চাকুরীপ্রার্থী বেকার ভাই বোনেদের প্রতি আমাদের বিনম্র আবেদন……
                          তোমরা আমাদের ভুল বুঝো না , কারন গুলি একটু মন দিয়ে শোন । জানি তোমাদের ধৈর্যের বাঁধ ভেঙ্গে যাচ্ছে তবুও শোন কান খুলে---- দেখো আমাদের নিয়োগ করাতে ইচ্ছা থাকলেও সামর্থ্য নেই…কারনগুলি নিম্নরূপ
১) বিগত সরকারের ঋণ বোঝা মাথায় নিয়ে আমরা সরকার গড়েছি ।
২) সেই ঋণ শোধ করার পাশাপাশি উন্নয়ন করছি সরকারে টিকে থাকার জন্য…তোমরা নিশ্চয় জানো সেই উন্নয়নগুলি কি তথাপি উল্লেখ করি---
ক) ২ টাকা কেজি চাল খাওয়াচ্ছি
খ) সাইকেলে চড়াচ্ছি ছেলে মেয়েদের
গ) থালা গ্লাস , জুতো একবার হলেও বাচ্ছাদের দিয়েছি
ঘ) তোমাদের "বেকার শ্রী" বাদ দিয়ে সব রকম শ্রীপ্রকল্প চালু করেছি
৩) আমাদের হয়ে ভোট করানোর জন্য ক্লাবগুলিকে দেদার টাকা এখনও দিয়ে যাচ্ছি
৪) ইমাম ভ্রাতা সহ মুসলিম ছেলেমেয়েদের অতিরিক্ত স্কলারশিপ দেওয়ার জন্য  মুসলিম তোষন শব্দটিও আমাদের শুনতে হচ্ছে
৫) দলের কর্মীদের খুশিতে রাখতে বিভিন্ন উৎসবের আয়োজন করেছি রাজ্যে ? যেমন মাটী,ঘুঁটে-গোবর,পিঠেপুলি আরো কত কি !
৬) এছাড়া বিভিন্ন দান-খয়রাতি তো আছেই !
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এবার তোমরা যদি প্রশ্ন কর যে, তোমাদের জন্য কি করেছি তবে শোন !……
               নিয়োগ করাবো বলে বিজ্ঞপ্তি দিয়েছি ,যথারীতি পরীক্ষাও নিয়েছি , অনেক মামলা সামলে রেজাল্টও প্রকাশ করেছি ,কিন্তু তোমরা হয়তো একটা জিনিস্ খেয়াল করো নি যে , প্রতি পদক্ষেপে আমরা একটা একটা করে আইনের ফাঁক রেখেছি তোমাদের মামলা করার সুযোগ দেবার জন্য আর আমরা সেই সুযোগকে কাজে লাগিয়ে মামলার অজুহাত দেখিয়ে বছরের পর বছর কাটিয়ে দিয়েছি ! এছাড়া আমাদের উপায় নেই ? কারন ?
  ঐ যে উপরোক্ত উন্নয়নের কথা উল্লেখ করেছি…তা তো আর মুখের কথায় হয় নি ,আর শোন আমরা উন্নয়ন আরও করে যাবো গতিতে বসে থাকার জন্য ! তোমরা কিচ্ছু করতে পারবে না চিৎকার চেঁচামেচি করে কারন রাজ্যে বিরোধী দের আমরা নপুংশক করে রেখেছি !  তোমরা হয়তো কেউ কেউ ভাবছো যে পুরো নিয়োগ প্রক্রিয়াটাই হয়তো আমরা আদালতের সাহায্যে বাতিল করে দেবো …তাই তো ? তাই যদি হয় তোমরা কি করবে ? আমাদের ভোট দেবে না হয়তো কিন্তু জেনে রাখো তা আর দরকার পরবে না ! এমনকি চাকুরীজীবিদেরও না !সেইজন্য তো ওদের ডি এ এবং পে-কমিশন লাগু করা নিয়ে টালবাহানা করে আসছি ! আমাদের সাহস ও আত্মবিশ্বাস এতটাই তাদের প্রতি যারা আমাদের সরকারে আবার রেখে দেবে, আমাদের উন্নয়নের ফল ভোগ করে… আর এই সংখ্যাটাই বেশি ! তাই তোমাদের ওতো তোয়াক্কা করি না !
তোমরা কি জানো নিয়োগ করলে কত লক্ষ লক্ষ না হলেও হাজার হাজার কোটি টাকা খরচ হবে সরকারের ? পাবো কোথায় ওতো টাকা ? এখন তো আর সুদীপ্ত সেনের মত রাঘব-বোয়াল গুলো নেই ! তোমাদের মত পড়াশুনা করা মধ্যবিত্ত ছেলেমেয়েদের কাছে টাকাও তো চাইতে পারবো না ! যাদের চাকরি দিয়েছি তাদের বেশির ভাগই আমাদের তা অগ্রীম মোটা টাকা দিয়েছে তোমরা যেটাকে বলে থাকো " ঘুষ"!
   অতএব, স্নেহের ভাইবোনেরা আমাদের ভুল বোঝো না , নতুন করে নিয়োগ বিজ্ঞপ্তি আমরা আবারও তৈরী করছি…লোকসভা ভোট উপলক্ষে তার আগে তোমরা না হয় চপ টপ ভাজা শুরু করে দাও । ভাল থেকো নিজেদের দুর্বল ভেবো না …এটা আমাদের কথা না স্বয়ং স্বামীজী বলে গেছেন ! আর কি বলবো উন্নয়ন চলছে _মামলার পাশাপাশি সরকারও চলছে !

Computers for Organisations

Computers for Organisations:

Some computers handle the needs of many users at the same time. These powerful systems are most often used by organizations, such as businesses or schools, and are commonly found at the heart of the organization‘s network. . Generally, each user interacts with the centralized computer through his or her own devrce (generally desktop computer), freeing people from having to wait their turn at a Single

keyboard and monitor. The largest organizational computers support thousands 0f individual users at the same time, from thousands of miles away.

The four primary types of computers in this category are

Network Servers

Mainframe Computers 

Minicomputers

Supercomputers 

Network Servers:

Today, most organisations' networks are based on personal computers. Individual users have their own desktop computers, which are connected to one or more centralised computers, called network servers. A network server is usually a powerful personal computer with special software and equipment that enable it to function as the primary computer in the network

PC-based networks and sewers offer companies a great deal of flexibility. A PC-based server gives users flexibility to do different kinds of tasks. For example, some users may rely on the server for e-mail access, some may use it to perform accounting tasks, and others may use it to perform word-processing or database-management jobs. The server can support these processes, and many others, while storing information and programs for many people to use.

Mainframe Computers:

Mainframe computers are used in large organisations such as insurance companies and banks, where many peOple frequently need to use the same data. in a traditional mainframe environment, each user accesses the mainframe's resources

through a device called a terminal. There are two kinds of terminals. A dumb terminal does not process or store data; it is simply an input/output (l/O) device that functions as a window  into a computer located somewhere else. An intelligent
terminal can perform some processing operations, but it I usually does not have any storage. In some mainframe
environments, however, workers can use a standard personal  Mainframe computer to access the mainframe. Computer

Mainframes are large, powerful systems  The largest mainframes can handle the processing needs of thousands of users at any given moment. But what these systems offer in power, they lack in flexibility. Most mainframe systems are designed to handle only a specific set of tasks. In your state's Department of Motor Vehicles, for example, a mainframe system is probably devoted to storing information about drivers, vehicles, and driver's licenses, but little or nothing else. By limiting the number of tasks the system must perform, ' administrators preserve as much power as possible for required operations.

You may have interacted with a mainframe system without even

knowing it. For example, if you have ever visited an airline’s :Web site to reserve a seat on a flight, you probably conducted a transactions with a mainframe computer

Minicomputers:

First released in the 19603, minicomputers got their name because of their small size compared to other computers of the day. The capabilities of a minicomputer are somewhere between those of mainframes and personal computers. For this reason, minicomputers are often called midrange computers like mainframes, minicomputers can handle much more input and output than personal computers can. 

Supercomputers:

supercomputers are the most powerful computers made, and physically they are some of the largest . These systems can process huge amounts of data, and the fastest supercomputers can perform more than one trillion calculations per second. Supercomputers can house thousands of processors and ideal for handaling large and highly complex problems that 

Computer for individual users

Computers for Individual Users

Most computers are meant to be used by only one person at a time. Such computers are often

shared by several people (such as those 1n our centre' s computer lab), but only one user can work with the machine at any given moment.

The six primary types of computers in this category are
* Desktop computers
* Workstations
* Notebook computers
* Tablet computers
* Handheld computers
* Smart phones

Introduction to Computers

Desktop computers :
The most common type of personal computer is the desktop computer-a PC that  designed to sit on (or under) a desk or table. These are the systems you see all around you, in schools, homes, and offices, and they are the main focus of this material

Today's desktop computers are far more powerful than those of just a few years ago, and are used for an amazing array of tasks. Not only do these machines enable people to do theirjobs with greater ease and efficiency, but they can be used to communicate, produce music, edit photographs and videos, play sophisticated games, and much more.

Workstations:
A workstation is a specialized; single-user computer that typically c has more power and features than a standard desktop PC . These machines are popular among scientists, engineers, and

animators who need a system with greater-than-average speed and the power to perform sophisticated tasks. Workstations often have m large, high-resolution monitors and accelerated graphics-handling capabilities, making them suitable for advanced architectural or engineering design, modeling, animation, and video editing. Note that due to rapid technological advancement, the difference between desktop and workstation are very thin or almost invisible.

Notebook Computers:
Notebook computers, as their name implies, approximate the shape of an 8.5-by inch notebook and easily lit inside a briefcase. Because people frequently set these devices on their lap, they are also called laptop computers.
Notebook  computers can operate on alternating current or special batteries. These amazing devices generally weigh less than eight pounds, and some even weigh less than three pounds!

use, the computer's lid is raised to reveal a thin monitor and a keyboard. When not in use, the device folds up for easy storage. Notebooks are fully functional microcomputers; people who use them need the power of a full-size desktop computer wherever they go  Because of their portability, notebook PCs fall into a category of devices called mobile computers-systems small enough to be carried by their user. 

Tablet PCs:

The tablet PC is the newest development in portable, full-featured computers. Tablet PCs offer all the functionality of a notebook PC, but they are lighter and can accept input from a . special pen-called a stylus or a digital pen-that is used to tap or who directly on the screen. Many tablet PCs also have a built-in

microphone and special software that accepts input from the user’s voice.

Handheld PCs:
Handheld personal computers are computing devices small enough to fit in your hand . A popular type of handheld computer is the personal digital assistant (PDA). A PDA is no larger than a small appointment book and is 'normally used for special applications, such as taking notes, displaying telephone numbers and addresses, and keeping track of dates or agendas. Many PDAs let the user access the Internet through a wireless

connection, and several models offer features such as cellular telephones, cameras, music players, and global positioning systems.

Smart Phones:
Some cellular phones double as miniature PCs . Because these phones offer advanced features not typically found in cellular phones, they are sometimes called smart phones. These features can include Web and e-mail access, special software such as personal organisers, or special hardware such as digital cameras or music players. Some models even break in half to reveal a miniature keyboard.

Characteristics of Computer

Speed: Computers can access information and process in fractions of less than a millionth of a second. They are very fast in doing calculations. The processing speed is usually measured in MIPS (millions of instruction per second).

Memory Capacity: Computers have more memory capacity in order to store large volumes of data, information and instructions and to retrieve that information whenever required.

Accuracy: Computer solves any typical problem with high accuracy. If an error occurs it may be only due to human mistakes, which is quite common.

Diligence: Computers can work for hours together which is not possible with humans because of fatigue. So working of computers is not a time-constraint.

Repetitiveness: Computers have the capacity to repeat any operation any number of times. This makes any work to be completed in a short span of time.

Reliability: computer possesses high reliability in all its activities. It can produce fast and accurate results whenever operated, at any instance for any number of times.

Endurance: endurance indicates lifetime of the computer system. Though computers can perform any function repeatedly any number of times they do not show any weakness after serving a certain period of time

Versatility. the computer is so versatile that it can be connected to any internal or external device. This characteristic makes the computer to control any device that is connected to it.

Plate Tectonic

Plate Tectonic
a theory explaining the structure of the earth's crust and many associated phenomena as resulting from the interaction of rigid lithospheric plates which move slowly over the underlying mantle.


Types

Three types of plate boundaries exist, with a fourth, mixed type, characterized by the way the plates move relative to each other. They are associated with different types of surface phenomena. The different types of plate boundaries are^.

Transform boundaries (Conservative) occur where two lithospheric plates slide, or perhaps more accurately, grind past each other along transform faults, where plates are neither created nor destroyed. The relative motion of the two plates is either sinistral (left side toward the observer) or dextral (right side toward the observer). Transform faults occur across a spreading center. Strong earthquakes can occur along a fault. The San Andreas Fault in California is an example of a transform boundary exhibiting dextral motion.

Transform boundaries

Divergent boundaries (Constructive) occur where two plates slide apart from each other. At zones of ocean-to-ocean rifting, divergent boundaries form by seafloor spreading, allowing for the formation of new ocean basin. As the continent splits, the ridge forms at the spreading center, the ocean basin expands, and finally, the plate area increases causing many small volcanoes and/or shallow earthquakes. At zones of continent-to-continent rifting, divergent boundaries may cause new ocean basin to form as the continent splits, spreads, the central rift collapses, and ocean fills the basin. Active zones of Mid-ocean ridges (e.g., Mid-Atlantic Ridge and East Pacific Rise), and continent-to-continent rifting (such as Africa's East African Rift and Valley, Red Sea) are examples of divergent boundaries.

Divergent boundaries

Convergent boundaries (Destructive) (or active margins) occur where two plates slide toward each other to form either a subduction zone (one plate moving underneath the other) or a continental collision. At zones of ocean-to-continent subduction (e.g. the Andes mountain range in South America, and the Cascade Mountains in Western United States), the dense oceanic lithosphere plunges beneath the less dense continent. Earthquakes trace the path of the downward-moving plate as it descends into asthenosphere, a trench forms, and as the subducted plate is heated it releases volatiles, mostly water from hydrous minerals, into the surrounding mantle. The addition of water lowers the melting point of the mantle material above the subducting slab, causing it to melt. The magma that results typically leads to volcanism.^[13] At zones of ocean-to-ocean subduction (e.g. Aleutian islands, Mariana Islands, and the Japanese island arc), older, cooler, denser crust slips beneath less dense crust. This causes earthquakes and a deep trench to form in an arc shape. The upper mantle of the subducted plate then heats and magma rises to form curving chains of volcanic islands. Deep marine trenches are typically associated with subduction zones, and the basins that develop along the active boundary are often called "foreland basins". Closure of ocean basins can occur at continent-to-continent boundaries (e.g., Himalayas and Alps): collision between masses of granitic continental lithosphere; neither mass is subducted; plate edges are compressed, folded, uplifted.

Convergent boundaries

Plate boundary zones occur where the effects of the interactions are unclear, and the boundaries, usually occurring along a broad belt, are not well defined and may show various types of movements in different episodes.
 

Continental Drift

In 1915, the German geologist and meteorologist Alfred Wegener first proposed the theory of continental drift, which states that parts of the Earth's crust slowly drift atop a liquid core. The fossil record supports and gives credence to the theories of continental drift and plate tectonics.

Continental Drift

Plate Movement force

gravity anomaly

gravity anomaly
                                              A gravity anomaly is the difference between the observed acceleration of a planet's reaction to gravity and a value predicted from a model. A location with a positive anomaly exhibits more gravity than predicted, while a negative anomaly exhibits a lower value than predicted.
   

Gravity Anomalies and Interpretation

Isostasy

Isostasy

Isostasy (Greek ísos "equal", stásis "standstill") is the state of gravitational equilibrium between Earth's crust and mantle such that the crust "floats" at an elevation that depends on its thickness and density of underlying roots of the low density of the mountain.
This concept is invoked to explain how different topographic heights can exist at Earth's surface. When a certain area of Earth's crust reaches the state of isostasy, it is said to be in isostatic equilibrium. Isostasy does not upset equilibrium but instead restores it (a negative feedback). It is generally accepted  that Earth is a dynamic system that responds to loads in many different ways. However, isostasy provides an important 'view' of the processes that are happening in areas that are experiencing vertical movement. Certain areas (such as the Himalayas) are not in isostatic equilibrium, which has forced researchers to identify other reasons to explain their topographic heights (in the case of the Himalayas, which are still rising, by proposing that their elevation is being "propped-up" by the force of the impacting Indian plate; the Basin and Range Province of the Western US is another example of a region not in isostatic equilibrium.)
Although originally defined in terms of continental crust and mantle, it has subsequently been interpreted in terms of lithosphere and asthenosphere, particularly with respect to oceanic island volcanoes such as the Hawaiian Islands.
In the simplest example, isostasy is the principle of buoyancy wherein an object immersed in a fluid is buoyed with a force equal to the weight of the displaced fluid. On a geological scale, isostasy can be observed where Earth's strong crust or lithosphere exerts stress on the weaker mantle or asthenosphere, which, over geological time, flows laterally such that the load is accommodated by height adjustments.
The general term 'isostasy' was coined in the year 1889 by the American geologist Clarence Dutton.

 Airy and Pratt

Airy & Pratt's Model 

 

 

 

 

 

 

 Which One is Correct ???



 


 Depth of  Compensation

Depth of Compensation

Geography

  Geography (from Greek γεωγραφία, geographia, literally "earth description") is a field of science devoted to the study of the lands, the features, the inhabitants, and the phenomena of Earth.

The first person to use the word "γεωγραφία" was Eratosthenes (276–194 BC). 

Four historical traditions in geographical research are spatial analysis of the natural and the human phenomena (geography as the study of distribution), area studies (places and regions), study of the human-land relationship, and research in the Earth sciences. 

Nonetheless, modern geography is an all-encompassing discipline that foremost seeks to understand the Earth and all of its human and natural complexities—not merely where objects are, but how they have changed and come to be.

 Geography has been called "the world discipline" and "the bridge between the human and the physical science". Geography is divided into two main branches:  

physical geography

 and 

human geography.

Seismic Waves

Seismic waves are the waves of energy caused by the sudden breaking of rock within the earth or an explosion. They are the energy that travels through the earth and is recorded on seismographs. Types of Seismic Waves. There are several different kinds of seismic waves, and they all move in different ways.

Main Types of Seismic Wave

Way of Traveling 

            
 Shadow zone

 A seismic shadow zone is an area of the Earth's surface where seismographs cannot detect an earthquake after its seismic waves have passed through the Earth.

Shadow Zone

                  Extra data is been given for extra knowledge

Types of seismic waves and characteristics

The structure of Earth

Structure, Depth, Parts 

1)    The Crust : mainly SiAl (Silica + Aluminium)

·       Outermost solid part of the earth., brittle in nature

·       Thickness of crust more at continental areas (it is around 30 Kms) than at oceanic areas (where it is around 5 km).

·       At major mountains, thickness is as high as 70 Kms.

·       Rock density is around 3 g/cm³ in continent areas.

·       At oceanic area, rock is mainly basalt with density around 2.7 g/cm^3.

2)    Mantle: mainly SiMa (Silica + Magnesium)

·       Portion of interior beyond crust.

·       Extends from Moho’s discontinuity to depth of 2900 Kms.

·       Upper portion of Mantle is called asthenosphere (astheno means weak) – depth upto 400 Kms; main source of magma; density (3.4 g/cm³ ) more than crust.

·       Crust + upper mantle = lithosphere (its thickness ranges from 10-200 km).

·       Lower Mantle – beyond asthenosphere and is in solid state.

3)    The Core: mainly NiFe (Nickel + Iron)

·       Core-Mantle boundary located at 2900 km depth.

·       Outer core is in liquid state while inner in solid state.

·       Density at core mantle boundary is around 5g/cm³ & at centre is around 13g/cm³

^{There are zone of separation also known as discontinuities between above layers (i.e. Core, Mantle and Core) which are as under:}

 

All Discontinuity