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One Period (one + period)
Selected AbstractsWhen density dependence is not instantaneous: theoretical developments and management implicationsECOLOGY LETTERS, Issue 2 2008Irja I. Ratikainen Abstract Most organisms live in changing environments or do not use the same resources at different stages of their lives or in different seasons. As a result, density dependence will affect populations differently at different times. Such sequential density dependence generates markedly different population responses compared to the unrealistic assumption that all events occur simultaneously. Various field studies have also shown that the conditions that individuals experience during one period can influence success and per capita vital rates during the following period. These carry-over effects further complicate any general principles and increase the diversity of possible population dynamics. In this review, we describe how studies of sequential density dependence have diverged in directions that are both taxon-specific and have non-overlapping terminology, despite very similar underlying problems. By exploring and highlighting these similarities, we aim to improve communication between fields, clarify common misunderstandings, and provide a framework for improving conservation and management practices, including sustainable harvesting theory. [source] Annual movement of adult pike (Esox lucius L.) in a lowland riverECOLOGY OF FRESHWATER FISH, Issue 2 2006A. Koed Abstract,,, The movement of ten radio-tagged adult pikes (57,113 cm) in the River Gudenå, Denmark, was investigated from September 1998 to September 1999. The movements of pike were characterised by long resident periods in the submergent vegetation, interrupted by short excursions to nearby areas. Two periods with more intense movement were observed; one period during early winter; and one period during spring from mid-March to mid-May. The increased movement during early winter may have been initiated by a slight temperature increase at this time, whereas the increased movement during spring coincided with the spawning of pike. Despite suitable spawning areas nearby the areas where pike resided most of the year, several pike, mainly females, migrated to distant localities during spring. [source] Estimating the Technology of Cognitive and Noncognitive Skill FormationECONOMETRICA, Issue 3 2010Flavio Cunha This paper formulates and estimates multistage production functions for children's cognitive and noncognitive skills. Skills are determined by parental environments and investments at different stages of childhood. We estimate the elasticity of substitution between investments in one period and stocks of skills in that period to assess the benefits of early investment in children compared to later remediation. We establish nonparametric identification of a general class of production technologies based on nonlinear factor models with endogenous inputs. A by-product of our approach is a framework for evaluating childhood and schooling interventions that does not rely on arbitrarily scaled test scores as outputs and recognizes the differential effects of the same bundle of skills in different tasks. Using the estimated technology, we determine optimal targeting of interventions to children with different parental and personal birth endowments. Substitutability decreases in later stages of the life cycle in the production of cognitive skills. It is roughly constant across stages of the life cycle in the production of noncognitive skills. This finding has important implications for the design of policies that target the disadvantaged. For most configurations of disadvantage it is optimal to invest relatively more in the early stages of childhood than in later stages. [source] On the compensation of non-active current components of three-phase loads with quickly changing unsymmetryEUROPEAN TRANSACTIONS ON ELECTRICAL POWER, Issue 5 2001V. Staudt Some types of loads, like arc furnaces, present a special challenge to compensation strategies. They vary quickly and have a very high rated power. For example the arcs of an arc furnace are not burning continuously especially when starting the melting process. This causes variations of the line voltage with frequencies well below the line frequency commonly known as voltage flicker. Because of cost efficiency the energy storage capability of compensators for the mitigation of voltage flicker effects can still only be small compared to the energy taken by the arc furnace during one period of the line voltage. This paper discusses the use of a compensation tool which quickly detects negative sequence current components in comparison to the calculation of an equivalent conductance using the so-called FBD method (Fryze-Buchholz-Depenbrock method). Simulations are used to demonstrate the advantages and disadvantages of the tool for detecting negative sequence current components. It is shown that the quick detection and compensation of negative sequence current components can reduce the amount of voltage flicker considerably. [source] Automated generation of new knowledge to support managerial decision-making: case study in forecasting a stock marketEXPERT SYSTEMS, Issue 4 2004Se-Hak Chun Abstract: The deluge of data available to managers underscores the need to develop intelligent systems to generate new knowledge. Such tools are available in the form of learning systems from artificial intelligence. This paper explores how the novel tools can support decision-making in the ubiquitous managerial task of forecasting. For concreteness, the methodology is examined in the context of predicting a financial index whose chaotic properties render the time series difficult to predict. The study investigates the circumstances under which enough new knowledge is extracted from temporal data to overturn the efficient markets hypothesis. The efficient markets hypothesis precludes the possibility of anticipating in financial markets. More precisely, the markets are deemed to be so efficient that the best forecast of a price level for the subsequent period is precisely the current price. Certain anomalies to the efficient market premise have been observed, such as calendar effects. Even so, forecasting techniques have been largely unable to outperform the random walk model which corresponds to the behavior of prices under the efficient markets hypothesis. This paper tests the validity of the efficient markets hypothesis by developing knowledge-based tools to forecast a market index. The predictions are examined across several horizons: single-period forecasts as well as multiple periods. For multiperiod forecasts, the predictive methodology takes two forms: a single jump from the current period to the end of the forecast horizon, and a multistage web of forecasts which progresses systematically from one period to the next. These models are first evaluated using neural networks and case-based reasoning, and are then compared against a random walk model. The computational models are examined in the context of forecasting a composite for the Korean stock market. [source] Return migration of adult Atlantic salmon, Salmo salar, in relation to water diverted through a power stationFISHERIES MANAGEMENT & ECOLOGY, Issue 1 2003E. B. Thorstad Abstract ,The migration of Atlantic salmon, Salmo salar L., returning to the River Suldalslågen, Norway, was studied in relation to redirection of freshwater flow through a power station. The outlet of the power station is situated in the Hylsfjord, a fjord adjacent to the river mouth. Seventy-two salmon were tagged with acoustic transmitters, released in the outer part of the fjord system and automatically recorded when entering the Hylsfjord or the river. Data were collected during one period when the power station was running and two periods when the power station was closed. The release of water from the power station did not greatly attract the salmon during their return migration. Proportions of salmon entering the river or time from release to entering the river did not differ among salmon tagged in the different periods. The salmon were recorded in the Hylsfjord both when the power station was running and closed and there were no differences in number of times, number of days or hours recorded in the Hylsfjord among salmon tagged in the three periods. The only significant difference found among periods was duration of continuous stays in the inner part of the Hylsfjord. This may indicate a slight attraction to the freshwater release, but the difference seems small (1.8 vs. 0.7 h) compared with the time the fish stayed in the fjord system before entering the river (16,85 days). [source] Complexity as a constraint on firm expansion within and across industriesMANAGERIAL AND DECISION ECONOMICS, Issue 6 2009Thomas Hutzschenreuter With this paper, we want to shed light on factors influencing a firm's rate of expansion. We argue that expansion is a complex task and complexity associated with expansion projects in one period can negatively impact rate of expansion in the following period. Moreover, we argue that firm portfolio complexity also slows down further expansion. Using longitudinal data on the expansion path of 91 German companies, we show that added product scope of expansion and degree of internationalization characterizing expansion in one period as well as level of product and international diversity have a significant impact on slowing down rate of expansion in the subsequent period. Copyright © 2008 John Wiley & Sons, Ltd. [source] Modelling suppressed and active convection.THE QUARTERLY JOURNAL OF THE ROYAL METEOROLOGICAL SOCIETY, Issue 626 2007Comparing a numerical weather prediction, cloud-resolving, single-column model Abstract This paper describes the design of and basic results from a case study to compare simulations of convection over the Tropical West Pacific. Simulations are carried out using a cloud-resolving model (CRM), a global numerical weather prediction (NWP) model and a single-column version of the NWP model (SCM). The experimental design for each model type is discussed and then results are compared. The periods simulated each include a regime with strong convective activity, a much more suppressed regime with far less convection, as well as the transition between these regimes. The description of the design and basic results from this study are given in some detail, as a study including all these model types is relatively new. Comparing the local forcing due to the dynamics in the NWP model with the observed forcing used to drive the CRM and SCM it is found that there is good agreement for one period chosen but significant differences for another. This is also seen in fields such as rain rate and top-of-atmosphere radiation. Using the period with good agreement we are able to identify examples of biases in the NWP model that are also reproduced in the SCM. Also discussed are examples of biases in the NWP simulation that are not reproduced in the SCM. It is suggested that understanding which biases in the SCM are consistent with the full NWP model can help focus the use of an SCM in this framework. © Crown Copyright 2007. Reproduced with the permission of the Controller of HMSO. Published by John Wiley & Sons, Ltd [source] Paintings, Films and Fast Cars: A Case Study of Hubert von HerkomerART HISTORY, Issue 2 2002Lynda Nead In a recent conversation with Bruno Latour, the French philosopher Michel Serres visualized his concept of modernity through the image of the automobile. The car, Serres argued, could not be defined as uniquely of one period or as belonging exclusively to the modern, being ,a disparate aggregate of scientific and technical solutions dating from different periods , The ensemble is only contemporary by assemblage.' This metaphor offers a highly productive way of looking at the history and forms of visual culture in Britain in the early twentieth century, when the technological and commercial possibilities of nineteenth-century optical developments were filtering into all aspects of cultural production and consumption. The article examines this moment via a case study of the artist Hubert von Herkomer; offering a reassessment through an examination of his paintings, films and fast cars and thereby proposing a reframing of the history of British visual culture through the integration of still and moving images. [source] Cancer incidence and mortality in a New Zealand community potentially exposed to 2, 3, 7, 8-tetrachlorodibenzo- p -dioxin from 2, 4, 5-trichlorophenoxyacetic acid manufactureAUSTRALIAN AND NEW ZEALAND JOURNAL OF PUBLIC HEALTH, Issue 1 2007Deborah Read Objective: To investigate whether the rates of all cancers and four cancers (soft tissue sarcoma, non-Hodgkin's lymphoma, Hodgkin's disease and chronic lymphocytic leukaemia) associated with dioxin exposure are higher in New Plymouth, the site of a former 2, 4, 5-T manufacturing plant, than for the rest of New Zealand. Methods: Analysis of 1970,2001 cancer data from the New Zealand Cancer Registry was undertaken for New Plymouth and the rest of New Zealand. Results: There is no evidence of an increased cancer risk apart from one period (1970-74), which falls partly outside the 1962,1987 manufacturing period if 10-year latency is assumed. For 1970-74, there was an elevated risk for all cancer incidence (SIR=111, 95% CI 104,119), and for two of the four specific cancers that are associated with dioxin exposure (non-Hodgkin's lymphoma SIR=175, 95% CI 121,246 and chronic lymphocytic leukaemia SIR=251, 95% CI 144,408). Conclusions and Implications: The results do not suggest an increased cancer risk among the New Plymouth population related to the period of 2, 4, 5-T manufacture, although the study's limitations mean the possibility of an undetectable small elevation in cancer risk cannot be excluded. Although TCDD exposure in the first few years of 2, 4, 5-T manufacture may have contributed to cancer incidence in 1970-74, unknown exposure(s) before the start of 2, 4, 5-T manufacture and chance are also possible explanations. [source] CHARTING THE "TRANSITIONAL PERIOD": THE EMERGENCE OF MODERN TIME IN THE NINETEENTH CENTURYHISTORY AND THEORY, Issue 1 2006GÖRAN BLIX ABSTRACT This paper seeks to chart a concept of historical experience that French Romantic writers first developed to describe their own relationship to historical time: the notion of the "transitional period." At first, the term related strictly to the evolving periodic conception of history, one that required breaks, spaces, or zones of indeterminacy to bracket off periods imagined as organic wholes. These transitions, necessary devices in the new grammar of history, also began to attract interest on their own, conceived either as chaotic but creative times of transformation, or, more often, as slack periods of decadence that possessed no proper style but exhibited hybrid traits. Their real interest, however, lies in their reflexive application to the nineteenth century itself, by writers and historians such as Alfred de Musset, Chateaubriand, Michelet, and Renan, who in their effort to define their own period envisioned the "transitional period" as a passage between more coherent and stable historical formations. This prospective self-definition of the "age of history" from a future standpoint is very revealing; it shows not just the tension between its organic way of apprehending the past and its own self-perception, but it also opens a window on a new and paradoxical experience of time, one in which change is ceaseless and an end in itself. The paper also presents a critique of the way the term "modernity" has functioned, from Baudelaire's initial use to the present, to occlude the experience of transition that the Romantics highlighted. By imposing on the nineteenth-century sense of the transitory a heroic period designation, the term "modernity" denies precisely the reality it describes, and sublimates a widespread temporal malaise into its contrary. The paper concludes that the peculiarly "modern" mania for naming one's period is a function of transitional time, and that the concept coined by the Romantics still governs our contemporary experience. [source] | ||||||||||||||||||||||