MOSFET simulation with quantum effects and nonlocal mobility model

We present a state-of-the-art two-dimensional (2-D) device simulator suitable for highly doped n-MOSFETs. Quantization effects in the inversion channel are accounted for by a self-consistent solution of the Poisson, current-continuity and Schrodinger equations. The electron charge is given by a density of electrons in the bounded levels plus a density of classically-distributed carriers. Consequently, different mobility models are used. For the former, we adopted a nonlocal, newly-developed mobility model, thus overcoming the deficiency of currently-used mobility models in the high-doping limit. We instead retained a standard local model for the classical regime. Results of the simulations are in good agreement with the experiments     

Comparison of Different Extraction Methods to Determine Phenolic Compounds in Virgin Olive Oil

A comparison between different extraction methods has been performed in order to assess their effectiveness for the analysis of total phenols (liquid–liquid extraction (LLE), liquid–liquid micro extraction (LLME), and ultrasound liquid–liquid extraction (USE)) and individual phenols (LLME, USE, and solid-phase extraction (SPE)) from virgin olive oil (VOO). Statistical analysis of the analytical data obtained for the total phenol content of a VOO, showed that LLME and USE can represent a reliable alternative to the traditional procedure based on LLE that needs more amount of sample, generates more wastes, and is more time consuming. When an olive oil spiked with phenols was used to test the efficiency of LLME, USE, and SPE methods, the statistical analysis of the data obtained for each individual phenol, again proved LLME and USE methods to be the most suitable, in terms of precision and recoveries, for this purpose. The analysis of real samples (Arbequina and Picual cultivars) confirmed the results obtained for the spiked oil.     

Wood chips size distribution in relation to blade wear and screen use

The study investigated the effect of wearing chipper knives on machine productivity, fuel consumption and particles size distribution. The test included two different tree species (poplar and pine), two tree parts (branches and logs) and two screen types (large and medium). Chip quality was defined by CEN international technical standards. Knife wear causes a significant reduction of chipping productivity and a remarkable increase of fuel consumption. The replacement of the standard wide mesh screen with a narrower screen has a similar effect, further decreasing productivity and increasing fuel consumption. For the same screen type and knife wear level, productivity and fuel consumption are the same for poplar and pine. Knife, tree species and tree part also have a significant impact on chip size distribution. Chips produced from logs always contain a smaller proportion of oversize particles and a higher proportion of accepts. For the same large mesh screen, poplar chips tend to be larger than pine chips and to contain a higher proportion of oversize particles. On the contrary, pine chips tend to be smaller and to contain a higher proportion of fines. The use of a narrower mesh screen on pine material does not seem to offer any significant reduction of oversize particles, whose presence is already very limited. Therefore, a standard large mesh screen should be used when chipping pine material.     

Thyroid carcinoma in intrathoracic goiter

While research on spinal cord injury (SCI) is abundant, few studies focus on women. This population-based study investigates differences in the prevalence of secondary conditions between 128 women and 522 men. Case managers retrospectively interviewed 650 persons regarding medical and psychological conditions secondary to SCI, as well as other life issues. Overall, males and females show more similarities than differences in the ways in which they manage life with SCI. Differences were found, though, regarding etiology of initial injury, insurance coverage, caregiver use, transportation use, medication use, and in other medical and behavioral areas. Females are significantly involved in more automobile crashes than males, while males are involved in more galls than females. Females are more reliant on Medicaid, while males report more Medicare and Worker's Compensation coverage. Females are more likely to have a paid attendant as a caregiver while males are more likely to have their spouse or parents assist. Males report more independence in their use of transportation than females. Males and females also report significant differences in the use of medication. Females are more likely to use medication any time it is a treatment option. Males are more active, use tobacco more and have more arm fractures postinjury than females.     

Defect generation statistics in thin gate oxides

We analyze data-retention experiments for flash memory arrays with thin tunnel oxide (t/sub ox/ = 5 nm). These samples show an additional conduction mechanism besides Fowler-Nordheim tunneling and stress-induced leakage current (SILC). The additional leakage contribution is analyzed with respect to the spatial distribution in the array and the shape of the current-voltage characteristics, and is interpreted as an anomalous SILC due to a two-trap leakage path. From the cycling dependence of the distribution tails related to one- and two-trap leakage, we provide evidence that the defect generation statistics is not Poissonian, but is instead correlated. Possible physical mechanisms responsible for correlated generation are also discussed.     

A statistical model for SILC in flash memories

The reliability of flash memories is strongly. limited by the stress-induced leakage current (SILC), which leads to accelerated charge-loss phenomena in a few anomalous cells. Estimating the reliability of large flash arrays requires that physically-based models for the statistical distribution of SILC are developed. In this paper, we show a physical model for the leakage mechanism in thin oxides, which is able us to explain the anomalous leakage-conduction in tail cells. The physical model is then used for a quantitative evaluation of the SILC distribution in large flash arrays. The new model can reproduce the statistics of SILC for a wide range of tunnel-oxide thickness, and can provide a straightforward estimation of the reliability for large flash arrays.     

Benthic invertebrate assemblages and species diversity patterns of the Upper Paraguay River

This paper presents the first study of the benthic invertebrate assemblages of the upper section of the Paraguay River, a major tributary to the Pantanal wetland in Brazil. Thirty‐eight sites were sampled along a 200 km section below the city of Cáceres in November 2000. Sixty‐nine species and morphospecies were identified, which were dominated by Oligochaeta and Chironomidae. Mean density of benthic invertebrates varied between 72 and 10 354 m^?2 in the meandering sector of the river, 3611–49 629 m^?2 in the straight–transitional sectors, 682–5962 m^?2 in the floodplain lakes, and 1704–2208 m^?2 in floodplain channels. Highest densities were attained in sand‐gravel sediments dominated by the psammophilous oligochaete Narapa bonettoi. The Shannon diversity index ranged from 0.75 to 2.08 and was highest in floodplain lakes. Statistical analysis (UPGMA and CCA) revealed that benthic assemblages in the floodplain habitats were clearly distinct from the riverine habitats. In the river channel, the habitats were distinguished by grain size while the floodplain habitats were mostly determined by current and silt‐clay concentration (floodplain channels) or by organic matter concentration (floodplain lakes). Conservation efforts in the Upper Paraguay area should aim to maintain the flood pulse as a permanent source of spatial and temporal habitat heterogeneity. Copyright © 2005 John Wiley & Sons, Ltd.     

Effect of uncontrolled factors in a validated liquid chromatography-tandem mass spectrometry method question its use as a reference method for marine toxins: major causes for concern

Chromatographic techniques coupled to mass spectrometry is the method of choice to replace the mouse bioassay (MBA) to detect marine toxins. This paper evaluates the influence of different parameters such as toxin solvents, mass spectrometric detection method, mobile-phase-solvent brands and equipment on okadaic acid (OA), dinophysistoxin-1 (DTX-1), and dinophysistoxin-2 (DTX-2) quantification. In addition, the study compares the results obtained when a toxin is quantified against its own calibration curve and with the calibration curve of the other analogues. The experiments were performed by liquid chromatography (LC) and ultraperformance liquid chromatography (UPLC) with tandem mass spectrometry detection (MS/MS). Three acetonitrile brands and two toxin solvents were employed, and three mass spectrometry detection methods were checked. One method that contains the transitions for azaspiracid-1 (AZA-1), azaspiracid-2 (AZA-2), azaspiracid-3(AZA-3), gimnodimine (GYM), 13-desmethyl spirolide C (SPX-1), pectenotoxin-2 (PTX-2), OA, DTX-1, DTX-2, yessotoxin (YTX), homoYTX, and 45-OH-YTX was compared in both instruments. This method operated in simultaneous positive and negative ionization mode. The other two mass methods operated only in negative ionization mode, one contains transitions to detect DTX-1, OA DTX-2, YTX, homoYTX, and 45-OH-YTX and the other only the transitions for the toxins under study OA, DTX-1, and DTX-2. With dependence on the equipment and mobile phase used, the amount of toxin quantified can be overestimated or underestimated, up to 44% for OA, 46% for DTX-1, and 48% for DTX-2. In addition, when a toxin was quantified using the calibration curve of the other analogues, the toxin amount obtained is different. The maximum variability was obtained when DTX-2 was quantified using either OA or a DTX-1 calibration curve. In this case, the overestimation was up to 88% using the OA calibration curve and up to 204% using the DTX-1 calibration curve. In summary, the correct quantification of DSP toxins by MS detection depends on multiple factors. Since these factors are not taken into account in a validated protocol, these results question the convenience of having MS/MS as a reference method for protecting consumers of marine toxins, moreover if toxicity of each group is considered independently and total toxicity is not summed anymore as it is in the MBA.     

Cryptosporidium spp. and Giardia duodenalis in two areas of Galicia (NW Spain)

The aim of the present study was to investigate the environmental dispersal of Cryptosporidium spp. and Giardia duodenalis in two distinct areas (coastal and inland) in Galicia (NW Spain). Faecal samples were collected from healthy asymptomatic domestic (cows and sheep) and wild animals (deer and wild boars) in the selected areas. In each of the selected areas, samples of untreated water (influent) and of treated water (final effluent) were collected from each of the 12 drinking water treatments plants (DWTPs) and 12 wastewater treatment plants (WTPs) under study. Analysis of a single sample from each of the 635 (coastal) and 851 (inland) domestic and wild animals selected at random revealed that the prevalences of cryptosporidiosis and giardiosis in coastal area were 9.2% and 15.9% respectively, and in inland area, 13.7% and 26.7% respectively. In the coastal area, Cryptosporidium spp. oocysts were detected in influent and effluent samples from 2/12 (16.6%) DWTPs and 8/12 (66.6%) WTPs, while G. duodenalis cysts were detected in influent and effluent samples from 3/12 (25.0%) DWTPs and 12/12 (100%) WTPs. The concentrations were notably higher in WTPs; the mean parasite concentrations in the final treated effluent were 10 oocysts per litre and 137.8 cysts per litre for Cryptosporidium and Giardia, respectively. The mean concentration of G. duodenalis cysts per litre was significantly higher (P < 0.05) than the mean concentration of Cryptosporidium spp. oocysts per litre in both the influent and the effluent samples from all the treatment plants. In the coastal area, C. parvum, C. hominis and G. duodenalis assemblages A (I and II) and E were most repeatedly detected. In the inland area, C. parvum, C. andersoni and G. duodenalis assemblages A (I and II), B and E were most frequently identified.