On Local Dilatation Invariance

The relationship between local Weyl scaling invariant models and local dilatation invariant actions is critically scrutinized. While actions invariant under local Weyl scalings can be constructed in a straightforward manner, actions invariant under local dilatation transformations can only be achieved in a very restrictive case. The invariant couplings of matter fields to an Abelian vector field carrying a non-trivial scaling weight can be easily built, but an invariant Abelian vector kinetic term can only be realized when the local scale symmetry is spontaneously broken.Comment: 3 page

Why P/OF should look for evidences of over-dense structures in solar flare hard X-ray sources

White-light and hard X-ray (HXR) observations of two white-light flares (WLFs) show that if the radiative losses in the optical continuum are powered by fast electrons directly heating the WLF source, then the column density constraints imposed by the finite range of the electrons requires that the WLF consist of an over-dense region in the chromosphere, with density exceeding 10 to the 14th power/cu cm. Thus, we recommend that P/OF search for evidences of over-dense structures in HXR images obtained simultaneously with optical observations of flares

Multistability of free spontaneously-curved anisotropic strips

Multistable structures are objects with more than one stable conformation, exemplified by the simple switch. Continuum versions are often elastic composite plates or shells, such as the common measuring tape or the slap bracelet, both of which exhibit two stable configurations: rolled and unrolled. Here we consider the energy landscape of a general class of multistable anisotropic strips with spontaneous Gaussian curvature. We show that while strips with non-zero Gaussian curvature can be bistable, strips with positive spontaneous curvature are always bistable, independent of the elastic moduli, strips of spontaneous negative curvature are bistable only in the presence of spontaneous twist and when certain conditions on the relative stiffness of the strip in tension and shear are satisfied. Furthermore, anisotropic strips can become tristable when their bending rigidity is small. Our study complements and extends the theory of multistability in anisotropic shells and suggests new design criteria for these structures.Comment: 20 pages, 10 figure

Net energy analysis of solar and conventional domestic hot water systems in Melbourne, Australia

It is commonly assumed that solar hot water systems save energy and reduce greenhouse gas emissions. Very rarely has the life-cycle energy requirements of solar hot water systems been analysed, including their embodied energy. The extent to which solar hot water systems save energy compared to conventional systems in Melbourne, Australia, is shown through a comparative net energy analysis. The solar systems provided a net energy saving compared to the conventional systems after 0.5 to 2 years, for electricity and gas systems respectively.<br /

Accelerated process development for integrated end-to-end biologics manufacturing

With the exception of monoclonal antibodies, biologics typically require bespoke manufacturing processes that vary widely in the type of and number of unit operations. This constraint leads to custom facility designs and unique strategies for process development for every new molecule. To enable flexible, multi-product manufacturing facilities and to reduce the speed to clinic for new molecules, streamlined manufacturing processes and associated strategies for process development are needed. We have developed a bench-scale, integrated and automated manufacturing platform capable of rapidly producing a variety of recombinant proteins with phase-appropriate quality for early development1. The system comprises three modules for fermentation via perfusion, straight-through chromatographic purification, and formulation. To facilitate the production of multiple products on the same system, we have also developed a holistic strategy for process design to manufacture new products in as few as twelve weeks after obtaining the product sequence. While upstream process development in our host (Pichia pastoris) has been relatively straightforward, there are not many tools currently available for developing fully integrated straight-through chromatographic processes. Therefore, we developed an in silico tool for the prediction of fully integrated purification processes based on a one-time collection of host-related data combined with conventional high-throughput chromatographic screening data for each new target molecule2. We used this tool to develop fully integrated, end-to-end production processes for three molecules (hGH, IFNα-2b, and G-CSF) with at least 45% fewer steps than traditional processes. While our in silico tool allows for rapid resin selection, it may not predict the optimal process for each individual molecule since it is based on conventional high-throughput screening techniques which seek to optimize each chromatographic step independently rather than optimizing a fully integrated, multi-column process. To address this limitation, we have also developed a DoE-like framework for the optimization of fully integrated purification processes once the resins have been selected. First, a series of range finding experiments are carried out on each individual column, similar to conventional screening but with limited analytics. Next, we carry out fully integrated (multi-column) testing of the proposed operational area with more extensive analytics, including host cell protein, DNA, and yield measurements. We use this methodology to develop optimized processes for the end-to-end production of a variety of single domain antibodies with high yield and purity. Further, we present a method for predicting the optimal operating conditions for a new molecule within the same class based only on its biophysical characteristics, reducing the timeline from sequence to early stage, phase-appropriate product to only six weeks. Using these holistic strategies for process development, we have produced over ten different recombinant proteins on our manufacturing platform including enzymes, cytokines, singe domain antibodies, and vaccine subunits. We believe that such integrated strategies for process design could enable the rapid translation from sequence to early stage clinical development of products for a variety of molecules and potentially allow clinical testing of a greater number of high quality molecules for vaccines and biopharmaceuticals. 1. Crowell, L. E. et al. On-demand manufacturing of clinical-quality biopharmaceuticals. Nat. Biotechnol. (2018). doi:10.1038/nbt.4262 2. Timmick, S. M. et al. An impurity characterization based approach for the rapid development of integrated downstream purification processes. Biotechnol. Bioeng. 1–13 (2018). doi:10.1002/bit.2671

Charged spin 1/2 particle in an arbitrary magnetic field in two spatial dimensions: a supersymmetric quantum mechanical system

It is shown that the 2 X 2 matrix Hamiltonian describing the dynamics of a charged spin 1/2 particle with g-factor 2 moving in an arbitrary, spatially dependent, magnetic field in two spatial dimensions can be written as the anticommuator of a nilpotent operator and its hermitian conjugate. Consequently, the Hamiltonians for the two different spin projections form partners of a supersymmetric quantum mechanical system. The resulting supersymmetry algebra can then be exploited to explicitly construct the exact zero energy ground state wavefunction for the system. Modulo this ground state, the remainder of the eigenstates and eigenvalues of the two partner Hamiltonians form positive energy degenerate pairs. We also construct the spatially asymptotic form of the magnetic field which produces a finite magnetic flux and associated zero energy normalizable ground state wavefunction.Comment: 10 pages, LaTe

Instantons, supersymmetric vacua, and emergent geometries

We study instanton solutions and superpotentials for the large number of vacua of the plane-wave matrix model and a 2+1 dimensional Super Yang-Mills theory on $R\times S^2$ with sixteen supercharges. We get the superpotential in the weak coupling limit from the gauge theory description. We study the gravity description of these instantons. Perturbatively with respect to a background, they are Euclidean branes wrapping cycles in the dual gravity background. Moreover, the superpotential can be given by the energy of the electric charge system characterizing each vacuum. These charges are interpreted as the eigenvalues of matrices from a reduction for the 1/8 BPS sector of the gauge theories. We also discuss qualitatively the emergence of the extra spatial dimensions appeared on the gravity side.Comment: 29 pages, 3 figures, latex. v2: references added, comments added. v3: accepted version in PR

Fluorescence Imaging of Underexpanded Jets and Comparison with CFD

An experimental study of underexpanded and highly underexpanded axisymmetric nitrogen free jets seeded with 0.5% nitric oxide (NO) and issuing from a sonic orifice was conducted at NASA Langley Research Center. Reynolds numbers based on nozzle exit conditions ranged from 770 to 35,700, and nozzle exit-to-ambient jet pressure ratios ranged from 2 to 35. These flows were non-intrusively visualized with a spatial resolution of approximately 0.14 mm x 0.14 mm x 1 mm thick and a temporal resolution of 1 s using planar laser-induced fluorescence (PLIF) of NO, with the laser tuned to the strongly-fluorescing UV absorption bands of the Q1 band head near 226.256 nm. Three laminar cases were selected for comparison with computational fluid dynamics (CFD). The cases were run using GASP (General Aerodynamic Simulation Program) Version 4. Comparisons of the fundamental wavelength of the jet flow showed good agreement between CFD and experiment for all three test cases, while comparisons of Mach disk location and Mach disk diameter showed good agreement at lower jet pressure ratios, with a tendency to slightly underpredict these parameters with increasing jet pressure ratio

Paper Session I-B - Reverse Engineering of Biological Gravity-Sensing Organs: Neurocomputational and Biomedical Implications

As humans began to project themselves into the environment of interplanetary space during the early 1960s, it was clear that the opening of this new frontier would require a comprehensive understanding of the effects of near-weightlessness (microgravity) on biological organisms. After all, life on planet Earth has evolved under the stable and pervasive influence of gravity. In terrestrial ecosystems, a force of one gravitational unit represents a continuous epigenetic agent that affects living systems at levels ranging from the morphogenetic to the behavioral2. However, an unexpected, beneficial outcome of research in gravitational biology and medicine is that it not only improves the conditions and prospects for space travelers, but it also results in enhanced knowledge that could contribute to the solution of physiological and biomedical problems for humans here on Earth3. Several Space Shuttle missions over the past decade have included experiments aimed at improving our understanding of the effect of microgravity on living organisms. For instance, the recent orbiter Columbia mission Neurolab (STS-90), proposed at the beginning of this ÒDecade of the BrainÓ, focused on basic neuroscience questions which will not only expand our understanding of how the nervous system develops and functions in space, but also increase our knowledge about how it develops and functions on Earth, thus contributing to the study and treatment of neurological diseases and disorders

Paper Session III-B - Development of Biomolecular Techniques for the Analysis of Gravity Sensing Mechanisms in Space Flight Specimens: Applications in Biomedicine and Gravitational Biology

On Earth, the origin and evolution of life has been influenced by constant exposure to a gravitational field. An ever-present epigenetic (extrinsic) force of one gravitational unit (1g) affects the morphology, development, physiology, and behavior of living organisms; the extent and diversity of adaptations to this force underscore its importance as an environmental factor1,2. Changes in the gravitational environment often have drastic and pleiotropic consequences, and have been described empirically for numerous organisms ranging from humans and mice to snails and plants, and even bacteria3,4. We must be able to compensate for these changes before we can plan any long-term space flight, including the mission to Mars. However, compensation has as its prerequisite understanding. Elucidation of the cellular, subcellular, and molecular mechanisms responsible for the plethora of descriptive findings of microgravity- or spaceflight- related changes is necessary