Ground bounce modelling for digital gigascale integrated circuits

In the paper, an analytical model for ground bounce noise evaluation taking into account the interdependence between I_DD switching current and V_DD noise voltage is presented. The model shows the discrepancies from general accepted assumption of independence between the two variables. The main conclusion is that noise calculations using the independence assumption cause an overestimation of the noise levels. The results are verified through realistic simulations and for different technology nodes and accurate analysis of two canonical circuits.     

Risk factors associated with hemoglobin levels and nutritional status among Brazilian children attending daycare centers in Sao Paulo City, Brazil

Like many other developing countries, Brazil has been going a nutritional transition which presence both malnutrition and overweight. Stunting and overweight are the major public health problems in Brazilian children. The objective of this study was to document the prevalence of stunting, overweight and anemia in preschool children and examine if those nutritional problems are related; also identify if these nutritional problems have the same risk factors. Data from the "Efficient Daycare Center Project" which include 270 children attending nurseries of eight daycare centers in Sao Paulo city, Brazil were used for this study. Data on height and weight were converted to z-scores using WHO anthro software. Hemoglobin (Hb) concentrations were determined on finger-prick blood samples. The co-occurrence of stunting, overweight and anemia was investigated by contingency tables a log-linear model. Univariate and multiple regression analyses were performed to estimate the association of HAZ, WAZ, WHZ and Hb levels with their risk factors. The results showed high prevalence of overweight (22.2%), risk of stunting (22.6%) and anemia (37%). Percent of daycare attendance, age, number of siblings under 5 years old and per capita income are associated with Hb levels. This study provides evidence that Brazil is going through a nutritional transition and suggest that the adoption of public policies to expand and improve services in daycare centers may help to prevent multi-nutritional problems in preschool children.     

Risk analysis of surveillance requirements including their adverse effects

Technical specifications for nuclear power plants require periodic surveillance testing of the standby systems important to safety. This regulatory requirement is imposed to assure that the systems will start and perform their intended functions in the event of plant abnormality. However, operating experience suggests that, in addition to the beneficial effects of detecting latent faults, the tests may have adverse effects on the plant's operation or equipment. This paper defines those adverse effects of testing from a risk perspective, and then presents a method to quantify their associated risk impact, focusing on plant transients and the wear-out of safety systems. The method, based on probabilistic safety assessment, is demonstrated by applying it to several surveillance tests conducted at boiling water reactors. The insights from this evaluation can be used to determine risk-effective intervals for surveillance tests.     

The Global Crisis and Academic Communication： The Challenge of Social Networks in Research

The global economic crisis is seriously affecting academic research. The situation is provoking some big changes and an urgent need to seek alternatives to traditional models. It is as if the academic community was reinventing itself; and this reinvention is happening online. Faced with a lack of funding, researchers have determined to help each other develop their projects and they are doing so on social knowledge networks that they have created for this mission. The purpose of this paper is to analyze different social networks designed for academic online research. To this end, we have made a selection of these networks and established the parameters for their study in order to determine what they consist of, what tools they make use of, what advantages they offer and the degree to which they are bringing about a revolution in how research is carried out. This analysis is conducted from both a qualitative and a quantitative perspective, allowing us to identify the percentage of these networks that approach what would be the ideal social knowledge network. As we will be able to confirm, the closer they are to this ideal, the more effective they will be and the better future they will have, which will also depend on the commitment of users to participation and the quality of their contributions.     

Nanoparticle Assisted Mechanical Delamination for Freestanding High Performance Organic Devices

Organic electronics has the potential to be incorporated in any kind of surface morphology for wearable or fully portable applications. Unfortunately when organic devices, such as solar cells, are fabricated on flexible substrates, the device performance is severely limited unless the physical properties of such substrates are carefully chosen. Here, it is demonstrated that layers of nanoparticles with a size gradient distribution can be used to obtain high performance solar cell devices that can be effectively delaminated from an original flat and rigid glass substrate. Such sacrificial nanoparticles layers are incorporated in between the glass substrate and the semitransparent electrode of a polymer:fullerene (PTB7:PC₇₁BM) cell. After the cell delamination, freestanding flexible devices with power conversion efficiencies as high as 7.12% are obtained, which corresponds to 90% of the performance of the same cell fabricated on a standard glass smooth surface.     

Performance-driven processor allocation

In current multiprogrammed multiprocessor systems, to take into account the performance of parallel applications is critical to decide an efficient processor allocation. In this paper, we present the performance-driven processor allocation policy (PDPA). PDPA is a new scheduling policy that implements a processor allocation policy and a multiprogramming-level policy, in a coordinated way, based on the measured application performance. With regard to the processor allocation, PDPA is a dynamic policy that allocates to applications the maximum number of processors to reach a given target efficiency. With regard to the multiprogramming level, PDPA allows the execution of a new application when free processors are available and the allocation of all the running applications is stable, or if some applications show bad performance. Results demonstrate that PDPA automatically adjusts the processor allocation of parallel applications to reach the specified target efficiency, and that it adjusts the multiprogramming level to the workload characteristics. PDPA is able to adjust the processor allocation and the multiprogramming level without human intervention, which is a desirable property for self-configurable systems, resulting in a better individual application response time.     

Evaluation of allowed outage time considering a set of plant configurations

Allowed outage time (AOT) is the maximum time for which certain safety equipment can be put out of the operation without the plant is put in a safer operating state. A method for risk informed evaluation of AOTs is developed, which enables consideration of a set of plant configurations in the evaluation. The method bases on risk measures obtained from probabilistic safety assessment, e.g. conditional change of core damage frequency considering selected plant configurations. The results of selected examples show that better methods and more data included into the models may reduce the conservatism in the evaluations and may contribute to increased flexibility about decisions on AOT.     

A rat mutation producing demyelination (dmy) maps to chromosome 17

A recessive mutation exhibiting severe myelin breakdown, mainly at the level of the lumbar segments of the spinal cord and without any associated inflammation, was discovered in a partially inbred rat colony. Analysis of the segregation patterns of a set of polymorphic microsatellite markers in two inter-strain crosses allowed the mapping of this autosomal recessive mutation to rat Chromosome (Chr) 17, very close to the prolactin (Prl) locus, in a region homologous to human Chr 6p21.2-22.3 and mouse Chr 13. The pathology of the demyelination process and the chromosomal localization indicate that this mutation has no known equivalent in either mouse or human.     

Cross-Layer Fast Link Adaptation for MIMO-OFDM Based WLANs

This paper considers the use of cross-layer fast link adaptation (FLA) for WLANs employing a MIMO-OFDM physical layer. A packet error rate (PER)-based FLA technique that, without loss of generality, makes use of the exponential effective SNR mapping (EESM) is proposed. Additionally, an FLA scheme relying on bit error rate (BER) metrics is introduced that simplifies the link adaptation procedure without any significant performance degradation. Results show that both PER- and BER-based FLA techniques optimize the data throughput while satisfying prescribed quality of service constraints. Channel estimation errors have also been considered, revealing the importance of good channel estimators in order for FLA strategies to work satisfactorily.