Characterization of an 241AmBe neutron irradiation facility by different spectrometric techniques

An automated panoramic irradiator with a 3 Ci 241Am-Be neutron source is installed in a bunker-type large room at the Universidad Politécnica de Madrid (UPM). It was recently modified and a neutron spectrometry campaign was organized to characterize the neutron fields in different measurement points along the irradiation bench. Four research groups working with different Bonner Sphere Spectrometers (BSS) and using different spectral unfolding codes took part to this exercise. INFN-LNF used a BSS formed by 9 spheres plus bare detector, with cylindrical, almost point like, 6LiI(Eu) scintillator (4 mm x 4 mm, from Ludlum); UAZ-UPM employed a similar system but with only 6 spheres plus bare detector; UAB worked with a 3He filled proportional counter at 8kPa filling pressure, cylindrical 9 mm x 10 mm (05NH1 from Eurisys) with 11 spheres configuration; and CIEMAT used 12 spheres with an spherical 3He SP9 counter (Centronic Ltd., UK) with very high sensitivity due to the large diameter (3.2 cm) and the filling pressure of the order of 228 kPa. Each group applied a different spectral unfolding method: INFN and UAB worked with FRUIT ver. 3.0 with their own response matrixes; UAZ-UPM used the BUNKIUT unfolding code with the response matrix UTA4 and CIEMAT employed the GRAVEL-MAXED-IQU package with their own response matrix. The paper shows the main results obtained in terms of neutron spectra at fixed distances from the source as well as total neutron fluence rate and ambient dose equivalent rate H*(10) determined from the spectra. The latter are compared with the readings of a common active survey-meter (LB 6411). The small differences in the results of the various groups are discussed.

Experimental results on multicarrier SIMO HF communications

Achieving reliable communication over HF channels is known to be challenging due to the particularly hostile propagation medium. To address this problem, diversity techniques were shown to be promising. In this paper, we demonstrate through experimental results the benefits of different diversity strategies when applied to multi-input-multi-output (MIMO) multicarrier systems. The performance gains of polarisation, space and frequency diversities are quantified using different measurement campaigns.

A IMPORTÂNCIA DO CONHECIMENTO TÁCITO NA FORMAÇÃO DO EDUCADOR

Esta dissertação tem por objetivo evidenciar a importância do conhecimento tácito na formação do educador. Para tanto, pretendemos primeiramente conceituar os principais fundamentos do conhecimento tácito desenvolvidos por Michael Polanyi durante o século XX. Num segundo momento, realizaremos uma aproximação entre o conhecimento tácito e o campo educacional, tendo como objetivos a procura pela descoberta e pela percepção humana, pontos considerados por Polanyi como essenciais para a constituição de nosso conhecimento tácito. Aprofundando-se na dimensão educacional, analisaremos, em especial, os docentes no campo da literatura. De cunho bibliográfico, esta dissertação toma como base de referência os estudos de Polanyi, bem como outros teóricos da educação e da teoria literária, como Cláudio Saiani e Antonio Candido.(AU)

A IMPORTÂNCIA DO CONHECIMENTO TÁCITO NA FORMAÇÃO DO EDUCADOR

Esta dissertação tem por objetivo evidenciar a importância do conhecimento tácito na formação do educador. Para tanto, pretendemos primeiramente conceituar os principais fundamentos do conhecimento tácito desenvolvidos por Michael Polanyi durante o século XX. Num segundo momento, realizaremos uma aproximação entre o conhecimento tácito e o campo educacional, tendo como objetivos a procura pela descoberta e pela percepção humana, pontos considerados por Polanyi como essenciais para a constituição de nosso conhecimento tácito. Aprofundando-se na dimensão educacional, analisaremos, em especial, os docentes no campo da literatura. De cunho bibliográfico, esta dissertação toma como base de referência os estudos de Polanyi, bem como outros teóricos da educação e da teoria literária, como Cláudio Saiani e Antonio Candido.(AU)

HLA-G expression in melanoma: A way for tumor cells to escape from immunosurveillance

Considering the well established role of nonclassical HLA-G class I molecules in inhibiting natural killer (NK) cell function, the consequence of abnormal HLA-G expression in malignant cells should be the escape of tumors from immunosurveillance. To examine this hypothesis, we analyzed HLA-G expression and NK sensitivity in human malignant melanoma cells. Our analysis of three melanoma cell lines and ex vivo biopsy demonstrated that (i) IGR and M74 human melanoma cell lines exhibit a high level of HLA-G transcription with differential HLA-G isoform transcription and protein expression patterns, (ii) a higher level of HLA-G transcription ex vivo is detected in a skin melanoma metastasis biopsy compared with a healthy skin fragment from the same individual, and (iii) HLA-G protein isoforms other than membrane-bound HLA-G1 protect IGR from NK lysis. It thus appears of critical importance to consider the specific role of HLA-G expression in tumors in the design of future cancer immunotherapies.

Overexpression of DNA polymerase β in cell results in a mutator phenotype and a decreased sensitivity to anticancer drugs

DNA polymerase β (pol β) is the most error prone of all known eukaryotic DNA polymerases tested in vitro. Here, we show that cells overexpressing pol β cDNA have acquired a spontaneous mutator phenotype. By measuring the appearance of mutational events using three independent assays, we found that genetic instability increased in the cell lines that overexpressed pol β. In addition, these cells displayed a decreased sensitivity to cancer chemotherapeutic, bifunctional, DNA-damaging agents such as cisplatin, melphalan, and mechlorethamine, resulting in enhanced mutagenesis compared with control cells. By using cell-free extracts and modified DNA substrates, we present data in support of error-prone translesion replication as one of the key determinants of tolerance phenotype. These results have implications for the potential role of pol β overexpression in cancer predisposition and tumor progression during chemotherapy.

Mechanism-based inhibition of the melatonin rhythm enzyme: Pharmacologic exploitation of active site functional plasticity

Serotonin N-acetyltransferase is the enzyme responsible for the diurnal rhythm of melatonin production in the pineal gland of animals and humans. Inhibitors of this enzyme active in cell culture have not been reported previously. The compound N-bromoacetyltryptamine was shown to be a potent inhibitor of this enzyme in vitro and in a pineal cell culture assay (IC50 ≈ 500 nM). The mechanism of inhibition is suggested to involve a serotonin N-acetyltransferase-catalyzed alkylation reaction between N-bromoacetyltryptamine and reduced CoA, resulting in the production of a tight-binding bisubstrate analog inhibitor. This alkyltransferase activity is apparently catalyzed at a functionally distinct site compared with the acetyltransferase activity active site on serotonin N-acetyltransferase. Such active site plasticity is suggested to result from a subtle conformational alteration in the protein. This plasticity allows for an unusual form of mechanism-based inhibition with multiple turnovers, resulting in “molecular fratricide.” N-bromoacetyltryptamine should serve as a useful tool for dissecting the role of melatonin in circadian rhythm as well as a potential lead compound for therapeutic use in mood and sleep disorders.

Definition of the HLA-A29 peptide ligand motif allows prediction of potential T-cell epitopes from the retinal soluble antigen, a candidate autoantigen in birdshot retinopathy.

The peptide-binding motif of HLA-A29, the predisposing allele for birdshot retinopathy, was determined after acid-elution of endogenous peptides from purified HLA-A29 molecules. Individual and pooled HPLC fractions were sequenced by Edman degradation. Major anchor residues could be defined as glutamate at the second position of the peptide and as tyrosine at the carboxyl terminus. In vitro binding of polyglycine synthetic peptides to purified HLA-A29 molecules also revealed the need for an auxiliary anchor residue at the third position, preferably phenylalanine. By using this motif, we synthesized six peptides from the retinal soluble antigen, a candidate autoantigen in autoimmune uveoretinitis. Their in vitro binding was tested on HLA-A29 and also on HLA-B44 and HLA-B61, two alleles sharing close peptide-binding motifs. Two peptides derived from the carboxyl-terminal sequence of the human retinal soluble antigen bound efficiently to HLA-A29. This study could contribute to the prediction of T-cell epitopes from retinal autoantigens implicated in birdshot retinopathy.

Alterações na resposta imune inata e adaptativa induzidas por Escherichia coli enteroinvasora em modelo murino

Durante uma infecção, uma complexa seqüência de eventos é inkiada após a invasão do hospedeiro por microrganismos patogênicos. Escherichia coli enteroinvasora (EIEC), assim como Shigella, causa disenteria através da invasão da mucosa do cólon, levando à destruição tecidual e inflamação. Para que ocorra um processo infeccioso, porém, são necessários inóculos de 102 Shigella e 106 EIEC. Foram avaliados aspectos da resposta inflamatória desencadeada pela infecção por EIEC em modelo murino, comparativamente a Shigella. A infecção de macrófagos J774 por EIEC resultou em fagocitose bacteriana, comprometimento da viabilidade do macrófago e produção de citocinas. Macrófagos de camundongos C57BU6 infectados com EIEC produziram NO, que parece ser importante no controle da infecção. Foi observado que camundongos INOS nocaute apresentaram maior produção de citocinas pró-inflamatórias e maior letalidade após infecção do que os selvagens. EIEC induziu a migração de granulócitos e monócitos para o peritônio, e a secreção de citocinas por estas células. Houve proliferação de linfócitos em resposta aos antígenos solúveis de EIEC, mas não foi detectada produção de citocinas por estes linfócitos.Comparativamente a Shigella, EIEC escapou mais lentamente do macrófago, induziu menor produção de citocinas pró-inflamatórias e NO, e menor ativação dos linfócitos T. Estes dados sugerem o desafio com EIEC desencadeia uma resposta menos severa no hospedeiro do que Shigella, o que explicaria a forma mais branda de disenteria e resolução mais rápida do processo infeccioso causado por EIEC.

Wavefront-Guided Laser Treatment Using a High-Resolution Aberrometer to Measure Irregular Corneas: A Pilot Study

PURPOSE: To evaluate in a pilot study the visual, refractive, corneal topographic, and aberrometric changes after wavefront-guided LASIK or photorefractive keratectomy (PRK) using a high-resolution aberrometer to calculate the treatment for aberrated eyes. METHODS: Twenty aberrated eyes of 18 patients undergoing wavefront-guided LASIK or PRK using the VISX STARS4IR excimer laser and the iDesign aberrometer (Abbott Medical Optics, Inc., Santa Ana, CA) were enrolled in this prospective study. Three groups were differentiated: keratoconus post-CXL group including 11 keratoconic eyes (10 patients), post-LASIK group including 5 eyes (5 patients) with previous decentered LASIK treatments, and post-RK group including 4 eyes (3 patients) with previous radial keratotomy. Visual, refractive, contrast sensitivity, corneal topographic, and ocular aberrometric changes were evaluated during a 6-month follow-up. RESULTS: An improvement in uncorrected (UDVA) and corrected visual acuity (CDVA) associated with a reduction in the spherical equivalent was observed in the three groups, but was only statistically significant in the keratoconus post-CXL and post-LASIK groups (P ≤ .04). All eyes gained one or more lines of CDVA after surgery. Improvements in contrast sensitivity were observed in the three groups, but they were only statistically significant in the keratoconus post-CXL and post-LASIK groups (P ≤ .04). Regarding aberrations, a reduction was observed in trefoil aberrations in the keratoconus post-CXL group (P = .05) and significant reductions in higher-order and primary coma aberrations in the post-LASIK group (P = .04). CONCLUSIONS: Wavefront-guided laser enhancements using the evaluated platform seem to be safe and effective to restore the visual function in aberrated eyes.

Standardization, certification, maintenance, and dissemination of large scale engineering software systems : a panel discussion held as a part of the Second National Symposium on Computerized Structural Analysis and Design /

Includes bibliographical references

[Précis de jurisprudence musulmane ou principes de législation musulmane civile et religieuse selon le rite malékite /

Contiene: Vol. I - Vol. II - Vol. III - Vol. IV - Vol. V - Vol. VI.