Natural and anthropogenic forcing of Holocene lake ecosystem development at Lake Uddelermeer (The Netherlands)

The majority of water bodies in the world is affected by human impact on their catchment, and pollution of freshwater ecosystems is now considered a global problem. Palaeoecological research allows to reconstruct the natural ecosystem variability of such polluted systems, and many reconstructions that date back a few centuries or beyond inform on the natural background of polluted lakes. Only a limited number of studies have so far looked at long term (e.g. Holocene) changes in lake ecosystem status, even though human impact is known to date back for several millennia in some parts of the world. We apply a combination of classic palaeoecological proxies and novel geochemical proxies in our study of the Holocene sediments of Lake Uddelermeer (The Netherlands). Lake Uddelermeer is a shallow freshwater lake that is currently characterized by turbid conditions. These are currently thought to have resulted from increased agricultural activity in the 20th century AD, but human impact in the surroundings of this site date back to 6000 BP (late Mesolithic/ early Neolithic). We show that the lake ecosystem was characterized by a mix of aquatic macrophytes and abundant phytoplankton throughout the Early and Middle Holocene (11.5-6 cal kyr BP). A transition to a lake ecosystem with clear-water conditions and relatively high abundances of ‘isoetids’ coincides with the first signs of human impact on the landscape around Lake Uddelermeer (6000 cal yr BP). An abrupt and dramatic ecosystem shift can be seen at ~1030 cal yr BP when increases in the abundance of algal microfossils and concentrations of sedimentary pigments indicate a transition to a turbid phytoplankton-dominated state. A strong increase in concentrations of faecal biomarkers can be seen only after 1950 AD, indicating that an increased input of manure-derived material into the lake is not the initial cause for eutrophication of the system. Canonical Correspondence Analysis (CCA) suggests that reconstructed lake ecosytem changes are best explained by environmental drivers that show long-term gradual changes (sediment age, water depth). These combined results document the long-term anthropogenic impact on the ecosystem of Lake Uddelermeer and provide evidence for pre-Industrial Era signs of eutrophication

Demographic, clinical and lifestyle-related correlates of accelerometer assessed physical activity and fitness in newly diagnosed patients with head and neck cancer

Introduction: Objective measurements of levels of physical activity and fitness in patients with head and neck cancer (HNC) are lacking. Furthermore, demographic, clinical and lifestyle-related correlates of low levels of physical activity and fitness in patients with HNC are unknown. This study aims to investigate the levels of accelerometer that assessed physical activity and fitness in patients with HNC and to identify their demographical, clinical and lifestyle-related correlates. Methods: Two hundred and fifty-four patients who were recently diagnosed with HNC and participated in the NETherlands QUality of life and Biomedical cohort studies In head and neck Cancer (NET-QUBIC) study were included. Physical activity (accelerometer), cardiorespiratory fitness (Chester Step Test), hand grip strength (hand dynamometer) and lower body muscle function (30-second chair-stand test) were assessed. Multivariable linear regression analyses with a stepwise forward selection procedure were used. Results: Patients spent 229 min/d in physical activity of which 18 min/d in moderate-to-vigorous physical activity. The mean predicted VO2max was 27.9 ml/kg/min, the mean hand grip strength was 38.1 kg and the mean number of standings was 14.3. Patients with lower educational level, more comorbidity and higher tumor stage spent significantly less time in physical activity. Older patients, females and patients with a higher tumor stage had significantly lower cardiorespiratory fitness levels. Older patients, females, patients with more comorbidity, patients with normal weight and patients who have never smoked had significantly lower hand grip strength. Older patients, patients with lower educational level, smokers and patients with more comorbidity had a significantly lower function of lower body muscle. Conclusions: Pre-treatment levels of physical activity, cardiorespiratory fitness and lower body muscle function are low in patients with HNC. Based on this study, exercise programs targeted and tailored to patients with low levels of physical activity and fitness can be developed

Evidence for a mixed mass composition at the `ankle' in the cosmic-ray spectrum

We report a first measurement for ultra-high energy cosmic rays of the correlation between the depth of shower maximum and the signal in the water Cherenkov stations of air-showers registered simultaneously by the fluorescence and the surface detectors of the Pierre Auger Observatory. Such a correlation measurement is a unique feature of a hybrid air-shower observatory with sensitivity to both the electromagnetic and muonic components. It allows an accurate determination of the spread of primary masses in the cosmic-ray flux. Up till now, constraints on the spread of primary masses have been dominated by systematic uncertainties. The present correlation measurement is not affected by systematics in the measurement of the depth of shower maximum or the signal in the water Cherenkov stations. The analysis relies on general characteristics of air showers and is thus robust also with respect to uncertainties in hadronic event generators. The observed correlation in the energy range around the `ankle' at $\lg(E/{\rm eV})=18.5-19.0$ differs significantly from expectations for pure primary cosmic-ray compositions. A light composition made up of proton and helium only is equally inconsistent with observations. The data are explained well by a mixed composition including nuclei with mass $A > 4$. Scenarios such as the proton dip model, with almost pure compositions, are thus disfavoured as the sole explanation of the ultrahigh-energy cosmic-ray flux at Earth.Comment: Published version. Added journal reference and DOI. Added Report Numbe

Techniques for measuring aerosol attenuation using the Central Laser Facility at the Pierre Auger Observatory

The Pierre Auger Observatory in Malargüe, Argentina, is designed to study the properties of ultra-high energy cosmic rays with energies above 10(18) eV. It is a hybrid facility that employs a Fluorescence Detector to perform nearly calorimetric measurements of Extensive Air Shower energies. To obtain reliable calorimetric information from the FD, the atmospheric conditions at the observatory need to be continuously monitored during data acquisition. In particular, light attenuation due to aerosols is an important atmospheric correction. The aerosol concentration is highly variable, so that the aerosol attenuation needs to be evaluated hourly. We use light from the Central Laser Facility, located near the center of the observatory site, having an optical signature comparable to that of the highest energy showers detected by the FD. This paper presents two procedures developed to retrieve the aerosol attenuation of fluorescence light from CLF laser shots. Cross checks between the two methods demonstrate that results from both analyses are compatible, and that the uncertainties are well understood. The measurements of the aerosol attenuation provided by the two procedures are currently used at the Pierre Auger Observatory to reconstruct air shower data

The rapid atmospheric monitoring system of the Pierre Auger Observatory

The Pierre Auger Observatory is a facility built to detect air showers produced by cosmic rays above 10(17) eV. During clear nights with a low illuminated moon fraction, the UV fluorescence light produced by air showers is recorded by optical telescopes at the Observatory. To correct the observations for variations in atmospheric conditions, atmospheric monitoring is performed at regular intervals ranging from several minutes (for cloud identification) to several hours (for aerosol conditions) to several days (for vertical profiles of temperature, pressure, and humidity). In 2009, the monitoring program was upgraded to allow for additional targeted measurements of atmospheric conditions shortly after the detection of air showers of special interest, e. g., showers produced by very high-energy cosmic rays or showers with atypical longitudinal profiles. The former events are of particular importance for the determination of the energy scale of the Observatory, and the latter are characteristic of unusual air shower physics or exotic primary particle types. The purpose of targeted (or 'rapid') monitoring is to improve the resolution of the atmospheric measurements for such events. In this paper, we report on the implementation of the rapid monitoring program and its current status. The rapid monitoring data have been analyzed and applied to the reconstruction of air showers of high interest, and indicate that the air fluorescence measurements affected by clouds and aerosols are effectively corrected using measurements from the regular atmospheric monitoring program. We find that the rapid monitoring program has potential for supporting dedicated physics analyses beyond the standard event reconstruction

The Pierre Auger Observatory Status And Latest Results

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Astrophysical Interpretation Of Pierre Auger Observatory Measurements Of The Uhecr Energy Spectrum And Mass Composition

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Evidence For A Mixed Mass Composition At The ‘ankle’ In The Cosmic-ray Spectrum

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Depth Of Maximum Of Air-shower Profiles At The Pierre Auger Observatory. I. Measurements At Energies Above 1017.8ev

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The Rapid Atmospheric Monitoring System of the Pierre Auger Observatory

The Pierre Auger Observatory is a facility built to detect air showers produced by cosmic rays above 10^17 eV. During clear nights with a low illuminated moon fraction, the UV fluorescence light produced by air showers is recorded by optical telescopes at the Observatory. To correct the observations for variations in atmospheric conditions, atmospheric monitoring is performed at regular intervals ranging from several minutes (for cloud identification) to several hours (for aerosol conditions) to several days (for vertical profiles of temperature, pressure, and humidity). In 2009, the monitoring program was upgraded to allow for additional targeted measurements of atmospheric conditions shortly after the detection of air showers of special interest, e.g., showers produced by very high-energy cosmic rays or showers with atypical longitudinal profiles. The former events are of particular importance for the determination of the energy scale of the Observatory, and the latter are characteristic of unusual air shower physics or exotic primary particle types. The purpose of targeted (or "rapid") monitoring is to improve the resolution of the atmospheric measurements for such events. In this paper, we report on the implementation of the rapid monitoring program and its current status. The rapid monitoring data have been analyzed and applied to the reconstruction of air showers of high interest, and indicate that the air fluorescence measurements affected by clouds and aerosols are effectively corrected using measurements from the regular atmospheric monitoring program. We find that the rapid monitoring program has potential for supporting dedicated physics analyses beyond the standard event reconstruction