The Vision of Toxicity Testing in the 21st Century: Moving from Discussion to Action

Over the past year, a series on commentaries have appeared in the Toxicological Sciences Forum Series related to the 2007 National Research Council (NRC) publication, Toxicity Testing in the 21st Century: A Vision and A Strategy. The first article in the series provided an overview of the vision and was accompanied by an editorial by the three editors of Toxicological Sciences. During the past year, eight invited commentaries from the academic, industrial, and regulatory sectors have provided diverse perspectives on the vision, noted challenges to its implementation, and highlighted aspects of toxicity testing that were not addressed in the original NRC report. Here, we offer a summary of the main points raised by the commentators in tabular form, identify a number of common themes, and finish the series by providing our perspective on several key issues in charting the path forward to move from discussion to action

Systematic Design of Multiport Antennas for MIMO-enabled Mobile Wireless Terminals

Mobile wireless communication systems have undergone a tremendous development in the past decade. One of the major advancements is the widespread use of MIMO transmission schemes beginning with the introduction of the 3rd Generation Partnership Project (3GPP) standard LTE and being extended in LTE Advanced. So as to support MIMO transmission schemes mobile terminals must be equipped with multiport antenna systems. The term refers to an arrangement of two or more antenna elements operating in the same frequency range and mounted on the same mobile wireless platform. Reduced volume per antenna element and strong interaction between all antenna elements are major design challenges and require for new systematic design approaches beyond classical single antenna design. The ongoing miniaturization of mobile terminals, the extension of the mobile spectrum and in particular the opening of new mobile communication bands at the lower end of the spectrum exacerbate these challenges. Design and characterization of multiport antennas have therefore become subject of high interest and of numerous research projects in both academia and industry. This dissertation contributes to the development of systematic design procedures for multiport antennas with emphasis on accounting for the restrictions and side conditions which apply when designing multiport antennas for actual consumer equipment. The dissertation has developed along an industry funded research project, with a focus on electrically small devices where antenna design is constantly faced with fundamental physical limits. Chapter 1 gives an overview of the state of the art in antenna characterization and design techniques applicable to multiport antennas for MIMO. Chapter 2 introduces into the analysis of multiport antennas in terms of their radiation modes. Modal analysis, based on spectrum of the radiation matrix, allows for unambiguous characterization of a multiport antenna by means of invariant properties. Modal descriptive quantities are defined which are basic to the design approach followed in this dissertation. Analyzing a multiport antenna with respect to its radiation modes is possible only after a design concept has been conceived. More fundamental from a design point of view is the question for the space of feasible radiation modes and their realization under the constraint of a given chassis form factor. Chapter 3 addresses this question based on the theory of characteristic modes for conducting bodies. The relevant properties of characteristic modes on the chassis of mobile terminals are reviewed. The excitation of characteristic modes by means of capacitive and inductive coupling elements is investigated in detail. Finally, a systematic design approach for multiport antennas is presented in which the antenna’s radiation modes are constructively derived from the usable characteristic chassis modes. Chapter 4 deals with design of matching networks for N-port antennas. Starting from the general expression for the scattering matrix of an ideal 2N-port matching network different topologies and alternative implementations are discussed. As a solution of particular interest in cases where some radiation modes feature insufficient bandwidths, special attention is given to systematic design of MDN which maps radiation modes to external ports of the antenna system. Chapter 5 focuses on the particular problems encountered in the design of antenna systems for extremely small mobile wireless terminals. After a review of applicable fundamental limits bandwidth estimation and approaches to maintain a decent total efficiency are discussed. The combination of electrical switching in the antenna structure with electrical tuning in an external matching network is suggested in this context. The DL-MIMO concept is introduced as a system level measure to cope with insufficient bandwidth. The different aspects are exemplified with the design of a 2-port MIMO antenna for a USB dongle. Chapter 6 describes in detail design, fabrication and measurement of four antenna prototypes. The validity of the design approach described in the previous chapters is confirmed. In conclusion, a systematic design approach, which combines the theory of characteristic chassis modes for conducting bodies with modal analysis of a multiport antenna, i.e. considers the spectrum of its radiation matrix is presented. The approach is successfully applied to a number of practically relevant design problems. The design technique permits identification of near optimum antenna solutions which approach the fundamental limits of attainable bandwidth and total efficiency.Systematischen Entwurf von Multiport-Antennen für MIMO-fähigen Mobilfunkendgeräte Die Mobilkommunikation hat in den letzten Jahren eine enorme Entwicklung durchlaufen. Eine der wesentlichen technischen Weiterentwicklungen ist der Übergang zu MIMO Übertragungsverfahren, in großem Maßstab beginnend mit der Einführung des 3GPP Standards LTE und in grÖßerem Umfang noch im zukünftigen LTE-Advanced. Mobile Endgeräte müssen dazu mit Mehrtorantennen ausgestattet sein. Der Begriff Mehrtorantenne bezeichnet eine Anordnung von zwei oder mehr Antennenelementen, die im gleichen Fequenzbereich betrieben werden und auf einer gemeinsamen Plattform angeordnet sind. Die Verringerung des je Antennenelement zur Verfügung stehenden Volumens und die starke Kopplung zwischen den Antennenelementen führen auf neue Herausforderungen für den Entwurf. Neue, systematische Entwurfsmethoden jenseits der klassischen Methoden für den Entwurf von Einzelantennen sind gefordert. Die fortschreitende Miniaturisierung mobiler Endgeräte, die Erweiterung des für den Mobilfunk genutzten Spektrums und insbesondere die Öffnung neuer Bander am unteren Ende des Spektrums für den Mobilfunk verschärfen die Anforderung an die Entwurfsmethodik. Entwurf und Charakterisierung von Mehrtorantennen sind deswegen heute Themen von großem Interesse und Gegenstand zahlreicher industrieller und akademischer Forschungsprojekte. Die vorliegende Dissertation liefert einen Beitrag zur Entwicklung systematischer Entwurfsverfahren für Mehrtorantennen unter besonderer Berücksichtigung der Einschränkungen und Randbedingungen die beim Entwurf von kommerziellen Endgeräten vorliegen. Zahlreiche Fragestellungen ergaben sich aus einem vom Verfasser bearbeiteten industriellen Forschungs- und Entwicklungsprojekt mit Schwerpunkt auf elektrisch kleinen Endgeräten, bei denen der Entwurf stets mit fundamentalen physikalischen Schranken konfrontiert ist. Kapitel 1 gibt einen Überblick über den Stand der Technik auf dem Gebiet des Entwurfs und der Charakterisierung von Mehrtorantennen für MIMO Anwendungen. Kapitel 2 führt in die Analyse von Mehrtorantennen mit Hilfe ihrer Strahlungsmoden ein. Die modale Betrachtung auf Grundlage des Spektrums der Strahlungsmatrix gestattet es, Mehtorantennen mit Hilfe ihrer invarianten Eigenschaften eindeutig zu charakterisieren. Es werden die modalen Beschreibungsgrössen definiert auf denen der in dieser Arbeit verfolgte Entwurfsansatz basiert. Die Strahlungsmoden einer Mehtorantenne können jedoch erst betrachtet werden, wenn ein Entwurf bereits vorliegt. Die vom Standpunkt der Entwurfsmethodik wichtigere Frage ist die nach Raum der unter den Einschränkungen eines gegebenen Geräte-Formfaktors realisierbaren Strahlungsmoden. Sie wird in Kapitel 3 auf Grundlage der Theorie Charakteristischer Moden leitender Körper behandelt. Die relevanten Eigenschaften charakteristischer Moden auf dem Gehäuse elektrisch kleiner mobiler Endgeräte werden betrachtet. Die Anregung charakteristischer Moden mit Hilfe von kapazitiven und induktiven Koppelelementen wird ausführlich untersucht. Abschließend wird ein Entwurfsansatz für Mehtorantennen beschrieben, in welchem die Strahlungsmoden der Antenne konstruktiv aus den nutzbaren charakteristischen Moden des Gehäuses abgeleitet werden. In Kapitel 4 werden Anpassnetzwerke für N-Tor Antennen behandelt. Ausgehend von der allgemeinen Formulierung für die Streumatrix des benötigten 2N-Tor Netzwerkes werden verschiedene Topologien und Realisierungsalternativen diskutiert. Gesondert betrachtet werden noch einmal MDNs, welche die Strahlungsmoden einer Mehtorantenne unmittelbar auf die Speisetore abbilden, da sie in Falle unzureichender modaler Bandbreiten, von besonderem Interesse sind. Kapitel 5 fokussiert auf die besonderen Probleme bei beim Entwurf extrem kleiner Antennensysteme. Nach Betrachtung in die maßgeblichen physikalischen Beschränkungen werden die Abschätzung erreichbarer Bandbreiten und Maßnahmen zur Sicherstellung eines akzeptablen Wirkungsgrades diskutiert. Vorgeschlagen wird in diesem Zusammenhang die Kombination von elektrisch rekonfigurierbaren Antennenstrukturen mit elektrisch abstimmbaren Anpass-Netzwerken. Die verschiedenen Aspekte werden am Beispiel des Entwurfs eines 2-Tor MIMO Antennensystems für einen USB Dongle erläutert. pKapitel 6 beschreibt im Detail den Entwurf, die Herstellung und die messtechnische Charakterisierung vier unterschiedlicher Prototypen von Mehrtorantennen. Anhand der Beispiele wird der in den vorherigen Kapiteln entwickelte Entwurfsansatz validiert. Insgesamt wird mit dieser Arbeit ein systematischer Entwurfsansatz vorgeschlagen, der auf der Kombination der Theorie charakteristische Moden leitender Körper mit der modalen Analyse von Mehrtorantennen, d.h. der Betrachtung des Spektrums der Strahlungsmatrix aufbaut. Der Ansatz wird erfolgreich auf eine Reihe praktisch relevanter Entwurfsaufgaben angewandt. Er führt auf ein systematisches Entwurfsverfahren, das es gestattet, Lösungen in der Nähe der physikalischen Grenzen für die erreichbare Bandbreite und den Wirkungsgrad aufzufinden

Ambient Air Pollution and Cancer Mortality in the Cancer Prevention Study II

BACKGROUND: The International Agency for Research on Cancer classified both outdoor air pollution and airborne particulate matter as carcinogenic to humans (Group 1) for lung cancer. There may be associations with cancer at other sites; however, the epidemiological evidence is limited. OBJECTIVE: The aim of this study was to clarify whether ambient air pollution is associated with specific types of cancer other than lung cancer by examining associations of ambient air pollution with nonlung cancer death in the Cancer Prevention Study II (CPS-II). METHODS: Analysis included 623,048 CPS-II participants who were followed for 22 y (1982-2004). Modeled estimates of particulate matter with aerodynamic diameter <2.5microm (PM2.5) (1999-2004), nitrogen dioxide (NO2) (2006), and ozone (O3) (2002-2004) concentrations were linked to the participant residence at enrollment. Cox proportional hazards models were used to estimate associations per each fifth percentile-mean increment with cancer mortality at 29 anatomic sites, adjusted for individual and ecological covariates. RESULTS: We observed 43,320 nonlung cancer deaths. PM2.5 was significantly positively associated with death from cancers of the kidney {adjusted hazard ratio (HR) per 4.4 mug/m3=1.14 [95% confidence interval (CI): 1.03, 1.27]} and bladder [HR=1.13 (95% CI: 1.03, 1.23)]. NO2 was positively associated with colorectal cancer mortality [HR per 6.5 ppb=1.06 (95% CI: 1.02, 1.10). The results were similar in two-pollutant models including PM2.5 and NO2 and in three-pollutant models with O3. We observed no statistically significant positive associations with death from other types of cancer based on results from adjusted models. CONCLUSIONS: The results from this large prospective study suggest that ambient air pollution was not associated with death from most nonlung cancers, but associations with kidney, bladder, and colorectal cancer death warrant further investigation. https://doi.org/10.1289/EHP1249

Long-term exposure to ambient ozone and mortality : A quantitative systematic review and meta-analysis of evidence from cohort studies

Objectives: While there is good evidence for associations between short-term exposure to ozone and a range of adverse health outcomes, the evidence from narrative reviews for long-term exposure is suggestive of associations with respiratory mortality only. We conducted a systematic, quantitative evaluation of the evidence from cohort studies, reporting associations between long-term exposure to ozone and mortality. Methods: Cohort studies published in peer-reviewed journals indexed in EMBASE and MEDLINE to September 2015 and PubMed to October 2015 and cited in reviews/key publications were identified via search strings using terms relating to study design, pollutant and health outcome. Study details and estimate information were extracted and used to calculate standardised effect estimates expressed as HRs per 10 ppb increment in long-term ozone concentrations. Results: 14 publications from 8 cohorts presented results for ozone and all-cause and cause-specific mortality. We found no evidence of associations between long-term annual O3 concentrations and the risk of death from all causes, cardiovascular or respiratory diseases, or lung cancer. 4 cohorts assessed ozone concentrations measured during the warm season. Summary HRs for cardiovascular and respiratory causes of death derived from 3 cohorts were 1.01 (95% CI 1.00 to 1.02) and 1.03 (95% CI 1.01 to 1.05) per 10 ppb, respectively. Conclusions: Our quantitative review revealed a paucity of independent studies regarding the associations between long-term exposure to ozone and mortality. The potential impact of climate change and increasing anthropogenic emissions of ozone precursors on ozone levels worldwide suggests further studies of the long-term effects of exposure to high ozone levels are warranted

Development of a wearable global positioning system for place and health research

<p>Abstract</p> <p>Background</p> <p>An increasing number of studies suggest that characteristics of context, or the attributes of the places within which we live, work and socialize, are associated with variations in health-related behaviours and outcomes. The challenge for health research is to ensure that these places are accurately represented spatially, and to identify those aspects of context that are related to variations in health and amenable to modification. This study focuses on the design of a wearable global positioning system (GPS) data logger for the purpose of objectively measuring the temporal and spatial features of human activities. Person-specific GPS data provides a useful source of information to operationalize the concept of place.</p> <p>Results</p> <p>We designed and tested a lightweight, wearable GPS receiver, capable of logging location information for up to 70 hours continuously before recharging. The device is accurate to within 7 m in typical urban environments and performs well across a range of static and dynamic conditions.</p> <p>Discussion</p> <p>Rather than rely on static areal units as proxies for places, wearable GPS devices can be used to derive a more complete picture of the different places that influence an individual's wellbeing. The measures are objective and are less subject to biases associated with recall of location or misclassification of contextual attributes. This is important for two reasons. First, it brings a dynamic perspective to place and health research. The influence of place on health is dynamic in that certain places are more or less relevant to wellbeing as determined by the length of time in any location and by the frequency of activity in the location. Second, GPS data can be used to assess whether the characteristics of places at specific times are useful to explaining variations in health and wellbeing.</p

The Global Burden of Ozone on Respiratory Mortality: No Clear Evidence for Association

The correspondence section is a public forum and, as such, is not peer-reviewed. EHP is not responsible for the accuracy, currency, or reliability of personal opinion expressed herein; it is the sole responsibility of the authors. EHP neither endorses nor disputes their published commentary