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Amsterdam-Zuidoost, Netherlands

Hanselmann M.,The Interdisciplinary Center | Roder J.,The Interdisciplinary Center | Roder J.,Robert Bosch GmbH | Kothe U.,The Interdisciplinary Center | And 3 more authors.
Analytical Chemistry | Year: 2013

Digital staining for the automated annotation of mass spectrometry imaging (MSI) data has previously been achieved using state-of-the-art classifiers such as random forests or support vector machines (SVMs). However, the training of such classifiers requires an expert to label exemplary data in advance. This process is time-consuming and hence costly, especially if the tissue is heterogeneous. In theory, it may be sufficient to only label a few highly representative pixels of an MS image, but it is not known a priori which pixels to select. This motivates active learning strategies in which the algorithm itself queries the expert by automatically suggesting promising candidate pixels of an MS image for labeling. Given a suitable querying strategy, the number of required training labels can be significantly reduced while maintaining classification accuracy. In this work, we propose active learning for convenient annotation of MSI data. We generalize a recently proposed active learning method to the multiclass case and combine it with the random forest classifier. Its superior performance over random sampling is demonstrated on secondary ion mass spectrometry data, making it an interesting approach for the classification of MS images. © 2012 American Chemical Society. Source


Heeren R.M.A.,FOM AMOLF
International Journal of Mass Spectrometry | Year: 2014

This retrospective on imaging mass spectrometry describes the coming of age of an approach that has matured from an innovative technological development to a broadly applied analytical tool. A look back in time reveals how the breadth of imaging mass spectrometry has expanded from a purely (semiconductor) surface physics field to its recent impact on biomedicine, nanotechnology and culture. The impact of historical milestones in desorption and ionization technologies on the progress in modern multimodal molecular imaging technologies is described and discussed. A concise picture is sketched of the roadmap that contains the key advances in imaging mass spectrometry methods and technologies. © 2014 Elsevier B.V. All rights reserved. Source


Gademann G.,FOM AMOLF | Ple F.,Amplitude | Paul P.-M.,Amplitude | Vrakking M.J.J.,FOM AMOLF | Vrakking M.J.J.,Max Born Institute for Nonlinear Optics and Short Pulse Spectroscopy
Optics Express | Year: 2011

We demonstrate the first carrier-envelope phase (CEP)-stabilized chirped pulse amplification system with pulse peak-powers in the terawatt regime. The system, which eventually is intended to be used in the generation of isolated attosecond pulses, consists of two consecutive multipass amplification stages. The first amplification stage is a commercial CEP-stable kHz system including a single 13-pass amplifier reaching a pulse energy of 2.3 mJ. Pulses are picked after the first stage at a repetition rate of 50 Hz and are further amplified in a 5-pass power-amplifier to pulse energies that reach up to 80 mJ before compression. After compression the pulse energy is 35mJ at a pulse duration of 32 fs, signifying a peak power of 1.1 terawatt. Peak-powers exceeding 1.5 TW should easily be achievable by improving the efficiency of the grating compressor. The CEP-stability of the terawatt system is demonstrated by single shot measurements of the residual CEP jitter at the full repetition rate and show an excellent root-mean-square value of 315 mrad. © 2011 Optical Society of America. Source


Anielski D.,Max Planck Advanced Study Group at CFEL | Anielski D.,Max Planck Institute for Nuclear Physics | Boll R.,Max Planck Advanced Study Group at CFEL | Boll R.,Max Planck Institute for Nuclear Physics | And 52 more authors.
Optics InfoBase Conference Papers | Year: 2012

We present static and time-resolved photoelectron angular distributions of laser-aligned p-fluorophenylacetylene and OCS molecules photoionized by fs-FEL pulses. The results are a proof-of-principle for recording dynamic structural changes of a molecule during Coulomb explosion. © 2012 OSA. Source


Anielski D.,Max Planck Advanced Study Group at CFEL | Anielski D.,Max Planck Institute for Nuclear Physics | Anielski D.,PNSensor GmbH | Boll R.,Max Planck Advanced Study Group at CFEL | And 116 more authors.
International Conference on Ultrafast Structural Dynamics, ICUSD 2012 | Year: 2012

We present static and time-resolved photoelectron angular distributions of laser-aligned p-fluorophenylacetylene and OCS molecules photoionized by fs-FEL pulses. The results are a proof-of-principle for recording dynamic structural changes of a molecule during Coulomb explosion. © 2012 OSA. Source

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