2.6 GENOME PLASTICITY AND EVOLUTION OF ESCHERICHIA COLI
Like all life forms, new strains of E. coli evolve through the natural biological processes of mutation, gene duplication, and horizontal gene transfer; in particular, 18% of the genome of the laboratory strain MG1655 was horizontally acquired since the divergence from Salmonella. E. coli K-12 and E. coli B strains are the most frequently used varieties for laboratory purposes. Some strains develop traits that can be harmful to a host animal. These virulent strains typically cause a bout of diarrhea that is often self-limiting in healthy adults but is frequently lethal to children in the developing world. (Futadar et al., 2005). More virulent strains, such as O157:H7, cause serious illness or death in the elderly, the very young, or the immunocompromised.
The genera Escherichia and Salmonella diverged around 102 million years ago (credibility interval: 57–176 mya), which coincides with the divergence of their hosts: the former being found in mammals and the latter in birds and reptiles. (Wang et al., 2009). This was followed by a split of an Escherichia ancestor into five species (E. albertii, E. coli, E. fergusonii, E. hermannii, and E. vulneris). The last E. coli ancestor split between 20 and 30 million years ago.
The long-term evolution experiments using E. coli, begun by Richard Lenski in 1988, have allowed direct observation of genome evolution over more than 65,000 generations in the laboratory. For instance, E. coli typically do not have the ability to grow aerobically with citrate as a carbon source, which is used as a diagnostic criterion with which to differentiate E. coli from other, closely, related bacteria such as Salmonella. In this experiment, one population of E. coli unexpectedly evolved the ability to aerobically metabolize citrate, a major evolutionary shift with some hallmarks of microbial speciation.
2.7 INCUBATION PERIOD
The time between ingesting the STEC bacteria and feeling sick is called the “incubation period”. The incubation period is usually 3–4 days after the exposure, but may be as short as 1 day or as long as 10 days. The symptoms often begin slowly with mild belly pain or non-bloody diarrhea that worsens over several days. HUS, if it occurs, develops an average of 7 days after the first symptoms, when the diarrhea is improving.

2.7.1 DISCOVERY OF ANTIBIOTICS
• History of antibiotics – 1
19th century:Louis Pasteur & Robert Koch
• History of antibiotics – 2
Plant extracts
– Quinine (against malaria)
– Ipecacuanha root (emetic, e.g. in dysentery)
Toxic metals
– Mercury (against syphilis)
– Arsenic (Atoxyl, against Trypanosoma)
• Dyes
– Trypan Blue (Ehrlich)
– Prontosil (azo-dye, Domagk, 1936)
• History of antibiotics – 3
Paul Ehrlich
• started science of chemotherapy
• Systematic chemical modifications
(“Magic Bullet”) no. 606 compound = Salvarsan (1910)
• Selective toxicity.
• Developed the Chemotherapeutic Index
• History of antibiotics – 4
Penicillin- the first antibiotic – 1928• Alexander Fleming observed the
killing of staphylococci by a fungus (Penicillium notatum)
• observed by others – never exploited
• Florey & Chain purified it by freeze-drying (1940) – Nobel prize 1945
• First used in a patient: 1942
• World War II: penicillin saved 12-15% of lives
• History of antibiotics – 5
Selman Waksman – Streptomycin (1943), was the first scientist who discovered antibiotic active against all Gram-negatives for examples; Mycobacterium tuberculosis
– Most severe infections were caused by Gram-negatives and Mycobacterium
tuberculosis, extracted from Streptomyces – extracted from Streptomyces
– 20 other antibiotics include. neomycin, actinomycin
2.8 CHARACTERISTICS OF ANTIBIOTICS
According to the Oxford Dictionary, the term Antibiotics encompasses medicines (such as penicillin or its derivatives) that inhibit the growth of or destroys microorganisms. Antibiotics are naturally occurring substances that exhibit inhibitory properties towards microbial growth at high concentrations. (Zaffiri, et al., 2012).
-Antibiotics are selective in their effect on different microorganisms, being specific in their action not only against genera and species but even against strains and individual cells. Some of these agents act mainly on gram-positive bacteria, while others inhibit only gram-negative ones.
-Some antibiotics are produced by some organism, from different strains of penicillin.
-Bacteria are sensitive to the antibiotic which enable them to developed resistance after contact, for several periods.

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2.9 ROLE OF ANTIBIOTICS
Based on the clinical use of antibiotics, it may appear that these compounds play a similar role as microbial weapons in nature, yet this seems unlikely due to the fact that the concentrations used in the clinical setting are significantly higher than that produced in nature (Fajardo et al., 2008). Due to experimental evidence, it makes more sense to see antibiotics as small, secreted molecules involved in cell-to-cell communication within microbial communities.
(Martinez, 2008). Diverse Studies have been conducted in which different antibiotics and antibiotic-like structures were administered to different bacterial species at levels below the compounds minimum inhibitory concentrations (MIC). (Fajardo et al., 2008). that was

2. HOW DERIVATIVES CAN BE USED FOR HEDGING RISKS.

Hedging with Options Contracts
Option contract is an agreement that give a holder the right to purchase or sell currency for an agreed price and at a certain amount of currency at a specified time in the future. However, the option holder is not obligated to exercise the contract. Therefore, the holder has to pay premium to the broker, a firm or individual who carry out the orders to buy or sell currency option contracts on the behalf of holder (Pike & Neale, 2009)
Classification of option contract according to (Bodie & Kane & Marcus, 1999)
Call option, this gives the holder the right to buy a certain quantity of currency at the exercise/strike price in a specified period of time.

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Put option, this gives the holder the right to sell a certain quantity of currency at the exercise/strike price in a specified period of time.
Two types of option contract basing on the terms on exercise in the contract according to (Bodie & Kane & Marcus, 1999)
European style options, this allow the holders to exercise the option only on the expiration date.
American style options, this allow the holders to exercise the contract at any time up to the expiration date.

Illustration1.
The Group 6 Company October 30 call option is quoted at TZS 500/-, the Group 6 Company October 30 put option is quoted at TZS 1,500/-, while the Group 6 Company spot price is quoted at TZS 28,000/-. The call option is said to be out of the money since its immediate exercise (if possible) has no value. Conversely, the put option is in the money. Suppose the Group 6 Company spot price rises to TZS 31,000/- on October 16, which is the option maturity date. Then, the call holder is better of exercising his right and making a profit of TZS 1,000/-. The call expires in the money, while the put expires out of the money.

According to (Nguyen, 2012), there are two parties engaged in the option contract which are option holder and option writer.

Figure1. Participants in option contract
Option holder/option buyer/option taker is the party which grants another one the option but not an obligation to do or not to do something. In addition, this party has a right to choose to purchase or sell currency at specified price within a certain period of time.

Option writer/option seller/ option granter is the party who is obliged to fulfill that choice in accordance with the terms of contractual option.
Premium is the non-refundable cost for which holder is required to pay to gain the possession of option at the outset regardless of whether option will be exercised or not (Wilmott, 2000).

Hedging with Forward Contracts
Bodie & Kane & Marcus (1999) defined forward contract as a non-standardized contract entered by two parties or more with the intention of exchanging one currency for another at an agreed rate and at a certain quantity on a specified future date. According to (Wilmott, 2000, p 26) in forward contract, strike price is the rate on which one currency is based to be converted to another currency as the contract is exercised. The certain date at which the contract is due to be exercised is called expiration date and also the action to perform the obligation to deliver currency under the terms of contract is called exercise.
Illustration.2
Assume that a US construction company, Group 6 ltd just won a contract to build a stretch of road in Tanzania. The contract is signed for TZS 10,000,000 and would be paid for after the completion of the work. This amount is consistent with Group 6 ltd minimum revenue of TZS 1,000,000 at the exchange rate of $0.10 per TZS. However, since the exchange rate could fluctuate and end with a possible depreciation of TZS, Group 6 ltd enters into a forward agreement with CRDB to fix the exchange rate.

Hedging with Futures Contracts
Future contract is a standardized contractual agreement in which two parties promise to exchange one currency for another at a pre-determined rate and at a certain quantity on a specified future date (Arnold, 2010).

Illustration3.

As for hedging with futures, if the risk is an appreciation of value one needs to buy futures and if the risk is depreciation then one needs to sell futures. Let’s assume accordingly that Group 6 ltd sold Rupee futures at the rate RM0.10 per Rupee. Hence the size of the contract is RM1, 000,000. Now say that Rupee depreciates to RM0.07 per Rupee – the very thing Group 6 ltd was afraid of. Group 6 ltd would then close the futures contract by buying back the contract at this new rate.
Hedgers are parties at risk with an underlying asset and they decide to take out (buy or sell) derivative instruments to offset their risks. There are 2 hedge positions which are;
Long hedge
This is maintained by the party who commits to purchasing the currency in the future. This is because this party is currently not holding any contractual currency and expects to possess it sometime in the future. Since the party is seen to be short on the cash position therefore, the party wishes to lock in purchase prices and use a long hedge, which reduces the risk of a short position (Jones, 2002).

Short hedge
This is maintained by the party who commit to selling the currency in the future. This is because the party is currently holding the contractual currency. Since the party is seen to be long on the cash position so the party needs to protect themselves against a decrease in prices. Hence, a short hedge mitigate the risk taken in a long position (Hull, 2011)
Figure2. Hedge positions in future or forward contracts (Nguyan, 2012).Hedging with Swaps
Currency swap is the agreement between two parties to swap both the periodic interest payments and principal denominated in one currency into another currency at the agreed upon rate of exchange for the specific period of time. However, on the maturity date, each party is required to return the other the swapped principal sum (Watson ; Head, 2010).

Illustration4.
A company agrees to pay its bank semi- annual interest over 20 years, based on a fixed nominal interest rate of 5.5% (per year), and to receive interest payments based on a floating interest rate, say, the 6 month LIBOR rate. Both interest payments assume a principal amount of TZS 1 million. No payment is exchanged up front. Several swaps are traded over the counter, namely, interest rate swaps, currency swaps, equity swaps, and the more recently introduced and controversial credit default swaps. There are several combinations of derivative contracts, such as options on swaps or swaptions, options on futures contracts, and options embedded in bonds, among others.

3. ARGUMENT FOR AND AGAINST THESE OF DERIVATIVES IN HEDGING RISK.
Arguments for (Benefits):
Derivatives help to gain the certainty concerning a future outcome
Under the strong fluctuating currency market, neither of parties is able to predict accurately what actual exchange rate in the future will be. Therefore derivatives for example forward contract assists in the protection of unfavorable exchange rate movement which causes fluctuation that can lead to loss of large amounts of money in firms from the decrease in over sale price or from the sudden rise in imported material cost (Stephens, 2003).

Derivatives allow firms to set accurate budget and stick to the financial plan
This is because the exact values of future transaction are calculated. This also means that derivatives enable firms to focus on their business activities in order to reap the huge profit instead of wasting time, capital and resources on keeping a constant track of fluctuation of exchange rate (Stephens, 2003).
Arguments against:
Unable to withdraw from the contract
Once the two parties enter the derivative contracts for example forward contract, they are legally obliged to carry it out up to the maturity date even if the business circumstance changes. However, (Stephens, 2003) argue that if one party seeks to withdraw from the contract will certainly suffer from the relatively high cost of cancellation. This means that when it comes to the situation in which the exchange rate in the market moves against one party’s interest, the firm is not allowed to withdraw from its contracted position in order to grab profit from such a profitable movement (Watson & Head, 2010).

High degree of credit risk arising from two sources
Firstly, there is no initial cost or deposit requirement when undertaking the contracts. Secondly, the gains and losses between two parties are figured out at the time the contract becomes mature and related currency are delivered at the pre-determined price. Consequently, it is quite an inducement to the party going to suffer from the loss, or to the party which no longer need to trade the contractual currency, to default on the forward contract (Hutchninson & Thornes, 1995).

REFERENCES
Pike, R. & Neale , B. (2009). “Corporate Finance and Investment : Decisions and Strategies”.6th ed. FT Prentice Hall Financial Times.

Hutchinson, R. & Thornes , S. ( 1995 ). “Corporate Finance : Principles of investment , financing and valuation ” . Robert Stanley Publishers Ltd .Bodie & Kane & Marcus. ( 1999) . “Investments”.4th ed. Irwin / McGraw Hill
Arnold , G . (2010) .”The financial times guide to investing” . 2nd ed. Financial times Prentice Hall Pearson.

Stephens , J. (2003). “Managing currency risk : Using Financial derivatives”. The institute of international auditors UK and Ireland. University Edition .Hull, J. (2011) . “Options, Futures, And other derivatives” . 8th ed . Pearson.

Watson, D. & Head , A. (2010). “Corporate finance : Principle & Practice”. 5th ed. Prentice Hall Financial Times.Wilmott , P. ( 2000 ). “Derivatives :The theory and Practice of Financial Engineering”. University Edition
Jones , C. (2002). “Investment Analysis and Management”.8th ed. North Caroline StateUniversity.Arnold , G . (2010) .”The financial times guide to investing” . 2nd ed. Financial timesPrentice Hall Pearson.

2.6 GENOME PLASTICITY AND EVOLUTION OF ESCHERICHIA COLI
Like all life forms, new strains of E. coli evolve through the natural biological processes of mutation, gene duplication, and horizontal gene transfer; in particular, 18% of the genome of the laboratory strain MG1655 was horizontally acquired since the divergence from Salmonella. E. coli K-12 and E. coli B strains are the most frequently used varieties for laboratory purposes. Some strains develop traits that can be harmful to a host animal. These virulent strains typically cause a bout of diarrhea that is often self-limiting in healthy adults but is frequently lethal to children in the developing world. (Futadar et al., 2005). More virulent strains, such as O157:H7, cause serious illness or death in the elderly, the very young, or the immunocompromised.
The genera Escherichia and Salmonella diverged around 102 million years ago (credibility interval: 57–176 mya), which coincides with the divergence of their hosts: the former being found in mammals and the latter in birds and reptiles. (Wang et al., 2009). This was followed by a split of an Escherichia ancestor into five species (E. albertii, E. coli, E. fergusonii, E. hermannii, and E. vulneris). The last E. coli ancestor split between 20 and 30 million years ago.
The long-term evolution experiments using E. coli, begun by Richard Lenski in 1988, have allowed direct observation of genome evolution over more than 65,000 generations in the laboratory. For instance, E. coli typically do not have the ability to grow aerobically with citrate as a carbon source, which is used as a diagnostic criterion with which to differentiate E. coli from other, closely, related bacteria such as Salmonella. In this experiment, one population of E. coli unexpectedly evolved the ability to aerobically metabolize citrate, a major evolutionary shift with some hallmarks of microbial speciation.
2.7 INCUBATION PERIOD
The time between ingesting the STEC bacteria and feeling sick is called the “incubation period”. The incubation period is usually 3–4 days after the exposure, but may be as short as 1 day or as long as 10 days. The symptoms often begin slowly with mild belly pain or non-bloody diarrhea that worsens over several days. HUS, if it occurs, develops an average of 7 days after the first symptoms, when the diarrhea is improving.

2.7.1 DISCOVERY OF ANTIBIOTICS
• History of antibiotics – 1
19th century:Louis Pasteur & Robert Koch
• History of antibiotics – 2
Plant extracts
– Quinine (against malaria)
– Ipecacuanha root (emetic, e.g. in dysentery)
Toxic metals
– Mercury (against syphilis)
– Arsenic (Atoxyl, against Trypanosoma)
• Dyes
– Trypan Blue (Ehrlich)
– Prontosil (azo-dye, Domagk, 1936)
• History of antibiotics – 3
Paul Ehrlich
• started science of chemotherapy
• Systematic chemical modifications
(“Magic Bullet”) no. 606 compound = Salvarsan (1910)
• Selective toxicity.
• Developed the Chemotherapeutic Index
• History of antibiotics – 4
Penicillin- the first antibiotic – 1928• Alexander Fleming observed the
killing of staphylococci by a fungus (Penicillium notatum)
• observed by others – never exploited
• Florey & Chain purified it by freeze-drying (1940) – Nobel prize 1945
• First used in a patient: 1942
• World War II: penicillin saved 12-15% of lives
• History of antibiotics – 5
Selman Waksman – Streptomycin (1943), was the first scientist who discovered antibiotic active against all Gram-negatives for examples; Mycobacterium tuberculosis
– Most severe infections were caused by Gram-negatives and Mycobacterium
tuberculosis, extracted from Streptomyces – extracted from Streptomyces
– 20 other antibiotics include. neomycin, actinomycin
2.8 CHARACTERISTICS OF ANTIBIOTICS
According to the Oxford Dictionary, the term Antibiotics encompasses medicines (such as penicillin or its derivatives) that inhibit the growth of or destroys microorganisms. Antibiotics are naturally occurring substances that exhibit inhibitory properties towards microbial growth at high concentrations. (Zaffiri, et al., 2012).
-Antibiotics are selective in their effect on different microorganisms, being specific in their action not only against genera and species but even against strains and individual cells. Some of these agents act mainly on gram-positive bacteria, while others inhibit only gram-negative ones.
-Some antibiotics are produced by some organism, from different strains of penicillin.
-Bacteria are sensitive to the antibiotic which enable them to developed resistance after contact, for several periods.

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2.9 ROLE OF ANTIBIOTICS
Based on the clinical use of antibiotics, it may appear that these compounds play a similar role as microbial weapons in nature, yet this seems unlikely due to the fact that the concentrations used in the clinical setting are significantly higher than that produced in nature (Fajardo et al., 2008). Due to experimental evidence, it makes more sense to see antibiotics as small, secreted molecules involved in cell-to-cell communication within microbial communities.
(Martinez, 2008). Diverse Studies have been conducted in which different antibiotics and antibiotic-like structures were administered to different bacterial species at levels below the compounds minimum inhibitory concentrations (MIC). (Fajardo et al., 2008). that was

2.1 Basic concept for thermoluminescent
Basically, thermoluminescence is where the absorbed radiation can be released from the crystalline materials in form of luminescence when being heated at its maximum temperature. The processes of the thermoluminescence have two stage. Alawiah (2015) used one trap and one center (OTOR) as a model. To describe the TL properties, the theory of the energy band is used (Alawiah, 2015 and Piters, 1993).

2.1.1 Mechanism of thermoluminescence
The first stages in thermoluminescence process are by absorption of energy from ionizing radiation which causes the change of the system from equilibrium to a metastable state. This stage is known as energy storage. To stabilize the absorbed energy, electronic excitation, and the displacement damage is controlled. The defect creation can happen if the electronic excitation and the displacement damage is not stabilized correctly. Some of the localized electronic states are occupied by a non-equilibrium concentration of electrons cause radiation-induced defects and less amount of electrons being trapped. The electron-hole pair production and excitation creation work as energy storage for electronic excitation (Shodhganga.inflibnet.ac.in. 2018).

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Mobile holes and electrons in the crystal structure are will be formed the electron-hole pair production in the material after being irradiated. Preexisting impurities or radiation-induced defect have defected which causes the presence of a mid-gap state and form between the two energy bands. There are two types of energy bands; valence band (placed at the outermost energy level and consists of electron-hole pairs) and conduction band (the higher energy level where the electron is free to move and produce electric current).

By referring to Attix (2004), there are two types of crystal-lattice imperfections such as electron traps and hole traps that might be located the luminescence centers where when the electron and hole are permitted to recombine causes the light to be emitted. This traps might be located either in the conduction band or in the valence band.

Figure 2.1 Energy-level diagram of the energy storage stage
Note. From Shodhganga.inflibnet.ac.in. 2018
When radiation is applied, the electron passing through to conduction band from valence band and the hole charged area in the valance band became positively charged. The electron excited into the conduction band and recombine with either electron trap and holes trap. Hole traps and electron traps are known as a luminescence center.

Figure 2.2 Energy-level diagram of the energy release stage
Note. From Shodhganga.inflibnet.ac.in. 2018

As energy is released in the form of light when being heated known as relaxation stage where relaxation of the system back to the equilibrium. When the temperature reaches its maximum limits, the energy released the traps in conduction band results in the release of the storage energy by electron de-excitation event and cause the change in material from the metastable state to ground state. The electron is then free to be trapped again or recombine with the hole in the hole trap that emits energy in the form of light. The hole traps are known as recombination station for this mechanism.

2.1.2 Randall-Wilkins theory
The trapped charge carries escaped can be determine using first-order kinetic energy at a temperature (T) as described by Randall and Wilkins 1945 (Attix, 2004). The equation used is:
p=1/?=???exp?^(-E/kT)
Where p is the probability of escape per unit time (-s)
? is the mean life time in the trap
? is the frequency factor
E is the energy depth of the trap (eV)
k is the Boltzman’s constant (1.381 × 10-23 J K-1 = 8.62 × 10-5 eV K-1)
The values of ?, E, and k are assumed as constant. With increasing in T causes the values of p to increase and ? to decrease. When T has scanned upward linearity against time, the rate of escape of trapped electron increase with starting temperature at room temperature. The maximum temperature, Tm is followed by decreases in the electron trapped supply as the trapped electron is gradually exhausted.