Halide Perovskites and Their Derivatives for Efficient, High-Resolution Direct Radiation Detection: Design Strategies and Applications

The past decade has witnessed a rapid rise in the performance of optoelectronic devices based on lead-halide perovskites (LHPs). The large mobility-lifetime products and defect tolerance of these materials, essential for optoelectronics, also make them well-suited for radiation detectors, especially given the heavy elements present, which is essential for strong X-ray and γ-ray attenuation. Over the past decade, LHP thick films, wafers, and single crystals have given rise to direct radiation detectors that have outperformed incumbent technologies in terms of sensitivity (reported values up to 3.5 × 106 µC Gyair -1 cm-2 ), limit of detection (directly measured values down to 1.5 nGyair s-1 ), along with competitive energy and imaging resolution at room temperature. At the same time, lead-free perovskite-inspired materials (e.g., methylammonium bismuth iodide), which have underperformed in solar cells, have recently matched and, in some areas (e.g., in polarization stability), surpassed the performance of LHP detectors. These advances open up opportunities to achieve devices for safer medical imaging, as well as more effective non-invasive analysis for security, nuclear safety, or product inspection applications. Herein, the principles behind the rapid rises in performance of LHP and perovskite-inspired material detectors, and how their properties and performance link with critical applications in non-invasive diagnostics are discussed. The key strategies to engineer the performance of these materials, and the important challenges to overcome to commercialize these new technologies are also discussed.

Polarimetric imaging combining optical parameters for classification of mice non-melanoma skin cancer tissue using machine learning

Polarimetric imaging systems combining machine learning is emerging as a promising tool for the support of diagnosis and intervention decision-making processes in cancer detection/staging. A present study proposes a novel method based on Mueller matrix imaging combining optical parameters and machine learning models for classifying the progression of skin cancer based on the identification of three different types of mice skin tissues: healthy, papilloma, and squamous cell carcinoma. Three different machine learning algorithms (K-Nearest Neighbors, Decision Tree, and Support Vector Machine (SVM)) are used to construct a classification model using a dataset consisting of Mueller matrix images and optical properties extracted from the tissue samples. The experimental results show that the SVM model is robust to discriminate among three classes in the training stage and achieves an accuracy of 94 % on the testing dataset. Overall, it is provided that polarimetric imaging systems and machine learning algorithms can dynamically combine for the reliable diagnosis of skin cancer.

Machine learning approaches for predicting Cracking Tolerance Index (CTIndex) of asphalt concrete containing reclaimed asphalt pavement

One of the various sorts of damage to asphalt concrete is cracking. Repeated loads, the deterioration or aging of material combinations, or structural factors can contribute to the development of cracks. Asphalt concrete's crack resistance is represented by the CT index. 107 CT Index data samples from the University of Transport Technology's lab are measured. These data samples are used to establish a database from which a Machine Learning (ML) model for predicting the CT Index of asphalt concrete can be built. For creating the highest performing machine learning model, three well-known machine learning methods are introduced: Random Forest (RF), K-Nearest Neighbors (KNN), and Multivariable Adaptive Regression Spines (MARS). Monte Carlo simulation is used to verify the accuracy of the ML model, which includes the Root Mean Square Error (RMSE), Mean Absolute Error (MAE), Mean Absolute Percentage Error (MAPE), and coefficient of determination (R2). The RF model is the most effective ML model, according to analysis and evaluation of performance indicators. By SHAPley Additive exPlanations based on RF model, the input Aggregate content passing 4.75 mm sieve (AP4.75) has a significant effect on the variation of CT Index value. In following, the descending order is Reclaimed Asphalt Pavement content (RAP) > Bitumen content (BC) > Flash point (FP) > Softening point > Rejuvenator content (RC) > Aggregate content passing 0.075mm sieve (AP0.075) > Penetration at 25°C (P). The results study contributes to selecting a suitable AI approach to quickly and accurately determine the CT Index of asphalt concrete mixtures.

Rapid and Direct Liquid-Phase Synthesis of Luminescent Metal Halide Superlattices

The crystallization of nanocrystal building blocks into artificial superlattices has emerged as an efficient approach for tailoring the nanoscale properties and functionalities of novel devices. To date, ordered arrays of colloidal metal halide nanocrystals have mainly been achieved by using post-synthetic strategies. Here, a rapid and direct liquid-phase synthesis is presented to achieve a highly robust crystallization of luminescent metal halide nanocrystals into perfect face-centered-cubic (FCC) superlattices on the micrometer scale. The continuous growth of individual nanocrystals is observed within the superlattice, followed by the disassembly of the superlattices into individually dispersed nanocrystals owing to the highly repulsive interparticle interactions induced by large nanocrystals. Transmission electron microscopy characterization reveals that owing to an increase in solvent entropy, the structure of the superlattices transforms from FCC to hexagonal close-packed (HCP) and the nanocrystals disassemble. The FCC superlattice exhibits a single and slightly redshifted emission, due to the reabsorption-free property of the building block units. Compared to individual nanocrystals, the superlattices have three times higher quantum yield with improved environmental stability, making them ideal for use as ultrabright blue-light emitters. This study is expected to facilitate the creation of metamaterials with ordered nanocrystal structures and their practical applications.

Combined Mueller matrix imaging and artificial intelligence classification framework for Hepatitis B detection

SIGNIFICANCE

The combination of polarized imaging with artificial intelligence (AI) technology has provided a powerful tool for performing an objective and precise diagnosis in medicine.

AIM

An approach is proposed for the detection of hepatitis B (HB) virus using a combined Mueller matrix imaging technique and deep learning method.

APPROACH

In the proposed approach, Mueller matrix imaging polarimetry is applied to obtain 4 × 4 Mueller matrix images of 138 HBsAg-containing (positive) serum samples and 136 HBsAg-free (negative) serum samples. The kernel estimation density results show that, of the 16 Mueller matrix elements, elements M 22 and M 33 provide the best discriminatory power between the positive and negative samples.

RESULTS

As a result, M 22 and M 33 are taken as the inputs to five different deep learning models: Xception, VGG16, VGG19, ResNet 50, and ResNet150. It is shown that the optimal classification accuracy (94.5%) is obtained using the VGG19 model with element M 22 as the input.

CONCLUSIONS

Overall, the results confirm that the proposed hybrid Mueller matrix imaging and AI framework provides a simple and effective approach for HB virus detection.

Characterization of Mueller matrix elements for classifying human skin cancer utilizing random forest algorithm

SIGNIFICANCE

The Mueller matrix decomposition method is widely used for the analysis of biological samples. However, its presumed sequential appearance of the basic optical effects (e.g., dichroism, retardance, and depolarization) limits its accuracy and application.

AIM

An approach is proposed for detecting and classifying human melanoma and non-melanoma skin cancer lesions based on the characteristics of the Mueller matrix elements and a random forest (RF) algorithm.

APPROACH

In the proposal technique, 669 data points corresponding to the 16 elements of the Mueller matrices obtained from 32 tissue samples with squamous cell carcinoma (SCC), basal cell carcinoma (BCC), melanoma, and normal features are input into an RF classifier as predictors.

RESULTS

The results show that the proposed model yields an average precision of 93%. Furthermore, the classification results show that for biological tissues, the circular polarization properties (i.e., elements m44, m34, m24, and m14 of the Mueller matrix) dominate the linear polarization properties (i.e., elements m13, m31, m22, and m41 of the Mueller matrix) in determining the classification outcome of the trained classifier.

CONCLUSIONS

Overall, our study provides a simple, accurate, and cost-effective solution for developing a technique for classification and diagnosis of human skin cancer.

Morphology-Dependent Ambient-Condition Growth of Perovskite Nanocrystals for Enhanced Stability in Photoconversion Device

CsPbBr₃ perovskite nanocrystals with two different dimensionalities were synthesized at different temperatures and then integrated as optoelectronic transducers into transistor-type photoconversion devices. Postsynthesis transformation was observed for two-dimensional (2D) nanoplatelets, while the transformation was rarely found in 3D nanocubes. At ambient temperature and pressure, neighboring nanoplatelets made facet-to-facet contact and then fused into larger 2D nanoplatelets (2-5 times) without defects. The coalescence of 2D nanoplatelets at the ambient condition lowered the density of defects at the surface of the nanocrystals and thus could facilitate effective and stable photoconversion behavior in the nanocrystal film integrated into the device. Consequently, the ambient-condition aging of 2D nanoplatelets on device substrate led to 3 times higher retention in photoconversion performance. Importantly, these results provide a new concept of how perovskite nanocrystals can be integrated into a device for enhanced stability in device performance.

Surfactant-in-Polymer Templating for Fabrication of Carbon Nanofibers with Controlled Interior Substructures: Designing Versatile Materials for Energy Applications

A simple, scalable, surfactant-in-polymer templating approach is demonstrated to create controlled long-range secondary substructures in a primary structure. A metal bis(2-ethylhexyl) sulfosuccinate (MAOT) as the surfactant is shown to be capable of serving as a sacrificial template and metal precursor in carbon nanofibers. The low interfacial tension and controllable dimensions of the MAOT are maintained in the solid-phase polymer, even during electrospinning and heat-treatment processes, allowing for the long-range uniform formation of substructures in the nanofibers. The MAOT content is found to be a critical parameter for tailoring the diameter of the nanofibers and their textural properties, such as size and volume of interior pores. The metal counterion species in the MAOT determine the introduction of metallic phases in the nanofiber interior. The incorporation of MAOT with Na as the counterion into the polymer phase leads to the formation of a built-in pore structure in the nanofibers. In contrast, MAOT with Fe as a counterion generates unique iron-in-pore substructures in the nanofibers (FeCNFs). The FeCNFs exhibit outstanding charge storage and water splitting performances. As a result, the MAOT-in-polymer templating approach can be extended to combinations of various metal precursors and thus create desirable functionalities for different target applications.

Influences of copper-potassium ion exchange process on the optical bandgaps and spectroscopic properties of Cr3+/Yb3+ co-doped in lanthanum aluminosilicate glasses

In this study, lanthanum aluminosilicate glasses with compositions of 45SiO2-20Al2O3-12.5LaF3-10BaF2-9K2O-1Cr2O3-2.5Yb2O3 (SALBK) were prepared using the conventional melting method and copper-potassium ion exchange process. Influences of the ion exchange process between copper and potassium on the visible, upconversion, and near-infrared luminescence spectra of Cr3+/Yb3+ co-doped under excitations of 343, 490, and 980 nm LD were investigated. The EDS analysis of SALBK glasses was measured to confirm the presence of atoms in the glasses. The values of direct and indirect bandgaps of Cr3+/Yb3+ co-doped SALBK glasses were calculated and analyzed. Besides, the energy exchange processes between Cu+, Cu2+ ions, and Cr3+, Yb3+ ions were also proposed and discussed.

[The State of The Jak/Stat Pathway Affects the Sensitivity of TumorCells to Oncolytic Enteroviruses]

A test of the sensitivity of seven colon cancer cell lines to a panel of 12 nonpathogenic human enteroviruses revealed significant differences in the ability of tumor cells to become infected and replicate different viral strains. Among the factors that can affect the sensitivity of cells to viruses are differences in the state of the mechanisms of antiviral protection, associated with a reaction to type I interferons. Using the two colon cancer cell lines CaCo2 and LIM1215 as a model, significant differences were revealed in the ability of cells to defend themselves against virus infection after 16 hours of treatment with 1000 units/mL of interferon-alpha. To study the effect of the state of the interferon response system, represented by the Jak/STAT signaling pathway, on the sensitivity of cells to different strains of enteroviruses, HEK293T cell lines were used. These are capable of supporting replication of each of the tested enteroviruses, as well as maintaining the ability to protect against viral infection after the treatment with interferon. Using the CRISPR/Cas9 system, HEK293T sublines with knockouts of the IFNAR1 and STAT2 genes were obtained. The sensitivity of control and knockout cells to infection with five strains of enteroviruses and the vesicular stomatitis virus was analyzed. It was noted that knockout of the IFNAR1 and STAT2 genes resulted in an increased sensitivity to all tested viruses. In knockout cells, the levels of reproduction of the vaccine derived of poliovirus type 1, Echoviruses 7 and 30, and Coxsackie viruses B5 and A7 were also significantly increased in comparison with the control HEK293T cells. Thus, deficiencies in the Jak/STAT signaling pathway in tumor cells lead to an overall increase in the sensitivity to oncolytic viruses.

Anomalous restoration of sp2 hybridization in graphene functionalization

The functionalization of nanocarbon materials such as graphene has attracted considerable attention over the past decades. In this work, we designed and synthesized a unique N-heterocyclic carbene compound with a pyrene tail group (NHCp) to investigate how carbene species can be used for the functionalization of graphene. Although the carbene moiety of NHCp has the ability to covalently bond to graphene, the pyrene tail can noncovalently interact with graphene and allows monitoring its surrounding microenvironment. The major characteristics of the resulting nanohybrids were highly dependent on the type of graphene and the NHCp-to-graphene weight ratio. Importantly, despite the covalent functionalization of graphene, an anomalous decrease in the intensity of the Raman D peak and improved conductivity were observed for the nanohybrids. It was found that the covalent bond of NHCp to the graphene edge may allow the hybridization of their orbitals, which affects electronic energy levels and alters the double resonance process that originates the D peak at the edge defect. Importantly, the NHCp compound can act as a π acceptor (not just as a σ donor) via the NHCp-graphene covalent bridge. This is the first report showing that the concept of π-backdonation can be realized in two-dimensional materials, such as graphene, and rationally designed carbene molecules can functionalize graphene without losing their beneficial sp2 hybridization characteristics.

Exfoliation of 2D Materials for Energy and Environmental Applications

The fascinating properties of single-layer graphene isolated by mechanical exfoliation have inspired extensive research efforts toward two-dimensional (2D) materials. Layered compounds serve as precursors for atomically thin 2D materials (briefly, 2D nanomaterials) owing to their strong intraplane chemical bonding but weak interplane van der Waals interactions. There are newly emerging 2D materials beyond graphene, and it is becoming increasingly important to develop cost-effective, scalable methods for producing 2D nanomaterials with controlled microstructures and properties. The variety of developed synthetic techniques can be categorized into two classes: bottom-up and top-down approaches. Of top-down approaches, the exfoliation of bulk 2D materials into single or few layers is the most common. This review highlights chemical and physical exfoliation methods that allow for the production of 2D nanomaterials in large quantities. In addition, remarkable examples of utilizing exfoliated 2D nanomaterials in energy and environmental applications are introduced.

Zero reduction luminescence of aqueous-phase alloy core/shell quantum dots via rapid ambient-condition ligand exchange

Quantum dots (QDs) have been widely studied as promising materials for various applications because of their outstanding photoluminescence (PL). Although ligand exchange methods for QDs have been developed over two decades, the PL quantum yield (QY) of aqueous phase QDs is still lower than that of their organic phase and the mechanism of quenching has not been clearly understood. In this study, we demonstrate for the first time that 3-mercaptopropionic-capped CdZnSeS/ZnS core/shell QDs obtained via ligand exchange in a ternary solvent system containing chloroform/water/dimethyl sulfoxide can enable the fast phase transfer and zero reduction of PL under ambient condition. The new solvent system allows the ligand-exchanged QDs to exhibit enhanced QYs up to 8.1% of that of the organic-phase QDs. Based on both theoretical calculation and experiment, it was found that control over the physical/chemical perturbation between the organic/aqueous phases by choosing appropriate solvents for the ligand exchange process is very important to preserve the optical properties of QDs. We believe that our new technologies and theoretical knowledge offer opportunities for the future design and optimization of highly stable and highly luminescent aqueous-phase QDs for various applications.

Electrical monitoring of photoisomerization of block copolymers intercalated into graphene sheets

Insulating polymers have received little attention in electronic applications. Here, we synthesize a photoresponsive, amphiphilic block copolymer (PEO-b-PVBO) and further control the chain growth of the block segment (PVBO) to obtain different degrees of polymerization (DPs). The benzylidene oxazolone moiety in PEO-b-PVBO facilitated chain-conformational changes due to photoisomerization under visible/ultraviolet (UV) light illumination. Intercalation of the photoresponsive but electrically insulating PEO-b-PVBO into graphene sheets enabled electrical monitoring of the conformational change of the block copolymer at the molecular level. The current change at the microampere level was proportional to the DP of PVBO, demonstrating that the PEO-b-PVBO-intercalated graphene nanohybrid (PGNH) can be used in UV sensors. Additionally, discrete signals at the nanoampere level were separated from the first derivative of the time-dependent current using the fast Fourier transform (FFT). Analysis of the harmonic frequencies using the FFT revealed that the PGNH afforded sawtooth-type current flow mediated by Coulomb blockade oscillation.

Block copolymers are electrically insulating and therefore characterization with electrical or electrochemical methods is not possible. Here, the authors demonstrate electrical monitoring of the photoisomerization transition in a benzylidene oxazolone block co-polymer intercalated into graphene sheets.

Correction: Pine cone mold: a toolbox for fabricating unique metal/carbon nanohybrid electrocatalysts

Correction for 'Pine cone mold: a toolbox for fabricating unique metal/carbon nanohybrid electrocatalysts' by Hyunwoo Han et al., Nanoscale, 2019, DOI: 10.1039/c9nr06794a.

Pine cone mold: a toolbox for fabricating unique metal/carbon nanohybrid electrocatalysts

Nature presents delicate and complex materials systems beyond those fathomable by humans, and therefore, extensive effort has been made to utilize or mimic bio-materials and bio-systems in various fields. Biomass, an inexhaustible natural materials source, can also present good opportunities for the development of unprecedented, advanced materials and processing systems. Herein, we demonstrate the use of pine cones as a biomass mold for creating new and useful metal/carbon nanohybrids (MCNHs). The inherent water-induced folding actuation of the cone scales allows the casting of an aqueous solution of a single metal precursor or a binary metal mixture into the cone mold by simply immersing the cone in the solution. The cone actively absorbs aqueous-phase metal precursors through the bract scales and the precursor ions introduced into the cone are anchored to the functional groups of the interior tissues of the cone. Subsequent heat treatment successfully led to the formation of unique MCNHs. Iron, manganese, and cobalt were employed as model metals, binary mixtures of which were also cast into the cone mold to create further versatile MCNHs. Nanoparticulate metals were formed on the carbon supports, where the size, size distribution, and crystallinity of the nanoparticles were highly dependent on the identity of the single-component precursor and the combination of precursors. Consequently, the electrochemical activity of the MCNHs also depended on which metal precursors were cast into the cone mold. The MCNH prepared from the mixture of iron and manganese precursors (M_FeMnCNH) showed the best electrochemical activity. As model applications, M_FeMnCNH was applied to electrode materials for electrochemical charge storage and the oxygen evolution reaction. An electrochemical capacitor cell based on the M_FeMnCNH electrodes showed excellent performance with energy densities of 38.7-54.2 W h kg^-1 at power densities of 16 000-160 kW kg^-1. In addition, M_FeMnCNH demonstrated a low overpotential of 464 mV and fast kinetics with a Tafel slope of 64.6 mV dec^-1 as an electrocatalyst for the oxygen evolution reaction in 1.0 M KOH. These results substantiate that pine cones as a biomass mold show great promise for creating versatile MCNHs through further combination of various precursors.

Combining SWNT and Graphene in Polymer Nanofibers: A Route to Unique Carbon Precursors for Electrochemical Capacitor Electrodes

It is important to fabricate nanostructured architectures comprised of functional components for a wide variety of applications because precise structural control in the nanometer regime can yield unprecedented, fascinating properties. Owing to their well-defined microstructural characteristics, it has been popular to use carbon nanospecies, such as nanotubes and graphene, in fabricating nanocomposites and nanohybrids. Nevertheless, it still remains hard to control and manipulate nanospecies for specific applications, thus preventing their commercialization. Herein, first, we report unique one-dimensional nanoarchitectures with meso-/macropores, consisting of single-walled nanotubes (SWNTs), graphene, and polyacrylonitrile, in which poly(vinyl alcohol) was employed as a dispersing agent and sacrificial porogen. One-dimensional SWNTs and two-dimensional graphene pieces were combined in the confined interior space of electrospun nanofibers, which led to unique microstructural characteristics such as enhanced ordering of SWNTs, graphene pieces, and polymer chains in the nanofiber interior. Next, the SWNT/graphene-in-polymer nanofiber (SGPNF) structures were converted into carbonized products (SGCNFs) with effective porosity and tunable electrochemical properties. Similar to SGPNFs, the microstructural and electrical properties of the SGCNFs depended on the incorporated amount of SWNT and graphene. At higher SWNT content, the mesopore volume proportion and specific discharge capacitance of the SGCNFs increased by max. 63 and 598%, respectively. The SGCNFs showed strong potential as a high-performance electrode material for electrochemical capacitors (max. capacitance: nonactivated ∼390 F g^-1 and activated ∼750 F g^-1). Flexible, all solid-state capacitor cells based on SGCNFs were also successfully demonstrated as a model application. The SGCNFs can be further functionalized by various methods, which will impart attractive properties for extended applications.

Physical exfoliation of graphene and molybdenum disulfide sheets using conductive polyaniline: an efficient route for synthesizing unique, random-layered 3D ternary electrode materials

Unique ternary graphene/MoS₂/PANI nanoarchitectures with beneficial properties are synthesized via a simple, physical exfoliation approach.

Nanostructured mesophase electrode materials: modulating charge-storage behavior by thermal treatment

3D nanostructured carbonaceous electrode materials with tunable capacitive phases were successfully developed using graphene/particulate polypyrrole (PPy) nanohybrid (GPNH) precursors without a separate process for incorporating heterogeneous species. The electrode material, namely carbonized GPNHs (CGPNHs) featured a mesophase capacitance consisting of both electric double-layer (EDL) capacitive and pseudocapacitive elements at the molecular level. The ratio of EDL capacitive element to pseudocapacitive element (E-to-P) in the mesophase electrode materials was controlled by varying the PPy-to-graphite weight (P_w/G_w) ratio and by heat treatment (T_H), which was demonstrated by characterizing the CGPNHs with elemental analysis, cyclic voltammetry, and a charge/discharge test. The concept of the E-to-P ratio (EPR) index was first proposed to easily identify the capacitive characteristics of the mesophase electrode using a numerical algorithm, which was reasonably consistent with the experimental findings. Finally, the CGPNHs were integrated into symmetric two-electrode capacitor cells, which rendered excellent energy and power densities in both aqueous and ionic liquid electrolytes. It is anticipated that our approach could be widely extended to fabricating versatile hybrid electrode materials with estimation of their capacitive characteristics.

A Solution-Processable, Nanostructured, and Conductive Graphene/Polyaniline Hybrid Coating for Metal-Corrosion Protection and Monitoring

A smart and effective anticorrosive coating consisting of alternating graphene and polyaniline (PANI) layers was developed using top-down solution processing. Graphite was exfoliated using sonication assisted by polyaniline to produce a nanostructured, conductive graphene/polyaniline hybrid (GPn) in large quantities (>0.5 L of 6 wt% solution in a single laboratory-scale process). The GPn was coated on copper and exhibited excellent anticorrosion protection efficiencies of 46.6% and 68.4% under electrochemical polarization in 1 M sulfuric acid and 3.5 wt% sodium chloride solutions, chosen as chemical and seawater models, respectively. Impedance measurements were performed in the two corrosive solutions, with the variation in charge transfer resistance (R ct) over time indicating that the GPn acted as an efficient physical and chemical barrier preventing corrosive species from reaching the copper surface. The GPn-coated copper was composed of many PANI-coated graphene planes stacked parallel to the copper surface. PANI exhibits redox-based conductivity, which was facilitated by the high conductivity of graphene. Additionally, the GPn surface was found to be hydrophobic. These properties combined effectively to protect the copper metal against corrosion. We expect that the GPn can be further applied for developing smart anticorrosive coating layers capable of monitoring the status of metals.

Electrical and Electrochemical Properties of Conducting Polymers

Conducting polymers (CPs) have received much attention in both fundamental and practical studies because they have electrical and electrochemical properties similar to those of both traditional semiconductors and metals. CPs possess excellent characteristics such as mild synthesis and processing conditions, chemical and structural diversity, tunable conductivity, and structural flexibility. Advances in nanotechnology have allowed the fabrication of versatile CP nanomaterials with improved performance for various applications including electronics, optoelectronics, sensors, and energy devices. The aim of this review is to explore the conductivity mechanisms and electrical and electrochemical properties of CPs and to discuss the factors that significantly affect these properties. The size and morphology of the materials are also discussed as key parameters that affect their major properties. Finally, the latest trends in research on electrochemical capacitors and sensors are introduced through an in-depth discussion of the most remarkable studies reported since 2003.

Abstract P4-13-09: Clinical effectiveness of everolimus and exemestane in advanced breast cancer patients from Asia and Africa: First efficacy and updated safety results from the phase IIIb EVEREXES study

Background

BOLERO-2 phase III trial established the efficacy of everolimus (EVE) plus exemestane (EXE) for the treatment of postmenopausal patients with hormone receptor (HR)-positive, HER2-negative, advanced breast cancer (aBC). However, in this study only a minority (<10%) of patients were recruited from African and Asia Pacific countries. Considering the potential effects of ethnic and cultural differences on treatment effectiveness, it remains compelling to confirm the safety and efficacy profile of EVE+EXE in these populations.

Methods

EVEREXES is an open-label phase IIIb, single arm, multi-center trial, which from March 2013 to October 2014 enrolled 232 post-menopausal, HR-positive and HER2-negative, aBC patients previously treated with aromatase inhibitors, across 13 countries in Asia Pacific, Middle East, North and South Africa, with a significant majority of patients being of Asian ethnicity (196, 84.5%). Its primary objective was to investigate the safety and tolerability profile of EVE+EXE. Secondary objectives were the evaluation of efficacy (assessed by PFS, ORR, and CBR based on RECIST 1.1 criteria) and change in ECOG performance status.

Results

At data cut off of 31st of January 2015, at a median follow up of 11.7 months, median PFS for the ITT population was 9.5 months [9.2-11.6 months], based on local assessment, with the observation of 1 (0.4%) CR and 35 (15.4%) PR. Regarding safety and tolerability, a majority (81.1%) of grade (G) 1/2 adverse events (AEs) was reported. In particular, the following pattern was observed in terms of % of patients who developed G1/G2/G3 mTOR-inhibition induced AEs: stomatitis (36.1, 13.7, 10.6), rash (21.6/6.2/0), fatigue (10.6, 4.4, 2.2), hyperglycemia (6.2, 11.5, 7.0), weight decrease (7.5, 7, 0.9), pneumonitis (5.7, 7, 0.9). No Grade 4 AEs related to EVE+EXE treatment were observed, with exception of one case of non infectious pneumonitis (0.4%). Median dose intensity of everolimus was 9.2 mg/day.

Conclusions

Efficacy and safety results from EVEREXES trial further confirm the role of EVE+EXE for the treatment of HR+/Her2- advanced BC patients in Eastern countries. Results were consistent with data previously reported in BOLERO-2 trial.

Citation Format: Im Y-H, Uslu R, Lee KS, Nagarkar R, Sohn J, Sevinc A, Altundag K, Chang Y-C, Abdel-Razeq H, Im S-A, Jeong J, Park HY, Arpornwirat W, Bastick P, Le TH, Ocak Arikan O, Xue HL, Canatar A, Valenti R, Kim S-B. Clinical effectiveness of everolimus and exemestane in advanced breast cancer patients from Asia and Africa: First efficacy and updated safety results from the phase IIIb EVEREXES study. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P4-13-09.

Genetic association between leg conformation in young pigs and sow longevity

Longevity is important in pig production with respect to both economic and ethical aspects. Direct selection for longevity might be ineffective because 'true' longevity can only be recorded when a sow has been culled or died. Thus, indirect selection for longevity using information from other traits that can be recorded early in life and are genetically correlated with longevity might be an alternative. Leg conformation has been included in many breeding schemes for a number of years. However, proving that leg conformation traits are good early indicators for longevity still remains. Our aim was to study genetic associations between leg conformation traits of young (5 months; 100 kg) Swedish Yorkshire pigs in nucleus herds and longevity traits of sows in nucleus and multiplier herds. Data included 97 533 animals with information on conformation (Movement and Overall score) recorded at performance testing and 26 962 sows with information on longevity. The longevity traits were as follows: stayability from 1st to 2nd parity, lifetime number of litters and lifetime number of born alive piglets. Genetic analyses were performed with both linear models using REML and linear-threshold models using Bayesian methods. Heritabilities estimated using the Bayesian method were higher than those estimated using REML, ranging from 0.10 to 0.24 and 0.07 to 0.20, respectively. All estimated genetic correlations between conformation and longevity traits were significant and favourable. Heritabilities and genetic correlations between conformation and longevity indicate that selection on leg conformation should improve sow longevity.

Comparison of experimental infection with northern and southern Vietnamese strains of highly pathogenic porcine reproductive and respiratory syndrome virus

The aim of this study was to compare the virulence of northern and southern Vietnamese strains of highly pathogenic porcine reproductive and respiratory syndrome virus (HP-PRRSV) as assessed by the level of viral replication, gross and microscopical lung lesions and virus distribution in experimentally infected pigs. The northern and southern Vietnamese HP-PRRSV strains share 96.7% (non-structural protein 2) and 99.3% (open reading frame 5) nucleotide identity. On experimental challenge, approximately 50% of pigs infected with northern Vietnamese HP-PRRSV died, while death was not observed in any pigs infected with southern Vietnamese HP-PRRSV. Mean viral titres (expressed as log(10)TCID(50)/ml) were significantly (P <0.05) higher in sera and lungs from pigs infected with the northern Vietnamese HP-PRRSV than from those infected with the southern Vietnamese strain at multiple time points. Lung lesion scores and PRRSV antigen within pulmonary and lymphoid lesions were significantly (P <0.05) higher in pigs infected with northern Vietnamese HP-PRRSV than in those receiving southern Vietnamese HP-PRRSV at multiple time points. PRRSV antigens were observed in cardiac myocytes, gastric and renal tubular epithelial cells and astrocytes and microglia of white matter in the brain from pigs infected with the northern Vietnamese HP-PRRSV strain only. Thus, genetic similarity did not predict the degree of virulence of these strains. Northern Vietnamese HP-PRRSV was more virulent and had extended tissue tropism when compared with southern Vietnamese HP-PRRSV.

Assessment of a 27-kDa antigen in enzyme-linked immunosorbent assay for the diagnosis of fasciolosis in Vietnamese patients

Fasciolosis has emerged as an important zoonotic disease in many parts of the world. In recent years, an increasing number of human cases were reported in Vietnam. In this study, the 27-kDa component protein from the excretory/secretory production of adult Fasciola gigantica, purified by high performance liquid chromatography, was assessed in an enzyme-linked immunosorbent assay (ELISA) to detect antibodies against Fasciola spp. for diagnosis of human fasciolosis. The ELISA showed a high sensitivity (100%) and specificity (97.67%) when tested on patients with fasciolosis, other parasitic infections, cholangiocarcinoma and on healthy controls. The assay was applied for diagnosis on 143 patients in the Viet Duc-Hanoi hospital who presented with clinical signs of liver disease and lesions in their livers as shown by imaging techniques. Antibodies were found in 37 (25.9%) of these patients, of whom only 3 shed Fasciola eggs in their stools (2.1%). The excellent response to triclabendazole treatment of 37 sero-positive patients confirmed the diagnosis of fasciolosis. This study demonstrated the diagnostic potential for human fasciolosis of the 27-kDa antigen ELISA. Fasciolosis should be considered in the differential diagnosis of hepatic disease in Vietnam.

Hypertension and albuminuria in chronic kidney disease mapped to a mouse chromosome 11 locus

Chronic kidney disease (CKD) is a key cause of hypertension and a potent independent risk for cardiovascular disease. Epidemiological studies suggest a strong genetic component determining susceptibility for renal disease and, by inference, the associated cardiovascular risk. With a subtotal nephrectomy model of kidney disease, we found the 129S6 mouse strain to be very susceptible to the development of hypertension, albuminuria, and kidney injury, whereas the C57BL/6 strain is relatively resistant. Accordingly, we set out to map quantitative trait loci conferring susceptibility to hypertension and albuminuria using this model with F2 mice. We found significant linkage of the blood pressure trait to two loci. At D11Mit143, mice homozygous for the 129S6 allele had significantly higher systolic blood pressure than mice heterozygous or homozygous for the C57BL/6 allele. Similarly, at D1Mit308, there was an excellent correlation between genotype and the blood pressure phenotype. The effect of the chromosome 11 locus was verified with a separate cohort of F2 mice. For the albuminuria trait, a significant locus was found at D11Mit143, which overlaps the blood pressure trait locus. Our studies have identified a region spanning approximately 8 cM on mouse chromosome 11 that is associated with susceptibility to hypertension and albuminuria in CKD.

The phylogeny of the Schistosomatidae based on three genes with emphasis on the interrelationships of Schistosoma Weinland, 1858

Schistosomes are digenean flukes, parasitic of birds, mammals and crocodiles. The family Schistosomatidae contains species of considerable medical and veterinary importance, which cause the disease schistosomiasis. Previous studies, both morphological and molecular, which have provided a good deal of information on the phylogenetics of this group, have been limited in the number of species investigated or the type or extent of molecular data used. This paper presents the most comprehensive phylogeny to date, based on the sequences of 3 genes, complete ribosomal small subunit rRNA and large ribosomal subunit rRNA, and mitochondrial cytochrome oxidase 1, sequenced from 30 taxa including at least 1 representative from 10 of the 13 known genera of the Schistosomatidae and 17 of the 20 recognized Schistosoma species. The phylogeny is examined using morphological characters, intermediate and definitive host associations and biogeography. Theories as to the origins and spread of Schistosoma are also explored. The principal findings are that Ornithobilharzia and Austrobilharzia form a sister group to the Schistosoma; mammalian schistosomes appear paraphyletic and 2 Trichobilharzia species, T. ocellata and T. szidati, seem to be synonymous. The position of Orientobilharzia within the Schistosoma is confirmed, as is an Asian origin for the Schistosoma, followed by subsequent dispersal through India and Africa.

Revisiting the question of limited genetic variation within Schistosoma japonicum

Recent electrophoretic data have indicated that Schistosoma japonicum in mainland China may be a species complex, with the existence of a cryptic species being predicted from the analysis of schistosome populations from Sichuan province. To investigate the Sichuan form of S. japonicum, 4.9 kbp of mitochondrial DNA from each of three samples of the parasite from China (two from Sichuan and one from Hunan) and one from Sorsogon in the Philippines were amplified, sequenced and characterized. The sequence data were compared with those from the related South-east Asian species of S. mekongi (Khong Island, Laos) and S. mlayensis (Baling, Malaysia) and that from S. japonicm from Anhui (China). At both the nucleotide and amino-acid levels, the variation among the five S. japonicum samples was limited (< 1%). This was consistent with the conclusions drawn from previous molecular studies, in which minimal variation among S. japonicum populations was also detected. In contrast, S. mekongi and S. malayensis, species recognized as separate but closely related, differ from each other by about 10%, and each differs by 25%-26% from S. japonicum. Phylogenetic trees provided a graphic representation of these differences, showing all S. japonicum sequences to be very tightly clustered and distant from S. mekongi and S. malayensis, the last two being clearly distinct from each other. The results thus indicate no significant intra-specific genetic variation among S. japonicum samples collected from different geographical areas and do not support the idea of a distinct form in Sichuan.

Complete mitochondrial genomes confirm the distinctiveness of the horse-dog and sheep-dog strains of Echinococcus granulosus

Unlike other members of the genus, Echinococcus granulosus is known to exhibit considerable levels of variation in biology, physiology and molecular genetics. Indeed, some of the taxa regarded as 'genotypes' within E. granulosus might be sufficiently distinct as to merit specific status. Here, complete mitochondrial genomes are presented of 2 genotypes of E. granulosus (G1-sheep-dog strain: G4-horse-dog strain) and of another taeniid cestode, Taenia crassiceps. These genomes are characterized and compared with those of Echinococcus multilocularis and Hymenolepis diminuta. Genomes of all the species are very similar in structure, length and base-composition. Pairwise comparisons of concatenated protein-coding genes indicate that the G1 and G4 genotypes of E. granulosus are almost as distant from each other as each is from a distinct species, E. multilocularis. Sequences for the variable genes atp6 and nad3 were obtained from additional genotypes of E. granulosus, from E. vogeli and E. oligarthrus. Again, pairwise comparisons showed the distinctiveness of the G1 and G4 genotypes. Phylogenetic analyses of concatenated atp6, nad1 (partial) and cox1 (partial) genes from E. multilocularis, E. vogeli, E. oligarthrus, 5 genotypes of E. granulosus, and using T. crassiceps as an outgroup, yielded the same results. We conclude that the sheep-dog and horse-dog strains of E. granulosus should be regarded as distinct at the specific level.

Complete DNA sequence and gene organization of the mitochondrial genome of the liverfluke, Fasciola hepatica L. (Platyhelminthes; Trematoda)

The complete nucleotide sequence of the mitochondrial (mt) DNA molecule of the liverfluke, Fasciola hepatica (phylum Platyhelminthes, class Trematoda, family Fasciolidae), was determined. It comprises 14462 bp, contains 12 protein-encoding, 2 ribosomal and 22 transfer RNA genes, and is the second complete flatworm (and the first trematode) mitochondrial sequence to be described in detail. All of the genes are transcribed from the same strand. Of the genes typically found in mitochondrial genomes of eumetazoans, only atp8 is absent. The nad4L and nad4 genes overlap by 40 nt. Most intergenic sequences are very short. Two larger non-coding regions are present. The longer one (817 nt) is located between trnG and cox3 and consists of 8 identical tandem repeats of 85 nt, rich in G and C, followed by 1 imperfect repeat. The shorter non-coding region (187 nt) exhibits no special features and is separated from the longer region by trnG. The gene arrangement resembles that of some other trematodes including the eastern Asian Schistosoma species (and cyclophyllidean cestode species) but it is strikingly different from that of the African schistosomes, represented by Schistosoma mansoni. The genetic code is as inferred previously for flatworms. Transfer RNA genes range in length from 58 to 70 nt, their products producing characteristic 'clover leaf' structures, except for tRNA(S(UNC)) and tRNA(S(AGN)) lacking the DHU arm.

Mitochondrial gene content, arrangement and composition compared in African and Asian schistosomes

Complete sequences were obtained for the coding portions of the mitochondrial (mt) genomes of Schistosoma mansoni (NMRI strain, Puerto Rico; 14 415 bp), S. japonicum (Anhui strain, China; 14 085 bp) and S. mekongi (Khong Island, Laos; 14 072 bp). Each comprises 36 genes: 12 protein-encoding genes (cox1-3, nad1-6, nad4L, atp6 and cob); two ribosomal RNAs, rrnL (large subunit rRNA or 16S) and rrnS (small subunit rRNA or 12S); as well as 22 transfer RNA (tRNA) genes. The atp8 gene is absent. A large segment (9.6 kb) of the coding region (comprising 14 tRNAs, eight complete and two incomplete protein-encoding genes) for S. malayensis (Baling, Malaysian Peninsula) was also obtained. Each genome also possesses a long non-coding region that is divided into two parts (a small and a large non-coding region, the latter not fully sequenced in any species) by one or more tRNAs. The protein-encoding genes are similar in size, composition and codon usage in all species except for cox1 in S. mansoni (609 aa) and cox2 in S. mekongi (219 aa), both of which are longer than homologues in other species. An unexpected finding in all the Schistosoma species was the presence of a leucine zipper motif in the nad4L gene. The gene order in S. mansoni is strikingly different from that seen in the S. japonicum group and other flatworms. There is a high level of identity (87-94% at both the nucleotide and amino acid levels) for all protein-encoding genes of S. mekongi and S. malayensis. The identity between genes of these two species and those of S. japonicum is less (56-83% for amino acids and 73-79% for nucleotides). The identity between the genes of S. mansoni and the Asian schistosomes is far less (33-66% for amino acids and 54-68% for nucleotides), an observation consistent with the known phylogenetic distance between S. mansoni and the other species.

Molecular analysis of beta-thalassemia in South Vietnam

The high prevalence of beta-thalassemia in Southeast Asia is a major public health problem. Development of genetic counseling and prenatal diagnosis programs is a priority. To provide the groundwork for such programs in South Vietnam, we determined the spectrum of beta-thalassemia mutations in 35 severely affected patients and their relatives. We identified six different beta-thalassemia alleles (five beta(0) and one beta(+) mutations), in addition to the common mutation at codon 26 (GAG --> AAG) responsible for Hb E. These data provide insights into the distribution of beta-thalassemia alleles in the Vietnamese population.

A leucine zipper protein of mitochondrial origin

Sequence-specific DNA-binding proteins are characterised by short coiled-coil structural domains classified as zinc finger/RING finger, leucine zipper (L-Zip) or helix-loop-helix (HLH) motifs. The L-Zip proteins are defined by a pattern of at least four leucine (L) residues repeated every seventh amino acid that mediates protein dimerisation through the formation of parallel alpha-helical dimers. Usually the zipper is incorporated into a helix-loop-helix conformation called the basic helix-loop-helix-leucine zipper (bHLH/Zip). To date, all of the several hundred proteins reported as containing the L-Zip and/or bHLH/Zip motifs are nuclear-encoded. No leucine zipper polypeptide has, hitherto, been reported as mitochondrial in origin. Here we report such a polypeptide, the nicotinamide dehydrogenase subunit 4L (nad4L). We first identified this in human blood flukes of the genus Schistosoma (phylum Platyhelminthes; class Trematoda) but show that this is a common feature in other eucaryotes as well. Therefore, in addition to their well recognised role in oxidative phosphorylation, nad4L proteins may be pivotally involved in a range of other biological processes such as transcription and/or replication activation or as signal transmitters in communication with the nucleus and other cellular organelles. This may indicate a link between transcription regulation and respiration in mitochondria. We have also identified L-Zip-like motifs in nuoK, the procaryotic equivalent of the nad4L mitochondrial protein.

Functional MRI of human auditory cortex using block and event-related designs

fMRI of human auditory cortex response to sinusoidal tones of 200, 1000, and 3000 Hz was evaluated using block design and conventional and "silent" event-related designs. Conventional event-related fMRI revealed the timecourse of the BOLD response (approximately 5 sec to peak, approximately 4 sec full-width-half-max, and approximately 14 sec recovery to baseline). Both event-related, but not block, designs provided evidence for tonotopic organization in auditory cortex. Sources of low-frequency activation were more lateral and anterior than the sources of high-frequency activation (P < or = 0.05). In the block designs, repeated rapid stimulus presentation and the co-incidence of scanner noise preclude definition of tonotopic organization revealed in event-related approaches. Magn Reson Med 45:254-260, 2001.

Mitochondrial genomes of human helminths and their use as markers in population genetics and phylogeny

To date, over 100 complete metazoan mitochondrial (mt) genomes of different phyla have been reported. Here, we briefly summarise mt gene organisation in the Metazoa and review what is known of the mt genomes of nematodes and flatworms parasitic in humans. The availability of complete or almost complete mtDNA sequences for several parasitic helminths provides a rich source of genetic markers for phylogenetic analysis and study of genetic variability in helminth groups. Examples of the application of mtDNA in studies on Ascaris, Onchocerca, Schistosoma, Fasciola, Paragonimus, Echinostoma, Echinococcus and Taenia are described.

Application of micellar electrokinetic chromatography for the separation of retinoids

The applicability of micellar electrokinetic chromatography (MEKC) using sodium dodecylsulphate (SDS) as pseudo-stationary phase for the separation of five retinoids (retinol, retinal, retinyl acetate, retinyl palmitate, retinoic acid), was investigated. The effects of the acetonitrile content, the SDS concentration, the pH and the addition of Brij 35 to the background electrolyte on the migration behaviour of the retinoids were determined. It was found that the effective mobilities of retinol, retinal and retinyl acetate could be easily regulated through the ACN content and the SDS concentration of the BGE. The electrophoretic behaviour of the very hydrophobic retinyl palmitate was abnormal. Under various conditions this compound showed up as a late, very sharp peak. A strong indication was found that the retinyl palmitate forms a stable, charged complex with SDS during sample preparation. The mobility of the retinyl palmitate peak could be regulated, independently from the other peaks, through the Brij concentration of the BGE. Using a running buffer consisting of Tris buffer (pH 8), 20 mmol l(-1) SDS, 1 mmol l(-1) Brij 35 and 35% (v/v) acetonitrile, a complete separation of the five retinoids could be realised in less than 20 min.

What can knockout mice contribute to an understanding of hypertension?

The generation of knockout mice using homologous recombination in embryonic stem cells is a powerful tool for physiologic investigations. This experimental approach has provided unique insights into the study of hypertension. Studies using knockout mice have shed new light on blood pressure regulatory mechanisms, molecular mechanisms of end-organ injury, and genetic mechanisms for hypertension. With the development of more accessible approaches for carrying out sophisticated manipulation of the mouse genome, there will be continuing utility of this technique for future studies of hypertension.

Mitochondrial DNA sequences of human schistosomes: the current status

Sequences generated from the mitochondrial genome provide useful molecular markers for defining population groups, for tracing the genetic history of an individual or a particular group of related individuals, and for constructing deep-branch taxonomic phylogenies. There is every reason to believe that the mitochondrial genome will be as valuable in studies on flatworms, such as the human schistosomes, as it has been for other taxa. To date, however, our knowledge of mitochondrial genomes of flatworms remains limited, and this review summarises the currently available information. In particular, details of the recent sequence obtained for cloned Schistosoma mansoni mitochondrial DNA fragments spanning over half of the mitochondrial genome of this species are emphasised. This and other information, available as a result of the Schistosome Genome Project, provide the basis for obtaining the complete mitochondrial DNA sequence and gene order of S. mansoni and the other human schistosomes. The availability of complete mitochondrial DNA sequences from the different species will facilitate much more in-depth study of genetic diversity and host specificity in schistosomes and the interrelationships between the various forms infecting humans and between these and other flatworms.

Mitochondrial genes of Schistosoma mansoni

Two clones, totalling 8068 bp and spanning over half of the coding region of the mitochondrial genome of Schistosoma mansoni, have been sequenced. Complete sequences are presented of the large and small ribosomal RNA subunits, CO2, ND3, ND4, ND6 and ATPase 6 genes. Incomplete sequences were found for the CO1, ND2 and CytB genes. At least 10 tRNAs were also detected and alternative structures for some of these discussed. The gene order of S. mansoni is unique and differs from that of Fasciola hepatica, the only other trematode for which any information is available.

Further evaluation of the initial negative response in functional magnetic resonance imaging

The initial negative response (i.e., the dip) in the functional MR signal at stimulus onset has aroused much interest. Such a response is consistent with optical imaging data and can be potentially mapped to generate spatially more specific maps. However, there are still controversies regarding the exact origin of the initial response. In particular, experimental reports of its echo-time dependence have been inconsistent. Furthermore, several investigators have suggested the possibility of an apparent dip that may arise artifactually when the interstimulus interval (ISI) is not sufficiently long. The present study investigates the echo-time dependence of the initial response and the effect of the ISI on the initial response. Experimental results obtained at TEs of 21, 30, and 45 msec demonstrate that the initial dip has a TE dependence that is in agreement with a T2* contrast, and thereby consistent with a blood oxygenation level-dependent origin. At an ISI of 90 sec, a statistically significant initial negative response was detected and shown to be indistinguishable from that observed at an ISI of 45 sec, which was used in our previous studies, indicating that the initial negative response observed at 4 T is not a consequence of short ISI.

Human hippocampal long-term sustained response during word memory processing

Temporal behavior of activation associated with the neural substrate of human memory function was investigated during and after an auditorily instructed word memory task using multislice functional magnetic resonance imaging. The hippocampal formation, which is involved in human memory function, displayed a long-term sustained response that persisted significantly (approximately 90 s) beyond the duration of the memory task. This sustained period was approximately two-fold longer than the duration of the post-task activation observed in auditory areas and Broca's area, which are involved in the phonological loop of the verbal working memory. These observations suggest that the hippocampal memory processing involves sustained activation in the transitional function for the long-term memory over the working memory period.

4 T-fMRI study of nonspatial shifting of selective attention: cerebellar and parietal contributions

Regional blood oxygenation in the cerebellum and posterior cerebral cortices was monitored with functional magnetic resonance imaging (fMRI) at four Tesla while 16 normal subjects performed three tasks with identical visual stimulation: fixation; attention focused upon either stimulus shape or color and sustained during blocks of trials (sustained attention); and rapid, serial shifts in attention between stimulus shape or color within blocks of trials (shifting attention). The stimuli were displayed centrally for 100 ms followed by a central fixation mark for 900 ms. Each stimulus was either a circle or a square displayed in either red or green. Attention shifting required switching between color and shape information after each target detection and occurred on average once every three seconds. Subjects pressed a response key upon detecting the target; reaction time and response accuracy were recorded. Two protocols for T2*-weighted echo-planar imaging were optimized, one with a surface coil for the cerebellum alone and the other with a volume coil for imaging both cerebellum and posterior brain structures (parietal, occipital, and part of temporal cortices). Because fMRI of the cerebellum is particularly susceptible to cardiac and respiratory fluctuations, novel techniques were applied to isolate brain activation signals from physiological noise. Functional activation maps were generated for contrasts of 1) sustained attention to color minus fixation; 2) sustained attention to shape minus fixation; and 3) shifting attention minus sustained attention (to color and shape; i.e., summed across blocks of trials). Consistent with the ease of these tasks, subjects performed with >80% accuracy during both sustained attention and shifting attention. Analysis of variance did not show significant differences in false alarms or true hits across either attentional condition. A subgroup of subjects whose performance data were recorded during ten minutes of continuous practice did not show significant changes over time. Both contrasts between the conditions of sustained attention to color or to shape as compared with the fixation condition showed significant bilateral activation in occipital and inferior temporal regions (Brodmann areas 18, 19, and 37). The anterior medial cerebellum was also significantly activated ipsilateral to the finger used for responding. The principal comparison of interest, the contrast between the condition of shifting attention and the condition of sustained attention produced significant and reproducible activation: lateral cerebellar hemisphere (ansiform lobule: Crus I Anterior and Crus I Posterior; left Crus I Posterior); cerebellar folium; posterior superior parietal lobule (R and L); and cuneus and precuneus (R and L).

Methods for assessing accuracy and reliability in functional MRI

In this paper, methods for assessing the accuracy and the reliability of functional magnetic resonance imaging techniques are presented. First, a modified receiver operating characteristic analysis is described for evaluating the accuracy of fMRI studies. With this modified approach, the true positives or the activated pixels are estimated based on highly averaged experimental data acquired with the same stimulation/task. Unlike ROC analysis based on simulated activation data, the present approach can be applied to experimentally acquired data without simplifying the activation related changes. To assess the reliability of fMRI studies, the kappa statistic was adopted for evaluating the overall agreement of functional activation maps from repeated experiments in individual subjects. To demonstrate the utility of these techniques, both the ROC analysis and the reliability assessment were applied to quantitatively evaluate the improvement in accuracy and reliability of a retrospective technique for physiological noise reduction in fMRI.