Fluid Outflows From Venus Impact Craters: Analysis From Magellan Data

Many impact craters on Venus have unusual outflow features originating in or under the continuous ejecta blankets and continuing downhill into the surrounding terrain. These features clearly resulted from flow of low-viscosity fluids, but the identity of those fluids is not clear. In particular, it should not be assumed a priori that the fluid is an impact melt. A number of candidate processes by which impact events might generate the observed features are considered, and predictions are made concerning the rheological character of flows produced by each mechanism. A sample of outflows was analyzed using Magellan images and a model of unconstrained Bingham plastic flow on inclined planes, leading to estimates of viscosity and yield strength for the flow materials. It is argued that at least two different mechanisms have produced outflows on Venus: an erosive, channel-forming process and a depositional process. The erosive fluid is probably an impact melt, but the depositional fluid may consist of fluidized solid debris, vaporized material, and/or melt

A new test procedure to validate tensile dynamic mechanical properties of sheet metals and alloys in automotive crash applications

A thin walled open channel beam subjected to a 3-point bend and constant velocity boundary condition is investigated to establish its potential to validate material performance for automotive crash applications. Specifically quantitative validation of material data determined from high speed tensile testing and qualitative validation of material resistance to fracture in crash components. Open channel beams are fabricated from structural grade sheet steel and aluminium alloy and tested at quasi-static and higher speeds up to 10 m/s and in all cases, deformation develops a plastic hinge. This paper describes development of the validation test procedure, specifically design of specimen, system of measurement and boundary conditions using numerical and experimental techniques. The new test procedure will increase confidence in materials modelling and reduce the risk to introduce new advanced high strength materials into automotive crash structures

Measurement of Effective Temperatures in an Aging Colloidal Glass

We study the thermal fluctuations of an optically confined probe particle, suspended in an aging colloidal suspension, as the suspension transforms from a viscous liquid into an elastic glass. The micron-sized bead forms a harmonic oscillator. By monitoring the equal-time fluctuations of the tracer, at two different laser powers, we determine the temperature of the oscillator, $T_{\text{o}}$. In the ergodic liquid the temperatures of the oscillator and its environment are equal while, in contrast, in a nonequilibrium glassy phase we find that $T_{\text{o}}$ substantially exceeds the bath temperature.Comment: 4 pages (minor changes, accepted Phys. Rev. Lett.

Bad News for Chordal Partitions

Reed and Seymour [1998] asked whether every graph has a partition into induced connected non-empty bipartite subgraphs such that the quotient graph is chordal. If true, this would have significant ramifications for Hadwiger's Conjecture. We prove that the answer is `no'. In fact, we show that the answer is still `no' for several relaxations of the question

Making Public Media Personal: Nostalgia and Reminiscence in the Office

In this paper we explore the notion of creating personally evocative collections of content from publicly available material. Compared to the personal media that we look at, reminisce over, or personalise our offices with, public media offers the potential for a different type of nostalgia, signifiers of an era such as entertainment, products, or fashions. We focus on an office environment, where the use of filtered public media may mitigate concerns over protecting privacy and disclosing too much of one's identity, while keeping the existing benefits of office personalisation in terms of reminiscence, improving mood, and developing identity. After preliminary explorations of content and form, we developed a two-screen ambient display that cycled through 500 images automatically retrieved based on four simple user questions. We ran a two-week trial of the display with six users. We present qualitative results of the trial from which we see that it is possible to bring the delight associated with personal content into the workplace, while being mindful of issues of appropriateness and privacy. Images of locations from childhood were particularly evocative for all participants, while simple objects such as stickers, music, or boardgames were more varied across participants. We discuss a number of avenues for future work in the workplace and beyond: improving the chance of an evocative moment, capturing the mundane, and the crowdsourcing of nostalgia

Gait characteristics of subjects with chronic fatigue syndrome and controls at self-selected and matched velocities

Background: Gait abnormalities have been reported in individuals with Chronic Fatigue Syndrome (CFS) however no studies exist to date investigating the kinematics of individuals with CFS in over-ground gait. The aim of this study was to compare the over-ground gait pattern (sagittal kinematics and temporal and spatial) of individuals with CFS and control subjects at their self-selected and at matched velocities. Methods: Twelve individuals with CFS and 12 matched controls participated in the study. Each subject walked along a 7.2 m walkway three times at each of three velocities: self-selected, relatively slow (0.45 ms-1) and a relatively fast (1.34 ms-1). A motion analysis system was used to investigate the sagittal plane joint kinematics and temporal spatial parameters of gait. Results: At self-selected velocity there were significant differences between the two groups for all the temporal and spatial parameters measured, including gait velocity (P = 0.002). For the kinematic variables the significant differences were related to both ankles during swing and the right ankle during stance. At the relatively slower velocity the kinematic differences were replicated. However, the step distances decreased in the CFS population for the temporal and spatial parameters. When the gait pattern of the individuals with CFS at the relatively fast walking velocity (1.30 ± 0.24 ms-1) was compared to the control subjects at their self-selected velocity (1.32 ± 0.15 ms-1) the gait pattern of the two groups was very similar, with the exception of both ankles during swing. Conclusion: The self-selected gait velocity and/or pattern of individuals with CFS may be used to monitor the disease process or evaluate therapeutic intervention. These differences may be a reflection of the relatively low self-selected gait velocity of individuals with CFS rather than a manifestation of the condition itself