Shaping single crystalline BaTiO3nanostructures by focused neon or helium ion milling.

The realization of perovskite oxide nanostructures with controlled shape and dimensions remains a challenge. Here, we investigate the use of helium and neon focused ion beam (FIB) milling in an ion microscope to fabricate BaTiO3nanopillars of sub-500 nm in diameter starting from BaTiO3(001) single crystals. Irradiation of BaTiO3with He ions induces the formation of nanobubbles inside the material, eventually leading to surface swelling and blistering. Ne-FIB is shown to be suitable for milling without inducing surface swelling. The resulting structures are defect-free single crystal nanopillars, which are enveloped, on the top and lateral sidewalls, by a point defect-rich crystalline region and an outer Ne-rich amorphous layer. The amorphous layer can be selectively etched by dipping in diluted HF. The geometry and beam-induced damage of the milled nanopillars depend strongly on the patterning parameters and can be well controlled. Ne ion milling is shown to be an effective method to rapidly prototype BaTiO3crystalline nanostructures.

Temporal change in the diagnosis and treatment rates of osteoporosis: results from the Korea National Health and Nutrition Examination Survey.

To compare the diagnosis andtreatment rates of osteoporosis and diabetes in Korea, a nationwide database was used. The results showed that although osteoporosis management is improving, it is still lower compared with that of diabetes; thus, further efforts are needed in this regard. INTRODUCTION: This study aimed to re-evaluate the diagnosis and treatment of osteoporosis from the KNHANES 2016-2017 and compare the temporal change of the rate with those of diabetes as another prevalent chronic disease in South Korea. METHODS: The prevalence of osteoporosis in 2016 was estimated using the previous data classified by age groups (50-59,60-69, and ≥70years) and the 2016 Korean census data. The physician diagnosis and treatment rates of osteoporosis in adults aged ≥50years were estimated using the 2016-2017 KNHANES data. The physician diagnosis and treatment rates of diabetes were evaluated using the KNHANES 2008-2009 and 2016-2017 data. RESULTS: The estimated physician diagnosisrate of osteoporosis increased from 29.9% in females and 5.8% in males in 2008-2009 to 62.8% in females and 22.8% in males in 2016-2017. The treatment rate for the estimated total number of patients with osteoporosis increased from 14.4% in females and 3.8% in males in 2008-2009 to 32.2% in females and 9.0% in males in 2016-2017. An increasing trend in the estimated treatment rateof physician-diagnosed osteoporosis patients was not observed (48.3% [2008-2009] vs 51.5% [2016-2017] in females; 42.6% [2008-2009] vs 42.2% [2016-2017] in males). The physician diagnosis and treatment rates of diabetes were considerably better and more stable than those of osteoporosis. CONCLUSION: Osteoporosis management in South Korea is improving but is insufficient compared with diabetes management. More extensive efforts are needed to improve the diagnosis and treatment rates of osteoporosis.

Hyperattenuating lesions after mechanical thrombectomy in acute ischaemic stroke: factors predicting symptomatic haemorrhage and clinical outcomes.

AIM: To evaluate the clinical significance of hyperattenuating lesions on CT after mechanical thrombectomy for acute ischaemic stroke, and to identify imaging factors that predict symptomatic haemorrhage and unfavourable outcomes. MATERIALS AND METHODS: Seventy-eight patients with acute ischaemic stroke in the anterior circulation who underwent mechanical thrombectomy were evaluated. All patients underwent post-interventional unenhanced computed tomography (CT) within 24 h and follow-up CT or magnetic resonance imaging (MRI) within 7 days. Baseline characteristics and clinical outcomes were compared between patients with and without hyperattenuating lesions. In patients with hyperattenuating lesions, clinical and imaging factors that predict symptomatic haemorrhage and unfavourable outcomes were determined. RESULTS: Fifty-six of 78 patients (71.8%) demonstrated hyperattenuating lesions on post-interventional CT. Patients with hyperattenuating lesions showed lower Alberta Stroke Program Early CT score (ASPECTS), persistent/symptomatic haemorrhage, and unfavourable outcomes than those without. In patients with hyperattenuating lesions, larger hyperattenuating lesion volume (>21.3 ml; OR, 55.60, p<0.001) and perilesional oedema (OR, 46.04, p=0.015) were independent factors predicting symptomatic haemorrhage. Older age (OR, 1.2, p=0.006) and lower ASPECTS (OR, 0.45, p=0.046) were independent factors predicting unfavourable outcomes in patients with hyperattenuating lesions. Adding the volume of the hyperattenuating lesion to age and ASPECTS increased the predictive performance of unfavourable outcomes (area under the curve 0.874 versus 0.934, p=0.043). CONCLUSIONS: Hyperattenuating lesions on post-interventional CT are associated with increased risk of symptomatic haemorrhage and unfavourable outcomes. Larger hyperattenuating lesion volume is an independent factor of symptomatic haemorrhage and it has added predictive value for unfavourable outcomes.

Lower Breakpoint of Intracranial Amplitude-Pressure Relationship in Normal Pressure Hydrocephalus.

The relationship between intracranial pulse amplitude (AMP) and mean intracranial pressure (ICP) has been previously described. Generally, AMP increases proportionally to rises in ICP. However, at low ICP a lower breakpoint (LB) of amplitude-pressure relationship can be observed, below which pulse amplitude stays constant when ICP varies. Theoretically, below this breakpoint, the pressure-volume relationship is linear (good compensatory reserve, brain compliance stays constant); above the breakpoint, it is exponential (brain compliance decreases with rising ICP).Infusion tests performed in 169 patients diagnosed for idiopathic normal pressure hydrocephalus (iNPH) during the period 2004-2013 were available for analysis. A lower breakpoint was observed in 62 patients diagnosed for iNPH. Improvement after shunt surgery in patients in whom LB was recorded was 77% versus 90% in patients where LB was absent (p < 0.02). There was no correlation between improvement and slope of amplitude-pressure line above LB.The detection of a lower breakpoint is associated with less frequent improvement after shunting in NPH. It may be interpreted that cerebrospinal fluid dynamics of patients working on the flat part of the pressure-volume curve and having a 'luxurious' compensatory reserve, are more frequently caused by brain atrophy, which is obviously not responding to shunting.

Migrant status and identification as ultra-high risk for psychosis and transitioning to a psychotic disorder.

BACKGROUND: Certain migrant groups are more likely to develop a psychotic disorder compared to the native-born populations, and a younger age at migration is associated with greater risk. However, it is not known at which stage migration has an effect on the development of psychotic disorders. We examined whether migrants were more likely to be identified as ultra-high risk for psychosis (UHR) compared to native-born young people and whether migrant status was associated with the risk of transition to a full-threshold psychotic disorder. METHODS: The cohort included all young people aged 15-24 who were identified as UHR at a specialist clinic over a five-year period (2012-16). Australian census data were used to obtain the at-risk population. Poisson regression was used to calculate rate ratios and Cox regression analysis determined hazard ratios. RESULTS: 467 young people were identified as UHR, of which 13.5% (n = 63) were born overseas. First-generation migrants were 2.6-fold less likely to be identified as UHR compared to Australian-born young people (IRR = 0.39, 95% CI [0.30, 0.51], P < 0.001). There was no difference between migrant and native-born young people in their risk of transitioning to a psychotic disorder (HR = 0.90, 95% CI [0.39, 2.08], P = 0.81). CONCLUSIONS: UHR first-generation migrants may be under-accessing mental health services.

Lack of association between early menopause and non-alcoholic fatty liver disease in postmenopausal women.

Background: The possibility of an association between early menopause and the risk of non-alcoholic fatty liver disease (NAFLD) is as yet unclear.Methods: The subjects consisted of 4354 postmenopausal women who participated in the 2010-2012 Korea National Health and Nutrition Examination Survey. Early, normal, and late menopause were defined as age at menopause <45 years, 45-54 years, and ≥55 years, respectively. NAFLD was defined by a hepatic steatosis index of >36.Results: When compared with normal menopausal women, early or late menopausal women had no significant differences in the odds ratios (ORs) of NAFLD: OR = 1.05, 95% confidence interval (CI), 0.83-1.32 and OR = 1.02, 95% CI, 0.75-1.39, respectively. These results remained similar after adjustment for known risk factors for NAFLD, reproductive factors, and comorbidities. The OR for NAFLD per 1-year increase in age at menopause was 1.01 (95% CI, 0.99-1.03; p = 0.329). The prevalence of advanced fibrosis was 2.1% (95% CI, 0.7-6.4%), 2.2% (95% CI, 1.3-3.8%), and 3.9% (95% CI, 1.2-12.2%) in early, normal, and late menopausal women, respectively.Conclusions: This study provides no evidence for an association of early menopause with NAFLD risk. However, NAFLD-related advanced fibrosis is highly prevalent in postmenopausal women.

Circulating calcium levels and the risk of type 2 diabetes: a systematic review and meta-analysis.

Abnormal Ca homeostasis has been associated with impaired glucose metabolism. However, the epidemiological evidence is controversial. We aimed to assess the association between circulating Ca levels and the risk of type 2 diabetes mellitus (T2DM) or abnormal glucose homeostasis through conducting a systematic review and meta-analysis. Eligible studies were identified by searching electronic database (PubMed, Embase and Google Scholar) and related references with de novo results from primary studies up to December 2018. A random-effects meta-analysis was performed to estimate the weighted relative risks (RR) and 95 % CI for the associations. The search yielded twenty eligible publications with eight cohort studies identified for the meta-analysis, which included a total of 89 165 participants. Comparing the highest with the lowest category of albumin-adjusted serum Ca, the pooled RR was 1·14 (95 % CI 1·05, 1·24) for T2DM (n 51 489). Similarly, serum total Ca was associated with incident T2DM (RR 1·25; 95 % CI 1·10, 1·42) (n 64 502). Additionally, the adjusted RR for 1 mg/dl increments in albumin-adjusted serum Ca or serum total Ca levels was 1·16 (95 % CI 1·07, 1·27) and 1·19 (95 % CI 1·11, 1·28), respectively. The observed associations remained with the inclusion of a cohort study with ionised Ca as the exposure. However, data pooled from neither case-control (n 4) nor cross-sectional (n 8) studies manifested a significant correlation between circulating Ca and glucose homeostasis. In conclusion, accumulated data from the cohort studies suggest that higher circulating Ca levels are associated with an augmented risk of T2DM.

4f Crystal Field Ground State of the Strongly Correlated Topological Insulator SmB_{6}.

We investigated the crystal-electric field ground state of the 4f manifold in the strongly correlated topological insulator SmB_{6} using core-level nonresonant inelastic x-ray scattering. The directional dependence of the scattering function that arises from higher multipole transitions establishes unambiguously that the Γ_{8} quartet state of the Sm f^{5} J=5/2 configuration governs the ground-state symmetry and, hence, the topological properties of SmB_{6}. Our findings contradict the results of density functional calculations reported so far.

Combined effects of diabetes and low household income on mortality: a 12-year follow-up study of 505 677 Korean adults.

AIM: To examine the effects of diabetes, low income and their combination on mortality in the Korean population. METHODS: We analysed a total of 505 677 people (53.9% male) aged 40-79 years old from the National Health Insurance Service-National Health Screening (NHIS-HEALS) cohort. Ten levels of household income were used as indicators of economic status. Diabetes was defined as elevated fasting blood glucose (≥ 6.9 mmol/l) and/or use of glucose-lowering drugs or insulin. Covariates of age, sex, BMI, smoking and Charlson Comorbidity Index were determined at baseline. Outcomes were total and cause-specific mortality over 12 years. Cox's proportional hazard regression models were used to estimate hazard ratios (HRs) for mortality according to the presence of diabetes, household income and their combination. RESULTS: Lower household income was associated with higher mortality from all causes, cardiovascular disease, cancer and non-cancer non-cardiovascular causes. Excessive mortality due to low incomes was observed in both people with and without diabetes. In men, the adjusted HR [95% confidence interval (CI)] of mortality was 1.38 (1.34 to 1.42) for low-income only, 1.48 (1.42 to 1.55) for diabetes only and 1.95 (1.86 to 2.05) for diabetes and low-income combined, relative to the normal glucose and high income group. Corresponding HR (95% CI) in women were 1.19 (1.14 to 1.24), 1.54 (1.44 to 1.64) and 1.87 (1.75 to 2.01), respectively. CONCLUSION: Both low household income and the presence of diabetes independently increase the risk of mortality, but their combined effects on mortality may be different between men and women.

Co-clinical trials demonstrate predictive biomarkers for dovitinib, an FGFR inhibitor, in lung squamous cell carcinoma.

BACKGROUND: We conducted co-clinical trials in patient-derived xenograft (PDX) models to identify predictive biomarkers for the multikinase inhibitor dovitinib in lung squamous cell carcinoma (LSCC). METHODS: The PDX01-02 were established from LSCC patients enrolled in the phase II trial of dovitinib (NCT01861197) and PDX03-05 were established from LSCC patients receiving surgery. These five PDX tumors were subjected to in vivo test of dovitinib efficacy, whole exome sequencing and gene expression profiling. RESULTS: The PDX tumors recapitulate histopathological properties and maintain genomic characteristics of originating tumors. Concordant with clinical outcomes of the trial enrolled-LSCC patients, dovitinib produced substantial tumor regression in PDX-01 and PDX-05, whereas it resulted in tumor progression in PDX-02. PDX-03 and -04 also displayed poor antitumor efficacy to dovitinib. Mutational and genome-wide copy number profiles revealed no correlation between genomic alterations of FGFR1-3 and sensitivity to dovitinib. Of note, gene expression profiles revealed differentially expressed genes including FGF3 and FGF19 between PDX-01 and 05 and PDX-02-04. Pathway analysis identified two FGFR signaling-related gene sets, FGFR ligand binding/activation and SHC-mediated cascade pathway were substantially up-regulated in PDX-01 and 05, compared with PDX-02-04. The comparison of gene expression profiles between dovitinib-sensitive versus -resistant lung cancer cell lines in the Cancer Cell Line Encyclopedia database also found that transcriptional activation of 18 key signaling components in FGFR pathways can predict the sensitivity to dovitinib both in cell lines and PDX tumors. These results highlight FGFR pathway activation as a key molecular determinant for sensitivity to dovitinib. CONCLUSIONS: FGFR gene expression signatures are predictors for the response to dovitinib in LSCC.

Influence of a ring-shaped pump beam on temperature distribution and thermal lensing in end-pumped solid state lasers.

A simple method for reducing thermal lensing in an end-pumped solid state laser using a ring-shaped pump beam is reported. Analytical expressions for the temperature distribution and the thermal lensing focal length in a laser medium end-pumped by a beam with a ring-shaped intensity profile are derived. The results indicate that thermal effects including thermal lensing can be significantly reduced due to a more uniform temperature distribution. This approach has been applied to a Nd:YVO4 amplifier operating at 1064 nm confirming that the brightness of the output beam can be remarkably improved at high power levels due to the better beam quality for the ring-shaped pumping compared to the conventional quasi-top-hat pumping. The prospects for power scaling and further improvement in laser performance will be discussed.

Cardiovascular events associated with second-line anti-diabetes treatments: analysis of real-world Korean data.

AIM: To compare the risks of cardiovascular disease (CVD) and all-cause mortality associated with sulfonylurea (SU), dipeptidyl peptidase-4 inhibitor (DPP4i) and thiazolidinedione (TZD) as add-on medications to metformin (MET) therapy in people with Type 2 diabetes. METHODS: We identified 40 263 individuals who used SU (n = 11 582), DPP4i (n = 26 623) or TZD (n = 2058) in addition to MET between January 2013 and June 2015 from the database of the Korean National Health Insurance, the single-payer healthcare system in South Korea. Cox proportional hazard models were used to estimate hazard ratios for major CVD event (coronary artery disease, heart failure, stroke or transient ischaemic attack) development and all-cause mortality by second-line anti-diabetes medication type. Age, sex, duration of MET monotherapy, calendar year and comorbid conditions were adjusted as potential confounders. RESULTS: The observed numbers of CVD events (total observed person-time) were 485 (18 778 person-years) for MET + SU, 744 (40 374 person-years) for MET + DPP4i and 60 (3014 person-years) for MET + TZD users. Compared with MET + SU users, the fully adjusted hazard ratios for CVD events were 0.79 [95% confidence interval (CI): 0.71-0.89] for MET + DPP4i users and 0.85 (95% CI: 0.65-1.11) for MET + TZD users. The corresponding hazard ratios for all-cause mortality were 0.84 (95% CI: 0.66-1.07) for MET + DPP4i users and 0.67 (95% CI: 0.35-1.28) for MET + TZD users. CONCLUSION: Analysis of Korea National Health Insurance database showed that MET + DPP4i treatment for diabetes had a lower CVD risk than MET + SU treatment.

Clinical implication of novel drug resistance-conferring mutations in resistant tuberculosis.

Evolving novel and/or unfamiliar mutations are revolutionizing the pathways of antibiotic resistance of clinical tuberculosis. The accumulation and interaction of these poorly characterized mutations augment the complexity of resistant pathogenic strains and raise public health concerns. This article reviews our current understanding of the genetic changes that characterize drug resistance in tuberculosis and highlights the imperative for further investigations focusing on the effects of an individual mutation and interacting mutations with detailed strain epidemiology, particularly as these pertain to technology-limited countries with high tuberculosis incidence rates. Concomitantly, there is a need for the development, testing, and uptake of new tools for studying the effects of these mutations in drug resistance and fitness cost of the pathogen. Such genetic data are critical for effective localized and global tuberculosis control interventions and for accurate epidemiological predictions.

Learning curve for robotic esophagectomy and dissection of bilateral recurrent laryngeal nerve nodes for esophageal cancer.

Dissection of bilateral recurrent laryngeal nerve (RLN) nodes is a technically demanding procedure, but robotic systems have been useful for RLN node dissection. This retrospective study investigated the learning curve for bilateral RLN node dissection in esophageal-cancer patients using a robotic system for esophageal cancer. We retrospectively reviewed 33 consecutive patients who received a robotic esophagectomy and total lymphadenectomy by single surgeon. The patients were divided into either group 1 (initial 20 cases) or group 2 (later 13 cases). The mean patient age was 61.88 ± 9.03 years and 28 (84.8%) patients were male. Most cases were pathologically diagnosed as squamous cell carcinoma. The lesion locations included 3 (9.1%) in the upper esophagus, 12 (63.6%) in the mid esophagus, and 9 (27.3%) in the lower esophagus. Eleven (33.3%) cases were stage I, 7 (21.2%) were stage II, and 15 (45.5%) were stage III. One case in group 2 (3%) suffered operative mortality. Operation time, robot console time, and blood loss were similar between the two groups. The timing of right and left RLN node dissection, the number of total dissected lymph nodes, and the percentage of dissected right and left RLN nodes were also comparable. However, the incidence of vocal cord palsy was significantly lower in group 2 (55% vs. 0%, p= 0.02). The incidence of other operative complications did not vary between the two groups. Even though operative outcomes and incidence of other complications were comparable between the two groups, the incidence of vocal cord palsy decreased significantly after 20 cases. Thus, we conclude that a minimum of 20 cases is required before a surgeon is experienced enough to perform safe dissection of bilateral RLN nodes.

Adaptable beam profiles from a dual-cavity Nd:YAG laser.

We report a technique to tailor a laser beam profile from a donut to quasi-top-hat intensity distribution, directly from the laser, simply achieved by simultaneous excitation and control of the relative contributions of the fundamental (TEM00) and first-order Laguerre-Gaussian (LG01) transverse modes. Exploiting a dual-cavity configuration with a single Nd:YAG gain element, adaptable continuous-wave laser beam profiles from the primary cavity could be obtained by varying the diffraction loss of an acousto-optic modulator in the secondary cavity. We investigate the resultant beam profiles as a function of pump power and the AOM diffraction loss, and discuss the prospects for tunable laser beams profiles.

Domain wall conductivity in semiconducting hexagonal ferroelectric TbMnO3 thin films.

Although enhanced conductivity of ferroelectric domain boundaries has been found in BiFeO3 and Pb(Zr,Ti)O3 films as well as hexagonal rare-earth manganite single crystals, the mechanism of the domain wall conductivity is still under debate. Using conductive atomic force microscopy, we observe enhanced conductance at the electrically-neutral domain walls in semiconducting hexagonal ferroelectric TbMnO3 thin films where the structure and polarization direction are strongly constrained along the c-axis. This result indicates that domain wall conductivity in ferroelectric rare-earth manganites is not limited to charged domain walls. We show that the observed conductivity in the TbMnO3 films is governed by a single conduction mechanism, namely, the back-to-back Schottky diodes tuned by the segregation of defects.

Multidetector CT angiography in the diagnosis and classification of carotid-cavernous fistula.

AIM: To evaluate the performance of multidetector computed tomography angiography (MDCTA) in identifying and classifying carotid-cavernous fistulas (CCFs). MATERIALS AND METHODS: The neuro-interventional database was searched for patients with CCFs at four different institutions and for normal controls at one of the four institutions. Thirty-four patients were divided into the case group (direct type, n=8; indirect type, n=8) and the control group (n=18). Two readers retrospectively evaluated thin-section CTA images for the presence and laterality of four findings: (1) engorged ophthalmic vein, (2) engorged cavernous sinus, (3) similar enhancement of the cavernous sinus (CS) and internal carotid artery (ICA), and (4) greater enhancement of the CS than the transverse sinus (TS). Dehiscent ICA for the direct type was assessed only in the case group. Sensitivity, specificity, and inter-reader agreement were determined. Attenuation differences between the ICA and CS and between the CS and TS were compared across groups. RESULTS: The sensitivity/specificity for two engorgement and two enhancement findings were 81%/100%, 88%/94%, 100%/100%, and 88%/100%, respectively, for Reader 1, and 75%/100%, 75%/100%, 88%/100%, and 88%/100%, respectively, for Reader 2. Agreement between readers was excellent for all findings (κ>0.80). Dehiscent ICA identified the direct type with a sensitivity/specificity of 100%/75% for Reader 1 and 100%/88% for Reader 2 (κ=0.871). In the case group, the difference between ICA and CS attenuation values was significantly lower (180.1±76.6 versus 7.5±23.7; ⤳<0.001) and that between CS and TS were higher (-31.2±69 versus 102.6±59.3; ⤳<0.001). The area under the curve for the latter values was 0.95. CONCLUSION: The engorgement and enhancement categories in MDCTA may perform comparably in identifying CCFs and measurements of vessel attenuation differences may be of high diagnostic value. Dehiscent ICA can greatly aid in identifying the direct type.

Robot-assisted thoracoscopic esophagectomy with extensive mediastinal lymphadenectomy: experience with 114 consecutive patients with intrathoracic esophageal cancer.

The study aims to report the operative outcomes of robot-assisted thoracoscopic esophagectomy (RATE) with extensive mediastinal lymphadenectomy (ML) for intrathoracic esophageal cancer. We analyzed a prospective database of 114 consecutive patients who underwent RATE with lymph node dissection along recurrent laryngeal nerve (RLN) followed by cervical esophagogastrostomy. The study included 104 men with a mean age of 63.1 ± 0.8 years. Of these, 110 (96.5%) had squamous cell carcinoma, and the location of the tumor was upper esophagus in 7 (6.1%), middle in 62 (54.4%), and lower in 45 (39.5%). Preoperative concurrent chemoradiation was performed in 15 patients (13.2%). All but one patient underwent successful RATE, and R0 resection was achieved in 111 patients (97.4%). Extended ML and total ML were performed in 24 (21.1%) and 90 (78.9%) patients, respectively. Total operation time was 419.6 ± 7.9 minutes, and robot console time was 206.6 ± 5.2 minutes. The mean number of total, mediastinal, and RLN nodes was 43.5 ± 1.4, 24.5 ± 1.0, and 9.7 ± 0.7, respectively. The most common complication was RLN palsy (30, 26.3%), followed by anastomotic leakage (17, 14.9%) and pulmonary complications (11, 9.6%). Median hospital stay was 16 days, and 90-day mortality was observed in three patients (2.5%). On multivariate analysis, preoperative concurrent chemoradiation was a risk factor for pulmonary complications (odds ratio 7.42, 95% confidence interval 1.91-28.8, P = 0.004). RATE with extensive ML could be performed safely with acceptable postoperative outcomes. Long-term survival data should be followed in the future to verify the oncological outcome of the procedure.

Topological surface state in the Kondo insulator samarium hexaboride.

Topological invariants of electron wavefunctions in condensed matter reveal many intriguing phenomena. A notable example is provided by topological insulators, which are characterized by an insulating bulk coexisting with a metallic boundary state. Although there has been intense interest in Bi-based topological insulators, their behaviour is complicated by the presence of a considerable residual bulk conductivity. Theories predict that the Kondo insulator system SmB6, which is known to undergo a transition from a Kondo lattice metal to a small-gap insulator state with decreasing temperature, could be a topological insulator. Although the insulating bulk and metallic surface separation has been demonstrated in recent transport measurements, these have not demonstrated the topologically protected nature of the metallic surface state. Here we report thickness-dependent transport measurements on doped SmB6, and show that magnetic and non-magnetic doping results in contrasting behaviour that supports the conclusion that SmB6 shows virtually no residual bulk conductivity.

Direct generation of an optical vortex beam in a single-frequency Nd:YVO4 laser.

A simple method for generating a Laguerre-Gaussian (LG) mode optical vortex beam with well-determined handedness in a single-frequency solid state laser end-pumped by a ring-shaped pump beam is reported. After investigating the intensity profile and the wavefront helicity of each longitudinal mode output to understand generation of the LG mode in a Nd:YVO4 laser resonator, selection of the wavefront handedness has been achieved simply by inserting and tilting an etalon in the resonator, which breaks the propagation symmetry of the Poynting vectors with opposite helicity. Simple calculation and the experimental results are discussed for supporting this selection mechanism.