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Notes: The combination of spin-polarization detection with core-level photoemission to give spin-polarized electron spectroscopy for chemical analysis provides new information on the oxidation of an iron surface. During the initial stage of oxidation the predominant phase is of a ferrimagnetic γ-Fe2O3 form. The observed antiferromagnetic coupling of this oxide with the iron substrate is attributed to the superexchange interaction mediated by an oxygen ion. This provides evidence for a site exchange mechanism during the initial oxidation. Annealing transforms this oxide into an antiferromagnetic FexO form which is also present at the initial stage.

Notes: Summary A programme of home-based intervention with two groups of pre-school severely subnormal children and their parents has produced apparently contradictory results; frequently visited children after initial superiority over infrequently visited children, later showed a deceleration in intellectual growth. Less frequently visited children conversely showed a rise in performance after an initial decrement. The interpretation is advanced that parents in the latter group were less dependent on the visiting therapist, and more able to take positive action to assist their children, and improve their own situation.

Notes: Objectives  To model the determinants of serious operative and post-operative complications of hysterectomy and their potential risk factors.Design  A prospective cohort of women undergoing hysterectomies for benign indications in 1994/1995, with a six-week postsurgery follow up.Population and setting  A total of 37,512 women from 276 NHS and 145 private hospitals in England, Wales and Northern Ireland, originally recruited to compare the outcomes of endometrial destruction with those of hysterectomy.Methods  Gynaecologists reported hysterectomies for non-malignant indications carried out during a 12-month period beginning in October 1994 and follow up data were obtained at outpatient follow up six weeks postsurgery. Odds ratios of severe complications by indication and method, adjusting for measured intrinsic risk factors, were calculated.Main outcome measures  Severe operative and post-operative complications.Results  Severe operative complications occurred in 3%. The risk decreased with age and increased with greater parity and history of serious illness. Women with symptomatic fibroids (4.4%, 95% CI 3.9–4.9) experienced more complications than women with dysfunctional uterine bleeding (3.6%, 3.2–3.8), adjusted odds ratio (OR) = 1.3 (95% CI 1.1–1.6). Laparoscopic procedures (6.1%) doubled the risk of operative complications of abdominal hysterectomy (3.6%) (adjusted OR = 1.9, 1.5–2.5). Post-operative complications occurred in around 1% of women, with a slight decrease with increasing age, and the strongest risk factor was a history of operative complications. Relative to dysfunctional uterine bleeding (1.0%), a higher risk for fibroids (1.2%) persisted after adjustments (RR = 1.5, 1.1–2.0). Both vaginal (1.2%) and laparoscopic (1.7%) techniques had significantly higher adjusted risks than abdominal operations (0.9%), RR = 1.4 (1.0–1.9) and RR = 1.6 (1.0–2.7). There were no operative deaths; 14 women died within the six-week postsurgery (a crude mortality rate of 3.8/1000, 2.5–6.4).Conclusions  Hysterectomy is a common, routine surgery with comparatively rare serious complications. However, younger women, women with more vascular pelvises, who undergo hysterectomy, especially laparoscopically assisted vaginal surgery for symptomatic fibroids, are at most risk of experiencing severe complications both operatively and post-operatively. Therefore, a less invasive alternative treatment for symptomatic fibroids could particularly benefit this group of women, while less invasive treatments for dysfunctional uterine bleeding, such as various methods of endometrial ablations or resections, would need to meet the current low levels of clinical complications in order to replace hysterectomy.

Notes: We have developed an imaging photoelectron spectrometer based on a simple electrostatic immersion lens with the capability of measuring photoemission intensity as a function of the parallel component of electron wave vector throughout the Brillouin zone. The image is a simple rectilinear mapping of the k(parallel) component of the wave vector in reciprocal space. Using a retarding field-energy selection system, it is possible to energy select and image the various states below the Fermi energy. We obtain an energy resolution of 0.3 eV and a k(parallel) resolution of 0.04 A(ring)−1. The distribution of photocurrent is amplified onto a phosphor screen by a channel electron multiplier array. The image on the screen is then picked up with a charge-coupled device (CCD) camera so that the digitized image can be both position and energy analyzed. The performance of the system is demonstrated by imaging the photoelectron distribution from a Cu(001) single crystal. We find that the intensity distribution of emission in k space reflects the dispersion of the projected bulk energy band structure.

Notes: We have determined the ground state configurations of model molecular dipolar clusters using Monte Carlo simulations. Cluster sizes ranged from N=3 to N=20. The molecular models consisted of spherically symmetric hard sphere or Lennard-Jones interactions, as well as dipole–dipole, dipole–quadrupole, and quadrupole–quadrupole interactions. Molecular polarizability was also included in some calculations. We first found the ground state configurations of dipolar hard sphere clusters, and then systematically increased the quadrupole moment and molecular polarizability from zero up to typical values for small molecules. The relevance of our results to real molecular clusters is discussed.

Notes: Phase separation in binary liquid Lennard-Jones clusters is investigated employing computer simulation methods. Clusters ranging in size from 50 to 240 particles are considered with special emphasis on systems with equal numbers of A and B particles. Cluster morphology is systematically explored by varying the ratios, α=εAB/εAA, β=εBB/εAA, Γ=σAB/σAA, and Δ=σBB/σAA, where σ and ε are the Lennard-Jones size and energy parameters. A detailed α, β "phase diagram'' is presented for the case Γ=Δ=1. Stable phase separated clusters are shown to fall into two general classes: elongated clusters of cylindrical or dumbbell shape, the ends of which are A-rich and B-rich phases, and spherical coated clusters consisting of a core of one species coated by the other. More quantitative structural information is given in the form of interfacial density profiles. We also propose two theoretical models for phase separation in binary clusters. One is a simple macroscopiclike droplet approach and the other is a mean field lattice model. Both simple models capture many of the important physical features observed in the computer simulations. Together they provide insight into the nature of phase separation in small systems.