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Progressive age-related changes in white matter morphometry and microstructure have been found throughout the brain. Both declines in white matter (WM) volume and deterioration of microstructural integrity have been observed. Predicting these changes across WM tracts and building an integrated model of age-related WM trajectories has proven challenging. While tractwise differences in volume and microstructural declines are common targets of investigation, there has been relatively little exploration into other attributes of tract morphology or its relation to microstructural measures in vivo. This study seeks to examine ten WM tracts for tract-wise differences in WM volume, length, the ratio of volume to length (VLR), and microstructural integrity as measured by fractional anisotropy (FA) and mean diffusivity (MD) using diffusion MRI data from the Human Connectome Project in Aging (HCP-A). From these measures, we analyzed relationships between morphometry and microstructure in the aging brain with the goal of laying the foundation for a unified model of age-related changes that relates WM microstructure/morphometry and developmental trajectories. Results indicated wide variation in rates and patterns of decline between tracts, as well as tract-specific interactions between tract VLR and microstructure. Robust sex differences were also identified. Our findings demonstrate the need for further exploration of the mechanisms behind both macro- and microstructural differences across the aging brain.

Contains fulltext : 291108.pdf (Publisher’s version ) (Open Access) Active surveillance may be a safe and effective treatment in oesophageal cancer patients with a clinically complete response after neoadjuvant chemoradiotherapy (nCRT). In the NOSANO-study we gained insight in patients' motive to opt for either an experimental treatment called active surveillance or for standard immediate surgery. Both qualitative and quantitative analyses methods were used. Forty patients were interviewed about their treatment preference, 3 months after completion of nCRT (T1). Data were recorded, transcribed verbatim and analysed according to the principles of grounded theory. In addition, at T1 and T2 (12 months after completion of nCRT) questionnaires on health-related quality of life, coping, anxiety and decisional regret (only T2) were administered. Interview data analyses resulted in a conceptual model with 'dealing with threat of cancer' as the central theme. Patients preferring active surveillance tend to cope with this threat by confiding in their bodies and good outcomes. Their mind-set is one of 'enjoy life now'. Patients preferring surgery tend to cope by minimizing uncertainty and eliminating the source of cancer. Their mind-set is one of 'don't give up, act now'. Furthermore, questionnaire results showed that patients with a preference for standard surgery had a lower quality of life. Patient preferences are individualized and thus difficult to predict. Our model can help healthcare professionals to determine patient preferences for treatment. Coping style and mind-set seem to be determining factors here.

Data Availability Statement: The data presented in this manuscript is available on request from the corresponding author. Copyright: © 2022 by the authors. The main problem of recycling aluminium scrap is the gradual accumulation of impurities, especially iron, which tend to form undesired intermetallic compounds that affect the integrity and the mechanical performance of the castings. In this paper, we aim to provide an overview on the topic of iron removal from aluminium melts through primary intermetallic precipitation and the progress made during the LiME Hub project to understand the process and to develop a more efficient procedure. We cover both thermodynamic analysis and experimental validation. We found that high shear melt conditioning technology enhances the typically slow nucleation and growth of the dense primary intermetallics, speeding up their sedimentation and allowing a faster removal of Fe from the melt by simple gravity sedimentation. It also promotes the formation of smaller and more compact Fe-rich intermetallics, allowing an increased volume fraction recovery and mitigating their effect of being present in the final castings. The technology is not limited to batch processing, with a 90% efficiency, but can also be applied to continuous melt treatment of aluminium scrap, with currently 60% efficiency, and could be combined with other solid–liquid separation techniques to increase the purification efficiency even more. EPSRC (UK) under grant number EP/N007638/1; European Commission under Grant No. 603577; Innovate UK under Project No.102797.

The cascade-emitted biphotons generated from the alkali metal atomic ensembles are an excellent entanglement resource which enables long-distance quantum communication. The communication of quantum information between distant locations can be realized by utilizing the low-loss telecom bandwidth in the upper transition of the cascaded photons in a fiber-based quantum network. Meanwhile, the infrared photon from the lower transition of this highly directional and frequency-correlated biphoton can be created under the four-wave mixing process and can be stored locally as a collective spin wave. Here we theoretically investigate the frequency entanglement of this biphoton and propose two approaches to remove their mutual correlations in frequency spaces. The first approach applies an optical cavity which modulates the biphoton spectrum into a more symmetric and narrow spectral function by multiplexing multiple atomic ensembles with phase compensation. The purity of single photon reaches up to $0.999$ and the entanglement entropy $S$ of the biphoton reduces to $0.006$, which is $200$ times smaller than the one without multiplexing. The other approach employs a symmetric pumping of the laser fields in two atomic ensembles, which leads to a moderate reduction of $S\sim 0.3$ when non-discrimination detection devices are used for both photons. An extremely low frequency entanglement implies an almost indistinguishable single photon source, which offers a potential resource for photonic quantum simulation and computation., Comment: 6 figures

Formation of biomolecular condensates constitutes an emerging mechanism for transcriptional regulation. Recent studies suggest that the co-condensation between transcription factors (TFs) and DNA can generate mechanical forces driving genome rearrangements. However, the reported forces generated by such protein-DNA co-condensation are typically below one piconewton (pN), questioning its physiological significance. Moreover, the force-generating capacity of these condensates in the chromatin context remains unknown. Using single-molecule biophysical techniques, we show that Sox2, a nucleosome-binding pioneer TF, forms co-condensates with DNA, thereby exerting considerable mechanical tension on DNA strands both in cis and trans. Sox2 can generate forces up to 7 pN—similar in magnitude to other cellular forces. Sox2:DNA condensates are highly stable, withstanding disruptive forces high enough to melt DNA. We find that the disordered domains of Sox2 are required for maximum force generation but not condensate formation per se. Finally, we show that nucleosomes dramatically attenuate the mechanical stress exerted by Sox2 via sequestering it from coalescing on bare DNA. Our findings reveal that TF-mediated DNA condensation can exert significant mechanical stress which can nonetheless be alleviated by the chromatin organization, suggesting a new function of eukaryotic chromatin in protecting the genome from potentially deleterious nuclear forces.

In this paper, we report on the fabrication of Ga-doped zinc oxide (GZO) channel ultraviolet (UV) phototransistors. Under dark measurement conditions, it is found that the values of μFE, VT, SS, and ION/IOFF of the fabricated device are 25.8 cm2/Vs, 0.35 V, 0.2 V/decade, and 1 × 105, respectively. Unpassivated devices have a negative VTH shift with positive bias stress, which results from the interactions of the moisture present in air with the GZO channel during the fabrication procedure and/or storage. Furthermore, it is found that the deep-UV to visible-rejection ratio can reach 1.1 × 102 for the fabricated phototransistor. These electro-optical properties indicate that the fabricated devices not only present good performance as thin-film transistors (TFTs), but are also useful for deep-UV light sensing applications.

The dental follicle (DF), most often associated with unerupted teeth, is a condensation of ectomesenchymal cells that surrounds the tooth germ in early stages of tooth development. In the present study, we aim to isolate epithelial stem-like cells from the human DF and explore their potential differentiation into salivary gland (SG) cells. We demonstrated the expression of stem cell–related genes in the epithelial components of human DF tissues, and these epithelial progenitor cells could be isolated and ex vivo expanded in a reproducible manner. The human DF-derived epithelial cells possessed clonogenic and sphere-forming capabilities, as well as expressed a panel of epithelial stem cell–related genes, thus conferring stem cell properties (hDF-EpiSCs). When cultured under in vitro 3-dimensional induction conditions, hDF-EpiSCs were capable to differentiate into SG acinar and duct cells. Furthermore, transplantation of hDF-EpiSC–loaded native de-cellularized rat parotid gland scaffolds into the renal capsule of nude mice led to the differentiation of transplanted hDF-EpiSCs into salivary gland–like cells. These findings suggest that hDF-EpiSCs might be a promising source of epithelial stem cells for the development of stem cell–based therapy or bioengineering SG tissues to repair/regenerate SG dysfunction.

The accumulation of iron in molten aluminium is one of the main concerns for the recycling and casting industries because it leads to the formation of undesirable Fe-rich intermetallic compounds which are detrimental to mechanical properties. Many methods have been developed in the past to reduce the iron accumulated in molten aluminium scrap, but they all suffer from poor efficiency. Hence, a more efficient method is urgently needed to mitigate the negative effect of high iron levels in the melt, thereby avoiding downgrading secondary aluminium to low quality products or the dilution with expensive primary aluminium. This contribution provides a study of the Fe-rich intermetallic compounds developed in aluminium casting alloys with high levels of Fe as a function of melt processing conditions. Results show that the formation of the Fe-compounds is not only dependent on the cooling rate and holding time before solidification, but more on the initial melt treatment as it enhances the nucleation and growth of the Fe-phases. Elemental addition of Mn leads to the formation of large and compact intermetallic particles, but at slow rate. Physical melt treatment by intensive high shearing produces a much faster nucleation and results in a fine dispersion of smaller iron containing intermetallic particles. The latter could be used either to increase the tolerance to iron contamination or to facilitate the iron removal process, providing huge benefits for the recyclability of scrap aluminium alloys as it would allow the transformation of low-grade feedstock into a low cost and small carbon footprint material for high quality castings.

According to Ministry of Health and Welfare of Taiwan, cancer has been one of the major causes of death in Taiwan since 1982. The Intensive-Modulated Radiation Therapy (IMRT) is one of the most important radiotherapies of cancers, especially for Nasopharyngeal cancers, Digestive system cancers and Cervical cancers. For patients, if they can receive the treatment at the earliest possibility while diagnosed with cancers, their survival rate increases. However, the discussion of effective patient scheduling models of IMRT to reduce patients' waiting time is still limited in literature. This study proposed a mathematical model to improve the efficiency of patient scheduling. The research was composed of two stages. In the first stage, the online stochastic algorithm was proposed to improve the performance of present scheduling system. In the second stage the impact of future treatment to reduce patients' waiting time was considered. A genetic algorithm (GA) was then proposed to solve the online stochastic scheduling problem. This research collected data from a practical medical institute and the proposed model was validated with real data. It contributes to both theory and practice by proposing a practical model to assist the medical institute in implementing patient scheduling in a more efficient manner.

Typhula incarnata, the causal agent of gray snow mold, is an important winter pathogen of turfgrasses in the northern United States. The relative susceptibility of cultivars of three bent-grass species (creeping, colonial, and velvet bentgrass) to Typhula incarnata and the aggressiveness of 15 T. incarnata isolates obtained from infected turfgrasses on golf courses in Michigan, Minnesota, and Wisconsin were evaluated under controlled conditions. A hypersensitive type of resistance response to T. incarnata was not observed in any cultivar. Disease severity increased with higher inoculum concentration of T. incarnata. Colonization by gray snow mold gradually decreased with increasing plant age from 11 weeks after seeding in most cultivars tested, suggesting that age-related resistance was expressed over time. There were significant differences in disease severity among the three bentgrass species, particularly between tetraploid (creeping and colonial) and diploid (velvet) species, and among cultivars within each species, indicating varying levels of susceptibility to T. incarnata. All 15 isolates were pathogenic on bentgrass and were significantly different in aggressiveness, but aggressiveness was not related to geographic origin. Therefore, turfgrass breeders should be able to use one or a few virulent representative isolates of the pathogen to screen for resistance.

Speckled snow mold, caused by Typhula ishikariensis, is one of the most important Typhula snow molds in subarctic zones of the Northern Hemisphere. Nine isolates of three T. ishikariensis varieties (var. ishikariensis, var. canadensis, and var. idahoensis) isolated from infected turfgrasses on golf course fairways throughout Wisconsin were evaluated for their aggressiveness toward nine cultivars of three bentgrass species (three creeping, three colonial, and three velvet cultivars) under controlled environmental conditions. Speckled snow mold severity increased as inoculum concentration of T. ishikariensis was increased. In general, bentgrass susceptibility increased between 9 and 11 weeks after seeding but gradually decreased thereafter, suggesting expression of age-related resistance as plants matured. Significant differences in aggressiveness were detected within and among T. ishikariensis varieties. Significant interactions between T. ishikariensis varieties or isolates and bentgrass species were detected, but there was no interaction between pathogen isolates and bentgrass cultivars. Disease severity evaluations showed significant differences among bentgrass cultivars and species in their response to T. ishikariensis. Since bentgrass species exhibit differential responses to T. ishikariensis varieties, representative isolates of each variety should be employed for screening of bentgrass germplasm for resistance to speckled snow mold.

We theoretically investigate the spectral property of biphoton state from the cascade emissions from a Doppler-broadened atomic ensemble. This biphoton state is spontaneously created in the four-wave-mixing process. The upper transition of the emissions lies in telecom bandwidth, which prevails in fiber-based quantum communication for low-loss transmission. We obtain the spectral property in terms of superradiant decay rates of the lower transition, excitation pulse durations, and temperature of the medium. We quantify their frequency entanglement by Schmidt decomposition and find that more entangled source can be generated with longer excitation pulses, enhanced decay rates, and significant Doppler broadening. A minimally entangled biphoton source can also be located at some optimal temperature of the atoms. This allows spectral shaping of continuous frequency entanglement, which is useful in multimode long-distance quantum communication., 4 figures

In animals, differentiation of germline from soma usually takes place during embryogenesis. Genes and their products that are preferentially expressed in the embryonic germ cells are regarded as candidates for maintaining germline fate or promoting germline identity. In Drosophila, for example, the protein encoded by the germline gene vasa is specifically restricted to the germ cells, while products of the gap gene hunchback (hb), a somatic gene, are preferentially expressed in the neuroblasts. In this study, we report the expression of both messenger RNA and protein encoded by Aphb, an hb orthologue in the asexual viviparous pea aphid Acyrthosiphon pisum, in germ cells as well as in neuroblasts. We infer that expression of Aphb messenger RNA in the germ cells during the formation of germaria is required for the anterior localization of Aphb in the protruding oocytes. Germarial expression and anterior localization of ApKrüppel was also identified but, unlike Aphb, its expression was not detected in the migrating germ cells. Very similar patterns of hb expression were also identified in the green peach aphid Myzus persicae, suggesting that germline expression of hb is conserved within the Aphididae. To date, this pattern of hb germline expression has not been reported in other insects.

Large ohmic losses in the cavities of terahertz gyrotrons may lead to the overlapping of the axial mode spectra. In a number of gyrotron experiments, this effect has been used to provide a fairly broadband frequency tuning by changing appropriately the operating magnetic field and/or accelerating voltage of the gyrotron. Similar to the systems with nonfixed axial structure of the RF electromagnetic field and low diffraction quality, which are due to weak reflections of the operating wave from the collector end of the electrodynamic system, this changing leads to a monotonic change in the axial index of the operating wave and transition from the gyrotron regime to the gyro-BWO regime. According to a theoretical comparison of these two methods performed on the basis of generalization of self-consistent gyrotron equations with allowance for variations in the axial electron momenta, low-reflection systems can provide a higher efficiency and monotonicity of the frequency tuning.

Eux(NH4)2-2xTi3O7 nanoporous phosphor was prepared by ion exchange method. (NH4)2Ti3O7 nanotubes were employed as the host structure by treating H2Ti3O7 with NH4OH solution and the activator, Eu2+, was introduced into the host via ion exchange. This is an easy and feasible way to prepare a phosphor. The synthesized samples were characterized using TEM, XRD, N2 adsorption-desorption isotherm, TPR, and fluorescence spectrophotometer. Experimental results showed that a portion of Eu2+ ions was oxidized into Eu3+ ions during ion exchange, resulting in the present phosphor with blue-emitting and red-emitting. Moreover, the tubular structure of Eux(NH4)2-2xTi3O7 was distorted as Eu2+ was placed into the host structure. This distortion is attributed to the electrostatic interaction between Eu2+ and the electric field of the host structure.

The authors report the fabrication of amorphous IGZO (a-IGZO) phototransistors with a thin Ga 2 O 3 layer. It was found that the performances of the phototransistors depend strongly on the oxygen partial pressure during the deposition of the Ga 2 O 3 layer. It was also found that the fabricated devices exhibited good electrical properties with electron mobility (μ FE ) of 13.2 cm 2 /V·s, subthreshold swing (SS) of 0.13 V/decade, and ON/OFF current ratio> 5 × 10 5 . Furthermore, it was found that two cutoffs exist in the devices prepared with 25% oxygen partial pressure. The deep-ultraviolet (UV)-to-visible rejection ratio and near-UV-to-visible rejection ratio of the fabricated phototransistors were 10 4 and 20, respectively.

A compact diffraction apparatus is developed with millimeter-wave propagation between two parallel plates. Two types of microfabricated model crystals are individually mounted on a rotatable structure. In contrast to previous work, the experimental results agree well with Bragg’s predictions because multiple scattering is minimized in this configuration. Factors that affect the resolution and signal strength, such as the number of scatterers, cylinder radius, and the distance between the detector and the model crystal, are analyzed. The apparatus offers a visually accessible way to teach students about crystal structure as well as scattering and diffraction.

External wrist fixators have been widely used to stabilize distal radial fractures. Ideally an external fixator would create a stable environment for the fracture to heal while allowing proper mobility for the wrist. However, this has been a great challenge to the designers.The current study aimed to develop a bridging wrist external fixator that is easy for surgeons to create a stable environment for the fracture to heal while allowing proper wrist mobility for rehabilitative purposes. The kinematic geometry of the wrist-fixator system was described using loop equations defined by homogeneous transformation matrices (HTM) of the joints involved, and was evaluated numerically for a set of system parameters that are determined by surgeons during surgery. The results were validated with geometric models and computer simulation. The contributions of individual clinical parameters to the kinematic geometry of the wrist-fixator system were also analyzed using the Taguchi method.Adequate pin placement and hinge alignment function were found to be critical for the postoperative bridged wrist motion. The results of the current study will be helpful for surgeons to perform fixation using the new wrist fixator and for designers to design new fixators in the future.

This paper analyses and compares several different synchronized controllers and motion command schemes, and implements them using a PC-based gantry-type machine tool. First, an integral-proportional (IP) controller and a proportional controller are applied to the velocity and position loop of a single-axis system respectively. The tracking control accuracy of the motor is advanced by the fastened response and improved lag. Next, for the dual-axis synchronized system, the equation of the cross-coupled controller (CCC) parameters can be acquired by analysing the tracking error and the synchronized error of the dual linear motors. The equation can be further applied to integrate the synchronized motion and reduce the synchronized error. The experiment results have proved these theories to be successful in reducing synchronized error and realizing the performance demand of tracking control.

Al matrix composites reinforced by Al–Cu–Fe quasicrystalline (QC) phase particles were produced from a mixture of Al and QC powders using electrical current heating and conventional sintering. A combination of X-ray diffractrometry, transmission and scanning electron microscopy was used to characterise the microstructure of consolidated specimens. The metallic bonding of the Al matrix and particles was improved by higher temperature sintering or electrical current heating. However, the dissolution of QC particles into the Al matrix was inevitable during heating and resulted in the formation of ω and/or β phases. The dissolution of QC particles was effectively reduced using prealloyed Al powder containing 2 at.-%Cu. This had led to an increase in microhardness from 96 to 139 HV for specimens using pure Al to prealloyed Al powders. A homogeneous distribution of QC particles within the Al matrix could be achieved by mechanical milling followed by consolidation.

Host parasitism by Trichomonas vaginalis is complex and in part mediated by adherence to vaginal epithelial cells (VECs). Four trichomonad surface proteins bind VECs as adhesins, and AP65 is a major adhesin with sequence identity to an enzyme of the hydrogenosome organelle that is involved in energy generation. In order to perform genetic analysis and assess the role of AP65 in T. vaginalis adherence, we silenced expression of ap65 using antisense RNA. The gene for ap65 was inserted into the vector pBS-neo in sense and antisense orientations to generate plasmids pBS-neoS (S) and pBS-neoAS (AS), respectively. Trichomonads were then transfected with S and AS plasmids for selection of stable transfectants using Geneticin, and the presence of plasmid in transfectants was confirmed by polymerase chain reaction of the neo gene. Reverse transcription polymerase chain reaction and Northern blot analysis showed decreased amounts of ap65 transcript in AS transfected parasites. Growth kinetics of the antisense-transfected and wild type organisms were similar, suggesting that silencing AP65 did not affect overall energy generation for growth. Immunoblot analysis using monoclonal antibody (mAb) to AP65 of AS transfectants showed decreased amounts of AP65 when compared to wild type or S transfectants. Not unexpectedly, this corresponded to decreased amounts of AP65 bound to VECs in a functional ligand assay. Reduction in parasite surface expression of AP65 was related to lower levels of adherence to VECs by AS-transfectants compared to control organisms. Antisense silencing of ap65 was not alleviated by growth of trichomonads in high iron, which up-regulates transcription of ap65. Our work reaffirms the role for AP65 as an adhesin, and in addition, we demonstrate antisense RNA gene silencing in T. vaginalis to study the contribution of specific genes in pathogenesis.

The study of swirl flow is of technical and scientific interest because it has an internal recirculation field, and its tangential velocity is related to the curvature of the streamline. The fluid flow for tubes and elbows of heat exchangers has been studied largely through experiments and numerical methods, but studies about swirl flow have been insufficient. Using the Particle Image Velocimetry method, this study found the time averaged velocity distribution, time averaged turbulence intensity with swirl and without swirl flow for Re = 10,000, 15,000, 20,000 and 25,000 along longitudinal sections, and the results appear to be physically reasonable. In addition, streamwise mean velocity distribution was compared with those of Khodadai et al. and Jeong et al.

Selective laser sintered Rapidsteel parts were sintered and infiltrated with Cu-10 at.-%Sn, in two different atmospheres (e.g. 30%H2-70%N2 and vacuum with a partial pressure of 200 mbar of Ar). The processing atmospherehada significant effect on the mechanical properties of the infiltrated parts. The parts intered/infiltrated in a 30%H2-70%N2 atmosphere, exhibited a tensile strength of 780 MPa and a ductility of 4.45%. However, the tensile strength was reduced moderately to 650 MPa while the ductility was increased significantly to 11.7% by changing the sintering/infiltration atmosphere from 30%H2-70%N2 to vacuum + Ar. Furthermore, the parts processed in a vacuum + Ar atmosphere exhibited a better fracture resistance than parts processed in 30%H2- 70%N2. The improvement in ductility and fracture resistance for parts processed in vacuum + Ar atmosphere was primarily due to the elimination of nitrides. For both cases, ductile fracture occurred in stainless steel particulate and striation was found i...

Some isolates of Trichomonas vaginalis, the number one, non-viral sexually transmitted disease agent, are infected with one or several distinct double stranded (ds)-RNA virus. Immune rabbit anti-capsid serum (IRS) reacted with the capsid protein of purified dsRNA virus of a subset of the virus-infected T. vaginalis isolates. A monoclonal antibody (mAb) that recognized the capsid protein reactive with the IRS was generated. Analysis of the virus capsid protein of virus-infected isolates by probing nitrocellulose blots with mAb revealed diversity among immunoreactivity and in the size of the reactive capsid protein. Despite difficulties in visualizing virus within parasites by cross-section electron microscopy, gold-conjugated mAb readily labeled the cytoplasm of virus-positive trichomonads. Finally and importantly, isolates infecting patients attending an STD clinic, 75% of which were virus-positive isolates, had capsid protein of the same size detected by mAb present in all dsRNA viruses.

Transmission electron microscopy has been used to reveal the microstructure of metastable C40 MoSi 2 thin films produced by annealing amorphous magnetron-sputtered deposits at 700°C. The films contain nanoscale acicular grains elongated parallel to (0001), with extensive basal faulting. The faults are intrinsic with R ´ 1/3[0001] and correspond to thin slabs of the equilibrium C11 b phase. It is proposed that these faults may act as nuclei for the subsequent transformation from C40 to C11 b by a process akin to discontinuous coarsening.

A hybrid 5-degrees-of-freedom parallel kinematic machine tool constructed using the TRR-XY mechanism has been used to investigate the theory of post-processing. The effects of the cutter shapes and machine construction on the post-processing are investigated. Some specific parameters only are required to modify the post-processing for the different tools used in real cutting. The tilt angle and yaw angle of the cutter relative to the normal direction of the cutting surface are included in the investigation. The parametric representations of different cutter shapes defined by the DIN standard were also adopted in the derivation. The generality of the post-processor theory developed was then increased. Finally, NC code has been generated using LABVIEW software. Simulations are performed to verify the correctness of the work based on several designed tool paths.

We have designed and built a low noise, broadband transimpedance amplifier that allows for sensing both the amplitude and phase of an oscillating quartz tuning fork for a cryogenic atomic force microscope. The circuit uses a global feedback scheme, where the input stage, located next to the quartz tuning fork at low temperature, is followed by an operational amplifier stage operated at room temperature. At 4.2 K, with a 1 MΩ metal film feedback resistor, the amplifier yields an output noise floor of 2×10−7 V/Hz and a bandwidth of 200 kHz. When it is used with a commercial 32 kHz quartz tuning fork, the calibrated sensitivity at 4.2 K is determined to be 30.8 μV/pm.

The parallel kinematic machine tool has many advantages including excellent loading capacity, high structural stiffness and small accumulated error of linkage. It has become one of the most important research fields for machine tools. In the present research, a principle for the optimization of the dimensional design parameters of a parallel kinematic machine tool is proposed. A five-degree-of-freedom (5DOF) parallel kinematic machine tool with a TRR-XY hybrid mechanism is chosen for investigating the design procedures and the optimization results. The inverse kinematics of the hybrid mechanism is first investigated. Then, the inverse solution is used to analyse and create the workspaces of the machine tool. The design parameters of the mechanical components are further optimized for constructing the maximum workspace.

Using parallel-link mechanism as the basic structure of the parallel kinematic machine (PKM) tool is a new design concept and has become one of the most important research fields, attracting many previous researchers. Research on the actuator driving force variation of a PKM tool is essential for the applications of a PKM tool to real machining processes. For machining a component, the smaller actuator driving force required means that the PKM tool has a higher machining performance. To improve the machining performance, understanding of the required actuator driving is very important. A generalized force analysis of the developed system was obtained using the Denavit-Hartenberg (D-H) notation method. The force reactions on the joints and actuator driving forces are obtained on the basis of various cutter locations and a given external cutting force. The prediction of the cutter location with the singularity condition can be also obtained on the basis of the infinite force of the joints. The geometry relationship between the tool platform and the links is adopted to verify the singularity conditions of the system. The driving force variation of the hybrid TRR- XY five-degree-of-freedom machine tool is further investigated.

The sixth Asian Symposium on Visualization (ASV6) was successfully held from May 28th to 31st, 2001 in Busan, Korea. The activities of the organizing committee and ASV6 programs are outlined here in retrospect and the philosophy of ASV6 is described.

platform. However, very few publications have dealt with the verification of error modelling methods for parallel machine tool structures. The machine tool studied is called a serial–parallel machine tool. It consists of serial units (X–Y table, column and slider) and a parallel shaft platform. In this study, the error model was derived using two methods, namely linkage kinematic error analysis and the differential vector method. The agreement of final forms is verified. Computational examples indicate some major factors contributing to inaccuracies.

Using a parallel link mechanism as the basic structure of the parallel link machine tool is a new design concept and has become one of the most important research fields and attracts many previous researchers. However, the application of these machines as a machine tool has not proven itself in terms of accuracy enhancement over traditional machine tools. In general, the geometry of the machine tool (moving platform size relative to base size) has significant effects on the level of accuracy achievable. Therefore, an error model analysis for the parallel link machine tool to take advantage of the geometry to minimize the error and to increase the accuracy is very important and interesting and is focused on in this research. A TRR-XY hybrid five-degree-of-freedom parallel link machine tool is built for this research to investigate the error model theory. The errors from the component machining and assembly are defined and considered in the inverse kinematic solution. The effects of the manufacturing errors on the accuracy of the machine tool are shown in this research.

The cutting force and the vibration signal of a computer numerical control (CNC) turning machine centre are detected for on-line tool wear monitoring. The feature elements are first extracted from the detected signals. The feature indices are obtained from the feature elements through data preprocessing. Six data fusion methods are used for integrating the feature indices to obtain the fusion indices. The obtained fusion indices are used as the input data of a neural network for online tool wear monitoring. The feasibility of coupling a neural network algorithm with different data fusion methods is investigated, based on the monitored data. The research results show that using a data fusion neural network in tool wear monitoring is feasible.

We have designed and fabricated a cryogenic scanning tunneling microscope for probing lithography defined nanometer-scale devices. The piezoelectric double tube is capable of scanning an area up to 22 μm×22 μm, while maintaining atomic resolution. In addition, the sample mount has a 5 mm×4 mm traveling range. Most importantly, the system is compact and, as a result, it can be inserted into the bore of a superconducting magnet. In this work, we demonstrate a unique application of scanning tunneling system, i.e., the scanning tip is in direct contact with the sample. The spectroscopic information therefore reflects the true characteristics of the devices under test, unlike the typical case where the tunneling barrier through vacuum imposes a large series resistance, on the order of 109 Ω. The design as well as the operation of this compact scanning tunneling microscope is described.