Search results for "530"
showing 10 items of 1476 documents
Observation of classically 'forbidden' electromagnetic wave propagation and implications for neutrino detection.
2018
Ongoing experimental efforts in Antarctica seek to detect ultra-high energy neutrinos by measurement of radio-frequency (RF) Askaryan radiation generated by the collision of a neutrino with an ice molecule. An array of RF antennas, deployed either in-ice or in-air, is used to infer the properties of the neutrino. To evaluate their experimental sensitivity, such experiments require a refractive index model for ray tracing radio-wave trajectories from a putative in-ice neutrino interaction point to the receiving antennas; this gives the degree of signal absorption or ray bending from source to receiver. The gradient in the density profile over the upper 200 meters of Antarctic ice, coupled wi…
Volcanic climate forcing preceding the inception of the Younger Dryas: Implications for tracing the Laacher See eruption
2021
Climatic warming from the last glacial maximum to the current interglacial period was punctuated by a similar to 1300 years long cold period, commonly referred to as the Younger Dryas (YD). Several hypotheses have been proposed for the mechanism triggering the abrupt inception of the YD, including freshwater forcing, an extra-terrestrial impact, and aerosols from volcanic eruptions. Here, we use synchronised sulphate and sulphur records from both Greenland and Antarctic ice cores to reconstruct volcanic forcing between 13,200-12,800 a BPGICC05 (years before 1950 CE on the Greenland Ice Core Chronology 2005; GICC05). This continuous reconstruction of stratospheric sulphur injections highligh…
Trophic state changes can affect the importance of methane-derived carbon in aquatic food webs
2017
Methane-derived carbon, incorporated by methane-oxidizing bacteria, has been identified as a significant source of carbon in food webs of many lakes. By measuring the stable carbon isotopic composition (δ13C values) of particulate organic matter, Chironomidae andDaphniaspp. and their resting eggs (ephippia), we show that methane-derived carbon presently plays a relevant role in the food web of hypertrophic Lake De Waay, The Netherlands. Sediment geochemistry, diatom analyses and δ13C measurements of chironomid andDaphniaremains in the lake sediments indicate that oligotrophication and re-eutrophication of the lake during the twentieth century had a strong impact on in-lake oxygen availabili…
Russia-Ukraine balance of military power
2017
The Russia-Ukraine conflict is the most serious test of European security in the 21st century and the forgone conclusion is that Russia can easily prevail in the conflict, but this has not been the case. This article uses balance of military power analysis to report findings on the plausible outcome of a war between Ukraine and Russia. I report findings based on realist theoretical perspectives that indicate Russian victory is unlikely because of relative balance of power where Russia has to face multiple threats diverting its military power while Ukraine can concentrate its military power for a single purpose. The findings suggest implication for policy in Russia, Ukraine, EU and the Unite…
Comprehensive defence in Latvia – rebranding state defence and call for society's involvement
2020
Abstract This article explores how comprehensive defence has been introduced in Latvia, and focuses on society's involvement and tasks in the state defence. This approach envisages a significant change in society's relationship with the armed forces and state defence. Differently from many other countries, Latvia maintains its system without introducing conscription and instead puts efforts towards youth education in defence. Additionally, the Ministry of Defence involves different society groups and NGOs in defining their role in state defence. This article also discusses the concepts of resistance and non-collaboration as part of comprehensive defence.
Inferring causation from time series in earth system sciences
2019
The heart of the scientific enterprise is a rational effort to understand the causes behind the phenomena we observe. In large-scale complex dynamical systems such as the Earth system, real experiments are rarely feasible. However, a rapidly increasing amount of observational and simulated data opens up the use of novel data-driven causal methods beyond the commonly adopted correlation techniques. Here, we give an overview of causal inference frameworks and identify promising generic application cases common in Earth system sciences and beyond. We discuss challenges and initiate the benchmark platform causeme.net to close the gap between method users and developers.
pH-sensitive vibrational probe reveals a cytoplasmic protonated cluster in bacteriorhodopsin
2017
Infrared spectroscopy has been used in the past to probe the dynamics of internal proton transfer reactions taking place during the functional mechanism of proteins but has remained mostly silent to protonation changes in the aqueous medium. Here, by selectively monitoring vibrational changes of buffer molecules with a temporal resolution of 6 µs, we have traced proton release and uptake events in the light-driven proton-pump bacteriorhodopsin and correlate these to other molecular processes within the protein. We demonstrate that two distinct chemical entities contribute to the temporal evolution and spectral shape of the continuum band, an unusually broad band extending from 2,300 to well…
Ultrafast structural changes within a photosynthetic reaction centre
2021
Nature <London> / Physical science 589, 310 - 314 (2021). doi:10.1038/s41586-020-3000-7
Statement complementing the EFSA Scientific Opinion on application (EFSA‐GMO‐DE‐2011‐95) for the placing on the market of genetically modified maize …
2018
Abstract The GMO Panel was previously not in the position to complete the food/feed safety assessment of maize 5307 due to an inadequate 28‐day toxicity study necessary for an appropriate assessment of eCry3.1Ab protein. Following a mandate from the European Commission, the GMO Panel assessed a supplementary 28‐day toxicity study in mice on the eCry3.1Ab protein (1,000 mg/kg body weight (bw) per day) to complement its scientific opinion on application EFSA‐GMO‐DE‐2011‐95 for the placing on the market of the maize 5307 for food and feed uses, import and processing. The supplementary 28‐day toxicity study did not show adverse effects. Taking into account the previous assessment and the new in…
Rho resonance, timelike pion form factor, and implications for lattice studies of the hadronic vacuum polarization
2020
We study isospin-1 P-wave ππ scattering in lattice QCD with two flavors of O(a) improved Wilson fermions. For pion masses ranging from mπ=265 MeV to mπ=437 MeV, we determine the energy spectrum in the center-of-mass frame and in three moving frames. We obtain the scattering phase shifts using Lüscher’s finite-volume quantization condition. Fitting the dependence of the phase shifts on the scattering momentum to a Breit-Wigner form allows us to determine the corresponding ρ mass mρ and gρππ coupling. By combining the scattering phase shifts with the decay matrix element of the vector current, we calculate the timelike pion form factor, Fπ, and compare the results to the Gounaris-Sakurai repr…