Recent laboratory experiments indicate that destructive collisions of icy dust particles occur with much lower velocities than previously thought. These fragmentation velocities play a crucial role ...in planet formation because they set the maximum grain size in collisional growth models. When these new velocities are considered from laboratory experiments in dust evolution models, a growth to pebble sizes (typically millimeter- to decimeter-sized particles) in protoplanetary disks is difficult. This may contradict (sub-) millimeter observations and challenge the formation of planetesimals and planets. We investigate the conditions that are required in dust evolution models for growing and trapping pebbles in protoplanetary disks when the fragmentation speed is 1 m s
−1
in the entire disk. In particular, we distinguish the parameters controlling the effects of turbulent velocities (
δ
t
), vertical stirring (
δ
z
), radial diffusion (
δ
r
), and gas viscous evolution (
α
), always assuming that particles cannot diffuse faster (radially or vertically) than the gas (i.e.,
δ
r,z,t
≤
α
). We compare our models with observations of protoplanetary disks at both the near-infrared and millimeter regimes. To form pebbles and produce effective particle trapping, the parameter that controls the particle turbulent velocities must be small (
δ
t
≲ 10
−4
). In these cases, the vertical settling can limit the formation of pebbles, which also prevents particle trapping. Therefore the parameter that sets the vertical settling and stirring of the grains must be
δ
z
< 10
−3
. Our results suggest that different combinations of the particle and gas diffusion parameters can lead to a large diversity of millimeter fluxes and dust-disk radii. When pebble formation occurs and trapping is efficient, gaps and rings have higher contrast at millimeter emission than in the near-infrared. In the case of inefficient trapping, structures are also formed at the two wavelengths, producing deeper and wider gaps in the near-infrared. Our results highlight the importance of obtaining observational constraints of gas and particle diffusion parameters and the properties of gaps at short and long wavelengths to better understand basic features of protoplanetary disks and the origin of the structures that are observed in these objects.
Climate change is likely to have altered the ecological functioning of past ecosystems, and is likely to alter functioning in the future; however, the magnitude and direction of such changes are ...difficult to predict. Here we use a deep-time case study to evaluate the impact of a well-constrained CO
-induced global warming event on the ecological functioning of dominant plant communities. We use leaf mass per area (LMA), a widely used trait in modern plant ecology, to infer the palaeoecological strategy of fossil plant taxa. We show that palaeo-LMA can be inferred from fossil leaf cuticles based on a tight relationship between LMA and cuticle thickness observed among extant gymnosperms. Application of this new palaeo-LMA proxy to fossil gymnosperms from East Greenland reveals significant shifts in the dominant ecological strategies of vegetation found across the Triassic-Jurassic transition. Late Triassic forests, dominated by low-LMA taxa with inferred high transpiration rates and short leaf lifespans, were replaced in the Early Jurassic by forests dominated by high-LMA taxa that were likely to have slower metabolic rates. We suggest that extreme CO
-induced global warming selected for taxa with high LMA associated with a stress-tolerant strategy and that adaptive plasticity in leaf functional traits such as LMA contributed to post-warming ecological success.
Premature failure of timber construction can have dramatic consequences, at worst threat to human life or physical condition. Timber components might perform unexpectedly poor due to insufficient ...protection by misuse, design, low work execution level, or due to low resistance of the material in use. However, information about the material resistance of prematurely failed structures is usually lacking. Therefore this study aimed on developing a method to display the relationship between damages occurring on structures in service and the resistance against wood-destroying fungi of the material used.
Drilling cores taken from wooden structures were found to have the ability to serve as specimens in laboratory decay test when compared to standard specimens. Therefore, drilling cores were sampled from different components of six timber bridges in Hannover, Germany, made from English oak (Quercus robur L.). The cores were submitted to the white rot fungus Trametes versicolor and to soft rot fungi in terrestrial microcosms. The determined mass losses due to fungal decay were compared with the level of damage of the studied bridge components. The results indicated that the material-inherent resistance was responsible for damages rather than poor details of the construction. The methodological approach might be used to provide further knowledge about the relationship of timber in service and under ideal laboratory test conditions.
► Drilling core samples from oak timber bridges were tested against decay fungi. ► Wood resistance determined in the lab was compared with in-service performance. ► Results indicated that the material-inherent resistance was responsible for damages. ► Methodological approach useful to increase knowledge about reasons for premature failure.
Following a patient complaint, the Health Department carried out a hygiene inspection of a urological practice in Braunschweig in February 2013. The topic of the complaint was that a patient assumed ...having acquired a resistant pathogen in the practice. In the subsequent visit, significant hygiene defects were found, particularly with regard to the processing of medical devices. This led to a decision to commit all urological practices in Braunschweig to hygiene inspections as part of a priority project. In retrospect, the hygiene surveys were justified. Deficiencies included inadequate preparation of medical products, procedures in practice inconsistent with hygiene plans, poor knowledge of hygiene procedures among assistant staff and doctors, lack of expertise of assistant staff and lack of hygiene risk awareness by doctors. Positive experiences were: open communication in a good atmosphere with the Practice managers, willingness to change, good cooperation between the Health Authority and the Labor Inspectorate and Physicians' Association. The claimed deficits were corrected by spring 2014 by the practice operators. The consulting expertise of the health authorities was made use of continuously.
Summary
Background A reduction of symptoms of atopic dermatitis (AD) in small infants by the administration of Lactobacillus rhamnosus has been reported in a few studies. One study with older ...children and adolescents failed to show any effect.
Objectives We conducted a prospective study to reassess the efficacy of orally administered L. rhamnosus strain GG (LGG) in infants with AD.
Methods In a randomized, double‐blind, placebo‐controlled study, 54 infants aged 1–55 months with moderate to severe AD were randomized to daily 10 × 109 colony‐forming units of LGG or to placebo during an 8‐week intervention phase. Emollients, class I–II topical corticosteroids and antihistamines were permitted.
Results The treatment with LGG was well tolerated. At the end of treatment there were no significant differences between the groups with respect to clinical symptoms (SCORAD, pruritus, sleep loss), the use of topical corticosteroids and antihistamines, immunological parameters, or health‐related quality of life of the parents.
Conclusions Our results could not confirm LGG as an effective treatment of AD in infancy.
Jet substructure observables and properties of jet fragmentation are sensitive to a wide range of Quantum Chromo-dynamics (QCD) phenomena. They are essential to probe a new regime of QCD at hadron ...colliders. Measurements of jet substructure observables are also crucial to improve our understanding of the jet substructure properties used in many searches for physics beyond the Standard Model (BSM). These proceedings present some measurements of jet substructure and jet fragmentation observables performed with 33 fb−1 of proton-proton (pp) collision data collected by the ATLAS experiment at the Large Hadron Collider (LHC) at centre-of-mass energy of s=13 TeV The measurements are corrected for detector effects, represented as particle-level distributions and are compared with state-of-the-art Monte Carlo (MC) simulations and theoretical calculations.
To investigate and disentangle the role of major histocompatibility complex (MHC)‐based ‘good genes' and ‘compatible genes' in mate choice, three‐spined sticklebacks Gasterosteus aculeatus with ...specific MHC IIB genotypes were allowed to reproduce in an outdoor enclosure system. Here, fish were protected from predators but encountered their natural parasites. Mate choice for an intermediate genetic distance between parental MHC genotypes was observed, which would result in intermediate diversity in the offspring, but no mate choice based on good genes was found under the current semi‐natural conditions. Investigation of immunological variables revealed that the less‐specific innate immune system was more active in individuals with a genetically more divergent MHC allele repertoire. This suggests the need to compensate for an MHC‐diminished T‐cell repertoire and potentially explains the observed mate choice for intermediate MHC genetic distance. The present findings support a general pattern of mate choice for intermediate MHC diversity (i.e. compatible genes). In addition, the potentially dynamic role of MHC good genes in mate choice under different parasite pressures is discussed in the light of present and previous results.
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