Acknowledgement to Reviewers of Challenges in 2019

The editorial team greatly appreciates the reviewers who have dedicated their considerable time and expertise to the journal’s rigorous editorial process over the past 12 months, regardless of whether the papers are finally published or not. In 2019, a total of 31 papers were published in the journal, with a median time to first decision of 24 days and a median time from submission to publication of 42 days. The editors would like to express their sincere gratitude to the following reviewers for their generous contribution in 2019:

Ahmadvand, Seyedsaeid	Kjellen, Marianne
Ameta, Sandeep	Kondo, Michelle C.
An, Chunjiang	Kurppa, Sirpa
Assari, Shervin	L. Schmitz, Cathryne
Benatar, Solly	Liao, Chen
Berber, Nemanja	López-Sánchez, Jesús
Blaise, Nguendo Yongsi	Macioce, Fabio
Brack, Andre	Madra-Sawicka, Magdalena
Busby, Joshua W.	Magliocco, Adriano
Capraro, Valerio	Martin, Wanda
Chen, Chong	McFarlane, Ro
Cole, Jennifer	Melo, Pedro
Comas-Garcia, Andreu	Mizuuchi, Ryo
Craig, Jeffrey	Myers, Samuel
Crnogorac-Jurcevic, Tatjana	Najjar, Mohammad
D’Anna, Linda	Nam, Taewoo
Davidove, Marian E.	Nazarko, Lukasz
Dettori, Marco	Occelli, Florent
Díez Ruiz, Fernando	Okulicz-Kozaryn, Adam
Dillon, Denise	Ong, Corinne
Domingo-Irigoyen, Silvia	Papadakaki, Maria
Drawert, Brian	Pateiro, Mirian
Elbarazi, Iffat	Petrikova, Ivica
Fairen, Alberto	Plichta, Marta
Featherstone, Mark	Pombo, Ana
Fernando, Julian	Price, Dan
Fojcik, Marcin	Ribeiro, Helena
Foucher, Frédéric	Rosa, Flavio
Glombik, Konrad	Rugheimer, Sarah
Gray, Tim	Sacco, Pier
Greblikaite, Jolita	Samoila, Cornel
Gu, Fu	Shaw, Margie Hodges
Hall, James	Song, Zhaoli
Hancock, Trevor	Sybesma, Wilbert
Heo, Hyun Hee	Vanegas, Diana C.
Islam, Mohammad Mazharul	Varma, Vijaykumar B.
Jankowska, Marta	Voss, Joachim
Karabasevic, Darjan	Warner, Elyse
Kelly, Daniel	Webb, Darren
Keramydas, Christos	White, Brandi M.
Kingsley, Jonathan	Wu, Jianyong
Kirakosyan, Lyusyena