Spatial Economic Theory of Pollution Control under Stochastic Emissions

This paper examines the eectiveness of environmental policies in curtailing pollution of a rm which is operating in a space economy under stochastic emissions. We consider a general n-input planar space production-location model, in which the output is produced jointly with the byproduct pollution. Although production is nonstochastic, the resulting pollution emission is assumed to have a random component, and the polluting rm must make its production and location decisions before the uncertainty is resolved. We provide some propositions concerning the comparative statics of the polluting rm's location choices, urban pollution concentration, and the relative impact of regulation via emission taxes to that of emission standards.location theory, pollution control, emission uncertainty

Spatial Monopoly Pricing in a Stochastic Environment

This paper reexamines the welfare implications of three pricing regimes (mill, uniform and discriminatory) for a monopoly in a stochastic environment. It con-siders a risk-averse monopolist faces two markets with stochastic and linear demands. The monopolist is assumed to commit to an irreversible price in each market before the uncertainty is resolved. Several unconventional results are shown to be triggered by the presence of demand uncertainty. The reason for the reversal of orthodox intuition is the asymmetry in the risk chacteristics of the markets and the willingness of the monopolist to trade increased level of expected prots for reduced risk.spatial pricing, monopoly, demand uncertainty

Onset of natural convection in gas-gas system induced by bottom-up transient mass diffusion

The onset of convection induced by transient mass diffusion in a stationary gas was succesfully predicted with transient instability theory and simulated using a computational fluid dynamics (CFD) scheme. 2D time-dependent simulations were conducted for bottom-up diffusion of a light gas in a stagnant heavy gas. The results of simulations were used to calculate the transient Rayleigh number adopted from the theory of Tan and Thorpe (1996 and 1999). The average transient maximum Rayleigh number from simulations is 707, which is close to the theoretical value of 817 for analogous bottom heating with constant heat flux. The simulated critical times of the onset of convection were in reasonably good agreement with the predicted values from theory

What is the value of built heritage? Assessing spillover effects of conserving historic sites in Singapore

10.1016/j.landusepol.2019.104393Land Use Policy9110439

Fluorescent quantitation method for differentiating the nativity of green fluorescent protein

A gel imaging method was employed to quantitate the GFP that had been subjected to denaturation and degradation treatments. This method is able to differentiate the nativity of GFP by relating the observed changes in the position of fluorescent bands which is unable to be detected using the spectrofluorometric method

Detection of hepatitis B virus core antigen by phage display mediated TaqMan real-time immuno-PCR

The core antigen (HBcAg) of hepatitis B virus (HBV) is one of the markers for the identification of the viral infection. The main purpose of this study was to develop a TaqMan real-time detection assay based on the concept of phage display mediated immuno-PCR (PD-IPCR) for the detection of HBcAg. PD-IPCR combines the advantages of immuno-PCR (IPCR) and phage display technology. IPCR integrates the versatility of enzyme-linked immunosorbent assay (ELISA) with the sensitivity and signal generation power of PCR. Whereas, phage display technology exploits the physical association between the displayed peptide and the encoding DNA within the same phage particle. In this study, a constrained peptide displayed on the surface of an M13 recombinant bacteriophage that interacts tightly with HBcAg was applied as a diagnostic reagent in IPCR. The phage displayed peptide and its encoding DNA can be used to replace monoclonal antibody (mAb) and chemically bound DNA, respectively. This method is able to detect as low as 10 ng of HBcAg with 108 pfu/ml of the recombinant phage which is about 10,000 times more sensitive than the phage-ELISA. The PD-IPCR provides an alternative means for the detection of HBcAg in human serum samples

The release of hepatitis B core antigen from Escherichia coli by batch mode bead milling

The performance of a batch model bead mill on the release of hepatitis B core antigen (HBcAg) from Escherichia coli was investigated in this study. The operating parameters examined were impeller tip speed (8–14 m/s), biomass concentration [5–20% (w/v)] and bead loading [65–80% (v/v)]. The highest yield (24.3 mg/g cell) and rate constant (0.471 l/min) of HBcAg release were achieved at impeller tip speed of 14 m/s. However, the high-shear stress under these operating conditions caused damage of the HBcAg. The highest yield (22.7 mg/g cell) and rate constant (0.344 l/min) of HBcAg release were observed at biomass concentration of 20% (w/v). There was no significant effect of bead loading on the performance of bead milling being observed. In conclusion, the optimal operating condition for the release of HBcAg was at bead loading of 75% (v/v), biomass concentration of 20% (w/v) and impeller tip speed of 10 m/s

Recovery of histidine-tagged nucleocapsid protein of Newcastle disease virus using immobilised metal affinity chromatography

An immobilised metal affinity packed bed adsorption chromatography (IMA-PBAC) for the purification of recombinant nucleocapsid protein (NP) of Newcastle disease virus (NDV) directly from clarified feedstock was developed. The XK 16/20 (i.d. = 16 mm) was used as a packed bed column and Streamline chelating adsorbent immobilised with Ni2+ ion was used as IMA adsorbent. This purification method has resulted in a 59% adsorption and 5.6% recovery of NP protein. Adsorbed NP proteins were successfully recovered using a two-step elution protocol which employed elution buffer 1 containing 50 mM imidazole to eliminate contaminating proteins and elution buffer 2 containing 350 mM imidazole to recover the NP protein at pH 8 with flow velocity of 10 cm h−1. About 70% of the adsorbed NP protein was eluted. The purity of the recovered NP protein was about 70% and the volume of processing fluid was reduced by a factor of 4. The antigenic features of purified NP proteins were confirmed by enzyme-linked immunosorbent assay (ELISA) analysis

Invariance Principles and Observability in Switched Systems with an Application in Consensus

Using any nonnegative function with a nonpositive derivative along trajectories to define a virtual output, the classic LaSalle invariance principle can be extended to switched nonlinear time-varying (NLTV) systems, by considering the weak observability (WO) associated with this output. WO is what the output informs about the limiting behavior of state trajectories (hidden in the zero locus of the output). In the context of switched NLTV systems, WO can be explored using the recently established framework of limiting zeroing-output solutions. Adding to this, an extension of the integral invariance principle for switched NLTV systems with a new method to guarantee uniform global attractivity of a closed set (without assuming uniform Lyapunov stability or dwell-time conditions) is proposed. By way of illustrating the proposed method, a leaderless consensus problem for nonholonomic mobile robots with a switching communication topology is addressed, yielding a new control strategy and a new convergence result