scientistsresearch scientistscience
Other areas of active research include the exploration of matter at the scale of elementary particles as described by high-energy physics, and materials science, which seeks to discover and design new materials. Although there have been remarkable discoveries with regard to brain function and neurotransmitters, the nature of the mind and human thought still remains unknown. The number of scientists is vastly different from country to country. For instance, there are only four full-time scientists per 10,000 workers in India while this number is 79 for the United Kingdom and the United States.

Electricity meter

electric meterelectric meterswatt-hour meter
Thomas Edison at first worked on a direct current (DC) electromechanical meter with a direct reading register, but instead developed an electrochemical metering system, which used an electrolytic cell to totalise current consumption. At periodic intervals the plates were removed and weighed, and the customer billed. The electrochemical meter was labor-intensive to read and not well received by customers. An early type of electrochemical meter used in the United Kingdom was the 'Reason' meter. This consisted of a vertically mounted glass structure with a mercury reservoir at the top of the meter.

William Gilbert (astronomer)

William GilbertGilbert, WilliamGilbert
He invented the first electrical measuring instrument, the electroscope, in the form of a pivoted needle he called the versorium.


The torque arm is connected to the dyno housing and a weighing scale is positioned so that it measures the force exerted by the dyno housing in attempting to rotate. The torque is the force indicated by the scales multiplied by the length of the torque arm measured from the center of the dynamometer. A load cell transducer can be substituted for the scales in order to provide an electrical signal that is proportional to torque. Another means to measure torque is to connect the engine to the dynamo through a torque sensing coupling or torque transducer. A torque transducer provides an electrical signal that is proportional to the torque.


pregnantfirst trimesterpregnant women
The Institute of Medicine recommends an overall pregnancy weight gain for those of normal weight (body mass index of 18.5–24.9), of 11.3–15.9 kg (25–35 pounds) having a singleton pregnancy. Women who are underweight (BMI of less than 18.5), should gain between 12.7–18 kg (28–40 lbs), while those who are overweight (BMI of 25–29.9) are advised to gain between 6.8–11.3 kg (15–25 lbs) and those who are obese (BMI>30) should gain between 5–9 kg (11–20 lbs). These values reference the expectations for a term pregnancy. During pregnancy, insufficient or excessive weight gain can compromise the health of the mother and fetus.


Electrochemical:. pH probes. Electro-galvanic oxygen sensors. Hydrogen sensors. Electromechanical (electromechanical output devices are generically called actuators):. Accelerometers. Air flow sensors. Electroactive polymers. Rotary motors, linear motors. Galvanometers. Linear variable differential transformers or rotary variably differential transformers. Load cells – converts force to mV/V electrical signal using strain gauges. Microelectromechanical systems. Potentiometers (when used for measuring position). Pressure sensors. String potentiometers. Tactile sensors. Vibration powered generators. Vibrating structure gyroscopes. Electroacoustic:.

Outline of physical science

physical sciencesphysical sciencephysical
Instrumental analysis. Electroanalytical method. Wet chemistry. Electrochemistry. Redox reaction. Materials chemistry. The water cycle and the process of transpiration. Freshwater. Oceanography. Weathering and erosion. Rocks. Agrophysics. Soil science. Pedogenesis. Soil fertility. Earth's tectonic structure. Geomorphology and geophysics. Physical geography. Seismology: stress, strain, and earthquakes. Characteristics of mountains and volcanoes. Characteristics and formation of fossils. Atmospheric sciences – the branches of science that study the atmosphere, its processes, the effects other systems have on the atmosphere, and the effects of the atmosphere on these other systems.

Wind tunnel

wind tunnelswind-tunnelwindtunnel
More recently an increasing use of jet-powered, instrumented unmanned vehicles ["research drones"] have replaced some of the traditional uses of wind tunnels. Air is blown or sucked through a duct equipped with a viewing port and instrumentation where models or geometrical shapes are mounted for study. Typically the air is moved through the tunnel using a series of fans. For very large wind tunnels several meters in diameter, a single large fan is not practical, and so instead an array of multiple fans are used in parallel to provide sufficient airflow.

Rechargeable battery

rechargeablerechargeable batteriesstorage batteries
It is composed of one or more electrochemical cells. The term "accumulator" is used as it accumulates and stores energy through a reversible electrochemical reaction. Rechargeable batteries are produced in many different shapes and sizes, ranging from button cells to megawatt systems connected to stabilize an electrical distribution network. Several different combinations of electrode materials and electrolytes are used, including lead–acid, nickel–cadmium (NiCd), nickel–metal hydride (NiMH), lithium-ion (Li-ion), and lithium-ion polymer (Li-ion polymer).

Analytical chemistry

chemical analysisanalytical chemistanalytical
Electrochemical Methods: Fundamentals and Applications. New York: John Wiley & Sons, 2nd Edition, 2000. Bettencourt da Silva, R; Bulska, E; Godlewska-Zylkiewicz, B; Hedrich, M; Majcen, N; Magnusson, B; Marincic, S; Papadakis, I; Patriarca, M; Vassileva, E; Taylor, P; Analytical measurement: measurement uncertainty and statistics, 2012, ISBN: 978-92-79-23070-7.

Chemical potential

chemical driving forceinternal chemical potentialchemical potential,
In electrochemistry, ions do not always tend to go from higher to lower chemical potential, but they do always go from higher to lower electrochemical potential. The electrochemical potential completely characterizes all of the influences on an ion's motion, while the chemical potential includes everything except the electric force. (See below for more on this terminology.)


chemistchemicalChemical Sciences
A reaction is said to be exergonic if the final state is lower on the energy scale than the initial state; in the case of endergonic reactions the situation is the reverse. A reaction is said to be exothermic if the reaction releases heat to the surroundings; in the case of endothermic reactions, the reaction absorbs heat from the surroundings. Chemical reactions are invariably not possible unless the reactants surmount an energy barrier known as the activation energy.

Kibble balance

Kibble (or watt) balance
A Kibble balance (previously watt balance) is an electromechanical measuring instrument that measures the weight of a test object very precisely by the strength of the electric current and voltage needed to produce a compensating force. It is a metrological instrument that can realize the new definition of the kilogram unit of mass based on fundamental constants, termed an electronic or electrical kilogram. The name watt balance came from the fact that the weight of the test mass is proportional to the product of the current and the voltage, which is measured in units of watts.


densedensitiesmass density
The mass is normally measured with a scale or balance; the volume may be measured directly (from the geometry of the object) or by the displacement of a fluid. To determine the density of a liquid or a gas, a hydrometer, a dasymeter or a Coriolis flow meter may be used, respectively. Similarly, hydrostatic weighing uses the displacement of water due to a submerged object to determine the density of the object. If the body is not homogeneous, then its density varies between different regions of the object. In that case the density around any given location is determined by calculating the density of a small volume around that location.

Body adiposity index

adiposity index
The body adiposity index (BAI) is a method of estimating the amount of body fat in humans. The BAI is calculated without using body weight, unlike the body mass index (BMI). Instead, it uses the size of the hips compared to the person's height. Based on population studies, the BAI is approximately equal to the percentage of body fat for adult men and women of differing ethnicities. The BAI is calculated as: Hip circumference (R = 0.602) and height (R = −0.524) are strongly correlated with percentage of body fat.

Reliability (statistics)

For example, if a set of weighing scales consistently measured the weight of an object as 500 grams over the true weight, then the scale would be very reliable, but it would not be valid (as the returned weight is not the true weight). For the scale to be valid, it should return the true weight of an object. This example demonstrates that a perfectly reliable measure is not necessarily valid, but that a valid measure necessarily must be reliable. In practice, testing measures are never perfectly consistent. Theories of test reliability have been developed to estimate the effects of inconsistency on the accuracy of measurement.

Working electrode

redox electrodegold electrodeworking
Electrochemical cell. Electrochemistry. Electrode potential. Electrosynthesis. Reference electrode. Voltammetry.

Saturated calomel electrode

SCEcalomel electrodeHgCl 2
The SCE is used in pH measurement, cyclic voltammetry and general aqueous electrochemistry. This electrode and the silver/silver chloride reference electrode work in the same way. In both electrodes, the activity of the metal ion is fixed by the solubility of the metal salt. The calomel electrode contains mercury, which poses much greater health hazards than the silver metal used in the Ag/AgCl electrode. ja:基準電極#カロメル電極 Cyclic voltammetry. Standard Hydrogen Electrode. Table of standard electrode potentials. Reference electrode.

List of measuring devices

measuring devices
scale || weight | wind vane || wind direction | zymometer || fermentation.


A chloridometer is a measuring instrument used to determine the concentration of chloride ions (Cl – ) in a solution. It uses a process known as coulometric titration or amperostatic coulometry, the accepted electrochemistry reference method to determine the concentration of chloride in biological fluids, including blood serum, blood plasma, urine, sweat, and cerebrospinal fluid. The coulometry process generates silver ions, which react with the chloride to form silver chloride (AgCl). The first chloridometer was designed by a team led by Ernest Cotlove in 1958. Other methods to determine chloride concentration include photometric titration and isotope dilution mass spectrometry.

List of MeSH codes (G07)

. --- body mass index. --- body size. --- body height. --- body weight. --- birth weight. --- fetal weight. --- overweight. --- obesity. --- obesity, morbid. --- thinness. --- body surface area. --- crown-rump length. --- organ size. --- skinfold thickness. --- waist-hip ratio. --- disease susceptibility. --- somatotypes. --- body temperature regulation. --- hibernation. --- sweating. --- thermogenesis. --- shivering. --- skin temperature. --- cell cycle. --- cell division. --- cell nucleus division. --- anaphase. --- chromosome segregation. --- meiosis. --- meiotic prophase i. --- chromosome pairing. --- synaptonemal complex. --- pachytene stage. --- metaphase. --- mitosis. --- anaphase. ---

Childhood obesity

child obesityobesitychild
Childhood obesity is a condition where excess body fat negatively affects a child's health or well-being. As methods to determine body fat directly are difficult, the diagnosis of obesity is often based on BMI. Due to the rising prevalence of obesity in children and its many adverse health effects it is being recognized as a serious public health concern. The term overweight rather than obese is often used when discussing childhood obesity, especially in open discussion, as it is less stigmatizing. Body mass index (BMI) is acceptable for determining obesity for children two years of age and older. It is determined by the ratio of weight to height.

Wii Fit

Wii Fit TrainerWii-fit
Players may undergo "Body Tests," in which the player's body mass index (BMI) is calculated and balance control is tested. Each Body Test determines and updates the player's "Wii Fit Age", which loosely suggests the player's physical strength in relation to his or her true age. A standalone application, called "Wii Fit Channel," may be installed to the Wii Menu in order for players to perform Body Tests without needing to load the Wii Fit game disc. Wii Fit was first revealed as Wii Health Pack by Nintendo's chief game designer Shigeru Miyamoto, during a conference in mid-September 2006.


Withings Wi-Fi body scale
At the 2012 Consumer Electronics Show in January, Withings unveiled the world's first Internet Connected Baby and Toddler Scale, which won a CES Innovations Award. The Smart Kid Scale features two weighing configurations: the first is for weighing infants with a removable baby basket, and the second is the toddler scale that emerges once the baby basket is removed. Parents can access their children's weight readings from any connected device. The Withings Smart Body Analyzer is a smart scale that not only measures weight, but also calculates body mass index and fat mass, registers heart rate and indoor air quality/air temperature, and provides weather reports.