Exciting Areas Research Articles

Control of single photon emitters in semiconductor nanowires by surface acoustic waves

We report on an experimental study into the effects of surface acoustic waves on the optical emission of dot-in-a-nanowire heterostructures in III-V material systems. Under direct optical excitation, the excitonic energy levels in III-nitride dot-in-a-nanowire heterostructures oscillate at the acoustic frequency, producing a characteristic splitting of the emission lines in the time-integrated photoluminescence spectra. This acoustically induced periodic tuning of the excitonic transition energies is combined with spectral detection filtering and employed as a tool to regulate the temporal output of anti-bunched photons emitted from these nanowire quantum dots. In addition, the acoustic transport of electrons and holes along a III-arsenide nanowire injects the electric charges into an ensemble of quantum dot-like recombination centers that are spatially separated from the optical excitation area. The acoustic population and depopulation mechanism determines the number of carrier recombination events taking place simultaneously in the ensemble, thus allowing control of the anti-bunching degree of the emitted photons. The results presented are relevant for the dynamic control of single photon emission in III-V semiconductor heterostructures.

Quantum critical behavior in the asymptotic limit of high disorder in the medium entropy alloy NiCoCr0.8

The behavior of matter near a quantum critical point is one of the most exciting and challenging areas of physics research. Emergent phenomena such as high-temperature superconductivity are linked to the proximity to a quantum critical point. Although significant progress has been made in understanding quantum critical behavior in some low dimensional magnetic insulators, the situation in metallic systems is much less clear. Here, we demonstrate that NiCoCrx single crystal alloys are remarkable model systems for investigating quantum critical point physics in a metallic environment. For NiCoCrx alloys with x ≈ 0.8, the critical exponents associated with a ferromagnetic quantum critical point are experimentally determined from low temperature magnetization and heat capacity measurements. All of the five exponents (γT ≈ 1/2, βT ≈ 1, δ ≈ 3/2, νzm ≈ 2, {bar {rm alpha}}T ≈ 0) are in remarkable agreement with predictions of Belitz–Kirkpatrick–Vojta theory in the asymptotic limit of high disorder. Using these critical exponents, excellent scaling of the magnetization data is demonstrated with no adjustable parameters. We also find a divergence of the magnetic Gruneisen parameter, consistent with a ferromagnetic quantum critical point. This work therefore demonstrates that entropy stabilized concentrated solid solutions represent a unique platform to study quantum critical behavior in a highly tunable class of materials.

Effect of excitation power on voltage induced local magnetization dynamics in an ultrathin CoFeB film

Voltage or electric field induced magnetization dynamics promises low power spintronics devices. For successful operation of some spintronics devices such as magnetic oscillators and magnetization switching devices a clear understanding of nonlinear magnetization dynamics is required. Here, we report a detailed experimental and micromagnetic simulation study about the effect of excitation power on voltage induced local magnetization dynamics in an ultrathin CoFeB film. Experimental results show that the resonance line-width and frequency remains constant, whereas cone angle of the magnetization precession increases linearly with square-root of excitation power below threshold value, known as linear excitation regime. Above threshold power, the dynamics enters into nonlinear regime where resonance line-width monotonically increases and resonance frequency monotonically decreases with increasing excitation power. Simulation results reveal that a strong nonlinear and incoherent magnetization dynamics are observed in our experiment above the threshold power which reduces dynamic magnetic signal by suppressing large cone angle of magnetization precession. Moreover, a significant transfer of spin angular momentum from uniform FMR mode to its degenerate spin waves outside of excitation area further restrict the cone angle of precession within only few degrees in our device. Our results will be very useful to develop all-voltage-controlled spintronics devices.

Lipid Droplets: Formation to Breakdown.

One of the most exciting areas of cell biology during the last decade has been the study of lipid droplets. Lipid droplets allow cells to store non-polar molecules such as neutral lipids in specific compartments where they are sequestered from the aqueous environment of the cell yet can be accessed through regulated mechanisms. These structures are highly conserved, appearing in organisms throughout the phylogenetic tree. Until somewhat recently, lipid droplets were widely regarded as inert, however progress in the field has continued to demonstrate their vast roles in a number of cellular processes in both mitotic and post-mitotic cells. No doubt the increase in the attention given to lipid droplet research is due to their central role in current pressing human diseases such as obesity, type-2 diabetes, and atherosclerosis. This review provides a mechanistic timeline from neutral lipid synthesis through lipid droplet formation and size augmentation to droplet breakdown.

Anticancer effect of artemisinin and its derivatives: Research progress, mechanism of action and future perspectives

There is an increasing interest in developing natural product anticancer agents that have better efficacy and safety profiles than conventional synthetic compounds. Artemisinin, which is clinically used antimalarial agent, has saved millions of lives across the global, especially in the developing world. Preclinical investigation and clinical experience have shown the potential anticancer effect of artemisinin and its derivatives. The major anticancer mechanisms of actions seem to be directed toward tumor cell growth and proliferation generated by cell cycle arrest and apoptosis mediated by reactive oxygen species (ROS) and inhibition of tumor angiogenesis. Multiple studies have shown additive synergistic effect of artemisinin on synthetic chemotherapeutic drugs such as doxorubicin, gemcitabine, paclitaxel, and cisplatin. This review provides a comprehensive discussion of these cellular responses and anti-tumor mechanism of artemisinin and its derivates, and potential combination with chemotherapies as well as some clinical trials involving artemisinins. However, the therapeutic potencies of artemisinin and some synthetic derivates such as dihydroartemisinin, artemether, arteether, and artesunate are limited by their low solubility, short half-life and poor bioavailability. Great efforts have been made to overcome these weaknesses via enhanced pharmacological and pharmacokinetics properties and targeted anticancer activities. Moreover, immunotherapy is one of the most exciting areas of new discoveries and treatments for many different kinds of cancer. Harnessing the synergy between immunotherapy and chemotherapy toward additive clinical activity can offer new direction to the use of artemisinins. More investigations are required on the immunomodulatory mechanisms of artemisinins in cancer. An effort is also made towards presentation the new directions on artemisinin studies such as the immunomodulation and immunotherapy and designation of novel artemisinin derivates with better biological activities. It is expected that this review will provide first-hand information on the anti-tumor development of artemisinin.

Promising biocidal activity of thymol loaded chitosan silver nanoparticles (T-C@AgNPs) as anti-infective agents against perilous pathogens

The advent of biodegradable polymer-encapsulated drug nanoparticles has made an exciting area of drug delivery research. The present study investigated novel and simple route for synthesis of thymol loaded chitosan silver nanoparticles (T-C@AgNPs) using chitosan and thymol as reducing, capping agent respectively to understand the therapeutic efficacy. The UV–vis spectroscopy, DLS, FT-IR, SEM, EDS, XRD used for characterization and radical scavenging activity, anti-microbial and biocompatibility was taken to ascertain an efficacy of novel T-C@AgNPs. The T-C@AgNPs intense peak at 490nm indicates the formation of nanoparticles and had average particle size of 28.94nm with spherical shape, monodisperse state in water, also exhibited excellent biocompatibility of cubic shaped pure silver element containing T-C@AgNPs. The antibacterial activity was studied for gram positive and gram negative food-borne pathogens and effective inhibition at 100μgmL−1 to S. aureus, S. epidermidis, S. haemolyticus (10.08, 10.00, 11.23mm) and S. typhimurium, P. aeruginosa and S. flexneri (9.28, 9.33, 12.03mm) compared to antibiotic Streptomycin. This study revealed the efficacy against multiple food-borne pathogens and therapeutic efficacy of T-C@AgNPs offers a valuable contribution in the area of nanotechnology. This proved to be a first-class novel antimicrobial material for the first time in this study.

A novel coordinated resource provisioning approach for cooperative cloud market

Cloud computing has been the enabling technology for shifting mass scale computation and storage requirements from individually owned clients towards an on-demand and utility styled alternative that provides many services. However, cost of maintaining datacenters, keeping the environmental ramifications of data centers at check, providing affordable computation alternative to users still needs to be addressed in a wholesome manner. One of the most exciting and recent research areas in cloud computing has been cloud federations that can mitigate the aforesaid problems. The past decade has seen immense efforts towards interoperability of clouds leading to realistic cloud federations. Motivated by these advancements and equipped with available technologies, this paper presents a detailed account of a cooperative cloud market. It delineates trading mechanisms of such cloud markets, extent of coordination among market players with illustrative examples. It also presents a novel two-phase coordinated resource reservation and provisioning (CRRP) approach that allocates cloud resources to users to meet the goal of minimizing users’ cost. To that end, this paper proposes a novel Most Cost Effective Providers’ Resources First (MCEPRF) algorithm. The efficiency of the proposed algorithm has been tested using synthetic data and the simulation results presented herein demonstrate the superiority of the proposed approach over its non-coordinated counterparts.

Graphene: A Comprehensive Review

Graphene, a one-atom thick, two-dimensional sheets of sp2hybridized carbon atoms packed in a hexagonal lattice with a Caron-Carbon distance of about 0.142 nm. Its extended honeycomb network forms the basic building block of other important allotropes; it can be stacked to form 3-Dgraphite, rolled to form 1-D-nanotubes and wrapped to form 0-D-fullerenes. Long-range π conjugation in graphene results in its extraordinary thermal, mechanical and electrical properties, which have been the interest of many theoretical studies and recently became an exciting area for scientists. Graphene is impermeable to gas and liquids, has excellent thermal conductivity and higher current density in comparison to other most effective materials. All of its exceptional properties have opened up new avenues for the use of graphene in nano-devices and nano-systems, which initiated its prominent use as a material for drug targeting. In addition, several fabrication techniques are outlined, starting from the mechanical exfoliation of high-quality graphene to the direct growth on silicon carbide or metal substrates and from the chemical routes utilizing graphene oxide to the newly developed approach at the molecular level. By this article reviewers intend to emphasize on unique properties, fabrication techniques and updated applications of graphene. In addition, we discuss about the potential of graphene in drug targeting in fields of nanotechnology, biomedical engineering and technology and its use for innovations in various fields such as electronics and photonics.

Computerised cardiotocography—study design hampers findings

Computerised cardiotocography—study design hampers findings

The cardiac electric field in psychrophilic and thermophilic fish during atrial depolarization

In psychrophilic and thermophilic fish, significant differences were revealed under an optimal body temperature in the heart rate, initial atrial activity duration and descending slope of the P II wave. Differences were also detected in atrial electric activity during the initial and final periods of depolarization, reflecting different localization of the initial excitation area and the movement of the depolarization front toward the atrioventricular border.

P293 Assessment of primary motor cortex plastic changes following the use of a new prosthetic system able to provide somatosensory feedback from the missing hand in an amputee patient: A TMS study

Introduction The cortical representation of a muscle can be significantly modified by plastic reorganization following a limb amputation. These plastic changes are not immutable and can be further modified restoring by the use of prosthesis like new bionic anthropomorphic prosthesis connected to the peripheral nervous system via bidirectional neural interfaces. Transcranial magnetic stimulation (TMS) is a non-invasive technique commonly used to assess topographical reorganization of motor brain areas. Objective The aim of this study is to evaluate the motor cortical reorganization of primary motor cortex with the TMS mapping technique in a left trans-radial amputee patient following the use of a novel prosthetic system able to provide somatosensory feed-back from the lost hand of the user. Materials and methods Cortical motor output was mapped via TMS (intensity 10% above standardized excitability motor Threshold) for each hemisphere at the beginning, after 1 month and 2 month of training with the new prosthetic system. Peripheral responses were recorded from forearm flexor and extensor carpi ulnaris muscles of both limbs. Resting and Active motor threshold were also collected during separate mapping of right and left hemispheres. Results No significant differences were found in the motor thresholds between the two hemispheres before and after implantation. Pre-surgical TMS motor maps showed a slight abnormal interhemispheric asymmetry of motor cortex topography, resulted in a smaller area of representation of muscles governing the stump compared to the area for the intact limb. Following training, post-surgical maps, showed a reduction and a partial reversal of this asymmetry because of an enlargement of the excitable area on the right hemisphere contralateral to the stump, leading towards a more symmetrical muscle representation in the two hemispheres, as in control subjects. Conclusions Our experiment provides a direct and unique evidence of brain plasticity changes occurring in the motor cortex following the use of a prosthetic system able to restore a somatosensory feedback from the missing limb after amputation. Figure options Download full-size image Download high-quality image (378 K) Download as PowerPoint slide Figure options Download full-size image Download high-quality image (399 K) Download as PowerPoint slide

Efficient Optical Amplification in a Sandwich-Type Active-Passive Polymer Waveguide Containing Perylenediimides

Polymer waveguides doped with luminescent materials serve as a suitable flexible platform for active elements (lasers and amplifiers) in on-chip optical circuits. However, at present, the best parameters (lowest thresholds) achieved with these devices are obtained with the use of the stripe excitation technique in the framework of which external illumination of an active material along the whole length of the waveguide is realized that is not convenient for the waveguide on-chip integration and requires high peak energies due to the large excitation area. In the present work, an elegant method is proposed to overcome this obstacle and provide efficient active material pumping along the whole waveguide length with use of on-chip integration compatible edge-type excitation light injection. This novel type of planar active-passive polymer waveguides includes a thin (50–100 nm) active layer of poly(methyl methacrylate) (PMMA), which is heavily doped with highly luminescent perylenediimide (PDI) molecules, san...

Potential Corticomotor Plasticity in Those with and without Chronic Ankle Instability.

Quantifying corticomotor alterations is important to understand the neurophysiological mechanisms that likely contribute to the neuromuscular control deficits observed in patients with chronic ankle instability (CAI). Corticomotor output mapping provides further insight into the changes within the motor cortex and identifies potential changes in the area of the motor cortex associated with selected muscles. Therefore, this investigation compared the corticomotor map output for the fibularis longus (FL) muscle in patients with and without CAI. Eighteen CAI patients and 16 healthy controls (HC) volunteered. Transcranial magnetic stimulation was used to map the motor cortex's representation of the FL. The normalized average of three motor evoked potentials at 100% of active motor threshold intensity was recorded for each scalp site on a 6 × 6 cm grid. Corticomotor output map was compared between groups through 1) the size of the corticomotor map area, 2) the volume of the corticomotor map, and 3) the location of cortical representation. Independent t-tests were used to assess group differences in each mapping outcome variable. Cohen's d effect sizes along with 95% confidence intervals were calculated using the pooled SD values. CAI patients exhibited less map volume (P = 0.018, CAI = 8.2 ± 3.2 cm mV vs HC = 11.3 ± 3.9 cm mV) and map area (P = 0.046, CAI = 12.8 ± 6.0 cm vs HC: 17.4 ± 6.9 cm) compared with HC. The smaller map area and volume suggest a more concentrated area of neurons communicating with the FL muscle in patients with CAI. Consequently, motor cortical cells on the border of the FL excitation area are less committed to the proper function of the FL muscle and may be recruited by other surrounding areas. This may explain altered movement strategies that lead to ankle reinjury.

Does U.S. Sub-Prime Crisis Impede Asian Equity Indices Integration Strengthens?: An Ardl-Bounds Testing Approach

Promotion of regional stock market integration is critically meaningful for regional development. Since last couple of decades stock markets Integration has been widely seen as the most exciting and promising area for investment, especially because they are expected to generate high returns and to offer good portfolio diversification opportunities. Consequently, these markets have known a considerable expansion. For this motive, we examine the integration of principal Asian equity markets namely; Taiwan, Sri Lanka, Korea, China, Japan, Malaysia, Hong Kong, India, Singapore and Pakistan employing ARDL bounds testing approach to co-integration and VECM. The study employed monthly stock indices data covering from July 1997 to June 2015. For this purpose list of following indices are used to represent the markets: TSEC weighted index for Taiwan, CSE for Sri Lanka, KOSPI composite index for Korea, SSE composite index for China, Nikkei 225 index for Japan, FTSE 100 index for Malaysia, Hang Seng index for Hong Kong, BSE Sensex for India, Strait Time Index for Singapore and KSE 100 index for Pakistan. We investigate null hypothesis (H0) of no long run relationship as well the direction of causality in case of rejection of (H0). Study explore the Asian markets are integrated during sample period of pre- and post-2008 U.S sub-prime crisis which is in line with prior literature, to extent, this study further explore more attractive results of integration among sample indices and concludes that adjustment of (ECT-1) improved expressively in post-crisis period compare to pre-crisis period over sample years. This implies that the strength of long-run relationship among Asian markets increase over the post-crisis period. The overall comparison results of sample Asian stock indices pre- and post U.S sub-prime crisis conclude that, the integration of sample indices are more strengthen in Asian markets after the global financial crisis. It would be interesting to further explore the factors leading for market integration like, trade flow of the countries, foreign institutional/private portfolio investments, previous equity returns and more precisely put on structural breaks to measure the strength of US crisis period. In addition, it would be more strengthen to make sound policy coordination among Asian region to overcome the influence of economic instabilities and financial fluctuations.

How Shear Wave is Generated by Acoustic Radiation Force and Propagates in Kidney

We have experienced frequent failure of shear wave elastography (SWE) on kidney. In our past investigation, the shear wave (SW) arrival was unclear, or could not be distinguished from the background fluctuation in the displacement profile. In this study, we investigated the physical mechanism of this phenomenon in detail. Here we made three hypotheses: (1) Generated SW is obscured because of blood flow, (2) Push-pulse cannot generate SW in kidney, (3) Complicated structure with dense and fine renal vessels interferes with the propagation of SW. We analyzed received IQ data of SWE for three excised swine kidneys, a natural sponge (to mimic porous structure of the kidney), and two healthy volunteers (liver and kidney). The swine kidneys and the sponge were scanned in water. The ultrasound scanner used was LOGIQ E9 (GE Healthcare) with a 3.5 MHz convex probe (C1-6-D). For the volunteer scan, acoustic intensity of the push-pulse was varied between three levels: same level as clinical recommendation, a half of it, and zero (no push). When scanning livers, we included a large portal vein intentionally for comparison. Acquired IQ data (echo signals of a series of tracking pulses) were transferred into a PC and analyzed into the velocity distribution and its change over time after push-pulse insonification. Those changes of velocity distribution were visually inspected, while average velocity and standard deviation were calculated over time inside the area of push-pulse insonification. For the swine kidney, SWE images were sufficiently homogeneous. IQ data analysis revealed an evident propagation of SW. For the volunteer, typical velocity peak was observed in liver and kidney. Amplitudes of SW were sufficient compared to the background fluctuation by blood flow, and this fluctuation was larger in kidney than in liver. At the same time, however, kidney contained many pixels which indicate irregular velocity profiles. In those pixels, background velocity fluctuation was large, and therefore a typical pattern of shear wave arrival was not recognized. Such signals were also observed in a large portal vein. In addition, the shape of generated SW was different between the two organs, especially in one of the two volunteers. The region of excitation (area of deformation induced by push-pulse) was wide and not smooth in kidney. The sponge also presented such a rough velocity distribution, while the average velocity induced by the push-pulse was comparable with that for livers and kidneys. The background fluctuation in velocity profile decreased with higher push-pulse intensity level in both liver and kidney. This implies that the shear wave has an effect of pushing blood flow out from its traveling area. From all the above results, we concluded that all the three hypotheses were reasonable. As for the second hypothesis, based on the sponge experiment results, it is suggested that it is rather inhomogeneous and porous structure than vascularity that affects the appearance of generated shear wave. Considering the result of swine kidney, however, the vascularity is thought to contribute to the characteristic structure of kidney. The question remains why the clear SW generation was observed in one volunteer’s kidney (and why not in the other’s). The difference in speed and pressure of the blood flow might be one of the possible factors.

Abiotic Fluorescent Receptors for Detection of Pb2+ in Aqueous Media as well as Living Cells: Mechanistic and Sensing Aspects

Substantial utility of lead in numerous industries (storage, batteries, gasoline, cable manufacture, paint and ammunition), has resulted in recurring of environmental contamination. Lead being one of the highly abundant elements in nature, ranks third among the list of toxic substances. Owing to its ever-increasing demand and allied toxicity (memory loss, irritability, anemia, muscle paralysis, and mental retardation), development of novel synthetic receptors suitable to track Pb2+ in vitro as well as in vivo has been an exciting area of research in the past few decades. In this review, emphasis has been diverted to summarize and briefly discuss major contributions made towards development of fluorescent abiotic receptors capable of sensing ionic lead (Pb2+) under aqueous environments as well as in living cells.

Antimicrobial activities screening of some phytochemicals from the stem bark extracts of Bersama abyssinica (Fresen)

Currently, drug resistance among bacterial species is a serious problem in public health thus the discovery and development of new antimicrobial drugs from plants sources would be one of the most exciting areas of pharmacological research. The present study extends the efforts of discovering drug templates from a local medicinal Kenyan plant. The work investigated the phytochemistry and antibacterial activities of stem bark extract of Bersama abyssinica by disc diffusion method. The stem bark of B. abyssinica was extracted at an increasing gradient of organic solvents (n- hexane, dichlomethane, ethyl acetate and methanol). Phytochemistry analysis results confirmed the presence of four main compounds sitosterol, sitosterol glucoside, stigmasterol, and lupeol. Evaluation of antibacterial activities of crude stem bark extracts and the isolated compounds of B. abyssinica carried out through disc diffusion method against Escherichia coli, Staphylococcus aureus, Klebsiella pneumonia, Bacillus subtilis, Vibrio cholerae and Pseudomonas aeruginosa. B. abyssinica methanol stem bark extract exhibited much higher antibacterial activity against the tested pathogenic bacteria. The dichloromethane extract showed mild and moderate antibacterial activity. Results proved that B.abyssinica stem bark possessed antipotential bacterial activity. It was concluded that B. abyssinica contains secondary metabolites with antibacterial activity against both Gram positive and Gram negative bacteria. The result of antibacterial activities the plant extracts justifies its continued use in Ethnomedicine.

High Sensitivity Hepcidin-25 Bioactive Elisas: Manual and Fully Automated System for the Quantification of Hepcidin-25 in Human Serum and Plasma

▪Since its discovery as the master regulator of iron homeostasis, hepcidin has been an exciting area of research with far reaching clinical and therapeutic applications. The bioactive peptide Hepcidin-25 is generated predominantly in the liver by proteolytic cleavage of the C-terminal 25 amino acids of prohepcidin. Subsequent N-terminal processing of Hepcidin-25 results in smaller peptides of 20-24 amino acids that show greatly reduced activity and accumulate in the urine. Hepcidin regulates iron levels by down regulating ferroportin, the major cellular iron exporter in the membrane of macrophages, hepatocytes, and the basolateral site of enterocytes. Hepcidin-25 induces the internalization and degradation of ferroportin, resulting in increased intracellular iron stores, decreased dietary iron absorption, and decreased circulating iron concentrations. Hepatocellular hepcidin synthesis decreases under conditions of increased demand for circulating iron like iron deficiency, hypoxia, anemia, and erythropoiesis. In contrast, hepcidin synthesis is induced by inflammation and infection. Measuring serum levels of Hepcidin-25 has proven to be valuable in identifying and differentiating specific disease conditions. Hepcidin deficiency causes hereditary hemochromatosis, characterized by body iron overload that may progress to liver cirrhosis. In addition, low Hepcidin-25 concentration can be induced by iron loading anemias and chronic hepatitis C. In contrast, high Hepcidin-25 levels have been found in iron-refractory iron-deficiency anemia, during infection, chronic kidney disease. There have reported links of hepcidin dysregulation in cancer and other disease states. This exciting area of biology has many potential important applications.To further advance the field of hepcidin research and clinical application two new assays have been developed, the manual high sensitive DRG Hepcidin-25 assay and the fully automated Hepcidin 25 (bioactive) which is available on the DRG Hybrid XL. Both assays are colorimetric solid phase enzyme-linked immunosorbent assays (ELISA) based on the competitive binding of hepcidin in the sample and biotinylated hepcidin to immobilized anti-hepcidin antibody, followed by the detection with a Streptavidin-HRP conjugate.The DRG Hepcidin-25 assay allows the quantitative determination of Hepcidin-25 covering a measuring range form 0.15-81.0 ng/mL and the total assay time for the manual assay is 1.5 hours. Serum and plasma (EDTA, heparin, Citrate) can be used for both the manual and automated assays. The analytical sensitivity of the assay is 0.153 ng/ml. The test shows good reproducibility with an intra-assay precision of 6.97% and an inter-assay precision of 12.0%. The recovery was determined to be 97.3%. Linear dilution gave an excellent overall recovery of 97.9% (mean of 3 samples, each diluted 4-fold with dilution buffer; range from 89.1-105.2%). We found no matrix interference with haemoglobin and triglycerides (up to 7.5 mg/mL). Inter-Lot precision was 7.69% (mean of 3 samples measured with 3 lots in 6 determinations). The assay also shows a good correlation to mass spectrometry (y=1.013x +1.3865, r=0.9678). Benefits of the new assay are a very straight forward procedure with ready-to-use reagents, no shaking, high sensitivity, and a short total assay time of 1.5 hours.In addition to the highly acclaimed manual assay a new fully automated Hepcidin assay has been developed for the DRG Hybrid XL. The fully automated Hepcidin 25 assay time is 2 hours. The dynamic range is 1.67 ng/mL - 81 ng/ml. Intra assay precision is 2.6% and inter assay precision is 13.7%. Recovery averages 100.6% and linearity 100.1%. Both assays are excellent tools for detecting bioactive Hepcdin-25 in human samples and advancing this exciting field of research. DisclosuresNo relevant conflicts of interest to declare.

Network analysis and modelling: Special issue ofEuropean Journal of Applied Mathematics

This special issue of theEuropean Journal of Applied Mathematicsfeatures research articles onnetworks, one of the most exciting areas of applied mathematics.

A Novel Algorithm to Derive Spread of Excitation Based on Deconvolution.

The width of the spread of excitation (SOE) curve has been widely thought to represent an estimate of SOE. Therefore, correlates between psychophysical parameters, such as pitch discrimination and speech perception, and the width of SOE curves, have long been investigated. However, to date, no relationships between these objective and subjective measurements have yet been determined. In a departure from the current thinking, the authors now propose that the SOE curve, recorded with forward masking, is the equivalent of a convolution operation. As such, deconvolution would be expected to retrieve the excitation areas attributable to either masker or probe, potentially more closely revealing the actual neural SOE. This study aimed to develop a new analytical tool with which to derive SOE using this principle. Intraoperative SOE curve measurements of 16 subjects, implanted with an Advanced Bionics implant, were analyzed. Evoked compound action potential (ECAP)-based SOE curves were recorded on electrodes 3 to 16, using the forward masker paradigm, with variable masker. The measured SOE curves were then compared with predicted SOE curves, built by the convolution of basic excitation density profiles (EDPs). Predicted SOE curves were fitted to the measured SOEs by iterative adjustment of the EDPs for the masker and the probe. It was possible to generate a good fit between the predicted and measured SOE curves, inclusive of their asymmetry. The rectangular EDP was of least value in terms of its ability to generate a good fit; smoother SOE curves were modeled using the exponential or Gaussian EDPs. In most subjects, the EDP width (i.e., the size of the excitation area) gradually changed from wide at the apex of the electrode array, to narrow at the base. A comparison of EDP widths to SOE curve widths, as calculated in the literature, revealed that the EDPs now provide a measure of the SOE that is qualitatively distinct from that provided using conventional methods. This study shows that an eCAP-based SOE curve, measured with forward masking, can be treated as a convolution of EDPs for masker and probe. The poor fit achieved for the measured and modeled data using the rectangular EDP, emphasizes the requirement for a sloping excitation area to mimic actual SOE recordings. Our deconvolution method provides an explanation for the frequently observed asymmetry of SOE curves measured along the electrode array, as this is a consequence of a wider excitation area in the apical part of the cochlea, in the absence of any asymmetry in the actual EDP. In addition, broader apical EDPs underlie the higher eCAP amplitudes found for apical stimulation.