Expanding your Horizons: a Program for Engaging Middle School Girls in Science and Mathematics

NASA Astrophysics Data System (ADS)

Jahnke, Tamera S.; Level, Allison V.

Gender equity in science, mathematics, and technology is an issue that has generated the creation of a number of programs. Young women need to be aware that there are a variety of careers in science, mathematics, and technology that they can actively pursue. This article highlights one example of a successful middle school science program in Southwest Missouri. Expanding Your Horizons in Science, Mathematics, and Technology (EYH) integrates keynote speakers, role model mentoring sessions, and small group experiments into a hands-on learning environment. Initial survey results of parents and teachers show support for the conference and indicate that the program helps motivate students to consider careers in science, mathematics, and technology. In addition to the goal of increasing awareness for these young people, there is a need for increased scientific literacy of the general public and an increased application of science to "real world" circumstances. This program addresses these issues.

Expanding Girls' Horizons: Strengthening Persistence in the Early Math and Science Education Pipeline

NASA Astrophysics Data System (ADS)

Virnoche, Mary E.

Little longitudinal or follow-up data is available on the impact of Expanding Your Horizons (EYH) conferences. The purpose of the conferences is to encourage girls to take more math and science in high school by exposing them to hands-on activities and role models in math and science professions. This paper is based on 2005 and 2006 one-to-one and small-group interview data from 22 high school girls who attended an EYH conference during their middle school years. The data suggests that EYH strengthens girls' persistence in math and science pathways. Most girls came to the conferences already interested in math and science and at the urging of parents or teachers. Most felt empowered through the shared experience with hundreds of other girls and women, and relayed detailed and enthusiastic descriptions of hands-on activities. Many of the girls also drew connections between EYH and their course-taking actions and career goals. This paper highlights examples of these experiences and makes recommendations for future math and science early pipeline diversity work.

Identification of black hole horizons using scalar curvature invariants

NASA Astrophysics Data System (ADS)

Coley, Alan; McNutt, David

2018-01-01

We introduce the concept of a geometric horizon, which is a surface distinguished by the vanishing of certain curvature invariants which characterize its special algebraic character. We motivate its use for the detection of the event horizon of a stationary black hole by providing a set of appropriate scalar polynomial curvature invariants that vanish on this surface. We extend this result by proving that a non-expanding horizon, which generalizes a Killing horizon, coincides with the geometric horizon. Finally, we consider the imploding spherically symmetric metrics and show that the geometric horizon identifies a unique quasi-local surface corresponding to the unique spherically symmetric marginally trapped tube, implying that the spherically symmetric dynamical black holes admit a geometric horizon. Based on these results, we propose a suite of conjectures concerning the application of geometric horizons to more general dynamical black hole scenarios.

Black holes in an expanding universe.

PubMed

Gibbons, Gary W; Maeda, Kei-ichi

2010-04-02

An exact solution representing black holes in an expanding universe is found. The black holes are maximally charged and the universe is expanding with arbitrary equation of state (P = w rho with -1 < or = for all w < or = 1). It is an exact solution of the Einstein-scalar-Maxwell system, in which we have two Maxwell-type U(1) fields coupled to the scalar field. The potential of the scalar field is an exponential. We find a regular horizon, which depends on one parameter [the ratio of the energy density of U(1) fields to that of the scalar field]. The horizon is static because of the balance on the horizon between gravitational attractive force and U(1) repulsive force acting on the scalar field. We also calculate the black hole temperature.

Evolving Hořava cosmological horizons

NASA Astrophysics Data System (ADS)

Fathi, Mohsen; Mohseni, Morteza

2016-09-01

Several sets of radially propagating null congruence generators are exploited in order to form 3-dimensional marginally trapped surfaces, referred to as black hole and cosmological apparent horizons in a Hořava universe. Based on this method, we deal with the characteristics of the 2-dimensional space-like spheres of symmetry and the peculiarities of having trapping horizons. Moreover, we apply this method in standard expanding and contracting FLRW cosmological models of a Hořava universe to investigate the conditions under which the extra parameters of the theory may lead to trapped/anti-trapped surfaces both in the future and in the past. We also include the cases of negative time, referred to as the finite past, and discuss the formation of anti-trapped surfaces inside the cosmological apparent horizons.

New Horizons Launch Contingency Effort

NASA Astrophysics Data System (ADS)

Chang, Yale; Lear, Matthew H.; McGrath, Brian E.; Heyler, Gene A.; Takashima, Naruhisa; Owings, W. Donald

2007-01-01

On 19 January 2006 at 2:00 PM EST, the NASA New Horizons spacecraft (SC) was launched from the Cape Canaveral Air Force Station (CCAFS), FL, onboard an Atlas V 551/Centaur/STAR™ 48B launch vehicle (LV) on a mission to explore the Pluto Charon planetary system and possibly other Kuiper Belt Objects. It carried a single Radioisotope Thermoelectric Generator (RTG). As part of the joint NASA/US Department of Energy (DOE) safety effort, contingency plans were prepared to address the unlikely events of launch accidents leading to a near-pad impact, a suborbital reentry, an orbital reentry, or a heliocentric orbit. As the implementing organization. The Johns Hopkins University Applied Physics Laboratory (JHU/APL) had expanded roles in the New Horizons launch contingency effort over those for the Cassini mission and Mars Exploration Rovers missions. The expanded tasks included participation in the Radiological Control Center (RADCC) at the Kennedy Space Center (KSC), preparation of contingency plans, coordination of space tracking assets, improved aerodynamics characterization of the RTG's 18 General Purpose Heat Source (GPHS) modules, and development of spacecraft and RTG reentry breakup analysis tools. Other JHU/APL tasks were prediction of the Earth impact footprints (ElFs) for the GPHS modules released during the atmospheric reentry (for purposes of notification and recovery), prediction of the time of SC reentry from a potential orbital decay, pre-launch dissemination of ballistic coefficients of various possible reentry configurations, and launch support of an Emergency Operations Center (EOC) on the JHU/APL campus. For the New Horizons launch, JHU/APL personnel at the RADCC and at the EOC were ready to implement any real-time launch contingency activities. A successful New Horizons launch and interplanetary injection precluded any further contingency actions. The New Horizons launch contingency was an interagency effort by several organizations. This paper

Gravitational pressure, apparent horizon and thermodynamics of FLRW universe in the teleparallel gravity

NASA Astrophysics Data System (ADS)

da Rocha-Neto, J. F.; Morais, B. R.

2018-04-01

In the context of the teleparallel equivalent of general relativity the concept of gravitational pressure and gravitational energy-momentum arisen in a natural way. In the case of a Friedmann-Lemaitre-Robertson-Walker space FLRW we obtain the total energy contained inside the apparent horizon and the radial pressure over the apparent horizon area. We use these definitions to written a thermodynamics relation TAdSA = dEA+PAdVA at the apparent horizon, where EA is the total energy inside the apparent horizon, VA is the areal volume of the apparent horizon, PA is the radial pressure over the apparent horizon area, SA is the entropy which can be assumed as one quarter of the apparent horizon area only for a non stationary apparent horizon. We identify TA as the temperature at the surface of the apparent horizon. We shown that for all expanding accelerated FLRW model of universe the radial pressure is positive.

Expanding the horizons of disability law in India: a study from a human rights perspective.

PubMed

Chopra, Tushti

2013-01-01

Disabled/"differently abled" persons by virtue of being human have the right to enjoy human rights to life, liberty, equality, security, and dignity. However, due to social indifference, psychological barriers, a limited definition of "disability" entitling protection of law, and a lack of proper data, disabled persons in India remain an invisible category. Although several laws exit to ensure their full and effective participation in society, they remain insufficient as they are primarily based on the government's discretion. At the same time, whenever the judiciary finds an opportunity, it acts as a real protector of disabled persons, but it is not feasible to knock on the door of the judiciary for every request. Interestingly, various civil societies and human rights activists have occasionally asserted the rights of the disabled. However, unless the foundation stones of law are fortified, disabled persons cannot fully realize their rights. It is high time to enact effective laws, with timely implementation, to protect their interests and empower their capabilities that are based on a "rights-based approach" rather than on the charity, medical, or social approaches. Thus, the horizons of law must be expanded to provide a "human friendly environment" for all of the disabled to overcome the barriers that impair their development. © 2013 American Society of Law, Medicine & Ethics, Inc.

Broadening the Horizons: Organizational Communication in the Real World.

ERIC Educational Resources Information Center

Swanson, Georgia

Working in the microcosm of an individual class, organizational communication instructors can broaden the student's horizon by starting with what are local types of diversity and then expanding the classroom understanding to include the larger world where that student is going to live and work. Speech communication teachers/scholars have seen…

Expanding horizons. Integrating environmental health in occupational health nursing.

PubMed

Rogers, B; Cox, A R

1998-01-01

1. Environmental hazards are ubiquitous. Many exist in the workplace or occur as a result of work process exposures. 2. Environmental health is a natural component of the expanding practice of occupational health nursing. 3. AAOHN's vision for occupational and environmental health will continue to set the standard and provide leadership in the specialty.

Supertranslations: redundancies of horizon data and global symmetries at null infinity

NASA Astrophysics Data System (ADS)

Sousa, K.; Miláns del Bosch, G.; Reina, B.

2018-03-01

We characterise the geometrical nature of smooth supertranslations defined on a generic non-expanding horizon (NEH) embedded in vacuum. To this end we consider the constraints imposed by the vacuum Einstein’s equations on the NEH structure, and discuss the transformation properties of their solutions under supertranslations. We present a freely specifiable data set which is both necessary and sufficient to reconstruct the full horizon geometry, and is composed of objects which are invariant under supertranslations. We conclude that smooth supertranslations do not transform the geometry of the NEH and that they should be regarded as pure gauge. Our results apply both to stationary and non-stationary states of a NEH, the latter ones being able to describe radiative processes taking place on the horizon. As a consistency check we repeat the analysis for Bondi–Metzner–Sachs (BMS) supertranslations defined on null infinity, \

Entropy and temperature from black-hole/near-horizon-CFT duality

NASA Astrophysics Data System (ADS)

Rodriguez, Leo; Yildirim, Tuna

2010-08-01

We construct a two-dimensional CFT, in the form of a Liouville theory, in the near-horizon limit of four- and three-dimensional black holes. The near-horizon CFT assumes two-dimensional black hole solutions first introduced by Christensen and Fulling (1977 Phys. Rev. D 15 2088-104) and expanded to a greater class of black holes via Robinson and Wilczek (2005 Phys. Rev. Lett. 95 011303). The two-dimensional black holes admit a Diff(S1) subalgebra, which upon quantization in the horizon limit becomes Virasoro with calculable central charge. This charge and the lowest Virasoro eigen-mode reproduce the correct Bekenstein-Hawking entropy of the four- and three-dimensional black holes via the known Cardy formula (Blöte et al 1986 Phys. Rev. Lett. 56 742; Cardy 1986 Nucl. Phys. B 270 186). Furthermore, the two-dimensional CFT's energy-momentum tensor is anomalous. However, in the horizon limit the energy-momentum tensor becomes holomorphic equaling the Hawking flux of the four- and three-dimensional black holes. This encoding of both entropy and temperature provides a uniformity in the calculation of black hole thermodynamic and statistical quantities for the non-local effective action approach.

Improvement to Airport Throughput Using Intelligent Arrival Scheduling and an Expanded Planning Horizon

NASA Technical Reports Server (NTRS)

Glaab, Patricia C.

2012-01-01

The first phase of this study investigated the amount of time a flight can be delayed or expedited within the Terminal Airspace using only speed changes. The Arrival Capacity Calculator analysis tool was used to predict the time adjustment envelope for standard descent arrivals and then for CDA arrivals. Results ranged from 0.77 to 5.38 minutes. STAR routes were configured for the ACES simulation, and a validation of the ACC results was conducted comparing the maximum predicted time adjustments to those seen in ACES. The final phase investigated full runway-to-runway trajectories using ACES. The radial distance used by the arrival scheduler was incrementally increased from 50 to 150 nautical miles (nmi). The increased Planning Horizon radii allowed the arrival scheduler to arrange, path stretch, and speed-adjust flights to more fully load the arrival stream. The average throughput for the high volume portion of the day increased from 30 aircraft per runway for the 50 nmi radius to 40 aircraft per runway for the 150 nmi radius for a traffic set representative of high volume 2018. The recommended radius for the arrival scheduler s Planning Horizon was found to be 130 nmi, which allowed more than 95% loading of the arrival stream.

Expanding the horizons of microRNA bioinformatics.

PubMed

Huntley, Rachael P; Kramarz, Barbara; Sawford, Tony; Umrao, Zara; Kalea, Anastasia Z; Acquaah, Vanessa; Martin, Maria-Jesus; Mayr, Manuel; Lovering, Ruth C

2018-06-05

MicroRNA regulation of key biological and developmental pathways is a rapidly expanding area of research, accompanied by vast amounts of experimental data. This data, however, is not widely available in bioinformatic resources, making it difficult for researchers to find and analyse microRNA-related experimental data and define further research projects. We are addressing this problem by providing two new bioinformatics datasets that contain experimentally verified functional information for mammalian microRNAs involved in cardiovascular-relevant, and other, processes. To date, our resource provides over 3,900 Gene Ontology annotations associated with almost 500 miRNAs from human, mouse and rat and over 2,200 experimentally validated miRNA:target interactions. We illustrate how this resource can be used to create miRNA-focused interaction networks with a biological context using the known biological role of miRNAs and the mRNAs they regulate, enabling discovery of associations between gene products, biological pathways and, ultimately, diseases. This data will be crucial in advancing the field of microRNA bioinformatics and will establish consistent datasets for reproducible functional analysis of microRNAs across all biological research areas. Published by Cold Spring Harbor Laboratory Press for the RNA Society.

The cosmological model with a wormhole and Hawking temperature near apparent horizon

NASA Astrophysics Data System (ADS)

Kim, Sung-Won

2018-05-01

In this paper, a cosmological model with an isotropic form of the Morris-Thorne type wormhole was derived in a similar way to the McVittie solution to the black hole in the expanding universe. By solving Einstein's field equation with plausible matter distribution, we found the exact solution of the wormhole embedded in Friedmann-Lemaître-Robertson-Walker universe. We also found the apparent cosmological horizons from the redefined metric and analyzed the geometric natures, including causal and dynamic structures. The Hawking temperature for thermal radiation was obtained by the WKB approximation using the Hamilton-Jacobi equation and Hamilton's equation, near the apparent cosmological horizon.

Does horizon entropy satisfy a quantum null energy conjecture?

NASA Astrophysics Data System (ADS)

Fu, Zicao; Marolf, Donald

2016-12-01

A modern version of the idea that the area of event horizons gives 4G times an entropy is the Hubeny-Rangamani causal holographic information (CHI) proposal for holographic field theories. Given a region R of a holographic QFTs, CHI computes A/4G on a certain cut of an event horizon in the gravitational dual. The result is naturally interpreted as a coarse-grained entropy for the QFT. CHI is known to be finitely greater than the fine-grained Hubeny-Rangamani-Takayanagi (HRT) entropy when \\partial R lies on a Killing horizon of the QFT spacetime, and in this context satisfies other non-trivial properties expected of an entropy. Here we present evidence that it also satisfies the quantum null energy condition (QNEC), which bounds the second derivative of the entropy of a quantum field theory on one side of a non-expanding null surface by the flux of stress-energy across the surface. In particular, we show CHI to satisfy the QNEC in 1  +  1 holographic CFTs when evaluated in states dual to conical defects in AdS3. This surprising result further supports the idea that CHI defines a useful notion of coarse-grained holographic entropy, and suggests unprecedented bounds on the rate at which bulk horizon generators emerge from a caustic. To supplement our motivation, we include an appendix deriving a corresponding coarse-grained generalized second law for 1  +  1 holographic CFTs perturbatively coupled to dilaton gravity.

Do event horizons exist?

NASA Astrophysics Data System (ADS)

Baccetti, Valentina; Mann, Robert B.; Terno, Daniel R.

Event horizons are the defining feature of classical black holes. They are the key ingredient of the information loss paradox which, as paradoxes in quantum foundations, is built on a combination of predictions of quantum theory and counterfactual classical features: neither horizon formation nor its crossing by a test body can be detected by a distant observer. Furthermore, horizons are unnecessary for the production of Hawking-like radiation. We demonstrate that when this radiation is taken into account, it can prevent horizon crossing/formation in a large class of models. We conjecture that horizon avoidance is a general feature of collapse. The nonexistence of event horizons dispels the paradox, but opens up important questions about thermodynamic properties of the resulting objects and correlations between different degrees of freedom.

Is Space Really Expanding? A Counterexample

NASA Astrophysics Data System (ADS)

Chodorowski, Michał J.

2007-03-01

In all Friedman models, the cosmological redshift is widely interpreted as a consequence of the general-relativistic phenomenon of expansion of space. Other commonly believed consequences of this phenomenon are superluminal recession velocities of distant galaxies, and the distance to the particle horizon greater than ct (where t is the age of the Universe), in apparent conflict with special relativity. Here, we study a particular Friedman model: empty universe. This model exhibits both cosmological redshift, superluminal velocities and infinite distance to the horizon. However, we show that the cosmological redshift is there simply a relativistic Doppler shift. Moreover, apparently superluminal velocities and ‘acausal’ distance to the horizon are in fact a direct consequence of special-relativistic phenomenon of time dilation, as well as of the adopted definition of distance in cosmology. There is no conflict with special relativity, whatsoever. In particular, inertial recession velocities are subluminal. Since in the real Universe, sufficiently distant galaxies recede with relativistic velocities, these special-relativistic effects must be at least partly responsible for the cosmological redshift and the aforementioned ‘superluminalities’, commonly attributed to the expansion of space. Let us finish with a question resembling a Buddhism-Zen ‘koan’: in an empty universe, what is expanding?

Stabilising the Integrity of Snake Venom mRNA Stored under Tropical Field Conditions Expands Research Horizons

PubMed Central

Logan, Rhiannon A. E.; Leung, Kam-Yin D.; Newberry, Fiona J.; Rowley, Paul D.; Dunbar, John P.; Wagstaff, Simon C.; Casewell, Nicholas R.; Harrison, Robert A.

2016-01-01

Background Snake venoms contain many proteinaceous toxins that can cause severe pathology and mortality in snakebite victims. Interestingly, mRNA encoding such toxins can be recovered directly from venom, although yields are low and quality is unknown. It also remains unclear whether such RNA contains information about toxin isoforms and whether it is representative of mRNA recovered from conventional sources, such as the venom gland. Answering these questions will address the feasibility of using venom-derived RNA for future research relevant to biomedical and antivenom applications. Methodology/Principal Findings Venom was extracted from several species of snake, including both members of the Viperidae and Elapidae, and either lyophilized or immediately added to TRIzol reagent. TRIzol-treated venom was incubated at a range of temperatures (4–37°C) for a range of durations (0–48 hours), followed by subsequent RNA isolation and assessments of RNA quantity and quality. Subsequently, full-length toxin transcripts were targeted for PCR amplification and Sanger sequencing. TRIzol-treated venom yielded total RNA of greater quantity and quality than lyophilized venom, and with quality comparable to venom gland-derived RNA. Full-length sequences from multiple Viperidae and Elapidae toxin families were successfully PCR amplified from TRIzol-treated venom RNA. We demonstrated that venom can be stored in TRIzol for 48 hours at 4–19°C, and 8 hours at 37°C, at minimal cost to RNA quality, and found that venom RNA encoded multiple toxin isoforms that seemed homologous (98–99% identity) to those found in the venom gland. Conclusions/Significance The non-invasive experimental modifications we propose will facilitate the future investigation of venom composition by using venom as an alternative source to venom gland tissue for RNA-based studies, thus obviating the undesirable need to sacrifice snakes for such research purposes. In addition, they expand research horizons

Myostatin: expanding horizons.

PubMed

Sharma, Mridula; McFarlane, Craig; Kambadur, Ravi; Kukreti, Himani; Bonala, Sabeera; Srinivasan, Shruti

2015-08-01

Myostatin is a secreted growth and differentiation factor that belongs to the TGF-β superfamily. Myostatin is predominantly synthesized and expressed in skeletal muscle and thus exerts a huge impact on muscle growth and function. In keeping with its negative role in myogenesis, myostatin expression is tightly regulated at several levels including epigenetic, transcriptional, post-transcriptional, and post-translational. New revelations regarding myostatin regulation also offer mechanisms that could be exploited for developing myostatin antagonists. Increasingly, it is becoming clearer that besides its conventional role in muscle, myostatin plays a critical role in metabolism. Hence, molecular mechanisms by which myostatin regulates several key metabolic processes need to be further explored. © 2015 International Union of Biochemistry and Molecular Biology.

Conformal Killing horizons and their thermodynamics

NASA Astrophysics Data System (ADS)

Nielsen, Alex B.; Shoom, Andrey A.

2018-05-01

Certain dynamical black hole solutions can be mapped to static spacetimes by conformal metric transformations. This mapping provides a physical link between the conformal Killing horizon of the dynamical black hole and the Killing horizon of the static spacetime. Using the Vaidya spacetime as an example, we show how this conformal relation can be used to derive thermodynamic properties of such dynamical black holes. Although these horizons are defined quasi-locally and can be located by local experiments, they are distinct from other popular notions of quasi-local horizons such as apparent horizons. Thus in the dynamical Vaidya spacetime describing constant accretion of null dust, the conformal Killing horizon, which is null by construction, is the natural horizon to describe the black hole.

Asymptotic symmetries on Killing horizons

NASA Astrophysics Data System (ADS)

Koga, Jun-Ichirou

2001-12-01

We investigate asymptotic symmetries regularly defined on spherically symmetric Killing horizons in Einstein theory with or without the cosmological constant. These asymptotic symmetries are described by asymptotic Killing vectors, along which the Lie derivatives of perturbed metrics vanish on a Killing horizon. We derive the general form of the asymptotic Killing vectors and find that the group of asymptotic symmetries consists of rigid O(3) rotations of a horizon two-sphere and supertranslations along the null direction on the horizon, which depend arbitrarily on the null coordinate as well as the angular coordinates. By introducing the notion of asymptotic Killing horizons, we also show that local properties of Killing horizons are preserved not only under diffeomorphisms but also under nontrivial transformations generated by the asymptotic symmetry group. Although the asymptotic symmetry group contains the Diff(S1) subgroup, which results from supertranslations dependent only on the null coordinate, it is shown that the Poisson brackets algebra of the conserved charges conjugate to asymptotic Killing vectors does not acquire nontrivial central charges. Finally, by considering extended symmetries, we discuss the fact that unnatural reduction of the symmetry group is necessary in order to obtain the Virasoro algebra with nontrivial central charges, which is not justified when we respect the spherical symmetry of Killing horizons.

Children's Interstitial and Diffuse Lung Disease. Progress and Future Horizons.

PubMed

Deterding, Robin R

2015-10-01

Children's interstitial and diffuse lung disease (chILD) is a term that encompasses a large and diverse group of rare pediatric diseases and disorders. Significant progress has been made over the last 2 decades in classification, clinical care, research, and organizational structure to enhance the care of children with these high-morbidity and -mortality diseases. New diseases have been defined clinically and genetically, classification systems developed and applied, organizations formed such as the chILD Research Network (chILDRN) and chILD Foundation, and basic and translational science expanded to focus on chILD diseases. Multidisciplinary collaborations and efforts to advance understanding and treatment of chILD have been extended worldwide. The future horizon holds great promise to expand scientific discoveries, collaborate more broadly, and bring new treatment to these children. An overview of key historical past developments, major clinical and research updates, and opportunities for the future in chILD is reviewed in this Perspective.

Black-hole/near-horizon-CFT duality and 4 dimensional classical spacetimes

NASA Astrophysics Data System (ADS)

Rodriguez, Leo L.

2011-09-01

In this thesis we accomplish two goals: We construct a two dimensional conformal field theory (CFT), in the form of a Liouville theory, in the near horizon limit for three and four dimensions black holes. The near horizon CFT assumes the two dimensional black hole solutions that were first introduced by Christensen and Fulling (1977 Phys. Rev. D 15 2088-104) and later expanded to a greater class of black holes via Robinson and Wilczek (2005 Phys. Rev. Lett. 95 011303). The two dimensions black holes admit a Diff( S1) or Witt subalgebra, which upon quantization in the horizon limit becomes Virasoro with calculable central charge. These charges and lowest Virasoro eigen-modes reproduce the correct Bekenstein-Hawking entropy of the four and three dimensions black holes via the Cardy formula (Blote et al 1986 Phys. Rev. Lett. 56 742; Cardy 1986 Nucl. Phys. B 270 186). Furthermore, the two dimensions CFT's energy momentum tensor is anomalous, i.e. its trace is nonzero. However, In the horizon limit the energy momentum tensor becomes holomorphic equaling the Hawking flux of the four and three dimensions black holes. This encoding of both entropy and temperature provides a uniformity in the calculation of black hole thermodynamics and statistical quantities for the non local effective action approach. We also show that the near horizon regime of a Kerr-Newman-AdS (KNAdS) black hole, given by its two dimensional analogue a la Robinson and Wilczek, is asymptotically AdS 2 and dual to a one dimensional quantum conformal field theory (CFT). The s-wave contribution of the resulting CFT's energy-momentum-tensor together with the asymptotic symmetries, generate a centrally extended Virasoro algebra, whose central charge reproduces the Bekenstein-Hawking entropy via Cardy's Formula. Our derived central charge also agrees with the near extremal Kerr/CFT Correspondence in the appropriate limits. We also compute the Hawking temperature of the KNAdS black hole by coupling its

Entropy of black holes with multiple horizons

NASA Astrophysics Data System (ADS)

He, Yun; Ma, Meng-Sen; Zhao, Ren

2018-05-01

We examine the entropy of black holes in de Sitter space and black holes surrounded by quintessence. These black holes have multiple horizons, including at least the black hole event horizon and a horizon outside it (cosmological horizon for de Sitter black holes and "quintessence horizon" for the black holes surrounded by quintessence). Based on the consideration that the two horizons are not independent each other, we conjecture that the total entropy of these black holes should not be simply the sum of entropies of the two horizons, but should have an extra term coming from the correlations between the two horizons. Different from our previous works, in this paper we consider the cosmological constant as the variable and employ an effective method to derive the explicit form of the entropy. We also try to discuss the thermodynamic stabilities of these black holes according to the entropy and the effective temperature.

Expanded solutions of force-free electrodynamics on general Kerr black holes

NASA Astrophysics Data System (ADS)

Li, Huiquan; Wang, Jiancheng

2017-07-01

In this work, expanded solutions of force-free magnetospheres on general Kerr black holes are derived through a radial distance expansion method. From the regular conditions both at the horizon and at spatial infinity, two previously known asymptotical solutions (one of them is actually an exact solution) are identified as the only solutions that satisfy the same conditions at the two boundaries. Taking them as initial conditions at the boundaries, expanded solutions up to the first few orders are derived by solving the stream equation order by order. It is shown that our extension of the exact solution can (partially) cure the problems of the solution: it leads to magnetic domination and a mostly timelike current for restricted parameters.

Generic isolated horizons in loop quantum gravity

NASA Astrophysics Data System (ADS)

Beetle, Christopher; Engle, Jonathan

2010-12-01

Isolated horizons model equilibrium states of classical black holes. A detailed quantization, starting from a classical phase space restricted to spherically symmetric horizons, exists in the literature and has since been extended to axisymmetry. This paper extends the quantum theory to horizons of arbitrary shape. Surprisingly, the Hilbert space obtained by quantizing the full phase space of all generic horizons with a fixed area is identical to that originally found in spherical symmetry. The entropy of a large horizon remains one-quarter its area, with the Barbero-Immirzi parameter retaining its value from symmetric analyses. These results suggest a reinterpretation of the intrinsic quantum geometry of the horizon surface.

Variable horizon in a peridynamic medium

DOE PAGES

Silling, Stewart A.; Littlewood, David J.; Seleson, Pablo

2015-12-10

Here, a notion of material homogeneity is proposed for peridynamic bodies with variable horizon but constant bulk properties. A relation is derived that scales the force state according to the position-dependent horizon while keeping the bulk properties unchanged. Using this scaling relation, if the horizon depends on position, artifacts called ghost forces may arise in a body under a homogeneous deformation. These artifacts depend on the second derivative of the horizon and can be reduced by employing a modified equilibrium equation using a new quantity called the partial stress. Bodies with piecewise constant horizon can be modeled without ghost forcesmore » by using a simpler technique called a splice. As a limiting case of zero horizon, both the partial stress and splice techniques can be used to achieve local-nonlocal coupling. Computational examples, including dynamic fracture in a one-dimensional model with local-nonlocal coupling, illustrate the methods.« less

Dynamical evolution of domain walls in an expanding universe

NASA Technical Reports Server (NTRS)

Press, William H.; Ryden, Barbara S.; Spergel, David N.

1989-01-01

Whenever the potential of a scalar field has two or more separated, degenerate minima, domain walls form as the universe cools. The evolution of the resulting network of domain walls is calculated for the case of two potential minima in two and three dimensions, including wall annihilation, crossing, and reconnection effects. The nature of the evolution is found to be largely independent of the rate at which the universe expands. Wall annihilation and reconnection occur almost as fast as causality allows, so that the horizon volume is 'swept clean' and contains, at any time, only about one, fairly smooth, wall. Quantitative statistics are given. The total area of wall per volume decreases as the first power of time. The relative slowness of the decrease and the smoothness of the wall on the horizon scale make it impossible for walls to both generate large-scale structure and be consistent with quadrupole microwave background anisotropy limits.

New Horizons in Thermodynamics

NASA Astrophysics Data System (ADS)

Hayward, Geoffrey Gordon

1991-02-01

This thesis collects five papers which treat the theory of horizon thermodynamics and its applications to cosmology. In the first paper I consider general, spherically symmetric spacetimes with cosmological and black hole horizons. I find that a state of thermal equilibrium may exist in classical manifolds with two horizons so long as a matter distribution is present. I calculate the Euclidean action for non-classical manifolds with and without boundary and relate it to the grand canonical weighting factor. I find that the mean thermal energy of the cosmological horizon is negative. In the second paper I derive the first law of thermodynamics for bounded, static, spherically symmetric spacetimes which include a matter distribution and either a black hole or cosmological horizon. I calculate heat capacities associated with matter/horizon systems and find that they may be positive or negative depending on the matter configuration. I discuss the case in which the cosmological constant is allowed to vary and conclude that the Hawking/Coleman mechanisms for explaining the low value of the cosmological constant are not well formulated. In the third paper, co-authored by Jorma Louko, we analyze variational principles for non-smooth metrics. These principles give insight to the problem of constructing minisuperspace path integrals in horizon statistical mechanics and quantum cosmology. We demonstrate that smoothness conditions can be derived from the variational principle as equations of motion. We suggest a new prescription for minisuperspace path integrals on the manifold | D times S^2. In the fourth paper, I examine the contribution of the horizon energy density to black hole temperature. I show the existence of positive heat capacity solutions in the small mass regime. In the fifth paper, co-authored by Diego Pavon we investigate the role of primordial black holes in the very early universe under SU(3) times SU(2) times U (1), SU(5), and their supersymmetric

The 2010 Horizon Report

ERIC Educational Resources Information Center

Johnson, L.; Levine, A.; Smith, R.; Stone, S.

2010-01-01

The annual "Horizon Report" describes the continuing work of the New Media Consortium's Horizon Project, a qualitative research project established in 2002 that identifies and describes emerging technologies likely to have a large impact on teaching, learning, or creative inquiry on college and university campuses within the next five years. The…

Two Horizons of Fusion

ERIC Educational Resources Information Center

Lo, Mun Ling; Chik, Pakey Pui Man

2016-01-01

In this paper, we aim to differentiate the internal and external horizons of "fusion." "Fusion" in the internal horizon relates to the structure and meaning of the object of learning as experienced by the learner. It clarifies the interrelationships among an object's critical features and aspects. It also illuminates the…

Fiber-optical analog of the event horizon.

PubMed

Philbin, Thomas G; Kuklewicz, Chris; Robertson, Scott; Hill, Stephen; König, Friedrich; Leonhardt, Ulf

2008-03-07

The physics at the event horizon resembles the behavior of waves in moving media. Horizons are formed where the local speed of the medium exceeds the wave velocity. We used ultrashort pulses in microstructured optical fibers to demonstrate the formation of an artificial event horizon in optics. We observed a classical optical effect: the blue-shifting of light at a white-hole horizon. We also showed by theoretical calculations that such a system is capable of probing the quantum effects of horizons, in particular Hawking radiation.

The Malcolm horizon: History and future

NASA Technical Reports Server (NTRS)

Malcolm, R.

1984-01-01

The development of the Malcolm Horizon, a peripheral vision horizon used in flight simulation, is discussed. A history of the horizon display is presented as well as a brief overview of vision physiology, and the role balance plays is spatial orientation. Avenues of continued research in subconscious cockpit instrumentation are examined.

The 2011 Horizon Report

ERIC Educational Resources Information Center

Johnson, L.; Smith, R.; Willis, H.; Levine, A.; Haywood, K.

2011-01-01

The internationally recognized series of "Horizon Reports" is part of the New Media Consortium's Horizon Project, a comprehensive research venture established in 2002 that identifies and describes emerging technologies likely to have a large impact over the coming five years on a variety of sectors around the globe. This volume, the "2011 Horizon…

A two-mass expanding exact space-time solution

NASA Astrophysics Data System (ADS)

Uzan, Jean-Philippe; Ellis, George F. R.; Larena, Julien

2011-01-01

In order to understand how locally static configurations around gravitationally bound bodies can be embedded in an expanding universe, we investigate the solutions of general relativity describing a space-time whose spatial sections have the topology of a 3-sphere with two identical masses at the poles. We show that Israel junction conditions imply that two spherically symmetric static regions around the masses cannot be glued together. If one is interested in an exterior solution, this prevents the geometry around the masses to be of the Schwarzschild type and leads to the introduction of a cosmological constant. The study of the extension of the Kottler space-time shows that there exists a non-static solution consisting of two static regions surrounding the masses that match a Kantowski-Sachs expanding region on the cosmological horizon. The comparison with a Swiss-Cheese construction is also discussed.

Optimal investment horizons

NASA Astrophysics Data System (ADS)

Simonsen, I.; Jensen, M. H.; Johansen, A.

2002-06-01

In stochastic finance, one traditionally considers the return as a competitive measure of an asset, i.e., the profit generated by that asset after some fixed time span Δt, say one week or one year. This measures how well (or how bad) the asset performs over that given period of time. It has been established that the distribution of returns exhibits ``fat tails'' indicating that large returns occur more frequently than what is expected from standard Gaussian stochastic processes [1-3]. Instead of estimating this ``fat tail'' distribution of returns, we propose here an alternative approach, which is outlined by addressing the following question: What is the smallest time interval needed for an asset to cross a fixed return level of say 10%? For a particular asset, we refer to this time as the investment horizon and the corresponding distribution as the investment horizon distribution. This latter distribution complements that of returns and provides new and possibly crucial information for portfolio design and risk-management, as well as for pricing of more exotic options. By considering historical financial data, exemplified by the Dow Jones Industrial Average, we obtain a novel set of probability distributions for the investment horizons which can be used to estimate the optimal investment horizon for a stock or a future contract.

Cartan invariants and event horizon detection

NASA Astrophysics Data System (ADS)

Brooks, D.; Chavy-Waddy, P. C.; Coley, A. A.; Forget, A.; Gregoris, D.; MacCallum, M. A. H.; McNutt, D. D.

2018-04-01

We show that it is possible to locate the event horizon of a black hole (in arbitrary dimensions) by the zeros of certain Cartan invariants. This approach accounts for the recent results on the detection of stationary horizons using scalar polynomial curvature invariants, and improves upon them since the proposed method is computationally less expensive. As an application, we produce Cartan invariants that locate the event horizons for various exact four-dimensional and five-dimensional stationary, asymptotically flat (or (anti) de Sitter), black hole solutions and compare the Cartan invariants with the corresponding scalar curvature invariants that detect the event horizon.

An in-depth survey of the oil spill literature since 1968: Long term trends and changes since Deepwater Horizon.

PubMed

Murphy, David; Gemmell, Brad; Vaccari, Liana; Li, Cheng; Bacosa, Hernando; Evans, Meredith; Gemmell, Colbi; Harvey, Tracy; Jalali, Maryam; Niepa, Tagbo H R

2016-12-15

In order to characterize the state of oil spill research and describe how the field has changed since its inception in the 1960s and since the Deepwater Horizon spill in 2010, we examined approximately 10% of oil spill literature (1255 of over 11,000 publications) published from 1968 to 2015. We find that, despite its episodic nature, oil spill research is a rapidly expanding field with a growth rate faster than that of science as a whole. There is a massive post-Deepwater Horizon shift of research attention to the Gulf of Mexico, from 2% of studies in 2004-2008 to 61% in 2014-2015, thus ranking Deepwater Horizon as the most studied oil spill. There is, however, a longstanding gap in research in that only 1% of studies deal with the effects of oil spills on human health. These results provide a better understanding of the current trends and gaps within the field. Copyright © 2016 Elsevier Ltd. All rights reserved.

Generalized Robertson-Walker Space-Time Admitting Evolving Null Horizons Related to a Black Hole Event Horizon.

PubMed

Duggal, K L

2016-01-01

A new technique is used to study a family of time-dependent null horizons, called " Evolving Null Horizons " (ENHs), of generalized Robertson-Walker (GRW) space-time [Formula: see text] such that the metric [Formula: see text] satisfies a kinematic condition. This work is different from our early papers on the same issue where we used (1 + n )-splitting space-time but only some special subcases of GRW space-time have this formalism. Also, in contrast to previous work, we have proved that each member of ENHs is totally umbilical in [Formula: see text]. Finally, we show that there exists an ENH which is always a null horizon evolving into a black hole event horizon and suggest some open problems.

Accelerated horizons and Planck-scale kinematics

NASA Astrophysics Data System (ADS)

Arzano, Michele; Laudonio, Matteo

2018-04-01

We extend the concept of accelerated horizons to the framework of deformed relativistic kinematics at the Planck scale. We show that the nontrivial effects due to symmetry deformation manifest in a finite blueshift for field modes as measured by a Rindler observer approaching the horizon. We investigate whether, at a field theoretic level, this effect could manifest in the possibility of a finite horizon contribution to the entropy, a sort of covariant brick wall. In the specific model of symmetry deformation considered, it will turn out that a nondiverging density of modes close to the horizon can be achieved only by introducing a momentum space measure which violates Lorentz invariance.

Horizons versus singularities in spherically symmetric space-times

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bronnikov, K. A.; Elizalde, E.; Odintsov, S. D.

We discuss different kinds of Killing horizons possible in static, spherically symmetric configurations and recently classified as 'usual', 'naked', and 'truly naked' ones depending on the near-horizon behavior of transverse tidal forces acting on an extended body. We obtain the necessary conditions for the metric to be extensible beyond a horizon in terms of an arbitrary radial coordinate and show that all truly naked horizons, as well as many of those previously characterized as naked and even usual ones, do not admit an extension and therefore must be considered as singularities. Some examples are given, showing which kinds of mattermore » are able to create specific space-times with different kinds of horizons, including truly naked ones. Among them are fluids with negative pressure and scalar fields with a particular behavior of the potential. We also discuss horizons and singularities in Kantowski-Sachs spherically symmetric cosmologies and present horizon regularity conditions in terms of an arbitrary time coordinate and proper (synchronous) time. It turns out that horizons of orders 2 and higher occur in infinite proper times in the past or future, but one-way communication with regions beyond such horizons is still possible.« less

78 FR 70976 - Horizons ETFs Management (USA) LLC and Horizons ETF Trust; Notice of Application

Federal Register 2010, 2011, 2012, 2013, 2014

2013-11-27

... SECURITIES AND EXCHANGE COMMISSION [Investment Company Act Release No. 30803; 812-14179] Horizons ETFs Management (USA) LLC and Horizons ETF Trust; Notice of Application November 21, 2013. AGENCY: Securities and Exchange Commission (``Commission''). ACTION: Notice of an application for an order under...

Horizon Entropy from Quantum Gravity Condensates.

PubMed

Oriti, Daniele; Pranzetti, Daniele; Sindoni, Lorenzo

2016-05-27

We construct condensate states encoding the continuum spherically symmetric quantum geometry of a horizon in full quantum gravity, i.e., without any classical symmetry reduction, in the group field theory formalism. Tracing over the bulk degrees of freedom, we show how the resulting reduced density matrix manifestly exhibits a holographic behavior. We derive a complete orthonormal basis of eigenstates for the reduced density matrix of the horizon and use it to compute the horizon entanglement entropy. By imposing consistency with the horizon boundary conditions and semiclassical thermodynamical properties, we recover the Bekenstein-Hawking entropy formula for any value of the Immirzi parameter. Our analysis supports the equivalence between the von Neumann (entanglement) entropy interpretation and the Boltzmann (statistical) one.

Empirical correction for earth sensor horizon radiance variation

NASA Technical Reports Server (NTRS)

Hashmall, Joseph A.; Sedlak, Joseph; Andrews, Daniel; Luquette, Richard

1998-01-01

A major limitation on the use of infrared horizon sensors for attitude determination is the variability of the height of the infrared Earth horizon. This variation includes a climatological component and a stochastic component of approximately equal importance. The climatological component shows regular variation with season and latitude. Models based on historical measurements have been used to compensate for these systematic changes. The stochastic component is analogous to tropospheric weather. It can cause extreme, localized changes that for a period of days, overwhelm the climatological variation. An algorithm has been developed to compensate partially for the climatological variation of horizon height and at least to mitigate the stochastic variation. This method uses attitude and horizon sensor data from spacecraft to update a horizon height history as a function of latitude. For spacecraft that depend on horizon sensors for their attitudes (such as the Total Ozone Mapping Spectrometer-Earth Probe-TOMS-EP) a batch least squares attitude determination system is used. It is assumed that minimizing the average sensor residual throughout a full orbit of data results in attitudes that are nearly independent of local horizon height variations. The method depends on the additional assumption that the mean horizon height over all latitudes is approximately independent of season. Using these assumptions, the method yields the latitude dependent portion of local horizon height variations. This paper describes the algorithm used to generate an empirical horizon height. Ideally, an international horizon height database could be established that would rapidly merge data from various spacecraft to provide timely corrections that could be used by all.

Temporal horizon: modulation by smoking status and gender

PubMed Central

Jones, Bryan A.; Landes, Reid D.; Yi, Richard; Bickel, Warren K.

2009-01-01

Recently, delay discounting has been argued to be conceptually consistent with the notion of temporal horizon (Bickel et al., 2008). Temporal horizon refers to the temporal distance over which behavioral events or objects can influence behavior. Here we examine the results on two putative measures of temporal horizon, future time perspective (FTP) and delay discounting, collected over three separate studies (n = 227), to determine the influence of smoking and gender on temporal horizon. By comparing the results on these temporal horizon measures we address our population of interest: women who smoke. One of the measures of FTP indicates that smoking women have a shorter temporal horizon than their nonsmoking counterparts. Additionally, the story completion measures of FTP are positively correlated with delay discounting. In contrast, results of delay discounting measures showed no difference between smoking women and nonsmoking women, while results of delay discounting measures indicated smoking men have a shorter temporal horizon than non-smoking men. Additionally, the results of the FTP story completion measure indicated that lower third income earners had a shortened temporal horizon compared to upper third income earners. A possible explanation for these results is explored, and the implications of the modulation of temporal horizon by gender and smoking are discussed. PMID:19446407

Firewall or smooth horizon?

NASA Astrophysics Data System (ADS)

Ori, Amos

2016-01-01

Almheiri, Marolf, Polchinski, and Sully pointed out that for a sufficiently old black hole (BH), the set of assumptions known as the complementarity postulates appears to be inconsistent with the assumption of local regularity at the horizon. They concluded that the horizon of an old BH is likely to be the locus of local irregularity, a "firewall". Here I point out that if one adopts a different assumption, namely that semiclassical physics holds throughout its anticipated domain of validity, then the inconsistency is avoided, and the horizon retains its regularity. In this alternative view-point, the vast portion of the original BH information remains trapped inside the BH throughout the semiclassical domain of evaporation, and possibly leaks out later on. This appears to be an inevitable outcome of semiclassical gravity (if assumed to apply throughout its anticipated domain of validity).

The Horizon Report. 2006 Edition

ERIC Educational Resources Information Center

New Media Consortium, 2006

2006-01-01

This third edition of the New Media Consortium's (NMC) annual "Horizon Report" describes the continuing work of the Horizon Project, a research-oriented effort that seeks to identify and describe emerging technologies likely to have a large impact on teaching, learning, or creative expression within higher education. Drawing on ongoing discussions…

The Horizon Report. 2007 Edition

ERIC Educational Resources Information Center

New Media Consortium, 2007

2007-01-01

This fourth edition of the New Media Consortium's (NMC) annual "Horizon Report" describes the continuing work of the Horizon Project, a research-oriented effort that seeks to identify and describe emerging technologies likely to have a large impact on teaching, learning, or creative expression within higher education. Drawing on ongoing…

The need for environmental horizon scanning.

PubMed

Sutherland, William J; Woodroof, Harry J

2009-10-01

Policymakers and practitioners in most fields, including conservation and the environment, often make decisions based on insufficient evidence. One reason for this is that issues appear unexpectedly, when with hindsight, many of them were foreseeable. A solution to the problem of being insufficiently prepared is routine horizon scanning, which we describe as the systematic search for potential threats and opportunities that are currently poorly recognized. Researchers can then decide which issues might be most worthwhile to study. Practitioners can also use horizon scanning to ensure timely policy development and research procurement. Here, we suggest that horizon scanning is an underused tool that should become a standard element of environmental and conservation practice. We make recommendations for its incorporation into research, policy and practice. We argue that, as an ecological and conservation community, we are failing to provide timely advice owing to a weakness in identifying forthcoming issues. We outline possible horizon-scanning methods, and also make recommendations as to how horizon scanning could have a more central role in environmental and conservation practice.

The Horizon Report. 2005 Edition

ERIC Educational Resources Information Center

New Media Consortium, 2005

2005-01-01

This second edition of the New Media Consortium's (NMC) annual "Horizon Report" describes the continuing work of the Horizon Project, a research-oriented effort that seeks to identify and describe emerging technologies likely to have a large impact on teaching, learning, or creative expression within higher education. Drawing on an ongoing series…

The Horizon Report. 2004 Edition

ERIC Educational Resources Information Center

New Media Consortium, 2004

2004-01-01

This first edition of the New Media Consortium's (NMC) annual "Horizon Report" details findings of the Horizon Project, a research-oriented effort that seeks to identify and describe emerging technologies likely to have a large impact on teaching, learning, or creative expression within higher education. Drawing on an ongoing series of interviews…

78 FR 54298 - Horizons ETFs Management (USA) LLC and Horizons ETF Trust; Notice of Application

Federal Register 2010, 2011, 2012, 2013, 2014

2013-09-03

... SECURITIES AND EXCHANGE COMMISSION [Investment Company Act Release No. 30680; 812-14178] Horizons ETFs Management (USA) LLC and Horizons ETF Trust; Notice of Application August 27, 2013. AGENCY: Securities and Exchange Commission (``Commission''). ACTION: Notice of an application for an order under section 6(c) of the Investment Company Act of...

Gravitomagnetic Instabilities in Anisotropically Expanding Fluids

NASA Astrophysics Data System (ADS)

Kleidis, Kostas; Kuiroukidis, Apostolos; Papadopoulos, Demetrios B.; Vlahos, Loukas

Gravitational instabilities in a magnetized Friedman-Robertson-Walker (FRW) universe, in which the magnetic field was assumed to be too weak to destroy the isotropy of the model, are known and have been studied in the past. Accordingly, it became evident that the external magnetic field disfavors the perturbations' growth, suppressing the corresponding rate by an amount proportional to its strength. However, the spatial isotropy of the FRW universe is not compatible with the presence of large-scale magnetic fields. Therefore, in this paper we use the general-relativistic version of the (linearized) perturbed magnetohydrodynamic equations with and without resistivity, to discuss a generalized Jeans criterion and the potential formation of density condensations within a class of homogeneous and anisotropically expanding, self-gravitating, magnetized fluids in curved space-time. We find that, for a wide variety of anisotropic cosmological models, gravitomagnetic instabilities can lead to subhorizontal, magnetized condensations. In the nonresistive case, the power spectrum of the unstable cosmological perturbations suggests that most of the power is concentrated on large scales (small k), very close to the horizon. On the other hand, in a resistive medium, the critical wave-numbers so obtained, exhibit a delicate dependence on resistivity, resulting in the reduction of the corresponding Jeans lengths to smaller scales (well bellow the horizon) than the nonresistive ones, while increasing the range of cosmological models which admit such an instability.

Non-local geometry inside Lifshitz horizon

NASA Astrophysics Data System (ADS)

Hu, Qi; Lee, Sung-Sik

2017-07-01

Based on the quantum renormalization group, we derive the bulk geometry that emerges in the holographic dual of the fermionic U( N ) vector model at a nonzero charge density. The obstruction that prohibits the metallic state from being smoothly deformable to the direct product state under the renormalization group flow gives rise to a horizon at a finite radial coordinate in the bulk. The region outside the horizon is described by the Lifshitz geometry with a higher-spin hair determined by microscopic details of the boundary theory. On the other hand, the interior of the horizon is not described by any Riemannian manifold, as it exhibits an algebraic non-locality. The non-local structure inside the horizon carries the information on the shape of the filled Fermi sea.

Instability of enclosed horizons

NASA Astrophysics Data System (ADS)

Kay, Bernard S.

2015-03-01

We point out that there are solutions to the scalar wave equation on dimensional Minkowski space with finite energy tails which, if they reflect off a uniformly accelerated mirror due to (say) Dirichlet boundary conditions on it, develop an infinite stress-energy tensor on the mirror's Rindler horizon. We also show that, in the presence of an image mirror in the opposite Rindler wedge, suitable compactly supported arbitrarily small initial data on a suitable initial surface will develop an arbitrarily large stress-energy scalar near where the two horizons cross. Also, while there is a regular Hartle-Hawking-Israel-like state for the quantum theory between these two mirrors, there are coherent states built on it for which there are similar singularities in the expectation value of the renormalized stress-energy tensor. We conjecture that in other situations with analogous enclosed horizons such as a (maximally extended) Schwarzschild black hole in equilibrium in a (stationary spherical) box or the (maximally extended) Schwarzschild-AdS spacetime, there will be similar stress-energy singularities and almost-singularities—leading to instability of the horizons when gravity is switched on and matter and gravity perturbations are allowed for. All this suggests it is incorrect to picture a black hole in equilibrium in a box or a Schwarzschild-AdS black hole as extending beyond the past and future horizons of a single Schwarzschild (/Schwarzschild-AdS) wedge. It would thus provide new evidence for 't Hooft's brick wall model while seeming to invalidate the picture in Maldacena's ` Eternal black holes in AdS'. It would thereby also support the validity of the author's matter-gravity entanglement hypothesis and of the paper ` Brick walls and AdS/CFT' by the author and Ortíz.

Inspiring Young Hawaiian and Pacific Island Women to Pursue S.T.E.M. Careers: Expanding Your Horizons - Hawaii

NASA Astrophysics Data System (ADS)

Small Griswold, J. D.

2016-12-01

Expanding Your Horizons in Science and Mathematics (EYH) are conferences created to promote and foster interest for girls in the areas of science and math. The conferences are held with hopes that girls who attend will be encouraged to consider careers in these disciplines. Since 2014, the University of Hawaii at Mānoa (UH Mānoa) has held three annual EYH-Hawaii events reaching 86,163, and 150 girls respectively. EYH - Hawaii hosted 11 workshops in 2014, 22 in 2015, and 20 in 2016, primarily with atmospheric sciences, oceanography, marine biology, geology and physics related topics. The education outreach activities outlined in this work have far reaching societal implications. The lack of women in the sciences has been a problem for over 50 years and Native Hawaiian and Pacific Islanders represent an event smaller fraction of women in science. It has been shown that mentoring programs, especially those focused on STEM fields, help young women and girls to envision themselves as chemists, physicists, mathematicians and other types of scientists such as those that study the earth and atmosphere which are fields that are not commonly discussed or highlighted in K-12 curriculum. EYH and related conferences for young women increase the likelihood that they will pursue science and math in secondary educational settings. This is essential in a world in which few girls are choosing science and math as potential careers. Here we compile survey results from the three EYH - Hawaii events to determine trends in attendance, interest, and overall impact. Each year attendees were surveyed regarding their overall experience at the conference, individual workshop experience, and personal demographic information. We especially highlight statistics related to the experience of students of Native Hawaiian and Pacific Island descent. Survey results discussed include: grade level, ethnicity/race, hometown, favorite and least favorite aspect and/or workshop of the conference

Across-horizon scattering and information transfer

NASA Astrophysics Data System (ADS)

Emelyanov, V. A.; Klinkhamer, F. R.

2018-06-01

We address the question whether or not two electrically charged elementary particles can Coulomb scatter if one of these particles is inside the Schwarzschild black-hole horizon and the other outside. It can be shown that the quantum process is consistent with the local energy–momentum conservation law. This result implies that across-horizon scattering is a physical effect, relevant to astrophysical black holes. We propose a Gedankenexperiment which uses the quantum scattering process to transfer information from inside the black-hole horizon to outside.

Classification of Near-Horizon Geometries of Extremal Black Holes.

PubMed

Kunduri, Hari K; Lucietti, James

2013-01-01

Any spacetime containing a degenerate Killing horizon, such as an extremal black hole, possesses a well-defined notion of a near-horizon geometry. We review such near-horizon geometry solutions in a variety of dimensions and theories in a unified manner. We discuss various general results including horizon topology and near-horizon symmetry enhancement. We also discuss the status of the classification of near-horizon geometries in theories ranging from vacuum gravity to Einstein-Maxwell theory and supergravity theories. Finally, we discuss applications to the classification of extremal black holes and various related topics. Several new results are presented and open problems are highlighted throughout.

Horizon state, Hawking radiation, and boundary Liouville model.

PubMed

Solodukhin, Sergey N

2004-02-13

We demonstrate that the near-horizon physics, the Hawking radiation, and the reflection off the radial potential barrier can be understood entirely within a conformal field theory picture in terms of one- and two-point functions in the boundary Liouville theory. An important element in this demonstration is the notion of horizon state, the Hawking radiation being interpreted as a result of the transition of horizon state to the ordinary states propagating outside the black hole horizon.

Gravitational memory charges of supertranslation and superrotation on Rindler horizons

NASA Astrophysics Data System (ADS)

Hotta, Masahiro; Trevison, Jose; Yamaguchi, Koji

2016-10-01

In a Rindler-type coordinate system spanned in a region outside of a black hole horizon, we have nonvanishing classical holographic charges as soft hairs on the horizon for stationary black holes. Taking a large black hole mass limit, the spacetimes with the charges are described by asymptotic Rindler metrics. We construct a general theory of gravitational holographic charges for a (1 +3 )-dimensional linearized gravity field in the Minkowski background with Rindler horizons. Although matter crossing a Rindler horizon causes horizon deformation and a time-dependent coordinate shift—that is, gravitational memory—the supertranslation and superrotation charges on the horizon can be defined during and after its passage through the horizon. It is generally proven that holographic states on the horizon cannot store any information about absorbed perturbative gravitational waves. However, matter crossing the horizon really excites holographic states. By using gravitational memory operators, which consist of the holographic charge operators, we suggest a resolution of the no-cloning paradox of quantum information between matter falling into the horizon and holographic charges on the horizon from the viewpoint of the contextuality of quantum measurement.

Avoiding Intellectual Stagnation: The Starship as an Expander of Minds

NASA Astrophysics Data System (ADS)

Crawford, Ian A.

2014-06-01

Interstellar exploration will advance human knowledge and culture in multiple ways. Scientifically, it will advance our understanding of the interstellar medium, stellar astrophysics, planetary science and astrobiology. In addition, significant societal and cultural benefits will result from a programme of interstellar exploration and colonisation. Most important will be the cultural stimuli resulting from expanding the horizons of human experience, and increased opportunities for the spread and diversification of life and culture through the Galaxy. Ultimately, a programme of interstellar exploration may be the only way for human (and post-human) societies to avoid the intellectual stagnation predicted for the `end of history'.

Star-Paths, Stones and Horizon Astronomy

NASA Astrophysics Data System (ADS)

Brady, Bernadette

2015-05-01

Archaeoastronomers tend to approach ancient monuments focusing on the landscape and the horizon calendar events of sun and moon and, due to problems with precession, generally ignore the movement of the stars. However, locating the position of solar calendar points on the horizon can have other uses apart from calendar and/or cosmological purposes. This paper firstly suggests that the stars do not need to be ignored. By considering the evidence of the Phaenomena, a sky poem by Aratus of Soli, a third century BC Greek poet, and his use of second millennium BC star lore fragments, this paper argues that the stars were a part of the knowledge of horizon astronomy. Aratus' poem implied that the horizon astronomy of the late Neolithic and Bronze Age periods included knowledge of star-paths or 'linear constellations' that were defined by particular horizon calendar events and other azimuths. Knowledge of such star-paths would have enabled navigation and orientation, and by using permanent markers, constructed or natural, to define these paths, they were immune to precession as the stones could redefine a star-path for a future generation. Finally the paper presents other possible intentions behind the diverse orientation of passage tombs and some megalithic sites.

Horizon as critical phenomenon

NASA Astrophysics Data System (ADS)

Lee, Sung-Sik

2016-09-01

We show that renormalization group flow can be viewed as a gradual wave function collapse, where a quantum state associated with the action of field theory evolves toward a final state that describes an IR fixed point. The process of collapse is described by the radial evolution in the dual holographic theory. If the theory is in the same phase as the assumed IR fixed point, the initial state is smoothly projected to the final state. If in a different phase, the initial state undergoes a phase transition which in turn gives rise to a horizon in the bulk geometry. We demonstrate the connection between critical behavior and horizon in an example, by deriving the bulk metrics that emerge in various phases of the U( N ) vector model in the large N limit based on the holographic dual constructed from quantum renormalization group. The gapped phase exhibits a geometry that smoothly ends at a finite proper distance in the radial direction. The geometric distance in the radial direction measures a complexity: the depth of renormalization group transformation that is needed to project the generally entangled UV state to a direct product state in the IR. For gapless states, entanglement persistently spreads out to larger length scales, and the initial state can not be projected to the direct product state. The obstruction to smooth projection at charge neutral point manifests itself as the long throat in the anti-de Sitter space. The Poincare horizon at infinity marks the critical point which exhibits a divergent length scale in the spread of entanglement. For the gapless states with non-zero chemical potential, the bulk space becomes the Lifshitz geometry with the dynamical critical exponent two. The identification of horizon as critical point may provide an explanation for the universality of horizon. We also discuss the structure of the bulk tensor network that emerges from the quantum renormalization group.

Theory underlying the peripheral vision horizon device

NASA Technical Reports Server (NTRS)

Money, K. E.

1984-01-01

Peripheral Vision Horizon Device (PVHD) theory states that the likelihood of pilot disorientation in flight is reduced by providing an artificial horizon that provides orientation information to peripheral vision. In considering the validity of the theory, three areas are explored: the use of an artificial horizon device over some other flight instrument; the use of peripheral vision over foveal vision; and the evidence that peripheral vision is well suited to the processing of orientation information.

Nonlinear optics of fibre event horizons.

PubMed

Webb, Karen E; Erkintalo, Miro; Xu, Yiqing; Broderick, Neil G R; Dudley, John M; Genty, Goëry; Murdoch, Stuart G

2014-09-17

The nonlinear interaction of light in an optical fibre can mimic the physics at an event horizon. This analogue arises when a weak probe wave is unable to pass through an intense soliton, despite propagating at a different velocity. To date, these dynamics have been described in the time domain in terms of a soliton-induced refractive index barrier that modifies the velocity of the probe. Here we complete the physical description of fibre-optic event horizons by presenting a full frequency-domain description in terms of cascaded four-wave mixing between discrete single-frequency fields, and experimentally demonstrate signature frequency shifts using continuous wave lasers. Our description is confirmed by the remarkable agreement with experiments performed in the continuum limit, reached using ultrafast lasers. We anticipate that clarifying the description of fibre event horizons will significantly impact on the description of horizon dynamics and soliton interactions in photonics and other systems.

Into the Kuiper Belt: New Horizons Post-Pluto

NASA Astrophysics Data System (ADS)

Harrison Parker, Alex; Spencer, John; Benecchi, Susan; Binzel, Richard; Borncamp, David; Buie, Marc; Fuentes, Cesar; Gwyn, Stephen; Kavelaars, JJ; Noll, Keith; Petit, Jean-Marc; Porter, Simon; Showalter, Mark; Stern, S. Alan; Sterner, Ray; Tholen, David; Verbiscer, Anne; Weaver, Hal; Zangari, Amanda

2015-11-01

New Horizons is now beyond Pluto and flying deeper into the Kuiper Belt. In the summer of 2014, a Hubble Space Telescope Large Program identified two candidate Cold Classical Kuiper Belt Objects (KBOs) that were within reach of New Horizons' remaining fuel budget. Here we present the selection of the Kuiper Belt flyby target for New Horizons' post-Pluto mission, our state of knowledge regarding this target and the potential 2019 flyby, the status of New Horizons' targeting maneuver, and prospects for near-future long-range observations of other KBOs.

Earth's horizon

NASA Image and Video Library

2005-07-30

S114-E-6076 (30 July 2005) --- The blackness of space and Earth’s horizon form the backdrop for this view of the extended Space Shuttle Discovery’s remote manipulator system (RMS) robotic arm while docked to the International Space Station during the STS-114 mission.

Inside out: meet the operators inside the horizon. On bulk reconstruction behind causal horizons

NASA Astrophysics Data System (ADS)

Almheiri, Ahmed; Anous, Tarek; Lewkowycz, Aitor

2018-01-01

Based on the work of Heemskerk, Marolf, Polchinski and Sully (HMPS), we study the reconstruction of operators behind causal horizons in time dependent geometries obtained by acting with shockwaves on pure states or thermal states. These geometries admit a natural basis of gauge invariant operators, namely those geodesically dressed to the boundary along geodesics which emanate from the bifurcate horizon at constant Rindler time. We outline a procedure for obtaining operators behind the causal horizon but inside the entanglement wedge by exploiting the equality between bulk and boundary time evolution, as well as the freedom to consider the operators evolved by distinct Hamiltonians. This requires we carefully keep track of how the operators are gravitationally dressed and that we address issues regarding background dependence. We compare this procedure to reconstruction using modular flow, and illustrate some formal points in simple cases such as AdS2 and AdS3.

Microbiomes structure and diversity in different horizons of full soil profiles

NASA Astrophysics Data System (ADS)

Chernov, Timofey; Tkhakakhova, Azida; Zhelezova, Alena; Semenov, Mikhail; Kutovaya, Olga

2017-04-01

Topsoil is a most common object for soil metagenomic studies; sometimes soil profile is being formally split in layers by depth. However, Russian Soil Science School formulated the idea of soil profile as a complex of soil horizons, which can differ in their properties and genesis. In this research we analyzed 57 genetic soil horizons of 8 different soils from European part of Russia: Albeluvisol, Greyzemic Phaeozem, three Chermozems (different land use - till, fallow, wind-protecting tree line), Rhodic Cambisol, Haplic Kastanozem and Salic Solonetz (WRB classification). Sampling was performed from all genetic horizons in each soil profile starting from topsoil until subsoil. Total DNA was extracted and 16S rRNA sequencing was provided together with chemical analysis of soil (pH measurement, C and N contents, etc.). Structure and diversity of prokaryotic community are significantly different in those soil horizons, which chemical properties and processes of origin are contrasting with nearest horizons: Na-enriched horizon of Solonetz, eluvial horizon of Albeluvisol, plough pan of Agrochernozem. Actinobacteria were abundant in top horizons of soils in warm and dry climate, while Acidobacteria had the highest frequency in soils of moist and cold regions. Concerning Archaea, Thaumarchaeota prevailed in all studied soils. Their rate was higher in microbiomes of upper horizons of steppe soils and it was reducing with depth down the profile. Prokaryotic communities in Chernozems were clustered by soil horizons types: microbiomes of A (organic topsoil) and B (mineral) horizons formed non-overlapping clusters by principal component analysis, cluster formed by prokaryotic communities of transitional soil horizons (AB) take place between clusters of A and B horizons. Moreover, prokaryotic communities of A horizons differ from each other strongly, while microbiomes of B horizons formed a narrow small cluster. It must be explaned by more diverse conditions in upper A horizons

The Horizon Report: 2010 Museum Edition

ERIC Educational Resources Information Center

Johnson, L.; Witchey, H.; Smith, R.; Levine, A.; Haywood, K.

2010-01-01

The internationally recognized series of "Horizon Reports" is part of the New Media Consortium's Horizon Project, a comprehensive research venture established in 2002 that identifies and describes emerging technologies likely to have a large impact over the coming five years on a variety of sectors around the globe. This volume, the "2010 Horizon…

Horizon Report: 2010 K-12 Edition

ERIC Educational Resources Information Center

Johnson, L.; Smith, R.; Levine, A.; Haywood, K.

2010-01-01

The "Horizon Report" series is the most visible outcome of the New Media Consortium's Horizon Project, an ongoing research effort established in 2002 that identifies and describes emerging technologies likely to have a large impact on teaching, learning, research, or creative expression within education around the globe. This volume, the "2010…

Robust real-time horizon detection in full-motion video

NASA Astrophysics Data System (ADS)

Young, Grace B.; Bagnall, Bryan; Lane, Corey; Parameswaran, Shibin

2014-06-01

The ability to detect the horizon on a real-time basis in full-motion video is an important capability to aid and facilitate real-time processing of full-motion videos for the purposes such as object detection, recognition and other video/image segmentation applications. In this paper, we propose a method for real-time horizon detection that is designed to be used as a front-end processing unit for a real-time marine object detection system that carries out object detection and tracking on full-motion videos captured by ship/harbor-mounted cameras, Unmanned Aerial Vehicles (UAVs) or any other method of surveillance for Maritime Domain Awareness (MDA). Unlike existing horizon detection work, we cannot assume a priori the angle or nature (for e.g. straight line) of the horizon, due to the nature of the application domain and the data. Therefore, the proposed real-time algorithm is designed to identify the horizon at any angle and irrespective of objects appearing close to and/or occluding the horizon line (for e.g. trees, vehicles at a distance) by accounting for its non-linear nature. We use a simple two-stage hierarchical methodology, leveraging color-based features, to quickly isolate the region of the image containing the horizon and then perform a more ne-grained horizon detection operation. In this paper, we present our real-time horizon detection results using our algorithm on real-world full-motion video data from a variety of surveillance sensors like UAVs and ship mounted cameras con rming the real-time applicability of this method and its ability to detect horizon with no a priori assumptions.

Generalized Robertson-Walker Space-Time Admitting Evolving Null Horizons Related to a Black Hole Event Horizon

PubMed Central

2016-01-01

A new technique is used to study a family of time-dependent null horizons, called “Evolving Null Horizons” (ENHs), of generalized Robertson-Walker (GRW) space-time (M¯,g¯) such that the metric g¯ satisfies a kinematic condition. This work is different from our early papers on the same issue where we used (1 + n)-splitting space-time but only some special subcases of GRW space-time have this formalism. Also, in contrast to previous work, we have proved that each member of ENHs is totally umbilical in (M¯,g¯). Finally, we show that there exists an ENH which is always a null horizon evolving into a black hole event horizon and suggest some open problems. PMID:27722202

Horizon Report: 2009 Economic Development Edition

ERIC Educational Resources Information Center

Johnson, L.; Levine, A.; Scott, C.; Smith, R.; Stone, S.

2009-01-01

The New Media Consortium's Horizon Project is an ongoing research project that seeks to identify and describe emerging technologies likely to have a large impact in education and other industries around the world over a five-year time period. The chief products of the project are the "Horizon Reports", an annual series of publications…

The influence of time horizon on results of cost-effectiveness analyses.

PubMed

Kim, David D; Wilkinson, Colby L; Pope, Elle F; Chambers, James D; Cohen, Joshua T; Neumann, Peter J

2017-12-01

Debates persist on the appropriate time horizon from a payer's perspective and how the time horizon in cost-effectiveness analysis (CEA) influences the value assessment. We systematically reviewed the Tufts Medical Center CEA Registry and identified US-based studies that used a payer perspective from 2005-2014. We classified the identified CEAs as short-term (time horizon ≤ 5 years) and long-term (> 5 years), and examined associations between study characteristics and the specified time horizon. We also developed case studies with selected interventions to further explore the relationship between time horizon and projected costs, benefits, and incremental cost-effectiveness ratios (ICER). Among 782 identified studies that met our inclusion criteria, 552 studies (71%) utilized a long-term time horizon while 198 studies (25%) used a short-term horizon. Among studies that employed multiple time horizons, the extension of the time horizon yielded more favorable ICERs in 19 cases and less favorable ICERs in 4 cases. Case studies showed the use of a longer time horizon also yielded more favorable ICERs. The assumed time horizon in CEAs can substantially influence the value assessment of medical interventions. To capture all consequences, we encourage the use of time horizons that extend sufficiently into the future.

Quantum theory of charged isolated horizons

NASA Astrophysics Data System (ADS)

Eder, Konstantin; Sahlmann, Hanno

2018-04-01

We describe the quantum theory of isolated horizons with electromagnetic or non-Abelian gauge charges in a setting in which both the gauge and gravitational field are quantized. We consider the distorted case, and its spherically symmetric limit. We show that the gravitational horizon d.o.f. give rise to the Bekenstein-Hawking relation, with lower-order terms giving some corrections for small black holes. We also demonstrate that one can include matter d.o.f. in the state counting. We show that one can expect (potentially divergent) contributions proportional to the area, as well as logarithmic corrections proportional to the horizon charge. This is qualitatively similar to results on matter contributions obtained with other methods in the literature.

Quantum-corrected Geometry of Horizon Vicinity

NASA Astrophysics Data System (ADS)

Park, I. Y.

2017-12-01

We study the deformation of the horizon-vicinity geometry caused by quantum gravitational effects. Departure from the semi-classical picture is noted, and the fact that the matter part of the action comes at a higher order in Newton's constant than does the Einstein-Hilbert term is crucial for the departure. The analysis leads to a Firewall-type energy measured by an infalling observer for which quantum generation of the cosmological constant is critical. The analysis seems to suggest that the Firewall should be a part of such deformation and that the information be stored both in the horizon-vicinity and asymptotic boundary region. We also examine the behavior near the cosmological horizon.

Numerical implementation of isolated horizon boundary conditions

NASA Astrophysics Data System (ADS)

Jaramillo, José Luis; Ansorg, Marcus; Limousin, François

2007-01-01

We study the numerical implementation of a set of boundary conditions derived from the isolated horizon formalism, and which characterize a black hole whose horizon is in quasiequilibrium. More precisely, we enforce these geometrical prescriptions as inner boundary conditions on an excised sphere, in the numerical resolution of the conformal thin sandwich equations. As main results, we first establish the consistency of including in the set of boundary conditions a constant surface gravity prescription, interpretable as a lapse boundary condition, and second we assess how the prescriptions presented recently by Dain et al. for guaranteeing the well-posedness of the conformal transverse traceless equations with quasiequilibrium horizon conditions extend to the conformal thin sandwich elliptic system. As a consequence of the latter analysis, we discuss the freedom of prescribing the expansion associated with the ingoing null normal at the horizon.

The New Horizons Kuiper Belt Extended Mission

NASA Astrophysics Data System (ADS)

Stern, S. A.; Weaver, H. A.; Spencer, J. R.; Elliott, H. A.

2018-06-01

The central objective of the New Horizons prime mission was to make the first exploration of Pluto and its system of moons. Following that, New Horizons has been approved for its first extended mission, which has the objectives of extensively studying the Kuiper Belt environment, observing numerous Kuiper Belt Objects (KBOs) and Centaurs in unique ways, and making the first close flyby of the KBO 486958 2014 MU69. This review summarizes the objectives and plans for this approved mission extension, and briefly looks forward to potential objectives for subsequent extended missions by New Horizons.

Feasibility of using bulk metallic glass for self-expandable stent applications.

PubMed

Praveen Kumar, Gideon; Jafary-Zadeh, Mehdi; Tavakoli, Rouhollah; Cui, Fangsen

2017-10-01

Self-expandable stents are widely used to restore blood flow in a diseased artery segment by keeping the artery open after angioplasty. Despite the prevalent use of conventional crystalline metallic alloys, for example, nitinol, to construct self-expandable stents, new biomaterials such as bulk metallic glasses (BMGs) are being actively pursued to improve stent performance. Here, we conducted a series of analyses including finite element analysis and molecular dynamics simulations to investigate the feasibility of using a prototypical Zr-based BMG for self-expandable stent applications. We model stent crimping of several designs for different percutaneous applications. Our results indicate that BMG-based stents with diamond-shaped crowns suffer from severe localization of plastic deformation and abrupt failure during crimping. As a possible solution, we further illustrate that such abrupt failure could be avoided in BMG-based stents without diamond shape crowns. This work would open a new horizon for a quest toward exploiting superior mechanical and functional properties of metallic glasses to design future stents. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 1874-1882, 2017. © 2016 Wiley Periodicals, Inc.

Plasmonic Horizon in Gold Nanosponges.

PubMed

Vidal, Cynthia; Sivun, Dmitry; Ziegler, Johannes; Wang, Dong; Schaaf, Peter; Hrelescu, Calin; Klar, Thomas A

2018-02-14

An electromagnetic wave impinging on a gold nanosponge coherently excites many electromagnetic hot-spots inside the nanosponge, yielding a polarization-dependent scattering spectrum. In contrast, a hole, recombining with an electron, can locally excite plasmonic hot-spots only within a horizon given by the lifetime of localized plasmons and the speed carrying the information that a plasmon has been created. This horizon is about 57 nm, decreasing with increasing size of the nanosponge. Consequently, photoluminescence from large gold nanosponges appears unpolarized.

Horizon Detection In The Visible Spectrum

DTIC Science & Technology

2016-09-01

techniques can also recognize star patterns in star trackers for satellite attitude determination. Horizon detection in the visible spectrum was largely...discarded for attitude determination in favor of thermal imagery, due to the greater consistency of the earth’s thermal radiation. This thesis...in 85% of the tested image set. 14. SUBJECT TERMS attitude determination, machine learning, image classification, earth horizon sensor, computer

Numerical implementation of isolated horizon boundary conditions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jaramillo, Jose Luis; Ansorg, Marcus; Limousin, Francois

2007-01-15

We study the numerical implementation of a set of boundary conditions derived from the isolated horizon formalism, and which characterize a black hole whose horizon is in quasiequilibrium. More precisely, we enforce these geometrical prescriptions as inner boundary conditions on an excised sphere, in the numerical resolution of the conformal thin sandwich equations. As main results, we first establish the consistency of including in the set of boundary conditions a constant surface gravity prescription, interpretable as a lapse boundary condition, and second we assess how the prescriptions presented recently by Dain et al. for guaranteeing the well-posedness of the conformalmore » transverse traceless equations with quasiequilibrium horizon conditions extend to the conformal thin sandwich elliptic system. As a consequence of the latter analysis, we discuss the freedom of prescribing the expansion associated with the ingoing null normal at the horizon.« less

New Horizons Very Best View of Pluto

NASA Image and Video Library

2015-12-05

This frame from a movie is composed of the sharpest views of Pluto that NASA's New Horizons spacecraft obtained during its flyby of the distant planet on July 14, 2015. The pictures are part of a sequence taken near New Horizons' closest approach to Pluto, with resolutions of about 250-280 feet (77-85 meters) per pixel -- revealing features smaller than half a city block on Pluto's diverse surface. The images include a wide variety of spectacular, cratered, mountainous and glacial terrains -- giving scientists and the public alike a breathtaking, super-high resolution window on Pluto's geology. The images form a strip 50 miles (80 kilometers) wide trending from Pluto's jagged horizon about 500 miles (800 kilometers) northwest of the informally named Sputnik Planum, across the al-Idrisi mountains, onto the shoreline of Sputnik Planum and then across its icy plains. They were made with the telescopic Long Range Reconnaissance Imager (LORRI) aboard New Horizons, over a timespan of about a minute centered on 11:36 UT on July 14 -- just about 15 minutes before New Horizons' closest approach to Pluto -- from a range of just 10,000 miles (17,000 kilometers). They were obtained with an unusual observing mode; instead of working in the usual "point and shoot," LORRI snapped pictures every three seconds while the Ralph/Multispectral Visual Imaging Camera (MVIC) aboard New Horizons was scanning the surface. This mode requires unusually short exposures to avoid blurring the images. http://photojournal.jpl.nasa.gov/catalog/PIA20202

Deepwater Horizon Situation Report #5

DOE Office of Scientific and Technical Information (OSTI.GOV)

None

2010-06-10

At approximately 11:00 pm EDT April 20, 2010 an explosion occurred aboard the Deepwater Horizon mobile offshore drilling unit (MODU) located 52 miles Southeast of Venice, LA and 130 miles southeast of New Orleans, LA. The MODU was drilling an exploratory well and was not producing oil at the time of the incident. The Deepwater Horizon MODU sank 1,500 feet northwest of the well site. Detailed information on response and recovery operations can be found at: http://www.deepwaterhorizonresponse.com/go/site/2931/

Horizon photo of Western horizon over South America - sixth orbit pass

NASA Image and Video Library

1962-10-03

S62-06604 (3 Oct. 1962) --- Western horizon over South America taken during the sixth orbit pass of the Mercury-Atlas 8 (MA-8) mission by astronaut Walter M. Schirra Jr. with a hand-held camera. Photo credit: NASA

Horizon photo of Western horizon over South America - sixth orbit pass

NASA Image and Video Library

1962-10-03

S62-06607 (3 Oct. 1962) --- Western horizon over South America taken during the sixth orbit pass of the Mercury-Atlas 8 (MA-8) mission by astronaut Walter M. Schirra Jr. with a hand-held camera. Photo credit: NASA

An Educational Look at an alternative to the Expanding Universe Model

NASA Astrophysics Data System (ADS)

Kriske, Richard

2009-11-01

The author often toys with an alternative view to the expanding universe model and believes it would be a good way to teach the Scientific method. In the author's (R.M. Kriske) model the red shift is a result of magnifying the horizon of a 4 dimensional surface. On a two dimensional surface such as the earth the horizon is not maginifiable since things on the surface naturally tilt away from the observer in every direction and everything is transformed into a curved line (the Horizon) (the students can verify this as a globe can be used with some pins in it-for example). Likewise one would expect this signature of curvature to show up on three curved space dimensions, and instead of pins, a perpendicular time dimension. As the observer looks toward the pins they tilt away from him/her and in four dimensions this means they are accelerating away from him/her even though the globe is standing still. At each point a pair is being produced with its attendant gamma ray emission, but the points are of course seen as accelerating away, simply due to the curvature of the globe and nothing else, resulting in a red shift. This author produced model has never been suggested before and never presented to the Scientific community. The students would then need to compare this to the current simpler model that point sources accelerating away from the observer undergo a redshift due to the Doppler Effect. The Students would then have to review these models and determine the size of the globe for the amount of red shift seen from the two competing models. One model has a cut- off mode, since the pins not only tip backward in the curved space model but are also cut off. How does this cut-off show up, is it simply dimming, and can an experiment be done for it? The last step of this exercise is to see if one could tell the difference between these models, and if a mixed model is better, since the Globe could also be expanding (Of course the instructor could also ask what the result

The absence of horizon in black-hole formation

NASA Astrophysics Data System (ADS)

Ho, Pei-Ming

2016-08-01

With the back-reaction of Hawking radiation taken into consideration, the work of Kawai, Matsuo and Yokokura [1] has shown that, under a few assumptions, the collapse of matter does not lead to event horizon nor apparent horizon. In this paper, we relax their assumptions and elaborate on the space-time geometry of a generic collapsing body with spherical symmetry. The geometry outside the collapsing sphere is found to be approximated by the geometry outside the white-hole horizon, hence the collapsing matter remains outside the Schwarzschild radius. As particles in Hawking radiation are created in the vicinity of the collapsing matter, the information loss paradox is alleviated. Assuming that the collapsing body evaporates within finite time, there is no event horizon.

What happens to Petrov classification, on horizons of axisymmetric dirty black holes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tanatarov, I. V., E-mail: igor.tanatarov@gmail.com; Department of Physics and Technology, Kharkov V.N. Karazin National University, 4 Svoboda Square, Kharkov 61077; Zaslavskii, O. B., E-mail: zaslav@ukr.net

2014-02-15

We consider axisymmetric stationary dirty black holes with regular non-extremal or extremal horizons, and compute their on-horizon Petrov types. The Petrov type (PT) in the frame of the observer crossing the horizon can be different from that formally obtained in the usual (but singular in the horizon limit) frame of an observer on a circular orbit. We call this entity the boosted Petrov type (BPT), as the corresponding frame is obtained by a singular boost from the regular one. The PT off-horizon can be more general than PT on-horizon and that can be more general than the BPT on horizon.more » This is valid for all regular metrics, irrespective of the extremality of the horizon. We analyze and classify the possible relations between the three characteristics and discuss the nature and features of the underlying singular boost. The three Petrov types can be the same only for space-times of PT D and O off-horizon. The mutual alignment of principal null directions and the generator in the vicinity of the horizon is studied in detail. As an example, we also analyze a special class of metrics with utra-extremal horizons (for which the regularity conditions look different from the general case) and compare their off-horizon and on-horizon algebraic structure in both frames.« less

Observations of the Geometry of Horizon-Based Optical Navigation

NASA Technical Reports Server (NTRS)

Christian, John; Robinson, Shane

2016-01-01

NASA's Orion Project has sparked a renewed interest in horizon-based optical navigation(OPNAV) techniques for spacecraft in the Earth-Moon system. Some approaches have begun to explore the geometry of horizon-based OPNAV and exploit the fact that it is a conic section problem. Therefore, the present paper focuses more deeply on understanding and leveraging the various geometric interpretations of horizon-based OPNAV. These results provide valuable insight into the fundamental workings of OPNAV solution methods, their convergence properties, and associated estimate covariance. Most importantly, the geometry and transformations uncovered in this paper lead to a simple and non-iterative solution to the generic horizon-based OPNAV problem. This represents a significant theoretical advancement over existing methods. Thus, we find that a clear understanding of geometric relationships is central to the prudent design, use, and operation of horizon-based OPNAV techniques.

Dynamical symmetry enhancement near N = 2, D = 4 gauged supergravity horizons

NASA Astrophysics Data System (ADS)

Gutowski, J.; Mohaupt, T.; Papadopoulos, G.

2017-03-01

We show that all smooth Killing horizons with compact horizon sections of 4-dimensional gauged N = 2 supergravity coupled to any number of vector multiplets preserve 2{c}_1(K)+4ℓ supersymmetries, where K is a pull-back of the Hodge bundle of the special Kähler manifold on the horizon spatial section. We also demonstrate that all such horizons with {c}_1(K)=0 exhibit an sl(2,R) symmetry and preserve either 4 or 8 supersymmetries. If the orbits of the sl(2,R) symmetry are 2-dimensional, the horizons are warped products of AdS2 with the horizon spatial section. Otherwise, the horizon section admits an isometry which preserves all the fields. The proof of these results is centered on the use of index theorem in conjunction with an appropriate generalization of the Lichnerowicz theorem for horizons that preserve at least one supersymmetry. In all {c}_1(K)=0 cases, we specify the local geometry of spatial horizon sections and demonstrate that the solutions are determined by first order non-linear ordinary differential equations on some of the fields.

Leadership Online: Expanding the Horizon

ERIC Educational Resources Information Center

Phelps, Kirstin

2012-01-01

With an increase of online teaching, social media, and use of classroom technology by both location-bound and distance students, how do educators teach and learn leadership through online tools? The International Leadership Association (ILA, 2009) guidelines, specifically the overarching questions for teaching and learning, provide direction in…

The NMC Horizon Report: 2014 Library Edition

ERIC Educational Resources Information Center

Johnson, L.; Adams Becker, S.; Estrada, V.; Freeman, A.

2014-01-01

The internationally recognized "NMC Horizon Report" series and regional "NMC Technology Outlooks" are part of the NMC Horizon Project, a 12-year effort established in 2002 that annually identifies and describes emerging technologies likely to have a large impact over the coming five years in every sector of education around the…

The NMC Horizon Report: 2015 Museum Edition

ERIC Educational Resources Information Center

Johnson, L.; Adams Becker, S.; Estrada, V.; Freeman, A.

2015-01-01

The internationally recognized series of "Horizon Reports" is part of the New Media Consortium's Horizon Project, a comprehensive research venture established in 2002 that identifies and describes emerging technologies likely to have a large impact over the coming years on a variety of sectors around the globe. This "2015 Horizon…

Horizon Based Orientation Estimation for Planetary Surface Navigation

NASA Technical Reports Server (NTRS)

Bouyssounouse, X.; Nefian, A. V.; Deans, M.; Thomas, A.; Edwards, L.; Fong, T.

2016-01-01

Planetary rovers navigate in extreme environments for which a Global Positioning System (GPS) is unavailable, maps are restricted to relatively low resolution provided by orbital imagery, and compass information is often lacking due to weak or not existent magnetic fields. However, an accurate rover localization is particularly important to achieve the mission success by reaching the science targets, avoiding negative obstacles visible only in orbital maps, and maintaining good communication connections with ground. This paper describes a horizon solution for precise rover orientation estimation. The detected horizon in imagery provided by the on board navigation cameras is matched with the horizon rendered over the existing terrain model. The set of rotation parameters (roll, pitch yaw) that minimize the cost function between the two horizon curves corresponds to the rover estimated pose.

The pedogeochemical segregation a few horizons in soils from glass houses

NASA Astrophysics Data System (ADS)

Bulgariu, Dumitru; Rusu, Constantin; Filipov, Feodor; Buzgar, Nicolae; Bulgariu, Laura

2010-05-01

Our studies have focused the apparition and manifestation conditions of pedogeochemical segregation phenomena in case of soils from Copou - Iaşi, Bacău and Bârlad (Romania) glass house, and the effects of this on the pedogeochemical and agrochemical characteristics of soils from glass houses cultivated with vegetables. The utilization of intensive cultivation technologies of vegetables in glass houses determined the degradation of morphological, physical and chemical characteristics of soils, by rapid evolution of salted processes (salinization and / or sodization), compaction, carbonatation, eluviation-illuviation, frangipane formation, stagnogleization, gleization etc. Under these conditions, at depth of 30-40 cm is formed a compact and impenetrable horizon - Ahok(x) horizon. In function of exploitation conditions and by the chemical-mineralogical characteristics of soils from glasshouses, the Ahok horizons can have frangipane properties, expressed more or less. These horizons determined a geochemical segregation of soils from glass houses: (i) superior horizons, above Ahok(x) horizon evolve in weak oxidative conditions, weak alkaline pH, higher salinity, humidity and temperature; (ii) inferior horizons, below Ahok(x) horizon evolve in weak reducing conditions weak acid pH, lower salinity, humidity and temperature. Concomitant with the development of Ahok(x) horizons, the rapid degradation of the properties of soils from glasshouses is observed. The aspects about the formation of frangipane horizon in soils from glasshouses are not yet sufficiently know. Whatever of the formation processes, the frangipane horizons determined a sever segregation in pedogeochemical evolution of soils from glass houses, with very important consequences on the agrochemical quality of these soils. The segregation effects are manifested in the differential dynamics of pedogeochemical processes from superior horizons (situated above the segregation horizon), in comparison with the

Scanning the horizon in a decentralized healthcare system: the Canadian experience.

PubMed

Morrison, Andra

2012-07-01

Canada has a highly decentralized health care system with 13 provinces and territories delivering health care within their own respective jurisdictions. Decisions regarding which innovative health technologies to adopt are often driven by the unique health care priorities of each jurisdiction's population. To understand these needs, the Canadian Agency for Drugs and Technologies in Health's (CADTH's) Early Awareness Service has expanded its activities. In addition to proactively scanning the horizon for new and emerging health technologies, the Early Awareness Service also scans the horizon for national and jurisdictional health policy issues. This paper looks at CADTH's process for identifying and monitoring policy issues at a national and jurisdictional level. CADTH's Early Awareness Service delivers timely information on emerging health care concerns and technologies that may affect health care finances, facilities, operations, and patient care. The identification of important policy issues can help determine which new and emerging technologies will have the most significant impact on the health care system. The information that CADTH scans can also be used to help decision-makers prepare for potential developments and events that may have an impact on health care systems. By improving its capability to identify and share policy issues across and within jurisdictions, CADTH is better situated to provide information that can be used by policy-makers to help them plan and anticipate for the introduction of new technologies and future developments affecting the unique health care needs of their jurisdictions.

A presomite human embryo of Horizon VII.

PubMed Central

Rewell, R E; Harrison, R G

1976-01-01

A presomite embryo of Horizon VII aged approximately 18 days is described and illustrated. It is compared with some other embryos of a similar age, and a considerable variation of histological characteristics within the same Horizon is noted. Images Fig. 1 Fig. 2 Fig. 3 Fig. 4 Fig. 5 Fig. 6 Fig. 7 PMID:1254532

New Horizons Very Best View of Pluto Mosiac

NASA Image and Video Library

2015-12-05

This mosaic is composed of the sharpest views of Pluto that NASA's New Horizons spacecraft obtained during its flyby of the distant planet on July 14, 2015. The pictures are part of a sequence taken near New Horizons' closest approach to Pluto, with resolutions of about 250-280 feet (77-85 meters) per pixel -- revealing features smaller than half a city block on Pluto's diverse surface. The images include a wide variety of spectacular, cratered, mountainous and glacial terrains -- giving scientists and the public alike a breathtaking, super-high resolution window on Pluto's geology. The images form a strip 50 miles (80 kilometers) wide trending from Pluto's jagged horizon about 500 miles (800 kilometers) northwest of the informally named Sputnik Planum, across the al-Idrisi mountains, onto the shoreline of Sputnik Planum and then across its icy plains. They were made with the telescopic Long Range Reconnaissance Imager (LORRI) aboard New Horizons, over a timespan of about a minute centered on 11:36 UT on July 14 -- just about 15 minutes before New Horizons' closest approach to Pluto -- from a range of just 10,000 miles (17,000 kilometers). They were obtained with an unusual observing mode; instead of working in the usual "point and shoot," LORRI snapped pictures every three seconds while the Ralph/Multispectral Visual Imaging Camera (MVIC) aboard New Horizons was scanning the surface. This mode requires unusually short exposures to avoid blurring the images. http://photojournal.jpl.nasa.gov/catalog/PIA20201

Nearly extremal apparent horizons in simulations of merging black holes

NASA Astrophysics Data System (ADS)

Lovelace, Geoffrey; Scheel, Mark; Owen, Robert; Giesler, Matthew; Katebi, Reza; Szilagyi, Bela; Chu, Tony; Demos, Nicholas; Hemberger, Daniel; Kidder, Lawrence; Pfeiffer, Harald; Afshari, Nousha; SXS Collaboration

2015-04-01

The spin S of a Kerr black hole is bounded by the surface area A of its apparent horizon: 8 πS <= A . We present recent results (arXiv:1411.7297) for the extremality of apparent horizons for merging, rapidly rotating black holes with equal masses and equal spins aligned with the orbital angular momentum. Measuring the area and (using approximate Killing vectors) the spin on the individual and common apparent horizons, we find that the inequality 8 πS < A is satisfied but is very close to equality on the common apparent horizon at the instant it first appears--even for initial spins as large as S /M2 = 0 . 994 . We compute the smallest value e0 that Booth and Fairhurst's extremality parameter can take for any scaling of the horizon's null normal vectors, concluding that the common horizons are at least moderately close to extremal just after they appear. We construct binary-black-hole initial data with marginally trapped surfaces with 8 πS > A and e0 > 1 , but these surfaces are always surrounded by apparent horizons with 8 πS < A and e0 < 1 .

Wider horizons, wiser choices: horizon scanning for public health protection and improvement.

PubMed

Urquhart, Graham J; Saunders, Patrick

2017-06-01

Systematic continuous thinking about the future helps organizations, professions and communities to both prepare for, and shape, the future. This becomes ever more critical given the accelerating rate at which new data emerge, and in some cases uncertainties around their reliability and interpretation. Businesses with the capability to filter and analyse vast volumes of data to create knowledge and insights requiring action have a competitive advantage. Similarly Government and the public sector, including public health can be more effective and efficient through the early identification of emerging issues (both threats and opportunities). Horizon scanning approaches, and the use of resulting intelligence related to health protection and improvement were reviewed. Public health horizon scanning systems have to date focussed on health technologies and infectious diseases. While these have been successful there is a major gap in terms of non-infectious hazards and health improvement. Any system to meet this need must recognize the changed environment for delivering front line public health services and the critical role of local authorities and the local democratic process. This presents opportunities and challenges and this paper explores those dynamics describing an existing environment and health horizon scanning system which could readily and rapidly be re-engineered to provide a national service. © The Author 2016. Published by Oxford University Press on behalf of Faculty of Public Health. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Universality of P - V criticality in horizon thermodynamics

NASA Astrophysics Data System (ADS)

Hansen, Devin; Kubizňák, David; Mann, Robert B.

2017-01-01

We study P - V criticality of black holes in Lovelock gravities in the context of horizon thermodynamics. The corresponding first law of horizon thermodynamics emerges as one of the Einstein-Lovelock equations and assumes the universal (independent of matter content) form δ E = T δ S - P δ V , where P is identified with the total pressure of all matter in the spacetime (including a cosmological constant Λ if present). We compare this approach to recent advances in extended phase space thermodynamics of asymptotically AdS black holes where the `standard' first law of black hole thermodynamics is extended to include a pressure-volume term, where the pressure is entirely due to the (variable) cosmological constant. We show that both approaches are quite different in interpretation. Provided there is sufficient non-linearity in the gravitational sector, we find that horizon thermodynamics admits the same interesting black hole phase behaviour seen in the extended case, such as a Hawking-Page transition, Van der Waals like behaviour, and the presence of a triple point. We also formulate the Smarr formula in horizon thermodynamics and discuss the interpretation of the quantity E appearing in the horizon first law.

Gravitational Horizon(3)

NASA Astrophysics Data System (ADS)

Yang, Chao Yuan

2012-05-01

Anomalous decelerations of spacecraft Pioneer-10,11,etc could be interpreted as signal delay effect between speed of gravity and that of light as reflected in virtual scale, similar to covarying virtual scale effect in relative motion (http://arxiv.org/html/math-ph/0001019v5).A finite speed of gravity faster than light could be inferred (http://arXiv.org/html/physics/0001034v2). Measurements of gravitational variations by paraconical pendulum during a total solar eclipse infer the same(http://arXiv.org/html/physics/0001034v9). A finite Superluminal speed of gravity is the necessary condition to imply that there exists gravitational horizon (GH). Such "GH" of our Universe would stretch far beyond the cosmic event horizon of light. Dark energy may be owing to mutually interactive gravitational horizons of cousin universes. Sufficient condition for the conjecture is that the dark energy would be increasing with age of our Universe since accelerated expansion started about 5 Gyr ago, since more and more arrivals of "GH" of distant cousin universes would interact with "GH" of our Universe. The history of dark energy variations between then and now would be desirable(http://arXiv.org/html/physics/0001034). In "GH" conjecture, the neighborhood of cousin universes would be likely boundless in 4D-space-time without begining or end. The dark energy would keep all universes in continually accelerated expansion to eventual fragmentation. Fragments would crash and merge into bangs, big or small, to form another generation of cousin universes. These scenarios might offer a clue to what was before the big bang.

Horizon Quantum Mechanics: Spherically Symmetric and Rotating Sources

NASA Astrophysics Data System (ADS)

Casadio, Roberto; Giugno, Andrea; Giusti, Andrea; Micu, Octavian

2018-04-01

The Horizon Quantum Mechanics is an approach that allows one to analyse the gravitational radius of spherically symmetric systems and compute the probability that a given quantum state is a black hole. We first review the (global) formalism and show how it reproduces a gravitationally inspired GUP relation. This results leads to unacceptably large fluctuations in the horizon size of astrophysical black holes if one insists in describing them as (smeared) central singularities. On the other hand, if they are extended systems, like in the corpuscular models, no such issue arises and one can in fact extend the formalism to include asymptotic mass and angular momentum with the harmonic model of rotating corpuscular black holes. The Horizon Quantum Mechanics then shows that, in simple configurations, the appearance of the inner horizon is suppressed and extremal (macroscopic) geometries seem disfavoured.

Universal properties of the near-horizon optical geometry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gibbons, G. W.; Warnick, C. M.

2009-03-15

Making use of the fact that the optical geometry near a static nondegenerate Killing horizon is asymptotically hyperbolic, we investigate some universal features of black-hole horizons. Applying the Gauss-Bonnet theorem allows us to establish some general properties of gravitational lensing, valid for all black holes. Hyperbolic geometry allows us to find rates for the loss of scalar, vector, and fermionic ''hair'' as objects fall quasistatically towards the horizon, extending previous results for Schwarzschild to all static Killing horizons. In the process we find the Lienard-Wiechert potential for hyperbolic space and calculate the force between electrons mediated by neutrinos, extending themore » flat space result of Feinberg and Sucher. We further demonstrate how these techniques allow us to derive the exact Copson-Linet potential due to a point charge in a Schwarzschild background in a simple fashion.« less

SETAC launches global horizon scanning/research prioritization project

EPA Science Inventory

The SETAC World Council is pleased to announce the initiation of a Global Horizon Scanning and Prioritization Project aimed at identifying geographically specific research needs to address stressor impacts on environmental quality. In recent years, horizon scanning and research ...

Beyond usual care: the economic consequences of expanding treatment options in early pregnancy loss.

PubMed

Dalton, Vanessa K; Liang, Angela; Hutton, David W; Zochowski, Melissa K; Fendrick, A Mark

2015-02-01

The objective of this study was to estimate the economic consequences of expanding options for early pregnancy loss (EPL) treatment beyond expectant management and operating room surgical evacuation (usual care). We constructed a decision model using a hypothetical cohort of women undergoing EPL management within a 30 day horizon. Treatment options under the usual care arm include expectant management and surgical uterine evacuation in an operating room (OR). Treatment options under the expanded care arm included all evidence-based safe and effective treatment options for EPL: expectant management, misoprostol treatment, surgical uterine evacuation in an office setting, and surgical uterine evacuation in an OR. Probabilities of entering various treatment pathways were based on previously published observational studies. The cost per case was US $241.29 lower for women undergoing treatment in the expanded care model as compared with the usual care model (US $1033.29 per case vs US $1274.58 per case, expanded care and usual care, respectively). The model was the most sensitive to the failure rate of the expectant management arm, the cost of the OR surgical procedure, the proportion of women undergoing an OR surgical procedure under usual care, and the additional cost per patient associated with implementing and using the expanded care model. This study demonstrates that expanding women's treatment options for EPL beyond what is typically available can result in lower direct medical expenditures. Copyright © 2015 Elsevier Inc. All rights reserved.

From Orbit, Looking toward Mercury's Horizon

NASA Image and Video Library

2017-12-08

NASA image acquired: March 29, 2011 MESSENGER acquired this image of Mercury's horizon as the spacecraft was moving northward along the first orbit during which MDIS was turned on. Bright rays from Hokusai can be seen running north to south in the image. MDIS frequently acquired images that contained Mercury's horizon during the mission's three Mercury flybys. (Visit these links to see examples of horizon images from Mercury flyby 1, Mercury flyby 2, and Mercury flyby 3.) However, now that MESSENGER is in orbit about Mercury, views of Mercury's horizon in the images will be much less common. The field of view for MDIS will generally be filled with Mercury's surface as the instrument maps out the planet's geology in high resolution, stereo, and color. Occasionally, in order to obtain images of a certain portion of Mercury's surface, the horizon will also be visible. On March 17, 2011 (March 18, 2011, UTC), MESSENGER became the first spacecraft to orbit the planet Mercury. The mission is currently in its commissioning phase, during which spacecraft and instrument performance are verified through a series of specially designed checkout activities. In the course of the one-year primary mission, the spacecraft's seven scientific instruments and radio science investigation will unravel the history and evolution of the Solar System's innermost planet. Visit the Why Mercury? section of this website to learn more about the science questions that the MESSENGER mission has set out to answer. Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Join us on Facebook

Locating the Gribov horizon

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gao, Fei; Qin, Si-Xue; Roberts, Craig D.

We explore whether a tree-level expression for the gluon two-point function, supposed to express effects of an horizon term introduced to eliminate the Gribov ambiguity, is consistent with the propagator obtained in simulations of lattice-regularised quantum chromodynamics (QCD). In doing so, we insist that the gluon two-point function obey constraints that ensure a minimal level of consistency with parton-like behaviour at ultraviolet momenta. In consequence, we are led to a position which supports a conjecture that the gluon mass and horizon scale are equivalent emergent massscales, each with a value of roughly 0.5 GeV; and wherefrom it appears plausible thatmore » the dynamical generation of a running gluon mass may alone be sufficient to remove the Gribov ambiguity.« less

Locating the Gribov horizon

DOE PAGES

Gao, Fei; Qin, Si-Xue; Roberts, Craig D.; ...

2018-02-08

We explore whether a tree-level expression for the gluon two-point function, supposed to express effects of an horizon term introduced to eliminate the Gribov ambiguity, is consistent with the propagator obtained in simulations of lattice-regularised quantum chromodynamics (QCD). In doing so, we insist that the gluon two-point function obey constraints that ensure a minimal level of consistency with parton-like behaviour at ultraviolet momenta. In consequence, we are led to a position which supports a conjecture that the gluon mass and horizon scale are equivalent emergent massscales, each with a value of roughly 0.5 GeV; and wherefrom it appears plausible thatmore » the dynamical generation of a running gluon mass may alone be sufficient to remove the Gribov ambiguity.« less

NASA's New Horizons Pluto Mission: Continuing Voyager's Legacy o

NASA Image and Video Library

2014-08-25

Dr. Alan Stern, Principal Investigator on NASA's New Horizons Mission, left, delivers closing remarks following a panel discussion at the "NASA's New Horizons Pluto Mission: Continuing Voyager's Legacy of Exploration" event on Monday, August, 25, 2014, in the James E. Webb Auditorium at NASA Headquarters in Washington, DC. The panelists gave their accounts of Voyager's encounter with Neptune and discussed their current assignments on NASA's New Horizons mission to Pluto. Photo Credit: (NASA/Joel Kowsky)

NASA's New Horizons Pluto Mission: Continuing Voyager's Legacy o

NASA Image and Video Library

2014-08-25

Dr. Alan Stern, Principal Investigator on NASA's New Horizons Mission, delivers closing remarks following a panel discussion at the "NASA's New Horizons Pluto Mission: Continuing Voyager's Legacy of Exploration" event on Monday, August, 25, 2014, in the James E. Webb Auditorium at NASA Headquarters in Washington, DC. The panelists gave their accounts of Voyager's encounter with Neptune and discussed their current assignments on NASA's New Horizons mission to Pluto. Photo Credit: (NASA/Joel Kowsky)

Universal properties from a local geometric structure of a Killing horizon

NASA Astrophysics Data System (ADS)

Koga, Jun-ichirou

2007-06-01

We consider universal properties that arise from a local geometric structure of a Killing horizon, and analyse whether such universal properties give rise to degeneracy of classical configurations. We first introduce a non-perturbative definition of such a local geometric structure, which we call an asymptotic Killing horizon. It is then shown that infinitely many asymptotic Killing horizons reside on a common null hypersurface, once there exists one asymptotic Killing horizon, which is thus considered as degeneracy. In order to see how this degeneracy is physically meaningful, we analyse also the acceleration of the orbits of the vector that generates an asymptotic Killing horizon. It is shown that there exists the diff(S1) or diff(R1) sub-algebra on an asymptotic Killing horizon universally, which is picked out naturally, based on the behaviour of the acceleration. We argue that the discrepancy between string theory and the Euclidean approach in the entropy of an extreme black hole may be resolved, if the microscopic states responsible for black hole thermodynamics are connected with asymptotic Killing horizons.

Planning horizon affects prophylactic decision-making and epidemic dynamics

DOE PAGES

Nardin, Luis G.; Miller, Craig R.; Ridenhour, Benjamin J.; ...

2016-11-08

The spread of infectious diseases can be impacted by human behavior, and behavioral decisions often depend implicitly on a planning horizon?the time in the future over which options are weighed. We investigate the effects of planning horizons on epidemic dynamics. We developed an epidemiological agent-based model (along with an ODE analog) to explore the decision-making of self-interested individuals on adopting prophylactic behavior. The decision-making process incorporates prophylaxis efficacy and disease prevalence with the individuals? payoffs and planning horizon. Our results show that for short and long planning horizons individuals do not consider engaging in prophylactic behavior. In contrast, individuals adoptmore » prophylactic behavior when considering intermediate planning horizons. Such adoption, however, is not always monotonically associated with the prevalence of the disease, depending on the perceived protection efficacy and the disease parameters. Adoption of prophylactic behavior reduces the epidemic peak size while prolonging the epidemic and potentially generates secondary waves of infection. Lastly, these effects can be made stronger by increasing the behavioral decision frequency or distorting an individual's perceived risk of infection.« less

Planning horizon affects prophylactic decision-making and epidemic dynamics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nardin, Luis G.; Miller, Craig R.; Ridenhour, Benjamin J.

The spread of infectious diseases can be impacted by human behavior, and behavioral decisions often depend implicitly on a planning horizon?the time in the future over which options are weighed. We investigate the effects of planning horizons on epidemic dynamics. We developed an epidemiological agent-based model (along with an ODE analog) to explore the decision-making of self-interested individuals on adopting prophylactic behavior. The decision-making process incorporates prophylaxis efficacy and disease prevalence with the individuals? payoffs and planning horizon. Our results show that for short and long planning horizons individuals do not consider engaging in prophylactic behavior. In contrast, individuals adoptmore » prophylactic behavior when considering intermediate planning horizons. Such adoption, however, is not always monotonically associated with the prevalence of the disease, depending on the perceived protection efficacy and the disease parameters. Adoption of prophylactic behavior reduces the epidemic peak size while prolonging the epidemic and potentially generates secondary waves of infection. Lastly, these effects can be made stronger by increasing the behavioral decision frequency or distorting an individual's perceived risk of infection.« less

Planning horizon affects prophylactic decision-making and epidemic dynamics.

PubMed

Nardin, Luis G; Miller, Craig R; Ridenhour, Benjamin J; Krone, Stephen M; Joyce, Paul; Baumgaertner, Bert O

2016-01-01

The spread of infectious diseases can be impacted by human behavior, and behavioral decisions often depend implicitly on a planning horizon-the time in the future over which options are weighed. We investigate the effects of planning horizons on epidemic dynamics. We developed an epidemiological agent-based model (along with an ODE analog) to explore the decision-making of self-interested individuals on adopting prophylactic behavior. The decision-making process incorporates prophylaxis efficacy and disease prevalence with the individuals' payoffs and planning horizon. Our results show that for short and long planning horizons individuals do not consider engaging in prophylactic behavior. In contrast, individuals adopt prophylactic behavior when considering intermediate planning horizons. Such adoption, however, is not always monotonically associated with the prevalence of the disease, depending on the perceived protection efficacy and the disease parameters. Adoption of prophylactic behavior reduces the epidemic peak size while prolonging the epidemic and potentially generates secondary waves of infection. These effects can be made stronger by increasing the behavioral decision frequency or distorting an individual's perceived risk of infection.

Entropy bound of horizons for accelerating, rotating and charged Plebanski–Demianski black hole

DOE Office of Scientific and Technical Information (OSTI.GOV)

Debnath, Ujjal, E-mail: ujjaldebnath@yahoo.com

We first review the accelerating, rotating and charged Plebanski–Demianski (PD) black hole, which includes the Kerr–Newman rotating black hole and the Taub-NUT spacetime. The main feature of this black hole is that it has 4 horizons like event horizon, Cauchy horizon and two accelerating horizons. In the non-extremal case, the surface area, entropy, surface gravity, temperature, angular velocity, Komar energy and irreducible mass on the event horizon and Cauchy horizon are presented for PD black hole. The entropy product, temperature product, Komar energy product and irreducible mass product have been found for event horizon and Cauchy horizon. Also their sumsmore » are found for both horizons. All these relations are dependent on the mass of the PD black hole and other parameters. So all the products are not universal for PD black hole. The entropy and area bounds for two horizons have been investigated. Also we found the Christodoulou–Ruffini mass for extremal PD black hole. Finally, using first law of thermodynamics, we also found the Smarr relation for PD black hole.« less

New Horizons Event: The First Mission to the Pluto System

NASA Image and Video Library

2014-08-25

Dr. Alan Stern, New Horizons principal investigator, speaks on a panel at the "New Horizons: The First Mission to the Pluto System and the Kuiper Belt" Event at NASA Headquarters in Washington, DC Monday, August 25, 2014. Scientists discussed how the first images of Pluto and its moons would be captured by the New Horizons spacecraft during a five month long reconnaissance flyby study starting in the summer of 2015. New Horizons launched on January 19, 2006 and is scheduled to make its closest approach to Pluto on July 14, 2015. Photo Credit: (NASA/Aubrey Gemignani)

Event and Apparent Horizon Finders for 3 + 1 Numerical Relativity.

PubMed

Thornburg, Jonathan

2007-01-01

Event and apparent horizons are key diagnostics for the presence and properties of black holes. In this article I review numerical algorithms and codes for finding event and apparent horizons in numerically-computed spacetimes, focusing on calculations done using the 3 + 1 ADM formalism. The event horizon of an asymptotically-flat spacetime is the boundary between those events from which a future-pointing null geodesic can reach future null infinity and those events from which no such geodesic exists. The event horizon is a (continuous) null surface in spacetime. The event horizon is defined nonlocally in time : it is a global property of the entire spacetime and must be found in a separate post-processing phase after all (or at least the nonstationary part) of spacetime has been numerically computed. There are three basic algorithms for finding event horizons, based on integrating null geodesics forwards in time, integrating null geodesics backwards in time, and integrating null surfaces backwards in time. The last of these is generally the most efficient and accurate. In contrast to an event horizon, an apparent horizon is defined locally in time in a spacelike slice and depends only on data in that slice, so it can be (and usually is) found during the numerical computation of a spacetime. A marginally outer trapped surface (MOTS) in a slice is a smooth closed 2-surface whose future-pointing outgoing null geodesics have zero expansion Θ. An apparent horizon is then defined as a MOTS not contained in any other MOTS. The MOTS condition is a nonlinear elliptic partial differential equation (PDE) for the surface shape, containing the ADM 3-metric, its spatial derivatives, and the extrinsic curvature as coefficients. Most "apparent horizon" finders actually find MOTSs. There are a large number of apparent horizon finding algorithms, with differing trade-offs between speed, robustness, accuracy, and ease of programming. In axisymmetry, shooting algorithms work well

The Horizon Report: 2010 Australia-New Zealand Edition

ERIC Educational Resources Information Center

Johnson, L.; Smith, R.; Levine, A.; Haywood, K.

2010-01-01

The internationally recognized series of "Horizon Reports" is part of the New Media Consortium's Horizon Project, a comprehensive research venture established in 2002 that identifies and describes emerging technologies likely to have a large impact over the coming five years on a variety of sectors around the globe. This volume, the…

The NMC Horizon Report: 2013 K-12 Edition

ERIC Educational Resources Information Center

Johnson, L.; Adams Becker, S.; Cummins, M.; Estrada V.; Freeman, A.; Ludgate, H.

2013-01-01

"The NMC Horizon Report" series is the most visible outcome of the New Media Consortium (NMC) Horizon Project, an ongoing research effort established in 2002 that identifies and describes emerging technologies likely to have a large impact on teaching, learning, research, or creative expression within education around the globe. This…

The NMC Horizon Report: 2015 Higher Education Edition

ERIC Educational Resources Information Center

Johnson, L.; Adams Becker, S.; Estrada, V.; Freeman, A.

2015-01-01

The "NMC Horizon Report: 2015 Higher Education Edition" is a collaborative effort between the New Media Consortium (NMC) and the EDUCAUSE Learning Initiative (ELI). This 12th edition describes annual findings from the NMC Horizon Project, an ongoing research project designed to identify and describe emerging technologies likely to have…

"Far Horizons" -- Near-space Exploration At The Adler Planetarium

NASA Astrophysics Data System (ADS)

Hammergren, Mark; Gyuk, G.; Friedman, R. B.

2011-01-01

Over the past four years, the Adler Planetarium has developed a diverse suite of educational activities involving hands-on scientific exploration via our "Far Horizons" high-altitude ballooning program. These efforts largely have been focused on increasing excitement and motivation for learning outside of school time, and include middle school summer camps, a high school summer program (the Astro-Science Workshop), school-year internships for high school students, summer internships for undergraduates, a NSF-funded graduate fellowship, and an active public volunteer program. In 2010, our programs were dedicated to the memory of renowned Chicago adventurer and explorer Steve Fossett. In 2011, in continued tribute to Steve Fossett, we further expand our out-of-school time programs with a summer workshop designed to enable high school teachers to form and advise student high-altitude ballooning clubs. This model program will be developed as one element of our ongoing partnership with the Air Force Academy High School in Chicago. This material is based in part upon work supported by the National Science Foundation under Grant No. 0525995.

Forecasting space weather over short horizons: Revised and updated estimates

NASA Astrophysics Data System (ADS)

Reikard, Gordon

2018-07-01

Space weather reflects multiple causes. There is a clear influence for the sun on the near-earth environment. Solar activity shows evidence of chaotic properties, implying that prediction may be limited beyond short horizons. At the same time, geomagnetic activity also reflects the rotation of the earth's core, and local currents in the ionosphere. The combination of influences means that geomagnetic indexes behave like multifractals, exhibiting nonlinear variability, with intermittent outliers. This study tests a range of models: regressions, neural networks, and a frequency domain algorithm. Forecasting tests are run for sunspots and irradiance from 1820 onward, for the Aa geomagnetic index from 1868 onward, and the Am index from 1959 onward, over horizons of 1-7 days. For irradiance and sunspots, persistence actually does better over short horizons. None of the other models really dominate. For the geomagnetic indexes, the persistence method does badly, while the neural net also shows large errors. The remaining models all achieve about the same level of accuracy. The errors are in the range of 48% at 1 day, and 54% at all later horizons. Additional tests are run over horizons of 1-4 weeks. At 1 week, the best models reduce the error to about 35%. Over horizons of four weeks, the model errors increase. The findings are somewhat pessimistic. Over short horizons, geomagnetic activity exhibits so much random variation that the forecast errors are extremely high. Over slightly longer horizons, there is some improvement from estimating in the frequency domain, but not a great deal. Including solar activity in the models does not yield any improvement in accuracy.

The Horizon Report: 2009 Australia-New Zealand Edition

ERIC Educational Resources Information Center

Johnson, L.; Levine, A.; Smith, R.; Smythe, T.; Stone, S.

2009-01-01

The New Media Consortium's Horizon Project is an ongoing research project that aims to identify and describe emerging technologies likely to have a large impact on teaching, learning, or creative inquiry within education around the globe over a five-year time period. The project's central products are the "Horizon Reports", an annual…

The NMC Horizon Report: 2011 K-12 Edition

ERIC Educational Resources Information Center

Johnson, L.; Adams, S.; Haywood, K.

2011-01-01

"The NMC Horizon Report" series is the most visible outcome of the New Media Consortium. (NMC) Horizon Project, an ongoing research effort established in 2002 that identifies and describes emerging technologies likely to have a large impact on teaching, learning, research, or creative expression within education around the globe. This volume, "The…

The NMC Horizon Report: 2014 K-12 Edition

ERIC Educational Resources Information Center

Johnson, L.; Adams Becker, S.; Estrada, V.; Freeman, A.

2014-01-01

"The NMC Horizon Report" series is the most visible outcome of the New Media Consortium (NMC) Horizon Project, an ongoing research effort established in 2002 that identifies and describes emerging technologies likely to have a large impact on teaching, learning, research, or creative expression within every sector of education in some 65…

The NMC Horizon Report: 2012 Higher Education Edition

ERIC Educational Resources Information Center

Johnson, L.; Adams, S.; Cummins, M.

2012-01-01

The internationally recognized "NMC Horizon Report" series and regional "NMC Technology Outlooks" are part of the NMC Horizon Project, a comprehensive research venture established in 2002 that identifies and describes emerging technologies likely to have a large impact over the coming five years in education around the globe. This volume, the "NMC…

Does the black hole shadow probe the event horizon geometry?

NASA Astrophysics Data System (ADS)

Cunha, Pedro V. P.; Herdeiro, Carlos A. R.; Rodriguez, Maria J.

2018-04-01

There is an exciting prospect of obtaining the shadow of astrophysical black holes (BHs) in the near future with the Event Horizon Telescope. As a matter of principle, this justifies asking how much one can learn about the BH horizon itself from such a measurement. Since the shadow is determined by a set of special photon orbits, rather than horizon properties, it is possible that different horizon geometries yield similar shadows. One may then ask how sensitive is the shadow to details of the horizon geometry? As a case study, we consider the double Schwarzschild BH and analyze the impact on the lensing and shadows of the conical singularity that holds the two BHs in equilibrium—herein taken to be a strut along the symmetry axis in between the two BHs. Whereas the conical singularity induces a discontinuity of the scattering angle of photons, clearly visible in the lensing patterns along the direction of the strut's location, it produces no observable effect on the shadows, whose edges remain everywhere smooth. The latter feature is illustrated by examples including both equal and unequal mass BHs. This smoothness contrasts with the intrinsic geometry of the (spatial sections of the) horizon of these BHs, which is not smooth, and provides a sharp example on how BH shadows are insensitive to some horizon geometry details. This observation, moreover, suggests that for the study of their shadows, this static double BH system may be an informative proxy for a dynamical binary.

Pluto's Solar Occultation from New Horizons

NASA Astrophysics Data System (ADS)

Young, Leslie; Kammer, Joshua; Steffl, Andrew J.; Gladstone, Randy; Summers, Michael; Strobel, Darrell F.; Hinson, David P.; Stern, S. Alan; Weaver, Harold A.; Olkin, Catherine; Ennico, Kimberly; McComas, Dave; New Horizons Atmospheres Science Theme Team

2017-10-01

The Alice instrument on NASA’s New Horizons spacecraft observed an ultraviolet solar occultation by Pluto's atmosphere on 2015 July 14. We derived line-of-sight abundances and local number densities for the major species (N2 and CH4) and minor hydrocarbons (C2H2, C2H4, C2H6), and line-of-sight optical depth and extinction coefficients for the haze. Our major conclusions are that (1) we confirmed temperatures in Pluto’s upper atmosphere that were colder than expected before the New Horizons flyby, with upper atmospheric temperatures near 65-68 K, and subsequently lower escape rates, (2) the lower atmosphere was very stable, placing the homopause within 12 km of the surface, (3) the abundance profiles of the “C2Hx hydrocarbons” had non-exponential density profiles that compare favorably with models for hydrocarbon production near 300-400 km and haze condensation near 200 km, and (4) haze had an extinction coefficient approximately proportional to N2 density.This work was supported by NASA’s New Horizons project.

Fractal markets: Liquidity and investors on different time horizons

NASA Astrophysics Data System (ADS)

Li, Da-Ye; Nishimura, Yusaku; Men, Ming

2014-08-01

In this paper, we propose a new agent-based model to study the source of liquidity and the “emergent” phenomenon in financial market with fractal structure. The model rests on fractal market hypothesis and agents with different time horizons of investments. What is interesting is that though the agent-based model reveals that the interaction between these heterogeneous agents affects the stability and liquidity of the financial market the real world market lacks detailed data to bring it to light since it is difficult to identify and distinguish the investors with different time horizons in the empirical approach. results show that in a relatively short period of time fractal market provides liquidity from investors with different horizons and the market gains stability when the market structure changes from uniformity to diversification. In the real world the fractal structure with the finite of horizons can only stabilize the market within limits. With the finite maximum horizons, the greater diversity of the investors and the fractal structure will not necessarily bring more stability to the market which might come with greater fluctuation in large time scale.

Radiation from quantum weakly dynamical horizons in loop quantum gravity.

PubMed

Pranzetti, Daniele

2012-07-06

We provide a statistical mechanical analysis of quantum horizons near equilibrium in the grand canonical ensemble. By matching the description of the nonequilibrium phase in terms of weakly dynamical horizons with a local statistical framework, we implement loop quantum gravity dynamics near the boundary. The resulting radiation process provides a quantum gravity description of the horizon evaporation. For large black holes, the spectrum we derive presents a discrete structure which could be potentially observable.

MAP Attitude Control System Design and Flight Performance

NASA Technical Reports Server (NTRS)

Andrews, S. F.; ODonnell, J. R.; Bauer, Frank H. (Technical Monitor)

2002-01-01

The Microwave Anisotropy Probe (MAP) is a follow-on to the Differential Microwave Radiometer (DMR) instrument on the Cosmic Background Explorer (COBE) spacecraft. To make a full-sky map of cosmic microwave background fluctuations, a combination fast spin and slow precession motion will be used that will cover the entire celestial sphere in six months. The spin rate should be an order of magnitude higher than the precession rate, and each rate should be tightly controlled. The sunline angle should be 22.5 +/- 0.25 deg. Sufficient attitude knowledge must be provided to yield instrument pointing to a standard deviation of 1.3 arc-minutes RSS three axes. In addition, the spacecraft must be able to acquire and hold the sunline at initial acquisition, and in the event of a failure. Finally. the spacecraft must be able to slew to the proper burn orientations and to the proper off-sunline attitude to start the compound spin. The design and flight performance of the Attitude Control System on MAP that meets these requirements will be discussed.

Near-horizon conformal symmetry and black hole entropy.

PubMed

Carlip, S

2002-06-17

Near an event horizon, the action of general relativity acquires a new asymptotic conformal symmetry. For two-dimensional dilaton gravity, this symmetry results in a chiral Virasoro algebra, and Cardy's formula for the density of states reproduces the Bekenstein-Hawking entropy. This lends support to the notion that black hole entropy is controlled universally by conformal symmetry near the horizon.

Parametric Covariance Model for Horizon-Based Optical Navigation

NASA Technical Reports Server (NTRS)

Hikes, Jacob; Liounis, Andrew J.; Christian, John A.

2016-01-01

This Note presents an entirely parametric version of the covariance for horizon-based optical navigation measurements. The covariance can be written as a function of only the spacecraft position, two sensor design parameters, the illumination direction, the size of the observed planet, the size of the lit arc to be used, and the total number of observed horizon points. As a result, one may now more clearly understand the sensitivity of horizon-based optical navigation performance as a function of these key design parameters, which is insight that was obscured in previous (and nonparametric) versions of the covariance. Finally, the new parametric covariance is shown to agree with both the nonparametric analytic covariance and results from a Monte Carlo analysis.

DNAism: exploring genomic datasets on the web with Horizon Charts.

PubMed

Rio Deiros, David; Gibbs, Richard A; Rogers, Jeffrey

2016-01-27

Computational biologists daily face the need to explore massive amounts of genomic data. New visualization techniques can help researchers navigate and understand these big data. Horizon Charts are a relatively new visualization method that, under the right circumstances, maximizes data density without losing graphical perception. Horizon Charts have been successfully applied to understand multi-metric time series data. We have adapted an existing JavaScript library (Cubism) that implements Horizon Charts for the time series domain so that it works effectively with genomic datasets. We call this new library DNAism. Horizon Charts can be an effective visual tool to explore complex and large genomic datasets. Researchers can use our library to leverage these techniques to extract additional insights from their own datasets.

Genesis of petroduric and petrocalcic horizons in Latinamerica volcanic soils

NASA Astrophysics Data System (ADS)

Quantin, Paul

2010-05-01

Introduction. In Latinamerica, from Mexico to Chile, there are indurated volcanic soils horizons, named 'tepetate' in Mexico or cangahua in the Andes Mountains. Apart from original volcanic tuffs, these horizons were produced by pedogenesis: either through a former weathering of volcanic ash layers into fragic and later to petrocalcic horizons; or after a former soil formation through a second process of transformation from clayey volcanic soils to silicified petroduric horizons. This oral presentation will briefly deal with the formation of petroduric horizons in Mexico and petrocalcic horizon in Ecuador. Petroduric horizon genesis in Mexico. A soil climato-toposequence, near to Veracruz (Rossignol & Quantin, 1997), shows downwards an evolution from a ferralic Nitisol to a petroduric Durisol. A Durisol profile comports these successive horizons: at the top A and Eg, then columnar Btg-sim, laminar Bt-sim , prismatic Bsim, plinthite Cg, over andesite lava flow. Among its main features are especially recorded: clay mineralogy, microscopy and HRTEM. These data show: an increase in cristobalite at the expenses of 0.7 nm halloysite in Egsiltans, laminar Bt-sim, around or inside the columns or prisms of Btg-sim and Bsimhorizons. HRTEM (Elsass & al 2000) on ultra thin sections reveals an 'epigenesis' of clay sheets by amorphous silica, to form successively A-opal, Ct-opal and microcrystalline cristobalite. From these data and some groundwater chemical analyses, a scenario of duripan formation from a past clayey Nitisol is inferred: clay eluviation-illuviation process? alternate redoximorphy? clay degradation, Al leaching and Si accumulation, to form successively A-opal, Ct-opal and cristobalite. Petrocalcic horizon genesis in Ecuador. A soil climato-toposequence on pyroclastic flows, near to Bolivar in Ecuador (Quantin & Zebrowski, 1997), shows downwards the evolution from fragic-eutric-vitric Cambisols to petrocalcic-vitric Phaeozems, at the piedmont under semi

Accurate, reliable prototype earth horizon sensor head

NASA Technical Reports Server (NTRS)

Schwarz, F.; Cohen, H.

1973-01-01

The design and performance is described of an accurate and reliable prototype earth sensor head (ARPESH). The ARPESH employs a detection logic 'locator' concept and horizon sensor mechanization which should lead to high accuracy horizon sensing that is minimally degraded by spatial or temporal variations in sensing attitude from a satellite in orbit around the earth at altitudes in the 500 km environ 1,2. An accuracy of horizon location to within 0.7 km has been predicted, independent of meteorological conditions. This corresponds to an error of 0.015 deg-at 500 km altitude. Laboratory evaluation of the sensor indicates that this accuracy is achieved. First, the basic operating principles of ARPESH are described; next, detailed design and construction data is presented and then performance of the sensor under laboratory conditions in which the sensor is installed in a simulator that permits it to scan over a blackbody source against background representing the earth space interface for various equivalent plant temperatures.

Black hole and cosmos with multiple horizons and multiple singularities in vector-tensor theories

NASA Astrophysics Data System (ADS)

Gao, Changjun; Lu, Youjun; Yu, Shuang; Shen, You-Gen

2018-05-01

A stationary and spherically symmetric black hole (e.g., Reissner-Nordström black hole or Kerr-Newman black hole) has, at most, one singularity and two horizons. One horizon is the outer event horizon and the other is the inner Cauchy horizon. Can we construct static and spherically symmetric black hole solutions with N horizons and M singularities? The de Sitter cosmos has only one apparent horizon. Can we construct cosmos solutions with N horizons? In this article, we present the static and spherically symmetric black hole and cosmos solutions with N horizons and M singularities in the vector-tensor theories. Following these motivations, we also construct the black hole solutions with a firewall. The deviation of these black hole solutions from the usual ones can be potentially tested by future measurements of gravitational waves or the black hole continuum spectrum.

Eocene volcanism and the origin of horizon A

USGS Publications Warehouse

Gibson, T.G.; Towe, K.M.

1971-01-01

A series of closely time-equivalent deposits that correlate with seismic reflector horizon A exists along the coast of eastern North America. These sediments of Late-Early to Early-Middle Eocene age contain an authigenic mineral suite indicative of the alteration of volcanic glass. A volcanic origin for these siliceous deposits onshore is consistent with a volcanic origin for the cherts of horizon A offshore.

Nearly extremal apparent horizons in simulations of merging black holes

NASA Astrophysics Data System (ADS)

Lovelace, Geoffrey; Scheel, Mark A.; Owen, Robert; Giesler, Matthew; Katebi, Reza; Szilágyi, Béla; Chu, Tony; Demos, Nicholas; Hemberger, Daniel A.; Kidder, Lawrence E.; Pfeiffer, Harald P.; Afshari, Nousha

2015-03-01

The spin angular momentum S of an isolated Kerr black hole is bounded by the surface area A of its apparent horizon: 8π S≤slant A, with equality for extremal black holes. In this paper, we explore the extremality of individual and common apparent horizons for merging, rapidly spinning binary black holes. We consider simulations of merging black holes with equal masses M and initial spin angular momenta aligned with the orbital angular momentum, including new simulations with spin magnitudes up to S/{{M}2}=0.994. We measure the area and (using approximate Killing vectors) the spin on the individual and common apparent horizons, finding that the inequality 8π S\\lt A is satisfied in all cases but is very close to equality on the common apparent horizon at the instant it first appears. We also evaluate the Booth-Fairhurst extremality, whose value for a given apparent horizon depends on the scaling of the horizon’s null normal vectors. In particular, we introduce a gauge-invariant lower bound on the extremality by computing the smallest value that Booth and Fairhurst’s extremality parameter can take for any scaling. Using this lower bound, we conclude that the common horizons are at least moderately close to extremal just after they appear. Finally, following Lovelace et al (2008 Phys. Rev. D 78 084017), we construct quasiequilibrium binary-black hole initial data with ‘overspun’ marginally trapped surfaces with 8π S\\gt A. We show that the overspun surfaces are indeed superextremal: our lower bound on their Booth-Fairhurst extremality exceeds unity. However, we confirm that these superextremal surfaces are always surrounded by marginally outer trapped surfaces (i.e., by apparent horizons) with 8π S\\lt A. The extremality lower bound on the enclosing apparent horizon is always less than unity but can exceed the value for an extremal Kerr black hole.

Noncommutative FRW Apparent Horizon and Hawking Radiation

NASA Astrophysics Data System (ADS)

Bouhallouf, H.; Mebarki, N.; Aissaoui, H.

2017-11-01

In the context of noncommutative (NCG) gauge gravity, and using a cosmic time power law formula for the scale factor, a Friedman-Robertson-Walker (FRW) like metric is obtained. Within the fermions tunneling effect approach and depending on the various intervals of the power parameter, expressions of the apparent horizon are also derived. It is shown that in some regions of the parameter space, a pure NCG trapped horizon does exist leading to new interpretation of the role played by the noncommutativity of the space-time.

Robust Consumption-Investment Problem on Infinite Horizon

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zawisza, Dariusz, E-mail: dariusz.zawisza@im.uj.edu.pl

In our paper we consider an infinite horizon consumption-investment problem under a model misspecification in a general stochastic factor model. We formulate the problem as a stochastic game and finally characterize the saddle point and the value function of that game using an ODE of semilinear type, for which we provide a proof of an existence and uniqueness theorem for its solution. Such equation is interested on its own right, since it generalizes many other equations arising in various infinite horizon optimization problems.

Generic weak isolated horizons

NASA Astrophysics Data System (ADS)

Chatterjee, Ayan; Ghosh, Amit

2006-12-01

Weak isolated horizon boundary conditions have been relaxed supposedly to their weakest form so that both zeroth and first laws of black hole mechanics hold. This makes the formulation more amenable for applications in both analytic and numerical relativities. It also unifies the phase spaces of non-extremal and extremal black holes.

Sonic horizon formation for oscillating Bose-Einstein condensates in isotropic harmonic potential

PubMed Central

Wang, Ying; Zhou, Yu; Zhou, Shuyu

2016-01-01

We study the sonic horizon phenomena of the oscillating Bose-Einstein condensates in isotropic harmonic potential. Based on the Gross-Pitaevskii equation model and variational method, we derive the original analytical formula for the criteria and lifetime of the formation of the sonic horizon, demonstrating pictorially the interaction parameter dependence for the occur- rence of the sonic horizon and damping effect of the system distribution width. Our analytical results corroborate quantitatively the particular features of the sonic horizon reported in previous numerical study. PMID:27922129

Supertranslations and Superrotations at the Black Hole Horizon.

PubMed

Donnay, Laura; Giribet, Gaston; González, Hernán A; Pino, Miguel

2016-03-04

We show that the asymptotic symmetries close to nonextremal black hole horizons are generated by an extension of supertranslations. This group is generated by a semidirect sum of Virasoro and Abelian currents. The charges associated with the asymptotic Killing symmetries satisfy the same algebra. When considering the special case of a stationary black hole, the zero mode charges correspond to the angular momentum and the entropy at the horizon.

New Horizons Tracks an Asteroid

NASA Image and Video Library

2007-04-02

The two pots in this image are a composite of two images of asteroid 2002 JF56 taken on June 11 and June 12, 2006, with the Multispectral Visible Imaging Camera component of the New Horizons Ralph imager.

Aerosol physical properties from satellite horizon inversion

NASA Technical Reports Server (NTRS)

Gray, C. R.; Malchow, H. L.; Merritt, D. C.; Var, R. E.; Whitney, C. K.

1973-01-01

The feasibility is investigated of determining the physical properties of aerosols globally in the altitude region of 10 to 100 km from a satellite horizon scanning experiment. The investigation utilizes a horizon inversion technique previously developed and extended. Aerosol physical properties such as number density, size distribution, and the real and imaginary components of the index of refraction are demonstrated to be invertible in the aerosol size ranges (0.01-0.1 microns), (0.1-1.0 microns), (1.0-10 microns). Extensions of previously developed radiative transfer models and recursive inversion algorithms are displayed.

Maximal volume behind horizons without curvature singularity

NASA Astrophysics Data System (ADS)

Wang, Shao-Jun; Guo, Xin-Xuan; Wang, Towe

2018-01-01

The black hole information paradox is related to the area of event horizon, and potentially to the volume and singularity behind it. One example is the complexity/volume duality conjectured by Stanford and Susskind. Accepting the proposal of Christodoulou and Rovelli, we calculate the maximal volume inside regular black holes, which are free of curvature singularity, in asymptotically flat and anti-de Sitter spacetimes respectively. The complexity/volume duality is then applied to anti-de Sitter regular black holes. We also present an analytical expression for the maximal volume outside the de Sitter horizon.

New Horizons Pluto Flyby Guest Operations

NASA Astrophysics Data System (ADS)

Simon, M.; Turney, D.; Fisher, S.; Carr, S. S.

2015-12-01

On July 14, 2015, after 9.5 years of cruise, NASA's New Horizons spacecraft flew past the Pluto system to gather first images humankind had ever seen on Pluto and its five moons. While much has been discovered about the Pluto system since New Horizons launch in 2006, the system has never been imaged at high resolution and anticipation of the "First Light" of the Pluto system had been anticipated by planetary enthusiasts for decades. The Johns Hopkins Applied Physics Laboratory (APL), which built and operates New Horizons, was the focal point for gathering three distinct groups: science and engineering team members; media and public affairs representatives; and invited public, including VIP's. Guest operations activities were focused on providing information primarily to the invited public and VIP's. High level objectives for the Guest Operations team was set to entertain and inform the general public, offer media reaction shots, and to deconflict activities for the guests from media activities wherever possible. Over 2000 people arrived at APL in the days surrounding closest approach for guest, science or media operations tracks. Reaction and coverage of the Guest Operations events was universally positive and global in impact: iconic pictures of the auditorium waving flags during the moment of closest approach were published in media outlets on every continent. Media relations activities ensured coverage in all key media publications targeted for release, such as the New York Times, Science, Le Monde, and Nature. Social and traditional media coverage of the events spanned the globe. Guest operations activities are designed to ensure that a guest has a memorable experience and leaves with a lifelong memory of the mission and their partnership in the activity. Results, lessons learned, and other data from the New Horizons guest operations activity will be presented and analyzed.

New Horizons Event: The First Mission to the Pluto System

NASA Image and Video Library

2014-08-25

Dr. Ed Stone, Voyager project scientist, speaks on a panel at the "New Horizons: The First Mission to the Pluto System and the Kuiper Belt" Event at NASA Headquarters in Washington, DC Monday, August 25, 2014. Scientists discussed how the first images of Pluto and its moons would be captured by the New Horizons spacecraft during a five month long reconnaissance flyby study starting in the summer of 2015. New Horizons launched on January 19, 2006 and is scheduled to make its closest approach to Pluto on July 14, 2015. Photo Credit: (NASA/Aubrey Gemignani)

New Horizons Event: The First Mission to the Pluto System

NASA Image and Video Library

2014-08-25

An audience member asks the panelists a question at the "New Horizons: The First Mission to the Pluto System and the Kuiper Belt" Event at NASA Headquarters in Washington, DC Monday, August 25, 2014. Scientists discussed how the first images of Pluto and its moons would be captured by the New Horizons spacecraft during a five month long reconnaissance flyby study starting in the summer of 2015. New Horizons launched on January 19, 2006 and is scheduled to make its closest approach to Pluto on July 14, 2015. Photo Credit: (NASA/Aubrey Gemignani)

Hair-brane ideas on the horizon

DOE PAGES

Martinec, Emil J.; Niehoff, Ben E.

2015-11-27

We continue an examination of the microstate geometries program begun in arXiv:1409.6017, focussing on the role of branes that wrap the cycles which degenerate when a throat in the geometry deepens and a horizon forms. An associated quiver quantum mechanical model of minimally wrapped branes exhibits a non-negligible fraction of the gravitational entropy, which scales correctly as a function of the charges. The results suggest a picture of AdS3/CFT2 duality wherein the long string that accounts for BTZ black hole entropy in the CFT description, can also be seen to inhabit the horizon of BPS black holes on the gravitymore » side.« less

Horizon quantum fuzziness for non-singular black holes

NASA Astrophysics Data System (ADS)

Giugno, Andrea; Giusti, Andrea; Helou, Alexis

2018-03-01

We study the extent of quantum gravitational effects in the internal region of non-singular, Hayward-like solutions of Einstein's field equations according to the formalism known as horizon quantum mechanics. We grant a microscopic description to the horizon by considering a huge number of soft, off-shell gravitons, which superimpose in the same quantum state, as suggested by Dvali and Gomez. In addition to that, the constituents of such a configuration are understood as loosely confined in a binding harmonic potential. A simple analysis shows that the resolution of a central singularity through quantum physics does not tarnish the classical description, which is bestowed upon this extended self-gravitating system by General Relativity. Finally, we estimate the appearance of an internal horizon as being negligible, because of the suppression of the related probability caused by the large number of virtual gravitons.

Expanding Our Horizons. 1995 Success Stories.

ERIC Educational Resources Information Center

Royce and Royce, Inc., Lancaster, PA.

This booklet profiles 10 former participants in adult basic education (ABE) and literacy programs who have gone on to build successful lives and careers and have been designated outstanding adult students by the Pennsylvania Association for Adult and Continuing Education. The men and women selected as award winners were sponsored by the following…

Expanding Professional Horizons: Increasing Professional Opportunities.

ERIC Educational Resources Information Center

Gooch, Bill G.

Development of human resources is the primary purpose of vocational education, and it is only through continued professional growth that vocational educators can develop and maintain the knowledge, attitudes, skills, and habits needed to assist others in the process of realizing their full potential. The individual and professional development of…

Expanding Horizons in Self-Directed Learning.

ERIC Educational Resources Information Center

Long, Huey B.; And Others

The following papers are included: "Preface" (Huey B. Long); "Self-Directed Learning: Smoke and Mirrors?" (Huey B. Long); "From Self-Culture to Self-Direction: An Historical Analysis of Self-Directed Learning" (Amy D. Rose); "The Link between Self-Directed and Transformative Learning" (Jane Pilling-Cormick);…

Expanding horizons of farming with grass

USDA-ARS?s Scientific Manuscript database

Today’s agriculture and food systems are deeply rooted from the era of cheap energy, an assumption of static climate, and the ability of entities to “externalize” environmental and social costs. The recent collapse of global financial systems has led to more openness to discuss rights and responsib...

Planning horizon affects prophylactic decision-making and epidemic dynamics

PubMed Central

Ridenhour, Benjamin J.; Krone, Stephen M.

2016-01-01

The spread of infectious diseases can be impacted by human behavior, and behavioral decisions often depend implicitly on a planning horizon—the time in the future over which options are weighed. We investigate the effects of planning horizons on epidemic dynamics. We developed an epidemiological agent-based model (along with an ODE analog) to explore the decision-making of self-interested individuals on adopting prophylactic behavior. The decision-making process incorporates prophylaxis efficacy and disease prevalence with the individuals’ payoffs and planning horizon. Our results show that for short and long planning horizons individuals do not consider engaging in prophylactic behavior. In contrast, individuals adopt prophylactic behavior when considering intermediate planning horizons. Such adoption, however, is not always monotonically associated with the prevalence of the disease, depending on the perceived protection efficacy and the disease parameters. Adoption of prophylactic behavior reduces the epidemic peak size while prolonging the epidemic and potentially generates secondary waves of infection. These effects can be made stronger by increasing the behavioral decision frequency or distorting an individual’s perceived risk of infection. PMID:27843714

Nonexistence of degenerate horizons in static vacua and black hole uniqueness

NASA Astrophysics Data System (ADS)

Khuri, Marcus; Woolgar, Eric

2018-02-01

We show that in any spacetime dimension D ≥ 4, degenerate components of the event horizon do not exist in static vacuum configurations with positive cosmological constant. We also show that without a cosmological constant asymptotically flat solutions cannot possess a degenerate horizon component. Several independent proofs are presented. One proof follows easily from differential geometry in the near-horizon limit, while others use Bakry-Émery-Ricci bounds for static Einstein manifolds.

Earth, Meet Pluto: The New Horizons Education and Communications Partnership

NASA Astrophysics Data System (ADS)

Buckley, M.

2015-12-01

The unique partnership between the NASA New Horizons education/communications and public affairs programs tapped into the excitement of visiting an unexplored planet in a new region of the solar system - resulting in unprecedented public participation in and coverage of a planetary mission. With a range of hands-on learning experiences, Web materials and online , the program provided opportunities for students, educators, museums, science centers, the media, Web surfers and other members of the public to ride along on the first mission to Pluto and the Kuiper Belt. The programs leveraged resources, materials and expertise to address a wide range of traditional and nontraditional audiences while providing consistent messages and information on this historic NASA endeavor. The E/C program included a variety of formal lesson plans and learning materials — based on New Horizons science and engineering goals, and aligned with National Research Council's National Science Education Standards — that continue to help students in grades K-12 learn more about science, technology, engineering and mathematics. College students designed and built an actual flight instrument on New Horizons and held internships with the spacecraft integration and test team. New Horizons E/C programs went well beyond the classroom, from a chance for people to send their names to Pluto on board the New Horizons spacecraft before launch, to opportunities for the public to access milestone events and the first-ever close-up views of Pluto in places such as museums, science centers and libraries, TV and the Web — as well as thousands who attended interactive "Plutopalooza" road shows across the country. Teamed with E/C was the public affairs strategy to communicate New Horizons news and messages to media, mission stakeholders, the scientific community and the public. These messages include various aspects of New Horizons, including the progress of the mission and key milestones and achievements

A visual horizon affects steering responses during flight in fruit flies.

PubMed

Caballero, Jorge; Mazo, Chantell; Rodriguez-Pinto, Ivan; Theobald, Jamie C

2015-09-01

To navigate well through three-dimensional environments, animals must in some way gauge the distances to objects and features around them. Humans use a variety of visual cues to do this, but insects, with their small size and rigid eyes, are constrained to a more limited range of possible depth cues. For example, insects attend to relative image motion when they move, but cannot change the optical power of their eyes to estimate distance. On clear days, the horizon is one of the most salient visual features in nature, offering clues about orientation, altitude and, for humans, distance to objects. We set out to determine whether flying fruit flies treat moving features as farther off when they are near the horizon. Tethered flies respond strongly to moving images they perceive as close. We measured the strength of steering responses while independently varying the elevation of moving stimuli and the elevation of a virtual horizon. We found responses to vertical bars are increased by negative elevations of their bases relative to the horizon, closely correlated with the inverse of apparent distance. In other words, a bar that dips far below the horizon elicits a strong response, consistent with using the horizon as a depth cue. Wide-field motion also had an enhanced effect below the horizon, but this was only prevalent when flies were additionally motivated with hunger. These responses may help flies tune behaviors to nearby objects and features when they are too far off for motion parallax. © 2015. Published by The Company of Biologists Ltd.

Thermal excitation spectrum from entanglement in an expanding quantum string

NASA Astrophysics Data System (ADS)

Berges, Jürgen; Floerchinger, Stefan; Venugopalan, Raju

2018-03-01

A surprising result in e+e- collisions is that the particle spectra from the string formed between the expanding quark-antiquark pair have thermal properties even though scatterings appear not to be frequent enough to explain this. We address this problem by considering the finite observable interval of a relativistic quantum string in terms of its reduced density operator by tracing over the complement region. We show how quantum entanglement in the presence of a horizon in spacetime for the causal transfer of information leads locally to a reduced mixed-state density operator. For very early proper time τ, we show that the entanglement entropy becomes extensive and scales with the rapidity. At these early times, the reduced density operator is of thermal form, with an entanglement temperature Tτ = ħ / (2 πkB τ), even in the absence of any scatterings.

ExpandED Options: Learning beyond High School Walls

ERIC Educational Resources Information Center

ExpandED Schools, 2014

2014-01-01

Through ExpandED Options by TASC, New York City high school students get academic credit for learning career-related skills that lead to paid summer jobs. Too many high school students--including those most likely to drop out--are bored or see classroom learning as irrelevant. ExpandED Options students live the connection between mastering new…

Tunneling from the past horizon

NASA Astrophysics Data System (ADS)

Kang, Subeom; Yeom, Dong-han

2018-04-01

We investigate a tunneling and emission process of a thin-shell from a Schwarzschild black hole, where the shell was initially located beyond the Einstein-Rosen bridge and finally appears at the right side of the Penrose diagram. In order to obtain such a solution, we should assume that the areal radius of the black hole horizon increases after the tunneling. Hence, there is a parameter range such that the tunneling rate is exponentially enhanced, rather than suppressed. We may have two interpretations regarding this. First, such a tunneling process from the past horizon is improbable by physical reasons; second, such a tunneling is possible in principle, but in order to obtain a stable Einstein-Rosen bridge, one needs to restrict the parameter spaces. If such a process is allowed, this can be a nonperturbative contribution to Einstein-Rosen bridges as well as eternal black holes.

Estimation of the Horizon in Photographed Outdoor Scenes by Human and Machine

PubMed Central

Herdtweck, Christian; Wallraven, Christian

2013-01-01

We present three experiments on horizon estimation. In Experiment 1 we verify the human ability to estimate the horizon in static images from only visual input. Estimates are given without time constraints with emphasis on precision. The resulting estimates are used as baseline to evaluate horizon estimates from early visual processes. Stimuli are presented for only ms and then masked to purge visual short-term memory and enforcing estimates to rely on early processes, only. The high agreement between estimates and the lack of a training effect shows that enough information about viewpoint is extracted in the first few hundred milliseconds to make accurate horizon estimation possible. In Experiment 3 we investigate several strategies to estimate the horizon in the computer and compare human with machine “behavior” for different image manipulations and image scene types. PMID:24349073

Air Monitoring Data for BP Spill/Deepwater Horizon

EPA Pesticide Factsheets

The Deepwater Horizon oil spill (also referred to as the BP oil spill) began on 20 April 2010 in the Gulf of Mexico on the BP-operated Macondo Prospect. Following the explosion and sinking of the Deepwater Horizon oil rig, a sea-floor oil gusher flowed for 87 days, until it was capped on 15 July 2010.In response to the BP oil spill, EPA sampled air, water, sediment, and waste generated by the cleanup operations.

Water Sampling Data for BP Spill/Deepwater Horizon

EPA Pesticide Factsheets

The Deepwater Horizon oil spill (also referred to as the BP oil spill) began on 20 April 2010 in the Gulf of Mexico on the BP-operated Macondo Prospect. Following the explosion and sinking of the Deepwater Horizon oil rig, a sea-floor oil gusher flowed for 87 days, until it was capped on 15 July 2010.In response to the BP oil spill, EPA sampled air, water, sediment, and waste generated by the cleanup operations.

Waste Sampling Data for BP Spill/Deepwater Horizon

EPA Pesticide Factsheets

The Deepwater Horizon oil spill (also referred to as the BP oil spill) began on 20 April 2010 in the Gulf of Mexico on the BP-operated Macondo Prospect. Following the explosion and sinking of the Deepwater Horizon oil rig, a sea-floor oil gusher flowed for 87 days, until it was capped on 15 July 2010.In response to the BP oil spill, EPA sampled air, water, sediment, and waste generated by the cleanup operations.

Air Sampling Data for BP Spill/Deepwater Horizon

EPA Pesticide Factsheets

The Deepwater Horizon oil spill (also referred to as the BP oil spill) began on 20 April 2010 in the Gulf of Mexico on the BP-operated Macondo Prospect. Following the explosion and sinking of the Deepwater Horizon oil rig, a sea-floor oil gusher flowed for 87 days, until it was capped on 15 July 2010.In response to the BP oil spill, EPA sampled air, water, sediment, and waste generated by the cleanup operations.

Sediment Sampling Data for BP Spill/Deepwater Horizon

EPA Pesticide Factsheets

The Deepwater Horizon oil spill (also referred to as the BP oil spill) began on 20 April 2010 in the Gulf of Mexico on the BP-operated Macondo Prospect. Following the explosion and sinking of the Deepwater Horizon oil rig, a sea-floor oil gusher flowed for 87 days, until it was capped on 15 July 2010.In response to the BP oil spill, EPA sampled air, water, sediment, and waste generated by the cleanup operations.

New Horizons Event: The First Mission to the Pluto System

NASA Image and Video Library

2014-08-25

Audience members view slides from a presentation by Dr. Jim Green, Dr. Ed Stone, and Dr. Alan Stern at the "New Horizons: The First Mission to the Pluto System and the Kuiper Belt" Event at NASA Headquarters in Washington, DC Monday, August 25, 2014. They discussed how the first images of Pluto and its moons would be captured by the New Horizons spacecraft during a five month long reconnaissance flyby study starting in the summer of 2015. New Horizons launched on January 19, 2006 and is scheduled to make its closest approach to Pluto on July 14, 2015. Photo Credit: (NASA/Aubrey Gemignani)

New Horizons Event: The First Mission to the Pluto System

NASA Image and Video Library

2014-08-25

Dr. Jim Green, Dr. Ed Stone, and Dr. Alan Stern speak on a panel at the "New Horizons: The First Mission to the Pluto System and the Kuiper Belt" Event at NASA Headquarters in Washington, DC Monday, August 25, 2014. They discussed how the first images of Pluto and its moons would be captured by the New Horizons spacecraft during a five month long reconnaissance flyby study starting in the summer of 2015. New Horizons launched on January 19, 2006 and is scheduled to make its closest approach to Pluto on July 14, 2015. Photo Credit: (NASA/Aubrey Gemignani)

New Horizons Event: The First Mission to the Pluto System

NASA Image and Video Library

2014-08-25

Dr. Jim Green, Director of NASA’s Planetary Division, speaks on a panel at the "New Horizons: The First Mission to the Pluto System and the Kuiper Belt" Event at NASA Headquarters in Washington, DC Monday, August 25, 2014. Scientists discussed how the first images of Pluto and its moons would be captured by the New Horizons spacecraft during a five month long reconnaissance flyby study starting in the summer of 2015. New Horizons launched on January 19, 2006 and is scheduled to make its closest approach to Pluto on July 14, 2015. Photo Credit: (NASA/Aubrey Gemignani)

Infrared horizon sensor modeling for attitude determination and control: Analysis and mission experience

NASA Technical Reports Server (NTRS)

Phenneger, M. C.; Singhal, S. P.; Lee, T. H.; Stengle, T. H.

1985-01-01

The work performed by the Attitude Determination and Control Section at the National Aeronautics and Space Administration/Goddard Space Flight Center in analyzing and evaluating the performance of infrared horizon sensors is presented. The results of studies performed during the 1960s are reviewed; several models for generating the Earth's infrared radiance profiles are presented; and the Horizon Radiance Modeling Utility, the software used to model the horizon sensor optics and electronics processing to computer radiance-dependent attitude errors, is briefly discussed. Also provided is mission experience from 12 spaceflight missions spanning the period from 1973 to 1984 and using a variety of horizon sensing hardware. Recommendations are presented for future directions for the infrared horizon sensing technology.

HIGHER HORIZONS. PROGRESS REPORT.

ERIC Educational Resources Information Center

LANDERS, JACOB

HUMAN TALENT IS MUCH TOO PRECIOUS TO BE STIFLED AND WASTED. THEREFORE, IT SHOULD BE SOUGHT OUT, UNCOVERED, AND DEVELOPED IN THE SCHOOLS. HIGHER HORIZONS IS A QUEST FOR THE KIND OF EDUCATION WHICH, ADJUSTED TO THE NEEDS OF DISADVANTAGED CHILDREN, WILL ENABLE THEM TO COMPETE WITH OTHER CHILDREN ON AN EQUAL BASIS AND TO RECEIVE A FAIR SHARE OF THE…

New Horizons Risk Communication Strategy, Planning, Implementation, and Lessons Learned

NASA Technical Reports Server (NTRS)

Dawson, Sandra A.

2006-01-01

This paper discusses the risk communication goals, strategy, planning process and product development for the New Horizons mission, including lessons from the Cassini mission that were applied in that effort, and presents lessons learned from the New Horizons effort that could be applicable to future missions.

Optical Navigation Preparations for New Horizons Pluto Flyby

NASA Technical Reports Server (NTRS)

Owen, William M., Jr.; Dumont, Philip J.; Jackman, Coralie D.

2012-01-01

The New Horizons spacecraft will encounter Pluto and its satellites in July 2015. As was the case for the Voyager encounters with Jupiter, Saturn, Uranus and Neptune, mission success will depend heavily on accurate spacecraft navigation, and accurate navigation will be impossible without the use of pictures of the Pluto system taken by the onboard cameras. We describe the preparations made by the New Horizons optical navigators: picture planning, image processing algorithms, software development and testing, and results from in-flight imaging.

Post-School Horizons: New Zealand's Neo-Liberal Generation in Transition

ERIC Educational Resources Information Center

Nairn, Karen; Higgins, Jane; Ormond, Adreanne

2007-01-01

Dominant conceptions of the world infuse educational experiences for young people in implicit rather than explicit ways--through becoming, as Stuart Hall argues, "the horizon of the taken-for-granted". In this article we explore these horizons as experienced by New Zealand's neo-liberal generation, currently "in transition"…

Nitrate retention capacity of milldam-impacted legacy sediments and relict A horizon soils

NASA Astrophysics Data System (ADS)

Weitzman, Julie N.; Kaye, Jason P.

2017-05-01

While eutrophication is often attributed to contemporary nutrient pollution, there is growing evidence that past practices, like the accumulation of legacy sediment behind historic milldams, are also important. Given their prevalence, there is a critical need to understand how N flows through, and is retained in, legacy sediments to improve predictions and management of N transport from uplands to streams in the context of climatic variability and land-use change. Our goal was to determine how nitrate (NO3-) is cycled through the soil of a legacy-sediment-strewn stream before and after soil drying. We extracted 10.16 cm radius intact soil columns that extended 30 cm into each of the three significant soil horizons at Big Spring Run (BSR) in Lancaster, Pennsylvania: surface legacy sediment characterized by a newly developing mineral A horizon soil, mid-layer legacy sediment consisting of mineral B horizon soil and a dark, organic-rich, buried relict A horizon soil. Columns were first preincubated at field capacity and then isotopically labeled nitrate (15NO3-) was added and allowed to drain to estimate retention. The columns were then air-dried and subsequently rewet with N-free water and allowed to drain to quantify the drought-induced loss of 15NO3- from the different horizons. We found the highest initial 15N retention in the mid-layer legacy sediment (17 ± 4 %) and buried relict A soil (14 ± 3 %) horizons, with significantly lower retention in the surface legacy sediment (6 ± 1 %) horizon. As expected, rewetting dry soil resulted in 15N losses in all horizons, with the greatest losses in the buried relict A horizon soil, followed by the mid-layer legacy sediment and surface legacy sediment horizons. The 15N remaining in the soil following the post-drought leaching was highest in the mid-layer legacy sediment, intermediate in the surface legacy sediment, and lowest in the buried relict A horizon soil. Fluctuations in the water table at BSR which affect

A Fusion of Horizons: Students' Encounters with "Will and Wave"

ERIC Educational Resources Information Center

Myers, James L.

2006-01-01

In a case study, I applied philosophical hermeneutic principles in an advanced level EFL writing class in Taiwan. A "fusion of horizons" occurs at the junction of two intertwined interpretations: one from our socio-historical tradition and the other from our experience of novel phenomena. I explored students' hermeneutic horizons in…

Finding KBO flyby targets for New Horizons

NASA Astrophysics Data System (ADS)

Spencer, John; Trilling, David; Buie, Marc; Parker, Alex; Tholen, David; Stern, S. Alan

2014-08-01

We propose to continue the search for Kuiper Belt Objects (KBOs) that can be reached by the New Horizons spacecraft after its 2015 Pluto flyby, by following up on KBOs discovered in 2014A. The first flyby of a small (~50 km) KBO would revolutionize our understanding of KBOs, providing information that can be extrapolated to hundreds of thousands of similar KBOs. Our 2011 search discovered two objects that could be targeted with less than twice the fuel that New Horizons has available, during excellent seeing, but seeing was insufficient to achieve this depth over the entire search area in 2012 or 2013. Deepening the search with time allocated in 2014A, taking advantage of lower star density and the shrinking search area, has a chance of finding a targetable object given sufficiently good seeing, especially with Hyper Suprime Cam. 2014B follow-up is essential to produce orbits good enough to determine targetability, and allow recovery in 2015. We will also continue to refine the orbits of other previously discovered objects, including ones that can be observed from a distance by New Horizons on its passage through the Kuiper Belt.

New Horizons in Education, 2000.

ERIC Educational Resources Information Center

Ho, Kwok Keung, Ed.

2000-01-01

This document contains the May and November 2000 issues of "New Horizons in Education," with articles in English and Chinese. The May issue includes the following articles: "A Key to Successful Environmental Education: Teacher Trainees' Attitude, Behaviour, and Knowledge" (Kevin Chung Wai Lui, Eric Po Keung Tsang, Sing Lai…

Transport of four pharmaceuticals in different horizons of three soil types

NASA Astrophysics Data System (ADS)

Kodesova, Radka; Svatkova, Paula; Klement, Ales; Jaksik, Ondrej; Golovko, Oksana; Fer, Miroslav; Kocarek, Martin; Nikodem, Antonin; Grabic, Roman

2015-04-01

Soil structure, which varies in different soil types and the horizons of these soil types, has a significant impact on water flow and contaminant transport in soils. Transport of many contaminants is in addition strongly influenced by their sorption on soil particles. Transport of four pharmaceuticals (sulfamethoxazole, trimethoprim, atenolol and carbamazepine) was studied in soil columns (a diameter of 10.5 cm and a height of 13 cm) taken from all diagnostic horizons of three different soil types (Haplic Luvisol, Greyic Phaeozem and Haplic Cambisol). The irrigation by water contaminated by a mixture of all four compounds followed by ponding infiltration of distilled water was simulated and water outflow and solute concentrations from the bottom of the soil sample was monitored in time. The highest infiltration rates were observed for soil samples from the Bt horizons of the Greyic Phaeozem that exhibited prismatic structure, followed by rates observed in the Ap horizons of the Haplic Luvisol, Greyic Phaeozem and Haplic Cambisol (due to their granular soil structure and presence of root channels). The lowest infiltration rate was measured for the Bw horizon of the Haplic Cambisol, which had a poorly developed soil structure and a low fraction of macropores. Compound discharge was however also highly affected by their sorption on solids. The highest mobility was observed for sulfamethoxazole followed by carbamazepine atenolol and trimethoprim, which corresponds to measured sorption isotherms. Mobility of ionizable compounds in different soil samples was influenced by pH (i.e. degree and form of their ionization) and sites available for absorption. Mobility of sulfamethoxazole decreased with decreasing pH (i.e. the largest sorption measured in horizons of the Haplic Cambisol). While mobility of atenolol and trimethoprim decreased with increasing base cation saturation, and with increasing organic matter content for carbamazepine. As result of both affects (i.e. soil

Gravitational lensing and ghost images in the regular Bardeen no-horizon spacetimes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schee, Jan; Stuchlík, Zdeněk, E-mail: jan.schee@fpf.slu.cz, E-mail: zdenek.stuchlik@fpf.slu.cz

We study deflection of light rays and gravitational lensing in the regular Bardeen no-horizon spacetimes. Flatness of these spacetimes in the central region implies existence of interesting optical effects related to photons crossing the gravitational field of the no-horizon spacetimes with low impact parameters. These effects occur due to existence of a critical impact parameter giving maximal deflection of light rays in the Bardeen no-horizon spacetimes. We give the critical impact parameter in dependence on the specific charge of the spacetimes, and discuss 'ghost' direct and indirect images of Keplerian discs, generated by photons with low impact parameters. The ghostmore » direct images can occur only for large inclination angles of distant observers, while ghost indirect images can occur also for small inclination angles. We determine the range of the frequency shift of photons generating the ghost images and determine distribution of the frequency shift across these images. We compare them to those of the standard direct images of the Keplerian discs. The difference of the ranges of the frequency shift on the ghost and direct images could serve as a quantitative measure of the Bardeen no-horizon spacetimes. The regions of the Keplerian discs giving the ghost images are determined in dependence on the specific charge of the no-horizon spacetimes. For comparison we construct direct and indirect (ordinary and ghost) images of Keplerian discs around Reissner-Nördström naked singularities demonstrating a clear qualitative difference to the ghost direct images in the regular Bardeen no-horizon spacetimes. The optical effects related to the low impact parameter photons thus give clear signature of the regular Bardeen no-horizon spacetimes, as no similar phenomena could occur in the black hole or naked singularity spacetimes. Similar direct ghost images have to occur in any regular no-horizon spacetimes having nearly flat central region.« less

Output-feedback control of combined sewer networks through receding horizon control with moving horizon estimation

NASA Astrophysics Data System (ADS)

Joseph-Duran, Bernat; Ocampo-Martinez, Carlos; Cembrano, Gabriela

2015-10-01

An output-feedback control strategy for pollution mitigation in combined sewer networks is presented. The proposed strategy provides means to apply model-based predictive control to large-scale sewer networks, in-spite of the lack of measurements at most of the network sewers. In previous works, the authors presented a hybrid linear control-oriented model for sewer networks together with the formulation of Optimal Control Problems (OCP) and State Estimation Problems (SEP). By iteratively solving these problems, preliminary Receding Horizon Control with Moving Horizon Estimation (RHC/MHE) results, based on flow measurements, were also obtained. In this work, the RHC/MHE algorithm has been extended to take into account both flow and water level measurements and the resulting control loop has been extensively simulated to assess the system performance according different measurement availability scenarios and rain events. All simulations have been carried out using a detailed physically based model of a real case-study network as virtual reality.

Soil water dynamics during precipitation in genetic horizons of Retisol

NASA Astrophysics Data System (ADS)

Zaleski, Tomasz; Klimek, Mariusz; Kajdas, Bartłomiej

2017-04-01

Retisols derived from silty deposits dominate in the soil cover of the Carpathian Foothills. The hydrophysical properties of these are determined by the grain-size distribution of the parent material and the soil's "primary" properties shaped in the deposition process. The other contributing factors are the soil-forming processes, such as lessivage (leaching of clay particles), and the morphogenetic processes that presently shape the relief. These factors are responsible for the "secondary" differentiation of hydrophysical properties across the soil profile. Both the primary and secondary hydrophysical properties of soils (the rates of water retention, filtration and infiltration, and the moisture distribution over the soil profile) determine their ability to take in rainfall, the amount of rainwater taken in, and the ways of its redistribution. The aims of the study, carried out during 2015, were to investigate the dynamics of soil moisture in genetic horizons of Retisol derived from silty deposits and to recognize how fast and how deep water from precipitation gets into soil horizons. Data of soil moisture were measured using 5TM moisture and temperature sensor and collected by logger Em50 (Decagon Devices USA). Data were captured every 10 minutes from 6 sensors at depths: - 10 cm, 20 cm, 40 cm, 60 cm and 80 cm. Precipitation data come from meteorological station situated 50 m away from the soil profile. Two zones differing in the type of water regime were distinguished in Retisol: an upper zone comprising humic and eluvial horizons, and a lower zone consisting of illuvial and parent material horizons. The upper zone shows smaller retention of water available for plants, and relatively wide fluctuations in moisture content, compared to the lower zone. The lower zone has stable moisture content during the vegetation season, with values around the water field capacity. Large changes in soil moisture were observed while rainfall. These changes depend on the volume

Flying by Ear: Blind Flight with a Music-Based Artificial Horizon

NASA Technical Reports Server (NTRS)

Simpson, Brian D.; Brungart, Douglas S.; Dallman, Ronald C.; Yasky, Richard J., Jr.; Romigh, Griffin

2008-01-01

Two experiments were conducted in actual flight operations to evaluate an audio artificial horizon display that imposed aircraft attitude information on pilot-selected music. The first experiment examined a pilot's ability to identify, with vision obscured, a change in aircraft roll or pitch, with and without the audio artificial horizon display. The results suggest that the audio horizon display improves the accuracy of attitude identification overall, but differentially affects response time across conditions. In the second experiment, subject pilots performed recoveries from displaced aircraft attitudes using either standard visual instruments, or, with vision obscured, the audio artificial horizon display. The results suggest that subjects were able to maneuver the aircraft to within its safety envelope. Overall, pilots were able to benefit from the display, suggesting that such a display could help to improve overall safety in general aviation.

Thermal excitation spectrum from entanglement in an expanding quantum string

DOE PAGES

Berges, Jurgen; Floerchinger, Stefan; Venugopalan, Raju

2018-01-31

Here, a surprising result in e +e - collisions is that the particle spectra from the string formed between the expanding quark-antiquark pair have thermal properties even though scatterings appear not to be frequent enough to explain this. We address this problem by considering the finite observable interval of a relativistic quantum string in terms of its reduced density operator by tracing over the complement region. We show how quantum entanglement in the presence of a horizon in spacetime for the causal transfer of information leads locally to a reduced mixed-state density operator. For very early proper time τ, wemore » show that the entanglement entropy becomes extensive and scales with the rapidity. At these early times, the reduced density operator is of thermal form, with an entanglement temperature Tτ = h(2πk Bτ), even in the absence of any scatterings.« less

Thermal excitation spectrum from entanglement in an expanding quantum string

DOE Office of Scientific and Technical Information (OSTI.GOV)

Berges, Jurgen; Floerchinger, Stefan; Venugopalan, Raju

Here, a surprising result in e +e - collisions is that the particle spectra from the string formed between the expanding quark-antiquark pair have thermal properties even though scatterings appear not to be frequent enough to explain this. We address this problem by considering the finite observable interval of a relativistic quantum string in terms of its reduced density operator by tracing over the complement region. We show how quantum entanglement in the presence of a horizon in spacetime for the causal transfer of information leads locally to a reduced mixed-state density operator. For very early proper time τ, wemore » show that the entanglement entropy becomes extensive and scales with the rapidity. At these early times, the reduced density operator is of thermal form, with an entanglement temperature Tτ = h(2πk Bτ), even in the absence of any scatterings.« less

New Horizons Mission to Pluto

NASA Technical Reports Server (NTRS)

Delgado, Luis G.

2011-01-01

This slide presentation reviews the trajectory that will take the New Horizons Mission to Pluto. Included are photographs of the spacecraft, the launch vehicle, the assembled vehicle as it is being moved to the launch pad and the launch. Also shown are diagrams of the assembled parts with identifying part names.

Priority Questions and Horizon Scanning for Conservation: A Comparative Study

PubMed Central

Kark, Salit; Sutherland, William J.; Shanas, Uri; Klass, Keren; Achisar, Hila; Dayan, Tamar; Gavrieli, Yael; Justo-Hanani, Ronit; Mandelik, Yael; Orion, Nir; Pargament, David; Portman, Michelle; Reisman-Berman, Orna; Safriel, Uriel N.; Schaffer, Gad; Steiner, Noa; Tauber, Israel; Levin, Noam

2016-01-01

Several projects aimed at identifying priority issues for conservation with high relevance to policy have recently been completed in several countries. Two major types of projects have been undertaken, aimed at identifying (i) policy-relevant questions most imperative to conservation and (ii) horizon scanning topics, defined as emerging issues that are expected to have substantial implications for biodiversity conservation and policy in the future. Here, we provide the first overview of the outcomes of biodiversity and conservation-oriented projects recently completed around the world using this framework. We also include the results of the first questions and horizon scanning project completed for a Mediterranean country. Overall, the outcomes of the different projects undertaken (at the global scale, in the UK, US, Canada, Switzerland and in Israel) were strongly correlated in terms of the proportion of questions and/or horizon scanning topics selected when comparing different topic areas. However, some major differences were found across regions. There was large variation among regions in the percentage of proactive (i.e. action and response oriented) versus descriptive (non-response oriented) priority questions and in the emphasis given to socio-political issues. Substantial differences were also found when comparing outcomes of priority questions versus horizon scanning projects undertaken for the same region. For example, issues related to climate change, human demography and marine ecosystems received higher priority as horizon scanning topics, while ecosystem services were more emphasized as current priority questions. We suggest that future initiatives aimed at identifying priority conservation questions and horizon scanning topics should allow simultaneous identification of both current and future priority issues, as presented here for the first time. We propose that further emphasis on social-political issues should be explicitly integrated into future

Confronting Space Debris: Strategies and Warnings from Comparable Examples Including Deepwater Horizon

DTIC Science & Technology

2010-01-01

Horizon (DH) was an ultra deepwater , semisubmers- ible offshore drilling rig contracted to BP by its owner, Transocean. The rig was capable of...Warnings from Comparable Examples Including Deepwater Horizon 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) 5d. PROJECT...research quality and objectivity. StrategieS and WarningS from Comparable exampleS inCluding deepWater Horizon Confronting SpaCe DebriS dave baiocchi

Pre-Hawking radiation cannot prevent the formation of apparent horizon

NASA Astrophysics Data System (ADS)

Chen, Pisin; Unruh, William G.; Wu, Chih-Hung; Yeom, Dong-Han

2018-03-01

As an attempt to solve the black hole information loss paradox, recently there has been the suggestion that, due to semiclassical effects, a pre-Hawking radiation must exist during the gravitational collapse of matter, which in turn prevents the apparent horizon from forming. Assuming the pre-Hawking radiation does exist, here we argue the opposite. First we note that the stress energy tensor near the horizon for the pre-Hawking radiation is far too small to do anything to the motion of a collapsing shell. Thus the shell will always cross the apparent horizon within a finite proper time. Moreover, the amount of energy that can be radiated must be less than half of the total initial energy (if the particle starts at rest at infinity) before the shell becomes a null shell and cannot radiate any more without becoming tachyonic. We conclude that for any gravitational collapsing process within Einstein gravity and semiclassical quantum field theory, the formation of the apparent horizon is inevitable. Pre-Hawking radiation is therefore not a valid solution to the information paradox.

Modeling of roll/pitch determination with horizon sensors - Oblate Earth

NASA Astrophysics Data System (ADS)

Hablani, Hari B.

Model calculations are presented of roll/pitch determinations for oblate Earth, with horizon sensors. Two arrangements of a pair of horizon sensors are considered: left and right of the velocity vactor (i.e., along the pitch axis), and aft and forward (along the roll axis). Two approaches are used to obtain the roll/pitch oblateness corrections: (1) the crossing point approach, where the two crossings of the horizon sensor's scan and the earth's horizon are determined, and (2) by decomposing the angular deviation of the geocentric normal from the geodetic normal into roll and pitch components. It is shown that the two approaches yield essentially the same corrections if two sensors are used simultaneously. However, if the spacecraft is outfitted with only one sensor, the oblateness correction about one axis is far different from that predicted by the geocentric/geodetic angular deviation approach. In this case, the corrections may be calculated on ground for the sensor location under consideration and stored in the flight computer, using the crossing point approach.

Horizon geometry for Kerr black holes with synchronized hair

NASA Astrophysics Data System (ADS)

Delgado, Jorge F. M.; Herdeiro, Carlos A. R.; Radu, Eugen

2018-06-01

We study the horizon geometry of Kerr black holes (BHs) with scalar synchronized hair [1], a family of solutions of the Einstein-Klein-Gordon system that continuously connects to vacuum Kerr BHs. We identify the region in parameter space wherein a global isometric embedding in Euclidean 3-space, E3, is possible for the horizon geometry of the hairy BHs. For the Kerr case, such embedding is possible iff the horizon dimensionless spin jH (which equals the total dimensionless spin, j ), the sphericity s and the horizon linear velocity vH are smaller than critical values, j(S ),s(S ),vH(S ), respectively. For the hairy BHs, we find that jH

Finite horizon optimum control with and without a scrap value

NASA Astrophysics Data System (ADS)

Neck, R.; Blueschke-Nikolaeva, V.; Blueschke, D.

2017-06-01

In this paper, we study the effects of scrap values on the solutions of optimal control problems with finite time horizon. We show how to include a scrap value, either for the state variables or for the state and the control variables, in the OPTCON2 algorithm for the optimal control of dynamic economic systems. We ask whether the introduction of a scrap value can serve as a substitute for an infinite horizon in economic policy optimization problems where the latter option is not available. Using a simple numerical macroeconomic model, we demonstrate that the introduction of a scrap value cannot induce control policies which can be expected for problems with an infinite time horizon.

New Horizons: Bridge to the Beginning - to Pluto and Beyond

NASA Astrophysics Data System (ADS)

Weir, H. M.; Hallau, K. G.; Seaton, P.; Beisser, K.; New Horizons Education; Public Outreach Team

2010-12-01

Launched on Jan. 19, 2006, NASA’s New Horizons mission to Pluto and the Kuiper Belt will help us understand worlds at the edge of our solar system by making the first reconnaissance of Pluto and Charon - a "double planet" and the last planet in our solar system to be visited by spacecraft. However, New Horizons’ closest approach to Pluto will not occur until July 14, 2015, and the majority of the craft's time over the next 5 years will be spent in "hibernation." The Education and Public Outreach (EPO) team, however, will not be hibernating as we wait for New Horizons to reach its destination. With three distinct tools-- Educator Fellows, online learning modules and a planetarium program--the team seeks to excite and engage teachers, students and the public with information about the journey to Pluto and beyond. In the past year, the specially selected educators who participate as New Horizons Educator Fellows have trained more than 1,000 teachers across the U.S. on the New Horizons mission and the science behind it. Thousands more students, parents, educators, and citizens have learned about New Horizons from the mission's scientists, engineers and outreach professionals. New Horizons Fellows also distribute another EPO tool: online learning modules. These classroom-ready learning modules consist of educator guides, student handouts, detailed activities, and potential adaptations for students with special needs or disabilities. Some also offer online interactives to convey complex and dynamic concepts. The modules are web-accessible for both students and teachers, and are aligned with relevant national standards. The third tool is a highly visual way to engage the general public and supplement educational programs: a planetarium program that highlights the New Horizons mission from launch to destination Pluto. This program focuses on the engineering design of the spacecraft, with a focus on the concept of the electromagnetic spectrum. In the unique environment

Coordinated control of micro-grid based on distributed moving horizon control.

PubMed

Ma, Miaomiao; Shao, Liyang; Liu, Xiangjie

2018-05-01

This paper proposed the distributed moving horizon coordinated control scheme for the power balance and economic dispatch problems of micro-grid based on distributed generation. We design the power coordinated controller for each subsystem via moving horizon control by minimizing a suitable objective function. The objective function of distributed moving horizon coordinated controller is chosen based on the principle that wind power subsystem has the priority to generate electricity while photovoltaic power generation coordinates with wind power subsystem and the battery is only activated to meet the load demand when necessary. The simulation results illustrate that the proposed distributed moving horizon coordinated controller can allocate the output power of two generation subsystems reasonably under varying environment conditions, which not only can satisfy the load demand but also limit excessive fluctuations of output power to protect the power generation equipment. Copyright © 2018 ISA. Published by Elsevier Ltd. All rights reserved.

A horizon scan of global conservation issues for 2013.

PubMed

Sutherland, William J; Bardsley, Sarah; Clout, Mick; Depledge, Michael H; Dicks, Lynn V; Fellman, Liz; Fleishman, Erica; Gibbons, David W; Keim, Brandon; Lickorish, Fiona; Margerison, Ceri; Monk, Kathryn A; Norris, Kenneth; Peck, Lloyd S; Prior, Stephanie V; Scharlemann, Jörn P W; Spalding, Mark D; Watkinson, Andrew R

2013-01-01

This paper presents the findings of our fourth annual horizon-scanning exercise, which aims to identify topics that increasingly may affect conservation of biological diversity. The 15 issues were identified via an iterative, transferable process by a team of professional horizon scanners, researchers, practitioners, and a journalist. The 15 topics include the commercial use of antimicrobial peptides, thorium-fuelled nuclear power, and undersea oil production. Copyright © 2012 Elsevier Ltd. All rights reserved.

Constrained field theories on spherically symmetric spacetimes with horizons

NASA Astrophysics Data System (ADS)

Fernandes, Karan; Lahiri, Amitabha; Ghosh, Suman

2017-02-01

We apply the Dirac-Bergmann algorithm for the analysis of constraints to gauge theories defined on spherically symmetric black hole backgrounds. We find that the constraints for a given theory are modified on such spacetimes through the presence of additional contributions from the horizon. As a concrete example, we consider the Maxwell field on a black hole background, and determine the role of the horizon contributions on the dynamics of the theory.

NASA's New Horizons Pluto Mission: Continuing Voyager's Legacy o

NASA Image and Video Library

2014-08-25

Dr. John Spencer, senior scientist at the Southwest Research Institute in Boulder, Colorado, speaks during a panel discussion at the "NASA's New Horizons Pluto Mission: Continuing Voyager's Legacy of Exploration" event on Monday, August, 25, 2014, in the James E. Webb Auditorium at NASA Headquarters in Washington, DC. The panelists gave their accounts of Voyager's encounter with Neptune and discussed their current assignments on NASA's New Horizons mission to Pluto. Photo Credit: (NASA/Joel Kowsky)

NASA's New Horizons Pluto Mission: Continuing Voyager's Legacy o

NASA Image and Video Library

2014-08-25

Dr. Fran Bagenal, senior scientist at the University of Colorado, speaks during a panel discussion at the "NASA's New Horizons Pluto Mission: Continuing Voyager's Legacy of Exploration" event on Monday, August, 25, 2014, in the James E. Webb Auditorium at NASA Headquarters in Washington, DC. The panelists gave their accounts of Voyager's encounter with Neptune and discussed their current assignments on NASA's New Horizons mission to Pluto. Photo Credit: (NASA/Joel Kowsky)

NASA's New Horizons Pluto Mission: Continuing Voyager's Legacy o

NASA Image and Video Library

2014-08-25

Dr. Fran Bagenal, senior scientist at the University of Colorado, far right, speaks during a panel discussion at the "NASA's New Horizons Pluto Mission: Continuing Voyager's Legacy of Exploration" event on Monday, August, 25, 2014, in the James E. Webb Auditorium at NASA Headquarters in Washington, DC. The panelists gave their accounts of Voyager's encounter with Neptune and discussed their current assignments on NASA's New Horizons mission to Pluto. Photo Credit: (NASA/Joel Kowsky)

NASA's New Horizons Pluto Mission: Continuing Voyager's Legacy o

NASA Image and Video Library

2014-08-25

Dr. Bonnie Buratti, senior scientist at NASA's Jet Propultion Laboratory, speaks during a panel discussion at the "NASA's New Horizons Pluto Mission: Continuing Voyager's Legacy of Exploration" event on Monday, August, 25, 2014, in the James E. Webb Auditorium at NASA Headquarters in Washington, DC. The panelists gave their accounts of Voyager's encounter with Neptune and discussed their current assignments on NASA's New Horizons mission to Pluto. Photo Credit: (NASA/Joel Kowsky)

The cost savings of expanding Medicaid eligibility to include currently uninsured homeless adults with substance use disorders.

PubMed

Zur, Julia; Mojtabai, Ramin; Li, Suhui

2014-04-01

Following the June 2012 Supreme Court ruling that states are no longer mandated to expand their Medicaid programs in 2014 as part of the Affordable Care Act, many states plan to opt out of the expansion, citing affordability as their primary concern. In response to this controversy, the present study evaluated the cost savings of expanding Medicaid coverage to include currently ineligible homeless adults with substance use disorders, a subset of the population that incurs some of the greatest societal costs and is disproportionately impacted by uninsurance. Using a time horizon of 7 years, separate analyses were conducted for state and federal governments, and then a final analysis evaluated the combined costs for the other two models. Results of the study demonstrate that, although the expansion will be associated with a net cost when combining state and federal expenses and savings, states will experience tremendous savings if they choose to participate.

Dynamical AdS strings across horizons

DOE PAGES

Ishii, Takaaki; Murata, Keiju

2016-03-01

We examine the nonlinear classical dynamics of a fundamental string in anti-deSitter spacetime. The string is dual to the flux tube between an external quark-antiquark pair in $N = 4$ super Yang-Mills theory. We perturb the string by shaking the endpoints and compute its time evolution numerically. We find that with sufficiently strong perturbations the string continues extending and plunges into the Poincare´ horizon. In the evolution, effective horizons are also dynamically created on the string worldsheet. The quark and antiquark are thus causally disconnected, and the string transitions to two straight strings. The forces acting on the endpoints vanishmore » with a power law whose slope depends on the perturbations. Lastly, the condition for this transition to occur is that energy injection exceeds the static energy between the quark-antiquark pair.« less

The Pluto system after the New Horizons flyby

NASA Astrophysics Data System (ADS)

Olkin, Catherine B.; Ennico, Kimberly; Spencer, John

2017-10-01

In July 2015, NASA's New Horizons mission performed a flyby of Pluto, revealing details about the geology, surface composition and atmospheres of this world and its moons that are unobtainable from Earth. With a resolution as small as 80 metres per pixel, New Horizons' images identified a large number of surface features, including a large basin filled with glacial ices that appear to be undergoing convection. Maps of surface composition show latitudinal banding, with non-volatile material dominating the equatorial region and volatile ices at mid- and polar latitudes. This pattern is driven by the seasonal cycle of solar insolation. New Horizons' atmospheric investigation found the temperature of Pluto's upper atmosphere to be much cooler than previously modelled. Images of forward-scattered sunlight revealed numerous haze layers extending up to 200 km from the surface. These discoveries have transformed our understanding of icy worlds in the outer Solar System, demonstrating that even at great distances from the Sun, worlds can have active geologic processes. This Review addresses our current understanding of the Pluto system and places it in context with previous investigations. 

Towards Assessing the Human Trajectory Planning Horizon

PubMed Central

Nitsch, Verena; Meinzer, Dominik; Wollherr, Dirk

2016-01-01

Mobile robots are envisioned to cooperate closely with humans and to integrate seamlessly into a shared environment. For locomotion, these environments resemble traversable areas which are shared between multiple agents like humans and robots. The seamless integration of mobile robots into these environments requires accurate predictions of human locomotion. This work considers optimal control and model predictive control approaches for accurate trajectory prediction and proposes to integrate aspects of human behavior to improve their performance. Recently developed models are not able to reproduce accurately trajectories that result from sudden avoidance maneuvers. Particularly, the human locomotion behavior when handling disturbances from other agents poses a problem. The goal of this work is to investigate whether humans alter their trajectory planning horizon, in order to resolve abruptly emerging collision situations. By modeling humans as model predictive controllers, the influence of the planning horizon is investigated in simulations. Based on these results, an experiment is designed to identify, whether humans initiate a change in their locomotion planning behavior while moving in a complex environment. The results support the hypothesis, that humans employ a shorter planning horizon to avoid collisions that are triggered by unexpected disturbances. Observations presented in this work are expected to further improve the generalizability and accuracy of prediction methods based on dynamic models. PMID:27936015

Towards Assessing the Human Trajectory Planning Horizon.

PubMed

Carton, Daniel; Nitsch, Verena; Meinzer, Dominik; Wollherr, Dirk

2016-01-01

Mobile robots are envisioned to cooperate closely with humans and to integrate seamlessly into a shared environment. For locomotion, these environments resemble traversable areas which are shared between multiple agents like humans and robots. The seamless integration of mobile robots into these environments requires accurate predictions of human locomotion. This work considers optimal control and model predictive control approaches for accurate trajectory prediction and proposes to integrate aspects of human behavior to improve their performance. Recently developed models are not able to reproduce accurately trajectories that result from sudden avoidance maneuvers. Particularly, the human locomotion behavior when handling disturbances from other agents poses a problem. The goal of this work is to investigate whether humans alter their trajectory planning horizon, in order to resolve abruptly emerging collision situations. By modeling humans as model predictive controllers, the influence of the planning horizon is investigated in simulations. Based on these results, an experiment is designed to identify, whether humans initiate a change in their locomotion planning behavior while moving in a complex environment. The results support the hypothesis, that humans employ a shorter planning horizon to avoid collisions that are triggered by unexpected disturbances. Observations presented in this work are expected to further improve the generalizability and accuracy of prediction methods based on dynamic models.

Surface Water Sampling Data for BP Spill/Deepwater Horizon

EPA Pesticide Factsheets

The Deepwater Horizon oil spill (also referred to as the BP oil spill) began on 20 April 2010 in the Gulf of Mexico on the BP-operated Macondo Prospect. Following the explosion and sinking of the Deepwater Horizon oil rig, a sea-floor oil gusher flowed for 87 days, until it was capped on 15 July 2010.In response to the BP oil spill, EPA sampled air, water, sediment, and waste generated by the cleanup operations.

NASA's New Horizons Pluto Mission: Continuing Voyager's Legacy o

NASA Image and Video Library

2014-08-25

Dr. John Spencer, senior scientist at the Southwest Research Institute, answers a question from the audience during a panel discussion at the "NASA's New Horizons Pluto Mission: Continuing Voyager's Legacy of Exploration" event on Monday, August, 25, 2014, in the James E. Webb Auditorium at NASA Headquarters in Washington, DC. The panelists gave their accounts of Voyager's encounter with Neptune and discussed their current assignments on NASA's New Horizons mission to Pluto. Photo Credit: (NASA/Joel Kowsky)

33 CFR 147.T08-849 - DEEPWATER HORIZON Mobile Offshore Drilling Unit Safety Zone.

Code of Federal Regulations, 2010 CFR

2010-07-01

... DEEPWATER HORIZON Mobile Offshore Drilling Unit Safety Zone. (a) Location. All areas within 500 meters (1640... area surrounds the DEEPWATER HORIZON, a Mobile Offshore Drilling Unit (MODU), that sank in the... 33 Navigation and Navigable Waters 2 2010-07-01 2010-07-01 false DEEPWATER HORIZON Mobile Offshore...

Horizons of cybernetical physics

PubMed Central

2017-01-01

The subject and main areas of a new research field—cybernetical physics—are discussed. A brief history of cybernetical physics is outlined. The main areas of activity in cybernetical physics are briefly surveyed, such as control of oscillatory and chaotic behaviour, control of resonance and synchronization, control in thermodynamics, control of distributed systems and networks, quantum control. This article is part of the themed issue ‘Horizons of cybernetical physics’. PMID:28115620

NIF featured on BBC "Horizon"

ScienceCinema

Brian Cox

2017-12-09

The National Ignition Facility, the world's largest laser system, located at Lawrence Livermore National Laboratory, was featured in the BBC broadcast "Horizon" hosted by physicist Brian Cox. Here is the NIF portion of the program, which was entitled "Can We Make A Star On Earth?" This video is used with the express permission of the BBC.

NIF featured on BBC "Horizon"

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brian Cox

2010-01-12

The National Ignition Facility, the world's largest laser system, located at Lawrence Livermore National Laboratory, was featured in the BBC broadcast "Horizon" hosted by physicist Brian Cox. Here is the NIF portion of the program, which was entitled "Can We Make A Star On Earth?" This video is used with the express permission of the BBC.

Pre-Hawking radiation cannot prevent the formation of apparent horizon

DOE PAGES

Chen, Pisin; Unruh, William G.; Wu, Chih-Hung; ...

2018-03-30

As an attempt to solve the black hole information loss paradox, recently there has been the suggestion that, due to semiclassical effects, a pre-Hawking radiation must exist during the gravitational collapse of matter, which in turn prevents the apparent horizon from forming. Assuming the pre-Hawking radiation does exist, here we argue the opposite. First we note that the stress energy tensor near the horizon for the pre-Hawking radiation is far too small to do anything to the motion of a collapsing shell. Thus the shell will always cross the apparent horizon within a finite proper time. Moreover, the amount ofmore » energy that can be radiated must be less than half of the total initial energy (if the particle starts at rest at infinity) before the shell becomes a null shell and cannot radiate any more without becoming tachyonic. Here, we conclude that for any gravitational collapsing process within Einstein gravity and semiclassical quantum field theory, the formation of the apparent horizon is inevitable. Pre-Hawking radiation is therefore not a valid solution to the information paradox.« less

Pre-Hawking radiation cannot prevent the formation of apparent horizon

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, Pisin; Unruh, William G.; Wu, Chih-Hung

As an attempt to solve the black hole information loss paradox, recently there has been the suggestion that, due to semiclassical effects, a pre-Hawking radiation must exist during the gravitational collapse of matter, which in turn prevents the apparent horizon from forming. Assuming the pre-Hawking radiation does exist, here we argue the opposite. First we note that the stress energy tensor near the horizon for the pre-Hawking radiation is far too small to do anything to the motion of a collapsing shell. Thus the shell will always cross the apparent horizon within a finite proper time. Moreover, the amount ofmore » energy that can be radiated must be less than half of the total initial energy (if the particle starts at rest at infinity) before the shell becomes a null shell and cannot radiate any more without becoming tachyonic. Here, we conclude that for any gravitational collapsing process within Einstein gravity and semiclassical quantum field theory, the formation of the apparent horizon is inevitable. Pre-Hawking radiation is therefore not a valid solution to the information paradox.« less

Pluto Icy Plains Captured in Highest-Resolution Views from New Horizons

NASA Image and Video Library

2016-01-08

NASA's New Horizons spacecraft continues to transmit the sharpest views of Pluto that it obtained (and recorded) during its flyby of the distant planet on July 14, 2015. The newest image, returned on Dec. 24, 2015, extends New Horizons' highest-resolution swath of Pluto to the very center of the informally named Sputnik Planum, and nearly completes the set of highest-resolution images taken by New Horizons last July. The pictures are part of a sequence taken near New Horizons' closest approach to Pluto, with resolutions of about 250-280 feet (77-85 meters) per pixel -- revealing features smaller than half a city block on Pluto's surface. The images shown here form a strip 50 miles (80 kilometers) wide and more than 400 miles (700 kilometers) long, trending from the northwestern shoreline of Sputnik Planum and out across its icy plains. The images illustrate the polygonal or cellular pattern of the plains, which are thought to result from the convective churning of a deep layer solid, but mobile, nitrogen ice. The surface of Sputnik Planum appears darker toward the shore (at top), possibly implying a change in composition or surface texture. The occasional raised, darker blocks at the cell edges are probably dirty water "icebergs" floating in denser solid nitrogen. The pictures were taken with the telescopic Long Range Reconnaissance Imager (LORRI) aboard New Horizons, from a range of approximately 10,000 miles (17,000 kilometers) over a timespan of about a minute centered on 11:36 UT on July 14 -- just about 15 minutes before New Horizons' closest approach to Pluto. http://photojournal.jpl.nasa.gov/catalog/PIA20336

Digital depth horizon compilations of the Alaskan North Slope and adjacent Arctic regions

USGS Publications Warehouse

Saltus, Richard W.; Bird, Kenneth J.

2003-01-01

Data have been digitized and combined to create four detailed depth horizon grids spanning the Alaskan North Slope and adjacent offshore areas. These map horizon compilations were created to aid in petroleum system modeling and related studies. Topography/bathymetry is extracted from a recent Arctic compilation of global onshore DEM and satellite altimetry and ship soundings offshore. The Lower Cretaceous Unconformity (LCU), the top of the Triassic Shublik Formation, and the pre-Carboniferous acoustic basement horizon grids are created from numerous seismic studies, drill hole information, and interpolation. These horizons were selected because they mark critical times in the geologic evolution of the region as it relates to petroleum. The various horizons clearly show the major tectonic elements of this region including the Brooks Range, Colville Trough, Barrow Arch, Hanna Trough, Chukchi Platform, Nuwuk Basin, Kaktovik Basin, and Canada Basin. The gridded data are available in a variety of data formats for use in regional studies.

NASA's New Horizons Pluto Mission: Continuing Voyager's Legacy o

NASA Image and Video Library

2014-08-25

Dr. David H. Grinspoon, senior scientist at the Planetary Science Institute, speaks about working on NASA's Voyager team while serving as moderator for a panel discussion at the "NASA's New Horizons Pluto Mission: Continuing Voyager's Legacy of Exploration" event on Monday, August, 25, 2014, in the James E. Webb Auditorium at NASA Headquarters in Washington, DC. The panelists gave their accounts of Voyager's encounter with Neptune and discussed their current assignments on NASA's New Horizons mission to Pluto. Photo Credit: (NASA/Joel Kowsky)

New Horizons. A National Workplace Literacy Program. Final Report. "New Horizons" External Evaluation Impact Study.

ERIC Educational Resources Information Center

Hudson, Patt; Gretes, John A.

The New Horizons project was a workplace literacy partnership during which 454 employees (53%) of Georgetown Steel attended classes provided by Horry-Georgetown Technical College in Conway, South Carolina. Of the 454 participants, 294 were white, 159 were black, 71 were female, 383 were male, 133 had been with the company for 5 years or less, and…

Causal nature and dynamics of trapping horizons in black hole collapse

NASA Astrophysics Data System (ADS)

Helou, Alexis; Musco, Ilia; Miller, John C.

2017-07-01

In calculations of gravitational collapse to form black holes, trapping horizons (foliated by marginally trapped surfaces) make their first appearance either within the collapsing matter or where it joins on to a vacuum exterior. Those which then move outwards with respect to the matter have been proposed for use in defining black holes, replacing the global concept of an ‘event horizon’ which has some serious drawbacks for practical applications. We here present results from a study of the properties of both outgoing and ingoing trapping horizons, assuming strict spherical symmetry throughout. We have investigated their causal nature (i.e. whether they are spacelike, timelike or null), making contact with the Misner-Sharp-Hernandez formalism, which has often been used for numerical calculations of spherical collapse. We follow two different approaches, one using a geometrical quantity related to expansions of null geodesic congruences, and the other using the horizon velocity measured with respect to the collapsing matter. After an introduction to these concepts, we then implement them within numerical simulations of stellar collapse, revisiting pioneering calculations from the 1960s where some features of the emergence and subsequent behaviour of trapping horizons could already be seen. Our presentation here is aimed firmly at ‘real world’ applications of interest to astrophysicists and includes the effects of pressure, which may be important for the asymptotic behaviour of the ingoing horizon.

Refraction near the horizon

NASA Technical Reports Server (NTRS)

Schaefer, Bradley E.; Liller, William

1990-01-01

Variations in astronomical refraction near the horizon are examined. Sunset timings, a sextant mounted on a tripod, and a temperature profile are utilized to derive the variations in refraction data, collected from 7 locations. It is determined that the refraction ranges from 0.234 to 1.678 deg with an rms deviation of 0.16, and it is observed that the variation is larger than previously supposed. Some applications for the variation of refraction value are discussed.

Agriculture’s Ethical Horizon, book review

USDA-ARS?s Scientific Manuscript database

Roughly 6.5 billion people inhabit the earth, but over 1 billion people regularly go hungry. This food shortfall poses an ethical dilemma for agriculture, and Agriculture's Ethical Horizon grapples with this dilemma. It argues that agricultural productivity has been the quintessential value of agr...

Near-Optimal Tracking Control of Mobile Robots Via Receding-Horizon Dual Heuristic Programming.

PubMed

Lian, Chuanqiang; Xu, Xin; Chen, Hong; He, Haibo

2016-11-01

Trajectory tracking control of wheeled mobile robots (WMRs) has been an important research topic in control theory and robotics. Although various tracking control methods with stability have been developed for WMRs, it is still difficult to design optimal or near-optimal tracking controller under uncertainties and disturbances. In this paper, a near-optimal tracking control method is presented for WMRs based on receding-horizon dual heuristic programming (RHDHP). In the proposed method, a backstepping kinematic controller is designed to generate desired velocity profiles and the receding horizon strategy is used to decompose the infinite-horizon optimal control problem into a series of finite-horizon optimal control problems. In each horizon, a closed-loop tracking control policy is successively updated using a class of approximate dynamic programming algorithms called finite-horizon dual heuristic programming (DHP). The convergence property of the proposed method is analyzed and it is shown that the tracking control system based on RHDHP is asymptotically stable by using the Lyapunov approach. Simulation results on three tracking control problems demonstrate that the proposed method has improved control performance when compared with conventional model predictive control (MPC) and DHP. It is also illustrated that the proposed method has lower computational burden than conventional MPC, which is very beneficial for real-time tracking control.

Advancing the adverse outcome pathway framework - An international horizon scanning approach (presentation)

EPA Science Inventory

In preparation for a Society of Environmental Toxicology and Chemistry Pellston Workshop titled “Advancing the Adverse Outcome Pathway (AOP) Concept: An International Horizon Scanning Approach,” a horizon scanning effort was undertaken to gather input from the global ...

Factors influencing organic-horizon carbon pools in mixed-species stands of central Maine, USA

Treesearch

Joshua J. Puhlick; Shawn Fraver; Ivan J. Fernandez; Aaron R. Weiskittel; Laura S. Kenefic; Randy Kolka; Marie-Cecile Gruselle

2016-01-01

The overall goal of this study was to evaluate the correlation of multiple abiotic and biotic factors with organic-horizon (O-horizon) carbon (C) content on the Penobscot Experimental Forest in central Maine, USA. O-horizon samples were collected and their associated depths were recorded from stands managed with a range of silvicultural and harvesting treatments (i.e...

Summary and status of the Horizons ephemeris system

NASA Astrophysics Data System (ADS)

Giorgini, J.

2011-10-01

Since 1996, the Horizons system has provided searchable access to JPL ephemerides for all known solar system bodies, several dozen spacecraft, planetary system barycenters, and some libration points. Responding to 18 400 000 requests from 300 000 unique addresses, the system has recently averaged 420 000 ephemeris requests per month. Horizons is accessed and automated using three interfaces: interactive telnet, web-browser form, and e-mail command-file. Asteroid and comet ephemerides are numerically integrated from JPL's database of initial conditions. This small-body database is updated hourly by a separate process as new measurements and discoveries are reported by the Minor Planet Center and automatically incorporated into new JPL orbit solutions. Ephemerides for other objects are derived by interpolating previously developed solutions whose trajectories have been represented in a file. For asteroids and comets, such files may be dynamically created and transferred to users, effectively recording integrator output. These small-body SPK files may then be interpolated by user software to reproduce the trajectory without duplicating the numerically integrated n-body dynamical model or PPN equations of motion. Other Horizons output is numerical and in the form of plain-text observer, vector, osculating element, or close-approach tables, typically expected be read by other software as input. About one hundred quantities can be requested in various time-scales and coordinate systems. For JPL small-body solutions, this includes statistical uncertainties derived from measurement covariance and state transition matrices. With the exception of some natural satellites, Horizons is consistent with DE405/DE406, the IAU 1976 constants, ITRF93, and IAU2009 rotational models.

Geochemical gradients in soil O-horizon samples from southern Norway: Natural or anthropogenic?

USGS Publications Warehouse

Reimann, C.; Englmaier, P.; Flem, B.; Gough, L.; Lamothe, P.; Nordgulen, O.; Smith, D.

2009-01-01

Forty soil O- and C-horizon samples were collected along a south-to-north transect extending inland for approximately 200 km from the southern tip of Norway. The elements As, Au, Bi, Cd, Cu, Ga, Ge, Hf, Hg, In, Mg, Mn, Mo, Na, Ni, Pb, Sb, Se, V, W, Zn and Zr all show a distinct decrease in concentration in soil O-horizons with increasing distance from the coast. The elements showing the strongest coastal enrichment, some by more than an order of magnitude compared to inland samples, are Au, Bi, As, Pb, Sb and Sn. Furthermore, the elements Cd (median O-/median C-horizon = 31), C, Sb, Ag, K, S, Ge (10), Hg, Pb, As, Bi, Sr (5), Se, Au, Ba, Na, Zn, P, Cu and Sn (2) are all strongly enriched in the O-horizon when compared to the underlying C-horizon. Lead isotope ratios, however, do not show any gradient with distance from the coast (declining Pb concentration). Along a 50 km topographically steep east-west transect in the centre of the survey area, far from the coast but crossing several vegetation zones, similar element enrichment patterns and concentration gradients can be observed in the O-horizon. Lead isotope ratios in the O-horizon correlate along both transects with pH and the C/N-ratio, both proxies for the quality of the organic material. Natural conditions in southern Norway, related to climate and vegetation, rather than long range atmospheric transport of air pollutants (LRT), cause the observed features. ?? 2008 Elsevier Ltd.

Horizon scanning for environmental foresight: a review of issues and approaches

Treesearch

David N. Bengston

2013-01-01

Natural resource management organizations carry out a range of activities to examine possible future conditions and trends as part of their planning process, but the distinct approach of formal horizon scanning is often a missing component of strategic thinking and strategy development in these organizations. Horizon scanning is a process for finding and interpreting...

Large storage operations under climate change: expanding uncertainties and evolving tradeoffs

NASA Astrophysics Data System (ADS)

Giuliani, Matteo; Anghileri, Daniela; Castelletti, Andrea; Vu, Phuong Nam; Soncini-Sessa, Rodolfo

2016-03-01

In a changing climate and society, large storage systems can play a key role for securing water, energy, and food, and rebalancing their cross-dependencies. In this letter, we study the role of large storage operations as flexible means of adaptation to climate change. In particular, we explore the impacts of different climate projections for different future time horizons on the multi-purpose operations of the existing system of large dams in the Red River basin (China-Laos-Vietnam). We identify the main vulnerabilities of current system operations, understand the risk of failure across sectors by exploring the evolution of the system tradeoffs, quantify how the uncertainty associated to climate scenarios is expanded by the storage operations, and assess the expected costs if no adaptation is implemented. Results show that, depending on the climate scenario and the time horizon considered, the existing operations are predicted to change on average from -7 to +5% in hydropower production, +35 to +520% in flood damages, and +15 to +160% in water supply deficit. These negative impacts can be partially mitigated by adapting the existing operations to future climate, reducing the loss of hydropower to 5%, potentially saving around 34.4 million US year-1 at the national scale. Since the Red River is paradigmatic of many river basins across south east Asia, where new large dams are under construction or are planned to support fast growing economies, our results can support policy makers in prioritizing responses and adaptation strategies to the changing climate.

Weakly Isolated horizons: first order actions and gauge symmetries

NASA Astrophysics Data System (ADS)

Corichi, Alejandro; Reyes, Juan D.; Vukašinac, Tatjana

2017-04-01

The notion of Isolated Horizons has played an important role in gravitational physics, being useful from the characterization of the endpoint of black hole mergers to (quantum) black hole entropy. With an eye towards a canonical formulation we consider general relativity in terms of connection and vierbein variables and their corresponding first order actions. We focus on two main issues: (i) The role of the internal gauge freedom that exists, in the consistent formulations of the action principle, and (ii) the role that a 3  +  1 canonical decomposition has in the allowed internal gauge freedom. More concretely, we clarify in detail how the requirement of having well posed variational principles compatible with general weakly isolated horizons (WIHs) as internal boundaries does lead to a partial gauge fixing in the first order descriptions used previously in the literature. We consider the standard Hilbert-Palatini action together with the Holst extension (needed for a consistent 3  +  1 decomposition), with and without boundary terms at the horizon. We show in detail that, for the complete configuration space—with no gauge fixing—, while the Palatini action is differentiable without additional surface terms at the inner WIH boundary, the more general Holst action is not. The introduction of a surface term at the horizon—that renders the action for asymptotically flat configurations differentiable—does make the Holst action differentiable, but only if one restricts the configuration space and partially reduces the internal Lorentz gauge. For the second issue at hand, we show that upon performing a 3  +  1 decomposition and imposing the time gauge, there is a further gauge reduction of the Hamiltonian theory in terms of Ashtekar-Barbero variables to a U(1)-gauge theory on the horizon. We also extend our analysis to the more restricted boundary conditions of (strongly) isolated horizons as inner boundary. We show that even when the

Action growth of charged black holes with a single horizon

NASA Astrophysics Data System (ADS)

Cai, Rong-Gen; Sasaki, Misao; Wang, Shao-Jiang

2017-06-01

According to the conjecture "complexity equals action," the complexity of a holographic state is equal to the action of a Wheeler-DeWitt (WDW) patch of black holes in anti-de Sitter space. In this paper we calculate the action growth of charged black holes with a single horizon, paying attention to the contribution from a spacelike singularity inside the horizon. We consider two kinds of such charged black holes: one is a charged dilaton black hole, and the other is a Born-Infeld black hole with β2Q2<1 /4 . In both cases, although an electric charge appears in the black hole solutions, the inner horizon is absent; instead a spacelike singularity appears inside the horizon. We find that the action growth of the WDW patch of the charged black hole is finite and satisfies the Lloyd bound. As a check, we also calculate the action growth of a charged black hole with a phantom Maxwell field. In this case, although the contributions from the bulk integral and the spacelike singularity are individually divergent, these two divergences just cancel each other and a finite action growth is obtained. But in this case, the Lloyd bound is violated as expected.

Anomalous Galactic Dynamics by Collusion of Rindler and Cosmological Horizons

NASA Astrophysics Data System (ADS)

van Putten, Maurice H. P. M.

2017-03-01

In holography, the dimensional reduction of phase space to two dimensions defines a dynamical dark energy of {{Λ }}=(1-q){H}2, associated with the cosmological horizon at a Hubble radius of {R}H=c/H, and inertia m of baryonic matter at acceleration α in terms of a thermodynamic potential U={{mc}}2 of Rindler horizons at ξ ={c}2/α . Here, H is the Hubble parameter with deceleration q and c is the velocity of light. In weak gravity, m drops below Newton’s value m 0 as α < {a}H, when Rindler horizons fall beyond the cosmological horizon. The onset to weak gravity across α ={a}H is sharp by causality. Striking evidence is found in galaxy rotation curves, whose asymptotic dynamics is parameterized by Milgrom’s scale of acceleration {a}0=({cH}/2π )\\sqrt{1-q}. This onset presents a new challenge for canonical dark matter distributions on galactic scales in ΛCDM. Instead, future galaxy surveys may determine {Q}0={{dq}(z)/{dz}| }z=0, to provide a direct test of dynamical dark energy ({Q}0> 2.5) versus ΛCDM ({Q}0< 1) and establish a bound of {10}-30 {{eV}} on the mass of the putative dark matter particle with clustering limited to galaxy clusters.

Black Hole Entropy from Bondi-Metzner-Sachs Symmetry at the Horizon.

PubMed

Carlip, S

2018-03-09

Near the horizon, the obvious symmetries of a black hole spacetime-the horizon-preserving diffeomorphisms-are enhanced to a larger symmetry group with a three-dimensional Bondi-Metzner-Sachs algebra. Using dimensional reduction and covariant phase space techniques, I investigate this augmented symmetry and show that it is strong enough to determine the black hole entropy in any dimension.

Towards thermodynamics of universal horizons in Einstein-æther theory.

PubMed

Berglund, Per; Bhattacharyya, Jishnu; Mattingly, David

2013-02-15

Holography grew out of black hole thermodynamics, which relies on the causal structure and general covariance of general relativity. In Einstein-æther theory, a generally covariant theory with a dynamical timelike unit vector, every solution breaks local Lorentz invariance, thereby grossly modifying the causal structure of gravity. However, there are still absolute causal boundaries, called "universal horizons," which are not Killing horizons yet obey a first law of black hole mechanics and must have an entropy if they do not violate a generalized second law. We couple a scalar field to the timelike vector and show via the tunneling approach that the universal horizon radiates as a blackbody at a fixed temperature, even if the scalar field equations also violate local Lorentz invariance. This suggests that the class of holographic theories may be much broader than currently assumed.

Action at the Horizon: Chandra/EHT Observations of Sgr A*

NASA Astrophysics Data System (ADS)

Neilsen, Joseph

2017-09-01

In April 2017, the Event Horizon Telescope will observe Sgr A* with imaging quality sufficient to resolve the shadow of the black hole, while providing a close-up view of accretion at the horizon. As Sgr A* is a well-known source of X-ray flares, coordinated Chandra/EHT observations offer an incredible opportunity: a chance to observe structures (e.g., hotspots) near the event horizon while tracking their high-energy variability. In anticipation of a follow-up campaign in 2018, we are requesting 4x33 ks Chandra observations of Sgr A* to be coordinated with EHT. This campaign will double our chances of simultaneous flares. We will search for flares and hotspots, provide priors for EHT image reconstruction, and track any activity associated with the closest approach of the massive star S0-2.

Holographic stress-energy tensor near the Cauchy horizon inside a rotating black hole

NASA Astrophysics Data System (ADS)

Ishibashi, Akihiro; Maeda, Kengo; Mefford, Eric

2017-07-01

We investigate a stress-energy tensor for a conformal field theory (CFT) at strong coupling inside a small five-dimensional rotating Myers-Perry black hole with equal angular momenta by using the holographic method. As a gravitational dual, we perturbatively construct a black droplet solution by applying the "derivative expansion" method, generalizing the work of Haddad [Classical Quantum Gravity 29, 245001 (2012), 10.1088/0264-9381/29/24/245001] and analytically compute the holographic stress-energy tensor for our solution. We find that the stress-energy tensor is finite at both the future and past outer (event) horizons and that the energy density is negative just outside the event horizons due to the Hawking effect. Furthermore, we apply the holographic method to the question of quantum instability of the Cauchy horizon since, by construction, our black droplet solution also admits a Cauchy horizon inside. We analytically show that the null-null component of the holographic stress-energy tensor negatively diverges at the Cauchy horizon, suggesting that a singularity appears there, in favor of strong cosmic censorship.

Quantum Tunneling from Apparent Horizon of Rainbow-FRW Universe

NASA Astrophysics Data System (ADS)

Lin, Kai; Yang, Shuzheng

2009-07-01

The quantum tunneling from the apparent horizon of rainbow-FRW universe is studied in this paper. We apply the semi-classical approximation, which is put forward by Parikh and Wilczek et al., to research on the scalar field particles tunneling from the apparent horizon of the rainbow-FRW universe, and then use the spin 1/2 Fermions tunneling theory, which brought forward by Kerner and Mann firstly, to research on the Fermions Hawking radiation via semi-classical approximation. Finally, we discuss the meanings of the quantum effect via Finsler geometry.

A horizon scan of global conservation issues for 2014

PubMed Central

Sutherland, William J.; Aveling, Rosalind; Brooks, Thomas M.; Clout, Mick; Dicks, Lynn V.; Fellman, Liz; Fleishman, Erica; Gibbons, David W.; Keim, Brandon; Lickorish, Fiona; Monk, Kathryn A.; Mortimer, Diana; Peck, Lloyd S.; Pretty, Jules; Rockström, Johan; Rodríguez, Jon Paul; Smith, Rebecca K.; Spalding, Mark D.; Tonneijck, Femke H.; Watkinson, Andrew R.

2014-01-01

This paper presents the output of our fifth annual horizon-scanning exercise, which aims to identify topics that increasingly may affect conservation of biological diversity, but have yet to be widely considered. A team of professional horizon scanners, researchers, practitioners, and a journalist identified 15 topics which were identified via an iterative, Delphi-like process. The 15 topics include a carbon market induced financial crash, rapid geographic expansion of macroalgal cultivation, genetic control of invasive species, probiotic therapy for amphibians, and an emerging snake fungal disease. PMID:24332318

A horizon scan of global conservation issues for 2015.

PubMed

Sutherland, William J; Clout, Mick; Depledge, Michael; Dicks, Lynn V; Dinsdale, Jason; Entwistle, Abigail C; Fleishman, Erica; Gibbons, David W; Keim, Brandon; Lickorish, Fiona A; Monk, Kathryn A; Ockendon, Nancy; Peck, Lloyd S; Pretty, Jules; Rockström, Johan; Spalding, Mark D; Tonneijck, Femke H; Wintle, Bonnie C

2015-01-01

This paper presents the results of our sixth annual horizon scan, which aims to identify phenomena that may have substantial effects on the global environment, but are not widely known or well understood. A group of professional horizon scanners, researchers, practitioners, and a journalist identified 15 topics via an iterative, Delphi-like process. The topics include a novel class of insecticide compounds, legalisation of recreational drugs, and the emergence of a new ecosystem associated with ice retreat in the Antarctic. Copyright © 2014 Elsevier Ltd. All rights reserved.

75 FR 65309 - National Commission on the BP Deepwater Horizon Oil Spill and Offshore Drilling

Federal Register 2010, 2011, 2012, 2013, 2014

2010-10-22

... DEPARTMENT OF ENERGY National Commission on the BP Deepwater Horizon Oil Spill and Offshore...: This notice announces an open meeting of the National Commission on the BP Deepwater Horizon Oil Spill... concerning the root cause of the BP Deepwater Horizon explosion, fire, and oil spill and to develop options...

75 FR 37783 - National Commission on the BP Deepwater Horizon Oil Spill and Offshore Drilling

Federal Register 2010, 2011, 2012, 2013, 2014

2010-06-30

... DEPARTMENT OF ENERGY National Commission on the BP Deepwater Horizon Oil Spill and Offshore...: This notice announces an open meeting of the National Commission on the BP Deepwater Horizon Oil Spill... Horizon explosion, fire and oil spill and develop options to guard against, and mitigate the impact of...

75 FR 60097 - National Commission on the BP Deepwater Horizon Oil Spill and Offshore Drilling

Federal Register 2010, 2011, 2012, 2013, 2014

2010-09-29

... DEPARTMENT OF ENERGY National Commission on the BP Deepwater Horizon Oil Spill and Offshore...: This notice announces an open meeting of the National Commission on the BP Deepwater Horizon Oil Spill... cause of the BP Deepwater Horizon explosion, fire, and oil spill and to develop options to guard against...

75 FR 69652 - National Commission on the BP Deepwater Horizon Oil Spill and Offshore Drilling

Federal Register 2010, 2011, 2012, 2013, 2014

2010-11-15

... DEPARTMENT OF ENERGY National Commission on the BP Deepwater Horizon Oil Spill and Offshore...: This notice announces an open meeting of the National Commission on the BP Deepwater Horizon Oil Spill... cause of the BP Deepwater Horizon explosion, fire, and oil spill and to develop options to guard against...

In Charon's Shadow: Analysis of the UV Solar Occultation from New Horizons

NASA Astrophysics Data System (ADS)

Kammer, Joshua A.; Stern, S. A.; Weaver, H. A.; Young, L. A.; Ennico, K. A.; Olkin, C. B.; Gladstone, G. R.; Summers, M. E.; Greathouse, T. K.; Retherford, K. D.; Versteeg, M. H.; Parker, J. W.; Steffl, A. J.; Schindhelm, E.; Strobel, D. F.; Linscott, I. R.; Hinson, D. P.; Tyler, G. L.; Woods, W. W.

2015-11-01

Observations of Charon, Pluto's largest moon, have so far yielded no evidence for a substantial atmosphere. However, during the flyby of New Horizons through the Pluto-Charon system, the Alice ultraviolet spectrograph successfully acquired the most sensitive measurements to date during an occultation of the sun as New Horizons passed through Charon's shadow. These observations include wavelength coverage in the extreme- and far-ultraviolet (EUV and FUV) from 52 nm to 187 nm. We will present these results from Alice, and discuss their implications for an atmosphere on Charon.This work was supported by NASA's New Horizons project.

Triggering effect of mining at different horizons in the rock mass with excavations. Mathematical modeling

NASA Astrophysics Data System (ADS)

Eremin, M. O.; Makarov, P. V.

2017-12-01

On the basis of a quite simple structural model of rock mass, containing coal seams on two horizons, coal mining is numerically modeled. A finite difference numerical technique is applied. At first, mining starts at the upper horizon and then moves to the lower horizon. It is shown that a mining process at the lower horizon has a significant triggering influence on the growth of damage zones in the roof and floor at the upper horizon. The features of spatiotemporal migration of deformation activity are studied numerically. Foci of large-scale fracture are located at the boundary of the seismic silence zone and the zone where the deformation activity migrates. This boundary has an additional characteristic: the maximum gradient of rock pressure is observed in this zone.

Gateway's Horizon: A Center of Excellence

ERIC Educational Resources Information Center

Herring, Jayne; Colony, Lee

2007-01-01

This article describes Gateway Technical College's Horizon Center for Transportation Technology, located in Kenosha, Wisconsin, which was the product of collaboration with business and industry, community support and a U.S. Department of Labor (DOL) grant. The center, which opened this fall, is a prime example of a sustainable community…

New Concepts on the Educational Horizon.

ERIC Educational Resources Information Center

Gilchrist, Robert S.; Mitchell, Edna

Four dimensions in education provide a basis for discussing future horizons: (1) curriculum development, (2) teacher education, (3) administration and organization, and (4) research and development. These areas are interdependent, and one cannot be improved or changed without affecting the other areas. Within these areas, some of the broad changes…

Deepwater Horizon Oil Spill: Five Years Later | NOAA Gulf Spill Restoration

Science.gov Websites

Archive Home Deepwater Horizon Oil Spill: Five Years Later Deepwater Horizon Oil Spill: Five Years Later oil leak from the well. Before it was capped three months later, more than 100 million gallons of oil spilled into the Gulf-resulting in the largest offshore oil spill in U.S. history. The Trustees

Medical Information & Technology: Rapidly Expanding Vast Horizons

NASA Astrophysics Data System (ADS)

Sahni, Anil K.

2012-12-01

During ÑMedical Council Of India?, Platinum Jubilee Year (1933-2008) Celebrations, In Year 2008, Several Scientific Meeting/Seminar/Symposium, On Various Topics Of Contemporary Importance And Relevance In The Field Of ÑMedical Education And Ethics?, Were Organized, By Different Medical Colleges At Various Local, State, National Levels. The Present Discussion, Is An Comprehensive Summary Of Various Different Aspects of ìMedical Information Communication Technologyî, Especially UseFul For The Audience Stratum Group Of Those Amateur Medical & Paramedical Staff, With No Previous Work Experience Knowledge Of Computronics Applications. Outlining The, i.Administration Applications: Medical Records Etc, ii. Clinical Applications: Pros pective Scope Of TeleMedicine Applicabilities Etc iii. Other Applications: Efforts To Augment Improvement Of Medical Education, Medical Presentations, Medical Education And Research Etc. ÑMedical Trancription? & Related Recent Study Fields e.g ÑModern Pharmaceuticals?,ÑBio-Engineering?, ÑBio-Mechanics?, ÑBio-Technology? Etc., Along With Important Aspects Of Computers-General Considerations, Computer Ergonomics Assembled To Summarize, The AwareNess Regarding Basic Fundamentals Of Medical Computronics & Its Practically SuccessFul Utilities.

Expanding Horizons--Into the Future with Confidence!

ERIC Educational Resources Information Center

Volk, Valerie

2006-01-01

Gifted students often show a deep interest in and profound concern for the complex issues of society. Given the leadership potential of these students and their likely responsibility for solving future social problems, they need to develop this awareness and also a sense of confidence in dealing with future issues. The Future Problem Solving…

Near-horizon BMS symmetries as fluid symmetries

NASA Astrophysics Data System (ADS)

Penna, Robert F.

2017-10-01

The Bondi-van der Burg-Metzner-Sachs (BMS) group is the asymptotic symmetry group of asymptotically flat gravity. Recently, Donnay et al. have derived an analogous symmetry group acting on black hole event horizons. For a certain choice of boundary conditions, it is a semidirect product of Diff( S 2), the smooth diffeomorphisms of the twosphere, acting on C ∞( S 2), the smooth functions on the two-sphere. We observe that the same group appears in fluid dynamics as symmetries of the compressible Euler equations. We relate these two realizations of Diff( S 2) ⋉ C ∞( S 2) using the black hole membrane paradigm. We show that the Lie-Poisson brackets of membrane paradigm fluid charges reproduce the near-horizon BMS algebra. The perspective presented here may be useful for understanding the BMS algebra at null infinity.

Horizon sensors attitude errors simulation for the Brazilian Remote Sensing Satellite

NASA Astrophysics Data System (ADS)

Vicente de Brum, Antonio Gil; Ricci, Mario Cesar

Remote sensing, meteorological and other types of satellites require an increasingly better Earth related positioning. From the past experience it is well known that the thermal horizon in the 15 micrometer band provides conditions of determining the local vertical at any time. This detection is done by horizon sensors which are accurate instruments for Earth referred attitude sensing and control whose performance is limited by systematic and random errors amounting about 0.5 deg. Using the computer programs OBLATE, SEASON, ELECTRO and MISALIGN, developed at INPE to simulate four distinct facets of conical scanning horizon sensors, attitude errors are obtained for the Brazilian Remote Sensing Satellite (the first one, SSR-1, is scheduled to fly in 1996). These errors are due to the oblate shape of the Earth, seasonal and latitudinal variations of the 15 micrometer infrared radiation, electronic processing time delay and misalignment of sensor axis. The sensor related attitude errors are thus properly quantified in this work and will, together with other systematic errors (for instance, ambient temperature variation) take part in the pre-launch analysis of the Brazilian Remote Sensing Satellite, with respect to the horizon sensor performance.

Senior Adult Bands: Music's New Horizon.

ERIC Educational Resources Information Center

Coffman, Don D.; Levy, Katherine M.

1997-01-01

Discusses the success of Iowa City's (Iowa) New Horizons Band that consists of 55 senior adult beginners and former instrumentalists. Describes the organization of the band program, the senior's performance skills and commitment, and the ongoing challenges. Gives a selected listing of the music the band plays at concerts and other events. (CMK)

Forecast horizon of multi-item dynamic lot size model with perishable inventory.

PubMed

Jing, Fuying; Lan, Zirui

2017-01-01

This paper studies a multi-item dynamic lot size problem for perishable products where stock deterioration rates and inventory costs are age-dependent. We explore structural properties in an optimal solution under two cost structures and develop a dynamic programming algorithm to solve the problem in polynomial time when the number of products is fixed. We establish forecast horizon results that can help the operation manager to decide the precise forecast horizon in a rolling decision-making process. Finally, based on a detailed test bed of instance, we obtain useful managerial insights on the impact of deterioration rate and lifetime of products on the length of forecast horizon.

Forecast horizon of multi-item dynamic lot size model with perishable inventory

PubMed Central

Jing, Fuying

2017-01-01

This paper studies a multi-item dynamic lot size problem for perishable products where stock deterioration rates and inventory costs are age-dependent. We explore structural properties in an optimal solution under two cost structures and develop a dynamic programming algorithm to solve the problem in polynomial time when the number of products is fixed. We establish forecast horizon results that can help the operation manager to decide the precise forecast horizon in a rolling decision-making process. Finally, based on a detailed test bed of instance, we obtain useful managerial insights on the impact of deterioration rate and lifetime of products on the length of forecast horizon. PMID:29125856

Apparent violation of the principle of equivalence and killing horizons. [for relativity

NASA Technical Reports Server (NTRS)

Zimmerman, R. L.; Farhoosh, H.

1980-01-01

By means of the principle of equivalence the qualitative behavior of the Schwarzschild horizon about a uniformly accelerating particle was deduced. This result is confirmed for an exact solution of a uniformly accelerating object in the limit of small accelerations. For large accelerations the Schwarzschild horizon appears to violate the qualitative behavior established via the principle of equivalence. When similar arguments are extended to an observable such as the red shift between two observers, there is no departure from the results expected from the principle of equivalence. The resolution of the paradox is brought about by a compensating effect due to the Rindler horizon.

Soil organic matter in podzol horizons of the Amazon region: Humification, recalcitrance, and dating.

PubMed

Tadini, Amanda M; Nicolodelli, Gustavo; Senesi, Giorgio S; Ishida, Débora A; Montes, Célia R; Lucas, Yves; Mounier, Stéphane; Guimarães, Francisco E G; Milori, Débora M B P

2018-02-01

Characteristics of soil organic matter (SOM) are important, especially in the Amazon region, which represents one of the world's most relevant carbon reservoirs. In this work, the concentrations of carbon and differences in its composition (humification indexes) were evaluated and compared for several horizons (0 to 390cm) of three typical Amazonian podzol profiles. Fluorescence spectroscopy was used to investigate the humic acid (HA) fractions of SOM isolated from the different samples. Simple and labile carbon structures appeared to be accumulated in surface horizons, while more complex humified compounds were leached and accumulated in intermediate and deeper Bh horizons. The results suggested that the humic acids originated from lignin and its derivatives, and that lignin could accumulate in some Bh horizons. The HA present in deeper Bh horizons appeared to originate from different formation pathways, since these horizons showed different compositions. There were significant compositional changes of HA with depth, with four types of organic matter: recalcitrant, humified, and old dating; labile and young dating; humified and young dating; and little humified and old dating. Therefore, the humification process had no direct relation with the age of the organic matter in the Amazonian podzols. Copyright © 2017 Elsevier B.V. All rights reserved.

Event Horizon Telescope observations as probes for quantum structure of astrophysical black holes

NASA Astrophysics Data System (ADS)

Giddings, Steven B.; Psaltis, Dimitrios

2018-04-01

The need for a consistent quantum evolution for black holes has led to proposals that their semiclassical description is modified not just near the singularity, but at horizon or larger scales. If such modifications extend beyond the horizon, they influence regions accessible to distant observation. Natural candidates for these modifications behave like metric fluctuations, with characteristic length scales and timescales set by the horizon radius. We investigate the possibility of using the Event Horizon Telescope to observe these effects, if they have a strength sufficient to make quantum evolution consistent with unitarity, without introducing new scales. We find that such quantum fluctuations can introduce a strong time dependence for the shape and size of the shadow that a black hole casts on its surrounding emission. For the black hole in the center of the Milky Way, detecting the rapid time variability of its shadow will require nonimaging timing techniques. However, for the much larger black hole in the center of the M87 galaxy, a variable black-hole shadow, if present with these parameters, would be readily observable in the individual snapshots that will be obtained by the Event Horizon Telescope.

NASA's New Horizons Pluto Mission: Continuing Voyager's Legacy o

NASA Image and Video Library

2014-08-25

Dr. John Spencer, senior scientist at the Southwest Research Institute, left, Dr. Jeffrey Moore, senior scientist at NASA Ames Researh Center, center, and Dr. David H. Grinspoon, senior scientist at the Plentary Science Institute, left, are seen during a panel discussion at the "NASA's New Horizons Pluto Mission: Continuing Voyager's Legacy of Exploration" event on Monday, August, 25, 2014, in the James E. Webb Auditorium at NASA Headquarters in Washington, DC. The panelists gave their accounts of Voyager's encounter with Neptune and discussed their current assignments on NASA's New Horizons mission to Pluto. Photo Credit: (NASA/Joel Kowsky)

New Horizons at Pluto

NASA Technical Reports Server (NTRS)

2007-01-01

Artist's concept of the New Horizons spacecraft as it approaches Pluto and its largest moon, Charon, in July 2015. The craft's miniature cameras, radio science experiment, ultraviolet and infrared spectrometers and space plasma experiments will characterize the global geology and geomorphology of Pluto and Charon, map their surface compositions and temperatures, and examine Pluto's atmosphere in detail. The spacecraft's most prominent design feature is a nearly 7-foot (2.1-meter) dish antenna, through which it will communicate with Earth from as far as 4.7 billion miles (7.5 billion kilometers) away.

Violations of the equivalence principle by a nonlocally reconstructed vacuum at the black hole horizon.

PubMed

Bousso, Raphael

2014-01-31

If information escapes from an evaporating black hole, then field modes just outside the horizon must be thermally entangled with distant Hawking radiation. But for an infalling observer to find empty space at the horizon, the same modes would have to be entangled with the black hole interior. Thus, unitarity appears to require a "firewall" at the horizon. Identifying the interior with the distant radiation promises to resolve the entanglement conflict and restore the vacuum. But the map must adjust for any interactions, or else the firewall will reappear if the Hawking radiation scatters off the cosmic microwave background. Such a map produces a "frozen vacuum," a phenomenon that is arguably worse than a firewall. An infalling observer is unable to excite the vacuum near the horizon. This allows the horizon to be locally detected and so violates the equivalence principle.

Lithological Properties of Inception Horizons - The key to understand cave development along bedding planes

NASA Astrophysics Data System (ADS)

Filipponi, M.; Jeannin, P.-Y.

2009-04-01

Recent studies on the complex 3D geometry of large cave systems around the World allowed us to get statistical evidence of the inception horizon hypothesis. It clearly confirmed the idea that the development of karst conduits under phreatic conditions is strongly related to a restricted number of so-called inception horizons. An inception horizon is a part of a rock succession that favours the earliest cave forming processes. However some main question remains: What makes one specific stratigraphical horizon favourable to karstification? What kinds of processes are involved and which of them are the most important? Furthermore is it possible to recognize an inception horizon by some lithological properties? In order to understand the reason(s) why a specific stratigraphical horizon is used for cave development we sampled 18 inception horizons of six cave systems as well as the surrounding rock mass. More than 200 rock micro-cores have been drilled and analysed to determine parameters controlling the speleogenesis. The analysis of these cores gives a first idea of the different key properties of inception horizons. From a theoretical point of view it can be expected that during the process of karst development the significance the property/ies will change, because they have been consumed or the associated speleogenetical processes become subordinated to others. Therefore we suggest using an approached named the "speleogenetic scale of influence". The idea is to consider the increase of porosity produced by the speleogenetic processes associated to one specific property. For example, the scale of influence of a pyrite crystal is determined by the dissolution capacity of the sulphuric acid produced by the weathering process of this crystal (i.e. around 6 time the volume of the crystal). This means that the influence of the pyrite can be assumed to be potentially relevant as long as the size of the pores is smaller than around 6 times the average volume of the pyrite

Effectiveness and Cost-Effectiveness of Expanded Antiviral Prophylaxis and Adjuvanted Vaccination Strategies for the Next Influenza Pandemic

PubMed Central

Khazeni, Nayer; Hutton, David W; Garber, Alan M; Owens, Douglas K

2011-01-01

Background The pandemic potential of the influenza A (H5N1) virus is among the greatest public health concerns of the 21st century. Objective To determine the effectiveness and cost-effectiveness of alternative pandemic mitigation and response strategies. Design Compartmental epidemic model in conjunction with a Markov model of disease progression. Data Sources Literature and expert opinion. Target Population Residents of a U.S. metropolitan city. Time Horizon Lifetime. Perspective Societal. Interventions One mitigation strategy used non-pharmaceutical interventions, vaccination, and antiviral pharmacotherapy in quantities similar to those available currently in the U.S. stockpile. The second and third strategies used expanded supplies of either antivirals (expanded antiviral prophylaxis strategy) or adjuvanted vaccine (expanded vaccination strategy) in addition to non-pharmaceutical interventions. Outcome Measures Infections and deaths averted, costs, quality-adjusted life-years (QALYs), and incremental cost-effectiveness. Results of Base Case Analysis The stockpiled strategy averted 44% of infections and deaths, gaining 258,342 QALYs at $8,907 per QALY gained relative to no intervention. Expanded antiviral prophylaxis delayed the pandemic, averting 48% of infections and deaths, and gaining 282,329 QALYs, with a less favorable cost-effectiveness ratio than adjuvanted vaccination. Adjuvanted vaccination was the most effective strategy and was cost-effective, averting 68% of infections and deaths, and gaining 404,030 QALYs at $10,844 per QALY gained relative to stockpiled strategy. Results of Sensitivity Analysis Over a wide range of assumptions, the incremental cost-effectiveness ratio of the expanded adjuvanted vaccination strategy was less than $50,000 per QALY gained. Limitations Large groups and frequent contacts may spread the virus more rapidly. The model is not designed to target interventions to specific groups. Conclusions Expanded adjuvanted vaccination

Cool horizons lead to information loss

NASA Astrophysics Data System (ADS)

Chowdhury, Borun D.

2013-10-01

There are two evidences for information loss during black hole evaporation: (i) a pure state evolves to a mixed state and (ii) the map from the initial state to final state is non-invertible. Any proposed resolution of the information paradox must address both these issues. The firewall argument focuses only on the first and this leads to order one deviations from the Unruh vacuum for maximally entangled black holes. The nature of the argument does not extend to black holes in pure states. It was shown by Avery, Puhm and the author that requiring the initial state to final state map to be invertible mandates structure at the horizon even for pure states. The proof works if black holes can be formed in generic states and in this paper we show that this is indeed the case. We also demonstrate how models proposed by Susskind, Papadodimas et al. and Maldacena et al. end up making the initial to final state map non-invertible and thus make the horizon "cool" at the cost of unitarity.

All Clear for New Horizons

NASA Image and Video Library

2015-07-01

This illustration shows some of the final images used to determine that the coast is clear for New Horizons' flight through the Pluto system. These images show the difference between two sets of 48 combined 10-second exposures with New Horizons Long Range Reconnaissance Imager (LORRI) camera, taken at 8:40 UTC and 10:25 UTC on June 26, 2015, from a range of 21.5 million kilometers (approximately 13 million miles) to Pluto. The known small moons, Nix, Hydra, Kerberos and Styx, are visible as adjacent bright and dark pairs of dots, due to their motion in the 105 minutes between the two image sets. The images have been extensively processed to remove the glare and "ghosts" (i.e., lens flare) from Pluto and Charon, and also to remove background stars, though many of the brighter stars are imperfectly removed and appear as irregular bright and dark blobs. These and other similar sets of images demonstrate that there are no previously unknown moons brighter than 15 times fainter than Styx (the faintest known moon) in the region outside of Charon's orbit, or brighter than five times fainter than Styx in the region between Charon's orbit and a few thousand kilometers above Pluto's surface. http://photojournal.jpl.nasa.gov/catalog/PIA19695

Time Horizon and Social Scale in Communication

NASA Astrophysics Data System (ADS)

Krantz, D. H.

2010-12-01

In 2009 our center (CRED) published a first version of The Psychology of Climate Change Communication. In it, we attempted to summarize facts and concepts from psychological research that could help guide communication. While this work focused on climate change, most of the ideas are at least partly applicable for communication about a variety of natural hazards. Of the many examples in this guide, I mention three. Single-action bias is the human tendency to stop considering further actions that might be needed to deal with a given hazard, once a single action has been taken. Another example is the importance of group affiliation in motivating voluntary contributions to joint action. A third concerns the finding that group participation enhances understanding of probabilistic concepts and promotes action in the face of uncertainty. One current research direction, which goes beyond those included in the above publication, focuses on how time horizons arise in the thinking of individuals and groups, and how these time horizons might influence hazard preparedness. On the one hand, individuals sometimes appear impatient, organizations look for immediate results, and officials fail to look beyond the next election cycle. Yet under some laboratory conditions and in some subcultures, a longer time horizon is adopted. We are interested in how time horizon is influenced by group identity and by the very architecture of planning and decision making. Institutional changes, involving long-term contractual relationships among communities, developers, insurers, and governments, could greatly increase resilience in the face of natural hazards. Communication about hazards, in the context of such long-term contractual relationships might look very different from communication that is first initiated by immediate threat. Another new direction concerns the social scale of institutions and of communication about hazards. Traditionally, insurance contracts share risk among a large

New perspectives for European climate services: HORIZON2020

NASA Astrophysics Data System (ADS)

Bruning, Claus; Tilche, Andrea

2014-05-01

The developing of new end-to-end climate services was one of the core priorities of 7th Framework for Research and Technological Development of the European Commission and will become one of the key strategic priorities of Societal Challenge 5 of HORIZON2020 (the new EU Framework Programme for Research and Innovation 2014-2020). Results should increase the competitiveness of European businesses, and the ability of regional and national authorities to make effective decisions in climate-sensitive sectors. In parallel, the production of new tailored climate information should strengthen the resilience of the European society to climate change. In this perspective the strategy to support and foster the underpinning science for climate services in HORIZON2020 will be presented.

Rogue events in the group velocity horizon.

PubMed

Demircan, Ayhan; Amiranashvili, Shalva; Brée, Carsten; Mahnke, Christoph; Mitschke, Fedor; Steinmeyer, Günter

2012-01-01

The concept of rogue waves arises from a mysterious and potentially calamitous phenomenon of oceanic surfaces. There is mounting evidence that they are actually commonplace in a variety of different physical settings. A set of defining criteria has been advanced; this set is of great generality and therefore applicable to a wide class of systems. The question arises naturally whether there are generic mechanisms responsible for extreme events in different systems. Here we argue that under suitable circumstances nonlinear interaction between weak and strong waves results in intermittent giant waves with all the signatures of rogue waves. To obtain these circumstances only a few basic conditions must be met. Then reflection of waves at the so-called group-velocity horizon occurs. The connection between rogue waves and event horizons, seemingly unrelated physical phenomena, is identified as a feature common in many different physical systems.

Rogue events in the group velocity horizon

PubMed Central

Demircan, Ayhan; Amiranashvili, Shalva; Brée, Carsten; Mahnke, Christoph; Mitschke, Fedor; Steinmeyer, Günter

2012-01-01

The concept of rogue waves arises from a mysterious and potentially calamitous phenomenon of oceanic surfaces. There is mounting evidence that they are actually commonplace in a variety of different physical settings. A set of defining criteria has been advanced; this set is of great generality and therefore applicable to a wide class of systems. The question arises naturally whether there are generic mechanisms responsible for extreme events in different systems. Here we argue that under suitable circumstances nonlinear interaction between weak and strong waves results in intermittent giant waves with all the signatures of rogue waves. To obtain these circumstances only a few basic conditions must be met. Then reflection of waves at the so-called group-velocity horizon occurs. The connection between rogue waves and event horizons, seemingly unrelated physical phenomena, is identified as a feature common in many different physical systems. PMID:23152941

Horizon nomenclature for quartzipsamments in the Carolina and Georgia Sand Hills, South Carolina

USDA-ARS?s Scientific Manuscript database

Quartzipsamments comprise about 189,600 hectare (9.5 percent) of the Carolina and Georgia Sand Hills region (MLRA 137). Official Series Descriptions typically have A - C (Lakeland Series; Typic subgroup) or A - E - E and Bt (Alpin Series; Lamellic subgroup) horizon designation. Horizon colors, alon...

Infrared horizon sensor modeling for attitude determination and control - Analysis and mission experience

NASA Technical Reports Server (NTRS)

Singhal, S. P.; Phenneger, M. C.; Stengle, T. H.

1986-01-01

This paper summarizes the work of the Flight Dynamics Division of the National Aeronautics and Space Administration/Goddard Space Flight Center in analyzing and evaluating the performance of a variety of infrared horizon sensors on 12 spaceflight missions from 1973 to 1984. Earth infrared radiance modeling, using the LOWTRAN 5 Program, and the Horizon Radiance Modeling Utility are also described. Mission data are presented for Magsat and the Earth Radiation Budget Satellite, with analysis to assess the sensor modeling as well as cloud and sun interference effects. Recommendations are made regarding future directions for the infrared horizon technology.

A three-degree horizon of peace in the military alliance network

PubMed Central

Li, Weihua; Bradshaw, Aisha E.; Clary, Caitlin B.; Cranmer, Skyler J.

2017-01-01

States form defensive military alliances to enhance their security in the face of potential or realized interstate conflict. The network of these international alliances is increasingly interconnected, now linking most of the states in a complex web of ties. These alliances can be used both as a tool for securing cooperation and to foster peace between direct partners. However, do indirect connections—such as the ally of an ally or even further out in the alliance network—result in lower probabilities of conflict? We investigate the extent to which military alliances produce peace between states that are not directly allied. We find that the peacemaking horizon of indirect alliances extends through the network up to three degrees of separation. Within this horizon of influence, a lack of decay in the effect of degrees of distance indicates that alliances do not diminish with respect to their ability to affect peace regardless of whether or not the states in question are directly allied. Beyond the three-degree horizon of influence, we observe a sharp decline in the effect of indirect alliances on bilateral peace. Further investigation reveals that the community structure of the alliance network plays a role in establishing this horizon, but the effects of indirect alliances are not spurious to the community structure. PMID:28275732

Lithology and paleontology of the reflective layer horizon a.

PubMed

Saito, T; Burckle, L H; Ewing, M

1966-12-02

Cores recovered from horizon A are Late Cretaceous (Maestrichtian) in age and consist o alternating layers of calcareous turbidites and "red clay." The presence of red clay suggests that the water depth in this area during Cretaceous time was at least as great as at present-more than 5100 meters. A middle Cretaceous (Cenomanian) core consisting of interbedded sand and gravel and light-to-dark-gray lutite was taken in the same area from a layer stratigraphically below the horizon; the presence of hydrogen sulfide and iron sulfide may indicate anaerobic conditions that may be attributable to local ponding of sediment in Cenomanian time.

A Horizon Scan of Global Conservation Issues for 2016.

PubMed

Sutherland, William J; Broad, Steven; Caine, Jacqueline; Clout, Mick; Dicks, Lynn V; Doran, Helen; Entwistle, Abigail C; Fleishman, Erica; Gibbons, David W; Keim, Brandon; LeAnstey, Becky; Lickorish, Fiona A; Markillie, Paul; Monk, Kathryn A; Mortimer, Diana; Ockendon, Nancy; Pearce-Higgins, James W; Peck, Lloyd S; Pretty, Jules; Rockström, Johan; Spalding, Mark D; Tonneijck, Femke H; Wintle, Bonnie C; Wright, Katherine E

2016-01-01

This paper presents the results of our seventh annual horizon scan, in which we aimed to identify issues that could have substantial effects on global biological diversity in the future, but are not currently widely well known or understood within the conservation community. Fifteen issues were identified by a team that included researchers, practitioners, professional horizon scanners, and journalists. The topics include use of managed bees as transporters of biological control agents, artificial superintelligence, electric pulse trawling, testosterone in the aquatic environment, building artificial oceanic islands, and the incorporation of ecological civilization principles into government policies in China. Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.

Numerical Tests of the Cosmic Censorship Conjecture via Event-Horizon Finding

NASA Astrophysics Data System (ADS)

Okounkova, Maria; Ott, Christian; Scheel, Mark; Szilagyi, Bela

2015-04-01

We present the current state of our research on the possibility of naked singularity formation in gravitational collapse, numerically testing both the cosmic censorship conjecture and the hoop conjecture. The former of these posits that all singularities lie behind an event horizon, while the later conjectures that this is true if collapse occurs from an initial configuration with all circumferences C <= 4 πM . We reconsider the classical Shapiro & Teukolsky (1991) prolate spheroid naked singularity scenario. Using the exponentially error-convergent Spectral Einstein Code (SpEC) we simulate the collapse of collisionless matter and probe for apparent horizons. We propose a new method to probe for the existence of an event horizon by following characteristic from regions near the singularity, using methods commonly employed in Cauchy characteristic extraction. This research was partially supported by NSF under Award No. PHY-1404569.

Scalar hairy black holes and scalarons in the isolated horizons formalism

DOE Office of Scientific and Technical Information (OSTI.GOV)

Corichi, Alejandro; Instituto de Matematicas, Universidad Nacional Autonoma de Mexico, A. Postal 61-3, Morelia, Michoacan, 58090; Nucamendi, Ulises

The Isolated Horizons (IH) formalism, together with a simple phenomenological model for colored black holes has been used to predict nontrivial formulas that relate the ADM mass of the solitons and hairy Black Holes of Gravity-Matter system on the one hand, and several horizon properties of the black holes in the other. In this article, the IH formalism is tested numerically for spherically symmetric solutions to an Einstein-Higgs system where hairy black holes were recently found to exist. It is shown that the mass formulas still hold and that, by appropriately extending the current model, one can account for themore » behavior of the horizon properties of these new solutions. An empirical formula that approximates the ADM mass of hairy solutions is put forward, and some of its properties are analyzed.« less

New Horizons Best Close-Up of Pluto Surface

NASA Image and Video Library

2016-05-27

This frame from a movie, which extends across the hemisphere that faced New Horizons spacecraft as it flew past Pluto on July 14, 2015, includes all of the highest-resolution images taken by the NASA probe. With a resolution of about 260 feet (80 meters) per pixel, the movie affords New Horizons scientists and the public the best opportunity to examine the fine details of the various types of terrain the mosaic covers, and determine the processes that formed and shaped them. The view extends from the "limb" of Pluto at the top of the strip, almost to the "terminator" (or day/night line) in the southeast of the encounter hemisphere, seen at the bottom of the strip. The width of the strip ranges from more than 55 miles (90 kilometers) at its northern end to about 45 miles (75 kilometers) at its southern end. The perspective changes greatly along the strip: at its northern end, the view looks out horizontally across the surface, while at its southern end, the view looks straight down onto the surface. This movie pans down the mosaic from top to bottom, offering new views of many of Pluto's distinct landscapes along the way. Starting with hummocky, cratered uplands at top, the view crosses over parallel ridges of the "washboard" terrain; chaotic and angular mountain ranges; the craterless, cellular plains; coarsely "pitted" areas of sublimating nitrogen ice; zones of thin nitrogen ice draped over the topography below; and rugged, dark, mountainous highlands scarred by deep pits. The frames in the movie were obtained by New Horizons' Long Range Reconnaissance Imager (LORRI) approximately 9,850 miles (15,850 kilometers) from Pluto, about 23 minutes before New Horizons' closest approach. LORRI is only capable of obtaining black-and-white images; all color images are made by the Ralph instrument, which has somewhat lower resolution than LORRI. Movies are available at http://photojournal.jpl.nasa.gov/catalog/PIA14457

Expandable stents.

PubMed

Nesbitt, J C; Carrasco, H

1996-05-01

Expandable metallic stents are effective in selected patients with malignant or benign airway stenoses. When used for malignant lesions, the primary purpose of the stent is to improve the quality of life; stents are usually chosen for palliation of symptoms in recognition of the low likelihood of success for other therapy. For patients with benign stenoses, the stents provide a permanent source of structural support to alleviate the narrowed segment. The advantages of the expandable metallic stents are as follows: (1) they can be inserted through an endotracheal tube or under local anesthesia with relative simplicity under fluoroscopic guidance; (2) they do not impair the drainage of sputum because ciliary movement is not interrupted; (3) over a period of a few weeks, the meshwork is gradually covered with mucosa as the stent becomes incorporated into the airway wall; (4) ventilation usually is not impaired if the metallic mesh stent covers another nonstenosed bronchus, because the interstices of the stent are nonobstructive; and (5) they are dynamic and continue to expand over time, particularly if concurrent treatment achieves an effect on the lesion that caused stenosis. Disadvantages of the expandable stent include (1) they often are only temporarily effective for tracheobronchial stenosis due to intraluminal tumor or granulation tissue, both of which can grow between the wires; (2) they are considered permanent stents because removal is difficult; and (3) they can be poorly positioned during placement or can become displaced by progressive migration after placement, and they cannot be repositioned. A relative contraindication to insertion is an inflammatory process or infection that can predispose to granulation formation, particularly at the points of maximal contact pressure of the stent to the airway mucosa. In the presence of inflammation, it may be better to use a silicone prosthesis until the inflammatory process subsides and fibrosis occurs. Granulation

Digital Signal Processing for the Event Horizon Telescope

NASA Astrophysics Data System (ADS)

Weintroub, Jonathan

2015-08-01

A broad international collaboration is building the Event Horizon Telescope (EHT). The aim is to test Einstein’s theory of General Relativity in one of the very few places it could break down: the strong gravity regime right at the edge of a black hole. The EHT is an earth-size VLBI array operating at the shortest radio wavelengths, that has achieved unprecedented angular resolution of a few tens of μarcseconds. For nearby super massive black holes (SMBH) this size scale is comparable to the Schwarzschild Radius, and emission in the immediate neighborhood of the event horizon can be directly observed. We give an introduction to the science behind the CASPER-enabled EHT, and outline technical developments, with emphasis on the secret sauce of high speed signal processing.

American Fuel Cell Bus Project Evaluation. Second Report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Eudy, Leslie; Post, Matthew

2015-09-01

This report presents results of the American Fuel Cell Bus (AFCB) Project, a demonstration of fuel cell electric buses operating in the Coachella Valley area of California. The prototype AFCB was developed as part of the Federal Transit Administration's (FTA's) National Fuel Cell Bus Program. Through the non-profit consortia CALSTART, a team led by SunLine Transit Agency and BAE Systems developed a new fuel cell electric bus for demonstration. SunLine added two more AFCBs to its fleet in 2014 and another in 2015. FTA and the AFCB project team are collaborating with the U.S. Department of Energy (DOE) and DOE'smore » National Renewable Energy Laboratory to evaluate the buses in revenue service. This report summarizes the performance results for the buses through June 2015.« less

New Horizons Best Close-Up of Pluto Surface

NASA Image and Video Library

2016-05-27

This mosaic strip, extending across the hemisphere that faced the New Horizons spacecraft as it flew past Pluto on July 14, 2015, now includes all of the highest-resolution images taken by the NASA probe.

Pedogenetic processes in anthrosols with pretic horizon (Amazonian Dark Earth) in Central Amazon, Brazil.

PubMed

Macedo, Rodrigo S; Teixeira, Wenceslau G; Corrêa, Marcelo M; Martins, Gilvan C; Vidal-Torrado, Pablo

2017-01-01

Anthrosols known as Amazonian Dark Earth (ADE) have borne witness to the intensification of sedentary patterns and the demographic increase in Central Amazon. As a result, a recurring pattern has been observed of mounds with ADE arising from domestic activities and the disposal of waste. The objective of this research was to demonstrate the relationship of these anthropic activities with pedogenetic formation processes of ADE in the municipality of Iranduba, Brazil. Disturbed and undisturbed soil samples were taken from two areas of ADE (pretic horizon) and from a non-anthropic pedon. Physical, chemical, micromorphological and SEM-EDS analyses were performed. The coarse material of the pretic horizons consisted predominantly of quartz, iron nodules, ceramics and charcoal fragments, and the fine material is organo-mineral. There was a direct relationship between the color of pretic horizons and the number of charcoal fragments. The thickness of the ADE results from the redistribution of charcoal at depth through bioturbation, transforming subsurface horizons into anthropic horizons. ADE presents granular microaggregates of geochemical and zoogenetic origin. Degradation of iron nodules is intensified in pretic horizons, promoting a reverse pedogenic process contributing to the xanthization process. Surprisingly the anthropic activities also favor clay dispersion and argilluviation; clay coatings on the ceramic fragments and in the pores demonstrate that this is a current process. Processes identified as contributing to ADE genesis included: i) addition of organic residues and ceramic artifacts (cumulization) with the use of fire; ii) mechanical action of humans, roots and macrofauna (bioturbation); iii) melanization of deeper horizons as a result of bioturbation; iv) argilluviation and degradation of iron nodules. This study offers new support to archaeological research in respect to ADE formation processes in Central Amazon and confirmed the hypothesis that ancient

Pedogenetic processes in anthrosols with pretic horizon (Amazonian Dark Earth) in Central Amazon, Brazil

PubMed Central

Macedo, Rodrigo S.; Teixeira, Wenceslau G.; Corrêa, Marcelo M.; Martins, Gilvan C.

2017-01-01

Anthrosols known as Amazonian Dark Earth (ADE) have borne witness to the intensification of sedentary patterns and the demographic increase in Central Amazon. As a result, a recurring pattern has been observed of mounds with ADE arising from domestic activities and the disposal of waste. The objective of this research was to demonstrate the relationship of these anthropic activities with pedogenetic formation processes of ADE in the municipality of Iranduba, Brazil. Disturbed and undisturbed soil samples were taken from two areas of ADE (pretic horizon) and from a non-anthropic pedon. Physical, chemical, micromorphological and SEM-EDS analyses were performed. The coarse material of the pretic horizons consisted predominantly of quartz, iron nodules, ceramics and charcoal fragments, and the fine material is organo-mineral. There was a direct relationship between the color of pretic horizons and the number of charcoal fragments. The thickness of the ADE results from the redistribution of charcoal at depth through bioturbation, transforming subsurface horizons into anthropic horizons. ADE presents granular microaggregates of geochemical and zoogenetic origin. Degradation of iron nodules is intensified in pretic horizons, promoting a reverse pedogenic process contributing to the xanthization process. Surprisingly the anthropic activities also favor clay dispersion and argilluviation; clay coatings on the ceramic fragments and in the pores demonstrate that this is a current process. Processes identified as contributing to ADE genesis included: i) addition of organic residues and ceramic artifacts (cumulization) with the use of fire; ii) mechanical action of humans, roots and macrofauna (bioturbation); iii) melanization of deeper horizons as a result of bioturbation; iv) argilluviation and degradation of iron nodules. This study offers new support to archaeological research in respect to ADE formation processes in Central Amazon and confirmed the hypothesis that ancient

Inner cauchy horizon of axisymmetric and stationary black holes with surrounding matter in einstein-maxwell theory.

PubMed

Ansorg, Marcus; Hennig, Jörg

2009-06-05

We study the interior electrovacuum region of axisymmetric and stationary black holes with surrounding matter and find that there exists always a regular inner Cauchy horizon inside the black hole, provided the angular momentum J and charge Q of the black hole do not vanish simultaneously. In particular, we derive an explicit relation for the metric on the Cauchy horizon in terms of that on the event horizon. Moreover, our analysis reveals the remarkable universal relation (8piJ);{2}+(4piQ;{2});{2}=A;{+}A;{-}, where A+ and A- denote the areas of event and Cauchy horizon, respectively.

Echoes from the abyss: Tentative evidence for Planck-scale structure at black hole horizons

NASA Astrophysics Data System (ADS)

Abedi, Jahed; Dykaar, Hannah; Afshordi, Niayesh

2017-10-01

In classical general relativity (GR), an observer falling into an astrophysical black hole is not expected to experience anything dramatic as she crosses the event horizon. However, tentative resolutions to problems in quantum gravity, such as the cosmological constant problem, or the black hole information paradox, invoke significant departures from classicality in the vicinity of the horizon. It was recently pointed out that such near-horizon structures can lead to late-time echoes in the black hole merger gravitational wave signals that are otherwise indistinguishable from GR. We search for observational signatures of these echoes in the gravitational wave data released by the advanced Laser Interferometer Gravitational-Wave Observatory (LIGO), following the three black hole merger events GW150914, GW151226, and LVT151012. In particular, we look for repeating damped echoes with time delays of 8 M log M (+spin corrections, in Planck units), corresponding to Planck-scale departures from GR near their respective horizons. Accounting for the "look elsewhere" effect due to uncertainty in the echo template, we find tentative evidence for Planck-scale structure near black hole horizons at false detection probability of 1% (corresponding to 2.5 σ

Weathered Oil and Tar Sampling Data for BP Spill/Deepwater Horizon

EPA Pesticide Factsheets

The Deepwater Horizon oil spill (also referred to as the BP oil spill) began on 20 April 2010 in the Gulf of Mexico on the BP-operated Macondo Prospect. Following the explosion and sinking of the Deepwater Horizon oil rig, a sea-floor oil gusher flowed for 87 days, until it was capped on 15 July 2010.In response to the BP oil spill, EPA sampled air, water, sediment, and waste generated by the cleanup operations.

Is the Gravitational-Wave Ringdown a Probe of the Event Horizon?

PubMed

Cardoso, Vitor; Franzin, Edgardo; Pani, Paolo

2016-04-29

It is commonly believed that the ringdown signal from a binary coalescence provides a conclusive proof for the formation of an event horizon after the merger. This expectation is based on the assumption that the ringdown waveform at intermediate times is dominated by the quasinormal modes of the final object. We point out that this assumption should be taken with great care, and that very compact objects with a light ring will display a similar ringdown stage, even when their quasinormal-mode spectrum is completely different from that of a black hole. In other words, universal ringdown waveforms indicate the presence of light rings, rather than of horizons. Only precision observations of the late-time ringdown signal, where the differences in the quasinormal-mode spectrum eventually show up, can be used to rule out exotic alternatives to black holes and to test quantum effects at the horizon scale.

The NMC Horizon Report: 2013 Museum Edition

ERIC Educational Resources Information Center

Johnson, L.; Adams Becker, S.; Freeman, A.

2013-01-01

The "NMC Horizon Report: 2013 Museum Edition," is a co-production with the Marcus Institute for Digital Education in the Arts (MIDEA), and examines six emerging technologies for their potential impact on and use in education and interpretation within the museum environment: BYOD (Bring Your Own Device), crowdsourcing, electronic…

Sighting Horizons of Teaching in Higher Education

ERIC Educational Resources Information Center

Barnett, Ronald; Guzmán-Valenzuela, Carolina

2017-01-01

This conceptual paper tackles the matter of teaching in higher education and proposes a concept of "horizons of teaching." It firstly offers an overview of the considerable empirical literature around teaching--especially conceptions of teaching, approaches to teaching and teaching practices--and goes on to pose some philosophical and…

What Expands in an Expanding Universe?

PubMed

Pacheco, José A De Freitas

2015-01-01

In the present investigation, the possible effects of the expansion of the Universe on systems bonded either by gravitational or electromagnetic forces, are reconsidered. It will be shown that the acceleration (positive or negative) of the expanding background, is the determinant factor affecting planetary orbits and atomic sizes. In the presently accepted cosmology (ΛCDM) all bonded systems are expanding at a decreasing rate that tends to be zero as the universe enters in a de Sitter phase. It is worth mentioning that the estimated expansion rates are rather small and they can be neglected for all practical purposes.

50 CFR 622.14 - Area closures related to the Deepwater Horizon oil spill.

Code of Federal Regulations, 2013 CFR

2013-10-01

... Web site: http://sero.nmfs.noaa.gov/deepwater_horizon_oil_spill.htm. (b) Gulf EEZ area closure related... the Gulf EEZ identified in the map shown on the NMFS Web site: http://sero.nmfs.noaa.gov/deepwater... shown on the NMFS Web site: http://sero.nmfs.noaa.gov/deepwater_horizon_oil_spill.htm. ...

New Horizons Educator Fellowship Program: Taking You to Pluto

NASA Astrophysics Data System (ADS)

Weir, H. M.; Beisser, K.; Hallau, K. G.

2011-12-01

The New Horizons Educator Fellowship Program (NHEFP), originally based on the MESSENGER Fellows Program, is a public outreach initiative for motivated volunteers across the nation. These volunteers are master teachers who communicate the excitement of NASA's New Horizons mission to Pluto and information about recent discoveries to teachers, students, and people in their local communities. Many of the Fellows utilize their experiences and knowledge as members of other programs such as MESSENGER Fellows, Heliophysics Educator Ambassadors, Solar System Educators and Ambassadors to promote the mission thorough professional development workshops incorporating themes, activities, and recent discoveries with other NASA programs to present a well-rounded view of our Solar System. Unlike teacher-volunteer programs tied to missions that take place closer to Earth, the time between New Horizons' launch and its closest approach to Pluto is 9.5 years, with the spacecraft in hibernation for most of its voyager. NHEFP has maintained a core group of Fellows who, through periodic face-to-face or remote training, have taken advantage of opportunities for networking, sharing of ideas in best practices, activities, and presenting and keeping audiences interested in the mission during its long journey to Pluto. This involvement has been key to the program's success.

A Benders based rolling horizon algorithm for a dynamic facility location problem

DOE PAGES

Marufuzzaman,, Mohammad; Gedik, Ridvan; Roni, Mohammad S.

2016-06-28

This study presents a well-known capacitated dynamic facility location problem (DFLP) that satisfies the customer demand at a minimum cost by determining the time period for opening, closing, or retaining an existing facility in a given location. To solve this challenging NP-hard problem, this paper develops a unique hybrid solution algorithm that combines a rolling horizon algorithm with an accelerated Benders decomposition algorithm. Extensive computational experiments are performed on benchmark test instances to evaluate the hybrid algorithm’s efficiency and robustness in solving the DFLP problem. Computational results indicate that the hybrid Benders based rolling horizon algorithm consistently offers high qualitymore » feasible solutions in a much shorter computational time period than the standalone rolling horizon and accelerated Benders decomposition algorithms in the experimental range.« less

RTG-History, the Curiosity, Voyager, and New Horizons

Science.gov Websites

solar system for many years. Prior to New Horizons, the Apollo missions to the Moon, the Viking missions Report, January 11, 1991--April 30, 1998, DOE Technical Report Download Adobe PDF Reader , August 1998

New Horizons Encountering 2014 MU69 (Artist's Impression)

NASA Image and Video Library

2018-01-04

Artist's impression of NASA's New Horizons spacecraft encountering 2014 MU69, a Kuiper Belt object that orbits one billion miles (1.6 billion kilometers) beyond Pluto, on Jan. 1, 2019. https://photojournal.jpl.nasa.gov/catalog/PIA22190

Horizon Brightness Revisited: Measurements and a Model of Clear-Sky Radiances

DTIC Science & Technology

1994-07-20

Clear daytime skies persistently display a subtle local maximum of radiance near the astronomical horizon. Spectroradiometry and digital image analysis confirm this maximum’s reality, and they show that its angular width and elevation vary with solar elevation, azimuth relative to the Sun, and aerosol optical depth. Many existing models of atmospheric scattering do not generate this near-horizon radiance maximum, but a simple second-order scattering model does, and it reproduces many of the maximum’s details.

75 FR 36773 - Pipeline Safety: Updating Facility Response Plans in Light of the Deepwater Horizon Oil Spill

Federal Register 2010, 2011, 2012, 2013, 2014

2010-06-28

.... PHMSA-2010-0175] Pipeline Safety: Updating Facility Response Plans in Light of the Deepwater Horizon Oil... 194. In light of the Deepwater Horizon oil spill in the Gulf of Mexico, which has resulted in the... Systems. Subject: Updating Facility Response Plans in Light of the Deepwater Horizon Oil Spill. Advisory...

Atmospheric Results from the MGS Horizon Science Experiment

NASA Technical Reports Server (NTRS)

Martin, T. Z.; Murphy, J. R.; Hollingsworth, J. L.

1999-01-01

The Horizon Science Experiment (HORSE) utilizes the Mars Horizon Sensor Assembly (MHSA) on the Mars Global Surveyor (MGS) orbiter to measure 15-micron band thermal emission from the Martian atmosphere. During the first two phases of aerobraking, from September 1997 to May 1998, and from September 1998 to March 1999, one of the four MGS quadrants was pointed well onto the planet consistently during the near-periapsis aerobraking passes, allowing the device to obtain data on the latitudinal variation of middle atmospheric temperature (0.2 - 2.0 mbar). Of particular interest during the first phase (L(sub s) = 182 - 300 deg) were the effects of a prominent dust storm at L(sub s) =224 deg, and wavelike behavior in the strong temperature gradient near the north polar cap. Additional information is contained in the original extended abstract.

Time-Symmetric Quantization in Spacetimes with Event Horizons

NASA Astrophysics Data System (ADS)

Kobakhidze, Archil; Rodd, Nicholas

2013-08-01

The standard quantization formalism in spacetimes with event horizons implies a non-unitary evolution of quantum states, as initial pure states may evolve into thermal states. This phenomenon is behind the famous black hole information loss paradox which provoked long-standing debates on the compatibility of quantum mechanics and gravity. In this paper we demonstrate that within an alternative time-symmetric quantization formalism thermal radiation is absent and states evolve unitarily in spacetimes with event horizons. We also discuss the theoretical consistency of the proposed formalism. We explicitly demonstrate that the theory preserves the microcausality condition and suggest a "reinterpretation postulate" to resolve other apparent pathologies associated with negative energy states. Accordingly as there is a consistent alternative, we argue that choosing to use time-asymmetric quantization is a necessary condition for the black hole information loss paradox.

75 FR 26091 - Safety Zone; Riser for DEEPWATER HORIZON at Mississippi Canyon 252 Outer Continental Shelf MODU...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-05-11

... establishing a safety zone around the riser for the DEEPWATER HORIZON, a Mobile Offshore Drilling Unit (MODU... Mexico in response to the sinking of the DEEPWATER HORIZON, a Mobile Offshore Drilling Unit (MODU), which.... 147.T08-849 to read as follows: Sec. 147.T08-849 DEEPWATER HORIZON Mobile Offshore Drilling Unit...

[Horizon 2020, new EU Framework programme for research and innovation, 2014-2020].

PubMed

Kinkorová, Judita

2014-01-01

Horizon 2020 is a financial instrument implementing the Innovation Union, a Europe 2020 flagship initiative aimed at securing Europes global competitiveness. Running from 2014 to 2020 with a budget of just over € 80 billion, the EUs new programme for research and innovation is part of the drive to create new growth and jobs in Europe. Societal challenge Health, demographic change and wellbeing is an important part of Horizon 2020.

Expandable space frames

NASA Technical Reports Server (NTRS)

Schoen, A. H. (Inventor)

1973-01-01

Expandable space frames having essentially infinite periodicity limited only by practical considerations, are described. Each expandable space frame comprises a plurality of hinge joint assemblies having arms that extend outwardly in predetermined symmetrically related directions from a central or vertex point. The outer ends of the arms form one part of a hinge point. The outer expandable space frame also comprises a plurality of struts. The outer ends of the struts from the other part of the hinged joint. The struts interconnect the plurality of hinge point in sychronism, the spaceframes can be expanded or collapsed. Three-dimensional as well as two-dimensional spaceframes of this general nature are described.

MSSA de-noising of horizon time structure to improve the curvature attribute analysis

NASA Astrophysics Data System (ADS)

Tiwari, R. K.; Rekapalli, R.; Vedanti, N.

2017-12-01

Although the seismic attributes are useful for identifying sub-surface structural features like faults, fractures, lineaments and sharp stratigraphy etc., the different kinds of noises arising from unknown physical sources during the data acquisition and processing creates acute problems in physical interpretation of complex crustal structures. Hence, we propose to study effect of noise on curvature attribute analysis of seismic time structure data. We propose here Multichannel Singular Spectrum Analysis (MSSA) de-noising algorithm as a pre filtering scheme to reduce effect of noise. To demonstrate the procedure, first, we compute the most positive and negative curvature on a synthetic time structure with surface features resembling anticlines, synclines and faults and then adding the known percentage of noise. We noticed that the curvatures estimated from the noisy data reveal considerable deviations from the curvature of pure synthetic data. This suggests that there is a strong impact of noise on the curvature estimates. Further, we have employed 2D median filter and MSSA methods to filter the noisy time structure and then computed the curvatures. The comparisons of curvatures estimated from de-noised data suggest that the results obtained from MSSA de-noised data match well with the curvatures of pure synthetic data. Finally, we present an example of real data analysis from Utsira Top (UT) horizon of Southern Viking Graben, Norway to identify the time-lapse changes in UT horizon after CO2 injection. We applied the MSSA de-noising algorithm on UT horizon time structure and amplitude data of pre and post CO2 injection. Our analyses suggest modest but clearly visible, structural changes in the UT horizon after CO2 injection at a few locations, which seem to be associated with the locations of change in seismic amplitudes. Thus, the results from both the synthetic and real field data suggest that the MSSA based de-noising algorithm is robust for filtering the

Expanded U.S. mid-Atlantic Margin Deep-Water Allostratigraphy; Bottom-Current Controls on Margin Evolution

NASA Astrophysics Data System (ADS)

Gibson, J. C.; Miller, N. C.; Hutchinson, D. R.; Ten Brink, U. S.; Mountain, G. S.; Chaytor, J. D.; Shillington, D. J.

2017-12-01

There is a long history of seismic stratigraphic interpretation/analysis of the sedimentary sequence along the U.S. mid-Atlantic Margin (MAM). Here we expand the allostratigraphic (unconformity-bound) framework from the outer continental shelf to the Hatteras Abyssal Plain by correlating recently acquired 2D multi-channel seismic reflection data with existing drill sites and legacy 2D seismic data collected over the past 42 yrs. The new 2D post-stack Kirchhoff time migrated seismic data were acquired using R/V Marcus G. Langseth in 2014-2015 during USGS ECS surveys MGL1407 & MGL1506 and NSF-funded ENAM-CSE survey MGL1408. We map six seismic horizons along 1.5x104 km of 2D data and tie each to stratigraphic unconformities sampled at DSDP site 603 (lower rise). From shallow to deep they are: (1) M2, latest Miocene; (2) X, middle Miocene; (3) Au, late Oligocene; (4) A*, Late Cretaceous; (5) Km, early Late Cretaceous; and (6) Beta, middle Early Cretaceous. The horizons were converted to depth (mbsl) using high-resolution interval velocity models generated for each 2D survey line and isopachs were produced using the depth-converted stratigraphic framework for each allostratigraphic unit. The time-to-depth function was confirmed to be within 5% of drilling results at DSDP Sites 603 and nearby 105. Additionally, we tie horizon Au to upper-slope ODP Sites 902 & 1073, and trace it to the outer shelf. Interpretation of the framework and resulting isopachs show total sediment thickness uniformly decreasing seaward from the shelf edge, and overall thickening to the south. Regional depositional trends display a combination of both down slope and along slope processes (e.g. mass wasting, submarine fan formation, contourite and sediment drift deposits). The unit bound by horizons Au & Beta confirms pervasive excavation from the mid-slope to the continental rise and across the central and southern MAM (from New Jersey to North Carolina). How the excavated sediments were

AdS3 to dS3 transition in the near horizon of asymptotically de Sitter solutions

NASA Astrophysics Data System (ADS)

Sadeghian, S.; Vahidinia, M. H.

2017-08-01

We consider two solutions of Einstein-Λ theory which admit the extremal vanishing horizon (EVH) limit, odd-dimensional multispinning Kerr black hole (in the presence of cosmological constant) and cosmological soliton. We show that the near horizon EVH geometry of Kerr has a three-dimensional maximally symmetric subspace whose curvature depends on rotational parameters and the cosmological constant. In the Kerr-dS case, this subspace interpolates between AdS3 , three-dimensional flat and dS3 by varying rotational parameters, while the near horizon of the EVH cosmological soliton always has a dS3 . The feature of the EVH cosmological soliton is that it is regular everywhere on the horizon. In the near EVH case, these three-dimensional parts turn into the corresponding locally maximally symmetric spacetimes with a horizon: Kerr-dS3 , flat space cosmology or BTZ black hole. We show that their thermodynamics match with the thermodynamics of the original near EVH black holes. We also briefly discuss the holographic two-dimensional CFT dual to the near horizon of EVH solutions.

NASA’s Aerial Survey of Polar Ice Expands Its Arctic Reach

NASA Image and Video Library

2017-12-08

For the past eight years, Operation IceBridge, a NASA mission that conducts aerial surveys of polar ice, has produced unprecedented three-dimensional views of Arctic and Antarctic ice sheets, providing scientists with valuable data on how polar ice is changing in a warming world. Now, for the first time, the campaign will expand its reach to explore the Arctic’s Eurasian Basin through two research flights based out of Svalbard, a Norwegian archipelago in the northern Atlantic Ocean. More: go.nasa.gov/2ngAxX2 Caption: Ellesmere Island mountain tops bathed in light as the sun began to peak over the horizon during Operation IceBridge’s first flight of its 2017 Arctic campaign, on March 9, 2017. Credits: NASA/Nathan Kurtz NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Like us on Facebook Find us on Instagram

Mercury in litterfall and upper soil horizons in forested ecosystems in Vermont, USA.

PubMed

Juillerat, Juliette I; Ross, Donald S; Bank, Michael S

2012-08-01

Mercury (Hg) is an atmospheric pollutant that, in forest ecosystems, accumulates in foliage and upper soil horizons. The authors measured soil and litterfall Hg at 15 forest sites (northern hardwood to mixed hardwood/conifer) throughout Vermont, USA, to examine variation among tree species, forest type, and soils. Differences were found among the 12 tree species sampled from at least two sites, with Acer pensylvanicum having significantly greater litterfall total Hg concentration. Senescent leaves had greater Hg concentrations if they originated lower in the canopy or had higher surface:weight ratios. Annual litterfall Hg flux had a wide range, 12.6 to 28.5 µg/m(2) (mean, 17.9 µg/m(2) ), not related to forest type. Soil and Hg pools in the Oi horizon (litter layer) were not related to the measured Hg deposition flux in litterfall or to total modeled Hg deposition. Despite having lower Hg concentrations, upper mineral soil (A horizons) had greater Hg pools than organic soil horizons (forest floor) due to greater bulk density. Significant differences were found in Hg concentration and Hg/C ratio among soil horizons but not among forest types. Overall, our findings highlight the importance of site history and the benefits of collecting litterfall and soils simultaneously. Observed differences in forest floor Hg pools were strongly correlated with carbon pools, which appeared to be a function of historic land-use patterns. Copyright © 2012 SETAC.

A horizon scan of global conservation issues for 2012.

PubMed

Sutherland, William J; Aveling, Ros; Bennun, Leon; Chapman, Eleanor; Clout, Mick; Côté, Isabelle M; Depledge, Michael H; Dicks, Lynn V; Dobson, Andrew P; Fellman, Liz; Fleishman, Erica; Gibbons, David W; Keim, Brandon; Lickorish, Fiona; Lindenmayer, David B; Monk, Kathryn A; Norris, Kenneth; Peck, Lloyd S; Prior, Stephanie V; Scharlemann, Jörn P W; Spalding, Mark; Watkinson, Andrew R

2012-01-01

Our aim in conducting annual horizon scans is to identify issues that, although currently receiving little attention, may be of increasing importance to the conservation of biological diversity in the future. The 15 issues presented here were identified by a diverse team of 22 experts in horizon scanning, and conservation science and its application. Methods for identifying and refining issues were the same as in two previous annual scans and are widely transferable to other disciplines. The issues highlight potential changes in climate, technology and human behaviour. Examples include warming of the deep sea, increased cultivation of perennial grains, burning of Arctic tundra, and the development of nuclear batteries and hydrokinetic in-stream turbines. Copyright © 2011 Elsevier Ltd. All rights reserved.

The 2010 Deepwater Horizon oil spill: the trauma signature of an ecological disaster.

PubMed

Shultz, James M; Walsh, Lauren; Garfin, Dana Rose; Wilson, Fiona E; Neria, Yuval

2015-01-01

The 2010 Deepwater Horizon “British Petroleum (BP)” oil spill was a mega-disaster characterized as the petroleum industry’s largest-volume marine oil spill in history. Following a “wellhead blowout” that destroyed the drilling platform, 4.9 million barrels of petroleum flowed into the Gulf of Mexico over 87 days and the spill expanded to cover 68,000 square miles of sea surface. However, despite the expansive scope of the event, systematic surveys of affected coastal populations found only modest effects on mental health and substance abuse. An established trauma signature (TSIG) methodology was used to examine the psychological consequences in relation to exposure to the unique constellation of hazards associated with the spill. A hazard profile, a matrix of psychological stressors, and a “trauma signature” summary for the affected Gulf Coast population--in terms of exposure to hazard, loss, and change--were created specifically for this human-generated ecological disaster. Psychological risk characteristics of this event included: human causation featuring corporate culpability, large spill volume, protracted duration, coastal contamination from petroleum products, severe ecological damage, disruption of Gulf Coast industries and tourism, and extensive media coverage. The multiple impact effect was notable due to prior exposure of the region to Hurricane Katrina. These stressors were counterbalanced by the relative absence of other prominent risks for distress and psychopathology. Coastal residents did not experience significant onshore spill-related mortality or severe injury, shortages of survival needs, disruption of vital services (health care, schools, utilities, communications, and transportation), loss of homes, population displacement, destruction of the built environment, or loss of social supports. Initial acute economic losses were partially offset by large-sum BP payments for cleanup and recovery of the coastal economy. Not only did Gulf

From the lab - Noninvasive Lung Cancer Testing on the Horizon | NIH MedlinePlus the Magazine

MedlinePlus

... Cancer Testing on the Horizon Follow us Noninvasive Lung Cancer Testing on the Horizon A team of scientists, ... the nose and lung samples of patients with lung cancer. Studies have shown that the activity of certain ...

Energy and information near black hole horizons

DOE Office of Scientific and Technical Information (OSTI.GOV)

Freivogel, Ben, E-mail: benfreivogel@gmail.com

2014-07-01

The central challenge in trying to resolve the firewall paradox is to identify excitations in the near-horizon zone of a black hole that can carry information without injuring a freely falling observer. By analyzing the problem from the point of view of a freely falling observer, I arrive at a simple proposal for the degrees of freedom that carry information out of the black hole. An infalling observer experiences the information-carrying modes as ingoing, negative energy excitations of the quantum fields. In these states, freely falling observers who fall in from infinity do not encounter a firewall, but freely fallingmore » observers who begin their free fall from a location close to the horizon are ''frozen'' by a flux of negative energy. When the black hole is ''mined,'' the number of information-carrying modes increases, increasing the negative energy flux in the infalling frame without violating the equivalence principle. Finally, I point out a loophole in recent arguments that an infalling observer must detect a violation of unitarity, effective field theory, or free infall.« less

Radio Occultation Measurements of Pluto’s Atmosphere with New Horizons

NASA Astrophysics Data System (ADS)

Hinson, David P.; Linscott, Ivan; Tyler, Len; Bird, Mike; Paetzold, Martin; Strobel, Darrell; Summers, Mike; Woods, Will; Stern, Alan; Weaver, Hal; Olkin, Cathy; Young, Leslie; Ennico, Kimberly; Gladstone, Randy; Greathouse, Tommy; Kammer, Josh; Parker, Alex; Parker, Joel; Retherford, Kurt; Schindhelm, Eric; Singer, Kelsi; Steffl, Andrew; Tsang, Con; Versteeg, Maarten

2015-11-01

The reconnaissance of the Pluto System by New Horizons included radio occultations at both Pluto and Charon. This talk will present the latest results from the Pluto occultation. The REX instrument onboard New Horizons received and recorded uplink signals from two 70-m antennas and two 34-m antennas of the NASA Deep Space Network - each transmitting 20 kW at 4.2-cm wavelength - during a diametric occultation by Pluto. At the time this was written only a short segment of data at occultation entry (193°E, 17°S) was available for analysis. The REX measurements extend unequivocally to the surface, providing the first direct measure of the surface pressure and the temperature structure in Pluto’s lower atmosphere. Data from occultation exit (16°E, 15°N) are scheduled to arrive on the ground in late August 2015. Those observations will yield an improved estimate of the surface pressure, a second temperature profile, and a measure of the diameter of Pluto with a precision of a few hundred meters. This work is supported by the NASA New Horizons Mission.

Symmetry enhancement of extremal horizons in D  =  5 supergravity

NASA Astrophysics Data System (ADS)

Kayani, U.

2018-06-01

We consider the near-horizon geometry of supersymmetric extremal black holes in un-gauged and gauged 5-dimensional supergravity, coupled to abelian vector multiplets. By analyzing the global properties of the Killing spinors, we prove that the near-horizon geometries undergo a supersymmetry enhancement. This follows from a set of generalized Lichnerowicz-type theorems we establish, together with an index theory argument. As a consequence, these solutions always admit a symmetry group.

Entropy of Vaidya Black Hole on Apparent Horizon with Minimal Length Revisited

NASA Astrophysics Data System (ADS)

Tang, Hao; Wu, Bin; Sun, Cheng-yi; Song, Yu; Yue, Rui-hong

2018-03-01

By considering the generalized uncertainty principle, the degrees of freedom near the apparent horizon of Vaidya black hole are calculated with the thin film model. The result shows that a cut-off can be introduced naturally rather than taking by hand. Furthermore, if the minimal length is chosen to be a specific value, the statistical entropy will satisfy the conventional area law at the horizon, which might reveal some deep things of the minimal length.

Entropy of Vaidya Black Hole on Apparent Horizon with Minimal Length Revisited

NASA Astrophysics Data System (ADS)

Tang, Hao; Wu, Bin; Sun, Cheng-yi; Song, Yu; Yue, Rui-hong

2018-07-01

By considering the generalized uncertainty principle, the degrees of freedom near the apparent horizon of Vaidya black hole are calculated with the thin film model. The result shows that a cut-off can be introduced naturally rather than taking by hand. Furthermore, if the minimal length is chosen to be a specific value, the statistical entropy will satisfy the conventional area law at the horizon, which might reveal some deep things of the minimal length.

Black hole event horizons — Teleology and predictivity

NASA Astrophysics Data System (ADS)

Bhattacharya, Swastik; Shankaranarayanan, S.

2017-11-01

General Relativity predicts the existence of black holes. Access to the complete spacetime manifold is required to describe the black hole. This feature necessitates that black hole dynamics is specified by future or teleological boundary condition. Here, we demonstrate that the statistical mechanical description of black holes, the raison d’être behind the existence of black hole thermodynamics, requires teleological boundary condition. Within the fluid-gravity paradigm — Einstein’s equations when projected on spacetime horizons resemble Navier-Stokes equation of a fluid — we show that the specific heat and the coefficient of bulk viscosity of the horizon fluid are negative only if the teleological boundary condition is taken into account. We argue that in a quantum theory of gravity, the future boundary condition plays a crucial role. We briefly discuss the possible implications of this at late stages of black hole evaporation.

Receding horizon online optimization for torque control of gasoline engines.

PubMed

Kang, Mingxin; Shen, Tielong

2016-11-01

This paper proposes a model-based nonlinear receding horizon optimal control scheme for the engine torque tracking problem. The controller design directly employs the nonlinear model exploited based on mean-value modeling principle of engine systems without any linearizing reformation, and the online optimization is achieved by applying the Continuation/GMRES (generalized minimum residual) approach. Several receding horizon control schemes are designed to investigate the effects of the integral action and integral gain selection. Simulation analyses and experimental validations are implemented to demonstrate the real-time optimization performance and control effects of the proposed torque tracking controllers. Copyright © 2016 ISA. Published by Elsevier Ltd. All rights reserved.

How Choice of Depth Horizon Influences the Estimated Spatial Patterns and Global Magnitude of Ocean Carbon Export Flux

NASA Astrophysics Data System (ADS)

Palevsky, Hilary I.; Doney, Scott C.

2018-05-01

Estimated rates and efficiency of ocean carbon export flux are sensitive to differences in the depth horizons used to define export, which often vary across methodological approaches. We evaluate sinking particulate organic carbon (POC) flux rates and efficiency (e-ratios) in a global earth system model, using a range of commonly used depth horizons: the seasonal mixed layer depth, the particle compensation depth, the base of the euphotic zone, a fixed depth horizon of 100 m, and the maximum annual mixed layer depth. Within this single dynamically consistent model framework, global POC flux rates vary by 30% and global e-ratios by 21% across different depth horizon choices. Zonal variability in POC flux and e-ratio also depends on the export depth horizon due to pronounced influence of deep winter mixing in subpolar regions. Efforts to reconcile conflicting estimates of export need to account for these systematic discrepancies created by differing depth horizon choices.

Central Radar System, Over-the-Horizon Backscatter

DTIC Science & Technology

1990-03-09

1,2-Dibromo-3- chloropropane (DBCP) 0.3 TABLE 41-6 (Continued). MINNESOTA RECOMMENDED ALLOWABLE LIMITS (RAL) FOR DRINKING WATER WELLS Compound RAL (ug/ 1 ...TABLE OF CONTENTS ENVIRONMENTAL IMPACT ANALYSIS PROCESS OVERVIEW ............ TECHNICAL STUDY 1 FACILITIES...TECHNICAL STUDY 10 0 TECHNICAL STUDY 1 CENTRAL RADAR SYSTEM OVER-THE-HORIZON BACKSCATTER RADAR PROGRAM 0 ENVIRONMENTAL IMPACT

75 FR 32273 - Safety Zone; DEEPWATER HORIZON at Mississippi Canyon 252 Outer Continental Shelf MODU in the Gulf...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-06-08

... establishing a continued safety zone around the riser for the DEEPWATER HORIZON, a Mobile Offshore Drilling... sinking of the DEEPWATER HORIZON, a Mobile Offshore Drilling Unit (MODU), near Mississippi Canyon 252 with... read as follows: Sec. 147.T08-849 DEEPWATER HORIZON Mobile Offshore Drilling Unit Safety Zone. (a...

75 FR 51943 - Safety Zone; DEEPWATER HORIZON at Mississippi Canyon 252 Outer Continental Shelf MODU in the Gulf...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-08-24

... the DEEPWATER HORIZON, a Mobile Offshore Drilling Unit (MODU), at Mississippi Canyon 252, in the Outer... the DEEPWATER HORIZON, a Mobile Offshore Drilling Unit (MODU), which is currently set to expire on... response to the sinking of the DEEPWATER HORIZON, a Mobile Offshore Drilling Unit (MODU), near Mississippi...

78 FR 55697 - Notice to All Interested Parties of the Termination of the Receivership of 10070, Horizon Bank...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-09-11

... Receivership of 10070, Horizon Bank, Pine City, MN Notice is hereby given that the Federal Deposit Insurance Corporation (``FDIC'') as Receiver for Horizon Bank, Pine City, Minnesota (``the Receiver'') intends to terminate its receivership for said institution. The FDIC was appointed receiver of Horizon Bank on June 26...

New black holes in D =5 minimal gauged supergravity: Deformed boundaries and frozen horizons

NASA Astrophysics Data System (ADS)

Blázquez-Salcedo, Jose Luis; Kunz, Jutta; Navarro-Lérida, Francisco; Radu, Eugen

2018-04-01

A new class of black hole solutions of the five-dimensional minimal gauged supergravity is presented. They are characterized by the mass, the electric charge, two equal magnitude angular momenta and the magnitude of the magnetic potential at infinity. These black holes possess a horizon of spherical topology; however, both the horizon and the sphere at infinity can be arbitrarily squashed, with nonextremal solutions interpolating between black strings and black branes. A particular set of extremal configurations corresponds to a new one-parameter family of supersymmetric black holes. While their conserved charges are determined by the squashing of the sphere at infinity, these supersymmetric solutions possess the same horizon geometry.

Community Colleges Broadening Horizons through Service Learning, 2003-2006. Project Brief. AACC-PB-04-2

ERIC Educational Resources Information Center

Robinson, Gail

2004-01-01

The "Horizons" project features model programs, national data collection and dissemination, and an information clearinghouse. In addition, "Horizons" provides professional development opportunities and technical assistance through regional workshops on service learning and civic responsibility, chief academic officer summits,…

Solar Array Panels and Earths Horizon during Expedition 13

NASA Image and Video Library

2006-07-24

ISS013-E-64485 (24 July 2006) --- Earth's horizon and station solar array panels are featured in this image photographed by an Expedition 13 crewmember from a window on the International Space Station.

Ecological impacts of the Deepwater Horizon oil spill

EPA Science Inventory

The Deepwater Horizon oil spill (DWH) was the largest environmental disaster and response effort in United States history, with nearly 800 million liters of crude oil spilled. Vast areas of the Gulf of Mexico were contaminated with oil, including deep ocean communities and over 1...

The ecological forecast horizon, and examples of its uses and determinants

PubMed Central

Petchey, Owen L; Pontarp, Mikael; Massie, Thomas M; Kéfi, Sonia; Ozgul, Arpat; Weilenmann, Maja; Palamara, Gian Marco; Altermatt, Florian; Matthews, Blake; Levine, Jonathan M; Childs, Dylan Z; McGill, Brian J; Schaepman, Michael E; Schmid, Bernhard; Spaak, Piet; Beckerman, Andrew P; Pennekamp, Frank; Pearse, Ian S; Vasseur, David

2015-01-01

Forecasts of ecological dynamics in changing environments are increasingly important, and are available for a plethora of variables, such as species abundance and distribution, community structure and ecosystem processes. There is, however, a general absence of knowledge about how far into the future, or other dimensions (space, temperature, phylogenetic distance), useful ecological forecasts can be made, and about how features of ecological systems relate to these distances. The ecological forecast horizon is the dimensional distance for which useful forecasts can be made. Five case studies illustrate the influence of various sources of uncertainty (e.g. parameter uncertainty, environmental variation, demographic stochasticity and evolution), level of ecological organisation (e.g. population or community), and organismal properties (e.g. body size or number of trophic links) on temporal, spatial and phylogenetic forecast horizons. Insights from these case studies demonstrate that the ecological forecast horizon is a flexible and powerful tool for researching and communicating ecological predictability. It also has potential for motivating and guiding agenda setting for ecological forecasting research and development. PMID:25960188

The late Barremian Halimedides horizon of the Dolomites (Southern Alps, Italy).

PubMed

Lukeneder, Alexander; Uchman, Alfred; Gaillard, Christian; Olivero, Davide

2012-06-01

A new trace fossil marker level, the Halimedides horizon, is proposed for the Lower Cretaceous pelagic to hemipelagic succession of the Puez area (Southern Alps, Italy). The horizon occurs in the middle part of the late Barremian Gerhardtia sartousiana Zone ( Gerhardtia sartousiana Subzone). It is approximately 20 cm thick and restricted to the uppermost part of the Puez Limestone Member (marly limestones; Hauterivian-Barremian; Puez Formation). It is fixed to the top 20 cm of bed P1/204. The grey-whitish limestone bed of the G. sartousiana Zone is penetrated by Aptian red marls-siltstones of the Redbed Member. The horizon is documented for the first time from the Southern Alps, including the Dolomites, and can be correlated with other Mediterranean localities. The trace fossil assemblage of this marker bed with the co-occurrence of Halimedides , Spongeliomorpha and Zoophycos sheds light on the Lower Cretaceous sedimentological history and current system of the Puez area within the Dolomites. It also highlights the palaeoenvironmental evolution of basins and plateaus and provides insights into the late Barremian interval.

The late Barremian Halimedides horizon of the Dolomites (Southern Alps, Italy)

PubMed Central

Lukeneder, Alexander; Uchman, Alfred; Gaillard, Christian; Olivero, Davide

2012-01-01

A new trace fossil marker level, the Halimedides horizon, is proposed for the Lower Cretaceous pelagic to hemipelagic succession of the Puez area (Southern Alps, Italy). The horizon occurs in the middle part of the late Barremian Gerhardtia sartousiana Zone (Gerhardtia sartousiana Subzone). It is approximately 20 cm thick and restricted to the uppermost part of the Puez Limestone Member (marly limestones; Hauterivian–Barremian; Puez Formation). It is fixed to the top 20 cm of bed P1/204. The grey–whitish limestone bed of the G. sartousiana Zone is penetrated by Aptian red marls–siltstones of the Redbed Member. The horizon is documented for the first time from the Southern Alps, including the Dolomites, and can be correlated with other Mediterranean localities. The trace fossil assemblage of this marker bed with the co-occurrence of Halimedides, Spongeliomorpha and Zoophycos sheds light on the Lower Cretaceous sedimentological history and current system of the Puez area within the Dolomites. It also highlights the palaeoenvironmental evolution of basins and plateaus and provides insights into the late Barremian interval. PMID:27087717

Stationary holographic plasma quenches and numerical methods for non-killing horizons.

PubMed

Figueras, Pau; Wiseman, Toby

2013-04-26

We explore use of the harmonic Einstein equations to numerically find stationary black holes where the problem is posed on an ingoing slice that extends into the interior of the black hole. Requiring no boundary conditions at the horizon beyond smoothness of the metric, this method may be applied for horizons that are not Killing. As a nontrivial illustration we find black holes which, via AdS-CFT, describe a time-independent CFT plasma flowing through a static spacetime which asymptotes to Minkowski in the flow's past and future, with a varying spatial geometry in between. These are the first nonperturbative examples of stationary black holes which do not have Killing horizons. When the CFT spacetime slowly varies, the CFT stress tensor derived from gravity is well described by viscous hydrodynamics. For fast variation it is not, and the solutions are stationary analogs of dynamical quenches, with the plasma being suddenly driven out of equilibrium. We find evidence these flows become unstable for sufficiently strong quenches, and speculate the instability may be turbulent.

Time Evolution of Meson Density During Formation of Expanding Quark-Antiquark System

NASA Astrophysics Data System (ADS)

Ghaffary, Tooraj

2018-04-01

Recently some researchers (Sepehri and Shoorvazi Astrophys. Spaces Sci. 344(2), 521-527, 2013) have considered the Universe as an acceleration cylindrical system. Motivated by their work and using their method in QCD, this paper has been cleared that because the acceleration of expansion in quark-antiquark system is relatively very large, one horizon is appeared outside the system. To obtain the total cross section of meson near this horizon, we need to multiply the production cross section for appeared horizon by the density of meson produced outside the system. As it can be seen by an observer who is outside the meson formation process, this cross section depends on time so the event horizon is now a time depended process.

Charged Particles' Hawking Radiation via Tunneling of Both Horizons from Reissner-Nordström-Taub-NUT Black Holes

NASA Astrophysics Data System (ADS)

Ali, M. Hossain; Sultana, Kausari

2013-08-01

In some recent derivations thermal characters of the inner horizon have been employed; however, the understanding of possible role that may play the inner horizons of black holes in black hole thermodynamics is still somewhat incomplete. Motivated by this problem we investigate Hawking radiation of the Reissner-Nordström-Taub-NUT (RNTN) black hole by considering thermal characters of both the outer and inner horizons. We apply Damour-Ruffini method and the thin film brick wall model to calculate the temperature and the entropy of the inner horizon of the RNTN black hole. The inner horizon admits thermal character with positive temperature and entropy proportional to its area, and it thus may contribute to the total entropy of the black hole in the context of Nernst theorem. Considering conservations of energy and charge and the back-reaction of emitting particles to the spacetime, the emission spectra are obtained for both the inner and outer horizons. The total emission rate is the product of the emission rates of the inner and outer horizons, and it deviates from the purely thermal spectrum and can bring some information out. Thus, the result can be treated as an explanation to the information loss paradox.

New Horizons Corrects Its Course in the Kuiper Belt

NASA Image and Video Library

2017-12-11

The New Horizons spacecraft is about 300 million miles (483 million kilometers) from 2014 MU69, the Kuiper Belt object it will encounter on Jan. 1, 2019. https://photojournal.jpl.nasa.gov/catalog/PIA22188

Deepwater Horizon – BP Gulf of Mexico Oil Spill

EPA Pesticide Factsheets

This webpage provides information and materials on EPA’s enforcement response to the Deepwater Horizon Oil Spill, including settlements with some of the defendants, as well as links to other related websites for additional information.

The interactive impact of root branch order and soil genetic horizon on root respiration and nitrogen concentration.

PubMed

Trocha, Lidia K; Bulaj, Bartosz; Kutczynska, Paulina; Mucha, Joanna; Rutkowski, Pawel; Zadworny, Marcin

2017-08-01

In general, respiration (RS) is highly correlated with nitrogen concentration (N) in plant organs, including roots, which exhibit a positive N-RS relationship. Less is known, however, about the relationship between N and RS in roots of different branch orders within an individual tree along a vertical soil profile; this is especially true in trees with contrasting life strategies, such as pioneer Scots pine (Pinus sylvestris L.) vs mid-successional sessile oak (Quercus petraea Liebl.). In the present research, the impact of root branch order, as represented by those with absorptive vs transporting ability, and soil genetic horizon on root N, RS and the N-RS relationship was examined. Mean RS and total N concentration differed significantly among root branch orders and was significantly higher in absorptive roots than in transporting roots. The soil genetic horizon differentially affected root RS in Scots pine vs sessile oak. The genetic horizon mostly affected RS in absorptive roots of Scots pine and transporting roots in sessile oak. Root N was the highest in absorptive roots and most affected by soil genetic horizon in both tree species. Root N was not correlated with soil N, although N levels were higher in roots growing in fertile soil genetic horizons. Overall, RS in different root branch orders was positively correlated with N in both species. The N-RS relationship in roots, pooled by soil genetic horizon, was significant in both species, but was only significant in sessile oak when roots were pooled by root branch order. In both tree species, a significant interaction was found between the soil genetic horizon and root branch order with root function; however, species-specific responses were found. Both root N, which was unaffected by soil N, and the positive N-RS relationship consistently observed in different genetic horizons suggest that root function prevails over environmental factors, such as soil genetic horizon. © The Author 2017. Published by

Black Hole Event Horizons and Advection-Dominated Accretion

NASA Technical Reports Server (NTRS)

McClintock, Jeffrey; Mushotzky, Richard F. (Technical Monitor)

2002-01-01

The work supported in part by this grant is part of a larger program on the detection of black hole event horizons, which is also partially supported by NASA grant GO0-1105A. This work has been carried out primarily in collaboration with Dr. M. Garcia and Prof. R. Narayan at the Harvard-Smithsonian Center for Astrophysics and with D. Barret and J. Hameury at Centre d'Etude Spoliate des Rayonnements, France. Our purpose is to confirm the existence of black-hole event horizons by comparing accreting black holes to secreting neutron stars in quiescent X-ray novae. Such a comparison is feasible because black holes and neutron stars are both present in similar environments in X-ray novae. Our second purpose is to assess the nature of accretion flows onto black holes at very low mass transfer rates. Observations of some XMM targets are still pending, whereas most of the Chandra observations have been completed. We anticipate further publications on this work in the future.

Direct Comparison of the Precision of the New Hologic Horizon Model With the Old Discovery Model.

PubMed

Whittaker, LaTarsha G; McNamara, Elizabeth A; Vath, Savoun; Shaw, Emily; Malabanan, Alan O; Parker, Robert A; Rosen, Harold N

2017-11-22

Previous publications suggested that the precision of the new Hologic Horizon densitometer might be better than that of the previous Discovery model, but these observations were confounded by not using the same participants and technologists on both densitometers. We sought to study this issue methodically by measuring in vivo precision in both densitometers using the same patients and technologists. Precision studies for the Horizon and Discovery models were done by acquiring spine, hip, and forearm bone mineral density twice on 30 participants. The set of 4 scans on each participant (2 on the Discovery, 2 on the Horizon) was acquired by the same technologist using the same scanning mode. The pairs of data were used to calculate the least significant change according to the International Society for Clinical Densitometry guidelines. The significance of the difference between least significant changes was assessed using a Wilcoxon signed-rank test of the difference between the mean square error of the absolute value of the differences between paired measurements on the Discovery (Δ-Discovery) and the mean square error of the absolute value of the differences between paired measurements on the Horizon (Δ-Horizon). At virtually all anatomic sites, there was a nonsignificant trend for the precision to be better for the Horizon than for the Discovery. As more vertebrae were excluded from analysis, the precision deteriorated on both densitometers. The precision between densitometers was almost identical when reporting only 1 vertebral body. (1) There was a nonsignificant trend for greater precision on the new Hologic Horizon compared with the older Discovery model. (2) The difference in precision of the spine bone mineral density between the Horizon and the Discovery models decreases as fewer vertebrae are included. (3) These findings are substantially similar to previously published results which had not controlled as well for confounding from using different

Fluctuations of the flux of energy on the apparent horizon

NASA Astrophysics Data System (ADS)

Mimoso, José P.; Pavón, Diego

2018-05-01

Adopting the Landau-Lifshiftz method of classical fluctuations, we determine the statistical average strength of the fluctuations of the energy flux on the apparent horizon of a homogeneous and isotropic universe described by Einstein gravity. We find that the fluctuations increase with the temperature of the horizon and decrease with its area, in accordance with the features of systems where gravity can be neglected. We further find, on the one hand, that the fluctuations vanish in the cosmological constant dominated de Sitter expansion and, on the other hand, that the domination of phantom fields is excluded. The reasonableness of the results we have obtained lend support to the view that the Universe behaves as a normal thermodynamic system.

75 FR 29397 - National Commission on the BP Deepwater Horizon Oil Spill and Offshore Drilling

Federal Register 2010, 2011, 2012, 2013, 2014

2010-05-26

... National Commission on the BP Deepwater Horizon Oil Spill and Offshore Drilling By the authority vested in... Deepwater Horizon Oil Spill and Offshore Drilling (the ``Commission''). Sec. 2. Membership. (a) The... impact of, oil spills associated with offshore drilling, taking into consideration the environmental...

Flexible Wing Base Micro Aerial Vehicles: Towards Flight Autonomy: Vision-Based Horizon Detection for Micro Air Vehicles

NASA Technical Reports Server (NTRS)

Nechyba, Michael C.; Ettinger, Scott M.; Ifju, Peter G.; Wazak, Martin

2002-01-01

Recently substantial progress has been made towards design building and testifying remotely piloted Micro Air Vehicles (MAVs). This progress in overcoming the aerodynamic obstacles to flight at very small scales has, unfortunately, not been matched by similar progress in autonomous MAV flight. Thus, we propose a robust, vision-based horizon detection algorithm as the first step towards autonomous MAVs. In this paper, we first motivate the use of computer vision for the horizon detection task by examining the flight of birds (biological MAVs) and considering other practical factors. We then describe our vision-based horizon detection algorithm, which has been demonstrated at 30 Hz with over 99.9% correct horizon identification, over terrain that includes roads, buildings large and small, meadows, wooded areas, and a lake. We conclude with some sample horizon detection results and preview a companion paper, where the work discussed here forms the core of a complete autonomous flight stability system.

Correlation based networks of equity returns sampled at different time horizons

NASA Astrophysics Data System (ADS)

Tumminello, M.; di Matteo, T.; Aste, T.; Mantegna, R. N.

2007-01-01

We investigate the planar maximally filtered graphs of the portfolio of the 300 most capitalized stocks traded at the New York Stock Exchange during the time period 2001 2003. Topological properties such as the average length of shortest paths, the betweenness and the degree are computed on different planar maximally filtered graphs generated by sampling the returns at different time horizons ranging from 5 min up to one trading day. This analysis confirms that the selected stocks compose a hierarchical system progressively structuring as the sampling time horizon increases. Finally, a cluster formation, associated to economic sectors, is quantitatively investigated.

Validity in work-based assessment: expanding our horizons.

PubMed

Govaerts, Marjan; van der Vleuten, Cees P M

2013-12-01

Although work-based assessments (WBA) may come closest to assessing habitual performance, their use for summative purposes is not undisputed. Most criticism of WBA stems from approaches to validity consistent with the quantitative psychometric framework. However, there is increasing research evidence that indicates that the assumptions underlying the predictive, deterministic framework of psychometrics may no longer hold. In this discussion paper we argue that meaningfulness and appropriateness of current validity evidence can be called into question and that we need alternative strategies to assessment and validity inquiry that build on current theories of learning and performance in complex and dynamic workplace settings. Drawing from research in various professional fields we outline key issues within the mechanisms of learning, competence and performance in the context of complex social environments and illustrate their relevance to WBA. In reviewing recent socio-cultural learning theory and research on performance and performance interpretations in work settings, we demonstrate that learning, competence (as inferred from performance) as well as performance interpretations are to be seen as inherently contextualised, and can only be under-stood 'in situ'. Assessment in the context of work settings may, therefore, be more usefully viewed as a socially situated interpretive act. We propose constructivist-interpretivist approaches towards WBA in order to capture and understand contextualised learning and performance in work settings. Theoretical assumptions underlying interpretivist assessment approaches call for a validity theory that provides the theoretical framework and conceptual tools to guide the validation process in the qualitative assessment inquiry. Basic principles of rigour specific to qualitative research have been established, and they can and should be used to determine validity in interpretivist assessment approaches. If used properly, these strategies generate trustworthy evidence that is needed to develop the validity argument in WBA, allowing for in-depth and meaningful information about professional competence. © 2013 John Wiley & Sons Ltd.

Conference Offers Girls Opportunity to Expand Career Horizons

Science.gov Websites

math, science, technology and non-traditional occupations. The conference will take place Saturday of computers, math, engineering, natural sciences, medical sciences, public service and the

Blog Revolution: Expanding Classroom Horizons with Web Logs

ERIC Educational Resources Information Center

Richardson, Will

2005-01-01

Blogs are not a passing fad as a new blog is created every second. There are more than 900,000 blog posts a day. Blogs are one of many new disruptive technologies that are transforming the world. They are creating a richer, more dynamic, more interactive Web where participation is the rule rather than the exception. Classrooms and schools are…

Diversity in emergency medicine education: expanding the horizon.

PubMed

Bowman, Steven H; Moreno-Walton, Lisa; Ezenkwele, Ugo A; Heron, Sheryl L

2011-10-01

An emergency medicine (EM)-based curriculum on diversity, inclusion, and cultural competency can also serve as a mechanism to introduce topics on health care disparities. Although the objectives of such curricula and the potential benefits to EM trainees are apparent, there are relatively few resources available for EM program directors to use to develop these specialized curricula. The object of this article is to 1) broadly discuss the current state of curricula of diversity, inclusion, and cultural competency in EM training programs; 2) identify tools and disseminate strategies to embed issues of disparities in health care in the creation of the curriculum; and 3) provide resources for program directors to develop their own curricula. A group of EM program directors with an interest in cultural competency distributed a preworkshop survey through the Council of Emergency Medicine Residency Directors (CORD) e-mail list to EM program directors to assess the current state of diversity and cultural competency training in EM programs. Approximately 50 members attended a workshop during the 2011 CORD Academic Assembly as part of the Best Practices track, where the results of the survey were disseminated and discussed. In addition to the objectives listed above, the presenters reviewed the literature regarding the rationale for a cultural competency curriculum and its relationship to addressing health care disparities, the relationship to unconscious physician bias, and the Tool for Assessing Cultural Competence Training (TACCT) model for curriculum development. © 2011 by the Society for Academic Emergency Medicine.

Sociology of Sport: Expanding Horizons in the Subdiscipline

ERIC Educational Resources Information Center

Harris, Janet C.

2006-01-01

Sociology of sport began to take shape as a subdiscipline in the mid-1960s, and the quotes presented in the first part of this article provide a useful orientation to this formative period and to some of the most important developments in methodologies, theoretical frameworks, and topics of study that have occurred since then. This article offers…

Expanding Horizons in Commercial Recreation for Disabled People.

ERIC Educational Resources Information Center

Nesbitt, John A.

Based on a presentation given at the 1974 National Conference on Commercial Recreation for Disabled People, the paper examines the role of commercial recreation in the lives of the handicapped. Examples of commercial recreation enterprises are listed for equipment, goods and products; recreation centers, services, and schools; entertainment;…

Expanding Horizons: Pacesetters in Adult Education for Work

ERIC Educational Resources Information Center

Chisman, Forrest P.

2009-01-01

The publication is based on the "Adult Readiness Roundtable" Project co-sponsored by CAAL and the National Center on Education and the Economy on April 6-7, 2009. It is not a transcript of the Roundtable discussion; instead it reports on a two-day discussion meeting among a group of exemplary adult-education-for-work programs from around the…

Louisiana Deepwater Horizon Natural Resource Damage Assessment (NRDA)

Science.gov Websites

Contact Us How We Restore Planning Damage Assessment Projects Near You Strategic Frameworks Monitoring and Natural Resource Damage Assessment (NRDA) Public Meeting Louisiana Deepwater Horizon Natural Resource Damage Assessment (NRDA) Public Meeting share Posted on November 15, 2010 | Assessment and Early

Possible Evidence for an Event Horizon in Cyg XR-1

NASA Technical Reports Server (NTRS)

Dolan, Joseph F.; Fisher, Richard R. (Technical Monitor)

2001-01-01

The X-ray emitting component in the Cyg XR-1/HDE226868 system is a leading candidate for identification as a stellar-mass sized black hole. The positive identification of a black hole as predicted by general relativity requires the detection of an event horizon surrounding the point singularity. One signature of such an event horizon would be the existence of dying pulse trains emitted by material spiraling into the event horizon from the last stable orbit around the black hole. We observed the Cyg XR-1 system at three different epochs in a 1400 - 3000 A bandpass with 0.1 ms time resolution using the Hubble Space Telescope's High Speed Photometer. Repeated excursions of the detected flux by more than three standard deviations above the mean are present in the UV flux with FWHM 1 - 10 ms. If any of these excursions are pulses of radiation produced in the system (and not just stochastic variability associated with the Poisson distribution of detected photon arrival times), then this short a timescale requires that the pulses originate in the accretion disk around Cyg XR-1. Two series of pulses with characteristics similar to those expected from dying pulse trains were detected in three hours of observation.

Volatile Transport Implications from the New Horizons Flyby of Pluto

NASA Astrophysics Data System (ADS)

Young, Leslie; Grundy, William M.; Binzel, RIchard P.; Earle, Alissa M.; Linscott, Ivan R.; Hinson, David P.; Zangari, Amanda M.; McKinnon, William B.; Stern, S. Alan; Weaver, Harold A.; Olkin, Catherine B.; Ennico, Kimberly; Gladstone, G. Randall; Summers, Michael E.; Moore, Jeffrey M.; Spencer, John R.

2015-11-01

The New Horizons flyby of Pluto has revealed a striking range of terrains, from the very bright region informally named Sputnik Planum, to very dark regions such as the informally named Cthulhu Regio. Such a variety was beyond the scope of recent models of Pluto's seasonal volatile cycle (Young 2013, ApJL 766, L22; Hansen, Paige and Young 2015, Icarus 246, 183), which assumed globally uniform substrate albedos. The "Exchange with Pressure Plateau (EPP)" class of models in Young (2013) and the favored runs from Hansen et al (2015) had long periods of exchange of volatiles between northern and southern hemispheres. In these models, the equators were largely devoid of volatiles; even though the equatorial latitudes received less insolation than the poles over a Pluto year, they were never the coldest place on the icy world. New models that include a variety of substrate albedos can investigate questions such as whether Sputnik Planum has an albedo that is high enough to act as a local cold trap for much of Pluto's year. We will present the implications of this and other assumption-busting revelations from the New Horizons flyby. This work was supported by NASA’s New Horizons project.

Functionalized expanded porphyrins

DOEpatents

Sessler, Jonathan L; Pantos, Patricia J

2013-11-12

Disclosed are functionalized expanded porphyrins that can be used as spectrometric sensors for high-valent actinide cations. The disclosed functionalized expanded porphyrins have the advantage over unfunctionalized systems in that they can be immobilized via covalent attachment to a solid support comprising an inorganic or organic polymer or other common substrates. Substrates comprising the disclosed functionalized expanded porphyrins are also disclosed. Further, disclosed are methods of making the disclosed compounds (immobilized and free), methods of using them as sensors to detect high valent actinides, devices that comprise the disclosed compounds, and kits.

New insights into microbial responses to oil spills from the Deepwater Horizon incident

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mason, O.U.; Hazen, T.C.

2011-06-15

On April 20, 2010, a catastrophic eruption of methane caused the Deepwater Horizon exploratory drill rig drilling the Macondo Well in Mississippi Canyon Block 252 (MC252) to explode. The Deepwater Horizon oil spill was unprecendeted for several reasons: the volume of oil released; the spill duration; the well depth; the distance from the shore-line (77 km or about 50 miles); the type of oil (light crude); and the injection of dispersant directly at the wellhead. This study clearly demonstrated that there was a profound and significant response by certain members of the in situ microbial community in the deep-sea inmore » the Gulf of Mexico. In particular putative hydrocarbon degrading Bacteria appeared to bloom in response to the Deepwater Horizon oil spill, even though the temperature at these depths is never >5 C. As the plume aged the shifts in the microbial community on a temporal scale suggested that different, yet metabolically important members of the community were able to respond to a myriad of plume constituents, e.g. shifting from propane/ethane to alkanes and finally to methane. Thus, the biodegradation of hydrocarbons in the plume by Bacteria was a highly significant process in the natural attenuation of many compounds released during the Deepwater Horizon oil spill.« less

Ecological Impacts during the Deepwater Horizon Oil Spill

EPA Science Inventory

The Deepwater Horizon (DWH) oil spill was the largest spill and response effort in United States history. Nearly 800 million L of oil was spilled in the Gulf of Mexico, and nearly 7 million L of chemical dispersants were applied in at the ocean surface and subsea1. The DWH spill ...

Knowledge Concerning the Mathematical Horizon: A Close View

ERIC Educational Resources Information Center

Guberman, Raisa; Gorev, Dvora

2015-01-01

The main objective of this study is to identify components of teachers' mathematical knowledge for teaching, associated with the knowledge of mathematical horizon (KMH) in order to describe this type of knowledge from the viewpoint of elementary school mathematics teachers. The research population of this study consisted of 118 elementary school…

Survey of New Horizons International Music Association Musicians

ERIC Educational Resources Information Center

Coffman, Don

2009-01-01

This study analysed survey responses from 1652 New Horizons International Music Association (NHIMA) musicians in the United States and Canada to better understand older adults' experiences in making music. The purpose of this study was threefold: (a) ascertain the extent of NHIMA musicians' musical backgrounds and their current involvement in…

The response of the Seasat and Magsat infrared horizon scanners to cold clouds

NASA Technical Reports Server (NTRS)

Bilanow, S.; Phenneger, M.

1980-01-01

Cold clouds over the Earth are shown to be the principal cause of pitch and roll measurement noise in flight data from the infrared horizon scanners onboard Seasat and Magsat. The observed effects of clouds on the fixed threshold horizon detection logic of the Magsat scanner and on the variable threshold detection logic of the Seasat scanner are discussed. National Oceanic and Atmospheric Administration (NOAA) Earth photographs marked with the scanner ground trace clearly confirm the relationship between measurement errors and Earth clouds. A one to one correspondence can be seen between excursion in the pitch and roll data and cloud crossings. The characteristics of the cloud-induced noise are discussed, and the response of the satellite control systems to the cloud errors is described. Changes to the horizon scanner designs that would reduce the effects of clouds are noted.

75 FR 47584 - National Commission on the BP Deepwater Horizon Oil Spill and Offshore Drilling

Federal Register 2010, 2011, 2012, 2013, 2014

2010-08-06

... DEPARTMENT OF ENERGY National Commission on the BP Deepwater Horizon Oil Spill and Offshore...: This notice announces an open meeting for the National Commission on the BP Deepwater Horizon Oil Spill... in the Federal Register. The Charter of the Commission can be found at: http://www.OilSpillCommission...

75 FR 56526 - National Commission on the BP Deepwater Horizon Oil Spill and Offshore Drilling

Federal Register 2010, 2011, 2012, 2013, 2014

2010-09-16

... DEPARTMENT OF ENERGY National Commission on the BP Deepwater Horizon Oil Spill and Offshore...: This notice announces an open meeting of the National Commission on the BP Deepwater Horizon Oil Spill... in the Federal Register. The Charter of the Commission can be found at: http://www.OilSpillCommission...

Circular geodesic of Bardeen and Ayon-Beato-Garcia regular black-hole and no-horizon spacetimes

NASA Astrophysics Data System (ADS)

Stuchlík, Zdeněk; Schee, Jan

2015-12-01

In this paper, we study circular geodesic motion of test particles and photons in the Bardeen and Ayon-Beato-Garcia (ABG) geometry describing spherically symmetric regular black-hole or no-horizon spacetimes. While the Bardeen geometry is not exact solution of Einstein's equations, the ABG spacetime is related to self-gravitating charged sources governed by Einstein's gravity and nonlinear electrodynamics. They both are characterized by the mass parameter m and the charge parameter g. We demonstrate that in similarity to the Reissner-Nordstrom (RN) naked singularity spacetimes an antigravity static sphere should exist in all the no-horizon Bardeen and ABG solutions that can be surrounded by a Keplerian accretion disc. However, contrary to the RN naked singularity spacetimes, the ABG no-horizon spacetimes with parameter g/m > 2 can contain also an additional inner Keplerian disc hidden under the static antigravity sphere. Properties of the geodesic structure are reflected by simple observationally relevant optical phenomena. We give silhouette of the regular black-hole and no-horizon spacetimes, and profiled spectral lines generated by Keplerian rings radiating at a fixed frequency and located in strong gravity region at or nearby the marginally stable circular geodesics. We demonstrate that the profiled spectral lines related to the regular black-holes are qualitatively similar to those of the Schwarzschild black-holes, giving only small quantitative differences. On the other hand, the regular no-horizon spacetimes give clear qualitative signatures of their presence while compared to the Schwarschild spacetimes. Moreover, it is possible to distinguish the Bardeen and ABG no-horizon spacetimes, if the inclination angle to the observer is known.

Time to Grow: Year Two Report on ExpandED Schools. A TASC Report

ERIC Educational Resources Information Center

Traill, Saskia; Brohawn, Katie

2014-01-01

An analysis of data from the second year of The After-School Corporation's (TASC's) national demonstration of an expanded school day for elementary and middle school students shows that ExpandED Schools improved school culture, decreased rates of students' chronic absenteeism and helped students develop positive learning habits and attitudes.…

Gulf coast ports surrounding the Deepwater Horizon oil spill

DOT National Transportation Integrated Search

2010-06-01

This fact sheet provides a snapshot of two major seaports : (New Orleans, LA, and Mobile, AL) and summary tables of : other Gulf coast seaports close to the Deepwater Horizon mobile : offshore drilling unit (MODU) explosion and oil spill. New : Orlea...

Nap Time for New Horizons: NASA Spacecraft Enters Hibernation

NASA Image and Video Library

2017-04-11

This is an overhead view of NASA's New Horizons full trajectory; the spacecraft has entered a hibernation phase on April 7 that will last until early September. The full article is available at https://photojournal.jpl.nasa.gov/catalog/PIA21589

Reduced Solar Wind Speeds at New Horizons Beyond 30 AU

NASA Astrophysics Data System (ADS)

Elliott, H. A.; McComas, D. J.; Zirnstein, E.; Delamere, P. A.; Bagenal, F.; Stern, A.; Weaver, H. A., Jr.; Young, L. A.; Ennico Smith, K.; Olkin, C.

2017-12-01

Prior comparisons between Voyager 2 and IMP 8 observations found the solar wind had clearly decrease by 8% at a distance of 25 AU. Since mid-2016 solar rotation averaged speeds at New Horizons have been elevated relative to speeds observed in 2014 and 2015. However, we find a clear decrease in the New Horizons speeds beyond 30 AU when compared to those of ACE near Earth. At distances between 30-38.5 AU the relative speed reduction is in the 8-11% range. We will further this work by also comparing with available STEREO observations. By including STEREO, we can assess how sensitive the speed comparisons are to longitude separations and determine the appropriate time scale to average over.

Speciation and distribution of cadmium and lead in salinized horizons of antrosols

NASA Astrophysics Data System (ADS)

Bulgariu, D.; Bulgariu, L.; Astefanei, D.

2009-04-01

The utilization of intensive technologies for the vegetable cultivation in glass houses by the administration of high doses of organic fertilizes, the supra-dimensional irrigation and the maintaining of soil at high humidity state, in special in case of vicious drainage have as result the rapid degradation of morphological, chemical and physical characteristics of soils, concretized by: (i) decrease of structural aggregates stability; (ii) more dense packing of soil; (iii) accumulation of easy soluble salts (in special at superior horizons level); (iv) limitation of organic compounds and micro-elements biodisponibility. All these determined a significant reduction of productivity and of exploitation duration of soils from glass houses. These phenomena modified continuously the dynamic of speciation processes and inter-phases distribution, of heavy metals in soils from glass houses, and can determined a non-controlled accumulation of heavy metals, in special as mobile forms with high biodisponibility. Ours studied have been performed using soil profiles drawing from Copou-glass house, Iasi (Romania). Has been followed the modification of distribution for speciation forms of cadmium and lead (two heavy metals with high toxicity degree), between hortic antrosol horizons, and between chemical-mineralogical components of this, with the progressive salinization of superior horizons, in 2007-2008 period. The separation, differentiation and determination of cadmium and lead speciation forms was done by combined solid-liquid sequential extraction (SPE) and extraction in aqueous polymer-inorganic salt two-phase systems (ABS) procedure, presented in some of ours previous studies. After extraction, the total contents of the two heavy metals and fractions from these differential bonded by mineral and organic components of hortic antrosol have been determined by atomic absorption spectrometry. The specific interaction mechanisms of Cd and Pb with organic-mineral components of

String-theoretic breakdown of effective field theory near black hole horizons

NASA Astrophysics Data System (ADS)

Dodelson, Matthew; Silverstein, Eva

2017-09-01

We investigate the validity of the equivalence principle near horizons in string theory, analyzing the breakdown of effective field theory caused by longitudinal string spreading effects. An experiment is set up where a detector is thrown into a black hole a long time after an early infalling string. Light cone gauge calculations, taken at face value, indicate a detectable level of root-mean-square longitudinal spreading of the initial string as measured by the late infaller. This results from the large relative boost between the string and detector in the near-horizon region, which develops automatically despite their modest initial energies outside the black hole and the weak curvature in the geometry. We subject this scenario to basic consistency checks, using these to obtain a relatively conservative criterion for its detectability. In a companion paper, we exhibit longitudinal nonlocality in well-defined gauge-invariant S-matrix calculations, obtaining results consistent with the predicted spreading albeit not in a direct analog of the black hole process. We discuss applications of this effect to the firewall paradox, and estimate the time and distance scales it predicts for new physics near black hole and cosmological horizons.

Interior view, looking northeast in computer room OvertheHorizon Backscatter ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

Interior view, looking northeast in computer room - Over-the-Horizon Backscatter Radar Network, Tulelake Radar Site Receive Sector Five Receiver Building, Unnamed Road West of Double Head Road, Tulelake, Siskiyou County, CA

Interior view, looking south in computer room OvertheHorizon Backscatter ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

Interior view, looking south in computer room - Over-the-Horizon Backscatter Radar Network, Tulelake Radar Site Receive Sector Six Receiver Building, Unnamed Road West of Double Head Road, Tulelake, Siskiyou County, CA

General view looking northnortheast at antenna array OvertheHorizon Backscatter ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

General view looking north-northeast at antenna array - Over-the-Horizon Backscatter Radar Network, Moscow Radar Site Transmit Sector Two Antenna Array, At the end of Steam Road, Moscow, Somerset County, ME

Detail of antenna array, looking northnorthwest OvertheHorizon Backscatter Radar ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

Detail of antenna array, looking north-northwest - Over-the-Horizon Backscatter Radar Network, Tulelake Radar Site Receive Sector Five Antenna Array, Unnamed Road West of Double Head Road, Tulelake, Siskiyou County, CA

General view looking northnortheast at antenna array OvertheHorizon Backscatter ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

General view looking north-northeast at antenna array - Over-the-Horizon Backscatter Radar Network, Moscow Radar Site Transmit Sector One Antenna Array, At the end of Steam Road, Moscow, Somerset County, ME

General view of Antenna Array, looking west OvertheHorizon Backscatter ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

General view of Antenna Array, looking west - Over-the-Horizon Backscatter Radar Network, Tulelake Radar Site Receive Sector Six Antenna Array, Unnamed Road West of Double Head Road, Tulelake, Siskiyou County, CA

Apollo 8 Mission image,Earth and Lunar Horizon

NASA Image and Video Library

1968-12-21

Apollo 8,Earth and Lunar Horizon. Image taken on Revolution 10 during Transearth Injection (TEI). Original Film Magazine was labeled D. Camera Data: 70mm Hasselblad. Lens: 80mm; F-Stop: F/11; Shutter Speed: 1/250 second. Film Type: Kodak SO-3400 Black and White,ASA 40. Flight Date: December 21-27,1968.

Investment horizon heterogeneity and wavelet: Overview and further research directions

NASA Astrophysics Data System (ADS)

Chakrabarty, Anindya; De, Anupam; Gunasekaran, Angappa; Dubey, Rameshwar

2015-07-01

Wavelet based multi-scale analysis of financial time series has attracted much attention, lately, from both the academia and practitioners from all around the world. The unceasing metamorphosis of the discipline of finance from its humble beginning as applied economics to the more sophisticated depiction as applied physics and applied psychology has revolutionized the way we perceive the market and its complexities. One such complexity is the presence of heterogeneous horizon agents in the market. In this context, we have performed a generous review of different aspects of horizon heterogeneity that has been successfully elucidated through the synergy between wavelet theory and finance. The evolution of wavelet has been succinctly delineated to bestow necessary information to the readers who are new to this field. The migration of wavelet into finance and its subsequent branching into different sub-divisions have been sketched. The pertinent literature on the impact of horizon heterogeneity on risk, asset pricing and inter-dependencies of the financial time series are explored. The significant contributions are collated and classified in accordance to their purpose and approach so that potential researcher and practitioners, interested in this subject, can be benefited. Future research possibilities in the direction of "agency cost mitigation" and "synergy between econophysics and behavioral finance in stock market forecasting" are also suggested in the paper.

Retrieving aerosol profiles through horizon shadowing and polarimetry

NASA Astrophysics Data System (ADS)

Videen, G.; Pavlov, A.; Zubko, E.; Konstantinov, O.; Shmirko, K.; Mayor, A.

2017-12-01

We report polarimetric measurements of atmospheric aerosol in evening and morning twilight over Vladivostok, Russia in late winter-early spring of 2017 using a horizon-shadowing technique. The motion of the Sun beneath the horizon changes the altitude of the boundary of the shadowed atmosphere h, making it possible to constrain the altitude of aerosol particles contributing to the polarimetric response. We investigate the degree of linear polarization P in aerosol particles at different altitudes, ranging from 0 km up to 17 km. In two out of four experiments we found significant variations of the polarimetric response (ΔP 10%) with altitude; whereas, in the other measurements, the polarization appeared nearly the same (ΔP 2-3%) throughout the entire range of the studied altitude. Polarization P was measured in the zenith direction with the scattering angle being θ 90°. At such a scattering angle, the polarization is near its maximum value Pmax. Conclusions drawn from polarimetric measurements appear in qualitative accordance with results of remote sensing with a three-wavelength lidar.

Typical event horizons in AdS/CFT

NASA Astrophysics Data System (ADS)

Avery, Steven G.; Lowe, David A.

2016-01-01

We consider the construction of local bulk operators in a black hole background dual to a pure state in conformal field theory. The properties of these operators in a microcanonical ensemble are studied. It has been argued in the literature that typical states in such an ensemble contain firewalls, or otherwise singular horizons. We argue this conclusion can be avoided with a proper definition of the interior operators.

Typical event horizons in AdS/CFT

DOE PAGES

Avery, Steven G.; Lowe, David A.

2016-01-14

We consider the construction of local bulk operators in a black hole background dual to a pure state in conformal field theory. The properties of these operators in a microcanonical ensemble are studied. It has been argued in the literature that typical states in such an ensemble contain firewalls, or otherwise singular horizons. Here, we argue this conclusion can be avoided with a proper definition of the interior operators.

Oblique view to south OvertheHorizon Backscatter Radar Network, Mountain ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

Oblique view to south - Over-the-Horizon Backscatter Radar Network, Mountain Home Air Force Operations Building, On Desert Street at 9th Avenue Mountain Home Air Force Base, Mountain Home, Elmore County, ID

Detail of antenna tower structure, looking northnorthwest OvertheHorizon Backscatter ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

Detail of antenna tower structure, looking north-northwest - Over-the-Horizon Backscatter Radar Network, Tulelake Radar Site Receive Sector Five Antenna Array, Unnamed Road West of Double Head Road, Tulelake, Siskiyou County, CA

Pluto's Extended Atmosphere: New Horizons Alice Lyman-α Imaging

NASA Astrophysics Data System (ADS)

Retherford, Kurt D.; Gladstone, G. Randall; Stern, S. Alan; Weaver, Harold A.; Young, Leslie A.; Ennico, Kimberly A.; Olkin, Cathy B.; Cheng, Andy F.; Greathouse, Thomas K.; Hinson, David P.; Kammer, Joshua A.; Linscott, Ivan R.; Parker, Alex H.; Parker, Joel Wm.; Pryor, Wayne R.; Schindhelm, Eric; Singer, Kelsi N.; Steffl, Andrew J.; Strobel, Darrell F.; Summers, Michael E.; Tsang, Constantine C. C.; Tyler, G. Len; Versteeg, Maarten H.; Woods, William W.; Cunningham, Nathaniel J.; Curdt, Werner

2015-11-01

Pluto's upper atmosphere is expected to extend several planetary radii, proportionally more so than for any planet in our solar system. Atomic hydrogen is readily produced at lower altitudes due to photolysis of methane and transported upward to become an important constituent. The Interplanetary Medium (IPM) provides a natural light source with which to study Pluto's atomic hydrogen atmosphere. While direct solar Lyman-α emissions dominate the signal at 121.6 nm at classical solar system distances, the contribution of diffuse illumination by IPM Lyman-α sky-glow is roughly on par at Pluto (Gladstone et al., Icarus, 2015). Hydrogen atoms in Pluto's upper atmosphere scatter these bright Lyα emission lines, and detailed simulations of the radiative transfer for these photons indicate that Pluto would appear dark against the IPM Lyα background. The Pluto-Alice UV imaging spectrograph on New Horizons conducted several observations of Pluto during the encounter to search for airglow emissions, characterize its UV reflectance spectra, and to measure the radial distribution of IPM Lyα near the disk. Our early results suggest that these model predictions for the darkening of IPM Lyα with decreasing altitude being measureable by Pluto-Alice were correct. We'll report our progress toward extracting H and CH4 density profiles in Pluto's upper atmosphere through comparisons of these data with detailed radiative transfer modeling. These New Horizons findings will have important implications for determining the extent of Pluto's atmosphere and related constraints to high-altitude vertical temperature structure and atmospheric escape.This work was supported by NASA's New Horizons project.

Comparison of self-expandable and balloon-expanding stents for hybrid ductal stenting in hypoplastic left heart complex.

PubMed

Goreczny, Sebastian; Qureshi, Shakeel A; Rosenthal, Eric; Krasemann, Thomas; Nassar, Mohamed S; Anderson, David R; Morgan, Gareth J

2017-07-01

We aimed to compare the procedural and mid-term performance of a specifically designed self-expanding stent with balloon-expandable stents in patients undergoing hybrid palliation for hypoplastic left heart syndrome and its variants. The lack of specifically designed stents has led to off-label use of coronary, biliary, or peripheral stents in the neonatal ductus arteriosus. Recently, a self-expanding stent, specifically designed for use in hypoplastic left heart syndrome, has become available. We carried out a retrospective cohort comparison of 69 neonates who underwent hybrid ductal stenting with balloon-expandable and self-expanding stents from December, 2005 to July, 2014. In total, 43 balloon-expandable stents were implanted in 41 neonates and more recently 47 self-expanding stents in 28 neonates. In the balloon-expandable stents group, stent-related complications occurred in nine patients (22%), compared with one patient in the self-expanding stent group (4%). During follow-up, percutaneous re-intervention related to the ductal stent was performed in five patients (17%) in the balloon-expandable stent group and seven patients (28%) in self-expanding stents group. Hybrid ductal stenting with self-expanding stents produced favourable results when compared with the results obtained with balloon-expandable stents. Immediate additional interventions and follow-up re-interventions were similar in both groups with complications more common in those with balloon-expandable stents.

Visual orientation performances of desert ants (Cataglyphis bicolor) toward astromenotactic directions and horizon landmarks

NASA Technical Reports Server (NTRS)

Wehner, R.

1972-01-01

Experimental data, on the visual orientation of desert ants toward astromenotactic courses and horizon landmarks involving the cooperation of different direction finding systems, are given. Attempts were made to: (1) determine if the ants choose a compromise direction between astromenotactic angles and the direction toward horizon landmarks when both angles compete with each other or whether they decide alternatively; (2) analyze adaptations of the visual system to the special demands of direction finding by astromenotactic orientation or pattern recognition; and (3) determine parameters of visual learning behavior. Results show separate orientation mechanisms are responsible for the orientation of the ant toward astromenotactic angles and horizon landmarks. If both systems compete with each other, the ants switch over from one system to the other and do not perform a compromise direction.

V.C.3 Technology Validation : Fuel Cell Bus Evaluations

DOT National Transportation Integrated Search

2005-01-06

Based on the results of this analysis and the response from the project partners, the SunLine demonstration was deemed to be a success. Although it was a prototype (or pre-commercial) vehicle, the ThunderPower bus operated in revenue service at a rel...

Influences upon the lead isotopic composition of organic and mineral horizons in soil profiles from the National Soil Inventory of Scotland (2007-09).

PubMed

Farmer, John G; Graham, Margaret C; Eades, Lorna J; Lilly, Allan; Bacon, Jeffrey R

2016-02-15

Some 644 individual soil horizons from 169 sites in Scotland were analyzed for Pb concentration and isotopic composition. There were three scenarios: (i) 36 sites where both top and bottom (i.e. lowest sampled) soil horizons were classified as organic in nature, (ii) 67 with an organic top but mineral bottom soil horizon, and (iii) 66 where both top and bottom soil horizons were mineral. Lead concentrations were greater in the top horizon relative to the bottom horizon in all but a few cases. The top horizon (206)Pb/(207)Pb ratio was lesser (outside analytical error) than the corresponding bottom horizon (206)Pb/(207)Pb ratio at (i) 64%, (ii) 94% and (iii) 73% of sites, and greater at only (i) 8%, (ii) 3% and (iii) 8% of sites. A plot of (208)Pb/(207)Pb vs. (208)Pb/(206)Pb ratios showed that the Pb in organic top (i, ii) and bottom (i) horizons was consistent with atmospherically deposited Pb of anthropogenic origin. The (206)Pb/(207)Pb ratio of the organic top horizon in (ii) was unrelated to the (206)Pb/(207)Pb ratio of the mineral bottom horizon as demonstrated by the geographical variation in the negative shift in the ratio, a result of differences in the mineral horizon values arising from the greater influence of radiogenic Pb in the north. In (iii), the lesser values of the (206)Pb/(207)Pb ratio for the mineral top horizon relative to the mineral bottom horizon were consistent with the presence of anthropogenic Pb, in addition to indigenous Pb, in the former. Mean anthropogenic Pb inventories of 1.5 and 4.5 g m(-2) were obtained for the northern and southern halves of Scotland, respectively, consistent with long-range atmospheric transport of anthropogenic Pb (mean (206)Pb/(207)Pb ratio~1.16). For cultivated agricultural soils (Ap), this corresponded to about half of the total Pb inventory in the top 30 cm of the soil column. Copyright © 2015 Elsevier B.V. All rights reserved.

75 FR 37712 - Temporary Suspension of Certain Oil Spill Response Time Requirements To Support Deepwater Horizon...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-06-30

.... (Memorandum from Rear Admiral J.A. Watson, FOSC BP Deepwater Horizon Oil Spill, to National Incident Command... Temporary Suspension of Certain Oil Spill Response Time Requirements To Support Deepwater Horizon Oil Spill... Protection Agency (EPA) temporary interim rule will suspend oil spill response time requirements, and certain...

New characterization aspects of carbonate accumulation horizons in Chalky Champagne (NE of the Paris Basin, France)

NASA Astrophysics Data System (ADS)

Linoir, Damien; Thomachot-Schneider, Céline; Gommeaux, Maxime; Fronteau, Gilles; Barbin, Vincent

2016-05-01

The soil profiles of the Champagne area (NE of Paris Basin, France) occasionally show carbonate accumulation horizons (CAHs). From the top to the bottom, these soil profiles include a rendic leptosol horizon, a Quaternary cryoturbated paleosol (QCP), and a chalky substratum. The CAHs are located in the top part of the QCP. This study is aimed at highlighting the specific characteristics of CAHs compared to other soil profile horizons using geophysics, geochemistry, micromorphology, and mercury injection porosimetry. It is the first essential step for understanding the impact of CAHs on water transfers into the Champagne soil profiles. Our analyses show that Champagne CAHs are not systematically characterized by a typical induration unlike generally put forward in the regional literature. They are more porous and heterogeneous than their parent material (QCP). Carbonate accumulation horizons are also characterized by singular colorimetric parameters that are linked to their geochemical specific content, even if they bear a signature of the initial QCP before the pedogenic modification.

Use of microcomputer in mapping depth of stratigraphic horizons in National Petroleum Reserve in Alaska

USGS Publications Warehouse

Payne, Thomas G.

1982-01-01

REGIONAL MAPPER is a menu-driven system in the BASIC language for computing and plotting (1) time, depth, and average velocity to geologic horizons, (2) interval time, thickness, and interval velocity of stratigraphic intervals, and (3) subcropping and onlapping intervals at unconformities. The system consists of three programs: FILER, TRAVERSER, and PLOTTER. A control point is a shot point with velocity analysis or a shot point at or near a well with velocity check-shot survey. Reflection time to and code number of seismic horizons are filed by digitizing tablet from record sections. TRAVERSER starts at a point of geologic control and, in traversing to another, parallels seismic events, records loss of horizons by onlap and truncation, and stores reflection time for geologic horizons at traversed shot points. TRAVERSER is basically a phantoming procedure. Permafrost thickness and velocity variations, buried canyons with low-velocity fill, and error in seismically derived velocity cause velocity anomalies that complicate depth mapping. Two depths to the top of the pebble is based shale are computed for each control point. One depth, designated Zs on seismically derived velocity. The other (Zw) is based on interval velocity interpolated linearly between wells and multiplied by interval time (isochron) to give interval thickness. Z w is computed for all geologic horizons by downward summation of interval thickness. Unknown true depth (Z) to the pebble shale may be expressed as Z = Zs + es and Z = Zw + ew where the e terms represent error. Equating the two expressions gives the depth difference D = Zs + Zw = ew + es A plot of D for the top of the pebble shale is readily contourable but smoothing is required to produce a reasonably simple surface. Seismically derived velocity used in computing Zs includes the effect of velocity anomalies but is subject to some large randomly distributed errors resulting in depth errors (es). Well-derived velocity used in computing Zw

Persistence of 137Cs in the litter layers of forest soil horizons of Mount IDA/Kazdagi, Turkey.

PubMed

Karadeniz, Özlem; Karakurt, Hidayet; Çakır, Rukiye; Çoban, Fatih; Büyükok, Emir; Akal, Cüneyt

2015-01-01

In 2010-2012, an extensive study was performed in forest sites of Mount IDA (Kazdagi)/Edremit 26 years after the Chernobyl accident. The (137)Cs activity concentrations were determined by gamma-ray spectrometry in the forest soil layers (OL, OF + OH and A horizons) separately. Based on 341 surface soil samples and 118 soil profiles, activity concentrations of (137)Cs in OL horizons varied between 0.25 ± 0.14 and 70 ± 1 Bq kg(-1), while the ranges of (137)Cs activity concentrations in OF + OH and A horizons were 13 ± 1-555 ± 3 Bq kg(-1) and 2 ± 1-253 ± 2 Bq kg(-1), respectively. Cesium-137 deposition in the study area was estimated to be in the range of 1-39 kBq m(-2) and a linear relationship between the deposition of (137)Cs and the altitude was observed. The distributions of (137)Cs activities in OL, OF + OH and A horizons throughout the region were mapped in detail. The highest (137)Cs activities were found in OF + OH horizons, with markedly lower (137)Cs activity in mineral horizons of soil profiles. It is observed that (137)Cs content of humus layer increases with the thickness of the humus layer for coniferous forest sites. The (137)Cs activity concentrations were higher than the recommended screening limits (150 Bq kg(-1)) at some of the investigated areas. The current activity concentration of top soil layers indicates that over many years since the initial deposition, (137)Cs activity is keeping still high in the organic horizons. Copyright © 2014 Elsevier Ltd. All rights reserved.

Seismic Characterization and Continuity Analysis of Gas Hydrate Horizons Near the Mallik Research Wells, Mackenzie Delta, Canada

NASA Astrophysics Data System (ADS)

Bellefleur, G.; Riedel, M.; Brent, T.

2005-12-01

Gas hydrate deposits in arctic environment generally lack the BSR signature diagnostic of their presence in marine seismic data. The absence of the BSR signature complicates the estimation of the resources within or below the permafrost and the determination of their potential impact on future energy supplies, geohazard and climate change. We present results from a detailed seismic characterization of three gas hydrate horizons (A, B and C) intersected below the permafrost in five wells of the Mallik gas hydrate field located in the Mackenzie delta (Northwest Territories, Canada). The detailed seismic characterization included attribute analyses, synthetic modeling and acoustic impedance inversion and allowed estimation of the lateral continuity of the three horizons in the vicinity of the wells. Vertical Seismic Profiling (VSP) data, 3D and 2D industry seismic data and the 5L/2L-38 geophysical logs (density, P-wave sonic velocity) were used for this study. Synthetic modeling using the sonic and density logs reveals that the base of the lower gas hydrate horizons B and C can be identified on the industry 3D and 2D seismic sections as prominent isolated reflections. The uppermost gas hydrate occurrence (horizon A) and potentially other additional smaller-scale layers are identified only on the higher-resolution VSP data. The 3D industry seismic data set processed to preserve the relative true-amplitudes was used for attribute calculations and acoustic impedance inversion. The attribute maps defined areas of continuous reflectivity for horizons B and C and structural features disrupting them. Results from impedance inversion indicate that such continuous reflectivity around the wells is most likely attributable to gas hydrates. The middle gas hydrate occurrence (horizon B) covers an area of approximately 25 000m2. Horizon C, which marks the base of gas hydrate occurrence zone, extends over a larger area of approximately 120 000m2.

Ecological Impacts During the Deepwater Horizon Oil Spill Response

EPA Science Inventory

The Deepwater Horizon (DWH) oil spill was the largest environmental disaster and response effort in U.S. history, with nearly 800 million liters of crude oil spilled. Vast areas of the Gulf of Mexico were contaminated with oil, including deep-ocean communities and over 1,600 kilo...

View to the northeast of the antenna array OvertheHorizon ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

View to the northeast of the antenna array - Over-the-Horizon Backscatter Radar Network, Christmas Valley Radar Site Transmit Sector Four Antenna Array, On unnamed road west of Lost Forest Road, Christmas Valley, Lake County, OR

View to the east of the Antenna Array OvertheHorizon ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

View to the east of the Antenna Array - Over-the-Horizon Backscatter Radar Network, Christmas Valley Radar Site Transmit Sector Six Antenna Array, On unnamed road west of Lost Forest Road, Christmas Valley, Lake County, OR

View to the northeast of the Sounder Antenna OvertheHorizon ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

View to the northeast of the Sounder Antenna - Over-the-Horizon Backscatter Radar Network, Christmas Valley Radar Site Transmit Sector Five Sounder Antennas, On unnamed road west of Lost Forest Road, Christmas Valley, Lake County, OR

75 FR 39518 - National Commission on the BP Deepwater Horizon Oil Spill and Offshore Drilling; Correction

Federal Register 2010, 2011, 2012, 2013, 2014

2010-07-09

... DEPARTMENT OF ENERGY National Commission on the BP Deepwater Horizon Oil Spill and Offshore... an open meeting on July 12 and 13, 2010, of the National Commission on the BP Deepwater Horizon Oil Spill and Offshore Drilling, (75 FR 37783). This document makes several corrections to that notice. FOR...

Predicting mortality over different time horizons: which data elements are needed?

PubMed

Goldstein, Benjamin A; Pencina, Michael J; Montez-Rath, Maria E; Winkelmayer, Wolfgang C

2017-01-01

Electronic health records (EHRs) are a resource for "big data" analytics, containing a variety of data elements. We investigate how different categories of information contribute to prediction of mortality over different time horizons among patients undergoing hemodialysis treatment. We derived prediction models for mortality over 7 time horizons using EHR data on older patients from a national chain of dialysis clinics linked with administrative data using LASSO (least absolute shrinkage and selection operator) regression. We assessed how different categories of information relate to risk assessment and compared discrete models to time-to-event models. The best predictors used all the available data (c-statistic ranged from 0.72-0.76), with stronger models in the near term. While different variable groups showed different utility, exclusion of any particular group did not lead to a meaningfully different risk assessment. Discrete time models performed better than time-to-event models. Different variable groups were predictive over different time horizons, with vital signs most predictive for near-term mortality and demographic and comorbidities more important in long-term mortality. © The Author 2016. Published by Oxford University Press on behalf of the American Medical Informatics Association. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Renormalized stress-energy tensor near the horizon of a slowly evolving, rotating black hole

DOE Office of Scientific and Technical Information (OSTI.GOV)

Frolov, V.P.; Thorne, K.S.

1989-04-15

The renormalized expectation value of the stress-energy tensor /sup ren/ of a quantum field in an arbitrary quantum state near the future horizon of a rotating (Kerr) black hole is derived in two very different ways: One derivation (restricted for simplicity to a massless scalar field) makes use of traditional techniques of quantum field theory in curved spacetime, augmented by a variant of the ''eta formalism'' for handling superradiant modes. The other derivation (valid for any quantum field) uses the equivalence principle to infer, from /sup ren/ in flat spacetime, what must be /sup ren/ near the hole's horizon. Themore » two derivations give the same result: a result in accord with a previous conjecture by Zurek and Thorne: /sup ren/, in any quantum state, is equal to that, /sup ZAMO/, which zero-angular-momentum observers (ZAMO's) would compute from their own physical measurements near the horizon, plus a vacuum-polarization contribution T/sub ..mu..//sub ..nu..//sup vac pol/, which is the negative of the stress-energy of a rigidly rotating thermal reservoir with angular velocity equal to that of the horizon ..cap omega../sub H/, and (red-shifted) temperature equal to that of the Hawking temperature T/sub H/.« less

View to the northeast of the southwest elevation OvertheHorizon ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

View to the northeast of the southwest elevation - Over-the-Horizon Backscatter Radar Network, Mountain Home Air Force Operations Building, On Desert Street at 9th Avenue Mountain Home Air Force Base, Mountain Home, Elmore County, ID

View to the northwest of the southeast elevation OvertheHorizon ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

View to the northwest of the southeast elevation - Over-the-Horizon Backscatter Radar Network, Mountain Home Air Force Operations Building, On Desert Street at 9th Avenue Mountain Home Air Force Base, Mountain Home, Elmore County, ID

View to the eastnortheast of the Sounder Antenna OvertheHorizon ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

View to the east-northeast of the Sounder Antenna - Over-the-Horizon Backscatter Radar Network, Christmas Valley Radar Site Transmit Sector Five Sounder Antennas, On unnamed road west of Lost Forest Road, Christmas Valley, Lake County, OR

View to the eastnortheast of the Antenna Array OvertheHorizon ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

View to the east-northeast of the Antenna Array - Over-the-Horizon Backscatter Radar Network, Christmas Valley Radar Site Transmit Sector Six Antenna Array, On unnamed road west of Lost Forest Road, Christmas Valley, Lake County, OR

Supporting Students' Pedagogical Working Life Horizon in Higher Education

ERIC Educational Resources Information Center

Penttinen, Leena; Skaniakos, Terhi; Lairio, Marjatta

2013-01-01

In this article, we introduce a model of a pedagogical working life horizon. It encompasses questions posed by individual students concerning their future and incorporates the idea of a working life orientation to the pedagogical possibilities within education. Working life orientation consists of three elements: individual relationship, knowledge…

The Attitude Control System for the Wilkinson Microwave Anisotropy Probe

NASA Technical Reports Server (NTRS)

Markley, F. Landis; Andrews, Stephen F.; ODonnell, James R., Jr.; Ward, David K.

2003-01-01

The Wilkinson Microwave Anisotropy Probe mission produces a map of the cosmic microwave background radiation over the entire celestial sphere by executing a fast spin and a slow precession of its spin axis about the Sun line to obtain a highly interconnected set of measurements. The spacecraft attitude is sensed and controlled using an inertial reference unit, two star trackers, a digital sun sensor, twelve coarse sun sensors, three reaction wheel assemblies, and a propulsion system. Sufficient attitude knowledge is provided to yield instrument pointing to a standard deviation (l sigma) of 1.3 arc-minutes per axis. In addition, the spacecraft acquires and holds the sunline at initial acquisition and in the event of a failure, and slews to the proper orbit adjust orientations and to the proper off-sunline attitude to start the compound spin. This paper presents an overview of the design of the attitude control system to carry out this mission and presents some early flight experience.

Multiple microtektite horizons in upper Eocene marine sediments: No evidence for mass extinctions

USGS Publications Warehouse

Keller, G.; D'Hondt, Steven L.; Vallier, T.L.

1983-01-01

Microtektites have been recovered from three horizons in eight middle Eocene to middle Oligocene marine sediment sequences. Five of these occurrences are coeval and of latest Eocene age (37.5 to 38.0 million years ago); three are coeval and of early late Eocene age (38.5 to 39.5 million years ago); and three are of middle Oligocene age (31 to 32 million years ago). In addition, rare probable microtektites have been found in sediments with ages of about 36.0 to 36.5 million years. The microtektite horizon at 37.5 to 38.0 million years can be correlated with the North American tektite-strewn field, which has a fission track age (minimum) of 34 to 35 million years and a paleomagnetic age of 37.5 to 38.0 million years. There is no evidence for mass faunal extinctions at any of the microtektite horizons. Many of the distinct faunal changes that occurred in the middle Eocene to middle Oligocene can be related to the formation of the Antarctic ice sheet and the associated cooling phenomena and intensification of bottom currents that led to large-scale dissolution of calcium carbonate and erosion, which created areally extensive hiatuses in the deep-sea sediment records. The occurrence of microtektite horizons of several ages and the lack of evidence for faunal extinctions suggest that the effects of extraterrestrial bolide impacts may be unimportant in the biologic realm during middle Eocene to middle Oligocene time.

Expander for Thin-Wall Tubing

NASA Technical Reports Server (NTRS)

Pessin, R.

1983-01-01

Tool locally expands small-diameter tubes. Tube expander locally expands and deforms tube: Compressive lateral stress induced in elastomeric sleeve by squeezing axially between two metal tool parts. Adaptable to situations in which tube must have small bulge for mechanical support or flow control.

Probing Planckian Corrections at the Horizon Scale with LISA Binaries

NASA Astrophysics Data System (ADS)

Maselli, Andrea; Pani, Paolo; Cardoso, Vitor; Abdelsalhin, Tiziano; Gualtieri, Leonardo; Ferrari, Valeria

2018-02-01

Several quantum-gravity models of compact objects predict microscopic or even Planckian corrections at the horizon scale. We explore the possibility of measuring two model-independent, smoking-gun effects of these corrections in the gravitational waveform of a compact binary, namely, the absence of tidal heating and the presence of tidal deformability. For events detectable by the future space-based interferometer LISA, we show that the effect of tidal heating dominates and allows one to constrain putative corrections down to the Planck scale. The measurement of the tidal Love numbers with LISA is more challenging but, in optimistic scenarios, it allows us to constrain the compactness of a supermassive exotic compact object down to the Planck scale. Our analysis suggests that highly spinning, supermassive binaries at 1-20 Gpc provide unparalleled tests of quantum-gravity effects at the horizon scale.

Probing Planckian Corrections at the Horizon Scale with LISA Binaries.

PubMed

Maselli, Andrea; Pani, Paolo; Cardoso, Vitor; Abdelsalhin, Tiziano; Gualtieri, Leonardo; Ferrari, Valeria

2018-02-23

Several quantum-gravity models of compact objects predict microscopic or even Planckian corrections at the horizon scale. We explore the possibility of measuring two model-independent, smoking-gun effects of these corrections in the gravitational waveform of a compact binary, namely, the absence of tidal heating and the presence of tidal deformability. For events detectable by the future space-based interferometer LISA, we show that the effect of tidal heating dominates and allows one to constrain putative corrections down to the Planck scale. The measurement of the tidal Love numbers with LISA is more challenging but, in optimistic scenarios, it allows us to constrain the compactness of a supermassive exotic compact object down to the Planck scale. Our analysis suggests that highly spinning, supermassive binaries at 1-20 Gpc provide unparalleled tests of quantum-gravity effects at the horizon scale.

Disordered quivers and cold horizons

DOE PAGES

Anninos, Dionysios; Anous, Tarek; Denef, Frederik

2016-12-15

We analyze the low temperature structure of a supersymmetric quiver quantum mechanics with randomized superpotential coefficients, treating them as quenched disorder. These theories describe features of the low energy dynamics of wrapped branes, which in large number backreact into extremal black holes. We show that the low temperature theory, in the limit of a large number of bifundamentals, exhibits a time reparametrization symmetry as well as a specific heat linear in the temperature. Both these features resemble the behavior of black hole horizons in the zero temperature limit. We demonstrate similarities between the low temperature physics of the random quivermore » model and a theory of large N free fermions with random masses.« less

Integrability of geodesics in near-horizon extremal geometries: Case of Myers-Perry black holes in arbitrary dimensions

NASA Astrophysics Data System (ADS)

Demirchian, Hovhannes; Nersessian, Armen; Sadeghian, Saeedeh; Sheikh-Jabbari, M. M.

2018-05-01

We investigate dynamics of probe particles moving in the near-horizon limit of extremal Myers-Perry black holes in arbitrary dimensions. Employing ellipsoidal coordinates we show that this problem is integrable and separable, extending the results of the odd dimensional case discussed by Hakobyan et al. [Phys. Lett. B 772, 586 (2017)., 10.1016/j.physletb.2017.07.028]. We find the general solution of the Hamilton-Jacobi equations for these systems and present explicit expressions for the Liouville integrals and discuss Killing tensors and the associated constants of motion. We analyze special cases of the background near-horizon geometry were the system possesses more constants of motion and is hence superintegrable. Finally, we consider a near-horizon extremal vanishing horizon case which happens for Myers-Perry black holes in odd dimensions and show that geodesic equations on this geometry are also separable and work out its integrals of motion.

Acidity in organic horizons of arctic soils on the Barents Sea coast

NASA Astrophysics Data System (ADS)

Shamrikova, E. V.; Deneva, S. V.; Kubik, O. S.; Punegov, V. V.; Kyz”yurova, E. V.; Bobrova, Yu. I.; Zueva, O. M.

2017-11-01

Parameters of water and KCl extracts from organic horizons of arctic soils on the coast of Khaipudyr Bay of the Barents Sea, in which the values of pH are 3.8-4.3 and 2.7-3.5, respectively, have been compared. It has been found that the content of water-extractable organic carbon is 0.2-0.5 g/dm3; the contents of low-molecular-weight carbohydrates and acids are 1-24 and 6 mg/dm3, respectively, and the content of Fe3+ ions is 1-4 mmol/dm3. The increase in the ionic strength of solution reduces the extraction efficiency of total organic carbon in 1.2 times and that of acids and carbohydrates in 3 times on the average at the simultaneous increase in the content of iron ions in the liquid phase in 7-15 times. It has been shown that organic acids and iron compounds are the main sources of acidity in salt extracts from organic soil horizons. The low contents of Ca2+ and Mg2+, which participate in the neutralization of acids, favor the high acidity of the studied horizons.

Hawking radiation and the boomerang behavior of massive modes near a horizon

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jannes, G.; Low Temperature Laboratory, Aalto University School of Science, PO Box 15100, 00076 Aalto; Maiessa, P.

2011-05-15

We discuss the behavior of massive modes near a horizon based on a study of the dispersion relation and wave packet simulations of the Klein-Gordon equation. We point out an apparent paradox between two (in principle equivalent) pictures of black-hole evaporation through Hawking radiation. In the picture in which the evaporation is due to the emission of positive-energy modes, one immediately obtains a threshold for the emission of massive particles. In the picture in which the evaporation is due to the absorption of negative-energy modes, such a threshold apparently does not exist. We resolve this paradox by tracing the evolutionmore » of the positive-energy massive modes with an energy below the threshold. These are seen to be emitted and move away from the black-hole horizon, but they bounce back at a 'red horizon' and are reabsorbed by the black hole, thus compensating exactly for the difference between the two pictures. For astrophysical black holes, the consequences are curious but do not affect the terrestrial constraints on observing Hawking radiation. For analogue-gravity systems with massive modes, however, the consequences are crucial and rather surprising.« less

The effect of moisture content on the thermal conductivity of moss and organic soil horizons from black spruce ecosystems in interior alaska

USGS Publications Warehouse

O'Donnell, J. A.; Romanovsky, V.E.; Harden, J.W.; McGuire, A.D.

2009-01-01

Organic soil horizons function as important controls on the thermal state of near-surface soil and permafrost in high-latitude ecosystems. The thermal conductivity of organic horizons is typically lower than mineral soils and is closely linked to moisture content, bulk density, and water phase. In this study, we examined the relationship between thermal conductivity and soil moisture for different moss and organic horizon types in black spruce ecosystems of interior Alaska. We sampled organic horizons from feather moss-dominated and Sphagnum-dominated stands and divided horizons into live moss and fibrous and amorphous organic matter. Thermal conductivity measurements were made across a range of moisture contents using the transient line heat source method. Our findings indicate a strong positive and linear relationship between thawed thermal conductivity (Kt) and volumetric water content. We observed similar regression parameters (?? or slope) across moss types and organic horizons types and small differences in ??0 (y intercept) across organic horizon types. Live Sphagnum spp. had a higher range of Kt than did live feather moss because of the field capacity (laboratory based) of live Sphagnum spp. In northern regions, the thermal properties of organic soil horizons play a critical role in mediating the effects of climate warming on permafrost conditions. Findings from this study could improve model parameterization of thermal properties in organic horizons and enhance our understanding of future permafrost and ecosystem dynamics. ?? 2009 by Lippincott Williams & Wilkins, Inc.

HORIZON RUN 3: TOPOLOGY AS A STANDARD RULER

DOE Office of Scientific and Technical Information (OSTI.GOV)

Speare, Robert; Gott, J. Richard; Kim, Juhan

2015-02-01

We study the physically self-bound cold dark matter halo distribution, which we associate with the massive galaxies within Horizon Run 3, to estimate the accuracy of the determination of the cosmological distance scale measured by the topology analysis. We apply the routine '''Contour 3D''' to the 108 Mock Survey of π steradians out to redshift z = 0.6, which effectively corresponds to the SDSS-III Baryon Oscillation Spectroscopic Survey (BOSS) survey, and compare the topology with that of a Gaussian random phase field. We find that given three separate smoothing lengths λ = 15, 21, and 34 h {sup –1} Mpc,more » the least χ{sup 2} fit genus per unit volume (g) yields a 1.7% fractional uncertainty in smoothing length and angular diameter distance to z = 0.6. This is an improvement on former calibrations and presents an error estimate competitive with baryon acoustic oscillation scale techniques. We also present three-dimensional graphics of the Horizon Run 3 spherical mock survey to show a wealth of large-scale structures of the universe that are expected for surveys like BOSS.« less

Autonomous navigation accuracy using simulated horizon sensor and sun sensor observations

NASA Technical Reports Server (NTRS)

Pease, G. E.; Hendrickson, H. T.

1980-01-01

A relatively simple autonomous system which would use horizon crossing indicators, a sun sensor, a quartz oscillator, and a microprogrammed computer is discussed. The sensor combination is required only to effectively measure the angle between the centers of the Earth and the Sun. Simulations for a particular orbit indicate that 2 km r.m.s. orbit determination uncertainties may be expected from a system with 0.06 deg measurement uncertainty. A key finding is that knowledge of the satellite orbit plane orientation can be maintained to this level because of the annual motion of the Sun and the predictable effects of Earth oblateness. The basic system described can be updated periodically by transits of the Moon through the IR horizon crossing indicator fields of view.

Modelling health and output at business cycle horizons for the USA.

PubMed

Narayan, Paresh Kumar

2010-07-01

In this paper we employ a theoretical framework - a simple macro model augmented with health - that draws guidance from the Keynesian view of business cycles to examine the relative importance of permanent and transitory shocks in explaining variations in health expenditure and output at business cycle horizons for the USA. The variance decomposition analysis of shocks reveals that at business cycle horizons permanent shocks explain the bulk of the variations in output, while transitory shocks explain the bulk of the variations in health expenditures. We undertake a shock decomposition analysis for private health expenditures versus public health expenditures and interestingly find that while transitory shocks are more important for private sector expenditures, permanent shocks dominate public health expenditures. Copyright (c) 2009 John Wiley & Sons, Ltd.

Through the looking glass: why the `cosmic horizon' is not a horizon

NASA Astrophysics Data System (ADS)

van Oirschot, Pim; Kwan, Juliana; Lewis, Geraint F.

2010-06-01

The present standard model of cosmology, Λ cold dark matter (ΛCDM), contains some intriguing coincidences. Not only are the dominant contributions to the energy density approximately of the same order at the present epoch, but we also note that contrary to the emergence of cosmic acceleration as a recent phenomenon, the time-averaged value of the deceleration parameter over the age of the Universe is nearly zero. Curious features like these in ΛCDM give rise to a number of alternate cosmologies being proposed to remove them, including models with an equation of state w = -1/3. In this paper, we examine the validity of some of these alternate models and we also address some persistent misconceptions about the Hubble sphere and the event horizon that lead to erroneous conclusions about cosmology. Research undertaken as part of the Commonwealth Cosmology Initiative (CCI: http://www.thecci.org), an international collaboration supported by the Australian Research Council. E-mail: pimvanoirschot@gmail.com

Advanced expander test bed program

NASA Technical Reports Server (NTRS)

Masters, A. I.; Mitchell, J. C.

1991-01-01

The Advanced Expander Test Bed (AETB) is a key element in NASA's Chemical Transfer Propulsion Program for development and demonstration of expander cycle oxygen/hydrogen engine technology component technology for the next space engine. The AETB will be used to validate the high-pressure expander cycle concept, investigate system interactions, and conduct investigations of advanced missions focused components and new health monitoring techniques. The split-expander cycle AETB will operate at combustion chamber pressures up to 1200 psia with propellant flow rates equivalent to 20,000 lbf vacuum thrust.

New Horizons: An Empowerment Program for Egyptian Adolescent Girls.

ERIC Educational Resources Information Center

Swanson, Julie Hanson

New Horizons is a nonschool program that demystifies and communicates essential information on basic life skills and reproductive health to Egyptian girls and young women aged 9-20. The program consists of 100 hour-long sessions, each including an introduction to a specific topic, review of group knowledge level, discussion around key points…

The terminal Permian in European Russia: Vyaznikovian Horizon, Nedubrovo Member, and Permian-Triassic boundary

NASA Astrophysics Data System (ADS)

Lozovsky, V. R.; Balabanov, Yu. P.; Karasev, E. V.; Novikov, I. V.; Ponomarenko, A. G.; Yaroshenko, O. P.

2016-07-01

The comprehensive analysis of the data obtained on terrestrial vertebrata, ostracods, entomologic fauna, megaflora, and microflora in deposits of the Vyaznikovian Horizon and Nedubrovo Member, as well as the paleomagnetic data measured in enclosing rocks, confirms heterogeneity of these deposits. Accordingly, it is necessary to distinguish these two stratons in the terminal Permian of the East European Platform. The combined sequence of Triassic-Permian boundary deposits in the Moscow Syneclise, which is considered to be the most complete sequence in the East European Platform, is as follows (from bottom upward): Vyatkian deposits; Vyaznikovian Horizon, including Sokovka and Zhukovo members; Nedubrovo Member (Upper Permian); Astashikha and Ryabi members of the Vokhmian Horizon (Lower Triassic). None of the sequences of Permian-Triassic boundary deposits known in the area of study characterizes this sequence in full volume. In the north, the Triassic deposits are underlain by the Nedubrovo Member; in the south (the Klyazma River basin), the sections are underlain by the Vyaznikovian Horizon. The Permian-Triassic boundary adopted in the General Stratigraphic Scale of Russia for continental deposits of the East European platform (the lower boundary of the Astashikha Member) is more ancient than the one adopted in the International Stratigraphic Chart. The same geological situation is observed in the German Basin and other localities where Triassic continental deposits are developed. The ways of solving this problem are discussed in this article.

Birth of plant proteomics in India: a new horizon.

PubMed

Narula, Kanika; Pandey, Aarti; Gayali, Saurabh; Chakraborty, Niranjan; Chakraborty, Subhra

2015-09-08

In the post-genomic era, proteomics is acknowledged as the next frontier for biological research. Although India has a long and distinguished tradition in protein research, the initiation of proteomics studies was a new horizon. Protein research witnessed enormous progress in protein separation, high-resolution refinements, biochemical identification of the proteins, protein-protein interaction, and structure-function analysis. Plant proteomics research, in India, began its journey on investigation of the proteome profiling, complexity analysis, protein trafficking, and biochemical modeling. The research article by Bhushan et al. in 2006 marked the birth of the plant proteomics research in India. Since then plant proteomics studies expanded progressively and are now being carried out in various institutions spread across the country. The compilation presented here seeks to trace the history of development in the area during the past decade based on publications till date. In this review, we emphasize on outcomes of the field providing prospects on proteomic pathway analyses. Finally, we discuss the connotation of strategies and the potential that would provide the framework of plant proteome research. The past decades have seen rapidly growing number of sequenced plant genomes and associated genomic resources. To keep pace with this increasing body of data, India is in the provisional phase of proteomics research to develop a comparative hub for plant proteomes and protein families, but it requires a strong impetus from intellectuals, entrepreneurs, and government agencies. Here, we aim to provide an overview of past, present and future of Indian plant proteomics, which would serve as an evaluation platform for those seeking to incorporate proteomics into their research programs. This article is part of a Special Issue entitled: Proteomics in India. Copyright © 2015 Elsevier B.V. All rights reserved.

Ectomycorrhizal-dominated boreal and tropical forests have distinct fungal communities, but analogous spatial patterns across soil horizons.

PubMed

McGuire, Krista L; Allison, Steven D; Fierer, Noah; Treseder, Kathleen K

2013-01-01

Fungi regulate key nutrient cycling processes in many forest ecosystems, but their diversity and distribution within and across ecosystems are poorly understood. Here, we examine the spatial distribution of fungi across a boreal and tropical ecosystem, focusing on ectomycorrhizal fungi. We analyzed fungal community composition across litter (organic horizons) and underlying soil horizons (0-20 cm) using 454 pyrosequencing and clone library sequencing. In both forests, we found significant clustering of fungal communities by site and soil horizons with analogous patterns detected by both sequencing technologies. Free-living saprotrophic fungi dominated the recently-shed leaf litter and ectomycorrhizal fungi dominated the underlying soil horizons. This vertical pattern of fungal segregation has also been found in temperate and European boreal forests, suggesting that these results apply broadly to ectomycorrhizal-dominated systems, including tropical rain forests. Since ectomycorrhizal and free-living saprotrophic fungi have different influences on soil carbon and nitrogen dynamics, information on the spatial distribution of these functional groups will improve our understanding of forest nutrient cycling.

Can test fields destroy the event horizon in the Kerr–Taub–NUT spacetime?

NASA Astrophysics Data System (ADS)

Düztaş, Koray

2018-02-01

In this work we investigate if the interaction of the Kerr–Taub–NUT spacetime with test scalar and neutrino fields can lead to the destruction of the event horizon. It turns out that both extremal and nearly extremal black holes can be destroyed by scalar and neutrino fields if the initial angular momentum of the spacetime is sufficiently large relative to its mass and NUT charge. This is the first example in which a classical field satisfying the null energy condition can actually destroy an extremal black hole. For scalar fields, the modes that can lead to the destruction of the horizon are restricted to a narrow range due to superradiance. Since superradiance does not occur for neutrino fields, the destruction of the horizon by neutrino fields is generic, and it cannot be fixed by backreaction effects. We also show that the extremal black holes that can be destroyed by scalar fields correspond to naked singularities in the Kerr limit, in accord with the previous results which imply that extremal Kerr black holes cannot be destroyed by scalar test fields.

Optimization-Based Sensor Fusion of GNSS and IMU Using a Moving Horizon Approach

PubMed Central

Girrbach, Fabian; Hol, Jeroen D.; Bellusci, Giovanni; Diehl, Moritz

2017-01-01

The rise of autonomous systems operating close to humans imposes new challenges in terms of robustness and precision on the estimation and control algorithms. Approaches based on nonlinear optimization, such as moving horizon estimation, have been shown to improve the accuracy of the estimated solution compared to traditional filter techniques. This paper introduces an optimization-based framework for multi-sensor fusion following a moving horizon scheme. The framework is applied to the often occurring estimation problem of motion tracking by fusing measurements of a global navigation satellite system receiver and an inertial measurement unit. The resulting algorithm is used to estimate position, velocity, and orientation of a maneuvering airplane and is evaluated against an accurate reference trajectory. A detailed study of the influence of the horizon length on the quality of the solution is presented and evaluated against filter-like and batch solutions of the problem. The versatile configuration possibilities of the framework are finally used to analyze the estimated solutions at different evaluation times exposing a nearly linear behavior of the sensor fusion problem. PMID:28534857

Importance of a midterm time horizon for addressing ethical issues integral to nanobiotechnology.

PubMed

Khushf, George

2007-01-01

There is a consensus emerging on the importance of upstream ethical engagement in nanobiotechnology. Such a preventive ethic would anticipate downstream concerns that might arise and mitigate them as part of the research and development process. However, there is an unappreciated tension between the time horizon of upstream ethics and that assumed by most bioethical research. Current standards of high-quality research on ethical issues biases the research in favor of near-term, science-based, results-oriented work. A near-term focus would miss many of the important ethical issues integral to nanobiotechnology and undermine the goals integral to upstream ethical engagement. However, if we move to a far-term time horizon, the ethical debates tend to get too speculative and are no longer disciplined by existing research trajectories. This paper addresses the link between the midterm time horizon necessary for upstream ethics and the form, content, and style of ethical reflection. New paradigm cases, standards, and criteria will be needed for high-quality upstream ethics work in the area of nanobiotechnology.

Optimization-Based Sensor Fusion of GNSS and IMU Using a Moving Horizon Approach.

PubMed

Girrbach, Fabian; Hol, Jeroen D; Bellusci, Giovanni; Diehl, Moritz

2017-05-19

The rise of autonomous systems operating close to humans imposes new challenges in terms of robustness and precision on the estimation and control algorithms. Approaches based on nonlinear optimization, such as moving horizon estimation, have been shown to improve the accuracy of the estimated solution compared to traditional filter techniques. This paper introduces an optimization-based framework for multi-sensor fusion following a moving horizon scheme. The framework is applied to the often occurring estimation problem of motion tracking by fusing measurements of a global navigation satellite system receiver and an inertial measurement unit. The resulting algorithm is used to estimate position, velocity, and orientation of a maneuvering airplane and is evaluated against an accurate reference trajectory. A detailed study of the influence of the horizon length on the quality of the solution is presented and evaluated against filter-like and batch solutions of the problem. The versatile configuration possibilities of the framework are finally used to analyze the estimated solutions at different evaluation times exposing a nearly linear behavior of the sensor fusion problem.

Horizon-Specific Bacterial Community Composition of German Grassland Soils, as Revealed by Pyrosequencing-Based Analysis of 16S rRNA Genes ▿ †

PubMed Central

Will, Christiane; Thürmer, Andrea; Wollherr, Antje; Nacke, Heiko; Herold, Nadine; Schrumpf, Marion; Gutknecht, Jessica; Wubet, Tesfaye; Buscot, François; Daniel, Rolf

2010-01-01

The diversity of bacteria in soil is enormous, and soil bacterial communities can vary greatly in structure. Here, we employed a pyrosequencing-based analysis of the V2-V3 16S rRNA gene region to characterize the overall and horizon-specific (A and B horizons) bacterial community compositions in nine grassland soils, which covered three different land use types. The entire data set comprised 752,838 sequences, 600,544 of which could be classified below the domain level. The average number of sequences per horizon was 41,824. The dominant taxonomic groups present in all samples and horizons were the Acidobacteria, Betaproteobacteria, Actinobacteria, Gammaproteobacteria, Alphaproteobacteria, Deltaproteobacteria, Chloroflexi, Firmicutes, and Bacteroidetes. Despite these overarching dominant taxa, the abundance, diversity, and composition of bacterial communities were horizon specific. In almost all cases, the estimated bacterial diversity (H′) was higher in the A horizons than in the corresponding B horizons. In addition, the H′ was positively correlated with the organic carbon content, the total nitrogen content, and the C-to-N ratio, which decreased with soil depth. It appeared that lower land use intensity results in higher bacterial diversity. The majority of sequences affiliated with the Actinobacteria, Bacteroidetes, Cyanobacteria, Fibrobacteres, Firmicutes, Spirochaetes, Verrucomicrobia, Alphaproteobacteria, Betaproteobacteria, and Gammaproteobacteria were derived from A horizons, whereas the majority of the sequences related to Acidobacteria, Chloroflexi, Gemmatimonadetes, Nitrospira, TM7, and WS3 originated from B horizons. The distribution of some bacterial phylogenetic groups and subgroups in the different horizons correlated with soil properties such as organic carbon content, total nitrogen content, or microbial biomass. PMID:20729324

Inflight Radiometric Calibration of New Horizons' Multispectral Visible Imaging Camera (MVIC)

NASA Technical Reports Server (NTRS)

Howett, C. J. A.; Parker, A. H.; Olkin, C. B.; Reuter, D. C.; Ennico, K.; Grundy, W. M.; Graps, A. L.; Harrison, K. P.; Throop, H. B.; Buie, M. W.;

Horizon fluffs: In the context of generalized minimal massive gravity

NASA Astrophysics Data System (ADS)

Setare, Mohammad Reza; Adami, Hamed

2018-02-01

We consider a metric which describes Bañados geometries and show that the considered metric is a solution of the generalized minimal massive gravity (GMMG) model. We consider the Killing vector field which preserves the form of the considered metric. Using the off-shell quasi-local approach we obtain the asymptotic conserved charges of the given solution. Similar to the Einstein gravity in the presence of negative cosmological constant, for the GMMG model, we also show that the algebra among the asymptotic conserved charges is isomorphic to two copies of the Virasoro algebra. Eventually, we find a relation between the algebra of the near-horizon and the asymptotic conserved charges. This relation shows that the main part of the horizon fluffs proposed by Afshar et al., Sheikh-Jabbari and Yavartanoo appear for generic black holes in the class of Bañados geometries in the context of the GMMG model.

Chandra Uncovers New Evidence For Event Horizons Surrounding Black Holes

NASA Astrophysics Data System (ADS)

2001-01-01

SAN DIEGO -- Astronomers have used NASA's Chandra X-ray Observatory to study some of the darkest black holes yet observed. Their work strongly confirms the reality of the "event horizon," the one-way membrane around black holes predicted by Einstein's theory of relativity. The findings were presented today at the American Astronomical Society meeting by Drs. Michael Garcia, Jeffrey McClintock, Ramesh Narayan, and Stephen Murray of the Harvard-Smithsonian Center for Astrophysics and Dr. Paul Callanan of University College, Cork, Ireland. With results that fundamentally differ from earlier black hole studies, Garcia and his colleagues have shown that some recently discovered black holes are not only ultra-dense, but actually possess event horizons that "vacuum up" energy from their surroundings. "It is a bit odd to say we've discovered something by seeing almost nothing at all -- less than the smile of the Cheshire cat, so to speak," said Garcia, lead author on a paper submitted to the Astrophysical Journal, "but, in essence, this is what we have done." Using data from Chandra and previous X-ray satellites like ROSAT, the Chandra team studied a dozen "X-ray novas," so named because they occasionally erupt as brilliant X-ray sources then settle into decades of dormancy. The great outpouring of X rays is due to a stream of gas that is pulled from the surface of a Sun-like companion star onto a compact object, either a black hole or a neutron star. By comparing the energy output from the dormant X-ray novas, the team discovered that the sources with black holes emitted only one percent as much energy while dormant as did the X-ray novae with neutron stars. "The most straightforward explanation of these observations is that the black hole candidates we have studied have event horizons that swallow just about all of the energy that surrounds them," said Murray. "Indeed, one could even say that this work shows why black holes deserve to be called ‘black.’" "The event

Tissue Expander versus Tissue Expander and Latissimus Flap in Morbidly Obese Breast Reconstruction Patients

PubMed Central

Adams, Robert L.; Chandler, Robert G.; Parks, Joseph

2015-01-01

Background: Immediate postmastectomy breast reconstruction in morbidly obese patients represents a challenge because neither prosthetic nor abdominal-based options may be suitable. Methods: This study compared a previously published cohort of immediate prosthetic reconstruction of 346 patients (511 breasts) of whom 49 patients (67 breasts) were morbidly obese (defined as a body mass index > 35) with a morbidly obese patient population whose breasts were reconstructed immediately following postmastectomy with latissimus flap and tissue expander (21 patients and 22 breasts) in the same time period. The preoperative risk factors of mastectomy such as tobacco use, diabetes, and prior radiation and the postoperative complications of mastectomy such as skin necrosis, seroma, and prosthesis loss were examined. The explantation of the tissue expander provided a defined endpoint of reconstruction failure. Results: The average body mass index in the tissue expander/implant group and in the latissimus flap plus tissue expander/implant group was 40.9 and 40.1, respectively. The risk profile of diabetes and tobacco use was similar in both groups. Fifteen of the 67 breasts (22.3%) of the tissue expander/implant group and 15 of the 23 breasts (65.2%) of the latissimus flap group had received prior radiation. The prosthesis loss was 13 of 67 breasts (19.4%) that had tissue-expander–alone reconstruction and 1 of 22 (4.8%) in the latissimus group that had tissue expander reconstruction. Modification of donor-site incision and skin-island location in the latissimus group of patients can minimize scar deformity. Conclusion: The loss rate in immediate postmastectomy reconstruction in morbidly obese patients with latissimus flap plus tissue expander was substantially lower than the loss rate in those with breast reconstructed with tissue expander alone. PMID:25878934

Destination pluto: New horizons performance during the approach phase

NASA Astrophysics Data System (ADS)

Flanigan, Sarah H.; Rogers, Gabe D.; Guo, Yanping; Kirk, Madeline N.; Weaver, Harold A.; Owen, William M.; Jackman, Coralie D.; Bauman, Jeremy; Pelletier, Frederic; Nelson, Derek; Stanbridge, Dale; Dumont, Phillip J.; Williams, Bobby; Stern, S. Alan; Olkin, Cathy B.; Young, Leslie A.; Ennico, Kimberly

2016-11-01

The New Horizons spacecraft began its journey to the Pluto-Charon system on January 19, 2006 on-board an Atlas V rocket from Cape Canaveral, Florida. As the first mission in NASA's New Frontiers program, the objective of the New Horizons mission is to perform the first exploration of ice dwarfs in the Kuiper Belt, extending knowledge of the solar system to include the icy "third zone" for the first time. Arriving at the correct time and correct position relative to Pluto on July 14, 2015 depended on the successful execution of a carefully choreographed sequence of events. The Core command sequence, which was developed and optimized over multiple years and included the highest-priority science observations during the closest approach period, was contingent on precise navigation to the Pluto-Charon system and nominal performance of the guidance and control (G&C) subsystem. The flyby and gravity assist of Jupiter on February 28, 2007 was critical in placing New Horizons on the path to Pluto. Once past Jupiter, trajectory correction maneuvers (TCMs) became the sole source of trajectory control since the spacecraft did not encounter any other planetary bodies along its flight path prior to Pluto. During the Pluto approach phase, which formally began on January 15, 2015, optical navigation images were captured primarily with the Long Range Reconnaissance Imager to refine spacecraft and Pluto-Charon system trajectory knowledge, which in turn was used to design TCMs. Orbit determination solutions were also used to update the spacecraft's on-board trajectory knowledge throughout the approach phase. Nominal performance of the G&C subsystem, accurate TCM designs, and high-quality orbit determination solutions resulted in final Pluto-relative B-plane arrival conditions that facilitated a successful first reconnaissance of the Pluto-Charon system.

Expandable Lunar Habitat (X-Hab)

NASA Image and Video Library

2010-09-23

Expandable Lunar Habitat (X-Hab).ILC Dover, under contract by NASA Langley Research Center, and in cooperation with NASA Johnson Space Center has designed and manufactured an expandable lunar habitat. This cylindrical habitat, or Expandable Lunar Habitat (X-Hab) is a hybrid system with two hard end caps and a deployable softgoods section in the center.

Short paths in expander graphs

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kleinberg, J.; Rubinfeld, R.

Graph expansion has proved to be a powerful general tool for analyzing the behavior of routing algorithms and the interconnection networks on which they run. We develop new routing algorithms and structural results for bounded-degree expander graphs. Our results are unified by the fact that they are all based upon, and extend, a body of work asserting that expanders are rich in short, disjoint paths. In particular, our work has consequences for the disjoint paths problem, multicommodify flow, and graph minor containment. We show: (i) A greedy algorithm for approximating the maximum disjoint paths problem achieves a polylogarithmic approximation ratiomore » in bounded-degree expanders. Although our algorithm is both deterministic and on-line, its performance guarantee is an improvement over previous bounds in expanders. (ii) For a multicommodily flow problem with arbitrary demands on a bounded-degree expander, there is a (1 + {epsilon})-optimal solution using only flow paths of polylogarithmic length. It follows that the multicommodity flow algorithm of Awerbuch and Leighton runs in nearly linear time per commodity in expanders. Our analysis is based on establishing the following: given edge weights on an expander G, one can increase some of the weights very slightly so the resulting shortest-path metric is smooth - the min-weight path between any pair of nodes uses a polylogarithmic number of edges. (iii) Every bounded-degree expander on n nodes contains every graph with O(n/log{sup O(1)} n) nodes and edges as a minor.« less

Peering beyond the horizon with standard sirens and redshift drift

NASA Astrophysics Data System (ADS)

Jimenez, Raul; Raccanelli, Alvise; Verde, Licia; Matarrese, Sabino

2018-04-01

An interesting test on the nature of the Universe is to measure the global spatial curvature of the metric in a model independent way, at a level of |Ωk|<10‑4, or, if possible, at the cosmic variance level of the amplitude of the CMB fluctuations |Ωk|≈10‑5. A limit of |Ωk|<10‑4 would yield stringent tests on several models of inflation. Further, improving the constraint by an order of magnitude would help in reducing "model confusion" in standard parameter estimation. Moreover, if the curvature is measured to be at the value of the amplitude of the CMB fluctuations, it would offer a powerful test on the inflationary paradigm and would indicate that our Universe must be significantly larger than the current horizon. On the contrary, in the context of standard inflation, measuring a value above CMB fluctuations will lead us to conclude that the Universe is not much larger than the current observed horizon; this can also be interpreted as the presence of large fluctuations outside the horizon. However, it has proven difficult, so far, to find observables that can achieve such level of accuracy, and, most of all, be model-independent. Here we propose a method that can in principle achieve that; this is done by making minimal assumptions and using distance probes that are cosmology-independent: gravitational waves, redshift drift and cosmic chronometers. We discuss what kind of observations are needed in principle to achieve the desired accuracy.

Advanced expander test bed engine

NASA Technical Reports Server (NTRS)

Mitchell, J. P.

1992-01-01

The Advanced Expander Test Bed (AETB) is a key element in NASA's Space Chemical Engine Technology Program for development and demonstration of expander cycle oxygen/hydrogen engine and advanced component technologies applicable to space engines as well as launch vehicle upper stage engines. The AETB will be used to validate the high pressure expander cycle concept, study system interactions, and conduct studies of advanced mission focused components and new health monitoring techniques in an engine system environment. The split expander cycle AETB will operate at combustion chamber pressures up to 1200 psia with propellant flow rates equivalent to 20,000 lbf vacuum thrust.

Observational Limits for Rings and Debris at Pluto from New Horizons

NASA Astrophysics Data System (ADS)

Throop, Henry B.; Lauer, Tod R.; Showalter, Mark R.; Weaver, Harold A.; Stern, S. Alan; Spencer, John R.; Buie, Marc W.; Hamilton, Douglas P.; Porter, Simon Bernard; Verbiscer, Anne J.; Young, Leslie; Olkin, Catherine; Ennico, Kimberly; New Horizons Science Team

2017-10-01

NASA's New Horizons missions flew past Pluto on July 14, 2015. New Horizons conducted an extensive search for orbital material at Pluto, using deep imaging at backscatter and forward-scatter, direct in situ dust detector measurements, and stellar occultations. We searched the entire region from the surface of Pluto outward to the Pluto-Charon Hill radius (6.4 x 106 km = 100 times Hydra's orbital radius), using the spacecraft's LORRI and MVIC cameras.No material was found to a normal I/F limit of 2 x 10-8 for 1500 km-wide rings, and 7 x 10-9 for 12,000 km-wide rings. Our results are consistent with dynamical studies that show the lifetime of dust in the Pluto system is short, with the loss dominated by solar radiation pressure and gravitational perturbations.

Ecological Impacts of the Deepwater Horizon Oil Spill (Bogota, Columbia)

EPA Science Inventory

The Deepwater Horizon oil spill (DWH) was the largest environmental disaster and response effort in US History, with nearly 800 million liters spilled. Vast areas of the Gulf of Mexico were contaminated with oil, including deep ocean communities, protected species, over 1600 km o...

Functional Assays and Metagenomic Analyses Reveals Differences between the Microbial Communities Inhabiting the Soil Horizons of a Norway Spruce Plantation

PubMed Central

Uroz, Stéphane; Ioannidis, Panos; Lengelle, Juliette; Cébron, Aurélie; Morin, Emmanuelle; Buée, Marc; Martin, Francis

2013-01-01

In temperate ecosystems, acidic forest soils are among the most nutrient-poor terrestrial environments. In this context, the long-term differentiation of the forest soils into horizons may impact the assembly and the functions of the soil microbial communities. To gain a more comprehensive understanding of the ecology and functional potentials of these microbial communities, a suite of analyses including comparative metagenomics was applied on independent soil samples from a spruce plantation (Breuil-Chenue, France). The objectives were to assess whether the decreasing nutrient bioavailability and pH variations that naturally occurs between the organic and mineral horizons affects the soil microbial functional biodiversity. The 14 Gbp of pyrosequencing and Illumina sequences generated in this study revealed complex microbial communities dominated by bacteria. Detailed analyses showed that the organic soil horizon was significantly enriched in sequences related to Bacteria, Chordata, Arthropoda and Ascomycota. On the contrary the mineral horizon was significantly enriched in sequences related to Archaea. Our analyses also highlighted that the microbial communities inhabiting the two soil horizons differed significantly in their functional potentials according to functional assays and MG-RAST analyses, suggesting a functional specialisation of these microbial communities. Consistent with this specialisation, our shotgun metagenomic approach revealed a significant increase in the relative abundance of sequences related glycoside hydrolases in the organic horizon compared to the mineral horizon that was significantly enriched in glycoside transferases. This functional stratification according to the soil horizon was also confirmed by a significant correlation between the functional assays performed in this study and the functional metagenomic analyses. Together, our results suggest that the soil stratification and particularly the soil resource availability impact the

Integrating horizon scanning and strategic risk prioritisation using a weight of evidence framework to inform policy decisions.

PubMed

Garnett, K; Lickorish, F A; Rocks, S A; Prpich, G; Rathe, A A; Pollard, S J T

2016-08-01

Poor connection between data on emerging issues and credible policy decisions continues to challenge governments, and is only likely to grow as demands on time and resources increase. Here we summarise recent efforts to integrate horizon scanning and risk prioritisation approaches to better connect emerging issues to the political discourse on environmental and food-related issues. Our categorisation of insights including potential future risks and opportunities to inform policy discussions has emerged from a structured three-year programme of horizon scanning for a UK pan-governmental futures partnership led by the Department for Environment, Food and Rural Affairs (Defra). Our efforts to integrate horizon scanning and risk prioritisation, utilising a qualitative weight of evidence framework, has created a systematic process for identifying all signals of potential future change with significant impact for the strategic mission and underlying values of policy actors. Our approach encourages an exploration of factors out of the control of organisations, recognising that resilience depends on the flexibility of management strategies and the preparedness to deal with a variety of unexpected outcomes. We discuss how this approach addresses key cultural and evaluative challenges that policy actors have had in embedding horizon scanning in evidence-based policy processes, and suggest further developments to build confidence in the use of horizon scanning for strategic planning. Copyright © 2016 Elsevier B.V. All rights reserved.

Rethinking Classroom Management: A New Perspective, a New Horizon

ERIC Educational Resources Information Center

Toprakci, Erdal

2012-01-01

The purpose of this study is to suggest a new perspective and a new horizon by analyzing the concept of classroom management in the literature of traditional classroom management from a scientific and dictionary view. It may be said that there are serious problems regarding the settlement of the meaning of "classroom management" in the educational…

The Precision Expandable Radar Calibration Sphere (PERCS) With Applications for Laser Imaging and Ranging

NASA Astrophysics Data System (ADS)

Bernhardt, P.; Nicholas, A.; Thomas, L.; Davis, M.; Hoberman, C.; Davis, M.

The Naval Research Laboratory will provide an orbiting calibration sphere to be used with ground-based laser imaging telescopes and HF radio systems. The Precision Expandable Radar Calibration Sphere (PERCS) is a practical, reliable, high-performance HF calibration sphere and laser imaging target to orbit at about 600 km altitude. The sphere will be made of a spherical wire frame with aspect independent radar cross section in the 3 to 35 MHz frequency range. The necessary launch vehicle to place the PERCS in orbit will be provided by the Department of Defense Space Test Program. The expandable calibration target has a stowed diameter of 1 meter and a fully deployed diameter of 10.2 meters. A separate deployment mechanism is provided for the sphere. After deployment, the Precision Expandable Radar Calibration Sphere (PERCS) with 180 vertices will be in a high inclination orbit to scatter radio pulses from a number of ground systems, including (1) over-the-horizon (OTH) radars operated by the United States and Australia; (2) high power HF facilities such as HAARP in Alaska, EISCAT in Norway, and Arecibo in Puerto Rico; (3) the chain of high latitude SuperDARN radars used for auroral region mapping; and (4) HF direction finding for Navy ships. With the PERCS satellite, the accuracy of HF radars can be periodically checked for range, elevation, and azimuth errors. In addition, each of the 360 vertices on the PERCS sphere will support an optical retro-reflector for operations with ground laser facilities used to track satellites. The ground laser systems will be used to measure the precise location of the sphere within one cm accuracy and will provide the spatial orientation of the sphere as well as the rotation rate. The Department of Defense facilities that can use the corner-cube reflectors on the PERCS include (1) the Air Force Maui Optical Site (AMOS), (2) the Starfire Optical Range (SOR), and (3) the NRL Optical Test Facility (OTF).

Dust Measurements On-board the New Horizons Mission

NASA Astrophysics Data System (ADS)

Poppe, A.; James, D.; Horanyi, M.

2007-12-01

The Venetia Burney Student Dust Counter (VSDC) on the New Horizons spacecraft was successfully commissioned on March 3, 2006 (DOY 2006/061). VSDC is a dust impact detector designed to map the dust distribution along the trajectory of the New Horizons spacecraft as it traverses our solar system. VSDC is the first student built instrument on a deep space mission and it is currently operated by a small group of undergraduate and graduate students at the Laboratory of Atmospheric and Space Physics (LASP), University of Colorado. By the time of this meeting (12/2007), VSDC will have operated for about 330 days, covering an approximate distance from 1.21 to 10 AU. VSDC is based on permanently polarized thin plastic film sensors that generate an electrical signal when an impacting dust particle penetrates them. The total surface area is about 0.1 square meters, and the detection threshold is about a micron in particle radius. In this talk we will briefly review the VSDC instrument. The in-flight tests and calibrations, as well as our initial science results will be discussed. We will report on the measured spatial and size distribution of interplanetary dust particles before and after the encounter with Jupiter. These measurements will be compared with earlier measurements by Ulysses, Galileo, and Cassini.

New Horizons Observations of the Atmospheres of Pluto and Charon

NASA Astrophysics Data System (ADS)

Gladstone, G. R.; Stern, S. A.; Weaver, H. A.; Young, L. A.; Ennico, K. A.; Olkin, C. B.; Cheng, A. F.; Greathouse, T. K.; Hinson, D. P.; Kammer, J. A.; Linscott, I. R.; Parker, A. H.; Parker, J. Wm.; Retherford, K. D.; Schindhelm, E.; Singer, K. N.; Steffl, A. J.; Strobel, D. F.; Summers, M. E.; Tsang, C. C. C.; Tyler, G. L.; Versteeg, M. H.; Woods, W. W.; Cunningham, N.; Curdt, W.

2015-11-01

Major goals of the New Horizons (NH) mission are to explore and characterize the structure and composition of Pluto’s atmosphere, and to establish whether Charon has a measurable atmosphere of its own. The primary instruments onboard NH which contribute to these goals are the REX instrument, through uplink X-band radio occultations, the Alice instrument, through extreme- and far-ultraviolet solar occultations, and the LORRI panchromatic imager, through high-phase-angle imaging. The associated datasets were obtained following closest approach of NH to Pluto. Pressure and temperature profiles of the lower atmosphere are derived from the REX data, the composition and structure of the extended atmosphere are derived from the Alice data (supported by approach observations of reflected ultraviolet sunlight), and the distribution and properties of Pluto’s hazes are derived from the LORRI data. In this talk an overview of the early atmosphere science results will be presented.This work was supported by NASA's New Horizons project.

New Horizons High-Phase Observations of Distant Kuiper Belt Objects

NASA Astrophysics Data System (ADS)

Verbiscer, A.; Porter, S.; Spencer, J. R.; Buie, M. W.; Benecchi, S.; Weaver, H. A., Jr.; Buratti, B. J.; Ennico Smith, K.; Olkin, C.; Stern, S. A.; Young, L. A.; Cheng, A. F.

2017-12-01

From its unique vantage point far from the Sun, NASA's New Horizons spacecraft has observed Kuiper Belt Objects at separations ranging from 0.1 to 70 AU, and at solar phase angles far larger than those attainable from Earth. We have constructed the first KBO solar phase curves with substantial phase angle coverage for targets including Haumea, Makemake, Quaoar, Arawn (Porter et al. 2016, Astrophys. J. Lett. 828, L15), and 2002 MS4. We compare the phase functions of these KBOs with those of objects in the Pluto system and other Solar System bodies such as comets, asteroids, and icy satellites. For KBOs with known geometric albedos, these measurements enable calculation of the phase integral, an important photometric property that characterizes the energy balance on a distant KBO surface. During its approach to 2014 MU69, and following its close encounter on 1 January 2019, New Horizons will continue to exploit its capabilities as NASA's only observatory within the Kuiper Belt itself.

Real-time moving horizon estimation for a vibrating active cantilever

NASA Astrophysics Data System (ADS)

Abdollahpouri, Mohammad; Takács, Gergely; Rohaľ-Ilkiv, Boris

2017-03-01

Vibrating structures may be subject to changes throughout their operating lifetime due to a range of environmental and technical factors. These variations can be considered as parameter changes in the dynamic model of the structure, while their online estimates can be utilized in adaptive control strategies, or in structural health monitoring. This paper implements the moving horizon estimation (MHE) algorithm on a low-cost embedded computing device that is jointly observing the dynamic states and parameter variations of an active cantilever beam in real time. The practical behavior of this algorithm has been investigated in various experimental scenarios. It has been found, that for the given field of application, moving horizon estimation converges faster than the extended Kalman filter; moreover, it handles atypical measurement noise, sensor errors or other extreme changes, reliably. Despite its improved performance, the experiments demonstrate that the disadvantage of solving the nonlinear optimization problem in MHE is that it naturally leads to an increase in computational effort.

A horizon scan for species conservation by zoos and aquariums.

PubMed

Gusset, Markus; Fa, John E; Sutherland, William J

2014-01-01

We conducted the first horizon scan for zoos and aquariums to identify the 10 most important emerging issues for species conservation. This involved input from more than 100 experts from both the wider conservation community and the world zoo and aquarium community. Some of the issues are globally important: diseases, zoonoses, and biosecurity issues; new (communication) technologies; global water shortage and food insecurity; developing economies and markets for wildlife consumption; changes in wildlife population dynamics; and political instability and conflicts. Other issues are more specific to zoos and aquariums: need for extractive reserves; space shortage in zoos and aquariums; need for metapopulation management; and demand for caring of more species in zoos and aquariums. We also identified some broad approaches to these issues. Addressing the emerging issues identified in our horizon scan will further increase the contribution of the world zoo and aquarium community to global biodiversity conservation. © 2014 Wiley Periodicals, Inc.

Horizon scanning of new and emerging medical technology in Australia: its relevance to Medical Services Advisory Committee health technology assessments and public funding.

PubMed

O'Malley, Sue P; Jordan, Ernest

2009-07-01

In 1998, a formal process using full health technology assessments (HTAs) was implemented to determine the suitability for public subsidy of new and emerging medical technologies in the Australian private healthcare sector. This process is overseen by the Medical Services Advisory Committee (MSAC). In 2004, horizon scanning was introduced in Australia with the stated objective of identifying new and emerging medical technologies into the public healthcare sector, with consideration to the publicly subsidized private healthcare sector. How well horizon scanning works in identifying new and emerging technologies suitable for government subsidized funding in the private healthcare sector is examined in this study. A descriptive evaluation of the impact of horizon scanning as an early alert and awareness system identifying new and emerging technologies before these technologies are submitted to MSAC for a full HTA. All MSAC HTAs commenced after the introduction of horizon scanning in 2004 were cross-checked with the list of Prioritizing Summaries or Horizon Scanning Reports to determine whether a prior Prioritizing Summary or Horizon Scanning Report had been carried out. Of the forty-three technologies that were the subject of a full MSAC HTAs in the time period examined, only eleven had been the subject of either a Prioritizing Summary or Horizon Scanning Report. As a result of a full MSAC HTA, twelve of the technologies that were not the subject of a Prioritizing Summary or Horizon Scanning Report were given positive recommendations for public funding. Horizon scanning was set up to scan the introduction of new and emerging medical technologies into the public healthcare sector, with consideration to the publicly subsidized private healthcare sector. Based on the number of new and emerging technologies that have been the subject of a full MSAC HTA without first being subjected to either a Prioritizing Summary or Horizon Scanning Report, horizon scanning in Australia

Horizons at Brooklyn Friends School: How a Public-Private Partnership Creates Equity and Opportunity in Downtown Brooklyn

ERIC Educational Resources Information Center

Johnson, Kamauru

2016-01-01

The building that houses Brooklyn Friends School's (New York) preschool, lower, and middle divisions stands on a quiet one-way street in an otherwise bustling downtown Brooklyn business district. After most students head home for the day, others come to the school to participate in the Horizons Program. The Horizons Program at Brooklyn Friends…

Observation of an optical event horizon in a silicon-on-insulator photonic wire waveguide.

PubMed

Ciret, Charles; Leo, François; Kuyken, Bart; Roelkens, Gunther; Gorza, Simon-Pierre

2016-01-11

We report on the first experimental observation of an optical analogue of an event horizon in integrated nanophotonic waveguides, through the reflection of a continuous wave on an intense pulse. The experiment is performed in a dispersion-engineered silicon-on-insulator waveguide. In this medium, solitons do not suffer from Raman induced self-frequency shift as in silica fibers, a feature that is interesting for potential applications of optical event horizons. As shown by simulations, this also allows the observation of multiple reflections at the same time on fundamental solitons ejected by soliton fission.

Expanding Horizons--Developing the Next Generation of International Professionals

ERIC Educational Resources Information Center

Barry, Tania; Garcia-Febo, Loida

2012-01-01

Today's global library village includes overseas collaboration between colleagues in various continents seeking to provide effective forums for new librarians. This paper features lessons learned as well as recommendations for colleagues undertaking events involving international collaboration. These are based on the authors' experiences whilst…

Expanding Horizons and Unresolved Conundrums: Language Testing and Assessment

ERIC Educational Resources Information Center

Leung, Constant; Lewkowicz, Jo

2006-01-01

Since the last "TESOL Quarterly" commemorative issue 15 years ago, there have been too many important developments in language testing and assessment for all of them to be discussed in a single article. Therefore, this article focuses on issues that we believe are integrally linked to pedagogic and curriculum concerns of English language teaching.…

Expanding the horizons of soil science to the public

NASA Astrophysics Data System (ADS)

Lindbo, David L.; Hopmans, Jan; Olson, Carolyn; Fisk, Susan; Chapman, Susan

2015-04-01

Soils are critical to all life on the planet yet most individuals treat soil like dirt. As soil scientist we have long recognized this and have struggled to find ways to communicate the importance of soils to the public. The goal is not purely altruistic as we recognize that society funds or research and provides the workforce in soils that we need to continue to gain knowledge and expertise in soil science. In 2006 the Soil Science Society of America took a bold move and created its K12 Committee in part to compliment the Dig It! The Secrets of Soil exhibit that opened in July 2008 at the Smithsonian's Institution's Nation Museum of Natural History (of which SSS was a founding sponsor). The committee's work began quickly with a website designed to provide resources for K12 teachers (primary and school teachers). The first accomplishments included reviewing and posting links to web based information already available to teachers. These links were sorted by subject and grade level to make it easier for teachers to navigate the web and find what they needed quickly. Several presentations and lessons designed for K12 teachers were also posted at this time. Concurrent with this effort a subcommittee review and organized the national teaching standards to show where soils could fit into the overall K12 curriculum. As the website was being developed another subcommittee developed a soils book (Soil! Get the Inside Scoop, 2008) to further compliment the Dig It! exhibit. This was a new endeavor for SSSA having never worked with the non-academic audience in developing a book. Peer-reviews of this book included not only scientist but also students in order to make sure the book was attractive to them. Once the book was published and the website developed it became clear more outreach was needed. SSSA K12 Committee has attended both the National Science Teachers Association (since 2008) the USA Science and Engineering Festival (since 2010) with exhibits and workshops. It has cooperated and contributed to the American Geologic Institutes' Earth Science Week materials with brochures and lesson plans and with National Association of Conservation Districts by providing peer-review and distribution of materials. The most recent developments from the committee include a web redesign that is more student and teacher friendly, the development of a peer-review system to publish K12 Lesson Plans, and finally the publication of a new soils book (Know Soils, Know Life, 2012) for the 8-12th grade audience. It is hoped that Know Soils, Know Life will be used by the Cannon Envirothon and environmental science students and teachers. Future activities planned include a state soils book, teacher's guide for Know Soils, Know Life and development of a searchable digital photo/video library. Overall this committee has been exceedingly productive in its brief 8 year history. Most recently and in part based on the success of the K12 Committee's success, SSSA created an Identity Committee with the goal of not only reaching our members and other related scientist but also to better engage the public and the media. The efforts of this committee have been to redesign our web site to make it more accessible to the general public. The opening page has interest of a general nature and links that some who knows nothing (or very little) about soils can navigate to find out more. Prominent on this home page are links to soil questions posed by the public and answered by soil scientists. There is also a soil related blog as well as a resource for soil photos. In order to encourage secondary school students to consider a career involving soils there are profiles of individuals who are researchers, consultants, teachers and artists as well as soil scientists. The hope is that all this information will inspire a new generation of soil scientist as well as help the general public understand that soil is not just dirt.

Dust Measurements by the Student Dust Counter (SDC) onboard the New Horizons Mission

NASA Astrophysics Data System (ADS)

James, David; Horanyi, Mihaly; Poppe, Andrew

The Venetia Burney Student Dust Counter (VSDC) on the New Horizons spacecraft is a dust impact detector designed to map the interplanetary dust distribution along the trajectory of the New Horizons spacecraft as it traverses our solar system. VSDC is the first student built instrument on a deep space mission and is currently operated by a small group of undergraduate and graduate students at the Laboratory for Atmospheric and Space Physics (LASP), University of Colorado. VSDC is based on permanently polarized thin plastic film sensors that generate an electrical signal when an impacting dust particle penetrates them. The total surface area is about 0.1 square meters and the detection threshold is about 1 micron in radius. By the time of this meeting (7/2008), VSDC will have operated for about 500 days, covering an approximate distance of 1.2 to 10.5 AU. In this talk, we will briefly review the VSDC instrument, including the in-flight calibrations and tests. We will report on the measured spatial and size distribution of interplanetary dust particles before and after the New Horizons encounter with Jupiter. These data will also be compared to earlier measurements by Ulysses, Galileo and Cassini.

New horizons mapping of Europa and Ganymede.

PubMed

Grundy, W M; Buratti, B J; Cheng, A F; Emery, J P; Lunsford, A; McKinnon, W B; Moore, J M; Newman, S F; Olkin, C B; Reuter, D C; Schenk, P M; Spencer, J R; Stern, S A; Throop, H B; Weaver, H A

2007-10-12

The New Horizons spacecraft observed Jupiter's icy satellites Europa and Ganymede during its flyby in February and March 2007 at visible and infrared wavelengths. Infrared spectral images map H2O ice absorption and hydrated contaminants, bolstering the case for an exogenous source of Europa's "non-ice" surface material and filling large gaps in compositional maps of Ganymede's Jupiter-facing hemisphere. Visual wavelength images of Europa extend knowledge of its global pattern of arcuate troughs and show that its surface scatters light more isotropically than other icy satellites.

The Rim and the Ancient Mariner: The Nautical Horizon Affects Postural Sway in Older Adults

PubMed Central

Wade, Michael G.; Stergiou, Nick

2016-01-01

On land, the spatial magnitude of postural sway (i.e., the amount of sway) tends to be greater when participants look at the horizon than when they look at nearby targets. By contrast, on ships at sea, the spatial magnitude of postural sway in young adults has been greater when looking at nearby targets and less when looking at the horizon. Healthy aging is associated with changes in the movement patterns of the standing body sway, and these changes typically are interpreted in terms of age-related declines in the ability to control posture. To further elucidate the mechanisms associated with these changes we investigated control of posture in a setting that poses substantial postural challenges; standing on a ship at sea. In particular, we explored postural sway on a ship at sea when older adults looked at the horizon or at nearby targets. We evaluated the kinematics of the center of pressure in terms of spatial magnitude (i.e., the amount of sway) and multifractality (a measure of temporal dynamics). We found that looking at the horizon significantly affected the multifractality of standing body, but did not systematically influence the spatial magnitude of sway. We discuss the results in terms of age-related changes in the perception and control of dynamic body orientation. PMID:27973576

Simulating Surface Oil Transport During the Deepwater Horizon Oil Spill: Experiments with the BioCast System

DTIC Science & Technology

2014-01-25

Virtual Special Issue Gulf of Mexico Modelling – Lessons from the spill Simulating surface oil transport during the Deepwater Horizon oil spill ...ocean surface materials. The Deepwater Horizon oil spill in the Gulf of Mexico provided a test case for the Bio-Optical Forecasting (BioCast) system...addition of explicit sources and sinks of surface oil concentrations provides a framework for increasingly complex oil spill modeling efforts that extend

Analysis of Over-the-Horizon Tactical Communications in an Immature Theater

DTIC Science & Technology

2014-06-13

frequency bands, capacity, costs, and mobility, the research examines both alternate portions of the electromagnetic spectrum and rising technologies...IMMATURE THEATER, by Major Samuel Eugene Sinclair, 75 pages. This qualitative research in the field of over-the-horizon (OTH) voice communications

How Big Is the Earth? A Calculation beyond Your Horizon

ERIC Educational Resources Information Center

Kibble, Bob

2011-01-01

A consequence of the curvature of the Earth is that distant ships apparently disappear over the horizon. This article shows how you can use a simple photograph to help students obtain a reasonable estimate of the size of the Earth using little more than the mathematics of Pythagoras. (Contains 5 figures.)

BAYESIAN TECHNIQUES FOR COMPARING TIME-DEPENDENT GRMHD SIMULATIONS TO VARIABLE EVENT HORIZON TELESCOPE OBSERVATIONS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kim, Junhan; Marrone, Daniel P.; Chan, Chi-Kwan

2016-12-01

The Event Horizon Telescope (EHT) is a millimeter-wavelength, very-long-baseline interferometry (VLBI) experiment that is capable of observing black holes with horizon-scale resolution. Early observations have revealed variable horizon-scale emission in the Galactic Center black hole, Sagittarius A* (Sgr A*). Comparing such observations to time-dependent general relativistic magnetohydrodynamic (GRMHD) simulations requires statistical tools that explicitly consider the variability in both the data and the models. We develop here a Bayesian method to compare time-resolved simulation images to variable VLBI data, in order to infer model parameters and perform model comparisons. We use mock EHT data based on GRMHD simulations to explore themore » robustness of this Bayesian method and contrast it to approaches that do not consider the effects of variability. We find that time-independent models lead to offset values of the inferred parameters with artificially reduced uncertainties. Moreover, neglecting the variability in the data and the models often leads to erroneous model selections. We finally apply our method to the early EHT data on Sgr A*.« less

Horizon scanning for emergence of new viruses: from constructing complex scenarios to online games.

PubMed

Gale, P; Breed, A C

2013-10-01

Horizon scanning techniques can be developed to identify novel routes and sources for the emergence of viruses in the medium to long term. Central to horizon scanning is prediction of the complex scenarios through which viruses could emerge before they occur. One approach involves 'spidergrams' in which complex scenarios are generated by combining factors randomly selected from different categories of events. Spidergrams provide a framework for how different factors could interact, irrespective of the virus, and also enable testing of combinations not previously considered but which would be 'tested' in nature by a virus. The emergence of viruses through new routes is often related to changes, for example, in environmental and social factors, and the Internet will undoubtedly be used to identify long-term trends for consideration. In addition, online games may provide horizon scanners with suggestions for new routes and strategies that could be used by emerging viruses. © 2012 Crown copyright Reproduced with the permission of the Controller of Her Majesty's Stationery Office and Animal Health and Veterinary Laboratories Agency.

Bayesian Techniques for Comparing Time-dependent GRMHD Simulations to Variable Event Horizon Telescope Observations

NASA Astrophysics Data System (ADS)

Kim, Junhan; Marrone, Daniel P.; Chan, Chi-Kwan; Medeiros, Lia; Özel, Feryal; Psaltis, Dimitrios

2016-12-01

The Event Horizon Telescope (EHT) is a millimeter-wavelength, very-long-baseline interferometry (VLBI) experiment that is capable of observing black holes with horizon-scale resolution. Early observations have revealed variable horizon-scale emission in the Galactic Center black hole, Sagittarius A* (Sgr A*). Comparing such observations to time-dependent general relativistic magnetohydrodynamic (GRMHD) simulations requires statistical tools that explicitly consider the variability in both the data and the models. We develop here a Bayesian method to compare time-resolved simulation images to variable VLBI data, in order to infer model parameters and perform model comparisons. We use mock EHT data based on GRMHD simulations to explore the robustness of this Bayesian method and contrast it to approaches that do not consider the effects of variability. We find that time-independent models lead to offset values of the inferred parameters with artificially reduced uncertainties. Moreover, neglecting the variability in the data and the models often leads to erroneous model selections. We finally apply our method to the early EHT data on Sgr A*.

The solar occultation technique for remote sensing of particulates in the earth's atmosphere. I - The inversion of horizon radiances from space

NASA Technical Reports Server (NTRS)

Schuerman, D. W.; Giovane, F.; Greenberg, J. M.

1976-01-01

The aerosol scattering coefficient as a function of height can be recovered from a direct inversion of the single-scattering horizon radiance provided the sun is above the horizon and an independent measurement of extinction as a function of height is made. Aerosol detection is effected by means of spacecraft measurements of the horizon radiance made during periods of spacecraft twilight. A solar occultation technique which allows the twilight measurements to be made when the sun is still above the horizon greatly reduces the complexity of the inversion problem. The second part of the paper reports on the use of a coronograph aboard Skylab to photograph the horizon just before spacecraft twilight in order to monitor the aerosol component above the tropopause. The coronograph picture, centered on 26.5 degrees E longitude and 63.0 degrees S latitude, shows that the aerosol layer peaks at a height of 48 plus or minus 1 km.

Silicon microfabricated beam expander

NASA Astrophysics Data System (ADS)

Othman, A.; Ibrahim, M. N.; Hamzah, I. H.; Sulaiman, A. A.; Ain, M. F.

2015-03-01

The feasibility design and development methods of silicon microfabricated beam expander are described. Silicon bulk micromachining fabrication technology is used in producing features of the structure. A high-precision complex 3-D shape of the expander can be formed by exploiting the predictable anisotropic wet etching characteristics of single-crystal silicon in aqueous Potassium-Hydroxide (KOH) solution. The beam-expander consist of two elements, a micromachined silicon reflector chamber and micro-Fresnel zone plate. The micro-Fresnel element is patterned using lithographic methods. The reflector chamber element has a depth of 40 µm, a diameter of 15 mm and gold-coated surfaces. The impact on the depth, diameter of the chamber and absorption for improved performance are discussed.

Radio Occultation Measurements of Pluto's Atmosphere with New Horizons

NASA Astrophysics Data System (ADS)

Hinson, D. P.; Linscott, I.; Tyler, G. L.; Bird, M. K.; Paetzold, M.; Strobel, D. F.; Summers, M. E.; Woods, W. W.; Stern, A.; Weaver, H. A., Jr.; Olkin, C.; Young, L. A.; Ennico Smith, K.; Gladstone, R.; Greathouse, T.; Kammer, J.; Parker, A. H.; Parker, J. W.; Retherford, K. D.; Schindhelm, E.; Singer, K. N.; Steffl, A.; Tsang, C.; Versteeg, M.

2015-12-01

The reconnaissance of the Pluto System by New Horizons included radio occultations at both Pluto and Charon. This talk will present the latest results from the Pluto occultation. The REX instrument onboard New Horizons received and recorded uplink signals from two 70-m antennas and two 34-m antennas of the NASA Deep Space Network - each transmitting 20 kW at 4.2-cm wavelength - during a diametric occultation by Pluto. At the time this was written only a short segment of data at occultation entry (193°E, 17°S) was available for analysis. The REX measurements extend unequivocally to the surface, providing the first direct measure of the surface pressure and the temperature structure in Pluto's lower atmosphere. Preliminary analysis yields a surface pressure of about 10 microbars, smaller than expected. Data from occultation exit (16°E, 15°N) are scheduled to arrive on the ground in late August 2015. Those observations will yield an improved estimate of the surface pressure, a second temperature profile, and a measure of the diameter of Pluto with a precision of a few hundred meters.

Tracking responses to the 2010 Deepwater Horizon oil spill using trace elements in molluscan shells and tissues

NASA Astrophysics Data System (ADS)

Roopnarine, P. D.; Anderson, L.; Roopnarine, D.; Gillikin, D. P.; Goodwin, D.

2010-12-01

Documenting the effects of modern stressors on coastal benthic marine communities requires a combination of baseline historical data and modern dynamic data. E.g., landfall of hydrocarbons from the 2010 Deepwater Horizon rig and well explosion in the Gulf of Mexico is impacting coastal areas long affected by natural seepage, as well as petroleum exploration and development. In Louisiana, exploration in coastal areas that began in the 1920s expanded greatly with the development of the first mobile drilling barge in 1933. In total nearly 50,000 wells have been drilled in the Gulf of Mexico since the 1930s. Given this historical context, we are assessing pathways and rates at which crude oil components from the 2010 spill are incorporated into northern Gulf of Mexico coastal food webs. Sclerochronological techniques are being used to unlock the high-resolution physical and chemical records preserved within mollusc shells. We are analyzing historical specimens collected from the late 19th through late 20th centuries, baseline specimens collected in May 2010 in Louisiana and Alabama before visible hydrocarbons were present, and specimens collected in August 2010 after hydrocarbons made landfall. We are examining changes in life history traits (growth rate, recruitment, mortality, reproduction) of the commercial oyster Crassostrea virginica, and other common, co-occurring molluscs that are primary and secondary consumers in Gulf of Mexico coastal food webs. The taxa include the marsh-dwelling gastropod Littoraria irrorata and mussel Geukensia demissa, and open-water species including the bivalves Ischadium recurvum and Tellina alternata. These consumers range from epifaunal, sessile, filter feeders; to infaunal, mobile, deposit feeders; to epifaunal, mobile, omnivorous grazers. In this way, multiple potential pathways into coastal food webs are being monitored. Because environmental perturbations of many scales are recorded by the accretionary growth of mollusc shells

A unified picture of cosmological entropy on apparent horizon in F(R, G) gravity

NASA Astrophysics Data System (ADS)

Keskin, Ali Ihsan; Acikgoz, Irfan

2017-10-01

In this study, the validity of the generalized second law of thermodynamics (GSLT) has been investigated in F(R, G) gravity. We consider that the boundary of the universe is surrounded by an apparent horizon in the spatially flat Friedmann-Robertson-Walker (FRW) universe, and we take into account the Hawking temperature on the horizons. The unified solutions of the field equations corresponding to gravity theory have been applied to the validity of the GSLT frame, and in this way, both the solutions have been verified and all the expansion history of the universe has been shown in a unified picture.

Mission Support of the New Horizons 2014 MU69 Encounter via Stellar Occultations

NASA Astrophysics Data System (ADS)

Young, Eliot

The Kuiper belt object 2014 MU69 is the targeted flyby candidate for the New Horizons spacecraft's extended mission, with a close flyby on 1 January 2019. MU69 is thought to be a cold classical Kuiper belt object; it would be the first of these objects to be resolved and studied by a spacecraft. Based on an apparent V-magnitude of 27, the diameter of 2014 MU69 is thought to be between 20 50 km. New Horizons is on track to fly by it on 1-JAN-2019. SOFIA is well-suited to determine or better constrain the size, shape and albedo of this object by observing three bright occultations in 2017. These occultations will also search for dangerous rings (such as those around Chariklo) and provide improved astrometry supporting New Horizons. During the summer of 2017, MU69 will occult stars with V-magnitudes of 15.5, 15.6 and 13.1 on June 3, July 10 and July 17 respectively. Observations with the FPI+ and HIPO photometers at 20 Hz will resolve occultation chord lengths at the few 100-m level, with signal-to-noise ratios of 111.9 and 19.2 per timestep for the 13.1 and 15.5-magnitude stars, respectively. 2014 MU69 would be the smallest known member of the KBO population with a well-known size; as such, its albedo (and the inferred presence or lack of surface frosts) would be a key data point with respect to its impact and accretion history. Knowing the size and albedo 18 months before the New Horizons encounter will be a critical aid in optimizing the flyby observing sequences as well as enabling more precise targeting of the encounter by refining MU69's astrometry and orbit solution. Further, finding rings would constitute an early detection of a significant hazard to the spacecraft.

3 CFR 13543 - Executive Order 13543 of May 21, 2010. National Commission on the BP Deepwater Horizon Oil Spill...

Code of Federal Regulations, 2011 CFR

2011-01-01

... Commission on the BP Deepwater Horizon Oil Spill and Offshore Drilling 13543 Order 13543 Presidential... Deepwater Horizon Oil Spill and Offshore Drilling By the authority vested in me as President by the... applicable to offshore drilling that would ensure effective oversight, monitoring, and response capabilities...

Advanced expander test bed program

NASA Technical Reports Server (NTRS)

Riccardi, D. P.; Mitchell, J. C.

1993-01-01

The Advanced Expander Test Bed (AETB) is a key element in NASA's Space Chemical Engine Technology Program for development and demonstration of expander cycle oxygen/hydrogen engine and advanced component technologies applicable to space engines as well as launch vehicle upper stage engines. The AETB will be used to validate the high-pressure expander cycle concept, investigate system interactions, and conduct investigations of advanced mission focused components and new health monitoring techniques in an engine system environment. The split expander cycle AETB will operate at combustion chamber pressures up to 1200 psia with propellant flow rates equivalent to 20,000 lbf vacuum thrust. Contract work began 27 Apr. 1990. During 1992, a major milestone was achieved with the review of the final design of the oxidizer turbopump in Sep. 1992.

Molecular Identification of Ectomycorrhizal Mycelium in Soil Horizons

PubMed Central

Landeweert, Renske; Leeflang, Paula; Kuyper, Thom W.; Hoffland, Ellis; Rosling, Anna; Wernars, Karel; Smit, Eric

2003-01-01

Molecular identification techniques based on total DNA extraction provide a unique tool for identification of mycelium in soil. Using molecular identification techniques, the ectomycorrhizal (EM) fungal community under coniferous vegetation was analyzed. Soil samples were taken at different depths from four horizons of a podzol profile. A basidiomycete-specific primer pair (ITS1F-ITS4B) was used to amplify fungal internal transcribed spacer (ITS) sequences from total DNA extracts of the soil horizons. Amplified basidiomycete DNA was cloned and sequenced, and a selection of the obtained clones was analyzed phylogenetically. Based on sequence similarity, the fungal clone sequences were sorted into 25 different fungal groups, or operational taxonomic units (OTUs). Out of 25 basidiomycete OTUs, 7 OTUs showed high nucleotide homology (≥99%) with known EM fungal sequences and 16 were found exclusively in the mineral soil. The taxonomic positions of six OTUs remained unclear. OTU sequences were compared to sequences from morphotyped EM root tips collected from the same sites. Of the 25 OTUs, 10 OTUs had ≥98% sequence similarity with these EM root tip sequences. The present study demonstrates the use of molecular techniques to identify EM hyphae in various soil types. This approach differs from the conventional method of EM root tip identification and provides a novel approach to examine EM fungal communities in soil. PMID:12514012

Horizon structure of rotating Einstein-Born-Infeld black holes and shadow

NASA Astrophysics Data System (ADS)

Atamurotov, Farruh; Ghosh, Sushant G.; Ahmedov, Bobomurat

2016-05-01

We investigate the horizon structure of the rotating Einstein-Born-Infeld solution which goes over to the Einstein-Maxwell's Kerr-Newman solution as the Born-Infeld parameter goes to infinity (β → ∞). We find that for a given β , mass M, and charge Q, there exist a critical spinning parameter aE and rHE, which corresponds to an extremal Einstein-Born-Infeld black hole with degenerate horizons, and aE decreases and rHE increases with increase of the Born-Infeld parameter β , while ahorizons. Similarly, the effect of β on the infinite redshift surface and in turn on the ergo-region is also included. It is well known that a black hole can cast a shadow as an optical appearance due to its strong gravitational field. We also investigate the shadow cast by the both static and rotating Einstein-Born-Infeld black hole and demonstrate that the null geodesic equations can be integrated, which allows us to investigate the shadow cast by a black hole which is found to be a dark zone covered by a circle. Interestingly, the shadow of an Einstein-Born-Infeld black hole is slightly smaller than for the Reissner-Nordstrom black hole, which consists of concentric circles, for different values of the Born-Infeld parameter β , whose radius decreases with increase of the value of the parameter β . Finally, we have studied observable distortion parameter for shadow of the rotating Einstein-Born-Infeld black hole.

Horizon in random matrix theory, the Hawking radiation, and flow of cold atoms.

PubMed

Franchini, Fabio; Kravtsov, Vladimir E

2009-10-16

We propose a Gaussian scalar field theory in a curved 2D metric with an event horizon as the low-energy effective theory for a weakly confined, invariant random matrix ensemble (RME). The presence of an event horizon naturally generates a bath of Hawking radiation, which introduces a finite temperature in the model in a nontrivial way. A similar mapping with a gravitational analogue model has been constructed for a Bose-Einstein condensate (BEC) pushed to flow at a velocity higher than its speed of sound, with Hawking radiation as sound waves propagating over the cold atoms. Our work suggests a threefold connection between a moving BEC system, black-hole physics and unconventional RMEs with possible experimental applications.

A 2018 Horizon Scan of Emerging Issues for Global Conservation and Biological Diversity.

PubMed

Sutherland, William J; Butchart, Stuart H M; Connor, Ben; Culshaw, Caroline; Dicks, Lynn V; Dinsdale, Jason; Doran, Helen; Entwistle, Abigail C; Fleishman, Erica; Gibbons, David W; Jiang, Zhigang; Keim, Brandon; Roux, Xavier Le; Lickorish, Fiona A; Markillie, Paul; Monk, Kathryn A; Mortimer, Diana; Pearce-Higgins, James W; Peck, Lloyd S; Pretty, Jules; Seymour, Colleen L; Spalding, Mark D; Tonneijck, Femke H; Gleave, Rosalind A

2018-01-01

This is our ninth annual horizon scan to identify emerging issues that we believe could affect global biological diversity, natural capital and ecosystem services, and conservation efforts. Our diverse and international team, with expertise in horizon scanning, science communication, as well as conservation science, practice, and policy, reviewed 117 potential issues. We identified the 15 that may have the greatest positive or negative effects but are not yet well recognised by the global conservation community. Themes among these topics include new mechanisms driving the emergence and geographic expansion of diseases, innovative biotechnologies, reassessments of global change, and the development of strategic infrastructure to facilitate global economic priorities. Copyright © 2017 Elsevier Ltd. All rights reserved.

The universal character of Zwanziger's horizon function in Euclidean Yang-Mills theories

NASA Astrophysics Data System (ADS)

Capri, M. A. L.; Dudal, D.; Guimaraes, M. S.; Pereira, A. D.; Mintz, B. W.; Palhares, L. F.; Sorella, S. P.

2018-06-01

In light of the recently established BRST invariant formulation of the Gribov-Zwanziger theory, we show that Zwanziger's horizon function displays a universal character. More precisely, the correlation functions of local BRST invariant operators evaluated with the Yang-Mills action supplemented with a BRST invariant version of the Zwanziger's horizon function and quantized in an arbitrary class of covariant, color invariant and renormalizable gauges which reduce to the Landau gauge when all gauge parameters are set to zero, have a unique, gauge parameters independent result, corresponding to that of the Landau gauge when the restriction to the Gribov region Ω in the latter gauge is imposed. As such, thanks to the BRST invariance, the cut-off at the Gribov region Ω acquires a gauge independent meaning in the class of the physical correlators.

Exchangeable hydrogen explains the pH of spodosol Oa horizons

USGS Publications Warehouse

Ross, D.S.; David, M.B.; Lawrence, G.B.; Bartlett, R.J.

1996-01-01

The chemistry of extremely acid Oa horizons does not conform to traditional pH, Al, and base saturation relationships. Results from two separate studies of northeastern U.S. forested soils were used to investigate relationships between pH in water or dilute salt solutions and other soil characteristics. In Oa horizons with pH below 4, soil pH in dilute CaCl2 solution was correlated with exchangeable H+ measured either by titration (r = -0.88, P = 0.0001, n = 142) or by electrode (r = -0.89, P = 0.0001, n = 45). Exchangeable H+ expressed as a percentage of the cation-exchange capacity (CEC) was linear with pH and showed similar slopes for data from both studies. For all samples, pHw = 4.21 - 1.80 x H+/CEC (R2 = 0.69, n = 194). The reciprocal of the H+/CEC ratio is base saturation with Al added to the bases. Because of the low pH, exchangeable Al does not appear to behave as an acid. Exchangeable H+ remains an operationally defined quantity because of the difficulty in separating exchange and hydrolysis reactions. In a variety of neutral-salt extractants, concentration of H+ were correlated with 0.1 M BaCl2-exchangeable H+ (r > 0.91, P = 0.0001, n = 26) regardless of the strength of the extract. Nine successive extractions with 0.33 mM CaCl2 removed more H+ than was removed by single batch extractions with either 1 M KCl or 0.1 M BaCl2 (average H+ of 70, 43, and 49 mmol kg-1, respectively for 26 samples). The data showed little difference in the chemical behavior of Oa horizons from a variety of geographical sites and vegetation types.

DOM composition and transformation in boreal forest soils: The effects of temperature and organic-horizon decomposition state

USGS Publications Warehouse

O’Donnell, Jonathan A.; Aiken, George R.; Butler, Kenna D.; Guillemette, Francois; Podgorski, David C.; Spencer, Robert G. M.

2016-01-01

The boreal region stores large amounts of organic carbon (C) in organic-soil horizons, which are vulnerable to destabilization via warming and disturbance. Decomposition of soil organic matter (SOM) contributes to the production and turnover of dissolved organic matter (DOM). While temperature is a primary control on rates of SOM and DOM cycling, little is known about temperature effects on DOM composition in soil leachate. Here we conducted a 30 day incubation to examine the effects of temperature (20 versus 5°C) and SOM decomposition state (moss versus fibric versus amorphous horizons) on DOM composition in organic soils of interior Alaska. We characterized DOM using bulk dissolved organic C (DOC) concentration, chemical fractionation, optical properties, and ultrahigh-resolution mass spectrometry. We observed an increase in DOC concentration and DOM aromaticity in the 20°C treatment compared to the 5°C treatment. Leachate from fibric horizons had higher DOC concentration than shallow moss or deep amorphous horizons. We also observed chemical shifts in DOM leachate over time, including increases in hydrophobic organic acids, polyphenols, and condensed aromatics and decreases in low-molecular weight hydrophilic compounds and aliphatics. We compared ultrahigh-resolution mass spectrometry and optical data and observed strong correlations between polyphenols, condensed aromatics, SUVA254, and humic-like fluorescence intensities. These findings suggest that biolabile DOM was preferentially mineralized, and the magnitude of this transformation was determined by kinetics (i.e., temperature) and substrate quality (i.e., soil horizon). With future warming, our findings indicate that organic soils may release higher concentrations of aromatic DOM to aquatic ecosystems.