Problem: Article: Avascular necrosis (AVN) or osteonecrosis is defined as the death of bone tissue due to lack and loss of blood supply to a particular bone. The affected bone will have tiny breaks which, overall, would lead to bone collapse. If AVN affects bones near a joint, the joint surface may collapse. Usually, the affected bone or joint area in AVN is the hip. AVN occurs in bones with a single terminal blood or end-artery supply (meaning there is a limited blood supply), such as the femoral (hip) and humeral (shoulder) heads, carpals (hand bones), and talus (foot bones). Closure or interruption of this single terminal blood supply will lead to death of bone tissue and, later, bone collapse. Although bone tissue regenerates or grows back again, the rate of bone destruction is faster than bone regeneration. If the bone collapses, the joint structure breaks down and leads to pain. Corticosteriods and radiation applied to the bone may further contribute to progression of AVN. Some causes can increase your risk of developing AVN. Any of the following can lead to AVN: A bone fracture or joint dislocation can interrupt blood flow Radiation during cancer treatment weakens the bone and affects the blood vessels Elevated pressure inside the bone causes the blood vessels to narrow and make it difficult for fresh blood to enter leading to poor blood supply Alcohol intake in huge amounts (daily for several years) causes fats to accumulate in blood vessels and block them Medications such as corticosteroids (Prednisolone) when taken on a long basis in high doses can increase your risk of AVN. Other medication such as biphosphate (a treatment for osteoporosis), when used over long periods, can lead to a rare condition called osteonecrosis of the jaw. Diseases such as diabetes, HIV/AIDS, sickle cell anemia, organ transplantation, and dialysis can lead to AVN Often AVN is missed because, early in the course of this disorder, there are no symptoms. The first symptom present is pain in the affected bone/joint such as groin pain in AVN of the femoral head. Here are the specifics: This groin pain is worsened by weight-bearing, may be mild or worsen progressively across time. Pain may occur at rest or at night. Walking with a limp may be seen in the case of the involvement of the hip joint, and pain on pressure will be felt on or around the particularly affected bone. Joint movements may be limited and painful. The affected joint may be deformed or disfigured through time. If a nerve is compressed in the area of the affected bone or joint, the muscles supplied by that nerve may be paralyzed and deformed through time. Usually, signs and symptoms occur late in the course of the disease and patients consult doctors when the disease is more advanced than it had to be. Without treatment, the affected joint will be destroyed within five years from the start of AVN. During the examination, your doctor will identify your state by pressing around the pain site checking for tenderness. He may need you to perform certain moves or body positions -- that will help in knowing if any certain movement or joint position will increase or decrease the pain, or if your movement is reduced. To determine your state and if surgery is necessary, your doctor may require any of the following: X-rays. It usually appears normal in the early stages, but in later stages it reveals clear bone change Bone scan. Via an intravenous line, a safe radioactive material is slowly injected in your vein. The material flows with your blood circulation till it reaches its destination; a picture on a special device will show the affected sites as clear bright spots. This method is commonly used when the X-ray results are normal. Magnetic Resonance Imaging "MRI". This is known as the most sensitive method for the early stages of AVN because it reveals any chemical change in the bone marrow and bone rebuilding process. This is done by radio waves and a strong magnetic field. Computerized Tomography "CT scan". This is more clear than x-rays and bone scans; it determines the extent of bone damage by taking a three dimensional picture of the bone. Bone biopsy. This is a procedure wherein a small amount of bone tissue is taken and examined using the microscope in order to view the microscopic appearance of AVN.
Summary: Know what avascular necrosis really is. Know the risk factors and causes. Know what the symptoms are. Know how AVN gets diagnosed.

Problem: Article: when it gets splattered with food. Use a cover to prevent splatters. Messy microwaves heat less efficiently.
Summary: Run the dishwasher only when it is full. Clean the inside of your microwave

Problem: Article: Above, we dealt with work problems in which the object is moving in the same direction as the force being applied to it. In reality, this isn't always the case. In cases where the force and the object's motion are in two different directions, the difference between these two directions must also be factored into the equation for an accurate result. To begin, find the magnitude of the force and the object's displacement as you normally would. Let's look at another example problem. In this case, let's say that we're pulling a toy train forward as in the example problem above, but that this time we're actually pulling upward at a diagonal angle. In the next step, we'll take this into account, but for now, we'll stick to the basics: the train's displacement and the magnitude of the force acting on it. For our purposes, let's say that the force has a magnitude of 10 newtons and that it's moved the same 2 meters (6.6ft) forward as before. Unlike in the examples above, with a force that's in a different direction than the object's motion, it's necessary to find the difference between these two directions in the form of the angle between them. If this information isn't provided to you, you may need to measure it yourself or deduce it from other information in the problem. In our example problem, let's say that the force is being applied about 60o above the horizontal. If the train is still moving directly forward (that is, horizontally), the angle between the force vector and the train's motion is 60o. Once you know the object's displacement, the magnitude of the force acting on it, and the angle between the force vector and its motion, solving is almost as easy as it is without having to take the angle into account. Simply take the cosine of the angle (this may require a scientific calculator) and multiply it by force and displacement to find your answer in joules. Let's solve our example problem. Using a calculator, we find that the cosine of 60o is 1/2. Plugging this into the formula, we can solve as follows: 10 newtons 2 meters (6.6ft) 1/2 = 10 joules.
Summary:
Find the force and displacement as normal. Find the angle between the force vector and the displacement. Multiply Force Distance Cosine().