A plat consists of a map, drawn to scale, showing the divisions of a piece of land. U.S. General Land Office surveyors drew township plats to show the distance and bearing between survey corners, and sometimes included topographic or vegetation information. City, town or village plats show subdivisions into blocks with streets and alleys. Further refinement often splits blocks into individual lots, usually for the purpose of selling the described lots; this has become known as subdivision. After the filing of a plat, legal descriptions can refer to block and lot-numbers rather than portions of sections.

In order for plats to become legally valid, a local governing body, such as a public works department, urban planning commission, or zoning board must normally review and approve them.

Types of plats

A Plat of Consolidation originates when a landowner takes over several adjacent parcels of land and consolidates them into a single parcel. In order to do this, the landowner will usually need to make a survey of the parcels and submit the survey to the governing body that would have to approve the consolidation.

A Plat of Subdivision appears when a landowner or municipality divides land into smaller parcels. If a landowner owns an acre of land, for instance, and wants to divide it into three pieces, a surveyor would have to take precise measurements of the land and submit the survey to the governing body, which would then have to approve it.

A Correction Plat or Amending Plat records minor corrections to an existing plat, such as correcting a surveying mistake or a scrivener's error. Such plats can sometimes serve to relocate lot-lines or other features, but laws usually tightly restrict such use.

A Vacating Plat functions to legally void a prior plat or portion of a plat. The rules normally allow such plats only when all the platted lots remain unsold and no construction of buildings or public improvements has taken place.

Other names associated with Parcel Maps are: Land Maps, Tax Maps, Real Estate Maps, Landowner Maps, Lot and Block Survey System and Land Survey Maps. Parcel maps, unlike any other public real estate record, have no federal, state or municipal oversight with their development.

Reasons for platting

• Designation of roads or other rights of way.
• Ensuring that all property has access to a public right of way. Without such access, a property owner may be unable to utilize his or her property without having to trespass to reach it. The platting process restricts the fraudulent practice of knowingly selling lots with no access to public right of way.
• Creation or vacation of easements.
• Dedication of land for other public uses, such as parks or areas needed for flood protection.
• Ensuring compliance with zoning. Zoning regulations frequently contain restrictions that govern lot sizes and lot geometry. The platting process allows the governing authorities to ensure that all lots comply with these regulations.
• Ensuring compliance with a land use plan established to control the development of a city.
• Ensuring that all property has access to public utilities.

Reading a Plat

Plats contain a number of informational elements:

• The property boundaries are indicated by bearing and distance. The bearing is in the format of degrees, minutes, seconds with compass point letters before and afterward to indicate the compass quadrant. For example N 38 00 00 E is 38 degrees into the northeast quadrant or 38 degrees east of north. Similarly S 22 00 00 W is 22 degrees west of south. Note that north here is true north, so magnetic orientation must be corrected for magnetic declination. (Explanatory graphic)
• The certification note provides information on the surveyor and is the location where recent US plats place the flood survey code in accordance with the National Flood Insurance Act of 1968.
• The north arrow is familiar to most map readers
• The title block and lot numbers provide information specific to a development or land use plan
• An easement is usually indicated by a dashed line, although it is also common to have to look them up in supplementary documents (such as a title report)
• Streets are usually indicated by a graphical outline of the right of way, and sometimes depicts the paved area.

History

The word "plat" in medieval English (and ever since) refers to a piece (or "plot") of land.

The creation of a plat map marks an important step in the process of incorporating a town or city according to United States law. Because the process of incorporation sometimes occurred at a courthouse, the incorporation papers for many American cities may be stored hundreds of miles away in another state.

For example, to view the original plat for the city of San Francisco, California, filed in 1849, one must visit the Clackamas County courthouse in Oregon City, Oregon, then the capital of the Oregon Territory and the site of the closest federal land office. This happened because California did not gain statehood until 1850.

See also

• Lot and Block survey system
• plat of Zion

External links

• The U.S. National Archives and Records Administration

Tissue plasminogen activator (abbreviated tPA or PLAT) is a protein involved in the breakdown of blood clots. Specifically, it is a serine protease found on endothelial cells, the cells that line the blood vessels. As an enzyme, it catalyzes the conversion of plasminogen to plasmin, the major enzyme responsible for clot breakdown. Because it works on the clotting system, tPA is used in clinical medicine to treat stroke.

Function

The classic role of tPA is in the clotting system. Specifically, tPA catalyzes the conversion of plasminogen into plasmin. It does so by cleaving the single-chained plasminogen into two chains. These two chains are linked by a disulfide bond and the resulting molecule is called plasmin.

Increased enzymatic activity causes hyperfibrinolysis, which manifests as excessive bleeding. Decreased activity leads to hypofibrinolysis which can result in thrombosis or embolism.

Tissue plasminogen activator also plays a role in cell migration and tissue remodeling.

Genetics

Tissue plasminogen activator is a protein encoded by the PLAT gene, which is located on chromosome 8. The primary transcript produced by this gene undergoes alternative splicing, producing three distinct messenger RNAs.

Clinical applications

Recombinant tPA is used in diseases that feature blood clots, such as pulmonary embolism, myocardial infarction and stroke. To be effective, tPA must be administered within the first three hours of the event to be given intravenously, or within six hours to be administered through an arterial catheter directly to the site of occlusion. The guideline in Ontario, Canada hospitals for ischemic strokes is that tPA must be given within 3 hours of the onset of symptoms. Because of this, only about 3% of patients qualify for this treatment. tPA appears to show benefit not only for large artery occlusions but also for lacunar strokes. Since tPA dissolves blood clots, there is risk of hemorrhage with its use.

Recently tPA has been used to dissolve thrombi associated with ischemic strokes and brain injury.

In addition, people with frostbite that were treated with tPA had fewer amputations than those that were not.

See also

• Thrombolysis
• Ultrasound-Enhanced Systemic Thrombolysis

References

Further reading

External links

• http://www.americanheart.org/presenter.jhtml?identifier=4751
• Widening the Window : Strategies to buy time in treating ischemic stroke - Scientific American Magazine (August 2005)