CFL vs HPS penetration

tusseltussel

tusseltussel

Well-Known Member
TeaTreeOil said:
Light does add up. It'd unlikely double(theoretically it is under the right conditions), but it gets very close(reality). Red spot light + blue spotlight + green spotlight makes a white spotlight.

Two speakers are louder than one. Waves add to each other. It's called resonance.

If two lights are the same distance from a plane. Calculate the intensity based on I = lm(total) / feet(distance) ^ 2.

Here, look, two spotlights overlap. Brighter. Take a mirror. Reflect some light off it onto the wall. It gets brighter!

Click to expand...
ok so all your cfls have to be 2-4 inches away from one another for them to add up because thats about the max penetration they have... they dnt add up in the aplication of growing weed

until one radio is louder than the other you wont be able to here it its the resonance you here not the volume its like surround sound more spekers sounds louder but its not its just the placment of them
 
TeaTreeOil

TeaTreeOil

Well-Known Member
Two waves from pretty much the same source over lap(peaks add, valleys add). If you've studied home entertainment systems you'll know all about proper placement to gets the waves to achieve this optimally. EDIT: Got a better one. A chorus/choir. Why are dozens of people, in unison, loud enough to be heard throughout a stadium or hall, but not one alone(without a microphone and speakers)?

Here's a graph from my thread about CFLs: https://www.rollitup.org/2234594-post168.html

Two 26w add up to 2000 lumens over a foot away from the same point.

Those same two bulbs both about 6" from the same point add up to nearly 13,000 lumens. Four bulbs @ 6" distance from a point and that's nearly 26k lm.
 
9

9inch bigbud

Well-Known Member
TeaTreeOil said:
Light does add up. It'd unlikely double(theoretically it is under the right conditions), but it gets very close(reality). Red spot light + blue spotlight + green spotlight makes a white spotlight.

Two speakers are louder than one. Waves add to each other. It's called resonance.

If two lights are the same distance from a plane. Calculate the intensity based on I = lm(total) / feet(distance) ^ 2.

Here, look, two spotlights overlap. Brighter. Take a mirror. Reflect some light off it onto the wall. It gets brighter!

Click to expand...
Two speakers are louder than one. Waves add to each other. It's called resonance
Click to expand...
the sound in the same room may not be noticeable but if you had the radio outside and only had 1 speaker then i.e you walk 50M and then you dont hear anything at 50m then you put the other peaker on you will hear it im not sure it will make the sound carry another 50m=100m it will carry it a bit more but how much i dont know? when it comes to sound the more watts you use the further the sound will carry even though it may not sound any louder.

i.e if you stood at the front of a rock concert you would be deff the watts from the speaker do not make the sound much louder than i.e a 500w amplifier if you add a 2000w amp it makes it heard over a further distance from the stage not much louder. you will feel the beat/sound going through you the closer you stand to the stage but you dont notice the sound much louder than if you stood ferther away.
 
TeaTreeOil

TeaTreeOil

Well-Known Member
Sound requires a medium to travel. There is no sound in space. It has a much slower speed than light(@770 MPH). Light is radiation which travels through vacuums. Radiation is a wave-particle(duality). Sound also decays in an inverse square, though.

Twice the volume(of the music) does not mean twice the area(or 3D volume) covered. It means 2 times within the same area.

As
Intensity = Power / Area
applies to light, so does it apply to sound, and all waves.

This thread is not about sound, though.
 
AeroKing

AeroKing

Well-Known Member
Wow, great discussion going on here!

I have a couple things I'd like to add.

Light differs from sound. Sound is a wave that effects matter. When two sound waves hit 1 particle, both waves will effect it.
Light moves through space. When 2 lightwaves hit each other, they do not have the same "added affect" as a sound wave.

So, light pressure is different than sound.

Ok , now we've all heard this before: "Lumens do not add up", "Watts do not add up" or "Lights do not add up".
However, if you center a lux meter at a set point and turn lights on one at a time around it, the reading will rise.

Here's where it gets interesting:
If you take a measurement from 1000 watts of CFL at say 6", you'll get a high reading. You'll keep this high reading all throughout the "coverage area" that the lights are covering.
If you do this with a 1000w HPS, you'll get a much higher reading, but as you move from side-to-side along the "coverage area", It will drop.
(Since in gardening, we generally work on a flat plane, the "coverage area" will be regarded as a flat plane.)

So, we establish that a single stronger source of light will produce a higher lumen at a set distance, but an uneven pattern that tapers from this single source. Many smaller sources of light will not ever produce a higher measurement than the single source, but they will evenly blanket an area with light.

Now, let's move the other way, up and down.

Let's say you take an HPS bulb rated at 160000 lumens. At one foot, you'll read about 160k lumens. At two feet, you'll read a 1/4 of that. This is called the inverse square law. Because light radiates evenly, at double the distance, you quadruple the area that the light is now covering. (Imagine the surface area of a balloon that's 1/2way blown up vs. one that's completely blown up - Light spreads in the same way the balloon does)

So, (for our example), at 2' you have about 40k lumens. At 3', You'll have 10k, 4' = 2500 lumens...

Ok, so that's penetration. At 4' away from the light, you still have a usable amount of light (2500 lumens) that will support growth.

Now, let's try that with many smaller points of light.

Let's say you use 42 w CFLs rated at 2700 lumens.
So at 1', let's say you have so many, so close that you are recieving a total measurement of 10000 lumens - not bad right? Especially since you're getting the same amount of light that you' be getting at 3' with the HPS.

Now here's the problem: Each of these smaller sources are suseptible to their own inverse square law.
So, You can't just divide the 10000 by 4 to get 2500 at 2'. You would need to take each of the 2700 lumen sources and start quartering those. So now, you've gone from many sources adding 2700 or less to the measurement, to many sources adding 700 or less. Bulbs that are further away, now have little to no effect and the ones that are close, can't get their light far enough to really bring that number up.

Whether the source is from an HID, CFL, or LED, this rule holds true.
If a 200w CFL has a higher initial lumen than a 150w HPS, the CFL will have better penetration than the HPS.

if you want proof, google "inverse square law". This explains it all...
 
TeaTreeOil

TeaTreeOil

Well-Known Member
Whether the inverse square law applies to them individually is the same as it applying on the whole.

Whether you take i = 10000 lm / 2 ^ 2
i1 = 2500

Take another light source, and the same equation as above is true.

i2 = 2500

But I was already at 2500!! What would be the total intensity? i1 + i2! Of course. If it's zero it becomes 2500. Why is this (addition) so difficult?

Lets take this as a 'complex' problem and solve it at once!

We have a total of 20000 lumens. Both 2 feet from the target measuring point.

i = 20000 lm / 2 ft ^ 2
i = 20000 / 4 ft
i = 5000 lm/ft

What do yall not understand?
 
9

9inch bigbud

Well-Known Member
TeaTreeOil said:
Sound requires a medium to travel. There is no sound in space. It has a much slower speed than light(@770 MPH). Light is radiation which travels through vacuums. Radiation is a wave-particle(duality). Sound also decays in an inverse square, though.

Twice the volume(of the music) does not mean twice the area(or 3D volume) covered. It means 2 times within the same area.

As
Intensity = Power / Area
applies to light, so does it apply to sound, and all waves.

This thread is not about sound, though.
Click to expand...
im not disagreeing with you. what i am saying is watt for watt CFL's are hotter than a HPS if you have a closed room and add a 1000w of HPS and a 1000w of CFL the room temperature will be hotter in the CFL room there will be more heat because of more cable to connect all the 23 watt lamps up together will get warm we are talking 23w CFL's they are self ballast and get hot as well as the heat coming from the light its self.

back to my origianl post about false economy by thinking you can get away with out an extractor fan.

all this talk about fan size and if i use CFL i will not need to use a fan ect.. air exchange is just as important as the light you use so using a bigger fan will help no matter what light you use! the fan shoud exchange the air in the room at least 30 x per every hour for a good growing environment no matter where what you grow under you should use a fan the more air that is is exchanged the better your plants will do.

did you know that using watt for watt CFL is hotter than HPS? lets say we have a room each room as 150w of power being used 1 room is CFL the other HPS that with out the air being exchanged the CFL room would run hotter than the HPS although you can get the CFL closer to the plants does not mean they dont give off less heat the differance is the heat comes from more points rather that a single point, if you had a closed room the 150w of CFL would be hotter than the 150w HPS.

The HPS has a ballast that can be placed outside the room cutting down on heat being made. the CFL's have built in ballast even though they are small they still get hot so you dont just get the heat from the light being made you get the heat from the small ballast that all CFL light use to ignite the bulbs adding extra heat in the grow room.

by cutting down or not using an extractor fan that does not exchange the air at least 30x per hour to save power is false economy! think of it as adding Co2 to your grow room the more times the air is exchanged the more Co2 the plants get without Co2 in the air plants can not grow you may get away with out using a fan, but you are lossing out on more bud if you dont use one! no matter what light you use + 150w of HPS is a lot easyer to cool than 150w of CFL you try filtting a cool tube over 7 x 23 CFL lights and if you stick the HPS in the cool tube you can get the light just as close as a 23w CFL. work it out if you are stuck to a very small space the 150W HPs will run cooler if you used a cool tube in fact you could let the plant grow round the cool tube they will not burn if a leaf would touch a CFL it would burn.

no air exchange is to bring/ keep the Co2 at the maximum in the room if you grow as some do in closed tight boxes the Co2 is used up and the plants will die the air is exhanged to keep the enviroment perfect for growing. if you do not extract air from the room the humidity would rise the heat would rise and Co2 would be used up in very short time. i cant think now off the top of my head how much carbon (co2) is needed to produce a tone of vegetable matter i think its a tone it sounds about right. i will have a look in my book on getting the most out of Co2. just by blowing air around the room does nothing other than move still air around the leaf so new Co2 enriched air takes its place it also helps the plant transpire water off the leaf all you are doing if you do not exchange the air with fresh air is blowing stale air around the room.

again you go against what profesinal growers have been saying and doing for years!

they say dont use mirror's because they can make hot spots
you say no they dont they are the best i use them because i can see my plants the other side.

they say to exchange the air every 30x for optimum environment and to help keep mildew and pest at bay
you say no you dont all you need to do is point a fan at it.


Quote:
Multiple heat sources equalize at a lower heat. A single source can equalize to that source. It's like comparing a bunch of Bic lighters to a propane heater.
yes but they must both be burning the same amout of gas! i.e 150w CFL run hotter than HPS its well known its been looked at and looked at again and again watt for watt they are not cooler than HPS
Click to expand...
 
smoothopyro

smoothopyro

Active Member
AeroKing said:
Wow, great discussion going on here!

I have a couple things I'd like to add.

Light differs from sound. Sound is a wave that effects matter. When two sound waves hit 1 particle, both waves will effect it.
Light moves through space. When 2 lightwaves hit each other, they do not have the same "added affect" as a sound wave.

So, light pressure is different than sound.

Ok , now we've all heard this before: "Lumens do not add up", "Watts do not add up" or "Lights do not add up".
However, if you center a lux meter at a set point and turn lights on one at a time around it, the reading will rise.

Here's where it gets interesting:
If you take a measurement from 1000 watts of CFL at say 6", you'll get a high reading. You'll keep this high reading all throughout the "coverage area" that the lights are covering.
If you do this with a 1000w HPS, you'll get a much higher reading, but as you move from side-to-side along the "coverage area", It will drop.
(Since in gardening, we generally work on a flat plane, the "coverage area" will be regarded as a flat plane.)

So, we establish that a single stronger source of light will produce a higher lumen at a set distance, but an uneven pattern that tapers from this single source. Many smaller sources of light will not ever produce a higher measurement than the single source, but they will evenly blanket an area with light.

Now, let's move the other way, up and down.

Let's say you take an HPS bulb rated at 160000 lumens. At one foot, you'll read about 160k lumens. At two feet, you'll read a 1/4 of that. This is called the inverse square law. Because light radiates evenly, at double the distance, you quadruple the area that the light is now covering. (Imagine the surface area of a balloon that's 1/2way blown up vs. one that's completely blown up - Light spreads in the same way the balloon does)

So, (for our example), at 2' you have about 40k lumens. At 3', You'll have 10k, 4' = 2500 lumens...

Ok, so that's penetration. At 4' away from the light, you still have a usable amount of light (2500 lumens) that will support growth.

Now, let's try that with many smaller points of light.

Let's say you use 42 w CFLs rated at 2700 lumens.
So at 1', let's say you have so many, so close that you are recieving a total measurement of 10000 lumens - not bad right? Especially since you're getting the same amount of light that you' be getting at 3' with the HPS.

Now here's the problem: Each of these smaller sources are suseptible to their own inverse square law.
So, You can't just divide the 10000 by 4 to get 2500 at 2'. You would need to take each of the 2700 lumen sources and start quartering those. So now, you've gone from many sources adding 2700 or less to the measurement, to many sources adding 700 or less. Bulbs that are further away, now have little to no effect and the ones that are close, can't get their light far enough to really bring that number up.

Whether the source is from an HID, CFL, or LED, this rule holds true.
If a 200w CFL has a higher initial lumen than a 150w HPS, the CFL will have better penetration than the HPS.

if you want proof, google "inverse square law". This explains it all...
Click to expand...
Wow. This answered basically all of my questions. I need to treat each individual light as an individual within a system...each contributes to the overall, but each has only a fraction of the intensity as a single source. Like a sports team: each individual contributes a little, but the intensity of each individual is what's important.
 
AeroKing

AeroKing

Well-Known Member
TeaTreeOil said:
Whether the inverse square law applies to them individually is the same as it applying on the whole.

Whether you take i = 10000 lm / 2 ^ 2
i1 = 2500

Take another light source, and the same equation as above is true.

i2 = 2500

But I was already at 2500!! What would be the total intensity? i1 + i2! Of course. If it's zero it becomes 2500. Why is this (addition) so difficult?

Lets take this as a 'complex' problem and solve it at once!

We have a total of 20000 lumens. Both 2 feet from the target measuring point.

i = 20000 lm / 2 ft ^ 2
i = 20000 / 4 ft
i = 5000 lm/ft

What do yall not understand?
Click to expand...
The math makes sense, I won't dispute that. Maybe I wasn't really explaining it right.

However, we are looking for real world application.
You can't stack 1000w of CFL in the same space as an HPS bulb, so they need to be spread out.

If you pack them very tightly together, your application works. In real life, they are spread out.

So, at 2' away from the center of the source of light, you may be 2' from the bulb in the center and you may be 3' from the bulbs at the edges.

So, now your simple mathematical problem is more complicated.

Lets still keep it pretty simple and say that you have 5 bulbs each producing 10,000 lumens:

Let's say the distance from the center bulb is 2' away at the point of measurement. The 4 outer bulbs are 3' away because of their 'real life' positioning.

So, the center bulb is now shining down 2500 lumens. The 4 outer bulbs are shining about a quarter of that each, so another 2500 lumens for 5000 total lumens.

One 50000 lumen source at 2' would be 12500 lumens.

You can't negate the impossibility of stacking multiple sources of light into the same space as a single high-intensity source as an important variable.

Now to another point that really makes a difference for our application.

Light pressure also dictates the rate at which light will pass through translucent or transparent matter. No matter how many different waves are hitting the matter, how much light gets through is dictated by the intensity of the single source. They will not add up when it comes to actually "penetrating" the canopy.

You can't really see it, but light will pass through a leaf an keep moving onward to other leaves... If it didn't, only the very top layer of vegetation would receive any light and the bottom would die.

This doesn't happen with 1000w HPSs, or the sun. The light from these sources, even though much further away than a bank of CFLs will still have more propensity to penetrate through leaf matter.

CFLs do not provide the "light pressure" that a high intensity source does.

Penetration (for our application) does not equal intensity. It is a combination of variables that dictate whether the source will produce enough usable light to support growth at a set location(distance and all impedences).
 
AeroKing

AeroKing

Well-Known Member
smoothopyro said:
Wow. This answered basically all of my questions. I need to treat each individual light as an individual within a system...each contributes to the overall, but each has only a fraction of the intensity as a single source. Like a sports team: each individual contributes a little, but the intensity of each individual is what's important.
Click to expand...
Pretty much.

The thing is, with CFLs, that this weakness can also be their strength if properly exploited.

You have the ability to position them very closely to the foliage and spread out throughout the whole canopy or plant.

It is my opinion that a plant can make greater use of light if you ask a lot of the plant to do a little bit of work by providing a little bit of light to a lot of the plant vs. asking a little bit of the plant to do a lot of the work by giving the little bit of plant a lot of light.

This becomes very evident during flowering when a plant will produce more flower near the foliage that receives the most light and very little at the parts that receive low light. A plant will even shed leaves that are not receiving adequate light and grow bigger leaves at the points that are.
I believe that you're better off with the first, allowing more uniform growth and quality of harvested product through out the plant, or lollypop to manually force production to one main cola.
 
B

Bubba Kushman

Well-Known Member
I find cfls work very well for veg! I use 10 6700k 23w bulbs(100w equivilents) in a 4x4x4 cab and a 600HPS for flower. I changed over from a 400MH for veg to save energy. Brick Top is correct about the penetration but the plants really seem to respond to the cfls in veg. They get taller faster so you can flower sooner but are not quite as bushy. I think thats why so members many like them. They stretch a little more but topping can control that and If a plants tend to stretch a lot I remove one 6700k bulb and put her under one 2700k instead and the stretch slows dramatically. Like Brick Top said. You cant compare CFLs to HIDs when it comes to light penetration. The buds will allways be bigger and harder with HID lighting. Thats why I flower with a 600HPS. If you want to compare the light pentration, put a light meter on the floor under the canopy and see which one registers more light energy.
 
TeaTreeOil

TeaTreeOil

Well-Known Member
AeroKing said:
Wow, great discussion going on here!

I have a couple things I'd like to add.

Light differs from sound. Sound is a wave that effects matter. When two sound waves hit 1 particle, both waves will effect it.
Light moves through space. When 2 lightwaves hit each other, they do not have the same "added affect" as a sound wave.
Click to expand...
Hitting no. Aligning, yes, there's added 'effect'. It's called addition. It's represented by the + operator. If you shine two flashlights to form a 'cross' of light. The intersection isn't meaningful to the target surfaces. If you point two flashlights at a single point on a single target surface, yes, they add. As in addition of their intensities according to I = P / A.

Same area. Twice the power.

Ok.. how to explain this... 1 / 1 to... 2 / 1. Doubled. Same area twice the power! Twice the intensity! This is a physical law!

AeroKing said:
So, light pressure is different than sound.

Ok , now we've all heard this before: "Lumens do not add up", "Watts do not add up" or "Lights do not add up".
Click to expand...
You heard wrong. You believe everything that's said? :lol:

AeroKing said:
However, if you center a lux meter at a set point and turn lights on one at a time around it, the reading will rise.
Click to expand...
That's an interesting premise.

AeroKing said:
Here's where it gets interesting:
If you take a measurement from 1000 watts of CFL at say 6", you'll get a high reading. You'll keep this high reading all throughout the "coverage area" that the lights are covering.
If you do this with a 1000w HPS, you'll get a much higher reading,
Click to expand...
At 6"? Maybe. The idea is CFLs can be closer, so they make-up for decay! You keep 1000w HPS 6" away from plants?? I keep CFLs within inches.

70 lm/w CFL at 1 foot(cfl) = 140 lm/w at 1.4 feet(HPS)

Get it yet? Unless you can get your HPS within 1.4 TIMES that of CFL. You're losing out.

AeroKing said:
but as you move from side-to-side along the "coverage area", It will drop.
Click to expand...
Right. sqrt(4' ^ 2 + 2' ^ 2 + 2' ^ 2) = distance

I=lumens/distance ^ 2

Figure it out.

AeroKing said:
(Since in gardening, we generally work on a flat plane, the "coverage area" will be regarded as a flat plane.)

So, we establish that a single stronger source of light will produce a higher lumen at a set distance, but an uneven pattern that tapers from this single source. Many smaller sources of light will not ever produce a higher measurement than the single source, but they will evenly blanket an area with light.
Click to expand...
WRONG! Light is additive. You just countered your premise!!!! WTF! :cuss:

AeroKing said:
Now, let's move the other way, up and down.

Let's say you take an HPS bulb rated at 160000 lumens. At one foot, you'll read about 160k lumens. At two feet, you'll read a 1/4 of that. This is called the inverse square law. Because light radiates evenly, at double the distance, you quadruple the area that the light is now covering. (Imagine the surface area of a balloon that's 1/2way blown up vs. one that's completely blown up - Light spreads in the same way the balloon does)

So, (for our example), at 2' you have about 40k lumens. At 3', You'll have 10k, 4' = 2500 lumens...
Click to expand...
Yes, 2'. 2x2 = 4. 160,000/4 = 40k lm.
3' is 3x3 = 9. 160,000/9 = 17,778 lm.
4' is 4x4 = 16. 160,000/16 = 10,000 lm.

Apparently you've developed a mythical 160 lm/W HPS bulb, sounds cool.

Realistically(maximum output) we get:
35k lm
15,556 lm
8750 lm

AeroKing said:
Ok, so that's penetration. At 4' away from the light, you still have a usable amount of light (2500 lumens) that will support growth.

Now, let's try that with many smaller points of light.

Let's say you use 42 w CFLs rated at 2700 lumens.
So at 1', let's say you have so many, so close that you are recieving a total measurement of 10000 lumens - not bad right? Especially since you're getting the same amount of light that you' be getting at 3' with the HPS.

Now here's the problem: Each of these smaller sources are suseptible to their own inverse square law.
So, You can't just divide the 10000 by 4 to get 2500 at 2'. You would need to take each of the 2700 lumen sources and start quartering those.
Click to expand...
That makes no sense. Four 42w bulbs at 2800 lumens is 11,200 lumens at one foot away from all of them(equidistant). To divide by 4 would mean two feet away. In which case you get 2800 lumens!

Just as 2 feet dimished intensity 4 times(so 4x the light MAINTAINS it at double the distance). A half foot increases intensity 4 times.

AeroKing said:
So now, you've gone from many sources adding 2700 or less to the measurement, to many sources adding 700 or less. Bulbs that are further away, now have little to no effect and the ones that are close, can't get their light far enough to really bring that number up.
Click to expand...
Light is additive. This is a law. Look it up.

AeroKing said:

Whether the source is from an HID, CFL, or LED, this rule holds true.
If a 200w CFL has a higher initial lumen than a 150w HPS, the CFL will have better penetration than the HPS.

if you want proof, google "inverse square law". This explains it all...
Click to expand...
Too bad you can't explain it. :eyesmoke:
 
Brick Top

Brick Top

New Member
psg1 said:
Brick_Top: Some reading material for you: http://www.icmag.com/ic/showthread.php?t=99879&page=1&pp=15
Click to expand...


Thank you for the link but I have been doing this for 37 years, am part owner of a nursery, trees and bushes and not plants or taking care of kids, and there are four botanists in my family.

Between what I have experienced over the decades and what I have read and what I have learned from people with degrees in botany I tend to believe all that over what is found in a thread on a grow site or what people with decades less experience and general growing knowledge and who do not have botanists for family members and who have nickel and dime penny ante ghetto grows inaccurately claim.
 
TeaTreeOil

TeaTreeOil

Well-Known Member
Brick Top said:
Thank you for the link but I have been doing this for 37 years, am part owner of a nursery, trees and bushes and not plants or taking care of kids, and there are four botanists in my family.

Between what I have experienced over the decades and what I have read and what I have learned from people with degrees in botany I tend to believe all that over what is found in a thread on a grow site or what people with decades less experience and general growing knowledge and who do not have botanists for family members and who have nickel and dime, penny ante
ghetto grows inaccurately claim.
Click to expand...
Yes, indeed, assumption is much easier.
 
Brick Top

Brick Top

New Member
TeaTreeOil said:
Yes, indeed, assumption is much easier.
Click to expand...

That of course came from someone who inaccurately claimed that aluminum foil is a good reflector and attempted to validate that by assuming that the aluminum alloy that aluminum foil is made of has the same reflective capability as high grade pure aluminum that is pebbled or textured.

There was no assumption in what I wrote. It came from decades of experience, vast amounts of reading factual information, and not the opinion of people who do not know what they are talking about but like to claim they do, and what has been told to me by four family members with degrees in botany.

I guess your science teacher fount of all knowledge wife has been filling your head with nonsense again, well that and relying on Wiki for information.
 
Greyskull

Greyskull

Well-Known Member
When 1000w of CFLs can do this over a 4x4 (1.5lbs) then maybe they will get more respect from me....






Until then they are good for personal grows only. and referencing nursefraudblueskirt... he claims he get over 2g per watt - thats why hes a douchnozzel!!! IT AIN'T TRUE. that said he grows for himself rather fine...but no production value whatsoever in CFL technology.

If CFLs were the "way to go" how many pro cash croppers would be rocking the CFL tip - every last one of them. How many cash croppers are using them as primary light sources?
 
You must log in or register to reply here.
Top