Instability of a two-dimensional extremal black hole

We consider the perturbation of tachyon about the extremal ground state of a two-dimensional (2D) electrically charged black hole. It is found that the presenting potential to on-coming tachyonic wave takes a double-humped barrier well. This allows an exponentially growing mode with respect to time. This extremal ground state is classically unstable. We conclude that the 2D extremal electrically charged black hole cannot be a candidate for the stable endpoint of the Hawking evaporation.Comment: 9 pages 2 figures, RevTeX, to be published in Phys. Rev D, to obtain gifures contact Author ([email protected]

Negative modes in the four-dimensional stringy wormholes

We study the Giddings-Strominger wormholes in string theories. We found negative modes among O(4)-symmetric fluctuations about the non-singular wormhole background. Hence the stringy wormhole contribution to the euclidean functional integral is purely imaginary. This means that the stringy wormhole is a bounce (not an instanton) and describes the nucleation and growth of wormholes in the Minkowski spacetime.Comment: 12 pages 2 figures, RevTe

Knowledge, attitudes, and perceptions associated with HPV vaccination among female Korean and Chinese university students

Abstract Background Human papillomavirus (HPV) vaccination is a form of primary prevention for cervical cancer. The HPV vaccination rate of female university students is not high in Korea and China. Therefore, the purpose of this study was to identify and compare the factors associated with intention to receive HPV vaccination between Korean and Chinese female university students. Methods The participants were 273 Korean and 317 Chinese female university students who had not been vaccinated for HPV, and data were collected using a self-reported questionnaire about attitudes toward HPV vaccination, HPV knowledge, perceptions of HPV infection, and intention to receive HPV vaccine. Results There were no significant differences between the Korean and Chinese female university students in HPV knowledge, attitudes, perceptions, and vaccination intention. The factors influencing the intention of HPV vaccination in Korean students were a positive attitude toward the HPV vaccine and a high HPV knowledge score. For Chinese students, sexual experience, awareness of genital warts, a positive attitude toward the HPV vaccine, a high HPV knowledge scores, a perception of the seriousness of HPV infection, and negative emotions regarding HPV infection were significant factors. Conclusions It is important to improve attitudes and knowledge about HPV and the HPV vaccine in order to enhance HPV vaccination both in Korea and China. Perceived seriousness and negative emotions regarding HPV infection should be used as a framework to develop subject-tailored interventions in China

Transdifferentiation-inducing HCCR-1 oncogene

<p>Abstract</p> <p>Background</p> <p>Cell transdifferentiation is characterized by loss of some phenotypes along with acquisition of new phenotypes in differentiated cells. The differentiated state of a given cell is not irreversible. It depends on the up- and downregulation exerted by specific molecules.</p> <p>Results</p> <p>We report here that <it>HCCR-1</it>, previously shown to play an oncogenic role in human cancers, induces epithelial-to-mesenchymal transition (EMT) and mesenchymal-to-epithelial transition (MET) in human and mouse, respectively. The stem cell factor receptor CD117/c-Kit was induced in this transdifferentiated (EMT) sarcoma tissues. This MET occurring in <it>HCCR-1 </it>transfected cells is reminiscent of the transdifferentiation process during nephrogenesis. Indeed, expression of <it>HCCR-1 </it>was observed during the embryonic development of the kidney. This suggests that <it>HCCR-1 </it>might be involved in the transdifferentiation process of cancer stem cell.</p> <p>Conclusions</p> <p>Therefore, we propose that <it>HCCR-1 </it>may be a regulatory factor that stimulates morphogenesis of epithelia or mesenchyme during neoplastic transformation.</p

Brane inflation in tachyonic and non-tachyonic type 0B string theories

We consider the motion of the brane universe moving in a background bulk space of tachyonic and non-tachyonic type 0B string theory. The effective densities are calculated for both cases and they show different power law behavior. Brane inflation for non-tachyonic type 0B background has the same power law behavior as that for type IIB background. The brane inflation under tachyonic background is less divergent than the one without tachyon. The role of tachyonic field in brane inflation scenario is different from that of the ordinary matter field.Comment: 13 pages, no figure, RevTe

30 inch Roll-Based Production of High-Quality Graphene Films for Flexible Transparent Electrodes

We report that 30-inch scale multiple roll-to-roll transfer and wet chemical doping considerably enhance the electrical properties of the graphene films grown on roll-type Cu substrates by chemical vapor deposition. The resulting graphene films shows a sheet resistance as low as ~30 Ohm/sq at ~90 % transparency which is superior to commercial transparent electrodes such as indium tin oxides (ITO). The monolayer of graphene shows sheet resistances as low as ~125 Ohm/sq with 97.4% optical transmittance and half-integer quantum Hall effect, indicating the high-quality of these graphene films. As a practical application, we also fabricated a touch screen panel device based on the graphene transparent electrodes, showing extraordinary mechanical and electrical performances

Electronic and Magnetic Properties of Electron-doped Superconductor, Sm_{1.85}Ce_{0.15}CuO_{4-delta}

Temperature-dependent magnetization (M(T)) and specific heat (C_p(T)) measurements were carried out on single crystal Sm_{1.85}Ce_{0.15}CuO_{4-delta} (T_c = 16.5 K). The magnetic anisotropy in the static susceptibility, chi {equiv} M/H, is apparent not only in its magnitude but also in its temperature dependence, with chi_{perp} for H{perp}c larger than chi_{parallel} for H{parallel}c. For both field orientations, chi does not follow the Curie-Weiss behavior due to the small energy gap of the J = 7/2 multiplet above the J = 5/2 ground-state multiplet. However, with increasing temperature, chi_{parallel}(T) exhibits a broad minimum near 100 K and then a slow increase while chi_{perp}(T) shows a monotonic decrease. A sharp peak in C_p(T) at 4.7 K manifests an antiferromagnetic ordering. The electronic contribution, gamma, to C_p(T) is estimated to be gamma = 103.2 (7) mJ/moleSmK^2. The entropy associated with the magnetic ordering is much smaller than Rln2, where R is the gas constant, which is usually expected for the doublet ground state of Sm^{+3}. The unusual magnetic and electronic properties evident in M(T) and C_p(T) are probably due to a strong anisotropic interaction between conduction electrons and localized electrons at Sm^{+3} sites.Comment: 5 pages, 5 encapsulated postscript figures, late

Tibiofemoral osteoarthritis affects quality of life and function in elderly Koreans, with women more adversely affected than men

<p>Abstract</p> <p>Background</p> <p>The prevalence of knee osteoarthritis(OA) in East Asia is as common for men and even higher for women than that reported in the Caucasian population. Since both population aging and economic growth have taken place at a much faster pace in Asian countries, such as South Korea, one would expect knee OA to become a major public health problem. However, few studies have examined the influence of knee OA on the quality of life (QoL) and physical function in Asia. The aim of this cross-sectional study is to investigate the influence of knee osteoarthritis (OA) on the quality of life (QoL), function and lower extremity physical performance and the gender difference in its influence in elderly community residents in Korea.</p> <p>Methods</p> <p>Participants were from the population-based Hallym Aging Study (HAS). The mean age of the 504 study subjects was 70.2 years and 274 (54%) were women. Demographic information was obtained by questionnaire, and radiographic evaluations consisted of weight-bearing semi-flexed knee radiographs. Self-reported QoL and function were assessed using Western Ontario and McMaster Universities Osteoarthritis (WOMAC) Index and Short Form 12-item (SF-12). Performance-based lower extremity function was assessed using the tests consisting of standing balance, usual walk and chair stands. The odds ratios(ORs) for belonging to the worst quartile of WOMAC and physical performance test were calculated by logistic regression analysis in radiographic knee OA compared to non-OA after adjustment of confounders. Scores for SF-12 items were analyzed using general linear models and means adjusted for age, BMI and OA severity were compared.</p> <p>Results</p> <p>Subjects with radiographic knee OA had significantly increased OR for belonging to the worst WOMAC quartile(for pain, 2.13,95% confidence interval[CI], 1.33-3.40, for stiffness, 2.94,95% CI,1.78-4.86, and for function, 2.97, 95% CI,1.83-4.81) and significantly worse SF-12 scores compared to non-OA after adjustment of age, BMI and sex. Women had worse WOMAC and SF-12 scores compared to men, regardless of the presence of radiographic knee OA after adjustment of age, BMI and OA severity. OA subjects had significantly worse performance score for usual walk and chair stands compared to non-OA subjects, but the ORs were no more significant after adjustment of sex.</p> <p>Conclusions</p> <p>Knee OA negatively affects the QoL and physical function in both genders, but women are more adversely affected than men.</p

Blushift of a tachyon in the charged 2D black hole

We study the propagation of string fields (metric $G_{\mu\nu}$, Mawxell gauge potential $A_{\mu}$, dilaton $\Phi$, and tachyon $T$) in a two-dimensional (2D) charged black hole. It is shown that the tachyon is a propagating field both inside and outside the black hole. This becomes infinitely blueshifted at the inner horizon. We confirm that the inner horizon is unstable, whereas the outer horizon is stable.Comment: 15 pages 3 figures, RevTeX, to be published Phys. Rev. D52 (15 November,1995), to obtain the figures contact Author ([email protected]