Tuesday, February 27, 2007

Good TV

At the moment I am mostly watching

Anthony Bourdain: No Reservations
Top Gear
Charlie Brooker's Screen Wipe
West Wing Season 2

PhD Viva

Three weeks today.

Saturday, February 24, 2007

Rolling News Low Point

Last night a train derailed and slid down a steep embankment. I am a regular Virgin trains user and the experience must have been harrowing. Something happened last night on BBC News 24 that made me feel numb.

A BBC employee/reporter happened to be travelling in one of the coaches and she phoned in to give a live report from inside one of the stricken coaches. Around her we could hear the sounds of windows being broken as people made their exit and screams and shouts from hurt/scared passengers. She sounded most pleased with herself to be in such a career enhacing position.

Put yourself in that situation. As people are trying to evacuate a stricken train and help others to escape your first though is to phone your boss and enhance your career prospects. Why not get out of the train and help everyone else out and then do everything you can to look after injured people outside the train first? Then think about handing over an eyewitness report. These were tasteless and selfish first instincts.

Friday, February 23, 2007

Colours of nature (part 2)

The other major colours you see in nature are green from foliage and blue for water. The sea looks blue because it reflects the sky. Water itself is transparent. Small depths of water look transparent (like a bathfull) but if you look through enough water (like when you are underwater and can see a long way) things look blue because there are so many water molecules that they absorb most of the colours completely. The only colours that can can more than about 20 metres are blue and a bit of green - that's why things underwater seem blue-green. From land the sea looks blue because it reflects the sky. So when the sky is grey the sea looks grey.


Plants are green because they absorb all colours except green. They break up water and carbon dioxide molecules and fit them together to make oxygen and sugars. They do this using a molecule called chlorophyll. If you give a chlorophyll molecule just the right amount of energy it will give you an electron. This 'just right' energy just happens to be the same energy of a blue particle of light. You can also get an electron if you give it a red light particle. This will have a different energy to a blue light particle but it turns out that this energy is also just right to get another electron from a different part of the structure. When chlorophyll has all these electrons loose they get passed around between loads of chlorophyll molecules until eventually they hit water and carbon dioxide molecules and help them to break down and reform into sugars. So blue and red light get absorbed by chlorophyll and green gets scattered back - green particles don't have the right energy to release an electron. That's why plants are green. Not all plants use light to make food. Funghi and mushrooms decompose dead or living tissue to make food. They often grow in fields or woods where little animals die and rot or the leaves and bark from trees rot. They don't need light and are rarely green.

Thursday, February 22, 2007

Rover and Scientific Research

£270m of taxpayers money was used to prop up the ailing Rover car manufacturing company, which is now Chinese owned. As a result £68m given to the scientific research councils by the DTI will now be taken back to help balance the books. This means that thousands of research grants will be turned down and thousands of PhD and Postdoc projects across all scientific disciplines will never come into being. The worst hit research council is the Engineering and Physical Sciences Research Council (EPSRC) which loses £29m.

Science is the biggest thing in history. It has had a bigger impact than any king, politician, war, disease, political ideology or natural disaster. The changes in the world over the past 100 years have been science driven. Computers, TVs, mobile phones, space flight, electric lighting and much more have come directly from Physics. Hacking away at scientific research budgets in this country will cause it to fall behind. And it may prevent the spark of inspiration that will help find a cure for aids or cancer, develop the electric car or make clean nuclear fusion energy a realistic prospect.

Wednesday, February 21, 2007

Road Pricing e-petition

I am one of the 1.5 million people who has signed an online petition on the Downing Street website to ask the government to scrap plans for road pricing and road tracking. This morning I received a response e-mail from 'Tony Blair' which pretty much said that nothing had been decided and options were being checked but pilot schemes are going ahead and some form of congestion charging will have to be introduced. So the will of 1.5m voters and tax payers is to be ignored. Add these people to the list of attendees at the anti war marches a few years ago. Or the people who campaigned against the poll tax. This is not a republic; we don't elect people to make decisions on our behalf we elect them to enact our will. Democracy does not work in this country at the moment. But the masses are busy with their 'lifestyle'. No October revolution here.

The simple fact is that people have no choice; no-one willingly sits in traffic for tens of hours per week. House prices in this country prohibit many people from living close to where they work. The nature of the job market in this country also means at least one person per household has to travel. Give me a tax break to buy a house near to where I work and force the employers of my partner to let her work from home 3 days a week and that will cut four lengthy and 'unnecessary' journeys per day. But don't charge me to use the roads at peak times. I already pay to use them. Paying to congest the roads will not prevent congestion.

Tuesday, February 20, 2007

Mondrian

Piet Mondrian was a Dutch artist who contributed towards the De Stijl movement. He is most famous for his non-representational paintings and many examples are to be found on posters in student lodgings.

For some reason his early naturalist paintings have a deep effect on me when I look at them. Especially the two shown below. I think that for a long time I have been deep in the woods and now I can just start to see familiar things between the trees. Maybe. Or it could be that these are tremendously atmospheric paintings done by a genius in an early stage of his career.

Monday, February 19, 2007

Energy usage

I was given a gadget that will measure the energy use of my electrical appliances and help work out their monetary costs

Kettle 2890 W
Computer 130 W
Toaster 1010 W
Phone charger 0.002 W
Dishwasher 600 W
Big TV 110 W
Small TV 42 W (21 W standby)

Which means that £1 ($1.90) gets me

178 cups of tea (2 cups per boil, 800 ml water)
80 hours computer time
255 slices toasted bread
32000 charges of my phone
9 dishwasher loads (2 hrs per load)
100 hrs big TV
250 hrs small TV

I started a new job today.

Friday, February 16, 2007

Less Is More

A Quaker had this sign put up on a vacant piece of land next to his home: THIS LAND WILL BE GIVEN TO ANYONE WHO IS TRULY SATISFIED.

A wealthy farmer who was riding by stopped to read the sign and said to himself, "Since our friend the Quaker is so ready to part with this plot, I might as well claim it before someone else does. I am a rich man and have all I need, so I certainly qualify."

With that he went up to the door and explained what he was there for. "And are you truly satisfied?" the Quaker asked.

"I am indeed, for I have everything I need."

"Friend," said the Quaker, "if you are satisfied, what do you want the land for?"

And From Zen

There was once a stone cutter who was dissatisfied with himself and with his position in life.

One day he passed a wealthy merchant's house. Through the open gateway, he saw many fine possessions and important visitors. "How powerful that merchant must be!" thought the stone cutter. He became very envious and wished that he could be like the merchant.

To his great surprise, he suddenly became the merchant, enjoying more luxuries and power than he had ever imagined, but envied and detested by those less wealthy than himself. Soon a high official passed by, carried in a sedan chair, accompanied by attendants and escorted by soldiers beating gongs. Everyone, no matter how wealthy, had to bow low before the procession. "How powerful that official is!" he thought. "I wish that I could be a high official!"

Then he became the high official, carried everywhere in his embroidered sedan chair, feared and hated by the people all around. It was a hot summer day, so the official felt very uncomfortable in the sticky sedan chair. He looked up at the sun. It shone proudly in the sky, unaffected by his presence. "How powerful the sun is!" he thought. "I wish that I could be the sun!"

Then he became the sun, shining fiercely down on everyone, scorching the fields, cursed by the farmers and laborers. But a huge black cloud moved between him and the earth, so that his light could no longer shine on everything below. "How powerful that storm cloud is!" he thought. "I wish that I could be a cloud!"

Then he became the cloud, flooding the fields and villages, shouted at by everyone. But soon he found that he was being pushed away by some great force, and realized that it was the wind. "How powerful it is!" he thought. "I wish that I could be the wind!"

Then he became the wind, blowing tiles off the roofs of houses, uprooting trees, feared and hated by all below him. But after a while, he ran up against something that would not move, no matter how forcefully he blew against it - a huge, towering rock. "How powerful that rock is!" he thought. "I wish that I could be a rock!"

Then he became the rock, more powerful than anything else on earth. But as he stood there, he heard the sound of a hammer pounding a chisel into the hard surface, and felt himself being changed. "What could be more powerful than I, the rock?" he thought.

He looked down and saw far below him the figure of a stone cutter.

Thursday, February 15, 2007

Tchaikovsky

In 1879 a large pro-slavic sentiment had built up in Russia after Turkish troops attacked and killed many innocent people in Serbia. A Red Cross benefit concert was arranged to help Russians who had volunteered to help in the resulting Serbo/Turkish war alongside their fellow Slavs. PT agreed to compose a piece for this. In it he referenced Serbian and Russian folk songs and anthems. It starts with a slow mournful marching rhythm which suggests a funeral procession which later becomes a war march as Russian and Serbian troops march to eke revenge. It is unclear how much of this was just hack work for PT, how strongly he felt about the issue and how much he relied on emotions from his personal life. He would only say that he felt the performance at the concert to be a great success.

Such nationalistic and vengeful concerns aside this is a great ten minute piece of work. In terms of orchestral music this would, at the time, have been pop music. In overall classical music terms it is heavy metal. It sits naturally alongside the 1812 Overture (which is even heavier since it contains cannon blasts). Much has been said (and not said) about the man and his work. Tchaikovsky afficionados tend to see these two pieces as too overt and vulgar. I find them exciting and I'm not prepared to be sniffy about the bombast, bluster and bravado. If PT was playing to the crowd then so what, it works. Here is an out of copyright version, for those interested.

Wednesday, February 14, 2007

Where's the Beef?

Many of you may be familiar with the phrase 'Where's The Beef?' without knowing where it is from. It comes from a 1984 advert for Wendy's, a US burger chain. It was subsequently adopted (even by politicians) as a means of questioning the substance of something and passed into slang.

Tuesday, February 13, 2007

Why is the sky blue?

Light particles come in all different colours and what that really means is that each different colour of particle has a slightly different energy. Red light is less energetic than green light which is less energetic than blue light and so on. If you go into space the sky is black and all the stars (including the sun) are white because the light particles they emit come in every different colour and when your eye averages them you see white. The light that they send out does not hit anything on its way to reach you because space is empty.

Down here on the earth we have tonnes of atmosphere between us and the sun. The white light comes in and most of it gets through. Except the blue light. That has a slightly higher energy than the rest and that makes it much more likely that when it hits an air molecule it'll get scattered. All this means that when you look at the sun it looks white MINUS the blue that has been scattered out - this means it looks yellowish. When you look elsewhere in the sky it is blue because the blue light gets scattered around everywhere and it hits your eyes from all directions at once.

Another interesting effect happens when you look near the horizon (when the sun isn't near it)- the sky looks paler here (whiter and not as bright). This is because blue light that goes near to the horizon and then back to your eye has to travel a long way. Chances are it'll get scattered again some other way. So from the horizon some of the blue light is taken out and the sky looks less of a deep blue and paler. When the sun is near the horizon it shines straight at you through more air than if it was above you and all the blue light scatters out so the sky is yellow during sunset. Dust and pollution in the air can take some of the green out too so that the sky becomes red. The same thing happens in the morning - shepherds warning! If you stand on Mars and look up the sky it should be blue but it is always red because there's so much dust in the air.

Clouds are different. They are made up of water and this scatters all colours of light the same. Any colour of light that goes into a cloud gets scattered in any direction so when you look at a cloud you see all the colours at once and it seems white to your eyes. Water weakly absorbs light so clouds don't appear brilliant white - they are a bit dimmer. Big wet stormclouds have more water in them and they absorb more light so they seem darker and greyer. Clouds are also very big and block out a lot of light from hitting their sides or their underbelly. When water freezes it doesn't absorb light very well. It transmits it or reflects it. Snow is white because it reflects all colours evenly and it doesn't absorb much light.

The colour of the moon is white. It reflects a bit of each colour of the light from the sun that hits it down to us. A bit of the blue can get scattered and make the moon yellow. Sometimes particles get into the air that scatter the red light very well and the light from the moon has all its red light taken out and it looks blue - a blue moon. It's a very rare occurence because to get these chemicals into the air you need a forest fire or a volcano. This effect never makes the sun seem blue because the sun is so bright - there is never enough of the chemical in the sky to remove enough of the red light.

Sunday, February 11, 2007

Microsoft vs The Beatles

I have nothing against Microsoft (MS) as a software company. Windows works. It has flaws; over rigidity, security vulnerablities and instabilities but the typical PC user finds the interface with their hardware quick and easy. Linux does not offer the same level of support to its users. A Linux installation can take weeks to finalise. In the past I have been plagued by problems with such basics as getting my computer to play sound and obtaining drivers for my broadband modem.

I do object to the business practices of MS. The consumer did not choose Windows, because it is bundled with all new PCs. The situation is akin to that of a person baptised as an infant and raised as a Christian; all of this was decided for them without their consent. After decades of Windows ubiquity anyone who considers heresy must repel years of familiarity, habit and dogma.

A recent example is the smear campaign of The Beatles begun by MS. The Beatles back catalogue is to be made available online via software from Apple. Such a lucrative contract for the only significant commercial rival to MS has prompted them to lash out. Cue an article on the MS network website. It suggests that The Beatles are not above criticism and that there are deficits in some of their output and their personal behaviour. Fair enough. The article also suggests that The Beatles were not innovators and merely followed the tide. The Beatles have admitted that they borrowed mercilessly and there is no shame in this because 99.99% of all art works in this way. But The Beatles did innovate and lead the way at certain points. The article says that The Beatles were slow to emerge from psychedelia and that the song 'Get Back' marks their return to straight rock, hence the name. Wrong. The title of 'Get Back' reflected the desire of Paul to resume live performance. The real get back record was 'Lady Madonna' recorded in early 1968 before The Beatles went to India, a full year before 'Get Back'. The Beatles abandoned psychedelia at its peak and were one of the first mainstream groups to get back.

Factual innaccuracy renders any just criticism in the MS network article into a smear campaign penned by a lazy journalist with a hidden commercial agenda. Perhaps MS can explain on their mouthpiece website why MS Vista costs twice as much in Britain as in the US. Bill Gates gave a non answer the other day. The real reason is that the British consumer has been exploited by high prices for many years. The British economy is founded upon the idea that its own health is more important than that of the individual. This sort of ideology, in which the state is deemed more important than the individual is inherently totalitarian. Consumer debt is caused by excessive prices in all sectors. The banks then move in and pick the bones of the carcass by charging overdraft and credit card fees. Of course, the consumer has choice - no one forces the consumer to pay these prices. Yeah right. And billion dollar ad campaigns don't work in convincing people that they need this product and will fall behind and face social exclusion if they don't get it.

Saturday, February 10, 2007

The Energy Balance

For a 200lb (14st or 90kg) person the energy burned per hour in kcal on the following activities is

Sleeping 82
Standing 106
Walking (3 mph) 388
Driving 3 *
Billiards 223
Housework 259
Sex (missionary) 376
Swimming 541
Cycling 350
Playing football 894
* not counting background calorie loss

Compare this with the calories in some foods

McD quarter pounder 500
McD fries 224
Pint coke 420
Dominoes Pizza (12") >2000
Pint beer 180
Glass Red Wine 80
Cup tea (milk & sugar) 30
1 chocolate digestive 90
1 mouthful donner kebab 42

So if you walk for about 3 hours each way to fetch your pizza you'll have earned it.

Thursday, February 08, 2007

Weather forecasts; BBC vs Five

The BBC introduced a new graphics format for weather forecasts in 2005. The brightness of the map indicates cloud cover and temperature which means that most of the time the UK is a horrible sludge brown colour. The map was angled which made Northern England and Scotland disproportionatly small. This was supposedly to resemble the curvature of the earth but the effect suggested that the country should be viewed from the south and that the north was 'up there' somewhere ie away from 'us'. To rectify this the BBC decided to extend the length of time spent doing their 'flyby'. At a given time of day we visit each part of the country to see what the weather is like. This is highly bewildering and I soon switch off, especially during some of the more needlessly elaborate forecasts.

It should be simple. Map of UK, short summary, then talk about rain, wind, temperature, hours of light and any other relevant details. 'It will be mild tomorrow with a band of rain moving from the southwest across the country during the day'. Keeping an eye on a clock in the bottom corner could help me to figure out when the rain will hit me. The old system that the BBC used was great and they did the best forecast on TV, with isobars and everything. The new system claims an accuracy for itself that it does not possess and as a communication tool that relies on clear graphics it is fundamentally flawed. If you would like to complain then e-mail them.

The other TV channels attempt a weather forecast but I don't have much more to say about any of them except Channel 5, who do the best forecast on TV at the moment. Quick, simple and memorable, it does not indulge itself in a virtual, time accurate flyby of a brown bit of land. Five are also currently producing excellent kids TV and by showing the best of American TV they are providing quality TV in a cost effective manner. And Megastructures is one of my favourite shows.

Tuesday, February 06, 2007

You'll Never Walk Alone (pending good dividends)

Two american investors has just spent about £500 ($800 million) on Liverpool FC. When this club was established in 1892 six states were still to be admitted to the union with another six states having been added shortly before in 1889/1890. Grover Cleveland was elected President in the election of 1892. The Indians were still putting up a fight; the massacre at Wounded Knee was in 1890. The first US movie was made in 1889. In Britain Gladstone was elected Prime Minister and Arthur Conan Doyle published 'The Adventures of Sherlock Holmes'. Given the history of this football team the new owners Gillett and Hicks have pledged to respect the history of, and I quote, "the franchise".


Some facts about the new owners. David Gillet has made his money out of processed meat and ski resorts. He was declared bankrupt in the early 1990s but has since bounced back. Tom Hicks made his money from venture capital, investment firms and soft drinks. He also donated money to Ann Richards, the Governor of Texas, in the early 1990s but shifted his donations to George W. Bush when Ann Richards lost an election in 1994. Hicks has since become the number 4 career patron of Bush during his career. In 1998, Hicks made Bush a multi-millionaire by buying a Texas baseball team from a consortium headed by Bush.

The new owners have expressed an interest in selling the name of the new stadium to an advertiser "If the naming rights are worth one great player a year in transfer spending, we will certainly look at that as a serious option." Yeah, right. The name of the old stadium, 'Anfield', conjures up rich images of football heritage and success whereas modern 'branded' football stadiums have names like 'kit-kat crescent' which conjures up images of over-sugary chocolate bars mass produced in factory production lines staffed by workers on low wages in York whose jobs have been taken away and moved abroad where the cheaper workers are.

On the news tonight a Liverpool fan was heard to mutter that he preferred the club to be in American hands rather than the club be owned by the consortium from Dubai who recently expressed an interest. He never explained why. Maybe the fact that the Americans are white makes it OK that they are running a club in the hope of gaining "on-the-pitch success and economic success". The latter is the prime reason for investing in top-flight English football. They definitely don't know anything about football judging by the comment "this is the most important club in the most important sport in the world".

Monday, February 05, 2007

Epic tome

My fiancee insists that she does not take a long time to get ready in a morning. I admit, she is not an especially vain lady but in an effort to convince her of the cumulative time I have adopted a weapon; a one thousand page biography of Winston Churchill. I have been chipping away at this book, a few pages at a time, whilst she does her hair and makeup. I'm making good progress. The other day I managed to get all the way through the Tehran conference in one sitting. Anyway, the book is excellent, my time is being well spent and my lady can take her time to prepare for the day ahead.

New series of Charlie Brooker's Screen Wipe starts tonight BBC4 at 10pm.

Friday, February 02, 2007

Oil company profits are not the problem

Shell has just announced a record profit of $25bn. The knee-jerk reaction to this is to gasp and ask how they dare rip us off. In fact, oil companies make very little money at the petrol pumps.

Cost of a barrel of oil (159 litres) - £ 42
Petol yield per barrell 51.4% - 82 litres
Net earning at the pump per barrel of oil - £ 74 *
Estimated profit for oil company - 1.5p per litre (£2.39 or $4 per barrel)

The price of petrol is mostly comprised of >50% tax charged by the government. The oil companies make most of their money in the speculative and dangerous business of extracting the oil from the ground.

So where do the oil companies spend their profits? A small percentage of the profit goes into shareholder dividends and bonuses for employees. Most of the money is invested back into infrastructure and finding new oil reserves.

The profit margins aren't all that big either. To work this out divide net income by total revenue. This will give an indicator of the fraction of earnings that are lost due to costs and taxes. The graph below shows how the profit margin of the energy industry compares with other businesses
Banking comes out top. Banks do provide a useful service but there is a dark side. How many people have been charged a fine because bills have been deducted from their bank account before their cheques have been paid in? If this does happen don't let them get away with it. In most cases the charges can be appealed quite easily. Go to your local citizens advice office. They are experienced in dealing with cases such as this and will help you draft letters that will get your money back. It works, trust me.

Anyway, the knee-jerk reaction to oil company profits should be avoided. Get onto the chancellor about the price of petrol. The real problem with the oil industry is in the environmental damage caused by its day-to-day procedures and by accidents and, of course, by the contribution to global warming. Oil companies do not pay for the oil they take from waters owned by the UK. They pay for a license to operate but what they extract they keep. It all amounts to subsidy. And I haven't mentioned the practices used by oil companies to destabilise oil rich regions. The behaviour of oil companies in countries such as Nigeria is a whole other can of worms which you can open here.

Thursday, February 01, 2007

Lord Levy of Royston Vasey



"This is a local House of Lords. For Labour party donors."

Coffee

Coffee is the second most popular drink (after water) and the second most traded commodity (after oil). There are about 70 species of plant in the genus Coffea but 2/3 of commercially produced coffee comes from the arabica plant because of the superior taste and quality. The remaining 1/3 is mostly from the robusta plant which produces a more harsh flavour with a higher caffeine content. The arabica bush is about 1.5-2 metres tall and it grows in temperate climates. It is very sensitive to its environment and grows best at altitude in soil with low acidity. The plant is native to the highlands of Ethiopia, grows for about 50-100 years and starts to produce fruit after 4 years. The fruit resembles red berries and inside there is a small seed or bean.


The chemicals that give coffee flavour are all introduced during the growth process and nothing can be done to the beans once they have been grown. Coffee cultivation is difficult and involves many variables such as plant genes, soil, rainfall, sunlight and temperature ranges. Coffee is grown in over 70 countries principally Brazil, Colombia, Vietnam, Indonesia, Costa Rica, Mexico, India, and Puerto Rico. Human taste and smell are so sensitive (they evolved to protect us from bad and rotten food) that a single bad coffee bean in a batch of 50 ground to make a cup of espresso will taint the flavour. For this reason the best coffee producers employ workers to hand pick healthy ripe fruits. Coffee pickers can each pick 50-100kg of coffee fruits per day. The coffee cherries are dried and a machine is used to extract the raw green coffee beans. Any beans that are mouldy or defective are removed.

The next step is roasting in which the beans are heated to about 200 degrees C for between two and forty minutes. This drives a series of complex chemical reactions inside the bean that enrich the flavour. Green beans are mostly made of sugars with acids, fats, minerals, caffeine, proteins and amino acids making up the remaining 1/3. The cell wall of coffee beans is very thick and remains intact during roasting. Green beans have a 10% water content which is reduced to 5% during roasting. This water turns to steam and the inside of a bean is like a pressure cooker in which the sugars react with fats, amino acids and proteins to make melanoidins and glycosylamine which are brownish, bittersweet chemicals that give roast coffee its dominant taste. So the roasting process is essentially a caramelisation process. Alongside this a series of volatile, low mass aromatic compunds emerge that give coffee its familiar smell. If the beans are not roasted for long enough the aromas do not emerge and the coffee tastes acidic. Poor quality beans are roasted for longer periods to drive out the poor smells and tastes. This leaves a tasteless, bitter bean. The accepted roasting time for good quality beans is 12 minutes. Instant coffee is made using the leftover, crap beans by dry roasting them. The taste is bitter and there are often all sorts of unwanted products from the harvest thrown in to bulk it up.

Once the coffee is ground it is ready to be brewed. There are many techniques. The coffee can be placed in a filter and have hot water percolated through it over about 5 minutes. It can be placed in a container with the coffee for 5 minutes and then a plunger can be used to strain out the grounds as the liquid is poured out. These two methods allow more caffeine to be extracted but they also result in the dissolution of more of the soluble acids. The espresso techinque is favoured by connoisseurs. Here the grounds are compacted to a dense, fine powder. Hot compressed water is squirted through for about 30 seconds. A thin layer of dense, foamy liquor or crema forms on the surface of the coffee in the cup. If this is too light in colour then the extraction time was probably too short, the grounds too coarse or the water was not hot enough. A dark crema with a hole in the middle signifies over fine grounds in too great a quantity. Overextracted espresso gives a white spot in the center of the cup if the brewing time was too long or a white froth with large bubbles if the water was too hot.

The final result is a colloid of gas bubbles, oil droplets and solid fragments less than a few microns in size with water molecules bound to them. The coffee fluid has lots of body and it is very viscous. It coats the tongue with emulsified oils that sit there for about 20 minutes and continue to release flavours and aromas. A good cup of coffee should stay with you for about a quarter of an hour after the cup is empty.