Extended abstract of a paper presented at Microscopy and Microanalysis 2011 in Nashville, Tennessee, USA, August 7–August 11, 2011.

A brief discussion of the resonant magnetic scattering process is given. Results from recent studies of thin Fe films and Fe/Gd multilayers are used as examples to demonstrate the information can be obtained and the unique features of this technique: large resonant enhancement, sensitivity to magnitization, elemental specificity, and tunability of the penetration depth. Comparison is made with related techniques: magneto-optical Kerr effect, Faraday effect, and magnetic circular dichroism.

The development of micro- and nanofabrication, their applications, and their dependent industries has progressed to a point where a bifurcation of technology development will likely occur. On the one hand, the semiconductor industry (at least in the USA) has decided to develop EUV and SCALPEL to meet its future needs. Even if the semiconductor industry is successful in this (which is by no means certain) such tools will not be useful in most other segments of industry and research that will employ nanolithography. As examples, MEMS, integrated optics, biological research, magnetic information storage, quantum-effect research, and multiple applications not yet envisioned will not employ the lithography tools of the semiconductor industry, either because they are too expensive, insufficiently flexible, or lacking in accuracy and spatial-phase coherence. Of course, direct-write electron-beam lithography can meet many of these non-semiconductor-industry needs, but in other cases a technique of higher throughput or broader process-latitude is necessary. Our experience at MIT in applying low-cost proximity x-ray nanolithography to a wide variety of applications leads us to conclude that this technology can provide an alternative path of a bifurcation. A new projection lithography technique, zone-plate-array lithography (ZPAL), does not require a mask, can operate from UV to EUV to x-rays, and has the potential to reach the limits of the lithographic process.

A survey for leprosy among 565 armadillos from Louisiana and Texas found IgM antibodies to the phenolic glycolipid-l antigen of Mycobacterium leprae in 16% of the animals. There were no geographic trends in the distribution of prevalence rates between the sites and the disease probably has a much greater range. Repeat observations in one location showed significant seasonal variations in the observable antibody prevalence rate, but the yearly average remained similar. Infected armadillos tended to be heavier, and the females usually had plasma progesterone concentrations indicative of sexual maturity. Using these characteristics to stratify the populations into adult and sub-adult cohorts, variations in the observable leprosy prevalence rate were seen to be proportional to changes in the age structure of the populations. Leprosy appears to be maintained in steady state within some regions, and nearly a third of the adult armadillos in Louisiana and Texas harbour M. leprae.

Klebsiella aerogenes V9A carrying a lac plasmid in addition to its chromosomal operon showed strongly positive fermentation of lactose on MacConkey lactose agar plates, and was found to transport the lactose analogue thiomethyl-β-galactoside (TMG) at a rapid rate. The strain that had been freed of the plasmid showed moderate transport due to the chromosomal lac operon. When a plasmid bearing a mutation in lac Y was inserted into a strain with a normal Y gene, the resulting diploid became lactose-negative in phenotype. The presence of E. coli F′lac factors that carried lac Y mutations, whether deletions or missense or nonsense mutations, also rendered lac Y+Klebsiella lactose-negative. Such diploids, after growth in 1% lactose, transported TMG at a much lower rate than the corresponding plasmid-free lac Y+Klebsiella. However, this interference by lac Y− plasmids with the expression of the chromosomal lac Y gene was not seen when cells were induced with IPTG or when the chromosomal and plasmid lac operons were both constitutive. It was found that this effect of the plasmids was dependent on their possessing an intact lacZ gene.

Theoretical quantification of viscous effects in fluid flows is difficult, even if turbulence is absent, except when it is legitimate to simplify the Navier-Stokes equations in some way; for example by invoking the boundary-layer approximation in appropriate cases of interacting viscous and inviscid flow. The technical importance of viscous effects was thought sufficient incentive to re-examine a very simple flow configuration — namely plane, uniform and steady flow of an incompressible, viscous fluid toward a vanishingly-thin flat plate aligned with the undisturbed stream — in search of fresh insights into the general theory for viscous-inviscid interactions.

The strategy was to exploit the analogy between vorticity transport in a viscous fluid and heat conduction in a moving solid. The key to doing so was the realization that, if the perturbation of the undisturbed flow by the plate might be represented as the sum of a series of successive approximations, then the stream function of the viscous part of the flow field — not merely the vorticity which resulted from its existence — might be expressible at every stage as the solution of an analogous heat conduction problem.

Extended abstract of a paper presented at Microscopy and Microanalysis 2005 in Honolulu, Hawaii, USA, July 31--August 4, 2005

This article reports on the planning, development, and implementation of a large national Internet-based panel study of how Americans are coping with the terrorist attacks of September 11, 2001. The study was designed to determine predictors and correlates of risk and resilience, both cross-sectionally and longitudinally. In order to acquire timely and meaningful data, we developed/adapted an extensive set of measures, obtained human subjects approval, and posted a research Web site just 17 days after the attacks. This article describes the major hurdles we confronted and the guidelines we recommend regarding these topics, including the methodological trade-offs inherent in Internet-based research, information technology requirements and tribulations, human subjects issues, selection of measures and securing permission for their use, and the challenges of participant recruitment. We also discuss issues that we did not anticipate, including the survey intervention. We focus not on findings, but on the concrete procedural, administrative, technical, and scientific challenges we encountered and the solutions we devised under considerable time and resource pressures.

A recent paper of Ockendon et al. discusses the Fanno model for quasi-one-dimensional flow of gas in a tube, in situations where the flow is turbulent and the tube is long enough for wall drag to be important. Based on appropriate scalings and with associated boundary conditions they derive equations for similarity solutions and make predictions about travelling and evolving waves. In this paper the existence, uniqueness and asymptotic behaviour of these wave forms is proved rigorously. Techniques include shooting methods (both one- and two-parameter), appropriate changes of variables, and comparison techniques.

The meanings of abstract concepts depend on context. Perceptual symbol systems (PSS) provide a powerful framework for representing such context. Whereas a few expected difficulties for simulations are consistent with empirical findings, the theory does not clearly predict simulations of specific abstract concepts in a testable way and does not appear to distinguish abstract noun concepts (like truth) from their stem concepts (such as true).

Positron emission tomography (PET) scanning has recently been introduced into clinical practice but its usefulness in the management of head and neck cancer is not well defined. The aim of this prospective preliminary study was to examine the clinical value of fluorodeoxyglucose (FDG) – PET in patients with head and neck cancer treated by radiotherapy with surgery in reserve by (i) relating quantitative uptake of isotope to tumour type and histological grade and (ii) comparing the imaging findings of PET and magnetic resonance imaging (MRI) in post-radiotherapy assessment of tumour response. Twenty-one patients had pre-treatment PET and MRI scans and these were repeated four and eight months after treatment if there was no clinical relapse. Pre-treatment uptake of FDG using tumour to cerebellar ratio parameters was significantly related to the histological grade of squamous cancer (p = 0.04) but not to tumour type. Discordance of post-treatment PET/MRI findings in one case indicates a possible role for PET in the early detection of tumour recurrence. Other potential uses of PET scanning in the management of head and neck cancer are discussed.

Mobilisation of the latissimus dorsi muscle as a functional graft necessarily involves division of perforating arteries that enter the distal portion of the muscle, rendering it vulnerable to ischaemic damage when the muscle is stimulated electrically. Using a fluorescent microsphere technique we showed that the blood flow contributed by the thoracodorsal artery decreases in a proximal-to-distal direction, and that of the perforating arteries in a distal-to-proximal direction, but for neither does the flow decline to zero. This is consistent with earlier reports of anastomotic connections between the 2 arterial territories. We went on to use fluorescence microscopy to demonstrate the existence of these vascular anastomoses, the first such evidence obtained under physiological conditions of pressure and flow. In clinical applications, the existence of anastomotic connections offers the prospect of maintaining flow to the distal part of the grafted muscle without the delays inherent in neovascularisation procedures.