Search

Publisher’s Note: This paper, originally published on 12 April 2021, was withdrawn on 5 May 2021 per author request.

There are significant challenges in global healthcare delivery at the moment. Some countries have abundant services, but are stuck with a rather nimble and expensive system that focuses on incremental innovations. Other geographies are still in need of basic tools, infrastructure and require completely different, inexpensive, and with that more disruptive solutions to satisfy their healthcare needs. Next Generation Healthcare systems with a focus on prevention / early detection and pro-active therapy will employ exponential technologies (AI, Big Data, Blockchain, Sensor Technology, Synthetic Biology, Tissue Engineering, Robotics, 3D Printing, ...) that will surely lead to significant changes in the way we experience, think about, and deliver healthcare and in which a digitally empowered patient will play a more important role. In the coming years/decades we will experience a shift from the current SICK-CARE provision to real HEALTHCARE to a focus on personal HEALTH, supported by an integration of patient generated health data with other external diagnostic and therapeutic data components creating a digital health twin as a base for prevention and patient centered precision medicine. Education and training of Biomedical Engineers needs to be adjusted to these developments focussing on solving unmet clinical needs, which requires a solid understanding of current health problems (regional, global), future technologies, economic realities and global health markets. The paper will present and discuss some of these future global innovation needs and the subsequent need for a change in the biomedical engineering curriculum that needs to include learning- (creativity, critical thinking, collaboration) and life skills (flexibility, leadership, social), as well as basic economic and entrepreneurial training — all of which are currently not taught or emphasized.

Graphene paper has diverse applications in printed circuit board electronics, bioassays, 3D cell culture, and biosensing. Although development of nanometal-graphene hybrid composites is commonplace in the sensing literature, to date there are only a few examples of nanometal-decorated graphene paper for use in biosensing. In this manuscript, we demonstrate the synthesis and application of Pt nano cauliflower-functionalized graphene paper for use in electrochemical biosensing of small molecules (glucose, acetone, methanol) or detection of pathogenic bacteria ( Escherichia coli O157:H7). Raman spectroscopy, scanning electron microscopy and energy dispersive spectroscopy were used to show that graphene oxide deposited on nanocellulose crystals was partially reduced by both thermal and chemical treatment. Fractal platinum nanostructures were formed on the reduced graphene oxide paper, producing a conductive paper with an extremely high electroactive surface area, confirmed by cyclic voltammetry and electrochemical impedance spectroscopy. To show the broad applicability of the material, the platinum surface was functionalized with three different biomaterials: 1) glucose oxidase (via chitosan encapsulation); 2) a DNA aptamer (via covalent linking), or 3) a chemosensory protein (via his linking). We demonstrate the application of this device for point of care biosensing. The detection limit for both glucose (0.08 ± 0.02 μM) and E. coli O157:H7 (1.3 ± 0.1 CFU mL -1 ) were competitive with, or superior to, previously reported devices in the biosensing literature. The response time (6 sec for glucose and 10 min for E. coli ) were also similar to silicon biochip and commercial electrode sensors. The results demonstrate that the nanocellulose-graphene-nanoplatinum material is an excellent paper-based platform for development of electrochemical biosensors targeting small molecules or whole cells for use in point of care biosensing.

Roughness of a paper surface is particularly important in paper and board destined to be printed. Surfaces are often coated and the amount of coating and method of application used depends on the roughness of the base paper. We present a method of measure of the roughness of the paper based in the analysis of speckle pattern on the surface. Images are captured by means of a simple configuration using a laser and a camera CCD. Then, we apply digital image processing using the co-occurrence matrix, so this method can be considered as a non-contact surface profiling method, that can be used online.

International audience; Dirty Paper Trellis Codes (DPTC) watermarking, published in 2004, is a very efficient high rate scheme. Nevertheless, it has two strong drawbacks: its security weakness and its CPU computation complexity. We propose an embedding space at least as secure and a faster embedding. The embedding space is built on the projections of some wavelet coefficients onto secret carriers. It keeps a good security level and has also good psycho-visual properties. The embedding is based on a dichotomous rotation in the Cox, Miller and Boom Plane. It gives better performances than previous fast embedding approaches. Four different attacks are performed and revealed good robustness and rapidity performances.

The paper industry has long had a need to better understand and control its papermaking process upstream, specifically at the wet end in the forming section of a paper machine. A vision-based system is under development that addresses this need by automatically measuring and interpreting the pertinent paper web parameters at the wet end in real time. The wet-end characterization of the paper web by a vision system involves a four-dimensional measurement of the slurry in real time. These measurements include the two-dimensional spatial information, the intensity profile, and the depth profile. This paper describes the real-time depth profile measurement system for the high-speed moving slurry. A laser line-based measurement method is used with a high-speed programmable camera to directly measure slurry height. The camera is programmed with a profile algorithm, producing depth data at fast sampling rates. Analysis and experimentation have been conducted to optimize the system for the characteristics of the slurry and laser line image. On-line experimental results are presented.

The UK National Quantum Technology Hub in Sensors and Metrology is one of four flagship initiatives in the UK National of Quantum Technology Program. As part of a 20-year vision it translates laboratory demonstrations to deployable practical devices, with game-changing miniaturized components and prototypes that transform the state-of-the-art for quantum sensors and metrology. It brings together experts from the Universities of Birmingham, Glasgow, Nottingham, Southampton, Strathclyde and Sussex, NPL and currently links to over 15 leading international academic institutions and over 70 companies to build the supply chains and routes to market needed to bring 10–1000x improvements in sensing applications. It seeks, and is open to, additional partners for new application development and creates a point of easy open access to the facilities and supply chains that it stimulates or nurtures.

Many infectious diseases, as well as some cancers, that affect global health are most accurately diagnosed through nucleic acid amplification and detection. There is a great need to simplify nucleic acid-based assay systems for use in global health in low-resource settings as well as in settings that do not have convenient access to laboratory staff and equipment such as doctors’ offices and home care settings. In developing countries, unreliable electric power, inadequate supply chains, and lack of maintenance for complex diagnostic instruments are all common infrastructure shortfalls. Many elements of instrument-free, disposable, nucleic acid amplification assays have been demonstrated in recent years. However, the problem of instrument-free,1 low-cost, temperature-controlled chemical heating remains unsolved. In this paper we present the current status and results of work towards developing disposable, low-cost, temperature-controlled heaters designed to support isothermal nucleic acid amplification assays that are integrated with a two-dimensional paper network. Our approach utilizes the heat generated through exothermic chemical reactions and controls the heat through use of engineered phase change materials to enable sustained temperatures required for nucleic acid amplification. By selecting appropriate exothermic and phase change materials, temperatures can be controlled over a wide range, suitable for various isothermal amplification methods, and maintained for over an hour at an accuracy of +/- 1°C.

Understanding the properties of paper fibers and paper fiber bonds can be really significant in improving the quality of paper. The problem in gathering measurement data from individual paper fibers is the lack of reliable and efficient research instruments. Also, without automation the yield of experiments will be low and the results will depend on the skills of the operator. This paper presents an image-based method to automatically detect the endpoints of paper fibers. The method will be utilized in automatic control of a novel and tailor-made paper fiber manipulation and measurement platform. Performance of the method is extremely promising with adequate speed and very accurate results. acceptedVersion

Lattice codes and quantization-based techniques have received considerable attention as a method of digital watermarking with side information. However, these algorithms are also recognized to be highly sensitive to common signal processing primitives such as valuemetric scaling, e.g. changes in volume of a song, or re-quantization, e.g. JPEG compression. Hence, it is reasonable to investigate alternative codes which may offer the potential for superior performance. In previous work, we designed a new class of codes, called dirty paper trellis codes (DPTC), which are by construction immune to valuemetric scaling. Although DPTC have shown themselves to be resistant to certain classes attacks, the trellises were generated randomly, thus leading to suboptimal codes. In this paper, Ungerboeck's work on trellis coded modulation (TCM) is exploited to significantly improve the performance of the DPTC. Experimental results show that the resulting trellises significantly outperform the original design.

Epilepsy is characterized by paroxysmal transient disturbances of the electrical activity of the brain. Symptoms are manifested as impairment of motor, sensory, or psychic function with or without loss of consciousness or convulsive seizures. This paper presents an initial post-operative heat transfer analysis of surgery performed on a 41 year-old man with medically intractable Epilepsy. The surgery involved tumor removal and the resection of adjacent epileptogenic tissue. Electrocorticography was performed before resection. Cold saline was applied to the resulting interictal spike foci resulting in transient, complete cessation of spiking. A transient one dimensional semi-infinite finite element model of the surface of the brain was developed to simulate the surgery. An approximate temperature distribution of the perfused brain was developed by applying the bioheat equation. The model quantifies the surface heat flux reached in achieving seizure cessation to within an order of magnitude. Rat models have previously shown that the brain surface temperature range to rapidly terminate epileptogenic activity is 20-24°C. The developed model predicts that a constant heat flux of approximately -13,000W/m 2 , applied at the surface of the human brain, would achieve a surface temperature in this range in approximately 3 seconds. A parametric study was subsequently performed to characterize the effects of brain metabolism and brain blood perfusion as a function of the determined heat flux. The results of these findings can be used as a first approximation in defining the specifications of a cooling device to suppress seizures in human models.

Microspheres possess high quality factor morphology-dependent resonances, i.e., whispering gallery modes. These resonances have narrow linewidths necessary for applications to compact optoelectronic devices for wavelength division multiplexing. The morphology dependent resonances have high quality factors of 104 and 105 with channel spacings of 0.14 nm in glass and 0.05 nm in silicon microspheres.

Polymer helices with submicron dimensions have been fabricated from a variety of isotropic and liquid crystalline polymers with storage moduli ranging from 38MPa to 1.9GPa (measured at 1Hz, room temperature). These helices are made using a double templating process, in which a thin film comprised of independent helical structures deposited using glancing angle deposition (GLAD) acts as the master. In our process the 'positive' structure of the master is copied into a polymer 'negative', which then itself acts as a template for the final film of polymer helices. Liquid crystalline polymers are of particular interest for use in MEMS because highly ordered liquid crystalline polymers can be actuated by exposing them to a stimulus (such as heat) that causes a decrease in order, leading to a reversible, macroscopic change in shape. The phase behavior, optical properties, and mechanical properties of planar aligned monoacrylate liquid crystalline polymers with varying crosslinker content are investigated, in order to determine the composition that will yield the largest deformations upon heating. We find that films with the lowest crosslinker content investigated (2.5%) undergo the largest reduction in birefringence as they are heated, corresponding to a loss in order. However, we also observe that the films with the highest crosslinker content investigated (10%) undergo the largest physical deformation upon heating. SEM images illustrating the deformation of liquid crystalline polymer helices as they are heated are also presented.

Injection strategies have been employed in the field of fluidic MEMS using piezo electric or thermal actuators. A very popular application for such technology is inkjet printing. Largely this technology is used to produce droplets of fluid in air; the aim of this investigation is to produce an injection device for the precise dispensing of nanolitre volumes of fluid. A novel technique for dispensing fluid using superparamagnetic beads has been investigated. The beads used (Dynal Biotech) contain a homogeneous dispersion of Fe. This is an investigation using silicon and Pyrex fabricated micro channels with smaller dimensions, such that the dimensions will be similar to those which will be used to produce a pipette device. Here results are presented using these fabricated micro channels, where the effects of using differently sized bead plugs and varying velocities are examined. The results follow our proposed theory; further analysis is required to determine the operation of a bead plug during all states of movement.

The growing interest in biological micro-array and Lab-on-Chip (LOC) is justified by the possibility of reducing the sample volume, processing time and costs. By means microfluidics seems to be the prevalent tool for the integration of manifold processes in miniaturized devices. Anyway at a sub-millimeter scale the liquid behavior is affected by geometric confinement and wetting properties. In order to confine the liquid sample inside the LOC buried channels we have performed the sealing by poly(dimethylsiloxane)~(PDMS), a silicon-based bi-component elastomer. The filling dynamics changes at changing of the polymer mixing ratio of the pre-polymer and the curing agent. In fact, a different concentration of cross-linker modifies the elastic, adhesion and wettability properties of the cover-slip© (2005) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

We present a controlled, well-defined pattern replication of a micrometer template driven by a surface free energy lithographic technique, realized by molecular aggregation in dewetting conditions and by confining the liquid solution with geometric boundaries. The presented technique has allowed the fabrication of light-emitting devices, and in particular the realization of OLEDs with an array of addressable pixels.

The concept of optical coherence tomography (OCT) for high-resolution imaging of tissues in vivo is introduced. Analytical and numerical models for describing and understanding the light propagation in samples imaged by OCT systems are presented. An analytical model for calculating the OCT signal based on the extended Huygens-Fresnel principle and valid both for single and multiple scattering regimes is outlined. From this model, an algorithm for extracting tissue optical properties for multi-layered tissues is derived. The algorithm is first verified for various optical properties and geometries using solid phantoms and numerical simulations. The applicability of the algorithm for extraction of tissue optical properties is then demonstrated for vascular tissue samples ex vivo. With the use of data from numerical phantoms, the validity of the OCT extraction algorithm for a two-layer geometry is further supported. It is concluded that by using optical properties extracted from OCT images of human tissues, the clinical utility of OCT imaging can be substantially increased.

A novel uncooled long-wave infrared imaging technology with optical readout is proposed and developed targeted for low cost thermal imaging applications. This technology uses the thermo-optic effect in a semiconductor to detect infrared signals rather than the thermal-resistance effect used in traditional microbolometers. The key component of the imager, the focal plane array, is made up of thermally tunable thin film filter membrane pixels. Each thermal pixel acts as a wavelength translator, converting far infrared radiation signals into near infrared signals which are then detectable by off-the-shelf CCD or CMOS cameras. This approach utilizes optical filter and MEMS technologies, to build a low-cost passive long wavelength infrared focal plane array without electrical leads or active cooling. Within one year since the commencement, NETD values of 0.28K in a 160x120 array operating at 22Hz video frame rate have been achieved without temperature control.

In silicon, direct electronic transitions leading to light emission have a low probability of occurrence due to the momentum mismatch between upper and lower electronic levels. Until recently, this had prevented the realization of the long waited silicon optical amplifier and laser. Raman scattering, which describes the interactions of light with vibrational levels, can be used as a way to bypass the indirect band structure of silicon and to obtain amplification and lasing. The Raman approach is very appealing because device can be made in pure silicon with a spectrum that is widely tuneable though the pump laser wavelength. While a new research topic, amplifiers with pulsed gain of 20dB and CW gain of 3 dB have already been demonstrated. Using parametric Raman coupling, wavelength conversion from 1550nm to 1300nm has been achieved. A distinguishing feature of silicon Raman devices, compared to fiber devices, is the electronic modulation capability. By integrating a p-n junction with the silicon gain medium, electrically switched lasers and amplifiers have already been demonstrated. These have many exciting applications. For example, the laser can be directly modulated to transmit data, and can be part of a silicon optoelectronic integrated circuit. At the same time, electrically switched amplifiers represent loss-less optical modulators.© (2005) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

We discuss the stationary states of a model economy in which $N$ heterogeneous adaptive consumers purchase commodity bundles repeatedly from $P$ sellers. The system undergoes a transition from an inefficient to an efficient state as the number of consumers increases. In the latter phase, however, price fluctuations may be much larger than in the inefficient regime. Results from dynamical mean-field theory obtained for $N\to\infty$ compare fairly well with computer simulations.

A wide variety of dissipative and fluctuation problems involving a quantum system in a heat bath can be described by the independent-oscillator (IO) model Hamiltonian. Using Heisenberg equations of motion, this leads to a generalized quantum Langevin equation (QLE) for the quantum system involving two quantities which encapsulate the properties of the heat bath. Applications include: atomic energy shifts in a blackbody radiation heat bath; solution of the problem of runaway solutions in QED; electrical circuits (resistively shunted Josephson barrier, microscopic tunnel junction, etc.); conductivity calculations (since the QLE gives a natural separation between dissipative and fluctuation forces); dissipative quantum tunneling; noise effects in gravitational wave detectors; anomalous diffusion; strongly driven quantum systems; decoherence phenomena; analysis of Unruh radiation and entropy for a dissipative system.

Reaction dynamics involving subdiffusive species is an interesting topic with only few known results, especially when the motion of different species is characterized by different anomalous diffusion exponents. Here we study the reaction dynamics of a (sub)diffusive particle surrounded by a sea of (sub)diffusive traps in one dimension. Under some reasonable assumptions we find rigorous results for the asymptotic survival probability of the particle in most cases, but have not succeeded in doing so for a particle that diffuses normally while the anomalous diffusion exponent of the traps is smaller than 2/3.© (2005) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

An efficient multiplexing method for fiber Bragg grating sensors based on a broadband mode-locked laser source and interferometric interrogation is described. The system has the capability to interrogate several hundred fiber Bragg grating sensors on a single fiber, whilst achieving sub-microstrain resolution over bandwidths greater than 100 kHz. A demonstration system with 8 sensors is presented, which achieves strain resolutions less than 213 n epsilon/Hz(1/2) up to 100 Hz.

A direct comparison between continuous and discrete forms of analysis of control and stability is investigated theoretically and numerically. We demonstrate that the continuous method provides a more energy-efficient means of controlling the switching of a periodically-driven class-B laser between its stable and unstable pulsing regimes. We provide insight into this result using the close correspondence that exists between the problems of energy-optimal control and the stability of a steady state.

We show how the semiclassical Langevin method can be extended to calculations of higher-than-second cumulants of noise. These cumulants are affected by indirect correlations between the fluctuations, which may be considered as "noise of noise." We formulate simple diagrammatic rules for calculating the higher cumulants and apply them to mesoscopic diffusive contacts and chaotic cavities. As one of the application of the method, we analyze the frequency dependence of the third cumulant of current in these systems and show that it contains additional peculiarities as compared to the second cumulant. The effects of environmental feedback in measurements of the third cumulant are also discussed in terms of this method.

Fluctuations in diversity and extinction sizes are discussed and compared for two dierent, individual-basedmodels of biological coevolution. Both models display power-law distributions for various quantities of evolu-tionary interest, such as the lifetimes of individual species, the quiet periods between evolutionary upheavalslarger than a given cuto, and the sizes of extinction ev ents. Time series of the diversity and measures of thesize of extinctions give rise to ”icker noise. Surprisingly, the power-law behaviors of the probability densities ofquiet periods in the two models dier, while the distributions of the lifetimes of individual species are the same.Keywords: Biological evolution, Coevolution, Flicker noise, Fluctuations, Power-law distributions 1. INTRODUCTION Biological evolution presents many problems concerning highly nonlinear, nonequilibrium systems of interactingentities that are well suited for study by methods from statistical mechanics. An excellent review of this rapidlygrowing “eld is found in Ref. 1. Among these problems are those concerned with coevolution :thesimulta-neous evolution of many species, whose mutual interactions produce a constantly changing Þtness landscape .Throughout this process, new species are created and old species go extinct. A question that is still debated inevolutionary biology is whether evolu tion on the macroscaleproceeds gradually or in “ts and starts, as suggestedby Eldredge and Gould.

The cornerstone of Boltzmann-Gibbs ($BG$) statistical mechanics is the Boltzmann-Gibbs-Jaynes-Shannon entropy $S_{BG} \equiv -k\int dx f(x)\ln f(x)$, where $k$ is a positive constant and $f(x)$ a probability density function. This theory has exibited, along more than one century, great success in the treatment of systems where short spatio/temporal correlations dominate. There are, however, anomalous natural and artificial systems that violate the basic requirements for its applicability. Different physical entropies, other than the standard one, appear to be necessary in order to satisfactorily deal with such anomalies. One of such entropies is $S_q \equiv k (1-\int dx [f(x)]^q)/(1-q)$ (with $S_1=S_{BG}$), where the entropic index $q$ is a real parameter. It has been proposed as the basis for a generalization, referred to as {\it nonextensive statistical mechanics}, of the $BG$ theory. $S_q$ shares with $S_{BG}$ four remarkable properties, namely {\it concavity} ($\forall q>0$), {\it Lesche-stability} ($\forall q>0$), {\it finiteness of the entropy production per unit time} ($q \in \Re$), and {\it additivity} (for at least a compact support of $q$ including $q=1$). The simultaneous validity of these properties suggests that $S_q$ is appropriate for bridging, at a macroscopic level, with classical thermodynamics itself. In the same natural way that exponential probability functions arise in the standard context,power-law tailed distributions, even with exponents {\it out} of the L\'evy range, arise in the nonextensive framework. In this review, we intend to show that many processes of interest in economy, for which fat-tailed probability functions are empirically observed, can be described in terms of the statistical mechanisms that underly the nonextensive theory.

The current noise of a voltage biased interacting quantum wire adiabatically connected to metallic leads is computed in presence of an impurity in the wire. We find that in the weak backscattering limit the Fano factor characterizing the ratio between shot noise and backscattering current crucially depends on the noise frequency relative to the ballistic frequency v_F/gL, where v_F is the Fermi velocity, g the Luttinger liquid interaction parameter, and L the length of the wire. In contrast to chiral Luttinger liquids, the noise is not only due to the Poissonian backscattering of fractionally charged quasiparticles at the impurity, but also depends on Andreev-type reflections of plasmons at the contacts, so that the frequency dependence of the noise needs to be analyzed to extract the fractional charge e*=e g of the bulk excitations. We show that the frequencies needed to see interaction effects in the Fano factor are within experimental reach.

A brief overview is given of the research activities in the Quantum Optics Group at Caltech related to the new science of Quantum Information.

We analyze periodically driven bistable systems by two different approaches. The first approach is a linearization of the stochastic Langevin equation of our system by the response on small external force. The second one is based on the Gaussian approximation of the kinetic equations for the cumulants. We obtain with the first approach the signal power amplification and output signal-to-noise ratio for a model piece-wise linear bistable potential and compare with the results of linear response approximation. By using the second approach to a bistable quartic potential, we obtain the set of nonlinear differential equations for the first and the second cumulants.© (2005) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

We consider the following general problem of applied stochastic nonlinear dynamics. We observe a time series of signals y(t) = y(t0+hn) corrupted by noise. The actual state and the nonlinear vector field of the dynamical system is not known. The question is how and with what accuracy can we determine x(t) and functional form of f(x). In this talk we discuss a novel approach to the solution of this problem based on the application of the path-integral approach to the full Bayesian inference. We demonstrate a reconstruction of a dynamical state of a system from corrupted by noise measurements. Next we reconstruct the corresponding nonlinear vector field. The emphasis are on the theoretical analysis. The results are compared with the results of earlier research.© (2005) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Preliminary results are reported from a research project analysing congestive heart failure in terms a stochastic coupled-oscillator model of the cardiovascular system. Measurements of blood flow by laser Doppler flowmetry (LDF) have been processed by use of the wavelet transform to separate its oscillatory components, which number at least five. Particular attention was concentrated on the frequency content near 0.01 Hz, which is known to be associated with endothelial function. The LDF was carried out in conjunction with iontophoretically administered acetylcholine (ACh) and sodium nitroprusside (SNP) in order to evaluate endothelial reactivity. Measurements were made on 17 congestive heart failure (CHF) patients (a) on first diagnosis, and (b) again several weeks later after their treatment with a β-blocker had been stabilised. The results of these two sets of measurements are being compared with each other, and with data from an age and sex-matched group of healthy controls. It is confirmed that endothelial reactivity is reduced in CHF patients, as compared to healthy controls, and it is found that one effect of the Beta-blocker is to ameliorate the loss of endothelial function in CHF. The implications of these results are discussed.

We review recent advances in Yb fiber lasers and amplifiers for high power short pulse systems. We go on to describe associated recent developments in fiber components for use in such systems. Examples include microstructured optical fibers for pulse compression and supercontinuum generation, and advanced fiber grating technology for chirped-pulse amplifier systems.

Fil: Bragas, Andrea Veronica. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Oficina de Coordinacion Administrativa Ciudad Universitaria. Instituto de Fisica de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Fisica de Buenos Aires; Argentina

The operation of the Hot Electron Light Emitting and Lasing in Semiconductor Heterostructure -- Vertical Cavity Surface Emitting Laser (HELLISH-VCSEL) devices is based on hot carrier transport parallel to the layers of Ga1-xAlxAs p-n junction. It is therefore a field - effect device and the light emission from the device is independent of the polarity of the applied voltage. In this study, we present the temperature dependence of the operational characteristics of the device. Experimental studies comprising of the measurements of the I-V characteristics, electroluminescence, reflectivity, and temperature dependent light-applied electric field (L-F) characteristics are conducted to find the optimum operating temperature of the device.

As the Internet continues to expand into new application domains, there is growing demand for differentiated services that provide varying degrees of Quality of Service (QoS). Until recently, the approach for service differentiation in the Internet has focused on providing QoS guarantees to individual traffic flows. This per-flow model has not been widely embraced, largely due to the vast amount of state information that needs to be maintained in the network. As a consequence, the network community is currently redefining the notion of QoS for the Internet, leading to a new service model where guarantees are made to aggregate flows, rather than to individual flows. The notions of aggregate QoS which are being defined, e.g., by the Differentiated Services (DiffServ) working group in the IETF, are very different from traditional networking concepts and require novel algorithms for traffic control and provisioning. In our work in this area we seek to derive fundamental insights into the nature and delivery of QoS to traffic aggregates, i.e. aggregate QoS. A central feature of service models for aggregate QoS is that there is no requirement for users to specify the composition or the destination of traffic. This significantly complicates the provisioning of network resources and suggests that new, feedback-intensive traffic control algorithms must be developed to mitigate uncertainty about network loading. At present there is little or no theory available to guide the development of such algorithms. In this paper we lay out a research agenda for illuminating the fundamental issues associated with QoS for aggregate traffic. By providing a theoretical reference frame for aggregate QoS, one which provides tools and techniques for congestion control, capacity provisioning, and admission control, we complement ongoing standardization efforts for differentiated services in the Internet.

Ultrafast all-optical, fibre optic switches are of great interest as all-optical signal processing elements in telecommunication systems and as passive mode-lockers for all-fibre mode-lock lasers. We describe the operation and characteristics of two such switches, the conventional and amplifying Sagnac switch, and describe the use of these components in a recently developed, passive, self-starting, mode-locked erbium doped fibre laser capable of the generation of solitons with durations as short as 320 femtoseconds.

Significance: The recently reported solvent-based optical clearing method FDISCO can preserve various fluorescent signals very well. However, the strict low-temperature storage condition of FDISCO is not conducive to long-time or repetitive imaging usually conducted at room temperature. Therefore, it is important to solve the contradiction between fluorescence preservation and imaging condition. Aim: We develop a modified FDISCO clearing method, termed FDISCO+, to change the preservation condition from low temperature to room temperature. Approach: Two alternative antioxidants were screened out to effectively inhibit the peroxide generation in the clearing agent at room temperature, enabling robust fluorescence preservation of cleared samples. Results: FDISCO+ achieves comparable fluorescence preservation with the original FDISCO protocol and allows long-time storage at room temperature, making it easier for researchers to image and preserve the samples. Conclusions: FDISCO+ is expected to be widely used due to its loose operation requirements.

Significance: The reliability of functional near-infrared spectroscopy (fNIRS) measurements is reduced by systemic physiology. Short-channel regression algorithms aim at removing systemic “noise” by subtracting the signal measured at a short source–detector separation (mainly scalp hemodynamics) from the one of a long separation (brain and scalp hemodynamics). In literature, incongruent approaches on the selection of the optimal regressor signal are reported based on different assumptions on scalp hemodynamics properties. Aim: We investigated the spatial and temporal distribution of scalp hemodynamics over the sensorimotor cortex and evaluated its influence on the effectiveness of short-channel regressions. Approach: We performed hand-grasping and resting-state experiments with five subjects, measuring with 16 optodes over sensorimotor areas, including eight 8-mm channels. We performed detailed correlation analyses of scalp hemodynamics and evaluated 180 hand-grasping and 270 simulated (overlaid on resting-state measurements) trials. Five short-channel regressor combinations were implemented with general linear models. Three were chosen according to literature, and two were proposed based on additional physiological assumptions [considering multiple short channels and their Mayer wave (MW) oscillations]. Results: We found heterogeneous hemodynamics in the scalp, coming on top of a global close-to-homogeneous behavior (correlation 0.69 to 0.92). The results further demonstrate that short-channel regression always improves brain activity estimates but that better results are obtained when heterogeneity is assumed. In particular, we highlight that short-channel regression is more effective when combining multiple scalp regressors and when MWs are additionally included. Conclusion: We shed light on the selection of optimal regressor signals for improving the removal of systemic physiological artifacts in fNIRS. We conclude that short-channel regression is most effective when assuming heterogeneous hemodynamics, in particular when combining spatial- and frequency-specific information. A better understanding of scalp hemodynamics and more effective short-channel regression will promote more accurate assessments of functional brain activity in clinical and research settings., Neurophotonics, 7 (03)

Over the past five years, Switzerland has undergone major changes in the field of photonics. Thanks to a well-positioned photonics industry and dedicated professional associations, new milestones were set in the area of training and further education, but also in research and development. The main reason for the shortage of skilled workers in Switzerland was identified as the lack of education for qualified photonics engineers at bachelor and master level. Some years ago, the majority of the Swiss photonics companies syndicated under the patronage of Swissmem as its Photonics Division. In 2015 the members defined their requirements for young skilled workers and prepared a position paper "Bachelor in Photonics" in which Universities of Applied Sciences (UAS) were specifically asked to offer application-oriented bachelor programs. The NTB with its long tradition in photonics R&D decided to go for such a program. A team developed a curriculum for a photonics profile and implemented it as part of the “Bachelor in Systems Engineering”. In autumn 2018 the first bachelor students graduated in photonics and were ready for an industrial career. The next step on the education roadmap in Switzerland was a specific profile in photonics as part of a nationwide Master Program in Engineering (MSE) for bachelor graduates of UAS. Here again the momentum came from the Swiss photonics industry. The planning and implementation of this unique master program is currently underway and is scheduled to start in September 2020.

The goal of understanding the architecture of neural circuits at the synapse level with a brain-wide perspective has powered the interest in high-speed and large field-of-view volumetric imaging at subcellular resolution. Here, we developed a method combining tissue expansion and light-sheet fluorescence microscopy to allow extended volumetric super resolution high-speed imaging of large mouse brain samples. We demonstrate the capabilities of this method by performing two color fast volumetric super resolution imaging of mouse CA1 and dentate gyrus molecular-, granule cell-, and polymorphic layers. Our method enables an exact evaluation of granule cell and neurite morphology within the context of large cell ensembles spanning several orders of magnitude in resolution. We found that imaging a brain region of 1 mm 3 in super resolution using light-sheet fluorescence expansion microscopy is about 17-fold faster than imaging the same region by a current state-of-the-art high-resolution confocal laser scanning microscope.