Everything about In Situ totally explained
In situ is a
Latin phrase meaning
in the place. It is used in many different contexts.
Aerospace
In the aerospace industry equipment on board aircraft must be tested "in situ" or in place to confirm everything functions properly as a system. Individually each piece may work but interference from nearby equipment may create problems not anticipated. Special test equipment is available for this "in situ" testing.
Archaeology
In archaeology,
in situ refers to an artifact that hasn't been moved from its original place of deposition, in other words is stationary meaning "Still". An artifact being
in situ is critical to the interpretation of that artifact and, consequently, to the culture which formed it. Once an artifact's 'find–site' has been recorded, the artifact can then be moved for conservation, further interpretation and display. An artifact that isn't discovered
in situ is considered out of context and won't provide an accurate picture of the associated culture. However, the out of context artifact can provide scientists with an example of types and locations of
in situ artifacts yet to be discovered.
In situ only expresses that the object hasn't been
newly moved. Thus, an archaeological in–situ–find may be an object that was historically looted from another place, an item of "booty" of a past war, a traded item or otherwise of foreign origin. Consequently, the
in situ find site may still
not reveal its
provenance but with further detective work may help uncover links that otherwise would remain unknown. It is also possible for archaeological layers to be reworked on purpose or by accident (by humans, natural forces or animals), for example in a
tell mound where layers are not typically uniform or horizontal or in land cleared or tilled for farming.
Architecture
In
architecture and
building,
in situ means construction which is carried out on the building site using raw materials. Compare that with
prefabricated construction, in which building components are made in a factory and then transported to the building site for assembly. For example,
concrete slabs may be
in situ or
prefabricated.
In situ techniques are often more labour-intensive, and take longer, but the materials are cheaper, and the work is versatile and adaptable.
Prefabricated techniques are usually much quicker, therefore saving money, but factory-made parts can be expensive. They are also inflexible, and must often be designed on a grid, with all details fully calculated in advance. Finished units may require special handling due to excessive dimensions.
Astronomy
Future space exploration or
terraforming may rely on obtaining supplies
in situ, such as previous plans to power the
Orion space vehicle with fuel minable on the moon.
Mars Direct mission concept is based primarily on the
in situ fuel production using
Sabatier reaction.
A fraction of the globular star clusters in our Galaxy, as well as those in other massive galaxies, might have formed
in situ. The rest might have been accreted from now defunct dwarf galaxies.
Biology
In
biology,
in situ means to examine the phenomenon exactly in place where it occurs (for example without moving it to some special medium). This usually means something intermediate between
in vivo and
in vitro. For example, examining a within a whole
organ intact and under
perfusion may be
in situ investigation. This wouldn't be
in vivo as the donor is sacrificed before experimentation, but it wouldn't be the same as working with the cell alone (a common scenario in
in vitro experiments).
In-vitro was the first of mankind’s attempts to qualitatively and quantitatively analyze natural occurrences in the lab. Eventually, the limitation of in-vitro experimentation was that they were not conducted in natural environments. To compensate for this problem, in-vivo experimentation allowed testing to occur in the originate organism or environment. To bridge the dichotomy of benefits associated with both methodologies, in-situ experimentation allowed the controlled aspects of in-vitro to become coalesced with the natural environmental compositions of in-vivo experimentation.
In
oncology: for a
carcinoma,
in situ means that
malignant cells are present as a tumor but hasn't metastasized, or invaded, beyond the original site where the tumor was discovered. This can happen anywhere in the body, such as the skin, breast tissue, or lung.
In conservation of
genetic resources, "
in-situ conservation" (also "on-site
conservation") is the process of protecting an
endangered plant or
animal species in its natural
habitat, as opposed to
ex-situ conservation (also "off-site conservation").
Chemistry and chemical engineering
In chemistry, in situ typically means "in the reaction mixture."
There are numerous unstable molecules which must be synthesized
in situ (for example in the reaction mixture but can't be isolated on their own) for use in various processes. Examples include the
Corey-Chaykovsky reagent and
adrenochrome.
In chemical engineering, in situ often refers to industrial plant "operations or procedures that are performed in place". For example, aged catalysts in industrial reactors may be regenerated in place (in situ) without being removed from the reactors.
Computer science
In
computer science an
in situ operation is one that occurs without interrupting the normal state of a system. For example, a file backup may be restored over a running system, without needing to take the system down to perform the restore. In the context of a database, a restore would allow the database system to continue to be available to users while a restore happened. An
in situ upgrade would allow an operating system or application to be upgraded while the system was still running, perhaps without the need to reboot it, depending on the sophistication of the system.
An
algorithm is said to be an
in situ algorithm, or in-place algorithm, if the amount of memory required to execute the algorithm is
O(1), that is, doesn't depend on the size of the input. For example,
heapsort is an in situ sorting algorithm.
In designing user interfaces, the term
in situ means that a particular user action can be performed without going to another window, for example, if a word processor displays an image and allows you to edit the image without launching a separate image editor, this is called
in situ editing.
Earth and atmospheric sciences
In
physical geography and the
Earth sciences,
in situ typically describes natural material or processes prior to transport. For example,
in situ is used in relation to the distinction between
weathering and
erosion, the difference being that erosion requires a transport medium (such as
wind,
ice, or
water), whereas weathering occurs
in situ.
Geochemical processes are also often described as occurring to material
in situ.
In the
atmospheric sciences,
in situ refers to obtained through direct contact with the respective subject, such as a
radiosonde measuring a parcel of air or an
anemometer measuring wind, as opposed to
remote sensing such as weather radar or satellites.
Environmental engineering
In situ can refer to where a clean up or
remediation of a
polluted site is performed using and simulating the natural processes in the
soil, contrary to
ex situ where contaminated soil is
excavated and cleaned elsewhere, off site.
Literature
In
literature in situ is used to describe a condition. The
Rosetta Stone, for example, was originally erected in a courtyard, for public viewing. Most pictures of the famous stone are not
"in-situ" pictures of it erected, as it would have been originally. The stone was uncovered as part of building material, within a wall. Its
in situ condition today is that it's erected, vertically, on public display at the
British Museum.
Linguistics
In
linguistics, specifically
syntax, an element may be said to be
in situ if it's pronounced in the position where it's interpreted. For example,
questions in languages such as
Chinese have
in-situ wh-elements, with structures comparable to "John bought what?" while
English wh-elements are not
in-situ: "What did John buy?"
Law
In
legal context,
in situ is often used for its literal meaning. For example, in
Hong Kong,
in situ land exchange involves the government exchanging the original or expired
lease of a piece of land with a new
grant or re-grant with the same piece of land or a portion of that.
Petroleum production
In situ means "in place", and refers to recovery techniques which apply heat or solvents to heavy oil or bitumen reservoirs beneath the earth. There are several varieties of in situ technique, but the ones which work best in the oil sands use heat.
RF transmission
In
radio frequency (
RF) transmission systems,
in situ is often used to describe the location of various components while the system is in its standard transmission mode, rather than operation in a test mode. For example, if an
in situ wattmeter is used in a commercial broadcast transmission system, the
wattmeter can accurately measure power while the station is "on the air".
Further Information
Get more info on 'In Situ'.
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