Image reconstruction in optoacoustic imaging is often based on a delay-and-sum (DAS) or a frequency domain (FD) algorithm. In this study, we performed a comprehensive comparison of these two algorithms together with coherence factor (CF) weighting using phantom and in-vivo mouse data obtained with optoacoustic microscopy. For this purpose we developed an FD based definition of the CF. Our results reveal the equivalence of DAS and FD, with and without CF weighting, in terms of spatial resolution and contrast-to-noise ratio (CNR) but highlight the clear advantage of FD in terms of computational cost, making it preferable for 3D reconstruction or real-time applications. An important additional result of this research is that, contradictory to previous studies, CF weighting does not lead to any improvement in lateral resolution.

Animal models have for long been pivotal for parasitology research. Over the last few years, techniques such as intravital, optoacoustic and magnetic resonance imaging, optical projection tomography, and selective plane illumination microscopy developed promising potential for gaining insights into host-pathogen interactions by allowing different visualization forms in vivo and ex vivo. Advances including increased resolution, penetration depth, and acquisition speed, together with more complex image analysis methods facilitate tackling biological problems previously impossible to study and/or quantify. Here we discuss advances and challenges in the in vivo imaging toolbox, which hold important potential for the field of parasitology. KeywordsParasitology, imaging, in vivo, animal models Imaging toolbox in parasitologyImaging techniques developed for biomedical applications have had an important impact in parasitology research. Such techniques include platforms developed to image host-pathogen interactions at various scales, ranging from molecules to whole organisms (summarised in table 1). These techniques have complementary advantages with respect to each other. This review focuses on the technological advances used for visualization of host-pathogen interactions either in vivo, or ex vivo in whole organisms in five imaging techniques: intravital microscopy (IVM), optical projection tomography (OPT), bioluminescence imaging, optoacoustic imaging (OAI), and magnetic resonance imaging (MRI). Advanced fluorescence methods applied to intravital microscopyIntravital microscopy (IVM) is a powerful technique to investigate dynamic cellular processes and host-parasite interactions within functioning organs. Organs studied by IVM in the context of parasitology include the brain [1][2][3][4], the skin [5][6][7], the placenta [8,9], the lungs [10], the liver [11][12][13], and the spleen [14,15] (summarized in table 2, green=IVM exists; yellow=organ relevant but IVM never done; grey = IVM not done). Important advances in parasitology have been achieved using wide-field epifluorescence, confocal, spinning disc, or two-photon IVM.Recent developments, which have expanded the applications of IVM include the generation of

We propose a GPU-accelerated implementation of frequency-domain synthetic aperture focusing technique (SAFT) employing truncated regularized inverse k-space interpolation. Our implementation achieves sub-1s reconstruction time for data sizes of up to 100 M voxels, providing more than a tenfold decrease in reconstruction time as compared to CPU-based SAFT. We provide an empirical model that can be used to predict the execution time of quasi-3D reconstruction for any data size given the specifications of the computing system.

Abstract. Stalagmites are natural archives containing detailed information on continental climate variability of the past. Microthermometric measurements of fluid inclusion homogenisation temperatures allow determination of stalagmite formation temperatures by measuring the radius of stable laser-induced vapour bubbles inside the inclusions. A reliable method for precisely measuring the radius of vapour bubbles is presented. The method is applied to stalagmite samples for which the formation temperature is known. An assessment of the bubble radius measurement accuracy and how this error influences the uncertainty in determining the formation temperature is provided. We demonstrate that the nominal homogenisation temperature of a single inclusion can be determined with an accuracy of ±0.25 • C, if the volume of the inclusion is larger than 10 5 µm 3 . With this method, we could measure in a proof-of-principle investigation that the formation temperature of 10-20 yr old inclusions in a stalagmite taken from the Milandre cave is 9.87 ± 0.80 • C, while the mean annual surface temperature, that in the case of the Milandre cave correlates well with the cave temperature, was 9.6 ± 0.15 • C, calculated from actual measurements at that time, showing a very good agreement. Formation temperatures of inclusions formed during the last 450 yr are found in a temperature range between 8.4 and 9.6 • C, which corresponds to the calculated average surface temperature. Paleotemperatures can thus be determined within ±1.0 • C. IntroductionIn recent years, stalagmites have gained growing interest in palaeoclimate research since they can provide long (up to several hundred thousand years), detailed and precisely dated records of past climate variability. In many cases cave air temperature is stable throughout the year and is closely related to the mean annual air temperature above the cave (McDermott, 2004;Fairchild et al., 2006). Assuming that the stalagmite formation temperature equals the cave air temperature, stalagmites can deliver well-dated and highly resolved palaeotemperature records.Until now, palaeoclimate information from stalagmites has mainly been obtained from stable isotope measurements of speleothem calcite (δ 18 O and δ 13 C), annual band thickness and trace element contents (Fairchild and Treble, 2009). These climate proxies can deliver qualitative records of climate variability, but a quantitative interpretation of the data still remains difficult. Uncertainties associated with the interpretation of the most widely used climate proxy, the δ 18 O signal, are caused by the lack of knowledge of the exact cave temperature. Furthermore, the δ 18 O signal can be influenced by other climatic factors such as precipitation and moisture source as well as by environmental factors in the epikarst and the cave. Thus, an independent temperature proxy would form the basis for a quantitative interpretation of the highresolution δ 18 O isotope records.Several quantitative temperature proxies have been used to determine stalagmite f...

Phthalocyanines are ideal candidates as photosensitizers for photodynamic therapy (PDT) of cancer due to their favorable chemical and photophysical properties. However, their tendency to form aggregates in water reduces PDT efficacy and poses challenges in obtaining efficient forms of phthalocyanines for therapeutic applications. In the current work, polyvinylpyrrolidone (PVP) and micellar formulations were compared for encapsulating and monomerizing a water-soluble zinc phthalocyanine bearing four non-peripheral triethylene glycol chains (Pc1). 1H NMR spectroscopy combined with UV–vis absorption and fluorescence spectroscopy revealed that Pc1 exists as a mixture of regioisomers in monomeric form in dimethyl sulfoxide but forms dimers in an aqueous buffer. PVP, polyethylene glycol castor oil (Kolliphor RH40), and three different triblock copolymers with varying proportions of polyethylene and polypropylene glycol units (termed P188, P84, and F127) were tested as micellar carriers for Pc1. 1H NMR chemical shift analysis, diffusion-ordered spectroscopy, and 2D nuclear Overhauser enhancement spectroscopy was applied to monitor the encapsulation and localization of Pc1 at the polymer interface. Kolliphor RH40 and F127 micelles exhibited the highest affinity for encapsulating Pc1 in the micellar core and resulted in intense Pc1 fluorescence emission as well as efficient singlet oxygen formation along with PVP. Among the triblock copolymers, efficiency in binding and dimer dissolution decreased in the order F127 > P84 > P188. PVP was a strong binder for Pc1. However, Pc1 molecules are rather surface-attached and exist as monomer and dimer mixtures. The results demonstrate that NMR combined with optical spectroscopy offer powerful tools to assess parameters like drug binding, localization sites, and dynamic properties that play key roles in achieving high host–guest compatibility. With the corresponding adjustments, polymeric micelles can offer simple and easily accessible drug delivery systems optimizing phthalocyanines’ properties as efficient photosensitizers.