bluuebunny/crossref_metadata_2025 huggingface dataset:
A new code for low-resolution spectral identification of white dwarf binary candidates
Authors: Liu Genghao , Tang Baitian , Ren Liangliang , Li Chengyuan , Cheng Sihao , Zong Weikai , Fu Jianning , Ma Bo , Xu Cheng , Hu Yiming
Published: August 2024

Context. Close white dwarf binaries (CWDBs) are considered to be progenitors of several exotic astronomical phenomena (e.g., type Ia supernovae, cataclysmic variables). These violent events are broadly used in studies of general relativity and cosmology. However, obtaining precise stellar parameter measurements for both components of CWDBs is a challenging task given their low luminosities, swift time variation, and complex orbits. High-resolution spectra (R > 20 000) are preferred but expensive, resulting in a sample size that is insufficient for robust population study. Recently, studies have shown that the more accessible low-resolution (R ~ 2000) spectra (LRS) may also provide enough information for spectral decomposition. To release the full potential of the less expensive low-resolution spectroscopic surveys, and thus greatly expand the CWDB sample size, it is necessary to develop a robust pipeline for spectra decomposition and analysis.

Aims. We aim to develop a spectroscopic fitting program for white dwarf binary systems based on photometry, LRS, and stellar evolutionary models. The outputs include stellar parameters of both companions in the binary including effective temperature, surface gravity, mass, radius, and metallicity in the case of MS stars.

Methods. We used an artificial neural network (ANN) to build spectrum generators for DA/DB white dwarfs and main-sequence stars. Characteristic spectral lines were used to decompose the spectrum of each component. The best-fit stellar parameters were obtained by finding the least χ2 solution to these feature lines and the continuum simultaneously. Compared to previous studies, our code is innovative in the following aspects: (1) implementing a sophisticated binary decomposition technique in LRS for the first time; (2) using flux-calibrated spectra instead of photometry plus spectral lines, in which the latter requires multi-epoch observations; (3) applying an ANN in binary decomposition, which significantly improves the efficiency and accuracy of generated spectra.

Results. We demonstrate the reliability of our code with two well-studied CWDBs, WD 1534+503 and PG 1224+309. We also estimate the stellar parameters of 14 newly identified CWDB candidates, most of which are fitted with double component models for the first time. Our estimates agree with previous results for the common stars and follow the statistical distribution in the literature.

Conclusions. We provide a robust program for fitting binary spectra of various resolutions. Its application to a large volume of white dwarf binary candidates will offer important statistic samples to stellar evolution studies and future gravitational wave monitoring.
Early Planet Formation in Embedded Disks (eDisk)
Authors: Santamaría-Miranda Alejandro , de Gregorio-Monsalvo Itziar , Ohashi Nagayoshi , Tobin John J. , Sai Jinshi , Jørgensen Jes K. , Aso Yusuke , Daniel Lin Zhe-Yu , Flores Christian , Kido Miyu , Koch Patrick M. , Kwon Woojin , Lee Chang Won , Li Zhi-Yun , Looney Leslie W. , Plunkett Adele L. , Takakuwa Shigehisa , R van’t Hoff Merel L. , Williams Jonathan P. , Yen Hsi-Wei
Published: August 2024

We present the results of the observations made within the ALMA Large Program called Early Planet Formation in Embedded disks of the Class 0 protostar GSS30 IRS3. Our observations included the 1.3 mm continuum with a resolution of 0″.05 (7.8 au) and several molecular species, including 12CO, 13CO, C18O, H2CO, and c-C3H2. The dust continuum analysis unveiled a disk-shaped structure with a major axis of ~200 au. We observed an asymmetry in the minor axis of the continuum emission suggesting that the emission is optically thick and the disk is flared. On the other hand, we identified two prominent bumps along the major axis located at distances of 26 and 50 au from the central protostar. The origin of the bumps remains uncertain and might be an embedded substructure within the disk or the temperature distribution and not the surface density because the continuum emission is optically thick. The 12CO emission reveals a molecular outflow consisting of three distinct components: a collimated component, an intermediate-velocity component exhibiting an hourglass shape, and a wider angle low-velocity component. We associate these components with the coexistence of a jet and a disk wind. The C18O emission traces both a circumstellar disk in Keplerian rotation and the infall of the rotating envelope. We measured a stellar dynamical mass of 0.35 ±0.09 M⊙.
Energy flexibility using thermal mass for Swedish single-family houses
Authors: Chen Huijuan , Ruud Svein , Markusson Caroline
Published: August 2024

This paper characterised the potential of energy flexibility in relation to building envelop properties, heat emitters and ventilation for the Swedish context. Simulation results indicated that the potential was higher for newer houses with floor heating and lower for older houses with radiators in winter. Older houses with different levels of insulation showed a similar ability of conserving heat due to different extents of heat losses from ventilation. A house with balanced ventilation tended to be over-ventilated especially if the house was not airtight. The flexibility was decreased with increasing outdoor temperatures, and it was higher in winter and lower in spring/autumn.
Simulation-based assessment of natural and mechanical ventilation solutions for renovated apartment buildings in Denmark
Authors: Egholm Nielsen Andreas , Hvidtfeldt Jakobsen Oliver , Michael Smith Kevin , Kolarik Jakub
Published: August 2024

Many European buildings require renovation, often involving window replacements and improved airtightness, leading to increased mold risk and indoor air quality (IAQ) issues. Solutions include adjustable air inlets with mechanical exhaust or balanced heat recovery ventilation. Using building performance simulations, we studied control strategies for renovated apartment building with natural or mechanical ventilation. CO2 - controlled air inlets proved most effective for IAQ and energy reduction. In different apartment positions, air inlet performance varied based on available stack effect. Mechanical exhaust cases were less affected by airtightness changes. Altogether, the mechanical ventilation was more robust, but all strategies were sensitive to closed doors.
Transient zonal model for predicting indoor airflows in naturally ventilated buildings: A case study of hospital patient rooms
Authors: Lastovets Natalia , Luoto Anni , Elsayed Mohamed , Sormunen Piia
Published: August 2024

Proper ventilation dilutes viral concentrations and reduces infection risk. Advanced simulation methods are needed to understand indoor airflow dynamics in naturally ventilated spaces, like hospital patient rooms. Predicting airflow distribution is complex due to factors such as variable opening sizes, changing weather conditions, and exhaust shaft locations. Simulation methods, such as Computational Fluid Dynamics (CFD), building energy simulation, and analytical mathematical models are used to address these challenges. Zonal models, in particular, bridge the gap between the simplicity of standard perfectly mixed room air assumptions and the computational intensity of CFD simulations. This research presents a case study of patient rooms in a hospital located in Romania. The study focuses on validating a coarse grid zonal model implemented in the building simulation tool IDA ICE for predicting indoor airflow in patient rooms with natural ventilation. The model is validated against field measurements of indoor air parameters in the patient room. This study demonstrates the capability of a one-dimensional transient zonal model integrated into building simulation software to predict main indoor air distribution patterns. This model requires minimal prior knowledge of airflow characteristics, making it a versatile tool for predicting indoor air quality in naturally ventilated hospital buildings. The method can identify risky areas for infection control and optimise ventilation in healthcare facilities.
Case Studies On The Application Of Building Simulation Software SIM-VICUS Within The Real Planning Process
Authors: Weiß Dirk , Tribulowski Katja , Hirth Stephan , Hirsch Hauke
Published: August 2024

Renewable energy concepts for buildings and districts are increasingly demanded in order to meet both international climate goals and national legal requirements. In this context, we developed comprehensive concepts for different buildings and districts in practice, making extensive use of detailed building simulations for a reliable prediction of energy demands. Main goal was to achieve a reasonable compromise between independency from fossil price fluctuations and economic efficiency. In this paper, we present the according planning process and the concepts, which are currently being realised or in further planning phases.
Validation of the Energy Demand Load Profile Estimator “PROFet” for Trondheim Non-residential Buildings
Authors: Mohammadabadi Abolfazl , Sartori Igor , Georges Laurent
Published: August 2024

Accurate long-term forecasts of aggregate energy load profiles are crucial for effective energy system planning at regional and national scales. This study aims to validate PROFet, a flexible load profile modeling tool. PROFet forecasts weather-dependent heating and electrical load profiles at an hourly resolution for both residential and non-residential buildings connected to district heating systems. Given that the tool’s accuracy for residential buildings has been demonstrated in previous studies, further validation is needed for non-residential buildings. To achieve this, our study evaluates PROFet’s extrapolation performance using an out-of-sample test dataset from Trondheim municipality. The results show that PROFet accurately forecasts the hourly heating load during the space-heating season but is less accurate during periods when domestic hot water needs dominate. The tool exhibits nearly identical performance across the three cases, except for efficient kindergartens, where the estimation accuracy is lower.
β and γ vibrations in the IBM
Authors: Bijker Roelof , Mas Ruiz Javier
Published: August 2024

The properties of β- and γ-bands are analyzed in the framework of the IBM. It is shown that the general features of the observed excitation energies and the transition probabilities to the ground state band can be explained simply in terms of the intrinsic states of the IBM.
On-line installation of the Superallowed Transition Beta-Neutrino Decay Ion Coincidence Trap
Authors: Brodeur M. , Bardayan D.W. , Bruce O. , Bualuan R. , Burdette D.P. , Clark J.A. , Gallant A.T. , Gan D. , Guillet D. , Houff A.M. , Kolata J.J. , Liu B. , O’Malley P.D. , Porter W.S. , Quick C. , Rivero F. , Savard G. , von Seeger W.W. , Valverde A.A. , Zite R.
Published: August 2024

The Cabibbo-Kobayashi-Maskawa quark mixing matrix currently does not satisfy unitarity at the 2σ-level. This could be the result of an inaccurate value of one or both of its largest matrix elements Vus and Vud. In the case of Vud, the most precise measurement is obtained from the f t-value measurements of superallowed beta-transitions between 0+ states. The accuracy of this determination can, in turn, be tested by extracting Vud in other transitions including superallowed transitions between mirror nuclei. The Superallowed Transition Beta-Neutrino Decay Ion Coincidence Trap (St. Benedict) is currently under construction at the Nuclear Science Laboratory of the University of Notre Dame to perform such a determination, with the goal of shedding more light on this tension with unitarity. St. Benedict will take a radioactive ion beam produced by TwinSol, thermalize it in a large volume gas catcher, then transport it in two separate differentially-pumped volumes using a radio-frequency (RF) carpet and a radio-frequency quadrupole (RFQ) ion guide before injecting it in an RFQ trap to create cool ion bunches for injection in the measurement Paul trap. In this paper, we detail the installation of the beam preparation components of St. Benedict, and present the results of the first RIBs successfully stopped and extracted from its gas catcher.
Using indirect methods to explore low-energy fusion cross sections in nuclear astrophysics
Authors: La Cognata Marco
Published: August 2024

Nuclear reactions within stellar environments typically manifest at energies well below 1 MeV. As a consequence, the Coulomb barrier strongly suppresses the cross section, diminishing it to values as minute as a few nanobarns for charged particles. This challenge in obtaining precise input data for astrophysics has prompted the utilization of indirect methodologies. Specifically, approaches such as ANC and THM have been employed to ascertain cross sections for reactions involving photons and charged particles in the exit channel, respectively, obviating the necessity for extrapolation. The discourse explores recent findings arising from the application of these methodologies. For example, the measurement of6Li(3He,d)7Be is employed to infer the ANC’s of the3He+4He→7Be andp+6Li→7Be channels, along with their corresponding radiative-capture cross sections. Furthermore, the THM measurement of the27Al(p,α)24Mg cross section via the2H(27Al,α24Mg)nreaction is emphasized. In both instances, the cross section at astrophysical energies has been ascertained with unparalleled precision.
Measurement of muon flux variations with scintillators in Mexico City and their correlation to solar activity
Authors: Montiel Diego Martínez , Serkin Leonid , Paic Guy , Patiño Salazar Miguel Enrique , Guerra Pulido Jaime Octavio , Vázquez Villamar Carlos Rafael
Published: August 2024

In this work we report the variations of the atmospheric muons flux in Mexico City. The measurements were performed from September to December 2023 at the Institute of Nuclear Sciences of UNAM, located at coordinates 19.32°N 99.18°W with an altitude of 2274 meters above sea level and a cutoﬀ rigidity of 8.24 GV. The experimental setup consists of a pair of scintillators, with dimensions of 50cm x 1m. To compensate for fluctuations in air pressure, we calculate the barometric coeﬃcient using data, which is determined to be -0.21%/mb. The observed muon flux corresponds to 98.3 ± 2.6 m−2 s−1 sr−1 and is consistent with other measurements at the same location. We have identified three variations in the pressure-corrected muon flux that exhibit a pattern similar to those observed by a neutron cosmic ray detector at UNAM. Through an extensive analysis of the publicly available geomagnetic data, we have correlated these variations with a phenomenon known as a Forbush decrease.
Schlaf, mein Kind, schlaf (f)ein …
Authors: Grenzer Stefan
Published: August 2024

Schlaf und Schlafprobleme sind in vielen Familien Thema: kindliches Schlafverhalten, Einschlafzeiten, Umgang mit Wachphasen oder der Mittagsschlaf – Unsicherheiten sind groß und Anlass für besorgte Fragen. Eltern, aber auch Pflegende müssen die Bedürfnisse eines Kindes erkennen und adäquat darauf reagieren können: Schlaf ist gerade für Kinder essenziell und eine wichtige Entwicklungsaufgabe. Um für guten Schlaf zu sorgen, Heranwachsende und Eltern dahingehend zu beraten und die Genesung im Krankenhaus zu fördern, sind die Kenntnis und Beachtung des Schlafs, seiner physiologischen Abläufe und seiner Entwicklung unabdingbar.
Pflegerische Interventionen in der Nachsorge brandverletzter Kinder und Jugendlicher
Authors: Malkots Alina , Bachmann Sandra , Riede Jens
Published: August 2024

Der zweite Beitrag zum Thema über die Versorgung von brandverletzten Kindern und Jugendlichen thematisiert die aktuelle Evidenz und die Empfehlungen zur pflegerischen Versorgung in der Nachsorge. Dem Beitrag liegt eine Bachelorarbeit zugrunde, die sowohl die Akutversorgung als auch die Nachsorge untersucht. Die pflegerische Versorgung in der Akutphase brandverletzter Kinder und Jugendlicher wurde bereits in der JuKiP 03/2024 vorgestellt.
Das schwere Thoraxtrauma: Indikationen und Kontraindikationen für operative und nicht operative Versorgungsstrategien
Authors: Spering Christopher , Lehmann Wolfgang
Published: August 2024

Das schwere Thoraxtrauma kann einerseits als penetrierende oder stumpfe Monoverletzung oder im Rahmen einer Polytraumatisierung auftreten. Bei der Hälfte der im TraumaRegister DGU dokumentierten Schwerverletzten ist ein schweres Thoraxtrauma, definiert nach Abbreviated Injury Scale (AIS) mit ≥ 3, diagnostiziert worden. Im eigenen Kollektiv betrug der Anteil 60%. Die Notfallthorakotomie im Schockraum oder innerhalb der 1. Stunde nach Aufnahme ist in Deutschland mit 0,9% der schweren Thoraxverletzungen eine äußerst seltene Intervention. Das differenzierte Management von komplexen Polytraumata und umfangreichen pathophysiologischen Reaktionen auf die Traumatisierung haben ebenso wie das Wissen über die Entstehung von Sekundärschaden dazu geführt, dass durch minimalinvasive Verfahren wie videoassistierte Thorakoskopien (VATS) oder das Einlegen einer Thoraxdrainage der Großteil der schweren Thoraxverletzungen erfolgreich therapiert werden kann. Dabei sind penetrierende
Verletzungen des Thorax mit < 4% eine Seltenheit. Mit steigender Tendenz weisen unter den stumpfen Thoraxverletzungen > 6% eine instabile Thoraxwand auf, die einer operativen Rekonstruktion bedarf. Die demografische Entwicklung in Deutschland führt dazu, dass zunehmend auch Niedrigenergietraumata zu höhergradigen Thoraxwandverletzungen mit penetrierenden Rippenfrakturen in Pleura, Lunge, Peri- bzw. Myokard und Zwerchfell führen. Eine Thoraxwandinstabilität mit hochgradiger Einschränkung der Atemmechanik kann zu fulminanten Pneumonien bis hin zum ARDS (Acute Respiratory Distress Syndrome) führen. In der vergangenen Dekade hat vor diesem Hintergrund die operative Thoraxwandrekonstruktion stark an Bedeutung gewonnen. Auf der Grundlage der überzeugenden Evidenz ist die klinische Beurteilung des Umfangs und der Schwere des Traumas und der Grad der atemmechanischen Einschränkung die Basis für eine strukturierte Entscheidung über eine nicht operative oder
operativ-rekonstruktive Strategie sowie den OP-Zeitpunkt, die OP-Art und den OP-Umfang. Durch die frühzeitige OP innerhalb von 72 h können Morbidität (Pneumonierate, Intensivliegedauer und Beatmungsdauer) sowie Letalität verringert werden. In dem folgenden Artikel werden evidenzbasierte Algorithmen zur operativen und nicht operativen Versorgungsstrategie von schweren Thoraxverletzungen diskutiert. Dazu wurden in einer selektiven Literaturrecherche die wegweisenden Veröffentlichungen zu Indikationsstellung, Versorgungsstrategie und Therapieempfehlungen der schweren Thoraxverletzung sowie Thoraxwandrekonstruktion eingeschlossen.
Schwerstverletztenversorgung in kriegerischen Auseinandersetzungen
Authors: Franke Axel , Sahm Joachim , Bieler Dan , Achatz Gerhard
Published: August 2024

Durch den aktuellen Krieg in der Ukraine steht die Behandlung von Kriegsverletzungen in der öffentlichen Diskussion. Die hierzulande stattfindende Weiterversorgung von Verletzten aus der Ukraine nach Verteilung im Kleeblatt in die TraumaNetzwerke DGU steht nicht zuletzt durch die Forderung des Bundesverteidigungsministeriums und des Bundesgesundheitsministeriums, die Bundeswehr und das deutsche Gesundheitssystem gegenüber potenziellen Belastungen aus kriegerischen Auseinandersetzungen resilienter (kriegstüchtig) zu machen, im Fokus.Um ein Verständnis für die erwartbaren Behandlungsergebnisse, die Vorgehensweisen im Einsatz, aber auch die Unwägbarkeiten der Schwerstverletztenversorgung unter Einsatzbedingungen zu etablieren, ist es das Ziel des vorliegenden Artikels, die Besonderheiten der Schwerstverletztenversorgung in kriegerischen Auseinandersetzungen darzustellen.Durch eine Literaturrecherche werden die Herausforderungen und typischen Verletzungsmuster am
Beispiel des Einsatzes der Bundeswehr in Afghanistan und des aktuellen Krieges in der Ukraine dargestellt. Es wird ein Überblick über die Faktoren gegeben, die abweichend von der gut etablierten und standardisierten, zivilen Polytraumaversorgung in Deutschland die Vorgehensweisen und die Ergebnisqualität unter Einsatzbedingungen beeinflussen können.Die Schwerstverletztenversorgung erfolgt auch im Einsatz der Bundeswehr oder wie aktuell konzipiert für den Einsatz der NATO unter standardisierten Bedingungen, die sich an der algorithmenbasierten Versorgung des ATLS mit Fokus auf Blutungskontrolle orientiert. Dies ist materiell und personell gut etabliert, vorbereitet und geschult.Einzelne Ländergegebenheiten bzw. Einsatzerfordernisse können aber dazu führen, dass die erste ärztliche notfallmedizinische Versorgung abweichend vom zivilen System in Deutschland erst zeitverzögert und nach längerem Transport erfolgen kann. Ziel ist es hierbei immer, für die eingesetzten
Soldaten eine im Ergebnis gleichwertige Versorgung abzubilden, wie sie hier in Deutschland jedem Unfallopfer, unabhängig von Zeit und Ort des Unfalles, potenziell zur Verfügung steht.
Nicht alles ist Rheuma: Systemische Inflammation und autoimmune
Phänomene
Authors: Kittel Christoph , Unger Leonore
Published: August 2024

In unserer täglichen Praxis begegnen uns immer wieder Patienten mit fulminanten
Entzündungsreaktionen mit organbedrohendem Verlauf. Wir stellen zwei junge
Frauen mit einer ausgeprägten systemischen Entzündung und verschiedenen
Autoimmunphänomenen vor. In beiden Fällen lag letztlich ein papilläres
Schilddrüsenkarzinom vor. Die erste Patientin wurde mit dem Verdacht einer
ANCA-assoziierten Vaskulitis in erheblich beeinträchtigtem Allgemeinzustand
vorgestellt. Klinisch bestanden Kopf-, Nacken- und Thoraxschmerzen neben einem
deutlich erhöhten CRP und einem undifferenzierten niedrig-titrigen ANCA. Die
Biopsie eines echoarmen Schilddrüsenknotens erbrachte keinen Anhalt für
Malignität. Trotz eines Therapieversuches mit Prednisolon kam es nach kurzer
Zeit zur Wiedervorstellung nun mit zusätzlich Übelkeit, Erbrechen und einer sehr
schmerzhaften, lividen Verfärbung der Finger der linken Hand bei weiter deutlich
erhöhtem CRP. Ein PET-CT zeigte neben Lymphadenopathien eine deutliche Tracer-
Anreicherung im rechten Schilddrüsenlappen. In der nachfolgenden Thyreoidektomie
ließ sich nun das papilläre Schilddrüsenkarzinom beweisen. Die
Autoimmunphänomene sind im Rahmen einer Paraneoplasie zu interpretieren. Im
zweiten Fall handelt es sich um eine Patientin mit einem bekannten Systemischen
Lupus erythematodes, die durch ein Erysipel, welches unter der Immunsuppression
aufgetreten ist, in einen schweren Schub des Lupus gekommen ist. Im Rahmen der
ausführlichen Umfelddiagnostik konnte ein kleines papilläres
Schilddrüsenkarzinom diagnostiziert werden und frühzeitig kurativ operiert
werden.
Chimäre Antigenrezeptor-T-Zellen – Die Evolution zellulärer
Immuntherapie von malignen zu nicht-malignen Erkrankungen
Authors: Luu Maik , Hudecek Michael , Schmalzing Marc
Published: August 2024

Immunonkologische Therapien wie Immuncheckpoint-Inhibitoren (ICIs) und
bispezifische Antikörper haben die Behandlung von soliden und hämatologischen
Tumorentitäten mit einem neuen Arsenal an Möglichkeiten ausgestattet. Dabei
spielen T-Zellen eine zentrale Rolle bei der Bekämpfung entarteter Zellen.
Moderne Gen-Transfer- und -Engineering-Methoden haben im letzten Jahrzehnt die
Kombination von synthetischer Biologie und adoptiver, zellulärer Immuntherapie
ermöglicht und somit die Ausstattung von Patienten-T-Zellen mit chimären
Antigenrezeptoren (CAR). Diese vereinen die Antigen-bindenden Eigenschaften von
Antikörpern mit den Signal-gebenden Domänen des T-Zell-Rezeptors und erlauben
den so entstehenden CAR-T-Zellen die Zerstörung von Tumorzellen in
Antigen-spezifischer Art und Weise. Diese „living drugs“ haben insbesondere die
Behandlung B-Zell-vermittelter, hämatologischer Erkrankungen revolutioniert und
zeigen neben hohen Ansprech- ebenso langjährige Remissionsraten. Die Möglichkeit
CAR gegen neue Zielantigene zu generieren und auch die Eigenschaften von
T-Zellen über Genom-Editierung zu steuern führt das Feld nicht nur immer weiter
in den Bereich der soliden Tumore, sondern gleichsam in das Feld nicht-maligner
Erkrankungen. Insbesondere die tiefe B-Zell-Depletion über CD19-CAR-T-Zellen hat
bei ersten Patienten mit Systemischem Lupus erythematosus (SLE) und anderen
Kollagenosen zu beachtlichen Erfolgen geführt. Dabei beschränkt sich die bisher
publizierte Erfahrung auf kleine Fallserien und Fallberichte. Auf Basis dieser
Daten ist ebenso der Einsatz von CAR-T-Zellen in anderen B-Zell-vermittelten
Autoimmunitäten denkbar und wird die Rheumatologie in Zukunft gewiss
beschäftigen. Mehrere Phase 1- und 2-Studien zu CAR-T-Zell-Therapien bei
Autoimmunerkrankung werden aktuell entwickelt oder schon initiiert. Der
vorliegende Artikel soll die Grundzüge der CAR-T-Zell-Technologie erläutern
sowie ihre Perspektiven für die Verwendung im Bereich nicht-maligner
Erkrankungen beleuchten.
Concise Asymmetric Synthesis of Deepoxyalchornoic Acid and (12R,13R)-Isoleukotoxin Diol
Authors: Fernandes Rodney A. , Gorve Dnyaneshwar A. , Papnai Himanshu
Published: August 2024

The first asymmetric synthesis and structural confirmation of deepoxyalchornoic acid have been accomplished from commercially available starting materials. Asymmetric dihydroxylation and Wittig olefination has been strategically executed to achieve a concise synthesis of deepoxyalchornoic acid and (12R,13R)-isoleukotoxin diol from a common intermediate chiral γ-lactone.
Impacts on Rural Community Development and Governance by Different Land Ownership: A Comparative Study Based on Two Villages in China
Authors: Yang Jieying , Yu Li , Zhang Jingxiang
Published: August 2024

The capability of rural community governance is significantly impacted by the different types of land ownership when capital investment in rural tourism to achieve rural revitalisation. The outcomes of which profoundly affect sustainable rural development. This study, by utilising a theoretical framework using double movement theory, aims to assess the impacts on rural community governance by two different land ownership models, the Enterprise-based Model (EBM) and the Community-based Model (CBM), in the process of capital flow to the countryside (CFC). Case studies of the two villages were adopted to examine and explore the logic of interaction between stakeholders and reveal the internal mechanism of rural community governance. The results of this research indicate that the CBM has considerable advantages over the EBM. In the CBM, the village collective retains land ownership without fully marketising, which allows villagers to maintain their bargaining power with investors whilst increasing their local awareness. In the EBM, however, the local government promotes the conversion of land ownership. The villagers benefit more from one-time acquisition but lose sustainable benefits created by local development. Stakeholders call for the need to create a development model beyond the market economy by maintaining China's rural land system in the process of CFC. In this regard, this paper provides an original contribution.
A multi-mode stretching apparatus for in situ synchrotron x-ray scattering of polymer materials
Authors: Yang Bo , Yuan Zhen , Dong Xia , Liu Guoming , Wang Dujin
Published: August 2024

A compact and versatile tensile apparatus for polymer materials is designed and fabricated. Three distinct stretching modes are developed: constant speed, cyclic, and sinusoidal, with adjustable speeds ranging from 0.001 to 120 mm/s. To capture the true strain of the central region, a high-speed camera has been integrated into the apparatus. The temperature of the sample chamber is controlled by flowing air, enabling a homogeneous temperature in the range of RT ∼200 °C. The apparatus is particularly suitable for a synchrotron beamline. The structural evolution of natural rubber during sinusoidal stretching is investigated by in situ wide-angle x-ray scattering. Scattering patterns, force, clamp position, and sample images are saved simultaneously during stretching. Notably, the results reveal a sinusoidal variation in the crystallinity of crosslinked natural rubber when a sinusoidal strain was applied to the sample. The integration of advanced measurement techniques and controlled experimental conditions ensures the acquisition of reliable and accurate data, providing valuable insights into the structural evolution of materials under dynamic deformation conditions.
Enhancing growth rate in homoepitaxial growth of β-Ga2O3 with flat surface via hydrochloric acid addition in mist CVD
Authors: Ueda Ryo , Nishinaka Hiroyuki , Miyake Hiroki , Yoshimoto Masahiro
Published: August 2024

Gallium oxide (Ga2O3) is a wide-bandgap oxide semiconductor, with a bandgap of ∼4.9 eV, making it a promising material for power device applications. This study focuses on the effect of hydrochloric acid addition on the growth rate in homoepitaxial growth of β-Ga2O3 using a mist chemical vapor deposition method. For homoepitaxial growth on a (001) β-Ga2O3 substrate, we introduced different concentrations of HCl into the source solution to assess its impact on the growth rate, crystal structures, and surface morphologies of the films. At a growth temperature of 900 °C, HCl addition linearly increased film thickness, enhancing the growth rate by 4.8 times with 9.09 vol. % HCl. No peaks associated with other phases were exhibited by each sample, indicating pure homoepitaxial growth. When comparing samples with similar film thicknesses, the root-mean-square (rms) roughness was enhanced by 1/7 with an increase in the HCl concentration. However, at 800 °C, an increasing solution concentration caused pronounced step bunching and elevated rms roughness, in contrast with the minimal effect observed at 900 °C. In experiments with hydrochloric acid addition at 900 °C, we observed a striped morphology, which maintained consistent rms roughness despite higher temperature.
Layer-by-layer unsupervised clustering of statistically relevant fluctuations in noisy time-series data of complex dynamical systems
Authors: Becchi Matteo , Fantolino Federico , Pavan Giovanni M.
Published: August 2024

Complex systems are typically characterized by intricate internal dynamics that are often hard to elucidate. Ideally, this requires methods that allow to detect and classify in an unsupervised way the microscopic dynamical events occurring in the system. However, decoupling statistically relevant fluctuations from the internal noise remains most often nontrivial. Here, we describe “Onion Clustering”: a simple, iterative unsupervised clustering method that efficiently detects and classifies statistically relevant fluctuations in noisy time-series data. We demonstrate its efficiency by analyzing simulation and experimental trajectories of various systems with complex internal dynamics, ranging from the atomic- to the microscopic-scale, in- and out-of-equilibrium. The method is based on an iterative detect-classify-archive approach. In a similar way as peeling the external (evident) layer of an onion reveals the internal hidden ones, the method performs a first detection/classification of the most populated dynamical environment in the system and of its characteristic noise. The signal of such dynamical cluster is then removed from the time-series data and the remaining part, cleared-out from its noise, is analyzed again. At every iteration, the detection of hidden dynamical subdomains is facilitated by an increasing (and adaptive) relevance-to-noise ratio. The process iterates until no new dynamical domains can be uncovered, revealing, as an output, the number of clusters that can be effectively distinguished/classified in a statistically robust way as a function of the time-resolution of the analysis.Onion Clusteringis general and benefits from clear-cut physical interpretability. We expect that it will help analyzing a variety of complex dynamical systems and time-series data.
In-person learning during the pandemic: Student take-up and school-level effects of remote and hybrid instruction on student outcomes
Authors: Ross Stephen L. , Jiang Shangyue , Young Michael F. , Meyer Joanna L. , Strambler Michael J.
Published: August 2024

While studies have examined the effects of schools offering in-person learning during the pandemic, this study provides analysis of student enrollment decisions (remote versus in-person) in response to schools providing in-person learning opportunities. In Connecticut during the 2020–21 school year, we find that student take-up of in-person learning opportunities was low with students on average enrolled in-person for only half of the days offered, and take-up was even lower in schools with larger shares of disadvantaged students. The provision of in-person learning opportunities has been previously shown to mitigate pandemic learning losses. By exploiting data on actual enrollment, we show that the protective benefits of in-person learning are twice as large as previously estimated once we account for the low rates of student take-up. Finally, we provide evidence suggesting that a key mechanism behind the benefits of in-person learning is alleviating the burden faced by schools and teachers in delivering remote education. First, we show that the benefits to individual students of their in-person learning are substantially smaller than the overall benefits a student receives from their school average level of in-person enrollment. Second, we show that a combination of remote and in-person learning (hybrid) with a full-time on-line presence of students when at home was worse than hybrid learning with students never or only partially online. This second finding is consistent with qualitative evidence showing that teachers found hybrid learning especially challenging when having to manage both in-person and remote students for the entire class period.
A space-borne ultra-stable laser system with an excellent long-term frequency stability for gravitational wave detection
Authors: Chang Jialu , Wu Qiyue , Wang Zhiyuan , Zhang Jingxuan , Wei Qiang , Yuan Wenhao , Zhu Deyuan , Zhang Jiarui , Li Xuying , Wu Xinpeng , Lu Zehuang , Zhang Jie
Published: August 2024

Ultra-stable lasers are pivotal in various scientific applications, notably in space gravitational wave detection projects. We develop a space-borne ultra-stable laser system based on a home-made non-planar ring oscillator (NPRO) laser and an ultra-stable cavity laser stabilization system. The ultra-stable cavity is a vertically mounted 8 cm long cavity, with tunable zero-crossing temperature and low vibrational sensitivity. To make a cavity with any standard grade ultra-low expansion glass (ULE) material, and tune the zero-crossing temperature to the satellite platform temperature, we design three ultra-stable cavities with different configurations to unambiguously explore their thermal properties. The measurement results meet the design goals well, and the zero-crossing temperature of the cavity can be tuned from

−

19

∘

C to 16.0 °C. We measure the temperature fluctuation noise through modulation experiment, and it agrees well with the theoretical simulations. The vibrational sensitivities in three directions are measured to be around 10−11 /g–10−10 /g. The total weight of the system is 14.0 kg, with a volume of about 18 L, and the power dissipation of the electrical system is 18.6 W. Finally, the prototype of the space-borne laser shows a frequency instability of 9.5

×

10

−
16

at 0.2 s, and the frequency noise is measured to be 3.6 Hz/Hz1/2 at 6 mHz over three months, satisfying the mission targets of all current space gravitational wave detection programs.
Optical disc structures and diffraction patterns: theoretical foundations and experimental applications
Authors: Cheng Yuhang , Zhang Li , Zhang Yaping
Published: August 2024

This investigation advances the experimental exploration of optical discs’ diffraction phenomena, meticulously constructing optical pathways to ascertain the track pitch within the disc employing both transmission and reflection grating paradigms. Furthermore, this study devises a novel apparatus and methodology for the precise measurement of optical wavelengths, aiming to elucidate the intricate diffraction patterns and the underlying mechanisms of optical discs’ structure. This endeavor not only validates the methodological soundness and efficacy of the proposed approach but also pioneers new avenues for research into physics experiments leveraging optical discs. The application of optical discs in educational settings transcends traditional experimental pedagogy, fostering students’ capabilities to independently conceptualize experiments and delve into scientific explorations.
A derivation of the Schrödinger equation from Feynman’s path-integral formulation of quantum mechanics
Authors: Hendel Tal
Published: August 2024

The equation of motion in the standard formulation of non-relativistic quantum mechanics, the Schrödinger equation, is based on the Hamiltonian. In contrast, in Feynman’s path-integral formulation of quantum mechanics, the equation of motion is the propagation equation, which is based on the Lagrangian. That these two different equations of motion are equivalent was shown by Feynman, who provided a derivation of the Schrödinger equation from the propagation equation. Surprisingly, however, while in classical mechanics there exists a simple relationship between the Hamiltonian and the Lagrangian, there is nothing in Feynman’s derivation that gives any indication of this relationship. Here I show that the equations of motion in the Hamiltonian and Lagrangian formulations of quantum mechanics are, in fact, simply related to each other.
Additional applications of the Lambert W function to solid state physics
Authors: Houari Ahmed
Published: August 2024

Analytical solutions are always desirable in physics for the sake of mathematical exactness and physical insight. In this study, I obtain closed-form analytical expressions for various physical quantities taken from solid state physics. More precisely, I derive analytical expressions in terms of the Lambert W function for the work function and the field-enhancement factor of a field emitting material from the Fowler–Nordheim equation. Additionally, I derive similar analytical expressions for the localization length and the density of states in amorphous semiconductors from the Mott hopping conductivity. Similarly, I also derive analytical formulae based on the Lambert W function to compute the extrinsic-intrinsic transition temperature in a partially compensated semiconductor and the Kondo exchange coupling constant. All the obtained results are exact and explicit. Moreover, some of them allow a direct determination of some physical quantities of interest compared to their indirect determination from semi-logarithmic experimental plots. The findings of this paper are accessible and suitable for students enrolled in graduate solid state physics courses.
Visualization of electromagnetic fields in a circular waveguide using Mathematica
Authors: Song Ya-Ju , Chai Meng-Yao , Wang Xin-Wen , Yuan Ji-Bing , Tang Shi-Qing , Liu Yan
Published: August 2024

This paper employs Mathematica for visualizing electromagnetic fields (EMF) in circular waveguides, effectively addressing pedagogical challenges related to theoretical abstraction and computational complexity. We first derive the exact solutions for guided modes, then summarize the steps for visualizing EMF using Mathematica, propose educational strategies, and showcase simulation results. The Mathematica code is provided, allowing for dynamic parameter adjustment and real-time field change observation. This approach significantly enhances undergraduate students’ understanding of electromagnetism through engaging visual and interactive learning experiences.
Lattice dynamics of 119Sn impurity in a bcc-Cr crystal
Authors: Dubiel Stanisław M , Hu Michael Y , Sternik Małgorzata , Ercan Alp E , Alatas Ahmet , Said Ayman , Parlinski Krzysztof , Piekarz Przemysław
Published: August 2024

The chromium crystal doped with 119Sn isotope was studied using the nuclear resonance inelastic x-ray scattering and first principles calculations. The Sn partial phonon density of states (PDOS) was obtained for three temperatures that correspond to different magnetic states of Cr. At all temperatures, the energy spectrum consists of a broad band around 18 meV and a narrow peak at 43 meV. The additional peak around 39 meV is observed only in the magnetically ordered phases, indicating the influence of magnetic order in chromium on lattice dynamics. The partial PDOS calculated with the antiferromagnetic order on Cr atoms show a very good agreement with the experimental data. It is revealed that the high-energy peak is lying above the phonon spectra of the pure bcc-Cr crystal. These are the local modes with the increased energies due to a strongly reduced distance between Sn and the nearest-neighbor Cr atoms.
Hyperuniformity in Ashkin–Teller model
Authors: Mukherjee Indranil , Mohanty P K
Published: August 2024

We show that equilibrium systems in d dimension that obey the inequality

d
ν
>
2
,

known as Harris criterion, exhibit suppressed energy fluctuation in their critical state. Ashkin–Teller model is an example in d = 2 where the correlation length exponent ν varies continuously with the inter-spin interaction strength λ and exceeds the value

d
2

set by Harris criterion when λ is negative; there, the variance of the subsystem energy across a length scale l varies as

l

d
−
α

with hyperuniformity exponent

α
=
2
(
1
−

ν

−
1

)
.

Point configurations constructed by assigning unity to the sites which has coarse-grained energy beyond a threshold value also exhibit suppressed number fluctuation and hyperuniformiyty with same exponent

α
.
High spatiotemporal frame-straddling focusing schlieren imaging in a scramjet engine
Authors: Zhao Zhixin , Wang Xiaolong , Chen Mingjia , Wang Ze , Li Fan , Sun Mingbo , Zhu Jiajian , Zhou Bo
Published: August 2024

Flow visualization in harsh environments such as a scramjet combustor featuring highly turbulent supersonic reactive flow with intensive luminescence emission is challenging and typically lack of sufficient spatiotemporal resolution that is essential for resolving flow dynamics. This study presents a development of a robust flow visualization technique with an exceptional spatiotemporal resolution in a scramjet combustor. By utilizing a customized LED light source, the short pulse duration along with a high peak power and a single-color emission ensures an instantaneous exposure with little background luminescence interference. Focusing schlieren image measurements with mitigated path-integration effect are successfully demonstrated in a scramjet engine combustor at instant, frame-straddling, and sequential temporal resolutions of 100 ns, 500 ns, and 26 μs, respectively, along with a megapixel imaging resolution. Consequently, in addition to flow visualization, it is worth highlighting that the exceptional spatiotemporal correlation resolved by present measurements exhibits attractive potentials of velocimetry for harsh high-speed flow environments.
Adaptive horizon size moving horizon estimation with unknown noise statistical properties
Authors: Wang Zhongxin , Liu Zhilin , Yuan Shouzheng , Li Guosheng
Published: August 2024

Moving horizon estimation (MHE) is an effective technique for state estimation. It formulates state estimation as an optimization problem over a finite time interval and is characterized by inherent robustness, flexibility, and explicit constraint handling capabilities. The horizon size is a crucial parameter influencing the estimation performance of MHE. However, the selection of the horizon size remains an open research question in the field of MHE. In this paper, we propose a novel adaptive horizon size MHE strategy that dynamically adjusts the horizon size based on the value of the objective function. This approach aims to improve the state estimation performance of MHE in real-time applications. Unlike conventional MHE methods that rely on a fixed horizon size, our adaptive strategy enhances robustness against unknown noise statistics by adjusting the horizon size. We analyze the convergence property of the estimation error and provide guidelines for parameter design to ensure optimal performance. The effectiveness and superiority of the proposed method are demonstrated through simulations involving an oscillatory system and a target tracking application under non-stationary noise conditions.
A verified training support vector machine in bearing fault diagnosis
Authors: Liu Yuting , Gu Hong , Qin Pan
Published: August 2024

The combination of support vector machine (SVM) and deep learning is widely used in bearing fault diagnosis. The SVM-based bearing fault diagnosis method usually uses features extracted from bearing vibration signals as input. However, environmental noise in industrial applications can affect the feature representation, potentially leading to failures in SVM-based fault diagnosis methods. Adversarial robustness verification methods can evaluate the robustness of models to small perturbations in feature representations. Certified defense methods achieve robustness enhancement by embedding adversarial robustness verification into the learning process of the model. Thus, we propose a certified defense method named verified training SVM (VT-SVM) based on Lagrange duality. The proposed method incorporates adversarial robustness verification into the SVM learning framework, thereby enhancing the robustness of SVM in noisy environments. First, the certified defense optimization problem of SVM is constructed by combining the original optimization problem of SVM with the adversarial robustness verification problem. Then, the certified defense optimization problem is converted into an equivalent convex quadratic programming problem by introducing slack variables. Next, the Lagrange duality is used to transform the convex quadratic programming problem into a dual problem. Finally, the solution to the original optimization problem can be obtained by solving the dual problem. We validate the effectiveness of VT-SVM on the artificial dataset, the rolling bearing dataset from Case Western Reserve University, and the VBL-VA001 dataset from Sepuluh Nopember Institute of Technology. Experimental results demonstrate that our method both ensures high predictive performance and improves the resistance of the model to small noise.