Freeform terahertz structures fabricated by multi-photon lithography and metal coating

Direct-write multi-photon laser lithography (MPL) combines highest resolution on the nanoscale with essentially unlimited 3D design freedom. Over the previous years, the groundbreaking potential of this technique has been demonstrated in various application fields, including micromechanics, material sciences, microfluidics, life sciences as well as photonics, where in-situ printed optical coupling elements offer new perspectives for package-level system integration. However, millimeter-wave (mmW) and terahertz (THz) devices could not yet leverage the unique strengths of MPL, even though the underlying devices and structures could also greatly benefit from 3D freeform microfabrication. One of the key challenges in this context is the fact that functional mmW and THz structures require materials with high electrical conductivity and low dielectric losses, which are not amenable to structuring by multi-photon polymerization. In this work, we introduce and experimentally demonstrate a novel approach that allows to leverage MPL for fabricating high-performance mmW and THz structures with hitherto unachieved functionalities. Our concept exploits in-situ printed polymer templates that are selectively coated through highly directive metal deposition techniques in combination with precisely aligned 3D-printed shadowing structures. The resulting metal-coated freeform structures offer high surface quality in combination with low dielectric losses and conductivities comparable to bulk material values, while lending themselves to fabrication on planar mmW/THz circuits. We experimentally show the viability of our concept by demonstrating a series of functional THz structures such as THz interconnects, probe tips, and suspended antennas. We believe that our approach offers disruptive potential in the field of mmW and THz technology and may unlock an entirely new realm of laser-based 3D manufacturing

One academic year under COVID-19 conditions: two multicenter cross-sectional evaluation studies among medical students in Bavarian medical schools, Germany students’ needs, difficulties, and concerns about digital teaching and learning

BACKGROUND: Since March 2020, COVID-19 has created a need for adaptation in many areas of life. This study explores medical students’ perspectives on digital teaching under conditions of the COVID-19 pandemic. It focuses on expectations and concerns about digital teaching, the evaluation of specific aspects of teaching, and requests for future teaching. METHODS: Six German faculties have joined forces within the Bavarian network for medical education to develop and deploy a common core questionnaire. Cross-sectional surveys were conducted at the end of the summer semester 2020 and winter semester 2020/21. Medical students from different semesters participated in the online survey. Data was analyzed descriptively and/or inferentially. Item differences across semesters were examined using contingency tables and Chi(2) tests. Mean values were compared using the independent samples t-test; answer frequencies in retrospective and prospective concerns were compared using contingency tables and Chi(2) tests with Yates’ correction. RESULTS: In the summer semester 2020, 1565 students and in winter semester 2020/21, 1727 students took part in the survey. Students’ main prospective concern was lack of social exchange between fellow students (70%), but also with teachers. Second and third most often concerns were a lack of practical training (68%) and lack of integration of on-site digital teaching (50%). Approximately 7% of the students lacked sufficient access to technical equipment.. Approximately 39% of the students lacked a sufficient internet connection for synchronous digital teaching, 17% for asynchronous digital teaching. On-site teaching was the preferred form of teaching (60%), and there was a preference for asynchronous (24%) over synchronous (15%) digital teaching. Teaching recordings (79%) were particularly popular to complement future on-site teaching. CONCLUSIONS: The following areas of education under COVID-19 conditions are highly important to medical students: adequacy of information sharing, integration of opportunities for exchange with fellow students and teachers, possibility to perform practical trainings. After the normalization of the pandemic situation, on-site teaching should be supplemented with blended learning concepts such as the inverted classroom model. GRAPHICAL ABSTRACT: Percentages of results are rounded averages from summer and winter semesters. [Image: see text] SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12909-022-03480-x

Dynamics on expanding spaces: modeling the emergence of novelties

Novelties are part of our daily lives. We constantly adopt new technologies, conceive new ideas, meet new people, experiment with new situations. Occasionally, we as individuals, in a complicated cognitive and sometimes fortuitous process, come up with something that is not only new to us, but to our entire society so that what is a personal novelty can turn into an innovation at a global level. Innovations occur throughout social, biological and technological systems and, though we perceive them as a very natural ingredient of our human experience, little is known about the processes determining their emergence. Still the statistical occurrence of innovations shows striking regularities that represent a starting point to get a deeper insight in the whole phenomenology. This paper represents a small step in that direction, focusing on reviewing the scientific attempts to effectively model the emergence of the new and its regularities, with an emphasis on more recent contributions: from the plain Simon's model tracing back to the 1950s, to the newest model of Polya's urn with triggering of one novelty by another. What seems to be key in the successful modelling schemes proposed so far is the idea of looking at evolution as a path in a complex space, physical, conceptual, biological, technological, whose structure and topology get continuously reshaped and expanded by the occurrence of the new. Mathematically it is very interesting to look at the consequences of the interplay between the "actual" and the "possible" and this is the aim of this short review.Comment: 25 pages, 10 figure

Synthesis and (spectro)electrochemistry of mixedvalent diferrocenyl–dihydrothiopyran derivatives

Three novel diferrocenyl complexes were prepared and characterised. 2,2-Diferrocenyl-4,5-dimethyl- 3,6-dihydro-2H-thiopyran (1, sulphide) was accessible by the hetero-Diels–Alder reaction of diferrocenyl thioketone with 2,3-dimethyl-1,3-butadiene. Stepwise oxidation of 1 gave the respective oxides 2,2- diferrocenyl-4,5-dimethyl-3,6-dihydro-2H-thiopyran-1-oxide (2, sulfoxide) and 2,2-diferrocenyl-4,5- dimethyl-3,6-dihydro-2H-thiopyran-1,1-dioxide (3, sulfone), respectively. The molecular structures of 1 and 3 in the solid state were determined by single crystal X-ray crystallography. The oxidation of sulphide 1 to sulfone 3, plays only a minor role on the overall structure of the two compounds. Electrochemical (cyclic voltammetry (= CV), square wave voltammetry (= SWV)) and spectroelectrochemical (in situ UV-Vis/NIR spectroscopy) studies were carried out. The CV and SWV measurements showed that an increase of the sulphur atom oxidation from −2 in 1 to +2 in 3 causes an anodic shift of the ferrocenylbased oxidation potentials of about 100 mV. The electrochemical oxidation of 1–3 generates mixedvalent cations 1+–3+. These monooxidised species display low-energy electronic absorption bands between 1000 and 3000 nm assigned to IVCT (= Inter-Valence Charge Transfer) electronic transitions. Accordingly, the mixed-valent cations 1+–3+ are classified as weakly coupled class II systems according to Robin and Day.Authors (K. K. and G. M.) thank the National Science Centre (Poland) for financial support (Project Maestro-3; Dec-2012/06/ A/ST5/00219) and R. C. thanks the German Federal Ministry of Education and Research (BMBF) for support. The support from the German Academic Exchange Service (DAAD) in the framework of the exchange program “Ostpartnerschaften” is highly appreciated

Multivariate moments expansion density: application of the dynamic equicorrelation model

In this study, we propose a new semi-nonparametric (SNP) density model for describing the density of portfolio returns. This distribution, which we refer to as the multivariate moments expansion (MME), admits any non-Gaussian (multivariate) distribution as its basis because it is specified directly in terms of the basis density’s moments. To obtain the expansion of the Gaussian density, the MME is a reformulation of the multivariate Gram-Charlier (MGC), but the MME is much simpler and tractable than the MGC when positive transformations are used to produce well-defined densities. As an empirical application, we extend the dynamic conditional equicorrelation (DECO) model to an SNP framework using the MME. The resulting model is parameterized in a feasible manner to admit two-stage consistent estimation and it represents the DECO as well as the salient non-Gaussian features of portfolio return distributions. The in- and out-of-sample performance of a MME-DECO model of a portfolio of 10 assets demonstrate that it can be a useful tool for risk management purposes

Silver activation on thin films of Ag-ZrCN coatings for antimicrobial activity

Nowadays, with the increase of elderly population and related health problems, knee and hip joint prosthesis are being widely used worldwide. However, failure of these invasive devices occurs in a high percentage thus demanding the revision of the chirurgical procedure. Within the reasons of failure, microbial infections, either hospital or subsequently-acquired, contribute in high number to the statistics. Staphylococcus epidermidis (S. epidermidis) has emerged as one of the major nosocomial pathogens associated with these infections. Silver has a historic performance in medicine due to its potent antimicrobial activity, with a broad-spectrum on the activity of different types of microorganisms. Consequently, the main goal of this work was to produce Ag-ZrCN coatings with antimicrobial activity, for the surface modification of hip prostheses. Thin films of ZrCN with several silver concentrations were deposited onto stainless steel 316 L, by DC reactive magnetron sputtering, using two targets, Zr and Zr with silver pellets (Zr + Ag target), in an atmosphere containing Ar, C2H2 and N2. The antimicrobial activity of the modified surfaces was tested against S. epidermidis and the influence of an activation step of silver was assessed by testing samples after immersion in a 5 % (w/v) NaClO solution for 5 minutes. The activation procedure revealed to be essential for the antimicrobial activity, as observed by the presence of an inhibition halo on the surface with 11 at. % of Ag. The morphology analysis of the surface before and after the activation procedure revealed differences in silver distribution indicating segregation/diffusion of the metallic element to the films surface. Thus, the results indicate that the silver activation step is responsible for an antimicrobial effect of the coatings, due to silver oxidation and silver ion release.IF acknowledges the financial support of FCT-Fundacao para a Ciencia e a Tecnologia through grant SFRH/BD/71139/2010.This research is partially sponsored by FEDER funds through the program COMPETE-Programa Operacional Factores de Competitividade and by Portuguese national funds through FCT-Fundacao para a Ciencia e a Tecnologia, under the projects ANTIMICROBCOAT-PTDC/CTM/102853/2008 and in the framework of the Strategic Projects PEST-C/FIS/UI607/2011, and PEST-C/EME/UI0285/2011.The authors thank the FCT Strategic Project PEST-OE/EQB/LA0023/2013 and the Project "BioHealth-Biotechnology and Bioengineering approaches to improve health quality", Ref. NORTE-07-0124-FEDER-000027, co-funded by the Programa Operacional Regional do Norte (ON.2 - O Novo Norte), QREN, FEDER. The authors also acknowledge the project "Consolidating Research Expertise and Resources on Cellular and Molecular Biotechnology at CEB/IBB", Ref. FCOMP-01-0124-FEDER-027462

EFEKTIFITAS JARINGAN PERJALANAN DENGAN MENGGUNAKAN TEORI GRAF HAMILTON (STUDI KASUS SIMPANG LIMA-TERMINAL BATOH, BANDA ACEH)

Terminal adalah suatu prasarana transportasi jalan untuk menurunkan dan menaikkan penumpang, yang mengatur kedatangan dan pemberangkatan kendaraan umum. Memperbanyak jaringan jalan dan membuatnya terintegrasi juga merupakan salah satu pertimbangan yang membuat perjalanan menjadi lebih efisien dan lebih efektif, sehingga diperoleh penghematan waktu tempuh dalam pergerakan trayek angkutan umum penumpang dan barang. Berdasarkan latar belakang yang telah dipaparkan di atas, maka dilakukan studi yang bertujuan untuk menentukan jalur terbaik berdasarkan waktu dan rute terpendek dalam sistem jaringan jalan dari Simpang Lima menuju Terminal Batoh Kota Banda Aceh dengan tiga rute alternatif. Pengumpulan data jarak tempuh dan waktu tempuh perjalanan, dilakukan pada jaringan jalan tersebut dengan menggunakan odometer dan stopwatch. Data tersebut kemudian dilakukan perhitungan dengan bantuan Microsoft Excel. Pemodelan menggunakan metode Graf, kemudian dilakukan analisis siklus Hamilton. Hasil yang diperoleh dari perhitungan analisis interaksi kegiatan jaringan pergerakan adalah apabila rute 1 yang beroperasi, maka jumlah pergerakan lalu lintas yang terjadi, yaitu sebesar 5.219 kendaraan/jam dengan waktu tempuh 23,67 menit. Apabila rute 2 yang beroperasi, maka jumlah pergerakan lalu lintas yang terjadi, yaitu sebesar 4.240 kendaraan/jam dengan waktu tempuh 29,14 menit. Apabila rute 3 yang beroperasi, maka jumlah pergerakan lalu lintas yang terjadi, yaitu sebesar 5.598 kendaraan/jam dengan waktu tempuh 22,07 menit. Apabila rute 1 dan rute 2 sama-sama beroperasi, maka jumlah total pergerakan lalu lintas adalah 6.795 kendaraan/jam dengan waktu tempuh 18,18 menit. Apabila rute 1, 2 dan 3 sama-sama beroperasi, maka jumlah total pergerakan lalu lintas adalah 43.895 kendaraan/jam dengan waktu tempuh 2,81 menit. Maka rute kombinasi 1, 2 dan 3 yang efektifitas beroperasi sekaligus, karena semakin banyak pilihan rute atau alternatif jaringan, maka semakin besar pergerakan yang dapat dilakukan dan waktu tempuh yang dihasilkan semakin kecil. Kata kunci: pemilihan jalur alternatif, rute efektif, metode graf hamilton.Banda Ace

Inequalities, harm reduction and non-combustible nicotine products:A meta-ethnography of qualitative evidence

BACKGROUND: We sought to review qualitative evidence on how smokers in different socioeconomic groups engage with non-combustible nicotine products (NCNP), including electronic cigarettes and nicotine replacement therapies, in order to provide insight into how these products might impact on smoking inequalities. METHODS: We searched ten electronic databases in February 2017 using terms relating to NCNP and socioeconomic status. We included qualitative studies that were published since 1980 and were available in English. We used guidelines adapted from the Critical Appraisal Skills Programme for appraising qualitative research. RESULTS: The review only identified studies exploring the attitudes of socioeconomically disadvantaged smokers towards NCNP for harm reduction or cessation purposes (i.e. we did not identify any relevant studies of more advantaged socioeconomic groups). Using a lines-of-argument meta-ethnographic approach, we identified a predominantly pessimistic attitude to NCNP for harm reduction or cessation of smoking due to: wider circumstances of socioeconomic disadvantage; lack of a perceived advantage of alternative products over smoking; and a perceived lack of information about relative harms of NCNP compared to smoking. Optimistic findings, although fewer, suggested the potential of NCNP being taken up among smokers experiencing socioeconomic disadvantage. CONCLUSIONS: Overall, our review highlights the importance of considering the social, cultural and economic circumstances that influence experiences of smoking and of alternative product use

NR4A orphan nuclear receptor family members, NR4A2 and NR4A3, regulate neutrophil number and survival.

Neutrophil lifespan is plastic and highly responsive to factors that regulate cellular survival. Defects in neutrophil number and survival are common to both hematologic disorders and chronic inflammatory diseases. At sites of inflammation, neutrophils respond to multiple signals that activate protein kinase A (PKA) signaling, which positively regulates neutrophil survival. The aim of this study was to define transcriptional responses to PKA activation and to delineate the roles of these factors in neutrophil function and survival. In human neutrophil gene array studies, we show that PKA activation upregulates a significant number of apoptosis related genes, the most highly regulated of these being NR4A2 and NR4A3 Direct PKA activation by the site-selective PKA agonist pair N6/8-AHA and treatment with endogenous activators of PKA, including adenosine and PGE2, results in a profound delay of neutrophil apoptosis and concomitant upregulation of NR4A2/3 in a PKA dependent manner. NR4A3 expression is also increased at sites of neutrophilic inflammation in a human model of intradermal inflammation. PKA activation also promotes survival of murine neutrophil progenitor cells, and siRNA to NR4A2 decreases neutrophil production in this model. Antisense knockdown of NR4A2 and NR4A3 homologues in zebrafish larvae significantly reduces absolute neutrophil number without affecting cellular migration. In summary, we show that NR4A2 and NR4A3 are components of a downstream transcriptional response to PKA activation in the neutrophil, and that they positively regulate neutrophil survival and homeostasis