bluuebunny/crossref_metadata_2025 huggingface dataset:
Biome-scale temperature sensitivity of ecosystem respiration revealed by atmospheric CO2 observations
Authors: Sun Wu , Luo Xiangzhong , Fang Yuanyuan , Shiga Yoichi P. , Zhang Yao , Fisher Joshua B. , Keenan Trevor F. , Michalak Anna M.
Published: June 2023

The temperature sensitivity of ecosystem respiration regulates how the terrestrial carbon sink responds to a warming climate but has been difficult to constrain observationally beyond the plot scale. Here we use observations of atmospheric CO2 concentrations from a network of towers together with carbon flux estimates from state-of-the-art terrestrial biosphere models to characterize the temperature sensitivity of ecosystem respiration, as represented by the Arrhenius activation energy, over various North American biomes. We infer activation energies of 0.43 eV for North America and 0.38 eV to 0.53 eV for major biomes therein, which are substantially below those reported for plot-scale studies (approximately 0.65 eV). This discrepancy suggests that sparse plot-scale observations do not capture the spatial-scale dependence and biome specificity of the temperature sensitivity. We further show that adjusting the apparent temperature sensitivity in model estimates markedly improves their ability to represent observed atmospheric CO2 variability. This study provides observationally constrained estimates of the temperature sensitivity of ecosystem respiration directly at the biome scale and reveals that temperature sensitivities at this scale are lower than those based on earlier plot-scale studies. These findings call for additional work to assess the resilience of large-scale carbon sinks to warming.
Magnetic flux trapping in hydrogen-rich high-temperature superconductors
Authors: Minkov V. S. , Ksenofontov V. , Bud’ko S. L. , Talantsev E. F. , Eremets M. I.
Published: June 2023

Recent discoveries of superconductivity in various hydrides at high pressures have shown that a critical temperature of superconductivity can reach near-room-temperature values. However, experimental studies are limited by high-pressure conditions, and electrical transport measurements have been the primary technique for detecting superconductivity in hydrides. Here we implement a non-conventional protocol for the magnetic measurements of superconductors in a SQUID magnetometer and probe the trapped magnetic flux in two near-room-temperature superconductors H3S and LaH10 at high pressures. Contrary to traditional magnetic susceptibility measurements, the magnetic response from the trapped flux is almost unaffected by the background signal of the diamond anvil cell due to the absence of external magnetic fields. The behaviour of the trapped flux generated under zero-field-cooled and field-cooled conditions proves the existence of superconductivity in these materials. We reveal that the absence of a pronounced Meissner effect is associated with the very strong pinning of vortices inside the samples. This approach can also be a tool for studying multiphase samples or samples that have a low superconducting fraction at ambient pressure.
Sequential and directional insulation by conserved CTCF sites underlies the Hox timer in stembryos
Authors: Rekaik Hocine , Lopez-Delisle Lucille , Hintermann Aurélie , Mascrez Bénédicte , Bochaton Célia , Mayran Alexandre , Duboule Denis
Published: June 2023

During development, Hox genes are temporally activated according to their relative positions on their clusters, contributing to the proper identities of structures along the rostrocaudal axis. To understand the mechanism underlying this Hox timer, we used mouse embryonic stem cell-derived stembryos. Following Wnt signaling, the process involves transcriptional initiation at the anterior part of the cluster and a concomitant loading of cohesin complexes enriched on the transcribed DNA segments, that is, with an asymmetric distribution favoring the anterior part of the cluster. Chromatin extrusion then occurs with successively more posterior CTCF sites acting as transient insulators, thus generating a progressive time delay in the activation of more posterior-located genes due to long-range contacts with a flanking topologically associating domain. Mutant stembryos support this model and reveal that the presence of evolutionary conserved and regularly spaced intergenic CTCF sites controls the precision and the pace of this temporal mechanism.
A high spatial resolution dataset of China’s biomass resource potential
Authors: Wang Rui , Cai Wenjia , Yu Le , Li Wei , Zhu Lei , Cao Bowen , Li Jin , Shen Jianxiang , Zhang Shihui , Nie Yaoyu , Wang Can
Published: June 2023

Assessing biomass resource potential is essential for China’s ambitious goals of carbon neutrality, rural revitalization, and poverty eradication. To fill the data gap of high spatial resolution biomass resources in China, this study estimates the biomass resource potential for all types of lignocellulosic biomass feedstock at 1 km resolution in 2018, including 9 types of agricultural residues, 11 types of forestry residues, and 5 types of energy crops. By combining the statistical accounting method and the GIS-based method, this study develops a transparent and comprehensive assessment framework, which is in accordance with the principle of food security, forest land and pasture protection, and biodiversity protection. In the end, we organize and store the data in different formats (GeoTIFF, NetCDF, and Excel) for GIS users, integrated modelers, and policymakers. The reliability of this high spatial resolution dataset has been proved by comparing the aggregated data at the subnational and national levels with the existing literature. This dataset has numerous potential uses and is a crucial input to many bioenergy-related studies.
DFT and QSAR studies of PTFE/ZnO/SiO2 nanocomposite
Authors: Ezzat Hend A. , Hegazy Maroof A. , Ghoneim Rasha , Zahran Heba Y. , Yahia Ibrahim S. , Elhaes Hanan , Refaat Ahmed , Ibrahim Medhat A.
Published: June 2023

Polytetrafluoroethylene (PTFE) is one of the most significant fluoropolymers, and one of the most recent initiatives is to increase its performance by using metal oxides (MOs). Consequently, the surface modifications of PTFE with two metal oxides (MOs), SiO2 and ZnO, individually and as a mixture of the two MOs, were modeled using density functional theory (DFT). The B3LYPL/LANL2DZ model was used in the studies conducted to follow up the changes in electronic properties. The total dipole moment (TDM) and HOMO/LUMO band gap energy (∆E) of PTFE, which were 0.000 Debye and 8.517 eV respectively, were enhanced to 13.008 Debye and 0.690 eV in the case of PTFE/4ZnO/4SiO2. Moreover, with increasing nano filler (PTFE/8ZnO/8SiO2), TDM changed to 10.605 Debye and ∆E decreased to 0.273 eV leading to further improvement in the electronic properties. The molecular electrostatic potential (MESP) and quantitative structure activity relationship (QSAR) studies revealed that surface modification of PTFE with ZnO and SiO2 increased its electrical and thermal stability. The improved PTFE/ZnO/SiO2 composite can, therefore, be used as a self-cleaning layer for astronaut suits based on the findings of relatively high mobility, minimal reactivity to the surrounding environment, and thermal stability.
Visiting nature is associated with lower socioeconomic inequalities in well-being in Wales
Authors: Garrett Joanne K. , Rowney Francis M. , White Mathew P. , Lovell Rebecca , Fry Rich J. , Akbari Ashley , Geary Rebecca , Lyons Ronan A. , Mizen Amy , Nieuwenhuijsen Mark , Parker Chrissie , Song Jiao , Stratton Gareth , Thompson Daniel A. , Watkins Alan , White James , Williams Susan A. , Rodgers Sarah E. , Wheeler Benedict W.
Published: June 2023

Natural environments can promote well-being through multiple mechanisms. Many studies have investigated relationships between residential green/blue space (GBS) and well-being, fewer explore relationships with actual use of GBS. We used a nationally representative survey, the National Survey for Wales, anonymously linked with spatial GBS data to investigate associations of well-being with both residential GBS and time in nature (N = 7631). Both residential GBS and time spent in nature were associated with subjective well-being. Higher green-ness was associated with lower well-being, counter to hypotheses (predicting the Warwick and Edinburgh Mental Well-Being Scale (WEMWBS): Enhanced vegetation index β =  − 1.84, 95% confidence interval (CI) − 3.63, − 0.05) but time spent in nature was associated with higher well-being (four hours a week in nature vs. none β = 3.57, 95% CI 3.02, 4.13). There was no clear association between nearest GBS proximity and well-being. In support of the equigenesis theory, time spent in nature was associated with smaller socioeconomic inequalities in well-being. The difference in WEMWBS (possible range 14–70) between those who did and did not live in material deprivation was 7.7 points for those spending no time in nature, and less at 4.5 points for those spending time in nature up to 1 h per week. Facilitating access and making it easier for people to spend time in nature may be one way to reduce socioeconomic inequalities in well-being.
Characterization of a new natural novel lignocellulose fiber resource from the stem of Cyperus platystylis R.Br.
Authors: Bhunia Anup Kumar , Mondal Dheeman , Parui Sanjukta Mondal , Mondal Amal Kumar
Published: June 2023

This study deals with the characterization of a natural fiber which is extracted from the stem of an unexplored plant of Cyperus platystylis R.Br. (CPS) with an aim to establish it as a potent alternative fiber for the plant fiber-based industries. CPS fiber has been investigated for its physical, chemical, thermal, mechanical, and morphological characteristics. The presence of different functional groups in CPS fiber i.e., cellulose, hemicellulose, and lignin which was ensured by Fourier Transformed Infrared (FTIR) Spectrophotometer analysis. X-ray diffraction and chemical constituent analysis revealed high cellulose content and crystallinity i.e., 66.1% and 41.12% respectively, which is comparatively moderate in the case of CPS fiber. Scherrer's equation has been used to determine crystallite size i.e., 2.28 nm. The mean length and diameter of the CPS fiber were 382.0 and 23.36 μm, respectively. The maximum tensile strength was obtained at 657 ± 58.8 MPa for 50 mm fiber and young’s modulus 88.76 ± 30.42 MPa for 50 mm fiber. The required energy to break has been recorded at 346.16 J. Thermal analysis revealed that CPS fibers have thermal stability up to 279 °C. The unique Cyperus platystylis stem fibers could therefore be a suitable reinforcement material for the bio-composites used in semi-structural applications since they have higher functional qualities.
The flow of an Eyring Powell Nanofluid in a porous peristaltic channel through a porous medium
Authors: Nadeem Sohail , Mushtaq Aiman , Alzabut Jehad , Ghazwani Hassan Ali , Eldin Sayed M.
Published: June 2023

In a porous medium, we have examined sinusoidal two-dimensional transport enclosed porous peristaltic boundaries having an Eyring Powell fluid with a water containing $$\text{Al}_{2}{\text{O}}_{3}$$

Al
2

O
3

. The determining momentum and temperature equations are solved semi-analytically by using regular perturbation method and Mathematica. In present research only free pumping case and small amplitude ratio is studied. Mathematical and pictorial consequences are investigated for distinct physical parameters of interest like porosity, viscosity, volume fraction and permeability to check the effects of flow velocity and temperature.
Electrospun nanofiber membrane diameter prediction using a combined response surface methodology and machine learning approach
Authors: Pervez Md. Nahid , Yeo Wan Sieng , Mishu Mst. Monira Rahman , Talukder Md. Eman , Roy Hridoy , Islam Md. Shahinoor , Zhao Yaping , Cai Yingjie , Stylios George K. , Naddeo Vincenzo
Published: June 2023

Despite the widespread interest in electrospinning technology, very few simulation studies have been conducted. Thus, the current research produced a system for providing a sustainable and effective electrospinning process by combining the design of experiments with machine learning prediction models. Specifically, in order to estimate the diameter of the electrospun nanofiber membrane, we developed a locally weighted kernel partial least squares regression (LW-KPLSR) model based on a response surface methodology (RSM). The accuracy of the model's predictions was evaluated based on its root mean square error (RMSE), its mean absolute error (MAE), and its coefficient of determination (R2). In addition to principal component regression (PCR), locally weighted partial least squares regression (LW-PLSR), partial least square regression (PLSR), and least square support vector regression model (LSSVR), some of the other types of regression models used to verify and compare the results were fuzzy modelling and least square support vector regression model (LSSVR). According to the results of our research, the LW-KPLSR model performed far better than other competing models when attempting to forecast the membrane's diameter. This is made clear by the much lowerRMSEandMAEvalues of the LW-KPLSR model. In addition, it offered the highest R2values that could be achieved, reaching 0.9989.
Magnetic field coupling with lunar soil simulants
Authors: Garman Shanti M. , Roth Melissa C. , Roux Vincent G. , Smith Joshua R.
Published: June 2023

Wireless power transfer (WPT) using magnetically coupled resonators is being integrated into space vehicles destined for the lunar surface. The dusty soil on the Moon, called lunar regolith, is known to adhere to surfaces and is also known to contain iron, including iron oxides and metallic iron. Regolith samples are limited, and lunar soil simulants are commonly used in space science research for efforts in surface vehicle navigation, in-situ resource utilization, and power infrastructure. However, most simulants contain no metallic iron, and research involving electromagnetic field interactions with regolith would benefit from incorporating metallic iron into test samples. This work presents experimental results from tests using WPT with magnetically coupled resonators in the presence of various standard lunar simulants, plus a new iron-enriched simulant and metallic iron powders. Results for power transfer efficiency, thermal response, and frequency response are presented and demonstrate that the presence of metallic iron and its particle size are critical factors affecting the coupling of the incident magnetic field with lunar simulants and iron powder samples. The importance of particle size-to-skin depth ratio is discussed. Attenuation constants for various iron powders are estimated from experimental data and compared to those of lunar regolith and simulants.
Biogenic apatite in carbonate concretions with and without fossils investigated in situ by micro-Raman spectroscopy
Authors: Kitanaka Ryosuke , Tsuboi Motohiro , Ozaki Yukihiro
Published: June 2023

Micro-Raman spectra of concretions with and without fossils were measured in a nondestructive manner. The band position and full width at half maximum height (FWHM) of ν1-PO43− of apatite in the concretions were analyzed to investigate the origin of apatite. The analyzed concretions were derived from the Kita-ama Formation of the Izumi Group, Japan. The micro-Raman analysis showed that the apatites in the concretions were divided into two groups: Group W (wide FWHM group) and Group N (narrow FWHM group). The apatite belonging to Group W is suggested to be biogenic apatite originating from the soft body tissues of organisms because the Sr content is high and the FWHM is similar to that of apatite in bones and teeth of present-day animals. The other apatite belonging to Group N is considered affected by the diagenetic process because of its narrow FWHM and F substitution. These features of both groups were observed regardless of the presence of fossils or absence of fossils in the concretions. This Raman spectroscopic study suggests that the apatite at the time of concretion formation belonged to Group W but was changed to Group N by the substitution of F during the diagenesis process.
Intrathecal Th17-driven inflammation is associated with prolonged post-treatment convalescence for patients with Lyme neuroborreliosis
Authors: Gyllemark Paula , Sjöwall Johanna , Forsberg Pia , Ernerudh Jan , Henningsson Anna J.
Published: June 2023

Lyme neuroborreliosis (LNB) is associated with increased levels of pro-inflammatory cytokines and chemokines in the cerebrospinal fluid (CSF). Residual symptoms after antibiotic treatment can have deleterious effects on patients and knowledge regarding the pathogenesis linked to prolonged recovery is lacking. In this prospective follow-up study, we investigated the B cell-associated and T helper (Th) cell-associated immune responses in well-characterized patients with LNB and controls. The aims were to assess the kinetics of selected cytokines and chemokines involved in the inflammatory response and to identify potential prognostic markers. We investigated 13 patients with LNB according to a standardized clinical protocol before antibiotic treatment and after 1, 6 and 12 months of follow-up. CSF and blood samples were obtained at baseline and after 1 month. As controls, we used CSF samples from 37 patients who received spinal anesthesia during orthopedic surgery. The CSF samples were analyzed for CXCL10 (Th1-related), CCL22 (Th2-related) and IL-17A, CXCL1 and CCL20 (Th17-related), as well as for the B cell-related cytokines of a proliferation-inducing ligand (APRIL), B cell-activating factor (BAFF) and CXCL13. The CSF levels of all the cytokines and chemokines, with the exception of APRIL, were significantly higher at baseline in patients with LNB compared with controls. All the cytokines and chemokines, except for IL-17A were significantly reduced at 1-month follow-up. Patients with quick recovery (< 1 month, n = 3) had significantly lower levels of CCL20 at baseline and lower levels of IL-17A at 1-month follow-up. Patients with time of recovery > 6 months (n = 7) had significantly higher levels of IL-17A at the one-month follow-up. No other cytokines or chemokines were associated with prolonged recovery. Dominating residual symptoms were fatigue, myalgia, radiculitis and/or arthralgia. In this prospective follow-up study of patients with LNB, we found significantly lower levels of CCL20 in those who recovered rapidly, and increased levels of IL-17A in patients with delayed recovery post-treatment. Our findings indicate persistent Th17-driven inflammation in the CSF, possibly contributing to a longer convalescence, and suggest IL-17A and CCL20 as potential biomarker candidates for patients with LNB.
Effect of COVID-19 pandemic on inpatient service utilization and patient outcomes in Uganda
Authors: Andia-Biraro Irene , Baluku Joseph Baruch , Olum Ronald , Bongomin Felix , Kyazze Andrew Peter , Ninsiima Sandra , Ssekamatte Phillip , Kibirige Davis , Biraro Samuel , Seremba Emmanuel , Kabugo Charles
Published: June 2023

COVID-19 has had devastating effects on health systems but reports from sub-Saharan Africa are few. We compared inpatient admissions, diagnostic tests performed, clinical characteristics and inpatient mortality before and during the COVID-19 pandemic at an urban tertiary facility in Uganda. We conducted a retrospective chart review of patients admitted at Kiruddu National Referral Hospital in Uganda between January–July 2019 (before the pandemic) and January–July 2020 (during the pandemic). Of 3749 inpatients, 2014 (53.7%) were female, and 1582 (42.2%) had HIV. There was a 6.1% decline in admissions from 1932 in 2019 to 1817 in 2020. There were significantly fewer diagnostic tests performed in 2020 for malaria, tuberculosis, and diabetes. Overall, 649 (17.3%) patients died. Patients admitted during the COVID-19 pandemic (adjusted odds ratio [aOR] 1.2, 95% confidence interval [CI] 1.04–1.5, p = 0.018), patients aged ≥ 60 years (aOR 1.6, 95% CI 1.2–2.1, p = 0.001), HIV co-infected (aOR 1.5, 95% CI 1.2–1.9, p < 0.001), and those admitted as referrals (aOR 1.5, 95% CI 1.2–1.9, p < 0.001) had higher odds of dying. The COVID-19 pandemic disrupted inpatient service utilization and was associated with inpatient mortality. Policy makers need to build resilience in health systems in Africa to cope with future pandemics.
Emerging investigator series: a machine learning approach to quantify the impact of meteorology on tropospheric ozone in the inland southern California
Authors: Do Khanh , Mahish Manasi , Yeganeh Arash Kashfi , Gao Ziqi , Blanchard Charles L. , Ivey Cesunica E.
Published: June 2023

The role of meteorology in facilitating the formation and accumulation of ground-level ozone is of great theoretical and practical interest, especially due to emissions shifts and changing global climate.
Coumarin-functionalized metal–organic frameworks: adsorbents with photo-responsive active sites for adsorptive desulfurization
Authors: Zhu Jing , Qi Shi-Chao , Liu Xiao-Qin , Sun Lin-Bing
Published: June 2023

Under distinct irradiation conditions, controllable processes of adsorptive desulfurization are achieved on coumarin-functionalized adsorbents with photo-responsive active sites.
Local segmental miscibility dominating stereocomplex crystallization in polymer blends
Authors: Zhu Qian , Wen Jianlong , Ma Mingyang , Nie Yijing
Published: June 2023

The influence of segmental miscibility on the formation of stereocomplex crystals, while excluding other relevant factors, was studied for the first time.
Alkaline earth metal ion doping to enhance the light emission from Er3+:SnO2 nanocrystal Co-doped silica films
Authors: Qu Enze , Zhang Yangyi , Wang Lixiang , Chen Jiaming , Li Dongke , Zhao Jingjie , Xu Jun , Chen Kunji
Published: June 2023

The NIR light emission intensities around 1540 nm from Er3+ ions can be obviously enhanced for all alkaline earth metal ion co-doped samples with suitable doping concentrations.
Organic compounds for solid state luminescence enhancement/aggregation induced emission: a theoretical perspective
Authors: Turelli Michele , Ciofini Ilaria , Wang Qinfan , Ottochian Alistar , Labat Frédéric , Adamo Carlo
Published: June 2023

In this perspective, we discuss some major aspects of the current theoretical understanding of solid-state enhanced luminescence (SLE) and we outline a set of general characteristics that many materials expressing this behaviour share.
Poly(3,4-ethylenedioxythiophene) encapsulating hydrated vanadium oxide nanobelts boosts their conductivity and zinc-ion storage properties
Authors: Sun Jingjing , Rong Mengyu , Gao Zhanming , Feng Ziyi , Liu Yanyan , Hu Tao , Meng Changgong , Zhang Yifu
Published: June 2023

A core–shell V2O5·nH2O@poly(3,4-ethylenedioxythiophene) structure was fabricated by wrapping, preventing structural collapse and improving the conductivity.
The central role of translation elongation in response to stress
Authors: Barros Géssica C. , Guerrero Sofia , Silva Gustavo M.
Published: June 2023

Protein synthesis is essential to support homeostasis, and thus, must be highly regulated during cellular response to harmful environments. All stages of translation are susceptible to regulation under stress, however, the mechanisms involved in translation regulation beyond initiation have only begun to be elucidated. Methodological advances enabled critical discoveries on the control of translation elongation, highlighting its important role in translation repression and the synthesis of stress-response proteins. In this article, we discuss recent findings on mechanisms of elongation control mediated by ribosome pausing and collisions and the availability of tRNAs and elongation factors. We also discuss how elongation intersects with distinct modes of translation control, further supporting cellular viability and gene expression reprogramming. Finally, we highlight how several of these pathways are reversibly regulated, emphasizing the dynamics of translation control during stress-response progression. A comprehensive understanding of translation regulation under stress will produce fundamental knowledge of protein dynamics while opening new avenues and strategies to overcome dysregulated protein production and cellular sensitivity to stress.
APPSO‐NN: An adaptive‐probability particle swarm optimization neural network for sensorineural hearing loss detection
Authors: Yang Jingyuan , Zhang Yu‐Dong
Published: June 2023

As a hearing disorder, sensorineural hearing loss (SNHL) can be effectively detected by magnetic resonance imaging (MRI). However, the manual detection of MRI scanning is subjective, time‐consuming, and unpredictable. An accurate and automatic computer‐aided diagnosis system is proposed for SNHL detection, providing reliable references for professionals. The system first employs a wavelet entropy layer to extract features of MRI images. Then, a neural network layer is proposed as the classifier consisting of a feedforward neural network (FNN) and an adaptive‐probability PSO (APPSO) algorithm. The authors prove the rotation‐variant property of the basic particle swarm optimization (PSO) by the algebraic property of matrix transformation. The property is unsuitable for optimising parameters of neural networks. Thus, in APPSO, the authors integrate the new update rules based on all‐dimensional variation and adaptive‐probability mechanism into the basic PSO, which can improve its searching ability without losing population diversity. The authors compare APPSO‐NN with FNN trained by five popular evolutionary algorithms. The simulation results show that APPSO performs best in training FNN. The method also compares with six state‐of‐the‐art methods. The simulation results show that the best performance in sensitivity and overall accuracy of hearing loss classification, which proves that the method is effective and promising for SNHL detection.
Difference analysis of dissolved gas in natural ester insulating fluids under typical electrical and thermal faults: An experimental study
Authors: Xing Yadong , Hu Yizhuo , Ma Yaoxiang , Liu Yang , Dong Ming , Xu Yang
Published: June 2023

Natural ester insulating oil is widely used in transformers due to its good fire resistance and biodegradability. It is mainly composed of triglycerides, and there are some differences in fatty acid composition and content among natural esters. Therefore, the fault diagnosis methods based on dissolved gas analysis are different. Three kinds of natural ester insulating oils are used to study the dissolved gas in oil under typical electrical and thermal faults of power transformers. Thermal faults from 200°C to 800°C and electrical faults with different discharge energies, which include partial discharge, breakdown discharge, and arc discharge, are simulated. The characteristic gases and their variation trends of natural esters under thermal and electrical faults are obtained through the experimental results. The gas generation characteristics of the three natural ester insulating oils under typical electrical and thermal faults are almost similar, but the relative percentages of characteristic gases have certain differences. Natural ester insulating oil with a higher unsaturation degree tends to produce more H2 and less C2H4. Finally, the fault diagnosis methods are used to determine the fault gas data, and the Duval pentagon is modified and improved according to the gas generation characteristics of natural esters.
Simultaneous and panchromatic observations of the fast radio burst FRB 20180916B
Authors: Trudu M. , Pilia M. , Nicastro L. , Guidorzi C. , Orlandini M. , Zampieri L. , Marthi V. R. , Ambrosino F. , Possenti A. , Burgay M. , Casentini C. , Mereminskiy I. , Savchenko V. , Palazzi E. , Panessa F. , Ridolfi A. , Verrecchia F. , Anedda M. , Bernardi G. , Bachetti M. , Burenin R. , Burtovoi A. , Casella P. , Fiori M. , Frontera F. , Gajjar V. , Gardini A. , Ge M. , Guijarro-Román A. , Ghedina A. , Hermelo I. , Jia S. , Li C. , Liao J. , Li X. , Lu F. , Lutovinov A. , Naletto G. , Ochner P. , Papitto A. , Perri M. , Pittori C. , Safonov B. , Semena A. , Strakhov I. , Tavani M. , Ursi A. , Xiong S. L. , Zhang S. N. , Zheltoukhov S.
Published: June 2023

Aims.Fast radio bursts are bright radio transients whose origins are not yet understood. The search for a multi-wavelength counterpart of those events can set a tight constraint on the emission mechanism and the progenitor source.

Methods.We conducted a multi-wavelength observational campaign on FRB 20180916B between October 2020 and August 2021 over eight activity cycles of the source. Observations were carried out in the radio band by the SRT both at 336 and 1547 MHz and the uGMRT at 400 MHz. Simultaneous observations were conducted by the optical telescopes Asiago (GalileoandCopernico), CMO SAI MSU, CAHA 2.2 m, RTT-150 and TNG, and X/γ-ray detectors on board the AGILE,Insight–HXMT, INTEGRAL, andSwiftsatellites.

Results.We present the detection of 14 new radio bursts detected with the SRT at 336 MHz and seven new bursts with the uGMRT from this source. We provide the deepest prompt upper limits in the optical band for FRB 20180916B to date. In fact, the TNG/SiFAP2 observation simultaneous to a burst detection by uGMRT gives an upper limitEoptical/Eradio <  1.3 × 102. Another burst detected by the SRT at 336 MHz was also co-observed byInsight–HXMT. The non-detection in the X-rays yields an upper limit (1 − 30 keV band) ofEX − ray/Eradioin the range of (0.9 − 1.3) × 107, depending on the model that is considered for the X-ray emission.
A descent scaled conjugate gradient method for unconstrained optimization with its applications in image restoration problems
Authors: Lotfi Mina , Hosseini Seyed Mohammad
Published: June 2023

Based on combining the conjugate gradient method proposed by Hager and Zhang with the scaled gradient idea, we presented a new scaled conjugate gradient method which satisfies the sufficient descent condition. In our method, the scaled parameter is determined so that the search direction becomes close to the three-term HS method suggested by Zhang, Zhou and Li. It is proved that the new method is globally convergent for general nonlinear functions, under some standard assumptions. Numerical comparisons on some test problems from the CUTEst library and image restoration problems illustrate the efficiency and robustness of our proposed method in practice.
Beurteilung der Sakroiliitis mittels künstlicher Intelligenz
– Fortschritte und Limitationen
Authors: Adams Lisa , Vahldiek Janis L. , Poddubnyy Denis , Bressem Keno
Published: June 2023

Die Sakroiliitis ist eine entzündliche Erkrankung des
Sakroiliakalgelenks, die durch Faktoren wie Infektionen, Traumata und
Autoimmunerkrankungen ausgelöst werden kann. Sie verursacht Schmerzen
und Steifheit im unteren Rücken, weshalb eine frühzeitige
Diagnose für eine optimale Behandlung entscheidend ist. Die Diagnose ist
anspruchsvoll und erfordert klinische Beurteilung, Labortests und bildgebende
Verfahren wie Röntgen, MRT oder CT. In den letzten Jahren hat sich die
künstliche Intelligenz (KI) als vielversprechendes Instrument
für die Beurteilung von Veränderungen im Rahmen der Sakroiliitis
herausgestellt. KI-Algorithmen analysieren verschiedene bildgebende Verfahren,
um strukturelle Veränderungen und Entzündungen im
Sakroiliakalgelenk zu erkennen, zu quantifizieren und einzuordnen. Die Anwendung
von KI kann die Diagnosegenauigkeit und Effizienz des Radiologen bzw. des
Rheumatologen bei der Beurteilung von Sakroiliitis durch bildgebende Verfahren
verbessern. KI-Algorithmen können strukturelle Veränderungen und
Entzündungen im Sakroiliakalgelenk quantifizieren und Vorhersagemodelle
für den Krankheitsverlauf erstellen. Herausforderungen wie der Bedarf an
qualitativ hochwertigen Daten und die Minimierung von Verzerrungen und Fehlern
in den Daten und Algorithmen müssen jedoch bewältigt werden.
Weitere Studien sind erforderlich, um das volle Potenzial der KI bei der
Beurteilung von Sakroiliitis auszuschöpfen. Der Einsatz von KI kann
jedoch die Ergebnisse für Patienten verbessern, indem er eine
frühzeitige Diagnose und Behandlung ermöglicht.
Chapman–Jouguet deflagration criteria and compressibility dynamics of turbulent fast flames for turbulence-induced deflagration-to-detonation transition
Authors: Chin Hardeo , Chambers Jessica , Poludnenko Alexei , Gamezo Vadim N. , Ahmed Kareem A.
Published: June 2023

This work characterizes the compressibility dynamics in turbulent fast flames for a range of turbulent flame speeds. These turbulent fast flames experience increased effects of compressibility through the formation of strong shocks and may develop a runaway acceleration combined with a pressure buildup that leads to turbulence induced deflagration-to-detonation transition (tDDT). Simultaneous high-speed particle image velocimetry, OH* chemiluminescence, schlieren, and pressure measurements are used to examine the reacting flow field and flame dynamics. We examine flames with turbulent flame speeds ranging from 100 to 600 m/s. At lower turbulent flame speeds, the flame is not able to produce favorable background conditions for deflagration-to-detonation transition (DDT) onset, and thus flame compressibility and turbulence amplification are less dominant, resulting in a weaker acoustic coupling between the flame and compressed region. As the turbulent burning velocities exceed the Chapman–Jouguet deflagration speed, favorable background conditions are produced, as we observe flame-generated shocks and flame-generated turbulence with higher turbulent velocities and larger turbulent scales. At this regime, the flame is categorized to be at the runaway transition regime that leads to tDDT.
Improving the stability of temporal statistics in transition path theory with sparse data
Authors: Bonner Gage , Beron-Vera F. J. , Olascoaga M. J.
Published: June 2023

Ulam’s method is a popular discretization scheme for stochastic operators that involves the construction of a transition probability matrix controlling a Markov chain on a set of cells covering some domain. We consider an application to satellite-tracked undrogued surface-ocean drifting buoy trajectories obtained from the National Oceanic and Atmospheric Administration Global Drifter Program dataset. Motivated by the motion of Sargassum in the tropical Atlantic, we apply Transition Path Theory (TPT) to drifters originating off the west coast of Africa to the Gulf of Mexico. We find that the most common case of a regular covering by equal longitude–latitude side cells can lead to a large instability in the computed transition times as a function of the number of cells used. We propose a different covering based on a clustering of the trajectory data that is stable against the number of cells in the covering. We also propose a generalization of the standard transition time statistic of TPT that can be used to construct a partition of the domain of interest into weakly dynamically connected regions.
Sensitive dynamics of brain cognitive networks and its resource constraints
Authors: Chen Dehua , Yang Zhiyin , Xiao Qin , Liu Zonghua
Published: June 2023

It is well known that brain functions are closely related to the synchronization of brain networks, but the underlying mechanisms are still not completely understood. To study this problem, we here focus on the synchronization of cognitive networks, in contrast to that of a global brain network, as individual brain functions are in fact performed by different cognitive networks but not the global network. In detail, we consider four different levels of brain networks and two approaches, i.e., either with or without resource constraints. For the case of without resource constraints, we find that global brain networks have fundamentally different behaviors from that of the cognitive networks; i.e., the former has a continuous synchronization transition, while the latter shows a novel transition of oscillatory synchronization. This feature of oscillation comes from the sparse links among the communities of cognitive networks, resulting in coupling sensitive dynamics of brain cognitive networks. While for the case of resource constraints, we find that at the global level, the synchronization transition becomes explosive, in contrast to the continuous synchronization for the case of without resource constraints. At the level of cognitive networks, the transition also becomes explosive and the coupling sensitivity is significantly reduced, thus guaranteeing the robustness and fast switch of brain functions. Moreover, a brief theoretical analysis is provided.
Topological transmission of elastic waves on a macroscopic pentamode metamaterial plate
Authors: Cai Chengxin , He Guangchen , Yin Yuhang , Qin Yao , Chen Huanyang
Published: June 2023

In this paper, we devise a pentamode metamaterial plate exhibiting topological characteristics. By organizing pentamode metamaterial structural elements, topological boundary states are attained, effectively safeguarding propagation of elastic waves. Moreover, based on the numerical simulation model, we employ a polymer to fabricate a macro-scale specimen via additive manufacturing. Through assessing the vibrational response of the sample, we corroborate its topological attributes in governing elastic wave transmission. This discovery paves the way for a novel approach to manipulating acoustic/elastic waves employing pentamode metamaterials.
Using classifiers to understand coarse-grained models and their fidelity with the underlying all-atom systems
Authors: Durumeric Aleksander E. P. , Voth Gregory A.
Published: June 2023

Bottom-up coarse-grained (CG) molecular dynamics models are parameterized using complex effective Hamiltonians. These models are typically optimized to approximate high dimensional data from atomistic simulations. However, human validation of these models is often limited to low dimensional statistics that do not necessarily differentiate between the CG model and said atomistic simulations. We propose that classification can be used to variationally estimate high dimensional error and that explainable machine learning can help convey this information to scientists. This approach is demonstrated using Shapley additive explanations and two CG protein models. This framework may also be valuable for ascertaining whether allosteric effects at the atomistic level are accurately propagated to a CG model.
On the anisotropic weak magnetic field effect in radical-pair reactions
Authors: Luo Jiate
Published: June 2023

For more than 60 years, scientists have been fascinated by the fact that magnetic fields even weaker than internal hyperfine fields can markedly affect spin-selective radical-pair reactions. This weak magnetic field effect has been found to arise from the removal of degeneracies in the zero-field spin Hamiltonian. Here, I investigated the anisotropic effect of a weak magnetic field on a model radical pair with an axially symmetric hyperfine interaction. I found that S–T± and T0–T± interconversions driven by the smaller x and y-components of the hyperfine interaction can be hindered or enhanced by a weak external magnetic field, depending on its direction. Additional isotropically hyperfine-coupled nuclear spins preserve this conclusion, although the S → T± and T0 → T± transitions become asymmetric. These results are supported by simulating reaction yields of a more biologically plausible, flavin-based radical pair.
Accurate determination of band tail properties in amorphous semiconductor thin film with Kelvin probe force microscopy
Authors: Fabbri Luca , Bordoni Camilla , Barquinha Pedro , Crocco Jerome , Fraboni Beatrice , Cramer Tobias
Published: June 2023

The disordered microscopic structure of amorphous semiconductors causes the formation of band tails in the density of states (DOS) that strongly affect charge transport properties. Such band tail properties are crucial for understanding and optimizing thin-film device performance with immense relevance for large area electronics. Among the available techniques to measure the DOS, Kelvin Probe Force Microscopy (KPFM) is exceptional as it enables precise local electronic investigations combined with microscopic imaging. However, a model to interpret KPFM spectroscopy data on amorphous semiconductors of finite thickness is lacking. To address this issue, we provide an analytical solution to the Poisson equation for a metal–insulator–semiconductor junction interacting with the atomic force microscope tip. The solution enables us to fit experimental data for semiconductors with finite thickness and to obtain DOS parameters, such as band tail width, doping density, and flat band potential. To demonstrate our method, we perform KPFM experiments on Indium–Gallium–Zinc Oxide (IGZO) thin-film transistors (IGZO-TFTs). DOS parameters compare well with values obtained with photocurrent spectroscopy. We demonstrate the relevance of the developed method by investigating the impact of ionizing radiation on DOS parameters and TFT performance. Our results provide clear evidence that the observed shift in threshold voltage is caused by static charge in the gate dielectric, leading to a shift in flat band potential. Band-tails and doping density are not affected by the radiation. The developed methodology can be easily translated to different semiconductor materials and paves the way for quantitative microscopic mapping of local DOS parameters in thin-film devices.
Scaling properties of RNA as a randomly branching polymer
Authors: Vaupotič Domen , Rosa Angelo , Tubiana Luca , Božič Anže
Published: June 2023

Formation of base pairs between the nucleotides of a ribonucleic acid (RNA) sequence gives rise to a complex and often highly branched RNA structure. While numerous studies have demonstrated the functional importance of the high degree of RNA branching—for instance, for its spatial compactness or interaction with other biological macromolecules—RNA branching topology remains largely unexplored. Here, we use the theory of randomly branching polymers to explore the scaling properties of RNAs by mapping their secondary structures onto planar tree graphs. Focusing on random RNA sequences of varying lengths, we determine the two scaling exponents related to their topology of branching. Our results indicate that ensembles of RNA secondary structures are characterized by annealed random branching and scale similarly to self-avoiding trees in three dimensions. We further show that the obtained scaling exponents are robust upon changes in nucleotide composition, tree topology, and folding energy parameters. Finally, in order to apply the theory of branching polymers to biological RNAs, whose length cannot be arbitrarily varied, we demonstrate how both scaling exponents can be obtained from distributions of the related topological quantities of individual RNA molecules with fixed length. In this way, we establish a framework to study the branching properties of RNA and compare them to other known classes of branched polymers. By understanding the scaling properties of RNA related to its branching structure, we aim to improve our understanding of the underlying principles and open up the possibility to design RNA sequences with desired topological properties.
Benchmark coupled-cluster lattice energy of crystalline benzene and assessment of multi-level approximations in the many-body expansion
Authors: Borca Carlos H. , Glick Zachary L. , Metcalf Derek P. , Burns Lori A. , Sherrill C. David
Published: June 2023

The many-body expansion (MBE) is promising for the efficient, parallel computation of lattice energies in organic crystals. Very high accuracy should be achievable by employing coupled-cluster singles, doubles, and perturbative triples at the complete basis set limit [CCSD(T)/CBS] for the dimers, trimers, and potentially tetramers resulting from the MBE, but such a brute-force approach seems impractical for crystals of all but the smallest molecules. Here, we investigate hybrid or multi-level approaches that employ CCSD(T)/CBS only for the closest dimers and trimers and utilize much faster methods like Møller–Plesset perturbation theory (MP2) for more distant dimers and trimers. For trimers, MP2 is supplemented with the Axilrod–Teller–Muto (ATM) model of three-body dispersion. MP2(+ATM) is shown to be a very effective replacement for CCSD(T)/CBS for all but the closest dimers and trimers. A limited investigation of tetramers using CCSD(T)/CBS suggests that the four-body contribution is entirely negligible. The large set of CCSD(T)/CBS dimer and trimer data should be valuable in benchmarking approximate methods for molecular crystals and allows us to see that a literature estimate of the core-valence contribution of the closest dimers to the lattice energy using just MP2 was overbinding by 0.5 kJ mol−1, and an estimate of the three-body contribution from the closest trimers using the T0 approximation in local CCSD(T) was underbinding by 0.7 kJ mol−1. Our CCSD(T)/CBS best estimate of the 0 K lattice energy is −54.01 kJ mol−1, compared to an estimated experimental value of −55.3 ± 2.2 kJ mol−1.
The impact of climate change and wildfire on decadal alpine vegetation dynamics
Authors: Verrall Brodie , Norman Patrick , Mackey Brendan , Fisher Scout , Dodd Jack
Published: June 2023

Context Climate-induced changes of alpine vegetation diversity, cover and composition have been recorded globally, but most insights have been gleaned from field studies over small spatiotemporal scales. Aims We assess dynamics in climate and vegetation of Australia’s highest and most biologically diverse alpine area that surrounds Mount Kosciuszko (~455 km2), as well as recovery following the 2003 wildfires. Methods Climatic changes were analysed using gridded climate data for mean annual temperature (1910–2019) and seasonal precipitation (1900–2019), and changes in snow cover were assessed from snow course records (1954–2021). A vegetation cover time series (1990, 2000, 2010, 2020) was modelled with an optimised random forest classification using recursive feature selection, and the LandTrendr algorithm was used to detect areas burnt during wildfires. Key results Over time, temperatures and summer precipitation increased, whereas snow cover and winter precipitation decreased. Subsequently, vegetation dynamics were dominated by the densification of subalpine woodlands at lower elevations, replacing dry and wet heathlands. There was treeline stasis but upslope advancement of dry and wet shrublines but grassland vegetation types were relatively stable. However, in burnt areas there was suppressed upslope advancement of shrublines, treeline recession and relatively less expansion of subalpine woodlands. Conclusions Alpine vegetation may be impacted by climate change incrementally through relatively gradual changes in climatic conditions, and transformatively through landscape-level disturbance from wildfires. Implications Higher temperatures and altered precipitation regimes increase the frequency and severity of wildfires, which may be amplified by increasing fuel loads and dryness from the proliferation and advance of woody vegetation in alpine areas.