40 research outputs found
Spin-induced optical second harmonic generation in the centrosymmetric magnetic semiconductors EuTe and EuSe
Spectroscopy of the centrosymmetric magnetic semiconductors EuTe and EuSe
reveals spin-induced optical second harmonic generation (SHG) in the band gap
vicinity at 2.1-2.4eV. The magnetic field and temperature dependence
demonstrates that the SHG arises from the bulk of the materials due to a novel
type of nonlinear optical susceptibility caused by the magnetic dipole
contribution combined with spontaneous or induced magnetization. This
spin-induced susceptibility opens access to a wide class of centrosymmetric
systems by harmonics generation spectroscopy.Comment: 5 pages, 3 figures, submitted to PR
Potential mechanisms of attenuation for rifampicin-passaged strains of Flavobacterium psychrophilum
A multilocus sequence analysis scheme for characterization of Flavobacterium columnare isolates
A genome-wide association study in catfish reveals the presence of functional hubs of related genes within QTLs for columnaris disease resistance
A Review of Bacterial Co-Infections in Farmed Catfish: Components, Diagnostics, and Treatment Directions
Catfish production is a major aquaculture industry in the United States and is the largest sector of food fish production. As producers aim to optimize production yields, diseases caused by bacterial pathogens are responsible for high pond mortality rates and economic losses. The major bacterial pathogens responsible are Edwardsiella ictaluri, Aeromonas spp., and Flavobacterium columnare. Given the outdoor pond culture environments and ubiquitous nature of these aquatic pathogens, there have been many reports of co-infective bacterial infections within this aquaculture sector. Co-infections may be responsible for altering disease infection mechanics, increasing mortality rates, and creating difficulties for disease management plans. Furthermore, proper diagnoses of primary and secondary pathogens are essential in ensuring the correct treatment approaches for antimicrobials and chemical applications. A thorough understanding of the interactions and infectivity dynamics for these warm water bacterial pathogens will allow for the adoption of new prevention and control methods, particularly in vaccine development. This review aims to provide an overview of co-infective pathogens in catfish culture and present diagnostic case data from Mississippi and Alabama to define prevalence for these multiple-species infections better
Vertebrate mucus stimulates biofilm development and upregulates iron acquisition genes in Flavobacterium columnare
Optical third-harmonic spectroscopy of the magnetic semiconductor EuTe
EuTe possesses the centrosymmetric crystal structure m3m of rocksalt type in which the second-harmonic generation is forbidden in electric dipole approximation but the third-harmonic generation (THG) is allowed. We studied the THG spectra of this material and observed several resonances in the vicinity of the band gap at 2.2-2.5 eV and at higher energies up to 4 eV, which are related to four-photon THG processes. The observed resonances are assigned to specific combinations of electronic transitions between the ground 4f(7) state at the top of the valence band and excited 4f(6)5d(1) states of Eu(2+) ions, which form the lowest energy conduction band. Temperature, magnetic field, and rotational anisotropy studies allowed us to distinguish crystallographic and magnetic-field-induced contributions to the THG. A strong modification of THG intensity for the 2.4 eV band and suppression of the THG for the 3.15 eV band was observed in applied magnetic field. Two main features of the THG spectra were assigned to 5d(t(2g)) and 5d(e(g)) subbands at 2.4 eV and 3.15 eV, respectively. A microscopic quantum-mechanical model of the THG response was developed and its conclusions are in qualitative agreement with the experimental results.DFG - Deutsche Forschungsgemeinschaft[YA65/4-1]RFBR Russian Foundation for Basic ResearchFoNE of the European Science FoundationFAPESPCNPq(DAAD) Deutscher Akademischer Austausch Dienst, GermanyFWF (Vienna, Austria