Mirror Test Research Articles

Full-aperture surface reconstruction method for shift-rotation absolute measurement with tilt error suppression

We propose a new surface reconstruction method for the absolute measurement of shift rotation that can obtain a full-aperture surface distribution. Our approach reduces the effect of tilt errors on surface reconstruction by increasing the translation ratio of the test mirror. This method requires the test mirror to be measured once in situ, after translation, and after rotation. Because the known measured wavefront is a nonlinear function of the absolute surface distribution, the function of the surface distribution is linearized by performing a Taylor expansion to achieve fast surface reconstruction. Finally, a linear system of equations is constructed to solve the absolute surface distribution. The coefficient matrix is sparse and can quickly and accurately reconstruct the absolute surface distribution. In the simulation, the root mean square error (RMSE) of the reconstructed surface distribution of the method discussed in this study can reach to 0.012nm. Moreover, our method can significantly reduce the effect of tilt errors compared with typical methods, thereby yielding a new, high-precision solution for absolute measurements in interferometry.

Mixed compensation for the testing of large convex aspheres

Since the testing of convex mirrors often requires a compensator with a larger aperture than the mirror under test, this is undoubtedly a trade-off not worth pursuing. Moreover, for surfaces with higher levels of asphericity, it further escalates the challenges in testing. In this study, high-accuracy testing of large convex aspheric surfaces with rotary symmetry was achieved via a method that combines sub-aperture stitching and Computer-Generated Holograms (CGH) compensation testing. Applying the methodology outlined in this study, practical testing was conducted on a large-aperture convex aspheric mirror with a diameter of 538 mm. The outcomes demonstrated that the center testing data and the outer ring testing data were stitched by the stitching algorithm to obtain the surface error of the full-aperture. The results were compared to those of Luphoscan and compensation testing, with a residual Root Mean Square (RMS) less than λ/20 (λ = 632.8 nm). Finally, the error analysis of the entire testing process showed that the accuracy was better than λ/50. The results demonstrate that the method can achieve highly accurate test of large convex aspheric surfaces.

Temperature dependence of the thermal conductivity of hydroxide catalysis bonds between silicon substrates

Future generations of gravitational wave detectors plan to use cryogenics in order to further reduce thermal noise associated with the mirror test masses and their suspensions. It is important that the thermal conductivity of candidate materials for these mirror suspension systems, and any additional thermal resistance associated with the required bonding/jointing, is characterised. Results are presented here for composite single-crystal silicon substrates, with multiple hydroxide catalysis bonds present, in order to assess the thermal conductivity of the bond layers. An average bond thickness of nm is observed within the oxide-bond-oxide interfaces, with a calculated thermal conductivity rising from Wm−1K−1 across a temperature range of K. This confirms that the thermal conductance through hydroxide catalysis bonds, with geometries being considered for third generation gravitational wave detectors operating at 20 K or 125 K, would have a negligible impact on the required heat extraction for cryogenic operation. Therefore, the use of hydroxide catalysis bonding, as successfully demonstrated within room temperature gravitational wave detectors, remains an attractive solution for building future cryogenic instruments with reduced thermal noise and enhanced astrophysical reach.

Neuropeptide Y receptor Y2 (npy2r) deficiency reduces anxiety and increases food intake in Japanese medaka (Oryzias latipes).

Neuropeptide Y receptor Y2 (npy2r) is an important receptor gene involved in anxiety and feeding regulation in mammals. Since NPY receptors have different receptor gene deletions in mammals and teleost fish, it is not clear whether npy2r has the similar function in fish as in mammals. In this study, we used the CRISPR/Cas9 system to establish npy2r-deficient medaka (Oryzias latipes). Unexpectedly, the deletion of npy2r resulted in the npy2r +/- medaka were all-male, therefore, npy2r homozygous mutant lines could not be established. The deletion of npy2r increased the food intake in medaka, and the expression levels of appetite stimulating genes (agrp, npy) increased significantly, while the expression levels of anorexia factors (cck, pomc) decreased significantly. Moreover, the absence of npy2r significantly increased the total length and body weight of medaka. The mirror test and open field test showed that npy2r +/- medaka improved sociability and reduced anxiety-like behavior, qRT-PCR analysis showed that the expression levels of anxiety related genes (th1, th2, gr1, gr2, and mr) in npy2r +/- medaka were significantly decreased. So far, this is the first npy2r gene knockout model established in fish and demonstrates that npy2r plays an important role in the regulation of reproduction, feeding and anxiety in fish.

Maintaining Tensions: Braiding as an Analogy for Mathematics Teacher Educators’ Political Work

Although the field of mathematics education has made gains in centering the need for justice-oriented approaches and antiracist teaching practices in teacher education, much of this work remains in its infancy. Moreover, research focused on this area highlights teacher candidates’ knowledge and dispositions and often ignores the role of the mathematics teacher educators facilitating the process. We contend that mathematics teacher educators must pay more attention to how intersectional identities, contexts, Mirror Tests, and principles of Rehumanizing Mathematics manifest in teacher education to better understand how teacher candidates develop political knowledge in teaching mathematics. To this end, we introduce a framework of considerations, which we call a compass, that identifies four dimensions (or strands) and offers guiding questions for mathematics teacher educators to consider. We offer examples from a multi-site research study to illuminate each dimension and build the case for the necessity of braiding the four strands together as we engage in this line of work. Implications for practice and future research are discussed.

Impact of ion irradiation and film deposition on optical and fuel retention properties of Mo polycrystalline and single crystal mirrors

Polycrystalline (PC) and single crystal (SC) molybdenum mirrors were irradiated with 98Mo+, 1H+, 4He+, 11B+ and 184W+. Energies were chosen to impact the optically active region (up to 30 nm deep) of Mo mirrors. Some surfaces were coated by magnetron sputtering either with B or W films 4–65 nm thick. The overall objective was to simulate the neutron-induced damage and transmutation (H, He), and the impact of H, He, B, W on the optical performance of test mirrors, and on fuel retention. In parallel, a set of PC Mo mirrors irradiated with 1.6 MeV 98Mo3+ to a damage of 2 dpa and 20 dpa was installed in the JET tokamak for exposure during deuterium-tritium campaigns. Data from spectrophotometric, ion beam and microscopy techniques reveal: (i) the irradiation decreased specular reflectivity, whereby the differences between PC and SC in reflectivity are very small, (ii) He is retained in bubbles within 25–30 nm of the subsurface layer in all irradiated materials, (iii) W, either deposited or implanted, decreases reflectivity, but the strongest reflectivity degradation is caused by B deposition. Laboratory studies show the correlation of damage and H retention. Several cycles of W deposition and its removal from SC-Mo mirrors by plasma-assisted methods were also performed.

Roosters do not warn the bird in the mirror: The cognitive ecology of mirror self-recognition.

Touching a mark on the own body when seeing this mark in a mirror is regarded as a correlate of self-awareness and seems confined to great apes and a few further species. However, this paradigm often produces false-negative results and possibly dichotomizes a gradual evolutionary transition of self-recognition. We hypothesized that this ability is more widespread if ecologically tested and developed such a procedure for a most unlikely candidate: chickens (Gallus gallus domesticus). Roosters warn conspecifics when seeing an aerial predator, but not when alone. Exploiting this natural behavior, we tested individual roosters alone, with another male, or with a mirror while a hawk's silhouette flew above them. Roosters mainly emitted alarm calls in the presence of another individual but not when alone or seeing themselves in the mirror. In contrast, our birds failed the classic mirror test. Thus, chickens possibly recognize their reflection as their own, strikingly showing how much cognition is ecologically embedded.

Analysis and experiment of a pneumatic-hydraulic composite support system for in-situ mirror processing and testing.

To address the deformation issues caused by the self-gravity and machining stresses in the process of large-aperture mirror fabrication, this paper proposes an in-situ switchable pneumatic-hydraulic hybrid supporting system that enables the seamless transition between machining and testing. By facilitating in-situ switching, this system not only reduces the machining time of large-aperture mirrors, thereby enhancing production efficiency, but also mitigates the risks associated with traditional switching methods that may result in mirror damage due to human error. Three typical working conditions of the hybrid supporting system, namely hydraulic machining support, air-floating testing support, and three-point rigid support, are investigated in terms of mirror loading through a finite element simulation. Additionally, an experimental platform is constructed to validate the proposed system. The experimental results affirm the feasibility of the designed pneumatic-hydraulic hybrid supporting system. This system will serve as a technological support to advance the rapid development of large-aperture space telescope manufacturing techniques.

Self-perception and self-recognition while looking in the mirror on psilocybin

AbstractIntroductionIt is not known how self-perception and self-recognition are influenced when one is highly self-focused under the influence of psilocybin. Here we examine self-reports of mirror self-recognition and self-perception during a psilocybin experience.MethodsReddit posts were examined in a systematic manner. Posts that were written by individuals that ingested psilocybin and subsequently looked in a mirror were examined. After both automatic and manual filtering, a total of 89 posts with 775 post excerpts were analyzed.ResultsIt was found that it was rare to see one's own face as a different entity (e.g., an animal or other person) however people were equally likely to see themselves as they really are or distorted. People were significantly more positive than negative when perceiving their own face.DiscussionWe found wide variation in the perception of the own-face while under the influence of psilocybin. While generally positive, the self-face appears to be an experience that varies dramatically from person to person under the influence of psilocybin.

Aggression repeatability in stressed fish in response to an environmental concentration of sertraline and lunar cycle as evidenced by brain metabolomics

Sertraline is an environmental pollutant which received magnified scientific attention due to its global presence in waters. Adverse effects on feeding, reproduction and other traits were observed mostly in unstressed aquatic organisms. Chronic stress, however, induces significant physiological changes, and the effects of sertraline in stressed fish may differ from those observed in non-stressed individuals. The current laboratory study addresses this gap by repeatedly monitoring the individual aggression of chronically stressed juvenile chub (Squalius cephalus L.) using the non-reversing mirror test at an environmental sertraline concentration of 0.022 g/L every three to four days for a period of 39 days. Specifically, it was hypothesized that the level and repeatability of aggressiveness would be (i) correlated with the concentration of sertraline/norsertraline in the fish brain; (ii) linked to the individual brain metabolomic profile described by LC-HRMS analyses; (iii) related to the lunar cycle. Sertraline led to an increase in fish aggression and more repeatable/consistent behaviour compared to control fish. While the level of sertraline in the brain did not correlate with aggressiveness, aggressive responses increased with higher norsertraline concentration. The observed aggressive behaviour also varied depending on the individual metabolomic profile of the brain. The behavioural outcome and metabolic change in fish brain may indicate that sertraline has demonstrated neuroprotective effects by reducing cortisol release. It is possible that fish exposed to sertraline could suffer a blunted stress response under the chronic stressors in the wild. Aggressiveness of both treatments evolved in time, revealing a sinusoid-like pattern corresponding to a lunar cycle with a peak of the aggressiveness during the new moon. There is a need for future studies to focus on this relationship to reveal its details and general validity. Our results emphasize that long-term behavioural variability should generally be taken into account in laboratory behavioural studies.

Development of a low energy ion irradiation system for erosion test of first mirror in fusion devices

A low energy ion irradiation system based on the deuterium arc ion source with a high perveance of 1 μP for a single extraction aperture has been successfully developed for the investigation of ion irradiation on plasma-facing components including the first mirror of plasma optical diagnostics system. Under the optimum operating condition for mirror testing, the ion source has a beam energy of 200 eV and a current density of 3.7 mA/cm2. The ion source comprises a magnetic cusp-type plasma source, an extraction system, a target system with a Faraday cup, and a power supply control system to ensure stable long time operation. Operation parameters of plasma source such as pressure, filament current, and arc power with D2 discharge gas were optimized for beam extraction by measuring plasma parameters with a Langmuir probe. The diode electrode extraction system was designed by IGUN simulation to optimize for 1 μP perveance. It was successfully demonstrated that the ion beam current of ∼4 mA can be extracted through the 10 mm aperture from the developed ion source. The target system with the Faraday cup is also developed to measure the beam current. With the assistance of the power control system, ion beams are extracted while maintaining a consistent arc power for more than 10 min of continuous operation.

The effect of light during embryonic development on laterality and exploration in Western Rainbowfish

ABSTRACT Several factors affect the development of lateralization such as hormones and light exposure during early development. Laterality also often correlates with other behavioral traits. To examine whether there is a common mechanism underlying the development of laterality and other behaviors, we manipulated laterality by exposing embryos of the Western rainbowfish (Melatotaenia australis) to light or continuous darkness during early development and determined whether a shift in laterality was associated with a change in behavior in a novel environment test at two different ages. We found that exposing eggs to darkness led to offspring that displayed significantly less lateralized behavior in the mirror test two weeks after hatching than offspring from eggs exposed to light. Interestingly, the effects of rearing condition were lost by 3 months of age. These data suggest that exposure to light can influence laterality very early in development, but such bias can be overwritten by developmental processes post-hatch. Moreover, our manipulation of laterality apparently had no influence on exploration suggesting independent causal mechanisms. The experimental manipulation of light exposure during development could be a useful tool for enhancing individuals with a specific laterality and behavioral traits to aid future research into the causes and consequences of laterality.

Gonadotropin inhibitory-hormone modulates neurosteroids-synthesizing enzymes expression and aggressive behavior in male sea bass, Dicentrarchus labrax

Neurosteroids are involved in the regulation of multiple behavioral and physiological processes and metabolic activities in the vertebrate brain. However, central mechanisms of how neurosteroid synthesis is regulated is far to be understood. Gonadotropin-inhibitory hormone (GNIH) is a hypothalamic neuropeptide that negatively regulates gonadotropin secretion but also inhibits sexual and aggressive behaviors in birds and mammals by modulating aromatase enzyme and neuroestrogen synthesis. In a previous study performed in male sea bass, we reported that Gnih inhibited the reproductive axis by acting at the three levels of the brain-pituitary-gonad axis. Moreover, the presence of Gnih cells and fibers in the telencephalon, mesencephalon and rhombencephalon suggests a role of Gnih in regulating other important brain functions in sea bass, including behavior. In this study, we have analyzed the effects of the intracerebroventricular (icv) injection of sbGnih-2 on the brain and pituitary expression of the main neurosteroids-synthesizing enzymes (stAR, cyp17, 3β-hsd, 17β-hsd, cyp19b, cyp7b), as well as on estrogen and androgen receptors (erα, erβ1, erβ2, ar). A combination of immunohistochemistry and in situ hybridization was also used to identify putative interaction of Gnih- and aromatase-positive cells. We also performed a mirror test study as a proxy to measure aggression levels and agonistic behavior after icv injection of sbGnih-2. Central administration of sbGnih-2 at different doses reduced the transcript levels of 3β-hsd and 17β-hsd, and increased the expression of cyp19b (brain aromatase) in the sea bass brain. Neuroanatomical results suggest that paracrine and neuroendocrine actions could mediate Gnih effects on aromatase expression. Central administration of sbGnih-2 also decreased the pituitary expression of 17β-hsd and estrogen receptors (erβ2). The mirror test analysis showed that sbGnih-2 affected the agonistic/aggressive behavior of sea bass as revealed by the decreased interaction with the mirror, lower time spent in the mirror zone, increased latency to establish contact with the mirror and higher mean distance to the mirror zone. In contrast, locomotor activity parameters measured were not affected by sbGnih-2 injection. Taken together, our results showed for the first time in fish that Gnih inhibits social-aggressive behavior and affects the gene expression of neurosteroid-synthesizing enzymes giving rise to neuroandrogens and neuroestrogens in the sea bass brain.

Mirror self-recognition in ghost crab (Ocypode quadrata).

Mirror self-recognition has been examined primarily in vertebrate species, largely through the use of a mirror mark test. Recently, however, there has been growing interest in the notion that all animals likely need some form of self-representation to successfully interact with their environment (Kohda et al. in Plos Biol https://doi.org/10.1371/journal.pbio.3001529 , 2022; de Waal in Plos Biol https://doi.org/10.1371/journal.pbio.3000112 , 2019). Our knowledge of this trait in invertebrate species is particularly limited, while there are several species potentially well suited for mirror mark tests. To better understand this trait and its distribution, the current research examines mirror self-recognition in ghost crab (Ocypode quadrata) using a visual mirror mark test. In an initial phase, animals were exposed to a flat oriented mirror for an extended period. In a subsequent testing phase, subjects were either (1) marked (green sticker) or sham marked (clear sticker) and exposed to a mirror, (2) marked and placed in a tank without a mirror, or (3) marked and shown video of a marked conspecific. Results showed that marked, relative to sham marked, animals were significantly more likely to remove marks when exposed to mirrors. Findings also suggests this behavior was not driven by the perception of mirror images as conspecifics, or issues related to mark placement. These data are interpreted in support of a rudimentary form of self-awareness in this species. Discussions highlight potential cognitive mechanisms that facilitate this type of self-representation and the need for additional research that informs about more sophisticated forms of self-awareness.

Random vibration testing of microelectromechanical deformable mirrors for space-based high-contrast imaging

Space-based stellar coronagraph instruments aim to directly image exoplanets that are a fraction of an arcsecond separated from and 10 billion times fainter than their host star. To achieve this, one or more deformable mirrors (DMs) are used in concert with coronagraph masks to control the wavefront and minimize diffracted starlight in a region of the image known as the “dark zone” or “dark hole (DH).” The DMs must have a high number of actuators (50 to 96 across) to allow for DHs that are large enough to image a range of desired exoplanet separations. In addition, the surfaces of the DMs must be controlled at the picometer level to enable the required contrast. Any defect in the mechanical structure of the DMs or electronic system could significantly impact the scientific potential of the mission. Thus NASA’s Exoplanet Exploration Program procured two 50 × 50 microelectromechanical DMs manufactured by Boston Micromachines Corporation to test their robustness to the vibrational environment that the DMs will be exposed to during launch. The DMs were subjected to a battery of functional and high-contrast imaging tests before and after exposure to flight-like random vibrations. The DMs did not show any significant functional nor performance degradation at 10 − 8 contrast levels.

Revisiting the mark test for mirror self-recognition.

Despite half a century of research, few species have exhibited convincing evidence of mirror self-recognition. Several methodological objections to Gallup's mark test have been raised, but empirical studies have shown that methodology does not adequately explain why most species fail to recognize themselves in mirrors. However, a potential issue was constantly overlooked: mirror ecological relevance. Although reflective surfaces in nature are horizontal, previous studies indeed used vertical mirrors. The present study revisited the mark test to address this issue in an experiment with capuchin monkeys (Sapajus apella). Additionally, a new procedure based on sticker exchange was designed to maximize mark attractiveness. Subjects were first trained to exchange stickers, habituated to being head-touched, and exposed to a horizontal mirror. Then, their mirror self-recognition was tested by surreptitiously placing a sticker on their forehead before requesting them to exchange stickers. None of the monkeys removed the sticker from their forehead in the presence of the mirror. In line with previous studies, this result suggests that capuchin monkeys lack the ability to recognize themselves in mirrors. Nonetheless, this modified mark test could prove useful in future studies, including investigation of interindividual variability of mirror self-recognition in self-recognizing species.

Effects of environmental concentrations of caffeine on adult zebrafish behaviour: a short-term exposure scenario

Caffeine (CAF) has been considered an emerging environmental contaminant and its presence indicator of anthropogenic contamination. This study evaluated the effects of environmental concentrations of CAF (0, 0.5, 1.5, and 300 μg. L−1) on the behaviour of adult zebrafish (Danio rerio) after 7 days of exposure. The components of feeding, locomotion, boldness (new tank test), sociability (schooling test), and aggression (mirror test) were analysed. Growth rate and weight were investigated as complementary measures. CAF (0.5, 1.5, and 300 μg. L−1) reduced exploratory behaviour in zebrafish, increased feeding latency time (1.5, and 300 μg. L−1), and decreased growth rate and fish weight (300 μg. L−1). CAF also induced aggressive behaviour (0.5, 1.5, and 300 μg. L−1) and decreased appetence to the shoal (sociability) (0.5, and 1.5 μg. L−1). This study showed that low doses of CAF can induce behavioural effects in zebrafish that may have significant long-term impacts on vital ecological functions.

The Infinity Mirror Test for Graph Models

Graph models, like other machine learning models, have implicit and explicit biases built-in, which often impact performance in nontrivial ways. The model's faithfulness is often measured by comparing the newly generated graph against the source graph using any number or combination of graph properties. Differences in the size or topology of the generated graph, therefore, indicate a loss in the model. Yet, in many systems, errors encoded in loss functions are subtle and not well understood. In the present work, we introduce the Infinity Mirror test for analyzing the robustness of graph models. This straightforward stress test works by repeatedly fitting a model to its own outputs. A hypothetically perfect graph model would have no deviation from the source graph; however, the model's implicit biases and assumptions are exaggerated by the Infinity Mirror test, exposing potential issues that were previously obscured. Through an analysis of thousands of experiments on synthetic and real-world graphs, we show that several conventional graph models degenerate in exciting and informative ways. We believe that the observed degenerative patterns are clues to the future development of better graph models.

The white-browed laughingthrush (Pterorhinus sannio) did not pass the mirror self-recognition test

Self-awareness is an important concept in discussions of consciousness that has received increasing attention. To our knowledge, mirror self-recognition and self-awareness has not been studied in the white-browed laughing thrush Pterorhinus sannio. In our investigation, wild Pterorhinus sannio were presented with a self-recognition test known as the mirror self-recognition test (MSR). All birds performed four different displays in front of the mirror that we call “look around”, “crouch”, “jump to top of the mirror”, and “shake the wings”. These behaviours did not occur in the absence of the mirror. These behaviours typically are directed towards other individuals this suggest that P. sannio does not recognise itself in the mirror, and it does not have the capacity of self-awareness, at least not judged from the mark mirror test.

Fluid Intake and the Occurrence of Erosive Tooth Wear in a Group of Healthy and Disabled Children from the Małopolska Region (Poland).

Background: The aim of this study was to analyse the relationship between the type and amount of fluid intake and the incidence of erosive tooth wear in a group of healthy children and children with disabilities. Methods: This study was conducted among children aged 6-17 years, patients of the Dental Clinic in Kraków. The research included 86 children: 44 healthy children and 42 children with disabilities. The prevalence of erosive tooth wear using the Basic Erosive Wear Examination (BEWE) index was assessed by the dentist, who also determined the prevalence of dry mouth using a mirror test. A qualitative-quantitative questionnaire on the frequency of consumption of specific liquids and foods related to the occurrence of erosive tooth wear, completed by the children's parents, was used to assess dietary habits. Results: The occurrence of erosive tooth wear was determined for 26% of the total number of children studied, and these were mostly lesions of minor severity. The mean value of the sum of the BEWE index was significantly higher (p = 0.0003) in the group of children with disabilities. In contrast, the risk of erosive tooth wear was non-significantly higher in children with disabilities (31.0%) than in healthy children (20.5%). Dry mouth was significantly more frequently identified among children with disabilities (57.1%). Erosive tooth wear was also significantly more common (p = 0.02) in children whose parents declared the presence of eating disorders. Children with disabilities consumed flavoured water or water with added syrup/juice and fruit teas with significantly higher frequency, while there were no differences in quantitative fluid intake between groups. The frequency and quantity of drinking flavoured waters or water with added syrup/juice, sweetened carbonated, and non-carbonated drinks were associated with the occurrence of erosive tooth wear for all children studied. Conclusions: The group of studied children presents inappropriate drinking behaviours regarding the frequency and amount of beverages consumed, which, especially in a group of children with disabilities, may contribute to the formation of erosive cavities.