Resistors are normally made from a carbon film or a metal film that
control the flow of current. Resistors are normally made in a wide
variety of sizes, shapes and designs; usually, they have a colour coded
system of determining the value.
Friday 18 October 2013
Thursday 17 October 2013
ELECTROMAGNETIC SPECTRUM
The electromagnetic spectrum is the range of all possible frequencies of electromagnetic radiation. The "electromagnetic spectrum" of an object
has a different meaning, and is instead the characteristic distribution
of electromagnetic radiation emitted or absorbed by that particular
object.
The types of electromagnetic radiation are broadly classified into the following classes:
This classification goes in the increasing order of wavelength, which is characteristic of the type of radiation
Gamma radiation, also known as gamma rays, and denoted by the Greek letter γ, refers to electromagnetic radiation of high frequency and therefore high energy per photon. Gamma rays are ionizing radiation, and are thus biologically hazardous. They are classically produced by the decay from high energy states of atomic nuclei (gamma decay), but are also created by other processes. Paul Villard, a French chemist and physicist, discovered gamma radiation in 1900, while studying radiation emitted from radium. Villard's radiation was named "gamma rays" by Ernest Rutherford in 1903.
Gamma rays typically have frequencies above 10 exahertz (or >1019 Hz), and therefore have energies above 100 keV and wavelengths less than 10 picometers (less than the diameter of an atom).
X-radiation (composed of X-rays) is a form of electromagnetic radiation however much higher-energy X-rays can be generated for medical and industrial uses, for example radiotherapy, which utilizes linear accelerators to generate X-rays in the ranges of 6-20 MeV.
Most X-rays have a wavelength in the range of 0.01 to 10 nanometers, corresponding to frequencies in the range 30 petahertz to 30 exahertz (3×1016 Hz to 3×1019 Hz) and energies in the range 100 eV to 100 keV.
Ultraviolet (UV) light is electromagnetic radiation with a wavelength shorter than that of visible light, but longer than X-rays, that is, in the range between 400 nm and 10 nm, corresponding to photon energies from 3 eV to 124 eV. It is so-named because the spectrum consists of electromagnetic waves with frequencies higher than those that humans identify as the color violet. These frequencies are invisible to humans, but near UV is visible to a number of insects and birds.
The visible spectrum is the portion of the electromagnetic spectrum that is visible to (can be detected by) the human eye. Electromagnetic radiation in this range of wavelengths is called visible light or simply light. A typical human eye will respond to wavelengths from about 390 to 700 nm.[1] In terms of frequency, this corresponds to a band in the vicinity of 430–790 THz. A light-adapted eye generally has its maximum sensitivity at around 555 nm (540 THz), in the green region of the optical spectrum (see: luminosity function). The spectrum does not, however, contain all the colors that the human eyes and brain can distinguish.
Infrared (IR) light is electromagnetic radiation with longer wavelengths than those of visible light, extending from the nominal red edge of the visible spectrum at 700 nanometres (nm) to 1 mm. This range of wavelengths corresponds to a frequency range of approximately 430 THz down to 300 GHz,.[1] Most of the thermal radiation emitted by objects near room temperature is infrared.
In physics, terahertz radiation, also called submillimeter radiation, terahertz waves, terahertz light, T-rays, T-waves, T-light, T-lux, or THz, consists of electromagnetic waves at frequencies from 0.3 to 3 terahertz (THz). The term applies to electromagnetic radiation with frequencies between the high-frequency edge of the millimeter wave band, 300 gigahertz (3×1011 Hz), and the low frequency edge of the far-infrared light band, 3000 GHz (3×1012 Hz). Corresponding wavelengths of radiation in this band range from 1 mm to 0.1 mm
Microwaves are a form of electromagnetic radiation with wavelengths ranging from as long as one meter to as short as one millimeter, or equivalently, with frequencies between 300 MHz (0.3 GHz) and 300 GHz.[1][2] This broad definition includes both UHF and EHF (millimeter waves), and various sources use different boundaries. In all cases, microwave includes the entire SHF band (3 to 30 GHz, or 10 to 1 cm) at minimum, with RF engineering often putting the lower boundary at 1 GHz (30 cm), and the upper around 100 GHz (3 mm).
Radio waves are a type of electromagnetic radiation with wavelengths in the electromagnetic spectrum longer than infrared light. Radio waves have frequencies from 300 GHz to as low as 3 kHz, and corresponding wavelengths ranging from 1 millimeter (0.039 in) to 100 kilometers (62 mi). Like all other electromagnetic waves, they travel at the speed of light. Naturally occurring radio waves are made by lightning, or by astronomical objects. Artificially generated radio waves are used for fixed and mobile radio communication, broadcasting, radar and other navigation systems, communications satellites, computer networks and innumerable other applications. Different frequencies of radio waves have different propagation characteristics in the Earth's atmosphere; long waves may cover a part of the Earth very consistently, shorter waves can reflect off the ionosphere and travel around the world, and much shorter wavelengths bend or reflect very little and travel on a line of sight.
The types of electromagnetic radiation are broadly classified into the following classes:
- Gamma radiation
- X-ray radiation
- Ultraviolet radiation
- Visible radiation
- Infrared radiation
- Terahertz radiation
- Microwave radiation
- Radio waves
This classification goes in the increasing order of wavelength, which is characteristic of the type of radiation
Gamma radiation, also known as gamma rays, and denoted by the Greek letter γ, refers to electromagnetic radiation of high frequency and therefore high energy per photon. Gamma rays are ionizing radiation, and are thus biologically hazardous. They are classically produced by the decay from high energy states of atomic nuclei (gamma decay), but are also created by other processes. Paul Villard, a French chemist and physicist, discovered gamma radiation in 1900, while studying radiation emitted from radium. Villard's radiation was named "gamma rays" by Ernest Rutherford in 1903.
Gamma rays typically have frequencies above 10 exahertz (or >1019 Hz), and therefore have energies above 100 keV and wavelengths less than 10 picometers (less than the diameter of an atom).
X-radiation (composed of X-rays) is a form of electromagnetic radiation however much higher-energy X-rays can be generated for medical and industrial uses, for example radiotherapy, which utilizes linear accelerators to generate X-rays in the ranges of 6-20 MeV.
Most X-rays have a wavelength in the range of 0.01 to 10 nanometers, corresponding to frequencies in the range 30 petahertz to 30 exahertz (3×1016 Hz to 3×1019 Hz) and energies in the range 100 eV to 100 keV.
Ultraviolet (UV) light is electromagnetic radiation with a wavelength shorter than that of visible light, but longer than X-rays, that is, in the range between 400 nm and 10 nm, corresponding to photon energies from 3 eV to 124 eV. It is so-named because the spectrum consists of electromagnetic waves with frequencies higher than those that humans identify as the color violet. These frequencies are invisible to humans, but near UV is visible to a number of insects and birds.
The visible spectrum is the portion of the electromagnetic spectrum that is visible to (can be detected by) the human eye. Electromagnetic radiation in this range of wavelengths is called visible light or simply light. A typical human eye will respond to wavelengths from about 390 to 700 nm.[1] In terms of frequency, this corresponds to a band in the vicinity of 430–790 THz. A light-adapted eye generally has its maximum sensitivity at around 555 nm (540 THz), in the green region of the optical spectrum (see: luminosity function). The spectrum does not, however, contain all the colors that the human eyes and brain can distinguish.
Infrared (IR) light is electromagnetic radiation with longer wavelengths than those of visible light, extending from the nominal red edge of the visible spectrum at 700 nanometres (nm) to 1 mm. This range of wavelengths corresponds to a frequency range of approximately 430 THz down to 300 GHz,.[1] Most of the thermal radiation emitted by objects near room temperature is infrared.
In physics, terahertz radiation, also called submillimeter radiation, terahertz waves, terahertz light, T-rays, T-waves, T-light, T-lux, or THz, consists of electromagnetic waves at frequencies from 0.3 to 3 terahertz (THz). The term applies to electromagnetic radiation with frequencies between the high-frequency edge of the millimeter wave band, 300 gigahertz (3×1011 Hz), and the low frequency edge of the far-infrared light band, 3000 GHz (3×1012 Hz). Corresponding wavelengths of radiation in this band range from 1 mm to 0.1 mm
Microwaves are a form of electromagnetic radiation with wavelengths ranging from as long as one meter to as short as one millimeter, or equivalently, with frequencies between 300 MHz (0.3 GHz) and 300 GHz.[1][2] This broad definition includes both UHF and EHF (millimeter waves), and various sources use different boundaries. In all cases, microwave includes the entire SHF band (3 to 30 GHz, or 10 to 1 cm) at minimum, with RF engineering often putting the lower boundary at 1 GHz (30 cm), and the upper around 100 GHz (3 mm).
Radio waves are a type of electromagnetic radiation with wavelengths in the electromagnetic spectrum longer than infrared light. Radio waves have frequencies from 300 GHz to as low as 3 kHz, and corresponding wavelengths ranging from 1 millimeter (0.039 in) to 100 kilometers (62 mi). Like all other electromagnetic waves, they travel at the speed of light. Naturally occurring radio waves are made by lightning, or by astronomical objects. Artificially generated radio waves are used for fixed and mobile radio communication, broadcasting, radar and other navigation systems, communications satellites, computer networks and innumerable other applications. Different frequencies of radio waves have different propagation characteristics in the Earth's atmosphere; long waves may cover a part of the Earth very consistently, shorter waves can reflect off the ionosphere and travel around the world, and much shorter wavelengths bend or reflect very little and travel on a line of sight.
Wednesday 16 October 2013
ELECTROMAGNETIC RADIATION
Electromagnetic radiation (EM radiation or EMR) is one of the fundamental phenomena of electromagnetism, exhibiting wave-like behavior as it propagates through space carrying radiant energy. It is emitted and absorbed by charged particles. EMR has both electric and magnetic field components, which stand in a fixed ratio of intensity to each other, and which oscillate in phase perpendicular to each other and perpendicular to the direction of energy and wave propagation. In a vacuum, electromagnetic radiation propagates at a characteristic speed, the speed of light.
Electromagnetic Force
The electromagnetic force is one of the four fundamental interactions in nature, the other three being the strong interaction, the weak interaction, and gravitation. This force is described by electromagnetic fields, and has innumerable physical instances including the interaction of electrically charged particles and the interaction of uncharged magnetic force fields with electrical conductors.
Types of Forces
| There are mainly three types of forces that exist in this universe and mainly categorized in the forces of nature | |||
-Gravitational Force |
|
||||||||
-Electrical Force |
-Magnetic ForceThe combination of electromagnetic force and Magnetic force is said to be electromagnetic force which is said to be strongest force in the nature. |
Radio Frequency (RF)
Radio frequency (RF) is a rate of oscillation in the range of about 3 kHz to 300 GHz, which corresponds to the frequency of radio waves, and the alternating currents which carry radio signals.
Keyboard Shortcuts (Microsoft Windows)
More than 100 Keyboard Shortcuts
1. CTRL+C (Copy)
2. CTRL+X (Cut)
3. CTRL+V (Paste)
4. CTRL+Z (Undo)
5. DELETE (Delete)
6. SHIFT+DELETE (Delete the selected
item permanently without placing the
item in the Recycle Bin)
7. CTRL while dragging an item (Copy the
selected item)
8. CTRL+SHIFT while dragging an item
(Create a shortcut to the selected item)
9. F2 key (Rename the selected item)
10. CTRL+RIGHT ARROW (Move the
insertion point to the beginning of the
next word)
11. CTRL+LEFT ARROW (Move the
insertion point to the beginning of the
previous word)
12. CTRL+DOWN ARROW (Move the
insertion point to the beginning of the
next paragraph)
13. CTRL+UP ARROW (Move the
insertion point to the beginning of the
previous paragraph)
14. CTRL+SHIFT with any of the arrow
keys (Highlight a block of text)
SHIFT with any of the arrow keys (Select
more than one item in a window or on
the desktop, or select text in a
document)
15. CTRL+A (Select all)
16. F3 key (Search for a file or a folder)
17. ALT+ENTER (View the properties for
the selected item)
18. ALT+F4 (Close the active item, or quit
the active program)
19. ALT+ENTER (Display the properties
of the selected object)
20. ALT+SPACEBAR (Open the shortcut
menu for the active window)
21. CTRL+F4 (Close the active document
in programs that enable you to have
multiple documents opensimultaneously)
22. ALT+TAB (Switch between the open
items)
23. ALT+ESC (Cycle through items in the
order that they had been opened)
24. F6 key (Cycle through the screen
elements in a window or on the desktop)
25. F4 key (Display the Address bar list in
My Computer or Windows Explorer)
26. SHIFT+F10 (Display the shortcut
menu for the selected item)
27. ALT+SPACEBAR (Display the System
menu for the active window)
28. CTRL+ESC (Display the Start menu)
29. ALT+Underlined letter in a menu
name (Display the corresponding menu)
Underlined letter in a command name on
an open menu (Perform the
corresponding command)
30. F10 key (Activate the menu bar in the
active program)
31. RIGHT ARROW (Open the next menu
to the right, or open a submenu)
32. LEFT ARROW (Open the next menu to
the left, or close a submenu)
33. F5 key (Update the active window)
34. BACKSPACE (View the folder onelevel
up in My Computer or Windows
Explorer)
35. ESC (Cancel the current task)
36. SHIFT when you insert a CD-ROMinto
the CD-ROM drive (Prevent the CD-ROM
from automatically playing)
Dialog Box - Keyboard Shortcuts
1. CTRL+TAB (Move forward through the
tabs)
2. CTRL+SHIFT+TAB (Move backward
through the tabs)
3. TAB (Move forward through the
options)
4. SHIFT+TAB (Move backward through
the options)
5. ALT+Underlined letter (Perform the
corresponding command or select the
corresponding option)
6. ENTER (Perform the command for the
active option or button)
7. SPACEBAR (Select or clear the check
box if the active option is a check box)
8. Arrow keys (Select a button if the
active option is a group of option
buttons)
9. F1 key (Display Help)
10. F4 key (Display the items in the
active list)
11. BACKSPACE (Open a folder one level
up if a folder is selected in the Save As
or Open dialog box)
Microsoft Natural Keyboard Shortcuts
1. Windows Logo (Display or hide the
Start menu)
2. Windows Logo+BREAK (Display the
System Properties dialog box)
3. Windows Logo+D (Display the
desktop)
4. Windows Logo+M (Minimize all of the
windows)
5. Windows Logo+SHIFT+M (Restorethe
minimized windows)
6. Windows Logo+E (Open My
Computer)
7. Windows Logo+F (Search for a file or a
folder)
8. CTRL+Windows Logo+F (Search for
computers)
9. Windows Logo+F1 (Display Windows
Help)
10. Windows Logo+ L (Lock the
keyboard)
11. Windows Logo+R (Open the Run
dialog box)
12. Windows Logo+U (Open Utility
Manager)
13. Accessibility Keyboard Shortcuts
14. Right SHIFT for eight seconds (Switch
FilterKeys either on or off)
15. Left ALT+left SHIFT+PRINT SCREEN
(Switch High Contrast either on or off)
16. Left ALT+left SHIFT+NUM LOCK
(Switch the MouseKeys either on or off)
17. SHIFT five times (Switch the
StickyKeys either on or off)
18. NUM LOCK for five seconds (Switch
the ToggleKeys either on or off)
19. Windows Logo +U (Open Utility
Manager)
20. Windows Explorer Keyboard
Shortcuts
21. END (Display the bottom of the
active window)
22. HOME (Display the top of the active
window)
23. NUM LOCK+Asterisk sign (*) (Display
all of the subfolders that are under the
selected folder)
24. NUM LOCK+Plus sign (+) (Display the
contents of the selected folder)
MMC Console keyboard shortcuts
1. SHIFT+F10 (Display the Action
shortcut menu for the selected item)
2. F1 key (Open the Help topic, if any, for
the selected item)
3. F5 key (Update the content of all
console windows)
4. CTRL+F10 (Maximize the active
console window)
5. CTRL+F5 (Restore the active console
window)
6. ALT+ENTER (Display the Properties
dialog box, if any, for theselected item)
7. F2 key (Rename the selected item)
8. CTRL+F4 (Close the active console
window. When a console has only one
console window, this shortcut closes the
console)
Remote Desktop Connection Navigation
1. CTRL+ALT+END (Open the Microsoft
Windows NT Security dialog box)
2. ALT+PAGE UP (Switch between
programs from left to right)
3. ALT+PAGE DOWN (Switch between
programs from right to left)
4. ALT+INSERT (Cycle through the
programs in most recently used order)
5. ALT+HOME (Display the Start menu)
6. CTRL+ALT+BREAK (Switch the client
computer between a window and a full
screen)
7. ALT+DELETE (Display the Windows
menu)
8. CTRL+ALT+Minus sign (-) (Place a
snapshot of the active window in the
client on the Terminal server clipboard
and provide the same functionality as
pressing PRINT SCREEN on a local
computer.)
9. CTRL+ALT+Plus sign (+) (Place
asnapshot of the entire client window
area on the Terminal server clipboardand
provide the same functionality
aspressing ALT+PRINT SCREEN on a
local computer.)
Microsoft Internet Explorer Keyboard
Shortcuts
1. CTRL+B (Open the Organize Favorites
dialog box)
2. CTRL+E (Open the Search bar)
3. CTRL+F (Start the Find utility)
4. CTRL+H (Open the History bar)
5. CTRL+I (Open the Favorites bar)
6. CTRL+L (Open the Open dialog box)
7. CTRL+N (Start another instance of the
browser with the same Web address)
8. CTRL+O (Open the Open dialog
box,the same as CTRL+L)
9. CTRL+P (Open the Print dialog box)
10. CTRL+R (Update the current Web
page)
11. CTRL+W (Close the current window
1. CTRL+C (Copy)
2. CTRL+X (Cut)
3. CTRL+V (Paste)
4. CTRL+Z (Undo)
5. DELETE (Delete)
6. SHIFT+DELETE (Delete the selected
item permanently without placing the
item in the Recycle Bin)
7. CTRL while dragging an item (Copy the
selected item)
8. CTRL+SHIFT while dragging an item
(Create a shortcut to the selected item)
9. F2 key (Rename the selected item)
10. CTRL+RIGHT ARROW (Move the
insertion point to the beginning of the
next word)
11. CTRL+LEFT ARROW (Move the
insertion point to the beginning of the
previous word)
12. CTRL+DOWN ARROW (Move the
insertion point to the beginning of the
next paragraph)
13. CTRL+UP ARROW (Move the
insertion point to the beginning of the
previous paragraph)
14. CTRL+SHIFT with any of the arrow
keys (Highlight a block of text)
SHIFT with any of the arrow keys (Select
more than one item in a window or on
the desktop, or select text in a
document)
15. CTRL+A (Select all)
16. F3 key (Search for a file or a folder)
17. ALT+ENTER (View the properties for
the selected item)
18. ALT+F4 (Close the active item, or quit
the active program)
19. ALT+ENTER (Display the properties
of the selected object)
20. ALT+SPACEBAR (Open the shortcut
menu for the active window)
21. CTRL+F4 (Close the active document
in programs that enable you to have
multiple documents opensimultaneously)
22. ALT+TAB (Switch between the open
items)
23. ALT+ESC (Cycle through items in the
order that they had been opened)
24. F6 key (Cycle through the screen
elements in a window or on the desktop)
25. F4 key (Display the Address bar list in
My Computer or Windows Explorer)
26. SHIFT+F10 (Display the shortcut
menu for the selected item)
27. ALT+SPACEBAR (Display the System
menu for the active window)
28. CTRL+ESC (Display the Start menu)
29. ALT+Underlined letter in a menu
name (Display the corresponding menu)
Underlined letter in a command name on
an open menu (Perform the
corresponding command)
30. F10 key (Activate the menu bar in the
active program)
31. RIGHT ARROW (Open the next menu
to the right, or open a submenu)
32. LEFT ARROW (Open the next menu to
the left, or close a submenu)
33. F5 key (Update the active window)
34. BACKSPACE (View the folder onelevel
up in My Computer or Windows
Explorer)
35. ESC (Cancel the current task)
36. SHIFT when you insert a CD-ROMinto
the CD-ROM drive (Prevent the CD-ROM
from automatically playing)
Dialog Box - Keyboard Shortcuts
1. CTRL+TAB (Move forward through the
tabs)
2. CTRL+SHIFT+TAB (Move backward
through the tabs)
3. TAB (Move forward through the
options)
4. SHIFT+TAB (Move backward through
the options)
5. ALT+Underlined letter (Perform the
corresponding command or select the
corresponding option)
6. ENTER (Perform the command for the
active option or button)
7. SPACEBAR (Select or clear the check
box if the active option is a check box)
8. Arrow keys (Select a button if the
active option is a group of option
buttons)
9. F1 key (Display Help)
10. F4 key (Display the items in the
active list)
11. BACKSPACE (Open a folder one level
up if a folder is selected in the Save As
or Open dialog box)
Microsoft Natural Keyboard Shortcuts
1. Windows Logo (Display or hide the
Start menu)
2. Windows Logo+BREAK (Display the
System Properties dialog box)
3. Windows Logo+D (Display the
desktop)
4. Windows Logo+M (Minimize all of the
windows)
5. Windows Logo+SHIFT+M (Restorethe
minimized windows)
6. Windows Logo+E (Open My
Computer)
7. Windows Logo+F (Search for a file or a
folder)
8. CTRL+Windows Logo+F (Search for
computers)
9. Windows Logo+F1 (Display Windows
Help)
10. Windows Logo+ L (Lock the
keyboard)
11. Windows Logo+R (Open the Run
dialog box)
12. Windows Logo+U (Open Utility
Manager)
13. Accessibility Keyboard Shortcuts
14. Right SHIFT for eight seconds (Switch
FilterKeys either on or off)
15. Left ALT+left SHIFT+PRINT SCREEN
(Switch High Contrast either on or off)
16. Left ALT+left SHIFT+NUM LOCK
(Switch the MouseKeys either on or off)
17. SHIFT five times (Switch the
StickyKeys either on or off)
18. NUM LOCK for five seconds (Switch
the ToggleKeys either on or off)
19. Windows Logo +U (Open Utility
Manager)
20. Windows Explorer Keyboard
Shortcuts
21. END (Display the bottom of the
active window)
22. HOME (Display the top of the active
window)
23. NUM LOCK+Asterisk sign (*) (Display
all of the subfolders that are under the
selected folder)
24. NUM LOCK+Plus sign (+) (Display the
contents of the selected folder)
MMC Console keyboard shortcuts
1. SHIFT+F10 (Display the Action
shortcut menu for the selected item)
2. F1 key (Open the Help topic, if any, for
the selected item)
3. F5 key (Update the content of all
console windows)
4. CTRL+F10 (Maximize the active
console window)
5. CTRL+F5 (Restore the active console
window)
6. ALT+ENTER (Display the Properties
dialog box, if any, for theselected item)
7. F2 key (Rename the selected item)
8. CTRL+F4 (Close the active console
window. When a console has only one
console window, this shortcut closes the
console)
Remote Desktop Connection Navigation
1. CTRL+ALT+END (Open the Microsoft
Windows NT Security dialog box)
2. ALT+PAGE UP (Switch between
programs from left to right)
3. ALT+PAGE DOWN (Switch between
programs from right to left)
4. ALT+INSERT (Cycle through the
programs in most recently used order)
5. ALT+HOME (Display the Start menu)
6. CTRL+ALT+BREAK (Switch the client
computer between a window and a full
screen)
7. ALT+DELETE (Display the Windows
menu)
8. CTRL+ALT+Minus sign (-) (Place a
snapshot of the active window in the
client on the Terminal server clipboard
and provide the same functionality as
pressing PRINT SCREEN on a local
computer.)
9. CTRL+ALT+Plus sign (+) (Place
asnapshot of the entire client window
area on the Terminal server clipboardand
provide the same functionality
aspressing ALT+PRINT SCREEN on a
local computer.)
Microsoft Internet Explorer Keyboard
Shortcuts
1. CTRL+B (Open the Organize Favorites
dialog box)
2. CTRL+E (Open the Search bar)
3. CTRL+F (Start the Find utility)
4. CTRL+H (Open the History bar)
5. CTRL+I (Open the Favorites bar)
6. CTRL+L (Open the Open dialog box)
7. CTRL+N (Start another instance of the
browser with the same Web address)
8. CTRL+O (Open the Open dialog
box,the same as CTRL+L)
9. CTRL+P (Open the Print dialog box)
10. CTRL+R (Update the current Web
page)
11. CTRL+W (Close the current window
Wednesday 2 October 2013
What is the difference between router,Hub and switch?
HUB
A common connection point for devices in a network. 
SWITCH
In networks, a device that filters and forwards packets between LAN segments.
A device that forwards data packets along networks. A router is connected to at least two networks, commonly two LANs orWANs or a LAN and its ISP.s network.
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