bluuebunny/crossref_metadata_2025_split huggingface dataset:
Reconfigurable multifunctional ferrofluid droplet robots
Authors: Fan Xinjian , Dong Xiaoguang , Karacakol Alp C. , Xie Hui , Sitti Metin 
Published: October 2020

Significance
This work proposes reconfigurable multifunctional ferrofluid droplets as soft robots to overcome the limitation of existing magnetically actuated miniature soft robots based on elastomers, i.e., they cannot navigate inside very clustered and constrained spaces and reconfigure their shapes in situ for diverse tasks, due to limited deformability and predesigned shapes. We propose a fundamental mechanism of controlling reconfigurable large deformation (e.g., splitting) and coordinated motions of multiple ferrofluid droplets by programming external magnetic fields spatiotemporally. We employ this mechanism to achieve multiple functionalities, including on-demand liquid-cargo delivery, morphing for efficient and versatile manipulation of delicate objects, and programmable fluidic-mixing function, potentially enabling unprecedented functionalities in lab/organ-on-a-chip, fluidics, bioengineering, and medical device applications, beyond magnetically actuated elastomer-based soft robots.
Identification of a degradation signal at the carboxy terminus of SREBP2: A new role for this domain in cholesterol homeostasis
Authors: Kober Daniel L. , Xu Shimeng , Li Shili , Bajaj Bilkish , Liang Guosheng , Rosenbaum Daniel M. , Radhakrishnan Arun 
Published: October 2020

Significance
Sterol regulatory element-binding proteins (SREBPs) are transcription factors that control production of cholesterol and other lipids. In endoplasmic reticulum (ER) membranes, SREBPs form complexes with Scap, a cholesterol-sensing membrane protein. When cholesterol levels are low, Scap escorts SREBPs from the ER to the Golgi where proteolytic cleavage releases the transcription factor domain that turns on genes involved in cholesterol synthesis. The remainder of SREBP still bound to Scap must be eliminated so that Scap can be recycled to bind additional SREBPs. Here, we discover a degradation signal in SREBP that mediates clearance of the cleaved SREBP fragments from Scap. Such clearance is essential for the recycling of Scap and thus it is a central step in regulation of cholesterol homeostasis.
Effect of marathon characteristics and runners’ time category on pacing profile
Authors: Oficial‐Casado Fran , Uriel Jordi , Pérez‐Soriano Pedro , Priego Quesada Jose Ignacio 
Published: October 2020

ABSTRACTThis study aimed to analyse differences in pacing profiles in four marathon competitions and to explore that pacing per time category. A database of 91,493 runners gathered from 4 different races was analysed (Valencia, Chicago, London and Tokyo Marathon). Participants were categorized in accordance with their completion time. The relative speed of each section for each runner was calculated as a percentage of the average speed for the entire race. In the four marathons studied, the first 5 km differed widely, presenting London the highest relative speeds (5 km: CI95% London vs. Valencia [12.1, 13.6%], p < 0.001 and ES = 2.1; London vs. Chicago [5.5, 7.1%], p < 0.001 and ES = 1.1; London vs. Tokyo [15.2, 16.8%], p < 0.001 and ES = 2.3). Races did not differ at each section for high‐performance runners (sub‐2:30), but differences between races increased as the time category increases (e.g. 35 km and sub‐3:00: CI95% London vs. Tokyo [−3.1, −1.8%], p < 0.001 and ES = 0.7; 35 km and sub‐5:00: London vs. Tokyo [−9.8, −9.2%], p < 0.001 and ES = 1.3). The difference in relative speed between the first and second half of the marathon was higher in London than in the other marathons (e.g. CI95% London vs. Valencia [10.3, 10.8%], p < 0.001 and ES = 1.3). In conclusion, although race characteristics affect pacing, this effect was higher as the category time increases. Race pacing characteristics should be taken into consideration for runners and coaches choosing the race and working on pacing strategies, for researches to extrapolate or interpret results, or for race organizations to improve its pacing characteristics.
Large scale anomalies in the CMB and non-Gaussianity in bouncing cosmologies
Authors: Agullo Ivan , Kranas Dimitrios , Sreenath V 
Published: October 2020

Abstract
We propose that several of the anomalies that have been observed at large angular scales in the CMB have a common origin in a cosmic bounce that took place before the inflationary era. The bounce introduces a new physical scale in the problem, which breaks the almost scale invariance of inflation. As a result, the state of scalar perturbations at the onset of inflation is no longer the Bunch–Davies vacuum, but it rather contains excitations and non-Gaussianity, which are larger for infrared modes. We argue that the combined effect of these excitations and the correlations between CMB modes and longer wavelength perturbations, can account for the observed power suppression, for the dipolar asymmetry, and it can also produce a preference for odd-parity correlations. The model can also alleviate the tension in the lensing amplitude A
L. We adopt a phenomenological viewpoint by considering a family of bounces characterized by a couple of parameters. We identify the minimum set of ingredients needed for our ideas to hold, and point out examples of theories in the literature where these conditions are met.
Constraint algebra in tetrad bigravity
Authors: Soloviev V O 
Published: October 2020

Abstract
The constraint algebra is derived in the second order tetrad Hamiltonian formalism of the bigravity. This is done by a straightforward calculation without involving any insights, implicit functions, and Dirac brackets. The tetrad approach is the only way to present the bigravity action as a linear functional of lapses and shifts and the Hassan–Rosen transform (characterized as ‘a complicated redefinition of the shift variable’ according to the authors) appears here not as an ansatz but as fixing of a Lagrange multiplier. A comparison of this approach with the other ones is provided.
Is gravity the weakest force?
Authors: Shirai Satoshi , Yamazaki Masahito 
Published: October 2020

Abstract
It has recently been suggested that ‘gravity is the weakest force’ in any theory with a suitable UV completion within quantum gravity. One formulation of this statement is the scalar weak gravity conjecture (WGC), which states that gravity is weaker than the force originating from scalar fields. We study the scalar WGC in de Sitter (dS) space, and discuss its low-energy consequences in light of the experimental searches for fifth forces and violations of the equivalence principle. We point out that some versions of the scalar WGC forbid the existence of very light scalar particles, such as the quintessence and axion-like particles. The absence of the quintessence field means that these versions of the scalar WGC are in phenomenological tension with the recently-proposed dS swampland conjecture and its refinements. Some other versions of the scalar WGC escape these constraints, and could have interesting phenomenological consequences.
Randomly evolving Platonic Solids: a zero-player game
Authors: Platini T , Low R 
Published: October 2020

Abstract
We investigate a simple a discrete time random process based on the construction of Platonic solids. As is surprisingly often the case with apparently simple processes, we find some intriguing results, in this case requiring a careful consideration of how the probability distributions describing this process behave. The investigation proceeds by a fruitful combination of geometry, probability and elementary real analysis. We conclude with a consideration of the limiting behaviour of the probability distributions describing the size of the solid as the number of steps grows.
On iteratively regularized predictor–corrector algorithm for parameter identification
*
Authors: Smirnova Alexandra , Bakushinsky Anatoly 
Published: October 2020

Abstract
We study a constrained optimization problem of stable parameter estimation given some noisy (and possibly incomplete) measurements of the state observation operator. In order to find a solution to this problem, we introduce a hybrid regularized predictor–corrector scheme that builds upon both, all-at-once formulation, recently developed by B. Kaltenbacher and her co-authors, and the so-called traditional route, pioneered by A. Bakushinsky. Similar to all-at-once approach, our proposed algorithm does not require solving the constraint equation numerically at every step of the iterative process. At the same time, the predictor–corrector framework of the new method avoids the difficulty of dealing with large solution spaces resulting from all-at-once make-up, which inevitably leads to oversized Jacobian and Hessian approximations. Therefore our predictor–corrector algorithm (PCA) has the potential to save time and storage, which is critical when multiple runs of the iterative scheme are carried out for uncertainty quantification. To assess numerical efficiency of novel PCA, two parameter estimation inverse problems in epidemiology are considered. All experiments are carried out with real data on COVID-19 pandemic in Netherlands and Spain.
A new boson approach for the wobbling motion in even–odd nuclei
Authors: Raduta A A , Raduta C M , Poenaru R 
Published: October 2020

Abstract
A triaxial core rotating around the middle axis, i.e. two-axis, is cranked around the one-axis, due to the coupling of an odd proton from a high j orbital. Using the Bargmann representation of a new and complex boson expansion of the angular momentum components, the eigenvalue equation of the model Hamiltonian acquires a Schrödinger form with a fully separated kinetic energy. From a critical angular momentum, the potential energy term exhibits three minima, two of them being degenerate. Spectra of the deepest wells reflects a chiral-like structure. Energies corresponding to the deepest and local minima respectively, are analytically expressed within a harmonic approximation. Based on a classical analysis, a phase diagram is constructed. It is also shown that the transverse wobbling mode is unstable. The wobbling frequencies corresponding to the deepest minimum are used to quantitatively describe the wobbling properties in 135Pr. Both energies and e.m. transition probabilities are described.
Gap opening in graphene nanoribbons by application of simple shear strain and in-plane electric field
Authors: Bandeira N S , da Costa D R , Chaves A , Farias G A , Filho R N Costa 
Published: October 2020

Abstract
The effects of shear strain and applied in plane electric field on the electronic properties of monolayer graphene nanoribbons (GNRs) are theoretically investigated. Band structures and the probability densities are calculated within the tight-binding model and the mechanical stresses submitted to the GNRs are taken into account by using the theory of linear elasticity with joint modifications in the elongation of the nearest-neighbor vectors and the modification of the hopping parameters. The energy gaps for specific widths of (semiconducting) armchair nanoribbons are verified also in the presence of either strain or field, whereas zigzag nanoribbons are metallic for any value of strain and exhibit a small gap for any value of field. However, our results demonstrate that when both strain and electric field are combined, a significant energy gap is always observed in the band structure, for any width or edge type of the ribbon. Moreover, the obtained total wave function is asymmetric along the ribbon width due to the applied electric field that pushes the electrons to one side of the ribbon and, under shear strain, a peak at the center of the ribbon in the spatial distribution is also observed owing to the preferable localization around the almost undeformed carbon bonds at ribbon center.
A new Wi-Fi dynamic selection of nearest neighbor localization algorithm based on RSS characteristic value extraction by hybrid filtering
Authors: Peng Xuesheng , Chen Ruizhi , Yu Kegen , Guo Guangyi , Ye Feng , Xue Weixing 
Published: October 2020

Abstract
Fingerprinting localization based on Wi-Fi received signal strength (RSS) is the most widely used indoor localization method. It typically includes offline training and online matching phases. The selection of the RSS characteristic value is a key step. The weighted K nearest neighbor (WKNN) algorithm is the most commonly used position-determination algorithm. The mean value of the RSS data collected over a time interval is usually taken as its characteristic value. However, the RSS measurements contain Gaussian and non-Gaussian noise, which cannot be filtered out effectively by the mean value method. The traditional WKNN algorithm adopts a fixed

K

. However, reference points far away from the test point (TP) may be selected as the nearest neighbors to participate in the position calculation, which may result in accuracy degradation. This paper proposes the weighted dynamic K nearest neighbor algorithm (WDKNN-HF), which utilizes a hybrid of particle filtering and Kalman filtering to extract the RSS characteristic value. In the online matching phase, a dynamic K matching algorithm based on Euclidean distances is developed to determine the coordinates of TPs. Two experiments are conducted in two different indoor scenes. Experimental results demonstrate that the proposed algorithm can obtain better positioning accuracy than existing algorithms, such as KNN, WKNN, enhanced-WKNN (EWKNN) and self-adaptive weighted K nearest neighbor (SAWKNN).
Atomic layer deposition of tungsten sulfide using a new metal-organic precursor and H2S: thin film catalyst for water splitting
Authors: Kim Deok-Hyun , Ramesh Rahul , Nandi Dip K , Bae Jong-Seong , Kim Soo-Hyun 
Published: October 2020

Abstract
Transition metal dichalcogenides (TMDs) are extensively researched in the past few years due to their two-dimensional layered structure similar to graphite. This group of materials offers tunable optoelectronic properties depending on the number of layers and therefore have a wide range of applications. Tungsten disulfide (WS2) is one of such TMDs that has been studied relatively less compared to MoS2. Herein, WS
x
thin films are grown on several types of substrates by atomic layer deposition (ALD) using a new metal-organic precursor [tris(hexyne) tungsten monocarbonyl, W(CO)(CH3CH2C≡CCH2CH3)3] and H2S molecules at a relatively low temperature of 300 °C. The typical self-limiting film growth by varying both, precursor and reactant, is obtained with a relatively high growth per cycle value of ∼0.13 nm. Perfect growth linearity with negligible incubation period is also evident in this ALD process. While the as-grown films are amorphous with considerable S-deficiency, they can be crystallized as h-WS2 film by post-annealing in the H2S atmosphere above 700 °C as observed from x-ray diffractometry analysis. Several other analyses like Raman and x-ray photoelectron spectroscopy, transmission electron microscopy, UV–vis. spectroscopy are performed to find out the physical, optical, and microstructural properties of as-grown and annealed films. The post-annealing in H2S helps to promote the S content in the film significantly as confirmed by the Rutherford backscattering spectrometry. Extremely thin (∼4.5 nm), as-grown WS
x
films with excellent conformality (∼100% step coverage) are achieved on the dual trench substrate (minimum width: 15 nm, aspect ratio: 6.3). Finally, the thin films of WS
x
(as-grown and 600/700 °C annealed) on W/Si and carbon cloth substrate are investigated for electrochemical hydrogen evolution reaction (HER). The as-grown WS
x
shows poor performance towards HER and is attributed to the S-deficiency, amorphous character, and oxygen contamination of the WS
x
film. Annealing the WS
x
film at 700 °C results in the formation of a crystalline layered WS2 phase, which significantly improves the HER performance of the electrode. The study reveals the importance of sulfur content and crystallinity on the HER performance of W-based sulfides.
Dual functional modes for nanostructured p-Cu2O/n-Si heterojunction photodiodes
Authors: Huang Chun-Ying , Wei En-Chun , Yuan Chia-Tse 
Published: October 2020

Abstract
Many applications require a photodetector (PD) with multiple functional modes. This study demonstrates a dual functional PD with a simple structure that uses a nanostructured p-Cu2O/n-Si heterojunction. This device features a self-powering characteristic for an open-circuit voltage (V
oc) of 0.5 V and exhibits an external quantum efficiency (EQE) of 3780% at a reverse bias of −5 V. There is a high EQE at low reverse-bias because trapped holes cause charge to be injected from the electrode. The nanostructured p-Cu2O/n-Si heterojunction also has a high response speed (<10 ms) in the self-powered mode because there is a built-in potential within p–n junction. This study shows that a nanostructured p-Cu2O/n-Si heterojunction acts as a self-powered PD for reducing power consumption and as a photomultiplication (PM)-type PD with high internal gain.
Inhomogeneity-mediated systematic reduction of the Schottky barrier in a Au/GaN nanorod film interface
Authors: Pant Rohit Kumar , Roul Basanta , Kumar Singh Deependra , Chowdhury Arun Malla , Nanda K K , Krupanidhi S B 
Published: October 2020

Abstract
Self-aligned GaN nanorods of various densities are grown on an r-plane Al2O3 substrate with Stranski–Krastanov or layer-plus-island growth conditions by using a plasma-assisted molecular beam epitaxy system. These conditions result in the formation of a GaN nanorod matrix on an epitaxial GaN thin film. The orientation of the nanorods was found to be at an inclination of ∼60° from the substrate. As expected, the GaN thin film grows along the [11–20] direction, but interestingly the nanorods have a preferential growth direction along the [0002] axis. The overall structure mimics the Gaussian distribution of Schottky barriers at the metal–semiconductor interface. The GaN nanorod/thin-film matrix systematically causes the well-known Au/GaN Schottky metal–semiconductor interface to display an Ohmic type of behavior. A systematic reduction of the Schottky barrier is observed with an increase in the GaN nanorod density (from 5 to 65 nanorods micron−2). The overall configuration provides a tunable Gaussian distribution of Schottky barriers with nanorod density, which could be extremely useful for replacing conventional multi-level electrode stacking techniques.
Effect of doping profile variation on nanoscale cylindrical gate carbon nanotube field-effect transistor: a computational study using nonequilibrium Green’s function formalism
Authors: Mahdi Muntasir , Hossain Md Anik , Hussain Sazzad , Hasan Mehedi , Zaman Hasan U , Saha Jibesh Kanti 
Published: October 2020

Abstract
The scaling down of modern devices beyond 15 nm has faced major setbacks as it engendered short channel effects which were seemingly inexorable. One of the solutions proposed was to replace the conventional silicon channel with carbon nanotubes (CNTs), giving rise to the carbon nanotube field-effect transistor (CNTFET). CNTs provide unrivaled electrical and mechanical properties which make them an attractive alternative to silicon for channel materials. In this research work, a cylindrical gate CNTFET model is proposed, and its performance is studied and compared with existing experimental results. The performance of the device due to the variation in the doping profile of the source and drain is studied to realize a device that can manifest superior characteristics compared with existing devices. A model with a non-uniform doping profile is proposed that results in a significant reduction in leakage current. The characteristics upon which the performance is evaluated are the on/off current ratio (I
ON/I
OFF), subthreshold swing (SS), and threshold voltage. By adjusting various parameters, a device is constructed with I
ON/I
OFF of 4 × 106, SS of 63 mV dec−1 (approximately), and a threshold voltage of 0.45 V, which performs better than existing devices shown in the literature. All the simulations have been performed by employing the nonequilibrium Green’s function formalism with the self-consistent solution of the Schrödinger and Poisson equations.
Simulations of single event effects in 6T2C-based ferroelectric non-volatile static random access memory
Authors: Wang Jianjian , Bi Jinshun , Liu Gang , Bai Hua , Xi Kai , Li Bo , Ji Lanlong , Majumdar Sandip 
Published: October 2020

Abstract
The single event effects (SEEs) on ferroelectric Hf0.5Zr0.5O2 capacitor-based non-volatile static random access memory (nvSRAM) were investigated by simulation. A nvSRAM cell integrated with two ferroelectric Hf0.5Zr0.5O2 capacitors is proposed in this study. A macro-model of the ferroelectric Hf0.5Zr0.5O2 capacitor, extracted from the real fabricated devices, is utilized for simulation analysis. Fundamental store and recall operations of the proposed nvSRAM design have been demonstrated. An independent double exponential current source was utilized and injected into specific circuit nodes to simulate the heavy ion induced single event transient current. The simulation results show that the transient pulse current is possible to upset the logic state of the memory cell from 1 to 0, but whether it can recover in a short time period after the upset errors depends on the exact value of linear energy transfer for the injected particles. In addition, increasing the remnant polarization (P
r) and decreasing the coercive voltage (V
c) and film thickness of ferroelectric capacitors can mitigate the influence of SEEs, which provides guidance for process hardening techniques aiming at space applications.
Light amplification via PbS quantum dots-doped tapered fiber coupler: model and theory
Authors: Pakarzadeh Hassan , Karimi Mohammad Javad , Mohammadi Zeinab , Taghizadeh Mostafa , Bozorgzadeh Forough 
Published: October 2020

Abstract
In this paper, the gain engineering of a semiconductor quantum dots fiber amplifier (SQDFA) is studied. The optical amplification is realized by exciting the PbS quantum dots coated around the tapered single-mode fiber coupler with an evanescent wave. The gain spectra and saturation properties of the SQDFA are obtained via solving the rate and coupled power equations based on the two-level model. Then, the effect of the signal wavelength, pump power and amplifier length on the saturation characteristics is numerically simulated. The obtained results show that the proposed model is in a good agreement with the previous experimental results. Unique characteristics of the SQDFA such as the broadband optical gain and smooth bandwidth are of great interest for dense wavelength-division multiplexing systems. Therefore, the proposed model show promising applications in the future fiber-optic communications.
Controlling photonic spin Hall effect in graphene-dielectric structure by optical pumping
Authors: Dong Peng , Cheng Jie , Da Haixia , Yan Xiaohong 
Published: October 2020

Abstract
The photonic spin Hall effect (SHE) provides an effective way to manipulate the spin-polarized photons. However, the spin-dependent splitting is very tiny due to the weak spin–orbit coupling, and previous investigations for enhancing this phenomenon have some serious limitations (e.g. inconvenient to tune, inadequate attention in terahertz region). Therefore, controlling and enhancing the photonic SHE in a flexible way is highly desirable, especially for terahertz region. In this contribution, we propose a method to manipulate the photonic SHE by taking advantage of tunable optical properties of graphene via weak optical pumping. We find that photonic SHE of graphene-dielectric structure in terahertz region is quite sensitive to the pumping power. The spin shift for H polarized incident beam can reach its upper limitation under the optimal pumping power, which is related to the zero value of the real part of graphene conductivity. These findings may provide a new degree of freedom for the design of tunable spin-based photonic devices in the future.