Revival of Complementary and Alternative Herbal Medicines

Herbal medicines, complementary or alternative medicines is a wide term for the therapies that are not part of standard care but it has many theories regarding efficacy based on personal experiences, history and common knowledge. It has long been used since ancient times since the beginning of human civilization. Its use had caught much attention in the early 1800s, with the development in the science of chemistry, a new era in pharmacotherapeutics and the use of active chemical ingredients in plants which were known to produce favorable therapeutic effects, were explored, active compounds were extracted, purified and their structure was revealed. This advancement paved the way towards modern pharmaceutical therapy. The modern drugs are based on these herbal medicines, after extracting the active and pure chemical compounds. Pharmacokinetics and physicochemical properties of the active ingredients was explored. It lead to the better understanding of efficacy and safety profile of these drugs and first choice for treatment of various diseases. At the same time, the herbal medicines were considered as secondarily important. After approximately two centuries, the use of herbal medicines have seen a revival globally both in developing as well as developed countries. In the past few years, the practice of using herbal medicines as an alternative and complementary health medicine has gained more importance. Herbal medicines are common for treatment of various ailments including cancer, digestive disorders, pain related disorders, neuropathic ailments and cardiac arrhythmias etc. Even it has been used by pregnant females and mostly perceived as safe. Its use has gained more attraction due to its ‘natural’ approach and lesser side effects. Their use if often overlooked but physicians should pay attention to these medicines. There is lack of familiarity, standardization of the drug components, unproven therapeutic effects in various diseases, unexplored toxicology, pharmacokinetics, drug-drug interactions, and compatibility in patients with varying medical, genetic and demographic history. There are serious concerns regarding the safety, efficacy and quality of herbal products and nutraceuticals. Accidental contamination and deliberate adulteration are assumed to be the main cause of the side effects. Much of the herbal medical knowledge is scattered in different regions of the world and mostly available at family, community and local level and mostly in any native languages. There is need of coherent sources, knowledge, and exploration of these medicines across the world. The herbal medicine has varying diversity in different geological regions and they should be investigated. There should be a regional or national body to control and approve the herbal medicines. Proper documentations on these medicines and food supplements should also be done.

Bandpass Sampling Methodology for Uniformly Spaced Multiband Energy-Sparse Spectrum

In this dissertation, a novel direct radio frequency (RF) sampling method is proposed in order to find out the minimum sampling frequency for an evenly spaced spectrum comprising multiband RF signals. The proposed methodology describes a set of rules to achieve the lowest possible sampling frequency rates without any compromise of spectrum folding or overlap of aliases in baseband after down conversion. It is shown that the minimum sampling rate has a unique relation with the layout of the spectrum of interest (SOI). For instance, if there are N number of information bands of equal bandwidth B in the SOI, then it is possible to down-convert the complete SOI using the sampling rate, 2NB, which is twice of the total information bandwidth only if all bands are evenly spaced in the SOI. Another factor introduced to the achieve the minimum sampling rate is the sparseness-nature in the SOI, which is the ratio of null bandwidth to information bandwidth. The proposed methodology is general in nature and is flexible to the number of input signals or bands as well as to their positions in the desired spectrum. In the proposed research work, simulations are carried out that verify that by using the recommended minimum sampling rates, the desired signal is extractable without any additional computational complexity due to spectrum folding or aliasing-overlap. Our proposed methodology has a vast scope in the design of general-purpose receivers, global navigational satellite system (GNSS) receiver and cognitive radios (CR) because of the use of a low speed ADC. Moreover, the same can be efficiently used to monitor a wide band spectrum in military communications especially for electronic warfare receivers, where reduction of the complexity, size and cost has significant importance. As a model application of our proposed work, we present a composite design for the multiband-multistandard GNSS receiver. The design efficacy is based on the proposed bandpass sampling methodology that transforms the sparse-spectrum electromagnetic environment into a quasi-uniformly spaced spectrum of compact bandwidth, which is more appropriate and useful for simultaneous digitization and down-conversion of analogue signals. In this method, only a part of SOI is transformed to an intermediate frequency. In this way, the desired frequency bands of information that are widely spread, are grouped to form a contiguous-spectrum which is quasi-uniformly spaced. There on, a sub- sampling is carried out for simultaneous digitization and translation of input signals to the first-Nyquist zone. The proposed composite architecture is also helpful to circumvent the higher-order intermodulation components. The proposed design is validated for conventional Global Positioning System L1 and L2 bands and also for new L5 band used in GNSS (GLONASS, Galileo and Beidou) receivers. The presented results show considerable reduction in the sampling rates, and improvement in signal-to-noise and distortion ratio, which can be easily managed by a low sampling analogue to digital conversion.