Science and Technology Park of Crete

Abstract The rapid development of additive manufacturing has fueled a revolution in various research fields and industrial applications. Among the myriad of advanced 3D printing techniques, two‐photon polymerization lithography (TPL) uniquely offers a significant advantage in nanoscale print resolution, and has been widely employed in diverse fields, for example, life sciences, materials sciences, mechanics, and microfluidics. More recently, by virtue of the optical transparency of most of the resins used, TPL is finding new applications in optics and photonics, with nanometer to millimeter feature dimensions. It enables the minimization of optical elements and systems, and exploration of light‐matter interactions with new degrees of freedom, never possible before. To review the recent progress in the TPL related optical research, it starts with the fundamentals of TPL and material formulation, then discusses novel fabrication methods, and a wide range of optical applications. These applications notably include diffractive, topological, quantum, and color optics. With a panoramic view of the development, it is concluded with insights and perspectives of the future development of TPL and related potential optical applications.

Abstract A review on the recent development of intense laser‐driven terahertz (THz) sources is provided here. The technologies discussed include various types of sources based on optical rectification (OR), spintronic emitters, and laser‐filament‐induced plasma. The emphasis is on OR using pump pulses with tilted intensity front. Illustrative examples of newly emerging applications are briefly discussed, in particular strong‐field THz control of materials and acceleration and manipulation of charged particles.

ABSTRACT I evaluate the forced CEO turnover rate and quantify effects on shareholder value by estimating a dynamic model. The model features learning about CEO ability and costly turnover. To fit the observed forced turnover rate, the model needs the average board of directors to behave as if replacing the CEO costs shareholders at least $200 million. This cost mainly reflects CEO entrenchment rather than a real cost to shareholders. The model predicts that shareholder value would rise 3% if we eliminated this perceived turnover cost, all else equal. The model also helps explain the relation between CEO firings, tenure, and profitability.

Enteroviruses (EV) can cause severe neurological and respiratory infections, and occasionally lead to devastating outbreaks as previously demonstrated with EV-A71 and EV-D68 in Europe. However, these infections are still often underdiagnosed and EV typing data is not currently collected at European level. In order to improve EV diagnostics, collate data on severe EV infections and monitor the circulation of EV types, we have established European non-polio enterovirus network (ENPEN). First task of this cross-border network has been to ensure prompt and adequate diagnosis of these infections in Europe, and hence we present recommendations for non-polio EV detection and typing based on the consensus view of this multidisciplinary team including experts from over 20 European countries. We recommend that respiratory and stool samples in addition to cerebrospinal fluid (CSF) and blood samples are submitted for EV testing from patients with suspected neurological infections. This is vital since viruses like EV-D68 are rarely detectable in CSF or stool samples. Furthermore, reverse transcriptase PCR (RT-PCR) targeting the 5'noncoding regions (5'NCR) should be used for diagnosis of EVs due to their sensitivity, specificity and short turnaround time. Sequencing of the VP1 capsid protein gene is recommended for EV typing; EV typing cannot be based on the 5'NCR sequences due to frequent recombination events and should not rely on virus isolation. Effective and standardized laboratory diagnostics and characterisation of circulating virus strains are the first step towards effective and continuous surveillance activities, which in turn will be used to provide better estimation on EV disease burden.

The combination of materials with targeted optical properties and of complex, 3D architectures, which can be nowadays obtained by additive manufacturing, opens unprecedented opportunities for developing new integrated systems in photonics and optoelectronics. The recent progress in additive technologies for processing optical materials is here presented, with emphasis on accessible geometries, achievable spatial resolution, and requirements for printable optical materials. Relevant examples of photonic and optoelectronic devices fabricated by 3D printing are shown, which include light-emitting diodes, lasers, waveguides, optical sensors, photonic crystals and metamaterials, and micro-optical components. The potential of additive manufacturing applied to photonics and optoelectronics is enormous, and the field is still in its infancy. Future directions for research include the development of fully printable optical and architected materials, of effective and versatile platforms for multimaterial processing, and of high-throughput 3D printing technologies that can concomitantly reach high resolution and large working volumes.

With the advances in computer and networking technology, thousands of heterogeneous com-puters can be interconnected to provide a large collection of computing and communication resources. These systems are used by agrowing and increasingly heterogeneous set of users.

This paper presents a method for assigning the poles in a specified disk by state feedback for a linear discrete or continuous time uncertain system, the uncertainty being norm bounded. For this the "quadratic d stabilizability" concept which is the counterpart of quadratic stabilizability in the context of pole placement is defined and a necessary and sufficient condition for quadratic d stabilizability derived. This condition expressed as a parameter dependent discrete Riccati equation enables one to design the control gain matrix by solving iteratively a discrete Riccati equation.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

High mobility thin‐film transistor technologies that can be implemented using simple and inexpensive fabrication methods are in great demand because of their applicability in a wide range of emerging optoelectronics. Here, a novel concept of thin‐film transistors is reported that exploits the enhanced electron transport properties of low‐dimensional polycrystalline heterojunctions and quasi‐superlattices (QSLs) consisting of alternating layers of In 2 O 3 , Ga 2 O 3, and ZnO grown by sequential spin casting of different precursors in air at low temperatures (180–200 °C). Optimized prototype QSL transistors exhibit band‐like transport with electron mobilities approximately a tenfold greater (25–45 cm 2 V −1 s −1 ) than single oxide devices (typically 2–5 cm 2 V −1 s −1 ). Based on temperature‐dependent electron transport and capacitance‐voltage measurements, it is argued that the enhanced performance arises from the presence of quasi 2D electron gas‐like systems formed at the carefully engineered oxide heterointerfaces. The QSL transistor concept proposed here can in principle extend to a range of other oxide material systems and deposition methods (sputtering, atomic layer deposition, spray pyrolysis, roll‐to‐roll, etc.) and can be seen as an extremely promising technology for application in next‐generation large area optoelectronics such as ultrahigh definition optical displays and large‐area microelectronics where high performance is a key requirement.

Tunneling of electrons through a potential barrier is fundamental to chemical reactions, electronic transport in semiconductors and superconductors, magnetism, and devices such as terahertz oscillators. Whereas tunneling is typically controlled by electric fields, a completely different approach is to bind electrons into bosonic quasiparticles with a photonic component. Quasiparticles made of such light-matter microcavity polaritons have recently been demonstrated to Bose-condense into superfluids, whereas spatially separated Coulomb-bound electrons and holes possess strong dipole interactions. We use tunneling polaritons to connect these two realms, producing bosonic quasiparticles with static dipole moments. Our resulting three-state system yields dark polaritons analogous to those in atomic systems or optical waveguides, thereby offering new possibilities for electromagnetically induced transparency, room-temperature condensation, and adiabatic photon-to-electron transfer.

Abstract Here, a single‐step, biomimetic approach for the realization of omnidirectional transparent antireflective glass is reported. In particular, it is shown that circularly polarized ultrashort laser pulses produce self‐organized nanopillar structures on fused silica (SiO 2 ). The laser‐induced nanostructures are selectively textured on the glass surface in order to mimic the spatial randomness, pillar‐like morphology, as well as the remarkable antireflection properties found on the wings of the glasswing butterfly, Greta oto , and various Cicada species. The artificial structures exhibit impressive antireflective properties, both in the visible and infrared frequency ranges, which are remarkably stable over time. Accordingly, the laser‐processed glass surfaces show reflectivity smaller than 1% for various angles of incidence in the visible spectrum for s–p linearly polarized configurations. However, in the near‐infrared spectrum, the laser‐textured glass shows higher transmittance compared to the pristine. It is envisaged that the current results will revolutionize the technology of antireflective transparent surfaces and impact numerous applications from glass displays to optoelectronic devices.

The use of robots in waste processing plants can significantly improve the processing of recyclables. Such robots need sophisticated visual and manipulation skills to be able to work in the extremely heterogeneous, complex, and unpredictable waste sorting industrial environment. This article considers the implementation of an autonomous robotic system for the categorization and physical sorting of recyclables according to material types. In particular, it focuses on the development of a low-cost computer vision module based on deep learning technologies to identify and sort items. To facilitate further research endeavors, the data set of recyclable images and a group of image processing scripts for object identification, masking, and synthetic placement against multiple backgrounds are available in an open source GitHub repository (https://github.com/kskmar/ReSort-IT.git). The deep-trained computer vision module is integrated with a robotic system that undertakes the physical separation of recyclables. The composite system is deployed in a waste processing plant, where it is successfully assessed in recyclable sorting under difficult and demanding industrial conditions.

Catalysts for the photogeneration of hydrogen from water are key for realizing solar energy conversion. Despite tremendous efforts, developing hydrogen evolution catalysts with high activity and long‐term stability remains a daunting challenge. Herein, the design and fabrication of mesoporous Pt‐decorated CdS nanocrystal assemblies (NCAs) are reported, and their excellent performance for the photocatalytic hydrogen production is demonstrated. These materials comprise varying particle size of Pt (ranging from 1.8 to 3.3 nm) and exhibit 3D nanoscale pore structure within the assembled network. Photocatalytic measurements coupled with UV–vis/NIR optical absorption, photoluminescence, and electrochemical impedance spectroscopy studies suggest that the performance enhancement of these catalytic systems arises from the efficient hole transport at the CdS/electrolyte interface and interparticle Pt/CdS electron‐transfer process as a result of the deposition of Pt. It is found that the Pt‐CdS NCAs catalyst at 5 wt% Pt loading content exerts a 1.2 mmol h −1 H 2 ‐evolution rate under visible‐light irradiation (λ ≥ 420 nm) with an apparent quantum yield of over 70% at wavelength λ = 420 nm in alkaline solution (5 m NaOH), using ethanol (10% v/v) as sacrificial agent. This activity far exceeds those of the single CdS and binary noble metal/CdS systems, demonstrating the potential for practical photocatalytic hydrogen production.

SecA, the dimeric ATPase subunit of bacterial protein translocase, catalyses translocation during ATP-driven membrane cycling at SecYEG. We now show that the SecA protomer comprises two structural modules: the ATPase N-domain, containing the nucleotide binding sites NBD1 and NBD2, and the regulatory C-domain. The C-domain binds to the N-domain in each protomer and to the C-domain of another protomer to form SecA dimers. NBD1 is sufficient for single rounds of SecA ATP hydrolysis. Multiple ATP turnovers at NBD1 require both the NBD2 site acting in cis and a conserved C-domain sequence operating in trans. This intramolecular regulator of ATP hydrolysis (IRA) mediates N-/C-domain binding and acts as a molecular switch: it suppresses ATP hydrolysis in cytoplasmic SecA while it releases hydrolysis in SecY-bound SecA during translocation. We propose that the IRA switch couples ATP binding and hydrolysis to SecA membrane insertion/deinsertion and substrate translocation by controlling nucleotide-regulated relative motions between the N-domain and the C-domain. The IRA switch is a novel essential component of the protein translocation catalytic pathway.

hypocotyl growth, we found that cellulose synthesis and cell expansion can be uncoupled and are regulated by different mechanisms. We grew Arabidopsis plants in very short photoperiods and used a combination of extended nights, continuous light, sucrose feeding experiments, and photosynthesis inhibition to tease apart the influences of light, metabolic, and circadian clock signaling on rates of cellulose biosynthesis and cell wall biomechanics. We demonstrate that cell expansion is regulated by protein-mediated changes in cell wall extensibility driven by the circadian clock. By contrast, the biosynthesis of cellulose is controlled through intracellular trafficking of cellulose synthase enzyme complexes regulated exclusively by metabolic signaling related to the carbon status of the plant and independently of the circadian clock or light signaling.

Loop-mediated isothermal amplification is known for its high sensitivity, specificity and tolerance to inhibiting-substances. In this work, we developed a device for performing real-time colorimetric LAMP combining the accuracy of lab-based quantitative analysis with the simplicity of point-of-care testing. The device innovation lies on the use of a plastic tube anchored vertically on a hot surface while the side walls are exposed to a mini camera able to take snapshots of the colour change in real time during LAMP amplification. Competitive features are the rapid analysis (< 30 min), quantification over 9 log-units, crude sample-compatibility (saliva, tissue, swabs), low detection limit (< 5 copies/reaction), smartphone-operation, fast prototyping (3D-printing) and ability to select the dye of interest (Phenol red, HNB). The device's clinical utility is demonstrated in cancer mutations-analysis during the detection of 0.01% of BRAF-V600E-to-wild-type molecules from tissue samples and COVID-19 testing with 97% (Ct < 36.8) and 98% (Ct < 30) sensitivity when using extracted RNA and nasopharyngeal-swabs, respectively. The device high technology-readiness-level makes it a suitable platform for performing any colorimetric LAMP assay; moreover, its simple and inexpensive fabrication holds promise for fast deployment and application in global diagnostics.

A novel alternative to microcloning for the production of region specific chromosomal DNA is described. In this method, 'microamplification', single bands are dissected from polytene chromosomes and digested with Sau3A. Oligonucleotide adaptors are ligated to these fragments to provide convenient priming sites for polymerase chain reaction amplification. In this way, as much as 1 microgram of DNA can be amplified from a single band. Probes made from PCR amplified DNA from two such dissections have been used to probe cloned DNA form a 100 kb chromosome walk. Whereas conventional microcloning has generated cloned EcoRI fragments corresponding to 3-4 kb of the walk, the PCR probes cover greater than 90% of this chromosomal region. Thus microamplification is significantly more effective than microcloning in providing probes for establishing chromosomal walks.

Microbiome data predictive analysis within a machine learning (ML) workflow presents numerous domain-specific challenges involving preprocessing, feature selection, predictive modeling, performance estimation, model interpretation, and the extraction of biological information from the results. To assist decision-making, we offer a set of recommendations on algorithm selection, pipeline creation and evaluation, stemming from the COST Action ML4Microbiome. We compared the suggested approaches on a multi-cohort shotgun metagenomics dataset of colorectal cancer patients, focusing on their performance in disease diagnosis and biomarker discovery. It is demonstrated that the use of compositional transformations and filtering methods as part of data preprocessing does not always improve the predictive performance of a model. In contrast, the multivariate feature selection, such as the Statistically Equivalent Signatures algorithm, was effective in reducing the classification error. When validated on a separate test dataset, this algorithm in combination with random forest modeling, provided the most accurate performance estimates. Lastly, we showed how linear modeling by logistic regression coupled with visualization techniques such as Individual Conditional Expectation (ICE) plots can yield interpretable results and offer biological insights. These findings are significant for clinicians and non-experts alike in translational applications.

We propose, solve, and discuss a simple model for a metamaterial incorporating optical gain: A single bosonic resonance is coupled to a fermionic (inverted) two-level-system resonance via local-field interactions. For given steady-state inversion, this model can be solved analytically, revealing a rich variety of (Fano) absorption/gain lineshapes. We also give an analytic expression for the fixed inversion resulting from gain pinning under steady-state conditions. Furthermore, the dynamic response of the "lasing SPASER", i.e., its relaxation oscillations, can be obtained by simple numerical calculations within the same model. As a result, this toy model can be viewed as the near-field-optical counterpart of the usual LASER rate equations.

The plasmonic version of a 3D chiral meta‐atom which consists of a loop‐wire structure, namely the so‐called twisted omega particle, is experimentally realized. The structure is fabricated by direct laser writing and subsequent electroless silver plating, a novel technique capable of producing truly 3D photonic nanostructures. In this case, the metallic wire of finite length supports an electric dipole resonance, whereas the loop acts as a split‐ring resonator which exhibits a magnetic dipole resonance, leading to the separation of right‐handed circularly polarized light and the left‐handed one. The arising optical activity is discussed in terms of a single oscillator model system used classically to describe the generation of natural optical activity in chiral media, and it is shown that the twisted omega particle acts as its exact plasmonic analogue.

Journal Article Unified user interface design: designing universally accessible interactions Get access Anthony Savidis, Anthony Savidis aInstitute of Computer Science, Foundation for Research and Technology—Hellas, Science and Technology Park of Crete, Heraklion, Crete, GR-71110, Greece Search for other works by this author on: Oxford Academic Google Scholar Constantine Stephanidis Constantine Stephanidis ∗ aInstitute of Computer Science, Foundation for Research and Technology—Hellas, Science and Technology Park of Crete, Heraklion, Crete, GR-71110, GreecebDepartment of Computer Science, University of Crete, Greece ∗Corresponding author. Address: Institute of Computer Science, Foundation for Research and Technology—Hellas, Science and Technology Park of Crete, Heraklion, P.O. Box 1385, Crete GR-71110, Greece. Tel.: +30-2810-391741; fax: +30-2810-391740 Search for other works by this author on: Oxford Academic Google Scholar Interacting with Computers, Volume 16, Issue 2, April 2004, Pages 243–270, https://doi.org/10.1016/j.intcom.2003.12.003 Published: 01 April 2004 Article history Received: 07 January 2002 Revision received: 09 December 2002 Accepted: 14 December 2003 Published: 01 April 2004