Is there an influence of solar activity on the North Atlantic Oscillation? : a literature study of the forcing factors behind the North Atlantic Oscillation

Nordatlantiska Oscillationen (NAO) är ett atmosfäriskt cirkulationsfenomen som kännetecknas av skillnader i havsnivåtryck mellan högtrycksområdet vid Azorerna och lågtrycksområdet över Island. NAO varierar mellan en positiv och negativ fas beroende på hur väl utvecklade dessa högtrycksområden är. NAO har visat sig ha stor påverkan på vinterklimatet på norra halvklotet eftersom den påverkar temperaturer, stormar och nederbörd över Atlantområdet. På senare år har flera studier publicerats med teorier angående vilka bakomliggande faktorer som driver NAO. Denna kandidatuppsats är en litteraturstudie med syfte att sammanfatta de mest framstående teorierna kring de pådrivande mekanismerna bakom NAO, med främsta fokus inriktat på effekterna av variationer i solaktivitet. Det är debatterat huruvida NAO drivs av variationer i solaktivitet. NAO har visat sig korrelera med variationer i solaktivitet under den senare halvan av 1900-talet men under första halvan av 1900-talet syns ingen korrelation. Studier visar att variationer i solaktivitet kan leda till uppvärmning av stratosfären. På grund av ökade temperaturer i stratosfären förstärks de stratosfäriska vindar vilka sedan kan spridas ner till troposfären. Detta leder till ökade västvindar och en positiv NAO-fas. Forskning visar även att variationer i solinstrålning leder till blockerande högtryck. Dessa förändrar vind- och stormriktningen över Atlanten, vilket leder till en negativ NAO-fas. Förutom variationer i solaktivitet har det föreslagits att NAO drivs av skillnader i havsytetemperaturer, havsis och vulkanisk aktivitet.The North Atlantic Oscillation (NAO) is an atmospheric circulation phenomenon, characterized by differences in sea level pressure between the Azores high- and the Icelandic low pressure systems. The NAO fluc-tuates between a positive and a negative phase depending on how well developed these pressure systems are. The NAO has a great impact on northern hemisphere winter climate since it affects temperatures, storms and precipita-tion over the Atlantic area. In recent years various studies have investigated the underlying mechanisms which cause the NAO to oscillate. This paper is a literature study with the aim to summarize the most prominent theories of the forcing mechanisms behind the NAO, with a main focus on the effects of variations in solar activity. Differ-ent studies disagree on whether the NAO is forced by solar activity variations or not. While the NAO has been shown to correlate with variations in solar activity in the second half of the 20th century, this correlation is less clear during the first half of the 20th century. Several studies indicate that variations in solar activity might affect the NAO by inducing stratospheric circulation changes which are propagated down on the troposphere. During high solar activity years this enhances the westerly winds and causes a positive NAO. It is also suggested that the varia-tions in solar irradiance cause atmospheric blockings to occur. These blockings, that interrupt winds and storm tracks over the Atlantic, is more persistent during low solar activity years and is associated with a negative NAO. Except variations in solar activity, it has been suggested that the NAO varies due to variations in sea surface tem-peratures, sea ice and volcanic activity

Blombesökare i blomremsor : vilka blomarter är de mest attraktiva?

Flower strips can be a helpful tool when it comes to increase pollination, pest control and farmland diversity. Different flower species have different attributes such as colour, odours and depth of the corolla tubes and this determines which beneficial organisms will be attracted to that flower species. In order to discern which are the most attractive flower species for pollinators in Sweden, we surveyed 30 different plant species in a field trial in Uppland. All the pollinators visiting the flowers were observed and collected. In total 264 hoverflies and 484 bumblebees were collected during the season. The most attractive flower species overall were Phacelia tanacetifolia, Cyanus segetum, Coriandrum sativum and Fagopyrum esculentum. Hoverflies preferred flower species with shorter corolla tubes, such as Coriandrum sativum and Ammi majus, and bumblebees and honeybees preferred flower species with a bit longer corolla tubes such as Trifolium spp. and Vicia sativa. Flower strips can benefit the biological diversity by maintaining natural habitats for different pollinators. By using a broad variation of plant species in flower strips one can benefit ecosystem services such as pollination

Enforcement of IFRS in Sweden - Achievements for building trust to the financial information

The study was conducted through an abductive approach and a qualitative research strategy using a hermeneutic epistemological stance. The data was collected using interviews and respondents selected with a purposive sample technique. With interviews as a data collection technique, we have gathered data from five respondents representing larger listed companies, auditors from the four largest auditing firms, and from the enforcement bodies FI and OMX This thesis has found evidence suggesting that trust towards the financial statements has changed, unfortunately to the worse. Although there is a perception today among preparers (the companies) and attesters (the auditors) that the work contributes to a creation of trust, the magnitude and actual impact are hard to specify. Due to the transparency, competence and impact of the surveillance made by the former enforcement body Övervakningspanelen, there is not an increased trust towards the financial statements in comparison to the situation today

Jet Reconstruction and Graph Neural Networks in Heavy-Ion Collisions

Masteroppgave i fysikkPHYS399MAMN-PHY

Enforcement of IFRS in Sweden

Purpose: Has the trust changed for the Swedish financial reports based on IFRS standards with the enforcement work done by FI and OMX, and if so, why? This thesis has found evidence suggesting that trust towards the financial statements has changed, unfortunately to the worse. Although there is a perception today among preparers (the companies) and attesters (the auditors) that the work contributes to a creation of trust, the magnitude and actual impact are hard to specify. Due to the transparency, competence and impact of the surveillance made by the former enforcement body Övervakningspanelen, there is not an increased trust towards the financial statements in comparison to the situation today. With interviews as a data collection technique, we have gathered data from five respondents representing larger listed companies, auditors from the four largest auditing firms, and from the enforcement bodies FI and OMX. We have used theoretical perspectives related to the concept of trust in business and enforcement of IFRS in order to grasp their relations. Trust is fundamental when working with surveillance and financial statements today

Storage and on-demand release of microwaves using superconducting resonators with tunable coupling

We present a system which allows to tune the coupling between a superconducting resonator and a transmission line. This storage resonator is addressed through a second, coupling resonator, which is frequency-tunable and controlled by a magnetic flux applied to a superconducting quantum interference device (SQUID). We experimentally demonstrate that the lifetime of the storage resonator can be tuned by more than three orders of magnitude. A field can be stored for 18 {\mu}s when the coupling resonator is tuned off resonance and it can be released in 14 ns when the coupling resonator is tuned on resonance. The device allows capture, storage, and on-demand release of microwaves at a tunable rate.Comment: 5 pages, 3 figure

Resonant and off-resonant microwave signal manipulation in coupled superconducting resonators

We present an experimental demonstration as well as a theoretical model of an integrated circuit designed for the manipulation of a microwave field down to the single-photon level. The device is made of a superconducting resonator coupled to a transmission line via a second frequency-tunable resonator. The tunable resonator can be used as a tunable coupler between the fixed resonator and the transmission line. Moreover, the manipulation of the microwave field between the two resonators is possible. In particular, we demonstrate the swapping of the field from one resonator to the other by pulsing the frequency detuning between the two resonators. The behavior of the system, which determines how the device can be operated, is analyzed as a function of one key parameter of the system, the damping ratio of the coupled resonators. We show a good agreement between experiments and simulations, realized by solving a set of coupled differential equations.Comment: 10 pages, 6 figure

The Landscape of Candidate Driver Genes Differs between Male and Female Breast Cancer.

The rapidly growing collection of diverse genome-scale data from multiple tumor types sheds light on various aspects of the underlying tumor biology. With the objective to identify genes of importance for breast tumorigenesis in men and to enable comparisons with genes important for breast cancer development in women, we applied the computational framework COpy Number and EXpression In Cancer (CONEXIC) to detect candidate driver genes among all altered passenger genes. Unique to this approach is that each driver gene is associated with several gene modules that are believed to be altered by the driver. Thirty candidate drivers were found in the male breast cancers and 67 in the female breast cancers. We identified many known drivers of breast cancer and other types of cancer, in the female dataset (e.g. GATA3, CCNE1, GRB7, CDK4). In contrast, only three known cancer genes were found among male breast cancers; MAP2K4, LHP, and ZNF217. Many of the candidate drivers identified are known to be involved in processes associated with tumorigenesis, including proliferation, invasion and differentiation. One of the modules identified in male breast cancer was regulated by THY1, a gene involved in invasion and related to epithelial-mesenchymal transition. Furthermore, men with THY1 positive breast cancers had significantly inferior survival. THY1 may thus be a promising novel prognostic marker for male breast cancer. Another module identified among male breast cancers, regulated by SPAG5, was closely associated with proliferation. Our data indicate that male and female breast cancers display highly different landscapes of candidate driver genes, as only a few genes were found in common between the two. Consequently, the pathobiology of male breast cancer may differ from that of female breast cancer and can be associated with differences in prognosis; men diagnosed with breast cancer may consequently require different management and treatment strategies than women

Twin paradox with macroscopic clocks in superconducting circuits

We propose an implementation of a twin paradox scenario in superconducting circuits, with velocities as large as a few percent of the speed of light. Ultrafast modulation of the boundary conditions for the electromagnetic field in a microwave cavity simulates a clock moving at relativistic speeds. Since our cavity has a finite length, the setup allows us to investigate the role of clock size as well as interesting quantum effects on time dilation. In particular, our theoretical results show that the time dilation increases for larger cavity lengths and is shifted due to quantum particle creation.Comment: 6 pages, 3 figures. I. F. previously published as I. Fuentes-Guridi and I. Fuentes-Schulle