Consistent Monitoring of Cointegrating Relationships: The US Housing Market and the Subprime Crisis

We propose a consistent monitoring procedure for structural change in a cointegrating relationship. The procedure is inspired by Chu et al. (1996) by being based on parameter estimation on a prebreak ‘calibration’ period. We use three modified least squares estimators to obtain nuisance parameter‐free limiting distributions. We study the asymptotic and finite sample properties of the procedures and finally apply the approach to monitor two‐fundamentals‐driven US housing prices cointegrating relationships over the period 1976:Q1–2010:Q4 using the data of Anundsen (2015). Depending on the relationship considered and the estimation method used, a break point is detected as early as 2003:Q2, that is, well before US housing prices started to fall in 2007.     

Automated Spore Measurements Using Microscopy,Image Analysis,and Peak Recognition of Near-Monodisperse Aerosols

Rapid detection of airborne fungal and bacterial spores would enable public agencies to respond quickly and appropriately to intentional releases of hazardous aerosols. Automated analysis of microscope images and automated detection of near-monodisperse peaks in aerosol size distribution data offer complementary approaches to traditional methods for the identification and counting of fungal and bacterial spores. First, spores of the fungus Scopulariopsis brevicaulis were aerosolized in a chamber and then collected with a slit impactor; later, digital microscope images were analyzed manually to determine spore cluster distributions. The images also were analyzed with ImageJ, a program that automatically outlined objects and measured Feret's diameter, area, perimeter, and circularity. These characteristics were used to identify spore clusters automatically using two data analysis methods. Second, a computer program was developed to discriminate near-monodisperse bioaerosol peaks from those for polydisperse ambient particulate matter (PM) and was successfully tested using simulated and real aerosol mixtures. The observed agreement between manual and automated spore counts and the ability to detect spore peaks suggest that it may be possible to develop a system to recognize intentional releases rapidly through examination of particle morphology and size distributions. The peak detection procedure is potentially the fastest technique when used with real-time instrument data, but assumes that intentional releases would consist of large numbers of uniformly sized particles in the respirable size range.

Copyright 2012 American Association for Aerosol Research     

Identification of New N‐Acylhomoserine Lactone Signalling Compounds of Dinoroseobacter shibae DFL‐12T by Overexpression of luxI Genes

Bacteria of the Roseobacter clade are widespread in the ocean and occur in many different habitats. In the genome of Dinoroseobacter shibae DFL‐12, luxI homologous genes that encode synthases responsible for the formation of N‐acylhomoserine lactones (AHLs) have been described. These compounds are known autoinducers that regulate several biological traits—namely, flagella formation and cell differentiation—in D. shibae through quorum sensing. The AHLs produced by D. shibae mainly consisted of N‐octadecadienoylhomoserine lactone (C18:2‐AHL) and N‐octadecenoylhomoserine lactone (C18:1‐HSL). In the wild type these AHLs are synthesized only in low abundance. The luxI genes were therefore expressed in Escherichia coli; this resulted in the formation of AHLs mostly different from those found in the D. shibae wild type. A luxI₁‐deficient mutant of D. shibae was then reprovided with an overexpressed luxI₁ gene. This strain produced large amounts of C18:2‐AHL and C18:1‐AHL, allowing full characterization of these compounds by mass spectrometric techniques and derivatization. Synthesis of the proposed structures confirmed that the major compound is (2E,11Z)‐N‐octadeca‐2,11‐dienoylhomoserine lactone ( 6 , C18:2‐HSL), accompanied by (Z)‐N‐octadec‐11‐enoylhomoserine lactone ( 5 , C18:1‐HSL). AHL 6 has not been reported before from other organisms and contains an unusual 2E double bond.     

Effect of Solvent Content on the Separation and the Energy Consumption of Extractive Distillation Columns

This article sets out to evaluate the effect of solvent content in the extractive section on the separation efficiency and energy consumption of extractive distillation columns. Contrary to the classical approach, the proposed approach enables a simultaneous evaluation of the effect of the major decision variables (reflux ratio, solvent flow rate, and the number of stages of the extractive section [NSE]). The procedure allows calculating the minimum solvent flow rate for the separation and the minimum specific energy consumption. The results show that the minimum specific energy consumption is obtained for the minimum reflux ratio and not for the minimum solvent flow rate. Moreover, the results show that it is not always the case that a larger NSE results in lower energy consumption. Due to its industrial importance, the dehydration of aqueous mixtures of ethanol using ethylene glycol as solvent has been chosen as a case study.     

Passive Aerosol Sampler. Part I: Principle of Operation

A method has been developed to estimate average concentrations and size distributions with a miniature passive aerosol sampler. To use the passive sampler, one exposes it to an environment for a period of hours to weeks. The passive sampler is intended to monitor ambient, indoor, or occupational aerosols and has potential utility as a personal sampler. The sampler is inexpensive and easy to operate and is capable of taking long-term samples to investigate chronic exposures. After sampling, the passive sampler is covered and brought to the lab. Scanning electron microscopy (SEM) and automated image analysis are used to count and size collected particles with d_p     

Solid Fat Content Estimation by Differential Scanning Calorimetry: Prior Treatment and Proposed Correction

The objective of this work was to develop a corrected method for solid fat content estimation by differential scanning calorimetry (DSC), as important differences are usually observed between the results given by DSC and pulsed nuclear magnetic resonance (NMR). Cold storage after full melting of fats was necessary to avoid the appearance of exothermic peaks in the modulated temperature DSC thermograms, in order to make an appropriate estimation of melting energy. Different fats were analyzed by NMR and DSC, obtaining considerably higher solid fat content values with the latter, uncorrected method. These differences were attributed to the fact that consumed energy per unit of melted mass tends to increase with the increase of the melting temperature of each fraction of the fats. A linear correlation between melting enthalpy and melting point of different triglycerides was used to estimate the energy per unit of mass consumed at each temperature. From these data, an estimated transformation of melting energy into melted mass was performed and new solid fat content values were calculated. The results obtained from this correction were much closer to the measurements made by NMR, in comparison to the uncorrected DSC method.     

Effect of compression on the performance of a HT-PEM fuel cell

This paper shows by thorough electrochemical investigation that (1) the performances of high-temperature polymer electrolyte fuel cell membrane electrode assemblies of three suppliers are differently affected by compressive forces. (2) Membrane thickness reduction by compressive pressure takes place less than expected. (3) A contact pressure cycling experiment is a useful tool to distinguish the impact of compression on the contact resistances bipolar plate/gas diffusion layer (GDL) and GDL/catalytic layer. A detailed visual insight into the structural effects of compressive forces on membrane and gas diffusion electrode (GDE) is obtained by micro-computed X-ray tomography (μ-CT). μ-CT imaging confirms that membrane and GDEs undergo severe mechanical stress resulting in performance differences. Irreversible GDL deformation behavior and pinhole formation by GDL fiber penetration into the membrane could be observed.     

Bulk Sediment and Diatom Silica Carbon Isotope Composition from Coastal Marine Sediments off East Antarctica

Organic carbon occluded in diatom silica is assumed to be protected from degradation in the sediment. δ¹³C from diatom carbon (δ¹³C_(diatom)) therefore potentially provides a signal of conditions during diatom growth. However, there have been few studies based on δ¹³C_(diatom). Numerous variables can influence δ¹³C of organic matter in the marine environment (e.g., salinity, light, nutrient and CO₂ availability). Here we compare δ¹³C_(diatom) and δ¹³C_(TOC) from three sediment records from individual marine inlets (Rauer Group, East Antarctica) to (i) investigate deviations between δ¹³C_(diatom) and δ¹³C_(TOC), to (ii) identify biological and environmental controls on δ¹³C_(diatom) and δ¹³C_(TOC), and to (iii) discuss δ¹³C_(diatom) as a proxy for environmental and climate reconstructions. The records show individual δ¹³C_(diatom) and δ¹³C_(TOC) characteristics, which indicates that δ¹³C is not primarily controlled by regional climate or atmospheric CO₂ concentration. Since the inlets vary in water depths offsets in δ¹³C are probably related to differences in water column stratification and mixing, which influences redistribution of nutrients and carbon within each inlet. In our dataset changes in δ¹³C_(diatom) and δ¹³C_(TOC) could not unequivocally be ascribed to changes in diatom species composition, either because the variation in δ¹³C_(diatom) between the observed species is too small or because other environmental controls are more dominant. Records from the Southern Ocean show depleted δ¹³C_(diatom) values (1–4 ‰) during glacial times compared to the Holocene. Although climate variability throughout the Holocene is low compared to glacial/interglacial variability, we find variability in δ¹³C_(diatom), which is in the same order of magnitude. δ¹³C of organic matter produced in the costal marine environment seems to be much more sensitive to environmental changes than open ocean sites and δ¹³C is of strongly local nature.     

Identification and Structure–Activity Relationship Studies of Small‐Molecule Inhibitors of the Methyllysine Reader Protein Spindlin1

The methyllysine reader protein Spindlin1 has been implicated in the tumorigenesis of several types of cancer and may be an attractive novel therapeutic target. Small‐molecule inhibitors of Spindlin1 should be valuable as chemical probes as well as potential new therapeutics. We applied an iterative virtual screening campaign, encompassing structure‐ and ligand‐based approaches, to identify potential Spindlin1 inhibitors from databases of commercially available compounds. Our in silico studies coupled with in vitro testing were successful in identifying novel Spindlin1 inhibitors. Several 4‐aminoquinazoline and quinazolinethione derivatives were among the active hit compounds, which indicated that these scaffolds represent promising lead structures for the development of Spindlin1 inhibitors. Subsequent lead optimization studies were hence carried out, and numerous derivatives of both lead scaffolds were synthesized. This resulted in the discovery of novel inhibitors of Spindlin1 and helped explore the structure–activity relationships of these inhibitor series.