High Availability Research Articles

Ethanol and 2-phenylethanol production by bee-isolated Meyerozyma caribbica strains

Investigating the biotechnological potential of wild microorganisms is paramount for optimizing bioprocesses. Given this premise, we looked for yeasts in Brazilian native stingless bees, considering the recognized potential of pollinating insect-associated microorganisms for the production of volatile organic compounds (VOCs). Two yeast strains of the species Meyerozyma caribbica were isolated from bees Scaptotrigona postica and evaluated for their fermentative capacity. Both yeasts were capable of fermenting sucrose (the main sugar used in the Brazilian ethanol industry) with over 90% efficiency and yields of up to 0.504 g/g. Through an experimental design analysis (CCD), it was verified that the ethanol productivity of these yeasts can also benefit from high concentrations of sucrose and low pH values, desirable traits for microorganisms in this biofuel production. At the same time, CCD analyses also showed the great capacity of these M. caribbica strains to produce another alcohol of broad biotechnological interest, 2-phenylethanol. Interestingly, the statistical analyses demonstrated that greater production of this compound can occur at high sugar concentrations and low availability of nitrogen sources, which can be easily achieved using residual low-cost feedstocks. Thus, our results suggest that these M. caribbica strains may be efficiently used in both ethanol and 2-phenylethanol production.

Adsorption of Cr(VI) and phosphate anions by amino-functionalized palm oil fibers.

This work developed a novel sustainable adsorbent (PF-Aq) prepared by the amino-functionalization of palm oil fibers (PF). XPS, SEM/EDS, TGA/DSC, and FT-IR techniques proved the successful functionalization of the PF with the amino group. The PF-Aq adsorbent presents a high adsorption capacity for phosphate and Cr(VI) ions. Adsorption kinetics of the ions onto the PF-Aq followed the general-order models, with 240- and 300-min equilibrium times for phosphate and Cr(VI), respectively. The Freundlich equilibrium model can explain the adsorption of phosphate and Cr(VI) on the PF-Aq. Besides, the maximum adsorption capacities were 151.07mgg-1 for phosphate and 206.08mgg-1 for Cr(VI). The best pH for the adsorption of both ions on PF-Aq was 4.0. Interestingly, adsorption was exothermic for phosphate and endothermic for Cr(VI). The adsorption capacities were reduced by 16% for phosphate and 10% for Cr(VI) after 5 adsorption-desorption cycles, demonstrating the good recyclability of the PF-Aq. It can be concluded that PF-Aq is a relevant adsorbent to uptake phosphate and Cr(VI) from water due to its high adsorption capacity, low cost, recyclability, availability, and fast kinetics. Finally, the excellent adsorption potential results from inserting amino groups in the PF, allowing electrostatic interactions between adsorbent and adsorbate.

Effects of Nest‐Site Availability on Male–Male Competition and the Foraging Costs of Egg Attendance in an Arachnid With Exclusive Paternal Care

ABSTRACTNatural cavities are monopolizable resources used as nest sites across many species exhibiting exclusive male care. However, our understanding of how the availability of this type of reproductive site influences male–male competition and the foraging costs associated with parental care is limited and based on studies of fish. The harvestman Magnispina neptunus offers the opportunity to explore these questions in invertebrates because males defend natural cavities used as oviposition sites and provide exclusive parental care. We hypothesized that low nest availability would increase male–male competition and the foraging costs of egg attendance. To test this hypothesis, we collected observational data in the field and conducted a laboratory experiment with two groups, low and high nest availability. Field data indicate natural cavity scarcity, as only 50% of the males were nest holders. Larger males were more likely to hold nests in the field, but body size did not predict nest ownership in the laboratory. In the field, nests with openings smaller than average were equally occupied by small and large males, while nests with openings larger than average were occupied almost exclusively by large males. The nest opening in the laboratory experiment was adjusted to be equal to the average found in the field, which may have increased nest defensibility, regardless of male size. Thus, prior residency may outweigh body size in determining nest possession. Because nest owners seem to have an advantage over intruders, the costs of abandoning a nest are likely high. This may explain why the frequency of nest takeovers and foraging outside the nests did not differ between experimental groups. In conclusion, although underexplored in empirical studies, external factors, such as the opening size of cavities defended by males of many species with resource‐defense mating systems, may play a key role in the defensibility of nest sites.

Experimenting with artificial shelters to assist habitat restoration for medium‐sized ground‐dwelling mammals

Many terrestrial vertebrates require microhabitat shelter structures for survival. Where anthropogenic or environmental disturbances have degraded or depleted shelter, artificial shelters are increasingly used to provide supplementary habitat for various taxa. However, their application to medium‐sized ground‐dwelling mammals (MGMs) remains largely unexplored. We installed rudimentary artificial shelters in a conservation reserve to emulate the vegetative cover used as refuge by three Australian MGMs: the long‐nosed (Perameles nasuta) and northern brown bandicoots (Isoodon macrourus), and the vulnerable long‐nosed potoroo (Potorous tridactylus). We used multi‐method occupancy modeling and behavioral analysis to compare the detections and behaviors of the target species with those of four non‐target species. Our study design included three plot types (treatments)—artificial shelter, baited lure, and disturbance control—enabling unambiguous evaluation of responses to the shelters. The bandicoots showed no difference in detection among treatments, whereas detection of the potoroo was highest at control plots. Detection of non‐target species was generally highest at baited plots. The target species demonstrated a much higher willingness to enter the shelters compared to the non‐target species. The use of the structures appeared to be exploratory, with no evidence that individuals remained in shelters during the day. There was limited evidence that the shelters reduced the target species' perceptions of predation risk and no evidence that predators were attracted to the shelters. The high availability of natural shelter and our small sample size likely influenced these findings. Nevertheless, they lay the foundation for research and refinement into more effective shelter designs.

MORCoRA: Multi-Objective Refactoring Recommendation Considering Review Availability

Background: Search-based refactoring involves searching for a sequence of refactorings to achieve specific objectives. Although a typical objective is improving code quality, a different perspective is also required; the searched sequence must undergo review before being applied and may not be applied if the review fails or is postponed due to no proper reviewers. Aim: Therefore, it is essential to ensure that the searched sequence of refactorings can be reviewed promptly by reviewers who meet two criteria: (1) having enough expertise and (2) being free of heavy workload. The two criteria are regarded as the review availability of the refactoring sequence. Method: We propose MORCoRA, a multi-objective search-based technique that can search for code quality improvable, semantic preserved, and high review availability possessed refactoring sequences and corresponding proper reviewers. Results: We evaluate MORCoRA on six open-source repositories. The quantitative analysis reveals that MORCoRA can effectively recommend refactoring sequences that fit the requirements. The qualitative analysis demonstrates that the refactorings recommended by MORCoRA can enhance code quality and effectively address code smells. Furthermore, the recommended reviewers for those refactorings possess high expertise and are available to review. Conclusions: We recommend that refactoring recommenders consider both the impact on quality improvement and the developer resources required for review when recommending refactorings.

Active mission assignment for improving the effectiveness of opportunistic maintenance in a fleet of mission-critical systems

In a fleet of mission-critical systems, maintaining high availability for each individual system is vital to ensure consistent fleet readiness to meet mission demands. This study introduces a novel mission assignment strategy aimed at actively aligning maintenance schedules within each system to maximise opportunistic maintenance potential, thus enhancing system availability. However, solely focusing on system-level assignments may result in simultaneous maintenance needs across the fleet, leading to resource conflicts. The proposed strategy addresses this issue by coordinating mission assignments to consider both the alignment of schedules within a system and the even distribution of schedules among systems to prevent fleet-level conflicts. Two operational conditions, intra-system and inter-system balance, are defined to evaluate the criticality of each system at both system and fleet levels. Based on these conditions, scheduling rules are developed to determine assignment priority across the fleet in a two-phase process. Simulation studies demonstrate the effectiveness of this approach, showing a 2% improvement in system availability, equivalent to a two-month reduction in downtime across the fleet over a one-year period. The results underscore the advantages of the proposed strategy in optimising maintenance operations in complex fleet environments with diverse mission requirements.

Condition-based maintenance policy for shared service-oriented leased equipment

Due to growing consumer demands for immediacy, personalization, and high availability, equipment manufacturers are venturing into the sharing market with expanded shared leasing services. While selling usage rights of equipment, they provide additional services to the consumer in the role of equipment operators, such as free maintenance and swap. However, uncertain usage rates and return times in the shared model pose significant maintenance challenges. This paper proposes a personalized condition-based maintenance (CBM) policy accounting for these uncertainties and heterogeneous consumer usage patterns. By considering inspection, maintenance, and penalty costs, we minimize the long-run expected maintenance cost per unit of time for operators. In the numerical example, we compare our policy against fixed inspection interval CBM policy and non-fixed inspection interval CBM under average usage rate, demonstrating that personalized CBM reduces maintenance costs. Sensitivity analysis provides some managerial insights. Firstly, operators should adjust the number of free swaps strategically to manage the intensity of equipment swaps, and strike a balance between the increased maintenance costs due to the swap intensity enhancement and the improved user satisfaction and equipment availability resulting from the increased number of free swaps. Secondly, when the acceleration effect of imperfect maintenance on the degradation rate is strengthened, operators should prioritize reducing the frequency of imperfect maintenance and increasing the frequency of perfect preventive maintenance. Moreover, operators must make strategic investments in their maintenance actions, balancing maintenance costs and penalty costs to develop cost-effective imperfect maintenance improvement factors.

Optimizing the resistivity of colloidal SnO2 thin films by ion implantation and annealing

Tin oxide (SnO2) is a critical material for a wide range of applications, such as in perovskite solar cells, gas sensors, as well as for photocatalysis. For these applications the transparency to visible light, high availability, cheap fabrication process and high conductivity of SnO2 benefits its commercial deployment. In this paper, we demonstrate that the resistivity of widely colloidal SnO2 can be reduced by noble gas ion beam modification. After low energy argon implantation with a fluence of 4×1015 at.cm−2 at 25keV and annealing at 200°C in air, the resistivity of as-deposited film was reduced from (178±6)μΩcm to (133±5)μΩcm, a reduction of 25%. Hall effect measurements showed that the primary cause of this is the increase in carrier concentration from (8.1±0.3)×1020 cm−3 to (9.9±0.3)×1020 cm−3. Annealing at 200°C resulted in the removal of defect clusters introduced by implantation, while annealing at 300°C resulted in the oxidation of the films, increasing their resistivity. The concentration of oxygen vacancy defects can be controlled by a combination of low energy noble gas ion implantation and annealing, providing promising performance increases for potential applications of SnO2 where a low resistivity is crucial.

Managing Employee Retention Concerns: Evidence from U.S. Census Data

ABSTRACT Using Census microdata on 28,000 manufacturing plants, we examine how firms manage employee retention concerns. In response to reductions in the local unemployment rate, plants take additional steps beyond increasing compensation. First, plants adjust bonus architecture to ensure bonuses can be paid. Second, plants offer more agency to employees by deploying high-involvement work practices that generate longer-term commitment. Third, plants pull these retention levers less when they have high availability and use of data as this reduces the adverse effects of employee turnover on organizational knowledge. These results are robust to using the fracking revolution as a shock increasing firms’ retention concerns. Additionally, we observe that although compensation increases tend to spill over to other plants within the same firm—aligning with theories of inequity aversion—adjustments to bonus architecture and the provision of employee agency do not, suggesting these may be more cost-effective strategies for multiplant firms. JEL Classifications: J63; M51; M54.

Modeling continental US stream water quality using long-short term memory and weighted regressions on time, discharge, and season

The temporal dynamics of solute export from catchments are challenging to quantify and model due to confounding hydrological and biogeochemical processes and sparse measurements. Conventionally, the concentration-discharge relationship (C-Q) and statistical approaches to describe it, such as the Weighted Regressions on Time, Discharge and Seasons (WRTDS), have been widely used. Recently, deep learning (DL) approaches, especially Long-Short-Term-Memory (LSTM) models, have shown predictive capability for discharge, temperature, and dissolved oxygen. However, it is not clear if such advances can be expanded to water quality variables driven by complex subsurface biogeochemical processes. This work evaluates the performance of LSTM and WRTDS for 20 water quality variables across ~500 catchments in the continental US. We find that LSTM does not markedly outperform WRTDS in our dataset, potentially limited by the current measurement capabilities of water quality across CONUS. Both models present similar performance patterns across water quality variables, with the LSTM displaying better performance for nutrients compared to weathering-derived solutes. Additionally, the LSTM does not benefit from flexibility in the inputs. For example, incorporation of climate data that constrains streamflow generation, does not significantly improve the LSTM performance. We also find that data availability is not a straightforward predictor of LSTM model performance, although higher availability tends to stabilize performance. To fully assess the potential of the LSTM model, it may be necessary to use a higher frequency dataset across the CONUS, which does not exist today. To evaluate the dynamics of C-Q patterns relative to model performance, we introduce a “simplicity index” considering both the seasonality in the concentration pattern and the linearity in the C-Q relationship, or the C-Q-t pattern. The simplicity index is strongly correlated with model performance and differentiates the underlying controls on water quality dynamics. Further DL experiments and model-intercomparison highlight the strengths and deficiencies of existing frameworks, pointing to the need for further hydrogeochemical theories that are amenable to complex basins and solutes.

Development and validation of a natural language processing algorithm using electronic health record data to identify patients with breast cancer with low social support.

421 Background: Social support is important to the management of breast cancer treatment. Our team has developed data from electronic health record (EHR) data into structured ‘concept groups’ that will form the basis for the development of EHRsupport, a computable, EHR-based measure of social support. We report the evaluation of these concept groups against chart review as a part of our validation. Methods: We built a natural language processing (NLP) algorithm on clinical notes in 7,989 women diagnosed from January 2006 to September 2021 with invasive breast cancer. We identified and developed 10 concept groups from unstructured data: 1) living situation, 2) marital/partner status, 3) parenthood status, 4) visit support (accompanied patient to ≥1 visit, patient attended alone at ≥1 visit), 5) friends/other support, 6) explicit positive or negative mentions of social support, 7) mention of a deceased person, 8) transportation issues, 9) relationship conflict or stress, and 10) social isolation. We validated concept groups against the charts of 100 patients randomly drawn from the broader patient population (nonoverlapping with the training data set) also around the time (-1 to +3 months) of diagnosis. Results: Concept group data availability ranged from 1.3% social isolation to 98.3% for living situation. Specificity and negative predictive values were moderate to high for all concept groups. Sensitivity and positive predictive values were moderate to high for concept groups with high data availability (Table) and lower for concept groups with low data availability. Conclusions: Data on social support have been available since the advent of Epic in 2006 and our NLP-based algorithm accurately captured data within the EHR that were systematically collected supporting the development of a clinical tool that can be used to identify patients at risk of low social support. EHRsupport concept groups, data availability (n=7,989), and evaluation vs. chart review. Availability (%) Sensitivity Specificity PPV NPV Living situation (e.g., alone or not) 98.3 100 92 61 100 Partner/spouse 92.0 85 100 100 81 Parenthood status 88.8 95 80 93 83 Visit support 82.9 92 77 96 59 Positive mentions social support *46.9 75 100 100 70 Negative mentions social support 33 99 67 96 Friend/other support 46.8 81 81 79 83 Deceased person 39.9 86 97 95 90 Transportation issues 14.6 80 85 22 99 Relationship conflict/stress 7.7 25 95 29 94 *Availability of positive and negative mentions of social support.

Cofactor F420 tail length distribution in different environmental samples

Cofactor F420 is an electron carrier playing a crucial role in a variety of microorganisms during redox reactions of the primary and secondary metabolism due to its low redox potential and thus arouses increasing interest. In this study, cofactor F420 glutamyl tail length spectra in various habitats like manure, compost, soil, and digester sludge samples and their respective microbial communities were investigated using high performance liquid chromatography and an amplicon sequencing approach A previous in-silico study was used to identify F420 producing microorganisms. The highest concentration of cofactor F420 could be achieved in the horse manure, digester sludge, and mixed manure samples, which was approximately 100-fold higher than in all the other samples. The high content of the cofactor in the samples with high O2 availability pointed to the important role of the cofactor not only in redox reactions of anaerobic but also for aerobic microorganisms and indicated its ubiquitous character. The most abundant derivate was F420-3 comprising the largest part of the cofactor derivates in seven out of ten samples. The high abundance of F420-3 in samples with distinct properties (e.g. O2 and H2O availability) showed its important role in redox reactions of the primary and secondary metabolism among prokaryotes.

Picophytoplankton prevail year-round in the Elbe estuary.

Picophytoplankton are important primary producers, but not always adequately recognized, for example, due to methodological limitations. In this study, we combined flow cytometry and metabarcoding to investigate seasonal and spatial patterns of picophytoplankton abundance and community composition in the Elbe estuary. Due to the mixing of freshwater and seawater and the tidal currents this ecosystem is characterized by typical estuarine features such as salinity gradients and high turbidity. Picophytoplankton (mostly picoeukaryotes such as Mychonastes and Minidiscus) contributed on average 70% (SD = 14%) to the total phytoplankton counts. In summer picocyanobacteria (e.g., Synechococcus) played a more significant role. The contributions of picophytoplankton to the total phytoplankton were particularly high from summer to winter as well as in the mid estuary. However, at salinities of around 10 PSU in the mixing area of freshwater and seawater, the proportion of picophytoplankton was comparably low (average 49%, SD = 13%). Our results indicate that picophytoplankton prevail in the Elbe estuary year-round with respect to cell counts. Picophytoplankton could occupy important niche positions to maintain primary production under extreme conditions where larger phytoplankton might struggle (e.g., at high or low temperature, high turbidity, and in areas with high grazing pressure) and also benefit from high nutrient availability here. However, we did not find evidence that they played a particularly significant role at the salinity interface. Our study highlights the importance of including picophytoplankton when assessing estuarine phytoplankton as has been suggested for other ecosystems such as oceans.

Blockchain for digital healthcare: case ttudies and adoption challenges

Background The healthcare industry is significantly transforming toward digital and smart healthcare. Blockchain, as an emerging distributed collaborative paradigm, offers a promising solution for ensuring trustworthiness and high availability of services in this evolving healthcare. This paper aims to provide a comprehensive survey of blockchain-based applications in smart healthcare. Methods We first present real-world blockchain use cases in smart healthcare and related fields, outlining the motivations for this study. Next, we review cutting-edge blockchain applications in various domains, including health data sharing, public health management, drug supply chains, insurance claims, and the Internet of Medical Things. A detailed analysis of several blockchain-based healthcare data sharing scenarios is included. Results The findings illustrate the diverse applications of blockchain technology in enhancing healthcare systems, along with a detailed examination of challenges related to technical implementation and adoption. Conclusion We discuss the challenges facing blockchain integration in smart healthcare and propose potential solutions to guide future research in this area.

Quantification and assessment of the atmospheric boundary layer height measured during the AWAKEN experiment by a scanning LiDAR

The atmospheric boundary layer (ABL) height plays a key role in many atmospheric processes as one of the dominant flow length scales. However, a systematic quantification of the ABL height over the entire range of scales (i.e., with periods ranging from one minute to one year) is still lacking in literature. In this work, the ABL height is quantified based on high-resolution measurements collected by a scanning pulsed Doppler LiDAR during the recent American WAKE experimeNt (AWAKEN) campaign. The high availability of ABL height estimates (≈2200 collected over one year and each of them based on 10-min averaged statistics) allows to robustly assess five different ABL height models, i.e., one for convective thermal conditions and four for stable conditions. Thermal condition is quantified by a stability parameter spanning three orders of magnitude and probed by near-ground 3D sonic anemometry. The free-atmosphere stability, quantified by the Brunt–Väisälä frequency, is both calculated from simultaneous radiosonde measurements and obtained from the best fit of two of the chosen ABL height models. Good agreement is found between the data and three of the chosen models, quantified by mean absolute errors on the ABL height between 281 and 585 m. Furthermore, the seasonal variability of the convective ABL height model parameters (−15% to +23% with respect to the year baseline) agrees with the variability of buoyancy-generated turbulence caused by the variation in solar radiation throughout the year.

Integrated assessment of water security in D-8 countries

In terms of evaluating the water security situation of communities, it is necessary to use appropriate indicators. To do this, composite indicators are especially useful for policy-making on water resources, aiming to enhance water security, implementation, and monitoring of policy actions. The composite indicators of water security at the national level reflect the country's status in terms of water resource sustainability, human well-being, and water environment. In this study, the composite indicators of water security for D-8 countries were investigated in various dimensions using the data envelopment analysis model. Moreover, the status of selected countries was examined with regard to indicators related to the dimension of water security sustainability. The results provided by the proposed model showed that Malaysia, Bangladesh, Indonesia, Nigeria, and Turkey have better positions regarding the sustainability dimension compared to other countries. The water exploitation intensity in these countries was less than 40 %. Furthermore, the level of water availability in Malaysia, Bangladesh, and Indonesia was higher than 7000 cubic meters per person. It is worth noting that Low exploitation intensity and high availability of water in a country increased its water security in terms of sustainability dimension. The low water availability and very high water exploitation in Iran, Pakistan, and Egypt exacerbate their insecurity in the sustainability dimension. Due to the importance of the sustainability dimension in determining the water security status of countries, it is recommended to take this dimension into account.

تحليل وتصميم شبكة محلية لاسلكية آمنة للحرم الجامعي في الجامعات الليبية

This research presents the wireless university campus network and discusses about the strengths and weaknesses of Design a secure wireless campus networks for ABC University in Libya, and about the costs and advantages of different vendor solutions. Wireless offers mobility and is available in locations where a wired outlet doesn't exist. The disadvantages of wireless include some minor interference problems and a quickly evolving and competitive group of standards. The purpose of the research is designing and implementing a secure campus network for Libyan university based on Cisco equipments. Moreover, the research can provide practical experience in network design, configuration, and security for helping organizations and institutions protect their network resources and data. Two end products or deliverables will result from the research: the first is a new architectural design for an efficient and advanced WLAN-friendly network to ensure the high performance of the data transaction process and ensure high availability of data transmissions. The second product is a report for network administrators or network architecture to guide users towards the achievement of WLAN-friendly by utilising advanced networking tools and technologies. Keywords: - Campus network; Wireless Mesh Network; wireless network; Encryption; Cisco equipment; security.

Optimization and performance improvement of distributed data storage in hybrid storage systems

With the rapid development of information technology, the storage and processing of massive data has become one of the important challenges facing the current computing field. Traditional centralized storage systems have been unable to meet the needs of big data applications, while distributed storage systems have become the infrastructure of modern data centers because of their high scalability and high availability. However, in practical applications, a single distributed storage model is often difficult to balance cost-effectiveness and performance requirements. Therefore, this paper proposes a hybrid storage system model combining local storage and cloud storage resources and discusses a series of optimization strategies for this model. The focus of the research is to improve the overall performance of the system through the design of intelligent data sharding, redundancy and fault tolerance mechanisms, and the application of effective load balancing technology. The effectiveness and superiority of the proposed method are verified by testing and analyzing several typical application scenarios on the experimental platform. The experimental results show that the optimized hybrid storage system not only significantly improves the speed of data access, but also effectively reduces the storage cost, demonstrating its potential in future large-scale data management.

Environmental uncertainty and entrepreneurial orientation in collectivist and individualist cultures: evidence from Brazil and Belgium

ABSTRACT A fundamental premise of the information processing approach in entrepreneurship theory is that the distribution and processing of information is key to opportunity identification. We propose that collectivist-individualist cultural values influence the efficacy of information processing leading to different levels of entrepreneurial orientation (EO). Specifically, we submit that collectivism enhances shared information processing and goal setting in a dynamic environment, while individualism facilitates creativity and divergent thinking that can help EO if sufficient informational input is available. To empirically verify our theory, we study the relationships using survey and archival data from a sample of 487 firms in six industries in Brazil and Belgium, two countries that contrast in collectivism-individualism. Consistent with our predictions, we find higher EO in the collectivist culture of Brazil under high environmental dynamism and low information availability, and this difference is increased by strategic planning.

Leveraging AWS and Java Microservices: An Analysis of Amazon\'s Scalable E-commerce Architecture

Abstract: This article presents a comprehensive case study of Amazon's journey in building a robust and scalable e-commerce platform capable of handling millions of daily transactions while maintaining high availability and performance. We examine the critical architectural decisions that facilitated Amazon's transition from a monolithic structure to a microservices-based architecture, leveraging Java and various AWS cloud services. The article explores key components of Amazon's scalable infrastructure, including the implementation of DynamoDB for high-performance database needs and the use of Elastic Load Balancing to ensure fault tolerance. We analyze the challenges encountered during this transformation and the solutions developed to address them. The article also discusses the resulting improvements in scalability, reliability, and cost-efficiency that have contributed to Amazon's position as the world's largest online retailer. Our findings provide valuable insights into best practices for architecting large-scale, cloud-native e-commerce platforms and offer implications for future developments in the field of distributed systems and cloud computing