Cannabis and its Effects on Long Term Memory

The use of cannabis is often associated with memory challenges in the short term and long term basis. Studies continue to be carried out to determine if chronic cannabis use affects long term memory by examining variety of cognitive functions. This paper reviews related literature on memory dysfunction in cannabis users (Parath, 2009).Advertising We will write a custom research paper sample on Cannabis and its Effects on Long Term Memory specifically for you for only $16.05 $11/page Learn More The literature reviews includes studies that looked at memory function in cannabis users of chronic intoxication period (Austin, 2010). Specifically, it examines studies in working memory and verbal episodic memory. In addition, they have continued to deduce evidence indicating impaired encoding, storage, manipulation and retrieval systems in long term cannabis users (Allhoff, 2010). Cannabis is extracted from the plant Cannabis sativa. Usually, Cannabis is taken i n the form of dried leaves and female flower heads, or the resin secreted by these. This drug can be eaten, but is more usually smoked in the form of cannabis cigarette, or joint, often mixed with tobacco, or in pipe. Cannabis is an illicit drug that is commonly consumed in Europe and approximately 10% of adults aged 16-59 years in the UK used it in the year 2000 (Solowij, 1998). Majority of cannabis users attribute short memory problems as the most prevalent and this forms part of the reason many of them seek help to quit or reduce its consumption. Scientific literature in general avers memory impairment as often cited in relation to cannabis use (Wilson et al., 2002). Cannabis use has risen to become the most widely used drug in the developed world over the years. The memory function in general has been studied in acute administration studies of long term users of cannabis to humans and animals, and in long term studies of cannabis users (Pope et al., 2002). Cannabinoid System and Memory Endogenous Cannabinoid system is directly involved in the necessary functions of memory. This is because cannabinoid receptors happen in high density in brain areas critically involved in memory functions. Profoundly, cannabinoid affects synaptic plasticity underlying learning and memory, disrupting long term potential in hippocampus (Martin-Santos, 2010). Cannabinoid receptors are metabotropic receptors which are the most common in the brain and are involved in multiple physiological and behavioural events. They are found on pre-synaptic terminals in locations concerned in cognition, especially learning and memory, critically in hippocampus, prefrontal cortex, anterior cingulated, basal ganglia and cerebellum (Miller, 2010).Advertising Looking for research paper on psychology? Let's see if we can help you! Get your first paper with 15% OFF Learn More Endogenous cannabinoid system guides the flow of information in the brain through retrogrades signalling, modul ating inhibitory and excitatory neurotransmitter release critical for synaptic plasticity, depolarisation-induced suppression of inhibition or excitation, long term potentiation, and hence learning, memory and other higher cognitive functions (Kanayama et al., 2004). Structural Brain Changes Related with Chronic cannabis use There is lack of concrete lack evidence in most undertaken indicating that structural brain alterations in cannabis users. There are no global or regional alterations in brain tissue volume or composition in some recent studies (Ries, 2009). Other studies have discovered grey and white matter density alterations globally or in para-hippocampal areas. Utilizing more sensitive measures and assessing cannabis consumers with greater exposure to cannabis than previous research, critical reduction of hippocampus and amygdale volumes in long term cannabis users have recently been reported (Lyketsos et al., 1999). Hippocampus volume reduction was related to dose, correl ating with current daily dose, and cumulatively. Only excessive daily doses over long period of time, will lead to structural changes. Another critical factor may be the age of onset of cannabis use. This has a devastating impact to the brain, specifically cannabis consumers’ start at the early stages of neurodevelopment (Allhoff, 2010). Evidence adduced recently of reduced neuronal and axonal integrity in the dorsolateral prefrontal cortex represented by magnetic resonance spectroscopic markers of metabolism (Solowij, 2009). Changes related to dose were found in anterior cingulate and globus pallidum, but not in hippocampus. Solid evidence for dose related cumulative neuronal damage, neuronal and synaptic density. Since functional dysfunction is likely to precede major structural changes in the brain, or to show concomitant to more minor neural alterations. This presents good reason to think that long term effects of use of cannabis on memory function (Wilson et al., 2002). A Review of Related Literature: Effects of Cannabis Use on Cognitive ability in the long term Cannabis has the ability to exert prominent effects on the central nervous system. In the central nervous system, cannabis acts on an endogenous cannabinoid system that is concerned with regulation of mood, memory, emotion, attention, and other cognitive functions (Hall, 2009).Advertising We will write a custom research paper sample on Cannabis and its Effects on Long Term Memory specifically for you for only $16.05 $11/page Learn More Cannabinoid receptors play a significant role in memory storage and retrieval processes. Discoveries from human and animal research reveal that prolonged use of cannabis changes the functioning of the cannabinoid system of the brain. However, this does not lead to serious impairment (Solowij, 2002). Observation for structural brain impairment for in humans following long term cannabis use has not been sustained generally. Some cu rrent research has discovered no global or regional alterations in brain tissue volumes. Other studies have however, shown grey and white matter density changes world wide undertaken to date lack evidence of changes in structural brain in cannabis users or in para-hippocampal areas (Wilson et al., 2002). A recent study that used unique techniques of measurement to indicate that frequent but relatively short term use of cannabis creates neither structural brain abnormalities nor global or regional alterations in the brain tissue volume or composition that are assessable by magnetic resonance imaging (MRI) (Pope et al., 2002). Several studies have indicated altered brain function and metabolism in humans due to acute and chronic use of cannabis using cerebral blood flow, positron emission tomography, and electroencephalographic methods. In sum, use of cannabis has deleterious effects on memory and attention (Solowij, 2009). Individuals who use cannabis show clear signs of cognitive im pairments relative to controls. More of concern about cannabis is that its use may cause neurological damage resulting in persistent cognitive deficits, but the evidence is currently inconclusive. The evidence, however, does suggest that early use of cannabis may cause long-term cognitive problems (Solowij, 1998). Chronic Use of Cannabis and cognitive Dysfunction Cognitive dysfunctions or impairments, specifically deficits in short term memory, are reported by many cannabis addicts who seek help to stop using cannabis, and are often advanced as one of the main reasons for needing to stop using cannabis (Allhoff, 2010). However, evidence provided from controlled studies shows that long term heavy use of cannabis does not appear to produce severe debilitating dysfunction of cognitive function like that produced by chronic heavy alcohol use (Ries, 2009). Nonetheless, there is evidence that long term or heavy cannabis users exhibit more subtle types of cognitive impairment that are dete cted in well controlled studies using sensitive measures (Lyketsos et al., 1999).Advertising Looking for research paper on psychology? Let's see if we can help you! Get your first paper with 15% OFF Learn More Earlier studies of the cognitive effects of chronic cannabis use have elicited major concern that cannabis users may have had poorer cognitive functioning than controls before they commenced to administer cannabis (Sadider, 2010). However, studies from the recent past have looked at this problem by matching users and non-users on estimated premorbid intellectual functioning or on test performance prior to the onset of cannabis use. These studies have revealed cognitive impairments associated with frequent and long term use of cannabis (Solowij, 1998). Frequent cannabis consumers were showed impairment in tests assessing verbal expression, mathematics, and memory. Heavy users of cannabis were more susceptible to interference, made more perseverance errors, had poorer recall, and indicated deficient learning compared to light users (Wilson et al., 2002). Solowij et al., (2002) discovered few dysfunctions when they compared neuropsychological performance of dependent, heavy cannabis us ers with an average 10 years of regular use to anon-user control group. Chronic cannabis users with a regular use averaging 24 years were discovered with impaired attention and had retarded memory in general with dysfunctional verbal learning. Both groups of users indicated impaired temporal judgment. Solowij (1998) in a series of earlier studies applied more sensitive measures of brain function to demonstrate attention impairments in short term users. Solowij et al., (2002) deduced that long term use of cannabis escalated memory impairment. Specific deficits in verbal learning, memory and attention continue to be the most consistently replicated impairments to cannabis users. These impairments are associated to the period, frequency, and cumulative dose impacts (Pope et al., 2002). Differential effects of the various parameters of cannabis use such as, frequency, duration and dose, have not been investigated consistently. As a result, studies are still ongoing to determine whether memory impairments should be related or associated to acute, drug dose, and others occurring the brain memory due to long term cannabis exposure (Solowij et al., 2002). Studies continue to be conducted to investigate the propensity for recovery of cognitive functioning following cessation of cannabis use. Solowij (1998) discovered partial recovery following median 2 years abstinence in a small group of ex-users performing a selective attention task. However, sensitive brain event related potential measures continued to indicate impaired information processing that was correlated with the number of years of cannabis use. Solowij et al., (2002) showed persistent dose associated decrements in neuro-cognitive performance after 28 days abstinence in heavy young users of mean age 20, 5 years use. According to pope et al., (2002), verbal and memory deficits persisted in those who had started using cannabis prior to the age of 17 years but not in those who commenced later in life. The sampl ed population was between the ages of 30 and 55 years at the time of research. This observation agrees with other observations of adverse effects in that beginning regular cannabis use before versus after the age of 17 years (Wilson, et al., 2000). There is still need for further studies to elucidate the effect of cannabis use in developing brain. Solowij (2009) reported that hippocampus, prefrontal cortex and cerebellum are main sections of endogenous cannabinoid activity and heavily implicated in the cognitive impairments associated with chronic cannabis use. Lyketsos et al., (1999) were able to report the only large scale prospective epidemiological study of the effect of cannabis use on cognitive functioning. They made assessments on cognitive reduction on the Mini Mental State Examination in 1318 adults over 11.5 years. They deduced no relationship between cannabis use and decline in Mini Mental state Examination score, and this persisted when adjustments were made for sex, age , education, minority status, and use of alcohol and tobacco. This study concurs with other evidence that cannabis does not produce gross cognitive impairment (Pope et al., 2002). Memory in Chronic Cannabis Users A cute administration of cannabis can disrupt the working memory. Animal literature exists that reports impaired working memory following acute and chronic use of cannabinoid, including an impaired delayed matching to sample tasks that resembles lesions or removal of the hippocampus (Azzam, 2010). A growing number of recent literatures have continued to study working memory and related functions in chronic cannabis users. Kanayama et al., (2004) examined spatial working memory in long term heavy cannabis users by using functional magnetic resonance imaging using relatively simple tasks. In this study non users made non significant more errors on the task, although few errors in both groups reflected the simplicity of the task and it has been suggested that performance defic its in chronic cannabis users are more likely to be elicited in complex tasks (Kanayama et al., 2004). In addition, Kanayama et al (2004) studies revealed that cannabis users exhibited widespread brain activation with enhanced activation of areas utilized in spatial working memory tasks. They interpreted their findings in terms of cannabis users experiencing subtle neuro-physiological deficits for which they compensate by working harder and calling upon additional brain regions to meet task requirements (Mack, 2010). In a study of abstinent adolescents aged 13-18, cannabis and tobacco smokers compared to tobacco only smokers (Hall, 2009). The group identified functional magnetic resonance imaging evidence of changed neuro-circuitry during the performance of an n-back auditory working memory task in the cannabis group, but only during nicotine withdrawal. Representative samples were tested twice, once during an ad libitum cigarette smoking condition, and again after 24 hrs abstention s from tobacco and cannabis users were in abstinence from cannabis for at least two weeks prior to testing. Cannabis users who abstained from tobacco revealed enhanced task biased activation, for instance, posterior cortical regions and others (Solowij, 1998). A study using real world functions approach examined mood and cognitive performance in a sample of workers with and without recent cannabis use, before and after work at the start and end of the working week. There were scanty details regarding cannabis levels in the sample. A verbal reasoning task was used to measure working memory. Other memory tasks encompassed immediate and delayed free recall and recognition of 20 words presented on a computer screen and a semantic processing task measuring speed of knowledge retrieval from general memory (Pope et al 2002). Poorer performance in verbal reasoning was apparent in cannabis users at the start of the working week and correlated and frequency of cannabis use. Lacklustre perform ance in verbal reasoning in delayed recall was found in cannabis users pre-work at the end of the working week and was correlated with duration of cannabis use. Cannabis users also indicated slower response organization and lower alertness than non-users, and slower psychomotor speed toward the end of the week, reflecting a lack of improvement in the speed over the working week in contrast to controls, rather than a progressive slowing by cannabis users (Solowij et al., 2002). Episodic Verbal Memory Verbal learning and memory have been the most impaired cognitive functions in the studies of acute cannabis use as well as in chronic cannabis users. Cannabis users experience impairments in cognition in terms of the period of cannabis use and the frequency of cannabis consumption, and lastly, the impact of cumulative dosage. Studies of acute cannabis use suggest that poorer performance can be seen in immediate and delayed recall of words. Recent studies have replicated dysfunction in le arning, recall, and delayed recall, with some evidence of rot. The studies deduced 17 hour abstinent long term chronic cannabis users recalled fewer words than shorter term chronic users and non user controls over learning trials (Roffman, 2009). Conclusion Satisfactory evidence has gathered from recent research of cannabis users in the unintoxicated state to conclude heavy cannabis use in the long term is associated with impaired memory function. This implies that impaired memory function goes beyond the period of acute use and is related to a variety of cannabis use parameters. Studies deduce memory impairments to increase proportionate to frequency, dosage, and cumulative dosage of cannabis administration. However, the exact that lead to memory deficits remain to be determined. A collection of research of cannabis users abstinent for reasonably long durations suggest that dysfunctional memory may persist for some time after acute use (Solowij, 2009). The overall evidence from the various reviews suggests that the use of cannabis does in a way affect negatively upon the function of memory. Greater deficits in memory may be apparent in tasks that are more complex and among chronic cannabis users. The kind of memory deficits in chronic cannabis users is not different to that observed under acute influence (Roffman, 2009). Heavy cannabis consumers in the unintoxicated state also indicate impaired immediate, but further delayed free call of verbal information, poor retrieval of information from memory, and difficulties manipulating the contents of the working memory. Memory recognition is inconsistently reported and dysfunctional (Sadider, 2010). Strategies of organizational nature within memory have not received sufficient research. Limited evidence is available for strategy use in spatial working memory. Several studies found similar dysfunctions in cannabis users in learning, on measures of immediate and delayed recall and to research where other verbal learn ing tests have been administered to cannabis users (Roffman, 2009). In sum, there exist a wide range of individual differences in the propensity to create memory impairment associated with long term chronic cannabis use. The effect of multiple interpersonal factors on resilience to and susceptibility to cognitive dysfunction deserves greater attention. Such factors may involve personality and differing genotypes. A perspective to substance use in general may also confer enhanced vulnerability to cannabis related cognitive memory and needs further attention in prospective studies (Allhoff, 2010). Generally, findings of changed brain activation from imaging studies of cannabis users suggest compensatory procedures activated to ameliorate cognitive deficits. A number of recent advances in techniques are beginning to interrogate pertinent questions; however, the field is still open for continued research. The specific nature of memory deficits in cannabis users has not been comprehensiv ely elucidated. Evidence exists for dysfunctional encoding, storage and retrieval (Roffman, 2009). Reference List Allhoff, F., Jacquette, D., Cusick, R. (2010). Cannabis. New York: Wiley Sons. Austin, L. (2010). Psychiatric and Mental Health Nursing for Canadian Practice. Sydney: Wolter Kluwer Health. Azzam, A., Yanofski, J., Kaftarian, E. (2010). First Aid for Psychiatry Boards. New York: Wiley Sons. Hall, W. (2009). Review Adverse Health Effects of Non Medical Cannabis. Elsevier, 374 Kanayama, G., Rogowska, J., pope, G., Gruber, A., Yurgelun-Todd, D. (2004). Spatial working Memory in Heavy Cannabis Users. Psychopharmacology, 176:239-47. Lyketsos, g., Garrett, E., Liang, K., Anthony, C. (1999). Cannabis Dependence. Cambridge: Cambridge University Press. Mack, A., Harrington, A., Frances, R. (2010). Clinical Manual for Treatment of Alcoholism and Addictions. New York: American Psychiatric Pub. Martin-Santos, R., Fagundo, A., Crippa, J., et al., (2010). Neuroimaging in Cannabis Use. Psychological Medicine, 40, 385-398. Miller, N., Gold, M. (2010). Addiction Disorders in Medical Populations. New York: Wiley Sons. Parath, A. (2009). Clearing the Smoke on cannabis. Canadian Center on Substance Abuse, vol.30 Pope, G., Gruber, J., Hudson, Huestis, A., Yurgelun-Todd, D. (2002). Cognitive Measures in Long Term Cannabis Users. Journal of Clinical pharmacology, 42, 41-47. Ries, R., Miller, S., Fiellen, D. (2009). Principles of Addiction Medicine. Sydney: Wolter Kluwer Health. Roffman, R., Stephen, R. (2009). Cannabis Dependence. Cambridge: Cambridge University Press. Sadider, P., Keshavan, M. (2010). Use as a Precipitant of Psychosis. Cambridge: Cambridge University Press. Solowij, N. (2009). Cognitive Abnormalities and Cannabis Use. Psychopharmacol, 23(3), 266-77. Solowij, N. (2002). Cognitive Functioning of Long Term heavy Cannabis Users Seeking Treatment. Journal of American Medical Association, 287(9), 1123-1131. Solowij, N. (1998). Cannabis and Cognitive Functioning. ICambridge: Cambridge University Press. Wilson, W., Mathew, R., Turkington, T., Hawk, T., Coleman, E. (2002). Brain Morphological Changes and Early Marijuana Use. J Addict Dis 2000; 19: 1-22. This research paper on Cannabis and its Effects on Long Term Memory was written and submitted by user Senator Kelly to help you with your own studies. You are free to use it for research and reference purposes in order to write your own paper; however, you must cite it accordingly. You can donate your paper here.

The Odyssey Essays - Mythology, Greek Mythology, Religion

The Odyssey Essays - Mythology, Greek Mythology, Religion The Odyssey The Odyssey The great muses are called upon by Homer to tell the great adventure of Odysseus in his travel back to his home. Prayers are given to the Greek Gods and muses by Homer in order to proceed this story. The Greeks life revolved around the gods in a matter of fashion as we presently revolve around Christianity. The depiction of the roles the gods played in the Odyssey is both presented in good and evil. The Greeks portrayed their gods as powerful and merciful. However in the Odyssey the gods play a role in a savior like Jesus Christ and the tormentor like Satan. With the present role in the story of Odyssey the gods can be seen as a key role in Odysseus life. Odysseus alone cannot have escaped the treacherous Trojan War without the aid of the gods. However can it be reconcile that the gods were truly the ones who controlled our lives? In Odysseuss case the gods played a vital role. Throughout the entire story Athena was the crutch Odysseus and his family leaned on in the time of aid. Through the treacherous paths Odysseus traveled it was hope of seeing Penelope and his son Telemachus that brought him strength and wisdom. With the loves one left behind Odysseus fearlessly face the gods and tramples over their challenges. Without the help of Athena and her wisdom and devotion to Odysseus his challenges would be help with no boundaries. With Athena on Odysseus side, he was able to return home without any harms done to him or his family. With the gods in favor of Odysseus return all he had to fight was the challenges Poseidon threw at him. With the water being the only road back to his home this challenge was fare more difficult then the Troj an War itself. With the guidance of Athena Odysseus was safely returned to Ithica. Even though Athena played a key role in Odysseus life she was still unable to protect him from the challenges he faced with Poseidon, Calypso, and Helios. The gods can be seen as Odysseuss sub-conscience. Athena being Odysseuss wisdom, Helios the jealousy hidden in our curiosity, Calypso the temptation we face, and Poseidon the challenges in life we face everyday. These main Gods played a key role in Odysseuss life. Poseidon tormented blinded Polyphemus. Poseidon would have never tormented Odysseus if only he kept his boastful self-quiet. A lesson in life learned by Odysseus to keep him self- humble at all times. Odysseus faced other challenges that slowed his journey towards home seem longer. Calypso who kept Odysseus on her island for seven years offered him the impossible. Odysseus with his wife in mind declined the gift for a passage towards home. With temptation and challenges that blockaded Odysseus journey hom e. However Odysseus and his deceased crew could of made it home safely if it wasnt for the curiosity and jealousy of the crew to open the bag of wind and their evil temptation to kill and eat Helios cows. The gods playing minor roles it was human nature that brought the crewmembers to their doom and slowed Odysseus down from returning home. Homer portrayed human nature with the gods and goddesses. We are our own enemy. We are the ones who lay the path in our life and destination. However there are bumps in the word that slow us down and break us down. With hope we resist temptation and fight evil off. The gods in the Odyssey portrayed the good and evil in human nature. Odysseus being the hero of the Odyssey resisted and learned valuable lessons in life on his adventure back home.

Criminal Justice Assignment Example | Topics and Well Written Essays - 250 words - 7

Criminal Justice - Assignment Example Most juvenile crimes result from the fact that they have not lived long enough to appreciate social norms and standards. Juvenile crimes therefore fall in the class of crimes with passion without forethought. They are still in their development stages and therefore may sometimes fail to differentia between right and wrong actions and as such commit criminal offences with little thought or understanding of probable consequences. As a result of their ongoing biological development, minors are unstable emotionally. Just slight provocations could therefore trigger emotions and causing them to react in violent manners. There is therefore lack of premeditation in most juvenile crimes and this justifies their preferential treatment by courts (Bonnie, Johnson, Chemers and Shuck, 2007). At the age of 16 and below, juveniles are still receiving parental care and therefore parents take responsibility for all their actions. Parents/guardians are charged with the responsibility of upbringing their children, availing healthy environment and instilling desirable values among the kids. The blame for juvenile crime should thus be shouldered by parents while the young ones receive preferential court treatment. This is because some juvenile crimes may be the result of circumstances such as being subjected to unsafe environment. The responsibility of their actions is therefore shifted to parents and courts prefer corrective rehabilitation on the juveniles. 1. Richard J. Bonnie, Robert L. Johnson, Betty M. Chemers and Julie A. Shuck. â€Å"Reforming Juvenile Justice: A Development Approach.† Washing, D.C: The National Academies Press, 2007. Retrieved at:

Management Managerial Process Essay Example | Topics and Well Written Essays - 1500 words

Management Managerial Process - Essay Example In fact, there is no technique or method that could ensure that a risk would not occur during the project. In this scenario, every project manager is well aware of the fact that they have to deal with a variety of risk all the way through the project life cycle. In the context of a project, a risk can be an action or event that can have an effect on the project. However, the nature of this effect can be either positive or negative. Additionally, a risk can have a cause and it takes place in the result of an event. For example, a cause can be related to changes in scheduling which can affect other activities of the project. In addition, the majority of the project risks can affect project duration, budget, schedule, and quality. Moreover, project risks are managed through project risk management approach. In this scenario, risk management is the process of identifying and managing project risks. Figure 1Risk Management Process, Image Source: (Gray, Larson and Desai 209) (Gray, Larson and Desai 207) presented a risk management model to deal with project risks. Figure1 presents a graphical representation of this model. This model is divided into different phases and each phase performs specific tasks. The first phase is risk identification where a detailed analysis is carried out on the project in order to determine the sources of risks. At this phase, the project management team determines the holes that can cause any risk during the project. Once this phase is completed this process moves to the next phase that is known as risk assessment. At this stage, the project management team further analyzes the identified risks. In this scenario, they analyze these risks on the basis of their severity level, probability and so on. For instance, if a risk occurs then what impact it will have on the project. After the completion of this phase, this process moves to the next phase that is known as the risk response and development phase. At this stage, a project management team develops the strategy or plan to deal with identified risks. At this stage, the project team finds the solutions to minimize the impact of these risks on the overall project. The last stage of this process is known as risk response control. This phase involves monitoring and controlling the project risk strategy (Gray, Larson and Desai 209). A risk is anything that may potentially hinder with successful completion of the project or business task (CIO Archive; Kerzner). A project can involve a wide variety of risks. Some of the well-known kinds of risk can include: Time Risk This kind of risks is very common in projects. In this scenario, the time duration for the completion of a project can increase, which can create various problems for the project management team such as the need for additional resources and budget. Cost Risk The majority of projects has fixed budget and the project team needs to complete a project within this budget limitation. However, in some cases, the pr oject budget can increase which cause various problems for the project. Legal Risk International projects involve the execution of project tasks in various countries so it can require compliance with laws and regulations of these countries. In case of not following these rules and regulations can cause serious problems for the project and organization. Technological Risks Some projects involve the implementation of latest tools and technologies.

Short report about living wall Essay Example | Topics and Well Written Essays - 1000 words

Short report about living wall - Essay Example Aside from the well-known Canadian Universities such as Waterloo and Queens, there are other Canadian installations of living walls. There are also a plethora of cost and environmental benefits to Nova Insurance, as well as physical and mental health benefits to its employees and clients. Loose walls are not recommended for Nova Insurance, as the plants are grown in the same manner as most house plants. They are in a pot of soil, which requires periodic replenishment and creates an untidy look that is also difficult to maintain in a public setting. Mat systems are created of a cork fibre or felt matting. This method will only support mature plant growth up to five years before reparation is required. This system requires constant irrigation as it is unable to hold water like loose media. This will create an additional cost requirement, as a hydroponics system is required. Structural systems are akin to a block type of system, which can be created in a plethora of sizes, thicknesses and shapes. This is the most recommended media, as they do not require renovation for up to 15 years. This type of system is most readily adaptable to architectural requirements of Nova Insurance, as well as most easily maintained and replaced as necessary. This system offers the highest longevity and performance among the three media. Overall, the structural media is often the most expensive to install initially, however, its maintenance cost is the lowest; longevity is the highest and the most vigorous in growth to achieve second floor expansion. Among varying universities across Canada, there are several other installations of living walls. One such installation is located in Richmond, BC at Vancouver International Airport. This living wall is both interior and exterior. This living wall was designed not only to be aesthetically pleasing, but also to assist the environment through

Surface-Enhanced Raman Spectroscopy (SERS)

Surface-Enhanced Raman Spectroscopy (SERS) Modern biomedicine advances have impelled the demand of sensitive, accurate and fast analytical techniques for biodetection and biodiagnosis. Many tools ranging from fluorescence spectroscopy, mass spectrometry or immunoassays have been used to resolve analytical problems related with health. Although these techniques are well established, several drawbacks still limit their fully applicability, e.g. prior sample preparation, time consumption or relatively low detection limits[1]. Recent developments in laser technology and nanoscience have converted surface-enhanced Raman spectroscopy (SERS) as one of the techniques with highest analytical potential. The SERS effect is associated to the intense electromagnetic field enhancements provided, upon light excitation, by localized surface plasmon resonances (LSPRs) at the surface of a plasmonic metal with features in the nanoscale range [2]. The Raman signal of the molecules in close vicinity to the metal substrate is enormously intensifie d, allowing sensing applications down to single-molecule [3]. Since its initial discovery, almost 40 years ago, the field of SERS spectroscopy has experienced an exponential growth, renewing the interest within the scientific community[4]. Among numerous potential applications, SERS has emerged as an ultrasensitive tool for detection and identification of biomolecules, such as DNA. [1, 5]. However, although a wide range of indirect SERS-based DNA approaches have been developed (mostly relying on the mediated capture of the target DNA and the use of extrinsic SERS reporters), the direct SERS spectral analysis of unmodified DNA still remains scarcely used, despite the fact that it provides specific, selective and complete vibrational information. The major limitation has been so far the lack of spectral reproducibility at low DNA concentrations. The investigation of the native structure of DNA (especially double-stranded DNA) based on its affinity towards gold/silver substrates was ma inly hindered by the phosphate backbone of DNA, since it is negatively charged at physiological pH. Recently, the spectral reproducibility issue have been addressed by different scientific groups based on the interaction of DNA with negatively charged nanoparticles, which have renewed the interest indirect SERS-based strategies of detection of DNA.[6-9] On the other hand, Alvarez-Puebla and co-workers developed a successful alternative strategy based on the use of positively-charged silver colloids coated with spermine molecules ([emailprotected]).[10, 11] DNA is the carrier of all genetic information in living organisms. Although it is a stable macromolecule, can be subjected to changes such as mutations derived from evolution, genetic diseases or genomic aberrations which can lead to cancer.[12] Apart from the known four canonical bases contained in DNA and RNA, a variety of modified nucleobases play a major role in gene regulation.[13] In higher organisms, epigenetic information for gen regulation is needed in order to determine their functions and properties. 5-methylcytosine is the most investigated modification in mammalian genomic DNA. However, many cytosine variants in DNA regulartory network such 5-formylcytosine, 5-carboxylcytosine and 5-hydroxymethylcytosine have been recently identified. In fact, 5-hydroxymethylcytosine is produced in mammalian tissues and depleted in human cancer cells.[14] These discoveries have suggested that new nucleotide variants possess epigenetic functions for gen regulation that have been underesti mated. In addition to epigenetic modifications, an ample variety of nucleobase lesions (such as alkylation, oxidation, deamination, and cross-linking) can take place as a result of carcinogen attacks to DNA.[15, 16] In some cases, carcinogens are inherently reactive toward DNA while others require to be firstly metabolically activated to electrophilic intermediates such as phagocyte-generated reactive oxygen, nitrogen and halogen species.[17-19] Anyhow, all these DNA lesions are mutagenic or cytotoxic and, if not properly repaired by the corresponding enzymatic systems, may induce base mispairing during DNA replication.[16] Accumulation of such mutations in genes controlling cell growth, proliferation, programmed cell death, and cell differentiation is likely to cause cancer.[20, 21] Reactive oxygen species (ROS) are possibly the main class of DNA damaging agents, which generates a wide set of different oxidative lesions [22] such as those produced by the direct attack of the highly reactiv e hydroxyl radical (†¢OH) to the nucleobase double bonds. On the other hand, inflammation-induced formation of 5-halocytosines adducts (5-chlorocytosine and 5-bromocytosine), have been identified in DNA from human tissues.[23-27] Importantly, 5-halocytosines could act as fraudulent epigenetic signals, in part explaining the link between chronic inflammation and cancer.[28-33] Due to the recent discoveries of new nucleotide variants with epigenetic functions, an intense research has been directed toward the development of novel methods to detect, profile, and sequence these base modifications in the genome and transcriptome.[34] These strategies span from pure detection and quantification methods (thin layer chromatography (TLC) analysis,[35] antibody-based detection,[36, 37] 32P-postlabelling[15] and liquid chromatography (LC)-mass spectrometry (MS)[38]) to genome-wide profiling methods and single-base-resolution sequencing methods.[39] A relatively new field in this exciting area is the screening of DNA samples for unknown or unanticipated lesions, which is referred to as â€Å"adductomics†.[40] Nowadays, this sort of analysis is primarily performed with liquid chromatography coupled with high-resolution/accurate mass spectrometry (LC−MSn).[15, 40] This technique relies on the fragmentation of protonated modified nucleobases which are then d ifferentiated according to their molecular mass.[15, 40] However, DNA adduct analysis by mass spectrometry is costly and time-consuming since it requires a prior sample preparation which normally involves several standard steps, such as DNA hydrolysis into the corresponding monomers, enrichment of the DNA adducts, removal of unmodified nucleobases and addition of an appropriate internal standard.[40] Extreme caution must be paid to avoid artificial generation of DNA lesions during these processing steps. This research project aims the direct SERS detection of four different cytosine variants in single-stranded DNA sequences, by means of [emailprotected] colloids. 5-methylcytosine (mC) and 5-hydroxymethylcytosine (hmC) were investigated due to their epigenetic importance in mammalian DNA. 5-bromocytosine (BrC) and 5-hydroxycytosine (hC) were studied as a representative modification involved in DNA damage. Transition from Raman to SERS The Raman phenomenon is related to the process where inelastic scattered photons are simultaneously emitted upon monochromatic light interaction with a specific molecule (Figure 1a). During the scattering process, a large majority of the photons are scattered at the same incident energy (Raighley scattering), whereas a small part of photons either gain or loose energy (anti-Stokes and Stokes Raman scattering respectively).[41] The resulting Raman spectral bands correspond to vibrational and rotational transitions which are specific to each molecular system providing a vibrational â€Å"fingerprint†. Raman scattering is a weak phenomenon since nearly 1 in 106 1010photons are inelastically scattered[42]. In most of the Raman studies the fraction of the spectrum involving anti-Stokes bands is usually ignored due to the weakness of the bands (Figure 1b). Although the invention of the laser in 1960s implied great improvements in Raman spectroscopy, the lack of sensitivity was stil l a sever limitation. In 1974, Fleischmann et al.[43] observed for the first time an unexpected dramatic enhancement of the Raman signal from pyridine in presence of rough silver electrodes. Later in 1977, a series of independent reports of Jeanmaire et al.[44], and Albrecht et al.[45] explained the origin of such enhancement, which renewed the interest in Raman techniques and paved the way to Surface Enhanced Raman scattering. There are two widely accepted theories that explain the origin of SERS enhancement compared to Raman scattering (Figure 1c): the electromagnetic enhancement (EM) and the chemical enhancement (CE). The EM is considered to be the major contribution of the enhancement and is highly influenced by the characteristics of the metal (composition, shape, size). This EM effect arises upon light interaction with a noble metal surface, generating collective oscillations of conduction electrons named as surface plasmon resonances (LSPRs). The coupling of these LSPRs with the emission of the analyte adsorbed or in close vicinity to the metal surface is responsible for the scattering intensification, which can reach values up to 1010-1011 [41]. In particular, large local electromagnetic fields are observed at the inter-particle junctions (known as â€Å"hot spots†) of noble metal nanoparticles which are in close proximity (mostly Ag and Au). Among others, the EM enhancement drastically decre ases as the distance between the analyte and the metal surface increases [42] which explains the requirement of close proximity between the nanostructured surface and the target molecule. The CE contribution to the SERS signal enhancement is usually weaker and, differently to the EM mechanism, is molecule-specific. In fact, when the analyte adsorbs onto the metallic substrate, a new surface-complex is formed and, new electronic transitions may be possible due to the change in the analyte properties such as the Raman polarizability. These transitions are comparable to the Resonant Raman transitions, which analogously lead to higher Raman cross sections. If both mechanisms (EM and CE) are present, their effect is assumed to be multiplicative[46]. Figure 1.(a) Schematic comparison between Raman and SERS effects (b) Raman and SERS spectra of Rhodamine G (c) SERS enhancement mechanisms***. 1.2 SERS substrates For SERS applications, noble metals substrates (mostly silver and gold) must contain features in the nano-range scale (not higher than the excitation wavelength). In fact, whereas large nanostructures highly hamper the LSPRs, too small nanostructures cannot support these plasmon resonances, leading to low enhancement factors [41]. During the past years great efforts have been made to coherently engineer SERS substrates. Two main approaches have been used for the design of SERS substrates: top down approaches, involving mainly lithographic techniques, and bottom up approaches.[47] Top down approaches allow the controlled manipulation of interparticle gaps and relatively simple functionalization of metal surfaces. In the case of bottom up approaches, nanoparticles are chemically synthetized and subsequently assembled in suspension or in ordered manner. In this context, silver and gold nanoparticles are the most used SERS-active substrates due to their outstanding optical response. Noteworthy, the LSPRs of silver substrates cover a wider wavelength range (comprising most of the visible and nearinfrared spectral region) than gold substrates. Below 600 nm, gold nanoparticles mostly absorb the incident light, hampering the surface plasmon resonances in this spectral range. [48] On the other hand, gold nanoparticles are more stable under oxidative conditions, easily prepared and with high potential tunable plasmon properties. [49] 1.3 SERS instrumentation Current dispersive Raman instruments are coupled with microscopes and several laser beam lines as excitation sources. The choice of the excitation wavelength (mainly from the visible to NIR) depends strictly on the application. An important factor to take into account when performing a SERS measurement, is the Raman scattering efficiency since it depends on the fourth power of the frequency[50]. Therefore, shorter wavelengths improve the Raman sensitivity although the risk of fluorescence or sample degradation also increases and has to be considered [51]. In this particular set-up and in most modern Raman spectrophotometers, the inelastically scattered light is collected at 180o geometry. In the confocal unit, the light from the laser initially passes through a pinhole aperture. This light is then delivered through the notch filters (interference filters) where it is completely reflected into the microscope and reaches the sample through the beam splitter. Then, the inelastically scattered light passes back through the same optics, a monocromator and finally reaches de CCD detector. The Rayleigh scattering is efficiently blocked by the notch filters.

Why are comics less educational than literary novels? Essay -- Educati

Why are comics less educational than literary novels? Differing from long narrative of simply text, comics have visual representation existing through the creative, yet simple messages. Through the visuals, comics expose the ethnic representations of shared collective perceptions, memories, and emotions. Maus I is a true account of the author’s father as a Holocaust survivor, Vladek Spiegelman, and his experiences as a young Jew in Aushwitz. Maus II is about Vladek Spiegelman recounting his own history to his son, Art, of his past relationships, friends, and tragic events he experienced and witnessed. As the reader delves into the relationship of the father and son, the reader begins to realize what the message his father tries to reach across and for his own knowledge only. People most often would think that the use of images would soften the realizations and accounts of events of Holocaust, but in reality the animated visuals greatly amplify the emotions and memories more. I n both Maus I and Maus II, the comic panels of drawn images of memories, which are much more horrifying and true to life, than the real photographs of that time in the Holocaust show that the visuals comprising the comic books have advantages in many aspects of ethnic representation. The use of animals in the comic amplifies the tragedy much more than using real life characters of humans. Maus recounts the history of Auschwitz through detailed drawings and mostly the same size comic panels with small sentences rather than a full novel. The use of images portrays a different emotion in the reader; the reader must do more close reading in order to compare and contrast the images to the text. Art Spiegelman uses animals instead of humans to make it more readab... ...force. To remove the symbol of swastika entirely or replace it with another symbol would completely disorient the reader. Therefore, Spiegelman uses the swastika to remind the reader that while the events may be unfamiliar, the novel is still a narrative about the devastating events of the Holocaust. In understanding Maus, the reader must take into account the fact that all works of literature are affected by the social and cultural contexts of its author. Spiegelman proves the point that â€Å"a picture is worth a million words† with his visuals through ethnic representation, which speak louder than the text, and contributes greatly for reader to engage and do close reading. In Maus, the use of frame stories in comic panels helped to establish both the personal and the historical context of ethnic representation by providing educational awareness to younger readers. Why are comics less educational than literary novels? Essay -- Educati Why are comics less educational than literary novels? Differing from long narrative of simply text, comics have visual representation existing through the creative, yet simple messages. Through the visuals, comics expose the ethnic representations of shared collective perceptions, memories, and emotions. Maus I is a true account of the author’s father as a Holocaust survivor, Vladek Spiegelman, and his experiences as a young Jew in Aushwitz. Maus II is about Vladek Spiegelman recounting his own history to his son, Art, of his past relationships, friends, and tragic events he experienced and witnessed. As the reader delves into the relationship of the father and son, the reader begins to realize what the message his father tries to reach across and for his own knowledge only. People most often would think that the use of images would soften the realizations and accounts of events of Holocaust, but in reality the animated visuals greatly amplify the emotions and memories more. I n both Maus I and Maus II, the comic panels of drawn images of memories, which are much more horrifying and true to life, than the real photographs of that time in the Holocaust show that the visuals comprising the comic books have advantages in many aspects of ethnic representation. The use of animals in the comic amplifies the tragedy much more than using real life characters of humans. Maus recounts the history of Auschwitz through detailed drawings and mostly the same size comic panels with small sentences rather than a full novel. The use of images portrays a different emotion in the reader; the reader must do more close reading in order to compare and contrast the images to the text. Art Spiegelman uses animals instead of humans to make it more readab... ...force. To remove the symbol of swastika entirely or replace it with another symbol would completely disorient the reader. Therefore, Spiegelman uses the swastika to remind the reader that while the events may be unfamiliar, the novel is still a narrative about the devastating events of the Holocaust. In understanding Maus, the reader must take into account the fact that all works of literature are affected by the social and cultural contexts of its author. Spiegelman proves the point that â€Å"a picture is worth a million words† with his visuals through ethnic representation, which speak louder than the text, and contributes greatly for reader to engage and do close reading. In Maus, the use of frame stories in comic panels helped to establish both the personal and the historical context of ethnic representation by providing educational awareness to younger readers.