Riccati-parameter solutions of nonlinear second-order ODEs

It has been proven by Rosu and Cornejo-Perez in 2005 that for some nonlinear second-order ODEs it is a very simple task to find one particular solution once the nonlinear equation is factorized with the use of two first-order differential operators. Here, it is shown that an interesting class of parametric solutions is easy to obtain if the proposed factorization has a particular form, which happily turns out to be the case in many problems of physical interest. The method that we exemplify with a few explicitly solved cases consists in using the general solution of the Riccati equation, which contributes with one parameter to this class of parametric solutions. For these nonlinear cases, the Riccati parameter serves as a `growth' parameter from the trivial null solution up to the particular solution found through the factorization procedureComment: 5 pages, 3 figures, change of title and more tex

The performance of Minima Hopping and Evolutionary Algorithms for cluster structure prediction

We compare Evolutionary Algorithms with Minima Hopping for global optimization in the field of cluster structure prediction. We introduce a new {\em average offspring} recombination operator and compare it with previously used operators. Minima Hopping is improved with a {\em softening} method and a stronger feedback mechanism. Test systems are atomic clusters with Lennard-Jones interaction as well as silicon and gold clusters described by force fields. The improved Minima Hopping is found to be well-suited to all these homoatomic problems. The evolutionary algorithm is more efficient for systems with compact and symmetric ground states, including LJ$_{150}$, but it fails for systems with very complex energy landscapes and asymmetric ground states, such as LJ$_{75}$ and silicon clusters with more than 30 atoms. Both successes and failures of the evolutionary algorithm suggest ways for its improvement

Phase ordering and shape deformation of two-phase membranes

Within a coupled-field Ginzburg-Landau model we study analytically phase separation and accompanying shape deformation on a two-phase elastic membrane in simple geometries such as cylinders, spheres and tori. Using an exact periodic domain wall solution we solve for the shape and phase ordering field, and estimate the degree of deformation of the membrane. The results are pertinent to a preferential phase separation in regions of differing curvature on a variety of vesicles.Comment: 4 pages, submitted to PR

Protist diversity on a nature reserve in NW England − with particular reference to their role in soil biogenic silicon pools

Soil protists play fundamental roles in many earth system processes, yet we are only beginning to understand the true diversity of the organisms involved. In this study we used conventional (microscopy-based) methods to characterise the diversity and estimate protist population sizes in soils from a variety of distinct habitats within Mere Sands Wood nature reserve in NW England. We produced population size data for over ninety soil protists belonging to two major eukaryotic functional groups: testate amoebae (TA) and diatoms, adding substantial ‘cryptic diversity’ to the nature reserves recorded biota. From these population size data we estimated relative contributions of TA and diatoms to soil biogenic silicon (BSi) pools and found significant correlations between taxon richness and the TA and diatom Si pool. This could indicate that protist functional diversity can influence terrestrial BSi pools, especially in early successional plant communities where TA and diatoms can potentially increase Si mineralisation and/or create Si ‘hot spots’ and hence, the biological availability of this element for subsequent plant uptake. TA were particularly abundant in mor humus type soils further supporting the idea that they could be important players in nutrient cycling in such soils. Overall, we demonstrate this is a useful approach in order to start to attempt to estimate the role of protists in the Si cycle and other ecological processes

Towards water and energy self-sufficiency : a closed-loop, solar-driven, low-tech laundry pilot facility (LaundReCycle) for the reuse of laundry wastewater

In the scope of this study, a pilot facility for the recycling of laundry effluent was developed and tested. With the aim to enable nearly complete energy and water self-sufficiency, the system is powered by a photovoltaic plant with second-life batteries, treats the wastewater within the unit and constantly reuses the treated wastewater for washing in a closed cycle. The technology for wastewater treatment is based on a low-tech approach consisting of a physical/mechanical pre-treatment and biological treatment in trickling filter columns. The treatment process is operated in batch mode for a capacity of five washing cycles per day. During five weeks of operation water quality, energy consumption and production, water losses and washing performance were monitored. The system recovered 69% of the used water for the washing machine while treating the wastewater to the necessary water quality levels. The average COD removal rate per cycle was 92%. Energy analysis was based on modelled data of the monitored energy consumption. With the current set-up, an internal consumption rate of 80% and self-sufficiency of 30% were modelled. Future developments aim at increasing water and energy self-sufficiency and optimizing the water treatment efficiency

Copula Eigenfaces with Attributes: Semiparametric Principal Component Analysis for a Combined Color, Shape and Attribute Model

Principal component analysis is a ubiquitous method in parametric appearance modeling for describing dependency and variance in datasets. The method requires the observed data to be Gaussian-distributed. We show that this requirement is not fulfilled in the context of analysis and synthesis of facial appearance. The model mismatch leads to unnatural artifacts which are severe to human perception. As a remedy, we use a semiparametric Gaussian copula model, where dependency and variance are modeled separately. This model enables us to use arbitrary Gaussian and non-Gaussian marginal distributions. Moreover, facial color, shape and continuous or categorical attributes can be analyzed in an unified way. Accounting for the joint dependency between all modalities leads to a more specific face model. In practice, the proposed model can enhance performance of principal component analysis in existing pipelines: The steps for analysis and synthesis can be implemented as convenient pre- and post-processing steps

Anti-PF4 immunothrombosis without proximate heparin or adenovirus vector vaccine exposure.

Platelet-activating anti-platelet factor 4 (PF4)/heparin antibodies and anti-PF4 antibodies cause heparin-induced thrombocytopenia (HIT) and vaccine-induced immune thrombocytopenia and thrombosis (VITT), respectively. Diagnostic and treatment considerations differ somewhat between HIT and VITT. We identified patients with thrombocytopenia and thrombosis without proximate heparin exposure or adenovirus-based vaccination who tested strongly positive by PF4/polyanion enzyme-immunoassays and negative/weakly positive by heparin-induced platelet activation (HIPA) test but strongly positive by PF4-induced platelet activation (PIPA) test (ie, VITT-like profile). We tested these patients by a standard chemiluminescence assay that detects anti-PF4/heparin antibodies found in HIT (HemosIL AcuStar HIT-IgG(PF4-H)) as well as a novel chemiluminescence assay for anti-PF4 antibodies found in VITT. Representative control sera included an exploratory anti-PF4 antibody-positive but HIPA-negative/weak cohort obtained before 2020 (n = 188). We identified 9 patients with a clinical-pathological profile of a VITT-like disorder in the absence of proximate heparin or vaccination, with a high frequency of stroke (arterial, n = 3; cerebral venous sinus thrombosis, n = 4), thrombocytopenia (median platelet count nadir, 49 × 109/L), and hypercoagulability (greatly elevated D-dimer levels). VITT-like serological features included strong reactivity by PIPA (aggregation <10 minutes in 9/9 sera) and positive testing in the novel anti-PF4 chemiluminescence assay (3/9 also tested positive in the anti-PF4/heparin chemiluminescence assay). Our exploratory cohort identified 13 additional patient sera obtained before 2020 with VITT-like anti-PF4 antibodies. Platelet-activating VITT-like anti-PF4 antibodies should be considered in patients with thrombocytopenia, thrombosis, and very high D-dimer levels, even without a proximate exposure to heparin or adenovirus vector vaccines

Influence of the addition of LPG-reformate and H2 on an engine dually fuelled with LPG–diesel, –RME and –GTL Fuels

AbstractDual fuel compression ignition engine has been proposed as one approach to reduce diesel engine regulated emissions (NOX and Soot) and to also allow the utilisation of other non-traditional fuels in transportation, in order to improve fuel security and CO2 emissions. In an attempt to improve the combustion characteristics of the LPG–diesel dual fuelled engine the influence of the (a) hydrogen and reformate (H2 and CO) additions and (b) properties of the in-cylinder injected diesel fuel, in this case diesel, biodiesel and synthetic diesel fuel were investigated.Improvements on engine thermal efficiency and HC (including particular HC species) emissions with the reformate and further improvements on CO, soot and particulate matter with hydrogen with respect to LPG–diesel dual fuel combustion were obtained. However, an increase in NOX was obtained due to the high in-cylinder temperature as a result of the shorter advanced premixed combustion. Moreover, the RME’s oxygen content, different injection (i.e. different high bulk modulus) and combustion characteristics as a result of its properties modified the combustion process and hence produced even lower HC, CO, soot and PM emissions. On the other hand, the lower density of GTL has changed the diesel fuel injection and combustion characteristics in dual fuelling mode which resulted in the increased regulated (HC and CO) and unregulated emissions. However, LPG–GTL dual fuelling with reformate and H2 addition showed better smoke-NOX trade-off compared to that of ULSD and RME

A Closest Point Proposal for MCMC-based Probabilistic Surface Registration

We propose to view non-rigid surface registration as a probabilistic inference problem. Given a target surface, we estimate the posterior distribution of surface registrations. We demonstrate how the posterior distribution can be used to build shape models that generalize better and show how to visualize the uncertainty in the established correspondence. Furthermore, in a reconstruction task, we show how to estimate the posterior distribution of missing data without assuming a fixed point-to-point correspondence. We introduce the closest-point proposal for the Metropolis-Hastings algorithm. Our proposal overcomes the limitation of slow convergence compared to a random-walk strategy. As the algorithm decouples inference from modeling the posterior using a propose-and-verify scheme, we show how to choose different distance measures for the likelihood model. All presented results are fully reproducible using publicly available data and our open-source implementation of the registration framework