Negative bias stress of MOS devices at high electric fields and degradation of MNOS devices

One of the most important degradation effects observed in MNOS memory transistors is a negative shift of the threshold window. This negative shift is caused by a strong increase of the density of Si‐SiO2 surface traps. This effect has been proposed to be caused by the same effect that is observed in MOS devices subjected to negative‐bias stress (NBS). In this paper, a detailed study of the increase of the number of surface traps in MOS structures after NBS at temperatures (25–125°C) and fields (400–700 MV/m) comparable to those used in MNOS devices is presented. Two different behaviors are observed. At low fields the surface‐trap density increases as t^1/4 and at high fields it increases linearly with the stress time t. The low‐field behavior is temperature and field dependent and the zero‐field activation energy is determined to be 0.3 eV. The high‐field behavior is strongly field dependent but independent of temperature. A physical model is proposed to explain the surface‐trap growth as being diffusion controlled at low fields and tunneling limited at high fields. A comparison with MNOS degradation is made and it was found to be related to the t^1/4 behavior mentioned above

Traffic Calming in India : Report on the theory of Traffic Calming and empirical trials in the city of Jaipur

The pedestrian safety problem is huge in all developing countries. The main aims of the project are therefore: 1/To understand pedestrian safety problem in a developing country, 2/To identify feasible traffic calming measures. International experiences were complemented by field studies at seven sites in the city of Jaipur. A wide range of field studies were made, out of which traffic conflict studies were most important. The main conclusion of the studies is that there is an urgent need for Traffic Calming measures in Indian cities. Pedestrians are extremely exposed and vulnerable, and the speeds are too high to allow a safe and proper communication. One main problem is that road users are not offered any comfortable and safe crossing options e.g. existing pedestrian crossings are not suited for pedestrians. The conclusion from this is that there is a “chaos” that has to be dealt with. The proposed measures are “standardised Traffic Calming measures”, primarily by introducing humps at both entrances and exits to intersections and to introduce raised footpaths in all corners to see to it to make the approaches for pedestrians as comfortable and safe as possible by preventing cars from being able to use that space. Pedestrian crossings are located close to the intersections so that pedestrians do not have to make large detours to use them. The measures that are proposed are simple which is the whole idea. Without simplicity and low costs there will never be any large scale use. Unfortunately no measures are taken yet in Jaipur, which of course will be next and very important step. When this is done, and after studies carried out, it is time to decide on studies for studying the validity of the results in other parts of Indi

Separation between pedestrians and bicyclists

In the effort to separate pedestrian and bicycle traffic from motorised traffic the solution often is to let the pedestrians and bicyclists share space. However, combined pedestrian and bicycle paths lead to problems for both pedestrians and bicyclists; for pedestrians it is a security and safety problem and for bicyclists a mobility problem. Seniors and visually impaired pedestrians are especially concerned as they often feel insecure when cyclists pass close to them, especially as they neither can see nor hear cyclists coming from behind. The safety problem is primarily linked to pedestrians walking on the bicycle side of the tracks. Designing the tracks so that the pedestrians and bicyclists keep to their side respectively is important to improve the situation. Field studies were performed at over 100 pedestrian and bicycle tracks and the results were analysed with respect to materials, separation line, flow, signs, dimensions, road markings and surroundings. The results show that the design has a great impact on whether the road users keep to their side of the pedestrian and bicycle tracks or not. The most efficient design seems to be a difference in material, asphalt on the bicycle side and tiles on the pedestrian side, together with a separation of the two sides, e.g. by paving stones or curbs. Signing has no impact at all whereas the road markings has a great impact, which is interesting both from a perceptional view point and also from the point of view that Swedish rules do not support the use of markings but signing

Yielding behaviour and interaction at bicycle crossings

The main purpose of this study was to learn more about how bicyclists and motor vehicle drivers in some Swedish cities interact at intersections and how the yielding rules, different intersection designs, vehicle flows and speed affect the behaviour. Field studies were performed at 25 crossings for six hours each. Cycle crossings on links, at three- and four-armed intersections as well as at roundabouts were studied. Preliminary results show that yielding rules are not enough to make road users behave as intended; even when there are yielding signs and markings before the bicycle crossing, 30% of the motor vehicle drivers do not yield to bicyclists. Fewer yield to bicyclists when motor vehicle speed is higher, when motor vehicle flow is larger and when bicycle flow is smaller. Speeds below 30 km/h seem to produce quite favourable conditions for an interaction with a high degree of equity, efficiency and safety for both road users no matter whether car drivers have to yield according to the rules or not. Motor vehicle drivers are most likely to give way to bicyclists when the bicycle crossing is next to a roundabout and least likely to give way when it is situated on a link. The conclusion is that there is a certain amount of drivers that do not obey the yielding rules and presumably rely on their larger mass and better protection. It is therefore very important that the road design allows for active interaction between the road user groups to get a more equal situation between motor vehicle drivers and bicyclists as well as safe and secure bicycle crossings. Speed is obviously the key issue

Disruption of the odour-mediated mating behaviour of Plodia interpunctella using high-frequency sound

Indian meal moths, Plodia interpunctella Hubner ( Lepidoptera: Pyralidae), have ears which are sensitive to high-frequency calls produced by echolocating, insectivorous bats. The influence of artificially generated, high-intensity, ultrasound signals (25 kHz, 106 dB SPL at 1 m distance) on different parameters involved in the odour-mediated mating behaviour of this species and its potential use in population control was investigated. All moths flying towards olfactory cues in flight tunnel experiments reacted strongly to a 1 s ultrasound pulse by cessation of flight and falling out of the odour plume. The source contact proportion of both male moths orienting towards the female-produced sex pheromone and of mated female moths orienting towards an oviposition cue was reduced by 40%, compared to unexposed moths. Calling females responded to the sound by retraction of the ovipositor or by falling to the ground. Long-term exposure to repetitive pulses of ultrasound suppressed female calling by up to 27%. Furthermore, mating in plastic tents was disrupted by up to 58% in ultrasound-treated tents using different sound regimens, compared to control tents. The results are discussed in relation to the potential use of ultrasound technology for the population control of pyralid stored product pests

Loss of size-selectivity at histamine-induced exudation of plasma proteins in atopic nasal airways.

Plasma proteins occur in the airway lumen in inflammatory airway diseases. This study tests the hypothesis that airway microvascular-epithelial exudation of plasma proteins, as induced by a non-injurious inflammatory mediator, is characterized by loss of size-selectivity. Using a nasal pool-device, the nasal mucosa of 10 allergic individuals, without current disease, was sequentially exposed to saline and histamine (40 and 400 microg ml(-1)). Nasal lavage fluid and blood-levels of albumin (69 kD) and alpha2-macroglobulin (720 kD) were determined. Histamine produced concentration-dependent exudation of albumin and alpha2-macroglobulin. The albumin/alpha2-macroglobulin concentration ratio of the saline lavage fluid (baseline) was 40+/-19. However, at the histamine challenges the ratios were 25+/-3 and 22+/-2, respectively, which did not differ from that of circulating plasma (22+/-2). We conclude that there is minor and size-selective luminal entry of plasma proteins at baseline. However, at concentration-dependent exudative responses to histamine, plasma proteins enter the airway lumen without being sieved. These data indicate that inflammatory stimulus-induced extravasation, lamina propria distribution and paracellular epithelial passage of plasma occur with minimal size-selectivity. Inferentially, the full immunological capacity of plasma proteins may readily be made available at the surface of human intact airway mucosa

Plasma proteins in a standardised skin mini-erosion (II): effects of extraction pressure

BACKGROUND: A standardised suction technique has been used to sample plasma proteins in dermal interstitial fluid (IF) serially for 5 to 6 days from a suction-induced skin mini-erosion. Increased protein concentrations ascribed to inflammation have been shown from day 1 onward. In this study, we assessed the effect of two different extraction pressures on IF sample composition. METHODS: Total protein concentration and the concentrations of insulin, prealbumin, albumin, transferrin, IgG and alpha-2-macroglobulin were assessed daily in healthy volunteers. Samples were extracted at 50 mmHg and 200 mmHg below the atmospheric. RESULTS: At 0 h after forming the erosion, mean total IF protein content (relative to plasma) was lower in the samples extracted at -200 mmHg than at -50 mmHg (26 +/-13% (SD) vs 48 +/-9.8%; p < 0.05). There were no significant differences at 24, 48, 72 or 96 h. Of the individual proteins, expressed as area units (AU) for area under the curve (AUC) from 0–96 h, albumin was lower in IF sampled at -200 mmHg (2.49 +/- 0.68 vs 3.08 +/- 0.36 AU; p < 0.05), as was transferrin (1.91 +/- 0.52 vs 2.40 +/- 0.42 AU; p < 0.05). Extraction volumes were significantly higher at -200 mmHg (AUC diff: 60%; p < 0.05). CONCLUSIONS: Samples of IF extracted at 0 h at -200 mmHg contained lower protein concentrations, indicating an increased water fraction and an intact sieve function of the vascular wall. The difference in protein concentration extracted at higher and lower pressure from 24 h onward was less pronounced. Lower pressure should be used to sample substances of greater molecular size

Plasma proteins in a standardised skin mini-erosion (I): permeability changes as a function of time

BACKGROUND: A standardised technique using a suction-induced mini-erosion that allows serial sampling of dermal interstitial fluid (IF) for 5 to 6 days has been described. In the present study, we studied permeability changes as a function of time. METHODS: We examined IF concentrations of total protein concentration and the concentration of insulin (6.6 kDa), prealbumin (55 kDa), albumin (66 kDa), transferrin (80 kDa), IgG (150 kDa) and alpha-2-macroglobulin (720 kDa) as a function of time, using an extraction pressure of 200 mmHg below atmospheric. RESULTS: At 0 h after forming the erosion, mean total IF protein content (relative to plasma) was 26 ± 13% (SD). For the individual proteins, the relative mean concentrations were 65 ± 36% for insulin, 48 ± 12% for albumin, 30 ± 19% for transferrin, 31 ± 15%for IgG and 19.5 ± 10% for alpha-2-macroglobulin. At 24 h, the total IF protein content was higher than at 0 h (56 ± 26% vs 26 ± 13%; p < 0.05, diff: 115%), as were some of the individual protein concentrations: prealbumin (50 ± 24 vs 25 ± 13%; p < 0.05), albumin (68 ± 21 vs 48 ± 12%; p < 0.05) and IgG (55 ± 30 vs 31 ± 15%; p = 0.05). ln the interval 24 h to 96 h the concentrations were relatively unchanged. CONCLUSIONS: The results indicate that fluid sampled at 0 h after forming the erosion represents dermal IF before the full onset of inflammation. From 24 h onward, the sampled fluid reflects a steady state of increased permeability induced by inflammation. This technique is promising as a tool for clinically sampling substances that are freely distributed in the body and as a model for studying inflammation and vascular permeability