Lexikon
apoptosis is the process of programmed cell death that may occur in multicellular organisms. Programmed cell death involves a series of biochemical events leading to a characteristic cell morphology, such as blebbing, changes to the cell membrane, cell shrinkage, nuclear fragmentation, chromatin condensation, and chromosomal DNA fragmentation and finally death. Processes of disposal of cellular debris whose results do not damage the organism differentiate apoptosis from necrosis.
In contrast to necrosis, which is a form of traumatic cell death that results from acute cellular injury. Apoptosis, in general, confers advantages during an organism's life cycle. For example, the differentiation of fingers and toes in a developing human embryo occurs because cells between the fingers apoptose; the result is that the digits are separate. Between 50 and 70 billion cells die each day due to apoptosis in the average human adult. For an average child between the ages of 8 and 14, approximately 20 billion to 30 billion cells die a day. In a year, this amounts to the proliferation and subsequent destruction of a mass of cells equal to an individual's body weight.
Research in and around apoptosis has increased substantially since the early 1990s. In addition to its importance as a biological phenomenon, defective apoptotic processes have been implicated in an extensive variety of diseases. Excessive apoptosis causes hypotrophy, such as in ischemic damage, whereas an insufficient amount results in uncontrolled cell proliferation, such as cancer.
Source: Wikipedia
approved dosimetric service: a body responsible for the calibration, reading or interpretation of individual monitoring devices, or for the measurement of radioactivity in the human body or in biological samples, or for assessment of doses, whose capacity to act in this respect is recognized by the competent authorities.
Source: Council Directive 96/29 EURATOM, http://ec.europa.eu/energy/nuclear/radioprotection/doc/legislation/9629_en.pdf
approximation is a mathematical quantity that estimates a desired quantity.
aquatic toxicology is based on the response of aquatic ecosystem, both marine and freshwater. Aquatic ecosystem may investigate the whole ecosyste, the diversity of species in a certain ecosystem and compares it to the healthy state of the same ecosystem. According to an other concept toxicology applies toxicity tests on some selected memberes of the aquatic ecosystem and from these results extrapolates on the total ecosystem. The burden of failures is very high in both cases.
a subsurface layer or layers of rock or other geological strata of sufficient porosity and permeability to allow either a significant flow of groundwater or the abstraction of significant quantities of groundwater.
aquifer is a subsurface layer or layers of rock or other geological strata of sufficient porosity and permeability to allow either a significant flow of groundwater or the abstraction of significant quantities of groundwater
Sources of the definition: Directive 2000/60/EC of the European Parliament and of the Council of 23 October 2000 establishing a framework for Community action in the field of water, http://eur-lex.europa.eu/LexUriServ/LexUriServ.do?uri=OJ:L:2000:327:0001:0072:EN:PDF
agricultural land that is cultivated by ploughing, usually to 20 or 30 cm depth. More than 30 cm represents deep ploughing.
the measure, in square units, of the inside of a plane figure. The area must be a measure of a closed region or figure.
The US EPA defines a "lifelong" oral reference dose too, (abbreviated RfD) as: "an estimate, with uncertainty spanning perhaps an order of magnitude of a daily oral exposure to the human population (including sensitive subgroups) that is likely to be without an appreciable risk of deleterious effects during a lifetime.
the communication, in verbal or written form, of the reasoning process that leads to a valid conclusion; a valid argument is the result of the conjecture/reasoning process.
the simplest part of mathematics. Arithmetic means addition, subtraction, multiplication, and division (called operations). They are the foundation for all higher mathematics.
qan arrangement of objects or numbers, usually in rows and/or columns.
elemental arsenic occurs in two solid modifications: yellow, and grey or metallic, with specific gravities of 1.97, and 5.73, respectively. The element is a steel grey, very brittle, crystalline, semimetallic metalloid solid. It tarnishes in air, and when heated rapidly oxidises to arsenous oxide which has a garlic odour.
Arsenic does not often form in its elemental state and is far more common in sulfides and sulfosalts such as arsenopyrite, orpiment, realgar, lollingite and tennantite. Due to the abundance of these arsenic bearing ores and the rarity of native arsenic, it is not an important ore of itself. Native arsenic is found in silver ore veins and is processed along with the silver ore and is therefore is a minor source of arsenic.
Native arsenic is usually found to have a trigonal symmetry but a very rare orthorhombic arsenic is known from Saxony, Germany and is named arsenolamprite. The two minerals are called polymorphs many shapes because they have the same chemistry, As, but different structures.
Arsenic toxicity occurs when a person is exposed to arsenic. Arsenic is a naturally occurring element in the earth crust.
There are two primary forms of arsenic:
- Inorganic arsenic—arsenic combined with oxygen, chlorine, or sulfur; found in the environment
- Organic arsenic—arsenic combined with carbon and hydrogen; found in animals and plants.
Inorganic arsenic is usually more harmful than organic arsenic.
Arsenic occurs naturally in soil and minerals, and may enter the air, water, and soil.
In Hungary there are areas where background concentration of Arsenic is rather high 10 mg/kg in soil and 10 μg/lit in water and as consequence poses risk on human health.
Arsenic toxicity may occur when a person is exposed to toxic amounts of arsenic due to
- Breathing air containing arsenic
- Eating food contaminated with arsenic
- Drinking water contaminated with arsenic
- Living in areas with high natural levels of arsenic
- Working in a job that involves arsenic
a body of surface water created by human activity.
American Standard Code for Information Interchange
the entry of secretions or foreign material − including gaseous chemical substances, vapours of liquids or particles of solids − into the trachea and lungs. One of the exposure routes of hazardous chemicals, causing chemical pneumonia, which is an unusual type of lung irritation. Pneumonia usually is caused by a bacteria or virus. In chemical pneumonia, inflammation of lung tissue is from poisons or toxins. Only a small percentage of pneumonias are caused by chemicals.
Many substances can cause chemical pneumonia, including liquids, gases, and small particles, such as dust or fumes, also called particulate matter. Some chemicals only harm the lungs; however, some toxic materials affect other organs in addition to the lungs and can result in serious organ damage or death.
inhaling fluid or a foreign body into the bronchi and lungs, often after vomiting.
See also: aspiration
ATC code is the Anatomical Therapeutic Chemical Classification System, a system of alphanumeric codes developed by the WHO for the classification of drugs and other medical products.
atmosphere of Earth is a layer of gases surrounding the planet Earth that is retained by Earth's gravity. The atmosphere protects life on Earth by absorbing ultraviolet solar radiation, warming the surface through heat retention (greenhouse effect), and reducing temperature extremes between day and night. Dry air contains roughly (by volume) 78.09% nitrogen, 20.95% oxygen, 0.93% argon, 0.039% carbon dioxide, and small amounts of other gases. Air also contains a variable amount of water vapor, on average around 1%.
The atmosphere has a mass of about 5 × 1018 kg, three quarters of which is within about 11 km (6.8 mi; 36,000 ft) of the surface. The atmosphere becomes thinner and thinner with increasing altitude, with no definite boundary between the atmosphere and outer space. An altitude of 120 km (75 mi) is where atmospheric effects become noticeable during atmospheric reentry of spacecraft. The Kármán line, at 100 km (62 mi), also is often regarded as the boundary between atmosphere and outer space.
Source: Wikipedia
atmosphere of Earth is a layer of gases surrounding the planet Earth that is retained by Earth's gravity. The atmosphere protects life on Earth by absorbing ultraviolet solar radiation, warming the surface through heat retention (greenhouse effect), and reducing temperature extremes between day and night. Dry air contains roughly (by volume) 78.09% nitrogen, 20.95% oxygen, 0.93% argon, 0.039% carbon dioxide, and small amounts of other gases. Air also contains a variable amount of water vapor, on average around 1%.
The atmosphere has a mass of about 5 × 1018 kg, three quarters of which is within about 11 km (6.8 mi; 36,000 ft) of the surface. The atmosphere becomes thinner and thinner with increasing altitude, with no definite boundary between the atmosphere and outer space. An altitude of 120 km (75 mi) is where atmospheric effects become noticeable during atmospheric reentry of spacecraft. The Kármán line, at 100 km (62 mi), also is often regarded as the boundary between atmosphere and outer space.
Source: Wikipedia
adenosine-triphosphate, the main energy storage and transfer molecule in the cell.
attenuation in general means the reduction of a material flux, decreasing velocity of a process, the reduction of the strength of a signal or the act of thinning or weakening of any affects. The term attenuation is used in physics, in biology, microbiology, virology and in environmental sciences.
In physics/electronics it is used for the reduction of signal strength during transmission. Attenuation is the opposite of amplification, and is normal when a signal is sent from one point to another. Networks require repeaters at regular intervals to compensate attenuation. This kind of attenuation is measured in decibels.
Physical attenuation can be demonstrated by the following examples:
- light attenuation in water with depths
- transmission loss in fiber optics
- light scattering
- UV or IR absorption and selective absorption by different molecules and materials
- attenuation of radio signals
- seismic vawe attenuation, etc.
Attenuation in the biology and microbiology means mainly the thinning or weakening, such as the slowing down of the fermentation process of yeast cells paralel to the consumption of the substrates or the alteration of virulence of a pathogenic microorganism by passage through another host species, decreasing the virulence of the organism for the native host and increasing it for the new host. In gene trascription and expression attenuation means a self-regulating mechanism, resulting in the premature termination of the transcription.
In environmental management and engineering, attenuation is a process whereby the concentration of contaminants are managed, removed, or reduced by a risk reduction technology. Attenuation may be accomplished naturally under certain conditions due to dispersion, dilution, photodegradation, hídrolysis, biodegradation or the combination of all these natural processe.
Atterberg limits are a basic measure of the nature of a fine-grained soil. Depending on the water content of the soil, it may appear in four states: solid, semi-solid, plastic and liquid. In each state the consistency and behavior of a soil is different and thus so are its engineering properties. Thus, the boundary between each state can be defined based on a change in the soil's behavior. The Atterberg limits can be used to distinguish between silt and clay, and it can distinguish between different types of silts and clays.
The shrinkage limit (SL) is the water content where further loss of moisture will not result in any more volume reduction. The test to determine the shrinkage limit is ASTM International D4943. The shrinkage limit is much less commonly used than the liquid limit and the plastic limit.
The plastic limit (PL) is the water content where soil starts to exhibit plastic behavior. A thread of soil is at its plastic limit when it is rolled to a diameter of 3 mm or begins to crumble. To improve consistency, a 3 mm diameter rod is often used to gauge the thickness of the thread when conducting the test. (AKA Soil Snake Test)
The liquid limit (LL) is the water content where a soil changes from plastic to liquid behavior. The original liquid limit test of Atterberg's involved mixing a pat of clay in a little round-bottomed porcelain bowl of 10-12cm diameter. A groove was cut through the pat of clay with a spatula, and the bowl was then struck many times against the palm of one hand.
Derived indexes:
The plasticity index (PI) is a measure of the plasticity of a soil. The plasticity index is the size of the range of water contents where the soil exhibits plastic properties. The PI is the difference between the liquid limit and the plastic limit (PI = LL-PL). Soils with a high PI tend to be clay, those with a lower PI tend to be silt, and those with a PI of 0 tend to have little or no silt or clay.
The liquidity index (LI) is used for scaling the natural water content of a soil sample to the limits. It can be calculated as a ratio of difference between natural water content, plastic limit, and plasticity index: LI=(W-PL)/(LL-PL) where W is the natural water content.
The activity (A) of a soil is the PI divided by the percent of clay-sized particles(less than 0.075mm size) present. Different types of clays have different specific surface areas which controls how much wetting is required to move a soil from one phase to another such as across the liquid limit or the plastic limit. From the activity one can predict the dominant clay type present in a soil sample. High activity signifies large volume change when wetted and large shrinkage when dried. Soil with high activity are very reactive chemically.
Normally, activity of clay is between 0.75 and 1.25 and in this range, clay is called normal. It is assumed that the plasticity index is approximately equal to the clay fraction (A = 1). When A is less than 0.75, it is considered inactive. When it is greater than 1.25, it is considered active.
Source: Wikipedia, http://en.wikipedia.org/wiki/Atterberg_limits
the REACH Regulation sets up a system under which the use of substances with properties of very high concern and their placing on the market can be made subject to an authorisation requirement. Such substances are included in Annex XIV of the Regulation, and may not be placed on the market or used without an authorisation.This authorisation requirement ensures that risks from the use of such substances are either adequately controlled or outweighed by socio-economic benefits. An analysis of alternative substances or technologies will be a fundamental component of the authorisation process. Source: REACH Glossary
autoimmun response is a condition in which the immune system attacks tissues in its own body. This happens if the immune system gets signals telling it that the body tissue is an outside invader. This false signal causes several diseases, such as rheomatoid athritis, lung emphysema, allergies, etc.
The following list gives some of the autoimmune diseases:
Acute disseminated encephalomyelitis (ADEM)
Autoimmune aplastic anemia
Autoimmune lymphoproliferative syndrome
Autoimmune peripheral neuropathy
Autoimmune polyendocrine syndrome
Autoimmune progesterone dermatitis
Autoimmune thrombocytopenic purpura
Balo disease/Balo concentric sclerosis
Chronic inflammatory demyelinating polyneuropathy
Chronic recurrent multifocal osteomyelitis
Chronic obstructive pulmonary disease
Complement component 2 deficiency
Crohn's disease (one of two types of idiopathic inflammatory bowel disease "IBD")
Cutaneous leukocytoclastic angiitis
Diffuse cutaneous systemic sclerosis
Enthesitis-related arthritis[28]
Epidermolysis bullosa acquisita
Erythroblastosis fetalis
Essential mixed cryoglobulinemia
Fibrodysplasia ossificans progressiva
Fibrosing alveolitis (or Idiopathic pulmonary fibrosis)
Guillain-Barré syndrome (GBS)
Herpes gestationis aka Gestational Pemphigoid
Idiopathic inflammatory demyelinating diseases
Idiopathic thrombocytopenic purpura (See Autoimmune thrombocytopenic purpura)
Chronic inflammatory demyelinating polyneuropathy
Juvenile idiopathic arthritis aka Juvenile rheumatoid arthritis
Lambert-Eaton myasthenic syndrome
Linear IgA disease (LAD)
Lou Gehrig's disease (Also Amyotrophic lateral sclerosis)
Lupoid hepatitis aka Autoimmune hepatitis
Miller-Fisher syndrome see Guillain-Barre Syndrome
Mixed connective tissue disease
Mucha-Habermann disease aka Pityriasis lichenoides et varioliformis acuta
Neuromyelitis optica (also Devic's disease)
Occular cicatricial pemphigoid
PANDAS (pediatric autoimmune neuropsychiatric disorders associated with streptococcus)
Paraneoplastic cerebellar degeneration
Paroxysmal nocturnal hemoglobinuria (PNH)
Primary sclerosing cholangitis
Progressive inflammatory neuropathy
Schmidt syndrome another form of APS
Still's disease see Juvenile Rheumatoid Arthritis
Subacute bacterial endocarditis (SBE)
Systemic lupus erythematosis see Lupus erythematosis
Temporal arteritis (also known as "giant cell arteritis")
Ulcerative colitis (one of two types of idiopathic inflammatory bowel disease "IBD")
Undifferentiated connective tissue disease different from Mixed connective tissue disease
Undifferentiated spondyloarthropathy
Source: http://en.wikipedia.org/wiki/Autoimmune_disease
an axiom is a mathematical rule. This basic assumption about a system allows theorems to be developed. For example, the system could be the points and lines in the plane. Then an axiom would be that given any two distinct points in the plane, there is a unique line through them.
an axon (also known as a nerve fiber) is a long, slender projection of a nerve cell (neuron), that typically conducts electrical impulses away from the neuron's cell body.
In certain sensory neurons (pseudounipolar neurons), the impulse travels along an axon from the periphery to the cell body, and from the cell body to the spinal cord along another branch of the same axon. Axon dysfunction causes many inherited and acquired neurological disorders which can affect both the peripheral and central neurons.
an inherited, degenerative disorder of the peripheral and central nervous system or a disorder caused by neurotoxins.