Outage Probability of Multiple-Input Single-Output (MISO) Systems with Delayed Feedback

We investigate the effect of feedback delay on the outage probability of multiple-input single-output (MISO) fading channels. Channel state information at the transmitter (CSIT) is a delayed version of the channel state information available at the receiver (CSIR). We consider two cases of CSIR: (a) perfect CSIR and (b) CSI estimated at the receiver using training symbols. With perfect CSIR, under a short-term power constraint, we determine: (a) the outage probability for beamforming with imperfect CSIT (BF-IC) analytically, and (b) the optimal spatial power allocation (OSPA) scheme that minimizes outage numerically. Results show that, for delayed CSIT, BF-IC is close to optimal for low SNR and uniform spatial power allocation (USPA) is close to optimal at high SNR. Similarly, under a long-term power constraint, we show that BF-IC is close to optimal for low SNR and USPA is close to optimal at high SNR. With imperfect CSIR, we obtain an upper bound on the outage probability with USPA and BF-IC. Results show that the loss in performance due to imperfection in CSIR is not significant, if the training power is chosen appropriately.Comment: Submitted to IEEE Transactions on Communications Jan 2007, Revised Jun 2007, Revised Nov 200

Visual and Surface Properties of CdTe Thin Films on CdS/FTO Glass Substrates

Cadmium telluride (CdTe) thin film material was deposited ontop of Cadmium Sulfide (CdS) substrate using vacuum evaporation technique. The sample was characterized using X-ray diffraction(XRD) and UV-VIS-NIR spectroscopy. XRD studies revealed that the sample was polycrystalline in nature. The SEM image showed that the sample is columnar in structure and the grains are uniform. Optical band gap of the CdTe thin film was estimated from transmittance and reflectance data and it was found 1.53eV.The structural, optical and surface properties of the film showed that the CdTe thin film materials can be used for fabrication of CdTe thin film solar cell

A STUDY ON EPIPHYTIC LICHENS FROM PRUNUS PERSICA

 Objective: The objective of this study is to explore and identify the epiphytic lichens on the tree bark of Prunus persica from Kodaikanal area and analyze its phytochemical properties.Methods: Samples were collected from Kodaikanal area, identified by morphological and chemical constituents. Macromolecules present were quantified by DNS method, Lowry's method, and lipid tests. The secondary metabolites present were analyzed by standard phytochemical tests and thin-layer chromatography.Results and Conclusion: It was interesting to observe that species belonging to the lichen genera - Parmotrema, Ramalina, and Usnea dominated the area. The samples have been identified and deposited in LWG herbarium, NBRI, Lucknow. As lichens form an ideal model to study the humongous secondary metabolites present in it, a preliminary investigation was performed to understand the nutritive value as well as phytochemicals present in the lichens. The results indicate that these organisms can be of potential medicinal value with Ramalina and Usnea species contributing good amount of macronutrients present in them, while qualitative analysis of phytochemicals reports all the lichens for enormous metabolites

Reversible antifertility effect of Opuntia elatior Mill. fruit extract

Background: This study was undertaken to evaluate the male antifertility potential of the fruit extract of O. elatior and its reversibility.  Methods: The methanol fruit extract was administered orally (300, 900 mg/kg bw) to male rats for 60 days, and fertility was assessed by analysing spermatogenesis, epididymal sperm count, serum testosterone levels and testicular hydroxysteroid dehydrogenase activity. Fertility was assessed by mating treated rats with normally cycling virgin females. Reversibility of fertility suppression was studied by withdrawal of treatment for two weeks.Results: Epididymal sperm count and motility was markedly reduced up to 75-80% in rats treated for 60 days, without commensurate decline in serum testosterone levels. Testicular steroidogenesis was not affected as evident by the hydroxysteroid dehydrogenase activity. Fertility of the treated rats was suppressed when mated with normally cycling virgin female rats without affecting libido. The fertility suppression was dose-dependent being 100% in the highest dose. Withdrawal of the treatment for two weeks led to recovery of the epididymal sperm count, testicular HSDH activity, serum testosterone levels and the fertility.Conclusions: The methanol extract of the fruit of O. elatior shows reversible male antifertility activity without affecting the serum testosterone levels and libido

Nonimmune hydrops foetalis (NIHF): value of fetal autopsy and comparison with ultrasound findings

Background: Nonimmune hydrops foetalis (NIHF) is a terminal catastrophic event of pregnancy caused by numerous diverse etiology. The aim of this study was to assess the significance of foetal autopsy and to compare the prenatal ultrasound (USG) and foetal autopsy findings in cases of NIHF.Methods: All perinatal autopsies performed at the department of pathology between March 2011-February 2018 were retrospectively reviewed. Of the received 130 autopsies, twenty cases of NIHF were identified, records of which were collected and correlated with maternal medical history, prenatal imaging and autopsy findings.Results: The malformations with hydrops foetalis were classified according to the involved organ system. They were cardiothoracic (7/20 cases), genitourinary (3/20 cases), gastrointestinal lesions (1/20 cases), chromosomal (4/20 cases) and multisystem anomaly/syndromic association (5/20 cases). Complete agreement between USG and autopsy was seen in 8 (40%) cases. In 5 (25%) cases autopsy findings were in total disagreement with USG diagnosis. The rest of the 7 (35%) cases, autopsy revealed additional information and changed the recurrence risk in two cases.Conclusions: Present study demonstrates the high rate of discordancy between USG and autopsy examination in cases complicated by NIHF. Foetal autopsy confirms the USG findings (quality control/audit), adds additional findings or changes the final diagnosis, which helps in redefining the recurrence risk and plausible genetic counselling for future pregnancies. Hence present study underscores the need for autopsy in all cases of NIHF