PERSONEN FILTERS: s=, field=theoretical physics
Gevonden personen:
Member Group(s)
- KNAW-Lid

Variant Names
N/ABIO
Dissertation: N/AHighest degree: N/A
Fields of interest:
Biography:
N/A
Residence
- Paris 
Occupation
N/AEducation
N/AMembership
- Koninklijke Nederlandsche Akademie van Wetenschappen
Foreign Member Afd. Natuurkunde 11-05-1897
Provenance
- Ledenlijst in: De leden van de Koninklijke Nederlandse Akademie van Wetenschappen. Een demografisch perspectief: 1808 tot 2008. Kaa, D.J. vam de, Roo, Y. de. KNAW Press (2008)
Publications
N/AMember Group(s)
- KNAW-Lid

Variant Names
N/ABIO
Dissertation: N/AHighest degree: N/A
Fields of interest:
Biography:
N/A
Residence
- Princeton 
Occupation
N/AEducation
N/AMembership
- Koninklijke Nederlandsche Akademie van Wetenschappen
Foreign Member Afd. Natuurkunde 20-05-1960
Provenance
- Wigner, E.P., Levensberichten en herdenkingen 1998, p. 81-85 door N.G. van Kampen.
Publications
N/AMember Group(s)
- KNAW-Lid

Variant Names
N/ABIO
Dissertation: N/AHighest degree: N/A
Fields of interest:
Biography:
Dutch physicist
Residence
- Waalre 
Occupation
N/AEducation
N/AMembership
- Koninklijke Nederlandsche Akademie van Wetenschappen
Member Afd. Natuurkunde 20-06-1978
Provenance
- Polder, D., Levensberichten en herdenkingen 2002, p. 57-63 door Q.H.F. Vrehen.
Publications
N/AMember Group(s)
- KNAW-Lid

Variant Names
N/ABIO
Dissertation: N/AHighest degree: N/A
Fields of interest:
Biography:
N/A
Residence
- Leiden 
Occupation
N/AEducation
N/AMembership
- Koninklijke Nederlandsche Akademie van Wetenschappen
Member Afd. Natuurkunde 27-06-1979
Provenance
- Kasteleyn, P.W., Levensberichten en herdenkingen 1997, p. 19-22 door J.M.J. van Leeuwen.
Publications
N/AMember Group(s)
- KNAW-Lid

Variant Names
- Tjon, J.A.
BIO
Dissertation: Quantum Statistical Theory of Relaxation in Isolated Spin Systems (1964)Highest degree: Prof. dr.
Fields of interest:
Biography:
N/A
Residence
- Bilthoven 
Occupation
N/AEducation
N/AMembership
- Koninklijke Nederlandsche Akademie van Wetenschappen
Member Afd. Natuurkunde 28-04-1997 - 20-09-2010
Provenance
- Levensberichten en herdenkingen 2012, Amsterdam, 2012, 84-89
Publications
N/A
Christoffel Jacob Bouwkamp
MALEHoogkerk, Netherlands 26-06-1915 - † Eindhoven, Netherlands 23-02-2003
Member Group(s)
- KNAW-Lid

Variant Names
N/ABIO
Dissertation: N/AHighest degree: N/A
Fields of interest:
Biography:
N/A
Residence
- Eindhoven 
Occupation
N/AEducation
N/AMembership
- Koninklijke Nederlandsche Akademie van Wetenschappen
Member Afd. Natuurkunde 20-05-1960
Provenance
- Bouwkamp, C.J., Levensberichten en herdenkingen 2004, p. 12-17 door A.T. de Hoop.
Publications
-
On the dissection of rectangles into squares. (Third communication.) Year: . Pages: 7. (PDF format)
-
A note on Mathieu functions Year: . Pages: 3. (PDF format)
-
On the theory ofspheroidal wave functions of order zero Year: . Pages: 14. (PDF format)
-
On the construction of simple perfect squared squares Year: . Pages: 2. (PDF format)
-
On integrals occurring in the theory of diffraction of electromagnetic waves by a circular disc Year: . Pages: 8. (PDF format)
-
On the dissection of rectangles into squares. (First communication.) Year: . Pages: 13. (PDF format)
-
On the dissection of rectangles into squares. (Second communication.) Year: . Pages: 14. (PDF format)
-
A study of Bessel functions in connection with the problem of two mutually attracting circular discs Year: . Pages: 7. (PDF format)
-
On the mutual inductance of two parallel coaxial circles of circular cross-section Year: . Pages: 11. (PDF format)
-
On the evaluation of certain integrals occurring in the theory of the freely vibrating circular disk and related problems Year: . Pages: 8. (PDF format)
Member Group(s)
- KNAW-Lid

Variant Names
N/ABIO
Dissertation: N/AHighest degree: N/A
Fields of interest:
Biography:
N/A
Residence
- Delft 
Occupation
N/AEducation
N/AMembership
- Koninklijke Nederlandsche Akademie van Wetenschappen
Member Afd. Natuurkunde 12-06-1946 - Koninklijke Nederlandsche Akademie van Wetenschappen
Foreign Member Afd. Natuurkunde 01-10-1969
Provenance
- Kronig, R., Levensberichten en herdenkingen 1996, p. 55-60 door H.B.G. Casimir.
Publications
N/AMember Group(s)
- KNAW-Lid

Variant Names
N/ABIO
Dissertation: N/AHighest degree: N/A
Fields of interest:
Biography:
N/A
Residence
- Utrecht 
Occupation
N/AEducation
N/AMembership
- Koninklijke Nederlandsche Akademie van Wetenschappen
Foreign Member Afd. Natuurkunde 01-09-1961 - Koninklijke Nederlandsche Akademie van Wetenschappen
Member Afd. Natuurkunde 20-05-1959
Provenance
- Hove, L.C.P. van, Levensberichten en herdenkingen 1992, p. 21-26 door N.G. van Kampen.
Publications
N/A
Hendrik Brugt Gerhard Casimir
MALEDen Haag, Netherlands 17-07-1909 - † Heeze, Netherlands 04-04-2000
Member Group(s)
- KNAW-Lid

Variant Names
N/ABIO
Dissertation: N/AHighest degree: PhD (1931, Leyden University)
Fields of interest:
Biography:
N/A
Residence
- Heeze 
Occupation
- Assistant to Wolfgang Pauli, Zurich (1932-1933); Senior assistant, and Curator, Kamerlingh Onnes Laboratory (1936); Extraordinarius Professor of Physics, Leyden (1939-1942); worked in Philips Company research laboratory, Eindhoven (1942); Co-director, Philips Research Laboratories (1946-1972); Member of the Board of Directors with responsibility for research, Philips (1956-1972); his 80th birthday was celebrated with a symposium in Eindhoven (1989) 
Education
N/AMembership
- Koninklijke Nederlandsche Akademie van Wetenschappen
Member Afd. Natuurkunde 12-06-1946 - Royal Society of London
Foreign Member 23-04-1970
Provenance
- Casimir, H.B.G., Levensberichten en herdenkingen 2001, p. 13-21 door D. Polder.
Publications
Member Group(s)
- KNAW-Lid

Variant Names
N/ABIO
Dissertation: Contribution to the theory of compressed gases (Universiteit van Amsterdam, 1940)Highest degree: Prof. dr.
Fields of interest:
Biography:
N/A
Residence
- Amsterdam 
Occupation
N/AEducation
N/AMembership
- Koninklijke Nederlandsche Akademie van Wetenschappen
Member Afd. Natuurkunde 22-05-1953 - 15-02-2010
Provenance
- Ledenlijst in: De leden van de Koninklijke Nederlandse Akademie van Wetenschappen. Een demografisch perspectief: 1808 tot 2008. Kaa, D.J. vam de, Roo, Y. de. KNAW Press (2008)
Publications
N/AMember Group(s)
- KNAW-Lid

Variant Names
N/ABIO
Dissertation: N/AHighest degree: N/A
Fields of interest:
Biography:
N/A
Residence
- Amsterdam 
Occupation
N/AEducation
N/AMembership
- Koninklijke Nederlandsche Akademie van Wetenschappen
Member Afd. Natuurkunde 19-05-1958
Provenance
- Groot, S.R. de, Levensberichten en herdenkingen 1995, p. 35-39 door P. Mazur.
Publications
-
Sur l'intégration de quelques problèmes aux limites régis par l'équation de FOURIER dite "de la chaleur" au moyen de la méthode des transformations fonctionnelles simultanées Year: . Pages: 6. (PDF format)
-
Sur l'intégration de quelques problèmes aux limites régis par l'équation de FOURIER dite "de la chaleur" au moyen de la méthode des transformations fonctionnelles simultanées Year: . Pages: 7. (PDF format)
Member Group(s)
- KNAW-Lid

Variant Names
N/ABIO
Dissertation: N/AHighest degree: N/A
Fields of interest:
Biography:
N/A
Residence
- Oxford 
Occupation
N/AEducation
N/AMembership
- Koninklijke Nederlandsche Akademie van Wetenschappen
Correspondent Afdeling Natuurkunde 02-06-1966
Provenance
- Haar, D., Levensberichten en herdenkingen 2004, p. 52-54 door N.G. van Kampen.
Publications
N/AMember Group(s)
- KNAW-Lid

Variant Names
N/ABIO
Dissertation: N/AHighest degree: N/A
Fields of interest:
Biography:
N/A
Residence
- Den Haag 
Occupation
N/AEducation
N/AMembership
- Koninklijke Nederlandsche Akademie van Wetenschappen
Member Afd. Natuurkunde 10-06-1970
Provenance
- Mazur, P., Levensberichten en herdenkingen 2005, p. 86-89 door N.G. van Kampen.
Publications
N/A
Ezechiël Godert David Cohen Cohen
MALEAmsterdam, Netherlands 16-01-1923 - † Iowa City, United States 27-09-2017
Member Group(s)
- KNAW-Lid

Variant Names
- Cohen, Eddie
BIO
Dissertation: On the theory of the liquid state (Amsterdam, 1957)Highest degree: PhD
Fields of interest:
Biography:
N/A
Residence
N/AOccupation
N/AEducation
- student theoretical physics  - Universiteit van Amsterdam, Amsterdam
Membership
- Koninklijke Nederlandsche Akademie van Wetenschappen
Correspondent Afdeling Natuurkunde 27-06-1979 - 2017
Provenance
- https://en.wikipedia.org/wiki/E.G.D._Cohen
- De leden van de Koninklijke Nederlandse Akademie van Wetenschappen. Een demografisch perspectief: 1808 tot 2008. Amsterdam, Koninklijke Nederlandse 2008. Kaa, D.J. van de, Roo, Y. de
- Levensberichten en herdenkingen 2018, Amsterdam 2018, J.M.J. van Leeuwen, p. 42-47
Publications
N/A
Johan Willem van Vredenburch
MALEDelft, Netherlands 06-08-1782 - † Rijswijk, Netherlands 14-12-1849
Member Group(s)
- Genootschaps-lid
- KNAW-Lid

Variant Names
- Vredenburch, Jhr. Johan Willem van
BIO
Dissertation: de prohibitis nuptiis inter tutorem et pupillam ex jure Romano et hodiernoHighest degree: mr.
Fields of interest:
Biography:
N/A
Residence
- Den Haag 
Occupation
- vroedschap der stad 1808, Delft
- hoofdingeland van Delfland 1815
- schout en burgemeester 1815 - 1847, Rijswijk
Education
- student  - Latijnsche School Delft
- law student 1802 - 1805 - Hogeschool Leiden
Membership
- Koninklijk Instituut, eerste klasse
Correspondent, living in the Netherlands 19-10-1809 - Gezelschap ter Beoeffening der proefondervindelijke Wijsbegeerte in ’s Hage
member (physics department) 1814 - 1824~ - Maatschappij der Nederlandsche Letterkunde - Leiden
member 1809 - Hollandsche Maatschappij der Wetenschappen - Haarlem
member  - Provinciaal Utrechtsch Genootschap van Kunsten en Wetenschappen
member 
Provenance
- Naamlijst der leden van de Maatschappij voor natuur- en letterkunde (Den Haag 1814).
- Molhuysen, P.C., P.J. Blok en Fr.K.H. Kossmann (redactie), Nieuw Nederlandsch Biografisch Woordenboek. Deel 7. (Leiden 1927) 1297.
- Naamlijst der leden van de Maatschappij voor natuur- en letterkunde (Den Haag 1824).
Publications
N/AMember Group(s)
- KNAW-Lid

Residence
- Strasbourg 
Occupation
N/AEducation
N/AMembership
- Koninklijke Nederlandsche Akademie van Wetenschappen
Foreign Member Afd. Natuurkunde 19-05-1937
Provenance
- Weiss, P.E., Verslagen Natuurkunde 50, 1941, p. 32-33 door J. van der Hoeve; Jaarboek 1941/42, p. 220-225 door J.D. van der Waals Jr.
Publications
N/A
Anthony Hendrik van der Boon Mesch
MALEDelft, Netherlands 15-04-1804 - † Leiden, Netherlands 12-08-1874
Member Group(s)
- Genootschaps-lid
- KNAW-Lid

Variant Names
- Boon Mesch, Anthony Hendrik van der
BIO
Dissertation: de Montibus igne ardentibus Insulae Javae eorundemque lapidibusHighest degree: professor
Fields of interest:
Biography:
N/A
Residence
- Leiden 
Occupation
- lector en (buitengewoon) hoogleraar scheikunde 1826
Education
- student  - Latijnsche School Delft
- mathematics and physics student 1821 - 1826, Leiden
Membership
- Koninklijke Nederlandsche Akademie van Wetenschappen
Member Afd. Natuurkunde 26-10-1851 - Koninklijk Instituut, eerste klasse
Member 15-04-1844 - 26-10-1851 - Koninklijk Instituut, eerste klasse
Correspondent, living in the Netherlands 19-12-1829 - Nederlandsche Maatschappij voor Nijverheid en Handel
Member, director and chairman  - Maatschappij ter bevordering van de Landbouw
Member and member of the board  - Gezelschap ter Beoeffening der proefondervindelijke Wijsbegeerte in ’s Hage
Honorary member 1833 - 1872~
Provenance
- Molhuysen, P.C., en P.J. Blok (redactie), Nieuw Nederlandsch Biografisch Woordenboek. Deel 2. (Leiden 1912) 905.
- Lijst met ere- en bestuursleden van maatschappij Diligentia in de periode 1865-1890 (Den Haag 1890).
Publications
N/AMember Group(s)
- Genootschaps-lid
- KNAW-Lid

Variant Names
N/ABIO
Dissertation: Metingen over het verschijnsel van KerrHighest degree: doctor
Fields of interest:
Biography:
Zeeman was born to Wilhelmina Worst and Catharinus Farandinus Zeeman, a Lutheran minister. He went to the HBS in nearby Zierikzee and then studied classical languages at the gymnasium in Delft for two years. During this period he published an account of an aurora borealis visible in Zonnemaire. He entered the University of Leiden in 1885, where he studied under Lorentz and Kamerlingh Onnes and became an assistant in Kamerlingh Onnes's laboratory in 1895. He received his doctorate in 1893 for a dissertation on the so-called Kerr Effect, for the research of which he had received the gold medal of the Hollandsche Maatschappij in the previous year. After a year in Strasbourg at the Kohlrausch Institute, he became privat-dozent at Leiden and married Elisabeth Lebret, with whom he had a son and three daughters. From 1896 until his retirement, Zeeman was on the faculty of the University of Amsterdam (lecturer, 1896, extraordinarius, 1900, ordinarius, 1908). In 1908 he succeeded Van der Waals as the director of the university's physics laboratory, the Physics Institute.
While still at Leiden, Zeeman discovered the effect named-after him. He was searching for an interaction between magnetic and optical effects. Faraday had investigated the effect of a magnetic field on spectral lines as early as 1862, but without a positive result. Zeeman repeated the experiment, using a diffraction grating of high resolving power and found that the emission line of sodium was broadened (1896). Lorentz and Zeeman explained the phenomenon by supposing that the electron (discovered the previous year by JJ. Thomson) moved within the atom and emitted light. Measurements of the frequencies at the extremes of the broadened line allowed them to determine the e / m ratio. At Amsterdam, the following year, Zeeman was able to split the sodium line into a triplet, as predicted by Lorentz. For this work Zeeman and Lorentz received the Nobel Prize in physics in 1902.
Zeeman continued his research on the Zeeman effect, but the limitations of his laboratory in Amsterdam prevented great accuracy. This problem was not overcome until the construction of a new laboratory in 1923 (since 1940 the Zeeman Laboratory). He also measured the velocity of light in moving media, showing that the value of the Fresnel coefficient varied with the wavelength, a prediction of relativity theory. Only after 1923 did he return to measurements of the Zeeman effect, measuring the spectral lines of several noble gases and rhenium. Zeeman served as secretary (1912-1920) and chairman (1931) of the Physics division of the Royal Academy of Arts and Sciences, as president of the Commission Internationale des Poids et Mesures in Paris from 1940 to 1943, and as rector magnificus of the university of Amsterdam from 1920 to 1923. He received honorary doctorates from ten universities and prizes from the most prestigious scientific societies, including the Académie des Sciences, the Royal Society, and the National Academy of Sciences. With A.D. Fokker, he edited the papers of H.A. Lorentz ('s-Gravenhage: Martinus NijhofF, 1934- 1939).
Residence
- Amsterdam 
- Leiden 
Occupation
N/AEducation
- student , Leiden
Membership
- Koninklijke Nederlandsche Akademie van Wetenschappen
Member Afd. Natuurkunde 13-05-1898 - Royal Society of London
Foreign Member 05-05-1921 - Nederlands Natuur- en Geneeskundig Congres
Member [..1890]
Provenance
- Zeeman, P., Verslagen Natuurkunde 52, 1943, p. 465-466 door H.R. Kruyt; Jaarboek 1943/44,p. 208-218 door J.D. van der Waals Jr.
- Biografie opgenomen in History of Science and Scholarship in the Netherlands
- Ledenlijst Vereeniging het Nederl. Natuur- en Geneesk. Congres (1890).
- P.F.A. Klinkenberg, 'Zeeman, Pieter (1865-1943)', in Biografisch Woordenboek van Nederland. URL:http://resources.huygens.knaw.nl/bwn1880-2000/lemmata/bwn1/zeeman [12-11-2013].
Publications
-
Direct optical measurement of the velocity at the axis in the apparatus for Fizeau's experiment Year: . Pages: 9. (PDF format)
-
The intensities of the components of spectral lines divided by magnetism Year: . Pages: 6. (PDF format)
-
New observations concerning asymmetrical triplets Year: . Pages: 11. (PDF format)
-
Magnetic resolution of spectral lines and magnetic force. (1st part.) Year: . Pages: 6. (PDF format)
-
Fresnel's coefficient for light of different colours. (Second part) Year: . Pages: 13. (PDF format)
-
Observations of the magnetic resolution of spectral lines by means of the method of Fabry and Perot Year: . Pages: 8. (PDF format)
-
Observations on the magnetic rotation of the plane of polarisation in the interior of an absorption band Year: . Pages: 8. (PDF format)
-
Some observations on the resolving power of the MICHELSON echelon-spectroscope Year: . Pages: 6. (PDF format)
-
Change of wavelength of the middle line of triplets. (Second Part) Year: . Pages: 6. (PDF format)
-
On the passage of light through the slit of a spectroscope Year: . Pages: 5. (PDF format)
Member Group(s)
- KNAW-Lid

Variant Names
N/ABIO
Dissertation: N/AHighest degree: N/A
Fields of interest:
Biography:
De Haas was born to Albertus de Haas and Maria Efting. He attended primary school and HBS in Middelburg, where his father was head of the Rijksleerschool (a teachers' school). Starting in 1895, De Haas worked in the office of a notary, while he studied for the professional examinations (passing two of the three parts). In 1900 he passed the state examination in Greek and Latin and enrolled at the university of Leiden. From 1905 to 1911, he was an assistant in the laboratory of Kamerlingh Onnes and Kuenen, passing his doctoral examination in 1910. From 1911 to 1913, he served as assistant to H. E. J. G. du Bois at the Bosscha Laboratorium in Berlin. In 1912, he received his doctorate under Kamerlingh Onnes for a dissertation on Metingen over de compressibiliteit van waterstof, in het bijzonder van waterstofdamp bij en beneden het kookpunt (Measurements of the Compressibility of Hydrogen, in particular of Hydrogen vapor near and below the Boiling Point). In that year, De Haas and P. Drapier discovered an ingenious method of determining the diamagnetic susceptibility of water, a discovery that led to his appointment as 'wissenschaftlicher Mitarbeiter' at the Physikalisch Technische Reichsanstalt in Berlin, 1913-1915.
World War I forced De Haas to leave Germany. He taught physics at the HBS and Gymnasium at Deventer for a year, and in 1916 became curator at Teyler's Museum in Haarlem, where Lorentz was the chief curator. But before leaving Berlin, in 1915, De Haas had begun working with Einstein on molecular currents which give rise to permanent molecular magnets. De Haas's experiments led to the formulation of the so-called Einstein-De Haas Effect, for which he and Einstein received the Baumgartner Prize of the Viennese Academy of Sciences in 1917. In that same year, De Haas was appointed to the chair of applied physics at the Technical College at Delft, in 1922 he accepted the chair of physics at the university of Groningen and was elected to membership of the Royal Academy of Arts and Sciences, in 1923, he became a member of the Hollandsche Maatschappij der Wetenschappen.
Upon the retirement of Heike Kamerlingh Onnes, De Haas succeeded him in 1924 as professor of physics and meteorology at the University of Leiden. With Keesom, he became co-director of the Physics Laboratory (officially named the Kamerlingh Onnes Laboratorium in 1932) and headed the electromagnetic department. De Haas worked with a number of co-workers in cryogenic research. Under his leadership, the new method of reaching ultra-low temperatures, adiabatic demagnetization, was developed: by 1935, De Haas and his team had reached a temperature of 0.005 °K. But his research was by no means restricted to this work. Together with coworkers, De Haas made paramagnetic measurements that gave clearer insight into the structure of atoms and investigated magnetic moments of ions in crystals.
De Haas was one of the most important low-temperature physicists of the first half of the twentieth century. He took part in the Solvay Congresses of 1921 and 1930, was honored by Royal Society of London with the Rumford Medal, was an honorary member of the Société française de physique, and gave the Scott Lectures at Cambridge in 1937. In Leiden, he served as the president of the society that governed the school for instrument makers from 1926 to 1951.
In 1939, De Haas advised the Dutch government to buy quantities of uranium oxide that came on the market that year. His advice was followed, and the uranium oxide remained hidden in a laboratory in Delft during World War II. After the war, it became the foundation of a cooperative Norwegian-Dutch nuclear energy project. During World War II, De Haas had freedom to move around because of his cooperation with Cellastic, an organization that worked for the Germans. As a result, he was able to escape to England. For this cooperation, he was investigated after the war, and from June to October 1945 he was suspended as professor, after which he resumed Ms role and occupied the chair of experimental physics at Leiden until his retirement in 1948.
Residence
- Bilthoven 
Occupation
N/AEducation
N/AMembership
- Koninklijke Nederlandsche Akademie van Wetenschappen
Member Afd. Natuurkunde / (forced to resign) 23-05-1922 - 23-12-1942 - Koninklijke Nederlandsche Akademie van Wetenschappen
Member Afd. Natuurkunde 20-07-1945
Provenance
- Haas, W.J. de, Verslagen Natuurkunde 69, 1960, p. 52-53 door M.W. Woerdeman; Jaarboek 1959/60, p. 300-303 door C.J. Gorter.
- Biografie opgenomen in History of Science and Scholarship in the Netherlands
Publications
-
Isotherms of diatomic gases and of their binary mixtures. XI. On determinations with the volumenometer of the compressibility of gases under small pressures and at low temperatures Year: . Pages: 9. (PDF format)
-
On the diffraction phenomenon caused by a great number of irregularly distributed apertures or opaque particles Year: . Pages: 12. (PDF format)
-
Isotherms of diatomic gases and of their binary mixtures. X. Control measurements with the volumenometer of the compressibility of hydrogen at 20º C. Year: . Pages: 6. (PDF format)
-
Isotherms of diatomic gases and of their binary mixtures VIII. control measurements with the volumenometer Year: . Pages: 17. (PDF format)
-
Further experiments on the moment of momentum existing in a magnet Year: . Pages: 20. (PDF format)
-
The effect of temperature and transverse magnetisation on the continuous-current resistance of crystallized antimony Year: . Pages: 15. (PDF format)
Member Group(s)
- KNAW-Lid

Variant Names
N/ABIO
Dissertation: N/AHighest degree: N/A
Fields of interest:
Biography:
N/A
Residence
- London 
Occupation
N/AEducation
N/AMembership
- Koninklijke Nederlandsche Akademie van Wetenschappen
Foreign Member Afd. Natuurkunde 24-06-1947
Provenance
- Holmes, A., Jaarboek 1965/66, p. 380-382 door Ph.H. Kuenen.