Plastic is a general term used for a wide range of high molecular weight organic polymers obtained mostly from the various hydrocarbon and petroleum derivatives. There is an ever-increasing trend ...towards the production and consumption of plastics due to their extensive industrial and domestic applications. However, a wide spectrum of these polymers is non-biodegradable with few exceptions. The extensive use of plastics, lack of waste management, and casual community behavior towards their proper disposal pose a significant threat to the environment. This has raised growing concerns among various stakeholders to devise policies and innovative strategies for plastic waste management, use of biodegradable polymers especially in packaging, and educating people for their proper disposal. Current polymer degradation strategies rely on chemical, thermal, photo, and biological procedures. In the presence of proper waste management strategies coupled with industrially controlled biodegradation facilities, the use of biodegradable plastics for some applications such as packaging or health industry is a promising and attractive option for economic, environmental, and health benefits. This review highlights the classification of plastics with special emphasis on biodegradable plastics and their rational use, the identified mechanisms of plastic biodegradation, the microorganisms involved in biodegradation, and the current insights into the research on biodegradable plastics. The review has also identified the research gaps in plastic biodegradation followed by future research directions.
How different cultures react and respond given a crisis is predominant in a society's norms and political will to combat the situation. Often, the decisions made are necessitated by events, social ...pressure, or the need of the hour, which may not represent the nation's will. While some are pleased with it, others might show resentment. Coronavirus (COVID-19) brought a mix of similar emotions from the nations towards the decisions taken by their respective governments. Social media was bombarded with posts containing both positive and negative sentiments on the COVID-19, pandemic, lockdown, and hashtags past couple of months. Despite geographically close, many neighboring countries reacted differently to one another. For instance, Denmark and Sweden, which share many similarities, stood poles apart on the decision taken by their respective governments. Yet, their nation's support was mostly unanimous, unlike the South Asian neighboring countries where people showed a lot of anxiety and resentment. The purpose of this study is to analyze reaction of citizens from different cultures to the novel Coronavirus and people's sentiment about subsequent actions taken by different countries. Deep long short-term memory (LSTM) models used for estimating the sentiment polarity and emotions from extracted tweets have been trained to achieve state-of-the-art accuracy on the sentiment140 dataset. The use of emoticons showed a unique and novel way of validating the supervised deep learning models on tweets extracted from Twitter.
Contemporary estimates of glacier changes are necessary to assess the impact of climate change, associated hazards and water resources management. Glaciers in High Mountain Asia (HMA) are mostly ...retreating except the Karakoram and western Kunlun Shan, confirmed by remote sensing measurements. However, ground validation with precise measurements of these mass balance estimates are scarce. This study selected Guliya ice cap in the western Kunlun Shan to observe its recent changes regarding surface dynamics and mass balance using ASTER DEM of 2005 and 2015. Our findings indicate that one of the north-facing glaciers surged (with no previous surging history) during July and early November 2015, advancing at about 8 m per day on average. The mass balance shows a balance condition +0.01 ± 0.02 m w.e. a−1. The ICESat data (2004–2008) at selected locations compared to dGPS data collected in the field during 2015, indicating a minute difference of 0.03 ± 0.05 m a−1 with ASTER data in the same area. Our findings suggest that Guliya ice cap in the western Kunlun Shan is in equilibrium state following a similar pattern (mass gain or stable conditions) as observed previously.
•Mass balance of Guliya ice cap is stable between 2005 and 2015.•ICESat and dGPS results between 2004 and 2015 confirm these results.•A north-facing glacier in Guliya ice cap surged during July and November 2015.•The surge was striking considering the nearby Aru glacier collapse in 2016.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Flow-based intrusion detection is an innovative way of detecting intrusions in high-speed networks. Flow-based intrusion detection only inspects the packet header and does not analyze the packet ...payload. This paper provides a comprehensive survey of current state of the art in flow-based intrusion detection. It also describes the available flow-based datasets used for evaluation of flow-based intrusion detection systems. The paper proposes a taxonomy for flow-based intrusion detection systems on the basis of the technique used for detection of maliciousness in flow records. We review the architecture and evaluation results of available flow-based intrusion detection systems. We also identify important research challenges for future research in the area of flow-based intrusion detection.
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Climate extremes, such as heat waves, droughts, extreme rainfall can lead to harvest failures, flooding and consequently threaten the food security worldwide. Improving our understanding about ...climate extremes can mitigate the worst impacts of climate change and extremes. The objective here is to investigate the changes in climate and climate extremes by considering two time slices (i.e., 1962–1990 and 1991–2019) in all climate zones of Pakistan by utilizing observed data from 54 meteorological stations. Different statistical methods and techniques were applied on observed station data to assess changes in temperature, precipitation and spatio-temporal trends of climatic extremes over Pakistan from 1962 to 2019. The Mann-Kendal test demonstrated increasing precipitation (DJF) and decreasing maximum and minimum temperatures (JJA) at the meteorological stations located in the Karakoram region during 1962–1990. The decadal analysis, on the other hand, showed a decrease in precipitation during 1991–2019 and an increase in temperature (maximum and minimum) during 2010–2019, which is consistent with the recently observed slight mass loss of glaciers related to the Karakoram Anomaly. These changes are highly significant at 5% level of significance at most of the stations. In case of temperature extremes, summer days (SU25) increased except in zone 4, TX10p (cold days) decreased across the country during 1962–1990, except for zones 1 and 2. TX90p (warm days) increased between 1991–2019, with the exception of zone 5, and decreased during 1962–1990, with the exception of zones 2 and 5. The spatio-temporal trend of consecutive dry days (CDD) indicated a rising tendency from 1991 to 2019, with the exception of zone 4, which showed a decreasing trend. PRCPTOT (annual total wet-day precipitation), R10 (number of heavy precipitation days), R20 (number of very heavy precipitation days), and R25mm (very heavy precipitation days) increased (decreased) considerably in the North Pakistan during 1962–1990 (1991–2019). The findings of this study can help to address some of the sustainable development goals related climate action, hunger and environment. In addition, the findings can help in developing sustainable adaptation and mitigation strategies against climate change and extremes. As the climate and extremes conditions are not the uniform in all climate zone, therefore, it is suggested to the formers and agriculture department to harvest crops resilient to the climatic condition of each zone. Temperature has increasing trend in the northern Pakistan, therefore, the concerned stakeholders need to make rational plans for higher river flow/flood situation due to snow and glacier melt.
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Although glaciers in High Mountain Asia produce an enormous amount of water used by downstream populations, they remain poorly observed in the field. This study presents a geodetic mass balance of ...the glaciers in the Astore Basin (with differential GPS (dGPS) measurements on Harcho glacier) between 1999 and 2016. Changes near the terminus of Harcho glacier (below 3800 m a.s.l.) featured heterogeneous surface elevation changes, whereas the middle section shows the most negative changes. The surface elevation changes were positive above 4200 m a.s.l. The average annual mass balance was −0.08 ± 0.07 m w.e. a−1 derived from a dGPS and DEM comparison whereas Advanced Spaceborne Thermal Emission and Reflection Radiometer DEM-based results show a slightly positive, that is 0.03 ± 0.24 m w.e. a−1 in the same period. In contrast, the terminus indicates a substantial retreat of ~368 m (4.5 m a−1) between 1934 and 2016. The average mass balance of 19 glaciers (>2 km2) covering ~60% of the total glaciers in the Basin exhibit no net mass loss in the period of 2000−2016 and follow a pattern similar to adjacent Karakoram glaciers.
Low-resource languages are gaining much-needed attention with the advent of deep learning models and pre-trained word embedding. Though spoken by more than 230 million people worldwide, Urdu is one ...such low-resource language that has recently gained popularity online and is attracting a lot of attention and support from the research community. One challenge faced by such resource-constrained languages is the scarcity of publicly available large-scale datasets for conducting any meaningful study. In this paper, we address this challenge by collecting the first-ever large-scale Urdu Tweet Dataset for sentiment analysis and emotion recognition. The dataset consists of a staggering number of 1, 140, 821 tweets in the Urdu language. Obviously, manual labeling of such a large number of tweets would have been tedious, error-prone, and humanly impossible; therefore, the paper also proposes a weakly supervised approach to label tweets automatically. Emoticons used within the tweets, in addition to SentiWordNet, are utilized to propose a weakly supervised labeling approach to categorize extracted tweets into positive, negative, and neutral categories. Baseline deep learning models are implemented to compute the accuracy of three labeling approaches, i.e., VADER, TextBlob, and our proposed weakly supervised approach. Unlike the weakly supervised labeling approach, the VADER and TextBlob put most tweets as neutral and show a high correlation between the two. This is largely attributed to the fact that these models do not consider emoticons for assigning polarity.
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Laser-induced breakdown spectroscopy (LIBS) is regarded as the future superstar for chemical analysis, but the relatively high measurement uncertainty and error remain the persistent challenges for ...its technological development as well as wide applications. In the present work, mechanisms of measurement uncertainty generation and basic principle of signal uncertainty and matrix effects impacting quantification performance were explained. Furthermore, methods for raw signal improvement including sample preparation, system optimization, and especially plasma modulation, which modulates the laser-induced plasma evolution process for higher signal repeatability and signal-to-noise ratio, were reviewed and discussed. Different LIBS mathematical quantification methods including calibration-free methods and calibration methods, which were classified into physical-principle based calibration model, data-driven based calibration model, and hybrid model, were discussed and compared. Overall, a framework of quantification improvement strategy including key steps and main way-out was summarized and recommended for LIBS future development.
•A framework strategy to for LIBS quantification improvement was postulated.•Recent progress of the mechanism of LIBS signal uncertainty generation was summarized.•Various plasma modulation techniques for raw signal quality improvement were presented and compared.•Synergetic use of physical model and data-driven method for LIBS quantification was illustrated and recommended.
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Snow is a significant component of the ecosystem and
water resources in high-mountain Asia (HMA). Therefore, accurate,
continuous, and long-term snow monitoring is indispensable for the water
...resources management and economic development. The present study improves the
Moderate Resolution Imaging Spectroradiometer (MODIS) onboard Terra and Aqua satellites
8 d (“d” denotes “day”) composite snow cover Collection 6 (C6) products, named MOD10A2.006 (Terra) and
MYD10A2.006 (Aqua), for HMA with a multistep approach. The primary
purpose of this study was to reduce uncertainty in the Terra–Aqua MODIS snow cover products and generate a combined snow cover product. For reducing
underestimation mainly caused by cloud cover, we used seasonal, temporal,
and spatial filters. For reducing overestimation caused by MODIS sensors, we
combined Terra and Aqua MODIS snow cover products, considering snow only if a
pixel represents snow in both the products; otherwise it is classified as no snow, unlike some previous
studies which consider snow if any of the Terra or Aqua product identifies snow. Our
methodology generates a new product which removes a significant amount of
uncertainty in Terra and Aqua MODIS 8 d composite C6 products comprising
46 % overestimation and 3.66 % underestimation, mainly caused by sensor
limitations and cloud cover, respectively. The results were validated using
Landsat 8 data, both for winter and summer at 20
well-distributed sites in the study area. Our validated adopted methodology
improved accuracy by 10 % on average, compared to Landsat data. The final product covers the period from 2002 to 2018, comprising a
combination of snow and glaciers created by merging Randolph Glacier
Inventory version 6.0 (RGI 6.0) separated as debris-covered
and debris-free with the final snow product MOYDGL06*. We have
processed approximately 746 images of both Terra and
Aqua MODIS snow containing approximately 100 000 satellite
individual images. Furthermore, this product can serve as a valuable
input dataset for hydrological and glaciological modelling to assess the melt
contribution of snow-covered areas. The data, which
can be used in various climatological and water-related studies, are available for end users at https://doi.org/10.1594/PANGAEA.901821 (Muhammad
and Thapa, 2019).
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The catastrophic floods that hit Pakistan in summer 2022 represent the latest example of climate change-induced extreme events occurring in South Asia. In addition to the dramatic impact on ...population and infrastructures, this event threatened UNESCO World Heritage Sites (WHS) and properties of national interest. However, while a wealth of national and international mapping initiatives were conducted based on satellite imagery to assess damage to people, buildings and economic goods, the impact caused to archaeological sites and monuments has not been fully unveiled yet. To bridge this gap and provide an integrated approach that can be used by local end-users to assess damage and, in turn, collect evidence to inform and improve risk management plans, the present paper integrates Sentinel-1 and 2 imagery and mapping products derived from them (e.g., Copernicus Emergency Management Service Global Flood Mapping) with ground-truthing and geospatial datasets. Through a multidisciplinary collaboration between geologists, archaeologists, remote sensing and satellite image analysts, the integration methodology was tested on UNESCO and other heritage sites of national relevance located in the two mostly affected regions of Khyber Pakhtunkhwa and Sindh that were intentionally selected to represent different typologies of cultural heritage and governance in Pakistan. Finally, the information extracted from the present analysis was assessed in relation to the current national and international legislations, the official state of conservation reports and the activities conducted at each site to protect them against flood events. Given the accessibility to ready-to-use Copernicus products and that the present analysis can be replicated over time and other sites, the proposed methodology provides a feasible means to exploit satellite data in post-disaster mapping situations and contribute to the decision-making process for risk management.
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