Investigation of the Ti/MgCl2 interface on a Si(111) 7 × 7 substrate

Photoelectron spectroscopy with synchrotron radiation, low energy electron diffraction, and ion-scattering spectroscopy were used in order to study the Ti/MgCl(2) interface grown on an atomically clean Si(111) 7 × 7 substrate. A series of high resolution spectra after deposition of a thick MgCl(2) layer, step by step deposition of Ti and gradual annealing, indicated a very reactive interface even at room temperature. Strong interaction between the incoming Ti atoms and the MgCl(2) layer, leads to the formation of Ti(2+) and Ti(4+) oxidation states. The interfacial interaction continues even at multilayer Ti coverage mainly by the partial disruption of Mg-Cl bonds and the formation of Ti-Cl sites, rendering this interface a very promising UHV-compatible model of a pre-catalyst for olefin polymerization. After the final annealing, the MgCl(2) multilayers desorb while Ti remains on the surface forming a silicide layer on which Cl and Mg atoms are attached.

MIMO-OFDM WDM PON with DM-VCSEL for femtocells application

We report on experimental demonstration of 2x2 MIMO-OFDM 5.6-GHz radio over fiber signaling over 20 km WDM-PON with directly modulated (DM) VCSELs for femtocells application. MIMO-OFDM algorithms effectively compensate for impairments in the wireless link. Error-free signal demodulation of 64 subcarrier 4-QAM signals modulated at 198.5 Mb/s net data rate is achieved after fiber and 2 m indoor wireless transmission. We report BER of 7x10(-3) at the receiver for 16-QAM signals modulated at 397 Mb/s after 1 m of wireless transmission. Performance dependence on different wireless transmission path lengths, antenna separation, and number of subcarriers have been investigated.

The interfacial properties of MgCl(2) thin films grown on Ti(0001)

Photoelectron spectroscopy with synchrotron radiation (SRPES), temperature programmed desorption (TPD), low energy electron diffraction (LEED), and ion-scattering spectroscopy (ISS) were used in order to study the MgCl(2)/Ti(0001) interface. A clear hexagonal LEED pattern confirmed the presence of a quite large grain of Ti(0001) on the substrate while no new superstructure was formed after deposition of MgCl(2) either at room or at elevated temperatures. A series of high resolution spectra after step by step MgCl(2) deposition and gradual annealing indicated strong interaction between MgCl(2) and the substrate while ISS measurements showed that there is no migration of Ti atoms into the deposit layers. Additional quantities of deposited MgCl(2) grew stoichimetrically on top of the chemically active interface. Annealing at approximately 350 degrees C caused clustering of the MgCl(2) multilayer and TPD results showed that they desorbed stoichimetrically at temperatures between 360 and 380 degrees C. The interfacial TiCl(x)Mg(y) species dissociated by the disruption of the Cl-Mg bonds at temperatures higher than 400 degrees C and metallic Mg evaporated. The Cl atoms remained attached on the Ti surface but they did not form any ordered structure even after annealing at 730 degrees C. The present results indicate the occurrence of charge transfer at the Ti/MgCl(2) interface through the Cl ligands and provide valuable information for catalyst design.

Strategic planning in medical education: enhancing the learning environment for students in clinical settings

BACKGROUND

The 1999 Cambridge Conference was held in Northern Queensland, Australia, on the theme of clinical teaching and learning. It provided an opportunity for groups of academic medical educators to consider some of the challenges posed by recent changes to health care delivery and medical education across a number of countries.

PURPOSE

This paper describes the issues raised by the practical challenges posed by the current environment and how they might be addressed in ways that could promote more effective learning in clinical settings.

METHOD

A SWOT analysis is a tool that can help in forward planning by identifying the strengths, weaknesses, opportunities and threats presented by any situation. Our SWOT analysis was used to generate a list of items, from which we chose those most feasible and most likely to promote positive change.

RESULTS

Twenty different issues were identified, with four of them chosen by consensus for further elaboration. The discussion gave rise to four main recommended strategies: ensuring that clinical teachers thoroughly understand the purpose and process of learning in clinical settings; equipping learners with 'survival skills'; making the best use of learning resources within different clinical environments and making judicious use of information technology to enhance learning efficiency.

CONCLUSIONS

The four strategies were selected not only because of their inherent importance, but also because of their feasibility. Modest changes can motivate students to feel part of a clinical team and a 'community of practice' and enhance their capacity for self-regulated practice.

A review of the evaluation of clinical teaching: new perspectives and challenges

PURPOSE

This article discusses the importance of the process of evaluation of clinical teaching for the individual teacher and for the programme. Measurement principles, including validity, reliability, efficiency and feasibility, and methods to evaluate clinical teaching are reviewed.

CONTEXT

Evaluation is usually carried out from the perspective of the learner. This article broadens the evaluation to include the perspectives of the teacher, the patient and the institutional administrators and payers in the health care system and recommends evaluation strategies.

RESULTS

Each perspective provides specific feedback on factors or attributes of the clinical teacher's performance in the domains of medical expert, professional, scholar, communicator, collaborator, patient advocate and manager. Teachers should be evaluated in all domains relevant to their teaching objectives; these include knowledge, clinical competence, teaching effectiveness and professional attributes.

CONCLUSIONS AND IMPLICATIONS

Using this model of evaluation, a connection can be made between teaching and learning about all the expected roles of a physician. This can form the basis for systematic investigation into the relationship between the quality of teaching and the desired outcomes, the improvement of student learning and the achievement of better health care practice. It is suggested that the extent of effort and resources devoted to evaluation should be commensurate with the value assigned to the evaluation process and its outcomes.

Needleless i.v. therapy: comparing three systems for safety

Three needleless systems were compared for general usability and cost. A closed, one-piece, nonmechanical unit was chosen as it proved safe in both peripheral and central lines, required minimal inservicing and yielded significant cost savings.

Anterior neopharyngeal diverticulum following laryngectomy

While less common than stricture, recurrent neoplasm, and neuromuscular dysfunction, neopharyngeal diverticulum must be considered in the differential diagnosis of postlaryngectomy dysphagia. Symptoms of difficulty clearing the neopharynx during and after a swallow, with regurgitation of undigested material, should alert the clinician to this possibility. Experience with 3 postlaryngectomy patients with anterior neopharyngeal divericulae serve as the springboard for discussion of the clinical spectrum, radiologic features, contributory pathophysiologic factors, and therapeutic options concerning this condition. Surgical indications, approaches, and potential hazards are reviewed.

Trauma and forensic medicine

Trauma physicians are frequently involved in the evaluation and treatment of patients who are victims of crimes or themselves criminals. These physicians usually have little or no training in the forensic aspects of emergency medical care and therefore necessary evidence may often be overlooked, lost, inadvertently discarded, or its admissibility denied because of improper handling or documentation. Criteria were developed to evaluate the forensic medical aspects of such trauma cases and to discern the magnitude of the problem. The majority of the cases reviewed demonstrated significant forensic medical deficiencies primarily in the areas of documentation and/or handling or securing of evidence. Trauma physicians have the responsibility and potential liability to insure that necessary evidence is properly secured and preserved while caring for their patients. Educational programs should be developed for this purpose.

The effect of six months of daily treatment with the beta-2 agonist oral pirbuterol on pulmonary hemodynamics in patients with chronic hypoxic cor pulmonale receiving long-term oxygen therapy

We studied the acute and long-term effect of the oral beta-2 agonist pirbuterol on pulmonary hemodynamics and right and left ventricular ejection fractions in 11 patients with stable hypoxic chronic bronchitis and emphysema who were maintained on long-term oxygen therapy. We have used a double-blind study with random allocation of patients to receive either pirbuterol or an identical-appearing placebo. Six patients received 15 mg pirbuterol thrice daily, and five patients received a similar placebo thrice daily, over a 6-month period. The first 15-mg dose of pirbuterol by mouth at the beginning of the study raised the heart rate from 84 +/- 13 to 100 +/- 16 beats/min (mean +/- SD) (p less than 0.01), and cardiac output from 5.2 +/- 0.9 to 6.4 +/- 0.8 L/min (p less than 0.01) and right ventricular ejection fraction (RVEF) from 0.28 +/- 0.10 to 0.33 +/- 0.12 (p less than 0.01) within 120 min after receiving the drug, but without significant change in the mean pulmonary arterial pressure. None of these variables changed significantly after an acute dose of placebo in another four patients. Repeated measurements after 6 months of chronic oral therapy with either pirbuterol or placebo showed that 16 h after the last 15-mg oral dose of pirbuterol or placebo, the heart rate, mean pulmonary arterial pressure, cardiac output, total pulmonary vascular resistance, and RVEF were all not significantly different from the values 6 months previously, before receiving either pirbuterol or the placebo.(ABSTRACT TRUNCATED AT 250 WORDS)