Umbral Calculus and the Frobenius-Euler Polynomials

We study some properties of umbral calculus related to the Appell sequence. From those properties, we derive new and interesting identities of the Frobenius-Euler polynomials

Large scale physical model testing on the ultimate strength of a steel stiffened plate structure under cyclic compressive loading

See the pdf fil

Large scale physical model testing on the ultimate compressive strength of a steel stiffened plate structure at cryogenic condition

Ship structures are typical examples of large plated structures which are made of large number of structural elements composed into system structures to be strong enough, while keeping the structural weight at minimum, to survive varying loads arising from cargo (e.g. weight and cryogenic condition due to LNG cargo), waves, winds or other environmental conditions (e.g. cold temperature due to Arctic operation). The design of ship structures are today designed based on limit states which are defined by the description of a condition for which a particular structural member or an entire structure would fail to perform the function designated beforehand. Four types of limit states are relevant, namely SLS (serviceability limit state), ULS (ultimate limit state), FLS (fatigue limit state) and ALS (accidental limit state). At the preliminary design stage, structural scantlings and materials of ship structures are determined based on the ULS, and ultimately other types of limit states are integrated to ensure so that the different parts of a ship structure will meet safety requirements and survive environmental and operational conditions during the life time period of some 25 years. \ua0The stiffened plate structures in the bottom, the deck and the side-shell are the most important parts of a ship in association with a ship’s integrity, safety and survivability. The design criteria for determining the scantlings of stiffened plate structures are the ultimate limit states (or ultimate strength). If applied loads exceed the ultimate strength then the stiffened plate structures fail to perform the function, leading to total loss of the ship. Therefore, it is of vital importance to accurately and efficiently compute the ultimate strength of stiffened plate structures. The behavior of stiffened plate structures until and after the ultimate strength is reached is highly nonlinear involving geometric nonlinearities (e.g. buckling and large deflection) and material nonlinearities (e.g. yielding, plasticity and material failure or fracture). Various types of collapse modes, including overall buckling collapse, beam-column type collapse, web buckling induced collapse and flexural-torsional buckling induced collapse, are relevant. Today\u27s large merchant ship structures are made of different grades of steel materials that should meet specific requirements for yield strength, ductility, brittleness, ultimate tensile strength resistance to corrosion in association with operational and environmental conditions.\ua0\ua0As of today, the ultimate strength of stiffened plate structures has been studied and applied in room temperature conditions. However, ships now operate in Arctic region at cold temperatures as climate change causes Arctic ice to melt at an alarming rate. A shipping company MAERSK recently navigates a 200m long container ship through the Arctic waters for the first time without the help of icebreakers. The average ambient temperature in Arctic region during winter season is -40 deg. C and the lowest temperature is reportedly -68 deg. C. Furthermore, the number of LNG-fueled ships is increasing in terms of resolving the issues associated with CO2 emissions. LNG-fueled ships need to have LNG fuel tanks in a large size, and hazards of LNG leakage always exist. The temperature of LNG is -163 deg. C. The collapse behavior of ship stiffened plate structures is vulnerable to cold temperatures or cryogenic condition in association with catastrophic failure, leading to total loss of ships that can affect personnel, assets and the environment, where brittle facture must be playing a significant role on the ultimate strength behavior. Theoretical methods are almost impossible to apply for computing such a highly nonlinear behavior of ship stiffened plate structures involving buckling, yielding and brittle fracture. Advanced computational models should be developed for that purpose. However, it is highly demanding to obtain physical model test database which shall be used to validate the accuracy and applicability of the advanced computational models.\ua0The purpose of the present study is to obtain physical model test database on the ultimate strength characteristics of ship stiffened plate structures subject to extreme loads and cold temperatures (due to LNG leakage). Physical model testing on a large scale ship stiffened plate structure is undertaken at cryogenic condition (-160 deg. C). Elastic-plastic large deflection behavior of the test model under axial compressive loads is measured until and after the ultimate strength is reached. Material properties at cryogenic temperature are tested in separate material experiments. Details of the test database are documented

Treatment-Seeking Behaviors and Related Epidemiological Features in Korean Acne Patients

Little is known about the treatment-seeking behaviors of acne patients, especially Asian acne patients. This study was performed to obtain detailed information about the treatment-seeking behaviors in Korean acne patients. Patients who visited the dermatology departments at 17 university hospitals completed a self-administered questionnaire. Most patients obtained information about acne from doctors or the Internet. The most important criteria for selecting a treatment method or choosing a particular clinic were effectiveness and accessibility. Patients used traditional medicine, visited beauty clinics, drank more water, and used over-the-counter topical agents more frequently than they sought doctors during the worsening period. The degree of satisfaction in treatment was found to depend on the total cost of treatment, number of places visited, site affected by acne, and emotional stress. Those who had experienced a side effect tended to have been treated for longer, to have paid more for treatment, and to have an associated skin disease. Treatments prescribed by dermatology clinics had the lowest aggravating rate, although improvement rates for family medicine clinics were also fairly high. This is the first study to investigate in detail the demographic features and characteristics of the treatment-seeking behaviors of acne patients in Asia

Quercetin, the active phenolic component in kiwifruit, prevents hydrogen peroxide-induced inhibition of gap-junction intercellular communication

We evaluated the effects of the two main kiwifruit cultivars (gold kiwifruit (GOK) and green kiwifruit (GRK)) and their active phenolic compound, quercetin, on H2O2-induced inhibition of gap-junction intercellular communication (GJIC) in WB-F344 rat liver epithelial cells. We found that both GOK and GRK protect WB-F344 cells from H2O2-induced inhibition of GJIC. The extracellular signal-regulated protein kinase 1/2 (ERK1/2)-connexin 43 (Cx43) signalling pathway is crucial for the regulation of GJIC, and both GOK and GRK blocked the H2O2-induced phosphorylation of Cx43 and ERK1/2 in WB-F344 cells. Quercetin alone attenuated the H2O2-mediated ERK1/2-Cx43 signalling pathway and consequently reversed H2O2-mediated inhibition of GJIC in WB-F344 cells. A free radical-scavenging assay using 1,1-diphenyl-2-picrylhydrazyl showed that the scavenging activity of quercetin was higher than that of a synthetic antioxidant, butylated hydroxytoluene, per mol, suggesting that the chemopreventive effect of quercetin on H2O2-mediated inhibition of ERK1/2-Cx43 signalling and GJIC may be mediated through its free radical-scavenging activity. Since the carcinogenicity of reactive oxygen species such as H2O2 is attributable to the inhibition of GJIC, GOK, GRK and quercetin may have chemopreventive potential by preventing the inhibition of GJI

Cyclooxygenase-2 and p53 Expression as Prognostic Indicators in Conventional Renal Cell Carcinoma

The aim of this study was to investigate the relationship of cyclooxygenase (COX)-2 and p53 expression with prognosis in patients with conventional renal cell carcinoma (RCC). Formalin-fixed, paraffin-embedded tissue sections of conventional RCC from 92 patients, who had undergone radical nephrectomy, were examined for COX-2 and p53 expression by immunohistochemistry and compared with clinicopathological variables. The COX-2 expression significantly correlated only with tumor size (p=0.049), whereas the p53 expression profoundly correlated with the TNM stage (p=0.024), M stage (p=0.001), and metastasis (synchronous or metachronous; p=0.004). The COX-2 overexpression did not significantly associate with p53 positivity (p=0.821). The survival rate of patients correlated with the p53 expression (p<0.0001) but not with the COX-2 expression (p=0.7506). Multivariate analyses indicated that tumor size, M stage, and p53 expression were independent prognostic factors for cancer-specific survival. The COX-2 expression was not an independent factor. These results show that the increased expression of p53 was associated with metastasis and a worse prognosis in conventional RCC, which suggests that p53 might have played an important role in the progression of conventional RCC. The increased expression of COX-2 was associated only with tumor size, but may not be an important prognostic factor in conventional RCC. No association was observed between COX-2 overexpression and p53 positivity in conventional RCC