Additional Independent Source Research Articles

Immunization against complete subversion without random oracles

We seek constructions of general-purpose immunizers that take arbitrary cryptographic primitives, and transform them into ones that withstand a powerful “malicious but proud” adversary, who attempts to break security by possibly subverting the implementation of all algorithms (including the immunizer itself!), while trying not to be detected. This question is motivated by the recent evidence of cryptographic schemes being intentionally weakened, or designed together with hidden backdoors, e.g., with the scope of mass surveillance.Our main result is a subversion-secure immunizer in the plain model, that works for a fairly large class of deterministic primitives, i.e. cryptoschemes where a secret (but tamperable) random source is used to generate the keys and the public parameters, whereas all other algorithms are deterministic. The immunizer relies on an additional independent source of public randomness, which is used to sample a public seed.Assuming the public source is untamperable, and that the subversion of the algorithms is chosen independently of the seed, we can instantiate our immunizer from any one-way function. In case the subversion is allowed to depend on the seed, and the public source is still untamperable, we obtain an instantiation from collision-resistant hash functions. In the more challenging scenario where the public source is also tamperable, we additionally need to assume that the initial cryptographic primitive has sub-exponential security.Previous work in the area only obtained subversion-secure immunization for very restricted classes of primitives, often in weaker models of subversion and using random oracles.

Identification of Single Spectral Lines through Supervised Machine Learning in a Large HST Survey (WISP): A Pilot Study for Euclid and WFIRST

Future surveys focusing on understanding the nature of dark energy (e.g., Euclid and WFIRST) will cover large fractions of the extragalactic sky in near-IR slitless spectroscopy. These surveys will detect a large number of galaxies that will have only one emission line in the covered spectral range. In order to maximize the scientific return of these missions, it is imperative that single emission lines are correctly identified. Using a supervised machine-learning approach, we classified a sample of single emission lines extracted from the WFC3 IR Spectroscopic Parallel survey (WISP), one of the closest existing analogs to future slitless surveys. Our automatic software integrates a SED fitting strategy with additional independent sources of information. We calibrated it and tested it on a "gold" sample of securely identified objects with multiple lines detected. The algorithm correctly classifies real emission lines with an accuracy of 82.6%, whereas the accuracy of the SED fitting technique alone is low (~50%) due to the limited amount of photometric data available (<=6 bands). While not specifically designed for the Euclid and WFIRST surveys, the algorithm represents an important precursor of similar algorithms to be used in these future missions.

Stochastic Dominance under Independent Noise

Stochastic dominance is a crucial tool for the analysis of choice under risk. It is typically analyzed as a property of two gambles that are taken in isolation. We study how additional independent sources of risk (e.g. uninsurable labor risk, house price risk, etc.) can affect the ordering of gambles. We show that, perhaps surprisingly, background risk can be strong enough to render lotteries that are ranked by their expectation ranked in terms of first-order stochastic dominance. We extend our results to second order stochastic dominance, and show how they lead to a novel, and elementary, axiomatization of mean-variance preferences.

Country and industry factors in tests of Capital Asset Pricing Models for partially integrated emerging markets

Existing literature has produced broadly inconclusive evidence about the asset pricing model which best fits partially integrated markets. This paper examines whether industry and country factors are independent factors helping to determine returns in emerging stock markets, or are derived from the stocks’ risk-return characteristics. We link the country-industry decomposition framework to the local and the Global CAPM in a new and more direct way. The results show that country factors are additional independent sources of cross-sectional variation in stock returns before 1996 particularly under the Global CAPM. After 1996, the results suggest partial integration: industry and country factors are both additional independent determinants of cross-sectional variations in stock returns. .

OPTIMIZATION OF THE CONVERTER CHARACTERISTICS IN BRAKING TRANSITION MODES OF TRACTION ENGINE

Described conditions of converter optimization for DC engine braking modes. Braking minimizes the level of current ripple when using various methods of current regulation. Solving problems of efficient use of a DC traction engine and create safe modes of operation by ensuring optimal mode. The introduction of additional elements in the scheme allows to reduce the rate of attenuation of the current in the brake coils. A significant advantage of the proposed circuit modernization is the introduction of diodes in the circuit, which will allow the use of self-excitation of the electric motor for electrical braking. The proposed solution simplifies the technical implementation and reduces costs due to the lack of an additional independent power source for the brake coils. A significant factor in increasing the profitability of electric transport in general may be the replacement of an existing traction electric drive (TEP) with their more modern types. Simulation models have been developed to allow the study of electromechanical processes in a serial DC engine. Introduction to the circuit of a pulsed regulator diode, which shunts the excitation winding, reduces the rate of attenuation of the current in this winding. The proposed modernization of the circuit is to introduce into the circuit the diodes, an energy storage, which allows the use of brake modes for self-excitation of the motor and to avoid the use of additional independent sources of current.

Ignition of deflagration and detonation ahead of the flame due to radiative preheating of suspended micro particles

We study a flame propagating in the gaseous combustible mixture with suspended inert solid micro particles. The gaseous mixture is assumed to be transparent for thermal radiation emitted by the hot combustion products, while particles absorb and reemit the radiation. Thermal radiation heats the particles, which in turn transfer the heat to the surrounding unburned gaseous mixture by means of thermal heat transfer, so that the gas phase temperature lags that of the particles. We consider different scenarios depending on the spatial distribution of the particles, their size and the number density. In the case of uniform spatial distribution of the particles the radiation causes a modest increase of the temperature ahead of the flame and corresponding modest increase of the combustion velocity. In the case of non-uniform distribution of the particles (layered dust cloud), such that the particles number density is relatively small in the region just ahead of the flame front and increases in the distant regions ahead of the flame, the preheating caused by the thermal radiation may trigger additional independent source of ignition. Far ahead of the flame, where number density of particles increases forming a dense cloud of particles, the radiative preheating results in the formation of a temperature gradient with the maximum temperature sufficient for ignition. Depending on the steepness of the temperature gradient formed in the unburned mixture, either deflagration or detonation can be initiated via the Zel'dovich's gradient mechanism. The ignition and the resulting combustion regimes depend on the number density profile and, correspondingly, on the temperature profile (temperature gradient), which is formed in effect of radiation absorption and gas-dynamic expansion. The effect of radiation preheating as stronger as smaller is the normal flame velocity. The effect of radiation heat transfer in the case of coal dust flames propagating in layered particle-gas deposits cloud can result in the spread of combustion wave with velocity up to 1000 m/s and it is a plausible explanation of the origin of dust explosion in coal mines.

Influence of radiation absorption by microparticles on the flame velocity and combustion regimes

Thermal radiation of the hot combustion products usually does not influence noticeably the flame propagating through gaseous mixture. the situation is changed drastically in the presence even small concentration of particles, which absorb radiation, transfer the heat to the surrounding unburned gaseous mixture by means of heat conduction, so that the gas phase temperature in front of the advancing flame lags that of the particles. It is shown that radiative preheating of unreacted mixture ahead of the flame results in a modest increase of the advancing flame velocity for a highly reactive gaseous fuel, or to considerable increase of the flame velocity in the case of a slow reactive mixture. The effects of radiation preheating as stronger as smaller the normal flame velocity. The radiation heat transfer can become a dominant mechanism compared with molecular heat conduction, determining the structure and the speed of combustion wave in the case of a small enough velocity of the advancing flame. It is shown that in the case of non-uniform distribution of the particles, such that time of the radiation heating is longer so that the maximum temperature in the region of denser particles cloud ahead of the advancing flame is sufficient for ignition, the thermal radiation may trigger additional independent source of ignition. Depending on the steepness of the temperature gradient formed in the unburned mixture, either deflagration or detonation can be initiated via the Zeldovich's gradient mechanism. Ignition of different combustion regimes, depending on the radiation absorption length, is illustrated for the particle-laden hydrogen-oxygen flame.

SSR FINGERPRINTING OF BLACK RASPBERRY CULTIVARS SHOWS DISCREPANCIES IN IDENTIFICATION

Breeding progress in black raspberry (Rubus occidentalis L.) has been limited by a lack of genetic diversity in elite germplasm. Black raspberry cultivars are noted for showing very few differences, and seedlings for a lack of segregation for important traits. Genetic fingerprinting using microsatellite, or simple sequence repeat (SSR) markers, can reliably identify unique clones and evaluate diversity in black raspberry cultivars. Twenty-one black raspberry cultivars were sampled from the USDA-ARS National Clonal Germplasm Repository (NCGR) in Corvallis, Oregon. Black raspberry clones were also sampled from nurseries, grower’s fields, and other black raspberry breeding programs for comparison. These genotypes were compared using 18 polymorphic SSR primer pairs. The black raspberries 'Bristol,' 'Jewel,' and 'Mac Black' had consistent SSR fingerprints between sources. However, plants being sold as 'Black Hawk' and 'Cumberland' had the same fingerprint as 'Jewel'. Plants of 'Bristol', 'Cumberland', 'Munger', 'New Logan', 'Plum Farmer' and 'Shuttleworth' in the NCGR collection had identical fingerprints. Eleven unique SSR fingerprints were found among plants being grown or sold as ‘Munger’, though there was one predominant fingerprint for this cultivar. 'Allen' and 'John Robertson' were each represented by three different fingerprints from three different sources, and 'Earlysweet' and 'Jewel' had SSR alleles at multiple loci that cannot be explained by their reported pedigrees. While overall genetic diversity in black raspberry cultivars is low, discrepancies in the naming of clones appear to be widespread in commercial and research plantings. Future work in this area should focus on sampling additional independent sources of plant material and evaluating clones to determine the extent of performance differences. Further SSR development in black raspberry may be needed to fingerprint some unique clones.

An intercomparison of available soil moisture estimates from thermal infrared and passive microwave remote sensing and land surface modeling

[1] Remotely sensed soil moisture studies have mainly focused on retrievals using active and passive microwave (MW) sensors, which provide measurements that are directly related to soil moisture (SM). MW sensors have obvious advantages such as the ability to retrieve through nonprecipitating cloud cover which provides shorter repeat cycles. However, MW sensors offer coarse spatial resolution and suffer from reduced retrieval skill over moderate to dense vegetation. A unique avenue for filling these information gaps is to exploit the retrieval of SM from thermal infrared (TIR) observations, which can provide SM information under vegetation cover and at significantly higher resolutions than MW. Previously, an intercomparison of TIR-based and MW-based SM has not been investigated in the literature. Here a series of analyses are proposed to study relationships between SM products during a multiyear period (2003–2008) from a passive MW retrieval (AMSR-E), a TIR based model (ALEXI), and a land surface model (Noah) over the continental United States. The three analyses used in this study include (1) a spatial anomaly correlation analysis, (2) a temporal correlation analysis, and (3) a triple collocation error estimation technique. In general, the intercomparison shows that the TIR and MW methods provide complementary information about the current SM state. TIR can provide SM information over moderate to dense vegetation, a large information gap in current MW methods, while serving as an additional independent source of SM information over low to moderate vegetation. The complementary nature of SM information from MW and TIR sensors implies a potential for integration within an advanced SM data assimilation system.

Comparison of energetic ions in cusp and outer radiation belt

Recently, large diamagnetic cavities with a size of as large as 6 Re have been observed in the dayside high-altitude cusp regions. Associated with these cavities are charged particles with energies from 20 keV up to 10 MeV. Their seed population is a mixture of ionospheric and solar wind particles. The energetic ion intensity, charge composition, energy spectrum, and phase space density observed in the high-altitude dayside cusp have been compared with that measured in the outer radiation belt over an energy range of 1-200 keV/e for protons and He ++ ions and of 41-200 keV/e for O + ions. It is found that (1) the shape of ion energy spectra in the cusp is different from that in the outer radiation belt, (2) the ion phase space densities in the outer radiation belt are organized by magnetic moment, and (3) the ion phase space density of both He ++ and O + in the cusp are higher than that in the outer radiation belt at a given magnetic moment. These results suggest that (1) the measured cusp energetic ions cannot be explained by simple transport from an outer radiation belt (or ring current) source; rather, (2) a nonadiabatic energization process would be required to relate the cusp energetic ion population to the belt ion population, and (3) cusp energetic particles are potentially an additional independent source of the charged particles in the outer radiation belt.

Estimation of deforestation rates in Great Britain

Summary Estimates of national deforestation rates are required for reporting under the United Nations Framework Convention on Climate Change (UNFCCC) and the Kyoto Protocol. The most direct record of deforestation in Great Britain (GB) is provided by Forestry Commission (FC) unconditional felling licences, which give a value of ~500 ha a ‐1 for recent years. This probably represents a minimum, as unlicensed felling will also occur but to an unknown extent. The deforestation rate can be estimated indirectly by constructing a forest area budget, assuming deforestation is the residual term remaining after the observed change in forest area is subtracted from the recorded area of newly planted forest. Independent estimates of the total GB forest area can be obtained from the FC Woodland Census, the FC National Inventory of Woodland & Trees, and the Countryside Survey. An additional independent source of estimates of the total Scottish forest area is provided by the National Countryside Monitoring Scheme (NCMS). The observed increase in total area in these data does not differ significantly from the recorded planting rate, and a statistically significant deforestation rate was not detectable. An alternative approach is to use national survey schemes, in which repeated surveys of land use are made in a set of permanent plots. Deforestation rate can be calculated as the sum of transitions from all forest classes to all non-forest classes. Both the NCMS and the Countryside Survey can be used in this way. The NCMS survey can be scaled to give a GB deforestation rate of ~1000 ha a ‐1 , whilst the Countryside Survey gives a value of ~20000 ha a ‐1 . The NCMS value is thought to be more reliable, as the afforestation rate estimated in this way agrees closely with FC figures, whilst the Countryside Survey substantially overestimates afforestation. National mapping data from the Ordnance Survey (OS) can be used in a similar way and, as the whole country is covered by a rolling programme of surveys, sampling bias should be removed. These data show a similar temporal pattern to the felling licence data, but with considerably higher deforestation rates, with a mean of 4059 ha a ‐1 and a peak at over 7000 ha a ‐1 . However, these data suggest that there was substantial conversion of forest to agricultural land (62 per cent of the total deforested area). It seems unlikely that extensive unlicensed felling would have occurred for expanding agricultural land, when there has been little economic or policy incentives to do so, and we therefore suspect that these data may overestimate rural deforestation. The best estimate of the recent deforestation rate may be obtained by combining the data from the FC unconditional felling licences (accounting for conversions to rural uses) with the OS estimate of deforestation for non-rural uses which do not generally require a felling licence. This gives a value of 1375 ha a ‐1 .

Objective Identification of Echoes Due to Anomalous Propagation in Weather Radar Data

Abstract Serious contamination of weather radar data can occur in atmospheric conditions that cause anomalous propagation of the radar beam. Excessive downward refraction of the beam may be sufficient to cause ground returns (“anaprop”), which may be difficult to distinguish from rainfall echoes. At the U.K. Meteorological Office, an automatic scheme has been devised to combine several sources of evidence, by means of Bayesian statistics, to estimate the probability that an echo is caused by anaprop. Currently, the scheme uses hourly surface observations, Meteosat infrared images, a climatology of anaprop echoes, and detected lightning, but additional independent sources would be easy to add. Results from the automatic scheme have been compared with those from an interactive quality control procedure and show agreement of around 90% in the cases evaluated. Promising areas for extension and refinement of the scheme are suggested.

Lord's MAD Paradox and Jensen's Inequality

Abstract Lord (1983) showed that the mean absolute deviation (MAD) measure of dispersion does not always increase when an additional independent source of random variation is added. Jensen's inequality is used to find necessary and sufficient conditions for this paradoxical behavior. The conditions are unlikely to occur in practice.