Timing synchronization for cooperative wireless communications

In this work the effect of perfect and imperfect synchronization on the performance of single-link and cooperative communication is investigated. A feedforward non- data-aided near maximum likelihood (NDA-NML) timing estimator which is effective for an additive white Gaussian noise (AWGN) channel and also for a flat-fading channel, is developed. The Cramer Rao bound (CRB) and modified Cramer Rao bound (MCRB) for the estimator for a single-link transmission over an AWGN channel is derived. A closed form expression for the probability distribution of the timing estimator is also derived. The bit-error-rate (BER) degradation of the NDA-NML timing estimator with raised cosine pulse shaping for static timing errors over an AWGN channel is characterized. A closed form expression is derived for the conditional bit error probability (BEP) with static timing errors of binary phase shift keying modulation over a Rayleigh fading channel using rectangular pulse shaping. The NDA-NML timing estimator is applied to a cooperative communication system with a source, a relay and a destination. A CRB for the estimator for asymptotically low signal-to-noise-ratio case is derived. The timing complexity of the NDA-NML estimator is derived and compared with a feedforward correlation based data-aided maximum likelihood (DA-ML) estimator. The BER performance of this system operating with a detect-and-forward relaying is studied, where the symbol timings are estimated independently for each channel. A feedforward data and channel aided maximum likelihood (DCA-ML) symbol timing estimator for cooperative communication operating over flat fading channels is then developed. For more severe fading the DCA-ML estimator performs better than the NDA- NML estimator and the DA-ML estimator. The performance gains of the DCA-ML estimator over that of the DA-ML estimator become more significant in cooperative transmission than in single-link node-to-node transmission. The NDA-NML symbol timing estimator is applied to three-node cooperative communication in fast flat-fading conditions with various signal constellations. It is found that timing errors have significant effect on performance in fast flat-fading channels. The lower complexity NDA-NML estimator performs well for larger signal constellations in fast fading, when compared to DA-ML estimator. The application of cooperative techniques for saving transmit power is discussed along with the related performance analysis with timing synchronization errors. It is found that power allocations at the source and relay nodes for transmissions, and the related timing errors at the relay and the destination nodes, have considerable effect on the BER performance for power constrained cooperative communication. The performance of multi-node multi-relay decode-and-forward cooperative com- munication system, of various architectures, operating under different fading con- ditions, with timing synchronization and various combining methods, is presented. Switch-and-stay combining and switch-and-examine combining are proposed for multi-node cooperative communication. Apart from the proposed two combining methods equal gain combining, maximal ratio combining and selection combining are also used. It is demonstrated that synchronization error has significant effect on performance in cooperative communication with a range of system architectures, and it is also demonstrated that performance degradation due to synchronization error increases with increasing diversity. It is demonstrated that decode-and- forward relaying strategy with timing synchronization, using a very simple coding scheme, performs better than detect-and-forward relaying with timing synchronization. Analytical expressions are derived for BEP with static and dynamic timing synchronization errors over Rayleigh fading channels using rectangular pulse shaping for amplify-and-forward and detect-and-forward cooperative communications. Moment generating function (MGF) based approach is utilized to find the analytical expressions. It is found that timing synchronization errors have an antagonistic effect on the BEP performance of cooperative communication. With the relay intelligence of knowing whether symbols are detected correctly or not, detect- and-forward cooperative communication performs better than the low complexity amplify-and-forward cooperative communication

Assessment of soil and water quality as affected by herbicide application in the rice field of Bangladesh

Weed is a vital constraint for crop especially rice cultivation. Among several techniques herbicidal weed control is thought to be efficient and cost effective method. But herbicide may change soil or water quality in rice field. Taking this into consideration a study was conducted to assess soil and water quality in herbicide applied rice field. The study was conducted in two phases. In first phase a list of herbicide was made according to the uses by the local farmers of Mymensingh district. It was found that among the herbicides wide used two herbicides were i. Laser (Pyrazosulphuron ethyl-10 WP) and ii. Changer (Acetachlor-14% + Bensulfuron methyl-4%). In the second phase, an experiment was conducted at Agronomy Field Laboratory, Bangladesh Agricultural University, Mymensingh considering these two herbicides. It was found that the application of herbicide in the rice field did not change the nutrient content in the soil or water of rice field. But herbicide significantly reduced the microbial activity and increased the chlorine content (In case of herbicide 2 i.e. Acetachlor-14% + Bensulfuron methyl-4%) in both soil and water of rice field. Therefore, it can be concluded that though the nutrient content of the soil of rice field is not significantly affected by herbicide application but the presence of high amount of Cl content in the rice field may cause burning injury of rice leaf at the early stages of its growth which could affect the yield of rice

Turbinoplasty by laser

This is a study of 61 cases of turbinoplasty done in 3 hospitals of Bangladesh from August’ 2007 to July’ 2009 (2 years). This study compares turbinoplasty by laser with that of non-laser techniques. 60.65 % of patients were operated by laser and 39.34 % of patients were operated by non-laser techniques. Majority of the patients were from 21- 40 years of age, (62.16% in laser group and 54.16% in non-laser group). Male & Female patients ratio was 3:1 in both groups. 100 % of the patients were presented with nasal obstruction. 98.36% with nasal discharge, 95.08% with headache and 75.40 % with frequent sneezing (p<0.01). Most patients were operated under local anesthesia in both groups (78.38 % and 58.33 % respectably). Follow up was satisfactory up to 3 months (Laser group 81.08 % and non-laser group 70.83%). Most of the patient were all symptoms free (86.48 % in laser group and 79.16 % in nonlaser group). Only 8 patients (21.62 %) present with crusting in laser group in respect to 22 patients (91.66%) in non-laser group with no incidence of severe post–operative nasal bleeding in laser group. 34 patients (91.89 %) of Laser group and 13 patients (35.13 %) of non-laser group were treated as day care surgery.Most of the cases (70.27 %) were operated by diode laser. Recurrences of symptoms were negligible in laser group (2.70%)

Glycemic Index Values of Rice Varieties that are Commonly Available in Markets in Bangladesh

Glycemic Index (GI) of six common rice varieties in the local markets of Bangladesh was assessed and categorized in this study to investigate manipulative varietal performance for the time being. After overnight fasting, each of ten selected healthy non-diabetic volunteers (males and females in ratio of 1:1) was fed with reference food (50 g glucose) and test foods (50 g carbohydrate-containing different rice varieties) in every two days intervals. After feeding, glucose levels (mmol/l) were measured at 0, 15, 30, 45, 60, 90 and 120 minutes. Incremental Area Under Curve (IAUC) of reference food and test food (avoiding the area beneath the baseline of reference food) was calculated to measure GI values. Amylose content (%) of different test foods was measured from the standard curve obtained from the spectrophotometric analysis after alcoholic-alkaline gelatinization that was followed by acidification and iodine mixing. The result showed that the GI values were 59.7±3.4; 50.5±2.6; 57.8±2.8; 51.3±2.3; 56.9±3.9 and 44.6±2.1, while the amylose content (%) were 23.6±0.6; 26.7±0.9; 21.3±0.7; 28.3±1.1; 22.2±2.3 and 29.8±1.5 for Nizershail, BRRI Dhan 29, Chinigura, Kalijira, Hybrid Hera Dhan 12 and Sworna, respectively. Moreover, the existing inverse relationship between the GI values and amylose content in this study was similar to other researchers’ findings. Categorization of the test foods based on the observed GI values ranked Sworna, BRRI Dhan 29 and Kalijira as low GI rice varieties that could be beneficial for consumption by diabetics as well as healthy individuals

Anaesthetic complications in CO2 laser in ENT surgery

The word laser is an acronym for light amplificationby stimulated emission of radiation and lasertechnology is one consequence of Novel Prize winningin quantum mechanics, which is most important in20th century physical sciences. The rapidadvancement of this technology in ENT surgery hasbeen accompanied by complications, making itimperative that anaesthesiologists as well as ENTsurgeons understand the potential threat to theirpatients and themselves and be preparing to respondproperly. CO2 Laser surgery in ENT is one of thosesurgical procedures in which the surgical risk isminimal while the anaesthetic risk is great. This isbecause of the general problems presented bylaryngeal, pharyngeal and tracheal surgeries combinedwith unique specific problems of the lase

CO2 laser tonsillectomy: a comparison with conventional technique

Objective: To define the advantages and disadvantages of CO2 laser tonsillectomy compared with conventional method. Study design: Retrospective review. Setting: Department of Otolaryngology & Head and Neck Surgery, Apollo Hospitals Dhaka. Materials and Methods: This study included fifty two patients with tonsillectomies from October 2007 to May 2008. The patients were diagnosed with history and clinical examination. Preoperative investigations have been done for general anaesthesia. Patients were intubated with laser reinforced endotracheal tube and fire precautions were taken. Laser tonsillectomy has been avoided below 10 years in our centre. 52 patients aged 10-35 years underwent tonsillectomy in a period of 10 months. Out of them 12 patients underwent laser tonsillectomies. The data of each patient included intra-operative blood loss, operation time, postoperative pain and postoperative healing. Results: All Patients were admitted for 24 hours. Intra operative blood loss was dramatically less with the use of CO2 laser than that of conventional method (5ml vs. 18ml). Profuse bleeding did not prolong this time especially in laser technique. The incidence of postoperative reactionary hemorrhage were not significantly different between two techniques. 2 patients suffered with secondary haemorrhage in conventional technique and in laser technique one patient had secondary haemorrhage. There was statistically significant difference in duration of operating time (15 vs. 40 min). Both methods of surgery had non-identical effect on post operative pain. Postoperative pain was less in laser technique than that of conventional technique in 7 days postoperative follow up. Leukocytic membrane formation and separation and final healing were earlier in laser technique than in conventional technique. Conclusion: CO2 laser is a safe and acceptable method for tonsillectomy. CO2 laser tonsillectomy reduces operation time and intraoperative blood loss. Postoperative pain is less than conventional technique and healing is also earlier in laser technique

The first complete mitogenome of Indian star tortoise (Geochelone elegans)

The complete mitochondrial genome of Indian star tortoise (Geochelone elegans) was characterized having 16,446 bp nucleotides encoding 37 genes in circular orientation comprising 13 protein-coding genes, 22 tRNA genes and two rRNA genes. The lengths of 12S and 16S ribosomal RNA were 973 bp and 1600 bp. A non-coding control region (D-Loop) of 966 bp was identified between tRNAPro and tRNAPhe having seven interrupted tandem repeats. A single A + 1 frameshift insertion in the ND3 gene (ND3-174) was also discovered. The complete mitogenome of G. elegans would contribute in deeper understanding of the evolutionary dynamics and conservation effort of vulnerable testudine families

Coordination chemistry and bioactivity of Ni2+, Cu2+, Cd2+ and Zn2+ complexes containing bidentate schiff bases derived from S-benzyldithiocarbazate and the X-ray crystal structure of bis[S-benzyl-β-N-(5-methyl-2-furylmethylene)dithiocarbazato]cadmium(II).

New bidentate isomeric NS and NS′ Schiff bases were derived from the condensation of S-benzyldithiocarbazate (SBDTC) with 5-methyl-2-furyldehyde and 2-furyl-methylketone. Reaction of NS ligand with Ni(II), Cu(II), Cd(II) and Zn(II) salts gave solid complexes. Only the Ni(II) complex of the NS′ ligand was isolated. All complexes were characterized by a variety of physico-chemical techniques, viz. elemental analyses, molar conductivity, i.r. and electronic spectral studies. The Schiff bases behaved as uninegatively charged bidentate ligands. Square-planar structures have been proposed for the Cu(II) complex containing the NS Schiff base ligand and the Ni(II) complexes of the bidentate NS and NS′ Schiff base ligands. Single crystal X-ray diffraction study of [Cd(NS)2] showed that the complex was bis chelated with a distorted tetrahedral structure. The antimicrobial properties of the Schiff bases and their metal complexes indicate that the organic compounds are stronger antifungal agents than their complexes with the metals studied. However, the zinc complex of the Schiff base, S-benzyl-β-N-(5-methyl-2-furyl)methylenedithiocarbazate, (NS), was found to be highly active against CEM-SS (Human cell T-lymphoblastic leukemia) with a CD50 value of 2.0 μg cm−3, while [Cd(NS)2] was moderately active with a CD50 value of 4.95 μg cm−3. None of the compounds were found to be active against HT-29 (Human colon adenocarcinoma cells). The bioactivity of a previously reported tridentate NNS Schiff base (SBD1) and its metal complexes with nickel(II) and copper(II) are also discussed