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Seeking TOA SW flux closure over semi-synthetic 3D cloud fields: exploring the accuracy of two angular distribution models
No full textTo accurately estimate outgoing top-of-atmosphere (TOA) shortwave (SW) fluxes from measurements of broadband radiances, angular distribution models (ADMs) are necessary. ADMs rely on radiance-predicting models that are trained on hemispherically-resolved CERES TOA radiance observations. The estimation of SW fluxes is particularly challenging for cloudy skies due to clouds' anisotropy, which substantially varies with their optical properties for any given sun-object-observer geometry. The aim of this study is to investigate the influence of micro- and macrophysical properties of liquid clouds on SW fluxes estimated by ADMs that are based on a semi-physical model and compare to operational ADMs. We hypothesize that a microphysically aware ADM performs better in observation angles influenced by single-scattering features. The semi-physical approach relies on a parameterized asymmetry parameter gΔ, which depends on the cloud effective radius and, after adjustments during training of the model, explicitly varies with sun–observer geometry. We link these adjustments to single scattering features, such as the shift of the cloud bow and glory with varying cloud droplet sizes. For the investigation, 125 3D cloud scenes are constructed based on observational data and theoretical assumptions. Using a Monte Carlo model, the TOA broadband SW radiances and fluxes of the semi-synthetic cloud scenes are simulated for different scenarios with varying viewing angles ( θv) along the principal plane and solar angles ( θs). Based on the resulting 20 000 scenarios, the sensitivity and accuracy of the two SW radiance-to-irradiance conversion approaches to cloud droplet size, spatial distribution of liquid water path, and mean optical thickness are quantified. The study emphasizes that explicitly including the liquid droplet effective radius in ADM generation can improve the accuracy of shortwave flux estimates. Particularly for viewing geometries that exhibit single scattering phenomena, such as cloud glory and cloud bow, flux estimates can benefit from microphysically aware ADMs. For the analyzed scenarios, we found that the errors of instantaneous TOA SW flux estimates could be reduced by up to 25 W m −2 . For scenes with very large or small droplets, the median error was reduced by up to 7 W m −2
Use of quantitative computed tomography for therapy planning and therapy monitoring in interventional pulmonary emphysema therapy
No full textDie irreversible Überblähung pulmonaler Alveolen wird als Lungenemphysem bezeichnet. Ursächlich ist bei der überwältigenden Mehrheit der Patienten vieljähriges inhalatives Tabakrauchen. Da keine kausale Therapie des Lungenemphysems existiert, ist der wichtigste Behandlungsansatz die Ausschaltung der ursächlichen Noxe, also ein konsequenter Rauchverzicht. Wenn alle konservativen Therapieoptionen ausgereizt sind, kann bei Patienten mit besonders fortgeschrittenem Lungenemphysem und hochgradiger obstruktiver Respirationsstörung eine (palliative) Lungenvolumenreduktion erwogen werden. Durch die Verkleinerung der Lunge soll sich einerseits die Atemmechanik verbessern und andererseits sollen sich komprimierte Lungenareale mit erhaltenem gesunden Lungenparenchym wieder besser entfalten können. Die in den 2020er Jahren am besten erforschte und am weitesten verbreitete minimalinvasive Technik ist die bronchoskopische Einlage endobronchialer Einbahnstraßen-Ventile in die Segmentbronchien eines zuvor ausgewählten Ziellappens (engl. endobronchial valves, EBV). Diese Ventile lassen Atemluft aus dem behandelten Lungenlappen zwar entweichen, sollen den Rückstrom von Luft aber verhindern und dadurch das Volumen des behandelten Lungenlappens sukzessive verringern. Die Auswahl des Ziellappens ist essentiell für den Behandlungserfolg. Einerseits sollen diejenigen Lungenareale mit der schwersten emphysematischen Destruktion verkleinert werden, wohingegen gesundes Lungenparenchym erhalten werden soll. Andererseits gefährden funktionelle Kurzschlussverbindungen im Sinne von Luftfisteln zwischen benachbarten Lungenlappen den Behandlungserfolg, was als „Kollaterale Ventilation“ (engl. collateral ventilation, CV) bezeichnet wird.
Quantitative Computertomographie (CT) ist ein unverzichtbares Werkzeug für die Planung und Therapiekontrolle einer EBV-Therapie. Aus lückenlos aufgezeichneten Volumendatensätzen der Lunge lassen sich mit geeigneten Softwares dreidimensionale Lungenmodelle berechnen, an denen volumetrische und densitometrische Messungen durchgeführt werden können. Dadurch ist es sowohl möglich, das Volumen und den prozentualen Emphysemanteil („Emphysemindex“) jedes Lungenlappens einzeln zu berechnen, als auch die vollständige Anlage der Interlobärspalten zu überprüfen, weil die sog. „Fissurenintegrität“ Hinweise auf das Vorliegen von CV liefert. Obwohl die ELVR mit EBV mittlerweile ein anerkanntes Routineverfahren mit Kostenübernahme durch die gesetzlichen Krankenversicherer ist, kommt es immer noch zu häufig vor, dass nach einer EBV-Implantation der erwartete Behandlungserfolg ausbleibt. Die vorgestellten Originalarbeiten erfolgten deshalb sämtlich mit dem Ziel, die aus der quantitativen CT-Analyse gewonnenen Informationen zu validieren und sie bestmöglich bei der Planung und Kontrolle der EBV-Therapie einzusetzen.
Zwei Originalarbeiten hatten eine verbesserte Patientenselektion zum Ziel und befassten sich deshalb mit der Identifikation präinterventioneller CT-Parameter, die mit gutem Behandlungserfolg einer EBV-Therapie korrelierten. Zwei weitere Originalarbeiten hatten ein besseres Verständnis der Zusammenhänge zwischen quantitativer Computertomographie und spirometrischer Lungenfunktionsuntersuchung zum Ziel. Wenn Komplikationen auftreten oder der Behandlungserfolg ausbleibt, sollten EBV bronchoskopisch entfernt werden. Originalarbeit 5 befasste sich als eine der ersten Studien überhaupt mit den Nachwirkungen einer erfolglosen EBV-Therapie. Zusammenfassend ist die in dieser Arbeit thematisierte quantitative CT-Analyse längst als Standardverfahren in Therapieplanung und Therapiemonitoring interventioneller Lungenemphysemtherapie etabliert. Einige unserer Originalarbeiten dazu haben sich mittlerweile überholt, andere sollten in Studien mit größerer Fallzahl validiert werden
Operando Study of the Active Phase in Liquid GaPt Alloy Catalysts
No full textThe operando study investigates propane dehydrogenation (PDH) using a liquid gallium-platinum catalyst based on the supported catalytically active liquid metal solutions (SCALMS) concept. The focus is on monitoring and analyzing the active phase during reaction using near-ambient pressure X-ray photoelectron spectroscopy (NAPXPS) combined with gas phase analysis. This approach proves practical in tracking surface changes and chemical states during catalytic reactions, providing real-time insights into the catalyst behavior. PDH, an industrially significant reaction, is investigated using a GaPt SCALMS with 1 at.% Pt content. The findings reveal that metallic liquid GaPt SCALMS exhibit high activity, while the presence of oxygen in the feed stream significantly lowers the activity of the catalyst. While current liquid metal catalysts often experience an activation period, a pathway to achieving stable conversion rates right after the start is demonstrated. This stability lays a foundation for developing next-generation catalysts with improved performance. The investigation also highlights the critical influence of oxidic Ga on catalytic activity, offering valuable guidance for optimizing catalyst design. Overall, the findings underscore the practical importance of NAPXPS in advancing the understanding of surface properties in catalytic systems
Unprecedented Formation of a Formally Cu(III) Trifluoromethyl Hydroxide Tetramer
No full textAerobic copper-mediated oxidative processes play a pivotal role in the context of enzymatic oxidation and catalysis. Herein, the first high-valent copper(III) trifluoromethyl hydroxide with the tetrameric heterocubane structure [Cu(CF3)2(OH)]4 was synthesized by air oxidation of copper(I) in the presence of TMSCF3/KF and fully characterized, including X-ray crystallography. This unique compound displays versatile reactivity, functioning as a hydroxide base in neutralization reactions with acids, which affords a broad variety of high-valent Cu(III) complexes with two trifluoromethyl groups. The synthetic relevance of copper(III) trifluoromethyl hydroxide for boronic acid trifluoromethylation was demonstrated. The natural population analysis (NPA) charge distribution in the tetrameric heterocubane was studied by DFT calculations, which support the experimentally observed behavior of this compound as a weak hydroxide base, and revealed the positive NPA charge of +1.157 on high-valent copper
Physiologically Motivated Sequential Population Modeling of Albumin Trends and Vedolizumab Pharmacokinetics for Pregnancy Dosing Regimen Optimization
No full textThe pharmacokinetics (PK) of monoclonal antibodies (mAbs) during pregnancy remains poorly characterized, despite active inflammatory bowel diseases (IBD) being the greatest risk factor for adverse pregnancy outcomes. To quantify pregnancy-induced changes, vedolizumab concentrations from 39 pregnant patients on various dosing regimens were analyzed using a sequential albumin-trend/PK modeling approach, extending a published vedolizumab non-pregnancy model. Albumin trends were first characterized using a polynomial mixed-effect model. Then, individual changes in albumin from their pre-pregnancy concentrations, implemented as time-varying patient-influential factor (covariate) in the PK model, served as potential biomarker of pregnancy-induced plasma volume expansion. The modeling framework allowed model-informed imputation of missing covariate data, extraction of hemodilution effect, and estimation of pre-pregnancy PK parameters. Due to albumin change, the central volume of distribution increased 52.4%, consistent with known gestational plasma volume expansion, while clearance increased to 38.6%. An additional third-trimester effect of gestational age, potentially reflecting transplacental transfer, increased clearance by an additional 33.3 percentage points. These changes led to a 49.5% decline in vedolizumab trough concentrations (Cmin) by late pregnancy. To maintain efficacious pre-pregnancy exposure (dependent on the individual dosing interval), dosing intervals were gradually shortened for approximately one-third (e.g., to up to 5.6 weeks for pre-pregnancy 8-week regimens). Optimized dosing times were summarized in an easy-to-use nomogram-like plot. This work provides the first population PK model of vedolizumab in pregnancy. By integrating physiologically motivated pregnancy effects, it advanced quantitative understanding of mAbs PK in pregnancy with potential application to other biologics and provides optimized dosing strategies to mitigate risks of adverse pregnancy outcomes
HiRISE mosaic of the northern delta of Jezero Crater, Mars
No full textThe mosaic comprises four HiRISE (High Resolution Imaging Science Experiment, McEwen et al., 2007) images: ESP_035141_1990_RED, ESP_037330_1990_RED, ESP_037607_1990_RED and PSP_002743_1985_RED.
Individual images were co-registered to a single CTX (Context Camera) ortho-image scene G12_022957_1985_XN_18N282W (5 m/pixel) (Malin et al., 2007), which was itself co-registered to the HRSC Mars Chart (HMC_13E10) ortho-rectified image mosaic (12.5 m/pixel) (Gwinner et al., 2016). Co-registration was performed using the “Georeferencing” tool in ArcGIS software with manually selected control points and spline transformations.
Following co-registration, brightness normalization was applied to harmonize the individual HiRISE images with the reference CTX image, thereby eliminating albedo discontinuities at image boundaries and achieving a visually homogeneous mosaic. Each HiRISE scene was subdivided into a grid of 12 × 36 patches (x-direction × y-direction), and the average brightness was calculated for each patch along with the corresponding patch from the reference CTX image. A normalization ratio for each patch was computed by dividing the reference brightness value by the original image brightness value. Transitions between patches were interpolated to eliminate visible boundary effects. Finally, the normalized images were mosaicked using standard GDAL command-line tools. The brightness adjustment algorithm was implemented in Python
On Loss Functionals for Physics-Informed Neural Networks for Steady-State Convection-Dominated Convection-Diffusion Problems
No full textSolutions of convection-dominated convection-diffusion problems usually possess layers, which are regions where the solution has a steep gradient. It is well known that many classical numerical discretization techniques face difficulties when approximating the solution to these problems. In recent years, physics-informed neural networks (PINNs) for approximating the solution to (initial-)boundary value problems ((I)BVPs) received a lot of interest. This paper studies various loss functionals for PINNs that are especially designed for convection-dominated convection-diffusion problems and that are novel in the context of PINNs. They are numerically compared to the vanilla and an hp-variational loss functional from the literature based on two steady-state benchmark problems whose solutions possess different types of layers. We observe that the best novel loss functionals reduce the L2(Omega) error by 17.3% for the first and 5.5% for the second problem compared to the methods from the literature
Full Crystallographic Imaging of Hexagonal Boron Nitride Monolayers with Phonon-Enhanced Sum-Frequency Microscopy
No full textHexagonal boron nitride (hBN) is an important 2D material for van der Waals heterostructures, single photon emitters, and infrared nanophotonics. The optical characterization of mono- and few-layer samples of hBN however, remains a challenge as the material is almost invisible optically. Here, phase-resolved sum-frequency microscopy is introduced as a technique for imaging monolayers of hBN grown by chemical vapor deposition (CVD) and visualizing their crystal orientation. Femtosecond mid-infrared (IR) and visible laser pulses are used for sum-frequency generation (SFG), which is imaged in a wide-field optical microscope. The IR laser resonantly excites a phonon of hBN that leads to an ≈800-fold enhancement of the SFG intensity, making it possible to image large 100 × 100 µm2 sample areas in less than 1 s. Heterodyne detection combined with azimuthal sample rotation further provides full crystallographic information. Combined knowledge of topography and crystal orientation reveals that triangular domains of CVD-grown monolayer hBN have nitrogen-terminated zigzag edges. Overall, SFG microscopy is an ultra-sensitive tool with the potential to image crystal structure, strain, stacking sequences, and twist angles in a wide range of van der Waals structures, where locating and identifying monolayer regions and interfaces with broken inversion symmetry is of paramount importance
Neuroticism is associated with increased amygdala connectivity to hippocampal and prefrontal regions during emotional face processing
No full textNeuroticism, a stable personality trait marked by heightened negative affect and emotional volatility, is a well-established transdiagnostic risk factor for internalizing psychopathology. While early research emphasized amygdala hyperreactivity as a core neural correlate, emerging evidence suggests that neuroticism may be more accurately characterized by dysfunctional connectivity between the amygdala and broader regulatory networks involved in emotion processing and cognitive control.
In this cross-sectional fMRI study, 115 healthy adults completed a classification task involving negative emotional facial expressions. Neuroticism was assessed using a latent factor score derived from five validated self-report instruments. Brain activity and psychophysiological interaction analyses were conducted using both region-of-interest and whole-brain approaches. Associations between neural measures and neuroticism were tested using robust regression, controlling for age and sex.
No evidence was found for an association between neuroticism and regional brain activity. However, higher neuroticism was associated with increased task-dependent functional connectivity between the amygdala and both the hippocampus and dorsolateral prefrontal cortex. Whole-brain analyses further revealed associations between neuroticism and amygdala coupling with regions implicated in emotion regulation and salience processing, including the anterior insula and dorsal cingulate cortex.
These findings support the conceptualization of neuroticism as a network-level phenomenon, characterized by dysregulated interactions within fronto-limbic and salience circuits, rather than by localized changes in brain activity. Specifically, increased amygdala-hippocampal and amygdala-prefrontal connectivity may underlie the persistence and regulation difficulties of negative emotions that characterize the neurotic phenotype
