On Partial Coherence and the Concept of 'Effective Source' as Used in Instrumental Optics

1963 ◽  
Vol 10 (2) ◽  
pp. 179-186 ◽  
Author(s):  
S.C. Som
Keyword(s):  
Partial Coherence ◽  
Effective Source

Interference Experiments with a Field Emission Source

1970 ◽  
Vol 28 ◽  
pp. 534-535
Author(s):  
A. V. Crewe ◽  
J. Saxon
Keyword(s):  
Field Emission ◽  
Spherical Aberration ◽  
Electron Gun ◽  
Partial Coherence ◽  
Vacuum System ◽  
High Brightness ◽  
Small Spot ◽  
Tungsten Tip ◽  
Effective Source ◽  
Better Than

Field emission from a tungsten tip provides a source with very high brightness and high partial coherence. An electron gun of low spherical aberration is used to focus the electrons from the tip to a small spot about 100 Å in diameter. Since the voltages applied to the tip and gun are stable to better than 5 ppm, the temporal coherence is limited by the energy spread of the source, about 200 mv.Using the focused spot a few centimeters below the gun as an effective source, a metalized quartz fiber about 2 μ in diameter is positioned a few centimeters below the source, as shown in Fig. 1. Two cylindrica11y symmetric magnetic lenses are used to magnify the resulting Fresnel diffraction pattern. The image is produced on a fluorescent coating deposited on the vacuum side of a fiber optic window. The image is recorded directly on film placed against the window outside the vacuum system.

scholarly journals Partial coherence and frustration in self‐organizing spherical grids

Hippocampus ◽  
2020 ◽  
Vol 30 (4) ◽  
pp. 302-313 ◽  
Author(s):  
Federico Stella ◽  
Eugenio Urdapilleta ◽  
Yifan Luo ◽  
Alessandro Treves
Keyword(s):  
Partial Coherence ◽  
Self Organizing

Lr80: A new and widely effective source of leaf rust resistance of wheat for enhancing diversity of resistance among modern cultivars

2021 ◽  
Author(s):  
Subodh Kumar ◽  
Subhash C. Bhardwaj ◽  
Om P. Gangwar ◽  
Akanksha Sharma ◽  
Naeela Qureshi ◽  
...  
Keyword(s):  
Leaf Rust ◽  
Rust Resistance ◽  
Leaf Rust Resistance ◽  
Effective Source

scholarly journals Capitalising on faith? An intergenerational study of social and religious capital among Baby Boomers and Millennials in Britain

2021 ◽  
Vol 69 (4) ◽  
pp. 862-880
Author(s):  
Stuart Fox ◽  
Esther Muddiman ◽  
Jennifer Hampton ◽  
Ekaterina Kolpinskaya ◽  
Ceryn Evans
Keyword(s):  
Social Capital ◽  
Baby Boomers ◽  
Social Institutions ◽  
Economic Security ◽  
Religious Capital ◽  
Intergenerational Study ◽  
The Uk ◽  
Active Generation ◽  
Effective Source

Intergenerational inequalities in economic security, health and political participation are frequently associated with inequalities in access to social capital. Millennials (those born after 1982) are often regarded as the least civically active generation, suggesting that they have less access to social capital, compared to other generations. Numerous studies have linked the decline of religion with falling social capital, as younger generations are deprived of a valuable source of social interaction; others, however, have claimed the link between the two is spurious because Millennials have developed different ways of interacting with social institutions and each other. Despite various studies exploring links between forms of religious and social capital, the role of religious decline in contributing to the intergenerational inequalities of today remains unclear. This study examines how religious capital is related to social capital for Baby Boomers and Millennials in the UK. Our analysis shows that while lower levels of religious capital are contributing to lower levels of social capital among Millennials, religious activity is also a more effective source of social capital for Millennials than their elders. We discuss possible interpretations of our data, including exploring whether greater religious engagement among Millennials may protect against intergenerational inequality and conflict.

scholarly journals Use of an Alignment-Free Method for the Geographical Discrimination of GTPVs Based on the GPCR Sequences

2021 ◽  
Vol 9 (4) ◽  
pp. 855
Author(s):  
Tesfaye Rufael Chibssa ◽  
Yang Liu ◽  
Melaku Sombo ◽  
Jacqueline Kasiiti Lichoti ◽  
Janchivdorj Erdenebaatar ◽  
...  
Keyword(s):  
Lumpy Skin Disease ◽  
Alignment Free ◽  
Central Asian ◽  
Source Tracing ◽  
Geographical Regions ◽  
Gpcr Gene ◽  
Geographical Discrimination ◽  
Sequence Profiles ◽  
G Protein Coupled ◽  
Effective Source

Goatpox virus (GTPV) belongs to the genus Capripoxvirus, together with sheeppox virus (SPPV) and lumpy skin disease virus (LSDV). GTPV primarily affects sheep, goats and some wild ruminants. Although GTPV is only present in Africa and Asia, the recent spread of LSDV in Europe and Asia shows capripoxviruses could escape their traditional geographical regions to cause severe outbreaks in new areas. Therefore, it is crucial to develop effective source tracing of capripoxvirus infections. Earlier, conventional phylogenetic methods, based on limited samples, identified three different nucleotide sequence profiles in the G-protein-coupled chemokine receptor (GPCR) gene of GTPVs. However, this method did not differentiate GTPV strains by their geographical origins. We have sequenced the GPCR gene of additional GTPVs and analyzed them with publicly available sequences, using conventional alignment-based methods and an alignment-free approach exploiting k-mer frequencies. Using the alignment-free method, we can now classify GTPVs based on their geographical origin: African GTPVs and Asian GTPVs, which further split into Western and Central Asian (WCA) GTPVs and Eastern and Southern Asian (ESA) GTPVs. This approach will help determine the source of introduction in GTPV emergence in disease-free regions and detect the importation of additional strains in disease-endemic areas.

Image Formation from Frozen Hydrated Samples in an Energy-Filter-Microscope

1997 ◽  
Vol 3 (S2) ◽  
pp. 1081-1082
Author(s):  
I. Angert ◽  
W. Jahn ◽  
K.C. Holmes ◽  
R.R. Schröder
Keyword(s):  
Biological Sample ◽  
Phase Contrast ◽  
Contrast Ratio ◽  
Partial Coherence ◽  
Atomic Resolution ◽  
Phase Approximation ◽  
Zero Energy ◽  
Contrast Transfer Function ◽  
Weak Phase ◽  
Definition Of

Understanding the contrast formation mechanism in the EM is one of the prerequisites for artefact-free reconstruction of biological structures from images. We found that the normally used correction of contrast formation applied to zero energy loss filtered images corrupted spatial resolution. Therefore the contribution of contrast formed by inelastic electrons was reconsidered, including partial coherence of inelastically scattered electrons and lens aberrations of the microscope. Based on this, a complete description of the zero-loss contrast transfer function (CTF) is now possible.We used tobacco mosaic virus (TMV), a biological sample known at atomic resolution, for definition of optimum CTF-parameters to reconstruct defocus series from an EFTEM LEO 912. CTF theory as known so far describes image contrast in the weak phase approximation as a linear sum of amplitude and phase contrast. The contribution of amplitude contrast (ratio of amplitude to phase contrast A/P) was determined to be between 7% and 5 % for unfiltered images and 12-14 % for zero-loss filtered images. However, in a filter microscope we remove electrons from the image, so we expect a higher amplitude contrast than in non-filtered images.

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