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Astrobiology May 2024Assessing the past habitability of Mars and searching for evidence of ancient life at Jezero crater via the rover are the key objectives of NASA's Mars 2020 mission....
Investigating Microbial Biosignatures in Aeolian Environments Using Micro-X-Ray: Simulation of PIXL Instrument Analyses at Jezero Crater Onboard the Perseverance Mars 2020 Rover.
Assessing the past habitability of Mars and searching for evidence of ancient life at Jezero crater via the rover are the key objectives of NASA's Mars 2020 mission. Onboard the rover, PIXL (Planetary Instrument for X-ray Lithochemistry) is one of the best suited instruments to search for microbial biosignatures due to its ability to characterize chemical composition of fine scale textures in geological targets using a nondestructive technique. PIXL is also the first micro-X-ray fluorescence (XRF) spectrometer onboard a Mars rover. Here, we present guidelines for identifying and investigating a microbial biosignature in an aeolian environment using PIXL-analogous micro-XRF (μXRF) analyses. We collected samples from a modern wet aeolian environment at Padre Island, Texas, that contain buried microbial mats, and we analyzed them using μXRF techniques analogous to how PIXL is being operated on Mars. We show via μXRF technique and microscope images the geochemical and textural variations from the surface to ∼40 cm depth. Microbial mats are associated with heavy-mineral lags and show specific textural and geochemical characteristics that make them a distinct biosignature for this environment. Upon burial, they acquire a diffuse texture due to the expansion and contraction of gas-filled voids, and they present a geochemical signature rich in iron and titanium, which is due to the trapping of heavy minerals. We show that these intrinsic characteristics can be detected via μXRF analyses, and that they are distinct from buried abiotic facies such as cross-stratification and adhesion ripple laminations. We also designed and conducted an interactive survey using the Padre Island μXRF data to explore how different users chose to investigate a biosignature-bearing dataset via PIXL-like sampling strategies. We show that investigating biosignatures via PIXL-like analyses is heavily influenced by technical constraints ( the XRF measurement characteristics) and by the variety of approaches chosen by different scientists. Lessons learned for accurately identifying and characterizing this biosignature in the context of rover-mission constraints include defining relative priorities among measurements, favoring a multidisciplinary approach to the decision-making process of XRF measurements selection, and considering abiotic results to support or discard a biosignature interpretation. Our results provide guidelines for PIXL analyses of potential biosignature on Mars.
Topics: Mars; Exobiology; Extraterrestrial Environment; Spectrometry, X-Ray Emission
PubMed: 38768431
DOI: 10.1089/ast.2022.0031 -
Astrobiology May 2024Pigments serve a multitude of functions in biology including light harvesting for photosynthesis, radiation protection, membrane support, and defense. The ubiquity of...
Pigments serve a multitude of functions in biology including light harvesting for photosynthesis, radiation protection, membrane support, and defense. The ubiquity of pigments-especially within extremophiles found in high-radiation, high-salinity, and dry environments-and their detectability via mission-ready techniques have elevated these molecules as promising targets in the search for evidence of life elsewhere. Moreover, the detection of pigments has been proposed as a "smoking gun" for extraterrestrial life as it has been suggested that these molecules cannot be generated abiotically. However, while pigments may hold promise as a biosignature, current understanding of their possible prebiotic origins remains understudied and uncertain. Better understanding of the abiotic synthesis of pigments is critical for evaluating the biogenicity of any pigment detected during missions, including by the Mars Perseverance rover or from returned samples. Compounding this uncertainty is the broad definition of pigment as it includes any compound capable of absorbing visible light and by itself does not specify a particular chemical motif. While not experimentally verified, there are promising prebiotic routes for generating pigments including hemes, chlorophylls, and carotenoids. Herein, we review the biochemistry of pigments, the inherent assumptions made when searching for these molecules in the field, their abiotic synthesis in industry and prebiotic reactions, prebiotically relevant molecules that can mimic their spectral signatures, and implications/recommendations for future work.
PubMed: 38768415
DOI: 10.1089/ast.2023.0006 -
BioRxiv : the Preprint Server For... May 2024Extinction learning is an essential form of cognitive flexibility, which enables obsolete reward associations to be discarded. Its downregulation can lead to...
Extinction learning is an essential form of cognitive flexibility, which enables obsolete reward associations to be discarded. Its downregulation can lead to perseveration, a symptom seen in several neuropsychiatric disorders. This balance is regulated by dopamine from VTA (ventral tegmental area dopamine) neurons, which in turn are largely controlled by GABA (gamma amino-butyric acid) synapses. However, the causal relationship of these circuit elements to extinction and perseveration remain incompletely understood. Here, we employ an innovative drug-targeting technology, DART (drug acutely restricted by tethering), to selectively block GABA receptors on VTA neurons as mice engage in Pavlovian learning. DART eliminated GABA -mediated pauses-brief decrements in VTA activity canonically thought to drive extinction learning. However, contrary to the hypothesis that blocking VTA pauses should eliminate extinction learning, we observed the opposite-accelerated extinction learning. Specifically, DART eliminated the naturally occurring perseveration seen in half of control mice. We saw no impact on Pavlovian conditioning, nor on other aspects of VTA neural firing. These findings challenge canonical theories, recasting GABA -mediated VTA pauses from presumed facilitators of extinction to drivers of perseveration. More broadly, this study showcases the merits of targeted synaptic pharmacology, while hinting at circuit interventions for pathological perseveration.
PubMed: 38766037
DOI: 10.1101/2024.05.09.593320 -
Scientific Reports May 2024Planetary exploration relies considerably on mineral characterization to advance our understanding of the solar system, the planets and their evolution. Thus, we must...
Planetary exploration relies considerably on mineral characterization to advance our understanding of the solar system, the planets and their evolution. Thus, we must understand past and present processes that can alter materials exposed on the surface, affecting space mission data. Here, we analyze the first dataset monitoring the evolution of a known mineral target in situ on the Martian surface, brought there as a SuperCam calibration target onboard the Perseverance rover. We used Raman spectroscopy to monitor the crystalline state of a synthetic apatite sample over the first 950 Martian days (sols) of the Mars2020 mission. We note significant variations in the Raman spectra acquired on this target, specifically a decrease in the relative contribution of the Raman signal to the total signal. These observations are consistent with the results of a UV-irradiation test performed in the laboratory under conditions mimicking ambient Martian conditions. We conclude that the observed evolution reflects an alteration of the material, specifically the creation of electronic defects, due to its exposure to the Martian environment and, in particular, UV irradiation. This ongoing process of alteration of the Martian surface needs to be taken into account for mineralogical space mission data analysis.
PubMed: 38760365
DOI: 10.1038/s41598-024-61494-5 -
Journal of Gambling Studies May 2024Desire thinking, within the metacognitive model of addictive behaviors, is conceptualized as a transdiagnostic process linked to the escalation and maintenance of...
Desire thinking, within the metacognitive model of addictive behaviors, is conceptualized as a transdiagnostic process linked to the escalation and maintenance of craving for various addictive disorders; however, its application to the understanding of gambling and the Chinese community remains at an early stage. The present study aimed to introduce desire thinking into gambling research in the Chinese context by: (1) testing the applicability of its two-factor conceptualization and assessment tool, the Desire Thinking Questionnaire (DTQ), and (2) exploring its association with dysregulated and regulated engagements in gambling (i.e., Gambling Disorder [GD] and responsible gambling [RG], respectively). We conducted a telephone survey in Macao, China, and obtained a probability sample of 837 Chinese adult past-year gamblers (48.5% men; age: M = 41.11, SD = 14.31) with a two-stage cluster random sampling method. Our data indicated the psychometric adequacy of the two-factor DTQ (i.e., verbal perseveration and imaginal prefiguration) for measuring Chinese gamblers' desire thinking about gambling. After controlling for craving and demographics, desire thinking contributed to an additional 12.1% and 18.9% variance explained in GD tendency and RG behaviors, respectively. This study provides the first empirical evidence of the utility of desire thinking and the DTQ in facilitating gambling research on Chinese gamblers. Our findings also suggest the value of incorporating desire thinking in detecting and treating GD and in promoting RG.
PubMed: 38758351
DOI: 10.1007/s10899-024-10313-7 -
Frontiers in Psychology 2024Learning, an important activity for both human and animals, has long been a focal point of research. During the learning process, subjects assimilate not only their own...
Learning, an important activity for both human and animals, has long been a focal point of research. During the learning process, subjects assimilate not only their own information but also information from others, a phenomenon known as social learning. While numerous studies have explored the impact of social feedback as a reward/punishment during learning, few studies have investigated whether social feedback facilitates or inhibits the learning of environmental rewards/punishments. This study aims to test the effects of social feedback on economic feedback and its cognitive processes by using the Iowa Gambling Task (IGT). One hundred ninety-two participants were recruited and categorized into one non-social feedback group and four social feedback groups. Participants in the social feedback groups were informed that after the outcome of each choice, they would also receive feedback from an online peer. This peer was a fictitious entity, with variations in identity (novice or expert) and feedback type (random or effective). The Outcome-Representation Learning model (ORL model) was used to quantify the cognitive components of learning. Behavioral results showed that both the identity of the peer and the type of feedback provided significantly influenced the deck selection, with effective social feedback increasing the ratio of chosen good decks. Results in the ORL model showed that the four social feedback groups exhibited lower learning rates for gain and loss compared to the nonsocial feedback group, which suggested, in the social feedback groups, the impact of the recent outcome on the update of value decreased. Parameters such as forgetfulness, win frequency, and deck perseverance in the expert-effective feedback group were significantly higher than those in the non-social feedback and expert-random feedback groups. These findings suggest that individuals proactively evaluate feedback providers and selectively adopt effective feedback to enhance learning.
PubMed: 38756493
DOI: 10.3389/fpsyg.2024.1292808 -
Science (New York, N.Y.) May 2024"Heroic network" forges ahead as gang violence dominates life and landscape.
"Heroic network" forges ahead as gang violence dominates life and landscape.
Topics: Humans; Biomedical Research; Haiti; Research Personnel; Violence; Social Networking
PubMed: 38753774
DOI: 10.1126/science.adq4548 -
Frontiers in Psychology 2024The global dissemination of Chinese martial arts (CMAs), transcends mere physical activity; it represents a cultural and philosophical journey that contributes to...
BACKGROUND
The global dissemination of Chinese martial arts (CMAs), transcends mere physical activity; it represents a cultural and philosophical journey that contributes to enhanced psychological well-being. Capturing international attention, CMAs have engendered a network of global instructors committed to their cross-cultural teaching. However, the narrative of CMAs across the globe is incomplete without understanding the psychological factors that fuel the perseverance of these international instructors. Their relentless commitment, motivated by factors beyond the cultural and geographical barriers, poses a unique question: What motivates these instructors to persist in teaching CMAs in the face of such challenges? The study aims to uncover the key motivational mechanisms that influence the perseverance of international CMAs instructors in their teaching endeavors.
METHODS
Employing Self-Determination Theory, 147 international CMAs instructors completed the Motivation for Teaching CMAs Scale, Perceived Belonging Scale, and Perseverance in Teaching CMAs Scale. SPSS 20.0 was utilized for conducting descriptive statistics, common method bias tests, and correlation analyses. Structural equation modeling was performed using AMOS 26.0.
RESULTS
Autonomous Motivation positively affected perseverance in teaching CMAs ( = 0.369, = 0.465, = 4.232, < 0.001). In contrast, Amotivation negatively affected perseverance ( = -0.323, = -0.382, = -3.561, < 0.001). Neither Controlled Motivation nor Sense of Belonging significantly affected perseverance. The model explained 27.9% of the variance in perseverance, offering insights into the motivational mechanisms influencing international CMAs instructors.
CONCLUSION
This study concludes that the perseverance of international instructors in teaching CMAs is primarily driven by overcoming amotivation and fostering autonomous motivation, rather than short-term internal or external incentives, which appear ineffective. Additionally, sense of belonging to their CMA school does not significantly influence their perseverance, potentially due to the diverse cultural backgrounds of the instructors surveyed. The findings suggest that by enhancing the recognition and acceptance of CMAs' core philosophies and values, aligning teaching practices with personal and cultural values, and fostering a profound passion for CMAs, international instructors could boost their autonomous motivation, which is crucial for their sustained commitment in promoting CMAs globally.
PubMed: 38746923
DOI: 10.3389/fpsyg.2024.1391207 -
Surgical Neurology International 2024Resection of bilateral parasagittal meningiomas of the dominant cortex is challenging. Some postoperative consequences are difficult to predict due to their low...
BACKGROUND
Resection of bilateral parasagittal meningiomas of the dominant cortex is challenging. Some postoperative consequences are difficult to predict due to their low incidence. However, it is essential to recognize reversible symptoms. Akinetic mutism is a devastating but reversible symptom that occurs after supplementary motor area (SMA) injury. This report aims to provide more information to support the clinical progression of this syndrome.
CASE DESCRIPTION
A 47-year-old woman presented with psychomotor retardation and subtle weakness, particularly on the left side. A palpable mass was identified at the head vertex. Magnetic resonance imaging revealed bilateral parasagittal meningiomas with bone and sinus invasion of the SMA. A craniotomy was performed to remove the intracapsular tumor. Two days after the operation, the patient developed gradual deterioration in her motor function until it became a lock-in-like syndrome. Then, 1.5 months after treatment in the hospital and rehabilitation unit, she gradually improved her motor, cognitive, and psychomotor skills. Total recovery was achieved after 1 year.
CONCLUSION
Surgery for lesions involving bilateral SMA can cause akinetic mutism. The typical manifestation of this syndrome may be devastating. However, it is reversible, and patients can regain full motor and cognitive functions over time without specific treatments. It is crucial to persevere and continue to provide the best care to the patient until recovery.
PubMed: 38742016
DOI: 10.25259/SNI_130_2024 -
Memory & Cognition May 2024Models of recognition memory often assume that decisions are made independently from each other. Yet there is growing evidence that consecutive recognition responses...
Models of recognition memory often assume that decisions are made independently from each other. Yet there is growing evidence that consecutive recognition responses show sequential dependencies, whereby making one response increases the probability of repeating that response from one trial to the next trial. Across six experiments, we replicated this response-related carryover effect using word and nonword stimuli and further demonstrated that the content of the previous trial-both perceptual and conceptual-can also bias the response to the current test probe, with both perceptual (orthographic) and conceptual (semantic) similarity boosting the probability of consecutive "old" responses. Finally, a manipulation of attentional engagement in Experiments 3a and 3b provided little evidence these carryover effects on recognition decisions are merely a product of lapses in attention. Taken together, the current study reinforces prior findings that recognition decisions are not made independently, and that multiple forms of information perseverate across consecutive trials.
PubMed: 38724882
DOI: 10.3758/s13421-024-01582-z