HYDROLOGIC MODELING USING A SIMULATION LANGUAGE BASED ON QUEUEING THEORY1

ABSTRACT: A novel approach has been developed by applying queueing theory to hydrologic modeling. A queueing situation is characterized by a flow of customers arriving randomly at one or more service facilities. In this case, the customers are represented by water and the service time is the time it takes to move through the soil and over the land. This approach has the potential to be simpler and more efficient than some previously developed models. Another important attribute of queueing theory is its ability to model almost unlimited detail. Many simulation languages based on queueing theory have been developed and tested and are available. Applications of the languages include manufacturing operations, transportation systems, computer systems, financial planning, and health care systems. A model was developed, using a simulation language, to predict runoff hydrographs from storms occurring on small homogeneous watersheds. With continued development, queueing theory could provide an effident, detailed approach to simulating many natural processes.     

Bone structure of some marine vertebrates

Bone tissue and bone organ densities, and major components of bone (i.e., ash, organic+CO₂, water and fat) of sperm whale, fin whale, sea lion, albacore, mackerel, rattail and guitarfish were measured. Mammalian vertebrae have higher tissue densities and lower organ densities than fishes. This is because of the high ash and organic content of the bone tissue and the large interstitial volume of the bone organ of mammals. Only albacore and mackerel vertebrae, which had the highest organ densities, and fin whale rib, which had the lowest organ density, contained appreciable quantities of fats. Hydrated tissue densities of all the vertebrates studies are directly correlated with ash content and inversely correlated with water content. Bone structure as related to buoyancy and locomotion is also discussed.     

The evolution of marmot sociality: I. Why disperse late?

Summary Prolonged toleration of offspring in marmots was hypothesized to be (1) a means of preventing dispersal of undersized young (Barash 1974 a) or more generally (2) continued parental investment, increasing the probability of descendant survival and reproduction (Armitage 1981, 1987). These hypotheses are tested in this paper for one of the most social of marmot species, the alpine marmot. The animals studied lived in groups within territories defended by a dominant male and female, or as floaters lacking a well-defined home range. Offspring did not disperse before sexual maturity at age 2 (Fig. 1). Only territorial females bred, whereas territorial males were not able to monopolize reproduction likewise (Table 2). Dispersers had similar spring mass to nondispersers (Table 4). Hence, hypothesis 1 is not supported, at least not for adult-sized, > 2 years old animals. During their residency, 19% of subordinates obtained their natal territory or a neighboring one (Fig. 2). Long distance dispersal bore a high mortality risk. Thus, toleration of mature offspring could well represent parental investment. Other results, however, suggest additional influences on the timing of dispersal. (i) Males dispersed later than females (Fig. 3), possibly because of mate sharing by territorial males (see Emlen 1982). (ii) The higher mass loss of dispersers during the previous winter indicates that weak animals were forced to leave (Table 5) despite presumably lower chances of becoming territorial (Table 3). (iii) Subordinate animals which could not be the offspring of both territorials present were not more likely to disperse (Fig. 3). (iv) Lower dispersal rates when immatures lived in the group (Fig. 3) may indicate benefits from the subordinates' presence for rearing young.     

Shadow cinematography of fish larvae

A simple system of shadow cinematography, consisting of a small tungsten halogen lamp, 2 large biconvex lenses and a 16 mm camera, is described for recording the swimming and feeding behaviour of larval fish. The system can be used either with infra-red film to record swimming behaviour independently of ambient light intensity, or with high-resolution film to record food organisms and feeding behaviour. Small plankton organisms of 0.2 mm width can be resolved using high-resolution film. The technique has been used to record the behaviour of plaice larvae (Pleuronectes platessa L.) feeding on the nauplii of Artemia salina L. The perceptive field of the larvae extends to approximately ±60° in azimuth, ±40° in elevation and 1.5 body lengths in range.     

Effect of El Nĩno on demographic,morphological, and chemical parameters in turtle-grass (Thalassia testudinum): an unexpected test of indicators

We examined the response of demographic, morphological, and chemical parameters of turtle grass (Thalassia testudinum), to much-higher-than-normal rainfall associated with an El Niño event in the winter of 1997–1998. Up to 20 inches of added rain fell between December 1997 and March 1998, triggering widespread and persistent phytoplankton blooms along the west coast of Florida. Water-column chlorophyll concentrations estimated from serial SeaWiFS imagery were much higher during the El Niño event than in the previous or following years, although the timing and magnitude of phytoplankton blooms varied among sites. Seagrass samples collected in 1997, 1998, and 1999 provided an excellent opportunity to test the responsiveness of Thalassia to decline and subsequent improvement of water quality and clarity in four estuaries. Using a scoring technique based on temporal responsiveness, spatial consistency, and statistical strength of indicators, we found that several morphological parameters (Thalassia shoot density, blade width, blade number, and shoot-specific leaf area) were responsive and consistent measures of light stress. Some morphological parameters, such as rhizome apex density, responded to declines and subsequent improvement in water clarity, but lacked the statistical discriminating power necessary to be useful indicators. However, rhizome sugar, starch, and the total carbohydrate concentrations also exhibited spatially and temporally consistent variation as well as statistical strength. Because changes in shoot density, as well as water clarity, affect rhizome carbohydrate levels, a composite metric based on Thalassia shoot density and rhizome carbohydrate levels together is probably more useful than either parameter alone as an indicator of seagrass health.     

Who takes the lead? A multi‐source diary study on leadership,work engagement,and job performance

Transformational leadership is associated with a range of positive outcomes. Yet, according to substitutes for leadership theory, there may be circumstances under which it is difficult, if not impossible, for leaders to inspire and challenge their employees. Therefore, we hypothesize that transformational leadership behaviors as well as employee self‐leadership strategies contribute to employee work engagement and job performance. Furthermore, we hypothesize that transformational leadership behaviors are more effective when employees have a high need for leadership, whereas self‐leadership strategies are more effective when employees have a low need for leadership. A sample of 57 unique leader–employee dyads filled out a quantitative diary survey at the end of each week, for a period of five weeks. The results of multilevel structural equation modeling showed that employees were more engaged in their work and received higher performance ratings from their leader when leaders used more transformational leadership behaviors, and when employees used more self‐leadership strategies. Furthermore, we showed that transformational leadership behaviors were more effective when employees had a high (vs. low) need for leadership and that the opposite was true for employee self‐leadership. These findings contribute to our understanding of the role of employees in the transformational leadership process. Copyright © 2015 John Wiley & Sons, Ltd.     

DEEP RESERVOIR THERMAL STRATIFICATION MODEL1

ABSTRACT. A method of predicting reservoir temperature profiles is presented. The model requires monthly averaged meteorological and hydrological data along with reservoir physical characteristics. The one-dimensional profiles are predicted by solving the time-dependent energy equation with an assumed epilimnetic depth and a diffusion coefficient applicable below the epilimnion. The model is verified using an existing reservoir.     

Regional news portrayals of global warming and climate change

In this study we utilize content analysis techniques to examine how the issue of global warming and climate change has been characterized during the period of 1992 through 2005 by the Houston Chronicle—the largest regional newspaper in the Texas coastal region. A total of 795 global warming and climate change news articles from the Houston Chronicle are collected, coded and analyzed. Data analyses are organized and presented with regard to issue salience, various issue attributes (issue image, scope, linkage, participant, proposed solution and responsible party), use of science, and scientific information sources cited in the news stories. We find that regional media attention to the global climate change issue generally increases over time and an overwhelming majority of the news articles view the issue as a harmful problem. However, given the scientific consensus that global warming will result in significant devastating climate change consequences to the coastal regions, there are still a fair number of news articles delivering mixed, undetermined or even non-harmful messages. We also find that climate change is often discussed as a national or international-global issue, and frequently linked to a number of other public issues rather than just being viewed as an environmental–ecological problem. Moreover, we find that emphasis on issue solutions is placed more on mitigation strategies than on adaptation behaviors, and that both governmental and non-governmental actions and responsibilities are suggested for dealing with climate change. In addition, our findings indicate that the regional newspaper in Texas obtains scientific information on climate change primarily from academic institutions. Implications of our findings and recommendations for future research are discussed in the concluding section.