Development and application of a sensitive, high precision weighing lysimeter for use in greenhouses

A high precision weighing lysimeter for measuring evapotranspiration in greenhouses was developed. The instrument has a measurement of sensitivity of one part in 106, that is one order of magnitude better than any other so far described in the literature. With it, evaporation rates in a greenhouse, even at night, can be measured on a one minute time scale. Development and construction of the instrument are described and measurements of the transpiration of a tomato crop in a greenhouse are used to demonstrate its capabilities

Solving the stationary Liouville equation via a boundary element method

Intensity distributions of linear wave fields are, in the high frequency limit, often approximated in terms of flow or transport equations in phase space. Common techniques for solving the flow equations for both time dependent and stationary problems are ray tracing or level set methods. In the context of predicting the vibro-acoustic response of complex engineering structures, reduced ray tracing methods such as Statistical Energy Analysis or variants thereof have found widespread applications. Starting directly from the stationary Liouville equation, we develop a boundary element method for solving the transport equations for complex multi-component structures. The method, which is an improved version of the Dynamical Energy Analysis technique introduced recently by the authors, interpolates between standard statistical energy analysis and full ray tracing, containing both of these methods as limiting cases. We demonstrate that the method can be used to efficiently deal with complex large scale problems giving good approximations of the energy distribution when compared to exact solutions of the underlying wave equation

Expansion and Hadronization of a Chirally Symmetric Quark--Meson Plasma

Using a chirally symmetric Lagrangian, which contains quarks as elementary degrees of freedom and mesons as bound states, we investigate the expansion and hadronization of a fireball, which initially contains only quarks and produces mesons by collisions. For this model, we study the time scales of expansion and thermal and chemical equilibration. We find that the expansion progresses relatively fast, leaving not necessarily enough time to establish thermal and chemical equilibrium. Mesons are produced in the bulk of the fireball rather than at a surface, at a temperature below the Mott temperature. Initial density fluctuations become amplified during the expansion. These observations challenge the applicability of hydrodynamical approaches to the expansion of a quark-gluon plasma

Correcting the polarization effect in low frequency Dielectric Spectroscopy

We demonstrate a simple and robust methodology for measuring and analyzing the polarization impedance appearing at interface between electrodes and ionic solutions, in the frequency range from 1 to $10^6$ Hz. The method assumes no particular behavior of the electrode polarization impedance and it only makes use of the fact that the polarization effect dies out with frequency. The method allows a direct and un-biased measurement of the polarization impedance, whose behavior with the applied voltages and ionic concentration is methodically investigated. Furthermore, based on the previous findings, we propose a protocol for correcting the polarization effect in low frequency Dielectric Spectroscopy measurements of colloids. This could potentially lead to the quantitative resolution of the $\alpha$-dispersion regime of live cells in suspension

Modeling and predicting the shape of the far-infrared to submillimeter emission in ultra-compact HII regions and cold clumps

Dust properties are very likely affected by the environment in which dust grains evolve. For instance, some analyses of cold clumps (7 K- 17 K) indicate that the aggregation process is favored in dense environments. However, studying warm (30 K-40 K) dust emission at long wavelength ($\lambda$$>$300 $\mu$m) has been limited because it is difficult to combine far infared-to-millimeter (FIR-to-mm) spectral coverage and high angular resolution for observations of warm dust grains. Using Herschel data from 70 to 500 $\mu$m, which are part of the Herschel infrared Galactic (Hi-GAL) survey combined with 1.1 mm data from the Bolocam Galactic Plane Survey (BGPS), we compared emission in two types of environments: ultra-compact HII (UCHII) regions, and cold molecular clumps (denoted as cold clumps). With this comparison we tested dust emission models in the FIR-to-mm domain that reproduce emission in the diffuse medium, in these two environments (UCHII regions and cold clumps). We also investigated their ability to predict the dust emission in our Galaxy. We determined the emission spectra in twelve UCHII regions and twelve cold clumps, and derived the dust temperature (T) using the recent two-level system (TLS) model with three sets of parameters and the so-called T-$\beta$ (temperature-dust emissvity index) phenomenological models, with $\beta$ set to 1.5, 2 and 2.5. We tested the applicability of the TLS model in warm regions for the first time. This analysis indicates distinct trends in the dust emission between cold and warm environments that are visible through changes in the dust emissivity index. However, with the use of standard parameters, the TLS model is able to reproduce the spectral behavior observed in cold and warm regions, from the change of the dust temperature alone, whereas a T-$\beta$ model requires $\beta$ to be known.Comment: Accepted for publication in A&A. 19 pages, 8 figures, 7 table

Submillimeter to centimeter excess emission from the Magellanic Clouds. II. On the nature of the excess

Dust emission at submm to cm wavelengths is often simply the Rayleigh-Jeans tail of dust particles at thermal equilibrium and is used as a cold mass tracer in various environments including nearby galaxies. However, well-sampled spectral energy distributions of the nearby, star-forming Magellanic Clouds have a pronounced (sub-)millimeter excess (Israel et al., 2010). This study attempts to confirm the existence of such a millimeter excess above expected dust, free-free and synchrotron emission and to explore different possibilities for its origin. We model NIR to radio spectral energy distributions of the Magellanic Clouds with dust, free-free and synchrotron emission. A millimeter excess emission is confirmed above these components and its spectral shape and intensity are analysed in light of different scenarios: very cold dust, Cosmic Microwave Background (CMB) fluctuations, a change of the dust spectral index and spinning dust emission. We show that very cold dust or CMB fluctuations are very unlikely explanations for the observed excess in these two galaxies. The excess in the LMC can be satisfactorily explained either by a change of the spectral index due to intrinsic properties of amorphous grains, or by spinning dust emission. In the SMC however, due to the importance of the excess, the dust grain model including TLS/DCD effects cannot reproduce the observed emission in a simple way. A possible solution was achieved with spinning dust emission, but many assumptions on the physical state of the interstellar medium had to be made. Further studies, using higher resolution data from Planck and Herschel, are needed to probe the origin of this observed submm-cm excess more definitely. Our study shows that the different possible origins will be best distinguished where the excess is the highest, as is the case in the SMC.Comment: 7 pages, 6 figures; accepted in A&

Motivational interviewing and problem solving treatment to reduce type 2 diabetes and cardiovascular disease risk in real life: a randomized controlled trial

BACKGROUND: Intensive lifestyle interventions in well-controlled settings are effective in lowering the risk of chronic diseases such as type 2 diabetes (T2DM) and cardiovascular diseases (CVD), but there are still no effective lifestyle interventions for everyday practice. In the Hoorn Prevention Study we aimed to assess the effectiveness of a primary care based lifestyle intervention to reduce the estimated risk of developing T2DM and for CVD mortality, and to motivate changes in lifestyle behaviors. METHODS: The Hoorn Prevention Study is a parallel group randomized controlled trial, implemented in the region of West-Friesland, the Netherlands. 622 adults with ≥10% estimated risk of T2DM and/or CVD mortality were randomly assigned and monitored over a period of 12 months. The intervention group (n=314) received a theory-based lifestyle intervention based on an innovative combination of motivational interviewing and problem solving treatment, provided by trained practice nurses in 12 general practices. The control group (n=308) received existing health brochures. Primary outcomes was the estimated diabetes risk according to the formula of the Atherosclerosis Risk In Communities (ARIC) Study, and the estimated risk for CVD mortality according to the Systematic COronary Risk Evaluation (SCORE) formula. Secondary outcomes included lifestyle behavior (diet, physical activity and smoking). The research assistants, the principal investigator and the general practitioners were blinded to group assignment. Linear and logistic regression analysis was applied to examine the between-group differences in each outcome measure, adjusted for baseline values. RESULTS: 536 (86.2%) of the 622 participants (age 43.5 years) completed the 6-month follow-up, and 502 (81.2%) completed the 12-month follow-up. The mean baseline T2DM risk was 18.9% (SD 8.2) and the mean CVD mortality risk was 3.8% (SD 3.0). The intervention group participated in a median of 2 sessions. Intention-to-treat analyses showed no significant differences in outcomes between the two groups at 6 or 12-months follow-up. CONCLUSIONS: The lifestyle intervention was not more effective than health brochures in reducing risk scores for T2DM and CVD or improving lifestyle behavior in an at-risk population. TRIAL REGISTRATION: Current Controlled Trials: ISRCTN59358434

Diffuse far-infrared and ultraviolet emission in the NGC4435/4438 system: tidal stream or Galactic cirrus?

We report the discovery of diffuse far-infrared and far-ultraviolet emission projected near the interacting pair NGC4435/4438, in the Virgo cluster. This feature spatially coincides with a well known low surface-brightness optical plume, usually interpreted as tidal debris. If extragalactic, this stream would represent not only one of the clearest examples of intracluster dust, but also a rare case of intracluster molecular hydrogen and large-scale intracluster star formation. However, the ultraviolet, far-infrared, HI and CO emission as well as the dynamics of this feature are extremely unusual for tidal streams but are typical of Galactic cirrus clouds. In support to the cirrus scenario, we show that a strong spatial correlation between far-infrared and far-ultraviolet cirrus emission is observed across the center of the Virgo cluster, over a scale of several degrees. This study demonstrates how dramatic Galactic cirrus contamination can be, even at optical and ultraviolet wavelengths and at high galactic latitudes. If ignored, the presence of diffuse light scattered by Galactic dust clouds could significantly bias our interpretation of low surface-brightness features and diffuse light observed around galaxies and in clusters of galaxies.Comment: 6 pages, 4 figures. Accepted for publication in MNRAS Letter