Optimal Portfolio Rule: When There is Uncertainty in The Parameter Estimates

The classical mean-variance model, proposed by Harry Markowitz in 1952, has been one of the most powerful tools in the field of portfolio optimization. In this model, parameters are estimated by their sample counterparts. However, this leads to estimation risk, which the model completely ignores. In addition, the mean-variance model fails to incorporate behavioral aspects of investment decisions. To remedy the problem, the notion of ambiguity aversion has been addressed by several papers where investors acknowledge uncertainty in the estimation of mean returns. We extend the idea to the variances and correlation coefficient of the portfolio, and study their impact. The performance of the portfolio is measured in terms of its Sharpe ratio. We consider different cases where one parameter is assumed to be perfectly estimated by the sample counterpart whereas the other parameters introduce ambiguity, and vice versa, and investigate which parameter has what impact on the performance of the portfolio

Editorial Nanomaterials for Optical Sensing and Sensors: Plasmonics, Raman, and Optofluidics

To date, environmental and healthcare problems have become the most important and challenging issues globally. Demands for fast and low-cost sensing methods and devices for environment monitoring This special issue contains 6 articles which cover the academic fields of environmental science, materials science, life science, nanotechnology, optics, physics, and chemistry. In the research article "Investigation of the Validity of the Universal Scaling Law on Linear Chains of Silver Nanoparticles," M. Alsawafta et al. examined (the generalization of) the universal scaling behavior for spherical silver nanoparticles arranged in finite linear chains (eight nanoparticles) and embedded in different host media. The results of simulation show that the plasmon ruler equation can be successfully extended to represent the fractional plasmon shift of many interacting nanoparticles. The decay length and the mount of the fractional shift of the silver linear chains strongly depend on the polarization state of the incident polarization. The LM exhibits a significant shift of the plasmon resonance (indicated by the value of ) as compared to that of the TM. This can be explained by the fact that the enhancement of the local field under parallel polarization is more pronounced. On the other hand, the decay of the TM shows a strong dependency on the dielectric function of the surrounding medium. It decays twice faster than the LM, as the host medium becomes denser. In the research article "Focused Ion Beam Assisted Interface Detection for Fabricating Functional Plasmonic Nanostructures," H. Wang et al. proposed the FIB-assisted interface detection and successfully carried out it using the sampleabsorbed current as the detection signal, and the patterning depth control for the plasmonic structure fabrication was achieved through controlling machining time or ion dose using the EPM. Material-dependent currents were measured through the EPM signal curves, and the quantitative models for the sample-absorbed currents and the ion beam current were also developed. In the research article "Immobilization Techniques and Integrated Signal Enhancement for POC Nanocolor Microfluidic Devices," M. Schlauf et al. reported the development of a silver enhancement technology that operates even in the presence of high chloride concentrations as it may be encountered in biologic samples. The silver enhancement reagents may be integrated into the microfluidic assay platform to be released upon sample addition. Hereby a highly sensitive onestep-assay can be realized. M. Schlauf et al. also demonstrated that adsorptive immobilization via a cationic polymeric interlayer is a competitive and fast technique for the binding of the capture protein streptavidin onto planar SiO 2 -surfaces such as REA biochips. In the research article "Investigating the Fabrication Imperfections of Plasmonic Nanohole Arrays and its Effect on the Optical Transmission Spectra," A. M. Mahros et al. investigated the extraordinary optical transmission spectra of thin gold films perforated with imperfect nano hole arrays using the finite difference time domain (FDTD) method. Exponential shapes for the nanohole sidewalls are used. The investigation of transmission spectra of imperfect nanohole arrays has not previously been demonstrated. It was found that the asymmetry between the two openings of the circular nanoholes or bending to their sidewalls strongly modifies both of the intensity and resonance positions of the transmission spectra. Furthermore, the results of this study assist in explaining the technicality of extraordinary optical transmission phenomenon and why some experimental results on transmission differ from those expected. In the research article "FRET-Based Detection of Enzymatic Reaction of Botulinum on Microfluidic Device," Y. M. Bae et al. implemented a microfluidic device to detect the enzymatic reaction of botulinum toxin A (BTA) using Förster resonance energy transfer (FRET). The microfluidic device comprised a main channel having two loading zones, a reaction chamber, and a side channel perpendicular to the main channel. The reaction chamber defined by weir in the main channel was packed with microbeads. The movement of the peptide substrate and the BTA in the microfluidic device was controlled by electrophoresis, and the enzymatic reaction of the BTA was detected through the changes of the fluorescence intensity in the reaction chamber. As a result, it was observed that the enzymatic reaction was affected by the electric voltage applied for the movement of the BTA and the peptide and improved by packing the microbeads in the reaction chamber. The microfluidic device provides with the tool to investigate the proteolysis of the substrate by the BTA. In the research article "Molecular Logic Computation with Debugging Method," X. Liu et al. considered constructing full adder and serial binary adder, using the new concept of seesaw gate. The simulation of the full add preformed properly as designed; however, unexpected exception is noted in the simulation of the serial binary adder. To identify and address the exception, they propose a new method for debugging the molecular circuit. The main idea for this method is to add fan-outs to monitor the circuit in a reverse stepwise manner. These fan-outs are fluorescent signals that can obtain the real-time concentration of the target molecule. By analyzing the monitoring result, the exception can be identified and located. In this paper, examples of XOR and serial binary adder circuits are described to prove the practicability and validity of the molecular circuit debugging method

The mid-infrared view of red sequence galaxies in Abell 2218 with <i>AKARI</i>

We present the AKARI Infrared Camera (IRC) imaging observation of early-type galaxies (ETGs) in A2218 at z ~ 0.175. Mid-infrared (MIR) emission from ETGs traces circumstellar dust emission from asymptotic giant branch (AGB) stars or/and residual star formation. Including the unique imaging capability at 11 and 15 μm, our AKARI data provide an effective way to investigate MIR properties of ETGs in the cluster environment. Among our flux-limited sample of 22 red sequence ETGs with precise dynamical and line strength measurements (less than 18 mag at 3 μm), we find that at least 41% have MIR-excess emission. The N3 – S11 versus N3 (3 and 11 μm) color-magnitude relation shows the expected blue sequence, but the MIR-excess galaxies add a red wing to the relation especially at the fainter end. A spectral energy distribution analysis reveals that the dust emission from AGB stars is the most likely cause of the MIR excess, with a low level of star formation being the next possible explanation. The MIR-excess galaxies show a wide spread of N3 – S11 colors, implying a significant spread (2-11 Gyr) in the estimated mean ages of stellar populations. We study the environmental dependence of MIR-excess ETGs over an area out to a half virial radius (~1 Mpc). We find that the MIR-excess ETGs are preferentially located in the outer region. From this evidence, we suggest that the fainter, MIR-excess ETGs have just joined the red sequence, possibly due to the infall and subsequent morphological/spectral transformation induced by the cluster environment

A pan-cancer analysis of the clinical and genetic portraits of somatostatin receptor expressing tumor as a potential target of peptide receptor imaging and therapy

Abstract Purpose Although somatostatin receptor (SST) is a promising theranostic target and is widely expressed in tumors of various organs, the indication for therapies targeting SST is limited to typical gastroenteropancreatic neuroendocrine tumors (NETs). Thus, broadening the scope of the current clinical application of peptide receptor radiotherapy (PRRT) can be supported by a better understanding of the landscape of SST-expressing tumors. Methods SST expression levels were assessed in data from The Cancer Genome Atlas across 10,701 subjects representing 32 cancer types. As the major target of PRRT is SST subtype 2 (SST2), correlation analyses between the pan-cancer profiles, including clinical and genetic features, and SST2 level were conducted. The median SST2 expression level of pheochromocytoma and paraganglioma (PCPG) samples was used as the threshold to define high-SST2 tumors. The prognostic value of SST2 in each cancer subtype was evaluated by using Cox proportional regression analysis. Results We constructed a resource of SST expression patterns associated with clinicopathologic features and genomic alterations. It provides an interactive tool to analyze SST expression patterns in various cancer types. As a result, eight of the 31 cancer subtypes other than PCPG had more than 5% of tumors with high-SST2 expression. Low-grade glioma (LGG) showed the highest proportion of high-SST2 tumors, followed by breast invasive carcinoma (BRCA). LGG showed different SST2 levels according to tumor grade and histology. IDH1 mutation was significantly associated with high-SST2 status. In BRCA, the SST2 level was different according to the hormone receptor status. High-SST2 status was significantly associated with good prognosis in LGG patients. High-SST2 status showed a trend for association with poor prognosis in triple-negative breast cancer subjects. Conclusion A broad range of SST2 expression was observed across diverse cancer subtypes. The SST2 expression level showed a significant association with genomic and clinical aspects across cancers, especially in LGG and BRCA. These findings extend our knowledge base to diversify the indications for PRRT as well as SST imaging

Characteristics of mid-infrared PAH emission from star-forming galaxies selected at 250 μm in the North Ecliptic Pole field

Evolutionary properties of infrared (IR) luminous galaxies are important keys to understand dust-obscured star formation history and galaxy evolution. Based on near- to mid-IR imaging with nine continuous filters of the AKARI space telescope, we present the characteristics of dusty star-forming (SF) galaxies showing polycyclic aromatic hydrocarbon (PAH) features observed by the North Ecliptic Pole (NEP) wide field survey of AKARI and Herschel. All the sample galaxies from the AKARI/NEP-Wide data are selected based both on the Herschel/SPIRE 250 μm detection and optical spectroscopic redshift data. The physical modeling of spectral energy distribution (SED) using all available data points from u* to sub-mm 500 μm band, including WISE and PACS data where available, takes unique advantages of the continuous near- to mid-IR coverage, the reliable constraint on the far-IR peak, and spectroscopically determined accurate redshifts, as well as the energy balance principle by MAGPHYS. This enables us to derive physically meaningful and accurate total infrared luminosity and 8 μm (or PAH) luminosity consistently. Our sample galaxies are in the redshift range z < 1, and the majority of them appear to be normal SF/spiral populations showing PAH features near 8 μm. These SF galaxies showing PAHs in the mid-IR include various types, from quiescent to starbursts. Some of our sample show shortage of 8 μm luminosity compared to the total IR luminosity and this PAH deficit gets severe in more-luminous IR galaxies, suggesting PAH molecules in these galaxies are destroyed by a strong radiation field from the SF region or a large amount of cold dust in the interstellar medium. The specific SFR of our sample shows mass-dependent time evolution which is consistent with a downsizing evolutionary pattern

Merging Galaxy Cluster A2255 in Mid-infrared

We present the mid-infrared (MIR) observation of a nearby galaxy cluster, A2255, by the AKARI space telescope. Using AKARI's continuous wavelength coverage between 3 and 24 μm and the wide field of view, we investigate the properties of cluster member galaxies to see how the infall of the galaxies, the cluster substructures, and the cluster-cluster merger influence their evolution. We show that the excess of MIR (~11 μm) flux is a good indicator for discriminating galaxies at different evolutionary stages and for dividing galaxies into three classes accordingly: strong MIR-excess (N3 – S11 > 0.2) galaxies that include both unobscured and obscured star-forming galaxies; weak MIR-excess (–2.0 5 Gyr) galaxies where the MIR emission arises mainly from the circumstellar dust around AGB stars; and intermediate MIR-excess (–1.2 < N3 – S11 < 0.2) galaxies in between the two classes that are less than a few Gyr old past the prime star formation activity. With the MIR-excess diagnostics, we investigate how local and cluster-scale environments affect the individual galaxies. We derive the total star formation rate (SFR) and the specific SFR of A2255 using the strong MIR-excess galaxies. The dust-free, total SFR of A2255 is ~130 M_⊙ yr^(–1), which is consistent with the SFRs of other clusters of galaxies at similar redshifts and with similar masses. We find no strong evidence that supports enhanced star formation either inside the cluster or in the substructure region, suggesting that the infall or the cluster merging activities tend to suppress star formation. The intermediate MIR-excess galaxies, representing galaxies in transition from star-forming galaxies to quiescent galaxies, are located preferentially at the medium density region or cluster substructures with higher surface density of galaxies. Our findings suggest that galaxies are being transformed from star-forming galaxies into red, quiescent galaxies from the infall region through near the core which can be explained well by ram-pressure stripping as previous simulation results suggest. We conclude that the cluster merging and the group/galaxy infall suppress star formation and transform galaxies from star-forming galaxies into quiescent galaxies, most likely due to ram-pressure stripping

NEPSC2, the North Ecliptic Pole SCUBA-2 survey: 850-<i>μ</i>m map and catalogue of 850-<i>μ</i>m selected sources over 2 deg²

Abstract We present an 850-μm mosaic map and extracted catalogue of submillimetre sources in the extended North Ecliptic Pole (NEP) region over about 2 deg2. The 850-μm map is constructed using newly obtained observations by SCUBA-2 at the East Asian Observatory’s James Clerk Maxwell Telescope, carried out using the observatory’s large programme opportunities. The recent 850-μm survey has extended the submillimetre data coverage by almost a factor of 4 compared to previous surveys, with a depth of σrms = 1.0–2.3 mJy beam−1. The catalogue contains 549 sources selected above a significance level of 4σ, where the false-detection rate is 10 per cent; a higher threshold of 4.5σ is required in order to achieve a false-detection rate below 3 per cent, which results in 342 sources being selected. Despite the large spatial variation of the noise, the deboosted flux density of sources is comparable to results from the SCUBA-2 Cosmology Legacy Survey (S2CLS), which covered the central 0.6 deg2 of our survey area with better sensitivity. We construct the source counts at 850 μm, finding results in agreement with other 850-μm surveys in cosmological blank fields over S850 = 4–15 mJy. We find a slight excess of bright galaxies (S850 > 15 mJy), which can be considered to be at ɀphot = 2–4. The 850-μm data adds valuable long-wavelength information to mid-infrared-selected sources from the AKARI NEP-deep and NEP-wide surveys, which will be helpful in preparing for future near-infrared to millimetre wavelength observations in the NEP region. Our 850-μm mosaic map and source catalogue will be made publicly available

Carbon nanotube strain sensors with wide dynamic range fabricated on flexible substrates by novel processing techniques

Carbon nanotube (CNT) strain sensors on flexible polyimide substrates with novel fabrication techniques have been fabricated. Excimer laser photoablation was used for simultaneous patterning of the CNT layer and the polyimide substrate. A transferring technique utilizing sacrificial etching was used for clear material transfer. Clear patterns free of CNT-polymer composites were made and were successfully transferred to a flexible substrate. The resulting device has a gauge factor of 60, which is comparable to the 50~150 value for silicon strain sensors. The device exhibits a dynamic range of up to 1.5% strain, far superior to the 0.03% of silicon

Subwavelength nanostructures for optical biosensing and rapid photochemical reactions

This thesis reports on the experimental examination of the use of nanostructures for three topics of light-matter interaction. First, enhanced photon absorption for photocatalytic reactions has been demonstrated. Photocatalytic metal nanoparticle synthesis is of significant interest in plasmonic biosening due to the simple fabrication capability. However, long synthesis time of more than 10 hours and the use of particle stabilization chemical agents hinder economical and rapid synthesis of such metal nanoparticle systems. We demonstrate a Si subwavelength nanostructure-based photochemical device. We show rapid photocatalytic structure transformation of noble metal nanoparticle ionization and reduction within 5 minutes with only pure water and room light illumination. Second, 3D nanostructures for optical biosensing have been investigated. We demonstrate optical spectroscopy by using subwavelength dielectric nanostructures as the substrate material for localized surface plasmon resonance metallic nanoparticles. Nanostructured substrates made of Si and Si3N4 have been characterized and compared. Schemes of enhancing the optical signal extraction are also discussed. We show the potential of dielectric based nanostructure substrate for applications in optical molecular sensing. Third, the experimental approaches from the two demonstrations are merged for photocatalytic nanoparticles. TiO2 nanoparticles are formed along the sidewall of subwavelength Si nanostructure. The dual semiconductor system is investigated for photocatalytic bacteria disinfection in water. We show disinfection of E. coli with just room light illumination on our proposed device. Possibilities of extending this device towards water splitting are also discussed. Each application is introduced with a brief motivation, description of the experimental method, and discussion of the results. Possible future directions are also presented

Antimicrobial Characterization of Erythorbyl Laurate for Practical Applications in Food and Cosmetics

In this study, antimicrobial spectrum of erythorbyl laurate (EL) against bacteria and fungi, leading to food-borne and infectious skin diseases, was evaluated for its practical applications in food and cosmetics. Furthermore, the influences of environmental factors including pH, oxidative stress, and dispersion medium on antimicrobial activity of EL were investigated. The three Gram-positive bacteria and the three molds were susceptible to 3.0 mM EL, while the yeast was susceptible to 6.0 mM EL. It was demonstrated EL retained antibacterial activity against Staphylococcus aureus after being oxidized while the antibacterial activity against the three Gram-positive bacteria including S. aureus, Bacillus cereus, and Listeria monocytogenes was significantly enhanced as decrease of pH from 7.0 to 5.0. Moreover, EL exhibited bactericidal effects against both Gram-positive and Gram-negative bacteria in an oil-in-water emulsion. Treatment of 5.0 mM EL for 4 h reduced 5.29 ± 0.24, 6.01 ± 0.18, 5.95 ± 0.13, and 6.24 ± 0.30 log CFU/mL against S. aureus, L. monocytogenes, Pseudomonas aeruginosa, and Escherichia coli, respectively. In a multipassage resistance selection study, it was observed minimum inhibitory concentrations of EL against S. aureus were not increased over 20 passages, indicating EL might not develop drug resistance of bacteria. This study suggests EL has a potential to be applied as the multifunctional additive in food and cosmetics