Sustainable intensification through rotations with grain legumes in Sub-Saharan Africa: A review.

We conducted a systematic review of literature on the residual effects of grain legumes in cereal-based systems of sub-Saharan Africa (SSA) to quantify the magnitude and variability of rotational effects, to explore the importance of environmental and management factors in determining variability and to evaluate the evidence of the different mechanisms that explain rotational effects. We retrieved 44 unique publications providing 199 observations comparing continuous cereal performance with that of a grain legume-cereal rotation. The overall mean yield increase of 0.49 t grain ha-1, equal to an increase of 41% of the continuous cereal yield, is highly significant, but the variability in residual effects is large. Effects were more pronounced in southern Africa, the highlands of East Africa and the Guinea savannah, and less in the humid forest/derived savannah of West Africa and the Sudano-Sahelian zone. Maize showed stronger yield responses after a legume than millet and sorghum. Agro-ecological zone and cereal type were however confounded. All grain legume types significantly improved cereal yields, with stronger residual effects observed after soybean and groundnut than after cowpea. Fertiliser N application to cereals reduces the residual effects of legumes, but the response at 60-120 kg N ha-1 still equalled 0.32 t ha-1 or 59% of the response when no N is applied. The sustained benefits with large N applications indicate the importance of non-N effects. While mechanisms for improved soil P availability after grain legumes have been studied in some detail, it remains uncertain how important these are in farmers' fields. Grain legumes are unlikely to have a major influence on the availability of nutrients other than N and P, or on soil pH. Beneficial impacts of grain legumes on soil organic matter content can occur if legumes contribute to a greater overall cropping productivity, but studies generally report no such impacts. Evidence of impacts of grain legumes on weeds is limited to striga. Studies on the impacts on nematode pressure in cereals are inconclusive, probably because legumes act as a host for some of the key nematode genera that harm maize. The impact on the pressure of other pests and diseases in cereals is probably important, but evidence on this from SSA is lacking. Future research on N2-fixation by grain legumes and residual N benefits should focus on explaining the wide variability observed among sites. There is a clear need for more detailed mechanistic studies to assess the occurrence and relevance of non-N effects of grain legumes, particularly in relation to common pests and diseases in cereals.

Fast and accurate automated measurements in digitized stereophotogrammetric radiographs.

Until recently, Roentgen Stereophotogrammetric Analysis (RSA) required the manual definition of all markers using a high-resolution measurement table. To automate this tedious and time-consuming process and to eliminate observer variabilities, an analytical software package has been developed and validated for the detection, identification, and matching of markers in RSA radiographs. The digital analysis procedure consisted of the following steps: (1) the detection of markers using a variant of the Hough circle-finder technique; (2) the identification and labeling of the detected markers; (3) the reconstruction of the three-dimensional position of the bone markers and the prosthetic markers; and (4) the computation of micromotion. To assess the influence of film digitization, the measurements obtained from nine phantom radiographs using two different film scanners were compared with the results obtained by manual processing. All markers in the phantom radiographs were automatically detected and correctly labeled. The best results were obtained with a Vidar VXR-12 CCD scanner, for which the measurement errors were comparable to the errors associated with the manual approach. To assess the in vivo reproducibility, 30 patient radiographs were analyzed twice with the manual as well as with the automated procedure. Approximately, 85% of all calibration markers and bone markers were automatically detected and correctly matched. The calibration errors and the rigid-body errors show that the accuracy of the automated procedure is comparable to the accuracy of the manual procedure. The rigid-body errors had comparable mean values for both techniques: 0.05 mm for the tibia and 0.06 mm for the prosthesis. The reproducibility of the automated procedure showed to be slightly better than that of the manual procedure. The maximum errors in the computed translation and rotation of the tibial component were 0.11 mm and 0.24, compared to 0.13 mm and 0.27 for the manual RSA procedure. The total processing time is less than 10 min per radiograph, including interactive corrections, compared to approximately 1 h for the manual approach. In conclusion, a new and widely applicable, computer-assisted technique has become available to detect, identify, and match markers in RSA radiographs and to assess the micromotion of endoprostheses. This new technique will be used in our clinic for our hip, knee, and elbow studies.

The DICOM review stations: are they truly different?

Digital acquisition systems are widely used nowadays. The digitization of the cath lab environment is now directed towards the change in the exchange media from an analog (i.e. cinefilm) to a digital (i.e. CD-R) medium. An important consequence of this development is the need for another type of review system. This article focuses on the replacement of the cineprojector by a digital equivalent: the DICOM review station. Since the technologies differ fundamentally, the DICOM review station has very little in common with its analog predecessor. This article explains the basics of DICOM review stations. Different approaches, both in hardware and in software, are possible, each showing their advantages and drawbacks. The impact of choices made by the industry will be illustrated by a number of commercially available DICOM review stations. Further, the article discusses the topics of diagnostic image quality and performance. In our opinion, these are the major topics when it comes to an objective comparison of the capabilities of DICOM review stations. The relation of these subjects with design choices in terms of hardware and software are discussed.

Quantitative coronary arteriography: current status and future.

Quantitative coronary arteriography (QCA) has been accepted as a means for the objective assessment of vessel sizing. Gradient field transform (GFT) is now available as a third generation QCA approach for the quantification of complex morphology. In the meantime the DICOM-3 (DICOM: Digital Imaging and Communications in Medicine) standard has been accepted for the exchange of digital data acquired in a catheterization laboratory. Issues to be resolved in digital imaging include the basic question of whether the commonly used matrix size of 512 x 512 pixels and 8 bits of density resolution is really sufficient to appreciate the same fine details as are visible on cinefilm. Other major issues of differences between the conventional cinefilm and the modern digital approach are edge enhancement and image compression. We believe that digital imaging and the DICOM-3 standard are here to stay; although the transition period may take longer and be hampered in practice by more hurdles than were originally anticipated, in a few years' time, 35-mm film will be an exception.