Holographic inspection of plates with regions of local thinning as defects

This paper describes the use of double-exposure holography on the detection and assessment of plates containing locally thinned regions as artificial defects. The artificial defect is programmed by thinning locally a plate to various depths with a milling cutter. During testing, the plate, illuminated by an expanded laser beam, is clamped along its periphery and an incremental uniform pressure applied between two exposures on the holographic plate. Local thinning is revealed from anomaly in the reconstructed fringe pattern—the boundary of the anomalous fringes is larger than the boundary of the actual artificial defect, and the amount of thinning is deduced from the number of fringes within the boundary. Artificial defects with eccentric local thinning are more readily revealed from the reconstructed fringe pattern than the artificial centric defects. A simple theoretical model is developed so that when the experimental fringe-counts are compared with the theoretical ones, any discrepancy between them reveals not only the presence of centric and eccentric artificial flaws but also their sizes and depths.     

Conceptual transaction modeling

Transaction modeling, which involves capturing the dynamic properties of an organization, is seen as a necessary component in data modeling. A specification language-transaction schema based on the ACM/PCM specification language-is implemented as the transaction modeling tool. The benefit of such a modeling tool is discussed and, in particular, illustrated by its capability to extend the static schema automatically in order to support the intended transactions     

A simplified in vivo drug sensitivity test for malaria in the field

Using a derivative of the plasmid pBR322 we have tested the dimer catastrophe hypothesis of plasmid instability. Most of the theory was confirmed by our observations, but our data suggest that some of the quantitative aspects need modification. In a recF strain of Escherichia coli we estimated the difference in loss rate between the plasmid in the monomeric and the dimeric state to be a factor of 13-14 and the difference in the loss rate between the plasmid in the monomeric and the trimeric state to be a factor of 14-50. We were able to confirm that plasmid oligomers were heterogeneously distributed within a rec+ population, but we were unable to detect any pronounced difference in the level of growth inhibition exerted by the plasmid when in the monomeric, dimeric, or trimeric state. This leaves open the question as to whether runaway plasmid multimerization was prevented (i) by a small correlation between the inhibition of growth and the 'multimeric status' of the plasmid, (ii) by intramolecular homologous recombination, or (iii) whether the process of runaway multimerization is too slow to be recognized within the duration of the experiments, i.e. 200 generations of growth.     

Treatment of irritable bowel syndrome with Chinese herbal medicine: a randomized controlled trial

CONTEXT: Irritable bowel syndrome (IBS) is a common functional bowel disorder for which there is no reliable medical treatment. OBJECTIVE: To determine whether Chinese herbal medicine (CHM) is of any benefit in the treatment of IBS. DESIGN: Randomized, double-blind, placebo-controlled trial conducted during 1996 through 1997. SETTING: Patients were recruited through 2 teaching hospitals and 5 private practices of gastroenterologists, and received CHM in 3 Chinese herbal clinics. PATIENTS: A total of 116 patients who fulfilled the Rome criteria, an established standard for diagnosis of IBS. INTERVENTION: Patients were randomly allocated to 1 of 3 treatment groups: individualized Chinese herbal formulations (n = 38), a standard Chinese herbal formulation (n = 43), or placebo (n = 35). Patients received 5 capsules 3 times daily for 16 weeks and were evaluated regularly by a traditional Chinese herbalist and by a gastroenterologist. Patients, gastroenterologists, and herbalists were all blinded to treatment group. MAIN OUTCOME MEASURES: Change in total bowel symptom scale scores and global improvement assessed by patients and gastroenterologists and change in the degree of interference in life caused by IBS symptoms assessed by patients. RESULTS: Compared with patients in the placebo group, patients in the active treatment groups (standard and individualized CHM) had significant improvement in bowel symptom scores as rated by patients (P=.03) and by gastroenterologists (P=.001), and significant global improvement as rated by patients (P=.007) and by gastroenterologists (P=.002). Patients reported that treatment significantly reduced the degree of interference with life caused by IBS symptoms (P=.03). Chinese herbal formulations individually tailored to the patient proved no more effective than standard CHM treatment. On follow-up 14 weeks after completion of treatment, only the individualized CHM treatment group maintained improvement. CONCLUSION: Chinese herbal formulations appear to offer improvement in symptoms for some patients with IBS.     

0D/2D Heterostructures Vertical Single Electron Transistor

Mixed-dimensional heterostructures formed by the stacking of 2D materials with nanostructures of distinct dimensionality constitute a new class of nanomaterials that offers multifunctionality that goes beyond those of single dimensional systems. An unexplored architecture of single electron transistor (SET) is developed that employs heterostructures made of nanoclusters (0D) grown on a 2D molybdenum disulfide (MoS₂) channel. Combining the large Coulomb energy of the nanoclusters with the electronic capabilities of the 2D layer, the concept of 0D–2D vertical SET is unveiled. The MoS₂ underneath serves both as a charge tunable channel interconnecting the electrode, and as bottom electrode for each v-SET cell. In addition, its atomic thickness makes it thinner than the Debye screening length, providing electric field transparency functionality that allows for an efficient electric back gate control of the nanoclusters charge state. The Coulomb diamond pattern characteristics of SET are reported, with specific doping dependent nonlinear features arising from the 0D/2D geometry that are elucidated by theoretical modeling. These results hold promise for multifunctional single electron device taking advantage of the versatility of the 2D materials library, with as example envisioned spintronics applications while coupling quantum dots to magnetic 2D material, or to ferroelectric layers for neuromorphic devices.     

Dual-eyes Vision-based Docking System for Autonomous Underwater Vehicle: an Approach and Experiments

A critical challenge for autonomous underwater vehicles (AUVs) is the docking operation for applications such as sleeping under the mother ship, recharging batteries, transferring data, and new mission downloading. The final stage of docking at a unidirectional docking station requires the AUV to approach while keeping the pose (position and orientation) of the vehicle within an allowable range. The appropriate pose therefore demands a sensor unit and a control system that have high accuracy and robustness against disturbances existing in a real-world underwater environment. This paper presents a vision-based AUV docking system consisting of a 3D model-based matching method and Real-time Multi-step Genetic Algorithm (GA) for real-time estimation of the robot’s relative pose. Experiments using a remotely operated vehicle (ROV) with dual-eye cameras and a separate 3D marker were conducted in a small indoor pool. The experimental results confirmed that the proposed system is able to provide high homing accuracy and robustness against disturbances that influence not only the captured camera images but also the movement of the vehicle. A successful docking operation using stereo vision that is new and novel to the underwater vehicle environment was achieved and thus proved the effectiveness of the proposed system for AUV.     

Combining multi-visual features for efficient indexing in a large image database

The optimized distance-based access methods currently available for multidimensional indexing in multimedia databases have been developed based on two major assumptions: a suitable distance function is known a priori and the dimensionality of the image features is low. It is not trivial to define a distance function that best mimics human visual perception regarding image similarity measurements. Reducing high-dimensional features in images using the popular principle component analysis (PCA) might not always be possible due to the non-linear correlations that may be present in the feature vectors. We propose in this paper a fast and robust hybrid method for non-linear dimensions reduction of composite image features for indexing in large image database. This method incorporates both the PCA and non-linear neural network techniques to reduce the dimensions of feature vectors so that an optimized access method can be applied. To incorporate human visual perception into our system, we also conducted experiments that involved a number of subjects classifying images into different classes for neural network training. We demonstrate that not only can our neural network system reduce the dimensions of the feature vectors, but that the reduced dimensional feature vectors can also be mapped to an optimized access method for fast and accurate indexing. Received 11 June 1998 / Accepted 25 July 2000 Published online: 13 February 2001     

A Novel and Simple Process for Nanosized Mg‐Mn Ferrite Preparation from Solution Combustion Method and Study of its Characteristics

A novel solution combustion method has been used to prepare Mg‐Mn ferrites of various compositions, Mg_0.9Mn_0.1Fe_1‐xO₄ where x = 0.2, 0.4, 0.6, 0.8, and the properties were investigated in the present work. Nano‐size Mg‐Mn ferrite particles with diameter in the range of 8~ 15 nm were successfully formed via this method. The combustion temperature of the oxidation‐reduction was apparently occurred at 200°C. The result of X‐ray diffraction (XRD) analysis indicated that the as‐burnt powder affords a pure single spinel ferrite phase at low temperature. The thermal analysis of nitrate–citrate gels was characterized by DTA‐TG. The TEM and SEM observations give the morphology and microstructure of the products. The dielectric properties of the sintered Mg‐Mn ferrites were investigated by using HP/Agilent 4291B RF impedence/material analyzer. It was found that there was no maximum dielectric loss within the measured frequency range until 1 GHz due to excellent compositional control in this method.     

The use of personal protective measures in control of malaria in a defined community

Malaria is one of the main health problems in the non-immune immigrant workers and army personnel of the malaria endemic areas in Myanmar. Due to changes in the vector bionomics and multiresistant strains of P. falciparum, chemoprophylaxis alone is not an effective means of control of malaria in them. So it is envisaged that the combined used of personal protective measures (deltamethrin impregnated bed-nets, scalves and hand-bands) and the chemoprophylaxis will be an effective means of control of malaria in the define group of people. The study also intended to find out the side effects of the deltamethrin and feasibility and acceptability of methods by the users. The study was conducted in Theini Township, Northern Shan State, from March to November 1993. The study population consisted of all ages of both sexes 554 and 440 persons in the test and control groups respectively. At the initial phase of the study, malaria infected persons from both the groups were treated. The experimental group received personal protective measures with impregnation of bed-nets using 25 mg ai/m2 of deltamethrin at 4 monthly intervals and the scarves and hand-bands at twice the concentration of the insecticides at monthly intervals. Chemoprophylaxis was given to both the groups at weekly intervals using age adjusted dosage of Pyrixine tablet (sulfadoxine-pyrimethamine). The parasitological, entomological, and epidemiological indices were collected at two month intervals in both the groups. The study clearly showed the impact of personal protective measures and chemoprophylaxis on malaria infection in the studied subjects. During the study period, the out patient malaria cases of the test group was 6% to 11.2% and that of the control group was 12% to 21.6% in Theini Hospital. The reinfection rate of the test group (0.9 to 4.7%) was also significantly lower than the control group (6.1 to 14.3%) from July to November. Acceptance of the treated bed-nets, scarves and hand-bands was high and good compliance was found in the follow up. The results of the study clearly showed that malaria can be controlled effectively in the defined group of persons for a malaria transmission season by using chemoprophylaxis and personal protective measures.     

Fabrication of microstructured optical fibers-part I: problem formulation and numerical modeling of transient draw process

Microstructured optical fibers (MOFs) achieve their desired performance via a pattern of holes that run along the length of the fiber. Varying the hole pattern allows a variety of optical effects to be produced. However, the original hole pattern within the preform may not be accurately transferred to the finished fiber due to the combined impact of material properties and the drawing conditions experienced during fabrication. In this two-part paper, the processes of drawing MOFs having arbitrary cross-sectional hole structures will be analyzed for the case of Newtonian materials. Part I presents a modeling formalism to describe the drawing processes, followed by a scaling analysis on a representative case, i.e., the nonisothermal drawing of an axisymmetric annular hollow fiber, to reveal the major factors influencing the drawing of both silica and polymer MOFs. By treating the primary draw process (i.e., from preform to intermediate cane) in fabricating polymer MOFs as a transient, isothermal problem, numerical simulations were carried out for an illustrative five-hole structure. The results revealed the central importance of any steep neck-down region on hole-shape deformation as well as the importance of forces additional to those associated with surface tension effects. Both experimental observations and numerical modeling show that a diversity of hole "activities" (both in a hole's relative size and shape) can occur when drawing MOFs. Part II will extend both the analysis and numerical modeling with a focus on the steady-state continuous draw process (i.e., from preform or cane to fiber). In parallel with this analysis, we also present experimental results for the drawing of polymethylmethacrylate (PMMA) MOFs.