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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