bluuebunny/crossref_metadata_2025 huggingface dataset:
Existence and instability of normalized standing waves for the fractional Schrödinger equations in the L2-supercritical case
Authors: Feng Binhua , Ren Jiajia , Wang Qingxuan
Published: July 2020

In this paper, we study the existence and instability of normalized standing waves for the fractional Schrödinger equation i∂tψ = (−Δ)sψ − f(ψ), where 0 < s < 1, f(ψ) = |ψ|pψ with 4sN<p<4sN−2s or f(ψ) = (|x|−γ*|ψ|2)ψ with 2s < γ < min{N, 4s}. To do this, we consider normalized solutions of the associated stationary equation (−Δ)su + ωu − f(u) = 0. By constructing a suitable submanifold of a L2-sphere and considering an equivalent minimizing problem, we prove the existence of normalized solutions. In particular, based on this equivalent minimizing problem, we can easily obtain the sharp threshold of global existence and blow-up for the time-dependent equation. Moreover, we can show that all normalized ground state standing waves are strongly unstable by blow-up. Our results are a complementary to the results of Peng and Shi [J. Math. Phys. 59, 011508 (2018)] and Zhang and Zhu [J. Dyn. Differ. Equations 29, 1017–1030 (2017)], where the existence and stability of normalized standing waves have been studied in the L2-subcritical case.
Measurement of elastic moduli and internal frictions using modified piezoelectric ultrasonic composite oscillator technique with large frequency mismatch
Authors: Xie Mingyu , Li Faxin
Published: July 2020

In this Note, first, the calculation errors of elastic moduli and internal frictions using the explicit formulas in the traditional and modified piezoelectric ultrasonic composite oscillator technique (PUCOT and M-PUCOT) are comparatively studied when the frequency match condition is not satisfied. Then, new implicit formulas free of frequency match are proposed for the three-component M-PUCOT. Finally, the measurement results on a lead zirconate titanate ferroelectric ceramic from room temperature to 500 °C by using the pervious explicit formulas and the new implicit formulas are compared. The results show that when the frequency mismatch is within 15%, the induced error by using the explicit formulas is less than 0.5% and 2.5% for moduli and internal frictions, respectively. When the frequency mismatch is over 15%, the implicit formulas are suggested to improve the accuracy of M-PUCOT.
A fiber scanning tunneling microscope for optical analysis at the nanoscale
Authors: Jakob René , Nilius Niklas
Published: July 2020

A hybrid scanning tunneling/optical near-field microscope is presented, in which an optical fiber tip coated with 100 nm thick Ag/Cr films scans the surface. The tip metallization enables operating the instrument via a current-based distance control and guarantees sub-nanometer spatial resolution in the topographic channel. The fiber tip simultaneously serves as nanoscale light source, given the optical transparency of the metal coating. The emission response of the tip–sample junction is collected with two parabolic mirrors and probed with a far-field detector. To test the capabilities of the new setup, the evolution of the optical signal is monitored when the tip approaches a gold surface. The intensity rise and frequency shift of the emission provide evidence for the development of coupled plasmon modes in the tip–sample cavity. Photon mapping is employed to probe the optical inhomogeneity of Ru(0001) and TiO2(110) surfaces covered with silver deposits. While the 2D Ag flakes on Ru give rise to a near-field enhancement, the 3D particles on titania locally damp the gap plasmons and lower the emitted intensity. The lateral resolution in the optical channel has been estimated to be ∼1 nm, and optical and topographic signals are well correlated. Our fiber microscope thus appears to be suitable for probing optical surface properties at the nanoscale.
Spin wave generation via localized spin–orbit torque in an antiferromagnet-topological insulator heterostructure
Authors: Xu Xinyi , Semenov Yuriy G. , Kim Ki Wook
Published: July 2020

The spin–orbit torque induced by a topological insulator (TI) is theoretically examined for spin wave generation in a neighboring antiferromagnetic thin film. The investigation is based on the micromagnetic simulation of Néel vector dynamics and the analysis of transport properties in the TI. The results clearly illustrate that propagating spin waves can be achieved in the antiferromagnetic thin-film strip through localized excitation, traveling over a long distance. The oscillation amplitude gradually decays due to the non-zero damping as the Néel vector precesses around the magnetic easy axis with a fixed frequency. The frequency is also found to be tunable via the strength of the driving electrical current density. While both the bulk and the surface states of the TI contribute to induce the effective torque, the calculation indicates that the surface current plays a dominant role over the bulk counterpart except in the heavily degenerate cases. Compared to the more commonly applied heavy metals, the use of a TI can substantially reduce the threshold current density to overcome the magnetic anisotropy, making it an efficient choice for spin wave generation. The Néel vector dynamics in the nano-oscillator geometry are examined as well.
Dense high-energy
γ
-rays emission by ultra-intense laser interacting with a concave target
Authors: Zhao Yuan , Liu Jianxun , Xia Guoxing , Bonatto Alexandre
Published: July 2020

We propose to use a 10 petawatt (PW) laser irradiating onto a target with a concave surface, which can focus the laser beam and attain a more intense laser field, so as to increase both the yield and mean energy of emitted γ-rays. 2D particle-in-cell simulation results show that the peak electric field after the reflection of the laser from the target in this new scheme can reach ∼1.8 times as high as that in the plane target case. Such an enhanced laser field enables an increase in the number of hot electrons in front of the incident plane and raises the probability rate of generating high-energy γ-rays significantly by non-linear Compton scattering. As a result, 1.5×1013 γ photons with a mean energy of 9.2 MeV are obtained. These photons mainly point toward two directions and distribute in pulses with the duration of each pulse of ∼400 as. A brightness as high as 3.6×1025 photons/(mm2mrad2s0.1%BW) is obtained in one pulse. Compared to no positron observed for a plane target, a positron yield of 3.0×108 can be achieved in this new scheme.
Symmetry breaking in the Stark Control of Electrons at Interfaces (SCELI)
Authors: Garzón-Ramírez Antonio J. , Franco Ignacio
Published: July 2020

Ultrafast control of electron dynamics is essential for future innovations in nanoelectronics, catalysis, and molecular imaging. Recently, we developed a general scheme (Stark Control of Electrons at Interfaces or SCELI) to control electron dynamics at interfaces [A. J. Garzón-Ramírez and I. Franco, Phys. Rev. B 98, 121305 (2018)] that is based on using few-cycle lasers to open quantum tunneling channels for interfacial electron transfer. SCELI uses the Stark effect induced by non-resonant light to create transient resonances between a donor level in material B and an acceptor level in material A, resulting in B → A electron transfer. Here, we show how SCELI can be employed to generate net charge transport in ABA heterojunctions without applying a bias voltage, a phenomenon known as laser-induced symmetry breaking. The magnitude and sign of such transport can be controlled by simply varying the time asymmetry of the laser pulse through manipulation of laser phases. In particular, we contrast symmetry breaking effects introduced by manipulation of the carrier envelope phase with those introduced by relative phase control in ω + 2ω laser pulses. The ω + 2ω pulse is seen to be far superior as such pulses exhibit a larger difference in field intensity for positive and negative amplitudes. The results exemplify the power of Stark-based strategies for controlling electrons using lasers.
Combining phonon accuracy with high transferability in Gaussian approximation potential models
Authors: George Janine , Hautier Geoffroy , Bartók Albert P. , Csányi Gábor , Deringer Volker L.
Published: July 2020

Machine learning driven interatomic potentials, including Gaussian approximation potential (GAP) models, are emerging tools for atomistic simulations. Here, we address the methodological question of how one can fit GAP models that accurately predict vibrational properties in specific regions of configuration space while retaining flexibility and transferability to others. We use an adaptive regularization of the GAP fit that scales with the absolute force magnitude on any given atom, thereby exploring the Bayesian interpretation of GAP regularization as an “expected error” and its impact on the prediction of physical properties for a material of interest. The approach enables excellent predictions of phonon modes (to within 0.1 THz–0.2 THz) for structurally diverse silicon allotropes, and it can be coupled with existing fitting databases for high transferability across different regions of configuration space, which we demonstrate for liquid and amorphous silicon. These findings and workflows are expected to be useful for GAP-driven materials modeling more generally.
Bromination effect of polybrominated diphenyl ethers on the graphyne surface on enhanced adsorption characteristics using density functional theory study
Authors: Kim Taeyoon , Kwon Yongju , Kwon Soonchul
Published: July 2020

Among various techniques for treating polybrominated diphenyl ethers (PBDEs), adsorption and removal methods using carbon materials are widely applied to remove and decompose organic pollutants with high efficiency. Of many carbon allotropes, theoretically developed graphyne has numerous promising applicabilities for its strong carbon chemical bond, large conjugate system, good chemical stability, and excellent electrical conductivity. To evaluate the PBDE removal capability of graphyne as an adsorbent, we investigated the adsorption properties of ten PBDE species on graphyne using the density functional theory calculation. Furthermore, we analyzed the correlation between the hydrophobicity and adsorption characteristics of PBDEs and found that the adsorption energy increased with the hydrophobicity and the bromination number, indicating a linear relationship for only seven samples. In BDE154, BDE183, and BDE209, however, this linearity was not clearly found because when the bromine groups of the PBDE structures were located at 6,6′, two phenyl rings repelled each other to limit adsorption. From a water solvation model, graphyne also indicated a high adsorption capacity of PBDEs. It is worth noting that graphyne is considered to be a suitable material for PBDE adsorption, and the adsorption reaction may vary depending on the structural characteristics and hydrophobicity of the PBDEs.
Salt induced programmed cell death in rice: evidence from chloroplast proteome signature
Authors: Ambastha Vivek , Sopory Sudhir K. , Tripathy Baishnab C. , Tiwari Budhi Sagar
Published: July 2020

Soil salinity, depending on its intensity, drives a challenged plant either to death, or survival with compromised productivity. On exposure to moderate salinity, plants can often survive by sacrificing some of their cells ‘in target’ following a route called programmed cell death (PCD). In animals, PCD has been well characterised, and involvement of mitochondria in the execution of PCD events has been unequivocally proven. In plants, mechanistic details of the process are still in grey area. Previously, we have shown that in green tissues of rice, for salt induced PCD to occur, the presence of active chloroplasts and light are equally important. In the present work, we have characterised the chloroplast proteome in rice seedlings at 12 and 24 h after salt exposure and before the time point where the signature of PCD was observed. We identified almost 100 proteins from chloroplasts, which were divided in to 11 categories based on the biological functions in which they were involved. Our results concerning the differential expression of chloroplastic proteins revealed involvement of some novel candidates. Moreover, we observed maximum phosphorylation pattern of chloroplastic proteins at an early time point (12 h) of salt exposure.
Crop residue ashes reduce leaching, persistence and bioavailability of sulfosulfuron and pretilachlor used in the succeeding crop
Authors: Kumar Anup , Singh Neera
Published: July 2020

Ash produced during burning of crop biomass may affect the behaviour of herbicides applied in the crops sown after burning. Therefore, the effect of wheat straw ash (WSA) on pretilachlor and rice straw ash (RSA) on sulfosulfuron leaching, degradation and bioactivity in soils was studied. Both ash types reduced downward mobility of respective herbicides, but the effect varied with soil type and dose of ash. Effect was greater in the sandy loam soil because masking of ash was observed in the clay loam soil. Pretilachlor degradation studies indicated that the WSA enhanced degradation and effect was greater in the flooded soil where 0.2% ash reduced the half-life (t1/2) by nearly half, whereas increasing the ash content to 0.5% slightly increased the t1/2 values. The effect of RSA on sulfosulfuron degradation was significant in the sandy loam soil. A pot culture study in wheat also confirmed these results. The effect of the WSA on the bioavailability of sulfosulfuron was assayed by observing its effect on mustard seedlings and results suggested that even 0.1% WSA reduced herbicide availability. Burning of crop residues on field is a major concern due to air pollution, but also affects the fate of soil-applied herbicides. Our study has implications in assaying the role of crop ashes on pesticide fate in soils where crop residues are burned regularly.
Understanding Australia’s national feral cat control effort
Authors: Garrard Georgia E. , Kusmanoff Alexander M. , Faulkner Richard , Samarasekara Chathuri L. , Gordon Ascelin , Johnstone Alice , Peterson Isaac R. , Torabi Nooshin , Wang Yan , Bekessy Sarah A.
Published: July 2020

Abstract
Context. Feral cats (Felis catus) pose a significant threat to Australia’s native species and feral cat control is, therefore, an important component of threatened species management and policy. Australia’s Threatened Species Strategy articulates defined targets for feral cat control. Yet, currently, little is known about who is engaged in feral cat control in Australia, what motivates them, and at what rate they are removing feral cats from the environment.
Aims. We aim to document who is engaging in feral cat control in Australia, how many cats they remove and to estimate the number of feral cats killed in a single year. Furthermore, we seek to better understand attitudes towards feral cat control in Australia.
Methods. We used a mixed methods approach combining quantitative and qualitative techniques. Feral cat control data were obtained from existing data repositories and via surveys targeting relevant organisations and individuals. A bounded national estimate of the number of feral cats killed was produced by combining estimates obtained from data repositories and surveys with modelled predictions for key audience segments. Attitudes towards feral cat control were assessed by exploring qualitative responses to relevant survey questions.
Key results. We received information on feral cat control from three central repositories, 134 organisations and 2618 individuals, together removing more than 35000 feral cats per year. When including projections to national populations of key groups, the estimated number of feral cats removed from the environment in the 2017–2018 financial year was 316030 (95% CI: 297742–334318).
Conclusions. Individuals and organisations make a significant, and largely unrecorded, contribution to feral cat control. Among individuals, there is a strong awareness of the impact of feral cats on Australia’s biodiversity. Opposition to feral cat control focussed largely on ethical concerns and doubts about its efficacy.
Implications. There is significant interest in, and commitment to, feral cat control among some groups of Australian society, beyond the traditional conservation community. Yet more information is needed about control methods and their effectiveness to better understand how these efforts are linked to threatened species outcomes.
Linear resistivity and Sachdev-Ye-Kitaev (SYK) spin liquid behavior in a quantum critical metal with spin-1/2 fermions
Authors: Cha Peter , Wentzell Nils , Parcollet Olivier , Georges Antoine , Kim Eun-Ah
Published: July 2020

Significance

In “Planckian metals,” electrons dissipate energy at the fastest possible rate allowed by the fundamental laws of quantum mechanics, resulting in a linear temperature dependence of their electrical resistivity. Although observed for a number of quantum materials, this phenomenon lacks a general theoretical understanding and is often considered as one of the prominent fundamental questions in condensed matter physics. Here, we show that Planckian dissipation and a behavior consistent with the “marginal Fermi liquid” phenomenology emerge in the quantum critical regime separating a Mott insulating spin glass and a Fermi liquid. By establishing this behavior in an explicit model solvable by state-of-the-art computational methods, our theory paves the way toward a deeper understanding of Planckian or “strange” metals.
No clear association emerges between intergenerational relationships and COVID-19 fatality rates from macro-level analyses
Authors: Arpino Bruno , Bordone Valeria , Pasqualini Marta
Published: July 2020

Significance

Several factors have been examined that contribute to the unequal impact of coronavirus disease 2019 (COVID-19) in terms of lethality and prevalence of cases across different geographical areas. Among them, intergenerational relationships (e.g., coresidence and contacts between family members of different generations) have been suspected to play a role in the spread and lethality of COVID-19. Our results show that available evidence on the link between intergenerational relationships and COVID-19 is inconclusive. Future studies need to use individual-level data to obtain more robust statistical evidence on this link before any policy suggestion can be provided.
LncRNA NEAT1 regulated inflammation and apoptosis in a rat model of sepsis-induced acute kidney injury via MiR-27a-3p/TAB3 axis
Authors: Wang Jiasheng , Chen Yong , Tang Ze , Hu Dabi , Yao Caoyuan , Yang Lei
Published: July 2020

This study explored the mechanism of NEAT1 in sepsis-induced AKI rats. Cecal ligation punctures (CLP)-induced AKI rats were injected with siRNA-NEAT1 lentivirus. Kidney histopathology and apoptosis were evaluated via hematoxylin-eosin and TUNEL staining, respectively. ELISA determined the levels of Blood urea nitrogen (BUN), serum creatinine (SCr), neutrophil gelatinase-associated lipocalin (NGAL), kidney injury molecule-1 (KIM-1), TNF-α, Interleukin (IL)-1β, and IL-6. Colorimetry measured malondialdehyde (MDA), superoxide dismutase (SOD) activities. qPCR analyzed NEAT1, miR-27a-3p, TAB3, Bcl-2, and Bax expressions. siNEAT1 reversed the promotive effect of CLP on kidney histopathological injury, and BUN, SCr, NGAL, KIM-1, TNF-α, IL-1β, IL-6, MDA, and Bax levels and apoptosis, but raised CLP-downregulated SOD and Bcl-2 levels. NEAT1 sponged miR-27a-3p which targeted TAB3. siNEAT1 upregulated miR-27a-3p and downregulated TAB3 expression. TAB3 overexpression reversed the inhibitory effect of siNEAT1 on the LPS-induced apoptosis of HK-2 cells. siNEAT1 alleviated sepsis-induced AKI in rats and LPS-induced sepsis of cells via miR-27a-3p/TAB3 axis.
Efficiency enhancement in InGaN-based laser diodes using an optimized Al0.12Ga0.88N electron blocking layer
Authors: Sandhu Harmanpreet Kaur , Sharma Abhishek , Jain Alok , Das Samaresh
Published: July 2020

In this paper, a design for an electron blocking layer (EBL) is proposed to enhance the wall plug efficiency of InGaN-based laser diodes. Using calibrated 3D simulations (including thermal models), a comprehensive analysis of various design aspects (composition, thickness and p-doping) of EBLs is conducted, including their impact on carrier (electron and hole) wavefunction overlap and stimulated recombination rate in the quantum wells (QWs) along with the space charge density, electric field and free carrier absorption (FCA) at the interface of the p-side waveguide/EBL. The results indicate that Poole–Frenkel emission is vital for consideration of FCA in the p-doped layers of the epitaxial structure. Consequently, the proposed EBL design reduces electron overflow, improves hole injection, decreases the internal absorption losses and thus, enhances the internal quantum efficiency of the device. The threshold current is reduced from 230 mA to 205 mA as compared to the reference structure. The hole barrier is reduced by 23.93%. Hence, the output power is increased from 1.746 W to 1.95 W, and the voltage drop as well as the device temperature is reduced. These improvements enhance the efficiency from 37.4% of the reference structure to 42.1% in the proposed structure (corresponding to a bias current of 1 A).
Classical Hamiltonian time crystals–general theory and simple examples
Authors: Dai Jin , Niemi Antti J , Peng Xubiao
Published: July 2020

We focus on a Hamiltonian system with a continuous symmetry, and dynamics that takes place on a presymplectic manifold. We explain how the symmetry can become spontaneously broken by a time crystal, that we define as the minimum of the available mechanical free energy that is simultaneously a time dependent solution of Hamilton’s equation. The mathematical description of such a timecrystalline spontaneous symmetry breaking builds on concepts of equivariant Morse theory in the space of Hamiltonian flows. As an example we analyze a general family of timecrystalline Hamiltonians that is designed to model polygonal, piecewise linear closed strings. The vertices correspond to the locations of pointlike interaction centers; the string is akin a chain of atoms, that are joined together by covalent bonds, modeled by the links of the string. We argue that the timecrystalline character of the string can be affected by its topology. For this we show that a knotty string is usually more timecrystalline than a string with no self-entanglement. We also reveal a relation between phase space topology and the occurrence of timecrystalline dynamics. For this we show that in the case of three point particles, the presence of a time crystal can relate to a Dirac monopole that resides in the phase space. Our results propose that physical examples of Hamiltonian time crystals can be realized in terms of closed, knotted molecular rings.
Synthesis of Al-doped zinc oxide nano particle TCO material by simple Sol-Gel method
Authors: Roy Dhananjoy , Basu M , Paul S
Published: July 2020

Transparent Conducting Oxides (TCOs) are thin films of optically transparent and electrically conductive material. They are an important component in a number of electronic devices including liquid-crystal displays, OLEDs, touchscreens and photovoltaics etc. Indium tin oxide (ITO) is the most widely used TCO but its toxic effect and scarcity in nature causes for high cost of the product and hence technology needs a suitable replacement of it. Out of few replaceable materials, Aluminum doped Zinc Oxide (AZO) semiconductive material has been proven its potential replaceability due to its good transparency in the visible light as well as good conductivity. Also Zinc Oxide is abundant in nature and has no toxic effect. Pure ZnO and AZO sample were synthesized by simple low cost sol gel method and characterized optically and electrically. Effects of Al doping into ZnO nano crystal has been studied on transparency and conductivity aspects. It is observed that in both cases there is an optimum Al atoms concentration governed by the defects introduced by interstitial Al atoms in AZO nano crystal.
Design of a Circular-Slot Multiband (UWB) Antenna with Non-Periodic DGS for WLAN/WiMAX Applications
Authors: Thakur Sunil , Singh Navdeep
Published: July 2020

The paper discusses bandwidth enhancement of a microstrip patch antenna. It explores the application of DGS with parasitic elements to obtain a compact UWB multiband antenna. The antenna is designed on a 14*25 mm2 RT-Duroid (5880) substrate. A comparison is made between four antenna designs with the same dielectric substrate. The antenna design with circular slot on the patch, facilitated with the shorting pins, shows bandwidth enhancement. It uses non-periodic Defective Ground Structure (DGS) for improvement in return loss characteristics, bandwidth enhancement and multiband operation. The slot on the patch provides compact size and DGS gives wide bandwidth (80.5%) with five resonant frequencies of 0.92 GHz, 2.36 GHz, 3.46 GHz, 4.98 GHz & 7.9 GHz making it applicable for GSM (890-966 MHz), WLAN/WiMAX (2.4/3.6/4.9), multi-band applications.
Atomistic simulations of precipitation hardening mechanisms in Mg-Al alloys
Authors: Moitra Amitava
Published: July 2020

Precipitation hardening of Mg-Al alloys primarily comes from the interaction of basal dislocations with Mg17Al12 precipitates. Strengthening of Mg-alloys by precipitation is much less efficient than in other metallic alloys (e.g. Al) and this behaviour has been attributed to geometrical efects, as the Mg17Al12 precipitates grow as thin plates/lozenses or long rod shape parallel to the basal plane. In the present study I focus on the dislocation/precipitate interaction in the athermal limit for both edge and screw type basal dislocations, carried out using molecular statics methodology. In particular, the critical resolved shear stress (CRSS) necessary to overcome the precipitates are determined as a function of the precipitate size and compared with predictions of classical continuum models. These results provide valuable information about the precipitate hardening mechanisms and suggested new avenues to improve the mechanical properties of Mg-Al alloys.
Atom localization in cascade type system
Authors: Mal Kalan , Mondal Suman , Bhattacharyya Dipankar , Bandyopadhyay Amitava
Published: July 2020

A three-level cascade type system is subjected to a standing wave (SW) field acting between the ground energy level and the intermediate energy level of the system and the probe field scans the uppermost energy level from the intermediate energy level. Optical Bloch equations (OBE) for this three-level system are derived from the Liouville equation (Master equation) where the decay terms are added phenomenologically. These OBEs are solved analytically under steady state condition by using weak probe approximation. Under doppler free condition precession of localization was controlled by tuning the SW rabi frequency and relative orientation of the applied fields.
A driven ferromagnetic chain with binary hopping as an efficient spin polarizer
Authors: Sarkar Manik , Dey Moumita , Maiti Santanu K.
Published: July 2020

Spectral properties of a magnetic chain and spin dependent electron transport through it are critically examined in presence of light irradiation. Two different kinds of bonds, long and short are taken into account where each site of the chain is composed of a finite magnetic moment which yields spin dependent scattering to generate polarized currents from a unpolarized one. The degree of spin polarization and its phase can selectively be adjusted with the help of irradiation parameters. All the results are valid for a wide range of physical parameters which suggest that the present proposal can be verified through a suitable laboratory experiment.
Simple, Efficient and Economically Viable Techniques for temperature dependant Thermopower data acquisition of Thermoelectric materials
Authors: Mahakal S , Das Diptasikha , Jana A , Banerjee Aritra , Malik K
Published: July 2020

A simple, economically viable and precise thermopower measurement techniques have been presented in this paper. Continuous data acquisition and simultaneous control of the instruments are achieved by using LabVIEW software. Set-up is built to measure thermopower of the low temperature thermoelectric material down to 10K. A LabVIEW program is developed to collect thermopower data of few μV/K to few hundred μV/K. Thermal stabilization and simple calculations are incorporated to avoid the spurious thermopower. Thermopower measurements, carried out in this set-up are published in reputed journals.
Rapid two-anchor crawling from a milliscale prismatic-push–pull (3P) robot
Authors: Zhou Wei , Gravish Nick
Published: July 2020

Many crawling organisms such as caterpillars and worms use a method of movement in which two or more anchor points alternately push and pull the body forward at a constant frequency. In this paper we present a milliscale push–pull robot which is capable of operating across a wide range of actuation frequencies thus enabling us to expand our understanding of two-anchor locomotion beyond the low-speed regime. We designed and fabricated a milliscale robot which uses anisotropic friction at two oscillating contact points to propel itself forward in a push–pull fashion. In experiments we varied the oscillation frequency, f, over a wide range (10–250 Hz) and observe a non-linear relationship between robot speed over this full frequency range. At low frequency (f < 100 Hz) forward speed increased linearly with frequency. However, at an intermediate push–pull frequency (f > 100 Hz) speed was relatively constant with increasing frequency. Lastly, at higher frequency (f > 170 Hz) the linear speed–frequency relationship returned. The speed–frequency relationship at low actuation frequencies is consistent with previously described two-anchor models and experiments in biology and robotics, however the higher frequency behavior is inconsistent with two-anchor frictional behavior. To understand the locomotion behavior of our system we first develop a deterministic two-anchor model in which contact forces are determined exactly from static or dynamic friction. Our experiments deviate from the model predictions, and through 3D kinematics measurements we confirm that ground contact is intermittent in robot locomotion at higher frequencies. By including probabilistic foot slipping behavior in the two-anchor friction model we are able to describe the three-regimes of robot locomotion.
Teleconnection patterns of precipitation in the Three-River Headwaters region, China
Authors: Dong Yiyang , Zhai Jiaqi , Zhao Yong , Li Haihong , Wang Qingming , Jiang Shan , Chang Huanyu , Ding Zhiyong
Published: July 2020

With the intensification of global warming, spatiotemporal variations in the climate and their mechanisms have received increasing attention. Currently, the relationship between regional precipitation regime, large-scale circulation, and topography, particularly in high-altitude areas such as the Qinghai–Tibet Plateau, are not well understood. Herein, the spatial and temporal variability in the annual and intra-annual (wet and dry periods) precipitation at 33 stations in the Three-River Headwaters (TRH) region from 1967 to 2016 are analysed. Moreover, the empirical orthogonal function and wavelet transform coherence methods are used to analyse the relationships between the different modes of precipitation change and 14 atmospheric circulation indices. The following results were obtained. (1) The mean annual precipitation and mean dry period precipitation significantly increased over the studied period. Annual and intra-annual precipitation showed a spatial southeast-to-northwest decreasing trend. (2) Two main patterns of precipitation were observed during the studied period: a dominant pattern with high- and low-value centres located in southeast and northwest TRH, respectively, and a dipole pattern with more precipitation over southwest TRH and less precipitation over northeast TRH. (3) Precipitation had a negative correlation with latitude, positive correlation with longitude, and nonlinear relationship with elevation. (4) Precipitation changes over various parts of the studied domain were determined based on changes in the weather systems affecting the area, with different indices being correlated with different components during different times of the year.
Topological data analysis reveals parameters with prognostic skill for extreme wildfire size
Authors: Bendick Rebecca , Hoylman Zachary H
Published: July 2020

A topological data analysis (TDA) of 200 000 U.S. wildfires larger than 5 acres indicates that events with the largest final burned areas are associated with systematically low fuel moistures, low precipitation, and high vapor pressure deficits in the 30 days prior to the fire start. These parameters are widely used in empirical fire forecasting tools, thus confirming that an unguided, machine learning (ML) analysis can reproduce known relationships. The simple, short time scale parameters identified can therefore provide quantifiable forecast skill for wildfires with extreme sizes. In contrast, longer aggregates of weather observations for the year prior to fire start, including specific humidity, normalized precipitation indices, average temperature, average precipitation, and vegetation indices are not strongly coupled to extreme fire size, thus afford limited or no enhanced forecast skill. The TDA demonstrates that fuel moistures and short-term weather parameters should optimize the training of ML algorithms for fire forecasting, whilst longer-term climate and ecological measures could be downweighted or omitted. The most useful short-term meteorological and fuels metrics are widely available with low latency for the conterminous U.S, and are not computationally intensive to calculate, suggesting that ML tools using these data streams may suffice to improve situational awareness for wildfire hazards in the U.S.
Political leadership on climate change: the role of health in Obama-era U.S. climate policies
Authors: Workman Annabelle , Blashki Grant , Bowen Kathryn J , Karoly David J , Wiseman John
Published: July 2020

Urgent and ambitious climate action is required to avoid catastrophic climate change and consequent health impacts. Political will is a critical component of the ambitious climate action equation. The current level of political will observed for many national governments is considered inadequate, with numerous political leaders yet to commit to climate action commensurate with the projected risks and responsibilities for their respective jurisdictions. Under the leadership of the Obama administration, however, the United States of America arguably provided an example to the contrary. Strategically utilising an available legislative lever, the Obama administration pursued comparatively ambitious climate change mitigation policies, with health as a core motivation. Analysis of Obama-led climate policies and policy-making strategies provides valuable insight into the utility of health as a motivator for climate action. It also reaffirms that strong political leadership constitutes an essential element in the pursuit of increasingly ambitious climate change policies, particularly in the face of strong opposition.
Local-Wisdom and Its Influence to Disaster Mitigation on the Spatial Configuration of Lakkang Waterfront Settlement
Authors: Syarif E , Asniawaty  , Nadjmi N , Syadzwina A
Published: July 2020

This paper discussed the concept of dwelling and its influence to the disaster-responsive mitigation on the spatial configuration of Lakkang waterfront settlement, as settlement is formed by the local cultural. This research was conducted by using space syntax analysis techniques and supported by the disaster mitigation concept. The result of this study shows that dwelling concepts of Lakkang communities is developed from natural dwelling to collective dwelling. The spatial configuration of Lakkang settlement is developed by collective dwelling. Collective dwelling will form a more integrated space of the space which is formed by natural dwelling. Dwelling culture of the Lakkang people has formed an open space configuration so that the spaces are integrated with each other. The Lakkang settlement is adapted to the natural environment so that disaster can be minimized. The spatial configuration of Lakkang settlement is in accordance with the disaster mitigation concept. The layout of settlements and ecological carrying capacity are the determining factors for disaster response settlements. This paper could be a concept for the development of the waterfront settlements based on local wisdom.
Post-Occupancy Evaluation on Infrastructure Service Performance of Mariso Low Cost Apartment (Rusunawa), Makassar
Authors: Amri N , Idawarni  , Syarif E , Amin S , Siradjuddin Y , Hiromi R
Published: July 2020

This study aims to measure the level of infrastructure service performance of Mariso low-cost apartment (Rusunawa), which is the key to the comfort of occupancy that ensure the sustainability of daily activities both physical and non-physical. Targets to achieve in this research are to formulate the infrastructure service performance according to the standard service of building infrastructure and facilities and as mandated in the standard of planning, building and evaluation of building post-occupancy. This method is used to determine the extent to which the perception of occupants responding to the results of a built environment after more than 10 (ten) years occupied. The applied research method was descriptive research method through the recording and infrastructure service performance analysis by linking between the comfort factor with the standard planning of Mariso low-cost apartment (Rusunawa). The results of the research are the recommendations on the suitability of the service standards/performance infrastructure of the building with the existing conditions of the building with attention to the variable availability of infrastructure that become the focus of research.
Factors Affecting Thermal Comfort of Elementary Schools’ Students in Makassar
Authors: Hamzah B , Mulyadi R , Ishak M T
Published: July 2020

The article aims to analyze the most affecting thermal environmental factors on students’ thermal comfort in elementary schools. The questionnaire has been collected from 1,111 students. The one-minute interval of data measurements was carried out in the 33 classrooms at six primary schools in Makassar. Environmental data involved measurements of air temperature, globe temperature, air velocity, and relative humidity. Students wrote down their personal data and their response to the thermal environments of classrooms in the questionnaire sheets. The results show that the most affecting factor of thermal comfort of students is operative temperature (To). Based on the students’ thermal sensation votes, the operative temperature ranges from 29.1 to 30.0 °C is recommended to provide a comfortable condition for students to learn more successfully in the naturally ventilated primary schools’ classrooms. This result is slightly lower than the neutral temperature obtained from the regression between actual votes and the operative temperature, which was 30.2 °C. The results agree with the neutral temperature calculated using the revised Humphreys adaptive model which give the result of 29.4 °C. The second variable that has a significant effect on the students’ thermal comfort is air velocity. The students felt comfortable at air velocity at about 0.25 m/s and also at air velocity more in the ranges of 1.00 to around 1.50 m/s.
Value of Concrete Compressive Strength on 28 days with Variation of Candlenut Shell Applicated to Plate on a Non-destructive Test Using Hammer Test
Authors: Nasruddin  , Sampebulu V , Mushar P
Published: July 2020

Concrete compressive strength is one of the parameters used to control the quality of a concrete. Concrete compressive strength testing method which is considered the highest level of reliability is a destructive test using a compressive testing machine. Testing requires quite high costs and a longer processing time. But sometimes testing must be done in the scene. Based on the case, a testing tool is needed to measure or determine the compressive strength of concrete without spoil, which is known as the non-destructive test. The tool commonly used for this test is the hammer test. The type of research is experimental. The purpose of this research is to get the compressive strength value of a concrete plate variation of 30% candlenut shells from the test results using a hammer test so as the results can be close to the results of testing using a compressive testing machine (destructive test). The research variable is the testing method (3 point of testing with angle 0°), the age of concrete plate curing, the method of curing (wet curing and dry curing). The number of samples of reinforced concrete slabs is 8 pieces measuring 50cm x 25 cm x 12cm. The research results are Compressive strength of concrete slabs of 30% candlenut shell variations using a Hammer test showed that the concrete strength reached 23-27 Mpa both in wet curing and dry curing or equivalent to the quality of K250 concrete at 28 days. The results also indicate higher values compared to normal concrete slabs.
Identification of Child-Friendly Integrated Public Spaces in Makassar City (Case Study: Losari Beach)
Authors: Ali M , Aliah S E , Fachrul R M , Musdalifah
Published: July 2020

The availability of urban public space supports the survival of the community. The importance of public space sometimes ruled out by the government. The problem that often occurs in urban areas is the transfer of the function of free land to built land. Child Friendly Integrated Public Space (CFIPS) is an open space as a play ground, for the growth and development of children. However, the number and quality of its benefits are still not proportional. In this study taking up waterfront public space in the city of Makassar, case study in the Losari Beach to satisfy the Child Friendly Integrated Public Space aspects, must adjust to the criteria set out in the CFIPS policy. This research was conducted to identify the availability of CFIPS in Makassar City, determine the condition of existing CFIPS and measure the level of visitor satisfaction through direct observation, questionnaires and visitor interviews. The result of this research is the Losari Beach as a friendly public space for children with activities with variable accessibility, safety, comfort, cleanliness and completeness of various facilities of the community views both for the child-friendly aspects.
Soil-Compost Mixture as Alternative Material for Soil Cover Landfill
Authors: Sari K , Ridwan I , Putry M N A
Published: July 2020

One of typical problem in a developing country is the lack of controlling odors, vectors, fires, and litter in the waste landfill. It is known that this problem can be reduced by landfill. However to maintain cover material always available, it is uneasy, especially due to limited budget. This study intends to propose compost-soil mixture as an alternative material using residual soil cover from completed waste landfill. In order to investigate and assess the geotechnical properties of soil-compost mixture as an alternative material, several tests were conducted such as compaction, unconfined compression, and permeability tests. Compaction tests showed 0.4%, 0.8% and 1.2% of compost in soil mixtures results the values of dry density in the range between 1.297 g/cm3 and 1.330 g/cm3, which meet the minimum requirement according to Indiana environmental department USA. Shear strength of compost-soil mixture that derived from results of unconfined compression tests, reduced slightly for additional compost without curing time. However, the values increased sharply for 3 and 7 days of curing time. All the shear strength values of 0.88 kg/cm3 to 34.76 kg/cm3 passed the minimum requirement for cover material according to Environmental Protection Agency (EPA) and Environment Agency. In case of ability of the soil mixture to transmit water, permeability coefficient were 1.5 × 10−3 cm/sec, 7 × 10−4 cm/sec and 3 × 10−4 cm/sec for 0.4%, 0.8% and 1.2% of compost respectively. Referring to modern sanitary landfill and design, it was shown that, the soil mixtures meet minimum requirement for permeability coefficient. To sum up, compost-soil mixtures with composition tested can be considered as material alternative for soil cover in landfill.
Investigation of Air Pollution Impact on Kinta River Water Quality at a Tropical Region
Authors: Mokhtar N A , Madhoun W A , Alazaiza M Y D , Balogun A L , Yahaya N K B E M , Ros F C
Published: July 2020

Critical air quality levels lead to an unhealthy environment which disrupts physical activities and human health. Wet deposition of air pollutants might cause a high concentration of water pollution due to rain water washout of nitrate and particulate matter (PM). This study aimed to investigate the impacts of air pollutants deposition on river water quality in Malaysia. The methodology involved in the analysis of secondary data (January to December 2013) for air quality and river water quality using factor, correlation, and regression. Parameters of air quality were PM10, Nitrate (NO3), ozone (O3) and temperature while water quality data were turbidity, Nitrate and PM10 (Ca, As, Hg, Cd, Cr, Pb, Zn, Cl, Fe, K, Mg, Na). The results show that there were positive correlations between air quality indicators and Kinta river water quality parameters. Correlation matrix shows that in terms of turbidity, air and water data were having 96% similarities. Regarding Nitrate concentrations, air and water records had only 30% of correlation matrix, which can be due to other sources of Nitrate which was agriculture activities near Kinta River. The factor analysis results showed that PM was the main contributor to river water quality particles with 94%.
Model Microsimulation Roundabout Utilities in Makassar
Authors: Pasra M , Hamid S , Faisal A , Yatmar H
Published: July 2020

The vehicle growth is one of the problems affecting traffic congestion. The circulation of entry vehicles and circulating vehicles in confluence made the conflict point. Avoidance the conflict is the need to increase road performance. The roundabout of the road is one of the utilities to increase the performances of traffic and reduce congestion. The prevention step is to maximize the utilities to control and manage the traffic. The roundabout dispersed and controlled the traffic flow. According to Makassar roundabout observation, the queuing and delay of vehicles recently occurs. This study aims to an analysis of the roundabout using the microsimulation Vissim program. The model uses the geometric condition of the road and volume of the vehicle that produce the models based on real condition and validation. This model performed the visual condition and calculated the capacity and shows the emission of the operational vehicle, and the general performances are summarized for operation performances at roundabout confluence sections. The result indicated that the roundabout is still useful to reduce the potential of queuing and delay the time of vehicles, and it needs supervision periodically for preventing the traffic from the potential congestion, especially in developing countries. The research result is useful as a reference for improving the capacity of roundabouts.