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Surface‐wave analysis is a key tool for seismologists, ranging from near‐surface characterization in geotechnical applications to global seismology. Even in exploration seismology, where surface waves are regarded as a kind of noise, the fact that they typically represent the bulk of the recorded energy makes an understanding of surface‐wave propagation important. On the other hand, the heterogeneity of the near surface can make such analyses difficult since the heterogeneity is responsible for scattering and mode conversion. Here, we show how multichannel seismic records of scattered surface waves can be used to obtain spatial images of the heterogeneity. We discuss both data processing and imaging and illustrate our method on laboratory‐scale data. Further, synthetic examples show that we can locate individual scatterers accurately, even when many scatterers produce interfering surface waves. Our laboratory results show that the method has the potential to locate near‐surface heterogeneities in the field.

We assessed the usefulness of wearing masks in preventing epidemic methicillin-resistantStaphylococcus aureus(EMRSA) carriage in nursing and physiotherapy staff on two dedicated EMRSA units. In the first phase of the study, members of staff were screened for EMRSA carriage immediately before and after periods of duty using nose, throat and hand swabs. During the second phase of the study, masks were worn by staff carrying out procedures associated with significant EMRSA exposure and examined for EMRSA as described for the first phase. Both phases were conducted over a period of two months. Forty-eight percent of nursing staff were colonized with EMRSA at some time during the first phase of the study. Wearing masks significantly reduced nasal, throat and hand carriage of EMRSA (P= 0.05). We conclude that the wearing of masks by healthcare workers performing certain activities for EMRSA positive patients may prevent transient colonization and hence may be a useful intervention in the control of EMRSA in the hospital environment.

A personal experience is recounted of operations in cases of tumour involving the humerus or femur with restoration by endoprostheses. Twenty-four patients were treated in this way from 1950 to 1969 inclusive and have been followed up for between four and twenty-four years. The patients selected for treatment have presented chondrosarcoma (ten), so-called benign giant-cell tumour of bone, usually recurrent (nine), angiomatous osteolysis (two), seemingly single thyroid or renal metastasis (two), and ununited pathological fracture after irradiation of a tumour (one). Development of the prostheses from early beginnings is outlined. Some points in surgical management are referred to. The complications and results are recorded.

The myogenic factors MyoD1 and myogenin contain a conserved region with similarity to the myc family of proto-oncogenes. To identify amphibian genes structurally and functionally related to these myogenic factors, we screened a Xenopus laevis embryo cDNA library under conditions of reduced stringency with probes corresponding to the myc-like helix-loop-helix motif of mouse MyoD1 and myogenin. Several distinct cDNAs that are highly related to each other and share extensive homology to MyoD1 were isolated. Transcripts from two of these genes, Xlmf1 and Xlmf25 (X. laevis myogenic factor), reach maximal levels of accumulation during gastrulation, remain at constant levels through early embryogenesis, and are found exclusively in skeletal muscles of adult frogs. The appearance of these transcripts early in development precedes the expression of cardiac alpha-actin, a molecular marker for mesoderm formation. A third cDNA, Xlmf11, contains an internal 351-base-pair deletion downstream of the myc homology region and encodes a truncated version of the protein encoded by Xlmf1. When expressed in mouse pluripotential stem cells, Xlmf1 activates the muscle cell differentiation program, resulting in expression of endogenous MyoD1, myogenin, and myosin heavy-chain genes and formation of multinucleated myotubes.

In addition to its orthopaedic interest, this case illustrates the special behaviour of fine particles of a synthetic material when implanted in the human body. These results may interest those engaged in the control of dusts in the plastics industry, for the inhalation of such dusts may well result in "implantation" of the material in the lung, with consequent histological changes.

Abstract: Hypertrophic scars are a particular type of scar that can form after any type of dermal injury. They are unsightly, red, elevated above nomal skin level, itchy and painful. At present no-one knows why these scars form. Due to the differences between scar tissue and normal skin it was decided to analyse skin tissue which at a later date would be compared to scar tissue. Split skin graft (epidemis) samples as well as full thickness skin (epidemis to demis) tissue were analysed using PIXE and RBS with a 2 MeV proton beam. The epidemis was compared to the demis to see if there were any variations between the two. In all the samples P, S, Cl, K, Ca, Fe, and Cd were detected and in a majority of the samples Zn and Ba were found, using PIXE. It was found that, between the epidemis and demis, there was an significant increase in P in the epidermis in both full thickness and split skin graft samples. Complementary elemental analysis was also performed using neutron activation, and Br, Na and Zn were detected.

Without Abstract:

In view of the fact that the postoperative treatment of cataract cases depends to some extent on the technic of the operation, I consider that it will not be amiss to review briefly the technic, or rather a certain feature of the technic, which appeals to me as being most rational, and which in my hands has stood the test of experimentation. The point to which I refer is the construction of an ample conjunctival flap as the knife emerges from the incision, the employment of which seems to produce the most rapid resolution and recovery, minimizes the risk of infection, and at the same time obtains the best possible vision and the greatest comfort to patients during convalescence.The great fundamental proposition which confronts the ophthalmic surgeon in the treatment of every cataract operation is how he may best prevent infection. This may be reduced to a minimim by

Due to ill-conditioning and the presence of noise in the data, tomographic inversion by traditional techniques usually requires some sort of smoothing, either to filter out small-scale variations in the solution which are beyond the resolution of the data or to produce smooth background models during the iterative inversion procedure. We shall describe the use of α-trimmed means for smoothing computed tomograms. The α-trimmed means range continuously from the median to the mean. They are all efficient computationally and can be tailored to smooth the tomogram without destroying sharp geological features, such as faults and reflecting layers, and without introducing artifacts. Further, the median and trimmed means close to it are statistically robust in the sense that they reject bursts of noise whereas the mean simply averages the noise into the solution and can therefore be adversely affected by outliers in the data. All of these filters can be applied directly to the computed tomogram after solution, or during the solution phase as a means to stabilize the inversion.

The role of all hematophagous Diptera or all except Tabanidae as potential vectors of anaplasmosis was assessed for 3 years in Mississippi by exposing groups of anaplasmosis-negative splenectomized steers in the presence of anaplasmosis-carrier steers. However, during the 1st year of the study, another group of Diptera, the eye gnats, Hippelates spp. (Chloropidae), also appeared to be potential vectors; the role of this group was therefore assessed during the 2nd and 3rd years of the study. Populations of insects were surveyed with light traps, animalbaited traps, collections from a bait steer, and eye gnat traps. Of the animals exposed to all Diptera, 32% contracted anaplasmosis. Of those protected from tabanids, none contracted the disease. Also, the animals protected from tabanids were protected from eye gnats.