiently remove the heat from the interior. The outer layer is likely composed mainly of water in solid phase. Thermal modeling indicates that water could be present also in liquid phase forming a subsurface ocean between an outer ice I shell and a high pressure ice layer. Acknowledgments: This work was conducted at the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration.

Mitri, G.; Pappalardo, R. T.; Stevenson, D. J.

2009-12-01

409

Partially Ordered Models  

NASA Astrophysics Data System (ADS)

We provide a formal definition and study the basic properties of partially ordered random fields (PORF). These systems were proposed to model textures in image processing and to represent independence relations between random variables in statistics (in the latter case they are known as Bayesian networks). Our random fields are a generalization of probabilistic cellular automata (PCA) and their theory has features intermediate between that of discrete-time processes and the theory of statistical mechanical lattice fields. Its proper definition is based on the notion of partially ordered specification (POS), in close analogy to the theory of Gibbs measures. This paper contains two types of results. First, we present the basic elements of the general theory of PORFs: basic geometrical issues, definition in terms of conditional probability kernels, extremal decomposition, extremality and triviality, reconstruction starting from single-site kernels, relations between POM and Gibbs fields. Second, we prove three uniqueness criteria that correspond to the criteria known as uniform boundedness, Dobrushin uniqueness and disagreement percolation in the theory of Gibbs measures.

Deveaux, Vincent; Fernández, Roberto

2010-11-01

410

Benign partial epilepsies in infancy  

Microsoft Academic Search

Benign partial epilepsies are not rare in infancy and comprise two forms, although both are closely related. One is partial epilepsy with complex partial seizures (CPS) and the other one with secondarily generalized seizures (SGS). The most frequent site of seizure origin was in the temporal area in the former and central, parietal or occipital area in the latter. The

Kazuyoshi Watanabe; Akihisa Okumura

2000-01-01

411

Accuracy of scanography using storage phosphor plate systems and film for assessment of mandibular third molars  

PubMed Central

Objectives The aim of this study was to compare the diagnostic accuracy of two digital photostimulable storage phosphor (PSP) systems and film for assessment of mandibular third molars before surgery. Methods 110 patients were referred to have both their mandibular third molars removed. Each patient underwent a radiographic examination with scanography using either Digora (Soredex, Helsinki, Finland) and film or VistaScan (Dürr Dental, Beitigheim-Bissingen, Germany) and film in a randomized paired design. Two observers examined the following variables on the scanograms: bone coverage, angulation of the tooth in the bone, number of roots, root morphology and the relationship to the mandibular canal. In 75 of the pairs (Digora/film pair = 38 and Vista/film pair = 37) both third molars were eventually removed. During and after surgery the same variables were assessed, which served as reference standard for the radiographic assessments. The Wilcoxon signed-rank test tested differences in accuracy (radiographic compared with surgical findings) between Digora/film and between Vista/film. Results There was no statistically significant difference between the diagnostic accuracy of film and either of the two digital receptors for assessment of mandibular third molars before surgery (P > 0.05), although Digora obtained a higher accuracy than film. Conclusions Scanography is a valuable method for examination of mandibular third molars before removal and the PSP digital receptors in this study were equal to film for this purpose.

Matzen, LH; Christensen, J; Wenzel, A

2011-01-01

412

Anatomical Relationship of Lingual Nerve to the Region of Mandibular Third Molar  

PubMed Central

ABSTRACT Objectives This study evaluated the relationship of the lingual nerve with the adjacent anatomical structures of the mandibular third molar region, influencing the dentist to be aware of the variability of these relationships. Material and Methods Samples of 24 human corpse half-heads were selected and divided according with the presence or absence of the mandibular third molars. The lingual nerve (LN) was explored, showing its run from the oblique line until its crossing with the submandibular gland duct. The measurements along the LN and the adjacent anatomical structures were taken at the retromolar, molar and sublingual region with the use of a digital caliper. Results The distance from the LN and the third molar socket, which represents the horizontal distance of the lingual plate to the nerve, on average, was 4.4 mm (SD 2.4 mm). The distance from the LN and the lingual alveolar rim, which represents the vertical relationship between the nerve and the lingual alveolar rim of the third molar socket, on average, was 16.8 mm (SD 5.7 mm). The LN has a varied topography that leaves it very vulnerable during any procedure executed in this region. Conclusions Unless adequate protection of the lingual nerve is acquired by following an adequate surgical technique, the lingual nerve will always be vulnerable to damage during surgical intervention or manipulation in this region.

de Carvalho Leite Leal Nunes, Carla Maria; de Almeida Lopes, Maria Candida

2013-01-01

413

Studies of the chronological course of third molars eruption in a northern Chinese population.  

PubMed

Dental age estimation is of great importance for individual identification in forensic medicine and many other fields of study. Among them, tooth eruption is a parameter developmental morphology that can be determined by clinical examinations or by dental X-rays. The purpose of present research is to study the chronological course of third molars eruption in a Chinese population and compare that with other ethnic population for age estimation. A total of 1135 conventional orthopantomograms from 506 male and 629 female northern Chinese subjects aged between 11 and 26 years were analyzed. The eruption status of the third molars was assessed using the developmental stages described by Olze et al. Results showed that the third molars 18, 28, 38 and 48 in the stage A showed significant younger average age in males than in females. The Olze's stage A could be used as a reference stage to determine whether a male or female northern Chinese is likely to be equal or above age 16, with 99.6-100% and 97.4-98.1% of correct predictions, respectively. The stage D was found to be a useful marker for diagnosing age under 16 years, with 98.9-100% and 100% of correct predictions in males and females, respectively. There were some significant differences of the chronological course of the third molars eruption in different ethnic groups, which indicated that population-specific standards could enhance the accuracy of forensic age estimation based on third molar eruption. PMID:24907520

Guo, Yu-Cheng; Yan, Chun-Xia; Lin, Xing-Wei; Zhou, Hong; Pan, Feng; Wei, Lai; Tang, Zheng; Liang, Feng; Chen, Teng

2014-09-01

414

Brief communication: possible third molar impactions in the hominid fossil record.  

PubMed

Impacted third molars affect 15%-20% of modern Americans and Western Europeans. In contrast, third molar impactions have not been reported in the early hominid fossil record. It is uncertain whether the lack of reports reflects an absence of impactions or a failure to recognize them. This communication is intended to raise awareness of the possibility of impactions by describing the appearance of impacted teeth and by noting two possible instances of impaction in early hominids. Specifically, the mandibular third molars of the Sterkfontein specimen, STS52b (Australopithecus africanus), and the left maxillary third molar of the Lake Turkana specimen, KNM-WT 17400 (Australopithecus boisei), are positioned in a manner which suggests that they would not have erupted normally. Both specimens also exhibit strong crowding of the anterior dentition, providing further support for the view that these individuals lacked sufficient space for normal eruption of the third molars. Other published reports of dental crowding in the hominid fossil record are noted, and it is suggested that more attention be paid to dental impaction and dental crowding in hominid evolution. PMID:8372939

Gibson, K R; Calcagno, J M

1993-08-01

415

The chronological age estimation of third molar mineralization of Han population in southwestern China.  

PubMed

The purpose of the study was to estimate the chronology of third molar mineralization in Han population of southwestern China and find its unique characteristics so that it would provide a reference in several legal cases like forensic age estimation. The study used Demirjian's staging method to study 2192 orthopantomograms of 984 male and 1208 female subjects aged between 8 and 25 years. The statistical data was analyzed by Student's t test and ANOVA. The conclusions of the study are: (1) The chronological mineralization age of third molars of Han population in Southwestern China is similar to the Turkish and the Japanese, was earlier than the Austrian and Han of South China, but later than the Spanish. (2) The mineralization timing of the third molars between two sides in maxilla or mandible has no significant differences in the same gender group. (3) There is no significant difference in mineralization of third molars between male and female, except for tooth 48 in Demirjian's stage E. (4) The mineralization of third molar in maxilla is earlier than mandible. PMID:24794846

Qing, Maofeng; Qiu, Lihua; Gao, Zhi; Bhandari, Kishor

2014-05-01

416

Molar tooth structures in calcareous nodules, early Neoproterozoic Burovaya Formation, Turukhansk region, Siberia  

NASA Astrophysics Data System (ADS)

Molar tooth structures are abundant in large (1-2 m diameter) carbonate nodules within fine-grained, subtidal carbonates of the early Neoproterozoic (lower Upper Riphean) Burovaya Formation along the Sukhaya Tunguska River, Turukhansk Uplift, northwestern Siberia. Although molar tooth structures are regionally abundant in this unit, here they occur only within the nodules. Stable isotopic compositions of molar-tooth-filling dolomicrospar cements and of thinly bedded dolomicrite within and surrounding the nodules are indistinguishable from one another. The carbon isotopic compositions (mean ?13C=+2.8‰ PDB±0.4) reflect mean average oceanic surface water composition during their formation; the light oxygen isotopic compositions (mean ?18O=-6.4‰ PDB±2.2) are generally similar to those of other little-altered Meso- to Neoproterozoic limestones and dolostones. These molar tooth structures have no features that would support a tectonic origin; they more likely formed through bacterial processes. Carbonate cement filling of these voids occurred soon after their formation, but the mechanism responsible for this carbonate precipitation is currently uncertain. Local restriction of molar tooth structures to early diagenetic nodules suggests that penecontemporaneous lithification was required for the formation, or at least preservation, of these widespread Mesoproterozoic to Neoproterozoic features.

Pope, Michael C.; Bartley, Julie K.; Knoll, Andrew H.; Petrov, Peter Yu.

2003-05-01

417

Cross-sectional study of correlation between mandibular incisor crowding and third molars in young Brazilians  

PubMed Central

Objectives: The aim of this study was to evaluate transversally the clinical correlation between lower incisor crowding and mandible third molar. Study Design: Three hundred healthy volunteers (134 male and 166 female), aged 20.4 (±2.4) years-old were submitted to a complete clinical examination and filled up a questionnaire about gender, age, total teeth number and presence or absence of superior and inferior third molar. After a recent panoramic radiography were evaluated. The multiple logistic regression showed that none of the studied factors influenced the mandibular incisor crowding. Results: The proportion of both molars present or both absent was higher than the other conditions (Chi-square, p<.0001). The multiple logistic regression showed that any of the studied factors, influenced (p>.05) the mandibular incisor crowding. Despite the statistical significance, wear orthodontics appliances showed a little correlation (odds ratios < 1.0) in the mandibular incisor crowding. Conclusion: Presence of maxillary and/or mandibular third molars has no relation with the lower incisor crowding. Key words:Malocclusion, third molars, lower incisor crowding, mandible.

Karasawa, Lilian H.; Groppo, Francisco C.; Prado, Felippe B.; Caria, Paulo H F.

2013-01-01

418

Ectopic third molar in the mandibular condyle: A review of the literature  

PubMed Central

Objectives: To evaluate the etiopathogenesis, clinical features, therapeutic options, and surgical approaches for removal of ectopic third molars in the mandibular condyle. Study design: MEDLINE search of articles published on ectopic third molars in the mandibular condyle from 1980 to 2011. 14 well-documented clinical cases from the literature were evaluated together with a new clinical case provided by the authors, representing a sample of 15 patients. Results: We found a mean age at diagnosis of 48.6 years and a higher prevalence in women. In 14 patients, associated radiolucent lesions were diagnosed on radiographic studies and confirmed histopathologically as odontogenic cysts. Clinical symptoms were pain and swelling in the jaw or preauricular region, trismus, difficulty chewing, cutaneous fistula and temporomandibular joint dysfunction. Treatment included conservative management in one case and in the other cases, surgical removal by intra- or extraoral approaches, the latter being the most common approach carried out. In most reported cases, serious complications were not outlined. Conclusions: The etiopathogenic theory involving odontogenic cysts in the displacement of third molars to the mandibular condyle seems to be the most relevant. They must be removed if they cause symptoms or are associated with cystic pathology. The surgical route must be planned according to the location and position of the ectopic third molar, and the possible morbidity associated with surgery. Key words:Third molar, ectopic tooth, condyle, mandible.

Iglesias-Martin, Fernando; Torres-Carranza, Eusebio; Prats-Golczer, Victoria-Eugenia; Garcia-Perla-Garcia, Alberto

2012-01-01

419

Partially segmented deformable mirror  

DOEpatents

A partially segmented deformable mirror is formed with a mirror plate having a smooth and continuous front surface and a plurality of actuators to its back surface. The back surface is divided into triangular areas which are mutually separated by grooves. The grooves are deep enough to make the plate deformable and the actuators for displacing the mirror plate in the direction normal to its surface are inserted in the grooves at the vertices of the triangular areas. Each actuator includes a transducer supported by a receptacle with outer shells having outer surfaces. The vertices have inner walls which are approximately perpendicular to the mirror surface and make planar contacts with the outer surfaces of the outer shells. The adhesive which is used on these contact surfaces tends to contract when it dries but the outer shells can bend and serve to minimize the tendency of the mirror to warp. 5 figures.

Bliss, E.S.; Smith, J.R.; Salmon, J.T.; Monjes, J.A.

1991-05-21

420

Partially segmented deformable mirror  

DOEpatents

A partially segmented deformable mirror is formed with a mirror plate having a smooth and continuous front surface and a plurality of actuators to its back surface. The back surface is divided into triangular areas which are mutually separated by grooves. The grooves are deep enough to make the plate deformable and the actuators for displacing the mirror plate in the direction normal to its surface are inserted in the grooves at the vertices of the triangular areas. Each actuator includes a transducer supported by a receptacle with outer shells having outer surfaces. The vertices have inner walls which are approximately perpendicular to the mirror surface and make planar contacts with the outer surfaces of the outer shells. The adhesive which is used on these contact surfaces tends to contract when it dries but the outer shells can bend and serve to minimize the tendency of the mirror to warp.

Bliss, Erlan S. (Danville, CA); Smith, James R. (Livermore, CA); Salmon, J. Thaddeus (Livermore, CA); Monjes, Julio A. (San Ramon, CA)

1991-01-01

421

Fuchsian Partial Differential Equations  

NASA Astrophysics Data System (ADS)

It is generally believed that our cosmos started with an initial singularity, the big bang. In fact all solutions of Einstein equations with compact spacelike sections present a singularity, at least in one time direction, except if the space is the flat three torus. The behavior near the singularity, chaotic or not, is a subject of active research. A case amenable to rigorous mathematical treatment is when the difference of the solution with a given spacetime metric satisfies a Fuchsian system of partial differential equations. In this article we give a more general definition than Kichenassamy and Rendall of a Fuchsian system and give a simpler proof of existence of solutions tending to zero at the singularity. Our generalization is interesting for Hamiltonian systems, as pointed out by Thibault Damour and Sophie de Buyl [10].

Choquet-Bruhat, Yvonne

2008-04-01

422

Shear modulus estimation using parallelized partial volumetric reconstruction  

Microsoft Academic Search

Magnetic resonance elastography can be limited by the computationally intensive nonlinear inversion schemes that are sometimes employed to estimate shear modulus from externally induced internal tissue displacements. Consequently, we have developed a parallelized partial volume reconstruction approach to overcome this limitation. In this paper, we report results from experiments conducted on breast phantoms and human volunteers to validate the proposed

Marvin M. Doyley; Elijah E. Van Houten; John B. Weaver; Steven P. Poplack; Laura Duncan; Francis E. Kennedy; Keith D. Paulsen

2004-01-01

423

A Histologic Study of the Width and Nature of Inter-radicular Spaces in Human Adult Pre-molars and Molars  

Microsoft Academic Search

Serial sections of jaw segments from a human post mortem population of 29 individuals providing 116 posterior interproximal sites were examined at the light microscopic level. Minimum inter-root distances at the locale of closest proximity ranged from more than 4 mm to less than 0.1 mm. They were located in the coronal third of pre-molars and mandibular first and second

P. J. Heins; S. M. Wieder

1986-01-01

424

First permanent molar: first indicator of dental caries activity in initial mixed dentition.  

PubMed

The objective of the present study was to investigate among children in the initial mixed dentition phase the presence of clinical signs that might eventually function as more sensitive indicators of the development of caries disease, denoted here as caries activity. On this basis, we investigated the relationship between salivary levels of mutans streptococci (MS) and decayed, missing and filled permanent and deciduous tooth surfaces (DMFS and dmfs) using microbiological, clinical and radiographic examinations in 81 schoolchildren aged 7-8 years. Whereas dmfs did not present a positive correlation, DMFS was significantly correlated with salivary MS levels. The first permanent molars of the schoolchildren studied comprised 87.3% of the affected surfaces recorded in the DMFS, suggesting that the development of new lesions was preferentially located on the surfaces of the first permanent molars. These results permit us to conclude that the first permanent molars function as first indicators of dental caries activity in the schoolchildren examined. PMID:10863396

Noronha, J C; Massara, M de L; Souki, B Q; Nogueira, A P

1999-01-01

425

Tuning of magnetic properties in cobalt ferrite by varying Fe+2 and Co+2 molar ratios  

NASA Astrophysics Data System (ADS)

Different grades of magnetic cobalt ferrite (CoFe2O4) nanoparticles were synthesized with various molar ratios of Fe+2 to Co+2 ions in the initial salt solutions by the co-precipitation method. The crystal structure and morphology of the nanoparticles are obtained from X-ray diffraction and transmission electron microscopy studies. Fourier transform infrared spectroscopy analysis exhibited the Fe-O stretching vibration ~540 cm-1, confirming the formation of metal oxide. The magnetic studies demonstrate that all of the nanoparticles are superparamagnetic at 300 K. The saturation magnetization and coercivity of the CoFe2O4 nanoparticles are affected by the molar ratios of Fe+2 to Co+2 ions. Among all the synthesized nanoparticles, the system with 75:25 molar ratio of Fe+2 to Co+2 ions with a particle size of 13 nm showed a high magnetization of 90 emu/g.

Biswal, Dipti; Peeples, Brianna N.; Peeples, Caryn; Pradhan, Aswini K.

2013-11-01

426

Asymmetry in mesial root number and morphology in mandibular second molars: a case report  

PubMed Central

Ambiguity in the root morphology of the mandibular second molars is quite common. The most common root canal configuration is 2 roots and 3 canals, nonetheless other possibilities may still exist. The presence of accessory roots is an interesting example of anatomic root variation. While the presence of radix entomolaris or radix paramolaris is regarded as a typical clinical finding of a three-rooted mandibular second permanent molar, the occurrence of an additional mesial root is rather uncommon and represents a possibility of deviation from the regular norms. This case report describes successful endodontic management of a three-rooted mandibular second molar presenting with an unusual accessory mesial root, which was identified with the aid of multiangled radiographs and cone-beam computed tomography imaging. This article also discusses the prevalence, etiology, morphological variations, clinical approach to diagnosis, and significance of supernumerary roots in contemporary clinical dentistry.

Shetty, Shashit; Shekhar, Rhitu

2014-01-01

427

Lingual nerve injury after third molar removal: Unilateral atrophy of fungiform papillae  

PubMed Central

Background: Pain and sensory changes due to lingual nerve injury are one of the most common alterations that follow surgical removal of third molar. They are usually transient but other less common complications, such as the atrophy of fungiform papillae, have an uncertain prognosis. Case Description: We report a case of a 34-year-old woman who presented a unilateral lingual atrophy of fungiform papillae after third molar extraction accompanied by severe dysesthesia that altered her daily life significantly during the following months and how this complication evolved over time. We conducted a literature review on the different factors that can lead to a lingual nerve injury. Clinical Implications: The clinical evolution of temporary and permanent somatosensitve injuries is an important fact to take into consideration during the postoperative management because it will indicate the lesion prognosis. Key words:Lingual nerve, third molar removal, somatosensitive alteration, papillae atrophy, permanent injury, temporary injury.

de-Pablo-Garcia-Cuenca, Alba; Bescos-Atin, Maria S.

2014-01-01

428

Analysis of C-shaped canal systems in mandibular second molars using surgical operating microscope and cone beam computed tomography: A clinical approach  

PubMed Central

Aims: The study was aimed to acquire better understanding of C-shaped canal systems in mandibular second molar teeth through a clinical approach using sophisticated techniques such as surgical operating microscope and cone beam computed tomography (CBCT). Materials and Methods: A total of 42 extracted mandibular second molar teeth with fused roots and longitudinal grooves were collected randomly from native Indian population. Pulp chamber floors of all specimens were examined under surgical operating microscope and classified into four types (Min's method). Subsequently, samples were subjected to CBCT scan after insertion of K-files size #10 or 15 into each canal orifice and evaluated using the cross-sectional and 3-dimensional images in consultation with dental radiologist so as to obtain more accurate results. Minimum distance between the external root surface on the groove and initial file placed in the canal was also measured at different levels and statistically analyzed. Results: Out of 42 teeth, maximum number of samples (15) belonged to Type-II category. A total of 100 files were inserted in 86 orifices of various types of specimens. Evaluation of the CBCT scan images of the teeth revealed that a total of 21 canals were missing completely or partially at different levels. The mean values for the minimum thickness were highest at coronal followed by middle and apical third levels in all the categories. Lowest values were obtained for teeth with Type-III category at all three levels. Conclusions: The present study revealed anatomical variations of C-shaped canal system in mandibular second molars. The prognosis of such complex canal anatomies can be improved by simultaneous employment of modern techniques such as surgical operating microscope and CBCT.

Chhabra, Sanjay; Yadav, Seema; Talwar, Sangeeta

2014-01-01

429

The distribution and ultrastructure of the forming blood capillaries and the effect of apoptosis on vascularization in mouse embryonic molar mesenchyme.  

PubMed

Vascularization is essential for organ and tissue development. Teeth develop through interactions between epithelium and mesenchyme. The developing capillaries in the