Maternal and Paternal Household Pesticide Exposure During Pregnancy and Risk of Childhood Acute Lymphoblastic Leukemia

OBJECTIVE

The aim of this study was to investigate whether risk estimates for childhood acute lymphoblastic leukemia change when restricting model comparison groups to "nonpesticide exposure" (NPE10) households.

METHODS

Cases ( n = 1810) 15 years or younger were identified through Children's Cancer Group institutions between 1989 and 1993 and age-/sex-matched to controls ( n = 1951). Household pesticide use during pregnancy/month prior was collected via telephone. NPE10 comparison group reporting no parental exposure to 10 pesticide classes was identified.

RESULTS

Adjusted odds ratios increased from 15% to 49% when limiting the comparison to NPE10. Maternal termite insecticide exposure was associated with greatest risk (adjusted odds ratio, 4.21; 95% confidence interval, 2.00-8.88). There was minimal evidence of interaction by child sex or occupational pesticide exposure, and no monotonic dose-response pattern with frequency of use (times per year).

CONCLUSIONS

Elevated risks are consistent with published pooled-/meta-analyses and DNA damage. The consistency and magnitude of these associations warrant product labeling, exposure reduction interventions, or both.

Theory of coupled resistive drift and resistive drift ballooning instabilities in fusion plasma

Drift wave instabilities (DWI) associated with the two-fluid dynamics seems to be responsible for anomalous transport in modern day tokamaks. Ballooning instabilities tend to exchange flux tubes of different pressure, resulting in convective transport. The micro-level turbulence (drift wave) is coupled with the macro-level (ballooning mode) dynamics in fusion experiments. The co-existence of DWI and drift ballooning instabilities (DBI) is discussed in this work using a four-field plasma model. The formulation preserves both the microscopic and macroscopic dynamics of plasma. To demonstrate the coupling, a new dispersion relation is derived to analyze stability of the coupled modes in a non-uniform magnetized plasma. Linear stability of coupled drift-ballooning and drift-acoustic modes have been explored. The two-fluid effect (micro-level influence) through diamagnetic drift frequency for electrons and curvature drift frequency on unstable modes are demonstrated.

CFD-based process optimization of a dissolved air flotation system for drinking water production

Dissolved air flotation (DAF) has received more attention recently as a separation technique in both drinking water as well as wastewater treatment. However, the process as well as the preceding flocculation step is complex and not completely understood. Given the multiphase nature of the process, fluid dynamics studies are important to understand and optimize the DAF system in terms of operation and design. The present study is intended towards a comprehensive computational analysis for design optimization of the treatment plant in Kluizen, Belgium. Setting up the modelling framework involving the multiphase flow problem is briefly discussed. 3D numerical simulations on a scaled down model of the DAF design were analysed. The flow features give better confidence, but the flocs escape through the outlet still prevails which is averse to the system performance. In order to improve the performance and ease of maintenance, design modifications have been proposed by using a perforated tube for water extraction and are found to be satisfactory. The discussion is further reinforced through validating the numerical model against the experimental findings for stratified flow conditions.

Water and wastewater CFD and validation: are we losing the balance?

A literature screening on computational fluid dynamics (CFD) modelling in water treatment applications showed a vast range of validation ranging from no validation at all, over residence time distribution (RTD) and tracer testing, to velocity field, species concentration and, finally, turbulence properties measurements. The validation level also differs depending on process scale (laboratory, pilot, full) and type of system (rheology, single phase vs. multiphase). Given the fact that CFD is in more widespread use, a discussion on the extent and need of validation needs to be initiated. This paper serves as a discussion starter on the topic.

Resistive drift instabilities for thermal and non-thermal electron distributions in electron-ion plasma

Local dispersion relations for resistive drift mode in a nonuniform magnetize plasma are derived for thermal and non-thermal distribution of electrons. The coupled mode equations are obtained by using Braginskii's transport equations for ions and electrons with thermal as well as non-thermal (Cairns and kappa) distribution for electrons. The dispersion relations are then analyzed both analytically as well as numerically for all distributions. It is found that growth rate is highest for Maxwellian, Intermediate for kappa and lowest for Cairns distribution. It has been found that increasing values of Γ (which estimate population of non-thermal electrons) for Cairn distributed electrons are able to stabilize the mode. Furthermore, increasing the values of κ (which is spectral index) for the kappa distributed electrons have destabilizing effects on the mode. The result might be useful in the interpretation of electromagnetic fluctuations in nonuniform magneto-plasma in which resistivity is a key element in calculation of drift instabilities in the presence of thermal or nonthermal electron distributions, such systems are extensively observed in laboratory as well as space plasma.

Effect of sensor location on controller performance in a wastewater treatment plant

Complete mixing is hard to achieve in large bioreactors in wastewater treatment plants. This often leads to a non-uniform distribution of components such as dissolved oxygen and, hence, the process rates depend on them. Furthermore, when these components are used as input for a controller, the location of the sensor can potentially affect the control action. In this contribution, the effect of sensor location and the choice of setpoint on the controller performance were examined for a non-homogeneously mixed pilot bioreactor described by a compartmental model. The impacts on effluent quality and aeration cost were evaluated. It was shown that a dissolved oxygen controller with a fixed setpoint performs differently as a function of the location of the sensor. When placed in a poorly mixed location, the controller increases the aeration intensity to its maximum capacity leading to higher aeration costs. When placed just above the aerated zone, the controller decreases the aeration rate resulting in lower dissolved oxygen concentrations in the remainder of the system, compromising effluent quality. In addition to the location of the sensor, the selection of an appropriate setpoint also impacts controller behavior. This suggests that mixing behavior of bioreactors should be better quantified for proper sensor location and controller design.

Testing the Holtzworth-Munroe and Stuart (1994) batterer typology

A. Holtzworth-Munroe and G. L. Stuart (1994) proposed that 3 subtypes (family only [FO], borderline-dysphoric [BD], and generally violent-antisocial [GVA]) would be identified using 3 descriptive dimensions (i.e., severity of marital violence, generality of violence, psychopathology) and would differ on distal and proximal correlates of violence. Maritally violent men (n = 102) and their wives were recruited from the community, as were 2 comparison groups of nonviolent couples (i.e., maritally distressed and nondistressed). Four clusters of violent men were identified. Three resembled the predicted subtypes and generally differed in the manner predicted (e.g., FO men resembled nonviolent groups: BD men scored highest on measures of dependency and jealousy; GVA men had the most involvement with delinquent peers, substance abuse, and criminal behavior; and both BD and GVA men were impulsive, accepted violence, were hostile toward women, and lacked social skills). The 4th cluster (i.e., low-level antisocial) fell between the FO and GVA clusters on many measures.

Testing the Holtzworth-Munroe and Stuart (1994) batterer typology

A. Holtzworth-Munroe and G. L. Stuart (1994) proposed that 3 subtypes (family only [FO], borderline-dysphoric [BD], and generally violent-antisocial [GVA]) would be identified using 3 descriptive dimensions (i.e., severity of marital violence, generality of violence, psychopathology) and would differ on distal and proximal correlates of violence. Maritally violent men (n = 102) and their wives were recruited from the community, as were 2 comparison groups of nonviolent couples (i.e., maritally distressed and nondistressed). Four clusters of violent men were identified. Three resembled the predicted subtypes and generally differed in the manner predicted (e.g., FO men resembled nonviolent groups: BD men scored highest on measures of dependency and jealousy; GVA men had the most involvement with delinquent peers, substance abuse, and criminal behavior; and both BD and GVA men were impulsive, accepted violence, were hostile toward women, and lacked social skills). The 4th cluster (i.e., low-level antisocial) fell between the FO and GVA clusters on many measures.