In the manga it shows that Suigetsu had swapped out the DNA samples that were tested when the question of who Sarada's mother was when asked. Although he did it without knowing, Sakura is Sarada's real mother. Karin was the one who delivered Sarada, so it's impossible that Karin is Sarada's biological mother.
Karin kept the umbilical cord as a memento of her help during Sarada's birth. Canonically being the one who offered assistance to Sakura while Sakura was in labor and the one who contributed to Sarada's delivery, Karin was very helpful to the Uchiha family back then.
It's honestly not even wrong, even if you copy a pose from another artist. However if you do take inspiration from something, whether it be a stock image or someone else's piece of art, it's still polite to just credit them, that's all. But it's still nice to credit the original picture and/or artist.
The magnitude of a voltage can be either positive or negative. If the voltage magnitude is positive, the voltage has the same polarity as shown on the diagram. If the voltage magnitude is negative, the voltage polarity is the opposite to that shown on the diagram.
17.2. The bulge test is a method used to determine the material properties of thin films, such as Young's moduli, Poisson's ratios, and residual stresses. As shown in Figure 17.5 , in the bulge test, uniform pressure is applied to one side of a freestanding thin film window, causing it to deflect outwards.