Thin-layer agar for detection of resistance to rifampicin, ofloxacin and kanamycin in Mycobacterium tuberculosis isolates

BACKGROUND: In low-income countries there is a great need for economical methods for testing the susceptibility of Mycobacterium tuberculosis to antibiotics. OBJECTIVE: To evaluate the thin-layer agar (TLA) for rapid detection of resistance to rifampicin (RMP), ofloxacin (OFX) and kanamycin (KM) in M. tuberculosis clinical isolates and to determine the sensitivity, specificity and time to positivity compared to the gold standard method. METHODS: One hundred and forty-seven clinical isolates of M. tuberculosis were studied. For the TLA method, a quadrant Petri plate containing 7H11 agar with RMP, OFX and KM was used. Results were compared to the Bactec MGIT960 for RMP and the proportion method for OFX and KM. RESULTS: The sensitivity and specificity for RMP and OFX were 100% and for KM they were 100% and 98.7%, respectively. The use of a TLA quadrant plate enables the rapid detection of resistance to the three anti-tuberculosis drugs RMP, OFX and KM in a median of 10 days. CONCLUSION: TLA was an accurate method for the detection of resistance in the three drugs studied. This faster method is simple to perform, providing an alternative method when more sophisticated techniques are not available in low-resource settings

Neutral heavy lepton production at next high energy e+e−e^+e^- linear colliders

The discovery potential for detecting new heavy Majorana and Dirac neutrinos at some recently proposed high energy $e^+e^-$ colliders is discussed. These new particles are suggested by grand unified theories and superstring-inspired models. For these models the production of a single heavy neutrino is shown to be more relevant than pair production when comparing cross sections and neutrino mass ranges. The process $e^+e^- \longrightarrow {\nu} e^{\pm} W^{\mp}$ is calculated including on-shell and off-shell heavy neutrino effects. We present a detailed study of cross sections and distributions that shows a clear separation between the signal and standard model contributions, even after including hadronization effects.Comment: 4 pages including 15 figures, 1 table. RevTex. Accepted in Physical Review

Experimental Observation of Environment-induced Sudden Death of Entanglement

We demonstrate the difference between local, single-particle dynamics and global dynamics of entangled quantum systems coupled to independent environments. Using an all-optical experimental setup, we show that, while the environment-induced decay of each system is asymptotic, quantum entanglement may suddenly disappear. This "sudden death" constitutes yet another distinct and counter-intuitive trait of entanglement.Comment: 4 pages, 4 figure

Critical Behavior of a Three-State Potts Model on a Voronoi Lattice

We use the single-histogram technique to study the critical behavior of the three-state Potts model on a (random) Voronoi-Delaunay lattice with size ranging from 250 to 8000 sites. We consider the effect of an exponential decay of the interactions with the distance,$J(r)=J_0\exp(-ar)$, with $a>0$, and observe that this system seems to have critical exponents $\gamma$ and $\nu$ which are different from the respective exponents of the three-state Potts model on a regular square lattice. However, the ratio $\gamma/\nu$ remains essentially the same. We find numerical evidences (although not conclusive, due to the small range of system size) that the specific heat on this random system behaves as a power-law for $a=0$ and as a logarithmic divergence for $a=0.5$ and $a=1.0$Comment: 3 pages, 5 figure

Traumatic Neuroma Following Sagittal Split Osteotomy of the Mandible

A 16-year-old male underwent bilateral sagittal split osteotomy of the mandible to correct a mandibular deficiency. Twenty-one years later, a routine panoramic radiograph revealed a radiolucent lesion on the left side of the mandible. The lesion was biopsied. As the patient did not have symptoms and the lesion was connected to the inferior alveolar nerve, the lesion was not totally excised in order to preserve nerve function. The histological features were consistent with traumatic neuroma, and no further surgical procedure was planned

Digital image processing and enhancement of gravity data as an aid to the definition of the structural framework of the north Tucano-Jatobá basins, Northeastern Brazil

Técnicas de processamento digital de imagens foram aplicadas a dados gravimétricos visando melhorar definição das principais feições estruturais na porção norte do Rift Recôncavo-Tucano-Jatobá. Os processamentos utilizados incluíram: (a) conversão de dados Bouguer e residual-Bouguer, no formato de grids, em imagens realçadas; (b) geração de composições falsa cor híbridas e (c) geração de modelos de elevação digital com visão em perspectiva. A análise integrada desse conjunto de dados permitiu reconhecer feições lineares e sutis variações espaciais nos dados gravimétricos, as quais foram associadas a unidades tectónicas no contexto do rift, tais como: plataformas em rampa, baixos e altos estruturais, horsts, grabens e falhas de borda.Digitally processed and enhanced gravity data in raster format were used to improve the definition of the main structural features in the northern part of the Reconcavo-Tucano-Jatoba Rift. Image processing techniques included: (a) conversion of Bouguer and residual-Bouguer gridded data into contrast-enhanced gray-level images; (b) generation of enhanced hybrid pseudo-color composites; and (c) generation of a gravity digital elevation model in perspective views. The integrated analysis of this dataset permitted the recognition of subtle trends and intensity-related spatial variations in gravity data, tentatively related to the following tectonic units of the RTJ Rift: ramp platforms, structural lows and highs, along-length horsts, grabens, faulted borders and extensional faults

Characterization of the Intra-Unit-Cell magnetic order in Bi2Sr2CaCu2O8+d

As in YBa2Cu3O6+x and HgBa2CuO8+d, the pseudo-gap state in Bi2Sr2CaCu2O8+d is characterized by the existence of an intra-unit-cell magnetic order revealed by polarized neutron scattering technique. We report here a supplementary set of polarized neutron scattering measurements for which the direction of the magnetic moment is determined and the magnetic intensity is calibrated in absolute units. The new data allow a close comparison between bilayer systems YBa2Cu3O6+x and Bi2Sr2CaCu2O8+d and rise important questions concerning the range of the magnetic correlations and the role of disorder around optimal doping.Comment: 12 pages, 8 figures, submitted to physical review

Modulation of tomato pericarp firmness through pH and calcium: Implications for the texture of fresh-cut fruit

The effect of pH and calcium on pericarp firmness and pectin solubility was investigated in tomato fruit (Lycopersicon esculentum Mill. ‘Tavira’). Pericarp disks were vacuum-infiltrated with 50mM CaCI₂ or with distilled water and incubated for 4 h in buffer solutions at pH 4.5 and 7.0, and subsequently stored at 2 ◦C for 5 days. CaCl2 treatment had a significant effect on firmness retention in disks from turning and ripe fruit. Pericarp disks from mature-green fruit infiltrated with CaCl2 were firmer than untreated tissue after a 4 h incubation period, but the effect of calcium did not persist during storage at 2 ◦C. pH had a significant effect on the firmness of pericarp disks excised from turning and ripe fruit, but not on mature-green tissue. Treatments at pH 7.0 caused a reduction of the softening rate in disks from turning and ripe fruit, but had no significant effect at the mature-green stage. Water-soluble pectins decreased significantly in mature-green and ripe pericarp tissue following treatment with CaCl2 at pH 7.0, suggesting that pH affects pectin dissolution. Firmness changes induced by pH and calcium after a 4 h incubation treatment were highly correlated with pectin dissolution. The results indicate that, besides calcium, pH contributes to textural changes in tomato fruit pericarp. Since wounding inflicted during processing and acidic solutions used to prevent enzymic browning and microbial growth are likely to acidify the apoplast of fresh-cut fruit, the ability to maintain an apoplastic pH near 7.0 can significantly contribute to enhanced firmness of fresh-cut fruit