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Although activating mutations in RAS oncogenes are known to result in aberrant signaling through multiple pathways, the role of microRNAs (miRNAs) in the Ras oncogenic program remains poorly characterized. Here we demonstrate that Ras activation leads to repression of the miR-143/145 cluster in cells of human, murine, and zebrafish origin. Loss of miR-143/145 expression is observed frequently in KRAS mutant pancreatic cancers, and restoration of these miRNAs abrogates tumorigenesis. miR-143/145 down-regulation requires the Ras-responsive element-binding protein (RREB1), which represses the miR-143/145 promoter. Additionally, KRAS and RREB1 are targets of miR-143/miR-145, revealing a feed-forward mechanism that potentiates Ras signaling.

We report on the fabrication of ZnO-channel charge injection memory thin-film transistors (TFTs). Our non-volatile memory TFT has a thin pentacene on top of a dielectric sandwich which has 3 nm-thin inserted potential well as a hole trap layer. The thin pentacene in contact with Au top electrode supports effective hole injection from pentacene into the inserted well under +8 V programming gate pulse while those injected holes are effectively ejected out under −8 V pulse, so that ZnO channel below the dielectric may have two different current states: write and erase. Our device operates at less than 2 V and shows a retention time of about 1000 s after programmed at +8 V, along with an effective program/erase ratio of 5–20.

Transparent electronics has been one of the key terminologies forecasting the ubiquitous technology era. Several researchers have thus extensively developed transparent oxide-based thin-film transistors (TFTs) on glass and plastic substrates. However, work in transparent electronics has been limited mostly to high-voltage devices operating at more than a few tens of volts, and has mainly focused on transparent display drivers. Low-voltage logic devices, such as transparent complementary inverters, operating in an electrically stable and photo-stable manner, are now very necessary to practically realize transparent electronics. Electrically stable dielectrics with high strength and high capacitance must also be proposed to support this mission, and simultaneously these dielectrics must be compatible with both n- and p-channel TFTs in device fabrication. Here, a nanohybrid dielectric layer that is composed of multiple units of inorganic oxide and organic self-assembled monolayer is proposel to support a transparent complementary TFT inverter operating at 3 V.

We report on the fabrication of pentacene-based thin-film transistors (TFTs) with a 230 nm-thick double polymer dielectric composed of 30 nm-thin low- k poly-4-vinyphenol (PVP) and 200 nm-thick high- k poly(vinylidene fluoride/trifluoroethylene) [P(VDF–TrFE)] dielectric on polyethersulfone (PES) films. Our 230 nm-thick double (high- k /low- k ) polymer showed a good dielectric strength of ∼2 MV/cm, a high capacitance of 26 nF/cm 2 with k = ∼7. Based on this double polymer dielectric, our flexible pentacene TFT displayed a high saturation mobility of 1.22 cm 2 /V s, a threshold voltage of −2.5 V, and on/off ratio of 10 3 , stably operating under −5 V.

We report a low-temperature fabrication of mixed-organic–inorganic nanohybrid superlattices for high-k thin stable gate dielectrics on flexible substrates. The self-assembled organic layers (SAOLs) were grown by repeated sequential adsorptions of C C-terminated alkylsilane and metal (Al or Ti) hydroxyl with ozone activation, which was called “molecular layer deposition (MLD)”. The MLD method is a self-controlled layer-by-layer growth process under vacuum conditions, and is perfectly compatible with the atomic layer deposition (ALD) method. The TiO2 and Al2O3 inorganic layers were grown by ALD, which relies on sequential saturated surface reactions resulting in the formation of a monolayer in each sequence and is a potentially powerful method for preparing high quality multicomponent superlattices. The MLD method combined with ALD (MLD–ALD) was applied to fabricate SAOLs-Al2O3–SAOLs-TiO2 nanohybrid superlattices on polycarbonate substrates with accurate control of film thickness, large-scale uniformity, excellent conformality, good reproducibility, multilayer processing capability, sharp interfaces, and excellent film qualities at relatively low temperature. The prepared ultrathin nanohybrid films exhibited good thermal and mechanical stability, good flexibility, excellent insulating properties, and relatively high dielectric constant k (6–11). The MLD–ALD method is an ideal fabrication technique for various flexible electronic devices.

In this article a new approach for solving the Reactive Hoist Scheduling Problem is proposed. The investigation focuses on the case where multiple hoists, sharing the same rail, are used to convey a single type of jobs along the line according to a given production sequence. It is based on two distinct, though coupled, multi-agent systems. The first system is responsible for making a decision about the input date for the next job, while the second system is concerned with the assignment of transfer operations of jobs between tanks to the hoists. These multi-agent systems use two different types of auction mechanisms to attain cooperation.

In this paper, the conventional k-modes-type algorithms for clustering categorical data are extended by representing the clusters of categorical data with k-populations instead of the hard-type centroids used in the conventional algorithms. Use of a population-based centroid representation makes it possible to preserve the uncertainty inherent in data sets as long as possible before actual decisions are made. The k-populations algorithm was found to give markedly better clustering results through various experiments.

In this paper the conventional subtractive clustering method is extended by calculating the mountain value of each data point based on a kernel-induced distance instead of the conventional sum-of-squares distance. The kernel function is a generalization of the distance metric that measures the distance between two data points as the data points are mapped into a high dimensional space. Use of the kernel function makes it possible to cluster data that is linearly non-separable in the original space into homogeneous groups in the transformed high dimensional space. Application of the conventional subtractive method and the kernel-based subtractive method to well-known data sets showed the superiority of the proposed approach.

By using a kernel function, data that are not easily separable in the original space can be clustered into homogeneous groups in the implicitly transformed high-dimensional feature space. Kernel k-means algorithms have recently been shown to perform better than conventional k-means algorithms in unsupervised classification. However, few reports have examined the benefits of using a kernel function and the relative merits of the various kernel clustering algorithms with regard to the data distribution. In this study, we reformulated four representative clustering algorithms based on a kernel function and evaluated their performances for various data sets. The results indicate that each kernel clustering algorithm gives markedly better performance than its conventional counterpart for almost all data sets. Of the kernel clustering algorithms studied in the present work, the kernel average linkage algorithm gives the most accurate clustering results.

Motivation: Clustering has been used as a popular technique for finding groups of genes that show similar expression patterns under multiple experimental conditions. Many clustering methods have been proposed for clustering gene-expression data, including the hierarchical clustering, k-means clustering and self-organizing map (SOM). However, the conventional methods are limited to identify different shapes of clusters because they use a fixed distance norm when calculating the distance between genes. The fixed distance norm imposes a fixed geometrical shape on the clusters regardless of the actual data distribution. Thus, different distance norms are required for handling the different shapes of clusters. Results: We present the Gustafson--Kessel (GK) clustering method for microarray gene-expression data. To detect clusters of different shapes in a dataset, we use an adaptive distance norm that is calculated by a fuzzy covariance matrix (F) of each cluster in which the eigenstructure of F is used as an indicator of the shape of the cluster. Moreover, the GK method is less prone to falling into local minima than the k-means and SOM because it makes decisions through the use of membership degrees of a gene to clusters. The algorithmic procedure is accomplished by the alternating optimization technique, which iteratively improves a sequence of sets of clusters until no further improvement is possible. To test the performance of the GK method, we applied the GK method and well-known conventional methods to three recently published yeast datasets, and compared the performance of each method using the Saccharomyces Genome Database annotations. The clustering results of the GK method are more significantly relevant to the biological annotations than those of the other methods, demonstrating its effectiveness and potential for clustering gene-expression data. Availability: The software was developed using Java language, and can be executed on the platforms that JVM (Java Virtual Machine) is running. It is available from the authors upon request. Contact: dhlee@bisl.kaist.ac.kr Supplementary information: Supplementary data are available at http://dragon.kaist.ac.kr/gk

A new cluster validity index is proposed that determines the optimal partition and optimal number of clusters for fuzzy partitions obtained from the fuzzy c-means algorithm. The proposed validity index exploits an overlap measure and a separation measure between clusters. The overlap measure, which indicates the degree of overlap between fuzzy clusters, is obtained by computing an inter-cluster overlap. The separation measure, which indicates the isolation distance between fuzzy clusters, is obtained by computing a distance between fuzzy clusters. A good fuzzy partition is expected to have a low degree of overlap and a larger separation distance. Testing of the proposed index and nine previously formulated indexes on well-known data sets showed the superior effectiveness and reliability of the proposed index in comparison to other indexes.

In this paper the conventional fuzzy k-modes algorithm for clustering categorical data is extended by representing the clusters of categorical data with fuzzy centroids instead of the hard-type centroids used in the original algorithm. Use of fuzzy centroids makes it possible to fully exploit the power of fuzzy sets in representing the uncertainly in the classification of categorical data. To test the proposed approach, the proposed algorithm and two conventional algorithms (the k-modes and fuzzy k-modes algorithms) were used to cluster three categorical data sets. The proposed method was found to give markedly better clustering results.

A new cluster validity index is proposed for fuzzy partitions obtained from Fuzzy C-Means algorithm. The proposed validity index exploits an inter-cluster proximity between fuzzy clusters. The inter-cluster proximity is used to measure the degree of overlap between clusters. A low proximity value indicates well-partitioned clusters. The best fuzzy c-partition is obtained by minimizing the inter-cluster proximity with respect to c. Well-known data sets are tested to show the effectiveness and reliability of the proposed index.

Static and dynamic fracture of interfaces between orthotropic and isotropic materials were studied using photoelasticity. In this study, a bi-material specimen made of PSM-1 ® and Scotchply ® 1002, a unidirectional glass fiber reinforced epoxy composite, was used. Two fiber orientations, fibers parallel to the interface ( α =0°) and fibers perpendicular to the interface ( α =90°) were considered. Center crack bi-material specimens having different crack lengths were loaded quasi-statically and the full-field isochromatics were recorded using a digital camera. The complex stress intensity factor corresponding to each crack length was calculated from the isochromatics and the values were compared to that obtained from boundary collocation method. Dynamic interfacial fracture was studied with an edge crack bi-material geometry for the two different fiber orientations. The isochromatics around the propagating crack were recorded using a digital high-speed camera. The fracture parameters such as crack speed, complex stress intensity factor and energy release rate were extracted from the isochromatics using the asymptotic stress field equations. The complex stress intensity factor obtained from the static experiments was in close agreement with that calculated using the boundary collocation method. The results also indicated that the fiber orientation with respect to the interface influences the fracture parameters for stationary and propagating cracks.

We report on the fabrication of a transparent photostable cell circuit composed of drive and resistor diodes which are face-to-face connected to each other with different device area. The diodes consisted of e-beam evaporated p-NiO on sputter-deposited n-ZnO for p/n diode formation on indium-tin-oxide glass. Our transparent diodes show photostable rectifying behavior, about 103 on/off current ratio and even dynamic rectification at a maximum frequency of 100 Hz AC input signal in ambient light. The noticeable photo-responsivity of the circuit was obtained only under ultraviolet (UV) light. We conclude that our transparent diode circuit is promising in enriching the field of transparent device electronics. (© 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

We propose new support vector machines (SVMs) that incorporate the geometric distribution of an input data set by associating each data point with a possibilistic membership, which measures the relative strength of the self class membership. By using a possibilistic distance measure based on the possibilistic membership, we reformulate conventional SVMs in three ways. The proposed methods are shown to have better classification performance than conventional SVMs in various tests.

We have examined the mechanisms by which tumor cells bind to endothelial cells utilizing cultured melanoma cells and microvascular endothelial cells derived from human dermis (HDMEC). The ability of biologic response modifiers (BRM) to modulate the adhesion of melanoma cells to HDMEC was defined and those results were compared with results from human umbilical vein endothelial cells (HUVEC). SK-MEL-2, WM266-4, and Hs 294T melanoma cells all bound to HDMEC and HUVEC monolayers and adherence of melanoma cells was enhanced in a dose- and time-dependent manner by the treatment of HDMEC with interleukin 1 (IL-1) alpha or tumor necrosis factor (TNF) alpha. Similar increases in binding to HDMEC or HUVEC were induced after BRM stimulation, although baseline melanoma cell binding to HUVEC tended to be slightly higher than to HDMEC. In contrast, whereas phorbol 12-myristate 13-acetate (PMA) augmented melanoma cell adherence to HDMEC, PMA failed to increase adherence to HUVEC. The alterations in melanoma cell binding were induced only after pretreatment of endothelial and not melanoma cells with PMA. Studies of the expression of cell adhesion molecules (CAM) on HDMEC and HUVEC using enzyme-linked immunosorbent assay showed that vascular cell adhesion molecule 1 (VCAM-1) is not induced by PMA on HDMEC and intercellular adhesion molecule 1 (ICAM-1) is downregulated on HDMEC by PMA treatment. Endothelial leukocyte adhesion molecule 1 (ELAM-1) is induced by PMA, IL-1 alpha, or TNFalpha, but its expression does not correlate with increased melanoma cell binding MoAb recognizing VCAM-1-inhibited TNFalpha-induced increases in melanoma cell binding to HUVEC. However, anti-VCAM-1 antibody failed to clock melanoma cell binding to PMA or IL-1 alpha-stimulated HDMEC and only partially inhibited melanoma cell binding to TNF alpha-stimulated HDMEC. This study demonstrates that PMA and IL-1 alpha-induced increases in melanoma cell adherence to HDMEC are not mediated via known CAM, including ICAM-1, VCAM-1, or ELAM-1, and may be affected through microvessel-specific novel proteins not previously described on endothelial cells.

We report on photo-excited trap-charge-collection spectroscopy as a direct probe of the traps in organic field-effect transistors (OFETs). Monochromatic photon beams transmitted through the working channels of 5 V operating pentacene-OFETs with 60 nm thick Al2O3 dielectrics liberate interface charges trapped at the matched energy level while the oxide surfaces were prepared with various self-assembled monolayers (SAMs). The density of states (DOS) of traps is directly mapped as a function of the photon energy by tracking the change in the threshold voltage. While conventional electrical stability measurements qualitatively support our trap DOS spectroscopy results, our direct measurement technique provides a powerful tool for quantitative analysis of the nature and density of interfacial traps in field-effect transistor devices.

We report on the fabrication of ZnO nonvolatile memory thin-film transistors (NVM-TFTs) with thin poly(vinylidene fluoride/trifluoroethylene) [P(VDF-TrFE)] ferroelectric layer. Our NVM-TFT operates on glass substrates under low voltage write-erase (WR-ER) pulse of ±20 V with a maximum field effect mobility of ∼1 cm2/V s, maximum memory window of ∼20 V, and WR-ER current ratio of 4×102. When the NVM-TFT has a modified channel/ferroelectric interface with an inserted thin Al2O3 buffer layer, our device shows long retention time of more than 104 s, which is much enhanced compared to that of the other device without the buffer. The dynamic response of our devices with or without the buffer was clear enough to distinguish the WR and ER states as performed with 300 ms pulse.

We report that the optimum pentacene channel thickness is dependent on the surface energy state of its dielectric substrate. Pentacene thin-film transistor (TFT) with hydrophobic substrate displays a peak linear mobility at an optimum channel thickness of 50nm, below or above which the linear mobility decreases. In contrast, the linear mobility of the TFT with hydrophilic substrate monotonically increases until the channel thickness decreases to 15nm. According to atomic force microscopy of 15-nm-thin pentacene grown on the SiO2 and poly-4-vinyphenol (PVP) dielectrics, the pentacene islands on PVP are not perfectly interconnected unlike the case on SiO2.

We report on the fabrication of ZnO-based depletion-load-type inverter composed of two n-channel ZnO thin-film transistors (TFTs) with a low-k poly-4-vinylphenol and high-k poly(vinylidene fluoride-trifluoroethylene) double polymer dielectric. One of the two ZnO channels in the inverter was illuminated by 352 nm wavelength ultraviolet so that the illuminated ZnO channel might be depleted. That ZnO-TFT plays as a driver transistor in the inverter set where the original TFT is used as a load one. The both TFTs show the same mobility of ∼0.3 cm2/V s and our inverter operates with a voltage gain of ∼4 at low supplied voltages (5–7 V), demonstrating a dynamic response of ∼20 ms.

We report on the fabrication of top-gate ZnO thin-film transistors (TFTs) with organic and inorganic nanohybrid dielectric layers that take superlattice form in their inside structure. The nanohybrid dielectrics were prepared by the alternate deposition of organic self-assembled monolayer and oxide monolayer on sputter-deposited ZnO channel. With a 22-nm-thin AlOx-based hybrid dielectric layer (∼130nFcm2), our ZnO TFT showed a field mobility of 0.36cm2Vs operating at 8V, while the mobility increased up to 0.66cm2Vs with a 22-nm-thin AlOx-based/TiOx-based/AlOx-based (5.5nm11nm5.5nm and ∼220nFcm2) triple hybrid layer under 2V operation. Since both ZnO-TFTs display little gate hysteresis, we conclude that our nanohybrid dielectric approach is promising to achieve a gate-stable low voltage top-gate ZnO-TFTs.

The authors report on the fabrication of pentacene-based thin-film transistors (TFTs) with a 13nm-thick nanohybrid superlattice-type dielectric composed of ten units of molecular aluminum oxide (AlOx)-self-assembled multilayer (SAMu) lattice on indium-tin-oxide (ITO) glass or on n+-Si substrate. The AlOx-SAMu nanohybrid layers showed high dielectric capacitances of 187 and 233nF∕cm2 on ITO glass and on n+-Si substrate, respectively, along with a high dielectric strength of 4MV∕cm in both cases. Our pentacene-TFTs showed a maximum field effect mobility of 0.92cm2∕Vs, operating at −3V with an on/off current ratio of ∼103. Load-resistance inverter using our pentacene-TFT demonstrated a decent voltage gain of ∼5.