Properties of minimally doubled fermions

Most quark actions in lattice QCD encounter difficulties with chiral sym-rnmetry and its spontaneous breakdown. Minimally doubled fermions (MDF)rnare a category of strictly local chiral lattice fermions, whose continuum limitrnreproduces two degenerate quark flavours. The two poles of their Dirac ope-rnrator are aligned such that symmetries under charge conjugation or reflectionrnof one particular direction are explictly broken at finite lattice spacing. Pro-rnperties of MDF are scrutinised with regard to broken symmetry and mesonrnspectrum to discern their suitability for numerical studies of QCD.rnrnInteractions induce anisotropic operator mixing for MDF. Hence, resto-rnration of broken symmetries in the continuum limit requires three coun-rnterterms, one of which is power-law divergent. Counterterms and operatorrnmixing are studied perturbatively for two variants of MDF. Two indepen-rndent non-perturbative procedures for removal of the power-law divergencernare developed by means of a numerical study of hadronic observables forrnone variant of MDF in quenched approximation. Though three out of fourrnpseudoscalar mesons are affected by lattice artefacts, the spectrum’s conti-rnnuum limit is consistent with two-flavour QCD. Thus, suitability of MDF forrnnumerical studies of QCD in the quenched approximation is demonstrated.

From doubled Chern–Simons–Maxwell lattice gauge theory to extensions of the toric code

We regularize compact and non-compact Abelian Chern–Simons–Maxwell theories on a spatial lattice using the Hamiltonian formulation. We consider a doubled theory with gauge fields living on a lattice and its dual lattice. The Hilbert space of the theory is a product of local Hilbert spaces, each associated with a link and the corresponding dual link. The two electric field operators associated with the link-pair do not commute. In the non-compact case with gauge group R, each local Hilbert space is analogous to the one of a charged “particle” moving in the link-pair group space R2 in a constant “magnetic” background field. In the compact case, the link-pair group space is a torus U(1)2 threaded by k units of quantized “magnetic” flux, with k being the level of the Chern–Simons theory. The holonomies of the torus U(1)2 give rise to two self-adjoint extension parameters, which form two non-dynamical background lattice gauge fields that explicitly break the manifest gauge symmetry from U(1) to Z(k). The local Hilbert space of a link-pair then decomposes into representations of a magnetic translation group. In the pure Chern–Simons limit of a large “photon” mass, this results in a Z(k)-symmetric variant of Kitaev’s toric code, self-adjointly extended by the two non-dynamical background lattice gauge fields. Electric charges on the original lattice and on the dual lattice obey mutually anyonic statistics with the statistics angle . Non-Abelian U(k) Berry gauge fields that arise from the self-adjoint extension parameters may be interesting in the context of quantum information processing.

Effect of colchicine and amiprophos-methyl on the production of in vitro doubled haploid onion plants and correlation assessment between ploidy level and stomatal size

Doubled haploid onion (Allium cepa L.) plants allow the production of completely homozygous lines for a later production of hybrids. The haploid plants are normally produced using in vitro gynogenesis. The obtained haploid plantlets must be treated with different agents for doubling chromosomes. It is necessary to adjust the concentration and the length of treatment of the doubling agent. In this case, the effect of 250 and 500 mg.L-1 colchicine and 15.2; 30 and 60 mg.L- 1 amiprophos-methyl during 24 and 48 h was assessed over the rate of onion haploid plantlets chromosome doubling. The best duplication treatment was 250 mg.L-1 colchicine for 48 h, which yielded 100% of doubled haploid plants. On the other hand, a positive correlation resulted from the ploidy level and stomatal size, and a negative correlation between the level of ploidy and stomatal density. Significant differences between the stomatal length, width and density in haploid and doubled haploid plantlets were observed. An economical and quick method to test ploidy level in onion plantlets is proposed through the measurement of stomatal size and density.

Risks of a growing balance of payments deficit : hearing before the Subcommittee on Economic Policy of the Committee on Banking, Housing, and Urban Affairs, United States Senate, One Hundred Seventh Congress, first session on the burgeoning balance of payments deficit which nearly doubled in the last few years, from $300 million in 1999 to an expected $500 billion in 2001, July 25, 2001.

"Printed for the use of the Committee on Banking, Housing, and Urban Affairs."

1.2-μm semiconductor disk laser frequency doubled with periodically poled lithium tantalate crystal

In this letter, we demonstrate an optically pumped semiconductor disk laser frequency doubled with a periodically poled lithium tantalate crystal. Crystals with various lengths were tested for intracavity frequency conversion. The semiconductor disk laser exploited GaInNAs-based active region with GaAsAlAs distributed Bragg mirror to produce emission at 1.2- μm wavelength. The frequency doubled power up to 760 mW at the wavelength of 610 nm was achieved with a 2-mm-long crystal. © 2010 IEEE.

73 nm wavelength tuning from a frequency-doubled quantum-dot laser in PPKTP waveguides

A compact all-room-temperature CW 73-nm tunable laser source in the visible spectral region (574nm-647nm) has been demonstrated by frequency-doubling of a broadly-tunable InAs/GaAs quantum dot external-cavity diode laser in periodically-poled potassium titanyl phosphate waveguides with a maximum output power in excess of 12mW and a maximum conversion efficiency exceeding 10%. Three waveguides with different cross-sectional areas (4×4μm2, 3×5μm2 and 2x6μm2) were investigated. Introduction - Development of compact broadly tunable laser sources in the visible spectral region is currently very attractive area of research with applications ranging from photomedicine and biophotonics to confocal fluorescence microscopy and laser projection displays. In this respect, semiconductor lasers with their small size, high efficiency, reliability and low cost are very promising for realization of such sources by frequency­doubling of the infrared light in nonlinear crystal waveguides. Furthermore, the wide tunability offered by quantum-dot (QD) external-cavity diode lasers (ECDL), due to the temperature insensibility and broad gain bandwidth [1,2], is very promising for the development of tunable visible laser sources [3,4]. In this work we show a compact green-to-red tunable all­room-temperature CW laser source using a frequency-doubled InAs/GaAs QD-ECDL in periodically-poled potassium titanyl phosphate (PPKTP) crystal waveguides. This laser source generates frequency-doubled light over the 574nm-647nm wavelength range utilizing the significant difference in the effective refractive indices of high-order and low-order modes in multimode waveguides [3]. Experimental results - Experimental setup used in this work was similar to that described in [3] and consisted of a QD gain chip in the quasi­Littrow configuration and a PPKTP waveguide. Coarse wavelength tuning of the QD-ECDL between 1140 nm and 1300 nm at 20°C was possible for pump current of 1.5 A. The laser output was coupled into the PPKTP waveguide using an AR-coated 40x aspheric lens (NA ~ 0.55). The PPKTP frequency-doubling crystal (not AR coated) used in our work was 18 mm in length and was periodically poled for SHG (with the poling period of ~ 11.574 11m). The crystal contained 3 different waveguides with cross-sectional areas of ~ 4x4 11m2, 3x5 11m2 and 2x6 11m2. Both the pump laser and the PPKTP crystal were operating at room temperature. The waveguides with cross-sectional areas of 4x411m2, 3x511m2 and 2x611m2 demonstrated the tunability in the wavelength ranges of 577nm - 647nm, 576nm -643nm and 574nm - 641nm, respectively, with a maximum output power of 12.04mW at 606 nm Conclusion - We demonstrated a compact all-room-temperature broadly­tunable laser source operating in the visible spectral region between 574nm and 647nm. This laser source is based on second harmonic generation in PPKTP waveguides with different cross-sectional areas using an InAs/GaAs QD-ECDL References [I] E.U. Rafailov, M.A. Cataluna, and W. Sibbett, Nat. Phot. 1,395 (2007). [2] K.A. Fedorova, M.A. Cataluna, I. Krestnikov, D. Livshits, and E.U. Rafailov, Opt. Express 18(18), 19438-19443 (2010). [3] K.A. Fedorova, G.S. Sokolovskii, P.R. Battle, D.A. Livshits, and E.U. Rafailov, Laser Phys. Lett. 9, 790-795 (2012). [4] K.A. Fedorova,G.S. Sokolovskii, D.T. Nikitichev, P.R. Battle, I.L. Krestnikov, D.A. Livshits, and E.U. Rafailov, Opt. Lett. 38(15), 2835-2837 (2013) © 2014 IEEE.

Quantitative genetic analysis of grain yield in an Australian Brassica napus doubled-haploid population

Epidemiologia da leishmaniose tegumentar americana no Estado do Acre, Amazônia brasileira

Efetuou-se estudo estatístico descritivo em 8.516 casos de leishmaniose tegumentar americana no Estado do Acre, Brasil, no período de 2001 a 2006 (segundo período), comparando-se com os resultados de publicação anterior com dados no mesmo estado entre 1992 e 1997 (primeiro período). A prevalência no estado mais que dobrou entre os dois momentos (55,7/10 mil habitantes de 1992 a 1997 e 128,5/10 mil habitantes entre 2001 e 2006. O sexo masculino foi o mais acometido (68,8%, n = 5.860) no segundo período. A média das idades foi de 26,3 anos, valor discretamente menor do que o do primeiro período. Pacientes com baixa escolaridade foram os mais acometidos pela doença. As demais variáveis avaliadas foram zona de residência, ocupação, critério de diagnóstico, forma clínica, tratamento, recidiva, tempo para procurar tratamento e evolução da doença. Conclui-se que houve piora nos indicadores epidemiológicos da leishmaniose tegumentar americana avaliados no estado entre os períodos estudados.

INTERPOPULATION COMPARISON OF REPRODUCTION OF THE ATLANTIC SHRIMP HIPPOLYTE OBLIQUIMANUS (CARIDEA: HIPPOLYTIDAE)

The genus Hippolyte is represented by typically small shrimps with intriguing mechanisms of reproduction. In order to study possible variability in reproductive aspects among different populations, we conducted an exhaustive comparative study of H. obliquimanus from South (Brazil) and Central American (Costa Rica) waters. The study focuses on fecundity and reproductive output. Mean size of ovigerous females was significantly larger, and both mean reproductive output and mean fecundity were significantly higher in specimens from Costa Rica then in those collected in Brazil. Embryo volume was significantly smaller in the Costa Rican population, and in both populations embryos doubled their volume during embryogenesis. We discuss and compare our findings with the information available regarding H. obliquimanus and other hippolytid shrimp. The reproductive traits of both populations of H. obliquimanus show some important differences which may reflect adaptations to local environmental conditions, demonstrating a high plasticity of reproductive features of the species in Brazilian and Costa Rican waters.

Control of the Intracellular Redox State by Glucose Participates in the Insulin Secretion Mechanism

Background: Production of reactive oxygen species (ROS) due to chronic exposure to glucose has been associated with impaired beta cell function and diabetes. However, physiologically, beta cells are well equipped to deal with episodic glucose loads, to which they respond with a fine tuned glucose-stimulated insulin secretion (GSIS). In the present study, a systematic investigation in rat pancreatic islets about the changes in the redox environment induced by acute exposure to glucose was carried out. Methodology/Principal Findings: Short term incubations were performed in isolated rat pancreatic islets. Glucose dose- and time-dependently reduced the intracellular ROS content in pancreatic islets as assayed by fluorescence in a confocal microscope. This decrease was due to activation of pentose-phosphate pathway (PPP). Inhibition of PPP blunted the redox control as well as GSIS in a dose-dependent manner. The addition of low doses of ROS scavengers at high glucose concentration acutely improved beta cell function. The ROS scavenger N-acetyl-L-cysteine increased the intracellular calcium response to glucose that was associated with a small decrease in ROS content. Additionally, the presence of the hydrogen peroxide-specific scavenger catalase, in its membrane-permeable form, nearly doubled glucose metabolism. Interestingly, though an increase in GSIS was also observed, this did not match the effect on glucose metabolism. Conclusions: The control of ROS content via PPP activation by glucose importantly contributes to the mechanisms that couple the glucose stimulus to insulin secretion. Moreover, we identified intracellular hydrogen peroxide as an inhibitor of glucose metabolism intrinsic to rat pancreatic islets. These findings suggest that the intracellular adjustment of the redox environment by glucose plays an important role in the mechanism of GSIS.

The Amazon Frontier of Land-Use Change: Croplands and Consequences for Greenhouse Gas Emissions

The Brazilian Amazon is one of the most rapidly developing agricultural frontiers in the world. The authors assess changes in cropland area and the intensification of cropping in the Brazilian agricultural frontier state of Mato Grosso using remote sensing and develop a greenhouse gas emissions budget. The most common type of intensification in this region is a shift from single-to double-cropping patterns and associated changes in management, including increased fertilization. Using the enhanced vegetation index (EVI) from the Moderate Resolution Imaging Spectroradiometer (MODIS) sensor, the authors created a green-leaf phenology for 2001-06 that was temporally smoothed with a wavelet filter. The wavelet-smoothed green-leaf phenology was analyzed to detect cropland areas and their cropping patterns. The authors document cropland extensification and double-cropping intensification validated with field data with 85% accuracy for detecting croplands and 64% and 89% accuracy for detecting single-and double-cropping patterns, respectively. The results show that croplands more than doubled from 2001 to 2006 to cover about 100 000 km(2) and that new double-cropping intensification occurred on over 20% of croplands. Variations are seen in the annual rates of extensification and double-cropping intensification. Greenhouse gas emissions are estimated for the period 2001-06 due to conversion of natural vegetation and pastures to row-crop agriculture in Mato Grosso averaged 179 Tg CO(2)-e yr(-1),over half the typical fossil fuel emissions for the country in recent years.