Growth rate of the mounds of Nasutitermes sp. (Isoptera: Termitidae)

The growth rate of mounds of Nasutitermes sp. was evaluated by taking monthly measurements of the diameter and the height of ten mounds during twelve months. Through these data, the monthly volumes were calculated for each of them and, later, a dispersion diagram between the volume of each mound and the number of days from the first observation was obtained. From this diagram, it was observed that during the 335 days of observation, the rate of growth of these mounds was null.

Relativistic quark spin coupling effects in the nucleon electromagnetic form factors

We investigate the effect of different forms of relativistic spin coupling of constituent quarks in the nucleon electromagnetic form factors. The four-dimensional integrations in the two-loop Feynman diagram are reduced to the null-plane, such that the light-front wave function is introduced in the computation of the form factors. The neutron charge form factor is very sensitive to different choices of spin coupling schemes, once its magnetic moment is fitted to the experimental value. The scalar coupling between two quarks is preferred by the neutron data, when a reasonable fit of the proton magnetic momentum is found. (C) 2000 Elsevier Science B.V.

Full-color phosphors from amine-functionalized crosslinked hybrids lacking metal activator ions

Sol-gel derived hybrids that contain OCH2CH2 (polyethylene glycol, PEG) repeat units grafted onto a siliceous backbone by urea, -NHC(=O)NH-, or urethane, -NHC(=O)O-, bridges have been prepared. It is demonstrated that the white light PL of these materials results from an unusual convolution of a longer lived emission that originates in the NH groups of the urea/urethane bridges with shorter lived electron-hole recombinations occurring in the nanometer-sized siliceous domains. The PL efficiencies reported here (maximum quantum yields at room temperature of ≈ 0.20 ± 0.02 at a 400 nm excitation wavelength) are in the same range as those for tetramethoxysilane-formic acid, and APTES-acetic acid, sol-gel derived phosphors. The high quantum yields combined with the possibility of tuning the emission to colors across the chromaticity diagram present a wide range of potential applications for these hybrid materials.

Targeting Plasmodium ligands on mosquito salivary glands and midgut with a phage display peptide library

Despite vast efforts and expenditures in the past few decades, malaria continues to kill millions of persons every year, and new approaches for disease control are urgently needed. To complete its life cycle in the mosquito, Plasmodium, the causative agent of malaria, has to traverse the epithelia of the midgut and salivary glands. Although strong circumstantial evidence indicates that parasite interactions with the two organs are specific, hardly any information is available about the interacting molecules. By use of a phage display library, we identified a 12-aa peptide-salivary gland and midgut peptide 1 (SM1)-that binds to the distal lobes of the salivary gland and to the luminal side of the midgut epithelium, but not to the midgut surface facing the hemolymph or to ovaries. The coincidence of the tissues with which parasites and the SM1 peptide interact suggested that the parasite and peptide recognize the same surface ligand. In support of this hypothesis, the SM1 peptide strongly inhibited Plasmodium invasion of salivary gland and midgut epithelia. These experiments suggest a new strategy for the genetic manipulation of mosquito vectorial capacity.

Exploring neutrino mixing with low energy superbeams

We explore the features of neutrino oscillation which are relevant for measurements of the leptonic CP violating phase δ and the sign of Delta;m13 2 in experiments with low-energy conventional superbeams. Toward the goal, we introduce a new powerful tool called the CP trajectory diagram in bi-probability space which allows us to represent pictorially the three effects, the effects of (a) genuine CP violation due to the sin δ term, (6) CP conserving cos δ term, and (c) fake CP violation due to earth matter, separately in a single diagram. By using the diagram, we observe that there is a two-fold ambiguity in the determination of S which is related with the sign of Delta;m13 2. Possible ways of resolving the ambiguity are discussed. In particular, we point out that an in situ simultaneous measurement of δ and the sign of Delta;m13 2 can be carried out at distances of about 700 km, or at the Phase II of the JHF experiment provided that sin δ ·Delta;m13 2 < 0, both with a megaton class water Cherenkov detector.

CERN to Gran Sasso; an ideal distance for superbeam?

We use the CP trajectory diagram as a tool for pictorial representation of the genuine CP and the matter effects to explore the possibility of an in situ simultaneous measurement of δ and the sign of Δℳ13 2. We end up with a low-energy conventional superbeam experiment with a megaton-class water Cherenkov detector and baseline length of about 700 km. A picturesque description of the combined ambiguity which may arise in simultaneous determination of θ13 and the above two quantities is given in terms of CP trajectory diagram.

Microemulsões: Estrutura e aplicações como sistema de liberação de fármacos

Depending on formula composition, microemulsions may be used as a vehicle for drug administration. In this work the main applicable parameters used in the development of pharmaceutical microemulsions (ME) are analyzed. The conceptual description of the system, theoretical parameters related to formation of internal phases and some aspects of ME stability are described. The pseudo ternary phase diagram is used to characterize ME boundaries and to describe different structures in several regions of the diagram. Some applications of ME as drug delivery systems for different administration routes are also analyzed. ME offer advantages as drug delivery systems, because they favor drug absorption, being in most cases faster and more efficient than other methods in delivering the same amount of drug.