Fluorescence Spectroscopy: History, Principle and Application – Part-III

Fluorescence spectroscopy has been applied to numerous analytical, bio-analytical, environmental, clinical and forensic investigations. There is a need for a highly sensitive detection tool that can replace the expensive and difficult to handle radioactive tracers, but at the same time the tool/method has to be of low cost, easy to handle and can detect analytes in rapid time. Fluorescence spectroscopy has answer to all these. Fig1_Fluoro_part 3To explain the highly sensitive detection capacity of fluorescence as a tool, Professor J.R. Lakowicz discussed an example in his book “The Principles of Fluorescence Spectroscopy”. He mentioned that since fluorescence intensity is measured directly in relatively dark background (see the inset figure) without the presence of bright reference beam as in case of absorbance, it becomes easy to measure even in low level of light, and electronic impulses of the single photon can be read by the most photomultiplier tubes.1 On the other hand, if we try to measure the absorbance of a solution of concentration 1 nanomolar  (10-10 M) with molar extinction coefficient (e) of 10-5 M-1 cm-1, the absorbance will 10-5 per cm (%transmission= 99.9977). It is very difficult to measure only 0.0023% absorbed light even with highly sophisticated optical system. Following two schematic diagrams represent very basic model of UV-vis and fluorescence spectrophotometer which will help us to understand the technical difference between these two techniques regarding the sensitivity in measurement as explained above. This explains the high sensitivity of fluorescence spectroscopy as a detection tool.

Fig2_Fluoro_part 3

Fluorescence based sensing technologies have been constantly growing with the invention of innovative methods and materials. I will discuss various applications based on fluorescence detection/sensing. Before that, we need to understand the different characteristics of fluorescence emission such as Stokes shift, fluorescence lifetime and quantum yield, steady and time-resolved fluorescence, fluorescence anisotropy, fluorescence quenching, fluorescence resonance energy transfer (FRET), and the molecular information obtained from these.

Fluorescence emission spectrum and Stokes shift

Stokes shift is the difference between the position of absorption band maximum and emission maximum of the same electronic transition in frequency or in wavelength unit (inset figure below). Fig3_Fluoro_part 3Fluorescence always occurs at the higher wavelength than the absorption. The reason can be attributed to the relaxation of the excited electron from the higher vibration energy level to lower vibrational level of S1 and further decay to higher vibrational energy level to S0. Thus, the excitation energy is lost by the thermalization of excess vibrational energy. Irish Physicist, Sir G. G. Stokes first reported this phenomenon in 1852. In addition to this, further Stokes shift can be observed due to solvent effect, pH, excited state reaction, complex formation and energy transfer. From the measurement of Stokes shift, different molecular information can be obtained. As fluorophores are generally sensitive to the environment, by examining the position and intensity of the emission spectrum location of moleculer probe (here the fluorophore attached to some macromolecules) inside a macromolecule can be identified. The property of certain fluorophore being weakly Fig4_Fluoro_part 3fluorescent in aqueous environment but strongly while binding to target biomolecule accompanied by Stokes shift has been widely used. Moreover, utilizing the environment sensitivity of certain flurophores for example indole group of tryptophan residue in protein may reveal whether the protein is in folded or unfolded (denatured) state. Emission from a residue shifts to longer wavelength once it is exposed to the surrounding solvent (here water) due to unfolding. In the folded state, the protein shields it from the solvent. Therefore, conformation of proteins can be obtained from emission intensity and Stokes shift (see the inset figure at the left).

I will talk about the other characteristics along with applications in the future posts. Continued……………


Fluorescence Spectroscopy: History, Principle and Application – Part-II

In this part, I will discuss some basic theories behind Fluorescence spectroscopy. In order to realize the potential of this particular spectroscopic technique, one must aware of the principle based on which this technique works. This will allow one to take complete advantage of this sensitive technique in applying in various scientific research.

Spectroscopy, in general, is applied quantum mechanics. Without going deep into the mathematical part, I will try to explain the basic principle of fluorescence spectroscopy rather qualitatively using Jablonski diagram.

Basic Principle of Fluorescence Spectroscopy:

Professor Jablonski, known as the father of fluorescence spectroscopy presented us with a diagram which describes various molecular processes in the excited state. As mentioned in my last blog that fluorophores play the central role in fluorescence. Prior to excitation with light (or photon), the electronic configuration of the fluorophore molecule is described as ground state. Upon absorbing  Jablonski diagram_finalphoton the electrons of the fluorophore molecule get raised to higher energy electronic level. The phenomenon of fluorescence occurs when the excited electron comes back to the ground state from the higher electronic energy level by emitting photon. A typical Jablonski diagram is basically an energy level diagram which illustrates electronic states of a molecule and transitions between them. The electronic states are arranged vertically by energy and grouped horizontally by spin multiplicity (see the inset diagram). Radiative transition is depicted by solid arrows, while the nonradiative transition is shown by squiggly arrows. Within each electronic state there are multiple vibrational energy levels (electronic levels are depicted with thicker lines and the vibrational levels are with thinner lines). As shown in the inset figure, the singlet ground, first and second electronic excited states are depicted by S0, S1 and S2, respectively, while first and second triplet excited states are depicted by T1 and T2, respectively. In singlet state, all the electrons of a molecule have their spin paired, while in triplet state, one set of electron spin becomes unpaired. These two states differ in properties as well as in energies; the triplet states always lie in lower energy than its corresponding singlet state. The transition between singlet to triplet state is forbidden. The probability of singlet-triplet process is 10-6 of the singlet-singlet and triplet-triplet processes.

The first transition in the Jablonski diagram is ABSORPTION. When a fluorophore molecule (or any molecule of interest) absorbs photon of definite energy the electrons in the ground state (S0) is excited to a higher energy level (S1 or S2) depending on the amount of energy absorbed. The process is very fast, and the time scale of absorption is in the order of 10-15 seconds. Once the electron is excited, there are multiple processes by which it dissipates energy and return to the ground state. First through VIBRATIONAL RELAXATION (VR), a non-radiative by which the electron gives away the energy in vibrational mode in the form of kinetic energy, and returns to lowest vibrational level of the corresponding excited electronic state. The Time scale Table time scale of VR is in the order of 10-14-10-11 seconds. Another process of energy dissipation occurs via INTERNAL CONVERSION (IC). IC is mechanistically similar to VR, and it occurs when vibrational level strongly overlaps with the electronic level, the electron in the vibration level of higher excited electronic state may relax to the vibrational level of the lower excited electronic state. However, due to lack of overlap between the vibrational and electronic levels and a large energy difference between ground state and the first excited electronic state, the probability of an electron to return to ground state via IC is very less. FLUORESCENCE (Fl) is another path through which an electron can dissipate energy and return to ground state. The time scale of fluorescence is in the order of 10-9-10-7 seconds. From the lifetime, one can tell that IC is generally complete before emission. Fluorescence emission generally results from thermally equilibrated lowest energy vibration level of S1 to the highest energy vibration level of ground state (S0), Anthracene abs and emission which then quickly thermally equilibrated (VR), and returns to the lowest energy vibration level of ground state. This singlet-singlet transition is allowed. Since emission involves the transition to highest energy vibrational level of ground state, the emission spectrum is typically a mirror image of absorption spectrum of the S0 → S1 transition. Electronic transition does not alter much the nuclear configuration, so the spacing between the vibrational energy level of the excited state remains almost the same as in ground state. This is the reason behind the similar vibrational structure of absorption and emission spectrum of a fluorophore molecule. However, there exists many exception of this mirror image rule. In case of proton dissociation, excited state reactions, charge-transfer complex formation, dimerization, one can observe deviation from the mirror symmetry rule.

Another process of non-radiative energy dissipation is known as INTER SYSTEM CROSSING (ISC) which involves a forbidden transition, where the electron changes spin multiplicity from excited singlet state (S1) to excited triplet state (T1). The emission from T1 to singlet ground state (S0) is known as PHOSPHORESCENCE and this forbidden transition is associated with several order smaller rate constant than that of fluorescence. The lifetime of phosphorescence is quite longer, in the order of 10-4 second to 1 minute.


1. Jihad René Albani. Principles and Applications of Fluorescence Spectroscopy. Blackwell Science Ltd, 9600 Garsington Road, Oxford OX4 2DQ, UK. Edition 2007.

2. Joseph R. Lakowicz. Principles of Fluorescence Spectroscopy.Third Edition. Springer.


Fluorescence Spectroscopy: History, Principle and Application – Part-I

Fluorescence spectroscopy, a very sensitive analytical tool, has wide ranges of application in various disciplines of scientific/medical research. I am going to write a series of blog-posts discussing its numerous applications. To begin with, let me first go back to the history; how “FLUORESCENCE” was discovered, and evolved as a primary research tool in diverse fields of scientific research such as chemistry, biochemistry, biophysics, biotechnology, genetics, forensic, medical diagnostics, etc. to name a few.

A Short History of Fluorescence:

Nicholás Monardes, a Spanish physician and botanist observed a bluish opalescence from water infusion of a wood of a small Mexican tree. In 1565, he described about this observation in the Historia medicinal de lascosasque se traen de nuestras Indias Occidentales. A Franciscan missionary named Bernardino de Sahagún also independently observed similar observation for the wood named “coatli”, around same time. He reported in the Florentine Codex, “Coatli …..patli, yoanaqujxtiloni, matlaticiniayoaxixpatli..“, which means “it is a medicine, and makes the water of blue color, its juice is medicinal for the urine”. In 1574, Charles de L’Écluse, a Flemish botanist named Monardes’s wood as Lignum Nephriticum (kidney wood) because of its therapeutic properties in treating kidney related ailments. Thereafter, many scientists reported this type of luminescence property in various substances such as chlorophyll, barium sulfate, etc. Sir John Frederich William Herchel first observed the fluorescence from a solution of quinine sulfate (in tartaric acid) in sunlight in 1845, and described it as “beautiful celestial blue color”. This was published in Philosophical Translation of the Royal Society of London (1845) 135:143–145. Sir John Herchel termed this phenomenon as “epipolic dispersion”. [Inset figure shows the fluorescence image1 from a quinine sulfate solution.] Later in 1852, G.G. Stokes published a very long article (more than 100 pages), “On the change of Refrangibility of Light”, where he mentioned about his disagreement on Sir John Herchel’s term of “epipolic dispersion”, and wrote; “I confess I do not like this term. I am almost inclined to coin a word, and call the appearance fluorescence from fluor-spar, as the analogous term opalescence is derived from a mineral.” G.G. Stokes was the first person who proposed to use fluorescence as an analytical tool in a lecture “On the application of the optical properties to detection and discrimination of organic substances” in 1864. Following are the important research works done in much earlier days (1904-1942), which immensely contributed to the understanding, improvement and advancement in Fluorescence spectroscopy as a technology.

1905: The first excitation spectrum of a dye – E. Nichols and E. Merrit

1919: Fluorescence quenching – Stern and Volmer

1924: Determination of fluorescence yield -S.J. Vavilov

1925: Theory of fluorescence polarization-F. Perrin

1926: First direct measurement of nanosecond lifetime – E. Gaviola

1935: Jablonskidiagram – A. Jablonski

1948: QM theory of dipole-dipole interaction – T. Förster

Fluorophores are mainly organic compounds which play the central role in fluorescence. They not only absorb light of specific wavelength, but also emit light at specific wavelength. The energy of this emitted light depends on the fluorophore as well as on the surrounding environment of the fluorophore. R.Meyer in 1897 first coined the term “fluorophores” to describe those compounds or the specific image2 functional groups responsible for the phenomenon of fluorescence. A lot of fluorophores has been discovered such as fluorosceine, eosine, quinine, rhodamine, acridine, etc. to name a few. The first fluorometric analysis was performed by F. Goppelsröderin 1867 for the quantitative determination of Al(III) from the fluorescence of its morin chelate. Otto Heimstaedt and Heinrich Lehmann (1911-1913) first developed the fluorescence microscope to investigate the autofluoresecence of biosamples such as bacteria, protozoa, plant, and animal tissues. Later, American Instrument Company (AMINCO) collaborated with Dr. Robert Bowman who designed the instrument and marketed first ever spectrophotofluorimeter (SPF) in 1956 (inset picture) (http://history.nih.gov/exhibits/bowman/HSfluor.htm). Antimalarial research actually initiated the invention of a spectrophotofluorimeter as an analytical instrument which can determine the presence of analytes which fluoresce. The story dated back to 1940, during World War II, when scientists in USA required to determine the amount of drug reached to the malaria parasites in patient’s blood for a clinical trial of antimalarial drugs. Bernard Brodie and Sidney Udenfriend of Goldwater Memorial Hospital in New York City designed a new test using an instrument called fluorimeter which can determine the amount of the drugs in the blood plasma from the intensity of the fluorescence emitting from the drug, since many of the drugs used in the trial fluoresce. This helped them to come up with a critical dose of a drug minimizing the adverse side effects. Atabrine was one such promising drug which destroys malaria parasite effectively. Scientists at Goldwater realized that this technique has immense potential in scientific research, and needed a better instrument to utilize the full potential of this new spectroscopic technique. Dr. James Shannon, the leader of antimalarial research at Goldwater became the first director of NIH (National Institute of Health) at Bethesda, Maryland, USA, and recruited a team of scientists to design a new instrument utilizing the principles of fluorescence. Dr. Robert Bowman led this team and came up with the design of first spectrophotofluorimeter. Invention of spectrophotofluorimeter was indeed an exciting journey which started with a need to destroy the malaria parasite effectively.  This is another example of the famous English proverb “Necessity is the Mother of Invention”.

Come back to know more about fluorescence. In a series of posts, I will explain basic principles of fluorescence spectroscopy and its various applications in a qualitative manner, which may help beginners to understand the potential of this particular spectroscopy in scientific research.


Place Names: Geographical Renaming and Historical Context

Place names of several major cities, roads, flyovers, bridges, airports, and even small and insignificant chowks in nascent cities and towns have had a “makeover” in modern times. Most of these changes in place names have been effected almost as an afterthought and a sudden revitalization of regional pride.

The protagonists of the changes in place names would perhaps argue that this regional pride was always there, but a change in place names nearly always brings in controversy and therefore takes years to implement.  This might yet be true, and I have no qualms with regional pride as long as it does not impinge on the rights and interests of citizenry across the country. After all, culture in many parts of India is nurtured through a pride in the province and its heritage. Regional arts, crafts, and other expressions of originality in a state not only bind the region with a homogeneous cultural identity by which it receives recognition from other parts of the country, but also represent that state in the international arena. Delhi Chaat, vada pao and bhelpuri, appam, masala dosa, Bengali sweets, Karachi halwa, Banarasi paan, Kacchi dhabeli, and Hyderabadi biryani—the list is endless—are some culinary expressions of that regional pride, which is the identity of a particular city or region.

Place Names as Signage of History

Similar channels of identity can be found in textiles, dance, art, language, etc. Regional pride, therefore, might not be a bad thing at all, and changes in geographical names to preserve— or remind—the people about a particular region’s “originality” can thus be acceptable. But simultaneously, it might be argued that a place name is not just a dot and line on a map, but also a veritable identifier of settlements, civilizations, migrations, and reference points of history. Modernity has reduced these points of reference to relatively modern relevance only, feigning a cultural amnesia and shortening the life of the place, in a way.

The new place names that now find place on the map— undoubtedly after a bitter struggle to bring about the change—evoke nostalgia (the “regional pride”) of a few centuries at most. On the contrary, the names of yore go back manifold in time, recounting a history that is far more time elastic; millenniums, not just centuries, are associated with them. Naturally therefore, the “bias” of the historian—the writer included—generally lies with old nomenclature, simply because the old names conjure up imageries that paint a more complete picture of a particular place or region.

Change in a Place Name: The Psyche

It is not just in India that historical place names are being obliterated from the modern map. Starting from the 1820s, and through the 1990s, at least 38 countries and territories have shed their old place names for the new, and 66 cities globally are now known by their new names. India, too, seems to be afflicted by this trend; there are at least seven or eight major Indian cities that have seen a name change in modern times.

What, then, is the psyche behind this urge to change a toponym? The prime reason, as mentioned earlier, is to reinstate regional pride. In several cases, the changes were brought about by the end of colonial rule and establishment of a nationalistic fervor; in others, mergers or splits necessitated a change; in still others, cumbersome or unusual names were given up for more suitable or easier-sounding names. All these reasons are based on the fact that the “right” to a place name lies with the people who reside there, and their sentiments need to be respected.

Place names have changed, but “geographical souvenirs” of the discarded names still survive. Bombay is now Mumbai, but it is still the Bombay High Court, IIT Bombay, and Bombay Stock Exchange; Madras is now Chennai, but it is still University of Madras, Madras Stock Exchange, IIT Madras, and Madras High Court, Peking is now Beijing, but it is still Peking University; Pusan is now Busan, but it is still Pusan National University… Why? Obviously because established conventions die hard, regardless of the constant urge to move ahead and change the status quo.  And what does a name change hope to achieve? In the last decade of the 16th century, William Shakespeare expressed this sentiment:

“What’s in a name? That which we call a rose by any other name would smell as sweet.”

Romeo and Juliet (II, ii, 1-2), 16th century

And half a millennium later, we need to ask an almost identical question: Will a change in place name alter anything concrete in the people who live and react in a particular place? As former UN diplomat Shashi Tharoor writes:

The trains in Chhatrapati Shivaji Maharaj Terminus will be just as crowded as in VT…. The weather will be just as sultry in Chennai as it used to be in Madras. But are we Indians so insecure in our independence that we still need to prove to ourselves…that we are free?


Infrastructure, Evidence and Interpretation: Economic Fabric in Early India (Part Two)

In an earlier post, I discussed the problem of migration and agricultural output in early India. But besides agriculture, other economic activities in early India depended on similar factors as do economic activities in our times. For instance, let’s focus on infrastructure. Can you imagine a world without bridges, means of transport and communication, buildings, mints, dams, and roads? Where would our economy be without such infrastructure? Infrastructure, therefore, is a conditio sine qua non of any budding—or for that matter developed—economy, be it in the era of kings or emperors, or in the era of democracy and the welfare state.

Administrative Infrastructure

A critical economic action that has been engaged in throughout Indian history was the striking of coins, and the expertise with which the dies were carved and struck on minuscule pieces of metal makes it evident that mints constituted a crucial element of the city infrastructure and were located in every major town or trading center. The following extract from a modern work provides an excellent word picture of the mint organization in ancient India:

The mint house in ancient India was perhaps known as bhandagara, whereas the mahabhandagara was functioning just like the modern Reserve Bank….. The office of the bhandagara…had to maintain the establishment and accounts, and mint coins… [It] was headed by a board of Shreshtina









Figure 1. Interior of the Mughal mint in Fatehpur Sikri

For medieval India, we have the masterful documentation in the Dravyapariksha by Thakkura Pheru, mint-master during the rule of Alauddin Khalji (13th century), where detailed information is provided regarding the coins that were arriving at the mint for melting and re-coining, and about the metallic fineness of various coin nomenclature. Part of the infrastructure that housed the mint during the Mughal rule still survives in Fatehpur Sikri near Delhi (Figure 1).

Infrastructure for the Society

Moving to other elements of infrastructure that supported the economic fabric in early India, references to the construction of roadways, reservoirs, canals, forts, and rest houses are quite frequent in literature, and it is little surprise that the Arthashastra refers to such activities as one of the basic duties of the ruling authority:

[The King shall] construct roads for traffic both by land and water, and set up market towns…. He shall also construct reservoirs filled with water either perennial or drawn from some other source. Or he may provide with sites, roads, timber, and other necessary things those who construct reservoirs of their own accord. Likewise, in the construction of places of pilgrimage…

(Arthashastra, II.1)

From Mauryan Emperor Ashoka (3rd century BCE) to Pashtun Emperor Sher Shah Suri (16th century, often called the forerunner of Akbar), all rulers in early India prioritized the building of roads and infrastructure to support travelers:

On the roads also banyans were planted to give shade to cattle and men, mango gardens were planted, and at each half kos wells were also dug; also rest houses were made….

(Ashoka in one of his rock edicts, c. 273-232 BCE)

For the convenience in travelling of poor travellers, on every road, at a distance of two kos, he made a sarai…another road he made from the city of Agra to Burhanpur…and he made one from the city of Agra to Jodhpur and Chitor, and one road with sarais from the city of Lahore to Multan…

(Tarikh-i-Sher Shahi)

The road from Lahore to Multan, then called the Sadak-e-Azam (the Great Road), later formed part of the Grand Trunk Road (Figure 2), which still serves as one of South Asia’s oldest and longest roads stretching over 2500 km. The road has undergone several improvements in the British period and even thereafter, and now extends from Kolkata to Peshawar. Over the centuries, the road has serviced trade and communication, and aided the movement of troops and invaders.






Figure 2 (Left): The Grand Trunk Road in India, Ambala-Delhi section, during the British Raj. Image at http://en.wikipedia.org/wiki/File:GTRoad_Ambala.jpg_







Figure 3 (Right): A passenger train travelling from Bombay to Thane, 1855 Image at http://commons.wikimedia.org/wiki/ File:Dapoorie_viaduct_bombay1855.jpg


Dalhousie’s stint as Governor General in the mid- 1800s represents a watershed as far as the history of communication infrastructure is concerned, particularly with the introduction of the telegraph and the railway. Here is how the official website of the Indian Railways records the introduction of the railway in India:

The formal inauguration ceremony was performed on 16th April 1853, when 14 railway carriages carrying about 400 guests left Bori Bunder at 3.30 pm “amidst the loud applause of a vast multitude and to the salute of 21 guns.”

Three locomotives were put in service to cover this distance of 33 km, and a year later the Bori Bunder–Thane route was enhanced with India’s first railway bridge (Figure 3). From three locomotives and 33 km, Indian railways today has about 8,000 locomotives and stretches over 63,000 km across the country.

Clearly, therefore, infrastructure has been a primary economic activity of the administration through all historical epochs. In the 21st century, most cross-state, or even multinational, commercial enterprises and investments are determined by the infrastructural base of the target site. In other words, to attract investment from other states and from abroad, we must first build and expand state-of the-art infrastructural capabilities. No wonder, infrastructure in Mumbai has been compared—albeit in a false sense of regional pride—to Shanghai, and India is struggling to attract foreign direct investment by ramping up, inter alia, airports ports, and the hotel industry, and by repeatedly projecting how India’s infrastructure needs should be prioritized to meet the urban challenges that will be posed by 2050.


Migration and its Impact on Agriculture: Economic Fabric in Early India (Part One)

In absorbing knowledge, the discerning public today is presented with a limitless platter of documents, data, and research analyses to pick and choose from. In all compartments of human interface, the documentation base has reached an unprecedented high. For the researcher, the dangers in such a situation of information overspill are obvious: he is constantly hit with “word pictures” from all directions, and more often than not it is the researcher’s insight that helps absorb the good information and filter out the residue.
For the economic historian, however, such vivid descriptions of economic activity are either missing or enmeshed with irrelevant information, and his job becomes quite mind-numbing. While India is chalking its own path of modernity and breaking new ground in all aspects of economic endeavor—infrastructure, agriculture, industry, trade, the demand and supply equation, and fiscal policies—this post presents a random selection of word pictures that depict activities related to agriculture, irrigation, and migration of farmers at various milestones of Indian civilization.

Migration of Farmers and Agrarian History

India in circa 1500 BCE was a predominantly agrarian economy; 3500 years later, agriculture is even now the largest economic sector in the sense that it still accounts for about 60% of employment in the country, although its share in India’s GDP has been steadily declining (while it was ±17% in 2007–08, this share is likely to decline to 13.7% in FY13). The government is constantly devising new ways and methods to augment agricultural production, just as farmers are engaged in hitting on the right crop to produce. Our hunt for word pictures begins in the Vedic period, to which the first written records belong.


A Rigvedic hymn vivifies the importance of the produce of the land, and agriculture was obviously the mainstay of the Vedic people. The hymn also shows that the Vedic Aryan was well-acquainted with the art of sowing. In fact, several rituals were associated with sowing activity in those times. Besides sowing of seeds and ploughing, Vedic texts also mention other agricultural processes such as proper land usage, irrigation, harvesting, threshing, winnowing, and storage of grains. As we move forward a few centuries to circa 300 BCE, the literature sheds its predominant religious/ spiritual tenor and becomes even more graphic in the description of agricultural practices. The Arthashastra casts a clear picture of the importance of rainfall and irrigation in agriculture, various crops and the cropping pattern, and the harvesting and gathering procedure. Today, when there is a global concern over climate change and changing pattern of the monsoons, it interesting to compare the geographical distribution of rainfall in circa 300 BCE with that of the 21st century.

Region Rainfall recorded in the Arthashastra Rainfall in modern times
Jangala (unidentified, possibly referred to forest land) 16 dronas = 100 cm
Avanti (Malwa, mod. west Madhya Pradesh) 23 dronas = 140 cm 75-100 cm
Asmaka (south of the Vindhyas, in the Deccan plateau 13.5 dronas = 85 cm 40-75 cm
western countries (west coast of India) “immense quantity”
>200 cm


While accepting that the measurement system in early India might only be taken to be indicative, it is still apparent that rainfall patterns have remained largely unchanged over time. A normal monsoon in those days is remarkably close to the pattern today. Thus, the Arthashastra clearly shows the importance of not only adequate amount of rainfall, but also its proper timing and distribution over various parts of the territory. All these three factors are equally important for agriculture, and even a 10% variance in the monsoons can cause havoc with agriculture.


Speaking of irrigation technology in early India, the Baburnama (memoirs of Mughal ruler Babur, 16th century) provides a vivid description of the irrigation devices used in various parts of India. Interestingly, as Irfan Habib writes, the Persian wheel had by this time become the principal means of lifting water for irrigation in northwestern India and the trans-Jamuna region.

agri3           agri2


(Left) Figure 2.  ‘Saharanpore with a Persian wheel for raising water,’ from ‘Views by Seeta Ram from Mohumdy to Gheen Vol. V’ produced for Lord Moira, afterwards the Marquess of Hastings, by Sita Ram between 1814-15. Print at The British Museum Online Gallery

(Right) Figure 3. The Persian wheel on a chilly morning on the Ganges Plain. Photograph: Bret Wallach, © The Great Mirror, 2009 

The wheel continued to be used for irrigation through the Mughal and British periods, and Babur’s graphic description of the wheel, based on his personal observations, is a perfect fit even for the system followed in the 19th century (Figure 2), and the system followed modern times (Figure 3). It is worthwhile to emphasize the major factors that have contributed to the produce of the land through history.

Migration of Farmers

Besides the dependence on monsoons, availability of land in plenty, and irrigation technology, the migration of cultivators was another critical factor. The Baburnama refers to the migration of entire villages, the ease with which new settlements were established, and the setting up of the required economic “infrastructure” in no time. In today’s context, migration is almost entirely to the cities to support urban industry and infrastructure (and of course eke out a living), but in early India setting up new agrarian settlements was a frequent phenomenon. Babur’s reference to migration and new agricultural settlements is not surprising because, even in the 5th century CE, we hear of migrations of farmers and various other occupation groups. The major factor that worked in favor of migration in early India was the availability of land in plenty, unlike the situation today where it is at a premium or not available at all.

Migration of farmers and its impact on agriculture in early India are thus well-evidenced in literature. It will surely be a worthwhile proposition to look at such evidence for other indicators of the economic fabric in early India and juxtapose such indicators with those in modern times.


Scientific writing and Communication: An alternative career option for PhDs and scientists outside research laboratories

Writing is recognized as a popular and esteemed career which existed ever since we could remember the existence of printed literature and books. There are various writing professionals working as writers and editors for media, publishing house, business communications, advertising, government and academic settings and freelance services. Until now, writing has always been considered as a promising opportunity for someone with a background in a language subject. People some time really wonder if scientists can be writers. Surprisingly, nowadays scientific writing is attracting many PhDs who really covet for a change from traditional research career to a better alternative which can be creative and challenging. Many scientists and PhDs now feel comfortable outside their laboratory zone because with time they have gained excellent communication skills while pursuing PhD through endless exercise of oral presentations, publications and thesis writing.

Can scientific writing and communication be pursued as a promising alternative career by PhDs?

Answer is yes! Writing and publishing are actually the essential components of most careers in science, particularly in an academic research setting. Many PhDs are now opting out for it as an alternative career outside routine research laboratories for a livelihood. A long history of scientific journals dated back to1665 proves that researchers have been unquestionably accepted as writers among scientific community. Not to forget that all the science and technology books are authored by scientists with a particular expertise on the subject. Scientific writing is an excellent way to apply one’s life science background to explore a relatively unconventional career track. If one possesses the knack for quality communication and passion for writing, then science credentials can makes him/her a much favored commodity in the media, research facilities, universities, hospitals and pharmaceutical industries. Scientific writing is in fact a broader term that covers a number of communication domains like science journalism, medical reporters, apart from medical writing, technical writing and science marketing writing.

Scientific writing offers a vibrant scope for PhDs in various disciplines, attracting them into an excellent alternative to a research based career:

The scope of scientific writing has been increasing such that many higher academic institutions like MIT, University of California, Santa Cruz, Johns Hopkins University and Boston University started offering a one-year graduate program in scientific writing. Many management institutions offered short-term courses on technical writing, mainly focusing on writing and editing highly specialized material for biotechnology, pharmaceutical and computer companies. Similar to a scientific writer, a medical writer with a MD or PhD in life or other basic sciences can work for hospitals, pharmaceutical companies, government agencies, medical schools, non-profit organizations or publishing houses. Typically science writers in these settings are known as Public Information Officers (PIO).

One can envision the following few selected options (as mentioned below).

Publishing house: In last few decades, the increased research funding and activities have led to the ever increasing number of scientists in both basic and applied sciences. The growing competition among scientists to perform quality research and avail research funding from government agencies have made it mandatory to publish in high quality journals. With the introduction of first peer review journal in early 17th century, the number of such quality journals has been increasing and so are the career prospects in publishing house where most scientists with PhDs would fit in according to their area of expertise. By combining vigorous research training and subject expertise with their excellent communication and writing ability, scientists can actually find good placements with reputed publishing house as reviewers, copy editors and proofreaders. Though still few in number, there are companies which hire scientists as in-house editors to ensure quality editing, proofreading and prepublication services to authors from non native English speaking countries.

 Regulatory affairs: Various pharmaceutical giants like Novartis, GlaxoSmithKline and Pfizer now exclusively hire scientific, technical and medical writers with excellent writing skills on various positions based on their qualification and experience. Great deal of accuracy is required to prepare the clinical study protocols, regulatory documents and brochures for investigative drugs and thus apart from the subject depth and expertise, rigorous training a PhD received during a five to six year period makes them a perfect fit for such job requirements.

Academics and Research Institutes: Universities and research institutes now specially requires PhDs for different writing tasks which involves helping faculties and scientists in writing research grants in correct format and ensure a quality check before it goes to the funding agency. Such positions include titles like Grant manager, which saves ample time of scientists in dealing with complexities of research grant applications. Many institutions have started elective course on “scientific writing and communications” to better prepare science and medical graduates for their future careers. Similarly, hospitals involved in clinical research, hires PhDs for clinical data writing and various other writing tasks.

Apart from these, one can also try their hands on in careers like freelancing, patent writing and science journalism, which requires a sound technical knowledge and subject expertise. These jobs ensure one’s career satisfaction by offering substantial job flexibilities and attractive salaries.


Content Writing

Some people have unique talents, while some have interesting skills. Everyone is a master of something or the other. Where some are outstanding at sports, some are bright in studies. Similarly, some have a natural gift for writing, which when given proper guidance could be turned into a significant career. Content is undeniably sovereign while considering web-verse. Be it web-content, sales writing, SEO writing, magazine article writing, corporate-profile writing, press-release writing, e-books, etc. With so many varieties of areas depending on content writing, one should integrate the proper skills and techniques required for content writing. Besides, by following some specific guidelines for content writing, one can efficiently write a piece of content that not only attracts readers, but also ranks fine on the search engines.

In order to help you in improving your content writing skills, the present post on ‘Content Writing’ provides some basic points to keep in mind while writing any content.

Points to Remember for Content Writing

Clear and Concise

  • Ensure that the content is understandable and to the point.
  • Before starting to write, always be clear about the target audience.
  • For example, while writing a product description for any household electronic instrument, avoid using showy words and phrases. Instead, use simple words and phrases that can be easily understood.
  • While, writing content about any software or similar product, which usually has potential clients being IT firms, etc., try using a bit of complexity in your content.
  • Always ensure to get down to business at once. The content should reveal the frame that particular product would present to the business.


  • Ensure that you are well-versed on the topic you are writing the content on.
  • In case of any doubts, don’t hesitate in searching and exploring the vast knowledge provided on the internet.
  • Preferably spend some time in researching and exploring on the concerned topic in order to incorporate certain points about which the general audience knows.
  • In order to avoid putting any kind of repetition or plagiarism or outdated information, it is always safer to conduct a bit of research before content writing.


  • Search engine optimisation, better known as, SEO services provide the way to popularise your website or business in the world of prospects and global exposure provided by the internet.
  • SEO services assist the website for securing a high search engine ranking, which is one of the most significant means for your prospective clients to track you.
  • Naturally, the emphasis should be on excellence and quality, but one should not forget the search-engine factor.
  • Avoid filling the content with unnecessary keywords. Instead, ensure to include as many keywords as possible as long as it doesn’t seem to be too apparent.

Content writing may seem an easy job, but it has got depth that needs to be explored. Hence, content writing should be approached with a reasonable bit of carefulness. Certain websites and service providers demand certain types of content. So, while conducting your exploration and SEO, do give consideration to the quality of your content.

By keeping in mind these basic points, one can for sure do really well in content writing. Although content writing is not rocket science, it still needs some research and caution in order to produce an impressive piece of content.


Works Cited Page in MLA Style

MLA-style formatted research or academic papers should have a ‘Works Cited’ page. This works cited page in MLA style should begin as a separate page at the last part of the paper. The present article on ‘Works Cited Page in MLA Style’ presents useful tips to help you learn the modes by which you can format the works cited page in MLA style.

Some of the most basic formatting features of the Works Cited page are discussed below.

Tips for Formatting Works Cited Page in MLA Style

General rules

  • Keep 2.5 cm margins. Insert the last name and page number in the header as in the rest of the paper.
  • Entitle the section as ‘Works Cited’. The title should be centre aligned on the first line of the page.
  • The title should be typed in a standard font and size. It should not be underlined, put in quotation marks or italics.
  • Ensure to double-space the whole manuscript. Avoid inserting extra lines in-between the entries.
  • Ensure to capitalise every word in the titles of the texts, excluding articles, prepositions and conjunctions.
  • Ensure to list all entries in the alphabetical order.
  • For the titles of autonomously published works, like books or journals, use italics or underlining.
  • For the titles of manuscripts published as part of collections, like poems, articles, etc., use quotation marks.
  • Ensure to use a hanging indent for each new entry.

General Entries in a Works Cited Page in MLA Style

  • Book with a Single Author:

Last Name, First Name. Title of Work. City: Publisher, Year.

  • Book with More than One Author:

First Author’s Last Name, First Name, and Second Author’s First Name Last Name. Title of Work. City: Publisher, Year.

  • Journal Article:

Last Name, First Name. “Title of Article.” Title of Journal. Volume Number.Issue Number (Date): Page numbers.

  • Work in Anthology or Collected Works:

Last Name, First Name. “Title of Chapter.” Title of Work. Ed. First Name Last Name. City: Publisher, Year. Page numbers.

  • Entire Anthology or Collected Works:

Last Name, First Name, ed. Title of Work. City: Publisher, Year.

  • Article with No Author:

“Entry Name.” Title of Work. Edition. Year.

  • On-line Sources:

Author’s name. “Title of Document.” Data about the printed version of the publication. Data about the electronic version of the publication. Last Accessed Date.

  • Text from On-line Academic Journal:

Last Name, First Name. “Article’s Name.” Data about the print version of the publication. Data about the electronic version of the publication. Last Accessed Date and Page URL.

  • Article from On-line Encyclopaedia:

Last Name, First Name. “Article’s Name.” Data about the electronic version of the publication. Last Accessed Date and Page URL.

  • Full Internet Site:

Title of Site. Name of Editor of Site. Electronic Data. Last Accessed Date and Page URL.

  • Complete On-line Book:

Author’s Name. Title of Work. Name of editor, compiler or translator. Electronic Publication Data. Last Accessed Date and Page URL.

The above mentioned formatting styles are the most basic styles used for formatting the Works Cited page in MLA Style. By following these basic tips you can learn and get familiar with the proper and correct formatting style of the ‘Works Cited’ page.


Guidelines for Writing Scientific Article

Good design and simple writing style of a scientific article are very important for getting the work published in a scientific journal. Nowadays, all are busy in their work; they need something that is easy to read and understand quickly. Therefore, it is effective to write a scientific article in a clear and simple way, with as much information as can be provided in a straight-forward and concise style. Following are described the guidelines for writing scientific article in an effective manner.

Effective Guidelines for Writing Scientific Article

Writing the Abstract

  • Abstract is the brief report of the whole article. It should highlight the major and important points covered in the article.
  • Writing the abstract includes summarizing the whole article while providing as much information as possible.
  • Identify the chief objectives, results, discussions and conclusions, and gather them in a single paragraph.
  • Exclude background information, literature review, account of methods, and extra words and phrases.
  • Re-read and revise the abstract to ensure that it conveys only the vital information.

Developing the Outline

  • The idea of an outline is to separate and arrange the topics and arguments of the whole article into smaller tasks in a logical form before writing the final article.
  • Prepare a fundamental message of the article by summarising the paper in one sentence (20-25 words).
  • Describe the sampling method employed and the materials and methods used to conduct the study.
  • Identify the major results and findings. List them in note form.
  • Define the chief conclusions and implications arising from the study.
  • Identify the limitations of the study results. What changes in practice, approaches or techniques would you recommend.
  • List every key point separately. Organize them chronologically by order of importance. Organising method should be plain and coherent.
  • Identify the references pertaining to each and every key point.
  • Prepare the introduction by reading the notes made in the outline. Introduction should begin with the main message, describing the purpose/objective of the study, how the study was conducted, what were the results and their implications.

Preparing the First Draft of Article

  • Combine all the information, i.e., data, references, tables, figures, etc.
  • Decide the journal to which you plan to submit the article. Write and format the article according to the targeted journal.
  • While writing the first draft, include all the chief points and information. Ignore the incomplete sentences and incorrect grammar at this stage.
  • Express yourself clearly through your writing by writing what you understand and how you understand it.
  • Use the headings from the prepared outline. Attempt to write the article in parts. Treat each section as a short article.
  • Take a break from the work. Read the prepared first draft with a fresh approach and viewpoint.
  • Edit or modify or delete, but be prepared to revise the article several times to make the final draft.
  • Wherever possible and applicable, use short sentences, simple and clear words and phrases, small paragraphs denoting single idea.
  • Proofread for clarity and readability. Re-read sentences and paragraphs for lucidity. For a scientific article, paragraphs of about 150 words in length are considered most favorable.
  • Ensure consistency and regularity. An article with more than one author often shares the writing procedures. However, the writing style should be consistent and regular.

The above mentioned guidelines for writing scientific article provide the most basic and common guidelines used while writing any scientific article. By following these guidelines for writing scientific article, one can learn and know how to write scientific articles in an effective and attractive manner.