Solution space structure of random constraint satisfaction problems with growing domains

In this paper we study the solution space structure of model RB, a standard prototype of Constraint Satisfaction Problem (CSPs) with growing domains. Using rigorous the first and the second moment method, we show that in the solvable phase close to the satisfiability transition, solutions are clustered into exponential number of well-separated clusters, with each cluster contains sub-exponential number of solutions. As a consequence, the system has a clustering (dynamical) transition but no condensation transition. This picture of phase diagram is different from other classic random CSPs with fixed domain size, such as random K-Satisfiability (K-SAT) and graph coloring problems, where condensation transition exists and is distinct from satisfiability transition. Our result verifies the non-rigorous results obtained using cavity method from spin glass theory, and sheds light on the structures of solution spaces of problems with a large number of states.Comment: 8 pages, 1 figure

Molecular, Antigenic, and Functional Characteristics of Ferric Enterobactin Receptor CfrA in Campylobacter jejuni ▿

The ferric enterobactin receptor CfrA not only is responsible for high-affinity iron acquisition in Campylobacter jejuni but also is essential for C. jejuni colonization in animal intestines. In this study, we determined the feasibility of targeting the iron-regulated outer membrane protein CfrA for immune protection against Campylobacter colonization. Alignment of complete CfrA sequences from 15 Campylobacter isolates showed that the levels of amino acid identity for CfrA range from 89% to 98%. Immunoblotting analysis using CfrA-specific antibodies demonstrated that CfrA was dramatically induced under iron-restricted conditions and was widespread and produced in 32 Campylobacter primary strains from various sources and from geographically diverse areas. The immunoblotting survey results were highly correlated with the results of an enterobactin growth promotion assay and a PCR analysis using cfrA-specific primers. Inactivation of the cfrA gene also impaired norepinephrine-mediated growth promotion, suggesting that CfrA is required for C. jejuni to sense intestinal stress hormones during colonization. Complementation of the cfrA mutant with a wild-type cfrA allele in trans fully restored the production and function of CfrA. A growth assay using purified anti-CfrA immunoglobulin G demonstrated that specific CfrA antibodies could block the function of CfrA, which diminished ferric enterobactin-mediated growth promotion under iron-restricted conditions. The inhibitory effect of CfrA antibodies was dose dependent. Immunoblotting analysis also indicated that CfrA was expressed and immunogenic in chickens experimentally infected with C. jejuni. Amino acid substitution mutagenesis demonstrated that R327, a basic amino acid that is highly conserved in CfrA, plays a critical role in ferric enterobactin acquisition in C. jejuni. Together, these findings strongly suggest that CfrA is a promising vaccine candidate for preventing and controlling Campylobacter infection in humans and animal reservoirs

Pesando riscos e benefícios: lições aprendidas com as intervenções terapêuticas de um caso com pré-eclâmpsia grave

JUSTIFICATIVA E OBJETIVO: A pré-eclâmpsia é uma síndrome da disfunção de múltiplos órgãos (SDMO) devido a suas manifestações típicas e atípicas que incluem hipertensão, proteinúria, síndrome HELLP, encefalopatia hipertensiva e coagulopatia. O manejo ideal desses pacientes requer uma avaliação do balanço entre os benefícios e riscos das estratégias terapêuticas, anestésicas e obstétricas. RELATO DE CASO: Paciente grávida de 35 anos, com uma gravidez anterior sem complicações, deu entrada em nosso instituto médico em caráter de emergência às 29 semanas de gravidez. A paciente apresentava-se com tontura, angústia no peito, palpitação, visão embaçada e sangramento vaginal. Após exame físico e laboratorial, a paciente foi diagnosticada com pré-eclâmpsia grave, síndrome HELLP, descolamento prematuro da placenta e SDMO. A paciente também apresentava deformidade da coluna vertebral e pélvica, fixação da articulação mandibular e deslocamento traqueal por causa de um acidente de trânsito ocorrido havia 11 anos. Portanto, uma cesariana de urgência foi feita sob anestesia geral com intubação nasotraqueal usando fio-guia. A paciente recebeu alta diretamente da unidade de terapia intensiva obstétrica no sétimo dia pós-operatório, com pressão arterial normal e recuperação completa das funções orgânicas. CONCLUSÕES: Este caso merece uma discussão mais detalhada sobre as considerações anestésicas no momento de se tomar uma decisão clínica para o tratamento de tal paciente. O bloqueio do neuroeixo é a primeira escolha para pacientes com pré-eclâmpsia submetidas à cesariana quando existe uma trombocitopenia moderada, mas não progressiva. Quando se opta pela anestesia geral, sedação e analgesia adequadas são necessárias para o bom controle da resposta do estresse à intubação, especialmente em pacientes com sinais neurológicos, e para evitar complicações cerebrais sérias

Balancing the Benefits and Risks: Lessons Learned from the Therapeutic Interventions of a Case with Severe Preeclampsia

Background and objective: Preeclampsia is a multiple organ dysfunction syndrome (MODS) for its typical and atypical manifestations including hypertension, proteinuria, HELLP syndrome, hypertensive encephalopathy and coagulopathy. Optimal management for such patients is determined from an assessment of the balance between benefits and risks of anesthetic and obstetric therapeutic strategies. Case Report: A 35-year-old pregnant woman, with one past uncomplicated pregnancy presented at 29 weeks to our medical institute as an emergency with dizziness, chest distress, palpitation, blurred vision and vaginal bleeding. After physical examination and laboratory tests, the patient was diagnosed with severe preeclampsia, HELLP syndrome, placental abruption, and MODS. The patient also presented spinal and pelvic deformity, fixation of articulus mandibularis, and tracheal displacement because of a traffic accident 11 years ago. Therefore, urgent cesarean section was performed under general anesthesia with nasal tracheal intubation using a guide wire. The patient was discharged directly home from the obstetric intensive care unit on the 7th postoperative day with normal blood pressure and full recovery of organic function. Conclusions: This case merits further discussion on the anesthesia considerations concerning how to make a clinical decision when treating such a patient. Neuraxial block is the first choice for preeclampsia patients undergoing cesarean section when a moderate but not progressive thrombocytopenia exists. When general anesthesia is decided, adequate sedation and analgesia is needed to better control the stress response to intubation especially in patients with neurological signs, and to prevent major cerebral complications. Keywords: Pre-Eclampsia, HELLP Syndrome, Multiple Organ Failure, Anesthesia, Obstetrical, Cesarean Sectio

Validation of Reference Genes for Real-Time Quantitative PCR (qPCR) Analysis of Avibacterium paragallinarum.

Real-time quantitative reverse transcription PCR (qRT-PCR) offers a robust method for measurement of gene expression levels. Selection of reliable reference gene(s) for gene expression study is conducive to reduce variations derived from different amounts of RNA and cDNA, the efficiency of the reverse transcriptase or polymerase enzymes. Until now reference genes identified for other members of the family Pasteurellaceae have not been validated for Avibacterium paragallinarum. The aim of this study was to validate nine reference genes of serovars A, B, and C strains of A. paragallinarum in different growth phase by qRT-PCR. Three of the most widely used statistical algorithms, geNorm, NormFinder and ΔCT method were used to evaluate the expression stability of reference genes. Data analyzed by overall rankings showed that in exponential and stationary phase of serovar A, the most stable reference genes were gyrA and atpD respectively; in exponential and stationary phase of serovar B, the most stable reference genes were atpD and recN respectively; in exponential and stationary phase of serovar C, the most stable reference genes were rpoB and recN respectively. This study provides recommendations for stable endogenous control genes for use in further studies involving measurement of gene expression levels

Living Chain-Walking (Co)Polymerization of Propylene and 1-Decene by Nickel α-Diimine Catalysts

Homo- and copolymers of propylene and 1-decene were synthesized by controlled chain-walking (co)polymerization using phenyl substituted α-diimine nickel complexes activated with modified methylaluminoxane (MMAO). This catalytic system was found to polymerize propylene in a living fashion to furnish high molecular weight ethylene-propylene (EP) copolymers. The copolymerizations proceeded to give high molecular weight P/1-decene copolymers with narrow molecular weight distribution (Mw/Mn ≈ 1.2), which indicated a living nature of copolymerization at room temperature. The random copolymerization results indicated the possibility of precise branched structure control, depending on the polymerization temperature and time

Effect of Stress-Induced Grain Growth During Room Temperature Tensile Deformation on Ductility in Nanocrystalline Metals

In the present study defect-free nanocrystalline (nc) Ni-Co alloys with the Co content ranging from 2.4-59.3% (wt.%) were prepared by pulse electrodeposition. X-ray diffraction analysis shows that only a single face-centred cubic solid solution is formed for each alloy and that the grain size reduces monotonically with increasing Co content, which is consistent with transmission electron microscopy (TEM) observations. In the nc Ni-Co alloys, both the ultimate tensile strength and the elongation to failure increase as the Co content increases. The TEM observations reveal that stress-induced grain growth during tensile deformation is significantly suppressed for the nc Ni-Co alloys rich in Co in sharp contrast to those poor in Co. We believe that sufficient solutes could effectively pin grain boundaries making grain boundary motions (e.g. grain boundary migration and/or grain rotation) during deformation more difficult. Thus, stress-induced grain growth is greatly suppressed. At the same time, shear banding plasticity instability is correspondingly delayed leading to the enhanced ductility

Volume mediano efetivo de cristaloides na prevenção de hipotensão arterial em pacientes submetidas à cesariana com raquianestesia

JUSTIFICATIVA E OBJETIVOS: A hipotensão materna associada à raquianestesia no parto cesáreo é a complicação mais frequente e problemática, com sérios riscos para a mãe e comprometimento do bem-estar neonatal. Nesse contexto, o volume efetivo de cristaloides por via intravenosa como uma estratégia de prevensão ainda não foi estimado. MÉTODOS: Oitenta e cinco parturientes com estado físico ASA I/II submetidas à cesariana seletiva foram selecionadas e 67 mulheres elegíveis foram designadas para receber uma pré-carga de cristaloides com 2 mL de bupivacaína hiperbárica a 0,5% (10 mg) mais 50 µg de morfina. O volume de cristaloides foi determinado por um método sequencial up-and-down. Os cristaloides foram infundidos a uma taxa de 100 a 150 mL.min-1 antes da anestesia espinal. O volume inicial de cristaloides foi de 5 mL.kg-1. Os dados do efeito do volume foram ajustados para o modelo sigmoidal de máxima eficácia e a mediana do volume efetivo (VE50) e seu intervalo de confiança (IC) de 95% foram calculados usando a estimativa de máxima verossimilhança e a regressão logística de Firth corrigida. RESULTADOS: Sessenta e sete parturientes completaram o estudo e foram analisadas. Vinte e oito pacientes (41,8%) desenvolveram hipotensão, com queda da pressão arterial sistólica (PAS) superior a 20% do valor basal. O VE50 de cristaloides foi de 12,6 mL.kg-1 (IC 95%, 11,6 a 14,8 mL.kg-1). Com a correção de Firth, a probabilidade conjunta do volume efetivo de cristaloides a 13 mL.kg-1 foi de 50,2% (IC 95%, 30,0% a 83,1%). CONCLUSÕES: O VE50 estimado da pré-carga de cristaloides necessário para prevenir a hipotensão induzida por anestesia espinhal em parto cesáreo é de 13 mL.kg-1 (valor aproximado). Porém, a profilaxia ou terapia com vasoconstritores também deve ser preparada e administrada no momento oportuno