Virtual spring damper method for nonholonomic robotic swarm self-organization and leader following

In this paper, we demonstrate a method for self-organization and leader following of nonholonomic robotic swarm based on spring damper mesh. By self-organization of swarm robots we mean the emergence of order in a swarm as the result of interactions among the single robots. In other words the self-organization of swarm robots mimics some natural behavior of social animals like ants among others. The dynamics of two-wheel robot is derived, and a relation between virtual forces and robot control inputs is defined in order to establish stable swarm formation. Two cases of swarm control are analyzed. In the first case the swarm cohesion is achieved by virtual spring damper mesh connecting nearest neighboring robots without designated leader. In the second case we introduce a swarm leader interacting with nearest and second neighbors allowing the swarm to follow the leader. The paper ends with numeric simulation for performance evaluation of the proposed control method

Cadmium in Brown Crab Cancer pagurus in Norwegian Waters

The Brown crab Cancer pagurus is appreciated as seafood and its fishery is of importance in several European countries. However, findings of high levels of cadmium have increased concern about food safety, and spatial patterns of cadmium levels have been found. Along the Norwegian coast, a sudden spatial increase in cadmium levels in brown crab from Salten region in Northern Norway (ca. 67°N) and northwards has been identified. An earlier study including sediment measurements investigated the reason for the high values in the North, and concluded that it is unlikely that an anthropogenic point source is responsible for the high cadmium levels. The main aim of this thesis was to investigate further factors that may explain the large variation of cadmium in brown crab, and whether these factors can explain the differences in cadmium levels in brown crab along the Norwegian coast, with focus on physiological factors. Conflicting values of reported cadmium levels in crab claw meat led us to evaluate the pretreatment of crabs before analyses. A strong effect of cooking and freezing was found, causing a leakage of cadmium from hepatopancreas to claw meat. The findings in crabs sampled in the North and the South of the Norwegian coast during one year, revealed that the influence of physiological factors on cadmium levels is not very pronounced in comparison to the large differences between crabs from the North and the South. However, there was a correlation between size and cadmium levels in crabs sampled in the North, indicating an accumulation of cadmium over time. As brown crabs are assumed to grow more slowly in the North, this indicates that some of the variation in cadmium between the North and the South can be explained by growth rate. Further evidence for a high potential of brown crab to accumulate cadmium has been found in a lab trial, where cadmium from food and water was traced in brown crab to compare the relative importance of the uptake routes. No depuration of cadmium was observed, indicating a high accumulation potential. Furthermore, the dietary uptake was predicted to contribute at least 98 % to the overall cadmium accumulation in brown crab in Northern Norway. This indicates that foraging and related behavior plays an important role in determining the cadmium levels in crab. As we found an indication for different foraging patterns in crabs from North and South, this might partly explain the north-south variation. The field study did not reveal a clear pattern in cadmium levels in brown crab when considering sex, moulting stage, gonad maturation stage, or season, making it difficult to develop mitigation strategies for the crab fishery in the North. Another aim of this thesis was to assess the risk of exceeding the limit of safe exposure to cadmium by the consumption of brown crab considering different consumption patterns in the Norwegian population. According to our measured cadmium level in cooked crabs from the field study, it is safe to consume crab claw meat regardless of the origin of the crab. The consumption of whole crabs including brown meat in the coastal population, however, was calculated to lead to an intake of cadmium above the tolerable weekly intake. In general, brown meat should be consumed parsimoniously and a legal maximum limit for cadmium in brown meat and mixtures of brown meat and white meat should be considered

Same but different: how agency modulates pain perception

Why is analgesic treatment more effective when it is self-administered? Strube et al. compare two possible accounts and show that the effect of agency on perception is linked to a shift in expectation (prior) rather than to reduced likelihood precision, highlighting that agency has a profound impact on the entire perceptual process

Old-Fashioned Pep Rallies to Spotlight Football, Soccer; UD Grad, Bar Code Inventor Returns to Alma Mater; JFK Statue Comes Home in Time for Homecoming; 300 Runners Expected for Homecoming 5k Race

News release announces that two pep rallies will be held during Homecoming Weekend; Paul McEnroe will talk about his work to develop the bar code; The restored JFK statue will be unveiled; The annual Thomas J. Frericks 5K run/walk will be held

Renal amyloidosis revisited: amyloid distribution, dynamics and biochemical type

Background. Renal amyloidosis results from protein misfolding and leads to progressive renal insufficiency. Few data are available concerning the relevance of the histomorphological patterns and the dynamics of the disease process. Methods. Cases of renal amyloidosis in native kidney biopsies (n = 203) were retrospectively evaluated for the pattern of amyloid distribution, the extent of glomerular amyloid deposition and the amount of interstitial fibrosis and tubular atrophy. One hundred and fifty-eight cases were characterized by immunohistochemistry to determine the biochemical amyloid type. Morphological findings were correlated with available clinical data. Results. According to the predominant site of amyloid deposition, 84.6% showed a glomerular, 9.4% a vascular and 6% a tubulointerstitial distribution pattern. Within the glomeruli, amyloid was initially deposited in a focal segmental fashion that became diffuse and global in later stages. Most cases were identified as AL lambda (84/158) or AA (68/158). There was no correlation between the biochemical type and the distribution pattern. Serum creatinine correlated well with interstitial fibrosis and tubular atrophy and proteinuria with the glomerular amyloid load. Conclusions. The relevance of the different distribution patterns is unclear at the moment, but they may be due to the physicochemical properties of the amyloid fibrils in a given patient. This may become important in future anti-fibrillar therapie

Airmass dependence of the Dobson total ozone measurements

For many years the airmass dependence of total ozone measurements at Belsk has been observed to vary noticeably from one day to another. Series of AD wavelength pairs measurements taken out to high airmass were analyzed and compared with the two parameter stray light model presented by Basher. The analysis extended to the series of CD measurements indicates the role of atmospheric attenuation in appearing the airmass dependence. The minor noon decline of total ozone has been observed in the CD measurement series similarly as in those of the AD wavelength pairs. Such errors may seriously affect the accuracy of CD measurements at high latitude stations and the observations derived in winter at middle latitude stations