Mesophase formation in two-component cylindrical bottle-brush polymers

When two types of side chains (A,B) are densely grafted to a (stiff) backbone and the resulting bottle-brush polymer is in a solution under poor solvent conditions, an incompatibility between A and B leads to microphase separation in the resulting cylindrical brush. The possible types of ordering are reminiscent of the ordering of block copolymers in cylindrical confinement. Starting from this analogy, Leibler's theory of microphase separation in block copolymer melts is generalized to derive a description of the system in the weak segregation limit. Also molecular dynamics simulation results of a corresponding coarse-grained bead-spring model are presented. Using side chain lengths up to N = 50 effective monomers, the ratio of the Lennard-Jones energy parameter between unlike monomers $(\epsilon_{AB})$ and monomers of the same kind $(\epsilon _{AA} = \epsilon_{BB})$ is varied. Various correlation functions are analyzed to study the conditions when (local) Janus cylinder-type ordering and when (local) microphase separation in the direction along the cylinder axis occurs. Both the analytical theory and the simulations give evidence for short range order due to a tendency towards microphase separation in the axial direction, with a wavelength proportional to the side chain gyration radius, irrespective of temperature and grafting density, for a wide range of these parameters.Comment: 26 pages, 19 figure

Better Operating Room Ventilation as Determined by a Novel Ventilation Index is Associated with Lower Rates of Surgical Site Infections.

OBJECTIVE To assess the impact of operating room (OR) ventilation quality on surgical site infections (SSI) using a novel ventilation index. SUMMARY BACKGROUND DATA Previous studies compared laminar air flow with conventional ventilation, thereby ignoring many parameters that influence air flow properties. METHODS In this cohort study, we surveyed hospitals participating in the Swiss SSI surveillance and calculated a ventilation index for their ORs, with higher values reflecting less turbulent air displacement. For procedures captured between 01/2017-12/2019, we studied the association between ventilation index and SSI rates using linear regression (hospital-level analysis) and with the individual SSI risk using generalized linear mixed-effects models (patient-level analysis). RESULTS We included 47 hospitals (182 ORs). Among the 163'740 included procedures, 6791 SSIs were identified. In hospital-level analyses, a 5-unit increase in the ventilation index was associated with lower SSI rates for knee and hip arthroplasty (-0.41 infections per 100 procedures, CI -0.69 to -0.13), cardiac (-0.89, -1.91 to 0.12), and spine surgeries (-1.15, -2.56 to 0.26). Similarly, patient-level analyses showed a lower SSI risk with each 5-unit increase in ventilation index (adjusted odds ratio 0.71, CI 0.58 to 0.87 for knee and hip; 0.72, 0.49 to 1.06 for spine; 0.82, 0.69 to 0.98 for cardiac surgery). Higher index values were mainly associated with a lower risk for superficial and deep incisional SSIs. CONCLUSIONS Better ventilation properties, assessed with our ventilation index, are associated with lower rates of superficial and deep incisional SSIs in orthopedic and cardiac procedures. OR ventilation quality appeared to be less relevant for other surgery types

Better operating room ventilation as determined by a novel ventilation index is associated with lower rates of surgical site infections

OBJECTIVE: The aim was to assess the impact of operating room (OR) ventilation quality on surgical site infections (SSIs) using a novel ventilation index. BACKGROUND: Previous studies compared laminar air flow with conventional ventilation, thereby ignoring many parameters that influence air flow properties. METHODS: In this cohort study, we surveyed hospitals participating in the Swiss SSI surveillance and calculated a ventilation index for their ORs, with higher values reflecting less turbulent air displacement. For procedures captured between January 2017 and December 2019, we studied the association between ventilation index and SSI rates using linear regression (hospital-level analysis) and with the individual SSI risk using generalized linear mixed-effects models (patient-level analysis). RESULTS: We included 47 hospitals (182 ORs). Among the 163,740 included procedures, 6791 SSIs were identified. In hospital-level analyses, a 5-unit increase in the ventilation index was associated with lower SSI rates for knee and hip arthroplasty (-0.41 infections per 100 procedures, 95% confidence interval: -0.69 to -0.13), cardiac (-0.89, -1.91 to 0.12), and spine surgeries (-1.15, -2.56 to 0.26). Similarly, patient-level analyses showed a lower SSI risk with each 5-unit increase in ventilation index (adjusted odds ratio 0.71, confidence interval: 0.58-0.87 for knee and hip; 0.72, 0.49-1.06 for spine; 0.82, 0.69-0.98 for cardiac surgery). Higher index values were mainly associated with a lower risk for superficial and deep incisional SSIs. CONCLUSIONS: Better ventilation properties, assessed with our ventilation index, are associated with lower rates of superficial and deep incisional SSIs in orthopedic and cardiac procedures. OR ventilation quality appeared to be less relevant for other surgery types

Epilepsy, hippocampal sclerosis and febrile seizures linked by common genetic variation around SCN1A

Epilepsy comprises several syndromes, amongst the most common being mesial temporal lobe epilepsy with hippocampal sclerosis. Seizures in mesial temporal lobe epilepsy with hippocampal sclerosis are typically drug-resistant, and mesial temporal lobe epilepsy with hippocampal sclerosis is frequently associated with important co-morbidities, mandating the search for better understanding and treatment. The cause of mesial temporal lobe epilepsy with hippocampal sclerosis is unknown, but there is an association with childhood febrile seizures. Several rarer epilepsies featuring febrile seizures are caused by mutations in SCN1A, which encodes a brain-expressed sodium channel subunit targeted by many anti-epileptic drugs. We undertook a genome-wide association study in 1018 people with mesial temporal lobe epilepsy with hippocampal sclerosis and 7552 control subjects, with validation in an independent sample set comprising 959 people with mesial temporal lobe epilepsy with hippocampal sclerosis and 3591 control subjects. To dissect out variants related to a history of febrile seizures, we tested cases with mesial temporal lobe epilepsy with hippocampal sclerosis with (overall n = 757) and without (overall n = 803) a history of febrile seizures. Meta-analysis revealed a genome-wide significant association for mesial temporal lobe epilepsy with hippocampal sclerosis with febrile seizures at the sodium channel gene cluster on chromosome 2q24.3 [rs7587026, within an intron of the SCN1A gene, P = 3.36 × 10−9, odds ratio (A) = 1.42, 95% confidence interval: 1.26-1.59]. In a cohort of 172 individuals with febrile seizures, who did not develop epilepsy during prospective follow-up to age 13 years, and 6456 controls, no association was found for rs7587026 and febrile seizures. These findings suggest SCN1A involvement in a common epilepsy syndrome, give new direction to biological understanding of mesial temporal lobe epilepsy with hippocampal sclerosis with febrile seizures, and open avenues for investigation of prognostic factors and possible prevention of epilepsy in some children with febrile seizure

Search for dark matter produced in association with bottom or top quarks in √s = 13 TeV pp collisions with the ATLAS detector

A search for weakly interacting massive particle dark matter produced in association with bottom or top quarks is presented. Final states containing third-generation quarks and miss- ing transverse momentum are considered. The analysis uses 36.1 fb−1 of proton–proton collision data recorded by the ATLAS experiment at √s = 13 TeV in 2015 and 2016. No significant excess of events above the estimated backgrounds is observed. The results are in- terpreted in the framework of simplified models of spin-0 dark-matter mediators. For colour- neutral spin-0 mediators produced in association with top quarks and decaying into a pair of dark-matter particles, mediator masses below 50 GeV are excluded assuming a dark-matter candidate mass of 1 GeV and unitary couplings. For scalar and pseudoscalar mediators produced in association with bottom quarks, the search sets limits on the production cross- section of 300 times the predicted rate for mediators with masses between 10 and 50 GeV and assuming a dark-matter mass of 1 GeV and unitary coupling. Constraints on colour- charged scalar simplified models are also presented. Assuming a dark-matter particle mass of 35 GeV, mediator particles with mass below 1.1 TeV are excluded for couplings yielding a dark-matter relic density consistent with measurements

Finishing the euchromatic sequence of the human genome

The sequence of the human genome encodes the genetic instructions for human physiology, as well as rich information about human evolution. In 2001, the International Human Genome Sequencing Consortium reported a draft sequence of the euchromatic portion of the human genome. Since then, the international collaboration has worked to convert this draft into a genome sequence with high accuracy and nearly complete coverage. Here, we report the result of this finishing process. The current genome sequence (Build 35) contains 2.85 billion nucleotides interrupted by only 341 gaps. It covers ∼99% of the euchromatic genome and is accurate to an error rate of ∼1 event per 100,000 bases. Many of the remaining euchromatic gaps are associated with segmental duplications and will require focused work with new methods. The near-complete sequence, the first for a vertebrate, greatly improves the precision of biological analyses of the human genome including studies of gene number, birth and death. Notably, the human enome seems to encode only 20,000-25,000 protein-coding genes. The genome sequence reported here should serve as a firm foundation for biomedical research in the decades ahead

Dust in Supernovae and Supernova Remnants II: Processing and survival

Observations have recently shown that supernovae are efficient dust factories, as predicted for a long time by theoretical models. The rapid evolution of their stellar progenitors combined with their efficiency in precipitating refractory elements from the gas phase into dust grains make supernovae the major potential suppliers of dust in the early Universe, where more conventional sources like Asymptotic Giant Branch (AGB) stars did not have time to evolve. However, dust yields inferred from observations of young supernovae or derived from models do not reflect the net amount of supernova-condensed dust able to be expelled from the remnants and reach the interstellar medium. The cavity where the dust is formed and initially resides is crossed by the high velocity reverse shock which is generated by the pressure of the circumstellar material shocked by the expanding supernova blast wave. Depending on grain composition and initial size, processing by the reverse shock may lead to substantial dust erosion and even complete destruction. The goal of this review is to present the state of the art about processing and survival of dust inside supernova remnants, in terms of theoretical modelling and comparison to observations

Faust im Studierzimmer / Kurt Hildebrand

FAUST IM STUDIERZIMMER / KURT HILDEBRAND Faust im Studierzimmer / Kurt Hildebrand (1) Faust im Studierzimmer (1