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PubMed1998

Resource-Allocation Strategies: A Verbal Protocol Analysis.

The current study examined the strategies used by people to solve resource-allocation problems. Verbal protocols were recorded as participants provided meal choices for seven consecutive days with limited resources available to spend on meals and with daily constraints imposed on meal consumption. None of the participants incorporated the established mathematical procedures (i.e., Linear Programming) to arrive at the optimum number of meals possible in a week. However, the strategies they did use enabled them to achieve meal totals on average at 94% of this optimal amount. A few participants attempted to first solve the maximum meals possible in a week before scheduling this solution across the seven days (solve-and-schedule strategy), but the majority of participants simply selected meals on a day-to-day basis while checking resource availability each day to allow for full resource consumption (consume-and-check strategy). The findings of this study provide a preliminary step toward understanding how people make intuitive resource-allocation decisions. Copyright 1998 Academic Press.

Journal Article↗

PubMed2002

Coexistence in MacArthur-style consumer-resource models.

The nature of and conditions for permanent coexistence of consumers and resources are characterized in a family of models that generalize MacArthur's consumer-resource model. The generalization is of the resource dynamics, which need not be of Lotka-Volterra form but are subject only to certain restrictions loose enough to admit many resource dynamics of biological interest. For any such model, (1) if there is an interior equilibrium, then it is globally attracting, else some boundary equilibrium is globally attracting-thus permanent coexistence is coexistence at a globally attracting equilibrium; (2) there is an interior equilibrium if and only if for any species, the equilibrium approached in the absence of that species and the presence of the others is invasible by that species--thus permanent coexistence is equivalent to mutual invasibility; (3) for resources without direct interactions, the conditions for permanent coexistence of the consumers admit an instructive formulation in terms of regression statistics. The significance and limitations of the models and results are discussed.

Animals↗

PubMedDate not supplied

Determinants of resource utilization for patients admitted for evaluation of acute chest pain.

OBJECTIVE: To identify determinants of resource utilization among patients with suspected acute myocardial infarction. DESIGN: Prospective cohort study, with prospective collection of detailed clinical data and retrospective collection of nonclinical data and resource utilization data. SETTING: Urban, tertiary-care, teaching hospital. PATIENT POPULATION: 992 consecutive patients over the age of 30 years, admitted from the emergency department for evaluation of acute chest pain unexplained by obvious trauma or chest roentgenographic abnormality, were eligible for the study. After excluding patients who had left against medical advice, who had been transferred to another hospital, or who had incomplete utilization data, 903 patients were included in the analyses. MEASUREMENTS AND OUTCOMES: The authors evaluated the effects of 22 clinical and nonclinical factors on resource use. Resource use was primarily evaluated by length of stay; charges were evaluated in secondary analyses. RESULTS: In the entire study population, increased length of stay was associated with a diagnosis of acute myocardial infarction or angina, severity of complications, use of invasive and noninvasive testing, and initial triage to the coronary care unit. In the 424 (47%) patients who had had completely uncomplicated courses after admission, high coefficients of variability were found for length of stay (0.88) and for total charges (0.78). In these uncomplicated patients, increased length of stay was associated with the use of noninvasive cardiac testing (66% longer for patients undergoing echocardiography or radionuclide ventriculography, and 46% longer for patients undergoing exercise tests or ambulatory arrhythmia monitoring), initial triage to the coronary care unit (23% longer), admission at the end of the week (21% longer), and insurance coverage other than Blue Cross/Blue Shield or a commercial carrier (21% for self-pay, 25% for Medicaid, and 48% for Medicare). CONCLUSIONS: These findings indicate that after adjustment for important clinical factors, nonclinical factors had a significant impact on length of stay among a large group of uncomplicated patients. Interventions aimed at reducing logistic difficulties in the performance of noninvasive testing and decreasing the number of low-risk patients who are triaged to coronary care unit beds may decrease resource utilization.

Angina Pectoris↗

PubMed2002

Establishing a health outcomes and economics center in radiology: strategies and resources required.

PURPOSE: To describe the resources and strategies required to establish a health outcomes and economics center in radiology. METHODS: Human and nonhuman resources required to perform sound outcomes and economics studies in radiology are reviewed. RESULTS: Human resources needed include skilled medical and nonmedical staff. Nonhuman resources required are: (1). communication and information network; (2). education tools and training programs; (3). budgetary strategies; and (4). sources of income. Effective utilization of these resources allows the performance of robust operational and clinical research projects in decision analysis, cost-effectiveness, diagnostic performance (sensitivity, specificity, and ROC curves), and clinical analytical and experimental studies. CONCLUSION: As new radiologic technology and techniques are introduced in medicine, society is increasingly demanding sound clinical studies that will determine the impact of radiologic studies on patient outcome. Health-care funding is scarce, and therefore third-party payers and hospitals are demanding more efficiency and productivity from radiologic service providers. To meet these challenges, radiology departments could establish health outcomes and economics centers to study the clinical effectiveness of imaging and its impact on patient outcome.

Budgets↗

PubMed2006

Multi-criteria assessment of tensions in resource use at continental scale: a proof of concept with Australian rangelands.

The purpose of this study was to help to inform policy development for the Australian rangelands, and provide a proof of concept for application of a multi-criteria analysis approach to assessment of competing resource use at continental scale. The study aimed to identify and locate key natural resource and agricultural production assets in the rangelands, define a number of measures of potentially threatening processes, and use a multi-criteria approach to identify areas where threatening processes, agricultural production problems, or valuable natural resources coincided. The analysis used 35 readily available, continental spatial data layers at 5-km pixel resolution ranked from 1 (low) to 5 (high) under three themed groupings: natural resource base, production base, and threatening processes. These measures were aggregated into composite indicators to define attributes such as environmental sensitivity and total grazing pressure. The composites were then compared in a two-way analysis to explore particular interactions between threatening processes such as pastoralism and mining, and the condition of production and natural resource assets. These interactions were defined as "tensions" for purposes of this analysis. Example "tensions" included the association of high grazing intensity with areas of high environmental sensitivity, indicating a risk of land degradation under adverse climatic conditions. A summary of patterns of tension was obtained by extracting area proportions of high-tension classes for selected Natural Heritage Trust Regions, which are a basis for Australian Government funding of improved environmental management. The study provides a basis for further examination of trade-offs in the use of natural assets, opportunities for improved productivity and sustainability, and social and economic implications.

Agriculture↗

PubMed1998

Assessing Land-Use Impacts on Natural Resources

/ Much information is available on changes that occur in natural resources from both spatially-explicit data on environmental conditions and models of the interactions of these conditions and resources with human activities. The strategy for assessing land-use impacts on natural resources developed in this paper provides a framework for using relevant data and models to address questions of how management practices can promote both use and protection of resources. This assessment strategy integrates spatially explicit environmental data using geographic information systems (GIS) with computer models that simulate changes in land cover in response to land-use impacts. The computer models also simulate susceptibility of species to changes in habitat suitability and landscape patterns. The approach is applied to management of limestone barrens on the Oak Ridge Reservation in East Tennessee. Potential limestone barrens habitats are identified by overlaying appropriate soils, geology, slope, and land-use/land-cover conditions. Their validity is tested against known sites containing rare species that occur in these habitats. The location of habitats at risk in the aftermath of human activities is determined by using an available area model that identifies the size and proximity of sites that particular types of species can no longer use as habitat. The resulting risk map can be used in land management planning. The approach uses readily available in situ and remotely sensed data and is applicable to a wide range of locations and land-use scenarios. This approach can be refined based on needs identified by land managers and on the sensitivity of the results to the resolution of available resource information.KEY WORDS: Land management; Assessment; Habitat characterization; Limestone barrens; Ecological modeling; Geographic information systems

Journal Article↗

PubMed1999

RESEARCH: Evaluating Sustainability of Watershed Resources Management Through Wetland Functional Analysis.

/ Unsustainable agricultural policies and water and soil resource schemes have drained two thirds of Mediterranean wetlands since 1920. An outstanding example is Karla in Greece, a former internationally important wetland that was drained in 1962 causing environmental, social, and water and soil problems. The objective of this study was to assess the functions and values of Karla, at three periods of its history, and to relate them to major events in the management of the water and soil resources of its watershed. Information on wetland and watershed features was collectedfrom historical records and field visits. The results showed that the wetland in its pristine state had performed five functions to a high degree, one (groundwater recharge) to a moderate degree, and one (flood storage) to a low degree. Flood-control works, uncontrolled pumping, etc., in 1936-1961 degraded all functions except microclimate modification while, the bird support function was moderately altered. Drainage works in 1962 left a very small artificially flooded wetland with only four functions performed to an insignificant degree. Value degradation followed function degradation. It was concluded that past resource management has been nonintegrated. No consideration was given to the multiple functions and values of Karla. Previous restoration proposals involved the reinstatement of one or two functions only. The appropriate restoration scheme for Karla must be multiobjective and based on the integrated resource management of its own and the neighboring watersheds.KEY WORDS: Soil and water resources; Sustainability; Watershed management; Wetland functional analysis; Karla wetlandhttp://link.springer-ny.com/link/service/journals/00267/bibs/24n2p193.html

Journal Article↗

PubMed2004

Scale-dependent relationships between the spatial distribution of a limiting resource and plant species diversity in an African grassland ecosystem.

One cornerstone of ecological theory is that nutrient availability limits the number of species that can inhabit a community. However, the relationship between the spatial distribution of limiting nutrients and species diversity is not well established because there is no single scale appropriate for measuring variation in resource distribution. Instead, the correct scale for analyzing resource variation depends on the range of species sizes within the community. To quantify the relationship between nutrient distribution and plant species diversity, we measured NO(3)(-) distribution and plant species diversity in 16 paired, modified Whittaker grassland plots in Serengeti National Park, Tanzania. Semivariograms were used to quantify the spatial structure of NO(3)(-) from scales of 0.4-26 m. Plant species diversity (Shannon-Weiner diversity index; H ') was quantified in 1-m(2) plots, while plant species richness was measured at multiple spatial scales between 1 and 1000 m(2). Small-scale variation in NO(3)(-) (<0.4 m) was positively correlated with 1-m(2) H ', while 1000-m(2) species richness was a log-normal function of average NO(3)(-) patch size. Nine of the 16 grassland plots had a fractal (self-similar across scales) NO(3)(-) spatial distribution; of the nine fractal plots, five were adjacent to plots that had a non-fractal distribution of NO(3)(-). This finding offered the unique opportunity to test predictions of Ritchie and Olff (1999): when the spatial distribution of limiting resources is fractal, communities should display a left-skewed log-size distribution and a log-normal relationship between net primary production and species richness. These predictions were supported by comparisons of plant size distributions and biomass-richness relationships in paired plots, one with a fractal and one with a non-fractal distribution of NO(3)(-). In addition, fractal plots had greater large-scale richness than paired non-fractal plots (1,0-1000 m(2)), but neither species diversity ( H') nor richness was significantly different at small scales (1 m(2)). This result is most likely explained by differences in the scale of resource variation among plots: fractal and non-fractal plots had equivalent NO(3)(-) variation at small scales but differed in NO(3)(-) variation at large scales (as measured by the fractal dimension). We propose that small-scale variation in NO(3)(-) is largely due to the direct effects of plants on soil, while patterns of species richness at large scales is controlled by the patch size and fractal dimension of NO(3)(-) in the landscape. This study provides an important empirical step in understanding the relationship between the spatial distribution of resources and patterns of species diversity across multiple spatial scales.

Africa↗

PubMed2004

Hierarchy of responses to resource pulses in arid and semi-arid ecosystems.

In arid/semi-arid ecosystems, biological resources, such as water, soil nutrients, and plant biomass, typically go through periods of high and low abundance. Short periods of high resource abundance are usually triggered by rainfall events, which, despite of the overall scarcity of rain, can saturate the resource demand of some biological processes for a time. This review develops the idea that there exists a hierarchy of soil moisture pulse events with a corresponding hierarchy of ecological responses, such that small pulses only trigger a small number of relatively minor ecological events, and larger pulses trigger a more inclusive set and some larger ecological events. This framework hinges on the observation that many biological state changes, where organisms transition from a state of lower to higher physiological activity, require a minimal triggering event size. Response thresholds are often determined by the ability of organisms to utilize soil moisture pulses of different infiltration depth or duration. For example, brief, shallow pulses can only affect surface dwelling organisms with fast response times and high tolerance for low resource levels, such as some species of the soil micro-fauna and -flora, while it takes more water and deeper infiltration to affect the physiology, growth or reproduction of higher plants. This review first discusses how precipitation, climate and site factors translate into soil moisture pulses of varying magnitude and duration. Next, the idea of the response hierarchy for ecosystem processes is developed, followed by an exploration of the possible evolutionary background for the existence of response thresholds to resource pulses. The review concludes with an outlook on global change: does the hierarchical view of precipitation effects in ecosystems provide new perspectives on the future of arid/semiarid lands?

Adaptation, Physiological↗

PubMed2004

Root foraging for patchy resources in eight herbaceous plant species.

The root foraging strategy of a plant species can be characterized by measuring foraging scale, precision, and rate. Trade-offs among these traits have been predicted to contribute to coexistence of competitors. We tested for trade-offs among root foraging scale (total root mass and length of structural roots), precision (ln-ratio of root lengths in resource-rich and resource-poor patches), and rate (days required for roots to reach a resource-rich patch, or growth rate of roots within a resource-rich patch) in eight co-occurring species. We found that root foraging scale and precision were positively correlated, as were foraging scale and the rate of reaching patches. High relative growth rate of a species did not contribute to greater scale, precision, or rate of root foraging. Introduced species had greater foraging scale, precision, and rate than native species. The positive correlations between foraging scale and foraging precision and rate may give larger species a disproportionate advantage in competition for patchy soil resources, leading to size asymmetric competition below ground.

Adaptation, Physiological↗

PubMed2004

Who is the top dog in ant communities? Resources, parasitoids, and multiple competitive hierarchies.

A wide variety of animal communities are organized into interspecific dominance hierarchies associated with the control and harvest of food resources. Interspecific dominance relationships are commonly found to be linear. However, dominance relations within communities can form a continuum ranging from intransitive networks to transitive, linear dominance hierarchies. How interference competition affects community structure depends on the configuration of the dominance interactions among the species. This study explores how resource size and the trait-mediated indirect effect (TMIE) specialist phorid fly parasitoids exert on interference competition, affect the transitive nature of competitive interactions in an assemblage of woodland ants. I quantify the linearity of networks of interactions associated with large and small food resources in the presence and absence of phorid parasitoids. Two distinct, significantly linear dominance hierarchies exist within the ant assemblage depending on the size of the disputed resource. However, the presence of phorid fly parasitoids eliminates the linearity of both dominance hierarchies. The host's phorid defense behaviors reduce the competitive asymmetries between the host and its subdominant competitors, increasing the indeterminacy in the outcome of competitive interactions. Thus, both resource size variation and phorid-induced TMIEs appear to facilitate coexistence in assemblages of scavenging ants.

Animals↗

PubMed2005

Interactions between a detrital resource pulse and a detritivore community.

Detritivore communities influence the decomposition of detrital resources in virtually all natural systems. Conversely, detrital resources can also have considerable bottom-up effects on detritivore communities. While many investigations have examined detritivory and decomposition processes, few have considered interactions between detritivores and detritus as concurrent processes in the same system, or in the context of natural detrital pulses. In many systems, resource pulses contribute substantial detrital inputs to belowground systems. These detrital pulses may influence interactions between the detritivore community and detrital decomposition. I conducted field experiments to investigate interactions between detrital resource pulses of periodical cicada (Magicicada spp.) carcasses and scavenging detritivorous macroarthropods. Cicada litterfall pulses influenced several broad groups in the macroarthropod community, including relatively specialized necrophilous taxa and relatively generalized detritivores, omnivores and predators. Conversely, detritivore activity increased the rate of cicada carcass decomposition by 4,082% compared to caged control carcasses. These results suggest that interactions between pulses of cicada detritus and the detritivore community influence both the persistence of ephemeral detrital resources, and the distribution, abundance and behavior of detritivore populations.

Animals↗

PubMed2006

Resource translocation within seagrass clones: allometric scaling to plant size and productivity.

The allometric scaling of resource demand and translocation within seagrass clones to plant size (i.e. shoot mass and rhizome diameter), shoot production and leaf turnover was examined in situ in eight seagrass species (Cymodocea nodosa, Cymodocea serrulata, Halophila stipulacea, Halodule uninervis, Posidonia oceanica, Thalassodendron ciliatum, Thalassia hemprichii and Zostera noltii), encompassing most of the size range present in seagrass flora. One fully developed shoot on each experimental rhizome was incubated for 2-3 h with a pulse of NaH(13)CO(3) (235 micromol) and (15)NH(4)Cl (40 micromol). The mobilisation of incorporated tracers across the clone was examined 4 days later. Carbon and nitrogen demand for shoot production across seagrass species scaled at half of the shoot mass, whereas seagrass leaves incorporated tracers ((13)C and (15)N) at rates proportional to the shoot mass. The shoots of all seagrass species shared resources with neighbours, particularly with younger ones. The time scales of physiological integration and the absolute amount of resources shared by seagrass ramets scaled at 2.5 power of the rhizome diameter. Hence, the ramets of larger species were physiologically connected for longer time scales and share larger absolute amounts of resources with neighbours than those of smaller species. The different pattern of resource translocation exhibited by seagrasses helps explain the ecological role displayed by these species and the success of large seagrasses colonising nutrient-poor coastal areas, where they often dominate.

Alismatales↗

PubMed1985

Effectiveness of hardiness, exercise and social support as resources against illness.

The effects of the resistance resources of personality hardiness, exercise, and social support, taken singly and in combination, on concurrent and prospective levels, and probability of illness were studied. In 1980, 85 male business executives identified as high in stressful events were tested for the three resistance resources. Predicting their illness scores in 1980 formed the concurrent aspect of the study. For the prospective aspect, illness scores in 1981 were available on 70 of the subjects. With regard to resistance resources, when there are none, one, two or three, the level and probability of both concurrent and prospective illness drop in a regular and marked fashion. These results highlight the importance of multiple resistance resources. Estimates of relative effectiveness indicate that hardiness is the most important of the resistance resources studied.

Disease↗

PubMed1983

Learning from the Japanese: management in a resource-scarce world.

The principal value of studying the Japanese managerial system, according to Zussman, lies not in the prospect of copying it or of finding secrets for success, but in our ability to identify the relationship between the material resource position of an economy and the managerial systems that will be most effective in it. Zussman briefly discusses the historical development of the Japanese response to their resource-poor homeland and the principles they identified for success through the utilization of human resources--the one resource they had in abundance. He also cites the United States's historical response to its resource position as a source of our present economic difficulties. He contends that the structural changes required to cure our economic woes include eliminating the "entitlement" culture, developing better processes for employee selection, utilizing nonmonetary rewards, and adopting different criteria for selection and promotion of managers.

Economic Competition↗

PubMed2004

Mental effort causes vigilance decrease due to resource depletion.

The resource view on vigilance performance was tested. First, a low demanding task was compared with a similar low demanding task in which stimulus presentation was less monotonous due to added, irrelevant, stimuli. The resource view, maintaining that vigilance is lowered by hard mental work, predicts that addition of irrelevant stimuli will not affect performance. The classic arousal theory, however, states that arousal drops due to monotonous stimulus presentation and predicts that decreasing monotony will enhance performance. Results showed that performance was unaffected by added stimuli. Second, we tested whether a high-demanding task (with identical stimulus presentation as the low demanding task, but different instruction) would cause a greater decline in performance than the low demanding task. Indeed, in the high-demanding task performance was affected most. In sum, it appears that vigilance decreases due to hard mental work, which requires many resources. Both overall performance and decrement in performance can be explained in terms of resources, and this suggests that vigilance tasks should be resource-demanding tasks, which do not have to be of long duration.

Adult↗

PubMed2003

Demand on ED resources during periods of widespread influenza activity.

The purpose of this study was to investigate ED resource demand during periods of Centers for Disease Control and Prevention (CDC)-declared widespread influenza activity (WIA). An observational analysis of secondary data describing ED resource demand was performed using computerized ED patient data over a 130-week period. Measures of ED resource utilization were compared during WIA and non-WIA periods. These measures included weekly census; percentage of patients triaged as having fever, infection, or respiratory (flu index) chief complaints; admission rate, ED LOS (length of stay), total bed time (TBT), the number of patients who left the ED without being seen by a physician (LWBS), and ED saturation time. The study included 34 weeks of CDC-designated WIA occurring over 3 distinct periods. During WIA, the flu index was elevated, 23% (95% confidence interval [CI], 20-25) versus 17% (95% CI, 16-17). There was increased resource utilization during WIA periods compared with the non-WIA periods for the following parameters: admission rate (24% [95% CI, 24-25%] versus 23% [23-23%]), ED LOS admitted (296 [95% CI, 280-313] versus 271 [95% CI, 265-277]), ED LOS discharged (162 [95% CI, 156-168] versus 152 [95% CI, 150-154]), ED saturation time (1292 [95% CI, 689-1894] versus 409 [95% CI, 209-609]) and LWBS (31 [95% CI, 19-42] versus 14 [95% CI, 12-15]). Although each WIA period was marked by an initial spike in patient volume, weekly census did not increase (1365 [95% CI, 1297-1433] during WIA versus 1297 [95% CI, 1275-1320] during non-WIA). An association between WIA and greater ED resource demand was observed. A spike in census was observed at the onset of each WIA period. In addition, the flu index increased during WIA, suggesting the use of the ED as a site for syndromic surveillance of WIA onset.

Centers for Disease Control and Prevention, U.S.↗

PubMed2004

Evaluating daily nursing use and needs in the intensive care unit: a method to assess the rate and appropriateness of ICU resource use.

BACKGROUND: We designed a tool to measure the rate and appropriateness of intensive care unit (ICU) nursing coverage as a proxy for the use of resources. METHODS: We tested the tool in 32 Italian ICUs during a cross-sectional study (4 days/week, October 2001 and April 2002). The level of care was classified as high or low. The appropriate patient-to-nurse ratio for both levels (2/1 and 3/1 in this ICU mix) was defined. The provided and theoretical nurse assistance was computed, the difference between the two quantifying the ICU use of personnel: a positive difference means over-utilization, a negative one under-utilization. We calculated the maximum number of high-level and low-level care days available for ICU and the relative utilization rates. These two rates quantify the appropriateness of resource use in relation to the planned use. RESULTS: Analysing 5783 treatment-days, the tool identified units using almost all available resources (five), overcrowded (14: too small units) or empty (16: too big). Units were overcrowded on account of the high-level of care required (five: utilization rate >100%) or reallocated too much of their residual high-care nursing capacity to low-level care (six). In empty units both utilization rates were lower than expected. CONCLUSIONS: The method quantifies the rate and appropriateness of resource usage and suggests the best management in units with fixed human resources or a fixed number of beds.

Cross-Sectional Studies↗