The Russia-Ukraine conflict: lessons for europeans from a polish perspective

O corrente conflito russo-ucraniano alterou novamente o destino da Europa do Leste. No entanto, esta crise deve também ser considerada como um fator perturbador da segurança Europeia. Toda a arquitetura da segurança Europeia foi afetada com a instabilidade do flanco oriental do continente. Se este conflito não servir como um fator unificador da comunidade transatlântica, poderá ser um prenúncio de difíceis tempos vindouros. Acresce, ainda, que este perigo poder-se-á tornar particularmente grave caso se instale a perceção de que a NATO perdeu a sua credibilidade para dissuadir ameaças e a União Europeia a sua capacidade como potência normativa para estimular mudanças no sistema internacional. Inicialmente, este artigo apresenta cinco lições fundamentais que deverão ser retiradas do conflito russo-ucraniano de forma a conter eventuais desafios e ameaças para a Europa. Posteriormente, serão abordadas quatro recomendações que constituem uma base para um plano de ação de políticas securitárias sólidas e de longo prazo como resposta a este conflito.info:eu-repo/semantics/publishedVersio

Crossing barriers in planetesimal formation: The growth of mm-dust aggregates with large constituent grains

Collisions of mm-size dust aggregates play a crucial role in the early phases of planet formation. We developed a laboratory setup to observe collisions of dust aggregates levitating at mbar pressures and elevated temperatures of 800 K. We report on collisions between basalt dust aggregates of from 0.3 to 5 mm in size at velocities between 0.1 and 15 cm/s. Individual grains are smaller than 25 \mum in size. We find that for all impact energies in the studied range sticking occurs at a probability of 32.1 \pm 2.5% on average. In general, the sticking probability decreases with increasing impact parameter. The sticking probability increases with energy density (impact energy per contact area). We also observe collisions of aggregates that were formed by a previous sticking of two larger aggregates. Partners of these aggregates can be detached by a second collision with a probability of on average 19.8 \pm 4.0%. The measured accretion efficiencies are remarkably high compared to other experimental results. We attribute this to the rel. large dust grains used in our experiments, which make aggregates more susceptible to restructuring and energy dissipation. Collisional hardening by compaction might not occur as the aggregates are already very compact with only 54 \pm 1% porosity. The disassembly of previously grown aggregates in collisions might stall further aggregate growth. However, owing to the levitation technique and the limited data statistics, no conclusive statement about this aspect can yet be given. We find that the detachment efficiency decreases with increasing velocities and accretion dominates in the higher velocity range. For high accretion efficiencies, our experiments suggest that continued growth in the mm-range with larger constituent grains would be a viable way to produce larger aggregates, which might in turn form the seeds to proceed to growing planetesimals.Comment: 9 pages, 20 figure

Very high energy gamma-ray observation of the peculiar transient event Swift J1644+57 with the MAGIC telescopes and AGILE

Context. On March 28, 2011, the BAT instrument on board the Swift satellite detected a new transient event that in the very beginning was classified as a gamma ray burst (GRB). However, the unusual X-ray flaring activity observed from a few hours up to days after the onset of the event made a different nature seem to be more likely. The long-lasting activity in the X-ray band, followed by a delayed brightening of the source in infrared and radio activity, suggested that it is better interpreted as a tidal disruption event that triggered a dormant black hole in the nucleus of the host galaxy and generated an outflowing jet of relativistic matter. Aims. Detecting a very high energy emission component from such a peculiar object would be enable us to constrain the dynamic of the emission processes and the jet model by providing information on the Doppler factor of the relativistic ejecta. Methods. The MAGIC telescopes observed the peculiar source Swift J1644+57 during the flaring phase, searching for gamma-ray emission at very-high energy (VHE, E > 100 GeV), starting observations nearly 2.5 days after the trigger time. MAGIC collected a total of 28 h of data during 12 nights. The source was observed in wobble mode during dark time at a mean zenith angle of 35 degrees. Data were reduced using a new image-cleaning algorithm, the so-called sum-cleaning, which guarantees a better noise suppression and a lower energy threshold than the standard analysis procedure. Results. No clear evidence for emission above the energy threshold of 100 GeV was found. MAGIC observations permit one to constrain the emission from the source down to 100 GeV, which favors models that explain the observed lower energy variable emission. Data analysis of simultaneous observations from AGILE, Fermi and VERITAS also provide negative detection, which additionally constrain the self-Compton emission component

GWAS meta-analysis of 16 790 patients with Barrett's oesophagus and oesophageal adenocarcinoma identifies 16 novel genetic risk loci and provides insights into disease aetiology beyond the single marker level

Objective Oesophageal cancer (EC) is the sixth leading cause of cancer-related deaths. Oesophageal adenocarcinoma (EA), with Barrett's oesophagus (BE) as a precursor lesion, is the most prevalent EC subtype in the Western world. This study aims to contribute to better understand the genetic causes of BE/EA by leveraging genome wide association studies (GWAS), genetic correlation analyses and polygenic risk modelling. Design We combined data from previous GWAS with new cohorts, increasing the sample size to 16 790 BE/EA cases and 32 476 controls. We also carried out a transcriptome wide association study (TWAS) using expression data from disease-relevant tissues to identify BE/EA candidate genes. To investigate the relationship with reported BE/EA risk factors, a linkage disequilibrium score regression (LDSR) analysis was performed. BE/EA risk models were developed combining clinical/lifestyle risk factors with polygenic risk scores (PRS) derived from the GWAS meta-analysis. Results The GWAS meta-analysis identified 27 BE and/or EA risk loci, 11 of which were novel. The TWAS identified promising BE/EA candidate genes at seven GWAS loci and at five additional risk loci. The LDSR analysis led to the identification of novel genetic correlations and pointed to differences in BE and EA aetiology. Gastro-oesophageal reflux disease appeared to contribute stronger to the metaplastic BE transformation than to EA development. Finally, combining PRS with BE/EA risk factors improved the performance of the risk models. Conclusion Our findings provide further insights into BE/EA aetiology and its relationship to risk factors. The results lay the foundation for future follow-up studies to identify underlying disease mechanisms and improving risk prediction

Large and deep perialpine lakes: a paleolimnological perspective for the advance of ecosystem science

Large perialpine lakes represent important components of the Alpine landscape. Due to their piedmont location in the most densely populated regions of the Alps, they play a crucial socio-economic role as resource for drinking water, irrigation, industry, tourism, hydroelectric production, and biodiversity conservation. These uses expose perialpine lakes to multiple human pressure, while the extension of their catchment to the glacial Alpine range make them particularly exposed to the consequences of global warming. Limnological surveys outlined coherent responses by perialpine lakes to the massive nutrient enrichment during the 1950s-1970s, while recent development is rather heterogeneous. Past and ongoing paleolimnological studies confirmed the coherence of the lakes’ evolution within a secular perspective, but outlined individual trends as resulting from local management policies, lake morphology, and superimposed effects of climate change. A review of the paleolimnological literature published from 1975 to April 2017on perialpine lakes of different lake districts north and south of the Alps, was performed aiming at reviewing current knowledge of large and deep perialpine lakes due to sediment studies, and at summarizing how paleolimnological studies can contribute in defining past ecological status and in outlining lake sensitivity to current and future human impacts. This is particularly important when defining reference conditions, as inappropriate restoration targets might prove to become unachievable within the present context of global change. The review outlined an heterogeneous distribution of amount and topics of sediment studies among perialpine lake districts as well as knowledge gaps on the long term evolution of perialpine lakes