Smrt Buses

Marketing CA Report 1 |No |Name ( as in IC / Passport) |IC / Passport Number |Telephone Number |Email Address | |1 |  Ker Shihan |F2880485R |98576248 |[email  protected] sim. edu. sg | SMRT Buses There are two types of environmental forces on SMRT buses, Macroenvironmental and Microenvironmental forces. For Macroenvironmental forces, the factors are Demographic, Economic, Natural, Technological, Political, Social and Cultural forces. For Microenvironmental forces, the factors are the company itself, suppliers, Marketing intermediaries, competitors, Publics and customers affect its ability to serve its customers. However, I will only be covering 2 of each Microenvironmental and Macroenvironmental forces. Introduction SMRT first started off in the year 1983, offering services such as Trains, Buses, and Taxis. From 1983 to 2003, SMRT buses were 2 different companies, namely, Trans Island Bus Services (TIBS) and SMRT. To increase competition of customers between local buses, 16 SBS services were given to TIBS (SMRT before merger). Operation of bus services in the north-east corridor was also offered to TIBS (SMRT before merger). In 1999, when TIBS (SMRT before merger) lost the offer to operate the north east line, TIBS and SMRT decided to merge to increase rails and buses synergy. SMRT then merged with TIBS in 2004. Microenvironmental Forces SMRT buses’ only has one competitor, the SBS Transit. SBS Transit monopolised the scheduled bus market share until SMRT was established in 1982. Now SBS Transit has about 265 bus services and daily ridership of over 2 million passengers, equivalent to 75% of scheduled bus market share. Compared to SMRT, with a daily ridership of over 730000 passengers, which is equivalent to 25% of scheduled bus market share. SMRT needs to observe their competitor to see what they are doing, find a way to counter their actions and then create a better competitive advantage. In doing so, SMRT can increase their scheduled bus market share and eventually monopolise the market. The other microenvironmental force affecting SMRT buses is their customers. To meet customers’ needs, passengers are constantly being observed. In the year 2010, SMRT introduced a new bus that is both elderly and wheelchair-friendly. The buses have steps that are low which allows the use of wheelchairs and at the same time enables swift and ease movement for passengers when moving to the rear of the bus. Also, the bus is quieter and vibrates lesser compared to buses used previously. This allows passengers to experience a smooth and comfortable ride when travelling long distances on buses. To create better competitive advantage over their competitors, SMRT opens feedback from passengers, wanting to know passengers’ opinions, so as to improve their bus services. Macroenvironmental Forces One of the Macroenvironmental forces affecting SMRT buses is the Social force. To make SMRT greener, the new bus as mentioned in the Microenvironmental force, are almost one ton lighter, compared to the older buses used. This improves both mileage and fuel efficiency by about 7%. This new bus has a passenger capacity of about 80 passengers and 1 passenger-in-wheelchair, which is almost the same as older buses. Also, harmful gases like Nitrous Oxide are converted to mostly Nitrogen and water vapour with the BlueTec ® SCR engine, thus making emission from the buses safer and cleaner. With all these new features, there will be lesser pollution, and thus creating a better image for SMRT. The other Macroenvironmental force affecting SMRT buses is the Economic force. Due to the recession in the year 2008, passenger’s spending power and patterns are affected. In September 2008, although in terms of percentage, the bus ridership is stable at 64%. However, the monthly bus ridership has decreased by more than 70000, from 23,788,000 passengers to 23,714,000 passengers. Even though there is a drop in passengers, SMRT is earning profits more than before the recession. Conclusion In conclusion, Microenvironmental and Macroenvironmental forces can affect a company in many ways. It may affect the company in both positive and negative ways. For example, from above, the economic force, during the recession even though there were lesser passengers, the profits earned still increased, but, if the number of passengers did not decrease, the profit will be higher. However, for the microenvironmental force, competitor, it may be a good and a bad thing. When there is competition, companies tend to improve their services to be better than each other. In a way, this creates a competitive advantage for the company who can meet more customers’ needs. References SGWiki (2011 February 26) The Year In Buses, Singapore, SGWiki (http://sgwiki. com/wiki/The_Year_in_Buses) (25/10/2011, 12:38) SBS (No Date) Bus Services, Singapore SBS (http://www. sbstransit. com. sg/transport/trpt_bus_overview. aspx) (25/10/2011, 12:41) SMRT Corporation Ltd(9 March 2010), SMRT INTRODUCES SOUTHEAST ASIA’S FIRST FULL LOW FLOOR EURO 5 BUS – PROVIDING GREATER ACCESSIBILITY FOR PASSENGERS, Singapore, SMRT Corp Ltd (http://www. mrt. com. sg/Upload/201031010315179993. pdf)( 23/10/2011, 20:38) Abhijit (2 November 2009, Monday), Six rail journeys for every 10 bus rides in Singapore, Singapore, PressRun (http://www. pressrun. net/weblog/2009/11/six-rail-journeys-for-every-10-bus-rides-in-singapore. html) (24/10/2011, 21:11) Seraphina Wee (22 October 2009), Mass Media Continues to Perform in Times of Downturn: NielsenConsumption of newspapers, te levision, cable, magazines, and radion have remained stable while the Internet saw considerable growth,

Cheerios commercial

This commercial was different than any other cheerios commercial because it involved an interracial couple and their mixed daughter. In the video, you see the little girl and her mother sitting at the table. The girl starts off by saying â€Å"mom, dad said cheerios were good for your heart is that true? † The mother replies, â€Å"Cheerios has healthy grains and it helps with cholesterol so that's heart healthy. † The little girl smirks and walks away.The next scene you see the dad sleeping on the ouch with a whole bunch of cheerios on top of his heart. This video received a lot of backlash on Youth about this interracial couple. One stereotypical thing that was portrayed was the fact that people refer to African Americans as having a lot of heart problems because of what they eat. The little girl obviously understood that and wanted her dad to be healthier by placing the cheerios on his heart. This of course was frowned upon because not all African Americans have hear t problems. Cheerios ended up banning the commercial and they then recreated a new one with the same family.The second commercial involved the dad telling the daughter that her mother was pregnant by using cheerios and in the end she says she would like a dog if she's getting a new baby brother. I feel as though the racial issues African Americans have gone through in the past still do somewhat exist. There are constantly so many stereotypes being made about African Americans. People are ignorant and they are so quick to Judge someone's culture without actually knowing anything about it. I myself am married to an African American man and our children are also mixed but he does not have heart problems nor does anybody in his family.Most categorize people by color and culture but that does not mean that we are all the same. Though slavery was overruled in 1865 and segregation ended in 1964, there are still people out there who believe in it. When people saw this commercial of the inte rracial couple, the people who don't necessarily like or believe in interracial couples also had some things to say about the video. Some of them said they would no longer eat cheerios because of knowing an interracial couple does or was even in the commercial.

Business ethics

Business ethics Essay Current Trends and Implications: Achieving Organizational Goals Using A Systems Approach ( Information Technology as a part of Your Competitive Strategy) Introduction to Seminar Welcome ladies and gentlemen, there are many of you here today from great distances and backgrounds of all sorts. I would like to start off first by thanking you for your time. New technologies everyday are radically changing existing industrys and creating new ones. This seminar focuses on these changes and understanding how they can help you achieve success or failure in the marketplace. Soon you will learn that your time here will give you great insight into current emerging and leading edge information and trends in using IS and IT as your competive strategy and advantage in growing your business. Beyond that your employees and other attendees will be addressed with the challenges and issuses of the many different aspects of how these systems can help you implement strategys to make your existing systems more efficient. There are pros and cons with these technologys and systems, as is expected and everything here is not for everyone. What you can expect is that you will find something there for you and your firm to further explore and possibly implement into operations. The seminar is set up for everyone, there is insight and much more to gain from the knowledge that we have amassed for you. Following will be how our seminar will run, summarizing and giving you a preview with how we implement the information to you and your clients. The Seminar will take place Friday and Saturday. It will be structured with breaks, your clients can choose which sections to attend, although we encourage the whole seminar, we know you and your clients may be issue specific. We highly recommend the seminar section on VoIP and RFID technology. Friday: 10:00 a.m. Meet and greet brunch, seminar attendees will be treated to a five star brunch to start the day off on a good foot. Here your clients can meet and mingle with business minds from all over the world. The experience and networking alone is wonderful. 11:00 Seminar will begin, attendees will receive seminar materials, phamplets and packets, to go along with the seminar. Also will be included is workbooks that provide material for the seminar and for practice and referecnce later. Go over schedule for the next two days. For the next three hours we will introduce the concept of the competitive advantage that is sought out by these IT and IS technologies. We will talk about VoIP, voice over Internet Protocol, how it can help streamline your business, make your intranets and networks more efficient and less costly. Show you how it can help with expansion and how it can be tailored to fit your specific needs. We will discuss the costs and implementation of different systems, showing you the competitive advantages. These are all accompanied with real world examples as you will soon see. Following that discussion well delve into the emerging world of RFID technology and the mandates that ensue them. With WalMart and the DoD have mandates for implementing use, RFID technology is emerging all over. There are two sides to the story, either way its coming and we are going to give you insight into this technology and tell you how it works, what it can do for you, and how. We will discuss the costs, trends, and opinions . Question #2 REFERENCE ARTICLES 1VoIP links global company: call center operations at seven locations are streamlined, while costs are lowered. (Voice Networks)(Alpha Thought) Communications News, Jan, 2004 http://www.findarticles.com/cf_0/m0CMN/1_41/112448830/p1/article.jhtml http://www. computerworld.com/printthis/2004/0,4814,95179,00.html 3Privacy in public http://www.findarticles.com/cf_0/m3190/33_37/108268107/p1/article.jhtml 4Businesses Worry About Long-Term Data Losses Will we access our saved data in 20 years? Sept, 1999 http://www. computerworld.com/printthis/1999/0,4814,37036,00.html 5The Coming Robot Revolution http://www.computerworld.com/printthis/2004/0,4814,94386,00.html 6 Riding Radio Waves eWEEK, May, 2004 by Larry Dignan http://www. findarticles.com/p/articles/mi_zdewk/is_200405/ai_ziff126287/print 7RFID Adventure http://www.computerworld.com/printthis/2004/0,4814,96012,00.html 8 The Coming Battle of the Titans http://www.computerworld. com/printthis/2004/0,4814,96318,00.html 9 Apparel Maker Gets Instant Feedback With Online Survey To http://computerworld.com/printthis/2004/0,4814,95814,00.html 10 Documentum Saves Big With Web Conference Software for Training http://www.computerworld.com/printthis/2004/0,4814,95820,00. html 11Personalize Your Job http://www.computerworld.com/printthis/2004/0,4814,95943,00.html 12Phishy e-mails and Web sites: Whats your responsibility? http://www.computerworld.com/printthis/2004/0,4814,95461,00. html Companies Fight Back Against Phishing Scams http://computerworld.com/printthis/2004/0,4814,96549,00.html 13Blades, Camera, Action! http://www.computerworld.com/printthis/2004/0,4814,96284,00.html 14Predictions For BIs Future http://www. computerworld.com/printthis/2004/0,4814,93940,00.html 15Never, ever agree to evergreen clauses http://www.computerworld.com/printthis/2000/0,4814,41674,00.html Acts of God .

Meter and Rhythm in the Poem Garden Of Love by William Blake Essay

Meter and Rhythm in the Poem Garden Of Love by William Blake - Essay Example At the age of 25 Blake married Catherine Boucher, and in 1785 he opened a print shop that failed and left him to eke out a miserable living with inadequate numbers of orders for designs and engravings. During the Napoleonic Wars not many people in England could afford the high cost of contracting the work of an engraver. In 1804 Blake was charged with sedition but was acquitted, because a drunk had wrongly accused him. In 1809 his single art exhibition of sixteen works went unnoticed by everyone except a lone critic who criticized it fiercely. Blake's literary work was so highly influenced by the politics of his time that it most likely hurt his success as an engraver. In the last years of his life, Blake met a group of young artists whose appreciation for his work eased his growing destitution. William Blake died on August 12, 1827.2 The poem is found in the anthology Songs of Innocence and of Experience. William Blake was so little recognized in his lifetime that the author only managed to write and sell his poetry intermittently over his professional career, and his poetic work was essentially little known or regarded by his contemporaries. Blake at first only wrote poetry in his spare time. Though Blake acquired some repute as an engraver and an artist, those who recognized his genius still commonly believed him to be somewhat eccentric in his own time.4 The Garden of Love, speaks fr... etime that the author only managed to write and sell his poetry intermittently over his professional career, and his poetic work was essentially little known or regarded by his contemporaries. Blake at first only wrote poetry in his spare time. Though Blake acquired some repute as an engraver and an artist, those who recognized his genius still commonly believed him to be somewhat eccentric in his own time.4 The Garden of Love, speaks from a first person viewpoint to set the individual's early experience of the spiritual loveliness of the natural world in stilted contrast with the intrusion of the unforgiving man-made constructs of religious observance. The narrator returns to the lost innocence of childhood, once experienced in its natural ambience, to revive the uplifting memory of the long-forgotten bliss of a Garden sanctuary, only to find it pointlessly spoiled by a man-made Chapel - metaphorically representing the imposition of the censorious rules and strictures of an adult religious life - overwhelming the once-healthy lighthearted and carefree ambience of his youth.5 The carefully chosen imagery of the garden and youth characterize the early experience of creation in its pristine state as the natural ambience for the exuberant child in the unaffected transparency and original innocence reminiscent of the Biblical Garden of Eden.6 The incursion of the Chapel erected in the midst of the Garden, which the narrator "never had seen" as a youth, imposes the unnatural structure of organized religion whose detrimental influence begins to escalate as the poem communicates more of its closed and censorious nature in the following stanzas. The inert stone edifice of the Chapel supplanting the promise and freedom of the green - a conventional metonymy for promise and

Persuasive Paper Research Example | Topics and Well Written Essays - 750 words

Persuasive - Research Paper Example This initiation process that aims at propagating the achievement of the set goals describes motivation (Nelson & Quick, 2013). There exist various ways in which employees could be motivated, including fair compensation, provision of conducive working environment and use of rewards and incentives. Taking the context of a convenience store where I work as cashier together with other three, I earn a monthly salary that equals that of the other cashiers despite always serving the highest number of customers monthly. In as much as we appreciate the effort that our supervisor has put forth in taking care of our welfare including provision of medical insurance and free lunch on working days, I feel that more needs to be done to optimally motivate us to serve customers faster, especially during peak times, so as to avoid longer queues which discourage customers. Appreciating the argument by Nelson and Quick (2013) that motivation would take place through a combination of approaches in any gi ven context, it would thus be important for our supervisor to adopt additional strategies in order to make us more motivated to work faster. In this case, I propose the inclusion of rewards to top performers, monthly, quarterly or semi-annually depending on the availability of resources. Danish and Usman (2010) acknowledge rewarding employee performance as a significant stimulus in sustaining high performance. The law of effects indicates that people would tend to repeat actions that cause them to attain positive rewards. As a cashiers therefore, if the supervisor rewards my all-time high transactions, I would be motivated to maintain the high performance. This has been referred to as a complement or an external reward. However, this would call for effective appraisal of employees’ performance so as to ensure accurate evaluation of performance. This argument has not only attracted research studies but has also caused scholars to come up with theories that could explain it. In deed, Victor H. Vroom attributed this phenomenon to the expectancy theory which postulates that people would desire outcomes of performance and behavior that could be considered as rewards of behavior (Nelson & Quick, 2013). This implies that with employees being aware that their effort would be rewarded by performance and further rewards, they would put greater effort which increases productivity. Of all the motivation approaches, the study of the Pakistani context by Danish and Usman (2010) indicates that rewards have been the most preferred by employees as opposed to other approaches like operating procedures, recognition and the work. As such, it means that this would be the most effective motivation strategy for our cashiers. Similar observation has been made by Brooks (2012) who acknowledges rewards as the most preferred and thus effective strategy to motivation of employees. The reason for its preference would be the value that employees attach on such rewards which would all ow for pursuance. Successful global organizations respect this postulate and as such have adopted reward plans that match their organizational needs (Nelson & Quick, 2013). The limitation of the supervisor adopting this employee motivation strategy in the convenience store, just like in any other organization would be the argument that rewards would increase the organizational expenses. Acquisition

Gender Gap Between Male and Female Obstetrics and Gynecology Essay

Gender Gap Between Male and Female Obstetrics and Gynecology - Essay Example This gender gap is not only in Britain but in the United States as well and hence making the gender gap continue to increase (Higham and Philip 142). Male as well as female medical students all receive the same kind of training in medical colleges on gynecological and obstetrician training and are therefore competent. This, therefore, means that female patients should not be afraid to be examined by the male doctors because they may even have more experience and expertise than some of the female ob-gyns when it comes to diagnosis and even treatment (Tseng and Jon Mark 17). The lack of involvement or totally keeping male students out of this field of medicine shuts men out of women’s health issues including the issues on reproduction especially relating to contraceptive which should be a shared decision between men and women (Boulis and Jerry 154). There will also be a lack of gender equality which is being advocated for in society in all careers and also there will be a lack of future role models in the society. Higham, Jenny, and Philip, Steer. â€Å"Gender gap in undergraduate experience and performance in obstetrics and gynecology: analysis of clinical experience logs.†

The Pay Model Essay Example | Topics and Well Written Essays - 750 words

The Pay Model - Essay Example Compare your ideas with someone with more experience, someone from another country, someone from another field of study. The Compensation is something that is paid to cover the opportunity cost. For example, if an employee makes commitment to work for the organization for the next five years it means he is ready to sacrifice his five years for one organization. These five years could be spent somewhere else in less time consuming and less hectic job. Therefore, the company must pay him the reasonable amount that can cover his cost of losing other jobs. The Most convincing definition from an employee’s perspective is the return. The return to employee covers both the entitlement, as well as, reward. The person who is more experienced has different perceptions regarding the definition of compensation. The compensation may be defined as risk of loss, whereas for a fresh employee the appetite for risk is high (Coppleman, 2004). Most of the developed countries may not need to think about the basic needs to cover in the compensation package but in developing countries, employee’s perception for the compensation may be totally different; the fulfillment of the basic needs may also be incorporated in the compensation package (Coppleman, 2004). Different fields require different level of compensation packages from the companies. For example, if the job requires frequent travelling, so the compensation may cover traveling, as well as, accommodation expenses, whereas if the job is totally desk based the compensation may be salary along with other perks (Coppleman, 2004). 3. What is the "network of returns" that your school offers your instructor? What returns do you believe make a difference in teaching effectiveness? What "returns" would you change or add to increase the teaching effectiveness? Network of returns refers to the fact that all bonuses, allowances and salary

WEEK 1 APPLICATION 1 Essay Example | Topics and Well Written Essays - 500 words

WEEK 1 APPLICATION 1 - Essay Example they have put in place necessary tools to enable distribution of knowledge, For instance, by putting various incentives and performance management programs, human resource department believe that workers are motivated enough to share knowledge. Other department follow suit by putting measures to either collect data or encourage workers to form occupational communities to distribute knowledge. The assumption that workers can willingly share their hard-won knowledge because of the above motivators is not true. An interview with 43 knowledge workers revealed that intrinsic motivators like job insecurity, altruistic sharing, social ties, and professionalism make workers share their knowledge. In addition, enlightened self-interest and performance reviews are extrinsic motivators to sharing of knowledge. At times, workers fail to share genuine knowledge with their colleagues because of job insecurity, to protect one’s competitive edge, personal traits, confidentiality, and lack of sharing culture. Additionally, acceptance of knowledge motivates workers to share it. The age of the persons sharing knowledge is an important motivator

Learned Helplessness Term Paper Example | Topics and Well Written Essays - 500 words

Learned Helplessness - Term Paper Example The study also revealed that four components of ORS are very much related to LH namely: role ambiguity, role expectation conflict, role isolation and self-role distance. These components are caused by unclear structures, lack of job description, specification and analysis, improper placement, inadequate communication, overlapping role expectations and lack of team effort. The results also showed that the higher the LH, the higher the ORS and vice versa. From the findings of the study, it was determined that the role of the human resource management is crucial in adopting changes to reduce the stress and LH of employees in NGOs. Some of these steps include an improvement of the communication system to clearly define the vision and mission of the organization, introduction of a framework for remuneration and a restructuring of the organization to clearly identify roles of each employee (Sha & Pethe, 2004). According to the study, if management is able to implement the suggested changes , they can reduce the stress and LH of the employees and eventually increase their morale and motivation. Learned Helplessness in Sport by Harry Prapavessis & Albert V.

Korean Creation Myth Essay Example for Free

Korean Creation Myth Essay Much as the African myth explaining the creation of its society included a talking mountain god who once lived on earth (Parrinder, African Mythology) does my own myth, based on Korean culture, explain the foundation of one society peopled with characters of strength and fortitude. Long before earth was populated, Panther and Mouse lived in a cave high over a verdant valley in the region of Mount T`aebaeksan on the border between Manchuria and what is now North Korea. There was water flowing in the streams and sun shining on the trees and grass but this was not enough for Panther and Mouse. Although they spent their time playing games and singing songs, they were lonely for additional company. The God of All and Ruler of Heaven Huan-an had a son, Huan-gun, who was also discontent with his own life confined to the heavens. He yearned to live on Earth amongst the valleys and the mountains. Huan-an agreed to honor his son’s wishes based on the requirement that he produce a population of humans worthy of this great gift who would live in the beautiful, mountainous countryside of Mount T’aebaeksan in happiness. Panther and Mouse watched from their cave as Huan-gun arrived with his heavenly ministers who created clouds, rain, and wind to keep the valley below green and lush. â€Å"I want to live down there,† said Mouse one day, scampering to the edge of his cave and watching Huan-ang’s work with great fascination. â€Å"and become human. † â€Å"Then let us go down the mountain and talk to the god,† suggested Panther. Huan-gun watched the two approach. The panther descended the mountain warily, watching where he placed his paws while the mouse scampered happily in and out amongst the boulders and trees. They crossed the stream with Mouse hanging on to Panther’s back and stood before Huan- gun to plead their case. â€Å"To become humans you must first eat only the herbs in this bag. † Huan- gun handed the animals a leather satchel. â€Å"And you must return to your cave, staying out of the sunlight and rain, for one hundred days straight. † For the next fortnight, Huan- gun observed the progress of the animals. He thought that surely Panther would be strong and fearless and triumph over Mouse to win the challenge he had presented. But after only 50 days, Panther emerged from the cave, blinking his big black eyes in the sun. â€Å"I cannot do it,† Panther declared. Huan-gun sent him back to the forest. After 100 days, Mouse came out of the cave. As sunlight touched Mouse’s body, it was transformed into that of a beautiful woman with long black hair and soft brown eyes. Huan-gun was pleased. Mouse had proved to be strong and possessed of great fortitude. He took the woman’s hand and together they lived in the valley. Huan-gun and his mortal wife produced many children and ruled the land with great compassion. Huan-gun taught his sons and daughters to live within the laws of the land and a strict moral code. From their mother they learned to sing and make up games and to call upon their inner strength. When the civilization was well and truly established, Huan-gun took his wife and became god of the mountain, where he could continue to oversee his Earth. From high in the Heavens, Huan-an looked down at the handiwork of his son and he was pleased. Works Cited Parrinder, Geoffrey. African Mythology. New York: Hamlyn Publishing Group, Ltd. , 196

Technology of Ultrasound Scans

Technology of Ultrasound Scans 2.1 Ultrasound 2.1.1 Physics of Ultrasound Sound is a mechanical wave that travels through an elastic medium. Ultrasound (US) is sound at a frequency beyond 20 000 Hz, the limit of human hearing. Bats orientate themselves with the help of US waves at 100 000 Hz. Ultrasound at frequencies of 200 000 Hz is used for navigation. The frequency range of diagnostic US is between 1 and 20 MHz. When sound encounters a boundary between two media of different densities some of the sound bounces back as an echo, a phenomenon called reflection. The rest of the sound continues through the medium but is deflected from its original path, this is called refraction. Acoustic impedance is the resistance of a medium to the propagation of sound and decides how much sound will be reflected at the interface between the media. Some of the energy of the sound is converted by friction into heat when propagating, this loss of energy is called absorption. When ultrasound waves encounter a surface, a small part of their energy is scattered away in random directions while most of the sound continues to propagate, a phenomenon called scatter. Reflection, refraction, impedance, absorption and scatter are all phenomena important for image formation in diagnostic ultrasound use. Artifacts, echoes that do not correspond to an anatomic structure but result from the physical properties of ultrasound propagation in the tissues, are also important to be aware of when using ultrasound. This phenomenon can also be of diagnostic help. One example is the acoustic shadowing of a gallstone, caused by total absorption of the sound by the stone. Diagnostic ultrasound is based on the pulse-echo principle. The smallest functional units of the transducer are the piezoelectric crystals. The crystals are embedded in the probe, and each crystal has a specific frequency. A pulse is initiated from each crystal in the probe and a longitudinal sound wave propagates through the body. Some of the energy is absorbed in the tissue and some is reflected. The reflected energy is received by the probe, which calculates the depth of the interface by measuring the time taken to return. We can say that the human body is composed of three basic materials differing in acoustic impedance: gas with a very low impedance, bone with a very high impedance and soft tissue with an impedance somewhere in between. The large mismatch between air and bone and tissue (â€Å"impedance mismatch†) causes 100% of the sound to be reflected at air/tissue interfaces and almost all the sound at bone/tissue interfaces. There is a small mismatch between different soft tissues in impedance, a fact that is the basis for diagnostic ultrasound. Different frequencies of ultrasound are used for different diagnostic examinations. Higher US frequencies (7-16 MHz) have higher resolution but are strongly absorbed by soft tissue and are therefore used for superficial structures. Very high frequencies (16- 20 MHz) will only travel for a few millimeters within tissue and are limited to intravascular and ocular examinations. Lower frequencies (3-7 MHz) are used for deeper structures, being less strongly absorbed and of lower resolution. There are different modes of displaying the amplitude of reflected sound waves: A- mode, M-mode and B-mode. A-mode (amplitude) calculates only the depth of the interface and is mainly of historical interest. M-mode (motion) is used to display moving structures and is used in cardiac ultrasound. B-mode (brightness) is the routine US image for most surgical applications. Here the returning echoes are displayed as shades of grey with the echo amplitudes represented by a grey level ranging from black to white. The individual image lines are stored, assessed and assembled on the monitor to create a two-dimensional B-mode image. Doppler ultrasound uses the Doppler effect. When US is reflected from a moving structure (i.e. blood) the frequencies of the waves change and the amount of frequency change is determined by the speed and direction of blood flow. The use of Doppler is obvious in vascular US but is also of use in other areas of diagnostic ultrasound. 2.1.2 History of Ultrasound Scientists, including Aristoteles, Leonardo da Vinci, Galileo Galilei, Sir Isaac Newton and Leonard Euler, have been studying the phenomena of acoustics, echoes and sound waves for many centuries. It was though not until 1877 that John William Strutt, also known as Lord Rayleigh, published a description of sound as a mathematical equation in â€Å"The theory of sound† which became the foundation for the science of ultrasound. Some years later, 1880, Jaques and Pierre Curie discovered the piezo-electric effect; that an electric potential is generated when mechanical pressure is applied to a quartz crystal, an important discovery that eventually led to the development of the modern- day ultrasound transducer which contains piezoelectric crystals. The first study of the application of ultrasound as a medical diagnostic tool was published by the Austrian brothers Karl and Friedrich Dussik in 1942. They attempted to locate brain tumours and the cerebral ventricles by measuring ultrasound transmission through the skull and concluded that if imaging of the ventricles was possible, the interior of the human body could also be visualized using ultrasound. Unfortunately it was later determined by Guttner, in 1952, that the images produced by the Dussiks were variations in bone thickness. Nevertheless, their scientific work marked the beginning of diagnostic ultrasonography in the medical field and Dussik wrote in an article a decade later: †As knife and forceps in surgery, the chemical agent in chemotherapy, the high frequency electric field in diathermy and X-ray application, so has medicine taken on a new physical tool in the last decade: the ultrasonic field†. George Dà ¶ring Ludwig, working together with Francis Struther, was the first scientist to visualize gallstones, implanted in the muscles and gallbladders of dogs, with ultrasound. His studies also resulted in the finding that the mean velocity of ultrasound in soft tissue is 1540 m/sec, a discovery that was to prove very important for future research. Much of his work was however considered restricted information, because he was employed by the military, and therefore not published in medical journals. John Julian Wild and Douglass Howry were also important pioneers in the ultrasound field. Wild was a surgeon who was able to visualize bowel wall thickness with ultrasound, and he also discovered a difference in echogenicity between benign and malignant tissue. Wild also developed transrectal and transvaginal transducers and a scanning device for screening patients for breast cancer. Howry built the first B- mode scanner in 1949 and, together with the two engineers Bliss and Posanky, he also developed the first linear contact scanner. The somascope, the first circumferential scanner, built in 1954, was also developed by Howry. The problem with these scanners was that the patient had to be immobilized and immersed for a long time. In the period 1957-58 an ultrasound scanner was developed by Howry and his colleagues where the patient was strapped to the plastic window of a semicircular pan filled with saline solution. Although not immersed, the patient had still to be immobilized for a long time. Finally, in the early 1960s, Howry developed the first hand-held contact scanner, together with Wright and E Myers. During the same time Ian Donald was carrying out ultrasound research in England and 1958 he published an article that came to be a landmark, (â€Å"Investigation of abdominal masses by pulsed ultrasound†), where he describes how ultrasound changed the treatment of a woman diagnosed with advanced gastric cancer dramatically by diagnosing a cystic mass with ultrasound; the mass was later resected and found to be a benign ovarian cyst. Donald contributed significantly to the field of obstetric and gynecological ultrasound for example by discovering the urinary bladder to be a natural acoustic window for the pelvic organs and by measuring the biparietal diameter of the fetus for the first time. A century earlier the Doppler effect had been discovered by the famous Austrian scientist Christian Andreas Doppler and presented in 1842 in a paper called ÃÅ"ber das farbige Licht der Doppelsterne und einiger anderer Gestirne des Himmels (On the colored light of the double stars and certain other stars of the heavens). In Lund, Sweden, the principal pioneers of echocardiography Inge Edler and Carl Hellmuth Hertz, developed the first echocardiogram in October 195323 . Subsequently Hertz and Ã…sberg invented the first two-dimensional real-time cardiac imaging machine 1967 and Edler and Lindstrà ¶m registred the first simultaneous M-mode and intracardiac Doppler blood flow recordings at about the same time. Ultrasound has in the last decades developed quickly and the first digital scanners were released onto the market in 1976, providing better and reproducible images. Interventional ultrasonography dates back to 1969 when Kratochwill proposed the use of ultrasound for percutaneous drainage. Regarding ultrasound for trauma the first report of the method for evaluating blunt trauma was dated 1971, by Kristenson in Germany. The development is still going on and in the light of advances in technology leading to smaller available machines combined with the prices of machines decreasing rapidly speculations have been made about the possibility that doctors in the future will routinely be equipped with their own ultrasound stethoscope for use in their daily clinical work. 2.1.3 Ultrasound Instruments It is important to have a basic knowledge in which an ultrasound image is produced. The components of scanner include Transmitter: Emits electrical impulses that strike the transducer piezoelectric crystals and cause them to vibrate thus producing ultrasound wave. Transducer: Transducer is one which converts one form of energy to another. In ultrasound it converts electric energy to mechanical energy and viceversa. It converts the electrical energy provided by the transmitter to the acoustic pulses directed into the patient. It serves as the receiver of reflected echoes, converting weak pressure changes into electric signals for processing. Receiver: When returning echoes strike the transducer face,minute voltages are produced across the piezoelectric elements. The receiver detects and amplifies these weak signals and provides a means for compensating for the differences in echo strength which result from attenuation by different tissue thickness by control of time depth compensation. Another important function of receiver is the compression of the wide range of amplitudes returning to the transducer into a range that can be displayed to the user. Scan Processor: Processor detects and amplifies the back scattered energy and manipulates the reflected signals for display. Control Console Display: Display presents the ultrasound image or data in a form suitable for analysis and interpretation. Over the years imaging has evolved from simple A mode display to high resolution real time gray scale imaging. Recording Device: Interpretation of images and archival storage of images may be in the form of transparencies printed on film by optical or laser cameras and printers, videotape or through use of digital picture archiving and communications system (PACS). Increasingly digital storage is being used for archiving of ultrasound images. 2.1.4 Transabdominal Ultrasound, Use and Limitations Transabdominal ultrasound of the female pelvis has been the conventional approach in imaging of the female pelvis. With this approach) a full urinary bladder is required to provide a window for imaging and to displace bowel gas. Transabdominal scanning (TAS) therefore required deeper penetration and a lower frequency transducer, usually 3 -5 MHz, must be used. The resolution of images is limited by the relatively lower frequency transducer that is required, and it also has great limitations in the obese lady, especially in the elderly who often cannot hold a full bladder. In the study of uterine hemodynamics in patients who are pregnant, these disadvantages may not be very significant, because the uterine arterial signal from these patients are usually strong. However, in the non-pregnant state, especially in postmenopausal ladies, studies of uterine hemodynamics with TAS could be very difficult. 2.1.5 Transvaginal Ultrasound, Advantages and Disadvantages Widespread availability of ultrasound imaging in the past two decades has dramatically changed the practice of obstetrics and gynecology. These specialists rely heavily upon this technology to make major decisions about management of their patients. Transabdominal sonography (TAS) images the pelvic organs through the anterior abdominal wall in the supra-pubic region. A distended urinary bladder is essential to displace the bowel loops and to provide an acoustic window. There are two major limitations of TAS. First is the need to use lower frequencies for imaging due to the longer distance between the transducer and the pelvic organs. Other disadvantage is the beam degrading effect of the anterior abdominal wall especially in obese patients. Both these limitations lead to degradation in image quality. To overcome these limitations of TAS special transducers, which could be introduced in the vagina, were designed in 1985. The vaginal approach reduces the distance between the probe and the pelvic structures allowing the use of higher frequencies. Trans-vaginal sonography (TVS) produces greatly improved resolution as compared to TAS, primarily due to the higher frequencies employed and also due to the absence of beam deformation by the anterior abdominal wall, Major advantages of TVS over TAS are better image quality and avoidance of patient discomfort due to full urinary bladder. Comparison of TVS and TAS is given in Table 2.1. 2.1.5.1 Indications of TVS TVS is indicated whenever a better look at the pelvic structures is required. Common indications include the following Early pregnancy Lower uterine segment in late pregnancy Ectopic pregnancy Pelvic masses Retroverted or retroflexed uterus Obese or gaseous patient Emergency cases when bladder is empty Follicle monitoring Oocyte retrieval Endometrial study to assess suitability in IVF ET techniques Cervical canal mucous Doppler examination of pelvic organs Interventional procedures The list is not exhaustive and newer indications are continuously being added. TVSTAS Full bladder Not essential Essential Probe frequency 5-7.5 MHz 3-5 MHz Resolution Very high Moderate Field of view Small Large ContraindicationsVirgins, Vaginal obstruction Premature rupture of membraneNone interventional uses Many usesLimited role Table 2.1 Comparison of TAS and TVS 2.1.5.2 Scan Technique Once the probe and the patient have been prepared, the transducer is gradually inserted while monitoring the ultrasound image. The urinary bladders normally consistent position in the pelvis relative to much more variable position of the uterus and the ovaries makes it a good landmark to use when making initial assessment of the transducer orientation. Three basic scanning manoeuvres of the probe are useful to scan the pelvic organs comprehensively: Sagittal imaging with side to side movements, 90 ° rotation to obtain semi-coronal images with angulation of probe in vertical plane, Variation in the depth of probe insertion to bring different parts within field of view/focal zone. A pelvic survey should be done first to ascertain quickly the relative position of the uterus and ovaries as well as to identify any obvious masses. This is obtained by slowly sweeping the beam in a sagittal plane from the midline to the lateral pelvic side walls followed by turning the probe 90 degrees into corona plane and sweeping the beam from cervix to the fundus. In multi-frequency probes proper selection is important for best results. Setting of appropriate focus in electronic arrays is equally important. In mechanical sector fixed focus probes the organ of interest is brought in the focal zone by changing the depth of insertion of the probe. Proper selection of frame averaging is also important. It should be low for fast moving structures like foetal heart and high for studying solid immobile tissues. For Doppler studies a steady probe position is essential and it helps if the examiners forearm is well supported. 2.1.5.3 Dynamic uses of the TVS probe The ultrasonographic examination can be enhanced by placing a hand over the lower abdomen to bring pelvic structures within the field of view/focal range of the probe. Localisation of the point of maximal tenderness by the probe will help in identifying the cause of pain. Dense pelvic adhesions can be diagnosed by the sliding organ sign. In the absence of adhesions, the organs move freely past each other and the pelvic wall in response to pressure by the TVS probe tip. Absence of this free movement may suggest pelvic adhesions. 2.1.5.4 Interventional uses of TVS There are many interventional uses of transvaginal sonography. Newer indications are constantly being added to the list. Some of the more common ones are given below:- aspiration of ova for in vitro fertilisation (IVF) aspiration of ovarian cyst drainage of pelvic collection multi-foetal pregnancy reduction non-surgical etopic pregnancy management early amniocentesis chorion villous sampling transvaginal embryo transfer sonohysterosalpingigraphy 2.1.5.5 Limitation of TVS It should be remembered that TVS provides a more limited field of view than TAS. A survey trans-abdominal scan usually be performed prior to the TVS to rule out the possibility of overlooking a mass lying outside the field of view of the TVS transducer. To avoid the need of a full bladder it has been suggested that a TVS examination may be followed by a TAS scan with bladder empty. The rationale behind this approach is that a mass lying outside the field of view of the TVS probe will be sufficient in size to be seen trans-abdominally even if the bladder is empty. The advent of the transvaginal sonography in 1985 has had a tremendous impact on the practice of obstetrics and gynaecology. The pelvic organs can now be imaged with a resolution not possible earlier. The management of infertility due to female factors depends mainly on the TVS. Addition of Colour Doppler to TVS now gives added information about the vascular supply of various pelvic organs. Details of foetal anatomy that can be depicted by TVS are far superior to that shown by TAS. As a new technique TVS has proved very useful and has a bright future.