Rabies is an important zoonotic disease with high fatality rates in animals and humans. In the Arctic, the Arctic fox (Vulpes lagopus) is regarded as the principal reservoir, but there is considerable debate about how the disease persists at the low population densities that are typical for this species. We describe an outbreak of rabies among Arctic foxes and Svalbard reindeer (Rangifer tarandus platyrhynchus) during 2011-12 on the remote Arctic archipelago of Svalbard, an area with a very low and relatively stable Arctic fox density.
View Article and Find Full Text PDFPrion diseases are progressive and fatal, neurodegenerative disorders described in humans and animals. According to the "protein-only" hypothesis, the normal host-encoded prion protein (PrP) is converted into a pathological and infectious form (PrP) in these diseases. Transgenic knockout models have shown that PrP is a prerequisite for the development of prion disease.
View Article and Find Full Text PDFThe objective of our study was to assess effects of pasteurization of milk and group size on the prevalence of diarrhea and daily growth in organic pre-weaned calves. Our study was conducted in six organic dairy herds where 353 pre-weaned calves were randomly placed in groups of two or four calves from one week of age. Three herds used pasteurized milk in a first five-month period and un-pasteurized milk in a second five-month period and three herds used unpasteurized in the first and pasteurized in the second period.
View Article and Find Full Text PDFDiarrhea and respiratory disease are major health problems for dairy calves, often causing calf mortality. Previous studies have found calf mortality to be higher in organic dairy herds compared to conventional herds. The aim of this study was to investigate the association between production system (conventional/organic), season (summer/winter) and calf mortality risk, diarrhea, signs of respiratory disease and ocular discharge, respectively, for dairy heifer calves aged 0-180 days.
View Article and Find Full Text PDFThe cellular prion protein PrP is highly expressed in neurons, but also present in non-neuronal tissues, including the testicles and spermatozoa. Most immune cells and their bone marrow precursors also express PrP. Clearly, this protein operates in highly diverse cellular contexts.
View Article and Find Full Text PDFA naturally occurring mutation in the gene of Norwegian dairy goats terminates synthesis of the cellular prion protein (PrP), rendering homozygous goats () devoid of the protein. Although PrP has been extensively studied, particularly in the central nervous system, the biological role of PrP remains incompletely understood. Here, we examined whether loss of PrP affects the initial stage of lipopolysaccharide (LPS)-induced acute lung injury (ALI).
View Article and Find Full Text PDFA resonant cavity method is presented which can measure loss tangents and dielectric constants for materials with dielectric constant from 150 to 10 000 and above. This practical and accurate technique is demonstrated by measuring barium strontium zirconium titanate bulk ferroelectric ceramic blocks. Above the Curie temperature, in the paraelectric state, barium strontium zirconium titanate has a sufficiently low loss that a series of resonant modes are supported in the cavity.
View Article and Find Full Text PDFThe cellular prion protein (PrPC) has been extensively studied because of its pivotal role in prion diseases; however, its functions remain incompletely understood. A unique line of goats has been identified that carries a nonsense mutation that abolishes synthesis of PrPC. In these animals, the PrP-encoding mRNA is rapidly degraded.
View Article and Find Full Text PDFBackground: The cellular prion protein (PrP) is an evolutionary conserved protein abundantly expressed not only in the central nervous system but also peripherally including the immune system. A line of Norwegian dairy goats naturally devoid of PrP (PRNP ) provides a novel model for studying PrP physiology.
Methods: In order to explore putative roles for PrP in acute inflammatory responses, we performed a lipopolysaccharide (LPS, Escherichia coli O26:B6) challenge of 16 goats (8 PRNP and 8 PRNP ) and included 10 saline-treated controls (5 of each PRNP genotype).
Background: Sepsis is a serious health problem associated with a range of infectious diseases in animals and humans. Early events of this syndrome can be mimicked by experimental administration of lipopolysaccharides (LPS). Compared with mice, small ruminants and humans are highly sensitive to LPS, making goats valuable in inflammatory models.
View Article and Find Full Text PDFThe physiological role of the cellular prion protein (PrP(C)) is incompletely understood. The expression of PrP(C) in hematopoietic stem cells and immune cells suggests a role in the development of these cells, and in PrP(C) knockout animals altered immune cell proliferation and phagocytic function have been observed. Recently, a spontaneous nonsense mutation at codon 32 in the PRNP gene in goats of the Norwegian Dairy breed was discovered, rendering homozygous animals devoid of PrP(C).
View Article and Find Full Text PDFGeneral expressions for the signals in frequency-modulation spectroscopy (FMS) appear in the literature but are often reduced to simple analytical equations following the assumption of a weak modulation index. This is little help to the experimentalist who wants to predict signals for modulation depths of the order of unity or greater, where strong FMS signals reside. Here, we develop general formulas for FMS signals in the case of an absorber with a Voigt line shape and then link these expressions to an example and existing numerical code for the line shape.
View Article and Find Full Text PDFCollagen type III glomerulopathy, also known as collagenofibrotic glomerulopathy, is a rare renal disease of unknown pathogenesis. The disease occurs in humans and animals and is characterized by massive glomerular accumulations of collagen type III. In the present study, we describe a Drever dog litter affected by an early onset variant of this glomerular disease, where 4 of 9 puppies developed renal failure within 50 days of age.
View Article and Find Full Text PDFPolarization is one of the basic properties of electromagnetic waves conveying valuable information in signal transmission and sensitive measurements. Conventional methods for advanced polarization control impose demanding requirements on material properties and attain only limited performance. We demonstrated ultrathin, broadband, and highly efficient metamaterial-based terahertz polarization converters that are capable of rotating a linear polarization state into its orthogonal one.
View Article and Find Full Text PDFWe present the design, numerical simulations and experimental measurements of terahertz metamaterial absorbers with a broad and flat absorption top over a wide incidence angle range for either transverse electric or transverse magnetic polarization depending on the incident direction. The metamaterial absorber unit cell consists of two sets of structures resonating at different but close frequencies. The overall absorption spectrum is the superposition of individual components and becomes flat at the top over a significant bandwidth.
View Article and Find Full Text PDFWe demonstrate the broadening of fundamental resonance in terahertz metamaterial by successive insertion of metal rings in the original unit cell of a split ring resonator (SRR) forming an inter connected nested structure. With the subsequent addition of each inner ring, the fundamental resonance mode shows gradual broadening and blue shift. For a total of four rings in the structure the resonance linewidth is enhanced by a factor of four and the blue shift is as large as 316 GHz.
View Article and Find Full Text PDFWe experimentally and numerically study the nature of coupling between laterally paired terahertz metamaterial split-ring resonators. Coupling is shown to modify the inductive-capacitive (LC) resonances resulting in either red or blue-shifting. Results indicate that tuning of the electric and magnetic coupling parameters may be accomplished not by changing the orientation or density of SRRs, but by a design modification at the unit cell level.
View Article and Find Full Text PDFWe present spatially resolved measurements of the electric field of terahertz pulses undergoing optical tunneling that show strong pulse reshaping in both time and space. This reshaping is shown to be a result of frequency and incidence-angle filtering of the complex amplitude of the plane-wave basis set that makes up the pulse. This filtering leads to spreading of the pulse in the time and space dimensions, as expected from linear dispersion theory.
View Article and Find Full Text PDFSpatiotemporal measurements of a near-single-cycle terahertz pulse emitted from a photoconductive switch terahertz (THz) source show the effects of spherical aberration and surface waves on the pulse shape. The measured phase front has a swallow-tail shape described by catastrophe theory that contributes to the concentric ring structure of THz beam profiles. A time-of-flight model shows that the pulse shape is due to propagation along a cusp caustic and enhancement of the wings of the swallow-tail pulse is caused by surface waves.
View Article and Find Full Text PDFPhys Rev E Stat Nonlin Soft Matter Phys
September 2001
We report time-domain measurements with subpicosecond resolution of optical tunneling of terahertz electromagnetic pulses undergoing frustrated total internal reflection. Measurements of the transmitted electromagnetic pulses over a 3 THz bandwidth permits direct determination of frequency-dependent phase and amplitude changes in both the thin and opaque barrier limits in a single measurement. A complex frequency response function describing propagation through the barrier is developed based upon linear dispersion theory and the Fresnel coefficients at complex angles in the optical barrier.
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