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
Horizons versus singularities in spherically symmetric space-times
Bronnikov, K. A.; Elizalde, E.; Odintsov, S. D.; Zaslavskii, O. B.
2008-09-15
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 matter 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.
The WSMR Timing System: Toward New Horizons
NASA Technical Reports Server (NTRS)
Gilbert, William A.; Stimets, Bob
1996-01-01
In 1991, White Sands Missile Range (WSMR) initiated a modernization program for its range timing system. The main focus of this modernization program was to develop a system that was highly accurate, easy to maintain, and portable. The logical decision at the time was to develop a system based solely on Global Positioning System (GPS) technology. Since that time, wsmr has changed its philosophy on how GPS would be utilized for the timing system. This paper will describe WSMR's initial modernization plans for its range timing system and how certain events have led to a modification of these plans.
Time Horizons, Discounting, and Intertemporal Choice
ERIC Educational Resources Information Center
Streich, Philip; Levy, Jack S.
2007-01-01
Although many decisions involve a stream of payoffs over time, political scientists have given little attention to how actors make the required tradeoffs between present and future payoffs, other than applying the standard exponential discounting model from economics. After summarizing the basic discounting model, we identify some of its leading…
NASA Astrophysics Data System (ADS)
Goddéris, Y.; Brantley, S. L.; François, L. M.; Schott, J.; Pollard, D.; Déqué, M.; Dury, M.
2013-01-01
Quantifying how C fluxes will change in the future is a complex task for models because of the coupling between climate, hydrology, and biogeochemical reactions. Here we investigate how pedogenesis of the Peoria loess, which has been weathering for the last 13 kyr, will respond over the next 100 yr of climate change. Using a cascade of numerical models for climate (ARPEGE), vegetation (CARAIB) and weathering (WITCH), we explore the effect of an increase in CO2 of 315 ppmv (1950) to 700 ppmv (2100 projection). The increasing CO2 results in an increase in temperature along the entire transect. In contrast, drainage increases slightly for a focus pedon in the south but decreases strongly in the north. These two variables largely determine the behavior of weathering. In addition, although CO2 production rate increases in the soils in response to global warming, the rate of diffusion back to the atmosphere also increases, maintaining a roughly constant or even decreasing CO2 concentration in the soil gas phase. Our simulations predict that temperature increasing in the next 100 yr causes the weathering rates of the silicates to increase into the future. In contrast, the weathering rate of dolomite - which consumes most of the CO2 - decreases in both end members (south and north) of the transect due to its retrograde solubility. We thus infer slower rates of advance of the dolomite reaction front into the subsurface, and faster rates of advance of the silicate reaction front. However, additional simulations for 9 pedons located along the north-south transect show that the dolomite weathering advance rate will increase in the central part of the Mississippi Valley, owing to a maximum in the response of vertical drainage to the ongoing climate change. The carbonate reaction front can be likened to a terrestrial lysocline because it represents a depth interval over which carbonate dissolution rates increase drastically. However, in contrast to the lower pH and shallower
NASA Astrophysics Data System (ADS)
Goddéris, Y.; Brantley, S. L.; François, L. M.; Schott, J.; Pollard, D.; Déqué, M.
2012-08-01
Quantifying how C fluxes will change in the future is a complex task for models because of the coupling between climate, hydrology, and biogeochemical reactions. Here we investigate how pedogenesis of the Peoria loess, which has been weathering for the last 13 kyr, will respond over the next 100 yr of climate change. Using a cascade of numerical models for climate (ARPEGE), vegetation (CARAIB) and weathering (WITCH) we explore the effect of an increase in CO2 of 315 ppmv (1950) to 700 ppmv (2100 projection). The increasing CO2 results in an increase in temperature along the entire transect. In contrast, drainage increases slightly for a focus pedon in the South but decreases strongly in the North. These two variables largely determine the behavior of weathering. In addition, although CO2 production rate increases in the soils in response to global warming, the rate of diffusion back to the atmosphere also increases, maintaining a roughly constant or even decreasing CO2 concentration in the soil gas phase. Our simulations predict that temperature increasing in the next 100 yr causes the weathering rates of the silicates to increase into the future. In contrast, the weathering rate of dolomite - which consumes most of the CO2-decreases due to its retrograde solubility in both end members (South and North) of the transect. We thus infer slower rates of advance of the dolomite reaction front into the subsurface, and faster rates of advance of the silicate reaction front. However, additional simulations for 9 pedons located along the North-South transect show that dolomite weathering will increase in the central part of the Mississippi Valley, owing to a maximum in the response of vertical drainage to the ongoing climate change. The carbonate reaction front can be likened to a terrestrial lysocline because it represents a depth interval over which carbonate dissolution rates increase drastically. However, in contrast to the lower pH and shallower lysocline expected in
Time machines with the compactly determined Cauchy horizon
NASA Astrophysics Data System (ADS)
Krasnikov, S.
2014-07-01
The building of a time machine, if possible at all, requires the relevant regions of spacetime to be compact (that is, physically speaking, free from sources of unpredictability such as infinities and singularities). Motivated by this argument we consider the spacetimes with the compactly determined Cauchy horizons (CDCHs), the defining property of which is the compactness of J-(U) ¯∩J+(S0), where U is an open subset of the Cauchy horizon and S0 is a Cauchy surface of the initial globally hyperbolic region Min. The following two facts are established: (1) Min has no globally hyperbolic maximal extension. This means that, by shaping appropriately a precompact portion of a globally hyperbolic region, one can force the Universe to produce either a closed causal curve, or a quasiregular singularity, whichever it abhors less. (2) Before a CDCH is formed a null geodesic appears which infinitely approaches the horizon returning again and again in the same—arbitrarily small—region. The energy of the photon moving on such a geodesic increases with each passage, or at least falls insufficiently fast. As a result, an observer located in the mentioned region would see a bunch of photons passing through his laboratory with the arbitrarily large total energy. We speculate that this phenomenon may have observable consequences.
NASA Astrophysics Data System (ADS)
Rosen, Michael R.; Arehart, Greg B.; Lico, Michael S.
2004-05-01
Large tufa mounds (>3 m tall, with a basal circumference of 5 m) have been discovered on the margin of Big Soda Lake, Nevada, USA. These tufa mounds are rooted at a maximum of 4 m below the current lake surface and are actively forming from groundwater seepage, which can be seen emanating from the top of the tufa mounds. Big Soda Lake is a volcanic crater lake whose water level is maintained exclusively by groundwater. The age of the tufa mounds is well constrained because prior to the development of the Newlands Irrigation Project in 1907, the water level was ˜18 m lower than the current lake level. The vertical columnar nature of the tufa mounds indicates that they formed under the lake and not subaerially. Thus, the tufa mounds are <100 yr old and have grown at a rate ≥30 mm/yr. Stable oxygen and carbon isotope analyses of tufa carbonate compared to isotopic analyses of groundwater and lake water and hydrochemical data indicate that the fluids responsible for their precipitation are a simple mixture of modern groundwater and lake water and do not reflect a recent climate signature. The exceptionally fast growth of the tufa mounds indicates that large tufa deposits may form almost instantaneously in geologic time. Given this potential for rapid growth and the fact that variations in isotopic compositions of tufa deposits have been interpreted in terms of changes in paleoclimate and changes in the composition of recharge water over thousands of years, care should be taken when trying to determine the significance of variations in isotopic or chemical compositions of tufas that may have been caused by mixing with groundwater.
Rosen, Michael R.; Arehart, G.B.; Lico, M.S.
2004-01-01
Large tufa mounds (>3 m tall, with a basal circumference of 5 m) have been discovered on the margin of Big Soda Lake, Nevada, USA. These tufa mounds are rooted at a maximum of 4 m below the current lake surface and are actively forming from groundwater seepage, which can be seen emanating from the top of the tufa mounds. Big Soda Lake is a volcanic crater lake whose water level is maintained exclusively by groundwater. The age of the tufa mounds is well constrained because prior to the development of the Newlands Irrigation Project in 1907, the water level was ???18 m lower than the current lake level. The vertical columnar nature of the tufa mounds indicates that they formed under the lake and not subaerially. Thus, the tufa mounds are <100 yr old and have grown at a rate ???30 mm/yr. Stable oxygen and carbon isotope analyses of tufa carbonate compared to isotopic analyses of groundwater and lake water and hydrochemical data indicate that the fluids responsible for their precipitation are a simple mixture of modern groundwater and lake water and do not reflect a recent climate signature. The exceptionally fast growth of the tufa mounds indicates that large tufa deposits may form almost instantaneously in geologic time. Given this potential for rapid growth and the fact that variations in isotopic compositions of tufa deposits have been interpreted in terms of changes in paleoclimate and changes in the composition of recharge water over thousands of years, care should be taken when trying to determine the significance of variations in isotopic or chemical compositions of tufas that may have been caused by mixing with groundwater. ?? 2004 Geological Society of America.
Age, Time, and Decision Making: From Processing Speed to Global Time Horizons
Löckenhoff, Corinna E.
2013-01-01
Time and time perceptions are integral to decision making because any meaningful choice is embedded in a temporal context and requires the evaluation of future preferences and outcomes. The present review examines the influence of chronological age on time perceptions and horizons and discusses implications for decision making across the life span. Time influences and interacts with decision making in multiple ways. Specifically, this review examines the following topic areas: (1) processing speed and decision time, (2) internal clocks and time estimation, (3) mental representations of future time and intertemporal choice, and (4) global time horizons. For each aspect, patterns of age differences and implications for decision strategies and quality are discussed. The conclusion proposes frameworks to integrate different lines of research and identifies promising avenues for future inquiry. PMID:22023567
Deepwater Horizon - Estimating surface oil volume distribution in real time
NASA Astrophysics Data System (ADS)
Lehr, B.; Simecek-Beatty, D.; Leifer, I.
2011-12-01
Spill responders to the Deepwater Horizon (DWH) oil spill required both the relative spatial distribution and total oil volume of the surface oil. The former was needed on a daily basis to plan and direct local surface recovery and treatment operations. The latter was needed less frequently to provide information for strategic response planning. Unfortunately, the standard spill observation methods were inadequate for an oil spill this size, and new, experimental, methods, were not ready to meet the operational demands of near real-time results. Traditional surface oil estimation tools for large spills include satellite-based sensors to define the spatial extent (but not thickness) of the oil, complemented with trained observers in small aircraft, sometimes supplemented by active or passive remote sensing equipment, to determine surface percent coverage of the 'thick' part of the slick, where the vast majority of the surface oil exists. These tools were also applied to DWH in the early days of the spill but the shear size of the spill prevented synoptic information of the surface slick through the use small aircraft. Also, satellite images of the spill, while large in number, varied considerably in image quality, requiring skilled interpretation of them to identify oil and eliminate false positives. Qualified staff to perform this task were soon in short supply. However, large spills are often events that overcome organizational inertia to the use of new technology. Two prime examples in DWH were the application of hyper-spectral scans from a high-altitude aircraft and more traditional fixed-wing aircraft using multi-spectral scans processed by use of a neural network to determine, respectively, absolute or relative oil thickness. But, with new technology, come new challenges. The hyper-spectral instrument required special viewing conditions that were not present on a daily basis and analysis infrastructure to process the data that was not available at the command
Federal Register 2010, 2011, 2012, 2013, 2014
2010-12-21
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Federal Register 2010, 2011, 2012, 2013, 2014
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An integral equation representation approach for valuing Russian options with a finite time horizon
NASA Astrophysics Data System (ADS)
Jeon, Junkee; Han, Heejae; Kim, Hyeonuk; Kang, Myungjoo
2016-07-01
In this paper, we first describe a general solution for the inhomogeneous Black-Scholes partial differential equation with mixed boundary conditions using Mellin transform techniques. Since Russian options with a finite time horizon are usually formulated into the inhomogeneous free-boundary Black-Scholes partial differential equation with a mixed boundary condition, we apply our method to Russian options and derive an integral equation satisfied by Russian options with a finite time horizon. Furthermore, we present some numerical solutions and plots of the integral equation using recursive integration methods and demonstrate the computational accuracy and efficiency of our method compared to other competing approaches.
Horizons and non-local time evolution of quantum mechanical systems
NASA Astrophysics Data System (ADS)
Casadio, Roberto
2015-04-01
According to general relativity, trapping surfaces and horizons are classical causal structures that arise in systems with sharply defined energy and corresponding gravitational radius. The latter concept can be extended to a quantum mechanical matter state simply by means of the spectral decomposition, which allows one to define an associated "horizon wave-function". Since this auxiliary wave-function contains crucial information about the causal structure of space-time, a new proposal is formulated for the time evolution of quantum systems in order to account for the fundamental classical property that outer observers cannot receive signals from inside a horizon. The simple case of a massive free particle at rest is used throughout the paper as a toy model to illustrate the main ideas.
Parisian ruin over a finite-time horizon
NASA Astrophysics Data System (ADS)
Dębicki, Krzysztof; Hashorva, Enkelejd; Ji, LanPeng
2016-03-01
For a risk process $R_u(t)=u+ct-X(t), t\\ge 0$, where $u\\ge 0$ is the initial capital, $c>0$ is the premium rate and $X(t),t\\ge 0$ is an aggregate claim process, we investigate the probability of the Parisian ruin \\[ \\mathcal{P}_S(u,T_u)=\\mathbb{P}\\{\\inf_{t\\in[0,S]} \\sup_{s\\in[t,t+T_u]} R_u(s)<0\\}, \\] with a given positive constant $S$ and a positive measurable function $T_u$. We derive asymptotic expansion of $\\mathcal{P}_S(u,T_u)$, as $u\\to\\infty$, for the aggregate claim process $X$ modeled by Gaussian processes. As a by-product, we derive the exact tail asymptotics of the infimum of a standard Brownian motion with drift over a finite-time interval.
Real-time beyond the horizon vessel detection
NASA Astrophysics Data System (ADS)
Roarty, Hugh J.; Smith, Michael; Glenn, Scott M.; Barrick, Donald E.
2013-05-01
The marine transportation system (MTS) is a vital component of the United States Economy. Waterborne cargo accounts for more than $742 billion of the nation's economy and creates employment for 13 million citizens. A disruption in this system would have far reaching consequences to the security of the country. The US National High Frequency radar network, which comprises 130 radar stations around the country, became operational in May 2009. It provides hourly measurements of surface currents to the US Coast Guard for search and rescue (SAR). This system has the capability of being a dual use system providing information for environmental monitoring as well as vessel position information for maritime security. Real time vessel detection has been implemented at two of the radar stations outside New York Harbor. Several experiments were conducted to see the amount vessel traffic that the radar could capture. The radars were able to detect a majority of the vessels that are reporting via the Automatic Identification System (AIS) as well as 30 percent of mid to large size vessels that are not reporting via AIS. The radars were able to detect vessels out to 60 km from the coast. The addition of a vessel detection capability to the National HF radar network will provide valuable information to maritime security sector. This dual use capability will fill a gap in the current surveillance of US coastal waters. It will also provide longer-range situational awareness necessary to detect and track smaller size vessels in the large vessel clutter.
World-sheet stability, space-time horizons and cosmic censorship
NASA Astrophysics Data System (ADS)
Pollock, M. D.
2014-11-01
Previously, we have analyzed the stability and supersymmetry of the heterotic superstring world sheet in the background Friedmann space-time generated by a perfect fluid with energy density ρ and pressure p = ( γ - 1) ρ. The world sheet is tachyon-free within the range 2/3 ≤ γ ≤ ∞, and globally supersymmetric in the Minkowski-space limit ρ = ∞, or when γ = 2/3, which is the equation of state for stringy matter and corresponds to the Milne universe, that expands along its apparent horizon. Here, this result is discussed in greater detail, particularly with regard to the question of horizon structure, cosmic censorship, the TCP theorem, and local world-sheet supersymmetry. Also, we consider the symmetric background space-time generated by a static, electrically (or magnetically) charged matter distribution of total mass and charge Q, and containing a radially directed macroscopic string. We find that the effective string mass m satisfies the inequality m 2 ≥ 0, signifying stability, provided that , which corresponds to the Reissner-Nordström black hole. The case of marginal string stability, m 2 = 0, is the extremal solution , which was shown by Gibbons and Hull to be supersymmetric, and has a marginal horizon. If , the horizon disappears, m 2 < 0, and the string becomes unstable.
Forecasting geomagnetic activity at monthly and annual horizons: Time series models
NASA Astrophysics Data System (ADS)
Reikard, Gordon
2015-10-01
Most of the existing work on forecasting geomagnetic activity has been over short intervals, on the order of hours or days. However, it is also of interest to predict over longer horizons, ranging from months to years. Forecasting tests are run for the Aa index, which begins in 1868 and provides the longest continuous records of geomagnetic activity. This series is challenging to forecast. While it exhibits cycles at 11-22 years, the amplitude and period of the cycles varies over time. There is also evidence of discontinuous trending: the slope and direction of the trend change repeatedly. Further, at the monthly resolution, the data exhibits nonlinear variability, with intermittent large outliers. Several types of models are tested: regressions, neural networks, a frequency domain algorithm, and combined models. Forecasting tests are run at horizons of 1-11 years using the annual data, and 1-12 months using the monthly data. At the 1-year horizon, the mean errors are in the range of 13-17 percent while the median errors are in the range of 10-14 percent. The accuracy of the models deteriorates at longer horizons. At 5 years, the mean errors lie in the range of 21-23 percent, and at 11 years, 23-25 percent. At the 1 year horizon, the most accurate forecast is achieved by a combined model, but over longer horizons (2-11 years), the neural net dominates. At the monthly resolution, the mean errors are in the range of 17-19 percent at 1 month, while the median errors lie in a range of 14-17 percent. The mean error increases to 23-24 percent at 5 months, and 25 percent at 12 months. A model combining frequency and time domain methods is marginally better than regressions and neural networks alone, up to 11 months. The main conclusion is that geomagnetic activity can only be predicted to within a limited threshold of accuracy, over a given range of horizons. This is consistent with the finding of irregular trends and cycles in the annual data and nonlinear variability in
Continuous-Time Mean-Variance Portfolio Selection with Random Horizon
Yu, Zhiyong
2013-12-15
This paper examines the continuous-time mean-variance optimal portfolio selection problem with random market parameters and random time horizon. Treating this problem as a linearly constrained stochastic linear-quadratic optimal control problem, I explicitly derive the efficient portfolios and efficient frontier in closed forms based on the solutions of two backward stochastic differential equations. Some related issues such as a minimum variance portfolio and a mutual fund theorem are also addressed. All the results are markedly different from those in the problem with deterministic exit time. A key part of my analysis involves proving the global solvability of a stochastic Riccati equation, which is interesting in its own right.
Larry G. Stolarczyk, Sc.D.
2002-07-31
Real-time horizon sensing (HS) on continuous mining (CM) machines is becoming an industry tool. Installation and testing of production-grade HS systems has been ongoing this quarter at Oxbow Mining Company, Monterey Coal Company (EXXON), FMC Trona, Twentymile Coal Company (RAG America), and SASOL Coal. Detailed monitoring of system function, user experience, and mining benefits is ongoing. All horizon sensor components have finished MSHA (United States) and IEC (International) certification.
Chatterjee, Bishu; Sharp, Peter A.
2006-07-15
Electric transmission and other rate cases use a form of the discounted cash flow model with a single long-term growth rate to estimate rates of return on equity. It cannot incorporate information about the appropriate time horizon for which analysts' estimates of earnings growth have predictive powers. Only a non-constant growth model can explicitly recognize the importance of the time horizon in an ROE calculation. (author)
Mean-Variance Hedging on Uncertain Time Horizon in a Market with a Jump
Kharroubi, Idris; Lim, Thomas; Ngoupeyou, Armand
2013-12-15
In this work, we study the problem of mean-variance hedging with a random horizon T∧τ, where T is a deterministic constant and τ is a jump time of the underlying asset price process. We first formulate this problem as a stochastic control problem and relate it to a system of BSDEs with a jump. We then provide a verification theorem which gives the optimal strategy for the mean-variance hedging using the solution of the previous system of BSDEs. Finally, we prove that this system of BSDEs admits a solution via a decomposition approach coming from filtration enlargement theory.
Optimal Consumption in a Brownian Model with Absorption and Finite Time Horizon
Grandits, Peter
2013-04-15
We construct {epsilon}-optimal strategies for the following control problem: Maximize E[{integral}{sub [0,{tau})}e{sup -{beta}s} dC{sub s}+e{sup -{beta}{tau}}X{sub {tau}}] , where X{sub t}=x+{mu}t+{sigma}W{sub t}-C{sub t}, {tau}{identical_to}inf{l_brace}t>0|X{sub t}=0{r_brace} Logical-And T, T>0 is a fixed finite time horizon, W{sub t} is standard Brownian motion, {mu}, {sigma} are constants, and C{sub t} describes accumulated consumption until time t. It is shown that {epsilon}-optimal strategies are given by barrier strategies with time-dependent barriers.
NASA Astrophysics Data System (ADS)
Franzè, Giuseppe; Lucia, Walter; Tedesco, Francesco
2014-12-01
This paper proposes a Model Predictive Control (MPC) strategy to address regulation problems for constrained polytopic Linear Parameter Varying (LPV) systems subject to input and state constraints in which both plant measurements and command signals in the loop are sent through communication channels subject to time-varying delays (Networked Control System (NCS)). The results here proposed represent a significant extension to the LPV framework of a recent Receding Horizon Control (RHC) scheme developed for the so-called robust case. By exploiting the parameter availability, the pre-computed sequences of one- step controllable sets inner approximations are less conservative than the robust counterpart. The resulting framework guarantees asymptotic stability and constraints fulfilment regardless of plant uncertainties and time-delay occurrences. Finally, experimental results on a laboratory two-tank test-bed show the effectiveness of the proposed approach.
MARKOV: A methodology for the solution of infinite time horizon MARKOV decision processes
Williams, B.K.
1988-01-01
Algorithms are described for determining optimal policies for finite state, finite action, infinite discrete time horizon Markov decision processes. Both value-improvement and policy-improvement techniques are used in the algorithms. Computing procedures are also described. The algorithms are appropriate for processes that are either finite or infinite, deterministic or stochastic, discounted or undiscounted, in any meaningful combination of these features. Computing procedures are described in terms of initial data processing, bound improvements, process reduction, and testing and solution. Application of the methodology is illustrated with an example involving natural resource management. Management implications of certain hypothesized relationships between mallard survival and harvest rates are addressed by applying the optimality procedures to mallard population models.
Pluto's Atmosphere at the Time of the New Horizons Flyby from the 29-JUN-2015 Occultation
NASA Astrophysics Data System (ADS)
Young, E.; Skrutskie, M.; Wasserman, L.; Howell, R.; Young, L.; Olkin, C.; Buie, M.
2015-10-01
Pluto is expected to occult a star on 29-JUN-2015, only two weeks before the scheduled New Horizons flyby on Pluto on 14-JUL-2015. This occultation should be remarkable for several reasons in addition to its synergy with the spacecraft observations. First, the occulted star is by far the brightest ever to be observed in a Pluto occultation: its V-mag is 12.10 ± 0.03, about ten times brighter than Pluto itself. We are deploying a wide array of telescopes to obtain quality lightcurves at 10 Hz, sufficient to resolve vertical atmospheric structure (e.g., gravity waves) at the 2.5-km scale over a range of radii from about 1195 to 1300 km. Second, we plan to obtain lighcurves in infrared wavelengths near 1.7 μm, where the star's H-mag (about 11) is bright enough to provide useful signal-to-noise ratios, albeit at slower cadences near 1 Hz (about two points per scale height). The combination of simultaneous IR and visible wavelength lightcurves should address the decades-old question: is there haze in Pluto's atmosphere, and if so, what is its opacity? New Horizons should image haze layers in reflected light as the occultation quantifies haze extinction in transmitted light: the combination could potentially let us solve for haze phase functions. Third, the current predicted shadow path is centered over much of New Zealand. We plan to deploy three portable telescopes in New Zealand to locations that are candidates for observing central flashes. If successful, these lightcurves can tell us (a) the oblateness of Pluto's atmosphere and (b) the detailed density gradient profile at radii near 1215 km, which (in turn) is a function of trace abundances of CO and CH4 a few tens of km above Pluto's surface. We will report on lightcurves obtained on 29-JUN- 2015, the column abundance of Pluto's atmosphere just two weeks before the New Horizons flyby, the detection (or not) of haze, and - if central flashes are obtained - the oblateness of Pluto's atmosphere.
Larry G. Stolarczyk
2003-03-18
program began development in 1998 and experienced three major design phases. The final version, termed HS-3, was commissioned in 2000 with the assistance of the DOE-Mining Industry of the Future program, commercialized in 2002, and has been used 14 times in 12 different mines within the United States. The Horizon Sensor has applications in both underground and surface mining operations. This technology is primarily used in the coal industry, but is also used to mine trona and potash. All horizon sensor components have Mine Safety and Health Administration (MSHA) (United States) and IEC (International) certification. Horizon Sensing saves energy by maximizing cutting efficiency, cutting only desired material. This desired material is cleaner fuel, therefore reducing pollutants to the atmosphere when burned and burning more efficiently. Extracting only desired material increases productivity by reducing or eliminating the cleaning step after extraction. Additionally, this technology allows for deeper mining, resulting in more material gained from one location. The remote sensing tool allows workers to operate the machinery away from the hazards of cutting coal, including noise, breathing dust and gases, and coal and rock splintering and outbursts. The HS program has primarily revolved around the development of the technology. However, the end goal of the program has always been the commercialization of the technology and only within the last 2 years of the program has this goal been realized. Real-time horizon sensing on mining machines is becoming an industry tool. Detailed monitoring of system function, user experience, and mining benefits is ongoing.
''Illusion of control'' in Time-Horizon Minority and Parrondo Games
NASA Astrophysics Data System (ADS)
Satinover, J. B.; Sornette, D.
2007-12-01
Human beings like to believe they are in control of their destiny. This ubiquitous trait seems to increase motivation and persistence, and is probably evolutionarily adaptive [J.D. Taylor, S.E. Brown, Psych. Bull. 103, 193 (1988); A. Bandura, Self-efficacy: the exercise of control (WH Freeman, New York, 1997)]. But how good really is our ability to control? How successful is our track record in these areas? There is little understanding of when and under what circumstances we may over-estimate [E. Langer, J. Pers. Soc. Psych. 7, 185 (1975)] or even lose our ability to control and optimize outcomes, especially when they are the result of aggregations of individual optimization processes. Here, we demonstrate analytically using the theory of Markov Chains and by numerical simulations in two classes of games, the Time-Horizon Minority Game [M.L. Hart, P. Jefferies, N.F. Johnson, Phys. A 311, 275 (2002)] and the Parrondo Game [J.M.R. Parrondo, G.P. Harmer, D. Abbott, Phys. Rev. Lett. 85, 5226 (2000); J.M.R. Parrondo, How to cheat a bad mathematician (ISI, Italy, 1996)], that agents who optimize their strategy based on past information may actually perform worse than non-optimizing agents. In other words, low-entropy (more informative) strategies under-perform high-entropy (or random) strategies. This provides a precise definition of the “illusion of control” in certain set-ups a priori defined to emphasize the importance of optimization.
NASA Astrophysics Data System (ADS)
Öztaş, A. M.; Smith, M. L.
2015-05-01
Several relationships describing the distance versus time dependence of the cosmic horizon (Rh) for an expanding universe have been published within the past two decades. Some are based on the special conditions, including a flat universe geometry, and when applied for calculation return significantly different values. We present our derivation beginning with Newtonian world then following the Friedmann model from the viewpoint of an observer located at the origin of an expanding spherical, homogeneously matter-dominated universe; both geometrically flat and allowing space-time curvature. Our derivations for the cosmic horizon at the speed of light allow examination for the effects of matter density and space-time curvature. We also compare the fitness of several current models, including the recently proposed Rh = ct universe against the demands of the 580 Union 2.1 Type Ia supernovae distance and redshift data with uncommon, proper attention paid to data transformation and observational errors.
GOM Deepwater Horizon Oil Spill: A Time Series Analysis of Variations in Spilled Hydrocarbons
NASA Astrophysics Data System (ADS)
Palomo, C. M.; Yan, B.
2013-12-01
An estimated amount of 210 million gallons of crude oil was released into the Gulf of Mexico (GOM) from April 20th to July 15th 2010 during the Deepwater Horizon oil rig explosion. The spill caused a tremendous financial, ecological, environmental and health impact and continues to affect the GOM today. Variations in hydrocarbons including alkanes, hopanes and poly-cyclic aromatic hydrocarbons (PAHs) can be analyzed to better understand the oil spill and assist in oil source identification. Twenty-one sediment samples*, two tar ball samples and one surface water oil sample were obtained from distinct locations in the GOM and within varying time frames from May to December 2010. Each sample was extracted through the ASE 200 solvent extractor, concentrated down under nitrogen gas, purified through an alumina column, concentrated down again with nitrogen gas and analyzed via GC X GC-TOF MS. Forty-one different hydrocarbons were quantified in each sample. Various hydrocarbon 'fingerprints,' such as parental :alkylate PAH ratios, high molecular weight PAHs: low molecular weight alkane ratios, and carbon preference index were calculated. The initial objective of this project was to identify the relative hydrocarbon contributions of petrogenic sources and combustion sources. Based on the calculated ratios, it is evident that the sediment core taken in October of 2010 was greatly affected by combustion sources. Following the first month of the spill, oil in the gulf was burned in attempts to contain the spill. Combustion related sources have quicker sedimentation rates, and hydrocarbons from a combustion source essentially move into deeper depths quicker than those from a petrogenic source, as was observed in analyses of the October 2010 sediment. *Of the twenty-one sediment samples prepared, nine were quantified for this project.
Cypryańska, Marzena; Krejtz, Izabela; Jaskółowska, Aleksandra; Kulawik, Alicja; Żukowska, Aleksandra; De Zavala, Agnieszka Golec; Niewiarowski, Jakub; Nezlek, John B
2014-12-01
Compared to younger adults, older adults attend more to positive stimuli, a positivity effect. Older adults have limited time horizons, and they focus on maintaining positive affect, whereas younger adults have unlimited time horizons, and they focus on acquiring knowledge and developing skills. Time horizons were manipulated by asking participants (66 young adults, M age = 20.5 yr., SD = 1.2) to think that their lives would end in three years. Some participants focused on what they would do in these three years (life focus), whereas others focused on the fact that they would die in three years (death focus). Attentional biases to facial expressions of happiness, sadness, fear, anger, and disgust were measured. Participants viewed 20 slides including pairings of a happy face with each of the negative emotions. The dependent measure was the relative attention paid to the faces on each slide. Participants in the experimental conditions exhibited a positivity effect compared to participants in the control condition, although some results suggested that this effect was weaker in the death focus condition than in the life focus condition. PMID:25457091
Optimal stock liquidation in a regime switching model with finite time horizon
NASA Astrophysics Data System (ADS)
Pemy, M.; Zhang, Q.
2006-09-01
This paper is concerned with a finite-horizon optimal selling rule. A set of geometric Brownian motions coupled by a finite-state Markov chain is used to characterize stock price movements. Given a fixed transaction fee, the optimal selling rule can be obtained by solving an optimal stopping problem. The corresponding value function is shown to be the unique viscosity solution to the associated HJB equations. Numerical solutions to these equations and their convergence are obtained. A numerical example is presented to illustrate the results.
NASA Astrophysics Data System (ADS)
Borghesi, Christian; Marsili, Matteo; Miccichè, Salvatore
2007-08-01
We investigate the emergence of a structure in the correlation matrix of assets’ returns as the time horizon over which returns are computed increases from the minutes to the daily scale. We analyze data from different stock markets (New York, Paris, London, Milano) and with different methods. In addition to the usual correlations, we also analyze those obtained by subtracting the dynamics of the “center of mass” (i.e., the market mode). We find that when the center of mass is not removed the structure emerges, as the time horizon increases, from splitting a single large cluster into smaller ones. By contrast, when the market mode is removed the structure of correlations observed at the daily scale is already well defined at very high frequency ( 5min in the New York Stock Exchange). Moreover, this structure accounts for 80% of the classification of stocks in economic sectors. Similar results, though less sharp, are found for the other markets. We also find that the structure of correlations in the overnight returns is markedly different from that of intraday activity.
NASA Astrophysics Data System (ADS)
Strobach, Elmar; Harris, B. D.; Dupuis, J. C.; Kepic, A. W.
2014-03-01
The shallow aquifer on the Gnangara Mound, north of Perth, Western Australia, is recharged by winter rainfall. Water infiltrates through a sandy Podosol where cemented accumulation (B-) horizons are common. They are water retentive and may impede recharge. To observe wetting fronts and the influence of soil horizons on unsaturated flow, we deployed time-lapse borehole radar techniques sensitive to soil moisture variations during an annual recharge cycle. Zero-offset crosswell profiling (ZOP) and vertical radar profiling (VRP) measurements were performed at six sites on a monthly basis before, during, and after annual rainfall in 2011. Water content profiles are derived from ZOP logs acquired in closely spaced wells. Sites with small separation between wells present potential repeatability and accuracy difficulties. Such problems could be lessened by (i) ZOP saturated zone velocity matching of time-lapse curves, and (ii) matching of ZOP and VRP results. The moisture contents for the baseline condition and subsequent observations are computed using the Topp relationship. Time-lapse moisture curves reveal characteristic vadose zone infiltration regimes. Examples are (I) full recharge potential after 200 mm rainfall, (II) delayed wetting and impeded recharge, and (III) no recharge below 7 m depth. Seasonal infiltration trends derived from long-term time-lapse neutron logging at several sites are shown to be comparable with infiltration trends recovered from time-lapse crosswell radar measurements. However, radar measurements sample a larger volume of earth while being safer to deploy than the neutron method which employs a radioactive source. For the regime (III) site, where time-lapse radar indicates no net recharge or zero flux to the water table, a simple water balance provides an evapotranspiration value of 620 mm for the study period. This value compares favorably to previous studies at similar test sites in the region. Our six field examples demonstrate
The State of Pluto's Bulk Atmosphere at the Time of the New Horizons Encounter
NASA Astrophysics Data System (ADS)
Resnick, Aaron C.; Barry, T.; Buie, M. W.; Carriazo, C. Y.; Cole, A.; Gault, D.; Giles, B.; Giles, D.; Hartig, K.; Hill, K.; Howell, R. R.; Hudson, G.; Loader, B.; Mackie, J.; Nelson, M.; Olkin, C.; Register, J.; Rodgers, T.; Sicardy, B.; Skrutskie, M.; Verbiscer, A.; Wasserman, L.; Watson, C.; Young, E.; Young, L.; Zalucha, A.
2015-11-01
On 29-JUL-2015, our team - plus many critical amateur astronomers - observed a stellar occultation by Pluto from sites in Australia and New Zealand. This event was remarkable for two reasons: it preceded the New Horizons flyby of Pluto by just two weeks, and the occulted star was about 10x brighter than Pluto itself, by far the brightest Pluto occultation event observed to date. The separation of ground sites spanned nearly 900 km with respect to the central chord, allowing a good geometric solution for the shadow path. The lightcurves show some inflection points and broad "fangs" that are characteristic of perturbations in the temperature profile. Preliminary fits show that the temperature profile derived from a 2006 occultation (Young et al. 2008) reproduces the 29-JUN-2015 lightcurves well. Assuming a surface radius of 1187 km for Pluto, we find that the surface pressure is 18 +/- 3 µbar. This pressure indicates that Pluto's surface has not yet started to cool down, despite a decrease in absorbed solar flux of more than 17% since perihelion in 1988. A surface pressure of 18 µbar would correspond to a nitrogen ice surface temperature of 38.0 K.References:Young, E.F., et al. "Vertical Structure in Pluto's Atmosphere from the 2006 June 12 Stellar Occultation," AJ 136 1757-1769 (2008)
Water Stress on U.S. Power Production at Decadal Time Horizons
NASA Astrophysics Data System (ADS)
Ganguli, P.; Kumar, D.; Yun, J.; Short, G.; Klausner, J.; Ganguly, A. R.
2014-12-01
Thermoelectric power production at risk, owing to current and projected water scarcity and rising stream temperatures, is assessed for the continental United States (US) at decadal scales. Regional water scarcity is driven by climate variability and change, as well as by multi-sector water demand. While a planning horizon of zero to about thirty years is occasionally prescribed by stakeholders, the challenges to risk assessment at these scales include the difficulty in delineating decadal climate trends from intrinsic natural or multiple model variability. Current generation global climate or earth system models are not credible at the spatial resolutions of power plants, especially for surface water quantity and stream temperatures, which further exacerbates the assessment challenge. Population changes, which are anyway difficult to project, cannot serve as adequate proxies for changes in the water demand across sectors. The hypothesis that robust assessments of power production at risks are possible, despite the uncertainties, has been examined as a proof of concept. An approach is presented for delineating water scarcity and temperature from climate models, observations and population storylines, as well as for assessing power production at risk by examining geospatial correlations of power plant locations within regions where the usable water supply for energy production happens to be scarcer and warmer. Acknowledgment: Funding provided by US DOE's ARPA-E through Award DE-AR0000374.
Wang, Fei-Yue; Jin, Ning; Liu, Derong; Wei, Qinglai
2011-01-01
In this paper, we study the finite-horizon optimal control problem for discrete-time nonlinear systems using the adaptive dynamic programming (ADP) approach. The idea is to use an iterative ADP algorithm to obtain the optimal control law which makes the performance index function close to the greatest lower bound of all performance indices within an ε-error bound. The optimal number of control steps can also be obtained by the proposed ADP algorithms. A convergence analysis of the proposed ADP algorithms in terms of performance index function and control policy is made. In order to facilitate the implementation of the iterative ADP algorithms, neural networks are used for approximating the performance index function, computing the optimal control policy, and modeling the nonlinear system. Finally, two simulation examples are employed to illustrate the applicability of the proposed method. PMID:20876014
Zhao, Qiming; Xu, Hao; Jagannathan, Sarangapani
2015-03-01
In this paper, the finite-horizon optimal control design for nonlinear discrete-time systems in affine form is presented. In contrast with the traditional approximate dynamic programming methodology, which requires at least partial knowledge of the system dynamics, in this paper, the complete system dynamics are relaxed utilizing a neural network (NN)-based identifier to learn the control coefficient matrix. The identifier is then used together with the actor-critic-based scheme to learn the time-varying solution, referred to as the value function, of the Hamilton-Jacobi-Bellman (HJB) equation in an online and forward-in-time manner. Since the solution of HJB is time-varying, NNs with constant weights and time-varying activation functions are considered. To properly satisfy the terminal constraint, an additional error term is incorporated in the novel update law such that the terminal constraint error is also minimized over time. Policy and/or value iterations are not needed and the NN weights are updated once a sampling instant. The uniform ultimate boundedness of the closed-loop system is verified by standard Lyapunov stability theory under nonautonomous analysis. Numerical examples are provided to illustrate the effectiveness of the proposed method. PMID:25720005
Time horizons and substance use among African American youths living in disadvantaged urban areas.
Cheong, JeeWon; Tucker, Jalie A; Simpson, Cathy A; Chandler, Susan D
2014-04-01
Transitioning from adolescence to full-fledged adulthood is often challenging, and young people who live in disadvantaged urban neighborhoods face additional obstacles and experience disproportionately higher negative outcomes, including substance abuse and related risk behaviors. This study investigated whether substance use among African Americans ages 15 to 25 (M=18.86 years) living in such areas was related to present-dominated time perspectives and higher delay discounting. Participants (N=344, 110 males, 234 females) living in Deep South disadvantaged urban neighborhoods were recruited using Respondent Driven Sampling, an improved peer-referral sampling method suitable for accessing this hard-to-reach target group. Structured field interviews assessed alcohol, tobacco, and illicit drug use and risk/protective factors, including time perspectives (Zimbardo Time Perspective Inventory [ZTPI]) and behavioral impulsivity (delay discounting task). As predicted, substance use was positively related to a greater ZTPI orientation toward present pleasure and a lower tendency to plan and achieve future goals. Although the sample as a whole showed high discounting of delayed rewards, discount rates did not predict substance use. The findings suggest that interventions to lengthen time perspectives and promote enriched views of future possible selves may prevent and reduce substance use among disadvantaged youths. Discontinuities among the discounting and time perspective variables in relation to substance use merit further investigation. PMID:24531637
Impact of curvature divergences on physical observers in a wormhole space-time with horizons
NASA Astrophysics Data System (ADS)
Olmo, Gonzalo J.; Rubiera-Garcia, D.; Sanchez-Puente, A.
2016-06-01
The impact of curvature divergences on physical observers in a black hole space-time, which, nonetheless, is geodesically complete is investigated. This space-time is an exact solution of certain extensions of general relativity coupled to Maxwell’s electrodynamics and, roughly speaking, consists of two Reissner-Nordström (or Schwarzschild or Minkowski) geometries connected by a spherical wormhole near the center. We find that, despite the existence of infinite tidal forces, causal contact is never lost among the elements making up the observer. This suggests that curvature divergences may not be as pathological as traditionally thought.
Fish, Vincent L.; Doeleman, Sheperd S.; Beaudoin, Christopher; Bolin, David E.; Rogers, Alan E. E.; Blundell, Ray; Gurwell, Mark A.; Moran, James M.; Primiani, Rurik; Bower, Geoffrey C.; Plambeck, Richard; Chamberlin, Richard; Freund, Robert; Friberg, Per; Honma, Mareki; Oyama, Tomoaki; Inoue, Makoto; Krichbaum, Thomas P.; Lamb, James; Marrone, Daniel P.
2011-02-01
Sagittarius A*, the {approx}4 x 10{sup 6} M{sub sun} black hole candidate at the Galactic center, can be studied on Schwarzschild radius scales with (sub)millimeter wavelength very long baseline interferometry (VLBI). We report on 1.3 mm wavelength observations of Sgr A* using a VLBI array consisting of the JCMT on Mauna Kea, the Arizona Radio Observatory's Submillimeter Telescope on Mt. Graham in Arizona, and two telescopes of the CARMA array at Cedar Flat in California. Both Sgr A* and the quasar calibrator 1924-292 were observed over three consecutive nights, and both sources were clearly detected on all baselines. For the first time, we are able to extract 1.3 mm VLBI interferometer phase information on Sgr A* through measurement of closure phase on the triangle of baselines. On the third night of observing, the correlated flux density of Sgr A* on all VLBI baselines increased relative to the first two nights, providing strong evidence for time-variable change on scales of a few Schwarzschild radii. These results suggest that future VLBI observations with greater sensitivity and additional baselines will play a valuable role in determining the structure of emission near the event horizon of Sgr A*.
Killing Horizons Kill Horizon Degrees
NASA Astrophysics Data System (ADS)
Bergamin, L.; Grumiller, D.
Frequently, it is argued that the microstates responsible for the Bekenstein-Hawking entropy should arise from some physical degrees of freedom located near or on the black hole horizon. In this essay, we elucidate that instead entropy may emerge from the conversion of physical degrees of freedom, attached to a generic boundary, into unobservable gauge degrees of freedom attached to the horizon. By constructing the reduced phase space, it can be demonstrated that such a transmutation indeed takes place for a large class of black holes, including Schwarzschild.
The Glacier Peak Tephra: A Continental-Scale Latest Pleistocene Time Horizon
NASA Astrophysics Data System (ADS)
Pyne-O'Donnell, S.; Cwynar, L. C.; Vincent, J. H.; Spear, R.; Froese, D. G.
2014-12-01
The latest Pleistocene eruptions of Glacier Peak in the Cascade Range deposited a widespread set of tephras throughout much of western North America within a short time span where they serve as valuable marker layers for inter-site correlation and chronostratigraphical control. We report the detection of these tephras in microscopic form in three lakes along the Eastern Seaboard (Maine and Nova Scotia). These distinct distal lake layers occur as closely spaced couplets which retain the subtle geochemical variation that characterises the proximal Glacier Peak G and B layers. New radiocarbon dates for the tephras also closely corroborate the most recently revised proximal dates for the tephras (ca. 13,700 - 13,400 cal. yr B.P) which found that they are ca. 400 14C yr older than hitherto thought. Their presence this far eastward implies that their deposition spans the intervening continent (>4000 km) and adds to a developing distal tephrostratigraphical framework with applications to studies of latest Pleistocene deglaciation and environmental change, megafaunal extinction and archaeology.
HORIZON SENSING (PROPOSAL NO.51)
Larry G. Stolarczyk
2003-07-01
Real-time horizon sensing on continuous mining machines is becoming an industry tool. Installation and testing of production-grade Horizon Sensor (HS) systems continued this quarter at Monterey Coal Company (ExxonMobil), Mountain Coal Company West Elk Mine (Arch), and Ohio Valley Coal Company (OVC). Monitoring of system function, user experience, and mining benefits is ongoing. All horizon sensor components have finished MSHA (U.S.) and IEC (International) certification.
HORIZON SENSING (PROPOSAL NO.51)
Larry G. Stolarczyk
2003-07-30
Real-time horizon sensing on continuous mining (CM) machines is becoming an industry tool. Installation and testing of production-grade Horizon Sensor (HS) systems has been ongoing this quarter at Monterey Coal Company (ExxonMobil), Mountain Coal Company West Elk Mine (Arch), Deserado Mining Company (Blue Mountain Energy), and The Ohio Valley Coal Company (TOVCC). Monitoring of system function, user experience, and mining benefits is ongoing. All horizon sensor components have finished MSHA (U.S.) and IEC (International) certification.
NASA Astrophysics Data System (ADS)
Musa, Sarah; Supadi, Siti Suzlin; Omar, Mohd
2014-07-01
Rework is one of the solutions to some of the main issues in reverse logistic and green supply chain as it reduces production cost and environmental problem. Many researchers focus on developing rework model, but to the knowledge of the author, none of them has developed a model for time-varying demand rate. In this paper, we extend previous works and develop multiple batch production system for time-varying demand rate with rework. In this model, the rework is done within the same production cycle.
Taylor-Robinson, David C; Milton, Beth; Lloyd-Williams, Ffion; O'Flaherty, Martin; Capewell, Simon
2008-01-01
Background In order to better understand factors that influence decisions for public health, we undertook a qualitative study to explore issues relating to the time horizons used in decision-making. Methods Qualitative study using semi-structured interviews. 33 individuals involved in the decision making process around coronary heart disease were purposively sampled from the UK National Health Service (national, regional and local levels), academia and voluntary organizations. Analysis was based on the framework method using N-VIVO software. Interviews were transcribed, coded and emergent themes identified. Results Many participants suggested that the timescales for public health decision-making are too short. Commissioners and some practitioners working at the national level particularly felt constrained in terms of planning for the long-term. Furthermore respondents felt that longer term planning was needed to address the wider determinants of health and to achieve societal level changes. Three prominent 'systems' issues were identified as important drivers of short term thinking: the need to demonstrate impact within the 4 year political cycle; the requirement to 'balance the books' within the annual commissioning cycle and the disruption caused by frequent re-organisations within the health service. In addition respondents suggested that the tools and evidence base for longer term planning were not well established. Conclusion Many public health decision and policy makers feel that the timescales for decision-making are too short. Substantial systemic barriers to longer-term planning exist. Policy makers need to look beyond short-term targets and budget cycles to secure investment for long-term improvement in public health. PMID:19094194
NASA Astrophysics Data System (ADS)
MacDonald, I. R.; Garcia-Pineda, O. G.; Solow, A.; Daneshgar, S.; Beet, A.
2013-12-01
Oil discharged as a result of the Deepwater Horizon disaster was detected on the surface of the Gulf of Mexico by synthetic aperture radar satellites from 25 April 2010 until 4 August 2010. SAR images were not restricted by daylight or cloud-cover. Distribution of this material is a tracer for potential environmental impacts and an indicator of impact mitigation due to response efforts and physical forcing factors. We used a texture classifying neural network algorithm for semi-supervised processing of 176 SAR images from the ENVISAT, RADARSAT I, and COSMO-SKYMED satellites. This yielded an estimate the proportion of oil-covered water within the region sampled by each image with a nominal resolution of 10,000 sq m (100m pixels), which was compiled as a 5-km equal area grid covering the northern Gulf of Mexico. Few images covered the entire impact area, so analysis was required to compile a regular time-series of the oil cover. A Gaussian kernel using a bandwidth of 2 d was used to estimate oil cover percent in each grid at noon and midnight throughout the interval. Variance and confidence intervals were calculated for each grid and for the global 12-h totals. Results animated across the impact region show the spread of oil under the influence of physical factors. Oil cover reached an early peak of 17032.26 sq km (sd 460.077) on 18 May, decreasing to 27% of this total on 4 June, following by sharp increase to an overall maximum of 18424.56 sq km (sd 424.726) on 19 June. There was a significant negative correlation between average wind stress and the total area of oil cover throughout the time-series. Correlation between response efforts including aerial and subsurface application of dispersants and burning of gathered oil was negative, positive, or indeterminate at different time segments during the event. Daily totals for oil-covered surface waters of the Gulf of Mexico during 25 April - 9 August 2010 with upper and lower 0.95 confidence limits on estimate. (No oil
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.
HORIZON SENSING (PROPOSAL No.51)
Larry G. Stolarczyk, Sc.D.
2002-04-30
Real-time horizon sensing on continuous mining machines is becoming an industry tool. Installation and testing of production-grade HS systems has been ongoing this quarter at Monterey Coal Company (EXXON), FMC Trona, Twentymile Coal Company (RAG America), and SASOL Coal. Detailed monitoring of system function, user experience, and mining benefits is ongoing. All horizon sensor components have finished MSHA (U.S.) and IEC (International) certification.
Marshall, L G; Pascual, R; Curtis, G H; Drake, R E
1977-03-25
Radiometric (potassium-argon) age determinations for basalts and tuffs associated with middle to late Tertiary mammal-bearing horizons in Patagonia, southern Argentina, permit refinement of boundaries and hiatuses between beds of Deseadan (early Oligocene) through Friasian (middle to late Miocene) age. At two localities beds of Deseadan age are overlain by basalts, which gave dates of 33.6 and 35.4 million years ago; 34.0 million years ago is tentatively accepted as a terminal date for known Deseadan. At several localities beds of Colhuehuapian age are underlain by basalts, which gave dates ranging from 28.8 to 24.3 million years ago; 25.0 million years is tentatively taken as a basal age for known Colhuehuapian. The paleontological hiatus between known Deseadan and known Colhuehuapian is thus in the order of 9.0 million years. Two tuffs from the Santa Cruz Formation (Santacrucian) gave ages of 21.7 and 18.5 million years. Plagioclase and biotite concentrates of an ignimbrite from the Collón Curá Formation (Friasian) gave ages ranging from 15.4 to 14.0 million years. PMID:17738414
NASA Astrophysics Data System (ADS)
Sicardy, B.; Talbot, J.; Meza, E.; Camargo, J. I. B.; Desmars, J.; Gault, D.; Herald, D.; Kerr, S.; Pavlov, H.; Braga-Ribas, F.; Assafin, M.; Benedetti-Rossi, G.; Dias-Oliveira, A.; Gomes-Júnior, A. R.; Vieira-Martins, R.; Bérard, D.; Kervella, P.; Lecacheux, J.; Lellouch, E.; Beisker, W.; Dunham, D.; Jelínek, M.; Duffard, R.; Ortiz, J. L.; Castro-Tirado, A. J.; Cunniffe, R.; Querel, R.; Yock, P. C.; Cole, A. A.; Giles, A. B.; Hill, K. M.; Beaulieu, J. P.; Harnisch, M.; Jansen, R.; Pennell, A.; Todd, S.; Allen, W. H.; Graham, P. B.; Loader, B.; McKay, G.; Milner, J.; Parker, S.; Barry, M. A.; Bradshaw, J.; Broughton, J.; Davis, L.; Devillepoix, H.; Drummond, J.; Field, L.; Forbes, M.; Giles, D.; Glassey, R.; Groom, R.; Hooper, D.; Horvat, R.; Hudson, G.; Idaczyk, R.; Jenke, D.; Lade, B.; Newman, J.; Nosworthy, P.; Purcell, P.; Skilton, P. F.; Streamer, M.; Unwin, M.; Watanabe, H.; White, G. L.; Watson, D.
2016-03-01
We present results from a multi-chord Pluto stellar occultation observed on 2015 June 29 from New Zealand and Australia. This occurred only two weeks before the NASA New Horizons flyby of the Pluto system and serves as a useful comparison between ground-based and space results. We find that Pluto's atmosphere is still expanding, with a significant pressure increase of 5 ± 2% since 2013 and a factor of almost three since 1988. This trend rules out, as of today, an atmospheric collapse associated with Pluto's recession from the Sun. A central flash, a rare occurrence, was observed from several sites in New Zealand. The flash shape and amplitude are compatible with a spherical and transparent atmospheric layer of roughly 3 km in thickness whose base lies at about 4 km above Pluto's surface, and where an average thermal gradient of about 5 K km-1 prevails. We discuss the possibility that small departures between the observed and modeled flash are caused by local topographic features (mountains) along Pluto's limb that block the stellar light. Finally, using two possible temperature profiles, and extrapolating our pressure profile from our deepest accessible level down to the surface, we obtain a possible range of 11.9-13.7 μbar for the surface pressure. Partly based on observations made with the ESO WFI camera at the 2.2 m Telescope (La Silla), under program ID 079.A-9202(A) within the agreement between the ON/MCTI and the Max Planck Society, with the ESO camera NACO at the Very Large Telescope (Paranal), under program ID 089.C-0314(C), and at the Pico dos Dias Observatory/LNA, Brazil.
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.
Xu, Hao; Zhao, Qiming; Jagannathan, Sarangapani
2015-08-01
The output feedback-based near-optimal regulation of uncertain and quantized nonlinear discrete-time systems in affine form with control constraint over finite horizon is addressed in this paper. First, the effect of input constraint is handled using a nonquadratic cost functional. Next, a neural network (NN)-based Luenberger observer is proposed to reconstruct both the system states and the control coefficient matrix so that a separate identifier is not needed. Then, approximate dynamic programming-based actor-critic framework is utilized to approximate the time-varying solution of the Hamilton-Jacobi-Bellman using NNs with constant weights and time-dependent activation functions. A new error term is defined and incorporated in the NN update law so that the terminal constraint error is also minimized over time. Finally, a novel dynamic quantizer for the control inputs with adaptive step size is designed to eliminate the quantization error overtime, thus overcoming the drawback of the traditional uniform quantizer. The proposed scheme functions in a forward-in-time manner without offline training phase. Lyapunov analysis is used to investigate the stability. Simulation results are given to show the effectiveness and feasibility of the proposed method. PMID:25794403
Deepwater Horizon Situation Report #5
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 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 that…
Cope, Michael R; Slack, Tim; Blanchard, Troy C; Lee, Matthew R
2013-05-01
On April 20, 2010, the BP-leased Deepwater Horizon (BP-DH) oil rig exploded, resulting in the largest marine oil spill in history. In this paper we utilize one-of-a-kind household survey data-the Louisiana Community Oil Spill Survey-to examine the impacts of the BP-DH disaster on the mental and physical health of spill affected residents in coastal Louisiana, with a special focus on the influence of community attachment and natural resource employment. We find that levels of both negative mental and physical health were significantly more pronounced at baseline compared to later time points. We show that greater community attachment is linked to lower levels of negative health impacts in the wake of the oil spill and that the disaster had a uniquely negative impact on households involved in the fishing industry. Further, we find evidence that the relationship between community attachment and mental health is more pronounced at later points in time, and that the negative health impacts on fishers have worsened over time. Implications for research and policy are discussed. PMID:23522000
NASA Astrophysics Data System (ADS)
Fountain, Glen H.; Kusnierkiewicz, David Y.; Hersman, Christopher B.; Herder, Timothy S.; Coughlin, Thomas B.; Gibson, William C.; Clancy, Deborah A.; Deboy, Christopher C.; Hill, T. Adrian; Kinnison, James D.; Mehoke, Douglas S.; Ottman, Geffrey K.; Rogers, Gabe D.; Stern, S. Alan; Stratton, James M.; Vernon, Steven R.; Williams, Stephen P.
2008-10-01
The New Horizons spacecraft was launched on 19 January 2006. The spacecraft was designed to provide a platform for seven instruments designated by the science team to collect and return data from Pluto in 2015. The design meets the requirements established by the National Aeronautics and Space Administration (NASA) Announcement of Opportunity AO-OSS-01. The design drew on heritage from previous missions developed at The Johns Hopkins University Applied Physics Laboratory (APL) and other missions such as Ulysses. The trajectory design imposed constraints on mass and structural strength to meet the high launch acceleration consistent with meeting the AO requirement of returning data prior to the year 2020. The spacecraft subsystems were designed to meet tight resource allocations (mass and power) yet provide the necessary control and data handling finesse to support data collection and return when the one-way light time during the Pluto fly-by is 4.5 hours. Missions to the outer regions of the solar system (where the solar irradiance is 1/1000 of the level near the Earth) require a radioisotope thermoelectric generator (RTG) to supply electrical power. One RTG was available for use by New Horizons. To accommodate this constraint, the spacecraft electronics were designed to operate on approximately 200 W. The travel time to Pluto put additional demands on system reliability. Only after a flight time of approximately 10 years would the desired data be collected and returned to Earth. This represents the longest flight duration prior to the return of primary science data for any mission by NASA. The spacecraft system architecture provides sufficient redundancy to meet this requirement with a probability of mission success of greater than 0.85. The spacecraft is now on its way to Pluto, with an arrival date of 14 July 2015. Initial in-flight tests have verified that the spacecraft will meet the design requirements.
Xu, Elvis Genbo; Mager, Edward M; Grosell, Martin; Pasparakis, Christina; Schlenker, Lela S; Stieglitz, John D; Benetti, Daniel; Hazard, E Starr; Courtney, Sean M; Diamante, Graciel; Freitas, Juliane; Hardiman, Gary; Schlenk, Daniel
2016-07-19
The Deepwater Horizon (DWH) oil spill contaminated the spawning habitats for numerous commercially and ecologically important fishes. Exposure to the water accommodated fraction (WAF) of oil from the spill has been shown to cause cardiac toxicity during early developmental stages across fishes. To better understand the molecular events and explore new pathways responsible for toxicity, RNA sequencing was performed in conjunction with physiological and morphological assessments to analyze the time-course (24, 48, and 96 h post fertilization (hpf)) of transcriptional and developmental responses in embryos/larvae of mahi-mahi exposed to WAF of weathered (slick) and source DWH oils. Slick oil exposure induced more pronounced changes in gene expression over time than source oil exposure. Predominant transcriptomic responses included alteration of EIF2 signaling, steroid biosynthesis, ribosome biogenesis and activation of the cytochrome P450 pathway. At 96 hpf, slick oil exposure resulted in significant perturbations in eye development and peripheral nervous system, suggesting novel targets in addition to the heart may be involved in the developmental toxicity of DHW oil. Comparisons of changes of cardiac genes with phenotypic responses were consistent with reduced heart rate and increased pericardial edema in larvae exposed to slick oil but not source oil. PMID:27348429
Semiclassical ultraextremal horizons
Matyjasek, Jerzy; Zaslavskii, O.B.
2005-04-15
We examine backreaction of quantum massive fields on multiply-degenerate (ultraextremal) horizons. It is shown that, under influence of the quantum backreaction, the horizon of such a kind moves to a new position near which the metric does not change its asymptotics, so the ultraextremal black holes and cosmological spacetimes do exist as self-consistent solutions of the semiclassical field equations.
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…
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…
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…
NASA Astrophysics Data System (ADS)
Batic, Davide; Nicolini, Piero
2010-08-01
We study the stability of the noncommutative Schwarzschild black hole interior by analysing the propagation of a massless scalar field between the two horizons. We show that the spacetime fuzziness triggered by the field higher momenta can cure the classical exponential blue-shift divergence, suppressing the emergence of infinite energy density in a region nearby the Cauchy horizon.
NASA Astrophysics Data System (ADS)
Finkelstein, D. B.; Schimmelmann, A.; Rosenheim, B. E.
2012-12-01
We present time-series of bulk hydrocarbon geochemical and compound specific isotopic data of oiled and tarry sediment deposits from Grand Isle and Barataria Bay, Louisiana. Samples were taken between 46 days and 694 days after the Macondo well blowout, and analyzed for bulk hydrocarbon stable carbon and hydrogen isotope ratios, n-alkane and other organic molecular characteristics, ramped pyrolysis stable carbon ratios and radiocarbon content, and compound specific isotope analysis. Bulk and compound specific stable hydrogen isotopes point to slight 2H-enrichment attributable to water washing during transport to Grand Isle and Barataria Bay, followed by more subtle changes after deposition that depended in part on the wave energy available locally. Characterization of the n-alkane distributions through time identified subtle shifts in the dominant n-alkanes from water washing and terrestrial degradation. The loss of high molecular weight n-alkanes and an increase in the unresolved complex mixture after day 337 is consistent with a shift from slight to moderate biodegradation. More significant variations were observed in elemental H:C ratios, whereas bulk stable carbon isotope values showed small increases through time. Ramped pyrolysis analyses illustrated relatively volatile and reactive petroleum-derived components were present during the first year following the spill, but they ultimately became less apparent during later sampling. Isotope results from different ramped pyrolysis components are discussed. Compound specific isotope analysis indicate that a combination of variables (e.g., tidal water washing and biodegradation) may impact degradation during the first 200 days. This period was followed by a mixing of Macondo and non-Macondo hydrocarbons in the environment. In sum, our analyses show the complementary roles of abiotic and biotic factors in degradation of the Deepwater Horizon oil that was deposited in different environments of coastal Louisiana.
NASA Astrophysics Data System (ADS)
Schenk, Paul; Nimmo, Francis
2016-06-01
The New Horizons mission has revealed Pluto and its moon Charon to be geologically active worlds. The familiar, yet exotic, landforms suggest that geologic processes operate similarly across the Solar System, even in its cold outer reaches.
NASA Technical Reports Server (NTRS)
Jalink, A., Jr. (Inventor)
1973-01-01
A precise method and apparatus for locating the earth's infrared horizon from space that is independent of season and latitude is described. First and second integrations of the earth's radiance profile are made from space to earth with the second delayed with respect to the first. The second integration is multiplied by a predetermined constant R and then compared with the first integration. When the two are equal the horizon is located.
Black holes with bottle-shaped horizons
NASA Astrophysics Data System (ADS)
Chen, Yu; Teo, Edward
2016-06-01
We present a new class of four-dimensional AdS black holes with noncompact event horizons of finite area. The event horizons are topologically spheres with one puncture, with the puncture pushed to infinity in the form of a cusp. Because of the shape of their event horizons, we call such black holes "black bottles." The solution was obtained as a special case of the Plebański-Demiański solution, and may describe either static or rotating black bottles. For certain ranges of parameters, an acceleration horizon may also appear in the space-time. We study the full parameter space of the solution, and the various limiting cases that arise. In particular, we show how the rotating black hole recently discovered by Klemm arises as a special limit.
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).
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
Stable predictive control horizons
NASA Astrophysics Data System (ADS)
Estrada, Raúl; Favela, Antonio; Raimondi, Angelo; Nevado, Antonio; Requena, Ricardo; Beltrán-Carbajal, Francisco
2012-04-01
The stability theory of predictive and adaptive predictive control for processes of linear and stable nature is based on the hypothesis of a physically realisable driving desired trajectory (DDT). The formal theoretical verification of this hypothesis is trivial for processes with a stable inverse, but it is not for processes with an unstable inverse. The extended strategy of predictive control was developed with the purpose of overcoming methodologically this stability problem and it has delivered excellent performance and stability in its industrial applications given a suitable choice of the prediction horizon. From a theoretical point of view, the existence of a prediction horizon capable of ensuring stability for processes with an unstable inverse was proven in the literature. However, no analytical solution has been found for the determination of the prediction horizon values which guarantee stability, in spite of the theoretical and practical interest of this matter. This article presents a new method able to determine the set of prediction horizon values which ensure stability under the extended predictive control strategy formulation and a particular performance criterion for the design of the DDT generically used in many industrial applications. The practical application of this method is illustrated by means of simulation examples.
NASA Astrophysics Data System (ADS)
Akcay, Sarp
Boosted black holes play an important role in General Relativity (GR), especially in relation to the binary black hole problem. Solving Einstein vac- uum equations in the strong field regime had long been the holy grail of numerical relativity until the significant breakthroughs made in 2005 and 2006. Numerical relativity plays a crucial role in gravitational wave detection by providing numerically generated gravitational waveforms that help search for actual signatures of gravitational radiation exciting laser interferometric de- tectors such as LIGO, VIRGO and GEO600 here on Earth. Binary black holes orbit each other in an ever tightening adiabatic inspiral caused by energy loss due to gravitational radiation emission. As the orbits shrinks, the holes speed up and eventually move at relativistic speeds in the vicinity of each other (separated by ~ 10M or so where 2M is the Schwarzschild radius). As such, one must abandon the Newtonian notion of a point mass on a circular orbit with tangential velocity and replace it with the concept of black holes, cloaked behind spheroidal event horizons that become distorted due to strong gravity, and further appear distorted because of Lorentz effects from the high orbital velocity. Apparent horizons (AHs) are 2-dimensional boundaries that are trapped surfaces. Conceptually, one can think of them as 'quasi-local' definitions for a black hole horizon. This will be explained in more detail in chapter 2. Apparent horizons are especially important in numerical relativity as they provide a computationally efficient way of describing and locating a black hole horizon. For a stationary spacetime, apparent horizons are 2-dimensional cross-sections of the event horizon, which is itself a 3-dimensional null surface in spacetime. Because an AH is a 2-dimensional cross-section of an event horizon, its area remains invariant under distortions due to Lorentz boosts although its shape changes. This fascinating property of the AH can be
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.
Spacetimes containing slowly evolving horizons
Kavanagh, William; Booth, Ivan
2006-08-15
Slowly evolving horizons are trapping horizons that are ''almost'' isolated horizons. This paper reviews their definition and discusses several spacetimes containing such structures. These include certain Vaidya and Tolman-Bondi solutions as well as (perturbatively) tidally distorted black holes. Taking into account the mass scales and orders of magnitude that arise in these calculations, we conjecture that slowly evolving horizons are the norm rather than the exception in astrophysical processes that involve stellar-scale black holes.
Smooth horizons and quantum ripples
NASA Astrophysics Data System (ADS)
Golovnev, Alexey
2015-05-01
Black holes are unique objects which allow for meaningful theoretical studies of strong gravity and even quantum gravity effects. An infalling and a distant observer would have very different views on the structure of the world. However, a careful analysis has shown that it entails no genuine contradictions for physics, and the paradigm of observer complementarity has been coined. Recently this picture was put into doubt. In particular, it was argued that in old black holes a firewall must form in order to protect the basic principles of quantum mechanics. This AMPS paradox has already been discussed in a vast number of papers with different attitudes and conclusions. Here we want to argue that a possible source of confusion is the neglect of quantum gravity effects. Contrary to widespread perception, it does not necessarily mean that effective field theory is inapplicable in rather smooth neighbourhoods of large black hole horizons. The real offender might be an attempt to consistently use it over the huge distances from the near-horizon zone of old black holes to the early radiation. We give simple estimates to support this viewpoint and show how the Page time and (somewhat more speculative) scrambling time do appear.
On the Bartnik mass of apparent horizons
NASA Astrophysics Data System (ADS)
Mantoulidis, Christos; Schoen, Richard
2015-10-01
In this paper we characterize the intrinsic geometry of apparent horizons (outermost marginally outer trapped surfaces) in asymptotically flat spacetimes; that is, the Riemannian metrics on the two sphere which can arise. Furthermore we determine the minimal ADM mass of a spacetime containing such an apparent horizon. The results are conveniently formulated in terms of the quasi-local mass introduced by Bartnik (1989 Phys. Rev. Lett. 62 2346-8). The Hawking mass provides a lower bound for Bartnik’s quasilocal mass on apparent horizons by way of Penrose’s conjecture on time symmetric slices, proven in 1997 by Huisken and Ilmanen (2001 J. Differ. Geom. 59 353-437) and in full generality in 1999 by Bray (2001 J. Differ. Geom. 59 177-267). We compute Bartnik’s mass for all non-degenerate apparent horizons and show that it coincides with the Hawking mass. As a corollary we disprove a conjecture due to Gibbons in the spirit of Thorne’s hoop conjecture (Gibbons 2009 arXiv:0903.1580), and construct a new large class of examples of apparent horizons with the integral of the negative part of the Gauss curvature arbitrarily large.
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 series of…
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.
Internet's critical path horizon
NASA Astrophysics Data System (ADS)
Valverde, S.; Solé, R. V.
2004-03-01
Internet is known to display a highly heterogeneous structure and complex fluctuations in its traffic dynamics. Congestion seems to be an inevitable result of user's behavior coupled to the network dynamics and it effects should be minimized by choosing appropriate routing strategies. But what are the requirements of routing depth in order to optimize the traffic flow? In this paper we analyse the behavior of Internet traffic with a topologically realistic spatial structure as described in a previous study [S.-H. Yook et al., Proc. Natl Acad. Sci. USA 99, 13382 (2002)]. The model involves self-regulation of packet generation and different levels of routing depth. It is shown that it reproduces the relevant key, statistical features of Internet's traffic. Moreover, we also report the existence of a critical path horizon defining a transition from low-efficient traffic to highly efficient flow. This transition is actually a direct consequence of the web's small world architecture exploited by the routing algorithm. Once routing tables reach the network diameter, the traffic experiences a sudden transition from a low-efficient to a highly-efficient behavior. It is conjectured that routing policies might have spontaneously reached such a compromise in a distributed manner. Internet would thus be operating close to such critical path horizon.
Horizon thermodynamics and spacetime mappings
NASA Astrophysics Data System (ADS)
Faraoni, Valerio; Vitagliano, Vincenzo
2014-03-01
When black holes are dynamical, event horizons are replaced by apparent and trapping horizons. Conformal and Kerr-Schild transformations are widely used in relation to dynamical black holes, and we study the behavior under such transformations of quantities related to the thermodynamics of these horizons, such as the Misner-Sharp-Hernandez mass (internal energy), the Kodama vector, surface gravity, and temperature. The transformation properties are not those expected on the basis of naive arguments.
Transverse deformations of extreme horizons
NASA Astrophysics Data System (ADS)
Li, Carmen; Lucietti, James
2016-04-01
We consider the inverse problem of determining all extreme black hole solutions to the Einstein equations with a prescribed near-horizon geometry. We investigate this problem by considering infinitesimal deformations of the near-horizon geometry along transverse null geodesics. We show that, up to a gauge transformation, the linearised Einstein equations reduce to an elliptic PDE for the extrinsic curvature of a cross-section of the horizon. We deduce that for a given near-horizon geometry there exists a finite dimensional moduli space of infinitesimal transverse deformations. We then establish a uniqueness theorem for transverse deformations of the extreme Kerr horizon. In particular, we prove that the only smooth axisymmetric transverse deformation of the near-horizon geometry of extreme Kerr, such that cross-sections of the horizon are marginally trapped surfaces, corresponds to that of the extreme Kerr black hole. Furthermore, we determine all smooth and biaxisymmetric transverse deformations of the near-horizon geometry of the five-dimensional extreme Myers-Perry black hole with equal angular momenta. We find a three parameter family of solutions such that cross-sections of the horizon are marginally trapped, which is more general than the known black hole solutions. We discuss the possibility that they correspond to new five-dimensional vacuum black holes.
Technologies on the Horizon: Teachers Respond to the Horizon Report
ERIC Educational Resources Information Center
Hodges, Charles B.; Prater, Alyssa H.
2014-01-01
The purpose of this study was to investigate teachers' beliefs regarding the integration of technologies from the 2011 K-12 edition of the "Horizon Report" into their local, public school contexts. Teachers read the "Horizon Report" and then participated in an asynchronous, threaded discussion focusing on technologies they…
Koenderink, Jan
2014-12-20
The problem of "distortionless" viewing with terrestrial telescopic systems (mainly "binoculars") remains problematic. The so called "globe effect" is only partially counteracted in modern designs. Theories addressing the phenomenon have never reached definitive closure. In this paper, we show that exact distortionless viewing with terrestrial telescopic systems is not possible in general, but that it is in principle possible in-very frequent in battle field and marine applications-the case of horizon scanning. However, this involves cylindrical optical elements. For opto-electronic systems, a full solution is more readily feasible. The solution involves a novel interpretation of the relevant constraints and objectives. For final design decisions, it is not necessary to rely on a corpus of psychophysical (or ergonomic) data, although one has to decide whether the instrument is intended as an extension of the eye or as a "pictorial" device. PMID:25608206
Harrison, Sarah; Kachru, Shamit; Wang, Huajia; /Stanford U., ITP /Stanford U., Phys. Dept. /SLAC
2012-04-24
Via the AdS/CFT correspondence, ground states of field theories at finite charge density are mapped to extremal black brane solutions. Studies of simple gravity + matter systems in this context have uncovered wide new classes of extremal geometries. The Lifshitz metrics characterizing field theories with non-trivial dynamical critical exponent z {ne} 1 emerge as one common endpoint in doped holographic toy models. However, the Lifshitz horizon exhibits mildly singular behaviour - while curvature invariants are finite, there are diverging tidal forces. Here we show that in some of the simplest contexts where Lifshitz metrics emerge, Einstein-Maxwell-dilaton theories, generic corrections lead to a replacement of the Lifshitz metric, in the deep infrared, by a re-emergent AdS{sub 2} x R{sup 2} geometry. Thus, at least in these cases, the Lifshitz scaling characterizes the physics over a wide range of energy scales, but the mild singularity is cured by quantum or stringy effects.
Fluctuating black hole horizons
NASA Astrophysics Data System (ADS)
Mei, Jianwei
2013-10-01
In this paper we treat the black hole horizon as a physical boundary to the spacetime and study its dynamics following from the Gibbons-Hawking-York boundary term. Using the Kerr black hole as an example we derive an effective action that describes, in the large wave number limit, a massless Klein-Gordon field living on the average location of the boundary. Complete solutions can be found in the small rotation limit of the black hole. The formulation suggests that the boundary can be treated in the same way as any other matter contributions. In particular, the angular momentum of the boundary matches exactly with that of the black hole, suggesting an interesting possibility that all charges (including the entropy) of the black hole are carried by the boundary. Using this as input, we derive predictions on the Planck scale properties of the boundary.
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 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. 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…
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…
NASA Astrophysics Data System (ADS)
Nelson, S. J.; Johnson, K. B.
2009-12-01
Sampling protocols, including sample timing, collection methods, preservation, and preparation, can strongly influence the results of any analysis. Organic soil horizons are a large pool of mercury (Hg) in most temperate, forested sites; minimizing the potential for under- or over- estimates in this medium is critical for discerning the fate and transport of Hg. Detailed guidance is available for ultra-clean and semi-clean handling for Hg sampling in surface waters. However, neither guidance regarding the proper time of year to sample soils nor methodological studies regarding post-sampling preservation and handling were available in the scientific literature for soil Hg sampling. Here we report on pilot work that (1) provides data for Hg in soils (O-horizon) through an entire year, to determine whether seasonality affects Hg estimates; and (2) documents the effect of treating a soil with acidic water prior to preparation and analysis. We collected O-horizon soil samples monthly from a single plot during 2008, and analyzed them for total Hg. Each month, samples were split; half were ‘control’ samples (dried then analyzed) and half were ‘acidified’ (treated with acidic (pH 2.0) ultrapure water prior to drying and analysis). We observed: (1) a three-fold range of Hg values (148-446 ppb) for the control samples (all collected within the same 2-m2 plot), varying across the twelve months in 2008 during which samples were collected; (2) differences of ~15-20% between acidified and control samples; and, (3) an apparent loss of ~100 ppb of Hg (~22%) if acidification of the dry sample was delayed a day or more. Soils collected when the antecedent period had been wet lost Hg when soils were treated with pH 2.0 solution, potentially because soluble Hg in solution could have been leached during acid treatment. This finding may help to explain why researchers have seen large pulses of Hg in streamwater flux during snowmelt. Further, our results may help to inform
On the differentiability order of horizons
NASA Astrophysics Data System (ADS)
Szeghy, D.
2016-06-01
Let M be a time oriented Lorentzian manifold and H\\subset M a horizon. We will show that the differentiability order of the horizon can change only once along a generator, i.e. the following holds. If γ :I\\to H is a generator, thus, an inextendable past directed light-like geodesic on the horizon, where I=(α ,β ) or [α ,β ), then there exists a unique parameter {t}0\\in [α ,β ] and a positive integer k≥slant 1 such that the following is true. The horizon H is exactly of class {C}k at γ (t), for every t\\in ({t}0,β ), moreover H is only differentiable, but not of class {C}1 at every point γ (t), for which t\\in (α ,{t}0]. Moreover, if γ (α ) is the endpoint of only one generator then for a suitable space-like submanifold R\\subset H the first cut point of R along γ is γ (α ). Furthermore, all the points γ (t), for which t\\in [α ,{t}0], are non-injectivity points of R along γ . Moreover, if H is smooth at an interior point of γ, then H is smooth at every point of γ. MSC 53C50
What happens to Petrov classification, on horizons of axisymmetric dirty black holes
Tanatarov, I. V.; Zaslavskii, O. B.
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. 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.
Social pharmacology: expanding horizons.
Maiti, Rituparna; Alloza, José Luis
2014-01-01
In the current modern and global society, social changes are in constant evolution due to scientific progress (technology, culture, customs, and hygiene) and produce the freedom in individuals to take decisions by themselves or with their doctors toward drug consumption. In the arena of marketed drug products which includes society, individual, administration, and pharmaceutical industry, the young discipline emerged is social pharmacology or sociopharmacology. This science arises from clinical pharmacology, and deals with different parameters, which are important in creating knowledge on marketed drugs. However, the scope of "social pharmacology" is not covered by the so-called "Phase IV" alone, but it is the science that handles the postmarketing knowledge of drugs. The social pharmacology studies the "life cycle" of any marketed pharmaceutical product in the social terrain, and evaluates the effects of the real environment under circumstances totally different in the drug development process. Therefore, there are far-reaching horizons, plural, and shared predictions among health professionals and other, for beneficial use of a drug, toward maximizing the benefits of therapy, while minimizing negative social consequences. PMID:24987168
Social Pharmacology: Expanding horizons
Maiti, Rituparna; Alloza, José Luis
2014-01-01
In the current modern and global society, social changes are in constant evolution due to scientific progress (technology, culture, customs, and hygiene) and produce the freedom in individuals to take decisions by themselves or with their doctors toward drug consumption. In the arena of marketed drug products which includes society, individual, administration, and pharmaceutical industry, the young discipline emerged is social pharmacology or sociopharmacology. This science arises from clinical pharmacology, and deals with different parameters, which are important in creating knowledge on marketed drugs. However, the scope of “social pharmacology” is not covered by the so-called “Phase IV” alone, but it is the science that handles the postmarketing knowledge of drugs. The social pharmacology studies the “life cycle” of any marketed pharmaceutical product in the social terrain, and evaluates the effects of the real environment under circumstances totally different in the drug development process. Therefore, there are far-reaching horizons, plural, and shared predictions among health professionals and other, for beneficial use of a drug, toward maximizing the benefits of therapy, while minimizing negative social consequences. PMID:24987168
Apparent horizons in binary black hole spacetimes
NASA Astrophysics Data System (ADS)
Shoemaker, Deirdre Marie
Over the last decade, advances in computing technology and numerical techniques have lead to the possible theoretical prediction of astrophysically relevant waveforms in numerical simulations. With the building of gravitational wave detectors such as the Laser Interferometric Gravitational-Wave Observatory, we stand at the epoch that will usher in the first experimental study of strong field general relativity. One candidate source for ground based detection of gravitational waveforms, the orbit and merger of two black holes, is of great interest to the relativity community. The binary black hole problem is the two-body problem in general relativity. It is a stringent dynamical test of the theory. The problem involves the evolution of the Einstein equation, a complex system of non-linear, dynamic, elliptic-hyperbolic equations intractable in closed form. Numerical relativists are now developing the technology to evolve the Einstein equation using numerical simulations. The generation of these numerical I codes is a ``theoretical laboratory'' designed to study strong field phenomena in general relativity. This dissertation reports the successful development and application of the first multiple apparent horizon tracker applied to the generic binary black hole problem. I have developed a method that combines a level set of surfaces with a curvature flow method. This method, which I call the level flow method, locates the surfaces of any apparent horizons in the spacetime. The surface location then is used to remove the singularities from the computational domain in the evolution code. I establish the following set of criteria desired in an apparent horizon tracker: (1)The robustness of the tracker due to its lack of dependence on small changes to the initial guess; (2)The generality of the tracker in its applicability to generic spacetimes including multiple back hole spacetimes; and (3)The efficiency of the tracker algorithm in CPU time. I demonstrate the apparent
Near-horizon Kerr magnetosphere
NASA Astrophysics Data System (ADS)
Gralla, Samuel E.; Lupsasca, Alexandru; Strominger, Andrew
2016-05-01
We exploit the near-horizon conformal symmetry of rapidly spinning black holes to determine universal properties of their magnetospheres. Analytic expressions are derived for the limiting form of the magnetosphere in the near-horizon region. The symmetry is shown to imply that the black hole Meissner effect holds for free Maxwell fields but is generically violated for force-free fields. We further show that in the extremal limit, near-horizon plasma particles are infinitely boosted relative to accretion flow. Active galactic nuclei powered by rapidly spinning black holes are therefore natural sites for high-energy particle collisions.
[Visual illusions and moving horizon].
Zhdan'ko, I M; Chulaevskiĭ, A O; Kovalenko, P A
2012-09-01
Results of psychological "additional investigation" of the crash of Boeing-737, "Aeroflot-Nord" on 14.09.2008 near Perm are presented. 37 pilots from the one of the leading airline companies sensed the attitude and rolling out the aircraft to the forward flight under the moving horizon with straight display of bank and tangage (view from the aircraft to the ground) in model conditions. 29 pilots (78.4%) made a mistake at determining the roll direction and tangage, they made a mistake at determining the roll direction 61 times (16.4%) and 44 times at determining the tangage direction, in other words they confused left and right bank and also nose-up and nose-down. Visual illusions of mobility of space and handling of ground (instead of aircraft) during the flight were revealed in pilots. These illusions may be the important cause of the following crashes. The necessity of "back" faultless display of bank in all aircrafts of civil aviation and development of computer complex for training of visual spatial orientation is proved. PMID:23156114
Quantum correlations through event horizons: Fermionic versus bosonic entanglement
Martin-Martinez, Eduardo; Leon, Juan
2010-03-15
We disclose the behavior of quantum and classical correlations among all the different spatial-temporal regions of a space-time with an event horizon, comparing fermionic with bosonic fields. We show the emergence of conservation laws for entanglement and classical correlations, pointing out the crucial role that statistics plays in the information exchange (and more specifically, the entanglement tradeoff) across horizons. The results obtained here could shed new light on the problem of information behavior in noninertial frames and in the presence of horizons, giving better insight into the black-hole information paradox.
Quantum correlations through event horizons: Fermionic versus bosonic entanglement
NASA Astrophysics Data System (ADS)
Martín-Martínez, Eduardo; León, Juan
2010-03-01
We disclose the behavior of quantum and classical correlations among all the different spatial-temporal regions of a space-time with an event horizon, comparing fermionic with bosonic fields. We show the emergence of conservation laws for entanglement and classical correlations, pointing out the crucial role that statistics plays in the information exchange (and more specifically, the entanglement tradeoff) across horizons. The results obtained here could shed new light on the problem of information behavior in noninertial frames and in the presence of horizons, giving better insight into the black-hole information paradox.
Area Theorem and Smoothness of Compact Cauchy Horizons
NASA Astrophysics Data System (ADS)
Minguzzi, E.
2015-10-01
We obtain an improved version of the area theorem for not necessarily differentiable horizons which, in conjunction with a recent result on the completeness of generators, allows us to prove that under the null energy condition every compactly generated Cauchy horizon is smooth and compact. We explore the consequences of this result for time machines, topology change, black holes and cosmic censorship. For instance, it is shown that compact Cauchy horizons cannot form in a non-empty spacetime which satisfies the stable dominant energy condition wherever there is some source content.
Status of the JPL Horizons Ephemeris System
NASA Astrophysics Data System (ADS)
Giorgini, Jon D.
2015-08-01
Since 1996, the NASA/Jet Propulsion Laboratory on-line Horizons system has provided open access to the latest JPL orbit solutions through customizable ephemeris generation and searches. Currently, high-precision ephemerides for more than 683,000 objects are available: all known solar system bodies, several dozen spacecraft, system barycenters, and some libration points.Since inception, Horizons has produced 150 million ephemeris products in response to 70.4 million connections by 800,000 unique IP addresses. Recent usage is typically 6000 unique users requesting 4,000,000 ephemeris products per month.Horizons is freely accessible without an account and may be used and automated through any of three interfaces: interactive telnet connection, web-browser form, or by sending e-mail command-files.Asteroid and comet ephemerides are numerically integrated on request using JPL's DASTCOM5 database of initial conditions which is kept current by a separate process; as new measurements and discoveries are reported by the Minor Planet Center, they are automatically processed into new JPL orbit solutions. Radar targets and other objects of high interest have their orbit solutions manually examined and updated into the database.For asteroids and comets, SPK files may be dynamically created using Horizons. This is effectively a recording of the integrator output. The binary files may then be efficiently interpolated by user software to exactly reproduce the trajectory without having to duplicate 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, and close-approach tables. More than one hundred quantities can be requested in various time-scales and coordinate systems. For asteroids and comets, statistical uncertainties can be mapped to output times to assess position and motion uncertainties.Horizons is consistent with the DE431 solar system solution
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.
Dynamical AdS strings across horizons
NASA Astrophysics Data System (ADS)
Ishii, Takaaki; Murata, Keiju
2016-03-01
We examine the nonlinear classical dynamics of a fundamental string in anti-de Sitter 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 Poincaré 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 vanish with a power law whose slope depends on the perturbations. The condition for this transition to occur is that energy injection exceeds the static energy between the quark-antiquark pair.
NEW HORIZONS IN SENSOR DEVELOPMENT
Intille, Stephen S.; Lester, Jonathan; Sallis, James F.; Duncan, Glen
2011-01-01
Background Accelerometery and other sensing technologies are important tools for physical activity measurement. Engineering advances have allowed developers to transform clunky, uncomfortable, and conspicuous monitors into relatively small, ergonomic, and convenient research tools. New devices can be used to collect data on overall physical activity and in some cases posture, physiological state, and location, for many days or weeks from subjects during their everyday lives. In this review article, we identify emerging trends in several types of monitoring technologies and gaps in the current state of knowledge. Best practices The only certainty about the future of activity sensing technologies is that researchers must anticipate and plan for change. We propose a set of best practices that may accelerate adoption of new devices and increase the likelihood that data being collected and used today will be compatible with new datasets and methods likely to appear on the horizon. Future directions We describe several technology-driven trends, ranging from continued miniaturization of devices that provide gross summary information about activity levels and energy expenditure, to new devices that provide highly detailed information about the specific type, amount, and location of physical activity. Some devices will take advantage of consumer technologies, such as mobile phones, to detect and respond to physical activity in real time, creating new opportunities in measurement, remote compliance monitoring, data-driven discovery, and intervention. PMID:22157771
NASA Astrophysics Data System (ADS)
Botor, Dariusz; Anczkiewicz, Aneta A.
2015-10-01
Apatite fission track (AFT) central ages from Carboniferous (Stephanian) tonsteins of the Sabero Coalfield, NW Spain, range from 140.8 ± 7.5 to 65.8 ± 8.1 Ma (Cretaceous), with mean c-axis projected track length values ranging from 12.5 to 13.4 μm. Mean random vitrinite reflectance ( R r) of these samples ranges from 0.91 to 1.20 %, which can be translated into maximum palaeotemperatures of ca. 130 to 180 °C. All analysed samples experienced substantial post-depositional annealing. The considerably younger AFT ages compared to the depositional ages of the samples and R r data indicate the certainty of the occurrence of at least one heating event after the deposition of strata. The unimodal track length distributions, the relatively short mean track length, and the rather low standard deviation (SD) (1.0-1.6 μm) indicate a relatively simple thermal history that could be related to the post-Late Variscan heating event followed by prolonged residence in the apatite partial annealing zone (APAZ). Geological data combined with thermal models of AFT data indicate that Stephanian strata reached the maximum palaeotemperatures in the Permian period, which was therefore the major time of the coalification processes. The Permian magmatic activity was responsible for a high heat flow, which, with the added effect of sedimentary burial, could account for the resetting of the AFT system. It appears that the fault-related hydrothermal activity could have redistributed heat in areas of significant subsidence. Cooling occurred in the Triassic-Cretaceous times after a high heat flow Permian regime. A post-Permian maturation of the Stephanian organic matter is not very likely, since there is no evidence of a high Mesozoic burial that was sufficient to cause a significant increase in the palaeotemperatures. Finally, exhumation and associated erosion rates may possibly have been faster in the Tertiary, causing the present exposure of the studied rocks.
Exact event horizon of a black hole merger
NASA Astrophysics Data System (ADS)
Emparan, Roberto; Martínez, Marina
2016-08-01
We argue that the event horizon of a binary black hole merger, in the extreme-mass-ratio limit where one of the black holes is much smaller than the other, can be described in an exact analytic way. This is done by tracing in the Schwarzschild geometry a congruence of null geodesics that approaches a null plane at infinity. Its form can be given explicitly in terms of elliptic functions, and we use it to analyze and illustrate the time-evolution of the horizon along the merger. We identify features such as the line of caustics at which light rays enter the horizon, and the critical point at which the horizons touch. We also compute several quantities that characterize these aspects of the merger.
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 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.
Air fluorescence detection of large air showers below the horizon
NASA Technical Reports Server (NTRS)
Halverson, P.; Bowen, T.
1985-01-01
In the interest of exploring the cosmic ray spectrum at energies greater than 10 to the 18th power eV, where flux rates at the Earth's surface drop below 100 yr(-1) km(-2) sr(-1), cosmic ray physicists have been forced to construct ever larger detectors in order to collect useful amounts of data in reasonable lengths of time. At present, the ultimate example of this trend is the Fly's Eye system in Utah, which uses the atmosphere around an array of skyward-looking photomultiplier tubes. The air acts as a scintillator to give detecting areas as large as 5000 square kilometers sr (for highest energy events). This experiment has revealed structure (and a possible cutoff) in the ultra-high energy region above 10 o the 19th power eV. The success of the Fly's Eye experiment provides impetus for continuing the development of larger detectors to make accessible even higher energies. However, due to the rapidly falling flux, a tenfold increase in observable energy would call for a hundredfold increase in the detecting area. But, the cost of expanding the Fly's Eye detecting area will approximately scale linearly with area. It is for these reasons that the authors have proposed a new approach to using the atmosphere as a scintillator; one which will require fewer photomultipliers, less hardware (thus being less extensive), yet will provide position and shower size information.
Brian Cox
2010-09-01
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.
Common Ground: Expanding Our Horizons.
ERIC Educational Resources Information Center
McDevitt, Michele J.
In "Common Ground: Dialogue, Understanding, and the Teaching of Composition," Kurt Spellmeyer seeks to familiarize students and teachers with the linguistic and cultural no-man's-land separating them. Reinstating the value of two writing conventions often used by traditional students--expressive and commonplaces--can help expand on the horizons of…
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 Chan); "Critical…
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.
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.
Generic isolated horizons and their applications
Ashtekar; Beetle; Dreyer; Fairhurst; Krishnan; Lewandowski; Wisniewski
2000-10-23
The notion of isolated horizons is extended to allow for distortion and rotation. Space-times containing a black hole, itself in equilibrium but possibly surrounded by radiation, satisfy these conditions. The framework has three types of applications: (i) it provides new tools to extract physics from strong field geometry; (ii) it leads to a generalization of the zeroth and first laws of black hole mechanics and sheds new light on the "origin" of the first law; and (iii) it serves as a point of departure for black hole entropy calculations in nonperturbative quantum gravity. PMID:11030951
Art, the Urban Skyscraper, and Horizon Astronomy
NASA Astrophysics Data System (ADS)
Mooney, J. D.
2016-01-01
This presentation delineates the historiography and the iconography of my urban public sculptures which use skyscrapers as today's standing stones, markers for horizon astronomy. From 1977 to the present time, my work has engaged the public to “look up and see.” Through ephemeral works in the sky and over the water to large-scale rooftop sculptures in Los Angeles, Chicago, Atlanta, and Europe, viewers are oriented to the Milky Way, the summer triangle, and other celestial phenomena. This new urban scale art, transformative in context and gesture, has become part of the new cultural landscape.
NASA Astrophysics Data System (ADS)
Vanzo, L.
2011-07-01
The tunneling method for stationary black holes in the Hamilton-Jacobi variant is reconsidered in the light of some critiques that have been moved against. It is shown that once the tunneling trajectories have been correctly identified the method is free from internal inconsistencies, it is manifestly covariant, it allows for the extension to spinning particles and it can even be used without solving the Hamilton-Jacobi equation. These conclusions borrow support on a simple analytic continuation of the classical action of a pointlike particle, made possible by the unique assumption that it should be analytic in the complexified Schwarzschild or Kerr-Newman space-time. A more general version of the Parikh-Wilczek method will also be proposed along these lines.
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.
Geometric properties of static Einstein-Maxwell dilaton horizons with a Liouville potential
Abdolrahimi, Shohreh; Shoom, Andrey A.
2011-05-15
We study nondegenerate and degenerate (extremal) Killing horizons of arbitrary geometry and topology within the Einstein-Maxwell-dilaton model with a Liouville potential (the EMdL model) in d-dimensional (d{>=}4) static space-times. Using Israel's description of a static space-time, we construct the EMdL equations and the space-time curvature invariants: the Ricci scalar, the square of the Ricci tensor, and the Kretschmann scalar. Assuming that space-time metric functions and the model fields are real analytic functions in the vicinity of a space-time horizon, we study the behavior of the space-time metric and the fields near the horizon and derive relations between the space-time curvature invariants calculated on the horizon and geometric invariants of the horizon surface. The derived relations generalize similar relations known for horizons of static four- and five-dimensional vacuum and four-dimensional electrovacuum space-times. Our analysis shows that all the extremal horizon surfaces are Einstein spaces. We present the necessary conditions for the existence of static extremal horizons within the EMdL model.
Fermion tunneling from dynamical horizons
NASA Astrophysics Data System (ADS)
Di Criscienzo, R.; Vanzo, L.
2008-06-01
The instability against emission of fermionic particles by the trapping horizon of an evolving black hole is analyzed and confirmed using the Hamilton-Jacobi tunneling method. This method automatically selects one special expression for the surface gravity of a changing horizon. The results also apply to point masses embedded in an expanding universe. As a bonus of the tunneling method, we gain the insight that the surface gravity still defines a temperature parameter as long as the evolution is sufficiently slow that the black-hole pass through a sequence of quasi-equilibrium states, and that black holes should be semi-classically unstable even in a hypothetical world without bosonic fields.
Penrose inequality and apparent horizons
Ben-Dov, Ishai
2004-12-15
A spherically symmetric spacetime is presented with an initial data set that is asymptotically flat, satisfies the dominant energy condition, and such that on this initial data M<{radical}(A/16{pi}), where M is the total mass and A is the area of the apparent horizon. This provides a counterexample to a commonly stated version of the Penrose inequality, though it does not contradict the true Penrose inequality.
New Horizons Tracks an Asteroid
NASA Technical Reports Server (NTRS)
2007-01-01
The two 'spots' 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 (MVIC) component of the New Horizons Ralph imager. In the bottom image, taken when the asteroid was about 3.36 million kilometers (2.1 million miles) away from the spacecraft, 2002 JF56 appears like a dim star. At top, taken at a distance of about 1.34 million kilometers (833,000 miles), the object is more than a factor of six brighter. The best current, estimated diameter of the asteroid is approximately 2.5 kilometers.
The asteroid observation was a chance for the New Horizons team to test the spacecraft's ability to track a rapidly moving object. On June 13 New Horizons came to within about 102,000 kilometers of the small asteroid, when the spacecraft was nearly 368 million kilometers (228 million miles) from the Sun and about 273 million kilometers (170 million miles) from Earth.
A receding horizon approach for dynamic UAV mission management
NASA Astrophysics Data System (ADS)
Cassandras, Christos G.; Li, Wei
2003-09-01
We consider a setting where multiple UAVs form a team cooperating to visit multiple targets to collect rewards associated with them. The team objective is to maximize the total reward accumulated over a given time interval. Complicating factors include uncertainties regarding the locations of targets and the effectiveness of collecting rewards, differences among vehicle capabilities, and the fact that rewards are time-varying. We describe a Receding Horizon (RH) control scheme which dynamically assigns vehicles to targets and simultaneously determines associated trajectories. This scheme is based on solving a sequence of optimization problems over a planning horizon and executing them over a shorter action horizon. We also describe a simulated battlespace environment designed to test UAV team missions and to illustrate how the RH scheme can achieve optimal performance with high probability.
Beyond the veil: Inner horizon instability and holography
Balasubramanian, Vijay; Levi, Thomas S.
2004-11-15
We show that scalar perturbations of the eternal, rotating Banados-Teitelboim-Zanelli (BTZ) black hole should lead to an instability of the inner (Cauchy) horizon, preserving strong cosmic censorship. Because of backscattering from the geometry, plane-wave modes have a divergent stress tensor at the event horizon, but suitable wave packets avoid this difficulty, and are dominated at late times by quasinormal behavior. The wave packets have cuts in the complexified coordinate plane that are controlled by requirements of continuity, single-valuedness, and positive energy. Due to a focusing effect, regular wave packets nevertheless have a divergent stress energy at the inner horizon, signaling an instability. We propose that this instability, which is localized behind the event horizon, is detected holographically as a breakdown in the semiclassical computation of dual conformal field theory (CFT) expectation values in which the analytic behavior of wave packets in the complexified coordinate plane plays an integral role. In the dual field theory, this is interpreted as an encoding of physics behind the horizon in the entanglement between otherwise independent CFTs.
Topological deformation of isolated horizons
Liko, Tomas
2008-03-15
We show that the Gauss-Bonnet term can have physical effects in four dimensions. Specifically, the entropy of a black hole acquires a correction term that is proportional to the Euler characteristic of the cross sections of the horizon. While this term is constant for a single black hole, it will be a nontrivial function for a system with dynamical topologies such as black-hole mergers: it is shown that for certain values of the Gauss-Bonnet parameter, the second law of black-hole mechanics can be violated.
Variable horizon in a peridynamic medium
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 forces 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.
Variable horizon in a peridynamic medium.
Silling, Stewart Andrew; Littlewood, David John; Seleson, Pablo
2014-10-01
A notion of material homogeneity is proposed for peridynamic bodies with vari- able 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 un- changed. Using this scaling relation, if the horizon depends on position, artifacts called ghost forces may arise in a body under homogeneous deformation. These artifacts de- pend on the second derivative of horizon and can be reduced by use of a modified equilibrium equation using a new quantity called the partial stress . Bodies with piece- wise constant horizon can be modeled without ghost forces by using a technique called a splice between the regions. As a limiting case of zero horizon, both 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.
Variable horizon in a peridynamic medium
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
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.
A MIP Model for Rolling Horizon Surgery Scheduling.
Luo, Li; Luo, Yong; You, Yang; Cheng, Yuanjun; Shi, Yingkang; Gong, Renrong
2016-05-01
Most surgery scheduling is done 1 day in advance. Caused by lack of overall planning, this scheduling scheme often results in unbalanced occupancy time of the operating rooms. So we put forward a rolling horizon mixed integer programming model for the scheduling. Rolling horizon scheduling refers to a scheduling scheme in which cyclic surgical requests are taken into account. Surgical requests are updated daily. The completed surgeries are eliminated, and new surgeries are added to the scheduling list. Considering day-to-day demand for surgery, we develop a non-rolling scheduling model (NRSM) and a rolling horizon scheduling model (RSM). By comparing the two, we find that the quality of surgery scheduling is significantly influenced by the variation in demand from day to day. A rolling horizon scheduling will enable a more flexible planning of the pool of surgeries that have not been scheduled into this main blocks, and hence minimize the idle time of operating rooms. The strategy of the RSM helps balance the occupancy time among operating rooms. Using surgical data from five departments of the West China Hospital (WCH), we generate surgical demands randomly to compare the NRSM and the RSM. The results show the operating rooms' average utilization rate using RSM is significantly higher than when applying NRSM. PMID:27071394
Spectroscopy of a weakly isolated horizon
NASA Astrophysics Data System (ADS)
Chen, Ge-Rui; Huang, Yong-Chang
2016-06-01
The spectroscopy of a weakly isolated horizon has been investigated. We obtain an equally spaced entropy spectrum with its quantum equal to the one given by Bekenstein (Phys Rev D 7:2333, 1973). We demonstrate that the quantization of entropy and area is a generic property of horizons which exists in a wide class of spacetimes admitting weakly isolated horizons. Our method based on the tunneling method also indicates that the entropy quantum of black hole horizons is closely related to Hawking temperature.
Priority Questions and Horizon Scanning for Conservation: A Comparative Study
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
Priority Questions and Horizon Scanning for Conservation: A Comparative Study.
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
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…
Reconceptualizing Knowledge at the Mathematical Horizon
ERIC Educational Resources Information Center
Zazkis, Rina; Mamolo, Ami
2011-01-01
This article extends the notion of "knowledge at the mathematical horizon" or "horizon knowledge" introduced by Ball and colleagues as a part of teachers' subject matter knowledge. Our focus is on teachers' mathematical knowledge beyond the school curriculum, that is, on mathematics learnt during undergraduate college or university studies. We…
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…
Expanding your horizons in science and mathematics
NASA Technical Reports Server (NTRS)
Palmer, Cynthia E. A.
1995-01-01
The purpose of the 'Expanding Your Horizons in Science and Mathematics' program is to interest young women in grades six through twelve in a variety of careers where mathematics and science are important. Progress in encouraging young women to take courses in mathematics, science, and technological subjects is discussed. Also included are adult, student, and organizational information packets used for 'Expanding Your Horizons' conferences.
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…
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…
High-frequency over-the-horizon radar and ionospheric backscatter studies in China
NASA Astrophysics Data System (ADS)
Li, Le-Wei
1998-09-01
China is one of the countries that employs high-frequency over-the-horizon radars for both military and civil applications. The first Chinese high-frequency over-the horizon backscatter radar was developed in the 1970s. This paper briefly introduces the first Chinese over-the-horizon backscatter radar system and reviews ionospheric backscatter and propagation studies in China. The paper discusses the motivation for establishing over-the-horizon radar systems in China, the experimental system, target recognition and detection,and estimation of over-the-horizon radar availability. Observations of aircraft, large-scale traveling ionospheric disturbances, and the effects of a remote nuclear explosion are also presented. Finally, the real-time Chinese ionosonde network and frequency predictions using backscatter ionograms are discussed.
Estimation of the Horizon in Photographed Outdoor Scenes by Human and Machine
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
Spherically Symmetric Trapping Horizons, the Misner-Sharp Mass and Black Hole Evaporation
NASA Astrophysics Data System (ADS)
Nielsen, Alex B.; Yeom, Dong-Han
We discuss some of the issues relating to information loss and black hole thermodynamics in the light of recent work on local black hole horizons. Understood in terms of pure states evolving into mixed states, the possibility of information loss in black holes is closely related to the global causal structure of space-time, as is the existence of event horizons. However, black holes need not be defined by event horizons, and in fact we argue that in order to have a fully unitary evolution for black holes, they should be defined in terms of something else, such as a trapping horizon. The Misner-Sharp mass in spherical symmetry shows very simply how trapping horizons can give rise to black hole thermodynamics, Hawking radiation and singularities. We show how the Misner-Sharp mass can also be used to give insights into the process of collapse and evaporation of locally defined black holes.
Gravitational black hole hair from event horizon supertranslations
NASA Astrophysics Data System (ADS)
Averin, Artem; Dvali, Gia; Gomez, Cesar; Lüst, Dieter
2016-06-01
We discuss BMS supertranslations both at null-infinity BMS- and on the horizon {BMS}^{mathscr{H}} for the case of the Schwarzschild black hole. We show that both kinds of supertranslations lead to infinetly many gapless physical excitations. On this basis we construct a quotient algebra mathcal{A}equiv {BMS}^{mathscr{H}}/{BMS}- using suited superpositions of both kinds of transformations which cannot be compensated by an ordinary BMS-supertranslation and therefore are intrinsically due to the presence of an event horizon. We show that transformations in mathcal{A} are physical and generate gapless excitations on the horizon that can account for the gravitational hair as well as for the black hole entropy. We identify the physics of these modes as associated with Bogolioubov-Goldstone modes due to quantum criticality. Classically the number of these gapless modes is infinite. However, we show that due to quantum criticality the actual amount of information-carriers becomes finite and consistent with Bekenstein entropy. Although we only consider the case of Schwarzschild geometry, the arguments are extendable to arbitrary space-times containing event horizons.
New Horizons' Extreme Close-Up of Pluto’s Surface (no audio)
This is the most detailed view of Pluto’s terrain you’ll see for a very long time. This mosaic strip – extending across the hemisphere that faced the New Horizons spacecraft as it flew past Pluto o...
Quasilocal approach to general universal horizons
NASA Astrophysics Data System (ADS)
Maciel, Alan
2016-05-01
Theories of gravity with a preferred foliation usually display arbitrarily fast signal propagation, changing the black hole definition. A new inescapable barrier, the universal horizon, has been defined and many static and spherically symmetric examples have been studied in the literature. Here, we translate the usual definition of the universal horizon in terms of an optical scalar built with the preferred flow defined by the preferred spacetime foliation. The new expression has the advantages of being of quasilocal nature and independent of specific spacetime symmetries in order to be well defined. Therefore, we propose it as a definition for general quasilocal universal horizons. Using the new formalism, we show that there is no universal analog of cosmological horizons for Friedmann-Lemaître-Robertson-Walker models for any scale factor function, and we also state that quasilocal universal horizons are restricted to trapped regions of the spacetime. Using the evolution equation, we analyze the formation of universal horizons under a truncated Hořava-Lifshitz theory, in spherical symmetry, showing the existence of regions in parameter space where the universal horizon formation cannot be smooth from the center, under some physically reasonable assumptions. We conclude with our view on the next steps for the understanding of black holes in nonrelativistic gravity theories.
NASA Astrophysics Data System (ADS)
Dadras, Pouria; Firouzjaee, J. T.; Mansouri, Reza
2012-11-01
We propose a special solution of Einstein equations in the general Vaidya form representing a dynamical black hole having horizon cross-sections with toroidal topology. The concrete model enables us to study for the first time dynamical horizons with toroidal topology, its area law, and the question of matter flux inside the horizon, without using a cut-and-paste technology to construct the solution.
Production and decay of evolving horizons
NASA Astrophysics Data System (ADS)
Nielsen, Alex B.; Visser, Matt
2006-07-01
We consider a simple physical model for an evolving horizon that is strongly interacting with its environment, exchanging arbitrarily large quantities of matter with its environment in the form of both infalling material and outgoing Hawking radiation. We permit fluxes of both lightlike and timelike particles to cross the horizon, and ask how the horizon grows and shrinks in response to such flows. We place a premium on providing a clear and straightforward exposition with simple formulae. To be able to handle such a highly dynamical situation in a simple manner we make one significant physical restriction—that of spherical symmetry—and two technical mathematical restrictions: (1) we choose to slice the spacetime in such a way that the spacetime foliations (and hence the horizons) are always spherically symmetric. (2) Furthermore, we adopt Painlevé Gullstrand coordinates (which are well suited to the problem because they are nonsingular at the horizon) in order to simplify the relevant calculations. Of course physics results are ultimately independent of the choice of coordinates, but this particular coordinate system yields a clean physical interpretation of the relevant physics. We find particularly simple forms for surface gravity, and for the first and second law of black hole thermodynamics, in this general evolving horizon situation. Furthermore, we relate our results to Hawking's apparent horizon, Ashtekar and co-worker's isolated and dynamical horizons, and Hayward's trapping horizon. The evolving black hole model discussed here will be of interest, both from an astrophysical viewpoint in terms of discussing growing black holes and from a purely theoretical viewpoint in discussing black hole evaporation via Hawking radiation.
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
On the thermodynamics of the cosmological apparent horizon
NASA Astrophysics Data System (ADS)
Pollock, M. D.
2015-11-01
It has been shown by Cai et al. that the apparent horizon of radius r0 in the cosmological Friedmann space-time emits radiation at the temperature T0 = 1/2π r0. Here, we derive this result from the Wheeler-DeWitt equation for the wave function of the Universe Ψ, starting from a classical gravitational Lagrangian L that contains a quadratic higher-derivative term R2 , the scalar component of which is non-tachyonic, by application of the horizon hypothesis and definition of the physical three-space on the time-slice dx0 = 0. We also extend our previous analysis of the Wheeler-DeWitt equation for the wave function Φ of the apparent horizon of the de Sitter space-time to include the case of a more general energy-momentum source, that generates an arbitrary Friedmann space-time, confirming the expression for T0 after application of the ADM formalism.
Quantum Phase Transitions and Event Horizons:. Condensed Matter Analogies
NASA Astrophysics Data System (ADS)
Chapline, George
2006-07-01
Although it has been generally believed that classical general relativity is always correct for macroscopic length scales, certain predictions such as event horizons and closed time-like curves are inconsistent with ordinary quantum mechanics. It has recently been pointed out that the event horizon problem can be resolved if space-time undergoes a quantum phase transition as one approaches the surface where general relativity predicts that the redshift becomes infinite. Indeed a thought experiment involving a superfluid with a critical point makes such a suggestion appear plausible. Furthermore the behavior of space-time near an event horizon may resemble quantum phase transitions that have been observed in the laboratory. For example, the phenomenology of meta-magnetic quantum critical points in heavy fermion materials resembles the behavior expected, both in terms of time standing still and the behavior of quantum correlation functions. Martensitic transformations accompanied by non-adiabatic changes in the electronic wave function are also interesting in this connection.
Horizon Entropy from Quantum Gravity Condensates
NASA Astrophysics Data System (ADS)
Oriti, Daniele; Pranzetti, Daniele; Sindoni, Lorenzo
2016-05-01
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.
Horizon Entropy from Quantum Gravity Condensates.
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. PMID:27284642
Information Horizons in Complex Networks
NASA Astrophysics Data System (ADS)
Sneppen, Kim
2005-03-01
We investigate how the structure constrain specific communication in social-, man-made and biological networks. We find that human networks of governance and collaboration are predictable on teat-a-teat level, reflecting well defined pathways, but globally inefficient (1). In contrast, the Internet tends to have better overall communication abilities, more alternative pathways, and is therefore more robust. Between these extremes are the molecular network of living organisms. Further, for most real world networks we find that communication ability is favored by topology on small distances, but disfavored at larger distances (2,3,4). We discuss the topological implications in terms of modularity and the positioning of hubs in the networks (5,6). Finally we introduce some simple models which demonstarte how communication may shape the structure of in particular man made networks (7,8). 1) K. Sneppen, A. Trusina, M. Rosvall (2004). Hide and seek on complex networks [cond-mat/0407055] 2) M. Rosvall, A. Trusina, P. Minnhagen and K. Sneppen (2004). Networks and Cities: An Information Perspective [cond-mat/0407054]. In PRL. 3) A. Trusina, M. Rosvall, K. Sneppen (2004). Information Horizons in Networks. [cond-mat/0412064] 4) M. Rosvall, P. Minnhagen, K. Sneppen (2004). Navigating Networks with Limited Information. [cond-mat/0412051] 5) S. Maslov and K. Sneppen (2002). Specificity and stability in topology of protein networks Science 296, 910-913 [cond-mat/0205380]. 6) A. Trusina, S. Maslov, P. Minnhagen, K. Sneppen Hierarchy Measures in Complex Networks. Phys. Rev. Lett. 92, 178702 [cond-mat/0308339]. 7) M. Rosvall and K. Sneppen (2003). Modeling Dynamics of Information Networks. Phys. Rev. Lett. 91, 178701 [cond-mat/0308399]. 8) B-J. Kim, A. Trusina, P. Minnhagen, K. Sneppen (2003). Self Organized Scale-Free Networks from Merging and Regeneration. nlin.AO/0403006. In European Journal of Physics.
Cerqueira, B; Vega, F A; Serra, C; Silva, L F O; Andrade, M L
2011-11-15
Relatively new techniques can help in determining the occurrence of mineral species and the distribution of contaminants on soil surfaces such as natural minerals and organic matter. The Bt horizon from an Endoleptic Luvisol was chosen because of its well-known sorption capability. The samples were contaminated with Cu(2+) and/or Pb(2+) and both sorption and desorption experiments were performed. The preferential distribution of the contaminant species ((63)Cu and (208)Pb) to the main soil components and their associations were studied together with the effectiveness of the surface sorption and desorption processes. The results obtained were compared with non-contaminated samples as well as with previous results obtained by different analytical techniques and advanced statistical analysis. Pb(2+) competes favorably for the sorption sites in this soil, mainly in oxides and the clay fraction. Cu(2+) and Pb(2+) were mainly associated with hematite, gibbsite, vermiculite and chlorite. This study will serve as a basis for further scientific research on the soil retention of heavy metals. New techniques such as spectroscopic imaging and transmission electron microscopy make it possible to check which soil components retain heavy metals, thereby contributing to propose effective measures for the remediation of contaminated soil. PMID:21920666
If you stood on Pluto at noon and looked around, the landscape would be illuminated about as brightly as on Earth soon after sunset. The team for NASA's New Horizons mission dubbed this "Pluto Time...
Possible New Horizons Fundamental Contribution to Cosmology
NASA Astrophysics Data System (ADS)
Conn Henry, Richard; Murthy, Jayant
2016-01-01
The New Horizons (NH) spacecraft (S. Alan Stern, PI) is now past Pluto, and in our poster we explore the possibility of making observations, using the NH P-Alice ultraviolet spectrometer, of the cosmic diffuse ultraviolet background radiation, particularily at high northern and southern Galactic latitudes. In the paper, "The Mystery of the Cosmic Diffuse Ultraviolet Background Radiation," by Richard Conn Henry, Jayant Murthy, James Overduin, Joshua Tyler, ApJ, 798:14 (25pp), 2015 January 1, we demonstrated the existence of a second component of the diffuse far ultraviolet background radiation beyond that provided by dust-scattered starlight. The critical question is, does that second component (of unknown origin) extend shortward of the Lyman limit of 912 Å? If it does, then it seems likely that we have discovered the source of the reionization of the Universe that occurred some time after recombination. As things stand at the moment, there is no known source that has been demonstrated to be capable of performing the reionization: reionization that clearly did occur. Our current understanding of P-Alice suggests that it may well be capable of demonstrating the presence (or absence) of such ionizing cosmic diffuse radiation. At low Galactic latitudes, all such radiation would be totally erased by the presence, in large quantities, of interstellar neutral hydrogen; this will allow us to test the reality of any such flux that we may discover at higher Galactic latitudes.
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.
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.
NASA Astrophysics Data System (ADS)
Abramowicz, Marek A.
Three advanced instruments planned for a near future ( LOFT, GRAVITY, THE EVENT HORIZON TELESCOPE) provide unprecedented angular and time resolutions, which allow to probe regions in the immediate vicinity of black holes. We may soon be able to search for the signatures of the super-strong gravity that is characteristic to black holes: the event horizon, the ergosphere, the innermost stable circular orbit (ISCO), and the photon circle. This review discusses a few fundamental problems concerning these theoretical concepts.
The New Horizons Mission to Pluto and the Kuiper Belt
NASA Astrophysics Data System (ADS)
Weaver, H. A.; Stern, S. A.; New Horizons Science; Engineering Team
New Horizons, which initiates the NASA New Frontiers program of mid-sized missions, will provide the first scientific reconnaissance of the Pluto-Charon system and is scheduled for launch in January 2006. An encounter with Jupiter at a flyby distance of ˜32-45 RJ about 13 months after launch provides a gravity boost for the spacecraft's journey to Pluto and practice for the Pluto encounter, in addition to providing an opportunity to perform a valuable set of scientific measurements within the jovian system. New Horizons carries a sophisticated suite of instruments to perform ultraviolet and infrared spectroscopy, panchromatic and color optical imaging, and charged particle and dust measurements, all within a spacecraft having a total mass of ˜465 kg and total power output of ˜210 W at the time of Pluto encounter in July 2015. The primary scientific objectives of the New Horizons are to characterize the global geology and morphology of Pluto and Charon, map the surface composition of Pluto and Charon, and characterize the neutral atmosphere and its escape rate, but many other important scientific objectives will be addressed as well. New Horizons has the capability to image Pluto with a resolution exceeding that provided by the Hubble Space Telescope for at least 90 days prior to closest approach at a distance of ˜10,000 km from the surface, at which time a resolution of ˜100 m will be achieved for selected regions near the terminator. After encounter, the spacecraft will pass through the shadows of both Pluto and Charon, which enables radio and ultraviolet occultation measurements of their atmospheres. If an extended mission phase is approved, the spacecraft will be re-targeted to encounter one or more Kuiper belt objects (KBOs), roughly 3 years after the Pluto encounter at a heliocentric distance of ˜42 AU. The scientific objectives for the KBO encounters are similar to those for the Pluto encounter.
Aluminum solubility control in different horizons of a podzol
Zysset, M.; Blaser, P.; Luster, J.; Gehring, A.U.
1999-10-01
In the last two decades, the anthropogenically induced acceleration of forest soil acidification has been a topic of environmental concern. Aluminum extractability and solubility were investigated in detail in six horizons of a Typic Haplohumod (FAO:Haplic Podzol) from southern Switzerland. Pyrophosphate and oxalate extractions as well as successive acid leaching indicated that in the Ah, (AE), and Bh horizons reactive Al is mainly bound to soil organic matter, whereas in the Bs, BC1, and BC2 horizons it is of inorganic nature. In the latter three horizons, infrared (IR) spectroscopy and transmission electron microscopy (TEM) revealed the presence of imogolite. Batch equilibrium experiments at 20 C in the pH range of approximately 3.5 to 5.5 showed that the podzol profile can be divided into two parts of different Al solubility control. In the Ah and (AE) horizons, Al solubility was found to be controlled by complexation reactions to soil organic matter. Kinetic studies with samples of the Bh, Bs, BC1, and BC2 horizons showed that ion activity products with respect to both Al(OH){sub 3} and imogolite, (HO){sub 3}Al{sub 2}O{sub 3}SiOH, reached a constant value after reaction times of 16 d. For pH {gt}4.1, the compilation of all data revealed pAl + 0.5 pSi = 3.05 pH {minus} 7.04 (r{sup 2} = 0.99) and pAl = 2.87 pH {minus} 8.07 (r{sup 2} = 0.99). These data could be shown to be consistent with either Al solubility control by imogolite-type material (ITM) with a log *K{sub s}{sup 0} = 6.53 {+-} 0.09, which dissolves incongruently, or a simultaneous equilibrium with ITM and hydroxy-Al interlayers of clay minerals. For pH {lt} 4.1, data indicated solubility control by a 1:1 aluminosilicate, e.g., poorly crystalline kaolinite.
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.
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.
The Event Horizon Telescope: New Developments and Results
NASA Astrophysics Data System (ADS)
Johnson, Michael D.; Doeleman, Sheperd S.; Event Horizon Telescope Collaboration
2015-08-01
A convergence of high-bandwidth radio instrumentation and global submillimeter facilities is enabling assembly of the Event Horizon Telescope (EHT): a short-wavelength Very-Long-Baseline Interferometry array capable of observing the nearest supermassive black holes with Schwarzschild-radius resolution. Initial observations with the EHT have revealed event-horizon-scale structure in Sgr A*, the 4 million solar mass black hole at the Galactic center, and in the much more luminous and massive black hole at the center of the giant elliptical galaxy M87. The past year has witnessed rapid expansion of the array, including first light and successful interferometric fringes for new receivers at the Large Millimeter Telescope in Mexico and the South Pole Telescope, as well as fringes to the ALMA phased array. Concurrent instrumental developments also allow 2 GHz observing bandwidth with dual polarization in the 2015 observing campaign. Together, these advances will yield an unprecedented combination of sensitivity and resolution, with excellent prospects for imaging strong general relativistic signatures, detecting horizon-scale magnetic field structures through full polarization observations, and time-resolving dynamical activity near a black hole. I will briefly review the recent developments and technical timeline for completing the EHT and will present new results from our 2013 observing campaign.
The Orbits and Masses of Pluto's Satellites after New Horizons
NASA Astrophysics Data System (ADS)
Jacobson, Robert A.; Brozovic, Marina; Buie, Marc; Porter, Simon; Showalter, Mark; Spencer, John; Stern, S. Alan; Weaver, Harold; Young, Leslie; Ennico, Kimberly; Olkin, Cathy
2015-11-01
Brozović et al. (2015 Icarus 246, 317) reported on Pluto's mass and the masses and numerically integrated orbits of Pluto's satellites, Charon, Nix, Hydra, Kerberos, and Styx. These were determined via a fit to an extensive set of astrometric, mutual event, and stellar occultation observations over the time interval April 1965 to July 2012. The data set contained the Hubble Space Telescope (HST) observations of Charon relative to Pluto that were corrected for the Pluto center-of-figure center-of-light offset due to the Pluto albedo variations (Buie et al. 2012 AJ 144, 15). Also included were all of the available HST observations of Nix, Hydra, Kerberos, and Styx. For the New Horizons encounter with the Pluto system, the initial satellite ephemerides (PLU043) and the initial planet and satellite masses were taken from the Brozović et al. analysis. During the New Horizons approach, the ephemerides and masses were periodically updated along with the spacecraft trajectory by the New Horizons navigation team using imaging of the planet and satellites against the stellar background. In this work, we report on our post-flyby analysis of the masses and satellite orbits derived from a combination of the original PLU043 data set, the New Horizions imaging data, and HST observations acquired after 2012.
On horizons and wormholes in k-essence theories
NASA Astrophysics Data System (ADS)
Bronnikov, K. A.; Fabris, J. C.; Rodrigues, Denis C.
2016-01-01
We study the properties of possible static, spherically symmetric configurations in k-essence theories with the Lagrangian functions of the form $F(X)$, $X \\equiv \\phi_{,\\alpha} \\phi^{,\\alpha}$. A no-go theorem has been proved, claiming that a possible black-hole-like Killing horizon of finite radius cannot exist if the function $F(X)$ is required to have a finite derivative $dF/dX$. Two exact solutions are obtained for special cases of k-essence: one for $F(X) =F_0 X^{1/3}$, another for $F(X) = F_0 |X|^{1/2} - 2 \\Lambda$, where $F_0$ and $\\Lambda$ are constants. Both solutions contain horizons, are not asymptotically flat, and provide illustrations for the obtained no-go theorem. The first solution may be interpreted as describing a black hole in an asymptotically singular space-time, while in the second solution two horizons of infinite area are connected by a wormhole.
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.
Holography of 3D flat cosmological horizons.
Bagchi, Arjun; Detournay, Stéphane; Fareghbal, Reza; Simón, Joan
2013-04-01
We provide a first derivation of the Bekenstein-Hawking entropy of 3D flat cosmological horizons in terms of the counting of states in a dual field theory. These horizons appear in the flat limit of nonextremal rotating Banados-Teitleboim-Zanelli black holes and are remnants of the inner horizons. They also satisfy the first law of thermodynamics. We study flat holography as a limit of AdS(3)/CFT(2) to semiclassically compute the density of states in the dual theory, which is given by a contraction of a 2D conformal field theory, exactly reproducing the bulk entropy in the limit of large charges. We comment on how the dual theory reproduces the bulk first law and how cosmological bulk excitations are matched with boundary quantum numbers. PMID:25166977
East Rim of Endeavour Crater on Horizon
NASA Technical Reports Server (NTRS)
2009-01-01
[figure removed for brevity, see original site]
A high point on the distant eastern rim of Endeavour Crater is visible on the horizon in this image taken by the panoramic camera (Pancam) on NASA's Mars Exploration Rover Opportunity on March 8, 2009, during the 1,821st Martian day, or sol, of the rover's mission on Mars.
That portion of Endeavour's rim is about 34 kilometers (21 miles) away from Opportunity's position west of the crater when the image was taken. The width of the image covers approximately one degree of the horizon.
North Rim of Endeavour Crater on Horizon
NASA Technical Reports Server (NTRS)
2009-01-01
[figure removed for brevity, see original site]
A northern portion of the rim of Endeavour Crater is visible on the horizon of this image taken by the panoramic camera (Pancam) on NASA's Mars Exploration Rover Opportunity on March 7, 2009, during the 1,820st Martian day, or sol, of the rover's mission on Mars.
That portion of Endeavour's rim is about 20 kilometers (12 miles) away from Opportunity's position west of the crater when the image was taken. The width of the image covers approximately one degree of the horizon.
Expanding your horizons in science and mathematics
NASA Technical Reports Server (NTRS)
1985-01-01
Through the presentation of its Expanding Your Horizons in Science and Mathematics career education conferences for secondary school young women, the Math/Science Network continues its efforts to remove the educational, psychological, and cultural barriers which prevent women from entering math-and science-based careers. The Expanding Your Horizons conferences were presented on 77 college, university and high school campuses across the United States. This year, these unique one day conferences reached 15,500 students, 3,000 parents and educators, and involved 3,000 career women who volunteered their services as conference planners, workshop leaders, speakers, and role models.
Hair-brane ideas on the horizon
NASA Astrophysics Data System (ADS)
Martinec, Emil J.; Niehoff, Ben E.
2015-11-01
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 gravity side.
Horizons and plane waves: A review
Hubeny, Veronika E.; Rangamani, Mukund
2003-11-06
We review the attempts to construct black hole/string solutions in asymptotically plane wave spacetimes. First, we demonstrate that geometries admitting a covariantly constant null Killing vector cannot admit event horizons, which implies that pp-waves can't describe black holes. However, relaxing the symmetry requirements allows us to generate solutions which do possess regular event horizons while retaining the requisite asymptotic properties. In particular, we present two solution generating techniques and use them to construct asymptotically plane wave black string/brane geometries.
Evidence for a sedimentary siloxane horizon
Pellenbarg, R.E.; Tevault, D.E.
1986-07-01
Selected samples from two Puget Sound sediment cores have been analyzed for poly(organo)siloxanes(silicones). One core was 60 years old at 30-cm depth (ages by lead-210 dating) and showed no evidence for silicones there. The second, 15 years old at depth, exhibited silicones at depth. Clearly shown is evidence for a siloxane horizon in theses two cores, with the presence of the horizon directly related to the fact that silicones have been in widespread use only since World War II. All samples were analyzed by solvent extraction and diffuse reflectance Fourier transform infrared spectrometry. 10 references, 2 figures, 1 table.
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.
Hair from the Isolated Horizon Perspective
NASA Astrophysics Data System (ADS)
Corichi, A.; Sudarsky, D.
2002-12-01
The recently introduced Isolated Horizons (IH) formalism has become a powerful tool for realistic black hole physics. In particular, it generalizes the zeroth and first laws of black hole mechanics in terms of quasi-local quantities and serves as a starting point for quantum entropy calculations. In this note we consider theories which admit hair, and analyze some new results that the IH provides, when considering solitons and stationary solutions. Furthermore, the IH formalism allows to state uniqueness conjectures (i.e. horizon 'no-hair conjectures') for the existence of solutions.
Expanding Horizons of Health Cares
... about who uses CAM, how it can alleviate low back pain, how an ancient Chinese treatment works for some ... Progress / Acupuncture From Ancient Practice to Modern Science / Low Back Pain and CAM / Time to Talk / Quiz on Complementary ...
The New Horizons Radio Science Experiment (REX)
NASA Astrophysics Data System (ADS)
Tyler, G. L.; Linscott, I. R.; Bird, M. K.; Hinson, D. P.; Strobel, D. F.; Pätzold, M.; Summers, M. E.; Sivaramakrishnan, K.
2008-10-01
The New Horizons (NH) Radio Science Experiment, REX, is designed to determine the atmospheric state at the surface of Pluto and in the lowest few scale heights. Expected absolute accuracies in n, p, and T at the surface are 4ṡ1019 m-3, 0.1 Pa, and 3 K, respectively, obtained by radio occultation of a 4.2 cm- λ signal transmitted from Earth at 10-30 kW and received at the NH spacecraft. The threshold for ionospheric observations is roughly 2ṡ109 e- m-3. Radio occultation experiments are planned for both Pluto and Charon, but the level of accuracy for the neutral gas is expected to be useful at Pluto only. REX will also measure the nightside 4.2 cm- λ thermal emission from Pluto and Charon during the time NH is occulted. At Pluto, the thermal scan provides about five half-beams across the disk; at Charon, only disk integrated values can be obtained. A combination of two-way tracking and occultation signals will determine the Pluto system mass to about 0.01 percent, and improve the Pluto-Charon mass ratio. REX flight equipment augments the NH radio transceiver used for spacecraft communications and tracking. Implementation of REX required realization of a new CIC-SCIC signal processing algorithm; the REX hardware implementation requires 1.6 W, and has mass of 160 g in 520 cm3. Commissioning tests conducted after NH launch demonstrate that the REX system is operating as expected.
NASA Astrophysics Data System (ADS)
Schindhelm, Eric
2014-10-01
The New Horizons spacecraft will perform the first-ever, and the only planned flyby of the Pluto System, in July 2015. It will observe Pluto and its moons from Far-Ultraviolet (FUV) to radio wavelengths. However, between 1870 and 4200 Angstroms there is no spectral coverage aboard New Horizons. The Mid-Ultraviolet (MUV, 2000 - 3000 Angstroms), which cannot be observed from the ground, contains numerous useful indicators of surface and atmospheric composition that can provide additional constraints about Pluto. Since Pluto's MUV spectrum is known to change over time, it is scientifically important to capture such data at the unique New Horizons encounter epoch. We propose here a focused, 2-orbit STIS G230L observation of Pluto at the same sub-Earth longitude where New Horizons will obtain its best FUV spectra during its closest approach to Pluto. We note that these HST observations need not occur on the same day as the New Horizons encounter, only during the same observing season. In two orbits, STIS yields higher-SNR spectra of Pluto than have ever been obtained to date in the MUV. This will bridge the gap in New Horizons' spectral coverage, placing the FUV spectra in context with longer wavelength data and contributing new information to augment the New Horizons results with those from HST. Our main science objective is MUV spectroscopy of Pluto, however if scheduling allows for the correct roll angle to also capture Charon in the STIS 52"x2" slit, MUV surface reflectance spectra of Charon would also complement New Horizons FUV data.
Near-horizon circular orbits and extremal limit for dirty rotating black holes
NASA Astrophysics Data System (ADS)
Zaslavskii, O. B.
2015-08-01
We consider generic rotating axially symmetric "dirty" (surrounded by matter) black holes. Near-horizon circular equatorial orbits are examined in two different cases of near-extremal (small surface gravity κ ) and exactly extremal black holes. This has a number of qualitative distinctions. In the first case, it is shown that such orbits can lie as close to the horizon as one wishes on suitably chosen slices of space-time when κ →0 . This generalizes the observation of T. Jacobson [Classical Quantum Gravity 28, 187001 (2011), 10.1088/0264-9381/28/18/187001] made for the Kerr metric. If a black hole is extremal (κ =0 ), circular on-horizon orbits are impossible for massive particles but, in general, are possible in its vicinity. The corresponding black hole parameters determine also the rate with which a fine-tuned particle on the noncircular near-horizon orbit asymptotically approaches the horizon. Properties of orbits under discussion are also related to the Bañados-Silk-West effect of high energy collisions near black holes. Impossibility of the on-horizon orbits in question is manifestation of kinematic censorship that forbids infinite energies in collisions.
Space Launch Initiative: New Capabilities ... New Horizons
NASA Technical Reports Server (NTRS)
Dumbacher, Daniel L.
2002-01-01
This paper presents NASA's Space Launch Initiative (SLI) with new capabilities and new horizons. The topics include: 1) Integrated Space Transportation Plan; 2) SLI: The Work of an Nation; 3) SLI Goals and Status; 4) Composites and Materials; and 5) SLI & DoD/USAF Collaboration. This paper is presented in viewgraph form.
Space Launch Initiative: New Capabilities - New Horizons
NASA Technical Reports Server (NTRS)
Dumbacher, Daniel; Smith, Dennis E. (Technical Monitor)
2002-01-01
This paper presents NASA's Space Launch Initiative (SLI) with new capabilities and new horizons. The topics include: 1) Integrated Space Transportation Plan; 2) SLI: The Work of a Nation; 3) SLI Goals and Status; 4) Composites and Materials; and 5) SLI and DOD/USAF Collaboration. This paper is in viewgraph form.
Automatic star-horizon angle measurement system
NASA Technical Reports Server (NTRS)
Koerber, K.; Koso, D. A.; Nardella, P. C.
1969-01-01
Automatic star horizontal angle measuring aid for general navigational use incorporates an Apollo type sextant. The eyepiece of the sextant is replaced with two light detectors and appropriate circuitry. The device automatically determines the angle between a navigational star and a unique point on the earths horizon as seen on a spacecraft.
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…
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…
New Horizons in Mathematics and Science Education.
ERIC Educational Resources Information Center
Thorson, Annette, Ed.
2001-01-01
This journal, intended for classroom teachers, provides a collection of essays organized around the theme of new horizons in mathematics and science education as well as a guide to instructional materials related to the theme. Topics addressed in the essays include digital libraries, the future of science curricula, integrated curricula, and…
Agriculture’s Ethical Horizon, book review
Technology Transfer Automated Retrieval System (TEKTRAN)
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...
Vegetarianism. New Horizons in Nutrition.
ERIC Educational Resources Information Center
Arnold, Justine; Grogan, Jane, Ed.
This instructional handbook is one of a series of ten packets designed to form a comprehensive course in nutrition for secondary students. This unit examines the vegetarian diet as a viable alternative, and at the same time, it introduces the topics of protein and vitamin B12. It contains a page of teaching suggestions, a pre-test for the…
Prediction horizon effects on stochastic modelling hints for neural networks
Drossu, R.; Obradovic, Z.
1995-12-31
The objective of this paper is to investigate the relationship between stochastic models and neural network (NN) approaches to time series modelling. Experiments on a complex real life prediction problem (entertainment video traffic) indicate that prior knowledge can be obtained through stochastic analysis both with respect to an appropriate NN architecture as well as to an appropriate sampling rate, in the case of a prediction horizon larger than one. An improvement of the obtained NN predictor is also proposed through a bias removal post-processing, resulting in much better performance than the best stochastic model.
The Pluto System As Seen By New Horizons Spacecraft
The Pluto system as NASA’s New Horizons spacecraft saw it in July 2015. This animation, made with real images taken by New Horizons, begins with Pluto flying in for its close-up on July 14; we then...
SETAC launches global horizon scanning/research prioritization project
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 ...
New horizons in osteoporosis therapies.
Harsløf, Torben; Langdahl, Bente L
2016-06-01
Efficient therapies are available for the treatment of osteoporosis, however, there are still unmet needs. Anti-resorptive therapies only increase bone mineral density to a certain extent and reduce the risk of non-vertebral fractures by 20%, only one anabolic option is available-the effect of which levels off over time, and the evidence for combination therapy targeting both resorption and formation is limited. The current review will focus on emerging treatments of osteoporosis with the potential of enhanced anabolic effects (romosozumab and abaloparatide) or uncoupling of resorption and formation (odanacatib and romosozumab) as well as the effect of combination therapy. PMID:26989807
The dogger reef horizons of the Moroccan Central High Atlas: New data on their development
NASA Astrophysics Data System (ADS)
Ait Addi, Abdellah
2006-06-01
In the Central High Atlas, N of Errachidia, three major reef horizons in the Bajocian carbonate series of the Atlasic Basin were studied recently. The results of the study are based on fieldwork with an emphasis on stratigraphy, morphology and sedimentary patterns of detailed field sections. The lower reef horizon is composed of smaller build-ups which developed during the Aalenian-Lower Bajocian interval. At that time the depositional environment favored the production of both basinal and platform facies. This reef horizon is located only on the southern platform rim. Its development within the trough was controlled by synsedimentary block tilting, triggered by rifting, which was related to an ancient fracture zones inherited from the Triassic. Formed during the later stages of a rising sea-level, this horizon reflects a high carbonate production on the southern platform area. In the basin area, the second reef horizon presents relatively larger bodies (" patch reefs"). It consists of two major reef levels, separated by an interval of marls interspersed with thin-bedded limestones, developed most probably during Early? to Late Bajocian. For the duration of this time, within two 3rd order sequences, progradational shelfal units extended the platform facies northward to the basin center, covering a large area. Within a long-term transgressive/regressive cycle, throughout the Middle Aalenian-Bajocian, these reef horizons changed their structural growth to aggrading stacking patterns. The third reef horizon belongs to the lower part of the upper member of the Tazigzaout Formation, and shows the same sedimentary evolution as the second reef horizon underneath. It fits into a 2nd order geodynamic regressive cycle (upper part of Upper Bajocian-Bathonian pp.). It appears, that the development of the second and third reef horizon's forced the platform to prograde towards the N, NW and E during a late highstand, when accommodation was decreasing. However, depending on the
Rindler-like Horizon in Spherically Symmetric Spacetime
NASA Astrophysics Data System (ADS)
Yang, Jinbo; He, Tangmei; Zhang, Jingyi
2016-02-01
In this paper, the Rindler-like horizon in a spherically symmetric spacetime is proposed. It is showed that just like the Rindler horizon in Minkowski spacetimes, there is also a Rindler-like horizon to a family of special observers in general spherically symmetric spacetimes. The entropy of this type of horizon is calculated with the thin film brick-wall model. The significance of entropy is discussed. Our results imply some connection between Bekeinstein-Hawking entropy and entanglement entropy.
Rindler-like Horizon in Spherically Symmetric Spacetime
NASA Astrophysics Data System (ADS)
Yang, Jinbo; He, Tangmei; Zhang, Jingyi
2016-07-01
In this paper, the Rindler-like horizon in a spherically symmetric spacetime is proposed. It is showed that just like the Rindler horizon in Minkowski spacetimes, there is also a Rindler-like horizon to a family of special observers in general spherically symmetric spacetimes. The entropy of this type of horizon is calculated with the thin film brick-wall model. The significance of entropy is discussed. Our results imply some connection between Bekeinstein-Hawking entropy and entanglement entropy.
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
Kimura, Masashi
2008-08-15
We show that there exist five-dimensional multi-black hole solutions which have analytic event horizons when the space-time has nontrivial asymptotic structure, unlike the case of five-dimensional multi-black hole solutions in asymptotically flat space-time.
Rogue events in the group velocity horizon
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 ratio bound for inflationary fluctuations.
Dodelson, Scott; Hui, Lam
2003-09-26
We demonstrate that the gravity wave background amplitude implies a robust upper bound on the wavelength-to-horizon ratio at the end of inflation: lambda/H(-1) less than or approximately equal e(60), as long as the cosmic energy density does not drop faster than radiation subsequent to inflation. This limit implies that N, the number of e-folds between horizon exit and the end of inflation for wave modes of interest, is less, similar 60 plus a model-dependent factor-for vast classes of slow-roll models, N less than or approximately equal 67. As an example, this bound solidifies the tension between observations of the cosmic microwave background anisotropies and chaotic inflation with a phi(4) potential by closing the escape hatch of large N (<62). PMID:14525296
Horizon Missions Technology Study. [for space exploration
NASA Technical Reports Server (NTRS)
Anderson, John L.
1992-01-01
The purpose of the HMT Study was to develop and demonstrate a systematic methodology for identifying and evaluating innovative technology concepts offering revolutionary, breadkthrough-type capabilities for advanced space missions and for assessing their potential mission impact. The methodology is based on identifying the new functional, operational and technology capabilities needed by hypothetical 'Horizon' space missions that have performance requirements that cannot be met, even by extrapolating known space technologies. Nineteen Horizon Missions were selected to represent a collective vision of advanced space missions of the mid-21st century. The missions typically would occur beyond the lifetime of current or planned space assets. The HM methodology and supporting data base may be used for advanced technology planning, advanced mission planning and multidisciplinary studies and analyses.
Horizon crossing and inflation with large {eta}
Kinney, William H.
2005-07-15
I examine the standard formalism of calculating curvature perturbations in inflation at horizon crossing, and derive a general relation which must be satisfied for the horizon-crossing formalism to be valid. This relation is satisfied for the usual cases of power-law and slow-roll inflation. I then consider a model for which the relation is strongly violated, and the curvature perturbation evolves rapidly on superhorizon scales. This model has Hubble slow-roll parameter {eta}=3, but predicts a scale-invariant spectrum of density perturbations. I consider the case of hybrid inflation with large {eta}, and show that such solutions do not solve the '{eta} problem' in supergravity. These solutions correspond to field evolution which has not yet relaxed to the inflationary attractor solution, and may make possible new, more natural models on the string landscape.
Finding apparent horizons in numerical relativity
NASA Astrophysics Data System (ADS)
Thornburg, Jonathan
1996-10-01
We review various algorithms for finding apparent horizons in 3+1 numerical relativity. We then focus on one particular algorithm, in which we pose the apparent horizon equation H≡∇ini+Kijninj-K=0 as a nonlinear elliptic (boundary-value) PDE on angular-coordinate space for the horizon shape function r=h(θ,φ), finite difference this PDE, and use Newton's method or a variant to solve the finite difference equations. We describe a method for computing the Jacobian matrix of the finite differenced H(h) sH (sh) function by symbolically differentiating the finite difference equations, giving the Jacobian elements directly in terms of the finite difference molecule coefficients used in computing sH (sh). Assuming the finite differencing scheme commutes with linearization, we show how the Jacobian elements may be computed by first linearizing the continuum H(h) equations, then finite differencing the linearized continuum equations. (This is essentially just the ``Jacobian part'' of the Newton-Kantorovich method for solving nonlinear PDEs.) We tabulate the resulting Jacobian coefficients for a number of different sH (sh) and Jacobian computation schemes. We find this symbolic differentiation method of computing the Jacobian to be much more efficient than the usual numerical-perturbation method, and also much easier to implement than is commonly thought. When solving the discrete sH (sh)=0 equations, we find that Newton's method generally shows robust convergence. However, we find that it has a small (poor) radius of convergence if the initial guess for the horizon position contains significant high-spatial-frequency error components, i.e., angular Fourier components varying as (say) cosmθ with m>~8. (Such components occur naturally if spacetime contains significant amounts of high-frequency gravitational radiation.) We show that this poor convergence behavior is not an artifact of insufficient resolution in the finite difference grid; rather, it appears to be caused
Transformation of polymetallic dust in the organic horizon of Al-Fe-humus podzol (field experiment)
NASA Astrophysics Data System (ADS)
Lyanguzova, I. V.; Goldvirt, D. K.; Fadeeva, I. K.
2015-07-01
Scanning electron microscopy with an X-ray spectral microanalysis showed that the ash matter from the organic horizons (after ignition) of control and experimental plots mainly (>85%) consists of different soil-forming minerals and iron oxides (particularly magnetite). From 10% to 15% of particles in the organic horizon of Al-Fe-humus podzol (Albic Rustic Podzol) of the experimental plot were represented by polymetallic ball-shaped dust particles that were preserved in the soil without significant transformation for 14 years after their artificial application. The total contents of Cu, Pb, As, and Ni in the organic horizon on the experimental plot were 22-100 times higher than those in the control; the contents of Zn and Fe were 2-5 times higher. The sequence of chemical elements according to their total contents in the samples of control and experimental plots was different. The portion of available forms of heavy metal (Ni, Cu, and Co) compounds extractable with 1.0 M HCl averaged 20-30% of their total contents in the soil. More than 80% of acid-soluble forms of heavy metals were concentrated in the organic horizon of contaminated podzol soil, which represents the biogeochemical barrier to the migration of pollutants down the soil profile. Durable fixation of heavy metals in the organic horizon and their weak migration into the mineral soil layers significantly hamper the processes of self-purification of contaminated soils.
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
2014-02-01
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. This 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 three objects that could be targeted with only about 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 in 2014, taking advantage of lower star density and the shrinking search area, has a good chance of finding a targetable object given sufficiently good seeing, especially with Hyper Suprime Cam. We expect about 2.5 targetable objects with R less 26.0 in the HSC field of view. We will also refine the orbits of previously discovered objects, including ones that can be observed from a distance by New Horizons on its passage through the Kuiper Belt.
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.
Horizon Science Experiment for Mars Global Surveyor
NASA Astrophysics Data System (ADS)
Martin, T. Z.
1997-07-01
The Mars Horizon Sensor Assembly on the MGS orbiter monitors the orientation of the spacecraft relative to the limb by sensing atmospheric emission in the 15 mu m CO2 band. These data are used to maintain nadir pointing for the remote sensing instrument suite. The set of 5.5deg tall triangular fields of view normally straddle the limb, and cover quadrants 90deg apart around the limb. As an engineering device, the MHSA benefits from Mars' atmosphere being spatially bland at 15 mu m. However, these data will carry information about the thermal state of the atmosphere, which is subject to diurnal, seasonal, latitudinal, and dust-storm related variations, as well as possible wave effects. The Mariner 7 IRS, Mariner 9 IRIS, and Viking IRTM all demonstrated such variability. The Horizon Science Experiment (HORSE) is intended to glean new insight into atmospheric variation from the MGS horizon sensors, with continuous data flow to the Earth in the engineering stream, and a rapid buildup of spatial coverage. MHSA data will also be used to monitor atmospheric thermal behavior during the aerobraking of MGS in late 1997.
The Tookoonooka marine impact horizon, Australia: Sedimentary and petrologic evidence
NASA Astrophysics Data System (ADS)
Bron, Katherine A.; Gostin, Victor
2012-02-01
Ejecta from the large subsurface Tookoonooka impact structure have been found in the Lower Cretaceous strata of the extensive Eromanga Basin of central Australia. Observations from 31 wells spanning 400,000 km2 of the basin provide compelling evidence for the presence of a marine impact horizon of regional extent. Drill core was examined to determine the sedimentary context of the Tookoonooka impact event, the presence of ejecta, and the nature of the impact horizon. The base of the Wyandra Sandstone Member of the Cadna-owie Formation is an unconformity commonly overlain by very poorly sorted sediment with imbricated pebbles, exotic clasts, and occasional boulders. The basal Wyandra Sandstone Member is bimodal: a fine sand mode reflects an ambient sediment contribution and a coarse mode is interpreted to be impact-derived. Wells Thargomindah-1 and Eromanga-1, within four crater radii of Tookoonooka, contain distinctive clast-supported breccia-conglomerate beds at the base of the Wyandra Sandstone Member. Clasts in these beds include altered accretionary and melt impactoclasts, as well as lithic and mineral grains corresponding to the Tookoonooka target rock sequence, including basement. Petrographic evidence includes shock metamorphosed quartz and lithic grains with planar deformation features. These breccia-conglomerates are in stark contrast to the underlying, laterally persistent, unimodal Cadna-owie sediments and overlying shales deposited in an epeiric sea. The base of the Wyandra Sandstone Member is therefore interpreted to be the Tookoonooka impact horizon. The timing of the impact event is confirmed to be the Barremian-Aptian boundary, at 125 ± 1 Ma. The Wyandra Sandstone Member preserves both impact ejecta and postimpact marine sediments.
Is the Gravitational-Wave Ringdown a Probe of the Event Horizon?
NASA Astrophysics Data System (ADS)
Cardoso, Vitor; Franzin, Edgardo; Pani, Paolo
2016-04-01
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.
Is the Gravitational-Wave Ringdown a Probe of the Event Horizon?
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. PMID:27176511
Xu, Hao; Jagannathan, Sarangapani
2015-03-01
The stochastic optimal control of nonlinear networked control systems (NNCSs) using neuro-dynamic programming (NDP) over a finite time horizon is a challenging problem due to terminal constraints, system uncertainties, and unknown network imperfections, such as network-induced delays and packet losses. Since the traditional iteration or time-based infinite horizon NDP schemes are unsuitable for NNCS with terminal constraints, a novel time-based NDP scheme is developed to solve finite horizon optimal control of NNCS by mitigating the above-mentioned challenges. First, an online neural network (NN) identifier is introduced to approximate the control coefficient matrix that is subsequently utilized in conjunction with the critic and actor NNs to determine a time-based stochastic optimal control input over finite horizon in a forward-in-time and online manner. Eventually, Lyapunov theory is used to show that all closed-loop signals and NN weights are uniformly ultimately bounded with ultimate bounds being a function of initial conditions and final time. Moreover, the approximated control input converges close to optimal value within finite time. The simulation results are included to show the effectiveness of the proposed scheme. PMID:25720004
Chandra Uncovers New Evidence For Event Horizons Surrounding Black Holes
NASA Astrophysics Data System (ADS)
2001-01-01
horizon is the defining characteristic of a black hole, but obviously it is very difficult to detect since any infalling material at the event horizon is observable for only an instant as it plunges inward at the speed of light," said McClintock. "The comparison of black holes and their close cousins, the neutron stars, may be the most promising way to get a handle on the event horizon." If the collapsed star is a neutron star with a solid surface, energy must be released when infalling matter strikes that surface. In contrast, if the accreting object is a black hole, there is no surface for the matter to strike. Instead, both the energy and the matter will be lost from view forever once they cross the event horizon. A small amount of energy can escape just before the matter crosses the event horizon, but the scientists believe that it should be much less than the energy released by matter hitting a neutron star surface. "Watching matter flowing into a black hole is like sitting upstream of a waterfall and watching the water seemingly vanish over the edge," said Narayan, chairman of the Harvard Astronomy Department. "However, if the waterfall were replaced by a dam -- the analog of a neutron star surface -- then the water would pile up and one would see a mighty lake". Why are dormant black hole sources a hundred times fainter than the neutron star sources? The amount of material falling towards the collapsed star and the subsequent energy release are believed to be nearly the same, whether the compact object is a black hole or a neutron star. Therefore, the remarkable difference in brightness comes, according to the team, because of the event horizon, where the inward pull of gravity becomes infinitely strong. This is in contrast to the situation of neutron stars that have a more normal surface. By observing the motion of the companion star in an X-ray nova, the mass of the collapsed star can be estimated. In some cases, this mass is more than three times that of the Sun
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
Testing numerically the null Cauchy horizon singularity inside Kerr black holes
NASA Astrophysics Data System (ADS)
Burko, Lior; Khanna, Gaurav; Zenginoĝlu, Anil
2015-04-01
The Cauchy horizon inside a Kerr black hole develops an instability that transforms it into a curvature singularity. Perturbative analyses are consistent with the picture arising from fully nonlinear simulations of spherical charged black holes: this singularity is deformational weak and null for early retarded times. Despite much interest in this long-standing problem, no numerical simulations of the interior of a perturbed Kerr black hole have been done to date. Here, we report on preliminary results obtained from a linear simulation of the evolution of the fields under the collapse of a test wave packet. We use recent developments to a Teukolsky equation solver, which use (event) horizon-penetrating, hyperboloidal coordinates, which compactify null infinity and penetrate through both horizons. This numerical technology allows us to penetrate through the event horizon, and probe the fields on the approach to the Cauchy horizon singularity. We study the behavior of the Weyl scalars ψ0 and ψ4 and of the curvature scalar RαβγδRαβγδ , and confront our results with those of perturbation analysis. Our results may be useful when planning fully nonlinear numerical studies of rotating black hole interiors.
NASA Astrophysics Data System (ADS)
Xie, Zhi-Kun; Pan, Wei-Zhen; Yang, Xue-Jun
2013-03-01
Using a new tortoise coordinate transformation, we discuss the quantum nonthermal radiation characteristics near an event horizon by studying the Hamilton-Jacobi equation of a scalar particle in curved space-time, and obtain the event horizon surface gravity and the Hawking temperature on that event horizon. The results show that there is a crossing of particle energy near the event horizon. We derive the maximum overlap of the positive and negative energy levels. It is also found that the Hawking temperature of a black hole depends not only on the time, but also on the angle. There is a problem of dimension in the usual tortoise coordinate, so the present results obtained by using a correct-dimension new tortoise coordinate transformation may be more reasonable.
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.
Lagrangian Predictive Skill Assessment for the Deepwater Horizon Spill
NASA Astrophysics Data System (ADS)
Lipphardt, B. L.; Huntley, H. S.; Sulman, M.; Kirwan, A. D.
2011-12-01
The explosion and sinking of the Deepwater Horizon drilling platform produced enormous human, ecological, and economic impacts. At the same time this disaster provided an unprecedented amount of Lagrangian information on ocean processes, including a large number of surface and near-surface drifters deployed in the northeastern Gulf of Mexico as well as remotely sensed images of the surface oil slick. In addition several global and regional ocean model predictions were used to forecast the spill movements. These models generally exhibited large variations in the mesoscale flow near the Deepwater Horizon site, even though they all assimilated similar sets of ocean observations. This provides a unique opportunity to thoroughly assess model Lagrangian predictive skill. Here, the predictive skill of one model, a regional implementation of the Hybrid Coordinate Ocean Model (HYCOM), is evaluated using data from more than 80 drifter trajectories in the northern Gulf of Mexico. These trajectories are compared with maps of Lagrangian coherent structures, computed from near-surface model velocities, to determine whether the observations are consistent with the larger scale transport structure predicted by the model. We also discuss new metrics to assess model Lagrangian predictive skill of the plume movement.
First Results from the Mars Global Surveyor Horizon Science Experiment
NASA Astrophysics Data System (ADS)
Martin, Terry
1998-09-01
The Horizon Science Experiment (HORSE) uses the Mars Horizon Sensor Assembly on the MGS orbiter to measure 15 micrometer band thermal emission from the Martian atmosphere. During the first phase of aerobraking for MGS, from September 1997 through March 1998, one of the four MGS quadrants was pointed well onto the planet consistently during the near-periapsis braking passes, allowing the device to obtain data on the latitudinal variation of middle atmospheric temperature (0.2 - 2 mbar). Of particular interest were the effects of a prominent dust storm at Ls 224, and the strong gradient of temperature near the north polar cap. The dust storm produced 10-12K warming in the middle atmosphere across the latitude range from -50 to +60 degrees over a time period of 97 hrs. The increase was most pronounced at the longitudes near 330 where the storm originated in the southern hemisphere. During Ls 260-278, the latitude of steepest latitudinal temperature gradient (the location of the northern polar vortex) varied with longitude in a primarily wave 2 mode, with an amplitude of about 8 degrees and one maximum at 120 longitude. A small wave 1 term is also present.
Observation of an optical event horizon in a silicon-on-insulator photonic wire waveguide.
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. PMID:26832243
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
The horizon of the lightest black hole
NASA Astrophysics Data System (ADS)
Calmet, Xavier; Casadio, Roberto
2015-09-01
We study the properties of the poles of the resummed graviton propagator obtained by resumming bubble matter diagrams which correct the classical graviton propagator. These poles have been previously interpreted as black holes precursors. Here, we show using the horizon wave-function formalism that these poles indeed have properties which make them compatible with being black hole precursors. In particular, when modeled with a Breit-Wigner distribution, they have a well-defined gravitational radius. The probability that the resonance is inside its own gravitational radius, and thus that it is a black hole, is about one half. Our results confirm the interpretation of these poles as black hole precursors.
Peripheral Vision Horizon Display (PVHD). Corrected Copy
NASA Technical Reports Server (NTRS)
1984-01-01
A Canadian invention, the peripheral vision horizon display (PVHD), shows promise in alleviating vertigo or disorientation in pilots flying under instrument conditions and easing the piloting task when flying in weather or other conditions requiring close attention to aircraft attitude instruments. A diversity of research and applied work was being done to investigate and validate the benefits of the PVHD during the years immediately preceding this conference. Organizers of the conference were able to assemble a group of outstanding presenters representing academic, industrial, and military. The theoretical foundation and applied use of the PVHD are discussed, and results from operational tests are presented.
Prolate horizons and the Penrose inequality
Tippett, Benjamin K.
2009-05-15
The Penrose inequality has so far been proven in cases of spherical symmetry and in cases of zero extrinsic curvature. The next simplest case worth exploring would be nonspherical, nonrotating black holes with nonzero extrinsic curvature. Following Karkowski et al.'s construction of prolate black holes, we define initial data on an asymptotically flat spacelike 3-surface with nonzero extrinsic curvature that may be chosen freely. This gives us the freedom to define the location of the apparent horizon such that the Penrose inequality is violated. We show that the dominant energy condition is violated at the poles for all cases considered.
Black hole thermodynamics from Euclidean horizon constraints.
Carlip, S
2007-07-13
To explain black hole thermodynamics in quantum gravity, one must introduce constraints to ensure that a black hole is actually present. I show that for a large class of black holes, such "horizon constraints" allow the use of conformal field theory techniques to compute the density of states, reproducing the Bekenstein-Hawking entropy in a nearly model-independent manner. One standard string theory approach to black hole entropy arises as a special case, lending support to the claim that the mechanism may be "universal." I argue that the relevant degrees of freedom are Goldstone-boson-like excitations arising from the weak breaking of symmetry by the constraints. PMID:17678209
European scientists' proposals for HORIZON 2000+
NASA Astrophysics Data System (ADS)
1994-10-01
This programme, which has been given the name Horizon 2000+, will be presented to the press at 0900h on Monday 17 October 1994 at ESA Headquarters in Paris by Professor Lodewijk Woltjer, who chaired the committee of European scientific community representatives set up to consider the proposals submitted, and Professor Roger Bonnet, ESA's Science Programme Director. Journalists wishing to attend this press breakfast are requested to complete and return the attached form, if possible by fax: (33.1) 42.73.76.90.
Preferential Flow Paths Allow Deposition of Mobile Organic Carbon Deep into Soil B Horizons
NASA Astrophysics Data System (ADS)
Marin-Spiotta, E.; Chadwick, O.; Kramer, M. G.
2009-12-01
Most of our understanding of soil carbon (C) dynamics derives from the top 10 to 20 cm, although globally the majority of the bulk soil C pool is found below those depths. Mineral associated C in deep soil is more stable than that held in surface horizons, and its long-term persistence may contribute to sequestration of anthropogenic C. Carbon can enter deep soil horizons in multiple ways: through biologically-mediated or abiotic physical mixing, illuviation, root inputs, or through a physical disturbance that would cause the burial of an originally shallow organic horizon. In this study, we investigated the role of dissolved organic matter (DOM) in the transport and stabilization of soil C in tropical rainforest volcanic soils, where high rainfall, a highly productive forest, and dominance of highly reactive, non-crystalline minerals contribute to large soil C stocks at depth with long mean residence times. DOM plays an important role in many biological and chemical processes in soils, including nutrient transfer within and across ecosystems. Carbon storage in these soils is linked to movement of both DOC and particulate organic C along infiltration pathways. Climate and soil mineralogical properties create the right conditions for C to be pumped from the organic horizons where microbial activity is highest, to deep mineral horizons, where the potential for stabilization is greatest. High rainfall preserves hydrated short-range order minerals that are subject to strong shrinkage during occasional drought periods. The resulting cracks in subsurface B horizons become pathways for DOM complexed with Fe and Al moving in soil solution during subsequent wet periods. Preferential flow of these organically rich solutes and/or colloids moves C to depth where C, Fe and Al are preferentially deposited on near-vertical crack surfaces and along near-horizonal flow surfaces at horizon boundaries. Long-term deposition forms discontinuous Fe- and OM-cemented lamella that serve to
Projecting Program Cost Over an Adequate Time Horizon.
ERIC Educational Resources Information Center
Spencer, Milton
Planning Programming Budgeting Systems involve the introduction of three major operational concepts. First, the development of an analytical capability to examine in depth both agency objectives and the various programs to meet these objectives. Second, the formation of a five-year planning and programming process combined with a sophisticated…
Time horizon for AFV emission savings under Tier 2
Saricks, C. L.
2000-03-20
Implementation of the Federal Tier 2 vehicular emission standards according to the schedule presented in the December, 1999 Final Rule will result in substantial reductions of NMHC, CO, NO{sub x}, and fine particle emissions from motor vehicles. Currently, when compared to Tier 1 and even NLEV certification requirements, the emissions performance of automobiles and light-duty trucks powered by non-petroleum (especially, gaseous) fuels (i.e., vehicles collectively termed AFVs) enjoy measurable advantage over their gasoline- and diesel-fueled counterparts over the full Federal Test Procedure and, especially, in Bag 1 (cold start). For the lighter end of these vehicle classes, this advantage may disappear shortly after 2004 under the new standards, but should continue for a longer period (perhaps beyond 2008) for the heavier end as well as for heavy-duty vehicles relative to diesel-fueled counterparts. Because of the continuing commitment of the U.S. Department of Energy's Clean Cities coalitions to the acquisition and operation of AFVs of many types and size classes, it is important for them to know in which classes their acquisitions will remain clear relative to the petroleum-fueled counterparts they might otherwise procure. This paper provides an approximate timeline for and expected magnitude of such savings, assuming that full implementation of the Tier 2 standards covering both vehicular emissions and fuel sulfur limits proceeds on schedule. The pollutants of interest are primary ozone precursors and fine particulate matter from fuel combustion.
Acceleration of a Static Observer Near the Event Horizon of a Static Isolated Black Hole.
ERIC Educational Resources Information Center
Doughty, Noel A.
1981-01-01
Compares the magnitude of the proper acceleration of a static observer in a static, isolated, spherically symmetric space-time region with the Newtonian result including the situation in the interior of a perfect-fluid star. This provides a simple physical interpretation of surface gravity and illustrates the global nature of the event horizon.…
ALUMINUM PRECIPITATION AND DISSOLUTION RATES IN SPODOSOL BS HORIZONS IN THE NORTHEASTERN USA
The kinetics of Al precipitation/dissolution reactions in Spodosol Bs horizons from sites at Hubbard Brook, NH and Bear Brook, ME were examined. echanical vacuum extractor was employed to draw solutions through soil columns at solution/soil residence times between 0.3 and 100 h. ...
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
.... Applicants currently intend that the initial series of the Trust will be the Horizons Active Global Dividend... through either the NSCC or DTC; or (ii) in the case of Funds holding non-U.S. investment (``Global Funds... holder of Shares of a Global Fund would be subject to unfavorable income tax treatment if the...
Killing horizons around a uniformly accelerating and rotating particle
Farhoosh, H.; Zimmerman, R.L.
1980-08-15
The structure of the Killing horizon surrounding a uniformly accelerating and rotating particle which is emitting gravitational radiation is investigated. When expressed in terms of a coordinate system which is rigidly fixed to the particle undergoing uniform acceleration, the two inner horizons and ergoregion are similar to the horizons and ergoregion in the Kerr solution. These compact surfaces are distorted by the acceleration, being elongated in the forward direction and contracted in the backward direction. In addition to the two horizons that are similar to the Kerr solution, there is an additional noncompact horizon and an additional ergoregion which are caused by the acceleration. In general, the two ergoregions are disjoint, but as the acceleration parameter is sufficiently increased these ergoregions coalesce. A further increase of the acceleration will cause the two outer horizons to become degenerate and the ergoregion to vanish. An increase in the rotation parameter causes effects similar to those in the Kerr metric.
Killing horizons around a uniformly accelerating and rotating particle
NASA Astrophysics Data System (ADS)
Farhoosh, Hamid; Zimmerman, Robert L.
1980-08-01
The structure of the Killing horizon surrounding a uniformly accelerating and rotating particle which is emitting gravitational radiation is investigated. When expressed in terms of a coordinate system which is rigidly fixed to the particle undergoing uniform acceleration, the two inner horizons and ergoregion are similar to the horizons and ergoregion in the Kerr solution. These compact surfaces are distorted by the acceleration, being elongated in the forward direction and contracted in the backward direction. In addition to the two horizons that are similar to the Kerr solution, there is an additional noncompact horizon and an additional ergoregion which are caused by the acceleration. In general, the two ergoregions are disjoint, but as the acceleration parameter is sufficiently increased these ergoregions coalesce. A further increase of the acceleration will cause the two outer horizons to become degenerate and the ergoregion to vanish. An increase in the rotation parameter causes effects similar to those in the Kerr metric.
Gribov's horizon and the ghost dressing function
Boucaud, Ph.; Leroy, J. P.; Le Yaouanc, A.; Micheli, J.; Pene, O.; Rodriguez-Quintero, J.
2009-11-01
We study a relation recently derived by K. Kondo at zero momentum between the Zwanziger's horizon function, the ghost dressing function and Kugo's functions u and w. We agree with this result as far as bare quantities are considered. However, assuming the validity of the horizon gap equation, we argue that the solution w(0)=0 is not acceptable since it would lead to a vanishing renormalized ghost dressing function. On the contrary, when the cutoff goes to infinity, u(0){yields}{infinity}, w(0){yields}-{infinity} such that u(0)+w(0){yields}-1. Furthermore w and u are not multiplicatively renormalizable. Relaxing the gap equation allows w(0)=0 with u(0){yields}-1. In both cases the bare ghost dressing function, F(0,{lambda}), goes logarithmically to infinity at infinite cutoff. We show that, although the lattice results provide bare results not so different from the F(0,{lambda})=3 solution, this is an accident due to the fact that the lattice cutoffs lie in the range 1-3 GeV{sup -1}. We show that the renormalized ghost dressing function should be finite and nonzero at zero momentum and can be reliably estimated on the lattice up to powers of the lattice spacing; from published data on a 80{sup 4} lattice at {beta}=5.7 we obtain F{sub R}(0,{mu}=1.5 GeV){approx_equal}2.2.
Energy and information near black hole horizons
Freivogel, Ben
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 falling 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.
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.
Radiation from quantum weakly dynamical horizons in loop quantum gravity.
Pranzetti, Daniele
2012-07-01
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. PMID:23031096
Dynamical horizons: energy, angular momentum, fluxes, and balance laws.
Ashtekar, Abhay; Krishnan, Badri
2002-12-23
Dynamical horizons are considered in full, nonlinear general relativity. Expressions of fluxes of energy and angular momentum carried by gravitational waves across these horizons are obtained. Fluxes are local, the energy flux is positive, and change in the horizon area is related to these fluxes. The flux formulas also give rise to balance laws analogous to the ones obtained by Bondi and Sachs at null infinity and provide generalizations of the first and second laws of black-hole mechanics. PMID:12484807
Yi, Richard; Carter, Anne E.; Landes, Reid D.
2014-01-01
Methamphetamine users (MAU) exhibit an exaggerated bias for immediate rewards that reflects a restricted time horizon, where outcomes in the future are excessively discounted. An accumulating literature indicates that time in the future shares features with other dimensions of psychological distances including time in the past probability, and social distance, suggesting that bias for immediacy may be reducible to a more general restriction of psychological horizon. The purpose of the present study was to explore generalized restricted psychological horizon in active MAU by assessing future, past, probability, and social discounting. Compared with nonusing controls, MAU preferred psychologically proximal outcomes, resulting in higher rates for all types of discounting, which supports the conceptualization that MAU insufficiently integrate outcomes of psychological distance (i.e. in the future, the past, probabilistic, for others) into the valuation of current behavioral alternatives. The present results are suggestive of a more fundamental process of problematic decision-making associated with methamphetamine use, indicating the necessity of more comprehensive approaches to address the generalized limitations of restricted psychological horizon. PMID:22743602
Gravitational anomaly and Hawking radiation near a weakly isolated horizon
Wu Xiaoning; Huang Chaoguang; Sun Jiarui
2008-06-15
Based on the idea of the work by Wilczek and his collaborators, we consider the gravitational anomaly near a weakly isolated horizon. We find that there exists a universal choice of tortoise coordinate for any weakly isolated horizon. Under this coordinate, the leading behavior of a quite arbitrary scalar field near a horizon is a 2-dimensional chiral scalar field. This means we can extend the idea of Wilczek and his collaborators to more general cases and show the relation between gravitational anomaly and Hawking radiation is a universal property of a black hole horizon.
Gravitational anomaly and Hawking radiation near a weakly isolated horizon
NASA Astrophysics Data System (ADS)
Wu, Xiaoning; Huang, Chao-Guang; Sun, Jia-Rui
2008-06-01
Based on the idea of the work by Wilczek and his collaborators, we consider the gravitational anomaly near a weakly isolated horizon. We find that there exists a universal choice of tortoise coordinate for any weakly isolated horizon. Under this coordinate, the leading behavior of a quite arbitrary scalar field near a horizon is a 2-dimensional chiral scalar field. This means we can extend the idea of Wilczek and his collaborators to more general cases and show the relation between gravitational anomaly and Hawking radiation is a universal property of a black hole horizon.
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.
Criticality and surface tension in rotating horizon thermodynamics
NASA Astrophysics Data System (ADS)
Hansen, Devin; Kubizňák, David; Mann, Robert B.
2016-08-01
We study a modified horizon thermodynamics and the associated criticality for rotating black hole spacetimes. Namely, we show that under a virtual displacement of the black hole horizon accompanied by an independent variation of the rotation parameter, the radial Einstein equation takes a form of a ‘cohomogeneity two’ horizon first law, δ E=Tδ S+{{Ω }}δ J-σ δ A, where E and J are the horizon energy (an analogue of the Misner–Sharp mass) and the horizon angular momentum, Ω is the horizon angular velocity, A is the horizon area, and σ is the surface tension induced by the matter fields. For fixed angular momentum, the above equation simplifies and the more familiar (cohomogeneity one) horizon first law δ E=Tδ S-Pδ V is obtained, where P is the pressure of matter fields and V is the horizon volume. A universal equation of state is obtained in each case and the corresponding critical behavior is studied.
Perturbations of the Kerr spacetime in horizon-penetrating coordinates
NASA Astrophysics Data System (ADS)
Campanelli, Manuela; Khanna, Gaurav; Laguna, Pablo; Pullin, Jorge; Ryan, Michael P.
2001-04-01
We derive the Teukolsky equation for perturbations of a Kerr spacetime when the spacetime metric is written in either ingoing or outgoing Kerr-Schild form. We also write explicit formulae for setting up the initial data for the Teukolsky equation in the time domain in terms of a 3-metric and an extrinsic curvature. The motivation of this work is to have in place a formalism to study the evolution in the `close limit' of two recently proposed solutions to the initial-value problem in general relativity that are based on Kerr-Schild slicings. A perturbative formalism in horizon-penetrating coordinates is also very desirable in connection with numerical relativity simulations using black hole `excision'.
The atmosphere of Pluto as observed by New Horizons
NASA Astrophysics Data System (ADS)
Gladstone, G. Randall; Stern, S. Alan; Ennico, Kimberly; Olkin, Catherine B.; Weaver, Harold A.; Young, Leslie A.; Summers, Michael E.; Strobel, Darrell F.; Hinson, David P.; Kammer, Joshua A.; Parker, Alex H.; Steffl, Andrew J.; Linscott, Ivan R.; Parker, Joel Wm.; Cheng, Andrew F.; Slater, David C.; Versteeg, Maarten H.; Greathouse, Thomas K.; Retherford, Kurt D.; Throop, Henry; Cunningham, Nathaniel J.; Woods, William W.; Singer, Kelsi N.; Tsang, Constantine C. C.; Schindhelm, Eric; Lisse, Carey M.; Wong, Michael L.; Yung, Yuk L.; Zhu, Xun; Curdt, Werner; Lavvas, Panayotis; Young, Eliot F.; Tyler, G. Leonard; Bagenal, F.; Grundy, W. M.; McKinnon, W. B.; Moore, J. M.; Spencer, J. R.; Andert, T.; Andrews, J.; Banks, M.; Bauer, B.; Bauman, J.; Barnouin, O. S.; Bedini, P.; Beisser, K.; Beyer, R. A.; Bhaskaran, S.; Binzel, R. P.; Birath, E.; Bird, M.; Bogan, D. J.; Bowman, A.; Bray, V. J.; Brozovic, M.; Bryan, C.; Buckley, M. R.; Buie, M. W.; Buratti, B. J.; Bushman, S. S.; Calloway, A.; Carcich, B.; Conard, S.; Conrad, C. A.; Cook, J. C.; Cruikshank, D. P.; Custodio, O. S.; Ore, C. M. Dalle; Deboy, C.; Dischner, Z. J. B.; Dumont, P.; Earle, A. M.; Elliott, H. A.; Ercol, J.; Ernst, C. M.; Finley, T.; Flanigan, S. H.; Fountain, G.; Freeze, M. J.; Green, J. L.; Guo, Y.; Hahn, M.; Hamilton, D. P.; Hamilton, S. A.; Hanley, J.; Harch, A.; Hart, H. M.; Hersman, C. B.; Hill, A.; Hill, M. E.; Holdridge, M. E.; Horanyi, M.; Howard, A. D.; Howett, C. J. A.; Jackman, C.; Jacobson, R. A.; Jennings, D. E.; Kang, H. K.; Kaufmann, D. E.; Kollmann, P.; Krimigis, S. M.; Kusnierkiewicz, D.; Lauer, T. R.; Lee, J. E.; Lindstrom, K. L.; Lunsford, A. W.; Mallder, V. A.; Martin, N.; McComas, D. J.; McNutt, R. L.; Mehoke, D.; Mehoke, T.; Melin, E. D.; Mutchler, M.; Nelson, D.; Nimmo, F.; Nunez, J. I.; Ocampo, A.; Owen, W. M.; Paetzold, M.; Page, B.; Pelletier, F.; Peterson, J.; Pinkine, N.; Piquette, M.; Porter, S. B.; Protopapa, S.; Redfern, J.; Reitsema, H. J.; Reuter, D. C.; Roberts, J. H.; Robbins, S. J.; Rogers, G.; Rose, D.; Runyon, K.; Ryschkewitsch, M. G.; Schenk, P.; Sepan, B.; Showalter, M. R.; Soluri, M.; Stanbridge, D.; Stryk, T.; Szalay, J. R.; Tapley, M.; Taylor, A.; Taylor, H.; Umurhan, O. M.; Verbiscer, A. J.; Versteeg, M. H.; Vincent, M.; Webbert, R.; Weidner, S.; Weigle, G. E.; White, O. L.; Whittenburg, K.; Williams, B. G.; Williams, K.; Williams, S.; Zangari, A. M.; Zirnstein, E.
2016-03-01
Observations made during the New Horizons flyby provide a detailed snapshot of the current state of Pluto's atmosphere. Whereas the lower atmosphere (at altitudes of less than 200 kilometers) is consistent with ground-based stellar occultations, the upper atmosphere is much colder and more compact than indicated by pre-encounter models. Molecular nitrogen (N2) dominates the atmosphere (at altitudes of less than 1800 kilometers or so), whereas methane (CH4), acetylene (C2H2), ethylene (C2H4), and ethane (C2H6) are abundant minor species and likely feed the production of an extensive haze that encompasses Pluto. The cold upper atmosphere shuts off the anticipated enhanced-Jeans, hydrodynamic-like escape of Pluto's atmosphere to space. It is unclear whether the current state of Pluto's atmosphere is representative of its average state - over seasonal or geologic time scales.
The atmosphere of Pluto as observed by New Horizons.
Gladstone, G Randall; Stern, S Alan; Ennico, Kimberly; Olkin, Catherine B; Weaver, Harold A; Young, Leslie A; Summers, Michael E; Strobel, Darrell F; Hinson, David P; Kammer, Joshua A; Parker, Alex H; Steffl, Andrew J; Linscott, Ivan R; Parker, Joel Wm; Cheng, Andrew F; Slater, David C; Versteeg, Maarten H; Greathouse, Thomas K; Retherford, Kurt D; Throop, Henry; Cunningham, Nathaniel J; Woods, William W; Singer, Kelsi N; Tsang, Constantine C C; Schindhelm, Eric; Lisse, Carey M; Wong, Michael L; Yung, Yuk L; Zhu, Xun; Curdt, Werner; Lavvas, Panayotis; Young, Eliot F; Tyler, G Leonard
2016-03-18
Observations made during the New Horizons flyby provide a detailed snapshot of the current state of Pluto's atmosphere. Whereas the lower atmosphere (at altitudes of less than 200 kilometers) is consistent with ground-based stellar occultations, the upper atmosphere is much colder and more compact than indicated by pre-encounter models. Molecular nitrogen (N2) dominates the atmosphere (at altitudes of less than 1800 kilometers or so), whereas methane (CH4), acetylene (C2H2), ethylene (C2H4), and ethane (C2H6) are abundant minor species and likely feed the production of an extensive haze that encompasses Pluto. The cold upper atmosphere shuts off the anticipated enhanced-Jeans, hydrodynamic-like escape of Pluto's atmosphere to space. It is unclear whether the current state of Pluto's atmosphere is representative of its average state--over seasonal or geologic time scales. PMID:26989258
Learn to Change: Teaching Toward a Shifting Health Care Horizon.
Hart, Laura C
2016-01-01
Changes in health care-including a growing emphasis on quality, outcomes, and lower costs-are transforming the delivery of care and creating a knowledge gap that continuing education must bridge. As clinicians and health leaders spend less time in hospital settings, educational activities are likely to extend their reach, for instance through online education distributed on laptops, tablets, or smartphones. Ezekiel J. Emanuel, MD, PhD, explored this shift in his 2016 keynote to the World Congress for Continuing Professional Development: "Learn to Change: Teaching Toward a Shifting Health Care Horizon." This article describes some of the main trends in health care that Dr. Emanuel foresees, focusing on the implications of the changing role of hospitals for innovation in continuing education. PMID:27584062
Attitude Determination by Using Horizon and Sun Sensors
NASA Technical Reports Server (NTRS)
Huang, Allen K. H.; French, Larry A.
1993-01-01
The Pointing and Alignment Workstation (PAWS) developed by Teledyne Brown Engineering (TBE) has successfully supported the first and second Atmospheric Laboratory for Applications and Science (ATLAS 1, 2) spacelab missions for NASA. The primary PAWS objective was to provide realtime pointing information to instruments whose line of-sight is dependent on Shuttle attitude and to study/quantify the causes and effects of Shuttle and payload pointing errors. In addition to Shuttle IMU attitude information, PAWS used atmospheric science sensors data to determine the spacecraft attitude. PAWS successfully achieved these goals by acquiring and processing data during the ATLAS 1, 2 mission. This paper presents the attitude determination algorithm real time processing, and results of post mission analysis. The findings of this study include the quality of the horizon sensor and IMU measurements as well as accuracy of attitude processor algorithm.
Shoreline oiling from the Deepwater Horizon oil spill.
Nixon, Zachary; Zengel, Scott; Baker, Mary; Steinhoff, Marla; Fricano, Gail; Rouhani, Shahrokh; Michel, Jacqueline
2016-06-15
We build on previous work to construct a comprehensive database of shoreline oiling exposure from the Deepwater Horizon (DWH) spill by compiling field and remotely-sensed datasets to support oil exposure and injury quantification. We compiled a spatial database of shoreline segments with attributes summarizing habitat, oiling category and timeline. We present new simplified oil exposure classes for both beaches and coastal wetland habitats derived from this database integrating both intensity and persistence of oiling on the shoreline over time. We document oiling along 2113km out of 9545km of surveyed shoreline, an increase of 19% from previously published estimates and representing the largest marine oil spill in history by length of shoreline oiled. These data may be used to generate maps and calculate summary statistics to assist in quantifying and understanding the scope, extent, and spatial distribution of shoreline oil exposure as a result of the DWH incident. PMID:27098990