Manuscript Introduction and Methods Sections Essay

Manuscript Introduction and Methods Sections - Essay Example Indeed, such a compound might prevent the occurrence of the withdrawal phase and dysregulation of the reinforcement mechanism that is known to be involved in compulsive smoking. Tobacco smoke contians several substances. Of them, nicotine appears to be the critical reinforcing component of tobacco smoke. A large body of evidence implicates a4b2 nAChrs in the reinforcing effects of nicotine. The initial effect of nicotine is probably to activate 42-nicotinic acetylcholine receptors located on dopamine neurons in the ventral tegmental area; however, it is likely that these receptors are rapidly desensitized, whereas nicotine produces a sustained effect on dopamine release in the nucleus accumbens (Foll and George, 2007). Bupropion and varenicline are accepted as therapy for niocotine addiction. Bupropion can block nicotinic receptor function. varenicline however is a partial agonist or an antagonist depending on the state of activation of the a4b2 receptors. Through its intrinsic partial activation of the 42-nicotinic acetylcholine receptors, varenicline may elicit a moderate and sustained increase in mesolimbic dopamine levels, which would counteract the low dopamine levels encountered in the absence of nicotine during smoking cessation attempts.

OSI Layer Assignment Example | Topics and Well Written Essays - 1750 words

OSI Layer - Assignment Example However, other similar system programs are not included in the scope of OSI model; however they perceive an end user's typing into a Layer 1 demand (Holmes, 2011; RingofSaturn, 2011). In other words, the application layer works as an interface between users and network. Thus, it allows the users to access network operational services. In addition, this layer holds a multiplicity of required processes: (Microsoft, 2011)   5 PRESENTATION LAYER 6 The presentation layer offers a range of encoding and encryption processes that are applied to the data received from application layer. The purpose of these processes is to make sure that information received from the application layer of one system will be understandable to the application layer of another system. In addition, it works as a translator of the network since it translates the data to be accessible to the system’s application layer. ... In this scenario, the complexity and size of a network transport protocol completely depends upon the kind of service which is presented to it by the network layer. In addition, for a trustworthy network layer with virtual circuit potential, a negligible transport layer is necessary. On the other hand, if the network layer is untrustworthy and/or simply facilitates datagram transitions method, the transport protocol should encompass widespread error discovery and recovery methods.  Moreover, the transport layer is responsible for carrying out following tasks: 8 NETWORK LAYER 9 Network layer offers freedom from data transfer technology and routing concerns, masks peculiarities of data transport medium from higher layers and offers switching and routing processes to create, uphold, and end network layer links and transfer data among various users. In this scenario, the network layer is mainly responsible for controlling the processes of the subnet, and making a decision that which ph ysical path the data should be based upon, main concerns of service, and other aspects. In addition, network layer of OSI model carries out following tasks: (Fairhurst, 2001; Fairhurst, The Internetwork Protocol (IP), 2008; Microsoft, 2011) 9 DATA LINK LAYER 10 The data link layer is the place where logical data and information (for example network IP addresses) are actually interpreted into the electrical pulses that move over the physical layer. In addition, ATM, Frame Relay and DSL follow Data Link layer mechanisms. Additionally, the OSI model data link layer offers error-free communication of data frames from one node to another network node over the physical layer, permitting layers above it to suppose virtually error-free data and network