Polymerization shrinkage and porosity profile of dual cure dental resin cements with different adhesion to dentin mechanisms

This research aims to probe the porosity profile and polymerization shrinkage of two different dual cure resin cements with different dentin bonding systems. The self‐adhesive resin cement RelyX U200 (named RU) and the conventional Allcem Core (named AC) were analyzed by x‐ray microtomography (μCT) and Scanning Electron Microscopy (SEM). Each cement was divided into two groups (n = 5): dual‐cured (RUD and ACD) and self‐cured (RUC and ACC). μCT demonstrated that the method of polymerization does not influence the porosity profile but the polymerization shrinkage. Fewer concentration of pores was observed for the conventional resin cement (AC), independently the method used for curing the sample. In addition, SEM showed that AC has more uniform surface and smaller particle size. The method of polymerization influenced the polymerization shrinkage, since no contraction for both RUC and ACC was observed, in contrast with results from dual‐cured samples. For RUD and ACD the polymerization shrinkage was greater in the lower third of the sample and minor in the upper third. This mechanical behavior is attributed to the polymerization toward the light. µCT showed to be a reliable technique to probe porosity and contraction due to polymerization of dental cements.     

Effects of Sedentarism and Treadmill Training in Mechanical Properties of Muscles of Ovariectomized Rats with High-Fat Diet

The aim of this study is to evaluate the ability of physical training in the maintenance of muscle strength in rats with HFD （high-fat diet） after OVX （ovariectomy）. Eighty Wistar rats are at eight weeks of age and weight 200 g which divided into 8 groups （n = 10） and treated for 12 weeks： GA： OVX ＋ ND （normal diet）, GB： OVX ＋ ND ＋ training, GC： sham ＋ ND, GD： sham ＋ ND ＋ training, GE： OVX ＋ HFD, GF： OVX ＋ HFD ＋ training, GG： sham ＋ HFD and GH： sham ＋ HFD ＋ training. HFD consists of standard ration for rats with addition of 30% lipids. In training groups, physical training five training/week was conducted on a treadmill with adaptation period of three weeks up to 18 m/s for one hour, training were performed for 12 weeks. The sedentary animals remained in individual box. To analyze the effects of training and diet, tensile strength tests of the gastrocnemius muscles were conducted： the speed of 0.1 mm/min. Analysis of variance was performed to compare groups. The mean （SD） obtained for the maximum load （N） were： GA 57.77 （6.89）, GB 62.74 （5.07）, GC 49.45 （6.06）, GD 59.42 （5.26） and GE 55.58 （4.72）, GF 62.50 （4.56）, GG 58.35 （4.54） and GH 56.67 （5.87）, respectively. There were no differences for maximum load between surgeries （p = 0.004） and between treatments （p = 0.000）. Differences were found also for the relationship surgery diet treatment （p = 0.007）. For the variable stiffness （N/mm）, there were not statistically significant differences： GA 5.03 （0.72）, GB 5.08 （1.09）, GC 5.17 （0.53）, GD 5.35 （0.80）, GE 5.52 （1.20）, GF 5.36 （1.07）, GG 4.83 （1.03） and GH 5.40 （0.73）. For the toughness （N/mm）, there were differences between treatments （p = 0.010） and the ratio diet treatment （p = 0.024）： GA 455.00 （107.21）, GB 541.96 （126.80）, GC 394.97 （84.67）, GD 566.90 （157.07）; GE 424.63 （113.03）, GF 478.07 （106.03）; GG 517.44 （98.65?     

金属塑性成形过程CSPH无网格法数值模拟

应用微可压缩刚塑性材料的流动法则,采用修正的光滑粒子力学(Corrected smooth particle hydrodynamics, CSPH)无网格法,自行开发了求解金属方棒压缩和圆棒压缩等金属塑性成形过程应用程序。提出一种简单的求解体积应变速率的光滑技术,该技术使应力场计算结果能得到较好的改善。采用CSPH无网格法求解纯铝和Al6060铝合金材料压缩过程得到的速度场和应力场结果与有限元法计算结果以及试验数据进行了分析比较。结果表明, CSPH法能够较好地求解金属大变形过程,为今后进一步分析复杂金属变形问题提供了良好的研究手段。     

Treatment of Chronic Kidney Disease with Extracellular Vesicles from Mesenchymal Stem Cells and CD133+ Expanded Cells: A Comparative Preclinical Analysis

Chronic kidney disease (CKD) is characterized by structural abnormalities and the progressive loss of kidney function. Extracellular vesicles (EVs) from human umbilical cord tissue (hUCT)-derived mesenchymal stem cells (MSCs) and expanded human umbilical cord blood (hUCB)-derived CD133⁺ cells (eCD133⁺) maintain the characteristics of the parent cells, providing a new form of cell-free treatment. We evaluated the effects of EVs from hUCT-derived MSCs and hUCB-derived CD133⁺ cells on rats with CDK induced by an adenine-enriched diet. EVs were isolated by ultracentrifugation and characterized by nanoparticle tracking analysis (NTA) and electron microscopy. The animals were randomized and divided into the MSC-EV group, eEPC-EV group and control group. Infusions occurred on the seventh and 14th days after CKD induction. Evaluations of kidney function were carried out by biochemical and histological analyses. Intense labeling of the α-SMA protein was observed when comparing the control with MSC-EVs. In both groups treated with EVs, a significant increase in serum albumin was observed, and the increase in cystatin C was inhibited. The results indicated improvements in renal function in CKD, demonstrating the therapeutic potential of EVs derived from MSCs and eCD133⁺ cells and suggesting the possibility that in the future, more than one type of EV will be used concurrently.     

Physical examination of arteriovenous fistula: The influence of professional experience in the detection of complications

Vascular access is one of the leading causes of mobilization of financial resources in health systems for people with chronic kidney disease on hemodialysis. Physical examination of the arteriovenous fistula (AVF) has demonstrated its effectiveness in identifying complications. We decided to evaluate the influence of nurses' professional experience in the detection of complications of the AVF (venous stenosis and steal syndrome). The study took place in eight hemodialysis centers between May and September of 2011 in the north of Portugal. Sample was constituted by registered nurses. The nurses involved in the experiment were divided in two groups: those who had more than 5 years of experience and those who had less than 5 years of experience. Ninety‐two nurses participated in the study: 34 nurses had less than 5 years of professional experience and 58 had more than 5 years of professional experience. In the practices considered by nurses in the detection of venous stenosis, there were no differences observed between the groups (P > 0.05). In steal syndrome, there were no differences observed between the groups in the practices of the nurses in the detection of this complication of the AVF (P > 0.05). We concluded that professional experience does not influence the detection of venous stenosis and steal syndrome.     

Technological and organizational change in the Brazilian computer industry: A case study

Abstract

This article gives an account of the results of a case study undertaken at a pioneer and particularly prominent firm in the Brazilian computer industry: COBRA — Computadores e Sistemas Brasileiros SA.

The study is part of a research project¹ whose main goal is the identification of viable organizational and technological options that could enhance the performance of firms in the Brazilian electro‐electronics industry. Among the more important findings, it was observed that the firm has the potential to evolve to a more flexible structure, in keeping with the new requirements of the probable future market scenarios within its sector.

Everything indicated, however, that the main constraining factors for bringing about such a structure were connected with the firm's culture and beliefs and with the indirect influence of the National Policy of Information Technology upon these. An hypothesis was put forward for an organizational model, and the necessary supportive computerized technology, which could be particularly appropriate in view of the impending deregulation, of the Brazilian computer industry. Also, in the scope of the current discussion on the restructuring of this industry in terms of a greater concentration, an alternative to the prevailing school of thought was proposed, and for whose success the organizational model at issue purports to be particularly relevant.     

Can the revolution be optimised? Oh yes it can! But,maybe not. Report on the one day symposium on “Varieties of Enactivism”

The “Varieties of Enactivism: A Conceptual Geography” 4th April 2014, was a one day symposium which took place at Goldsmith University, London. The symposium had the explicit aim of clarifying the status of enactive cognitive science both as a unified paradigm for cognitive science and in relation to the broader embodied cognition framework. In what follows I offer a brief summery of the various talks followed by some thoughts on the current state of play within enactivism.     

Survey and comparison of message authentication solutions on wireless sensor networks

Security is an important concern in any modern network. This also applies to Wireless Sensor Networks (WSNs), especially those used in applications that monitor sensitive information (e.g., health care applications). However, the highly constrained nature of sensors imposes a difficult challenge: their reduced availability of memory, processing power and energy hinders the deployment of many modern cryptographic algorithms considered secure. For this reason, the choice of the most memory-, processing- and energy-efficient security solutions is of vital importance in WSNs. To date, a number of extensive analyses comparing different encryption algorithms and key management schemes have been developed, while very little attention has been given to message authentication solutions. In this paper, aiming to close this gap, we identify cipher-based Message Authentication Codes (MACs) and Authenticated Encryption with Associated Data (AEAD) schemes suitable for WSNs and then evaluate their features and performance on a real platform (TelosB). As a result of this analysis, we identify the recommended choices depending on the characteristics of the target network and available hardware.     

Evaluation of incremental learning algorithms for HMM in the recognition of alphanumeric characters

We present an evaluation of incremental learning algorithms for the estimation of hidden Markov model (HMM) parameters. The main goal is to investigate incremental learning algorithms that can provide as good performances as traditional batch learning techniques, but incorporating the advantages of incremental learning for designing complex pattern recognition systems. Experiments on handwritten characters have shown that a proposed variant of the ensemble training algorithm, employing ensembles of HMMs, can lead to very promising performances. Furthermore, the use of a validation dataset demonstrated that it is possible to reach better performances than the ones presented by batch learning.     

Volatile fraction of DOP “Castelo Branco” cheese: Influence of breed

“Castelo Branco” cheese is a Portuguese DOP cheese made from raw ewe’s milk coagulated with Cynara cardunculus, ripened for at least 40 days. “Merino da Beira Baixa” pure race is frequently used to produce milk for this cheese, however, exotic races such as Assaf and crusade of these two races are also used. The aim of this work has been to compare the volatile profile and sensory characteristics of DOP “Castelo Branco” cheeses manufactured during winter season with milk of breeds from Merino, Assaf and crusade of these two races and identify volatile compounds that can distinguish these cheeses.