Touch Screen Systems
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A typical touchscreen input system is basically an input device like a mouse or trackpad. 
What is?
If counting as a definition, A touch screen is a computer display screen that is sensitive to human touch, allowing a user to interact with the computer by touching pictures or words on the screen.
How?
A touchscreen system is made up of a touch sensor, a controller card, and a software driver. 
WHAT ARE TOUCHSCREENS USED FOR?
Touch screens are used with information kiosks, computer-based training devices, and systems designed to help individuals who have difficulty manipulating a mouse or keyboard. Touchscreen systems are being used in a variety of applications, including point-of-sale systems, public information displays, industrial control systems, and more. 
There are a number of types of touch screen technology:
RESISTIVE:
A resistive touch screen panel is composed of several layers. When some object touches this kind of touch panel, the layers are connected at certain point which registers a touch events and sends it to the controller for processing. Resistive touch screen panels are not affected by dust or water and are the type most commonly used today. 
SURFACE ACOUSTIC WAVE:Surface acoustic wave (SAW) technology uses ultrasonic waves that pass over the touch screen panel. When the panel is touched, a portion of the wave is absorbed. This information is sent to the controller for processing.
CAPACITIVE:
A capacitive touch screen panel is coated with indium tin oxide that conducts a continuous electrical current across the sensor. When the sensor’s normal reference state is altered by someone’s finger, electronic circuits measures the resultant ‘distortion’ and informs the controller for processing. Capacitive sensors can either be touch with a bare finger or with a conductive device. Capacitive touch screens are not affected by outside elements and have high clarity.
INFRARED:
This method uses an array of vertical & horizontal IR Sensors that detect the interruption of a modulated light adam near the surface of the screen. InfraRed touch screens are used in many military applications that require a touch panel display.
STRAIN GAUGE:
In this, the screen is spring mounted on the four corners and strain gauges are used to determine deflection when the screen is touched. This technology can also measure the third dimension. This is typically used in exposed public systems such as ticket machines due to their resistance to vandalism. There are several other technologies like Optical imaging, Dispersive Signal Technology, Acoustic Pulse Recognition, Frustrated total internal reflection and Diffused laser imaging.
Related Articles
- Interactive projector that turns any flat surface into a touch screen wins UK design award (gizmag.com)
- Rumor – Apple orders capacitive screens for upcoming touchscreen iMac (edibleapple.com)
- Top 10 Touchscreen Monitors (brighthub.com)
- Hitachi Developing Capacitive Screen that Works with Styli (pocketnow.com)
Particle Physics: Part I – What is Particle Physics?
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Gaurav Happy Tiwari
Presents:
What is Particle Physics?
Particle physics is the study of Particles, from what everything is made of. In this section of Physics we study the fundamental particles that make up all of matter, and their mutual interaction.
Everything around us is made up of these particles, you may say, made up of fundamental building blocks of nature. So, what are these building blocks?
In the early ninteenth century, it was believed that atoms were fundamental; they were thought to be the smallest part of nature and were not made up of anything smaller.
After a sharp progress in Physics, experiments discovered that atoms were not fundamental at all, but were made up of two components:
• Positively charged nucleus
• Negatively charged electrons, surrounding the nucleus.
Then the nucleus was probed to see if it was fundamental, but it too was discovered to be made up of something smaller; positive protons and neutral neutrons bound together with the cloud of electrons still surrounding it.
Now that these protons and neutrons were found, it was time to see if they were fundamental. It was discovered that they were made up of smaller particles called “quarks”, which today are believed to be truly fundamental, along with electrons. Furthermore, electrons belong to a family of fundamental particles, which are called “leptons“. Quarks and leptons, along with the forces that allow them to interact, are arranged in a nice neat theory named The Standard Model
I shall be back soon with second part with much more illustrations & with more resources.
Related Articles
- Bad News For Particle Physics (in the United States) (lockergnome.com)
- The Horror of the Higgs (scienceblogs.com)
Introduction to Universe: Part IV: Black Holes
Image by NASA's Marshall Space Flight Center via Flickr
Black Holes
What are they?
Strange things happen to a star at the end of its life, as it converts to a red giant, black dwarf, white dwarf, supernova etc. (To know more read Part I of this series.)
Consider a star, having its mass is more than 3 times of the mass of the Sun. At the end of its life, it will collapse and will become more and more compact. This collapse will continue until the star becomes so compact and dense that Nothing…Nothing, not even light , would be able to pass through or escape from its gravity. Hence the star will become dark and it cann’t be viewed directly.
Now we say that our Considered Star is A Black Hole.
Nature and More about Black Holes
As of now, our star is a black hole. Now it will emit strong gravitational waves due to its giant mass-density. These waves will be strongest near the black hole and weakest at last approach of the black hole. Thus the shape of black hole’s effect area, will look like Whirl. This is the same as washing machine whirl. . 
Read Part I of this series Here
Introduction to Universe: Part III: Our Sun & Its Structure
Image via Wikipedia
So are you ready to enter into the Sun?
We may divide the internals of the Sun into following major parts:
• Corona
• Chromosphere
• Photosphere
• Solar Envelope
• The Core
Corona
Corona is the outermost part of the sun & you may see it when Full Solar Eclipses occur. The temperature of corona is about 2.7million°C, which is hot enough to emit ultravoilet and X-rays. The corona extends millions of kilometers into space above the photosphere and is very hot- millions of degree celcius.
Chromosphere
In a solar eclipse, a red circle around the outside of the Sun can be seen sometime. This is the chromosphere. The chromosphere is made up of the gases that extend away from the photosphere.Chromosphere is of red color, caused by the abundance of hydrogen. It has a greater (than Photosphere) temperature of about 10000°C. The Chromosphere merges into Corona & Photosphere.
Photosphere
The photosphere is the zone from where the sunlight we see is emitted. The photosphere is a layer of low pressure gasses surrounding the envelope. It is 400 km thick, with a temperature of 4500°C to 6000°C.
The Core:
The innermost layer of the sun is the core with a density of 160g/cm³ (10 times that of lead). The core might be expected to be solid. However, the core’s temperature of 15 million°C keeps it in a gaseous state. In the core, fusion reactions produce energy in the form of γ rays and neutrinos.
From the photosphere of the sun to the chromosphere and to the Corona , the temperature increases, while the same procedure follows up from the photosphere to the core of the sun (I mean temperature increases). Thus you may say in other words that the Photosphere is the COOLEST PLACE in the sun.
Spots in Sun? — SunSpots
The sun has enormous organized magnetic fields that reach from pole to pole. Loops of the magnetic field oppose convection in the convective envelope and stop the flow of energy to the surface. This results in cool spots (i.e. SUNSPOTS) at the surface which produce less light than the warmer part.
Sunspots are dark spots on the photosphere, typically with the same diameter as the Earth.
Sunspots have cooler temperatures than the photosphere. So our thoughts again changes here, that photosphere is the coolest part on the Sun— Now it is the sunspots.
The center of a spot is called the umbra, looks dark gray if heavily filtered & is only 4200°C (as compared to the photosphere at 6000°C).
Penumbra is the portion around the umbra, which looks lighter gray (if filtered).
Sunspots come in cycles, increasing sharply (in numbers) & then decreasing sharply. The period of this solar cycle is about eleven years. The largest spot ever measured (APRIL 1974) covered 18130 million km² i.e., 0.7% of the Sun’s visible surface. The life periods of these spots also vary—from a few hours to many weeks.
Polar Auroras
It is an effect of sunlight.
Polar Auroras are two auroras, the Aurora Borealis or Nothern Lights and the Aurora Australis or Southern Lights. These are lights that sweep across the sky in waves or streamers or folds. They are very often multi-colored and provide one of the finest spectacles in nature. They occur in Arctic and the Antarctic regions respectively. But the Northern lights can be seen as far south as New Orleans in America and the Southern lights as far north as Australia.
Comments and Suggestions are invited from the readers. You may mail me to gaurav.phys@gmail.com
Heterocyclic Compounds
What are Heterocyclic Compounds?
Heterocyclic compounds are cyclic compounds that contain atoms other than carbon in their ring. There are smaller and larger rings and there are also multiple ring heterocycles.
Heterocyclic compounds play a big role in organic chemistry and because they have different electron configurations from carbon, they react differently from carbon rings and differently from each other. For now, it’s simply important to know what a heterocyclic compound is.
Click here to download a file(.PDF)
Introduction to the Universe: Part II: Systems of Stars: Solar System and Our Sun
What does “The Solar System” mean?
The Solar System means the system of the Sun. All bodies under the gravitational influence of our local star, the Sun, together with the Sun, form the Solar System.
Bodies? What kind of bodies?
•The largest bodies, orbiting the Sun, including Earth are called planets.
•Often smaller cool bodies called satellites or moons, orbit a planet.
•Bodies smaller than than the planets that orbit the sun are classed as
asteroids if they are rocky or metallic, comets if they are mostly ice and dust, and meteoroids if they are very small. Most comets release gases as they near the heat of sun, producing a luminous cloud called coma & often a long tail. A meteoroid that burns in Earth’s atmosphere is a meteor, while one that reaches Earth without burning completely becomes a meteorite.
• After the exclusion of Pluto from the planet category, a new category is formed: Dwarf Planet.
Elements of Solar System:
Stars: (1) The Sun
Planets: (8) Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune.
Dwarf Planets: (4) Pluto, Charon, Eris, Ceres- along with the numerous satellites that travels around most of planets.
Others:
Asteroids
Interplanetary Dust
Plasma etc.
What’s Next?
In this article, I shall discuss about the Sun only. Further bodies will be discussed in Part IV & V. While, next Part i.e. PART III, will bring you into the interior of Sun. I suggest you again to read Part I of this Series. 
The Sun
SnapShots & facts about the Sun:
• Sun is one of more than 100 billion stars in the giant spiral galaxy called the Milky Way.
• Sun is the center of the solar system. Its mass is about 740 times as much as that of all the planets combined.
• It continuously gives off energy in several forms- visible light; invisible infrared, ultra-violet, X-rays and γ -rays, cosmic rays, radio waves and plasma.
•The Sun generally move in almost circular orbits around the galactic center at an average speed of about 250 km per second.
•It takes 250 million years to complete one revolution round the center. This period is called a Cosmic Year.
•It’s energy is generated by nuclear fusion in its interior. It is calculated that the Sun consumes about 4million tonnes of hydrogen every second. At this rate, it is expected to burn out its stock of hydrogen in about 5billion years and turn into a red giant.
Solar Statistics
Absolute Visual Magnitude: 4.75
Diameter: 1,384,000 km
Time of one Rotation as seen from the Earth: 25.38days (at equator) to 33days (at poles).
Chemical Composition:
Hydrogen 71%
Helium 26.5%
Other Elements 2.5%
Age: 4.5 billion years aprox.
Expected lifetime: 10 billion years aprox.
Mean distance from Earth 8.2 light seconds i.e. Aprox. 150 million km.
10 Most Endangered Rivers
Image via Wikipedia
The Report from World Wild Fund For Nature lists following Rivers as the most endangered rivers.
1.Salween, Nujiang or Nu River
Location: Shared by China, Myanmar and Thailand. It flows from the Tibetian Plateau.
Major Threat: Dams made on it.
2. La Plata
Location: It crosses five countries in South America. Paraguay, Brazil, Argentina, Uruguay & Bolivia.
Major Threat: Dams and Navigation.
3. Danube
Location: 19 European Countries.
Major Threat: Navigation
4. Rio Grande
Location: Border of US & Mexico.
Major Threat: Water Over-extraction
5. Ganges
Location: India & Bangladesh
Major Threat: Water Over-extraction
6. Murray-Darling
Location: Australia
Major Threat: Invasive Species
7. Indus
Location: China, India, Afganistan and Pakistan
Major Threat: Climate Change
8. Nile
Location: 10 Countries in Africa.
Major Threats: Lowering of Water level
9. Yangtze
Location: Tibet-China
Major Threats: Pollution
10. Mekong
Location: China & Combodia
Major Threat: Over Fishing.
