162 research outputs found
Observation of Transparency of Erbium-doped Silicon nitride in photonic crystal nanobeam cavities
One-dimensional nanobeam photonic crystal cavities are fabricated in an
Er-doped amorphous silicon nitride layer. Photoluminescence from the cavities
around 1.54 um is studied at cryogenic and room temperatures at different
optical pump powers. The resonators demonstrate Purcell enhanced absorption and
emission rates, also confirmed by time-resolved measurements. Resonances
exhibit linewidth narrowing with pump power, signifying absorption bleaching
and the onset of stimulated emission in the material at both 5.5 K and room
temperature. We estimate from the cavity linewidths that Er has been pumped to
transparency at the cavity resonance wavelength.Comment: 10 pages, 7 figure
Excess mortality in Russian regions during the COVID-19 pandemic
Relevance. In Russia, there are significant regional variations in the socio-economic impact of the COVID-19 pandemic (e.g. the growth in the number of deaths ranged from 7% in Novgorod Region to 43% in the Chechen Republic). In this paper, we focus on excess mortality and the key factors that contributed to it in order to get a better understanding of reasons behind such dramatic regional variations.The research objective is to assess excess mortality due to the COVID-19 pandemic and identify the key factors influencing the growth in mortality and regional variations in this indicator.Data and methods. The paper uses the analytical, statistical and correlation methods and the statistical data on Russian regions provided by the Federal State Statistics Service (Rosstat).Results. The analysis of excess mortality in Russian regions during the COVID-19 pandemic, in particular the correlation between excess mortality and intensity of human flows, has been used to build a typology of regions. In total, the regions were divided into four groups, and for each group the main factors that contributed to the growth in mortality were identified. The research findings can be used by policy-makers to devise more efficient regional policies in response to the COVID-19 crisis
„Jesteśmy straconym pokoleniem”. Wspólnoty Żydów birobidżańskich w Izraelu: relacja z badań terenowych (lipiec 2012 r.)
“We are the lost generation”. Communities of Birobidzhan Jews in Israel: field research report (July 2012) In this article I describe the fieldwork conducted in Israel in 2012 among those who have emigrated from the Jewish Autonomous Oblast in Russia. Along with a general overview of the research I present a detailed analysis of my interlocutors’ discourses regarding the languages they speak and their attitude towards Judaism and what is commonly understood as Jewishness. I concentrate mainly on the knowledge of Yiddish (which up until now is the official language in Birobidzhan) and Hebrew, and also on the categories that define the Jewish element of identity for them
Three-dimensional topology-based analysis segments volumetric and spatiotemporal fluorescence microscopy
Image analysis techniques provide objective and reproducible statistics for interpreting microscopy data. At higher dimensions, three-dimensional (3D) volumetric and spatiotemporal data highlight additional properties and behaviors beyond the static 2D focal plane. However, increased dimensionality carries increased complexity, and existing techniques for general segmentation of 3D data are either primitive, or highly specialized to specific biological structures. Borrowing from the principles of 2D topological data analysis (TDA), we formulate a 3D segmentation algorithm that implements persistent homology to identify variations in image intensity. From this, we derive two separate variants applicable to spatial and spatiotemporal data, respectively. We demonstrate that this analysis yields both sensitive and specific results on simulated data and can distinguish prominent biological structures in fluorescence microscopy images, regardless of their shape. Furthermore, we highlight the efficacy of temporal TDA in tracking cell lineage and the frequency of cell and organelle replication
The CO integral emission by the megacity of St Petersburg as quantified from ground-based FTIR measurements combined with dispersion modelling
The anthropogenic impact is a major factor of climate change, which is highest in industrial regions and modern megacities. Megacities are a significant source of emissions of various substances into the atmosphere, including CO which is the most important anthropogenic greenhouse gas. In 2019 and 2020, the mobile experiment EMME (Emission Monitoring Mobile Experiment) was carried out on the territory of St Petersburg which is the second-largest industrial city in Russia with a population of more than 5 million people. In 2020, several measurement data sets were obtained during the lockdown period caused by the COVID-19 (COronaVIrus Disease of 2019) pandemic. One of the goals of EMME was to evaluate the CO emission from the St Petersburg agglomeration. Previously, the CO area flux has been obtained from the data of the EMME-2019 experiment using the mass balance approach. The value of the CO area flux for St Petersburg has been estimated as being 89±28 kt km yr, which is 3 times higher than the corresponding value reported in the official municipal inventory. The present study is focused on the derivation of the integral CO emission from St Petersburg by coupling the results of the EMME observational campaigns of 2019 and 2020 and the HYSPLIT (HYbrid Single-Particle Lagrangian Integrated Trajectories) model. The ODIAC (Open-Data Inventory for Anthropogenic CO) database is used as the source of the a priori information on the CO emissions for the territory of St Petersburg. The most important finding of the present study, based on the analysis of two observational campaigns, is a significantly higher CO emission from the megacity of St Petersburg compared to the data of municipal inventory, i.e. ∼75800±5400 kt yr for 2019 and ∼68400±7100 kt yr for 2020 versus ∼30 000 kt yr reported by official inventory. The comparison of the CO emissions obtained during the COVID-19 lockdown period in 2020 to the results obtained during the same period of 2019 demonstrated the decrease in emissions of 10 % or 7400 kt yr
An Oxygen Abundance Gradient into the Outer Disk of M81
The extended HI disk and tidal tails of M81 present an interesting
environment to study the effects of galaxy interaction on star formation and
chemical evolution of the outer disk of a large spiral galaxy. We present
H{\alpha} imaging of the outer disk of M81 and luminosities for 40 HII regions
out to about 3 times the optical radius. We have also obtained MMT spectra for
21 HII regions out to more than twice the optical radius. We derive strong line
oxygen abundances for all HII regions using R_{23} based and [NII]/[OII] based
calibrations and electron temperature abundances for seven regions spanning a
galactocentric distance between 5.7 and 32 kpc. We also comment on the
abundances of HII regions near KDG 61 and the "tidal dwarf" candidate HoIX. Our
results constitute the most radially extended metallicity study for M81 to
date. With this extended data set, we find an overall oxygen abundance gradient
of -0.013 dex/kpc over the entire radial range. This is significantly flatter
than what has been found in previous studies which were limited to the optical
disk. From our temperature based abundances, we find a gradient of -0.020
dex/kpc and present the possibility of a broken gradient from these data, but
note the need to obtain more temperature based abundances at intermediate
galactocentric distances (~10-20 kpc) to verify whether or not this may be the
case. We discuss our main result of a rather flat gradient for M81 in the
context of simulations and observations of abundance gradients in other
galaxies. We find that the shallow abundance gradient of M81 is likely a result
of the interaction history of this galaxy.Comment: 41 pages, 11 figures, accepted for publication in MNRA
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