Intensities Of Use Research Articles

Evaluating tourism scenarios within the limit of acceptable change framework in Barcelona

This article introduces an expanded Limit of Acceptable Change model, enhancing the traditional approach by incorporating various tourism scenarios and a broader range of indicators. This approach allows to gain a more comprehensive understanding and foresee the effects of diverse tourist profiles and intensities of use in Barcelona. It considers factors like motivation, origin, and accommodation type, and evaluates their effects on key sustainability indicators. The study reveals that significant shifts in tourism patterns are required to impact these indicators noticeably, emphasizing the need to consider both tourist numbers and typologies in sustainable tourism management. This approach equips destination planners with a valuable tool for strategic decision-making and long-term planning.

Multivariate analysis of herd structure and genetic resource indicators in seedstock beef cattle herds.

Genetic, environmental, technological and financial resources are used differently in cattle herds that participate in the same breeding programme. The percentages of calves sired by sires within their own herd or from external herds vary across herds, as do the intensities of use of reproductive biotechnologies. These divergences may be related to differences in the indicators of genetic performance for economic traits. The aim of this study was to determine the factors related to herd structure and genetic resource utilization that exert the greatest influence on the genetic merit of seedstock herds within a Nellore breeding programme. The database comprised 21 factors, along with genomic-enhanced expected progeny differences (GE-EPDs) for growth, reproductive and carcass traits, as well as a selection index of animals from 128 herds. By combining principal component analysis and cluster analysis, we were able to group the herds. We identified statistically significant differences (p < 0.05) in the mean values of the factors, GE-EPDs and genetic trends among the groups of herds. Differences in the percentage of sires from external herds and in sire age between the groups of herds were the factors most associated with differences in mean GE-EPDs and genetic trends. Using young sires from other herds or lineages is an effective strategy in animal breeding. By enhancing genetic variability, this approach does not only improve the genetic quality of herds but also accelerates genetic progress in desired traits over time. Therefore, to ensure the success of this strategy, it is crucial that seedstock herds undergo a thorough selection process aimed at maximizing the genetic potential of future generations of beef cattle.

Association of vaginal oestradiol and the rate of breast cancer in Denmark: registry based, case-control study, nested in a nationwide cohort

ObjectiveTo estimate the rate of breast cancer associated with use of vaginal oestradiol tablets according to duration and intensity of their use.DesignRegistry based, case-control study, nested in a nationwide cohort.SettingBased...

Associations Between Product Type and Intensity of Tobacco and Cannabis Co-use on the Same Day Among Young Adult Smokers: Smartphone-Based Daily-Diary Study.

Co-use of tobacco and cannabis is highly prevalent among young US adults. Same-day co-use of tobacco and cannabis (ie, use of both substances on the same day) may increase the extent of use and negative health consequences among young adults. However, much remains unknown about same-day co-use of tobacco and cannabis, in part due to challenges in measuring this complex behavior. Nuanced understanding of tobacco and cannabis co-use in terms of specific products and intensity (ie, quantity of tobacco and cannabis use within a day) is critical to inform prevention and intervention efforts. We used a daily-diary data collection method via smartphone to capture occurrence of tobacco and cannabis co-use within a day. We examined (1) whether the same route of administration would facilitate co-use of 2 substances on the same day and (2) whether participants would use more tobacco on a day when they use more cannabis. This smartphone-based study collected 2891 daily assessments from 147 cigarette smokers (aged 18-26 years, n=76, 51.7% female) during 30 consecutive days. Daily assessments measured type (ie, cigarette, cigarillo, or e-cigarette) and intensity (ie, number of cigarettes or cigarillos smoked or number of times vaping e-cigarettes per day) of tobacco use and type (ie, combustible, vaporized, or edible) and intensity (ie, number of times used per day) of cannabis use. We estimated multilevel models to examine day-level associations between types of cannabis use and each type of tobacco use, as well as day-level associations between intensities of using cannabis and tobacco. All models controlled for demographic covariates, day-level alcohol use, and time effects (ie, study day and weekend vs weekday). Same-day co-use was reported in 989 of the total 2891 daily assessments (34.2%). Co-use of cigarettes and combustible cannabis (885 of the 2891 daily assessments; 30.6%) was most commonly reported. Participants had higher odds of using cigarettes (adjusted odds ratio [AOR] 1.92, 95% CI 1.31-2.81) and cigarillos (AOR 244.29, 95% CI 35.51-1680.62) on days when they used combustible cannabis. Notably, participants had higher odds of using e-cigarettes on days when they used vaporized cannabis (AOR 23.21, 95% CI 8.66-62.24). Participants reported a greater intensity of using cigarettes (AOR 1.35, 95% CI 1.23-1.48), cigarillos (AOR 2.04, 95% CI 1.70-2.46), and e-cigarettes (AOR 1.48, 95% CI 1.16-1.88) on days when they used more cannabis. Types and intensities of tobacco and cannabis use within a day among young adult smokers were positively correlated, including co-use of vaporized products. Prevention and intervention efforts should address co-use and pay attention to all forms of use and timeframes of co-use (eg, within a day or at the same time), including co-use of e-cigarettes and vaporized cannabis, to reduce negative health outcomes.

Biologically Important Areas II for cetaceans within U.S. and adjacent waters – Hawaiʻi Region

In this assessment we incorporated published and unpublished information to delineate and score Biologically Important Areas (BIAs) for cetaceans in the Hawaiʻi region following standardized criteria. Twenty-six cetacean species have been documented in Hawaiʻi. Eleven odontocete species have distinct small populations resident to one or more island areas: rough-toothed dolphins, pantropical spotted dolphins, common bottlenose dolphins, spinner dolphins, short-finned pilot whales, false killer whales, pygmy killer whales, melon-headed whales, Blainville’s beaked whales, Cuvier’s beaked whales, and dwarf sperm whales. Eight species of mysticetes have been documented, although their occurrence and behavior are poorly understood, with the exception of breeding humpback whales and, more recently, common minke whales. Thirty-five BIAs were delineated or revised from the initial 2015 effort: 33 for small and resident odontocete populations and two for humpback whale reproductive areas. Hierarchical BIAs reflecting core areas of use or population-specific ranges were delineated for nine species. Reproductive watch list areas were designated for common minke whales in the main Hawaiian Islands (MHI) and humpback whales in the Northwestern Hawaiian Islands (NWHI); these areas did not meet the criteria for a BIA due to limited supporting information. All but three BIAs were in the MHI, reflecting the disparities in research effort between this region and the NWHI. Spatial extents of BIA boundaries ranged from 457 km2to 138,001 km2(median = 8,299 km2). Scores (range: 1-3) for Data Support and Boundary Certainty were moderate to high (mean = 2.40 and 2.43, respectively), while Intensity and Importance scores were slightly lower (mean = 1.94 and 1.89, respectively). Many of the Hawaiʻi species have been extensively studied over several decades; accordingly, this region ranks among the highest in terms of Data Support relative to other regions. BIAs presented here describe known ranges of small resident populations, intensities of use, and uncertainties in important areas for cetaceans in Hawaiʻi based on the best available data, and have also revealed knowledge gaps to guide future research efforts.

The role of Rare Earth Elements in the deployment of wind energy in Colombia

The deployment of renewable energy technologies will play a crucial role in the global transition to a low-carbon economy and ultimately in the fight against global warming. However, this transition could face important problems because most of those technologies rely on the steady supply of critical minerals. Colombia, thanks to its hydrological resources, has relied on the hydro­power for electricity generation. However, the government has implemented measures to back-up the energy system in draught periods and, consequently, fossil fuels-based plants have increased the market share and with these, CO2 emissions. This study assesses the mineral demand in Colombia in the period 2020-2050 for the rare earth elements embedded in the deployment of wind power technologies in four different climate policy scenarios in order to establish whether they could face geological bott­lenecks that could ultimately hamper the transition to a low-carbon economy. The Gigawatts (GW) of future capacity additions in the energy system are converted into tons of metal using published metal intensities of use and assumptions of Colombia’s technological pathway. Then, the cumulated mineral demand is compared against current mining production rates and geological reserves to establish geological bottlenecks. The results show that the reserves will not pose any threat to its transition. However, when compared to current mining rates, the mineral demand in 2050 could pose a problem for the supply of minerals. Finally, this study gives some policy recommendations that could be used to mitigate these issues, such as substitution, improved circular economy and sound technological choices.

Immigrant linguistic integration in the multilingual context of Montreal

Abstract We investigate the relative intensity of use of English and French at home for allophone immigrants in the Montreal metropolitan area. We find that the linguistic distances between immigrants’ mother tongues and English and French have an important impact on the relative intensities of use at home of the two Canadian official languages. However, immigrants whose mother tongues are closer to French than to English are relatively less likely to use an official language at home. We further investigate the role of spousal and other characteristics on the integration of immigrants. The results suggest that the home environment is an important factor contributing to the linguistic integration. Individuals exposed to an official language at home with their spouse have significantly higher rates of linguistic integration. Also, English is more attractive than French in the sense that immigrants with an Anglophone partner will have higher integration rates to English than those with a Francophone partner integrating to French.

Measuring Changes in Multimodal Travel Behavior Resulting from Transport Supply Improvement

Despite the desired transition toward sustainable and multimodal mobility, few tools have been developed either to quantify mode use diversity or to assess the effects of transportation system enhancements on multimodal travel behaviors. This paper attempts to fill this gap by proposing a methodology to appraise the causal impact of transport supply improvement on the evolution of multimodality levels between 2013 and 2018 in Montreal (Quebec, Canada). First, the participants of two household travel surveys were clustered into types of people (PeTys) to overcome the cross-sectional nature of the data. This allowed changes in travel behavior per type over a five-year period to be evaluated. A variant of the Dalton index was then applied on a series of aggregated (weighted) intensities of use of several modes to measure multimodality. Various sensitivity analyses were carried out to determine the parameters of this indicator (sensitivity to the least used modes, intensity metric, and mode independency). Finally, a difference-in-differences causal inference approach was explored to model the influence of the improvement of three alternative transport services (transit, bikesharing, and station-based carsharing) on the evolution of modal variability by type of people. The results revealed that, after controlling for different socio-demographic and spatial attributes, increasing transport supply had a significant and positive impact on multimodality. This outcome is therefore good news for the mobility of the future as alternative modes of transport emerge.

Linguistic Distance, Languages of Work and Wages of Immigrants in Montreal

We use the Levenshtein linguistic distance measure to explore the question of whether the distance between an immigrant’s mother tongue and a Canadian official language (English or French) has an impact on his/her economic integration into the labor market. Using microdata from the master files of the 2001 and 2006 Canadian censuses and from the 2011 National Household Survey, we investigate the relationship between linguistic distance and the intensity of use of English and French at work in the Montreal metropolitan area. That region is characterized by the presence of sizeable French- and English-speaking communities, as well as by a large number of immigrants from a wide variety of linguistic backgrounds. Those elements of linguistic diversity interact in the environment of English being the lingua franca. We find that linguistic distances between immigrants’ mother tongues and English and French have an important impact on the relative intensities of use of the two Canadian official languages at work. We further investigate the role of the languages used at work on the earnings of immigrants by estimating earnings functions. We find that the use of both French and English is remunerated positively in the labor market, but that using English at work has a larger impact on earnings.

COVID-19: Technology, Social Connections, Loneliness, and Leisure Activities: An International Study Protocol

Drawn from the stress process model, the pandemic has imposed substantial stress to individual economic and mental well-being and has brought unprecedented disruptions to social life. In light of social distancing measures, and in particular physical distancing because of lockdown policies, the use of digital technologies has been regarded as the alternative to maintain economic and social activities. This paper aims to describe the design and implementation of an online survey created as an urgent, international response to the COVID-19 pandemic. The online survey described here responds to the need of understanding the effects of the pandemic on social interactions/relations and to provide findings on the extent to which digital technology is being utilized by citizens across different communities and countries around the world. It also aims to analyze the association of use of digital technologies with psychological well-being and levels of loneliness. The data will be based on the ongoing survey (comprised of several existing and validated instruments on digital use, psychological well-being and loneliness), open for 3 months after roll out (ends September) across 11 countries (Austria, France, Germany, India, Malta, Portugal, Romania, Spain, Turkey, and UK). Participants include residents aged 18 years and older in the countries and snowball sampling is employed via social media platforms. We anticipate that the findings of the survey will provide useful and much needed information on the prevalence of use and intensities of digital technologies among different age groups, gender, socioeconomic groups in a comparative perspective. Moreover, we expect that the future analysis of the data collected will show that different types of digital technologies and intensities of use are associated with psychological well-being and loneliness. To conclude, these findings from the study are expected to bring in our understanding the role of digital technologies in affecting individual social and emotional connections during a crisis.

HUMAN TRAMPLING EFFECT ON BENTHIC FAUNA OF SANDY BEACHES WITH DIFFERENT INTENSITIES OF USE IN RIO DE JANEIRO, BRAZIL

About 75% of the world’s shoreline is composed of beach environments. Among them, the sandy beach is a familiar environment and used for tourism and recreation. The organisms that live in these environments, as polychaetes, crustaceans and mollusks, are almost unknown by people because they live buried. Thus, many time people could cause damage to these organisms without their own knowledge. Trampling is one of the human-induced impacts to those organisms, destroying their bodies or even dispelling them. Focused on this behavior, this research aims to simulate trampling on two sandy beaches and to observe a real scenario of recreation on weekends and during the week during summer and winter seasons in the Rio de Janeiro state, Brazil. This study verified the changes occurring mainly in the faunal density of these two beaches with different intensities of use, in the predefined situations. Samples were collected during four months, on the second half of year, using simulated treatments and in another two months simple observation of the behavior of tourists was also performed. The simulated treatments did not cause significant changes in any collection except two. One of them was possibly a sampling artifact, which may be due to a low level of impact. The samples on the winter months also did not show significant changes, but the summer samples showed a large decrease in density of organisms during the weekend compared to during the week, probably related to the high intensity of human activity. As this study aimed to verify changes or impacts in organisms at up to 20 cm of depth, we concluded that only high impact activities could affect drastically the faunal density, as observed during the summer season at weekends on the study.

Estimating the intensity of use by interacting predators and prey using camera traps.

Understanding how organisms distribute themselves in response to interacting species, ecosystems, climate, human development and time is fundamental to ecological study and practice. A measure to quantify the relationship among organisms and their environments is intensity of use: the rate of use of a specific resource in a defined unit of time. Estimating the intensity of use differs from estimating probabilities of occupancy or selection, which can remain constant even when the intensity of use varies. We describe a method to evaluate the intensity of use across conditions that vary in both space and time. We demonstrate its application on a large mammal community where linear developments and human activity are conjectured to influence the interactions between white-tailed deer (Odocoileus virginianus) and wolves (Canis lupus) with possible consequences on threatened woodland caribou (Rangifer tarandus caribou). We collect and quantify intensity of use data for multiple, interacting species with the goal of assessing management efficacy, including a habitat restoration strategy for linear developments. We test whether blocking linear developments by spreading logs across a 200-m interval can be applied as an immediate mitigation to reduce the intensities of use by humans, predator and prey species in a boreal caribou range. We deployed camera traps on linear developments with and without restoration treatments in a landscape exposed to both timber and oil development. We collected a three-year dataset and employed spatial recurrent event models to analyse intensity of use by an interacting human and large mammal community across a range of environmental and climatic conditions. Spatial recurrent event models revealed that intensity of use by humans influenced the intensity of use by all five large mammal species evaluated, and the intensities of use by wolves and deer were inextricably linked in space and time. Conditions that resist travel on linear developments had a strong negative effect on the intensity of human and large mammal use. Mitigation strategies that resist, or redirect, animal travel on linear developments can reduce the effects of resource development on interacting human and predator-prey interactions. Our approach is easily applied to other continuous time point-based survey methodologies and shows that measuring the intensity of use within animal communities can help scientists monitor, mitigate and understand ecological states and processes.

Visitor monitoring in protected areas: an approach to Natura 2000 sites using Volunteered Geographic Information (VGI)

ABSTRACTThis paper analyses visitor monitoring and the public use of protected areas using volunteered geographic information (VGI) as a source of big data and, as the object of study, the Ebro Delta Natura 2000 site (west Mediterranean basin). Over 5,000 voluntarily recorded tracks spread over 10 years have been analysed, showing a predominance of cycling activities on trails of up to 50 km in length. Using cluster analysis and a hotspot approach, we found that the highest intensities of use are concentrated in less than 1% of the area studied, while a high dispersion of track start/finish points suggests low but scattered pressure all over the site. Spatial analysis reveals a number of spatial interactions, including the use of official trails, trespassing on reserves and potential nuisance to birdlife. This information is useful for site managers and helps them design sustainable practices. By applying the same analysis using VGI and data mining to other Natura 2000 sites, comparisons can be made and thus provide valuable assessment regarding visitor monitoring and public use patterns for the largest network of protected areas in the world.

The role of teacher capacity and instructional practice in the integration of educational technology for emergent bilingual students

This mixed methods study examines the extent to which the use, and intensity of use, of educational technology is associated with improved academic outcomes for English language learners (ELLs) in both English/Spanish bilingual and traditional English-only classrooms. We also explore the role of teacher capacity and practice in integrating educational technology by student population and instructional setting across six schools serving a student population of predominately low-income ELLs. Building on limited prior work on technology integration with elementary school ELLs, the analysis draws on district administrative data, teacher surveys, classroom observations, and teacher interviews. In econometric analyses of academic outcomes associated with exposure to varying intensities of technology use, we identified positive associations of technology use in reading, starting at around 40 min of weekly use in bilingual classrooms versus 1 h of weekly use in traditional classrooms. While the average reading effect size topped out at 0.20 for students with 2 h of weekly technology use in reading in traditional classrooms, the reading effect size continued to rise in bilingual classrooms to over 0.50 for students in classrooms using technology for 3 h a week in reading. We also found that technology use in reading—where teachers were observed more frequently using blended instructional strategies—was more effective for students in bilingual classes than technology use in math. Our findings suggest that alignment of technology with constructivist teaching strategies, which connect student learning to culturally relevant experiences and provide opportunities for interactivity and collaboration, is key to transforming the learning process and outcomes of emergent bilingual students.

Caracterización Ecológica Cuantitativa De La Vegetación En Sitios De La Costa Central Del Golfo En El Desierto Sonorense

The Central Gulf Coast, subdivision of the Sonoran Desert, requires urgent actions to ecological restoration and development of sustainable alternatives to promote the generation of economic benefits in a manner consistent with the conservation of natural resources. Four sites were selected in the coastal region of the municipality of Hermosillo between 28°42'04" and 28°52'24" North and 111°45'39" and 111°56'48" West. Sites are representative of the various plant associations with variants in soil structure, topography and intensities of use. General plant diversity, plant density, height and canopy cover from shrub/tree plants, and basal cover from herbaceous plants were evaluated at each site. Species richness indices, equity and diversity among plant communities were compared. Major plant associations were identified as 1) Sarcocaulescent scrub, 2) Halophytes Communities, 3) Arbo-crasicaulescent scrub, and 4) Arbo-suffrutescent scrub. Sixty five plant species in 26 families were identified. Families with higher number of species were Cactaceae (12), Euphorbiaceae (7), Fabaceae (7) and Malvaceae (5). Species richness and diversity indices indicated differences between sites. Values of relative importance are identified among plant associations for subsequent analysis of productive and ecological trends as well as for the assessment of wildlife diversity and population parameters associated to each condition of the vegetation. This work is aimed to generate integral models for identifying feasibility and setting priorities for ecological restoration practices in the Sonoran Desert.

Initial micromorphological results from Liang Bua, Flores (Indonesia): Site formation processes and hominin activities at the type locality of Homo floresiensis

Liang Bua, a karstic cave located on the island of Flores in eastern Indonesia, is best known for yielding the holotype of the diminutive hominin Homo floresiensis from Late Pleistocene sediments. Modern human remains have also been recovered from the Holocene deposits, and abundant archaeological and faunal remains occur throughout the sequence. The cave, the catchment in which it is located and the gross aggradational phases of the sediment sequence have all been subject to a great deal of scientific scrutiny since the discovery of the holotype of H. floresiensis in 2003. A recent program of geoarchaeological research has extended analyses of the site’s deposits to the microstratigraphic (micromorphological) level. The stratigraphic sequence in the cave is well defined but complex, comprising interstratified sediments of diverse lithologies and polygenetic origins, including volcanic tephras, fine-grained colluvium, coarse autogenic limestone gravels, speleothems and anthropogenic sediments, such as combustion features. The sedimentological and chemical heterogeneity suggest that processes of site formation and diagenesis varied markedly through time, both laterally and vertically. We present initial results from samples collected in 2014 from an excavation area near the rear of the cave, which yielded radiocarbon ages from charcoal that fill an important temporal gap in the chrono-stratigraphic sequence of previously excavated areas of the site. The results indicate marked changes in site environment and hominin activity during the Late Pleistocene, relating primarily to the degree to which the cave was connected to the hydrogeological system and to the varying intensities of use of the cave by hominins. Importantly, we identify anthropogenic signs of fire-use at the site between 41 and 24 thousand years ago, most likely related to the presence of modern humans.

Evaluating distributional shifts in home range estimates.

A variety of methods are commonly used to quantify animal home ranges using location data acquired with telemetry. High-volume location data from global positioning system (GPS) technology provide researchers the opportunity to identify various intensities of use within home ranges, typically quantified through utilization distributions (UDs). However, the wide range of variability evident within UDs constructed with modern home range estimators is often overlooked or ignored during home range comparisons, and challenges may arise when summarizing distributional shifts among multiple UDs. We describe an approach to gain additional insight into home range changes by comparing UDs across isopleths and summarizing comparisons into meaningful results. To demonstrate the efficacy of this approach, we used GPS location data from 16 bighorn sheep (Ovis canadensis) to identify distributional changes before and after habitat alterations, and we discuss advantages in its application when comparing home range size, overlap, and joint-space use. We found a consistent increase in bighorn sheep home range size when measured across home range levels, but that home range overlap and similarity values decreased when examined at increasing core levels. Our results highlight the benefit of conducting multiscale assessments when comparing distributions, and we encourage researchers to expand comparative home range analyses to gain a more comprehensive evaluation of distributional changes and to evaluate comparisons across home range levels.

INTERNET INALÁMBRICO COMO HERRAMIENTA DE ACCESO GRATUITO A LA INFORMACIÓN EN LA UNIVERSIDAD PÚBLICA

Es evidente que es necesario cambiar el modelo educativo actual y evolucionar hacia otro modelo donde la formación universitaria atienda adecuadamente a la demanda existente pero con calidad. Ante estas necesidades, las Tecnologías Inalámbricas pueden ser uno de los elementos claves que ayuden a las transformaciones requeridas. Así lo han entendido muchas universidades peruanas que con distintas intensidades de uso de la Web ofertan asignaturas, cursos y carreras totalmente virtuales. Algunos consideran que la inserción de las Tecnologías Inalámbricas plantean que remplazan el papel del profesor, lo que no es verdad, pues con ellas el profesor tiene que jugar un papel importante como orientador, para que los estudiantes no se pierdan en la búsqueda de información, en el manejo y utilización de materiales didáctico, guiándolos para que realicen el mayor esfuerzo de análisis e interpretación y no sólo la mecánica de copiar y pegar. En este contexto el presente artículo busca destacar la importancia de la utilización de las Tecnologías Inalámbricas para optimizar el proceso de enseñanza-aprendizaje.

From physiology to space use: energy reserves and androgenization explain home‐range size variation in a woodland rodent

This study tested the relationships between both individual-level and predation-risk factors and the size of two home-range regions (HRR), defined as areas of different intensities of use. We have expanded on previous home-range studies by testing the effects of two previously ignored individual-level factors: androgenization and energy reserves (body fat). Location data were collected for wild individuals of Apodemus sylvaticus using the novel method of implanted PIT tags and mobile recording stations. A total of 68 home ranges were estimated using kernel density estimation. Home ranges were split into two regions (HRR): the 'core', representing the most intensively used areas, and 'periphery' regions. Body mass, body fat, sex, anogenital distance (AGD) (a proxy for androgenization) and the proportion of HRR, covered by antipredatory features (shrubs and fallen trees), were tested for their relationship with the size of core and periphery HRRs. Models were constructed for each HRR for three seasons: nonbreeding season (NBS), early and late breeding seasons (LBSs), to account for seasonal variation in behaviour associated with changes in food abundance and reproductive cycles. Body fat had a negative relationship with periphery size and an interaction with sex on core size in the early breeding season (EBS). Body mass also had a significant interaction with sex on core size in the EBS. Androgenization has a strong effect on home range size in both sexes: AGD had a positive relationship with both HRRs for males in the LBS and females in the NBS. Males had larger peripheries than females in both early and LBSs. Habitat features that reduce predation risk explain HRR size throughout the breeding period. This study emphasizes the importance of embracing natural complexity to gain insight into the drivers of space use behaviour; the consideration of individual and ecological factors, the recognition of the species-specific selective pressures that seasonal change presents for each sex and the identification of biologically meaningful home range areas will help advance the field.

A simple mineral market model: Can it produce super cycles in prices?

This paper develops a stylized supply–demand model for a mineral/nonrenewable commodity. It embodies important distinctions between short-run and long-run mineral supply and the derived demand for minerals as intermediate goods in production sectors with differing intensities of use. This framework is used to address the question: under what conditions might one expect to observe super cycles (i.e. cycles with a period of 20–70 years) in minerals prices? A plausible time path for GDP growth and the structural transformation that accompanies economic development in an emerging region is specified. Using these drivers and reasonable supply and demand parameters, price dynamics are simulated. The result is an asymmetric price cycle with a peak price that is about 250% above trend and an expansion phase that lasts for about 20 years. Thus, this simple model is capable of producing a single cycle with a frequency and amplitude in the range estimated in the empirical literature on super cycles. As other regions reach the development ‘take-off' phase, additional super cycles should emerge.