Determination of O and OH adsorption sites and coverage in situ on Pt electrodes from Pt L(2,3) X-ray absorption spectroscopy.

The adsorption of atomic oxygen and hydroxide on a platinum electrode in 0.1 M HClO4 or H2SO4 electrolytes was studied in situ with Pt L(2,3) X-ray absorption spectroscopy (EXAFS and XANES). The Pt L3 edge absorption data, mu, were collected at room temperature in transmission mode on beamline X-11A at the National Synchrotron Light Source using a custom built cell. The Pt electrode was formed of highly dispersed 1.5-3 nm particles supported on carbon. A novel difference procedure (delta mu = mu(O[H]/Pt) - mu(Pt)) utilizing the L3 XANES spectra at different applied voltages was used to isolate the effects of O[H] (O or OH) adsorption in the XANES spectra. The Deltamu results are compared with results obtained from real-space full-multiple scattering calculations utilizing the FEFF8 code on model clusters. The experimental results, when compared with theoretical calculations, allow the adsorption site to be identified. At low coverages OH adsorbs primarily in 1-fold coordinated atop sites. As the coverage increases, O binds in the bridge/fcc sites, and at still higher coverages above 1.05 V RHE, O adsorbs into a higher coordinated n-fold or subsurface site, which is thought to be the result of Pt-O site exchange and oxide formation. These results are similar to those found in the gas phase. Direct specific adsorption of bisulfate anions in H2SO4 is spectroscopically seen in both the EXAFS and XANES data and is seen to impede oxygen adsorption consistent with previous reports.

The isomorphic mapping hypothesis: evidence from Korean.

This paper evaluates the relative merits of the trace deletion hypothesis, which attributes agrammatic comprehension difficulties to the loss of traces, and the isomorphic mapping hypothesis, which proposes that agrammatics have difficulty understanding sentences in which there is a nonisomorphic mapping between the syntactic representation and the corresponding event in the real world. (The two are isomorphic if the order of NPs reflects the place of entities in the event's 'action chain.' Since agents act on themes and transmit them to goals, the agent-theme-goal order is isomorphic with the corresponding event but the agent-goal-theme order is not.) The two hypotheses contrast in the predictions they make concerning goal-theme and theme-goal patterns in Korean: the TDH predicts degraded performance on the theme-goal structure (which is derived from the goal-theme structure); the IMH predicts difficulties on the goal theme structure, since it is nonisomorphic. Results of a comprehension study involving four Korean Broca's aphasics provide strong support for the IMH over the TDH.

Anaphora and branching direction in Japanese.

This paper constitutes a response to Lust & Mazuka's (1989) defence of the Principal Branching Direction parameter and their critique of O'Grady, Suzuki-Wei & Cho's (1986) experiment, which purported to show that even children learning left-branching languages exhibit a preference for forward patterns of anaphora. Results of new experimental work with children learning Japanese are reported and shown to support the claim that there is a universal preference for forward patterns of anaphora in the early stages of language acquisition.

The transition from optional to required subjects.

We propose (contra Hyams, 1986) that the optional subject phenomenon in early child language arises because children have not yet acquired the morphological elements (primarily modals and tense) necessary to distinguish Subject-Taking (ST) verbs (e.g. finite verbs) from their non-Subject-Taking (NST) counterparts (e.g. infinitives). Unaware of this distinction, children are able only to observe that verbs sometimes occur with subjects and sometimes without. We show that our proposal makes a number of developmental predictions which we then test with the help of longitudinal data from three children. We conclude that: (1) There is no systematic morphological distinction between ST and NST verbs during the optional subject stage (OSS). (2) The emergence of the distinction between ST and NST verbs is gradual rather than sudden. (3) There is variation from child to child in terms of which morphologically-defined subclass of verbs is first recognized as subject-taking. (4) There is no link between the emergence of modals or contracted copulas and the end of the OSS.

Surgical treatment of acute evolving anterior myocardial infarction.

A series of 101 consecutive patients underwent coronary revascularization within a mean of 5.8 hours after anterior myocardial infarction. Forty-one patients had obstruction of the left anterior descending coronary artery (LAD), 35 had obstruction of the LAD and of the right or circumflex coronary artery and 25 had obstruction of the LAD and both the right and circumflex coronary arteries. Sixty-four patients (63%) had total occlusion of the LAD. In-hospital mortality was 2%. The total mortality during a mean follow-up of 43 months was 5%, and 90% of the patients were free of angina. Thirty-six patients had repeat coronary arteriography a mean of 13.4 months after operation. Fifty-two of 62 grafts (84%) were patent. Cardiac catheterization and immediate coronary artery bypass grafting in the first hours of anterior myocardial infarction can be done safely and may reduce in-hospital and long-term mortality.

Immediate coronary artery bypass for acute evolving myocardial infarction.

Two hundred twenty-seven consecutive patients had chest pain and electrocardiographic, coronary angiographic, ventriculographic, and retrospective enzyme changes consistent with acute evolving myocardial infarction (AEMI). These patients underwent coronary artery bypass grafting an average of less than 6 hours after the start of chest pain. The mean age was 55.8 years (range 28 to 79 years). Sex, coronary artery involvement, and preoperative and postoperative enzymes and electrocardiograms are presented. Follow-up angiocardiograms done an average of 12.7 months postoperatively revealed 99 patent primary grafts in 102 patients (94.3%). Ejection fractions were normal, unchanged, or improved in 86.3% of the patients. Two ventricular aneurysms measuring less than 2.5 cm in diameter were noted. Surgical in-hospital mortality was 1.76% and first-year mortality was 1.44%. Conventional therapy in 200 AEMI patients treated at the same hospitals resulted in an in-hospital mortality of 11.5%. Follow-up of 213 patients having coronary artery bypass grafting revealed that 14% had mild angina. AEMI interrupted by coronary artery bypass grafting early in the syndrome yields results which are superior to conventional management.

Intraaortic balloon counterpulsation with and without reperfusion for myocardial infarction shock.

Forty patients were treated for cardiogenic shock secondary to acute myocardial infarction. Twenty-one (group 1) were treated with intraaortic balloon counterpulsation and 19 (group 2) were treated with counterpulsation and coronary artery bypass grafting. The groups were similar in age, incidence of previous infarction, initial hemodynamics and coronary anatomy. The in-hospital mortality between group 1 (52.4%) and group 2 (42.1%) was not significantly different. The difference in long-term mortality between group 1 and group 2 was substantially different (71.4% vs 47.3%). The subset of group 2 (n = 12) that underwent reperfusion and counterpulsation within 16 hours from the onset of symptoms of infarction had a lower mortality (25.0%) than the subset (n = 7) that underwent operation more than 18 hours after the onset of symptoms (71.4%). The long-term mortality in the subset of group 2 patients operated on within 16 hours after the onset of infarction was significantly different from that in group 1 (25.0% vs 71.4%, p less than 0.03). The data suggest that reperfusion with counterpulsation is more effective when carried out early. Patients who develop shock more than 18 hours after the onset of symptoms of infarction appear to benefit most if treated with counterpulsation alone.