A common algebraic description for probabilistic and quantum computations

AbstractThrough the study of gate arrays we develop a unified framework to deal with probabilistic and quantum computations, where the former is shown to be a natural special case of the latter. On this basis we show how to encode a probabilistic or quantum gate array into a sum-free tensor formula which satisfies the conditions of the partial trace problem, and vice-versa; that is, given a tensor formula F of order n×1 over a semiring S plus a positive integer k, deciding whether the kth partial trace of the matrix valSn,n(F·FT) fulfills a certain property. We use this to show that a certain promise version of the sum-free partial trace problem is complete for the class pr- BPP (promise BPP) for formulas over the semiring (Q+,+,·) of the positive rational numbers, for pr-BQP (promise BQP) in the case of formulas defined over the field (Q+,+,·), and if the promise is given up, then completeness for PP is shown, regardless whether tensor formulas over positive rationals or rationals in general are used. This suggests that the difference between probabilistic and quantum polytime computers may ultimately lie in the possibility, in the latter case, of having destructive interference between computations occurring in parallel. Moreover, by considering variants of this problem, classes like ⊕P, NP, C=P, its complement co-C=P, the promise version of Valiant's class UP, its generalization promise SPP, and unique polytime US can be characterized by carrying the problem properties and the underlying semiring

Atividade antifúngica dos óleos essenciais de sassafrás (Ocotea odorifera Vell.) e alecrim (Rosmarinus officinalis L.) sobre o gênero Candida Antifungal activity of Brazilian sassafras (Ocotea odorifera Vell.) and rosemary (Rosmarinus officinalis L.) essential oils against the genus Candida

Este estudo objetivou avaliar, in vitro, a atividade antifúngica dos óleos essenciais de Ocotea odorifera (Vellozo) Rohwer (Sassafrás) e Rosmarinus officinalis L. (Alecrim) sobre cepas de Candida albicans e C. tropicalis, envolvidas com infecções da cavidade oral. Para tanto, 16 cepas de Candida de origem clínica e de referência foram utilizadas para determinação da concentração inibitória mínima (CIM), utilizando a técnica da microdiluição. Miconazol e nistatina foram utilizados como controles positivos. Observou-se discreta atividade antifúngica de ambos os óleos, com CIM de 2,5 mg mL-1 para sassafrás e CIM de 5 mg mL-1 para alecrim em 68% e 81% das cepas avaliadas, respectivamente. Todas as cepas de Candida mostraram-se sensíveis ao miconazol e nistatina. A partir dos resultados obtidos, foi possível concluir que os óleos essenciais de O. odorifera Vell. e R. officinalis L. apresentam fraca atividade sobre cepas de C. albicans e C. tropicalis envolvidas em infecções da cavidade oral.<br>This study aimed to evaluate the in vitro antifungal activity of essential oils from Ocotea odorifera Vell. (Brazilian sassafras) and Rosmarinus officinalis L. (rosemary) against Candida albicans and C. tropicalis strains, both involved in oral cavity infections. Thus, 16 Candida strains from clinical origin and standards were used to determine the minimum inhibitory concentration (MIC), using the microdilution technique. Miconazole and nystatin were used as positive controls. A slight antifungal activity was observed for both oils, with 2.5 mg mL-1 MIC for Brazilian sassafras and 5 mg mL-1 MIC for rosemary in 68 and 81% strains, respectively. All Candida strains were sensitive to miconazole and nystatin. In conclusion, essential oils from O. odorifera Vell. and R. officinalis L. had weak activity against C. albicans and C. tropicalis strains involved in oral cavity infections

Variações interanuais na fenologia de uma comunidade arbórea de floresta semidecídua no sudeste do Brasil Interannual variation in the phenology of a tree community in a semideciduous seasonal forest in southeast Brazil

As comunidades arbóreas de florestas tropicais localizadas em regiões com clima sazonal tendem a ajustar a fenologia da queda de folhas e da produção de flores e frutos à sazonalidade climática. Neste estudo monitoramos a comunidade arbórea de uma floresta semidecidual no período de quatro anos (2001 a 2004), a fim de analisar a relação entre o número de espécies perdendo folhas, florescendo e frutificando e a variação anual do comprimento do dia, precipitação e temperatura durante o período de observação. Além disso, avaliamos se essas três fenofases repetem os mesmos padrões em anos sucessivos. Regressões lineares simples indicaram que o número de espécies perdendo folhas foi negativamente relacionado com as três variáveis ambientais para os quatro anos de estudo, sendo o comprimento do dia e a temperatura os melhores preditores para esta fenofase. Houve também relação significativa do comprimento do dia com o número de espécies florescendo e frutificando nos quatro anos, porém, precipitação e temperatura não foram relacionadas com estas fenofases em todos os anos de estudo. Os testes de estatística circular indicaram forte sazonalidade para queda foliar, com data média durante o mês de julho independente do ano, ao passo que para floração e frutificação não foi detectada sazonalidade significativa. Como resultado, o número de espécies perdendo folhas foi correlacionado entre todos os anos sucessivos. Entretanto, não houve correlação do número de espécies florescendo e frutificando em 2003 e 2004, provavelmente devido às altas temperaturas ocorridas neste último ano. Os resultados deste estudo sugerem que a queda de folhas é uma fenofase altamente previsível temporalmente. Ao contrário, a floração e a frutificação podem variar ano a ano como conseqüência de anomalias climáticas. Essas variações podem ser relevantes para o entendimento dos efeitos em longo prazo de mudanças climáticas sobre as florestas sazonais.<br>Tropical tree communities in regions with seasonal climate usually adjust leaf-fall, flowering and fruiting phenology to climate seasonality. Here we monitored a tree community over a 4-year period in order to assess the relationship between the number of species presenting leaf fall, flower and fruit and annual variation in day length, precipitation and temperature. Moreover, we asked whether the three phenological variables have the same patterns in successive years. Simple regression analyses showed that the number of species shedding leaves was negatively related to the three environmental variables during the four years, with day length and temperature as the best predictors. There was also a relationship between day length and the number of species flowering and fruiting, while rainfall and temperature were only related to these phenophases in some years. The circular statistics indicate highly significant seasonality only for leaf fall, whereas for flowering and fruiting significant seasonal patterns were not detected. The number of species in leaf fall was correlated between all successive years. However, the number of species in flower and fruit was not significantly correlated between 2003 and 2004. Overall, our results suggest that leaf fall is highly predictable over time. On the contrary, flowering and fruiting may present year-to-year variation as a result of climatic anomalies such as the high temperatures detected in 2004. These variations may be relevant to understand the effects of climate change on seasonal forests in long-term studies

Ectopic expression of the Arabidopsis florigen gene FLOWERING LOCUS T

Ectopic expression of specific genes in seeds could be a tool for molecular design of crops to alter seed dormancy and germination, thereby improving production. Here, a seed-specific vector, 12S-pLEELA, was applied to study the roles of genes in Arabidopsis seeds. Transgenic lines containing FLOWERING LOCUS T (FT) driven by the 12S promoter exhibited significantly increased seed dormancy and earlier flowering. Mutated FT(Y85H) and TERMINAL FLOWER1 (TFL1) transgenic lines also showed increased seed dormancy but without altered flowering time. FT(Y85H) and TFL1 caused weaker seed dormancy enhancement compared to FT. The FT and TFL1 transgenic lines showed hypersensitivity to paclobutrazol, but not to abscisic acid in seed germination. The levels of bioactive gibberellin 3 (GA(3)) and GA(4) were significantly reduced, consistent with decreased expression of COPALYL DIPHOSPHATE SYNTHASE (CPS), KAURENE OXIDASE (KO), GIBBERELLIN 3-OXIDASE2 (GA3ox2), and GA20ox1 in p12S::FT lines. Exogenous GA(4+7) could recover the germination ability of FT transgenic lines. These results revealed that FT regulates GA biosynthesis. A genetic analysis indicated that the GA signaling regulator SPINDLY (SPY) is epistatic to FT in GA-mediated seed germination. Furthermore, DELAY OF GERMINATION1 (DOG1) showed significantly higher transcript levels in p12S::FT lines. Seed dormancy analysis of dog1-2 spy-3 p12S::FT-2 indicated that the combination of SPY and DOG1 is epistatic to FT in the regulation of dormancy. Overall, we showed that ectopic expression of FT and TFL1 in seeds enhances dormancy through affecting GA and DOG1 pathways