Relationship among blood indicators of lipomobilization and hepatic function during early lactation in high-yielding dairy cows

Blood indicators are used as a tool to diagnose metabolic disorders. The present work was conducted to study the relationships among blood indicators of lipomobilization and hepatic function in high-yielding dairy cows. Two groups of Holstein cows were studied: 27 early lactation cows and 14 mid lactation cows from four different herds with similar husbandry characteristics in Galicia, Spain. Blood samples were obtained to measure beta-hydroxybutyrate (BHB), non-esterified fatty acids (NEFA), triglycerides (TG), and the activity of aspartate transaminase (AST) and gamma-glutamyl transferase. Cows in early lactation had higher levels of BHB and NEFA than mid lactation cows. High lipomobilization (NEFA > 400 µmol/L) was detected in 67% and 7% of early lactation and mid lactation cows, respectively, while subclinical ketosis (BHB > 1.2 mmol/L) was detected in 41% and 28% of the early lactation and lactation cows, respectively. TG concentrations were low in all cows suffering subclinical ketosis and in 61% of the cows with high lipomobilization. During early lactation, 30% of cows suffered hepatic lipidosis as detected by levels of AST. Compromised hepatic function was observed in early lactation cows as shown by lower concentrations of glucose, total protein, and urea

PtyNAMi: ptychographic nano-analytical microscope

Ptychographic X-ray imaging at the highest spatial resolution requires an optimal experimental environment, providing a high coherent flux, excellent mechanical stability and a low background in the measured data. This requires, for example, a stable performance of all optical components along the entire beam path, high temperature stability, a robust sample and optics tracking system, and a scatter-free environment. This contribution summarizes the efforts along these lines to transform the nanoprobe station on beamline P06 (PETRA III) into the ptychographic nano-analytical microscope (PtyNAMi

Beach litter sources around Nuuk, Greenland: An analysis by UArctic summer school graduate course students

Modeling studies illustrate the potential for long-range transport of plastics into the Arctic, although the degree to which this occurs remains relatively undocumented. We utilised a teaching exercise at a UArctic summer school graduate course in Nuuk, Greenland to conduct a preliminary in-depth analysis of beach litter sources in the Nuup Kangerlua fjord. Students and instructors collected and analysed 1800 litter items weighing 200 kg from one location in the fjord and another at its mouth. The results suggest a predominance of local sources to macrolitter, rather than long-range transport from Europe. Fisheries-related items and rope were common. Packaging which could be identified was largely suspected to be products distributed in Greenland, and soft plastics, which rarely disperse far from its source, were also common. The results suggest local measures to reduce mismanaged waste and emissions from fisheries are important for reducing marine litter in West Greenland.publishedVersio

Development and study of refractive phase retrieval and X-ray multibeam ptychography

The advent of phase retrieval techniques has increased the resolution in X-ray microscopy by nearly an order of magnitude. With conventional imaging, X-ray microscopes cannot reach their full potential due to the lack of strong focusing options for X-rays. While the wavelength of X-rays is a thousand times smaller than visible light, the resolution of X-ray microscopes is only ten times smaller than the resolution of light microscopes. Phase retrieval algorithms are not limited by the numerical aperture of the focusing optics and can therefore resolve much smaller features.Conventional phase retrieval algorithms reconstruct the complex transmission function of the sample. Most microscopic samples are nearly transparent for X-rays and are only visible through their phase contrast. The phase shift however is 2π periodic, which means a specific phase value cannot be distinguished from another one that is larger or smaller by 2π. This phenomenon is called phase wrapping and is problematic for samples that have a maximum phase shift of more than 2π. Phase unwrapping algorithms aim to solve these ambiguities, but are not always successful, because phase wraps can lead to artefacts and phase singularities during the phase retrieval. Phase wrapping is especially challenging for tomography, because the wrapped phase is not a simple projection and also not proportional to the sample density.In this thesis, new algorithms are developed that reconstruct the projected refractive index of the sample instead of the complex transmission. The projected refractive index is in a trivial way directly proportional to the refractive index of the sample. In contrast to the phase of the transmission function, the projected refractive index requires no phase unwrapping, as it is not limited to a specific range. This thesis presents three refractive algorithms for three widely used phase retrieval techniques: ptychography, holography and coherent diffractive imaging. All three refractive algorithms are demonstrated and evaluated on simulated data sets, in the case of refractive ptychography also on two experimental data sets. Refractive ptychography and refractive holography surpass conventional algorithms for samples with a phase shift of more than 2π. In the case of refractive coherent diffractive imaging, the new algorithm surpasses the conventional one even for samples with no phase wrapping.In the second part of this thesis, a new method to scan large samples is presented. Due to the long scan times, large samples are problematic to measure with scanning techniques such as ptychography. To scan large samples in a shorter time, Bevis et al. have developed multibeam ptychography, a technique that uses multiple simultaneous beams [Ultramicroscopy, 184, 164 (2018)]. This thesis presents a set-up for X-ray multibeam ptychography that allows arbitrary numbers and geometries of multibeams. This is made possible through the use of a lens array manufactured with two-photon lithography. The lens array is evaluated for a two and a six beam geometry using experimental data. Compared to a single beam, the multibeam set-up scans the same area up to three times faster

Ptychographic reconstruction with object initialization

X-ray ptychography is a cutting edge imaging technique providing ultra-high spatial resolutions. In ptychography, phase retrieval, i.e., the recovery of a complex valued signal from intensity-only measurements, is enabled by exploiting a redundancy of information contained in diffraction patterns measured with overlapping illuminations. For samples that are considerably larger than the probe we show that during the iteration the bulk information has to propagate from the sample edges to the center. This constitutes an inherent limitation of reconstruction speed for algorithms that use a flat initialization. Here, we experimentally demonstrate that a considerable improvement of computational speed can be achieved by utilizing a low resolution sample wavefront retrieved from measured diffraction patterns as object initialization. In addition, we show that this approach avoids phase artifacts associated with large phase gradients and may alleviate the requirements on phase structure within the probe. Object initialization is computationally fast, potentially beneficial for bulky sample and compatible with flat samples. Therefore, the presented approach is readily adaptable with established ptychographic reconstruction algorithms implying a wide spread use