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PNAS Nexus
Number of Followers: 9  Open Access journalISSN (Online) 2752-6542 Published by Oxford University Press  [425 journals]
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- A semiconducting hybrid of RhOx/GaN@InGaN for simultaneous activation of
methane and water toward syngas by photocatalysis
First page: pgad347
Abstract: AbstractPrior to the eventual arrival of carbon neutrality, solar-driven syngas production from methane steam reforming presents a promising approach to produce transportation fuels and chemicals. Simultaneous activation of the two reactants, i.e. methane and water, with notable geometric and polar discrepancy is at the crux of this important subject yet greatly challenging. This work explores an exceptional semiconducting hybrid of RhOx/GaN@InGaN nanowires for overcoming this critical challenge to achieve efficient syngas generation from methane steam reforming by photocatalysis. By coordinating density functional theoretical calculations and microscopic characterizations, with in situ spectroscopic measurements, it is found that the multifunctional RhOx/GaN interface is effective for simultaneously activating both CH4 and H2O by stretching the C–H and O–H bonds because of its unique Lewis acid/base attribute. With the aid of energetic charge carriers, the stretched C–H and O–H bonds of reactants are favorably cleaved, resulting in the key intermediates, i.e. *CH3, *OH, and *H, to sit on Rh sites, Rh sites, and N sites, respectively. Syngas is subsequently produced via energetically favored pathway without additional energy inputs except for light. As a result, a benchmarking syngas formation rate of 8.1 mol·gcat−1·h−1 is achieved with varied H2/CO ratios from 2.4 to 0.8 under concentrated light illumination of 6.3 W·cm−2, enabling the achievement of a superior turnover number of 10,493 mol syngas per mol Rh species over 300 min of long-term operation. This work presents a promising strategy for green syngas production from methane steam reforming by utilizing unlimited solar energy.
PubDate: Tue, 21 Nov 2023 00:00:00 GMT
DOI: 10.1093/pnasnexus/pgad347
Issue No: Vol. 2, No. 11 (2023)
- Near-term investments in forest management support long-term carbon
sequestration capacity in forests of the United States
First page: pgad345
Abstract: AbstractThe forest carbon sink of the United States offsets emissions in other sectors. Recently passed US laws include important climate legislation for wildfire reduction, forest restoration, and forest planting. In this study, we examine how wildfire reduction strategies and planting might alter the forest carbon sink. Our results suggest that wildfire reduction strategies reduce carbon sequestration potential in the near term but provide a longer term benefit. Planting initiatives increase carbon sequestration but at levels that do not offset lost sequestration from wildfire reduction strategies. We conclude that recent legislation may increase near-term carbon emissions due to fuel treatments and reduced wildfire frequency and intensity, and expand long-term US carbon sink strength.
PubDate: Tue, 21 Nov 2023 00:00:00 GMT
DOI: 10.1093/pnasnexus/pgad345
Issue No: Vol. 2, No. 11 (2023)
- Gender stereotypes embedded in natural language are stronger in more
economically developed and individualistic countries
First page: pgad355
Abstract: AbstractGender stereotypes contribute to gender imbalances, and analyzing their variations across countries is important for understanding and mitigating gender inequalities. However, measuring stereotypes is difficult, particularly in a cross-cultural context. Word embeddings are a recent useful tool in natural language processing permitting to measure the collective gender stereotypes embedded in a society. In this work, we used word embedding models pre-trained on large text corpora from more than 70 different countries to examine how gender stereotypes vary across countries. We considered stereotypes associating men with career and women with family as well as those associating men with math or science and women with arts or liberal arts. Relying on two different sources (Wikipedia and Common Crawl), we found that these gender stereotypes are all significantly more pronounced in the text corpora of more economically developed and more individualistic countries. Our analysis suggests that more economically developed countries, while being more gender equal along several dimensions, also have stronger gender stereotypes. Public policy aiming at mitigating gender imbalances in these countries should take this feature into account. Besides, our analysis sheds light on the “gender equality paradox,” i.e. on the fact that gender imbalances in a large number of domains are paradoxically stronger in more developed/gender equal/individualistic countries.
PubDate: Tue, 21 Nov 2023 00:00:00 GMT
DOI: 10.1093/pnasnexus/pgad355
Issue No: Vol. 2, No. 11 (2023)
- Photovoltaic fields largely outperform afforestation efficiency in global
climate change mitigation strategies
First page: pgad352
Abstract: AbstractSuppression of carbon emissions through photovoltaic (PV) energy and carbon sequestration through afforestation provides complementary climate change mitigation (CCM) strategies. However, a quantification of the “break-even time” (BET) required to offset the warming impacts of the reduced surface reflectivity of incoming solar radiation (albedo effect) is needed, though seldom accounted for in CCM strategies. Here, we quantify the CCM potential of PV fields and afforestation, considering atmospheric carbon reductions, solar panel life cycle analysis (LCA), surface energy balance, and land area required across different climatic zones, with a focus on drylands, which offer the main remaining land area reserves for forestation aiming climate change mitigation (Rohatyn S, Yakir D, Rotenberg E, Carmel Y. Limited climate change mitigation potential through forestation of the vast dryland regions. 2022. Science 377:1436–1439). Results indicate a BET of PV fields of ∼2.5 years but >50× longer for dryland afforestation, even though the latter is more efficient at surface heat dissipation and local surface cooling. Furthermore, PV is ∼100× more efficient in atmospheric carbon mitigation. While the relative efficiency of afforestation compared with PV fields significantly increases in more mesic climates, PV field BET is still ∼20× faster than in afforestation, and land area required greatly exceeds availability for tree planting in a sufficient scale. Although this analysis focusing purely on the climatic radiative forcing perspective quantified an unambiguous advantage for the PV strategy over afforestation, both approaches must be combined and complementary, depending on climate zone, since forests provide crucial ecosystem, climate regulation, and even social services.
PubDate: Tue, 21 Nov 2023 00:00:00 GMT
DOI: 10.1093/pnasnexus/pgad352
Issue No: Vol. 2, No. 11 (2023)
- Correction to: A kirigami-enabled electrochromic wearable
variable-emittance device for energy-efficient adaptive personal
thermoregulation
First page: pgad378
Abstract: This is a correction to: Ting-Hsuan Chen, Yaoye Hong, Ching-Tai Fu, Ankita Nandi, Wanrong Xie, Jie Yin, Po-Chun Hsu, A kirigami-enabled electrochromic wearable variable-emittance device for energy-efficient adaptive personal thermoregulation, PNAS Nexus, Volume 2, Issue 6, June 2023, pgad165, https://doi.org/10.1093/pnasnexus/pgad165
PubDate: Wed, 15 Nov 2023 00:00:00 GMT
DOI: 10.1093/pnasnexus/pgad378
Issue No: Vol. 2, No. 11 (2023)
- Correction to: Humans feel too special for machines to score their morals
First page: pgad379
Abstract: This is a correction to: Zoe A Purcell, Jean-François Bonnefon, Humans feel too special for machines to score their morals, PNAS Nexus, Volume 2, Issue 6, June 2023, pgad179, https://doi.org/10.1093/pnasnexus/pgad179
PubDate: Wed, 15 Nov 2023 00:00:00 GMT
DOI: 10.1093/pnasnexus/pgad379
Issue No: Vol. 2, No. 11 (2023)
- Correction to: Online reading habits can reveal personality traits:
towards detecting psychological microtargeting
First page: pgad380
Abstract: This is a correction to: Almog Simchon, Adam Sutton, Matthew Edwards, Stephan Lewandowsky, Online reading habits can reveal personality traits: towards detecting psychological microtargeting, PNAS Nexus, Volume 2, Issue 6, June 2023, pgad191, https://doi.org/10.1093/pnasnexus/pgad191
PubDate: Wed, 15 Nov 2023 00:00:00 GMT
DOI: 10.1093/pnasnexus/pgad380
Issue No: Vol. 2, No. 11 (2023)
- Correction to: How membership in the North Atlantic Treaty Organization
transforms public support for war
First page: pgad381
Abstract: This is a correction to: Michael Tomz, Jessica L P Weeks, Kirk Bansak, How membership in the North Atlantic Treaty Organization transforms public support for war, PNAS Nexus, Volume 2, Issue 7, July 2023, pgad206, https://doi.org/10.1093/pnasnexus/pgad206
PubDate: Wed, 15 Nov 2023 00:00:00 GMT
DOI: 10.1093/pnasnexus/pgad381
Issue No: Vol. 2, No. 11 (2023)
- Correction to: Three-dimensional printing of patient-specific computed
tomography lung phantoms: a reader study
First page: pgad369
Abstract: This is a correction to: Nadav Shapira, Kevin Donovan, Kai Mei, Michael Geagan, Leonid Roshkovan, Grace J Gang, Mohammed Abed, Nathaniel B Linna, Coulter P Cranston, Cathal N O'Leary, Ali H Dhanaliwala, Despina Kontos, Harold I Litt, J Webster Stayman, Russell T Shinohara, Peter B Noël, Three-dimensional printing of patient-specific computed tomography lung phantoms: a reader study, PNAS Nexus, Volume 2, Issue 3, March 2023, pgad026, https://doi.org/10.1093/pnasnexus/pgad026
PubDate: Wed, 15 Nov 2023 00:00:00 GMT
DOI: 10.1093/pnasnexus/pgad369
Issue No: Vol. 2, No. 11 (2023)
- Correction to: Development of a rapid and ultra-sensitive RNA:DNA hybrid
immunocapture based biosensor for visual detection of SARS-CoV-2 RNA
First page: pgad370
Abstract: This is a correction to: Anusree Dey, Jyoti Prakash, Rituparna Das, Sandeep Shelar, Ajay Saini, Susan Cherian, Sofia C Patel, Puthusserickal A Hassan, Ashwini Khandekar, Kinshuk Dasgupta, Hari Sharan Misra, Sheetal Uppal, Development of a rapid and ultra-sensitive RNA:DNA hybrid immunocapture based biosensor for visual detection of SARS-CoV-2 RNA, PNAS Nexus, Volume 2, Issue 3, March 2023, pgad031, https://doi.org/10.1093/pnasnexus/pgad031
PubDate: Wed, 15 Nov 2023 00:00:00 GMT
DOI: 10.1093/pnasnexus/pgad370
Issue No: Vol. 2, No. 11 (2023)
- Correction to: Digital spatial profiling of human parathyroid tumors
First page: pgad371
Abstract: This is a correction to: Chia-Ling Tu, Wenhan Chang, Julie A Sosa, James Koh, Digital spatial profiling of human parathyroid tumors reveals cellular and molecular alterations linked to vitamin D deficiency, PNAS Nexus, Volume 2, Issue 3, March 2023, pgad073, https://doi.org/10.1093/pnasnexus/pgad073
PubDate: Wed, 15 Nov 2023 00:00:00 GMT
DOI: 10.1093/pnasnexus/pgad371
Issue No: Vol. 2, No. 11 (2023)
- Correction to: Acinetobacter baumannii adaptation to the host pH
microenvironment is mediated by allelic variation in a single residue of
BauA protein
First page: pgad372
Abstract: This is a correction to: Tao Li, Deyan Luo, Nianzhi Ning, Xiong Liu, Fanghong Chen, Liangyan Zhang, Chunmei Bao, Zhan Li, Deyu Li, Hongjing Gu, Fen Qu, Xiaolan Yang, Yanyu Huang, Boan Li, Hui Wang, Acinetobacter baumannii adaptation to the host pH microenvironment is mediated by allelic variation in a single residue of BauA protein, PNAS Nexus, Volume 2, Issue 4, April 2023, pgad079, https://doi.org/10.1093/pnasnexus/pgad079
PubDate: Wed, 15 Nov 2023 00:00:00 GMT
DOI: 10.1093/pnasnexus/pgad372
Issue No: Vol. 2, No. 11 (2023)
- Correction to: A complementary approach for genetic diagnosis of inborn
errors of immunity using proteogenomic analysis
First page: pgad373
Abstract: This is a correction to: Fumiaki Sakura, Kosuke Noma, Takaki Asano, Kay Tanita, Etsushi Toyofuku, Kentaro Kato, Miyuki Tsumura, Hiroshi Nihira, Kazushi Izawa, Kanako Mitsui-Sekinaka, Ryo Konno, Yusuke Kawashima, Yoko Mizoguchi, Shuhei Karakawa, Seiichi Hayakawa, Hiroshi Kawaguchi, Kohsuke Imai, Shigeaki Nonoyama, Takahiro Yasumi, Hidenori Ohnishi, Hirokazu Kanegane, Osamu Ohara, Satoshi Okada, A complementary approach for genetic diagnosis of inborn errors of immunity using proteogenomic analysis, PNAS Nexus, Volume 2, Issue 4, April 2023, pgad104, https://doi.org/10.1093/pnasnexus/pgad104
PubDate: Wed, 15 Nov 2023 00:00:00 GMT
DOI: 10.1093/pnasnexus/pgad373
Issue No: Vol. 2, No. 11 (2023)
- Correction to: mHealth hyperspectral learning for instantaneous
spatiospectral imaging of hemodynamics
First page: pgad374
Abstract: This is a correction to: Yuhyun Ji, Sang Mok Park, Semin Kwon, Jung Woo Leem, Vidhya Vijayakrishnan Nair, Yunjie Tong, Young L Kim, mHealth hyperspectral learning for instantaneous spatiospectral imaging of hemodynamics, PNAS Nexus, Volume 2, Issue 4, April 2023, pgad111, https://doi.org/10.1093/pnasnexus/pgad111
PubDate: Wed, 15 Nov 2023 00:00:00 GMT
DOI: 10.1093/pnasnexus/pgad374
Issue No: Vol. 2, No. 11 (2023)
- Correction to: Student close contact behavior and COVID-19 transmission in
China's classrooms
First page: pgad375
Abstract: This is a correction to: Yong Guo, Zhiyang Dou, Nan Zhang, Xiyue Liu, Boni Su, Yuguo Li, Yinping Zhang, Student close contact behavior and COVID-19 transmission in China's classrooms, PNAS Nexus, Volume 2, Issue 5, May 2023, pgad142, https://doi.org/10.1093/pnasnexus/pgad142
PubDate: Wed, 15 Nov 2023 00:00:00 GMT
DOI: 10.1093/pnasnexus/pgad375
Issue No: Vol. 2, No. 11 (2023)
- Correction to: Media use and vaccine resistance
First page: pgad376
Abstract: This is a correction to: Jon Green, James N Druckman, Matthew A Baum, Katherine Ognyanova, Matthew D Simonson, Roy H Perlis, David Lazer, Media use and vaccine resistance, PNAS Nexus, Volume 2, Issue 5, May 2023, pgad146, https://doi.org/10.1093/pnasnexus/pgad146
PubDate: Wed, 15 Nov 2023 00:00:00 GMT
DOI: 10.1093/pnasnexus/pgad376
Issue No: Vol. 2, No. 11 (2023)
- Correction to: Explaining human interactions on the road by large-scale
integration of computational psychological theory
First page: pgad377
Abstract: This is a correction to: Gustav Markkula, Yi-Shin Lin, Aravinda Ramakrishnan Srinivasan, Jac Billington, Matteo Leonetti, Amir Hossein Kalantari, Yue Yang, Yee Mun Lee, Ruth Madigan, Natasha Merat, Explaining human interactions on the road by large-scale integration of computational psychological theory, PNAS Nexus, Volume 2, Issue 6, June 2023, pgad163, https://doi.org/10.1093/pnasnexus/pgad163
PubDate: Wed, 15 Nov 2023 00:00:00 GMT
DOI: 10.1093/pnasnexus/pgad377
Issue No: Vol. 2, No. 11 (2023)
- Correction to: Vaccine-hesitant people misperceive the social norm of
vaccination
First page: pgad366
Abstract: This is a correction to: Eva Vriens, Luca Tummolini, Giulia Andrighetto, Vaccine-hesitant people misperceive the social norm of vaccination, PNAS Nexus, Volume 2, Issue 5, May 2023, pgad132, https://doi.org/10.1093/pnasnexus/pgad132
PubDate: Wed, 15 Nov 2023 00:00:00 GMT
DOI: 10.1093/pnasnexus/pgad366
Issue No: Vol. 2, No. 11 (2023)
- Correction to: On the interplay of hierarchies, conflicts, and
cooperation: An experimental approach
First page: pgad367
Abstract: This is a correction to: Pablo Lozano, Alberto Antonioni, Angel Sánchez, On the interplay of hierarchies, conflicts, and cooperation: An experimental approach, PNAS Nexus, Volume 2, Issue 1, January 2023, pgac283, https://doi.org/10.1093/pnasnexus/pgac283
PubDate: Wed, 15 Nov 2023 00:00:00 GMT
DOI: 10.1093/pnasnexus/pgad367
Issue No: Vol. 2, No. 11 (2023)
- Correction to: Maternal nutritional status modifies heat-associated growth
restriction in women with chronic malnutrition
First page: pgad368
Abstract: This is a correction to: Kartik Shankar, Sumera A Ali, Meghan L Ruebel, Saleem Jessani, Sarah J Borengasser, Stephanie P Gilley, Puujee Jambal, Deaunabah N Yazza, Nicholas Weaver, Jennifer F Kemp, Jamie L Westcott, Audrey E Hendricks, Sarah Saleem, Robert L Goldenberg, K Michael Hambidge, Nancy F Krebs, Maternal nutritional status modifies heat-associated growth restriction in women with chronic malnutrition, PNAS Nexus, Volume 2, Issue 1, January 2023, pgac309, https://doi.org/10.1093/pnasnexus/pgac309
PubDate: Wed, 15 Nov 2023 00:00:00 GMT
DOI: 10.1093/pnasnexus/pgad368
Issue No: Vol. 2, No. 11 (2023)
- MOS4-associated complex contributes to proper splicing and suppression of
ER stress under long-term heat stress in Arabidopsis
First page: pgad329
Abstract: AbstractPlants are often exposed not only to short-term (S-) but also to long-term (L-)heat stress over several consecutive days. A few Arabidopsis mutants defective in L-heat tolerance have been identified, but the molecular mechanisms are less understood for this tolerance than for S-heat stress tolerance. To elucidate the mechanisms of the former, we used a forward genetic screen for sensitive to long-term heat (sloh) mutants and isolated sloh3 and sloh63. The mutants were hypersensitive to L- but not to S-heat stress, and sloh63 was also hypersensitive to salt stress. We identified the causal genes, SLOH3 and SLOH63, both of which encoded splicing-related components of the MOS4-associated complex (MAC). This complex is widely conserved in eukaryotes and has been suggested to interact with spliceosomes. Both genes were induced by L-heat stress in a time-dependent manner, and some abnormal splicing events were observed in both mutants under L-heat stress. In addition, endoplasmic reticulum (ER) stress and subsequent unfolded protein response occurred in both mutants under L-heat stress and were especially prominent in sloh63, suggesting that enhanced ER stress is due to the salt hypersensitivity of sloh63. Splicing inhibitor pladienolide B led to concentration-dependent disturbance of splicing, decreased L-heat tolerance, and enhanced ER stress. These findings suggest that maintenance of precise mRNA splicing under L-heat stress by the MAC is important for L-heat tolerance and suppressing ER stress in Arabidopsis.
PubDate: Tue, 14 Nov 2023 00:00:00 GMT
DOI: 10.1093/pnasnexus/pgad329
Issue No: Vol. 2, No. 11 (2023)
- LHT1/MAC7 contributes to proper alternative splicing under long-term heat
stress and mediates variation in the heat tolerance of Arabidopsis
First page: pgad348
Abstract: AbstractNatural genetic variation has facilitated the identification of genes underlying complex traits such as stress tolerances. We here evaluated the long-term (L-) heat tolerance (37°C for 5 days) of 174 Arabidopsis thaliana accessions and short-term (S-) heat tolerance (42°C, 50 min) of 88 accessions and found extensive variation, respectively. Interestingly, L-heat–tolerant accessions are not necessarily S-heat tolerant, suggesting that the tolerance mechanisms are different. To elucidate the mechanisms underlying the variation, we performed a chromosomal mapping using the F2 progeny of a cross between Ms-0 (a hypersensitive accession) and Col-0 (a tolerant accession) and found a single locus responsible for the difference in L-heat tolerance between them, which we named Long-term Heat Tolerance 1 (LHT1). LHT1 is identical to MAC7, which encodes a putative RNA helicase involved in mRNA splicing as a component of the MOS4 complex. We found one amino acid deletion in LHT1 of Ms-0 that causes a loss of function. Arabidopsis mutants of other core components of the MOS4 complex—mos4-2, cdc5-1, mac3a mac3b, and prl1 prl2—also showed hypersensitivity to L-heat stress, suggesting that the MOS4 complex plays an important role in L-heat stress responses. L-heat stress induced mRNA processing–related genes and compromised alternative splicing. Loss of LHT1 function caused genome-wide detrimental splicing events, which are thought to produce nonfunctional mRNAs that include retained introns under L-heat stress. These findings suggest that maintaining proper alternative splicing under L-heat stress is important in the heat tolerance of A. thaliana.
PubDate: Tue, 14 Nov 2023 00:00:00 GMT
DOI: 10.1093/pnasnexus/pgad348
Issue No: Vol. 2, No. 11 (2023)
- Goblet cell interactions reorient bundled mucus strands for efficient
airway clearance
First page: pgad388
Abstract: AbstractThe respiratory tract of larger animals is cleared by sweeping bundled strands along the airway surface. These bundled strands can be millimetric in length and consist of MUC5B mucin. They are produced by submucosal glands, and upon emerging from these glands, the long axis of the bundled strands is oriented along the cilia-mediated flow toward the oral cavity. However, after release, the bundled strands are found to have turned orthogonal to the flow, which maximizes their clearance potential. How this unexpected reorientation is accomplished is presently not well understood. Recent experiments suggest that the reorientation process involves bundled strands sticking to MUC5AC mucus threads, which are tethered to the goblet cells. Such goblet cells are present in small numbers throughout the airway epithelium. Here, we develop a minimal model for reorientation of bundled mucus strands through adhesive interactions with surface goblet cells. Our simulations reveal that goblet cell interactions can reorient the bundled strands within 10 mm of release—making reorientation on the length scale of the tracheal tube feasible—and can stabilize the orthogonal orientation. Our model also reproduces other experimental observations such as strong velocity fluctuations and significant slow-down of the bundled strand with respect to the cilia-mediated flow. We further provide insight into the strand turning mechanism by examining the effect of strand shape on the impulse exerted by a single goblet cell. We conclude that goblet cell–mediated reorientation is a viable route for bundled strand reorientation, which should be further validated in future experiment.
PubDate: Fri, 10 Nov 2023 00:00:00 GMT
DOI: 10.1093/pnasnexus/pgad388
Issue No: Vol. 2, No. 11 (2023)
- Rhomboid protease RHBDL4/RHBDD1 cleaves SREBP-1c at endoplasmic reticulum
monitoring and regulating fatty acids
First page: pgad351
Abstract: AbstractThe endoplasmic reticulum (ER)–embedded transcription factors, sterol regulatory element-binding proteins (SREBPs), master regulators of lipid biosynthesis, are transported to the Golgi for proteolytic activation to tune cellular cholesterol levels and regulate lipogenesis. However, mechanisms by which the cell responds to the levels of saturated or unsaturated fatty acids remain underexplored. Here, we show that RHBDL4/RHBDD1, a rhomboid family protease, directly cleaves SREBP-1c at the ER. The p97/VCP, AAA-ATPase complex then acts as an auxiliary segregase to extract the remaining ER-embedded fragment of SREBP-1c. Importantly, the enzymatic activity of RHBDL4 is enhanced by saturated fatty acids (SFAs) but inhibited by polyunsaturated fatty acids (PUFAs). Genetic deletion of RHBDL4 in mice fed on a Western diet enriched in SFAs and cholesterol prevented SREBP-1c from inducing genes for lipogenesis, particularly for synthesis and incorporation of PUFAs, and secretion of lipoproteins. The RHBDL4-SREBP-1c pathway reveals a regulatory system for monitoring fatty acid composition and maintaining cellular lipid homeostasis.
PubDate: Wed, 08 Nov 2023 00:00:00 GMT
DOI: 10.1093/pnasnexus/pgad351
Issue No: Vol. 2, No. 11 (2023)
- Quantifying leadership in climate negotiations: A social power game
First page: pgad365
Abstract: AbstractWe consider complex multistage multiagent negotiation processes such as those occurring at climate conferences and ask ourselves how can an agent maximize its social power, intended as influence over the outcome of the negotiation. This question can be framed as a strategic game played over an opinion dynamics model, in which the action of an agent consists in stubbornly defending its own opinion. We show that for consensus-seeking opinion dynamics models in which the interaction weights are uniform, the optimal action obeys to an early mover advantage principle, i.e. the agents behaving stubbornly in the early phases of the negotiations achieve the highest social power. When looking at data collected from the climate change negotiations going on at the United Nations Framework Convention on Climate Change, we find evidence of the use of the early mover strategy. Furthermore, we show that the social powers computed through our model correlate very well with the perceived leadership roles assessed through independent survey data, especially when non-uniform weights incorporating economical and demographic factors are considered.
PubDate: Tue, 07 Nov 2023 00:00:00 GMT
DOI: 10.1093/pnasnexus/pgad365
Issue No: Vol. 2, No. 11 (2023)
- Aberrant mitochondrial dynamics contributes to diaphragmatic weakness
induced by mechanical ventilation
First page: pgad336
Abstract: AbstractIn critical care patients, the “”temporary inactivity of the diaphragm caused by mechanical ventilation (MV) triggers a series of events leading to diaphragmatic dysfunction and atrophy, commonly known as ventilator-induced diaphragm dysfunction (VIDD). While mitochondrial dysfunction related to oxidative stress is recognized as a crucial factor in VIDD, the exact molecular mechanism remains poorly understood. In this study, we observe that 6 h of MV triggers aberrant mitochondrial dynamics, resulting in a reduction in mitochondrial size and interaction, associated with increased expression of dynamin-related protein 1 (DRP1). This effect can be prevented by P110, a molecule that inhibits the recruitment of DRP1 to the mitochondrial membrane. Furthermore, isolated mitochondria from the diaphragms of ventilated patients exhibited increased production of reactive oxygen species (ROS). These mitochondrial changes were associated with the rapid oxidation of type 1 ryanodine receptor (RyR1) and a decrease in the stabilizing subunit calstabin 1. Subsequently, we observed that the sarcoplasmic reticulum (SR) in the ventilated diaphragms showed increased calcium leakage and reduced contractile function. Importantly, the mitochondrial fission inhibitor P110 effectively prevented all of these alterations. Taken together, the results of our study illustrate that MV leads, in the diaphragm, to both mitochondrial fragmentation and dysfunction, linked to the up-/down-regulation of 320 proteins, as assessed through global comprehensive quantitative proteomics analysis, primarily associated with mitochondrial function. These outcomes underscore the significance of developing compounds aimed at modulating the balance between mitochondrial fission and fusion as potential interventions to mitigate VIDD in human patients.
PubDate: Tue, 07 Nov 2023 00:00:00 GMT
DOI: 10.1093/pnasnexus/pgad336
Issue No: Vol. 2, No. 11 (2023)
- A missing jigsaw within the hygiene hypothesis: Low-dose bisphenol A
exposure attenuates lipopolysaccharide-induced asthma protection
First page: pgad312
Abstract: AbstractThe rising occurrence of allergic asthma in early life across industrialized countries suggests that environmental factors play a crucial role in determining asthma susceptibility and severity. While prior exposure to microbial lipopolysaccharides (LPSs) has been found to offer protection against allergic asthma, infants residing in urban environments are increasingly exposed to environmental pollutants. Utilizing limulus lysate test screens and virtual screening models, we identified pollutants that can modulate LPS bioactivity. This investigation revealed that bisphenol A (BPA), a chemical commonly used in numerous household items and previously implicated in obesity and cancer, effectively neutralizes LPS. In-depth mechanistic analyses showed that BPA specifically binds to the lipid A component of LPS, leading to inactivation. This interaction eliminates the immunostimulatory activity of LPS, making mice more susceptible to house dust mite (HDM)-induced allergic asthma. BPA reactivates lung epithelial cells, consequently amplifying type 2 responses to HDMs in dendritic cells. This chemical interplay provides new insights into the pathophysiology of asthma in relation to human exposure. Understanding the intricate relationships between environmental chemicals and microbial antigens, as well as their impacts on innate immunity, is critical for the development of intervention strategies to address immune disorders resulting from urbanization.
PubDate: Tue, 07 Nov 2023 00:00:00 GMT
DOI: 10.1093/pnasnexus/pgad312
Issue No: Vol. 2, No. 11 (2023)
- Snow patch refugia benefits for species of periglacial zones—Evidence
from a high-elevation obligate
First page: pgad339
Abstract: AbstractConserving Earth's most rapidly changing biomes necessitates understanding biological consequences of altered climes. Past species- and taxa-level responses to warming environs include numerous concentrated extirpations at the southern peripheries of distributions during the late Pleistocene. Less clear are localized capacities of cold-adapted species to mitigate thermal challenges against warming temperatures, especially through proximate behavioral and physiological adjustments. Whereas snow patches persist in periglacial zones and elsewhere, broad reductions in seasonal snow raise concerns about how and why species continue to use them. If snow patches play a functional role to combat increasing thermal demands, we predicted individuals would display an array of autonomic responses to increased temperatures modulated by wind, ambient temperature, and winter fur on and away from snow patches. We tested these predictions using a mammalian exemplar of high latitude and high elevation, mountain goats (Oreamnos americanus), using two sites in the northern Rocky Mountains, USA. Surprisingly, and contrary to expectations of reduced thermal stress, respiration rates were not decreased on snow patches but use of snow was strongly correlated with decreased metrics of insect harassment. As snow cover continues to decline in montane environs, the persistence of cold-adapted species depends on navigating concurrent changes in biotic communities and thermal environments and balancing competing pressures on behavioral and biological responses.
PubDate: Tue, 07 Nov 2023 00:00:00 GMT
DOI: 10.1093/pnasnexus/pgad339
Issue No: Vol. 2, No. 11 (2023)
- The sustainability of trade in wild plants—A data-integration approach
tested on critically endangered Nardostachys jatamansi
First page: pgad328
Abstract: AbstractWhile the demand for many products from wild-harvested plants is growing rapidly, the sustainability of the associated plant trade remains poorly understood and understudied. We integrate ecological and trade data to advance sustainability assessments, using the critically endangered Nardostachys jatamansi in Nepal to exemplify the approach and illustrate the conservation policy gains. Through spatial distribution modeling and structured interviews with traders, wholesalers, and processors, we upscale district-level trade data to provincial and national levels and compare traded amounts to three sustainable harvest scenarios derived from stock and yield data in published inventories and population ecology studies. We find increased trade levels and unsustainable harvesting focused in specific subnational geographical locations. Data reported in government records and to CITES did not reflect estimated trade levels and could not be used to assess sustainability. Our results suggest that changing harvesting practices to promote regeneration would allow country-wide higher levels of sustainable harvests, simultaneously promoting species conservation and continued trade of substantial economic importance to harvesters and downstream actors in the production network. The approach can be applied to other plant species, with indication that quick and low-cost proxies to species distribution modeling may provide acceptable sustainability estimates at aggregated spatial levels.
PubDate: Tue, 07 Nov 2023 00:00:00 GMT
DOI: 10.1093/pnasnexus/pgad328
Issue No: Vol. 2, No. 11 (2023)
- Best billiard ball in the 19th century: Composite materials made of
celluloid and bone as substitutes for ivory
First page: pgad360
Abstract: AbstractThe demystification of how 19th-century novelly designed materials became significant elements of modern technological, economic, and cultural life requires a complete understanding of the material dimensions of historical artifacts. The objects frequently described as the earliest manufactured plastic products—the billiard balls made by John Wesley Hyatt and his associates from the late 1860s—are examined closely for the first time and are found to be more complex and functionally more successful than has been described. Modern analytical techniques such as optical microscopy, scanning electron microscope—energy dispersive X-ray spectroscopy, X-ray fluorescence, micro-Fourier transformed infrared, and handheld/micro-Raman spectroscopies were used to reveal the complex composition of the Smithsonian Institution's “original” 1868 celluloid billiard ball. Comparisons with billiard and pool balls commercialized from the 1880s to the 1960s showed an unexpected consistency in material formulations. All specimens were made of an unprecedented composite material prepared with a mixture of cellulose nitrate, camphor, and ground bone; the source of the bone was identified as cattle by peptide mass fingerprint (ZooMS). Patent specifications and contemporary journal descriptions explained how and when these formulations emerged. Combining the technical analyses of compositions with a careful reading of the historical record and contemporary descriptions reveals the key elements of the first successful efforts to substitute materials to assist the survival of endangered animals.
PubDate: Fri, 03 Nov 2023 00:00:00 GMT
DOI: 10.1093/pnasnexus/pgad360
Issue No: Vol. 2, No. 11 (2023)
- Emergency communications after earthquake reveal social network backbone
of important ties
First page: pgad358
Abstract: AbstractSocial networks provide a basis for collective resilience to disasters. Combining the quasi-experimental context of a major earthquake in Ya’an, China, with anonymized mobile telecommunications records regarding 91,839 Ya’an residents, we use initial bursts of postdisaster communications (e.g. choice of alter, order of calls, and latency) to reveal the “important ties” that form the social network backbone. We find that only 26.8% of important ties activated during the earthquake were the strongest ties during normal times. Many important ties were hitherto latent and weak, only to become persistent and strong after the earthquake. We show that which ties activated during a sudden disaster are best predicted by the interaction of embeddedness and tie strength. Moreover, a backbone of important ties alone (without the inclusion of weak ties ordinarily seen as important to bridge communities) is sufficient to generate a hierarchical structure of social networks that connect a disaster zone's disparate communities.
PubDate: Thu, 02 Nov 2023 00:00:00 GMT
DOI: 10.1093/pnasnexus/pgad358
Issue No: Vol. 2, No. 11 (2023)
- Neighboring inteins interfere with one another's homing capacity
First page: pgad354
Abstract: AbstractInteins are mobile genetic elements that invade conserved genes across all domains of life and viruses. In some instances, a single gene will have several intein insertion sites. In Haloarchaea, the minichromosome maintenance (MCM) protein at the core of replicative DNA helicase contains four intein insertion sites within close proximity, where two of these sites (MCM-a and MCM-d) are more likely to be invaded. A haloarchaeon that harbors both MCM-a and MCM-d inteins, Haloferax mediterranei, was studied in vivo to determine intein invasion dynamics and the interactions between neighboring inteins. Additionally, invasion frequencies and the conservation of insertion site sequences in 129 Haloferacales mcm homologs were analyzed to assess intein distribution across the order. We show that the inteins at MCM-a and MCM-d recognize and cleave their respective target sites and, in the event that only one empty intein invasion site is present, readily initiate homing (i.e. single homing). However, when two inteins are present co-homing into an intein-free target sequence is much less effective. The two inteins are more effective when invading alleles that already contain an intein at one of the two sites. Our in vivo and computational studies also support that having a proline in place of a serine as the first C-terminal extein residue of the MCM-d insertion site prevents successful intein splicing, but does not stop recognition of the insertion site by the intein's homing endonuclease.
PubDate: Fri, 27 Oct 2023 00:00:00 GMT
DOI: 10.1093/pnasnexus/pgad354
Issue No: Vol. 2, No. 11 (2023)
- The response of Arabidopsis to the apocarotenoid β-cyclocitric acid
reveals a role for SIAMESE-RELATED 5 in root development and drought
tolerance
First page: pgad353
Abstract: AbstractNew regulatory functions in plant development and environmental stress responses have recently emerged for a number of apocarotenoids produced by enzymatic or nonenzymatic oxidation of carotenoids. β-Cyclocitric acid (β-CCA) is one such compound derived from β-carotene, which triggers defense mechanisms leading to a marked enhancement of plant tolerance to drought stress. We show here that this response is associated with an inhibition of root growth affecting both root cell elongation and division. Remarkably, β-CCA selectively induced cell cycle inhibitors of the SIAMESE-RELATED (SMR) family, especially SMR5, in root tip cells. Overexpression of the SMR5 gene in Arabidopsis induced molecular and physiological changes that mimicked in large part the effects of β-CCA. In particular, the SMR5 overexpressors exhibited an inhibition of root development and a marked increase in drought tolerance which is not related to stomatal closure. SMR5 up-regulation induced changes in gene expression that strongly overlapped with the β-CCA–induced transcriptomic changes. Both β-CCA and SMR5 led to a down-regulation of many cell cycle activators (cyclins, cyclin-dependent kinases) and a concomitant up-regulation of genes related to water deprivation, cellular detoxification, and biosynthesis of lipid biopolymers such as suberin and lignin. This was correlated with an accumulation of suberin lipid polyesters in the roots and a decrease in nonstomatal leaf transpiration. Taken together, our results identify the β-CCA–inducible and drought-inducible SMR5 gene as a key component of a stress-signaling pathway that reorients root metabolism from growth to multiple defense mechanisms leading to drought tolerance.
PubDate: Thu, 26 Oct 2023 00:00:00 GMT
DOI: 10.1093/pnasnexus/pgad353
Issue No: Vol. 2, No. 11 (2023)
- The multiple activations in budding yeast S-phase checkpoint are Poisson
processes
First page: pgad342
Abstract: AbstractEukaryotic cells activate the S-phase checkpoint signal transduction pathway in response to DNA replication stress. Affected by the noise in biochemical reactions, such activation process demonstrates cell-to-cell variability. Here, through the analysis of microfluidics-integrated time-lapse imaging, we found multiple S-phase checkpoint activations in a certain budding yeast cell cycle. Yeast cells not only varied in their activation moments but also differed in the number of activations within the cell cycle, resulting in a stochastic multiple activation process. By investigating dynamics at the single-cell level, we showed that stochastic waiting times between consecutive activations are exponentially distributed and independent from each other. Finite DNA replication time provides a robust upper time limit to the duration of multiple activations. The mathematical model, together with further experimental evidence from the mutant strain, revealed that the number of activations under different levels of replication stress agreed well with Poisson distribution. Therefore, the activation events of S-phase checkpoint meet the criterion of Poisson process during DNA replication. In sum, the observed Poisson activation process may provide new insights into the complex stochastic dynamics of signal transduction pathways.
PubDate: Thu, 26 Oct 2023 00:00:00 GMT
DOI: 10.1093/pnasnexus/pgad342
Issue No: Vol. 2, No. 11 (2023)
- Interferon ɛ restricts Zika virus infection in the female
reproductive tract
First page: pgad350
Abstract: AbstractInterferon ɛ (IFNɛ) is a unique type I IFN that has been implicated in host defense against sexually transmitted infections. Zika virus (ZIKV), an emerging pathogen, can infect the female reproductive tract (FRT) and cause devastating diseases, particularly in pregnant women. How IFNɛ contributes to protection against ZIKV infection in vivo is unknown. In this study, we show that IFNɛ plays a critical role in host protection against vaginal ZIKV infection in mice. We found that IFNɛ was expressed not only by epithelial cells in the FRT but also by immune and stromal cells at baseline or after exposure to viruses or specific Toll-like receptor (TLR) agonists. IFNɛ-deficient mice exhibited abnormalities in the epithelial border and underlying tissue in the cervicovaginal tract, and these defects were associated with increased susceptibility to vaginal but not subcutaneous ZIKV infection. IFNɛ deficiency resulted in an increase in magnitude, duration, and depth of ZIKV infection in the FRT. Critically, intravaginal administration of recombinant IFNɛ protected Ifnɛ−/− mice and highly susceptible Ifnar1−/− mice against vaginal ZIKV infection, indicating that IFNɛ was sufficient to provide protection even in the absence of signals from other type I IFNs and in an IFNAR1-independent manner. Our findings reveal a potentially critical role for IFNɛ in mediating protection against the transmission of ZIKV in the context of sexual contact.
PubDate: Wed, 25 Oct 2023 00:00:00 GMT
DOI: 10.1093/pnasnexus/pgad350
Issue No: Vol. 2, No. 11 (2023)
- The systemic impact of deplatforming on social media
First page: pgad346
Abstract: AbstractDeplatforming, or banning malicious accounts from social media, is a key tool for moderating online harms. However, the consequences of deplatforming for the wider social media ecosystem have been largely overlooked so far, due to the difficulty of tracking banned users. Here, we address this gap by studying the ban-induced platform migration from Twitter to Gettr. With a matched dataset of 15M Gettr posts and 12M Twitter tweets, we show that users active on both platforms post similar content as users active on Gettr but banned from Twitter, but the latter have higher retention and are 5 times more active. Our results suggest that increased Gettr use is not associated with a substantial increase in user toxicity over time. In fact, we reveal that matched users are more toxic on Twitter, where they can engage in abusive cross-ideological interactions, than Gettr. Our analysis shows that the matched cohort are ideologically aligned with the far-right, and that the ability to interact with political opponents may be part of Twitter’s appeal to these users. Finally, we identify structural changes in the Gettr network preceding the 2023 Brasília insurrections, highlighting the risks that poorly regulated social media platforms may pose to democratic life.
PubDate: Wed, 25 Oct 2023 00:00:00 GMT
DOI: 10.1093/pnasnexus/pgad346
Issue No: Vol. 2, No. 11 (2023)
- Scaling behavior for electric vehicle chargers and road map to addressing
the infrastructure gap
First page: pgad341
Abstract: AbstractEnabling widespread electric vehicle (EV) adoption requires a substantial build-out of charging infrastructure in the coming decade. We formulate the charging infrastructure needs as a scaling analysis problem and use it to estimate the EV infrastructure needs of the USA at a county-level resolution. We find that gasoline and EV charging stations scale sub-linearly with their respective vehicle registrations, recovering the sub-linear scaling typical of infrastructure. Surprisingly, we find that EV charging stations scale super-linearly with population size within counties, deviating from the sub-linear scaling of gasoline stations. We discuss how this demonstrates the infancy of both EVs and EV infrastructure while providing a framework for estimating future EV infrastructure demands. By considering the power delivery of existing gasoline stations, and appropriate EV efficiencies, we estimate the EV infrastructure gap at the county level, providing a road map for future EV infrastructure expansion.
PubDate: Wed, 25 Oct 2023 00:00:00 GMT
DOI: 10.1093/pnasnexus/pgad341
Issue No: Vol. 2, No. 11 (2023)
- A key to wine conservation lies in the glass–cork interface
First page: pgad344
Abstract: AbstractThis study investigates the evolution of the oxygen barrier properties of the bottleneck–stopper system under conditions simulating the conservation of wine in the bottle (presence of model wine, storage position, and temperature) over a long aging period of 24 months. The results highlighted that the oxygen diffusion coefficient of the stopper alone is not modified regardless of the storage conditions. At 20°C, the presence of model wine favors oxygen transfer at the glass–cork interface, accounting for nearly 75% of total oxygen transfer in comparison to cork studied without model wine. Yet, the position of the bottle during storage, vertical (i.e. cork in contact with the vapor phase of the model wine) or horizontal (i.e. cork in contact with the liquid phase), does not influence the oxygen transfer. At higher storage temperatures (35 and 50°C), the barrier properties of the bottleneck–cork system remain stable up to 9 and 3 months, respectively. After this period, an alteration of the barrier properties is observed with an increase of the transfer at the glass–cork interface.
PubDate: Sat, 21 Oct 2023 00:00:00 GMT
DOI: 10.1093/pnasnexus/pgad344
Issue No: Vol. 2, No. 11 (2023)
- Ablation of OCT4 function in cattle embryos by double electroporation of
CRISPR-Cas for DNA and RNA targeting (CRISPR-DART)
First page: pgad343
Abstract: AbstractCRISPR-Cas ribonucleoproteins (RNPs) are important tools for gene editing in preimplantation embryos. However, the inefficient production of biallelic deletions in cattle zygotes has hindered mechanistic studies of gene function. In addition, the presence of maternal RNAs that support embryo development until embryonic genome activation may cause confounding phenotypes. Here, we aimed to improve the efficiency of biallelic deletions and deplete specific maternal RNAs in cattle zygotes using CRISPR-Cas editing technology. Two electroporation sessions with Cas9D10A RNPs targeting exon 1 and the promoter of OCT4 produced biallelic deletions in 91% of the embryos tested. In most cases, the deletions were longer than 1,000 nucleotides long. Electroporation of Cas13a RNPs prevents the production of the corresponding proteins. We electroporated Cas9D10A RNPs targeting exon 1, including the promoter region, of OCT4 in two sessions with inclusion of Cas13a RNPs targeting OCT4 mRNAs in the second session to ablate OCT4 function in cattle embryos. A lack of OCT4 resulted in embryos arresting development prior to blastocyst formation at a greater proportion (13%) than controls (31.6%, P < 0.001). The few embryos that developed past the morula stage did not form a normal inner cell mass. Transcriptome analysis of single blastocysts, confirmed to lack exon 1 and promoter region of OCT4, revealed a significant (False Discovery Rate, FDR < 0.1) reduction in transcript abundance of many genes functionally connected to stemness, including markers of pluripotency (CADHD1, DPPA4, GNL3, RRM2). The results confirm that OCT4 is a key regulator of genes that modulate pluripotency and is required to form a functional blastocyst in cattle.
PubDate: Fri, 20 Oct 2023 00:00:00 GMT
DOI: 10.1093/pnasnexus/pgad343
Issue No: Vol. 2, No. 11 (2023)
- Arrhythmia-associated calmodulin variants interact with KCNQ1 to confer
aberrant membrane trafficking and function
First page: pgad335
Abstract: AbstractMissense variants in calmodulin (CaM) predispose patients to arrhythmias associated with high mortality rates (“calmodulinopathy”). As CaM regulates many key cardiac ion channels, an understanding of disease mechanism associated with CaM variant arrhythmias requires elucidating individual CaM variant effects on distinct channels. One key CaM regulatory target is the KCNQ1 (KV7.1) voltage-gated potassium channel that carries the IKs current. Yet, relatively little is known as to how CaM variants interact with KCNQ1 or affect its function. Here, we take a multipronged approach employing a live-cell fluorescence resonance energy transfer binding assay, fluorescence trafficking assay, and functional electrophysiology to characterize >10 arrhythmia-associated CaM variants for effect on KCNQ1 CaM binding, membrane trafficking, and channel function. We identify one variant (G114W) that exhibits severely weakened binding to KCNQ1 but find that most other CaM variants interact with similar binding affinity to KCNQ1 when compared with CaM wild-type over physiological Ca2+ ranges. We further identify several CaM variants that affect KCNQ1 and IKs membrane trafficking and/or baseline current activation kinetics, thereby delineating KCNQ1 dysfunction in calmodulinopathy. Lastly, we identify CaM variants with no effect on KCNQ1 function. This study provides extensive functional data that reveal how CaM variants contribute to creating a proarrhythmic substrate by causing abnormal KCNQ1 membrane trafficking and current conduction. We find that CaM variant regulation of KCNQ1 is not uniform with effects varying from benign to significant loss of function, suggesting how CaM variants predispose patients to arrhythmia via the dysregulation of multiple cardiac ion channels.Classification: Biological, Health, and Medical Sciences, Physiology
PubDate: Sat, 14 Oct 2023 00:00:00 GMT
DOI: 10.1093/pnasnexus/pgad335
Issue No: Vol. 2, No. 11 (2023)
- Extending aquatic spectral information with the first radiometric IR-B
field observations
First page: pgad340
Abstract: AbstractPlanetary radiometric observations enable remote sensing of biogeochemical parameters to describe spatiotemporal variability in aquatic ecosystems. For approximately the last half century, the science of aquatic radiometry has established a knowledge base using primarily, but not exclusively, visible wavelengths. Scientific subdisciplines supporting aquatic radiometry have evolved hardware, software, and procedures to maximize competency for exploiting visible wavelength information. This perspective culminates with the science requirement that visible spectral resolution must be continually increased to extract more information. Other sources of information, meanwhile, remain underexploited, particularly information from nonvisible wavelengths. Herein, absolute radiometry is used to evaluate spectral limits for deriving and exploiting aquatic data products, specifically the normalized water-leaving radiance, Γ(λ), and its derivative products. Radiometric observations presented herein are quality assured for individual wavebands, and spectral verification is conducted by analyzing celestial radiometric results, comparing agreement of above- and in-water observations at applicable wavelengths, and evaluating consistency with bio-optical models and optical theory. The results presented include the first absolute radiometric field observations of Γ(λ) within the IR-B spectral domain (i.e. spanning 1400–3000 nm), which indicate that IR-B signals confer greater and more variable flux than formerly ascribed. Black-pixel processing, a routine correction in satellite and in situ aquatic radiometry wherein a spectrum is offset corrected relative to a nonvisible waveband (often IR-B or a shorter legacy waveband) set to a null value, is shown to degrade aquatic spectra and derived biogeochemical parameters.
PubDate: Sat, 14 Oct 2023 00:00:00 GMT
DOI: 10.1093/pnasnexus/pgad340
Issue No: Vol. 2, No. 11 (2023)
- Recursive neural programs: A differentiable framework for learning
compositional part-whole hierarchies and image grammars
First page: pgad337
Abstract: AbstractHuman vision, thought, and planning involve parsing and representing objects and scenes using structured representations based on part-whole hierarchies. Computer vision and machine learning researchers have recently sought to emulate this capability using neural networks, but a generative model formulation has been lacking. Generative models that leverage compositionality, recursion, and part-whole hierarchies are thought to underlie human concept learning and the ability to construct and represent flexible mental concepts. We introduce Recursive Neural Programs (RNPs), a neural generative model that addresses the part-whole hierarchy learning problem by modeling images as hierarchical trees of probabilistic sensory-motor programs. These programs recursively reuse learned sensory-motor primitives to model an image within different spatial reference frames, enabling hierarchical composition of objects from parts and implementing a grammar for images. We show that RNPs can learn part-whole hierarchies for a variety of image datasets, allowing rich compositionality and intuitive parts-based explanations of objects. Our model also suggests a cognitive framework for understanding how human brains can potentially learn and represent concepts in terms of recursively defined primitives and their relations with each other.
PubDate: Sat, 14 Oct 2023 00:00:00 GMT
DOI: 10.1093/pnasnexus/pgad337
Issue No: Vol. 2, No. 11 (2023)
- Deep learning unmasks the ECG signature of Brugada syndrome
First page: pgad327
Abstract: AbstractOne in 10 cases of sudden cardiac death strikes without warning as the result of an inherited arrhythmic cardiomyopathy, such as Brugada Syndrome (BrS). Normal physiological variations often obscure visible signs of this and related life-threatening channelopathies in conventional electrocardiograms (ECGs). Sodium channel blockers can reveal previously hidden diagnostic ECG features, however, their use carries the risk of life-threatening proarrhythmic side effects. The absence of a nonintrusive test places a grossly underestimated fraction of the population at risk of SCD. Here, we present a machine-learning algorithm that extracts, aligns, and classifies ECG waveforms for the presence of BrS. This protocol, which succeeds without the use of a sodium channel blocker (88.4% accuracy, 0.934 AUC in validation), can aid clinicians in identifying the presence of this potentially life-threatening heart disease.
PubDate: Fri, 13 Oct 2023 00:00:00 GMT
DOI: 10.1093/pnasnexus/pgad327
Issue No: Vol. 2, No. 11 (2023)
- Discovery of microRNAs in Pyrus stigma exudates opens new research avenues
in Horticulture
First page: pgad332
Abstract: AbstractIn many plant species, flower stigma secretions are important in early stages of sexual reproduction. Previous chemical analysis and proteomic characterization of these exudates provided insights into their biological function. Nevertheless, the presence of nucleic acids in the stigma exudates has not been previously reported. Here, we studied the stigma exudates of Pyrus communis, Pyrus pyrifolia, and Pyrus syriaca and showed them to harbor extracellular RNAs of various sizes. RNA sequencing revealed, for the first time, the presence of known Rosaceae mature microRNAs (miRs), also abundant in the stigma source tissue. Predicted targets of the exudate miRs in the Arabidopsis thaliana genome include genes involved in various biological processes. Several of these genes are pollen transcribed, suggesting possible involvement of exudate miRs in transcriptional regulation of the pollen. Moreover, extracellular miRs can potentially act across kingdoms and target genes of stigma interacting organisms/microorganisms, thus opening novel applicative avenues in Horticulture.
PubDate: Thu, 12 Oct 2023 00:00:00 GMT
DOI: 10.1093/pnasnexus/pgad332
Issue No: Vol. 2, No. 11 (2023)
