Sunflower

The sunflower is an annual plant in the family Asteraceae, with a large flower head. The stem of the flower can grow up to 3 meters tall, with the flower head getting 30cm in diameter. The term "sunflower" is also used to refer to all plants of the genus Helianthus, many of which are perennial plants. What is usually called the flower is actually a head of many flowers crowded together. The outer flowers are the ray florets and can be yellow, maroon, orange, or other colors. These flowers are sterile. The flowers that fill the circular head within the ray flowers are called disc florets.

The arrangement of florets within this cluster is normally such that each is separated from the next by approximately the golden angle, producing a pattern of spirals where the number of left spirals and the number of right spirals are successive Fibonacci numbers. Typically, there are 34 spirals in one direction and 55 in the other; on a very large sunflower you may see 89 in one direction and 144 in the other.

Shared web hosting service

A shared web hosting service or virtual hosting service is a form of web hosting service where more than one web site is hosted on the same server. It is generally the most economical option for hosting as many people share the overall cost of server maintenance.The hosting service must include system administration since it is shared by many users; this is a benefit for users that do not want to deal with it, but a hindrance to power users that want more control.

In shared hosting, the provider is generally responsible for management of servers, installation of server software, security updates and other aspects of the service. Servers are often based on the Linux operating systems because more Control Panel products are made for Linux. However, some providers offer Microsoft Windows based solutions. The Plesk control panel, for instance, has two versions - for Linux and Windows, both with very similar interfaces and functionality, with the exception of OS-specific differences.

Microbiology

Microbiology is the study of microorganisms, which are unicellular or cell-cluster microscopic organisms. This includes eukaryotes such as fungi and protists, and prokaryotes such as bacteria and viruses.

Although much is now known in the field of microbiology, advances are being made regularly. In actual fact, the most common estimates suggest that we have studied only about 1% of all of the microbes in any given environment. Thus, despite the fact that over three hundred years have passed since the discovery of microbes, the field of microbiology is clearly in its infancy relative to other biological disciplines such as zoology, botany or even entomology.

Perception of sound

Sound is perceived through the sense of hearing. Humans and many animals use their ears to hear sound, but loud sounds and low frequency sounds can be perceived by other parts of the body through the sense of touch. Sounds are used in several ways, most notably for communication through speech or, for example, music. Sound can also be used to acquire information about properties of the surrounding environment such as spatial characteristics and presence of other animals or objects. For example, bats use echolocation, ships and submarines use sonar, and humans can determine spatial information by the way in which they perceive sounds.

The range of frequencies that humans can hear is approximately between 20 Hz and 20,000 Hz. This range is by definition the audible spectrum, but some people (particularly women) can hear above 20,000 Hz.