Layer‐By‐Layer Electropeeling of Organic Conducting Material Imaged In Real Time

Soft materials comprising low‐molecular‐weight organic molecules are attracting increasing interest because of their importance in the development of a number of emerging areas in nanoscience and technology, including molecular electronics, nanosystems for energy conversion, and devices in the widest sense. Their interaction with electrodes and their behavior under electric fields is a topic of vital significance for these areas, and about which very little is known. Here unprecedented evidence is presented for the controlled peeling of organic molecular material when a voltage is applied between the conducting system and the conducting probe of a scanning force microscope. The rate of removal of the material from the surface of the bulk conducting supramolecular material can be tuned. It depends on the potential applied and is initiated only above a threshold value of 200 mV. The results indicate the importance of electric fields on the stability and performance of conducting organic systems at the nanoscale.     

Relationships between memory models

There have been many proposals of shared memory systems, each one providing different types of memory coherence for interprocess communication. However, they have usually been defined using different formalisms. This makes it difficult to compare among them the different proposals put forward. In this paper we present a formal framework for specifying memory models with different coherency properties. We specify most of the known shared memory models using our framework, showing some of the relationships that hold among them.     

External maintenance rate prediction and design concepts for high reliability and availability on space station Freedom

As envisioned in 1990^*, international space station Freedom (SSF) was to be a large, complex, multi-purpose manned facility with a 30-year design life. The presence of a crew and the size of the investment would require high reliability and availability for safety- and mission-critical systems, but even with these requirements satisfied, long life and complexity would make equipment failure and repair inevitable. Recognizing this fact, in 1990 NASA and its contractors performed a study of the maintainability of the then-current space station configuration. Based on well-founded predictions of equipment failure rates, life limits, maintenance rate factors, and repair times, maintenance on equipment outside the pressurized modules of the station alone would have absorbed more than 3000 crew hours per year, which was clearly prohibitive. The chief reason for this maintenance overload was not the unreliability of equipment; it was the sheer number of components present. This paper summarizes this study, and presents a number of design and operational concepts which promise to alleviate the maintenance overload, many of which have been adopted in the current design.The central recommendation was to think of Freedom as a long-term ‘facility’ analogous to a ground-based research laboratory or manufacturing plant, rather than as a ‘space mission’. This philosophy leads to placing as much emphasis on maintainability as reliability in design; rethinking conventional manned-spacecraft design rules such as ‘fail-op-fail-op-fail-safe,’ which contributed heavily to the complexity of the baseline configuration; prioritizing maintenance by time-to-effect as well as ‘criticality,’ and zero-basing systems to wring out excessive complexity while retaining acceptable performance and safety.     

Proportional BIC sensor for current testing

A new design of a BIC sensor for current testing static CMOS circuits is proposed. It is based on a lateral BJT device which is easy to incorporate in any standard CMOS process. The design diverts a fraction of the I _DDQ current from the cell under test and a resistive component generates a voltage proportional to I _DDQ . Additional features are the possibility of continuous measure of i _dd and increased speed of this sensor compared with sensors based on the current integration principle. The design does not have substrate currents due to the parasitic vertical BJTs. Experimental work on the sensor is reported.     

Social class, education, and smoking cessation: Long-term follow-up of patients treated at a smoking cessation unit.

Our objective was to examine social class and educational differences in long-term smoking cessation success among a cohort of smokers attending a specialized smoking clinic. We studied sustained abstinence after cessation among 1,516 smokers (895 men and 621 women) treated for smoking cessation between 1995 and 2001 at a university teaching hospital in the metropolitan area of Barcelona, Spain. We calculated 1-year and long-term (up to 8-year) abstinence probabilities by means of Kaplan-Meier curves and the hazard ratio of relapse by means of Cox regression, after adjusting for other predictors of relapse. Overall abstinence probability was .277 (95% CI = .254-.301). Men and women in social classes IV-V had significant hazard ratios of relapse after long-term follow-up (men: 1.36, 95% CI = 1.07-1.72; women: 1.60, 95% CI = 1.24-2.06), as compared with patients in social classes I-II. The same independent effect was observed for education: Men and women with primary or less than primary studies had higher hazard ratios of relapse (men: 1.75, 95% CI = 1.35-2.25; women: 1.92, 95% CI = 1.51-2.46), as compared with patients with a university degree. Similar estimates were obtained after adjustment for stage of change, Fagerstr?m score for nicotine dependence, and type of treatment. Patients of lower socioeconomic status are at higher risk of relapse, and this association is independent of other well-known predictors of relapse. Social differences have to be taken into account in the clinical setting when tailoring specific actions to treat smoking dependence.     

Pre‐reservation of Resources and Controlled Loops for Contention Resolution in OBS Networks

A new scheme to alleviate contention in optical burst switching networks is proposed. It consists of preventively reserving resources in a node, to be used if resources are busy on the next hop node. The burst is sent back to the preceding node and then resent forward. Simulations are carried out to assess the feasibility of the proposed scheme. Its performance is compared with that of contention resolution based on deflection routing.     

Selective Sharing of Load Current Components Among Parallel Power Electronic Interfaces in Three-phase Four-wire Stand-alone Microgrid

This paper investigates selective sharing of load current components among the parallel operation of distributed generators (DGs) in three-phase four-wire stand-alone microgrids. The proposed control method is based on master-slave operation of DGs, and the goal of selective sharing of load current components is to have DGs located in close proximity of the load operating in slave mode, in order to inject their available energy and also compensate the non-active load current components, while the distant DGs might operate in master mode to share the remaining load autonomously. Droop control is employed due to impracticality of communication at remote nodes, and resistive line impedance compensation is adopted to decouple active and reactive power controllers and ensure proper active power sharing among master DGs, irrespective of the mitigation of non-active current components by the slave inverters. The sharing factors for each current component are determined by a higher level control. The Conservative Power Theory (CPT) decompositions provide decoupled power and current references for the inverters, resulting in a selective sharing strategy. The principles supporting the developed control strategy are discussed, and the effectiveness of the control is demonstrated through computational simulations using PSIM software.     

Altered Fatty Acid Metabolism-Related Gene Expression in Liver from Morbidly Obese Women with Non-Alcoholic Fatty Liver Disease

Lipid accumulation in the human liver seems to be a crucial mechanism in the pathogenesis and the progression of non-alcoholic fatty liver disease (NAFLD). We aimed to evaluate gene expression of different fatty acid (FA) metabolism-related genes in morbidly obese (MO) women with NAFLD. Liver expression of key genes related to de novo FA synthesis (LXRα, SREBP1c, ACC1, FAS), FA uptake and transport (PPARγ, CD36, FABP4), FA oxidation (PPARα), and inflammation (IL6, TNFα, CRP, PPARδ) were assessed by RT-qPCR in 127 MO women with normal liver histology (NL, n = 13), simple steatosis (SS, n = 47) and non-alcoholic steatohepatitis (NASH, n = 67). Liver FAS mRNA expression was significantly higher in MO NAFLD women with both SS and NASH compared to those with NL (p = 0.003, p = 0.010, respectively). Hepatic IL6 and TNFα mRNA expression was higher in NASH than in SS subjects (p = 0.033, p = 0.050, respectively). Interestingly, LXRα, ACC1 and FAS expression had an inverse relation with the grade of steatosis. These results were confirmed by western blot analysis. In conclusion, our results indicate that lipogenesis seems to be downregulated in advanced stages of SS, suggesting that, in this type of extreme obesity, the deregulation of the lipogenic pathway might be associated with the severity of steatosis.     

A surface mesh smoothing and untangling method independent of the CAD parameterization

A method to optimize triangular and quadrilateral meshes on parameterized surfaces is proposed. The optimization procedure relocates the nodes on the surface to improve the quality (smooth) and ensures that the elements are not inverted (untangle). We detail how to express any measure for planar elements in terms of the parametric coordinates of the nodes. The extended measures can be used to check the quality and validity of a surface mesh. Then, we detail how to optimize any Jacobian-based distortion measure to obtain smoothed and untangled meshes with the nodes on the surface. We prove that this method is independent of the surface parameterization. Thus, it can optimize meshes on CAD surfaces defined by low-quality parameterizations. The examples show that the method can optimize meshes composed by a large number of inverted elements. Finally, the method can be extended to obtain high-order meshes with the nodes on the CAD surfaces.     

Comparison of a low molecular weight and a macromolecular surfactant as foaming agents for injectable self setting hydroxyapatite foams: Polysorbate 80 versus gelatine

Hydroxyapatite foams are potential synthetic bone grafting materials or scaffolds for bone tissue engineering. A novel method to obtain injectable hydroxyapatite foams consists in foaming the liquid phase of a calcium phosphate cement. In this process, the cement powder is incorporated into a liquid foam, which acts as a template for macroporosity. After setting, the cement hardens maintaining the macroporous structure of the foam. In this study a low molecular weight surfactant, Polysorbate 80, and a protein, gelatine, were compared as foaming agents of a calcium phosphate cement. The foamability of Polysorbate 80 was greater than that of gelatine, resulting in higher macroporosity in the set hydroxyapatite foam and higher macropore interconnectivity. Gelatine produced less interconnected foams, especially at high concentrations, due to a higher liquid foam stability. However it increased the injectability and cohesion of the foamed paste, and enhanced osteoblastic-like cell adhesion, all of them important properties for bone grafting materials.