4,5-bis(benzoylsulfanyl)-1,3-dithiol-2-one

Peer reviewedPublisher PD

Two-component mixture of charged particles confined in a channel: melting

The melting of a binary system of charged particles confined in a {\it quasi}-one-dimensional parabolic channel is studied through Monte Carlo simulations. At zero temperature the particles are ordered in parallel chains. The melting is anisotropic and different melting temperatures are obtained according to the spatial direction, and the different types of particles present in the system. Melting is very different for the single-, two- and four-chain configurations. A temperature induced structural phase transition is found between two different four chain ordered states which is absent in the mono-disperse system. In the mixed regime, where the two types of particles are only slightly different, melting is almost isotropic and a thermally induced homogeneous distribution of the distinct types of charges is observed.Comment: To appear in Journal of Physics: condensed matter ; (13 pages, 12 figures

Trypanosomatids are common and diverse parasites of Drosophila

SUMMARYDrosophila melanogasteris an important model system of immunity and parasite resistance, yet most studies use parasites that do not naturally infect this organism. We have studied trypanosomatids in natural populations to assess the prevalence and diversity of these gut parasites. We collected several species ofDrosophilafrom Europe and surveyed them for trypanosomatids using conserved primers for two genes. We have used the conserved GAPDH sequence to construct a phylogenetic tree and the highly variable spliced leader RNA to assay genetic diversity. All 5 of the species that we examined were infected, and the average prevalence ranged from 1 to 6%. There are several different groups of trypanosomatids, related to other monoxenous Trypanosomatidae. These may represent new trypanosomatid species and were found in different species of EuropeanDrosophilafrom different geographical locations. The detection of a little studied natural pathogen inD. melanogasterand related species provides new opportunities for research into both theDrosophilaimmune response and the evolution of hosts and parasites.</jats:p

Calagem e adubação do algodoeiro no cerrado.

bitstream/CNPA/18296/1/CIRTEC92.pd

A importância do controle de qualidade dos inoculantes.

bitstream/item/71827/1/ID-30961.pd

Ecologia e formas de aproveitamento econômico do cipó-titica (Heteropsis flexuosa (H.B.K.) G. S. Bunting).

Os objetivos deste trabalho foram fazer uma descrição das características ecológicas e das formas de aproveitamento econômicos do cipó-titica (Heteropsis flexuosa (H.B.K.) G. S. Bunting) na Amazônia.bitstream/item/24777/1/doc95-cipotitica.pd

Relationship Between Bioimpedance-Determined Body Composition and Peritoneal Transport in Peritoneal Dialysis

PURPOSE: In peritoneal dialysis (PD) patients, body fluid homeostasis is dependent on peritoneal elimination of water and solutes. Patients with less favorable peritoneal transport parameters should be more overhydrated. Despite this, the association between faster transport and overhydration (OH) is weak, and the factors that influence hydration status are still poorly characterized. Modified peritoneal equilibration tests (PET) offer us new parameters that might correlate better with hydration status, like free water transport (FWT). The aim of this study was thus to establish the relationships between new peritoneal transport parameters and body composition parameters estimated by bioimpedance spectroscopy (BIS). METHODS: Prospective observational study on incident PD patients with a baseline and 1-year follow-up evaluation. RESULTS: 61 patients were included in the baseline evaluation, 19 of whom had a 1-year follow-up evaluation; 67.2% were fluid overloaded. There was a negative correlation between D/P creatinine and FWT (r = -0.598, p = 0.000). The fraction of FWT was negatively correlated with OH (r = -0.302, p = 0.018). Peritoneal protein losses (PPL) were also correlated with OH (r = 0.287, p = 0.028). There were no significant differences in OH according to small-solute transport status or fluid output parameters. After 1 year, we observed a significant worsening of renal function and an improvement in 24-hour ultrafiltration (UF) and hydration status, but we detected no differences in peritoneal transport of water or solutes that could explain these changes. CONCLUSIONS: There is a poor relationship between kidney/peritoneal function parameters and body composition parameters. The fraction of FWT and PPL may be underestimated markers of peritoneal health and of its contribution to the hydration status.info:eu-repo/semantics/publishedVersio

Structural and dynamical properties of a quasi-one-dimensional classical binary system

The ground state configurations and the \lq{}\lq{}normal\rq{}\rq{} mode spectra of a $quasi$-one-dimensional (Q1D) binary system of charged particles interacting through a screened Coulomb potential are presented. The minimum energy configurations were obtained analytically and independently through molecular dynamic simulations. A rich variety of ordered structures were found as a function of the screening parameter, the particle density, and the ratio between the charges of the distinct types of particles. Continuous and discontinuous structural transitions, as well as an unexpected symmetry breaking in the charge distribution are observed when the density of the system is changed. For near equal charges we found a disordered phase where a mixing of the two types of particles occurs. The phonon dispersion curves were calculated within the harmonic approximation for the one- and two-chain structures.Comment: 11 pages, 11 fig

The Genesis of Cosmological Tracker Fields

The role of the quintessence field as a probable candidate for the repulsive dark energy, the conditions for tracking and the requisites for tracker fields are examined. The concept of `integrated tracking' is introduced and a new criterion for the existence of tracker potentials is derived assuming monotonic increase in the scalar energy density parameter \Omega_\phi with the evolution of the universe as suggested by the astrophysical constraints. It provides a technique to investigate generic potentials of the tracker fields. The general properties of the tracker fields are discussed and their behaviour with respect to tracking parameter \epsilon is analyzed. It is shown that the tracker fields around the limiting value \epsilon \simeq \frac 23 give the best fit with the observational constraints.Comment: 8 pages, Latex file, 1 figure, comments adde