In Memoriam

Sivabal Sivaloganathan, chair of Waterloo’s Department of Applied Mathematics from 2016 to 2023, and professor of Applied Mathematics from 1990 to present, passed away on March 2, 2025, after a brief illness.

Siv was a visionary mathematician, a dedicated mentor and a leading figure in the integration of mathematics and medicine. His groundbreaking contributions to continuum mechanics, biomechanics and mathematical oncology have left an enduring impact on applied mathematics and the biomedical sciences. During his career, Siv had an oversized impact on the Department of Applied Mathematics, the Faculty of Mathematics and the University of Waterloo.

“As chair of the Department of Applied Mathematics, long-time co-director of the Fields Centre for Mathematical Medicine, a Faculty of Mathematics Senator from 2022 to present and through many other contributions, Siv Sivaloganathan has shaped the Waterloo community in countless ways,” says Mark Giesbrecht, Dean of Mathematics. “Beyond his professional achievements, Siv touched the lives of so many colleagues and students, many of whom considered him a dear friend.”

Early years

Born in Sri Lanka, Siv spent his formative years in the UK, where he attended the British prep and public school system before pursuing his passion for mathematics at Oxford University. His journey took him from a postdoctoral research position at Oxford to a faculty role at the University of Alberta, before ultimately finding his academic home at the University of Waterloo.

Despite the initial cultural shift, Siv embraced Canada as his new home - a decision he never regretted. It was in Toronto that he met his wife, and together they built a life beyond academia, raising four children who now thrive in the US and Canada.

Pioneer in mathematical medicine research

Siv's research was deeply interdisciplinary, pioneering mathematical modeling of complex medical problems. His contributions to mathematical oncology were particularly influential, as he applied advanced computational and mathematical techniques to model cancer progression and treatment response. His work in biomechanics, including brain tissue modeling and hydrocephalus, provided new insights into cerebrospinal fluid dynamics and the mechanical properties of the brain, with critical implications for neurosurgery and medical imaging. His research also extended to high-intensity focused ultrasound (HIFU) as a cancer therapy, where his mathematical models played a pivotal role in refining treatment protocols.

Siv in the classroom in 2001.

Beyond his research, Siv was a dedicated mentor and educator, profoundly impacting his students. He supervised numerous graduate students and postdoctoral researchers, many of whom have gone on to successful careers in academia and industry. Known for his patience, generosity and ability to inspire curiosity, Siv had a rare gift for nurturing talent. Many of his former students credit him for shaping their careers and instilling a rigorous yet creative approach to problem-solving.

“Siv was an exceptional mentor, collaborator and friend. His dedication to excellence, his passion for discovery and his kindness have left an indelible mark on all of his students and postdocs,” says Mohammad Kohandel, one of his close collaborators in the Department of Applied Mathematics. “He has touched the lives of many, sparking in us a drive to explore, innovate and excel. His ability to seamlessly blend rigorous mathematics with real-world applications has set a standard that will continue to inspire future generations of researchers.”

Fields Centre for Mathematical Medicine and awards

Siv also played a pivotal role in advancing mathematical medicine through his leadership at the Fields Institute for Research in Mathematical Sciences, where he co-founded the Fields Centre for Mathematical Medicine and served as its long-time co-director. Under his guidance, the centre became a hub for interdisciplinary collaboration, bringing together mathematicians, clinicians and biomedical scientists to address pressing medical challenges.

He was a driving force behind several workshops and conferences on mathematical medicine, fostering collaborations that extended far beyond Canada. Siv was designated a University Research Chair 2011-2018, was named a Fellow of the Society for Mathematical Biology in 2022 and won the CAIMS-Fields Industrial Mathematics Prize in 2023.

Service to the University

Throughout his career, Siv has had a large influence on his department, the Faculty of Mathematics and the University. Among his many notable service contributions, he served as department chair for Applied Mathematics from 2016 to 2023. Before that, he served as the department’s associate chair for graduate studies from 1994 to 2002. “Siv’s generous and supportive style as a chair and a colleague were an inspiration to all of us in Applied Mathematics,” says Hans De Sterck, the current chair of the department. “Siv was well-loved by students and colleagues alike, and his leadership has been instrumental in enhancing the research strength of the department through high-profile hiring and through building lasting connections with partners such as the Perimeter Institute for Theoretical Physics.”

Siv was always a great champion of student and community life in the Faculty of Mathematics. For example, he was a great supporter of the Women in Mathematics (WiM) committee and their flagship Directed Reading Program, for which he was an advisory committee member and a proposal reviewer. “The WiM committee is deeply appreciative of Siv’s contributions in advancing equity, diversity and inclusion,” says Yu-Ru Liu, the current director of WiM. “Siv has been a trusted advisor to me with guidance related to WiM and broader academic life.”

While department chair, Siv’s contributions as a member of the Math Faculty’s leadership team were also highly appreciated, as well as his contributions to the University as a Senator from 2022 until present.

Legacy

Siv Sivaloganathan’s legacy will live on through the many lives he touched and the groundbreaking work he advanced. “Siv was a shining star in the Math Faculty, always cheerful and optimistic,” says Alfred Menezes, a longtime colleague and friend. “He was a dear friend to many of us, as well as a mentor, teacher and research collaborator. He will be deeply missed.”

This obituary was originally posted in the Waterloo News.

Dr. Ian James McGee, a professor emeritus of Applied Mathematics at the University of Waterloo, died on February 20, 2025. He was 87.

McGee was born on November 9, 1937, in Toronto, ON, one of four siblings. A “renegade” as a child, he frequently got in trouble in elementary school, with the principal once telling his parents that “at this rate, Ian won’t make it past grade eight.”

McGee's attitude towards school changed thanks to his sixth grade math teacher, who introduced him to logic puzzles and ignited his lifelong love of math and science. With the mentorship of other teachers throughout the years, he began to thrive at school, ultimately graduating as high school valedictorian.

McGee also met his beloved wife, Dawna, as a child: they grew up a block away from each other and attended the same elementary school, beginning to date in Grade Thirteen.

McGee earned his Bachelor of Applied Science, Engineering Physics from the University of Toronto in 1960. He then came to the University of Waterloo for the first time, earning his Master’s of Science in 1961. A PhD in Theoretical Physics at Yale University followed in 1965, then post-doctoral studies at the University of Wisconsin from 1966 to 1967.

In 1967, McGee was hired by the University of Waterloo as an associate professor in Applied Mathematics. He remained with the Applied Mathematics department throughout the rest of his career, save for an eighteen-month term as a visiting professor at the University of Newcastle & Australia University from 1974 to 1975.

McGee served as associate dean of the Faculty of Mathematics from 1976 to 1980. Reflecting the pivotal role his own teachers played in his life, he was passionate about education. In 1991, he received the Centre for Teaching Excellence’s Distinguished Teacher Award. As one of his former students noted in the citation, “Not only has he been able to teach the subject matter itself in a useful and interesting manner, but his attitude towards mathematics and his enjoyment of its applicability has nurtured and strengthened a similar attitude in me. This attitude and his skill in presenting a subject clearly and truly without a dull moment have convinced me that mathematics is indeed a wonderful science.”

While McGee was never official part of the Centre for Education in Mathematics and Computing (CEMC), he was a longstanding “friend” of the Centre, participating regularly in math contest creation and marking. As retired CEMC member Ed Anderson recalls, “Any activity that involved engaging with young people was not something that Ian ever considered as work.”

McGee and his wife Dawna had three daughters and six grandchildren. An avid amateur athlete, he won many awards as an A-level squash player at Northfield Racquet Club, and enjoyed watching sports live and on TV throughout his life. He also loved to travel, visiting every continent including Antarctica. He was accompanied on many of these trips by his family, and particularly enjoyed cruises with his family, and adventures with his son-in-law Robin, who is a naturalist and trip leader.  A self-taught classical guitarist, he particularly enjoyed learning and singing Australian folk songs during his term as a visiting professor.

After retirement, McGee stayed active, enjoying puzzles and games, numerous crafts, and outdoor activities. He spent time volunteering in hospice care, clowning with his sister Janet, and serving as an elder at St. Andrews Presbyterian Church. In 2008, in recognition of his work in hospice care, he received the Ontario Medal for Good Citizenship. The citation notes his frequent visits with “palliative care patients and those with Alzheimer’s Disease, offering them compassionate and practical support.”

McGee is survived by his sisters Heather and Janet, his wife Dawna, and his children and grandchildren, as well as their partners. “He was loved by many,” his family notes in his obituary, “and his stories of his life (and his jokes) will continue on.”

Visitation will be held at the Erb & Good Family Funeral Home on Saturday, April 5, from 10-11 a.m. The funeral service will take place in the chapel of the funeral home at 11 a.m. followed by a reception in the Fireside Reception Room. A livestream and recording of the service will be made available on Ian’s tribute page.

In lieu of flowers, condolences for the family and donations to Hospice Waterloo or the Alzheimer Society may be arranged through the Erb & Good Family Funeral Home.

This obituary was originally posted in the Math Faculty news.

We extend our deepest condolences to the family, friends, and colleagues of Jiří Čížek, distinguished professor emeritus of applied mathematics, who died on December 24, 2024, in Toronto. He was 86.

Čížek was born in Prague, Czechoslovakia (now Czechia) on 24 August, 1938, to Václav Čížek and Jiřina Čížková, both physicians. An avid reader and mathematics student from an early age, by 17 Čížek had mastered algebra and calculus at the level of a university graduate. He began collaborating with lifelong mentor Jaroslav Koutecký in 1955, and published his first two papers with him in 1956, the same year Čížek graduated from high school.

That year he enrolled in the Faculty of Mathematics and Physics at Charles University in Prague, researching kinetic currents and earning his master’s degree there in 1961. He then began doctoral research at the Institute of Physical Chemistry of the Czechoslovak Academy of Sciences (now the J. Heyrovský Institute), graduating in 1965. His research into quantum chemistry and the many-body problem – particularly his proposed use of coupled-cluster methodology for the study of electronic correlation effects in atoms and molecules – laid the groundwork for numerous developments in quantum chemistry over the following decades.

Following the 1968 Warsaw Pact invasion, he moved to Canada with his family and joined the University of Waterloo’s young Applied Mathematics department. He was cross-appointed to the Department of Chemistry in 1973, and throughout the years also served as an affiliate professor at the University of Florida in Gainesville and an adjunct professor at Charles University in Prague. At Waterloo, he supervised or co-supervised six M.Sc. and M.Math. and thirteen Ph.D. theses, and collaborated with numerous post-doctoral researchers, visiting scholars, and colleagues.

A globally recognized researcher in quantum chemistry, Čížek is most well-known for introducing Coupled Cluster Theory to describe electron correlation in atoms and molecules. He authored or co-authored more than 175 papers throughout his career, and received numerous prestigious awards including an Alfred P. Sloan Fellowship and the Alexander von Humboldt Senior Scientist Award (1994).

“Jiří Čížek had an illustrious scientific career and was without doubt one of the giants of intellectual life in the history of Waterloo’s Department of Applied Mathematics,” says Hans De Sterck, chair of the Department of Applied Mathematics. “A number of my colleagues here in the department have known him as a great researcher, teacher, colleague, and friend, and he will be greatly missed.”

Čížek was a member of the International Academy of Quantum Molecular Science and a Fellow of the Royal Society of Canada. He retired from the University of Waterloo in 1996, receiving the title “Distinguished Professor Emeritus,” but continued for years in his work as an adjunct professor at Charles University.  

Čížek met his wife Ludamila Zamazalová while in graduate school. The pair married in 1963, and remained inseparable until her death in 2008. “Without her,” Čížek said, “I would finish very badly when I was young.” The couple had two children: Petr, a town and regional planner, and Katerina, an award-winning documentary filmmaker.

Čížek died on Christmas Eve, surrounded by family. His ashes will be interred at the family grave in Prague in a private service.

This obituary was originally posted in the Math Faculty news.

Prof. Paldus obtained his M.Sc. Degree in 1958 from the Faculty of Mathematics and Physics of the Charles University in Prague, Czechia, and his Ph.D. (CSc.) in 1961 from the Institute for Physical Chemistry of the Czechoslovak Academy of Sciences, the same year he married his lifetime partner, Eva.  From 1962 to 1964, he pursued his postdoctoral studies at the Division of Pure Physics of the National Research Council of Canada in Ottawa under the guidance of Dr. Don Ramsey and Dr. Gerhard Herzberg.

In 1968, after emigrating to Canada, he became an Associate Professor in the Department of Applied Mathematics at the fledgling University of Waterloo in Waterloo, Ontario, Canada.  Seven years later, he was promoted to Full Professor in both the Applied Mathematics and Chemistry Departments, and continued help build a world class department.  In 1984, he joined the Quantum Theory Project and also served as an Adjunct Professor in the Department of Chemistry at the University of Florida, Gainesville.  He was also the Associate Director of The Fields Institute for Research in Mathematical Sciences in Toronto, Ontario, Canada, from 1991 to 1994.  Until his death, he continued to serve as a Distinguished Professor Emeritus in the Quantum Theory Group, in the Department of Applied Mathematics at the University of Waterloo.

Prof. Paldus leaves behind a great body of work on coupled cluster theory, where he and Jiří Čížek adapted the many-body coupled cluster method to many-electron systems, thus making it a viable method in the study of the electronic correlation that occurs in atoms and molecules.   He was also well-known for his contributions to the Unitary Group Approach. This approach regards the computation of Hamiltonian matrix elements over N-electron spin eigenstates that appear in electronic correlation problems.

During his remarkable career spanning over 6 decades, he served as a Visiting Professor at several universities and research institutions in such countries as France, Germany, Italy, The Netherlands, and Israel, as well as organizing many international conferences and summer schools.  Amongst many international prizes and honors, he received honorary degrees from Charles University Prague, Bratislava, and Strasbourg, as well as becoming a Fellow of the Royal Society of Canada and the American Institute of Physics.   He also served as a member of numerous editorial and advisory boards of scientific journals in chemical physics, including the International Journal of Quantum Chemistry, Advances in Quantum Chemistry, Journal of Chemical Physics, Therotica Chimica Acta, Journal of Mathematical Chemistry, and the Canadian Journal of Chemistry. 

A number of you will have known "Joe" as teacher, colleague, friend. He will be greatly missed and the world will not be the same without him.