Computer Science

Computer Science and Its areas

Computer Science is the study of computers and computational systems. Unlike electrical and computer engineering, computer science deal mostly with software and software systems which include their theory, design, development, and application.

Principal areas of study within Computer Science include artificial intelligence(Ai), computer systems, and networks, security, database systems, human-computer interaction, vision and graphics, numerical analysis, programming languages, software engineering, bioinformatics, and theory of computing.

Artificial Intelligence(AI):

Unlike the natural intelligence displayed by humans and animals(which involves consciousness and emotionality), Artificial intelligence (AI) is intelligence demonstrated by machines. Artificial intelligence was founded as an academic discipline in 1955. and since then has experienced several waves of optimism, disappointment, and the loss of funding (known as an "AI winter"), followed by new approaches, success, and renewed funding. Artificial intelligence once again attracted widespread global attention after Alpha Go successfully defeated a professional Go player in 2015. Now AI techniques have experienced a resurgence following concurrent advances in computer power, large amounts of data, and theoretical understanding; and AI techniques have become an essential part of the technology industry, helping to solve many challenging problems in computer science, software engineering, and operations research.

Computer systems:

Computer System is a collection of entities(hardware, software, and liveware) that are designed to receive, process, manage and present information in a meaningful format.

• Computer hardware: Computer hardware Are physical parts/ intangible parts of a computer. eg Input devices, output devices, central processing unit, and storage devices
• Computer software: Computer software is also known as programs or applications. They are classified into two classes namely - system software and application software
• Liveware: Liveware is the computer user. Also, known as orgwareor the humanware. The user commands the computer system to execute instructions.

Networks:

A network is a collection of computers, servers, mainframes, network devices, peripherals, or other devices connected to one another to allow the sharing of data. As an example Internet connects millions of people all over the world. There are mainly four types of computer networks.

• LAN(Local Area Network)
• PAN(Personal Area Network)
• MAN(Metropolitan Area Network)
• WAN(Wide Area Network)

Security:

Computer security, cybersecurity or information technology security is the protection of computer systems and networks from the theft of or damage to their hardware, software, or electronic data, as well as from the disruption or misdirection of the services they provide. (Wikipedia)

Database systems:

A database is an organized collection of structured information, or data, typically stored electronically in a computer system. A database refers to a set of related data and the way it is organized. This data is accessed by a Database Management System (DBMS) which consists of an integrated set of computer software that allows users to interact with one or more databases and provides access to all of the data contained in the database.

Human-Computer interaction:

Human-computer interaction(HCI) is a multidisciplinary field of study focusing on the design of computer technology and, in particular, the interaction between humans and computers.

Vision and graphics:

Visual computing is a generic term for all computer science disciplines dealing with images and 3D models, such as computer graphics, image processing, visualization, computer vision, virtual and augmented reality, and video processing.

Numerical analysis:

Numerical analysis, an area of mathematics and computer science that creates, analyzes, and implements algorithms for obtaining numerical solutions to problems involving continuous variables. Numerical analysis is concerned with all aspects of the numerical solution of a problem, from the theoretical development and understanding of numerical methods to their practical implementation as reliable and efficient computer programs.

Programming languages:

Computer programming languages allow us to give instructions to a computer in a language the computer understands. Just as many human-based languages exist, there are an array of computer programming languages that programmers can use to communicate with a computer. Some of those languages are:

• Python
• C/C++
• Java
• Ruby
• Swift

Software engineering:

Software engineering is a detailed study of engineering to the design, development and maintenance of software. Software engineering was introduced to address the issues of low-quality software projects.

Bioinformatics:

Bioinformatics is an interdisciplinary field bringing together biology, computer science, mathematics, statistics, and information theory to analyze biological data for interpretation and prediction. One popular approach is to develop a predictive computer model from a database of known gene sequences and use the resulting model to predict where genes are likely to be in newly generated sequence information.

Theory of computing:

The theory of computation is the branch that deals with what problems can be solved on a model of computation, using an algorithm, how efficiently they can be solved, or to what degree (e.g., approximate solutions versus precise ones).

Blender 2.9+ shortcuts

Blender Shortcuts

Here are all the commands which are universally accepted as Blender shortcuts across all the Blender versions. Here are all the most commonly used Blender shortcut keys used by Blender users across the world

General Shortcuts

Function	Shortcut
Open toolbar	T
Open properties	N
Add object/Node	Shift+A
Delete	X or Delete
Search for function	F3
Move	G
Scale	S
Rotate	R
Move, Scale or Rotate along the axis	G, S, or R then X/Y/Z
Move, Scale or Rotate along local axis	G, S, or R then X+X/Y+Y/Z+Z
Trackball Rotate	R+R
Precise movement	Shift (Hold)
Incremental movement	Ctrl (Hold)
Duplicate	Shift+D
Duplicate Linked	Alt+D
Hide	H
Unhide All	Alt+H
Hide All except selected	Shift+H
Annotate	D(Hold)+LMB(Drag)
Erase Annotation	D(Hold)+RMB(Drag)
Quick Favs Menu	Q

Navigation 3D viewport

Pie of View.

Function	Shortcut
Orbit	MMB(Drag)
Pan	Shift+MMB(Drag)
Zoom in/out	Scroll or Shift+MMB(Drag)
Fly	Shift+~
Get out of the Flying mode	RMB
Isolate	Numpad /
Focus	Numpad .
Camera	Numpad 0
Front view	Numpad 1
Go Down	Numpad 2
Side View	Numpad 3
Perspective-Orthographic	Numpad 5
Top view	Numpad 7
Go Up	Numpad 8
Opposite view	Numpad 9
Pie view menu	~
Fast view switch	Alt+MMB(Drag)
Show all objects	Home
Zoom to region	Shift+B

Windows keyboard shortcuts

Keyboard Shortcuts

CTRL+A. . . . . . . . . . . . . . . . . Select All

CTRL+C. . . . . . . . . . . . . . . . . Copy

CTRL+X. . . . . . . . . . . . . . . . . Cut

CTRL+V. . . . . . . . . . . . . . . . . Paste

CTRL+Z. . . . . . . . . . . . . . . . . Undo

CTRL+B. . . . . . . . . . . . . . . . . Bold

CTRL+U. . . . . . . . . . . . . . . . . Underline

CTRL+I . . . . . . . . . . . . . . . . . Italic

F1 . . . . . . . . . . . . . . . . . . . . . . Help

F2 . . . . . . . . . . . . . . . . . . . ... . Rename selected object

F3 . . . . . . . . . . . . . . . . . . . ... . Find all files

F4 . . . . . . . . . . . . . . . . . . .. . . Opens file list drop-down in dialogs

F5 . . . . . . . . . . . . . . . . . . . .. . Refresh current window

F6 . . . . . . . . . . . . . . . . . . . . . Shifts focus in Windows Explorer

F10 . . . . . . . . . . . . . . . . . . . . Activates menu bar options

ALT+TAB . . . . . . . . . . . . . . . . Cycles between open applications

ALT+F4 . . . . . . . . . . . . . . . . . Quit program, close current window

ALT+F6 . . . . . . . . . . . . . . . . . Switch between current program windows

ALT+ENTER. . . . . . . . . . . . . . Opens properties dialog

ALT+SPACE . . . . . . . . . . . . . . System menu for current window

ALT+¢ . . . . . . . . . . . . . . . . . . opens drop-down lists in dialog boxes

BACKSPACE . . . . . . . . . . . . . Switch to parent folder

CTRL+ESC . . . . . . . . . . . . . . Opens Start menu

CTRL+ALT+DEL . . . . . . . . . . Opens task manager, reboots the computer

CTRL+TAB . . . . . . . . . . . . . . Move through property tabs

CTRL+SHIFT+DRAG . . . . . . . Create shortcut (also right-click, drag)

CTRL+DRAG . . . . . . . . . . . . . Copy File

ESC . . . . . . . . . . . . . . . . . . . Cancel last function

SHIFT . . . . . . . . . . . . . . . . . . Press/hold SHIFT, insert CD-ROM to bypass auto-play

SHIFT+DRAG . . . . . . . . . . . . Move file

SHIFT+F10. . . . . . . . . . . . . . . Opens context menu (same as right-click)

SHIFT+DELETE . . . . . . . . . . . Full wipe delete (bypasses Recycle Bin)

ALT+underlined letter . . . . Opens the corresponding menu

PC Keyboard Shortcuts

Document Cursor Controls

HOME . . . . . . . . . . . . . . to beginning of line or far left of field or screen

END . . . . . . . . . . . . . . . . to end of line, or far right of field or screen

CTRL+HOME . . . . . . . . to the top

CTRL+END . . . . . . . . . . to the bottom

PAGE UP . . . . . . . . . . . . moves document or dialog box up one page

PAGE DOWN . . . . . . . . moves document or dialog down one page

ARROW KEYS . . . . . . . move focus in documents, dialogs, etc.

CTRL+ > . . . . . . . . . . . . next word

CTRL+SHIFT+ > . . . . . . selects word

Windows Explorer Tree Control

Numeric Keypad * . . . Expand all under the current selection

Numeric Keypad + . . . Expands current selection

Numeric Keypad – . . . Collapses current selection

¦ . . . . . . . . . . . . . . . . . . Expand current selection or go to first child

‰ . . . . . . . . . . . . . . . . . . Collapse current selection or go to parent

Special Characters

‘ Opening single quote . . . alt 0145

’ Closing single quote . . . . alt 0146

“ Opening double quote . . . alt 0147

“ Closing double quote. . . . alt 0148

– En dash. . . . . . . . . . . . . . . alt 0150

— Em dash . . . . . . . . . . . . . . alt 0151

… Ellipsis. . . . . . . . . . . . . . . . alt 0133

• Bullet . . . . . . . . . . . . . . . . alt 0149

® Registration Mark . . . . . . . alt 0174

© Copyright . . . . . . . . . . . . . alt 0169

™ Trademark . . . . . . . . . . . . alt 0153

° Degree symbol. . . . . . . . . alt 0176

¢ Cent sign . . . . . . . . . . . . . alt 0162

1⁄4 . . . . . . . . . . . . . . . . . . . . . alt 0188

1⁄2 . . . . . . . . . . . . . . . . . . . . . alt 0189

3⁄4 . . . . . . . . . . . . . . . . . . . . . alt 0190

é . . . . . . . . . . . . . . . alt 0233

É . . . . . . . . . . . . . . . alt 0201

ñ . . . . . . . . . . . . . . . alt 0241

÷ . . . . . . . . . . . . . . . alt 0247

File menu options in current program

Alt + E . . . . . . . . . . . . . . . . . . . Edit options in current program

F1 . . . . . . . . . . . . . . . . . . .  Universal help (for all programs)

Ctrl + A . . . . . . . . . . . . . . . . . . .  Select all text

Ctrl + X . . . . . . . . . . . . . . . . . . .  Cut selected item

Shift + Del  . . . . . . . . . . . . . . . . . . . Cut selected item

Ctrl + C . . . . . . . . . . . . . . . . . . .  Copy selected item

Ctrl + Ins . . . . . . . . . . . . . . . . . . .  Copy selected item

Ctrl + V . . . . . . . . . . . . . . . . . . .  Paste

Shift + Ins  . . . . . . . . . . . . . . . . . . . Paste

Home . . . . . . . . . . . . . . . . . . .  Go to beginning of current line

Ctrl + Home . . . . . . . . . . . . . . . . . . .  Go to beginning of document

End  . . . . . . . . . . . . . . . . . . . Go to end of current line

Ctrl + End  . . . . . . . . . . . . . . . . . . . Go to end of document

Shift + Home  . . . . . . . . . . . . . . . . . . . Highlight from current position to beginning of line

Shift + End  . . . . . . . . . . . . . . . . . . . Highlight from current position to end of line

Ctrl + f  . . . . . . . . . . . . . . . . . . . Move one word to the left at a time

Ctrl + g  . . . . . . . . . . . . . . . . . . . Move one word to the right at a time

MICROSOFT® WINDOWS® SHORTCUT KEYS

Alt + Tab  . . . . . . . . . . . . . . . . . . . Switch between open applications

Alt + Shift + Tab  . . . . . . . . . . . . . . . . . . . Switch backwards between open applications

Alt + Print Screen . . . . . . . . . . . . . . . . . . .  Create screen shot for current program

Ctrl + Alt + Del . . . . . . . . . . . . . . . . . . .  Reboot/Windows® task manager

Ctrl + Esc . . . . . . . . . . . . . . . . . . .  Bring up start menu

Alt + Esc . . . . . . . . . . . . . . . . . . .  Switch between applications on taskbar

F2 . . . . . . . . . . . . . . . . . . .  Rename selected icon

F3 . . . . . . . . . . . . . . . . . . .  Start find from desktop

F4 . . . . . . . . . . . . . . . . . . .  Open the drive selection when browsing

F5 . . . . . . . . . . . . . . . . . . .  Refresh contents

Alt + F4 . . . . . . . . . . . . . . . . . . .  Close current open program

Ctrl + F4 . . . . . . . . . . . . . . . . . . .  Close window in program

Ctrl + Plus Key . . . . . . . . . . . . . . . . . . . Automatically adjust widths of all columns in Windows Explorer

Alt + Enter . . . . . . . . . . . . . . . . . . .  Open properties window of selected icon or program

Shift + F10 . . . . . . . . . . . . . . . . . . .  Simulate right-click on selected item

Shift + Del . . . . . . . . . . . . . . . . . . .  Delete programs/files permanently

Holding Shift During Bootup Boot safe mode or bypass system files

Holding Shift During Bootup When putting in an audio CD, will prevent CD Player from playing

WINKEY SHORTCUTS

WINKEY + D . . . . . . . . . . . . . . . . . . .  Bring desktop to the top of other windows

WINKEY + M . . . . . . . . . . . . . . . . . . .  Minimize all windows

WINKEY + SHIFT + M  . . . . . . . . . . . . . . . . . . . Undo the minimize done by WINKEY + M and WINKEY + D

WINKEY + E . . . . . . . . . . . . . . . . . . .  Open Microsoft Explorer

WINKEY + Tab . . . . . . . . . . . . . . . . . . .  Cycle through open programs on taskbar

WINKEY + F . . . . . . . . . . . . . . . . . . .  Display the Windows® Search/Find feature

WINKEY + CTRL + F . . . . . . . . . . . . . . . . . . .  Display the search for computers window

WINKEY + F1 . . . . . . . . . . . . . . . . . . .  Display the Microsoft® Windows® help

WINKEY + R . . . . . . . . . . . . . . . . . . .  Open the run window

WINKEY + Pause /Break  . . . . . . . . . . . . . . . . . . . Open the system properties window

WINKEY + U . . . . . . . . . . . . . . . . . . .  Open utility manager

WINKEY + L . . . . . . . . . . . . . . . . . . .  Lock the computer (Windows XP® & later)

OUTLOOK® SHORTCUT KEYS

Alt + S . . . . . . . . . . . . . . . . . . .  Send the email

Ctrl + C . . . . . . . . . . . . . . . . . . .  Copy selected text

Ctrl + X . . . . . . . . . . . . . . . . . . .  Cut selected text

Ctrl + P . . . . . . . . . . . . . . . . . . .  Open print dialog box

Ctrl + K . . . . . . . . . . . . . . . . . . .  Complete name/email typed in address bar

Ctrl + B . . . . . . . . . . . . . . . . . . .  Bold highlighted selection

Ctrl + I . . . . . . . . . . . . . . . . . . .  Italicize highlighted selection

Ctrl + U . . . . . . . . . . . . . . . . . . .  Underline highlighted selection

Ctrl + R . . . . . . . . . . . . . . . . . . .  Reply to an email

Ctrl + F . . . . . . . . . . . . . . . . . . .  Forward an email

Ctrl + N . . . . . . . . . . . . . . . . . . .  Create a new email

Ctrl + Shift + A . . . . . . . . . . . . . . . . . . .  Create a new appointment to your calendar

Ctrl + Shift + O . . . . . . . . . . . . . . . . . . .  Open the outbox

Ctrl + Shift + I . . . . . . . . . . . . . . . . . . .  Open the inbox

Ctrl + Shift + K . . . . . . . . . . . . . . . . . . .  Add a new task

Ctrl + Shift + C . . . . . . . . . . . . . . . . . . .  Create a new contact

Ctrl + Shift+ J . . . . . . . . . . . . . . . . . . .  Create a new journal entry

WORD® SHORTCUT KEYS

Ctrl + A . . . . . . . . . . . . . . . . . . .  Select all contents of the page

Ctrl + B . . . . . . . . . . . . . . . . . . .  Bold highlighted selection

Ctrl + C . . . . . . . . . . . . . . . . . . .  Copy selected text

Ctrl + X . . . . . . . . . . . . . . . . . . .  Cut selected text

Ctrl + N . . . . . . . . . . . . . . . . . . .  Open new/blank document

Ctrl + O . . . . . . . . . . . . . . . . . . .  Open options

Ctrl + P . . . . . . . . . . . . . . . . . . .  Open the print window

Ctrl + F . . . . . . . . . . . . . . . . . . .  Open find box

Ctrl + I . . . . . . . . . . . . . . . . . . .  Italicize highlighted selection

Ctrl + K . . . . . . . . . . . . . . . . . . .  Insert link

Ctrl + U . . . . . . . . . . . . . . . . . . .  Underline highlighted selection

Ctrl + V . . . . . . . . . . . . . . . . . . .  Paste

Ctrl + Y . . . . . . . . . . . . . . . . . . .  Redo the last action performed

Ctrl + Z . . . . . . . . . . . . . . . . . . .  Undo last action

Ctrl + G . . . . . . . . . . . . . . . . . . .  Find and replace options

Ctrl + H . . . . . . . . . . . . . . . . . . .  Find and replace options

Ctrl + J . . . . . . . . . . . . . . . . . . .  Justify paragraph alignment

Ctrl + L . . . . . . . . . . . . . . . . . . .  Align selected text or line to the left

Ctrl + Q . . . . . . . . . . . . . . . . . . .  Align selected paragraph to the left

Ctrl + E . . . . . . . . . . . . . . . . . . .  Align selected

©Career Help BD

 15 amazing science facts

1. Babies have around 100 more bones than adults

At birth, Babies have about 300 bones, with cartilage between many of them. This extra flexibility helps them pass through the birth canal and also allows for rapid growth. With age, many of the bones fuse, leaving 206 bones that make up an average adult skeleton.

2. The Eiffel Tower can be 15 cm taller during the summer

When a substance is heated up, its particles move more and it takes up a larger volume – this is known as thermal expansion. Conversely, a drop in temperature causes it to contract again. The mercury level inside a thermometer, for example, rises and falls as the mercury’s volume changes with the ambient temperature. This effect is most dramatic in gases but occurs in liquids and solids such as iron too. For this reason, large structures such as bridges are built with expansion joints which allow them some leeway to expand and contract without causing any damage.

3. 20% of Earth’s oxygen is produced by the Amazon rain-forest

Our atmosphere is made up of roughly 78 per cent nitrogen and 21 per cent oxygen, with various other gases present in small amounts. The vast majority of living organisms on Earth need oxygen to survive, converting it into carbon dioxide as they breathe. Thankfully, plants continually replenish our planet’s oxygen levels through photosynthesis. During this process, carbon dioxide and water are converted into energy, releasing oxygen as a by-product. Covering 5.5 million square kilometres (2.1 million square miles), the Amazon rain-forest cycles a significant proportion of the Earth’s oxygen, absorbing large quantities of carbon dioxide at the same time.

4. Some metals are so reactive that they explode on contact with water

There are certain metals – including potassium, sodium, lithium, rubidium and cesium – that are so reactive that they oxidize (or tarnish) instantly when exposed to air. They can even produce explosions when dropped in water! All elements strive to be chemically stable – in other words, to have a full outer electron shell. To achieve this, metals tend to shed electrons. The alkali metals have only one electron on their outer shell, making them ultra-keen to pass on this unwanted passenger to another element via bonding. As a result they form compounds with other elements so readily that they don’t exist independently in nature.

5. A teaspoonful of neutron star would weigh 6 billion tons

A neutron star is the remnants of a massive star that has run out of fuel. The dying star explodes in a supernova while its core collapses in on itself due to gravity, forming a super-dense neutron star. Astronomers measure the mind-mindbogglingly large masses of stars or galaxies in solar masses, with one solar mass equal to the Sun’s mass (that is, 2 x 1030 kilograms/4.4 x 1030 pounds). Typical neutron stars have a mass of up to three solar masses, which is crammed into a sphere with a radius of approximately ten kilometres (6.2 miles) – resulting in some of the densest matter in the known universe.

6. Hawaii moves 7.5 cm closer to Alaska every year

The Earth’s crust is split into gigantic pieces called tectonic plates. These plates are in constant motion, propelled by currents in the Earth’s upper mantle. Hot, less-dense rock rises before cooling and sinking, giving rise to circular convection currents which act like giant conveyor belts, slowly shifting the tectonic plates above them. Hawaii sits in the middle of the Pacific Plate, which is slowly drifting north-west towards the North American Plate, back to Alaska. The plates’ pace is comparable to the speed at which our fingernails grow.

7. Chalk is made from trillions of microscopic plankton fossils

Tiny single-celled algae called Coccolithophores have lived in Earth’s oceans for 200 million years. Unlike any other marine plant, they surround themselves with minuscule plates of calcite (chocoholics). Just under 100 million years ago, conditions were just right for coccolithophores to accumulate in a thick layer coating ocean floors in a white ooze. As further sediment built up on top, the pressure compressed the coccoliths to form rock, creating chalk deposits such as the white cliffs of Dover. Coccolithophores are just one of many prehistoric species that have been immortalized in fossil form, but how do we know how old they are? Over time, rock forms in horizontal layers, leaving older rocks at the bottom and younger rocks near the top. By studying the type of rock in which a fossil is found paleontologists can roughly guess its age. Carbon dating estimates a fossil’s age more precisely, based on the rate of decay of radioactive elements such as carbon-14.

8. In 2.3 billion years it will be too hot for life to exist on Earth

Over the coming hundreds of millions of years, the Sun will continue to get progressively brighter and hotter. In just over 2 billion years, temperatures will be high enough to evaporate our oceans, making life on Earth impossible. Our planet will become a vast desert similar to Mars today. As it expands into a red giant in the following few billion years, scientists predict that the Sun will finally engulf Earth altogether, spelling the definite end for our planet.

9. Polar bears are nearly undetectable by infrared cameras

Thermal cameras detect the heat lost by a subject as infrared, but polar bears are experts at conserving heat. The bears keep warm due to a thick layer of blubber under the skin. Add to this a dense fur coat and they can endure the chilliest Arctic day.

10. It takes 8 minutes, 19 seconds for light to travel from the Sun to the Earth

In space, light travels at 300,000 kilometres (186,000 miles) per second. Even at this breakneck speed, covering the 150 million odd kilometres (93 million miles) between us and the Sun takes considerable time. And eight minutes is still very little compared to the five and a half hours it takes for the Sun’s light to reach Pluto.

11. If you took out all the empty space in our atoms, the human race could fit in the volume of a sugar cube

The atoms that make up the world around us seem solid but are in fact over 99.99999 per cent empty space. An atom consists of a tiny, dense nucleus surrounded by a cloud of electrons, spread over a proportionately vast area. This is because as well as being particles, electrons act like waves. Electrons can only exist where the crests and troughs of these waves add up correctly. And instead of existing in one point, each electron’s location is spread over a range of probabilities – an orbital. They thus occupy a huge amount of space.

12. Stomach acid is strong enough to dissolve stainless steel

Your stomach digests food thanks to highly corrosive hydrochloric acid with a pH of 2 to 3. This acid also attacks your stomach lining, which protects itself by secreting an alkali bicarbonate solution. The lining still needs to be replaced continually, and it entirely renews itself every four days.

13. The Earth is a giant magnet

Earth’s inner core is a sphere of solid iron, surrounded by liquid iron. Variations in temperature and density create currents in this iron, which in turn produce electrical currents. Lined up by the Earth’s spin, these currents combine to create a magnetic field, used by compass needles worldwide.

14. Venus is the only planet to spin clockwise

Our Solar System started off as a swirling cloud of dust and gas which eventually collapsed into a spinning disc with the Sun at its center. Because of this common origin, all the planets move around the Sun in the same direction and on roughly the same plane. They also all spin in the same direction (counterclockwise if observed from ‘above’) – except Uranus and Venus. Uranus spins on its side, while Venus defiantly spins in the complete opposite direction. The most likely cause of these planetary oddballs are gigantic asteroids which knocked them off course in the distant past.

15. A flea can accelerate faster than the Space Shuttle

A jumping flea reaches dizzying heights of about eight centimetres (three inches) in a millisecond. Acceleration is the change in speed of an object over time, often measured in ‘g’s, with one g equal to the acceleration caused by gravity on Earth (9.8 metres/32.2 feet per square second). Fleas experience 100 g, while the Space Shuttle peaked at around 5 g. The flea’s secret is a stretchy rubber-like protein which allows it to store and release energy like a spring.

Source: how it works daily

Nanotechnology - Only Science 360

Nano-Tech

Definition

A nanometer is a billionth of a meter. Nanotechnology or Nano-tech is manipulation of matter on an atomic, molecular, and supra-molecular scale. The earliest, widespread description of nanotechnology referred to the particular technological goal of precisely manipulating atoms and molecules for fabrication of macro-scale products, also now referred to as molecular nanotechnology. Nano-science and nanotechnology are the study and application of extremely small things and it can be used across all the other science fields, such as biology, chemistry, physics, materials science, and engineering. A more generalized description of nanotechnology was subsequently established by the National Nanotechnology Initiative. Which defined nanotechnology as the manipulation of matter with at least one dimension sized from 1 to 100 nano meters.

How it started?

The ideas and concepts behind Nano-science and Nanotechnology started with a talk entitled “There’s Plenty of Room at the Bottom” by physicist Richard Feynman at an American Physical Society meeting at the California Institute of Technology (CalTech) on December 29, 1959. It was long before the term nanotechnology was used. Feynman described a process in which scientists would be able to manipulate and control individual atoms and molecules.  Over a decade later, Professor Norio Taniguchi coined the term nanotechnology, in his explorations of ultra precision machining. It wasn't until 1981, with the development of the scanning tunneling microscope that could see individual atoms, that modern nanotechnology began.

Aplication of Nano-tech

There are many uses of nano-tech. Nanotechnology is being used in developing countries to help treat disease and prevent health issues and The umbrella term for this kind of nanotechnology is Nano-medicine. Nanotechnology is also being developed for application to a variety of industrial and purification processes. 

Nanoscale surface treatments of fabrics can provide lightweight ballistic energy deflection in personal body armor, or can help them resist wrinkling, staining, and bacterial growth. Clear nanoscale films on eyeglasses, computer and camera displays, windows, and other surfaces can make them water-repellent and residue-repellent, anti-reflective, self-cleaning, resistant to ultraviolet or resistant to infrared light, anti-fog, anti-microbial, scratch-resistant, or electrically conductive.Novel nanoparticles deliver CRISPR gene-editing tools into the cell with much higher efficiency. Transistors, the basic switches that enable all modern computing, have gotten smaller and smaller through nanotechnology. Researchers are investigating carbon nanotube “scrubbers” and membranes to separate carbon dioxide from power plant exhaust.

Source: nano.gov and Wikipedia

The Human Brain -Only Science

The Brain

The brain is an amazing three-pound organ that controls all functions of the body, interprets information from the outside world, and organizes the essence of the mind and soul. A few of the many things governed by the brain are Intelligence, creativity, emotion, and memory. Protected within the skull, the brain is composed of the cerebrum, cerebellum, and brainstem. It is made up of more than 100 billion nerves that communicate in trillions of connections called synapses. 

The brain receives information through five senses: sight, smell, touch, taste, and hearing - often many at one time. It assembles the messages in so that it has meaning for us and can store that information in our memory. The brain controls our thoughts, memory, speech, movement of the arms and legs, and the function of many organs within our body.

The central nervous system-CNS is composed of the brain and spinal cord. The peripheral nervous system-PNS is composed of spinal nerves that branch from the spinal cord and cranial nerves that branch from the brain.

The largest part of the human brain is The cerebrum. The cerebral cortex is an outer layer of grey matter, which covers the core of the white matter. The cortex is split into the neocortex and the much smaller allocortex. The neocortex is made up of six neuronal layers, while the allocortex has three or four neuronal layers. Each hemisphere is conventionally divided into four lobes – the frontal, temporal, parietal, and occipital lobes. The frontal lobe is associated with executive functions including self-control, planning, reasoning, and abstract thought, while the occipital lobe is dedicated to vision. Within each lobe, cortical areas are associated with specific functions, such as the sensory, motor, and association regions. Although the left and right hemispheres are broadly similar in shape and function, some functions are associated with one side, such as language in the left and visual-spatial ability in the right. The hemispheres are connected by commissural nerve tracts, the largest being the corpus callosum.

Facts:

1. The human brain is the largest of all vertebrates in relation to body size.
2. It weighs about 3.3 pounds or 1.5 kilograms.
3. The average male has a brain volume of 1,274 cubic centimeters.
4. The average female brain has a volume of 1,131 cubic centimeters.
5. The brain makes up about 2% of the human body weight.
6. The cerebrum makes up 85% of the brain's weight.
7. It contains about 86 billion nerve cells (neurons).
8. It contains billions of nerve fibers (axons and dendrites).
9. These neurons are connected by trillions of connections or synapses.
10. About 75% of the brain is made up of water. This means that dehydration, even in small amounts, can have a negative effect on the brain functions.
11. The sperm whale's brain is the largest brain In all animals. It weighs about 20 pounds.
12. The human brain will grow three times its size in the first year of life. It continues to grow until you're about 18 years old.
13. It is a myth that humans only use 10 percent of the brain. We actually use all of it. We’re even using more than 10 percent when we sleep.

Source: Wikipedia

LED-Light Emitting Diode- Only Science

LED-Light Emitting Diode

A light-emitting diode (LED) is a semiconductor light source that emits light when current flows through it.

Electrons in the semiconductor recombine with electron holes which releases energy in the form of photons. The color of the light (corresponding to the energy of the photons) is determined by the energy required for electrons to cross the bandgap of the semiconductor. White light is obtained by using multiple semiconductors or a layer of light-emitting phosphor on the semiconductor device. 

Light-emitting diodes came into existence in 1962 which were primarily red in color for the first decade. The first practical LED was invented by Nick Holonyak in 1962 while he was at General Electric.

LED Display:

A LED display is a flat panel display that uses an array of light-emitting diodes as pixels for a video display. The brightness of LED displays allows them to be used outdoors, where they are visible in the sun for store signs and billboards. 

In a LED display many small-sized Light Emitting diodes are placed one after on to create a visual. One red, one, green, and one blue LED is placed as the image above to make a pixel. And thousands of them creates an Image.

Transistor -Only Science

Transistor

A transistor is a semiconductor device used to transmit or switch electrical signals and electrical energy. The word transistor came from two English words "Transfer" and "Resistor". It is composed of semiconductor material usually with at least three terminals for connection to an external circuit. Those three terminals are 1. Collector(C) 2. Base(B) 3. Emitter(E). A current or voltage applied to one pair of the transistor's terminals controls the current through another pair of terminals. Because the controlled (output) power can be higher than the controlling (input) power, a transistor can amplify a signal. Today, some transistors are packaged individually, but many more are found embedded in ICs.


The first working device to be built was a point-contact transistor invented in 1947 by American physicists John Bardeen and Walter Brattain while working under William Shockley at Bell Labs. In 1959, Mohamed Atalla with Dawon Kahng invented the most widely used transistor is the MOSFET (metal-oxide-semiconductor field-effect transistor), also known as the MOS transistor at Bell Labs. The MOSFET was the first truly compact transistor that could be miniaturized and mass-produced for a wide range of uses. Most of the transistors are made from very pure silicon, and some are made from germanium, but certain other semiconductor materials are sometimes used. A transistor may have only one kind of charge carrier, in a field-effect transistor. Or it may have two kinds of charge carriers in bipolar junction transistor devices. Transistors are generally smaller and require less power than the vacuum tube. Certain vacuum tubes have advantages over transistors at very high operating frequencies or high operating voltages. Many types of transistors are made to standardized specifications by multiple manufacturers.

Structure of Transistor

In short, a transistor consists of an area of either p-type or n-type semiconductor sandwiched between regions of oppositely doped silicon. As such devices can be either a PNP or an NPN configuration. There are three connections, the emitter, base, and collector. The base is in the center, bounded by the emitter and collector. The collector is often made larger than the Emitter, as this is where most of the heat is dissipated.

Alloyed junction structure

The alloy junction is another transistor structure that was widely employed in the early days of transistors.

The alloy junction transistor structure used a germanium crystal as the base for the whole structure, as well as being the base connection then the emitter and collector alloy beads were then fused on opposite sides. There were several types of improved alloy-junction transistors developed over the years.

The alloy-junction transistors became obsolete in the early 1960s, with the introduction of the planar transistor. It could be mass-produced easily while alloy-junction transistors had to be made individually.

Diffusion transistors

Unlike the previous transistor structures where the contacts were added to the semiconductor crystal externally, the diffusion transistor enabled the various regions of the transistor to be created by diffusing dopants into the semiconductor crystal to give regions of the required characteristics, p-type, n-type, p+, n+, etc.

The earliest diffusion transistors used a form of the diffused-base transistor structure. These transistors still had alloy emitters and they even sometimes possessed alloy collectors like the earlier alloy-junction transistors. Only the base was diffused into the substrate, although sometimes the substrate formed the collector.

Planar transistor structure

The planar transistor structure was developed at Fairchild Semiconductor in 1959. It represented a major breakthrough in technology. It enabled bipolar transistors to be manufactured more easily, and it also set in place the basis of future integrated circuit technology as well.

The planar transistor structure also includes a passivation layer on the external areas of the crystal. This protects the junction edges from contamination and allows much less expensive plastic packaging to be used without risking degradation transistor performance as a result of contamination entering the crystal lattice, especially in the regions around the junctions.

The lateral planar transistor structure

the current flows in the horizontal plane rather than the vertical plane. This format has advantages in some applications. But it requires more diffusion processes and is, therefore, more complex and hence more expensive. It is only used when performance and characteristics demand it.

Transistor revolutionized the field of electronics and paved the way for smaller and cheaper radios, calculators, and computers, among other things.

(Collected from deferent sources)