Influenza A Viruses in Whistling Ducks (Subfamily Dendrocygninae)

As compared to other Anseriformes, data related to influenza A virus (IAV) detection and isolation, and IAV antibody detection in whistling ducks (Dendrocygna spp. and Thalassornis leuconotus; subfamily Dendrocygninae) are limited. To better evaluate the potential role of whistling ducks in the epidemiology of IAV, we (1) conducted surveillance for IAV from black-bellied whistling ducks (BBWD, Dendrocygnaautumnalis) sampled in coastal Louisiana, USA, during February 2018 and 2019, and (2) reviewed the published literature and Influenza Resource Database (IRD) that reported results of IAV surveillance of whistling ducks. In the prospective study, from 166 BBWD sampled, one H10N7 IAV was isolated (0.6% prevalence), and overall blocking enzyme-linked immunosorbent assay (bELISA) antibody seroprevalence was 10%. The literature review included publications and data in the IRD from 1984 to 2020 that reported results from nearly 5000 collected samples. For any given collection, the IAV isolation rate never exceeded 5.5%, and seroprevalence estimates ranged from 0 to 42%. Results from our prospective study in Louisiana are consistent with this historic literature; however, although all data consistently demonstrated a low prevalence of infection, the potential role of this species in the epidemiology of IAV should not be totally discounted. In sum, whistling ducks can be infected with IAV, they represent important species on many areas where waterfowl winter, and their distribution across the globe appears to be changing.

Influenza A viruses remain infectious for more than seven months in northern wetlands of North America

In this investigation, we used a combination of field- and laboratory-based approaches to assess if influenza A viruses (IAVs) shed by ducks could remain viable for extended periods in surface water within three wetland complexes of North America. In a field experiment, replicate filtered surface water samples inoculated with duck swabs were tested for IAVs upon collection and again after an overwintering period of approximately 6-7 months. Numerous IAVs were molecularly detected and isolated from these samples, including replicates maintained at wetland field sites in Alaska and Minnesota for 181-229 days. In a parallel laboratory experiment, we attempted to culture IAVs from filtered surface water samples inoculated with duck swabs from Minnesota each month during September 2018-April 2019 and found monthly declines in viral viability. In an experimental challenge study, we found that IAVs maintained in filtered surface water within wetlands of Alaska and Minnesota for 214 and 226 days, respectively, were infectious in a mallard model. Collectively, our results support surface waters of northern wetlands as a biologically important medium in which IAVs may be both transmitted and maintained, potentially serving as an environmental reservoir for infectious IAVs during the overwintering period of migratory birds.

Influenza A Prevalence and Subtype Diversity in Migrating Teal Sampled Along the United States Gulf Coast

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 (Spatula discors) and American green-winged (Anas carolinensis) 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. During spring migration, 266 low pathogenicity (LP) IAV positive samples were recovered from 7547 paired cloacal-oropharyngeal (COP) samples (prevalence, 3.5%; annual range, 1.3%-8.4%). During fall migration, 650 LP IAV-positive samples were recovered from 9493 COP samples (prevalence, 6.8%; annual range, 0.4%-23.5%). Overall, 34 and 20 different IAV subtypes were recovered during fall and spring sampling, respectively. Consistent with previous results for fall migrating ducks, H3 and H4 hemagglutinin (HA) subtypes were most common; however, H4 subtype viruses predominated every year. This is in contrast to the predominance of LP H7 and H10 HA subtype viruses during spring. The N6 and N8 neuraminidase subtypes, which were usually associated with H4, were most common during fall; the N6 subtype was not recovered in the spring. These consistent seasonal trends in IAV subtype detection in teal are currently not understood and highlight the need for further research regarding potential drivers of spatiotemporal patterns of infection, such as population immunity.

Waterfowl occurrence and residence time as indicators of H5 and H7 avian influenza in North American Poultry

Avian influenza (AI) affects wild aquatic birds and poses hazards to human health, food security, and wildlife conservation globally. Accordingly, there is a recognized need for new methods and tools to help quantify the dynamic interaction between wild bird hosts and commercial poultry. Using satellite-marked waterfowl, we applied Bayesian joint hierarchical modeling to concurrently model species distributions, residency times, migration timing, and disease occurrence probability under an integrated animal movement and disease distribution modeling framework. Our results indicate that migratory waterfowl are positively related to AI occurrence over North America such that as waterfowl occurrence probability or residence time increase at a given location, so too does the chance of a commercial poultry AI outbreak. Analyses also suggest that AI occurrence probability is greatest during our observed waterfowl northward migration, and less during the southward migration. Methodologically, we found that when modeling disparate facets of disease systems at the wildlife-agriculture interface, it is essential that multiscale spatial patterns be addressed to avoid mistakenly inferring a disease process or disease-environment relationship from a pattern evaluated at the improper spatial scale. The study offers important insights into migratory waterfowl ecology and AI disease dynamics that aid in better preparing for future outbreaks.

Absence of a Large Superconductivity-Induced Gap in Magnetic Fluctuations of Sr_{2}RuO_{4}

Inelastic neutron scattering experiments on Sr_{2}RuO_{4} determine the spectral weight of the nesting induced magnetic fluctuations across the superconducting transition. There is no observable change at the superconducting transition down to an energy of ∼0.35  meV, which is well below the 2Δ values reported in several tunneling experiments. At this and higher energies magnetic fluctuations clearly persist in the superconducting state. Only at energies below ∼0.3  meV can evidence for partial suppression of spectral weight in the superconducting state be observed. This strongly suggests that the one-dimensional bands with the associated nesting fluctuations do not form the active, highly gapped bands in the superconducting pairing in Sr_{2}RuO_{4}.

Evidence for wild waterfowl origin of H7N3 influenza A virus detected in captive-reared New Jersey pheasants

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. The estimated time of the most recent common ancestry (TMRCA) between the pheasant virus and those most closely related from wild waterfowl was early 2013 for both the H7 HA and N3 NA gene segments. None of the viruses from waterfowl identified as being most closely related to A/pheasant/New Jersey/26996-2/2014 at the HA and NA gene segments in ML and MCC phylogenetic analyses shared ≥99 % nucleotide sequence identity for internal gene segment sequences. This result indicates that specific viral strains identified in this study as being closely related to the HA and NA gene segments of A/pheasant/New Jersey/26996-2/2014 were not the direct predecessors of the etiological agent identified during the New Jersey outbreak. However, the recent common ancestry of the H7 and N3 gene segments of waterfowl-origin viruses and the virus isolated from pheasants suggests that viral diversity maintained in wild waterfowl likely played an important role in the emergence of A/pheasant/New Jersey/26996-2/2014.

Correlated decay of triplet excitations in the Shastry-Sutherland compound SrCu2(BO3)2

The temperature dependence of the gapped triplet excitations (triplons) in the 2D Shastry-Sutherland quantum magnet SrCu(2)(BO(3))(2) is studied by means of inelastic neutron scattering. The excitation amplitude rapidly decreases as a function of temperature, while the integrated spectral weight can be explained by an isolated dimer model up to 10 K. Analyzing this anomalous spectral line shape in terms of damped harmonic oscillators shows that the observed damping is due to a two-component process: one component remains sharp and resolution limited while the second broadens. We explain the underlying mechanism through a simple yet quantitatively accurate model of correlated decay of triplons: an excited triplon is long lived if no thermally populated triplons are nearby but decays quickly if there are. The phenomenon is a direct consequence of frustration induced triplon localization in the Shastry-Sutherland lattice.

Optimizing Surveillance for South American Origin Influenza A Viruses Along the United States Gulf Coast Through Genomic Characterization of Isolates from Blue-winged Teal (Anas discors)

Relative to research focused on inter-continental viral exchange between Eurasia and North America, less attention has been directed towards understanding the redistribution of influenza A viruses (IAVs) by wild birds between North America and South America. In this study, we genomically characterized 45 viruses isolated from blue-winged teal (Anas discors) along the Texas and Louisiana Gulf Coast during March of 2012 and 2013, coincident with northward migration of this species from Neotropical wintering areas to breeding grounds in the United States and Canada. No evidence of South American lineage genes was detected in IAVs isolated from blue-winged teal supporting restricted viral gene flow between the United States and southern South America. However, it is plausible that blue-winged teal redistribute IAVs between North American breeding grounds and wintering areas throughout the Neotropics, including northern South America, and that viral gene flow is limited by geographical barriers further south (e.g., the Amazon Basin). Surveillance for the introduction of IAVs from Central America and northern South America into the United States may be further optimized through genomic characterization of viruses resulting from coordinated, concurrent sampling efforts targeting blue-winged teal and sympatric species throughout the Neotropics and along the United States Gulf Coast.

A magnetically shielded room with ultra low residual field and gradient

A versatile and portable magnetically shielded room with a field of (700 ± 200) pT within a central volume of 1 m × 1 m × 1 m and a field gradient less than 300 pT/m, achieved without any external field stabilization or compensation, is described. This performance represents more than a hundredfold improvement of the state of the art for a two-layer magnetic shield and provides an environment suitable for a next generation of precision experiments in fundamental physics at low energies; in particular, searches for electric dipole moments of fundamental systems and tests of Lorentz-invariance based on spin-precession experiments. Studies of the residual fields and their sources enable improved design of future ultra-low gradient environments and experimental apparatus. This has implications for developments of magnetometry beyond the femto-Tesla scale in, for example, biomagnetism, geosciences, and security applications and in general low-field nuclear magnetic resonance (NMR) measurements.

Quantum effects in a weakly frustrated s=1/2 two-dimensional heisenberg antiferromagnet in an applied magnetic field

We have studied the two-dimensional S=1/2 square-lattice antiferromagnet Cu(pz)_{2}(ClO4)_{2} (where pz denotes pyrazine), using neutron inelastic scattering and series expansion calculations. We show that the presence of antiferromagnetic next-nearest-neighbor interactions enhances quantum fluctuations associated with resonating valence bonds. Intermediate magnetic fields lead to a selective tuning of resonating valence bonds and a spectacular inversion of the zone-boundary dispersion, providing novel insight into 2D antiferromagnetism in the quantum limit.

Magnetic-field-induced soft-mode quantum phase transition in the high-temperature superconductor La1.855Sr0.145CuO4: an inelastic neutron-scattering study

Inelastic neutron-scattering experiments on the high-temperature superconductor La1.855Sr0.145CuO4 reveal a magnetic excitation gap Delta that decreases continuously upon application of a magnetic field perpendicular to the CuO2 planes. The gap vanishes at the critical field required to induce long-range incommensurate antiferromagnetic order, providing compelling evidence for a field-induced soft-mode driven quantum phase transition.

Field-induced paramagnons at the metamagnetic transition of Ca1.8Sr0.2RuO4

The magnetic excitations in Ca1.8Sr0.2RuO4 were studied across the metamagnetic transition and as a function of temperature using inelastic neutron scattering. At low temperature and low magnetic field the magnetic response is dominated by a complex superposition of incommensurate antiferromagnetic fluctuations. Upon increasing the magnetic field across the metamagnetic transition, paramagnon and finally well-defined magnon scattering is induced, partially suppressing the incommensurate signals. The high-field phase in Ca1.8Sr0.2RuO4, therefore, has to be considered as an intrinsically ferromagnetic state stabilized by the magnetic field.

Magnetic excitations in multiferroic TbMnO3: evidence for a hybridized soft mode

The magnetic excitations in multiferroic TbMnO3 have been studied by inelastic neutron scattering in the spiral and sinusoidally ordered phases. At the incommensurate magnetic zone center of the spiral phase, we find three low-lying magnons whose character has been fully determined using neutron-polarization analysis. The excitation at the lowest energy is the sliding mode of the spiral, and two modes at 1.1 and 2.5 meV correspond to rotations of the spiral rotation plane. These latter modes are expected to couple to the electric polarization. The 2.5 meV mode is in perfect agreement with recent infrared-spectroscopy data giving strong support to its interpretation as a hybridized phonon-magnon excitation.

Polarized intestinal hybrid cell lines derived from primary culture: establishment and characterization

A cell culture system has been developed that produces stable gastrointestinal (GI) polarized cell lines capable of maintaining hormone secretion. A spontaneously transformed rat mucosal epithelial cell was selected for hypoxanthine/guanine phosphoribosyltransferase deficiency and transfected with a plasmid conferring hygromycin resistance (BRIE 291 cells). Fusion of these cells with dispersed small intestinal epithelia cells resulted in hybrid cell lines that retained characteristic properties of the native GI cell more effectively than the transformed tumorigenic parental cell line. Hybrid hBRIE 380 cells are uniformly cuboidal with microvilli, contain villin, are contact inhibited, are anchorage dependent, require serum supplementation for growth, and are more sensitive to virus infection than the parental BRIE 291 cells. Fusion of BRIE 291 with dispersed pancreatic islet cells has resulted in a variety of pancreatic-hormone-producing cell lines. One of these, hybrid hBRIE 291-i2, forms confluent monolayers capable of synthesizing insulin-like immunoreactivity. These studies demonstrate that functionally polarized GI cells can be generated from primary cultures of nondividing committed epithelial cells by somatic cell hybridization and make feasible the selection and maintenance of specific GI epithelial cell types in confluent monolayer cultures.

Adjuvant radiation therapy in patients with detectable prostate specific antigen following radical prostatectomy

Adjuvant radiation therapy following radical prostatectomy for adenocarcinoma of the prostate was given to 25 patients. Of these patients 8 had microscopic lymph node metastasis, 8 had seminal vesicle invasion without positive lymph nodes, 6 had positive surgical margins and 3 had only capsule penetration. Their only evidence of residual disease was detectable serum prostate specific antigen (PSA) by the Yang assay. A total of 15 patients (60%) had a subsequent decrease in PSA to less than 0.3 ng./ml. and an additional 5 (20%) had a decrease in PSA by more than 50%. Currently 8 patients have no detectable PSA after a median followup of 18 months (17 to 38 months) since initiating radiation therapy. Only 1 of 12 patients with detectable PSA immediately after radical prostatectomy has had a durable response to adjuvant radiation therapy. In contrast 7 of 13 patients with a delayed increase in PSA had a durable response. The ability of adjuvant radiation therapy to eliminate serum PSA in patients with a delayed increase in PSA after radical prostatectomy is encouraging. However, longer followup, including the use of nonradiated control subjects, is needed to assess the ability of adjuvant radiation therapy to control local disease and prolong patient survival.