Spiders in the agricultural landscape

Spiders in agroecosystems play a role in natural pest suppression and contribute to biodiversity. In this thesis I have investigated if and when spiders recolonise cereal fields in spring when they have the potential to suppress establishing pest aphid populations. Furthermore, the influence of different environmental factors on spiders has been investigated to understand how it might be possible to provide suitable conditions for enhancement of their populations. Linyphiid spiders recolonised fields after being negatively affected by sowing in spring, while lycosid spiders were unaffected. Conversely, lycosids showed a recolonisation in winter cereals after overwintering, but not linyphiids. But linyphiid migratory patterns also differed over time, because they were positively influenced by landscape heterogeneity in the beginning of spring but not at the end. Diversity of lycosid and linyphiid spiders was positively influenced by perennial crops and forest in the surrounding landscape. Field margins were found to be a key habitat for the diversity of both spider families. Lycosid abundance was affected on the habitat scale and linyphiid abundance on the larger landscape scale, which can be explained by the families' different modes of dispersal. Farming systems, conventional or organic, contained different compositions of lycosid and linyphiid species. The dominant lycosid and linyphiid species were more abundant at organic sites. Body condition of Pardosa (Lycosidae) turned out to be superior in landscapes dominated by large fields with annual crops, irrespective of farming system, perhaps because of less competition for available resources. This thesis provides evidence that spiders are present in crop fields early in spring when they have the opportunity to suppress establishing aphid pests. Different spider species were associated with different farming systems, but the abundances of the most common species were enhanced by organic management. A diverse landscape with easy access to perennial crops and field margins will augment both number of species and individuals of spiders

Evidence for Multiple Pathways to Deuterium Enhancements in Protoplanetary Disks

The distributions of deuterated molecules in protoplanetary disks are expected to depend on the molecular formation pathways. We use observations of spatially resolved DCN emission from the disk around TW Hya, acquired during ALMA Science verification with a ~3" synthesized beam, together with comparable DCO+ observations from the Submillimeter Array, to investigate differences in the radial distributions of these species and hence differences in their formation chemistry. In contrast to DCO+, which shows an increasing column density with radius, DCN is better fit by a model that is centrally peaked. We infer that DCN forms at a smaller radii and thus at higher temperatures than DCO+. This is consistent with chemical network model predictions of DCO+ formation from H2D+ at T<30 K and DCN formation from additional pathways involving CH2D+ at higher temperatures. We estimate a DCN/HCN abundance ratio of ~0.017, similar to the DCO+/HCO+ abundance ratio. Deuterium fractionation appears to be efficient at a range of temperatures in this protoplanetary disk. These results suggest caution in interpreting the range of deuterium fractions observed in Solar System bodies, as multiple formation pathways should be taken into account.Comment: accepted for publication in Ap

From the Group of Twenty to the Group of Two: The Need for Harmonizing Derivatives Regulation Between the United States and the European Union

Wireless Sensor Networks are often deployed in great numbers spanning large, sometimes hard to reach and hostile, areas with the aim of monitoring environmental conditions through the use of different sensors. Due to decreasing costs of ownership (e.g. non-proprietary protocols), recent advances in processor, radio, and memory technologies and the engineering of increasingly smaller sensing devices, the availability and area of application for wireless sensor networks have steadily been increasing. Sigma Technology Development Stockholm AB raised the question as to whether a wireless sensor network, running an open-source operating system and communicating over IPv6, could be used in the field of smart autonomous irrigation? The company also required a proof-of-concept system for demonstration purposes and to identify if the design choices made were suitable for an actual implementation. There are numerous of design decisions that have to be made when constructing an irrigation system: the back-end set-up, which irrigation algorithms to use, what hardware to choose and how to communicate? This thesis therefore focuses on the overall system design of a wireless sensor network in the field of irrigation and highlights the trade-offs being made and their pros and cons. Two improvements related to the existing technology and the proof-of-concept system are presented in this thesis. Firstly, the recommendation to use clustered self-healing routing despite claimed power consumption issues. Secondly, a new technique to minimize power consumption, by dynamically changing the sleep interval on the sensor nodes with the help of weather data. Furthermore, the proof-of-concept system is constructed and analysed to assess whether the system design choices made are valid for a real-life deployment.Trådlösa sensor nätverk används för att övervaka lokala miljöförändringar med hjälp av olika sorters sensorer. På grund av nedåtgående driftkostnader (ökad tillgänglighet av open-source mjukvara) och framsteg inom processor-, radio-, och datorminnesteknolgi har både tillgängligheten och användningsområdena för trådlösa sensornätverk stadigt ökat. Sigma Technology Development AB ställde frågan huruvida ett trådlöst sensornätverk, som använder sig av ett open-source operativsystem och kommunicerar över IPv6, kunde användas inom smart konstbevattning? Företaget ville även att ett proof-ofconcept system utvecklades för demonstration samt för att kunna avgöra om de designval som gjorts är lämpliga att använda i en verklig implementation. Det finns en mängd designval som måste göras när man konstruerar ett bevattningsystem: back-end lösningen, vilka bevattningsalogritmer som ska användas, vilken hårdvara som ska användas samt hur kommunikationen mellan noderna ska upprättas? Det här examensarbetet fokuserar därför på den övergripande systemdesigen av ett trådlöst sensornätverk inom konstbevattning, utvärderar och avgör vilka kompromisser som måste göras samt för- och nackdelarna med dessa val. Examensarbetet presenterar vidare två förbättringar på det utvecklade konceptsystemet som inte heller finns på marknanden. Först rekommenderas användandet av robusta självläkande routing protokoll trots påstådda energiförbrukningsproblem. Sedan föreslås även en teknik som minimerar energiåtgången genom att dynamiskt ändra hur länge sensornoden befinner sig i ’sleep mode’, detta med hjälp av insamlad väderdata. Slutligen så konstrueras och analyseras proof-of-concept systemet för att utvärdera om dessa designval är lämpliga för en implementering i det verkliga livet

Changing Rules of Liability in Automobile Accident Litigation

Den svenska befolkningen blir allt äldre, och denna förskjutning av befolkningssammansättningen leder till ett ökat behov av vård och omsorg. Den utmaning som detta medför för samhället motiverar att närmare studera vad som påverkar hälsan specifikt hos målgruppen äldre. Studien utgår från ett nytt datamaterial från en omfattande enkätundersökning besvarad av äldre invånare i Linköpings och Norrköpings kommun. Med Grossmans hälsoekonomiska modell som ramverk ämnar studien med kvantitativ metodik analysera vilken påverkan modellens faktorer har på äldres hälsa. För att möta syftet valde författarna att i regressionsanalys tillämpa modellen ordered probit och skatta effekterna av socioekonomiska faktorer och levnadsvanor på individers självrapporterade hälsa. Studien omfattade tio förklaringsvariabler i ett datamaterial omfattande 6 300 objekt. Resultatet visar att i en reducerad modell finns indikationer på att högre inkomst och utbildning kan leda till bättre hälsa i äldre, vilket överensstämmer med Grossmans teori. Utbildning uppvisar dock ej statistisk signifikans efter att förklaringsvariabler för levnadsvanor – rökning, fetma, alkoholmissbruk och motionering – introducerats i modellen. Författarna presenterar hypotesen att resultatet kan förklaras av att både utbildning och levnadsvanor fångas upp av en bakomliggande variabel – individens tidspreferens. Vidare finner författarna att Linköpingsbor i överensstämmelse med tidigare jämförelser anger en högre hälsonivå än Norrköpingsbor. Variabeln kommuntillhörighet visar sig vara signifikant efter kontroll av samtliga av studiens förklaringsvariabler, vilket kan tyda på en underliggande skillnad mellan kommunerna med avseende på kultur och socialt arv bortsett från effekter av levnadsvanor, utbildning och inkomstnivå

Towards reason: political disputes, public attention and the use of expert knowledge in policymaking

This article examines expert knowledge utilization in public policy processes. We study how much expert knowledge is employed and the extent to which decision-makers deliberate on the information provided by the experts, under various conditions of political disputes and public attention. We suggest four hypotheses. It is proposed that expert knowledge will be used more, but that there will be less deliberation in situations of political disputes. It is also suggested that expert knowledge will be consulted more and the decision-makers will take a more deliberative approach when there is a lot of attention from citizens. Our empirical findings, based on original data from local politics in Sweden, are in line with the hypotheses. The findings highlight the importance of both studying the extent of expert knowledge use and the way expertise is utilized. Another important insight is that politics seem to matter in relation to the role expert knowledge plays in public policymaking.Expert knowledge; Public policy; Political disputes; Public attention; Deliberation; Local government Sweden

Tentative Detection of Deuterated Methane toward the Low-Mass Protostar IRAS 04368+2557 in L1527

The millimeter-wave rotational transition line ($J_K = 1_0 - 0_0$) of deuterated methane CH$_3$D has tentatively been detected toward the low-mass Class 0 protostar IRAS 04368+2557 in L1527 with the Heinrich Hertz Submillimeter Telescope. This is the first detection of CH$_3$D in interstellar clouds, if confirmed. The column density and fractional abundance of CH$_3$D are determined to be $(9.1\pm3.4) \times 10^{15}$ cm$^{-2}$ and $(3.0\pm1.1) \times 10^{-7}$, respectively, where we assume the rotational temperature of 25 K. The column density and fractional abundance of the gaseous CH$_4$ are estimated to be $(1.3-4.6) \times 10^{17}$ cm$^{-2}$ and $(4.3-15.2) \times 10^{-6}$, respectively, by adopting the molecular D/H ratios of 2--7% reported for various molecules in L1527. The fractional abundance of CH$_4$ is higher than or comparable to that found in high-mass star-forming cores by infrared observations. It is sufficiently high for triggering the efficient production of various carbon-chain molecules in a lukewarm region near the protostar, which supports the picture of the warm carbon-chain chemistry.Comment: 13 page

Unique Bernoulli g-measures

We improve and subsume the conditions of Johansson and \"Oberg [18] and Berbee [2] for uniqueness of a g-measure, i.e., a stationary distribution for chains with complete connections. In addition, we prove that these unique g-measures have Bernoulli natural extensions. In particular, we obtain a unique g-measure that has the Bernoulli property for the full shift on finitely many states under any one of the following additional assumptions. (1) \sum_{n=1}^\infty (\var_n \log g)^20$, \sum_{n=1}^\infty e^{-(\{1}{2}+\epsilon) (\var_1 \log g+...+\var_n \log g)}=\infty,$$(3)$$\var_n \log g=\ordo{\{1}{\sqrt{n}}}, \quad n\to \infty.$$ That the measure is Bernoulli in the case of (1) is new. In (2) we have an improved version of Berbee's condition (concerning uniqueness and Bernoullicity) [2], allowing the variations of log g to be essentially twice as large. Finally, (3) is an example that our main result is new both for uniqueness and for the Bernoulli property. We also conclude that we have convergence in the Wasserstein metric of the iterates of the adjoint transfer operator to the g-measure

Countable state shifts and uniqueness of g-measures

In this paper we present a new approach to studying g-measures which is based upon local absolute continuity. We extend the result in [11] that square summability of variations of g-functions ensures uniqueness of g-measures. The first extension is to the case of countably many symbols. The second extension is to some cases where $g \geq 0$, relaxing the earlier requirement in [11] that inf g>0.Comment: 11 page