bacteriophage

A bacteriophage (from 'bacteria' and Greek phagein, 'to eat') is any one of a number of viruses that infect bacteria. The term is commonly used in its shortened form, phage.

Typically, bacteriophages consist of an outer protein hull enclosing genetic material. The genetic material can be ssRNA (single stranded RNA), dsRNA, ssDNA, or dsDNA between 5 and 500 kilo base pairs long with either circular or linear arrangement. Bacteriophages are much smaller than the bacteria they destroy - usually between 20 and 200 nm in size.

Phages are estimated to be the most widely distributed and diverse entities in the biosphere. Phages are ubiquitous and can be found in all reservoirs populated by bacterial hosts, such as soil or the intestines of animals. One of the densest natural sources for phages and other viruses is sea water, where up to 9×108 virions per milliliter have been found in microbial mats at the surface, and up to 70% of marine bacteria may be infected by phages.

They have been used for over 60 years as an alternative to antibiotics in the former Soviet Union and Eastern Europe. They are seen as a possible therapy against multi drug resistant strains of many bacteria.

Algae

Algae are a large and diverse group of simple, typically autotrophic organisms, ranging from unicellular to multicellular forms. The largest and most complex marine forms are called seaweeds. They are photosynthetic, like plants, and "simple" because they lack the many of the distinct organs found in land plants. Though the prokaryotic cyanobacteria (commonly referred to as blue-green algae) were traditionally included as "algae" in older textbooks, many modern sources regard this as outdated and restrict the term algae to eukaryotic organisms. All true algae therefore have a nucleus enclosed within a membrane and chloroplasts bound in one or more membranes. Algae constitute a paraphyletic and polyphyletic group they do not represent a single evolutionary direction or line, but a level or grade of organization that may have developed several times in the early history of life on Earth.

Algae lack the various structures that characterize land plants, such as phyllids and rhizoids in nonvascular plants, or leaves, roots, and other organs that are found in tracheophytes. They are distinguished from protozoa in that they are photosynthetic. Many are photoautotrophic, although some groups contain members that are mixotrophic, deriving energy both from photosynthesis and uptake of organic carbon either by osmotrophy, myzotrophy, or phagotrophy. Some unicellular species rely entirely on external energy sources and have reduced or lost their photosynthetic apparatus.

All algae have photosynthetic machinery ultimately derived from the cyanobacteria, and so produce oxygen as a byproduct of photosynthesis, unlike other photosynthetic bacteria such as purple and green sulfur bacteria.

Mail transfer agent

A mail transfer agent (MTA) (also called a mail transport agent, message transfer agent, or smtpd (short for SMTP daemon)), is a computer program or software agent that transfers electronic mail messages from one computer to another.

The term mail server is also used to mean a computer acting as an MTA that is running the appropriate software. The term mail exchanger (MX), in the context of the Domain Name System formally refers to an IP address assigned to a device hosting a mail server, and by extension also indicates the server itself.

An MTA receives mail from another MTA (relaying), from a mail user agent (MUA), thus acting as a mail submission agent (MSA), or from an MSA that got the mail from an MUA. The MTA works behind the scenes, while the user usually interacts with the MUA. Every time an MTA receives an e-mail, it will add a "Received:" trace header field to the top of the message. In this way, there is a record of which MTAs handled the e-mail and in which order. Upon final delivery, the "Return-Path:" header will also be added to record the return path.

The delivery of e-mail to a user's mailbox typically takes place via a mail delivery agent (MDA); many MTAs have basic MDA functionality built in, but a dedicated MDA like procmail can provide more sophistication.

According to one survey, sendmail, Microsoft Exchange Server, Postfix, and Exim together control over 85% of market share for SMTP service. Another survey suggests a more balanced playing field, though it included hosted email services such as Postini.

Post trance

As an alternative evolution some artists have attempted to fuse trance with other genres such as drum'n'bass. Others have experimented with more minimalist sounds. Frustrated, extreme versions of trance have mutated through gabba into fringe genres of "hard trance" or "hardstyle" overlapping with hardcore and terrorcore.

Trance more loyal to its roots has begun to rear its head on the internet with the abundance of legal music download sites - including the likes of Juno Download, and Beatport, - enabling enthusiasts to avoid having to track down hard to find vinyl by downloading mp3s and uncompressed wavs, updated on a weekly basis. As a result, both commercial and progressive trance now have a much more global, if not chart-bound, presence, with big-draw artists such as Tiësto, ATB, Markus Schulz, Armin van Buuren, BT, Paul van Dyk, Ferry Corsten, Above & Beyond, Paul Oakenfold, Enigma, Schiller, Solarstone and the US's Christopher Lawrence and George Acosta able to maintain their esteemed positions while upcoming producers and DJs can also breakthrough into the public domain.

Lymphatic circulation

Unlike the cardiovascular system, the lymphatic system is not closed and has no central pump. Lymph movement occurs with low pressure due to peristalsis, valves, and the milking action of skeletal muscles. Like veins, lymph travels through vessels in one way only, due to semilunar valves. This depends mainly on the movement of skeletal muscles to squeeze fluid through them, especially near the joints. Rhythmic contraction of the vessel walls through movements may also help draw fluid into the smallest lymphatic vessels, capillaries. Tight clothing can restrict this, thus reducing the removal of wastes and allowing them to accumulate. If tissue fluid builds up the tissue will swell; this is called edema. As the circular path through the body's system continues, the fluid is then transported to progressively larger lymphatic vessels culminating in the right lymphatic duct (for lymph from the right upper body) and the thoracic duct (for the rest of the body); both ducts drain into the circulatory system at the right and left subclavian veins. The system collaborates with white blood cells in lymph nodes to protect the body from being infected by cancer cells, fungi, viruses or bacteria. This is known as a secondary circulatory system.