NetCluster: a Clustering-Based Framework for Internet Tomography

Abstract — In this paper, Internet data collected via passive measurement are analyzed to obtain localization information on nodes by clustering (i.e., grouping together) nodes that exhibit similar network path properties. Since traditional clustering algorithms fail to correctly identify clusters of homogeneous nodes, we propose a novel framework, named “NetCluster”, suited to analyze Internet measurement datasets. We show that the proposed framework correctly analyzes synthetically generated traces. Finally, we apply it to real traces collected at the access link of our campus LAN and discuss the network characteristics as seen at the vantage point. I. INTRODUCTION AND MOTIVATIONS The Internet is a complex distributed system which continues to grow and evolve. The unregulated and heterogeneous structure of the current Internet makes it challenging to obtai

Three mirror glancing incidence system for X-ray telescope

A telescope suitable for soft X-ray astronomical observations consists of a paraboloid section for receiving rays at a grazing angle and a hyperboloid section which receives reflections from the paraboloid at a grazing angle and directs them to a predetermined point of focus. A second hyperboloid section is centrally located from the other two surfaces and positioned to reflect from its outer surface radiation which was not first reflected by the paraboloid. A shutter is included to assist in calibration

Pervasive Displays Research: What's Next?

Reports on the 7th ACM International Symposium on Pervasive Displays that took place from June 6-8 in Munich, Germany

An unconvincing transformation? Michelson's interferential spectroscopy

Albert Abraham Michelson (1852-1931), the American optical physicist best known for his precise determination of the velocity of light and for his experiments concerning aether drift, is less often acknowledged as the creator of new spectroscopic instrumentation and new spectroscopies. He devised a new method of light analysis relying upon his favourite instrument – a particular configuration of optical interferometer – and published investigations of spectral line separation, Doppler-broadening and simple high-resolution spectra (1887-1898). Contemporaries did not pursue his method. Michelson himself discarded the technique by the end of the decade, promoting a new device, the ‘echelon spectroscope’, as a superior instrument. High-resolution spectroscopy was taken up by others at the turn of the century using the echelon, Fabry-Pérot etalon and similar instruments. Michelson’s ‘Light Wave Analysis’ was largely forgotten, but was rediscovered c1950 and developed over the following three decades into a technique rechristened ‘Fourier transform spectroscopy’. This paper presents Michelson’s interferometric work as a continuum of personal interests and historical context as an example of 'research technology' and 'peripheral science'

Neighborhood Typology and Cardiometabolic Pregnancy Outcomes in the Maternal Adiposity Metabolism and Stress Study.

ObjectiveThis study aimed to assess associations between neighborhood typologies classified across multiple neighborhood domains and cardiometabolic pregnancy outcomes and determine variation in effectiveness of a mindfulness-based stress-reduction intervention on outcomes across neighborhood types.MethodsNeighborhoods of participants in the Maternal Adiposity Metabolism and Stress (MAMAS) intervention (n = 208) were classified across dimensions of socioeconomic, food, safety, and service/resource environments using latent class analysis. The study estimated associations between neighborhood type and three cardiometabolic pregnancy outcomes-glucose tolerance (GT) during pregnancy, excessive gestational weight gain, and 6-month postpartum weight retention (PPWR)-using marginal regression models. Interaction between neighborhood type and intervention was assessed.ResultsFive neighborhood types differing across socioeconomic, food, and resource environments were identified. Compared with poor, well-resourced neighborhoods, middle-income neighborhoods with low resources had higher risk of impaired GT (relative risk [RR]: 4.1; 95% confidence Interval [CI]: 1.1, 15.5), and wealthy, well-resourced neighborhoods had higher PPWR (beta: 3.9 kg; 95% CI: 0.3, 7.5). Intervention effectiveness varied across neighborhood type with wealthy, well-resourced and poor, moderately resourced neighborhoods showing improvements in GT scores. PPWR was higher in intervention compared with control groups within wealthy, well-resourced neighborhoods.ConclusionsConsideration of multidimensional neighborhood typologies revealed important nuances in intervention effectiveness on cardiometabolic pregnancy outcomes

Bat response to differing fire severity in mixed-conifer forest California, USA

Wildlife response to natural disturbances such as fire is of conservation concern to managers, policy makers, and scientists, yet information is scant beyond a few well-studied groups (e.g., birds, small mammals). We examined the effects of wildfire severity on bats, a taxon of high conservation concern, at both the stand (<1 ha) and landscape scale in response to the 2002 McNally fire in the Sierra Nevada region of California, USA. One year after fire, we conducted surveys of echolocation activity at 14 survey locations, stratified in riparian and upland habitat, in mixed-conifer forest habitats spanning three levels of burn severity: unburned, moderate, and high. Bat activity in burned areas was either equivalent or higher than in unburned stands for all six phonic groups measured, with four groups having significantly greater activity in at least one burn severity level. Evidence of differentiation between fire severities was observed with some Myotis species having higher levels of activity in stands of high-severity burn. Larger-bodied bats, typically adapted to more open habitat, showed no response to fire. We found differential use of riparian and upland habitats among the phonic groups, yet no interaction of habitat type by fire severity was found. Extent of high-severity fire damage in the landscape had no effect on activity of bats in unburned sites suggesting no landscape effect of fire on foraging site selection and emphasizing stand-scale conditions driving bat activity. Results from this fire in mixed-conifer forests of California suggest that bats are resilient to landscape-scale fire and that some species are preferentially selecting burned areas for foraging, perhaps facilitated by reduced clutter and increased post-fire availability of prey and roost

Let\u27s Observe!

Teaching the non-science major how to teach science is a challenge! No matter what science course is being taught, professors must model good teaching strategies that promote an inquiry approach that incorporates prior knowledge, connections, a social environment, relevance, and time to actively construct new understandings of scientific concepts