THE QUALITY OF THE AQUATIC ENVIRONMENT IN FISH PONDS

In our country, the most widespread growth system is the semi-intensive one with growth units represented by ponds (anthropogenic ecosystems). The semi-intensive fish culture is based on the natural productivity and / or enriched by fertilization of the anthropogenic ecosystems, respectively also on the administration of supplementary food. In fact, semi-intensive cultivation involves obtaining a fish biomass with low production costs due to the use of inexpensive inputs. The productionprofile and the way of obtaining it determine the structure and duration oftheexploitation cycle within a fish farm

Evidence for Proportionate Partition Between the Magnetic Field and Hot Gas in Turbulent Cassiopeia A

We present a deep X-ray observation of the young Galactic supernova remnant Cas A, acquired with the ROSAT High Resolution Imager. This high dynamic range (232 ks) image reveals low-surface-brightness X-ray structure, which appears qualitatively similar to corresponding radio features. We consider the correlation between the X-ray and radio morphologies and its physical implications. After correcting for the inhomogeneous absorption across the remnant, we performed a point by point (4" resolution) surface brightness comparison between the X-ray and radio images. We find a strong (r = 0.75) log-log correlation, implying an overall relationship of $\log(\Sigma_{_{\rm X-ray}}) \propto (2.21\pm0.05) \times \log(\Sigma_{_{\rm radio}})$. This is consistent with proportionate partition (and possibly equipartition) between the local magnetic field and the hot gas --- implying that Cas A's plasma is fully turbulent and continuously amplifying the magnetic field.Comment: 8 pages with embedded bitmapped figures, Accepted by ApJ Letters 5/1/9

XMM-Newton discovery of transient X-ray pulsar in NGC 1313

We report on the discovery and analysis of the transient X-ray pulsar XMMU J031747.5-663010 detected in the 2004 November 23 XMM-Newton observation of the spiral galaxy NGC 1313. The X-ray source exhibits pulsations with a period P~765.6 s and a nearly sinusoidal pulse shape and pulsed fraction ~38% in the 0.3-7 keV energy range. The X-ray spectrum of XMMU J031747.5-663010 is hard and is well fitted with an absorbed simple power law of photon index ~1.5 in the 0.3-7 keV energy band. The X-ray properties of the source and the absence of an optical/UV counterpart brighter than 20 mag allow us to identify XMMU J031747.5-663010 as an accreting X-ray pulsar located in NGC 1313. The estimated absorbed 0.3-7 keV luminosity of the source L~1.6\times 10^{39} ergs/s, makes it one of the brightest X-ray pulsars known. Based on the relatively long pulse period and transient behaviour of the source, we classify it as a Be binary X-ray pulsar candidate. XMMU J031747.5-663010 is the second X-ray pulsar detected outside the Local Group, after transient 18 s pulsating source CXOU J073709.1+653544 discovered in the nearby spiral galaxy NGC 2403.Comment: 6 pages, 4 figures. Accepted for publication in MNRAS. Updated to match the accepted versio

A Chandra Observation of the Diffuse Emission in the Face-on Spiral NGC 6946

This paper describes the {\it Chandra} observation of the diffuse emission in the face-on spiral NGC 6946. Overlaid on optical and H${\alpha}$ images, the diffuse emission follows the spiral structure of the galaxy. An overlay on a 6 cm polarized radio intensity map confirms the phase offset of the polarized emission. We then extract and fit the spectrum of the unresolved emission with several spectral models. All model fits show a consistent continuum thermal temperature with a mean value of 0.25$\pm$0.03 keV. Additional degrees of freedom are required to obtain a good fit and any of several models satisfy that need; one model uses a second continuum component with a temperature of 0.70$\pm$0.10 keV. An abundance measure of 3$^{+1.95}_{-1.90}$ for Si differs from the solar value at the 90% confidence level; the net diffuse spectrum shows the line lies above the instrumental Si feature. For Fe, the abundance measure of 0.67$\pm$0.13 is significant at 99%. Multiple gaussians also provide a good fit. Two of the fitted gaussians capture the O VII and O VIII emission; the fitted emission is consistent with an {\it XMM-Newton} RGS spectrum of diffuse gas in M81. The ratio of the two lines is $<$0.6-0.7 and suggests the possibility of non-equilibrium ionization conditions exist in the ISM of NGC 6946. An extrapolation of the point source luminosity distribution shows the diffuse component is not the sum of unresolved point sources; their contribution is at most 25%.Comment: accepted for ApJ; 16 pages; 12 figs; to meet Archive size limits, most converted to jpe

Regulatory components involved in cold tolerance of barley cells

Micro- and macroclimatic changes fundamentally determine growth rate, development, crop production and geographical distribution of plant species. The existence of successful defensive mechanisms against the damaging effects of low temperature is essential for survival and sufficient seed production of plants. In winter-type cereals cold acclimation process is activated by low temperature, and it leads to elevated level of resistance against harmful physiological effects of suboptimal temperature. One of the most important gene expression regulator units in this mechanism is the CBF-COR system. However, cold acclimation mechanism is a very complex phenomenon, the process is influenced by many factors, e.g. falling temperature, day length, spectral composition of irradiated light, as well as local and systemic internal signals. Because of this, realignment of the gene expression pattern connected to the cold acclimation mechanism and its phenotypical effects is very difficult to investigate excluding the influence of other factors with interfering action. Basic cellular and biochemical changes caused by only the low temperature, independently of another factors mentioned above are mainly undiscovered. Therefore, elemental cold response of the CBF-COR system was compared in seedlings and dark-grown, dedifferentiated, meristemoid callus cultures of winter barley. Detailed characteristics of CBF-COR induction and effects of cold-hardening were also studied in barley callus cultures at the gene expression, hormone composition and freezing tolerance levels in the presence or absence of Dicamba, the exogenous auxin analogue used in tissue cultivation. Our results suggest the presence of a basal, cold-responsive activation mechanism of CBF and COR genes with the highest influence on the evolvement of frost resistance, which is independent of the differentiated state of cells or chloroplast-related, light-induced and systemic signals. However, these factors seem to be required for reaching the maximum level of activation. The exogenous auxin analogue, Dicamba, seems to be rather a coinducer in this process, since it does not affect the initiation or the characteristic of the activation, only influences the magnitude of the response

IMPACT OF GRANULAR FLOW DYNAMICS ON THE DESIGN AND MODELLING OF THE BUNKERS

Silos and bunkers are widely used in the storage, storage and distribution of granular materials, of particular importance in the management of handling, transport and conditioning operations. The distribution of seeds at the filling and emptying stage of the bunker examines the main loading and unloading hypotheses leading to different limit states for its structure. This paper will present the results of causes such as the maximum pressure perpendicular to the vertical wall of the silo, the maximum stretching effort due to friction with the vertical wall, the vertical pressure on the basis of it and the maximum load on the bunker funnel, resulting in the implementation of new design and modeling solutions. At the same time, the dynamics of the granular flow in the bunkers, including flow regimes, design and optimal shapes, will be described to avoid the loss of energy generated by the collision of macroscopic particles inside it

EXPERIMENTAL RESEARCH ON DETERMINATION OF DEFORMATIONS IN THE CUTTING PROCESS IN WET SANDY SOILS

The active parts of tillage equipment must be checked for wear resistance, under different conditions working with the soil, so that the average life span should be determined wear resistance, to ensure timely changes of parts. Research in the field has shown that there are at least two main forces acting on the active parts: impact and friction, the action of these forces causes wear. In order to test the tillage knives in laboratory conditions, was used a stand made by INMA Bucharest. With the help of this stand, the deformations in the cutting process were determined in different working conditions: at a certain working speed and at a certain humidity of the sandy soil

CONSIDERATIONS REGARDING THE IMPORTANCE OF THE SORTING OPERATION OF FRUITS AND VEGETABLES

For the normal development of daily activity and maintaining health, the body needs a certain amount of energy and complete nutritional factors (proteins, carbohydrates, lipids, vitamins, minerals, water). They are obtained from food, fruits and vegetables occupying a prominent place as a natural source of carbohydrates, alkalizing mineral salts, vitamins and water. Conditioning involves a set of operations aimed at bringing the products to the characteristics provided by standards, specific to a certain direction of capitalization. This article describes the operations included in the conditioning process, the role and importance of presorting and sorting fruits and vegetables, as well as equipment for these operations

Searching for the pulsar in G18.95-1.1: Discovery of an X-ray point source and associated synchrotron nebula with Chandra

Using the Chandra X-ray Observatory, we have pinpointed the location of a faint X-ray point source (CXOUJ182913.1-125113) and an associated diffuse nebula in the composite supernova remnant G18.95-1.1. These objects appear to be the long-sought pulsar and its wind nebula. The X-ray spectrum of the point source is best described by an absorbed powerlaw model with Gamma=1.6 and an N_H of ~1x10^(22) cm^(-2). This model predicts a relatively low unabsorbed X-ray luminosity of about L_X (0.5-8.0keV) = 4.1x10^(31)D_2^2 erg s^(-1), where D_2 is the distance in units of 2kpc. The best-fitted model of the diffuse nebula is a combination of thermal (kT = 0.48keV) and non-thermal (1.4 < Gamma < 1.9) emission. The unabsorbed X-ray luminosity of L_X = 5.4x10^(33)D_2^2 erg s^(-1) in the 0.5-8keV energy band seems to be largely dominated by the thermal component from the SNR, providing 87% of L_X in this band. No radio or X-ray pulsations have been reported for CXOUJ182913.1-125113. If we assume an age of ~5300yr for G18.95-1.1 and use the X-ray luminosity for the pulsar and the wind nebula together with the relationship between spin-down luminosity (via magnetic dipole radiation) and period, we estimate the pulsar's period to be P = 0.4s. Compared to other rotation-powered pulsars, a magnetic field of 2.2x10^(13)G is implied by its location in the P-Pdot diagram, a value which is close to that of the quantum critical field.Comment: 8 pages, 3 Figures, accepted for publication in Ap