bluuebunny/crossref_metadata_2025 huggingface dataset:
Three-dimensional hydrodynamic simulations of the upper atmosphere of π Men c: Comparison with Lyα transit observations
Authors: Shaikhislamov I. F. , Fossati L. , Khodachenko M. L. , Lammer H. , García Muñoz A. , Youngblood A. , Dwivedi N. K. , Rumenskikh M. S.
Published: June 2020

Context. π Men c is the first planet to have been discovered by the Transiting Exoplanet Survey Satellite. It orbits a bright, nearby star and has a relatively low average density, making it an excellent target for atmospheric characterisation. The existing planetary upper atmosphere models of π Men c predict significant atmospheric escape, but Lyα transit observations indicate the non-detection of hydrogen escaping from the planet.

Aims. Our study is aimed at constraining the conditions of the wind and high-energy emission of the host star and reproducing the non-detection of Lyα planetary absorption.

Methods. We modelled the escaping planetary atmosphere, the stellar wind, and their interaction employing a multi-fluid, three-dimensional hydrodynamic code. We assumed a planetary atmosphere composed of hydrogen and helium. We ran models varying the stellar high-energy emission and stellar mass-loss rate, and, for each case, we further computed the Lyα synthetic planetary atmospheric absorption and compared it with the observations.

Results. We find that a non-detection of Lyα in absorption employing the stellar high-energy emission estimated from far-ultraviolet and X-ray data requires a stellar wind with a stellar mass-loss rate about six times lower than solar. This result is a consequence of the fact that, for π Men c, detectable Lyα absorption can be caused exclusively by energetic neutral atoms, which become more abundant with increasing velocity or density of the stellar wind. By considering, instead, that the star has a solar-like wind, the non-detection requires a stellar ionising radiation about four times higher than estimated. The reason for this is that despite the fact that a stronger stellar high-energy emission ionises hydrogen more rapidly, it also increases the upper atmosphere heating and expansion, pushing the interaction region with the stellar wind farther away from the planet, where the planet atmospheric density that remains neutral becomes smaller and the production of energetic neutral atoms less efficient.

Conclusions. Comparing the results of our grid of models with what is expected and estimated for the stellar wind and high-energy emission, respectively, we support the idea that it is likely that the atmosphere of π Men c is not hydrogen-dominated. Therefore, future observations should focus on the search for planetary atmospheric absorption at the position of lines of heavier elements, such as He, C, and O.
Kontrastmitteldosierung und Optimierungspotenzial in der CT
Authors: Steffens Petra , Aichbauer Nadine
Published: June 2020

Grundsätzlich wird bei CT-Untersuchungen empfohlen, die zu applizierende Kontrastmittelmenge über das Körpergewicht zu berechnen, wobei ebenfalls noch Protokolle mit fixen Kontrastmittelmengen angewendet werden. Im Folgenden werden berücksichtigungswürdige Aspekte im Zusammenhang mit einer Kontrastmittelapplikation aufgezeigt sowie Berechnungsmodelle zur Ermittlung der individuell benötigten Kontrastmittelmenge vorgestellt und diskutiert.
Design of a Low-Cost, Wearable Device for Kinematic Analysis in Physical Therapy Settings
Authors: Hua Andrew , Johnson Nicole , Quinton Joshua , Chaudhary Pratik , Buchner David , Hernandez Manuel E.
Published: June 2020

Background Unsupervised home exercise is a major component of physical therapy (PT). This study proposes an inexpensive, inertial measurement unit-based wearable device to capture kinematic data to facilitate exercise. However, conveying and interpreting kinematic data to non-experts poses a challenge due to the complexity and background knowledge required that most patients lack.

Objectives The objectives of this study were to identify key user interface and user experience features that would likely improve device adoption and assess participant receptiveness toward the device.

Methods Fifty participants were recruited to perform nine upper extremity exercises while wearing the device. Prior to exercise, participants completed an orientation of the device, which included examples of software graphics with exercise data. Surveys that measured receptiveness toward the device, software graphics, and ergonomics were given before and after exercise.

Results Participants were highly receptive to the device with 90% of the participants likely to use the device during PT. Participants understood how the simple kinematic data could be used to aid exercise, but the data could be difficult to comprehend with more complex movements. Devices should incorporate wireless sensors and emphasize ease of wear.

Conclusion Device-guided home physical rehabilitation can allow for individualized treatment protocols and improve exercise self-efficacy through kinematic analysis. Future studies should implement clinical testing to evaluate the impact a wearable device can have on rehabilitation outcomes.
Applying FAIR Principles to Improve Data Searchability of Emergency Department Datasets: A Case Study for HCUP-SEDD
Authors: Bhatia Karishma , Tanch James , Chen Elizabeth S. , Sarkar Indra Neil
Published: June 2020

Background There is a recognized need to improve how scholarly data are managed and accessed. The scientific community has proposed the findable, accessible, interoperable, and reusable (FAIR) data principles to address this issue.

Objective The objective of this case study was to develop a system for improving the FAIRness of Healthcare Cost and Utilization Project's State Emergency Department Databases (HCUP's SEDD) within the context of data catalog availability.

Methods A search tool, EDCat (Emergency Department Catalog), was designed to improve the “FAIRness” of electronic health databases and tested on datasets from HCUP-SEDD. ElasticSearch was used as a database for EDCat's search engine. Datasets were curated and defined. Searchable data dictionary-related elements and unified medical language system (UMLS) concepts were included in the curated metadata. Functionality to standardize search terms using UMLS concepts was added to the user interface.

Results The EDCat system improved the overall FAIRness of HCUP-SEDD by improving the findability of individual datasets and increasing the efficacy of searches for specific data elements and data types.

Discussion The databases considered for this case study were limited in number as few data distributors make the data dictionaries of datasets available. The publication of data dictionaries should be encouraged through the FAIR principles, and further efforts should be made to improve the specificity and measurability of the FAIR principles.

Conclusion In this case study, the distribution of datasets from HCUP-SEDD was made more FAIR through the development of a search tool, EDCat. EDCat will be evaluated and developed further to include datasets from other sources.
‘I couldn’t say the words’: communicative bodies and spaces in parents’ encounters with nonsuicidal self-injury
Authors: Steggals Peter , Lawler Steph , Graham Ruth
Published: June 2020

There is a growing recognition that nonsuicidal self-injury commonly incorporates communicative and interactional dimensions. But regardless of whether we approach self-injury within the terms of deliberate interpersonal communication, it is undeniably something that conveys a significant impact into the social and communicative field between people. As such, it is something that can be approached and analysed as communicative in this more general sense. In this paper, we draw on 13 in-depth qualitative interviews with the parents of people who self-injure, conducted for a larger pilot study, to explore some of these more general communicative processes, spaces and impacts associated with self-injury. By providing a phenomenologically informed examination of parents' experiences, we argue that self-injury is in fact a richly communicative phenomenon, albeit one that cannot be adequately mapped using the traditional sender–receiver communication paradigm. To provide a more nuanced mapping, we look beyond this paradigm to include more subtle, ambiguous, pre-reflexive and bodily forms of communication. Indeed, self-injury offers a particularly powerful case study with which to think through a more complex model of communication, one that connects the interpersonal, intersubjective and intercorporeal levels, and that, as such, is more appropriate to the sociologies of everyday life and embodiment.
Surface states of carbon dots and their influences on luminescence
Authors: Ding Hui , Li Xue-Hua , Chen Xiao-Bo , Wei Ji-Shi , Li Xiao-Bing , Xiong Huan-Ming
Published: June 2020

Luminescent carbon dots (CDs) have received increasing attention from many fields during the past decade. Unfortunately, the luminescent mechanisms of CDs remain unclear due to insufficient experimental and theoretical knowledge, which significantly hinders the development of CDs with desired optical properties. Currently, surface states of CDs, which are based on synergistic hybridization between the carbon backbones and the connected functional groups, have been considered as the dominant luminescence origins. This tutorial paper, thus, aims to offer an overview of the key features on the surface of CDs, such as particle size, surface functional groups, defects and heteroatom doping, and their influences on the photoluminescence of CDs. In addition, optical characteristics of surface state-derived luminescence emissions of CDs are also summarized. Finally, the potential approaches of characterizing surface states of CDs are introduced, followed by an outlook of synthesizing high-quality CDs through modulation of the surface states.
Heterogeneous surface charge confining an electrolyte solution
Authors: Mußotter Maximilian , Bier Markus , Dietrich S.
Published: June 2020

The structure of dilute electrolyte solutions close to a surface carrying a spatially inhomogeneous surface charge distribution is investigated by means of classical density functional theory within the approach of fundamental measure theory. For electrolyte solutions, the influence of these inhomogeneities is particularly strong because the corresponding characteristic length scale is the Debye length, which is large compared to molecular sizes. Here, a fully three-dimensional investigation is performed, which accounts explicitly for the solvent particles, and thus provides insight into effects caused by ion–solvent coupling. The present study introduces a versatile framework to analyze a broad range of types of surface charge heterogeneities even beyond the linear response regime. This reveals a sensitive dependence of the number density profiles of the fluid components and of the electrostatic potential on the magnitude of the charge as well as on the details of the surface charge patterns at small scales.
Optical properties of Sydney aerosols
Authors: Box Gail P. , Hallal Taleb
Published: June 2020

Aerosol chemistry for PM2.5 and PM10 (particulate matter less than 2.5- and 10-μm aerodynamic diameter) samples collected in the Sydney region between November 2002 and December 2003 had been used to estimate size-resolved refractive index for Sydney. Seasonal PM10–2.5 chemistry was obtained by subtracting seasonal PM2.5 from seasonal PM10 chemical composition. The chemical compounds present were determined from the elemental composition using two methods: the SCAPE 2 chemical thermodynamic model and aerosol types based on marker elements. Refractive index was then calculated using a mass fraction approach. Both methods agreed within the error bars indicating that useful optical properties can be derived from elemental chemistry. For the fine mode (PM2.5), the real component of the refractive index was 1.46 ± 0.07 with no seasonal variation, but there were sea-sonal variations in imaginary component, 0.05 ± 0.02 in summer and 0.23 ± 0.05 in spring. The coarse mode (PM10–2.5) real refractive index was constant throughout the year at 1.47 ± 0.09, whereas the im-aginary refractive index was 0.01 ± 0.04 in summer and 0.04 ± 0.06 in spring. Representative refractive indices were then used to calculate aerosol scattering properties for three different size distributions to illustrate how this information could be used.
Dynamics of 2015 positive Indian Ocean Dipole
Authors: Utari Putri Adia , Khakim Mokhamad Yusup Nur , Setiabudidaya Dedi , Iskandar Iskhaq
Published: June 2020

Evolution of typical positive Indian Ocean Dipole (pIOD) event was dominated by a significant sea-surface temperature (SST) cooling in the south-eastern tropical Indian Ocean. Interestingly, during the evolution of 2015 pIOD event, the SST in the south-eastern tropical Indian Ocean did not reveal significant cooling, instead anomalous strong SST warming took place in the western tropical Indian Ocean off the East African coast. This anomalous SST warming was associated with a weakening of the Asian summer monsoon. Furthermore, analysis on the mixed layer heat budget demonstrated that the evolution of the 2015 pIOD event could be attributed mainly to the air-sea heat flux. By decomposing the air-sea heat flux, it is found that reduced latent heat loss plays an important role on the SST warming in the western pole and keeping SST warm in the eastern pole. We note that a residual term also may play a role during the initial development of the event. In contrast to the SST pattern, the subsurface temperature revealed a clear positive dipole pattern. Shallow (deep) 20°C isothermal layer in the eastern (western) equatorial Indian Ocean was observed during boreal summer. This robust subsurface dipole pattern indicated that the subsurface ocean response was largely wind driven through the equatorial wave dynamics as previously suggested.
Seasonal climate summary for the southern hemisphere (summer 2016–17): a season of extremes despite neutral ENSO, IOD
Authors: Hague Ben
Published: June 2020

This is a summary of the southern hemisphere atmospheric circulation patterns and meteorological indices for summer 2016–17; an account of seasonal rainfall and temperature for the Australian region is also provided. Although indices for the El Niño–Southern Oscillation (ENSO) and the Indian Ocean Dipole (IOD) represented typical neutral condition for these drivers, evidence of other climate drivers can be found in the land, ocean and atmosphere data from this time. The Southern Annular Mode appeared to have had some effect on rainfall in the east of Australia, and the Madden–Julian Oscillation active periods produced heavy rain in the tropical north. Despite neutral ENSO and IOD, extreme temperatures, in some areas highest on record, occurred in northern NSW and southern Queensland. High sea-surface temperatures caused further severe bleaching on the Great Barrier Reef.
Seasonal climate summary for the southern hemisphere (autumn 2017): the Great Barrier Reef experiences coral bleaching during El Niño–Southern Oscillation neutral conditions
Authors: Smith Grant A.
Published: June 2020

Austral autumn 2017 was classified as neutral in terms of the El Niño–Southern Oscillation (ENSO), although tropical rainfall and sub-surface Pacific Ocean temperature anomalies were indicative of a weak La Niña. Despite this, autumn 2017 was anomalously warm formost of Australia, consistent with the warming trend that has been observed for the last several decades due to global warming. The mean temperatures for Queensland, New South Wales, Victoria, Tasmania and South Australiawere all amongst the top 10. The mean maximum temperature for all of Australia was seventh warmest on record, and amongst the top 10 for all states but Western Australia, with a region of warmest maximum temperature on record in western Queensland. The mean minimum temperature was also above average nationally, and amongst top 10 for Queensland, Victoria and Tasmania. In terms of rainfall, there were very mixed results, with wetter than average for the east coast, western Victoria and parts of Western Australia, and drier than average for western Tasmania, western Queensland, the southeastern portion of the Northern Territory and the far western portion of Western Australia. Dry conditions in Tasmania and southwest Western Australia were likely due to a positive Southern Annular Mode, and the broader west coast and central dry conditions were likely due to cooler eastern Indian Ocean sea-surface temperatures (SSTs) that limited the supply of moisture available to the atmosphere across the country. Other significant events during autumn 2017 were the coral bleaching in the Great Barrier Reef (GBR), cyclone Debbie andmuch lower than average Antarctic sea-ice extent. Coral bleaching in the GBR is usually associated on broad scales with strong El Niño events but is becoming more common in ENSO neutral years due to global warming. The southern GBR was saved from warm SST anomalies by severe tropical cyclone Debbie which caused ocean cooling in late March and flooding in Queensland and New SouthWales. The Antarctic sea-ice extent was second lowest on record for autumn, with the March extent being lowest on record.
Using global navigation satellite system data for real-time moisture analysis and forecasting over the Australian
region I. The system
Authors: Marshall John Le , Norman Robert , Howard David , Rennie Susan , Moore Michael , Kaplon Jan , Xiao Yi , Zhang Kefei , Wang Carl , Cate Ara , Lehmann Paul , Wang Xiaoming , Steinle Peter , Tingwell Chris , Le Tan , Rohm Witold , Ren Diandong
Published: June 2020

The use of high spatial and temporal resolution data assimilation and forecasting around Australia’s capital cities and rural land provided an opportunity to improve moisture analysis and forecasting. To support this endeavour, RMIT University and Geoscience Australia worked with the Bureau of Meteorology (BoM) to provide real-time GNSS (global navigation satellite system) zenith total delay (ZTD) data over the Australian region, from which a high-resolution total water vapour field for SE Australia could be determined. The ZTD data could play an important role in high-resolution data assimilation by providing mesoscale moisture data coverage from existing GNSS surface stations over significant areas of the Australian continent. The data were used by the BoM’s high-resolution ACCESS-C3 capital city numerical weather prediction (NWP) systems, the ACCESS-G3 Global system and had been used by the ACCESS-R2-Regional NWP model. A description of the data collection and analysis system is provided. An example of the application of these local GNSS data for a heavy rainfall event over SE Australia/Victoria is shown using the 1.5-km resolution ACCESS-C3 model, which was being prepared for operational use. The results from the test were assessed qualitatively, synoptically and also examined quantitatively using the Fractions Skills Score which showed the reasonableness of the forecasts and demonstrated the potential for improving rainfall forecasts over south-eastern Australia by the inclusion of ZTD data in constructing the moisture field. These data have been accepted for operational use in NWP.
A comment on temperature measurement at automatic weather stations in Australia
Authors: Ayers G. P.
Published: June 2020

Two versions of 1-min air-temperature data recorded at Bureau Automatic Weather Stations (AWSs) were compared in three case studies. The aim was to evaluate the difference between 1-min data represented by a measurement at the last second of each minute, compared with an average of four or five 1-s measurements made during the minute. Frequency distributions of the difference between these two values were produced for 44 000 min in three monthly data sets, January and July 2016 and September 2017. Diurnal and seasonal changes in standard deviation of the temperature differences showed that minute-to-minute fluctuations were driven by solar irradiance as the source of turbulent kinetic energy in the planetary boundary layer. Fluctuations in the difference between the two versions of 1-min data were so small overnight in all months that minimum temperature (Tmin) was the same using both methods. In midsummer, any difference between the two values for maximum temperature (Tmax) was greatest at midday. Tmax could be up by 0.1 K higher in the 1-s data compared with Tmax averaged from four measurements in the minute, but less often than 1 min in five. A follow-up test for September 2017 at Mildura when a new Tmax record was set found the difference immaterial, with Tmax the same for the averaged or 1-s values. Thus while the two versions of 1-min air-temperature data showed fluctuating small differences, largest at midday in summer, for the 3 months studied at both sites, fluctuations were too small to cause bias in climatological air-temperature records. This accorded with a numerical experiment confirming the Bureau’s advice that thermal inertia in the AWS measurement systems ensured that its 1-s data represented averages over the prior 40–80 s, providing a 1-min average of air temperature in accord with World Meteorological Organization requirements.
The warm and extremely dry spring in 2015 in Tasmania contained the fingerprint of human influence on the climate
Authors: Grose Michael R. , Black Mitchell T. , Wang Guomin , King Andrew D. , Hope Pandora , Karoly David J.
Published: June 2020

Tasmania saw a warm and very dry spring and summer in 2015–16, including a record dry October, which had significant, wide-ranging impacts. A previous study using two probabilistic event-attribution techniques found a small but statistically significant increase in the likelihood of the record dry October due to anthropogenic influence. Given the human signal was less clear amid natural variability for rainfall compared to temperature extremes, here we provided further evidence and context for this finding. An additional attribution method supported the October rainfall finding, and the median attributable risk to human influence in the three methods was ~25%, 48% and 75%. The results suggested that human influence on rainfall was partly through increased sea level pressure in the mid-latitudes associated with fewer rainbearing systems, a circulation driver that was consistent with recent trends that have been attributed to human influence. Dry conditions were also driven by a positive Indian Ocean Dipole and El Niño at the time, but this study could not reliably estimate the effect of human influence on these phenomena, as each model gave a different estimate of the ocean warming pattern. Along with rainfall, attribution modelling showed a role for human influence in higher temperature and evaporation through October 2015, as well as a high drought index throughout spring. Confidence in the attribution of a human signal on this extreme dry event increased as multiple attribution methods agreed, a plausible atmospheric circulation driver was identified, and temperature and evaporation also showed an anthropogenic signal.
Analysis of a southerly buster event and associated solitary waves
Authors: Wang Shuang , Leslie Lance , Rai Tapan , Speer Milton , Kuleshov Yuriy
Published: June 2020

This paper is a detailed case study of the southerly buster of 6–7 October 2015, along the New South Wales coast. It takes advantage of recently available Himawari-8 high temporal- and spatial-resolution satellite data, and other observational data. The data analyses support the widespread view that the southerly buster is a density current, coastally trapped by the Great Dividing Range. In addition, it appeared that solitary waves developed in this event because the prefrontal boundary layer was shallow and stable. A simplified density current model produced speeds matching well with observational southerly buster data, at both Nowra and Sydney airports. Extending the density current theory, to include inertia-gravity effects, suggested that the solitary waves travel at a speed of ~20% faster than the density current. This speed difference was consistent with the high-resolution satellite data, which shows the solitary waves moving increasingly ahead of the leading edge of the density current.
Environmental interactions during the extreme rain event associated with ex-tropical cyclone Oswald (2013)
Authors: Leroux Marie-Dominique , Nguyen-Hankinson Mai C. , Davidson Noel E. , Callaghan Jeffrey , Tory Kevin , Wain Alan , Huang Xinmei
Published: June 2020

Tropical cyclone (TC) Oswald made landfall over north-east Australia as a minimal or Category 1 TC on the Australian scale on 21 January 2013. As it moved southward, it intensified over land and produced extreme rainfall for nearly 7 days. Tornadoes were reported and confirmed. Tragically, seven people died and insurance estimates were ~$1 billion. It is demonstrated that the event was associated with an interaction between the ex-Oswald circulation and an amplifying Rossby wave, which propagated north-eastward from high latitudes. Diagnoses showed that as the wave amplified and broke, a potential vorticity (PV) anomaly (PVA) extended to mid-levels, moved equatorward, merged with or axisymmetrised the ex-Oswald circulation through mid-levels. Backward trajectories from locations regularly scattered within the mid-level circulation illustrated that the storm transitioned from an isolated vortex into a circulation which was strongly influenced by its environment for at least 5 days. During this interaction, PV was advected from the environment towards the storm through mid-levels. The heavy rain coincided with the commencement and maintenance of this PV injection. The PV injection is quantified and shown to be consistent with PV advection by the mean radial flow. In addition, eddy angular momentum convergence in the mid- to upper levels coincided with an intensification of the circulation through this region. This was first related to outward transport of anticyclonic momentum by the asymmetric outflow at upper levels, followed by inward transport of cyclonic momentum by the asymmetric inflow. It is shown that the environmental interaction had an impact on vortex structure changes, rainfall and tornado development. We propose that the environmental processes influenced the ascent within the storm (1) via differential vorticity advection and baroclinic forcing, as the mid- to upper level PVA approached the circulation and (2) by low- to mid-level warm air advection.
High-impact thunderstorms of the Brisbane metropolitan area
Authors: Soderholm Joshua S. , Turner Kathryn I. , Brook Jordan P. , Wedd Tony , Callaghan Jeffery
Published: June 2020

Accurate thunderstorm warnings in the hours-to-minutes preceding impact are often limited by the complex evolution of the mesoscale atmospheric environment. To accurately capture these complexities, analysis of observations remained central to operational short-term nowcasting predictions of thunderstorms. Over the past 40 years, multiple highimpact thunderstorm events have impacted the Brisbane Metropolitan Area (BMA) of South East Queensland resulting in significant insured losses. Four of these high-impact events were the focus of the following work. These cases included three events that resulted in the greatest insured losses for the BMA, exceeding AU$4 billion (2017) (18 January 1985, 16 November 2008 and 27 November 2014) and a fourth significant event (24 December 1989). Synthesis of previous work indicates that the four high-impact cases occurred during a south-easterly change with strengthening winds ahead of the change, suggesting commonalities may exist that can be exploited for forecasting. This paper provides a detailed observational analysis of the environment and convective storms from the four BMA events to explore discriminating characteristics that may improve the skill of nowcasting. For the four BMA events, significant deep convection was observed along the change for the hours prior to the change’s arrival at the Brisbane Airport, potentially acting as an early indicator of favourable conditions for high-impact thunderstorms. It was found that the timing of the south-easterly change through Brisbane was also highly correlated for all events, occurring within a 90-min window during the mid-afternoon convective heating maximum. Despite the destructive severe weather, upper air conditions were marginal for supporting organised thunderstorms, highlighting the importance of capturing mesoscale processes, such as the south-easterly change. To further understand possible discriminators of the four high-impact BMA cases, a 10-year climatology of the mesoscale and synoptic environment associated with south-easterly change events was developed for the warm season months of November to January. It is shown that although only a small number of events are associated with high-impact BMA thunderstorms, these events share a set of conditions relating to the prechange wind shift, timing of the south-easterly change and radar signatures.
Seasonal climate summary for the southern hemisphere (summer 2017–18): an exceptionally warm season for Australia – a short-lived and weak La Niña
Authors: Tihema Tamika
Published: June 2020

This is a summary of the southern hemisphere atmospheric circulation patterns and meteorological indices for summer 2017–18; an account of seasonal rainfall and temperature for the Australian region is also provided. A short-lived and weak La Niña developed but decayed by the end of February 2018. Sea-surface temperatures were exceptionally warm in the Tasman Sea from late 2017 to early 2018. It was an exceptionally warm summer for Australia, and the third-warmest mean temperature on record for the nation. Summer rainfall was close to the long-term average for Australia, with aboveaverage rainfall in west and below-average rainfall in the east.
The influence of large amplitude planetary waves on the Antarctic ozone hole of austral spring 2017
Authors: Evtushevsky Oleksandr , Klekociuk Andrew R. , Kravchenko Volodymyr , Milinevsky Gennadi , Grytsai Asen
Published: June 2020

Quasi-stationary planetary wave activity in the lower Antarctic stratosphere in the late austral winter was an important contributor to the preconditioning of the ozone hole in spring 2017. Observations show that the ozone hole area (OHA) in spring 2017 was at the level of 1980s, that is, almost half the maximum size in 2000s. The observed OHA was close to that forecasted based on a least-squares linear regression between wave amplitude in August and OHA in September–November. We show that the key factor which contributed to the preconditioning of the Antarctic stratosphere for a relatively small ozone hole in the spring of 2017 was the development of large-amplitude stratospheric planetary waves of zonal wave numbers 1 and 2 in late winter. The waves likely originated from tropospheric wave trains and promoted the development of strong mid-latitude anticyclones in the lower stratosphere which interacted with the stratospheric polar vortex and strongly eroded the vortex in August and September, mitigating the overall level of ozone loss.
Sensibility analysis of the electrical impedance parameters by the Monte Carlo method
Authors: Vega S P , Corzo S P , Miranda D A
Published: June 2020

Electrical properties of biological tissues are used to analyze its state in different practical applications, e.g., assessing the risk of cancer. The modeling of electrical properties usually is performed by circuital models or semiempirical models as Cole-Cole. Still, another option is available, the application of the generalized effective medium theory of induced polarization. In the framework of the effective medium theory, we proposed a model for biological tissues which we called MOPET. This model links physiological parameters of tissues with their electrical properties. However, it has a higher number of parameters than the Cole-Cole and circuital models. This large number of parameters is a limitation for the use of effective medium theory to describe the electrical properties of tissue and also suggests that some of these parameters have negligible effects. We used a Monte Carlo simulation to study the effect of each MOPET parameter on the electrical impedance spectra, where uniform random variables were used to simulate the variability of the parameters of this model. We found that the heterogeneity coefficient is the most sensible parameter, i.e., a variation above 1% in this parameter alters enormously the impedance spectra.
Spectroscopic Observation of Wolf-Rayet Stars: Study of Expansion Velocity and Mass Loss as Contributors of Interstellar Matter Enrichment
Authors: Adhyaqsa Azlizan , Malasan Hakim L , Aprilia  , Puspitarini Lucky
Published: June 2020

Wolf-Rayet (WR) stars exhibit broad emission lines in their spectra. Based on the featured lines, they are classified into three types: nitrogen-rich WN, carbon-rich WC, and oxygen-rich WO. Broad emission lines indicate high expansion velocity and also previous studies showed that WR stars possessed higher mass-loss rates compared with another type of stars. Thus, it is suggested that the expansion velocity and the mass loss of WR stars play a role in the enrichment of interstellar matter. Our observations were conducted between July 2018 and June 2019 using NEO-R1000 (R∼1000) spectrograph with spectral range 4500-7000Å at the Bosscha Observatory and consisted of WN and WC type stars. Data reduction and expansion velocities determination were carried out using IRAF with longslit-transform routine and Gaussian fitting respectively. To obtain mass-loss rates, we compared our observed spectra with models provided by Potsdam Wolf-Rayet Models (PoWR). In several cases, the contribution of WR stars can be directly observed as Wolf-Rayet nebulae, whose structures are influenced by the high expansion velocity of the nearby WR stars. Assuming that the total of WR stars in the Milky Way is ∼ 2600, we estimated that the population release ∼ 0.507 M⊙ of material annually into Galactic environment.
Mobile Campaign of Sky Brightness Measurement in Indonesia
Authors: Admiranto A G , Haida SK , Priyatikanto R , Maryam S , Ellyyani  , Suryana N
Published: June 2020

The bright sky caused by light pollution is a problem for astronomical research. One of the first steps in dealing with the effects of light pollution is to calculate the level of light pollution. Measurement of sky brightness using Sky Quality Meter (SQM) can be done massively through mobile campaign/observations. LAPAN conducted such observations at several places namely Sumatera Barat, Sumedang, Jawa Tengah, Jawa Timur and Kupang by using SQM attached on vehicles. Those campaigns covers 80 to 980 km journey and the total distance traveled was about 2870 km. The obtained data show that the sky brightness above regions surveyed vary from 10 magnitude per arcsec2 (mpsas), especially around Surabaya, Jawa Timur to 22 mpsas. The results then compared radiance map of the Earth surface from Visible Infrared Imaging Radiometer Suite (VIIRS) aboard Suomi National Polar Orbiting Partnership (NPP). Moderate correlations between in-situ sky brightness data and the radiance map are achieved. Further analyses are required prior to utilization of those relations in the development of Indonesia’s sky brightness map which is presumably more accurate than the existing global map of sky brightness.
Morphology and evolution of coronal holes at the wavelengths of 171 Å, 193 Å, and 211 Å in the Solar Cycle 24
Authors: Astuti I K D , Herdiwijaya D
Published: June 2020

Coronal holes are an area that appears dark in the corona, which is observable in EUV and X-ray wavelengths. This area has an open magnetic field structure. The magnetogram image showed that the coronal hole has one polarity (unipolar). Commonly, the shape and size of the coronal hole at the poles are related to the structural strength of the magnetic field. Because of this unipolar nature, the coronal hole becomes a source of the high-speed solar wind, which can cause a geomagnetic storm. The number, size, and position of the coronal hole vary as a function of the solar cycle, with the reversal of magnetic polarity every 11 years. The characteristics of the coronal hole will be different at the maximum and minimum phases of the solar cycle. Aims of this study are to determine the morphology of coronal hole based on the area, magnetic field strength, open magnetic flux, and the evolution of the coronal hole according to latitude during minimum solar activity (or spotless days) and maximum at the Solar Cycle 24. The method applied in this study is CHIMERA (Coronal Hole Identification via Multi-thermal Emission Recognition Algorithm). There are relations between magnetic field strength and magnetic flux with areas of coronal holes from September 2010 to May 2019 that follow the exponential and linear distributions.
Investigation of the latitudinal occurrence rate of ionospheric plasma bubble in case of strong and weak pre–reversal enhancement in Southeast Asia
Authors: Olla A , Abadi P , Srigutomo W
Published: June 2020

We used ionosonde and GPS receivers during March–April in 2004–2005 and 2011–2015 to investigate the latitudinal variation of equatorial plasma bubble (EPB) occurrence rate in cases of strong and weak pre-reversal enhancement (PRE). The ionosonde at Chumphon in Thailand was used to estimate the PRE strength. Ten GPS receivers in Southeast Asia, ranging from magnetic latitude (ML) of 4.4°S to 21.6°S, were used to investigate the latitudinal variation of EPB occurrence rate. In the case of strong PRE, the EPB occurrence rates decrease from 38.9% to 34.9% at ML of 4.4°S–7.2°S. Continuously, the occurrence rate increases and reaches the peak (44%) at ML of 9.3°S; afterward, the occurrence rate rapidly decreases and reaches below 5% at ML of 21.6°S. In the case of weak PRE, the occurrence rate decreases from 21.8% at ML of 4.4°S, seems constant (15.3%–16%) at ML of 8.2°S–12.1°S, and reaches less than 5% at ML of 16.1°S. Generally, the EPB occurrence rate and its latitudinal extension in case of strong PRE are higher than that in case of weak PRE. Interestingly, we found that the latitudinal occurrence rate peak of the EPB in case of strong is farther than that in case of weak PRE.
Al-Si-Zn Behaviouron Interface of AR500 Steel and AA7075 Aluminium Alloy BrazedJoint
Authors: Muhamed M. N. , Omar M.Z. , Abdullah S. , Sajuri Z. , Zamri W.F.H.W.
Published: June 2020

The brazing of steel and aluminium alloy using low melting point aluminium based fillers has been extensively studied and the technique has been used in many industries, especially the automotive industry. The strength and failure mode of AR500 steel and AA7075 aluminium alloy brazing joint using the Al-Si-Zn filler metal will be measured and calculated in this paper. However, the adverse effect of intermetallic phases formation on the joint strength has limited the application of this joining method.These dissimilar metals possessing a high strength joint would be of benefit to industry especially in reducing the weight of products. The torch brazing method using Al-Si-Zn base filler metal wasused to join AR500 steel and AA7075 aluminium alloy in this study. The intermetallic phase formation of the brazing on was investigated by scanning electron microscopy and the mechanical strength of the joints was evaluated by shear testing, flexural testing and low velocity impact testing. A maximum shear load of 6460 N was obtained. The presence of intermetallic phases was found to have some effect on the strength of the brazed joint. However, overall, this brazing process using Al-Si-Zn filler metal facilitates the joining of these dissimilar metals to improve the mechanical properties of the joint
Mechanical Properties of Hybrid FRP Arrangement of Glass and Kenaf fibres
Authors: Bahiyah Baba N. , Haikal Abdul Halim M. , Zin N.A.M. , Amin M.A.M.
Published: June 2020

The study discussed the mechanical properties of hybrid arrangement of glass and Kenaf fibre reinforced plastic (FRP). There are two types of hybrid arrangementscomparedwith one controlled arrangement of 100% Kenaf fibre. The glass fibre types used in the study are chopped, woven and 3-dimensional. The FRP was fabricated via hand lay-up method using the two types of matrix namely epoxy 1,2 and polyester resins. Parameters evaluated were fibre hybrid FRP arrangement and fibre orientation for the two types of composite with two different matrix resins. The mechanical properties evaluated on the hybrid FRP arrangement are tensile strength, elastic modulus, elongation at break and water absorption. The mechanical properties of 36 composites samples were conducted by Instrons Machine 3382 according to ASTM D-638-10a. The physical property of nine samples was performed using water absorption according to ASTM D 570-99. These tests were carried out to determine the effect of mechanical behaviour for all hybrid FRP arrangements. It was found that hybrid FRP arrangement #1 with layers of fibreglass 3D-woven-chopped-woven-3D give the outstanding properties both in polyester and epoxy matrices. However, adding Kenaf reduce the mechanical properties and increase water absorption.
Effect of Using Windscreen Glass Waste Powder (WGWP) As Cement Replacement on the Mechanical Properties of Mortar
Authors: Anisah N.N. , Awang M. , Kartini K.
Published: June 2020

Sustainability issues have obtained major attentions around the globe. In this regard, there are challenges which the cement and glass industries are facing due to the high greenhouse gases emissions, the intensive use of energy and the reduction of natural resources on earth. However, the chemical compositions and the pozzolanic properties of waste glass are very encouraging for its use in cement and concrete industries and to provide an environment-friendly solution. For sustainability, it is high time to look into the possibility of replacing cement with windscreen waste glass. A study was conducted on the effects of various proportions of windscreen glass waste powder (WGWP) on the compressive strength of mortar. The mortar was prepared by incorporating several compositions of WGWP (0%, 5%, 10%, 15% and 20% by weight of cement), while three cement to sand (C:S) ratios of 1:2.5, 1:3.0 and 1:3.5 were employed. Fixed water to cement (w/c) ratio of 0.5 was used for this study. The samples were water cured and the assessment of the strength performance of mortar cubes was carried out at 7 and 28 days. Results have shown that WGWP has good pozzolanic properties. In term of compressive strength, it was observed that employing C:S ratio of 1:3.0 is better than 1:2.5 and 1:3.5 of C:S ratio.
Synthesis of Biodiesel from Waste Cooking Oil by Alkali Catalyzed Transesterification
Authors: Shamsudin Mohd Syaharulhafizi Bin Sulong , Bin Abdul Aziz Azharin Shah , Dabwan Ahmed H. A.
Published: June 2020

Biodiesel is an alternative fuel to petroleum diesel because it is renewable sources and considered to be smart waste management solution for used cooking oil since plenty amount of waste cooking oil is being produced from households and restaurants. Irresponsible practice to get rid of this waste is by pouring it down the sink or drain. However this practice causes damage mainly to the ecosystem (water pollution). In this study, biodiesel was synthesized from waste cooking oil by alkali catalyzed transesterification method. Alkali transesterification is a reaction between oil and alcohol in presence of alkali catalyst. Methanol and sodium hydroxide were used in this transesterification. Treated oil and sodium methoxide mix at constant temperature for certain period to yield methyl ester and glycerin. Characterization was carried out by using thermal gravimetric analysis, differential scanning calorimetry, and normal analytical methods mainly for density and viscosity. This study shows that biodiesel was successfully synthesized from waste cooking oil and characterization of the synthesize biodiesel was almost similar to the conventional diesel. From this, it can be concluded that pollution caused by disposal of waste cooking oil can be turned into value-added product.
Cube Polygon: A New Modified Euler Method to Improve Accuracy of Ordinary Differential Equation (ODE)
Authors: Nooraida S. , Nurhafizah M.M.Y. , Anis M.S. , Fahmi A.M.M. , Syarul A.W.F. , Iliana A.M.
Published: June 2020

Ordinary Differential Equation (ODEs) problems can solve using Euler method. Euler method suitable for first-order numerical and it is an effective and easy method. The objective of this paper is to suggest a new scheme for better accuracy. The accuracy is determined by comparing with exact solution using average concept. This paper proposes Cube Polygon as modified Euler method to improved accuracy and complexity. A set of simulation were carried out to demonstrate the accuracy of the proposed method. Testing has been done into SCILAB 6.0 by recording the maximum error. Results indicate that Cube Polygon provide more accurate results and reducing complexity for both smaller and higher step size.
Influence of Sn dopant on ZnO Thin Film for Formaldehyde Detection
Authors: Ishak S , Johari S , Ramli M M
Published: June 2020

In this work, structural, morphological, electrical and gas sensing of ZnO and Sn doped ZnO thin film at different atomic percentage (0.5at%, 1.0at% and 1.5at%) had been studied. The precursor was prepared by sol-gel method and deposited on an IDE glass substrate by using spin coating technique. The effects of the dopant was then characterized through XRD, AFM, SEM and Agilent LCR Meter. Based on the XRD results, it was found that all films showed the highest diffraction peak intensity at (002) with crystallite size in the range of 8-33nm. Meanwhile the morphological properties from AFM and SEM showed an improvement in surface roughness from 16.7nm to 5.48nm and decrease the grain size from 45.42nm to 40.99nm in the presence of Sn dopant. Based on the image, the grains were uniformly distributed and ZnO thin film showed the hexagonal wurtzite structure, which proved the XRD result. Among all the samples, 1.0at% Sn doped showed the best result for detection of formaldehyde at 0.6ppm which up to 96% compare to undoped, 26.04% at 150°C. The response and recovery time was between 4-16 seconds. This showed that the presence of Sn can help to improve the conductivity of the ZnO thin film.
On the Investigations of Chip-on-Board Ultra-Violet Sensor by Screen Printing of GaN Powder
Authors: Beh Khi Poay , Kamarulakmal Nurul Liyana , Rasiman Nabihah , Abdalrheem Raed , Umar Muttakka , Yam Fong Kwong , Lim Hwee San , Hassan Zainuriah
Published: June 2020

In this work, the characteristics of a chip-on-board screen printed GaN UV sensor was investigated. On the sensing element, GaN powders were obtained through ammonolysis of Ga2O3 at 1000°C under NH3 flow. The UV sensor platform was prepared using soft-lithography method, resulted in patterned circuit board. For the screen printing process, GaN powder is mixed with ethylcellulose/ethanol, subsequently deposited on the electrode pairs. The pure GaN sensor exhibited oscillations and change in amplitude upon UV sensing. This could be ascribed to high intrinsic resistance and parasitic capacitance and inductance. To mitigate this effect, rGO fillers were added and showed discern responds. Both sensors (with and without rGO) showed sensitiviy at 300 and 30% respectively, while the current magnitude for the latter was 54 times higher than that of former.