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The | '''Haber's rule''' or '''Haber's law''' is a [[mathematical]] statement of the relationship between the [[concentration]] of a [[poisonous]] [[gas]] and how long the gas must be breathed to produce death, or other [[toxic]] effect. The rule was formulated by [[Germany|German]] [[chemist]] [[Fritz Haber]] in the early 1900s. | ||
Haber's rule states that, for a given poisonous gas, <math>C\times t = k</math>, where <math>C</math> is the concentration of the gas (mass per unit volume), <math>t</math> is the amount of time necessary to breathe the gas, in order to produce a given toxic effect, and <math>k</math> is a constant, depending on both the gas and the effect. Thus, the rule states that doubling the concentration will halve the time, for example. | |||
It makes [[Equivalent (chemistry)|equivalent]] any two groupings of [[dose concentration]] and [[exposure time]] that have equivalent [[mathematical product]]s. For instance, if we assign [[Dose (biochemistry)|dose]] [[concentration]] the [[symbol]] C, and [[time]] the classic t, then for any two dose [[Conceptual model|schema]], if C<sub>1</sub>t<sub>1</sub>=C<sub>2</sub>t<sub>2</sub>, then under Haber's rule the two dose schema are equivalent. | |||
Haber's rule is an approximation, useful with certain inhaled poisons under certain conditions, and Haber himself acknowledged that it was not always applicable. If a substance is efficiently eliminated in the host, for example, then Haber's Law breaks down in the limit of t approaching the [[Order of reaction|order]] of the [[half-life]] of the [[drug]], rewriting the equation as the integral ∫Cdt = constant for arbitrary varying C and elapsed time T. It is very convenient, however, because its relationship between <math>C</math> and <math>t</math> appears as a straight line in a [[log-log plot]]. | |||
In 1940, [[statistician]] C. I. Bliss published a study of [[toxicity]] in [[insecticide]]s in which he proposed more complex [[mathematical model|models]], for example, expressing the relationship between <math>C</math> and <math>t</math> as two straight line segments in a [[log-log plot]].<ref>{{cite journal | author=C. I. Bliss | title= The relationship between exposure, time, concentration and toxicity in experiments on insecticides | journal=Annals of the Entomological Society of America | year=1940 | volume=33 | pages=721–766}}</ref> However, because of its simplicity, Haber's rule continued to be widely used. Recently, some researchers have argued that it is time to move beyond the simple relationship expressed by Haber's rule and to make regular use of more sophisticated models.<ref>{{cite journal | author=F. J. Miller, P. M. Schlosser, and D. B. Janszen | title=Haber's rule: a special case in a family of curves relating concentration and duration of exposure to a fixed level of response for a given endpoint | journal=Toxicology | date=August 14, 2000 | volume=149| issue = 1 | pages=22–34 | pmid=10963858 | doi=10.1016/S0300-483X(00)00229-8}}</ref> | |||
==See also== | |||
*{{LD50}} | |||
*[[Fritz Haber]] | |||
*[[Toxicology]] | |||
*[[Chemical warfare]] | |||
*[[Area under the curve]] | |||
==References== | |||
{{reflist}} | |||
[[Category:Pharmacokinetics]] | |||
[[Category:Toxicology]] |
Revision as of 16:33, 20 April 2013
Haber's rule or Haber's law is a mathematical statement of the relationship between the concentration of a poisonous gas and how long the gas must be breathed to produce death, or other toxic effect. The rule was formulated by German chemist Fritz Haber in the early 1900s.
Haber's rule states that, for a given poisonous gas, , where is the concentration of the gas (mass per unit volume), is the amount of time necessary to breathe the gas, in order to produce a given toxic effect, and is a constant, depending on both the gas and the effect. Thus, the rule states that doubling the concentration will halve the time, for example.
It makes equivalent any two groupings of dose concentration and exposure time that have equivalent mathematical products. For instance, if we assign dose concentration the symbol C, and time the classic t, then for any two dose schema, if C1t1=C2t2, then under Haber's rule the two dose schema are equivalent.
Haber's rule is an approximation, useful with certain inhaled poisons under certain conditions, and Haber himself acknowledged that it was not always applicable. If a substance is efficiently eliminated in the host, for example, then Haber's Law breaks down in the limit of t approaching the order of the half-life of the drug, rewriting the equation as the integral ∫Cdt = constant for arbitrary varying C and elapsed time T. It is very convenient, however, because its relationship between and appears as a straight line in a log-log plot.
In 1940, statistician C. I. Bliss published a study of toxicity in insecticides in which he proposed more complex models, for example, expressing the relationship between and as two straight line segments in a log-log plot.[1] However, because of its simplicity, Haber's rule continued to be widely used. Recently, some researchers have argued that it is time to move beyond the simple relationship expressed by Haber's rule and to make regular use of more sophisticated models.[2]
See also
References
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In its statement, the singapore property listing - website link, government claimed that the majority citizens buying their first residence won't be hurt by the new measures. Some concessions can even be prolonged to chose teams of consumers, similar to married couples with a minimum of one Singaporean partner who are purchasing their second property so long as they intend to promote their first residential property. Lower the LTV limit on housing loans granted by monetary establishments regulated by MAS from 70% to 60% for property purchasers who are individuals with a number of outstanding housing loans on the time of the brand new housing purchase. Singapore Property Measures - 30 August 2010 The most popular seek for the number of bedrooms in Singapore is 4, followed by 2 and three. Lush Acres EC @ Sengkang
Discover out more about real estate funding in the area, together with info on international funding incentives and property possession. Many Singaporeans have been investing in property across the causeway in recent years, attracted by comparatively low prices. However, those who need to exit their investments quickly are likely to face significant challenges when trying to sell their property – and could finally be stuck with a property they can't sell. Career improvement programmes, in-house valuation, auctions and administrative help, venture advertising and marketing, skilled talks and traisning are continuously planned for the sales associates to help them obtain better outcomes for his or her shoppers while at Knight Frank Singapore. No change Present Rules
Extending the tax exemption would help. The exemption, which may be as a lot as $2 million per family, covers individuals who negotiate a principal reduction on their existing mortgage, sell their house short (i.e., for lower than the excellent loans), or take part in a foreclosure course of. An extension of theexemption would seem like a common-sense means to assist stabilize the housing market, but the political turmoil around the fiscal-cliff negotiations means widespread sense could not win out. Home Minority Chief Nancy Pelosi (D-Calif.) believes that the mortgage relief provision will be on the table during the grand-cut price talks, in response to communications director Nadeam Elshami. Buying or promoting of blue mild bulbs is unlawful.
A vendor's stamp duty has been launched on industrial property for the primary time, at rates ranging from 5 per cent to 15 per cent. The Authorities might be trying to reassure the market that they aren't in opposition to foreigners and PRs investing in Singapore's property market. They imposed these measures because of extenuating components available in the market." The sale of new dual-key EC models will even be restricted to multi-generational households only. The models have two separate entrances, permitting grandparents, for example, to dwell separately. The vendor's stamp obligation takes effect right this moment and applies to industrial property and plots which might be offered inside three years of the date of buy. JLL named Best Performing Property Brand for second year running
The data offered is for normal info purposes only and isn't supposed to be personalised investment or monetary advice. Motley Fool Singapore contributor Stanley Lim would not personal shares in any corporations talked about. Singapore private home costs increased by 1.eight% within the fourth quarter of 2012, up from 0.6% within the earlier quarter. Resale prices of government-built HDB residences which are usually bought by Singaporeans, elevated by 2.5%, quarter on quarter, the quickest acquire in five quarters. And industrial property, prices are actually double the levels of three years ago. No withholding tax in the event you sell your property. All your local information regarding vital HDB policies, condominium launches, land growth, commercial property and more
There are various methods to go about discovering the precise property. Some local newspapers (together with the Straits Instances ) have categorised property sections and many local property brokers have websites. Now there are some specifics to consider when buying a 'new launch' rental. Intended use of the unit Every sale begins with 10 p.c low cost for finish of season sale; changes to 20 % discount storewide; follows by additional reduction of fiftyand ends with last discount of 70 % or extra. Typically there is even a warehouse sale or transferring out sale with huge mark-down of costs for stock clearance. Deborah Regulation from Expat Realtor shares her property market update, plus prime rental residences and houses at the moment available to lease Esparina EC @ Sengkang