bluuebunny/crossref_metadata_2025 huggingface dataset:
m6A-related lncRNA-based immune infiltration characteristic analysis and prognostic model for colonic adenocarcinoma
Authors: Wang Hao-lun , Ye Zhuo-miao , He Zi-yun , Huang Lu , Liu Zhi-hui
Published: February 2023

Background

Colonic adenocarcinoma (COAD) is a common gastrointestinal tract tumor, and its occurrence and progression are typically associated with genomic instability, tumor-suppressor gene and oncogene mutations, and tumor mutational load. N6-methyladenosine (m6A) modification of RNAs and long non-coding RNA (lncRNA) expression are important in tumorigenesis and progression. However, the regulatory roles of m6A‐associated lncRNAs in the tumor microenvironment, stratification of prognosis, and immunotherapy are unclear.

Methods

We screened 43 prognostic lncRNAs linked to m6A and performed consistent molecular typing of COAD using consensus clustering. The single-sample Gene Set Enrichment Analysis and ESTIMATE algorithms were used to assess the immune characteristics of different subgroups. Covariation between methylation-related prognostic lncRNAs was eliminated by least absolute shrinkage and selection operator Cox regression. A nomogram was created and evaluated by combining the methylation-related prognostic lncRNA model with other clinical factors. The relationship between the prognostic model grouping and microsatellite instability, immunophenotype score, and tumor mutation burden was validated using R scripts. Finally, we used a linkage map to filter sensitive medicines to suppress the expression of high-risk genes.

Three m6A-associated lncRNA modes were identified in 446 COAD specimens with different clinical endpoints and biological statuses. Risk scores were constructed based on the m6A-associated lncRNA signature genes. Patients with lower risk scores showed superior immunotherapy responses and clinical benefits compared to those with higher risk scores. Lower risk scores were also correlated with higher immunophenotype scores, tumor mutation burden, and mutation rates in significantly mutated genes (e.g., FAT4 and MUC16). Piperidolate, quinostatin, and mecamylamin were screened for their abilities to suppress the expression of high-risk genes in the model.

Conclusions

Quantitative assessment of m6A-associated lncRNAs in single tumors can enhance the understanding of tumor microenvironment profiles. The prognostic model constructed using m6A-associated lncRNAs may facilitate prognosis and immunotherapy stratification of patients with COAD; finally, three drugs with potential therapeutic value were screened based on the model.
Cervical catheter placement leads to improved rostral distribution of a radiolabeled 18F-baclofen analog in cynomolgus monkeys
Authors: Duclos Brian A. , Roegge Cindy , Dobson Howard , Haller Scott , Bodner Jeff , Pannem Sanjana , Gesaman Janelle , Nourmohammadi Amin
Published: February 2023

Background

Intrathecal (IT) catheter delivery of baclofen via continuous infusion using an implantable pump is an important means of treating patients with severe spasticity. We evaluated the impact of IT catheter tip placement (upper vs. lower) on brain and spine distribution of a radioactive tracer molecule.

Methods

Cynomolgus monkeys were implanted with an IT catheter, with the distal tip located at either C1 or T10 and attached to an implanted continuous infusion pump. A radioactive tracer molecule, an 18F-baclofen analog, and PET imaging were utilized to observe tracer distribution and quantitate levels of tracer in both the brain and spine according to catheter tip location.

Results

It was consistently determined that a high cervical (C1) catheter tip placement resulted in both more rapid distribution and higher concentrations of radiotracer in the brain and upper spine compared with lower thoracic (T10) during the first 6 hours of infusion.

Conclusions

These results indicate that delivery of 18F-baclofen by IT catheter results in repeatable proportional distribution within regions of the brain and spine. The data also suggest that the greatest exposure to the brain and cervical spinal cord occurs when the catheter tip is located at the first cervical vertebra.
Comparative assessment of coronary physiology using transthoracic pulsed-wave Doppler and myocardial contrast echocardiography in rats
Authors: Billig Sebastian , Hein Marc , Mechelinck Mare , Schumacher David , Roehl Anna B. , Fuchs Dieter , Kramann Rafael , Uhlig Moritz
Published: February 2023

Background

Coronary physiology assessment in rodents by ultrasound is an excellent noninvasive and easy to perform technique, including pulsed-wave Doppler (PWD) and myocardial contrast echocardiography (MCE). Both techniques and the corresponding calculated parameters were investigated in this study at rest as well as their response to pharmacologically induced stress.

Methods

Left ventricular myocardial function was assessed in eight anaesthetised rats using transthoracic echocardiography. Coronary physiology was assessed by both PWD of the left coronary artery and MCE using a bolus method. Measurements were performed at rest and under stimulation with adenosine and dobutamine. Effects of stimulation on the calculated parameters were evaluated and rated by effect size (η2).

Results

Changes could be demonstrated by selected parameters of PWD and MCE. The clearest effect in PWD was found for diastolic peak velocity (η2 = 0.58). It increased from 528 ± 110 mm/s (mean ± standard deviation) at rest to 839 ± 342 mm/s (p = 0.001) with adenosine and 1093 ± 302 mm/s with dobutamine (p = 0.001). The most distinct effect from MCE was found for the normalised wash-in rate (η2 = 0.58). It increased from 1.95 ± 0.35% at rest to 3.87 ± 0.85% with adenosine (p = 0.001) and 3.72 ± 1.03% with dobutamine (p = 0.001).

Conclusion

Induced changes in coronary physiology by adenosine and dobutamine could successfully be monitored using MCE and PWD in anaesthetised rats. Due to the low invasiveness of the measurements, this protocol could be used for longitudinal animal studies.
18F-FDG PET/CT in therapy response assessment: oligometastatic colorectal cancer
Authors: Nasr Ibrahim Mansour , Maksoud Bader Abdel , Rezk Mahmoud Ali , Badawy Ahmed , Almorsy Walid Ahmed , Ali Ismail Mohamed
Published: February 2023

Background

Colorectal cancer (CRC) is one of the most widespread cancers worldwide, leading to roughly half a million deaths yearly. The European Society for Medical Oncology defined oligometastatic CRC as a disease with few metastases affecting a small number of sites (5 or occasionally more metastases involving up to 3 sites). In addition to colonoscopy, magnetic resonance imaging (MRI), and digital rectal examination in patients with rectal cancer, response monitoring of CRC is commonly carried out by CT imaging. The use of PET for response monitoring has not been adapted into colorectal cancer guidelines until 2021. However, 18F-Fluorodeoxyglucose Positron Emission Tomography Computed Tomography (18F-FDG PET/CT) offers a higher efficiency for assessing treatment outcomes than traditional imaging. This study aims to explore the utility of 18F-FDG PET/CT imaging in the assessment of therapy response in patients with oligometastatic colorectal cancer (OMCRC).

Results

The study comprised 79 OMCRC patients (35 and 44 patients with synchronous and metachronous metastasis respectively). In synchronous disease patients 18F-FDG PET/CT scan showed significant reduction of mean size and standardized uptake value (SUV) of the primary site lesions and the mean SUV of lymph nodes (LNs) and lung metastases (P = 0.00, 0.00,0.00, and 0.002, respectively) while, metachronous disease patients had significant reduction in the mean size and SUV of LNs (1.8 ± 0.7 & 4.7 ± 1.3 versus 1.1 ± 1.0 & 2.9 ± 3.0, P = 0.001 & 0.00 respectively) and the mean SUV of peritoneal metastases (8.7 ± 4.7 versus 6.8 ± 2.4 P = 0.00). Partial metabolic response (PMR) and stable metabolic disease (SMD) were found in more than half of the patients (58.2%). Complete metabolic response (CMR) and Progressive metabolic disease (PMD), on the other hand, were achieved in 41.8% of patients [17 (21.5%) and 16 (20.3%) patients, respectively] with substantially higher CMR rate in metachronous disease than synchronous disease [14.0 (31.8%) versus 3.0 (8.5%) patients, P = 0.015)].

Conclusions

18F-FDG PET/CT can be added as a valuable imaging method for identifying responders and non-responders among OMCRC patients, as it optimizes the selection of patients with CRC for local therapy and has a significant impact on directing their therapy course. Oligometastatic colorectal cancer seems to be a controllable disease with hopeful therapy outcomes, particularly for those with metachronous metastases.
The value of blood and urine metabolomics in differential diagnosis of cholestasis in infants
Authors: Eshiaty Samah Abdelfatah , Abdelsattar Shimaa , Sweed Dina , Abdel-Aziz Samira A. , Elfert Ashraf , Elsaid Hala
Published: February 2023

Background

Early detection of biliary atresia (BA) is a great challenge providing the main useful way to improve its clinical consequence. Promising metabolomics provides an effective method for determining innovative biomarkers and biochemical ways for improving early diagnosis. This study aimed to determine the benefit of serum and urinary potential bile acid metabolites in the differentiation of BA from non-biliary atresia (non-BA) cases using tandem mass spectrometry (MS/MS). Fourteen bile acids metabolites were measured quantitively by MS/MS in serum and urine samples from 102 cholestatic infants and 102 control infants, in addition to the assay of the total serum bile acid enzymatically.

Results

After the diagnostic clinical and laboratory workflow, cholestatic infants were divided into BA (37 infants) and non-BA (65 infants) subgroups. Remarkably on analysis of serum individual bile acid concentrations, there were significant differences between cholestatic BA and non-BA regarding serum (glycocenodeoxycholic acid (GCDCA), taurochenodeoxycholic acid (TCDCA), taurocholic acid (TCA), and GCDCA/chenodeoxycholic acid (CDCA) ratio) (p < 0.001, for all), while there was no significant difference between the two groups regarding serum level of (cholic acid (CA), glycocholic (GCA), or TCDCA/CDCA ratio). There were no significant differences in either the urinary individual bile acids or urinary primary bile acids (conjugated or unconjugated) between BA and non-BA. Further principal component analysis (PCA) analysis was done and receiver operating characteristic (ROC) analysis was performed using score plots of the positive factors in the first two principal components PC1 (CA, GCA, GCDCA, TCA, TCDCA) and PC2 (CA, CDCA, lithocholic (LCA), ursodeoxycholic acid (UDCA)) for establishing the differences between the two diseased groups and revealed that the area under the curve (AUC) for PC1 was (0.770) higher than AUC for PC2 (0.583) indicating that the positive components of PC1 may be potential biomarkers for differentiation between the two cholestatic groups.

Conclusions

Metabolomics of serum bile acid levels using tandem mass spectrometry might change the paradigm differentiating BA from non-BA saving patients from unnecessary invasive procedures.
Αξιολόγηση της ικανότητας εξαγωγής συμπεράσματος σε παιδιά με Αναπτυξιακή Γλωσσική Διαταραχή: Πιλοτική μελέτη και προκαταρκτικά συμπεράσματα
Authors: Κεχαγιά Θεοδώρα , Τάλλη Ιωάννα
Published: February 2023

Στόχος της παρούσας μελέτης είναι να εξετάσει εάν τα παιδιά με Αναπτυξιακή Γλωσσική Διαταραχή (ΑΓΔ) έχουν δυσκολίες στην εξαγωγή συμπεράσματος. Στη μελέτη συμμετείχαν τριάντα παιδιά ηλικίας 5.1 – 6.5 ετών, εκ των οποίων τα είκοσι ήταν τυπικής ανάπτυξης και τα δέκα με Αναπτυξιακή Γλωσσική Διαταραχή. Όλα τα παιδιά εξετάστηκαν προ-πειραματικά με σταθμισμένα και μη σταθμισμένα εργαλεία αξιολόγησης γλωσσικών ικανοτήτων. Το κύριο πειραματικό μέρος περιελάμβανε  αξιολόγηση εξαγωγής συμπεράσματος, η οποία πραγματοποιούνταν με είκοσι σύντομες ιστορίες πολλαπλής επιλογής. Οι ιστορίες παρουσιάζονταν προφορικά στα παιδιά, τα οποία καλούνταν να επιλέξουν μία από τις τρεις διαθέσιμες απαντήσεις στις ερωτήσεις που τους είχαν τεθεί. Τα αποτελέσματα έδειξαν πως η ομάδα των παιδιών με ΑΓΔ σημείωσε στατιστικά χαμηλότερα ποσοστά επιτυχίας σχεδόν σε όλες τις ιστορίες (εκτός από δύο) σε σχέση με τα τυπικώς αναπτυσσόμενα. Συμπεραίνεται πως τα παιδιά με Αναπτυξιακή Γλωσσική Διαταραχή έχουν δυσκολίες στην εξαγωγή συμπεράσματος, όπως επιβεβαιώνεται και από τη διεθνή βιβλιογραφία. Συζητούνται οι επιπτώσεις για την αξιολόγηση και θεραπευτική παρέμβαση.
Angelus eius est (Act 12, 15)
Authors: Blanco-Sarto Pablo
Published: February 2023

San Josemaría tuvo siempre una devoción a los santos ángeles, fundamentada no solo en su experiencia personal sino sobre todo en la Escritura, en los Padres y en una teología que recorre los siglos, tanto en Oriente como en Occidente. El Doctor Angélico constituye una síntesis y una autoridad en el tema. También san Josemaría proponía una cercanía y una familiaridad que nos conducía a su Creador. La presencia de ángeles le infundía presencia de Dios, y por eso consideró siempre un “gran cómplice” al ángel de la guarda. Pero la función más excelsa de los ángeles está íntimamente unida a la celebración litúrgica y, de un modo especial, a la Eucaristía. San Josemaría quería verla siempre rodeada de ángeles adorando.
Shape of the Future
Authors: Roper Jack
Published: February 2023

Engineers are developing quieter and more efficient propellers using innovative wind tunnel testing technology
Commercial Spaceport Testing Facilities
Authors: Williams Andrew
Published: February 2023

A global market for spaceports is developing as the race to commercialize gathers pace
Metals Under the Microscope
Authors: Sampson Ben
Published: February 2023

Engineers are using the latest technology and developing new techniques to better understand metals at the microstructural and nanoscale level
Tomorrow Man
Authors: Sampson Ben
Published: February 2023

Jean Botti, CEO of VoltAero discusses the development progress of the Cassio hybrid-electric aircraft and the journey to more sustainable aviation
Controlling Complexity
Authors: Sampson Ben
Published: February 2023

Derrick Hinton, chair of the International Telemetering Conference (ITC) 2020-2021, discusses dealing with the increasing complexity of systems under test, 5G, cyber security and preparations for next year’s conference
Team working
Authors: Sands Glenn
Published: February 2023

The testing of interoperability between drones and manned aircraft poses a number of challenges for engineers
A Teacher’s Guide to Copyright, Fair Use, and Creative Commons in the United States
Authors: Shepherd Craig
Published: February 2023

This multi-day lesson introduces preservice teachers to copyright laws and how they influence resource use. The lesson also introduces fair use principles and components of a fair use claim before describing the limitations of fair use for practicing teachers. Creative Commons licenses are then introduced and explained as a better approach for resource use. Creative Commons resources are still protected by copyright law. However, the authors/owners of these works automatically grant some use rights under specified conditions. This granting of rights leads to a discussion about open education resources (OER). After this discussion, learners discover how to locate Creative Commons resources, cite them, and use them appropriately.
Time: Two, 50-minute classes
Cybersecurity: Introduction to Steganography
Authors: Balogun Aishat
Published: February 2023

This is part of a series of lessons that teach 9th-12th graders about cybersecurity. This lesson begins with a reminder to the students about ethics and cybersecurity and is followed by a problem scenario that introduces the topic of steganography. Students are expected to contribute and explore options and solutions to the problem scenario, followed by a lesson on steganography where students will practice creating their own steganography models as examples. This lesson concludes by having the learners exchange their finished projects (a game) for fellow students to decode the clues as they play the game.
Programming Bee-Bots to Draw Geometric Shapes
Authors: Alqahtani Muteb , Hall Jacob
Published: February 2023

This article describes an activity that integrates Bee-Bot robots, to engage first-grade students in creating different geometric shapes. In this activity, students work collaboratively to program Bee-Bots to move on a specific path with two markers attached to the Bee-Bots to create a geometric shape on a sheet of paper. After exploring the robots, first-grade students are asked to create geometric shapes such as squares, rectangles, and circles. Students write and test their programs, then observe the drawing to debug their program. This allows students to attend to the number of sides and vertices and the relations among them to complete the task.
Sphero Versus Dragon Ball-Z
Authors: Johnson Brian T. , Bramwell Rebecca
Published: February 2023

The lesson begins with a challenge to complete a specific course using a Sphero Spark Plus robot. Spheros were selected for this activity since they provide students with highly engaging opportunities to engaging in productive struggle to master mathematical concepts (Wheeler, Smith & Gardner   ,2020).  Through questioning, students review properties of right triangles, the Pythagorean Theorem, and protractor use before strategically block-coding a path through the course. Students were given a traced practice course, but the final test was to take their Sphero to the “official track” which had bumpers. Will their code be accurate enough to successfully navigate the course? 

Topics:
Considering Structure in Online Learning
Authors: Shepherd Craig E.
Published: February 2023

This week-long, asynchronous online module introduces the theory of transactional distance, particularly the component associated with structure, to graduate-level instructional design students enrolled in a seminar course about online learning. Learners were also introduced to publicly available Quality Matters rubrics and other readings associated with the effective design of online instruction. To demonstrate their understanding of the topic, learners imported skeletal learning resources into a course shell and developed them further in terms of sequence, clarity, organization, and purpose based on assigned readings and discussions. Because dialogue and accessibility concepts were covered more fully in later modules, these topics were minimized during this module.

Topics: distance education, online learning, learning management system, course design, structure, clarity, organization.

Time:  One week was allocated for this lesson.
Taking the Great Leap Forwards: Teaching Woody Guthrie in the College Classroom
Authors: Fazio Michele , Zoeller Aimee , Fernandez Mark F. , Carney Court , Stadler Gustavus
Published: February 2023

This essay explores the work of Woody Guthrie and other folk artists who have followed in his tradition of documenting working-class people’s experiences in song. In addition to outlining the creation of the Teaching Woody Guthrie Faculty Learning Collective–a group of teacher-scholars, activists, and musicians who are dedicated to collaborating across disciplines to illustrate Woody Guthrie’s relevance in today’s precarious world–the essay includes suggested curriculum to teach folk music and political activism in the college classroom.
How COVID Vaccination Hesitancy, Social Class, and Economic Inequality Reveal a New Dimension of Public Trust
Authors: Kohn Liberty
Published: February 2023

COVID vaccination data on United States’ citizens reveals that working-class citizens across multicultural domains and political identities are vaccinating at lower rates because working-class citizens do not feel that public institutions have met obligations to improve their life. This belief in unmet obligations illustrates a new facet of institutional trust: a general indifference to institutional requests. This indifference to institutional request, with indifference as a new dimension of trust, differs from past working-class scholarship on institutional trust, which often finds anger, submission, or scapegoating other groups as common responses to institutional request or rhetoric. This article also recapitulates the strong relationship between the U.S.’s high economic inequality and working-class lack of trust and indifference toward public institutions.
Colonialism, eugenics and ‘race’ in Central and Eastern Europe
Authors: Turda Marius , Balogun Bolaji
Published: February 2023

The legacies of eugenics in Central and Eastern Europe (CEE) and their connections to global colonialism remain uncharted. Therefore, it is worth pondering over this relationship, which requires a historical perspective and a repositioning of the recent postcolonial ‘turn’ in CEE to include the history of eugenics. For the most part of the 20th century, eugenics took shape within both colonial and nation-building projects. Eugenic strategies devised to preserve the colonial system outside Europe have always coexisted with programmes designed to improve the well-being of nations within Europe. This convergence between colonial, racial and national dimensions of eugenics requires a critical rethought. While this key line of inquiry has been a major focus in Western Europe and the US, it remains under-theorised in CEE. By highlighting the colonial implications of nation-building in the region, we attempt to destabilise the all-too-pervasive historiographic misconception that CEE nations are largely untouched by the global circulation of eugenics and scientific racism.
On the Geometrical Relation between the Color Spaces of Normal and Anomalous Trichromats
Authors: Wagner H. G.
Published: February 2023

Any color stimulus can be specified by its (relative) spectral radiant power distribution S(λ). Usually this distribution is given as S(λi) at n discrete wavelengths λi (i = 1…n), λi ranging in the visible part of the spectrum.
Testing for Acquired Color Vision Deficiencies in Patients Receiving Hydroxychloroquine (Plaquenil) Therapy
Authors: Cyert Lynn
Published: February 2023

Hydroxychloroquine sulfate--trade name Plaquenil--is an antimalarial therapeutic agent derived from chloroquine. Hydroxychloroquine is also important for its use as an anti-inflammatory agent in the treatment of rheumatoid arthritis and discoid and systemic lupus erythematosus(1).
What Causes Linearity Failure in Color Matching?
Authors: Burns Stephen A. , Elsner A. E.
Published: February 2023

Color matching data provides the basic data set for derivations of the cone photopigment fundamentals. Central to the power of the color matching technique is its property of linearity, which presumably arises from the univariance of the photoreceptors. However, there are three well-known experimental conditions which cause failures of linearity. These conditions are changes in test field size (the color-match area-effect), increasing the retinal illuminance above about 5000 td (the color-match illuminance effect), and changing the point of pupil entry of the color matching field (the Stiles-Crawford II effect). Explanations for these effects include changes in the optical density of the photopigments9, and changes in the wavelength dependent waveguide properties of the cones. Previous studies2,6,10, have argued that neither the illuminance effect nor the SC II effect can be explained by optical density, however these studies rely on computational models of the effect of pupil entry and bleaching. In this paper we directly manipulate the optical density of the cones by bleaching.
Four Separate Mechanisms for Interaction between "Red Cones" and Rods
Authors: Frumkes Thomas E.
Published: February 2023

For the past 20 years our laboratory has investigated interactions between rods and the "red-cone" (long wavelength or Stiles Pi5) mechanism using psychophysical procedures in humans, and neurophysiological procedures in humans and lower vertebrates. To date, we have discerned 4 separate mechanisms for interaction.
Color constancy: adaptation to the illumination environment
Authors: D'Zmura Michael , Iverson Geoffrey
Published: February 2023

Theoretical work on color constancy has dwelt on the problem of estimating surface and illuminant chromatic properties in the case where a set of surfaces is viewed under a single illuminant1-5. Maloney and Wandell4used linear models to describe variation among surface reflectance functions6-9and variation among illuminants10,11to establish a general result for this situation: a trichromatic system viewing surfaces under a single unknown illuminant that is represented by three color descriptors can recover two color- constant descriptors per surface. Their remarkable result is incomplete, however. First, it is desirable to recover three or more descriptors per surface, for neither surface color percepts12nor surface color properties6-9are described adequately by two-dimensional models. Second, one would prefer the recovery of surface reflectance descriptors to be independent of the choice of a particular model of illumination. The model that describes accurately the daylight illumination environment10,11, for instance, will generally fail to describe other illumination environments such as those found indoors or that presented by the red, green and blue lights used in Land's demonstrations with Mondrians1.
Spatial Blackness Induction at Different Blackness Levels
Authors: Shinomori Keizo , Nakano Yasuhisa , Uchikawa Keiji
Published: February 2023

In previous papers1-5), blackness at fixed criteria have been measured by a method of adjustment and spectral efficiencies of blackness were obtained. In this research, the spatial blackness induction was measured as a function of log retinal illuminance of monochromatic inducing-field using a color naming method and a method of adjustment and then the spectral efficiencies of blackness induction at three different criteria, black=95%, black=white and black=5%, were obtained.
Threshold displacement size for perceiving a stable stimulus across saccades: effects of equiluminance
Authors: Ishida Taiichiro , Shinoda Hiroyuki , Ikeda Mitsuo
Published: February 2023

We perceive the external world as stable despite saccadic eye movements. How this is achieved has been one of the important problems in the field of vision research. In recent years, several studies have shown that the subject can perceive a stable stimulus even if the stimulus is displaced a certain amount during saccades.1-4) In our previous study, 2) we found that tolerable displacement size for perceiving a stable stimulus was influenced by properties of a stimulus. The subject tended to detect movements in the parts of a picture that appeared conspicuous. On the other hand, the subject was not able to notice movements in rather homogeneous parts of the picture. It remains to be elucidated what features of a picture have an effect on integrating visual information across saccades.
Laser and Natural Guide Star Measured Turbulent Wavefront Correlation
Authors: Deron Ruy , Laurent Sylvain , Séchaud Marc , Rousset Gérard
Published: February 2023

The laser guide star concept was proposed for the application of adaptive optics in astronomy in order to overcome the problem of natural star requisite brightness which significantly limits the sky coverage [1, 2]. Recently, the adaptive optics compensation of turbulent wavefront using laser guide star has been demonstrated [3,4].
Post-detection Correction of Compensated Imagery using Phase-Diverse Speckle
Authors: Seldin John H. , Paxman Richard G. , Ellerbroek Brent L.
Published: February 2023

Developments in adaptive-optics technology have allowed astronomers using ground-based telescopes to overcome much of the loss of resolution due to aberrations introduced by the intervening atmosphere. Although adaptive-optics systems work quite well, they have their limitations and regimes of operation, and residual aberrations are often a problem. While research into expanding the capabilities of pre-detection correction continues, post-detection restoration of ground-based astronomical data is still desired and often required. Over the years, researchers have developed a variety of clever post-detection techniques for recovering image resolution, including stellar speckle imaging and deconvolution from wavefront sensing. We have been applying a novel data-collection and processing approach to correct for the effects of atmospheric seeing called phase-diverse speckle imaging. Phase-diverse speckle imaging has been used recently to restore images of solar granulation [1], and we present here the first application of this technique to nighttime astronomy data.
The ESO VLT Adaptive Optics program
Authors: Hubin N.
Published: February 2023

Adaptive optics is one of the main features of the Very Large Telescope of the European Southern Observatory (ESO). Use of the large telescopes for high spatial resolution imaging, high spectral resolution spectroscopy and astronomical spatial interferometry depends substantially on the availability of adaptive optics, which allows diffraction limited imaging in the near infrared wavelength range (2.2 to 5 microns) and partial correction of atmospheric distortions towards the visible wavelength range.
ADONIS A user-friendly adaptive optics system for the ESO 3.6 m telescope
Authors: Beuzit J.L. , Hubin N. , Demailly L. , Gendron E. , Gigan P. , Lacombe F. , Rouan D. , Chazallet F. , Rabaud D. , Madec P.Y. , Rousset G. , Eisenhauer F. , Hofmann R. , Prieto E. , Bonaccini D.
Published: February 2023

The first astronomical results obtained at the ESO 3.6 m telescope with the Come-On adaptive optics system demonstrated the impressive potential of this technique [1,2,3], A second generation of this system [4], called Come-On-Plus, has since been developed and tested at La Silla observatory [5], It is now the only system of this kind offered as a standard instrument to the European astronomical community. Nevertheless, adaptive optics remains a high technology technique which uses complex technology. Although the Come-On and Come-On-Plus systems have operated very smoothly during numerous observing runs since 1990, a fairly large team of qualified personnel was required to operate the whole system. Several instrumental parameters have to be optimised according to astronomical requirements and prevailing atmospheric conditions. These include the magnitude and colour of the reference star, the wavelength of the observed object and its angular separation from the reference, and the atmospheric turbulence profile. With the previous Come-On-Plus system this optimisation was difficult to achieve and has given rise to somewhat inefficient use of telescope time. The experience gained with this system has led to the concept of ADONIS (ADaptive Optics Near Infrared System), which is intended to improve the performance, versatility and operational efficiency. A further general objective is to develop operational procedures and to test technical concepts that can be later applied to the adaptive optics system for the ESO Very Large Telescope.
Synthesis of Optimal Regulators for Segmented Mirror Figure Control
Authors: Lavrov Nicolay A. , Sidorov Victor I.
Published: February 2023

This report is devoted to the method of optimal regulator synthesis for the control of segmented mirror surface form. It is important to develop a method of optimal synthesis of the control system, meeting the “basic” functional criterion as well as the given dynamic characteristics of segmented mirror.
Comparison of Adaptive-Optics Technologies for Large Astronomical Telescopes
Authors: Rigaut François , Ellerbroek Brent L. , Northcott Malcolm J.
Published: February 2023

The emergence of new wavefront sensing techniques, such as wavefront curvature sensing, opens new pathways for astronomical adaptive optics. Even though the advantages and drawbacks of Shack-Hartmann and curvature wavefront sensing are known [1,2], no direct comparison of complete systems has yet been presented. The goal of this paper is to investigate and compare the performance of Shack-Hartmann and curvature based systems for an eight-meter telescope, evaluated at a 1.6 µm wavelength under typical Mauna Kea seeing conditions. This work was made at the request of the Gemini adaptive optics working group, who asked three independant parties to perform adaptive optics system simulations using both technologies. To make the comparison simple enough, a set of conditions was imposed on seeing, telescope size, and wavefront sensor detectors. Independant simulation codes were used. A common atmospheric turbulence generator provided consistant inputs for all packages.
Techniques for Optical Fabrication of a 2-mm-thick Adaptive Secondary Mirror
Authors: Martin H. M. , Anderson D. S.
Published: February 2023

As part of the conversion of the Multiple Mirror Telescope from six 1.8 m mirrors to one 6.5 m primary mirror, the telescope will be equipped with an adaptive f/15 secondary mirror optimized for the near infrared, λ = 1−5 µm. This mirror is a thin shell, 2 mm thick and 640 mm in diameter, supported on 320 voice-coil actuators which are mounted in a rigid substrate. A capacitive sensor at each actuator provides closed-loop position control with much higher bandwidth than the wavefront sensor alone allows. The geometry of the secondary is given below.
Feedback Interferometry for Aberration Correction
Authors: Barnes T.H. , Bold G.T. , Haskell T.G.
Published: February 2023

Feedback interferometers, in which the output fringe pattern is fed back to modulate the phase-difference in the interferometer via a spatial optical phase modulator, have been used for investigations of spatial structure formation1, optical memories2, and to achieve unambiguous fringe phase display for optical testing3. If these interferometers are operated in the negative feedback regime, it is possible to obtain output fringe patterns where intensity is almost linearly dependant on the physical path-difference in the system. This intensity distribution is fed back to a phase modulator in the interferometer as part of the negative feedback scheme, and so the resultant phase modulation partially cancels the interferometer path-difference - the degree of cancellation depending on the gain of the feedback loop. With an appropriate interferometer system (for example a radial shearing interferometer) it is, in principle, possible to automatically correct the aberrations of the input wavefront even at low optical powers4. We have built an interferometer of this type and describe its characteristics here.
Imaging by Low order Adaptive Optics
Authors: Holohan M.L , O’hUallacháin M.L
Published: February 2023

As the use of optics in industrial and medical applications becomes more widespread the problems of maintaining desired optical properties during transmission through turbulent media has come to the fore. Much work has been done modelling optical transmission through such media [1, 2]. Adaptive optics (AO) is the name given to systems which continually monitor the incoming light and attempt to maintain the beam or image quality. The need for low cost adaptive optics will only grow as new applications develop.
Interferogram Evaluation by 4D Analytic Signal Theory
Authors: Tartakowski Valeri A.
Published: February 2023

Application of the well-known principle of heterodyning was first described in Ref. 1 as the Fourier transform method for phase restoration from interferogram and in Ref. 2 as the analytic signal method for designing an interference wave-front sensor. Here we discuss a development of the latter, and go into unknown essential details of it.
Relation between Conjugation Error and Inverted Field Intensity Deviation
Authors: Tartakowski V. A. , Myer N. N.
Published: February 2023

Adaptive optical systems use reciprocity1 working through the turbulent atmosphere. An influence of input errors on output errors must be cleared up originally for some systems. It is interesting to elucidate relations between the conjugation error εc, which arises as a result of some modification of the conjugated field in the receiving plane, and the inverted field intensity deviation εo from the original field intensity in the source plane.
The Influence of Wave Front Dislocations on Phase Conjugation Instability at Thermal Blooming Compensation
Authors: Fortes Boris V. , Lukin Vladimir P.
Published: February 2023

The present paper is devoted to the application of the phase conjugation method for the thermal blooming compensation. This problem was discussed previously in a series of papers of different authors1,2,3,4,5,6,7, and the results of these papers indicate of the fact that the phase conjugation application for correction of nonlinear distortions of high power laser beams has some specific features including the instabilities of different type. At the homogeneous horizontal paths the instability appears as parameters oscillations of corrected and reference beams, and at vertical paths the small-scale instability is developed.
Efficiency of Adaptive Correction of Images in a Telescope Using an Artificial Guide Star
Authors: Lukin Vladimir P. , Fortes Boris V.
Published: February 2023

It is well known that the use of a bright natural star as a reference source is limited by the angle of isoplanarity1,2,3 which usually does not exceed 10 angular seconds, while the sufficiency bright stars are located less closely. In this connection in recent years the formation technique of artificial guide stars is gathering force, based on the effect of laser backscattering in the atmosphere4,5.
Single-Frequency Nd:YAG Lasers as a Light Sources for Wave front Sensors Interferometers
Authors: Parfenov Vadim A. , Seregin Alexander G. , Rodin Sergei N. , Kruzhalov Sergei V. , Parfenov Vladimir A.
Published: February 2023

Wave front sensors with an internal reference light source applied in the most of advanced adaptive telescopes use basically classic interferometric methods of optical surface testing and involve analyzing of the wave front reflected by the surface under test.
Proposed design for a scalable dye laser for use in sodium laser guide star generation
Authors: Hogan G P , Webb C E
Published: February 2023

In designing a laser system for application as a source for a sodium laser guide star there are a number of fundamental constraints which affect the design choices to be made.
Space-time Wavefront Analysis Using a Coordinate Remapping Shack-Hartmann Sensor
Authors: Wooder N J , Munro I , Nicholls T W , Wells M , Dainty J C
Published: February 2023

In this project, we wished to make the first measurements of the spatial-temporal characteristics of wavefronts in the infrared by taking advantage of the exisiting infrared camera (IRCAM3) and fast controller (ALICE) [1] at the 3.8m United Kingdom Infrared Telescope (UKIRT). The intention was to have a system that could eventually be used for routine measurements as part of the UK’s Joint Observatories Site Evaluation (JOSE) campaign: a re-engineered version of the system described here has in fact now been constructed for the JOSE programme.
Conceptual Design for a User-Friendly Adaptive Optics System at Lick Observatory
Authors: Bissinger Horst D. , Olivier Scot S. , Max Claire E.
Published: February 2023

In this paper, we present a conceptual design for a general-purpose adaptive optics (AO) system, usable with all Cassegrain facility instruments on the 3 meter Shane telescope at the University of California's Lick Observatory located on Mt. Hamilton near San Jose, California. The overall design goal for this system is to take the sodium-layer laser guide star adaptive optics technology out of the demonstration stage and to build a user-friendly astronomical tool. The emphasis will be on ease of calibration, improved stability and operational simplicity in order to allow the system to be run routinely by observatory staff.
Adaptive Optics for a 70 cm Solar Telescope
Authors: Soltau D. , Acton D.S. , Kentischer Th. , Roser M. , Schmidt W. , Stix M.
Published: February 2023

The sun is a bright, low-contrast, extended object. One arcsecond corresponds to 725 km on the sun. In the solar atmosphere the density scale height and the photon mean-free-path are both ~100 km. Due to the large conductivity, the solar magnetic field has an extremely inhomogenous structure with a typical scale of 100 km or even less. In order to resolve 50 km on the sun, a telescope should have an angular resolution of 0.07 arcsec. In the visible (λ=500 nm), this would require an aperture of about 2 m.
Current status of the Oxford Scalable Sodium Laser Guide Star System
Authors: Hogan G.P. , Booth H. , Montandon-Varoda L. , Webb C.E.
Published: February 2023

Oxford is currently designing a scalable laser system to generate a sodium layer laser guide star (LGS) for astronomical adaptive optics. The emphasis in our design is upon an architecture that allows the average output power of the system to be increased arbitrarily without increasing peak power, and thus saturation level in the sodium layer. It is intended that in this way a system may be designed that, once installed, may be enlarged in the confidence that additional power launched will result in additional photons returned.
Adaptive Optics Specification for a 10m Telescope on the ORM
Authors: Devaney Nicholas
Published: February 2023

The Spanish astronomical community has decided to build a 10m telescope employing a segmented primary mirror in the Observatorio del Roque de los Muchachos (ORM) on the island of La Palma in the Canary Islands. The telescope will incorporate an Adaptive Optics (AO) facility and work is underway to specify the requirements for this system. The AO requirements are being drawn up at this early stage so that they may be taken into account in the detailed optical and mechanical design of the telescope. In particular, the ability to carry out AO at the shortest wavelengths feasable should not be limited by errors in the phasing and tilting of the primary mirror segments. The form of the PSF and the Strehl ratio dependance on these errors is examined by Fourier transforming a simple simulation of the segmented mirror. The simulation includes inter-segment correlation of the piston errors.
Optimal Estimators for Astronomical Adaptive Optics
Authors: Wild Walter J.
Published: February 2023

An adaptive optics system is a closed-loop servo control system that seeks to maximize PSF Strehl ratio performance by minimizing wavefront distortions. The wavefront is sampled over discrete subapertures and the local slopes are used to estimate the instantaneous wavefront shape which is then used to drive a deformable mirror with a discrete array of actuators. The temporal and spatial performance of the system is embodied in a single mathematical descriptor of the form Γ is a covariance matrix of the error between the atmosphere phase φ(ti+1) at time ti+1 and the deformable mirror figure, ϕdm(ti), derived from measurements at the previous time ti. Boldface quantities are vectors and matrices. The phase reflecting off the mirror is φ(ti+1) – ϕ(ti), presently assuming that ϕdm(ti)≈ϕ(ti), where ϕ(ti) is the estimated wavefront phase. Covariance matrices are a powerful mathematical tool because they contain information, in an ensemble average sense, about the sources of error and correlations present in the system. From Γ, the Strehl ratio, the MTF, time-delay, etc., can be computed. The Strehl ratio in the Marechal approximation is S ~ exp(–σ2), where σ2=Tr(Γ) /Na, for Na actuators within the pupil.
Optimization of Adaptive Optics Digital Imagery Systems by Design of Experiments
Authors: Brigantic Robert T. , Roggemann Michael C. , Bauer Kenneth W. , Welsh Byron M.
Published: February 2023

Adaptive optics systems are still a relatively new technology. As such, characterization of their performance under a given set of conditions still has many uncertainties. For instance, even though many variables for a particular imaging scenario are uncontrollable, such as seeing conditions, object brightness (visual magnitude), and object size/distance, many other Adaptive Optics System (AOS) parameters can be controlled by the system operator. These include system integration time, imaging and Wavefront Sensor (WFS) wavelengths, closed loop bandwidth, image exposure time, and others. Selecting parameter settings for these variables to yield the “best quality” image is far from obvious. Further, what does the “best quality” image mean?
Discrete-zonal method for widening field of view of adaptive telescope
Authors: Podoba V.I. , Bonshtedt B.E. , Koreshev S.N. , Lakhtikov V.B. , Lebedeva G.I. , Seregin A.G. , Yeskov D.N.
Published: February 2023

At present some large-scale programs are carried out in various countries that are aimed towards development of a new class of ground and space-based telescopes. Principal features required for modern telescopes are following: wide spectral range (from 0.2 up to 1000 mkm), high angular resolution of the order of 0.02 arcsec, large angular field of view (FOV) up to 1 degree´, minimal dimensions and weights.
“1001” Correlations in Random Wave Fields
Authors: Freund Isaac
Published: February 2023

The coherence length Λcoh of a random wave field E(x,y) is defined as the characteristic distance over which the whole field, ensemble averaged autocorrelation function μ(Δx)= /<|E(x,y)|2> decays to zero [1] A natural, indeed universal interpretation is that on length scales larger than Λcoh, different field structures such as maxima, minima, etc. are uncorrelated. Indeed, it is the apparently random distributions of positions, heights, and widths of these features that make the field appear “random”. But as is often the case, appearances can be deceiving, and we have recently found that there are literally thousands of unexpected, often highly unusual, local correlations and anticorrelations present even in that apparently most random of all wave fields, the Gaussian field (i.e. a field whose fundamental field variables obey Gaussian statistics). These local correlations tend to be paired such that correlations with μ ~ +1 in one region of the wave field are exactly canceled by anticorrelations with μ ~–1 in other regions, leading to a whole field average μ ~ 0. Many of these correlations are topological in nature, and are thus universal features of all wave fields. Knowledge of these universal correlations may prove useful in the manipulation and reconstruction of a variety of abberated fields.
Numerical simulation of steady-state thermal blooming with natural convection
Authors: Lane Jeremiah S. , Cook Justin , Richardson Martin , Akers Benjamin F.
Published: February 2023

This work investigates steady-state thermal blooming of a high-energy laser in the presence of laser-driven convection. While thermal blooming has historically been simulated with prescribed fluid velocities, the model introduced here solves for the fluid dynamics along the propagation path using a Boussinesq approximation to the incompressible Navier–Stokes equations. The resultant temperature fluctuations were coupled to refractive index fluctuations, and the beam propagation was modeled using the paraxial wave equation. Fixed-point methods were used to solve the fluid equations as well as to couple the beam propagation to the steady-state flow. The simulated results are discussed relative to recent experimental thermal blooming results [Opt. Laser Technol.146,107568(2022)OLTCAS0030-399210.1016/j.optlastec.2021.107568], with half-moon irradiance patterns matching for a laser wavelength at moderate absorption. Higher energy lasers were simulated within an atmospheric transmission window, with the laser irradiance exhibiting crescent profiles.
Spectral Ellipsometer based on the Polarization-Holographic Diffraction Element
Authors: Kilosanidze B. , Kakauridze G. , Chaganava I. , Kobulashvili I. , Mshvenieradze Yu.
Published: February 2023

A new method of determining ellipsometric parameters and their dispersion based on only one polarization-holographic diffraction element is suggested by simultaneous measurement of the intensities of the diffraction orders and by using the appropriate software.