Giant spin splitting of the two-dimensional electron gas at the surface of SrTiO3.

Two-dimensional electron gases (2DEGs) forming at the interfaces of transition metal oxides exhibit a range of properties, including tunable insulator-superconductor-metal transitions, large magnetoresistance, coexisting ferromagnetism and superconductivity, and a spin splitting of a few meV (refs 10, 11). Strontium titanate (SrTiO3), the cornerstone of such oxide-based electronics, is a transparent, non-magnetic, wide-bandgap insulator in the bulk, and has recently been found to host a surface 2DEG (refs 12-15). The most strongly confined carriers within this 2DEG comprise two subbands, separated by an energy gap of 90 meV and forming concentric circular Fermi surfaces. Using spin- and angle-resolved photoemission spectroscopy (SARPES), we show that the electron spins in these subbands have opposite chiralities. Although the Rashba effect might be expected to give rise to such spin textures, the giant splitting of almost 100 meV at the Fermi level is far larger than anticipated. Moreover, in contrast to a simple Rashba system, the spin-polarized subbands are non-degenerate at the Brillouin zone centre. This degeneracy can be lifted by time-reversal symmetry breaking, implying the possible existence of magnetic order. These results show that confined electronic states at oxide surfaces can be endowed with novel, non-trivial properties that are both theoretically challenging to anticipate and promising for technological applications.

Spin-orbital entanglement and the breakdown of singlets and triplets in Sr2RuO4 revealed by spin- and angle-resolved photoemission spectroscopy.

Spin-orbit coupling has been conjectured to play a key role in the low-energy electronic structure of Sr2RuO4. By using circularly polarized light combined with spin- and angle-resolved photoemission spectroscopy, we directly measure the value of the effective spin-orbit coupling to be 130±30 meV. This is even larger than theoretically predicted and comparable to the energy splitting of the dxy and dxz,yz orbitals around the Fermi surface, resulting in a strongly momentum-dependent entanglement of spin and orbital character in the electronic wavefunction. As demonstrated by the spin expectation value ⟨sk⃗·s-k⃗⟩ calculated for a pair of electrons with zero total momentum, the classification of the Cooper pairs in terms of pure singlets or triplets fundamentally breaks down, necessitating a description of the unconventional superconducting state of Sr2RuO4 in terms of these newly found spin-orbital entangled eigenstates.

Elemental topological insulator with tunable Fermi level: strained α-Sn on InSb(001).

We report on the epitaxial fabrication and electronic properties of a topological phase in strained α-Sn on InSb. The topological surface state forms in the presence of an unusual band order not based on direct spin-orbit coupling, as shown in density functional and GW slab-layer calculations. Angle-resolved photoemission including spin detection probes experimentally how the topological spin-polarized state emerges from the second bulk valence band. Moreover, we demonstrate the precise control of the Fermi level by dopants.

Fermi nesting between atomic wires with strong spin-orbit coupling.

The mutual interplay between superlattice structures, band filling factors, and spin-orbit coupling results in a highly correlated electronic spin and charge state found for an array of atomic Pb wires grown on Si(557). By means of spin- and angle-resolved photoemission spectroscopy, the spin texture close to the Fermi surface was found to be alternating and equidistant; thus, Fermi nesting occurs in between bands with the same spin helicity, giving rise to spin-polarized charge-density waves in the direction across the wires. An out-of-phase superposition of both Rashba channels is manifested by an extraordinary large Rashba splitting of Δk0=0.2 Å(-1)=g/2, where g is a reciprocal lattice vector defined by the interwire distance and fits into the model of spin-density waves in antiferromagnetically ordered chain structures. The implications towards spin-polarized transport along the wires will be discussed.

Large tunable Rashba spin splitting of a two-dimensional electron gas in Bi2Se3.

We report a Rashba spin splitting of a two-dimensional electron gas in the topological insulator Bi(2)Se(3) from angle-resolved photoemission spectroscopy. We further demonstrate its electrostatic control, and show that spin splittings can be achieved which are at least an order-of-magnitude larger than in other semiconductors. Together these results show promise for the miniaturization of spintronic devices to the nanoscale and their operation at room temperature.

Detection and management of an outbreak of equine herpesvirus type 1 infection and associated neurological disease in a veterinary teaching hospital.

BACKGROUND: Because of the serious disease sequelae associated with equine herpesvirus type 1 (EHV-1) infections, awareness and control measures used to control outbreaks are important issues for all horse populations. OBJECTIVES: Describe the occurrence and management of an outbreak of EHV-1 infection at a veterinary hospital. ANIMALS: Horses hospitalized at a referral veterinary hospital. METHODS: A horse with myeloencephalopathy associated with EHV-1 infection (EHM) was admitted for diagnostic evaluation and treatment under strict infection control procedures. We describe the occurrence and management of a nosocomial outbreak of EHV-1 infections associated with admission of this patient. RESULTS: Despite institution of rigorous biosecurity precautions at the time of admission of the index case, EHV-1 infections spread to 6 other horses that were hospitalized at the James L. Voss Veterinary Teaching Hopsital, including 2 that served as sources of infection for horses on their home premises after discharge. Infection with EHV-1 was confirmed by polymerase chain reaction (PCR) and by seroconversion documented by glycoprotein G ELISA. A voluntary quarantine was imposed and admissions were restricted to prevent additional horses from being exposed. Quarantine duration was abbreviated by serial testing of all horses with PCR. CONCLUSIONS AND CLINICAL IMPORTANCE: These findings illustrate the contagious disease risk that can accompany management of horses with EHM. Horses with active nasal EHV-1 shedding should be isolated in an airspace that is separate from other horses by strictly enforced biosecurity and isolation procedures. Serial testing with PCR may be a useful adjunct to determine when the risk of transmission has been minimized.

Seroprevalence and risk factors for canine H3N8 influenza virus exposure in household dogs in Colorado.

BACKGROUND: Since 2004, canine influenza virus (CIV) has spread throughout the United States. While studies suggest that CIV is commonly detected in shelter dogs, little is known about its prevalence in household dogs. OBJECTIVES: To evaluate the seroprevalence of CIV in pet dogs presented for care in a veterinary hospital in Colorado and to investigate risk factors that might predispose these dogs to CIV infection. ANIMALS: One hundred and forty dogs presenting to the Community Practice service, 110 dogs seen at other clinical services at Colorado State University's Veterinary Teaching Hospital in 2009, and samples from 75 dogs seen before 2004. METHODS: In this prospective study, samples were tested with hemagglutination inhibition assays, using 3 CIV isolates. To identify risk factors for CIV infection, 140 owners completed questionnaires at time of sampling. RESULTS: CIV seroprevalence was 2.9% (4/140) for dogs seen by the Community Practice service and 4.5% (5/110) for dogs seen by other hospital services (P=.48). All sera collected before 2004 tested negative for CIV. No differences were seen in antibody titers to the 3 CIV isolates tested. Data from the questionnaires indicated an association between CIV seropositivity and canine daycare visits (P<.001). CONCLUSION AND CLINICAL IMPORTANCE: CIV seropositivity in household dogs in Colorado is low, although it has increased since 2004. Antibody titers to the 3 CIV isolates were comparable, suggesting that measurable antigenic drift has not yet occurred. Finally, dogs boarded in kennels or attending daycare might be at an increased risk of CIV infection.

Observation of correlated spin-orbit order in a strongly anisotropic quantum wire system.

Quantum wires with spin-orbit coupling provide a unique opportunity to simultaneously control the coupling strength and the screened Coulomb interactions where new exotic phases of matter can be explored. Here we report on the observation of an exotic spin-orbit density wave in Pb-atomic wires on Si(557) surfaces by mapping out the evolution of the modulated spin-texture at various conditions with spin- and angle-resolved photoelectron spectroscopy. The results are independently quantified by surface transport measurements. The spin polarization, coherence length, spin dephasing rate and the associated quasiparticle gap decrease simultaneously as the screened Coulomb interaction decreases with increasing excess coverage, providing a new mechanism for generating and manipulating a spin-orbit entanglement effect via electronic interaction. Despite clear evidence of spontaneous spin-rotation symmetry breaking and modulation of spin-momentum structure as a function of excess coverage, the average spin polarization over the Brillouin zone vanishes, indicating that time-reversal symmetry is intact as theoretically predicted.

[Poisoning of horses by the bark of the false acacia (Robinia pseudoacacia)]. / Vergiftung bei Pferden durch die Rinde der "Falschen Akazie" (Robinia pseudoacacia).

The present study describes the poisoning due to Robinia pseudoacacia in two horses. One of the horses showed mainly intestinal symptoms such as decreased intestinal motility and obstipation of the pelvic flexure. In the second animal central nervous symptoms were predominant. It showed intermittent phases of somnolence alternating with phases of excitation and head pressing. In addition mydriasis and a lacking menace response could be observed. Sensation to the head and the spinal reflexes were reduced. Symptomatic treatment was initiated in both animals and recovery occurred within 2 days.

[Epidemiologic studies of the occurrence of bovine virus diarrhea/mucosal disease in 2892 cattle in 95 dairy farms]. / Epidemiologische Untersuchungen über das Vorkommen von BVD/MD bei 2892 Rindern in 95 Milchviehbetrieben.

Blood samples were collected from 2892 cows and heifers of various ages from 95 dairy farms in the Kanton of St. Gallen and were tested for antibodies against bovine virus diarrhea. The percentages of seropositive, seronegative and inconclusive cases were 83.7%, 13.0% and 3.3%, respectively. In all herds, at least one case was seropositive, and in 29% of the herds, all the animals tested were seropositive. On a herd basis, the seroprevalence ranged from 16.2% to 100% with a mean (+/- SD) of 85.8 +/- 17.6%. The seroprevalence in one to two-year-old heifers was not significantly different from that of the entire sample.

Epidemiology and ecology of H3N8 canine influenza viruses in US shelter dogs.

BACKGROUND: H3N8 canine influenza virus (CIV) infection might contribute to increased duration of shelter stay for dogs. Greater understanding of factors contributing to CIV within shelters could help veterinarians identify control measures for CIV. OBJECTIVES: To assess community to shelter dog CIV transmission, estimate true prevalence of CIV, and determine risk factors associated with CIV in humane shelters. ANIMALS: 5,160 dogs upon intake or discharge from 6 US humane shelters, December 2009 through January 2012. METHODS: A cross-sectional study was performed with prospective convenience sampling of 40 dogs from each shelter monthly. Nasal swabs and serum samples were collected. Hemagglutination inhibition and real-time reverse transcriptase-polymerase chain reaction assays were performed for each nasal and serum sample. True prevalence was estimated by stochastic latent class analysis. Logistic regression was used to identify risk factors associated with CIV shedding and seropositivity. RESULTS: Nasal swabs were positive from 4.4% of New York (NY), 4.7% of Colorado (CO), 3.2% of South Carolina, 1.2% of Florida, and 0% of California and Texas shelter dogs sampled. Seropositivity was the highest in the CO shelter dogs at 10%, and NY at 8.5%. Other shelters had 0% seropositivity. Information-theoretic analyses suggested that CIV shedding was associated with region, month, and year (model weight = 0.95) and comingling/cohousing (model weight = 0.92). CONCLUSIONS AND CLINICAL IMPORTANCE: Community dogs are a likely source of CIV introduction into humane shelters and once CIV has become established, dog-to-dog transmission maintains the virus within a shelter.

Direct observation of the spin texture in SmB6 as evidence of the topological Kondo insulator.

Topological Kondo insulators have been proposed as a new class of topological insulators in which non-trivial surface states reside in the bulk Kondo band gap at low temperature due to strong spin-orbit coupling. In contrast to other three-dimensional topological insulators, a topological Kondo insulator is truly bulk insulating. Furthermore, strong electron correlations are present in the system, which may interact with the novel topological phase. By applying spin- and angle-resolved photoemission spectroscopy, here we show that the surface states of SmB6 are spin polarized. The spin is locked to the crystal momentum, fulfilling time reversal and crystal symmetries. Our results provide strong evidence that SmB6 can host topological surface states in a bulk insulating gap stemming from the Kondo effect, which can serve as an ideal platform for investigating of the interplay between novel topological quantum states with emergent effects and competing orders induced by strongly correlated electrons.

Observation of a topological crystalline insulator phase and topological phase transition in Pb(1-x)Sn(x)Te.

A topological insulator protected by time-reversal symmetry is realized via spin-orbit interaction-driven band inversion. The topological phase in the Bi(1-x)Sb(x) system is due to an odd number of band inversions. A related spin-orbit system, the Pb(1-x)Sn(x)Te, has long been known to contain an even number of inversions based on band theory. Here we experimentally investigate the possibility of a mirror symmetry-protected topological crystalline insulator phase in the Pb(1-x)Sn(x)Te class of materials that has been theoretically predicted to exist in its end compound SnTe. Our experimental results show that at a finite Pb composition above the topological inversion phase transition, the surface exhibits even number of spin-polarized Dirac cone states revealing mirror-protected topological order distinct from that observed in Bi(1-x)Sb(x). Our observation of the spin-polarized Dirac surface states in the inverted Pb(1-x)Sn(x)Te and their absence in the non-inverted compounds related via a topological phase transition provide the experimental groundwork for opening the research on novel topological order in quantum devices.

[Equine motor neuron disease (EMND). A case report]. / Equine motor neuron disease (EMND). Ein Fallbericht.

A 13-year-old warmblood mare was presented because of progressive weight loss, general weakness and trembling. On examination the horse stood with its head lowered and the limbs placed under the body. On lifting its head spasms of the neck muscles could be observed. At the same time the horse developed trembling over the lower neck and muscle fasciculations continued over the whole body. Additional signs included frequent recumbency, polyphagia and facial hyperaesthesia. The horse showed no signs of ataxia. Haematology was normal. Blood biochemistry revealed slight increased aspartate aminotransferase (AST: 1060 U/I) and creatine kinase levels (CK: 441 U/I). Based on the clinical findings equine motor neuron disease was diagnosed. The horse was euthanatized due to poor prognosis and the progression of symptoms. The typical neurodegenerative changes found on histological examination of the spinal cord confirmed the diagnosis.