Elastoplastic and fracture behaviour of semi-crystalline polymers under multiaxial stress states

The deformation behaviour and fracture mechanisms of highdensity polyethylene (HDPE), polypropylene (PP) and polyamide 6 (PA 6) are investigated experimentally under different stress states and at different crosshead speeds of 1, 20 and 200 mm/min. Fracture surface morphologies were investigated in a series of specimens tested at 200 mm/min under combined tension/shear loading at three different loading angles ( ? = 0, 30deg and 90deg) at room temperature (RT) and 50 �C. In addition, the effects of notch profile radii (stress triaxiality) on HDPE, PP and PA 6 fracture behaviour have been studied at RT, using flat and cylindrical notched specimens. Specimens� geometries were carefully designed to achieve various loading conditions and allowing to explore initial stress triaxialities ranged from 0 in pure shear loading ( ? = 0�) to a maximum of 0.84 for flat notched specimens with radius of 5 mm. The yield load shows an explicit dependency on temperature and crosshead speed. The fracture surfaces analysed reveals damage mechanisms such as crazing, void and cavitation formation. Two or more mechanisms are predominant, which means that the stresses along fracture process are not uniform

EFFECTS OF THE REDUCED IMPACT LOGGING ON THE GROWTH PHASES OF A TERRA FIRME FOREST IN THE STATE OF PAR\uc1, BRAZIL

Avaliou-se a influ\ueancia da explora\ue7\ue3o florestal de impacto reduzido nas fases de desenvolvimento de uma floresta de terra firme, submetida a duas intensidades de colheita de madeira na regi\ue3o de Paragominas, PA. Os dados foram coletados em 36 parcelas permanentes de 0,25 ha, distribu\ueddas aleatoriamente entre os tratamentos (T1 - floresta explorada com colheita apenas do fuste comercial das \ue1rvores e T2 - floresta explorada com colheita do fuste e dos res\uedduos lenhosos) e testemunha (T0 - floresta n\ue3o explorada). Foram consideradas tr\ueas fases de desenvolvimento da floresta: madura (DAP > 40 cm); em constru\ue7\ue3o (10 cm < DAP < 40 cm); e clareiras (ocorr\ueancia de uma abertura no dossel e pouca ou nenhuma \ue1rvore com DAP > 10 cm). Para verificar a homogeneidade de vari\ue2ncias das subparcelas entre tratamentos, fases e anos, recorreu-se ao teste de Bonferroni, a partir das estat\uedsticas de Bartlett e Levene. Foi aplicada uma an\ue1lise de vari\ue2ncia para o n\ufamero de subparcelas por fases, anos e tratamentos, ao n\uedvel de signific\ue2ncia de 5%. Foi realizado, tamb\ue9m, o teste Tukey para contrastar as m\ue9dias da intera\ue7\ue3o entre as fases e ano. Antes da explora\ue7\ue3o, a floresta encontrava-se com 57,0% da \ue1rea em est\ue1dio de constru\ue7\ue3o, 38,9% em est\ue1dio de floresta madura e apenas 4,1% em fase de clareira. A explora\ue7\ue3o reduziu a \ue1rea de floresta madura e em constru\ue7\ue3o, ocasionando o aumento do n\ufamero de clareiras, entretanto, esse aumento n\ue3o apresentou diferen\ue7a estat\uedstica. Um ano ap\uf3s a explora\ue7\ue3o foi observado o aumento da \ue1rea de floresta madura (38,4%) e de constru\ue7\ue3o (53,1%) e a redu\ue7\ue3o das \ue1reas de clareiras (8,4%). Tr\ueas anos ap\uf3s a explora\ue7\ue3o os percentuais observados (Floresta madura: 37,1%; Floresta em constru\ue7\ue3o: 57,9%; Clareira: 5,0%), foram semelhantes aos encontrados antes da explora\ue7\ue3o florestal. As fases de desenvolvimento da floresta n\ue3o foram influenciadas pela explora\ue7\ue3o florestal, ao longo do per\uedodo estudado, independente do tratamento empregado. A floresta em estudo demonstrou capacidade de se regenerar, proporcionando o fechamento do dossel, apesar do curto espa\ue7o de tempo.The influence of reduced impact logging were evaluated on the growth phases of a terra firme forest in the Paragominas region, state of Par\ue1, that was logged considering two intensities of timber harvesting. Data were collected in 36 permanent sample plots (0.25ha) randomly distributed among treatments (T1 \u2013 Logged forest, harvesting the stem of commercial trees; T2 \u2013 Logged forest, harvesting the stem and coarse woody debris) and control (T0 unlogged forest). Three growth phases of the forest were considered: mature (DBH > 40cm); building forest (10cm < DBH < 40cm); and gaps (occurrence of a canopy gap and a few or no tree with DBH > 10cm). The homogeneity of variances of sub-plots between treatments, growth phases and years was tested by the Bonferroni test, according to the statistics of Bartlett and Levene. An analysis of variance was applied on the number of sub-plots by phases, years and treatments at a 0.005 significance level. The Tukey test was applied for analyzing the interaction between the phases and years. Before logging the percentage of growth phases were: 57.0% building forest, 38.9% mature forest and 4.1% canopy gaps. Logging reduced the areas of mature forest and building forest, increasing the number of canopy gaps, but this increase had no statistical difference. One year after logging the area of mature forest (38.4%) and building forest (53.1%) increased while the areas of gaps (8.4%) decreased. Three years after logging the percentage of mature forest (37.1%), building forest (57.9%) and gaps (5.0%) were similar to those found before logging. The forest growth phases were not influenced by logging, over the study period. The study forest showed that it is able to grow, closing the canopy gaps, even in a short period of time

Dissemination and teaching of astronomy and physics through informal approaches.

A Astronomia ? uma das mais antigas ci?ncias naturais, tendo sido desenvolvida por diferentes civiliza??es e com distintos prop?sitos nos ?ltimos mil?nios. No Brasil, v?rios t?picos astron?micos permeiam a educa??o b?sica, tanto em n?vel fundamental quanto m?dio. Somado a isso, nas ?ltimas d?cadas vem crescendo o n?mero de pesquisas e o interesse pela divulga??o cient?fica e pelo ensino em espa?os n?o-formais de educa??o. As atividades educacionais e a divulga??o cient?fica nesse contexto, se bem exploradas, podem contribuir para a socializa??o e a populariza??o de conhecimentos sobre Astronomia. Al?m disso, podem servir de suporte ? forma??o de professores e alunos. Dessa forma, o debate sobre o tema ? importante e deve ser instigado tanto no ?mbito n?o acad?mico quanto no ?mbito da forma??o docente e discente. Frente a isso, um projeto de extens?o da Coordenadoria de F?sica (CODAFIS) do Instituto Federal de Minas Gerais - Campus Ouro Preto (IFMG-OP) foi iniciado em 2011, oferecendo observa??es e atividades sobre Astronomia para a popula??o local e das cidades vizinhas. Desde ent?o, mais de 7.000 pessoas j? participaram das a??es, demonstrando o imenso potencial do tema. As discuss?es sobre Astronomia levam normalmente a discuss?es sobre F?sica, quando conceitos e v?rios outros assuntos podem ser tratados de forma aplicada, fomentando o interesse por esses temas. No entanto, atividades mal elaboradas ou mal desenvolvidas podem gerar rea??es adversas no p?blico, causando resist?ncia com rela??o ao assunto. Assim, esse artigo tem como objetivo principal identificar elementos que podem culminar com a n?o efetividade das atividades de observa??o. Al?m disso, busca-se identificar par?metros que sejam determinantes para o ?xito das a??es, al?m de compartilhar conhecimentos emp?ricos obtidos com o desenvolvimento do projeto e encorajar grupos, acad?micos ou n?o, a desenvolverem atividades astron?micas similares em ambientes formais e n?o-formais de ensino e tamb?m em diferentes regi?es do pa?s.Astronomy is one of the oldest natural sciences and have been developed by different civilizations and with different purposes in the last millennia. In Brazil, several astronomical topics are teached in basic education, both at the fundamental and medium levels. In addition, the number of researches and activities about scientific dissemination and teaching in non-formal places is increasing. Educational activities and scientific dissemination in this context, if well done, can contribute to the socialization and popularization of astronomy knowledge. Besides that, they can help to improve the knowledge of teachers and students. In this way, the debate on the subject is important and should be instigated both in the non-academic context and in the scope of teacher and student training. In this way, a practical project of the Physics Department (CODAFIS) of the Federal Institute of Minas Gerais - Campus Ouro Preto (IFMG-OP) was started in 2011, offering observations and activities on Astronomy for the local population and neighboring cities. Since then, more than 7,000 people have attended the actions, which shows the large potential of the theme. Astronomy discussions naturally lead to Physics, when concepts and many other subjects can be treated in an applied way. In general, people are more interested in activities in this context than in traditional teaching environments. However, poorly designed or poorly developed activities can generate adverse reactions in the public, leading to dislike on the subject. Thus, this article?s main objective is to identify elements that can culminate with the non-effectiveness of the observation activities. In addition, it seeks to identify parameters that are determinant for the success of the actions, in addition to sharing empirical knowledge obtained with the development of the project and to encourage groups, academic or otherwise, to develop similar astronomical activities in formal and non-formal educational environments and also in different regions of the country

Massive rotator cuff tears: functional outcome after debridement or arthroscopic partial repair

Background The surgical treatment of massive rotator cuff tears (RCT) is still controversial and can be based on a variety of different surgical repair methods. This study investigated the effectiveness of arthroscopic debridement or arthroscopic partial repair in patients with massive RCT. Materials and methods This prospective, randomized study involved forty-two patients with massive RCT (fatty infiltration stage 3 or 4) treated with either arthroscopic partial repair or arthroscopic debridement were selected to detect possible differences in functional outcome. Both groups were matched according to age and gender. Patients were examined before, and 16 ± 3 and 24 ± 2 months after surgery. The status of the rotator cuff repair was determined using ultrasonographic evaluation. Results Regardless of the treatment group, postoperative results demonstrated highly significant improvements compared with preoperative values in most parameters. The overall Constant score in the partial repair group was superior to the outcome in the debridement group (P \ 0.01, F = 8.561), according to better results in abductio

The Maastricht Ultrasound Shoulder pain trial (MUST): Ultrasound imaging as a diagnostic triage tool to improve management of patients with non-chronic shoulder pain in primary care

<p>Abstract</p> <p>Background</p> <p>Subacromial disorders are considered to be one of the most common pathologies affecting the shoulder. Optimal therapy for shoulder pain (SP) in primary care is yet unknown, since clinical history and physical examination do not provide decisive evidence as to the patho-anatomical origin of the symptoms. Optimal decision strategies can be furthered by applying ultrasound imaging (US), an accurate method in diagnosing SP, demonstrating a clear relationship between diagnosis and available therapies. Yet, the clinical cost-effectiveness of applying US in the management of SP in primary care has not been studied. The aim of this paper is to describe the design and methods of a trial assessing the cost-effectiveness of ultrasound imaging as a diagnostic triage tool to improve management of primary care patients with non-chronic shoulder pain.</p> <p>Methods/Design</p> <p>This randomised controlled trial (RCT) will involve 226 adult patients with suspected subacromial disorders recruited by general practitioners. During a Qualification period of two weeks, patients receive care as usual as advised by the Dutch College of General Practitioners, and patients are referred for US. Patients with insufficient improvement qualify for the RCT. These patients are then randomly assigned to the intervention or the control group. The therapies used in both groups are the same (corticosteroid injections, referral to a physiotherapist or orthopedic surgeon) except that therapies used in the intervention group will be tailored based on the US results. Ultrasound diagnosed disorders include tendinopathy, calcific tendinitis, partial and full thickness tears, and subacromial bursitis. The primary outcome is patient-perceived recovery at 52 weeks, using the Global Perceived Effect questionnaire. Secondary outcomes are disease specific and generic quality of life, cost-effectiveness, and the adherence to the initial applied treatment. Outcome measures will be assessed at baseline, 13, 26, 39 and 52 weeks after inclusion. An economic evaluation will be performed from both a health care and societal perspective with a time horizon of 52 weeks.</p> <p>Discussion</p> <p>The results of this trial will give unique evidence regarding the cost-effectiveness of US as a diagnostic triage tool in the management of SP in primary care.</p

Detection and identification of Xanthomonas pathotypes associated with citrus diseases using comparative genomics and multiplex PCR.

Background. In Citrus cultures, three species of Xanthomonas are known to cause distinct diseases. X. citri subsp. citri patothype A, X. fuscans subsp. aurantifolii pathotypes B and C, and X. alfalfae subsp. citrumelonis, are the causative agents of cancrosis A, B, C, and citrus bacterial spots, respectively. Although these species exhibit different levels of virulence and aggressiveness, only limited alternatives are currently available for proper and early detection of these diseases in the fields. The present study aimed to develop a new molecular diagnostic method based on genomic sequences derived from the four species of Xanthomonas. Results. Using comparative genomics approaches, primers were synthesized for the identification of the four causative agents of citrus diseases. These primers were validated for their specificity to their target DNA by both conventional and multiplex PCR. Upon evaluation, their sensitivity was found to be 0.02 ng/?l in vitro and 1.5 ? 104 CFU ml?1 in infected leaves. Additionally, none of the primers were able to generate amplicons in 19 other genomes of Xanthomonas not associated with Citrus and one species of Xylella, the causal agent of citrus variegated chlorosis (CVC). This denotes strong specificity of the primers for the different species of Xanthomonas investigated in this study. Conclusions. We demonstrated that these markers can be used as potential candidates for performing in vivo molecular diagnosis exclusively for citrus-associated Xanthomonas. The bioinformatics pipeline developed in this study to design specific genomic regions is capable of generating specific primers. It is freely available and can be utilized for any other model organism

Search for the standard model Higgs boson in the H to ZZ to 2l 2nu channel in pp collisions at sqrt(s) = 7 TeV

A search for the standard model Higgs boson in the H to ZZ to 2l 2nu decay channel, where l = e or mu, in pp collisions at a center-of-mass energy of 7 TeV is presented. The data were collected at the LHC, with the CMS detector, and correspond to an integrated luminosity of 4.6 inverse femtobarns. No significant excess is observed above the background expectation, and upper limits are set on the Higgs boson production cross section. The presence of the standard model Higgs boson with a mass in the 270-440 GeV range is excluded at 95% confidence level.Comment: Submitted to JHE

Azimuthal anisotropy of charged particles at high transverse momenta in PbPb collisions at sqrt(s[NN]) = 2.76 TeV

The azimuthal anisotropy of charged particles in PbPb collisions at nucleon-nucleon center-of-mass energy of 2.76 TeV is measured with the CMS detector at the LHC over an extended transverse momentum (pt) range up to approximately 60 GeV. The data cover both the low-pt region associated with hydrodynamic flow phenomena and the high-pt region where the anisotropies may reflect the path-length dependence of parton energy loss in the created medium. The anisotropy parameter (v2) of the particles is extracted by correlating charged tracks with respect to the event-plane reconstructed by using the energy deposited in forward-angle calorimeters. For the six bins of collision centrality studied, spanning the range of 0-60% most-central events, the observed v2 values are found to first increase with pt, reaching a maximum around pt = 3 GeV, and then to gradually decrease to almost zero, with the decline persisting up to at least pt = 40 GeV over the full centrality range measured.Comment: Replaced with published version. Added journal reference and DO

Search for the standard model Higgs boson decaying into two photons in pp collisions at sqrt(s)=7 TeV

A search for a Higgs boson decaying into two photons is described. The analysis is performed using a dataset recorded by the CMS experiment at the LHC from pp collisions at a centre-of-mass energy of 7 TeV, which corresponds to an integrated luminosity of 4.8 inverse femtobarns. Limits are set on the cross section of the standard model Higgs boson decaying to two photons. The expected exclusion limit at 95% confidence level is between 1.4 and 2.4 times the standard model cross section in the mass range between 110 and 150 GeV. The analysis of the data excludes, at 95% confidence level, the standard model Higgs boson decaying into two photons in the mass range 128 to 132 GeV. The largest excess of events above the expected standard model background is observed for a Higgs boson mass hypothesis of 124 GeV with a local significance of 3.1 sigma. The global significance of observing an excess with a local significance greater than 3.1 sigma anywhere in the search range 110-150 GeV is estimated to be 1.8 sigma. More data are required to ascertain the origin of this excess.Comment: Submitted to Physics Letters