OpenLLM-France/wikimedia huggingface dataset:
# A-level Applied Science/Sports Science

Fitness can be achieved at various levels, making the individual feel good, which may be carrying out the exercise they enjoy, this can include a daily 10 minute walk or even football on a regular basis, as it helps to build more energy within an individual’s body. Keeping fit and healthy can reduce the risks of certain diseases, as this routine produces a great change in the lifestyle to improve levels of fitness. Fitness is also the well-being of an individual as this will involve them achieving fitness through nutrition also; this will fall under the various factors to be achieved in order to actually perform activities reaching fitness. Fitness is the term related to physical activity, it can consist of various meanings to different people, and this is because some may believe an individual should reach several goals before they can achieve fitness, whereas some may believe that fitness is the term to describe the physical activity an individual has the ability to perform.
# A-level Applied Science/Physics of Performance Effects/Lighting control systems

Light in an auditorium can be controlled by a lighting control system.
Explain:
* how light levels are controlled;
* how to produce a system to control light;
* the characteristics of an effective control system;
* analogue and digital systems.
# A-level Applied Science/Physics of Performance Effects/Sound control systems

Sound in a venue can be controlled by a sound control system.
Explain:
* how a sound system works;
* how sound can be controlled;
* the characteristics of an effective control system;
* digital and analogue systems;
* feedback and how it can be incorporated into a control system.
# A-level Applied Science/Physics of Performance Effects/Light

You need to know about:
* how light travels.
* the intensity and amplitude of light.
* the relationship between distance from a light source and intensity
* the relationship between the frequency, wavelength and colour
* the three primary colours of light, complementary colours and how they combine
* the production of a spectrum from white light
* lighting effects (silhouettes, shadows, lightning flashes, optical illusions, etc.)
* lighting aids (footlights, floodlights, stroboscopes, dimmer boards, dimmer racks, slide projectors, data projectors, colour wheels, mirror balls, lasers, etc.)
You need to measure:
* the reflection of light by plane and curved surfaces.
* the refraction of light by prisms and lenses.
* the use of colour filters
* reflection and absorption of light to colour objects
# A-level Applied Science/Synthesising Organic Compounds
## About this Unit

From the AQA Specification:
   In this unit you will learn about:
   * the wide range and number of organic compounds formed by carbon;
   * how to describe organic compounds;
   * how to recognise a range of aliphatic compounds, their functional groups, structural formula and shape;
   * recognising examples of a range of chemical reactions and writing balanced equations;
   * how to make and purify organic compounds;
   * how to determine theoretical and actual percentage yield.

## How you will be assessed

This unit is assessed through the work you complete for your portfolio.
The marking criteria are found in the AQA specification.

## What you need to know

| Organic chemicals | Organic reactions | Spectroscopy | Practical |

## References & notes

Organic chemistry: wikibook
# A-level Applied Science/Synthesising Organic Compounds/Organic reactions

Each functional group has its characteristic reactions. Synthetic chemists use their understanding of how chemical changes take place (reaction mechanisms) to devise efficient synthetic routes for the preparation of organic compounds. In order to give details of the main types of chemical reaction you should be able to recognise and give examples of various reaction types:

## Redox

Oxidation is defined as when a molecule or atom:
* Loses electrons
* Loses hydrogen atoms
* Gains oxygen atoms
(These are really the same process. Hydrogen normally exists chemically as the hydrogen ion, H$^+$. Losing a hydrogen atom is equivalent to losing a hydrogen ion and an electron. Oxygen normally exists as the oxide, O$^{−2}$. When a molecule gains an oxygen atom, it has to lose two electrons to convert oxygen to oxide.) Oxidising agents include potassium manganate (VII) (‘permanganate’, KMnO$_4$) and potassium dichromate (VI) (K$_2$Cr$_2$O$_7$). The metals in these compounds have lost many electrons (7 and 6 respectively). They oxidise other compounds to recover their own lost electrons.
Reduction is the opposite of oxidation (fill in the blanks):
Reducing agents include hydrogen itself and hydrogen-rich metallic compounds such as lithium aluminium hydride (LiAlH$_4$) and sodium borohydride (NaBH$_4$).
* Alkenes can be oxidised to alcohols
* Alcohols can be oxidised to aldehydes, ketones and carboxylic acids.
* Aldehyes can be oxidised to carboxylic acids.
* Carboxylic acids can be reduced to alcohols.

## Hydrolysis (as a substitution reaction)

The hydroxide ion (OH-) can replace the –NH$_2$ group of an amine or a primary amide. Secondary amides and esters can be split into carboxylic acids and alcohols or amines by the addition of a water molecule. This is the reverse of the condensation process that forms amides and esters. An acid or base catalyst is used. If a base catalyst is used, the salt of the carboxylic acid is obtained, not the acid itself. If an acid catalyst is used to hydrolyse an amide, the ammonium salt is generated, not the amine.

## Esterification

Esters are formed when an alcohol and a carboxylic acid react. To catalyse the reaction an acid is added. Concentrated sulphuric acid is used because it also removes the water formed and so helps drive the reaction forwards.

## Condensation polymerisation

Esterification links two molecules to form a larger one, but many more molecules can be incorporated if required. With a diol and a dicarboxylic acid, for example, we can make a polyester:
Secondary amides form from amines and carboxylic acids in the same way as esters form from alcohols and carboxylic acids:
Not surprisingly, we can make polyamides from diamines and dicarboxylic acids:
Polyamides are also made from amino acids. Proteins are polyamides. Artificial polyamides are commonly known as nylons.
These polymeric substances are useful as fibres and gears. Your notes should include balanced chemical equations for the various types of reaction. You should note the reagents that are used in the reactions.
# A-level Computing/AQA/Paper 1/Theory of computation/Halting problem
## Halting Problem

Very early on in modern computing, a British academic named Alan Turing devised the halting problem. This problem is to do with whether we can determine if a program will ever come to a halt or run for ever, for example:
Would write hello to the screen then stop. However, take a look at:
This would never finish, it would never come to a halt as x will always be larger than 8 and never get any smaller. This means the while loop will continue for ever, constantly printing out "hello". In the two cases shown it is easy to tell if a program will halt or not, but it isn't so easy for all programs. Imagine we get a more complex piece of code:
This is harder but still solvable taking a little more thinking and a little time on the processor. We could get a piece of code that takes weeks, years or even thousands of years to finish. But how can we know that all programs will end or not? To determine whether the program halts we:
* run a program with a given input, if it stops we know it stops
* BUT if it keeps running beyond a reasonable amount of time we cannot conclude that it will loop for ever (maybe we need to wait a little longer...)
Surely we create a mathematical proof to determine whether code will end or not I hear you say. Well let's prove just the opposite:
Let us create a program K that will loop forever if the result of H is to halt, and halt if the result of H is to loop for ever:
We can therefore see that there are examples of programs such as K that we cannot determine whether they are ever going to halt.
* Read more on the halting problem
# A-level Computing/AQA/Paper 1/Theory of computation/Problem-solving

1. Analysis The requirements and goals of the project must be established, and a data model created. The needs of the end user are considered, and alternative solutions to the problem may be suggested
2. Design Data structures will be specified, algorithms, user interfaces, screen designs and reports will all be designed
3. Implementation The program code is written
4. Testing The whole system must be tested for presence of errors, using selected test data covering normal, boundary and erroneous data
5. Evaluation The system is evaluated according to given criteria
Problem-solving Solving logic problems is good training for "computational thinking" - basically, the ability to think logically about a problem and apply techniques for solving it. This is closely related to the skill of designing algorithms which can be turned into computer programs.
# A-level Computing/AQA/Paper 1/Theory of computation/Regular languages
## Regular Languages

* Finite State Machines with and without Output (Mealy Machines)
* Maths for Regular Expressions
* Regular Expressions
* Regular Languages
* Backus-Naur Form for Context-Free Languages

## Regular Expressions

A regular expression is an expressions used to specify a set of strings that satisfy given conditions (A sequence of characters that define a search pattern). They are used by programmers and computers to work with text patterns. The most popular implementations are in search engines and search & replace dialogues in word processors.
Most programming languages support regular expressions, but the most common symbols are described below:
* | A vertical bar separates alternatives e.g. (D|d)is(c|k)
* ? A question mark indicates zero or one of the preceding element e.g. colou?r
* * An asterisk indicates zero or more of the preceding element e.g. aa and aabbb would match aab*
* + A plus indicates one or more of the preceding element e.g. abc and abccc would match abc+
If your programming language supports regular expressions, such as Python, the syntax might be different.
# A-level Computing/AQA/Paper 1/Theory of computation/Turing Machine

* From the Specification : Turing Machine and the Universal Machine.
* The abstract model of the Turing Machine and the Universal Machine..

## Recap

Before attempting to study Turing Machines you should ensure you are familiar with Finite State machines from the AS Computing specification and the few additional FSM concepts added to the A2 course.

## Definition

Turing machines provide a general or formal model of computation and can be used to determine whether or not a task is computable. OR A formal model of computation that consists of a finite state machine (FSM) that controls one or more tapes, where at least one tape is of unbounded length (ie infinitely long).

## Universal Turing Machine

A universal Turing machine (UTM) is a Turing machine that can execute other Turing machines by simulating the behaviour of any Turing machine. If a sequence is computable then a UTM will be able to execute it. A UTM behaves as an interpreter which is just what a PC does when it runs a Java applet or Flash script.
Rather than each individual process within a single machine, the UTM takes two inputs:
* A description of all the individual Turing machines required to perform the calculations
* All the inputs required for the calculations
Principle of Universality: A universal machine is a machine capable of simulating any other machine.

## Examples of mechanical Turing Machines

* A Turing Machine "in the classic style" has an excellent video depicting the operation of a physical Turing machine

## Simulations

* Turing Kara has some excellent instructions to help you get to grips with the basic operations of a turing machine

## Example Questions

* Exercise: Turing Machines
* What is a Turing machine?
* Answer:
* A Finite State Machine that operates one or more tapes where at least one tape is infinitely long

## Revision

* Turing machines flash cards with test and other activities
# A-level Computing/AQA/Paper 1/Theory of computation/Regular expressions

You will often want to check the format of a string being input and if it is incorrect you will want it to be submitted again. For example you might want someone to input the name of their best friend, meaning that they shouldn't be inputting any letters or spaces, and it should start with a capital letter:
Name of best friend: Beanie //(CORRECT) Name of best friend: jonny5 //(STOP THIS)
To do this we can match the input string against some rules, regular expressions or regex, in this case we only want characters from the alphabet:
    [A-Z][a-z]+
Breaking apart the rule:
* [A-Z] - start exactly one instance of a capital letter
* [a-z]+ - followed by as many lower case letters as you like (that's what the + means)
Another example might be checking for the correct spelling of a famous composer:
We can check this using the pattern H(ä|ae?)ndel. Let's take a look at what this means:
* H - start with an H
* (ä|ae?) - includes an ä or (the | symbol) an a followed by an optional e (e? means the e is optional)
Most regular expression tools provide the following operations to construct expressions.
Boolean "or"
A vertical bar separates alternatives. For example, gray|grey can match "gray" or "grey".
Grouping
Parentheses are used to define the scope and precedence of the operators (among other uses). For example, gray|grey and gr(a|e)y are equivalent patterns which both describe the set of "gray" and "grey".
Quantification
A quantifier after a token (such as a character) or group specifies how often that preceding element is allowed to occur.
* ? The question mark indicates there is zero or one of the preceding element. For example, colou?r matches both "color" and "colour".
* * The asterisk indicates there is zero or more of the preceding element. For example, ab*c matches "ac", "abc", "abbc", "abbbc", and so on.
* + The plus sign indicates there is one or more of the preceding element. For example, ab+c matches "abc", "abbc", "abbbc", and so on, but not "ac".
Most programming languages have regular expression functions. In VB.NET we can use regular expressions by using the Regex routine:
A common use for regular expressions is in checking that you have a correctly typed email address. A rule for that is this: ^[a-zA-Z0-9_.+-]+@[a-zA-Z0-9-]+\.[a-zA-Z0-9-.]+$.
You can find out more about Regular expression on wikipedia and you will cover regular expressions in more detail in A2.
# A-level Computing/AQA/Paper 1/Theory of computation/Order of complexity
## Order of Complexity

| Notation | Name | Example |
| $O(1)\,$ | constant | Determining if a number is even or odd; using a constant-size lookup table |
| $O(\log n)\,$ | logarithmic | Finding an item in a sorted array with a binary search or a balanced search tree as well as all operations in a Binomial heap. |
| $O(n)\,$ | linear | Finding an item in an unsorted list or a malformed tree (worst case) or in an unsorted array; Adding two n-bit integers by ripple carry. |
| $O(n\log n)=O(\log n!)\,$ | linearithmic, loglinear, or quasilinear | Performing a Fast Fourier transform; heapsort, quicksort (best and average case), or merge sort |
| $O(n^{2})\,$ | quadratic | Multiplying two n-digit numbers by a simple algorithm; bubble sort (worst case or naive implementation), Shell sort, quicksort (worst case), selection sort or insertion sort |
| $O(n^{c}),\;c>1$ | polynomial or algebraic | Tree-adjoining grammar parsing; maximum matching for bipartite graphs |
| $O(c^{n}),\;c>1$ | exponential | Finding the (exact) solution to the travelling salesman problem using dynamic programming; determining if two logical statements are equivalent using brute-force search |
| $O(n!)\,$ | factorial | Solving the travelling salesman problem via brute-force search; generating all unrestricted permutations of a poset; finding the determinant with expansion by minors. |
# A-level Computing/AQA/2015-ALevel-Paper1/Fundamentals of programming

* C#
* Java
* Pascal/Delphi
* Python
* VB.Net
# A-level Chemistry/OCR (Salters)/Weak acids
## Calculating the pH of a weak acid solution

The pH of a weak acid solution can be calculated approximately using the following formula:
${\mbox{pH}}=-\log _{10}{\left({\sqrt {K_{a}\left[{\mbox{acid}}\right]}}\right)}$

### Derivation

For any equilibrium
$a{\mbox{A}}+b{\mbox{B}}\rightleftharpoons c{\mbox{C}}+d{\mbox{D}}\,\!$
the equilibrium constant, K, is defined as
$K={\frac {[{\mbox{C}}]^{c}[{\mbox{D}}]^{d}}{[{\mbox{A}}]^{a}[{\mbox{B}}]^{b}}}$
Therefore, for the dissociation equilibrium of any acid
${\mbox{HA}}{\mbox{(aq)}}\rightleftharpoons {\mbox{H}}^{+}{\mbox{(aq)}}+{\mbox{A}}^{-}{\mbox{(aq)}}\,\!$
the acid dissociation constant, K$_a$, is defined as
$K_{a}={\frac {[{\mbox{H}}^{+}{\mbox{(aq)}}][{\mbox{A}}^{-}{\mbox{(aq)}}]}{[{\mbox{HA}}{\mbox{(aq)}}]}}$
Two assumptions are required:
1 The concentrations of H$^+$(aq) and A$^−$(aq) are equal, or in symbols:
    $\left[{\mbox{H}}^{+}{\mbox{(aq)}}\right]=\left[{\mbox{A}}^{-}{\mbox{(aq)}}\right]$
    The reason this is an approximation is that a very slightly higher concentration of H$^+$(aq) exists in reality, due to the autodissociation of water, H$_2$O(l) ⇌ H$^+$(aq) + A$^−$(aq). We neglect this effect since water produces a far lower concentration of H$^+$(aq) than most weak acids. If you were studying an exceptionally weak acid (you won't at A-level), this assumption might begin to cause big problems.
2 The amount of HA at equilibrium is the same as the amount originally added to the solution.
    $\left[{\mbox{HA}}{\mbox{(aq)}}\right]=\left[{\mbox{acid}}\right]$
    This cannot be quite true, otherwise HA wouldn't be an acid. It is, however, a close numerical approximation to experimental observations of the concentration of HA in most cases.
The effect of assumption 1 is that
$K_{a}={\frac {[{\mbox{H}}^{+}{\mbox{(aq)}}][{\mbox{A}}^{-}{\mbox{(aq)}}]}{[{\mbox{HA}}{\mbox{(aq)}}]}}$
becomes
$K_{a}={\frac {[{\mbox{H}}^{+}{\mbox{(aq)}}]^{2}}{[{\mbox{HA}}{\mbox{(aq)}}]}}$
The effect of assumption 2 is that
$K_{a}={\frac {[{\mbox{H}}^{+}{\mbox{(aq)}}]^{2}}{[{\mbox{HA}}{\mbox{(aq)}}]}}$
becomes
$K_{a}={\frac {[{\mbox{H}}^{+}{\mbox{(aq)}}]^{2}}{[{\mbox{acid}}]}}$
which can be rearranged to give
$[{\mbox{H}}^{+}{\mbox{(aq)}}]^{2}=K_{a}\left[{\mbox{acid}}\right]$
and therefore
$[{\mbox{H}}^{+}{\mbox{(aq)}}]={\sqrt {K_{a}\left[{\mbox{acid}}\right]}}$
By definition,
${\mbox{pH}}=-\log _{10}{\left(\left[{\mbox{H}}^{+}{\mbox{(aq)}}\right]\right)}$
so
${\mbox{pH}}=-\log _{10}{\left({\sqrt {K_{a}\left[{\mbox{acid}}\right]}}\right)}$
# A-level Chemistry/OCR (Salters)/What's in a Medicine?

What's in a Medicine? is the sixth unit in the Salters Advanced Chemistry course.

## Chemical Storylines sections

* WM1 The development of modern ideas about medicines
* WM2 Medicines from nature
* WM3 Identifying the active chemical from willow bark
* WM4 Instrumental analysis
* WM5 The synthesis of salicylic acid and aspirin
* WM6 Delivering the product
* WM7 The miraculous medicine
* WM8 Development and safety testing of medicines
* WM9 Summary

## Chemical Ideas sections

* 2.1 A simple model of the atom (revision)
* 3.5 Geometric isomerism (revision)
* 6.4 Infrared spectroscopy
* 6.5 Mass spectrometry
* 13.2 Alcohols and ethers (revision)
* 13.3 Carboxylic acids and their derivatives
* 13.4 The –OH group in alcohols, phenols and acids
* 13.5 (part b) Esters

## Activities

* WM1 The origins and development of the modern pharmaceutical industry
* WM2 Extraction of salicylic acid
* WM3 Investigating the chemistry of the –OH group in various environments
* WM4 Interpretation of the mass spectrum of salicylic acid
* WM5.1 A preparation of aspirin
* WM5.2 Using spectroscopy
* WM6 An aspirin assay
* WM8 Which product should a pharmaceutical company develop?
* WM9 Check your notes on What’s in a Medicine?

## External links

* WM unit map
* WM Check Your Notes
# A-level Chemistry/OCR (Salters)/The Steel Story

The Steel Story is the ninth unit in the Salters Advanced Chemistry course.

## Chemical Storylines sections

* SS1 What is steel?
* SS2 How is steel made?
* SS3 Rusting
* SS4 Recycling steel
* SS5 A closer look at the elements in steel
* SS6 Summary

## Chemical Ideas sections

* 2.4 Electronic structure: sub-shells and orbitals (revision)
* 6.1 Light and electrons (revision)
* 6.7 Where does colour come from?
* 9.1 Oxidation and reduction (revision)
* 9.2 Redox reactions and electrode potentials
* 9.3 Predicting the direction of redox reactions
* 11.5 The d block: characteristics of transition elements
* 10.5 How do catalysts work? (revision)
* 11.6 The d block: complex formation

## Activities

* SS1.1 How much manganese is there in a paper clip?
* SS1.2 A redox titration
* SS2.1 Why is blast furnace iron so impure?
* SS2.2 What changes occur during steelmaking?
* SS2.3 Getting the ‘heat balance’ right (Optional extension)
* SS2.4 How much aluminium do we need to add? (Optional extension)
* SS2.5 Which is the right steel for the job? (Optional extension)
* SS3.1 A simple redox reaction
* SS3.2 Simple electrochemical cells
* SS3.3 More electrochemical cells
* SS3.4 How does steel rust?
* SS3.5 Understanding redox reactions
* SS5.1 Investigating the oxidation states of vanadium
* SS5.2 How do transition metal ions act as catalysts?
* SS5.3 Looking at some transition metal complexes
* SS6 Check your notes on The Steel Story

## External links

* SS unit map
* SS Check Your Notes
# A-level Chemistry/OCR (Salters)/Visiting the Chemical Industry

Visiting the Chemical Industry is the fourteenth and final unit in the Salters Advanced Chemistry course.

## Chemical Storylines sections

* VCI1: Introduction
* VCI2: Research and development
* VCI3: Building the chemical plant
* VCI4: People
* VCI5: Safety matters
* VCI6: Environmental issues
* VCI7: Location
* VCI8: Choosing a feedstock
* VCI9: Making a profit
* VCI10: Summary

## Chemical Ideas sections

* 15.1 The operation of a chemical manufacturing process
* 15.2 Feedstocks
* 15.3 The best conditions for the process
* 15.4 Becoming even more efficient
* 15.5 Costs

## Activities

* VCI1 Your visit to the chemical industry
* VCI7 Setting up a new chemical plant
* VCI10 Check your notes on Visiting the Chemical Industry

## External links

* VCI unit map
* VCI Check Your Notes
# A-level Computing

This is a book about A-Level Computer Science. It aims to fit in with the AQA and OCR GCE A-Level Computer Science syllabus but is not endorsed by either. It should be useful as a revision guide or to find alternative explanations to the ones in your textbook. If you haven't heard of an A-Level then this book probably won't be of much interest to you but you can find out about them at Wikipedia.
If any part of this book is unclear or even wrong then please post a comment on the discussion page or simply fix it yourself! In particular, please say if the book assumes any knowledge or skills which not all A-Level Computing students have.

## Contents

* AQA
* CIE
* OCR
* WJEC (Eduqas)

### Appendices

* ICT Projects using LAMP
* Exam Tips
* Authors