Résumé: We examined the blood cell profiles of the Iberian pond turtle, also known as the Mediterranean pond turtle (Mauremys leprosa) in two habitats in northeastern Algeria with markedly contrasting water quality. Blood smears were prepared from 38 adult turtles collected at a polluted reference site (Bouhamra) and an unpolluted site (Brabtia). Differential leukocyte counts and erythrocyte morphometrics (length, width, and surface area) were quantified. At Brabtia Reserve, heterophils were the most abundant leukocyte type (41.35%), followed by lymphocytes (27.54%) and monocytes (10.16%). At the Bouhamra site, heterophils are also dominant (57.86%), followed by monocytes (21.40%) and lymphocytes (12.80%). The average ratio of heterophils to lymphocytes (H/L) was 4.39 in the polluted site, Bouhamra, which is about three times higher than the ratio of 1.60 in the pristine, indicating elevated physiological stress. Erythrocyte dimensions differed significantly between sites. In turtles from Brabtia, mean erythrocyte length, width, and surface were 24.10 µm, 13.68 µm, and 260.97 µm², respectively. Corresponding values in turtles from the degraded habitat (Bouhamra) were larger (25.07 µm, 13.96 µm, and 274.95 µm²). Nuclear length, nuclear width, nuclear surface, and nuclear shape index (NL/NW) did not vary between habitats. Our results show that contamination mainly affects the size of red blood cells, while the morphological parameters of the nucleus remain stable. The higher H/L ratio at the polluted site (Bouhamra) also supports the use of leukocyte profiles as solid indicators of chronic environmental stress in freshwater turtles.

Résumé: In this paper we propose an iterative parallel decision feedback (P-DF) receivers associated with parallel interference cancellation (PIC) for multicarrier code division multiple access (MC-CDMA) systems in a Rayleigh fading channel (cost 207). First the most widely detection techniques, minimum mean-squared error MMSE, Maximum Likelihood ML and PIC were investigated in order to compare their performances in terms of Bit Error Rate (BER) with parallel feedback detection P-DFD. A MMSE DF detector that employs parallel decision-feedback (MMSE-P-DFD) is considered and shows almost the same BER performance with MMSE and ML, which present a better result than the other techniques. In a second time, an iterative proposed method based on the multi-stage techniques P-DFD (parallel DFD with two stages) and PIC was exploited to improve the performance of the system.

Résumé: An OFDM system is combined with multiple-input multiple-output (MIMO) in order to increase the diversity gain and system capacity over the time variant frequency-selective channels. However, a major drawback of MIMO-OFDM system is that the transmitted signals on different antennas might exhibit high peak-to-average power ratio (PAPR). In this paper, we present a PAPR analysis reduction of space-timeblock-coded (STBC) MIMO-OFDM system for 4G wirelessnetworks. Several techniques have been used to reduce the PAPR of the (STBC) MIMOOFDM system: clipping and filtering, partial transmit sequence (PTS) and selected mapping (SLM). Simulation results show that clipping and filtering provides a better PAPR reduction than the others methods and only SLM technique conserve the PAPR reduction in reception part of signal