The advantages and limitations of electron microscopy.
The advantages and limitations of electron microscopy There are two main branches of microscopy that are pertinent to cell biology. These branches arise from the two types of microscope; the light microscope and the electron microscope. The basic principles of light microscopy have been known since circa 17th century, however improvements in lens manufacture in circa 19th century allowed the use of microscopy to be much more practically available and useful. This is increased ability inspired rapid research into both the design of microscopes and the preparation of specimens. However, the light microscope can only magnify objects bigger than 0.2 micrometres; due to its limited resolving powers. This is because it utilises a beam of light. Relatively, light has a long wavelength, this means that when there are two small points close together there is too much refraction and wave front overlap, the eye then only sees one point. This can also be considered in terms of objects "crossing the path" of the wavelength. The smallest wavelength of visible light is 400nm, the diameter of mitochondria is 1000nm, and therefore mitochondria cross the path of the light wave. However ribosomes have a diameter of 22nm, and do not cross the path of the light wave and are therefore not seen by the light microscope. As biologists came to realise these limitations they understood that the
investigating the relationship between the diameter and the current in a wire at its melting point
Investigation Report Aim Theory Electrical resistance is a measure of the degree to which an object opposes the passage of an electric current. The SI unit of electrical resistance is the ohm. Its reciprocal quantity is electrical conductance measured in siemens. Resistance is the property of any object or substance of resisting or opposing the flow of an electrical current. The quantity of resistance in an electric circuit determines the amount of current flowing in the circuit for any given voltage applied to the circuit. Some formulae for resistance are where R is the resistance of the object / ? V is the potential difference across the object / V I is the current passing through the object / A (Ref. http://en.wikipedia.org/wiki/Electrical_resistance) where R is the resistance/ ? ? is the resistivity / ?m l is the length of the wire / m A is the cross section area of the wire / m A = ?() = ? where A is area / m d is the diameter / m Putting the formulae together, so (Ref. http://physics.bu.edu/~duffy/PY106/Resistance.html) Aim of investigation The aim of this work is to investigate the relationship between the resistance and the diameter of the wire. Variables Variable Independent / Controlled / Dependent Resistance D Resistivity C Length of wire C Diameter I Prediction Since the theory suggests that So So the resistance should be
writing exam french healthy lifestyle
À mon opinion je suis assez en bonne santé parce que j'ai tendance à manger correctement et je fais de l'exercice souvent. La santé est très importante, parce que vous devez manger équilibré et faire un de l'activité physique pour la forme et éviter l'obésité et les autres problèmes de santé. Pour garder ma bonne forme je fais du sport régulièrement et je manger équilibré. Au petit déjeuner normalement je mange du pain et je bois du thé au lait. Á midi, je ne mange pas rien parce que à 'la cantine c'est trop cher. En revanche normalement je mange un sandwich au fromage pour mon déjeuner quand je retourné à la maison. Je ne mange jamais de porc parce que c'est interdit aux musulmans. Hier, pour le dîner j'ai mangé de l'agneau avec des légumes et j'ai bu de l'eau. J'adore les légumes, surtout les haricots verts et les petit pois. Par contre, je déteste les choux de Bruxelles. Le goût ne me plait pas du tout. C'est beaucoup trop amer pour moi. Je n'aime pas le fast-food parce qu'il y a trop de graisse et de sucre dedans mais je mange quelque fois. J'ai des petites faiblesses, par exemple j'adore le chocolat, mais en général je n'ai pas des mauvaises habitudes. Pour rester en forme, il est bon de faire de l'exercice. Je marche aussi souvent que possible. Je fais aussi du sport tous les jours. J'ai pratiqué beaucoup d'activités différentes
The purpose of this experiment is to see what factors affect the period of one complete oscillation of a simple pendulum.
SCIENCE COURSEWORK PENDULUM EXPERIMENT Aim The purpose of this experiment is to see what factors affect the period of one complete oscillation of a simple pendulum. In this investigation I am going to discover and investigate the factors, which affect the time for one complete oscillation of a simple pendulum. It is important to understand what a pendulum is. A pendulum has a weight or mass fixed and left hanging of the string. An oscillation is one cycle of the pendulums motion e.g. from position a to b and back to a. I will time how long it takes for one oscillation of the pendulum. I am going to do a simple preliminary experiment to investigate which of the factors I test have an effect on the time for one complete oscillation. The factors basic variable factors I can test are: ? Length (the distance between the point of suspension and the mass) ? Mass (the weight in g of the item suspended from the fixed point) ? Swing size (the length I release the pendulum) *The point of equilibrium is the point at which kinetic energy (KE) is the only force making the mass move and not gravitational potential energy (GPE). I will test the extremes of these factors as I can assume that if they have any effect on the period of oscillation it will become obvious. To make sure my results are accurate enough to allow for any anomalies I will repeat the experiment 2 times for each
To what extent has New Labour abandoned traditional Labour values?
To what extent has New Labour abandoned traditional Labour values? After decades of consistent defeat, the Labour party sought the need for change in the early 1980s. Although Labour started to change under the leadership of Neil Kinnock in 1983, it wasn't until 1990 that Peter Mandelson, then the party's director of communications, was able to claim that "we have now effectively completed the building of the new model party". And it wasn't until 1994 when Tony Blair was chosen to lead the Labour party that the "New Labour" project was introduced. The introduction of New Labour was aimed at getting rid of the "party of the past" image that Labour had earned to itself and also to evolve into an electable party. For this to happen, radical policy changes needed to be made. In Blair's view, "Labour needed a quantum leap to become a serious party of government again". There were however, significant constraints on the way to achieving drastic changes. An attempt to modernise the Party was in need to change policies which were formulated based on values which the party was actually based and founded upon. The changes that were proposed by Tony Blair and those who shared his views were in clear contrast with the Socialist ideology on which the Labour Party had originated from. The proposed changes also sought to prevent the Trade Unions- another main source of the Party's
Suggest and justify any changes that each of your businesses could make to enable them to meet their aims and objectives more effectively
Suggest and justify any changes that each of your businesses could make to enable them to meet their aims and objectives more effectively Manchester Airport Manchester airport is the 3rd largest airport in the UK. They are always looking for new ways in which they can achieve this. One of their main objectives is to reduce costs to airlines. They could achieve this by incorporating new leisure facilities into the airport, e.g. cinema and bowling alley. This could help them achieve the objective as they would be making profit from the new facilities and so could lower the rent prices to the airlines, this could also help because more airlines would want to set up in Manchester airport due to lower renting cost, so the airport will have more customers, however the airport would have to spend money on building/creating space to build the new facilities. This would mean that the airport would loose money until the facilities have been built and are running and are making sufficient profits. As this would mean money loss, the airport could find another way of making money as it is being built. They could charge retailer more, this would mean taking a higher percentage of the retailer's profits. This would mean the airport would make more money but the retailers would make a decrease in profits. This could also cause retailers not wanting to set up in Manchester Airport as the
Outline the clinical characteristics of one anxiety disorder
Outline the clinical characteristics of one anxiety disorder (10 Marks) Anxiety is an adaptive response, an individual with an anxiety disorder experiences anxiety that is disproportionate to threats that are presented. Phobias are the most common form of anxiety disorders. Phobias are an extreme irrational fear of certain situations, objects, people or activities; the level of fear is so great the object or situation is avoided whenever possible. Phobias are classified into three categories, specific phobia, social phobia and agoraphobia. Agoraphobia and social phobia usually interfere with the individuals' daily life, whereas specific phobia generally has less impact. Specific phobias are a fear of specific objects such as animals, the environment, a situation or blood and guts. The prevalence is 4-7% of the population. Specific phobias can be caused from direct experience, observation or from being told to fear the object. The clinical characteristic for this is for the individual with the phobia to avoid the feared object. The anxiety from the situation often results in restlessness, jumpy behaviour; in general the individual finds it difficult to relax and may experience a startled response when presented with the feared stimuli. Social phobias are due to the individual's self-consciousness of their behaviour and a fear of being negatively judged by others in social
P2: Describe the structure of the tissues of the body and their role in the functioning of two named body systems.
P2: Describe the structure of the tissues of the body and their role in the functioning of two named body systems. Epithelial tissue: Simple Epithelial tissue is one of the four major tissue types in the body, acting as an interface between the body and the rest of the world. Skin is composed of epithelial tissue which lines the body cavities and major organs. There are several different types of epithelial tissue, which form to fulfil specific needs and functions. This tissue, known collectively as the epithelium, can filter, absorb, and diffuse various substances, and it is also involved in sensory perception and bodily secretions. According to Marieb (2000) 'covering and lining epithelium covers all three body surfaces and contains versatile cells. One type forms the outer layer of skin while others dip into the body to line it cavities.' Cuboidal Cuboidal epithelium is cube-shaped with spherical nuclei in the centre that line ducts and tubes and allows materials to pass through. They are found in secretive or absorptive tissue like the exocrine gland, the lining of the kidney tubules and in the ducts of the glands. They also constitute the germinal epithelium, which produces the egg cells in the female ovary and the sperm cells in the male testes Columnar Columnar epithelium forms the lining of the stomach and intestines. Their nuclei are elongated and are
Analysis of "Seven Ages of Man" by William Shakespeare.
Seven Ages of Man By William Shakespeare. Seven Ages of man is a poem written by William Shakespeare. It's actually a speech given by one of his characters named Jacques in his play As You Like it. Jacques is a pessimistic character who the poet uses to portray the life of a man in seven different parts. The first line of the poem "All the worlds a stage is a metaphor in which the world is associated with a stage. It is also the central metaphor around which the entire poem revolves. The next few lines also use similar terminology related to theatre. The word "All" in the first line establishes universality and we are told that men everywhere go through the same phases of life. The next line "...Just like actors, men and women in this world are not free to do as they will and are directed and controlled by their destiny. And just like actors in a play, the people make their appearances and go away i.e. they are born into this world and die. Because Jacques looks more towards the negative, he mentions death as in "exit" first and then birth or "entrance". This is because he looks at life's negativities closely. And so, this man, a player who has probably made an entrance plays seven main parts in his life. These parts are referred to as acts as in the line "And one man in his time plays many parts. His act being seven ages." When the child is born, he is an infant who
Examine the contribution of functionalist explanations towards an understanding of the family
JOHN SMYTH SOCIOLOGY ESSAY (1500 words) EXAMINE THE CONTRIBUTION OF FUNCTIONALIST EXPLANATIONS TO AN UNDERSTANDING OF THE FAMILY Functionalists believe that the family is a positive institution and view the ideal modern family as being the Nuclear Family. The nuclear family is described by Giddens (1989, p385) as a family 'which consists of two adults living together in a household with their own or adopted children'. Abercrombie et al (2006 p168) defines the nuclear family as 'Social units comprising a man and a woman living together with their children' Regardless of individuals definitions of what the nuclear family is, it is perceived as a family consisting of a father, mother and their children.The functionalist view (most popular in the 1960's) of the nuclear family comprises of a breadwinner husband and dependant wife and children - the 'cereal packet family' (Leach 1968) - this view of the family is also taken by sociologists like Murdock and Parsons. Functionalists take a consensus approach towards society and believe social institutions such as a family play an important part - i.e. the family makes a positive contribution towards society. Although Murdock and Parsons put across are similar themes - they believe that a nuclear family is best suited for a healthy society. Functionalists see the family as essential to the smooth running of society, therefore they
