267 research outputs found
Some Integrable Systems in Nonlinear Quantum Optics
In the paper we investigate the theory of quantum optical systems.
As an application we integrate and describe the quantum optical systems which
are generically related to the classical orthogonal polynomials. The family of
coherent states related to these systems is constructed and described. Some
applications are also presented.Comment: 27 page
Influence of quenched dilution on the quasi-long-range ordered phase of the 2d XY model
The influence of non magnetic impurities in the 2d XY model is investigated
through Monte Carlo (MC) simulations. The general picture of the transition is
fully understood from the Harris criterion which predicts that the universality
class is unchanged, and the Berezinskii-Kosterlitz-Thouless description of the
topological transition remains valid. We nevertheless address here the question
about the influence of dilution on the quasi-long-range order at low
temperatures. In particular, we study the asymptotic of the pair correlation
function and report the MC estimates for the critical exponent at
different dilutions. In the weak dilution region, our MC calculations are
further supported by simple spin-wave-like calculations.Comment: 8 pages, 7 eps figure
Testing for heteroskedasticity of the residuals in fuzzy rule-based models
International audienceIn this paper, we propose a new diagnostic checking tool for fuzzy rule-based modelling of time series. Through the study of the residuals in the Lagrange Multiplier testing framework we devise a hypothesis test which allows us to determine if the residual time series is homoscedastic or not, that is, if it has the same variance throughout time. This is another important step towards a statistically sound modelling strategy for fuzzy rule-based models
Avaliação da combinação de aditivos para aumentar a eficiência do processo de sacarificação enzimática da biomassa lignocelulósica
A conversão dos carboidratos complexos presentes na biomassa lignocelulósica em açúcares simples para a obtenção de biocombustíveis e bioprodutos, tais como o etanol de segunda geração (2G), via hidrólise enzimática, ainda apresenta alguns desafios tecnológicos a serem superados de modo a viabilizar economicamente o processo. Dentre esses desafios, destacam-se o baixo rendimento da etapa de sacarificação e o alto custo das enzimas celulolíticas. Uma das formas de mitigar esses fatores negativos consiste no uso de aditivos capazes de reduzir o efeito da adsorção improdutiva de celulases na lignina, aumentando a conversão e reduzindo a perda de enzimas no processo. No entanto, de modo a viabilizar economicamente esta abordagem, o uso de aditivos de baixo custo e/ou em baixas concentrações se faz necessário. Assim, neste projeto de pesquisa foram realizados experimentos para avaliar o efeito da combinação de aditivos no aumento da eficiência da sacarificação enzimática de biomassa lignocelulósica. Para isso, as seguintes etapas foram realizadas: (1) Avaliou-se diferentes processos de extração da proteína de soja a partir do grão de soja moído (farinha crua). O derivado proteico obtido em cada processo foi utilizado como aditivo durante a hidrólise enzimática do bagaço de cana-de-açúcar hidrotérmico e os resultados obtidos foram comparados com os da proteína de soja isolada comercial. Assim, concluiu-se que a fração de proteína extraída com NaOH (3,5% m/v) apresentou o melhor efeito no aumento da liberação de glicose, com ganhos próximos a 60%; (2) Verificou-se o efeito dos surfactantes Tween 80, Tween 20 e Triton X-100 na hidrólise do bagaço de cana. Os três aditivos apresentaram resultados muito similares, optando-se então pelo Tween 80 para as etapas subsequentes do estudo; (3) Associou-se os aditivos Tween 80 e a proteína de soja extraída com NaOH (3,5%) para a realização de um planejamento experimental estatístico de modo a avaliar as concentrações de aditivos que proporcionam o melhor efeito durante a hidrólise (maior aumento na liberação de glicose em relação ao controle sem aditivo). Embora quando avaliados individualmente os aditivos aumentaram a eficiência do processo, nos experimentos combinados o surfactante se mostrou estatisticamente muito mais significativo em comparação com a proteína de soja, mascarando seu resultado; (4) Adicionalmente, separou-se a proteína de soja em frações tais como a glicinina, ?-conglicinina e proteínas ?whey? e avaliou-se o seu efeito na hidrólise enzimática. Em ambos os processos extrativos avaliados, a proteína glicinina conseguiu aumentar a sacarificação enzimática em mais de 40% em relação ao controle. Sendo assim, até o presente momento, foi possível obter uma combinação de aditivos capaz de aumentar a liberação de açúcares simples durante a hidrólise enzimática do bagaço de cana pré-tratado hidrotermicamente em até 80%, contribuindo, assim, para a viabilidade da produção do etanol 2G e bioprodutos
Cyclin-Dependent Kinase Inhibitor p21 Controls Adult Neural Stem Cell Expansion by Regulating Sox2 Gene Expression
In the adult brain, continual neurogenesis of olfactory neurons is sustained by the existence of neural stem cells (NSCs) in the subependymal niche. Elimination of the cyclin-dependent kinase inhibitor 1A (p21) leads to premature exhaustion of the subependymal NSC pool, suggesting a relationship between cell cycle control and long-term self-renewal, but the molecular mechanisms underlying NSC maintenance by p21 remain unexplored. Here we identify a function of p21 in the direct regulation of the expression of pluripotency factor Sox2, a key regulator of the specification and maintenance of neural progenitors. We observe that p21 directly binds a Sox2 enhancer and negatively regulates Sox2 expression in NSCs. Augmented levels of Sox2 in p21 null cells induce replicative stress and a DNA damage response that leads to cell growth arrest mediated by increased levels of p19(Arf) and p53. Our results show a regulation of NSC expansion driven by a p21/Sox2/p53 axis
IL-17 induces an expanded range of downstream genes in reconstituted human epidermis model
Background: IL-17 is the defining cytokine of the Th17, Tc17, and γδ T cell populations that plays a critical role in mediating inflammation and autoimmunity. Psoriasis vulgaris is an inflammatory skin disease mediated by Th1 and Th17 cytokines with relevant contributions of IFN-γ, TNF-α, and IL-17. Despite the pivotal role IL-17 plays in psoriasis, and in contrast to the other key mediators involved in the psoriasis cytokine cascade that are capable of inducing broad effects on keratinocytes, IL-17 was demonstrated to regulate the expression of a limited number of genes in monolayer keratinocytes cultured in vitro. Methodology/Principal Findings: Given the clinical efficacy of anti-IL-17 agents is associated with an impressive reduction in a large set of inflammatory genes, we sought a full-thickness skin model that more closely resemble in vivo epidermal architecture. Using a reconstructed human epidermis (RHE), IL-17 was able to upregulate 419 gene probes and downregulate 216 gene probes. As possible explanation for the increased gene induction in the RHE model is that C/CAATenhancer- binding proteins (C/EBP) -β, the transcription factor regulating IL-17-responsive genes, is expressed preferentially in differentiated keratinocytes. Conclusions/Significance: The genes identified in IL-17-treated RHE are likely relevant to the IL-17 effects in psoriasis, since ixekizumab (anti-IL-17A agent) strongly suppressed the «RHE» genes in psoriasis patients treated in vivo with this IL-17 antagonist. © 2014 Chiricozzi et al
Novel Peptide Sequence (“IQ-tag”) with High Affinity for NIR Fluorochromes Allows Protein and Cell Specific Labeling for In Vivo Imaging
Probes that allow site-specific protein labeling have become critical tools for visualizing biological processes.Here we used phage display to identify a novel peptide sequence with nanomolar affinity for near infrared (NIR) (benz)indolium fluorochromes. The developed peptide sequence ("IQ-tag") allows detection of NIR dyes in a wide range of assays including ELISA, flow cytometry, high throughput screens, microscopy, and optical in vivo imaging.The described method is expected to have broad utility in numerous applications, namely site-specific protein imaging, target identification, cell tracking, and drug development
Intensity noise of injection-locked lasers: Quantum theory using a linearized input-output method
We derive analytical expressions for the quantum-noise spectra of an atomic laser using a linearized input-output method. We generalize the method to the problem of injection-locked lasers. We identify three distinct spectral noise regimes in the solution, unifying previous results. The approach offers insights into the physical processes and is especially suited for comparison with experiment. The quantum spectral noise properties of the pump laser and the injected laser appear explicitly in the solution
Toxoplasmosis in Transplant Recipients, Europe, 2010-2014
Transplantation activity is increasing, leading to a growing number of patients at risk for toxoplasmosis. We reviewed toxoplasmosis prevention practices, prevalence, and outcomes for hematopoietic stem cell transplant (HSCT) and solid organ transplant (SOT; heart, kidney, or liver) patients in Europe. We collected electronic data on the transplant population and prevention guidelines/regulations and clinical data on toxoplasmosis cases diagnosed during 2010-2014. Serologic pretransplant screening of allo-hematopoietic stem cell donors was performed in 80% of countries, screening of organ donors in 100%. SOT recipients were systematically screened in 6 countries. Targeted anti-Toxoplasma chemoprophylaxis was heterogeneous. A total of 87 toxoplasmosis cases were recorded (58 allo-HSCTs, 29 SOTs). The 6-month survival rate was lower among Toxoplasma-seropositive recipients and among allo-hematopoietic stem cell and liver recipients. Chemoprophylaxis improved outcomes for SOT recipients. Toxoplasmosis remains associated with high mortality rates among transplant recipients. Guidelines are urgently needed to standardize prophylactic regimens and optimize patient management
- …