Perfect Visibility Research Articles

Optical and Structural Developments in Air Traffic Control Tower Glazing

With about 4,500 medium and large airports around the world, Air Traffic Control Towers (ATCT) are essential elements of our transport infrastructure. Safely orchestrating air traffic requires a perfect visibility of aircraft in all weather and lighting conditions. Aviation being a conservative field, towers are built or renovated using decades-old technologies, with disappointing results. Design parameters can be grouped in five categories: structural, blemishes, insulation, photometric and optical. Transcending country borders and traditions, we will detail each of these groups and explain the newest technical solutions available. This paper can be used as a checklist or design guide if you need to conceive an ATCT or other structures, such as an indoor observation deck or high-end retail storefront, where vision is paramount. Special attention will be given to visual distortion in transmission, haze, anisotropy, double image, reflection management, electrochromic, and glass-to-glass connections.

Approaching Maximal Precision of Hong-Ou-Mandel Interferometry with Nonperfect Visibility.

In quantum mechanics, the precision achieved in parameter estimation using a quantum state as a probe is determined by the measurement strategy employed. The quantum limit of precision is bounded by a value set by the state and its dynamics. Theoretical results have revealed that in interference measurements with two possible outcomes, this limit can be reached under ideal conditions of perfect visibility and zero losses. However, in practice, these conditions cannot be achieved, so precision never reaches the quantum limit. But how do experimental setups approach precision limits under realistic circumstances? In this Letter, we provide a model for precision limits in two-photon Hong-Ou-Mandel interferometry using coincidence statistics for nonperfect visibility and temporally unresolved measurements. We show that the scaling of precision with visibility depends on the effective area in time-frequency phase space occupied by the state used as a probe, and we find that an optimal scaling exists. We demonstrate our results experimentally for different states in a setup where the visibility can be controlled and reaches up to 99.5%. In the optimal scenario, a ratio of 0.97 is observed between the experimental precision and the quantum limit, establishing a new benchmark in the field.

A Teutonic stronghold in the Carpathian Mountains

The HiLands Project (2018-2022) brought the opportunity to investigate several main communication corridors within the Curvature Carpathians. At the northern end of Rucăr-Bran Pass we had a great surprise, finding in the woods three strongholds, just one kilometre west of Bran Castle. Several trips on the mountain and two short digging sessions uncovered two hillforts made by the Teutonic Order, and a third one, shortly after they left. Hidden in dense forests, they have been deserted and forgotten, not being recorded in any historical accounts. The two western strongholds are enclosed by a common outer palisade, as they were built and used together. They are rather small, each with two rows of palisades, separated by a large ditch. The eastern one firstly served as a chalk quarry for the above-mentioned buildings, but two or three generations later was turned into a fortification. The northern long side is made up by a bare cliff, almost vertical, the southern side is closed by a large palisade, with no ditch (as it was not necessary due to the strong slopes). The downside of our research is the almost complete lack of artefacts from the 13th century, the proposed chronology being based exclusively on C14 AMS technology. Such a situation fuelled the question whether the western complex could be one of the five attested Teutonic fortresses. Its position is outstanding, offering perfect visibility up to the Bran Pass (10 km southward) or down to the Râşnov fortress (12 km northward).

Real‐Time Superresolution Interferometric Measurement Enabled by Structured Nonlinear Optics

AbstractOptical interferometers are pillars of modern precision metrology, but their resolution is limited by the wavelength of the light source, which cannot be infinitely reduced. Magically, this limitation can be circumvented by using an entangled multiphoton source because interference produced by an N‐photon amplitude features a reduced de Broglie wavelength . However, the extremely low efficiency in multiphoton state generation and coincidence counts actually negates the potential of using multiphoton states in practical measurements. Here, a novel interferometric technique based on structured nonlinear optics is demonstrated, i.e., parametric upconversion of a structured beam, capable of superresolution measurement in real time. The main principle relies in that the orbital angular momentum (OAM) state and associated intramodal phase within the structured beam are both continuously multiplied in cascading upconversion to mimic the superresolved phase evolution of a multiphoton amplitude. Owing to the use of bright sensing beams and OAM mode projection, up to a 12‐photon de Broglie wavelength with almost perfect visibility is observed in real time and, importantly, by using only a low‐cost detector. The results open the door to real‐time superresolution interferometric metrology and provide a promising way toward multiphoton superiority in practical applications.

Perceptual Displays Today & Tomorrow – Evangelism, Productization, and Evaluation

Evolution of displays in various industries such as consumer electronics, aerospace, automotive, gaming and digital signage has been a key factor to engage and satisfy consumers. In this talk, I focus on Automotive market as one of the fastest growing display markets, but most discussed matters are applicable to other display verticals. Perceptual and Immersive display user experience are attracting more manufacturers these days to build products matching the end user’s expectation and needs while interacting with displays such as: perfect visibility in all conditions, personalization, less eye fatigue, seamless interaction - in one word “mimic real world” experience. Hardware and software advancements are critical but not enough to fulfil today’s knowledgeable consumer demands. The User Experience has become one of the highest priorities leading companies to develop dedicated user experience or UX teams to study the need of the end user. Multi-disciplinary teams of experts are built to tackle the UX optimization challenge._x005F_x000D_ _x005F_x000D_ In this talk I will share our experience evangelizing the benefits of Perceptual displays, challenges of such evangelism, productization of it and most importantly measuring the performance of perceptual displays in a comparable way to traditional displays.

Blockchain-Enabled Deep-Tier Supply Chain Finance

Problem definition: For many supply chains, deep-tier suppliers, due to their small size and lack of access to capital, are most vulnerable to disruptions. We study the use of advance payment (AP) as a financing instrument in a multitier supply chain to mitigate the supply disruption risk in a traditional system (with limited visibility) and a blockchain-enabled system (with perfect visibility). The main goal of this paper is to shed light on how blockchain adoption impacts agents’ operational and financial decisions as well as profit levels in a multitier supply chain. Academic/practical relevance: Traditionally, because of the limited visibility in the deep tiers, powerful downstream manufacturers’ financing schemes offered to their immediate upstream suppliers are not effective in instilling capital into the deep tiers. Advancements in blockchain technology improve the supply chain visibility and enable the manufacturer to better devise deep-tier financing to improve supply chain resilience. Methodology: We develop a three-tier supply chain model and take a game-theoretic approach to compare how blockchain-enabled deep-tier financing schemes affect a financially constrained supply chain’s optimal risk-mitigation and financial strategies. Results: We find that although improved visibility via blockchain adoption can help the manufacturer make informed supply chain financing decisions, whether it can benefit all supply chain members depends on the financing schemes in use. Blockchain-enabled delegate financing increases risk-mitigation investments and benefits all three tiers of the supply chain only when the tier 2 supplier is severely capital-constrained with the working capital below a threshold. Because delegate financing endows the intermediary tier 1 supplier with leverage over the manufacturer, the inefficiency inhibits an all-win outcome when the tier 2 supplier is not severely capital-constrained. Blockchain-enabled cross-tier direct financing exhibits a compelling performance as it always leads to win-win-win outcomes (and is thus ubiquitously implementable) regardless of the suppliers’ working capital profile. Managerial implications: Our insights help firms assess opportunities and challenges associated with enhancing supply chain visibility via blockchain adoption.

Device-independent quantum key distribution based on Bell inequalities with more than two inputs and two outputs

Device-independent quantum key distribution (DI-QKD) offers the strongest form of security against eavesdroppers bounded by the laws of quantum mechanics. However, a practical implementation is still pending due to the requirement of combinations of visibility and detection efficiency that are beyond those possible with current technology. This mismatch motivates the search for DI-QKD protocols that can close the gap between theoretical and practical security. In this work, we present two DI-QKD protocols whose security relies on Bell inequalities with more than two inputs and two outputs. We show that, for maximally entangled states and perfect visibility, a protocol based on a Bell inequality with three inputs and four outputs requires a slightly lower detection efficiency than the protocols based on Bell inequalities with two inputs and two outputs.

Blockchain-Enabled Deep-Tier Supply Chain Finance

Problem Definition: For many supply chains, deep-tier suppliers, due to their small sizes and lack of access to capital, are most vulnerable to disruptions. In this paper, we study the use of advance payment (AP) as a financing instrument in a multitier supply chain to mitigate the supply disruption risk and compare the traditional system (deep-tier financing with limited visibility) with the blockchain-enabled system (financing with perfect visibility). The main goal of this paper is to shed light on how blockchain adoption impacts agents' operational and financial decisions as well profit levels in a multitier supply chain. Academic/Practical Relevance: Traditionally, because of the limited visibility in the deep-tiers, powerful downstream manufacturers' financing schemes offered to their immediate upstream suppliers are not effective in instilling capital into the deep-tiers. Advancements in blockchain technology improve the supply chain visibility and enable the manufacturer to better devise deep-tier financing to improve supply chain resilience. Methodology: We develop a three-tier supply chain model and take a game-theoretic approach to understand a financially constrained supply chain's optimal operational and financial strategies. Results: We find that the improved supply chain visibility (by blockchain adoption) always benefits the manufacturer by enabling her to induce the desired operational risk-mitigation investment from the tier-1 and tier-2 suppliers. However, depending on the directional change in the operational risk-mitigation investment, which depends on the suppliers' initial wealth levels, the tier-1 and tier-2 suppliers can be worse-off. The win-win-win outcome takes place only when all operational risk-mitigation measures increase, that is, when the tier-1 supplier is severely capital constrained but the tier-2 supplier is moderately capital constrained. Comparing the two types of blockchain-enabled deep-tier financing schemes, adjacent-tier delegated financing versus cross-tier direct financing, the manufacturer strictly prefers the latter. In contrast, the tier-1 supplier strictly prefers the former because the former endows the tier-1 with financial leverage over the manufacturer. The tier-2 supplier prefers the latter only when the emergency source is expensive. Managerial Implications: Our insights help firms assess opportunities and challenges associated with enhancing supply chain visibility via blockchain adoption.

The photon: the role of its mode function in analyzing complementarity

We investigate the role of the spatial mode function in a single-photon experiment designed to demonstrate the principle of complementarity. Our approach employs entangled photons created by spontaneous parametric downconversion from a pump mode in a TEM01 mode together with a double slit. Measuring the interference of the signal photons behind the double slit in coincidence with the entangled idler photons at different positions, we select signal photons of different mode functions. When the signal photons belong to the TEM01-like double-hump mode, we obtain almost perfect visibility of the interference fringes, and no “which slit” information is available in the idler photon detected before the slits. This result is remarkable because the entangled signal and idler photon pairs are created each time in only one of the two intensity humps. However, when we break the symmetry between the two maxima of the signal photon mode structure, the paths through the slits for these additional photons become distinguishable and the visibility vanishes. It is the mode function of the photons selected by the detection system that decides if interference or “which slit” information is accessible in the experiment.

Hybrid Experimental Rocket Stuttgart: A Low-Cost Technology Demonstrator

On 8 November 2016 at 1030 hrs, the Hybrid Experimental Rocket Stuttgart (HEROS) 3 was launched from the European Space and Sounding Rocket Range (ESRANGE) Space Center to an apogee altitude of 32,300 m (106,000 ft). This set a new altitude record for European student and amateur rocketry and a world altitude record for hybrid rockets built by students. The 7.5-m-long rocket was using nitrous oxide () and a paraffin-based fuel to produce 10,000 N of thrust. The dry mass of the rocket was only 75 kg thanks to a carbon fiber structure for the most part. The rocket performed the record-breaking flight at perfect weather and visibility conditions, reaching a maximum airspeed of and Mach 2.3. The rocket performed a soft landing with two parachutes and can be reused. Flight data and engine performance data are published and analyzed. The flight data show excellent stability of the rocket. Engine performance data prove very high efficiency and stable combustion. The subsystem design and verification before the launch is reported. Engine and flight trajectory simulations show very good agreement with the flight data. Furthermore, the overall project, rocket design, and subsystems, as well as the launch campaign, are presented here in detail.

Novel needle guide reduces time to perform ultrasound-guided femoral nerve catheter placement: A randomised controlled trial.

Ultrasound-guided nerve blocks have become the standard when performing regional nerve blocks in anaesthesia. Infiniti Plus (CIVCO Medical Solutions, Kalona, Iowa, USA) is a needle guide that has been recently developed to help clinicians in performing ultrasound-guided nerve blocks. We tested the hypothesis that femoral nerve catheter placement carried out with the Infiniti Plus needle guide will be quicker to perform than without the Infiniti Plus. Secondary aims were to assess whether the Infiniti Plus needle guide decreased the number of block attempts and also whether it improved needle visibility. A randomised, controlled trial. Cleveland Clinic, Cleveland, Ohio, USA. We enrolled adult patients having elective total knee arthroplasty with a femoral nerve block and femoral nerve catheter. Patients, who were pregnant or those who had preexisting neuropathy involving the surgical limb, coagulopathy, infection at the block site or allergy to local anaesthetics were excluded. Patients were randomised into two groups to receive the ultrasound-guided femoral nerve catheter placement with or without the Infiniti Plus needle guide. The time taken to place the femoral nerve catheter, the number of attempts, the success rate and needle visibility were recorded. We used an overall α of 0.05 for both the primary and secondary analyses; the secondary analyses were Bonferroni corrected to control for multiple comparisons. The median (interquartile range Q1 to Q3) time to perform the femoral nerve catheter placement was 118 (100 to 150) s with Infiniti Plus and 177 (130 to 236) s without Infiniti Plus. Infiniti Plus significantly reduced the time spent performing femoral nerve catheterisation, with estimated ratio of means [(95% confidence interval), P value] of 0.67 [(0.60 to 0.75), P < 0.001] with Infiniti Plus compared with no Infiniti Plus. However, Infiniti Plus had no effect on the odds of a successful femoral nerve catheter placement, number of attempts or percentage of perfect needle visibility. We found that the use of Infiniti Plus decreased the median time to successfully place a femoral nerve catheter by 33% compared with not using Infiniti Plus. This difference may be more apparent to clinicians undertaking this procedure less often or by those in training as our team was very experienced, had been trained in the technique and was working in a hospital with a large caseload. Clinicaltrials.gov identifier: NCT02080481.

High Visibility Time-Energy Entangled Photons from a Silicon Nanophotonic Chip

Advances in quantum photonics have shown that chip-scale quantum devices are translating from the realm of basic research to applied technologies. Recent developments in integrated photonic circuits and single photon detectors indicate that the bottleneck for fidelity in quantum photonic processes will ultimately lie with the photon sources. We present and demonstrate a silicon nanophotonic chip capable of emitting telecommunication band photon pairs that exhibit the highest raw degree of time-energy entanglement from a micro/nanoscale source, to date. Biphotons are generated through cavity-enhanced spontaneous four-wave mixing (SFWM) in a high-Q silicon microdisk resonator, wherein the nature of the triply-resonant generation process leads to a dramatic Purcell enhancement, resulting in highly efficient pair creation rates as well as extreme suppression of the photon noise background. The combination of the excellent photon source and a new phase locking technique, allow for the observation of a nearly perfect coincidence visibility of (96.6 $\pm$ 1.1)$\%$, without any background subtraction, at a large pair generation rate of (4.40 $\pm$ 0.07) $\times$ 10$^5$ pairs/s.

Spin-Based Mach-Zehnder Interferometry in Topological Insulator p-n Junctions.

Transport in three-dimensional topological insulators relies on the existence of a spin-momentum locked surface state that encloses the insulating bulk. In this work we show how, in a topological insulator p-n junction, a magnetic field turns this surface state into an electronic Mach-Zehnder interferometer. Transmission of the junction can be tuned from zero to unity, resulting in virtually perfect visibility of the interference pattern, and the reflected and transmitted currents carry opposite spin polarization so that the junction also acts as a spin filter. Our setup therefore realizes a novel and highly tunable spintronic device where the effects of spin-momentum locking in topological insulator surface states can be probed directly in a transport experiment.

Foucault, pastoral power, and optics

The article shows that in Foucault’s late 1970s and early 1980s analyses of pastoral, conductive power—most essentially in early and medieval Christianity—the issue of sight and visual perception recurs and occupies a crucial status. In Foucault’s discussion, these Christian relations of power, knowledge, and truth are attached with a surveying gaze that is both totalizing as well as individualizing, one that is mobilized by the thrust towards perfect visibility, transparency, and illumination of the subject turned into an object. The intention is also to develop Foucault’s analysis further, by demonstrating how Christian, providential government can be and actually has been detached from the totalizing modality of optics, and instead become articulated with a very different sort of sight and seeing, one that is non-totalizing and affirms its own limits. The article maintains that from this angle, Foucault’s conception of modern, economic-liberal governmentality has essential convergences with the Christian form of providential government, even though Foucault himself leaves these convergences partly inarticulate.

Induced coherence, vacuum fields, and complementarity in biphoton generation.

It is well established that spontaneous parametric down-conversion with induced coherence across two coupled interferometers results in high-visibility single-photon interference. We describe experiments in which additional photon channels are introduced such that "which-path" information is made possible and the fringe visibility in single-photon interference is reduced in accordance with basic notions of complementarity. However, these additional pathways result in nearly perfect visibility when photons are counted in coincidence. A simplified theoretical model accounts for these observations and attributes them directly to the vacuum fields at the different crystals.

Evacuation under limited visibility

A multiplicity of situations can trigger off an evacuation of a room under panic conditions. For "normal" (with "normal" meaning absence of obstacles, perfect visibility, etc.) environmental conditions, the "faster is slower" effect dominates the dynamics of this process. It states that as the pedestrians desire to reach the exit increases, the clogging phenomena delays the time to get out of the room. But, environmental conditions are usually far from "normal." In this work, we consider that pedestrians have to find their way out under low visibility conditions. Some of them might switch to a herding-like behavior if they do not remember where the exit was. Others will just trust on their memory. Our investigation handles the herding and memory effects on the evacuation of a single exit room with no obstacles. We also include a section on how signaling devices affect the evacuation process. Unexpectedly, some low visibility situations may enhance the evacuation performance. This can be resumed as a second paradoxical result, since we demonstrated in an earlier investigation that "clever is not always better" G. A. Frank and C. O. Dorso, Physica A 390, 2135 (2011).

Two-photon interference between disparate sources for quantum networking

Quantum networks involve entanglement sharing between multiple users. Ideally, any two users would be able to connect regardless of the type of photon source they employ, provided they fulfill the requirements for two-photon interference. From a theoretical perspective, photons coming from different origins can interfere with a perfect visibility, provided they are made indistinguishable in all degrees of freedom. Previous experimental demonstrations of such a scenario have been limited to photon wavelengths below 900 nm, unsuitable for long distance communication, and suffered from low interference visibility. We report two-photon interference using two disparate heralded single photon sources, which involve different nonlinear effects, operating in the telecom wavelength range. The measured visibility of the two-photon interference is 80 ± 4%, which paves the way to hybrid universal quantum networks.

The effects of spatial and temporal cueing on metacontrast masking

We studied the effects of selective attention on metacontrast masking with 3 different cueing experiments. Experiments 1 and 2 compared central symbolic and peripheral spatial cues. For symbolic cues, we observed small attentional costs, that is, reduced visibility when the target appeared at an unexpected location, and attentional costs as well as benefits for peripheral cues. All these effects occurred exclusively at the late, ascending branch of the U-shaped metacontrast masking function, although the possibility exists that cueing effects at the early branch were obscured by a ceiling effect due to almost perfect visibility at short stimulus onset asynchronies (SOAs). In Experiment 3, we presented temporal cues that indicated when the target was likely to appear, not where. Here, we also observed cueing effects in the form of higher visibility when the target appeared at the expected point in time compared to when it appeared too early. However, these effects were not restricted to the late branch of the masking function, but enhanced visibility over the complete range of the masking function. Given these results we discuss a common effect for different types of spatial selective attention on metacontrast masking involving neural subsystems that are different from those involved in temporal attention.

Mandibular nerve block can improve intraoperative inferior alveolar nerve visualization during sagittal split mandibular osteotomy

Introduction The main procedure specific complication of sagittal split osteotomy of the mandibular ramus (SSOMR) is inferior alveolar nerve (IAN) injury. This can be produced by poor intraoperative visibility of the IAN due to bone bleeding. In our centre, mandibular nerve blocks (MNBs) are usually performed for intra- and post-operative analgesia. We observed that MNB seems to decrease intraoperative bleeding and thus to improve IAN visibility. Our study was performed to evaluate the effect of MNB on intraoperative bleeding during SSOMR and, secondarily, on the duration of this procedure. Material and methods Patients scheduled for bilateral SSOMR under general anaesthesia were prospectively randomized into two groups. The Block group received bilateral MNB (5 mL ropivacaine 0.5% for each block) and the Control group sham MNBs (bilateral cutaneous puncture, without block). The operations were carried out under a standardised general anaesthetic. Post-operatively, the surgeon, blinded to group allocation, assessed intraoperative bone bleeding using a Numerical Rating Scale (NRS) (0: no bleeding, perfect visibility to 100: major bleeding, no visibility). Osteotomy duration, intraoperative anaesthetic requirements, and pain score in the recovery room were also recorded. Results are expressed as median [25–75th percentiles]. Results Nineteen patients were included in each group. Osteotomy under MNB had a decreased intraoperative bone bleeding score compared with controls (20 [0–40] versus 55 [20–80], p = 0.0002). They had a dry surgical field more frequently (29% versus 5%, p = 0.01), and a shorter mean time for the osteotomy (15 [12.25–17.75] versus 17.5 [15–21] min, p = 0.009). Block patients had reduced intraoperative opioid consumption (770 [678–1430] versus 2310 [1908–3058] mcg of remifentanil, p = 0.0001), and lower pain scores in the recovery room (0 [0–2] versus 3 [1–5], p = 0.12). Conclusion MNB decreases intraoperative bone bleeding during SSOMR under general anaesthesia. Three hypotheses to explain this result are discussed.

An analysis of imperfect RFID visibility in a multi-echelon supply chain

This study investigates how imperfect inventory information provided by Radio Frequency Identification (RFID) technology can be used in inventory management. A simulation-based approach is utilised to understand the potential uses and impacts of imperfect RFID data in multi-echelon retail supply chains. The results reveal that when used as the primary decision-making tool, RFID could be a valuable technology even without perfect visibility. However, unforeseen trends and system behaviours are observed on the level of inventory record inaccuracy. When RFID is used to monitor the inventory as a supporting technology, the information provided can be used to trigger inventory correction activities.