Because of the growing number of digital data sources -from satellites such as the LANDSAT series to the increasing use of all-digital information distribution networks in the publishing industries -there has been a corresponding explosion in the need to store that data permanently at very high densities such that it can be retrieved conveniently and quickly. In parallel with these developments, the capability of high density optical data storage and retrieval techniques such as holography and optical spot recording to meet these needs has improved as well. Offering data transfer rates of up to 100 Mb /sec (spot recording) to over 1 Gb /sec (holographic) and information storage densities in excess of 100 Mb /in2, these technologies have now made it possible to configure complete systems for a wide range of mass storage requirements. The basic technologies and building blocks required for such systems, the general criteria for converting a mass memory specification to an optical storage system based on it, and examples of both holographic and direct spot systems are described. The present status of the Wideband Holographic Recorder System, with data transfer rates of over 1 Gb /sec, and the MASTAR 1015 bit archival mass memory with information storage densities of over 100Mb /in2, are also reviewed.The last two decades have brought with them an ever -accelerating growth in the amount of information which is accumulated and processed daily throughout the world. This includes such straightforward types of data as conventional text, which can be digitized as ASCII -coded alphanumeric data, and more complex information such as the digitized imagery gathered from satellites such as NASA's LANDSAT series. Data are growing at such a rate that one user has estimated that single facilities storing as much as 1016 bits of information each will be common before the end of the coming decade.' To meet the challenge posed by this incredible data -gathering problem, a number of corporations have built on parallel developments in the area of laser recording to produce specialized high-density data storage and retrieval systems for a wide range of applications. It is the purpose of this paper to outline some of the key concepts behind the many digital optical data storage and retrieval systems available today, and to make some predictions on the direction this field will take in the next few years.HOLOGRAPHIC DIGITAL DATA STORAGE AND RETRIEVAL One of the first types of high density storage systems developed was the holographic data recorder. The initial appeal of holographic recording for permanent data storage was very simple: in the standard Fourier transform holographic recording technique utilized in almost every system of this type, there was a built -in redundancy of the data as recorded on the data record. To illustrate this basic principle, consider Figure 1. On the left side of the figure is an array of spots which are mutually coherent. As the Gaussian
Our planet is facing a wide range of inevitable and unprecedented changes such as, the water and food scarcity to the natural calamities, namely flooding, droughts and rising sea levels. All these global challenges had been addressed through the Sustainable Development Goals (SDGs) drafted by the general assembly of the United Nations. In light of the current population growth, it is difficult to attain the sustainable development using conventional and non-renewable natural resources by remaining within the planetary boundaries of Earth. In order to maintain the environment and ecological integrity, the utilization of renewable living natural resources such as microbes become inevitable. Due to their roles in geo physio-chemical processes and bioenergy transformations, microbes allow 'cradle-to-cradle' model of development using wastewater as a renewable resource. The circular wastewater economy is the sole sustainable method to achieve the SDGs of providing clean water and the sanitation to address the issue of water insecurity. The review presents an inter-connected overview on the roles and functions performed by the prokaryotic (bacteria) and eukaryotic (algae and fungi) microorganisms, which are crucial for attaining the environment sustainability within the planetary boundaries. Apart from the environmental roles of microbes, the review also highlights the importance of human-microbe interactions (gut microbiome) and edible microbial species (algae and fungi) which are essential for developing sustainable future alternatives to human nutrition, well being and prevention of diseases.
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