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Abstract We work with spaces of periodic functions on the d -dimensional torus. We show that estimates for L ∞ -approximation of Sobolev functions remain valid when we replace L ∞ by the isotropic periodic Besov space B ∞ , 1 0 or the periodic Besov space with dominating mixed smoothness S ∞ , 1 0 B. For t > 1 / 2 , we also prove estimates for L 2 -approximation of functions in the Besov space of dominating mixed smoothness S 1 , ∞ t B , describing exactly the dependence of the involved constants on the dimension d and the smoothness t. [ABSTRACT FROM AUTHOR]

In this paper, we present the implementation and evaluation of the aerosol microphysics module SALSA2.0 in the framework of the aerosol-chemistry-climate model ECHAM-HAMMOZ. It is an alternative microphysics module to the default modal microphysics scheme M7 in ECHAM-HAMMOZ. The SALSA2.0 implementation within ECHAM-HAMMOZ is evaluated against observations of aerosol optical properties, aerosol mass, and size distributions, comparing also to the skill of the M7 implementation. The largest differences between the implementation of SALSA2.0 and M7 are in the methods used for calculating microphysical processes, i.e., nucleation, condensation, coagulation, and hydration. These differences in the microphysics are reflected in the results so that the largest differences between SALSA2.0 and M7 are evident over regions where the aerosol size distribution is heavily modified by the microphysical processing of aerosol particles. Such regions are, for example, highly polluted regions and regions strongly affected by biomass burning. In addition, in a simulation of the 1991 Mt. Pinatubo eruption in which a stratospheric sulfate plume was formed, the global burden and the effective radii of the stratospheric aerosol are very different in SALSA2.0 and M7. While SALSA2.0 was able to reproduce the observed time evolution of the global burden of sulfate and the effective radii of stratospheric aerosol, M7 strongly overestimates the removal of coarse stratospheric particles and thus underestimates the effective radius of stratospheric aerosol. As the mode widths of M7 have been optimized for the troposphere and were not designed to represent stratospheric aerosol, the ability of M7 to simulate the volcano plume was improved by modifying the mode widths, decreasing the standard deviations of the accumulation and coarse modes from 1.59 and 2.0, respectively, to 1.2 similar to what was observed after the Mt. Pinatubo eruption. Overall, SALSA2.0 shows promise in improving the aerosol description of ECHAM-HAMMOZ and can be further improved by implementing methods for aerosol processes that are more suitable for the sectional method, e.g., size-dependent emissions for aerosol species and size-resolved wet deposition. [ABSTRACT FROM AUTHOR]

Within the framework of the global chemistry climate model ECHAM-HAMMOZ, a novel explicit coupling between the sectional aerosol model HAM-SALSA and the chemistry model MOZ was established to form isoprenederived secondary organic aerosol (iSOA). Isoprene oxidation in the chemistry model MOZ is described by a semiexplicit scheme consisting of 147 reactions embedded in a detailed atmospheric chemical mechanism with a total of 779 reactions. Semi-volatile and low-volatile compounds produced during isoprene photooxidation are identified and explicitly partitioned by HAM-SALSA. A group contribution method was used to estimate their evaporation enthalpies and corresponding saturation vapor pressures, which are used by HAM-SALSA to calculate the saturation concentration of each iSOA precursor. With this method, every single precursor is tracked in terms of condensation and evaporation in each aerosol size bin. This approach led to the identification of dihydroxy dihydroperoxide (ISOP(OOH)2) as a main contributor to iSOA formation. Further, the reactive uptake of isoprene epoxydiols (IEPOXs) and isoprene-derived glyoxal were included as iSOA sources. The parameterization of IEPOX reactive uptake includes a dependency on aerosol pH value. This model framework connecting semi-explicit isoprene oxidation with explicit treatment of aerosol tracers leads to a global annual average isoprene SOA yield of 15% relative to the primary oxidation of isoprene by OH, NO3 and ozone. With 445.1 Tg (392.1 Tg C) isoprene emitted, an iSOA source of 138.5 Tg (56.7 Tg C) is simulated. The major part of iSOA in ECHAM-HAMMOZ is produced by IEPOX at 42.4 Tg (21.0 Tg C) and ISOP(OOH)2 at 78.0 Tg (27.9 Tg C). The main sink process is particle wet deposition, which removes 133.6 (54.7 Tg C). The average iSOA burden reaches 1.4 Tg (0.6 Tg C) in the year 2012. [ABSTRACT FROM AUTHOR]

In this paper, we present the implementation and evaluation of the aerosol microphysics module SALSA2.0 in the framework of the aerosol-chemistry-climate model ECHAM-HAMMOZ. It is an alternative microphysics module to the default modal microphysics scheme M7 in ECHAM-HAMMOZ. The SALSA2.0 implementation is evaluated against the observations of aerosol optical properties, aerosol mass, and size distributions. We also compare the skill of SALSA2.0 in reproducing the observed quantities to the skill of the M7 implementation. The largest differences between SALSA2.0 and M7 are evident over regions where the aerosol size distribution is heavily modified by the microphysical processing of aerosol particles. Such regions are, for example, highly polluted regions and regions strongly affected by biomass burning. In addition, in a simulation of the 1991 Mt Pinatubo eruption in which a stratospheric sulfate plume was formed, the global burden and the effective radii of the stratospheric aerosol are very different in SALSA2.0 and M7. While SALSA2.0 was able to reproduce the observed time evolution of the global burden of sulfate and the effective radii of stratospheric aerosol, M7 strongly overestimates the removal of coarse stratospheric particles and thus underestimates the effective radius of stratospheric aerosol. As the mode widths of M7 have been optimized for the troposphere and were not designed to represent stratospheric aerosol the ability of M7 to simulate the volcano plume was improved by modifying the mode widths decreasing the standard deviations of the accumulation and coarse modes from 1.59 and 2.0, respectively, to 1.2. Overall, SALSA2.0 shows promise in improving the aerosol description of ECHAM-HAMMOZ and can be further improved by implementing methods for aerosol processes that are more suitable for the sectional method, e.g size dependent emissions for aerosol species and size resolved wet deposition. [ABSTRACT FROM AUTHOR]

Within the framework of the global chemistry climate model ECHAM-HAMMOZ a novel explicit coupling between the sectional aerosol model HAM-SALSA and the chemistry model MOZ was established to form isoprene derived secondary organic aerosol (iSOA). Isoprene oxidation in the chemistry model MOZ is described by a semi-explicit scheme consisting of 147 reactions, embedded in a detailed atmospheric chemical mechanism with a total of 779 reactions. Low volatile compounds (LVOC) produced during isoprene photooxidation are identified and explicitly partitioned by HAM-SALSA. A group contribution method was used to estimate their evaporation enthalpies and corresponding saturation vapor pressures, which are used by HAM-SALSA to calculate the saturation concentration of each LVOC. With this method, every single precursor is tracked in terms of condensation and evaporation in each aerosol size bin. This approach lead to the identification of ISOP(OOH)2 as a main contributor to iSOA formation. Further, reactive uptake of isoprene epoxidiols (IEPOX) and isoprene derived glyoxal were included as iSOA sources. The parameterization of IEPOX reactive uptake includes a dependency on aerosol pH value. This model framework connecting semi-explicit isoprene oxidation with explicit treatment of aerosol tracers leads to a global, annual isoprene SOA yield of 16 % relative to the primary oxidation of isoprene by OH, NO3, and ozone. With 445 Tg (392 TgC) isoprene emitted, an iSOA source of 148 Tg (61 TgC) is simulated. The major part of iSOA in ECHAM-HAMMOZ is produced by IEPOX (24.4 TgC) and ISOP(OOH)2 (28.3 TgC). The main sink process is particle wet deposition which removes 143 Tg (59 TgC). The iSOA burden reaches 1.6 Tg (0.7 TgC) in the year 2012. [ABSTRACT FROM AUTHOR]

In this paper, we reveal a new connection between approximation numbers of periodic Sobolev type spaces, where the smoothness weights on the Fourier coefficients are induced by a (quasi-)norm ∥⋅∥ on Rd, and entropy numbers of the embedding id : ℓ∥⋅∥d → ℓ∞d. This connection yields preasymptotic error bounds for approximation numbers of isotropic Sobolev spaces, spaces of analytic functions, and spaces of Gevrey type in L2 and H¹, which find application in the context of Galerkin methods. Moreover, we observe that approximation numbers of certain Gevrey type spaces behave preasymptotically almost identical to approximation numbers of spaces of dominating mixed smoothness. This observation can be exploited, for instance, for Galerkin schemes for the electronic Schrödinger equation, where mixed regularity is present. [ABSTRACT FROM AUTHOR]

The well-known Gevrey classes consist of C ∞ -functions on R d whose derivatives satisfy certain growth conditions. For periodic functions these conditions can be expressed in terms of Fourier coefficients. Motivated by this observation, we introduce Gevrey spaces on the d -dimensional torus and study approximation numbers of their embeddings into L 2. Our special emphasis is on the dependence on the dimension of the underlying domain, which is an important aspect in the numerical treatment of high-dimensional problems. In particular, we determine the exact rate of decay of the approximation numbers, together with optimal asymptotic constants, and establish preasymptotic estimates. Finally we translate our findings into the language of tractability notions from information-based complexity. [ABSTRACT FROM AUTHOR]

Using tools from the theory of operator ideals and s -numbers, we develop a general approach to transfer estimates for L 2 -approximation of Sobolev functions into estimates for L ∞ -approximation, with precise control of all involved constants. As an illustration, we derive some results for periodic isotropic Sobolev spaces H s ( T d ) and Sobolev spaces of dominating mixed smoothness H mix s ( T d ) , always equipped with natural norms. Some results for L p -approximation ( 2 < p < ∞ ) are also obtained. [ABSTRACT FROM AUTHOR]

We investigate the approximation of d-variate periodic functions in Sobolev spaces of dominating mixed (fractional) smoothness $$s>0$$ on the d-dimensional torus, where the approximation error is measured in the $$L_2$$ -norm. In other words, we study the approximation numbers $$a_n$$ of the Sobolev embeddings $$H^s_\mathrm{mix}(\mathbb {T}^d)\hookrightarrow L_2(\mathbb {T}^d)$$ , with particular emphasis on the dependence on the dimension d. For any fixed smoothness $$s>0$$ , we find two-sided estimates for the approximation numbers as a function in n and d. We observe super-exponential decay of the constants in d, if n, the number of linear samples of f, is large. In addition, motivated by numerical implementation issues, we also focus on the error decay that can be achieved by approximations using only a few linear samples (small n). We present some surprising results for the so-called 'preasymptotic' decay and point out connections to the recently introduced notion of quasi-polynomial tractability of approximation problems. [ABSTRACT FROM AUTHOR]

We investigate optimal linear approximations (approximation numbers) in the context of periodic Sobolev spaces Hs(Td) of fractional smoothness s > 0 for various equivalent norms including the classical one. The error is always measured in L2(Td). Particular emphasis is given to the dependence of all constants on the dimension d. We capture the exact decay rate in n and the exact decay order of the constants with respect to d, which is in fact polynomial. As a consequence we observe that none of our considered approximation problems suffers from the curse of dimensionality. Surprisingly, the square integrability of all weak derivatives up to order three (classical Sobolev norm) guarantees weak tractability of the associated multivariate approximation problem. [ABSTRACT FROM AUTHOR]

We establish compactness results for extrapolation constructions which correspond to the well-known Lions-Peetre compactness theorems of interpolation theory. Applications are given to compactness of certain limiting Sobolev embeddings. [ABSTRACT FROM AUTHOR]

Aims and background: Release of 'non-exchangeable' potassium (K) from interlayers of illite is diffusion-controlled and has been shown to depend on the solution concentration of K and other cations (Ca, Mg, NH). Methods: We analysed changes in soil solution concentrations of K and competing cations in situ at different distances from the root surface over time and related them to the transformation of illite, as revealed by X-ray diffraction, and chemical measures of differently bound K. Results and Conclusions: Within 49 and 98 days, respectively, 6.4 and 14.4 % of the illite's total K was released upon contact with the root system. Mixed layered minerals increased from 33 (0 d) to 35 (49 d) to 40 % (98 d). Release of K from interlayers and the transformation of illite occurred at soil solution K concentrations close to the threshold of 80 μM suggested earlier. Concentrations of Ca and Mg increased with decreasing distance from the root surface, promoting the release of K. The NaBPh method supposed to determine 'non-exchangeable' K extracted only 1/3 of the total K from illite. [ABSTRACT FROM AUTHOR]

Abstract: We establish abstract extrapolation results for entropy numbers of operators in Banach spaces. The results apply to extrapolation in the source spaces and also in the target spaces. As an illustration of the abstract results, applications to limiting Sobolev embeddings are given. [Copyright &y& Elsevier]

Abstract: We consider limiting real interpolation spaces defined by using powers of iterated logarithms and show their description by means of the J-functional. Our results allow to complement some estimates on approximation of stochastic integrals. [Copyright &y& Elsevier]

Abstract: Metric entropy quantities, like covering numbers or entropy numbers, and positive definite kernels play an important role in mathematical learning theory. Using smoothness properties of the Fourier transform of the kernels, Zhou [D.-X. Zhou, The covering number in learning theory, J. Complexity 18 (3) (2002) 739–767] proved an upper estimate for the covering numbers of the unit ball of Gaussian reproducing kernel Hilbert spaces (RKHSs), considered as a subset of the space of continuous functions. In this note we determine the exact asymptotic order of these covering numbers, exploiting an explicit description of Gaussian RKHSs via orthonormal bases. We show that Zhou’s estimate is almost sharp (up to a double logarithmic factor), but his conjecture on the correct asymptotic rate is far too optimistic. Moreover we give an application of our entropy results to small deviations of certain smooth Gaussian processes. [Copyright &y& Elsevier]

We introduce a new method for mesoscopic modeling of protein diffusion in an entire cell. This method is based on the construction of a three-dimensional digital model cell from confocal microscopy data. The model cell is segmented into the cytoplasm, nucleus, plasma membrane, and nuclear envelope, in which environment protein motion is modeled by fully numerical mesoscopic methods. Finer cellular structures that cannot be resolved with the imaging technique, which significantly affect protein motion, are accounted for in this method by assigning an effective, position-dependent porosity to the cell. This porosity can also be determined by confocal microscopy using the equilibrium distribution of a non-binding fluorescent protein. Distinction can now be made within this method between diffusion in the liquid phase of the cell (cytosol/nucleosol) and the cytoplasm/nucleoplasm. Here we applied the method to analyze fluorescence recovery after photobleach (FRAP) experiments in which the diffusion coefficient of a freely-diffusing model protein was determined for two different cell lines, and to explain the clear difference typically observed between conventional FRAP results and those of fluorescence correlation spectroscopy (FCS). A large difference was found in the FRAP experiments between diffusion in the cytoplasm/nucleoplasm and in the cytosol/nucleosol, for all of which the diffusion coefficients were determined. The cytosol results were found to be in very good agreement with those by FCS. [ABSTRACT FROM AUTHOR]

Abstract: We estimate Weyl numbers and eigenvalues of operators via studying their abstract summing norms. In particular we prove estimates of these summing norms for abstract interpolation Lorentz spaces. For this we combine factorization theorems with estimates of concavity constants. Finally we apply our general eigenvalue results to integral operators with kernels of weakly singular type. We obtain asymptotically optimal estimates which extend the well-known classical results. [Copyright &y& Elsevier]

Abstract: We determine the exact asymptotic behaviour of entropy and approximation numbers of the limiting restriction operator , defined by . Here is a non-empty bounded domain in , is an increasing slowly varying function, , and is the Besov space of generalized smoothness given by the function . Our results improve and extend those established by Leopold [Embeddings and entropy numbers in Besov spaces of generalized smoothness, in: Function Spaces, Lecture Notes in Pure and Applied Mathematics, vol. 213, Marcel Dekker, New York, 2000, pp. 323–336]. [Copyright &y& Elsevier]

Abstract: We determine the exact asymptotic behaviour of entropy numbers of diagonal operators from to , , under mild regularity conditions on the generating diagonal sequence. On one hand, this is a quantitative version of Pitt''s theorem for diagonal operators, and on the other hand it is a limiting case of results by Carl. An application to embeddings of weighted Besov and Triebel–Lizorkin spaces is also given. [Copyright &y& Elsevier]

For real Hilbert spaces Hi with 2 ≤ dim Hi ≤ 4 we determine the norm of the embedding B(H1, H2, H3) ↪ S1 (H1, H2, H3) of trilinear Schatten-von Neumann classes [ABSTRACT FROM AUTHOR]

We investigate the asymptotic behavior of the entropy numbers ot the compact embedding Bp1,q1s1(Rd, α) ↪ Bp2,q2s2(Rd). Here Bp,qs (Rd, α) denotes a weighted Besov space, where the weight is given by wα(x) = (1 + ∣x∣ ²)α/2, and Bp2,q2s2 (Rd) denotes the unweighted Besov space, respectively. We shall concentrate on the so-called limiting situation given by the following constellation of parameters: s2 < s1, 0 < p1, p2 ⩽ ∞, and α = s1 - d/p1 -s2 + d/p2 > max (0, 1/p2 - 1/p1. In almost all cases we give a sharp two-sided estimate. [ABSTRACT FROM AUTHOR]

Let RBp,qs(Rn) be the radial subspace of the Besov space Bp,qs(Rn). We prove the independence of the asymptotic behavior of the entropy numbersek(id : RBp0,q0s0(Rn)↦RBp1,q1s1(Rn))from the difference s0−s1 as long as the embedding itself RBp0,q0s0(Rn)↪RBp1,q1s1(Rn) is compact. In fact, we shall show thatek(id : RBp0,q0s0(Rn)↦RBp1,q1s1(Rn))∼k−n(1/p0−1/p1−1/p1).This is in a certain contrast to earlier results on entropy numbers in the context of Besov spaces Bp,qs(Ω) on bounded domains Ω. [Copyright &y& Elsevier]

Let 1 < p < ∞, 0 < v < p′, let Ω be a bounded domain in Rn, and denote by idΩ the limiting compact embedding of the Besov space Bppn/p(Rn) into the exponential Orlicz space Lexp(tv)(Ω), mapping a function f onto its restriction f|Ω. In 1993 Triebel established, among others, two‐sided estimates for the entropy numbers of idΩ, which are even asymptotically optimal for ‘small’ ν. The aim of the paper is to improve the upper bounds in the case of ‘large’ ν, where Triebel's estimates are not yet sharp, thus making a further step towards the conjectured correct asymptotic behaviour. [ABSTRACT FROM PUBLISHER]

Upper and lower bounds are established for the entropy numbers of certain diagonal operators between Banach sequence spaces. These diagonal operators are isomorphisms between the spaces considered in the paper and weighted sequence spaces considered by Leopold so that the entropy numbers in question coincide with those considered by Leopold. The results in the paper improve the previous results in at least two ways. The estimates in the paper are 'almost' sharp in the sense that the upper and lower estimates differ only by logarithmic factors for a much wider range of parameters. Moreover, all the upper estimates are improvements on the previous ones, the improvement being quite significant in some cases. [ABSTRACT FROM PUBLISHER]

We continue the research on the asymptotic and preasymptotic decay of singular numbers for tensor product Hilbert–Sobolev type embeddings in high dimensions with special emphasis on the influence of the underlying dimension d. The main focus in this paper lies on tensor products involving univariate Sobolev type spaces with different smoothness. We study the embeddings into L 2 and H 1. In other words, we investigate the worst-case approximation error measured in L 2 and H 1 when only n linear measurements of the function are available. Recent progress in the field shows that accurate bounds on the singular numbers are essential for recovery bounds using only function values. The asymptotic bounds in our setting are known for a long time. In this paper we contribute the correct asymptotic constant and explicit bounds in the preasymptotic range for n. We complement and improve on several results in the literature. In addition, we refine the error bounds coming from the setting where the smoothness vector is moderately increasing, which has been already studied by Papageorgiou and Woźniakowski. [ABSTRACT FROM AUTHOR]

In a previous paper, the authors laid the foundations of a theory of Schatten-von Neumann classes 5p (0<1), and for two-bounded forms. Finally, the domination problem is investigated in the trilinear set-up. [ABSTRACT FROM AUTHOR]

The influence of secondary organic aerosol (SOA) on climate is still poorly constrained, thus SOA contributes a large amount of uncertainty to current climate projections. To improve our understanding of the role of SOA in the atmosphere, further measurement campaigns and modelling studies will be necessary. Here we introduce a volatility basis set (VBS) SOA scheme to the aerosol-climate model ECHAM-HAM-SALSA, which models the oxidation of volatile organic compounds (VOC) to form SOA precursor gases and their successive partitioning into the aerosol phase. Both biogenic and anthropogenic VOC sources are considered. We evaluate our model results against a wide range of observational data, including ground-based and airborne mass spectrometry data and find generally good agreement between model and observations. Also the modelled AOD agrees better with satellite retrievals in regions where large amounts of organics are emitted. We further performed several sensitivity studies with the model to investigate how SOA volatility affects SOA burden and CCN concentrations. Interestingly, decreasing the SOA volatility leads to a larger SOA burden, but does not necessarily increase CCN concentrations. [ABSTRACT FROM AUTHOR]

We consider general linear approximation spaces Xqb based on a quasi-Banach space X, and we analyze the degree of compactness of the embedding Xqb↪X. Applications are given to periodic Besov spaces on the d-torus, including spaces of generalized and logarithmic smoothness. In particular, we obtain the exact asymptotic behavior of approximation and entropy numbers of embeddings of such Besov spaces in Lebesgue spaces and in Besov spaces of logarithmic smoothness. [ABSTRACT FROM AUTHOR]

Let B p , q s , α ( Ω ) be the Besov space with classical smoothness s and additional logarithmic smoothness of order α on a bounded Lipschitz domain Ω in R d . For s 1 , s 2 ∈ R , 1 ≤ p 1 , p 2 , q 1 , q 2 ≤ ∞ and s 1 − s 2 = d − d ( 1 ∕ p 2 − 1 ∕ p 1 ) + , we show a sufficient condition on q 1 , q 2 for nuclearity of embedding B p 1 , q 1 s 1 , α 1 ( Ω ) ↪ B p 2 , q 2 s 2 , α 2 ( Ω ) . We also show that the condition is necessary in a wide range of parameters. [ABSTRACT FROM AUTHOR]

Objective To investigate influences on the interaction between preterm infants and their parents by a dedicated parental training program on the care of preterm infants. Methods Standardized scenarios of mother–child interactions (50 mother–child dyads of very low birth weight infants (VLBWI), birth weight < 1500 g) were videotaped in two perinatal centers (PC-A, PC-B). The videos were reviewed and scored using a standardized instrument. In both centers, parents were integrated in the daily care by pediatric nurses, while additionally PC-A had a structured parental training program. Results PC-A and PC-B were comparable regarding patient spectrum and number of admissions of VLBWIs/year. Both centers had similar care values with respect to the “baby friendly” initiative. No significant differences were seen in characteristics of patients (gestational age, birth weight, postnatal age) and mothers (age, parity, marital status, professions). However, in scoring the mother–child interactions significant differences were observed: In contrast to PC-B the recorded behavior in mother–child dyads of PC-A was significantly more often scored as interaction-oriented. Conclusion A dedicated, structured, and actively encouraging training program for parents of preterm infants was found to be more strongly correlated toward neurodevelopmental enhancing mother–child-interactions than an approach of merely integrating parents into daily care routine. [ABSTRACT FROM AUTHOR]

Abstract: We investigate the limit class of interpolation spaces that comes up by the choice in the definition of the real method. These spaces arise naturally interpolating by the J-method associated to the unit square. Their duals coincide with the other extreme spaces obtained by the choice . We also study the behavior of compact operators under these two extreme interpolation methods. Moreover, we establish some interpolation formulae for function spaces and for spaces of operators. [Copyright &y& Elsevier]

So far trilinear forms have mostly been considered in low dimensions, in particular the dimension two (binary) case, and when the ring of scalars K is either the real numbers R or the complex ones C. The main aim in both situations has been to decide when a normalized form has norm unity. Here we consider the case of quaternions, K = H. This note is rather preliminary, and somewhat experimental, where the computer program Mathematica plays a certain role. A preliminary result obtained is that the form has norm unity if and only if the discriminant of a certain 5-dimensional quadratic form has all its principal minors nonnegative. We found also a rather unexpected similarity between the noncommutative case of H and the commutative one of R and C. [ABSTRACT FROM AUTHOR]

In this study we introduce an in-cloud wet deposition scheme for liquid and ice phase clouds for global aerosol–climate models which use a size-segregated aerosol description. For in-cloud nucleation scavenging, the scheme uses cloud droplet activation and ice nucleation rates obtained from the host model. For in-cloud impaction scavenging, we used a method where the removal rate depends on the wet aerosol size and cloud droplet radii. We used the latest release version of ECHAM-HAMMOZ (ECHAM6.3-HAM2.3-MOZ1.0) with the Sectional Aerosol module for Large Scale Applications version 2.0 (SALSA) microphysics package to test and compare our scheme. The scheme was compared to a scheme that uses fixed scavenging coefficients. The comparison included vertical profiles and mass and number distributions of wet deposition fluxes of different aerosol compounds and for different latitude bands. Using the scheme presented here, mass concentrations for black carbon, organic carbon, sulfate, and the number concentration of particles with diameters larger than 100 nm are higher than using fixed scavenging coefficients, with the largest differences in the vertical profiles in the Arctic. On the other hand, the number concentrations of particles smaller than 100 nm in diameter show a decrease, especially in the Arctic region. These results could indicate that, compared to fixed scavenging coefficients, nucleation scavenging is less efficient, resulting in an increase in the number concentration of particles larger than 100 nm. In addition, changes in rates of impaction scavenging and new particle formation (NPF) can be the main cause of reduction in the number concentrations of particles smaller than 100 nm. Without further adjustments in the host model, our wet deposition scheme produced unrealistically high aerosol concentrations, especially at high altitudes. This also leads to a spuriously long lifetime of black carbon aerosol. To find a better setup for simulating aerosol vertical profiles and transport, sensitivity simulations were conducted where aerosol emission distribution and hygroscopicity were altered. Vertical profiles of aerosol species simulated with the scheme which uses fixed scavenging rates and the abovementioned sensitivity simulations were evaluated against vertical profiles from aircraft observations. The lifetimes of different aerosol compounds were also evaluated against the ensemble mean of models involved in the Aerosol Comparisons between Observations and Models (AEROCOM) project. The best comparison between the observations and the model was achieved with our wet deposition scheme when black carbon was emitted internally mixed with soluble compounds instead of keeping it externally mixed. This also produced atmospheric lifetimes for the other species which were comparable to the AEROCOM model means. [ABSTRACT FROM AUTHOR]

Modeling is requiring increasingly larger efforts while becoming indispensable given the complexity of the problems we are solving. Modelers face high cognitive load to understand a multitude of complex abstractions and their relationships. There is an urgent need to better support tool builders to ultimately provide modelers with intelligent modeling assistance that learns from previous modeling experiences, automatically derives modeling knowledge, and provides context-aware assistance. However, current intelligent modeling assistants (IMAs) lack adaptability and flexibility for tool builders, and do not facilitate understanding the differences and commonalities of IMAs for modelers. Such a patchwork of limited IMAs is a lost opportunity to provide modelers with better support for the creative and rigorous aspects of software engineering. In this expert voice, we present a conceptual reference framework (RF-IMA) and its properties to identify the foundations for intelligent modeling assistance. For tool builders, RF-IMA aims to help build IMAs more systematically. For modelers, RF-IMA aims to facilitate comprehension, comparison, and integration of IMAs, and ultimately to provide more intelligent support. We envision a momentum in the modeling community that leads to the implementation of RF-IMA and consequently future IMAs. We identify open challenges that need to be addressed to realize the opportunities provided by intelligent modeling assistance. [ABSTRACT FROM AUTHOR]

In this study we introduce an in-cloud wet deposition scheme for liquid and ice phase clouds for global aerosol-climate models which use a size-segregated aerosol description. For in-cloud nucleation scavenging, the scheme uses cloud droplet activation and ice nucleation rates obtained from the host model. For in-cloud impaction scavenging, we used a method where the removal rate depends on the aerosol size and cloud droplet radii. The scheme was compared to a scheme that uses fixed scavenging coefficients. The comparison included vertical profiles and mass and number distributions of wet deposition fluxes of different aerosol compounds and for different latitude bands. Using the scheme presented here, mass concentrations for black carbon, organic carbon, sulfate, and the number concentration of particles with diameters larger than 100nm are higher than using fixed scavenging coefficients, with the largest differences in the vertical profiles in the Arctic. On the other hand, the number concentrations of small particles show a decrease, especially in the Arctic region. These results indicate that, compared to using fixed scavenging coefficients, nucleation scavenging is less efficient and impaction scavenging is increased in the scheme introduced here. Without further adjustments in the host model, our wet deposition scheme produced unrealistically high aerosol concentrations, especially at high altitudes. This also leads to a spuriously long lifetime of black carbon aerosol. To find a better setup for simulating aerosol vertical profiles and transport, sensitivity simulations were conducted where aerosol emission distribution and hygroscopicity were altered. The simulated vertical profiles of aerosol in these sensitivity studies were evaluated against aircraft observations. The lifetimes of different aerosol compounds were also evaluated against the ensemble mean of models involved in the Aerosol Comparisons between Observations and Models (AEROCOM) project. The best comparison between the observations and the model was achieved with the new wet deposition scheme when black carbon was emitted internally mixed with soluble compounds instead of keeping it externally mixed. This also produced atmospheric lifetimes for the other species which were comparable to the AEROCOM model means. [ABSTRACT FROM AUTHOR]

Satellite data suggest that summertime aerosol optical depth (AOD) over the southeastern USA depends on the air/land surface temperature, but the magnitude of the radiative effects caused by this dependence remains unclear. To quantify these radiative effects, we utilized several remote sensing datasets and ECMWF reanalysis data for the years 2005–2011. In addition, the global aerosol–climate model ECHAM-HAMMOZ was used to identify the possible processes affecting aerosol loads and their dependence on temperature over the studied region. The satellite-based observations suggest that changes in the total summertime AOD in the southeastern USA are mainly governed by changes in anthropogenic emissions. In addition, summertime AOD exhibits a dependence on southerly wind speed and land surface temperature (LST). Transport of sea salt and Saharan dust is the likely reason for the wind speed dependence, whereas the temperature-dependent component is linked to temperature-induced changes in the emissions of biogenic volatile organic compounds (BVOCs) over forested regions. The remote sensing datasets indicate that the biogenic contribution increases AOD with increasing temperature by approximately (7 ± 6) × 10−3 K−1 over the southeastern USA. In the model simulations, the increase in summertime AOD due to temperature-enhanced BVOC emissions is of a similar magnitude, i.e., (4 ± 1) × 10−3 K−1. The largest source of BVOC emissions in this region is broadleaf trees, thus if the observed temperature dependence of AOD is caused by biogenic emissions the dependence should be the largest in the vicinity of forests. Consequently, the analysis of the remote sensing data shows that over mixed forests the biogenic contribution increases AOD by approximately (27 ± 13) × 10−3 K−1, which is over four times higher than the value for over the whole domain, while over other land cover types in the study region (woody savannas and cropland/natural mosaic) there is no clear temperature dependence. The corresponding clear-sky direct radiative effect (DRE) of the observation-based biogenic AOD is −0.33 ± 0.29 W/m2/K for the whole domain and −1.3 ± 0.7 W/m2/K over mixed forests only. The model estimate of the regional clear-sky DRE for biogenic aerosols is similar to the observational estimate for the whole domain: −0.29 ± 0.09 W/m2/K. Furthermore, the model simulations showed that biogenic emissions have a significant effective radiative forcing (ERF) in this region: −1.0 ± 0.5 W/m2/K. [ABSTRACT FROM AUTHOR]

The chemistry-climate model ECHAMHAMMOZ contains a detailed representation of tropospheric and stratospheric reactive chemistry and state-of-the-art parameterizations of aerosols using either a modal scheme (M7) or a bin scheme (SALSA). This article describes and evaluates the model version ECHAM6.3-HAM2.3-MOZ1.0 with a focus on the tropospheric gas-phase chemistry. A 10-year model simulation was performed to test the stability of the model and provide data for its evaluation. The comparison to observations concentrates on the year 2008 and includes total column observations of ozone and CO from IASI and OMI, Aura MLS observations of temperature, HNO3, ClO, and O3 for the evaluation of polar stratospheric processes, an ozonesonde climatology, surface ozone observations from the TOAR database, and surface CO data from the Global Atmosphere Watch network. Global budgets of ozone, OH, NOx, aerosols, clouds, and radiation are analyzed and compared to the literature. ECHAMHAMMOZ performs well in many aspects. However, in the base simulation, lightning NOx emissions are very low, and the impact of the heterogeneous reaction of HNO3 on dust and sea salt aerosol is too strong. Sensitivity simulations with increased lightning NOx or modified heterogeneous chemistry deteriorate the comparison with observations and yield excessively large ozone budget terms and too much OH. We hypothesize that this is an impact of potential issues with tropical convection in the ECHAM model. [ABSTRACT FROM AUTHOR]

The chemistry climate model ECHAM-HAMMOZ contains a detailed representation of tropospheric and stratospheric reactive chemistry and state-of-the-art parametrisations of aerorols using either a modal scheme (M7) or a bin scheme (SALSA). This article describes and evaluates the model version ECHAM6.3-HAM2.3-MOZ1.0 with a focus on the tropospheric gas-phase chemistry. A ten-year model simulation was performed to test the stability of the model and provide data for its evaluation. The comparison to observations concentrates on the year 2008 and includes total column observations of ozone (O3) and carbon monoxide (CO) from Infrared Atmospheric Sounding Interferometer (IASI) and Ozone Monitoring Instrument (OMI), Microwave Limb Sounder (MLS) observations of temperature, nitric acid (HNO3), chlorine monoxide (ClO), and O3 for the evaluation of polar stratospheric processes, an ozone sonde climatology, surface ozone observations from the Tropospheric Ozone Assessment Report (TOAR) database, and surface CO data from the Global Atmosphere Watch network. Global budgets of ozone, hydroxide (OH), nitrogen oxides (NOx), aerosols, clouds, and radiation are analyzed and compared to the literature. ECHAM-HAMMOZ performs well in many aspects. However, in the base simulation, lightning NOx emissions are very low, and the impact of the heterogeneous reaction of HNO3 on dust and seasalt aerosol is too strong. Sensitivity simulations with increased lightning NOx or modified heterogeneous chemistry deteriorate the comparison with observations and yield excessively large ozone budget terms and too much OH. We hypothesize that this is an impact of potential issues with tropical convection in the ECHAM model. [ABSTRACT FROM AUTHOR]

Challenges in understanding the aerosol–cloud interactions and their impacts on global climate highlight the need for improved knowledge of the underlying physical processes and feedbacks as well as their interactions with cloud and boundary layer dynamics. To pursue this goal, increasingly sophisticated cloud-scale models are needed to complement the limited supply of observations of the interactions between aerosols and clouds. For this purpose, a new large-eddy simulation (LES) model, coupled with an interactive sectional description for aerosols and clouds, is introduced. The new model builds and extends upon the well-characterized UCLA Large-Eddy Simulation Code (UCLALES) and the Sectional Aerosol module for Large-Scale Applications (SALSA), hereafter denoted as UCLALES-SALSA. Novel strategies for the aerosol, cloud and precipitation bin discretisation are presented. These enable tracking the effects of cloud processing and wet scavenging on the aerosol size distribution as accurately as possible, while keeping the computational cost of the model as low as possible. The model is tested with two different simulation set-ups: a marine stratocumulus case in the DYCOMS-II campaign and another case focusing on the formation and evolution of a nocturnal radiation fog. It is shown that, in both cases, the size-resolved interactions between aerosols and clouds have a critical influence on the dynamics of the boundary layer. The results demonstrate the importance of accurately representing the wet scavenging of aerosol in the model. Specifically, in a case with marine stratocumulus, precipitation and the subsequent removal of cloud activating particles lead to thinning of the cloud deck and the formation of a decoupled boundary layer structure. In radiation fog, the growth and sedimentation of droplets strongly affect their radiative properties, which in turn drive new droplet formation. The size-resolved diagnostics provided by the model enable investigations of these issues with high detail. It is also shown that the results remain consistent with UCLALES (without SALSA) in cases where the dominating physical processes remain well represented by both models. [ABSTRACT FROM AUTHOR]

From macroscopic to microscopic scales it is demonstrated that diffusion through membranes can be modeled using specific boundary conditions across them. The membranes are here considered thin in comparison to the overall size of the system. In a macroscopic scale the membrane is introduced as a transmission boundary condition, which enables an effective modeling of systems that involve multiple scales. In a mesoscopic scale, a numerical lattice-Boltzmann scheme with a partial-bounceback condition at the membrane is proposed and analyzed. It is shown that this mesoscopic approach provides a consistent approximation of the transmission boundary condition. Furthermore, analysis of the mesoscopic scheme gives rise to an expression for the permeability of a thin membrane as a function of a mesoscopic transmission parameter. In a microscopic model, the mean waiting time for a passage of a particle through the membrane is in accordance with this permeability. Numerical results computed with the mesoscopic scheme are then compared successfully with analytical solutions derived in a macroscopic scale, and the membrane model introduced here is used to simulate diffusive transport between the cell nucleus and cytoplasm through the nuclear envelope in a realistic cell model based on fluorescence microscopy data. By comparing the simulated fluorophore transport to the experimental one, we determine the permeability of the nuclear envelope of HeLa cells to enhanced yellow fluorescent protein. [ABSTRACT FROM AUTHOR]

Aerosol-cloud interactions and their impacts of global climate highlight the need for improved knowledge of the underlying physical processes and feedbacks as well as their interactions with cloud and boundary-layer dynamics. To pursue this goal, more sophisticated cloud-scale models are needed to complement the limited supply of observations. For this purpose, a new large-eddy simulation model, coupled with an interactive sectional description for aerosols and clouds, is introduced. The model, UCLALES-SALSA, builds and extends upon a well characterized LES model and microphysical model components. Novel strategies for the aerosol, cloud and drizzle bin layouts are presented. These enable tracking the effects of cloud processing and wet scavenging on the aerosol size distribution as accurately as possible while keeping the computational cost of the model acceptable. The model is tested with two different cases: one comprising a case with marine stratocumulus and another focusing on the formation and evolution of a nocturnal radiation fog. It is shown that the size-resolved interactions between aerosols and clouds have a critical influence on the dynamics of the boundary layer in both cases. The results demonstrate the importance of accurately representing the wet scavenging of aerosols in the model. Specifically, in a case with marine stratocumulus, drizzle formation and the subsequent removal of cloud activating particles lead to thinning of the cloud deck and the formation of a decoupled boundary layer structure. In radiation fogs the growth and sedimentation of droplets strongly affects their radiative properties, which in turn drive new droplet formation. The size resolved diagnostics provided by the model enable investigations of these issues with high detail. It is also shown that the results remain consistent with an earlier version of the UCLALES model in cases, where the dominating physical processes remain well represented by both. [ABSTRACT FROM AUTHOR]

Objective: It was the aim of our study to evaluate the independent effect of preterm prelabor rupture of membranes (PPROM) as a cause of preterm delivery on mortality during primary hospital stay and significant morbidities in very-low-birth-weight (VLBW) infants < 32 weeks of gestation. Design: Observational, epidemiological study design. Setting: Population-based cohort, German Neonatal Network (GNN). Population: 6102 VLBW infants were enrolled in GNN from 2009-2012, n=4120 fulfilled criteria for primary analysis (< 32 gestational weeks, no pre-eclampsia, HELLP (highly elevated liver enzymes and low platelets syndrome) or placental abruption as cause of preterm birth). Methods: Multivariable logistic regression analyses included PPROM as potential risk factors for adverse outcomes and well established items such as gestational age in weeks, birth weight, antenatal steroids, center, inborn delivery, multiple birth, gender and being small-for-gestational-age. Results: PPROM as cause of preterm delivery had no independent effect on the risk of early-onset sepsis, clinical sepsis and blood-culture proven sepsis, while gestational age proved to be the most important contributor to sepsis risk. The diagnosis of PPROM was associated with an increased risk for bronchopulmonary dysplasia (BPD; OR: 1.25, 95% CI: 1.02-1.55, p=0.03) but not with other major outcomes. Conclusions: The diagnosis of PPROM per se is not associated with adverse outcome in VLBW infants < 32 weeks apart from a moderately increased risk for BPD. Randomized controlled trials with primary neonatal outcomes are needed to determine which subgroup of VLBW infants benefit from expectant or intentional management of PPROM. [ABSTRACT FROM AUTHOR]

The effects of aerosol on cloud droplet effective radius (Reff), cloud optical thickness and cloud droplet number concentration (Nd) are analysed both from long-term direct ground-based in situ measurements conducted at the Puijo measurement station in Eastern Finland and from the Moderate Resolution Imaging Spectroradiometer (MODIS) instrument onboard the Terra and Aqua satellites. The mean in situ Nd during the period of study was 217 cm-3, while the MODIS-based Nd was 171 cm-3. The absolute values, and the dependence of both Nd observations on the measured aerosol number concentration in the accumulation mode (Nacc), are quite similar. In both data sets Nd is clearly dependent on Nacc, for Nacc values lower than approximately 450 cm-3. Also, the values of the aerosol-cloud-interaction parameter [ACI=(1/3)*d ln(Nd)/d ln(Nacc)] are quite similar for Nacc<400 cm-3 with values of 0.16 and 0.14 from in situ and MODIS measurements, respectively. With higher Nacc (>450 cm-3) Nd increases only slowly. Similarly, the effect of aerosol on MODIS-retrieved Reff is visible only at low Nacc values. In a sub set of data, the cloud and aerosol properties were measured simultaneously. For that data the comparison between MODIS-derived Nd and directly measured Nd, or the cloud droplet number concentration estimated from Nacc values (Nd,p), shows a correlation, which is greatly improved after careful screening using a ceilometer to make sure that only single cloud layers existed. This suggests that such determination of the number of cloud layers is very important when trying to match ground-based measurements to MODIS measurements. [ABSTRACT FROM AUTHOR]

The effect of K fertilization on microstructural soil stability is rarely analyzed until now although the ambiguous impact on bulk soil structure was reported quite often, e.g., with regard to higher erodibility on the one hand and higher water storage on the other. Soil material from different long-term fertilization trials in Germany was examined rheologically by means of an amplitude sweep test where the samples were subjected to oscillating shearing with increasing deflection. The resulting shear stress was recorded, and the maximum stress denoted the maximum shear strength of the sample. Results showed an ambiguous influence of K which depends strongly on the soil properties. On the one hand, an increased ion concentration in the soil solution leads to increasing attractive forces as defined by the DLVO theory and therefore higher shear resistance. With increasing desiccation, K+ like other salts can precipitate at the contact areas between particles and lead to cementation. On the other hand, K+ as a monovalent ion impedes covalent and ionic bonding between clay minerals which holds true for most of the examined soil types while only sandy soils showed an increase in soil strength due to K fertilization. Potassium depletion further resulted in increased interaction of fertilization with other impact factors, e.g., climate and soil properties. Thus, the destabilizing effect of K+ was more pronounced under liming as without liming. Subsequent modeling with selected soil parameters confirmed the high influence of matric potential. The modeling also revealed the interactions with other soil parameters, e.g., pH, oxides, texture, exchangeable cations as well as lack or surplus of K in relation to recommended K content. In conclusion, microstructural stability of soil depends on several soil parameters and requires the inclusion of many chemical and physical soil properties. [ABSTRACT FROM AUTHOR]