Decline in human sperm counts during the past 50 years?

There is widespread concern that environmental pollutants acting as xenoestrogens may affect human fertility adversely. Whether this has already made an impact on human fertility worldwide remains debatable at the present stage. Ever since Carlsen's analysis reported that sperm concentrations have decreased over the last 50 years there has been renewed attention and curiosity amongst peer groups in different parts of the world. Though Carlsen's mode of data analysis was criticized on many fronts, a number of similar studies that appeared subsequently have contradicted each other. The article has reviewed the literature to determine whether semen counts have indeed changed in the past 50 years. We conclude that sperm counts vary enormously between different countries or regions of the world and also between individual men. There is even marked variation between counts on the same men. It is therefore not surprising that not all analyses of sperm counts find the same patterns. We suggest that a well ­designed prospective study should be performed in several different regions of the world in order to extrapolate the results on sperm counts and to evaluate the potential effect of external factors on male reproductive health. It is hoped that the conclusions from these new studies might put an end to the controversy that surrounds this issue.peer-reviewe

Presowing hardening of the host with phenolic acids reduces induction of seed germination in the root parasite Striga asiatica

S. asiatica, A root parasite, causes severe loss of yield in sorghum and several other crops. The seeds of the parasite are induced to germinate by a stimulant in the host root exudate. Presowing hardening of the host with vanillic acid [121-​34-​6]​, caffeic acid [331-​39-​5]​, and ferulic acid [1135-​24-​6] (25 ppm) reduced the induction of seed germination in the parasite by the host root exudate. The treatment caused a slight improvement in the dry matter prodn. in the host and in addn., increased the phenolics level in the host root exudate. The latter effect might be responsible for reducing germination in Striga

Allelopathic effects ofParthenium hysterophorus L.

Association withParthenium hysterophorus L. caused retarded growth and nodulation in bean (Phaseolus vulgaris var. ‘Burpees Stringless’) the inhibition decreasing with increasing distance from the weed. Leachate collected from Parthenium grown pots also caused similar inhibition in bean growth. The inhibitory nature of the root exudate was confirmed under sterile cultural conditions by its effect on wheat (Triticum aestivum var. ‘UP301’) seedling growth. At the rosette and flowering stage of the weed there was maximum exudation of inhibitors which remained active for about thirty days

Allelopathic effects of Parthenium hysterophorus L - Part IV. Identification of inhibitors

Analysis of the inhibitors from allelopathic species of Parthenium hysterophorus L. revealed that sesquiterpene lactones and phenolics formed an important group of water soluble compounds involved in allelopathy. Parthenin was the major sesquiterpene lactone involved though dampsin was also found in traces. Caffeic acid, vanillic acid, ferulic acid, chlorogenic acid, and anisic acid among the phenolics and fumaric acid among the organic acids were the important constituents of the air dried parts of the plant, many of them being traced in the root exudates, leaf washings, pollen and trichome leachates. © 1980 Martinus Nijhoff Publishers

Allelopathic effects of Parthenium hysterophorus L - III. Inhibitory effects of the weed residue

Growth toxins are released to the soil through leaching and during decay from the air-dried parts of Parthenium hysterophorus L. The dry leaves mixed to the soil inhibit nodulation and growth in legumes, branching in tomato (Lycopersicum esculentum L. cv. 'Pusa Ruby'), plant height and tillering in ragi (Eleusine coracana Gaertn. cv. 'Poorna'), and yield in bean (Phaseolus vulgaris. L. cv. 'Burpees Stringless'), cowpea (Vigna sinensis L.), tomato and ragi, but have stimulatory effect on bajra (Pennisetum typhoideum Rich cv. 'H.B.1'). The inhibitors released to the substratum remain active for about thirty days. © 1979 Martinus Nijhoff Publishers

Allelopathic effects of Parthenium hysterophorus L. - I. Exudation of inhibitors through roots

Association with Parthenium hysterophorus L. caused retarded growth and nodulation in bean (Phaseolus vulgaris var. 'Burpees Stringless') the inhibition decreasing with increasing distance from the weed. Leachate collected from Parthenium grown pots also caused similar inhibition in bean growth. The inhibitory nature of the root exudate was confirmed under sterile cultural conditions by its effect on wheat (Triticum aestivum var. 'UP301') seedling growth. At the rosette and flowering stage of the weed there was maximum exudation of inhibitors which remained active for about thirty days. © 1979 Martinus Nijhoff Publishers

Improved digital watermarking schemes using DCT and neural techniques

The present thesis investigates the copyright protection by utilizing the digital watermarking of images. The basic spatial domain technique DCT based frequency based technique were studied and simulated. Most recently used Neural Network based DCT Scheme is also studied and simulated. The earlier used Back Propagation Network (BPN) is replaced by Radial Basis Function Neural Network (RBFNN) in the proposed scheme to improve the robustness and overall computation requirements. Since RBFNN requires less number of weights during training, the memory requirement is also less as compared to BPN. Keywords : Digital Watermarking, Back Propagation Network (BPN), Hash Function, Radial Basis Function Neural Network (RBFNN), and Discrete Cosine Transform (DCT). Watermarking can be considered as a special technique of steganography where one message is embedded in another and the two messages are related to each other in some way. The most common examples of watermarking are the presence of specific patterns in currency notes, which are visible only when the note is held to light, and logos in the background of printed text documents. The watermarking techniques prevent forgery and unauthorized replication of physical objects. In digital watermarking a low-energy signal is imperceptibly embedded in another signal. The low-energy signal is called the watermark and it depicts some metadata, like security or rights information about the main signal. The main signal in which the watermark is embedded is referred to as the cover signal since it covers the watermark. In recent years the ease with which perfect copies can be made has lead large-scale unauthorized copying, which is a great concern to the music, film, book and software publishing industries. Because of this concern over copyright issues, a number of technologies are being developed to protect against illegal copying. One of these technologies is the use of digital watermarks. Watermarking embeds an ownership signal directly into the data. In this way, the signal is always present with the data. Analysis Digital watermarking techniques were implemented in the frequency domain using Discrete Cosine Transform (DCT). The DCT transforms a signal or image from the spatial domain to the frequency domain. Also digital watermarking was implemented using Neural Networks such as: 1. Back Propagation Network (BPN) 2. Radial Basis Function Neural Network (RBFNN) Digital watermarking using RBFNN was proposed which improves both security and robustness of the image. It is based on the Cover’s theorem which states that nonlinearly separable patterns can be separated linearly if the pattern is cast nonlinearly into a higher dimensional space. RBFNN contains an input layer, a hidden layer with nonlinear activation functions and an output layer with linear activation functions. Results The following results were obtained:- 1. The DCT based method is more robust than that of the LSB based method in the tested possible attacks. DCT method can achieve the following two goals: The first is that illegal users do not know the location of the embedded watermark in the image. The second is that a legal user can retrieve the embedded watermark from the altered image. 2. The RBFNN network is easier to train than the BPN network. The main advantage of the RBFNN over the BPN is the reduced computational cost in the training stage, while maintaining a good performance of approximation. Also less number of weights are required to be stored or less memory requirements for the verification and testing in a later stage