Investment and Consumption with Regime-Switching Discount Rates

This paper considers the problem of consumption and investment in a financial market within a continuous time stochastic economy. The investor exhibits a change in the discount rate. The investment opportunities are a stock and a riskless account. The market coefficients and discount factor switch according to a finite state Markov chain. The change in the discount rate leads to time inconsistencies of the investor's decisions. The randomness in our model is driven by a Brownian motion and a Markov chain. Following Ekeland and Pirvu we introduce and characterize the subgame perfect strategies. Numerical experiments show the effect of time preference on subgame perfect strategies and the pre-commitment strategies.Comment: arXiv admin note: substantial text overlap with arXiv:1107.189

Acoustic Needs of Older People in the Outdoor Environment of Residential Communities: A Case Study in China

This study examines the acoustic needs of older people in an outdoor environment to design outdoor spaces according to their needs. Using the grounded theory approach, we selected and interviewed 16 older people from four residential communities in China. The acoustic needs of older people in an outdoor environment are established in terms of sound preference, quietness, acoustic variability, acoustic comfort, subjective loudness, sound rhythm, sound clarity, and sound sensitivity. The findings show that older people (a) attach importance to quietness when considering sound preference, (b) prefer taking a walk in an overall quiet environment, although sometimes a lively environment, (c) chose to conduct their activities in an environment with low variation in sound, (d) rate the comfort of their overall acoustic environment highly, (e) show little need for subjective loudness as long as the sounds are not ones they dislike, (f) generally prefer relatively rhythmic sound sources, (g) did not have a significant need for sound clarity, and (h) are tolerant of outdoor acoustic environments and did not pay too much attention to certain sounds. These findings can provide direction for better outdoor space designs in communities, to suit older people, and to create age-friendly cities

Cell-based screening of antistress activity of some phytochemicals: Identification, validation, and relevance to old-age related pathologies

Background: A variety of environmental stresses have been shown to contribute to poor quality of life, tissue dysfunctions and ailments including metabolic disorders, cognitive impairment, and accelerated aging. Oxidative stress (an imbalance between the production and processing of highly reactive oxygen species) is largely associated with these phenotypes. Whereas drug development and disease therapeutics have advanced remarkably in last three decades, there are still limited options for stress management. Since the later can effectively decrease the disease burden, we aimed to screen phytochemicals with anti-oxidative stress activity using cell-based assays. Methods: Brain-derived cells were subjected to chemical models of oxidative (paraquat), metal (cadmium nitrate) or hypoxia (cobalt chloride) stresses. Stressed cells were allowed to recover either in the control or phytochemical supplemented culture medium. Cell survival and protein expression/signaling were analyzed to select the useful compounds and/or plant extracts. Results: Cells subjected to paraquat stress showed decrease in their viability. Three rounds of blind screening of the 24 phytochemicals resulted in identification of 5 compounds that caused better recovery of cells. The selected compounds were examined for their ability for protection against metal and hypoxia stresses induced by cadmium nitrate and cobalt chloride, respectively. Based on these 3D-anti stress protection ability, Withanone (Wi-N) and triethylene glycol (TEG) were selected for molecular validation. We found that whereas stress caused increase in (i) apoptosis (ii) ROS accumulation coupled with mitochondrial depolarization (iii) DNA double-strand break (iiii) protein aggregation, the selected compounds and the Ashwagandha extracts (known to possess these compounds) caused remarkable protection. Furthermore, both Wi-N and TEG caused differentiation of C6 glioblastoma and IMR-32 neuroblastoma as evidenced by the respective differentiated cell morphology and increased expression of biomarkers. Conclusion: The results suggested that Wi-N, TEG, their mixture, and the natural resource (Ashwagandha) possess potent antistress activity that may be useful for management of old-age-related ailments

miRAS: a data processing system for miRNA expression profiling study

<p>Abstract</p> <p>Background</p> <p>The study of microRNAs (miRNAs) is attracting great considerations. Recent studies revealed that miRNAs play as important regulators of gene expression and some even as cancer players or inhibitors. Many studies try to discover new miRNAs and reveal the miRNA expression profile in cancer using a SAGE-based total RNA clone method. However, the data processing of this method is labor-intensive with several different biological databases and more than ten data processing steps involved.</p> <p>Results</p> <p>With miRAS, miRNAs and possible miRNA candidates contained in the submitted sequencing data were obtained together with their expression profile. The functions of known and predicted miRNAs were then analyzed by miRNA target prediction followed by target gene annotations. Finally, to extract the biological significance of the miRNAs in the samples, further annotations of the known miRNA and target genes were performed by collecting the public expression datasets of miRNA and target genes in normal and cancer tissues.</p> <p>Conclusion</p> <p>We introduce a web-based analysis platform called miRNA Analysis System (miRAS), for processing and analyzing of the sequence data obtained from the total RNA clone method. The system was built on generalizing the study of a liver cancer cell line total RNA sequencing project. miRAS is freely available on the web.</p

Inhibition of lipid accumulation in hepatocytes by unique Ashwagandha extracts

Introduction: Ashwaganda (Withania Somnifera) is a popular ayurvedic herb, trusted for a variety of health benefits in Indian traditional home medicine system. Steroidal lactones, Withaferin A (Wi-A) and Withanone (Wi-N), have been characterized as its major bioactives with a variety of bioactivities. We investigated the effect of Ashwagandha extracts on steatosis, abnormal retention of fat within a cell or organ that often affects liver as non-alcoholic fatty liver disease (NAFLD). Methods: We prepared extracts from Ashwagandha that varied in their Wi-A and Wi-N content. Cytotoxicity of these extracts on human hepatocytes (Huh-7 and Suit-2) was evaluated by cell viability assays. Nontoxic doses were used to treat the cells subjected to activated lipid accumulation by palmitic acid (PA). The lipolygenesis was evaluated by Oil Red O and triglyceride (TG) assays, and the expression of molecules involved in this process. Results and Discussions: The four kinds of extracts with different amounts of total withanolides and Wi-A:Wi-N ratio were generated. Cells were treated with PA to induce lipid accumulation. We found that in cells pre-treated with specific Ashwahandha extracts, TG accumulation was decreased. Of note, Sterol regulatory element-binding protein-1c (SREBP-1c), and its downstream effector-Fas, the key regulators of lipogenesis showed downregulation in specific extract-treated cells. Furthermore, the expression of PPARγ, a key factor involved in hepatic lipogenesis, showed decrease in cells treated with some of these extracts. Conclusion: Ashwagandha extracts may provide a useful natural resource with anti-steatosis activity, maintaining liver health and NAFLD prevention

Molecular insights to the dose-dependent activities of Ashwagandha extracts

Background: Stress is an inevitable component of life. Several herbs are known for their health supporting effects that range from treatment of stress, common cold to cancer. We investigated the dose-dependent effect of Ashwagandha (Withania somnifera) extracts on human normal and cancer cells, and have attempted to resolve the molecular mechanisms of their antistress activities. Methods: Ashwagandha extracts were chemically profiled by HPLC. Cytotoxicity was determined by viability assays. Biochemical and immunoimaging assays were performed using specific antibodies. Results: Human normal cells treated with low doses of the leaf extract or purified withanolides (Withaferin A or Withanone) showed no toxicity. Such non-toxic doses were selected for antistress, neurodifferentiation and neuroregenerative assays. We found that whereas normal cells exposed to oxidative and UV stresses showed poor viability/growth arrest/apoptosis, cells treated with low doses of Ashwagandha extracts were protected. Brain-derived cells exposed to glutamate and scopolamine stresses showed protection and strong differentiation as marked by expression of neurodifferentiation markers. Muscle-derived cells cultured in low doses of extract showed muscle differentiation as marked by expression of muscle differentiation markers. Most recently, using computational tools, we examined potential of Ashwagandha for anti-SARS-CoV2 virus activity, and found that most of the Ashwagandha Withanolides have potential to block cell surface receptors (ACE2 and TMPRSS2) that are involved in entry of virus to human cells. Furthermore, Ashwagandha treated cells showed decrease in ACE2 and TMPRSS2 expression suggesting its potential in blocking virus infection. Conclusion: Ashwagandha extracts and withanolides possess useful bioactivities

A Multiperiod Equilibrium Pricing Model

We propose an equilibrium pricing model in a dynamic multiperiod stochastic framework with uncertain income. There are one tradable risky asset (stock/commodity), one nontradable underlying (temperature), and also a contingent claim (weather derivative) written on the tradable risky asset and the nontradable underlying in the market. The price of the contingent claim is priced in equilibrium by optimal strategies of representative agent and market clearing condition. The risk preferences are of exponential type with a stochastic coefficient of risk aversion. Both subgame perfect strategy and naive strategy are considered and the corresponding equilibrium prices are derived. From the numerical result we examine how the equilibrium prices vary in response to changes in model parameters and highlight the importance of our equilibrium pricing principle

Tunable nonlinear optical bistability based on Dirac semimetal in photonic crystal Fabry-Perot cavity

In this paper, we study the nonlinear optical bistability (OB) in a symmetrical multilayer structure. This structure is constructed by embedding a nonlinear three-dimensional Dirac semimetal (3D DSM) into a solution filled one-dimensional photonic crystal Fabry-Perot cavity. OB stems from the third order nonlinear conductivity of 3D DSM and the local field of resonance mode could enhance the nonlinearity and reduce the thresholds of OB. This structure achieves the tunability of OB due to that the transmittance could be modulated by the Fermi energy. OB threshold and threshold width could be remarkably reduced by increasing the Fermi energy. Besides, it is found that the OB curve depends heavily on the angle of incidence of the incoming light, the structural parameters of the Fabry-Perot cavity, and the position of 3D DSM inside the cavity. After parameter optimization, we obtained OB with a threshold of 106 V/m. We believe this simple structure provides a reference idea for realizing low threshold and tunable all optical switching devices. Keywords: Optical bistability, Dirac semimetal, Fabry-Perot cavity