Fermions via spinor-valued one-forms

Spinor-valued one-forms (Rarita-Schwinger fields) are normally used in the context of supergravity, where they describe spin 3/2 particles (gravitinos). Indeed, when decomposed into irreducible representations of the Lorentz group such a field contains both a spin 1/2 and a spin 3/2 component, and the Rarita-Schwinger Lagrangian is designed to make only the spin 3/2 propagate. We point out that the opposite construction is also possible, and give a spinor-valued one-form field Lagrangian that describes a propagating spin 1/2 particle.Comment: 23 pages, no figure

Remarks on Barbero-Immirzi parameter as a field

We revisit a propagating torsion gravity theory obtained by introducing a field coupled to the Holst term in the first-order Einstein-Cartan action. The resulting theory has second order field equations, no adjustable coupling constants, and one more propagating degree of freedom as compared to general relativity. When no fermions are present the theory is known to be equivalent to that of a single massless scalar field canonically coupled to gravity. We extend this result to the case with fermions and obtain an effective interaction between the scalar field and the fermionic currents. We also describe a version of the theory with a potential for the scalar field and discuss whether it can be interpreted as the inflaton.Comment: (v1) 5 pages (v2) 6 pages, title changed to avoid misreadings, references and further comments added (v3) 10 pages, treatment of fermions added (v4) published versio

Gravity-Yang-Mills-Higgs unification by enlarging the gauge group

We revisit an old idea that gravity can be unified with Yang-Mills theory by enlarging the gauge group of gravity formulated as gauge theory. Our starting point is an action that describes a generally covariant gauge theory for a group G. The Minkowski background breaks the gauge group by selecting in it a preferred gravitational SU(2) subgroup. We expand the action around this background and find the spectrum of linearized theory to consist of the usual gravitons plus Yang-Mills fields charged under the centralizer of the SU(2) in G. In addition, there is a set of Higgs fields that are charged both under the gravitational and Yang-Mills subgroups. These fields are generically massive and interact with both gravity and Yang-Mills sector in the standard way. The arising interaction of the Yang-Mills sector with gravity is also standard. Parameters such as the Yang-Mills coupling constant and Higgs mass arise from the potential function defining the theory. Both are realistic in the sense explained in the paper.Comment: 61 pages, no figures (v2) some typos correcte

Geography of European migration

In recent decades, the role of international migration has increased dramatically in most European countries. The growth in migration has made some authors proclaim the beginning of a second Migration Period that could transform the social and cultural identity of Europe. The article presents an analysis of international migration geography in Europe in the last twenty-five years. The authors identify the main trends in migration, provide migration profiles of European countries, and propose a classification based on the recent changes in the migrant stock. Changes in the migrant stock (total emigration and immigration) reflect the level of involvement in international and global processes. They can serve as an indicator of a country's attractiveness for both foreigners and the country’s citizens. The study shows that European countries are increasingly split into "immigrant" and "emigrant" states. The authors describe spatial patterns of migration. The volume and localisation of migration flows in Europe are affected not only by cultural and historical circumstance, such as a colonial past or a common language. The scale of immigrant influx often does not depend on a donor country's demographic potential or the level of its socio-economic development. The links between the place of origin and destination are often more complex than it might initially seem. The authors stress the importance of a differentiated immigration policy taking into account ethnic and cultural features of host societies

Migration flows in Europe: space and time transformation

One of the key manifestations of globalisation is an increase in the spatial mobility of population involving growing numbers of people into international migration processes. This article is an attempt to assess the density of migration connections between European states based on the 1990-2015 quantitative data. An analysis of migration flows and relevant net migration and net migration and migration localisation at the national and regional levels makes it possible to identify key trends in the spatial and temporal transformation of this phenomenon on the European continent. Calculations suggest that an increase in migration has not narrowed the gap between source and recipient countries but, on the contrary, it has made it more pronounced over the recent decades. The article presents an attempt at classifying European countries by the direction and intensity of migration connections and stresses the impact of international migration on the demographic and sociocultural situation in different European states

Evaluation of Immune Status in Two Cohorts of Atlantic Salmon Raised in Different Aquaculture Systems (Case Study)

publishedVersio

Сравнительный анализ коллекций научных журналов

Разработан подход для сравнительного анализа коллекций научных журналов на основе анализа графа соавторств и модели текста. Использование временных рядов метрик графа соавторства позволило провести анализ тенденций в развитии коллабораций авторов журнала. Модель текста была построена с помощью методов машинного обучения. При помощи модели текста была произведена классификация контента журналов для выявления степени аутентичности различных журналов и различных выпусков одного журнала. Разработана метрика Коэффициент контентной аутентичности, позволяющая количественно оценивать аутентичность коллекций журналов в сравнении. Сравнительный тематический анализ коллекций журналов выполнен с использованием тематической модели с аддитивной регуляризацией. На основании созданной тематической модели авторами построены тематические профили архивов журналов в едином тематическом базисе. Разработанный подход был применен к архивам двух журналов по тематике Ревматология за период 2000 – 2018 гг. В качестве эталона для сравнения метрик соавторств были взяты публичные наборы данных научной лаборатории SNAP Стендфордского университета. Проведено сравнение коллабораций соавторов журналов по тематике Ревматология с эталонными коллаборациями авторов. Произведено количественное сопоставление больших объемов текстов и метаданных научных статей. В результате проведенного авторами эксперимента с использованием разработанных методик показано, что контентная аутентичность выбранных журналов составляет 89%, соавторства в одном из журналов имеют ярко выраженную центральность, что является отличительной чертой редакционной политики. Наглядность и непротиворечивость полученных результатов подтверждает эффективность предложенного подхода. Разработанный в ходе эксперимента код на языке программирования Python может быть применен для сравнительного анализа других коллекций журналов на русском языке

Effect of two constant light regimens on antibody profiles and immune gene expression in Atlantic salmon following vaccination and experimental challenge with salmonid alphavirus

Before seawater transfer, farmed Atlantic salmon are subjected to treatments that may affect the immune system and susceptibility to pathogens. E.g., exposure to constant light (CL) stimulates smoltification, which prepares salmon to life in sea water, but endocrine changes in this period are associated with suppression of immune genes. Salmon are vaccinated towards end of the freshwater period to safeguard that adequate vaccine efficacy is achieved by the time the fish is transferred to sea. In the present study, we investigated how the responses to vaccination and viral infection varied depending on the time of CL onset relative to vaccination. The salmon were either exposed to CL two weeks prior to vaccination (2-PRI) or exposed to CL at the time of vaccination (0-PRI). A cohabitant challenge with salmonid alphavirus, the causative agent of pancreatic disease, was performed 9 weeks post vaccination. The immunological effects of the different light manipulation were examined at 0- and 6-weeks post vaccination, and 6 weeks post challenge. Antibody levels in serum were measured using a serological bead-based multiplex panel as well as ELISA, and 92 immune genes in heart and spleen were measured using an integrated fluidic circuit-based qPCR array for multiple gene expression. The 2-PRI group showed a moderate transcript down-regulation of genes in the heart at the time of vaccination, which were restored 6 weeks after vaccination (WPV). Conversely, at 6WPV a down-regulation was seen for the 0-PRI fish. Moreover, the 2-PRI group had significantly higher levels of antibodies binding to three of the vaccine components at 6WPV, compared to 0-PRI. In response to SAV challenge, transcription of immune genes between 2-PRI and 0-PRI was markedly dissimilar in the heart and spleen of control fish, but no difference was found between vaccinated salmon from the two CL regimens. Thus, by using labor-saving high throughput detection methods, we demonstrated that light regimens affected antibody production and transcription of immune genes in non-vaccinated and virus challenged salmon, but the differences between the light treatment groups appeared eliminated by vaccination.publishedVersio

Photoperiod in recirculation aquaculture systems and timing of seawater transfer affect seawater growth performance of Atlantic salmon (Salmo salar)

Production of Atlantic salmon smolts in recirculation aquaculture systems (RAS) is growing, and novel production protocols using continuous light in RAS are being implemented in the industry. In the present study, Atlantic Salmon parr were exposed to either a traditional protocol (short-day winter signal [12:12 L:D] for 6 weeks) or to continuous light. Both photoperiods were applied in freshwater (FW) and brackish water RAS. Salmon from all treatments were transferred to seawater pens at 200 and 600 g and grown until slaughter size. A control group was smoltified with a 6-week short-day winter signal and kept in FW until sea transfer at 100 g. Continuous light gave a higher growth rate in RAS but reduced feed intake and growth and increased feed conversion ratio during the first 8 weeks in seawater. However, at slaughter, fish exposed to continuous light was bigger than fish given a winter signal because of the higher growth rate in RAS. Slaughter weight was lowest in fish transferred to sea at 600 g, despite having the highest day-degree sum during their life span. The best performing group was the control group transferred at 100 g. All treatments handled transfer to seawater and survival and maturation were not affected by the treatments in RAS. The immune status was examined with a multigene expression assay on BioMark HD platform from parr stage to 5–7 months after seawater transfer. Overall, there was no significant effect of photoperiod or salinity on the expression of the selected immune genes. In sum, the results from this study indicate that using continuous light in RAS may have negative effects on performance shortly after transfer in fish transferred to sea at 200 g, whereas at 600 g, all treatments had reduced growth after transfer irrespective of treatment in RAS.publishedVersio