scholarly journals Discrimination of Bird and Insect Radar Echoes in Clear Air Using High-Resolution Radars

2007 ◽  
Vol 24 (7) ◽  
pp. 1215-1230 ◽  
Author(s):  
William J. Martin ◽  
Alan Shapiro
Keyword(s):  
High Resolution ◽  
Cross Section ◽  
Radar Meteorology ◽  
W Band ◽  
Radar Echoes ◽  
History Of ◽  
Entire History ◽  
Using Data ◽  
Wind Profiles ◽  
Bird Migrations

Abstract The source of clear-air reflectivity from operational and research meteorological radars has been a subject of much debate and study over the entire history of radar meteorology. Recent studies have suggested that bird migrations routinely contaminate wind profiles obtained at night, while historical studies have suggested insects as the main source of such nocturnal clear-air echoes. This study analyzes two cases of nocturnal clear-air return using data from operational Weather Surveillance Radar-1988 Doppler (WSR-88D) and X- and W-band research radars. The research radars have sufficient resolution to resolve the echo as point targets in some cases. By examining the radar cross section of the resolved point targets, and by determining the target density, it is found for both cases of nocturnal clear-air echoes that the targets are almost certainly insects. The analysis of the dependence of the echo strength on radar wavelength also supports this conclusion.

scholarly journals Digital games as a platform for understanding skill acquisition from novice to expert

2021 ◽  
Author(s):  
Tom Stafford ◽  
Nemanja Vaci
Keyword(s):  
Skill Acquisition ◽  
Cognitive Theory ◽  
Skill Development ◽  
Digital Games ◽  
Digital Environments ◽  
History Of ◽  
Practice Style ◽  
Entire History ◽  
Using Data ◽  
The Individual

Gamers invest many hours exploring digital environments in which simple rules can generate a complex space of action, response and interaction with other players. As well as being an industry with greater revenue than the global music and film industries combined, gaming is also a domain of profound skill development. Players' digital traces create an opportunity to understand the development of expertise from novice to professional-levels of skill, across the entire history of their practice, exploring how individual differences, practice style and other factors interact to enhance or impede skill acquisition. We review existing research into skill development using data from digital games and show how game data has been used to confirm, challenge and extend existing claims about the psychology of expertise. We show that game data allows novel analyses and offer recommendations for the future of research into learning using games. We argue that existing work, while exciting, has yet to take advantage of the potential of game data for understanding skill acquisition, and that to fully do so will require computational accounts of complete game performance, at the level of the individual, tied to a cognitive theory of skill and backed by experimental rather than observational studies.

Take Your Time? How Activity Timing Affects Organizational Learning and Performance Outcomes

2021 ◽  
Author(s):  
Vinit Desai ◽  
Peter Madsen
Keyword(s):  
Organizational Learning ◽  
Learning Theory ◽  
Theoretical Perspective ◽  
Performance Outcomes ◽  
Organizational Learning Theory ◽  
History Of ◽  
Entire History ◽  
And Performance ◽  
Using Data ◽  
Open Question

Organizational learning theory has long examined how organizations learn to perform better as they accumulate experience. Although experience accumulation is inherently related to the timing of the repeated activities carried out by an organization, the direct relationship between activity timing and organizational learning has not been examined explicitly in the literature and remains an open question. Organizational learning theory contains two competing perspectives on how timing should impact learning—one suggesting that iterating faster is better for learning and one suggesting that taking more time between iterations is more helpful. Here, we reconcile these perspectives and develop a theory about the boundary conditions between them, arguing that, in general, iterating more rapidly enhances learning but that iterations of novel or complex activities, or ones following recent failure, benefit from a slower pace. We conduct tests of this theoretical perspective using data from the entire history of the orbital satellite launch industry from 1957–2017, and we find broad support for our theory and hypotheses.

HRTEM simulation of interfacial structure in amorphous multilayers

1989 ◽  
Vol 47 ◽  
pp. 466-467
Author(s):  
Margaret L. Sattler ◽  
Michael A. O'Keefe
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Cross Section ◽  
High Resolution Electron Microscopy ◽  
Interfacial Structure ◽  
Multilayer Sample ◽  
Resolution Electron ◽  
Multilayered Materials ◽  
Simulated Images

Multilayered materials have been fabricated with such high perfection that individual layers having two atoms deep are possible. Characterization of the interfaces between these multilayers is achieved by high resolution electron microscopy and Figure 1a shows the cross-section of one type of multilayer. The production of such an image with atomically smooth interfaces depends upon certain factors which are not always reliable. For example, diffusion at the interface may produce complex interlayers which are important to the properties of the multilayers but which are difficult to observe. Similarly, anomalous conditions of imaging or of fabrication may occur which produce images having similar traits as the diffusion case above, e.g., imaging on a tilted/bent multilayer sample (Figure 1b) or deposition upon an unaligned substrate (Figure 1c). It is the purpose of this study to simulate the image of the perfect multilayer interface and to compare with simulated images having these anomalies.

Cross Section Analysis of Cu Filled TSVs Based on High Throughput Plasma-FIB Milling

2012 ◽  
Author(s):  
Frank Altmann ◽  
Jens Beyersdorfer ◽  
Jan Schischka ◽  
Michael Krause ◽  
German Franz ◽  
...  
Keyword(s):  
High Resolution ◽  
Cross Section ◽  
High Throughput ◽  
Cross Sections ◽  
Electron Backscatter Diffraction ◽  
Grain Structure ◽  
Electron Backscatter ◽  
Section Surface ◽  
Backscatter Diffraction ◽  
Section Analysis

Abstract In this paper the new Vion™ Plasma-FIB system, developed by FEI, is evaluated for cross sectioning of Cu filled Through Silicon Via (TSV) interconnects. The aim of the study presented in this paper is to evaluate and optimise different Plasma-FIB (P-FIB) milling strategies in terms of performance and cross section surface quality. The sufficient preservation of microstructures within cross sections is crucial for subsequent Electron Backscatter Diffraction (EBSD) grain structure analyses and a high resolution interface characterisation by TEM.

Organization of restrictive quarantine measures to prevent especially dangerous infections

2020 ◽  
pp. 6-11
Author(s):  
Petr Ilyin
Keyword(s):  
Infectious Diseases ◽  
Clinical Symptoms ◽  
International Health ◽  
World Health ◽  
The World ◽  
History Of ◽  
Entire History ◽  
Health Organization ◽  
Former Ussr ◽  
Health Regulations

Especially dangerous infections (EDIs) belong to the conditionally labelled group of infectious diseases that pose an exceptional epidemic threat. They are highly contagious, rapidly spreading and capable of affecting wide sections of the population in the shortest possible time, they are characterized by the severity of clinical symptoms and high mortality rates. At the present stage, the term "especially dangerous infections" is used only in the territory of the countries of the former USSR, all over the world this concept is defined as "infectious diseases that pose an extreme threat to public health on an international scale." Over the entire history of human development, more people have died as a result of epidemics and pandemics than in all wars combined. The list of especially dangerous infections and measures to prevent their spread were fixed in the International Health Regulations (IHR), adopted at the 22nd session of the WHO's World Health Assembly on July 26, 1969. In 1970, at the 23rd session of the WHO's Assembly, typhus and relapsing fever were excluded from the list of quarantine infections. As amended in 1981, the list included only three diseases represented by plague, cholera and anthrax. However, now annual additions of new infections endemic to different parts of the earth to this list take place. To date, the World Health Organization (WHO) has already included more than 100 diseases in the list of especially dangerous infections.

The Paving Stone Theory of World Tectonics

2018 ◽  
Author(s):  
Roy Livermore
Keyword(s):  
Indian Ocean ◽  
Plate Tectonics ◽  
Earth Science ◽  
Transform Faults ◽  
Plate Motions ◽  
Euler’S Theorem ◽  
History Of ◽  
New Ideas ◽  
Entire History ◽  
The Indian Ocean

Tuzo Wilson introduces the concept of transform faults, which has the effect of transforming Earth Science forever. Resistance to the new ideas is finally overcome in the late 1960s, as the theory of moving plates is established. Two scientists play a major role in quantifying the embryonic theory that is eventually dubbed ‘plate tectonics’. Dan McKenzie applies Euler’s theorem, used previously by Teddy Bullard to reconstruct the continents around the Atlantic, to the problem of plate rotations on a sphere and uses it to unravel the entire history of the Indian Ocean. Jason Morgan also wraps plate tectonics around a sphere. Tuzo Wilson introduces the idea of a fixed hotspot beneath Hawaii, an idea taken up by Jason Morgan to create an absolute reference frame for plate motions.

scholarly journals Overcoming barriers to the registration of new plant varieties under the DUS system

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Chin Jian Yang ◽  
Joanne Russell ◽  
Luke Ramsay ◽  
William Thomas ◽  
Wayne Powell ◽  
...  
Keyword(s):  
Current System ◽  
Registration System ◽  
Crop Varieties ◽  
Property System ◽  
Dus Testing ◽  
History Of ◽  
New Varieties ◽  
Entire History ◽  
Combinatorial Space ◽  
New Crop

AbstractDistinctness, Uniformity and Stability (DUS) is an intellectual property system introduced in 1961 by the International Union for the Protection of New Varieties of Plants (UPOV) for safeguarding the investment and rewarding innovation in developing new plant varieties. Despite the rapid advancement in our understanding of crop biology over the past 60 years, the DUS system has changed little and is still largely dependent upon a set of morphological traits for testing candidate varieties. As the demand for more plant varieties increases, the barriers to registration of new varieties become more acute and thus require urgent review to the system. To highlight the challenges and remedies in the current system, we evaluated a comprehensive panel of 805 UK barley varieties that span the entire history of DUS testing. Our findings reveal the system deficiencies such as inconsistencies in DUS traits across environments, limitations in DUS trait combinatorial space, and inadequacies in currently available DUS markers. We advocate the concept of genomic DUS and provide evidence for a shift towards a robust genomics-enabled registration system for new crop varieties.

scholarly journals Modification to the Hawking temperature of a dynamical black hole by a flow-induced supertranslation

2020 ◽  
Vol 2020 (12) ◽  
Author(s):  
Hsu-Wen Chiang ◽  
Yu-Hsien Kung ◽  
Pisin Chen
Keyword(s):  
Black Hole ◽  
Coordinate Transformation ◽  
Information Loss ◽  
Hawking Temperature ◽  
Asymptotic Region ◽  
Unruh Effect ◽  
Anisotropic Flow ◽  
Information Loss Paradox ◽  
History Of ◽  
Entire History

Abstract One interesting proposal to solve the black hole information loss paradox without modifying either general relativity or quantum field theory, is the soft hair, a diffeomorphism charge that records the anisotropic radiation in the asymptotic region. This proposal, however, has been challenged, given that away from the source the soft hair behaves as a coordinate transformation that forms an Abelian group, thus unable to store any information. To maintain the spirit of the soft hair but circumvent these obstacles, we consider Hawking radiation as a probe sensitive to the entire history of the black hole evaporation, where the soft hairs on the horizon are induced by the absorption of a null anisotropic flow, generalizing the shock wave considered in [1, 2]. To do so we introduce two different time-dependent extensions of the diffeomorphism associated with the soft hair, where one is the backreaction of the anisotropic null flow, and the other is a coordinate transformation that produces the Unruh effect and a Doppler shift to the Hawking spectrum. Together, they form an exact BMS charge generator on the entire manifold that allows the nonperturbative analysis of the black hole horizon, whose surface gravity, i.e. the Hawking temperature, is found to be modified. The modification depends on an exponential average of the anisotropy of the null flow with a decay rate of 4M, suggesting the emergence of a new 2-D degree of freedom on the horizon, which could be a way out of the information loss paradox.

scholarly journals Photoionization Cross-Sections of Carbon-Like N+ Near the K-Edge (390–440 eV)

Atoms ◽  
2021 ◽  
Vol 9 (2) ◽  
pp. 27
Author(s):  
Jean-Paul Mosnier ◽  
Eugene T. Kennedy ◽  
Jean-Marc Bizau ◽  
Denis Cubaynes ◽  
Ségolène Guilbaud ◽  
...  
Keyword(s):  
High Resolution ◽  
Cross Section ◽  
Cross Sections ◽  
Experimental Studies ◽  
Photoionization Cross Section ◽  
Theoretical Work ◽  
Rydberg Series ◽  
R Matrix ◽  
Resonance Strengths ◽  
Nitrogen Ion

High-resolution K-shell photoionization cross-sections for the C-like atomic nitrogen ion (N+) are reported in the 398 eV (31.15 Å) to 450 eV (27.55 Å) energy (wavelength) range. The results were obtained from absolute ion-yield measurements using the SOLEIL synchrotron radiation facility for spectral bandpasses of 65 meV or 250 meV. In the photon energy region 398–403 eV, 1s⟶2p autoionizing resonance states dominated the cross section spectrum. Analyses of the experimental profiles yielded resonance strengths and Auger widths. In the 415–440 eV photon region 1s⟶(1s2s22p2 4P)np and 1s⟶(1s2s22p2 2P)np resonances forming well-developed Rydberg series up n=7 and n=8 , respectively, were identified in both the single and double ionization spectra. Theoretical photoionization cross-section calculations, performed using the R-matrix plus pseudo-states (RMPS) method and the multiconfiguration Dirac-Fock (MCDF) approach were bench marked against these high-resolution experimental results. Comparison of the state-of-the-art theoretical work with the experimental studies allowed the identification of new resonance features. Resonance strengths, energies and Auger widths (where available) are compared quantitatively with the theoretical values. Contributions from excited metastable states of the N+ ions were carefully considered throughout.

scholarly journals Extensive introgression and mosaic genomes of Mediterranean endemic lizards

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Weizhao Yang ◽  
Nathalie Feiner ◽  
Catarina Pinho ◽  
Geoffrey M. While ◽  
Antigoni Kaliontzopoulou ◽  
...  
Keyword(s):  
Evolutionary History ◽  
Mediterranean Islands ◽  
The Past ◽  
Island Endemics ◽  
Extant Species ◽  
Mediterranean Island ◽  
History Of ◽  
Entire History ◽  
The Mediterranean ◽  
The Mediterranean Basin

AbstractThe Mediterranean basin is a hotspot of biodiversity, fuelled by climatic oscillation and geological change over the past 20 million years. Wall lizards of the genus Podarcis are among the most abundant, diverse, and conspicuous Mediterranean fauna. Here, we unravel the remarkably entangled evolutionary history of wall lizards by sequencing genomes of 34 major lineages covering 26 species. We demonstrate an early (>11 MYA) separation into two clades centred on the Iberian and Balkan Peninsulas, and two clades of Mediterranean island endemics. Diversification within these clades was pronounced between 6.5–4.0 MYA, a period spanning the Messinian Salinity Crisis, during which the Mediterranean Sea nearly dried up before rapidly refilling. However, genetic exchange between lineages has been a pervasive feature throughout the entire history of wall lizards. This has resulted in a highly reticulated pattern of evolution across the group, characterised by mosaic genomes with major contributions from two or more parental taxa. These hybrid lineages gave rise to several of the extant species that are endemic to Mediterranean islands. The mosaic genomes of island endemics may have promoted their extraordinary adaptability and striking diversity in body size, shape and colouration, which have puzzled biologists for centuries.

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