Multitasking means that a computer can run more than one item of software in the same time frame, as in switching between several computer programs running on a single CPU. It can also refer to a person who is working on more than one task at the same time (for instance, talking on the telephone while filing papers).
Computers which can appear to run more than one program even with only one CPU. Computer scientists solve the problem that a CPU can only do one thing at a time by programming it so that it switches rapidly between tasks. This happens so rapidly that it appears that the computer is running more than one program at once. This is called "multiprogramming". This action is often controlled by the operating system (OS) controlling the hardware of the system.
The more things the computer has to do at once, the more time it has to spend deciding which to give more time to, and the less time each one receives. This tends to make the computer perform its tasks more slowly, unless it uses a multi-core processor, acting as multiple CPUs, which is called "multiprocessing".
Multithreading
Multithreading means that a computer can work on different parts of the same program at the same time. This usually allows the program to run faster.
Fertilization
Fertilization (British English spelling: fertilisation) is when a male's sperm enters a female's ovum (or "egg"). Fertilization is also called "conception". Biologists call a fertilized egg a zygote. A zygote grows into an embryo.
Fertilization occurs in animals, including humans and birds, in plants, fungi, protists, in fact all eukaryotes. Fertilization makes a cell with twice as many chromosomes. The eukaryote life cycle includes meiosis which divides the chromosome number in half.
In animals, there are two types of fertilization, internal and external. Internal fertilization happens in the female body. External fertilization happens outside of the body. Mammals, birds, and reptiles use internal fertilization. Amphibians and most fish use external fertilization. Some animals with internal fertilization give birth to live offspring. Others such as birds, most reptiles, and some mammals such as the Platypus, lay eggs.
Internal fertilization happens during mating (sexual intercourse in humans). Sperm cells travel from the male testicles to the female uterus. One sperm attaches to the egg in the uterus. Together, they become a zygote.
Decision
Decision can mean:
Whiteboard
A whiteboard, also called a markerboard, is a drawing surface on which markings made with markers are visible. It is used as a surface to write on. Whiteboards are often used to help teach. Special markers are used that can be erased. Whiteboards usually have a shiny surface. Before there were whiteboards, people used blackboards. Chalk is used to write on blackboards. Now, there is another improvement, people are now using electronic whiteboards, where it is controlled by a computer - this is sometimes called an interactive whiteboard (IWB). These were particularly popular in English schools in the 2000s.
Chemist
A chemist is a scientist who studies chemistry. In England can also mean a pharmacist (person who dispenses medicines that doctors prescribe for people).
Chemistry is the study of elements, atoms, molecules, and how they react together. Chemists research and test medicines, explosives, and a lot of other things. Chemistry is an important science. It helps industry and pharmacology.
Chemists are people who study compounds and find new ways to do chemical reactions. They make chemicals in order to find new ways to do things, like to make a better glue, or to make new medicines, or to make things clean, for example. They also use compounds to find out more about the laws of chemistry.
Biologist
A biologist is a scientist who studies biology. Biologists study living organisms.
There are many different kinds of biologists. Some of these include:
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Testicular cancer
Testicular cancer is cancer in one or both testicles, a part of the male reproductive system. In the United States, about 8,000 to 9,000 people are diagnosed with the cancer every year. Every male has a 1 in 250 (four tenths of one percent, or 0.4%) chance of being diagnosed with it. It is most common among males aged 15-40 years. Testicular cancer has one of the highest cure rates of all cancers; more than 90%. This is most often achieved by removing one or both testicles. Even in the small number of cases where the cancer has spread widely, chemotherapy offers a cure rate of at least 50%.
Because testicular cancer is curable (stage I can have a success rate of >95%) when detected early, experts recommend regular monthly testicular self-examination after a hot shower or bath, when the scrotum is looser. Men are advised to feel each testicle, feeling for pea-shaped lumps.
Symptoms of testicular cancer include one or more of the following:
How bad the cancer is and whether it is present at all is often discovered through ultrasound of the testicles, x-rays, and/or CT scans. Blood tests are also used to identify and measure tumour markers that are only in a person's blood if they have testicular cancer. Biopsies should not be performed because it increases the risk of migrating cancer cells into the scrotum.
Future
The future is something that has not happened yet. Once that something has happened, it is called the past. If it is happening now, it is called the present.
Movies, television shows and books that tell made-up stories about the future are often called science fiction, but there is also science fiction which takes place in the past, and fiction that takes place in the future but is not science fiction.
Fetus
A fetus or foetus is the stage that an organism goes through before it is born as a baby. In humans a fetus is the stage (time of development) after the embryonic stage, and begins during the third to eighth week of development after fertilization of the egg. The "fetal" stage lasts from 8 weeks after fertilization to birth. This stage can also take 9-12 weeks, if any mutations happen.
Past
The past is something that has already happened. If something has not happened yet, it is called the future.
Professors and researchers that study the events of the past, and try to explain why these events happened are called history professors or historians.
Many books, movies, and television shows tell made-up stories about the past. These are called historical fiction. Some books, movies, and television shows from a style called science fiction or fantasy tell made-up stories about being able to travel through time back to the past.
Particle
A particle is a tiny bit of matter that makes up everything in the universe. In particle physics, an elementary particle is a particle which cannot be split up into smaller pieces.
There are many different types of particles, with different particle sizes and properties.
"Macroscopic particles" are particles that are larger than atoms or molecules. They have volume and shape. Powder and dust are some examples of macroscopic particles. Nanoparticles are an intermediate size, being a very fine powder but much larger than atoms.
Atoms and molecules are called "microscopic particles". "Subatomic particles" are particles that are smaller than atoms. The proton, the neutron, and the electron are subatomic particles. These are the particles which make atoms. The proton has a positive charge (a + charge). The neutron has a neutral charge. The electron has a negative charge (a - charge), and it is the smallest of these three particles. In atoms, there is a small nucleus in the center, which is where the protons and neutrons are, and electrons orbit the nucleus.