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  1. Kt/V - Wikipedia

    en.wikipedia.org/wiki/Kt/V
    • Rationale For Kt/V as A Marker of Dialysis Adequacy
    • Relation to Urr
    • Peritoneal Dialysis
    • Reason For Adoption
    • Criticisms/Disadvantages of Kt/V
    • External Links

    K (clearance) multiplied by t (time) is a volume (since mL/min × min = mL, or L/h × h = L), and (K × t) can be thought of as the mL or L of fluid (blood in this case) cleared of urea (or any other solute) during the course of a single treatment. V also is a volume, expressed in mL or L. So the ratio of K × t / Vis a so-called "dimensionless ratio" and can be thought of as a multiple of the volume of plasma cleared of urea divided by the distribution volume of urea. When Kt/V = 1.0, a volume of blood equal to the distribution volume of urea has been completely cleared of urea. The relationship between Kt/V and the concentration of urea C at the end of dialysis can be derived from the first-order differential equation that describes exponential decayand models the clearance of any substance from the body where the concentration of that substance decreases in an exponential fashion: where 1. C is the concentration [mol/m3] 2. tis the time [s] 3. K is the clearance [m3/s] 4. V is the vo...

    The URR or Urea reduction ratio is simply the fractional reduction of urea during dialysis. So by definition, URR = 1 − C/C0. So 1−URR = C/C0. So by algebra, substituting into equation (4) above, since ln C/C0 = − ln C0/C, we get:

    Kt/V (in the context of peritoneal dialysis) was developed by Michael J. Lysaghtin a series of articles on peritoneal dialysis. The steady-state solution of a simplified mass transfer equation that is used to describe the mass exchange over a semi-permeable membrane and models peritoneal dialysisis where 1. CB is the concentration in the blood [ mol/m3] 2. KD is the clearance [ m3/s ] 3. m ˙ {\\displaystyle {\\dot {m}}} is the urea mass generation [ mol/s ] This can also be written as: The mass generation (of urea), in steady state, can be expressed as the mass (of urea) in the effluent per time: where 1. CE is the concentration of urea in effluent [ mol/m3] 2. VE is the volume of effluent [ m3] 3. tis the time [ s ] Lysaght, motivated by equations 6b and 6c, defined the value KD: Lysaght uses "ml/min" for the clearance. In order to convert the above clearance (which is in m3/s) to ml/min one has to multiply by 60 × 1000 × 1000. Once KD is defined the following equation is used to cal...

    Kt/V has been widely adopted because it was correlated with survival. Before Kt/V nephrologists measured the serum urea concentration (specifically thetime-averaged concentration of urea (TAC of urea)), which was found not to be correlated with survival (due to its strong dependence on proteinintake) and thus deemed an unreliable marker of dialysis adequacy.

    It is complex and tedious to calculate. Many nephrologists have difficulty understanding it.
    Kt/V only measures a change in the concentration of urea and implicitly assumes the clearance of urea is comparable to other toxins. (It ignores molecules larger than urea having diffusion-limited...
    Kt/V does not take into account the role of ultrafiltration.

    Hemodialysis

    1. Hemodialysis Dose and Adequacy– a description of URR and Kt/V from the Kidney and Urologic Diseases Clearinghouse. 2. Kt/V and the adequacy of hemodialysis– UpToDate.com

    Peritoneal dialysis

    1. Advisory on Peritoneal Dialysis– American Association of Kidney Patients 2. Peritoneal Dialysis Dose and Adequacy– a description of URR and Kt/V from the Kidney and Urologic Diseases Clearinghouse.

    Calculators

    1. spKt/V,eKt/V,URR,nPCR,GNRI etc. dialysis calculation– hdtool.net. 2. free Kt/V calculators, single pool and equilibrated HD, PD, no login needed, site used by dozens of dialysis centers around the world for over 10 years– kt-v.net 3. Web/javascript program that does formal 2-pool urea kinetics in multiple patients– ureakinetics.org 4. Kt/V calculator– medindia.com 5. Kt/V– HDCN

  2. Electric generator - Wikipedia

    en.wikipedia.org/wiki/Electric_generator
    • Terminology
    • History
    • Specialized Types of Generator
    • Common Use Cases
    • Equivalent Circuit

    Electromagneticgenerators fall into one of two broad categories, dynamos and alternators. 1. Dynamos generate pulsing direct current through the use of a commutator. 2. Alternators generate alternating current. Mechanically a generator consists of a rotating part and a stationary part: 1. Rotor: The rotating part of an electrical machine. 2. Stator: The stationary part of an electrical machine, which surrounds the rotor. One of these parts generates a magnetic field, the other has a wire winding in which the changing field induces an electric current: 1. Field winding or field (permanent) magnets: The magnetic field-producing component of an electrical machine. The magnetic field of the dynamo or alternator can be provided by either wire windings called field coils or permanent magnets. Electrically-excited generators include an excitation system to produce the field flux. A generator using permanent magnets (PMs) is sometimes called a magneto, or a permanent magnet synchronous gene...

    Before the connection between magnetism and electricity was discovered, electrostatic generators were invented. They operated on electrostatic principles, by using moving electrically charged belts, plates, and disks that carried charge to a high potential electrode. The charge was generated using either of two mechanisms: electrostatic induction or the triboelectric effect. Such generators generated very high voltage and low current. Because of their inefficiency and the difficulty of insulating machines that produced very high voltages, electrostatic generators had low power ratings, and were never used for generation of commercially significant quantities of electric power. Their only practical applications were to power early X-ray tubes, and later in some atomic particle accelerators.

    Direct current

    A dynamo uses commutators to produce direct current. It is self-excited, i.e. its field electromagnets are powered by the machine's own output. Other types of DC generators use a separate source of direct current to energize their field magnets.

    Power station

    A power station, also referred to as a power plant or powerhouse and sometimes generating station or generating plant, is an industrial facility for the generation of electric power. Most power stations contain one or more generators, a rotating machine that converts mechanical power into three-phase electric power. The relative motion between a magnetic field and a conductor creates an electrical current. The energy source harnessed to turn the generator varies widely. Most power stations in...

    Genset

    An engine-generator is the combination of an electrical generator and an engine (prime mover) mounted together to form a single piece of self-contained equipment. The engines used are usually piston engines, but gas turbines can also be used, and there are even hybrid diesel-gas units, called dual-fuel units. Many different versions of engine-generators are available - ranging from very small portable petrolpowered sets to large turbine installations. The primary advantage of engine-generator...

    Human powered electrical generators

    A generator can also be driven by human muscle power (for instance, in field radio station equipment). Human powered electric generators are commercially available, and have been the project of some DIY enthusiasts. Typically operated by means of pedal power, a converted bicycle trainer, or a foot pump, such generators can be practically used to charge batteries, and in some cases are designed with an integral inverter. An average "healthy human" can produce a steady 75 Watts (0.1 horsepower)...

    An equivalent circuit of a generator and load is shown in the adjacent diagram. The generator is represented by an abstract generator consisting of an ideal voltage source and an internal impedance. The generator's V G {\\displaystyle V_{\\text{G}}} and R G {\\displaystyle R_{\\text{G}}} parameters can be determined by measuring the winding resistance (corrected to operating temperature), and measuring the open-circuit and loaded voltage for a defined current load. This is the simplest model of a generator, further elements may need to be added for an accurate representation. In particular, inductance can be added to allow for the machine's windings and magnetic leakage flux,but a full representation can become much more complex than this.

  3. SWOT analysis - Wikipedia

    en.wikipedia.org/wiki/SWOT_analysis
    • Overview
    • Use
    • in Community Organizations
    • Limitations and Alternatives
    • SWOT Analysis in Popular Culture
    • Bibliography

    SWOT assumes that strengths and weaknesses are frequently internal, while opportunities and threats are more commonly external.The name is an acronym for the four parameters the technique examines: 1. Strengths: characteristics of the business or project that give it an advantage over others. 2. Weaknesses: characteristics that place the business or project at a disadvantage relative to others. 3. Opportunities: elements in the environment that the business or project could exploit to its advantage. 4. Threats: elements in the environment that could cause trouble for the business or project. The degree to which the internal environment of the firm matches with the external environment is expressed by the concept of strategic fit. Identification of SWOTs is important because they can inform later steps in planning to achieve the objective. First, decision-makers should consider whether the objective is attainable, given the SWOTs. If the objective is notattainable, they must select a...

    SWOT analysis can be used in any decision-making situation when a desired end-state (objective) is defined, not just profit-seeking organizations. Examples include non-profit organizations, governmental units, and individuals. SWOT analysis may also be used in pre-crisis planning and preventive crisis management. SWOT analysis may also be used in creating a recommendation during a viability study/survey.

    The SWOT analysis has been used in community work as a tool to identify positive and negative factors within organizations, communities, and the broader society that promote or inhibit successful implementation of social services and social change efforts.It is used as a preliminary resource, assessing strengths, weaknesses, opportunities, and threats in a community served by a nonprofit or community organization. Although SWOT analysis is a part of the planning, it will not provide a strategic plan if used by itself, but a SWOT list can becomes a series of recommendations. Strengths and weaknesses (internal factors within an organization): 1. Human resources—staff, volunteers, board members, target population 2. Physical resources—your location, building, equipment 3. Financial—grants, funding agencies, other sources of income 4. Activities and processes—programs you run, systems you employ 5. Past experiences—building blocks for learning and success, your reputation in the communi...

    SWOT is intended as a starting point for discussion and cannot, in itself, show managers how to achieve a competitive advantage,particularly in a rapidly changing environment. Menon et al. (1999) and Hill and Westbrook (1997) suggested "no-one subsequently used the outputs within the later stages of the strategy". Others have critiqued hastily designed SWOT lists. Preoccupation with a single strength, such as cost control, they can neglect their weaknesses, such as product quality.Domineering by one or two community workers devalues the possible contributions of community members. Michael Porter developed the five forces framework as a reaction to SWOT, which he found lacking in rigor and ad hoc. Other names include WOTS-UP (Gray and Smeltzer, 1989) and TOWS(reversing the emphasis, with external first).

    Ads: Coca-Cola has used SWOT analysisin targeting television ads
    Television shows: In the Silicon Valley episode "Homicide" (Season 2, Episode 6), Jared Dunn (Zach Woods) introduces the Pied Piper team to SWOT analysis. Later in that episode Dinesh (Kumail Nanji...

    Dag Øivind Madsen, "SWOT Analysis: A Management Fashion Perspective", International Journal of Business Research 16:1:39–56 (2016) full text

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