The study of the laws of nature has traditionally been pursued in the limit of isolated systems, where energy is conserved. This is not always a valid approximation, however, as the inclusion of ...features such as gain and loss, or periodic driving, qualitatively amends these laws. A contemporary frontier of metamaterial research is the challenge open systems pose to the characterization of topological matter1,2. Here, one of the most relied upon principles is the bulk–boundary correspondence (BBC), which intimately relates the surface states to the topological classification of the bulk3,4. The presence of gain and loss, in combination with the violation of reciprocity, has been predicted to affect this principle dramatically5,6. Here, we report the experimental observation of BBC violation in a non-reciprocal topolectric circuit7, which is also referred to as the non-Hermitian skin effect. The circuit admittance spectrum exhibits an unprecedented sensitivity to the presence of a boundary, displaying an extensive admittance mode localization despite a translationally invariant bulk. Intriguingly, we measure a non-local voltage response due to broken BBC. Depending on the a.c. current feed frequency, the voltage signal accumulates at the left or right boundary, and increases as a function of nodal distance to the current feed.Boundary-localized bulk eigenstates given by the non-Hermitian skin effect are observed in a non-reciprocal topological circuit. A fundamental revision of the bulk–boundary correspondence in an open system is required to understand the underlying physics.
Numerous environmental polycyclic aromatic hydrocarbon (PAH) sources have been reported in literature, however, unburnt hard coal/ bituminous coal is considered only rarely. It can carry native PAH ...concentrations up to hundreds, in some cases, thousands of mg/kg. The molecular structures of extractable compounds from hard coals consist mostly of 2–6 polyaromatic condensed rings, linked by ether or methylene bridges carrying methyl and phenol side chains. The extractable phase may be released to the aquatic environment, be available to organisms, and thus be an important PAH source. PAH concentrations and patterns in coals depend on the original organic matter type, as well as temperature and pressure conditions during coalification. The environmental impact of native unburnt coal-bound PAH in soils and sediments is not well studied, and an exact source apportionment is hardly possible. In this paper, we review the current state of the art.
Published literature has been reviewed in order to (a) explore the (potential) applications of nanotechnology in pesticide formulation, (b) identify possible impacts on environmental fate, and (c) ...analyze the suitability of current exposure assessment procedures to account for the novel properties of nanopesticides within the EU regulatory context. The term nanopesticide covers a wide variety of products and cannot be considered to represent a single category. Many nanoformulations combine several surfactants, polymers, and metal nanoparticles in the nanometer size range. The aims of nanoformulations are generally common to other pesticide formulations, these being to increase the apparent solubility of poorly soluble active ingredients, to release the active ingredient in a slow/targeted manner and/or to protect against premature degradation. Nanoformulations are thus expected to (a) have significant impacts on the fate of active ingredients and/or (b) introduce new ingredients for which the environmental fate is still poorly understood (e.g., nanosilver). Therefore, it seems that adaptations of current exposure assessment approaches will be necessary, at least for some nanopesticides. The present analysis provides a useful framework to identify priorities for future research in order to achieve more robust risk assessments of nanopesticides.
During the past two decades, density-functional (DF) theory has evolved from niche applications for simple solid-state materials to become a workhorse method for studying a wide range of phenomena in ...a variety of system classes throughout physics, chemistry, biology, and materials science. Here, we review the recent advances in DF calculations for materials modeling, giving a classification of modern DF-based methods when viewed from the materials modeling perspective. While progress has been very substantial, many challenges remain on the way to achieving consensus on a set of universally applicable DF-based methods for materials modeling. Hence, we focus on recent successes and remaining challenges in DF calculations for modeling hard solids, molecular and biological matter, low-dimensional materials, and hybrid organic-inorganic materials.
Most successful object recognition systems rely on binary classification, deciding only if an object is present or not, but not providing information on the actual object location. To estimate the ...object's location, one can take a sliding window approach, but this strongly increases the computational cost because the classifier or similarity function has to be evaluated over a large set of candidate subwindows. In this paper, we propose a simple yet powerful branch and bound scheme that allows efficient maximization of a large class of quality functions over all possible subimages. It converges to a globally optimal solution typically in linear or even sublinear time, in contrast to the quadratic scaling of exhaustive or sliding window search. We show how our method is applicable to different object detection and image retrieval scenarios. The achieved speedup allows the use of classifiers for localization that formerly were considered too slow for this task, such as SVMs with a spatial pyramid kernel or nearest-neighbor classifiers based on the lambda 2 distance. We demonstrate state-of-the-art localization performance of the resulting systems on the UIUC Cars data set, the PASCAL VOC 2006 data set, and in the PASCAL VOC 2007 competition.
The presence of dipolar layers determines the functionality of most technologically relevant interfaces. The present contribution reviews how periodic dipole assemblies modify the properties of such ...interfaces through so‐called collective electrostatic effects. They impact the ionization energies and electron affinities of thin films, change the work function of metallic and semiconducting substrates, and determine the alignment of electronic states at interfaces. Dipolar layers originate either from the assembly of polar molecules or they arise from interfacial charge rearrangements triggered by the deposition of an adsorbate layer. Such charge rearrangements result from the omnipresent Pauli pushback caused by exchange interaction, from covalent bonds, or from charge transfer following the deposition of particularly electron rich (donors) or electron poor molecules (acceptors). A peculiarity of charge‐transfer interfaces is that they enter the realm of Fermi‐level pinning, where the sample work function becomes independent of the substrate and is solely determined by the electronic properties of the adsorbate. Beyond changing work functions and injection barriers, the presence of polar layers also modifies various other physical observables, like core‐level binding energies or tunneling currents in monolayer junctions. All these aspects suggest that polar layers can also be exploited for electrostatically designing the electronic properties of materials.
Polar layers crucially impact the electronic properties of interfaces. In this article, their fundamental properties are reviewed, their physical origin is discussed and their impact on interfacial level alignment at metal/organic and semiconductor/organic interfaces is described. Emphasis is put on how they impact physical observables like work functions, core‐level energies, and transport properties and how they could be used for electrostatically designing materials.
The focus of the present article is on understanding the insight that X-ray photoelectron spectroscopy (XPS) measurements can provide when studying self-assembled monolayers. Comparing density ...functional theory calculations to experimental data on deliberately chosen model systems, we show that both the chemical environment and electrostatic effects arising from a superposition of molecular dipoles influence the measured core-level binding energies to a significant degree. The crucial role of the often overlooked electrostatic effects in polar self-assembled monolayers (SAMs) is unambiguously demonstrated by changing the dipole density through varying the SAM coverage. As a consequence of this effect, care has to be taken when extracting chemical information from the XP spectra of ordered organic adsorbate layers. Our results, furthermore, imply that XPS is a powerful tool for probing local variations in the electrostatic energy in nanoscopic systems, especially in SAMs.
Evasion of immune recognition by the innate and acquired immune system is a major principle of tumour cells and belongs to the hallmarks of cancer. Immune checkpoint inhibitor‐based cancer therapies ...targeting the co‐inhibitory receptors CTLA‐4 or PD‐1 have received enormous scientific and clinical attention during the last few years, because of promising clinical results observed in the treatment of different cancer entities including melanoma and cutaneous squamous cell carcinoma. However, the enthusiasm about the effects of the immune checkpoint inhibitors is muted as only a subfraction of patients shows a stable clinical response. To predefine the patient cohorts that may benefit from immune checkpoint therapy, rigorous biomarker analyses, which predict the response to these novel therapies, need to be performed. In addition, combination of immune checkpoint therapy with classical DNA‐damaging chemotherapy or radiotherapy, which positively affects tumour neo‐antigen presentation, appears to be a promising approach in optimizing patients’ response. In this review, we briefly summarize important biomarkers for patient stratification and discuss the current limitations of these biomarkers in defining responders vs. non‐responders to immune checkpoint therapy.
ObjectiveA systematic review and meta-analysis to investigate the efficacy of interventions incorporating motivational interviewing for smoking cessation and identify correlates of treatment ...effectsData sourcesMedline/PubMed, PsycInfo and other sources including grey literatureStudy selectionTitle/abstract search terms were motivational interview* OR motivational enhancement AND smok*, cigarette*, tobacco, OR nicotine. Randomised trials reporting number of smokers abstinent at follow up were eligible.Data extractionData were independently coded by the first and third authors. We coded for a variety of study, participant, and intervention related variables.Data synthesisA random effects logistic regression with both a random intercept and a random slope for the treatment effect.Results31 smoking cessation research trials were selected for the study: eight comprised adolescent samples, eight comprised adults with chronic physical or mental illness, five comprised pregnant/postpartum women and 10 comprised other adult samples. Analysis of the trials (9485 individual participants) showed an overall OR comparing likelihood of abstinence in the motivational interviewing (MI) versus control condition of OR 1.45 (95% CI 1.14 to 1.83). Additional potential correlates of treatment effects such as study, sample, and intervention characteristics were examined.ConclusionsThis is the most comprehensive review of MI for smoking cessation conducted to date. These findings suggest that current MI smoking cessation approaches can be effective for adolescents and adults. However, comparative efficacy trials could be useful.
Semilocal and hybrid density functional theory was used to study the charge transfer and the energy-level alignment at a representative interface between an extended metal substrate and an organic ...adsorbate layer. Upon suppressing electronic coupling between the adsorbate and the substrate by inserting thin, insulating layers of NaCl, the hybrid functional localizes charge. The laterally inhomogeneous charge distribution resulting from this spontaneous breaking of translational symmetry is reflected in observables such as the molecular geometry, the valence and core density of states, and the evolution of the work function with molecular coverage, which we discuss for different growth modes. We found that the amount of charge transfer is determined, to a significant extent, by the ratio of the lateral spacing of the molecules and their distance to the metal. Therefore, charge transfer does not only depend on the electronic structure of the individual components but, just as importantly, on the interface geometry.
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