Iterative algorithm for optimal fiducials under weak perspective projection

In previous work, we designed space fiducials with the aim of making camera pose determination as noise‐insensitive as possible. These fiducials turned out to be sets of points that formed concentric regular polyhedra. Here, we apply an idea of Dementhon and Davis and test and analyze an iterative linear algorithm in conjunction with our optimal fiducials to increase the accuracy of the computed camera pose. We also analyze under what circumstances this iterative algorithm is guaranteed to converge to the correct solution. Comprehensive computer simulations illustrate the behavior of the algorithm and the degree of improvement in pose determination in case of convergence. © 2009 Wiley Periodicals, Inc. Int J Imaging Syst Technol, 19, 27–36, 2009     

Contingent negative variation and cognitive performance in hypotension

The difference in attention and cognitive performance between 26 hypotensive (systolic blood pressure < 100 mmHg and diastolic blood pressure < 60 mmHg) and 22 normotensive female university students was assessed. Attention was examined with contingent negative variation (CNV) recorded using light and tone as S1 and S2. Cognitive performance was assessed by free recall of a list of words and two German tests of cognitive speed performance and sustained attention: Zahlen-Verbindungs-Test and d2. The hypotensive participants demonstrated a lower increase in negativity on the CNV. Moreover, in the free recall test, hypotensive individuals remembered fewer words, in comparison with normotensive subjects. Scores for hypotensive individuals on the Zahlen-Verbindungs-Test and d2 were also lower. No difference was found in reaction times to imperative stimuli (S2).     

Lock-granularity analysis tools in SVR4/MP

The design of the SVR4/MP multiprocessing system with fine-grained locking is discussed. SVR4/MP scales efficiently to eight processors under a database transaction processing workload and typical multiuser benchmarks. In developing SVR4/MP, initial lock placement was deemphasized and rapid, iterative tuning of lock placement was the focus. Sophisticated tools were used to perform iterative overall performance and scalability tuning of the operating system. The tools developed to determine lock granularity quantitatively are described and an example of their use to optimize overall system efficiency is presented     

The introduction of obstetric forceps in Norway--a 250-year anniversary

Johan Gottfried Erichsen (1713-68), born in Germany and chief medical officer in Bergen from 1747, was probably the first to perform a forceps delivery in Norway, on 14 February 1748. The mother, who had been in labour for five days, survived; the child, however, did not. The obstetric forceps had been a secret in the Chamberlen family and had become more widely known only a few decades earlier. Erichsen, who was the first man-midwife in Norway, had learned obstetrics in Paris by the younger Grégoire. He mastered both the techniques of internal version and forceps delivery. This article describes Erichsen's medical and obstetric background and his qualifications for operative obstetrics. He worked in the period when the obstetric forceps changed obstetrics, birth delivery became an arena also for men, and a part of medicine. Obstetrics was established as a science and physicians had a tool whereby also children could be saved during complicated delivery.     

Studies of 1s2s 3S-1s2p 3P transitions in helium-like Ne8+ recoil ions using photographic spectroscopy

This work describes the application of the technique of photographic VUV spectroscopy to accurate measurement of the wavelength of the theoretically interesting 1s2s ³S₁-1s2p ³P₂ transition in helium-like Ne⁸⁺ in a recoil ion source. Good resolution is obtained, and a preliminary value of 124.815±0.002 nm is found for the wavelength.     

Sre—a syntax recognizing editor

This paper presents a syntax-directed editor dubbed SRE, for syntax recognizing editor. Unlike other syntax-directed editors, SRE enables the user to edit programs with nearly the same natural and unrestrictive ease as a conventional text editor. In addition, it helps identify syntax errors and many typing errors before leaving the editor and attempting to compile a program. Programs are also formatted during entry, thereby providing immediate visual feedback of the recognized structure. The editor replaces the scanner/parser pass of a conventional compiler and thus reduces compilation time substantially.     

Scanning-electron-beam anomalous transmission patterns

The operating conditions required to obtain scanning-electron-beam anomalous transmission (SEBAT) patterns were investigated and the factors likely to limit the range of materials to which the technique may be applied were studied. It was found that the SEBAT technique is less restricted than is transmission electron microscopy. SEBAT patterns were obtained on a Geoscan X-ray microanalyser from samples of Si, Ge, Ag, CdS, NaCl, epitaxial Si on sapphire, mineralogical mica, and galena. The geometry of SEBAT patterns is discussed and it is emphasised that they are not Kikuchi patterns despite the very close resemblance.     

Cerebral angiography with iohexol. A multicentre clinical trial

An open multicentre clinical trial with the new non-ionic contrast medium iohexol is reported. A total of 38 adult patients were included in the series. No serious side effects or complications occurred. The impression was that subjective reactions were less marked with iohexol than what is usually observed with conventional ionic contrast media.     

The structure of epitaxial films of ZnS evaporated onto NaCl in a vacuum

The defect structures of epitaxial films of ZnS evaporated onto NaCl in vacuum were studied by transmission electron microscopy. Included grains of doubly-positioned wurtzite-structure material were found in many of the monocrystalline sphalerite-structure films. No twins or wurtzite grains in other orientations were ever observed.Numerous {111} planar defects were present in the films that were grown free of included grains. Interaction between doubly diffracted electron beams, arising from the 111 streaks due to the planar defects and the direct beam produced characteristic systems of fine-scale fringes and dots which dominated the appearance of the micrographs. Annealing in vacuum and in H₂S failed to eliminate the planar defects.