Wyniki wyszukiwania - Biblioteka Nauki

Nowa wersja platformy, zawierająca wyłącznie zasoby pełnotekstowe, jest już dostępna.
Przejdź na https://bibliotekanauki.pl

Ograniczanie wyników

Znaleziono wyników: 4

Liczba wyników na stronie

Wyniki wyszukiwania

Sortuj według:

Ogranicz wyniki do:

Diver Observations by Means of Acoustic Methods

100%

Kozaczka E. , Grelowska G. , Kozaczka S. , Szymczak W.

Acta Physica Polonica A

2013

tom 123

nr 6

1098-1100

Searching for objects, especially small ones, moving under water near its the free surface, is always not an easy task. Designing tools for the detection of such targets is a real challenge when the possibility of a terrorist attack is a real threat. This paper presents some aspects of diver detection by means of acoustics methods, both active (side scan sonar) and passive ones (linear receiving antenna). This approach is quite effective because divers can use both breathing apparatus operating in the closed-loop (so-called rebreathers), and popular open-circuit breathing (exhalation of used air or a breathing gas mixture into the water).

Hyposensitivity to amphetamine following exposure to chlorphenvinphos - protection by amphetamine preexposure

100%

Gralewicz S. , Lutz P. , Szymczak W.

Acta Neurobiologiae Experimentalis

2000

tom 60

nr 2

203-207

We investigated the effect of an acute exposure to chlorphenvinphos (CVP), an organophosphate anticholinesterase, on amphetamine-induced open-field locomotion in rats. CVP was administered in a single i.p. dose of 1.0 mg/kg (1/10 of the LD50). All animals were challenged with 1.0 mg/kg amphetamine (AMPH) three weeks after the CVP exposure, i.e. after a time sufficient for acetylcholinesterase recovery. Some rats were also given AMPH three weeks before the CVP exposure. In rats challenged with AMPH only once after the CVP exposure, AMPH- induced open-field locomotion was significantly reduced. Such an effect was not observed in rats given AMPH three weeks before the CVP exposure. The results suggest that a single CVP exposure may result in persistent dopaminergic hyposensitivity, and that an amphetamine pretreatment may protect the rat against this effect.

The Examination of the Upper Layers of the Seabed by the Means of the Acoustic Methods

100%

Kozaczka E. , Grelowska G. , Szymczak W. , Kozaczka S.

Acta Physica Polonica A

2011

tom 119

nr 6A

1091-1094

Propagation of acoustic waves in the sea, in particular in shallow sea, depends on several factors. The basic of them are source power and frequency of acoustic waves, spatial distribution inhomogeneous medium in which acoustic wave propagates, and distributions of speed of sound and density of seawater. The coastal conditions, which limit water medium from above (free surface of the sea) and from bottom (the seabed), are no less important. In this paper we will consider the examination of the layer structure of the seabed by the means of the acoustic methods. By the notion of acoustic methods we mean use of phenomena in the field of nonlinear hydroacoustics. Based on this, the parametric sonar was constructed and was used to the seabed sounding. This parametric sonar is commonly called sub-bottom profiler. The selected results of extensive experimental research, that have been performed in waters of the Gulf of Gdańsk in the years 2008-2010, will be presented in this work.

Investigation of Transmit and Receive Characteristics of Laboratory Model for the Parametric Echosounder

75%

Grelowska G. , Kozaczka E. , Nowicki A. , Kozaczka S. , Szymczak W. , Tymkiewicz R.

Acta Physica Polonica A

2013

tom 123

nr 6

1094-1097

Investigation and operation of devices based on nonlinear interaction of high-intensity waves have been carried out for several decades. However, it is still a new tool to study the properties of the water environment and especially the upper layers of the seabed. This paper describes the results of tests of the new device that is intended to be applied for sounding underwater areas. The device has been designed and built in collaboration with the Department of Ultrasound of the Institute of Fundamental Scientific Researches of the Polish Academy of Sciences in Warsaw.