Review Essay Example | Topics and Well Written Essays - 1000 words - 4

Review - Essay Example He goes on to explain that there are possibilities for a wrongful diagnosis that then poses the question what do the parents do with the information? Is it ethical for a parent to make the decision for their child’s life when a mutation in a gene does not necessarily prove they will contract the disease? David Devore was a participant in the Woodrow Wilson Biology Institute where he conducted much research on the topic in this article. He has extensive knowledge in genetics and has provided a lot of detailed information from many other sources. Devore believes genetic screening for diseases such as Lesch-Nyhan syndrome which causes mental retardation after the first few days of life is necessary and beneficial to both the parents and the offspring but that screening for diseases like alcoholism or Alzheimer’s is not beneficial and may be detrimental to the child’s life. Even though a child may possess the gene responsible for the disease does not mean they will contract it. Therefore Devore believes genetic counseling should also be available after the results are received. I chose this source because it not only describes the techniques of genetic screening but also the positives and negatives of screening for different diseases and the consequences of both choices. I t provides rich information on my argument as to whether it is ethical to conduct these tests and the consequences of the parents’ decisions based on that information. I found this source on the internet in another institution publication. The only thing missing are first-hand accounts from individuals. The article â€Å"Genetic Screening, the Social Impact of Genetic Knowledge† by Boris Sagredo describes the process of genetic screening and the use of assays to compare individuals in a population to determine a difference in the genes. Although genetic screening can predict a possibly contraction of a disorder based on the

Steam Distillation of Eugenol Essay Example for Free

Steam Distillation of Eugenol Essay Introduction: This experiment involves an extraction of a natural product using the techniques of steam distillation. The principle component of oil of cloves is an aromatic compound, which is identified by thin layer chromatography (TLC). Eugenol is widely used in dentistry, due to its analgesic, antiseptic balsamic qualities. It is ideal for curative for pulp hyperemia (the soft, sensitive substance underneath the enamel and dentine of a tooth) and pulp its. In dentistry eugenol is also used to cover cavities, fill canals, etc. It also keeps food fresh and kills off bacteria and viruses. Eugenol helps keep meat fresh and prevents stomach upset, diarrhea, and wound infections. In addition, it might play a part in relieving indigestion, controlling diarrhea, and healing cuts and bites. Eugenol is the main active ingredient in cloves. Procedure: 1. In a 250 mL round bottom flask, place 10.0g of ground cloves and 80 mL of water. Set up for a simple distillation 2. Heat to boiling and collect the distillate until you no longer see droplets of organic liquid coming out of the condenser (about 40 minutes). 3. Place the distillate in a separatory funnel and extract with three 10 mL portions of Dichloromethane 4. Combine the dichloromethane extracts and dry over Sodium Sulfate. 5. Examine the purity of the extract using thin-layer chromatography (TLC). Spot a small sample of the extract using a capillary spotter about 1 cm from the end of TLC plate. 6. Visualize using a UV light and mark the visualized spots with a pencil. 7. Record the number of spots and the Rf values from the spot(s). 8. While the plate is developing set up a clean and dry distillation set up and distil off most of the dichloromethane solvent. 9. The remaining solution of Eugenol in Dichloromethane can be removed using a disposable pipette and placed into a clean pre-weighted vial. 10. The vial can be heated on a steam bath under the hood to remove the small amount of dichloromethane. 11. The pure Eugenol should be weighted to determine the percent oil recovered based on the mass of cloves originally used. Results: Density of Eugenol: 1.34 g/mL BP of Eugenol: 40Â °C Initial mass of Eugenol: 18.545 g Mass of vial: 18.0063 g Mass of Eugenol Oil: 18.434 g % Recovery = (18.545 g 18.434 g)/18.434 x 100 = 0.602% Thin layer chromatography: Rf=(Distance substance moved/Distance solvent moved) Rf=(4.2/5.1) Rf=(.824) Conclusion: The experiment was successful in that we did isolate eugenol as proven by thin layer chromatography. Our Rf value was somewhat high. This is probably because the beaker with the chloroform was not 100 % closed during the time we did the thin layer chromatography. Our watch glass was not 100% efficient. Also when we were heating the liquid in the condenser, heating the liquid at a rate too high could cause excess materials to come out in the final product. Other than that, human error is a concern. This can be minimized by careful observation, and proper procedure. Still, our percent error was under 1 percent, which is very favorable.

Sensory Systems in Animals

Sensory Systems in Animals All animals have some kind of nervous system that can receive and interpret information about its internal and external environment. Sensory organs provide a means for communication from the external environment to the internal. Sensory receptors contain receptor cells that are specialised to respond to specialised stimuli. These sensory organs may be found all over the body or in localised areas. Afferent neurons carry the sensory information from the periphery toward and into the central nervous system while the efferent neurons carry information away from the central nervous system. Sensations arising when signals initiated in sensory receptors are transmitted in certain parts of the brain, producing signals in certain parts of the brain. (Hickman, Roberts, Keen, 2009) Stimulus types possess features that can be distinguished from one another. In the body of an animal the sensory receptor cells are usually modified. For example, certain receptors detect pressure, heat, chemicals, light and even pain. The stimulus for light detection and chemical detection is different and in addition, the same type of stimulus may possess different features. This can be seen, in for example the detection of blue and red light, both being perceived as a stimulus of light. In the first part of this practical the sensory structures of a number of invertebrate organisms were studied and compared to each other. Mainly chemoreception, photoreception and mechanoreception were studied. Chemicals in the animals surrounding is detected by a number of chemoreceptors. Chemoreceptors may be divided into two main categories; olfactory (smell), which respond to airborne molecules and gustatory (taste), responding to dissolved molecules. Mechanoreceptors are made up of undifferentiated nerve endings found in connective tissue on the periphery of the animal such as the skin. More complex accessory structures have accessory structures that transfer mechanical energy to the receptive membrane. These mechanoreceptors are also able to filter the mechanical energy and they may also include the muscle stretch receptors Photoreception consists of transducing photons of light into electrical signals that can be interpreted by the nervous system and photoreceptive organs such as the eyes. These sensory structures in different animals have taken many different shapes and sizes that have been adapted to the particular environment best for them. Although quite different all the sensory structure of particular receptor has the same function of collecting information from the environment and responding in the best way possible to enhance its survival. Apparatus Light Microscope cardboard Stereomicroscope 1g-5g, 10 g, 20 g, 50, 100 g weights Pencil x3 500 mL water bath Pointed forceps heater/Bunsen to heat water Stop watch thermometer X3 5 c coins Method Refer to attached sheet Precautions The plastomounts were placed under a stereomicroscope for better viewing of small body features The same pair of forceps was used to apply the stimulus since different instruments could result in different outcomes. As much as possible the coin was placed in the sample place for all subjects since different area may have a different amount of receptors. The temperature in the water baths was measured before the experiment was conducted. This was done so that the initial temperature of the water for all the subjects would be the same. Thus the results would be more comparable. Sources of Error Due to the clothing worn the experiment of tactile response using the forceps had to be carried out over the clothing. This thus formed an extra layer that could decrease the response of the nerve. Not all the sensory structures of the organisms may have been identified. The experiments on each subject were only carried out once. More accurate results would have been obtained if carried out at least 3 times Results Part A Refer to attached diagrams Thermoreception For all 3 subjects the cold water was almost painful, while the water at 45 degrees was soothing. On placing the hand in the water at room temperature the right hand felt the water warm while the left hand (previously in the warm water) felt the water cold. Discussion Part A: Invertebrates These sensory structures in different animals have taken many different shapes and sizes that have been adapted to the particular environment best for them. These mainly have evolved from simple to more complex sensory organs that enhance the ability of the animal in collecting information from the environment and responding in the best way possible to enhance its survival. The Cnidarian Hydra, has relatively simple sensory cells scattered all over the body among the other epidermal cells, especially the mouth and tentacles. It is of utmost importance for sensory structures to be located all over the body due to the fact that the animal is radially symmetrical and can detect stimuli from all direction, including the detection of predators. The free end of every sensory cell bears a flagellum, which is the sensory receptor for chemical and tactile stimuli. The other end branches into fine processes, which synapse with nerve cells. On the surface of the animal is a modified cilia called a Cnidocil, that when simulated by any mechanical stimulation releases a nematocyst that is toxic to the predator. (Barnes Cawlow, 2002) These sense organs then lead into a diffuse nerve network, forming two interconnected nerve nets. It is of utmost importance for sensory structures to be located all over the body due to the fact that the animal is radially symmetrical and can detect stimuli from all direction, including the detection of predators. (Hickman, Roberts, Keen, 2009) From the radially symmetrical Cnidarian one can move on to the bilaterally symmetrical Platyhelminthes that is represented here by the Planaria. Here the nervous system is organised into two longitudinal nerve chords that end in the anterior of the animal. This forms an anterior head and cephalisation is introduced. (Hickman, Roberts, Keen, 2009) The Planaria, unlike the Hydra are seen to have an eye spot and auricles. The auricles are lobe like and are found on the sides of the head. The auricles act as a means of chemoreception while the eye spot serves as photoreceptor detecting light. Like the Hydra, it may also contain a statocyst for equilibrium and rheoreceptors for sensing water currents. Cephalisation allowed the animal to develop a bilaterally symmetrical shape. The animal moved forward and can detect changes in the environment with the part of the body with the most sensory organs, its anterior region. (Leineschh, 2007) The Pulmonate gastropod, belonging to the class Gastropoda is seen to further develop its sensory in the anterior of the body. In the anterior of the body the animal is seen to have paired eyes that function as photoreceptors, even though they are not capable of forming an image. Also the labial  and  cephalic tentacles  are mechanoreceptors, sensitive to tactile stimuli, and are probably also chemoreceptive.  Ã‚  Ã‚  (Hickman, Roberts, Keen, 2009) The general body surface is also sensitive to chemical and mechanical stimuli.  Ã‚  The gastropod also has a structure that acts as both a mechanical and chemoreceptor. This is seen to be the osphradium  which is located in the inhalant respiratory water current where it monitors water on the way to the gill. A common structure with the previously studied animals is the statocyst which functions as a detector of gravity. (Hickman, Roberts, Keen, 2009) The next three species studied all belong to the phylum Arthropoda, but are found in different classes. The first to be studied was the Tarantula found in the class Arachnida (order Aranea). This animal has hair like receptors called sensory setae that function as mechanoreceptors all over the body of the animal. Also, in addition they have small, extremely sensitive tactile hairs called trichobothria that are sensitive to even airborne vibrations, including sound frequencies. Chemoreception is associated with fine hairs surrounding the mouth, on the pedipalps. (Hickman, Roberts, Keen, 2009) The tarantula also has 8 simple eyes that are made up of a lens, optical rods, and a retina. Even though most only can detect movement like the previously studied animals, some are able to form images. Since the spider is more accustomed to capturing prey within webs, vision is relatively unimportant and thus in most remain simple. (Underwood, 2009) Another member of the phylum Arthropoda is the scorpion, classified in the class Scorpionida. Although they are equipped with venom for defence the scorpion is still seen to be the prey of many other animals, thus they require specialised sensory structures for detection of danger. This animal is seen to possess a unique sensory structure know as a pectine. This is used primarily in detecting vibrations which are used for capturing prey. (Gaoge Smith , 2000) This is seen to be the primary chemosensory organs of scorpions. The pectines are found in the ventral medial part of body and are seen to be paired appendages that brush the substrate as the scorpion walks. Comb-like organ consists of a supportive spine and an array of teeth. Each tooth supports hundreds of setaform sensilla called pegs. The neuronal cell layer within the teeth is seen to be further divided into inner and outer sub-larninae, comprised of chemosensory and mechanosensory neurons. (Melville, 2000) Similar to the arachnids described previously, the scorpion has sensory hairs called setae that function as tactile and chemosensory hairs. These sensory hairs are also found on the pedipalps of the animal to sense air-borne vibrations. Also, thicker setae are found all over the body to detect direct touch. In contrast to the spiders the scorpions possess six pairs of eyes as part of their photoreceptor structure. The last arthropod group to be described is the centipede, classified into the sub-phylum Myiapoda and order Centipedes. These animals are seen to possess one pair of antennae instead of the usual two paid found in other arthropods. The antennae are sensory appendages found in the head of the animal that are sensitive to airborne chemicals and also possibly humidity. Similar to the planaria, Centipedes also bears a pair of simple eyes made up of ocelli. (Barnes Cawlow, 2002) Part B: Sensory function in Mammals Mechanoreception Somatosensory system has a large number of receptrors which vary in location and type. Receptors are located in the superfial skin, dermal, epidermal and depper in dermis, and in subcutaneous tissue. Meissners corpusles are located in the dermal papillae, Merkels receptors in the dermal papillae, and bare nerve endings. Subcuateous receptors, beneath both the previously mentiones layers, possess pacinian and Rufflin corpusles. Pacinian may be both cutaneous and subcutaneous. (Wang , 2007) The Pacinian corpusles are present in the skin, muscles, mesentery, tendons, and joints of mammals that are rapidly adapting. Each Pacinian corpuscle contains a region of receptor membrane that is sensitive to mechanical stimuli and that is surrounded by concentric lamellae of connective tissue structures (Anonymous, 2007) Pressure on the corpuscle transmits mechanically through the layers to the sensitive membrane of the receptor neuron. The receptor membrane normally responds with a brief, transient depolarization at both the onset and the offset of the deformation. The mechanical properties of the intact corpuscle, which preferentially pass rapid changes in pressure, confer on the receptor neuron its normally phasic response. (Randall, Berggren, French, 1997) This behaviour explains why the sensation of the coin was lost after a few seconds. The added coin did not produce enough mechanical force to excite the Pacinian corpustle once again, thus it was not felt. The time taken for the coin to stop being felt varied from person to person. This could be due to the different amount of tissue between the skin and the nerve. The thicker the less the coin is felt and the quicker is sensation is lost. A mechanoreceptors  receptive field  is the area within which a stimulus can excite the cell. If the skin is touched in two separate points within a single receptive field, the subject will be unable to feel the two separate points. If the two points touched span more than a single receptive field then both will be felt. The size of mechanoreceptors receptive fields in a given area determines the degree to which detailed stimuli can be resolved: the smaller and more densely clustered the receptive fields, the higher the resolution. For this reason, the density of the Merkel nerve endings and Meissners corpuscles determine the sensitivity of the particular area. (Wang , 2007) From the results obtained the fingertip is seen to be the most sensitive and thus will have a high density of Merkel nerve endings and Meissners corpuscles. On the other hand the fore arm is seen to be one of the least sensitive and thus will have a small density of the nerves Besides physical contact detected by mechanoreceptors, more complex accessory structures are able to transfer mechanical energy to the receptive membrane. These most complex accessory structure associate with mechanoreceptive cells is the vertebrate middle and inner ear. Hair cells are found in all vertebrate animals including humans, and are extremely sensitive mechanoreceptors. They are responsible for transducing mechanical stimuli to electrical signals. They are found in several locations. For example, in vertebrate fish and amphibians, an external set of receptors are called the lateral line system. This system is based on series of hair cells that detect motion in the surrounding water and when stimulated produces an action potential as in the mammalian ear. This lateral line is, however, not present in mammals. (Hickman, Roberts, Keen, 2009) The ears of vertebrates perform two sensory functions. The organs of equilibrium perform like the statocysts in invertebrates that allow the animal to detect its position with respect to gravity. The organ of hearing provides formation about vibrational stimuli in the environment, thus detecting sound. (Hickman, Roberts, Keen, 2009) Sound waves enter the external ear of a vertebrate aided by the pinna and the tragus. The entire external structure has a function similar to that of a funnel, amplifying and then concentrating sound waves. Vibrations from sound waves cause changes in air pressure, which travel from the external ear, down the auditory canal, and then move the eardrum. The ear converts energy of sound into nerve impulses. The vibration of the eardrum causes the fluid of the cochlea to move. The basilar membrane containing the floor of the cochlea, and the scala media, containing the organ of corti is where these vibrations undergo the conversion to neuronal impulses. The organ of corti contains sensory hair cells, and the waves of fluid in the cochlea press the hair cells against an overhanging tectorial membrane, and then pull them away. These hair cells are just across synapses from sensory neurons, and this action provides a stimulus that opens sodium channels in the sensory cell membranes. This provides for an action potential in the environment of high potassium concentrations that the endolymph has. Auditory nerves located in a spiral ganglion carry the action potential to the brain. (Randall, Berggren, French, 1997) Invertebrates, such as the insects have ears located on their thoracic legs and are associated with respiratory passages, called the trachea. The ear tympanum has an analogous function to the tympanic membrane of the mammalian ear. Similar to a mammal, sound waves stimulate the membrane to vibrate, but in the insect, this directly activates nerve impulses. (Barnes Cawlow, 2002) Some insects also have a related tracheal system that directs information on air pressure changes, inside the insect, to the eardrum. If the right tympanum is stimulated, it will send the signal through the tracheae to the left tympanum. The delay in stimulus between the left and the right ear helps the insect locate the direction from which the sound came. Webers law states that the ratio of the difference threshold to the value of stimulus is constant. According to this relationship, doubling the value of the stimulus will cause a doubling of the difference in the threshold. As seen in the results the just noticeable difference or intensity difference for the 50 g and 100 g was seen to be constant for all the subjects. Chemoreception Vertebrates, including humans detect chemicals using general receptors and two types of specialized receptors, gustatory and olfactory. Many aquatic vertebrates have generalized chemical receptors scattered over their body surface. Vertebrates usually accomplish chemoreception by moving chemically rich air or water into a canal or sac that contains the chemical receptors. Mammals together with other vertebrate have taste receptor cells located in taste buds which are supported by basal cells. Chemoreception is much different in invertebrates than in vertebrates. For example, planarians find food by following chemical gradients in their surroundings. Their simple chemoreceptors are found in pits on their bodies, over which they move water with cilia. Insects have chemoreceptors in their body surface, mouthparts, antennae, forelegs, and, in some cases, the ovipositor. Moths, for example, smell with thousands of sensory hairs on their antennae. (Barnes Cawlow, 2002) Photoreception In vertebrates such as humans, the surface of the eyeball is made up of the sclera, a white connective tissue, and under that a thin pigmented layer called the choroid. The sclera contains the cornea which is transparent, and is where light initially enters the eye, and the choroid contains the iris which contracts and expands to regulate the amount of light entering the hole in its centre, known as the pupil. The rear internal surface of the eye is the retina, which contains the actual photoreception cells. In the retina, there are two types of receptor cells, rods and cones. Rods and cones contain visual pigments made up of light absorbing retinal molecules. (Randall, Berggren, French, 1997) Compound eyes of arthropods are image forming eyes composed of many optic units called ommatidia. These are able to detect a very small fraction of the spectrum of light that the eye as a whole is exposed to; like the rods and cones of the vertebrate eye. In compound eyes, the photoreception cells are called retinular cells, and they surround a single eccentric cell. Because the receptive field of each unit in a compound eye is relatively large, compound eyes have lower visual acuity than vertebrates. (Randall, Berggren, French, 1997) Thermoreception Temperature is an important environmental variable, and many organisms acquire sensory information about temperature from the action of specialized nerve endings known as thermoreceptors, in the skin. Both the external skin and upper surface of the tongue of mammals contain warmth and cold receptors. the warmth receptors detect an increase in temperature in the environment by increasing the firing rate transient. On the contrary cold receptors increase its firing rate transient when a cool environment is detected. (Randall, Berggren, French, 1997) These receptors are quite sensitive. Their firing rate is seen to increase the more the temperature of the external environment varies from the internal body temperature of about 37 OC. when the temperature becomes sufficiently different the patter changes for both types of receptors and the frequency of the action potential is seen to drop. The response of the thermoreceptors consists of a large transient change in firing rate, followed by a longer-lasting, steady-state phase. Other sensory structures that are not present in humans also exist. For example, snakes have thermoreceptors that are able to detect emitted heat energy. This is advantageous for them to detect warm-blooded prey. Also fish are able to use very low frequency electrical signals to communicate in murky water, thus they are able to locate each other. (Hickman, Roberts, Keen, 2009) Conclusion From this experiment it was concluded that different organisms have different sensory structures adapted to their unique modes of life. One could also not that as animals become more complex, their sensory structures are also seen to be more developed. This can be seen from the evolution of the simple eye spot in planaria to the complex eye found in humans. Not only are humans seen to be able to detect movement but also colour. However, one may also note that humans do not always possess the most advanced sensory structures. This can be seen in for example, the ability of reptile snakes to detect infrared radiation. This being absent in humans.

Wireless Networking And Malicious Association Computer Science Essay

Wireless Networking And Malicious Association Computer Science Essay Wireless security is to prevent unauthorized user to access the wireless network or damage the computer by using wireless network. When the wireless technology has been first introduced to the world, it already has few danger methods that will harm the users desktop or laptop, but that time cracker and hacker dont have any resources to crack or hack a network by using wireless technology. At that time, the wireless network only use by the big company. But now day, wireless network is very common, every corner of the world like cafà ©, shopping mall, school, or college that has provide wireless access for the people to access it. Not only cafà © and college using wireless network, at other country it use wireless technology to connect whole citys network. With this technology, people that around the wireless router can easily to access the wireless network to do the search of the information, check mail or play online game. Because of the wireless technology, now day, every laptop has wireless adapter card pre-install inside and make the laptop more portable and let them can connect to internet easily. Not only for laptop, wireless technology also make benefit for the desktop. Desktop can connect to network by installing a wireless adapter card or plug in an USB wireless adapter then desktop can connect to a network and without cable messy around the floor. In this case, wireless technology has become widely use and because of this reason, the risk of using wireless technology has increase and let many hacker found the way to hack the wireless network. All of security risk is related to the current wireless protocol and encryption method. Most of the wireless networks use IEEE 802.11b for standard communication and IEEE 802.11b have already became standard wireless networking technology among the small business user and home user. The IEEE 802.11b can support the indoor distance from several meter to several hundred meters, and can support the outdoor from several kilometer to several ten of kilometers by using unlicensed wireless band. Now day, the wireless network devices normally are equipped with Wired Equivalent Privacy (WEP) data encryption. WEP data encryption was based on 64-bit RC4 encryption algorithm. Other that 64-bit RC4 encryption algorithm, 128-bit encryption algorithm is another data encryption on the WEP data encryption. But this kind of device is more expensive compare with 64-bit RC4 encryption and beside that, all the nodes must use the same encryption level. 1.2 Aim of Research Aim of the research is to implement the wireless security into the CSC System to prevent unauthorized user to access the wireless network. To increase the security level of the wireless network. To avoid the data or information inside the server or computer been hacked by unauthorized user. To increase the safety of the data transfer between server and computer. To add extra encryption method to encrypt the packet need to be transfer. To prevent unauthorized user to shut down whole system though the wireless access point. Chapter 2: Main Body 2.1 Wireless Security Concept A research has been carried out about the concept of the Wireless Security and how to enhance the wireless security. Wireless Security is to prevent an unauthorized user to invade the server database and bring harm to entire network. Below are the results of the research. 2.1.1 Unauthorized Access According to the research, have a lot of way to break into the wireless access point without an authorization. The unauthorized access will cause companys daily operation failure and lose profit. Below are the some of the examples unauthorized accesses. 2.1.1.1 MAC Spoofing MAC spoofing is a technique to change an assigned MAC (Media Access Control) address to another different MAC address. When a person using this technique, he/she has his/her reason to changes a network devices MAC address, whether is legitimate or illegitimate. Changes a network devices assigned MAC address allows bypass the access control list on the server or router, either hiding a computer on a network or attacking a network by simulate another network device. MAC spoofing occurs when a cracker or hacker has the ability to listen the network traffic that passed by and through it; the cracker or hacker can identify the MAC address of the computer with network privileges. Most of the wireless system allows MAC filtering to only allow authorized computer that with specific MAC address to access the network. The computer that dont has specific MAC address cant access the network, so the cracker or hacker use a program which has network sniffing capability and combine with other software or program to pretend the computer has any MAC address that the cracker desires. (Wikipedia, 2010) 2.1.1.2 Malicious Association The Malicious Association is hacker that can connect to company network by using their cracked laptop. This type of laptop is known as soft AP (Access Point) and this type of laptop is created by using some software that makes the hacker laptops wireless adapter card look like a legitimate access point. After the hacker has already gained the access to the company network, the hacker can steal the password or plant the computer virus into the network. (Wikipedia, 2010) 2.1.1.3 Ad-hoc Network Ad-hoc network, also known as peer-to-peer network built up between two or more wireless computers and these wireless computers dont have access point in between them. Ad-hoc network usually provide little protection, encryption method to the network. When a company or person using Ad-hoc network and wired infrastructure network together at the same time, and will link up a secured network to an unsecured network. Connect two different network topology need to have a bridge between them. Bridging is in two forms. User can connect the network topology y a direct bridge and indirect bridge. Direct bridge need to configure by the user and indirect bridge is user share resource on the user computer. The indirect bridge is provides two security problems. The first problem is the data can be obtained through the secured network on the user computer and this data exposed to other user discovery via the Ad-hoc network bypassing the user secured network. The second problem is a Trojan, computer virus or worm can be placed on the user computer through the Ad-hoc network. The unauthorized user no needs to crack the password of the network and can place the computer virus through the Ad-hoc network. (Wikipedia, 2010) 2.1.1.4 Denial of Service C:UsersZoukyDesktop424px-Stachledraht_DDos_Attack.jpg DoS (Denial of Service) or DDoS (Distributed Denial of Service) will occurs is when an attacker continues non-stop bombards an attacker targeted access point with bogus request, failure messages, or other commands. Denial of service will cause other users cant get into the network and also will cause a network crash. The DoS attack will expose a little bit of the data to the attacker, when the DoS attack happen, the interrupted network will prevents the data flow and also indirectly prevent the data from being transmitted. After the DoS attack has been performed, the attacker will start to observe recovery of the wireless network. During the initial handshake code is start to re-transmitted to the wireless network, the attacker continue what he remain. The attacker will record down the initial handshake code and use cracking tools to analyze the security weakness and exploit this code to get an unauthorized access to the system. (Wikipedia, 2010) 2.1.1.5 Man-in-the-middle Attack Man-in-the-middle attacker using a computer to sets up a soft AP (Access Point) and enticing other computers to log into the computer that already been sets up to soft AP. After this all are done, the attacker connects to a real access point by using other wireless card and the attacker will offers a steady flow of the network traffic through the done hacking computer to real network. Man-in-the-middle attack forces other computers AP drop the connection to real network and reconnect to attackers soft AP. This allows hacker to receive what other computers want data need to send out to real network. (Wikipedia, 2010) 2.2 Basic Security for Wireless Wireless network exist in this world already has a decade, at that time the security for the wireless network still not strong enough to prevent infiltrate by hacker or cracker. But at that time the hacker doesnt familiar on technology or technique to hack the wireless network. One of the reasons is the hacking device to hack the wireless network still hard to achieve on that time market. After a decade, the technology and technique to hack a wireless network and the step to build up the hacking device can found on internet. So now day the wireless network users need to have a strong and better wireless security to secure the wireless network. Below are the basic securities for wireless network for the first wireless network has been introduced. 2.2.1 Service Set Identifier SSID (Service Set Identifier) is a common network name for a device in a wireless LAN and some of the wireless device has its own default SSID. The default SSID can be replaced by other string and normally this string is generated randomly. SSID is to identify a name for particular wireless access point. All wireless network need to have SSID within the wireless access point just can communicate each other. The client doesnt know the SSID of the access point, then that client cant simply access the network; this is to prevent hacker to invade network by access through access point. The hacker need to know the SSID of a network just can complete the 802.11b protocol to access the network. The access point will broadcasts the SSID by the beacon inside the wireless device. However, even the broadcasting of the access point is turn off, the SSID still can detected by hacker with undetected monitoring of particular network or sniffing. So, all the clients need to know the SSID of the acce ss point before can make connection to the wireless device. (Bhagyavati, Wayne C. Summers and Anthony DeJoie, 2004), (Prasad, 2007) 2.2.2 Medium Access Control Address Filter Each wireless access point can be configured only accept the clients MAC address that already registered inside the wireless access point. With this function, the network administrators can limit the access of the client into wireless network by register the clients MAC address into the wireless access point. Most of wireless devices MAC address is unique and MAC address filter only allow the clients MAC address already registered in the wireless access point to access the network. The entire clients MAC address will store into MAC address ACL (Access Control List) and wireless access point will denied other wireless device if the wireless devices MAC address is not register inside wireless access points MAC address ACL. (Bhagyavati, Wayne C. Summers and Anthony DeJoie, 2004), (Prasad, 2007) 2.2.3 Wired Equivalent Privacy WEP (Wired Equivalent Privacy) is intend to give wireless users have a security scheme is equivalent to the wired network security. WEP doesnt provide any superior level or higher than that level of security, although WEP doesnt has superior level of security but it security level is equivalent with wired network. In the practice, the result show that the security level of WEP need to equivalent to wired network security is hardly to achieve. The use of WEP is to prevent the wireless client from sending and receiving data from the wireless access point, the wireless clients need to have the correct WEP key just can connect to the wireless access point. Now mostly of the network devices is equipped with the WEP data encryption and the encryption algorithm for the WEP is 64-bit RC4. Some of the network device capable to uses 128-bit encryption algorithm. After WEP is active, each 802.11 packet will encrypted by 64-bit RC4 key with RC4 cipher stream. This key is composed of 24-bit IV (I nitialization Vector) and other 40-bit is WEP key. IV is chosen by the sender and the IV can be change, this make every packet wont encrypt with the same key. Another additional 4-byte is for ICV (Integrity Check Value); ICV is computed and appended on the original packet. RC4 cipher stream is generated by 64-bit RC4 encryption algorithm. The WEP encryption algorithms work on a key that share between wireless device and wireless access point. The packet is encrypted by using the key before packet is send out and all packets wont have same cipher stream. The packet receiver use integrity check to ensure that the packet is not modified during the transmission. Most of the systems are share a single key among all the wireless device and wireless access point. The Integrity Check Field is to ensure the packets are not been modified during the transmission and Integrity Check Field also encrypted with the RC4 cipher stream. WEP is using CRC-32 (Cyclic Redundancy Code 32) mechanism for i ntegrity check. CRC is defined as a class of checksum to prevent overflow by dividing the message into binary. (Bhagyavati, Wayne C. Summers and Anthony DeJoie, 2004), (Halil Ibrahim BulBul, Ihsan Batmaz and Mesut Ozel, 2005), (Prasad, 2007) 2.3 Comparison between SSID, MAC Address Control Filter and WEP From the research, SSID (Service Set Identifier), MAC (Medium Access Control) address control filter and WEP (Wired Equivalent Privacy) are the basic security for the wireless network. This three security methods can implement together in one network. Because these are basic security for wireless network, so the security methods are easy to break by unauthorized user. If not implement other security methods and only just implement SSID, MAC address control Filter and WEP into wireless network, that wireless network will not secure under protection of these three security methods. The wireless access point will broadcast the SSID to the wireless client and wireless client just can access to the access point. When the access point broadcast its own SSID, the entire nearby wireless client will know the SSID of that network or access point, even the unauthorized users also will know the SSID of the network. The unauthorized users will attempt to access the wireless access point. And the wireless access point can close the SSID broadcast function; mean that the SSID is hidden. But when the authorized user requires connecting to the access point, the authorized user will broadcast the SSID to the wireless access point, if the SSID broadcast by the authorized user is match with the SSID of the access point. The authorized user just can make connect to the access point. This make hacker a chance to hack the access point because when authorized user is broadcasts the SSID to the access point, hacker can capture the packet that broadcast by the authorized user and make connection to the wireless access point. The wireless devices MAC address will store inside the wireless access point ACL (Access Control List), the wireless devices MAC address need to be match with MAC address inside the wireless access point ACL just can connect with wireless network. If that wireless network has more than 20 computers need to connect to the wireless network, then the network administrator need to enter all the computers MAC address into the wireless access point ACL. This will make the network administrator very troublesome enter the MAC address one by one and MAC address can be forged. WEP has been considered as a failure in wireless security, at the end it still accepted by the IEEE because WEP wasnt aim for provides fully security for wireless. WEP encryption is very easy to crack by the unauthorized user. WEP only authenticates the wireless client. This allows an unauthorized user to capture the packet send by the wireless client. WEP key is easily lost or stolen by unauthorized user and if the stolen WEP key hasnt been report to the network administrator, the network administrator wont able to detect the unauthorized user has already infiltrated the wireless network. If the stolen WEP key has been reported, network administrator require to change the entire devices that have use the same WEP key with stolen devices WEP key. If the company or enterprise has more than thousands of wireless user using that wireless network, this can be a very difficult task for the network administrator to change the entire WEP key for each wireless users. Like just mentioned, the WEP authentication message is easy to forging by the unauthorized user. Unauthorized user can capture the authentication message that send by the wireless client and forge a new authentication message; unauthorized user can use this forged message to associate with wireless access point. The management for WEP key in not specific in WEP standard. Since dont have management for WEP key, then WEP key will be use for a long term and lack of quality. Most of the wireless network uses one WEP key and share between the entire network and the entire wireless clients access point need to program with same WEP key. Because of this reason, network administrators rarely change the WEP key. SSID, MAC address control filter and WEP is basic security for wireless network; these methods still cant apply in wireless network. Just using SSID, MAC address control filter and WEP are not enough to prevent the security break. These methods require associate with other security methods to enhance the wireless security to prevent security break. 2.4 Advanced Security for Wireless From the research that carried out, advanced wireless securities are to replace the basic wireless security and improve what basic wireless security vulnerability. 2.4.1 Wi-Fi Protected Access WPA (Wi-Fi Protected Access) is a certification program that created by Wi-Fi (Wireless Fidelity) Alliance; WPA is a subset of the IEEE 802.11i. This technology is designed to response to the weaknesses that found in WEP. WPA will generate the key based on the master key and the master key never use by WPA. To encrypt the data, WPA is much more secure than WEP. Key management and updating in WEP is poorly provided, the secure key management is a built-in function in WPA. Mean that WPA can update and manage the key easily, not like WEP. If WEP need to manage or update the key, the network administrator needs to change entire wireless client key that has connection with the wireless network. WPA got one key only and that is master key like just mentioned, network administrator only require to change that master key then WPA will generate the key based on the master key. Generated key is hierarchy of the master key. So this make the management and updating become much easier. The IV (Initialization Vector) values can be reuse and the length of the IV is become longer, from 24-bit increase to 48-bit. Another additional part, the IVs are the sequence counters for the TSC (TKIP Sequence Counter), to protect the loop of the data. The WEP message integrity protocol CRC-32 has been proved ineffective. Because of this reason, WPA uses a MIC (Message Integrity Check) mechanism to replace the WEP message integrity protocol. The correct MIC is very difficult to guess. (Halil Ibrahim BulBul, Ihsan Batmaz and Mesut Ozel, 2005), (Bhagyavati, Wayne C. Summers and Anthony DeJoie, 2004), (DifferenceBetween, 2010) WPA has 3 improvements over WEP: Improved Data Encryption WPA improves the data encryption through the TKIP (Temporal Key Integrity Protocol). TKIP generates the key by using hashing algorithm and adding the integrity checking feature, this will ensure the key havent been edited by other person. TKIP is a Temporal Key hash Function and it is another option to WEP to fix all security problems that WEP has and it doesnt require installing other new hardware. TKIP same like WEP, use RC4 stream cipher to encrypt and decrypt data and all involved clients require share the same key. This key must be 128-bit and it calls Temporal Key (TK). The Initialization Vector also include in TKIP. Even if the TK is shared among all the wireless clients, all wireless clients generate different RC4 key stream. Since the communication participants perform a 2-phase generation of a unique Per-Packet Key (PPK), which is used as the key for the RC4 key stream. (Halil Ibrahim BulBul, Ihsan Batmaz and Mesut Ozel, 2005) User Authentication User authentication in WPA is through the EAP (Extensible Authentication Protocol). This function is missing in WEP and WEP access to the wireless network is based on computers network cards MAC address and MAC address is very simple to be stolen. The purpose of EAP is to create a more secure public-key encryption system to ensure that only authorized user can access the wireless network. (Halil Ibrahim BulBul, Ihsan Batmaz and Mesut Ozel, 2005) Integrity WPA has a new mechanism call (MIC) Message Integrity Code for TKIP is computed by a new algorithm, name Michael. MIC is computed to detect errors in the data contents, either is transfer errors or purposely change the data content. The Michael is a 64-bit MIC and need to add to the data and ICV (Integrity Check Value). (Halil Ibrahim BulBul, Ihsan Batmaz and Mesut Ozel, 2005) 2.4.2 Robust Security Network RSN (Robust Security Network), also call as WPA (Wi-Fi Protected Access) 2. At year 2004, concept of RSN has been released, where the wireless devices need to support by additional capabilities. RSN is fully tested by Wi-Fi Alliances. RSN has a whole new standard and architecture to utilize the IEEE 802.1X standard for AES (Advanced Encryption Standard) and access control. RSN is using a pair-wise key exchange (Four Way Handshake) protocol, RSN also utilizing with 802.1X for key management process and mutual authentication. Now, 802.11i allows for the network implementation and also can use TKIP (Temporal Key Integrity Protocol). By default RSN uses CCMP (Counter Mode MAC Protocol) and AES (Advanced Encryption Standard) to provide for a scalable and stronger solution. AES is a replacement for RC4. Data transmission between the wireless access point and wireless device, RSN uses encryption algorithms and dynamic negotiation of authentication on the data transmission. The authentication of RSN is based on 802.1X and EAP (Extensible Authentication Protocol). Encryption algorithms and dynamic negotiation of authentication make RSNs security more secure and save. RSN is stronger and better than WEP and WPA because RSN is using dynamic negotiation, 802.1X, EAP and AES. Unfortunately only the latest devices have the capability let RSN to accelerate the speed of algorithms calculation in wireless client and wireless access point; now day of wireless product cant fully provide the performance of RSN. (Halil Ibrahim BulBul, Ihsan Batmaz and Mesut Ozel, 2005), (Bhagyavati, Wayne C. Summers and Anthony DeJoie, 2004), (DifferenceBetween, 2010) 2.5 Comparison between WPA and WEP WPA (Wi-Fi Protected Access) is the solution for the WEP vulnerability, has some critics done for the WEP, the WPA has numerous enhancements over WEP. WPAs TKIP encryption algorithm has fully enhances the WEPs RC4 encryption algorithm. TKIP make the data encryption more efficient and replace the RC4 vulnerability. WPA has made the key management became much more easier compare with WEP, because the WEPs key require enter one by one to the wireless client, if the company has more than thousands users then the network administrator need to enter more than thousands keys into the users computer. If the key is hacked by unauthorized user, then network administrator need to change key for entire companys computers. On the other hand, WPA no needs so troublesome, WPA only needs to enter one master key, and then WPA will generate key according with the hierarchy of master key, after that WPA will assign the key to the clients and the key is generated in 48-bit of IV size. Even the company g ot more ten thousands users also no need to trouble the network administrator. If one of the key has been hacked by unauthorized user, TKIP just need to generate a new key then network administrator can info the wireless client to change the key. WPA has EAP to authenticate the wireless user. WEP is using MAC address to authenticate the wireless user and some of the wireless devices MAC address can be forged. If the wireless devices MAC address has been forged by unauthorized user then the unauthorized user can easier to connect the wireless network without known by the network administrator. Network administrator also wont notify the wireless network is infiltrated by the unauthorized user until the wireless user report there is a missing MAC address. WPA is using EAP to authenticate the wireless user and the EAP for each wireless client is hard to forge by unauthorized user. If the EAP of the client is forging, but the unauthorized user still need wireless clients private key just can access the wireless network. WEP dont have error checking for the data content, and this will cause the looping of the data. If cant prevent replay attacks and will cause the wireless network crash. WPA has inserted the MIC into TKIP and IV sequence mechanism; this is to prevent replay attacks in the wireless network. MIC and IV sequence mechanism support for the existing wireless infrastructures not require installing new wireless device. Adding MIC and IV sequence mechanism without install new wireless device, adding these two methods can increase the wireless security and also without increase the installation cost of wireless device. Compare WPA with the WEP, WPA has solved a lot of WEP vulnerabilities. This make WPA is more secure compare with WEP because WEP only is basic security for the wireless network; it doesnt provide any protection for the wireless network. WEPs security methods can let a small enterprise to setup a small wireless network. For the big company, WEPs security methods are hard preventing the unauthorized access from outsider. 2.6 Comparison between WPA and RSN For now, never the less, RSN (Robust Security Network) is the strongest wireless security protocol for the wireless network. RSN provide stronger data encryption algorithm and all advantages of WPA. The RSN data encryption algorithm method is using AES (Advanced Encryption Standard) to encrypt the data. What advantages WPA have all included in RSN, expect the RSN data encryption algorithm is more advance. For WPA require upgrade for the software and firmware of the wireless device for the existing wireless network infrastructure, but the RSN doesnt support existing wireless network infrastructure, require upgrading the wireless device in order to implement AES. Implement RSN into the existing wireless network infrastructure require extra cost for just upgrade the hardware. RSN need large amount of processing resources in order to protect the wireless network. Mean that implement RSN will reduce the wireless network performance by processing the data transfer or verify the wireless client. 2.7 Table of Comparison between WEP, WPA and RSN Below is summary of the comparison between WEP, WPA and RSN: Features of Mechanism WEP WPA RSN Encryption Cipher Mechanism RC4 RC4 / TKIP AES / CCMP CCMP / TKIP Encryption Key Size 40 bits 128 bits 128 bits Encryption Key Management None 802.1x 802.1x Encryption Key Per Packet Concatenated Mixed No need Encryption Key Change None For Each Packet No need IV Size 24 bits 48 bits 48 bits Authentication Weak 802.1x EAP 802.1x EAP Data Integrity CRC 32 ICV MIC (Michael) CCM Header Integrity None MIC (Michael) CCM Replay Attack Prevention None IV Sequence IV Sequence (Halil Ibrahim BulBul, Ihsan Batmaz and Mesut Ozel, 2005) Chapter 3: Conclusion 3.1 Achievement of Objectives 3.1.1 To increase the security level of the wireless network. In chapter 2.2 until 2.4, the different wireless securities provide different service. 3.1.2 To avoid the data or information inside the server or computer been hacked by unauthorized user. In chapter 2.1, the type of the unauthorized user that can infiltrates the wireless network and chapter 2.2 and 2.4 the methods to prevent hacking. 3.1.3 To increase the safety of the data transfer between server and computer. In chapter 2.2 until 2.4, increase the safety of the wireless access point of wireless network. 3.1.4 To add extra encryption method to encrypt the packet need to be transfer. From chapter 2.2 until 2.4, the extra encryption methods that can hide the data detail. 3.1.5 To prevent unauthorized user to shut down whole system though the wireless access point. In chapter 2.2 until 2.4, the methods to prevent the unauthorized user to connect with wireless access point. 3.2 Research Conclusion A research has been carried out to finish this seminar report by studying the type of the unauthorized access, concept of the wireless security and how efficiency is the wireless network security by determine the wireless security method. Now wireless has already became widely use by company or enterprise, even at home also can using wireless to connect to internet for home purpose like surfing the internet. The reason why so many people like to use wireless network compare with wired network, is because the structure of wireless network is more neat and easy to manage. At the time wireless just came out to the market, the security for the wireless still breakable by hacker or cracker but need a lot of resources to break the security of wireless network. Because last time, wireless network just introduced, the hacker or cracker lack of technology and technique to break the wireless network. Still after few years, the technology and technique to break the wireless security can found in internet. At that time the wireless network has sound the alert and organizations are finding the solution for solve the wireless security problem. But now, the new technology of wireless security has out to market and the security methods are easy to install. So, now wireless security is not a problem. In the report got mentioned is RSN can be the most dependable wireless security for the wireless network. But it still has certain problem like higher cost. Installation for the RSN needs to change whole wireless network infrastructure. WPA got a lot of security methods that cant compare with RSN but WPA still dependable just like RSN. Doesnt mean the expensive item is the good item. As long as the item is reliable then that item is a good item.

Essay --

â€Å"In July 1945, the first atomic bomb was tested in New Mexico and the next month the second and third weapons off the production line were dropped on Japan. Since then no nuclear weapons have been used in anger, although tens of thousands have been accumulated by the major powers and their destructiveness and sophistication increased immensely.† The nature of warfare is constant and evolved from multiple factors and military revolutions over time. The purpose of this paper is to identify the most important military revolution in history and highlight its effects that permeate modern day society. The proliferation of nuclear weapons is the most significant military revolution that led to the greatest changes in warfare, which include the immergence of new threats such as non-state actors, the shift from total war to low intensity conflict, and the importance of technology and innovation. This military revolution completely shattered existing paradigms of warfare due to th e real threat of nuclear weapons’ total destruction of humanity. The arrival of nuclear weapons transformed the international playing field permanently and new threats such as non-state actors have immerged as a result. Initially, only superpowers with nuclear arsenals had a global role as was evident during the Cold War between the U.S. and Soviet Union, but nuclear proliferation triggered a race to possess this power in the last 60 years. The possible employment of nuclear weapons between the two superpowers during the Cold War was unprecedented. The power of this stalemate shattered the paradigm of warfare and demonstrated how significant this military revolution’s effects were even at the mere threat of nuclear weapons use. Regarding this standoff between t... ... examined the importance of the nuclear weapons military revolution and its lasting impacts on modern day society. Evidence presented supports why this military revolution had the most impact of all on warfare and was carefully illustrated through the immergence of new threats, the shift from total war and high intensity conflict to low intensity conflict and finally, the critical role that technology and innovation has played since the advent of nuclear weapons. This is important in today’s operational and strategic environment due to the fact that American military and political leadership will continue to have taken in account the use of nuclear weapons on the battlefield. As globalization continues to set the conditions for nuclear weapons proliferation worldwide, the restraints and operational risks will dramatically increase and affect all strategic planning.

Beyond Cybersex †The Search for Intelegent Life on the Internet :: Exploratory Essays Research Papers

Beyond Cybersex – The Search for Intelegent Life on the Internet Big Beautiful Women, 25 Bi & Curious F4M, The Tavern of Goth, BBW 4 Sexy Chat, Naked M Needs Help Stroking. These are just a few of the "tamer" examples of user-defined chat rooms I popped into in my search for interesting people to talk to online. Fortunately, I found that there are people online who are looking for more than cybersex. From World Wide Web based chat rooms to personal programs such as   ICQ (short for "I seek you"), there are many avenues to meet people online. There are also many different types of people to meet. One can chat with people sharing specific interests, but for the adventurous, random chatting is also possible. Having several friends who enjoy chatting online, I have heard many stories about interesting people they have met. On the other hand, I have also heard stories about all the people who are simply looking for cybersex. Sensing my skepticism, a friend of mine told me about someone he met online, and still talks to frequently. My friend works for a prominent Internet firm, and his responsibilities include popping in and out of the chat rooms as a silent monitor. However, once in a while, his love for chatting takes over. One evening he entered a chat room and decided to try some cheesy opening lines to see who’d bite. He picked a user with "angel" in her screen name. "What makes you an angel?" he asked. She answered, I feel as though I need closer guidance to God." Automatically, my friend thought she was weird, but as the conversation went on, he learned things about this woman that made him want to know more. He spent seven hours talking to her, and after their conversation they became online pen pals, who now consider themselves "cyberbuddies." Given hope to find somebody interesting, I sat down at my computer and connected to the Internet. Since I had already used ICQ to communicate with friends, I decided to use the random chat feature it offers. Within minutes, I received a message from someone who asked if I was male or female. When I responded that I was male, he didn’t write back. Hmm . . . I wonder what he was after. A little discouraged, I added a note to my personal profile on ICQ that said I was a male college student writing an article about the people one can meet online.

Freedom of speech :: essays research papers

Do Americans take the First Amendment for granted, or use it, as a clutch to say what they feel is appropriate. The First Amendment states that Congress shall make no law respecting an establishment of religion, or prohibiting the free exercise thereof; or abridging the freedom of speech, or of the press; or the right of the people peaceably to assemble, and to petition the Government for a redress of grievances. (Siegel 3) But what is Freedom of Speech? It is our ability to say what we want, when we want and to whom we want? But there are even restrictions on what we want to say for example a person cannot yell fire in a crowded movie theater. Like all situations there will be persons to disagree? The past presidential election put the nation in an uproar, as do all elections. But, non as controversial as this one. In this election the issues that were addressed split the county in two, half of the country having liberal views and the other half having conservative views. That was mainly the focus of the entire campaign. What is being liberal or being conservative? Liberals favor gradual reform, especially political reforms that extend democracy, distribute wealth more evenly, and protect the personal freedom of the individual. On the other end of the spectrum, conservatives are in favor of preserving the status quo and traditional values and customs, and against abrupt change(msn. Encarta) This seems to make Americans look weak to the rest of the world. That we don’t even have a common ground on the issues of the nation . This great nation that is seen as the mother country to the rest of the world is spilt right down the middle with labels that divide people. And that’s where it really gets ugly. Will Americans ever put these labels aside and come together so that America can be a better place to live? By being a graduating senior looking at the nation as either being liberal or conservative has made me really take a look at myself and my beliefs on the issues .