bluuebunny/crossref_metadata_2025 huggingface dataset:
Equilibrium shape of core(Fe)–shell(Au) nanoparticles as a function of the metals volume ratio
Authors: Ponchet A. , Combettes S. , Benzo P. , Tarrat N. , Casanove M. J. , Benoit M.
Published: August 2020

The equilibrium shape of nanoparticles is investigated to elucidate the various core–shell morphologies observed in a bimetallic system associating two immiscible metals, iron and gold, that crystallize in the bcc and fcc lattices, respectively. Fe–Au core–shell nanoparticles present a crystalline Fe core embedded in a polycrystalline Au shell, with core and shell morphologies both depending on the Au/Fe volume ratio. A model is proposed to calculate the energy of these nanoparticles as a function of the Fe volume, Au/Fe volume ratio, and the core and shell shape, using the density functional theory-computed energy densities of the metal surfaces and of the two possible Au/Fe interfaces. Three driving forces leading to equilibrium shapes were identified: the strong adhesion of Au on Fe, the minimization of the Au/Fe interface energy that promotes one of the two possible interface types, and the Au surface energy minimization that promotes a 2D–3D Stranski–Krastanov-like transition of the shell. For a low Au/Fe volume ratio, the wetting is the dominant driving force and leads to the same polyhedral shape for the core and the shell, with an octagonal section. For a large Au/Fe ratio, the surface and interface energy minimizations can act independently to form an almost cube-shaped Fe core surrounded by six Au pyramids. The experimental nanoparticle shapes are well reproduced by the model, for both low and large Au/Fe volume ratios.
Crystallization and jamming in narrow fluidized beds
Authors: Cúñez Fernando David , Franklin Erick M.
Published: August 2020

A fluidized bed is basically a suspension of granular material by an ascending fluid in a tube, and it has a rich dynamics that includes clustering and pattern formation. When the ratio between the tube and grain diameters is small, different behaviors can be induced by high confinement effects. Some unexpected and curious behaviors that we investigate in this paper are the crystallization and jamming of grains in liquids with velocities higher than those for incipient fluidization, supposed to maintain the grains fluidized. In our experiments, performed in a vertical tube of transparent material, different grains, water velocities, resting times, and velocity decelerations were used. An analysis of the bed evolution based on image processing shows that, after a decreasing flow that reaches a velocity still higher than that for incipient fluidization, grains become organized in lattice structures of high compactness, where they are trapped though with small fluctuations. These structures are initially localized and grow along time, in a similar manner as happens in phase transitions and glass formation. After a certain time, if the liquid velocity is slightly increased, jamming occurs, with grains being completely blocked and their fluctuation disappearing. We show that different lattice structures appear depending on the grain type. Our results provide new insights into fluidization conditions, glass-like formation, and jamming.
Probing excited-state dynamics with quantum entangled photons: Correspondence to coherent multidimensional spectroscopy
Authors: Ishizaki Akihito
Published: August 2020

Quantum light is a key resource for promoting quantum technology. One such class of technology aims to improve the precision of optical measurements using engineered quantum states of light. In this study, we investigate transmission measurement of frequency-entangled broadband photon pairs generated via parametric down-conversion with a monochromatic laser. It is observed that state-to-state dynamics in the system under study are temporally resolved by adjusting the path difference between the entangled twin beams when the entanglement time is sufficiently short. The non-classical photon correlation enables time-resolved spectroscopy with monochromatic pumping. It is further demonstrated that the signal corresponds to the spectral information along anti-diagonal lines of, for example, two-dimensional Fourier-transformed photon-echo spectra. This correspondence inspires us to anticipate that more elaborately engineered photon states would broaden the availability of quantum light spectroscopy.
Accurate quantum mechanical calculations on deuterated vinylidene isomerization
Authors: Luo Jia , Cao Jianwei , Liu Hao , Bian Wensheng
Published: August 2020

We present accurate quantum dynamics calculations on vinylidene-d2 (fully deuterated vinylidene) isomerization. This is achieved by large-scale parallel computations with an efficient theoretical scheme developed by us in which basis functions are customized for the deuterium migration process. Mode-specific permutation tunneling splittings of vinylidene-d2 states are reported here for the first time, and evident isotope effects are revealed. The A1′, B2′, A1″, and B2″ symmetric vinylidene-d2 states are calculated, and the peaks recently observed in the cryo-SEVI spectra are analyzed, with very good agreement between theory and experiment achieved for the energy levels. In addition, a few vinylidene-d2 states beyond the experimental energy region are reported. Our studies are helpful for acquiring a better understanding of isotope effects in the double-hydrogen migration processes.
Investigation of the drag reduction performance of bionic flexible coating
Authors: Li Luncao , Liu Bing , Hao Hanlin , Li Longyang , Zeng Zhixiang
Published: August 2020

The drag is a crucial factor in reducing the speed of movement and increasing unnecessary energy loss. In this work, inspired by dolphins, five bionic flexible coatings with drag reduction performance were designed and manufactured. First and foremost, the mixed solution, composed of the polydimethylsiloxane and ethyl acetate, was sprayed on aluminum disks with a spray gun, and the bionic flexible coatings were obtained by heating the aluminum disks sprayed with the mixed solution. Afterward, the mechanical properties and surface characteristics of the flexible coatings were characterized. The experimental results for the flexible coatings of drag reduction performance were obtained by using the drag force device. Above all, the parametric study focusing on the flexible coating of the mechanical properties affects the station of flow, which is performed to analyze the impact on drag reduction. Selecting the aluminum disk without any coating as a reference, numerical simulation methods were introduced to explore the drag reduction mechanism of the bionic flexible coating. The results evidence that the drag reduction ratio is 21.6% at the rotation velocity 50 rpm. Under the action of frictional resistance, the coating of elastic deformation caused by the viscoelasticity of the coating like the dolphin skin results in a decrease in frictional resistance of the wall.
Harnessing flow-induced vibration of a D-section cylinder for convective heat transfer augmentation in laminar channel flow
Authors: Kumar Vedant , Garg Hemanshul , Sharma Gaurav , Bhardwaj Rajneesh
Published: August 2020

Flow-induced vibration (FIV) of a D-section cylinder is computationally studied and utilized to augment convective heat transfer in a heated laminar channel flow. An in-house fluid–structure interaction (FSI) solver, based on a sharp-interface immersed boundary method, is employed to solve the flow and thermal fields. In conjunction, a spring–mass system is utilized to solve for the rigid structural dynamics. Using numerical simulations, we highlight that the oscillations of a D-section cylinder are driven by vortex-induced vibration and galloping. It is observed that as the cylinder vibrates, vortices are shed from the apex of the cylinder due to the separating shear layers. These vortices, categorized using shedding patterns, interact with the heated channel walls. This interaction results in disruption of the thermal boundary layer (TBL), thus leading to heat transfer augmentation. The enhancement in thermal performance has been quantified using time and space-averaged Nusselt numbers at the channel walls. It is observed that the oscillation amplitude of the D-section cylinder and the extent of vortex–TBL interaction are crucial for determining heat transfer augmentation. Both symmetric and asymmetric thermal augmentation at the top and bottom channel walls have been reported. Finally, to assess the effectiveness of heat transfer augmentation, the D-section cylinder FIV is compared to other FSI systems operating under similar conditions.
Spectroscopy and electronic structure of the hypermetallic oxide, MgOMg
Authors: Persinger Thomas D. , Frohman Daniel J. , Fawzy Wafaa M. , Heaven Michael C.
Published: August 2020

Electronic spectra for the hypermetallic oxide MgOMg have been observed in the 21 100 cm−1–24 000 cm−1 spectral range using laser induced fluorescence and two-photon resonantly enhanced ionization techniques. Rotationally resolved data confirmed the prediction of a X̃1Σg+ ground state. The spectrum was highly congested due to the optical activity of a low-frequency bending mode and the presence of three isotopologues with significant natural abundances. Ab initio calculations predict a bent equilibrium structure for the Ã1B2 upper state, consistent with the observation of a long progression of the bending vibration mode. However, the vibrational intervals were not reproduced by the theoretical calculations. In part, this discrepancy is attributed to strong vibronic coupling between multiple electronically excited states. Two-photon ionization measurements were used to determine an ionization energy of 6.5800(25) eV.
Understanding the challenges faced in community-based outreach programs aimed at men who have sex with men in urban Indonesia
Authors: Hegarty Benjamin , Nanwani Sandeep , Praptoraharjo Ignatius
Published: August 2020

Abstract

Background
Community-based outreach programs play an important role in the provision of HIV testing, treatment and health care for men who have sex with men (MSM) in Indonesia. However, qualitative studies of community-based HIV programs have mostly focused on clients rather than on outreach workers (OW). The experiences of MSM peer OW provide insights into how to extend and improve community involvement in HIV programs in Indonesia. Methods: This is a qualitative study based on focus group discussions, which brought together MSM OW (n = 14) and healthcare workers (n = 12). This approach facilitated documentation of the challenges associated with community-based outreach programs in Indonesia through a participatory focus group discussion between OW and healthcare workers. Results: Findings are reported in relation to challenges experienced in the context of community outreach, and solutions to the challenges faced by OW. It was found that awareness of a shared commitment to delivering HIV programs can facilitate good relationships between OW and healthcare workers. Conclusion: Future efforts should consider the role of OW within broader relationships, especially with healthcare workers, when developing community-based responses to HIV testing and treatment. Documenting the role of OW can help contribute to an understanding of ways to adapt HIV programs to reduce barriers to access both for those identified as MSM and others who are ambiguously placed in relation to the programmatic use of such categories.
Effects of policy change on wildland fire management strategies: evidence for a paradigm shift in the western US?
Authors: Young Jesse D. , Evans Alexander M. , Iniguez Jose M. , Thode Andrea , Meyer Marc D. , Hedwall Shaula J. , McCaffrey Sarah , Shin Patrick , Huang Ching-Hsun
Published: August 2020

In 2009, new guidance for wildland fire management in the United States expanded the range of strategic options for managers working to reduce the threat of high-severity wildland fire, improve forest health and respond to a changing climate. Markedly, the new guidance provided greater flexibility to manage wildland fires to meet multiple resource objectives. We use Incident Status Summary reports to understand how wildland fire management strategies have differed across the western US in recent years and how management has changed since the 2009 Guidance for Implementation of Federal Wildland Fire Management Policy. When controlling for confounding variation, we found the 2009 Policy Guidance along with other concurrent advances in fire management motivated an estimated 27 to 73% increase in the number of fires managed with expanded strategic options, with only limited evidence of an increase in size or annual area burned. Fire weather captured a manager’s intent and allocation of fire management resources relative to burning conditions, where a manager’s desire and ability to suppress is either complemented by fire weather, at odds with fire weather, or put aside due to other priorities. We highlight opportunities to expand the use of strategic options in fire-adapted forests to improve fuel heterogeneity.
Generating annual estimates of forest fire disturbance in Canada: the National Burned Area Composite
Authors: Hall R. J. , Skakun R. S. , Metsaranta J. M. , Landry R. , Fraser R.H. , Raymond D. , Gartrell M. , Decker V. , Little J.
Published: August 2020

Determining burned area in Canada across fire management agencies is challenging because of different mapping scales and methods. The inconsistent removal of unburned islands and water features from within burned polygon perimeters further complicates the problem. To improve the determination of burned area, the Canada Centre for Mapping and Earth Observation and the Canadian Forest Service developed the National Burned Area Composite (NBAC). The primary data sources for this tool are an automated system to derive fire polygons from 30-m Landsat imagery (Multi-Acquisition Fire Mapping System) and high-quality agency polygons delineated from imagery with spatial resolution ≤30m. For fires not mapped by these sources, the Hotspot and Normalized Difference Vegetation Index Differencing Synergy method was used with 250–1000-m satellite data. From 2004 to 2016, the National Burned Area Composite reported an average of 2.26 Mha burned annually, with considerable interannual variability. Independent assessment of Multi-Acquisition Fire Mapping System polygons achieved an average accuracy of 96% relative to burned-area data with high spatial resolution. Confidence intervals for national area burned statistics averaged±4.3%, suggesting that NBAC contributes relatively little uncertainty to current estimates of the carbon balance of Canada’s forests.
Inducers of the endothelial cell barrier identified through chemogenomic screening in genome-edited hPSC-endothelial cells
Authors: Roudnicky Filip , Zhang Jitao David , Kim Bo Kyoung , Pandya Nikhil J. , Lan Yanjun , Sach-Peltason Lisa , Ragelle Heloise , Strassburger Pamela , Gruener Sabine , Lazendic Mirjana , Uhles Sabine , Revelant Franco , Eidam Oliv , Sturm Gregor , Kueppers Verena , Christensen Klaus , Goldstein Leonard D. , Tzouros Manuel , Banfai Balazs , Modrusan Zora , Graf Martin , Patsch Christoph , Burcin Mark , Meyer Claas A. , Westenskow Peter D. , Cowan Chad A.
Published: August 2020

Significance

Blood vessels in the central nervous system possess unique barrier properties that prevent infiltration of foreign substances and allow for precise delivery of ions, molecules, and immune cells into neural networks. Barrier breakdown is associated with a host of retinal and neurological disorders but few BRB/BBB-enhancing therapies have been developed. To identify novel barrier-inducing factors, we genetically engineered a transcriptional reporter cell line with CRISPR technology for compound library screening. Using this approach, we identified compounds, including a TGF-β receptor inhibitor, RepSox, which functions in vitro to increase barrier resistance in human primary and stem cell-derived endothelial cell lines. These data may inform future therapies for BRB/BBB disorders and retinal/neurological diseases.
Plant richness, turnover, and evolutionary diversity track gradients of stability and ecological opportunity in a megadiversity center
Authors: Colville Jonathan F. , Beale Colin M. , Forest Félix , Altwegg Res , Huntley Brian , Cowling Richard M.
Published: August 2020

Significance

What explains global patterns of diversity—environmental history or ecology? Most studies have focused on latitudinal gradients—the decline of diversity from the tropics to the poles. A problem with this is that it conflates predictions of historical and ecological hypotheses: The productive tropics have also experienced high Cenozoic biome stability. Longitudinal diversity gradients can overcome this constraint. We use a longitudinal diversity gradient in the megadiverse Cape Floristic Region to model species and evolutionary diversity in terms of Pleistocene climate stability and ecological heterogeneity. We find that biome stability is the strongest predictor of diversity measures, and argue that stability, in conjunction with measures of ecological opportunity—other than productivity—may provide a general explanation for global diversity patterns.
Geometric renormalization unravels self-similarity of the multiscale human connectome
Authors: Zheng Muhua , Allard Antoine , Hagmann Patric , Alemán-Gómez Yasser , Serrano M. Ángeles
Published: August 2020

Significance

The architecture of the human brain underlies human behavior and is extremely complex with multiple scales interacting with one another. However, research efforts are typically focused on a single spatial scale. We explored the spatial multiscale organization of the human brain by using two high-quality datasets with connectomes at five anatomical resolutions for 84 healthy subjects. We found that the zoomed-out layers remain self-similar and that a geometric network model, where distances are not Euclidean, predicts the observations by application of a renormalization protocol. Our results prove that the same principles organize brain connectivity at different scales and lead to efficient decentralized communication. Implications extend to debates, like criticality in the brain, and applications, including tools for brain simulation.
Shedding new light on the generation of the visual chromophore
Authors: Palczewski Krzysztof , Kiser Philip D.
Published: August 2020

The visual phototransduction cascade begins with a
cis
–
trans
photoisomerization of a retinylidene chromophore associated with the visual pigments of rod and cone photoreceptors. Visual opsins release their all-
trans
-retinal chromophore following photoactivation, which necessitates the existence of pathways that produce 11-
cis
-retinal for continued formation of visual pigments and sustained vision. Proteins in the retinal pigment epithelium (RPE), a cell layer adjacent to the photoreceptor outer segments, form the well-established “dark” regeneration pathway known as the classical visual cycle. This pathway is sufficient to maintain continuous rod function and support cone photoreceptors as well although its throughput has to be augmented by additional mechanism(s) to maintain pigment levels in the face of high rates of photon capture. Recent studies indicate that the classical visual cycle works together with light-dependent processes in both the RPE and neural retina to ensure adequate 11-
cis
-retinal production under natural illuminances that can span ten orders of magnitude. Further elucidation of the interplay between these complementary systems is fundamental to understanding how cone-mediated vision is sustained in vivo. Here, we describe recent advances in understanding how 11-
cis
-retinal is synthesized via light-dependent mechanisms.
Gaze deflection reveals how gaze cueing is tuned to extract the mind behind the eyes
Authors: Colombatto Clara , Chen Yi-Chia , Scholl Brian J.
Published: August 2020

Significance

We report an empirical study of gaze deflection—a common experience in which you turn to look in a different direction when someone “catches” you staring at them. We show that gaze cueing (the automatic orienting of attention to locations at which others are looking) is far weaker for such displays, even when the actual eye and head movements are identical to more typical intentional gazes. This demonstrates how gaze cueing is driven by the perception of minds, not eyes, and it serves as a case study of both how social dynamics can shape visual attention in a sophisticated manner and how vision science can contribute to our understanding of common social phenomena.
The time-dependent mass of cosmological perturbations in loop quantum cosmology: Dapor–Liegener regularization
Authors: García-Quismondo Alejandro , Mena Marugán Guillermo A , Pérez Gabriel Sánchez
Published: August 2020

In this work, we compute the time-dependent masses that govern the dynamics of scalar and tensor perturbations propagating on an effective flat, homogeneous, and isotropic background within the framework of loop quantum cosmology (LQC), regularized according to the procedure put forward by Dapor and Liegener. To do so, we follow the two main approaches that, in the field of LQC, lead to hyperbolic equations for the perturbations in the ultraviolet sector: the hybrid and dressed metric formalisms. This allows us to compare the masses resulting from both proposals and analyze their positivity in regimes of physical interest: the big bounce and the contracting de Sitter phase in the asymptotic past that is a defining feature of the model under consideration.
Relativistic density functional theory with finite-light-speed correction for the Coulomb interaction: a non-relativistic-reduction-based approach
Authors: Naito Tomoya , Akashi Ryosuke , Liang Haozhao , Tsuneyuki Shinji
Published: August 2020

The Breit correction, the finite-light-speed correction for the Coulomb interaction of the electron–electron interaction in

O

1
/

c

2

, is introduced to density functional theory (DFT) based on the non-relativistic reduction with the local density approximation. Using this newly developed relativistic DFT, it is found that the possible outer-most electron of lawrencium atom is the p orbital instead of the d orbital, which is consistent with the previous calculations based on wave-function theory. A possible explanation of the anomalous behavior of its first ionization energy is also given. This DFT scheme provides a practical calculation method for the study of properties of super-heavy elements.
Proton dynamics in superprotonic Rb3H(SeO4)2 crystal by broadband dielectric spectroscopy
Authors: Ławniczak Paweł , Petzelt Jan , Bovtun Viktor , Savinov Maxim , Kempa Martin , Nuzhnyy Dmitry , Pawłowski Antoni
Published: August 2020

Broadband dielectric and AC conductivity spectra (1 Hz to 1 THz) of the superprotonic single crystal Rb3H(SeO4)2 (RHSe) along the c axis were studied in a wide temperature range 10 K < T < 475 K that covers the ferroelastic (T < 453 K) and superprotonic (T > 453 K) phases. A contribution of the interfacial electrode polarization layers was separated from the bulk electrical properties and the bulk DC conductivity was evaluated above room temperature. The phase transition to the superprotonic phase was shown to be connected with the steep but almost continuous increase in bulk DC conductivity, and with giant permittivity effects due to the enhanced bulk proton hopping and interfacial electrode polarization layers. The AC conductivity scaling analysis confirms validity of the first universality above room temperature. At low temperatures, although the conductivity was low, the frequency dependence of dielectric loss indicates no clear evidence of the nearly constant loss effect, so-called second universality. The bulk (intrinsic) dielectric properties, AC and DC conductivity of the RHSe crystal at frequencies up to 1 GHz are shown to be caused by the thermally activated proton hopping. The increase of the AC conductivity above 100 GHz could be assigned to the low-frequency wing of proton vibrational modes.
A probabilistic Takens theorem
Authors: Barański Krzysztof , Gutman Yonatan , Śpiewak Adam
Published: August 2020

Let

X
⊂

R

N

be a Borel set, μ a Borel probability measure on X and T : X → X a locally Lipschitz and injective map. Fix

k
∈
N

strictly greater than the (Hausdorff) dimension of X and assume that the set of p-periodic points of T has dimension smaller than p for p = 1, …, k − 1. We prove that for a typical polynomial perturbation

h

̃

of a given locally Lipschitz function

h
:
X
→
R

, the k-delay coordinate map

x
↦

(

h

̃

(

x

)

,

h

̃

(

T
x

)

,
…
,

h

̃

(

T

k
−
1

x

)

)

is injective on a set of full μ-measure. This is a probabilistic version of the Takens delay embedding theorem as proven by Sauer, Yorke and Casdagli. We also provide a non-dynamical probabilistic embedding theorem of similar type, which strengthens a previous result by Alberti, Bölcskei, De Lellis, Koliander and Riegler. In both cases, the key improvements compared to the non-probabilistic counterparts are the reduction of the number of required coordinates from 2  dim  X to dim  X and using Hausdorff dimension instead of the box-counting one. We present examples showing how the use of the Hausdorff dimension improves the previously obtained results.
On singularities of stationary isometric deformations
Authors: Eberhard Peter , Hornung Peter
Published: August 2020

Unstretchable thin elastic plates such as paper can be modelled as intrinsically flat W
2,2 isometric immersions from a domain in

R

2

into

R

3

. In previous work it has been shown that if such an isometric immersion minimizes the elastic energy, then it is smooth away from a singular set consisting of three different subsets. In the present paper, we show that each of these singular subsets can indeed occur and that regularity may indeed fail there.
Prediction of the Ki-67 marker index in hepatocellular carcinoma based on CT radiomics features
Authors: Wu Hongzhen , Han Xiaorui , Wang Zihua , Mo Lei , Liu Weifeng , Guo Yuan , Wei Xinhua , Jiang Xinqing
Published: August 2020

The noninvasive detection of tumor proliferation is of great value and the Ki-67 is a biomarker of tumor proliferation. We hypothesized that radiomics characteristics may be related to tumor proliferation. To evaluate whether computed tomography (CT) radiomics feature analyses could aid in assessing the Ki-67 marker index in hepatocellular carcinoma (HCC), we retrospectively analyzed preoperative CT findings of 74 patients with HCC. The texture feature calculations were computed from MaZda 4.6 software, and the sequential forward selection algorithm was used as the selection method. The correlation between radiomics features and the Ki-67 marker index, as well as the difference between low Ki-67 (<10%) and high Ki-67 (≥10%) groups were evaluated. A simple logistic regression model was used to evaluate the associations between texture features and high Ki-67, and receiver operating characteristic analysis was performed on important parameters to assess the ability of radiomics characteristics to distinguish the high Ki-67 group from the low Ki-67 group. Contrast, correlation, and inverse difference moment (IDM) were significantly different (P< 0.001) between the low and high Ki-67 groups. Contrast (odds ratio [OR] = 0.957; 95% confidence interval [CI]: 0.926-0.990,P= 0.01) and correlation (OR = 2.5☆105; 95% CI: 7.560-8.9☆109;P= 0.019) were considered independent risk factors for combined model building with logistic regression. Angular second moment (r= −0.285,P= 0.014), contrast (r= −0.449,P< 0.001), correlation (r= 0.552,P< 0.001), IDM (r= 0.458,P< 0.001), and entropy (r= 0.285,P= 0.014) strongly correlated with the Ki-67 scores. Contrast, correlation, and the combined predictor were predictive of Ki-67 status (P< 0.001), with areas under the curve ranging from 0.777 to 0.836. The radiomics characteristics of CT have potential as biomarkers for predicting Ki-67 status in patients with HCC. These findings suggest that the radiomics features of CT might be used as a noninvasive measure of cellular proliferation in HCC.
Effect of annealing ambient gases on the bias stability of amorphous SnSiO thin-film transistors
Authors: Yang Jianwen , Cao Duo , Lin Dong , Liu Feng
Published: August 2020

The effect of different annealing ambient gases on the initial electrical properties and bias stability of amorphous tin silicon oxide (a-SnSiO) thin-film transistors (TFTs) is examined in this study. At an annealing temperature of 350 °C, the SnSiO film remained amorphous with excellent transmittance regardless of the annealing environment. The presence of oxygen during annealing (such as in air and O2) could reduce the mobility of the TFTs and create more oxygen-related defect states, thereby reducing the bias stability. In contrast, nitrogen-annealed TFTs showed maximum mobility and optimal bias stability. The corresponding mobility reached 8.6 cm2V−1s−1, the threshold voltage was 0.2 V and the subthreshold swing value was 0.7 V dec−1.
Visible light photoconductivity studies of gold nanoparticle embedded ZnO thin films for photo detector application
Authors: Sekhar Muddam Raja , Kumar Rashmi Ranjan , Kumari Suman , Laha Ranjit , Pandey Saurabh Kumar , Kar Manoranjan
Published: August 2020

This report demonstrates the visible photo response of gold nanoparticles (AuNPs) embedded ZnO nanocomposite (AuNPs-ZnO) thin films. The AuNPs-ZnO films were prepared by sandwiching DC sputtered AuNPs in between two RF sputtered ZnO layers deposited on p-Si. Crystal phase purity and surface morphology were characterized by the x-ray diffraction and scanning electron microscope. The formation of AuNPs was confirmed by observing the plasmonic dip in optical transmittance. Photoconductivity study was done by recording current–voltage characteristics of the films in the presence of visible light. The ratio of light to dark current was found to be enhanced by two to three orders of magnitude with the inclusion of AuNPs. The observed photocurrent enhancement was found to vary with both AuNPs concentration and sandwich thickness. The highest responsivity observed with the fabricated nanocomposite films was of 0.012 A W−1. The dominant reason for the visible photoconductivity and for the enhancement in photocurrent was ascribed to the plasmonic properties of AuNPs-ZnO composite film. This study paves a new approach to design and fabricate devices for optoelectronic applications.
Spatial structure of lasing modes in wave-chaotic semiconductor microcavities
Authors: Bittner Stefan , Kim Kyungduk , Zeng Yongquan , Wang Qi Jie , Cao Hui
Published: August 2020

We present experimental and numerical studies of broad-area semiconductor lasers with chaotic ray dynamics. The emission intensity distributions at the cavity boundaries are measured and compared to ray tracing simulations and numerical calculations of the passive cavity modes. We study two different cavity geometries, a D-cavity and a stadium, both of which feature fully chaotic ray dynamics. While the far-field distributions exhibit fairly homogeneous emission in all directions, the emission intensity distributions at the cavity boundary are highly inhomogeneous, reflecting the non-uniform intensity distributions inside the cavities. The excellent agreement between experiments and simulations demonstrates that the intensity distributions of wave-chaotic semiconductor lasers are primarily determined by the cavity geometry. This is in contrast to conventional Fabry–Perot broad-area lasers for which the intensity distributions are to a large degree determined by the nonlinear interaction of the lasing modes with the semiconductor gain medium.
Parameter-dependent unitary transformation approach for quantum Rabi model
Authors: Zhang Degang
Published: August 2020

Quantum Rabi model has been exactly solved by employing the parameter-dependent unitary transformation method in both the occupation number representation and the Bargmann space. The analytical expressions for the complete energy spectrum consisting of two double-fold degenerate sub-energy spectra are presented in the whole range of all the physical parameters. Each energy level is determined by a parameter in the unitary transformation, which obeys a highly nonlinear equation. The corresponding eigenfunction is a convergent infinite series in terms of the physical parameters. Due to the level crossings between the neighboring eigenstates at certain physical parameter values, such the degeneracies could lead to novel physical phenomena in the two-level system with the light–matter interaction.
Estimating the privacy of quantum-random numbers
Authors: Seiler Johannes , Strohm Thomas , Schleich Wolfgang P
Published: August 2020

We analyze the information an attacker can obtain on the numbers generated by a user by measurements on a subsystem of a system consisting of two entangled two-level systems. The attacker and the user make measurements on their respective subsystems, only. Already the knowledge of the density matrix of the subsystem of the user completely determines the upper bound on the information accessible to the attacker. We compare and contrast this information to the appropriate bounds provided by quantum state discrimination.
High-fidelity vibrokinetic stimulation induces sustained changes in intercortical coherence during a cinematic experience
Authors: Boasen J , Giroux F , Duchesneau M O , Sénécal S , Léger P M , Ménard J F
Published: August 2020

Objective.High-fidelity vibrokinetic (HFVK) technology is widely used to enhance the immersiveness of audiovisual (AV) entertainment experiences. However, despite evidence that HFVK technology does subjectively enhance AV immersion, the underlying mechanism has not been clarified. Neurophysiological studies could provide important evidence to illuminate this mechanism, thereby benefiting HFVK stimulus design, and facilitating expansion of HFVK technology.Approach.We conducted a between-subjects (VK,N= 11; Control,N= 9) exploratory study to measure the effect of HFVK stimulation through an HFVK seat on electroencephalographic cortical activity during an AV cinematic experience. Subjective appreciation of the experience was assessed and incorporated into statistical models exploring the effects of HFVK stimulation across cortical brain areas. We separately analyzed alpha-band (8–12 Hz) and theta-band (5–7 Hz) activities as indices of engagement and sensory processing, respectively. We also performed theta-band (5–7 Hz) coherence analyses using cortical seed areas identified from the theta activity analysis.Main results.The right fusiform gyrus, inferiotemporal gyrus, and supramarginal gyrus, known for emotion, AV-spatial, and vestibular processing, were identified as seeds from theta analyses. Coherence from these areas was uniformly enhanced in HFVK subjects in right motor areas, albeit predominantly in those who were appreciative. Meanwhile, compared to control subjects, HFVK subjects exhibited uniform interhemispheric decoherence with the left insula, which is important for self-processing.Significance.The results collectively point to sustained decoherence between sensory and self-processing as a possible mechanism for how HFVK increases immersion, and that coordination of emotional, spatial, and vestibular processing hubs with the motor system may be required for appreciation of the HFVK-enhanced experience. Overall, this study offers the first ever demonstration that HFVK stimulation has a real and sustained effect on brain activity during a cinematic experience.
Rapid motor fluctuations reveal short-timescale neurophysiological biomarkers of Parkinson’s disease
Authors: Ahn Minkyu , Lee Shane , Lauro Peter M , Schaeffer Erin L , Akbar Umer , Asaad Wael F
Published: August 2020

Objective.Identifying neural activity biomarkers of brain disease is essential to provide objective estimates of disease burden, obtain reliable feedback regarding therapeutic efficacy, and potentially to serve as a source of control for closed-loop neuromodulation. In Parkinson’s disease (PD), microelectrode recordings (MER) are routinely performed in the basal ganglia to guide electrode implantation for deep brain stimulation (DBS). While pathologically-excessive oscillatory activity has been observed and linked to PD motor dysfunction broadly, the extent to which these signals provide quantitative information about disease expression and fluctuations, particularly at short timescales, is unknown. Furthermore, the degree to which informative signal features are similar or different across patients has not been rigorously investigated. We sought to determine the extent to which motor error in PD across patients can be decoded on a rapid timescale using spectral features of neural activity.Approach.Here, we recorded neural activity from the subthalamic nucleus (STN) of subjects with PD undergoing awake DBS surgery while they performed an objective, continuous behavioral assessment that synthesized heterogenous PD motor manifestations to generate a scalar measure of motor dysfunction at short timescales. We then leveraged natural motor performance variations as a ‘ground truth’ to identify corresponding neurophysiological biomarkers.Main results.Support vector machines using multi-spectral decoding of neural signals from the STN succeeded in tracking the degree of motor impairment at short timescales (as short as one second). Spectral power across a wide range of frequencies, beyond the classic ‘β’ oscillations, contributed to this decoding, and multi-spectral models consistently outperformed those generated using more isolated frequency bands. While generalized decoding models derived across subjects were able to estimate motor impairment, patient-specific models typically performed better.Significance.These results demonstrate that quantitative information about short-timescale PD motor dysfunction is available in STN neural activity, distributed across various patient-specific spectral components, such that an individualized approach will be critical to fully harness this information for optimal disease tracking and closed-loop neuromodulation.
The dependence structure and co-movement of Cryptocurrency based Bayesian approach
Authors: Chaiboonsri Anuphak Saosaovaphak Chukiat , Wannapan Satawat
Published: August 2020

Cryptocurrencies are unique and extra-ordinary currencies which to be econometrically forced into the linear model due to their systematic complexity and extreme movements. This paper was conducted to provide an alternative analysis as a solution for escaping the restrictions of traditional linear assumptions. Five predominant digital currencies such as Bitcoin (BTC), Stellar network (XLM), Litecoin (LTC), Ethereum Classic (ETC), and IOTA were chosen to be employed in the multiple processes based on Bayesian approaches. Market dominance and data regime classifications are the essential components that lead to successfully investigate the dependent structures and co-movements in the digital financial market. The empirical findings could assume that the modern time-series data was meticulously estimated by the flexible modern tool. Bayesian statistics and simulations have the sufficient potency as the suitable solution.
A neural network forecasting of relativistic electron flux at geostationary orbit: solar activity phase dependence
Authors: Yeeram T
Published: August 2020

Geostationary-satellite anomalies are mainly caused by extreme space environment such as flux enhancements of relativistic electrons. A prediction of the relativistic electrons at geostationary orbit (GEO) is crucial to alert of the flux enhancements before it reaches a harmful condition. This work investigates contribution of solar activities at various phases in the daily electron flux (E > 2 MeV) at GEO measured by GOES satellites during the solar cycles 23-24. An alternative method based on the solar activity and feed forward neural network (NN) scheme with back-propagation learning in Waikato Environment for Knowledge Analysis is adopted to predict the electron fluxes in GEO by sorting the solar activity into maximum, descending, and ascending phases. As the model inputs, the historical daily sum K
p and the > 2 MeV electron fluxes are used. Results indicate that the prediction capability of the NN model is dependent on the solar activity in relation to the sum K
p. Crossing the test over the similar solar phases gives a better prediction result than crossing over different phases. The NN model based on the lagged sum K
p and log-flux input are more suitable for the forecasting during the descending and ascending phases, while the lagged log-flux input is more suitable during the maximum phase.
Change Detection for the Past Three Decades Using Geospatial Approach in Lake Chad, Central Africa
Authors: Hussaini A , Mahmud M R , Tang K K W
Published: August 2020

Lakes are extremely touchy and dynamic parts of the earth and have a pivotal part in the farming, environment, industrial and domestic purposes. In Central Africa, Lake Chad Basin (LCB) has observed an uninterrupted decrease in its water level for the past decades as a result of certain variables such as climate change and over-abstraction, and likewise part of dry spells. The aforementioned challenges have serious effects on the standard living of the people in a particular area as well as the lake natural resources. The current study was planned to assess the changes of a lake for the past three epochs, then the Lake Chad satellite imageries include OLI, ETM+, and TM were evaluated with a view to came up with some land cover changes throughout these epochs: 1985, 2000, and 2015. All the scenes were subjected to the pre-processing stage to ensure the originality of the information, and “supervised classification was implemented for land cover change analysis. Then the overall accuracies of the classification of Landsat-TM is 93.80, Landsat-ETM+ is 90.80, and Landsat-OLI is 86.20 respectively. The outcome demonstrates that there is a continuous decline of water bodies, barren land, and shrub, with a rapid increment of farmland and gallery forest”.
Prospecting Fe-Skarn mineralization using ASTER satellite data: case study from Ravanj village, Markazi Province, Iran
Authors: Kiani Omid , Ansari Abdolhamid , Pour Amin Beiranvand , Muslim Aidy M
Published: August 2020

The study area is located in Iran central zone and Urumieh-Dokhtar volcanoplutonic belt. Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) satellite data was used to identify alteration zones associated with Fe-Skarn mineralization in the Ravanj village, Markazi Province, Iran. Argillic, phyllic and propylitic alteration zones are typically associated with Fe-Skarn mineralization in the study area. In this research, the Selective Principal Component Analysis (SPCA) method was applied to VNIR + SWIR bands of ASTER remote sensing data. Bands 1, 4, 6 and 8 were designated for identification clay minerals. Bands 4, 5, and 6 were selected for argillic alteration mapping. Bands 1, 2, and 4 were used to identification iron oxides/hydroxide minerals. Bands 5, 6, and 7 were chosen to map phyllic alteration zones. Bands 7, 8, and 9 were nominated to specify propylitic alteration mapping. According to the eigenvector statistics calculated using SPCA for ASTER, inverse SPC4 image identified clay minerals and SPC2 images detected argillic alteration, oxides/hydroxide minerals, phyllic alteration and propylitic alteration. In this paper, SPCA technique is an appropriate method because of the distinction between alteartion minerals, vegetation for Fe-Skarn mineralization exploration.
The Fixed wing UAV usage on Land use Mapping for gazetted Royal land in Malaysia
Authors: Noor Norzailawati Mohd , Harun Norzalina , Abdullah Alias
Published: August 2020

The study deals with the usage of fixed wing unmanned aerial vehicle (UAV) in verifying boundary for gazetted royal land, which the other sight of efficacy of UAV has been tested in area of urban planning. The specific flight planning had been arranged and tested to royal land of Pekan in order to identify the settlement (kampongs) boundaries. Royal land in Pekan was the significant land that existed since 1919, which established under the Royal land Enactment 1919. It accommodated more five thousand residents in the 919 hectares of area with five villages (kampongs). The combination method of aerial mapping and vector digitization in structured a spatial database have been conducted by combining both output from UAV and GIS. The finding shows the royal land boundary was clearly identified in UAV orthophoto; further refine output of its database in GIS data. The additional info building footprints in 5 kampongs land lots also appeared very well in final output. Result shows that, the simple conclusion on the efficacy of fixed wing UAV in managing a land in urban planning, it also proved the dependency of decision makers should oriented more on geospatial applications since it was reliable and able to be used in many planning aspects in order to ensure a sustainability and resiliency of living.
Vegetation Indices for Identifying Melaleuca Forest from Multispectral Satellite Sensors
Authors: Omar Hamdan , Misman Muhamad Afizzul , Yaakub Siti Yasmin
Published: August 2020

Melaleuca forest or locally known as Gelam forest mostly occur in beach ridges interspersed with swales (BRIS) sandy areas, coastal, wetland, peatland, and lowland regions. It is a mono-specific species dominance ecosystem, where Melaleuca cajuputi trees are dominant. It is fringing along the coast of Terengganu and Kelantan and certain parts along the west coast of Peninsular Malaysia. The landscape is small but it has equal importance to other ecosystems in terms of local environmental functions and economic contributions. The benefits include timber for building constructions and furniture and other traditional uses, such as for fuel wood, charcoal, tea-tree, honeybee breeding areas and others. However, this forest is inevitable from threats by anthropogenic activities such as land clearing and conversion to other land uses that can affect the ecosystem. These activities occur because most of this ecosystem reside on stateland areas, where development is rapid. Only small patches of this forest was protected as Permanent Forest Reserve, which is secure from any threat. Currently the information about the tracts and extents of this forest is very scarce. Therefore, this study was carried out to acquire latest information on the distribution and extent of Melaleuca forest in Peninsular Malaysia through the utilization of remotely sensed data. Optical images from Landsat-8 OLI were used as primary input for this study. Spectral characteristic from visible and infrared regions were analyzed to produce a specific vegetation index for recognizing Melaleuca forest ecosystem on the images. The study demonstrated that the Melaleuca forest covers some 23,000 ha in Peninsular Malaysia that are intact but vulnerable to surrounding threats. The findings of study should attract attentions from the relevant State Governments to take appropriate management actions to protect this unique and priceless ecosystem in the future.