Probabilistic Risk Analysis and Margin Process for a Flexible Thermal Protection System

Atmospheric entry vehicle thermal protection systems are margined due to the uncertainties that exist in entry aeroheating environments and the thermal response of the materials and structures. Entry vehicle thermal protections systems are traditionally over-margined for the heat loads that are experienced along the entry trajectory by designing to survive stacked worst-case scenarios. Additionally, the conventional heat shield design and margin process offers very little insight into the risk of over-temperature during flight and the corresponding reliability of the heat shield performance. A probabilistic margin process can be used to appropriately margin the thermal protection system based on rigorously calculated risk of failure. This probabilistic margin process allows engineers to make informed aeroshell design, entry-trajectory design, and risk trades while preventing excessive margin from being applied. This study presents the methods of the probabilistic margin process and how the uncertainty analysis is used to determine the reliability of the entry vehicle thermal protection system and associated risks of failure

The Envelope Kinematics and a Possible Disk Around the Class 0 Protostar within BHR7

We present a characterization of the protostar embedded within the BHR7 dark cloud, based on both photometric measurements from the near-infrared to millimeter and interferometric continuum and molecular line observations at millimeter wavelengths. We find that this protostar is a Class 0 system, the youngest class of protostars, measuring its bolometric temperature to be 50.5~K, with a bolometric luminosity of 9.3~L$_{\odot}$. The near-infrared and \textit{Spitzer} imaging show a prominent dark lane from dust extinction separating clear bipolar outflow cavities. Observations of $^{13}$CO ($J=2\rightarrow1$), C$^{18}$O ($J=2\rightarrow1$), and other molecular lines with the Submillimeter Array (SMA) exhibit a clear rotation signature on scales $<$1300~AU. The rotation can be traced to an inner radius of $\sim$170~AU and the rotation curve is consistent with an R$^{-1}$ profile, implying that angular momentum is being conserved. Observations of the 1.3~mm dust continuum with the SMA reveal a resolved continuum source, extended in the direction of the dark lane, orthogonal to the outflow. The deconvolved size of the continuum indicates a radius of $\sim$100~AU for the continuum source at the assumed distance of 400~pc. The visibility amplitude profile of the continuum emission cannot be reproduced by an envelope alone and needs a compact component. Thus, we posit that the resolved continuum source could be tracing a Keplerian disk in this very young system. If we assume that the continuum radius traces a Keplerian disk (R$\sim$120~AU) the observed rotation profile is consistent with a protostar mass of 1.0~$M_{\odot}$.Comment: 36 pages; 11 Figures, 2 Tables; Accepted to Ap

Aerothermal Ground Testing of Flexible Thermal Protection Systems for Hypersonic Inflatable Aerodynamic Decelerators

Flexible TPS development involves ground testing and analysis necessary to characterize performance of the FTPS candidates prior to flight testing. This paper provides an overview of the analysis and ground testing efforts performed over the last year at the NASA Langley Research Center and in the Boeing Large-Core Arc Tunnel (LCAT). In the LCAT test series, material layups were subjected to aerothermal loads commensurate with peak re-entry conditions enveloping a range of HIAD mission trajectories. The FTPS layups were tested over a heat flux range from 20 to 50 W/cm with associated surface pressures of 3 to 8 kPa. To support the testing effort a significant redesign of the existing shear (wedge) model holder from previous testing efforts was undertaken to develop a new test technique for supporting and evaluating the FTPS in the high-temperature, arc jet flow. Since the FTPS test samples typically experience a geometry change during testing, computational fluid dynamic (CFD) models of the arc jet flow field and test model were developed to support the testing effort. The CFD results were used to help determine the test conditions experienced by the test samples as the surface geometry changes. This paper includes an overview of the Boeing LCAT facility, the general approach for testing FTPS, CFD analysis methodology and results, model holder design and test methodology, and selected thermal results of several FTPS layups

The Chemodynamics of the Stellar Populations in M31 from APOGEE Integrated Light Spectroscopy

We present analysis of nearly 1,000 near-infrared, integrated light spectra from APOGEE in the inner $\sim$7 kpc of M31. We utilize full spectrum fitting with A-LIST simple stellar population spectral templates that represent a population of stars with the same age, [M/H], and [$\alpha$/M]. With this, we determine the mean kinematics, metallicities, $\alpha$ abundances, and ages of the stellar populations of M31's bar, bulge, and inner disk ($\sim$4-7 kpc). We find a non-axisymmetric velocity field in M31 resulting from the presence of a bar. The bulge of M31 is metal-poor relative to the disk ([M/H] = $-0.149^{+0.067}_{-0.081}$ dex), features minima in metallicity on either side of the bar ([M/H] $\sim$ -0.2), and is enhanced in $\alpha$ abundance ([$\alpha$/M] = $0.281^{+0.035}_{-0.038}$). The disk of M31 within $\sim$7 kpc is enhanced in both metallicity ([M/H] = $-0.023^{+0.050}_{-0.052}$) and $\alpha$ abundance ([$\alpha$/M] = $0.274^{+0.020}_{-0.025}$). Both of these structural components are uniformly old at $\simeq$ 12 Gyr. We find the metallicity increases with distance from the center of M31, with the steepest gradient along the disk major axis ($0.043\pm0.021$ dex/kpc). This gradient is the result of changing light contributions from the metal-poor bulge and metal-rich disk. The chemodynamics of stellar populations encodes information about a galaxy's chemical enrichment, star formation history, and merger history, allowing us to discuss new constraints on M31's formation. Our results provide a stepping stone between our understanding of the Milky Way and other external galaxies

WARNING: Physics Envy May Be Hazardous To Your Wealth!

The quantitative aspirations of economists and financial analysts have for many years been based on the belief that it should be possible to build models of economic systems - and financial markets in particular - that are as predictive as those in physics. While this perspective has led to a number of important breakthroughs in economics, "physics envy" has also created a false sense of mathematical precision in some cases. We speculate on the origins of physics envy, and then describe an alternate perspective of economic behavior based on a new taxonomy of uncertainty. We illustrate the relevance of this taxonomy with two concrete examples: the classical harmonic oscillator with some new twists that make physics look more like economics, and a quantitative equity market-neutral strategy. We conclude by offering a new interpretation of tail events, proposing an "uncertainty checklist" with which our taxonomy can be implemented, and considering the role that quants played in the current financial crisis.Comment: v3 adds 2 reference

Controls on the diurnal streamflow cycles in two subbasins of an alpine headwater catchment

In high-altitude alpine catchments, diurnal streamflow cycles are typically dominated by snowmelt or ice melt. Evapotranspiration-induced diurnal streamflow cycles are less observed in these catchments but might happen simultaneously. During a field campaign in the summer 2012 in an alpine catchment in the Swiss Alps (Val Ferret catchment, 20.4 km2, glaciarized area: 2%), we observed a transition in the early season from a snowmelt to an evapotranspiration-induced diurnal streamflow cycle in one of two monitored subbasins. The two different cycles were of comparable amplitudes and the transition happened within a time span of several days. In the second monitored subbasin, we observed an ice melt-dominated diurnal cycle during the entire season due to the presence of a small glacier. Comparisons between ice melt and evapotranspiration cycles showed that the two processes were happening at the same times of day but with a different sign and a different shape. The amplitude of the ice melt cycle decreased exponentially during the season and was larger than the amplitude of the evapotranspiration cycle which was relatively constant during the season. Our study suggests that an evapotranspiration-dominated diurnal streamflow cycle could damp the ice melt-dominated diurnal streamflow cycle. The two types of diurnal streamflow cycles were separated using a method based on the identification of the active riparian area and measurement of evapotranspiration

Using quantitative single molecule localization microscopy to optimize multivalent HER2-targeting ligands

IntroductionThe progression-free survival of patients with HER2-positive metastatic breast cancer is significantly extended by a combination of two monoclonal antibodies, trastuzumab and pertuzumab, which target independent epitopes of the extracellular domain of HER2. The improved efficacy of the combination over individual antibody therapies targeting HER2 is still being investigated, and several molecular mechanisms may be in play: the combination downregulates HER2, improves antibody-dependent cell mediated cytotoxicity, and/or affects the organization of surface-expressed antigens, which may attenuate downstream signaling.MethodsBy combining protein engineering and quantitative single molecule localization microscopy (qSMLM), here we both assessed and optimized clustering of HER2 in cultured breast cancer cells.ResultsWe detected marked changes to the cellular membrane organization of HER2 when cells were treated with therapeutic antibodies. When we compared untreated samples to four treatment scenarios, we observed the following HER2 membrane features: (1) the monovalent Fab domain of trastuzumab did not significantly affect HER2 clustering; (2) individual therapy with either trastuzumab or (3) pertuzumab produced significantly higher levels of HER2 clustering; (4) a combination of trastuzumab plus pertuzumab produced the highest level of HER2 clustering. To further enhance this last effect, we created multivalent ligands using meditope technology. Treatment with a tetravalent meditope ligand combined with meditope-enabled trastuzumab resulted in pronounced HER2 clustering. Moreover, compared to pertuzumab plus trastuzumab, at early time points this meditope-based combination was more effective at inhibiting epidermal growth factor (EGF) dependent activation of several downstream protein kinases.DiscussionCollectively, mAbs and multivalent ligands can efficiently alter the organization and activation of the HER2 receptors. We expect this approach could be used in the future to develop new therapeutics

The Simultaneous Formation of Massive Stars and Stellar Clusters

We show that massive stars and stellar clusters are formed simultaneously, the global evolution of the forming cluster is what allows the central stars to become massive. We predict that massive star forming clumps, such as those observed in Motte et al. 2007, contract and grow in mass leading to the formation of massive stars. This occurs as mass is continually channeled from large radii onto the central proto-stars, which can become massive through accretion. Using SPH simulations of massive star forming clumps in a Giant Molecular Cloud, we show that clumps are initially diffuse and filamentary, and become more concentrated as they collapse. Simulated interferometry observations of our data provide an explanation as to why young massive star forming regions show more substructure than older ones. The most massive stars in our model are found within the most bound cluster. Most of the mass accreted by the massive stars was originally distributed throughout the clump at low densities, and was later funneled to the star due to global in-fall. Even with radiative feedback no massive pre-stellar cores are formed. The original cores are of intermediate mass and gain their additional mass in the proto-stellar stage. We also find that cores which form low mass stars exist within the volume from which the high mass stars accrete, but are largely unaffected by this process.Comment: Accepted for publication in MNRAS. 11 pages, 9 figures and 3 table

Síntese e avaliação catalítica de catalisadores microporoso, mesoporosos e micro-mesoporosos

As propriedades e potencialidades dos materiais porosos estão em constantes estudos e usos nas mais variadas áreas da ciência. Esses materiais são atribuídos em classes de acordo com o ordenamento dos seus blocos estruturantes. Suas propriedades estão intrinsecamente relacionadas pela sua capacidade de catalisar as reações químicas. Neste trabalho, catalisadores do tipo HAlZSM-12, HAlMCM-41, HAlMCM-48, AlSBA-15 (Si/Al= 25, 50, 75) e HAlZSM-12/HAlMCM-41, HAlZSM-12/HAlMCM-48, HAlZSM-12/AlSBA-15 foram sintetizados pelo método hidrotérmico, submetidas a processos de calcinação e troca iônica e caracterizados por difratometria de raios-X. No presente trabalho também avaliou-se o potencial catalítico dos catalisadores na pirólise catalítica do ácido oléico em escala de bancada usando a termogravimetria. _________________________________________________________________________________________ ABSTRACT: The properties and potential of porous materials are in constant studies and uses in various areas of science. These materials are attributed to classes according to their structural ordering of blocks. Their properties are intrinsically related by their ability to catalyze chemical reactions. In this study, catalysts of type HAlZSM-12, HAlMCM-41, HAlMCM-48, AlSBA-15 (Si/Al 25, 50, 75) and composites HAlZSM-12/HAlMCM-41, HAlZSM-12/HAlMCM-48, HAlZSM-12/AlSBA-15 were synthesized by hydrothermal method, subjected to calcination and ion exchange processes and characterized by X-ray diffraction. In this study also were evaluated the catalytic potential of catalysts in the catalytic pyrolysis of oleic acid in micro-scale tests using thermogravimetric (TG)

The state of the Martian climate

60°N was +2.0°C, relative to the 1981–2010 average value (Fig. 5.1). This marks a new high for the record. The average annual surface air temperature (SAT) anomaly for 2016 for land stations north of starting in 1900, and is a significant increase over the previous highest value of +1.2°C, which was observed in 2007, 2011, and 2015. Average global annual temperatures also showed record values in 2015 and 2016. Currently, the Arctic is warming at more than twice the rate of lower latitudes