387 research outputs found
MEMS Technology Demonstration on Traveler-I
Traveler-I is a flight test platform for advanced micro-electro-mechanical systems (MEMS) devices that is being built at the University of Southern California (USC) and is to be flown aboard the next Scorpius® sub-orbital launch vehicle. Microcosm, Inc. and Scorpius Space Launch Company have initiated a program that currently provides sub-orbital launch opportunities, with the possibility of orbital flights in the future. Flight opportunities such as these allow for short duration missions where new technologies can be rapidly developed and tested in a launch and space environment. Traveler-I allows for low cost flight demonstration and testing of new and innovative MEMS devices such as a Free-Molecule Micro-Resistojet (FMMR) and a Knudsen Compressor. The FMMR is a MEMSbased propulsion system for low impulse bit delivery, which is designed to perform attitude control and primary maneuvers for nanosatellites. The Knudsen Compressor is a MEMS-based vacuum pump that employs the physical principle of thermal transpiration to drive a flow across an aerogel substance. Advances in MEMS capabilities have allowed the construction of micro-scale versions of space sensors such as mass spectrometers, optical spectrometers, and gas chromatographs. These devices require vacuum pumps to provide the necessary environment for their operation. Inexpensive and rapid access to space may eventually lead to low-cost testing, which supports rapid development and redesign so that more mature and reliable technologies can be used in future satellite systems, without the expense of designing, building and operating an entire satellite. In addition, the size of MEMS devices allows for the testing of multiple systems simultaneously. Traveler-I is a good example of how advanced technologies may be tested for low cost while reducing risk and development time for future programs
Socialinių judėjimų vaidmuo formuojant viešąjį klimato kaitos diskursą ir žinojimą
The article is aimed at discussing the role of social movements in shaping the climate change knowledge and public discourse from the perspective of social movement theory, which has been relatively neglected in the scientific literature on climate change and knowledge. The article reviews relevant studies and theories of social movements with special attention to the role of knowledge making in social movements. It discusses the shaping and identity of social movements and relations between social movements and climate change knowledge from the 1970s to the present. The paper traces the emergence of climate change as an issue of public concern within the context of the environmental movements of the 1970s and 1980s. By contrast, paper argues that climate
skepticism was shaped, in significant ways, by the neo-conservative and neo-nationalist movements that grew to political significance in the 1980s and 1990s. The neo-liberal movements of the 1990s and 2000s – albeit providing controversial views, food for public debates and narrowing the discourse to cost-benefit based approaches to climate change - are seen to have helped shaping the recent rise to public attention of climate change as an overarching political problem. In the concluding section, the article discusses how concerns with “climate justice” have emerged as part of a social movement for global justice, and contrasts the different social movements that have affected and influenced the making of climate change knowledge.Straipsnyje gvildenama klimato kaitos diskuro ir žinojimo raida, remiantis socialinių judėjimų teorija, kuri iki šiol menkai taikyta klimato ir tvaraus, darnaus vystymosi tematiką nagrinėjančioje mokslinėje literatūroje. Prieš aptariant sąryšį tarp socialinių judėjimų ir žinojimo apie klimato kaitą, besiformavusį nuo 1970-ųjų iki šiol, straipsnyje apžvelgiami reikšmingi socialinių judėjimų tyrimai ir teorijos, ypatingą dėmesį skiriančios žinojimo formavimuisi socialiniuose judėjimuose. Pirmą kartą klimato kaita, kaip visuomenei aktuali problema, aplinkosauginių judėjimų kontekste iškilo 1970–1980-ųjų laikotarpiu. Tuo tarpu skepticizmas šiais klausimais įvairiais keliais formavosi kaip neokonservatyvizmo bei neonacionalistinio judėjimo sudėtinė dalis, politinę reikšmę įgijusi 1980-1990 m. Neoliberalūs judėjimai 1990-2000-ųjų laikotarpiu interpretuojami kaip tokie, kurie – kvestionuodami radikalias ankstyvojo ekologinio judėjimo nuostatas ir telkdami dėmesį į kaštų-naudos santykį viešojoje politikoje – sukelė diskursyvią prieštarą, kontroversiją ir tuo pačiu padėjo sutelkti pastarųjų metų visuomenės dėmesį į klimato kaitą kaip bendrą politinę problemą. Galiausiai straipsnyje aptariama, kaip “klimato teisingumo” socialinių judėjimų raida susijusi su globalaus socialio teisingumo judėjimų raida. Straipsnyje prienama prie išvados apie tai, kaip skirtingi socialiniai judėjimai sąlygojo klimato kaitos žinių ir diskurso formavimąsi globaliame darnaus, tvaraus vystymosi diskurso kontekste
Spatial scaling properties of coral reef benthic communities
The spatial structure of ecological communities on tropical coral reefs across seascapes and geographies have historically been poorly understood. Here we addressed this for the first time using spatially expansive and thematically resolved benthic community data collected around five uninhabited central Pacific oceanic islands, spanning 6° latitude and 17° longitude. Using towed-diver digital image surveys over ~140 linear km of shallow (8–20 m depth) tropical reef, we highlight the autocorrelated nature of coral reef seascapes. Benthic functional groups and hard coral morphologies displayed significant spatial clustering (positive autocorrelation) up to kilometre-scales around all islands, in some instances dominating entire sections of coastline. The scale and strength of these autocorrelation patterns showed differences across geographies, but patterns were more similar between islands in closer proximity and of a similar size. For example, crustose coralline algae (CCA) were clustered up to scales of 0.3 km at neighbouring Howland and Baker Islands and macroalgae were spatially clustered at scales up to ~3 km at both neighbouring Kingman Reef and Palmyra Atoll. Of all the functional groups, macroalgae had the highest levels of spatial clustering across geographies at the finest resolution of our data (100 m). There were several cases where the upper scale at which benthic community members showed evidence of spatial clustering correlated highly with the upper scales at which concurrent gradients in physical environmental drivers were spatially clustered. These correlations were stronger for surface wave energy than subsurface temperature (regardless of benthic group) and turf algae and CCA had the closest alignments in scale with wave energy across functional groups and geographies. Our findings suggest such physical drivers not only limit or promote the abundance of various benthic competitors on coral reefs, but also play a key role in governing their spatial scaling properties across seascapes
An interactive 3-D application for pain management: Results from a pilot study in spinal cord injury rehabilitation
This is the post-print version of the Article. The official published version can be accessed from the link below - Copyright @ 2012 ElevierResearch on pain following spinal cord injury (SCI) has revealed that patients not only experience several types of pain that could prove to be challenging to address, but also that each individual can interpret such pain in different subjective ways. In this paper we introduce a 3-D system for facilitating the efficient management of pain, and thus, supporting clinicians in overcoming the aforementioned challenges. This system was evaluated by a cohort of 15 SCI patients in a pilot study that took place between July and October 2010. Participants reported their experiences of using the 3-D system in an adapted version of the System Usability Scale (SUS) questionnaire. Statistically significant results were obtained with regards to the usability and efficiency of the 3-D system, with the majority of the patients finding it particularly useful to report their pain. Our findings suggest that the 3-D system can be an efficient tool in the efforts to better manage the pain experience of SCI patients
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