What drives corporate insurance demand?: Evidence from directors’ and officers’ liability insurance in Korea (working paper)

This is the final version of the working paper.This paper provides empirical evidence that increasing risk results in higher demand for hedging among firms. In a natural experiment exploring the Korean Government’s legislative change on shareholder class action, I show that firms increase their directors’ and officers’ liability insurance coverage in response to increased litigation risk despite increasing price of buying further coverage. I further test the heterogeneous effects in two dimensions of corporations: industry classification, and type of shareholder-management relation. The results confirm that firms in high litigation risk industries and those having high agency conflicts between shareholders and management increase their insurance coverage relatively more. Overall, the results demonstrate that corporations adjust their hedging demand in response to changing risk environment and that the adjustment depends on the level of risk exposure of individual firms

What drives corporate insurance demand?: Evidence from directors’ and officers’ liability insurance in Korea

This is the author accepted manuscript. The final version is available from Elsevier via the DOI in this recordThis paper provides empirical evidence that increasing risk results in higher demand for hedging among firms. Through a natural experiment exploring the Korean Government's legislative change on shareholder class action, I show that firms increase the liability insurance coverage for their directors and officers in response to increased litigation risk, despite the increase in costs associated with buying further coverage. I further test the heterogeneous effects in two dimensions of corporations: industry classification, and type of shareholder-management relationship. The results confirm that firms in high litigation risk industries and those with high agency conflicts between shareholders and management increase their insurance coverage relatively more. Overall, the results demonstrate that corporations adjust their hedging demand in response to changing risk environment and that the adjustment depends on the level of risk exposure of individual firms

Origin of New Broad Raman D and G Peaks in Annealed Graphene

Since graphene, a single sheet of graphite, has all of its carbon atoms on the surface, its property is very sensitive to materials contacting the surface. Herein, we report novel Raman peaks observed in annealed graphene and elucidate their chemical origins by Raman spectroscopy and atomic force microscopy (AFM). Graphene annealed in oxygen-free atmosphere revealed very broad additional Raman peaks overlapping the D, G and 2D peaks of graphene itself. Based on the topographic confirmation by AFM, the new Raman peaks were attributed to amorphous carbon formed on the surface of graphene by carbonization of environmental hydrocarbons. While the carbonaceous layers were formed for a wide range of annealing temperature and time, they could be effectively removed by prolonged annealing in vacuum. This study underlines that spectral features of graphene and presumably other 2-dimensional materials are highly vulnerable to interference by foreign materials of molecular thickness.open116167Nsciescopu

Postoperative irradiation after implant placement: A pilot study for prosthetic reconstruction

published_or_final_versio

A Paclitaxel-Eluting Stent for the Prevention of Coronary Restenosis

Background Intimal hyperplasia and resulting restenosis limit the efficacy of coronary stenting. We studied a coronary stent coated with the antiproliferative agent paclitaxel as a means of preventing restenosis. Methods We conducted a multicenter, randomized, controlled, triple-blind study to evaluate the ability of a paclitaxel-eluting stent to inhibit restenosis. At three centers, 177 patients with discrete coronary lesions (<15 mm in length, 2.25 to 3.5 mm in diameter) underwent implantation of paclitaxel-eluting stents (low dose, 1.3 µg per square millimeter, or high dose, 3.1 µg per square millimeter) or control stents. Antiplatelet therapies included aspirin with ticlopidine (120 patients), clopidogrel (18 patients), or cilostazol (37 patients). Clinical follow-up was performed at one month and four to six months, and angiographic follow-up at four to six months. Results Technical success was achieved in 99 percent of the patients (176 of 177). At follow-up, the high-dose group, as compared with the control group, had significantly better results for the degree of stenosis (mean [±SD], 14±21 percent vs. 39±27 percent; P<0.001), late loss of luminal diameter (0.29±0.72 mm vs. 1.04±0.83 mm, P<0.001), and restenosis of more than 50 percent (4 percent vs. 27 percent, P<0.001). Intravascular ultrasound analysis demonstrated a dose-dependent reduction in the volume of intimal hyperplasia (31, 18, and 13 mm3, in the high-dose, low-dose, and control groups, respectively). There was a higher rate of major cardiac events in patients receiving cilostazol than in those receiving ticlopidine or clopidogrel. Among patients receiving ticlopidine or clopidogrel, event-free survival was 98 percent and 100 percent in the high-dose and control groups, respectively, at one month, and 96 percent in both at four to six months. Conclusions Paclitaxel-eluting stents used with conventional antiplatelet therapy effectively inhibit restenosis and neointimal hyperplasia, with a safety profile similar to that of standard stents.published_or_final_versio

Nanosheet thickness-modulated MoS2 dielectric property evidenced by field-effect transistor performance

We report on the nanosheet-thickness effects on the performance of top-gate MoS2 field-effect transistors (FETs), which is directly related to the MoS2 dielectric constant. Our top-gate nanosheet FETs with 40 nm thin Al2O3 displayed at least an order of magnitude higher mobility than those of bottom-gate nanosheet FETs with 285 nm thick SiO2, benefiting from the dielectric screening by high-k Al2O3. Among the top-gate devices, the single-layered FET demonstrated the highest mobility of similar to 170 cm(2) V-1 s(-1) with 90 mV dec(-1) as the smallest subthreshold swing (SS) but the double-and triple-layered FETs showed only similar to 25 and similar to 15 cm(2) V-1 s(-1) respectively with the large SS of 0.5 and 1.1 V dec(-1). Such property degradation with MoS2 thickness is attributed to its dielectric constant increase, which could rather reduce the benefits from the top-gate high-k dielectric.open115353Nsciescopu

A Retrospective Study Comparing Crossed and Lateral Wire Configurations in Paediatric Supracondylar Fractures

BACKGROUND: Supracondylar fractures are common in children and are associated with significant morbidity. The purpose of our study was to assess and compare the clinical and radiological outcome of management of supracondylar fractures by both wire configurations, along with identifying factors that predispose to complications. MATERIALS & METHODS: We retrospectively reviewed all paediatric cases admitted with a supracondylar fracture over a five year period. We reviewed case notes, theatre records and radiographs to determine the age of the patient, classification of fracture, treatment method, delay to theatre, duration of surgery, wire configuration, Baumann´s angle, radiocapitellar alignment, anterior humeral alignment and complications. RESULTS: During the five year period we admitted 132 patients and complete notes were available for 123 patients for analyses. For all the patients managed with wire stabilisation 23% developed complications, including 13% with significant complications including nerve injuries and fracture displacements. All five nerve injuries had crossed wires, whereas all for fracture displacements had lateral wires. Baumann´s angle was 76.7 degrees in the group with no complication and 72.2 degrees in the significant complication group (p=0.02). Radiocapitellar line and anterior humeral line were not satisfactory in 5% and 15% of the group with no complications, and 17% and 33% of the group with significant complications. CONCLUSION: We found more complications in lateral pinning configurations, although all nerve injuries were in patients with crossed wire configurations. The factors we believe are associated with a higher likelihood of complications are inadequate post-operative radiological appearance

A sense of embodiment is reflected in people's signature size

BACKGROUND: The size of a person's signature may reveal implicit information about how the self is perceived although this has not been closely examined. METHODS/RESULTS: We conducted three experiments to test whether increases in signature size can be induced. Specifically, the aim of these experiments was to test whether changes in signature size reflect a person's current implicit sense of embodiment. Experiment 1 showed that an implicit affect task (positive subliminal evaluative conditioning) led to increases in signature size relative to an affectively neutral task, showing that implicit affective cues alter signature size. Experiments 2 and 3 demonstrated increases in signature size following experiential self-focus on sensory and affective stimuli relative to both conceptual self-focus and external (non-self-focus) in both healthy participants and patients with anorexia nervosa, a disorder associated with self-evaluation and a sense of disembodiment. In all three experiments, increases in signature size were unrelated to changes in self-reported mood and larger than manipulation unrelated variations. CONCLUSIONS: Together, these findings suggest that a person's sense of embodiment is reflected in their signature size

Comparison of the tetrahedron method to smearing methods for the electronic density of states

The electronic density of states (DOS) highlights fundamental properties of materials that oftentimes dictate their properties, such as the band gap and Van Hove singularities. In this short note, we discuss how sharp features of the density of states can be obscured by smearing methods (such as the Gaussian and Fermi smearing methods) when calculating the DOS. While the common approach to reach a "converged" density of states of a material is to increase the discrete k-point mesh density, we show that the DOS calculated by smearing methods can appear to converge but not to the correct DOS. Employing the tetrahedron method for Brillouin zone integration resolves key features of the density of states far better than smearing methods

Duality between N=5 and N=6 Chern-Simons matter theory

We provide evidences for the duality between ${\cal N}=6$ $U(M)_{4} \times U(N)_{-4}$ Chern-Simons matter theory and ${\cal N}=5$ $O(\hat{M})_{2} \times USp(2\hat{N})_{-1}$ theory for a suitable $\hat{M},\hat{N}$ by working out the superconformal index, which shows perfect matching. For ${\cal N}=5$ theories, we show that supersymmetry is enhanced to ${\cal N}=6$ by explicitly constructing monopole operators filling in $SO(6)_R$ $R$-currents. Finally we work out the large $N$ index of $O(2N)_{2k} \times USp(2N)_{-k}$ and show that it exactly matches with the gravity index on $AdS_4 \times S^7/D_k$, which further provides additional evidence for the duality between the ${\cal N}=5$ and ${\cal N}=6$ theory for $k=1$Comment: 15 pages; references adde