bluuebunny/crossref_metadata_2025 huggingface dataset:
Recrystallization Behavior and Texture Evolution in Low Carbon Steel during Hot Deformation in Austenite/Ferrite Region
Authors: He Guoning , Peng Tianen , Jiang Bo , Hu Xuewen , Liu Yazheng , Wu Chunjing
Published: June 2021

Hot compression tests are carried out on low carbon steel with carbon content of 0.037 wt% over a temperature range of 900–700 °C. Stress–strain curves show that deformation resistance decreases from 870 to 820 °C and then increases. The temperatures of Ar3 and Ar1 are 873.8 and 796.4 °C, respectively, and the phase transformation speed reaches a maximum at 840 °C. The volume fractions of recrystallized grain, subgrain, and deformed grain are analyzed using optical microscope and electron back‐scattering diffraction. The distributions and the proportions of misorientation angles are also calculated. Textures are described using the inverse pole figure (IPF) colored orientation maps and orientation distribution functions (ODF). The results show that dynamic recrystallization (DRX) of austenite occurs to varying degrees during deformation in the austenite and double‐phase region. Dynamic recovery (DRV) of ferrite leads to the growth of ferrite grains in the double‐phase region. DRX of ferrite by the subgrain coalescence occurs at 700 °C. The main deformation textures in most of the double‐phase and single ferrite region are both cube texture. However, {112}<110> component has the highest texture intensity at 750 °C, reaching 5. The evolution mechanism of microstructure and texture is also discussed.
Ruthenium Complexes Featuring Unsymmetrical N‐Heterocyclic Carbene Ligands–Useful Olefin Metathesis Catalysts for Special Tasks
Authors: Monsigny Louis , Kajetanowicz Anna , Grela Karol
Published: June 2021

This review describes a distinct class of ruthenium olefin metathesis catalysts featuring unsymmetrical N‐heterocyclic carbene (uNHC) ligands, from its historical beginning to the present state of the art. Thanks to advantageous traits, such as pronounced thermodynamic stability, chemical latency, outstanding selectivity, and compatibility with green solvents, these catalysts led to good results in a number of specialized metathesis transformations. Therefore, while being a niche, the uNHC complexes can potentially be implemented in a number of industrial processes, such as valorization of Fischer‐Tropsch olefin fractions, ethenolysis of renewable products, and modern pharmaceutical production.
Genome‐wide association mapping of seedling and adult plant response to stem rust in a durum wheat panel
Authors: Megerssa Shitaye H. , Sorrells Mark E. , Ammar Karim , Acevedo Maricelis , Bergstrom Gary C. , Olivera Pablo , Brown‐Guedira Gina , Ward Brian , Degete Ashenafi G. , Abeyo Bekele
Published: June 2021

Many of the major stem rust resistance genes deployed in commercial wheat (Triticum spp.) cultivars and breeding lines become ineffective over time because of the continuous emergence of virulent races. A genome‐wide association study (GWAS) was conducted using 26,439 single nucleotide polymorphism (SNP) markers and 280 durum wheat [Triticum turgidum L. subsp. Durum (Desf.) Husnot] lines from CIMMYT to identify genomic regions associated with seedling resistance to races TTKSK, TKTTF, JRCQC, and TTRTF and field resistance to TKTTF and JRCQC. The phenotypic data analysis across environments revealed 61–91 and 59–77% of phenotypic variation was explained by the genotypic component for seedling and adult plant response of lines, respectively. For seedling resistance, mixed linear model (MLM) identified eight novel and nine previously reported quantitative trait loci (QTL) while a fixed and random model circulating probability unification (FarmCPU) detected 12 novel and eight previously reported QTL. For field resistance, MLM identified 12 novel and seven previously reported loci while FarmCPU identified seven novel and nine previously reported loci. The regions of Sr7a, Sr8155B1, Sr11, alleles of Sr13, Sr17, Sr22/Sr25, and Sr49 were identified. Novel loci on chromosomes 3B, 4A, 6A, 6B, 7A, and 7B could be used as sources of resistance to the races virulent on durum wheat. Two large‐effect markers on chromosome 6A could potentially be used to differentiate resistant haplotypes of Sr13 (R1 and R3). Allelism tests for Sr13, breaking the deleterious effect associated with Sr22/Sr25 and retaining the resistance allele at the Sr49 locus, are needed to protect future varieties from emerging races.
Ultrasonographic approach and findings in calves with hydranencephaly
Authors: Gorjidooz Morteza , Rahimabadi Peyman Dehghan , Raoofi Afshin , Masoudifard Majid , Mardjanmehr Seyed Hossein
Published: June 2021

Background

Teratogenic viral infections may proceed to hydranencephaly in cattle. Post‐mortem and antemortem diagnosis can be achieved by necropsy or ultrasonography, CT‐scan and MRI techniques.

Objectives

The aim of this study was to determine how effective ultrasonography approach is in detecting hydranencephaly in calves.

Methods

In this study, ultrasonography images were obtained from brains of nine Holstein claves, of the same age, with neurological signs (due to Akabane virus infection), approaching from the caudal part of the temporal bone. To confirm the obtained images, the same approach was used to obtain images from a normal calf of the same age. The thickness of the temporal bone was measured and compared in seven affected and the healthy calves, using CT‐scan images.

Results

In ultrasonographic images, temporal bone (as a hyperechoic structure) and temporal cortical mantle (as an echogenic structure) were noted in the right and left side of the skull. The medial part of the image showed presence of fluid in an anechoic region, instead of brain parenchyma. Falx cerebri was also seen as a floating hyperechoic line in the middle part in all patients. There was no statistically significant difference between the thickness of temporal bone in normal and affected calves (p = 0.502). All findings were confirmed by necropsy.

Conclusions

Transtemporal approach is a novel and easy approach to study the brain in calves. This is the first study on the hydranencephalic brains of claves, using ultrasonography by transtemporal approach.
Use of a polyethylene glycol solution for the management of sand impaction in three dogs
Authors: Johnson Randi , Wigglesworth Samantha , Moyle Rachel , Lynch Alex
Published: June 2021

Three dogs were hospitalized for management of acute gastrointestinal signs secondary to sand impaction. Hospitalized care with administration of a polyethylene glycol (PEG) solution via nasogastric tube. Variable PEG solution doses were used in these dogs (range 72–109 ml/kg). All patients tolerated PEG administration without adverse effects. Two dogs had additional radiographs performed, consistent with radiographic improvement of impaction. Each dog had marked clinical improvement and was successfully discharged from the hospital.
An Homage to Otto Stern
Authors: Herschbach Dudley
Published: June 2021

This chapter outlines an International Symposium held at Frankfurt on 1–5 September 2019. It marked the centennial of quantitative experiments with molecular beams, pioneered by Otto Stern. The European Physical Society declared Stern’s original laboratory a Historic Site, the fifth in Germany. As a graduate student in 1955, I learned about Otto Stern (1888–1969) and the impact of his molecular beams on quantum physics. I was intrigued and undertook crossed-beam experiments at Berkeley. In 1960 Otto came to a seminar that I gave. Later I met him, and heard some of his stories. The rest of the chapter describes his Nobel Prize and other Fests. In 1958 his long-term colleague, Immanuel Estermann, organized a celebration and Festschrift for Otto’s 70th birthday. In 1988, as a guest editor, I organized a Festschift for the centennial of Otto’s birth. That year, the German Physical Society established the Stern-Gerlach Prize as its highest award for experimental physics. Bretislav Friedrich and I wrote three papers about Stern. Since 2000, Horst Schmidt-Böcking at Frankfurt and colleagues have produced historical articles, along with a book about Otto, edited and bound all of his research papers into books, and diligently pursued letters to and from Otto, collecting them into large volumes.
Wilhelm Heinrich Heraeus—Doctoral Student at the University Frankfurt
Authors: Jorda S. , Schmidt-Böcking H.
Published: June 2021

Wilhelm Heinrich Heraeus (*1900 – †1985), the founder of the Wilhelm and Else Heraeus Foundation, wrote his doctoral thesis at the University of Frankfurt in 1922–23 under the supervision of Richard Wachsmuth and Walther Gerlach. Thereby, he became a witness of the Stern-Gerlach experiment, completed in Frankfurt in 1922. In his thesis, Heraeus investigated “The dependence of the thermoelectrical force of iron on its structure” and was able to show that earlier measurements by G. Borelius were incorrect and irreproducible. On 23 July 1923, Heraeus passed his doctoral examination in Frankfurt under Wachsmuth’s auspices.
Quantum or Classical Perception of Atomic Motion
Authors: Briggs John S.
Published: June 2021

An assessment is given as to the extent to which pure unitary evolution, as distinct from environmental decohering interaction, can provide the transition necessary for an observer to perceive quantum dynamics as classical. This has implications for the interpretation of quantum wavefunctions as a characteristic of ensembles or of single particles and the related question of wavefunction “collapse”. A brief historical overview is presented as well as recent emphasis on the role of the semi-classical “imaging theorem” in describing quantum to classical unitary evolution.
The Precision Limits in a Single-Event Quantum Measurement of Electron Momentum and Position
Authors: Schmidt-Böcking H. , Eckart S. , Lüdde H. J. , Gruber G. , Jahnke T.
Published: June 2021

A modern state-of-the-art “quantum measurement” [The term “quantum measurement” as used here implies that parameters of atomic particles are measured that emerge from a single scattering process of quantum particles.] of momentum and position of a single electron at a given time [“at a given time” means directly after the scattering process. (It should be noticed that the duration of the reaction process is typically extremely short => attoseconds).] and the precision limits for their experimental determination are discussed from an experimentalists point of view. We show—by giving examples of actually performed experiments—that in a single reaction between quantum particles at a given time only the momenta of the emitted particles but not their positions can be measured with sub-atomic resolution. This fundamental disparity between the conjugate variables of momentum and position is due to the fact that during a single-event measurement only the total momentum but not position is conserved as function of time. We highlight, that (other than prevalently perceived) Heisenberg’s “Uncertainty Relation” UR [1] does not limit the achievable resolution of momentum in a single-event measurement. Thus, Heisenberg’s statement that in a single-event measurement only either the position or the momentum (velocity) of a quantum particle can be measured with high precision contradicts a real experiment. The UR states only a correlation between the mean statistical fluctuations of a large number of repeated single-event measurements of two conjugate variables. A detailed discussion of the real measurement process and its precision with respect to momentum and position is presented.
Precision Physics in Penning Traps Using the Continuous Stern-Gerlach Effect
Authors: Blaum Klaus , Werth Günter
Published: June 2021

“A single atomic particle forever floating at rest in free space” (H. Dehmelt) would be the ideal object for precision measurements of atomic properties and for tests of fundamental theories. Such an ideal, of course, can ultimately never be achieved. A very close approximation to this ideal is made possible by ion traps, where electromagnetic forces are used to confine charged particles under well-controlled conditions for practically unlimited time. Concurrently, sensitive detection methods have been developed to allow observation of single stored ions. Various cooling methods can be employed to bring the trapped ion nearly to rest. Among different realisations of ion traps we consider in this chapter the so-called Penning traps which use static electric and magnetic fields for ion confinement. After a brief discussion of Penning-trap properties, we consider various experiments including the application of the “continuous Stern-Gerlach effect”, which have led recently to precise determinations of the masses and magnetic moments of particles and antiparticles. These serve as input for testing fundamental theories and symmetries.
Stern-Gerlach Interferometry with the Atom Chip
Authors: Keil Mark , Machluf Shimon , Margalit Yair , Zhou Zhifan , Amit Omer , Dobkowski Or , Japha Yonathan , Moukouri Samuel , Rohrlich Daniel , Binstock Zina , Bar-Haim Yaniv , Givon Menachem , Groswasser David , Meir Yigal , Folman Ron
Published: June 2021

In this invited review in honor of 100 years since the Stern-Gerlach (SG) experiments, we describe a decade of SG interferometry on the atom chip. The SG effect has been a paradigm of quantum mechanics throughout the last century, but there has been surprisingly little evidence that the original scheme, with freely propagating atoms exposed to gradients from macroscopic magnets, is a fully coherent quantum process. Specifically, no full-loop SG interferometer (SGI) has been realized with the scheme as envisioned decades ago. Furthermore, several theoretical studies have explained why it is a formidable challenge. Here we provide a review of our SG experiments over the last decade. We describe several novel configurations such as that giving rise to the first SG spatial interference fringes, and the first full-loop SGI realization. These devices are based on highly accurate magnetic fields, originating from an atom chip, that ensure coherent operation within strict constraints described by previous theoretical analyses. Achieving this high level of control over magnetic gradients is expected to facilitate technological applications such as probing of surfaces and currents, as well as metrology. Fundamental applications include the probing of the foundations of quantum theory, gravity, and the interface of quantum mechanics and gravity. We end with an outlook describing possible future experiments.
Inducing Enantiosensitive Permanent Multipoles in Isotropic Samples with Two-Color Fields
Authors: Ordonez Andres F. , Smirnova Olga
Published: June 2021

We find that two-color fields can induce field-free permanent dipoles in initially isotropic samples of chiral molecules via resonant electronic excitation in a one-$$3\omega $$

3
ω

-photon versus three-$$\omega $$
ω
-photons scheme. These permanent dipoles are enantiosensitive and can be controlled via the relative phase between the two colors. When the two colors are linearly polarized perpendicular to each other, the interference between the two pathways induces excitation sensitive to the molecular handedness and orientation, leading to uniaxial orientation of the excited molecules and to an enantio-sensitive permanent dipole perpendicular to the polarization plane. We also find that although a corresponding one-$$2\omega $$

2
ω

-photon versus two-$$\omega $$
ω
-photons scheme cannot produce enantiosensitive permanent dipoles, it can produce enantiosensitive permanent quadrupoles that are also controllable through the two-color relative phase.
Ultra-fast Dynamics in Quantum Systems Revealed by Particle Motion as Clock
Authors: Schöffler M. S. , Schmidt L. Ph. H. , Eckart S. , Dörner R. , Czasch A. , Jagutzki O. , Jahnke T. , Ullrich J. , Moshammer R. , Schuch R. , Schmidt-Böcking H.
Published: June 2021

To explore ultra-fast dynamics in quantum systems one needs detection schemes which allow time measurements in the attosecond regime. During the recent decades, the pump & probe two-pulse laser technique has provided milestone results on ultra-fast dynamics with femto- and attosecond time resolution. Today this technique is applied in many laboratories around the globe, since complete pump & probe systems are commercially available. It is, however, less known or even forgotten that ultra-fast dynamics has been investigated several decades earlier even with zeptosecond resolution in ion-atom collision processes. A few of such historic experiments, are presented here, where the particle motion (due to its very fast velocity) was used as chronometer to determine ultra-short time delays in quantum reaction processes. Finally, an outlook is given when in near future relativistic heavy ion beams are available which allow a novel kind of “pump & probe” experiments on molecular systems with a few zeptosecond resolution. However, such experiments are only feasible if the complete many-particle fragmentation process can be imaged with high momentum resolution by state-of-the-art multi-particle coincidence technique.
Manipulation and Control of Molecular Beams: The Development of the Stark-Decelerator
Authors: Meijer Gerard
Published: June 2021

State-selective manipulation of beams of atoms and molecules with electric and magnetic fields has been crucial for the success of the field of molecular beams. Originally, this manipulation only involved the transverse motion. In this Chapter, the development of the Stark-decelerator, that allows to also manipulate and control the longitudinal motion of molecules in a beam, is presented.
Quantum Effects in Cold and Controlled Molecular Dynamics
Authors: Koch Christiane P.
Published: June 2021

This chapter discusses three examples of quantum effects that can be observed in state-of-the-art experiments with molecular beams—scattering resonances as a probe of interparticle interactions in cold collisions, the protection of Fano-Feshbach resonances against decay despite resonant coupling to a scattering continuum, and a circular dichroism in photoelectron angular distributions arising in the photoionization of randomly oriented chiral molecules. The molecular beam setup provides molecules in well-defined quantum states. This, together with a theoretical description based on first principles, allows for excellent agreement between theoretical prediction and experimental observation and thus a rigorous understanding of the observed quantum effects.
From Hot Beams to Trapped Ultracold Molecules: Motivations, Methods and Future Directions
Authors: Fitch N. J. , Tarbutt M. R.
Published: June 2021

Over the past century, the molecular beam methods pioneered by Otto Stern have advanced our knowledge and understanding of the world enormously. Stern and his colleagues used these new techniques to measure the magnetic dipole moments of fundamental particles with results that challenged the prevailing ideas in fundamental physics at that time. Similarly, recent measurements of fundamental electric dipole moments challenge our present day theories of what lies beyond the Standard Model of particle physics. Measurements of the electron’s electric dipole moment (eEDM) rely on the techniques invented by Stern and later developed by Rabi and Ramsey. We give a brief review of this historical development and the current status of eEDM measurements. These experiments, and many others, are likely to benefit from ultracold molecules produced by laser cooling. We explain how laser cooling can be applied to molecules, review recent progress in this field, and outline some eagerly anticipated applications.
Otto Stern and Wave-Particle Duality
Authors: Peter Toennies J.
Published: June 2021

The contributions of Otto Stern to the discovery of wave-particle duality of matter particles predicted by de Broglie are reviewed. After a short introduction to the early matter-vs-wave ideas about light, the events are highlighted which lead to de Broglie’s idea that all particles, also massive particles, should exhibit wave behavior with a wavelength inversely proportional to their mass. The first confirming experimental evidence came for electrons from the diffraction experiments of Davisson and Germer and those of Thomson. The first demonstration for atoms, with three orders of magnitude smaller wave lengths, came from Otto Stern’s laboratory shortly afterwards in 1929 in a remarkabletour de forceexperiment. After Stern’s forced departure from Hamburg in 1933 it took more than 40 years to reach a similar level of experimental perfection as achieved then in Stern’s laboratory. Today He atom diffraction is a powerful tool for studying the atomic and electronic structure and dynamics of surfaces. With the advent of nanotechnology nanoscopic transmission gratings have led to many new applications of matter waves in chemistry and physics, which are illustrated with a few examples and described in more detail in the following chapters.
Grating Diffraction of Molecular Beams: Present Day Implementations of Otto Stern’s Concept
Authors: Schöllkopf Wieland
Published: June 2021

When Otto Stern embarked on molecular-beam experiments in his new lab at Hamburg University a century ago, one of his interests was to demonstrate the wave-nature of atoms and molecules that had been predicted shortly before by Louis de Broglie. As the effects of diffraction and interference provide conclusive evidence for wave-type behavior, Otto Stern and his coworkers conceived two matter-wave diffraction experiments employing their innovative molecular-beam method. The first concept assumed the molecular ray to coherently scatter off a plane ruled grating at grazing incidence conditions, while the second one was based on the coherent scattering from a cleaved crystal surface. The latter concept allowed Stern and his associates to demonstrate the wave behavior of atoms and molecules and to validate de Broglie’s formula. The former experiment, however, fell short of providing evidence for diffraction of matter waves. It was not until 2007 that the grating diffraction experiment was retried with a modern molecular-beam apparatus. Fully resolved matter-wave diffraction patterns were observed, confirming the viability of Otto Stern’s experimental concept. The correct explanation of the experiment accounts for quantum reflection, another wave effect incompatible with the particle picture, which was not foreseen by Stern and his contemporaries.
When Liquid Rays Become Gas Rays: Can Evaporation Ever Be Non-Maxwellian?
Authors: Nathanson Gilbert M.
Published: June 2021

A rare mistake by Otto Stern led to a confusion between density and flux in his first measurement of a Maxwellian speed distribution. This error reveals the key role of speed itself in Stern’s development of “the method of molecular rays”. What if the gas-phase speed distributions are not Maxwellian to begin with? The molecular beam technique so beautifully advanced by Stern can also be used to explore the speed distribution of gases evaporating from liquid microjets, a tool developed by Manfred Faubel. We employ liquid water and alkane microjets containing dissolved helium atoms to monitor the speed of evaporating He atoms into vacuum. While most dissolved gases evaporate in Maxwellian speed distributions, the He evaporation flux is super-Maxwellian, with energies up to 70% higher than the flux-weighted average energy of 2 RTliq. The explanation of this high-energy evaporation involves two beautiful concepts in physical chemistry: detailed balancing between He atom evaporation and condensation (starting with gas-surface collisions) and the potential of mean force on the He atom (starting with He atoms just below the surface). We hope that these measurements continue to fulfill Stern’s dream of the “directness and simplicity of the molecular ray method.”
My Great Uncle
Authors: Templeton Alan
Published: June 2021

When I was a child, my favorite relative without a doubt was my great uncle, Otto Stern, because he nearly always did exactly what he wanted, and he did very little else. Otto lived just 3 km away from us in a beautiful part of North Berkeley that is known for its fine views of San Francisco Bay, its pleasant prewar houses, and its many appealing gardens. I loved exploring Otto’s backyard because he left it completely untended. It gave me the feeling of walking into a fairy tale, far removed from the everyday world of rules and order.
Otto Stern’s Molecular Beam Method and Its Impact on Quantum Physics
Authors: Friedrich Bretislav , Schmidt-Böcking Horst
Published: June 2021

Motivated by his interest in thermodynamics and the emerging quantum mechanics, Otto Stern (1888–1969) launched in 1919 his molecular beam method to examine the fundamental assumptions of theory that transpire in atomic, molecular, optical, and nuclear physics. Stern’s experimental endeavors at Frankfurt (1919–1922), Hamburg (1923–1933), and Pittsburgh (1933–1945) provided insights into the quantum world that were independent of spectroscopy and that concerned well-defined isolated systems, hitherto accessible only toGedankenexperiments. In this chapter we look at how Stern’s molecular beam research came about and review six of his seminal experiments along with their context and reception by the physics community: the Stern-Gerlach experiment; the three-stage Stern-Gerlach experiment; experimental evidence for de Broglie’s matter waves; measurements of the magnetic dipole moment of the proton and the deuteron; experimental demonstration of momentum transfer upon absorption or emission of a photon; the experimental verification of the Maxwell-Boltzmann velocity distribution via deflection of a molecular beam by gravity. Regarded as paragons of thoroughness and ingenuity, these experiments entail accurate transversal momentum measurements with resolution better than 0.1 atomic units. Some of these experiments would be taken up by others where Stern left off only decades later (matter-wave scattering or photon momentum transfer). We conclude by highlighting aspects of Stern’s legacy as reflected by the honors that have been bestowed upon him to date.
Otto Stern—With Einstein in Prague and in Zürich
Authors: Gutfreund Hanoch
Published: June 2021

The two years that Otto Stern spent with Albert Einstein in Prague and Zürich, between the spring of 1912 and the spring of 1914, can be viewed as his apprenticeship in theoretical physics. This chapter describes that formative phase in Stern’s scientific career, prior to his emergence as one of the greatest innovators in experimental physics.
Our Enduring Legacy from Otto Stern
Authors: Kleppner Daniel
Published: June 2021

Otto Stern’s scientific legacy continues to animate discoveries on a rapidly advancing research frontier.
Walther Gerlach (1889–1979): Precision Physicist, Educator and Research Organizer, Historian of Science
Authors: Huber Josef Georg , Schmidt-Böcking Horst , Friedrich Bretislav
Published: June 2021

Walther Gerlach’s numerous contributions to physics include precision measurements related to the black-body radiation (1912–1916) as well as the first-ever quantitative measurement of the radiation pressure (1923), apart from his key role in the epochal Stern-Gerlach experiment (1921–1922). His wide-ranging research programs at the Universities of Tübingen, Frankfurt, and Munich entailed spectroscopy and spectral analysis, the study of the magnetic properties of matter, and radioactivity. An important player in the physics community already in his 20s and in the German academia in his later years, Gerlach was appointed, on Werner Heisenberg’s recommendation, Plenipotentiary for nuclear research for the last sixteen months of the existence of the Third Reich. He supported the effort of the German physicists to achieve a controlled chain reaction in a uranium reactor until the last moments before the effort was halted by the Allied Alsos Mission. The reader can find additional discussion of Gerlach’s role in the supplementary material provided with the online version of the chapter on SpringerLink. After returning from his detention at Farm Hall, he redirected his boundless elan and determination to the reconstruction of German academia. Among his high-ranking appointments in the Federal Republic were the presidency of the University of Munich (1948–1951) and of the Fraunhofer Society (1948–1951) as well as the vice-presidency of the German Science Foundation (1949–1961) and the German Physical Society (1956–1957). As a member of Göttinger Achtzehn, he signed the Göttingen Declaration (1957) against arming the Bundeswehr with nuclear weapons. Having made history in physics, Gerlach became a prolific writer on the history of physics. Johannes Kepler was his favorite subject and personal hero—as both a scientist and humanist.
100 Years Molecular Beam Method Reproduction of Otto Stern’s Atomic Beam Velocity Measurement
Authors: Gruppe Axel , Cerny Simon , Stiebing Kurt Ernst , George Cedric , Hoffmann Jakob , Ilg Maximilian , Müller Nils , Satar Alienza , Schobert Vincent , Weimer Leander , Dworak Markus , Engel Stefan , Rüschmann Gustav , Zimmer Viorica , Zanger Erich , Schmidt-Böcking Horst
Published: June 2021

The history of Otto Stern’s pioneering measurement of the Maxwell-Boltzmann velocity distribution of a Silver atomic beam performed 1919 in Frankfurt is described. It is shown how Albert Einstein influenced Stern in his research. This experimental apparatus is not any more existing; therefore it was reconstructed in the workshops of the Physics faculty of the Goethe University in Frankfurt. The experimental verification of Stern’s results was finally achieved by a team of Frankfurt high school students (Gymnasium Riedberg) under the supervision of their teachers Axel Gruppe and Simon Cerny. By fighting against a number of difficulties, they succeeded to get the reconstructed apparatus started and were able to reproduce the results from the early experiments of Stern.
Bound states of WIMP dark matter in Higgs-portal models. Part I. Cross-sections and transition rates
Authors: Oncala Ruben , Petraki Kalliopi
Published: June 2021

Abstract

We investigate the role of the Higgs doublet in the thermal decoupling of multi-TeV dark matter coupled to the Weak interactions of the Standard Model and the Higgs. The Higgs doublet can mediate a long-range force that affects the annihilation processes and binds dark matter into bound states. More importantly, the emission of a Higgs doublet by a pair of dark matter particles can give rise to extremely rapid monopole bound-state formation processes and bound-to-bound transitions. We compute these effects in the unbroken electroweak phase. To this end, we consider the simplest renormalisable fermionic model, consisting of a singlet and a doublet under SUL(2) that are stabilised by a ℤ2 symmetry, in the regime where the two multiplets coannihilate. In a companion paper, we use the results to show that the formation of metastable bound states via Higgs-doublet emission and their decay decrease the relic density very significantly.
On the Spectra of Separable 2D Almost Mathieu Operators
Authors: Takase Alberto
Published: June 2021

We consider separable 2D discrete Schrödinger operators generated by 1D almost Mathieu operators. For fixed Diophantine frequencies, we prove that for sufficiently small couplings the spectrum must be an interval. This complements a result by J. Bourgain establishing that for fixed couplings the spectrum has gaps for some (positive measure) Diophantine frequencies. Our result generalizes to separable multidimensional discrete Schrödinger operators generated by 1D quasiperiodic operators whose potential is analytic and whose frequency is Diophantine. The proof is based on the study of the thickness of the spectrum of the almost Mathieu operator and utilizes the Newhouse Gap Lemma on sums of Cantor sets.
Design optimization of aircraft structures using virtual proving ground
Authors: Gorskii Yuriy , Gavrilov Petr , Nikitin Georgiy , Pautova Tatiana , Tamm Aleksandr
Published: June 2021

The main challenges of aerospace industry are increased flight range, fuel, and operating costs. There is an urgent need for more efficient design methods and rational use of composite materials in order to reduce the weight of the aircraft and increase strength and reliability. The use of optimization methods, modern software, and supercomputer technologies plays a key role in shortening the product development cycle. It allows many design options to be analyzed and compared in the early design stages. This paper presents an approach to using optimization methods in conjunction with virtual tests. The Virtual Proving Ground (VPG) includes Virtual Testbeds (VTB) such as “Aerodynamics,” “Statics,” and “Dynamics.” VPG provides end-to-end transfer of results and boundary conditions between blocks and systems of automated post-processing of the results. Thus, the results of the aerodynamic tests are transferred as input data for the static strength tests. The results of static and dynamic tests allow to perform multicriterion optimization considering different loading conditions. Automated post-processing allows to track the miscellaneous parameters at every testing stage. The aim of this work is to develop an approach to optimization of a composite structures using VPG. The presented approach was developed and tested on the example of the unmanned aerial vehicle.
Reduced cortical GABA and glutamate in high schizotypy
Authors: Kozhuharova Petya , Diaconescu Andreea O. , Allen Paul
Published: June 2021

Rationale

Abnormal functioning of the inhibitory gamma-aminobutyric acid (GABA) and excitatory (glutamate) systems is proposed to play a role in the development of schizophrenia spectrum disorder. Although results are mixed, previous 1H-magnetic resonance spectroscopy (MRS) studies in schizophrenia and clinical high-risk samples report these metabolites are altered in comparison to healthy controls. Currently, however, there are few studies of these metabolites in schizotypy samples, a personality dimension associated with the experience of schizophrenia and psychosis-like symptoms.

Objectives

We investigated if GABA and glutamate metabolite concentrations are altered in people with high schizotypy. We also explored the relationship between resilience to stress, GABA metabolite concentrations and schizotypy.

Methods

We used MRS to examine GABA and glutamate levels in the medial prefrontal cortex in people with low and high schizotypy traits as assessed with the Schizotypal Personality Questionnaire. Resilience to stress was assessed using the Connor-Davidson Resilience Scale.

Results

Compared to individuals with low schizotypy traits, high schizotypy individuals showed lower cortical prefrontal GABA (F (1,38) = 5.18, p = 0.03, η2 = 0.09) and glutamate metabolite levels (F (1, 49) = 6.25, p = 0.02, η2 = 0.02). Furthermore, participants with high GABA and high resilience levels were significantly more likely to be in the low schizotypy group than participants with low GABA and high resilience or high GABA and low resilience (95% CI 1.07–1.34, p < .001).

Conclusions

These findings demonstrate that subclinical schizotypal traits are associated with abnormal functioning of both inhibitory and excitatory systems and suggest that these transmitters are implicated in a personality trait believed to be on a continuum with psychosis.
Effect of drying on the hydroxyl accessibility and sorption properties of pressurized hot water extracted wood
Authors: Kyyrö Suvi , Altgen Michael , Seppäläinen Hanna , Belt Tiina , Rautkari Lauri
Published: June 2021

Hot water extraction (HWE) treatment changes the physicochemical properties of the wood, including hygroscopic properties. HWE treatment decreases the hydroxyl accessibility of the wood, but the relevance of other mechanisms that change hygroscopic properties are not fully understood. This study investigates the effect of drying on the hydroxyl accessibility and sorption properties of wood. Pressurized hot water extraction (HWE) treatment was applied at 140 °C for 1–5 h to Scots pine (Pinus sylvestris L.) sapwood samples in order to remove increasingly more hemicellulose from the cell wall matrix. Following HWE treatment, half of the wood samples were oven-dried and then re-soaked, while the other half was kept in a fully saturated state. The samples were investigated by applying a new approach that was based on the deuteration of accessible hydroxyl groups, which was followed by the measurement of mass loss due to re-protonation. Sorption properties of the wood samples were studied by measuring moisture content, sorption isotherms and dimensional changes. The present results showed that accessible hydroxyl group content decreased only due to hemicellulose removal during the HWE treatment and was unaffected by oven-drying. However, oven-drying enhanced the effect of HWE treatments in reducing the water-saturated dimensions and the moisture content of wood. Therefore, the additional reductions in hygroscopicity and water-saturated dimensions were not related to changes in sorption site density.
Plastic responses in the coral Pocillopora acuta to extreme low-light conditions with and without food provision
Authors: Fong Jenny , Poquita-Du Rosa Celia , Todd Peter A.
Published: June 2021

This study examines phenotypically plastic responses inPocillopora acutacollected from a highly urbanized reef environment to extreme low-light conditions. While among-species differences in how corals cope with low light are well documented, much less is known about within-species responses. It also remains unclear how extreme low light and provision of food may interact and influence coral physiology. Clonal fragments from six colonies (genotypes) ofP. acutawere subjected to two light treatments with mean midday irradiances of 4 and 40 μmol photons m−2 s−1photosynthetically active radiation (PAR), representing just 0.5 and 5% ambient light level, and were either fed with zooplankton or not fed for nine days. Corals maintained in 4 PAR had lower endosymbiont density but higher cellular chlorophyllaconcentration than those in 40 PAR. Feeding rates were similar in both light treatments and had no significant effects on endosymbiont density and chlorophyllaconcentrations. While genotypes varied in the level of phenotypic plasticity expressed for both photoacclimation and heterotrophy, most displayed similar directions in their responses, indicating photoacclimation inP. acutais broadly predictable. Our study demonstrates thatP. acutafrom Singapore is able to acclimate to very low-light conditions by adjusting their photophysiology, providing additional evidence that this species is resilient to urbanization-related stress.
Exploring impacts of marine heatwaves: paternal heat exposure diminishes fertilization success in the purple sea urchin (Strongylocentrotus purpuratus)
Authors: Leach Terence S. , BuyanUrt Buyanzaya , Hofmann Gretchen E.
Published: June 2021

Marine heatwaves (MHWs) are projected to increase in intensity and frequency over the coming decades, and it is imperative to assess the adaptive capacity of marine organisms to these extreme temperature events. Given the nature of MHWs to last days to weeks in a region, these events may have overarching impacts on phenological events like reproduction and development. Here, the role of adult thermal history and transgenerational plasticity may be an important pathway by which MHWs are transduced to impact community structure. In this study, we sought to explore the effects of paternal thermal history in the purple urchin, Strongylocentrotus purpuratus, on a crucial aspect of reproduction, fertilization. Using ecologically relevant temperatures representative of both MHW events that occurred in 2014–2020 and non-MHW temperatures in our region of the California Large Marine Ecosystem, we conditioned male S. purpuratus for 28 days to either a high, MHW or a low, non-MHW temperature. Following the temperature acclimation of adults, sperm performance was tested for individual males by conducting fertilization success trials at varying temperatures and sperm concentrations. While sperm appeared robust to elevated temperature during fertilization, sperm produced by high-temperature-acclimated males had overall diminished performance as compared to those acclimated to non-MHW temperatures. These results suggest MHW events will have a negative impact on fertilization in situ for S. purpuratus populations. Furthermore, these results highlight the importance of considering both male and female environmental history in projections of reproduction under climate change scenarios.
Using complementary visual approaches to investigate residency, site fidelity and movement patterns of the dusky grouper (Epinephelus marginatus) in a Mediterranean marine protected area
Authors: Desiderà Elena , Trainito Egidio , Navone Augusto , Blandin Rémi , Magnani Luana , Panzalis Pieraugusto , Mazzoldi Carlotta , Guidetti Paolo
Published: June 2021

Assessing individuals’ abundance, residency (presence at a site within a certain period) and site fidelity (tendency to return to the same site in subsequent seasons or years) is crucial for evaluating and improving the effectiveness of spatial conservation/management measures regarding ecologically and socio-economically valuable species. Using underwater visual census (UVC) and photo-identification (photo-ID) techniques, we estimated the abundance, residency and site fidelity of the dusky grouper, Epinephelus marginatus, at two protected sites within the Tavolara-Punta Coda Cavallo Marine Protected Area (Sardinia, Italy) in the summers of 2017–2018. The scope and spatio-temporal resolution of the study was extended by involving volunteer recreational divers in the photo collection. Grouper mean densities varied significantly across sampling dates, with a significant variability between the 2 years and the two investigated sites. At least 94 grouper visited the study sites in the summers of 2017–2018 based on the analysis of 968 high-quality photos using a semi-automated software to photo-identify individuals. Overall, the most frequently sighted grouper was recorded on 32 different days and 21 individuals (22%) identified in 2017 were re-sighted in 2018. The participation of volunteer recreational divers helped detect the inter-site (3.5–4 km apart) movements of a female and a male, supporting previous findings regarding the occurrence of reproduction-related movements. This study provides novel insights into the residency and site-fidelity patterns of the dusky grouper, and its small-scale movements probably related to reproduction. Specifically, we provide indications that effective protection from fishing should encompass the entire area used by grouper for reproductive movements.
Exposure to moderately elevated temperatures changes food preferences in the tropical marine herbivore Haliotis squamata
Authors: Mitterwallner Veronika , Suci An Nisa Nurul , Zamani Neviaty , Lenz Mark
Published: June 2021

Ocean warming is affecting marine ectothermic herbivores as well as the macroalgal species they consume and this has the potential to alter their trophic interaction. However, it is currently still unknown how these two important components of benthic food webs will react to a warming environment. Consumption rates of grazers change with increasing temperatures, but it is unclear whether this is also true for feeding preferences. In this study, multiple-choice feeding assays with the tropical abalone Haliotis squamata from Western Indonesia were conducted in August 2018. After brief acclimation of either the grazer or the macroalgae to moderately elevated water temperatures (maximum 2 °C above the long-term average) in the laboratory, three species of living macroalgae were simultaneously offered to the abalone in feeding assays. Consumption rates of H. squamata were lower under elevated water temperatures, while its feeding preference switched: At 27 °C (2 °C below long-term average), abalone preferred non-acclimated Gracilaria salicornia, but switched to non-acclimated Amphiroa spp. at 31 °C. Interestingly, no such switch in preference occurred when the macroalgae, but not the grazers were acclimated. This indicates that the grazer will presumably be the driver of this potential change in interactions between H. squamata and its macroalgal food. Ocean warming may result in changes in the structure of benthic communities, mediated by changes in the feeding behaviour of herbivorous invertebrates.
The popliteofibular ligament: a cadaveric ultrasound study
Authors: Pękala Przemysław A. , Mizia Ewa , Mann Mitchell R. , Wagner-Olszewska Ilona , Mostowy Marcin , Tatoń Grzegorz , Domżalski Marcin
Published: June 2021

Objective

The popliteofibular ligament (PFL) is an important stabilizer of the knee found within the posterolateral corner (PLC) of the joint. Injuries to the PLC can cause substantial patient morbidity. Accurate PFL visualization has been historically challenging, impeding injury diagnosis and treatment. The gold standard for in vivo PFL visualization is magnetic resonance imaging (MRI), but this procedure has slice thickness limitations, is costly, and is subject to longer wait times. Ultrasonographic (US) PFL assessment is a potentially viable alternative to MRI. This study aimed to determine the viability of US PFL assessment.

Materials and methods

Ten fresh-frozen lower limb specimens were evaluated for the presence and morphometric characteristics of the PFL via US using an 18.0-MHz linear transducer. The cadavers were then dissected and reassessed for the presence and morphometric characteristics of the PFLs for comparison with US findings. Moreover, the fracture of the fibular styloid process near the site of the insertion of the PFL (the arcuate sign) was simulated and assessed via US.

Results

The PFL was visualized and measured in all ten knees via both US and cadaveric assessments. There were no statistically significant differences in PFL morphometric characteristics determined via US examination and dissection. The fibular styloid fracture was easily identified in US examination.

Conclusion

US imaging is a viable alternative for accurate and effective assessment of the normal PFL. Moreover, the arcuate sign can be evaluated via US.