63 research outputs found
Swelling and shrinking kinetics of a lamellar gel phase
No full textWe investigate the swelling and shrinking of L lamellar gel phases composed of surfactant and fatty alcohol after contact with aqueous poly(ethyleneglycol) solutions. The height change Δh(t) is diffusionlike with a swelling coefficient S: Δh=S√t. On increasing polymer concentration, we observe sequentially slower swelling, absence of swelling, and finally shrinking of the lamellar phase. This behavior is summarized in a nonequilibrium diagram and the composition dependence of S quantitatively described by a generic model. We find a diffusion coefficient, the only free parameter, consistent with previous measurements
Integrating SLAM-DUNK and variable rate particle observers for fast multi-hypothesis SLAM
No full textThis electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.Thesis: M. Eng., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2019Cataloged from student-submitted PDF version of thesis.Includes bibliographical references (pages 73-74).In this thesis, the problem of SLAM with some set of prior hypotheses about the map, called Multi-Hypothesis SLAM, was tackled using a combination of an existing landmark-based SLAM algorithm called SLAM-DUNK and a particle filter inspired approach. SLAM-DUNK is a recent Kalman Filter-based algorithm for landmark tracking that scales linearly with the number of landmarks and converges globally to true landmark coordinates, thus far outperforming standard Kalman filter methods such as EKF-SLAM. This was combined with the Hybrid Variable Rate Particle Observer, a particle-filter inspired approach used here for hypothesis discrimination and particularly suited to tracking applications. An algorithm based on combining these two methods was formulated and shown to solve the problem quite successfully, with good resistance to complicating factors such as noise and number of hypotheses. The limitations and peak performance of this algorithm were also investigated by considering the ability of the algorithm to discriminate between very similar hypotheses and the conditions under which the algorithm performed best. Finally, the ability to extend this algorithm to dierent types of hypotheses, including Dense Maps owing to SLAM-DUNK's versatility, was considered and discussed.by Sanchit Bhattacharjee.M. Eng.M.Eng. Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Scienc
Botsende wereldbeelden: Amerika en Europa
No full textThomas von der Dunk argues that the world views of Americans and Europeans are fundamentally different. Now that Barack Obama has been elected the new President of the United States hopes are high that the transatlantic relations, which have strongly deteriorated during the two Bush Administrations will significantly improve. However, the author thinks the differences that have recently emerged between both sides of the Atlantic as far as political views are concerned, are fundamental and persistent, because they are directly linked to a diverging world view. Furthermore, American and European interests have drifted apart since the Berlin Wall collapsed. As opposed to the hope for a 'new beginning' that has emerged among Americans and has caught many Europeans as well, the author points to those same Europeans viewing with scepticism the promises of change from their own politicians. Traditionally, Europeans share the positive image of America as the country of hope for the future. Hence they are somewhat blind to the differences that will persist between both continents, even though the Democrats have taken over power in Washington. Those differences concern the consequences of the deep-rooted aversion to the government, the crucial role of religion, as well as the immigrant origin for the American national consciousness, in particular the direct ideological relation between nation and form of government for the foreign policy of a country that considers it its task to be a role model for the whole of humanity. The American perception of 9/11 as well as the fatal reasoning processes in terms of black and white should be viewed in this context
NASCAR as a Public Good
No full textAbstract This paper looks for evidence that either a NASCAR track or NASCAR-sanctioned event influences the monthly rents on residential units. Data cover individual housing units in more than 140 SMSAs over the period spanning from 1993 until 2005. During this period, several new tracks opened, while some other tracks closed, and numerous races changed venues. These changes enable us to identify the capitalization of costs and benefits to a community from the presence of NASCAR tracks and events into rental values. The evidence is mixed, varying with the treatment of housing units located in or out of central cities of SMSAs, as well as the manner in which missing housing and community characteristics are treated in the analysis. The results are reasonably clear that presence of a track by itself has little effect, especially on housing units outside the central city of an SMSA. Specific types of races largely appear to have no impact, though in some specifications, the central city and non-central city impacts are about equal but have opposite signs. In these cases, the indication is that the NASCAR events affect non-central city rents, but not those in the central city. Overall, we must conclude that our results reject NASCAR as a source of either large benefits or costs to residents of the host community.tourism, economic impact, special events, NASCAR, auto racing
Rock, Paper, Scissors: Game Theory in Everyday Life
No full textThe IgNobel Prize-winning author of How to Dunk a Doughnut draws on the science of game theory to explain how human beings cooperate in everyday life
Angiotensin II induces soluble fms-Like tyrosine kinase-1 release via calcineurin signaling pathway in pregnancy
No full textMaternal endothelial dysfunction in preeclampsia is associated with increased soluble fms-like tyrosine kinase-1 (sFlt-1), a circulating antagonist of vascular endothelial growth factor and placental growth factor. Angiotensin II (Ang II) is a potent vasoconstrictor that increases concomitant with sFlt-1 during pregnancy. Therefore, we speculated that Ang II may promote the expression of sFlt-1 in pregnancy. Here we report that infusion of Ang II significantly increases circulating levels of sFlt-1 in pregnant mice, thereby demonstrating that Ang II is a regulator of sFlt-1 secretion in vivo. Furthermore, Ang II stimulated sFlt-1 production in a dose- and time-dependent manner from human villous explants and cultured trophoblasts but not from endothelial cells, suggesting that trophoblasts are the primary source of sFlt-1 during pregnancy. As expected, Ang II-induced sFlt-1 secretion resulted in the inhibition of endothelial cell migration and in vitro tube formation. In vitro and in vivo studies with losartan, small interfering RNA specific for calcineurin and FK506 demonstrated that Ang II-mediated sFlt-1 release was via Ang II type 1 receptor activation and calcineurin signaling, respectively. These findings reveal a previously unrecognized regulatory role for Ang II on sFlt-1 expression in murine and human pregnancy and suggest that elevated sFlt-1 levels in preeclampsia may be caused by a dysregulation of the local renin/angiotensin system
Virginia and Maryland, United States 1755
No full textMap in multiple sheets. bottom portion missing 2/2023. Relief shown pictorially.; Hand colored.; Prime meridian: Philadelphia and Curratuck Inlet.; "To the Right Honourable, George Dunk Earl of Halifax ..."; Includes distance chart added by "J. Dalrymple, London Jany. ye. 1st. 1755."; Mounted on paper, conserved.Color;approximately 1:650,00
Movement of non-native rainbow trout in an estuary with periodic summer hypoxia
No full textMany present-day aquatic ecosystems are defined by anthropogenic activities such as the introduction of non-native species, habitat loss, and eutrophication. On Prince Edward Island, Canada, non-native rainbow trout (Oncorhynchus mykiss) have established in highly agricultural coastal watersheds. We used acoustic telemetry with continual oxygen and temperature monitoring to explore the relationship between rainbow trout movements, low dissolved oxygen, high temperature, and other environmental parameters in the eutrophic Dunk River estuary. We tested the hypothesis that rainbow trout capitalize on increased productivity from nutrient stimulation but face a trade-off with disturbed water quality. We divided the salinity transition gradient into zones representing the transition from freshwater to seawater and established that temperature and hypoxia increased with salinity. During hypoxic periods, movements decreased, and residence increased in low salinity habitat ( 6 mg L−1, discharge averaging 2 m3 s−1, and temperatures below 23 °C. This study provides insights into the success of rainbow trout in eutrophic estuaries
The difference in ground reaction force between two landing strategies of two dunking styles of basketball players
No full textviii, 67 leaves : ill. ; 28 cm.Purpose of this study was to quantify expected peak ground reaction force differences between one-footed landing and two-footed landing after dunking a basketball. After a pilot study with 3 recreational college basketball players, research subjects were 8 male Division II and III college basketball players. Results were that ground reaction force and impulse values were significantly greater for the two-footed landing vs. one-footed landing after either a one-handed dunk or a two-handed dunk. The author postulates that landing on two feet simultaneously would distribute the force and impulse over both feet, reducing the values on either foot compared with the one-footed landing, and presumably reducing the risk of injury. The literature review concludes that ankle and knee injuries are the two most common injuries to basketball players, and that appropriate landing strategies can reduce the resultant forces
A map of the most inhabited part of Virginia containing the whole province of Maryland : with part of Pensilvania, New Jersey and North Carolina /
No full textScale ca. 1:650,000.Relief shown pictorially.Hand colored.Prime meridian: Philadelphia and Curratuck Inlet."To the Right Honourable, George Dunk Earl of Halifax ... "Includes distance chart added by "J. Dalrymple, London Jany. ye 1st. 1755."LC Maps of North America, 1750-1789, 142
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