Interpolation of rotation and motion

In Cosserat solids such as shear deformable beams and shells, the displacement and rotation fields are independent. The finite element implementation of these structural components within the framework of flexible multibody dynamics requires the interpolation of rotation and motion fields. In general, the interpolation process does not preserve fundamental properties of the interpolated field. For instance, interpolation of an orthogonal rotation tensor does not yield an orthogonal tensor, and furthermore, does not preserve the tensorial nature of the rotation field. Consequently, many researchers have been reluctant to apply the classical interpolation tools used in finite element procedures to interpolate these fields. This paper presents a systematic study of interpolation algorithms for rotation and motion. All the algorithms presented here preserve the fundamental properties of the interpolated rotation and motion fields, and furthermore, preserve their tensorial nature. It is also shown that the interpolation of rotation and motion is as accurate as the interpolation of displacement, a widely accepted tool in the finite element method. The algorithms presented in this paper provide interpolation tools for rotation and motion that are accurate, easy to implement, and physically meaningful.     

Shape‐Memory Topographies on Nickel–Titanium Alloys Trained by Embossing and Pulse Electrochemical Machining

The two‐way shape‐memory effect (TWSME) in Nickel–titanium (NiTi) alloys is of interest for applications in aerospace, biomedicine, and microengineering due to its reversible shape recovery. In this study, the authors demonstrate two approaches to obtain switchable surface structures using the TWSME. Samples are structured using two surface geometries by either cold embossing, or pulse electrochemical machining (PECM). After planarization, a change from optically smooth to structured and vice versa is observed. The switch is induced through heating and cooling the sample above and below the phase transformation temperature. The protrusions reflect the pattern applied by the two processes. Both methods are promising for preparation of switchable metallic surfaces on larger areas.     

Solution homopolymerizations of n-butyl acrylate and styrene mediated using 2,2,5-trimethyl-4-tert-butyl-3-azahexane-3-oxyl (TITNO)

Use of Styryl-TITNO (the styrene alkoxyamine of 2,2,5-trimethyl-4-tert-butyl-3-azahexane-3-oxyl) as mediator for nitroxide-mediated polymerization (NMP) of n-butyl acrylate (BA) and styrene has been investigated at temperatures ≤110 °C. Very good control of molecular weight and molecular weight dispersity with no measurable loss of active chains, and no evidence of tails in the molecular weight distribution as conversion increases, was observed at 90 °C for BA and at 70 °C for styrene. The alkoxyamine dissociation equilibrium constant values determined for polyBA-TITNO (8.5 × 10⁻¹¹ mol L⁻¹ at 90 °C) and polystyrene-TITNO (3.1 × 10⁻⁹ mol L⁻¹ at 70 °C) are consistent with those required for control when using more established nitroxides that require higher temperatures to achieve these values. The lower optimum polymerization temperatures with Styryl-TITNO as mediator provide new opportunities for NMP and are especially significant for styrene since this appears to eliminate completely the complications from thermal initiation.     

Complementation of rational sets on scattered linear orderings of finite rank

In a preceding paper [V. Bruyère, O. Carton, Automata on linear orderings, in: J. Sgall, A. Pultr, P. Kolman (Eds.), MFCS’2001, in: Lect. Notes in Comput. Sci., vol. 2136, 2001, pp. 236–247. iGM report 2001-12], automata have been introduced for words indexed by linear orderings. These automata are a generalization of automata for finite, infinite, bi-infinite, and even transfinite words studied by Büchi. Kleene’s theorem has been generalized to these words. We show that deterministic automata do not have the same expressive power. Despite this negative result, we prove that rational sets of words of finite ranks are closed under complementation.     

An analytical two-temperature model for convection-diffusion in multilayered systems: Application to the thermal characterization of microchannel reactors

The main purpose of this paper is to implement some convenient analytical solutions of the two-dimensional convection-diffusion equations in a multilayered system, in the form of some relationships between average temperature fields, based on the thermal quadrupole formalism. Some equivalent analogical networks are proposed in order to implement the model in a more convenient form, based on the electrical analogy. The important advantage of such approach is to connect different layers through simple network connections between the respective interface variables. Special emphasis is laid on the case where the lateral boundary conditions correspond to insulated walls. The transient case is also presented, for non-insulated lateral boundary conditions, coupled with a third layer. Some examples are given in order to illustrate the suitability of the proposed model in the case of temperature field image processing in a microfluidic chip.     

Premature ejaculation and serotonergic antidepressants-induced delayed ejaculation: the involvement of the serotonergic system

OBJECTIVE: To analyze the causes of therapeutic success and failure in the management of patients with high-risk gestational trophoblastic tumors (GTTs). STUDY DESIGN: Analysis of 272 consecutive high-risk patients treated at the trophoblastic disease center at the Charing Cross Hospital between 1979 and 1995. RESULTS: EMA (etoposide, methotrexate, actinomycin D)/CO (cyclophosphamide, vincristine) chemotherapy is our treatment of choice for patients with high-risk GTT. In 272 consecutive patients the cumulative five-year survival was 86.2% (95% confidence interval, 81.9-90.5%). No deaths occurred from GTT more than two years after the start of treatment. In patients whose disease became resistant to EMA/CO or relapsed after receiving EMA/CO, the majority (70%) could be salvaged with further chemotherapy (usually with the EP (etoposide, cisplatin)/EMA chemotherapy with or without surgery. Multivariate analysis identified the following adverse prognostic factors: presence of liver metastases (P < .0001), prolonged interval from antecedent pregnancy (P < .0001), presence of brain metastases (P = .0008) and term delivery of antecedent pregnancy (P = .045). Intensive chemotherapy for treating high-risk GTT carries a small risk of inducing second malignancies, and two patients developed acute myeloid leukemia, 2 cervical malignancy and 1 gastric adenocarcinoma after receiving EMA/CO chemotherapy. CONCLUSION: EMA/CO is an effective and well-tolerated regimen for high-risk GTT. Salvage chemotherapy with EP/EMA is effective in the majority of patients whose disease is resistant to EMA/CO and should be combined with surgery when the dominant site of resistant disease is known. Major adverse prognostic variables have been identified, and patients with combinations of these factors should be considered for innovative therapeutic approaches from the outset.     

Stress-induced hyperthermia in mice: a methodological study

When the rectal temperature of group-housed mice is measured sequentially, the temperature of the last measured mouse is higher than that of the first mouse. This phenomenon is called stress-induced hyperthermia (SIH). We varied several experimental parameters to elucidate the mechanism behind this SIH. SIH was stable and found by all technicians performing the experiments. The large intertechnician difference in the mean rectal temperature could be eliminated by training in an identical fixation and handling technique. SIH was both independent of the number of handling days preceding the experiment and of the number of disturbances (0, 1, 2, or 5) implied on the mice per minute. The percentage of hyperthermic mice in 10-mice cages increased when the time interval between the individual measurements increased from 1 to 2, 5 or 10 min. In all groups the maximum increase was reached after an interval of approximately 10 min. SIH of mouse 10 returned time dependently in approximately 60 min to basal temperature. When SIH was tested on 2 or 5 successive days no tolerance developed. When animals were reused after 7 or 14 days SIH did not differ from day 1, implying that animals can be reused. When the number of mice was decreased from 10 to 5 mice per cage, the SIH of vehicle-treated mice was slightly lower in 5-mice cages compared to 10-mice cages. The blocking effects on SIH by anxiolytics was also less clear in 5-mice cages compared to 10-mice cages.(ABSTRACT TRUNCATED AT 250 WORDS)     

Analysis of multiport rectangular waveguide devices using pulsed finite-difference time-domain (FDTD) technique

The pulsed FDTD method is used to analyse multiport junctions in rectangular waveguides. Two representative examples are considered, namely the H-plane tee junction and the folded H-plane tee junction. Computed results for the scattering parameters are compared to measurements performed by the authors.<>