Fluctuating Dimension in a Discrete Model for Quantum Gravity Based on the Spectral Principle

The spectral principle of Connes and Chamseddine is used as a starting point to define a discrete model for Euclidean quantum gravity. Instead of summing over ordinary geometries, we consider the sum over generalized geometries where topology, metric and dimension can fluctuate. The model describes the geometry of spaces with a countable number $n$ of points, and is related to the Gaussian unitary ensemble of Hermitian matrices. We show that this simple model has two phases. The expectation value $$, the average number of points in the universe, is finite in one phase and diverges in the other. We compute the critical point as well as the critical exponent of$$. Moreover, the space-time dimension $\delta$ is a dynamical observable in our model, and plays the role of an order parameter. The computation of $$ is discussed and an upper bound is found, $< 2$.Comment: 10 pages, no figures. Third version: This new version emphasizes the spectral principle rather than the spectral action. Title has been changed accordingly. We also reformulated the computation of the dimension, and added a new reference. To appear in Physical Review Letter

EFEITO DOS S 3LIDOS DISSOLVIDOS DA MADEIRA NA BRANQUEABILIDADE E NAS PROPRIEDADES F\ucdSICO-MEC\uc2NICAS E 3PTICAS DE POLPA kraft BRANQUEADA DE EUCALIPTO

Muitos estudos demonstram que o rendimento da polpa\ue7\ue3o kraft pode ser melhorado pela readsor\ue7\ue3o de xilanas \ue0 polpa durante o cozimento, e o licor negro kraft cont\ue9m fra\ue7\ue3o significativa das xilanas da madeira, sendo uma importante fonte dessas macromol\ue9culas. Por\ue9m, o efeito dessa t\ue9cnica nas propriedades f\uedsicomec\ue2nicas e \uf3pticas de polpa branqueada de eucalipto, ainda n\ue3o est\ue1 bem esclarecido. Neste estudo foram produzidas polpas de eucalipto provenientes de cozimento kraft convencional, com diferentes adi\ue7\uf5es de licor negro (0, 25, 50, 75 e 100 % v/v). Os cozimentos foram conduzidos at\ue9 n\ufamero kappa 17-18 e as polpas resultantes foram deslignificadas com oxig\ueanio em condi\ue7\uf5es fixas. O branqueamento foi realizado utilizando uma sequ\ueancia DHT(EP)DP at\ue9 alvura final 92 % ISO. Em seguida as polpas foram refinadas num moinho PFI a diferentes n\uedveis de revolu\ue7\uf5es (0, 500, 1.500, 3.000 e 6.000) e realizados testes de resist\ueancia ao rasgo, ao arrebentamento e \ue0 passagem de ar, alongamento, opacidade, densidade, volume espec\uedfico aparente, capilaridade Klemm e \uedndice de reten\ue7\ue3o de \ue1gua (WRV). A efici\ueancia e o ganho de alvura da pr\ue9-deslignifica\ue7\ue3o com oxig\ueanio foram ligeiramente prejudicados pela adi\ue7\ue3o de licor negro ao cozimento kraft. A adi\ue7\ue3o de 50 % de licor negro aos cozimentos resultou em polpas de pior branqueabilidade, sendo a demanda de cloro ativo aumentada em 5,3 kg/t celulose seca para obten\ue7\ue3o de alvura 92 % ISO. As propriedades f\uedsico-mec\ue2nicas e \uf3pticas das polpas kraft branqueadas n\ue3o foram influenciadas, significativamente, pelo uso de licor negro no cozimento.Many studies have shown that the yield of kraft pulping can be improved by xylan reabsorption to the pulp during the cooking, and kraft black liquor contains significant fraction of xylan from wood, an important source of these macromolecules. However, the effect of this technique in the physical-mechanical and optical properties of bleached eucalyptus pulp is not very clear. This study produced pulp from eucalyptus kraft conventional cooking with different additions of black liquor (0, 25, 50, 75 and 100% v/v). The cooking was conducted to kappa number 17-18 and the resulting pulps were delignified with oxygen in fixed conditions. Bleaching was performed using a sequence DHT (EP) DP to end whiteness 92% ISO. Next pulps were refined in a PFI mill at different levels of revolutions (0, 500, 1,500, 3,000 and 6,000) and tests of tear resistance, bursting and the air flow, elongation, opacity, density, apparent specific volume, Klemm capillary and water retention value (WRV). The efficiency and brightness gain of the pre-delignification were slightly affected by the addition of black liquor in kraft pulping. The addition of 50% of black liquor to cooking resulted in a worse pulp ability for bleaching, and the chlorine demand increased by 5.3 kg/t pulp oven dry to obtain 92% ISO brightness. The physical-mechanical and optical properties bleached kraft pulps were not influenced significantly by the use of black liquor in cooking

Tuberculosis among HIV-1-infected subjects in a tertiary out-patient service in São Paulo city, Brazil

Atualmente, a tuberculose (TB) é considerada a doença infecciosa mais importante entre os pacientes infectados pelo HIV-1 nos países em desenvolvimento, como o Brasil. Análise retrospectiva dos casos de tuberculose ocorridos a partir de janeiro 1995 até dezembro de 2010 foi realizada em nossa coorte de 599 pacientes HIV positivos. O desfecho primário foi a ocorrência de TB ativa, e 41 casos da doença foram diagnosticados durante este período de 16 anos. As contagens médias do nadir de células T CD4 e ao momento do diagnóstico de TB foram de 146 e 217 células/mm³, respectivamente. A carga viral média de HIV foi de 5,19 log10 cópias/mL, e 59% dos pacientes estavam em tratamento com ART. A incidência de TB foi de 1,47 casos por 100 pessoas-ano, para um tempo total de seguimento da coorte de 2775 pessoas-ano. A probabilidade de sobreviver até 10 anos após o diagnóstico foi de 75% para pacientes com TB, em oposição a 96% para pacientes com outras doenças oportunistas não-TB (p = 0,03). A tuberculose pode ser considerada problema de saúde pública entre as pessoas que vivem com HIV no Brasil, apesar da ampla utilização de anti-retrovirais para o tratamento da infecção pelo HIV / AIDS.TB is currently considered to be the most important infectious disease among HIV-1-infected subjects in developing countries, such as Brazil. A retrospective analysis of TB cases was performed, occurring from January 1995 to December 2010 in our cohort of 599 HIV positive patients. The primary outcome was the occurrence of active TB. Forty-one TB cases were diagnosed over this period of 16 years, among 599 HIV positive patients in an open cohort setting in the city of Sao Paulo, Brazil. All-time lowest mean CD4 T cell count at the time of TB diagnosis was 146 and 186 cells/mm³, respectively. The mean HIV viral load was 5.19 log10 copies/mL, and 59% of the patients were on HAART. TB incidence was 1.47 per 100 person-years, for a total follow-up time of 2775 person-years. The probability of surviving up to 10 years after diagnosis was 75% for TB patients as opposed to 96% for patients with other, non-TB opportunistic diseases (p = 0.03). TB can be considered a public health problem among people living with HIV in Brazil despite of the widespread use of antiretrovirals for the treatment of HIV infection/AIDS

Low bone mineral density among HIV-infected patients in Brazil

Decrease in bone mineral density (BMD) has been a complication among people living with HIV/AIDS. To investigate the prevalence of osteopenia/osteoporosis among HIV-infected people living in São Paulo city, we studied 108 HIV-infected patients (79 men and 29 women). We extracted data from patients’ medical records and BMD was measured by dual-energy X-ray absorptiometry (DXA). Median age of participants was 42 years (interquartile range [IQR] 36-48 years), and the median time since HIV diagnosis was 4.01 years (IQR 2-11 years). Patients had acquired HIV primarily by the sexual route (men who have sex with men 44%, heterosexual 49%). Median age, duration of HIV infection, duration of ART and CD4 nadir were similar for men and women. Plasma viral load was undetectable for 53 patients (49%). Median CD4 T cell count was 399 cells/µL (IQR 247 - 568). Twenty five patients (23%) had LBMD, and there was no statistically significant difference between men and women

Design and validation of an innovative 3D printer containing a co-rotating twin screw extrusion unit

This paper presents the design and validation of an innovative 3D printer containing a co-rotating twin screw extrusion unit (Co-TSE). Single screw print heads were developed in the mid-2000s as an alternative to filament-based 3D printers, but they have limited process flexibility and mixing capacity. The new design accepts material in powder or micro-pellet form, and its dispersive and distributive mixing capacity can be fine tuned by setting output and screw rotation speed independently. The design combines a miniaturized modular Co-TSE operated under starve-fed conditions with a benchtop Cartesian platform. Numerical calculations were performed to ascertain whether the appropriate thermomechanical environment for polymer processing could be created by the proposed design. A prototype was built and extrusion tests were performed under different operating conditions, using polypropylene and a 90/10 wt% polypropylene/polystyrene blend. Two screw configurations were used, with and without kneading discs, to assess the response of the extrusion unit in terms of flow characteristics and mixing performance. The restriction to flow created by the mixing elements determines the starting melt position, and the average residence times, while their shearing and extensional action enhances homogenization effectiveness. The screw configuration and rotation speed do not affect the output, which depends only on the feed rate. Preliminary deposition tests were conducted to determine the feasible printing parameters. A standard tensile test specimen, a square scaffold and a multicolored rectangular box were successfully printed, validating the innovative design. The mechanical properties of printed test specimens were within the expected values.This work was supported by the National Council for Scientific and Technological Development (CNPq), grants 2016-4/442109 and 142348/2018-0, and by the Coordination for the Improvement of Higher Education Personnel (CAPES), finance code 001

Caracterização química e avaliação das atividades antibacteriana, antifúngica, antimicobacteriana e citotóxica de Talinum paniculatum

In this study, the bioactivity of Talinum paniculatum was evaluated, a plant widely used in folk medicine. The extract from the T. paniculatum leaves (LE) was obtained by percolation with ethanol-water and then subjecting it to liquid-liquid partitions, yielding hexane (HX), ethyl acetate (EtOAc), butanol (BuOH), and aqueous (Aq) fractions. Screening for antimicrobial activity of the LE and its fractions was evaluated in vitro through broth microdilution method, against thirteen pathogenic and non-pathogenic microorganisms, and the antimycobacterial activity was performed through agar diffusion assay. The cytotoxic concentrations (CC90) for LE, HX, and EtOAc were obtained on BHK-21 cells by using MTT reduction assay. The LE showed activity against Serratia marcescens and Staphylococcus aureus, with Minimum Inhibitory Concentration (MIC) values of 250 and 500 µg/mL, respectively. Furthermore, HX demonstrated outstanding activity against Micrococcus luteus and Candida albicans with a MIC of 31.2 µg/mL in both cases. The MIC for EtOAc also was 31.2 µg/mL against Escherichia coli. Conversely, BuOH and Aq were inactive against all tested microorganisms and LE proved inactive against Mycobacterium tuberculosisand Mycobacterium bovisas well. Campesterol, stigmasterol, and sitosterol were the proposed structures as main compounds present in the EF and HX/EtOAc fractions, evidenced by mass spectrometry. Therefore, LE, HX, and EtOAc from T. paniculatumshowed potential as possible sources of antimicrobial compounds, mainly HX, for presenting low toxicity on BHK-21 cells with excellent Selectivity Index (SI = CC90/MIC) of 17.72 against C. albicans.Neste estudo foi avaliada a bioatividade de Talinum paniculatum, planta amplamente utilizada na medicina popular. O extrato das folhas (EF) de T. paniculatum foi obtido por percolação com etanol-água e, em seguida, submetido à partição líquido-líquido, obtendo-se as frações hexânica (HX), acetato-etílica (AcOEt), butanólica (BuOH) e aquosa (Aq). A triagem para a atividade antimicrobiana do EF e de suas frações foram avaliadas in vitro através do método de microdiluição em caldo contra treze micro-organismos patogênicos e não-patogênicos e, a atividade antimicobacteriana, foi avaliada através do teste de difusão em ágar. As concentrações citotóxicas (CC90) do EF e das frações HX e AcOEt foram obtidas sobre células da linhagem BHK-21 através do ensaio de redução do MTT. O EF mostrou atividade contra Serratia marcescens e Staphylococcus aureus, com valores de concentração inibitória mínima (CIM) de 250 e 500 µg/mL, respectivamente. Além disso, HX demonstrou excelente atividade contra Micrococcus luteus e Candida albicans com uma CIM de 31,2 µg/mL, em ambos os casos. Contra Escherichia coli, a CIM para AcOEt foi também de 31,2 µg/mL. Por outro lado, as frações BuOH e Aq foram inativas contra todos os micro-organismos testados, assim como o EF contra Mycobacterium tuberculosis e Mycobacterium bovis. Campesterol, estigmasterol e sitosterol foram as estruturas propostas como principais compostos presentes no EF e nas frações HX e AcOEt, evidenciadas através de espectrometria de massas. Portanto, o extrato da folha e as frações HX e AcOEt provenientes de T. paniculatum apresentaram potencial como possíveis fontes de compostos antimicrobianos, HX principalmente, por ter apresentado uma baixa toxicidade sobre células BHK-21 com um bom índice de seletividade (IS = CC90/MIC) de 17,72 contra C. albicans

Chironomidae (Insecta: Diptera) no Estado do Rio de Janeiro, Brasil: Situação Atual, Lista de Espécies e Novos Registros

The species of the family Chironomidae (Insecta: Diptera) recorded to Rio de Janeiro State, southeastern Brazil, are listed, including taxonomic information, geographic distribution and references. Thirty-six species have been recorded in the state. The list was compiled after bibliographic research, faunistic check-lists and catalogs. All references with the original descriptions were investigated, as well as further descriptions and taxonomic changes.As espécies da família Chironomidae (Insecta: Diptera) registradas para o Estado do Rio de Janeiro, região Sudeste do Brasil, são listadas, incluindo informações taxonômicas, distribuição geográfica e referências bibliográficas. Trinta e seis espécies foram registradas até o presente momento para o Estado. A lista foi feita a partir de consultas à bibliografia, catálogos e listas. Foram avaliadas todas as referências com as descrições, além de descrições e mudanças taxonômicas posteriores

Efeito do sexo e da gestação sobre os níveis séricos de frutosamina de indivíduos normais

A frutosamina é um índice do controle metabólico no diabete mélito, refletindo as variações da glicemia nas últimas 2-3 semanas. Representa um conjunto de proteínas glicosadas, cuja fração principal é a albumina. Com o objetivo de es tabelecer os valotes normais da frutosamina em homens, mulheres e gestantes, os níveis séricos de frutosamina forilm medidos em 42 indivíduos normais (homens, n=21, idades 24-81 anos; mulheres, n=21, idades 22-71 anos) e 36 gestantes (idades 18-38 anos, idade gestacional 17-37 semanas). A frutosamina foi medida pelo método colorimétTico em um analisador automático COBAS MIRA-ROCHE. Os valores de frutosamina (média ± desvio padrão) observados em homens (2,99 ± 0.32 mmoljl) foram maiores do que nas mulheres (2,70 ± 0.26 mmol/1). Os valores nom1ais nas gestantes foram menores (2.40 ± 0.22 mmoljl) do que nas mulheres não-grávidas e a correção di! frutosamina de acordo com os túveis de albumina sérica não modificaram os resultados. Os dados apresentados indicam que devem ser considemdos o sexo ea presença ou não de gravidez pam se definir os limites normais dos valores de frutosamina sérica.Serum fructosamine is an index of metabolic control in diabetes mellitus, reflecting the glucose variations during the last 2-3 weeks. It represents a group of glycated proteins, in which the main fraction is albumin. The aim of this study was to determine the normal values in men, women and pregnants. Serum fructosamine was measured in 42healthy subjects (men n=21, aged 24-81 years; women n=21, aged 22-71years) and 36 normal pregnants (aged 18-38 years; gestacional age 17-37weeks). The fructosamine was determined by colorimetric method in an auto-analyser COBAS MIRA-ROCHE. The normal values (mean ± standard deviation) observed in men (2,99 ± 0,32 mmol/L)was higher than women (2,70 ± 0.26 mmol/L). The normal values in pregnants (2.40 ± 0.22mmol/L) were lower than non-pregnant women and the values were not dependent on serum albumin concentration. This data indicated the sex and pregnancy should be taken in account in order to establish the normal range of serum fructosamine