bluuebunny/crossref_metadata_2025 huggingface dataset:
Rural Informal Taxation in China: Historical Evolution and an Analytic Framework
Authors: Lin Justin Yifu , Liu Mingxing
Published: June 2007

The present paper examines the historical evolution of China's rural taxation system from the pre‐reform period to the late 1990s. We propose that because of information asymmetry between the upper‐level and the lower‐level governments, local governments had to be granted some informal tax autonomy to fulfill the upper‐level policy mandates. This easily led to excessive local informal taxation on farmers. As market liberalization of the grain sector progressed, the low‐cost tax instruments implemented through the traditional approach of implicit taxation gradually eroded. Local governments in agricultural regions had to resort to informal fees collected directly from individual rural households while the more industrialized regions shifted to non‐agricultural taxes that are less costly in terms of tax collection. Hence, political tension between farmers and local governments in agriculture‐based regions emerged and rural tax reform became necessary.
Product Formulation for Ohmic Heating: Blanching as a Pretreatment Method to Improve Uniformity in Heating of Solid–Liquid Food Mixtures
Authors: Sarang S. , Sastry S. K. , Gaines J. , Yang T. C. S. , Dunne P.
Published: June 2007

ABSTRACT:  The electrical conductivity of food components is critical to ohmic heating. Food components of different electrical conductivities heat at different rates. While equal electrical conductivities of all phases are desirable, real food products may behave differently. In the present study involving chicken chow mein consisting of a sauce and different solid components, celery, water chestnuts, mushrooms, bean sprouts, and chicken, it was observed that the sauce was more conductive than all solid components over the measured temperature range. To improve heating uniformity, a blanching method was developed to increase the ionic content of the solid components. By blanching different solid components in a highly conductive sauce at 100 °C for different lengths of time, it was possible to adjust their conductivity to that of the sauce. Chicken chow mein samples containing blanched particulates were compared with untreated samples with respect to ohmic heating uniformity at 60 Hz up to 140 °C. All components of the treated product containing blanched solids heated more uniformly than untreated product. In sensory tests, 3 different formulations of the blanched product showed good quality attributes and overall acceptability, demonstrating the practical feasibility of the blanching protocol.
Modeling the Irradiation Followed by Heat Inactivation of Salmonella Inoculated in Liquid Whole Egg
Authors: Álvarez I. , Niemira B.A. , Fan X. , Sommers C.H.
Published: June 2007

ABSTRACT:  This study presents mathematical models that describe the inactivation of Salmonella Enteritidis, Salmonella Typhimurium, and Salmonella Senftenberg suspended in liquid whole egg (LWE) by irradiation followed by heat treatments (IR‐H treatments). These models also enable prediction of cell injury in Salmonella after exposure to IR‐H. Salmonella viability decreased exponentially (primary model) with heat treating time for all the radiation doses (0, 0.1, 0.3, 0.5, 1.0, and 1.5 kGy) and temperatures investigated (55, 57, and 60 °C). Two secondary models that related the DT values (time required to eliminate 90% of viable cells at a given temperature) with radiation dose, heating temperature, and recovery medium after treatments were also developed. The developed final equations enabled to establish the process criterion (combinations of irradiation doses, temperature, and heat treatment times) required to achieve a given reduction (performance criterion) in Salmonella spp. suspended in LWE or the cell damage caused by the treatments. Process criteria to obtain the established performance criteria (a 5‐log10 reduction) on any of the investigated Salmonella serovars were determined to be, 57.7 °C/3.5 min following 1.5 kGy when treated cells were recovered in tryptic soy agar and 59.3 °C/3.5 min following 0.5 kGy when cells were recovered in tryptic soy agar amended with 3% NaCl. Based on our results, current industrial LWE heat treatments (60 °C/3.5 min) would inactivate 3 log10 cycles of the Salmonella population. The results of this study can be applied to engineering design and for the evaluation and optimization of the IR‐H process as a new technique to obtain Salmonella‐free LWE.
Effect of pH on the Taste of Alkaline Electrolyzed Water
Authors: Koseki M. , Tanaka Y. , Noguchi H. , Nishikawa T.
Published: June 2007

ABSTRACT:  The pH dependence of the taste of alkaline electrolyzed water (AEW) made by electrolyzing bottled mineral waters was examined by sensory evaluation. For water with a calcium concentration of 79 or 93 mg/L, the taste of AEW with a pH of 9.5 was considered better than that of the unelectrolyzed water. In contrast, for water with a calcium concentration of 10 mg/L, the taste of the unelectrolyzed water was preferred to that of AEW with a pH of 9.5. Electrolysis reduced the calcium concentrations in waters with calcium concentrations of 79 or 93 mg/L, but did not change the calcium concentration in water with a calcium concentration of 10 mg/L. Electrolysis probably improved the taste of water with a higher calcium concentration by reducing the calcium concentration; however, the effect of electrolysis on water with a calcium concentration of 10 mg/L is likely to be the result of the pH increase alone.
Survey of Antimicrobial Effects of Beef Carcass Intervention Treatments in Very Small State‐Inspected Slaughter Plants
Authors: Algino R.J. , Ingham S.C. , Zhu J.
Published: June 2007

ABSTRACT:  U.S. beef slaughter facilities are required to use a carcass intervention treatment to reduce contamination by Escherichia coli O157:H7. Very small beef slaughter operators generally are unable to carry out challenge studies to validate intervention treatment effectiveness, and in‐plant pathogen challenge studies are not permitted. The objective of this study was to evaluate the effectiveness, measured by decreases in generic E. coli, coliforms, Enterobacteriaceae, and aerobic plate count, of intervention treatments used at very small beef slaughter facilities in Wisconsin. Over a 9‐mo period, 265 head of beef were sampled at 22 very small beef slaughter facilities before and after the intervention treatment. The interventions studied were dry‐aging, low‐pressure hot‐water spray, high‐pressure hot‐water spray, 2.5% acetic acid spray, and Fresh Bloom™ (a mix of citric acid, ascorbic acid, and erythorbic acid) spray. Sprays were applied using a hand‐held nozzle (hot water) or a pump‐type sprayer (acid). There was no significant difference (P > 0.10) between intervention treatments and all treatments caused significant reductions (P < 0.10) in indicator organisms. Ranges in average reductions for generic E. coli, coliforms, and Enterobacteriaceae among the treatments were 0.6 to 2.0 log CFU/cm2, 0.7 to 2.2 log CFU/cm2, and 0.4 to 2.2 log CFU/cm2, respectively. For all treatments, rapid decreases in cooler temperature and relative humidity significantly affected indicator reduction, and for hot‐water washing, increasing spray time led to significantly greater reductions. Further studies using actual or simulated very‐small‐plant intervention treatments directly against E. coli O157:H7 would provide additional validation of treatment efficacy.
A Contribution to the Understanding of Psychosomatic Processes in Groups
Authors: Brown Dennis G.
Published: June 2007

It is proposed that Group Analysis, theoretically and practically, provides a useful approach to the study and treatment of psychosomatic problems. It highlights the struggle to move from a restricted internalisation and somatisation of emotional difficulties to their understanding and resolution within a new network of relationships (the therapeutic group). This throws into relief and reveals their origin in the world of internal objects and the pervading social matrix, as well as in the individual's current life situation.

Further communication and verbalisation are encouraged by the example of others in the group, especially by those who have already trodden the path from somatisation to fuller expression of themselves. A clinical example is used to illustrate this process, the difficulties are discussed and the need for a range of treatments, physical, individual and group emphasised.
Importance of inhibitor of DNA binding/differentiation 2 in hepatic stellate cell differentiation and proliferation
Authors: Tajima Kunihiko , Terai Shuji , Takami Taro , Kawaguchi Kotaro , Okita Kiwamu , Sakaida Isao
Published: June 2007

Background/Aim:  In liver fibrosis, activated hepatic stellate cells (HSC) are transformed into myofibroblasts. Helix‐loop‐helix (HLH) transcriptional factors such as MyoD regulate the differentiation of myocytes, and the inhibitor of DNA binding/differentiation (Id) family comprises dominant negative HLH transcriptional regulators that inhibit differentiation and promote cell proliferation. In the present study, we investigated how the Id family proteins regulate HSC.

Methods:  In primary rat HSC, inhibitor of DNA binding/differentiation (Id)2 and α‐smooth muscle actin (α‐SMA) mRNA expression increased 4 days after isolation. Next we established Id2 expressing HSC (HSC‐T6‐Id2‐green fluorescent protein (GFP)) using HSC‐T6 cells with retrovirus that expressed GFP‐tagged Id2.

Results:  HSC‐T6‐Id2‐GFP increased cell proliferation with cyclin D1 expression. In contrast, α‐SMA expression wassuppressed. Real‐time reverse transcription–polymerase chain reaction analysis showed Id2 induction significantly suppressed α‐SMA, collagen‐1, matrix metalloproteinase (MMP)‐2, and MMP‐9 mRNA (P < 0.05) but had no effect on tissue inhibitor of metalloproteinase or transforming growth factor‐β1 levels.

Conclusion:  These findings suggest Id2, an HLH transcriptional regulator, plays an important regulatory role in the proliferation and differentiation of HSC.
Supervisory Factory Control Based on Real-Time Production Feedback
Authors: Chang Qing , Ni Jun , Bandyopadhyay Pulak , Biller Stephan , Xiao Guoxian
Published: June 2007

One key characteristic of any process performance is variability; that is, a process rarely performs consistently over time. The bottleneck is one of the main reasons causing the system variability and fluctuation in production. Short-term production analysis and short-term bottleneck identification are imperative to enable manufacturing operations to optimally respond to dynamic changes in system behavior. However, conventional throughput and bottleneck analysis focus on long-term statistic bottleneck identification, which is usually not applicable to a short-term period. An on-line supervisory control method is introduced to search for short-term production constraints with unknown machine reliability distribution and mitigate those constraints to improve system throughput. The control mechanism uses playback simulation of the real production data to identify the bottleneck station, and control parameters of that station to reach a near balanced production line operation by understanding the bottleneck inertia phenomenon. The results ensure the smooth flow of products on the production line and increase the line’s performance.
Reconfigurable Pin-Type Tooling: A Survey of Prior Art and Reduction to Practice
Authors: Munro Chris , Walczyk Daniel
Published: June 2007

The idea of using a bed-of-pins as a completely reconfigurable discrete tool surface (referred to as a reconfigurable pin-type tool) for forming or molding of mechanical components has been around for at least 140years. Interestingly, the state-of-the-art today differs little from early patents except for the introduction of powered actuation and computer control. To help explain why this promising manufacturing technology is not used more extensively in industry, this paper attempts to tell a complete story about reconfigurable pin-type tooling through analysis of the state-of-the-art academic and industrial research, and commercialization of the concept from the original patented concept in 1863. The authors begin by defining what a reconfigurable tool is and by describing what characteristics an ideal reconfigurable tool should have. Next, the history of reconfigurable tooling patents from 1863 to 2003 and related research from the late 1960s to the present is recounted. One major research effort that eventually led to the development of a commercial project was the U.S. government-sponsored Reconfigurable Tooling for Flexible Fabrication project. A critical analysis shows that the state-of-the-art in reconfigurable pin-type tooling meets all specifications of the defined “ideal tool” with the exception of spatial resolution and weight. Finally, the reserved response by industry to adopt reconfigurable pin-type tooling and future of reconfigurable tooling is discussed.
Ultrasonic Cavitation Based Nanomanufacturing of Bulk Aluminum Matrix Nanocomposites
Authors: Yang Yong , Li Xiaochun
Published: June 2007

Lightweight metal–matrix nanocomposites (MMNCs) (metal matrix with nanosized ceramic particles) can be of significance for automobile, aerospace, and numerous other applications. It would be advantageous to develop effective nanomanufacturing methods for fabrication of bulk components of aluminum based MMNCs through solidification processing. However, it is extremely difficult to disperse nanosized ceramic particles uniformly in molten aluminum. In this paper, a high power ultrasonic probe is used to disperse nanosized SiC particles into molten aluminum alloy A356. Experimental results show that the ultrasonic cavitation based dispersion of nanoparticles in molten aluminum alloy is effective. The uniform nanoparticle dispersion in the Al alloy matrix resulted in significantly improved mechanical properties. To enhance the nanomanufacturing efficiency, various nanoparticle feeding techniques were explored and experimental results are presented.
Model-Based Analysis of the Surface Generation in Microendmilling—Part I: Model Development
Authors: Liu Xinyu , DeVor Richard E. , Kapoor Shiv G.
Published: June 2007

This paper presents the development of models that describe the surface-generation process for microendmilling. The surface-generation models for the sidewall and floor surfaces consist of deterministic and stochastic models. In the sidewall surface-generation model, the deterministic model characterizes the surface topography generated from the relative motion between the major cutting edge and the workpiece material. The model includes the effects of the process kinematics, dynamics, tool edge serration, and process faults (e.g., tool tip runout). The stochastic model predicts the increased surface roughness generated from ploughing due to the significant tool edge radius effect. In the floor surface-generation model, the deterministic model characterizes the three-dimensional surface topography over the entire floor surface and considers the effects of the minimum chip thickness, the elastic recovery, and the transverse vibration. The variation of the ploughing amount across the swept arc of the cutter due to the varying chip load conditions is considered in the stochastic model.
Maintenance Opportunity Planning System
Authors: Chang Qing , Ni Jun , Bandyopadhyay Pulak , Biller Stephan , Xiao Guoxian
Published: June 2007

Timely performance of preventive maintenance (PM) tasks is a critical element of manufacturing systems. Since the majority of PM tasks requires that equipment be stopped, these tasks can generally only be performed during nonproduction shifts, breaks, or other scheduled downtime. Thus, there is a trade-off between time dedicated to production and time available for preventive maintenance. One approach to mitigate this trade-off is to perform maintenance during scheduled production time by strategically shutting down equipment for short time periods. This research developed a systematic method on when to shut down equipment to do maintenance in an automotive assembly environment. It is called maintenance opportunity. The method incorporated real-time information about production and machine failure conditions. A simulation-based algorithm is developed by utilizing the buffer contents as well as machine starvation and congestion to obtain maintenance opportunities during production time.
The Effect of Nonconventional Laser Beam Geometries on Stress Distribution and Distortions in Laser Bending of Tubes
Authors: Safdar Shakeel , Li Lin , Sheikh M. A. , Liu Zhu
Published: June 2007

Laser forming is a spring-back-free noncontact forming method that has received considerable attention in recent years. Compared to mechanical bending, no hard tooling, dies, or external force is used. Within laser forming, tube bending is an important industrial activity with applications in critical engineering systems such as heat exchangers, hydraulic systems, boilers, etc. Laser tube bending utilizes the thermal stresses generated during laser scanning to achieve the desired bends. The parameters varied to control the process are usually laser power, beam diameter, scanning velocity, and the number of scans. The thermal stresses generated during laser scanning are strongly dependent upon laser beam geometry. The existing laser bending methods use either circular or rectangular beams. These beam geometries sometimes lead to undesirable effects such as buckling and distortion in tube bending. This paper investigates the effects for various laser beam geometries on laser tube bending. Finite element modeling has been used for the study of the process with some results also validated by experiments.
A Time Domain Dynamic Simulation Model for Stability Prediction of Infeed Centerless Grinding Processes
Authors: Li Hongqi , Shin Yung C.
Published: June 2007

This paper presents a comprehensive dynamic model that simulates infeed centerless grinding processes and predicts their instability-related characteristics. The new model has the unique ability of accurately predicting the coupled chatter and lobing process of a multi-degree of freedom and two-dimensional centerless grinding system by considering its critical issues. First, the model considers the complete two-dimensional kinematics, dynamics, surface profiles, and the geometrical interactions of the workpiece with the grinding wheel, regulating wheel, and supporting blade. Second, a two-dimensional distributed grinding force model along the contact length is adopted and modified for centerless grinding processes as a function of normalized uncut chip thickness. The forces of the work holding system are determined by balancing the grinding force and accordingly the work holding instability can be identified as well. Third, a two-dimensional contact deformation model under the condition of general surface profiles or pressure distributions is developed for the contacts of the workpiece with the grinding wheel, regulating wheel, and supporting blade. The new model is validated by comparing the predicted chatter and lobing occurrences with experimental results.
Enhanced Heat Transfer Using Porous Carbon Foam in Cross Flow—Part I: Forced Convection
Authors: Jamin Yorwearth L. , Mohamad Abdulmajeed A.
Published: June 2007

Cogeneration of heat and power has become standard practice for many industrial processes. Research to reduce the thermal resistance in heat exchangers at the gas/solid interface can lead to greater energy efficiency and resource conservation. The main objective of this experimental study is to quantify and compare the heat transfer enhancement of carbon foam and aluminum fins. The study measures the heat transfer rate and pressure drop from a heated vertical pipe, with and without porous medium, in forced convection. The largest increase in Nusselt number was achieved by aluminum fins, which was about three times greater than the best carbon foam case.
Computation of Flow and Heat Transfer in Rotating Rectangular Channels (AR=4:1) With Pin-Fins by a Reynolds Stress Turbulence Model
Authors: Su Guoguang , Chen Hamn-Ching , Han Je-Chin
Published: June 2007

Computations with multi-block chimera grids were performed to study the three-dimensional turbulent flow and heat transfer in a rotating rectangular channel with staggered arrays of pin-fins. The channel aspect ratio (AR) is 4:1, the pin length to diameter ratio (H∕D) is 2.0, and the pin spacing to diameter ratio is 2.0 in both the stream-wise (S1∕D) and span-wise (S2∕D) directions. A total of six calculations have been performed with various combinations of rotation number, Reynolds number, and coolant-to-wall density ratio. The rotation number and inlet coolant-to-wall density ratio varied from 0.0 to 0.28 and from 0.122 to 0.20, respectively, while the Reynolds number varied from 10,000 to 100,000. For the rotating cases, the rectangular channel was oriented at 150deg with respect to the plane of rotation to be consistent with the configuration of the gas turbine blade. A Reynolds-averaged Navier-Stokes (RANS) method was employed in conjunction with a near-wall second-moment turbulence closure for detailed predictions of mean velocity, mean temperature, and heat transfer coefficient distributions.
Dose comparison of megavoltage cone‐beam and orthogonal‐pair portal images
Authors: Peng Lee‐Cheng , Yang Ching‐Chong Jack , Sim Sang , Weiss Mitchell , Bielajew Alex
Published: June 2007

The technique of megavoltage cone‐beam computed tomography (MV CBCT) is available for image‐guided radiation therapy to improve the accuracy of patient setup and tumor localization. However, development of strategies to efficiently and effectively implement this technique or to replace the current orthogonal portal images technique remains challenging in the clinical environment. It is useful to compare the difference in absorbed dose between the MV CBCT technique and the orthogonal portal images technique, the current standard practice for treatment verification. Our study analyzed the doses generated from these two imaging techniques for six treatment sites (pelvis, abdomen, lung, head and neck, breast, prostate). The analysis was made by simulating the MV CBCT technique with an arc beam and a beam‐on time of 9 monitor units (MUs), and the orthogonal pair technique with a double‐exposure anterior–posterior and lateral pair and a beam‐on time of 4 MUs. The results are presented as dose per MU (cGy/MU) and absolute dose (cGy). The isocenter doses, integral doses, maximum doses, and mean doses to tumor and critical organs, and the two‐dimensional isodose distributions and dose–volume histograms of each critical organ were investigated. The absolute dose difference between MV CBCT and orthogonal pair at the isocenter was cGy. Major differences were seen between the two techniques in critical organs whose locations are away from the tumor. These organs, such as the contralateral breast (difference: cGy/MU) and lung (difference: cGy/MU), receive a higher dose from MV CBCT images than from orthogonal portal images. Additionally, higher doses and larger dose areas involving more normal tissues were observed for MV CBCT images than for orthogonal portal images in our analysis methodology, which used 200 beam projections delivered from various angles for the MV CBCT simulation and from just two perpendicular angles for the orthogonal pair simulation. In our selected clinical cases, the high‐dose area from the orthogonal pair technique was always located inside the tumor; with MV CBCT, the high‐dose area will most likely be outside the tumor. Therefore, the potentially higher doses to critical organs from MV CBCT images should be properly analyzed to ensure that they do not exceed the tolerance dose when therapy is delivered using that technique. On the other hand, to obtain good image quality, the higher MUs with MV CBCT images may be necessary. The absorbed dose for the tumor and for other critical organs should be calculated accordingly in the treatment plans. Images by MV CBCT are a great tool for three‐dimensional verification of patient treatment position. The trade‐off is that the MV CBCT technique for patient treatment verification might have a higher chance of increasing the dose to normal tissue during image acquisition.

PACS number: 87.53.Oq
Effect of bladder filling on doses to prostate and organs at risk: a treatment planning study
Authors: Moiseenko Vitali , Liu Mitchell , Kristensen Sarah , Gelowitz Gerald , Berthelet Eric
Published: June 2007

In the present study, we aimed to evaluate effects of bladder filling on dose–volume distributions for bladder, rectum, planning target volume (PTV), and prostate in radiation therapy of prostate cancer. Patients were scanned with a full bladder, and after 1 hour, having been allowed to void, with an empty bladder. Radiotherapy plans were generated using a four‐field box technique and dose of 70 Gy in 35 fractions. First, plans obtained for full‐ and empty‐bladder scans were compared. Second, situations in which a patient was planned on full bladder but was treated on empty bladder, and vice versa, were simulated, assuming that patients were aligned to external tattoos. Doses to the prostate [equivalent uniform dose (EUD)], bladder and rectum [effective dose ], and normal tissue complication probability (NTCP) were compared. Dose to the small bowel was examined. Mean bladder volume was 354.3 cm3 when full and 118.2 cm3 when empty. Median prostate EUD was 70 Gy for plans based on full‐ and empty‐bladder scans alike. The median rectal was 55.6 Gy for full‐bladder anatomy and 56.8 Gy for empty‐bladder anatomy, and the corresponding bladder was 29.0 Gy and 49.3 Gy respectively. In 1 patient, part of the small bowel (7.5 cm3) received more than 50 Gy with full‐bladder anatomy, and in 6 patients, part received more than 50 Gy with empty‐bladder anatomy. Bladder filling had no significant impact on prostate EUD or rectal . A minimal volume of the small bowel received more than 50 Gy in both groups, which is below dose tolerance. The bladder was higher with empty‐bladder anatomy; however, the predicted complication rates were clinically insignificant. When the multileaf collimator pattern was applied in reverse, substantial underdosing of the planning target volume (PTV) was observed, particularly for patients with prostate shifts in excess of 0.5 cm in any one direction. However, the prostate shifts showed no correlation with bladder filling, and therefore the PTV underdosing also cannot be related to bladder filling. For some patients, bladder dose–volume constraints were not fulfilled in the worst‐case scenario—that is, when a patient planned with full bladder consistently arrived for treatment with an empty bladder.

PACS numbers: 87.53.‐j, 87.53.Kn, 87.53.Tf
Dosimetric characteristics of a cubic‐block‐piled compensator for intensity‐modulated radiation therapy in the Pinnacle radiotherapy treatment planning system
Authors: Sasaki Koji , Obata Yasunori
Published: June 2007

We examined the dose distributions generated by (Philips Radiation Oncology Systems, Milpitas, CA) for intensity‐modulated radiotherapy (IMRT) plans using a cubic‐block‐piled compensator as the intensity modulator for 4‐MV and 10‐MV photon beams. The Pinnacle treatment planning system (TPS) uses an algorithm in which only the physical density of the absorber is required for calculating the characteristics of the modulator. The intensity modulator consists of cubic blocks (attenuator) of a tungsten alloy, plus cubic blocks of polyethylene resin foam that fill the spaces between the attenuator blocks and polymethyl methacrylate (PMMA) boards that act as the platform for the modulator. By measuring the transmission for various thicknesses of attenuator and by deriving values for the total physical density of the modulator, we determined the optimal effective density by comparing the curves fitted for the actual transmission data with the transmission calculated by the TPS. Using these effective densities, we examined the accuracy of for dose profiles of specific geometric patterns. The levels of consistency between the measurements and the calculations were within a tolerance of 3% of the dose difference and had a 3‐mm distance to agreement for the ladder‐, stairstep‐, and pyramid‐shaped test patterns, except in the high dose gradient region. In this modulator assembly, leakage occurred from the slits between the cubic blocks. This leakage was about 1.6% at maximum, and its influence on dose distribution was not crucial. In the TPS, in which physical density was the only user‐controllable parameter, we used the effective density of the absorber deduced from the effective mass attenuation coefficient. We conclude that the intensity modulation compensator system, together with a piled cubic attenuator, is clinically applicable, with an acceptable tolerance level. For the intensity map of the IMRT plan, measurements in treatment fields met 3% and 3‐mm criteria, excluding some regions of high gradient, which had a discrepancy of less than 5% and 4 mm.

PACS numbers: 87.53.Mr, 87.53.Tf
Evaluation of the analytical anisotropic algorithm in an extreme water–lung interface phantom using Monte Carlo dose calculations
Authors: Gagné Isabelle Marie , Zavgorodni Sergei
Published: June 2007

Our study compares the performance of the analytical anisotropic algorithm (AAA), a new superposition–convolution algorithm recently implemented in the Eclipse (Varian Medical Systems, Palo Alto, CA) Integrated Treatment Planning System (TPS), to that of the pencil beam convolution (PBC) algorithm in an extreme (C‐shaped, horizontal and vertical boundaries) water–lung interface phantom. Monte Carlo (MC) calculated dose distributions for a variety of clinical beam configurations at nominal energies of 6‐MV and 18‐MV are used as benchmarks in the comparison. Dose profiles extracted at three depths (4, 10, and 16 cm), two‐dimensional (2D) maps of the dose differences, and dose difference statistics are used to quantify the accuracy of both photon‐dose calculation algorithms. Results show that the AAA is considerably more accurate than the PBC, with the standard deviation of the dose differences within a region encompassing the lung block reduced by a factor of 2 and more. Confidence limits with the AAA were 4% or less for all beam configurations investigated; with the PBC, confidence limits ranged from 3.5% to 11.2%. Finally, AAA calculations for the small 18‐MV beam, which is poorly modeled by PBC (dose differences as high as 16.1%), provided the same accuracy as the PBC model of the 6‐MV beams commonly acceptable in clinical situations.

PACS number: 87.53.Bn
How image quality affects determination of target displacement when using kilovoltage cone‐beam computed tomography
Authors: Oh Seungjong , Kim Siyong , Suh Tae‐Suk
Published: June 2007

The advent of kilovoltage cone‐beam computed tomography (CBCT) integrated with a linear accelerator allows for more accurate image‐guided radiotherapy (IGRT). The IGRT technique corrects target displacement based on internal body information obtained by acquiring the CBCT image set and registering it with the simulation CT image set just before the beam is delivered. In the present paper, we compare registration results by CBCT reconstruction quality (either high or medium). We analyzed data from a total of 56 CBCT projections from 6 patients. The translational vector differences were within 1 mm in all but 3 cases. The rotational displacement differences considered components of all three axes, and in 3 of 168 cases (56 projections by 3 axes), showed more than 1 degree of difference.

PACS number: 87.57.Nk
Coherence Dynamics in Photosynthesis: Protein Protection of Excitonic Coherence
Authors: Lee Hohjai , Cheng Yuan-Chung , Fleming Graham R.
Published: June 2007

The role of quantum coherence in promoting the efficiency of the initial stages of photosynthesis is an open and intriguing question. We performed a two-color photon echo experiment on a bacterial reaction center that enabled direct visualization of the coherence dynamics in the reaction center. The data revealed long-lasting coherence between two electronic states that are formed by mixing of the bacteriopheophytin and accessory bacteriochlorophyll excited states. This coherence can only be explained by strong correlation between the protein-induced fluctuations in the transition energy of neighboring chromophores. Our results suggest that correlated protein environments preserve electronic coherence in photosynthetic complexes and allow the excitation to move coherently in space, enabling highly efficient energy harvesting and trapping in photosynthesis.
Processing of Capsid Protein by Cathepsin L Plays a Crucial Role in Replication of Japanese Encephalitis Virus in Neural and Macrophage Cells
Authors: Mori Yoshio , Yamashita Tetsuo , Tanaka Yoshinori , Tsuda Yoshimi , Abe Takayuki , Moriishi Kohji , Matsuura Yoshiharu
Published: June 2007

The flavivirus capsid protein not only is a component of nucleocapsids but also plays a role in viral replication. In this study, we found a small capsid protein in cells infected with Japanese encephalitis virus (JEV) but not in the viral particles. The small capsid protein was shown to be generated by processing with host cysteine protease cathepsin L. An in vitro cleavage assay revealed that cathepsin L cleaves the capsid protein between amino acid residues Lys
18
and Arg
19
, which are well conserved among the mosquito-borne flaviviruses. A mutant JEV resistant to the cleavage of the capsid protein by cathepsin L was generated from an infectious cDNA clone of JEV by introducing a substitution in the cleavage site. The mutant JEV exhibited growth kinetics similar to those of the wild-type JEV in monkey (Vero), mosquito (C6/36), and porcine (PK15) cell lines, whereas replication of the mutant JEV in mouse macrophage (RAW264.7) and neuroblastoma (N18) cells was impaired. Furthermore, the neurovirulence and neuroinvasiveness of the mutant JEV to mice were lower than those of the wild-type JEV. These results suggest that the processing of the JEV capsid protein by cathepsin L plays a crucial role in the replication of JEV in neural and macrophage cells, which leads to the pathogenesis of JEV infection.
Hepatitis B Virus Maturation Is Sensitive to Functional Inhibition of ESCRT-III, Vps4, and γ2-Adaptin
Authors: Lambert Carsten , Döring Tatjana , Prange Reinhild
Published: June 2007

Hepatitis B virus (HBV) is an enveloped DNA virus that presumably buds at intracellular membranes of infected cells. HBV budding involves two endocytic host proteins, the ubiquitin-interacting adaptor γ2-adaptin and the Nedd4 ubiquitin ligase. Here, we demonstrate that HBV release also requires the cellular machinery that generates internal vesicles of multivesicular bodies (MVBs). In order to perturb the MVB machinery in HBV-replicating liver cells, we used ectopic expression of dominant-negative mutants of different MVB components, like the ESCRT-III complex-forming CHMP proteins and the Vps4 ATPases. Upon coexpression of mutated CHMP3, CHMP4B, or CHMP4C forms, as well as of ATPase-defective Vps4A or Vps4B mutants, HBV assembly and egress were potently blocked. Each of the MVB inhibitors arrested virus particle maturation by entrapping the viral core and large and small envelope proteins in detergent-insoluble membrane structures that closely resembled aberrant endosomal class E compartments. In contrast, HBV subvirus particle release was not affected by MVB inhibitors, hinting at different export routes used by viral and subviral particles. To further define the role γ2-adaptin plays in HBV formation, we examined the effects of its overexpression in virus-replicating cells. Intriguingly, excess γ2-adaptin blocked HBV production in a manner similar to the actions of CHMP and Vps4 mutants. Moreover, overexpressed γ2-adaptin perturbed the endosomal morphology and diminished the budding of a retroviral Gag protein, implying that it may act as a principal inhibitor of the MVB sorting pathway. Together, these results demonstrate that HBV exploits the MVB machinery with the aid of γ2-adaptin.
Borna Disease Virus Infection Impairs Synaptic Plasticity
Authors: Volmer Romain , Prat Christine M. A. , Le Masson Gwendal , Garenne André , Gonzalez-Dunia Daniel
Published: June 2007

The mechanisms whereby
Borna disease virus
(BDV) can impair neuronal function and lead to neurobehavioral disease are not well understood. To analyze the electrophysiological properties of neurons infected with BDV, we used cultures of neurons grown on multielectrode arrays, allowing a real-time monitoring of the electrical activity across the network shaped by synaptic transmission. Although infection did not affect spontaneous neuronal activity, it selectively blocked activity-dependent enhancement of neuronal network activity, one form of synaptic plasticity thought to be important for learning and memory. These findings highlight the original mechanism of the neuronal dysfunction caused by noncytolytic infection with BDV.
Efficient In Vitro Amplification of Chronic Wasting Disease PrP
RES
Authors: Kurt Timothy D. , Perrott Matthew R. , Wilusz Carol J. , Wilusz Jeffrey , Supattapone Surachai , Telling Glenn C. , Zabel Mark D. , Hoover Edward A.
Published: June 2007

Chronic wasting disease (CWD) of cervids is associated with conversion of the normal cervid prion protein, PrP
C
, to a protease-resistant conformer, PrP
CWD
. Here we report the use of both nondenaturing amplification and protein-misfolding cyclic amplification (PMCA) to amplify PrP
CWD
in vitro. Normal brains from deer, transgenic mice expressing cervid PrP
C
[Tg(cerPrP)1536 mice], and ferrets supported amplification. PMCA using normal Tg(cerPrP)1536 brains as the PrP
C
substrate produced >6.5 × 10
9
-fold amplification after six rounds. Highly efficient in vitro amplification of PrP
CWD
is a significant step toward detection of PrP
CWD
in the body fluids or excreta of CWD-susceptible species.
Phenotypic and Functional Changes of Cytotoxic CD56posNatural T Cells Determine Outcome of Acute Hepatitis C Virus Infection
Authors: Golden-Mason Lucy , Castelblanco Nicole , O'Farrelly Cliona , Rosen Hugo R.
Published: June 2007

Innate CD56posnatural killer (NK) and natural T (NT) cells comprise important hepatic antiviral effector lymphocytes whose activity is fine-tuned through surface NK receptors (NKRs). Dysregulation of NKRs in patients with long-standing hepatitis C virus (HCV) infection has been shown, but little is known regarding NKRs in acute infection. Treatment-naïve patients with acute HCV (n= 22), including 10 with spontaneous recovery, were prospectively studied. CD56posNT levels were reduced early in acute HCV infection and did not fluctuate over time. In resolving HCV infection, NT cells with a more activated phenotype (lower CD158A and higher natural cytotoxicity receptor expression) at baseline predated spontaneous recovery. Moreover, NKG2A expression on CD56+NT cells correlated directly with circulating HCV RNA levels. Deficient interleukin-13 (IL-13) production by NT cells and reduced IL-2-activated killing (LAK) at baseline were associated with the ultimate development of persistence. These results indicate a previously unappreciated role for NT cells in acute HCV infection and identify a potential target for pharmacologic manipulation.
Differential effects of strength versus power training on bone mineral density in postmenopausal women: a 2-year longitudinal study
Authors: von Stengel Simon , Kemmler Wolfgang , Kalender Willi A , Engelke Klaus , Lauber Dirk
Published: June 2007

Objectives:

To investigate the effect of two different schemes of loading in resistance training on bone mineral density (BMD) and pain in pretrained postmenopausal women.

Methods:

53 pretrained women (mean (SD) age 58.2 (3.7) years) who carried out a mixed resistance and gymnastics programme were randomly assigned to a strength training (ST) or power training (PT) group. The difference between the two groups was the movement velocity during the resistance training (ST, 4 s (concentric)/4 s (eccentric); PT, explosive/4 s). Otherwise both groups carried out periodised progressive resistance training (10–12 exercises, 2–4 sets, 4–12 repetitions at 70–92.5% of the one-repetition maximum (2/week) for 2 years. Mechanical loading was determined with a force measuring plate during the leg press exercise. At baseline and after 2 years, BMD was measured at different sites with dualx-ray absorptiometry. Pain was assessed by questionnaire.

Results:

Loading magnitude, loading/unloading rate, loading amplitude and loading frequency differed significantly (p<0.001) between the two groups. After 2 years, significant between-group differences were detected for BMD (PT, −0.3%; ST, −2.4%; p<0.05) and bone area (PT, 0.4%; ST, −0.9%; p<0.05) at the lumbar spine. At the hip, there was a non-significant trend in favour of the PT group. Also the incidence of pain indicators at the lumbar spine was more favourable in the PT group.

Conclusion:

The results show that PT may be superior for maintaining BMD in postmenopausal women. Furthermore, PT was safe as it did not lead to increased injury or pain.
THE TYPE-II SINGULAR SEE-SAW MECHANISM
Authors: MCDONALD K. L. , MCKELLAR B. H. J.
Published: June 2007

The singular see-saw mechanism is a variation of the see-saw mechanism whereby the right-chiral neutrino Majorana mass matrix is singular. Previous works employing the singular see-saw mechanism have assumed a vanishing left-chiral Majorana mass matrix. We study the neutrino spectrum obtained under a singular see-saw mechanism when the left-chiral neutrinos possess a nonzero Majorana mass matrix. We refer to this as the type-II singular see-saw mechanism. The resulting neutrino spectrum is found to be sensitive to the hierarchy of the Dirac and Majorana mass scales used and we explore the phenomenological consequences of the candidate hierarchies. The compatibility of the resulting spectra with the body of neutrino oscillation data is discussed. It is found that neutrino mass matrices with this structure result in 3+1 or 2+2 neutrino spectra, making it unlikely that this mass matrix structure is realized in nature. If the left-chiral Majorana mass matrix is also singular we show that a type-II singular see-saw mechanism can realize a spectrum of one active-sterile pseudo-Dirac neutrino in conjunction with two active Majorana neutrinos effectively decoupled from the sterile sector. This realizes a scheme discussed in the literature in relation to astrophysical neutrino fluxes.
Slicing as a program transformation
Authors: Ward Martin , Zedan Hussein
Published: June 2007

The aim of this article is to provide a unified mathematical framework for program slicing which places all slicing work for sequential programs on a sound theoretical foundation. The main advantage to a mathematical approach is that it is not tied to a particular representation. In fact the mathematics provides a sound basis for
any
particular representation. We use the WSL (wide-spectrum language) program transformation theory as our framework. Within this framework we define a new semantic relation,
semirefinement
, which lies between semantic equivalence and semantic refinement. Combining this semantic relation, a syntactic relation (called
reduction
), and WSL's remove statement, we can give mathematical definitions for backwards slicing, conditioned slicing, static and dynamic slicing, and semantic slicing as program transformations in the WSL transformation theory. A novel technique of “encoding” operational semantics within a denotational semantics allows the framework to handle “operational slicing”. The theory also enables the concept of slicing to be applied to nondeterministic programs. These transformations are implemented in the industry-strength FermaT transformation system.
Fast computation of low-rank matrix approximations
Authors: Achlioptas Dimitris , Mcsherry Frank
Published: June 2007

Given a matrix
A
, it is often desirable to find a good approximation to
A
that has low rank. We introduce a simple technique for accelerating the computation of such approximations when
A
has strong spectral features, that is, when the singular values of interest are significantly greater than those of a random matrix with size and entries similar to
A
. Our technique amounts to independently sampling and/or quantizing the entries of
A
, thus speeding up computation by reducing the number of nonzero entries and/or the length of their representation. Our analysis is based on observing that the acts of sampling and quantization can be viewed as adding a random matrix
N
to
A
, whose entries are independent random variables with zero-mean and bounded variance. Since, with high probability,
N
has very weak spectral features, we can prove that the effect of sampling and quantization nearly vanishes when a low-rank approximation to
A
+
N
is computed. We give high probability bounds on the quality of our approximation both in the Frobenius and the 2-norm.
Evaluating the accuracy of implicit feedback from clicks and query reformulations in Web search
Authors: Joachims Thorsten , Granka Laura , Pan Bing , Hembrooke Helene , Radlinski Filip , Gay Geri
Published: June 2007

This article examines the reliability of implicit feedback generated from clickthrough data and query reformulations in World Wide Web (WWW) search. Analyzing the users' decision process using eyetracking and comparing implicit feedback against manual relevance judgments, we conclude that clicks are informative but biased. While this makes the interpretation of clicks as absolute relevance judgments difficult, we show that relative preferences derived from clicks are reasonably accurate on average. We find that such relative preferences are accurate not only between results from an individual query, but across multiple sets of results within chains of query reformulations.
Soft pattern matching models for definitional question answering
Authors: Cui Hang , Kan Min-Yen , Chua Tat-Seng
Published: June 2007

We explore probabilistic lexico-syntactic pattern matching, also known as soft pattern matching, in a definitional question answering system. Most current systems use regular expression-based hard matching patterns to identify definition sentences. Such rigid surface matching often fares poorly when faced with language variations. We propose two soft matching models to address this problem: one based on bigrams and the other on the Profile Hidden Markov Model (PHMM). Both models provide a theoretically sound method to model pattern matching as a probabilistic process that generates token sequences. We demonstrate the effectiveness of the models on definition sentence retrieval for definitional question answering. We show that both models significantly outperform the state-of-the-art manually constructed hard matching patterns on recent TREC data.

A critical difference between the two models is that the PHMM has a more complex topology. We experimentally show that the PHMM can handle language variations more effectively but requires more training data to converge.

While we evaluate soft pattern models only on definitional question answering, we believe that both models are generic and can be extended to other areas where lexico-syntactic pattern matching can be applied.
Model-based evaluation of expert cell phone menu interaction
Authors: Amant Robert St. , Horton Thomas E. , Ritter Frank E.
Published: June 2007

We describe concepts to support the analysis of cell phone menu hierarchies, based on cognitive models of users and easy-to-use optimization techniques. We present an empirical study of user performance on five simple tasks of menu traversal on an example cell phone. Two of the models applied to these tasks, based on GOMS and ACT-R, give good predictions of behavior. We use the empirically supported models to create an effective evaluation and improvement process for menu hierarchies. Our work makes three main contributions: a novel and timely study of a new, very common HCI task; new versions of existing models for accurately predicting performance; and a search procedure to generate menu hierarchies that reduce traversal time, in simulation studies, by about a third.