carbon cycle

Carbon is an element found in all forms of life. Carbon makes up 18 percent of our bodies and is a 

major component of trees and plants. It also exists in the environment in non-living things like rocks, oil, 

natural gas, coal, and air. In short, it is the basic building block of all life and the environment we 

live in. Carbon, in its many forms, is exchanged among the atmosphere, oceans, and land. This is called the 

carbon cycle (see Fig. 1).  In simple terms, plants take carbon dioxide (CO2) from the atmosphere and 

turn it into biomass (wood, leaves, fruits etc.)  process called “photosynthesis.” Some of the 

carbon taken in by plants is returned to the atmosphere through respiration by the plant or by

other living organisms, including humans, that use it for food or fuel.  This renews the carbon cycle.  By

extracting fossil fuels (oil, gas and coal) from deep in the Earth, we are overloading the atmosphere with carbon, and changing our climate in irreversible ways.

One critical part of the carbon cycle takes place in forests. Forests exchange large amounts of CO2 and other gases with the atmosphere and store carbon, in various forms, in trees and soils. Carbon stored in plants or soils is called “sequestered carbon.” Carbon returned to the atmosphere when it has been used by trees or other organisms as energy for life is called “respired carbon.” If we follow the fate of carbon in a forest, many processes are occurring .Much of the CO2 in the air above a forest is taken in by trees through the process of photosynthesis, where it becomes one of the building blocks for tree growth or energy for life.Some carbon goes right back into the atmosphere as the tree respires (breathes out); but, if it stays, then it may remain sequestered in the tree throughout its life—whether that is 10 or 500 years.  

The Earth’s climate is changing.  In the past, the climate warmed and cooled due to natural processes.  Now
humans are changing the climate by burning fossil fuels and permanently deforesting landscapes. Many of our
wildlands are being stressed beyond their natural ability to adapt to these dramatic changes, and the full extent
of how to deal with these changes remains unclear.
What is clear, however, is that a better understanding of the carbon cycle and the role forests play will
help us better manage forests and fire in a future marked by climate change. When a tree dies or loses a leaf or branch containing carbon, it generally falls to the forest floor where it will be decomposed by bacteria and fungi, and either be respired back into the atmosphere or made into soil carbon. Carbon is returned daily to
the atmosphere when it is decomposed and respired by soil organisms. But, much of it remains in complex chemical forms that resist decomposition and persist for hundreds to thousands of years. Soil carbon is an important carbon storehouse. It accounts for as much carbon as is presently found in plants and the atmosphere combined.Fire plays an important role in the forest carbon cycle. When a fire occurs, a portion of the trees, plants, grasses and other biomass are consumed and converted to CO2 and other gases, and another portion is converted to charcoal, an essentially permanent form of storage. Only 10 to 30 percent of the biomass in a forest is actually consumed by a fire; the majority remains on-site. Live trees will continue their role in the carbon cycle. Dead trees will slowly decompose and release carbon to the atmosphere or make new soil carbon. Regrowth after a fire will recapture carbon from the atmosphere, reversing the fire’s emissions. About one to 10 percent of biomass killed in a fire is converted to charcoal, a uniquely stable form of carbon that will persist for thousands of years.

Until humans began burning fossil fuels, the carbon cycle was closed to new inputs of carbon and carbon was
continually recycled. Earth’s plants and animals evolved over thousands of years under this level of CO2 and a slowly changing climate, creating the forest ecosystems we know today. Now we are extracting billions of tons of fossil fuels each year to meet the energy demands of a growing global population, adding new carbon to the atmosphere and changing our climate. Prior to fossil fuel use, this carbon was locked underground for millions of years and was not part of the carbon cycle. Current levels of CO2 are 25 percent higher than before the Industrial Revolution. As a result of these elevated levels of carbon, our forest ecosystems are changing. They are changing the way they grow in response to elevated CO2, and they are changing in response to new climate patterns, including warmer temperatures and different levels of precipitation. These changes also affect the way that they store and release carbon, sometimes reducing the amount that goes into tree carbon or soil carbon.

The Discovery of Radioactivity

In 1896 Henri Becquerel was  using  naturally  fluorescent minerals to  study  the properties  of  x-rays, which  had  been  discovered  in  1895  by  Wilhelm  Roentgen.  He exposed potassium uranyl sulfate to sunlight and then placed it  on  photographic  plates wrapped in black paper, believing that the uranium absorbed the sun’s energy and then emitted it as x-rays. This hypothesis was disproved on the 26t h-27t h of February, when his experiment “failed” because it was overcast in Paris. For  some reason, Becquerel decided to develop his photographic plates anyway. To  his  surprise, the images were strong  and

clear, proving that the uranium emitted radiation without an external source of energy such as the sun. Becquerel had discovered radioactivity.

Becquerel used an apparatus similar to  show  that  the radiation he discovered could  not  be  x-rays.  X-rays are  neutral and  cannot be  bent in  a magnetic field. The new radiation was bent by the magnetic field so that the radiation must be charged and different than x-rays. When different radioactive substances were put in the magnetic field, they deflected in different directions or not at all, showing that there were three classes of radioactivity: negative, positive, and electrically neutral.

The term radioactivity was actually coined by Marie Curie, who together with her husband Pierre, began investigating the phenomenon recently discovered by Becquerel. The Curies extracted uranium from ore and to their surprise, found that the leftover ore showed more activity than the pure uranium. They concluded that the ore contained other radioactive elements. This led to the  discoveries of  the elements polonium and  radium. It took  four more years of processing tons of ore to isolate enough of each element to determine their
chemical properties.



Ernest Rutherford, who did many experiments studying the properties of radioactive decay, named these alpha, beta, and gamma particles, and classified them by their ability to penetrate matter. Rutherford used an apparatus similar to that depicted in Fig.  3-7. When the air from the chamber was removed, the alpha source made a spot on the photographic plate. When air was added, the spot disappeared. Thus, only a few centimeters of air were
enough to stop the alpha radiation.

Because alpha particles carry more electric charge,  are  more  massive, and  move slowly compared to beta and gamma particles, they interact much more easily with matter. Beta particles are much less massive and move  faster, but  are  still electrically charged. A sheet of aluminum one-millimeter thick or several meters of air will stop these electrons and positrons. Because gamma rays carry no electric charge, they can penetrate large distances through materials before interacting—several centimeters of lead or a meter of concrete is needed to stop most gamma rays.

Gamma Decay

In gamma decay,  a nucleus changes from a higher energy state to a lower energy state through the emission of  electromagnetic radiation (photons). The number of protons (and neutrons) in the nucleus does not  change in this  process, so  the parent and daughter atoms  are  the  same  chemical element.  In  the  gamma  decay  of  a nucleus, the emitted photon and recoiling nucleus each have a well-defined energy after the decay. The characteristic energy is divided between only two particles.

Beta Decay

Beta particles are electrons or positrons (electrons with positive electric charge, or antielectrons). Beta decay occurs when, in a nucleus with too many protons  or  too many neutrons, one of the protons or neutrons is transformed into the other. In beta minus decay, a neutron decays into a proton, an electron, and an antineutrino: n Æ
p + e
-
+—
n   .  In  beta plus  decay, shown in  Fig.  3-5b, a  proton  decays into a  neutron, a
positron, and a neutrino: p Æ n + e
+
+n. Both reactions occur because in different regions of the Chart of the Nuclides, one or the other will move the product closer to the region of
stability. These particular reactions  take  place  because  conservation laws  are  obeyed.
Electric charge conservation requires that if an electrically  neutral  neutron  becomes  a positively charged proton, an electrically negative particle (in this  case, an  electron) must also be produced. Similarly, conservation of lepton number requires that if a neutron (lepton number = 0) decays into a proton (lepton number = 0) and an electron (lepton number =  1), a particle with a lepton number of -1 (in this case an antineutrino) must also be produced.
The leptons emitted in beta decay did not exist in the nucleus before the  decay—they are created at the instant of the decay.

















     








To the best of our knowledge, an isolated proton,  a  hydrogen  nucleus  with  or without an electron, does not decay. However within a nucleus, the beta decay process can change a proton to a neutron. An isolated neutron is unstable and will decay with a half-life of 10.5 minutes. A neutron in a nucleus will decay if a more stable nucleus results; the halflife of the decay depends on the isotope. If it leads to a more stable nucleus, a proton in a nucleus may capture an electron from the atom (electron capture), and change into a neutron and a neutrino.


Proton decay, neutron decay, and electron capture are three ways in which protons can be changed into neutrons or vice-versa; in each decay there is a change in the atomic number, so that the parent and daughter atoms are different elements. In all three processes, the number A of  nucleons  remains the  same, while both  proton  number, Z, and  neutron
number, N, increase or decrease by 1.
In beta decay the change in binding energy appears as the mass energy and kinetic energy of the beta particle, the energy of the neutrino, and the kinetic energy of the recoiling daughter nucleus. The energy of an emitted beta particle from a particular decay can take on a range of values because the energy can be shared in many ways among the three particles while still obeying energy and momentum conservation.

Alpha Decay

In alpha decay the  nucleus  emits  a He  nucleus, an  alpha particle. Alpha decay occurs most often in massive nuclei that have too large a  proton to neutron ratio. An alpha particle, with its two protons and two neutrons, is a very  stable configuration of particles. Alpha radiation reduces the ratio of  protons to  neutrons in the parent nucleus, bringing it to a more stable configuration. Nuclei, which are more massive than lead, frequently decay by this method.




Consider the example of 
2 1 0
Po decaying by the emission of an alpha  particle. The
reaction can be written 
2 1 0
Po Æ
2 0 6
Pb  + 
4
He. This polonium nucleus has 84 protons  and
126 neutrons. The ratio of protons to neutrons is Z/N =  84/126, or 0.667. A 
2 0 6
Pb  nucleus
has 82 protons and 124 neutrons, which gives a  ratio  of  82/124,  or  0.661.  This  small
change in the Z/N ratio is enough to put the nucleus into a more stable state, and as shown
in Fig. 3-4, brings the “daughter”  nucleus (decay product) into the region of stable nuclei
in the Chart of the Nuclides.
In alpha decay, the atomic number changes, so the original (or parent) atoms and the
decay-product  (or  daughter) atoms are  different elements and  therefore  have  different
chemical properties.










In the alpha decay of a nucleus, the change in binding energy appears as the kinetic
energy of the alpha particle and the daughter nucleus. Because this energy must be shared
between these two particles, and because the alpha particle and daughter nucleus must have
equal and opposite momenta, the emitted alpha particle and recoiling nucleus will each have
a well-defined energy after the decay. Because of its smaller mass,  most  of  the  kinetic
energy goes to the alpha particle.

Radioactivity

In radioactive processes, particles or electromagnetic radiation are emitted from the
nucleus. The most common forms of radiation emitted have been traditionally classified as
alpha (a), beta (b),  and  gamma  (g )  radiation. Nuclear  radiation occurs  in  other  forms,
including the emission of protons or neutrons or spontaneous fission of a massive nucleus.
Of the nuclei found on Earth, the vast majority is stable. This is so  because almost
all short-lived radioactive nuclei have decayed during the  history  of  the Earth. There are
approximately 270 stable isotopes and 50 naturally occurring  radioisotopes (radioactive
isotopes). Thousands of other radioisotopes have been made in the laboratory.











Radioactive decay will change one nucleus to another if the product nucleus has  a
greater nuclear binding energy than the initial decaying nucleus. The difference in binding
energy (comparing the before and after states) determines which decays are energetically
possible and which are not. The excess binding energy appears as  kinetic energy  or  rest
mass energy of the decay products

The Chart of the Nuclides, is a plot of nuclei as a function  of  proton  number,  Z,  and  neutron  number,  N .  All  stable  nuclei  and  known radioactive nuclei, both naturally occurring and manmade, are  shown  on  this  chart, along with their decay properties. Nuclei with an  excess  of  protons  or  neutrons in  comparison

with the stable nuclei will decay toward the stable nuclei by changing protons into neutrons

or neutrons into protons,  or  else  by  shedding  neutrons  or  protons  either  singly  or  in

combination. Nuclei are also unstable if they are excited, that is, not in their lowest energy

states.  In this case  the  nucleus  can  decay  by  getting  rid  of  its  excess  energy  without

changing Z or N by emitting a gamma ray.

Nuclear decay processes must  satisfy  several conservation laws, meaning that the

value of the conserved quantity after the decay, taking into account all the decay products,

must  equal the  same  quantity  evaluated  for the  nucleus  before  the  decay.  Conserved

quantities include  total  energy  (including  mass),  electric  charge,  linear  and  angular

momentum, number of nucleons, and lepton number (sum  of  the  number  of  electrons,

neutrinos, positrons and antineutrinos—with antiparticles counting.

The number of nuclei in a sample that will decay in a  given interval of  time is
proportional to the number of nuclei in the sample. This condition leads to radioactive decay
showing itself as an exponential process, as shown in Fig. 3-2. The number,  N,  of  the
original nuclei remaining after a time t from an original sample of N0
 nuclei is
N = N0
e
-(t/T)
where T is the mean lifetime of the parent nuclei. From this relation, it can be shown that t1 / 2
= 0.693T.

VISCOCITY

Viscosity is the resistance to flow the liquid.All liquid show some viscosity.Some liquid have high resistance to the flow the liquid.

Such liquid is said to have high viscosity.For example glycerin which flows slowly is said to have high viscosity.Water and alcohol flow readily and said to have low viscosity.Viscosity is due to the intermolecular force of attraction between the liquid  molecules. The greater the intermolecular forces the greater will be the viscosity of liquid.When a fluid is subjected to external forces, it resists flow due to internal molecular friction, Viscosity is a measure of that internal friction.   Viscosity can be referred to as the measurement of a fluid’s resistance to flow.   Viscosity can be viewed in two different ways.   The first is a fluid’s tendency to flow as is visually indicated.   One can think of this as the time it takes to watch a fluid pour out of a container.   The term used to describe this is Kinematic Viscosity and it is expressed in units indicating flow volume over a period of time.   The most commonly used unit of Kinematic Viscosity is the centistoke.

In order to understand, why different liquid flow with different speed, consider the flow of liquid through a narrow tube or pipe.
We can imagine that the liquid flowing through a tube consists of a large number of concentric molecular layers.A thin layer in immediate
with the wall of tube is almost stationary.Then each succeeding layer moves with gradually increasing speed which becomes maximum at
the centre.
The internal friction or resistance that one layer of a liquid moving with the certain viscosity offers to another adjacent layer moving with a different velocity is called the viscosity of liquid.

PHENOMENON OF CAPILLARY ACTION

  

 Capillary action is very important in nature, particularly in the transport of fluids in plants and through the soil.

An effect due to intermolecular forces most easily seen in liquids in narrow, open tubes. If the affinity between the liquid and the tube molecules is greater than between the liquid molecules themselves then the liquid will form a positive meniscus and it will climb the tube slightly (e.g. water in glass). If on the other hand the affinity is greatest between the liquid molecules then a negative meniscus will form and the liquid level will drop slightly (e.g. mercury in glass).

 

When a capillary tube is dipped in liquid,there occurs either rise or fall in liquid level in the capillary tube.This phenomenon is

known as capillary action.Two types of force bring about the capillary action.One is the intermolecular force of attraction between

the molecules liquid.This is known as COHESIVE force.Another is attraction force between the solid surface and liquid molecules .

This is known as A adhesive force.Water being polar molecule, the attraction between the glass and water molecule is quite strong.

This adhesive force is stronger than cohesive force in case of water surface interface.So water level rises up the glass capillary

tube with concave meniscus upward .The water level rises up until the adhesive force is balanced by the weight of water in the tube.

The tendency of water to spread over the glass surface is also due to the strong adhesive force between the glass and water molecules.

On the other hand water droplets in the waxed paper are spherical in shape because the adhesive force between polar water molecules and

non-polar wax is weaker than cohesive force.This cohesive force which gives rise to surface tension dominates over the adhesive force.

Therefore water droplets over the waxed paper are spherical in shape.  

If the capillary tube is dipped into mercury,a depression of the mercury level occurs with a convex meniscus upward.This happen because

the adhesive force between non-polar mercury and glass surface is relatively weak compared to the cohesive force in mercury.So mercury doesn't

spread over the glass surface,rather it tries to have minimum surface area and thus mercury meniscus in the glass tube is convex upward.

SURFACE TENSION

According to molecular concept of matter liquid is made of a large number of molecular.The molecules which are below the surface of liquid

are attracted from all directions those on the surface are attracted only towards the interior.Therefore, all the surface molecules experience resultant downward pull.

This force which exerts an inward pull on the molecules at the surface is called surface tension.Because of surface tension,the whole

surface behaves like a stretched elastic membrane under tension,which always tends to contract so as to keep the surface area minimum

The surface tension tends to reduce surface area of liquid as much as possible.This explains why the drop of the liquid assumes a spherical shape because a sphere has a minimum surface area for a given volume of the liquid

Energy is required to increase the surface area of liquid.The surface tension of a liquid is also the measure of the energy required to

increase the surface area by unit amount.Surface tension is defined as the force in dyneacting as aright angles to any line of a unit

length drawn on the surface of the liquid.It's units is dynes per cm in c.g.s units and newton per meter in SI units.

The greater the intermolecular force of attraction in a liquid, the greater will be its surface tension.The surface tension of water is

greater than of ethonal and ether.This mean that intermolecular force of attraction in water is stronger than in the case of ethonal

and ether.

Work Book, Spreadsheet, Worksheet and Cell

Work Book, Spreadsheet, Worksheet and Cell

A workbook is just like a large document with multiple topics related to each other. A workbook may contain multiple worksheets. Each workbook is given a name, which is generally known as file name. A worksheet is a part of workbook, which is combination of rows and columns (cells). This is the part of workbook where user is directly involved in writing his data, modifying or saving his data. A worksheet is also known as spreadsheet because it is a very large sheet (many times larger than manual sheets). Generally, a worksheet may have 256 columns and 65536 rows. Columns are vertical cut of a worksheet, which are given name with alphabets like A, B, C,…….., AA, AB, IV etc. A Row is vertical cut of a spreadsheet, which are given name with numbers like 1, 2, 3,………., 65536 etc. A cell is the smallest unit of a worksheet, in which we actually write data. Cross section of rows and columns is called cell. Each of the cells in a worksheet are identified with their cell address, which is composed up of writing the columns name first and then row numbers (e.g. A1,B5 etc).

   

data validation

In computer science, data validation is the process of ensuring that a program operates on clean, correct and useful data. It uses routines, often called "validation rules" or "check routines", that check for correctness, meaningfulness, and security of data that are input to the system. The rules may be implemented through the automated facilities of a data dictionary, or by the inclusion of explicit application program validation logic.

For business applications, data validation can be defined through declarative data integrity rules, or procedure-based business rules. Data that does not conform to these rules must negatively affect business process execution. Therefore, data validation should start with business process definition and set of business rules within this process. Rules can be collected through the requirements capture exercise.

The simplest data validation verifies that the characters provided come from a valid set. For example, telephone numbers should include the digits and possibly the characters +, -, (, and) (plus, minus, and parentheses). A more sophisticated data validation routine would check to see the user had entered a valid country code, i.e., that the number of digits entered matched the convention for the country or area specified.

Incorrect data validation can lead to data corruption or security vulnerability. Data validation checks that data are valid, sensible, reasonable, and secure before they are processed.

Data Filter

It is one of the facilities available in database package and is borrowed by spreadsheet package. We can see/filter only those rows/records, which match the given criteria. After the filter is on, each of the column/ fields will have a separate combo list. Whatever the condition we select from the List, the rows that match the given criteria will be displayed and others are hidden. It can be done by selecting the option ‘Data > Filter > >Auto Filter’ from menu.

 

CHARTS

 

A chart is a graphical representation of data, in which "the data is represented by symbols, such as bars in a bar chart, lines in a line chart, or slices in a chart”. A chart can represent tabular numeric data, functions or some kinds of qualitative structures.

Charts are often used to ease understanding of large quantities of data and the relationships between parts of the data. Charts can usually be read more quickly than the raw data that they are produced from. They are used in a wide variety of fields, and can be created by hand (often on graph paper) or by computer using a charting application. Certain types of charts are more useful for presenting a given data set than others. For example, data that presents percentages in different groups (such as "satisfied, not satisfied, unsure") are often displayed in a pie chart, but may be more easily understood when presented in a horizontal bar chart. On the other hand, data that represents numbers that change over a period of time (such as "annual revenue from 1990 to 2000") might be best shown as a line chart.

SPREAD SHEET (MS-Excel)

A spreadsheet is a computer application that simulates a paper, accounting worksheet. It displays multiple cells that together make up a grid consisting of rows and columns, each cell containing either alphanumeric text or numeric values. A spreadsheet cell may alternatively contain a formula that defines how the content of that cell is to be calculated from the contents of any other cell (or combination of cells) each time any cell is updated. Spreadsheets are frequently used for financial information because of their ability to re-calculate the entire sheet automatically after a change to a single cell is made.

VisiCalc is usually considered the first electronic spreadsheet (although this has been challenged), and it helped turn the Apple II computer into a success and greatly assisted in their widespread application. Lotus 1-2-3 was the leading spreadsheet when DOS was the dominant operating system. Excel now has the largest market share on the Windows and Macintosh platforms

Microsoft Excel (full name Microsoft Office Excel) is a spreadsheet application written and distributed by Microsoft for Microsoft Windows and Mac OS X. It features calculation, graphing tools, pivot tables and a macro programming language called VBA (Visual Basic for Applications). It has been a very widely applied spreadsheet for these platforms, especially since version 5 in 1993. Excel forms part of Microsoft Office. The current versions are Microsoft Office Excel 2007 for Windows and 2008 for Mac. In late 2009, Microsoft released the beta version of Microsoft Excel 2010.

Microsoft Excel has the basic features of all spreadsheets, using a grid of cells arranged in numbered rows and letter-named columns to organize data manipulations like arithmetic operations. It has a battery of supplied functions to answer statistical, engineering and financial needs. In addition, it can display data as line graphs, histograms and charts, and with a very limited three-dimensional graphical display. It allows sectioning of data to view its dependencies on various factors from different perspectives (using pivot tables and the scenario manager. And it has a programming aspect, Visual Basic for Applications, allowing the user to employ a wide variety of numerical methods, for example, for solving differential equations of mathematical physics, and then reporting the results back to the spreadsheet. Finally, it has a variety of interactive features allowing user interfaces that can completely hide the spreadsheet from the user, so the spreadsheet presents itself as a so-called application, or decision support system (DSS), via a custom-designed user interface, for example, a stock analyzer, or in general, as a design tool that asks the user questions and provides answers and reports. In a more elaborate realization, an Excel application automatically can poll external databases and measuring instruments using an update schedule, analyze the results, make a Word report or Power Point slide show, and e-mail the results on a regular basis to a list of participants.