Discrete typing units of Trypanosoma cruzi identified in rural dogs and cats in the humid Argentinean Chaco

The discrete typing units (DTUs) of Trypanosoma cruzi that infect domestic dogs and cats have rarely been studied. With this purpose we conducted a cross-sectional xenodiagnostic survey of dog and cat populations residing in 2 infested rural villages in Pampa del Indio, in the humid Argentine Chaco. Parasites were isolated by culture from 44 dogs and 12 cats with a positive xenodiagnosis. DTUs were identified from parasite culture samples using a strategy based on multiple polymerase-chain reactions. TcVI was identified in 37 of 44 dogs and in 10 of 12 cats, whereas TcV was identified in 5 dogs and in 2 cats -a new finding for cats. No mixed infections were detected. The occurrence of 2 dogs infected with TcIII -classically found in armadillos- suggests a probable link with the local sylvatic transmission cycle involving Dasypus novemcinctus armadillos and a potential risk of human infection with TcIII. Our study reinforces the importance of dogs and cats as domestic reservoir hosts and sources of various DTUs infecting humans, and suggests a link between dogs and the sylvatic transmission cycle of TcIII.Fil: Enriquez, Gustavo Fabián. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ecología, Genética y Evolución; ArgentinaFil: Cardinal, Marta Victoria. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ecología, Genética y Evolución; ArgentinaFil: Orozco, Maria Marcela. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ecología, Genética y Evolución; ArgentinaFil: Lanati, L.. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ecología, Genética y Evolución; ArgentinaFil: Schijman, Alejandro Gabriel. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Investigaciones en Ingeniería Genética y Biología Molecular "Dr. Héctor N. Torres"; ArgentinaFil: Gurtler, Ricardo Esteban. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ecología, Genética y Evolución; Argentin

Chagas Disease and the London Declaration on Neglected Tropical Diseases

Fil: Tarleton, Rick L.. University of Georgia; Estados Unidos. Chagas Disease Foundation; Estados UnidosFil: Gurtler, Ricardo Esteban. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Ecología, Genética y Evolución de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Ecología, Genética y Evolución de Buenos Aires; ArgentinaFil: Urbina, Julio A.. Instituto Venezolano de Investigaciones Científicas; VenezuelaFil: Ramsey, Janine. Instituto Nacional de Salud Pública; MéxicoFil: Viotti, Rodolfo Jorge. Provincia de Buenos Aires. Ministerio de Salud. Hospital Interzonal de Agudos "Eva Perón"; Argentin

Contribuição dos humanos, cães e gatos à transmissão do Trypanosoma cruzi na Região do Chaco Argentino

Foi determinada a prevalência da infecção por T. cruzi nos humanos, cães e gatos, pertencentes a 47 rancherías em três povoados rurais; Guanaco Muerto (Córdoba), La Invernada e Amamás (Santiago del Estero), mediante reações seroldgicas e xenodiagnóstico. Poram examinadas 245 pessoas, 123 cães e 14 gatos. A taxa de prevalência na população foi entre 58,7% (GM) e 49,6% (LI). Foram detectados 76% de cães infectados, o que resultou significativamente superior aos 51% encontrados nos humanos. As porcentagens de cães (64,2%) e gatos (63,6%) com parasitemia foram significativamente superiores à correspondente aos humanos (12,5%). Se bem que 79% dos gatos estavam infectados, sua pequena quantidade e seus hábitos de perambulação determinam que sua participação na transmissão doméstica do T. cruzi seja restrita. Não obstante existir em média um maior número de humanos que de cães em cada lar, tanto de sujeitos sãos como infectados (6,5 vs. 3,3 e 3,4 vs. 2,4, respectivamente), foram detectados também na média mais cães que humanos com parasitemia em cada casa (2,1 vs. 1,0). As altas porcentagens de cães infectados e com parasitemia, além do hábito de repouso intra-domiciliário o qual ocasiona estreito contacto entre eles e os barbeiros determinam que os cães sejam os principais provedores de parásitos à disposição para a transmissão, e os hospedeiros mais importantes para /nanutenção da doença de Chagas na Região do Chaco Argentino.Trypanosoma cruzi prevalence rates of human, dog and cat populations from 47 households of 3 rural localities of the phytogeographical Chaqueña area of Argentina were determined both by serological and xenodiagnostic procedures. Human prevalence rates were uniform and ranged from 49.6 to 58.7%. Overall prevalence rate in dogs (75.0%) was significantly higher than in humans (51.0%). The overall proportion of parasitemic individuals assessed by xenodiagnosis was significantly higher in either dog (64.2%) or cat (63.6%) populations than among humans (12.5%). Although both the average number of resident as well as infected individuals per household was higher for people than for dogs (6.5 vs. 3.3, and 3.4 vs. 2.4, respectively), the reverse was recorded when parasitemic individuals were considered (1.0 vs. 2.1). Results are discussed in relation to dog between dogs and people, and dogs and bugs. In the light of present data, dogs must be considered as the major donors of parasites to vector bugs and thus, principal contributors to transmission in this region of Argentina

No Fossil Disk in the T Tauri Multiple System V773 Tau

We present new multi-epoch near-infrared and optical high-angular images of the V773 Tau pre-main sequence triple system, a weak-line T Tauri (WTTS) system in which the presence of an evolved, ``fossil'' protoplanetary disk has been inferred on the basis of a significant infrared excess. Our images reveal a fourth object bound to the system, V773 Tau D. While it is much fainter than all other components at 2 micron, it is the brightest source in the system at 4.7 micron. We also present medium-resolution K band adaptive optics spectroscopy of this object, which is featureless with the exception of a weak Br gamma emission line. Based on this spectrum and on the spectral energy distribution of the system, we show that V773 Tau D is another member of the small class of ``infrared companions'' (IRCs) to T Tauri stars. It is the least luminous, and probably the least massive, component of the system, as opposed to most other IRCs, which suggests that numerous low-luminosity IRCs such as V773 Tau D may still remain to be discovered. Furthermore, it is the source of the strong IR excess in the system. We therefore reject the interpretation of this excess as the signature of a fossil (or ``passive'') disk and further suggest that these systems may be much less frequent than previously thought. We further show that V773 Tau C is a variable classical T Tauri star (CTTS) and that its motion provides a well constrained orbital model. We show that V773 Tau D can be dynamically stable within this quadruple system if its orbit is highly inclined. Finally, V773 Tau is the first multiple system to display such a variety of evolutionary states (WTTS, CTTS, IRC), which may be the consequence of the strong star-star interactions in this compact quadruple system.Comment: Accepted for publication in Astrophysical Journal, 29 pages, 2 tables, 5 figure

Spin-dependent Bohm trajectories associated with an electronic transition in hydrogen

The Bohm causal theory of quantum mechanics with spin-dependence is used to determine electron trajectories when a hydrogen atom is subjected to (semi-classical) radiation. The transition between the 1s ground state and the 2p0 state is examined. It is found that transitions can be identified along Bohm trajectories. The trajectories lie on invariant hyperboloid surfaces of revolution in R^3. The energy along the trajectories is also discussed in relation to the hydrogen energy eigenvalues.Comment: 18 pages, 8 figure

HIV Genetic Diversity in Cameroon: Possible Public Health Importance

To monitor the evolving molecular epidemiology and genetic diversity of HIV in a country where many distinct strains cocirculate, we performed genetic analyses on sequences from 75 HIV-1-infected Cameroonians: 74 were group M and 1 was group O. Of the group M sequences, 74 were classified into the following env gp41 subtypes or recombinant forms: CRF02 (n = 54), CRF09 (n = 2), CRF13 (n = 2), A (n = 5), CRF11 (n = 4), CRF06 (n = 1), G (n = 2), F2 (n = 2), and E (n = 1, CRF01), and 1 was a JG recombinant. Comparison of phylogenies for 70 matched gp41 and protease sequences showed inconsistent classifications for 18 (26%) strains. Our data show that recombination is rampant in Cameroon with recombinant viruses continuing to recombine, adding to the complexity of circulating HIV strains. This expanding genetic diversity raises public health concerns for the ability of diagnostic assays to detect these unique HIV mosaic variants and for the development of broadly effective HIV vaccines.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/63150/1/aid.2006.22.812.pd

A Census of the Chamaeleon I Star-Forming Region

Optical spectroscopy has been obtained for 179 objects that have been previously identified as possible members of the cluster, that lack either accurate spectral types or clear evidence of membership, and that are optically visible (I<18). I have used these spectroscopic data and all other available constraints to evaluate the spectral classifications and membership status of a total sample of 288 candidate members of Chamaeleon I that have appeared in published studies of the cluster. The latest census of Chamaeleon I now contains 158 members, 8 of which are later than M6 and thus are likely to be brown dwarfs. I find that many of the objects identified as members of Chamaeleon I in recent surveys are actually field stars. Meanwhile, 7 of 9 candidates discovered by Carpenter and coworkers are confirmed as members, one of which is the coolest known member of Chamaeleon I at a spectral type of M8 (~0.03 M_sun). I have estimated extinctions, luminosities, and effective temperatures for the members and used these data to construct an H-R diagram for the cluster. Chamaeleon I has a median age of ~2 Myr according to evolutionary models, and hence is similar in age to IC 348 and is slightly older than Taurus (~1 Myr). The measurement of an IMF for Chamaeleon I from this census is not possible because of the disparate methods with which the known members were originally selected, and must await an unbiased, magnitude-limited survey of the cluster.Comment: 59 pages, 22 figure

A Way to Reopen the Window for Electroweak Baryogenesis

We reanalyse the sphaleron bound of electroweak baryogenesis when allowing deviations to the Friedmann equation. These modifications are well motivated in the context of brane cosmology where they appear without being in conflict with major experimental constraints on four-dimensional gravity. While suppressed at the time of nucleosynthesis, these corrections can dominate at the time of the electroweak phase transition and in certain cases provide the amount of expansion needed to freeze out the baryon asymmetry without requiring a strongly first order phase transition. The sphaleron bound is substantially weakened and can even disappear so that the constraints on the higgs and stop masses do not apply anymore. Such modification of cosmology at early times therefore reopens the parameter space allowing electroweak baryogenesis which had been reduced substantially given the new bound on the higgs mass imposed by LEP. In contrast with previous attempts to turn around the sphaleron bound using alternative cosmologies, we are still considering that the electroweak phase transition takes place in a radiation dominated universe. The universe is expanding fast because of the modification of the Friedmann equation itself without the need for a scalar field and therefore evading the problem of the decay of this scalar field after the completion of the phase transition and the risk that its release of entropy dilutes the baryon asymmetry produced at the transition.Comment: 19 pages, 3 figures; v2: minor changes, remark added at end of section 5 and in caption of figure 1; v3: references added, version to be publishe

Baryogenesis from Primordial Blackholes after Electroweak Phase Transition

Incorporating a realistic model for accretion of ultra-relativistic particles by primordial blackholes (PBHs), we study the evolution of an Einstein-de Sitter universe consisting of PBHs embedded in a thermal bath from the epoch $\sim 10^{-33}$ sec to $\sim 5\times 10^{-9}$ sec. In this paper we use Barrow et al's ansatz to model blackhole evaporation in which the modified Hawking temperature goes to zero in the limit of the blackhole attaining a relic state with mass $\sim m_{pl}$. Both single mass PBH case as well as the case in which blackhole masses are distributed in the range $8\times 10^2 - 3\times 10^5$ gm have been considered in our analysis. Blackholes with mass larger than $\sim 10^5$ gm appear to survive beyond the electroweak phase transition and, therefore, successfully manage to create baryon excess via $X-\bar X$ emissions, averting the baryon number wash-out due to sphalerons. In this scenario, we find that the contribution to the baryon-to-entropy ratio by PBHs of initial mass $m$ is given by $\sim \epsilon \zeta (m/1 {gm})^{-1}$, where $\epsilon$ and $\zeta$ are the CP-violating parameter and the initial mass fraction of the PBHs, respectively. For $\epsilon$ larger than $\sim 10^{-4}$, the observed matter-antimatter asymmetry in the universe can be attributed to the evaporation of PBHs.Comment: Latex2e file with seven figures included as postscript file

Measuring the Broken Phase Sphaleron Rate Nonperturbatively

We present details for a method to compute the broken phase sphaleron rate (rate of hot baryon number violation below the electroweak phase transition) nonperturbatively, using a combination of multicanonical and real time lattice techniques. The calculation includes the ``dynamical prefactor,'' which accounts for prompt recrossings of the sphaleron barrier. The prefactor depends on the hard thermal loops, getting smaller with increasing Debye mass; but for realistic Debye masses the effect is not large. The baryon number erasure rate in the broken phase is slower than a perturbative estimate by about exp(-3.6). Assuming the electroweak phase transition has enough latent heat to reheat the universe to the equilibrium temperature, baryon number is preserved after the phase transition if the ratio of (``dimensionally reduced'' thermal) scalar to gauge couplings (lambda / g^2) is less than .037.Comment: 41 pages, 13 figures included with psfig. Some wordings clarified, nothing substantial change