Integration in the Fourier domain for restoration of a function from its slope: comparison of four methods

In some measurement techniques the profile, f(x), of a function should be obtained from the data on measured slope f(?)(x) by integration. The slope is measured in a given set of points, and from these data we should obtain the profile with the highest possible accuracy. Most frequently, the integration is carried out by numerical integration methods [Press et al., Numerical Recipes: The Art of Scientific Computing (Cambridge U. Press, Cambridge, 1987)] that assume different kinds of polynomial approximation of data between sampling points. We propose the integration of the function in the Fourier domain, by which the most-accurate interpolation is automatically carried out. Analysis of the integration methods in the Fourier domain permits us to easily study and compare the methods' behavior.

Patellar tendon-lateral femoral condyle friction syndrome: MR imaging in 42 patients

OBJECTIVE

To demonstrate the MR imaging findings that occur between the posterior inferolateral patellar tendon and the lateral femoral condyle in patients with chronic anterior and or lateral knee pain.

PATIENTS AND DESIGN

A retrospective review of the MR images in 42 patients who presented with chronic anterior or lateral knee pain was performed by two musculoskeletal radiologists. In 15 patients, post-contrast images were available.

RESULTS

Sagittal and axial imaging planes best demonstrated the patellar tendon and its relationship with the lateral femoral condyle. In 40 patients, there was obliteration of the fat planes and abnormal signal intensity in the lateral soft tissues of the inferior patellofemoral joint. Enhancement after administration of gadolinium was noted in all cases in which contrast was administered. Eighteen patients showed cystic changes in the soft tissues adjacent to the lateral femoral condyle in addition to fat plane obliteration. In two patients, only cystic changes were noted in the lateral soft tissues. Abnormal patellar alignment was noted in 37 patients. Patellar tendon pathology was seen in nine patients.

CONCLUSION

In evaluating anterior knee symptoms, MR imaging allows identification of changes that may be related to patellar tendon-lateral femoral condyle friction syndrome and that should be distinguished from other causes of anterior or lateral knee pain.

Fractional derivatives-analysis and experimental implementation

The fractional derivative spatial-filtering operator is useful for image-processing applications, particularly for examination of phase objects. Experimental implementation is difficult because the mask function combines both amplitude and phase. We present a simple one-dimensional analysis of the fractional derivative operation and note similarities with the fractional Hilbert transform. We demonstrate how to encode these amplitude and phase masks using a phase-only liquid-crystal spatial light modulator and present experimental results. Finally, we introduce a radially symmetric extension of this operation that is more useful for objects having an arbitrary shape.

An integrated simulator for surgery of the petrous bone

This paper describes work being undertaken as part of the IERAPSI (Integrated Environment for the Rehearsal and Panning of Surgical Intervention) project. The project is focussing on surgery for the petrous bone, and brings together a consortium of European clinicians and technology providers working in this field. The paper presents the results of a comprehensive user task analysis that has been carried out in the first phase of the IERAPSI project, and details the current status of development of a pre operative planning environment and a physically-based surgical simulator.

[Larval susceptibility to chemical insecticides of two Aedes aegypti populations]

OBJECTIVE

Insect susceptibility has been one of the most important aspects to be monitored in public health programs for vector control. The purpose of the study is to assess the susceptibility to chemical insecticides of Aedes aegypti larvae in both areas under vector control and no vector control.

METHODS

World Health Organization standard bioassays for diagnostic concentration and multiple concentrations were performed in mosquito larvae collected in an area under no vector control (Campinas, SP) and an area under vector chemical control (Campo Grande, MS), in Brazil.

RESULTS

Potential resistance to a diagnostic concentration of temephos (DC=0.04 ppm) was registered for an Ae. aegypti larval population collected in Campinas. Multiple concentration tests confirmed the larvae resistance, with 24.5% of them surviving at the 0.0125 ppm concentration. Bioassays with the organophosphate fenitrothion (DC=0.08 ppm) and pyrethroid cypermethrin (DC=0.01 ppm) in the same population revealed their susceptibility to these agents. Bioassays carried out in an Ae. aegypti larval population collected in Campo Grande showed their susceptibility to temephos (DC=0.04 ppm) and cypermethrin (DC=0.01 ppm). LC50 and LC95 for cypermethrin (CE25), cyfluthrin (CE5), betacyfluthrin (SC1.25) and propoxur (CE20) were determined for Ae. aegypti. Using the Rockefeller standard strain values, ratios of resistance were estimated: 2.9, 2.2, 2.4 and 1.3 for LC50 and 3.5, 2.6, 3.9 and 1.3 for LC95, respectively.

CONCLUSION

The findings reinforce the need for routinely monitoring pesticide efficacy as a very important step in vector control management programs.

Amplitude Apodizers Encoded onto Fresnel Lenses Implemented on a Phase-Only Spatial Light Modulator

We show that both a lens and a nonuniform amplitude transmission filter can be encoded simultaneously onto a twisted nematic liquid-crystal spatial light modulator (SLM) working in the phase-only mode. The inherent equivalent apodization that is due to the pixelated structure of the SLM is compensated for. In addition, different types of nonuniform transmission pupil such as transverse apodizing, transverse hyperresolving, and axial hyperresolving (multifocusing) filters are implemented. The excellent agreement between numerical and experimental results shows the capability of this method to encode amplitude apodizers on a phase-only SLM.

Functional recovery of skilled forelimb use in rats obliged to use the impaired limb after grafting of the frontal cortex lesion with homotopic fetal cortex

The long-term effect of transplanting embryonic frontal cortex into a unilateral frontal cortex lesion has been studied in adult rats. Before surgery, activity in an open field, muscular strength of both forelimbs, and performance in a paw-reaching-for-food task were scored in 26 rats. In 21 animals a unilateral cortex lesion was then made in the forelimb motor area of the hemisphere contralateral to the preferred paw in the paw-reaching-for-food task, while the other 5 animals were sham-operated. On retesting, the lesion animals changed the preferred paw. A solid homotopic transplant of embryonic tissue (embryonic day 17) was then placed in the lesion cavity in 11 of the lesion rats. Three months later neither lesion alone nor lesion plus transplantation affected open field behavior and muscular strength, but the lesion permanently affected performance in the paw-reaching-for-food task, as shown by a change of preferred paw and a functional deficit in the paw contralateral to the lesion. Transplantation ameliorated the deficits caused by the lesion, but this was only evident when animals were forced to reach with the paw contralateral to the lesion plus transplant. The behavioral results were independent of the size of the lesion and graft. Connections between graft and host tissue were studied by means of the fluorescent tracer 1,1'-dioctadecyl-3,3,3'3'-tetramethylindocarbocyanine perchlorate (DiI). A dense array of labeled fibers was found in the host cortex adjacent to the transplant. The results suggest that functional recovery depends on grafting but is only evident when the animal is obliged to use the affected limb.

Chromosomal comparisons among and within populations of Simulium (Chirostilbia) pertinax (Diptera, Simuliidae)

Chromosomal studies were carried on six larval populations of Simulium (Chirostilbia) pertinax from different locations in Brazil. Larvae were collected in the states of Paraná, Rio Grande do Sul, Rio de Janeiro and São Paulo. Polytene chromosome map comparisons within and among populations showed no differences in banding pattern, except for some limited polymorphism (secondary NOR and four band polymorphisms). There were no chromosomal variations associated with the resistance or susceptibility of the larvae to temephos. The chromosomal homosequentiality found among the six populations suggests that S. pertinax may be a monomorphic species.

LUMO energy of model compounds of bispyridinium compounds as an index for the inhibition of choline kinase

Eleven derivatives of 1,1'-[1,2-ethylenebis(benzene-1,4-diylmethylene)]bis(4-pyridinium) dibromides bearing various groups at C-4 of the pyridinium moiety were synthesized and examined for their inhibition of choline kinase (ChoK) and antiproliferative activities. The C-4 substituents include electron-releasing, neutral or electron-withdrawing groups. A one-parameter regression equation has been derived which satisfactorily describes the ex vivo inhibitory potency of ChoK of the title compounds. The electronic effect plays a critical function in the ex vivo inhibition of ChoK although the role of electrostatic interactions could be altered due to a solvation process of both ChoK and ligands.

Differential interleukin-8 response of intestinal epithelial cell line to reactogenic and nonreactogenic candidate vaccine strains of Vibrio cholerae

In this study, we analyzed whether attachment of Vibrio cholerae vaccine strains to human intestinal epithelial cells can induce an interleukin-8 (IL-8) response. The IL-8 transcripts were detected by PCR amplification of reverse-transcribed mRNA, and the gene product secretion was measured by an enzyme-linked immunosorbent assay. Infection of monolayers of the undifferentiated HT29-18N2 cell line with reactogenic (JBK70 and 81) and nonreactogenic (CVD103HgR and 638) vaccine strains of V. cholerae resulted in markedly higher IL-8 expression by epithelial cells exposed to reactogenic strains than by cells exposed to the nonreactogenic strains. Additionally, epithelial cells produced IL-8 transcripts following stimulation with cholera vaccine strains in a concentration-dependent manner. These results represent a new insight into the inflammatory component of reactogenicity and could be used as a predictive marker of vaccine reactogenicity prior to human testing.

Optimal multichannel estimation of the location of a target with nonoverlapping noise

We propose a new algorithm for estimating the location of an object in multichannel images when the noise is spatially disjointed from (nonoverlapping with) the target. This algorithm is optimal for nonoverlapping noise and for multichannel images in the maximum-likelihood sense. We consider the case in which the statistical parameters of the input scene are unknown and are estimated by observation. We assess the results for simulated images with white and Gaussian background, for a large scale of variances of the background noise, and different values of the contrast in the scene. We compare the results of this algorithm with the results obtained with two other algorithms, the optimal algorithm for monochannel nonoverlapping noise and the optimal algorithm for multichannel additive noise, and we show that in both cases improvement can be obtained. We show the efficiency of the estimation for real input scenes when the background noise is correlated clutter noise. This algorithm has the same complexity as correlation, and the improvement is obtained with no more calculation cost than with classic methods.

From a classic approach in cancer chemotherapy towards differentiation therapy: acyclic and cyclic seven-membered 5-fluorouracil O,N-acetals

Novel derivatives of 5-fluorouracil (5-FU) possessing a broader spectrum of antitumor activity and fewer toxic side effects than 5-FU have been sought. Herein, we report three different types of 5-FU O,N-acetals: a) a novel class of 5-fluorouracil-containing acyclonucleosides. The antitumor activities of such compounds were assessed against HEp human cells showing that (RS)-1-¿[3-(2-hydroxyethoxy)-1-cyclopentoxy]propyl¿-5-fluorouracil 3c is 4-fold more active than 5-FU. (RS)-1-¿[3-(2-hydroxyethoxy)-1-isopropoxy]propyl¿-5-fluorouracil 3b has important potential advantages over 5-FU because of its lower toxicity and its ability to induce myogenic differentiation in rhabdomyosarcoma cells. Our results suggest that this drug may be useful for differentiation therapy in this type of tumor; b) within the cyclic prodrugs of 5-FU, a series of new ring-expanded isosteres (1,4-oxaheteroepanes) of Ftorafur were synthesized. The level of diastereoselectivity in the preparation of cis and trans 1-(3-chloromethyl)-1,4-dioxepan-5-yl)-5-fluorouracil, although modest, suggests a potentially general approach for controlling the stereochemistry of this unexplored class of reactions involving the preparation of 5-FU seven-membered O,N-acetals; c) new 5-FU acyclic analogs containing two 5-FU moieties at both ends of the molecules with a linker having two amide bonds have been designed and synthesized. These bis(5-FU-O,N-acetals) show interesting antineoplastic activities against the HT-29 cell line.

Fully complex synthetic discriminant functions written onto phase-only modulators

Synthetic discriminant functions (SDF's) are an effective tool for pattern-recognition applications. However, their experimental implementation is difficult because of the difficulty in writing full complex modulation functions onto spatial light modulators (SLM's) with restricted coding domains. Iterative methods are required for the implementation of SDF filters in real SLM's. A great deal of experimental research has been done with phase-only filters because they can be successfully implemented with liquid-crystal SLM's. We have recently introduced a technique for encoding arbitrary amplitude information onto the phase-only filter, thus allowing us to encode an arbitrary complex function onto a phase-only SLM. We apply this technique to the generation of arbitrary complex SDF filters, thus avoiding the necessity of iterative algorithms. We examine the discrimination capabilities of fully complex SDF filters designed with different parameters and constraints. Experimental results obtained with liquid-crystal SLM's are included.

Inherent apodization of lenses encoded on liquid-crystal spatial light modulators

Focusing diffractive optical elements encoded in liquid-crystal spatial light modulators yields an inherent equivalent apodization of the focused spot as a result of the pixelated nature of these devices and the finite extent of each pixel. We present a theoretical explanation for and experimental evidence of this effect. We demonstrate an experimental procedure for measuring the apodization and a method to compensate for this effect.