Publications by authors named "Patrick Walther"

Article Synopsis
  • - The study explores the relationship between migratory waterfowl and avian influenza (AI), highlighting how wild birds can influence AI outbreaks in commercial poultry across North America.
  • - Researchers used advanced statistical modeling techniques to analyze data from satellite-marked waterfowl, revealing that longer residency and higher presence of these birds increase the likelihood of AI occurring in poultry during northward migrations.
  • - Findings emphasize the importance of considering different spatial scales when studying wildlife and disease interactions, as misinterpreting data can lead to incorrect conclusions about disease dynamics and risk factors.
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Wild birds in the order Anseriformes are important reservoirs for influenza A viruses (IAVs); however, IAV prevalence and subtype diversity may vary by season, even at the same location. To better understand the ecology of IAV during waterfowl migration through the Gulf Coast of the United States (Louisiana and Texas), surveillance of blue-winged () and American green-winged () teal was conducted. The surveillance was done annually during the spring (live capture; 2012-17) and fall (hunter harvested; 2007-17) at times inferred to coincide with northward and southward movements, respectively, for these waterfowl species.

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A dual catalytic setup based on N-heterocyclic olefins (NHOs) and magnesium bis(hexamethyldisilazide) (Mg(HMDS) ) was used to prepare poly(propylene oxide) with a molar mass (M ) >500 000 g mol , in some cases even >10  g mol , as determined by GPC/light scattering. This is achieved by combining the rapid polymerization characteristics of a zwitterionic, Lewis pair type mechanism with the efficient epoxide activation by the Mg species. Transfer-to-monomer, traditionally frustrating attempts at synthesizing polyethers with a high degree of polymerization, is practically removed as a limiting factor by this approach.

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Lewis pair polymerization employing -Heterocyclic olefins (NHOs) and simple metal halides as co-catalysts has emerged as a useful tool to polymerize diverse lactones. To elucidate some of the mechanistic aspects that remain unclear to date and to better understand the impact of the metal species, computational methods have been applied. Several key aspects have been considered: (1) the formation of NHO-metal halide adducts has been evaluated for eight different NHOs and three different Lewis acids, (2) the coordination of four lactones to MgCl₂ was studied and (3) the deprotonation of an initiator (butanol) was investigated in the presence and absence of metal halide for one specific Lewis pair.

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In August 2014, a low-pathogenic H7N3 influenza A virus was isolated from pheasants at a New Jersey gamebird farm and hunting preserve. In this study, we use phylogenetic analyses and calculations of genetic similarity to gain inference into the genetic ancestry of this virus and to identify potential routes of transmission. Results of maximum-likelihood (ML) and maximum-clade-credibility (MCC) phylogenetic analyses provide evidence that A/pheasant/New Jersey/26996-2/2014 (H7N3) had closely related H7 hemagglutinin (HA) and N3 neuraminidase (NA) gene segments as compared to influenza A viruses circulating among wild waterfowl in the central and eastern USA.

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Blue-winged teal (Anas discors) are abundant, small-bodied dabbling ducks that breed throughout the prairies of the northcentral USA and central Canada and that winter in the southern USA and northern Neotropics. Given the migratory tendencies of this species, it is plausible that blue-winged teal may disperse avian pathogens, such as parasites causing avian malaria, between spatially distant areas. To test the hypothesis that blue-winged teal play a role in the exchange of blood parasites between North America and areas further south, we collected information on migratory tendencies of this species and sampled birds at spatially distant areas during breeding and non-breeding periods to diagnose and genetically characterize parasitic infections.

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Seasonal dynamics of influenza A viruses (IAVs) are driven by host density and population immunity. Through an analysis of subtypic data for IAVs isolated from Blue-winged Teal (Anas discors), we present evidence for seasonal patterns in the relative abundance of viral subtypes in spring and summer/autumn.

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