Effective graviton mass in de Sitter space

We calculate the effective mass of gravitational perturbations induced by the interaction of the classical gravitational field with quantum matter in the background of the Poincar\'e patch of de Sitter space. Using the Schwinger-Keldysh diagrammatic technique, the one-loop effective action is calculated and it is shown that the graviton does not acquire mass for the most symmetric Bunch-Davies state. However, we have shown that even in this case, there is a nontrivial modification of the theory at one loop in the scalar sector of gravity.Comment: 35 pages, 5 figure

Late Holocene droughts in the Fertile Crescent recorded in a speleothem from northern Iraq

Droughts have had large impacts on past and present societies. High-resolution paleoclimate data are essential to place recent droughts in a meaningful historical context and to predict regional future changes with greater accuracy. Such records, however, are very scarce in the Middle East in general, and the Fertile Crescent in particular. Here we present a 2400 year long speleothem-based multiproxy record from Gejkar Cave in northern Iraq. Oxygen and carbon isotopes and magnesium are faithful recorders of effective moisture. The new Gejkar record not only shows that droughts in 1998–2000 and 2007–2010, which have been argued to be a contributing factor to Syrian civil war, were extreme compared to the current mean climate, but they were also superimposed on a long-term aridification trend that already started around or before 950 C.E. (Common Era). This long-term trend is not captured by tree ring records and climate models, emphasizing the importance of using various paleoclimate proxy data to evaluate and improve climate models and to correctly inform policy makers about future hydroclimatic changes in this drought-prone region

Redox conditions in the Late Cretaceous Chalk Sea: the possible use of cerium anomalies as palaeoredox indicators in the Cenomanian and Turonian Chalk of England

The cerium anomalies preserved in the Chalk have been investigated as possible palaeoredox indicators of the Late Cretaceous Sea and its sediment. This has been based upon over a hundred new rare earth element analyses of selected samples and grain size fractions from the Chalk. Particular attention has been given to the methodology of differentiating between the cerium anomalies preserved in the bioclastic calcite and those in carbonate-fluorapatite preserved in the acetic acid insoluble residues of chalks. Variations in the cerium anomaly of different particle size fractions of uncemented chalks suggest that fractionation of rare earth elements between the Chalk's seawater and the various organisms that contributed skeletal material to the bioclastic calcite of the Chalk may have occurred. Post-depositional processes of calcite cementation and late diagenetic sulphidisation have had no apparent effect on the cerium anomaly of the acetic acid insoluble residues. The cerium anomalies associated with the acetic acid insoluble residues from (1) an alternating sequence of chalks and marls from Ballard Cliff (Dorset, UK) typical of Milankovitch cyclicity show a marked diagenetic pattern, whereas those from (2) non-volcanic and volcanic marls display a pattern that is best explained by the variations in the availability of phosphorus and the timing of argillisation of volcanic glass during diagenesis. The general conclusion is drawn that the cerium anomalies preserved in the Chalk can provide an insight into the changing palaeoredox conditions in the Late Cretaceous Sea as well as in the pore fluids of its sediments

SMART CITIES AND 5G NETWORKS: AN EMERGING TECHNOLOGICAL AREA?

The term “smart city” has recently become greatly widespread in academic and political discourse. Nevertheless, this is rather a marketing term that unites a number of technological (and other) areas: Internet of Things (IoT), augmented and virtual reality (AR/VR), communication networks. The latest generation of networks is essential for the development of digital ecosystems of smart cities. It has been assumed that the smart city and 5G networks form an emerging technological area. The goal of the work is to study the structure of the development and implementation of new technologies for the urban environment on the sample of 5G-based technologies. For the analysis of new technologies in the selected subject area, a study of patent landscapes and scientometric analysis of the topic field has been conducted. The object of the scientometric analysis is the study of citation patterns. The use of the patent landscape is based on the information systems and databases of patent information developed by patent offices and commercial companies and consists of visualizing the logical connections between various indicators of patent activity, on the one hand, and technological and market trends, on the other. Together, the scientometric and patent landscape show the most promising areas of technological research. The results of the study can be used in further theoretical and applied research, in the formation of government policy in research and development, as well as in decision-making in the field of urban management

Reassessing Mg/Ca temperature calibrations of <em>Neogloboquadrina pachyderma</em> (sinistral) using paired δ^44/40 and Mg/Ca measurements

The Mg/Ca temperature calibration of the polar to subpolar planktonic foraminifera Neogloboquadrina pachyderma (sinistral) (sinistral indicates left coiling) was refined by a multiproxy approach combining hydrographic temperature and salinity data with Mg/Ca, delta Ca-44/40, and delta O-18 values from Holocene Nordic seas core top samples. Reliable Mg/Ca-based temperature estimates are limited to foraminiferal tests that calcified in water masses with temperatures above similar to 3 degrees C at habitat depth. In these samples, Mg/Ca and delta Ca-44/40 values are positively correlated (Mg/Ca (mmol/mol) = 0.77 (+/- 0.22) x delta Ca-44/40 (parts per thousand SRM 915a) + 0.52 (+/- 0.12); n = 20, R-2 = 0.76). Both Mg/Ca- and delta Ca-44/40-derived temperatures projected onto their corresponding depth intervals reveal that the &quot;apparent'' calcification depth of N. pachyderma (sinistral) averaging the specimens' whole life cycle is bound to an isopycnal layer defined by water densities (sigma(t)) between 27.7 and 27.8. This implies that N. pachyderma (sinistral) prefers gradually deeper habitats with increasing sea surface temperatures, thus counterbalancing absolute temperature variations. Consequently, the total temperature range recorded in this foraminiferal species is restricted and only partly reflects environmental changes. On the basis of the new Mg/Ca, delta Ca-44/40, and delta O-18 multiproxy data set, we propose a linear Mg/Ca temperature relation for high-latitude N. pachyderma (sinistral): Mg/Ca (mmol/mol) = 0.13 (+/- 0.037) T (degrees C) + 0.35 (+/- 0.17); T &gt; 3 degrees C. In core top samples from polar waters with peak summer temperatures below similar to 3 degrees C, the temperature response in the Mg/Ca and delta Ca-44/40 proxy signal is inversed and poorly correlated. Both Mg/Ca- and delta Ca-44/40-derived temperature estimates pretend significantly higher calcification temperatures than maximum summer sea surface temperatures of these water masses

Intraspecific variation in recent populations of Globigerinoides ruber from the eastern Indian Ocean: evidence from test morphology and geochemistry

Abstrac

Unmovable Detection Unit of the Thermal Neutron Flux in the Source Range of the Reactor

This paper presents the results of theoretical and experimental research of the new unmovable detection unit of the thermal neutron flux in the source range of the reactor. The design features and the main parameters of this unit are also shown

Contrasting multiproxy reconstructions of surface ocean hydrography in the Agulhas Corridor and implications for the Agulhas Leakage during the last 345,000 years

Planktonic δ18O and Mg/Ca-derived sea surface temperature (SST) records from the Agulhas Corridor off South Africa display a progressive increase of SST during glacial periods of the last three climatic cycles. The SST increases of up to 4°C coincide with increased abundance of subtropical planktonic foraminiferal marker species which indicates a progressive warming due to an increased influence of subtropical waters at the core sites. Mg/Ca-derived SST maximizes during glacial maxima and glacial Terminations to values about 2.5°C above full-interglacial SST. The paired planktonic δ18O and Mg/Ca-derived SST records yield glacial seawater δ18O anomalies of up to 0.8‰, indicating measurably higher surface salinities during these periods. The SST pattern along our record is markedly different from a U37K'-derived SST record at a nearby core location in the Agulhas Corridor that displays SST maxima only during glacial Terminations. Possible explanations are lateral alkenone advection by the vigorous regional ocean currents or the development of SST contrasts during glacials in association with seasonal changes of Agulhas water transports and lateral shifts of the Agulhas retroflection. The different SST reconstructions derived from U37K' and Mg/Ca pose a significant challenge to the interpretation of the proxy records and demonstrate that the reconstruction of the Agulhas Current and interocean salt leakage is not as straightforward as previously suggested

Interlaboratory study for coral Sr/Ca and other element/Ca ratio measurements

The Sr/Ca ratio of coral aragonite is used to reconstruct past sea surface temperature (SST). Twentyone laboratories took part in an interlaboratory study of coral Sr/Ca measurements. Results show interlaboratory bias can be significant, and in the extreme case could result in a range in SST estimates of 7°C. However, most of the data fall within a narrower range and the Porites coral reference material JCp- 1 is now characterized well enough to have a certified Sr/Ca value of 8.838 mmol/mol with an expanded uncertainty of 0.089 mmol/mol following International Association of Geoanalysts (IAG) guidelines. This uncertainty, at the 95% confidence level, equates to 1.5°C for SST estimates using Porites, so is approaching fitness for purpose. The comparable median within laboratory error is <0.5°C. This difference in uncertainties illustrates the interlaboratory bias component that should be reduced through the use of reference materials like the JCp-1. There are many potential sources contributing to biases in comparative methods but traces of Sr in Ca standards and uncertainties in reference solution composition can account for half of the combined uncertainty. Consensus values that fulfil the requirements to be certified values were also obtained for Mg/Ca in JCp-1 and for Sr/Ca and Mg/Ca ratios in the JCt-1 giant clam reference material. Reference values with variable fitness for purpose have also been obtained for Li/Ca, B/Ca, Ba/Ca, and U/Ca in both reference materials. In future, studies reporting coral element/Ca data should also report the average value obtained for a reference material such as the JCp-1