Dew-worms in white nights: High-latitude light constrains earthworm (Lumbricus terrestris) behaviour at the soil surface

Soil is an effective barrier to light penetration that limits the direct influence of light on belowground organisms. Variation in aboveground light conditions, however, is important to soil-dwelling animals that are periodically active on the soil surface. A prime example is the earthworm Lumbricus terrestris L. (the dew-worm), an ecosystem engineer that emerges nocturnally on the soil surface. In the summer, the northernmost populations of L. terrestris are exposed to a time interval with no daily dark period. During a two-week period preceding the summer solstice, we studied the constraints that boreal night illumination imposes on L. terrestris surface activity by comparing their behaviour under ambient light with artificially-induced darkness. Looking for evidence of geographical divergence in light response, we compared the behaviour of native L. terrestris (Jokioinen, S–W Finland; 60°48′N) with two markedly more southern populations, from Preston (Lancashire, UK; 53°47′N) and Coshocton (Ohio, USA; 40°22′N) where the nights have a period of darkness throughout the year (total latitudinal range ca. 2300 km). Under ambient light conditions, L. terrestris emergence on the soil surface was diminished by half compared with the darkened treatment and it peaked at the darkest period of the night. Also mating rate decreased considerably under ambient light. The native dew-worms were generally the most active under ambient light. They emerged earlier in the evening and ceased their activity later in the morning than dew-worms from the two more southerly populations. The differences in behaviour were, however, significant mainly between native and UK dew-worms. In the darkened treatment, the behaviour of the three earthworm origins did not differ. Under the experimental conditions light condition was the dominant environmental factor controlling surface activity, but elevated night-time air temperature and humidity also encouraged dew-worm emergence without discernible differences among geographical origins. Our results show, that in boreal summer, the high level of night illumination strongly limits soil-surface activity of dew-worms. Considering the important regulatory role of L. terrestris in many ecosystem processes, this can have significant corollaries in dew-worm impacts on the environment. Although evidence for geographical differentiation in behaviour was obtained, the results point to phenotypic flexibility in L. terrestris light response

A new method to identify the optimal temperature of latent-heat thermal-energy storage systems for power generation from waste heat

The integration of thermal-energy storage (TES) within waste-heat recovery power generation systems has the potential to improve energy-efficiency in many industrial processes with variable and/or intermittent waste-heat streams. The first objective of this paper is to present a novel model of these systems that can be used at an early design stage to provide fast and accurate estimates of performance. More specifically, the method can identify the optimal temperature of latent-heat TES systems for waste-heat recovery applications based only on the known heat-source and heat-sink conditions (i.e., temperature, mass-flow rate and specificheat capacity), and can assess both single-stage and cascaded systems. The model has been validated against optimal organic Rankine cycle systems identified from a thermodynamic cycle optimisation. The second objective is to identify the characteristics of optimal systems for different heat-source profiles. The results indicate that, for a given application, there exists an optimal temperature for the latent-heat TES system that depends primarily on the relative size of the heat sink. Moreover, it is found that, for a heat engine operating with TES, the power rating ranges between 25% and 60% of the corresponding power rating for an optimal heat engine, operating without TES, that adapts instantaneously to heat-source fluctuations, whilst the total energy production is reduced by between 45% and 85% respectively. Finally, a small deviation is observed between the results obtained for the different heat sources considered, which suggests that these findings can be extrapolated to other heat sources not considered within this study

Effective Job Search Practice in the UK's Mandatory Welfare-to-Work Programme for Youth

Administrative data from the UK’s main welfare-to-work programme for unemployed and disadvantaged youth is analysed to identify differences in practice between local delivery areas, and to assess their effects on off-welfare outcomes. The findings reveal important similarities in the nature of effective ‘work first’ practices between this programme and some US programmes, despite large differences in the welfare context and systems.

Puerto Ricans: White or Non- White?

The question of race and racial identity among Puerto Ricans has been one of great confusion and misunderstanding. The confusion and misunderstanding exist both among Puerto Ricans and Anglo-Americans. This is a study of the paradox of race perceptions among mainland-bred and island-bred Puerto Ricans. This study was undertaken to look at several related issues: What are the racial perceptions and attitudes held by Puerto Ricans, both on the island and the continental mainland? Further, to what extent has Americanization of Puerto Ricans affected those perceptions and attitudes? Likewise, what role does class consciousness and class mobility play? How do Anglo-American racial perceptions and attitudes affect the Puerto Rican\u27s image of self? And finally, do individual variables such as one\u27s skin color, ethnic identity or pride, personal prejudices or family background further affect these perceptions and attitudes

The Secretary Problem with a Call Option

In addition to accepting or rejecting a candidate arrive at time r, we may consider purchasing an option at a cost cx to recall the candidate at time r+x, but this privilege may be invoked only once. For large sample size, using the best-choice criterion and deducting option costs, the optimal strategy and return are obtained

Selection-Bias Correction in an Evaluation of the Vocational Rehabilitation Program

The article applies a fixed-effect methodology to evaluate the training impacts of the Vocational Rehabilitation program. Two central issues are identification of an acceptable comparison group and adjusting for sources of selection-bias. The use of program dropouts as a comparison group is examined with a modified Hausman test. The results suggest spending on VR may be ore cost-effective in view of the high public cost of serving the disabled in a full dependency mode. These estimates of VR training impacts are compared with the performance of CETA, a public program serving the non-disabled which has been examined extensively using the fixed-effect estimator

Evaluating Educational Inputs in Undergraduate Education

This paper examines the input-output relationship for private undergraduate education. The motivation for such a study stems from a long-standing concern within academe for a better understanding of the relationships between student quality, faculty effort, campus environment, and the end result of an “educated” person. Though precise and objective measures of education output are difficult to formulate, we would argue that alumni achievement is an important and measurable output. Specifically we focus on the number of baccalaureate alumni who went on to earn a Ph.D. But even with an acceptable output measure, research assessments of the educational process are not dealing with a production function in the classical supply-and-demand sense. For example, the purchaser of the product-the student-is also among the more important factor inputs. The implication is that the educational process is far more complicated than a simple, production-function rendering indicates. Consequently, this study formulates a three-equation simultaneous model of student quality, faculty quality, and output. The study’s objective is to identify the relative contribution of the many human and nonhuman resources commonly regarded as producing quality undergraduate education

Optimal Selection with Holding

The arrival times of what we shall call offers constitute a Poisson process. The value of any offer is a nonnegative random variable with known distribution. At an arrival epoch, we may select, reject, or hold the offer. Rejected offers may not be recalled, but an offer on hold is available for future consideration. However, cost accrues during the holding period. We seek a holding and selection strategy that maximizes the expected value of the offer selected less holding costs. The discrete time version of the problem is also considered

Consumer Information Sources: The Provider Perspective

The Federal Office of Consumers\u27 Education (OCE) released, in 1982, an updated definition of consumer education which states that consumer education develops skills, knowledge, and understandings that will help consumers make better purchase decisions. Who is today\u27s consumer? The consumer is a part-time amateur buyer facing, in the marketplace, a whole series of full-time professional sellers. This definition describes the consumer\u27s situation in today\u27s dynamic and complex market. Since the early 1970\u27s, a growing awareness of consumer rights and needs has occurred in the marketplace. This awareness involves the resources necessary for the consumer to cope within the environment