Group work PDF
Group work PDF
Distributed Databases
Distributed Databases
Transactions: Revisiting how domination worked in colonial Africa
ASC seminar by Florence Bernault (Sciences Po)
Babbage: Insectageddon? The insect apocalypse may not be imminent, but the decline of insect species is still a concern. And we speak to Dr Angela Gallop about her career as one of Britain’s most eminent forensic scientists. Also, when will a robot barista serve you a latte? Kenneth Cukier hosts
Lessons from Google CEO Sundar Pichai’s Congressional Testimony
Congress recently grilled Google CEO Sundar Pichai on privacy issues, political bias and possible plans to introduce a censored search engine in China. Experts from Wharton and elsewhere weigh in on his testimony.
2.4 Analysis of nucleic acids by electrophoresis and hybridisation Nucleic acids can be separated according to size by gel electrophoresis, most commonly performed using a horizontal gel (Figure 7a). This is in contrast to the vertical gel electrophoresis set-up, which is generally used for analysis of proteins. The size of DNA molecules is usually expressed in terms of the number of
1.1 Introduction to vitamins and why we need them Before the 19th century, one of the hazards of long sea voyages was a condition called scurvy, whose symptoms were loss of hair and teeth, bleeding gums, very slow healing of wounds, and eventually death. Hundreds of sailors and explorers died from scurvy until a Scottish physician, James Lind, in the 1750s discovered that adding a daily portion of citrus fruit to the rations of those at sea could prevent the condition, whereas adding cider, vinegar or various other substances that he tested,
Conclusion In this course you have found out that: The sensation of pain is caused by the release of a chemical (prostaglandin) that stimulates the nerve endings and sends an electrical message to the brain. Pain can be reduced if the formation of prostaglandin can be inhibited. Prostaglandin is formed, from arachidonic acid, in a cavity in the active site of the enzyme cyclooxygenase (COX). Geometrical isomerism can b
1.7.1 Enzymes: nature's catalysts It will probably come as no surprise to you that chemical reactions, including the conversion of arachidonic acid into prostaglandin, do not occur instantaneously and the rate at which they take place can be very variable. Some reactions are over in a flash, such as the burning of gunpowder, and others take months, such as rust formation on a car. All chemical reactions can be speeded up by increasing the temperature of the reactants. In the laboratory one often ‘cooks’ reaction mixtures
War, Intervention and Development
How can we prevent a country from returning to civil war? When and how should external parties intervene in serious conflicts? This album looks at the decade of violence and destruction that occurred in Sierra Leone in the 1990's. Now that peace has finally come about through the efforts of the international community, it's time to debate whether the root causes of war have been adequately addressed, and what lessons can be learned. 50% of Sierra Leoneans are under 15 and unskilled. Lack of edu
Appendix 2 Acronyms 5.13.1 Rectangular bar If a solid rectangular bar is excited by striking it, energy is supplied that starts the bar vibrating transversely. The bar will vibrate in a number of modes simultaneously since the striking action supplies energy over a range of frequencies. The motion of the bar will be the superposition of the standing-wave patterns of the excited modes. Assume for the moment that the rectangular bar is supported in such a way that both ends are free to vibrate and the effects of the supports can b 5.2 Vibrating string: speed of wave propagation If standing waves are set up when two travelling waves moving in opposite directions interact, then how are standing waves set up on a string and why are they set up only at certain frequencies? To help answer these questions, I want you first to imagine a length of string that is fixed at one end and held in someone's hand at the other. Suppose the person holding the string flicks their end of the string in such a way that an upward pulse is sent along the string. As the pulse pa 5.1 Standing waves You learned earlier that when a musician plays a note on an instrument, they supply it with energy that causes the primary vibrator to oscillate at certain specific frequencies. In Section 5 we are going to look at what determines these specific frequencies for some of the primary vibrators found in different instruments. In Unit TA212_1 Sound for music technology: an introduction, we talk about travelling waves: that is, waves that propagate outwards away from their sourc 4 Excitation For a player to be able to sound a musical instrument, there must be a means of inputting energy to set up the vibration. This energy may be introduced in a short, sharp burst or continuously over a period of time. In the case of brass instruments such as the trumpet and trombone, and woodwind instruments such as the flute and oboe, the player feeds in energy by blowing air into the instrument. The energy can be supplied in a short burst – in which case short-lived ‘staccato’ note 4.6 Tidal rivers and estuaries Most of the major cities and harbours in the world are located on estuaries. The estuarine ecosystem is a unique intermediate between the sea, the land and fresh water. A rather precise definition of an estuary is 'a semi-enclosed coastal body of water, which has a free connection with the open sea, and within which sea water is measurably diluted with fresh water derived from land drainage'. This excludes large bays with little or no freshwater flow, and large brackish seas and inland 3.5.5 Biological indicators A great many biological species and individuals occur in normal streams. These often differ markedly in their sensitivity to environmental factors, and likewise the tolerances of various species to different types of pollution vary considerably. The major groups of organisms that have been used as indicators of environmental pollution include bacteria, fungi, protozoa, algae, higher plants, macroinvertebrates and fish. The benthic 'bottom living' macroinvertebrates are particularly suitable a 2.7 Infiltration Entry of precipitation through the soil surface and on downwards, by gravity, is known as infiltration. The rate at which this process can take place is governed by the permeability (a measure of the ease with which water can flow through the subsurface layer) and by the existing degree of saturation of the soil. Infiltration can be impeded by outcropping impermeable rocks or by paved areas, and also by the presence of finegrained soils with a low permeability (such as clay). At certain times 3.4.5 Fretting fatigue An additional possibility was considered. It was known that there was significant movement of the bridge during passage of traffic, because users had noticed it many times when crossing. The joints would thus have been subjected to rotary motion around the pin in order to accommodate such vibrations. Could these have caused fatigue crack growth at the bearing surfaces? Contact between a circular and a flat plate creates so-called Hertzian stresses at the contact zone: compressive at the 3.3.1 Sequence of events It was important to establish the precise sequence of events leading up to and during the collapse. From which part had the collapse started? Why had so much of the structure been destroyed? Was there any prior warning of the failure? What part had the weather conditions at the time played? Eyewitnesses were plentiful, and each had a different perspective of the bridge as it fell. There were some common parts to their statements. Most of the witnesses, especially survivors from vehicles
APC angle-polished convex (connector) ASE amplified spontaneous emission ASK amplitude shift keying cw continuous wave DSF dispersion-shifted fibre DWDM dense wavelength division multiplexing EDFA erbium-doped fibr
