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The fragmentation functions of quarks and gluons are measured in various three-jet topologies in Z decays from the full data set collected with the Delphi detector at the Z resonance between 1992 and 1995. The results at different values of transverse momentum-like scales are compared. A parameterization of the quark and gluon fragmentation functions at a fixed reference scale is given. The quark and gluon fragmentation functions show the predicted pattern of scaling violations. The scaling violation for quark jets as a function of a transverse momentum-like scale is in a good agreement with that observed in lower energy \\({\\rm e}^+{\\rm e}^-\\) annihilation experiments. For gluon jets it appears to be significantly stronger. The scale dependences of the gluon and quark fragmentation functions agree with the prediction of the DGLAP evolution equations from which the colour factor ratio \\(C_A/C_F\\) is measured to be:

An update of the searches for charginos and neutralinos in DELPHI is presented, based mainly on recent data collected at centre-of-mass energies of 161 GeV and 172 GeV. No signal is found. For a sneutrino with mass above 300 GeV/c2 and a mass difference between the chargino and the lightest neutralino above 10 GeV/c2, the lower limit at 95% confidence level on the chargino mass ranges from 84.3 GeV/c2 to the kinematical limit (86.0 GeV/c2), depending on the mixing parameters. The limit decreases for lower chargino-neutralino mass differences. The limit in the case of a light sneutrino is 67.6 GeV/c2, provided that that there is no light sneutrino with a mass within 10 GeV/c2 below the chargino mass. Upper limits on neutralino pair production cross-sections of about a picobarn are derived. The (μ,M2) domain excluded in the MSSM-GUT scenario is determined by combining the neutralino and chargino searches. These results imply a limit on the mass of the lightest neutralino which, for a heavy sneutrino, is constrained to be above 24.9 GeV/c2 for tanß >- 1. The search has also been extended to the case where the lightest neutralino is unstable and decays into a photon and a gravitino. imply a limit on the mass of the lightest neutralino which, for a heavy sneutrino, is constrained to be above 24.9 GeV/c2 for tanß >- 1. The search has also been extended to the case where the lightest neutralino is unstable and decays into a photon and a gravitino.

Data taken by DELPHI during the 1995 and 1996 LEP runs have been used to search for the supersymmetric partners of electron, muon and tau leptons and of top and bottom quarks. The observations are in agreement with standard model predictions. Limits are set on sfermion masses. Searches for long lived scalar leptons from low scale supersymmetry breaking models exclude stau masses below 55 GeV/c2 at the 95% confidence level, irrespective of the gravitino mass.

Muon pair production in the process \\(e^+e^-\\to e^+e^-\\mu^+\\mu^-\\) is studied using the data taken at LEP1 (\\(\\sqrt{s}\\simeq m_Z\\)) with the DELPHI detector during the years 1992-1995. The corresponding integrated luminosity is 138.5 pb\\(^{-1}\\). The QED predictions have been tested over the whole \\(Q^2\\) range accessible at LEP1 (from several GeV\\(^2/c^4\\) to several hundred GeV\\(^2/c^4\\)) by comparing experimental distributions with distributions resulting from Monte Carlo simulations using various generators. Selected events are used to extract the leptonic photon structure function \\(F_2^\\gamma\\). Azimuthal correlations are used to obtain information on additional structure functions, \\(F_A^\\gamma\\) and \\(F_B^\\gamma\\), which originate from interference terms of the scattering amplitudes. The measured ratios \\(F_A^\\gamma/F_2^\\gamma\\) and \\(F_B^\\gamma/F_2^\\gamma\\) are significantly different from zero and consistent with QED predictions.

Declines in eelgrass, an important and widespread coastal habitat, are associated with wasting disease in recent outbreaks on the Pacific coast of North America. This study presents a novel method for mapping and predicting wasting disease using Unoccupied Aerial Vehicle (UAV) with low‐altitude autonomous imaging of visible bands. We conducted UAV mapping and sampling in intertidal eelgrass beds across multiple sites in Alaska, British Columbia, and California. We designed and implemented a UAV low‐altitude mapping protocol to detect disease prevalence and validated against in situ results. Our analysis revealed that green leaf area index derived from UAV imagery was a strong and significant (inverse) predictor of spatial distribution and severity of wasting disease measured on the ground, especially for regions with extensive disease infection. This study highlights a novel, efficient, and portable method to investigate seagrass disease at landscape scales across geographic regions and conditions. Plain Language Summary Diseases of marine organisms are increasing in many regions worldwide, therefore, efficient time‐series monitoring is critical for understanding the dynamics of disease and examining its progression in time to implement management interventions. In the first study of its kind, we use high‐resolution Unoccupied Aerial Vehicle (UAV) imagery collected to detect disease at 12 sites across the North‐East Pacific coast of North America spanning 18 degrees of latitude. The low altitude UAV visible‐bands imagery achieved 1.5 cm spatial resolution, and analysis was performed at the seagrass leaf scale based on object‐oriented image analysis. Our findings suggest that drone mapping of coastal plants may substantially increase the scale of disease risk assessments in nearshore habitats and further our understanding of seagrass meadow spatial‐temporal dynamics. These can be scaled up by searching for environmental signals of the pathogen, for example, with surveillance of wastewater for signs of Covid in human populations. This application could easily apply to other areas to construct a high‐resolution monitoring network for seagrass conservation. Key Points First study using low‐altitude high‐resolution Unoccupied Aerial Vehicle (UAV) imagery to detect coastal seagrass disease The low altitude UAV mapping achieved 1.5 cm spatial resolution and the object‐oriented analysis were performed at the seagrass leaf scale Statistical validation against in situ sampling demonstrated reliable results to use drone imaging for coastal plants disease assessment

Topological states of matter exhibit fascinating physics combined with an intrinsic stability. A key challenge is the fast creation of topological phases, which requires massive reorientation of charge or spin degrees of freedom. Here we report the picosecond emergence of an extended topological phase that comprises many magnetic skyrmions. The nucleation of this phase, followed in real time via single-shot soft X-ray scattering after infrared laser excitation, is mediated by a transient topological fluctuation state. This state is enabled by the presence of a time-reversal symmetry-breaking perpendicular magnetic field and exists for less than 300 ps. Atomistic simulations indicate that the fluctuation state largely reduces the topological energy barrier and thereby enables the observed rapid and homogeneous nucleation of the skyrmion phase. These observations provide fundamental insights into the nature of topological phase transitions, and suggest a path towards ultrafast topological switching in a wide variety of materials through intermediate fluctuating states. Time-resolved X-ray scattering is utilized to demonstrate an ultrafast 300 ps topological phase transition to a skyrmionic phase. This transition is enabled by the formation of a transient topological fluctuation state.

A variety of mammals suppress reproduction when they experience poor physical condition or environmental harshness. In many marine mammal species, reproductive impairment has been correlated to polychlorinated biphenyls (PCBs), the most frequently measured chemical pollutants, while the relative importance of other factors remains understudied. We investigate whether reproductively active females abandon investment in their foetus when conditions are poor, exemplified using an extensively studied cetacean species; the harbour porpoise ( Phocoena phocoena ). Data on disease, fat and muscle mass and diet obtained from necropsies in The Netherlands were used as proxies of health and nutritional status and related to pregnancy and foetal growth. This was combined with published life history parameters for 16 other areas to correlate to parameters reflecting environmental condition: mean energy density of prey constituting diets (MEDD), cumulative human impact and PCB contamination. Maternal nutritional status had significant effects on foetal size and females in poor health had lower probabilities of being pregnant and generally did not sustain pregnancy throughout gestation. Pregnancy rates across the Northern Hemisphere were best explained by MEDD. We demonstrate the importance of having undisturbed access to prey with high energy densities in determining reproductive success and ultimately population size for small cetaceans.

Ecological communities are jointly structured by dispersal, density-independent responses to environmental conditions, and density-dependent biotic interactions. Metacommunity ecology provides a framework for understanding how these processes combine to determine community seagrass meadows along the British Columbia coast. We tested the hypothesis that eelgrass Zostera marina L. epifaunal invertebrate assemblages are influenced by local environmental conditions but that high dispersal rates at larger spatial scales dampen the effects of environmental differences. We used hierarchical joint species distribution modelling to understand the contribution of environmental conditions, spatial distance between meadows, and species co-occurrences to epifaunal invertebrate abundance and distribution across the region. We found that patterns of taxonomic compositional similarity among meadows were inconsistent with dispersal limitation, and meadows in the same region were often no more similar to each other than meadows over 1000 km away. Abiotic environmental conditions (temperature, dissolved oxygen) explained a small fraction of variation in taxonomic abundance patterns across the region. We found novel co-occurrence patterns among taxa that could not be explained by shared responses to environmental gradients, suggesting the possibility that interspecific interactions influence seagrass invertebrate abundance and distribution. Our results suggest that biodiversity and ecosystem functions provided by seagrass meadows reflect ecological processes occurring both within meadows and across seascapes and that management of eelgrass habitat for biodiversity may be most effective when both local and regional processes are considered.

Marine biodiversity is a key indicator of ecosystem health and can be assessed using a variety of methods, including environmental DNA (eDNA) sampling. However, the ecology of eDNA in physically dynamic nearshore environments remains uncertain, particularly with regards to how eDNA stratifies with depth. Here, we paired eDNA sampling with dive surveys at six sites in Knight Inlet, British Columbia, Canada. eDNA samples were collected from the surface, midwater column and bottom (8–25 m depth) at each site, while dive surveys focused on the bottom (benthic) habitat. Amplicon sequencing using the mitochondrial 12S rRNA gene (targeting fish) and the COI gene (targeting marine invertebrates and algae) resolved significant differences in community composition in surface waters compared with midwater and bottom. Differences by depth were greater than differences across sites, with surface waters dominated by salmon (Oncorhynchus spp.) and rotifer DNA, and midwater and bottom samples largely dominated by Pacific herring, copepods, and mussels. eDNA samples collected at the surface, therefore, may not accurately capture benthic communities, particularly in systems with high levels of freshwater input such as coastal temperate fjords. Over small spatial scales, particularly in systems with strong stratification, adding samples from different depths may be more effective at maximizing inferred diversity rather than sampling more sites. In general, there was low overlap in species detection between dive and eDNA surveys (less than 10% for each taxonomic group – fish, invertebrates, and algae). However, we observed clear strengths for each method – dive surveys provided better taxonomic resolution, while eDNA resolved greater total diversity. These results suggest that the two survey methods can be used in tandem to provide distinct and complementary snapshots of marine biodiversity in the nearshore environment. We examined the vertical stratification of eDNA in a fjord ecosystem as well as compared eDNA results with concurrent dive surveys. We found that surface eDNA communities were distinct from midwater and bottom, and dive surveys and eDNA sampling provided unique yet complimentary snapshots of biodiversity in the nearshore environment.