Biomedical subjects

C Rosenblatt

Publications and source records attributed to C Rosenblatt.

At least 19 recordsLinked to original sources

PubMed2006

A randomised, double-blind study comparing the efficacy and tolerability of controlled-release doxazosin and tamsulosin in the treatment of benign prostatic hyperplasia in Brazil.

Brazilian patients with benign prostatic hyperplasia were randomised in a 12-week, double-blind, double-dummy study to receive doxazosin gastrointestinal therapeutic system (GITS) 4 mg q.i.d. (n = 82) or tamsulosin 0.4 q.i.d. (n = 83). Primary endpoints were the absolute and percentage change from baseline in symptoms measured by International Prostate Symptom Score (IPSS). Secondary endpoints included IPSS, quality-of-life (QOL) question from the IPSS, and questions 6 and 7 of the Sexual Function Abbreviated Questionnaire (SFAQ) at weeks 4 and 12. Doxazosin GITS and tamsulosin improved IPSS with no significant differences between groups at week 12. During weeks 4-8, tamsulosin-treated patients demonstrated a slower improvement (p < 0.001) in IPSS than doxazosin GITS-treated patients. The proportion of satisfied patients was observed earlier with doxazosin GITS (p = 0.006) vs. tamsulosin. At week 12, the proportion of patients with little or no difficulty at ejaculation (Q6 of SFAQ) was higher in the doxazosin GITS group (p = 0.019). Both treatments were well tolerated.

Adrenergic alpha-Antagonists↗

PubMed2004

HPV prevalence among partners of women with cervical intraepithelial neoplasia.

OBJECTIVES: The objective of this study was to find HPV DNA incidence in women with CIN and normal women and in their respective partners, as well as the relation between the virus groups found in women with CIN or normal women and in their respective partners. METHODS: Partners of 30 women with CIN at several grades and of 60 normal women were prospectively assessed. In men, HPV search was performed by collecting samples through penile scraping for Hybrid Capture, followed by peniscopic evaluation and biopsy of acetowhite lesions. RESULTS: The presence of HPV DNA in male partners does not necessarily implicate the presence of HPV or even CIN in their female partners. CONCLUSIONS: If these results are confirmed by other authors, obtaining a peniscopy, a penile biopsy, and a HPV DNA search in partners that present with no clinical lesions, but in couples with women having CIN, would not be warranted.

Chi-Square Distribution↗

PubMed2001

Velocity of an electric-field-induced synclinic solitary wave invading the anticlinic liquid crystal phase.

The electric-field dependence of the velocity of synclinic fingers invading the anticlinic phase is determined by a time-of-flight technique. The time delay for a rapid increase in the transmitted optical intensity through the sample is measured between two points as a function of their separation along the trajectory of the solitary wave. The data are quantitatively consistent with the rapid velocities deduced from a previous measurement [Liq. Cryst. 27, 249 (2000)], demonstrating that the previous data were not affected by multiple nucleation sites occurring at higher fields.

Journal Article↗

PubMed2000

Freedericksz transition in an anticlinic liquid crystal

It is shown experimentally that a very-long-pitch, surface-stabilized, anticlinic liquid crystal undergoes a two-step electric-field-induced transition to the synclinic phase. The liquid crystal remains undistorted below a threshold field E(th). For E>E(th), a Freedericksz transition occurs, wherein molecules in adjacent smectic layers undergo unequal azimuthal rotations about the layer normal. At higher fields a transition to the synclinic phase occurs via solitary waves.

Journal Article↗

PubMed2000

Collapse dynamics of liquid bridges investigated by time-varying magnetic levitation

Using a novel technique that facilitates temporal control over the total body force on a liquid, an unexpected scaling relationship was discovered for the collapse time of a liquid bridge. A paramagnetic liquid was suspended between the tips of two collinear rods in a strong magnetic field gradient that was adjusted to compensate gravity. A sudden change of the magnet current, corresponding to a change of Bond number, resulted in a deformation and ultimate collapse of the liquid bridge. The collapse time was found to be independent of the bridge length when other parameters were held constant.

Journal Article↗

PubMed2000

Bend elasticity of mixtures of V-shaped molecules in ordinary nematogens

Freedericksz measurements were performed on mixtures of a nematic mesogen and a V-shaped molecule. The bend elastic constant was found to decrease significantly with increasing concentration of the V-shaped molecule. The results are discussed theoretically, taking into account the detailed structure of the molecules.

Journal Article↗

PubMed2000

Interlayer interactions in enantiomeric anticlinic liquid crystalline mixtures

The interlayer interaction coefficient U in the anticlinic phase of enantiomeric binary mixtures was determined by measuring the threshold electric field for the onset of solitary waves. U was found to increase with decreasing temperature in the anticlinic phase for a given enantiomer excess X. The ratio U(X,straight theta)/U(X=1,straight theta), where straight theta is the polar angle, was found to be significantly smaller for mixtures with low enantiomer excess than for the optically pure material. The observed behavior is analyzed using a mean-field model for dipole-dipole interactions in adjacent layers.

Journal Article↗

PubMed2000

Freedericksz transition in an anticlinic liquid crystal

The Freedericksz geometry is used to show experimentally that a very-long-pitch, surface stabilized, anticlinic liquid crystal undergoes a two-step electric-field-induced transition to the synclinic phase. The liquid crystal remains undistorted below the threshold field E(th). For E>E(th), a Freedericksz transition occurs, wherein molecules in adjacent smectic layers undergo unequal azimuthal rotations about the layer normal, resulting in a nonzero polarization that couples to the applied field. Measurements of E(th) as a function of temperature are reported. Related quasielastic light scattering measurements demonstrate that acoustic Goldstone mode fluctuations are quenched by a dc electric field E>E(th). At high fields a transition to the synclinic phase occurs via solitary waves.

Journal Article↗

PubMed2000

Electric field-induced acoustic-optic mode coupling in an anticlinic liquid crystal

A dc electric field was applied perpendicular to the tilt plane of a pitch-compensated (unwound helix) anticlinic liquid crystal. By means of quasielastic light scattering, the field was found to couple the acoustic and optic Goldstone modes, resulting in an increase of the relaxation time tau(beta) of the acousticlike eigenmode. Elastic constants were estimated from the relaxation time data.

Journal Article↗

PubMed1999

Stability of Magnetically Levitated Liquid Bridges of Arbitrary Volume Subjected to Axial and Lateral Gravity.

The paramagnetic fluid composed of manganese chloride tetrahydrate dissolved in water was used to form bridges held between two parallel collinear rods. Magnetic levitation was used to control the effective gravity felt by the bridges. Their stability was studied as a function of Bond number and volume of the supported liquid. Data are compared with theoretical predictions for liquid bridges as well as with experimental results, where available. Copyright 1999 Academic Press.

Journal Article↗

PubMed1999

Anticlinic coupling between layers of an antiferroelectric liquid crystal.

The anticlinic interlayer coupling coefficient U was evaluated as a function of temperature for a pitch-compensated liquid crystal by optical observation of the electric field-induced optic mode. U was found to exhibit an unusual "S-shaped" dependence on temperature, with values ranging between 0.4x10(4) and 2.2x10(4) erg cm(-3) over a 10 degrees C temperature range below the smectic-A-smectic-C(*)(A) phase-transition temperature. The results are in good agreement with estimates for U based upon the threshold field for the onset of solitary waves, and provide strong support in the low-field regime for the single Fourier component model proposed by Li et al. [Phys. Rev. B 52, R13 075 (1995)].

Journal Article↗

PubMed1999

Pretransitional behavior above the nematic-isotropic phase transition of an auxetic trimer liquid crystal.

Static light scattering and electric field-induced Kerr measurements were performed above the nematic-isotropic phase transition of a terminal-lateral-lateral-terminal negative Poisson ratio trimer. For both measurements the inverse susceptibility was observed to be nearly linear with temperature, a result inconsistent with our previously reported Kerr data [Phys. Rev. E 58, 2041 (1998)].

Journal Article↗

PubMed1999

Electro-optic response of surface-induced nematic order above the nematic-isotropic phase transition temperature.

The optical retardation of a liquid crystal above the nematic-isotropic phase transition temperature T(NI) and subjected to planar alignment conditions at the substrate was investigated in the presence of an electric field applied normal to the substrates. The response was found to exhibit "S"-shaped behavior with electric field, and was larger near T(NI) than well above T(NI). The results were examined in the context of a model that permits both biaxiality and a field-induced tilt of the molecular director. The results suggest that the primary effect of the electric field is to induce biaxiality, and in consequence suppress the order induced by the surface. No clear indication of a Freedericksz-like transition, either experimental or theoretical, was observed.

Journal Article↗

PubMed1999

Nematic order in nanoscopic liquid crystal droplets.

We have used atomistic molecular-dynamics simulations to model the detailed molecular configuration of 5CB (4-n-pentyl-4'-cyanobiphenyl) molecules in the form of a nanoscopic liquid crystal droplet in a vacuum microgravity environment. We find the equilibrium state of droplets consisting of as few as 26 or 50 molecules to exhibit significant nematic ordering. The shape of the droplets is also anisotropic, but there is little angular correlation between the nematic director and the long axis of the droplet. Some tendency to micelle formation is observed in droplets of 50 molecules.

Journal Article↗

PubMed1996