bluuebunny/crossref_metadata_2025 huggingface dataset:
Variance Measures for Symmetric Positive (Semi-) Definite Tensors in Two Dimensions
Authors: Herberthson Magnus , Özarslan Evren , Westin Carl-Fredrik
Published: February 2021

Calculating the variance of a family of tensors, each represented by a symmetric positive semi-definite second order tensor/matrix, involves the formation of a fourth order tensor $$R_{abcd}$$

R

abcd

. To form this tensor, the tensor product of each second order tensor with itself is formed, and these products are then summed, giving the tensor $$R_{abcd}$$

R

abcd

the same symmetry properties as the elasticity tensor in continuum mechanics. This tensor has been studied with respect to many properties: representations, invariants, decomposition, the equivalence problem et cetera. In this paper we focus on the two-dimensional case where we give a set of invariants which ensures equivalence of two such fourth order tensors $$R_{abcd}$$

R

abcd

and $$\widetilde{R}_{abcd}$$

R
~

abcd

. In terms of components, such an equivalence means that components $$R_{ijkl}$$

R

ijkl

of the first tensor will transform into the components $$\widetilde{R}_{ijkl}$$

R
~

ijkl

of the second tensor for some change of the coordinate system.
Continuous Histograms for Anisotropy of 2D Symmetric Piece-Wise Linear Tensor Fields
Authors: Masood Talha Bin , Hotz Ingrid
Published: February 2021

In this chapter we present an accurate derivation of the distribution of scalar invariants with quadratic behavior represented as continuous histograms. The anisotropy field, computed from a two-dimensional piece-wise linear tensor field, is used as an example and is discussed in all details. Histograms visualizing an approximation of the distribution of scalar values play an important role in visualization. They are used as an interface for the design of transfer-functions for volume rendering or feature selection in interactive interfaces. While there are standard algorithms to compute continuous histograms for piece-wise linear scalar fields, they are not directly applicable to tensor invariants with non-linear, often even non-convex behavior in cells when applying linear tensor interpolation. Our derivation is based on a sub-division of the mesh in triangles that exhibit a monotonic behavior. We compare the results to a naïve approach based on linear interpolation on the original mesh or the subdivision.
Postcolonial Reflections on the Mnemonic Confluence of the Holocaust, Stalinist Crimes, and Colonialism
Authors: Lim Jie-Hyun
Published: February 2021

Lim sets out the origins and progress of the mnemonic confluence of three historical traumas—the Holocaust, the crimes of colonialism, and Stalinist terror. He traces this process back to the “thaw” in memory cultures precipitated by the end of socialism after 1989, and adopts a postcolonial perspective to analyze how victimhood memories arising out of these experiences have become entangled globally. Against the flat model of the cosmopolitanization of the Holocaust, Lim argues for the non-hierarchical comparability of historical traumas. He concludes by proposing “critical relativization” and “radical juxtaposition” as ways of de-hegemonizing and de-centering universal memories and deconstructing mnemonic nationalism.
Öffentliche Mobilität und neue Mobilitätsdienstleistungen – Rahmenbedingungen und Gestaltungsperspektiven
Authors: Wolking Christina
Published: February 2021

Der Mobilitätssektor befindet sich in einem umfassenden Transformationsprozess. Gesellschaftliche Makroentwicklungen, wie die Urbanisierung, Individualisierung, demographischer Wandel und Digitalisierung, eröffnen neue Möglichkeiten, führen aber andererseits auch zu erweiterten Anforderungen an das Mobilitätssystem. Die veränderten Rahmenbedingungen auf übergeordneter Ebene stoßen einen Wandel in Hinblick auf das Mobilitätsverhalten, auf das Mobilitätsangebot, aber auch auf die Leitbilder und Strategien der Politik an. Die Debatte um eine Verkehrswende verdeutlicht die Notwendigkeit von Veränderungen des Verkehrssystems. Durch den kontinuierlich hohen Anteil an den Treibhausgasemissionen in Deutschland kommt dem Verkehrssektor, als zweitgrößter Emittent nach der Energiewirtschaft, eine entscheidende Rolle im Kampf gegen den Klimawandel zu.
Extracting Hawking radiation near the horizon of AdS black holes
Authors: Saraswat Krishan , Afshordi Niayesh
Published: February 2021

Abstract

We study how the evaporation rate of spherically symmetric black holes is affected through the extraction of radiation close to the horizon. We adopt a model of extraction that involves a perfectly absorptive screen placed close to the horizon and show that the evaporation rate can be changed depending on how close to the horizon the screen is placed. We apply our results to show that the scrambling time defined by the Hayden-Preskill decoding criterion, which is derived in Pennington’s work (arXiv:1905.08255) through entanglement wedge reconstruction is modified. The modifications appear as logarithmic corrections to Pennington’s time scale which depend on where the absorptive screen is placed. By fixing the proper distance between the horizon and screen we show that for small AdS black holes the leading order term in the scrambling time is consistent with Pennington’s scrambling time. However, for large AdS black holes the leading order Log contains the Bekenstein-Hawking entropy of a cell of characteristic length equal to the AdS radius rather than the entropy of the full horizon. Furthermore, using the correspondence between the radial null energy condition (NEC) and the holographic c-theorem, we argue that the screen cannot be arbitrarily close to the horizon. This leads to a holographic argument that black hole mining using a screen cannot significantly alter the lifetime of a black hole.
Entanglement spectrum of geometric states
Authors: Guo Wu-zhong
Published: February 2021

Abstract

The reduced density matrix of a given subsystem, denoted by ρA, contains the information on subregion duality in a holographic theory. We may extract the information by using the spectrum (eigenvalue) of the matrix, called entanglement spectrum in this paper. We evaluate the density of eigenstates, one-point and two-point correlation functions in the microcanonical ensemble state ρA,m associated with an eigenvalue λ for some examples, including a single interval and two intervals in vacuum state of 2D CFTs. We find there exists a microcanonical ensemble state with λ0 which can be seen as an approximate state of ρA. The parameter λ0 is obtained in the two examples. For a general geometric state, the approximate microcanonical ensemble state also exists. The parameter λ0 is associated with the entanglement entropy of A and Rényi entropy in the limit n → ∞. As an application of the above conclusion we reform the equality case of the Araki-Lieb inequality of the entanglement entropies of two intervals in vacuum state of 2D CFTs as conditions of Holevo information. We show the constraints on the eigenstates. Finally, we point out some unsolved problems and their significance on understanding the geometric states.
Bark proportion of Scots pine industrial wood
Authors: Berendt Ferréol , Pegel Erik , Blasko Lubomir , Cremer Tobias
Published: February 2021

Bark characteristics are not only used in the forest-wood supply chain, for example to calculate standing volumes, but also to transform wood volumes and masses. In this study, bark thickness, bark volume and bark mass were analyzed on the basis of 150 Scots pine discs, with a mean diameter of 13 cm. The mean double bark thickness was 3.02 mm, the mean bark volume proportion was 5.6% and mean bark mass proportion was 3.3%. Bark proportions were significantly affected by the log-specific variables ‘diameter over bark’, ‘proportion of bark damage’ and ‘double bark thickness’.
Spondylodiszitis und epiduraler Abszess
Authors: Rotzinger R. , Omidi R. , Gebhard H. , Shariat K. , Ahlhelm F.
Published: February 2021

Klinisches/methodisches Problem

Die Spondylodiszitis ist eine Entzündung der intervertebralen Bandscheibe, die beim Erwachsenen aufgrund der Vaskularisation in der Regel mit einer Spondylitis der angrenzenden Wirbelkörper einhergeht und klinisch häufig nur unspezifische Symptome wie Rücken- oder Nackenschmerzen zeigt. Sie kann erregerassoziiert von verschiedenen Pathogenen, v. a. Bakterien, verursacht werden. Dabei können ein oder mehrere Bewegungssegmente betroffen sein. Die Infektion kann epidurale Abszedierungen verursachen und sich auch auf umliegende Kompartimente ausbreiten. Die Radiologie, und hier insbesondere die Magnetresonanztomographie (MRT), spielt eine wichtige Rolle bei der Primärdiagnostik und im Rahmen von Verlaufsbeurteilungen zur Überprüfung des Therapieansprechens. Die Therapie beruht auf konservativen (Antibiotika) und invasiven Ansätzen, einschließlich einer Operation. Die interventionelle Punktion und Drainage ist v. a. in frühen Stadien der Abszessbildung eine vielversprechende Alternative.

Radiologische Standardverfahren

Magnetresonanztomographie (MRT), Computertomographie (CT), nuklearmedizinische Verfahren, konventionelles Röntgen.

Leistungsfähigkeit

Die MRT hat den höchsten Stellenwert. CT und nuklearmedizinische Verfahren können ergänzend und im Fall bestehender Kontraindikationen zur MRT eingesetzt werden.

Schlussfolgerung

Bei adäquater Diagnostik und Therapie hat die Spondylodiszitis eine gute Prognose. Neben der gezielten bzw. kalkulierten medikamentösen Therapie steht beim epiduralen Abszess die invasive Therapie im Vordergrund. Die interventionell-radiologische Punktion und Drainage (auch zur Keimidentifikation für die gezielte Antibiotikatherapie) können frühzeitig eine schonende Alternative zur chirurgischen Sanierung darstellen.
The carbon isotopic signature of C4 crops and its applicability in breeding for climate resilience
Authors: Eggels Stella , Blankenagel Sonja , Schön Chris-Carolin , Avramova Viktoriya
Published: February 2021

Key message

Carbon isotope discrimination is a promising trait for indirect screening for improved water use efficiency of C4crops.

In the context of a changing climate, drought is one of the major factors limiting plant growth and yield. Hence, breeding efforts are directed toward improving water use efficiency (WUE) as a key factor in climate resilience and sustainability of crop production. As WUE is a complex trait and its evaluation is rather resource consuming, proxy traits, which are easier to screen and reliably reflect variation in WUE, are needed. In C3crops, a trait established to be indicative for WUE is the carbon isotopic composition (δ13C) of plant material, which reflects the preferential assimilation of the lighter carbon isotope12C over13C during photosynthesis. In C4crops, carbon fixation is more complex and δ13C thus depends on many more factors than in C3crops. Recent physiological and genetic studies indicate a correlation between δ13C and WUE also in C4crops, as well as a colocalization of quantitative trait loci for the two traits. Moreover, significant intraspecific variation as well as a medium to high heritability of δ13C has been shown in some of the main C4crops, such as maize, sorghum and sugarcane, indicating its potential for indirect selection and breeding. Further research on physiological, genetic and environmental components influencing δ13C is needed to support its application in improving WUE and making C4crops resilient to climate change.
The influence of cut direction and process parameters in wire electrical discharge machining of carbon fibre–reinforced plastic composites
Authors: Abdallah Ramy , Soo Sein Leung , Hood Richard
Published: February 2021

The paper details a comprehensive experimental investigation on the influence of operating parameters and cut direction (parallel and perpendicular to fibre orientation) when wire electrical discharge machining (WEDM) unidirectional CFRP composites using zinc-coated brass wire (0.25-mm diameter). A Taguchi L18 fractional factorial orthogonal array considering four variable parameters including open voltage, ignition current and pulse-on time as well as pulse-off time was carried out for each cut direction. Results showed that a ~ 16% increase in maximum material removal rate was achieved when machining parallel to fibre direction (2.41 mm3/min) compared to cutting perpendicular to the fibres (~ 2.08 mm3/min), which was attributed to the higher electrical conductivity of the workpiece along the fibre length leading to greater discharge energies. This however resulted in relatively larger average kerf widths and poorer workpiece surface roughness (Sa) caused by the Joule heating effect. Workpieces machined parallel to fibre direction were generally free of any major edge defects, in contrast to severe delamination observed on both the top and bottom surfaces of specimens cut perpendicular to fibre orientation. High-magnification scanning electron microscopy of the machined surfaces revealed the presence of adhered resin material, fibre cracking, cavities/gaps in the matrix phase and interlayer cracks on most of the samples analysed, with damage severity dependent on the operating parameters and cut direction.
Repeatable differences in exploratory behaviour predict tick infestation probability in wild great tits
Authors: Rollins Robert E. , Mouchet Alexia , Margos Gabriele , Chitimia-Dobler Lidia , Fingerle Volker , Becker Noémie S. , Dingemanse Niels J.
Published: February 2021

Ecological factors and individual-specific traits affect parasite infestation in wild animals. Ixodid ticks are important ectoparasites of various vertebrate hosts, which include passerine bird species such as the great tit (Parus major). We studied various key ecological variables (breeding density, human disturbance) and phenotypic traits (exploratory behaviour, body condition) proposed to predict tick infestation probability and burden in great tits. Our study spanned 3 years and 12 nest box plots located in southern Germany. Breeding, adult great tits were assessed for exploration behaviour, body condition, and tick burden. Plots were open to human recreation; human disturbance was quantified in each plot as a recreation pressure index from biweekly nest box inspections. Infested individuals were repeatable in tick burden across years. These repeatable among-individual differences in tick burden were not attributable to exploration behaviour. However, faster explorers did have a higher infestation probability. Furthermore, body condition was negatively correlated to tick burden. Recreation pressure was correlated to increased infestation probability, although this relationship was just above the threshold of statistical significance. Our study implies that avian infestation probability and tick burden are each determined by distinct phenotypic traits and ecological factors. Our findings highlight the importance of animal behaviour and human disturbance in understanding variation in tick burden among avian hosts.

Significance statement

Various abiotic and biotic factors, including personality type, influence tick parasitism in birds, but exactly how all these factors interplay remains unclear. We studied a wild population of great tits over a 3-year period and assessed birds for their exploration behaviour and tick infestation. We found that more explorative great tits were more likely to be infested with ticks. By contrast, faster explorers did not have higher tick burdens. Tick burden was nevertheless moderately repeatable among individuals. Our results imply that animal personality influences the probability of parasite infestation, and that infestation likelihood versus intensity are determined by distinct mechanisms. Our work highlights the importance of animal behaviour to understand parasite infestation in wild populations.
Infection threat shapes our social instincts
Authors: Kramer Peter , Bressan Paola
Published: February 2021

We social animals must balance the need to avoid infections with the need to interact with conspecifics. To that end we have evolved, alongside our physiological immune system, a suite of behaviors devised to deal with potentially contagious individuals. Focusing mostly on humans, the current review describes the design and biological innards of this behavioral immune system, laying out how infection threat shapes sociality and sociality shapes infection threat. The paper shows how the danger of contagion is detected and posted to the brain; how it affects individuals’ mate choice and sex life; why it strengthens ties within groups but severs those between them, leading to hostility toward anyone who looks, smells, or behaves unusually; and how it permeates the foundation of our moral and political views. This system was already in place when agriculture and animal domestication set off a massive increase in our population density, personal connections, and interaction with other species, amplifying enormously the spread of disease. Alas, pandemics such as COVID-19 not only are a disaster for public health, but, by rousing millions of behavioral immune systems, could prove a threat to harmonious cohabitation too.
Spiky-joint: a bioinspired solution to combine mobility and support
Authors: Khaheshi Ali , Gorb Stanislav N. , Rajabi Hamed
Published: February 2021

Mobility and support are two structural properties that are often mutually exclusive. However, combining them could enhance the performance of mechanical components, and offer novel technical applications. Here through the implementation of a bioinspired interlocking mechanism in the design of a supportive, yet mobile, wrist splint, we tackled the conflicting combination of the two properties. We elaborated our design into a technology readiness level and, using 3D printing, directly converted it into a real-life application. In contrast to the existing splints, our bioinspired splint supports human wrist without impairing its movements. Hence, it can be used to prevent hyperextension injuries without hindering wrist function. By being interlocked at the maximum wrist extension, our splint could be an ideal wrist support for athletes, especially weightlifters. By restricting the wrist mobility, it could also be used as a support device to treat less severe medical issues, such as sprain, strain, or even for the recovery after cast removal, during which full immobilization may result in muscle atrophy. Our design strategy is purely structural; hence, it can be easily modified and implemented in other engineering applications. The simple, yet efficient, solution developed in this study offers a universal paradigm for developing engineering systems that pursuit both mobility and support.

Graphic abstract
Clinicopathological characteristics and outcomes in men with mesothelioma of the tunica vaginalis testis: analysis of published case-series data
Authors: Grogg Josias Bastian , Fronzaroli Jordi Nicola , Oliveira Pedro , Bode Peter-Karl , Lorch Anja , Issa Allaudin , Beyer Joerg , Eberli Daniel , Sangar Vijay , Hermanns Thomas , Clarke Noel William , Fankhauser Christian Daniel
Published: February 2021

Purpose

Mesothelioma of the tunica vaginalis testis (MTVT) is a rare tumor, and currently, there are no published treatment recommendations.

Methods

We performed a systematic literature review and synthesized clinical presentation, clinicopathological factors associated with metastatic disease, treatment options, and outcomes in men with MTVT.

Results

We included 170 publications providing data on 275 patients. Metastatic disease occurred in 84/275 (31%) men with malignant MTVT: Most common sites included retroperitoneal lymph nodes (LNs) (40/84, 48%), lungs (30/84, 36%), and inguinal LNs (23/84, 27%).

Invasion of the spermatic cord or scrotum was the only risk factor for local recurrence [odds ratio (OR) 3.21, 95% confidence interval (CI) 1.36–7.57]. Metastatic disease was associated with age ≥ 42 years (OR 3.02, 95% CI 1.33–6.86), tumor size ≥ 49 mm (OR 6.17, 95% CI 1.84–20.74), presence of necrosis (OR 8.31, 95% CI 1.58–43.62), high mitotic index (OR 13.36, 95% CI 1.53–116.51) or angiolymphatic invasion (OR 3.75, 95% CI 1.02–13.80), and local recurrence (OR 4.35, 95% CI 2.00–9.44). Complete remission in the metastatic setting was observed in five patients, most of whom were treated with multimodal therapy. Median survival in patients with metastatic disease was 18 months (IQR 7–43).

Conclusion

Malignant MTVT is a rare but aggressive disease. Since local recurrence is a risk factor for metastatic progression, we recommend aggressive local treatment. Survival and response to any treatment in the metastatic setting are limited.
On-chip trainable hardware-based deep Q-networks approximating a backpropagation algorithm
Authors: Kim Jangsaeng , Kwon Dongseok , Woo Sung Yun , Kang Won-Mook , Lee Soochang , Oh Seongbin , Kim Chul-Heung , Bae Jong-Ho , Park Byung-Gook , Lee Jong-Ho
Published: February 2021

Reinforcement learning (RL) using deep Q-networks (DQNs) has shown performance beyond the human level in a number of complex problems. In addition, many studies have focused on bio-inspired hardware-based spiking neural networks (SNNs) given the capabilities of these technologies to realize both parallel operation and low power consumption. Here, we propose an on-chip training method for DQNs applicable to hardware-based SNNs. Because the conventional backpropagation (BP) algorithm is approximated, a performance evaluation based on two simple games shows that the proposed system achieves performance similar to that of a software-based system. The proposed training method can minimize memory usage and reduce power consumption and area occupation levels. In particular, for simple problems, the memory dependency can be significantly reduced given that high performance is achieved without using replay memory. Furthermore, we investigate the effect of the nonlinearity characteristics and two types of variation of non-ideal synaptic devices on the performance outcomes. In this work, thin-film transistor (TFT)-type flash memory cells are used as synaptic devices. A simulation is also conducted using fully connected neural network with non-leaky integrated-and-fire (I&F) neurons. The proposed system shows strong immunity to device variations because an on-chip training scheme is adopted.
Clinical presentation of strokes confined to the insula: a systematic review of literature
Authors: Di Stefano Vincenzo , De Angelis Maria Vittoria , Montemitro Chiara , Russo Mirella , Carrarini Claudia , di Giannantonio Massimo , Brighina Filippo , Onofrj Marco , Werring David J. , Simister Robert
Published: February 2021

Background and purpose

The insular cortex serves a wide variety of functions in humans, ranging from sensory and affective processing to high-level cognition. Hence, insular dysfunction may result in several different presentations. Ischemic strokes limited to the insular territory are rare and deserve a better characterization, to be quickly recognized and to receive appropriate treatment (e.g. thrombolysis).

Methods

We reviewed studies on patients with a first-ever acute stroke restricted to the insula. We searched in the Medline database the keywords “insular stroke” and “insular infarction”, to identify previously published cases. Afterwards, the results were divided depending on the specific insular region affected by the stroke: anterior insular cortex (AIC), posterior insular cortex (PIC) or total insula cortex (TIC). Finally, a review of the clinical correlates associated with each region was performed.

Results

We identified 25 reports including a total of 49 patients (59.7 ± 15.5 years, 48% male) from systematic review of the literature. The most common clinical phenotypes were motor and somatosensory deficits, dysarthria, aphasia and a vestibular-like syndrome. Atypical presentations were also common and included dysphagia, awareness deficits, gustatory disturbances, dysautonomia, neuropsychiatric or auditory disturbances and headache.

Conclusions

The clinical presentation of insular strokes is heterogeneous; however, an insular stroke should be suspected when vestibular-like, somatosensory, speech or language disturbances are combined in the same patient. Further studies are needed to improve our understanding of more atypical presentations.
Correction to: Does plain radiography still have a role in cases of fish bone ingestion in emergency rooms? A retrospective analysis
Authors: Wu Tzu-Chi , Huang Pin-Wen , Tung Chun-Bin
Published: February 2021

A Correction to this paper has been published: 10.1007/s10140-021-01913-6
Heteroclinic connections and Dirichlet problems for a nonlocal functional of oscillation type
Authors: Cesaroni Annalisa , Dipierro Serena , Novaga Matteo , Valdinoci Enrico
Published: February 2021

We consider an energy functional combining the square of the local oscillation of a one-dimensional function with a double-well potential. We establish the existence of minimal heteroclinic solutions connecting the two wells of the potential. This existence result cannot be accomplished by standard methods, due to the lack of compactness properties. In addition, we investigate the main properties of these heteroclinic connections. We show that these minimizers are monotone, and therefore they satisfy a suitable Euler–Lagrange equation. We also prove that, differently from the classical cases arising in ordinary differential equations, in this context the heteroclinic connections are not necessarily smooth, and not even continuous (in fact, they can be piecewise constant). Also, we show that heteroclinics are not necessarily unique up to a translation, which is also in contrast with the classical setting. Furthermore, we investigate the associated Dirichlet problem, studying existence, uniqueness and partial regularity properties, providing explicit solutions in terms of the external data and of the forcing source, and exhibiting an example of discontinuous solution.
Mutants of Lotus japonicus deficient in flavonoid biosynthesis
Authors: Aoki Toshio , Kawaguchi Masayoshi , Imaizumi-Anraku Haruko , Akao Shoichiro , Ayabe Shin-ichi , Akashi Tomoyoshi
Published: February 2021

Spatiotemporal features of anthocyanin accumulation in a model legume Lotus japonicus (Regel) K.Larsen were elucidated to develop criteria for the genetic analysis of flavonoid biosynthesis. Artificial mutants and wild accessions, with lower anthocyanin accumulation in the stem than the standard wild type (B-129 ‘Gifu’), were obtained by ethyl methanesulfonate (EMS) mutagenesis and from a collection of wild-grown variants, respectively. The loci responsible for the green stem of the mutants were named as VIRIDICAULIS (VIC). Genetic and chemical analysis identified two loci, namely, VIC1 and VIC2, required for the production of both anthocyanins and proanthocyanidins (condensed tannins), and two loci, namely, VIC3 and VIC4, required for the steps specific to anthocyanin biosynthesis. A mutation in VIC5 significantly reduced the anthocyanin accumulation. These mutants will serve as a useful system for examining the effects of anthocyanins and proanthocyanidins on the interactions with herbivorous pests, pathogenic microorganisms and nitrogen-fixing symbiotic bacteria, Mesorhizobium loti.
Statistical models to provide meaningful information to GNSS users in the presence of ionospheric scintillation
Authors: Vadakke Veettil S. , Aquino M.
Published: February 2021

Ionospheric scintillation is one of the most challenging problems in Global Navigation Satellite Systems (GNSS) positioning and navigation. Scintillation occurrence can not only lead to an increase in the probability of losing the GNSS signal lock but also reduce the precision of the pseudorange and carrier phase measurements, thus leading to positioning accuracy degradation. Statistical models developed to estimate the probability of loss of lock and Geometric Dilution of Precision normalized 3D positioning errors as a function of scintillation levels are presented. The models were developed following the statistical approach of nonlinear regression on data recorded by Ionospheric Scintillation Monitoring Receivers operational at high and low latitudes. The validation of the probability of loss of lock models indicated average correlation coefficient values above 0.7 and average Root Mean Squared Error (RMSE) values below 0.35. The validation of the positioning error models indicated average RMSE values below 10 cm. The good performance of the developed models indicates that these can provide GNSS users with information on the satellite loss of lock probability and the error in the 3D position under scintillation.
Time–frequency analysis of the Galileo satellite clocks: looking for the J2 relativistic effect and other periodic variations
Authors: Formichella Valerio , Galleani Lorenzo , Signorile Giovanna , Sesia Ilaria
Published: February 2021

When observed from the ground, the frequency of the atomic clocks flying on the satellites of a Global Navigation Satellite System is referred to as apparent frequency, because it is observed through the on-board signal generation chain, the propagation path, the relativistic effects, the measurement system, and the clock estimation algorithm. As a consequence, the apparent clock frequency is affected by periodic variations of different origins such as, for example, the periodic component of the J2 relativistic effect, due to the oblateness of the earth, and the clock estimation errors induced by the orbital estimation errors. We present a detailed characterization of the periodic variations affecting the apparent frequency of the Galileo clocks, obtained by applying time–frequency analysis and other signal processing techniques on space clock data provided by the European Space Agency. In particular, we analyze one year of data from three Galileo Passive Hydrogen Masers, flying on two different orbital planes. Time–frequency analysis reveals how the spectral components of the apparent frequency change with time. For example, it confirms that the amplitude of the periodic signal due to the orbital estimation errors depends on the angle between the sun and the orbital plane. Moreover, it allows to find a more precise estimate of the amplitude of the J2 effect, in agreement with the prediction of the general theory of relativity, and it shows that such amplitude suddenly decreases when the corresponding relativistic correction is applied to the data, thus validating the analytical formula used for the correction.
Priming negatively affects feeding behaviour and aphid biomass of Rhopalosiphum padi on barley
Authors: Wehner Gwendolin , Schikora Adam , Ordon Frank , Will Torsten
Published: February 2021

Plants have developed numerous strategies for responding to abiotic and biotic stresses. In particular, the microbiota surrounding plants may have a positive effect on plant stress responses. One is the reaction to rhizobacteria, which can lead to induced systemic resistance. Gram-negative soil bacteria that produce N-acyl homoserine lactones (AHL), for example, Ensifer meliloti, induce a primed state in plants that is part of the inducible resistance phenomenon. Observing Rhopalosiphum padi feeding behaviour on a priming sensitive barley genotype, treated with the AHL-producing E. meliloti strain expR + ch, using electrical penetration graph technique showed decreased ingestion of food. Aphids appear to overcome this effect within the eight-hour observation period, possibly explaining the absence of differences of reproduction. Reproduction was observed for a period of 14 days on primed and control-treated plants. Long-term observations over a period of 40 days after aphid infestation showed a lower aphid biomass in contrast to a control group, interpreted as delayed population growth, and an increase in the biomass of barley plants. Priming-related genotypic effects of the defence response to aphids were observed, with no beneficial effects on the plant genotype when its sensitivity to priming was low. Previously, an AHL-priming sensitive barley genotype showed enhanced resistance against fungi when primed with the expR + ch strain of E. meliloti. The present study reports the same effect against R. padi. These findings suggest that sensitivity to AHL-priming may represent a new approach for plant breeding, targeting multiple pests in parallel by induced plant resistance.
An efficient ensemble Kalman Filter implementation via shrinkage covariance matrix estimation: exploiting prior knowledge
Authors: Lopez-Restrepo Santiago , Nino-Ruiz Elias D. , Guzman-Reyes Luis G. , Yarce Andres , Quintero O. L. , Pinel Nicolas , Segers Arjo , Heemink A. W.
Published: February 2021

In this paper, we propose an efficient and practical implementation of the ensemble Kalman filter via shrinkage covariance matrix estimation. Our filter implementation combines information brought by an ensemble of model realizations, and that based on our prior knowledge about the dynamical system of interest. We perform the combination of both sources of information via optimal shrinkage factors. The method exploits the rank-deficiency of ensemble covariance matrices to provide an efficient and practical implementation of the analysis step in EnKF based formulations. Localization and inflation aspects are discussed, as well. Experimental tests are performed to assess the accuracy of our proposed filter implementation by employing an Advection Diffusion Model and an Atmospheric General Circulation Model. The experimental results reveal that the use of our proposed filter implementation can mitigate the impact of sampling noise, and even more, it can avoid the impact of spurious correlations during assimilation steps.
Heat Release Rate Characterization of NFPA 1403 Compliant Training Fuels
Authors: Regan John W.
Published: February 2021

When using solid fuels for live fire training,NFPA 1403: Standard on Live Fire Training Evolutionsrequires that the materials be wood based. While the standard offers guidance on the type of fuels that are permissible for use in training, it offers little in the way of quantitative methods of selecting an appropriately sized fuel package. In order to examine the effects of fuel mass and orientation on heat release behavior, free burn heat release rate (HRR) experiments were conducted on twenty-one wood-based training fuel packages and twelve comparison furniture items. Training fuel packages demonstrated peak HRRs ranging from 1.0 MW to 3.6 MW, with the total energy release between 210 MJ and 1615 MJ. The furniture items exhibited peak HRRs between 0.9 MW and 3.7 MW, with the total energy release between 180 MJ and 995 MJ. A least-squares linear regression analysis indicated a good linear fit between total energy release and fuel mass burned among the training fuel packages (R$$^2$$2 $$=$$= 0.98), suggesting that the effective heat of combustion is approximately constant at 14.2 MJ/kg. Generally, peak HRR increased as initial fuel mass increased, although the relationship was more variable, with the peak HRRs of similarly sized training fuel packages varying by nearly 1 MW. The results indicated that while total energy release was dependent largely on the initial fuel mass, peak HRR and peak burning duration were also dependent on the orientation and type of fuel in the fuel package. Wood-based training fuel packages were capable of producing peak HRRs comparable to individual items of furniture, although the total energy release was typically higher for the training fuel packages compared to corresponding furniture items.
Enacting Smart Pedagogy in Higher Education Contexts: Sensemaking through Collaborative Biography
Authors: Reyes Vicente , McLay Katherine , Thomasse Lauren , Olave-Encina Karen , Karimi Arafeh , Rahman Mohammed Tareque , Seneviratne Lalanthi , Tran Tran Le Nghi
Published: February 2021

Scholars and practitioners argue that information and communication technology (ICT) provides flexibility of time and place and softens boundaries between students’ learning lives. The fluid movement between formal and informal learning contexts afforded by digital technology has prompted a re-definition of higher education learning environments to harness its potential. Further, technology can cater to diverse learners and promote lifelong learning in ways that the traditional didactic settings characteristic of tertiary contexts cannot. Scholars and practitioners have labelled this new teaching and learning landscape as smart pedagogy. This article engages with this scholarship by analysing a specific Australian case study in which ICT reforms have been deliberately implemented to adhere to smart pedagogies. Using collective biographies as a methodological tool, this inquiry provides insights into sensemaking experiences of a group of university academics whilst implementing ICT reforms anchored on Smart Pedagogy.
Using Breeding Technologies to Improve Farm Animal Welfare: What is the Ethical Relevance of Telos?
Authors: Kramer K. , Meijboom F. L. B.
Published: February 2021

Some breeding technology applications are claimed to improve animal welfare: this includes potential applications of genomics and genome editing to improve animals’ resistance to environmental stress, to genetically alter features which in current practice are changed invasively (e.g. by dehorning), or to reduce animals’ capacity for suffering. Such applications challenge how breeding technologies are evaluated, which paradigmatically proceeds from a welfare perspective. Whether animal welfare will indeed improve may be unanswerable until proposed applications have been developed and tested sufficiently and until agreement is reached on how to conceptualize animal welfare. Moreover, even if breeding technologies do improve animal welfare, they might be objected to on other ethical grounds. Ethical perspectives on earlier animal biotechnologies are relevant for today’s breeding technologies and their proposed applications, but may need reinterpretation. The current paper applies the concept oftelos, which previously figured mainly in debates on classical genetic engineering, to genomic selection and genome editing aimed at improving animal welfare. It critiques current (Rollin’s and Hauskeller’s) accounts oftelosand offers an alternative conceptualization that applies to recently proposed applications of breeding technologies. This account rejects both removing the desire to pursue characteristic activities and altering animal bodies in ways that compromise their ability to perform such activities, but conditionally allows increasing robustness against environmental stress. Our account oftelosenriches ethical debate on these breeding technology applications by insisting on the connection between the good life, an animal’s constitution, and its activities, thus countering reductive conceptions of welfare.
A Power Control Scheme to Exploit Capture Effect with Fairness Consideration in WLAN
Authors: Su Szu-Lin , Chih Tsung-Hsiu , Tsai Yuan-Chun , Liao Hsieh-Cheng , Wang Yu-Chia
Published: February 2021

In this paper, we develop a physical/medium-access-control cross layer design to improve system throughput with the consideration of fairness for IEEE 802.11 WLAN. From PHY layer perspective, when an access collision occurs, the access point can still decode the corresponding data successfully if the received signal to interference plus noise ratio is larger than the threshold. This phenomenon is referred to as the capture effect. To improve system throughput, this work proposes a Differential Reception-Power Power Control scheme to take advantage of the capture effect. However, the proposed power control scheme cannot provide a fair transmission environment even though it improves the system throughput. To resolve this problem, this work proposes two methods: the adjustment of contention window size and the modification of probability mass function for the selection of the backoff value. The simulation results demonstrate that the proposed schemes can not only remarkably improve system throughput, but also provide a fair transmission environment.
Assessment of the impacts of microbial plant protection products containing Bacillus thuringiensis on the survival of adults and larvae of the honeybee (Apis mellifera)
Authors: Steinigeweg Charlotte , Alkassab Abdulrahim T. , Beims Hannes , Eckert Jakob H. , Richter Dania , Pistorius Jens
Published: February 2021

This study was aimed at evaluating the effect of a microbial pest-controlling product (MPCP) with the active substance Bacillus thuringiensis ssp. aizawai (strain: ABTS-1857) on adults and larvae of honeybees. To determine the contamination levels of Bt spores in different matrices, a colony-feeding study under semi-field conditions was performed. Furthermore, two chronic adult trials and a chronic larval study were conducted under laboratory conditions to test the effects of different concentrations of the plant protection product (PPP) on the development and mortality. Possible modifications of the chronic oral toxicity test were assessed by additional pollen feeding. Our results showed that Bt spores were detected in all matrices over the entire test duration in different concentrations, decreasing over time. The survival of adult bees and larvae was negatively affected in laboratory conditions after a chronic exposure to the MPCP depending on the tested concentrations. Moreover, the earliest sign of bee mortality, resulting from exposure to ABTS-1857, was recorded only after 96 h at the highest tested concentration. Pollen feeding to adults significantly increased the survival of the treated bees. In conclusion, the PPP with the Bt strain ABTS-1857 showed an effect on the mortality of adults and larvae under laboratory conditions. Further studies with Bt-based PPPs under realistic field conditions are necessary to evaluate the potential risk of those MPCPs on honeybees.
Effect of filter extraction solvents on the measurement of the oxidative potential of airborne PM2.5
Authors: Pietrogrande Maria Chiara , Bacco Dimitri , Trentini Arianna , Russo Mara
Published: February 2021

Solvent extraction of PM2.5 samples collected on the filter is a preliminary step for assessing the PM2.5 oxidative potential (OP) using cell-free assays, as the dithiothreitol (DTT) and the ascorbic acid (AA) assays. In this study, we evaluated the effect of the solvent choice by extracting ambient PM2.5 samples with different solvents: methanol, as organic solvent, and two aqueous buffers, i.e., phosphate buffer (PB) and Gamble’s solution (G), as a lung fluid surrogate solution. Both the measured volume-based OPVDTT and OPVAA responses varied for the different extraction methods, since methanol extraction generated the lowest values and phosphate buffer the highest. Although all the tested solvents produced intercorrelated OPVDTT values, the phosphate buffer resulted the most useful for OPDTT assessment, as it provided the most sensible measure (nearly double values) compared with other extractions. The association of the measured OPV values with PM chemical composition suggested that oxidative properties of the investigated PM2.5 samples depend on both transition metals and quinones, as also supported by additional experimental measurements on standard solutions of redox-active species.
Photoelectrocatalysis on TiO2 meshes: different applications in the integrated urban water management
Authors: Collivignarelli Maria Cristina , Abbà Alessandro , Carnevale Miino Marco , Bertanza Giorgio , Sorlini Sabrina , Damiani Silvestro , Arab Hamed , Bestetti Massimiliano , Franz Silvia
Published: February 2021

Recently, among AOPs, photoelectrocatalysis (PEC) on TiO2 is gaining interest. In this study, five different real waters sampled in four different points of the integrated urban water management (IUWM) system were tested with PEC and UV alone, for comparison. This work aims to verify the effect of the PEC suggesting the optimal position in IUWM system where the PEC should be located to obtain the best performance. In groundwaters (GWs), PEC effectively removed atrazine-based compounds (> 99%), trichloroethylene, and perchloroethylene (96%), after 15 min of reaction time. However, given the low concentrations of emerging compounds, the synergistic effect of UV radiation with the catalyst and with the polarization of the mesh was not visible, with very few differences compared with the results obtained with UV alone. Pharmaceutical industrial wastewater (IWW) showed a significant increase in biodegradability after 2 h, both if subjected to PEC or UV (200%), despite the absence of COD removal. The PEC applied on IWW from a sewage sludge treatment plant allowed to effectively remove the COD (39.6%) and increase the biodegradability (300%). Good results in terms of COD removal (33.9%) and biodegradability increase (+900%) were also achieved testing PEC on wastewater treatment plant effluent. Except for GWs, PEC allowed significant EEO savings respect to UV alone (76.2–99.1%).
The environment and politics in science education: the case of teaching fracking
Authors: Dunlop Lynda , Atkinson Lucy , Turkenburg-van Diepen Maria
Published: February 2021

Hydraulic fracturing (‘fracking’), like other complex social and environmental issues, is a controversy about science which raises educational questions about how best to prepare young people to understand, respond to and, where necessary, act (or not) in response. It raises political questions. We present a state-of-the-art review of research literature on fracking and education using systematic strategies, with a view to finding out how it is framed in educational situations and how politics enters the science classroom. This serves as an illustrative case of how contested scientific and technological interventions with implications for the environment and society are treated in school science. The review is supplemented by interviews with 10 teachers of science and engineering working in schools or colleges near sites of operational exploratory fracking. We find that the research literature on teaching hydraulic fracturing is sparse, with only 25 studies relating to teaching and learning about fracking. Few studies (n = 7) relate to high school education. Where it features in science education, fracking is used as a context for interdisciplinarity and critical thinking, and lends itself to approaches using discussion, dialogue and modelling. Outcomes from fracking education range include knowledge gains and critical thinking. Teachers interviewed tended not to see a place for fracking in the curriculum or in the classroom and were averse to including politics in upper high school science education. Our analysis suggests depoliticization through absence of this specific complex environmental issue from the public (education) sphere, reinforced by the desire for ‘balance’ in high school science education and instrumental approaches to science education which prioritize assessed learning outcomes. Dealing with complex social and environmental issues such as hydraulic fracturing in the years of compulsory science schooling is necessary because scientific knowledge is necessary but not sufficient to prepare young people for the critical scientific literacy required to meet sustainable development goals. There is a need to assess and respond to the educational needs of local communities affected by industrial interventions such as fracking. These findings are likely to be relatable to other issues where there are local and global consequences of action or inaction and where the environment and health are pitted against economic and energy demands.