An Efficient Procedure to Compensate for the Errors Due to the Probe Mispositioning in a Cylindrical Near-Field Facility.

This paper deals with the compensation of the probe mispositioning errors occurring in a cylindrical near-field (NF) facility due to the imprecise control of the linear and azimuthal positioners allowing the cylindrical scanning and/or to their limited resolution and to defects in the rails guiding the linear motion. As a result, 3-D errors in the positioning of the probe at any sampling point, as prescribed by the adopted non-redundant representation, affect the accuracy of the NF measurements. An efficient procedure is here proposed to properly compensate for these errors. It involves two steps. The former allows one to correct the mispositioning errors due to the deviation of each actual sampling point from the nominal measurement cylinder. The latter makes use of an iterative technique to restore the NF samples at any sampling point fixed by the used non-redundant representation from the ones obtained at the previous step and affected by 2-D mispositioning errors. Once these steps have been fruitfully applied, the so-compensated NF samples are effectively interpolated through a 2-D optimal sampling interpolation (OSI) formula to accurately reconstruct the input data required to perform the traditional cylindrical near-to-far-field transformation. The OSI representation is here developed by considering an elongated antenna under test as enclosed either in a prolate spheroid or in a cylinder terminated by two half spheres (rounded cylinder) in order to make the representation effectively non-redundant. Numerical test results, which thoroughly prove the efficacy of the devised procedure in correcting even severe 3-D mispositioning errors, are reported.

An Effective Near-Field to Far-Field Transformation with Planar Spiral Scanning for Flat Antennas under Test.

The goal of this article is to provide numerical and experimental assessments of an effective near-field to far-field transformation (NF-FF T) technique with planar spiral scanning for flat antennas under test (AUTs), which requires a non-redundant, i.e., minimum, number of NF measurements. This technique has its roots in the theory of non-redundant sampling representations of electromagnetic fields and was devised by suitably applying the unified theory of spiral scans for non-volumetric antennas to the case in which the considered AUT is modeled by a circular disk having its radius equal to half of the AUT's maximum dimension. It makes use of a 2D optimal sampling interpolation (OSI) formula to accurately determine the massive amount of NF data required by the classical plane-rectangular NF-FF T technique from the non-redundant data gathered along the spiral. It must be emphasized that, when considering flat AUTs, the developed transformation allows one to further and significantly save measurement time as compared to that required by the previously developed NF-FF T techniques with planar spiral scans based on a quasi-planar antenna modeling, because the number of turns of the spiral and that of NF data to be acquired depend somewhat on the area of the modeling surface. The reported numerical simulations assess the accuracy of the proposed NF-FF T technique, whereas the experimental tests prove its practical feasibility.

Reconstruction of the Far-Field Pattern of Volumetric AUTs from a Reduced Set of Near-Field Samples Collected along a Planar Spiral with a Uniform Step.

An efficient near-to-far-field transformation (NTFFT) technique, wherein the near-field (NF) measurements are acquired along a planar spiral with a uniform step to make the control of the involved positioners easier, is developed in this article. Such a technique is tailored for quasi-spherical, i.e., volumetric, antennas under test and makes use of a reduced number of NF data. An effective two-dimensional sampling interpolation algorithm, allowing the accurate reconstruction of the input NF data for the standard NTFFT with plane-rectangular scan, is obtained by setting the spiral step equal to the sample spacing required for interpolating along a radial line according to the spatial bandlimitation properties of electromagnetic fields, and by properly developing a non-redundant representation along such a spiral. Tests results are reported to demonstrate that the proposed NTFFT technique retains the same accuracy as the standard plane-rectangular one.

The relationship between self-rated disability, fear-avoidance beliefs, and nonorganic signs in patients with chronic whiplash-associated disorder.

OBJECTIVES: The purpose of this study was to determine the role of standard and novel (cervical) nonorganic signs in patients with chronic whiplash-associated disorder (WAD). METHODS: Chronic WAD I to III patients (>3 months) were recruited from private chiropractic practice in Canada. Subjects completed a Neck Disability Index (NDI), Tampa Scale for Kinesiophobia (TSK), pain visual analog scale, and pain diagram. Clinical and demographic data were also obtained. Nine standard nonorganic pain behavior tests and 4 novel cervical nonorganic simulation signs (C-NOSS) tests were applied. Bivariate correlations were obtained with the Pearson correlation coefficient. Items achieving statistical significance on univariate analysis were loaded in a sequential linear regression analysis. Post hoc analyses were conducted with analysis of variance tests of NDI and TSK scores. RESULTS: Ninety-one subjects were investigated (49 males and 42 females), with a mean age of 41.7 (SD, 14.7) years and a mean duration of 9.4 (SD, 11.2) months. Because mean NDI scores were 57.5 (SD, 17.8) and mean pain scores were 68.3 (SD, 21.0), this sample represents moderate-to-severe WAD. Fair to moderately strong correlations were obtained between the NDI and the TSK, pain visual analog scale and nonorganic symptoms and signs (NOS-9) and C-NOSS scores, but not with "age," "sex," or "duration." The NOS-9 and C-NOSS scores correlated most strongly at 0.70. A multivariate model accounting for 53% of the variance of the NDI scores (P < .001) was obtained with the TSK, pain severity, and NOS-9 scores. There was no significant correlation between C-NOSS and TSK scores. At least 25% of subjects scored either 5 of 9 or 2 of 4 on the NOS-9 and C-NOSS tests, respectively. CONCLUSIONS: Based on the findings of this study, nonorganic signs should be considered in the interpretation of self-rated disability in patients with moderate-to-severe chronic WAD.

Is "fear of passive movement" a distinctive component of the Fear-Avoidance Model in whiplash?

OBJECTIVES: Modify the Tampa Scale for Kinesiophobia (TSK) for 'fear of passive motion' beliefs. METHODS: With permission, a 14-item modification, the TSK-PM (passive movement), was created. Test-retest reliability was tested first. Construct validity was tested in chronic whiplash patients by comparing the TSK-PM with the TSK, the Neck Disability Index (NDI) and cervical ranges of motion. RESULTS: The TSK-PM showed high test-retest reliability (r = 0.83) and high correlation with the original TSK (r = 0.84). Low, non-significant correlations were found with other variables. NDI scores were strongly correlated with ranges of motion. CONCLUSIONS: While having high test-retest reliability and a single factor structure, the TSK-PM failed to demonstrate distinctive construct validity vs the original TSK. The original TSK is likely to be sufficient to assess fear of being moved in neck pain patients in a clinical setting. Modifications to the current version of the TSK-PM might improve its construct validity in future studies.

OBJECTIFS: Modifier l'échelle de Tampa (TSK) pour l'évaluation de l'indice de kinésiophobie pour définir la « crainte du mouvement passif ¼. MÉTHODOLOGIE: Un questionnaire TSK-MP (mouvements passifs) a été créé en modifiant 14 points de la TSK avec permission. Tout d'abord, on a évalué la fiabilité de test-retest. La validité conceptuelle a été testée chez des patients souffrant d'entorse cervicale chronique en comparant le TSK-MP avec la TSK, l'indice d'incapacité cervicale (NDI) et les amplitudes de mouvement cervical. RÉSULTATS: Le TSK-MP a montré une grande fiabilité test-retest (r = 0,83) et une forte corrélation avec la TSK originale (r = 0,84). On a observé de faibles corrélations non significatives avec d'autres variables. Les résultats de l'indice d'incapacité cervicale étaient fortement corrélés avec les amplitudes de mouvement. CONCLUSIONS: Tout en ayant une haute fiabilité test-retest et une structure à un seul facteur, le TSK-MP n'a pas démontré une validité conceptuelle distincte par rapport à la TSK originale. La TSK originale est probablement suffisante pour évaluer la crainte d'être déplacé chez les patients atteints de douleurs cervicales dans un cadre clinique. Les modifications apportées à la version actuelle du TSK-MP pourraient améliorer sa validité conceptuelle dans des études futures.

Self-rated disability, fear-avoidance beliefs, nonorganic pain behaviors are important mediators of ranges of active motion in chronic whiplash patients.

PURPOSE: The influence of self-rated disability and fear-avoidance beliefs on whiplash sufferers in their performance of active ranges of motion has not been studied well. We undertook a cross-sectional study to determine this. METHODS: Chronic whiplash subjects completed a standard clinical examination. They completed the Neck Disability Index (NDI), the Tampa Scale for Kinesiophobia (TSK) and pain visual analog scale (VAS). Active ranges of motion (goniometer) and cervical nonorganic simulation signs (C-NOSS) were obtained by the examiner. Univariate and multivariable analyses were conducted on these scores. RESULTS: Sixty-four subjects (37 female) with a mean age of 41.4 (SD 16.1) years completed all scores. NDI, pain VAS and C-NOSS correlated significantly with ROM. In a multivariable model, only the NDI score contributed significantly to the variance of the ROM scores (14%). CONCLUSION: As chronic whiplash sufferers perform ROM in a clinical examination, these ranges are importantly influenced by their self-perceived disability. Cervical nonorganic simulation signs can be helpful in distinguishing high from very high levels of disability and motion restriction. The lack of correlation with the TSK may present a challenge to the Fear Avoidance Model in whiplash. Implications for Rehabilitation Self-ratings of disability in chronic whiplash sufferers are influenced by their fear-avoidance beliefs. While self-ratings of disability are known to predict chronicity of whiplash, there is less known about how these ratings affect impairment assessment during recovery. This study shows that self-ratings of disability influence the presentation of impairment by chronic whiplash sufferers with respect to their ranges of neck motion. Signs of nonorganic behavior also influence ranges of motion and self-ratings of disability. These findings should be incorporated into the interpretation of impairment findings in chronic whiplash sufferers in order to improve management.

Psychological factors in the use of the neck disability index in chronic whiplash patients.

STUDY DESIGN: Cross-sectional clinical study. OBJECTIVE: Determine if psychological factors "fear avoidance behavior" and "pain amplification," along with age, gender, duration, and pain severity correlate with scores of self-rated disability in chronic whiplash sufferers. SUMMARY OF BACKGROUND DATA: The Fear Avoidance Model has gained acceptance in the understanding of whiplash-associate disorders (WAD). While the variables important in this model have been studied in acute/subacute samples and some small chronic samples, no study has explicitly investigated the role these and other psychosocial variables play in the self-ratings of neck-related disability in chronic WAD sufferers. METHODS: Chronic WAD sufferers (>3 months) were recruited from private practice. No WAD IV subjects were included. Subjects completed a Neck Disability Index (NDI), Tampa Scale for Kinesiophobia (TSK), pain visual analogue scale, and pain diagram. Clinical and demographic data were also obtained. Univariate correlations were obtained with the Spearman rank correlation coefficient. Items achieving statistical significance on univariate analysis were loaded in a step-wise linear regression analysis. RESULTS: One hundred seven subjects were investigated (54 females), with a mean age of 45.4 (17) years and a mean duration of 13.4 (14.6) months. Fair to moderately strong correlations were obtained between the NDI and the TSK, pain visual analogue scale and pain drawing scores, but not with "duration." The Pain Diagram correlated with NDI scores and pain severity. A multivariate model accounting for 31% of the variance of the NDI scores (P < 0.001) was obtained with the TSK, pain severity, and pain drawing. CONCLUSION: It appears that important psychological factors (fear avoidance beliefs and pain amplification) do have some influence on self-ratings of disability in chronic WAD sufferers. This does not appear to be larger than that found in studies of acute/subacute subjects. The influence of these factors may plateau fairly early in the post-WAD period. There is some evidence that the Pain Diagram may provide insight into nonorganic pain behavior.

Assessing effects of a semi-customized experimental cervical pillow on symptomatic adults with chronic neck pain with and without headache.

OBJECTIVE: To determine the effects of a semi-customized experimental cervical pillow on symptomatic adults with chronic neck pain (with and without headache) during a four week study. DESIGN: A randomized controlled trial. SAMPLE SIZE: Thirty-six adults were recruited for the trial, and randomly assigned to experimental or non-experimental groups of 17 and 19 participants respectively. SUBJECTS: Adults with chronic biomechanical neck pain who were recruited from the Canadian Memorial Chiropractic College (CMCC) Walk-in Clinic. OUTCOME MEASURES: Subjective findings were assessed using a mail-in self-report daily pain diary, and the CMCC Neck Disability Index (NDI). STATISTICAL ANALYSIS: Using repeated measure analysis of variance weekly NDI scores, average weekly AM and PM pain scores between the experimental and non-experimental groups were compared throughout the study. RESULTS: The experimental group had statistically significant lower NDI scores (p < 0.05) than the non-experimental group. The average weekly AM scores were lower and statistically significant (p < 0.05) in the experimental group. The PM scores in the experimental group were lower but not statistically significant than the other group. CONCLUSIONS: The study results show that compared to conventional pillows, this experimental semi-customized cervical pillow was effective in reducing low-level neck pain intensity, especially in the morning following its use in a 4 week long study.