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| In [[physics]], [[engineering]], and [[earth science]]s, '''advection''' is a [[transport]] mechanism of a substance or [[Conservation of energy|conserved]] property by a [[fluid]] due to the fluid's bulk [[Motion (physics)|motion]]. An example of advection is the transport of [[pollutant]]s or [[silt]] in a [[river]] by bulk water flow downstream. Another commonly advected quantity is [[energy]] or [[enthalpy]]. Here the fluid may be any material that contains thermal energy, such as [[water]] or [[air]]. In general, any substance or conserved, [[extensive]] quantity can be advected by a [[fluid]] that can hold or contain the quantity or substance.
| | Msvcr71.dll is an significant file that assists support Windows procedure different components of the program including important files. Specifically, the file is chosen to aid run corresponding files in the "Virtual C Runtime Library". These files are significant in accessing any settings which help the different applications plus programs inside the system. The msvcr71.dll file fulfills various significant functions; yet it's not spared from getting damaged or corrupted. Once the file gets corrupted or damaged, the computer may have a hard time processing plus reading components of the system. Nonetheless, consumers require not panic considering this issue will be solved by following several procedures. And I usually show we several strategies regarding Msvcr71.dll.<br><br>The PC registry starts to get mistakes and fragmented the more we employ the computer because you enter more data each time, and make changes in our systems plus setup. When the registry begins to receive overloaded and full of errors, your computer usually eventually crash. It is possible to fix it on your however, truly dangerous, incredibly when you have no extensive experience in doing this. Therefore, do NOT even attempt to do this yourself.<br><br>When you compare registry cleaners we need a quick acting registry cleaning. It's no superior spending hours and your PC waiting for your registry cleaning to complete its task. We desire your cleaner to complete its task inside minutes.<br><br>Registry cleaners have been designed for 1 purpose - to clean out the 'registry'. This really is the central database which Windows relies on to function. Without this database, Windows wouldn't even exist. It's thus significant, which the computer is constantly adding plus updating the files inside it, even if you're browsing the Internet (like now). This really is awesome, however, the problems occur whenever a few of those files become corrupt or lost. This arises a lot, and it takes a advantageous tool to fix it.<br><br>In a word, to accelerate windows XP, Vista startup, it's very significant to disable several business goods and clean and optimize the registry. You are able to follow the procedures above to disable unwanted programs. To optimize the registry, I suggest you use a [http://bestregistrycleanerfix.com/fix-it-utilities fix it utilities] software. Because it is actually truly risky for you to edit the registry by yourself.<br><br>The most probable cause of the trouble is the system issue - Registry Errors! That is the reason why people that absolutely have over 2 G RAM on their computers are nonetheless continually bothered by the problem.<br><br>Another problem with the damaged variation is that it takes too much time to scan the system and whilst it happens to be scanning, you cannot utilize the computer otherwise. Moreover, there is no technical help to these cracked versions that means when you get stuck someplace, we can't ask for aid. They even do not have any customer service aid lines wherein you will call or send to solve the issues.<br><br>What I would suggest is to look on the own for registry products. You can do this with a Google look. If you find goods, look for reviews and reviews regarding the product. Then you can see how others like the product, plus how effectively it works. |
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| In advection, a fluid transports some conserved quantity or material via bulk motion. The fluid's motion is described [[Mathematics|mathematically]] as a [[vector field]], and the transported material is described by a [[scalar field]] showing its distribution over space. Advection requires currents in the fluid, and so cannot happen in rigid solids. It does not include transport of substances by [[molecular diffusion]].
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| Advection is sometimes confused with the more encompassing process of [[convection]] which is the combination of advective transport and diffusive transport.
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| In [[meteorology]] and [[physical oceanography]], advection often refers to the transport of some property of the atmosphere or [[ocean]], such as [[heat]], humidity (see [[water vapor|moisture]]) or salinity.
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| <!-- This is sentence is patently false, e.g. cloud formation is vertical advection of water vapor driven by density gradients! See, for example, the following sentence:
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| Meteorological or oceanographic advective transport is perpendicular to isobaric surfaces and is therefore predominantly [[Horizontal plane|horizontal]].
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| -->
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| Advection is important for the formation of [[orographic]] clouds and the precipitation of water from clouds, as part of the [[hydrological cycle]].
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| ==Distinction between advection and convection==
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| The term ''advection'' sometimes serves as a synonym for ''[[convection]]'', but technically, ''convection'' covers the sum of transport both by [[diffusion]] and by advection. Advective transport describes the movement of some quantity via the bulk flow of a fluid (as in a river or pipeline).<ref>Suthan S. Suthersan, "Remediation engineering: design concepts", CRC Press, 1996. [http://books.google.ca/books?id=Rd2QIcNKl1UC&pg=PA13&dq=advection+and+convection#v=onepage&q=advection%20and%20convection&f=false (Google books)]
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| </ref><ref> | |
| Jacques Willy Delleur, "The handbook of groundwater engineering", CRC Press, 2006. [http://books.google.ca/books?id=EiXxaGH3CzcC&pg=PT485&dq=advection+versus+convection#v=onepage&q=advection%20versus%20convection&f=false (Google books)]
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| </ref>
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| <!--
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| An example of convection is flow over a hot plate or below a chilled water surface in a lake. In the ocean and atmospheric sciences, advection is understood as horizontal movement resulting in transport "from place to place", while convection is vertical "mixing". <ref>David A. Randall, "General circulation model development", Academic Press, 2000. [http://books.google.ca/books?id=pRibtFBDNDAC&pg=PA648&dq=advection+and+convection#v=onepage&q=advection%20and%20convection&f=false (Google books)]</ref><ref>Scott Ryan, "Earth Science (CliffsQuickReview)", Wiley Publishing Inc., 2006. [http://books.google.com/books?id=PV_BabxTTkcC&pg=PA99&dq=advection+convection&lr=&as_drrb_is=q&as_minm_is=0&as_miny_is=&as_maxm_is=0&as_maxy_is=&as_brr=0#v=onepage&q=advection%20convection&f=false (Google books)]</ref> Another view is that advection occurs with fluid transport of a point, while convection may be considered as fluid transport of a vector.
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| ==Meteorology==
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| In [[meteorology]] and [[physical oceanography]], advection often refers to the transport of some property of the atmosphere or [[ocean]], such as [[heat]], humidity or salinity. Advection is important for the formation of [[orographic cloud]]s and the precipitation of water from clouds, as part of the [[hydrological cycle]].
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| == Other quantities ==
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| The advection equation also applies if the quantity being advected is represented by a [[probability density function]] at each point, although accounting for diffusion is more difficult.{{fact|date=April 2013}}
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| ==Mathematics of advection==
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| The '''advection equation''' is the [[partial differential equation]] that governs the motion of a conserved [[scalar field]] as it is advected by a known [[velocity field|velocity vector field]]. It is derived using the scalar field's [[conservation law]], together with [[Gauss's theorem]], and taking the [[infinitesimal]] limit.
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| One easily-visualized example of advection is the transport of ink dumped into a river. As the river flows, ink will move downstream in a "pulse" via advection, as the water's movement itself transports the ink. If added to a lake without significant bulk water flow, the ink would simply disperse outwards from its source in a [[Diffusion|diffusive]] manner, which is not advection. Note that as it moves downstream, the "pulse" of ink will also spread via diffusion. The sum of these processes is called [[convection]].
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| ===The advection equation===
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| In Cartesian coordinates the advection [[Operator (mathematics)|operator]] is
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| :<math>\mathbf{u} \cdot \nabla = u_x \frac{\partial}{\partial x} + u_y \frac{\partial}{\partial y} + u_z \frac{\partial}{\partial z}</math>.
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| where '''u''' = (''u<sub>x</sub>, u<sub>y</sub>, u<sub>z</sub>'') is the [[velocity field]], and ∇ is the [[del]] operator (note that [[Cartesian coordinate system|Cartesian coordinates]] are used here).
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| The advection equation for a conserved quantity described by a [[scalar field]] ''ψ'' is expressed mathematically by a [[continuity equation]]:
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| {{Equation box 1
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| |indent =:
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| |equation = <math> \frac{\partial\psi}{\partial t} +\nabla\cdot\left( \psi{\bold u}\right) =0 </math>
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| |cellpadding
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| |border
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| |border colour = #50C878
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| |background colour = #ECFCF4}}
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| where ∇∙ is the [[divergence]] operator and again '''u''' is the [[velocity field|velocity vector field]]. Frequently, it is assumed that the flow is [[incompressible flow|incompressible]], that is, the [[velocity field]] satisfies
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| :<math>\nabla\cdot{\bold u}=0</math>
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| and '''u''' is said to be [[solenoidal]]. If this is so, the above equation can be rewritten as
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| :{{Equation box 1
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| |equation=<math> \frac{\partial\psi}{\partial t} +{\bold u}\cdot\nabla\psi=0. </math>
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| |indent=:
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| |cellpadding
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| |border
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| |border colour = #0073CF
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| |background colour=#F5FFFA}}
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| In particular, if the flow is steady, then
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| :<math>{\bold u}\cdot\nabla\psi=0</math>
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| which shows that ''ψ'' is constant along a [[Streamlines, streaklines and pathlines|streamline]]. Hence, <math> \partial\psi/\partial t=0,</math> so ''ψ'' doesn't vary in time.
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| If a vector quantity '''a''' (such as a [[magnetic field]]) is being advected by the [[solenoidal]] [[velocity field]] '''u''', the advection equation above becomes:
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| :<math> \frac{\partial{\bold a}}{\partial t} + \left( {\bold u} \cdot \nabla \right) {\bold a} =0. </math>
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| Here, '''a''' is a [[vector field]] instead of the [[scalar field]] ''ψ''.
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| ===Solving the equation===
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| The advection equation is not simple to solve [[numerical analysis|numerically]]: the system is a [[hyperbolic partial differential equation]], and interest typically centers on [[Continuous function|discontinuous]] "shock" solutions (which are notoriously difficult for numerical schemes to handle).
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| Even with one space dimension and a constant [[velocity field]], the system remains difficult to simulate. The equation becomes
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| :<math> \frac{\partial\psi}{\partial t}+u_x \frac{\partial\psi}{\partial x}=0 </math>
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| where ''ψ'' = ''ψ''(''x'', ''t'') is the [[scalar field]] being advected and ''u<sub>x</sub>'' is the ''x'' component of the vector '''u''' = (''u<sub>x</sub>'',0,0).
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| According to Zang,<ref>{{cite journal
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| | last = Zang
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| | first = Thomas
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| | year = 1991
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| | title = On the rotation and skew-symmetric forms for incompressible flow simulations
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| | journal = Applied Numerical Mathematics
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| | volume = 7
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| | pages = 27–40
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| | doi = 10.1016/0168-9274(91)90102-6
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| }}</ref> numerical simulation can be aided by considering the [[Skew-symmetric matrix|skew symmetric]] form for the advection operator.
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| :<math> \frac{1}{2} {\bold u} \cdot \nabla {\bold u} + \frac{1}{2} \nabla ({\bold u} {\bold u}) </math>
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| where
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| :<math> \nabla ({\bold u} {\bold u}) = [\nabla ({\bold u} u_x),\nabla ({\bold u} u_y),\nabla ({\bold u} u_z)]</math>
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| and '''u''' is the same as above.
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| Since skew symmetry implies only [[Imaginary number|imaginary]] [[eigenvalues]], this form reduces the "blow up" and "spectral blocking" often experienced in numerical solutions with sharp discontinuities (see Boyd<ref>{{cite book |last=Boyd
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| |first=John P. |title= Chebyshev and Fourier Spectral Methods 2nd edition |url= http://www-personal.engin.umich.edu/~jpboyd/BOOK_Spectral2000.html |year=2000 |publisher=Dover |location= |isbn= |pages=213}}</ref>).
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| Using [[vector calculus identities#Vector dot product|vector calculus identities]], these operators can also be expressed in other ways, available in more software packages for more coordinate systems.
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| :<math>\mathbf{u} \cdot \nabla \mathbf{u} = \nabla \left( \frac{\|\mathbf{u}\|^2}{2} \right) + \left( \nabla \times \mathbf{u} \right) \times \mathbf{u}</math>
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| :<math> \frac{1}{2} \mathbf{u} \cdot \nabla \mathbf{u} + \frac{1}{2} \nabla (\mathbf{u} \mathbf{u}) = \nabla \left( \frac{\|\mathbf{u}\|^2}{2} \right) + \left( \nabla \times \mathbf{u} \right) \times \mathbf{u} + \frac{1}{2} \mathbf{u} (\nabla \cdot \mathbf{u}) </math>
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| This form also makes visible that the [[Skew-symmetric matrix|skew symmetric]] operator introduces error when the velocity field diverges. Solving the advection equation by numerical methods is very challenging and there is a large scientific literature about this.
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| == See also ==
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| * [[Continuity equation]]
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| * [[Convection]]
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| * [[Courant number]]
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| * [[Péclet number]]
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| * [[Overshoot (signal)]]
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| * [[Partial differential equation]]
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| * [[Del]]
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| * [[Earth's atmosphere]]
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| * [[Diffusion]]
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| ==References==
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| <!--See [[Wikipedia:Footnotes]] for an explanation of how to generate footnotes using the <ref(erences/)> tags-->
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| <references/>
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| [[Category:Vector calculus]]
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| [[Category:Atmospheric dynamics]]
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| [[Category:Hyperbolic partial differential equations]]
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| [[Category:Equations of fluid dynamics]]
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| [[Category:Oceanography]]
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| [[Category:Convection]]
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| [[Category:Heat transfer]]
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| [[Category:Transport phenomena]]
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Msvcr71.dll is an significant file that assists support Windows procedure different components of the program including important files. Specifically, the file is chosen to aid run corresponding files in the "Virtual C Runtime Library". These files are significant in accessing any settings which help the different applications plus programs inside the system. The msvcr71.dll file fulfills various significant functions; yet it's not spared from getting damaged or corrupted. Once the file gets corrupted or damaged, the computer may have a hard time processing plus reading components of the system. Nonetheless, consumers require not panic considering this issue will be solved by following several procedures. And I usually show we several strategies regarding Msvcr71.dll.
The PC registry starts to get mistakes and fragmented the more we employ the computer because you enter more data each time, and make changes in our systems plus setup. When the registry begins to receive overloaded and full of errors, your computer usually eventually crash. It is possible to fix it on your however, truly dangerous, incredibly when you have no extensive experience in doing this. Therefore, do NOT even attempt to do this yourself.
When you compare registry cleaners we need a quick acting registry cleaning. It's no superior spending hours and your PC waiting for your registry cleaning to complete its task. We desire your cleaner to complete its task inside minutes.
Registry cleaners have been designed for 1 purpose - to clean out the 'registry'. This really is the central database which Windows relies on to function. Without this database, Windows wouldn't even exist. It's thus significant, which the computer is constantly adding plus updating the files inside it, even if you're browsing the Internet (like now). This really is awesome, however, the problems occur whenever a few of those files become corrupt or lost. This arises a lot, and it takes a advantageous tool to fix it.
In a word, to accelerate windows XP, Vista startup, it's very significant to disable several business goods and clean and optimize the registry. You are able to follow the procedures above to disable unwanted programs. To optimize the registry, I suggest you use a fix it utilities software. Because it is actually truly risky for you to edit the registry by yourself.
The most probable cause of the trouble is the system issue - Registry Errors! That is the reason why people that absolutely have over 2 G RAM on their computers are nonetheless continually bothered by the problem.
Another problem with the damaged variation is that it takes too much time to scan the system and whilst it happens to be scanning, you cannot utilize the computer otherwise. Moreover, there is no technical help to these cracked versions that means when you get stuck someplace, we can't ask for aid. They even do not have any customer service aid lines wherein you will call or send to solve the issues.
What I would suggest is to look on the own for registry products. You can do this with a Google look. If you find goods, look for reviews and reviews regarding the product. Then you can see how others like the product, plus how effectively it works.