Atmospheric dispersion and transmission of Legionella from wastewater treatment plants: A 6-year case-control study.

Legionnaires Disease incidence has risen in the Netherlands in recent years. For the majority of the cases, the source of infection is never identified. Two Dutch wastewater treatment plants (WWTPs) have previously been identified as source of outbreaks of Legionnaires Disease (LD) among local residents. The objective of this study is to examine if LD patients in the Netherlands are more exposed to aerosols originating from WWTPs than controls. METHODS: An atmospheric dispersion model was used to generate nationwide exposure maps of aerosols from 776 WWTPs in the Netherlands. Municipal sewage treatment plants and industrial WWTPs were both included. Exposure of LD cases and controls at the residential address was compared, in a matched case-control design using a conditional logistic regression. Cases were notified LD cases with onset of disease in the period 2013-2018 in the Netherlands (n = 1604). RESULTS: Aerosols dispersed over a large part of the Netherlands, but modelled concentrations are estimated to be elevated in close proximity to WWTPs. A statistically significant association was found between LD and the calculated annual average aerosol concentrations originating from WWTPs (odds-ratio: 1.32 (1.06-1.63)). This association remained significant when the two outbreak-related WWTPs were removed from the analysis (odds-ratio: 1.28 (1.03-1.58)). CONCLUSION: LD cases were more exposed to aerosols from WWTPs than controls. This indicates that exposure to aerosols dispersed from WWTPs caused Legionnaires Disease in residents living near WWTPs in the period 2013-2018. In order to investigate which characteristics of WWTPs are associated with an increased LD risk, the WWTP database should be updated and more data is needed on the presence and survival of aerosolized Legionella bacteria to improve the Legionella dispersion modelling. Furthermore, it is recommended to further investigate how aerosol dispersion of WWTPs can effectively be reduced in order to reduce the potential health risk.

Human Q fever incidence is associated to spatiotemporal environmental conditions.

Airborne pathogenic transmission from sources to humans is characterised by atmospheric dispersion and influence of environmental conditions on deposition and reaerosolisation. We applied a One Health approach using human, veterinary and environmental data regarding the 2009 epidemic in The Netherlands, and investigated whether observed human Q fever incidence rates were correlated to environmental risk factors. We identified 158 putative sources (dairy goat and sheep farms) and included 2339 human cases. We performed a high-resolution (1 × 1 km) zero-inflated regression analysis to predict incidence rates by Coxiella burnetii concentration (using an atmospheric dispersion model and meteorological data), and environmental factors - including vegetation density, soil moisture, soil erosion sensitivity, and land use data - at a yearly and monthly time-resolution. With respect to the annual data, airborne concentration was the most important predictor variable (positively correlated to incidence rate), followed by vegetation density (negatively). The other variables were also important, but to a less extent. High erosion sensitive soils and the land-use fractions "city" and "forest" were positively correlated. Soil moisture and land-use "open nature" were negatively associated. The geographical prediction map identified the largest Q fever outbreak areas. The hazard map identified highest hazards in a livestock dense area. We conclude that environmental conditions are correlated to human Q fever incidence rate. Similar research with data from other outbreaks would be needed to more firmly establish our findings. This could lead to better estimations of the public health risk of a C. burnetii outbreak, and to more detailed and accurate hazard maps that could be used for spatial planning of livestock operations.

High HIV prevalence among children presenting for general consultation in rural Cameroon.

Data on the HIV-prevalence children presenting to health care facilities in sub-Saharan Africa are scant in general, and the debate about opportunities for paediatric HIV screening is ongoing. Nine hundred and eighty-one children with unknown HIV-status presenting to a large general paediatric outpatient department in rural Cameroon were tested using the Determine HIV-1/2 rapid test (Abbott), and positive results were confirmed with the Hexagon HIV rapid test (Human Diagnostics). In children younger than 18 months, HIV infection was confirmed by PCR testing. Median age was 1.3 years and 52.8% were of male gender. In 514 children below 18 months of age, 16 (3.1%) tested positive. Of those, HIV-1 PCR was available for 11 children, of whom 6 had a positive PCR result. HIV prevalence was highest in the age group 5-9 years, being 8.8%. Malnutrition (33.3 vs 5.2%, p < 0.001) was associated with HIV infection. Our study results indicate that HIV testing should be offered to all children at possible entry points to medical care, irrespective of symptoms, in order to reduce HIV-associated mortality through timely initiation of antiretroviral therapy.

A wireless 64-channel ECoG recording electronic for implantable monitoring and BCI applications: WIMAGINE.

A wireless, low power, 64-channel data acquisition system named WIMAGINE has been designed for ElectroCorticoGram (ECoG) recording. This system is based on a custom integrated circuit (ASIC) for amplification and digitization on 64 channels. It allows the RF transmission (in the MICS band) of 32 ECoG recording channels (among 64 channels available) sampled at 1 kHz per channel with a 12-bit resolution. The device is powered wirelessly through an inductive link at 13.56 MHz able to provide 100mW (30mA at 3.3V). This integration is a first step towards an implantable device for brain activity monitoring and Brain-Computer Interface (BCI) applications. The main features of the WIMAGINE platform and its architecture will be presented, as well as its performances and in vivo studies.

Studies in organic archaeometry VII--differentiation of wood and bark pitches by pyrolysis capillary gas chromatography (PY-CGC).

Tars and pitches were prepared from wood and bark of various deciduous trees and conifers and analysed with the intention to distinguish between various starting materials. All this was done before the background of an archaeometrical problem: to provide a basis for the chemical identification of those pitches which are frequently found in archaeological excavations. Intending to extend the already existing possibilities for such analyses the present paper is dealing with the application of pyrolysis coupled with capillary gas chromatography and by subsequent chemometric studies. It could be shown that by this technique indeed not only tars and pitches prepared from deciduous trees and from conifers could clearly be differentiated, but that even respective species could be identified. Thus a fundament is provided for future studies aiming to identify the starting material of real archaeological finds by a novel method which requires by far less quantities of sample material as compared to the methods hitherto used by us.

Formation and stability of a suspended biomimetic lipid bilayer on silicon submicrometer-sized pores.

We report the fabrication of a thin silicon membrane with an array of micrometer and submicrometer pores that acts as a scaffold for suspending a lipid bilayer. We successfully deposited a lipid bilayer by the Langmuir-Blodgett method on a synthetic silicon membrane bearing arrays of pores with sizes of 1000, 650, and 300 nm. Topographic images obtained by AFM showed a suspended lipid film spanning the pores, whatever the pore size. Higher stability of bilayers supported on smaller pores was shown by AFM characterization. These results represent an important first step to creating a biomimetic environment to study cell membrane dynamics and/or in developing a biosensor.

Surgical therapy for Parkinson's disease.

High frequency stimulation (HFS) has become the main alternative to medical treatment, due to its reversibility, adaptability, and low morbidity. Initiated in the thalamus (Vim) for the control of tremor, HFS has been applied to the Pallidum (GPi), and then to the subthalamic nucleus (STN), suggested by experiments in MPTP monkeys. STN-HFS is highly efficient on tremor, rigidity and bradykinesia and is now widely applied. Criteria for success are correct patient selection and precise electrode placement. The best outcome predictor is the response to Levodopa. The mechanisms of action might associate inhibition of cell firing, jamming of neuronal message and exhaustion of synaptic neurotransmitter release. The inhibition of glutamate STN release could be neuroprotective on nigral cells. Animal experiments support this hypothesis, not contradicted by the long-term follow up of patients. Neuroprotection might have considerable impact on the management of PD patient and warrants clinical trials.

Modest evidence for linkage and possible confirmation of association between NOTCH4 and schizophrenia in a large Veterans Affairs Cooperative Study sample.

Wei and Hemmings [2000: Nat Genet 25:376-377], using 80 British parent-offspring trios, identified a number of NOTCH4 variants and haplotypes that showed statistically significant evidence of association to schizophrenia. Specifically, the 10 repeat allele of a (CTG)(n) marker and the 8 repeat allele of a (TAA)(n) marker demonstrated excess transmission to affected individuals; SNP21 and haplotypes SNP2-(CTG)(n) and SNP12-SNP2-(CTG)(n) also showed significant associations. In an attempt to replicate these findings, we tested for linkage and association between the same five markers used by Wei and Hemmings in 166 families collected from a multi-center study conducted by the Department of Veterans Affairs (DVA) Cooperative Study Program (CSP). The families include 392 affected subjects (schizophrenia or schizoaffective disorder, depressed) and 216 affected sibling pairs. The families represent a mix of European Americans (n = 62, 37%), African Americans (n = 60, 36%), and racially mixed or other races (n = 44, 27%). We identified moderate evidence for linkage in the pooled race sample (LOD = 1.25) and found excess transmission of the 8 (P = 0.06) and 13 (P = 0.04) repeat alleles of the (TAA)(n) marker to African American schizophrenic subjects. The 8 and 13 repeat alleles were previously identified to be positively associated with schizophrenia by Wei and Hemmings [2000: Nat Genet 25:376-377] and Sklar et al. [2001: Nat Genet 28:126-128], respectively.

Examination of genetic linkage of chromosome 15 to schizophrenia in a large Veterans Affairs Cooperative Study sample.

Previous studies have reported genetic linkage evidence for a schizophrenia gene on chromosome 15q. Here, chromosome 15 was examined by genetic linkage analysis using 166 schizophrenia families, each with two or more affected subjects. The families, assembled from multiple centers by the Department of Veterans Affairs Cooperative Study Program, consisted of 392 sampled affected subjects and 216 affected sibling pairs. By DSM-III-R criteria, 360 subjects (91.8%) had a diagnosis of schizophrenia and 32 (8.2%) were classified as schizo-affective disorder, depressed. Participating families had diverse ethnic backgrounds. The largest single group were northern European American families (n = 62, 37%), but a substantial proportion was African American kindreds (n = 60, 36%). The chromosome 15 markers tested were spaced at intervals of approximately 10 cM over the entire chromosome and 2-5 cM for the region surrounding the alpha-7 nicotinic cholinergic receptor subunit gene (CHRNA7). These markers were genotyped and the data analyzed using semiparametric affecteds-only linkage analysis. In the European American families, there was a maximum Z-score of 1.65 between markers D15S165 and D15S1010. These markers are within 1 cM from CHRNA-7, the site previously implicated in schizophrenia. However, there was no evidence for linkage to this region in the African America kindreds.

Desplazamientos : Consideración prioritaria en el diseño sismorresistente de puentes

Mecanismos de apoyo inadecuados, la falta de dispositivos para la restricción de desplazamientos horizontales y la ausencia de continuidad de la superestructura, han mostrado ser la causa principal del colapso de numerosos puentes durante sismos destructivos recientes. Estructuras viales diseñadas para una demanda sísmica alta, han fallado debido a la mala cocepción del sistema resistente a fuerzas laterales y debido a la falla de los mecanismos de soporte, aún cuando la supestructura no sufrió daño. La experiencia a demostrado que el diseño sísmico de puentes puede estar influenciado por los desplazamientos de la superestructura y no por la resistencia de las pilas y columnas que forman parte de la superestructura (AU)

Philosophy and techniques of seismic retrofitting

The author presents the concept of seismic rehabilitation of buildings, from the perspective of a small developing country. The adopted solutions correspond to the common construction practice in the country but the expressed philosophy and criteria can be applied to other regions in the world. Costa Rica is characterized by a long tradition of seismic reinforcement of buildings, public and private. This has resulted in good structural behavior as shown during the intense seismic activity that affected the country between March 1990 and April 1991. The policy adopted by the Costa Rican government and other public institutions and the positive attitude shown by building owners, aware of the seismic hazard and the need to prevent economic losses, have resulted in an intense activity in the field of seismic rehabilitation of buildings. Different procedures and systems of structural strengthening and seismic rehabilitation are presented. Rules for structural configuration and strengthening are commented, as well as constructive details for jacketing of elements, connections, anchorage and continuity of reinforcement. The use of structual walls as an efficient way to add strength and, at the same time, control the flexibility of the existing system, in order to reduce lateral displacements and reduce nonstructural damage, is emphasized. Examples of seismic rehabilitation of buildings and their behavior during the three earthquakes that affected Costa Rica are presented (AU)

Aspectos conceptuales del diseño sismorresistente

La experiencia demuestra que la aplicación de los códigos sísmicos no garantiza necesariamente el buen comportamiento de las edificaciones. La falla de estructuras diseñadas de acuerdo con los códigos confirma que aún no podemos cuantificar adecuadamente las características del movimiento de terreno y que las solicitaciones sísmicas pueden ser mayores que las deducidas de los espectros de diseño. El diseñador otorga frecuentemente excesiva confianza a los resultados del análisis dinámico y del cálculo electrónico, olvidando que nuestra habilidad para analizar las estructuras excede en mucho nuestra capacidad para predecir la demanda sísmica. El diseño sismorresistente en una diciplina aún llena de incertidumbre, que demanda del ingeniero capacidad para intuir el comportamiento de las estructuras , criterio para seleccionar el sistema resistente más eficiente y pericia para satisfacer requerimientos arquitectónicos y estructurales. El trabajo en equipo y un estrecha colaboración entre arquitecto y diseñador estructural son requisitos para el exito del proyecto (AU)

Refuerzo sísmico de estructuras

El refuerzo sísmico de una estructura puede ser necesariocuando la obra ha sufrido daños a causa de un terremoto o si se determina que un edificio es vulnerable a sufrir daños severos o colapso. Obras esenciales deben seguir prestando servicios después de una catástrofe, por lo tanto, deben resistir sismos destructivos sin sufrir daños secundarios significativos que puedan poner en peligro su funcionamiento; un estudio de vulnerabilidad sísmica puede concluir en la necesidad de refuerzo estructural. Se describen los diferentes métodos para el refuerzo de edificios, tendientes a mejorar su comportamiento sísmico y se resalta la bondad de los muros estructurales como elementos de refuerzo, pues introducen mayor rigidez, reducen los desplazamientos laterales y la cuantía de los daños. Se comentan las reglas de estructuración, se dan ejemplos de refuerzo sísmico de edificios y se presentan detalles de anclajes, conexiones y continuidad del refuerzo.(AU)

Interacción mampostería - estructura

Paredes de mampostería integradas a la estructura cambian significativamente las propiedades dinámicas y el comportamiento sísmico de los edificios, restringen la libre deformación del sistema resistente y modifican la distribución de masas y rigideces. Se comentan los diferentes efectos que produce la interacción de la mampostería con la estructura sometida a solicitaciones sísmicas, y que pueden conducir a la falla de elementos estructurales y al colapso del edificio. Se hace énfasis en la necesidad de considerar en el análisis y diseño dicha interacción; en su defecto, se deben adoptar medidas constructivas para desligar las paredes y tabiques del sistema resistente, para lo cual se presentan soluciones apropiadas.(AU)