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In this paper, we study both theoretically and experimentally the sensitivity of bimodal interferometric sensors where interference occurs between two plasmonic modes with different properties propagating in the same physical waveguide. In contrast to the well-known Mach–Zehnder interferometric (MZI) sensor, we show for the first time that the sensitivity of the bimodal sensor is independent of the sensing area length. This is validated by applying the theory to an integrated plasmo-photonic bimodal sensor that comprises an aluminum (Al) plasmonic stripe waveguide co-integrated between two accessible SU-8 photonic waveguides. A series of such bimodal sensors utilizing plasmonic stripes of different lengths were numerically simulated, demonstrating bulk refractive index (RI) sensitivities around 5700 nm/RIU for all sensor variants, confirming the theoretical results. The theoretical and numerical results were also validated experimentally through chip-level RI sensing experiments on three fabricated SU-8/Al bimodal sensors with plasmonic sensing lengths of 50, 75, and 100 μm. The obtained experimental RI sensitivities were found to be very close and equal to 4464, 4386, and 4362 nm/RIU, respectively, confirming that the sensing length has no effect on the bimodal sensor sensitivity. The above outcome alleviates the design and optical loss constraints, paving the way for more compact and powerful sensors that can achieve high sensitivity values at ultra-short sensing lengths. [ABSTRACT FROM AUTHOR]

Objective: Rare disease Background: Non-calculus foreign bodies in the bladder are rare and are usually introduced via the urethra. Reports of the migration of metallic foreign bodies from previous surgery are uncommon and mainly associated with surgical screws used for the internal fixation of pubic bone fracture and total hip replacement. This report is of a 56-year-old woman presenting with a surgical screw foreign body in the bladder 19 years after open surgical reduction and internal plate and screw fixation of traumatic fracture of the pubic bone. Case Report: A 56-year-old woman visited a urologist because of gross hematuria. She mentioned a mild pelvic pain and multiple lower urinary tract infections over the past 2 years, with no other symptoms. From the previous history, she had undergone an open reduction and internal fixation of the pelvic ring, with surgical plates and screws following pubic bone's fracture, due to an accident 19 years earlier. Cystoscopy identified the presence of a screw head protruding into the bladder wall. The screw was extracted via open surgery, and the patient was discharged 2 days later. Conclusions: While intravesical foreign bodies are rarely seen in Emergency Departments, clinicians should maintain a level of suspicion in certain cases. The purpose of this case report is to present the unlikely and delayed complication of internal pubic bone fixation resulting in the migration of a fixation screw to the bladder. It also highlights the importance of imaging in diagnosis and localization of the foreign body in the bladder. [ABSTRACT FROM AUTHOR]

Background: Τhe study aims to identify factors associated with COVID-19 vaccine acceptance and to investigate knowledge and perceptions of Primary Health Care Centers (PHCC) personnel, who acted as pioneers in the national COVID-19 vaccination strategy. Methods and Materials: A nationwide cross-sectional survey was conducted by distributing an online anonymous questionnaire comprising 25 questions during the first semester of 2021. Results: Approximately 85.3% of the 1136 respondents (response rate 28.4%) were vaccinated or intended to be. The acceptance of seasonal flu vaccine (aOR: 3.29, 95%CI: 2.08–5.20), correct COVID-19 vaccine knowledge (aOR: 8.37, 95%CI: 4.81–14.59) and lack of concern regarding vaccine novelty (aOR: 6.18, 95%CI: 3.91–9.77) were positively correlated with vaccine acceptance. Vaccinated respondents were more likely to be physicians (aOR: 2.29, 95%CI: 1.03–5.09) or administrative staff (aOR: 2.65, 95%CI: 1.18–5.97) compared to nursing stuff. Reasons for vaccine hesitancy included inadequate information (37.8%) and vaccine safety (31.9%). Vaccine acceptance was strongly correlated (Spearman's correlation coefficient r = 0.991, p < 0.001) between PHCC personnel and the general population of each health district. Conclusions: COVID-19 vaccine acceptance among PHCC personnel in Greece was comparably high, but specific groups (nurses) were hesitant. As the survey's target population could serve as a role model for the community, efforts should be made to improve COVID-19 vaccine acceptance. [ABSTRACT FROM AUTHOR]

Duringthe past years, incorporating Οptical Circuit Switches (OCS) in high-bandwidth optical interconnects has outlined the critical challenges of achieving ultra-low fiber-to-fiber losses (FtF) and constantly decreasing costs for Photonic Integrated Circuits (PICs). This work aims to simultaneously satisfy both the low-loss and low-cost requirements by bringing two of the most successful example-technologies in the history of optics, i.e., EDFAs and ROADMs to a common Si3N4 platform. In particular, the proof-of-concept operation of a lossless four-port Silicon Photonic (SiPho) ROADM is experimentally presented for the first time based on two PIC prototypes on a Si3N4 platform, including a monolithic-integrated 5.9 cm-long spiral Al2O3:Er3+ Erbium Doped Waveguide Amplifier (EDWA) with 15 dB signal enhancement capabilities and a lattice MZI-interleaver ROAM layout with 100 GHz channel spacing. Considering an ultra-low 2.55 dB FtF loss of the ROADM along with 0.5 dB loss for each of the two coupling-interfaces between the Si3N4 and Al2O3:Er3+ waveguide layers, a cumulative loss of 3.55 dB is obtained, which can be compensated by the 3.6 dB net gain provided by the EDWA to four incoming WDM signals of −1.7 dBm/channel. Lossless wavelength-routing operation is validated at up to 240 Gb/s WDM (4λ × 60 Gb/s) data traffic, while the cascadability of the proposed device is benchmarked in a realistic two-stage optical bus topology with 10 km single mode fiber that selectively routes 4λ × 25 Gb/s WDM data channels to any of its eight Drop output ports. This work forms the first demonstration of lossless ROADM operation exclusively on SiPho technology, highlighting a promising roadmap for large scale SiPho switching matrices and more complex PICs co-integrated with EDWAs. [ABSTRACT FROM AUTHOR]

The increasing need for more efficient communication networks has been the main driving force for the development of complex photonic integration circuits combining active and passive building blocks towards advanced functionality. However, this perpetual effort comes with the cost of additive power losses and the research community has resorted to the investigation of different materials to establish efficient on-chip amplification. Among the different proposals, erbium-doped waveguide amplifiers appear to be a promising solution for high performance transmission in the C-band band with low fabrication cost, due to their CMOS compatibility and integration potential with the silicon\silicon nitride photonic platforms. In this paper we provide a holistic study for high-speed WDM transmission capabilities of a monolithically integrated Al2O3:Er3+ spiral waveguide amplifier co-integrated with Si3N4 components, providing a static characterization and a dynamic evaluation for (a) 4 × 40 Gbps, (b) 8 × 40 Gbps and (c) 8×60 Gbps WDM transmissions achieving clearly open eye diagram in all cases. The active region of the erbium doped waveguide amplifier consists of a 5.9 cm Al2O3:Er3+ spiral adiabatically coupled to passive Si3N4 waveguides combined with on chip 980 nm/1550 nm WDM Multiplexers/Demultiplexers. Experimental results reveal bit-error rate values below the KR4-FEC limit of 2×10-5 for all channels, without any DSP applied on the transmitter or receiver side for a 4×40 Gbps and 8×40 Gbps data stream transmission. [ABSTRACT FROM AUTHOR]

A plethora of evidence can be found in the literature supporting the view that citizens' trust in the state plays a decisive role in their overall tax compliance. Nevertheless, in Greece, where the consequences of a ten years long economic crisis still exist, the phenomenon of tax evasion is still dealt with traditional enforcement methods like penalties, regular audits, and tax policy. A new conceptual model is proposed and empirically tested using data from 1,014 Greek citizens from fifty areas of Greece. It attempts to examine the combined effect of ten trust-related factors, which are grouped into four dimensions on tax morale (trust in governance quality, trust in principles and institutions, trust in fellow citizens and trust in personal perceptions). The results show that Greek citizens' trust in tax reciprocity is the factor that mainly affects tax morale, with citizens' trust in tax authorities and in the institution of democracy closely following. [ABSTRACT FROM AUTHOR]

During the past years, optical memories have emerged as the main way to enable fast access times and increased memory bandwidth in synergy with optical interconnections. The migration, however, to fully functional and practical optical RAMs and cache memories will require an additional yet essential step: Optical memories have to get organized into an optical memory subsystem for delivering seamless cooperation between storage and peripheral decoding units, exploiting also the wavelength dimension for efficient RAM architectural layouts. In this paper we demonstrate the first experimentally verified Wavelength Division Multiplexing (WDM) -enabled optical RAM Row subsystem comprising both the peripheral decoding circuitry and a 4-bit optical RAM Row for storing 20Gb/s 4-bit WDM-formatted optical data words. The proposed scheme comprises a single shared multi-λ Semiconductor Optical Amplifier Mach-Zehnder Interferometer (SOA-MZI) Access Gate (AG) for granting access-control to the complete RAM Row, a passive Column Decoder (CD) that directs the incoming WDM-formatted data words to the respective RAM cells that are in turn based on four broadband Indium Phosphide (InP) photonic integrated Flip-Flops (FFs). Our experimental verification firstly investigates the broadband capability of the elementary InP monolithic RAM cell at 5 Gb/s, revealing error-free Write functionality with <4.5 dB power penalty across the whole C-band confirming in this way the potential of efficient scaling to multi-cell WDM-enabled RAMs. Then, experimental validation of the complete 4-bit WDM-enabled optical RAM Row with 20 Gb/s WDM-formatted data words is performed, featuring simultaneous Access gating, decoding and storage operation for all four RAM cells, having a peak power penalty within the range of [4.6-5.6] dB for Write and [2.2-2.9] dB for Read functionalities, respectively, at a Bit Error Rate of 10−9. [ABSTRACT FROM AUTHOR]

Multi‐socket server boards (MSBs) exploit the interconnection of multiple processor chips towards forming powerful cache coherent systems, with the interconnect technology comprising a key element in boosting processing performance. Here, we present an overview of the current electrical interconnects for MSBs, outlining the main challenges currently faced. We propose the use of silicon photonics (SiPho) towards advancing interconnect throughput, socket connectivity and energy efficiency in MSB layouts, enabling a flat‐topology wavelength division multiplexing (WDM)‐based point‐to‐point (p2p) optical MSB interconnect scheme. We demonstrate WDM SiPho transceivers (TxRxs) co‐assembled with their electronic circuits for up to 50 Gb/s line rate and 400 Gb/s aggregate data transmission and SiPho arrayed waveguide grating routers that can offer collision‐less time of flight connectivity for up to 16 nodes. The capacity can scale to 2.8 Gb/s for an eight‐socket MSB, when line rate scales to 50 Gb/s, yielding up to 69% energy reduction compared with the QuickPath Interconnect and highlighting the feasibility of single‐hop p2p interconnects in MSB systems with >4 sockets. [ABSTRACT FROM AUTHOR]

A silicon photonic circuit comprising all the building blocks necessary to demonstrate optical communication between two sockets interconnected through an Arrayed Waveguide Grating Router (AWGR) is reported. The article focuses on the robustness of the interconnection scheme to the unavoidable wavelength and thermal fluctuations observed in real datacenter environments. To improve the reliability of the system, a feedback control mechanism, based on contactless integrated photonic probes (CLIPP) and heater actuators, is added to the interconnection to monitor in parallel the working point of each sensitive device and keep it locked in real-time. Experimental results demonstrate successful operations in a 30 Gbit/s data routing scenario at 5 ⋅ 10−11 bit error rate, irrespective of sudden wavelength shifts of up to 200 pm or of iterated thermal variations in a 10° C temperature range, with a recovery time of around 30 ms. These results prove that AWGR-based interconnections equipped with real-time drift compensation systems can be a viable option in multi-socket layouts even in highly demanding environments. [ABSTRACT FROM AUTHOR]

Arrayed Waveguide Grating Router (AWGR)-based interconnections for Multi-Socket Server Boards (MSBs) have been identified as a promising solution to replace the electrical interconnects in glueless MSBs towards boosting processing performance. In this article, we present an 8-socket glueless optical flat-topology Wavelength Division Multiplexing (WDM)-based point-to-point (P2P) interconnect pursued within the H2020 ICT project ICT-STREAMS and we report on our latest achievements in the deployment of the constituent silicon (Si)-photonic transmitter and routing building blocks, exploiting experimentally obtained performance metrics for analyzing the 8-socket chip-to-chip (C2C) connectivity in terms of throughput and energy efficiency. We demonstrate an 8-channel WDM Si-photonic microring-based transmitter (Tx) capable of providing 400 (8 × 50) Gb/s non-return-to-zero (NRZ) Tx capacity and an 8 × 8 Coarse-WDM (CWDM) Si-AWGR with verified cyclic data routing capability in O-band. Following an overview of our recently demonstrated crosstalk (XT)-aware wavelength allocation scheme, that enables fully-loaded AWGR-based interconnects even for typical sub-optimal XT values of silicon integrated CWDM AWGRs, we validate the performance of a full-scale 8-socket interconnect architecture through physical layer simulations exploiting experimentally-verified simulation models for the underlying Si-photonic Tx and routing circuits. This analysis reveals a total aggregate capacity of 1.4 Tb/s for an 8-socket interconnect when operating with 25 Gb/s line-rates, which can scale to 2.8 Tb/s at an energy efficiency of just 5.02 pJ/bit by exploiting the experimentally verified building block performance at 50 Gb/s line. This highlights the perspectives for up to 69% energy savings compared to the standard QuickPath Interconnect (QPI) typically employed in electronic glueless MSB interconnects, while scaling the single-hop flat connectivity from 4- to 8-socket interconnection systems. [ABSTRACT FROM AUTHOR]

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