bluuebunny/crossref_metadata_2025 huggingface dataset:
Representations of energy landscapes by sublevelset persistent homology: An example with n-alkanes
Authors: Mirth Joshua , Zhai Yanqin , Bush Johnathan , Alvarado Enrique G. , Jordan Howie , Heim Mark , Krishnamoorthy Bala , Pflaum Markus , Clark Aurora , Z Y , Adams Henry
Published: March 2021

Encoding the complex features of an energy landscape is a challenging task, and often, chemists pursue the most salient features (minima and barriers) along a highly reduced space, i.e., two- or three-dimensions. Even though disconnectivity graphs or merge trees summarize the connectivity of the local minima of an energy landscape via the lowest-barrier pathways, there is much information to be gained by also considering the topology of each connected component at different energy thresholds (or sublevelsets). We propose sublevelset persistent homology as an appropriate tool for this purpose. Our computations on the configuration phase space of n-alkanes from butane to octane allow us to conjecture, and then prove, a complete characterization of the sublevelset persistent homology of the alkane CmH2m+2 Potential Energy Landscapes (PELs), for all m, in all homological dimensions. We further compare both the analytical configurational PELs and sampled data from molecular dynamics simulation using the united and all-atom descriptions of the intramolecular interactions. In turn, this supports the application of distance metrics to quantify sampling fidelity and lays the foundation for future work regarding new metrics that quantify differences between the topological features of high-dimensional energy landscapes.
Low-voltage low-noise gate driven quasi-floating bulk self-cascode current mirror operational transconductance amplifier
Authors: Sharma K. , Sharma R.
Published: March 2021

A gate driven quasi-floating bulk self-cascode current mirror operational transconductance amplifier operable at ±0.9 V supply voltage with DC gain (70 dB), gain bandwidth (250 kHz), noise (2.8 µV/√Hz at 1 Hz), and power consumption (2.96 µW) simulated in 0.18 µm technology has been introduced. Results obtained are superior in comparison to gate driven self-cascode current mirror and regular current mirror OTAs, which can be utilized to improve the performance of analog-mixed signal circuits and systems.
Existence and uniqueness of ground states for attractive Bose–Einstein condensates in box-shaped traps
Authors: Li Yan , Luo Yong
Published: March 2021

We consider ground states of two-dimensional Bose–Einstein condensates in box-shaped trapping potentials Vext(x) with inhomogeneous attractive interactions am(x), which can be described equivalently by minimizers of Gross–Pitaevskii energy functional in bounded domains. In this paper, we prove that there is a threshold a* > 0 such that minimizers exist for 0 < a < a* and the minimizer does not exist for any a > a*. However, if a = a*, it is shown that whether minimizers exist depends sensitively on the asymptotic behaviors of m(x) near its maximum points. Moreover, based on a detailed analysis on the limit behavior of minimizers as a ↗ a*, we prove local uniqueness of minimizers under some suitable assumptions on m(x).
Active position stabilization of an atomic cloud in a narrow-line magneto-optical trap using a Raspberry Pi
Authors: Sillus C. , Franzen T. , Pollklesener B. , Görlitz A.
Published: March 2021

We report on a simple method for an active position stabilization of an atomic cloud trapped in a magneto-optical trap operating on the narrow 182 kHz intercombination line of atomic ytterbium. Our method makes use of the significant sensitivity of the position of a narrow-line magneto-optical trap (MOT) on the laser frequency. After in situ detection of the MOT position using a Pi Camera, an error signal is generated by a Raspberry Pi, which is directly fed back onto the laser frequency. Thus, perturbations of the MOT position, e.g., due to drifts of the Zerodur cavity to which the MOT laser is stabilized or the ambient magnetic field, can be compensated directly. Our method allows for long-term stabilization of the MOT position on a 10 µm scale and thus improves loading of a tightly focused optical trap.
Double-D2Q9 lattice Boltzmann models with extended equilibrium for two-dimensional magnetohydrodynamic flows
Authors: De Rosis Alessandro , Al-Adham Joanne , Al-Ali Hamda , Meng Ran
Published: March 2021

The vast majority of the existing lattice Boltzmann methods (LBMs) suggest to relax relevant quantities to a second-order truncated equilibrium state. Despite its simplicity and popularity, this choice does not fully exploit the potential of any lattice discretization. In this paper, an extended equilibrium state is adopted to evaluate the suitability of different LBMs (i.e., the Bhatnagar–Gross–Krook, the multiple-relaxation-time in terms of raw and central moments, and the simplified one) to simulate two-dimensional magnetohydrodynamic flows by means of the D2Q9 velocity space. Two sets of particle distribution functions are employed: one for the flow field and the other for the magnetic one. Even if the minimal five-velocities discretization is sufficient to represent the evolution of the latter, a nine-velocities model enhances the capability to enforce the divergence-free condition of the magnetic field, as shown. Therefore, a double-D2Q9 approach is herein devised. Eventually, the computational cost involved by all the schemes is discussed both in terms of virtual memory and run time. Interestingly, the simplified LBM for magnetohydrodynamic flows is herein presented for the first time.
On the Gibbs–Thomson equation for the crystallization of confined fluids
Authors: Scalfi Laura , Coasne Benoît , Rotenberg Benjamin
Published: March 2021

The Gibbs–Thomson (GT) equation describes the shift of the crystallization temperature for a confined fluid with respect to the bulk as a function of pore size. While this century old relation is successfully used to analyze experiments, its derivations found in the literature often rely on nucleation theory arguments (i.e., kinetics instead of thermodynamics) or fail to state their assumptions, therefore leading to similar but different expressions. Here, we revisit the derivation of the GT equation to clarify the system definition, corresponding thermodynamic ensemble, and assumptions made along the way. We also discuss the role of the thermodynamic conditions in the external reservoir on the final result. We then turn to numerical simulations of a model system to compute independently the various terms entering in the GT equation and compare the predictions of the latter with the melting temperatures determined under confinement by means of hyper-parallel tempering grand canonical Monte Carlo simulations. We highlight some difficulties related to the sampling of crystallization under confinement in simulations. Overall, despite its limitations, the GT equation may provide an interesting alternative route to predict the melting temperature in large pores using molecular simulations to evaluate the relevant quantities entering in this equation. This approach could, for example, be used to investigate the nanoscale capillary freezing of ionic liquids recently observed experimentally between the tip of an atomic force microscope and a substrate.
Interpreting dynamics of snap-off in a constricted capillary from the energy dissipation principle
Authors: Zhang Chunwei , Yuan Zhengyi , Matsushita Shintaro , Xiao Feng , Suekane Tetsuya
Published: March 2021

Snap-off usually occurs during two-phase fluid displacement in a constricted capillary, where the nonwetting phase fluid is cut into blobs or ganglia due to surface tension. Snap-off has been intensely recognized as a predominant pore-scale mechanism that may be responsible for the breakup and trapping of the nonwetting phase in complex geophysical structures. Herein, we investigated the dynamics of snap-off in a constricted pore and throat structure with a square cross-section using the volume of fluid method. Despite the geometric constraint dictated by Roof, a new judging diagram for the occurrence of snap-off was proposed as a function of Ca number and viscosity ratio. Our prediction from the numerical simulation is consistent with the analytical solution derived from the balance of capillary and hydrodynamic pressure. Furthermore, the associated transient energy balance was thoroughly studied, considering the alteration of the surface energy, kinetic energy, total input energy, and viscous dissipation during the period of snap-off. The results indicated that snap-off is always characterized by a sharp decline in the surface energy, which resulted in a surge in the kinetic energy and viscous dissipation. In addition, we observed a sharp surge in the viscous dissipation rate curve associated with such energy change, which is attributed to the redistribution of the velocity field. The sudden surge unanimously decreased while increasing the Ca number or viscosity ratio. Meanwhile, the position at which snap-off took place was shifted downstream of the throat, explaining the condition of the snap-off had become much more difficult.
Physiological implications of COVID-19 in reproduction: angiotensin-converting enzyme 2 a key player
Authors: Sharma G. Taru , Chandra Vikash , Mankuzhy Pratheesh , Thirupathi Yasotha , Swain Dilip Kumar , Pillai Harikrishna , Patel Shailesh Kumar , Pathak Mamta , Guttula SaiKumar
Published: March 2021

The COVID-19 outbreak, caused by severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), was first identified in China, and it has quickly become a global threat to public health due to its rapid rate of transmission and fatalities. Angiotensin-converting enzyme 2 (ACE2) has been identified as a receptor that mediates the entry of SARS-CoV-2 into human cells, as in the case of severe acute respiratory syndrome coronavirus (SARS-CoV). Several studies have reported that ACE2 expression is higher in Leydig, Sertoli and seminiferous ductal cells of males, as well as in ovarian follicle cells of females, suggesting possible potential pathogenicity of the coronavirus in the reproductive system. Higher ACE2 expression in the human placenta and reports of vertical transmission of SARS-CoV-2 among clinical cases have increased the relevance of further studies in this area. This review focuses on the interaction between SARS-CoV-2 and the ACE2 receptor and speculates on the mechanistic interplay in association with male and female reproductive physiology. In addition, based on the available literature, we discuss the alleged sex differences in terms of the infectivity of SARS-CoV-2, which is claimed greater among males, and further explore the physiological role of ACE2 and 17β-oestradiol for the same.
The assemblage of birds struck by aircraft differs among nearby airports in the same bioregion
Authors: Steele William K. , Weston Michael A.
Published: March 2021

Abstract Context Bird–aircraft collisions impose an economic cost and safety risk, yet ecological studies that inform bird hazard management are few, and to date no study has formally compared species’ strike profiles across airports. In response to strike risks, airports have implemented customised management on an airport-by-airport basis, based on the assumption that strike risk stems from prevailing local circumstances. We tested this assumption by comparing a decade of wildlife–aircraft strikes at three airports situated in the same bioregion (likely to have similar fauna) of Victoria, Australia. Aim To compare the assemblage of wildlife struck by aircraft at three major airports in the same bioregion. Method Standardised wildlife strike data were analysed from three airports (Avalon, Melbourne and Essendon Airports), in the Victorian Volcanic Plains bioregion, central Victoria, Australia. Ten discrete 1-year sampling periods from each airport were compared, spanning the period 2009–19. Bird data were comparable, and data on mammals were considered less reliable, so emphasis was placed on birds in the present study. Results In total, 580 bird strikes were analysed, with the most commonly struck species being Australian magpie (Cracticus tibicen; 16.7%), Eurasian skylark (Alauda arvensis; 12.2%), Australian pipit (Anthus australis; 12.1%), masked lapwing (Vanellus miles; 5.9%), nankeen kestrel (Falco cenchroides; 5.0%), house sparrow (Passer domesticus; 4.8%), welcome swallow (Hirundo neoxena; 4.3%) and tree martin (Petrochelidon nigricans; 4.0%). The assemblage of birds struck by aircraft over the decade of study differed between airports. The most commonly struck species drove the assemblage differences between airports. Conclusions and implications In the present study system, airports experienced discrete strike risk profiles, even though they are in the same bioregion. The airports examined differed in terms of air traffic movement rates, aircraft types, landscape context and bird hazard management effort. Given that strike risks profiles differ among airports, customised management at each airport, as is currently the case, is supported.
Vagus nerve stimulation activates two distinct neuroimmune circuits converging in the spleen to protect mice from kidney injury
Authors: Tanaka Shinji , Abe Chikara , Abbott Stephen B. G. , Zheng Shuqiu , Yamaoka Yusuke , Lipsey Jonathan E. , Skrypnyk Nataliya I. , Yao Junlan , Inoue Tsuyoshi , Nash William T. , Stornetta Daniel S. , Rosin Diane L. , Stornetta Ruth L. , Guyenet Patrice G. , Okusa Mark D.
Published: March 2021

Significance

The ability of vagus nerve stimulation to generate anti-inflammatory and tissue-protective effects has been known for some time. We have made use of cutting-edge tools to precisely map the neural circuits that contribute to beneficial effects of vagus nerve stimulation. Stimulation was specifically restricted to either the afferent or efferent neurons in the vagus nerve by genetically programming the appropriate cells to express a light-sensitive cation channel. We show that, while both afferent and efferent signals provide protection from kidney injury, afferent stimulation generates a sympathetic response that protects mice in the absence of efferent vagus signals. This provides an insight into the pathways of neuroimmune protection and potential therapeutics.
The effective graph reveals redundancy, canalization, and control pathways in biochemical regulation and signaling
Authors: Gates Alexander J. , Brattig Correia Rion , Wang Xuan , Rocha Luis M.
Published: March 2021

Significance

Many biological networks are modeled with multivariate discrete dynamical systems. Current theory suggests that the network of interactions captures salient features of system dynamics, but it misses a key aspect of these networks: some interactions are more important than others due to dynamical redundancy and nonlinearity. This unequivalence leads to a canalized dynamics that differs from constraints inferred from network structure alone. To capture the redundancy present in biochemical regulatory and signaling interactions, we present the effective graph, an experimentally validated mathematical framework that synthesizes both structure and dynamics in a weighted graph representation of discrete multivariate systems. Our results demonstrate the ubiquity of redundancy in biology and provide a tool to increase causal explainability and control of biochemical systems.
Cytonemes with complex geometries and composition extend into invaginations of target cells
Authors: Wood Brent M. , Baena Valentina , Huang Hai , Jorgens Danielle M. , Terasaki Mark , Kornberg Thomas B.
Published: March 2021

Cytonemes are specialized filopodia that mediate paracrine signaling in Drosophila and other animals. Studies using fluorescence confocal microscopy (CM) established their general paths, cell targets, and essential roles in signaling. To investigate details unresolvable by CM, we used high-pressure freezing and EM to visualize cytoneme structures, paths, contents, and contacts. We observed cytonemes previously seen by CM in the Drosophila wing imaginal disc system, including disc, tracheal air sac primordium (ASP), and myoblast cytonemes, and identified cytonemes extending into invaginations of target cells, and cytonemes connecting ASP cells and connecting myoblasts. Diameters of cytoneme shafts vary between repeating wide (206 ± 51.8 nm) and thin (55.9 ± 16.2 nm) segments. Actin, ribosomes, and membranous compartments are present throughout; rough ER and mitochondria are in wider proximal sections. These results reveal novel structural features of filopodia and provide a basis for understanding cytoneme cell biology and function.
A simple and low cost USB webcam-driven optical tomography system suitable for teaching x-ray computed tomography
Authors: Vega Mernes Cristhian Ariel , Francelino Isabella Grinberg , Kakuno Edson Massayuki , Hönnicke Marcelo Goncalves
Published: March 2021

A simple and cheap optical analog computed tomography (CT) system, useful for teaching x-ray CT for physics, medical physics and engineering physics students without applying ionizing radiation is presented. White spectrum of a light emitting diode (LED) source was characterized by using an in-house constructed spectrophotometer. A simple electronic hardware, utilizing a synchronization of an universal serial bus webcam and direct current (DC) motor was developed in such a way that, a single click on the record video button of the webcam software is enough to run the tomograph. Finally, the two- and three-dimensional tomography reconstructions are briefly discussed and presented.
Surface activation of poly(methyl methacrylate) for microfluidic device bonding through a H2O plasma treatment linked with a low-temperature annealing
Authors: Immanuel Philip Nathaniel , Chiang Chao-Ching , Yang Chung-Rong , Subramani Murugan , Lee Tien-Hsi , Huang Song-Jeng
Published: March 2021

This paper reports on a rapid, lossless process for the bonding of poly(methyl methacrylate) (PMMA) substrates for use in microfluidic devices for blood tests, utilizing H2O plasma, and H2O linked rapid thermal annealing (RTA) treatments. The bonding of PMMA produced with H2O plasma linked with RTA was analyzed, and its effect on the bonding of free radicals was investigated. The PMMA surface treatment was performed at constant RF power and H2O vapor flow but changing plasma treatment times in both processes. The surface modification of the PMMA subjected to the H2O plasma treatment was studied by optical emission spectroscopy, which confirmed that the relative intensity of hydroxyl radicals and oxygen emission peaks. The surface of the PMMA after being subjected to the plasma linked with RTA treatment was also characterized. The free energy increased with the plasma treatment time. The tensile test results revealed that the strength of OH bonds on the PMMA surface increased with a high plasma treatment time of 120 s. After bonding, UV–visible transmission spectrum measurements revealed that the transparency of the microfluidic device increased. We demonstrated the bonding of a microfluidic device with plasma treatment without deformation. This method provides an ideal bonding technique for the manufacture of microfluidic devices with PMMA. This technique has more advantages than other bonding techniques.
The different behaviors of thermal noise in collective quantum steering and genuinely tripartite steering induced by atomic coherence
Authors: Li Lingchao
Published: March 2021

Multipartite quantum steering has important application in quantum information processing. Here we study the influence of thermal noise on the collective quantum steering and genuine tripartite steering in a system of four-level inverted Y-type atoms, in which the atomic coherence is initially prepared and the cavity is coupled to a thermal reservoir. It is found that for the cases of the balanced and unbalanced cavity losses, the thermal noise plays a positive role in realizing the collective steering. However the case is different for the genuine tripartite steering effect. For the case of either balanced or unbalanced cavity losses, the thermal noise would destroy genuine tripartite steering effect and reduce the parameter region of genuine tripartite steering. The thermal noise plays a negative role in realizing genuine tripartite steering. Specially, it is verified that the genuine tripartite steering does not reject the bipartite steering, which is very different from the collective quantum steering requiring no bipartite steering. The present scheme may provide some help for potential applications such as quantum communication.
Observation of frequency band-switchable topological edge modes using a 2 bit coding acoustic topological insulator
Authors: Song Xin-Pei , Chen Tian-Ning , Chen Chen , Ding Wei
Published: March 2021

Here, the frequency band-switchable topologically protected edge state transport is realized in simulation and experiment based on a 2 bit coding acoustic topological insulator that consists of two layers of sonic crystals arrayed by the Helmholtz resonant triangle-lattice scatters with two distinct rotation angles. The acoustic topological phase transition is revealed and the gapless frequency bands are predicted. Experimentally measured transmission spectra and simulated pressure fields show good agreement with the predicted results. The error between the measured and the predicted results is illustrated by introducing a slit into the nested scatters, which is comparable to the manufacturing accuracy of the commercial 3D printer. Our work provides a simple method of coding to achieve the frequency-switchable acoustic topological edge modes, and paves a promising way to design the intelligent, programmable, and flexible acoustic devices.
CO oxidation over defective and nonmetal doped MoS2 monolayers
Authors: Linghu Yaoyao , Lu Dongmei , Wu Chao
Published: March 2021

Defective (missing S atoms) and nonmetal (C- and N-) doped MoS2 monolayers in the 2H and 1T′ phases have been evaluated for catalyzing CO oxidation based on first-principles calculations. For the reaction 2CO + O2 → 2CO2, the oxidization of the first CO molecule is fairly easy and sometimes is even spontaneous, as the O2 molecule is highly activated or dissociates upon adsorption. However, for the defective (2H-), C-doped (1T′-), and N-doped (2H- and 1T′-) MoS2 monolayers, the remaining O* adatom often refuses to react with other CO molecules and is hard to be removed (barrier > 1.20 eV). Only when over the C-doped 2H- and defective 1T′-MoS2 monolayers, the removal of the second O* adatom requires to overcome moderate barriers (0.74 and 0.88 eV, respectively) by reacting with another CO molecule via the Eley–Rideal mechanism and the catalysts are recovered. The barriers can be further reduced by applying either tensile or compressive strain to the MoS2 nanosheet. In contrast, the Langmuir–Hinshelwood mechanism is followed over the metal-containing MoS2 nanosheets, as the bigger size of metal dopants allow the co-adsorption of CO and O2. Therefore, the C-doped 2H- and defective 1T′-MoS2 monolayers are promising nonmetal-doped catalysts for CO oxidation.
Carbon nitride grafted waste-derived carbon as sustainable materials for lithium–sulfur batteries
Authors: Jia Yongfeng , Ji Lei , Gao Hongda , Liu Yanji , Yang Daotong , Li Tunan , Bai Jie , Hu Quanli , Wang Meijun , Liu Jinghai
Published: March 2021

The synthesis of a sustainable material through carbon nitride (C3N4) chemically grafted on waste-derived carbon including carbonizing coals (PM), melamine-urea-formaldehyde resins (MUF-C-1100), and luffa cylindrical sponges (SG), respectively, and its application as sulfur cathode in lithium-sulfur (Li-S) batteries were demonstrated. The Li-S cell assembled by the sulfur (S) cathode with component from C3N4 grafted coal-derived carbon (PM-CN) possesses a specific capacity of 1269.8 mA h g−1 at 0.05 C. At 1 C, the initial specific capacity of PM cathode is only 380.0 mA h g−1, comparable to the PM-CN5 cathode of 681.9 mA h g−1, and PM-CN10 cathode of 580.7 mA h g−1, respectively. And, PM-CN 5 cathode presents the capacity retention of 75.9% with a coulomb efficiency (C.E.) of 97.3% after 200 cycles. The MUF-CN cathode gives a specific capacity of 1335.6 mA h g−1 at 0.05 C, and the capacity retention of 66.7% with a C. E. of 93.6% after 300 cycles at 0.5 C. The SG-CN cathode had a specific capacity of 953.9 mA h g−1 at 0.05 C, and capacity retention of 95.1% with a C. E. of 98.2% after 125 cycles at 1 C. The remarkable improved performances were mainly ascribed to the sustainable materials as S host with micro-meso pore and C3N4 structure providing the strong affinity N sites to lithium polysulfides (LiPSs). This work provides an attractive approach for the preparation of sustainable materials by rational design of grafting C3N4 to waste-derived carbons with functions as S cathode materials for high-performance Li-S batteries.
Proton path reconstruction for proton computed tomography using neural networks
Authors: Ackernley T , Casse G , Cristoforetti M
Published: March 2021

The most likely path formalism (MLP) is widely established as the most statistically precise method for proton path reconstruction in proton computed tomography. However, while this method accounts for small-angle multiple coulomb scattering (MCS) and energy loss, inelastic nuclear interactions play an influential role in a significant number of proton paths. By applying cuts based on energy and direction, tracks influenced by nuclear interactions are largely discarded from the MLP analysis. In this work we propose a new method to estimate the proton paths based on a deep neural network (DNN). Through this approach, estimates of proton paths equivalent to MLP predictions have been achieved in the case where only MCS occurs, together with an increased accuracy when nuclear interactions are present. Moreover, our tests indicate that the DNN algorithm can be considerably faster than the MLP algorithm.
Atlas construction and spatial normalisation to facilitate radiation-induced late effects research in childhood cancer
Authors: Veiga Catarina , Lim Pei , Anaya Virginia Marin , Chandy Edward , Ahmad Reem , D’Souza Derek , Gaze Mark , Moinuddin Syed , Gains Jennifer
Published: March 2021

Reducing radiation-induced side effects is one of the most important challenges in paediatric cancer treatment. Recently, there has been growing interest in using spatial normalisation to enable voxel-based analysis of radiation-induced toxicities in a variety of patient groups. The need to consider three-dimensional distribution of doses, rather than dose-volume histograms, is desirable but not yet explored in paediatric populations. In this paper, we investigate the feasibility of atlas construction and spatial normalisation in paediatric radiotherapy. We used planning computed tomography (CT) scans from twenty paediatric patients historically treated with craniospinal irradiation to generate a template CT that is suitable for spatial normalisation. This childhood cancer population representative template was constructed using groupwise image registration. An independent set of 53 subjects from a variety of childhood malignancies was then used to assess the quality of the propagation of new subjects to this common reference space using deformable image registration (i.e. spatial normalisation). The method was evaluated in terms of overall image similarity metrics, contour similarity and preservation of dose-volume properties. After spatial normalisation, we report a dice similarity coefficient of 0.95 ± 0.05, 0.85 ± 0.04, 0.96 ± 0.01, 0.91 ± 0.03, 0.83 ± 0.06 and 0.65 ± 0.16 for brain and spinal canal, ocular globes, lungs, liver, kidneys and bladder. We then demonstrated the potential advantages of an atlas-based approach to study the risk of second malignant neoplasms after radiotherapy. Our findings indicate satisfactory mapping between a heterogeneous group of patients and the template CT. The poorest performance was for organs in the abdominal and pelvic region, likely due to respiratory and physiological motion and to the highly deformable nature of abdominal organs. More specialised algorithms should be explored in the future to improve mapping in these regions. This study is the first step toward voxel-based analysis in radiation-induced toxicities following paediatric radiotherapy.
Oxygen enhancement ratios of cancer cells after exposure to intensity modulated x-ray fields: DNA damage and cell survival
Authors: Matsuya Yusuke , McMahon Stephen J , Butterworth Karl T , Naijo Shingo , Nara Isshi , Yachi Yoshie , Saga Ryo , Ishikawa Masayori , Sato Tatsuhiko , Date Hiroyuki , Prise Kevin M
Published: March 2021

Hypoxic cancer cells within solid tumours show radio-resistance, leading to malignant progression in fractionated radiotherapy. When prescribing dose to tumours under heterogeneous oxygen pressure with intensity-modulated radiation fields, intercellular signalling could have an impact on radiosensitivity between in-field and out-of-field (OF) cells. However, the impact of hypoxia on radio-sensitivity under modulated radiation intensity remains to be fully clarified. Here, we investigate the impact of hypoxia on in-field and OF radio-sensitivities using two types of cancer cells, DU145 and H1299. Using a nBIONIX hypoxic culture kit and a shielding technique to irradiate 50% of a cell culture flask, oxygen enhancement ratios for double-strand breaks (DSB) and cell death endpoints were determined. These in vitro measurements indicate that hypoxia impacts OF cells, although the hypoxic impacts on OF cells for cell survival were dose-dependent and smaller compared to those for in-field and uniformly irradiated cells. These decreased radio-sensitivities of OF cells were shown as a consistent tendency for both DSB and cell death endpoints, suggesting that radiation-induced intercellular communication is of importance in advanced radiotherapy dose-distributions such as with intensity-modulated radiotherapy.
Classification of chronic venous diseases based on skin temperature patterns
Authors: Dahlmanns Stephan , Reich-Schupke Stefanie , Schollemann Franziska , Stücker Markus , Leonhardt Steffen , Teichmann Daniel
Published: March 2021

Objective. Infrared thermography has the potential to complement the classification of chronic venous diseases (CVD), but lacks sophisticated insights on the association between recorded skin temperatures and the severity of CVD. This research aims to identify temperature patterns in the lower legs of patients that are distinct in specific forms of CVD, including florid ulcers. Approach. Infrared images were acquired in a clinical trial with 36 patients and segmented using a region selection algorithm. The regions were analyzed with respect to seven predefined features. The most prominent thermal features were translated into rules to classify CVD. Main results. Patients with mild forms of CVD show local increases in skin temperature by more than 1.5 °C. These regions were 2.0 °C warmer when CVD is more severe. Temperature variations of on average 0.4 °C occurred within venous leg ulcers. Furthermore, these wounds were 1.1 °C–6.3 °C colder than periwound skin. Significance. Temperature patterns characterized by differences in temperature that occur within a few centimeters or millimeters are distinct to specific stages of CVD. These patterns are present in the locations of varicose veins and tissue damages. Significance. The findings increase the body of knowledge on the potential for the early detection of CVD using infrared thermography. Applying the presented algorithms and rules, infrared thermography may become a complementary tool for the objective classification of CVD.
The effects of AlGaN quantum barriers on carrier flow in deep ultraviolet nanowire laser diode
Authors: Sharif Muhammad Nawaz , Niass Mussaab Ibrahiam , Liou Juin J , Wang Fang , Liu Yuhuai
Published: March 2021

Aluminium (Al) composition is a critical parameter of performance for deep ultraviolet (DUV) AlGaN devices. In multiple-quantum-wells (MQW) nanowire laser diode, quantum barriers play an important role in carriers’ flow (electrons, holes). In this work, the impact of composition, and the thickness of AlGaN-based quantum barriers is being studied. The study suggests that by properly increasing Al composition of

A

l

x

G

a

1
−
x

N

quantum barriers, the height of the conduction band barrier decreases, which enhances electron leakage from MQW, while increasing the height of the valance band barrier, which, in turn, suppresses hole injection efficiency toward MQW. Such variations in band height greatly affect opto-electronic characteristics and performance of AlGaN nanowire. Furthermore, the study also suggests that quantum barrier thickness has much influence on DUV nanowire performance. The decrease in thickness of quantum barriers has little effect on confinement of the optical field, but significant effect on optical emitted power. It is found that by decreasing the thickness of quantum barriers, optical emitted power along with stimulated recombination rate is reduced. Contrastingly, as the thickness of quantum barriers increases, hole injection efficiency gets enhanced while electron leakage from MQW gets reduced. The above observations suggest that the higher the thickness of quantum barriers, the better the carriers’ flow toward MQW and hence, the performance is improved.
On the triad transfer analysis of plasma turbulence: symmetrization, coarse graining, and directional representation
Authors: Maeyama S , Sasaki M , Fujii K , Kobayashi T , Dendy R O , Kawachi Y , Arakawa H , Inagaki S
Published: March 2021

This article discusses triad transfer analysis via quadratic nonlinearity. To avoid fictitious interactions, symmetrization of the triad transfer is reviewed, including arbitrary orthogonal decomposition and coarse graining. The directional representation of the symmetrized triad transfer is proposed by minimizing the number of edges in a network graph of triad interactions with keeping the energy consistency. The directional representation simplifies visualization and allows us to reduce the energy transfer into a one-to-one relation, while eliminating fictitious interactions in non-symmetrized triad transfer functions. Energy transfer processes among plasma turbulent fluctuations that decompose by the singular value decomposition are analyzed as an application. A network graph visualization clearly demonstrates the importance of symmetrization and the consistency between the symmetrized triad transfer and its directional representation.
Appearance of objectivity for NV centers interacting with dynamically polarized nuclear environment
Authors: Kwiatkowski Damian , Cywiński Łukasz , Korbicz Jarosław K.
Published: March 2021

Quantum-to-classical transition still eludes a full understanding. Out of its multiple aspects, one has recently gained an increased attention—the appearance of objective world out of the quantum. One particular idea is that objectivity appears thanks to specific quantum state structures formation during the evolution, known as spectrum broadcast structures (SBS). Despite that quite some research was already performed on this strong and fundamental form of objectivity, the practical realization of SBS in a concrete physical medium has not been explicitly analyzed so far. In this work, we study the possibility to simulate objectivization process via SBS formation using widely studied nitrogen-vacancy centers in diamonds. Assuming achievable limits of dynamical polarization technique, we show that for high, but experimentally viable polarizations (p > 0.5) of nuclear spins and for magnetic fields lower than ≈20 G the state of the NV center and its nearest polarized environment approaches an SBS state reasonably well.
A polarization-insensitive dual-band plasmonic metamaterial absorber for a sensor application
Authors: Kang Yongqiang , Gao Peng , Liu Hongmei , Gao Lishuo
Published: March 2021

A polarization-insensitive dual-band plasmonic metamaterial absorber is proposed, which is constituted by merely the metal nano-cylinder and a continuous metallic ground separated by a middle dielectric layer. Two resonance peaks with over 97% absorbance derived from ‘the fundamental resonance and the surface lattice resonance are realized. The effective medium approach and the transmission line modeling show good agreement with results from numerical simulation. In addition, we demonstrated that proposed dual-absorber retain nearly perfect absorbance for all polarization angles of both TE and TM modes on normal incidence. It is different from previous work that the dual-frequency response is obtained by combining two subunits of different sizes. Importantly, the second absorption peak result from surface lattice resonance with narrow line-width has large sensitivity perform and high quality factor, which has significant potential in the application of biosensors and monitoring.
ACROPOLIS: A generiC fRamework fOr Photodisintegration Of LIght elementS
Authors: Depta Paul Frederik , Hufnagel Marco , Schmidt-Hoberg Kai
Published: March 2021

The remarkable agreement between observations of the
primordial light element abundances and the corresponding
theoretical predictions within the standard cosmological history
provides a powerful method to constrain physics beyond the standard
model of particle physics (BSM). For a given BSM model these
primordial element abundances are generally determined by (i)
Big Bang Nucleosynthesis and (ii) possible subsequent
disintegration processes. The latter potentially change the
abundances due to late-time high-energy injections which may be
present in these scenarios. While there are a number of public codes
for the first part, no such code is currently available for the
second. Here we close this gap and present ACROPOLIS,
A generiC fRamework fOr
Photodisintegration Of LIght
elementS. The widely discussed cases of decays as well as
annihilations can be run without prior coding knowledge within
example programs. Furthermore, due to its modular structure,
can easily be extended also to other
scenarios.

For the most recent version of this manual, please visit the GitHub repository at
https://github.com/skumblex/acropolis.
Resonant effects in the spontaneous bremsstrahlung process of ultrarelativistic electrons in the fields of a nucleus and a pulsed light wave
Authors: Roshchupkin Sergei P , Dubov Alexander , Dubov Victor V
Published: March 2021

This article focuses on the resonant high-energy spontaneous bremsstrahlung of ultrarelativistic electrons with considerable energies

E
i

≳

10

2

GeV in the field of a nucleus and a quasimonochromatic laser wave with an intensity

I
≲

10

16

÷ 1017 W cm−2. Under resonant conditions within the light field the intermediate virtual electron transformed into a real particle. Therefore, the initial second order process in accordance with the fine structure constant in the laser field effectively reduced to two successive processes of the first order: the laser-stimulated Compton-effect and laser field-assisted scattering of an electron by a nucleus. In this work we derive the expressions for the resonant differential cross-sections of this processes using the simultaneous registration of the frequency and outgoing angle of the spontaneous photon and the absorption of the rth wave of photons (where r = 1,2,3,...is the resonance number). To summarize, for the first resonance of channel A, the resonant differential cross-section attains a magnitude of the ∼1012 and the third resonance of channel B attains ∼105 in units of

α

Z
2

r
e
2

(
c

m
2

)

. Finally, scientific laser pulse radiation (SLAC, FAIR, XFEL, ELI, XCELS) can be used to verify the model calculations.
Informational properties of holographic Lifshitz field theory *
Authors: Gong Huajie , Liu Peng , Fu Guoyang , Kuang Xiao-Mei , Wu Jian-Pin
Published: March 2021

In this paper, we explore the properties of holographic entanglement entropy (HEE), mutual information (MI) and entanglement of purification (EoP) in holographic Lifshitz theory. These informational quantities exhibit some universal properties of holographic dual field theory. For most configuration parameters and temperatures, these informational quantities change monotonically with the Lifshitz dynamical critical exponent z. However, we also observe some non-monotonic behaviors for these informational quantities in some specific spaces of configuration parameters and temperatures. A particularly interesting phenomenon is that a dome-shaped diagram emerges in the behavior of MI vs z, and correspondingly a trapezoid-shaped profile appears in that of EoP vs z. This means that for some specific configuration parameters and temperatures, the system measured in terms of MI and EoP is entangled only in a certain intermediate range of z.
Severity of drought and heatwave crop losses tripled over the last five decades in Europe
Authors: Brás Teresa Armada , Seixas Júlia , Carvalhais Nuno , Jägermeyr Jonas
Published: March 2021

Extreme weather disasters (EWDs) can jeopardize domestic food supply and disrupt commodity markets. However, historical impacts on European crop production associated with droughts, heatwaves, floods, and cold waves are not well understood—especially in view of potential adverse trends in the severity of impacts due to climate change. Here, we combine observational agricultural data (FAOSTAT) with an extreme weather disaster database (EM-DAT) between 1961 and 2018 to evaluate European crop production responses to EWD. Using a compositing approach (superposed epoch analysis), we show that historical droughts and heatwaves reduced European cereal yields on average by 9% and 7.3%, respectively, associated with a wide range of responses (inter-quartile range +2% to −23%; +2% to −17%). Non-cereal yields declined by 3.8% and 3.1% during the same set of events. Cold waves led to cereal and non-cereal yield declines by 1.3% and 2.6%, while flood impacts were marginal and not statistically significant. Production losses are largely driven by yield declines, with no significant changes in harvested area. While all four event frequencies significantly increased over time, the severity of heatwave and drought impacts on crop production roughly tripled over the last 50 years, from −2.2% (1964–1990) to −7.3% (1991–2015). Drought-related cereal production losses are shown to intensify by more than 3% yr−1. Both the trend in frequency and severity can possibly be explained by changes in the vulnerability of the exposed system and underlying climate change impacts.
Virtual reality and augmented reality displays: advances and future perspectives
Authors: Yin Kun , He Ziqian , Xiong Jianghao , Zou Junyu , Li Kun , Wu Shin-Tson
Published: March 2021

Virtual reality (VR) and augmented reality (AR) are revolutionizing the ways we perceive and interact with various types of digital information. These near-eye displays have attracted significant attention and efforts due to their ability to reconstruct the interactions between computer-generated images and the real world. With rapid advances in optical elements, display technologies, and digital processing, some VR and AR products are emerging. In this review paper, we start with a brief development history and then define the system requirements based on visual and wearable comfort. Afterward, various VR and AR display architectures are analyzed and evaluated case by case, including some of the latest research progress and future perspectives.
REAP: revealing drug tolerant persister cells in cancer using contrast enhanced optical coherence and photoacoustic tomography
Authors: Liu Mengyang , Deloria Abigail J , Haindl Richard , Li Qian , Szakacs Gergely , Csiszar Agnes , Schrittwieser Stefan , Muellner Paul , Hainberger Rainer , Pelaz Beatriz , Polo Ester , Del Pino Pablo , Penttinen Antti , Guina Mircea , Niemi Tapio , Meiburger Kristen , Molinari Filippo , Menhard Christian , Heidelin Judith , Andresen Volker , Geuzebroek Douwe , Drexler Wolfgang
Published: March 2021

Despite chemotherapy, residual tumors often rely on so-called drug tolerant persister (DTP) cells, which evade treatment to give rise to therapy-resistant relapse and refractory disease. Detection of residual tumor cells proves to be challenging because of the rarity and heterogeneity of DTP cells. In the framework of a H2020 project, REAP will gather researchers and engineers from six countries, who will combine their expertise in biology, chemistry, oncology, material sciences, photonics, and electrical and biomedical engineering in the hope of revealing DTPs in cancer using contrast enhanced multimodal optical imaging. Laser sources for photoacoustic microscopy, photoacoustic tomography, and optical coherence tomography will be developed to enable the design of a two-photon laser scanning optical coherence photoacoustic microscopy system and an optical coherence photoacoustic tomography system. Furthermore, novel photoacoustic detectors using micro-ring resonator will be designed and fabricated, granting improved sensitivity and easier integration of multiple optical imaging modalities into a single system. Innovative algorithms will be developed to reconstruct and analyze the images quickly and automatically. With successful implementation of this four-year project, we can not only gain insight into the mechanisms governing DTPs, but also significantly advance the technology readiness level of contrast agents, lasers, sensors, and image analysis software through joint efforts.
COVID-19 Experiences, PPE, and Health Concerns in Toronto, Canada Bicycle Delivery Workers: Cross-sectional Pilot Survey
Authors: Harris M Anne , Kirkham Tracy L
Published: March 2021

Objectives

To pilot recruitment methods for bicycle delivery workers in Toronto, Canada and to assess workers’ experiences with COVID-19 and personal protective equipment (PPE).

Methods

This was a cross-sectional study. An online survey was deployed and advertised via social media with both paid and free postings in July and August of 2020. An incentive draw was used to motivate participation. These analyses summarized descriptive statistics of the sample and variables relevant to COVID-19.

Results

Complete responses were received from 35 participants. No participants reported a diagnosis of COVID-19, however four participants indicated experiencing symptoms. Most participants reported they used PPE, especially masks and/or respirators (97.1%) and 71.4% of participants indicated their employer provided them with PPE (masks or gloves). Participants expressed concern about precarious work and uncertainty about their own COVID-19 exposure risk.

Conclusions

Bicycle delivery workers are a precarious working population that may be difficult to reach for research recruitment purposes. Given their essential role in deliveries during the COVID-19 pandemic, further work is needed to characterize exposures and risks in this population.