Physics of the Heart

Physics of the Heart Electrocardiography Electrocardiography is the recording of the electrical of the heart by a non-invasive procedure. This is possible because the body is an electrical conductor, the ECG machine acts as a voltmeter and voltage time characteristics are measured by attaching electrodes to the patient`s skin. Electrical impulses created by the conducting tissue of the heart are picked up. The Sino Atrial Node (a small area of heart that triggers muscle contraction, acting as a pacemaker) is located at the top of the right atrium and sends a wave of electrical activity down the right atrium. Another wave of electrical activity is sent by the Atrioventricular node down the Bundle of His once the electrical activity by the SAN is received. There is a small delay before the AVN sends a wave of electrical activity, this is to allow the atria to empty fully before the ventricles contract. The ECG machine detects and amplifies electrical impulses (waves of depolarisation) initiated by the SAN. Each of the heart muscle cells in the body have a negative charge (at rest); this is called the membrane potential. The muscle cells have a negative charge because an active transport mechanism in the cell membrane maintains an excess of cations on the outside, and an excess of anions inside. This means there is a potential difference across the membrane. In the heart it is typically about 70 mV for atrial cells and 90 mV for ventricular cells. Decreasing the negative charge towards zero, via the flooding of cations (Na+ and Ca2+) into the cell, is called ‘depolarisation’ which ultimately causes the cell to contract. A healthy heart will have a distinctive wave of depolarisation that is: initiated by the SAN, spreads out through the atria, reaches the atrioventricular node and spreads all over the ventricles. The potential difference due to the heart`s electrical activity is measured by two electrodes (one positive and one negative). If the electrical impulse travels towards the positive electrode the result is a positive deflection. If the impulse travels way from the positive electrode the result is a negative deflection. Electrodes are typically placed on the arms, left leg and one or more over the heart. This helps to minimise signals from other muscle cells in the body. This can help a cardiologist to understand what is happening in different parts of the heart. The electrical impulses are translated into a waveform. The resulting ECG trace has a distinctive shape with sections that are labelled P, Q, R, S and T. Abnormalities in the shape of the wave are used to identify heart problems such as irregular contractions of the heart. The heart has a zero potential difference across it, the contraction of the atria produces a P wave (The PQ interval represents the delay to allow the ventricles to fill). The contraction of the ventricles then produces the QRS complex. Finally the T wave shows the relaxation of the ventricles. The period (R-R interval) is the time between adjacent peaks in the ECG trace. In a healthy person this varies by up to 10% between each heart beat. Heart rate is determined by averaging over multiple heart beats (Heart rate = 1/average period). The heart rate in beats per minute is equal to the frequency in hertz (Hz) x 60. The Physics of the Artificial Heart In artificial hearts (such as the one made by AbioCor), the electronic kit is implanted in the abdomen of the person receiving the transplant to monitor and regulate the pumping of the artificial electronic heart. Power is supplied from an external battery pack to components inside the patient, without penetrating the skin, using inductive electromagnetic coupling. A principal similar to this is used by transformers in the national grid. The internal battery can provide up to 40 minutes of power when disconnected from the external battery pack, for when the patient may want to have a shower for example. In transformers, an electrical current passes through a wire wound around a core, called the primary coil. Another wire is wound around the same core, this is called the secondary coil. If the two coils have the same number of turns around the core, it allows the primary coil to pass an exact copy of its electrical current to the secondary coil. These types of transformers are normally called ‘isolation transformers’. This allow two circuits to be electrically coupled, without the two circuits actually coming into direct physical contact. The image on the left shows a typical isolation transformer but the one used in this case is considerably smaller in size. The patient is constantly moving so it is quite difficult to keep the two coils aligned. This is important because the correct level of energy needs to be transferred via the wireless energy transfer system so that there is no excess transferred as heat to the surrounding tissue of the patient`s body; this could cause serious damage. Also the components need to be small enough to be carried around without too much discomfort. Furthermore, the artificial heart needs to be able to monitor the flow of blood to maintain its pumping action and make sure the correct amount of blood is being pumped. The rate of the pumping of the blood needs to be altered when the patient requires more or less oxygen, for example more oxygen is required during higher rates of respiration. Blood-flow monitors make use of ultrasound; ultrasound is used because the flow of blood can be monitored without having to be in contact with it. High-frequency sound waves are reflected off red blood cells coming out of the heart. The volume and speed of the blood can be measured using similar principles to those behind radar. The movement of these red blood cells, either towards or away from the transmitted waves, results in a frequency shift (due to the Doppler Effect) that can be measured. This data can help the system to determine the speed and direction of blood flow in the heart. Bibliography http://en.wikipedia.org/wiki/Electrocardiography http://www.iop.org/education/teacher/resources/teaching-medical-physics/electrocardiograms/page_56316.html http://www.thh.nhs.uk/documents/_departments/undergraduates/year3/ecg.pdf http://faraday.physics.utoronto.ca/IYearLab/EKG.pdf https://uk.answers.yahoo.com/question/index?qid=20090924041312AAJIBOM http://www.iop.org/resources/topic/archive/heart/ http://www.wisegeek.com/what-is-inductive-coupling.htm http://www.iop.org/resources/topic/archive/no-fly/index.html http://science.howstuffworks.com/innovation/everyday-innovations/artificial-heart1.htm http://science.howstuffworks.com/science-vs-myth/everyday-myths/doppler-effect3.htm Steve Parker (2009).The Concise Human Body Book. London: Dorling Kindersley Limited. p154-155. Adam Hart-Davis (Editor-in-Chief) (2009).Science, The Definitive Visual Guide. London: Dorling Kindersley Limited. p406-407, p448. Word Count (excluding Bibliography and Headings): 991

Role Model

Dr. Martin Luther King Jr Dr Martin Luther King Jr is my role model because he dedicated his life to helping the civil rights movement. He’s someone that I look up to because of his strong will power perseverance, and determination. Dr King’s worldview was to have equal rights and opportunities for all people despite what their nationality was. I share the same worldview as Dr King in regards to equal rights and standing for what you believe in. Dr King wanted to world to evolve in its way of thinking because he saw firsthand how African Americans were being treated.Dr King is my role model because he fought to change my history. Dr King didn’t only want to see a change happen for his self and others but also for his family. He had a wife Coretta and four children; these were the people who he wanted to see change happen for the most. After King’s death is family wanted to keep his legacy alive because they knew he stood for a good cause. According to the article A king family tribute â€Å"Family and friends remember Dr. King as a role model and dedicate themselves to his mission. Watkins, Dr.King's niece, has assembled their writings and excerpts from their speeches. All pay tribute to his spirit, abiding faith and dedication to the cause of civil rights, and they affirm their own commitment to â€Å"following the path he walked,† as his nephew, Derek B. King, states. King's father's remarks are excerpted from his autobiography. Dr King is my personal role model because is stood for what he believed in. Dr king helped shape my worldview because through his hard work he’s shown me that nothing worth fighting for comes easy.I think a lot of people look over the fact that Dr King wasn’t just trying to change the race problem it stood of many different social issues. In the article Martin Luther King Jr conception of freedom and radical democracy the author states that â€Å"king came to believe that the civil ri ghts struggle needed to expand beyond just racial desegregation in this country, He began to raise his voice against racism militarism, and economic exploitation around the world†. This is another reason why I look up to him because he didn’t only focus on one hing that needed to be changed so saw the importance of these issues and wanted to change them. Dr. king had a career as a pastor which is why I feel he never gave up believing in what he thought was right. The article Martin Luther King cover story gives background on his life â€Å"King was a preacher who spoke in biblical cadences ideally suited to leading a stride toward freedom that found its inspiration in the Old Testament story of the Israelites and the New Testament gospel of Jesus Christ.Being a minister not only put King in touch with the spirit of the black masses but also gave him a base within the black church, then and now the strongest and most independent of black institutions†. Like Dr Kin g I believe that everyone should have the right to freedom and equal rights ; However, I don’t know if I could have endured the things that Dr king had to. Once Dr King was thrown in jail because of his protest, I think if I knew I could go to jail because I was protesting I wouldn’t protest.On the other Dr King who have pathed the way for me to be able to use my freedom of speech. I would want to be brave and stand for what I believe in for myself and my family just as King did. Reference MARTIN LUTHER KING JR. A King Family Tribute. (2012). Kirkus Reviews, 80(24), 222. Orosco, J. M. (2001). Martin Luther King, Jr. ’s Conception of Freedom and Radical Democracy. Journal Of Social Philosophy, 32(4), 386-401. White, J. E. (1998). Martin Luther King. (Cover story). Time, 151(14), 160.

The Start of Essay Samples to Apply to Scholarships

The Start of Essay Samples to Apply to Scholarships In truth, it would be better to say I know there are several worthy candidates for this scholarship, but than to say I've suffered a lot more than Show respect in whatever you write. A good way to find scholarship opportunities abroad is by going to the government website of a country at which you want to study. Yes, getting additional education is frequently a necessity to compete in the modern job marketplace. Many students need to do this to cover their education and it is going to be well worth it in the very long run, but you always wish to start looking into all the totally free money options you have first. In the debut, you can begin from the start, middle, or end of your story. There aren't any parameters to follow. You will need to bear in mind that you shouldn't undervalue the significance of a strong introduction, particularly when it concerns the opening line. 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Considering all the knowledge areas and tips that you're a lready mindful of in writing a scholarship letter, you're able to easily put together all of the information that you should make sure you and your scholarship letter will stick out. With all these sites and so many discussion websites to offer information, an individual can very swiftly determine the scholarship programs he or she is able to apply for. Scholarship essays have turned into an effective tool within this search. To win, you must write a brief essay about the Seventh Amendment and the way it influences your life. On the flip side, only interest can't suffice as aptitude is imperative to be in a position to succeed in an area. Professionalism in any field needs a significant investment of time and energy. With their assistance, you can properly lean when to empathize your abilities and talents on the essay together with your achievements. 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Gender of Italian Nouns - Genere del Nome

In Italian, the gender of a noun can be maschile (masculine) or femminile (feminine). Regarding people and animals, the distinction is in relation to sex; nouns of male living beings are masculine: padre (father), scrittore (writer), infermiere (nurse), gatto (cat), leone (lion), while nouns of female living beings are feminine: madre (mother), scrittrice (writer), infermiera (nurse), gatta (cat), leonessa (lioness). However, there is not always a correspondence between grammar gender and natural gender. There are, in fact, several nouns of the type that, while considered feminine in grammatical gender, denote men: la guardia (guard), la vedetta (sentry), la sentinella (sentry), la recluta (recruit), la spia (spy). Conversely, there are other nouns that refer to women, even though they are grammatically considered the male gender: il soprano, il mezzosoprano, il contralto. In these instances, the agreement of words that refer to the noun should take into account the grammatical gender: La guardia à ¨ svelta.The guard is quick. La sentinella à ¨ attenta.The sentinel is attentive. Il soprano à ¨ bravo. (not bravo)The soprano is good. Le reclute sono arrivate. (not arrivati).The recruits arrived. For the nouns of things (both concrete and abstract) the distinction between genere maschile or genere femminile is purely conventional; only with use over time have words such as abito, fiume, and clima been assigned the masculine gender, while others such as cenere, sedia, crisi have been established as feminine. Masculine or Feminine? Besides experience and consulting the dictionary, there are two elements that can help determine the gender of a noun: the significance and the ending of the word. According to the meaning, the following are masculine: The names of trees: labete (fir), larancio (orange), il melo (apple), il pino (pine), il pioppo (poplar), lulivo (olive); but there are also those that are feminine: la palma (palm), la quercia (oak), la vite (grapevine); The names of metals and chemical elements: loro (gold), largento (silver), il ferro (iron), il rame (copper), il bronzo (bronze), lossigeno (oxygen), lidrogeno (hydrogen), luranio (uranium); The names of the months and days of the week (except Sunday): lafoso agosto (muggy August), il freddo dicembre (cold December), il lunedà ¬ (Monday), il sabato (Saturday); The names of mountains, seas, rivers, and lakes: il Cervino (the Matterhorn), lEtna (Mount Etna), lEverest (Mount Everest), i Pirenei (the Pyrenees), lAtlantico (the Atlantic), il Tirreno (the Tyrrhenian Sea), il Po (the Po), il Tevere (the Tiber), il Tamigi (the Thames), il Danubio (the Danube), il Garda, il Trasimeno. But many names of mountains are feminine: la Maiella, le Alpi (the Alps), le Dolomiti (the Dolomites), le Ande (the Andes); as well as many names of rivers: La Senna (the Seine), la Loira (the Loire), la Garonna (the Garonne); The names of the cardinal points: il Nord (il Settentrione), il Sud (il Mezzogiorno, il Meridione), lEst (il Levante, lOriente), lOvest (il Ponente, lOccidente). According to the meaning, the following are feminine: The name of fruit: la ciliegia (cherry), la mela (apple), la pera (pear), lalbicocca (apricot), la pesca (peach), la banana (banana). What is remarkable, however, is the number of fruits that are considered masculine: il limone (lemon), il dattero (date), il fico (fig), lananas (pineapple); The names of the sciences and in general abstract notions: la matematica (mathematics), la chimica (chemistry), la biologia (biology), la linguistica (linguistics), la bontà   (goodness), la giustizia (justice), la fede (faith), la pace (peace); The names of continents, states, regions, cities, and islands: lEuropa (Europe), lAfrica (Africa); lItalia (Italy), la Francia (France), la Spagna (Spain), lIndia (India), lArgentina (Argentina); la Toscana, la Calabria, lUmbria, le Marche; la dotta Bologna, la Napoli degli Angioini; la Sicilia, la Sardegna, la Groenlandia (Greenland), le Antille (West Indies). But there are also many names considered masculine, including those of states and regions: il Belgio (Belgium), il Perà ¹ (Peru), lEgitto (Egypt), gli Stati Uniti (United States): il Piemonte, il Lazio; and those of cities and islands: il Cairo, il Madagascar. Depending on the ending, the following are masculine: Nouns ending in -o: il libro, il prezzo, il quadro, il vaso, il muro. There are not many instances in which nouns ending in -o are feminine: la mano, la radio, la dinamo, la moto, lauto, la foto, la virago, la biro. By convention eco in the singular is feminine (uneco, una forte eco), but frequently is considered masculine as well; in the plural it is always regarded as masculine (gli echi) Nouns ending in a consonant, mainly of foreign origin: lo sport, il bar, il gas, il tram, il film; but there are also foreign words ending in a consonant that are feminine: la gang, la holding. The following are feminine: Nouns ending in -a: la casa, la sedia, la penna, la terra, la pianta. However, many are masculine. Apart from nouns ending in -a that apply to both genders (such as il giornalista / la giornalista), various nouns derived from Greek are masculine, such as those that end in -ma: il poema, il teorema, il problema, il diploma, il dramma; and others such as il vaglia, il pigiama, il nulla; Nouns ending in -i: la crisi, lanalisi, la tesi, la diagnosi, loasi. But brindisi is masculine; Nouns ending in -tà   and in -tà ¹: la bontà  , la civiltà  , la verità  , lausterità  , la virtà ¹, la gioventà ¹, la servità ¹. Nouns ending in -e, unless they belong to certain classes of suffixes (-zione, -tore, -ite), can be either gender: il ponte, lamore, il fiume, il dente; la mente, la fame, la notte, la chiave.