Effect of cooling rate on Ti–Cu eutectoid alloy microstructure

Titanium alloys present a combination of properties that makes them suitable materials for various medical applications, and there is special interest in Ti–Cu alloys for the fabrication of dental prostheses. The addition of Cu to Ti lowers the melting point of the alloy, as well as leading to the development of desirable mechanical properties. In this study a eutectoid alloy was prepared and heat treated, then cooled at various cooling rates. The eutectoid structure (α + Ti₂Cu) was observed for all cooling rates used, and evidence of α′ martensite was found for cooling rate higher than 9 °C s^–1. Lower cooling rates resulted in higher modulus values. This was attributed to the volume fraction of the α and Ti₂Cu phases. Higher cooling rates produced structures with lower modulus values and greater hardness, a result attributed mainly to the development of a martensitic structure.     

Eating behavior in response to food-cue exposure: Examining the cue-reactivity and counteractive-control models.

Many studies have demonstrated that those high in weight-related concerns eat more after food-cue exposure, which is consistent with predictions of the cue-reactivity model. However, the counteractive-control model predicts that exposure to fattening foods activates dieting-related goals and behavior in weight-concerned individuals. Although these models seem incongruous, the authors hypothesized that the salience of the cue could represent a critical factor in determining which model is activated. The authors predicted that attending to salient food cues would result in increased intake (cue reactivity) in individuals with high weight-related concerns, whereas incidental food-cue exposure would result in decreased intake (counteractive control), relative to control exposure. The authors employed a 3 (attended vs. incidental vs. control cue) × 2 (low vs. high weight-related concerns) design. As expected, participants with high weight-related concerns who attended to a food cue ate more than did both those with high weight-related concerns in the control condition and those with low weight-related concerns in the attended-cue condition; however, intake of individuals with high weight-related concerns who were exposed to the incidental cue did not differ from that of those in the control condition. The manner of food-cue presentation may be a critical factor in determining eating behavior. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Path-following control of mobile robots in presence of uncertainties

This paper presents, in detail, the implementation of a new control strategy, Kalman-based active observer controller (AOB), for the path following of wheeled mobile robots (WMRs) subject to nonholonomic constraints. This control strategy presents some particularities as being used in discrete mode, and being robust against uncertainties and disturbances such as the ones due to the use of the input-output feedback-linearization method in discrete mode, while it was developed to be used in continuous mode. The performance of the proposed control algorithm is verified via computer simulation, and is compared with other control strategies, such as pole placement controller (PPC) and PPC with a Kalman filter observer (CKF).     

Text-independent speaker recognition based on the Hurst parameter and the multidimensional fractional Brownian motion model

In this paper, a text-independent automatic speaker recognition (ASkR) system is proposed-the SR/sub Hurst/-which employs a new speech feature and a new classifier. The statistical feature pH is a vector of Hurst (H) parameters obtained by applying a wavelet-based multidimensional estimator (M/spl I.bar/dim/spl I.bar/wavelets ) to the windowed short-time segments of speech. The proposed classifier for the speaker identification and verification tasks is based on the multidimensional fBm (fractional Brownian motion) model, denoted by M/spl I.bar/dim/spl I.bar/fBm. For a given sequence of input speech features, the speaker model is obtained from the sequence of vectors of H parameters, means, and variances of these features. The performance of the SR/sub Hurst/ was compared to those achieved with the Gaussian mixture models (GMMs), autoregressive vector (AR), and Bhattacharyya distance (dB) classifiers. The speech database-recorded from fixed and cellular phone channels-was uttered by 75 different speakers. The results have shown the superior performance of the M/spl I.bar/dim/spl I.bar/fBm classifier and that the pH feature aggregates new information on the speaker identity. In addition, the proposed classifier employs a much simpler modeling structure as compared to the GMM.     

Small-signal stability for parallel-connected inverters instand-alone AC supply systems

This paper presents a small-signal analysis for parallel-connected inverters in stand-alone AC supply systems. The control technique of the inverters is based on frequency and voltage droops, which depends on the local variable measurements and does not need control interconnections. Simulation and experimental results show that the system is well represented by the small-signal model. Some root locus plots for the system are provided, which make the stability studies and design easier     

A simple experimental arrangement for measuring the vapour pressures and sublimation enthalpies by the Knudsen effusion method: Application to DNA and RNA bases

We measured the vapour pressure of several DNA and RNA bases—uracil, adenine, guanine, thymine and cytosine—in the 300–450 K range. In each case the sample mass loss rate was measured as function of temperature with a simple setup consisting of a commercial film deposition system and a homemade oven. Afterwards vapour pressure values were extracted from these data using the Knudsen effusion method. Sublimation enthalpy values, obtained from vapour pressure data by applying the Clausius–Clapeyron equation, are in very good agreement with literature values. The results suggest that crystal-based film thickness monitors may be useful in on-line cross-section measurements, monitoring the gas target thickness. They also show the viability of using this oven for producing a biomolecular gas target.     

The molecular structure of green fluorescent protein

The crystal structure of recombinant wild-type green fluorescent protein (GFP) has been solved to a resolution of 1.9 A by multiwavelength anomalous dispersion phasing methods. The protein is in the shape of a cylinder, comprising 11 strands of beta-sheet with an alpha-helix inside and short helical segments on the ends of the cylinder. This motif, with beta-structure on the outside and alpha-helix on the inside, represents a new protein fold, which we have named the beta-can. Two protomers pack closely together to form a dimer in the crystal. The fluorophores are protected inside the cylinders, and their structures are consistent with the formation of aromatic systems made up of Tyr66 with reduction of its C alpha-C beta bond coupled with cyclization of the neighboring glycine and serine residues. The environment inside the cylinder explains the effects of many existing mutants of GFP and suggests specific side chains that could be modified to change the spectral properties of GFP. Furthermore, the identification of the dimer contacts may allow mutagenic control of the state of assembly of the protein.     

A randomized phase-II study of BB-10010 (macrophage inflammatory protein- 1alpha) in patients with advanced breast cancer receiving 5-fluorouracil, adriamycin, and cyclophosphamide chemotherapy

BB-10010 is a variant of the human form of macrophage inflammatory protein-1alpha (MIP-1alpha), which has been shown in mice to block the entry of hematopoietic stem cells into S-phase and to increase their self-renewal capacity during recovery from cytotoxic damage. Its use may constitute a novel approach for protecting the quality of the stem cell population and its capacity to regenerate after periods of cytotoxic treatment. Thirty patients with locally advanced or metastatic breast cancer were entered into the first randomized, parallel group controlled phase II study. This was designed to evaluate the potential myeloprotective effects of a 7-day regimen of BB-10010 administered to patients receiving six cycles of 5-fluorouracil (5-FU), adriamycin, and cyclophosphamide (FAC) chemotherapy. Patients were randomized, 10 receiving 100 microgram/kg BB-10010, 11 receiving 30 microgram/kg BB-10010, and nine control patients receiving no BB-10010. BB-10010 was well-tolerated in all patients with no severe adverse events related to the drug. Episodes of febrile neutropenia complicated only 4% of the treatment cycles and there was no difference in incidence between the treated and nontreated groups. Studies to assess the generation of progenitor cells in long-term bone marrow cultures were performed immediately preceding chemotherapy and at the end of six dosing cycles in 18 patients. Circulating neutrophils, platelets, CD 34(+) cells, and granulocyte/macrophage colony-forming cell (GM-CFC) levels were determined at serial time points in cycles 1, 3, and 6. The results showed similar hemoglobin and platelet kinetics in all three groups. On completion of the six treatment cycles, the average pretreatment neutrophil levels were reduced from 5.3 to 1.7 x 10(9)/L in the control patients and from 4.3 to 1.9 and 4.5 to 2.5 x 10(9)/L in the 30/100 microgram/kg BB-10010 groups, respectively. Relative to their pretreatment values, 50% of the patients receiving BB-10010 completed the treatment with neutrophil values significantly higher than any of the controls (P = .02). Mobilization of GM-CFC was enhanced by BB-10010 with an additional fivefold increase over that generated by chemotherapy alone, giving a maximal 25-fold increase over pretreatment values. Bone marrow progenitor assays before and after this standard regimen of chemotherapy indicated little long-term cumulative impairment to recovery from chemotherapy. Despite the limited cumulative damage to the bone marrow, which may have minimized the protective value of BB-10010 during this regimen of chemotherapy, better recovery of neutrophils in the later treatment cycles with BB-10010 was indicated in a number of patients.     

Helicobacter pylori in South America

Interviews of a representative sample of 201 physicians (general practitioners, gynecologists, pediatricians) with a mean age of 47 years show: there is a unmanageable amount of information about drugs and their risks. The physicians prefer practical experience rather than specialized literature. As a result they plead for a central authority of information with periodical reports on the current knowledge of drug-therapy and with the possibility of therapeutical consultation.