Modelling feedbacks between the Northern Hemisphere ice sheets and climate during the last glacial cycle

During the last glacial cycle (LGC), ice sheets covered large parts of Eurasia and North America, which resulted in ∼120 m of sea level change. Ice sheet-climate interactions have considerable influence on temperature and precipitation patterns and therefore need to be included when simulating this time period. Ideally, ice sheet-climate interactions are simulated by a high-resolution Earth system model. While these models are capable of simulating climates at a certain point in time, such as the pre-industrial (PI) or the Last Glacial Maximum (LGM; 21 000 years ago), a full transient glacial cycle is currently computationally unfeasible as it requires a too-large amount of computation time. Nevertheless, ice sheet models require forcing that captures the gradual change in climate over time to calculate the accumulation and melt of ice and its effect on ice sheet extent and volume changes. Here we simulate the LGC using an ice sheet model forced by LGM and PI climates. The gradual change in climate is modelled by transiently interpolating between pre-calculated results from a climate model for the LGM and the PI. To assess the influence of ice sheet-climate interactions, we use two different interpolation methods: the climate matrix method, which includes a temperature-albedo and precipitation-topography feedback, and the glacial index method, which does not. To investigate the sensitivity of the results to the prescribed climate forcing, we use the output of several models that are part of the Paleoclimate Modelling Intercomparison Project Phase III (PMIP3). In these simulations, ice volume is prescribed, and the climate is reconstructed with a general circulation model (GCM). Here we test those models by using their climate to drive an ice sheet model over the LGC. We find that the ice volume differences caused by the climate forcing exceed the differences caused by the interpolation method. Some GCMs produced unrealistic LGM volumes, and only four resulted in reasonable ice sheets, with LGM Northern Hemisphere sea level contribution ranging between 74-113 m with respect to the present day. The glacial index and climate matrix methods result in similar ice volumes at the LGM but yield a different ice evolution with different ice domes during the inception phase of the glacial cycle and different sea level rates during the deglaciation phase. The temperature-albedo feedback is the main cause of differences between the glacial index and climate matrix methods

The CoroPrevention-SDM Approach : A Technology-supported Shared Decision Making Approach for a Comprehensive Secondary Prevention Program for Cardiac Patients

After a cardiac event, secondary prevention is recommended to foster recovery and reduce the risk of recurrent events. European guidelines and EAPC position statements on prevention of cardiovascular diseases recommend a holistic approach that actively engages patients by using shared decision making (SDM). It has been demonstrated that telerehabilitation can be a feasible and effective add-on or alternative compared to conventional in-hospital secondary prevention. However, till date, there is no eHealth solution that offers a holistic approach for secondary prevention that includes SDM. In this paper, we present the CoroPrevention-SDM approach, a technology-supported shared decision making approach for a comprehensive secondary prevention program for cardiac patients. The CoroPrevention Tool Suite consists of three applications that support patients and caregivers in following this approach: 1) a caregiver dashboard that includes decision support systems and supports SDM, 2) a patient mobile application that supports patients in making behaviour changes in their daily life, and 3) an extended ePRO application that collects patient reported outcomes and patient preferences. In a formative usability study, we assessed patients’ and caregivers’ opinion about our approach. The study indicated that both are willing to use our proposed approach to collaboratively set behavioural goals during SDM encounters.publishedVersionPeer reviewe

Protein Conformation and Supercharging with DMSO from Aqueous Solution

The efficacy of dimethyl sulfoxide (DMSO) as a supercharging reagent for protein ions formed by electrospray ionization from aqueous solution and the mechanism for supercharging were investigated. Addition of small amounts of DMSO to aqueous solutions containing hen egg white lysozyme or equine myoglobin results in a lowering of charge, whereas a significant increase in charge occurs at higher concentrations. Results from both near-UV circular dichroism spectroscopy and solution-phase hydrogen/deuterium exchange mass spectrometry indicate that DMSO causes a compaction of the native structure of these proteins at low concentration, but significant unfolding occurs at ~63% and ~43% DMSO for lysozyme and myoglobin, respectively. The DMSO concentrations required to denature these two proteins in bulk solution are ~3–5 times higher than the concentrations required for the onset of supercharging, consistent with a significantly increased concentration of this high boiling point supercharging reagent in the ESI droplet as preferential evaporation of water occurs. DMSO is slightly more basic than m-nitrobenzyl alcohol and sulfolane, two other supercharging reagents, based on calculated proton affinity and gas-phase basicity values both at the B3LYP and MP2 levels of theory, and all three of these supercharging reagents are significantly more basic than water. These results provide additional evidence that the origin of supercharging from aqueous solution is the result of chemical and/or thermal denaturation that occurs in the ESI droplet as the concentration of these supercharging reagents increases, and that proton transfer reactivity does not play a significant role in the charge enhancement observed

Macroscopic non-equilibrium thermodynamics in dynamic calorimetry

What is really measured in dynamic calorimetric experiments is still an open question. This paper is devoted to this question, which can be usefully envisaged by means of macroscopic non-equilibrium thermodynamics. From the pioneer work of De Donder on chemical reactions and with other authors along the 20th century, the question is tackled under an historical point of view. A special attention is paid about the notions of frequency dependent complex heat capacity and entropy production due to irreversible processes occurring during an experiment. This phenomenological approach based on thermodynamics, not widely spread in the literature of calorimetry, could open significant perspectives on the study of macro-systems undergoing physico-chemical transformations probed by dynamic calorimetry.Comment: review article (21 pages

Deformability of poly(amidoamine) dendrimers

Experimental data indicates that poly(amidoamine) (PAMAM) dendrimers flatten when in contact with a substrate, i.e. they are no longer spherical, but resemble flat disks. In order to better understand the deformation behavior of these branched polymers, a series of atomistic molecular dynamics simulations is performed. The resulting flattened dendrimer conformations are compared to atomic force microscopy (AFM) images of individual dendrimers at air/mica and water/mica interfaces. The ability of the polymers to deform is investigated as a function of dendrimer generation (2-5) and the required energies are calculated. Our modeling results show good agreement with the experimental AFM images, namely that dendrimers are highly flexible and capable of forming multiple interaction sites between most of their branch ends and the substrate. The deformation energy scales with dendrimer generation and does not indicate an increase in stiffness between generations 2 and 5 due to steric effects.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/45831/1/10189_2003_Article_10087.pd

Reaching ultra low phosphorus concentrations by filtration techniques

This research deals with tertiary treatment techniques used for the removal of phosphorus from wastewater treatment plant (WWTP) effluent. The main objective of this research is to obtain ultra low total phosphorus (<0.15 mg total phosphorus/L) concentrations by coagulation, flocculation and filtration of wastewater treatment plant effluent. Knowledge of the different phosphorus forms in WWTP effluent is essential to reach ultra low concentrations in the WWTP effluent. The TU Delft phosphorus distribution has been developed to have an easy and quick method to determine orthophosphorus, metal-bound phosphorus, dissolved “organic” phosphorus and particulate organic phosphorus. The phosphorus distributions make it possible to compare the phosphorus removal of different filter concepts but it can also be used to compare different settings, for example flocculation time, initial mixing energy and filtration rates. Pilot-plant investigations were conducted at the Horstermeer WWTP and the Leiden Zuidwest WWTP. Results showed that the initial mixing energy has no influence on the phosphorus size fractionation and phosphorus distribution in the upper water layer of a fixed bed filter. This means that the initial mixing energy of 300 s-1 is already sufficient. During the filtration experiments, results showed that an increasing total phosphorus concentration in the feed water results in increased total phosphorus concentrations in the filtrate water. The coagulant dosage is a major influence on the filter runtime. With increasing coagulant dosage, the filter runtime decreases. For continuous sand filtration, an increase in the total phosphorus concentration in the feed water does not lead to higher total phosphorus concentrations in the filtrate water. 1-STEP® filtration reaches higher removal efficiencies compared to dual media filtration. It is to be concluded that phosphorus removal to an ultra low concentration can be achieved, but knowledge about the different phosphorus forms and their behaviour is of major importance.Sanitary EngineeringCivil Engineering and Geoscience