Fundamentals of organic agriculture

Organic agriculture can be traced back to the early 20th century, initiated by the Austrian spiritual philosopher Rudolf Steiner. It was later diversified by a number of key people, and more recent versions are guided by principles issued by the International Federation of Organic Agricultural Movements (IFOAM), founded in 1972. Organic practices were built upon the life philosophies and convictions of the founders regarding how to perceive nature. Today, those original views and ideas are considered as history. However, to understand the principles and opinions of modern organic agriculture, such as the exclusion of water-soluble inorganic fertilisers, we analysed the original ideas and arguments of the founders, who shared the common principle of relying on natural processes and methods, seen as a prerequisite for human health. For example, the British agriculturalist Sir Albert Howard, who together with Lady Eve Balfour founded the British Soil Association, claimed that healthy soils are the basis for human health on earth. In their view, healthy soils could only be obtained if the organic matter content was increased or at least maintained. Later, the German physician and microbiologist Hans-Peter Rusch together with the Swiss biologists Hans and Maria Müller, focused on applying natural principles in agriculture, driven by the conviction that nature is our master and always superior. Even though these early ideas have been abandoned or modified in modern organic agriculture, the principle of the founders regarding exclusion of synthetic compounds (fertilisers and pesticides) is still the main driver for choosing crops and pest control methods

Species richness and functional attributes of fish assemblages across a large-scale salinity gradient in shallow coastal areas

Coastal ecosystems are biologically productive, and their diversity underlies various ecosystem services to humans. However, large-scale species richness (SR) and its regulating factors remain uncertain for many organism groups, owing not least to the fact that observed SR (SRobs) depends on sample size and inventory completeness (IC). We estimated changes in SR across a natural geographical gradient using statistical rarefaction and extrapolation methods, based on a large fish species incidence dataset compiled for shallow coastal areas (<30 m depth) from Swedish fish survey databases. The data covered a ca. 1300 km north-south distance and a 12-fold salinity gradient along sub-basins of the Baltic Sea plus the Skagerrak and, depending on the sub-basin, 4 to 47 years of samplings during 1975-2021. Total fish SRobs was 144, and the observed fish species were of 74 % marine and 26 % freshwater origin. In the 10 sub-basins with sufficient data for further analysis, IC ranged from 77 % to 98 %, implying that ca. 2 %-23 % of likely existing fish species had remained undetected. Sample coverage exceeded 98.5 %, suggesting that undetected species represented <1.5 % of incidences across the sub-basins, i.e. highly rare species. To compare sub-basins, we calculated standardized SR (SRstd) and estimated SR (SRest). Sub-basin-specific SRest varied between 35 +/- 7 (SE) and 109 +/- 6 fish species, being ca. 3 times higher in the most saline (salinity 29-32) compared to the least saline sub-basins (salinity < 3). Analysis of functional attributes showed that differences with decreasing salinity particularly reflected a decreasing SR of benthic and demersal fish, of piscivores and invertivores, and of marine migratory species. We conclude that, if climate change continues causing an upper-layer freshening of the Baltic Sea, this may influence the SR, community composition and functional characteristics of fish, which in turn may affect ecosystem processes such as benthic-pelagic coupling and connectivity between coastal and open-sea areas

Cross-correlations in scaling analyses of phase transitions

Thermal or finite-size scaling analyses of importance sampling Monte Carlo time series in the vicinity of phase transition points often combine different estimates for the same quantity, such as a critical exponent, with the intent to reduce statistical fluctuations. We point out that the origin of such estimates in the same time series results in often pronounced cross-correlations which are usually ignored even in high-precision studies, generically leading to significant underestimation of statistical fluctuations. We suggest to use a simple extension of the conventional analysis taking correlation effects into account, which leads to improved estimators with often substantially reduced statistical fluctuations at almost no extra cost in terms of computation time.Comment: 4 pages, RevTEX4, 3 tables, 1 figur

The Fate of Firms: Explaining Mergers and Bankruptcies

Using a uniquely complete data set of more than 50,000 observations of approximately 16,000 corporations, we test theories that seek to explain which firms become merger targets and which firms go bankrupt. We find that merger activity is much greater during prosperous periods than during recessions. In bad economic times, firms in industries with high bankruptcy rates are less likely to file for bankruptcy than they are in better years, supporting the market illiquidity arguments made by Shleifer and Vishny (1992). At the firm level, we find that, among poorly performing firms, the likelihood of merger increases with poorer performance, but among better performing firms, the relation is reversed and chances of merger increase with better performance. Such a changing relation has not been detected in prior merger studies. We also find that low-growth, resource-rich firms are prime acquisition targets and that firms’ debt capacity relates negatively to the likelihood of a merger. Debt-related variables, leverage and secured debt, play an especially prominent role in distinguishing between which firms merge and which firms go bankrupt

Sense of coherence: definition and explanation

The present study is one of a few that have used "sense of coherence" (SOC) as a dependent variable in an explanatory model. After studying three different samples - 680 students, 180 parents and 315 couples - we conclude that family relational and psychopathological variables contribute significantly to the explanation of SOC (explained variance between 10-27 and 26-50 per cent). In total, we obtained an explained variance of between 42 and 64 per cent. This leads us to the conclusion that in all three samples, SOC is multifaceted and thereby is more than simply an opposite state to depression. Context may play an important part in the explanation of SOC

Värphöns

In this degree project we wanted to investigate if there are any possibilities to get a higher income from grain growing by giving the grain to hens instead of selling it. We were also wondering if the manure has any value or if it only cost the egg producer money. If the egg producer cultivate his own grain and is able to store it in layer is there quite much money to earn. Expensive pasture makes it profitability to pay up to 1,35 Swedish crowns for a kilo of wheat. In our calculating we've used calculation from the company Lantmännen. This high price for grain opens also the possibility to make a deal with any neighbour if the egg producer is unable to grow his own grain. From a hen house that holds 20 000 hens comes about 1100 cubic meters of manure a year. This little quantity doesn't carry the costs of an expensive dung spreader. Financial the egg producer shall hire that service. It is difficult to decide the manure value. It depends on which fertilizer you compare with. In this degree project we have compared the manure with three different fertilizers. We have also interviewed five egg producers that value the manure different.Bakgrunden till detta arbete har varit att se om det finns någon ekonomisk vinning för en växtodlingsgård att investera i ett värphönsstall. De frågor som vi belyst är om spannmålen får något mervärde genom att ge det till hönsen som foder istället för att sälja den. Vi har också undersökt om gödseln är en resurs eller bara kostnader för äggproducenten. Har man tillgång till egen lagringskapacitet som dessutom är salmonellaklassad är det ingen tvekan om att det går att räkna upp spannmålspriset mycket. Vi har jämfört lantmännens kompfodermodell där man köper ett halvkoncentrat som sedan kan blandas med 36 % egen spannmål, gentemot ett färdigt fullfoder. Ekonomiskt visar detta att man med dagens foderpriser kan betala 1,35 kr/kg för spannmålen. Har man ingen egenproducerad spannmål visar detta att det alldeles säkert kan finnas någon granne som borde vara intresserad av att leverera hans spannmål till äggproducenten för ett så högt pris. Enligt våra kalkyler tjänar äggproducenten även på att köpa spannmål från lantmännen vid ett normalpris på ca 1,20 kr/kg. Vid ett kilopris på 1,35 kr för spannmålen krävs det en besättning på 3439 höns för att de extrainvesteringar som krävs skall förränta sig. Gödselvärdet har varit svårare att bestämma då många faktorer spelar in. Enligt intervjuer som vi gjort med äggproducenter menar dessa att gödseln varierar i näringsvärde beroende på uppfödningssätt och mellan omgångar. Vid frigående inhysning går gödseln att sälja som ekologisk gödsel men koncentrationen blir lägre eftersom strömedel blandas in med gödseln. Ekonomiskt har vi jämfört med tre olika handelsgödselmedel och det framräknade värdet på gödseln varierar med priserna på handelsgödseltyp. Att investera i en egen stallgödselspridare bär sig inte vid en anläggning som inhyser 20 000 höns. Från ett stall i den storleken får man endast ut cirka 1100 kubikmeter gödsel om året och därför ska man rent ekonomiskt leja in stallgödselspridare vid utkörning av gödseln

Two photon annihilation of Kaluza-Klein dark matter

We investigate the fermionic one-loop cross section for the two photon annihilation of Kaluza-Klein (KK) dark matter particles in a model of universal extra dimensions (UED). This process gives a nearly mono-energetic gamma-ray line with energy equal to the KK dark matter particle mass. We find that the cross section is large enough that if a continuum signature is detected, the energy distribution of gamma-rays should end at the particle mass with a peak that is visible for an energy resolution of the detector at the percent level. This would give an unmistakable signature of a dark matter origin of the gamma-rays, and a unique determination of the dark matter particle mass, which in the case studied should be around 800 GeV. Unlike the situation for supersymmetric models where the two-gamma peak may or may not be visible depending on parameters, this feature seems to be quite robust in UED models, and should be similar in other models where annihilation into fermions is not helicity suppressed. The observability of the signal still depends on largely unknown astrophysical parameters related to the structure of the dark matter halo. If the dark matter near the galactic center is adiabatically contracted by the central star cluster, or if the dark matter halo has substructure surviving tidal effects, prospects for detection look promising.Comment: 17 pages, 3 figures; slightly revised versio