bluuebunny/crossref_metadata_2025 huggingface dataset:
Cargo competition for a dimerization interface restricts and stabilizes a bacterial protease adaptor
Authors: Kuhlmann Nathan J. , Doxsey Dylan , Chien Peter
Published: April 2021

Significance

Energy-dependent proteases broadly regulate bacterial physiology and development. Adaptor proteins tune the substrate specificity of proteases by selectively delivering cargo and themselves can be degraded. We find that the RcdA adaptor forms homodimers that are degraded by the ClpXP protease. Cargo binding disrupts the dimer interface, stabilizing the adaptor, and provides a model for how adaptor degradation can be controlled. Mapping the surfaces responsible for cargo binding shows that different overlapping regions of the dimer interface are tailored to different substrates. Our results suggest a mode of control that provides robust adaptor activity subject to buffering by cargo demand.
Sensitivity of grassland carbon pools to plant diversity, elevated CO
2
, and soil nitrogen addition over 19 years
Authors: Pastore Melissa A. , Hobbie Sarah E. , Reich Peter B.
Published: April 2021

Significance

The long-term effects of rising atmospheric carbon dioxide (CO
2
), high rates of nitrogen deposition, and declining plant biodiversity on ecosystem carbon pools are uncertain and rarely assessed in concert yet represent key feedbacks to global climate change. In a 19-y study in an open-air grassland experiment, increasing planted species richness substantially enhanced ecosystem carbon storage, while elevated CO
2
and nitrogen addition treatments had only modest effects. Effects of the three global changes were largely additive, and stronger effects of species richness compared with CO
2
or nitrogen resulted from large enhancements in plant productivity relative to ecosystem losses. Our results suggest that biodiversity losses may influence carbon storage as much as or more than rising CO
2
or high nitrogen deposition rates.
Global wind patterns shape genetic differentiation, asymmetric gene flow, and genetic diversity in trees
Authors: Kling Matthew M. , Ackerly David D.
Published: April 2021

Significance

It is unknown whether wind currents shape large-scale gene flow in terrestrial organisms such as plants, though analogous river and ocean currents are known to strongly influence genetic patterns in aquatic organisms. We use newly developed “windscape” connectivity models in combination with a global multispecies forest genetics data set to demonstrate that wind shapes several distinct large-scale genetic patterns in many tree species, including population differentiation, migration direction, and genetic diversity. These findings advance our understanding of the spatial ecology and evolution of wind-dispersed and wind-pollinated plants. They also suggest that the geography of wind strength and direction could potentially influence patterns of forest vulnerability to human pressures like habitat fragmentation and climate change.
Highly public anti-Black violence is associated with poor mental health days for Black Americans
Authors: Curtis David S. , Washburn Tessa , Lee Hedwig , Smith Ken R. , Kim Jaewhan , Martz Connor D. , Kramer Michael R. , Chae David H.
Published: April 2021

Significance

Violent acts that are widely publicized and perceived as anti-Black may harm the mental health of observers, particularly Black Americans. We identified 49 incidents of racial violence in the United States, occurring between 2013 and 2017 and receiving widely varying levels of search interest. We show that Black but not White Americans reported poorer mental health in weeks when two incidents of anti-Black violence occurred and when national interest was higher. Reducing racial violence, including police killings of Black individuals, is likely to benefit the mental health of Black Americans nationally.
PIP
2
corrects cerebral blood flow deficits in small vessel disease by rescuing capillary Kir2.1 activity
Authors: Dabertrand Fabrice , Harraz Osama F. , Koide Masayo , Longden Thomas A. , Rosehart Amanda C. , Hill-Eubanks David C. , Joutel Anne , Nelson Mark T.
Published: April 2021

Significance

Years before the emergence of infarctions or significant cognitive decline, patients with cerebral small vessel disease (SVD) show a deterioration in the ability of the brain to augment blood flow locally in response to increases in neuronal activity (functional hyperemia). Using a well-characterized genetic mouse model of a hereditary form of SVD, we determined the molecular defect at play in capillary endothelial cells. We found that SVD is associated with reduced synthesis of the phospholipid PIP
2
, which prevents the Kir2.1 channel-initiated capillary-to-arteriole electrical signaling that supports vasodilatory responses during functional hyperemia. We further show that systemic injection of exogenous PIP
2
is sufficient to rescue this deficit in SVD mice, restoring adequate cerebral blood flow in response to neuronal activation.
Trirachys holosericeus (apple stem borer).
Authors: Haack Robert A.
Published: April 2021

Trirachys holosericeus, a highly polyphagous longhorned beetle, is native to southern Asia from Pakistan to the Philippines. It is a stem-boring pest in natural and planted forests and fruit trees. It attacks primarily hardwoods, and at least one conifer. Both healthy and stressed trees are attacked, often leading to crown dieback and possibly tree death after one or more years of infestation. Cut logs can remain attractive to egg-laying adults for nearly a year after felling. T. holosericeus has not become established outside its native range of Asia, but it could be moved inadvertently in live plants, logs, and solid wood packaging. Chemical treatments, including injecting insecticides into active galleries, are often used on live trees, especially fruit trees. In forest stands, heavily infested trees are often cut and destroyed. For recently cut logs, rapid transport to sawmills and quick utilization, or at least debarking, are recommended.
Copaifera officinalis (copaiba balsam).
Authors: Rojas-Sandoval Julissa , Acevedo-Rodríguez Pedro
Published: April 2021

A datasheet on Copaifera officinalis covering, as an economically important tree, its taxonomy, importance, silviculture, distribution, biology and ecology, uses, products and pests.
A manifestly covariant theory of multifield stochastic inflation in phase space: solving the discretisation ambiguity in stochastic inflation
Authors: Pinol Lucas , Renaux-Petel Sébastien , Tada Yuichiro
Published: April 2021

Stochastic inflation is an effective theory describing the
super-Hubble, coarse-grained, scalar fields driving inflation, by a
set of Langevin equations. We previously highlighted the difficulty
of deriving a theory of stochastic inflation that is invariant under
field redefinitions, and the link with the ambiguity of
discretisation schemes defining stochastic differential equations.
In this paper, we solve the issue of these "inflationary stochastic
anomalies" by using the Stratonovich discretisation satisfying
general covariance, and identifying that the quantum nature of the
fluctuating fields entails the existence of a preferred frame
defining independent stochastic noises. Moreover, we derive
physically equivalent Itô-Langevin equations that are manifestly
covariant and well suited for numerical computations. These
equations are formulated in the general context of multifield
inflation with curved field space, taking into account the coupling
to gravity as well as the full phase space in the Hamiltonian
language, but this resolution is also relevant in simpler
single-field setups. We also develop a path-integral derivation of
these equations, which solves conceptual issues of the heuristic
approach made at the level of the classical equations of motion, and
allows in principle to compute corrections to the stochastic
formalism. Using the Schwinger-Keldysh formalism, we integrate out
small-scale fluctuations, derive the influence action that describes
their effects on the coarse-grained fields, and show how the
resulting coarse-grained effective Hamiltonian action can be
interpreted to derive Langevin equations with manifestly real
noises. Although the corresponding dynamics is not rigorously
Markovian, we show the covariant, phase-space Fokker-Planck equation
for the Probability Density Function of fields and momenta when the
Markovian approximation is relevant, and we give analytical
approximations for the noises' amplitudes in multifield scenarios.
Static response and Love numbers of Schwarzschild black holes
Authors: Hui Lam , Joyce Austin , Penco Riccardo , Santoni Luca , Solomon Adam R.
Published: April 2021

We derive the quadratic action for the physical degrees of freedom of massless spin-0, spin-1, and spin-2 perturbations on a Schwarzschild-(A)dS background in arbitrary dimensions. We then use these results to compute the static response of asymptotically flat Schwarzschild black holes to external fields. Our analysis reproduces known facts about black hole Love numbers — in particular that they vanish for all types of perturbation in four spacetime dimensions — but also leads to new results. For instance, we find that neutral Schwarzschild black holes polarize in the presence of an electromagnetic background in any number of spacetime dimensions except four. Moreover, we calculate for the first time black hole Love numbers for vector-type gravitational perturbations in higher dimensions and find that they generically do not vanish. Along the way, we shed some light on an apparent discrepancy between previous results in the literature, and clarify some aspects of the matching between perturbative calculations of static response on a Schwarzschild background and the point-particle effective theory.
Chromatin stability generated by stochastic binding and unbinding of cross-linkers at looping sites revealed by Markov models
Authors: Papale Andrea , Holcman David
Published: April 2021

Chromatin loops inside the nucleus can be stable for a very long time, which remains poorly understood. Such a time is crucial for chromatin organization maintenance and stability. We explore here several physical scenarios, where loop maintenance is due to diffusing cross-linkers (cohesin stabilized by two CTCF molecules) that can bind and unbind at the base of chromatin loops. Using a Markov chain approach to coarse-grain the binding and unbinding, we consider that a stable loop disappears when the last cross-linker is unbound. We derive expressions for this last passage time that we use to quantify the loop stability for various parameters, such as the chemical rate constant or the number of cross-linkers. The present analysis suggests that the balance between binding and unbinding events regulates the number of cross-linkers in place, based on a positive feed-back mechanism that stabilizes the loop over long-time. To conclude, we found that short- and long-lasting stable loops can vary from minutes to the entire cell cycle lifetime, when the number of cross-linkers increases from 1 to 10. This result suggests that a large spectrum of loop time scales is expected with such a few numbers of cross-linkers per local binding sites.
Research on multiple-image encryption scheme based on joint power spectral division multiplexing and ghost imaging
Authors: Yang Wang , Leihong Zhang , Dawei Zhang , Kaimin Wang
Published: April 2021

Since there are problems of easy cross-talk, large ciphertext transmission and low security in the process of multiple-image encryption, in order to solve these problems, a multiple-image encryption algorithm based on joint power spectral division multiplexing and ghost imaging (GI) is proposed. The joint transform correlator is combined with GI to realize ‘one encryption to one key’, which improves the security of the encryption system. Joint power spectrum (JPS) is compressed by the iterative restoration algorithm to reduce the transmissions of ciphertext. The joint power spectral division multiplexing is used, and the optimized phase mask is linearly superposed. The JPS of each channel has different positions on the spectrum plane, and then the non-crosstalk superposition is realized by window filtering. In this paper, the security, robustness, and encryption capacity of the encryption system are verified by numerical simulation.
Multiple-image encryption based on Toeplitz matrix ghost imaging and elliptic curve cryptography
Authors: Zhixiang Bian , Leihong Zhang , Hualong Ye , Kaimin Wang , Dawei Zhang
Published: April 2021

To improve the security of encryption systems, we propose a multiple-image encryption method via Toeplitz matrix ghost imaging and elliptic curve cryptography. Specifically, each unencrypted image is firstly compressed using wavelet transformation. Compressed images are merged into a single image via spatial multiplexing technology. Then, based on the ghost imaging, the phase mask matrix of the speckle sequence is modulated into a random Toeplitz matrix, through the logistic mapping sequence to achieve the encryption of the combined image. The detection data of all images is obtained through a bucket detector. Finally, the obtained detection data is encrypted twice using an elliptic curve asymmetric cryptographic algorithm to obtain the final ciphertext. In the decryption process, images are recovered using elliptic curve, compressive sensing technology and inverse wavelet transformation. This method provides strong security features for encryption systems. The basic principle of the encryption scheme is analyzed theoretically, and the security and robustness of the proposed method are verified by numerical simulation.
Hydrodynamics of the atomic Bose–Einstein condensate beyond the mean-field approximation
Authors: Andreev Pavel A
Published: April 2021

Several hydrodynamic models of the atomic Bose–Einstein condensate (BEC) obtained beyond the mean-field approximation are discussed together from a single point of view. All these models are derived from the microscopic quantum description. The derivation is made within the many-particle quantum hydrodynamics method suggested by L Kuz’menkov. The derivation is demonstrated and discussed for the mean-field regime revealing the Gross–Pitaevskii equation as the simplest illustration. It appears in the first order by the interaction radius. Generalization of the hydrodynamic Euler equation obtained in the third order by the interaction radius is discussed. It includes the contribution of the isotropic short-range interaction (SRI) presented by the third space derivative of the square of concentration. The Euler equation also includes the contribution of the anisotropic part of the SRI proportional to the second order spherical function. A systematic account of the quantum fluctuations in terms of the many-particle quantum hydrodynamics method requires the extension of the set of hydrodynamic equations from the couple continuity and Euler equations to the set of four equations which also includes the pressure evolution equation and the evolution equation for the third rank tensor of the pressure flux. The pressure evolution equation contains no interaction contribution in the first order by the interaction radius. The source of the quantum fluctuations is in the interaction caused term existing in the third rank tensor evolution equation which is obtained in the first order by the interaction radius. The presented models are considered for the single-component BECs.
Acceleration of heavy ions in inverse free electron laser
Authors: Avreline Nikolai , Kutsaev Ph. D. Sergey V , Avreline Alexandre , Murokh Ph. D. Alex
Published: April 2021

In conventional linear accelerators, the beam is accelerated with a synchronous harmonic of the radio frequency field where the electric field component is collinear with the beam direction. This approach requires the design of complex accelerating structures, especially for low-energy heavy ions. If the beam motion were sustainably coupled to transverse electromagnetic fields, this could significantly simplify the accelerating structure design, and even allow acceleration with free-space waves. However, despite the long history of the proposed concept for accelerating low-velocity ion beams, it has not found practical application, partially because of the complexity of the technical design. In this paper, we present a practical design approach for this undulator-based accelerator for low-energy heavy-ions, reminiscent of the inverse free electron laser operating principle, but in a different parameter space.
Magnetism and giant magnetocaloric effect in rare-earth-based compounds R
3BWO9 (R = Gd, Dy, Ho)*
Authors: Li Lu-Ling , Yue Xiao-Yu , Zhang Wen-Jing , Bao Hu , Wu Dan-Dan , Liang Hui , Wang Yi-Yan , Sun Yan , Li Qiu-Ju , Sun Xue-Feng
Published: April 2021

The magnetism and magnetocaloric effect (MCE) of rare-earth-based tungstate compounds R
3BWO9 (R = Gd, Dy, Ho) have been studied by magnetic susceptibility, isothermal magnetization, and specific heat measurements. No obvious long-range magnetic ordering can be found down to 2 K. The Curie–Weiss fitting and magnetic susceptibilities under different applied fields reveal the existence of weak short-range antiferromagnetic couplings at low temperature in these systems. The calculations of isothermal magnetization exhibit a giant MCE with the maximum changes of magnetic entropy being 54.80 J/kg⋅K at 2 K for Gd3BWO9, 28.5 J/kg⋅K at 6 K for Dy3BWO9, and 29.76 J/kg⋅K at 4 K for Ho3BWO9, respectively, under a field change of 0–7 T. Especially for Gd3BWO9, the maximum value of magnetic entropy change (

−
Δ

S
M

max

) and adiabatic temperature change (

−
Δ

T

ad

max

) are 36.75 J/kg⋅K and 5.56 K for a low field change of 0–3 T, indicating a promising application for low temperature magnetic refrigeration.
Fabrication of GaAs/SiO2/Si and GaAs/Si heterointerfaces by surface-activated chemical bonding at room temperature*
Authors: Huang Rui , Lan Tian , Li Chong , Li Jing , Wang Zhiyong
Published: April 2021

The room-temperature (RT) bonding mechanisms of GaAs/SiO2/Si and GaAs/Si heterointerfaces fabricated by surface-activated bonding (SAB) are investigated using a focused ion beam (FIB) system, cross-sectional scanning transmission electron microscopy (TEM), energy dispersive x-ray spectroscopy (EDX) and scanning acoustic microscopy (SAM). According to the element distribution detected by TEM and EDX, it is found that an intermixing process occurs among different atoms at the heterointerface during the RT bonding process following the surface-activation treatment. The diffusion of atoms at the interface is enhanced by the point defects introduced by the process of surface activation. We can confirm that through the point defects, a strong heterointerface can be created at RT. The measured bonding energies of GaAs/SiO2/Si and GaAs/Si wafers are 0.7 J/m2 and 0.6 J/m2. The surface-activation process can not only remove surface oxides and generate dangling bonds, but also enhance the atomic diffusivity at the interface.
Suppression of servo error uncertainty to 10−18 level using double integrator algorithm in ion optical clock*
Authors: Yuan Jin-Bo , Cao Jian , Cui Kai-Feng , Liu Dao-Xin , Yuan Yi , Chao Si-Jia , Shu Hua-Lin , Huang Xue-Ren
Published: April 2021

A universal locking model for single ion optical clocks was built based on a simple integrator and a double integrator. Different integrator algorithm parameters have been analyzed in both numerical simulations and experiments. The frequency variation measured by the comparison of two optical clocks coincides well with the simulation results for different second integrator parameters. According to the experimental results, the sensitivity of the servo error influenced by laser frequency drift with the addition of a double integrator was suppressed by a factor of 107. In a week-long comparison of optical clocks, the relative uncertainty of the servo error is determined to be 1.9 × 10−18, which is meaningful for the systematic uncertainty of the transportable single 40Ca+ ion optical clock entering the 10−18 level.
Small activation entropy bestows high-stability of nanoconfined D-mannitol*
Authors: Cao Lin , Song Li-Jian , Cao Ya-Ru , Xu Wei , Huo Jun-Tao , Lv Yun-Zhuo , Wang Jun-Qiang
Published: April 2021

It has been a long-standing puzzling problem that some glasses exhibit higher glass transition temperatures (denoting high stability) but lower activation energy for relaxations (denoting low stability). In this paper, the relaxation kinetics of the nanoconfined D-mannitol (DM) glass was studied systematically using a high-precision and high-rate nanocalorimeter. The nanoconfined DM exhibits enhanced thermal stability compared to the free DM. For example, the critical cooling rate for glass formation decreases from 200 K/s to below 1 K/s; the T
g increases by about 20 K–50 K. The relaxation kinetics is analyzed based on the absolute reaction rate theory. It is found that, even though the activation energy E* decreases, the activation entropy S* decreases much more for the nanoconfined glass that yields a large activation free energy G* and higher thermal stability. These results suggest that the activation entropy may provide new insights in understanding the abnormal kinetics of nanoconfined glassy systems.
Deep-ultraviolet and visible dual-band photodetectors by integrating Chlorin e6 with Ga2O3
Authors: Zhao Yue , Zang Jin-Hao , Yang Xun , Chen Xue-Xia , Chen Yan-Cheng , Li Kai-Yong , Dong Lin , Shan Chong-Xin
Published: April 2021

Gallium oxide (Ga2O3) is a promising material for deep-ultraviolet (DUV) detection. In this work, Chlorin e6 (Ce6) has been integrated with Ga2O3 to achieve a DUV and visible dual-band photodetector, which can achieve multiple target information and improve the recognition rate. The photodetector shows two separate response bands at 268 nm and 456 nm. The DUV response band has a responsivity of 9.63 A/W with a full width at half maximum (FWHM) of 54.5 nm; the visible response band has a responsivity of 1.17 A/W with an FWHM of 45.3 nm. This work may provide a simple way to design and fabricate photodetectors with dual-band response.
Solar broadband metamaterial perfect absorber based on dielectric resonant structure of Ge cone array and InAs film*
Authors: Guo Kuang-Ling , Chen Hou-Hong , Huang Xiao-Ming , Hu Tian-Hui , Liu Hai-Ying
Published: April 2021

The broadband metamaterial perfect absorber has been extensively studied due to its excellent characteristics and promising application prospect. In this work a solar broadband metamaterial perfect absorber is proposed based on the structure of the germanium (Ge) cone array and the indium arsenide (InAs) dielectric film on the gold (Au) substrate. The results show that the absorption covers the whole ultraviolet-visible and near-infrared range. For the case of A > 99%, the absorption bandwidth reaches up to 1230 nm with a wavelength range varied from 200 nm to 1430 nm. The proposed absorber is able to absorb more than 98.7% of the solar energy in a solar spectrum from 200 nm to 3000 nm. The electromagnetic dipole resonance and the high-order modes of the Ge cone couple strongly to the incident optical field, which introduces a strong coupling with the solar radiation and produces an ultra-broadband absorption. The absorption spectrum can be feasibly manipulated via tuning the structural parameters, and the polarization insensitivity performance is particularly excellent. The proposed absorber can possess wide applications in active photoelectric effects, thermion modulators, and photoelectric detectors.
Simulation and experiment of the cooling effect of trapped ion by pulsed laser*
Authors: Fang Chang-Da-Ren , Huang Yao , Guan Hua , Qian Yuan , Gao Ke-Lin
Published: April 2021

We investigate the process of pulsed laser cooling using a self-constructed molecular dynamics simulation (MD-Simulation) program. We simulate the Doppler cooling process and pulsed laser Doppler cooling process of a single 40Ca+ ion, and the comparison with the experimental results shows that this self-constructed MD-Simulation program works well in the weak laser intensity situation. Furthermore, we analyze the pulsed laser Doppler cooling process of a single 27Al+ ion. This program can be used to analyze the molecular dynamic process of various situations of Doppler cooling in an ion trap, which could give predictions and experimental guidance.
Growth of high-crystallinity uniform GaAs nanowire arrays by molecular beam epitaxy*
Authors: Kang Yu-Bin , Lin Feng-Yuan , Li Ke-Xue , Tang Ji-Long , Hou Xiao-Bing , Wang Deng-Kui , Fang Xuan , Fang Dan , Wang Xin-Wei , Wei Zhi-Peng
Published: April 2021

The self-catalyzed growth of GaAs nanowires (NWs) on silicon (Si) is an effective way to achieve integration between group III–V elements and Si. High-crystallinity uniform GaAs NW arrays were grown by solid-source molecular beam epitaxy (MBE). In this paper, we describe systematic experiments which indicate that the substrate treatment is crucial to the highly crystalline and uniform growth of one-dimensional nanomaterials. The influence of natural oxidation time on the crystallinity and uniformity of GaAs NW arrays was investigated and is discussed in detail. The GaAs NW crystallinity and uniformity are maximized after 20 days of natural oxidation time. This work provides a new solution for producing high-crystallinity uniform III–V nanowire arrays on wafer-scale Si substrates. The highly crystalline uniform NW arrays are expected to be useful for NW-based optical interconnects and Si platform optoelectronic devices.
Steady and transient behavior of perylene under high pressure*
Authors: Wang Ting-Ting , Zhang Yu , Tu Hong-Yu , Han Lu , Cheng Ji-Chao , Wang Xin , Li Fang-Fei , Pan Ling-Yun , Cui Tian
Published: April 2021

Pressure can reduce the distances among atoms, thereby modifying the overall optical characteristics of molecules. In this article, the excited state behavior of perylene is carefully observed under isotropic pressure and non-complexing condition. In a steady state, absorption peak shows red shift and spectral width are broadened with pressure increasing, which is ascribed to the π-electron delocalization between molecules. In a transient state, the transition dynamics presents a wavelike tendency with pressure increasing because the shift of self-tapping exciton state is contrary to that of Y-state with pressure increasing. The results conduce to understanding the influence of inter-molecule interaction on excited state behavior with inter-molecule distance decreasing, which contributes to studying the materials under extreme condition.
Influence of constant electric field impact on the intensity and structure of the secondary luminescence of selected industrial Cannabis products
Authors: Miernik A , Juliszewski T. , Popardowski E. , Trzyniec K. , Kovalyshyn S , Wiśniowski B
Published: April 2021

The purpose of the experiments was to determine the size and structure of ultra-weak luminescence before and after the electric field. Photon emission tests were carried out in the Laboratory of Experimental Research Techniques of Raw Materials and Biological Products with PCA accreditation in the subject measurement procedure.
A robotic respiration phantom with patient data synchronization for medical tomography
Authors: Szabała T , Rymarczyk T , Vejar A
Published: April 2021

In order to benchmark on-line algorithms for electrical tomography we have designed a dynamic soft robotic phantom system. The robotic phantom will be synchronized with real-time measurements of a patient and it will support on-line tomographic algorithms during dynamic conditions. The system would allow to embody the kinematics in the tomographic inversion, for instance when using model predictive control to trigger the data acquisition at the beginning and at the end of the breathing process.
Improvement of cooling rate during cryopreservation of living cells
Authors: Nozawa M , Funaki S , Savela N
Published: April 2021

Cryopreservation is used in long term storage and transportation. Human ES / iPS cells could be useful in regenerative medicine. The problem of using cryopreservation for storing and transporting human ES / iPS cells is that the survival rate of these cells is low during the freezing and thawing process. Better cooling rates and cryoprotectants are needed for improvement of the cell survival rate. The growth of the ice crystals causes dehydration, deformation, contraction and increase of the electrolytic concentration. When cooled fast enough the cells freeze in the vitrification state and the ice crystals don’t have time to form. Immersion in liquid nitrogen is necessary to achieve a high cooling rate. To achieve a higher cooling rate than the current state, it was reported in pur previous study that the effect of the surface condition on the cooling rate during cryopreservation was investigated. It was confirmed that the cooling rate is improved by covering the cooling subject with a stainless steel mesh. However, the difference in behavior of the vapor bubble during film boiling with surface condition has not been clarified yet. In order to investigate the boiling state with high cooling rate, visualization of film boiling on the surface of cooling object was performed using a high-speed camera. It was confirmed from the image analysis results that the size and frequency of the vapor bubble were changed with the surface condition.
Investigation of cryogenic quenching of metal surfaces with various coatings
Authors: Zhang P , He D J , Xu W T
Published: April 2021

Cryogenic quenching is frequently encountered in many applications like LNG technology, cryogenic preservation of biomaterials, cryogenic material machining etc., in which one key issue is to accelerate the temperature decrease so as to achieve large cooling rate. In the present study, the cryogenic quenching experiments are conducted by immersing the metal rodlets with various coating layers at room temperature into a liquid nitrogen bath. It is found that fast cryogenic quenching of the aluminium alloy rodlet with a higher Leidenfrost temperature is achieved by coating a thin layer of nano-structure with nanopores on the outer surface. In addition, the similar method of surface fabrication is applied to the stainless steel rodlet and a moderate reduction of quenching time in liquid nitrogen is achieved. Furthermore, the cryogenic quenching of stainless steel rodlets coated with the Teflon layers is also investigated.
Minimizing the handling time in VRP with pickup-and-delivery and time windows
Authors: Amalia I S , Bakhtiar T , Jaharuddin
Published: April 2021

Improving services through goods pickups and deliveries to expand the market is currently being carried out by many companies. This effort needs another step of optimization to avoid losses due to additional resources, such as time, which must be held by the company. In the case of simultaneous goods pickups and deliveries using a vehicle with single transport access, the policy of arranging goods in the vehicle can affect the length of time for service. Single transport access causes goods that want to be unloaded obstructed by the other goods, thus requires additional time for handling. In this paper, the problem of a vehicle’s route and handling time in picking and delivering goods with time windows is modeled as the Traveling Salesman Problem. The objective function of this problem is to minimize the total travel time and handling time during the picking and delivering goods. The model is implemented in the case of bicycle pickup and delivery services involving 15 bicycle shops. The capacity of the vehicle is 15 units of bicycle. In this case, a solution consisting the pickup and delivery route and optimal goods order is obtained with an objective function value of 334 minutes.
Lecturer Teaching Scheduling that Minimize The Difference of Total Teaching Load Using Goal Programming
Authors: Hasanah Alfiyyah , Hanum Farida , Ruhiyat
Published: April 2021

An implementation of scheduling problems is the scheduling of lecturers in educational institution. There are several considerations, including the availability of teaching time, the suitability between the subject and the lecturer’s field, and also the fairness of assignments for each lecturer. Because of these considerations, scheduling using operation research is needed to overcome the weaknesses of scheduling by conventional methods, which may not be able to cover several rules and conditions that need to be met. This scheduling problem can be solved by linear goal programming. In this work, two types of constraints need to be considered, i.e. hard and soft constraints. The hard constraints are some constraints that must be fulfilled, while the soft constraints are some constraints that hoped to be fulfilled as much as possible. In goal programming, the goal is minimizing the deviation variable, which may be able to make the soft constraints deviate from the expected value. This scheduling model is applied to the data of scheduling lecturers in the Department of Mathematics XYZ University. In this model, the main goal is minimizing the difference of total teaching load and it was achieved quite well because the total credits earned by each lecturer was quite same due to the limitation of deviation value. However, it makes the other goal wasn’t fulfilled, there are several lecturers who get schedules to teach courses outside their division.
An Evacuation Route In Bengkulu City Based On Fuzzy Dijkstra Algorithm
Authors: Afandi N , Mayasari Z M
Published: April 2021

Bengkulu City is one area that has the potential to be hit by the tsunami disaster. Therefore an evacuation route is needed that can be used when a disaster strikes. In this study, a weighted graph is made by considering the node as a road intersection, the edge as the road connecting it, and weight as a fuzzy output obtained based on the length and width of the road. Furthermore, the evacuation route is obtained by calculating the smallest number of weights from each intersection to the cluster point using Dijkstra Algorithm. The result is an evacuation route that consider the length and width of the roads.
Vertical evacuation planning to reduce a risk of a tsunami disaster in teluk segara district, bengkulu city
Authors: Mayasari Zulfia Memi , Astuti Mulia , Afandi Nur , Fauzi Yulian
Published: April 2021

Bengkulu Province is classified as a province that is very prone to earthquakes and tsunamis. In order to minimize the impact of the tsunami hazard, preparedness to mitigate the tsunami hazard is needed. One of the ways is by providing information about the optimal evacuation route, assembly points and evacuation shelter buildings (ESB) and ESB capacity. The purpose of this study is to obtain an optimal evacuation route model to minimize the impact of the tsunami hazard in Teluk Segara District, Bengkulu City. The determination of the minimum evacuation route using the Floyd Warshall algorithm based on the minimum time of evacuation. In determining the minimum evacuation time, several factors are considered i.e. road width, road density, road capacity, walking speed of evacuees and group walking speed. This research produces the horizontal and vertical tsunami evacuation routes equipped with ESB capacities.
Clustering Regions Based on Socio-Economic Factors Which Affected the Number of COVID-19 Cases in Java Island
Authors: Rahardiantoro Septian , Sakamoto Wataru
Published: April 2021

Around 60% of COVID-19 positive cases in Indonesia have occurred in Java Island. This study provides clustering adjacent regions (cities and regencies) in Java Island into some groups based on some socio-economic factors that are suspected to affect the COVID-19 infection rates (positive cases per 100,000 residents), which could be useful for decision making by government. The factors involved in this study are poverty percentage, Human Development Index (HDI), average of expenditure per month, and open unemployment rate. There are two steps in our data analysis: first, we determined the factors that affected the infection rate significantly by using lasso, and then we estimated region-specific effects of each significant factor by using generalized lasso. In the generalized lasso, two types of spatial structure were considered, namely, regions divided by province, and neighbourhood regions based on k-means clustering and Voronoi tessellation. The tuning parameter in both lasso and generalized lasso was selected by 5-folds cross-validation. Based on the first step, three variables were found to affect the infection rate significantly. Then in the second step, the three variables had spatially varying coefficients in the generalized lasso using regions divided by provinces. On the other hand, HDI provided spatially varying coefficient in the generalized lasso using region based on k-means clustering and Voronoi tessellation.
Clustering Provinces in Indonesia Based on Daily Covid-19 Cases
Authors: Fransiska H
Published: April 2021

The latest form of coronavirus is Coronavirus Disease 2019 (Covid-19). It was discovered in Wuhan, Hubei Province, China. The Covid-19 virus is growing very rapidly. Starting from Wuhan which then spread to the surrounding provinces to all provinces in China, and even spread to other countries such as Indonesia. Until August 17, 2020, an update from the KEMENKES RI that the development of Covid-19 in 34 Indonesian Provinces was positive ( 141,370), recovered (94,458), and died (6,207). This means that the case fatality rate in Indonesia is 4.39%. As a disease that is currently becoming a pandemic has a major impact in all sectors, it is very important to explore data and carry out clustering that is useful for policy making for the government such as decision making on WFH, PSBB, New Normal, or lockdown. The clustering provinces based on those similarities (homogeneity) data to find out which provinces have Covid-19 cases with similar characteristics and between clusters have different characteristics. Clusterization is expected to inform areas of high, medium, and low risk and their characteristic characteristics. Based on Covid-19 data, we used the hierarchical clustering method shows there are 4 clusters: cluster 1 (Jakarta and East Java), cluster 2 (Central Java, West Java, and South Sulawesi), cluster 3 (South Kalimantan, North Sumatra, South Sumatra, Papua, Bali, and East Kalimantan), and the provinces others in cluster 4. Validation of clustering shows Dynamic Time Warping (DTW) distance for hierarchical clustering (average linkage) is a good classification with an average silhouette value of 0.70.
Long Short-Term Memory Neural Network Model for Time Series Forecasting: Case Study of Forecasting IHSG during Covid-19 Outbreak
Authors: Andhika Viadinugroho Raden Aurelius , Rosadi Dedi
Published: April 2021

Long Short-Term Memory (LSTM) is one of the developments from Recurrent Neural Network (RNN) architecture. In this paper, we use LSTM architecture for modeling and forecasting the Indonesian Composite Stock Price Index (IHSG) closing value data. We also compare the performance of the LSTM method with the ARIMA and the Radial Basis Function (RBF) Neural Network method. In the implementation, we use both R and Python open source software. For empirical study we use the data from January until August 2020 to see the performance of the considered methods during Covid-19 pandemic periods of time. From the analysis, we found that LSTM performs better than ARIMA, but outperformed by RBF for this data.
Human Mobility Patterns and Its Cross-Correlation with the COVID-19 Transmission in Jakarta, Indonesia
Authors: Wijayanto Arie Wahyu , Wulansari Ika Yuni
Published: April 2021

The novel coronavirus disease (COVID-19) has been rapidly spreading and causing a severe health crisis in Indonesia. In the absence of medically proven vaccines, official authorities commonly adopt a social control approach under the strict public order. The Indonesian Government is no different, which imposed a large scale social restriction as an intervention strategy in Jakarta and other major cities. In this paper, we aim to quantify the correlation between human mobility and the daily new cases of COVID-19 which are further divided into two main distinct patterns: weekdays and weekends. We utilized the big data sources presented by reputable online service providers include Apple, Waze, and Google in terms of the reported daily mobility patterns. The mobility patterns include driving and walking activities as well as the movement trends across different public places such as retail and recreation, pharmacies, groceries, parks, etc from March 1 to July 31, 2020. To capture the real growth rate of COVID-19, we use the official data reported by Governmental Disease Response Acceleration Task Force. Our cross-correlation analysis revealed that in Jakarta (province-level) and Indonesia (country-level), the COVID-19 case daily growth rate is correlated with the human mobility patterns of driving and walking activities on both weekends and weekdays time. Our work put the additional insight in supporting the importance of social distancing as an effective mitigation strategy to combat the coronavirus outbreak.
Swing Voters’ Vote Choice Prediction Using Multilevel Logit Model to Improve Election Survey Accuracy
Authors: Irvani D , Sadik K , Kurnia A , Saefuddin A , Erfiani
Published: April 2021

Public opinion surveys are often used to predict an election result. However, the predictions are not always accurate due to many factors. The presence of swing voters at the time of survey is one of the sources of the inaccuracy. On the other hand, election surveys are also often conducted by using multi-stage random sampling method so that ordinary models such as logit model generally do not provide satisfactory results. The data, hence, is complex and may be approached by multilevel models. The study is conducted to assess the extent to which a prediction of swing voters’ vote choice through a multilevel logit model can improve survey accuracy. The data used in this study was the result of a survey conducted using stratified multistage random sampling method two weeks before the 2019 presidential election. The model with 15 predictors and random effects for villages and neighborhood providing 96.3% accuracy and AUC reached 99.1% in the validation process. Based on the final model, the swing voters in this survey were predicted to vote more for Candidate B (10.4%) than Candidate A (7.5%). The direction of the swing voters’ support different from the loyal voters who prefer Candidate A (49.1%) than Candidate B (33.0%). The prediction of swing voters’ vote choice using multilevel logit model significantly improved the survey accuracy. Before the swing voters’ support was predicted the absolute deviation between the survey result and the election result was quite large, around 6.4%-11.5%. After swing voters’ support was predicted the absolute difference shrank to 1.1%.
A Study of ZIP and ZINB Regression Modeling for Count Data with Excess Zeros
Authors: Amalia R N , Sadik K , Notodiputro K A
Published: April 2021

Count data with excess number of zeros can cause overdispersion problems. Overdispersion is the presence of greater variability in a data set than would be expected. Overdispersion due to zero-inflated data can be handled either by Zero-inflated Poisson (ZIP) regression or Zero-inflated Negative Binomial (ZINB) regression. In this paper, the performances of different models have been compared based on their MSE, RMSE, bias, and AIC using simulation. The simulated data were generated using ZIP and ZINB distributions. The data were generated using a combination of observation size (n), mean (µ), and the proportion of zeros observation (ω) were imposed to facilitate comparison. To ensure the present of overdispersion, the score test has been applied to the generated data. As expected, the results showed that ZIP and ZINB regression performed better when compared to the Poisson regression. Moreover, in general the simulation results showed that ZINB regression showed better performance than ZIP and Poisson regressions. In this paper, ZINB regression was applied to analyze maternal mortality rate in East Java. The results showed that maternal mortality was significantly affected by the percentage of pregnant woman visiting the clinics for the first time as well as by the percentage of pregnant woman visiting clinics for the fourth time.
Application of Logistic Regression to Determine The Quality of Foreign Tourists to Indonesia
Authors: Agustina Neli , Puspita Chaterina D. , Arifatin Dini , Yordani Ricky
Published: April 2021

Tourism has become a priority sector in the development of the Indonesian economy. Tourism is expected to be a prime mover in accelerating economic growth in Indonesia through job creation and business opportunities, foreign exchange earnings, and infrastructure development. The role of tourism in the Indonesian economy is increasing, in 2018 the contribution of the tourism sector to GDP reached $16.426 million. In terms of quantity, the number of foreign tourists visiting Indonesia in the past five years shows a rising trend. The number of foreign tourists visiting 2018 reached 15.81 million visits, up 12.61 percent compared to the number of visits during 2017. In terms of the quality of foreign tourists, the average expenditure of foreign tourists during the last five years per visit while in Indonesia shows an increasing trend, but growth is still relatively small. This study aims to analyze the determinants in improving the quality of foreign tourists in supporting the tourism sector as the main driver in accelerating economic growth. By using logistic regression analysis, the results show that foreign tourists with the purpose of business visits is 1.41 times greater odds to spend their expenses above the average expenditure than with the purpose of personal visits. Furthermore, based on their nationality, foreign tourists who come from ASEAN continent have greater odds to spend their expenses above the average than the tourist who come from Asia (exclude ASEAN) and Non-Asia countries.
Churn Analysis in Telecommunication Industry Customers Using Semiparametric and Non Parametric Survival Method
Authors: Monika Ade Vreyyuning , Indahwati  , Aidi Muhammad Nur
Published: April 2021

One of the challenges faced by Customer Relationship Management (CRM) of Telecommunication Company is customer retention efforts. The success rate of customer retention can be seen by the customer switching or churn process. Using the background and usage data related to the loyalty of the customers, it can be known the probability that customers will churn at a certain time. To overcome the problem, survival analysis will be carried out with parametric model using Cox Proportional Hazard and non-parametric using Support Vector Machine (SVM) for customer data. The data used in this study are customer data from telecommunication company who subscribe bundling package Internet and IPTV which are taken from 1000 customers in the Jabodetabek area. The time a customer is registered for the first time is defined as the start time and the last observation date is the end time. During the observation period, customer churn time is recorded. Based on the Kaplan Meier curve and log rank test, it is shows that there is a significant difference curve between customers with six different age categories. The results of the analysis found that SVM survival is able to compensate for Cox Proportional Hazard. Based on the result of the concordance index, the performance of the SVM survival has a better performance than Cox Proportional Hazard. One possibility that survival of SVM give a better performance is because the assumption of Cox Proportional Hazard is not met.