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Condensing osteitis of the clavicle: MRI.

PURPOSE: Condensing osteitis of the clavicle is a rare benign disorder, seen exclusively in women and characterized by expansion and sclerosis of the medial end of the clavicle. The aim of this study was to evaluate the MR findings of this disorder. METHOD: MR images, obtained in four patients with evidence of condensing osteitis of the clavicle based on plain radiographs and clinical symptoms, included pre- and postcontrast T1 SE sequences, T2 SE images, GE images. RESULTS: MR images revealed consistent hypointense areas on T1-weighted SE images, corresponding to regions of clavicular sclerosis (n = 4). T2-weighted SE images showed signal characteristics ranging from low intermediate signal intensity in regions of sclerosis (n = 4). T2-weighted GE images revealed moderate to high signal intensity presumably related to bone marrow edema (n = 2). Contrast-enhanced T1-weighted SE images were characterized by mild to extensive intraosseous and periosseous enhancement of signal intensity (n = 2). CONCLUSION: MRI in cases of condensing osteitis of the clavicle reveals variable findings perhaps indicative of different stages of activity in this disease.

Adult↗

PubMed2001

Effect of spreader and accessory cone size on density of obturation using conventional or mechanical lateral condensation.

A simulated curved root canal in a resin block was enlarged to size 40 and used to compare the depth of accessory cone penetration and weight of obturation occurring with the use of different obturation techniques and spreader-accessory cone combinations. Twelve groups, each consisting of 10 obturations, were created. A conventional lateral condensation technique was used in six groups and a mechanical lateral condensation (MLC) technique was used in six matched groups. The six spreader-accessory cone combinations were either Fine-Medium or Fine nickel-titanium finger spreaders with either Fine, Medium-Fine, or size 25 accessory cones. Seven accessory cones were placed in every obturation. The depth of each accessory cone penetration into the canal was measured. After each obturation the gutta-percha was removed, sectioned, and the resulting mass was weighed. The means for each variable were determined and compared. MLC fills were significantly heavier and had greater depth of penetration on average than conventional lateral condensation. The best combination for heavy fills was MLC, Fine-Medium spreaders, and Fine accessory cones. The greatest mean accessory cone depth occurred with MLC, Fine-Medium spreaders, and size 25 accessory cones.

Analysis of Variance↗

PubMed2004

A comparison of laterally condensed gutta-percha, thermoplasticized gutta-percha, and mineral trioxide aggregate as root canal filling materials.

The purpose of this study was to evaluate the potential of using mineral trioxide aggregate as a root canal filling material by comparing its apical sealing ability with that of laterally condensed gutta-percha with sealer and high-temperature thermoplasticized gutta-percha with sealer in extracted bovine teeth. Sixty bovine incisors with single canals were prepared in a standard manner using LightSpeed instruments, randomly divided into three groups of 20 teeth, and obturated. The sealing ability of each technique was assessed by immersion in 1% methylene blue dye for 3 days. The teeth were cleared, and the linear extent of dye penetration was measured with a stereomicroscope. Data were analyzed by the Kruskal-Wallis one-way ANOVA followed by Dunn's test. Canals filled with laterally condensed gutta-percha or thermoplasticized gutta-percha showed significantly less apical dye penetration than canals obturated with mineral trioxide aggregate (p < 0.001). There was no significant difference in leakage between the laterally condensed group and the thermoplasticized group. The results suggest that gutta-percha obturation may provide an apical seal that is superior to MTA.

Aluminum Compounds↗

PubMed1997

Estimation of condensed pulmonary parenchyma from gas exchange parameters in patients with multiple trauma and blunt chest trauma.

Pulmonary gas exchange in correlation with condensed lung volume was prospectively studied in 10 patients with multiple injuries and blunt chest trauma. The purpose was to find nomograms that allow the estimation of the extent of pulmonary density from gas exchange parameters. The condensed lung volume was determined planimetrically from serial transverse sections of chest computed tomographic scans. There was no correlation between condensed lung volume and mean pulmonary artery pressure, pulmonary vascular resistance, systemic vascular resistance, or cardiac index and a week negative correlation to the oxygenation index (PaO2/FIO2) (r2 = 0.46) and to the total static lung compliance (r2 = 0.29). A strong correlation between pulmonary density and intrapulmonary shunt fraction (Qs/Qt) (r2 = 0.95) as well as alveoloarterial PO2 difference (P[A-a]O2) (r2 = 0.86) was evident. By using linear regression equations (linear regression line with 95% confidence interval), nomograms were calculated. The extent of pulmonary density can easily be obtained from these nomograms by measuring Qs/Qt or P(A-a)O2. The presented nomograms may be helpful in monitoring the effect of treatment in patients with blunt chest trauma.

Adolescent↗

PubMed1999

Fission yeast condensin complex: essential roles of non-SMC subunits for condensation and Cdc2 phosphorylation of Cut3/SMC4.

The condensin complex in frog extracts, containing two SMC (structural maintenance of chromosomes) and three non-SMC subunits, promotes mitotic chromosome condensation, and its supercoiling activity increases during mitosis by Cdc2 phosphorylation. Here, we report that fission yeast has the same five-member condensin complex, each of which is essential for mitotic condensation. The condensin complex was purified and the subunits were identified by microsequencing. Cnd1, Cnd2, and Cnd3, three non-SMC subunits showing a high degree of sequence conservation to frog subunits, are essential for viability, and their gene disruption leads to a phenotype indistinguishable from that observed in cut3-477 and cut14-208, known mutations in SMC4 and SMC2-like subunits. Condensin subunits tagged with GFP were observed to alter dramatically their localization during the cell cycle, enriched in the nucleus during mitosis, but cytoplasmic during other stages. This stage-specific alteration in localization requires mitosis-specific phosphorylation of the T19 Cdc2 site in Cut3. The T19 site is phosphorylated in vitro by Cdc2 kinase and shows the maximal phosphorylation in metaphase in vivo. Its alanine substitution mutant fails to suppress the temperature-sensitive phenotype of cut3-477, and shows deficiency in condensation, probably because Cut3 T19A remains cytoplasmic. Therefore, direct Cdc2 phosphorylation of fission yeast condensin may facilitate its nuclear accumulation during mitosis.

Amino Acid Sequence↗

PubMed2000

Ionic condensation theories and the liquidlike structures observed in colloidal dispersions

Though the notion of effective charge has been widely used to fit experimental data, the possibility of predicting this adjustable parameter through a model remains unclear. A likely reason for this is the complexity involved in the theoretical approaches in the case of fluids with large asymmetries between their components. This paper deals with several condensation theories for spherical colloids, developed to provide effective charge values from simple models. Liquidlike structures are formed in colloidal dispersions for a set of latexes with different properties (charge, size, and polymeric composition). Effective charges are determined from experimental structure factors using a Derjaguin-Landau-Verwey-Overbeek potential and an Ornstein-Zernike scheme. The numerical coincidence between effective and post-condensation charges is fairly acceptable only for latexes with small size and charge. A simple approach based on the Manning condensation theory for linear polyelectrolytes is also discussed.

Journal Article↗

PubMed2000

Ground state of trapped interacting bose-einstein condensates by an explicit imaginary-time algorithm

We show that an explicit time-marching method previously developed for the numerical study of the dynamics of Bose-Einstein condensates can be profitably adapted to the numerical determination of their ground state. After reduction to a one-dimensional model, we first reproduce and test known results on condensates in harmonic traps and then determine the ground state of a condensate in a harmonically bound optical lattice in the range of parameters which are relevant to existing experiments.

Journal Article↗

PubMed2001

Stability of repulsive Bose-Einstein condensates in a periodic potential.

The cubic nonlinear Schrödinger equation with repulsive nonlinearity and an elliptic function potential models a quasi-one-dimensional repulsive dilute gas Bose-Einstein condensate trapped in a standing light wave. New families of stationary solutions are presented. Some of these solutions have neither an analog in the linear Schrödinger equation nor in the integrable nonlinear Schrödinger equation. Their stability is examined using analytical and numerical methods. All trivial-phase stable solutions are deformations of the ground state of the linear Schrödinger equation. Our results show that a large number of condensed atoms is sufficient to form a stable, periodic condensate. Physically, this implies stability of states near the Thomas-Fermi limit.

Journal Article↗

PubMed2002

Influence of boundary conditions on statistical properties of ideal Bose-Einstein condensates.

We investigate the probability distribution that governs the number of ground-state particles in a partially condensed ideal Bose gas confined to a cubic volume within the canonical ensemble. Imposing either periodic or Dirichlet boundary conditions, we derive asymptotic expressions for all its cumulants. Whereas the condensation temperature becomes independent of the boundary conditions in the large-system limit, as implied by Weyl's theorem, the fluctuation of the number of condensate particles and all higher cumulants remain sensitive to the boundary conditions even in that limit. The implications of these findings for weakly interacting Bose gases are briefly discussed.

Journal Article↗

PubMed2003

Phase transitions and quantum effects in pore condensates: a path integral Monte Carlo study.

Lennard-Jones condensates in cylindrical pores are studied by path integral Monte Carlo simulations with particular emphasis on phase transitions and quantum effects. The pore diameter effect and the influence of the interaction strength between the cylinder wall and the adsorbate particles on the structures and the location of the phase boundaries is studied and the quantum effect on the phase diagram is quantified by path integral Monte Carlo simulations. In case of strong wall-particle interactions good qualitative agreement with recent experimental results for the freezing of Ar-pore condensates is found. Meniscus structures in the solid phase are obtained as well as unexpected condensate structures for the system with the lighter Ne-particles due to quantum delocalization effects. The quantum effect on the freezing temperature can be as large as 10% in these systems.

Journal Article↗

PubMed2003

Selective counterion condensation in ionic micellar solutions.

Small-angle neutron scattering experiments have been carried out on micellar solutions of cationic surfactants of cetyltrimethylammonium bromide (CTABr) and chloride (CTACl) in the presence of varying concentrations of salts KBr and KCl. In these systems, while the size of micelles strongly increases with the addition of KBr, the effect of addition of KCl in comparison is much less pronounced. It is found that in equimolar surfactant to salt micellar solutions of CTABr/KCl and CTACl/KBr, the micellar sizes are larger in CTACl/KBr than those in CTABr/KCl. The measurements have been done for different equimolar surfactant to salt concentrations and at different temperatures. We explain these results in terms of selective counterion condensation on the micelles. That is, while the condensation of Cl- counterions on the CTABr micelles in CTABr/KCl takes place around the condensed Br- counterions of CTABr, the Cl- counterions of CTACl in CTACl/KBr are replaced by Br- counterions of the salt. Similar results have also been obtained on micellar solutions of anionic surfactants of sodium dodecyl sulfate and lithium dodecyl sulfate in the presence of salts LiBr and NaBr, respectively.

Journal Article↗

PubMed2005

Interacting particles on a rocked ratchet: rectification by condensation.

The transport of interacting particles subject to an external low-frequency ac force on a ratchetlike asymmetric substrate is studied via a nonlinear Fokker-Planck equation as well as via numerical simulations. With increasing the particle density, the ratchet current can either increase or decrease depending on the temperature, the drive amplitude, and the nature of the interparticle interaction. At low temperatures, attracting particles can condense randomly at some potential minima, thus breaking the discrete translational symmetry of the substrate. Depending on the drive amplitude, condensation results either in a drop to zero or in the saturation of the net particle velocity at densities above the condensation density-the latter case producing a very efficient rectification mechanism.

Journal Article↗

PubMed2005

Controlling chaos in a weakly coupled array of Bose-Einstein condensates.

The spatial structure of a Bose-Einstein condensate loaded into an optical lattice potential is investigated and the spatially chaotic distributions of the condensates are revealed under the tight-binding approximation. Adding a laser pulse on a proper site of the lattice and treating it as a control signal, control of the chaos in the system is carried out by using the Ott-Grebogi-Yorker scheme. For an appropriate laser pulse, we can suppress the chaos and push the system onto a stable manifold of a target orbit. After the control, a regular distribution, which may be expected in experiments or practical applications, of the condensates in the coordinate space is obtained.

Journal Article↗

PubMed2006

Condensation transitions in a model for a directed network with weighted links.

An exactly solvable model for the rewiring dynamics of weighted, directed networks is introduced. Simulations indicate that the model exhibits two types of condensation: (i) a phase in which, for each node, a finite fraction of its total out-strength condenses onto a single link; (ii) a phase in which a finite fraction of the total weight in the system is directed into a single node. A virtue of the model is that its dynamics can be mapped onto those of a zero-range process with many species of interacting particles--an exactly solvable model of particles hopping between the sites of a lattice. This mapping, which is described in detail, guides the analysis of the steady state of the network model and leads to theoretical predictions for the conditions under which the different types of condensation may be observed. A further advantage of the mapping is that, by exploiting what is known about exactly solvable generalizations of the zero-range process, one can infer a number of generalizations of the network model and dynamics which remain exactly solvable.

Journal Article↗

PubMed2006

Dynamics of capillary condensation in aerogels.

Dynamics of capillary condensation of liquid 4He in various density silica aerogels was investigated systematically. Interfaces were clearly visible when bulk liquid was rapidly sucked into the aerogel. Time evolution of the interface positions was consistent with the Washburn model and their effective pore radii were obtained. Condensation was a single step in a dense aerogel and two steps in a low density aerogel. Crossover between the two types of condensation was observed in an intermediate density aerogel. Variety of the dynamics may be the manifestation of the fractal nature of aerogels which had a wide range of distribution of pore radii.

Journal Article↗

PubMed2006

Dynamics of the Bose-Einstein condensation: analogy with the collapse dynamics of a classical self-gravitating Brownian gas.

We consider the dynamics of a gas of free bosons within a semiclassical Fokker-Planck equation for which we give a physical justification. In this context, we find a striking similarity between the Bose-Einstein condensation in the canonical ensemble, and the gravitational collapse of a gas of classical self-gravitating Brownian particles. The paper is mainly devoted to the complete study of the Bose-Einstein "collapse" within this model. We find that at the Bose-Einstein condensation temperature Tc, the chemical potential mu(t) vanishes exponentially with a universal rate that we compute exactly. Below Tc, we show analytically that square root mu(t) vanishes linearly in a finite time t coll. After t coll, the mass of the condensate grows linearly with time and saturates exponentially to its equilibrium value for large time. We also give analytical results for the density scaling functions, for the corrections to scaling, and for the exponential relaxation time. Finally, we find that the equilibration time (above Tc) and the collapse time T coll(below Tc) both behave like -T -3 c ln|T-Tc|, near Tc.

Journal Article↗

PubMed2000

Bose-einstein condensation in quasi-2D trapped gases

We discuss Bose-Einstein condensation (BEC) in quasi-2D trapped gases and find that well below the transition temperature T(c) the equilibrium state is a true condensate, whereas at intermediate temperatures T<T(c) one has a quasicondensate (condensate with fluctuating phase). The mean-field interaction in a quasi-2D gas is sensitive to the frequency omega(0) of the (tight) confinement in the "frozen" direction, and one can switch the sign of the interaction by changing omega(0). Variation of omega(0) can also reduce the rates of inelastic processes. This offers promising prospects for tunable BEC in trapped quasi-2D gases.

Journal Article↗

PubMed2000

Fragmented and single condensate ground states of spin-1 bose Gas

We show that the ground state of a spin-1 Bose gas with an antiferromagnetic interaction is a fragmented condensate in uniform magnetic fields. The number fluctuations in each spin component change rapidly from being enormous (order N) to exceedingly small (order 1) as the magnetization of the system increases. A fragmented condensate can be turned into a single condensate state by magnetic field gradients. The conditions for existence and method of detecting fragmented states are presented.

Journal Article↗