Testing Theories of Job Creation: Does Supply Create Its Own Demand?

Although search-matching theory has come to dominate labor economics in recent years, few attempts have been made to compare the empirical relevance of search-matching theory to efficiency wage and bargaining theories, where employment is determined by labor demand. In this paper we formulate an empirical equation for net job creation, which encompasses search-matching theory and a standard labor demand model. Estimation on firm-level data yields support for the labor demand model, wages and product demand affect job creation, but we find no evidence that unemployed workers contribute to job creation, as predicted by search-matching theory.job creation, involuntary unemployment, search-matching, labor demand, competitiveness

Control of Heating Chamber on Packaging Machine A1 TFA

On the packaging machine Tetra Pak A1 a heating box is used to sterilize the packaging material. This is done by passing the material through a bath of hydrogen peroxide and then vaporizing the liquid in the heating box. The heating is done by three resistive elements that pass their energy by convection and radiation to the packaging material. Problems occur due to temperature variations on the web of the packaging material. During normal production the temperature variations are small and acceptable. At starts and stops, overshoots cause material damages and undershoot results in peroxide residues forcing disposal of packages. This master's thesis proposes how to optimize the control of the temperature. The control will be divided into three stages; start, running and stop. Different conditions during these stages will force the control logic into three different implementations

Product market imperfections and employment dynamics

How important is imperfect competition in the product market for employment dynamics? To investigate this, we formulate a theoretical model of employment adjustment with imperfect competition in the product market, search frictions, and convex adjustment costs. From this model, we derive a structural equation for employment that we estimate on firm-level data. We find that product market demand shocks have significant and quantitatively large effects on employment. Thus, product market imperfections seem to be important for employment dynamics. However, we find no evidence that the tightness of the local labor market affects job creation in existing firms

Invading herbivory: The golden apple snail alters ecosystem functioning in Asian wetlands

We investigated the effects of an exotic snail, the golden apple snail (Pomacea canaliculata) on biodiversity and ecosystem functioning in tropical wetland ecosystems. This large snail (up to 80-mm shell height) has invaded large parts of Southeast Asia during recent decades. A survey of natural wetlands in Thailand showed that high densities of the snail were associated with almost complete absence of aquatic plants, high nutrient concentrations, and high phytoplankton biomass, that is, a complete shift in both ecosystem state and function. A field experiment demonstrated that grazing by the snail can cause the loss of aquatic plants, a change toward dominance of planktonic algae, and thereby a shift toward turbid water. Estimates of biologically fixed nutrients released through snails grazing on aquatic plants revealed that phosphorus releases were sufficient to explain the recorded increase in phytoplankton biomass. Hence, our study demonstrates how an herbivore may trigger a shift from clear water and macrophyte dominance to a turbid state dominated by planktonic algae. This shift and the continuing aggressive invasion of this exotic species are detrimental to the integrity and functioning of wetland ecosystems, and to the services these provide in Southeast Asia

Production of protein extracts from Swedish red, green, and brown seaweeds, Porphyra umbilicalis Kützing, Ulva lactuca Linnaeus, and Saccharina latissima (Linnaeus) J. V. Lamouroux using three different methods

peer-reviewedThe demand for vegetable proteins increases globally and seaweeds are considered novel and promising protein sources. However, the tough polysaccharide-rich cell walls and the abundance of polyphenols reduce the extractability and digestibility of seaweed proteins. Therefore, food grade, scalable, and environmentally friendly protein extraction techniques are required. To date, little work has been carried out on developing such methods taking into consideration the structural differences between seaweed species. In this work, three different protein extraction methods were applied to three Swedish seaweeds (Porphyra umbilicalis, Ulva lactuca, and Saccharina latissima). These methods included (I) a traditional method using sonication in water and subsequent ammonium sulfate-induced protein precipitation, (II) the pH-shift protein extraction method using alkaline protein solubilization followed by isoelectric precipitation, and (III) the accelerated solvent extraction (ASE®) method where proteins are extracted after pre-removal of lipids and phlorotannins. The highest protein yields were achieved using the pH-shift method applied to P. umbilicalis (22.6 ± 7.3%) and S. latissima (25.1 ± 0.9%). The traditional method resulted in the greatest protein yield when applied to U. lactuca (19.6 ± 0.8%). However, the protein concentration in the produced extracts was highest for all three species using the pH-shift method (71.0 ± 3.7%, 51.2 ± 2.1%, and 40.7 ± 0.5% for P. umbilicalis, U. lactuca, and S. latissima, respectively). In addition, the pH-shift method was found to concentrate the fatty acids in U. lactuca and S. latissima by 2.2 and 1.6 times, respectively. The pH-shift method can therefore be considered a promising strategy for producing seaweed protein ingredients for use in food and feed

Timing-Robust Control over the Cloud Using On-Line Parametric Optimization

In this paper, we present a heuristic method for adapting a networked linear feedback controller to improve its robustness to timing complications, such as long delays, aborted computations, and dropped packets. The core concept of the approach is to log successful sampling and actuation events and then, at discrete time-points, use non-convex parametric optimization to improve the expected performance of the controller under the assumption that the future timing behavior will be similar to the current one. To reduce the time complexity of the optimization algorithm, automatic differentiation is integrated for efficient gradient descent. The approach is evaluated on a physical ball and beam plant, where both the controller and optimization algorithm can be located in the Cloud

Lethal and non-lethal effects of multiple indigenous predators on the invasive golden apple snail (Pomacea canaliculata)

1. We investigated the individual and combined effects of two predators (the climbing perch, Anabas testudineus, and the wetland crab, Esanthelphusa nimoafi) indigenous to wetlands in Laos, on the behaviour and survival of the invasive South American golden apple snail (Pomacea canaliculata). The snail is considered a pest, consuming large amounts of rice and other aquatic vegetation in the region. 2. Snail avoidance reactions to released predator chemical cues were investigated in aquaria while the effects of predators on a mixed snail population were studied in field enclosures that contained native aquatic plants (Salvinia cucullata, Ludwigia adscendens and Ipomoea aquatica). 3. In the aquaria experiment, neonate (2-3 mm) and medium-sized snails (8-10 mm) responded to fish chemical cues by going to the surface, whereas adult snails (35-40 mm) went to the bottom. In contrast, no size class of snails reacted to chemical cues released by crabs. 4. In the field experiment, fish reduced the abundance of neonate snails, and crabs reduced the abundance of all size classes. The effect of the combined predators could not be predicted from the mortality rate observed in single predator treatments. The survival of neonate and medium-sized snails was greater and of adults less than expected. The presence of predators did not affect egg production. Snails consumed significant amounts of plants despite the presence of predators. 5. Our findings suggest that some indigenous Asian predators have lethal and sublethal effects on P. canaliculata that depend on snail size and predator type. When in the presence of several predators the response of snails to one predator may either increase or decrease the vulnerability of snails to the others

Different economic factors importance in an investment of solar panels for poultry farms

Med en ostabil och fluktuerande energimarknad som i sin tur generar en osäker elprismarknad med extrema prisökningar över hela landet gör att ett ökat intresse finns för att investera i solcellsanläggningar i Sverige, speciellt för företag med stort behov av el. Fjäderfäproducenter är en av de branscher som fått se stora elkostnadsökningar då de ofta har ett stort behov av el. Det finns en rad olika solcellsleverantörer att välja på som använder liknande standardiserade dataprogram för att beräkna potentiell produktion och lönsamhet som presenteras i en offert för att göra investeringen mer lukrativ. Offertförslagen som presenteras är inte gjorda för gårdarnas förutsättningar eller tar hänsyn till alla ekonomiska faktorer som påverkar fjäderfäproducenters lönsamhet vid en sådan investering. Studiens syfte är att identifiera och sammanställa olika ekonomiska faktorer som har en påverkan på investering i en solcellsanläggning kopplat till en fjäderfäproduktion och visa på dess olika betydelser. Studien ska ge ett bättre underlag för fjäderfäproducenter vid eventuellt beslut för investering jämfört med offertkalkyler från solcellsföretag. Metoden är en litteraturstudie som baserats på fakta som är inhämtat från fallföretag, vetenskapliga artiklar, sakkunniga rådgivare och webbaserade källor. Källorna har använts till att göra LCOE-analys, investeringskalkyl och känslighetsanalys för en 70KW solcellsanläggning med en 100A säkring med spotpriser från framtidsprognos. LCOE-analys är en modell för att beräkna fram produktionskostnad för investeringen under dess livstid. Studiens resultat visar att storleken på den andel egenanvänd el har en betydande inverkan på investeringens lönsamhet. LCOE-Analysen ger störst indikation på värdet av den egenanvända producerade elen, efter att de ekonomiska faktorerna inkluderats. Som ett exempel är från fallgård 1 ökar break-even spotpriset på investeringen från 0,338kr/kWh till 0,664kr/kWh om egenanvända elen minskar från 75% till 25%. Alla scenarion med olika spotpris och andel egenanvänd el visar på en förlängd återbetalningstid jämfört med offertkalkyl. I det basprisscenariot med den högst troliga framtidsprognosen med 0.65kr/kWh visar kalkylen på en återbetalningstid mellan 13,5-15år med en hög grad egenanvändning för båda fallgårdar. Det är jämförbart med offertkalkylen som visar en återbetalningstid på 6.28 år som är mycket kortare än basprisscenariot. Graferna i resultatet visar hur liten sannolikhet det är för investeringen att matcha återbetalningstiden från solcellsleverantörernas offertkalkylen, även med en hög andel egenanvänd el då de graferna visar på en återbetalningstid på 7 år. Slutsatsen för denna studie är att de identifierade ekonomiska faktorer har en betydande påverkan på anläggningens lönsamhet för fjäderfäproducenter och skiljer sig stort mot offertkalkylerna sett till gårdarnas förutsättningar.With an unstable and fluctuating energy market, which in turn generates an uncertain price market with extreme price increases across the country. There is an increased interest in investing in solar energy installations in Sweden, especially for companies with a large need for electricity. Poultry producers are one of the industries that have seen large increases in electricity costs as they often have a large need for electricity. There are a range of solar suppliers to choose from that use similar standardized computer programs to calculate potential output and profitability which is presented in a quote to make the investment more lucrative. The tender proposals presented are not made for the conditions of the farms or consider all economic factors that affect the profitability of poultry producers in such an investment. The purpose of the study is to identify and compile various economic factors that have an impact on investment in solar energy linked to a poultry production and show its various meanings. The study should provide a better basis for poultry producers in case of a possible investment decision compared to quotation calculations from solar cell companies. The method is a literature study based on facts obtained from case companies, scientific articles, expert advisors, and web-based sources. Those sources have been used to do LCOE analysis, investment calculation and sensitivity analysis for a 70KW solar plant with a 100A fuse with spot prices from future forecast. LCOE analysis is a model for calculate the production cost of the investment. The results of the study show that the size of the proportion of self-used electricity has a significant impact on the profitability of the investment. The LCOE analysis gives the greatest indication of the value of the self-produced electricity, after the economic factors have been included. As an example, from case farm 1 the break-even spot price of the investment increases from SEK 0.338/kWh to SEK 0.664/kWh if self-used electricity decreases from 75% to 25%. All scenarios with different spot prices and percentage of self-used electricity show an extended payback period compared to the quote calculation. In the base price scenario with the most likely future forecast of SEK 0.65/kWh, the calculation shows a payback period between 13.5-15 years with a high degree of self-use for both case farms.That’s comparable to the quote calculation showing 6.28 years and a way shorter payback time . The graphs in the result show how little probability there is for the investment to match the payback time from the solar cell providers quote calculation, even with a high percentage of self-used electricity as those graphs show a payback time of 7 years. The conclusion of this study is that the identified economic factors have a significant impact on the facility's profitability for poultry producers and differ greatly from the quotation calculations in terms of the conditions of the farms

A temperature-dependent physiologically based model for the invasive apple snail Pomacea canaliculata

In order to set priorities in management of costly and ecosystem-damaging species, policymakers and managers need accurate predictions not only about where a specific invader may establish but also about its potential abundance at different geographical scales. This is because density or biomass per unit area of an invasive species is a key predictor of the magnitude of environmental and economic impact in the invaded habitat. Here, we present a physiologically based demographic model describing and explaining the population dynamics of a widespread freshwater invader, the golden apple snail Pomacea canaliculata, which is causing severe environmental and economic impacts in invaded wetlands and rice fields in Southeastern Asia and has also been introduced to North America and Europe. The model is based on bio-demographic functions for mortality, development and fecundity rates that are driven by water temperature for the aquatic stages (juveniles and adults) and by air temperature for the aerial egg masses. Our model has been validated against data on the current distribution in South America and Japan, and produced consistent and realistic patterns of reproduction, growth, maturation and mortality under different scenarios in accordance to what is known from real P. canaliculata populations in different regions and climates. The model further shows that P. canaliculata will use two different reproductive strategies (semelparity and iteroparity) within the potential area of establishment, a plasticity that may explain the high invasiveness of this species across a wide range of habitats with different climates. Our results also suggest that densities, and thus the magnitude of environmental and agricultural damage, will be largely different in locations with distinct climatic regimes within the potential area of establishment. We suggest that physiologically based demographic modelling of invasive species will become a valuable tool for invasive species managers

Validity and reliability of a new, short symptom rating scale in patients with persistent atrial fibrillation

<p>Abstract</p> <p>Background</p> <p>Symptoms related to atrial fibrillation and their impact on health-related quality of life (HRQoL) are often evaluated in clinical trials. However, there remains a need for a properly validated instrument. We aimed to develop and validate a short symptoms scale for patients with AF.</p> <p>Methods</p> <p>One hundred and eleven patients with a variety of symptoms related to AF were scheduled for DC cardioversion. The mean age was 67.1 ± 12.1 years, and 80% were men. The patients completed the new symptoms scale, the Toronto Symptoms Check List (SCL) and the generic Short Form 36 (SF-36) the day before the planned DC cardioversion. Compliance was excellent, with only 1 of 666 answers missing.</p> <p>Results</p> <p>One item, 'limitations in working capability', was deleted because of a low numerical response rate, as many of the patients were retired. The internal consistency reliability of the remaining six items was 0.81 (Cronbach's α). Patients scored highest in the items of 'dyspnoea on exertion', 'limitations in daily life due to AF' and 'fatigue due to AF', with scores of 4.5, 3.3 and 4.5, respectively. There was a good correlation to all relevant SF-36 domains and to the relevant questions of the SCL. The Rasch analyses showed that the items are unidimensional and that they are clearly separated and cover an adequate range. Test-retest reliability was performed in patients who failed DC and was adequate for three of six items, >0.70.</p> <p>Conclusion</p> <p>The psychometric characteristics of the new short symptoms scale were found to have satisfactory reliability and validity.</p