People interested in the research are advised to contact the author for the final version of the publication, or visit the DOI to the publisher's website. • The final author version and the galley proof are versions of the publication after peer review. • The final published version features the final layout of the paper including the volume, issue and page numbers. Link to publication General rights Copyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights. • Users may download and print one copy of any publication from the public portal for the purpose of private study or research. • You may not further distribute the material or use it for any profit-making activity or commercial gain • You may freely distribute the URL identifying the publication in the public portal. 'Can an Ethiopian change his skin, or a leopard its spots? Neither can you do good who are accustomed to doing evil' Jeremiah 13:23 I believe luck is a plot where opportunity meets preparation. In that sense, I'm the luckiest person on earth. If this is to be called a success in any form, and I look taller than yesterday, it is only because I stand on the shoulder of so many great friends, families, and colleagues. I'm so happy that I got to write this part for I have so many people to thank who have helped me all the way through and wouldn't be here, otherwise. First and foremost, praises and thanks to the mother of Jesus Christ, Virgin Mary, for giving me the strength and the showers of blessings throughout my life. My exceptional tribute goes to my Ph.D. supervisors, Professor Joost M.E. Pennings and Andres-Trujillo Barrera. Joost has been supportive and given me the freedom to pursue various projects. He is as passionate and enthusiastic about research and publication as I met him for the first time at Wageningen University in 2011. I hope that I could be as lively, energetic and passionate as you, and to someday be able to command an audience as well as you can. The progress report I must submit every Friday kept me in track [there were times I want to cry so much when I write those reports]. Your 'hello Addy my friend' whenever you pass by my office serves both as a greeting and a reminder of something I have to finish and email it to you; your discontentment with me for not being able to shoot [aim] high and desire to settle for less, reminds me of my father and always motivates me; and your 'does this ring a bell to you, Addy?' reminds me how much more I have to read. I am grateful for the opportunity you gave me. Andres has been a true support, very easy to talk to and gives much attention to the details. Every time I forget to address the comments he made, he has always a very diplomatic way of reminding me not to forget it again [this could happen a dozen times in one project]. I am grateful for your support, sharing yo...