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Tuberculosis has reemerged as a serious threat to human health because of the increasing prevalence of drug-resistant strains and synergetic infection with HIV, prompting an urgent need for new and more efficient treatments. The PhoP-PhoR two-component system of Mycobacterium tuberculosis plays an important role in the virulence of the pathogen and thus represents a potential drug target. To study the mechanism of gene transcription regulation by response regulator PhoP, we identified a high-affinity DNA sequence for PhoP binding using systematic evolution of ligands by exponential enrichment. The sequence contains a direct repeat of two 7 bp motifs separated by a 4 bp spacer, TCACAGC(N4)TCACAGC. The specificity of the direct-repeat sequence for PhoP binding was confirmed by isothermal titration calorimetry and electrophoretic mobility shift assays. PhoP binds to the direct repeat as a dimer in a highly cooperative manner. We found many genes previously identified to be regulated by PhoP that contain the direct-repeat motif in their promoter sequences. Synthetic DNA fragments at the putative promoter-binding sites bind PhoP with variable affinity, which is related to the number of mismatches in the 7 bp motifs, the positions of the mismatches, and the spacer and flanking sequences. Phosphorylation of PhoP increases the affinity but does not change the specificity of DNA binding. Overall, our results confirm the direct-repeat sequence as the consensus motif for PhoP binding and thus pave the way for identification of PhoP directly regulated genes in different mycobacterial genomes. [ABSTRACT FROM AUTHOR]

The bulge test has been utilized extensively in determining the mechanical properties of thin film materials. We develop a bulge-test system that consists of three main components, including an optical system, a loading system, and a control system. A telecentric lens is adopted as an imaging camera in an optical system to provide high imaging quality along with a constant angle of view across the entire field of view. The out-of-plane deformation is obtained by projecting a sinusoidal fringe pattern onto a specimen surface and analyzing recorded images with a digital image correlation algorithm. A least-squares polynomial fitting is presented to solve the problem that the out-of-plane calibration coefficient is not a constant. Experiments were performed to validate the availability and reliability of this proposed bulge-test system in the measurement of a dynamic microscopic deformation of membrane. The measuring range of deformation is from several microns to hundreds of microns with an accuracy of 0.6 µm. [ABSTRACT FROM AUTHOR]

A marattialean trunk of Psaronius laowujiensis sp. nov. is described from the Upper Permian of the Xuanwei Formation, Panxian County, Guizhou Province, South China. The specimen most likely represents the lower part of the trunk, because the preserved thickness of the root mantel is somewhat larger than the diameter of the stem. Meristeles of the stem are arranged in approximately five tangential stelar cycles but not in radial files. Inner meristeles are in small number, ∼12-13, and loosely arranged. Leaf traces diverge helically and are organized in a 2/5 phyllotaxy. The leaf base vascular configuration consists of three strands that include a large U-shaped, centrifugal strand, a small centripetal strand, and an inverted ϙ-shaped internal strand. A vascular bundle sheath one or two cell layers thick surrounds each meristele. Within the centripetal concavity of each peripheral cauline bundle there are anchor-shaped sclerenchymatous strands. Ground tissue appears to consist of aerenchymatous parenchyma, in which secretory cavities are dispersed. Bound roots mostly possess seven to nine protoxylem poles. The vascular bundle sheath is one or two cell layers thick. The inner cortex consists of aerenchymatous parenchyma. A detailed comparison of the present specimen with known species of Psaronius from the Permian of South China is made. Our specimen is similar to Psaronius wangii in many aspects, but the two can be clearly distinguished by the structure of the ground tissue of the stem and the leaf base vascular configuration, which leads to the erection of a new species, P. laowujiensis, for this specimen. Certain important characters in species from the Permian of South China are discussed. The tree- or anchor-shaped sclerenchymatous configuration within the centripetal concavity of the peripheral cauline bundles is unique to species from the South China Permian. The permanent vascular bundle sheath surrounding the meristeles of the stem and the stele of the root is another remarkable feature of those species. The analogous tissue, termed "inner cortex" by certain authors, is also present in some Psaronius from the Euramerican and North China floras, but in those cases it is thinner walled and not as remarkable as the vascular bundle sheath in the species from South China. The leaf base vascular configuration of the species from the Permian in South China is more diverse than those from other places. [ABSTRACT FROM AUTHOR]

Three-dimensional digital image correlation (3D-DIC) is widely used in various measurement fields. Once a DIC setup is established, different parameters, such as lens focal length, pixel size, stereo angle, and working distance, are easy to know or measure; the range of the matching error is generally 0.01–0.02 pixels. It would be very convenient if the measurement error could be estimated based on the parameters above without performing the entire DIC calculation process. In this study, a numerical simulation was conducted to study the variation of the 3D reconstruction error with the stereo angle in different measurement areas. It was found that the error of the center point was closely related to the error of the full field. Therefore, using simple parameters to describe the 3D reconstruction error of the center point is of great significance for estimating the overall error of a DIC system. The general solution of the 3D reconstruction equation was simplified on the premise that high order terms of pixel coordinates could be omitted. The derived error estimation formulas had a simple form and described the 3D reconstruction error of the center point in three directions. Through a set of static experiments, the 3D reconstruction error of a planar object under different stereo angles (from 10° to 120°) was studied. The matching error was calculated by a 2D-DIC software and inserted into the proposed formulas to obtain the estimated error. The estimated error was compared with the results of a 3D-DIC software, and the effectiveness of the proposed method was verified. [ABSTRACT FROM AUTHOR]

In many standard mechanical tests and in all two-dimensional digital image correlation (2D-DIC) applications, the surfaces of specimens to be measured are planar. For the special case of planar surfaces, in this paper an efficient approach for stereo matching was proposed to further improve the computation efficiency of stereo-DIC. The proposed stereo matching method utilizes the characteristic of planar objects that the projection transformation functions between left and right images are the same for all matched subsets and can be expressed by eight parameters. In each pair of images, four discrete points were matched to calculate the projection transformation matrix, and then the stereo matching of all other points could be accomplished based on the calculated projection transformation matrix in an easy and efficient way. Both simulations and experimental results demonstrated that the proposed method is feasible and effective and the computational speed is about 20 times faster than that of traditional method. Based on the proposed method, real-time stereo-DIC with a higher frame rate and more points should be achieved. [ABSTRACT FROM AUTHOR]

The development of stereo-digital image correlation (stereo-DIC) enables the application of vision-based technique that uses digital cameras to the deformation measurement of materials and structures. Compared with traditional contact measurements, the stereo-DIC technique allows for non-contact measurement, has a non-intrusive characteristic, and can obtain full-field deformation information. In this paper, a speckle-based calibration method is developed to calibrate the stereo-DIC system when the system is applied for deformation measurement of large engineering components. By combining speckle analysis with the classical relative orientation algorithm, relative rotation and translation between cameras can be calibrated based on analysis of experimental speckle images. For validation, the strain fields of a four-point bending beam and an axially loaded concrete column were determined by the proposed calibration method and stereovision measurement. As a practical application, the proposed calibration method was applied for strain measurement of a ductile iron cylindrical vessel in the drop test. The measured results verify that the proposed calibration method is effective for deformation measurement of large engineering components. [ABSTRACT FROM AUTHOR]

At present, the accuracy of strain measurement using a common optical extensometer with 2D digital image correlation is not sufficient for experimental applications due to the effect of out-of-plane motion. Therefore, this paper proposes a dual-reflector imaging method to improve the accuracy of strain measurement when using a common optical extensometer, with which the front and rear surfaces of a specimen can be simultaneously recorded in the sensor plane of a digital camera. By averaging the strain in two optical extensometers formed on the front and rear surfaces of a specimen, the effect of any slight out-of-plane motion can be eliminated and therefore the strain measurement accuracy can also be improved. Uniaxial tensile tests with an Al-alloy specimen, including static loading and continuous loading, were conducted to validate the feasibility and reliability of the proposed method. The strain measurement results obtained with the proposed method and those obtained with an electrical-resistance strain gauge were found to be in good agreement. The average errors of the proposed method for the two continuous loading tests were found to be 8  ±  10 με and  −6  ±  8 με. Given that no correction sheet or compensation specimen is required, the proposed method is easy to implement and thus especially suitable for determining the mechanical properties of brittle materials due to the high level of accuracy with which strain can be measured. [ABSTRACT FROM AUTHOR]

A simple and repeatable speckle creation method based on water transfer printing (WTP) is proposed to reduce artificial measurement error for digital image correlation (DIC). This technique requires water, brush, and a piece of transfer paper that is made of prefabricated decal paper, a protected sheet, and printed speckle patterns. The speckle patterns are generated and optimized via computer simulations, and then printed on the decal paper. During the experiments, operators can moisten the basement with water and the brush, so that digital patterns can be simply transferred to the carriers’ surfaces. Tensile experiments with an extended three-dimensional (3D) DIC system are performed to test and verify the validity of WTP patterns. It is shown that by comparing with a strain gage, the strain error is less than 50με in a uniform tensile test. From five carbon steel tensile experiments, Lüders bands in both WTP patterns and spray paint patterns are demonstrated to propagate symmetrically. In the necking part where the strain is up to 66%, WTP patterns are proved to adhere to the specimens well. Hence, WTP patterns are capable of maintaining coherence and adherence to the specimen surface. The transfer paper, working as the role of strain gage in the electrometric method, will contribute to speckle creation. [ABSTRACT FROM AUTHOR]

Saccharomyces cerevisiae Pta1 is a component of the cleavage/polyadenylation factor (CPF) 3′-end processing complex and functions in pre-mRNA cleavage, poly(A) addition, and transcription termination. In this study, we investigated the role of the N-terminal region of Pta1 in transcription and processing. We report that a deletion of the first 75 amino acids (pta1-Δ75) causes thermosensitive growth, while the deletion of an additional 25 amino acids is lethal. The pta1-Δ75 mutant is defective for snoRNA termination, RNA polymerase II C-terminal domain Ser5-P dephosphorylation, and gene looping but is fully functional for mRNA 3′-end processing. Furthermore, different regions of Pta1 interact with the CPF subunits Ssu72, Pti1, and Ysh1, supporting the idea that Pta1 acts as a scaffold to organize CPF. The first 300 amino acids of Pta1 are sufficient for interactions with Ssu72, which is needed for pre-mRNA cleavage. By the degron-mediated depletion of Pta1, we show that the removal of this essential region leads to a loss of Ssu72, yet surprisingly, in vitro cleavage and polyadenylation remain efficient. In addition, a fragment containing amino acids 1 to 300 suppresses 3′-end processing in wild-type extracts. These findings suggest that the amino terminus of Pta1 has an inhibitory effect and that this effect can be neutralized through the interaction with Ssu72. [ABSTRACT FROM AUTHOR]

In order to have an efficient design methodology and achieve high-performance inertial instruments, it is important to analyze the dynamic characteristics of micromechanical vibratory gyroscopes. In this paper, a novel optical method based on a high-speed CMOS camera and digital image spectrum correlation is developed to measure the motion of the sensitive elements. Unlike digital image correlation (DIC) in the spatial domain, correlation in the spectral domain gives direct access to the whole image under translational motion, which retains all the advantages of DIC and provides an expanded range of measurement. In addition, the proposed method is much faster in computation and capable of calculating dynamic temporal serial images in real time. The proposed method is employed to obtain the displacement of temporal series images and to extract dynamical parameters such as resonant frequency and quality factor at atmospheric pressure. During dynamic testing, the discrete wavelet transform is employed to eliminate the low-frequency components, and the continuous wavelet transform (CWT) for identification of the frequency and damping ratio. Experimental results show that the proposed method is a direct inspection tool and a practical alternative to the conventional electrical measurements of micromechanical vibratory gyroscopes. [ABSTRACT FROM AUTHOR]

A 60-nucleotide region (S1) downstream of the transcription start site of the cauliflower mosaic virus 35S RNA can enhance gene expression. By using transient expression assays with plant protoplasts, this activity was shown to be at least partially due to the effect of transcriptional enhancers within this region. We identify sequence motifs with enhancer function, which are normally masked by the powerful upstream enhancers of the 35S promoter. A repeated CT-rich motif is involved both in enhancer function and in interaction with plant nuclear proteins. The S1 region can also enhance expression from heterologous promoters. [ABSTRACT FROM AUTHOR]