Saturday, August 5, 2017

TM Krishna - The man, his music and his mission

The hall was already full and the concert was already in progress when I walked in to Unnati auditorium. TM Krishna was immersed in delivering Sri Dumburge in Ragam Sriranjani in his inimitable style. I looked for a spot to sit but every inch of the hall including the mat on the floor were filled with people. But I was happy to stand on the last row and soak in the music flowing in from the stage.

Traditionally Carnatic vocalist sits in the middle flanked on both sides by violinist and mridangist. The second percussion artist sits behind the vocalist on the right side. But TM Krishna, known for questioning the tradition, ensured that no artists sit behind him and ensured that everyone is given equal importance on stage. He himself sat in one side rather than in the centre.

Photo credits: Unnati

Over the years TM Krishna has molded a different style of singing, which is refreshingly different from a rather rigid traditional way of performing this art form. He once famously said that he does not perform for his audience, but he performs because he enjoys doing so. On stage as he swings his arms with wide sweeping gestures as he brings out the nuances of a raga, he seems to play with each note of the raga like a skilled juggler. He seems to see those notes floating around him in the air and plucks them with his finger or lifts them or pushes them down as he takes the audience on a wonderful voyage over the waves of the ragas.

TM Krishna, recipient of last year's Magsasay Award, is known not just for his singing prowess but on his concerns for social and environmental issues. For yesterday's concert at Unnati he ensured that he would not use the car provided by the organizers, but instead would come in Metro from the railway station. That sums up the man and his concerns for things around him. That attitude sets him apart from other more gifted artists of his time. No surprise that he took time off to sing a song called Porombokku Padal to highlight the environmental disaster unfolding in Chennai Ennore Creek due to land encroachment.

This is the man who quit Chennai Music Sabhas in an attempt to bring music to common men by starting a new music festival at Urur Olcott Kuppam, a fishermen's colony in Chennai.  His effort to team up with Jogappas, a transgender community who make a living through folk songs and dance, is really commendable.

Carnatic music was born and evolved in temples of south India and almost all compositions are on various daieties. Yesterday, TM Krishna used Ragam Khamboji to sing a song on Palm Tree called "Eeterimele Ekaanthamai Nindrirukkum Panaye". Palm tree is symbolic of the Tamilnadu landscape. It was interesting to hear Carnatic composition rendered on a mundane thing like a palm tree.

His contribution to music goes beyond stage performance. His path-breaking book, A Southern Music - The Karnatik Story, was a first-of-its-kind philosophical, aesthetic and socio-plitical exploration of Karnatik Music. For this he was awarded the 2014 Tata Literature Award for Best FIrst Book in the non-fiction category. 

Saturday, May 26, 2012

B2B



I used to enjoy the comforts of my car, driving to office within the  confines of an air conditioned environment. But two things changed my mindset towards office commute:
  1. One day I was sitting in my car waiting to get out of a massive traffic jam, listening to my favorite music. Then I heard the helpless siren of an ambulence behind me carrying a critical patient. It then struck me hard that probably my yearning for luxury was delaying a medical treatment for that critical patient. Then I thought, what if he dies? Wouldn't I be responsible for it, along with many other drivers around me?!  
  2. The picture below (borrowed and modified from a picture created by the NGO Hasiru Usiru). I hope it requires no additional explanation. 
The above two had a profound impact on me and I stopped taking my car to office completely, ever since. Switching to mass transport was not easy for me initially as it required additional walking to the bus stop and the uncertainty of when the bus comes. But I soon realised that it is a very small sacrifice to a city that gave me so much. It has been 2 years since I have been commuting the 18 km, that separates my home from the office, using BMTC and I would prefer the bus to my car any day.....



  
  So want to be the change?
                                                                                  B2B
B2B stands for Bus to Bannerughatta, an initiative to appeal to BMTC to improve the bus service along Bannerughatta Road.

Sounds interesting? Please continue reading….

In spite of having so many companies, educational institutions and hospitals, the bus service along Bannerughatta Road is comparatively poor. While connectivity from Bangalore City Bus Stand to Bannerughatta is good, surprisingly there is no connectivity to the Metro Station at MG Road. Having spent so much on implementing Bangalore Metro, it is ironic that a main station like MG Road has no bus connectivity to an IT corridor like Bannerughatta Road.

A team of people involved in environment related activities in my company CSG, are planning to write to BMTC to improve the bus connectivity to this road, especially from Shivaji Nagar. But we need to show the commuter demand so as to get easier acceptance by BMTC to this  appeal. So if you or any of your friends work in Bannerughatta road and keen to switch to bus, please drop an email to rbsuresh@yahoo.com with your name, telephone number, company name, home location, time of travel and preferred route by 29 May 2012. I do not know how successful we will be in this endeavor, but at least we must try.

By switching to a mass transport service, we can help the cause of:
  • A critical patient to reach the hospital in time*
  • A traffic constable in managing the traffic
  • Your employer, by improving our collective productivity
  • The nation by reducing the consumption of petroleum, thereby reducing our Current Account Deficit (and making Rupee stronger)
  • The environment, the obvious beneficiary
  • Above all, Yourself, as you will reach office/home less tired and less stressed**. Needless to say, you don’t spend on expensive petrol.


*Think about the three main hospitals along this road Sagar Apollo, Jayadeva and Fortis. How many critical patients would have suffered or lost their lives for not reaching the hospitals in time, due to traffic?!
**Study shows that one of the main causes of heart attack among urban dwellers is the stress induced by the traffic.




Saturday, January 14, 2012

A rendezvous with Aurora Borealis

When I was a child I always used to be fascinated with the phenomenon called Aurora, that magnificent light show that nature performs in the latitudes closer to the north and south poles. So when I got a chance to visit Alberta in Canada in 2008, I knew it will be once in a lifetime chance to witness this which we are not privileged to watch in the tropics. But odds were heavily stacked against me to watch this because: 1) It is a rare and unpredictable phenomenon, though more regular during winters, 2) It should be a cloudless, moonless night, 3) we should reach the country side, which is an easy 100KM drive away from the city lights to watch this and hence 4) it should happen on that particular night that we rent a car. But I was optimistic.


Many of our local colleagues in Edmonton discouraged us saying it is a gamble and you have to be extremely lucky to sight it. But having crossed the seven seas to reach Canada, me and two other enthusiastic colleagues, Deepak and Saif, were ready to take the gamble. So we hired a car, drove off into the Alberta prairies on a shivering November Saturday night at 9:30pm. After driving for about 30 minutes, just as we hit Trans Canada Highway 16 away from the city lights, we could see the distinct greenish glow on the horizon that is so typical of the impending display of aurora. Initially we thought it is an illusion as we were so desperate to watch it, but as the glow became stronger we knew that nature was setting the stage for a grand performance. We immediately got off the highway onto to a country road heading north. Great thing about the prairies is that it gives great unhindered view of the skies all the way to the low horizon. So the spots for sky watching are yours for picking.






Pic 1: The distinct greenish glow that appears in the low horizon, a sign of an impending aurora.


After about 15 minutes drive, just as we reached a place far away from all city lights the show began. The auroras appeared about 40 degrees azimuth. We stopped the car, hurriedly setup the tripod and camera at -8 degree Celcius with only light coming from the Camera LCD. Yes, we were ill-equipped to work in the dark that night. Since I did not have a remote shutter release, I had to keep the shutter release pressed for 2 minutes in the freezing cold to get these pictures. It is not easy as after few seconds your fingers will start becoming numb due to the cold and it becomes extremely difficult to keep it pressed.  Later I realized that in the excitement of watching the aurora, I had set my camera at ISO 100. Damn, probably with a higher ISO setting of 800 or 1600 I could have got a sharper image, though grainy.






Pic 2 and 3: Auroras at the peak with Ursa Major overseeing the proceedings.


120 seconds exposure at ISO100, f/3.5 on a Canon 450D 18-55mm Kit Lens.


The show went on for nearly 30 minutes before the aurorae slowly vanished. But we were not satisfied. Got back into the car and waited till midnight, but the aurorae never returned. Looking back at that night, I feel nature was too generous for us. It was as though it was a special show arranged just for these three amigos from the tropic!

What is an Aurora?


An aurora is a natural light display high in the Earth’s atmosphere, caused by energetic particles from the Sun, colliding with the Earth’s magnetic field. This glorious show is called the Aurora Borealis in the Northern hemisphere and Aurora Australis in the Southern hemisphere, but are commonly known as the Northern and Southern lights.

Viewing aurora is incredibly simple, but the conditions need to be right for a display to appear.

Normally you can only see aurora near the poles, such as in Canada, Iceland, and Norway or southern Australia and Antarctica, but when the Sun is highly active, more solar material is thrown in Earth’s direction, creating powerful geomagnetic storms. These storms can bring auroral displays further south to areas such as Southern UK and North to mid latitudes of the USA. The intensity scale is known as the Planetary KP index and basically the higher the KP number the further south Aurorae can be seen, KP 8 or higher can be good for observers further south. To find out what current levels are check spaceweather.com or the Geophysical Institute at the University of Alaska Fairbanks

The best time to spot aurora is around midnight, but this can change depending on viewing conditions and the current intensity of the magnetic storm. Once you are comfortable and your eyes have adjusted to the dark, face north (or south in the Southern Hemisphere). Look low and close to the horizon and look for the faint green/ reddish glow of aurora. It may be quite difficult to see at first, but if it is a powerful display it can be very easy to spot.

There is an aurora alert that has gone out recently due to a high solar activity and a large Sun Spot visible to the naked eye. Those who are in the higher latitudes, this is a great opportunity to watch this grand spectacle.



Pic 4: The real-time view of the range and intensity of the auroras provided by www.spaceweather.com



Pic 5: Aurora intensity scale

Credits

Thank you Andrew Fazekas, a Canadian astronomer, for providing me the timely guidance through email to watch this (his website which has lot of useful real-time details: www.andrewfazekas.com/stargazing/tonight.htm). Also check out his video that graphically explains how auroras form: www.youtube.com/watch?v=x36UcM-aunQ. Details on “What is an Aurora” are borrowed from http://www.universetoday.com/. More details at http://spaceweather.com/



Saturday, July 30, 2011

A game of dice - Part 2: "The dice go missing"

Please read Part 1 before reading this blog: A game of dice - Part 1 

Hope life has been treating you all very well and you were not being subjected to the vagaries of the uncertainty principle and your investments in the stock market have been giving you rich dividends. Things have not been all that predictable for me, as I am still sitting beside the box full of oxygen molecules waiting for all those molecules to move to one half of the box!

In the first part of this article, we looked at the difficulties in predicting the position and speed of a subatomic particle at any given point in time, which has been the basis on which Heisenberg formulated the Uncertainty Principle. We further saw that these contradict the completely predictable macro universe that is governed by Newtonian Physics. So we are yet to find a unified theory that ties the quantum physics (the very small) and the astrophysics (the very large). In this concluding part, let us look at some additional complications in this game of quantum dice.

Have you ever tried leaving your kids alone at home for few hours? What do you expect when you come back home? If your home is exactly the way you left it, you really are one extremely-rare-lucky-parent. I never had any such luck as a parent so far, as invariably I return to a home that has transformed beyond recognition. But then why am I talking about a parental occupational hazard that everyone knows about in an article that is meant for astronomers? Going back to the example of the box full of oxygen molecules, it started off as an ordered state with all molecules neatly tucked away into one half of the box. But when the partition was removed and it spread randomly into the entire box. So we can say that it is less ordered than what it was before. As the time progresses, as the molecules keep moving about randomly, this disorder will only increase. This tendency for any closed system to lose its orderliness and move towards a disorderly system is what is explained by the second law of thermodynamics and the degree of this disorder is known as Entropy. Unlike classical general relativity which is completely predictable, second law of thermodynamics is only almost always true; almost. So those lucky parents with kids who would maintain the homes in perfect order while you are away fall into those categories where the second law of thermodynamics need not be applied. And how fortunate they are!


There is a more simpler way of breaking the second law of thermodynamics than ensuring your kids behave perfectly well while you are away. That is to throw that box full of disorderly oxygen molecules into a black hole. So what happened here? When that box was outside the black hole, the entropy of our “observable” universe was high (to the extent of those misbehaved molecules), because there is no way we can measure anything that happens inside the black holes (as you know nothing can escape from its gravitational clutches). But obviously we cannot do the same with our kids! Even if I have to send them to a boarding school to discipline them, the teachers in the school have to spend lot of energy to make them disciplined and they will be losing that much of ordered energy thus making the universe that much more disordered. So entropy will continue to increase. But then teachers being teachers, how can they break the law of thermodynamics, when they themselves are teaching it!

Stephen Hawking was not comfortable with the idea that the law of thermodynamics breaks down due to black holes. He argued that black hole actually emits radiation so that the law is preserved. This radiation is thus known as Hawking Radiation in honor of his work.

The vacuum that fills the interstellar space is actually not exactly “vacuum”, but it is filled with a pair of opposites: Particle and Antiparticle (also known as virtual particle). An antiparticle has the same mass and spin as the particle, but with opposite charge. For example, electron has positron as its antiparticle. Hawking theorized that when a black hole is nearby, one of the particles in this pair (either particle or anti-particle) may fall into the black hole, leaving the other particle without a partner. In this situation two things can happen: either that other particle also falls into the black hole or it escapes from the hole. To anyone who is observing the black hole, this will look as though the particle is being emitted by the hole.

So if a black hole indeed emits radiation, it must be losing its mass in the process. Which further means there will come a time when it completely runs out of its mass and vanishes from our Universe. So what will happen to all the matter that was sucked into the black hole? Also, in the absence of the particle that fell into the black hole, there is no way we can predict the speed and position of the escaped particle. So according to Hawking “Not only does God definitely play dice, but He sometimes confuses us by throwing them where they can't be seen”. A black hole that emits radiation is a revolutionary idea and it ensured that the second law of thermodynamics is not violated. Which further means, the entropy of our Universe will continue to rise as the Universe expands (what happens if the Universe contracts? Would the entropy starts reducing? Well, let us leave that for a future discussion). In a way entropy is like the fuel price, it can only increase!


I often wonder: Since everything in this universe is made of atoms, including the DNA and the brain cells, even the way we think and behave are governed by the random movements of the subatomic particles? Is it not stupefying to imagine how this random movement of subatomic particles can influence intellectuals to make path breaking discoveries that benefit mankind, leaders to unleash world wars that kill millions, a politician to have a field day of corruption or a terrorist to blow himself up to destroy other fellow living beings? God has strange ways, stranger than the uncertainty principle that we discussed so far. Probably God wanted to make this game of dice more interesting! 

The unification of a theory that governs the very small and the very large seems to be elusive at this stage. The closest attempt to do this has been the formulation of String Theory, though it is still not fully able to address the unification challenges. These are realms of science that are both intriguing and confusing for a far inferior mortal like me. By no stretch of the imagination I am an expert in any of the things that is discussed in this article so far, and my apologies for any errors and omissions. But those experienced parents would agree that it is a lot easier to talk about black holes and the uncertainty principle than making the kids behave in an orderly manner! May better luck be with you in this game of dice, lest you lose it.

-The end-

Friday, July 1, 2011

Who really killed Sankey Trees?

So much has been written about BBMP’s callousness in cutting down 17 hundred-year old trees along the Sankey road, but did BBMP really cut down those trees? No, they did not. They merely reacted to a situation that was caused by you and me. It was our refusal to adjust to the environment we live in, that cut down those trees. It was our hesitation to come out of the comfort of our personal vehicles and take public transport that cut down those trees. We will cause more trees to be cut in the future, as the roads can never be wide enough to support our relentless quest for prosperity and comfort.

Despite the amount of automation I am surrounded with, why am I never seem to be having enough time to do my daily chores? Despite the electronic and mechanical support I have, why am I still late for office? So if I have to make a final dash to the office at the nick of time, so that I do not miss that all important meeting, how can I waste my time waiting for a bus to take me to the office? I now have an excuse to use my personal vehicle, because I live a life that runs on a fast lane, and I never seem to be running fast enough to catch up with it. Not so long ago, my grocery shopping used to be done through a leisurely walk to the nearby corner shop on a lazy Sunday morning. Now I cannot stop my urge to take my car to a far away mall to buy my grocery in the comforts of a climate controlled world that malls offer. I need options to spend the extra savings that I have today, and that often induces a newfound need for me to be more mobile, and I need space. “Give way trees”.

Sankey Tank will never be the same again. The birds would have all flown away. The sun will hit hard on the pavements next summer. There will be no more flowers that will paint the road in different hues throughout the year. Closer to my home I used to enjoy a leisurely stroll along Suranjan Das Road (BEML Road) in the month of May as it was one of the most colourful roads in Bangalore during that time, thanks to the many Gulmohar trees that used to adorn the road in full bloom. Today this road has changed beyond recognition as all those trees have been razed away, to accommodate more IT-Park-bound cars. Elsewhere, the canopy above the Hosur Road from Richmond Road junction to Koramangala has thinned beyond recognition, to make the road wider at the belly, leaving the mouth of the road near Richmond Road as narrow as ever. What are we trying to address here? Were the trees cut to create parking space for the vehicles that wait for the signals to turn green so that they can squeeze ever so slowly past the bottlenecked exit out of this stretch? This is just a manifestation of the lack of planning that this city has been witnessing.

In the developed countries, there are 16 lane highways that are chockablock with vehicles. What does that suggest? Answer is simple: The wider the roads are the more vehicles that are going to pour in to those new-found spaces. So just how much is "wide enough"? Perhaps roads can never be wide enough. We will be cutting down more and more trees, as we need more space to swim the tide of this nation’s economic growth that far outpaces the infrastructure we have to support this growth. No one is going to question our complicity in this crime, because we have a great alibi to this crime: Economic growth.

So can economy and ecology ever coexist peacefully? Why should the trees be sacrificed at the altar of GDP? Can nation’s economic growth be achieved without sacrificing environment? Yes, it can, provided governments have the will and citizens have the inclination to protect nature. Lack of these two is a recipe for disaster. Like other Indian cities an ecological disaster is looming large over Bangalore horizons, unless we act soon.

BMTC has done a tremendous job to introduce Vajra (Volvo) bus service to lure the car-dependent passengers and it has succeeded to a great extent, going by the crowded Vajra buses that we see in Bangalore. As the city continue to grow, more needs to be done to expand this service. Today Vajra service is available mainly along the arterial roads. That is not attracting many potential passengers who are currently hesitant in taking bus, as the service is not available from their door steps. So including residential areas within these bus routes will ensure that most of these passengers will leave their cars at home and take the bus. High rise apartment complexes are only adding to the traffic woes due to the heavy concentration of car-dependent people living in a small land area. BMTC should connect with the builders or the owners of these high rise apartments so that bus services can be introduced linking these buildings. Metro railway is only going to address a small percentage of Bangalore population. Bus service should be improved in tandem with Metro so that there is a holistic solution in place to address the commuting needs of Bangaloreans. Proposed Metro feeder service would be an answer to this if it is implemented wisely.

Why not penalize a car driver if he is found driving along a busy corridor, if the car is not filled to capacity? This will definitely encourage car pooling. Many years ago London introduced the traffic congestion tax on certain busy areas of the city and it required a complex software to detect the traffic movement and charge the car owners accordingly. This software was developed by an Indian software firm. Why cannot we use our software prowess for the benefit of our own societies?

These are some of the questions that we need to answer if we need to prevent more trees being cut down in the name of road widening. So before we blame the authority for being callous, let us ask ourselves. What have we done to improve the traffic situation in Bangalore? As I sit down behind the wheel of my car to make yet another race to improve the GDP, over the graves of the trees that fell along the roadside, I do not even have the privilege to shed few tears. But then I guess a criminal should not ask for such privileges.

Monday, March 7, 2011

Lines and Shades





"Depleted Ozone". My first oil painting on canvas. Circa 1990



"Exploitation". My second oil painting on canvas paper. Circa 1990.

My Idol




R.I.P. Mr.Gandhi
A Scarecrow spotted in Kasturinagar area, often found wandering on the streets of Bangalore looking sky wards










Humorous look at Astronomy and Cosmology



See my blog on "Does God Play Dice" to understand Uncertainty Principle or to get confused (in equal measure)


This cartoon was published in Science Today in Jan 1990.






Sunday, February 27, 2011

A game of dice?


You get up in the morning and see that sun is rising in the east and by the time it sets, the stars will take center stage. In between these two regular celestial shows, you do your daily chores of getting ready for office, negotiating the traffic, working towards achieving the deadlines in your work and finally coming back home to have dinner and a good night’s sleep. The next day is pretty much the same except probably for a holiday that you take, or a business travel that you want to make. While you are busy chasing life (or being chased by life, depending on which end of the chase you are on!) have you ever wondered or marveled at the predictability of this universe? Oh no, I am not talking about how unpredictable various things like stock market, stability of governments, new scams every day, weather patterns, etc., are. In the grand cosmic stage, things are pretty much predictable. Sun will continue to fuse its abundant stock of hydrogen in a 24x7 schedule, to form helium and in the process releasing energy that comes to us as photons, to keep you and me bright and cozy in this cold dark universe. Sun and its trillions of other counterparts are always in business; never take a sick leave or vacation, until they run out of their hydrogen supply.


It is this predictability that prompted Einstein to make that famous quote “God does not play dice with the Universe”. Even before his time the French scientist Pierre Simon Laplace (1749 – 1827) believed that if at one time we knew the positions and speeds of all the particles in the universe, then we could calculate their behavior at any other time, in the past or future. This was his actual quote:


“We may regard the present state of the universe as the effect of its past and the cause of its future. An intellect which at a certain moment would know all forces that set nature in motion, and all positions of all items of which nature is composed, if this intellect were also vast enough to submit these data to analysis, it would embrace in a single formula the movements of the greatest bodies of the universe and those of the tiniest atom; for such an intellect nothing would be uncertain and the future just like the past would be present before its eyes.”


In fact Napoleon, who was ruling France at that time, asked how God fitted into this system, for which Laplace replied saying that he did not have to consider God in this hypothesis. Laplace did not mean that God did not exist, but he thought God does not intervene to break the laws of science that govern this universe. The idea that the state of the universe at one time determines the state at all other times, has been a central tenet of science, ever since Laplace's time.

But the developments in Quantum Mechanics at the turn of 20th century turned this scientific belief on its head. The German physicist, Max Planck, set out solving a paradox that existed till his time. If you heat an object and leave it, it will start emitting radiation in the form of radio waves, infra red, visible light, ultra violet, x-rays, and gamma rays, all at the same rate. This means the entire universe should be of the same temperature at any given time, but as you know that is not the case. If all hot bodies started emitting x-rays and ultra violet rays, then this world could not have harbored life due to harmful radiations from these rays. Planck suggested that the radiation emitted by a hot body is in the form of packets or quanta of a certain size. He further postulated that the quantum of energy in these packets is larger for x-rays and ultra violet rays compared to infra red rays and visible light. Which further means the quanta varies for different forms of radiations. So unless the hot body is super massive like a star, it cannot have enough quanta for x-rays and ultra violet rays to harm us. So you could still hold that hot cup of coffee on a Sunday morning during monsoon, without getting cooked by the harmful radiation.

Few years later another German physicist Werner Heisenberg unearthed another paradox that came to be known as the Uncertainty Principle. It states that the position and velocity of a subatomic particle cannot both be measured, exactly, at the same time (actually pairs of position, energy and time). To see where a particle is, one has to shine light on it. But by Planck's work, one has to use at least one quantum of light to do this. This will disturb the particle due to the energy released by that quantum of light, and change its speed in a way that we cannot predict. To measure the position of the particle accurately, you will have to use light of short wave length, like ultra violet, x-rays, or gamma rays. But again, by Planck's work, quanta of these forms of light have higher energies than those of visible light. So they will disturb the speed of the particle more. It is a no win situation: the more accurately you try to measure the position of the particle, the less accurately you can know the speed, and vice versa. This is known as Heisenberg’s Uncertainty Principle. This was a complete contradiction to Laplace’s scientific determinism. Einstein was not comfortable with this apparent randomness that this principle will introduce to the cosmos, which prompted him to say that the God does not play dice.


To explain this further, assume you have a box with a partition in between. Assume further that one half of this box is containing oxygen molecules and the other half is vacuum. If we remove the partition the oxygen molecules will start spreading the entire box randomly filling it completely. Applying uncertainty principle we can actually apply a probability that all molecules due to their random movement can actually travel to one half of the box so as to leave the other half as vacuum just the way it did exist when the partition was in place. Possible? Yes, though with an extremely low probability. Therefore this is more like playing dice. So god does play dice with the universe at a micro level!


So all these completely contradict the working of the universe that is largely governed by the Newtonian Physics. Scientists are yet to find a theory that unifies quantum mechanics and astrophysics. In the second and concluding part of this article we will look at the role black holes play to make the uncertainty principle more uncertain. In the meantime, you could continue to invest in that attractive stock, hoping that it will yield a handsome dividend tomorrow!


-To be concluded-