bluuebunny/crossref_metadata_2025 huggingface dataset:
Observations and Analysis of CH+ Vibrational Emissions from the Young, Carbon-rich Planetary Nebula NGC 7027: A Textbook Example of Chemical Pumping
Authors: Neufeld David A. , Godard Benjamin , Bryan Changala P. , Faure Alexandre , Geballe T. R. , Güsten Rolf , Menten Karl M. , Wiesemeyer Helmut
Published: August 2021

We discuss the detection of 14 rovibrational lines of CH+, obtained toward the planetary nebula NGC 7027 with the iSHELL spectrograph on NASA’s Infrared Telescope Facility (IRTF) on Maunakea. Our observations in the 3.49–4.13 μm spectral region, obtained with a 0.″375 slit width that provided a spectral resolving power λ/Δλ ∼ 80,000, have resulted in the unequivocal detection of the R(0)−R(3) and P(1)−P(10) transitions within the v = 1−0 band of CH+. The R-branch transitions are anomalously weak relative to the P-branch transitions, a behavior that is explained accurately by rovibronic calculations of the transition dipole moment reported in a companion paper. Nine infrared transitions of H2 were also detected in these observations, comprising the S(8), S(9), S(13), and S(15) pure rotational lines; the v = 1−0 O(4)−O(7) lines; and the v = 2−1 O(5) line. We present a photodissociation model, constrained by the CH+ and H2 line fluxes that we measured, that includes a detailed treatment of the excitation of CH+ by inelastic collisions, optical pumping, and chemical (“formation”) pumping. The latter process is found to dominate the excitation of the observed rovibrational lines of CH+, and the model is remarkably successful in explaining both the absolute and relative strengths of the CH+ and H2 lines.
Evidence for Radial Expansion at the Core of the Orion Complex with Gaia EDR3
Authors: Swiggum Cameren , D’Onghia Elena , Alves João , Großschedl Josefa , Foley Michael , Zucker Catherine , Meingast Stefan , Chen Boquan , Goodman Alyssa
Published: August 2021

We present a phase-space study of two stellar groups located at the core of the Orion Complex: Briceño-1 and Orion Belt Population-near (OBP-near). We identify the groups with the unsupervised clustering algorithm, Shared Nearest Neighbor (SNN), which previously identified 12 new stellar substructures in the Orion Complex. For each of the two groups, we derive the 3D space motions of individual stars using Gaia EDR3 proper motions supplemented by radial velocities from Gaia DR2, APOGEE-2, and GALAH DR3. We present evidence for radial expansion of the two groups from a common center. Unlike previous work, our study suggests that evidence of stellar group expansion is confined only to OBP-near and Briceño-1, whereas the rest of the groups in the complex show more complicated motions. Interestingly, the stars in the two groups lie at the center of a dust shell, as revealed via an extant 3D dust map. The exact mechanism that produces such coherent motions remains unclear, while the observed radial expansion and dust shell suggest that massive stellar feedback could have influenced the star formation history of these groups.
Evidence Suggesting That ‘Oumuamua Is the ∼30 Myr Old Product of a Molecular Cloud
Authors: Hsieh Cheng-Han , Laughlin Gregory , Arce Héctor G.
Published: August 2021

The appearance of interstellar objects (ISOs) in the solar system—and specifically the arrival of 1I/‘Oumuamua—points to a significant number density of free-floating bodies in the solar neighborhood. We review the details of ‘Oumuamua’s pre-encounter Galactic orbit, which intersected the solar system at very nearly its maximum vertical and radial excursion relative to the Galactic plane. These kinematic features are strongly emblematic of nearby young stellar associations. We obtain an a priori order-of-magnitude age estimate for ‘Oumuamua by comparing its orbit to the orbits of 50,899 F-type stars drawn from Gaia DR2; a diffusion model then suggests a ∼35 Myr dynamical age. We compare ‘Oumuamua’s orbit with the trajectories of individual nearby moving groups, confirming that its motion is fully consistent with membership in the Carina (CAR) moving group with an age of ~30 Myr. We conduct Monte Carlo simulations that trace the orbits of test particles ejected from the stars in the CAR association. The simulations indicate that in order to uniformly populate the ∼106 pc3 volume occupied by CAR members with the inferred number density, n = 0.2 au−3, of ISOs implied by Pan-STARRS’s detection of ‘Oumuamua, the required ejection mass is M ∼ 500 M
Jup per known star within the CAR association. This suggests that the Pan-STARRS observation is in significant tension with scenarios that posit ‘Oumuamua’s formation and ejection from a protostellar disk.
The Palomar Transient Factory Core-collapse Supernova Host-galaxy Sample. I. Host-galaxy Distribution Functions and Environment Dependence of Core-collapse Supernovae
Authors: Schulze Steve , Yaron Ofer , Sollerman Jesper , Leloudas Giorgos , Gal Amit , Wright Angus H. , Lunnan Ragnhild , Gal-Yam Avishay , Ofek Eran O. , Perley Daniel A. , Filippenko Alexei V. , Kasliwal Mansi M. , Kulkarni Shrinivas R. , Neill James D. , Nugent Peter E. , Quimby Robert M. , Sullivan Mark , Strotjohann Nora Linn , Arcavi Iair , Ben-Ami Sagi , Bianco Federica , Bloom Joshua S. , De Kishalay , Fraser Morgan , Fremling Christoffer U. , Horesh Assaf , Johansson Joel , Kelly Patrick L. , Knežević Nikola , Knežević Sladjana , Maguire Kate , Nyholm Anders , Papadogiannakis Seméli , Petrushevska Tanja , Rubin Adam , Yan Lin , Yang Yi , Adams Scott M. , Bufano Filomena , Clubb Kelsey I. , Foley Ryan J. , Green Yoav , Harmanen Jussi , Ho Anna Y. Q. , Hook Isobel M. , Hosseinzadeh Griffin , Howell D. Andrew , Kong Albert K. H. , Kotak Rubina , Matheson Thomas , McCully Curtis , Milisavljevic Dan , Pan Yen-Chen , Poznanski Dovi , Shivvers Isaac , van Velzen Sjoert , Verbeek Kars K.
Published: August 2021

Several thousand core-collapse supernovae (CCSNe) of different flavors have been discovered so far. However, identifying their progenitors has remained an outstanding open question in astrophysics. Studies of SN host galaxies have proven to be powerful in providing constraints on the progenitor populations. In this paper, we present all CCSNe detected between 2009 and 2017 by the Palomar Transient Factory. This sample includes 888 SNe of 12 distinct classes out to redshift z ≈ 1. We present the photometric properties of their host galaxies from the far-ultraviolet to the mid-infrared and model the host-galaxy spectral energy distributions to derive physical properties. The galaxy mass function of Type Ic, Ib, IIb, II, and IIn SNe ranges from 105 to 1011.5
M
⊙, probing the entire mass range of star-forming galaxies down to the least-massive star-forming galaxies known. Moreover, the galaxy mass distributions are consistent with models of star-formation-weighted mass functions. Regular CCSNe are hence direct tracers of star formation. Small but notable differences exist between some of the SN classes. Type Ib/c SNe prefer galaxies with slightly higher masses (i.e., higher metallicities) and star formation rates than Type IIb and II SNe. These differences are less pronounced than previously thought. H-poor superluminous supernovae (SLSNe) and SNe Ic-BL are scarce in galaxies above 1010
M
⊙. Their progenitors require environments with metallicities of < 0.4 and < 1 solar, respectively. In addition, the hosts of H-poor SLSNe are dominated by a younger stellar population than all other classes of CCSNe. Our findings corroborate the notion that low metallicity and young age play an important role in the formation of SLSN progenitors.
Evolution of Cold Gas at 2 < z < 5: A Blind Search for H i and OH Absorption Lines toward Mid-infrared Color-selected Radio-loud AGN
Authors: Gupta N. , Srianand R. , Shukla G. , Krogager J-. K. , Noterdaeme P. , Combes F. , Dutta R. , Fynbo J. P. U. , Hilton M. , Momjian E. , Moodley K. , Petitjean P.
Published: August 2021

We present results from a spectroscopically blind search for associated and intervening H i 21 cm and OH 18 cm absorption lines toward 88 active galactic nuclei (AGN) at 2 ≤ z ≤ 5 using the uGMRT. The sample of AGN with 1.4 GHz spectral luminosity in the range 1027−29.3 W Hz−1 is selected using mid-infrared colors and closely resembles the distribution of the underlying quasar population. The search for associated or proximate absorption, defined to be within 3000 km s−1 of the AGN redshift, led to one H i 21 cm absorption detection (M1540−1453; z
abs = 2.1139). This is only the fourth known absorption at z > 2. The detection rate (

1.6

−
1.4

+
3.8

%) suggests a low covering factor of the cold neutral medium (CNM; T ∼ 100 K) associated with these powerful AGN. The intervening absorption line search, with a sensitivity to detect the CNM in damped Lyα systems (DLAs), has comoving absorption path lengths of ΔX = 130.1 and 167.7 for H i and OH, respectively. The corresponding number of absorbers per unit comoving path length are ≤0.014 and ≤0.011, respectively. The former is at least 4.5 times lower than that of DLAs and consistent with the CNM cross section estimated using H2 and C i absorbers at z > 2. Our AGN sample is optically fainter compared to the quasars used to search for DLAs in the past. In our optical spectra obtained using SALT and NOT, we detect five intervening (redshift path ∼9.3) and two proximate DLAs. This is slightly excessive compared to the statistics based on optically selected quasars. The nondetection of H i 21 cm absorption from these DLAs suggests a small CNM covering fraction around galaxies at z > 2.
Atomic Transition Probabilities of Neutral Calcium*
Authors: Den Hartog E. A. , Lawler J. E. , Sneden C. , Cowan J. J. , Roederer I. U. , Sobeck J.
Published: August 2021

The goals of this study are (1) to test the best theoretical transition probabilities for Ca i (a relatively light alkaline earth spectrum) from a modern ab initio calculation using configuration interaction plus many-body perturbation theory against the best modern experimental transition probabilities and (2) to produce as accurate and comprehensive a line list of Ca i transition probabilities as is currently possible based on this comparison. We report new Ca i radiative lifetime measurements from a laser-induced fluorescence experiment and new emission branching fraction measurements from a 0.5 m focal length grating spectrometer with a detector array. We combine these data for upper levels that have both a new lifetime and new branching fractions to report log(gf) values for two multiplets consisting of nine transitions. Detailed comparisons are made between theory and experiment, including the measurements reported herein and a selected set of previously published experimental transition probabilities. We find that modern theory compares favorably to experimental measurements in most instances where such data exist. A final list of 202 recommended transition probabilities is presented, which covers lines of Ca i with wavelengths ranging from 2200 to 10000 Å. These are mostly selected from theory but are augmented with high-quality experimental measurements from this work and from the literature. The recommended transition probabilities are used in a redetermination of the Ca abundance in the Sun and in the metal-poor star HD 84937.
A Recipe for the Geophysical Exploration of Enceladus
Authors: Ermakov Anton I. , Park Ryan S. , Roa Javier , Castillo-Rogez Julie C. , Keane James T. , Nimmo Francis , Kite Edwin S. , Sotin Christophe , Lazio T. Joseph W. , Steinbrügge Gregor , Howell Samuel M. , Bills Bruce G. , Hemingway Douglas J. , Viswanathan Vishnu , Tobie Gabriel , Lainey Valery
Published: August 2021

Orbital geophysical investigations of Enceladus are critical to understanding its energy budget. In this paper, we identified key science questions for the geophysical exploration of Enceladus, answering which would support future assessment of Enceladus’ astrobiological potential. Using a Bayesian framework, we explored how science requirements map to measurement requirements. We performed mission simulations to study the sensitivity of single-spacecraft and dual-spacecraft configurations to static gravity and tidal Love numbers of Enceladus. We find that mapping Enceladus’ gravity field, improving the accuracy of the physical libration amplitude, and measuring Enceladus’ tidal response would provide critical constraints on the internal structure and establish a framework for assessing Enceladus’ long-term habitability. This kind of investigation could be carried out as part of a life search mission at little additional resource requirements.
The Pyrenean species of Chelidura (Dermaptera, Forficulidae)
Authors: Jurado-Angulo Pilar , Jiménez-Ruiz Yolanda , García-París Mario
Published: August 2021

The Pyrenees are inhabited by scattered populations of earwigs of the genusCheliduraLatreille, 1825. There is some controversy about the specific assignment of these populations: while most authors assign them toC. pyrenaica(Gené, 1832), other consider thatC. aptera(Mégerlé, 1825) is also present in the Pyrenees. The main objective of this work was to revise the identity and synonyms of PyreneanChelidura. Specimens from recent fieldwork and collections (MNCN-CSIC) were used for morphological and molecular studies (cytochrome oxidase 1). All Pyrenean specimens shared similarcox1sequences, very divergent from those of AlpineC. aptera. As a consequence, the variability observed in male cerci morphology from the Pyrenees, ranging from long and slightly curved to short and very curved, corresponded toC. pyrenaica, and the presence ofC. apterain the Pyrenees can be rejected. As previously suggested by Maccagno (1933) and Fontana et al. (2021), the revision of the synonymic list uncovered the misplacement of the nameF. simplexGermar, 1825 under the synonymy ofC. aptera, while it rather represents a synonym ofC. pyrenaica(syn. nov.).Forficula simplexhas nomenclatural priority overC. pyrenaica, however both names meet the requirements of the article 23.9.1 of the International Code of Zoological Nomenclature to retain the prevailing usage ofC. pyrenaica(nomen protectum) overF. simplex(nomen oblitum). Additionally, we discuss the taxonomic status ofChelidura arvernaDavid & Van Herrewege, 1973stat. nov.from the French Massif Central.
A type catalogue of the reed frogs (Amphibia, Anura, Hyperoliidae) in the collection of the Museum für Naturkunde Berlin (ZMB) with comments on historical collectors and expeditions
Authors: Tillack Frank , de Ruiter Ronald , Rödel Mark-Oliver
Published: August 2021

We present a commented catalogue of the type specimens of the Afro-Malagasy frog family Hyperoliidae at the herpetological collection of the Museum für Naturkunde Berlin (ZMB). In current publications and databases, many names based on ZMB primary types are listed as synonyms of other species, the types often declared as lost. Consequently, the respective names are often no longer considered in current taxonomic work. We traced 146 nominal taxa of the family Hyperoliidae in the ZMB collection of which currently 130 are presented by primary types (88 holotypes, 10 lectotypes and 32 taxa based on syntype series); 50 of these taxa are currently considered as valid. Primary types of nine taxa could not be located during our inventory of the collection holdings. Seven taxa are exclusively represented by secondary types (paratypes). Many of these types comprise taxa where types have been thought to be lost. As a further service to the community, we provide important details about collectors and their travel routes, as well as respective documents stored in the collection of the Department of Historical Research at ZMB. This should make it easier to potentially compare the ZMB types in future taxonomic revisions.
La propagande allemande par le livre
Authors: Puren Marie
Published: August 2021

Entre 1941 et 1944, les éditions Ferenczi ont été sous contrôle allemand. « Aryanisées » et dirigées par un administrateur complaisant, elles ont été mises au service des desseins allemands, avec pour objectif de convertir les Français à la collaboration. L’histoire de cette maison d’édition pendant la guerre offre un aperçu complet des mesures utilisées par les occupants pour pénétrer et contrôler l’édition française et pour diffuser leur matériel de propagande. Mais les résultats ne semblent pas avoir été à la hauteur des efforts investis. Cet article tente de comprendre quelles ont été les raisons de cet échec, et plus globalement de celui de la propagande allemande par le livre, en examinant le fonctionnement de ces maisons d’éditions.
La promotion d’une érudition locale comme expertise
Authors: Garnier Gautier
Published: August 2021

Cet article analyse la conversion d’une tradition d’érudition locale sur la ville de Lisbonne (« l’olisipographie ») en expertise tournée vers l’action municipale, entre les années 1930 et la décennie 1950. Ce phénomène est rendu possible par la fermeture sociopolitique de la municipalité lisboète (CML) sous l’Estado Novo salazariste. La CML contribue à l’institutionnalisation de l’olisipographie tandis que cette dernière lui fournit un ensemble de savoirs sur la ville. Les olisipographes sont portés par un groupement de notables (le Grupo Amigos de Lisboa) qui se pose en interprète des intérêts des Lisboètes. S’ils s’affirment comme des mémoriens, c’est-à-dire des experts en mémoire, ils échouent toutefois à faire prévaloir leurs idées en matière d’urbanisme.
Feedback particle filter for collective inference
Authors: Kim Jin-Won , Taghvaei Amirhossein , Chen Yongxin , Mehta Prashant G.
Published: August 2021

The purpose of this paper is to describe the feedback particle filter algorithm for problems where there are a large number (\begin{document}$ M $\end{document}) of non-interacting agents (targets) with a large number (\begin{document}$ M $\end{document}) of non-agent specific observations (measurements) that originate from these agents. In its basic form, the problem is characterized by data association uncertainty whereby the association between the observations and agents must be deduced in addition to the agent state. In this paper, the large-\begin{document}$ M $\end{document} limit is interpreted as a problem of collective inference. This viewpoint is used to derive the equation for the empirical distribution of the hidden agent states. A feedback particle filter (FPF) algorithm for this problem is presented and illustrated via numerical simulations. Results are presented for the Euclidean and the finite state-space cases, both in continuous-time settings. The classical FPF algorithm is shown to be the special case (with \begin{document}$ M = 1 $\end{document}) of these more general results. The simulations help show that the algorithm well approximates the empirical distribution of the hidden states for large \begin{document}$ M $\end{document}.
Proof of a Dwork-type supercongruence by induction
Authors: Zhang Yong ,   Department of Mathematics and Physics, Nanjing Institute of Technology, Nanjing 211167, China, Yuan Peisen ,   College of Artificial Intelligence, Nanjing Agricultural University, Nanjing 210095, China
Published: August 2021

In this paper we prove a Dwork-type supercongruence: for any prime $ p\geq3 $ and integer $ r\geq 1 $,

   \begin{document}$ \begin{align*} \sum\limits_{k = 0}^{p^r-1}\frac{3k+1}{16^k}{\binom{2k}{k}}^3\equiv p\sum\limits_{k = 0}^{p^{r-1}-1}\frac{3k+1}{16^k}{\binom{2k}{k}}^3\pmod{p^{3r+1-\delta_{p, 3}}}, \end{align*} $\end{document}

which extends a result of Guo and Zudilin.
Construction of a prognostic model for lung squamous cell carcinoma based on seven N6-methylandenosine-related autophagy genes
Authors: Yu Xin ,   Department of Thoracic Surgery, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital & Shenzhen Hospital, Chinese Academy of Medical Sciences and PeKing Union Medical College, Shenzhen 518116, China, Liu Jun , Xie Ruiwen , Chang Mengling , Xu Bichun , Zhu Yangqing , Xie Yuancai , Yang Shengli ,   Department of Chemotherapy, Affiliated Hospital of Nantong University, Nantong 226001, China,   Department of Cardiothoracic Surgery, Dongguan People's Hospital, Dongguan, Guangzhou 523000, China,   Department of Oncology Radiotherapy, The Second Affiliated Hospital of Soochow University, Suzhou 215000, China,   Department of Thoracic Surgery, Peking University Shenzhen Hospital, Shenzhen 518036, China,   Department of Thoracic Surgery, Foshan First people's Hospital, Affiliated Hospital of Sun Yat sen University, Foshan 528000, China
Published: August 2021

Objective

We aimed to construct a novel prognostic model based on N6-methyladenosine (m6A)-related autophagy genes for predicting the prognosis of lung squamous cell carcinoma (LUSC).

Methods

Gene expression profiles and clinical information of Patients with LUSC were downloaded from The Cancer Genome Atlas (TCGA) database. In addition, m6A- and autophagy-related gene profiles were obtained from TCGA and Human Autophagy Database, respectively. Pearson correlation analysis was performed to identify the m6A-related autophagy genes, and univariate Cox regression analysis was conducted to screen for genes associated with prognosis. Based on these genes, LASSO Cox regression analysis was used to construct a prognostic model. The corresponding prognostic score (PS) was calculated, and patients with LUSC were assigned to low- and high-risk groups according to the median PS value. An independent dataset (GSE37745) was used to validate the prognostic ability of the model. CIBERSORT was used to calculate the differences in immune cell infiltration between the high- and low-risk groups.

Results

Seven m6A-related autophagy genes were screened to construct a prognostic model: CASP4, CDKN1A, DLC1, ITGB1, PINK1, TP63, and EIF4EBP1. In the training and validation sets, patients in the high-risk group had worse survival times than those in the low-risk group; the areas under the receiver operating characteristic curves were 0.958 and 0.759, respectively. There were differences in m6A levels and immune cell infiltration between the high- and low-risk groups.

Conclusions

Our prognostic model of the seven m6A-related autophagy genes had significant predictive value for LUSC; thus, these genes may serve as autophagy-related therapeutic targets in clinical practice.
Academic and non-academic life stressors and their impact on psychological wellbeing of medical students
Authors: Mirza Ahmad A ,   Department of Otolaryngology, Head and Neck Surgery, Faculty of Medicine in Rabigh, King Abdulaziz University, Jeddah, Saudi Arabia, Baarimah Hammam , Baig Mukhtiar , Mirza Abdulrahim A , Halawani Mohammed A , Beyari Ghada M , AlRaddadi Khalid S , Alreefi Mahmoud ,   Psychiatrist, Makkah Healthcare Cluster, Ministry of Health, Saudi Arabia,   Department of Clinical Biochemistry/Medical Education, Faculty of Medicine, Rabigh, King Abdulaziz University, Jeddah, Saudi Arabia,   Department of Surgery, Division of Urology, Ministry of National Guard - Health Affairs, Jeddah, Saudi Arabia,   Faculty of Medicine, Umm Al-Qura University, Makkah, Saudi Arabia,   Faculty of Medicine, Umm Al-Qura University, Makkah, Saudi Arabia,   Department of Primary Health Care, National Guard Health Affairs, King Saud bin AbdulAziz University for Health Sciences, Jeddah, Saudi Arabia,   Department of Otolaryngology, Head and Neck Surgery, Faculty of Medicine in Rabigh, King Abdulaziz University, Jeddah, Saudi Arabia
Published: August 2021

Objectives

Among medical students, depression, anxiety, and stress (DAS) are key public wellbeing challenges that require epidemiological research. We aimed to evaluate potential sources of these psychological disturbances and assess the contribution of academic and non-academic life stressors in psychological morbidity among medical students.

Methods

This exploratory questionnaire-based survey was conducted in a Saudi Arabian public sector medical college. A total of 231 medical students were enrolled and completed the depression, anxiety, and stress scale-21 (DASS-21) questionnaire.

Results

More than half of the medical students, 129 (55.8%), had depression, 106 (45.9%) students had anxiety, and 87 (37.7%) students had stress. Academic achievement was the largest explanatory factor for depression and stress, whereas bodily appearance constituted the largest explanatory factor of anxiety among the study sample. Academic and non-academic stressors score was significantly associated with depression (adjusted Odds Ratio, aOR = 1.13, 95% CI 1.07–1.19), anxiety (aOR = 1.07, 95% CI 1.03–1.12), and stress (aOR = 1.12, 95% CI 1.08–1.17).

Conclusions

Medical students have a high incidence of negative emotional states. These negative psychological states were explained by academic achievement and bodily appearance. The studied stressors influenced medical students' psychological wellbeing.
France's Role Within NATO
Authors: Belgacem Karim
Published: August 2021

NATO is “brain dead.” With these statements, President Macron shocked most of the member states of the Atlantic alliance. But wouldn't this observation be tinged with realism with the announced withdrawal of the United States from this alliance? The recent attempt at rapprochement between the French President and Vladimir Putin confirms the change of the French paradigm and the will of its president to “move the lines.” Russia's annexation of Crimea and NATO's potential extension to Ukraine have only strained NATO-Russia relations further. This chapter will analyze France's role within NATO since its creation, Franco-Russian relations since the tenure of General de Gaulle in 1958, and the arrival of Emmanuel Macron in 2017. It will put reintegration into perspective of France in the integrated command of NATO, and its two-headed attitude, namely the transatlantic rapprochement but also a realistic observation on the usefulness and the current role of NATO. Will France have an important role to play in the future of NATO?
The West, Russia, and the Baltic Sea Security in the 2020s in the Light of Danish Foreign Policy
Authors: Christensen Carsten Sander
Published: August 2021

The West as well as Moscow challenges the foundations of the European security order. The security order was established shortly after the end of the Cold War in 1990. While growing instability looms over the Baltic Sea region, all the states there should maintain at least low-level regional cooperation with Russia to prevent any further escalation of security tensions. The chapter analyses the West, Russia, and the Baltic Sea Security in the light of Danish foreign policy and the future tasks for NATO in the Baltic Sea area in the 2020s. One key question for the European security community is whether today's confrontation between the EU member states and Russia is the end of its spread to the Baltic Sea region, including Russian districts, and the beginning of a return of geopolitical rivalry in the region. The chapter argues that while each role depicts Denmark as a fringe Nordic country, Nordicness continues to be important, but mostly uncredited, as a source of ideas for Danish foreign policy.
Identification of Bone Density Changes Applying Impedance Spectroscopy with a Piezo-Device Coupled to a Human Tooth
Authors: Ortiz-Jimenez Juliana , Tinoco Hector A. , Cardona Carlos Ivan , Gomez Juan Pablo , Jímenez-Garcia Francy Nelly , Roldan-Restrepo Samuel
Published: August 2021

Bone tissue is a calcium deposit and supporting structure of the human body, it is exposed to several pathologies that modify its mineral content. To determine these changes, different diagnostic procedures are performed with techniques using invasive ionizing radiation, which are limited by the negative effects in the long term on human health. A methodology is explored that could be applicable in the diagnosis of pathologic variations in bone mineral density, using structural monitoring tools. The proposed technique estimates changes in bone conditions by applying impedance spectroscopy with a tooth-borne piezo-device. Bone-tooth samples were prepared to simulate a section of maxillary bone and subsequently treated with chemical agents, simulating pathologic decalcification. The piezo-device is inserted in the slot of an orthodontic bracket, previously bonded to the crown of the tooth, in order to transmit vibration to surrounding bone. The variations in bone micro-architecture were computed by image processing analyzed with samples prepared in transparent resin, allowing the measurement of morphometry before and after the induced changes in mineral content. Using vibrational bone response, impedance measurements allowed to observe the variations in bone mass as the samples were progressively decalcified. In the 5-50kHz spectrum, it was demonstrated the sensitivity of the electro-mechanical impedance during the bone alteration procedure since the electrical resistance signals of the piezo-device consistently changed in the frequency spectrum (5-50kHz). The piezo-device shows to be sensitive to the changes produced by the bone alterations, which were caused by the stiffness variations made in the sample during the decalcifying. These changes were statistically correlated to demonstrate that in a less invasive way, bone alterations could be monitored from the teeth. This result opens the door to search for a new way to diagnose bone density changes in real applications.
Green Synthesis of ZnO Nanoparticles Using Caesalpinia sappan Leaf Extracts and its Antibacterial Activity on Ralstonia solanacearum
Authors: Eugenio Paul Jhon G. , Sarong Marilou M. , Rapanit Keit Sean Amir M. , Galande John Christian Gerard S. , Nilo John Francis , Monserate Juvy J.
Published: August 2021

Abstract. Zinc oxide nanoparticles (ZnO NPs) are known to be one of the multifunctional inorganic nanoparticles with its application in the treatment of bacterial pathogens, especially when synthesized through green nanotechnology. In this study, ZnO NPs were successfully synthesized through co-precipitation method and its antibacterial activity against Ralstonia solanacearum was evaluated. Surface morphology through scanning electron microscope (SEM) exhibited an agglomerated rod-like structures, with a mean particle size of 180.9 nm. Phytochemical screening was performed through various chemical qualitative tests, to which the presence of terpenoids and cardiac glycosides in Caesalpinia sappan leaves was confirmed in the aqueous extract. Five treatments were evaluated against R. Solanacearum in terms of their zone of inhibition. The highest zone of inhibition from the different concentrations was observed from the positive control (Gentamicin) with a mean value of 34.47 mm, followed by 0.57 g/mL ZnO NPs with a mean value of 21.69 mm, and no zone of inhibition on the negative control, 0.28 g/mL, and 0.19 g/mL of synthesized ZnO NPs. Antibacterial activity of ZnO using disc diffusion method resulted in a significant zone of inhibition which proves that synthesized nanoparticles can be used as a potent antibacterial agent against R. solanacearum.
Development of Aldehyde Hyaluronic Acid - N,O-Carboxymethyl Chitosan based Hydrogel for Intraperitoneal Antiadhesion Application
Authors: Widiyanti Prihartini , Priskawati Yolanda Citra Ayu , Wibowo Herry , Ady Jan
Published: August 2021

Intraperitoneal adhesion is a serious case that often occurs with a prevalence of 90-97 % after undergoing gynecological surgery and laparotomy. This study aims are to characterized the hydrogel and identified the optimal composition of Hyaluronic acid (HA) - N, O-carboxymethyl chitosan (NOCC) as an anti-adhesion biomaterial barrier. The synthesis method involved firstly the synthesis of aldehyde derivative of hyaluronic acid (AHA) and also the conversion of chitosan into its derivative, N,O-carboxymethyl chitosan. These two compounds were mixed in various compositions and crosslinked to form N, O-carboxymethyl chitosan (NOCC) /AHA. Fourier-transform infrared spectroscopy has confirmed that the functional groups found -C = O stretching at 1644 cm-1 indicating the hyaluronic acid and carboxymethyl group (-CH2COOH) in 1380 cm-1 which indicate the presence of chitosan. The crosslink is evidenced by the group C = N stretching at a wavenumber of about 1630 cm-1. The best composition of intraperitoneal anti-adhesion is the ratio of hyaluronic acid: chitosan at 30:10 mg/ml. The swelling test is showed a swelling ratio of around 211.8 % in accordance with the standard as intraperitoneal anti-adhesion. Hydrogel has a degradation rate up to 86.87 % on day 10, and this is in accordance with the standard as intraperitoneal anti-adhesion. Cytotoxicity assay showed that hydrogel was nontoxic with a percentage of 92.9 % cell viability. The newly developed hyaluronic acid-carboxymethyl chitosan has characteristics that conform to the criteria of an intraperitoneal anti-adhesion.
The Identification of HSA-MIR-17-5P Existence in the Exosome of Adipose-Derived Stem Cells and Adipocytes
Authors: Murlistyarini Sinta , Aninda Lulus Putri , Afridafaz Ufida Aini , Widyarti Sri , Endharti Agustina Tri , Sardjono Teguh Wahju
Published: August 2021

MicroRNAs (miRNAs) have ability to down-regulate gene expressions. hsa-miR-17-5p, has been confirmed as an oncogene or tumor suppressor. However, the existence on human adipose-derived stem cells (ADSCs) or adipocytes, is still unclear. Many researchers emphasizing the role of hsa-miR-17-5p on cellular senescence, aging and cancer, but not specific on the expression in the exosome of human ADSCs and adipocytes. The primary ADSCs were derived from subcutaneous adipose tissue of pregnant woman during elective cesarean operation, then processed by combining conventional and enzymatic methods. Adipocytes were differentiated by using the StemPro Adipogenesis Differentiation kit® and Oil Red-O staining. Exosomes were isolated using Exosome Purification and RNA Isolation kit® and were characterized by scanning electron microscope. The markers, CD34 and CD44, were identified and analyzed by using FACS analysis. Subsequently, microRNA was extracted and observed for hsa-miR-17-5p expression. This study showed that ADSCs and adipocytes were proved to express CD34+ and CD44+. The hsa-miR-17-5p were also detected in both the exosome of ADSCs and adipocytes. Although the source of the ADSCs was from pregnant woman, the characteristic was similar with the ones from non-pregnant woman. Our study also supports the questionable existence of CD34 in ADSCs. Having confirmed the characteristics, we proved that the exosomes of ADSCs and adipocytes expressed similar hsa-miR-17-5p despite they are from phenotypically different cell types and may have distinct roles. However, further research steps should be done in the future to verify the role of hsa-miR-17-5p towards senescent cell and ADSC differentiation.
A Conceptual Model for Mitigating Security Vulnerabilities in IoT-Based Smart Grid Electric Energy Distribution Systems
Authors: Onawola Hassan Jimoh , Longe Olumide Babatope , Aliyu Garba , Badamasi Bukhari
Published: August 2021

Smart Grid (SG) systems involves large Information Communication Technology (ICT) infrastructure integrated with the power grid system to allow bidirectional flows of information, for effectiveness and to provide economic and sustainable processes that facilitates constant electricity supplies. As a result of open IoT used in smart grid infrastructure, electricity generation and distribution information are getting more vulnerable to online threats. The need to find effective and mitigating measures to the vulnerability and threats in the systems. As broadband network moves from 4G to 5G networks with its attendant advantages, smart grid interoperability will require a well-structured security strategy to avert cyber-attacks and ensure grid security. Cyber-attack issues are critical factors that need to be understood and mitigating techniques developed to ensure the smooth running of smart grid systems. Research has shown that severe vulnerabilities in the implementation of the smart meter pose a threat to grid infrastructure, as such, it is only when these issues are resolved that we can have a sustainable and realistic smart grid technology. This study addressed these concerns by developing a conceptual model for the mitigation of security vulnerabilities in IoT-based smart grid electric energy distribution systems.
Parameter Identification of Lorenz System with Incomplete Information: Case of One Unknown Function
Authors: Shatalov Michael Y. , Surulere Samuel A. , Phadime Lilies M. , Kama Phumezile
Published: August 2021

Inverse problem of the Lorenz system parametric identification is considered in the case of incomplete information about solutions of the system. In the present paper, it is assumed that only two solutions of the system from three are known in different combinations. The problem of the parameter identification of the system is solved by means of elimination of unknown functions from the original system. The obtained system of equations has the same order as the original one, but contains the unknown original parameters in new combinations. Sometimes, the number of new unknown parameters is higher than number of the original unknowns. In this case, the method of the constrained least squares minimization is used in the special formulation, developed by the authors. This novel formulation exploits linearity of the system with respect to the new unknown parameters, by means of which the number of nonlinear equations becomes equal to the number of the constraints between the new parameters. Two methods of the constraint minimization are considered: the classical method of Lagrange’s multipliers and a novel method of the auxiliary parameters. Numerical simulations demonstrate effectiveness of the algorithms.
3D Simulation Modeling for the Electrical Conductivity of Carbon Nanotube Networks in Polymer Nanocomposites
Authors: Luo Yuan Zheng , Wan You Qi , Hong Wei
Published: August 2021

In this paper, we developed a three-dimensional percolation model to investigate the effects of the concentration and morphology of CNTs (carbon nanotubes) on the electrical conductivity of the nanocomposites. In the model, we judged the connections between CNTs by range search algorithm based on KD-Tree structure. At the same time, DIJKSTRA-Melissa algorithm was applied to efficiently find all the conductive paths instead of finding conductive network in traditional methods. From the simulation results, CNTs with higher aspect ratio were easier to form the conductive network. In a certain range of CNT’s concentration, the relationship between the conductivity of the conductive network and the carbon nanotubes was basically consistent with the classical percolation theory. To verify our simulation model, the morphological, electrical properties of Carbon nanotubes (CNTs)/poly(dimethyl siloxane) (PDMS) nanocomposites with different aspect ratio (AR) of MWNTs were systematically studied. In conclusion, these unique advantageous properties could be exploited to suggest potential applications of artificial electronic skin.
MoS2/Graphene Heterostructure Anode for Li-Ion Battery Application: A First-Principles Study
Authors: Shen Yi Yang
Published: August 2021

The development of next generation Li ion battery has attracted many attentions of researchers due to the rapidly increasing demands to portable energy storage devices. General Li metal/alloy anodes are confronted with challenges of dendritic crystal formation and slow charge/discharge rate. Recently, the prosperity of two-dimensional materials opens a new window for the design of battery anode. In the present study, MoS2/graphene heterostructure is investigate for the anode application of Li ion battery using first-principles calculations. The Li binding energy, open-circuit voltage, and electronic band structures are acquired for various Li concentrations. We found the open-circuit voltage decreases from ~2.28 to ~0.4 V for concentration from 0 to 1. Density of states show the electrical conductivity of the intercalated heterostructures can be significantly enhanced. The charge density differences are used to explain the variations of voltage and density of states. Last, ~0.43 eV diffusion energy barrier of Li implies the possible fast charge/discharge rate. Our study indicate MoS2/graphene heterostructure is promising material as Li ion battery anode.
Preparation and some Physical Characterization of Rice Starch - Carboxymethyl Cellulose as Hemostatic Film
Authors: Ruksanti Anucha , Mahapram Benyapa , Thiansem Sakdiphon , Koonawoot Rungsarit , Punyanitya Sittiporn
Published: August 2021

Rice starch (RS) and carboxymethyl cellulose (CMC) are natural polymers that can be widely used for numerous biomedical applications such as hydrogels, capsules, drug delivery system, wound dressing. The purpose of this study was to prepare and investigate the appropriate weight ratio of RS/CMC blend films by solution casting technique. The swelling ratio and solubility were evaluated. The mechanical properties, intermolecular interaction, and morphology were also analyzed by the universal mechanical testing, Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM), respectively. The results indicated that the suitable ratio of RS/CMC blend film was 60/40. The swelling ratio, solubility, tensile strength, and elongation at break were 46.8±0.3 times, 21.63±0.72 %, 30.4±1.5 MPa and 5.76±0.31 %, respectively. Moreover, the physical linkages exhibited mainly between the hydroxyl groups of RS and the carboxyl groups of CMC. In addition, the cross-sectional SEM images of blended films showed the miscibility of RS and CMC. This study suggested that the RS/CMC blended film can be used as a hemostatic film.
Analysis of the Shear Behavior of Fiber-Reinforced Foam Concrete Beams Using Non-Linear Finite Element Method
Authors: Helmi Nizar , Afifuddin Mochammad , Hasan Muttaqin
Published: August 2021

Structural elements such as beams most times experience shear failure suddenly without prior warning and this is different from bending failure which occurs by gradual yielding of tensile reinforcement. A previous experimental research showed that the use of lightweight foam concrete with a fiber mixture has a higher ductility in comparison to the normal concrete. It is also one of the solutions to increase the shear strength capacity of concrete and also has the ability to cause relatively small crack patterns and spread. This research, therefore, aimed to determine the shear behavior of fiber-reinforced foam concrete using a finite element with 3-dimensional modeling in an ATENA V5 software. Moreover, the results obtained were were compared with the findings of the experimental research. The test object used was a beam designed with 15 cm x 30 cm x 220 cm dimensions and the stirrup spacing for the fiber-reinforced foam concrete (BBSN-20) was 20 cm while the normal beam (BN-25) had 25 cm. The numerical analysis was observed to have shown closer values to the experimental results with the difference in the ultimate load on the BBSN-20 and BN-25 recorded to be only 7.73% and 12.6% while the ultimate deflection was 6.92% and 32.45% respectively. Meanwhile, the beam destruction patterns in both the numerical and experimental models were similar but the numerical analysis showed the two beams modeled did not experience shear failure as planned.
Effects of Nozzle and Roll on Surface Condition of Al-1%Si Strip Cast Using Vertical type High Speed Twin Roll Caster
Authors: Haga Toshio , Okada Tomoya , Nishida Shinichi , Watari Hisaki
Published: August 2021

When a strip of Al-Si alloy with an Si content of 1% was cast using a vertical-type high-speed twin-roll caster, cracks form in its surface. The effects of the pouring method, the shape and position of the nozzle, and the roll surface texture on surface crack formation were evaluated with a roll caster. The rolls were made of a copper alloy, and the roll speed was 30 m/min. The as-cast strips were bent to investigate the degree of crack formation, and the outer surface of the strips was observed without magnification and with a stereomicroscope to determine the influence of the pouring method, the shape and position of the nozzle, and the roll surface. A roll machined to form V-shaped grooves 0.4 mm deep on the surface of the strips was most useful for reducing surface cracking. Changing the shape of the nozzle tip was second-most effective. There was a clear correlation between the roll surface condition and surface cracking in the Al-Si strip.
Casting of Thin Aluminum Alloy Rod Using Twin Wheel Caster Equipped with Rotating Side Dam Plates
Authors: Haga Toshio , Okuda Naotsugu , Watari Hisaki , Nishida Shinichi
Published: August 2021

A thin aluminum rod (width: 5 mm) was cast using a twin-wheel caster equipped with rotating side-dam plates. The upper and lower casting wheels were made of copper. The width of the flat upper and lower casting wheels was 5 mm. The rotating side-dam plate was made of mild steel. Paper 0.5 mm thick was pasted onto the plate. Boron nitride was sprayed onto the paper as an insulator and lubricant. A 6061 aluminum alloy thin rod could be cast continuously at casting speeds of 4 and 5 m/min. Molten metal was poured onto the lower wheel from a launder and conveyed into a square gap made by the lower wheel, upper wheel, and side-dam plates. The cross section of the cast rod was rectangular. The cross-sectional area of the rectangular rod was 12 to 15 mm2.
Gravimetric and Data Analysis of the Protection Performance of Plant Extracts on Plain Carbon Steel in Dilute H2SO4 Solution
Authors: Loto Roland Tolulope , Loto Cleophas Akinloto , Okeniyi Joshua , Agobe Enifo Igbunu , Opeoluwa Adenmolu
Published: August 2021

Analysis of the protection performance of kolanut leaves (KL), kolanut fruits (KF), tobacco leaves (TL) and bitter leaves (BL) extracts at 30%, 60% and 80% concentration on plain carbon steel in 0.5 M H2SO4solution was done by gravimetric measurement and statistical evaluation. Data output showed KF and TL extracts performed effectively at all concentrations studied with protection performance output generally above 80%. KL and BL extracts performed poorly at the lowest concentration while at higher concentrations optimal protection performance outputs are 74.41% and 83.53%. The protection performance outputs of KL, KF and TL extracts varied significantly with observation time due to thermodynamic instability and unstable inhibition behavior. BF extract exhibited stable inhibition behavior due to general stability of its protection performance outputs with respect to observation time. BF and KL exhibited the highest and lowest standard deviation due to the degree of variation of their protection performance outputs from mean value. Data showed 9.5%, 76.2%, 76.2% and 71.4% of the protection performance outputs of KL, KF, TL and BL extracts are above 80% inhibition performance at margin of error of 12.6%, 18.2%, 18.2% and 19.3%. Data from analysis of variance shows that observation time exerted more influence than extract concentration on the protection performance outputs of KL, KF and TL extracts with statistical relevance values of 91.24%, 91.93% and 93.61%. BL extract concentration exhibited significant influence on the protection performance outputs of BL compared to observation time with statistical relevance values of 81.43%.