Current Affairs 7th Class

    Introduction to UNIX   UNIX is one of the time sharing operating systems primarily intended for program development and document-preparation environment. The first version of UNIX was written by Ten Thompson, later joined by Dennis Ritchie. It was a single user system written for the PDP-7 computer written in assembly language. Several specialized versions of UNIX, such as the programmer's Workbench, UNIX/ PWB and Writer's Workbench, UNIX/WWB are also available.       Some of the major features of UNIX are the following:

• Hierarchical file system.
• Device Independence.
• Multi-user operation.
• Tools and tool-building utilities.
• Probability.    

     

• In 1985 the first version of Windows was released in market.
• iPod, iPhone, and iPad all are developed by Apple.
• Steve Jobs established Apple in April 1976.  

     

• Multiprocessing: It supports in running a program on multiple CPUs.
• Multitasking: Generally it allows more than one program to run at the same time.
• Multi-user: It allows more than one user to run the program at same fraction of time.
• Multithreading: It permits all different modules of a single program to run at the same time.
• Real-Time: Its responds to input immediately.  

     

• The outermost layer of OS is called user interface and innermost layer is hardware. v  OS is a master control program.
• UNIX is one of the time sharing operating systems.
• An OS (Operating System) developed by Tim Peterson of Seattle Computers was refined for the first version of MS-DOS.
• The first version of UNIX was written by Ten Thompson, later joined by Dennis Ritchie.
• The latest version of MS-DOS available in market is 7.x.  

   Introduction to Windows vista   In the series of an operating system, windows launched its new version in comparison to other operating system of windows. Windows Vista is one of the highly security proof operating systems, its basic qualities are the following:

• Organizes files in a new way.
• Searches from within the folders.    
• Keeps devices in synchronized manner.
• Backups and encrypts files.
• Faxes and scans documents.
• Views, edits and organizes pictures.
• Uses improved networking features.
• Provides guidance with parental controls.  

 

     Introduction to Operating System     Operating system is a program which acts as an interface between a computer hardware and a user of the computer. It provides such an environment in which a user may execute programs. Basically there are two goals of an operating system, the primary goal is to make computer system convenient to use and a secondary goal is to use the computer hardware in an effective manner. OS helps in file management, program execution, system management and memory management. The internal structure of operating system is divided into three layers. The outermost layer is called user interface and innermost layer is hardware.                        The following are the main layers in OS:

• Kernel
• Shell
• User Interface  

    Classification of Operating System is the following: 

• Multiprocessing: Supports in running a program on multiple CPUs.
• Multitasking: Allows more than one program to run at the same time.
• Multi - user: Allows more than one user to run the program at same fraction of time.
• Multithreading : Permits all different modules of a single program to run at the same time.
• Real - Time : Responds to input immediately.  

      Microsoft Windows Earlier in Microsoft Windows operating system there was no graphical interface to operate a computer and utilize its resources, user had to know the overall commands with their correct and complete syntax. Regardless of IBM's interest Microsoft continued with development of the GUI. After completion of its development, the new operating system Windows is named by Microsoft and thus in 1985 the first version is released in market.        The following are the lists of various versions of Windows:

• Windows 1.0  
• Windows 2.0
• Windows 3.x
• Windows 95
• Windows 98                              
• Windows 2000
• Windows XP                              
• Windows Vista
• Windows7      

    List of Operating System 

• Windows
• MS-DOS
• LINUX
• UNIX
• MAC  

    Why Operating System is important An operating system is one of the most important features of the system, without operating system we are unable to perform any task on the system. It basically provides the environment within which programs are executed. Since only the operating system can actually perform input/output user programs, it must request all such operations from the operating system.              Windows OS provides GUI and is available in various versions. Which one of the following is the latest version of Windows operating system? (A) more...

     Treatment of Wastewater   Disposal of waste water in water bodies pollutes the water bodies. To cope up with this pollution of water bodies, treatment or cleaning of waste water is done. However, due to increasing population, the more and more sewage is generated and therefore, the cleaning process is not adequately able to handle all the generated waste water.                Treatment of Municipal Waste Water Sewage is carried from sewers to a sewage treatment plant. In the sewage treatment plant, strainers separate large solids such as leaves, rags, plastic, etc.   Then the sewage is passed to settlement tank to settle down the suspended solids to the bottom. The solids settled at the bottom of the settlement tank are called primary sludge. The sludge is used for producing compost and biogas. After this the sewage undergoes secondary treatment. In this, organic matters break down by the action of bacteria. This is done in open tanks called aeration tanks. Aerobic bacteria that needs oxygen act on the sewage in the aeration tanks. Air is blown into these tanks to speed up the process. Sometimes the organic matters in the sewage break down by anaerobic bacteria in closed tanks. The solids get settled at the bottom of tank by the action of bacteria and are called biological or secondary sludge. The sewage can further undergo tertiary treatment before being discharged into water bodies. In this, the sewage passes through sand filters, man-made ponds containing reeds and other organisms that clean out dissolve chemicals.                Wetlands An Alternative and cheaper method of sewage treatment is wetland. In this treatment of sewage bacteria, worms and protozoans act on organic matter. Wetlands also have grasses and reeds that filter pollutants.              In the sewage treatment plant, which one of the following separate large solids such as leaves, rags, plastic, etc? (a) Aeration tank (b) Strainers (c) Sedimentation tank, (d) All of these (e) none of these   Answer: (b)             In which one of the following tanks aerobic bacteria breaks down organic waste present in sewage? (a) Grit and sand removal tank (b) First sedimentation tank (c) Second sedimentation tank (d) Aeration tank (e) none of these   Answer: (d)     Used water is called wastewater. Municipal wastewater comes from homes, offices, etc. and is carried by sewers or sewage pipes. The rain water is also a source of wastewater. Sewage is the liquid waste which contains water dissolved and suspended solid, organic and inorganic more...

        Wastewater   Waste water refers to liquid waste and sewage. In urban areas, this type of waste is carried by sewers or underground pipes. The three main sources of waste water are:                  Municipal Waste Water This is the waste water that comes from homes, offices, etc. and is carried by sewers or sewage pipes. The waste water coming from toilets is referred to as black water and waste water coming from kitchens and bathrooms is called grey water.                 Industrial Waste Water This waste is also referred to as industrial effluent. This kind of waste is not mixed with municipal waste water and disposed separately. One of the most incorrect way of disposing this waste is to allow it to flow into rainwater drains and ultimately into water bodies.                 Rainwater The rainwater flows into rainwater drains in urban areas. The rainwater is carried by underground sewers.  

         Forest – A Natural Habitat   Forest is a natural habitat for animals and micro-organisms. Plants, animals and micro-organisms are dependent on each other in a complex way. Plants and organisms in forests are linked to each other by the process called food chain. In food chain, different plants and organisms are linked to each other by the process of eating and being eaten. The food chain is complex. One organism can be eaten by many other organisms and then each of these organisms can be eaten by many others. This creates a complicated mesh called food web. This complex interlinking indicates that if any one type of plant or animal disappears due to some reason from forest, then the survival of other types of organisms will be endangered.               A dense growth of trees, together with other plants, covering a large area of land is called: (a) Forest (b) Environment (c) Ocean (d) All of these (e) None of these   Answer: (a)             Which One of the following statement is correct? Statement 1: To maintain the environmental balance and to control pollution, deforestation or shrinking of forests should be controlled. Statement 2: To maintain the environmental balance and to control pollution, deforestation or shrinking of forests should not be controlled. (a) Statement 1 (b) Statement 2 (c) Both statements are correct (d) Both statements are incorrect (e) None of these   Answer: (a)     Forest is a dense growth of trees, together with other plants, covering a large area of land. Only about 30% of the world is covered by forest today. Forests are important for maintaining environmental balance. Forests help in controlling rain and temperature. Forests provide habitat to a number of living organisms..

       Forests: Our Lifeline   A forest is a dense growth of trees and various plants, covering a large area of land. It, in fact, is an ecosystem wherein. the community of plants and animals interacting with each other and with the physical environment. However, only about 30% of the world today is covered by forest. Forests are important for maintaining environmental balance and controlling pollution. Forests play the following roles:

• Maintains balance of gases: Forests maintain the balance of carbon dioxide and oxygen, by absorbing carbon dioxide and releasing oxygen.
• Checks pollution: Forests absorb dust and other pollutants. Forests absorb noise and act as barrier against wind.
• Protects soil: The roots of trees bind soil and prevent it from being washed away by rain water or blown by wind. The leaves of tree protect soil from direct rain showers. The leaves that fall and are decomposed make the soil fertile.
• Controls floods and droughts: Forests prevent water from flowing down fast. Thus prevent floods by preventing rivers in the plains from filling up suddenly. This also prevents drought because the water is held by the forests and seeps into the soil and replenishes the groundwater. The availability of groundwater balances the scarcity of water, in particular after monsoon.
• Controls rain and temperature: The process of transpiration releases water vapour from tree leaves that helps to increase rainfall. The evaporation of water from the leaves also causes cooling.

      Deforestation, particularly in the tropical rain forests, has become a major environmental concern, as it can destabilize the earth's temperature, humidity, and carbon dioxide levels. To maintain the environmental balance and to control pollution, deforestation or shrinking of forests should be controlled.

       Weather Forecasting   Weather forecasting is the process in which the observation of the atmosphere of a particular place, in a particular duration is made. Weather at a particular place depends on its atmospheric pressure, speed of wind and temperature. Observation of weather is observed by automatic weather stations or buoys. Weather satellites give the overall coverage of the earth's atmosphere. Radar gives the information about the weather by radiation or IR (infrared). There after it is analyzed in comparison with previously recorded data. Temperature, humidity, rain gauge are the common parameters of weather. A thermometer is used to measure the temperature. Mercury or alcohol inside it expands on heating. Barometer is used to measure air pressure. An increase in the reading of barometer represents sunny and dry weather while falling reading of barometer represents stormy condition. A rain gauge indicates the amount of rain fall within a time period. An anemometer indicates the speed of wind. These all instruments are used to record the weather of a particular place and after analyzing the recorded data weather forecast is made.   Look at the following picture of Stevenson screen In the picture above, a Stevenson screen is shown, which is used for the temperature or humidity measurement of atmosphere. Covers of the Stevenson screen protect it from destructive elements. Holes on the walls allow air passing through it. Stevenson screen is an important measuring instrument in the weather station.                  Weather forecast is partly depended on raw data from measuring instrument and partly from previous recorded data. The raised reading of barometer in the weather forecasting station represents which one of the following? (a) Stormy weather (b) Sunny and dry weather (c) Rain fall (d) All of these (e) None of these   Answer: (b)     The equator of the Earth is at 0° latitude. South Pole is at 90°(S) latitude, and North Pole is at 90°(N) latitude. Weather and climate is effected by atmospheric pressure. Motion of air is due to the uneven heating of the Earth. The layers of atmosphere above the Earth's surface are troposphere, stratosphere, mesosphere, thermosphere, and exosphere. Exerted pressure on the Earth by the atmosphere is called the atmospheric pressure..

         Cyclones   Cyclone is formed naturally over the sea by the heavy and circular, flow of storm. When air of a particular area of upper surface gets heated, it goes upward, thereby creating low pressure area. Air from with high pressure moves to fill the air gap of the low pressure area. If this movement is very fast, it takes the shape of a cyclone. Center of the cyclone is called the eye of the cyclone. The radius of the eye is near about 10 to 30 km. The eye of the cyclone is free from clouds. The strength of the cyclone decreases on moving towards the earth surface.   Look at the following picture of satellite over view of cyclone                    Air blows from north to south is called north wind. The origin of south wind is in which one of the following direction? (a) North (b) East (c) South (d) All of these (e) None of these   Answer: (c)

       Generation of Wind Current   Wind current is generated by the flow of wind from high pressure area to low pressure area. The speed of wind is called wind current. Major pressure belt are subtropical highs, sub polar lows, polar highs and equatorial low. Subtropical highs lie over ocean and develop in summer. The region between 50° and 70° latitude is known as sub polar low. The region of south and north poles is called polar highs. The lack of sunlight causes the high pressure and low current of wind. Equatorial low, called low region due to the low pressure zone, is developed in the presence of heavy amount of solar radiation. Air gets heated around the equator and goes upwards. High pressure region allows flowing air towards low pressure area.               Anemometer An instrument which is used to measure the speed of wind is known as anemometer. The feather like structure, called cups, in front of the anemometer rotates according to the speed of wind. A meter inside it measures the speed of the rotation. The speed of rotation of cups is totally depended on the speed of wind. Slower speed of wind causes the slower rotation of cups and meter inside it reads a low level of flow of wind.   Look at the following picture of anemometer                          Major pressure belts of the earth atmosphere are categorized into which one of the following type? (a) Eight (b) Four (c) Two (d) All of these (e) None of these   Answer: (b)             Sub polar low is between 50° and 70° latitude. Polar high of the earth is located at which one of the following latitude? (a) 30° latitude towards north and south (b) 60° towards north and south (c) 90° towards north and south (d) All of these (e) None of these   Answer: (c)