| 1. |
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| 2. |
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| 3. |
- Lin, Yan-Shih, et al.
(författare)
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Optimal stomatal behaviour around the world
- 2015
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Ingår i: Nature Climate Change. - : Springer Science and Business Media LLC. - 1758-678X .- 1758-6798. ; 5, s. 459-464
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Tidskriftsartikel (refereegranskat)abstract
- Stomatal conductance (gs) is a key land-surface attribute as it links transpiration, the dominant component of global land evapotranspiration, and photosynthesis, the driving force of the global carbon cycle. Despite the pivotal role of gs in predictions of global water and carbon cycle changes, a globalscale database and an associated globally applicable model of gs that allow predictions of stomatal behaviour are lacking. Here,we present a database of globally distributed gs obtained in the field for a wide range of plant functional types (PFTs) and biomes. We find that stomatal behaviour differs among PFTs according to their marginal carbon cost of water use, as predicted by the theory underpinning the optimal stomatal model1 and the leaf and wood economics spectrum2,3.We also demonstrate a global relationship with climate. These findings provide a robust theoretical framework for understanding and predicting the behaviour of gs across biomes and across PFTs that can be applied to regional, continental and global-scale modelling of ecosystem productivity, energy balance and ecohydrological processes in a future changing climate.
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| 4. |
- Lin, Yan-Shih, et al.
(författare)
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Optimal stomatal behaviour around the world
- 2015
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Ingår i: Nature Climate Change. - 1758-6798 .- 1758-678X. ; 5:5, s. 459-464
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Tidskriftsartikel (refereegranskat)abstract
- Stomatal conductance (g(s)) is a key land-surface attribute as it links transpiration, the dominant component of global land evapotranspiration, and photosynthesis, the driving force of the global carbon cycle. Despite the pivotal role of g(s) in predictions of global water and carbon cycle changes, a global-scale database and an associated globally applicable model of g(s) that allow predictions of stomatal behaviour are lacking. Here, we present a database of globally distributed g(s) obtained in the field for a wide range of plant functional types (PFTs) and biomes. We find that stomatal behaviour differs among PFTs according to their marginal carbon cost of water use, as predicted by the theory underpinning the optimal stomatal model(1) and the leaf and wood economics spectrum(2,3). We also demonstrate a global relationship with climate. These findin g(s) provide a robust theoretical framework for understanding and predicting the behaviour of g(s) across biomes and across PFTs that can be applied to regional, continental and global-scale modelling of ecosystem productivity, energy balance and ecohydrological processes in a future changing climate.
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| 5. |
- Reyer, Christopher P. O., et al.
(författare)
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A plant's perspective of extremes : terrestrial plant responses to changing climatic variability
- 2013
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Ingår i: Global Change Biology. - HOBOKEN 07030-5774, NJ USA : John Wiley & Sons. - 1354-1013 .- 1365-2486. ; 19:1, s. 75-89
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Forskningsöversikt (refereegranskat)abstract
- We review observational, experimental, and model results on how plants respond to extreme climatic conditions induced by changing climatic variability. Distinguishing between impacts of changing mean climatic conditions and changing climatic variability on terrestrial ecosystems is generally underrated in current studies. The goals of our review are thus (1) to identify plant processes that are vulnerable to changes in the variability of climatic variables rather than to changes in their mean, and (2) to depict/evaluate available study designs to quantify responses of plants to changing climatic variability. We find that phenology is largely affected by changing mean climate but also that impacts of climatic variability are much less studied, although potentially damaging. We note that plant water relations seem to be very vulnerable to extremes driven by changes in temperature and precipitation and that heatwaves and flooding have stronger impacts on physiological processes than changing mean climate. Moreover, interacting phenological and physiological processes are likely to further complicate plant responses to changing climatic variability. Phenological and physiological processes and their interactions culminate in even more sophisticated responses to changing mean climate and climatic variability at the species and community level. Generally, observational studies are well suited to study plant responses to changing mean climate, but less suitable to gain a mechanistic understanding of plant responses to climatic variability. Experiments seem best suited to simulate extreme events. In models, temporal resolution and model structure are crucial to capture plant responses to changing climatic variability. We highlight that a combination of experimental, observational, and/or modeling studies have the potential to overcome important caveats of the respective individual approaches.
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| 6. |
- Mosconi, Dario, et al.
(författare)
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Site-Selective Integration of MoS2 Flakes on Nanopores by Means of Electrophoretic Deposition
- 2019
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Ingår i: ACS Omega. - : American Chemical Society (ACS). - 2470-1343. ; 4:5, s. 9294-9300
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Tidskriftsartikel (refereegranskat)abstract
- Here, we propose an easy method for site-selective deposition of two-dimensional (2D) material flakes onto nanoholes by means of electrophoretic deposition. This method can be applied to both simple flat nanostructures and complex three-dimensional structures incorporating nanoholes. The deposition method is here used for the decoration of large ordered arrays of plasmonic structures with either a single or few layers of MoS2. In principle, the plasmonic field generated by the nanohole can significantly interact with the 2D layer leading to enhanced light–material interaction. This makes our platform an ideal system for hybrid 2D material/plasmonic investigations. The engineered deposition of 2D materials on plasmonic nanostructures is useful for several important applications such as enhanced light emission, strong coupling, hot-electron generation, and 2D material sensors.
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| 7. |
- Pancaldi, Matteo, et al.
(författare)
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High-resolution ptychographic imaging at a seeded free-electron laser source using OAM beams
- 2024
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Ingår i: Optica. - 2334-2536. ; 11:3, s. 403-411
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Tidskriftsartikel (refereegranskat)abstract
- Electromagnetic waves possessing orbital angular momentum (OAM) are powerful tools for applications in optical communications, quantum technologies, and optical tweezers. Recently, they have attracted growing interest since they can be harnessed to detect peculiar helical dichroic effects in chiral molecular media and in magnetic nanostructures. In this work, we perform single-shot per position ptychography on a nanostructured object at a seeded free-electron laser, using extreme ultraviolet OAM beams of different topological charge orders ℓ generated with spiral zone plates. By controlling ℓ, we demonstrate how the structural features of OAM beam profiles determine an improvement of about 30% in image resolution with respect to conventional Gaussian beam illumination. This result extends the capabilities of coherent diffraction imaging techniques, and paves the way for achieving time-resolved high-resolution (below 100 nm) microscopy on large area samples.
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| 8. |
- Calfapietra, Carlo, et al.
(författare)
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Challenges in elevated CO2 experiments on forests
- 2010
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Ingår i: Trends in Plant Science. - : Elsevier BV. - 1360-1385. ; 15:1, s. 5-10
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Forskningsöversikt (refereegranskat)abstract
- Current forest Free Air CO2 Enrichment (FACE) experiments are reaching completion. Therefore, it is time to define the scientific goals and priorities of future experimental facilities. In this opinion article, we discuss the following three overarching issues (i) What are the most urgent scientific questions and how can they be addressed? (ii) What forest ecosystems should be investigated? (iii) Which other climate change factors should be coupled with elevated CO2 concentrations in future experiments to better predict the effects of climate change? Plantations and natural forests can have conflicting purposes for high productivity and environmental protection. However, in both cases the assessment of carbon balance and how this will be affected by elevated CO2 concentrations and the interacting climate change factors is the most pressing priority for future experiments.
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| 9. |
- De Angelis, Alessio, et al.
(författare)
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A Low-Cost Ultra-Wideband Indoor Ranging System
- 2009
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Ingår i: IEEE Transactions on Instrumentation and Measurement. - 0018-9456 .- 1557-9662. ; 58:12, s. 3935-3942
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents the development of a low-cost indoor ranging technique based on time-of-arrival (TOA) estimation, using short-pulse ultra-wideband (UWB) signals. The realized system includes two identical UWB transceiver devices, in which the receiver section is based on a tunnel diode detector and the pulse generation is performed by a common bipolar transistor driven in avalanche mode. An indirect measurement of the distance between the devices is obtained by measuring the frequency of the generated pulse train. A theoretical model of the system is described, and a statistical analysis is presented, including the closed-form evaluation of the Cramer-Rao lower bound (CRLB) on the distance estimation and showing the asymptotic statistical efficiency of the proposed estimators. Furthermore, the principle of operation of the realized system prototypes is described, along with some implementation issues. Finally, experimental results are shown and discussed.
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| 10. |
- De Angelis, Alessio, et al.
(författare)
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A low-cost ultra-wideband indoor ranging technique
- 2007
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Ingår i: 2007 24th IEEE Instrumentation and Measurement Technology Conference, VOLS 1-5. ; , s. 1308-1313
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Konferensbidrag (refereegranskat)abstract
- This paper presents the development of a low-cost indoor ranging technique based on Time-Of-Arrival (TOA) estimation, using Short-Pulse Ultra-Wideband (UWB) signals. The realized system includes two identical UWB transceiver devices, in which the receiver section is based on a tunnel diode detector and the pulse generation is performed by a common bipolar transistor driven in avalanche mode. An indirect measurement of the distance between the devices is obtained by measuring the frequency of the generated pulse train. A theoretical model of the system is described and a statistical analysis is presented, including the evaluation of the Cramer-Rao Lower Bound (CRLB) on the distance estimation. Furthermore the principle of operation of the realized system prototypes is described, along with some implementation issues. Finally experimental results are shown and discussed.
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| 11. |
- De Angelis, Alessio, et al.
(författare)
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A Vector Approach for Image Quality Assessment and Some Metrological Considerations
- 2009
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Ingår i: IEEE Transactions on Instrumentation and Measurement. - 0018-9456 .- 1557-9662. ; 58:1, s. 14-25
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Tidskriftsartikel (refereegranskat)abstract
- The main purpose of this paper is to present a metrology-based view of the image quality assessment (IQA) field. Three main topics are developed. First, the state of the art in the field of IQA is presented, providing a classification of some of the most important objective and subjective IQA methods. Then, some aspects of the field are analyzed from a metrological point of view, also through a comparison with the software quality measurement area. In particular, a statistical approach to the evaluation of the uncertainty for IQA objective methods is presented, and the topic of measurement modeling for subjective IQA methods is analyzed. Finally, a vector approach for full-reference IQA is discussed, with applications to images corrupted by impulse and Gaussian noise. For these applications, the vector root mean squared error (VRMSE) and fuzzy VRMSE are introduced. These vector parameters provide a possible way to overcome the main limitations of the mean-squared-error-based IQA methods.
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| 12. |
- De Angelis, Alessio, et al.
(författare)
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An Experimental UWB Distance Measurement System
- 2008
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Ingår i: 25th IEEE Instrumentation and Measurement Technology Conference, VOLS 1-5. ; , s. 1016-1020
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Konferensbidrag (refereegranskat)abstract
- This paper presents a distance-measuring system based on the accurate round-trip time-of-flight measurement of single Ultra-Wideband pulses, propagating between two transceiver devices. The architectures of two realized devices, referred to as master and slave, are described The master device implements the time-interval measuring function, by means of a Time-to-Digital Converter integrated circuit, while the slave acts as pulse repeater Both devices are designed for low-cost realization and low-power operations. This paper also presents and discusses some experimental results obtained from the system prototype. Finally, some numerical simulations results are shown, which could provide an explanation for the non-idealities in the observed distance-measuring behaviour of the system.
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| 13. |
- De Angelis, Alessio, et al.
(författare)
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Characterization and Modeling of an Experimental UWB Pulse-Based Distance Measurement System
- 2009
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Ingår i: IEEE Transactions on Instrumentation and Measurement. - 0018-9456 .- 1557-9662. ; 58:5, s. 1479-1486
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents a distance-measuring system based on the accurate round-trip time-of-flight measurement of single ultrawideband pulses propagating between two transceiver devices. The architectures of two realized devices, which are referred to as the master and the slave, are described. The master device implements the time-interval measuring function by means of a time-to-digital converter (TDC) integrated circuit, whereas the slave acts as a pulse repeater. Both devices are designed for low-cost realization and low-power operations. Furthermore, two pulse-detection modules are described based on signal-threshold and energy detection, respectively. This paper also presents and discusses some experimental results that are obtained from the system prototype. Finally, some numerical simulation results, which provide an explanation for the nonidealities in the observed distance-measuring behavior of the system, are shown.
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| 14. |
- De Angelis, Alessio, et al.
(författare)
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Experimental Comparison of Low-Cost Sub-Nanosecond Pulse Generators
- 2011
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Ingår i: IEEE Transactions on Instrumentation and Measurement. - 0018-9456 .- 1557-9662. ; 60:1, s. 310-318
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, six low-cost pulse generator devices having sub-nanosecond transition time are analyzed and compared. Some of the possible applications for these devices are also described, along with an overview of the different approaches for sub-nanosecond pulse generation. Furthermore, the architecture and principle of operation of the realized prototypes are explained. The considered pulse generation techniques are based on logic gates, Step-Recovery Diodes, and transistors driven in the avalanche region. Some experimental results obtained by using an equivalent-time sampling oscilloscope and a spectrum analyzer are shown and discussed, providing both a time-domain and a frequency-domain characterization of the prototypes. Finally, an approach for the generation of modulated pulses in the 6-GHz band (for ultra-wideband applications) is investigated, and experimental results are provided.
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| 15. |
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| 16. |
- De Angelis, Alessio, et al.
(författare)
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Image quality assessment : an overview and some metrological considerations
- 2007
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Ingår i: 2007 IEEE INTERNATIONAL WORKSHOP ON ADVANCED METHODS FOR UNCERTAINTY ESTIMATION IN MEASUREMENT. ; , s. 47-52
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Konferensbidrag (refereegranskat)abstract
- This paper presents the state of the art in the field of Image Quality Assessment (IQA), providing a classification of some of the most important objective and subjective IQA methods. Furthermore, some aspects of the field are analysed from a metrological point of view, also through comparison with the software quality measurement area. In particular a statistical approach to the evaluation of the uncertainty for IQA objective methods is presented and an example is provided. The topic of measurement modelling for subjective IQA methods is also analysed. Finally, a case study of images corrupted by impulse noise is discussed.
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| 17. |
- De Angelis, Alessio, et al.
(författare)
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Indoor positioning by ultra wide band radio aided inertial navigation
- 2010
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Ingår i: Metrology and Measurement Systems. - : Polish Academy of Sciences Chancellery. - 0860-8229. ; 17:3, s. 447-460
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Tidskriftsartikel (refereegranskat)abstract
- A research study aimed at developing a novel indoor positioning system is presented. The realized system prototype uses sensor fusion techniques to combine information from two sources: an in-house developed local Ultra-Wideband (UWB) radio-based ranging system and an inertial navigation system (INS). The UWB system measures the distance between two transceivers by recording the round-trip-time (RTT) of UWB radio pulses. Its principle of operation is briefly described, together with the main design features. Furthermore, the main characteristics of the INS and of the Extended Kalman Filter information fusion approach are presented. Finally, selected static and dynamic test scenario experimental results are provided. In particular, the advantages of the proposed information fusion approach are further investigated by means of a high dynamic test scenario.
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| 18. |
- De Angelis, Alessio, et al.
(författare)
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Performance Assessment of Chirp-Based Time Dissemination and Data Communications in Inductively Coupled Links
- 2017
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Ingår i: IEEE Transactions on Instrumentation and Measurement. - 0018-9456 .- 1557-9662. ; 66:9, s. 2474-2482
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Tidskriftsartikel (refereegranskat)abstract
- Advantages of inductively coupled links for short-range communications are well known. Recently, they gained popularity as a viable solution for wireless power transmission. Interesting to notice that data communication capability is required as well, mainly for coordinating the transfer process. In this paper, the authors address the use of chirp signaling over inductively coupled links for both time dissemination and data communications. Such an approach extends field of applications, including data acquisition and instrumentation that are used in industrial automation. The effectiveness of the proposed approach is verified with extensive simulations and using a proof-of-concept prototype. Despite the prototype simplicity, jitter on the synchronizing reference signal is in the order of few microseconds and the bit error rate, over a short distance, is negligible.
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| 19. |
- De Angelis, Nicola, et al.
(författare)
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Guided bone regeneration with and without a bone substitute at single post-extractive implants: 1-year post-loading results from a pragmatic multicentre randomised controlled trial.
- 2011
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Ingår i: European journal of oral implantology. - 1756-2406. ; 4:4, s. 313-25
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Tidskriftsartikel (refereegranskat)abstract
- To evaluate whether the adjunctive use of a bone substitute at immediate single implants placed in fresh extraction sockets with a residual buccal bone-to-implant gap of at least 1 mm could improve the aesthetic outcome of guided bone regeneration (GBR).Eighty patients requiring bone augmentation at a single immediate postextractive implant to improve the aesthetic outcome were randomly allocated to an augmentation procedure using a resorbable barrier alone (GBR group; 40 patients) or a bone substitute plus a resorbable barrier (GBR + BS group; 40 patients) according to a parallel group design at four different centres. Three to 4 months after implant placement/augmentation, implants were loaded with provisional or definitive single crowns. Outcome measures were implant failures, complications, aesthetics assessed using the pink esthetic score (PES), patient satisfaction and peri-implant marginal bone levels, recorded by blinded assessors. All patients were followed up to 1 year after loading.One patient dropped out from the GBR group. Seven (9%) implants failed: 2 (5%) in the GBR + BS group and 5 (12.5%) in the GBR group. Six minor complications occurred in the GBR + BS group versus 2 in the GBR group. These differences were not statistically significant. Just after implant placement/augmentation, mean bone levels were -0.21 mm at GBR + BS implants and -1.92 mm at GBR implants whereas at 1 year after loading they were -1.04 and -1.76, respectively. When comparing the two groups, GBR + BS implants had 0.70 mm more peri-implant marginal bone than GBR implants. Aesthetics was scored by a blinded assessor as statistically significantly better for the GBR + BS group. Patients were equally satisfied. There were no differences between centres regarding the clinical outcomes.The use of additional an organic bovine bone substitute (Endobon) with resorbable collagen barriers (OsseoGuard) in defects around post-extractive implant improves the aesthetic outcome, though single post-extractive implants might be at a higher risk for implant failures.
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| 20. |
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| 21. |
- Fischer, Hubertus, et al.
(författare)
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Reconstruction of millennial changes in dust emission, transport and regional sea ice coverage using the deep EPICA ice cores from the Atlantic and Indian Ocean sector of Antarctica
- 2007
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Ingår i: Earth and Planetary Science Letters. - : Elsevier BV. - 0012-821X. ; 260, s. 340-354
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Tidskriftsartikel (refereegranskat)abstract
- Continuous sea salt and mineral dust aerosol records have been studied on the two EPICA (European Project for Ice Coring inAntarctica) deep ice cores. The joint use of these records from opposite sides of the East Antarctic plateau allows for an estimate ofchanges in dust transport and emission intensity as well as for the identification of regional differences in the sea salt aerosolsource. The mineral dust flux records at both sites show a strong coherency over the last 150 kyr related to dust emission changes inthe glacial Patagonian dust source with three times higher dust fluxes in the Atlantic compared to the Indian Ocean sector of theSouthern Ocean (SO). Using a simple conceptual transport model this indicates that transport can explain only 40% of theatmospheric dust concentration changes in Antarctica, while factor 5–10 changes occurred. Accordingly, the main cause for the strong glacial dust flux changes in Antarctica must lie in environmental changes in Patagonia. Dust emissions, hence environmentalconditions in Patagonia, were very similar during the last two glacials and interglacials, respectively, despite 2–4 °C warmertemperatures recorded in Antarctica during the penultimate interglacial than today. 2–3 times higher sea salt fluxes found in bothice cores in the glacial compared to the Holocene are difficult to reconcile with a largely unchanged transport intensity and thedistant open ocean source. The substantial glacial enhancements in sea salt aerosol fluxes can be readily explained assuming sea iceformation as the main sea salt aerosol source with a significantly larger expansion of (summer) sea ice in the Weddell Sea than inthe Indian Ocean sector. During the penultimate interglacial, our sea salt records point to a 50% reduction of winter sea icecoverage compared to the Holocene both in the Indian and Atlantic Ocean sector of the SO. However, from 20 to 80 ka beforepresent sea salt fluxes show only very subdued millennial changes despite pronounced temperature fluctuations, likely due to thelarge distance of the sea ice salt source to our drill sites.
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| 22. |
- Nilsson, John-Olof, et al.
(författare)
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SIGNAL PROCESSING ISSUES IN INDOOR POSITIONING BY ULTRA WIDE BAND RADIO AIDED INERTIAL NAVIGATION
- 2009
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Ingår i: Proc. EUSIPCO2009. - : EURASIP. ; , s. 2161-2165
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Konferensbidrag (refereegranskat)abstract
- The difficulties and possibilities connected to indoor positioning suggest using several sources of navigational information. Apart from the signal processing of the individual sources this gives rise to the need for information fusion. This article aims at presenting and describing the signal processing methods and issues faced when constructing a navigation system based on a local ultra wide band (UWB) ranging system and an inertial navigation system (INS). The signal processing methods within the individual systems are described together with techniques for fusing the information from them. Finally, filtering results of experimental data is presented with expected convergence properties and positioning accuracy of below ±4 cm.
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| 23. |
- Pasku, Valter, et al.
(författare)
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A Magnetic Ranging Aided Dead-Reckoning Indoor Positioning System for Pedestrian Applications
- 2016
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Ingår i: 2016 IEEE INTERNATIONAL INSTRUMENTATION AND MEASUREMENT TECHNOLOGY CONFERENCE PROCEEDINGS. - : IEEE conference proceedings. - 9781467392204 ; , s. 1526-1531
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Konferensbidrag (refereegranskat)abstract
- This paper investigates the applicability of a developed magnetic ranging and positioning system (MPS) as a support for a dead reckoning inertial navigation system for pedestrian applications. The integrated system combines the complementary properties of the separate systems, operating over long periods of time and in cluttered indoor areas with partial non-line-of-sight conditions. The obtained results show that the proposed approach can effectively improve the coverage area of the MPS and the operation time with bounded errors of the dead reckoning based system.
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| 24. |
- Pasku, Valter, et al.
(författare)
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A Magnetic Ranging-Aided Dead-Reckoning Positioning System for Pedestrian Applications
- 2017
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Ingår i: IEEE Transactions on Instrumentation and Measurement. - : IEEE. - 0018-9456 .- 1557-9662. ; 66:5, s. 953-963
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Tidskriftsartikel (refereegranskat)abstract
- This paper investigates the applicability of a developed Magnetic Positioning System (MPS) as a support for a dead-reckoning inertial navigation system (DR-INS) for pedestrian applications. The integrated system combines the complementary properties of the separate systems, operating over long periods of time and in cluttered indoor areas with partial nonline-of-sight conditions. The obtained results show that the proposed approach can effectively improve the coverage area of the MPS and the operation time with bounded errors of the DR-INS. In particular, a solution that provides bounded position errors of 1-2 m over significantly long periods of time up to 45 min, in realistic indoor environments, is demonstrated. Moreover, system applicability is also shown in those scenarios where arbitrary orientations of the MPS mobile node are considered and an MPS position estimate is not available due to less than three distance measurements.
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| 25. |
- Ponzellini, Paolo, et al.
(författare)
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Plasmonic zero mode waveguide for highly confined and enhanced fluorescence emission
- 2018
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Ingår i: Nanoscale. - : Royal Society of Chemistry. - 2040-3364 .- 2040-3372. ; 10:36, s. 17362-17369
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Tidskriftsartikel (refereegranskat)abstract
- We fabricate a plasmonic nanoslot that is capable of performing enhanced single molecule detection at 10 μM concentrations. The nanoslot combines the tiny detection volume of a zero-mode waveguide and the field enhancement of a plasmonic nanohole. The nanoslot is fabricated on a bi-metallic film formed by the sequential deposition of gold and aluminum on a transparent substrate. Simulations of the structure yield an average near-field intensity enhancement of two orders of magnitude at its resonant frequency. Experimentally, we measure the fluorescence stemming from the nanoslot and compare it with that of a standard aluminum zero-mode waveguide. We also compare the detection volume for both structures. We observe that while both structures have a similar detection volume, the nanoslot yields a 25-fold fluorescence enhancement.
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| 26. |
- Santoni, Francesco, et al.
(författare)
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Calibration and Characterization of a Magnetic Positioning System Using a Robotic Arm
- 2019
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Ingår i: IEEE Transactions on Instrumentation and Measurement. - : IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC. - 0018-9456 .- 1557-9662. ; 68:5, s. 1494-1502
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, a robotic arm moving along a user-defined trajectory is used to calibrate a short-range magnetic positioning system (MPS). Such system estimates the position and attitude of an active transmitting coil by measuring the induced voltage on a set of fixed receiving coils, with known position and orientation. This estimate is obtained by solving an optimization problem that can be decomposed into a linear and a reduced nonlinear problem. Then, a Kalman Filter is used to process the estimated positions and obtain smooth trajectories. Data acquisition and processing are performed in real time by the MPS. In this context, the robotic arm is used to provide ground truth, i.e., to move the active coil along a known trajectory, while simultaneously the MPS estimates the position of the active coil. Such ground-truth information is then used to calibrate the MPS and improve its accuracy. To align the robotic arm with the MPS, a preliminary calibration procedure of the robot is performed. Then, a wide ground-truth trajectory is used to estimate the calibration parameters of the MPS itself, namely, the positions and orientation of the fixed coils. To validate the efficiency of the calibration procedure, the accuracy of the MPS is evaluated across several trajectories. The results show that the mean positioning error is less than 3 mm. Finally, an on-the-fly calibration method simultaneously estimating positions and attitudes of both the active coil and all the receivers is investigated.
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| 27. |
- Zambrana-Puyalto, Xavier, et al.
(författare)
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Site-selective functionalization of plasmonic nanopores for enhanced fluorescence emission rate and Förster resonance energy transfer
- 2019
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Ingår i: Nanoscale Advances. - : Royal Society of Chemistry. - 2516-0230. ; 1:6, s. 2454-2461
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Tidskriftsartikel (refereegranskat)abstract
- In this work, we use a site-selective functionalization strategy to decorate plasmonic nanopores with fluorescent dyes. Using an easy and robust fabrication method, we manage to build plasmonic rings on top of dielectric nanotubes with different inner diameters. The modulation of the dimension of the nanopores allows us to tailor their field confinement and their Purcell factor in the visible spectral range. In order to investigate how the changes in geometry influence the fluorescence emission rate efficiency, thiol-conjugated dyes are anchored on the plasmonic ring, thus forming a functional nanopore. We study the lifetime of ATTO 520 and ATTO 590 attached in two different configurations: single dye and FRET pair. For the single dye configuration, we observe that the lifetime of both single dyes decreases as the size of the nanopore is reduced. The smallest nanopores yield an experimental Purcell factor of 6. For the FRET pair configuration, we measure two regimes. For large nanopore sizes, the FRET efficiency remains constant. Whereas for smaller sizes, the FRET efficiency increases from 30 up to 45% with a decrease of the nanopore size. These findings, which have been supported by numerical simulations, may open new perspectives towards energy transfer engineering in plasmonic nanopores with potential applications in photonics and biosensing, in particular in single-molecule detection and sequencing.
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