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An integrated trend assessment was conducted for the Gulf of Gdańsk (GoG), Baltic Sea for the period 1994-2010 to describe changes and potentially important drivers of the ecosystem. We found changes in the biota, including an increase in open sea taxa (flatfish, sprat and cod), a decrease in typical coastal species such as eelpout and lumpfish and an increase in primary production. The analyses further suggest that changes in the food web were driven by a combination of anthropogenic pressures (e.g., nutrient loadings and fisheries) and possible interactions with climatic disturbance. Our analyses show that significant changes occurred in the GoG ecosystem between 1994 and 2010. The primary drivers and mechanisms of these changes are discussed. We describe this alteration of the GoG within the context of similar temporal patterns identified in adjacent areas. [ABSTRACT FROM AUTHOR]

On the basis of the Solar Maximum Mission observations, Švestka ( Solar Phys. 121, 399, ) introduced a new class of flares, the so-called flare hybrids. When they start, they look like typical compact flares (phase 1), but later on, they look like flares with arcades of magnetic loops (phase 2). We summarize the characteristic features of flare hybrids in soft and hard X-rays as well as in the extreme ultraviolet; these features allow us to distinguish flare hybrids from other flares. In this article, additional energy release or long plasma cooling timescales are suggested as possible causes of phase 2. We estimate the frequency of flare hybrids, and study the magnetic configurations favorable for flare hybrid occurrence. Flare hybrids appear to be quite frequent, and the difference between the lengths of magnetic loops in the two interacting loop systems seem to be a crucial parameter for determining their characteristics. [ABSTRACT FROM AUTHOR]

The aim of this paper is to test the model of oscillating magnetic traps (the OMT model), proposed by Jakimiec and Tomczak ( Solar Phys. 261, 233, 2010). This model describes the process of excitation of quasi-periodic pulsations (QPPs) observed during solar flares. In the OMT model energetic electrons are accelerated within a triangular, cusp-like structure situated between the reconnection point and the top of a flare loop as seen in soft X-rays. We analyzed QPPs in hard X-ray light curves for 23 flares as observed by Yohkoh. Three independent methods were used. We also used hard X-ray images to localize magnetic traps and soft X-ray images to diagnose thermal plasmas inside the traps. We found that the majority of the observed pulsation periods correlates with the diameters of oscillating magnetic traps, as was predicted by the OMT model. We also found that the electron number density of plasma inside the magnetic traps in the time of pulsation disappearance is strongly connected with the pulsation period. We conclude that the observations are consistent with the predictions of the OMT model for the analyzed set of flares. [ABSTRACT FROM AUTHOR]

We investigated the quasi-periodic oscillations of the hard X-ray (HXR) emission of the large flare of 2 November 1991 using HXR light curves and soft X-ray and HXR images recorded with the Yohkoh X-ray telescopes. We analysed these observations and report five main results: i) The observations confirm that electrons are accelerated in oscillating magnetic traps that are contained within the cusp magnetic structure. ii) The chromospheric upflow increases the density within the magnetic traps, which in turn together with the higher amplitude of the trap oscillations increases the amplitude of the HXR pulses. iii) This increase stops when the density inside the traps increases progressively and inhibits the acceleration of electrons. iv) The model of oscillating magnetic traps is able to explain the time variation of the electron precipitation, the strong asymmetry in the precipitation of the accelerated electrons, and the systematic differences in the precipitation of 15 and 25 keV electrons. v) We have obtained direct observational evidence that strong HXR pulses are the result of the inflow into the accelerated volume of dense plasma from chromospheric evaporation. [ABSTRACT FROM AUTHOR]

In our recent paper (Jakimiec and Tomczak, Solar Physics 261, 233, ) we investigated quasi-periodic oscillations of hard X-rays during the impulsive phase of solar flares. We have come to the conclusion that they are caused by magnetosonic oscillations of magnetic traps within the volume of hard-X-ray (HXR) loop-top sources. In the present paper we investigate four flares that show clear quasi-periodic sequences of the HXR pulses. We also describe our phenomenological model of oscillating magnetic traps to show that it can explain the observed properties of the HXR oscillations. The main results are the following: i) Low-amplitude quasi-periodic oscillations occur before the impulsive phase of some flares. ii) The quasi-periodicity of the oscillations can change in some flares. We interpret this as being due to changes of the length of oscillating magnetic traps. iii) During the impulsive phase a significant part of the energy of accelerated (non-thermal) electrons is deposited within a HXR loop-top source. iv) The quick development of the impulsive phase is due to feedback between the pressure pulses by accelerated electrons and the amplitude of the magnetic-trap oscillation. v) The electron number density and magnetic field strength values obtained for the HXR loop-top sources in several flares fall within the limits of N≈(2 - 15)×10 cm, B≈(45 - 130) gauss. These results show that the HXR quasi-periodic oscillations contain important information about the energy release in solar flares. [ABSTRACT FROM AUTHOR]

The aim of the present paper is to use quasi-periodic oscillations in hard X-rays (HXRs) of solar flares as a diagnostic tool for the investigation of impulsive electron acceleration. We have selected a number of flares which showed quasi-periodic oscillations in hard X-rays and their loop-top sources could be easily recognized in HXR images. We have considered MHD standing waves to explain the observed HXR oscillations. We interpret these HXR oscillations as being due to oscillations of magnetic traps within cusp-like magnetic structures. This is confirmed by the good correlation between periods of the oscillations and the sizes of the loop-top sources. We argue that a model of oscillating magnetic traps is adequate to explain the observations. During the compressions of a trap, particles are accelerated, but during its expansions plasma, coming from chromospheric evaporation, fills the trap, which explains the large number of electrons being accelerated during a sequence of strong pulses. The advantage of our model of oscillating magnetic traps is that it can explain both the pulses of electron acceleration and quasi-periodicity of their distribution in time. [ABSTRACT FROM AUTHOR]

A detailed high resolution survey of a small region (68 × 68 km) of the Subtropical Front south of Australia over a period of 14 days is used to study the interaction between the mixed layer and the permanent frontal structure underneath during summer conditions. The front extends through the mixed layer as a salinity front, while its temperature structure is modified by seasonal warming. Wind-driven movement of the mixed layer combines with the short-time development of indentations and filaments in the front to produce some degree of decoupling between the mixed layer and the underlying structure, and the front is not always found at the same location in and below the mixed layer. Intrusions and parcels of distinct water properties are found just below the mixed layer, produced as a result of the relative movement of the front in and below the mixed layer. These parcels are typically 10 km in width and 10-50 m in depth. Successive surveys of the front with a time separation of 2 days showed that these features persist over at least 1 week. Large scale surveys of the front show that parcels are ubiquitous along the Subtropical Front over a distance of several hundred kilometres. The results suggest that any study aimed at understanding the intricate interaction between the mixed layer and the layers below in oceanic fronts will have to address wind-driven dynamics and frontal dynamics together. [ABSTRACT FROM AUTHOR]

Fusarium head blight (scab) epidemics of wheat occurred in Żuławy (Northern Poland) during 1998 and in Wielkopolska (West) and in Southern regions of Poland in 1999. Four species were identified in wheat heads with scab symptoms: Fusarium culmorum, Fusarium graminearum, Fusarium avenaceum and Microdochium nivale. A significant increase in the frequency of F. graminearum (between 23% and 38%), was observed, compared to about 10% during the previous decade. The mycotoxins deoxynivalenol (DON), nivalenol (NIV) and moniliformin (MON) in amounts up to 24.3, 14.2 and 1.72mgkg−1respectively, were identified in kernels samples. [ABSTRACT FROM AUTHOR]

Inoculation experiments with 12 genotypes of oats (9 lines: CHD 894, CHD 1095, CHD 1296, CHD 1607, CHD 1653, CHD 1692, STH 2293, STH 2393, STH 2494, STH 2694 and 2 cultivars: Farys, Slawko) were performed during the vegetation seasons of 1999 — 2000 in Zamosc region in the South — Eastern part of Poland. Panicles of oats were inoculated with a conidial suspension of Fusarium avenaceum, which caused the following average reductions of traits: yield by 37.8 % and weight of 1000 kernels by 40.2 % respectively. The highest susceptibility to scab development caused by the F. avenaceum inoculation was found particularly for two lines (CHD 894, and CHD 1296) while cultivar Farys and line CHD 1607 exhibited the highest resistance to the disease in terms of TKW and yield reductions after inoculation. During 2 consecutive years (1999 and 2000 respectively) the average level of moniliformin accumulation (mg/kg) in positive samples was respectively 0.51 and 0.12 the highest being 1.11 and 0.26, while the lowest was 0.30 and 0.01. [ABSTRACT FROM AUTHOR]

Presents a study on a barrier layer found in the southern region of the South China Sea based on CTD data gathered during six cruises between 1989 and 1999. Data and methods; Results; Characteristics of the barrier layer.

Activity concentration of 90 Sr and stable strontium concentration was analysed in 42 samples of animal (deer, roe-deer, elk and boar) bones, which mostly originated from north-eastern Poland. Strontium separation was performed by extraction chromatography. Determination of chemical yield was controlled by means of stable Sr determination using atomic spectrometry at the beginning and at the end of the separation procedure. Equilibrated 90 Sr and 90 Y activity was measured using a liquid scintillator spectrometer. Stable strontium range was from 55.4±1.7 ppm to 91.8±4.5 ppm, the mean was 71.84 ppm with a standard deviation (SD) of 9.31 ppm. The mean recovery of strontium was 26.7% with SD = 16.1%. The maximum activity of 90 Sr, equal to 629±13 Bq/kg (ash) was found for a deer sample from Augustów Primeval Forest. In average, deer show the highest radiostrontium level, followed by roe-deer, elk and the lowest level were observed for boar. Differences between boar and deer or roe-deer are significant in terms of Kruskal-Wallis statistical test. Animal bones from north-eastern Poland showed about twice the mean concentration of 90 Sr, compared to those of south-central Poland, but the difference was found not significant. Activities observed in roe-deer bones suggest the deposition of a concentration of 1.9 to 3.5 kBq/m2 in the average of Chernobyl-origin 90 Sr in 1986 in north-eastern Poland. [ABSTRACT FROM AUTHOR]

The intensity ratio of the components of the Mg xii 8.42 Å (1 s S − 2 p P) doublet in solar flare spectra has been investigated using observations recorded from the Intercosmos 7 satellite. The observed values of the ratio fall within the interval 0.38-0.66 and have been compared with recent theoretical predictions based on an optically thin collisional-radiative model. It has been found that for the flare plasma the low values of the ratio cannot be explained since they fall below the smallest theoretical value. The highest values on the other hand require that an unacceptably high electron density be postulated. It is suggested that both high and low values may be caused by the resonance line scattering of the Mg xii quanta in the flare volume, provided that the volume is elongated and not spherical. The intensity of the nearby satellite lines is also investigated. Good agreement between the theoretical and observed intensities is found. [ABSTRACT FROM AUTHOR]