Transition on the entropic elasticity of DNA induced by intercalating molecules

We use optical tweezers to perform stretching experiments on DNA molecules when interacting with the drugs daunomycin and ethidium bromide, which intercalate the DNA molecule. These experiments are performed in the low-force regime from zero up to 2 pN. Our results show that the persistence length of the DNA-drug complexes increases strongly as the drug concentration increases up to some critical value. Above this critical value, the persistence length decreases abruptly and remains practically constant for larger drug concentrations. The contour length of the molecules increases monotonically and saturates as drugs concentration increases. Measured in- tercalants critical concentrations for the persistence length transition coincide with reported values for the helix-coil transition of DNA-drug complexes, obtained from sedimentation experiments.Comment: This experimental article shows and discuss a transition observed in the persistence length of DNA molecules when studied as a function of some intercalating drug concentrations, like daunomycin and ethidium bromide. It has 15 pages and 4 figures. The article presented here is in preprint forma

Upper bound for the conductivity of nanotube networks

Films composed of nanotube networks have their conductivities regulated by the junction resistances formed between tubes. Conductivity values are enhanced by lower junction resistances but should reach a maximum that is limited by the network morphology. By considering ideal ballistic-like contacts between nanotubes we use the Kubo formalism to calculate the upper bound for the conductivity of such films and show how it depends on the nanotube concentration as well as on their aspect ratio. Highest measured conductivities reported so far are approaching this limiting value, suggesting that further progress lies with nanowires other than nanotubes.Comment: 3 pages, 1 figure. Minor changes. Accepted for publication in Applied Physics Letter

Lifestyles and surveillance of sexual and reproductive women’s health

Abstract: Background: The epidemic increase of diseases is closely related to lifestyle changes. The low adhesion to breast self-examination and cervical cytology hinders prevention and early diagnosis during the asymptomatic state of two silent diseases, with nonspecific symptoms that are a major cause of death by cancer in the Portuguese female population. Objectives: To analyze the influence of sociodemographic variables and lifestyles in the surveillance of sexual and reproductive health of Portuguese women. Methods: Quantitative, non-experimental, correlational and cross-sectional study, conducted with a non-probabilistic convenience sample of 522 women aged between 18 and 67 years old, who applied the questionnaires about Breast self-examination, Knowledge about cervical cancer and the Inventory "My Lifestyle" (Ribeiro, 1993. Results: The average age of women is 38.89 years old. Women aged 31-37 years old (28.6%), Portuguese (99.1%), cohabiting with a partner and / or child (74.0%), with an active employment status (67 5%), residing in urban areas (55.8%) with higher education and attending family planning consultations have better lifestyles, without statistical significance (F = 0.016, p = 0.899). Conclusions: Healthy behaviors and lifestyles are crucial to good overall health. Adhesion to surveillance of sexual and reproductive women’s health is influenced by several factors, including the place of residence, employment status and lifestyles. These variables must be considered by health professionals when planning periodic screenings.info:eu-repo/semantics/publishedVersio

Time collection and storage conditions of lipid profile

The stability of samples is crucial for getting reliable concentrations of many analytes, including lipid profile. Thus, the goal of this study was to analyze lipid profile under different storage and temperature conditions. This was a prospective study with 809 patients of both genders. Total cholesterol, triglycerides, high-density lipoprotein cholesterol, low density lipoprotein cholesterol and non-high-density lipoprotein were measured within 1 h from collection at room temperature, after 2-3 h of refrigeration (8 degrees C) and after 4-5 h at room temperature. The processing time and storage conditions did not affect the analytes measured. These findings are important for multicenter studies, because of the difficulties related to centrifugation and freezing of samples immediately after collection.Univ Santo Amaro, Pos Grad Ciencias Saude, Sao Paulo, SP, BrazilUniv Fed Sao Paulo, Setor Lipides Aterosclerose & Biol Vasc Disciplin, Sao Paulo, SP, BrazilUniv Fed Sao Paulo, Disciplina Med Lab, Lab Cent, Sao Paulo, SP, BrazilHosp Israelita Albert Einstein, Med Diagnost Ambulatorial, Sao Paulo, SP, BrazilUniv Fed Sao Paulo, Setor Lipides Aterosclerose & Biol Vasc Disciplin, Sao Paulo, SP, BrazilUniv Fed Sao Paulo, Disciplina Med Lab, Lab Cent, Sao Paulo, SP, BrazilWeb of Scienc

Universal data warehouse management system research proposal

The author proposes research on the creation of a Data Warehouse Management System (involving all its domains: logical and conceptual data model and language, user interface, software and hardware) that is more flexible than current alternatives in adapting to changes in business requirements, while still improving value to the user.info:eu-repo/semantics/publishedVersio

Cosmic String Wakes in Scalar-Tensor Gravities

The formation and evolution of cosmic string wakes in the framework of a scalar-tensor gravity are investigated in this work. We consider a simple model in which cold dark matter flows past an ordinary string and we treat this motion in the Zel'dovich approximation. We make a comaprison between our results and previous results obtained in the context of General Relativity. We propose a mechanism in which the contribution of the scalar field to the evolution of the wakes may lead to a cosmological observation.Comment: Replaced version to be published in the Classical and Quantum Gravit

A reaction-diffusion model for the growth of avascular tumor

A nutrient-limited model for avascular cancer growth including cell proliferation, motility and death is presented. The model qualitatively reproduces commonly observed morphologies for primary tumors, and the simulated patterns are characterized by its gyration radius, total number of cancer cells, and number of cells on tumor periphery. These very distinct morphological patterns follow Gompertz growth curves, but exhibit different scaling laws for their surfaces. Also, the simulated tumors incorporate a spatial structure composed of a central necrotic core, an inner rim of quiescent cells and a narrow outer shell of proliferating cells in agreement with biological data. Finally, our results indicate that the competition for nutrients among normal and cancer cells may be a determinant factor in generating papillary tumor morphology.Comment: 9 pages, 6 figures, to appear in PR

CFD code comparison for 2D airfoil flows

The current paper presents the effort, in the EU AVATAR project, to establish the necessary requirements to obtain consistent lift over drag ratios among seven CFD codes. The flow around a 2D airfoil case is studied, for both transitional and fully turbulent conditions at Reynolds numbers of 3 × 106 and 15 × 106. The necessary grid resolution, domain size, and iterative convergence criteria to have consistent results are discussed, and suggestions are given for best practice. For the fully turbulent results four out of seven codes provide consistent results. For the laminar-turbulent transitional results only three out of seven provided results, and the agreement is generally lower than for the fully turbulent case

The AMBRE Project: searching for the closest solar siblings

Finding solar siblings, that is, stars that formed in the same cluster as the Sun, will yield information about the conditions at the Sun's birthplace. We search for solar sibling candidates in AMBRE, the very large spectra database of solar vicinity stars. Since the ages and chemical abundances of solar siblings are very similar to those of the Sun, we carried out a chemistry- and age-based search for solar sibling candidates. We used high-resolution spectra to derive precise stellar parameters and chemical abundances of the stars. We used these spectroscopic parameters together with Gaia DR2 astrometric data to derive stellar isochronal ages. Gaia data were also used to study the kinematics of the sibling candidates. From the about 17000 stars that are characterized within the AMBRE project, we first selected 55 stars whose metallicities are closest to the solar value (-0.1 < [Fe/H] < 0.1 dex). For these stars we derived precise chemical abundances of several iron-peak, alpha- and neutron-capture elements, based on which we selected 12 solar sibling candidates with average abundances and metallicities between -0.03 to 0.03 dex. Our further selection left us with 4 candidates with stellar ages that are compatible with the solar age within observational uncertainties. For the 2 of the hottest candidates, we derived the carbon isotopic ratios, which are compatible with the solar value. HD186302 is the most precisely characterized and probably the most probable candidate of our 4 best candidates. Very precise chemical characterization and age estimation is necessary to identify solar siblings. We propose that in addition to typical chemical tagging, the study of isotopic ratios can give further important information about the relation of sibling candidates with the Sun. Ideally, asteroseismic age determinations of the candidates could solve the problem of imprecise isochronal ages.Comment: Accepted for publication in A&

Simulation of pre-breakdown discharges in high-pressure air: II. Effect of surface protrusions

Analysis of deviations from the similarity law, observed at high and very high pressures in experiments on discharge ignition and breakdown in corona-like configurations, can serve as a useful, albeit inevitably indirect, source of information about microprotrusions on the surface of the electrodes. In this work, such analysis was performed by means of 2D numerical modelling. Conical or cylindrical protrusions on the surface of the inner electrode were studied and the kinetic scheme includes the electrons, one species of positive ions, and negative ions O− 2 , O−, and O− 3 . It is shown that the deviations from the similarity law, observed in the experiment, may indeed be attributed to enhanced ionization of air molecules in regions of amplified electric field near the microprotrusions. A qualitative agreement with the experiment in all the cases is achieved for protrusion heights of the order of 50 µm. Such values may appear rather high, however there is no other explanation in sight at present. The enhancement of the field electron emission from the surface of the negative electrode due to the amplification of the electric field on the microprotrusion was estimated and found insignificant in the range of values of the protrusion aspect ratio where the enhanced ionization in the gas phase is already appreciable.info:eu-repo/semantics/publishedVersio