Space Station Rapid Sample Return Revisited

Rapid feedback of experiment results helps investigators to fine tune experiments, shorten experiment cycle times, and reduce development costs for new products. A rapid sample return (RSR) system was studied early in the Phase B Space Station Preliminary Design effort as a means of providing rapid feedback to increase station experimental productivity and reduce mission costs. However sufficient justification for baselining a RSR concept was not found. RSR was deemed nonessential because the Space Station would be serviced by a NSTS flight every 45 days and the design included thorough onboard analytical capabilities. Efforts at cost reduction have since reduced habitable station volume by 50%, combining separate life science and materials science modules into a single U.S. Laboratory (USL) module. Volume allocated for USL analytical instrumentation was reduced as a result. This decrease in onboard instrumentation has since been followed by a substantial reduction of NSTS station support flights

High-quality multi-GeV electron bunches via cyclotron autoresonance

Autoresonance laser acceleration of electrons is theoretically investigated using circularly polarized focused Gaussian pulses. Many-particle simulations demonstrate feasibility of creating over 10-GeV electron bunches of ultra-high quality (relative energy spread of order 10^-4), suitable for fundamental high-energy particle physics research. The laser peak intensities and axial magnetic field strengths required are up to about 10^18 W/cm^2 (peak power ~10 PW) and 60 T, respectively. Gains exceeding 100 GeV are shown to be possible when weakly focused pulses from a 200-PW laser facility are used

Dense monoenergetic proton beams from chirped laser-plasma interaction

Interaction of a frequency-chirped laser pulse with single protons and a hydrogen plasma cell is studied analytically and by means of particle-in-cell simulations, respectively. Feasibility of generating ultra-intense (10^7 particles per bunch) and phase-space collimated beams of protons (energy spread of about 1 %) is demonstrated. Phase synchronization of the protons and the laser field, guaranteed by the appropriate chirping of the laser pulse, allows the particles to gain sufficient kinetic energy (around 250 MeV) required for such applications as hadron cancer therapy, from state-of-the-art laser systems of intensities of the order of 10^21 W/cm^2.Comment: 5 pages, 4 figure

Comparison of ecosystem processes in a woodland and prairie pond with different hydroperiods

Shallow lakes and ponds constitute a significant number of water bodies worldwide. Many are heterotrophic, indicating that they are likely net contributors to global carbon cycling. Climate change is likely to have important impacts on these waterbodies. In this study, we examined two small Minnesota ponds; a permanent woodland pond and a temporary prairie pond. The woodland pond had lower levels of phosphorus and phytoplankton than the prairie pond. Using the open water oxygen method, we found the prairie pond typically had a higher level of gross primary production (GPP) and respiration (R) than the woodland pond, although the differences between the ponds varied with season. Despite the differences in GPP and R between the ponds the net ecosystem production was similar with both being heterotrophic. Since abundant small ponds may play an important role in carbon cycling and are likely to undergo changes in temperature and hydroperiod associated with climate change, understanding pond metabolism is critical in predicting impacts and designing management schemes to mitigate changes

Intense high-quality medical proton beams via laser fields

During the past decade, the interaction of high-intensity lasers with solid targets has attracted much interest, regarding its potential in accelerating charged particles. In spite of tremendous progress in laser-plasma based acceleration, it is still not clear which particle beam quality will be accessible within the upcoming multi petawatt (1 PW = 10$^{15}$ W) laser generation. Here, we show with simulations based on the coupled relativistic equations of motion that protons stemming from laser-plasma processes can be efficiently post-accelerated using crossed laser beams focused to spot radii of a few laser wavelengths. We demonstrate that the crossed beams produce monoenergetic accelerated protons with kinetic energies $> 200$ MeV, small energy spreads ($\approx$ 1$$) and high densities as required for hadron cancer therapy. To our knowledge, this is the first scheme allowing for this important application based on an all-optical set-up.Comment: 14 pages, 3 figures, 1 tabl

Learning a Factor Model via Regularized PCA

We consider the problem of learning a linear factor model. We propose a regularized form of principal component analysis (PCA) and demonstrate through experiments with synthetic and real data the superiority of resulting estimates to those produced by pre-existing factor analysis approaches. We also establish theoretical results that explain how our algorithm corrects the biases induced by conventional approaches. An important feature of our algorithm is that its computational requirements are similar to those of PCA, which enjoys wide use in large part due to its efficiency

Advanced cognitive networked radar surveillance

The concept of a traditional monostatic radar with co-located transmit and receive antennas naturally imposes performance limits that can adversely impact applications. Using a multiplicity of transmit and receive antennas and exploiting spatial diversity provides additional degrees of design freedom that can help overcome such limitations. Further, when coupled with cognitive signal processing, such advanced systems offer significant improvement in performance over their monostatic counterparts. This will also likely lead to new applications for radar sensing. In this paper we explore the fundamentals of multistatic network radar highlighting both potential and constraints whilst identifying future research needs and applications. Initial experimental results are presented for a 2-node networked staring radar

Invisible Belfast:Flat ontologies and remediation of the post-conflict city

[in]visible Belfast was a research-driven indie alternate reality game (ARG) that ran for 6 weeks during the spring of 2011 in Belfast and was subsequently adapted, 5 years later into a fictional documentary for BBC Radio 4. The ARG is a participatory and dispersed narrative, which the audience play through. The text expands outward across both physical and digital platforms to create a mystery for the players using everyday platforms. The ARG is a product of media convergence and at its heart transmedial, defined by its complexity and modes of participation. The fictional radio documentary which remediated the ARG into a more simple linear structure, but possibly a more complex narrative form, retells parts of the story for new audiences. The premise of [in]visible belfast – the game and later the documentary – is itself an adaptation of writer Ciaran Carson’s novel The Star Factory (1997): a postmodern adventure through the complex psychogeography of Belfast. A trail through the labyrinthine text, which paints the history of Belfast in poetic prose. This article will map the concept’s journey from novel to game to radio, contextualising its development within its political and urban landscape and charting the remediation of the narratives as they fold out across multiple media and complex story arches. The article will draw together ideas from previous publications on ARG, transmediality and complex textualities from the authors and reflect on the textual trajectories that the remediation of the narrative has taken from the original book, through the ARG, into the radio documentary. Building upon recent approaches from environmental philosopher Tim Morton and games theorist Ian Bogost, the authors argue that Belfast’s history propels medial adaptations of a particular kind, characterised by a ‘flat’ ontology of space and time and a sort of diffuse and dark urban experience for designers/producers and players/listeners

Human and Non-Human Primate Intestinal FcRn Expression and Immunoglobulin G Transcytosis

PURPOSE: To evaluate transcytosis of immunoglobulin G (IgG) by the neonatal Fc receptor (FcRn) in adult primate intestine to determine whether this is a means for oral delivery of monoclonal antibodies (mAbs). METHODS: Relative regional expression of FcRn and localization in human intestinal mucosa by RT-PCR, ELISA & immunohistochemistry. Transcytosis of full-length mAbs (sandwich ELISA-based detection) across human intestinal segments mounted in Ussing-type chambers, human intestinal (caco-2) cell monolayers grown in transwells, and serum levels after regional intestinal delivery in isoflurane-anesthetized cynomolgus monkeys. RESULTS: In human intestine, there was an increasing proximal-distal gradient of mucosal FcRn mRNA and protein expression. In cynomolgus, serum mAb levels were greater after ileum-proximal colon infusion than after administration to stomach or proximal small intestine (1–5 mg/kg). Serum levels of wild-type mAb dosed into ileum/proximal colon (2 mg/kg) were 124 ± 104 ng/ml (n = 3) compared to 48 ± 48 ng/ml (n = 2) after a non-FcRn binding variant. In vitro, mAb transcytosis in polarized caco-2 cell monolayers and was not enhanced by increased apical cell surface IgG binding to FcRn. An unexpected finding in primate small intestine, was intense FcRn expression in enteroendocrine cells (chromagranin A, GLP-1 and GLP-2 containing). CONCLUSIONS: In adult primates, FcRn is expressed more highly in distal intestinal epithelial cells. However, mAb delivery to that region results in low serum levels, in part because apical surface FcRn binding does not influence mAb transcytosis. High FcRn expression in enteroendocrine cells could provide a novel means to target mAbs for metabolic diseases after systemic administration