Search Results - (Author, Cooperation:L. Orozco)

2018-07-17

The American Association for Cancer Research (AACR)

1078-0432

1557-3265

Medicine

2014-01-07

Nature Publishing Group (NPG)

0028-0836

1476-4687

Biology

Chemistry and Pharmacology

Medicine

Natural Sciences in General

Physics

African Continental Ancestry Group/genetics ; Alleles ; Animals ; Asian Continental Ancestry Group/genetics ; Cohort Studies ; Diabetes Mellitus, Type 2/*genetics ; Endoplasmic Reticulum/genetics ; European Continental Ancestry Group/genetics ; Female ; Genetic Predisposition to Disease/*genetics ; Genome-Wide Association Study ; Haplotypes/genetics ; HeLa Cells ; Humans ; Indians, North American/genetics ; Lipid Metabolism/genetics ; Liver/cytology/metabolism ; Male ; Mexico ; Monocarboxylic Acid Transporters/*genetics ; Neanderthals/genetics ; Polymorphism, Single Nucleotide/*genetics ; RNA, Messenger/genetics/metabolism ; Triglycerides/metabolism

1089-7690

AIP Digital Archive

Physics

Chemistry and Pharmacology

Using the formalism of extended irreversible thermodynamics we derive the generalized constitutive equations for the polarization vector and the symmetric and antisymmetric parts of the total stress tensors (the sum of the Maxwell and viscous stress tensors) of a viscoelastic polar fluid. The analysis of these equations shows several interesting features for a permanent dipolar system. The diffusive transport of polarization charge and the diffusion of the transverse polarization component are two elementary physical processes in terms of which complex cases of dielectric relaxation can be described, taking into account both translational and rotational motions of the dipolar particles in a viscoelastic fluid. The calculations for several cases of the complex dielectric susceptibility are presented. In these results, the coupling between polarization and hydrodynamics predicts several modes of dielectric energy dissipation. These various channels are due to the intimate coupling between different degrees of freedom, taken into account by the constitutive equations. The calculation of the complex shear and rotational viscosities complete the presentation.

Electronic Resource

1089-7690

AIP Digital Archive

Physics

Chemistry and Pharmacology

The generalized evolution equations for the polarization vector and the total stress tensor (viscous plus Maxwell's electric stress tensors) are obtained in the framework of extended irreversible thermodynamics. The coupling of these equations represents the mutual influence between mechanical and dielectric properties of a viscoelastic and dielectric fluid. The dipolar memory and the associated correlation functions are discussed in order to give an understanding in the current way of thinking based on linear response theory. A comparison with studies of polarization charge diffusion is included as a particular result obtained from the generalized constitutive equations. Calculations of the complex electric susceptibility and the complex viscosity for the linear and incompressible case are presented.

Electronic Resource

1089-7666

AIP Digital Archive

Physics

The three-dimensional thermocapillary instability of a fluid film coating the outside or the inside of a cylinder is investigated in the absence and in the presence of gravity. In the absence of gravity (pure thermocapillarity), it is found that it is possible to excite high azimuthal modes as the most unstable. In the presence of gravity the thermocapillary instability of a thin fluid film flowing down a vertical cylinder is investigated. It is shown that thermocapillarity also promotes the instability of high azimuthal modes, even higher than those found in the pure thermocapillary case. This is in contrast with the isothermal case where only the zeroth mode (the longitudinal one) is the most unstable and also with previous work on flow down a rotating cylinder where, in some conditions, rotation may promote the first azimuthal mode as the most unstable. Curves of criticality and those corresponding to the maximum growth rate are given for different values of the parameters. © 2000 American Institute of Physics.

Electronic Resource

1089-7623

AIP Digital Archive

Physics

Electrical Engineering, Measurement and Control Technology

We report a method to monitor and control laser frequencies with an optical cavity and a digital feedback system. A frequency-stabilized He–Ne laser provides the reference that is transferred to several other lasers using a scanning Fabry–Pérot cavity. A personal computer-based multifunction data acquisition system generates the scan wave form, and reads the detector outputs synchronously with the cavity scan. The computer determines the positions of all of the peaks in the scan, and generates output signals to control the laser frequencies. It also provides a visual display of cavity spectra. We have successfully used the setup to achieve a long-term lock of the lasers for magneto-optical trapping of radioactive francium atoms. © 1998 American Institute of Physics.

Electronic Resource

1089-7666

AIP Digital Archive

Physics

A reply to the comments by Chakraborty and Tuteja [Phys. Fluids A 1, 1600 (1989)] is presented. After a careful review, it was found that their comments are correct. Despite this, the physical conclusions, for H=0, concerning the implications of the problem on natural convection under a horizontal magnetic field remain the same.

Electronic Resource

1089-7666

AIP Digital Archive

Physics

The linear stability of a fluid layer flowing down a rotating inclined plane is investigated. The analysis leads to a system of two coupled ordinary differential equations that generalizes the well-known Orr–Sommerfeld equation. These coupled equations are solved by means of two approximations: the small wave-number approximation and the small Reynolds number approximation. For the small wave-number approximation, it is shown that the Coriolis force not only may decrease the growth rate of the instability, but it may stabilize the flow for all angles of propagation of the perturbation. For the small Reynolds and Taylor numbers and small angle of inclination, it is shown that an increase in Taylor number may destabilize the fluid layer.

Electronic Resource

1089-7666

AIP Digital Archive

Physics

The Rayleigh–Taylor instability of a continuously stratified magnetofluid under a general rotation field and a vertically stratified horizontal magnetic field is investigated. The upper bound for the growth rate of the perturbation is found and corrections to that obtained by Chakraborty [Phys. Fluids 25, 743 (1982)] are given. The theory predicts the formation of rolls appearing in natural rotating convection and magnetoconvection.

Electronic Resource

1089-7666

AIP Digital Archive

Physics

An estimate of the upper bound of the growth rate of instability in a continuously unstable stratified fluid under a general rotation field is obtained. An example for exponential stratification is given. For magnitudes of the wavenumber k slightly above kc (where kc is the critical value for instability) it is shown that the angle of propagation for the perturbation associated to a maximum growth rate is θmax =0° (180°), where θmax is measured relative to a fixed horizontal component of rotation. For larger values of k bifurcation occurs with two maxima of the same magnitude appearing at angles different from θ=0° but symmetrically located. Increasing k leads to a unique maximum at θmax =90° (−90°). The bifurcation tends to disappear as the vertical component of rotation is increased.

Electronic Resource

1089-7690

AIP Digital Archive

Physics

Chemistry and Pharmacology

In this paper we calculate the complex dielectric constant of polar liquids for microwave and far-infrared range of frequencies. We use the formalism of extended irreversible thermodynamics (EIT) to obtain the autocorrelation function of the polarization vector. To this end, we introduce the local variation of the polarization flow as an independent variable, which allows for the description of collective interacting effects into the formalism. The results obtained here are compared with previous work in the so-called three-variable theory based on the Mori-Zwanzig projection operator technique. This comparison provides an interpretation of EIT in terms of a microscopic theory from which the role of the new independent variable can be established. Using the result of the complex dielectric constant presented here, we show that the fitting of experimental data in polar fluids can be improved in the far infrared frequencies. © 1997 American Institute of Physics.

Electronic Resource

1089-7666

AIP Digital Archive

Physics

In this paper the linear stability of a fluid layer flowing down the inside and outside of a rotating vertical cylinder is investigated. To this end, two approximations are made: the small wave number approximation and the small Reynolds number approximation. In the former, only the radial destabilizing effect of surface tension is important and may be counteracted by the centrifugal force at a critical value. In the latter, the analysis integrates the azimuthal modes different from m=0. It is shown that for flow outside the cylinder, the magnitude of centrifugal force and wave number may change the dominant mode of instability. For flow inside the cylinder, only the mode m=0 may be unstable. These results generalize those of Boudourides and Davis [Z. Angew. Math. Phys. 37, 597 (1986)] for swirling viscous flows.

Electronic Resource

0066-6742

Archaeology

NOTICIARIO

0378-1119

Escherichia coli ; Posttranscriptional controls ; bacteriophage λ ; reporter gene ; represser ; ribonucleases ; β-galactosidase

Elsevier Journal Backfiles on ScienceDirect 1907 - 2002

Biology

Electronic Resource

1745-4530

Blackwell Publishing Journal Backfiles 1879-2005

Process Engineering, Biotechnology, Nutrition Technology

A low-cholesterol shrimp was produced using supercritical extraction. The processing sequence included freeze drying, cholesterol extraction and rehydration. The shrimp was freeze dried, kept under vacuum until an experimental central composite rotatory design was applied using Response Surface Analysis for the supercritical extraction process. Three variables at five levels each were tested during the experiment (pressure, volume and temperature). After the extraction procedure, various rehydration and cooking conditions were applied to obtain a processed product with characteristics similar to those of the natural shrimp. Two sensory analyses were performed: one which compared the attributes of fresh shrimp with those of the freeze-dried and rehydrated products, and another one which compared the acceptability between fresh shrimp and low-cholesterol shrimp after freeze drying, supercritical extraction and rehydration. Under the conditions of 310 bar, 1875 L of carbon dioxide and 37C, it was possible to obtain a low-cholesterol shrimp with acceptable organoleptic properties.

Electronic Resource

1572-946X

47.20.Bp ; 47.55.Hd ; 47.65.+a

Springer Online Journal Archives 1860-2000

Physics

Abstract In this paper the Rayleigh-Taylor instability (RTI) of a two-fluid layer system under the simultaneous action of a general rotation field and a horizontal magnetic field is presented. An approximate and an exact solution of the eigenvalue equation are calculated. These solutions are important not only to understand more deeply the physical problem but also to determine the correct numerical solutions. Numerical calculations are done for an unstable density stratification in the cases of horizontal magnetic field parallel and perpendicular to the horizontal component of the angular velocity. For an adverse density stratification, it is shown that in comparison to previous works, the horizontal magnetic field creates new angular areas (of the angle of propagation of the perturbation) at which the perturbation is stable and propagates as traveling waves. It is also shown that the vertical component of the angular velocity has a destabilizing effect because it works to eliminate the stable angular areas.

Electronic Resource

0093-691X

Elsevier Journal Backfiles on ScienceDirect 1907 - 2002

Medicine

Electronic Resource

1432-1203

Springer Online Journal Archives 1860-2000

Biology

Medicine

Abstract. We have analyzed 97 CF unrelated Mexican families for mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene. Our initial screening for 12 selected CFTR mutations led to mutation detection in 56.66% of the tested chromosomes. In patients with at least one unknown mutation after preliminary screening, an extensive analysis of the CFTR gene by single stranded conformation polymorphism (SSCP) or by multiplex heteroduplex (mHET) analysis was performed. A total of 34 different mutations representing 74.58% of the CF chromosomes were identified, including five novel CFTR mutations: W1098C, P750L, 846delT, 4160insGGGG and 297–1G→A. The level of detection of the CF mutations in Mexico is still lower than that observed in other populations with a relatively low frequency of the ΔF508 mutation, mainly from southern Europe. The CFTR gene analysis described here clearly demonstrated the high heterogeneity of our CF population, which could be explained by the complex ethnic composition of the Mexican population, in particular by the strong impact of the genetic pool from southern European countries.

Electronic Resource

1572-9540

Springer Online Journal Archives 1860-2000

Physics

Abstract An experimental program is under way to capture neutral francium atoms in a magneto-optic trap. Production and transport of the radioactive Fr atoms near to the trapping region have been tested, with a steady state of 107 atoms. If one hundred atoms are captured from the Maxwell-Boltzmann distribution into a magneto-optic trap, this will be a sufficient number for spectroscopy of the unknown excited states. These measurements would then open the path to investigations of parity-violating transitions in francium.

Electronic Resource

1572-9540

Springer Online Journal Archives 1860-2000

Physics

Abstract Laser spectroscopic observations of nuclear reaction products produced with intensities of less than 104 atoms/second are now possible with several different methods. We describe the recoil into gas method which has recently been successful. This method is not Dopplerfree, but can give reasonable spectra if the resolution requirements of the spectra are not too high. It has the great advantage that it very efficiently uses the atoms, and spectra have been observed with primary production rates of less than 103 atoms/sec. Our recent work has concentrated on developing the recoil into gas method for the refractory element Hf. In order that the atoms could be cycled to produce many fluorescence photons, nitrogen and hydrogen impurity gases were added to the argon buffer gas to quench metastable levels to the ground state. In this way spectra could be obtained with fluxes of 104 atoms/second. Future prospects for trapping radioactive atoms in a magneto-optic trap will be discussed.

Electronic Resource