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1. Analysis of signal-to-noise ratio of angle of polarization and degree of polarization

   https://doi.org/10.1364/OSAC.422541  

   Chen, Yingkai; Zhu, Zhongmin; Liang, Zuodong; Iannucci, Leanne_E; Lake, Spencer_P; Gruev, Viktor (April 2021, OSA Continuum)

   Recent advancements in nanofabrication technology has led to commercialization of single-chip polarization and color-polarization imaging sensors in the visible spectrum. Novel applications have arisen with the emergence of these sensors leading to questions about noise in the reconstructed polarization images. In this paper, we provide theoretical analysis for the input and output referred noise for the angle and degree of linear polarization information. We validated our theoretical model with experimental data collected from a division of focal plane polarization sensor. Our data indicates that the noise in the angle of polarization images depends on both incident light intensity and degree of linear polarization and is independent of the incident angle of polarization. However, noise in degree of linear polarization images depends on all three parameters: incident light intensity, angle and degree of linear polarization. This theoretical model can help guide the development of imaging setups to record optimal polarization information. 

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2. Analysis of the Alignment of Non-Random Patterns of Spin Directions in Populations of Spiral Galaxies

   https://doi.org/10.3390/particles4010002  

   Shamir, Lior (March 2021, Particles)

   null (Ed.)

   Observations of non-random distribution of galaxies with opposite spin directions have recently attracted considerable attention. Here, a method for identifying cosine-dependence in a dataset of galaxies annotated by their spin directions is described in the light of different aspects that can impact the statistical analysis of the data. These aspects include the presence of duplicate objects in a dataset, errors in the galaxy annotation process, and non-random distribution of the asymmetry that does not necessarily form a dipole or quadrupole axes. The results show that duplicate objects in the dataset can artificially increase the likelihood of cosine dependence detected in the data, but a very high number of duplicate objects is required to lead to a false detection of an axis. Inaccuracy in galaxy annotations has relatively minor impact on the identification of cosine dependence when the error is randomly distributed between clockwise and counterclockwise galaxies. However, when the error is not random, even a small bias of 1% leads to a statistically significant cosine dependence that peaks at the celestial pole. Experiments with artificial datasets in which the distribution was not random showed strong cosine dependence even when the data did not form a full dipole axis alignment. The analysis when using the unmodified data shows asymmetry profile similar to the profile shown in multiple previous studies using several different telescopes. 

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3. Observation of the effect of gravity on the motion of antimatter

   https://doi.org/10.1038/s41586-023-06527-1  

   Anderson, E. K.; Baker, C. J.; Bertsche, W.; Bhatt, N. M.; Bonomi, G.; Capra, A.; Carli, I.; Cesar, C. L.; Charlton, M.; Christensen, A.; et al (September 2023, Nature)

   Abstract Einstein’s general theory of relativity from 1915¹remains the most successful description of gravitation. From the 1919 solar eclipse²to the observation of gravitational waves³, the theory has passed many crucial experimental tests. However, the evolving concepts of dark matter and dark energy illustrate that there is much to be learned about the gravitating content of the universe. Singularities in the general theory of relativity and the lack of a quantum theory of gravity suggest that our picture is incomplete. It is thus prudent to explore gravity in exotic physical systems. Antimatter was unknown to Einstein in 1915. Dirac’s theory⁴appeared in 1928; the positron was observed⁵in 1932. There has since been much speculation about gravity and antimatter. The theoretical consensus is that any laboratory mass must be attracted⁶by the Earth, although some authors have considered the cosmological consequences if antimatter should be repelled by matter^7–10. In the general theory of relativity, the weak equivalence principle (WEP) requires that all masses react identically to gravity, independent of their internal structure. Here we show that antihydrogen atoms, released from magnetic confinement in the ALPHA-g apparatus, behave in a way consistent with gravitational attraction to the Earth. Repulsive ‘antigravity’ is ruled out in this case. This experiment paves the way for precision studies of the magnitude of the gravitational acceleration between anti-atoms and the Earth to test the WEP. 

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4. Extensions of bundles of C*-algebras

   https://doi.org/10.1142/S0129055X21500252  

   Steeger, Jeremy; Feintzeig, Benjamin (January 2021, Reviews in Mathematical Physics)

   null (Ed.)

   Bundles of C*-algebras can be used to represent limits of physical theories whose algebraic structure depends on the value of a parameter. The primary example is the [Formula: see text] limit of the C*-algebras of physical quantities in quantum theories, represented in the framework of strict deformation quantization. In this paper, we understand such limiting procedures in terms of the extension of a bundle of C*-algebras to some limiting value of a parameter. We prove existence and uniqueness results for such extensions. Moreover, we show that such extensions are functorial for the C*-product, dynamical automorphisms, and the Lie bracket (in the [Formula: see text] case) on the fiber C*-algebras. 

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5. Sonification of Chemotactic Waves of Bacteria

   https://doi.org/10.21785/icad2023.8263  

   Braun, Rhea; Tfirn, Maxwell; Ford, Roseanne (June 2023, International Community for Auditory Display)

   Chemotaxis is the ability of certain microscopic organisms to sense and swim towards beneficial or away from detrimental chemicals in their surroundings. Identifying this behavior is important for understanding the relationships between species and their environments in the natural world. Predicting migration of an entire population from known characteristics of individual microorganisms is a key contribution, but can be a laborious process and requires watching and waiting for visual evidence of the process on a large population scale. Sonification offers a novel solution to this problem by allowing the observer to tap into our auditory sensory system to process information. In this project, we developed and assessed a proof-of-concept sonification tool as a high throughput, real-time screening tool for chemotaxis in populations of swimming bacteria. The tool operates by reporting the y-axis position of bacteria that appear in the microscope image as microsecond duration pitched notes, giving the user a sense of the average location of the population. In this paper, we present how it has been used as a chemotaxis assay and as a tool to locate traveling waves of bacteria as they pass through the field of view in order to capture data at specific timepoints, which is used to analyze individual swimming patterns of microorganisms within the wave. 

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