Managerial economics Essay Example for Free

Managerial economics Essay 1. If a firm raises its price for Product X, TR will increase. Uncertain, Total revenue = Price Ãâ€" Quantity Sold. The price elasticity of demand tells us there are two eï ¬â‚¬ects, first is price eï ¬â‚¬ect. If price increase, each unit sold sells for a higher price, which tends to raise revenue. Second is quantity eï ¬â‚¬ect. If price increase, fewer units are sold, which tends to lower revenue. This is determines by which price eï ¬â‚¬ect or the quantity eï ¬â‚¬ect is stronger 2. When MR MC, MP (marginal profit) will be positive.  True, for each unit sold, marginal profit equals marginal revenue (MR) minus marginal cost (MC). Then, if MR is greater than MC at some level of output, marginal profit is positive and thus a greater quantity should be produced. 3. If a 10% increase in price leads to a 5% increase in TR, demand must be elastic. False, if an increase in price causes an increase in total revenue, then demand can be said to be inelastic, since the increase in price does not have a large impact on quantity demanded. 4. If the cross price elasticity is positive for two goods X and Y, X and Y must be complements. False, if the goods are complements, the value will be negative because quantity demanded increases when the price of complement falls. Example, if the price of petrol decreases to RM2 a litre, sales of cars would increase. 5. Maximizing TR is never a desirable goal for a firm.  True, profit is the difference between a firms total revenue and its total opportunity cost. Total revenue is the amount of income earned by selling products. But it does not include the total opportunity costs of all inputs into the production process. Hence, it is never a desirable goal for a firm. Firm should consider maximizing Profit instead of TR. 6. The more inelastic the demand, the more likely it is that a firm can have regular price increases. True, if firm have regular increase in price (refer to Appendix 1) from P4 to P5, the decrease in the quantity demanded is relatively small (from Q4 to Q5). It means that, the more inelastic the  demand, the percentage change in quantity demanded is less than percentage change price. Hence, firm can have regular price increases. 7. If EP = -1.25 for Group A, and EP = -.375 for Group B, and a firm uses price discrimination, Group A should pay a higher price than Group B. False, Group A is elastic and Group B is inelastic. The consumers in the inelastic sub-market will be charged the higher price, and those in the elastic sub market will be charged the lower price. So Group B should pay higher price. Please refer to Appendix 2 for illustration. 8. A consumer spends 1% of her income on Good A and 25% on Good B. Price Elasticity of Demand should be greater for Good B. True, if the consumer spends less of her income, means that Good A is a necessity good and spends more of her income means that Good B is a luxury good. Luxuries tend to more elastic than necessities as there are more options for consumer. 9. Income elasticity for an inferior good is always negative. True, because quantity demand falls as income rises. Quantity demanded and income move opposite directions, inferior goods have negative elasticity. 10. The more inelastic the demand, the flatter the demand curve. False, inelastic demand have steeper curve because quantity demanded does not respond strongly to price changes. Please refer to Appendix 3 for illustration. For a inelastic demand product such as cigarettes, when price increase by 10%, the quantity demanded will fall by 3.8%. 11. If demand goes from P = 1850 .05Q to P = 1700 .05Q, Demand has increased. False. If P = 1850 .05Q then Qd= 37000-20P and if P = 1700 .05Q, then Qd= 34000-20P. The demand curve shift to left and hence, the demand decreases. Please refer to Appendix 4 for illustration 12. If TC goes from TC = 1250 + .5Q to TC = 1200 + .6Q, FC have gone up and VC have gone down. False, because TC=TFC+TVC. From the equation above shows that, the FC decreases leads TFC to fall from 1250 to 1200 and the VC increases leads TVC to gone up from 0.5 to 0.6. Part B (Explain in a short Essay (not more than 1 page each)) 1) Define demand, discuss various determinants of demand. Demand is the quantities of good or service that consumers are willing to buy at various prices within some given period of time. Holding all other factors constant, the price of a good or service increases as its demand increases and vice versa. When factors other than price changes, demand  curve will shift. There are 5 determinants of the demand curve. First factor is price of related goods. A good or service can be related to another by being a substitute or complement. If price of a substitute changes, we expect the demand for the good under consideration to change in the same direction as the change in the substitute’s price. For instance, if the price of coffee rises, the demand for tea should increase. The complement goods are the goods that can be used together. Price of complement and demand for the other good are negatively related. Example, if the price of sugar increases, the demand for coffee will fall. Second factor is income, as people’s income rises, it is reasonable to expect their demand for a good to increase and vice versa, the demand curve will shift right. A fall in income will lead to a decrease in demand for normal goods. Goods whose demand varies inversely with income are called inferior goods. Third determinant is future expectation. If enough, buyers expect the price of a good rises in future, the current demand will increase. Also, if consumers’ current demand will increase, they expect higher future income. For example, in 2005 housing prices rose, but people bought more because they expected the price to continue to go up. This drove prices even further, until the bubble burst in 2006 (Stafffullcoll.edu. n.d.). Forth factor is tastes and preferences. This is the desire, emotion, or preference for a good or service. If consumer preference is favorable change will leads to an increase in demand. Likewise, unfavorable change leads to a decrease in demand. Example, companies spend thousands on advertising to make you feel strongly that you want a product. Last determinant is number of buyer. If the number of buyers in market rises, the demand increases. For example, the housing bubble case. Low-cost mortgages increased the number of people who were told they could afford a house. The number of buyers actually increased, driving up the demand for housing. When they found they really couldnt afford the mortgage, especially when housing prices started to fall, they foreclosed. This reduced the number of buyers, and demand also fell. 2) Briefly explain the concept of Law of diminishing returns? Discuss its assumption and importance? The law of diminishing marginal returns means that the productivity of a variable input declines as more is used  in short-run production, holding one or more inputs fixed. This law has a direct behavior on market supply, the supply price, and the law of supply. The main reasons the marginal product (MP) of this variable input declines is the fixed input. The fixed input imposes a capacity constraint on short-run production. For example, in a sandwich production, the size of the sandwich-producing kitchen and equipment is fixed. The company employs additional workers, the kitchen becomes increasingly crowded. Only so many workers can use the sandwich-preparation counter to prepare sandwich. While adding additional workers do increase total sandwich production, the extra production attributable to these workers is certain to fall as the capacity of the fixed input is limited. In fact, adding too many workers actually results in a negative marginal product, hence, total product falls. The law of diminishing marginal returns is reflected in the shapes and slopes of the total product, marginal product, and average product curves. The most important of these being the negative slope of the marginal product curve. Appendix 5 shows the graph three product curves. The total product (TP) curve shows that the total number of Sandwich Company produced per hour for a given amount of labor. The increasingly flatter slope of the TP is attributable to the law of diminishing marginal returns. Also, the marginal product curve indicates how the total production of Sandwich Company changes when an extra worker is hired. The negatively-sloped portion of the MP curve is a direct embodiment of the law of diminishing marginal returns. Further, the average product curve indicates the average number of Sandwich Company produced by workers. The negatively-sloped portion of the AP curve is indirectly caused by the law of diminishing marginal returns. As marginal product declines, due to the law of diminishing marginal returns, it also causes a decrease in average product. 3) Explain the various economies and diseconomies of scale? Economies of scale are the cost advantages that a business can exploit by expanding the scale of production. The effect is to reduce the long run average (unit) costs of production. Economies of scale have brought down the unit costs of production and feeding through to lower prices for consumers (appendix 6). It could be achieved by buying new machinery, and build a bigger factory. There are two types of economy of scale and depending on the particular characteristics of an industry, some are more important than others. Firstly, internal economies of scale are a  product of how efficient a firm is at producing, that is specific to individual firm. Example, advantages are enjoyed by expansion. Next, external economies of scale occur outside of a firm but within an industry. Example, industry’s scope of operations expand due to better transportation network, will result a decrease in cost for a company working within industry, , external economies of scale have been achieved. Diseconomies of scale are the forces that cause larger firms to produce goods and services at increased per unit costs. The concept is the opposite of economies of scale to a situation which economies of scale no longer function for a firm. Rather than experiencing continued decreasing costs per increase in output, firms see an increase in marginal cost when output is increased (appendix 6). When a firm expands its production scale beyond a certain level, it suffers certain disadvantages. These disadvantages are called internal diseconomies of scale. The result of these diseconomies of scale is a fall run average cost. There are a number of factors that might give rise to inefficiencies as the size of the firm grows. As the size of the firm grows beyond a certain level, organization, control and planning is needed. This makes the managerial responsibilities more difficult. Delegation of the management functions to lower personnel becomes very common. Since the lower personnel lack the adequate experience to undertake the task, it may result in low output at higher cost. All these lead to an increase in the long-run average cost. Further, the external diseconomies of scale are beyond the control of a company increases its total costs, as output in the rest of the industry increases. The increase in costs can be associated with market prices increasing for some or all of the factors of production. For instance, high competition for labor, when there is more firms in industry, there will be increased demand for labor, making the best workers harder to keep (Keat and Young, 2009). References Stafffullcoll.edu. n.d. DETERMINANTS OF DEMAND. [online] Available at: http://staffwww.fullcoll.edu/fchan/macro/1determinants_of_demand.htm [Accessed: 28 Mar 2014]. Keat, P.G. and Young, P.K.Y., 2009 ‘Managerial Economics: 6th ed. Economic Tools for Today’s Decision Makers’. Pg. 266-268

Causes of The Great Depression Essay -- essays research papers

The Great Depression It is said that the cause of the catastrophic stock market crash known as the great depression was due mostly to uncontrolled political and industrial systems otherwise known as capitalism. However, the timeline leading up to the Great Depression proves that many other factors played a role in the stock market crash that occurred in the decade of the 1930's. So lets take a look at rather four, factors contributing to the great depression that we will further discuss in the following paragraphs. Four of the main causes that led up to the great depression were unequal distribution of wealth, uncontrolled political and industrial systems, high tariffs and war debts. Money was distributed mostly between the rich and the middle-class, in the United States, and between the U.S. and Europe. This imbalance of wealth created an unstable economy this type of the economy eventually lead up to large market crashes. These market crashes, caused the American economy to be overturned. The total income in the United States rose from $74.3 billion in 1923 to $89 billion in 1929 this rise in the economy was due to the Coolidge Prosperity(Business and Industry was flourishing and big business became bigger so the stock market went up greatly) even after this boost in the stock market the money wasn’t making its way around equally because most farmers were still poor. United States maintained high 1. tariffs on goods imported from other countries, at the same time that it was making foreign loans and trying to export products. This combination could not be sustained: If other nations could not sell their goods in the United States, they could not make enough money to buy American products or repay American loan... ... June 1939 7.2 10.4 + 7.9 17.2 1940 6.9 9.9 1941 7.7 12.1 1942 10.3 24.8 1943 13.7 44.8 1944 21.7 45.3 1945 21.3 43.7 As you can see, Roosevelt began to bring the people out of the depression and that resulted in some astonishing growth numbers. (Roosevelt's average growth of 5.2 percent during the Great Depression is even higher than Reagan's 3.7 percent growth during his Seven Fat Years ) When 1936 saw a phenomenal record of 14 percent growth, Roosevelt eased back on the deficit spending, overly worried about balancing the budget. Between 1940 and 1945, the Growth Deficit Product nearly doubled in size, from $832 billion to $1,559 billion in constant 87 dollars. And this occurred as deficit spending soared, to levels Keynes had earlier and unsuccessfully recommended to Roosevelt

A comparison between cardiac CT scanning and cardiac digital subtraction angiography (DSA)

Abstract Coronary artery disease affects nearly one tenth of the UK population and remains the leading cause of death in the western world. To investigate and provide interventions for coronary artery disease, imaging of the coronary arteries to enable visualisation of atheromatous plaque is required. This review looked at the techniques of cardiac computed tomography scanning and cardiac digital subtraction angiography, and their contribution to the investigation of coronary artery disease. Comparison of the procedures considered technique, radiation exposure, contrast agent, clinical indications and efficacy in diagnosis of coronary artery stenosis. On comparison of the effectiveness of the techniques, both were shown to have been effective non-invasive procedures that may be used to rule out diagnoses and avoid inappropriate use of invasive angiography. The research shows mixed evidence for cardiac computed tomography angiography as a test of high specificity, however sensitivity and speci ficity of cardiac digital subtraction angiography is high, and therefore suggest that the techniques may be useful in low risk patients. Introduction Coronary artery disease remains the main cause of death in the UK and western world (Hacker, 2013; Liu et al., 2002) and contributes a substantial disease burden, affecting 7% of men and 5% of women in the UK in 1999 (Liu et al., 2002). Coronary artery disease results from the build up of atherosclerotic plaque within the arteries supplying the myocardium. This plaque limits the flow of blood through the arteries, and can cause ischaemia of the heart muscle. If the plaque becomes unstable and ruptures, this may lead to thrombus formation and the complete occlusion of an artery, resulting in a myocardial infarction (McClure et al., 2009). Acute coronary syndrome (ACS) is a sub-classification of coronary artery disease and encompasses unstable angina, non-ST elevation myocardial infarction and ST elevation myocardial infarction. ACS represents a range of conditions that result from thrombus formation in coronary arteries, and if untreated has poor prognosis and high mortality (NICE, 2010). To investigate and provide information for interventions for coronary artery disease and ACS, visualization of the coronary arteries and any lesions caused by atherosclerotic plaque is required. Advances in technology have given rise to several sophisticated perfusion analysis techniques, which provide greater prognostic value than morphological imaging (Hacker, 2013). Perfusion analysis allows the blood flow through the coronary vessels to be observed and any abnormalities in the perfusion can be interpreted as a functional consequence of atherosclerotic changes within the vessels (Hacker, 2013). Currently, UK guidelines (NICE, 2010a) recommend coronary angiogram as first line management for patients presenting with ACS. This enables imaging of the coronary arteries to assess perfusion. It is important to assess the circulation as arteries can be affected from the earliest stages of endothelial dysfunction to high-grade coronary artery stenoses (Hacker et al., 2010; Bugiardini et al. 2004; Kaufmann et al., 2000), and this provides the information necessary for prognosis and intervention. With the advances in technology, there are now various diagnostic tests available to assess coronary artery disease, including coronary angiography and computed tomography (CT) scanning (Gorenoi, Schonermark & Hagen, 2012). This review aims to review the literature on coronary CT scanning and digital subtraction angiography, their clinical applications, techniques and comparative value in coronary artery assessment and diagnosis. Cardiac Digital subtraction angiography Coronary angiography is the conventional diagnostic procedure used in coronary artery disease. It is a minimally invasive technique, whereby a catheter is placed into the radial or femoral artery and is advanced through the arterial system to the coronary arteries. A contrast agent is then injected at the aortic root and allows visualization of the arteries using x-ray in real time at up to 30 frames per second. This allows a view of the extent, location and severity of coronary obstructive lesions such as atherosclerosis and enables prognostic indication (Miller et al., 2008). Coronary angiography also enables catheter placement either side of the lesion to assess pressure changes and determines the degree of flow obstruction (Miller et al., 2008). . Digital subtraction angiography (DSA) again works by introducing a contrast agent into the coronary arteries and taking x-rays in real time, however a pre image is taken by x-ray. This allows for the post images to be subtracted from the original mask image, eliminating bone and soft tissue images, which would otherwise overlie the artery under study (Hasegawa, 1987). Unlike conventional angiography, it is possible to conduct DSA via the venous system, through accessing the superior vena cava via the basillic vein (Myerowitz, 1982). This removes the risks associated with arterial cannulation (Mancini & Higgins, 1985). The procedure can also be performed with a lower dose of contrast agent and be done more quickly therefore eliminating constraints of using too much contrast during a procedure (Myerowitz, 1982). Whilst DSA is the gold standard in arterial imaging of carotid artery stenosis (Herzig et al., 2004), the application of DSA to the coronary arteries is limited due to motion artefacts associated with each heartbeat and respiration (Yamamoto et al., 2009). There are numerous cardiac clinical applications of DSA, it can be used to assess coronary blood flow (Molloi et al., 1996), valvular regurgitation (Booth, Nissen & DeMaria, 1985), cardiac phase (Katritsis et al., 1988), congenital heart shunts (Myerowitz, Swanson, & Turnipseed, 1985), coronary bypass grafts and percutaneous coronary intervention outcomes (Katritsis et al, 1988; Guthaner, Wexler & Bradley, 1985). However, others have suggested that the coronary arteries are not visualized well due to their small size, movement, their position overlying the opacified aorta and left ventricle, and confusion with other structures such as the pulmonary veins (Myerowitz, 1982). Cardiac CT Scanning Development of CT scanning in the 1990s enabled an increase in temporal resolution that was sufficient to view the beating heart, and they now provide a non-invasive technique for diagnostic and prognostic purposes. Cardiac CT scans have clinical applications that go beyond perfusion investigation, and can be used to assess structure and function of the heart (for example in electrophysiology disorders or congenital heart disease) due to its ability to provide anatomical detail (Achenbach & Raggi, 2010). CT scans can be used to assess coronary artery disease with and without injection of contrast agent (Achenbach & Raggi, 2010) by calcium scan or CT angiography. Coronary calcium CT scanning uses the evidence base that coronary artery calcium is a correlate of atherosclerosis (Burke et al., 2003) and is a strong prognostic predictor of the future development of coronary artery disease and cardiac events (Arad et al., 2000; Budoff et al., 2009; Achenbach & Raggi, 2010). Calcium is easily depicted on CT scan due to its high CT attenuation, and is classified according to the Agatson score, which considers the density and area of the calcification (Hoffman, Brady & Muller, 2003). Coronary CT angiography (CTA) allows visualization of the coronary artery lumen to identify any atherosclerosis or stenosis within the vessels. Patients are injected intravenously with a contrast agent and then undergo a CT scan. There are limitations regarding the suitability of patients for coronary CTA due to prerequisites of sinus rhythm, low heart rate and ability to follow breath-holding commands. Additionally, obesity presents a problem for patients that cannot fit into the scanner and affects the accuracy of the procedure. (Achenbach & Raggi, 2010). Comparison of cardiac DSA and cardiac CT scanning The technical differences between cardiac DSA and cardiac CT scanning give rise to differences in the clinical indications for the procedures, their diagnostic efficacy and also different risks or relative benefits to the patients. Due to the nature of the images produced by coronary CTA and DSA, each lends itself to different indications for use. Whilst coronary DSA provides imaging of all aspects of perfusion, CTA used with contrast agent also provides this however has the additional advantage of being able to assess structure and function of the heart. Coronary CTA has been shown to have a high accuracy at detection and exclusion of coronary artery stenoses (Achenbach & Raggi, 2010). In a multicentre trial conducted by Miller et al. (2008), patients underwent coronary calcium scoring and CT angiography prior to conventional invasive coronary angiography. The diagnostic accuracy of coronary CTA at ruling out or detecting coronary stenoses of 50% was shown to have a sensitivity of 85% and a specificity of 90%. This showed that coronary CTA was particularly effective at ruling out non-significant stenoses. Additionally, coronary CTA was shown to be of equal efficacy as conventional coronary angiography at identifying the patients that subsequently went on to have revascularisation via percutaneous intervention. This was shown by an area under the curve (AUC), a measure of accuracy of 0.84 for coronary CTA and 0.82 for coronary angiography. Miller et al.’s (2008) study included a large number of patients at different study sites , and additionally represented a large variety of clinical patient characteristics. The author’s claim that these factors contribute to the strength and validity of the study findings, and suggest that in addition to using patients with clinical indications for anatomical coronary imaging, should be used as evidence that coronary CTA is accurate at identifying disease severity in coronary artery disease. Miller et al. (2008) did however,, find that positive predictive and negative predictive values of coronary CTA were 91% and 83% respectively and therefore suggested that coronary CTA should not be used in place of the more accurate conventional coronary angiography. A low positive predictive value (in relation to the prevalence of disease) was proposed to be due to a tendency to overestimate stenosis degree as well as the presence of artefacts leading to false positive interpretation (Achenbach & Raggi, 2010). Other research providing comparison between coronary CTA and conventional coronary angiogram has highlighted variability in results. A meta-analysis conducted by Gorenoi, Schonermark and Hagen (2012) investigated the diagnostic capabilities of coronary CTA and invasive coronary angiography using intracoronary pressure measurement as the reference standard. The authors found that CT coronary angiography had a greater sensitivity than invasive coronary angiography (80% vs 67%), meaning that coronary CTA was more likely to identify functionally relevant coronary artery stenoses in patients. Despite this,, specificity of coronary CTA was 67%, compared to 75% in invasive coronary angiography, meaning that the technique was less effective at correctly excluding non-diagnoses than invasive coronary angiogram. This research appears to contradict the power of cardiac CTA at excluding diagnoses of coronary artery stenosis as suggested by Miller et al. (2008), he study did combine evidence from over 44 studies to provide their results and therefore had a large statistical power. The authors interpret the results in light of the clinical relevance of cardiac imaging, suggesting that patients with a higher pretest possibility of coronary heart disease will likely require invasive coronary angiography for revascularisation indicating that coronary CTA may be a helpful technique in those patients with an intermediate pre-test probability of coronary heart disease that will therefore not require invasive angiography. Goldberg et al. (1986) investigated the efficacy of DSA in comparison to conventional coronary angiography in 77 patients. They found that the two angiograms agreed within one grade of severity in 84% of single cases and 90% of multiple cases, identifying both patent and lesioned arteries. The results led the authors to conclude that there was no significant difference between the two methods and that DSA could be used in selective coronary angiography to find results comparable to that of conventional angiography. In addition to being a small study into the efficacy of DSA, the study also had several sources of inherent variability that should be considered when interpreting the results. These included differing sizes of digital imaging screen and non-use of calipers, meaning that the interpretation of the images could vary throughout the study. The authors also suggest that whilst showing strong support for the use of DSA in coronary artery disease, the technique may not actually p ermit better prognostic determinations or clinical judgements that are better than conventional angiography, and therefore the further implementation of the techniques may not be founded or necessitated. More recently, there has been further research looking at the effectiveness of DSA as a way of measuring coronary blood flow. Whilst motion artefacts have proven a problem in lots of past research (Marinus, Buis & Benthem, 1990; Hangiandreou, 1990), recent research has developed methods to minimise these. Moilloi and colleaues (1996) showed that using a motion-immune dual-energy digital subtraction angiography, absolute volumetric coronary blood flow could be measured accurately and thus provide an indication of the severity of any arterial stenosis.This may provide further suggestion for clinical implementation of DSA. Although these studies provide evidence for the efficacy of cardiac DSA and CTA, they often make comparisons to conventional angiography. This is useful as a baseline comparison, however it is difficult to make comparisons between the two procedures directly due to less available evidence making direct comparisons. Lupon-Roses et al. (1985) conducted a study investigating both coronary CTA and venous DSA. The study looked at the efficacy of both techniques at diagnosing patency of coronary artery grafts compared to the control conventional angiography. CT was shown to diagnose 93% of the patent grafts and 67% of the occluded grafts whereas DSA correctly diagnosed 98% and 100% of patent and occluded grafts respectively. Interestingly, the DSA picked up the 11 grafts that were misdiagnosed by CTA and the CTA picked up the 2 grafts misdiagnosed by the DSA. This data may suggest that individually, DSA has a better profile for diagnosis of coronary artery occlusion, however if the two procedures are used in combination exclusion of patent arteries and diagnosis of occluded arteries would be effective (Lupon-Roses et al., 1985). Coronary DSA and CTA are both non-invasive procedures (unlike the conventional coronary angiography where a wire is placed in the coronary vasculature). With the only invasive part of the procedure being the injection of the contrast material into a vein. This presents a significant advantage to both procedures over that of conventional angiography, and may even permit investigation on an outpatient basis (Meaney et al., 1980). Similarly, both DSA and coronary CTA are favoured because of their intravenous approach, eliminating the risks of bleeding or arterial injury from an intra-arterial catheterization and being able to be used in those with limited arterial access. However, although the intravenous approach used in cardiac DSA makes it favourable, it does lead to difficulty with visualisation of the coronary arteries due to the overlying iodinated pulmonary and cardiac structures (Mancini & Higgins, 1985). Therefore,, intra-arterial DSA is also sometimes used (Yamamoto et al., 20 09). As with all CT scanning, coronary CTA carries with it a dose of ionizing radiation (Brenner & Hall, 2007). Studies have estimated that for diagnostic CT scanning, patients are on average exposed to 12mSv of radiation during the procedure, the equivalent of 600 x-rays (Hausleiter et al., 2009). Estimates of radiation doses associated with conventional coronary angiography are lower than that of coronary CTA at 7mSv (Einstein et al., 2007). Additionally, DSA technique reduces the radiation dose from that of conventional coronary angiography as the vessels are visualised more clearly (Yamamoto et al., 2008). The dangers of radiation exposure are increased risk of developing cancer, skin injuries and cateracts (Einstein et al., 2007). It is therefore important that the benefits of conducting the procedure greatly outweigh the risk of radiation exposure. CT calcium scanning provides a low radiation dose at around 1mSv (Hunold et al., 2003). Cardiac CT calcium scanning does not require administration of a contrast agent, unlike in coronary CTA and DSA that use iodine based contrast agents. The risks associated with contrast agent include nephrotoxicity and risks of hives, allergic reactions and anaphylaxis (Maddox, 2002). The amount of contrast agent used is partly dependent on the length of the procedure and how clearly the arteries can be visualised. For this reason, both cardiac CTA and DSA use less contrast agent that conventional coronary angiography (Brant-Zawadzki, et al., 1983). CT calcium scanning of the coronary arteries is therefore recommended in those with less likelihood of coronary artery disease (NICE, 2010). Both coronary CTA and DSA require interpretation by trained physicians, and the importance of training and achieving intra-rater reliability should not be underestimated (Pugliese et al., 2009). Conclusion Overall, both coronary CT and DSA have been demonstrated as effective procedures for the imaging of the coronary arteries in CAD (Achenbach & Raggi, 2010; Miller et al., 2008; Moilloi et al., 1996; Goldberg et al., 1986). Whilst cardiac CT scanning does provide a wider range of clinical applications, allowing assessment of perfusion as well as cardiac structure and function (Achenbach & Raggi, 2010), coronary DSA has many applications that allow assessment of coronary blood flow (Molloi et al., 1996; Katritsis et al, 1988; Booth, Nissen & DeMaria, 1985; Guthaner, Wexler & Bradley, 1985; Myerowitz, Swanson, & Turnipseed, 198). Both cardiac DSA and CTA procedures have their advantages. As non-invasive procedures, these techniques pose less risk to patients, and enable the possibility of outpatient investigation, to be used to rule out diagnoses and to avoid inappropriate invasive coronary angiogram (Gorenori et al., 2012). Additionally, intravenous access is preferential to arterial cannulation for the contrast infusion, removing the risks associated with bleeding or intra-arterial injury. Cardiac DSA exposes the patient to a lower dose of radiation that coronary CTA (Hausleiter et al., 2009; Yamamoto et al., 2008; Einstein et al., 2007), which is beneficial at reducing the risk of genetic mutations and cancer. Cardiac CTA and DSA also have their common disadvantages. The use of contrast agent may present side effects for the patient including kidney damage and risk of allergic reactions and anaphylaxis (Maddox, 2002). For this reason, calcium CT scanning can be useful in patients that are not at high likelihood of coronary artery disease (NICE, 2010b). Additionally, both cardiac DSA and CTA are subject to motion artefacts from respiration and heart beats, which can cause difficulties with interpretation (Achenbach & Raggi, 2010; Yamamoto et al., 2009). In the case of cardiac CTA, this excludes a subset of patients that are unable to follow commands and those who have high heart rates. Overall, cardiac CTA and cardiac DSA are effective, non-invasive imaging techniques for assessment of coronary artery disease. Whilst they are not the gold standards in cardiac monitoring, they can provide important diagnostic information without exposing patients to the risks of invasive angiography. Due to this, their use should be weighted against clinical need, the risks of the procedures, and the suitability of the patient. Interpretation of cardiac CTA and DSA imaging should be by trained individuals. 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Seguro médico para visa de inmigrante para residencia

Serà ¡ negada la visa de inmigrante para la residencia a todos los solicitantes que no puedan probar que tendrà ¡n seguro mà ©dico dentro de los 30 dà ­as siguientes a su ingreso a Estados Unidos o recursos econà ³micos suficientes para hacer frente a gastos mà ©dicos previsibles. ALERTA: decisià ³n judicial Por orden del juez Michael Simons de Oregon, esta medida sobre obligacià ³n de seguro mà ©dico està ¡ suspendida por 28 dà ­as.En la vista preliminar prevista para el 22 de noviembre se decidirà ¡ si esta suspensià ³n se extiende por todo el tiempo que dure el juicio sobre la validez de esta medida.  ¿Cuà ¡l es la base legal de esta nueva regla? Esta nueva regla ha sido establecida por proclamacià ³n ejecutiva del presidente Donald Trump, que es una medida con peso similar a una orden ejecutiva. La base legal es el Tà ­tulo 8 del Cà ³digo de Estados Unidos 1182 (f) que permite al Presidente a restringir el ingreso al paà ­s a cualquier extranjero o categorà ­a de extranjeros que puedan perjudicar a EE.UU. Es la misma ley por la que se limita la admisià ³n a EE.UU. a ciudadanos de paà ­ses como Irà ¡n, Siria, Libia o Somalia y a ciertas categorà ­as de nacionales de Venezuela o Corea del Norte.  ¿A quià ©nes afecta este nuevo requisito de seguro mà ©dico para EE.UU.? Solo aplica a los migrantes que se encuentran fuera de EE.UU. y deben obtener una visa de inmigrante para la residencia como, por ejemplo, los casos de green card por peticià ³n de un familiar, por peticià ³n de una empresa, por inversià ³n, o por haber ganado la loterà ­a de visas de la diversidad. Sin embargo, està ¡n excluidos de esa regla los nià ±os menores de 18 aà ±os que acompaà ±an a su padre o a su madre o guardià ¡n legal, los cuales sà ­ està ¡n sujetos a la nueva regla de obligatoriedad de seguro mà ©dico. Por otro lado, esta nueva regla no afecta a los migrantes ya presentes en EE.UU. que solicitan la tarjeta de residencia mediante un ajuste de estatus. Tambià ©n està ¡n excluidos de esta regla los extranjeros que obtienen la residencia por asilo, condicià ³n de refugiado o son iraquà ­es o afganos que ayudaron al Ejà ©rcito de Estados Unidos. Tampoco aplica a los extranjeros que ingresan a EE.UU. con visas temporales no inmigrantes como, por ejemplo, la de turista, inversià ³n, estudiante, intercambio, trabajo, etc. Sin embargo, aunque no es obligatorio sà ­ que es altamente recomendable que cuenten con un seguro mà ©dico que cubra cualquier problema de salud durante su estancia en Estados Unidos debido al alto costo de los servicios sanitarios.  ¿Quà © tipo de seguro mà ©dico se debe tener para obtener la aprobacià ³n de la visa de inmigrante? En la entrevista en el consulado se deberà ¡ probar que, si se obtiene la visa de inmigrante, se tendrà ¡ seguro mà ©dico en los 30 dà ­as siguientes al ingreso a EE.UU. o se tiene medios econà ³micos suficientes para hacer frente a gastos mà ©dicos. El tipo de seguro puede ser, entre otros, el suministrador por un empleador, un plan de Medicare, la inclusià ³n en un seguro familiar o un seguro mà ©dico privado comprado para el migrante. No se admiten seguros de Medicaid para migrantes de 18 aà ±o o mà ¡s. En ningà ºn caso se admiten los seguros mà ©dicos comprados utilizando subsidios pà ºblicos al amparo de Obamacare ni tampoco subsidios estatales. En cuanto a la cantidad de dinero que se considera suficiente para hacer frente a gastos mà ©dicos si no se tiene seguro, la proclamacià ³n ejecutiva de Trump no establece una cantidad fija, sino que simplemente afirma que debe ser suficiente para cubrir cualquier problema mà ©dico previsible. Serà ¡ el oficial consular quien, en cada caso, determinarà ¡ si se cumple el requisito. Sin embargo, se espera que el Departamento de Estado establezca unos parà ¡metros al respecto.  ¿Cuà ¡ndo entra en vigor esta nueva regla de seguro mà ©dico? Esta previsto el comienzo de su aplicacià ³n el 3 de noviembre de 2019 para las visas de inmigrante nuevas y tambià ©n las que està ¡n pendientes. Sin embargo, las visas de inmigrante ya aprobadas a tal fecha no se verà ¡n afectadas. Sin embargo, una orden judicial ha paralizado momentà ¡neamente esta medida y se està ¡ a la espera de una resolucià ³n definitiva. Accià ³n ejecutiva sobre seguro mà ©dico y carga pà ºblica La accià ³n ejecutiva sobre seguro mà ©dico es, en algunos aspectos, similar a la decisià ³n de la administracià ³n Trump sobre la ampliacià ³n de la carga pà ºblica como causa para negacià ³n de varias peticiones y solicitudes migratorias. Sin embargo, son diferentes y no deben confundirse. Ademà ¡s, al menos por el momento, la aplicacià ³n de la carga pà ºblica està ¡ judicialmente suspendida temporalmente. Sin embargo, el requisito sobre seguro mà ©dico comenzarà ¡ a aplicarse a partir del 3 de noviembre a menos que con antelacià ³n a esa fecha se logre su paralizacià ³n en Corte.  ¿A cuà ¡ntos inmigrantes afectarà ­a esta medida? Segà ºn estimaciones del Migration Policity Institute el 65 por ciento de los migrantes que ingresaron a EE.UU. en los aà ±os 2014 a 2016 no podrà ­an haber emigrado si se hubiera aplicado esta medida. En base a esos cà ¡lculos puede afirmarse que de aplicarse este requisito sobre seguro mà ©dico las consecuencias serà ­an enormes y afectarà ­an cada aà ±o a decenas de miles de migrantes. Puntos clave: seguro mà ©dico para visa de inmigrante  ¿Quà © es?: la visa inmigrante para la residencia serà ¡ negada si los migrantes no pueden probar que tienen recursos econà ³micos suficientes para hacer frente a gastos mà ©dicos previsibles o que tendrà ¡n seguro mà ©dico en los 30 dà ­as siguientes a su ingreso a EE.UU., si la visa es aprobada. ¿Cuà ¡l es la base legal?: proclamacià ³n ejecutiva del presidente Donald Trump en base a la ley 8 U.S.C. 1182 (f).Fecha de entrada en vigor: 3 de noviembre de 2019, a menos que una decisià ³n judicial la paralice al menos momentà ¡neamente. ¿A quià ©nes afecta?: a migrantes que necesitan la visa de inmigrante para obtener la residencia permanente. No aplica a los migrantes que la obtienen mediante un ajuste de estatus. Este es un artà ­culo informativo. No es asesorà ­a legal.