HOW TO SET UP , CONDUCT AND REPORT A SCIENTIFIC STUDY
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Table 1c . Coherent derived units in the SI with special names and symbol .
Derived quantity
plane angle solid angle frequency force pressure , stress energy , work , amount of heat power , radiant flux electric charge , amount of electricity electric potential diference , ( e ) electromotive force capacitance electric rezistance electric conductance magnetic flux magnetic flux density inductance Celsius temperature luminous flux illuminance activity reffered to a radionuclide ( g ) absorbded dose , specific energy ( imparted ), kerma dose equivalent , ambient dose equivalent , directional dose equivalent , personal dose equivalent catalytic activity
SI coherent derived unit ( a )
Name radian ( b ) steradian ( b ) hertz ( d ) newton pascal joule watt coulomb
volt
farad ohm siemens weber tesla henry degree Celsius ( f ) lumen lux becquerel ( d )
gray sievert ( h )
katal
Symbol
( a ) The SI prefixes may be used with any of the special names and symbols , but when this is done the resulting unit will no longer be coherent . ( b ) The radian and steradian are special names for the number one that may be used to convey information about the quantity concerned . In practice the symbols rad and sr are used where appropiate , but the symbol for the derived unit one is generally omitted in specifying the values of dimensionless quantities . ( c ) In photometry the name steradian and the symbol sr are usually retained in expressions for units ( d ) The hertz is used only for periodic phenomena , and the becquerel is used only for stochastic processes in activity reffered to a radionuclide . ( e ) Editors ' note : Electric potential difference is also called " voltage " in the United States and in many other countries , as well as " electric tension " or simply " tension " in some countires . ( f ) The degree Celsius is the special name for the kelvin used to express Celsius temperatures . The degree Celsius and the kelvin are equal in size , so that the numerical value of a temperature difference or temperature interval is the same when expressed in either degrees Celsius or in kelvins . ( g ) Activity referred to a radionuclide is sometimes incorrectly called radioactivity . ( h ) See CIPM Recommendation 2 ( CI-2002 ), p . 78 , on the use of sievert ( PV , 2002 , 70 , 205 ).
rad sr ( c )
Hz N Pa J W C
V
F W S Wb T H º C lm lx Bq
Gy Sv
kat
Expressed in terms of other SI units
1 ( b )
1 ( b )
N / m2 Nm J / s
W / A
C / V V / A A / V Vs Wb / m 2 Wb / A
cd sr ( c ) lm / m 2
J / kg J / kg
Expressed in terms of SI base units
m / m m 2 / m 2 s -1 m kg s -2 m -1 kg s -2
m 2 kg s -3 s A
m 2 kg s -3 A -1
m -2 kg -1 s 4 A 2 m 2 kg s -3 A -2 m -2 kg -1 s 3 A 2 m 2 kg s -2 A -1 kg s -2 A -1 m 2 kg s -2 A -2 K cd m -2 cd s -1
m 2 s -2 m 2 s -2
s -1 mol contain information about the statistical analysis , the minimum being the p value and showing where the significant differences are . The “ Discussion ” is the only place , where interpretations , explanations and maybe speculations are allowed . Very often discussions are difficult to follow because the reader is not as familiar with the topic as the authors and , on top of it all , there is a lack of structure . It is recommended to discuss first “ Materials & Methods ”: Why were the materials used , why was the used method selected and which are its advantages / disadvantages or limitations . Compare your method with methods of other investigations etc . Only then in a second subchapter must the results be discussed : Here the null hypothesis can be accepted or rejected based on the results . Give reasons for the outcome , explain why significant differences were found or not , compare your data with the outcome of other studies and explain why there are differences , if indicated . If possible give explanations about the possible impact to clinical dentistry of the results and finally , it is helpful if indications about further research based on the results of the present study is given . Having said all of the above , one must be careful in the formulation . It should be very clear which are facts from the study or other studies , which are interpretations of these facts and which are hypotheses one could come up based on the findings . At the end of the “ Discussion ” conclusions should be drawn . They must be strictly limited to the facts of the findings in the present study and should be formulated as briefly as possible ( e . g . “ the in vitro wear volume of the glass ionomer tested was more than 2x the wear volume of the universal
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