Transit least-squares survey -- II. Discovery and validation of 17 new sub- to super-Earth-sized planets in multi-planet systems from K2

The extended Kepler mission (K2) has revealed more than 500 transiting planets in roughly 500,000 stellar light curves. All of these were found either with the box least-squares algorithm or by visual inspection. Here we use our new transit least-squares (TLS) algorithm to search for additional planets around all K2 stars that are currently known to host at least one planet. We discover and statistically validate 17 new planets with radii ranging from about 0.7 Earth radii to roughly 2.2 Earth radii and a median radius of 1.18 Earth radii. EPIC201497682.03, with a radius of 0.692 (-0.048, +0.059) Earth radii, is the second smallest planet ever discovered with K2. The transit signatures of these 17 planets are typically 200 ppm deep (ranging from 100 ppm to 2000 ppm), and their orbital periods extend from about 0.7 d to 34 d with a median value of about 4 d. Fourteen of these 17 systems only had one known planet before, and they now join the growing number of multi-planet systems. Most stars in our sample have subsolar masses and radii. The small planetary radii in our sample are a direct result of the higher signal detection efficiency that TLS has compared to box-fitting algorithms in the shallow-transit regime. Our findings help in populating the period-radius diagram with small planets. Our discovery rate of about 3.7 % within the group of previously known K2 systems suggests that TLS can find over 100 additional Earth-sized planets in the data of the Kepler primary mission.Comment: published in A&A, 12 pages, 6 colored Figures, 1 Table; minor textual corrections; Fig. 5 corrected for the distance scalin

Transit least-squares survey - I. Discovery and validation of an Earth-sized planet in the four-planet system K2-32 near the 1:2:5:7 resonance

We apply, for the first time, the Transit Least Squares (TLS) algorithm to search for new transiting exoplanets. TLS is a successor to the Box Least Squares (BLS) algorithm, which has served as a standard tool for the detection of periodic transits. In this proof-of-concept paper, we demonstrate how TLS finds small planets that have previously been missed. We showcase TLS' capabilities using the K2 EVEREST-detrended light curve of the star K2-32 (EPIC205071984) that was known to have three transiting planets. TLS detects these known Neptune-sized planets K2-32b, d, and c in an iterative search and finds an additional transit signal with a high signal detection efficiency (SDE_TLS) of 26.1 at a period of 4.34882 (-0.00075, +0.00069) d. We show that this signal remains detectable (SDE_TLS = 13.2) with TLS in the K2SFF light curve of K2-32, which includes a less optimal detrending of the systematic trends. The signal is below common detection thresholds, however, if searched with BLS in the K2SFF light curve (SDE_BLS = 8.9) as in previous searches. Markov Chain Monte Carlo sampling shows that the radius of this candidate is 1.01 (-0.09, +0.10) Earth radii. We analyze its phase-folded transit light curve using the vespa software and calculate a false positive probability FPP = 3.1e-3, formally validating K2-32e as a planet. Taking into account the multiplicity boost of the system, FPP < 3.1e-4. K2-32 now hosts at least four planets that are very close to a 1:2:5:7 mean motion resonance chain. The offset of the orbital periods of K2-32e and b from a 1:2 mean motion resonance is in very good agreement with the sample of transiting multi-planet systems from Kepler, lending further credence to the planetary nature of K2-32e. We expect that TLS can find many more transits of Earth-sized and smaller planets in the Kepler data that have hitherto remained undetected with BLS and similar algorithms.Comment: published in A&A, Vol. 625, id. A31 , 8 pages, 6 colored figure

Cultural Heritage as Environment: Area Conservation in Cairo\u27s Historic Zone

[abstract not provided]https://fount.aucegypt.edu/faculty_book_chapters/1943/thumbnail.jp

Revisiting the exomoon candidate signal around Kepler-1625b

Transit photometry of the exoplanet candidate Kepler-1625b has recently been interpreted to show hints of a moon. We aim to clarify whether the exomoon-like signal is really caused by a large object in orbit around Kepler-1625b. We explore several detrending procedures, i.e. polynomials and the Cosine Filtering with Autocorrelation Minimization (CoFiAM). We then supply a light curve simulator with the co-planar orbital dynamics of the system and fit the resulting planet-moon transit light curves to the Kepler data. We employ the Bayesian Information Criterion (BIC) to assess whether a single planet or a planet-moon system is a more likely interpretation of the light curve variations. We carry out a blind hare-and-hounds exercise using many noise realizations by injecting simulated transits into different out-of-transit parts of the original Kepler-1625 data: 100 sequences with 3 synthetic transits of a Kepler-1625b-like planet and 100 sequences with 3 synthetic transits of this planet with a Neptune-sized moon. The statistical significance and characteristics of the exomoon-like signal strongly depend on the detrending method, and the data chosen for detrending, and on the treatment of gaps in the light curve. Our injection-retrieval experiment shows evidence for moons in about 10% of those light curves that do not contain an injected moon. Strikingly, many of these false-positive moons resemble the exomoon candidate. We recover up to about half of the injected moons, depending on the detrending method, with radii and orbital distances broadly corresponding to the injected values. A $\Delta$BIC of -4.9 for the CoFiAM-based detrending indicates an exomoon around Kepler-1625b. This solution, however, is only one out of many and we find very different solutions depending on the details of the detrending method. It is worrying that the detrending is key to the interpretation of the data.Comment: 16 pages, 12 figures. Accepted for publication by A&

Cervantes and Islam: Attitudes Towards Islam and Islamic Culture in Don Quixote

This collective volume is the result of the Second Annual Conference on Cross-Cultural Encounters in the Mediterranean held at the American University in Cairo, 5-7 May, 1996. The contributors, David R. Blanks, John Victor Tolan, Nabil I. Matar, John Rodenbeck, Thabit Abdullah, E.M. Sartain, Omaima Abou-Bakr, and Nadia M. El-Cheik, take an interdisciplinary approach, drawing from sociology, anthropology, political science, history, and literature, in medieval their examination of past attitudes, in particular images of the \u27Other\u27 in medieval Europe, North Africa and the Middle East, in order to trace the origins of modern stereotypes. The essays are divided into three groups: Western images of Islamic culture, Muslim images of Europe, the Arabs and the Byzantines.https://fount.aucegypt.edu/faculty_book_chapters/1952/thumbnail.jp

Spatiotemporal Variation Of Avian Populations Within Geographically Isolated Freshwater Marshes

Metacommunity connectivity, i.e., multi-species dispersal events, is vital to metapopulation persistence in patchy landscapes. Assessments of metacommunity connectivity are not trivial. However, a relationship between trophic rank and the species-area relationship has been found in previous studies, allowing for the use of the predator species-area relationship to act as a surrogate measure of actual metacommunity connectivity of prey species in some systems. For this study, avian species were selected as they are generalist top predators within the study system. Predator species richness within geographically isolated freshwater marshes is influenced by a number of factors. I explore the relative roles of patch area, seasonality, hydroperiod, isolation, and vegetation structure on habitat use in the isolated freshwater marshes embedded within the dry prairie ecosystem of Central Florida. Predator species richness was surveyed in 50 sites for three seasons: fall 2005, winter 2005/06, and spring 2006 and the observed avian assemblage measures were subdivided into foraging guilds for analysis. Wading guild (e.g., egrets, herons, bitterns) species richness was correlated with hydroperiod and vegetation structural variables while perching guild (e.g., blackbirds, sparrows, meadowlarks) species richness was correlated with isolation, hydroperiod, and area annually. Overall predator and all guild species richness measures were also correlated with patch area for all seasons. These results suggest that while a complex mixture of patch area, hydroperiod and isolation influence habitat utilization that varies by season and at the community, guild and individual species level, the underlying predictors that define habitat use in wetlands annually includes hydroperiod, and is not exclusively patch area. Additionally, seasonal differences in predator species richness were found to be significant in some cases indicating that future avian population studies may benefit by sampling outside of the normally studied spring breeding season. Results of this study support the use of predator species richness as a suitable assay of metacommunity connectivity of prey species. Applications and implications of this approach toward future conservation efforts are discussed

Refactoring SASyLF Proofs

Refactoring is a common practice undertaken by software developers that is used to improve the quality of existing code. Originally done by hand, several automated refactorings have been introduced over the years, saving both time and effort expended by the developer. Proof engineering, on the other hand, is a more recent concept which has not advanced as quickly over the years, thus they do not have similar tools to be able to make similar changes automatically. Since proof assistants resemble programming languages in many regards, a similar practice may be applied.Thus, the main idea behind this thesis is introduced. The topic of refactoring is discussed, and how it can be applied to proof assistants as well as for programming languages. The framework of the proof assistant SASyLF is also introduced, including a description of its different components and its syntax. Additionally, some related work regarding proof refactoring is mentioned

Detection of exomoons in simulated light curves with a regularized convolutional neural network

Many moons have been detected around planets in our Solar System, but none has been detected unambiguously around any of the confirmed extrasolar planets. We test the feasibility of a supervised convolutional neural network to classify photometric transit light curves of planet-host stars and identify exomoon transits, while avoiding false positives caused by stellar variability or instrumental noise. Convolutional neural networks are known to have contributed to improving the accuracy of classification tasks. The network optimization is typically performed without studying the effect of noise on the training process. Here we design and optimize a 1D convolutional neural network to classify photometric transit light curves. We regularize the network by the total variation loss in order to remove unwanted variations in the data features. Using numerical experiments, we demonstrate the benefits of our network, which produces results comparable to or better than the standard network solutions. Most importantly, our network clearly outperforms a classical method used in exoplanet science to identify moon-like signals. Thus the proposed network is a promising approach for analyzing real transit light curves in the future

An Intersectional Examination of the Portrayal of Native American Women in Wisconsin Museum Exhibits

This project examines how White curators at four museums in Wisconsin portray Native American women based on a number of institutional and individual curatorial choices. Intersectional Theory is used to explore how museums and museum professionals navigate questions of representation of a traditionally marginalized group. It places specific emphasis on the relationship between Community Curation and Intersectional Theory and explores whether or not the involvement of Native groups noticeably impacts representation of Native American women. The study examines the exhibits of four museums: The Abel Public Museum, The New Canton College of Anthropology, The Pineville Public Museum, and The Wisconsin Museum of Natural History. These institutions vary in size, scope, audience, and curatorial strategies. However, they all have exhibits that depict Native Americans. Museum professionals from each institution were also interviewed to better understand how individual embodiments of particular Intersections of identity do or do not impact curatorial philosophies. In addition, the questions of bias, authority, and perspective are also evaluated in conjunction with critical approaches to museology. Finally, it explores some of the ways in which these structures uphold existing frameworks of colonialism and White supremacy and how Intersectional museum exhibits can be developed to combat these paradigms and ensure more diverse and accurate representation