Is New Year's day always January 1st ? ( special edition )

HAPPY NEW YEAR 2011 ! This special post from me. health blog that reviews the New Year ! hopefully in 2011, we all can become better people , amin .

People around the world celebrate New Year’s Day on January 1. But the new year begins at other times, too. The Chinese New Year begins between January 21 and February 19. The Jewish New Year begins in autumn. The Muslim New Year falls 11 days earlier each year than the last. Why? Because there are many ways to arrange a calendar.

WHY WE USE CALENDARS

A calendar is a way of measuring time to help people organize their activities. Calendars divide time into fixed periods, such as days, weeks, months, and years.

Long ago, when people learned to farm, they needed an accurate way to measure time and the changing seasons. They used calendars. Calendars helped them establish the best time to till the soil and plant crops. Calendars told them when the harvest should begin.

The time periods used in calendars are based on movements of the Earth, Moon, and Sun. But a year does not divide evenly into months or days. So people have adjusted their calendars so that certain events, such as a harvest or important holiday, always occur during the right season.

ANCIENT CALENDARS

The first calendars were lunar calendars. They were based on the Moon. One month meant the time from one full moon to the next. That’s about 29.5 days. Some early lunar calendars alternated between months with 29 days and months with 30 days.

Measuring a year was harder. People knew that it equaled about 12 months, but not exactly. For farmers, it was important to measure a year accurately. That required a solar calendar, based on the Sun.

A solar year is the time it takes for Earth to make one trip around the Sun. About 6,000 years ago, the Egyptians became the first people to measure a year as 365 days. But a solar year is just a little longer than that. In fact, it’s about six hours longer.

Over time, these extra hours add up. Solar calendars gradually lose their accuracy. After four years, for example, a solar calendar will be off by about 24 hours, or a full day.

THE JULIAN CALENDAR

In 45 bc, the Roman general Julius Caesar reformed the old Roman lunar calendar. The new calendar became known as the Julian calendar. It had 12 months and was based on the Sun. A year lasted 365 days. Every fourth year a day was added, making the year 366 days long.

These longer years are called leap years. This is because the extra day causes all the days following it to “leap” forward.

OUR MODERN CALENDAR

The Julian calendar was used for hundreds of years. But it still contained a small error. The Julian calendar’s year was 11 minutes and 14 seconds longer than the actual solar year. By the 1500s, the Julian calendar was off by ten days!

In 1582, Pope Gregory XIII introduced a more accurate calendar. To avoid the old error, the new calendar changed the way leap years were added. Most of the world uses the Gregorian calendar today.

WHAT ABOUT WEEKS?

A week is not a natural division of time. It may come from the ancient Hebrew custom of resting every seventh day. The Romans named the days of the week after the Sun, Moon, and planets. The English names for days still show the Roman influence. Sunday and Monday, for example, come from the Roman words for Sun and Moon.
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What is Bacteria ?

Peek into a clean room with no one in it. There are no pets in the room. There are no plants in the room. It looks like there is nothing alive in the room. The room, however, is swarming with life. Billions of tiny life forms called bacteria cover the tables and chairs and the floor. You can’t see them, but they stick to the windows, they cling to the ceiling, and they float through the air.

Suppose you looked at part of a chair in the room through a microscope. Microscopes magnify bacteria. You would see pale forms moving and bumping into each other like ghosts. These tiny life forms are bacteria. They live everywhere in the world. Billions of them even live inside of you!

WHAT DO BACTERIA LOOK LIKE?

Bacteria come in three basic shapes. Some are round or shaped like a jellybean. Some are spiral-shaped like a corkscrew. Some are long, like rods.

Each sphere or spiral or rod is called a cell. Animals have millions of cells, but bacteria have only one cell. This single bacterial cell is called a bacterium. An outer wall surrounds the cell and protects it. A substance called DNA floats around inside the cell.

Some bacteria have hairlike parts called flagella. The flagella help the bacteria move around in search of food. Flagella also move bacteria away from things that could harm them.

WHAT DO BACTERIA DO?

Some bacteria help you. Bacteria in the body help fight off disease and help you digest your food. Some bacteria that live in soil help plants by producing substances plants need. They break down dead plants and animals and animal waste. They make a gas called carbon dioxide from decaying material. Other bacteria help plants take a gas called nitrogen out of the air. Plants need carbon dioxide and nitrogen in order to grow.

Some bacteria can harm you. There are bacteria that cause food poisoning, pneumonia, tuberculosis, and other sicknesses. Some bacteria cause tooth decay. Bacteria can also infect farm animals and wild animals.

Disease-causing bacteria are different from helpful bacteria. You can swallow disease-causing bacteria in unclean food or water. Bacteria that cause infections can get into cuts and sores. Bacteria can get on your hands and go from your hands into your nose, eyes, or mouth. That is why it is so important to wash your hands often.

HOW DO BACTERIA GROW AND SPREAD?

Most bacteria simply split in two. Bacteria reproduce very rapidly. One bacterial cell can become two in just a few minutes. Two bacteria become four bacteria and then four become eight bacteria. Bacteria keep multiplying this way until there are billions of them.

Different kinds of bacteria must compete for food. This competition keeps bacteria from overrunning Earth.

WHO DISCOVERED BACTERIA?

No one knew about bacteria until the microscope was invented. Bacteria are so small that they must be magnified at least 500 times their actual size for us to see them.

A Dutch microscope-maker named Antoni van Leeuwenhoek in the 1670s was the first person to see bacteria under a microscope. He saw tiny life forms swimming around in drops of rainwater and in scrapings from his teeth. He called the bacteria “animalcules,” meaning tiny animals.

French scientist Louis Pasteur in the 1800s proved that some bacteria are germs that cause disease. He found that heat kills bacteria. Heating surgical instruments to kill bacteria is called sterilization. Heating milk and other foods to kill bacteria is called pasteurization, a word named for Pasteur.

A German scientist named Robert Koch also made important discoveries about bacteria. He founded a field of science called bacteriology, the study of bacteria.

WHY DO WE STUDY BACTERIA?

Scientists study bacteria to find out how these tiny life forms behave. Scientists also want to know what diseases bacteria cause. They look for ways to kill disease-causing bacteria.

In the mid-1800s, scientists learned that killing bacteria can stop the spread of some diseases. Doctors learned that sterile surgical instruments and operating rooms help prevent infection after operations. Scientists learned that having clean drinking water and food prevents the spread of deadly diseases such as cholera and typhoid.

Scientists also learned how to make vaccines that protect against some diseases caused by bacteria. They made vaccines from dead or weakened bacteria or from poisons bacteria produce. For example, a shot of tetanus vaccine protects you from the bacteria that cause tetanus. Tetanus bacteria live in the soil. They can get into even small cuts on your body. Tetanus causes muscles to tighten. It can be deadly.

In the mid-1900s, scientists discovered antibiotics, drugs that kill bacteria. Before antibiotics, many people died from pneumonia and other infections caused by bacteria. Some bacteria have become resistant to antibiotics. The antibiotics no longer kill them. Scientists are working to make new kinds of antibiotics that will kill resistant bacteria.
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What is Vaccination ?

“You’ll just feel a little jab.” Ouch! That wasn’t too bad, and it could save your life. Most of us have had “shots” from a needle. These are usually vaccinations, and they are extremely valuable. They help protect us against diseases.

VIRUSES

Most vaccinations are given to protect against diseases caused by viruses. Viruses are germs, and they are extremely tiny. They infect (get into) your body, multiply, and make you feel sick. Chicken pox is one example of a disease caused by a virus. The chicken pox virus gets inside the body and multiplies. It causes a fever followed by a rash of itchy red spots.

WHAT ARE VACCINES?

A vaccine is usually a small amount of liquid that contains dead or weakened versions of a virus or other type of germ. Weakened viruses can still multiply within the body but cannot cause disease. Vaccines can also contain tiny amounts of harmful substances, called toxins, which are made by the viruses. But they don’t have enough toxin to make you sick.

Some vaccines are oral, which means you can eat them or drink them. However, the powerful digestive juices in your stomach would destroy most vaccines. So vaccines are usually given by needle.

BECOMING IMMUNE

Your body attacks and destroys the weakened virus or toxin in the vaccine before it can make you sick. In this way, you become immune to (protected from) the disease the virus causes. The vaccine enables the body’s defenses, or immune system, to recognize and destroy the virus.

To destroy the virus, your immune system produces special substances, called antibodies, in the blood. Antibodies are able to fight and destroy particular viruses. If the real virus later invades, the immune system can kill it very quickly, before it starts to multiply.

WHICH DISEASES?

Vaccination is carried out in many countries as a regular part of healthcare. Vaccines are usually given to babies and young children so that they are protected from diseases as soon as possible. Vaccines exist for many diseases, including chicken pox, measles, mumps, rubella, polio, diphtheria, tetanus, and whooping cough.

Some of these vaccines are given to almost everyone. Others are given only to people who are considered likely to get the disease, perhaps because of where they live or their age. Several vaccines may be given at the same time as a combined vaccine. For example, the MMR vaccine protects against measles, mumps, and rubella.

Some vaccines only make you immune for a few months or years. They include vaccines against typhoid fever, cholera, tetanus, and yellow fever. They may need a “booster” dose later to keep up the immunity.

PROBLEMS WITH VACCINES

Sometimes giving a vaccine to a person may cause health problems. These problems are known as side effects, and they can be serious. People who have certain illnesses and conditions are more likely to have side effects. So medical workers ask questions about health before giving vaccines. Once in a while, they advise people not to get vaccinated. Medical workers must balance the risks of catching the disease with the risks of possible side effects of vaccination.

CHANGING VIRUSES

Viruses can change, or mutate, over time. A vaccine against one strain of a mutated virus may not work against another strain. The flu (influenza) is one of these viruses that mutate into different strains. A new vaccine for the flu has to be developed every year.

Every now and then a new kind of germ appears. One example is HIV (human immunodeficiency virus), which causes a disease called AIDS (acquired immune deficiency syndrome). No one knew about HIV until the 1980s. When new viruses appear, medical scientists try to develop new vaccines against them. It is a long and difficult process. But vaccination is one of our most powerful medical weapons in the battle against diseases.
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