Monitoring of hydrochemical parameters of the recirculating aquasystem in the early stages of ontogeny of Acipenser Ruthenus

The technological process of reproduction and rearing of Acipenser Ruthenus, juveniles and older age groups, in industrial fish farms is carried out in recirculating aquaculture systems with constant monitoring of the hydrochemical regime of the aquatic environment and strict adherence to the technology of phased feeding with live and artificial feed. Raising sturgeon species in winter at low temperatures (2–6 ºС) is one of the most difficult technological processes. The selection of Acipenser Ruthenus fry was carried out in February 2024 at a water temperature of 4 °C and gradually increased by 0.5 °C per day for 20 days to prevent a sharp increase, which could provoke active mobility and exhaustion, injury, and weight loss. The water temperature in the pools and trays of the experimental farm fluctuated between 4 and 18 °C during February – March 2024, which corresponds to the generally accepted temperature range for reproduction and rearing of Acipenser Ruthenus. Compliance with the temperature regime and control of the dissolved oxygen content in water directly affects the survival, growth rate and feed consumption efficiency of Acipenser Ruthenus juveniles at juvenile stages of development. Water turbidity is the only indicator that does not comply with GOST 3351-74 and ranged from 1.12–1.53 mg/dm3 with a norm of ≤ 1 mg/dm3, which is 0.01–0.02 % higher than the norm and indicates the ingress of a small amount of meltwater and rainwater runoff into groundwater. Exceeding the norm of turbidity can adversely affect the vital activity of aquatic organisms in recirculating aquaculture systems and affect body weight gain because suspended particles settle on the gills of fish and impair their respiration, food consumption and ionic metabolism. The presence of chlorides of organic origin in water indicates its contamination, but in the studied water samples its content ranged from 14.18–16.31 mg/dm3, which does not exceed the norm according to the Sanitary and Epidemiological Standards. The lack of oxygen in water can affect the accumulation of hydrogen sulfide as a result of the reduction of sulfuric salts and, as a result, lead to an increase in the content of sulfates, but in our case, the hydrochemical analysis of the water samples under study shows that the sulfate content does not exceed the norm and is 13–52.6 mg/dm3. To organise a balanced feeding of young Acipenser ruthenus at this industrial farm, Artemia salina is used as live feed. To obtain live fodder, we incubated pre-prepared Artemia salina eggs, which allows us to obtain a complete feed for feeding Acipenser ruthenus juveniles in a short time. The decontamination of Artemia salina eggs was carried out in incubation devices (with mandatory aeration, which ensures the absence of anaerobic zones in the egg mass and intensive lighting. For incubation, a solution of 50 g (5 % w/v) of sodium chloride (NaCI) per 1 litre of water is prepared, into which eggs are loaded at a density of 5 g/L. For one apparatus, load 10 litres of water and 50 g of Artemia salina eggs. The incubation lasts 24 hours at a water temperature of 27–29 °C. The yield of Artemia salina nauplii from one device is about 80 %

The near-infrared size-luminosity relations for Herbig Ae/Be disks

We report the results of a sensitive K-band survey of Herbig Ae/Be disk sizes using the 85-m baseline Keck Interferometer. Targets were chosen to span the maximum range of stellar properties to probe the disk size dependence on luminosity and effective temperature. For most targets, the measured near-infrared sizes (ranging from 0.2 to 4 AU) support a simple disk model possessing a central optically-thin (dust-free) cavity, ringed by hot dust emitting at the expected sublimation temperatures (T_sub~1000-1500K). Furthermore, we find a tight correlation of disk size with source luminosity R propto L^(1/2) for Ae and late Be systems (valid over more than 2 decades in luminosity), confirming earlier suggestions based on lower-quality data. Interestingly, the inferred dust-free inner cavities of the highest luminosity sources (Herbig B0-B3 stars) are under-sized compared to predictions of the optically-thin cavity model, likely due to optically-thick gas within the inner AU.Comment: Accepted by Astrophysical Journal; 24 pages, 4 figures, 4 table

Interferometer Observations of Subparsec-scale Infrared Emission in the Nucleus of NGC 4151

We report novel, high-angular resolution interferometric measurements that imply the near-infrared nuclear emission in NGC 4151 is unexpectedly compact. We have observed the nucleus of NGC 4151 at 2.2 microns using the two 10-meter Keck telescopes as an interferometer and find a marginally resolved source ~0.1 pc in diameter. Our measurements rule out models in which a majority of the K band nuclear emission is produced on scales larger than this size. The interpretation of our measurement most consistent with other observations is that the emission mainly originates directly in the central accretion disk. This implies that AGN unification models invoking hot, optically thick dust may not be applicable to NGC 4151.Comment: 9 pages, 1 figure, accepted for publication in the Astrophysical Journal, Letter

First upper limits from LIGO on gravitational wave bursts

We report on a search for gravitational wave bursts using data from the first science run of the LIGO detectors. Our search focuses on bursts with durations ranging from 4 ms to 100 ms, and with significant power in the LIGO sensitivity band of 150 to 3000 Hz. We bound the rate for such detected bursts at less than 1.6 events per day at 90% confidence level. This result is interpreted in terms of the detection efficiency for ad hoc waveforms (Gaussians and sine-Gaussians) as a function of their root-sum-square strain h_{rss}; typical sensitivities lie in the range h_{rss} ~ 10^{-19} - 10^{-17} strain/rtHz, depending on waveform. We discuss improvements in the search method that will be applied to future science data from LIGO and other gravitational wave detectors.Comment: 21 pages, 15 figures, accepted by Phys Rev D. Fixed a few small typos and updated a few reference

Searching for gravitational waves from known pulsars

We present upper limits on the amplitude of gravitational waves from 28 isolated pulsars using data from the second science run of LIGO. The results are also expressed as a constraint on the pulsars' equatorial ellipticities. We discuss a new way of presenting such ellipticity upper limits that takes account of the uncertainties of the pulsar moment of inertia. We also extend our previous method to search for known pulsars in binary systems, of which there are about 80 in the sensitive frequency range of LIGO and GEO 600.Comment: Accepted by CQG for the proceeding of GWDAW9, 7 pages, 2 figure

Upper limits on the strength of periodic gravitational waves from PSR J1939+2134

The first science run of the LIGO and GEO gravitational wave detectors presented the opportunity to test methods of searching for gravitational waves from known pulsars. Here we present new direct upper limits on the strength of waves from the pulsar PSR J1939+2134 using two independent analysis methods, one in the frequency domain using frequentist statistics and one in the time domain using Bayesian inference. Both methods show that the strain amplitude at Earth from this pulsar is less than a few times $10^{-22}$.Comment: 7 pages, 1 figure, to appear in the Proceedings of the 5th Edoardo Amaldi Conference on Gravitational Waves, Tirrenia, Pisa, Italy, 6-11 July 200

Setting upper limits on the strength of periodic gravitational waves from PSR J1939+2134 using the first science data from the GEO 600 and LIGO detectors

Data collected by the GEO 600 and LIGO interferometric gravitational wave detectors during their first observational science run were searched for continuous gravitational waves from the pulsar J1939+2134 at twice its rotation frequency. Two independent analysis methods were used and are demonstrated in this paper: a frequency domain method and a time domain method. Both achieve consistent null results, placing new upper limits on the strength of the pulsar's gravitational wave emission. A model emission mechanism is used to interpret the limits as a constraint on the pulsar's equatorial ellipticity

Improving the sensitivity to gravitational-wave sources by modifying the input-output optics of advanced interferometers

We study frequency dependent (FD) input-output schemes for signal-recycling interferometers, the baseline design of Advanced LIGO and the current configuration of GEO 600. Complementary to a recent proposal by Harms et al. to use FD input squeezing and ordinary homodyne detection, we explore a scheme which uses ordinary squeezed vacuum, but FD readout. Both schemes, which are sub-optimal among all possible input-output schemes, provide a global noise suppression by the power squeeze factor, while being realizable by using detuned Fabry-Perot cavities as input/output filters. At high frequencies, the two schemes are shown to be equivalent, while at low frequencies our scheme gives better performance than that of Harms et al., and is nearly fully optimal. We then study the sensitivity improvement achievable by these schemes in Advanced LIGO era (with 30-m filter cavities and current estimates of filter-mirror losses and thermal noise), for neutron star binary inspirals, and for narrowband GW sources such as low-mass X-ray binaries and known radio pulsars. Optical losses are shown to be a major obstacle for the actual implementation of these techniques in Advanced LIGO. On time scales of third-generation interferometers, like EURO/LIGO-III (~2012), with kilometer-scale filter cavities, a signal-recycling interferometer with the FD readout scheme explored in this paper can have performances comparable to existing proposals. [abridged]Comment: Figs. 9 and 12 corrected; Appendix added for narrowband data analysi

Analysis of LIGO data for gravitational waves from binary neutron stars

We report on a search for gravitational waves from coalescing compact binary systems in the Milky Way and the Magellanic Clouds. The analysis uses data taken by two of the three LIGO interferometers during the first LIGO science run and illustrates a method of setting upper limits on inspiral event rates using interferometer data. The analysis pipeline is described with particular attention to data selection and coincidence between the two interferometers. We establish an observational upper limit of $\mathcal{R}<$1.7 \times 10^{2}$per year per Milky Way Equivalent Galaxy (MWEG), with 90coalescence rate of binary systems in which each component has a mass in the range 1--3$M_\odot$.Comment: 17 pages, 9 figure