Sediment trapping in deltas of small mountainous rivers of southwestern Taiwan and its influence on East China Sea sedimentation

Taiwan's setting of high mountains, steep gradients, frequent earthquakes, erodible lithology, and heavy rainfall represents an ideal site to focus on sedimentary processes of the deltas of small mountainous rivers (SMRs). Several SMRs in southwestern Taiwan have deposited a thick sedimentary succession in the composite Southwest Taiwan Delta (SWTD) since the middle Holocene. Evidence from the SWTD can help to determine its trapping efficiency and assess the role of SMRs in sediment transport to the sea. We used historical nautical charts, bathymetric data, satellite radar data, and 14C dates to calculate the sediment volume of the SWTD on millennial and decadal scales. The 14C dates of core samples indicate deposition of thick deltaic sediment in subsiding areas since the time of the maximum flooding surface about 7 cal ka BP. The paleo-shoreline changes of the SWTD suggest a steady westward progradation since 7 cal ka BP. In contrast, the nautical charts suggest minor volume reduction of the offshore part of the SWTD, with a deepening trend and retreating shorelines, during the last seven decades. The results show that at least 201.72 ± 13.90 km3 (~3.23 105 Mt) of sediment has been trapped in the SWTD since 7 cal ka BP, and that the delta has shifted to a destructive phase during the past seven decades as human influences such as construction of reservoirs, dams, and weirs in the hills have reduced the sediment supply. The birth of the Taiwan Warm Current and following continuous sediment supply from the western rivers of Taiwan to the East China Sea since ~7.3 cal ka BP have played a crucial role in the sedimentation of the East China Sea, particularly in the Okinawa Trough, and the Japan Sea through the Tsushima Warm Current

Strain and field modulation in bilayer graphene band structure

Using an external electric field, one can modulate the bandgap of Bernal stacked bilayer graphene by breaking A-~B symmetry. We analyze strain effects on the bilayer graphene using the extended Huckel theory and find that reduced interlayer distance results in higher bandgap modulation, as expected. Furthermore, above about 2.5 angstrom interlayer distance, the bandgap is direct, follows a convex relation to electric field and saturates to a value determined by the interlayer distance. However, below about 2.5 angstrom, the bandgap is indirect, the trend becomes concave and a threshold electric field is observed, which also depends on the stacking distance.Comment: 3 pages, 5 figures - v1 and v2 are the same, uploaded twice - v3, some typos fixed and a reference adde

Optimization temperature sensitivity using the optically detected magnetic resonance spectrum of a nitrogen-vacancy center ensemble

Temperature sensing with nitrogen vacancy (NV) centers using quantum techniques is very promising and further development is expected. Recently, the optically detected magnetic resonance (ODMR) spectrum of a high-density ensemble of the NV centers was reproduced with noise parameters [inhomogeneous magnetic field, inhomogeneous strain (electric field) distribution, and homogeneous broadening] of the NV center ensemble. In this study, we use ODMR to estimate the noise parameters of the NV centers in several diamonds. These parameters strongly depend on the spin concentration. This knowledge is then applied to theoretically predict the temperature sensitivity. Using the diffraction-limited volume of 0.1 micron^3, which is the typical limit in confocal microscopy, the optimal sensitivity is estimated to be around 0.76 mK/Hz^(1/2) with an NV center concentration of 5.0e10^17/cm^3. This sensitivity is much higher than previously reported sensitivities, demonstrating the excellent potential of temperature sensing with NV centers.Comment: 17 pages, 4 figures, 1 tabl

Fibronectin-β1 Integrin Interaction in Teeth

The dental epithelium and extracellular matrix interact to ensure that cell growth and differentiation lead to the formation of teeth of appropriate size and quality. To determine the role of fibronectin in differentiation of the dental epithelium and tooth formation, we analyzed its expression in developing incisors. Fibronectin mRNA was expressed during the presecretory stage in developing dental epithelium, decreased in the secretory and early maturation stages, and then reappeared during the late maturation stage. The binding of dental epithelial cells derived from postnatal day-1 molars to a fibronectin-coated dish was inhibited by the RGD but not RAD peptide, and by a β1 integrin-neutralizing antibody, suggesting that fibronectin-β1 integrin interactions contribute to dental epithelial-cell binding. Because fibronectin and β1 integrin are highly expressed in the dental mesenchyme, it is difficult to determine precisely how their interactions influence dental epithelial differentiation in vivo. Therefore, we analyzed β1 integrin conditional knockout mice (Intβ1lox-/lox-/K14-Cre) and found that they exhibited partial enamel hypoplasia, and delayed eruption of molars and differentiation of ameloblasts, but not of odontoblasts. Furthermore, a cyst-like structure was observed during late ameloblast maturation. Dental epithelial cells from knockout mice did not bind to fibronectin, and induction of ameloblastin expression in these cells by neurotrophic factor-4 was inhibited by treatment with RGD peptide or a fibronectin siRNA, suggesting that the epithelial interaction between fibronectin and β1 integrin is important for ameloblast differentiation and enamel formation

Armchair graphene nanoribbons: Electronic structure and electric field modulation

We report electronic structure and electric field modulation calculations in the width direction for armchair graphene nanoribbons (acGNRs) using a semi-empirical extended Huckel theory. Important band structure parameters are computed, e.g. effectives masses, velocities and bandgaps. For the three types of acGNRs, the pz orbital tight-binding parameters are extracted if feasible. Furthermore, the effect of electric field in the width direction on acGNRs dispersion is explored. It is shown that for the two types of semiconducting acGNRs, an external electric field can reduce the bandgap to a few meV with different quantitative behavior.Comment: 5 pages, 5 figure

An Extended Huckel Theory based Atomistic Model for Graphene Nanoelectronics

An atomistic model based on the spin-restricted extended Huckel theory (EHT) is presented for simulating electronic structure and I-V characteristics of graphene devices. The model is applied to zigzag and armchair graphene nano-ribbons (GNR) with and without hydrogen passivation, as well as for bilayer graphene. Further calculations are presented for electric fields in the nano-ribbon width direction and in the bilayer direction to show electronic structure modification. Finally, the EHT Hamiltonian and NEGF (Nonequilibrium Green's function) formalism are used for a paramagnetic zigzag GNR to show 2e2/h quantum conductance.Comment: 5 pages, 8 figure

Identification and characterization of DUSP27, a novel dual-specific protein phosphatase

AbstractA novel human dual-specific protein phosphatase (DSP), designated DUSP27, is here described. The DUSP27 gene contains three exons, rather than the predicted 4–14 exons, and encodes a 220 amino acid protein. DUSP27 is structurally similar to other small DSPs, like VHR and DUSP13. The location of DUSP27 on chromosome 10q22, 50kb upstream of DUSP13, suggests that these two genes arose by gene duplication. DUSP27 is an active enzyme, and its kinetic parameters and were determined. DUSP27 is a cytosolic enzyme, expressed in skeletal muscle, liver and adipose tissue, suggesting its possible role in energy metabolism

miR-1 and Tooth Development

Many genes encoding growth factors, receptors, and transcription factors are induced by the epithelial-mesenchymal interaction during tooth development. Recently, numerous functions of microRNAs (miRNAs) are reportedly involved in organogenesis and disease. miRNAs regulate gene expression by inhibiting translation and destabilizing mRNAs. However, the expression and function of miRNAs in tooth development remain poorly understood. This study aimed to analyze the expression of miRNAs produced during tooth development using a microarray system to clarify the role of miRNAs in dental development. miR-1 showed a unique expression pattern in the developing tooth. miR-1 expression in the tooth germ peaked on embryonic day 16.5, decreasing gradually on postnatal days 1 and 3. An in situ hybridization assay revealed that miR-1 is expressed at the cervical loop of the dental epithelium. The expression of miR-1 and connexin (Cx) 43, a target of miR-1, were inversely correlated both in vitro and in vivo. Knockdown of miR-1 induced the expression of Cx43 in dental epithelial cells. Interestingly, cells with miR-1 downregulation proliferated slower than the control cells. Immunocytochemistry revealed that Cx43 in cells with miR-1 knockdown formed both cell-cell gap junctions and hemichannels at the plasma membrane. Furthermore, the rate of ATP release was higher in cells with miR-1 knockdown than in control cells. Furthermore, Cx43 downregulation in developing molars was observed in Epiprofin-knockout mice, along with the induction of miR-1 expression. These results suggest that the expression pattern of Cx43 is modulated by miR-1 to control cell proliferation activity during dental epithelial cell differentiation

Structural basis for translation termination by archaeal RF1 and GTP-bound EF1 complex

ABSTRACT When a stop codon appears at the ribosomal A site, the class I and II release factors (RFs) terminate translation. In eukaryotes and archaea, the class I and II RFs form a heterodimeric complex, and complete the overall translation termination process in a GTP-dependent manner. However, the structural mechanism of the translation termination by the class I and II RF complex remains unresolved. In archaea, archaeal elongation factor 1 alpha (aEF1a), a carrier GTPase for tRNA, acts as a class II RF by forming a heterodimeric complex with archaeal RF1 (aRF1). We report the crystal structure of the aRF1 · aEF1a complex, the first active class I and II RF complex. This structure remarkably resembles the tRNA · EF-Tu complex, suggesting that aRF1 is efficiently delivered to the ribosomal A site, by mimicking tRNA. It provides insights into the mechanism that couples GTP hydrolysis by the class II RF to stop codon recognition and peptidyltRNA hydrolysis by the class I RF. We discuss the different mechanisms by which aEF1a recognizes aRF1 and aPelota, another aRF1-related protein and molecular evolution of the three functions of aEF1a

Molecular contribution to cleft palate production in cleft lip mice

Cleft palate following cleft lip may include a developmental disorder during palatogenesis. CL/Fr mice fetuses, which develop cleft lip and palate spontaneously, have less capability for in vivo cell proliferation in palatal mesenchyme compared with CL/Fr normal fetuses. In order to know the changes of signaling molecules contributing to cleft palate morphogenesis following cleft lip, the mRNA expression profiles were compared in palatal shelves oriented vertically (before elevation) in CL/Fr fetuses with or without cleft lip. The changes in mRNA profile of cleft palate morphogenesis were presented in a microarray analysis, and genes were restricted to lists contributing to cleft palate development in CL/Fr fetuses with cleft lip. Four candidate genes (Ywhab, Nek2, Tacc1 and Frk) were linked in a gene network that associates with cell proliferation (cell cycle, MAPK, Wnt and Tgf beta pathways). Quantitative real-time RT-PCR highlighted the candidate genes that significantly changed in CL/Fr fetuses with cleft lip (Ywhab, Nek2 and Tacc1). The results of these molecular contributions will provide useful information for a better understanding of palatogenesis in cleft palate following cleft lip. Our data indicated the genetic contribution to cleft palate morphogenesis following cleft lip