Interaction of atomic systems with quantum vacuum beyond electric dipole approximation

The photonic environment can significantly influence emission properties and interactions among atomic systems. In such scenarios, frequently the electric dipole approximation is assumed that is justified as long as the spatial extent of the atomic system is negligible compared to the spatial variations of the field. While this holds true for many canonical systems, it ceases to be applicable for more contemporary nanophotonic structures. To go beyond the electric dipole approximation, we propose and develop in this article an analytical framework to describe the impact of the photonic environment on emission and interaction properties of atomic systems beyond the electric dipole approximation. Particularly, we retain explicitly magnetic dipolar and electric quadrupolar contributions to the light-matter interactions. We exploit a field quantization scheme based on electromagnetic Green’s tensors, suited for dispersive materials. We obtain expressions for spontaneous emission rate, Lamb shift, multipole-multipole shift and superradiance rate, all being modified with dispersive environment. The considered influence could be substantial for suitably tailored nanostructured photonic environments, as demonstrated exemplarily

Controlling statistical properties of stored light

Statistical properties of outgoing light pulses are studies after they have been stored in a medium of atoms in the tripod configuration. A generalized Hong-Ou-Mandel interference, storing of squeezed states and homodyne signal analysis are discussed in the context of their dependence on the parameters of the control fields used for light storage and release.Comment: 5 figure

Energy-Based Plasmonicity Index to Characterize Optical Resonances in Nanostructures

Resonances sustained by plasmonic nanoparticles provide extreme electric field confinement and enhancement into the deep subwavelength domain for a plethora of applications. Recent progress in nanofabrication made it even possible to tailor the properties of nanoparticles consisting of only a few hundred atoms. These nanoparticles support both single-particle-like resonances and collective plasmonic charge density oscillations. Prototypical systems sustaining both features are graphene nanoantennas. In pushing the frontier of nanoscience, traditional identification, and classification of such resonances is at stake again. We show that in such nanostructures, the concerted electron cloud oscillation in real space does not necessarily come along with collective dynamics of conduction band electrons in energy space. This unveils an urgent need for a discussion of how a plasmon in nanostructures should be defined. Here, we propose to define it relying on energy space dynamics. The unambiguous identification of the plasmonic nature of a resonance is crucial to find out whether desirable plasmon-assisted features, such as frequency conversion processes, can be expected from a resonance. We elaborate an energy-based figure of merit that classifies the nature of resonances in nanostructures, motivated by tight binding simulations with a toy model consisting of a linear chain of atoms. We apply afterward the proposed figure of merit to a doped hexagonal graphene nanoantenna, which is known to support plasmons in the near infrared and single-particle-like transitions in the visible

Genetic variation at 16q24.2 is associated with small vessel stroke.

OBJECTIVE: Genome-wide association studies (GWAS) have been successful at identifying associations with stroke and stroke subtypes, but have not yet identified any associations solely with small vessel stroke (SVS). SVS comprises one quarter of all ischemic stroke and is a major manifestation of cerebral small vessel disease, the primary cause of vascular cognitive impairment. Studies across neurological traits have shown that younger-onset cases have an increased genetic burden. We leveraged this increased genetic burden by performing an age-at-onset informed GWAS meta-analysis, including a large younger-onset SVS population, to identify novel associations with stroke. METHODS: We used a three-stage age-at-onset informed GWAS to identify novel genetic variants associated with stroke. On identifying a novel locus associated with SVS, we assessed its influence on other small vessel disease phenotypes, as well as on messenger RNA (mRNA) expression of nearby genes, and on DNA methylation of nearby CpG sites in whole blood and in the fetal brain. RESULTS: We identified an association with SVS in 4,203 cases and 50,728 controls on chromosome 16q24.2 (odds ratio [OR; 95% confidence interval {CI}] = 1.16 [1.10-1.22]; p = 3.2 × 10-9 ). The lead single-nucleotide polymorphism (rs12445022) was also associated with cerebral white matter hyperintensities (OR [95% CI] = 1.10 [1.05-1.16]; p = 5.3 × 10-5 ; N = 3,670), but not intracerebral hemorrhage (OR [95% CI] = 0.97 [0.84-1.12]; p = 0.71; 1,545 cases, 1,481 controls). rs12445022 is associated with mRNA expression of ZCCHC14 in arterial tissues (p = 9.4 × 10-7 ) and DNA methylation at probe cg16596957 in whole blood (p = 5.3 × 10-6 ). INTERPRETATION: 16q24.2 is associated with SVS. Associations of the locus with expression of ZCCHC14 and DNA methylation suggest the locus acts through changes to regulatory elements. Ann Neurol 2017;81:383-394.Matthew Traylor is funded by the NIHR Biomedical Research Centre based at Guy's and St Thomas' NHS Foundation Trust and King's College London. Hugh Markus is supported by an NIHR Senior Investigator award and his work is supported by NIHR Comprehensive Biomedical Research Unit funding awarded to Cambridge University Hospitals Trust. Cathryn Lewis receives salary support from the National Institute for Health Research (NIHR) Mental Health Biomedical Research Centre at South London and Maudsley NHS Foundation Trust and King’s College London. Collection of the UK Young Lacunar Stroke DNA Study (DNA Lacunar) was primarily supported by the Wellcome Trust (WT072952) with additional support from the Stroke Association (TSA 2010/01). Genotyping of the DNA Lacunar samples was supported by a Stroke Association Grant (TSA 2013/01). Robin Lemmens is a senior clinical investigator of FWO Flanders. Martin Dichgans received funding from the DFG (CRC 1123, B3) and a EU Horizon 2020 grant (agreement No 666881 SVDs@target). The TwinsUK study was funded in part by the European Research Council (ERC 250157), and from the TwinsUK resource, which receives support from the Wellcome Trust and the National Institute for Health Research (NIHR)-funded BioResource, Clinical Research Facility and Biomedical Research Centre based at Guy's and St Thomas' NHS Foundation Trust in partnership with King's College London. SNP Genotyping was performed by The Wellcome Trust Sanger Institute and National Eye Institute via NIH/CIDR. The SiGN study was funded by a cooperative agreement grant from the US National Institute of Neurological Disorders and Stroke, National Institutes of Health (U01 NS069208)

The determination of normal stresses in cross-section of the four-flue reinforced concrete chimney

W niniejszej pracy zaprezentowano analityczny sposób wyznaczenia naprężeń w kominie czteroprzewodowym o przekroju złożonym z wycinków pierścieni. Przeanalizowano cztery modele obliczeniowe komina: układ przewodów pełny i z otworami ustawiony na kształt rombu w stosunku do przepływu wiatru oraz układ przewodów pełny i z otworami ustawiony na kształt kwadratu w stosunku do przepływu wiatru. Przy wykonywaniu obliczeń wykorzystano prace M. Lachmana [1] i [2], w których podane są dane wyjściowe do obliczeń kominów wieloprzewodowych.In the paper the way of calculation of compressive stresses in the cross-section of a four-flue reinforced concrete chimney has been presented. Two types of cross section have been considered: the full cross section and the cross section weakened by openings. The analysis described in the paper refers to the chimney arrangement in diamond shape in relation to wind flow

Naziemna organizacja ruchu czy kładki i przejścia podziemne dla pieszych w miastach?

Przechodzenie pieszych przez drogę należy do najbardziej ryzykownych zachowań uczestników ruchu. Ponieważ miasta charakteryzują się dużym udziałem ruchu pieszych, organizacja ich ruchu, obok zapewnienia jak najlepszej przepustowości, to jedno z najważniejszych zadań, jakie stoi przed projektantem dróg i ulic oraz zarządzającym ruchem. Rozwiązaniem gwarantującym największy poziom bezpieczeństwa dla pieszych oraz przepustowość drogi jest kładka lub przejście podziemne, lecz wiążą się one jednocześnie z największymi kosztami, zarówno na etapie budowy, jak i utrzymania. Naziemna organizacja ruchu wymaga także znacznych nakładów finansowych, szczególnie przy bardziej rozbudowanych przejściach przez jezdnię. W referacie opisano uwarunkowania bezpiecznego ruchu pieszych na przejściach jednopoziomowych oraz wielopoziomowych. Dokonano analizy alternatywnych rozwiązań przejść dla pieszych na trzech przykładach związanych z różnymi aspektami realizacji dwupoziomowych przejść dla pieszych. Przedstawione w referacie przykłady pokazują, jak wiele czynników wpływa na wybór między przejściem naziemnym a kładką lub tunelem dla pieszych. Rozstrzygnięcie o priorytecie jednego z czynników: wygody pieszych, przystosowania do potrzeb wszystkich użytkowników, przepustowości drogi oraz kosztów nie jest jednoznaczne i powinno być każdorazowo poprzedzone wnikliwą analizą, już na etapie podjęcia decyzji o budowie przejścia wielopoziomowego.Crossing the street is the most risky action for pedestrians. Because of significant pedestrian traffic in the cities, its organization, besides ensuring the best traffic capacity, is one of the most important tasks for roads and streets designer and traffic administrator. A solution that guarantees the highest level of safety and proper road traffic capacity is a footbridge or an underpass, but they are the most expensive solutions at the same time, both during the construction stage and in maintenance. Ground traffic organization requires also high financial expenditures, especially in case of larger crossings. In the paper the authors described conditions for a safe pedestrian traffic on singlelevel and two-level pedestrian crossings. An alternative solution analysis is presented on three examples connected with diffrent aspects of two-level crossing construction. The examples show how many factors have to be concidered when choosing between ground traffic organization or footbridges and underpasses for pedestrians. Deciding on a priority of one of the factors: pedestrians convenience, adaptation for the needs of all of the users, road traffic capacity and costs is not simple and should be supported each time with a careful analysis from the very beginning

Dimensioning of reinforced concrete multi - flue chimneys

W artykule opisano zagadnienia związane z projektowaniem żelbetowych kominów przemysłowych wieloprzewodowych o złożonych kształcie przekroju, które nie są ujęte w przepisach normowych. Dokonano również przeglądu różnych koncepcji kształtowania przekroju kominów wieloprzewodowych, ze szczególnym uwzględnieniem kominów trzy i czteroprzewodowych. Artykuł jest wzbogacony o przykłady żelbetowych kominów tego typu zrealizowanych w Polsce.In the paper there are presented the basic principles of dimensioning of reinforced concrete multi-flue industrial chimneys. The calculation problems appear when the cross section is more complicated than simple annular one, for which there are rules in the code. Different concepts of multi-flue chimneys, especially three-flue and four-flue chimneys, are described and the examples of industrial chimneys built in Poland are given as well

Porównanie testów Proctora i jednoosiowego ściskania dla wybranych gleb

The objective of this paper was to compare the results of soil material compaction carried out with the use of the Proctor and uniaxial compression tests in order to find relations between these methods. Soil material in the form of loose mass was collected from the layer deposited at the depth from 35 to 60 cm in order to determine its typical properties (textural group, density of solid particles, humus content, reaction, plastic and liquid limits) and in order to compact it in the Proctor apparatus and in the uniaxial compression test. Results of both tests were used for construction of regression models reflecting the course of the unit stress (Pρdp), necessary to generate compaction equal to the dry density of solid particles obtained in the Proctor apparatus (ρdp) in relation to the sample moisture (ws). It was stated that the stress value Pρdp on the soil sample in the uniaxial compression test depends significantly on ws. It was proved that for the purpose of comparing the results of both tests, the uniaxial stress of samples must be performed in conditions of their lateral expansion. It was also proved that the use of the uniaxial test with possible lateral expansion of soil with a model sample, a diameter of which is 100 and the height is 30 mm, one may determine the obtained compaction with the use of the plate movement value.Celem pracy było porównanie rezultatów zagęszczania materiału glebowego prowadzonego za pomocą testów Proctora i jednoosiowego ściskania, ukierunkowane na poszukiwanie zależności pomiędzy tymi metodami. Z warstwy leżącej na głębokości od 35 do 60 cm pobrano materiał glebowy w postaci luźnej masy celem oznaczenia jego typowych cech własnych (skład granulometryczny, gęstość fazy stałej, zawartość próchnicy, odczyn, granice plastyczności i płynności) i przeprowadzenia jego zagęszczania w aparacie Proctora oraz w teście jednoosiowego ściskania. Wyniki obu testów wykorzystano do budowy modeli regresji odwzorowujących przebieg nacisku jednostkowego (Pρdp), niezbędnego do wytworzenia zagęszczenia równoważnego gęstości objętościowej uzyskiwanej w aparacie Proctora (ρdp), w zależności od wilgotności próbki (ws). Stwierdzono, że wartość nacisku Pρdp wywieranego na próbkę gleby w teście jednoosiowego ściskania zależy istotnie od ws. Wykazano, że do celów porównywania wyników obu testów jednoosiowe odkształcanie próbek należy wykonywać w warunkach możliwej ich bocznej rozszerzalności. Wykazano także, że stosując test jednoosiowy z możliwą boczną rozszerzalnością gleby, z zastosowaniem próbek modelowych o średnicy 100 i wysokości 30 mm, można do określenia uzyskiwanego zagęszczenia wykorzystać wartość przemieszczenia stempla