Destination Site Research Articles

Non-Abelian sandpile automata with height restrictions.

We have studied the properties of a sandpile automata under the constraint of height restriction of sand columns. In this sandpile, an active site transfers a grain to a neighboring site if and only if the height of the sand column at the destination site is less than a preassigned value n_{c}. This sandpile was studied by Dickman etal. [Phys. Rev. E 66, 016111 (2002)1063-651X10.1103/PhysRevE.66.016111] in a conserved system with a fixed number of sand grains. In contrast, we have studied the avalanche dynamics of the driven sandpile under the open boundary conditions. The deterministic dynamics of the Bak, Tang, and Wiesenfeld (BTW) sandpile under the height restriction is found to be non-Abelian. Using numerical results, we argue that the steady states of the sandpile are exactly the recurrent states of the BTW sandpile, but occur with nonuniform probabilities. A detailed analysis of the cluster size distributions indicates that the associated exponent values are likely to be different from those of the BTW sandpile. The other differences include that the drop number distribution decays as a power law, and the largest avalanche size grows as the fourth power of the system size.

Factors affecting condom use among fishers in Elmina fishing community in Ghana.

Although it is well known that low condom usage among fishers contributes to high HIV prevalence in fishing communities, little is known about the attitudes, beliefs, and behaviors of fishers when it comes to the use of condoms. This article is a follow-up to a cross-sectional study that used a mix-method design for data collection and analysis to examine the connection between mobility and the risk of contracting HIV among 385 fishers in the Elmina fishing community of Ghana. The Health Belief Model is utilized in the discussions to analyze attitudes and actions toward condom use among the fishers in Elmina. Over 40% of respondents who said they had intercourse in the previous year did not use condoms. The results show that male fishers are more likely than female fishers to use condoms during sexual activity, and younger fishers are more likely to use condoms than older fishers. More condoms were used by educated fishers than by less educated or uneducated fishers. According to the study, female fishers use less condoms than male fishers since they are unable to convince their partners to use them when they refuse to. Additionally, the findings show that slightly more than one in 10 respondents did not use condoms because they believed their sexual partner to be attractive and unlikely to carry any sexual infection. There is a general low perception of HIV susceptibility and severity resulting in the low condom usage among the fisherfolks according to the results. The article urges civil society organizations in the study area to investigate ways to incorporate the provision of free condoms to fishers and at the numerous fishing destination sites along the coast of Elmina. The regular use of condoms in Elmina and the nearby fishing areas should also be emphasised through this outreach or mobile HIV service outlets.

The new ecotourists of the 21st century: Brunei as a case study

Literature often describes the archetypical ecotourists as well-educated, and financially secure, coming from the “Western” Baby Boomer with strong convictions on the need for the conservation of nature and indigenous cultures. Today, traveling is made affordable for the mass coming from diverse nationalities, particularly of the younger generation, who are eager to experience disappearing cultures and nature. Although they appear to share traits of the ecotourists, are they truly the younger generations of ecotourists or do they seek out similar destination sites but for different reasons? Our research is the first attempt to answer this question. The paper aims to redefine the archetypical ecotourists in a market dominated by generations X, Y, and Z. The study involved survey questionnaires administered to 237 respondents living in Brunei coming from multiple generations comparing their attitudes, travel motivations, interests, and behaviour. A stratified-convenience sampling method was used to distribute the questionnaire to capture equal numbers of respondents in the three different generation groups. The data reveals some degree of incongruency between the younger generations of ecotourists and of the old archetypes. We found that the new ecotourists deviate in ideology and value. The new ecotourists are more inclined towards hedonism, social approval and popular culture. The differences in archetype have implications for tourism planning in general, and ecotourism in particular.

Techno-Economic Assessment of Large-Scale Green Hydrogen Logistics Using Ammonia As Hydrogen Carrier: Comparison to Liquified Hydrogen Distribution and In Situ Production

Green hydrogen plays a key role in decarbonizing the economy. However, the best conditions for producing it are often far from consumption places. This work compares three alternatives for large-scale green hydrogen distribution based on the levelized cost of hydrogen (LCOH): the use of green ammonia as a hydrogen carrier, the use of liquid hydrogen, and on-site production. All of the alternatives include production, packing, transport, and unpacking of hydrogen. Results show that liquid hydrogen outperforms the other alternatives in most cases. Only if the renewable electricity price in the destination site and hydrogen demand are low enough does on-site production become attractive. A demand of 1 MtH2/y leads to a LCOH equal to 5.14 USD/kgH2 when imported by ship as liquid hydrogen from 7,200 km away and considering electricity prices of 40 USD/MWh in the production site and 100 USD/MWh in the destination. Analogously, LCOH is 9.01 USD/kgH2 when produced in situ and 10.25 USD/kgH2 using ammonia as a hydrogen carrier. The ammonia alternative is attractive if ammonia is the desired good at the destination, or when it does not matter to import any of both fuels from the levelized cost of energy viewpoint. Blue hydrogen LCOH is estimated to be 65% cheaper than green hydrogen under similar scenarios.

Local environment drives rapid shifts in composition and phylogenetic clustering of seagrass microbiomes

Plant microbiomes depend on environmental conditions, stochasticity, host species, and genotype identity. Eelgrass (Zostera marina) is a unique system for plant–microbe interactions as a marine angiosperm growing in a physiologically-challenging environment with anoxic sediment, periodic exposure to air at low tide, and fluctuations in water clarity and flow. We tested the influence of host origin versus environment on eelgrass microbiome composition by transplanting 768 plants among four sites within Bodega Harbor, CA. Over three months following transplantation, we sampled microbial communities monthly on leaves and roots and sequenced the V4–V5 region of the 16S rRNA gene to assess community composition. The main driver of leaf and root microbiome composition was destination site; more modest effects of host origin site did not last longer than one month. Community phylogenetic analyses suggested that environmental filtering structures these communities, but the strength and nature of this filtering varies among sites and over time and roots and leaves show opposing gradients in clustering along a temperature gradient. We demonstrate that local environmental differences create rapid shifts in associated microbial community composition with potential functional implications for rapid host acclimation under shifting environmental conditions.

LCA of virgin and recycled materials to assess the sustainability of paved surfaces in agricultural environment

The construction sector is currently characterized by high raw material consumption but also by the production of high volume of wastes, mostly constituted by construction and demolition wastes that could be valorized promoting the use of recycled aggregates in substitution of raw aggregates. A promising application for recycled aggregates is for the realization of rural roads and pavements. The agricultural context, characterized by particular type of traffic and need to balance performance and integration with the environment, is suited for the use of these materials for paved surfaces since it can promote, in several cases, the adoption of rural circular processes internal to the farm. However, if on one hand the adoption of recycled aggregates could increase the sustainability of the sector, on the other it could increment the environmental loads if the whole process is not properly organized. For instance, the negative effects of transportation operations can cancel the environmental benefits if high distances between the production and the destination sites are present. This work reports the results of the Life Cycle Assessment (LCA), from cradle-to-gate, of four different construction aggregate classes that can be used for the realization of rural roads, pavements and forecourts, and paved areas in agricultural environment. The first three materials are recycled aggregates produced by the recycling processes of construction and demolition waste and the fourth type refers to gravel aggregates produced from natural resources. The Life Cycle Assessment was realized using site-specific primary data from the local territorial context and paying particular attention to transportation-related impacts, land use, avoided landfill and preservation of non-renewable resources. The results of the work clearly show that the environmental impacts in both scenarios of recycled aggregates are lower than the virgin aggregate scenario. In fact, considering the midpoint categories, the recycled materials proved to be more virtuous in almost all the indicators, with the exception of the marine eutrophication. The most significant gap between virgin and recycled materials has been in global warming and marine and freshwater eco-toxicity.

Characteristics of compensated mental disorders caused by overwork among drivers and non-drivers in the Japanese trucking industry

This study examined the characteristics of occupational mental disorders among those involved in the transport and postal activities in the trucking industry. We examined 237 out of 3,517 cases of occupational mental disorders, compensated between the fiscal years 2010 and 2017. An assessment was made for sex, "life-or-death" status at compensation, age at the onset and suicide, the diagnosis according to the International Classification of Diseases, Tenth Revision, and other factors regarding occupational compensation. The participants were divided into two groups: truck drivers and non-truck drivers. Men accounted for approximately 90% of the cases. Depressive episode (F32) was the most common diagnosis in drivers and non-drivers, thus constituting 65 out of 149 and 48 out of 88 cases, respectively. The next most common type of mental disorder was adjustment disorders (F43.2), with 34 out of 149 drivers and 24 out of 88 non-drivers reporting them. Furthermore, the majority of drivers that had posttraumatic stress disorder (24 out of 27 cases) reported that they "suffered a serious illness or injury" and "experienced or witnessed a terrible accident or disaster." Occupational disasters due to long working hours were 52.4% for drivers and 73.9% for non-drivers. A total of 30.8% of the drivers reported working long hours since they joined the company. Drivers' long working hours entail waiting at the origin and cargo destination site, handling cargo, and incidental tasks other than driving. Thus, the reduction in work hours regarding these tasks needs to be a fundamental goal, and measures that include mental health care for accidents and miserable experiences must be implemented. However, long working hours for non-drivers are likely linked to job expansion/increase and reassignment/relocation. These findings highlight that to prevent overwork-related mental disorders, appropriate actions should be taken considering different sources of exposure for drivers or non-drivers.

English

This review paper assesses the role of tour operators towards sustaining ecotourism in Tanzania. The motive behind it is based on the argument that tour operators have an important role within the ecotourism multi-stakeholder. However, little has been documented on how best to engage them for sustainable ecotourism. Thus, this paper provides a concise overview of the relevant literature, highlighting existing knowledge and gaps for prospective future research. In addition to the literature review and methods, the result section of the paper is organized in such a way that it elaborates on key concepts and provides the setup and organization of tour operators. As a core part of the review, this study underlined four key roles of tour operators towards sustainable ecotourism: their involvement in planning, development, promotion, and implementation of ecotourism products. The study concluded that ecotourism supporting and regulating machinery must work closely and strategically with tour operators at the individual level or through their existing tourism associations in order to ensure that those four identified areas are effectively and efficiently carried out, not only to enhance their business but also to conserve and market the destination sites and contribute to the country’s revenue.   Key words: sustainable ecotourism, tour operators, Tanzania.

Trophic ecology and length-weight relationship of Hypoatherina temminckii (Bleeker, 1854) in the seagrass ecosystem of Semak Daun Island, Kepulauan Seribu

Semak Daun Island is commonly used as a tourist destination site in the Kepulauan Seribu Marine National Park. Seagrass beds are found along the coast of this small island and have an essential role as shelter and feeding areas for various aquatic biotas, such as small-sized fishes of Samoan Silverside, Hypoatherina temminckii. Samoan silverside is usually used as bait in the tuna fishery. The present study aimed to determine growth pattern, diet composition, trophic level, guild, and feeding strategy of Samoan silverside in the seagrass ecosystem of the Semak Daun Island. Fish samples were captured using seine net monthly from February 2018 to March 2019. A total of 1,481 H. temminckii were collected, and all were juvenile. Results indicate that juveniles of Samoan silverside feed mainly on zooplankton and shows specialist predator as its feeding strategy. Moreover, this species occupies trophic levels ranging from 3.00-3.99 and exhibits a positive allometric growth pattern. Thus, the current study confirms that the seagrass ecosystem of the Semak Daun Island is the nursery and feeding grounds for the juvenile of Samoan silverside.

Binding Networks Identify Targetable Protein Pockets for Mechanism-Based Drug Design.

The human genome codes only a few thousand druggable proteins, mainly receptors and enzymes. While this pool of available drug targets is limited, there is an untapped potential for discovering new drug-binding mechanisms and modes. For example, enzymes with long binding cavities offer numerous prerequisite binding sites that may be visited by an inhibitor during migration from a bulk solution to the destination site. Drug design can use these prerequisite sites as new structural targets. However, identifying these ephemeral sites is challenging. Here, we introduce a new method called NetBinder for the systematic identification and classification of prerequisite binding sites at atomic resolution. NetBinder is based on atomistic simulations of the full inhibitor binding process and provides a networking framework on which to select the most important binding modes and uncover the entire binding mechanism, including previously undiscovered events. NetBinder was validated by a study of the binding mechanism of blebbistatin (a potent inhibitor) to myosin 2 (a promising target for cancer chemotherapy). Myosin 2 is a good test enzyme because, like other potential targets, it has a long internal binding cavity that provides blebbistatin with numerous potential prerequisite binding sites. The mechanism proposed by NetBinder of myosin 2 structural changes during blebbistatin binding shows excellent agreement with experimentally determined binding sites and structural changes. While NetBinder was tested on myosin 2, it may easily be adopted to other proteins with long internal cavities, such as G-protein-coupled receptors or ion channels, the most popular current drug targets. NetBinder provides a new paradigm for drug design by a network-based elucidation of binding mechanisms at an atomic resolution.

(Re)constructing Ageing Futures: Insights from Migration in Asia and Beyond

This special issue examines how older adults anticipate and manage their futures through migration. Although ageing is often associated with decline towards the end-of-life, it is still a life stage where (the lack of) planning for the future can profoundly impact the life outcomes of older adults and their caregivers. This collection illustrates different ways migration can impact ageing. For some, perceptions and depictions of the future lead older adults to turn to migration to improve their prospects of ageing well although they continue to face constraints while ageing abroad. For others, the migration of younger family members exacerbates the stress of eldercare felt by non-migrant caregivers. Collectively, the papers focus on how countries in Asia function as source and destination sites for ageing-related migration, while also forging transnational connections with the Global North. Focusing on ageing futures allows us to link the current and future lives of migrants and non-migrants, across generations and space.

Push and Pull Factors Influencing Destination Satisfaction For Sustainable Cultural Heritage Tourism Business Model: The Case Of Intramuros

Intramuros is one of the country’s acknowledged premier Cultural Heritage Tourism (CHT) destination site. With the objective of formulating a CHT model toward destination satisfaction and loyalty, the study assessed its destination attributes from the perspectives of the visitors through the PUSH and PULL Framework. It employed a mixed quantitative and qualitative methods using a researcher-made survey questionnaire administered using purposive sampling to 305 visitors. The findings were also examined and justified through a Focused Group discussion (FGD) among different tour operators within the Intramuros area.
 
 Intramuros CHT visitors are predominantly female, young; single; living within Metro Manila; with income up to P500,000 and below; Bachelor’s Degree holder and student/employee or professional; has visited it more than once together with friends, partner and family; for holiday and leisure and family togetherness; and came to know of Intramuros through the Internet and word of mouth; with trip of less than 24 hours; using either his personal car or public transport as mode of transportation. The push factor of “seeking relaxation” and the pull factor of “Cultural Heritage Features” had the strongest influence on levels of satisfaction accounting for 90 per cent of the visitors who signified their intention to go back and recommend the site to other tourists; although there are significant differences of level of satisfaction among them when they are grouped according to their profile.The study found moderate and positive relationships between push and pull factors and the attributes of the heritage site and the overall satisfaction of the visitors. Findings of the study were used to craft a Cultural Heritage Tourism Business Model for Customer Satisfaction and Customer Loyalty for Intramuros.

Smart Specialization in Australia: Between Policy Mobility and Regional Experimentalism?

abstract This article describes and analyzes the transfer of smart specialization (S3) from Europe, where it originated, to Gippsland, Australia. It identifies factors that are likely to enhance and, on the other hand, diminish the contribution of S3 to development in this region, and, more generally, to peripheral regions around the world. The policy mobility literature provides the analytical framework. It is used to explore how the validity of assumptions that underlie the efficacy of S3, in a destination site, and the institutional and political factors that must be accounted for through adaptation and reflexive policy learning, impact on the viability of policy transfer. This discussion demonstrates the links between geography, and entrepreneurship and innovation, and the challenges of linking the originally more or less homogenous framework to one concerned with development in heterogenous regions. An action research, constructivist approach is adopted. It yields fine-grained ethnographic data that reflects the importance, for effective evaluation of such transfer, of conceiving of a region as a relational space, where social interaction and connectivity drive and define the nature of change. The concomitant focus on process reveals that the intertemporal interchange between the means and ends of policy makers, must be carefully observed before proceeding to ex post evaluation of outcomes. Consequently, the article adds to the theoretical understanding of the complex processes involved in transferring regional policy approaches across spatial contexts. It provides valuable insights relevant to economic geographers, scholars, and practitioners concerned with regional development and innovation policy, and those exploring concepts and ideas associated with the policy mobility literature.

The effect of quantum noise on algorithmic perfect quantum state transfer on NISQ processors

Quantum walks are an analog of classical random walks in quantum systems. Quantum walks have smaller hitting times compared to classical random walks on certain types of graphs, leading to a quantum advantage of quantum-walks-based algorithms. An important feature of quantum walks is that they are accompanied by the excitation transfer from one site to another, and a moment of hitting the destination site is characterized by the maximum probability amplitude of observing the excitation on this site. It is therefore prospective to consider such problems as candidates for quantum advantage demonstration, since gate errors can smear out a peak in the transfer probability as a function of time, nevertheless leaving it distinguishable. We investigate the influence of quantum noise on hitting time and fidelity of a typical quantum walk problem - a perfect state transfer (PST) over a qubit chain. We simulate dynamics of a single excitation over the chain of qubits in the presence of typical noises of a quantum processor (homogeneous and inhomogeneous Pauli noise, crosstalk noise, thermal relaxation, and dephasing noise). We find that Pauli noise mostly smears out a peak in the fidelity of excitation transfer, while crosstalks between qubits mostly affect the hitting time. Knowledge about these noise patterns allows us to propose an error mitigation procedure, which we use to refine the results of running the PST on a simulator of a noisy quantum processor.

Geographic Factors for Managing Cruise Ship Destination Port to Attraction Passenger Transfer in the Caribbean Region

Abstract. The Cruise Line industry (CLI) is working on plans to recover from the economic impacts of COVID-19. Along with the expected benefits of a post COVID19 surge in cruise tourism, destination ports have an opportunity to mitigate potential impacts that come with the tourist economy. In this study, we expand on our previous work on four CLI destination sites (two in the Caribbean and two meso-American) to a larger regional study area in the Caribbean Sea and investigate the sustainability of destination marine infrastructure and near port transportation resilience. Twenty- Eight destinations were analyzed in the study. All the CLI destinations ports in the study are considered mature for cruise tourism and have tourist attractions of interest (including historic, natural, shopping, and other areas with sociocultural authenticity), which can be reached during a one day ship visit. An analysis of the marine traffic and geographic settings provides a more complete picture on key parameters that can potentially impact the commerce and livelihoods of local communities near destination ports. The results of the study also provide potential solutions for mitigating these impacts. As a baseline for fully operational cruise industry in the Caribbean Sea, the 2019 cruise year was analyzed since it was the last full year without impact from COVID-19. This paper offers a wider empirical view of CLI impacts on the Caribbean region once the industry resumes to full capacity following the COVID-19 pandemic, and it presents results and recommendations to build a framework for continued study of CLI sustainability.

The future of Wallace region in Lombok: the pristine natural resource under climatic and anthropogenic threat

Wallace region is mostly comprised of the southeast archipelagoes of Indonesia, namely West and East Nusa Tenggara. Lombok is a west border of the Wallace line which biologically delineate the distinguished fauna and climate in the eastern Indonesia. However, the pristine natural resource is under climatic and anthropogenic threat. A case study by means of a Descriptive method was conducted to identify any contradictive use of natural resource leading to environmental degradation, as well as to study ruination impact of climate uncertainty. Long term satellite images of Lombok from 1980’s up to the latest date were traced to identify any changes in land cover, land use and settlement. Climate data were analyzed to find its trend and forecast its potential impact on the environment. Overall, the results showed that the pristine environments, namely forests, hillocks and cliffs, particularly in tourism destination sites had been accordingly overburdened by contradictive use of resources. Lack of law enforcements in environmental protection was a key point to be addressed as a major factor resulted in losses of the most valuable value of Lombok natural scene. In addition, manmade disaster is becoming more frequent with climate change commonly accused. In conclusion, the future of the natural resource in Lombok would not be merely relied on world class facilities of tourism industry, but on to what extend effort to naturally sustain the beauty of natural scene, stop degrading the lands and be responsible to protect environment in line with regional development.

Cultural health capital and the stratification of reproduction in Czech and Spanish egg donation markets.

This article explores the ways that fertility clinics in the Czech Republic and Spain attract international fertility clients for fertility treatment involving egg donation. I draw upon a content analysis of 18 fertility clinics' advertising materials and 31 in-depth interviews with fertility professionals in the Czech Republic and Spain, and Canadian fertility travellers to show how clinics use cultural health capital (CHC) to persist as popular destination sites for fertility travellers. I argue that the use of evidence-based medicine and patient-centred care combined with bioracial discourses are strategies by which clinics create a culture of fertility care that is legible to white, middle-class, hetero travellers. My interviews with fertility patients who travelled to these sites show the ways in which CHC is interactional-I document how fertility travellers desire these specific practices that are both created for and marketed to them. By expanding the definition of CHC to show how fertility clinics market and fertility travellers expect a particular culture of fertility medicine, I elucidate the interactions between clinics and professionals that reinforce ideals of white motherhood and the stratification of reproduction.

Social Dominance Orientation in Agrarian Resources Accumulation in Coastal Area Indonesia

Intergroup contact influenced the adaptation capacity of Bugis ethnic in the economic system in the destination site. When they become the highest of social-rank than other ethnicities in livelihood strategies by land-accumulation, it becomes important to analyze the working of power from the ethnic-Social Domination Orientation (SDO) theoretical. The role of ethnic-SDO is studied with assessment determination in a sociocultural context in intergroup ethnic inequality. Moreover, decision making in framing becomes challenged to be assessed at the individual level because it is assumed would influence the individual to enhance the hierarchy in the middle of uncertainty outcomes. This study aims: (1) elucidate the structure of ethnic inequality in livelihood strategies by ethnic-SDO in Bugis ethnic; and (2) recognize the role of framing in decision making as influencing factors of ethnic-SDO. This study approach is qualitative, which involves 25 informants. Data showed that ethnic-SDO in Bugis’s economic activities comprised of power that enhancing-hierarchy evolved ethnic inequality by high between-ethnic group inequality (BGI) and within- ethnic group inequality (WGI) in land-accumulation. It is found that the framing of Bugis people regarding skills and attitudes owned by other ethnicities in the decision-making tends to risk-avoid that enhancing-hierarchy in economic activities at an individual level.

Is Gay Tourism More Than Tourism? A Case Study of Puerto Vallarta, MX

The reasons gay men seek out gay travel destinations has been well established in the literature. However, less research has been published on the consequences of that travel on the destinations themselves and the effect of gay tourism on the LGBTQ+ community as a whole. I use ethnographic research in Puerto Vallarta, Mexico, a popular international gay tourist destinations for American and Canadian gay men. I focus on how gay destinations are constructed as sites where members of the gay community can experience acceptance and inclusion and I ask the following questions, is this acceptance and inclusion dependent upon consumption? Are the tourist site and expectations for behavior in those sites oppressively normal? That is, does the site create a normative standard of behavior for gay tourists? Furthermore, while gay tourists may experience inclusion and a level of acceptance, how does gay tourism affect the destination site itself? Is this acceptance and inclusion problematized by larger systems of inequality such as class, gender, and race? Lastly, as members of a historically oppressed group, does and should gay tourism rise above its commodification to produce just, equitable relationships within and beyond the LGBTQ+ community including the environment?

Linking blue carbon ecosystems with sustainable tourism: Dichotomy of urban–rural local perspectives from the Philippines

Blue carbon ecosystems (BCEs) are linked to tourism industry either as the main destination site or as additional features. Achieving sustainable tourism in coastal areas warrants the inclusion of long-term BCE management and protection, hence, it is important to understand how tourism impacts these resources to better formulate apt strategies tailored to the individual contexts. In Busuanga Island, Philippines, where tourism industry depends highly on its coastal and marine resources, there is a gap in understanding the impacts of tourism on BCEs. Thus, this study aims to analyze communities’ perceptions of sustainable tourism and BCE services by comparing household survey results between urban (Coron) and rural (Busuanga) communities. Specifically, this work aims to determine residents’ perceptions of tourism impacts at the personal and community levels, to examine whether socio-demographic profiles, ecological consciousness, awareness of programs for sustainable tourism, and ecological protection drive these perceptions, and to compare these results in urban and rural settings. Results of this study indicate a distinctive difference between urban and rural perceptions; e.g., residents perceived highly of tourism benefits and impacts in Coron whereas fewer recognitions are observed in Busuanga. Correlations of locals’ awareness of BCE services with perceived environmental changes caused by tourism showed positive effects. Environment-related plans received high recognition in promoting sustainable tourism. Overall, locals’ perceptions of tourism and blue carbon ecosystems can be bundled together. This linkage could address future planning of sustainable tourism master plan at the municipal level particularly those towns that features coastal resources as their main tourism attractions.