Understanding Joint Retirement.

Evidence from different sources shows that spouses' retirement decisions are correlated. Retirement policies affecting individuals in couples are therefore also likely to affect behavior of their spouses. It is therefore important to account for joint features in modeling retirement. This paper studies a structural collective model of labor supply and retirement of both partners in a couple with interdependent preferences, imperfect knowledge of preferences of the spouse, and subjective expectations about the future. We propose a novel method to estimate preferences and the intra-household bargaining process, which relies on stated preferences data collected in the Health and Retirement Study. Respondents were asked to choose between hypothetical retirement trajectories describing the retirement ages and replacement rates of both spouses from three perspectives: considering their own preferences only, the preferences of their spouse only, or the most likely decision for the household. With these data, all model parameters are identified and potential sources of joint retirement can be disentangled. Our results suggest that males misperceive their wives' preferences, overestimating their disutility of work. Our estimates correct for this. We find strong positive correlations between preferences for joint leisure (leisure complementarity) of the two partners. Counterfactual simulations with stylized retirement paths suggest that the leisure complementarities explain a substantial part of joint retirement, much more than correlation in unobserved heterogeneity or potential wage rates.

Method for isolation of both lactose-fermenting and - non-fermenting Escherichia albertii strains from stool samples.

Initially, Escherichia albertii has been described as a non-lactose fermenting bacterium and methods used to isolate it were first based on this phenotypic property. However, a recent study showed a variable lactose fermentation phenotype for E. albertii suggesting that this microorganism could have been underestimated by previous studies using isolation methods based on lactose fermentation. In this study, we present a method for the isolation and identification of both lactose fermenting and non-fermenting-E. albertii cells in stool samples, said method combining culture and isolation on mEA agar, an indole test, as well as an E. albertii-specific PCR assay for formal species identification. The ability of the procedure to detect E. albertii strains was verified using 19 E. albertii strains and 132 non-E. albertii strains representing 88 species of different origins majoritary belonging to the Enterobacteriaceae family. All indole-positive white colonies grown on mEA agar were subjected to E. albertii-specific PCR amplification; all E. albertii strains tested were detected with this assay and none of the non-E. albertii strains tested was detected. To demonstrate the ability of the procedure to directly detect E. albertii in stool samples, E. albertii-inoculated stools were tested and for all inoculated samples, E. albertii colonies were easily detected and identified. The present study provides a method enable to recover both lactose-fermenting and -non-fermenting E. albertii strains from clinical samples. This method could help to provide a better portrait of the prevalence and pathogenicity of E. albertii in clinical samples.

Individual survival curves comparing subjective and observed mortality risks.

We compare individual survival curves constructed from objective (actual mortality) and elicited subjective information (probability of survival to a given target age). We develop a methodology to estimate jointly subjective and objective individual survival curves accounting for rounding on subjective reports of perceived survival. We make use of the long follow-up period in the Health and Retirement Study and the high quality of mortality data to estimate individual survival curves that feature both observed and unobserved heterogeneity. This allows us to compare objective and subjective estimates of remaining life expectancy for various groups and compare welfare effects of objective and subjective mortality risk using the life cycle model of consumption. We find that subjective and objective hazards are not the same. The median welfare loss from misperceptions of mortality risk when annuities are not available is 7% of current wealth at age 65 whereas more than 25% of respondents have losses larger than 60% of wealth. When annuities are available and exogenously given, the welfare loss is substantially lower.

CRENAME, A Molecular Microbiology Method Enabling Multiparametric Assessment of Potable/Drinking Water.

The microbial assessment of potable/drinking water is done to ensure that the resource is free of fecal contamination indicators or waterborne pathogens. Culture-based methods for verifying the microbial safety are limited in the sense that a standard volume of water is generally tested for only one indicator (family) or pathogen.In this work, we describe a membrane filtration-based molecular microbiology method, CRENAME (Concentration Recovery Extraction of Nucleic Acids and Molecular Enrichment), exploiting molecular enrichment by whole genome amplification (WGA) to yield, in less than 4 h, a nucleic acid preparation which can be repetitively tested by real-time PCR for example, to provide multiparametric presence/absence tests (1 colony forming unit or microbial particle per standard volume of 100-1000 mL) for bacterial or protozoan parasite cells or particles susceptible to contaminate potable/drinking water.

Portable devices and mobile instruments for infectious diseases point-of-care testing.

INTRODUCTION: Rapidity, simplicity, and portability are highly desirable characteristics of tests and devices designed for performing diagnostics at the point of care (POC), either near patients managed in healthcare facilities or to offer bioanalytical alternatives in external settings. By reducing the turnaround time of the diagnostic cycle, POC diagnostics can reduce the dissemination, morbidity, and mortality of infectious diseases and provide tools to control the global threat of antimicrobial resistance. Areas covered: A literature search of PubMed and Google Scholar, and extensive mining of specialized publications, Internet resources, and manufacturers' websites have been used to organize and write this overview of the challenges and requirements associated with the development of portable sample-to-answer diagnostics, and showcase relevant examples of handheld devices, portable instruments, and less mobile systems which may or could be operated at POC. Expert commentary: Rapid (<1 h) diagnostics can contribute to control infectious diseases and antimicrobial resistant pathogens. Portable devices or instruments enabling sample-to-answer bioanalysis can provide rapid, robust, and reproducible testing at the POC or close from it. Beyond testing, to realize some promises of personalized/precision medicine, it will be critical to connect instruments to healthcare data management systems, to efficiently link decentralized testing results to the electronic medical record of patients.

The GenePOC Platform, a Rational Solution for Extreme Point-of-Care Testing.

Extreme point-of-care (POC) testing for infections, as performed (endured) in low-resource settings, developing countries, tropical areas, or in conditions following emergency crises or natural disasters, must be undertaken under environmental, logistic, and societal conditions which impose a significant deal of stress on local human populations and healthcare providers. For disease diagnostics or management, simple and robust biomedical equipment and reagents are required and needed. This chapter aims to overview some of these stresses (requirements) and intends to describe some of the solutions already engineered at the heart of centripetal (centrifugal) microfluidic platforms such as that of GenePOC Inc. to enable rapid, robust, and reproducible nucleic acid-based diagnostics of infectious diseases, to better control the morbidity and mortality of infections and the expanding threat posed by antimicrobial resistance.

Abilities of the mCP Agar method and CRENAME alpha toxin-specific real-time PCR assay to detect Clostridium perfringens spores in drinking water.

We first determined the analytical specificity and ubiquity (i.e., the ability to detect all or most strains) of a Clostridium perfringens-specific real-time PCR (rtPCR) assay based on the cpa gene (cpa rtPCR) by using a bacterial strain panel composed of C. perfringens and non-C. perfringens Clostridium strains. All non-C. perfringens Clostridium strains tested negative, whereas all C. perfringens strains tested positive with the cpa rtPCR, for an analytical specificity and ubiquity of 100%. The cpa rtPCR assay was then used to confirm the identity of 116 putative C. perfringens isolates recovered after filtration of water samples and culture on mCP agar. Colonies presenting discordant results between the phenotype on mCP agar and cpa rtPCR were identified by sequencing the 16S rRNA and cpa genes. Four mCP(-)/rtPCR(+) colonies were identified as C. perfringens, whereas 3 mCP(+)/rtPCR(-) colonies were identified as non-C. perfringens. The cpa rtPCR was negative with all 51 non-C. perfringens strains and positive with 64 of 65 C. perfringens strains. Finally, we compared mCP agar and a CRENAME (concentration and recovery of microbial particles, extraction of nucleic acids, and molecular enrichment) procedure plus cpa rtPCR (CRENAME + cpa rtPCR) for their abilities to detect C. perfringens spores in drinking water. CRENAME + cpa rtPCR detected as few as one C. perfringens CFU per 100 ml of drinking water sample in less than 5 h, whereas mCP agar took at least 25 h to deliver results. CRENAME + cpa rtPCR also allows the simultaneous and sensitive detection of Escherichia coli and C. perfringens from the same potable water sample. In itself, it could be used to assess the public health risk posed by drinking water potentially contaminated with pathogens more resistant to disinfection.

Polythiophene biosensor for rapid detection of microbial particles in water.

Most microbial particles have a negatively charged surface and in this work, we describe a water quality monitoring application of a cationic polythiophene derivative (AH-35) for the rapid assessment of microbial contamination of water. Using E. coli as a prototype microbial particle, we demonstrate that the AH-35 polymer can provide a qualitative assessment of water if exposed to more than 500 CFU/mL, thereby paving the way to a new family of biosensors potentially useful for monitoring drinking water distribution systems.

Rapid detection of the Escherichia coli genospecies in water by conventional and real-time PCR.

The presence of Escherichia coli has long been established as the most reliable microbiological indication of fecal contamination in water. Current recommended culture-based methods for assessing water quality by the detection of E. coli are lengthy and lack ubiquity (ability to detect most if not all strains of a target microorganism). We describe rapid and sensitive conventional and real-time PCR assays specific to E. coli and Shigella, based on the nucleotide sequence of the highly conserved elongation factor Tu (tuf) gene enabling the detection of all members of the genospecies.

Comparative analysis of classical and molecular microbiology methods for the detection of Escherichia coli and Enterococcus spp. in well water.

The microbiological quality of 165 1 litre well water samples collected in the Québec City region was assessed by culture-based methods (mFC agar, Chromocult coliform agar, Colilert(®), MI agar, Chromocult enterococci, Enterolert™, and mEI agar) and by a molecular microbiology strategy, dubbed CRENAME-rtPCR, developed for the detection of Escherichia coli, Enterococcus spp., Enterococcus faecalis/faecium, and Bacillus atrophaeus subsp. globigii. In these drinking water samples, approved culture-based methods detected E. coli at rates varying from 1.8 to 3.6% and Enterococcus spp. at rates varying from 3.0 to 11.5%, while the molecular microbiology approach for E. coli was found to be as efficient, detecting contamination in 3.0% of samples. In contrast, CRENAME-rtPCR detected Enterococcus spp. in 27.9% of samples while the E. faecalis/faecium molecular assay did not uncover a single contaminated sample, thereby revealing a discrepancy in the coverage of waterborne enterococcal species detected by classical and molecular microbiology methods. The validation of the CRENAME-E. coli rtPCR test as a new tool to assess the quality of drinking water will require larger scale studies elaborated to demonstrate its equivalence to approved methods.

Infectious Disease Management through Point-of-Care Personalized Medicine Molecular Diagnostic Technologies.

Infectious disease management essentially consists in identifying the microbial cause(s) of an infection, initiating if necessary antimicrobial therapy against microbes, and controlling host reactions to infection. In clinical microbiology, the turnaround time of the diagnostic cycle (>24 hours) often leads to unnecessary suffering and deaths; approaches to relieve this burden include rapid diagnostic procedures and more efficient transmission or interpretation of molecular microbiology results. Although rapid nucleic acid-based diagnostic testing has demonstrated that it can impact on the transmission of hospital-acquired infections, we believe that such life-saving procedures should be performed closer to the patient, in dedicated 24/7 laboratories of healthcare institutions, or ideally at point of care. While personalized medicine generally aims at interrogating the genomic information of a patient, drug metabolism polymorphisms, for example, to guide drug choice and dosage, personalized medicine concepts are applicable in infectious diseases for the (rapid) identification of a disease-causing microbe and determination of its antimicrobial resistance profile, to guide an appropriate antimicrobial treatment for the proper management of the patient. The implementation of point-of-care testing for infectious diseases will require acceptance by medical authorities, new technological and communication platforms, as well as reimbursement practices such that time- and life-saving procedures become available to the largest number of patients.

Rapid concentration and molecular enrichment approach for sensitive detection of Escherichia coli and Shigella species in potable water samples.

In this work, we used a rapid, simple, and efficient concentration-and-recovery procedure combined with a DNA enrichment method (dubbed CRENAME [concentration and recovery of microbial particles, extraction of nucleic acids, and molecular enrichment]), that we coupled to an Escherichia coli/Shigella-specific real-time PCR (rtPCR) assay targeting the tuf gene, to sensitively detect E. coli/Shigella in water. This integrated method was compared to U.S. Environmental Protection Agency (EPA) culture-based Method 1604 on MI agar in terms of analytical specificity, ubiquity, detection limit, and rapidity. None of the 179 non-E. coli/Shigella strains tested was detected by both methods, with the exception of Escherichia fergusonii, which was detected by the CRENAME procedure combined with the E. coli/Shigella-specific rtPCR assay (CRENAME + E. coli rtPCR). DNA from all 90 E. coli/Shigella strains tested was amplified by the CRENAME + E. coli rtPCR, whereas the MI agar method had limited ubiquity and detected only 65 (72.2%) of the 90 strains tested. In less than 5 h, the CRENAME + E. coli rtPCR method detected 1.8 E. coli/Shigella CFU whereas the MI agar method detected 1.2 CFU/100 ml of water in 24 h (95% confidence). Consequently, the CRENAME method provides an easy and efficient approach to detect as little as one Gram-negative E. coli/Shigella cell present in a 100-ml potable water sample. Coupled with an E. coli/Shigella-specific rtPCR assay, the entire molecular procedure is comparable to U.S. EPA Method 1604 on MI agar in terms of analytical specificity and detection limit but provides significant advantages in terms of speed and ubiquity.

Ability of three DNA-based assays to identify presumptive Escherichia coli colonies isolated from water by the culture-based mFC agar method.

We tested the ability of three PCR assays, targeting uidA and tuf genes to correctly identify Escherichia coli colonies isolated from water and we compared them to two ß-glucuronidase-based culture methods (Colilert(®) and Readycult(®)), in terms of specificity and sensitivity. E. coli isolates recovered on mFC agar were first tested for the presence of the uidA positive colonies were presumed to be E. coli. For further characterization, uidA-negative colonies were subsequently identified using the Vitek 2 automated system. Colilert(®) and Readycult(®) detected 436 and 442 of 468 colonies identified as E. coli on mFC corresponding to sensitivities of 93.2 and 94.4%, respectively. None of the 59 non-E. coli isolates was detected by both methods for a specificity of 100%. Two (2) uidA and 1 tuf PCR assays were also tested. The uidA PCR assays yielded positive signals for 447 (95.5%) and 434 (92.7%) of 468 E. coli isolates tested respectively, whereas the tuf PCR assay showed a sensitivity of 100%. None of the 59 non-E. coli isolates was detected by both uidA PCR assays (100% specificity), whereas tuf PCR false-positive signals were obtained with Escherichia fergusonii and Escherichia albertii. However, since these 2 species are principally found in the feces of mammals and birds, their detection indicates a fecal contamination. Consequently, using a 1-h tuf rtPCR assay to confirm the identity of E. coli colonies on mFC agar is as specific, more sensitive, and potentially more cost-efficient than culture methods based on ß-glucuronidase detection.

Method for rapid and sensitive detection of Enterococcus sp. and Enterococcus faecalis/faecium cells in potable water samples.

We have developed a rapid and robust technological solution including a membrane filtration and dissolution method followed by a molecular enrichment and a real-time PCR assay, for detecting the presence of Enterococcus sp. or Enterococcus faecalis/faecium per 100 mL of water in less than 5 h and we compared it to Method 1600 on mEI agar in terms of specificity, sensitivity, and limit of detection. The mEI and the Enterococcus sp.-specific assay detected respectively 73 (64.0%) and 114 (100%) of the 114 enterococcal strains tested. None of the 150 non-enterococcal strains tested was detected by both methods with the exception of Tetragenococcus solitarius for the Enterococcus sp. assay. The multiplexed E. faecalis/faecium assay efficiently amplified DNA from 47 of 47 (100%) E. faecalis and 27 of 27 (100%) E. faecium strains tested respectively, whereas none of the 191 non-E. faecalis/faecium strains tested was detected. By simultaneously detecting the predominant fecal enterococcal species, the E. faecalis/faecium-specific assay allows a better distinction between enterococcal strains of fecal origin and those provided by the environment than Method 1600. Our procedure allows the detection of 4.5 enterococcal colony forming units (CFU) per 100 mL in less than 5 h, whereas the mEI method detected 2.3 CFU/100 mL in 24 h (95% confidence). Thus, our innovative and highly effective method provides a rapid and easy approach to concentrate very low numbers of enterococcal cells present in a 100 mL water sample and allows a better distinction between fecal and environmental enterococcal cells than Method 1600.

Analytical limits of three beta-glucosidase-based commercial culture methods used in environmental microbiology, to detect enterococci.

The enzyme-based test methods Enterolert, Chromocult Enterococci agar, and mEI agar, used to assess water quality through the detection Enterococcus spp., have been compared in terms of their analytical specificity and their ability to detect various enterococcal strains. To achieve this goal, we have tested 110 different non-enterococcal bacterial strains and 101 strains of Enterococcus spp. isolated from diverse origins. The results obtained showed that 69 (68.3%), 84 (83.2%), and 89 (88.1%) of the 101 enterococcal strains tested respectively yielded a positive signal with Enterolert, mEI, and Chromocult Enterococci. Regarding the specificity, none of the non-Enterococcus spp. strains tested were detectable by any of the three culture methods, except for Granulicatella adiacens which turned out positive on Chromocult Enterococci. The results of this study showed that, based on our collection of strains, the Enterolert test method detected less enterococcal strains than the two other methods.

Analytical comparison of nine PCR primer sets designed to detect the presence of Escherichia coli/Shigella in water samples.

The analytical performance of 9 different PCR primer sets designed to detect Escherichia coli and Shigella in water has been evaluated in terms of ubiquity, specificity, and analytical detection limit. Of the 9 PCR primer sets tested, only 3 of the 5 primer sets targeting uidA gene and the primer set targeting tuf gene amplified DNA from all E. coli strains tested. However, of those 4 primer sets, only the primer set targeting the tuf gene also amplified DNA from all Shigella strains tested. For the specificity, only the primer sets targeting the uidA gene were 100% specific although the primer sets targeting 16S rRNA, phoE, and tuf genes only amplified Escherichia fergusonii as non-specific target. Finally, the primer set targeting the 16S-ITS-23S gene region, was not specific as it amplified DNA from many other Enterobacteriaceae species. In summary, only the assay targeting the tuf gene detected all E. coli/Shigella strains tested in this study. However, if it becomes important to discriminate between E. coli and E. fergusonii, assays targeting the uidA gene would represent a good choice although none of them were totally ubiquitous to detect of the presence of Shigella strains.

Analytical limits of four beta-glucuronidase and beta-galactosidase-based commercial culture methods used to detect Escherichia coli and total coliforms.

Colilert (Colilert), Readycult Coliforms 100 (Readycult), Chromocult Coliform agar ES (Chromocult), and MI agar (MI) are beta-galactosidase and beta-glucuronidase-based commercial culture methods used to assess water quality. Their analytical performance, in terms of their respective ability to detect different strains of Escherichia coli and total coliforms, had never been systematically compared with pure cultures. Here, their ability to detect beta-glucuronidase production from E. coli isolates was evaluated by using 74 E. coli strains of different geographic origins and serotypes encountered in fecal and environmental settings. Their ability to detect beta-galactosidase production was studied by testing the 74 E. coli strains as well as 33 reference and environmental non-E. coli total coliform strains. Chromocult, MI, Readycult, and Colilert detected beta-glucuronidase production from respectively 79.9, 79.9, 81.1, and 51.4% of the 74 E. coli strains tested. These 4 methods detected beta-galactosidase production from respectively 85.1, 73.8, 84.1, and 84.1% of the total coliform strains tested. The results of the present study suggest that Colilert is the weakest method tested to detect beta-glucuronidase production and MI the weakest to detect beta-galactosidase production. Furthermore, the high level of false-negative results for E. coli recognition obtained by all four methods suggests that they may not be appropriate for identification of presumptive E. coli strains.

Information content of data measured with a multiple-field-of-view lidar.

Lidars with multiple fields of view (MFOVs) are promising tools for gaining information on cloud particle size. We perform a study of the information content of MFOV lidar data with the use of eigenvalue analysis. The approach we have developed permits an understanding of the main features of MFOV lidars and provides a way to relate the accuracy of particle size estimation with the measurement uncertainty and the scattering geometry such as the cloud-base height and the lidar sounding depth. Second-order scattering computations are performed for an extended range of particle sizes and for a wide range of lidar fields of view (FOVs). The results obtained allow us to specify the areas of possible applications of these lidars in cloud studies. Comparison of results obtained with polarized and cross-polarized scattered components demonstrate that the cross-polarized signal should provide a more stable retrieval and is preferable when double scattering is highly dominant. Our analysis allows for the estimation of the optimal number of FOVs in the system and their angular distribution, so this work can be a useful tool for practical MFOV lidar design.

Simple relation between lidar multiple scattering and depolarization for water clouds.

An empirical relationship is derived between the multiple-scattering fraction and the linear depolarization ratio by using Monte Carlo simulations of water clouds measured by backscatter lidar. This relationship is shown to hold for clouds having a wide range of extinction coefficients, mean droplet sizes, and droplet size distribution widths. The relationship is also shown to persist for various instrument fields of view and for measurements made within broken cloud fields. The results obtained from the Monte Carlo simulations are verified by using multiple-field-of-view lidar measurements. For space-based lidars equipped to measure linear depolarization ratios, this new relationship can be used to accurately assess signal perturbations due to multiple scattering within nonprecipitating water clouds.