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Assessing Lagrangian coherence in atmospheric blocking
Get PDFAtmospheric blocking exerts a major influence on mid-latitude atmospheric circulation and is known to be associated with extreme weather events. Previous work has highlighted the importance of the origin of air parcels that define the blocking region, especially with respect to non-adiabatic processes such as latent heating. So far, an objective method of clustering the individual Lagrangian trajectories passing through a blocking into larger and, more importantly, spatially coherent air streams has not been established. This is the focus of our study.
To this end, we determine coherent sets of trajectories, which are regions in the phase space of dynamical systems that keep their geometric integrity in time and can be characterized by robustness under small random perturbations. We approximate a dynamic diffusion operator on the available Lagrangian data and use it to cluster the trajectories into coherent sets. Our implementation adapts the existing methodology to the non-Euclidean geometry of Earth's atmosphere and its challenging scaling properties. The framework also allows for statements about the spatial behavior of the trajectories as a whole. We discuss two case studies differing with respect to season and geographic location.
The results confirm the existence of spatially coherent feeder air streams differing with respect to their dynamical properties and, more specifically, their latent heating contribution. Air streams experiencing a considerable amount of latent heating (warm conveyor belts) occur mainly during the maturing phase of the blocking and contribute to its stability. In our example cases, trajectories also exhibit an altered evolution of general coherence when passing through the blocking region, which is in line with the common understanding of blocking as a region of low dispersion
Variational quantum algorithm for enhanced continuous variable optical phase sensing
Get PDFVariational quantum algorithms (VQAs) are hybrid quantum-classical approaches used for tackling a wide range of problems on noisy intermediate-scale quantum (NISQ) devices. Testing these algorithms on relevant hardware is crucial to investigate the effect of noise and imperfections and to assess their practical value. Here, we implement a variational algorithm designed for optimized parameter estimation on a continuous variable platform based on squeezed light, a key component for high-precision optical phase estimation. We investigate the ability of the algorithm to identify the optimal metrology process, including the optimization of the probe state and measurement strategy for small-angle optical phase sensing. Two different optimization strategies are employed, the first being a gradient descent optimizer using Gaussian parameter shift rules to estimate the gradient of the cost function directly from the measurements. The second strategy involves a gradient-free Bayesian optimizer, fine-tuning the system using the same cost function and trained on the data acquired through the gradient-dependent algorithm. We find that both algorithms can steer the experiment towards the optimal metrology process. However, they find minima not predicted by our theoretical model, demonstrating the strength of variational algorithms in modelling complex noise environments, a non-trivial task
Insect immunity in the Anthropocene
Get PDFAnthropogenic activities result in global change, including climate change, landscape degradation and pollution, that can alter insect physiology and immune defences. These changes may have contributed to global insect decline and the dynamics of insect-transmitted diseases. The ability of insects to mount immune responses upon infection is crucial for defence against pathogens and parasites. Suppressed immune defences reduce fitness by causing disease-driven mortality and elevated immune responses reduce energy available to invest in other fitness traits such as reproduction. Understanding the impact of anthropogenic factors on insect–pathogen interactions is therefore key to determining the contribution of anthropogenic global change to pathogen-driven global insect decline and the emergence and transmission of insect-borne diseases. Here, we synthesise evidence of the impact of anthropogenic factors on insect immunity. We found evidence that anthropogenic factors, such as insecticides and heavy metals, directly impacting insect immune responses by inhibiting immune activation pathways. Alternatively, factors such as global warming, heatwaves, elevated CO2 and landscape degradation can indirectly reduce insect immune responses via reducing the energy available for immune function. We further review how anthropogenic factors impact pathogen clearance and contribute to an increase in vector-borne diseases. We discuss the fitness cost of anthropogenic factors via pathogen-driven mortality and reduced reproductive output and how this can contribute to species extinction. We found that most research has determined the impact of a single anthropogenic factor on insect immune responses or pathogen resistance. We recommend studying the combined impact of multiple stressors on immune response and pathogen resistance to understand better how anthropogenic factors affect insect immunity. We conclude by highlighting the importance of initiatives to mitigate the impact of anthropogenic factors on insect immunity, to reduce the spread of vector-borne diseases, and to protect vulnerable ecosystems from emerging diseases
Die Saugbehandlung nach Klapp bei der Arthritis purulenta des Kiefergelenks des Pferdes
Get PDFDigitalisat der Ausgabe von 1912, erschienen 202
Quantifying Fire‐Driven Dust Emissions Using a Global Aerosol Model
Get PDFVegetation fires have become increasingly recognized as a potential entrainment mechanism for mineral dust. However, the global importance of this emission pathway remains largely unknown. Based on previous LES investigations, we developed a parameterization that relates the dust emission potential of wildfires to observational data of the fire radiative power and further soil‐surface conditions. It was implemented into the aerosol‐climate model ICON‐HAM and simulations with and without the new emission pathway were conducted for the 10‐year period 2004–2013. Fire‐dust emissions can account for around 230 (190–255) Tg yr −1 , which represents around 18 (15–21) % of the total global dust emissions. These additional emissions originate largely from regions that are typically not known as significant sources of mineral dust. Locally, wildfires can enhance the presence of atmospheric dust particles and on the Southern hemisphere might even surpass other forms of dust emission. Highly dust active fire regions are identified in areas where burning grasslands create suitable emission conditions together with emissive soil types despite rather weak fires, for example, in Eastern Europe or the Central US. Fire‐dust emissions are subject to a strong seasonal cycle, mainly driven by the fire activity, following the hemispheric warm and dry seasons. Multi‐year comparisons with (dust) AOD observations revealed improvements due to the additional fire‐dust emissions, particularly in the most fire‐active regions on the Southern hemisphere. Nevertheless, further research and improvements of the parameterization are required to better classify the source areas and their variation with the changing climate and land use conditions
Chemotherapeutische Versuche bei experimenteller Trypanosomiasis der Rinder
No full textDigitalisat der Ausgabe von 1912, erschienen 202
Separating the albedo-reducing effect of different light-absorbing particles on snow using deep learning
Get PDFSeveral different types of light-absorbing particles (LAPs) darken snow surfaces, enhancing snowmelt on glaciers and snowfields. LAPs are often present as a mixture of biotic and abiotic components at the snow surface, yet methods to separate their respective abundance and albedo-reducing effects are lacking. Here, we present a new optimisation method enabling the retrievals of dust, black carbon, and red algal abundances and their respective darkening effects from spectral albedo. This method includes a deep-learning emulator of a radiative transfer model (RTM) and an inversion algorithm. The emulator alone can be used as a fast and lightweight alternative to the full RTM with the possibility to add new features, such as new light-absorbing particles. The inversion method was applied to 180 ground field spectra collected on snowfields in southern Norway, with a mean absolute error on spectral albedo of 0.0056, and surface parameters that closely matched expectations from qualitative assessments of the surface. The emulator predictions of surface parameters were used to quantify the albedo-reducing effect of algal blooms, mineral dust, and dark particles represented by black carbon. Among these 180 surfaces, the albedo reduction due to light-absorbing particles was highly variable and reached up to 0.13, 0.21, and 0.25 for red algal blooms, mineral dust, and dark particles respectively. In addition, the effect of a single LAP was attenuated by the presence of other LAPs by up to 2–3 times. These results demonstrate the importance of considering the individual types of light-absorbing particles and their concomitant interactions for forecasting snow albedo
Feministische Archäologie und das Erbe von James Scott: Interventionen in die Geschichtsschreibung von Frauen
No full textAt the time of working on this paper (December 2024), I attended a session organized by Bidar Research Institution in Tehran, where a young feminist was presenting the results of her M.A. dissertation on the Iranian women’s movement, One Million Signatures Campaign, in the 2000s. When I questioned the application of theories developed to study the agency and political action of subaltern groups, particularly Asef Bayat’s work, one member of the audience responded that this is not relevant to feminism and women’s movement. Nobody provided a counter argument, but a young male student mentioned another work by Bayat, Post-Islamism: The Changing Faces of Political Islam, where he discusses the agency of ordinary women in the Iranian post-revolutionary society. He briefly discussed the relevance of Bayat’s work to the exploration of women as a subaltern group. In Life as Politics: How Ordinary People Change the Middle East, Asef Bayat (2010) introduces the quiet encroachment of the ordinary. Drawing on James Scott’s everyday forms of resistance, Bayat discusses how subaltern groups such as the poor and women seek “life chances” through quiet encroachment in daily life in post-revolutionary Iran. He claims that “in many authoritarian Muslim states, such as the Islamic Republic of Iran, where conservative Islamic laws are in place, women have become second-class citizens in many domains of public life. Consequently, a central question for women’s rights activists is how to achieve gender equality under such circumstances” (Bayat 2010: 96). Bayat answers this question in the framework of Scott’s theory: “Women resisted these policies, not much by deliberate organized campaigns, but largely through mundane daily practices in public domains, such as working, playing sports, studying, showing interest in art and music, or running for political offices” (Bayat 2010: 97). Bayat calls this “feminism of everyday life” (2010: 96). This short narrative brings me to the point that I want to discuss in this paper: the application of theories of political action and the resistance of subordinate groups in feminist and gender archaeology. I briefly discuss the relevance of subaltern studies generally and James Scott’s “everyday forms of resistance,” then turn to the methodological and socio-political outcomes of this expansion for feminist and gender archaeology. Finally, I discuss two examples to demonstrate the significance of daily life as a site of conflict and resistance
The Contentious Politics of the South Korean Anti-LGBT Movement
Get PDF'Opposing Desires' delves deeply into the contentious practices of the South Korean anti-LGBT movement, investigating its roots, framing strategies, transnational ties, and political endeavors. In times of right-wing populists gaining traction worldwide, this case study offers new insights into the cunning ways conservative Christians engage in both continuous and dynamic action forms to gain societal and political hegemony. Sociologists, political scientists and practitioners alike will discover how this dynamic continuity runs like a thread through anti-LGBT politics in Korea, displaying not just another far-right success story, but unveiling also contradictions and internal conflicts
Das Mitteldarmepithel der Insektenlarven während der Häutung
Get PDFDigitalisat der Ausgabe von 1911, erschienen 202