Nanostructuring of Laser-Deposited Ti Films by Self-Limited Oxidation

Local laser-induced oxidation of thin titanium films on glass is shown to be self-limiting due to a decrease in the absorptivity during the reaction. Taking advantage of this confinement, stable writing of transparent oxide line structures narrower than the diffraction-limited focused spot of a continuous wave Ar ion laser (500 nm) has been accomplished. The greatest optical contrast (1:10) with the highest resolution down to 165 nm was observed if the film thickness is of the order of the light absorption length in the metal.     

Simulation-Based Design of a Rotatory SMA Drive

The design and optimization of a rotatory drive powered by shape memory alloy (SMA) actuators is described in this paper. SMA actuators used in technical applications are parameterized by the use of trial-and-error methods, because there is a lack of computer-aided design tools for this active material. A numerical modeling approach was developed to design and optimize the geometry and the load and heating conditions of SMA actuators in a technical system to achieve a good dynamic and a high reliability. The shape memory effect used in most technical systems is the extrinsic two way effect (2WE). This effect can be simulated with the numerical model which was implemented in MATLAB/SIMULINK. The focus of the model is on the activation behavior of the SMA actuator, which defines its rate of heating and cooling. Different load conditions and various actuator geometries and shapes, e.g. wire or spring actuator, are simulated by the calculation of the energetic balance of the whole system. The numerical model can be used to simulate time variant heating currents in order to obtain an optimal system performance. The model was used to design a rotatory SMA-drive system, which is based on the moving concept of a wave drive gear set. In contrast to the conventional system, which is driven by an electric motor, the SMA drive consists of a strain wave gear and SMA wire actuators that are applied circularly to generate a rotatory movement. Special characteristics of this drive system are a high torque density and a high positioning accuracy.     

Frontal eye field neurons orthodromically activated from the superior colliculus

Frontal eye field neurons orthodromically activated from the superior colliculus. J. Neurophysiol. 80: 3331-3333, 1998. Anatomical studies have shown that the frontal eye field (FEF) and superior colliculus (SC) of monkeys are reciprocally connected, and a physiological study described the signals sent from the FEF to the SC. Nothing is known, however, about the signals sent from the SC to the FEF. We physiologically identified and characterized FEF neurons that are likely to receive input from the SC. Fifty-two FEF neurons were found that were orthodromically activated by electrical stimulation of the intermediate or deeper layers of the SC. All the neurons that we tested (n = 34) discharged in response to visual stimulation. One-half also discharged when saccadic eye movements were made. This provides the first direct evidence that the ascending pathway from SC to FEF might carry visual- and saccade-related signals. Our findings support a hypothesis that the SC and the FEF interact bidirectionally during the events leading up to saccade generation.     

Effect of the timing of treatment of port-wine stains with the flash-lamp-pumped pulsed-dye laser

BACKGROUND: Port-wine stains can be treated with a flash-lamp-pumped pulsed-dye laser, but it is uncertain whether this treatment is more effective if administered early in life, when the skin is thinner and the lesion is smaller. METHODS: We prospectively studied 100 patients with a previously untreated port-wine stain of the head or neck. They were treated with the flash-lamp-pumped pulsed-dye laser and divided into four age groups (0 to 5, 6 to 11, 12 to 17, and 18 to 31 years). The outcome measure was lightening of the port-wine stain (reduction in the difference in color between the skin with the stain and contralateral healthy skin) as measured with a colorimeter after an average of five treatments (range, three to seven) of the entire lesion. RESULTS: Of the 100 patients, 11 could not be included in the analysis because they had received fewer than three or more than seven treatments, had an erroneous base-line color measurement, or were lost to follow-up. The sizes, locations, and colors of the port-wine stains were similar among the groups. When all 89 patients were analyzed together, the average reduction in the difference in color between the skin with the port-wine stain and contralateral healthy skin was 40 percent. The differences between age groups in the average reduction in color differences were not significant (P= 0.26). By the end of the study, only 7 of 89 patients had completed laser therapy, and in no case was clearance complete. Treatment was discontinued in all seven because the last three treatments did not lead to further lightening. CONCLUSIONS: We found no evidence that treatment of port-wine stains with the flash-lamp-pumped pulsed-dye laser in early childhood is more effective than treatment at a later age.     

Strong preference for non-invasive prenatal diagnosis in women pregnant through intracytoplasmic sperm injection (ICSI)

Intracytoplasmic sperm injection (ICSI) is a new and most powerful technique to treat severe forms of human infertility. While the follow-up studies have not shown an increased malformation risk so far, the genetic implications of ICSI are still not fully understood. For this reason, many institutions routinely recommend or even enforce invasive prenatal tests after successful intracytoplasmic sperm injection. We have counselled 107 women pregnant through ICSI about prenatal diagnosis. Sixty-five had already received genetic counselling prior to the treatment (group 1), while 42 had not attended our clinic before (group 2). They were free to choose between invasive and non-invasive diagnosis or no prenatal tests at all. Fifty-four per cent of these patients had an indication for prenatal karyotyping or other invasive procedures independent of ICSI. Only 17 per cent of the total cohort made use of amniocentesis or fetal blood sampling, 82 per cent opted for non-invasive tests (ultrasound, serum screening), and one couple did not wish any prenatal studies. The preference for non-invasive procedures was stronger in group 1 (94 per cent) than in group 2 (65 per cent). We suggest that if patients pregnant through ICSI have the option to choose freely between invasive and non-invasive prenatal tests, they strongly favour the latter.     

Seminal plasma PSA in spinal cord injured men: a preliminary report

We report the case of a 48-year-old patient who developed acute onset bilateral, peripheral motor dysfunction in the arms and forearms. Clinical history, electromyography and laboratory tests confirmed the diagnosis of peripheral neuropathy caused by lead poisoning from the domestic water supply. The EMG showed axonal alterations. Improvement was observed after treatments with chelating agents and removal of the source of poisoning. This case provides the opportunity to recall the traditional 1889 Dejerine classification of lead-related peripheral neuropathies and is a warning signal that lead poisoning remains a problem in peri-urban areas of developed countries.     

Decrease in ventilation time with a standardized weaning process

OBJECTIVE: To test the hypothesis that standardizing the process of weaning from mechanical ventilation would decrease ventilation times and length of stay in a surgical intensive care unit. DESIGN: Comparison of historic ventilation times with physician-directed weaning with those obtained with protocol-guided weaning by respiratory therapists. SETTING: Urban, teaching surgical intensive care unit with open admission policy and no dominant diagnosis related group. RESULTS: From January 1, 1995, through December 31, 1995, 378 patients who underwent physician-directed weaning from a ventilator had 64488 hours of ventilation, compared with 57796 ventilation hours in 515 patients with protocol-guided weaning (April 1, 1996, through May 31, 1997). The mean hours of ventilation decreased by 58 hours, a 46% decrease (P<.001). The length of hospital stay decreased by 1.77 days (29% change), while the Acute Physiology and Chronic Health Evaluation III score remained at 50 to 51. The number of reintubations did not change. The marginal cost savings was $603580. CONCLUSION: Protocol-guided weaning from mechanical ventilation leads to more rapid extubation than physician-directed weaning and has great potential for cost savings.