700 research outputs found
Stimulate puppets’ law of motion in the natural relaxation An interview to puppet master and educator Mr. Tan Zhiyuan
Interview Time: February 12, 2015, at 4PM -10PM. Interview Venue: Tan Zhiyuan’s home. Interviewed by Wang Xiaoxin (hereinafter, WANG), lecturer of Shanghai Theatre Academy Puppet Program, M.A. of Peking University, Special Research Fellow of Yale University Drama School. Interview to Tan Zhiyuan (hereinafter, TAN), Former Vice Chair of the China National Puppet Arts Troupe, First-grade Puppeteer, Member of Chinese Dramatists Association, Member of Council of China Puppetry and Shadow Arts Association.Rod puppet is an important form of Chinese puppet. Its structureand performing techniques are quite different from that of marionette andhand puppet. Rod puppet can be manipulated by a main-rod (connectedto a puppet head) and two hand rods (connected to puppet’s hands),known as "three rods", and it is named as "rod" for its resemblance to oldman’s walking stick. In China, the most representative rod puppet troupe is China National Puppet Arts Troupe2, in which Mr. Tan used to work
Uncertain Programming for Network Revenue Management
The mathematical model for airline network seat inventory control problem is usually investigated to maximize the total revenue under some constraints such as capacities and demands. This paper presents a chance-constrained programming model based on the uncertainty theory for network revenue management, in which the fares and the demands are both uncertain variables rather than random variables. The uncertain programming model can be transformed into a deterministic form by taking expected value on objective function and confidence level on the constraint functions. Based on the strategy of nested booking limits, a solution method of booking control is developed to solve the problem. Finally, this paper gives a numerical example to show that the method is practical and efficient
CEO successor compensation: outside versus inside successions
We propose that outside CEO candidates will have greater bargaining power than insiders. As a result, outside CEO successors will likely receive greater total compensation than inside CEO successors. Outside successors, meantime, pose more risk to the hiring firm than inside successors due to higher information asymmetry. As a result, outside successor compensation packages are tilted towards more performance-related pay-at-risk, while inside successor packages have a higher percentage in salary. In addition, outside successors may want to utilize the structure of their compensation at their previous firm in their new contracts. Using a sample of 99 firms with outside successors who were not CEO in their prior firms, matched by industry and size to firms that hired inside candidates, we find evidence supporting these hypotheses
2D :a stable direct-bandgap semiconductor with record-breaking carrier mobility,
The Moore's law in the semiconducting industry has faltered as the
three-dimensional (3D) Si-based transistors has approached their physical limit
with the downscaling. The carrier mobility , critical to the device's
performance, will be degraded when the thickness of Si is scaled into several
nanometers. In contrast to the bulk counterpart, two-dimensional (2D)
semiconductors can be scaled into atomic-layer thickness without dangling
bonds, maintaining its intrinsic carrier mobility and going beyond the limits
of Si-based electronics. Hence, the development of novel 2D semiconducting
materials with high carrier mobility is the market demand as well as the
scientific challenge. Here, we successfully designed 2D with planar hypercoordinate motif. It possesses the perfect
planar skeleton with both pentacoordinate carbon and hexacoordinate boron
moieties, which is the first reported material with such multi-hypercoordinate
centers. Density functional theory (DFT) calculations prove that the monolayer has excellent structural and thermal stabilities
as well as mechanical properties. Further investigations reveal that the monolayer has a strong ultrahigh Fermi velocity (), suitable direct bandgap (1.97 eV), and high optical
absorption coefficient (). As a result, an unprecedented ultrahigh
room-temperature carrier mobility ()
with strong anisotropy is discovered, making monolayer
a revolutionary candidate for future electronic and photovoltaic applications.Comment: 16 pages, 4 figures, 1 tabl
DEVELOPING ARTIFICIAL MUCUS HYDROGEL THAT MIMICS CYSTIC FIBROSIS AIRWAY MUCUS
Cystic fibrosis (CF) is one of the most common genetic lung diseases caused by a mutation of the chloride regulator in airway cells, which leads to dysregulation of iron transport and airway dehydration. As a result, airway mucus in CF patients (i.e. CF sputum) is highly viscoelastic and hard to be cleared by physiological mucus clearance mechanism, thereby promoting chronic infection and inflammation. Previously, bacteria cell growth and neutrophil-mediated bacterial cell killing were studied with mucus solution prepared with different concentration of mucin which is the major macromolecular component of airway mucus. However, mucus solution does not recapitulate airway mucus on the account of failure to form physiological gel-like structures relevant to behaviors of bacteria and neutrophils. Thus, to investigate the effect of microstructure of mucus on these behaviors on the cellular and molecular levels, we developed artificial irreversible and bio-reducible mucus hydrogel with well-defined pore sizes and similar biochemical contents comparable to CF airway mucus, by chemically crosslinking porcine gastric mucin (PGM). Since CF patients are often treated with mucus-altering agents (i.e. mucolytics) to reduce the viscoelasticity of mucus, we not only evaluated the microstructure of artificial mucus hydrogel per se but also examined the mucolytic-mediated microstructural changes using multiple particle tracking method. The results here show that the microstructure and mucolytic-mediated microstructure changes of artificial bio-reducible mucus hydrogels are comparable to what were observed in CF sputum. And we also confirmed that bulk rheology of bio-reducible artificial mucus is comparable to that of CF sputum. In addition, mucolytic-mediated changes in bulk rheology properties of the mucus hydrogel and CF sputum were virtually identical. Furthermore, we investigated the biochemical properties of bio-reducible mucus hydrogel (i.e. mucin and, cysteines content), and lastly, the ability of bacteria to grow in artificial bio-reducible mucus hydrogel. These results show that the artificial bio-reducible mucus hydrogel is a promising model to investigate the effect of mucus microstructure on mucosal pathogenesis and innate immunity in CF airways
Histone deacetylases (HDACs) in XPC gene silencing and bladder cancer
Bladder cancer is one of the most common malignancies and causes hundreds of thousands of deaths worldwide each year. Bladder cancer is strongly associated with exposure to environmental carcinogens. It is believed that DNA damage generated by environmental carcinogens and their metabolites causes development of bladder cancer. Nucleotide excision repair (NER) is the major DNA repair pathway for repairing bulk DNA damage generated by most environmental carcinogens, and XPC is a DNA damage recognition protein required for initiation of the NER process. Recent studies demonstrate reduced levels of XPC protein in tumors for a majority of bladder cancer patients. In this work we investigated the role of histone deacetylases (HDACs) in XPC gene silencing and bladder cancer development. The results of our HDAC inhibition study revealed that the treatment of HTB4 and HTB9 bladder cancer cells with the HDAC inhibitor valproic acid (VPA) caused an increase in transcription of the XPC gene in these cells. The results of our chromatin immunoprecipitation (ChIP) studies indicated that the VPA treatment caused increased binding of both CREB1 and Sp1 transcription factors at the promoter region of the XPC gene for both HTB4 and HTB9 cells. The results of our immunohistochemistry (IHC) staining studies further revealed a strong correlation between the over-expression of HDAC4 and increased bladder cancer occurrence (p < 0.001) as well as a marginal significance of increasing incidence of HDAC4 positivity seen with an increase in severity of bladder cancer (p = 0.08). In addition, the results of our caspase 3 activation studies demonstrated that prior treatment with VPA increased the anticancer drug cisplatin-induced activation of caspase 3 in both HTB4 and HTB9 cells. All of these results suggest that the HDACs negatively regulate transcription of the XPC gene in bladder cancer cells and contribute to the severity of bladder tumors
The effect of caffeine on cisplatin-induced apoptosis of lung cancer cells
Background: Cisplatin is an important DNA-damaging anticancer drug that has been used to treat many cancer types. However, the effectiveness of cisplatin treatment diminishes quickly as cancer cells develop resistance to the drug, which eventually results in treatment failure. Caffeine is an ingredient contained in many food sources. Caffeine can inhibit activities of both ATM and ATR, two important protein kinases involved in DNA damage-induced cell cycle arrest and apoptosis. The effect of caffeine on cisplatin-based cancer treatment is not well known.
Methods: Caspase-3 activation and cell growth inhibition assays were used to determine the effect of caffeine on cisplatin-induced apoptosis and cell growth in lung cancer cells. Real time PCR, immunoblotting, and flow cytometry assays were used determine a mechanism through which the presence of caffeine increased cisplatin-induced apoptosis of the lung cancer cells.
Results: Our caspase-3 activation studies demonstrated that the presence of caffeine increased the cisplatin-induced apoptosis in both HTB182 and CRL5985 lung cancer cells. Our cell growth inhibition studies indicated that the presence of caffeine caused a more increase for cisplatin-induced cell growth inhibition. The results obtained from our real time PCR and western blot studies revealed that the presence of caffeine increased cisplatin-induced expression of the PUMA pro-apoptotic protein in these lung cancer cells. The results of our protein phosphorylation studies indicated that the presence of caffeine caused a decrease in CHK1 phosphorylation at Ser317/Ser345but an increase in ATM phosphorylation at Ser1981 in the lung cancer cells treated with cisplatin. In addition, our flow cytometry studies also revealed that the presence of caffeine caused an increase in G1 cell population but a decrease for cisplatin-induced cell cycle arrests at the S and the G2 checkpoints in HTB182 and CRL5985 cells respectively.
Conclusion: Our results suggest that the presence of caffeine increases the cisplatin-induced lung cancer cell killings by inhibiting ATR but inducing ATM activation, resulting in an increase in expression of PUMA protein and an increase in apoptosis
Does experience matter? CEO successions by former CEOs
Purpose - This paper aims to investigate an interesting yet mostly ignored distinction within external CEO successions: outside successors who have previous CEO experience and those who do not. It examines stock market reaction, compensation and firm performance prior and post-succession.
Design/methodology/approach - The authors used an event study, Patell Z-statistic and Rank Z-statistic to test cumulative abnormal return before and after the successions. They also used probit and OLS regressions to examine firm performance and CEO compensation prior and post-succession.
Findings - The authors find that the stock market reacts positively to the hiring of an outsider who is an exCEO. Compared with firms that hire non-exCEOs, firms that hire exCEOs had higher debt ratios and greater bankruptcy chances pre-succession, but post-succession, these firms still have worse financial performances. Non-exCEOs come from better performing firms than exCEOs. There is no consistently significant difference in compensation between an exCEO and a non-exCEO, though the compensation for both increases significantly from that of the predecessors and that of their previous positions.
Research limitations/implications - Future research could focus on the cost-benefit tradeoff of hiring an exCEO. It would be interesting to examine the role of the board of directors in assessing this cost-benefit tradeoff and determining the optimal choice for the firm. An important aspect that has not been sufficiently examined in the literature is the CEO fit. Hiring an exCEO may not always be the right choice for the firm. Another area for future research could examine how the post-succession performance is affected by exCEO tenure in previous CEO position(s) and whether the exCEO worked in several industries or in the same industry.
Practical implications - This paper also has implications for the board of directors. There seems to be a negative transfer of human capital when it comes to hiring exCEOs. The human capital theory suggests that job-specific experience positively relates to job performance. According to Hamori and Koyuncu, prior CEO experience may lead to the formation of knowledge corridors and decision-making templates that make it difficult for individuals to take in inconsistent information or take actions that are different from past ones in a changed context. This, in turn, undermines performance . Boards of directors should put more effort into considering inside relay successions and should be cautious when hiring an outsider who has prior CEO experience. A best-of-both-worlds scenario may be for boards to hire exCEOs into top executive positions, such as COO and/or president, so as to give them a chance to be groomed for the top position and familiarize themselves with the firm while still benefiting from their prior CEO experience.
Originality/value - There is very little research on the distinction between outside CEOs with previous CEO experience and those with no such experience. This paper tries to shed some light on this important issue in corporate governance in order to explain why boards of directors would hire an outsider with or without previous CEO experience
Design of gate-tunable graphene electro-optical reflectors based on an optical slot-antenna coupled cavity
The unique properties of graphene offer an exciting opportunity towards tunable photonic surfaces for flexible devices. In this paper, we design a gate-tunable, free-space graphene electro-optical reflector based on cavity resonator structures. We firstly calculate the graphene refractive index n and k as a function of Fermi level and external gating voltage. Then, we designed the structure of the single-layer graphene reflective resonator by carefully selecting suitable materials and device parameters to maximize the reflectance differences before and after electro-optical tuning. We also developed a theoretical model to discuss this system based on the optical transition matrix method. Moreover, we used field enhancement to further increase the reflectance differences by incorporating Sn nanodots based optical slot-antenna coupled cavities. The maximum broadband, incident angle insensitive reflectance differences could reach 28% with an extinction ratio of 1.62 dB at a low insertion loss of 0.45 dB, and the spectral range is tunable by changing the optical cavity length. We also used an indium tin oxide layer as part of the optical cavity and the electrode simultaneously to reduce the voltage applied. To our best knowledge, this work is the first one on tunable two-dimensional (2D) material reflectors for free-space applications, apart from using liquid crystals or magnetic metasurfaces. This new design of tunable 2D electro-optical reflectors also reduces the complexity of fabrication steps, having promising applications in tunable flexible photonic surfaces and devices for variable optical attenuators and light detection and ranging systems
- …