Plasmonic photoconductive terahertz focal-plane array with pixel super-resolution

Imaging systems operating in the terahertz part of the electromagnetic spectrum are in great demand because of the distinct characteristics of terahertz waves in penetrating many optically-opaque materials and providing unique spectral signatures of various chemicals. However, the use of terahertz imagers in real-world applications has been limited by the slow speed, large size, high cost, and complexity of the existing imaging systems. These limitations are mainly imposed due to the lack of terahertz focal-plane arrays (THz-FPAs) that can directly provide the frequency-resolved and/or time-resolved spatial information of the imaged objects. Here, we report the first THz-FPA that can directly provide the spatial amplitude and phase distributions, along with the ultrafast temporal and spectral information of an imaged object. It consists of a two-dimensional array of ~0.3 million plasmonic photoconductive nanoantennas optimized to rapidly detect broadband terahertz radiation with a high signal-to-noise ratio. As the first proof-of-concept, we utilized the multispectral nature of the amplitude and phase data captured by these plasmonic nanoantennas to realize pixel super-resolution imaging of objects. We successfully imaged and super-resolved etched patterns in a silicon substrate and reconstructed both the shape and depth of these structures with an effective number of pixels that exceeds 1-kilo pixels. By eliminating the need for raster scanning and spatial terahertz modulation, our THz-FPA offers more than a 1000-fold increase in the imaging speed compared to the state-of-the-art. Beyond this proof-of-concept super-resolution demonstration, the unique capabilities enabled by our plasmonic photoconductive THz-FPA offer transformative advances in a broad range of applications that use hyperspectral and three-dimensional terahertz images of objects for a wide range of applications.Comment: 62 page

Implementation of Optimal Thermal Radiation Pumps Using Adiabatically Modulated Photonic Cavities

We numerically implement the concept of thermal radiation pumps in realistic photonic circuits and demonstrate their efficiency to control the radiation current, emitted between two reservoirs with equal temperature. The proposed pumping scheme involves a cyclic adiabatic modulation of two parameters that control the spectral characteristics of the photonic circuit. We show that the resulting pumping cycle exhibits maximum radiation current when a cyclic modulation of the system is properly engineered to be in the proximity of a resonance degeneracy in the parameter space of the photonic circuit. A developed Floquet scattering framework, which in the adiabatic limit boils down to the analysis of an instantaneous scattering matrix, is offering an engineering tool for designing and predicting the performance of such thermal pumps. Our predictions are confirmed by time-domain simulations invoking an adiabatically driven photonic cavity.Fil: Fernández, Lucas Jonatan. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Instituto de Modelado e Innovación Tecnológica. Universidad Nacional del Nordeste. Facultad de Ciencias Exactas Naturales y Agrimensura. Instituto de Modelado e Innovación Tecnológica; ArgentinaFil: Li, Huanan. City University of New York; Estados UnidosFil: Nafari, Mona. Wesleyan University; Estados UnidosFil: Kottos, Tsampikos. Wesleyan University; Estados Unido

Teachers’ Perceptions of Good and Bad Leaders in Seven Cultures

Educational practices are becoming increasingly globalized, and as a result, countries around the world are implementing reforms along the lines of American and European practices, although the cultural implications of these changes are not always being fully realized. Only recently have educational thinkers begun to address cultural issues in educational leadership

Zeitersparnis vs. Adhäsion : Haben Inkrementstärke und Konditionierungsverfahren einen signifikanten Einfluss auf die Dentinhaftung eines Ultrakurzzeitpolymerisats?

Hintergrund und Ziele In der Füllungstherapie mit lichthärtenden Kompositen stellt die ausreichende Polymerisati-on einen wichtigen Faktor für die Langlebigkeit einer indirekten Restauration da. Eine mini-male Belichtungszeit von mindestens 20 s pro Fläche, sollte dabei mit einem herkömmlichen Polymerisationsgerät nicht unterschritten werden. Neue Technologien, die hochintensive Lichthärtung in 3 s versprechen, sind aus klinischer Sicht durch ihre Zeitersparnis bei der Behandlung attraktiv. Diese Studie vergleicht die Wirkung von hochintensiver (3 s mit 3.500 mW/cm2) und konventioneller (20 s mit 1.480 mW/cm2) Lichthärtung auf den Dentinverbund, bei unterschiedlicher Inkrementstärke und Schmelz-Dentin-Konditionierung von konventio-nellen Nano-Hybrid- und Bulk-Fill-Kompositen, einschließlich zweier Ultrakurzeit-polymerisate, die speziell für die hochintensive Härtung entwickelt wurden. Material und Methode Diese Studie wurde an 50 menschlichen dritten Molaren, die frei von Karies und Schmelz- oder Dentin-Anomalien waren und aus therapeutischen Gründen extrahiert wurden, in vitro durchgeführt. In alle Zähne wurde eine Klasse I Kavität mit den Maßen 4 mm x 4 mm x 4 mm gebohrt. Im Anschluss wurden alle Zähne in acht Gruppen (n=5) eingeteilt und abhängig ihrer Versuchsgruppeneinteilung mit dem Etch-Rinse oder Selective-Enamel-Etch-Verfahren geätzt und mit einem lichthärtenden Ein-Schritt-Adhäsiv AdheSE Universal, welches Teil des 3s-PowerCure-Produktsystems (Fa. Ivoclar Vivcadent, Schann, Lichtenstein) ist, gebon-det. Vier Gruppen wurden im nächsten Schritt mit lichthärtenden stopf- und fließfähigen Bulk-Fill-Kompositen desselben Produktsystems, in Inkrement oder Bulk-Fill-Technik, gefüllt und mit der dazugehörigen Hochleistungspolymerisationslampe 3s-PowerCure-Bluephase im 3s-Cure-Modus ausgehärtet. Weitere vier Gruppen wurden als Vergleichswert mit dem her-kömmlichen Nano-Hybrid Komposit Venus Pearl (Fa. Heraeus Kulzer GmbH + Co. KG, Hanau, Deutschland) oder dem Bulk-Fill-Flowable SDR (Fa. Densply Sirona, Konstanz, Deutschland), ebenfalls in Inkrement oder Bulk-Fill-Technik, gefüllt und mit einer herkömmlichen Poly-merisationslampe Elipar LED (3M ESPE, Seefeld, Deutschland) 20 s ausgehärtet. Anschlie-ßend wurden die Proben in Stäbchen gesägt und der Haftverbund zwischen Dentin und Kom-posit mit der Mikrotensile gemessen und ausgewertet. Ergebnisse und Beobachtungen In allen Gruppen erhöhte die Inkrementschichtung die Dentinhaftung signifikant (ANOVA: F(1,81) = 7,45, p = 0,008, ƞ2 = 0,08). Bei der Anwendung von Ultrakurzeitpolymerisaten und dem Hochintensivpolymerisationsgerät, führte eine Selective-Enemal-Etch-Konditionierung, zu signifikant weniger vorzeitigen Brüchen (logistische Regression: B = 0,50, SE = 0,15, Wald = 11,77, p [ ,001, OR = 1,64). Es konnten keine signifikanten Unterschiede der Dentinhaftung für die beiden verglichenen Polymerisationssysteme festgestellt werden (ANOVA: F (1,81) = 0,57, p = 0,454, ƞ2 = 0,01). Praktische Schlussfolgerung Diese Studie ergab, dass die Inkrementschichtung auch bei Ultrakurzeitpolymerisaten der Bulkfill-Technik zu bevorzugen ist. Bei der Schmelzkonditionierung hingegen sollte eine reine Schmelzätzung der E+R-Technik bevorzugt werden. In Klasse I Kavitäten kann das getestete Ultrakurzzeitpolymerisat vergleichbare Haftwerte wie mit den Standard Kompositen erzie-len

p21-activated kinase-1 signaling regulates transcription of tissue factor and tissue factor pathway inhibitor.

Tissue factor (TF) is a cell-surface glycoprotein responsible for initiating the coagulation cascade. Besides its role in homeostasis, studies have shown the implication of TF in embryonic development, cancer related events, and inflammation via coagulation-dependent and -independent (signaling) mechanisms. Tissue factor pathway inhibitor (TFPI) plays an important role in regulating TF-initiated blood coagulation. Therefore, transcriptional regulation of TF expression and its physiologic inhibitor TFPI, would allow us to understand the critical step that control many different processes. From a gene profiling study aimed to identify differentially regulated genes between wild type (WT) and p21-activated kinase 1-null (PAK1-KO) mouse embryonic fibroblasts (MEFs), we found TF and TFPI are differentially expressed in the PAK1-KO MEFs in comparison to wild-type MEFs. Based on these findings, we further investigated in the present study the transcriptional regulation of TF and TFPI by PAK1, a serine/threonine kinase. We found that PAK1/c-Jun complex stimulates the transcription of TF and consequently, its procoagulant activity. Moreover, PAK1 negatively regulates the expression of TFPI and thus, additionally, contributes to increased TF activity. For the first time, this study implicates PAK1 in coagulation processes, through its dual transcriptional regulation of TF and its inhibitor

Effect of radiation interaction and aerosol processes on ventilation and aerosol concentrations in a real urban neighbourhood in Helsinki

Large-eddy simulation (LES) is an optimal tool to examine aerosol particle concentrations in detail within urban neighbourhoods. The concentrations are a complex result of local emissions, meteorology, aerosol processes and local mixing conditions due to thermal and mechanical effects. Despite this, most studies have focused on simplification of the affecting processes such as examining the impact of local mixing in idealised street canyons or treating aerosols as passive scalars. The aim of this study is to include all these processes into LES using the PALM model system and to examine the importance of radiative heating and aerosol processes in simulating local aerosol particle concentrations and different aerosol metrics within a realistic urban neighbourhood in Helsinki under morning rush hour with calm wind conditions. The model outputs are evaluated against mobile laboratory measurements of air temperature and total particle number concentration (Ntot) as well as drone measurements of lung-deposited surface area (LDSA). The inclusion of radiation interaction in LES has a significant impact on simulated near-surface temperatures in our study domain, increasing them on average from 8.6 to 12.4 ∘C. The resulting enhanced ventilation reduces the pedestrian-level (4 m) Ntot by 53 %. The reduction in Ntot due to aerosol processes is smaller, only 18 %. Aerosol processes particularly impact the smallest particle range, whereas radiation interaction is more important in the larger particle range. The inclusion of radiation interaction reduces the bias between the modelled and mobile-laboratory-measured air temperatures from −3.9 to +0.2 ∘C and Ntot from +98 % to −13 %. With both aerosol and radiation interaction on, the underestimation is 16 %, which might be due to overestimation of the ventilation. The results show how inclusion of radiative interaction is particularly important in simulating PM2.5, whereas aerosol processes are more important in simulating LDSA in this calm wind situation.</p