Cellular Microbiology Essay Example | Topics and Well Written Essays - 2000 words

Cellular Microbiology - Essay Example (Institute of Materials, Great Britain, P. 223) The importance is far reaching, from environmental O2 /CO2 balance to the synthesis of artificial herbicides that act on unwanted herbs by blocking some important steps in this energy producing process. The chlorophyll pigment alone has lead to new avenues for thoughts and research on the importance of photosynthetic processes and has paved the way for the synthesis of certain medicinal drugs exploiting its photoprotective mechanisms for preventing light induced damage of cells. The chlorophyll research has added to the significance of this novel energy yielding life process and has led to the foundation of drug therapy for treatment of tumors, carcinoma and related maladies. In fact the earliest forms of photosynthetic plants principally inhabited the water bodies, especially in the warm mineral rich pools, mainly due to the intense effect of ultraviolet radiation on the land due to the absence of the ozone layer. Instead of oxidizing, with a highly reducing nature of environment, principally due to the sparse oxygen count, the warm pools full of evolving life forms probably utilized the massive energy resource to convert the simple inorganic compounds to complex organic biomolecules, like, purines, pyrimidines, nucleosides, nucleotides, etc, paving the way for the synthesis of nucleic acids and complex proteins and enzymes. (Pearson, P. 10) This definitely potentiated the production of biomolecules required oxygen production. As the oxygen level in the atmosphere increased slowly with the passage of time, plants reached out and slowly colonized the lands progressively transforming their semi-aquatic habitats to terrestrial by nature. With the evolution of the earliest microbes that resembled cyanobacteria, algae and lichens till the further differentiated poikilohydric bryophytes evolved. About 25 million years ago, these non vascular bryophytes were soon followed with vascular homioihydric plants capable of maintaining their internal water content at an optimum level irrespective of the external environmental conditions. However before the origin of these photosynthesizing life forms the challengingly low levels of atmospheric oxygen as hypothesized by the geologists, required an explanation of unknown factors that increased the atmospheric oxygen count at a considerable extent. This unknown process of oxygen accumulation in the atmosphere through an unexplained time gap of hundred million years can be associated with a number of presumable theories each of which has its own investigational platform. "The red line shows the inferred level of atmospheric oxygen bounded by the constraints imposed by the proxy record of atmospheric oxygen variation over Earth's history. The signature of mass-independent sulphur-isotope behaviour sets an upper limit for oxygen levels before 2.45 billion years ago and a lower limit after that time. The record of oxidative weathering after 2.45 billion years ago sets a lower limit for oxygen levels at 1% of PAL, whereas an upper limit of 40% of PAL is inferred from the evidence for anoxic oceans during the Proterozoic. The tighter bounds on atmospheric oxygen from 420 million years ago to the present is set by the fairly continuous

SSL Security Essay Example | Topics and Well Written Essays - 750 words

SSL Security - Essay Example SSL implementations provide various secret and public key encryption algorithms. The secret algorithm keys employ key lengths spanning from 40 to 168 bits. Most SSL software is limited to 521 bit RSA keys and 40 bit secret keys given export restrictions (Bossley). Brute force searches are a technique that exhaustively tries out possible keys until an appropriate one is found. In a bid to identify an appropriate key, it is required that one be in possession of a plaintext and the corresponding ciphertext (Eugene, 2). Advancements in technology resulting in enhanced computing performance have increasingly made practical exhaustive key searches against keys that are of fixed length. The dictionary attack is the most effective type of known plaintext attacks especially when a reduced number of crypto keys are used. Attackers thereby develop a dictionary comprising all possible encryptions of known plaintext messages such as the Get command. On receiving the encrypted message, the dictionary looks it up. An attack occurs when the ciphertext matches a particular entry in the dictionary that was previously encrypted using an identical secret key (Giacomo 1). SSL prevents dictionary attacks by using the 128 bit keys wherein 40 bits are kept secret while the rest are derived from the data revealed in hello messages. The combination of both the 40 bit secret key and the 88 bit known key results in an encryption that employs all 128 bits. This renders dictionary attacks impossible given that they also should have differentiated entries in order to realize all 128 bit keys. SSL prevents replay attacks during handshaking protocols through the use of a 128bit nonce which is unique to a given connection. The nonce is unpredictable in advance given that it is based on events that are also unpredictable (Bossley). The attacker gathers messages earlier transmitted and replays them in a bid to repeat interesting transactions such as the transfer of money. In this