bluuebunny/crossref_metadata_2025 huggingface dataset:
The effects of temperature and strain rate on the hot deformation behavior of AISI H10 tool steel
Authors: Ardakani Maryam Kamali , Morakabati Maryam
Published: December 2020

The hot deformation behavior of a H10 hot work tool steel was studied by performing hot compression tests over the temperature range of 900 to 1200 °C and strain rates of 0.001–1 s−1and total strain of 0.7. At temperatures below 1100 °C, the grain size is fine and below 20 μm. In this temperature range, grain size increase with temperature due to dissolution of carbides. Then by increasing temperature to 1150 and 1200 °C, the grain size is increased significantly due to growth of grains. The study on the effect of strain rate showed that at constant temperature of 1000 °C, the grain size increased from 4.8 to 6 μm with increasing strain rate from 0.001 to 1 s−1. Also, this increase in the strain rate at temperature of 1100 °C lead to increase the grain size from 5.9 to 17 μm, due to the occurrence of dynamic recrystallization. At 1200 °C growth of grains causes to decrease grain size from 112 to 87 μm by increasing strain rate. According to the microstructural investigations, at the temperatures of 1000 and 1100 °C and strain rates of 0.01 and 0.1 s−1dynamic recrystallization was the main softening mechanism. As a result, the most suitable range for hot deformation was obtained at the temperature range of 1000–1100 °C and strain rates of 0.01–0.1 s−1.
Effects of bottom plate in friction stir welding of AA6061-T6
Authors: Vinayagamoorthi M.A. , Prince M. , Balasubramanian S.
Published: December 2020

The effects of 40 mm width bottom plates on the microstructural modifications and the mechanical properties of a 6 mm thick FSW AA6061-T6 joint have been investigated. The bottom plates are placed partially at the weld zone to absorb and dissipate heat during the welding process. An axial load of 5 to 7 kN, a rotational speed of 500 rpm, and a welding speed of 50 mm/min are employed as welding parameters. The size of the nugget zone (NZ) and heat-affected zone (HAZ) in the weld joints obtained from AISI 1040 steel bottom plate is more significant than that of weld joints obtained using copper bottom plate due to lower thermal conductivity of steel. Also, the weld joints obtained using copper bottom plate have fine grain microstructure due to the dynamic recrystallization. The friction stir welded joints obtained with copper bottom plate have exhibited higher ductility of 8.9% and higher tensile strength of 172 MPa as compared to the joints obtained using a steel bottom plate.
Allocating fixed resources for DMUs with interval data
Authors: Sun Jiasen , Chen Meng , Fu Yelin , Luo Hao
Published: December 2020

Conventional DEA models tend to allocate the fixed resources to multiple decision-making units (DMUs) and treat the allocated resource as an extra input for every single DMU. However, the existing DEA resource allocation (DEA-RA) methods are applicable exclusively to the DMUs with exact values of inputs and outputs. A lack of precision for the input or output data of DMUs, such as the interval data, would cause a failure of the existing methods to allocate resources to DMUs. In order to resolve this problem, three DEA-RA models are proposed in this paper for different scenarios of decision-making. All of the proposed DEA-RA models are based on a set of common weights. Finally, the proposed models are empirically tested and validated through three examples. As revealed by the results, our proposed models are capable of providing a more fair and practical initial allocation scheme for decision makers.
Qualitätssicherung in der Patientenversorgung durch die Einarbeitung neuer Mitarbeiter in die Peritonealdialyse
Authors: Reichardt Michael
Published: December 2020

Der folgende Artikel ist eine Zusammenfassung einer Facharbeit im Rahmen der nephrologischen Fachweiterbildung zur Gesundheits- und Krankenpflegerin in der Nephrologie an der Weiterbildungsstätte nephrologischer Zentren Rhein-Ruhr am AKK in Essen von Kira Schiffer. Die Facharbeit widmet sich dem Thema der Qualitätssicherung in der Patientenversorgung durch die Einarbeitung neuer Mitarbeiter in die Peritonealdialyse (PD).
CT Features of COVID-19 Pneumonia Differ Depending on the Severity and Duration of Disease
Authors: Schaible Jan , Meiler Stefanie , Poschenrieder Florian , Scharf Gregor , Zeman Florian , Knobloch Charlotte , Rennert Janine , Pregler Benedikt , Kleine Henning , Menzel Cynthia , Stroszczynski Christian , Zorger Niels , Hamer Okka W
Published: December 2020

Background CT is important in the care of patients with COVID-19 pneumonia. However, CT morphology can change significantly over the course of the disease. To evaluate the CT morphology of RT-PCR-proven COVID-19 pneumonia in a German cohort with special emphasis on identification of potential differences of CT features depending on duration and severity of disease.

Method All patients with RT-PCR-proven COVID-19 pneumonia and chest CT performed between March 1 and April 15, 2020 were retrospectively identified. The CT scans were evaluated regarding the presence of different CT features (e. g. ground glass opacity, consolidation, crazy paving, vessel enlargement, shape, and margin of opacifications), distribution of lesions in the lung and extent of parenchymal involvement. For subgroup analyses the patients were divided according to the percentage of parenchymal opacification (0–33 %, 34–66 %, 67–100 %) and according to time interval between symptom onset and CT date (0–5 d, 6–10 d, 11–15 d, > 15 d). Differences in CT features and distribution between subgroups were tested using the Mantel-Haenszel Chi Squared for trend.

Results The frequency of CT features (ground glass opacity, consolidation, crazy paving, bronchial dilatation, vessel enlargement, lymphadenopathy, pleural effusion) as well as pattern of parenchymal involvement differed significantly depending on the duration of disease and extent of parenchymal involvement. The early phase of disease was characterized by GGO and to a lesser extent consolidation. The opacifications tended to be round and to some extent with sharp margins and a geographic configuration. The vessels within/around the opacifications were frequently dilated. Later on, the frequency of consolidation and especially crazy paving increased, and the round/geographic shape faded. After day 15, bronchial dilatation occurred, and lymphadenopathy and pleural effusion were seen more frequently than before.

Conclusion The prevalence of CT features varied considerably during the course of disease and depending on the severity of parenchymal involvement. Radiologists should take into account the time interval between symptom onset and date of CT and the severity of disease when discussing the likelihood of COVID-19 pneumonia based on CT morphology.

Key Points: 

Citation Format
Heroinintoxikationen: Risikofaktoren zur Notfallanamnese aus Expertensicht
Authors: Schneider Sven , Richter Christian , Niethammer Rainer , Beisel Larissa
Published: December 2020

Ziel der Studie Heroinintoxikationen nehmen in der Notfallmedizin seit Jahren den 1. Platz unter allen Drogennotfällen ein.

Methodik Zwischen April und Oktober 2019 wurden bundesweit 107 ExpertInnen aus 36 Einrichtungen in 23 Städten mit beruflichen Erfahrungen mit Heroinintoxikationen im Rahmen eines interdisziplinären und multiprofessionellen Rankingverfahrens zu den wichtigsten Risikofaktoren solcher Drogennotfälle befragt.

Ergebnisse Im Rahmen der Notfallanamnese sollten aus Expertensicht vor allem folgende Risikofaktoren berücksichtigt werden: Wiederaufnahme des Konsums nach längerer Abstinenz oder reduzierter Heroinaufnahme, Mischintoxikationen respektive Beikonsum von Benzodiazepinen, Alkohol, Pregabalin und/oder illegalen Drogen, Applikation, Menge und Reinheit des Heroins sowie ein akutes soziales Stressereignis.

Schlussfolgerung Unser Beitrag gibt Hinweise, welche Rahmenbedingungen der Notarzt im Rahmen der Notfallanamnese vor allem erfragen und dokumentieren sollte.
Late-Stage Transformation of Carboxylic Acids to N-Trifluoroethyl­imides with Trifluoromethyl Diazomethane
Authors: Hu Xiang-Guo , Qiu Xiao-Feng , Liu De-Yong , Zhang Wen-Feng
Published: December 2020

We report the first systematic evaluation of the reaction of trifluoromethyl diazomethane (2,2,2-trifluorodiazoethane, CF3CHN2) with drug-like molecules. We found our previous copper-catalyzed transformation of carboxylic acids to the corresponding N-trifluoro­ethylimides with CF3CHN2 and acetonitrile is well-suited for the late-stage modification of drug and drug-like acids. A procedure that enables the use of solid nitriles and nitriles with high boiling points as viable substrates is also disclosed.
Videosprechstunden: Gekommen, um zu bleiben
Authors: Kucera Martin
Published: December 2020

Die Verbreitung von Videosprechstunden ist maßgeblich von den Nöten der Pandemie getrieben. Angesichts der zweiten Welle nutzen auch immer mehr Kliniken deren Vorteile. Die Anbieter bauen darauf, dass dieser Gewöhnungseffekt Corona überdauern wird.
Elektronische Patientenakte: Die ePA kommt
Authors: Lang Michael
Published: December 2020

Ab dem nächsten Jahr erhalten Patienten die Möglichkeit, Gesundheitsdaten in einer elektronischen Akte zu führen und sie ihren Behandlern zur Verfügung zu stellen. Die Krankenhäuser sind bei ihren Vorbereitungen auf die ePA jedoch auf die Industrie angewiesen.
Versicherungen: Gut durch die Krise kommen
Authors: Lang Michael
Published: December 2020

Die Covid-19-Pandemie verändert die Arbeitsbedingungen in den Krankenhäusern und führt zu zusätzlichen Risiken für Mitarbeiter und Arbeitgeber. Ein Überblick zeigt, wie die Versicherer mit der neuen Situation umgehen.
DGIV Nachrichten: Die deutsche Gesundheitspolitik biegt auf die Zielgerade der Legislaturperiode
Authors: Kloepfer Albrecht
Published: December 2020

Das Gesundheitsversorgungs- und Pflegeverbesserungsgesetz (GVPG) wird wohl das letzte größere gesundheitspolitische Gesetzesvorhaben des Kabinetts Merkel IV. Enthalten sind verschiedenste Maßnahmen, die bisher „liegen geblieben“ sind. Aus der besonderen Perspektive der DGIV wird es, kurz nach unserem eigenen Jahreskongress am 30. Oktober, somit auch schon fast Zeit für eine Schlussbetrachtung der Amtszeit Jens Spahns. Wie steht es da um die Integrierte Versorgung?
Warm dense matter simulation via electron temperature dependent deep potential molecular dynamics
Authors: Zhang Yuzhi , Gao Chang , Liu Qianrui , Zhang Linfeng , Wang Han , Chen Mohan
Published: December 2020

Simulating warm dense matter that undergoes a wide range of temperatures and densities is challenging. Predictive theoretical models, such as quantum-mechanics-based first-principles molecular dynamics (FPMD), require a huge amount of computational resources. Herein, we propose a deep learning based scheme called electron temperature dependent deep potential molecular dynamics (TDDPMD), which can be readily applied to study larger systems with longer trajectories, yielding more accurate properties. We take warm dense beryllium (Be) as an example with the training data from FPMD simulations spanning a wide range of temperatures (0.4–2500 eV) and densities (3.50–8.25 g/cm3). The TDDPMD method well reproduces the principal Hugoniot curve and radial distribution functions from the FPMD method. Furthermore, it depicts the reflection point of the Hugoniot curve more smoothly and provides more converged diffusion coefficients. We also show the new model can yield static structure factors and dynamic structure factors of warm dense Be.
Dynamics in cortical activity revealed by resting-state MEG rhythms
Authors: Mendoza-Ruiz J. , Alonso-Malaver C. E. , Valderrama M. , Rosso O. A. , Martinez J. H.
Published: December 2020

The brain is a biophysical system subject to information flows that may be thought of as a many-body architecture with a spatiotemporal dynamics described by its neuronal structures. The oscillatory nature of brain activity allows these structures (nodes) to be described as a set of coupled oscillators forming a network where the node dynamics and that of the network topology can be studied. Quantifying its dynamics at various scales is an issue that claims to be explored for several brain activities, e.g., activity at rest. The resting-state (RS) associates the underlying brain dynamics of healthy subjects that are not actively compromised with sensory or cognitive processes. Studying its dynamics is highly non-trivial but opens the door to understand the general principles of brain functioning, as well as to contrast a passive null condition vs the dynamics of pathologies or non-resting activities. Here, we hypothesize about how the spatiotemporal dynamics of cortical fluctuations could be for healthy subjects at RS. To do that, we retrieve the alphabet that reconstructs the dynamics (entropy–complexity) of magnetoencephalography (MEG) signals. We assemble the cortical connectivity to elicit the dynamics in the network topology. We depict an order relation between entropy and complexity for frequency bands that is ubiquitous for different temporal scales. We unveiled that the posterior cortex conglomerates nodes with both stronger dynamics and high clustering for α band. The existence of an order relation between dynamic properties suggests an emergent phenomenon characteristic of each band. Interestingly, we find the posterior cortex as a domain of dual character that plays a cardinal role in both the dynamics and structure regarding the activity at rest. To the best of our knowledge, this is the first study with MEG involving information theory and network science to better understand the dynamics and structure of brain activity at rest for different bands and scales.
Vibrationally resolved coupled-cluster x-ray absorption spectra from vibrational configuration interaction anharmonic calculations
Authors: Moitra Torsha , Madsen Diana , Christiansen Ove , Coriani Sonia
Published: December 2020

Vibrationally resolved near-edge x-ray absorption spectra at the K-edge for a number of small molecules have been computed from anharmonic vibrational configuration interaction calculations of the Franck–Condon factors. The potential energy surfaces for ground and core-excited states were obtained at the core-valence separated CC2, CCSD, CCSDR(3), and CC3 levels of theory, employing the adaptive density-guided approach scheme to select the single points at which to perform the energy calculations. We put forward an initial attempt to include pair-mode coupling terms to describe the potential of polyatomic molecules.
A general implementation of time-dependent vibrational coupled-cluster theory
Authors: Madsen Niels Kristian , Jensen Andreas Buchgraitz , Hansen Mads Bøttger , Christiansen Ove
Published: December 2020

The first general excitation level implementation of the time-dependent vibrational coupled cluster (TDVCC) method introduced in a recent publication [J. Chem. Phys. 151, 154116 (2019)] is presented. The general framework developed for time-independent vibrational coupled cluster (VCC) calculations has been extended to the time-dependent context. This results in an efficient implementation of TDVCC with general coupling levels in the cluster operator and Hamiltonian. Thus, the convergence of the TDVCC[k] hierarchy toward the complete-space limit can be studied for any sum-of-product Hamiltonian. Furthermore, a scheme for including selected higher-order excitations for a subset of modes is introduced and studied numerically. Three different definitions of the TDVCC autocorrelation function (ACF) are introduced and analyzed in both theory and numerical experiments. Example calculations are presented for an array of systems including imidazole, formyl fluoride, formaldehyde, and a reduced-dimensionality bithiophene model. The results show that the TDVCC[k] hierarchy converges systematically toward the full-TDVCC limit and that the implementation allows accurate quantum-dynamics simulations of large systems to be performed. Specifically, the intramolecular vibrational-energy redistribution of the 21-dimensional imidazole molecule is studied in terms of the decay of the ACF. Furthermore, the importance of product separability in the definition of the ACF is highlighted when studying non-interacting subsystems.
Manipulation of single cells inside nanoliter water droplets using acoustic forces
Authors: Gerlt Michael S. , Haidas Dominik , Ratschat Alexandre , Suter Philipp , Dittrich Petra S. , Dual Jürg
Published: December 2020

Droplet microfluidics enables high-throughput screening of single cells and is particularly valuable for applications, where the secreted compounds are analyzed. Typically, optical methods are employed for analysis, which are limited in their applicability as labeling protocols are required. Alternative label-free methods such as mass spectrometry would broaden the range of assays but are harmful to the cells, which is detrimental for some applications such as directed evolution. In this context, separation of cells from supernatant is beneficial prior to the analysis to retain viable cells. In this work, we propose an in-droplet separation method based on contactless and label-free acoustic particle manipulation. In a microfluidic chip, nanoliter droplets containing particles are produced at a T-junction. The particles are trapped in the tip of the droplet by the interplay of acoustic forces in two dimensions and internal flow fields. The droplets are subsequently split at a second T-junction into two daughter droplets—one containing the supernatant and the other containing the corresponding particles. The separation efficiency is measured in detail for polystyrene (PS) beads as a function of droplet speed, size, split ratio, and particle concentration. Further, single-bead (PS) and single-cell (yeast) experiments were carried out. At a throughput of 114 droplets/min, a separation efficiency of 100% ± 0% was achieved for more than 150 droplets. Finally, mammalian cells and bacteria were introduced into the system to test its versatility. This work demonstrates a robust, non-invasive strategy to perform single yeast cell-supernatant sampling in nanoliter volumes.
General elephants for threefold extremal contractions with one-dimensional fibres: exceptional case
Authors: Mori S. , Prokhorov Yu. G.
Published: December 2020

Let

be a germ of a threefold

with terminal singularities along a connected reduced complete curve

with a contraction

such that

and

is

-ample. Assume that each irreducible component of

contains at most one point of index

. We prove that a general member

is a normal surface with Du Val singularities.

Bibliography: 16 titles.
Uniform convergence criterion for non-harmonic sine series
Authors: Oganesyan K. A.
Published: December 2020

We show that for a nonnegative monotonic sequence

the condition

is sufficient for the series

to converge uniformly on any bounded set for

, and for any odd

it is sufficient for it to converge uniformly on the whole of

. Moreover, the latter assertion still holds if we replace

by any polynomial in odd powers with rational coefficients. On the other hand, in the case of even

it is necessary that

for the above series to converge at the point

or at

. As a consequence, we obtain uniform convergence criteria. Furthermore, the results for natural numbers

remain true for sequences in the more general class

.

Bibliography: 17 titles.
Der Tod bei Plotin und Plotins Tod in derVita Plotinides Porphyrios
Authors: Hammann Christoph
Published: December 2020

Dieser Beitrag geht der Frage nach, ob zwischen den Schriften Plotins und derVita Plotinides Porphyrios im Hinblick auf das Verständnis des Todes und die Annahme der Unsterblichkeit der Seele eine Kohärenz zu erkennen ist. Dafür wird im ersten Teil zunächst anhand derEnneadengezeigt, was Plotin für sterblich erachtet, wie Plotin den konkreten Vorgang des Sterbens versteht, welche Hintergründe Plotin für Ewigkeit und für Sterblichkeit annimmt, welche Konsequenzen die Bindung der Seele an den Körper nach Plotin für die Seele hat und wie sich aus Plotins Sicht die Trennung der Seele vom Körper auf das Leben der Seele auswirkt. Im zweiten Teil wird anhand derVita Plotinigezeigt, dass die Darstellung, die Porphyrios von Plotins Tod und der Existenz von Plotins Seele nach dem Tod bietet, mit Plotins Konzeption im Wesentlichen übereinstimmt.
Bontia daphnoides (white alling).
Authors: Vélez-Gavilán Jeanine
Published: December 2020

Bontia daphnoides is a shrub species native to the Caribbean and South America, which has been introduced to Cuba and the USA. B. daphnoides is considered invasive in Cuba, but Oviedo Prieto et al. (2006) provide conflicting information about the species occurrence in the country. They report it as only rarely seen in mangroves in the west part of the country, but later in the same document they list it as invasive in that same area. More information is needed to determine the invasiveness of this species in Cuba. The species is not considered invasive in the two states where it has been introduced in the USA (Florida and Hawaii).
Bixa orellana (annatto).
Authors: Ventosa Eduardo
Published: December 2020

B. orellana is a shrub or small tree which was one of the first American plants to be introduced into southern Asia and tropical Africa and soon became naturalized in these areas and in the East Indies (Morton, 1960). It is recognized as an exotic species in the Lesser and Greater Antilles. In Puerto Rico and the Virgin Islands it is considered to be naturalized (Acevedo-Rodríguez and Strong 2012). It is listed as invasive principally on Pacific islands, although a risk assessment considers it as low risk in the region (PIER, 2015).
Relational Commitment toward a Partner in Prison: An Investment Model Analysis
Authors: Stockman Dagmar , Uzieblo Kasia , Verhofstadt Lesley
Published: December 2020

The present study aimed to examine the underlying mechanisms of why partners of detainees remain in their relationships and whether this mechanism is associated with the number of monthly visits made to the imprisoned partner. The Investment Model Scale was used to assess: commitment, relationship satisfaction, relationship alternatives, and relationship investments in a sample of one hundred female partners of detainees (M = 35.9 years). As expected, satisfaction was positively and alternatives negatively associated with commitment and commitment was positively related to the number of visits. These results may inform prison initiatives aimed at supporting relationship maintenance.
SNAP23 deficiency causes severe brain dysplasia through the loss of radial glial cell polarity
Authors: Kunii Masataka , Noguchi Yuria , Yoshimura Shin-ichiro , Kanda Satoshi , Iwano Tomohiko , Avriyanti Erda , Atik Nur , Sato Takashi , Sato Ken , Ogawa Masaharu , Harada Akihiro
Published: December 2020

In the developing brain, the polarity of neural progenitor cells, termed radial glial cells (RGCs), is important for neurogenesis. Intercellular adhesions, termed apical junctional complexes (AJCs), at the apical surface between RGCs are necessary for cell polarization. However, the mechanism by which AJCs are established remains unclear. Here, we show that a SNARE complex composed of SNAP23, VAMP8, and Syntaxin1B has crucial roles in AJC formation and RGC polarization. Central nervous system (CNS)–specific ablation of SNAP23 (NcKO) results in mice with severe hypoplasia of the neocortex and no hippocampus or cerebellum. In the developing NcKO brain, RGCs lose their polarity following the disruption of AJCs and exhibit reduced proliferation, increased differentiation, and increased apoptosis. SNAP23 and its partner SNAREs, VAMP8 and Syntaxin1B, are important for the localization of an AJC protein, N-cadherin, to the apical plasma membrane of RGCs. Altogether, SNARE-mediated localization of N-cadherin is essential for AJC formation and RGC polarization during brain development.
Tracking Confirmation
Authors: Douven Igor
Published: December 2020

Confirmation is a graded notion: evidence can confirm a hypothesis to a greater or lesser degree. There has been debate about how to measure degree of confirmation. Starting from the observation that we would like evidence to be a discriminating indicator of truth, we conduct computer simulations to determine how well the various known measures of confirmation predict the extent to which a given piece of evidence fulfills that role, given a hypothesis of interest. The outcomes show that some measures are markedly better indicators of truth than others.
Supplementary comparison EURAMET.EM-S42, comparison of lightning impulse (LI) reference measuring systems
Authors: Hällström J , Elg A-P , Havunen J , Garnacho F
Published: December 2020

Main text

In 2016 the Consultative Committee for Electricity and Magnetism (CCEM) commissioned a supplementary comparison EURAMET.EM-S42 of Lightning Impulse (LI) measurement systems. This comparison was piloted by RISE (Sweden, formerly SP), and it was supported by VTT MIKES (Finland) and FFII LCOE (Spain). Eleven National Metrology Institutes (NMI) and two Designated Institutes (DI) from four Regional Metrology Organizations, EURAMET, COOMET, APMP and SIM, took part in the comparison.

A commercial travelling measuring system (TRMS) for Lightning Impulse (LI) measurement was adopted for the comparison. The TRMS consisted of a 700 kV resistive voltage divider and a transient recorder with computer. The TRMS was calibrated by the pilot lab in November 2016 before start of the comparison, and the first circulation was between five EURAMET NMI/DIs. After an intermediate calibration by the pilot lab in July 2017, the TRMS was circulated between seven NMI/DIs in the other regional organisations. On the return of the TRMS in March 2019 a final calibration was made by the pilot lab.

The measured parameters are defined in IEC60060-1. Test voltage value (U
t), front time (T
1), time to half value (T
2) and relative overshoot (β') were measured for full impulses; and extreme value (U
e) and time to chopping (T
c) for front chopped waveform. The test voltage value ranged from -700 kV to 700 kV with two full and one chopped impulse waveform. A set of preferred voltage levels and waveforms was defined. The obtained expanded uncertainties (k = 2) of the comparison reference values (CRV) were: <0.3% for U
t, <1.3% for T
1, <1.0% for T
2, <0.4% for β', <0.6% for U
e and <1.4% for T
c.

The transfer reference measuring system of the previous LI comparison (EU-SMT4-CT98-2270), arranged between 1999 and 2002, is linked to this comparison. The link is established by comparing VTT MIKES system used 20 years ago with that used in this comparison.

To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/.

The final report has been peer-reviewed and approved for publication by the CCEM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).
Update of the BIPM comparison BIPM.RI(II)-K1.Ag-110m of activity measurements of the radionuclide 110mAg to include the 2015 result of the PTB (Germany)
Authors: Michotte C , Courte S , Nonis M , Coulon R , Judge S , Ratel G , Kossert K , Nähle O
Published: December 2020

Main text

Since 1983, 6 laboratories have submitted 7 samples of 110mAg to the International Reference System (SIR) for activity comparison at the Bureau International des Poids et Mesures (BIPM), with comparison identifier BIPM.RI(II)-K1.Ag-110m. Recently, the PTB (Germany) participated in the comparison and the key comparison reference value (KCRV) has been updated. The degrees of equivalence between each equivalent activity measured in the SIR and the updated KCRV have been calculated and the results are given in the form of a table. A graphical presentation is also given.

To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/.

The final report has been peer-reviewed and approved for publication by the CCRI, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).
Controllable photon extraction based on a single-photon Raman interaction
Authors: Hu Yu , He Shu , Zhang Yuanwei , Yuan Haidong , Liu W M , Yan Cong-Hua
Published: December 2020

A target whispering-gallery-mode microresonator (WGMM) directly coupled to a waveguide with an auxiliary side-coupled WGMM is proposed to deterministically extract both the resonant and non-resonant single incident photons from a waveguide. Based on the single-photon Raman interaction (SPRINT) between an Λ-type three-level atom and the target WGMM, a full quantum theory in real space is adopted to calculate the extraction efficiencies at the single-photon level. The results show that the extraction efficiencies can be significantly improved by appropriately tuning the frequencies of the auxiliary WGMM and the coupling strength between the two WGMMs, even when the atom and WGMMs have dissipations. Since mode redistribution is only externally imposed on the auxiliary WGMM, the population and phase of the atom are not directly affected. The nonlocal control, which ensures that the SPRINT takes place, results in high extraction efficiencies. We also find that the transmission probabilities of both the resonant and non-resonant incident photons can be controlled in a range from 0 to 100%, so that the proposed double-WGMM system has the potential to be used as a single-photon switch.
Monte Carlo simulation of resonance effects of electron transport in a spatially modulated electric field in Ar, N2 and their mixtures
Authors: Albert A , Bošnjaković D , Dujko S , Donkó Z
Published: December 2020

The relaxation of the distribution function of the electrons drifting under the influence of a homogeneous electric field in noble gases is known to take place over an extended spatial domain at ‘intermediate’ values of the reduced electric field, E/N. We investigate the transport of electrons in Ar and N2 gases, as well as in their mixtures at such E/N values (∼10–40 Td). After discussing briefly the basic scenario of relaxation in a homogeneous electric field, the major part of work concentrates on the properties of transport in an electric field that is spatially modulated within a finite region that obeys periodic boundaries. The spatial distribution of the mean velocity, the mean energy, and the density of the electrons, the importance of the excitation channels, as well as the electron energy distribution function are obtained from Monte Carlo simulations for various lengths of the computational domain, at different mean values and degrees of modulation of the reduced electric field. At low modulations, the spatial profiles of the mean velocity and mean energy are nearly harmonic, however their phases with respect to the electric field perturbation exhibit a complex behaviour as a function of the parameters. With increasing modulation, an increasing higher harmonic content of these profiles is observed and at high modulations where an electric field reversal occurs, we observe trapping of a significant population of the electrons. The effect of mixing a molecular gas, N2, to Ar on the transport characteristics is also examined. Transition to local transport at high N2 admixture concentrations and long spatial domains is observed.
Large power dissipation of hot Dirac fermions in twisted bilayer graphene
Authors: Kubakaddi S S
Published: December 2020

We have carried out a theoretical investigation of hot electron power loss P, involving electron–acoustic phonon interaction, as a function of twist angle θ, electron temperature T
e and electron density n
s in twisted bilayer graphene. It is found that as θ decreases closer to magic angle θ
m, P enhances strongly and θ acts as an important tunable parameter, apart from T
e and n
s. In the range of T
e = 1–50 K, this enhancement is ∼250–450 times the P in monolayer graphene (MLG), which is manifestation of the great suppression of Fermi velocity v
F
* of electrons in moiré flat band. As θ increases away from θ
m, the impact of θ on P decreases, tending to that of MLG at θ ∼ 3°. In the Bloch–Grüneisen (BG) regime, P ∼ T
e
4, n
s
−1/2 and v
F
*−2. In the higher temperature region (∼10–50 K), P ∼ T
e

δ
, with δ ∼ 2.0, and the behavior is still super linear in T
e, unlike the phonon limited linear-in-T (lattice temperature) resistivity ρ
p. P is weakly, decreasing (increasing) with increasing n
s at lower (higher) T
e, as found in MLG. The energy relaxation time τ
e is also discussed as a function of θ and T
e. Expressing the power loss P = F
e(T
e) − F
e(T), in the BG regime, we have obtained a simple and useful relation F
e(T)μ
p(T) = (ev
s
2/2) i.e. F
e(T) = (n
s
e
2
v
s
2/2)ρ
p, where μ
p is the acoustic phonon limited mobility and v
s is the acoustic phonon velocity. The ρ
p estimated from this relation using our calculated F
e(T) is nearly agreeing with the ρ
p of Wu et al (2019 Phys. Rev. B
99 165112).
Parameter identification of micron-sized freestanding stretchable electronic interconnects using integrated digital height correlation
Authors: Kleinendorst S M , Shafqat S , Geers M G D , Hoefnagels J P M
Published: December 2020

For the development of reliable stretchable electronic systems, it is essential to comprehend and predict their mechanical behavior. It is important to test and analyze original as-processed samples, as opposed to standard tests on bulk material. Dedicated analysis methods are necessary for obtaining the material properties from the tests, as complex 3D deformations complicate the use of existing methods. This paper presents an integrated digital height correlation (IDHC) method for the mechanical characterization of a recently developed ultra-stretchable freestanding interconnect. Height maps from an out-of-plane loading experiment are correlated to a numerical model, with the aim to identify the material parameters in the plastic regime. The IDHC method is tested on a virtual test case, where it is shown that the algorithm converges for the considered three plasticity parameters. For the real experiment, simultaneous correlation of all three parameters is not possible due to an inherently flat residual landscape with many local minima. However, the initial yield strength and hardening exponent were still identified and estimated at 225–300 MPa and 0.15–0.2 respectively. Despite the moderate accuracy of the identification, the potency of the IDHC method for this extremely challenging case of micron-sized delicate freestanding stretchable electronic interconnects is demonstrated.
Development of a coupled simulation toolkit for computational radiation biology based on Geant4 and CompuCell3D
Authors: Liu Ruirui , Higley Kathryn A , Swat Maciej H , Chaplain Mark A J , Powathil Gibin G , Glazier James A
Published: December 2020

Understanding and designing clinical radiation therapy is one of the most important areas of state-of-the-art oncological treatment regimens. Decades of research have gone into developing sophisticated treatment devices and optimization protocols for schedules and dosages. In this paper, we presented a comprehensive computational platform that facilitates building of the sophisticated multi-cell-based model of how radiation affects the biology of living tissue. We designed and implemented a coupled simulation method, including a radiation transport model, and a cell biology model, to simulate the tumor response after irradiation. The radiation transport simulation was implemented through Geant4 which is an open-source Monte Carlo simulation platform that provides many flexibilities for users, as well as low energy DNA damage simulation physics, Geant4-DNA. The cell biology simulation was implemented using CompuCell3D (CC3D) which is a cell biology simulation platform. In order to couple Geant4 solver with CC3D, we developed a ‘bridging’ module, RADCELL, that extracts tumor cellular geometry of the CC3D simulation (including specification of the individual cells) and ported it to the Geant4 for radiation transport simulation. The cell dose and cell DNA damage distribution in multicellular system were obtained using Geant4. The tumor response was simulated using cell-based tissue models based on CC3D, and the cell dose and cell DNA damage information were fed back through RADCELL to CC3D for updating the cell properties. By merging two powerful and widely used modeling platforms, CC3D and Geant4, we delivered a novel tool that can give us the ability to simulate the dynamics of biological tissue in the presence of ionizing radiation, which provides a framework for quantifying the biological consequences of radiation therapy. In this introductory methods paper, we described our modeling platform in detail and showed how it can be applied to study the application of radiotherapy to a vascularized tumor.
Complementary relation between quantum entanglement and entropic uncertainty
Authors: Cao Yun , Wang Dong , Fan Xiao-Gang , Ming Fei , Wang Zhang-Yin , Ye Liu
Published: December 2020

Quantum entanglement is regarded as one of the core concepts, which is used to describe the non-classical correlation between subsystems, and entropic uncertainty relation plays a vital role in quantum precision measurement. It is well known that entanglement of formation can be expressed by von Neumann entropy of subsystems for arbitrary pure states. An interesting question is naturally raised: is there any intrinsic correlation between the entropic uncertainty relation and quantum entanglement? Or if the relation can be applied to estimate the entanglement. In this work, we focus on exploring the complementary relation between quantum entanglement and the entropic uncertainty relation. The results show that there exists an inequality relation between both of them for an arbitrary two-qubit system, and specifically the larger uncertainty will induce the weaker entanglement of the probed system, and vice versa. Besides, we use randomly generated states as illustrations to verify our results. Therefore, we claim that our observations might offer and support the validity of using the entropy uncertainty relation to estimate quantum entanglement.
A neurophysiological approach to spatial filter selection for adaptive brain–computer interfaces
Authors: Bennett James D , John Sam E , Grayden David B , Burkitt Anthony N
Published: December 2020

Objective. The common spatial patterns (CSP) algorithm is an effective method to extract discriminatory features from electroencephalography (EEG) to be used by a brain–computer interface (BCI). However, informed selection of CSP filters typically requires oversight from a BCI expert to accept or reject filters based on the neurophysiological plausibility of their activation patterns. Our goal was to identify, analyze and automatically classify prototypical CSP patterns to enhance the prediction of motor imagery states in a BCI. Approach. A data-driven approach that used four publicly available EEG datasets was adopted. Cluster analysis revealed recurring, visually similar CSP patterns and a convolutional neural network was developed to distinguish between established CSP pattern classes. Furthermore, adaptive spatial filtering schemes that utilize the categorization of CSP patterns were proposed and evaluated. Main results. Classes of common neurophysiologically probable and improbable CSP patterns were established. Analysis of the relationship between these categories of CSP patterns and classification performance revealed discarding neurophysiologically improbable filters can decrease decoder performance. Further analysis revealed that the spatial orientation of EEG modulations can evolve over time, and that the features extracted from the original CSP filters can become inseparable. Importantly, it was shown through a novel adaptive CSP technique that adaptation in response to these emerging patterns can restore feature separability. Significance. These findings highlight the importance of considering and reporting on spatial filter activation patterns in both online and offline studies. They also emphasize to researchers in the field the importance of spatial filter adaptation in BCI decoder design, particularly for online studies with a focus on training users to develop stable and suitable brain patterns.
Maize yield loss risk under droughts in observations and crop models in the United States
Authors: Leng Guoyong
Published: December 2020

The negative drought impacts on crop yield are well recognized in the literature, but are evaluated mainly in a deterministic manner. Considering the randomness feature of droughts and the compounding effects of other factors, we hypothesize that droughts effects on yields are probabilistic especially for assessment in large geographical regions. Taking US maize yield as an example, we found that a moderate, severe, extreme and exceptional drought event (based on the standardized precipitation evapotranspiration index) would lead to a yield loss risk (i.e. the probability of yield reduction lower than expected value) of 64.3%, 69.9%, 73.6%, and 78.1%, respectively, with hotspots identified in Central and Southeastern US. Irrigation has reduced yield loss risk by 10%–27%, with the benefit magnitude depending on the drought intensity. Evaluations of eight process crop models indicate that they can well reproduce observed drought risks for the country as a whole, but show difficult in capturing the spatial distribution patterns. The results highlight the diverse risk pattern in response to a drought event of specific intensity, and emphasize the need for better representation of drought effects in process models at local scales. The analysis framework developed in this study is novel in that it allows for an event-based assessment of drought effects in a risk manner in both observations and process crop models. Such information is valuable not only for robust decision-makings but also for the insurance sector, which typically require the risk information rather than a single value of outcome especially given the uncertainty of drought effects.
Dual index properties of photonic crystal and its application in subwavelength focusing
Authors: Liang Bingming , Ji Jing , Tang Dawei , Huang Yan , Huang Xiao
Published: December 2020

Based on the two-dimensional dielectric wedge-shaped photonic crystal, we studied the existence of two kinds of equivalent refractive indexes (negative refractive index is −1, positive refractive index is 1.897) in the photonic crystal by means of fast Fourier transform (FFT), as well as its influence on the optical propagation characteristics was discussed. By adjusting the wedge angle of the photonic crystal to eliminate the influence of positive refraction beam on the imaging, the sub wavelength focusing with half-width less than half of a wavelength can be realized. The numerical results show that the Full Width Half Maximum (FWHM) of the image point can reach a minimum of

0.41
λ

when the wedge angle of the photonic crystal is 73°.
On the frequency spectra of the electrostatic upper hybrid wave and linear Landau damping in a weakly magnetized relativistic electron plasma
Authors: Noureen S , Abbas Gohar , Sarfraz M , James L
Published: December 2020

On the basis of Vlasov-Kinetic model and using Maxwell-Juttner distribution function, dispersion relation of electrostatic wave in a collisionless homogeneous relativistic electron plasma is derived. The analysis of the oscillation spectra is carried out in a weak magnetic field limit

ω
−

kv

th

≥ Ω. Approximate analytic expression for the weakly damped mode is obtained in the subluminal limiting range. It is shown that the relativistic weakly damped mode can be estimated analytically in the range where the wave phase velocity v

φ
becomes greater than relativistic thermal velocity of the electron but less than speed of light. Results in the non-relativistic and the ultrarelativistic cases are also discussed.
Atomic permutationally invariant polynomials for fitting molecular force fields
Authors: Allen Alice E A , Dusson Geneviève , Ortner Christoph , Csányi Gábor
Published: December 2020

We introduce and explore an approach for constructing force fields for small molecules, which combines intuitive low body order empirical force field terms with the concepts of data driven statistical fits of recent machine learned potentials. We bring these two key ideas together to bridge the gap between established empirical force fields that have a high degree of transferability on the one hand, and the machine learned potentials that are systematically improvable and can converge to very high accuracy, on the other. Our framework extends the atomic permutationally invariant polynomials (aPIP) developed for elemental materials in (2019 Mach. Learn.: Sci. Technol.
1 015004) to molecular systems. The body order decomposition allows us to keep the dimensionality of each term low, while the use of an iterative fitting scheme as well as regularisation procedures improve the extrapolation outside the training set. We investigate aPIP force fields with up to generalised 4-body terms, and examine the performance on a set of small organic molecules. We achieve a high level of accuracy when fitting individual molecules, comparable to those of the many-body machine learned force fields. Fitted to a combined training set of short linear alkanes, the accuracy of the aPIP force field still significantly exceeds what can be expected from classical empirical force fields, while retaining reasonable transferability to both configurations far from the training set and to new molecules.
Human versus Computer Partner in the Paired Oral Discussion Test
Authors: Ockey Gary J , Chukharev-Hudilainen Evgeny
Published: December 2020

A challenge of large-scale oral communication assessments is to feasibly assess a broad construct that includes interactional competence. One possible approach in addressing this challenge is to use a spoken dialog system (SDS), with the computer acting as a peer to elicit a ratable speech sample. With this aim, an SDS was built and four trained human raters assessed the discourse elicited from 40 test takers that completed a paired oral task with both a human and a computer partner. The test takers were evaluated based on the analytic operational oral communication rating scales which included interactional competence, fluency, pronunciation, and grammar/vocabulary. Repeated-measures ANOVA indicated that fluency, pronunciation, and grammar and vocabulary were scored similarly across the two conditions, while interactional competence was scored substantially higher in the human partner condition. A g-study indicated that the computer partner was more reliable in assessing interactional competence, and rater questionnaire and interview data suggested the computer provided a more standardized assessment. Conversely, raters generally favored the human partner, in part because of its perceived authenticity and naturalness.