cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
Scintillation of PSR B1508+55 -- the view from a 10,000-km baseline
Creators: name: Marthi, V. R.
name: Simard, D.
name: Main, R. A.
name: Pen, U. -L.
name: van Kerkwijk, M. H.
name: Vanderlinde, K.
name: Gupta, Y.
name: Roberts, C.
name: Quine, B. M.
Publisher: name: arXiv
Year: 2020
Subjects: subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: FOS: Physical sciences

description: We report on the simultaneous Giant Metrewave Radio Telescope (GMRT) and Algonquin Radio Observatory (ARO) observations at 550-750 MHz of the scintillation of PSR B1508+55, resulting in a $\sim$10,000-km baseline. This regime of measurement lies between the shorter few 100-1000~km baselines of earlier multi-station observations and the much longer earth-space baselines. We measure a scintillation cross-correlation coefficient of $0.22$, offset from zero time lag due to a $\sim 45$~s traversal time of the scintillation pattern. The scintillation time of 135~s is $3\times$ longer, ruling out isotropic as well as strictly 1D scattering. Hence, the low cross-correlation coefficient is indicative of highly anisotropic but 2D scattering. The common scintillation detected on the baseline is confined to low delays of $\lesssim 1 μ$s, suggesting that this correlation may not be associated with the parabolic scintillation arc detected at the GMRT. Detection of pulsed echoes and their direct imaging with the Low Frequency Array (LOFAR) by a different group enable them to measure a distance of 125~pc to the screen causing these echoes. These previous measurements, alongside our observations, lead us to propose that there are at least two scattering screens: the closer 125 pc screen causing the scintillation arc detected at GMRT, and a screen further beyond causing the scintillation detected on the GMRT-ARO baseline. We advance the hypothesis that the 125-pc screen partially resolves the speckle images on the screen beyond leading to loss of coherence in the scintillation dynamic spectrum, to explain the low cross-correlation coefficient.
description: 10 pages, 8 figures, accepted for publication in MNRAS
A COMPARISON OF MINNESOTA'S FARM BUSINESS MANAGEMENT ASSOCIATION MEMBERS AND THE USDA'S FARM COSTS AND RETURNS SURVEY
Creators: name: Andersson, Hans
name: Olson, Kent D.
name: Andersson, Hans
name: Olson, Kent D.
Publisher: name: Unknown
Year: 1992
Subjects: Farm Management

description: Many states have farm record associations which collect individual farm data. This data are used for research, extension, and teaching purposes. However, since membership in the associations is voluntary, the question arises whether the members are representative of the population of all farmers in that area. This study compares farm record data collected through the Southeastern and Southwestern Minnesota Farm Business Management Associations (FBMA) and data obtained through the USDA's Farm Costs and Returns Survey (FCRS). Both data sets were for 1987. By design, the FCRS survey is not subject to the self-selection bias that may occur in the FBMA data. The objectives of this study are to: (1) determine which farm characteristics are statistically the same in the FBMA and FCRS data, and (2) determine the farm size ranges in which FBMA farms are statistically representative of FCRS farms'. FBMA farms were not representative of all farms in their area. FBMA farms do not include small operations. Major differences exist in total tillable acreage, rented land and livestock production, especially hogs. These combined differences result in a substantial difference in net farm income between the two farm categories. However, the FBMA farms reflect FCRS farms' solvency conditions relatively well. FBMA farms were more similar to farms with sales exceeding $60,000 per year but differences still existed. Total acreage, total sales (especially sales of hogs), total expenses, and net farm income were significantly (p.10), the economic performance of the FBMA farms appears to be better than FCRS farms even in larger sizes. On the basis of these findings, the FBMA data cannot be used to represent all farms or even all commercial farms. It does appear that FBMA farms can be used to represent larger farms with livestock. Thus, the FBMA data is not well-suited for estimation of economic relationships to be used in aggregate economic analyses of the agricultural sector.
On an extension of the generalized BGW tau-function
Creators: name: Yang, Di
name: Zhou, Chunhui
Publisher: name: arXiv
Year: 2020
Subjects: subject: Mathematical Physics (math-ph)
subject: Algebraic Geometry (math.AG)
subject: Exactly Solvable and Integrable Systems (nlin.SI)
subject: FOS: Physical sciences
subject: FOS: Mathematics

description: For an arbitrary solution to the Burgers--KdV hierarchy, we define the tau-tuple $(τ_1,τ_2)$ of the solution. We show that the product $τ_1τ_2$ admits Buryak's residue formula. Therefore, according to Alexandrov's theorem, $τ_1τ_2$ is a tau-function of the KP hierarchy. We then derive a formula for the affine coordinates for the point of the Sato Grassmannian corresponding to the tau-function $τ_1τ_2$ explicitly in terms of those for $τ_1$. Applications to the analogous open extension of the generalized BGW tau-function and to the open partition function are given.
description: Minor changes: improved presentations; corrected typos; added references. 21pages
LCS Graph Kernel Based on Wasserstein Distance in Longest Common Subsequence Metric Space
Creators: name: Huang, Jianming
name: Fang, Zhongxi
name: Kasai, Hiroyuki
Publisher: name: arXiv
Year: 2020
Subjects: subject: Machine Learning (cs.LG)
subject: Artificial Intelligence (cs.AI)
subject: Data Structures and Algorithms (cs.DS)
subject: Machine Learning (stat.ML)
subject: FOS: Computer and information sciences

description: For graph learning tasks, many existing methods utilize a message-passing mechanism where vertex features are updated iteratively by aggregation of neighbor information. This strategy provides an efficient means for graph features extraction, but obtained features after many iterations might contain too much information from other vertices, and tend to be similar to each other. This makes their representations less expressive. Learning graphs using paths, on the other hand, can be less adversely affected by this problem because it does not involve all vertex neighbors. However, most of them can only compare paths with the same length, which might engender information loss. To resolve this difficulty, we propose a new Graph Kernel based on a Longest Common Subsequence (LCS) similarity. Moreover, we found that the widely-used R-convolution framework is unsuitable for path-based Graph Kernel because a huge number of comparisons between dissimilar paths might deteriorate graph distances calculation. Therefore, we propose a novel metric space by exploiting the proposed LCS-based similarity, and compute a new Wasserstein-based graph distance in this metric space, which emphasizes more the comparison between similar paths. Furthermore, to reduce the computational cost, we propose an adjacent point merging operation to sparsify point clouds in the metric space.
[Brev til DKNVS]
Creators: name: Erlandsen, Andreas
name: Det Kongelige Norske Videnskabers Selskab (DKNVS)
Publisher: name: Unknown
Year: 1840

description: Ønsker å få noen bøker av VS til Sparbu prestegjelds almueboksamling
description: Se Adresseavisen nr. 143, 1840. Polydoc nr. 1: 2425. Polydoc nr. 2: 1849.
Making meaning in totemland: investigating a Vancouver commission
Creators: name: Phillips, Kimberly Jean
Publisher: name: University of British Columbia
Year: 2009

description: In the years immediately following World War II in Vancouver, native Northwest Coast images and objects were frequently made visible in the public spaces of the city, claimed and exchanged physically and symbolically in events involving both aboriginal and non-native participants. Like the political and social relations surrounding them, the meaning and purpose of these objects and images was, arguably, pliable and constantly shifting. The Totemland Pole, commissioned in 1950 by Vancouver's fledgling Totemland Society, and designed by local Kwakwaka'wakw carver Ellen Neel, was one such object-as-symbol. Numerous individuals and communities, aboriginal as well as non-native, were implicated in the object's production. Following anthropologist Anthony Cohen's work on social symbols in The Symbolic Construction of Community, I argue that while the symbol itself was held in common, its meaning varied with its participants' unique orientations to it. The differently motivated parties, specifically the work's creator, Ellen Neel, and its commissioners, the Totemland Society, attributed divergent meaning to the Totemland Pole simultaneously. As Cohen suggests, I propose that this difference did not lead to argument. Rather it was the form of the Totemland Pole itself, its impreciseness or "malleability," within the particular socio-political climate of its production, which enabled these divergent meanings to co-exist. In order to investigate ways in which the Totemland Pole was understood simultaneously as symbolically meaningful, this project attempts to map out the subject positions of and relations of power between Ellen Neel and the members of the Totemland Society, in relation to the particulars of the local historical moment. The forgotten details of the Totemland Commission and the lack of a legitimizing discourse of Neel's production, both fuelled by the gendered, class and race inflected politics of knowledge construction, have necessitated that the concept of absence be fundamental to my project. I have therefore approached the Totemland Commission from a number of surrounding institutional and social discourses, which form trajectories I see as intersecting at the site of the Totemland Pole. Any one of these trajectories may have been taken as the singular approach for the investigation of such an object. However, I wish to deny the autonomy normally granted these discursive fields, emphasizing instead the ways they are interdependent and may operate in tandem to enrich our understanding of an object which was the result of, and relevant to, shared histories.
Regimes of Stability and Scaling Relations for the Removal Time in the Asteroid Belt: A Simple Kinetic Model and Numerical Tests
Creators: name: Cubrovic, Mihailo
Publisher: name: arXiv
Year: 2005
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: We report on our theoretical and numerical results concerning the transport mechanisms in the asteroid belt. We first derive a simple kinetic model of chaotic diffusion and show how it gives rise to some simple correlations (but not laws) between the removal time (the time for an asteroid to experience a qualitative change of dynamical behavior and enter a wide chaotic zone) and the Lyapunov time. The correlations are shown to arise in two different regimes, characterized by exponential and power-law scalings. We also show how is the so-called "stable chaos" (exponential regime) related to anomalous diffusion. Finally, we check our results numerically and discuss their possible applications in analyzing the motion of particular asteroids.
description: 8 pages, 4 figures; to appear in Proceedings of IAU Colloquium 197: Dynamics of Populations of Planetary Systems
Lattice Collective Modes from a Continuum Model of Magic-Angle Twisted Bilayer Graphene
Creators: name: Kumar, Ajesh
name: Xie, Ming
name: MacDonald, A. H.
Publisher: name: arXiv
Year: 2020
Subjects: subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: FOS: Physical sciences

description: We show that the insulating states of magic-angle twisted bilayer graphene support a series of collective modes corresponding to local particle-hole excitations on triangular lattice sites. Our theory is based on a continuum model of the magic angle flat bands. When the system is insulating at moiré band filling $ν=-3$, our calculations show that the ground state supports seven low-energy modes that lie well below the charge gap throughout the moiré Brillouin zone, one of which couples strongly to THz photons. The low-energy collective modes are faithfully described by a model with a local $SU(8)$ degree of freedom in each moiré unit cell that we identify as the direct product of spin, valley, and an orbital pseudospin. Apart from spin and valley-wave modes, the collective mode spectrum includes a low-energy intra-flavor exciton mode associated with transitions between flat valence and conduction band orbitals.
description: 6+3 pages, 4 figures. v2 adds optical conductivity calculation
Thermodynamics of Trapped Photon Gases at Dimensional Crossover from 2D to 1D
Creators: name: Stein, Enrico
name: Pelster, Axel
Publisher: name: arXiv
Year: 2020
Subjects: subject: Quantum Gases (cond-mat.quant-gas)
subject: FOS: Physical sciences

description: Photon Bose-Einstein condensates are characterised by a quite weak interaction, so they behave nearly as an ideal Bose gas. Moreover, since the current experiments are conducted in a microcavity, the longitudinal motion is frozen out and the photon gas represents effectively a two-dimensional trapped gas of massive bosons. In this paper we focus on a harmonically confined ideal Bose gas in two dimensions, where the anisotropy of the confinement allows for a dimensional crossover. If the confinement in one direction is strong enough so that this squeezed direction is frozen out, then only one degree of freedom survives and the system can be considered to be quasi-one dimensional. In view of an experimental set-up we work out analytically the thermodynamic properties for such a system with a finite number of photons. In particular, we focus on examining the dimensional information which is contained in the respective thermodynamic quantities.
description: 24 pages, 8 figures, submission to New Journal of Physics
Water-Sensitive Design for Climate Resilience: Grounded Lessons from Cape Town
Creators: name: Sanya, Tom
name: Shefer, Donna
Publisher: name: figshare
Year: 2024
Subjects: classificationCode: 330401
subject: Community planning
classificationCode: 330404
subject: Land use and environmental planning
classificationCode: 330405
subject: Public participation and community engagement
classificationCode: 330411
subject: Urban design
classificationCode: 330314
subject: Sustainable design
classificationCode: 410401
subject: Conservation and biodiversity
classificationCode: 410203
subject: Ecosystem function
classificationCode: 410206
subject: Landscape ecology

description: Water Sensitive Design (WSD) has been around in some form at least since the early 1960s. A leading contribution to the field was Australia’s proposal for a transition framework for Water Sensitive Cities. This transition framework has been criticized as not taking full account of the unique challenges experienced in cities in the Global South. These challenges include poverty, governance problems, and resource constraints. These issues converge in Cape Town where they are amplified by entrenched redundant inequality arising from historic separate development during the apartheid era. South Africa’s new post-liberal constitution is founded on principles of social justice, basic human rights, and sustainable development. In the context of enduring water stress, episodic but prolonged droughts and climate change, there are efforts in academia, government, and practice to place South Africa urban areas on the trajectory to becoming water-sensitive cities. This contribution highlights the challenges, proposals, and practices in the highly unequal and contested City of Cape Town (CCT).
FUTURE OF MINNESOTA ANIMAL INDUSTRY: ITS STRUCTURE, PROFITABILITY AND SIZE
Creators: name: Hasbargen, Paul R.
name: Hasbargen, Paul R.
Publisher: name: Unknown
Year: 1980
Subjects: Livestock Production/Industries

description: The purpose of this paper is to suggest some probable changes in the production sector of Minnesota's red meat industry during the eighties. To do this, it first reviews the past trends in hog production and cattle feeding and then considers how these trends might be influenced by some of the major economic and political factors that are evident at this time. Trends and future changes will be discussed with respect to three important industry characteristics--structure (size and number of firms), profitability and locational shifts.
Reconnection at the Heliopause
Creators: name: Nickeler, Dieter H.
name: Fahr, Hans-Joerg
Publisher: name: arXiv
Year: 2005
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: In this MHD-model of the heliosphere, we assume a Parker-type flow, and a Parker-type spiral magnetic field, which is extrapolated further downstream from the termination shock to the heliopause. We raise the question whether the heliopause nose region may be leaky with respect to fields and plasmas due to nonideal plasma dynamics, implying a breakdown of the magnetic barrier. We analyse some simple scenarios to find reconnection rates and circumstances, under which the heliosphere can be an "open" or a "closed" magnetosphere. We do not pretend to offer a complete solution for the heliosphere, on the basis of nonideal MHD theory, but present a prescription to find such a solution on the basis of potential fields including the knowledge of neutral points. As an example we imitate the Parker spiral as a monopole with a superposition of homogeneous asymptotical boundary conditions. We use this toy model for x < -R where R = 100 AU is the distance of the termination shock to describe the situation in the nose region of the heliopause.
description: 12 pages, 3 figures, Advances in Space Research (in press)
Reporting on Bratislava Social Innovation Think Tank (SITT) workshop "Shaping social innovation for marginalized rural areas"
Creators: name: SIMRA Social Innovation Think Thank
Publisher: name: Zenodo
Year: 2016

description: The first workshop of the Social Innovation Think Tank (SITT) on 26-28th October, 2016 in Bratislava (Slovakia) brought together core project partners with the Scientific Advisory and Stakeholder Involvement Boards of SIMRA and discussed multi-faceted and complex challenges that our rural areas face. Common difficulties, such as transport, housing, ageing population, connectivity and regulations link up with global issues of climate change, sustainability, and energy and food security, that calling for immediate solutions, were considered in several rounds of stakeholder consultations. By engaging with stakeholders since the very beginning of project scientists wish to create a transparent and open-ended approach to problem framing. The workshop is therefore considered as an important starting point of the co-construction of SIMRA knowledge with stakeholders. Thanks to the intense three months’ preparation of the stakeholder consultations´ content organised under the Task 2.3 of WP2 and supervised by Tatiana Kluvankova (IFE SAS), project coordinator Maria Nijnik and David Miller (JAMES HUTTON) and thanks to the active work and communication with the most of WP leaders through several skype meetings, workshop achieved the expected and planned results. However, it would not have been possible without active engagement of SITT members from the very beginning of the preparation
 period. SITT members were suggested by project partners and cordially invited by project coordinator Maria Nijnik to attend this event as well as to contribute to the project delivery. From 35 stakeholders addressed by sending invitation letter through email 20 came to the first workshop. To open the fruitful debate with SITT members about their perception and understanding of social innovations at the first meeting, Veronika Gezik (IFE SAS) conducted a short introductory survey through survey monkey (online research survey tool) from June to September 2016. Questions and detailed responses of the survey can be found in annex B. Smooth running of the workshop was ensured thanks to Stanislava Brnkalakova (IFE SAS) and the team of PhD students and other colleagues from SPECTRA – Centre excellence– joint research centre of the Institute of Forest Ecology Slovak Academy of Sciences, Slovak University of Technology and Comenius University who served as local host of the event.
New optical polarization measurements of quasi-stellar objects. The data
Creators: name: Sluse, D.
name: Hutsemekers, D.
name: Lamy, H.
name: Cabanac, R.
name: Quintana, H.
Publisher: name: arXiv
Year: 2005
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: New linear polarization measurements (mainly in the V band) are presented for 203 quasi-stellar objects (QSOs). The sample is made up of 94 QSOs located in the North Galactic Pole (NGP) region and of 109 QSOs in the South Galactic Pole (SGP) region. First time measurements have been obtained for 184 QSOs. Among them, 109 known radio-emitters, 42 known Broad Absorption Line (BAL) QSOs, and 1 gravitationally lensed quasi-stellar object. We found high polarization levels (p > 3%) for 12 QSOs, including the BAL QSO SDSS J1409+0048. For 10 objects, measurements obtained at different epochs do exist. Two of them show evidence for variability: the highly polarized BL Lac candidate PKS 1216-010 and the radio source PKS 1222+037
description: Published in A&A (2005; 433, 757). 12 pages, 5 figures. Table 4 is ALSO available in electronic form at CDS
Backreaction of Schwinger pair creation in massive QED$_2$
Creators: name: Gold, Gregory
name: McGady, David A.
name: Patil, Subodh P.
name: Vardanyan, Valeri
Publisher: name: arXiv
Year: 2020
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: Particle-antiparticle pairs can be produced by background electric fields via the Schwinger mechanism provided they are unconfined. If, as in QED in (3+1)-$d$ these particles are massive, the particle production rate is exponentially suppressed below a threshold field strength. Above this threshold, the energy for pair creation must come from the electric field itself which ought to eventually relax to the threshold strength. Calculating this relaxation in a self-consistent manner, however, is difficult. Chu and Vachaspati addressed this problem in the context of capacitor discharge in massless QED$_2$ [1] by utilizing bosonization in two-dimensions. When the bare fermions are massless, the dual bosonized theory is free and capacitor discharge can be analyzed exactly [1], however, special care is required in its interpretation given that the theory exhibits confinement. In this paper we reinterpret the findings of [1], where the capacitors Schwinger-discharge via electrically neutral dipolar meson-production, and generalize this to the case where the fermions have bare masses. Crucially, we note that when the initial charge of the capacitor is large compared to the charge of the fermions, $Q \gg e$, the classical equation of motion for the bosonized model accurately characterizes the dynamics of discharge. For massless QED$_2$, we find that the discharge is suppressed below a critical plate separation that is commensurate with the length scale associated with the meson dipole moment. For massive QED$_2$, we find in addition, a mass threshold familiar from (3+1)-$d$, and show the electric field relaxes to a final steady state with a magnitude proportional to the initial charge. We discuss the wider implications of our findings and identify challenges in extending this treatment to higher dimensions.
description: 21 pages, 2 figures; several additional references and enhanced discussion. Matches JHEP version
Semiquantum versus semiclassical mechanics for simple nonlinear systems
Creators: name: Bracken, A. J.
name: Wood, J. G.
Publisher: name: arXiv
Year: 2005
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: Quantum mechanics has been formulated in phase space, with the Wigner function as the representative of the quantum density operator, and classical mechanics has been formulated in Hilbert space, with the Groenewold operator as the representative of the classical Liouville density function. Semiclassical approximations to the quantum evolution of the Wigner function have been defined, enabling the quantum evolution to be approached from a classical starting point. Now analogous semiquantum approximations to the classical evolution of the Groenewold operator are defined, enabling the classical evolution to be approached from a quantum starting point. Simple nonlinear systems with one degree of freedom are considered, whose Hamiltonians are polynomials in the Hamiltonian of the simple harmonic oscillator. The behaviour of expectation values of simple observables and of eigenvalues of the Groenewold operator, are calculated numerically and compared for the various semiclassical and semiquantum approximations.
description: Latex2e file. 27 pages, 7 figures. To appear in Phys. Rev. A
Approximately half of the roots of a random Littlewood polynomial are inside the disk
Creators: name: Yakir, Oren
Publisher: name: arXiv
Year: 2020
Subjects: subject: Complex Variables (math.CV)
subject: Probability (math.PR)
subject: FOS: Mathematics

description: We prove that for large $n$, all but $o(2^{n})$ polynomials of the form $P(z) = \sum_{k=0}^{n-1}\pm z^k$ have $n/2 + o(n)$ roots inside the unit disk. This solves a problem from Hayman's book 'Research Problems in Function Theory' (1967).
description: 14 pages
Understanding social innovation for the well-being of rural communities: a preliminary theoretical framework Forum Carpaticum 2018
Creators: name: Kluvankova Tatiana
name: Spacek Martin
name: Brnkalakova Stanislava
name: Ninjik Maria
name: Miller David
name: Valero Diana
name: Gezik Veronika
Publisher: name: Zenodo
Year: 2018

description: The debate on social innovation has rapidly expanded over the last decade. There are considerable expectations of the potential of social innovation for addressing urgent societal challenges in rural communities living in mountain regions. Forests provide a long list of benefits to people and are vital to communities. Sustainable use of forest ecosystem services can provide a substantial contribution to the wellbeing of those communities. In spite of the importance of forest in climate change mitigation highlighted since Rio Earth Summit in 1992, potential of rural communities living in mountain regions has been overlooked in a long term. We follow approach developed in the Horizon2020 project SIMRA (Social Innovation in Marginalised Rural Areas) and explore social innovation in rural communities as “reconfiguration of social practices, in response to societal challenges, which seeks to enhance outcomes on societal well-being and necessarily includes the engagement of civil society actors”. Informed by innovation theory the principal concern of the paper is to determine the types of SIs, which are likely to occur in marginalized rural areas (MRAs), and what can be done to enhance the innovation potential across different types of MRAs. Emergence of social innovations is seen as the collective action, which is comforted or distracted by its surroundings and societal challenges that are affecting dynamics of changes. A key questions to be addressed are: Why communities in some MRAs respond to societal problems? How to integrate experience and local knowledge on forest ecosystem services, selforganization and shared responsibility into the forest governance to enhance wellbeing? In particular the aim is to i) identify the patterns that enable and constrain (lock-ins, path-dependencies) efforts for social innovations in rural communities living in mountain regions to emerge, nurture and develop, ii) present framework for understanding relationships, variables and trajectories of SI in marginalized regions and apply them for rural communities.
A Comparison of Proton Stopping Power Measured with Proton CT and x-ray CT in Fresh Post-Mortem Porcine Structures
Creators: name: DeJongh, Don F.
name: DeJongh, Ethan A.
name: Rykalin, Victor
name: DeFillippo, Greg
name: Pankuch, Mark
name: Best, Andrew W.
name: Coutrakon, George
name: Duffin, Kirk L.
name: Karonis, Nicholas T.
name: Ordoñez, Caesar E.
name: Sarosiek, Christina
name: Schulte, Reinhard W.
name: Winans, John R.
name: Block, Alec M.
name: Hentz, Courtney L.
name: Welsh, James S.
Publisher: name: arXiv
Year: 2020
Subjects: subject: Medical Physics (physics.med-ph)
subject: FOS: Physical sciences

description: Purpose: Currently, calculations of proton range in proton therapy patients are based on a conversion of CT Hounsfield Units of patient tissues into proton relative stopping power. Uncertainties in this conversion necessitate larger proximal and distal planned target volume margins. Proton CT can potentially reduce these uncertainties by directly measuring proton stopping power. We aim to demonstrate proton CT imaging with complex porcine samples, to analyze in detail three-dimensional regions of interest, and to compare proton stopping powers directly measured by proton CT to those determined from x-ray CT scans. Methods: We have used a prototype proton imaging system with single proton tracking to acquire proton radiography and proton CT images of a sample of porcine pectoral girdle and ribs, and a pig's head. We also acquired close in time x-ray CT scans of the same samples, and compared proton stopping power measurements from the two modalities. In the case of the pig's head, we obtained x-ray CT scans from two different scanners, and compared results from high-dose and low-dose settings. Results: Comparing our reconstructed proton CT images with images derived from x-ray CT scans, we find agreement within 1% to 2% for soft tissues, and discrepancies of up to 6% for compact bone. We also observed large discrepancies, up to 40%, for cavitated regions with mixed content of air, soft tissue, and bone, such as sinus cavities or tympanic bullae. Conclusions: Our images and findings from a clinically realistic proton CT scanner demonstrate the potential for proton CT to be used for low-dose treatment planning with reduced margins.
description: Accepted for publication in Medical Physics
High resolution spectroscopy of bright subdwarf B stars - I. Radial velocity variables
Creators: name: Edelmann, H.
name: Heber, U.
name: Altmann, M.
name: Karl, C.
name: Lisker, T.
Publisher: name: arXiv
Year: 2005
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: Radial velocity curves for 15 bright subdwarf B binary systems have been measured using high precision radial velocity measurements from high S/N optical high-resolution spectra. In addition, two bright sdB stars are discovered to be radial velocity variable but the period could not yet be determined. The companions for all systems are unseen. The periods range from about 0.18 days up to more than ten days. The radial velocity semi amplitudes are found to lie between 15 and 130 km/s. Using the mass functions, the masses of the unseen companions have been constrained to lower limits of 0.03 up to 0.55 M_sun, and most probable values of 0.03 up to 0.81 M_sun. The invisible companions for three of our program stars are undoubtedly white dwarfs. In the other cases they could be either white dwarfs or main sequence stars. For two stars the secondaries could possibly be brown dwarfs. As expected, the orbits are circular for most of the systems. However, for one third of the program stars we find slightly eccentric orbits with small eccentricities of e~0.02-0.06. This is the first time that non-circular orbits have been found in sdB binaries. No correlation with the orbital period can be found.
description: Accepted for publication in A&A, 10 pages, 5 figures, quality of Fig.2 is downgraded to fit in the astroph requirements
Role of solvent for globular proteins in solution
Creators: name: Shiryayev, A.
name: Pagan, D. L.
name: Gunton, J. D.
name: Rhen, D. S.
name: Saxena, A.
name: Lookman, T.
Publisher: name: arXiv
Year: 2005
Subjects: subject: Soft Condensed Matter (cond-mat.soft)
subject: FOS: Physical sciences

description: The properties of the solvent affect the behavior of the solution. We propose a model that accounts for the contribution of the solvent free energy to the free energy of globular proteins in solution. For the case of an attractive square well potential, we obtain an exact mapping of the phase diagram of this model without solvent to the model that includes the solute-solvent contribution. In particular we find for appropriate choices of parameters upper critical points, lower critical points and even closed loops with both upper and lower critical points, similar to one found before [Macromolecules, 36, 5845 (2003)]. In the general case of systems whose interactions are not attractive square wells, this mapping procedure can be a first approximation to understand the phase diagram in the presence of solvent. We also present simulation results for both the square well model and a modified Lennard-Jones model.
description: 18 pages, 9 figures
Anisotropically Inflating Universes
Creators: name: Barrow, John D.
name: Hervik, Sigbjorn
Publisher: name: arXiv
Year: 2005
Subjects: subject: General Relativity and Quantum Cosmology (gr-qc)
subject: Astrophysics (astro-ph)
subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: We show that in theories of gravity that add quadratic curvature invariants to the Einstein-Hilbert action there exist expanding vacuum cosmologies with positive cosmological constant which do not approach the de Sitter universe. Exact solutions are found which inflate anisotropically. This behaviour is driven by the Ricci curvature invariant and has no counterpart in the general relativistic limit. These examples show that the cosmic no-hair theorem does not hold in these higher-order extensions of general relativity and raises new questions about the ubiquity of inflation in the very early universe and the thermodynamics of gravitational fields.
description: 5 pages, further discussion and references added
Nanoscale atomic waveguides with suspended carbon nanotubes
Creators: name: Peano, V.
name: Thorwart, M.
name: Kasper, A.
name: Egger, R.
Publisher: name: arXiv
Year: 2005
Subjects: subject: Quantum Physics (quant-ph)
subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: FOS: Physical sciences

description: We propose an experimentally viable setup for the realization of one-dimensional ultracold atom gases in a nanoscale magnetic waveguide formed by single doubly-clamped suspended carbon nanotubes. We show that all common decoherence and atom loss mechanisms are small guaranteeing a stable operation of the trap. Since the extremely large current densities in carbon nanotubes are spatially homogeneous, our proposed architecture allows to overcome the problem of fragmentation of the atom cloud. Adding a second nanowire allows to create a double-well potential with a moderate tunneling barrier which is desired for tunneling and interference experiments with the advantage of tunneling distances being in the nanometer regime.
description: Replaced with the published version, 7 pages, 3 figures
2D stationary resistive MHD flows: borderline to magnetic reconnection solutions
Creators: name: Nickeler, Dieter H.
name: Fahr, Hans-Joerg
Publisher: name: arXiv
Year: 2005
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: We present the basic equations for stationary, incompressible resistive MHD flows in two dimensions. This leads to a system of differential equations for two flux functions, one elliptic partial differential equation (Grad-Shafranov-like) for the magnetic flux function and one for the stream function of the flow. In these equations two potentials appear: one potential is a generalized pressure. The second potential couples the magnetic and the flow shear components of the system. With the restriction to flux or at least line conserving flows one has to solve a modified Ohm's law. For the two dimensional case these are two coupled differential equations, which represent the borderline between the resistive but flux conserving (or line conserving) case, and that of reconnective solutions. We discuss some simplified solutions of these equations.
description: 5 pages, 2 figures, Advances in Space Research (in press)
Furoquinolines of the Rutaceae and their role in plant-lepidopteran interactions
Creators: name: Sackett, Tara Elizabeth
Publisher: name: University of British Columbia
Year: 2009

description: Two furoquinoline alkaloids, skimmianine and dictamnine, were purified from the dried leaves of Skimmia japonica (Rutaceae) and dried root of Dictamnus albus (Rutaceae), respectively. The furoquinolines were isolated through acid fractionation and silica gel column chromatography, and their identity was confirmed through HPLC and mass spectroscopic analysis. Skimmianine and dictamnine, as well as the furanocoumarins 8-methoxypsoralen (8-MOP) and 5-methoxypsoralen (5-MOP) were quantified in leaf tissue of S. japonica and Ruta graveolens (Rutaceae). Of these compounds, S. japonica contained skimmianine and 5-MOP, and quantities differed depending on the sex of the plant from which the leaves were taken. The compounds were not present on the surface of the leaves. R. graveolens was found to contain skimmianine, 5-MOP and 8-MOP, both on the surface and interior of the leaves. Neither plant contained detectable levels of dictamnine. Growth assays using Spodoptera litura (Lepidoptera: Noctuidae) and Trichoplusia ni (Lepidoptera: Noctuidae) demonstrated that both furoquinolines are potent antifeedants at concentrations below those found naturally. Skimmianine is twice as deterrent to S. litura as dictamnine on a weight to weight basis. 8-MOP was also deterrent to S. litura, but not as potent as either furoquinoline. Skimmianine was deterrent to T. ni, but 8-MOP had no effect on its growth. Simulated daylight conditions, with appropriate UV wavelengths, were found to have no effect on the antifeedant properties of either furoquinoline or 8-MOP in the S. litura trials. In addition, none of the compounds were physiologically toxic to larvae. It was found that a non-ratio-based method was more accurate than a ratiobased method for the analysis and interpretation of experimental data. In conclusion, the furoquinolines skimmianine and dictamnine, and the furanocoumarin 8-MOP, are deterrent to S. litura larvae. Skimmianine is deterrent to T. ni. The intensity of experimental light conditions may be essential for inducing toxicity in potentially phototoxic compounds.
WANDs of the Black Ring
Creators: name: Pravda, V.
name: Pravdova, A.
Publisher: name: arXiv
Year: 2005
Subjects: subject: General Relativity and Quantum Cosmology (gr-qc)
subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: Necessary conditions for various algebraic types of the Weyl tensor are determined. These conditions are then used to find Weyl aligned null directions for the black ring solution. It is shown that the black ring solution is algebraically special, of type I_i, while locally on the horizon the type is II. One exceptional subclass - the Myers-Perry solution - is of type D.
description: 9 pages, 3 figures
Teaching Architectural Technology with Technology (TEATWIT)
Creators: name: Sanya, Tom
Publisher: name: figshare
Year: 2024
Subjects: classificationCode: 330101
subject: Architectural computing and visualisation methods
classificationCode: 330105
subject: Architectural science and technology
classificationCode: 330102
subject: Architectural design

description: This paper is a reflection on a project that used Computer Aided Design (CAD) modellingto enhance the learning of architectural technology for 2ndyear undergraduate students at the University of Cape Town in the 2010 academic year. A valuable grasp of architectural technology requires understanding of the subject as a construction system with technical limitations that offer creative freedom –a delicate balancing act between convention and innovation.Two buildings of technical and spatial-aesthetic repute were chosen for three dimensional CAD modelling: Fallingwater House(located in USA and designed by Frank Lloyd in 1936) and Die Es(located in South Africa and designed by Gabriel Fagan in 1965). The CAD models, taken from foundation to final roof finish, were elemental and sequentially incremental thus capable of illustrating, at varying scales, individual building components and how they relate to each other as well as to the whole building. The models were madeinto didactic resources comprised of (powerpoint-compatible) images and short movie clips. The representation precision, scale-shift and viewpoint-change possibilities of the dynamic 3D CAD models enhance understanding of building technology per se as well as comprehension of the reciprocal linkage of technical detailing to architectural spatial-aesthetics.A significant number of students who engaged in the learning activities based on the created didactic materials displayed a holistic understanding of architectural technology that superseded a reductivist view of the subject.
Daejeon16 interaction with contact-term corrections for heavy nuclear systems
Creators: name: Papakonstantinou, Panagiota
name: Vary, James P.
name: Kim, Youngman
Publisher: name: arXiv
Year: 2020
Subjects: subject: Nuclear Theory (nucl-th)
subject: FOS: Physical sciences

description: The Daejeon16 two-nucleon interaction is employed in many-body approaches based on the mean-field approximation. The perturbative character of Daejeon16 is verified by comparing results for 16O from the Hartree-Fock (HF) approximation and from the no-core shell model and by examining the magnitude of perturbative corrections to the HF energy in light and heavy nuclei. In order to approximately describe energies and radii across the nuclear chart, a phenomenological correction in the form of a two-plus-three-nucleon contact interaction is introduced. With fitted parameters we achieve a very good description of medium-mass nuclei in terms of energy and size and also in terms of the centroid energy of the giant monopole resonance and the dipole polarizability calculated within the random-phase approximation (RPA). Our results provide further justification for the use of Daejeon16 augmented with phenomenological corrections as an effective interaction of perturbative character in a variety of applications.
description: v3: 29 pages incl. 5 figures, 4 tables; corresponds to published version
TEACHING ARCHITECTURAL TECHNOLOGY WITH TECHNOLOGY (TEATWIT)
Creators: name: Sanya, Tom
Publisher: name: figshare
Year: 2024
Subjects: classificationCode: 330101
subject: Architectural computing and visualisation methods
classificationCode: 330105
subject: Architectural science and technology
classificationCode: 330102
subject: Architectural design

description: This paper is a reflection on a project that used Computer Aided Design (CAD) modellingto enhance the learning of architectural technology for 2ndyear undergraduate students at the University of Cape Town in the 2010 academic year. A valuable grasp of architectural technology requires understanding of the subject as a construction system with technical limitations that offer creative freedom –a delicate balancing act between convention and innovation.Two buildings of technical and spatial-aesthetic repute were chosen for three dimensional CAD modelling: Fallingwater House(located in USA and designed by Frank Lloyd in 1936) and Die Es(located in South Africa and designed by Gabriel Fagan in 1965). The CAD models, taken from foundation to final roof finish, were elemental and sequentially incremental thus capable of illustrating, at varying scales, individual building components and how they relate to each other as well as to the whole building. The models were madeinto didactic resources comprised of (powerpoint-compatible) images and short movie clips. The representation precision, scale-shift and viewpoint-change possibilities of the dynamic 3D CAD models enhance understanding of building technology per se as well as comprehension of the reciprocal linkage of technical detailing to architectural spatial-aesthetics.A significant number of students who engaged in the learning activities based on the created didactic materials displayed a holistic understanding of architectural technology that superseded a reductivist view of the subject.
Inherent nonlinearity of fluid motion and acoustic gravitational wave memory
Creators: name: Datta, Satadal
name: Fischer, Uwe R.
Publisher: name: arXiv
Year: 2020
Subjects: subject: General Relativity and Quantum Cosmology (gr-qc)
subject: Quantum Gases (cond-mat.quant-gas)
subject: FOS: Physical sciences

description: We consider the propagation of nonlinear sound waves in a perfect fluid at rest. By employing the Riemann wave equation of nonlinear acoustics in one spatial dimension, it is shown that waves carrying a constant density perturbation at their tails produce an acoustic analogue of gravitational wave memory. For the acoustic memory, which is in general $nonlinear$, the nonlinearity of the effective spacetime dynamics is not due to the Einstein equations, but due to the nonlinearity of the perfect fluid equations. For concreteness, we employ a box-trapped Bose-Einstein condensate, and suggest an experimental protocol to observe acoustic gravitational wave memory.
description: 10 pages, 3 figures; as published in Physical Review D
PrkA controls peptidoglycan biosynthesisthrough the essential phosphorylation ofReoM
Creators: name: Wamp, Sabrina
name: Rutter, Zoe J
name: Rismondo, Jeanine
name: Jennings, Claire E
name: Möller, Lars
name: Lewis, Richard J
name: Halbedel, Sven
Publisher: name: Robert Koch-Institut
Year: 2020
Subjects: subject: Research Article
subject: Microbiology and Infectious Disease
subject: Pasta-Domain
subject: serine/threonine protein kinase
subject: peptidoglycan
subject: protein degradation
subject: ClpCP protease
subject: 610 Medizin und Gesundheit

description: Peptidoglycan (PG) is the main component of bacterial cell walls and the target formany antibiotics. PG biosynthesis is tightly coordinated with cell wall growth and turnover, andmany of these control activities depend upon PASTA-domain containing eukaryotic-like serine/threonine protein kinases (PASTA-eSTK) that sense PG fragments. However, only a few PGbiosynthetic enzymes are direct kinase substrates. Here, we identify the conserved ReoM proteinas a novel PASTA-eSTK substrate in the Gram-positive pathogenListeria monocytogenes. Our datashow that the phosphorylation of ReoM is essential as it controls ClpCP-dependent proteolyticdegradation of the essential enzyme MurA, which catalyses the first committed step in PGbiosynthesis. We also identify ReoY as a second novel factor required for degradation of ClpCPsubstrates. Collectively, our data imply that the first committed step of PG biosynthesis is activatedthrough control of ClpCP protease activity in response to signals of PG homeostasis imbalance.