23 research outputs found
Studies of the ambient light of deep Baikal waters with Baikal-GVD
The Baikal-GVD neutrino detector is a deep-underwater neutrino telescope
under construction and recently after the winter 2023 deployment it consists of
3456 optical modules attached on 96 vertical strings. This 3-dimensional array
of photo-sensors allows to observe ambient light in the vicinity of the
Baikal-GVD telescope that is associated mostly with water luminescence. Results
on time and space variations of the luminescent activity are reviewed based on
data collected in 2018-2022
Monitoring of optical properties of deep waters of Lake Baikal in 2021-2022
We present the results of the two-year (2021-2022) monitoring of absorption
and scattering lengths of light with wavelength 400-620 nm within the effective
volume of the deep underwater neutrino telescope Baikal-GVD, which were
measured by a device Baikal-5D No.2. The Baikal-5D No.2. was installed during
the 2021 winter expedition at a depth of 1180 m. The absorption and scattering
lengths were measured every week in 9 spectral points. The device Baikal-5D
No.2 also has the ability to measure detailed scattering and absorption
spectra. The data obtained make it possible to estimate the range of changes in
the absorption and scattering lengths over a sufficiently long period of time
and to investigate the relationship between the processes of changes in
absorption and scattering. An analysis was made of changes in absorption and
scattering spectra for the period 2021-2022
Search for directional associations between Baikal Gigaton Volume Detector neutrino-induced cascades and high-energy astrophysical sources
Baikal-GVD has recently published its first measurement of the diffuse
astrophysical neutrino flux, performed using high-energy cascade-like events.
We further explore the Baikal-GVD cascade dataset collected in 2018-2022, with
the aim to identify possible associations between the Baikal-GVD neutrinos and
known astrophysical sources. We leverage the relatively high angular resolution
of the Baikal-GVD neutrino telescope (2-3 deg.), made possible by the use of
liquid water as the detection medium, enabling the study of astrophysical point
sources even with cascade events. We estimate the telescope's sensitivity in
the cascade channel for high-energy astrophysical sources and refine our
analysis prescriptions using Monte-Carlo simulations. We primarily focus on
cascades with energies exceeding 100 TeV, which we employ to search for
correlation with radio-bright blazars. Although the currently limited neutrino
sample size provides no statistically significant effects, our analysis
suggests a number of possible associations with both extragalactic and Galactic
sources. Specifically, we present an analysis of an observed triplet of
neutrino candidate events in the Galactic plane, focusing on its potential
connection with certain Galactic sources, and discuss the coincidence of
cascades with several bright and flaring blazars.Comment: 10 pages, 3 figure
Large neutrino telescope Baikal-GVD: recent status
The Baikal-GVD is a deep-underwater neutrino telescope being constructed in
Lake Baikal. After the winter 2023 deployment campaign the detector consists of
3456 optical modules installed on 96 vertical strings. The status of the
detector and progress in data analysis are discussed in present report. The
Baikal-GVD data collected in 2018-2022 indicate the presence of cosmic neutrino
flux in high-energy cascade events consistent with observations by the IceCube
neutrino telescope. Analysis of track-like events results in identification of
first high-energy muon neutrino candidates. These and other results from
2018-2022 data samples are reviewed in this report
Daily 30-min exposure to artificial gravity during 60 days of bed rest does not maintain aerobic exercise capacity but mitigates some deteriorations of muscle function: results from the AGBRESA RCT
Purpose: Spaceflight impairs physical capacity. Here we assessed the protective effect of artificial gravity (AG) on aerobic exercise capacity and muscle function during bed rest, a spaceflight analogue. Methods: 24 participants (33 ± 9 years, 175 ± 9 cm, 74 ± 10 kg, 8 women) were randomly allocated to one of three groups: continuous AG (cAG), intermittent AG (iAG) or control (CTRL). All participants were subjected to 60 days of six-degree head-down tilt bed rest, and subjects of the intervention groups completed 30 min of centrifugation per day: cAG continuously and iAG for 6 × 5 min, with an acceleration of 1g at the center of mass. Physical capacity was assessed before and after bed rest via maximal voluntary contractions, cycling spiroergometry, and countermovement jumps. Results: AG had no significant effect on aerobic exercise capacity, flexor muscle function and isometric knee extension strength or rate of force development (RFD). However, AG mitigated the effects of bed rest on jumping power (group * time interaction of the rmANOVA p < 0.001; iAG − 25%, cAG − 26%, CTRL − 33%), plantar flexion strength (group * time p = 0.003; iAG − 35%, cAG − 31%, CTRL − 48%) and plantar flexion RFD (group * time p = 0.020; iAG − 28%, cAG − 12%, CTRL − 40%). Women showed more pronounced losses than men in jumping power (p < 0.001) and knee extension strength (p = 0.010). Conclusion: The AG protocols were not suitable to maintain aerobic exercise capacity, probably due to the very low cardiorespiratory demand of this intervention. However, they mitigated some losses in muscle function, potentially due to the low-intensity muscle contractions during centrifugation used to avoid presyncope
Qualitative and quantitative adaptations of muscle fibers andmuscle protein pattern to 35-days bed rest
Ten healthy sedentary subjects underwent 35-days bed rest (BR) and needle biopsy samples
of the vastus lateralis muscle were collected pre-BR and post-BR. One portion of the
biopsy was glycerinated and used to dissect individual muscle fibers, which were studied
for measuring fiber size, myosin content and myosin actin ratio by quantitative
electrophoresis. Another portion of the biopsy was immediately frozen and used to
determine myosin heavy chain (MHC) isoform distribution and to perform proteomic
analysis by two-dimensional gel electrophoresis. As expected on the basis of previous
findings, muscle fibers were found to go through a significant degree of atrophy. Myosin
concentration was found to be lower post-BR than pre-BR in individual muscle fibers,
whereas in the same fibers myosin actin ratio was unchanged. The latter findings indicate a
disproportionate loss of myosin with respect to fiber CSA and a proportional loss of myosin
and actin, suggesting a decrease in myofibrillar density within the fibers. MHC isoform
distribution showed a shift in the direction MHC-1 MHC-2A MHC-2X as expected
mainly on the basis of previous findings in rat models of disuse. The proteomic analysis
identified several differentially expressed proteins post-BR, which mainly belonged to
antioxidant defense systems and energy metabolism. The antioxidant defense systems were
down-regulated suggesting that oxidative stress could occur in disused human muscle as
previously showed in rat models. Both an oxidative and four glycolytic enzymes were
down-regulated post-BR suggesting a general downsizing of energy metabolism
RealTimePCR investigations of MyHCs and myogenic factors in muscle remodeling induced by electrostimulation in young and elderly subjects.
Sarcopenia is a condition characterized by loss of mass and strength of skeletal muscle. Among the treatments capable to activate the plasticity of muscular tissue and contrast sarcopenia, there is the neuromuscular electrical stimulation (NMES). Only few studies have analyzed the effects of NMES on the functionality of muscle in elderly subjects in vivo; furthermore, no data are available regarding changes induced by NMES in single fibres dissociated from aged, sarcopenic muscle. Studying the effects and the mechanisms which are activated by NEMS will furnish indications in using these treatments in sarcopenic subjects, especially in the elderly not capable of voluntary exercise. The analysis of NEMS treatments could offer significant advantages in understanding if these protocols alone, or associated with voluntary training, might delay the sarcopenia in elderly people (D'Antona et al., 2003; Mafiuletti et al.,2006). The efficacy of the NMES protocol will be evaluated through the expression analysis of different MyHCs and of myogenic regulation factors that regulate muscle regeneration, studied at genomic level
Measuring muon tracks in Baikal-GVD using a fast reconstruction algorithm
The Baikal Gigaton Volume Detector (Baikal-GVD) is a km-scale neutrino
detector currently under construction in Lake Baikal, Russia. The detector
consists of several thousand optical sensors arranged on vertical strings, with
36 sensors per string. The strings are grouped into clusters of 8 strings each.
Each cluster can operate as a stand-alone neutrino detector. The detector
layout is optimized for the measurement of astrophysical neutrinos with
energies of 100 TeV and above. Events resulting from charged current
interactions of muon (anti-)neutrinos will have a track-like topology in
Baikal-GVD. A fast -based reconstruction algorithm has been developed
to reconstruct such track-like events. The algorithm has been applied to data
collected in 2019 from the first five operational clusters of Baikal-GVD,
resulting in observations of both downgoing atmospheric muons and upgoing
atmospheric neutrinos. This serves as an important milestone towards
experimental validation of the Baikal-GVD design. The analysis is limited to
single-cluster data, favoring nearly-vertical tracks.Comment: 15 pages, 6 figures, 1 table, to be published in Eur. Phys. J.