Photon number dependent afterpulsing in superconducting nanostrip single-photon detectors

Superconducting nanostrip single-photon detectors (SNSPDs) are widespread tools in photonic quantum technologies. Here, we study the afterpulsing phenomenon in commercial SNSPDs exhibiting significant levels of afterpulses even at low counting rates. We find different contributions, where the probability of an afterpulse is not a constant but depends on the mean number of photons per light pulse including mean numbers much less than 1. Our observations exclude the electrical circuit as the primary cause of the main contribution to the observed afterpulsing probability, which exhibits a strong dependence on mean photon number. We propose a phenomenological model that qualitatively explains our findings via the introduction of slowly relaxing “afterpulsing centers,” storing the absorbed photons’ energy for several tens of nanoseconds. We conjecture that two-level systems in amorphous materials are physical candidates for the role of such afterpulsing centers

Lack of Brain Serotonin Affects Feeding and Differentiation of Newborn Cells in the Adult Hypothalamus

Serotonin (5-HT) is a crucial signal in the neurogenic niche microenvironment. Dysregulation of the 5-HT system leads to mood disorders but also to changes in appetite and metabolic rate. Tryptophan hydroxylase 2-deficient (Tph2-/-) mice depleted of brain 5-HT display alterations in these parameters, e.g., increased food consumption, modest impairment of sleep and respiration accompanied by a less anxious phenotype. The newly discovered neural stem cell niche of the adult hypothalamus has potential implications of mediating stress responses and homeostatic functions. Using Tph2-/- mice, we explore stem cell behavior and cell genesis in the adult hypothalamus. Specifically, we examine precursor cell proliferation and survival in Tph2-/- mice at baseline and following Western-type diet (WD). Our results show a decline in BrdU numbers with aging in the absence of 5-HT. Furthermore, wild type mice under dietary challenge decrease cell proliferation and survival in the hypothalamic niche. In contrast, increased high-calorie food intake by Tph2-/- mice does not come along with alterations in cell numbers. However, lack of brain 5-HT results in a shift of cell phenotypes that was abolished under WD. We conclude that precursor cells in the hypothalamus retain fate plasticity and respond to environmental challenges. A novel link between 5-HT signaling and cell genesis in the hypothalamus could be exploited as therapeutic target in metabolic disease

Partial restoration of the actin cytoskeleton in transformed Syrian hamster fibroblasts selected for low levels of ‘typical’ multidrug resistance

AbstractTwo independent colchicine (CLC)-resistant sublines of Rous sarcoma virus-transformed Syrian hamster flbroblasts were isolated. Each subline represented variants with 11- and 12.4-fold resistance, respectively, their 23- and 23.7-fold resistant descendants, as well as variants cultured in CLC-free medium for 10 months without loss of resistance. All variants demonstrated ‘typical’ multidrug resistance. The parental cells contained actin in dispersed form, as determined by rhodamine-phalloidin staining. In contrast, already in 11- and 12.4-fold resistant sublines up to 30% of cells demonstrated restored stress fibers. Cultivation in CLC-free medium leads to the accumulation of cells with a partially restored actin cytoskeleton. Putative mechanisms of up-regulation of stress fiber assembly in cells with P-glycoprotein-mediated multidrug resistance are discussed

Selection of an Ensemble of Atmospheric and Oceanic General Circulation Models of the CMIP-6 Project for estimating possible runoff changes in the Volga and Kama basins

In modern conditions of climate change and increasing pressure on water resources, river forecasting is becoming one of the urgent tasks of rational water use. The main tool for long-term climate characteristics prediction are the Atmospheric and Oceanic General Circulation Models (AOGCM). In this paper, we assessed the quality of a number of climatic characteristics by the CMIP-6 (Coupled Model Intercomparison Project, Phase 6) AOGCMs for the Volga and Kama basins in order to access the possibility of their use to river runoff in the 21st century forecasting. A comparison was made of the data produced by the models for the period 1985-2014 and ERA5 reanalysis data (temperature and precipitation) as well as with observational data on river runoff. The reproduction error of the average values, standard deviations, and the coincidence of series trends evaluated. It is shown that the models demonstrate very different quality of the reproduction of water balance characteristics results. When using these models to predict possible changes in river flow in the future, it is necessary to take into account these uncertainties and apply methods to reduce the impact of systematic errors

Biological resources of Lake Kroshnozero (North-West of Russia)

A comprehensive analysis of plankton and benthic communities, composition, structure and quantitative characteristics indicate that the ecosystem of Lake Kroshnozero has a eutrophic status or a transitional one between the β-mesotrophic and α-eutrophic. Plankton communities are in a stable state and provide a sustainable food base for planktivores fishes. A slight decrease in the quantitative indicators of benthos is possibly due to the methodological features of sampling and the underestimation of littoral communities. The composition and structure of benthic communities have been preserved since previous studies in the 50-90s of the last century. The ichthyofauna of Kroshnozero includes 13 fish species. Whitefish, zander, and vendace are fish of commercial importance. Fish of secondary importance are bream, perch, ruff, roach, and pike. Fish such as bleak, grayling sculpin, and burbot are relatively rare and do not serve as objects of fishing. Model calculations of fish productivity of planktivores, benthophages and predatory fish, taking into account losses to 2.3 kcal/m2 per season or 22.6 kg/ha. The average modelled ichthyomass is 4.6 kg/ha. Possible catches are one third of fish productivity equal to 7.5 kg/ha. To improve the quality and quantity of commercial stocks, recommendations are given to preserve the conditions for the reproduction and growth of valuable fish

Gfra1 Underexpression Causes Hirschsprung's Disease and Associated Enterocolitis in Mice

BACKGROUND & AIMS: RET, the receptor for the glial cell line-derived neurotrophic factor (GDNF) family ligands, is the most frequently mutated gene in congenital aganglionic megacolon or Hirschsprung's disease (HSCR). The leading cause of mortality in HSCR is HSCR-associated enterocolitis (HAEC), which is characterized by altered mucin composition, mucin retention, bacterial adhesion to enterocytes, and epithelial damage, although the order of these events is obscure. In mice, loss of GDNF signaling leads to a severely underdeveloped enteric nervous system and neonatally fatal kidney agenesis, thereby precluding the use of these mice for modeling postnatal HSCR and HAEC. Our aim was to generate a postnatally viable mouse model for HSCR/HAEC and analyze HAEC etiology. METHODS: GDNF family receptor alpha-1 (GFRa1) hypomorphic mice were generated by placing a selectable marker gene in the sixth intron of the Gfra1 locus using gene targeting in mouse embryonic stem cells. RESULTS: We report that 70%-80% reduction in GDNF co-receptor GFRa1 expression levels in mice results in HSCR and HAEC, leading to death within the first 25 postnatal days. These mice mirror the disease progression and histopathologic findings in children with untreated HSCR/HAEC. CONCLUSIONS: In GFRa1 hypomorphic mice, HAEC proceeds from goblet cell dysplasia, with abnormal mucin production and retention, to epithelial damage. Microbial enterocyte adherence and tissue invasion are late events and therefore unlikely to be the primary cause of HAEC. These results suggest that goblet cells may be a potential target for preventative treatment and that reduced expression of GFRa1 may contribute to HSCR susceptibility.Peer reviewe

Developing the accounting concept in the public sector

The main goal of this study is to develop an accounting concept for the public administration sector of the Russian Federation with state (municipal) institutions as an example. To fulfill this task, the specifics of the state (municipal) institutions were explored, the international practice of arranging accounting in the public sector was analyzed, and the current state of the information and administration function of accounting in the institutions under study was examined. Because of the analysis, specific proposals for the development of the information function of accounting were developed through the application of the accounting policy template and the development of management accounting for obtaining information for internal users. Regarding the development of the control function of accounting in state (municipal) institutions, the use of a risk map, a register of risks and other administration tools and procedures was justified. The scientific novelty of the study is in systematization of the problems existing in the formation of the accounting system in state (municipal) institutions and in the development of proposals to improve its efficiency.peer-reviewe

Electron energy relaxation in disordered superconducting NbN films

We report on the inelastic-scattering rate of electrons on phonons and relaxation of electron energy studied by means of magnetoconductance, and photoresponse, respectively, in a series of strongly disordered superconducting NbN films. The studied films with thicknesses in the range from 3 to 33 nm are characterized by different Ioffe-Regel parameters but an almost constant product q_Tl(q_T is the wave vector of thermal phonons and l is the elastic mean free path of electrons). In the temperature range 14-30 K, the electron-phonon scattering rates obey temperature dependencies close to the power law 1/\tau_{e-ph} \sim T^n with the exponents n = 3.2-3.8. We found that in this temperature range \tau_{e-ph} and n of studied films vary weakly with the thickness and square resistance. At 10 K electron-phonon scattering times are in the range 11.9-17.5 ps. The data extracted from magnetoconductance measurements were used to describe the experimental photoresponse with the two-temperature model. For thick films, the photoresponse is reasonably well described without fitting parameters, however, for thinner films, the fit requires a smaller heat capacity of phonons. We attribute this finding to the reduced density of phonon states in thin films at low temperatures. We also show that the estimated Debye temperature in the studied NbN films is noticeably smaller than in bulk material.Comment: 23 pages, 6 figure