Multi-Objective Optimal Experimental Designs for ER-fMRI Using MATLAB

Designs for event-related functional magnetic resonance imaging (ER-fMRI) that help to efficiently achieve the statistical goals while taking into account the psychological constraints and customized requirements are in great demand. This is not only because of the popularity of ER-fMRI but also because of the high cost of ER-fMRI experiments; being able to collect highly informative data is crucial. In this paper, we develop a MATLAB program which can accommodate many user-specified experimental conditions to efficiently find ER-fMRI optimal designs.

Optimal experimental designs for fMRI via circulant biased weighing designs

Functional magnetic resonance imaging (fMRI) technology is popularly used in many fields for studying how the brain reacts to mental stimuli. The identification of optimal fMRI experimental designs is crucial for rendering precise statistical inference on brain functions, but research on this topic is very lacking. We develop a general theory to guide the selection of fMRI designs for estimating a hemodynamic response function (HRF) that models the effect over time of the mental stimulus, and for studying the comparison of two HRFs. We provide a useful connection between fMRI designs and circulant biased weighing designs, establish the statistical optimality of some well-known fMRI designs and identify several new classes of fMRI designs. Construction methods of high-quality fMRI designs are also given.Comment: Published at http://dx.doi.org/10.1214/15-AOS1352 in the Annals of Statistics (http://www.imstat.org/aos/) by the Institute of Mathematical Statistics (http://www.imstat.org

Maximin and maximin-efficient event-related fMRI designs under a nonlinear model

Previous studies on event-related functional magnetic resonance imaging experimental designs are primarily based on linear models, in which a known shape of the hemodynamic response function (HRF) is assumed. However, the HRF shape is usually uncertain at the design stage. To address this issue, we consider a nonlinear model to accommodate a wide spectrum of feasible HRF shapes, and propose efficient approaches for obtaining maximin and maximin-efficient designs. Our approaches involve a reduction in the parameter space and a search algorithm that helps to efficiently search over a restricted class of designs for good designs. The obtained designs are compared with traditional designs widely used in practice. We also demonstrate the usefulness of our approaches via a motivating example.Comment: Published in at http://dx.doi.org/10.1214/13-AOAS658 the Annals of Applied Statistics (http://www.imstat.org/aoas/) by the Institute of Mathematical Statistics (http://www.imstat.org

Multi-Objective Optimal Experimental Designs for ER-fMRI Using MATLAB

Designs for event-related functional magnetic resonance imaging (ER-fMRI) that help to efficiently achieve the statistical goals while taking into account the psychological constraints and customized requirements are in great demand. This is not only because of the popularity of ER-fMRI but also because of the high cost of ER-fMRI experiments; being able to collect highly informative data is crucial. In this paper, we develop a MATLAB program which can accommodate many user-specified experimental conditions to efficiently find ER-fMRI optimal designs

Tectonic evolution of the Marlborough region, South Island, New Zealand

The tectonic evolution of the Marlborough region has been studied by application of fission track thermochronology and finite element (FE) methods. The region lying within the Australian-Pacific plate boundary zone is considered to have a transcurrent fault system, known as the Marlborough Faults System (MFS). The MFS is viewed as comprising secondary transforms connecting the Hikurangi subduction margin with the main Alpine Fault oblique-slip boundary. This fault system appears to have developed sequentially towards the southeast during the past 5 million years. Consequently, the subducted Pacific plate has extended beneath the region. The FE modelling results reveal that the accommodation percentage of total displacements in Marlborough is about 85% of the total plate motion. The instantaneous displacements of the Marlborough faults show successively increase to the southeast away from the Wairau Fault. The contour of instantaneous displacements estimated by the FE modelling can be compared to the topography of Marlborough. According to the results of the FE modelling cases, the main conclusions drawn are: (1) A curved fault (the Alpine Fault) resulted from a change in the plate motion vector and is a manifestation of dextral tectonic rotation. (2) The development of the MFS reflects the continuation of tectonic rotations. (3) Three secondary faults (Awatere, Clarence, and Hope) may have developed within a short period of one another. This suggests that the change in plate motion has impacted in Marlborough. (4) Uplift movements of the Spenser Mountains and Kaikoura Ranges still continue. (5) Suggate’s model (1979) of a pre-existing fault offset of the Alpine Fault is not a unique result in the FE modelling. The extremely young fission track ages (<10 Ma) in the vicinity of the Alpine Fault bend and Seaward Kaikoura Range coincide with the recent rapid uplift/erosion in these areas. All the apatite ages are less than the corresponding depositional ages of the samples, which indicates that the host rocks in Marlborough have experienced exposure to elevated temperatures in the zone of partial annealing for apatite, some of them having been reset. Except for the samples in the Marlborough Sounds region, zircon fission track ages are older than 119 Ma, reflecting that the host rocks of the samples have not experienced temperatures in the zircon partial annealing zone since the mid Cretaceous. Apatite fission track ages and mean lengths indicate that there are two major cooling events: one occurring from the early Miocene (~20 Ma) and the other in the mid Cretaceous (~100 Ma). Modelled thermal histories indicate that in the Wairau block the timing of the main Neogene uplift/erosion event is earlier (mid to late Miocene) than to the southeast in the Seaward Kaikoura Range (late Pliocene-Pleistocene). The greatest amount of cooling in Marlborough occurs along the Alpine Fault in the vicinity of the big bend, where rocks have cooled from temperatures above 240 ± 25°C (temperature at which fission tracks are reset in zircon). These samples derive from the Alpine Schist belt. Over wide parts of Marlborough the rocks now at the surface have cooled from lower levels of the apatite partial annealing zone (<110°C). Generally, the rocks have cooled from at least 50°C to surface temperatures (10-15°C). The largest amount of rock uplift (~11.5 km) occurs in the area of the Alpine Fault bend. The amounts of rock uplift and denudation derived from the fission track parameters are in the range 0.7-11.5 km and 0.6-11.0 km, respectively. The amounts of rock uplift in the Inland and Seaward Kaikoura Ranges are about 2.4 and 4.8 km, respectively. The amount of denudation across Marlborough is generally higher in the Wairau block than elsewhere. In the Seaward Kaikoura Range, high elevation coincides with large amounts of denudation. Compared with the region of continent-continent convergence to the south in Canterbury, the amounts of rock uplift and denudation in Marlborough are relatively small, revealing the differences between a fully developed continent-continent collision zone and the continental transform setting in Marlborough. The horizontal movements determined by the FE modelling can be converted into vertical movements. Both the FE modelling and fission track results show that the pattern of vertical deformation is consistent with the topography in Marlborough: the younger the fission track age, the more uplift/deformation there has been. The FE modelling and fission track results reveal the character of the tectonic evolution of Marlborough and are a step towards its quantification

The Information Of The Milky Way From 2MASS Whole Sky Star Count: The Bimodal Color Distributions

The J-Ks color distribution (CD) with a bin size of 0.05 magnitude for the entire Milky Way has been carried out by using the Two Micron All Sky Survey Point Source Catalog (2MASS PSC). The CDs are bimodal, which has a red peak at 0.8 < J-Ks < 0.85 and a blue peak at 0.3 < J-Ks < 0.4. The colors of the red peak are more or less the same for the whole sky, but that of the blue peak depend on Galactic latitude, (J-Ks ~ 0.35 at low Galactic latitudes and 0.35 < J-Ks < 0.4 for other sky areas). The blue peak dominates the bimodal CDs at low Galactic latitudes and becomes comparable with the red peak in other sky regions. In order to explain the bimodal distribution and the global trend shown by the all sky 2MASS CDs, we assemble an empirical HR diagram, which is composed by observational-based near infrared HR diagrams and color magnitude diagrams, and incorporate a Milky Way model. In the empirical HR diagram, the main sequence stars turnoff the thin disk is relatively bluer, (J-Ks)0 = 0.31, when we compare with the thick disk which is (J-Ks)0 = 0.39. The age of the thin/thick disk is roughly estimated to be around 4-5/8-9 Gyr according to the color-age relation of the main sequence turnoff. In general, the 2MASS CDs can be treated as a tool to census the age of stellar population of the Milky Way in a statistical manner and to our knowledge this is a first attempt to measure the age.Comment: Accepted by ApJ on Sept. 11 201

Pulsed laser deposition of hexagonal GaN-on-Si(100) template for MOCVD applications

Growth of hexagonal GaN on Si(100) templates via pulsed laser deposition (PLD) was investigated for the further development of GaN-on-Si technology. The evolution of the GaN growth mechanism at various growth times was monitored by SEM and TEM, which indicated that the GaN growth mode changes gradually from island growth to layer growth as the growth time increases up to 2 hours. Moreover, the high-temperature operation (1000°C) of the PLD meant no significant GaN meltback occurred on the GaN template surface. The completed GaN templates were subjected to MOCVD treatment to regrow a GaN layer. The results of X-ray diffraction analysis and photoluminescence measurements show not only the reliability of the GaN template, but also the promise of the PLD technique for the development of GaN-on-Si technology

An in situ study on the coalescence of monolayer-protected Au-Ag nanoparticle deposits upon heating

The structural evolution of thiolate-protected nanoparticles of gold, silver, and their alloys with various Au/Ag ratios (3:1, 1:1, and 1:3) upon heating was investigated by means of in situ synchrotron radiation X-ray diffraction. The relationships between the coalescence and composition of nanoparticles, as well as the surfactant reactions, were clarified. Experimental results show that there existed a critical temperature ranging from 120°C to 164°C, above which the tiny broad X-ray diffraction peaks became sharp and strong due to particle coalescence. The coalescence temperatures for alloy nanoparticle deposits were clearly lower than those for pure metals, which can be ascribed to the rivalry between the thermodynamic effect due to alloying and the interactions between surface-assembled layers and the surface atoms of the nanoparticles. The strong affinity of thiolates to Ag and thus complex interactions give rise to a greater energy barrier for the coalescence of nanoparticles into the bulk and subsequent high coalescence temperature. The influences of particle coalescence on the optical and electrical properties of the nanoparticle deposits were also explored

Well-differentiated gall bladder hepatoid carcinoma producing alpha-fetoprotein: a case report

<p>Abstract</p> <p>Introduction</p> <p>Gall bladder carcinoma is rare, and metastatic gall bladder carcinoma from hepatocellular carcinoma has been reported in only a few patients.</p> <p>Case presentation</p> <p>We present a 73-year-old man with a history of hepatitis B virus-related liver cirrhosis and hepatocellular carcinoma. He received transcatheter arterial chemoembolization, and was diagnosed to have an alpha-fetoprotein producing gall bladder tumor with intraluminal growth. Open cholecystectomy was performed. Pathologic examination of the lesion revealed a well-differentiated hepatoid carcinoma. The lesion was thought most likely to be a metastatic lesion from previous hepatocellular carcinoma. His alpha-fetoprotein level dropped to normal levels five months after the surgery.</p> <p>Conclusion</p> <p>This unusual intraluminal growing tumor proved to be a well-differentiated hepatoid carcinoma, most likely a metastatic lesion from previous hepatocellular carcinoma. This case reminds clinicians that in looking for likely hepatocellular carcinoma recurrence, when no detectable hepatic lesion can account for an elevated alpha-fetoprotein level, the gall bladder should be included in the search for the site of metastasis.</p