Uniform texture synthesis and texture mapping using global parameterization

Texture mapping and texture synthesis are two popular methods for the decoration of surfaces with visual detail. Here, an existing challenge is to preserve, or at least balance, two competing metrics: scale and angle. In this paper we present two methods for this, both based on global conformal parameterization. First, we describe a texture synthesis algorithm for surfaces with arbitrary topology. By using the conformal parameterization, the 3D surface texture synthesis problem can be converted to a 2D image synthesis problem, which is more intuitive, easier, and conceptually simpler. While the conformality of the parameterization naturally preserves the angles of the texture, in this paper we provide a multi-scale technique to also maintain a more uniform area scaling factor. A second novel contribution is to employ the global parameterization to simultaneously preserve orthogonality and size in texture mapping. For this, we show that a conformal factor-driven mass-spring method offers a convenient way to trade off these two qualitative metrics. Our algorithms are simple, efficient and automatic, and they are theoretically sound and universal to general surfaces as well.     

A multikey secure multimedia proxy using asymmetric reversible parametric sequences: theory, design, and implementation

Because of limited server and network capacities for streaming applications, multimedia proxies are commonly used to cache multimedia objects such that, by accessing nearby proxies, clients can enjoy a smaller start-up latency and receive a better quality-of-service (QoS) guarantee-for example, reduced packet loss and delay jitters for their requests. However, the use of multimedia proxies increases the risk that multimedia data are exposed to unauthorized access by intruders. In this paper, we present a framework for implementing a secure multimedia proxy system for audio and video streaming applications. The framework employs a notion of asymmetric reversible parametric sequence (ARPS) to provide the following security properties: i) data confidentiality during transmission, ii) end-to-end data confidentiality, iii) data confidentiality against proxy intruders, and iv) data confidentiality against member collusion. Our framework is grounded on a multikey RSA technique such that system resilience against attacks is provably strong given standard computability assumptions. One important feature of our proposed scheme is that clients only need to perform a single decryption operation to recover the original data even though the data packets may have been encrypted by multiple proxies along the delivery path. We also propose the use of a set of encryption configuration parameters (ECP) to trade off proxy encryption throughput against the presentation quality of audio/video obtained by unauthorized parties. Implementation results show that we can simultaneously achieve high encryption throughput and extremely low video quality (in terms of peak signal-to-noise ratio and visual quality of decoded video frames) for unauthorized access.     

Statistical techniques for analyzing data from prevention trials: Treatment of no-shows using Rubin's causal model.

Noncompliance is a common challenge in the analysis and interpretation of prevention trials. The authors describe new formulations of the problem based on D. B. Rubin's (1974, 1978) causal model. The formulations help clarify assumptions underlying estimation procedures and yield more efficient methods of estimation. The authors apply the methods to a trial of a job training intervention in which nearly half the participants randomly assigned to the intervention failed to attend the job training seminars. An interesting feature is the presence of covariates measured prior to treatment randomization. Versions of the model that condition on these covariates suggest positive results for the intervention in a high-risk group but no evidence of gains in a low-risk group. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Survival after surgical treatment for primary hyperparathyroidism

BACKGROUND: Reports have suggested that patients with primary hyperparathyroidism (pHPT) are at increased risk for premature death, even when they reach normocalcemia. This study addresses factors that may be of relevance for long-term outcome. METHODS: Between 1980 and 1984, 1052 patients (27% men and 73% women; median age, 59 years) underwent initial cervical exploration for pHPT. Long-term follow-up was obtained with regard to overall survival and cause of death. By using univariate and multivariate (Cox) survival analysis, subgroups of patients were compared. RESULTS: Median follow-up was 12 years (range, 0 to 15 years). Overall, survival was not decreased compared with the expected survival of a gender- and age-matched midwest population. Survival was better in patients with a history of kidney stones (p = 0.044), without osteoporosis (p = 0.004), and without muscle weakness (p = 0.013). CONCLUSIONS: Decreased long-term survival was not evident in this study. Age at the time of initial surgical treatment and the degree of endocrine activity of the diseased glands appear to be the most important independent prognostic factors for survival. Comparison of these data to prior Scandinavian data is not justified, principally because of the less advanced stage of disease in this study.     

GPC data interpretation

A rigorous procedure for reducing gel permeation chromatography elution data to differential molecular weight distribution curves is discussed and demonstrated by two sample calculations. The errors introduced by failure to correct the ordinates of the elution curve by means of a differential calibration curve are identified, and a simple graphical conversion procedure is illustrated.     

An experimental reactor for kinetic studies: continuously-fed batch reactor

The use of a continuously-fed batch reacter (CFBR) as an experimental tool for the kinetic studies is presented for liquid- and gas-phase reactions, and noncatalytic gas-solid reactions. An experimental CFBR run is demonstrated using the reaction involving sucrose conversion to substantiate the theoretical results. The concept used for the CFBR is the fact that at an extremum of concentration the rate of concentration change is zero. For the liquid- and gas-phase reactions, the CFBR can be used as an alternative to the CSTR. For slow reactions, the rate determined from a CFBR run is more accurate than the rate determined from a CSTR run. Determination of the rates over the entire conversion range is made easy for fast reactions with the use of the CFBR. Results are extended to noncatalytic gas-solid reactions. It is shown that the fractional change of reacting surface area of the solid reactant can be obtained using the CFBR under the limiting condition of negligible effect of mass transfer.     

On using a communication-mapping model for environmental management (CMEM) to improve environmental performance in project development processes

This paper examines the existing environmental management communications practice among project participants in project development processes. There is a growing pressure for all project participants to extend their traditional business objectives of only lowering cost and shortening project duration to improve environmental performance. In achieving better environmental performance, it is essential to collect responses from project participants including project clients, consultants, contractors and various sub-contractors to build up collaboration. As this collaboration is based largely on communications among various parties, the validity and effectiveness of the communications are essential to enable effective collaboration. By investigating practical applications, this paper identifies gaps of communications among project participants, and shows that these gaps present barriers to the improvement of environmental performance in construction. Possible solutions to communication gaps are investigated, leading to the proposal of a communication-mapping model for environmental management (CMEM). The CMEM is proposed as a method aimed at effectively implementing environmental management in construction practice. Data used for this study are collected from six construction projects in Hong Kong. A free-flow mapping approach is also employed to assist the investigations. It is believed that this study can help improving communications among project participants and environmental performance in the construction industry.     

An experience of teaching for learning by observation: Remote-controlled experiments on electrical circuits

In order to facilitate senior primary school students in Hong Kong to engage in learning by observation of the phenomena related to electrical circuits, a design of a specific courseware system, of which the interactive human–machine interface was created with the use of an open-source software called the LabVNC, for conducting online remote-controlled experiments was developed in this study. The statistically significant results of a pre-test–post-test evaluation study showed that the LabVNC-based system has potential to promote students to learn the target topic under the approach of learning by observation. The assertion of the teacher on the pedagogical value of the remote-controlled experimentation and the enthusiasm of students in using the LabVNC-based system reveal the potential to integrate the use of the LabVNC-based system with the practice of scientific experiments. Based on the feedback from the teacher and students, the existing LabVNC-based system will be refined under the design-based research approach.     

Tungsten doped chromium nitride coatings

Chromium tungsten nitride films were deposited using magnetron sputtering with ion beam assistance. The content of the films was controlled through the power supplied to the chromium and tungsten targets. Results indicate that the tungsten atoms incorporated into chromium nitride films and formed the chromium tungsten nitride solid solution phase. Moreover, results of this study provide further insight into how various concentrations of tungsten affect the lattice constant, preferred orientation, crystallite size, surface morphology, hardness, internal stress, and adhesion of the films.     

X-ray Powder Diffraction Structural Phase-Transition Study of La(Cr1-xMnx)O3 (x = 0 to 0.25) Using the Rietveld Method of Analysis

The La(Cr_1-xMn_x)O₃ (x = 0 to 0.25) system exhibited a displacive phase transformation from an orthorhombic to a rhombohedral structure at temperatures ranging from about 256°C at x = 0 to 305°C at x = 0.25. The Rietveld method of X-ray analysis was used to determine structural characteristics and to assay phase concentrations when multiple phases were present. Indications were that the Mn ions on the B site affected the transition temperature through an ionic size effect; i.e., Mn³⁺, with a larger ionic size than Cr³⁺, increased the transition temperature while the presence of the smaller Mn⁴⁺ ions reduced it. A hysteresis was also observed with respect to the phase transformation as a function of temperature. The phase transformation was associated with a change in the rotation of the oxygen octahedra from an antiphase to an in-phase tilt sequence.