Density functional theory for the crystallization of two-dimensional dipolar colloidal alloys.

Two-dimensional mixtures of dipolar colloidal particles with different dipole moments exhibit extremely rich self-assembly behaviour and are relevant to a wide range of experimental systems, including charged and super-paramagnetic colloids at liquid interfaces. However, there is a gap in our understanding of the crystallization of these systems because existing theories such as integral equation theory and lattice sum methods can only be used to study the high temperature fluid phase and the zero-temperature crystal phase, respectively. In this paper we bridge this gap by developing a density functional theory (DFT), valid at intermediate temperatures, in order to study the crystallization of one and two-component dipolar colloidal monolayers. The theory employs a series expansion of the excess Helmholtz free energy functional, truncated at second order in the density, and taking as input highly accurate bulk fluid direct correlation functions from simulation. Although truncating the free energy at second order means that we cannot determine the freezing point accurately, our approach allows us to calculate ab initio both the density profiles of the different species and the symmetry of the final crystal structures. Our DFT predicts hexagonal crystal structures for one-component systems, and a variety of superlattice structures for two-component systems, including those with hexagonal and square symmetry, in excellent agreement with known results for these systems. The theory also provides new insights into the structure of two-component systems in the intermediate temperature regime where the small particles remain molten but the large particles are frozen on a regular lattice.

Filling a nanoporous substrate by dewetting of thin films.

Following a simple thermodynamic model, which predicts that an array of non-wettable pores can be filled by dewetting of sufficiently thin films, we use molecular dynamics to simulate the rupture of nanometre-thick liquid Au films on nanoporous substrates. Our simulations clearly exhibit spinodal dewetting and hole nucleation, and some of the metal is indeed absorbed by non-wettable pores solely as a virtue of the Laplace pressure acting on dewetted droplets and rivulet-like structures. Finally, we show that the fraction of absorbed Au can be increased through patterning of the initial film.

To die in one's prime: the story of Paul Wood.

Paul Wood, the leader of European cardiology during the mid-20th century, was internationally admired for his bedside teaching, clinical investigations, and an important textbook on cardiology. His studies, based on a unique quantitative approach to the grading and recording of clinical data, introduced cardiac physiology to the bedside, brought accuracy to the preoperative assessment of cardiac disease, and became the foundation for much of our current understanding about congenital and rheumatic heart disease and pulmonary hypertension. At the bedside, in front of a crowd of postgraduate students, registrars, and visitors, he was renowned for his showmanship and dazzling ability. His commanding personality--caustic, sarcastic, and combative--impressed many and offended some as he openly argued with himself and others to sleuth out the correct diagnosis. His 1950 textbook, Diseases of the Heart and Circulation, characterized by his lucid and personal style of writing and a fresh physiologic approach to cardiology, brought Wood worldwide recognition as the European authority on heart disease. The incessant demands to see patients, teach, and lecture, the burden of writing his third edition of the book, and his heavy smoking eventually took their toll. On July 13, 1962, at the age of 54, Paul Wood, the gale force wind of British cardiology and the inspiration and role model for many students, died quietly following a myocardial infarction. He left a legacy of great accomplishments as the transition figure between the old and modern era of cardiology.

Specific antibody responses to diphtheria/tetanus revaccination in children evaluated for immunodeficiency.

BACKGROUND: Assaying specific antibody levels against well-defined antigens such as diphtheria (D), tetanus (T), and more recently Haemophilus is used as one indicator of humoral immune reactivity when evaluating patients for immunodeficiency. The nature of the response to booster vaccine in this group of patients is not well defined. OBJECTIVE: To define the response to D/T booster vaccination in patients with nonprotective antibody levels in order to distinguish immunocompetent from immunodeficient children. METHODS: Patients between the ages of 16 months and 17 years referred for possible immunodeficiency were assessed for specific antibody levels as part of a standard immunologic evaluation. Twenty-six previously immunized patients had antibody titers less than or equal to 0.2 IU against D and/or T or another abnormal vaccine response. All of these patients received boosters of diphtheria and tetanus vaccine (D2T5). Diphtheria and tetanus antibody levels were assayed 4 weeks following booster vaccination. RESULTS: Of the twenty-six subjects, a subset of patients (6) failed to show significant elevations in specific-serum antibody titers to diphtheria and/or tetanus and were thus labeled nonresponders. These patients were retrospectively compared with their responder counterparts examining specific antibody titers pre-immunization and post-immunization, serum immunoglobulins, and clinical presentation. The groups showed no significant difference in baseline specific antibody measures but following re-immunization responders showed a 31.34-fold and 22.33-fold increase in D and T antibody levels, respectively. In contrast, nonresponders produced only a 2.62-fold to D and 6.15-fold increase to T (all group comparisons P < .05). Clinical presentation also tended to be more severe in the nonresponder group. CONCLUSIONS: These data stress the importance of specific antibody titers pre-immunization and post-immunization in the assessment of immunodeficiency states, and emphasize the different characteristics of responses between diphtheria and tetanus toxoids. The ability to achieve the minimum protective antibody level does not necessarily denote immune competence. Serum immunoglobulin levels and baseline antibody titers are insufficient for the functional assessment of the immune response. The ability to generate antibody responses following booster vaccination is a more complete measure of overall immune competence and should be considered when evaluating patients for replacement immunoglobulin therapy.

Effects of octreotide on circulating islet B cell products in endogenous hyperinsulinism.

The role of somatostatin analogues in the medical management of insulinomas is unclear. We describe an elderly patient with clinical and biochemical features of endogenous hyperinsulinism attributable to a benign islet B cell disorder whose incapacitating neuroglycopaenic symptoms responded dramatically to octreotide 50 micrograms subcutaneously at 2200 h each night. Octreotide suppressed inappropriate plasma concentrations of insulin thereby preventing fasting hypoglycaemia. Fasting concentrations of proinsulin, and 32-33 split proinsulin, as determined by two-site monoclonal antibody-based immunoradiometric assays, were also suppressed by octreotide.

The bowel, the genitourinary tract, and infective endocarditis.

Of 582 episodes of infective endocarditis 75 were attributable to organisms normally resident in the bowel and 12 others were associated with alimentary tract operations, investigations, or disease. The mean age of the 87 patients in this particular group was higher (59.7 years) than that of all the patients with infective endocarditis (51.4 years). As far as could be ascertained 41% had no pre-existing cardiac abnormality, and in a little under a half no predisposing event to initiate the illness was apparent. Where the portal of entry of the organism to the blood stream was evident it was slightly more often in the genitourinary than the alimentary tract. Bowel organisms are no less important than those associated with the teeth in causing infective endocarditis. It is suggested that in all those patients with known cardiac abnormalities and possibly in those over the age of 60 with normal hearts antibiotic cover should be considered when they undergo genitourinary or alimentary tract surgery or instrumentation.

The microbiology and pathogenesis of infective endocarditis.

Some details of 544 episodes of infective endocarditis occurring in 541 patients during 1981 and 1982 are reported. The mean age of patients was 51.6 years and there was a greater proportion of males (2:1). Of the 544 episodes 347 (63%) were due to streptococci, 19% to staphylococci, and 14% to bowel organisms. A wide variety of other organisms were responsible for a few cases, and 10% were culture negative. In 60% the portal of entry of the infection could not be ascertained: 19% were probably of dental origin: 16% arose from the alimentary, genitourinary, or respiratory tracts or from the skin or in association with drug addiction, fractures, or pregnancy; the remaining 5% were related to cardiac or other vascular surgery, cardiac catheterisation, haemodialysis, or other procedures involving the blood stream. Seventy-four (14%) of the 541 patients (mean age 59.0 years) died; the mortality was 30% in staphylococcal cases, 14% in infections due to bowel organisms, and 6% in other streptococcal infections. One hundred and seventy-one (32%) of the patients appeared to have had normal hearts before the onset of illness and another 59 (11%) had cardiac lesions not previously recognised. The aortic valve was the most common site of infection. Ninety (17%) of the patients had prosthetic valves or had undergone other cardiac surgery while 34 (6%) had had a previous episode of infective endocarditis. Nine (1.6%) episodes were not diagnosed until necropsy or operation and 34 (6.3%) required urgent valve replacement.

The teeth and infective endocarditis.

During 1981 and 1982 544 cases of infective endocarditis were investigated retrospectively by means of a questionnaire. Only 13.7% had undergone any dental procedure within three months of the onset of the illness, and in 42.5% there was no known cardiac abnormality before the onset of the disease. Furthermore, the number of cases occurring annually was about the same as or more than it was before the introduction of penicillin. The mouth and nasopharynx were the most likely sources of the commonest organism, Streptococcus viridans, and it is suggested that it is not dental extractions themselves which are of importance but good dental hygiene. In most patients with infective endocarditis the portal of entry of the organism whatever its nature cannot be identified. If this is so antibiotics are being given to only a small proportion of those at risk, and this would explain why the number of cases is much the same as it was before the introduction of penicillin. Furthermore, the large proportion of patients with no known previous cardiac abnormality adds to the difficulty of providing effective prophylaxis. The evidence suggests that antibiotic prophylaxis should still be given before dental procedures, and a schedule is appended. Much more importance should be given, however, to encouraging people to seek better routine dental care. We also believe that doctors and dentists should appreciate that the pattern of the disease has changed considerably in the past 50 years and that the information given here warrants a revised approach to the problem.

Some effects of emotion on the normal and abnormal heart.

Increased heart rate and catecholamine secretion are induced by certain emotions. Automobile driving in busy city traffic, racing driving, speaking before an audience, and parachute jumping are associated with sinus tachycardia 120-180 per minute, and increase in the plasma levels of adrenaline and/or noradrenaline. Electrocardiographic changes, chiefly ST depression, may occur in a small proportion of persons without ischemic symptoms and with normal resting tracings. Patients with clinical coronary disease, angina, and ischemic ST changes and arrhythmias may be induced by the emotional stimuli associated with car driving and public speaking; plasma catecholamine levels are increased in proportion to the intensity of the stimulus. beta-blockade reduces the tachycardia, and prevents in whole or in part the ST changes, arrhythmia and symptoms associated with emotional challenge to the heart. We would like to leave the reader with a final morsel of food for thought. Emotion may parallel exercise in its ability to accelerate the heart rate up to 180 per minute in healthy subjects, comparable to the maximum reached during physical exertion. Thus, there are good grounds to advise persons at risk not only against violent exercise but also against exposing themselves to intense emotion. At the same time, we would not advocate emotional overprotection, and we believe our ideas would be misinterpreted if healthy persons were to be deterred on the grounds of apprehension or nervousness from facing up to reasonable everyday professional or social challenges.

The use of "fresh" unstented homograft valves for replacement of the aortic valve. Analysis of 8 years' experience.

Between August, 1969 and May 1978, 679 patients underwent homograft replacement of the aortic valve. Isolated elective valve replacement was performed in 411 patients. Thirty-four patients had total aortic root replacement with reimplantation of the coronary arteries. There were 16 early deaths (3.9%) and 43 late deaths (10.5%) during a follow-up between 3 and 102 months (mean 47 months). Actuarial analysis showed 87% survival at 5 years and 81% at 8 years. Valve failure occurred in 24 patients (5.9%) owing to prolapse of one cusp in eight patients (2.0%), infective endocarditis in seven patients (1.7%), and degeneration of the valve in nine patients (2.2%). Degenerative valve failure was encountered after the fourth year with an incidence of 4.8% of patients at risk and occurred only in grafts from donors over the age of 65 years. Diastolic murmurs were present in 28% of patients followed beyond 1 month and increased very slightly with time. Systemic embolism was not recorded in any patient despite the fact that anticoagulants were not used. The clinical results were judged to be good or excellent in 89% of patients. It is concluded that homograft replacement of the aortic valve gives satisfactory results with a low incidence of late valve failure.

Temporal arteritis causing admission to hospital in Auckland.

A restrospective eight year review of patients hospitalised with temporal arteritis in Auckland shows that the features of the disease were headache, tender swollen temporal arteries, weight loss and fever very common, and blindness occurred in a quarter of the patients with definite temporal arteritis. The importance of making the diagnosis is discussed.

Exercise testing after beta-blockade: improved specificity and predictive value in detecting coronary heart disease.

The value of exercise testing in detecting myocardial ischaemia resulting from coronary atheroma remains controversial. In order to increase the reliability of exercise testing, all its components (asymptomatic, haemodynamic, and electrocardiographic) have been scrutinised. In this study, concerned only with the electrocardiographic response to exercise, the incorporation of beta-blockade into the standard exercise procedure has improved specificity and predictive value without affecting sensitivity. Fifty patients with anginal pain and 50 asymptomatic subjects with an abnormal electrocardiogram were investigated by exercise testing before and after beta-blockade (oxprenolol). All subjects had coronary arteriograms and left ventriculograms, and the results of exercise testing were related to the presence or absence of obstructive coronary artery disease. Possible causes of false positive exercise tests were eliminated by echocardiography. Though beta-blockade was unreliable in distinguishing ischaemic from non-ischaemic resting electrocardiograms, it eliminated all the false positive electrocardiographic responses to exercise in both groups and did not abolish any of the true positive electrocardiographic responses. Thus, specificity and predictive value were improved without reduction in sensitivity. This technique may not necessarily be applicable to other groups of patients or to a random population, but the results of this study suggest it will be a useful additional routine procedure in the investigation of coronary heart disease.