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The small-signal a.c. response of Ba1−xLaxF2+xsolid solution crystals has been studied as a function of temperature and composition (10−3< × < 0.45) over a wide range of frequencies. The composition dependence of the bulk ionic conductivity has been analyzed in detail. For x<5×10−2conductivity enhancement is due to a rapid increase of the number of free F-interstitials, while for x>×10−2enhanced ionic motion of a solute independent number of F-interstitials occurs. In addition, the dielectric response of concentrated solid solutions is determined by broad distributions of dipole-like relaxations. The mobility enhancement and the concept of a critical mobility offer a plausible explanation for the fall in the Faraday transition temperature in solid solution crystals.

The human X chromosome is known to contain several disease genes yet to be cloned. In the course of a project aimed at the construction of a transcription map of the Xp22 region, we fully characterized a novel cDNA,Cxorf5(HGMW-approved symbol, alias71-7A), previously mapped to this region but for which no sequence information was available. We isolated and sequenced the full-length transcript, which encodes a predicted protein of unknown function containing a large number of coiled-coil domains, typically present in a variety of different molecules, from fibrous proteins to transcription factors. We showed that theCxorf5cDNA is ubiquitously expressed, undergoesalternative splicing, and escapes X inactivation. Furthermore, we precisely mapped two additionalCxorf5-related loci on the Y chromosome and on chromosome 5. By virtue of its mapping assignment to the Xp22 region,Cxorf5represents a candidate gene for at least four human diseases, namely spondyloepiphiseal dysplasia late, oral-facial-digital syndrome type 1, craniofrontonasal syndrome, and a nonsyndromic sensorineural deafness.

We have explored the usefulness of a cloned low-repetitive DNA element, termed RTVL-H, for the region-specific isolation of DNA cosmids from chromosome 21. Hybridization of the RTVL-H element as a probe to genomic Southern blots of DNAs from a chromosome 21-specific somatic cell hybrid panel demonstrated the presence of at least seven RTVL-H-related sequences in defined regions dispersed over the chromosome. Some of the RTVL-H sequences detected by using the chromosome 21-specific somatic cell hybrid panel were subsequently isolated from a chromosome 21-specific cosmid library and mapped using somatic cell hybrids. In general, close correspondence was found between mapping results obtained using the consensus RTVL-H probe on the chromosome 21-specific somatic cell hybrid panel and the more precise mapping obtained using cosmids. The results demonstrate that sequences such as the RTVL-H element can be used for isolating region-specific sequences. Copyright 1993, 1999 Academic Press

DNA probes are available for Duchenne muscular dystrophy (DMD) carrier detection and prenatal diagnosis. With probes for about 25 of the proximal portion of the gene, we found the proximal probes detected deletions in 23 of nonselected DMD boys, while a single distal probe detected 17 more as deletions. The combined percentage was 39 for all probes tested. Prenatal diagnosis and carrier detection are more accurate if deletions are mapped rather than by use of restriction fragment length polymorphism analysis. The effort involved in screening all affected boys for deletions is considerably less, and provides an accurate genetic marker for subsequent prenatal diagnosis in the family and prospective counseling for female relatives. It seems likely that, once the entire gene (cDNA) is available for screening, most DMD boys will show deletions.

The forward model, as derived in part I [A. J. Berkhout, J. Acoust. Soc. Am. 93, xxx (1993)], and the inversion scheme, as derived in part II [A. J. Berkhout and C. P. A. Wapenaar, J. Acoust. Soc. Am. 93, xxx (1993)], are extended to the elastic situation. The elastic forward and inverse problem are formulated in terms of matrices, similar as in the acoustic situation. Unlike in the acoustic situation, the matrices involved in the elastic problem each consist of 3×3 submatrices. For instance, the submatrices of the multi‐component data matrix @SV represent single‐component data matrices, each submatrix being related to a specific combination of source and receiver components. On the other hand, the submatrices of the multi‐wavetype reflection matrix @SR± represent single‐wavetype reflection matrices, each submatrix being related to a specific combination of incident and reflected wavetypes. In the discussion of the elastic forward model the multi‐component data matrix @SV at the acquisition surface is related to the multi‐wavetype reflection matrices @SR± in the subsurface. In the discussion of the inversion scheme it is shown how @SR± is obtained step by step from the multi‐component data matrix @SV . Once the multi‐wavetype reflection matrices @SR± have been determined the medium parameters can be much better resolved than in the acoustic situation.

Using the forward matrix model, as derived in part I [A. J. Berkhout, J. Acoust. Soc. Am. 93, xxx(1993)], it is shown that the first and main part of numerical acoustic imaging consists of a wave field extrapolation process by double matrix inversion. Physically, the wave field extrapolation process means that the downward propagation effects and the upward propagation effects are eliminated from the measurements. Next, the reflection information is extracted from the wave field extrapolation result. Optionally, the reflection information is translated to discipline‐oriented material parameters by some data fitting process. Double focusing, i.e., focusing in emission and focusing in detection, is closely related to the above numerical imaging process. Finally, it is shown that imaging of zero‐offset or puls‐echo data can be formulated by single matrix inversion, involving phase shifts only.

Differential Alu PCR fingerprint cloning was used to isolate a DNA probe from the Xp 11.4→p11.21 region of the human X chromosome. This novel sequence, cpXr318 (DXS742), detects a new submicroscopic deletion interval at the Norrie disease locus (NDP). Combining our data with the consensus genetic map of the proximal short arm of the X chromosome, we propose the physical order Xcen – DXS14 – DXS255 – (DXS426, TIMP) – (DXS742 – ([MAOB – MAOA -DXS7], NDP) – DXS77 – DXS228) – DXS209 – DXS148 -DXS196 – Xpter. The cpXr318 probe and a subclone from a cosmid corresponding to the DXS7 locus were converted into sequence-tagged sites. Finally, DXS742, DXS7, DXS77, and MAOA were integrated into a physical map spanning the Norrie disease locus.

We have developed a 32–interval deletion panel for human chromosome Xp22 spanning about 30 megabases of genomic DNA. DNA samples from 50 patients with chromosomal rearrangements involving Xp22 were tested with 60 markers using a polymerase chain reaction strategy. The ensuing deletion map allowed us to confirm and refine the order of previously isolated and newly developed markers. Our mapping panel will provide the framework for mapping new sequences, for orienting chromosome walks in the region and for projects aimed at isolating genes responsible for diseases mapping to Xp22.

For acoustic applications in which there is a ‘‘preferred direction of propagation’’ (the axial direction) it is useful to arrange the two‐way and one‐way wave equations into the same matrix‐vector formalism. In this formalism, axial variations of the wave vector are expressed in terms of lateral variations of the same wave vector. The two‐way wave vector contains the field quantities pressure and velocity (axial component only), whereas the one‐way wave vector contains waves propagating in the positive and negative axial direction. By exploiting the equivalent form of the two‐way and one‐way matrix‐vector equations, it appears to be possible to derive two‐way and one‐way reciprocity theorems that have an equivalent form but a different interpretation. The main differences appear in the boundary integrals for unbounded media, in the contrast terms, and (for the correlation‐type theorems) in the handling of evanescent waves. © 1996 Acoustical Society of America.

We have subjected C12D, a Chinese hamster hybrid containing only the human X chromosome, to 6-thioguanine selection. The majority of the derivative clones retained rearranged Xp-fragments, which were characterized by using a combination of enzyme markers, DNA probes, and in situ hybridization. Two of these, TG2 and TG5sc9.1, contained only an Xpter→p21 fragment and should be an ideal resource for directed cloning from this region. A possible mechanism for the specific retention of Xp-fragments is discussed.

As shown by Pierce [J. Acoust. Soc. Am. 87, 2292–2299 (1990)], the influence of the static pressure on sound propagation through the atmosphere is only of the second order. For very accurate predictions, the improvements suggested by Raspet etal. [J. Acoust. Soc. Am 91, 498–500 (1992)] can be used, but then other second‐order effects and cross products should be taken into account as well. The two‐dimensional Fourier transform can be used for three‐dimensional sound‐pressure predictions considering the method of stationary phase. Errors are well within 2% for common temperature and wind gradients, provided that the wind vector is parallel to the vertical plane through the source and receiver. For situations with a cross‐wind vector full three‐dimensional calculations are recommended. These situations were avoided in the original article [Nijs and Wapenaar, J. Acoust. Soc. Am. 87, 1987–1998 (1990)].

A method is introduced to calculate the influence of wind and temperature gradients in stratified media on sound propagating above an absorbing ground surface. It is based on the ‘‘two‐way wave equation’’ for the Fourier transforms of the sound pressure P and its derivative V. The vector containing P and V is stepwise extrapolated through the medium in the direction perpendicular to the ground surface, fulfilling the boundary conditions at the ground surface, at a top level, and at the source height. The propagation equations for P and V appear as simple plane‐wave equations, and computer (CPU) time within each layer is very low. Therefore, many thin layers (in the order of centimeters if desired) can be applied, and any complicated gradient can be used. Calculations for a homogeneous atmosphere, with a computer program based on this model, show an excellent agreement with previous models. When a wind profile is present, results are mainly compared with measurements by Parkin and Scholes [P. H. Parkin and W. E. Scholes, J. Sound Vib. 1, 1–13 (1964); 2, 353–374 (1964)]. They show very good agreement in the no‐wind and downwind cases. In the upwind situation, agreement is very good below 500 Hz. Above this value the model does not predict sound to penetrate into the shadow region, while Parkin and Scholes found (low) sound levels.

Je werkgever kan de tweede zorgbonus (van waarschijnlijk 200 - 240 euro) aanvragen tot en met dinsdag 27 juli. Wanneer kom je in aanmerking?

Several letters to the editor are presented in response to articles in previous issues including birdwatching in South Africa's Kruger National Park by Peter Borchert, collision with vehicles as a cause of bird deaths, and feedback on a letter in the June/July 2012 issue about European magpies.

Cattle abortion can significantly affect farm productivity and be an important cause of economic loss on beef and dairy farms. A questionnaire‐based survey, completed by 379 farmers and 134 veterinary surgeons from the UK and Ireland, investigated motivators and barriers towards abortion investigations and perceptions of cattle abortion. Participants were recruited using convenience sampling. Veterinary surgeons underestimated farmers' willingness to pay for an abortion investigation; 54 per cent of veterinary surgeons expected farmers to pay under 100£/€, compared with 46 per cent of farmers. Most farmers (27 per cent) were willing to pay 101–250£/€ and 12 per cent above 500£/€. The incidence threshold warranting abortion investigation was 4 per cent for veterinary surgeons and lower for farmers at 2 per cent, especially beef farmers, where 48 per cent indicated a 1 per cent incidence required attention. Seventy‐five per cent of dairy farmers used more than 2 per cent as their threshold. Eighty‐four per cent of veterinary surgeons and 95 per cent of farmers agreed on the same abortion definition. Veterinary surgeons and farmers agree on the definition of abortion; however, veterinary surgeons underestimate the willingness of farmers to engage with and pay for abortion investigations. A more proactive approach from veterinary surgeons, including improved communication and transparency around costs, expectations and clients’ goals can improve abortion investigation outcomes.

In Zoetermeer krijgen cliënten van dezelfde professional huishoudelijke hulp, persoonlijke verzorging en maaltijdzorg. Wat zijn de ervaringen?

Ook sociaal werkers zijn bang voor radicalisering. Maar om jongeren weerbaarder te maken, moeten ze door die angst heen, zegt pedagoog en onderzoeker Stijn Sieckelinck. In zijn boekReradicaliseren. Ronselen voor een betere wereld pleit Sieckelinck voor een sociale strategie tegen extremisme.

De reclassering zoekt samenwerking met gemeenten. Wat kunnen wijkteams doen als een ex-gedetineerde in de buurt komt wonen? ‘Ik vind sneller iets dat bij de motivatie en talenten past dan iemand van de reclassering.’

45-plus en voor langere tijd werkloos; vaak het begin van meer problemen. In Almere zijn ze er vroeg bij. ‘Mensen willen graag vertellen waarom ze zich schamen.’

Communication between farmers and veterinary surgeons is reported to differ when involving abattoir rejection data on cattle or sheep. Using surveys, distributed online and on paper at livestock markets, this study describes the interest and positive opinion of a sample of UK cattle and sheep farmers in receiving abattoir data. Forty‐nine per cent of respondents always received abattoir data (n=37/76). Over 80 per cent of respondents were interested in all suggested rejection conditions and particularly liver fluke and respiratory conditions. Eighty‐two per cent of farmers were willing to share data with their veterinary surgeon as the information could be used to inform health plans. The study findings indicate that having an accurate and consistent data system, which is easily accessible to farmers and veterinary surgeons, appears an essential next step to improve the use of existing abattoir data and enhance animal health, welfare and production.

Orf, a parapoxvirus, is a zoonosis causing a contagious pustular dermatitis, and has a high morbidity in sheep worldwide. Despite a vaccine being available, orf prevalence in England is estimated to be 2 per cent in ewes and 20 per cent in lambs​​. There is concern that farmers are not complying with the vaccination guidelines and therefore the objective of this study was to investigate if orf vaccine is used correctly on sheep farms in the UK and to identify barriers and motivators of sheep farmers to use the vaccine. The survey was completed by 570 respondents. The results show several areas of concern; only 27 per cent of respondents used the correct site (axilla), 37 per cent of respondents would use orf vaccine up to a week after opening a vial (shelf life is eight hours), 33 per cent of respondents would vaccinate their ewes too close to lambing and 73 per cent of respondents did not separate vaccinated and non‐vaccinated animals (both leading to infection risk for non‐vaccinated animals). When vaccinating, only 53 per cent of respondents were wearing gloves and 31 per cent washed their hands just before and immediately after vaccination. Results demonstrate that orf vaccination is not carried out correctly on all UK sheep farms, which is likely to affect vaccine efficacy. A concern around vaccine efficacy, the ‘hassle’ of the scratch administration, the ‘risk of making it worse’ and the zoonotic risk when vaccinating were the most common barriers for using orf vaccine, highlighting the importance of veterinary advice when prescribing orf vaccine.

In the final year of the course schools assess students to ensure a minimum level of knowledge and skills is achieved before graduation as a veterinary surgeon. Across the universities, different styles and combinations of assessments are used. A national assessment could provide a solution to maintain quality and potential employability of veterinary surgeons. The aim of this study was to identify barriers and motivators of veterinary educators from all veterinary schools in the UK and the Republic of Ireland towards a national assessment. Semistructured interviews were conducted with 16 academic staff members. Mixed opinions were expressed and many barriers as well as motivators were voiced. Four main themes were: harmonisation and benchmarking, confidence in quality, practical feasibility and stakeholder perspectives. The study identified a positive attitude towards a national assessment, particularly around improved quality and standards. However, the practical feasibility was perceived as a significant barrier for implementation. Before making changes to current assessments it is important to further research the barriers identified to confirm representativeness and to acquire evidence to accept or refute the perceived limitations.

Sciatic nerve damage in cattle could lead to pain, paralysis and lameness, creating welfare and productivity issues. Damage following intramuscular injection is highlighted in some clinical texts although there is no indication of prevalence. This cross‐sectional study investigated the anatomical size and position of the sciatic nerve in four dairy cattle type cadavers. To evaluate the risk of iatrogenic damage, 54 participants placed needles in the dorsal gluteal region of two cadavers each, as per their routine intramuscular injection method. The distance from needle tip to the sciatic nerve was estimated for each. Sixty‐nine per cent of injections were placed within 5 cm of the sciatic nerve. Direct nerve puncture occurred in the cadaver in poorest body condition. A short questionnaire revealed that 70 per cent of the participants regularly used the dorsal gluteal region for intramuscular injection and 50 per cent commonly used a volume of ≥20 mL at a single site. It is concluded that the sciatic nerve is at considerable risk of iatrogenic damage. The neck should be promoted as the optimum site for intramuscular injection and improved guidelines are required if the gluteal region is to remain in common use. A lateral site, between the tuber coxae and tuber ischium, is recommended.

Injectable veterinary medicinal products (VMPs) are widely used in cattle in the UK, and in particular vaccines are often used on large numbers of animals in the herd. The formation of injection-site lesions (ISLs) is a risk when using injectable products and has potential consequences for meat quality, animal welfare and beef industry income. This study used carcase observation in four abattoirs in England to determine ISL prevalence in beef cattle. Additionally, a questionnaire survey was used to investigate vaccination technique among UK beef farmers. The ISL prevalence was 4.1 per cent (95 per cent CI 3.4 per cent to 4.9 per cent). A potential difference between sites being used for vaccination and the distribution of ISLs on carcases suggested that factors other than vaccination were contributing to ISL incidence. Questionnaire responses highlighted deficits in good vaccination practices such as using the recommended site of injection and needle hygiene. The role of the veterinarian in knowledge transfer is crucial in providing practical injection advice when prescribing vaccines and other VMPs. This study identified factors to address when aiming to reduce ISL formation in UK beef animals.

The use of vaccines in the cattle industry is widespread; however, there is limited published guidance for use by decision‐makers such as farmers and vets. To best support vets in advising dairy farmers on the optimisation of vaccination strategies, it is important to understand how and why vets make decisions about recommending the vaccination of cattle. The objective of this study was to explore in‐depth farm animal vets’ motivators and barriers to the implementation of vaccination strategies on British dairy farms. Semistructured interviews were conducted with 15 vets. Results indicated that vets have a positive attitude towards the use of vaccination and have few barriers to advising its implementation. Vets appear to group farmers into three ‘character types’. This characterisation influences the vet–farmer relationship and how the vet communicates with the farmer. Vets required evidence of disease or a risk of disease as a motivator to advise vaccination. However, this seemed to be sometimes overruled by a risk‐averse attitude; resulting in vaccination being advised ‘just in case’. Crucially, the need for resources to support and build on the vet–farmer relationship is highlighted as an area requiring further exploration in order to optimise vaccination strategies on farm.

The article reports that scientists at TU Delft and the Colorado School of Mines have found broader physical applications for acoustic noise than previously thought possible. They have developed a unified theory to include acoustic noise in flowing and viscous media, electromagnetic noise in conducting media, and diffusive transport phenomena.

Le questionnaire K-BILD (King's Brief Interstitial Lung Disease), 15 items, évalue l’état de santé respiratoire au cours des pneumopathies interstitielles diffuses (PID) [1]. L’objectif de ce travail était de traduire et valider le K-BILD en français, italien, suédois, et néerlandais. Le questionnaire a été traduit et adapté en plusieurs étapes, et testé avec des patients lors d’entretiens structurés, selon les recommandations internationales. Des patients consécutifs avec PID ont ensuite rempli le K-BILD, le questionnaire respiratoire de Saint-George (QRSG), et le questionnaire Euroquol-EQ5D5L (EQ5D) à 2 reprises à 2 semaines d’intervalle. La version traduite du K-BILD a été jugée compréhensible et adaptée par les patients dans chacune des 4 langues. Puis 96 patients (49 hommes), dont 39 avec fibrose pulmonaire idiopathique (FPI) et 57 avec une autre PID, ayant une CVF de 77±20 % et une DLco de 55±20 %, ont rempli les 3 questionnaires. La cohérence interne était bonne (Cronbach α : 0,74–0,93). La validité du K-BILD était bonne en comparaison du QRSG (r=–0,89) et EQ5D (r=0,71), modérée avec la DLco (r=–0,58), et faible avec la CVF (r=0,38). Le K-BILD était reproductible sur 2 semaines, avec une corrélation intra-classe de 0,84–0,92 (n=86). Le K-BILD était discriminant en fonction de la gravité de la maladie (état de santé ressenti, utilisation de l’oxygène, fonction pulmonaire). La validité et la fiabilité du K-BILD étaient comparables au cours de la FPI et d’autres PID. En conclusion, le questionnaire K-BILD traduit a été validé pour évaluer l’état de santé perçu par les patients présentant une PID dans 4 langues dont le Français.

Vaccination is a widely used strategy for disease control in cattle in the UK and abroad. However, there has been limited research describing the uptake and use of cattle vaccines on UK farms. To describe the current uptake and usage of cattle vaccines in the UK. A questionnaire, available in paper and online format, was distributed to cattle farmers by convenience sampling. All UK cattle farmers were eligible to participate in the study. Eighty-six per cent of respondents (n=229/266) had vaccinated their cattle in the past year. Diseases most commonly vaccinated against were Bovine Viral Diarrhoea, Leptospirosis and Infectious Bovine Rhinotracheitis. Vaccination compliance was limited in certain areas, for example only 48 per cent of respondents stated that they administered the second dose in the primary course within the recommended timeframe, and 14 per cent of respondents stated that they vaccinated earlier than the youngest recommended age. Although outside the scope of this study, further work is needed to establish the extent of inadequate compliance and the effect this has on vaccine efficacy. The role of the veterinarian was highlighted as the main supplier of vaccines and preferred source of vaccination information. Respondents preferred to receive recommendations regarding vaccination by face-to-face communication with the veterinarian. The results provide a description of the current uptake and usage of cattle vaccines in the UK. Uptake is generally high but there are areas of usage of vaccines which could be improved upon. The veterinarian plays a key role as supplier of vaccines and a source of information for the majority of farmers. Although outside the scope of this study, further work is needed to establish the extent of inadequate compliance and the effect this has on vaccine efficacy. Although the respondents in this study represent a biased population of farmers, the findings indicate areas for future investigation in order to improve vaccination strategies in cattle in the UK.

The interaction of elastodynamic waves with imperfect interfaces is usually described by the so‐called linear slip model. In this model it is assumed that the particle displacement of an elastic wave at an interface jumps by a finite amount, linearly proportional to the stress at the interface. In this paper we postulate general boundary conditions at arbitrarily shaped imperfect interfaces for acoustic waves in fluids, elastodynamic waves in solids, electromagnetic waves in matter, poroelastic waves in porous solids, and seismoelectric waves in porous solids in such a way that they cover the linear slip model and other existing models for imperfect interfaces. These boundary conditions are expressed by a single matrix‐vector equation in the space‐frequency domain. Using this equation, we extend two unified reciprocity theorems (one of the convolution type and one of the correlation type) for the various wave phenomena, with an extra integral over the imperfect interfaces. By considering two special cases of these reciprocity theorems, we observe that (1) source‐receiver reciprocity remains valid when the source and receiver are separated by imperfect interfaces and that (2) the extra integral in the correlation‐type reciprocity theorem quantifies the power dissipated by the imperfect interfaces.

An acoustical reflection experiment is intuitively based on (i) downward wave propagation from the acquisition surface into the medium, (ii) reflection by inhomogeneities inside the medium, and (iii) upward propagation of the reflected waves to the acquisition surface. The acoustic and elastodynamic wave equations do not explicitly account for this intuitive distinction between downward and upward propagation. These wave equations govern the total wave field, which may be seen as a superposition of downward propagating and upward propagating wave fields. For this reason these equations are referred to as the two‐waywaveequations and their solutions are called two‐waywavefields. Analogously, the equations that explicitly govern downward and upward propagation are referred to as the one‐waywaveequations and their solutions are called one‐waywavefields. In this paper reciprocity and representation theorems are developed for one‐way wave fields. These theorems are the basis for a systematic discussion of acoustic reflection imaging in inhomogeneous fluids and in inhomogeneous anisotropic solids.

In modelling applications, recursive Kirchhoff-Helmholtz extrapolation through a layered medium requires plane-wave decomposition and synthesis at the layer interfaces in order to take transmission effects into account. For inverse applications (downward extrapolation of the measured data into the subsurface), this plane-wave decomposition and synthesis is superfluous: transmission effects are automatically taken into account, since the extrapolated two-way (downgoing and upgoing) wavefield is continuous at layer interfaces. Two-way wavefield extrapolation, however, is very sensitive to errors in the model of the layered medium. Therefore, in practice one-way extrapolation schemes are preferred. It appears that for backward extrapolation of the primary upgoing wavefield, the recursive Kirchhoff-Helmholtz approach again accounts automatically for transmission effects at the layer interfaces. This approach is particularly attractive for situations where the contrasts at the layer interfaces are high.

A general one-way representation of seismic data can be obtained by substituting a Green's one-way wavefield matrix into a reciprocity theorem of the convolution type for one-way wavefields. From this general one-way representation, several special cases can be derived. By introducing a Green's one-way wavefield matrix for primaries, a generalized Bremmer series representation is obtained. Terminating this series after the first-order term yields a primary representation of seismic reflection data. According to this representation, primary seismic reflection data are proportional to a reflection operator, ‘modified’ by primary propagators for downgoing and upgoing waves. For seismic imaging, these propagators need to be inverted. Stable inverse primary propagators can easily be obtained from a one-way reciprocity theorem of the correlation type. By introducing a Green's one-way wavefield matrix for generalized primaries, an alternative representation is obtained in which multiple scattering is organized quite differently (in comparison with the generalized Bremmer series representation). According to the generalized primary representation, full seismic reflection data are proportional to a reflection operator, ‘modified’ by generalized primary propagators for downgoing and upgoing waves. Internal multiple scattering is fully included in the generalized primary propagators (either via a series expansion or in a parametrized way). Stable inverse generalized primary propagators can be obtained from the one-way reciprocity theorem of the correlation type. These inverse propagators are the nucleus for seismic imaging techniques that take the angle-dependent dispersion effects due to fine-layering into account.

Acoustic reciprocity theorems have proved their usefulness in the study of forward and inverse scattering problems. The reciprocity theorems in the literature apply to the two-way (i.e. total) wavefield, and are thus not compatible with one-way wave theory, which is often applied in seismic exploration. By transforming the two-way wave equation into a coupled system of one-way wave equations for downgoing and upgoing waves it appears to be possible to derive ‘one-way reciprocity theorems’ along the same lines as the usual derivation of the ‘two-way reciprocity theorems'. However, for the one-way reciprocity theorems it is not directly obvious that the ‘contrast term’ vanishes when the medium parameters in the two different states are identical. By introducing a modal expansion of the Helmholtz operator, its square root can be derived, which appears to have a symmetric kernel. This symmetry property appears to be sufficient to let the contrast term vanish in the above-mentioned situation. The one-way reciprocity theorem of the convolution type is exact, whereas the one-way reciprocity theorem of the correlation type ignores evanescent wave modes. The extension to the elastodynamic situation is not trivial, but it can be shown relatively easily that similar reciprocity theorems apply if the (non-unique) decomposition of the elastodynamic two-way operator is done in such a way that the elastodynamic one-way operators satisfy similar symmetry properties to the acoustic one-way operators.

The locus DXS269 (P20) defines a deletion hotspot in the distal part of the Duchenne Muscular Dystrophy gene. We have cloned over 90 kilobase-pairs of genomic DNA from this region in overlapping cosmids. The use of whole cosmids as probes in a competitive DNA hybridization analysis proves a fast and convenient method for identifying rearrangements in this region. A rapid survey of P2O-deletion patients is carried out to elucidate the nature of the propensity to deletions in this region. Using this technique, deletion breakpoints are pinpointed to individual restriction fragments in patient DNAs without the need for tedious isolation of single copy sequences. Simultaneously,the deletion data yield a consistent restriction map of the region and permit detection of several RFLPs A 176 bp exon was identified within the cloned DNA, located 3’ of an intron exceeding 150 Kb in length. Its deletion causes a frameshift in the dystrophin reading frame and produces the DMD phenotype. This exon is one of the most frequently deleted exons in BMD≤DMD patients and its sequence is applied in a pilot study for diagnostic deletion screening using Polymerase Chain Reaction amplification