Photoemission Circular Dichroism and Spin Polarization of the Topological Surface States in Ultrathin Bi2Te3 Films

Circular dichroism (CD) observed by photoemission, being sensitive to the orbital and spin angular momenta of the electronic states, is a powerful probe of the nontrivial surface states of topological insulators, but the experimental results thus far have eluded a comprehensive description. We report a study of Bi2Te3 films with thicknesses ranging from one quintuple layer (two-dimensional limit) to 12 layers (bulk limit) over a wide range of incident photon energy. The data show complex variations in magnitude and sign reversals, which are nevertheless well described by a theoretical calculation including all three photoemission mechanisms: dipole transition, surface photoemission, and spin-orbit coupling. The results establish the nontrivial connection between the spin-orbit texture and CD.

Improving global environmental management with standard corporate reporting

Multinational corporations play a prominent role in shaping the environmental trajectory of the planet. The integration of environmental costs and benefits into corporate decision-making has enormous, but as yet unfulfilled, potential to promote sustainable development. To help steer business decisions toward better environmental outcomes, corporate reporting frameworks need to develop scientifically informed standards that consistently consider land use and land conversion, clean air (including greenhouse gas emissions), availability and quality of freshwater, degradation of coastal and marine habitats, and sustainable use of renewable resources such as soil, timber, and fisheries. Standardization by itself will not be enough--also required are advances in ecosystem modeling and in our understanding of critical ecological thresholds. With improving ecosystem science, the opportunity for realizing a major breakthrough in reporting corporate environmental impacts and dependencies has never been greater. Now is the time for ecologists to take advantage of an explosion of sustainability commitments from business leaders and expanding pressure for sustainable practices from shareholders, financial institutions, and consumers.

Preserving knee function following osteoarthritis diagnosis: a sustainability theory and social ecology clinical commentary

To sustain natural systems, there must be an ongoing balance between environmental, social, and economic considerations. A key element of sustainability theory is to identify the most vulnerable surroundings. The most vulnerable knee tissue is the articular cartilage as it is the last line of osteoarthritis (OA) defense. This tissue has a poor capacity for healing. Based on sustainability theory and social ecology concepts we propose that several key factors contribute to knee function preservation. Factors include health history, genetic predisposition, personal behaviors, and socio-environmental factors in addition to local-regional-global physiological system function. Addressing only some of these factors or any one factor in isolation may lead to less than optimal treatment effectiveness. The purpose of this commentary is to introduce a medical, surgical and rehabilitation management approach for patients with knee OA that considers more than physical function improvement. This approach also considers social, emotional, and environmental factors to better ensure patient satisfaction, fulfilled expectations and successful outcomes. A clinical care pathway is presented for a 57-year-old patient with medial compartment knee OA who is contemplating early arthroplasty versus a knee function preservation treatment approach. Early arthroplasty refers to high revision likelihood based on a minimum 15 year prosthesis life-expectancy.

The association of flushing bother, impact, treatment satisfaction and discontinuation of niacin therapy

BACKGROUND

Niacin has lipid-modifying efficacy and cardiovascular benefit, but is underutilised because of niacin-induced flushing (NIF). This real-world, prospective, observational study characterised the severity and impact of NIF symptoms among participants who were newly prescribed extended-release (ER) niacin.

METHODS

Participants were surveyed daily during week 1 of therapy, at weeks 5, 9, 13, and at months 7, 10 and 13. Surveys included the Flushing Symptom Questionnaire (FSQ), which includes the Global Flushing Severity Score (GFSS) question, the Flushing Impact Questionnaire (FIQ) and the Treatment Satisfaction Questionnaire for Medication (TSQM).

RESULTS

Overall, 306 participants were enrolled. During week 1, 30.0% of participants reported a maximum GFSS ≥ 4 (moderate or greater). Mean FIQ domain scores increased with increasing flushing severity, primarily driven by the Irritation/Frustration domain. By week 13, only 2.5% of participants had attained a 2 g ER niacin dose. By month 13, 43.5% (n = 133) had discontinued ER niacin. At discontinuation, only 3.1% of participants had attained the 2 g dose. Over half of the participants who discontinued experienced flushing symptoms: 82% reported moderate to extreme flushing (GFSS ≥ 4), and 68% reported severe to extreme flushing (GFSS ≥ 7). Participants who discontinued and had flushing side effects reported high degrees of impact in the FIQ Irritation/Frustration domain, and high dissatisfaction as a result of side effects, as measured by the TSQM.

CONCLUSION

In a real-world setting, NIF side effects were bothersome and had an impact on the continuation of therapy.

Eddy viscosity in dense granular flows

We present a seminal set of experiments on dense granular flows in the stadium shear geometry. The advantage of this geometry is that it produces steady shear flow over large deformations, in which the shear stress is constant. The striking result is that the velocity profiles exhibit an S shape, and are not linear as local constitutive laws would predict. We propose a model that suggests this is a result of wall perturbations which span through the system due to the nonlocal behavior of the material. The model is analogous to that of eddy viscosity in turbulent boundary layers, in which the distance to the wall is introduced to predict velocity profiles. Our findings appear pivotal in a number of experimental and practical situations involving dense granular flows next to a boundary. They could further be adapted to other similar materials such as dense suspensions, foams, or emulsions.

Short communication: Streptococcus species isolated from mastitis milk samples in Germany and their resistance to antimicrobial agents

Mastitis is one of the most frequent infectious diseases in dairy cattle and is a reason for antimicrobial drug usage in dairy cows. The bacteria involved in bovine mastitis are mainly Streptococcus spp., Staphylococcus spp., and coliforms. The aim of this study was to determine antimicrobial resistance among Streptococcus spp. isolated from bovine mastitis milk. Antimicrobial resistance in Strep. uberis (n=227), Strep. dysgalactiae (n=49), and Strep. agalactiae (n=3) was determined for 9 antimicrobial agents using the broth microdilution method in accordance with Clinical and Laboratory Standards Institute recommendations. Of all Streptococcus spp., 13% were multidrug resistant. The rate of multidrug resistance was higher among Strep. uberis (15%) than among Strep. dysgalactiae (6%) and Strep. agalactiae (0%). Resistance to tetracycline was the most common, followed by resistance to erythromycin, pirlimycin, and gentamicin. Resistance rates were higher on farms with more than 80 cows compared with those with fewer than 20 cows. β-Lactams should remain the drugs of choice in the treatment of streptococcal mastitis. The slightly elevated minimum inhibitory concentrations determined for these antibiotics may indicate, however, the emergence of resistant streptococci. To identify such changes in susceptibility as early as possible, antimicrobial resistance in streptococci should be surveyed regularly.

SDF-1 in myocardial repair

Stem cell therapy for the prevention and treatment of cardiac dysfunction holds significant promise for patients with ischemic heart disease. Excitingly early clinical studies have demonstrated safety and some clinical feasibility, while at the same time studies in the laboratory have investigated mechanisms of action and strategies to optimize the effects of regenerative cardiac therapies. One of the key pathways that has been demonstrated critical in stem cell-based cardiac repair is (stromal cell-derived factor-1) SDF-1:CXCR4. SDF-1:CXCR4 has been shown to affect stem cell homing, cardiac myocyte survival and ventricular remodeling in animal studies of acute myocardial infarction and chronic heart failure. Recently released clinical data suggest that SDF-1 alone is sufficient to induce cardiac repair. Most importantly, studies like those on the SDF-1:CXCR4 axis have suggested mechanisms critical for cardiac regenerative therapies that if clinical investigators continue to ignore will result in poorly designed studies that will continue to yield negative results.

Illuminating the surface spin texture of the giant-Rashba quantum-well system Bi/Ag(111) by circularly polarized photoemission

We have mapped out the spin texture of a Bi/Ag surface alloy prepared on a thin Ag film by circularly polarized angle-resolved photoemission spectroscopy. A term proportional to ∇·A in the interaction Hamiltonian gives rise to strong surface photoexcitation, which interferes with a Rashba contribution to yield a pronounced circular dichroic effect in Bi/Ag. The dipole transition, often taken to be the only important photoexcitation mechanism, is actually negligible. A parameter-free calculation yields a dichroic pattern in excellent agreement with experiment.

Interfacial protection of topological surface states in ultrathin Sb films

Spin-polarized gapless surface states in topological insulators form chiral Dirac cones. When such materials are reduced to thin films, the Dirac states on the two faces of the film can overlap and couple by quantum tunneling, resulting in a thickness-dependent insulating gap at the Dirac point. Calculations for a freestanding Sb film with a thickness of four atomic bilayers yield a gap of 36 meV, yet angle-resolved photoemission measurements of a film grown on Si(111) reveal no gap formation. The surprisingly robust Dirac cone is explained by calculations in terms of interfacial interaction.

IVI epoprostenol as salvage therapy in pulmonary arterial hypertension: an Australian perspective

BACKGROUND

IVI epoprostenol is the only therapy for pulmonary arterial hypertension (PAH) with a randomized controlled trial demonstrating improved survival, when used as first-line monotherapy. In Australia it is used as salvage therapy for those failing treatment with other targeted therapies or presenting in World Health Organization functional class (FC) IV.

AIMS

Report experience with IVI epoprostenol, administered as salvage therapy for the treatment of adults with PAH in a single Australian PAH centre.

METHODS

Retrospective case series of all patients commenced on IVI epoprostenol for PAH, between 2002 and 2010. Review of case notes with collection of data at baseline and after treatment, including FC, 6-min walk test (6MWT), right ventricular systolic pressure (RVSP) on echocardiogram, patient survival and treatment complications. Change in indices was assessed using the Wilcoxon Sign Rank Test and is expressed as median (inter-quartile range).

RESULTS

A total of 23 patients was included. Treatment was generally well tolerated with few major complications. At the end of the study period, nine patients were successfully bridged to transplant, five had a sustained response to IVI epoprostenol, six had an incomplete response but were clinically stabilized, two died awaiting transplant and one died who was not a candidate for transplantation. Overall, when measured at best level post initiation of IVI epoprostenol, there were significant improvements in FC -1 [0 to -1] (P < 0.0001), 6MWT (m) +117 [70-264] (P= 0.002) and RVSP (mmHg) -7.0 [4.0 to -45] (P= 0.03).

CONCLUSION

Findings support efficacy of epoprostenol as salvage therapy for patients with PAH.

Fragility of surface states and robustness of topological order in Bi2Se3 against oxidation

Topological surface states are protected against local perturbations, but this protection does not extend to chemical reaction over the whole surface, as demonstrated by theoretical studies of the oxidation of Bi(2)Se(3) and its effects on the surface spin polarization and current. While chemisorption of O(2) largely preserves the topological surface states, reaction with atomic O removes the original surface states and yields two new sets of surface states. One set forms a regular Dirac cone but is topologically trivial. The other set, while topologically relevant, forms an unusual rounded Dirac cone. The details are governed by the hybridization interaction at the interface.

Looking for better health in all the wrong places: the road to "equality" hits a dead end

The actual evidence base for measures of health inequality among the elderly in the United States remains rather thin. Addressing the real causes of health inequalities will require measuring what matters, accounting for the time lags and non-health-care factors behind the development of future health conditions and outcomes, and setting better priorities and targets. An early intervention strategy should focus more on future generations of elderly Americans when they are young.

Human adenovirus-vectored foot-and-mouth disease vaccines: establishment of a vaccine product profile through in vitro testing

Next generation, foot-and-mouth disease (FMD) molecular vaccines based on replication deficient human adenovirus serotype 5 viral vectored delivery of FMD capsid genes (AdFMD) are being developed by the United States Dept. of Homeland Security and industry partners. The strategic goal of this program is to develop AdFMD licensed vaccines for the USA National Veterinary Stockpile for use, if needed, as emergency response tools during an FMD outbreak. This vaccine platform provides a unique opportunity to develop a set of in vitro analytical parameters to generate an AdFMD vaccine product profile to replace the current lot release test for traditional, inactivated FMD vaccines that requires FMDV challenge in livestock. The possibility of an indirect FMD vaccine potency test based on a serological alternative was initially investigated for a lead vaccine candidate, Adt.A24. Results show that serum virus neutralization (SVN) based serology testing for Adt.A24 vaccine lot release is not feasible, at least not in the context of vaccine potency assessment at one week post-vaccination. Thus, an in vitro infectious titer assay (tissue culture infectious dose 50, TCID50) which measures FMD infectious (protein expression) titer was established. Pre-validation results show acceptable assay variability and linearity and these data support further studies to validate the TCID50 assay as a potential potency release test. In addition, a quantitative physiochemical assay (HPLC) and three immunochemical assays (Fluorescent Focus-Forming Unit (FFU); tissue culture expression dose 50 (TCED50); Western blot) were developed for potential use as in vitro assays to monitor AdFMD vaccine lot-to-lot consistency and other potential applications. These results demonstrate the feasibility of using a traditional modified-live vaccine virus infectivity assay in combination with a set of physiochemical and immunochemical tests to build a vaccine product profile that will ensure the each AdFMD vaccine lot released is similar to a reference vaccine of proven clinical safety and efficacy.