Calibration to Mitigate Near-Field Antennas Effects for a MIMO Radar Imaging System.

A calibration method for a high-resolution hybrid MIMO turntable radar imaging system is presented. A line of small metal spheres is employed as a test pattern in the calibration process to measure the position shift caused by undesired antenna effects. The unwanted effects in the antenna near-field responses are analysed, modelled and significantly mitigated based on the symmetry and differences in the responses of the MIMO configuration.

A Wide Frequency Scanning Printed Bruce Array Antenna with Bowtie and Semi-Circular Elements.

A printed edge-fed counterpart of the wire Bruce array antenna, for frequency scanning applications, is presented in this paper. The unit-cell of the proposed antenna consists of bowtie and semi-circular elements to achieve wide bandwidth from below 22 GHz to above 38 GHz with open-stopband suppression. The open-stopband suppression enables a wide seamless scanning range from backward, through broadside, to forward endfire. A sidelobe threshold level of -10 dB is maintained to evaluate efficient scanning performance of the antenna. The antenna peak realized gain is 15.30 dBi, and, due to its compact size, has the ability to scan from -64° to 76°.

Mobile phone 'talk-mode' signal delays EEG-determined sleep onset.

Mobile phones signals are pulse-modulated microwaves, and EEG studies suggest that the extremely low-frequency (ELF) pulse modulation has sleep effects. However, 'talk', 'listen' and 'standby' modes differ in the ELF (2, 8, and 217Hz) spectral components and specific absorption rates, but no sleep study has differentiated these modes. We used a GSM900 mobile phone controlled by a base-station simulator and a test SIM card to simulate these three specific modes, transmitted at 12.5% (23dBm) of maximum power. At weekly intervals, 10 healthy young adults, sleep restricted to 6h, were randomly and single-blind exposed to one of: talk, listen, standby and sham (nil signal) modes, for 30 min, at 13:30 h, whilst lying in a sound-proof, lit bedroom, with a thermally insulated silent phone beside the right ear. Bipolar EEGs were recorded continuously, and subjective ratings of sleepiness obtained every 3 min (before, during and after exposure). After exposure the phone and base-station were switched off, the bedroom darkened, and a 90 min sleep opportunity followed. We report on sleep onset using: (i) visually scored latency to onset of stage 2 sleep, (ii) EEG power spectral analysis. There was no condition effect for subjective sleepiness. Post-exposure, sleep latency after talk mode was markedly and significantly delayed beyond listen and sham modes. This condition effect over time was also quite evident in 1-4Hz EEG frontal power, which is a frequency range particularly sensitive to sleep onset. It is possible that 2, 8, 217Hz modulation may differentially affect sleep onset.

Safety and donor acceptance of an abbreviated donor history questionnaire.

BACKGROUND: Surveys have shown donor dissatisfaction with the duration of the donation process and repetitive questioning. An abbreviated donor history questionnaire (AQ) may improve satisfaction, but must be safe. STUDY DESIGN AND METHODS: An FDA-approved 34-question AQ was implemented in 2003. Travel, medication, and health history questions were decreased by 18. Donors were eligible for AQ if they had successfully completed three donor suitability assessments on the full-length questionnaire (FQ), including one in the prior 6 months. Data were analyzed from more than 50,000 donations during each of three 20-day periods over the first year of progressive implementation of the AQ. We evaluated the performance of the AQ by comparing donor deferrals for medical history (MHD), physical examination findings (PED), and reactive screening and/or confirmatory tests (RSCT) for viral markers among AQ-ineligible and AQ-eligible donors and separately among AQ-eligible donors who received AQ or FQ. RESULTS: Approximately one-third of presenting donors were AQ-eligible. Use of AQ progressed from 48 percent in October 2003 to 76 percent in November 2004. AQ-eligible donors had lower rates of MHD, PED, and RSCT than donors ineligible for AQ (p < 0.05). Among donors eligible for the AQ, those who received the FQ had slightly more MHD and PED than those who received the AQ (p < 0.05), but there was no difference in RSCT. A postdonation survey indicated significantly increased satisfaction and intent to donate among donors who received the AQ. CONCLUSIONS: In frequent repeat donors, use of an AQ led to increased donor satisfaction and no significant medical concerns about donor or recipient safety.

A randomized trial of blood donor recruitment strategies.

BACKGROUND: Improvement in donor return rates, especially among first-time donors, may significantly improve the blood supply. There are few rigorous studies of the effectiveness of various approaches to donor recruitment, however. STUDY DESIGN AND METHODS: By use of a single-blind, randomized trial design, 6919 post-September 11, 2001, first-time donors were randomly assigned into the following intervention arms: T-shirt incentive versus none, recruitment scripts with a patient story (Script A) versus a complimentary message including the donor's blood type (Script B), and telephone versus e-mail recruitment. Our primary outcome was a second donation within 6 months. Rate ratios (RRs) and 95 percent confidence intervals (95% CIs) were calculated with Taylor series methods. RESULTS: A total of 1421 (20.5%) first-time donors returned within the 6 months, including 1252 with a second and 169 with both second and third donations. The T-shirt incentive was not effective in increasing returns compared to no incentive (20.5% vs. 20.6%; RR, 0.99; 95% CI, 0.91-1.09). Script A was significantly more effective than Script B (22.2% vs. 18.9%; RR, 1.18; 95% CI, 1.07-1.29). E-mail was substantially less effective than telephone recruitment (13.2% vs. 27.8%; RR, 0.48; 95% CI, 0.40-0.57). CONCLUSIONS: A T-shirt incentive had no apparent effect, but an empathetic message significantly improved the return donation rate. E-mail recruitment was substantially less effective than telephone recruitment, perhaps due to technical problems. The study illustrates the utility of the randomized clinical trial study design for testing donor recruitment strategies.

Triggers for switching from minipool testing by nucleic acid technology to individual-donation nucleic acid testing for West Nile virus: analysis of 2003 data to inform 2004 decision making.

BACKGROUND: Concern about West Nile virus (WNV) transfusion-transmitted infections missed by minipool (MP) nucleic acid testing (NAT) has prompted consideration of the use of individual-donation (ID) NAT. Strategies were investigated for the application of limited ID-NAT capacity in 2004. STUDY DESIGN AND METHODS: Patterns of WNV MP-NAT-reactive donations tested by the Blood Systems Laboratory each week for 79 blood centers from June 29 to November 23, 2003 (196 MP-NAT repeat-reactive [RR] donations among 801,697 units), were analyzed. ID-NAT initiation strategies were developed consisting of counts of RR donations and/or weekly RR rates, together with three ID-NAT discontinuation strategies, and ID testing burden was assessed based on these combined start and stop strategies. RESULTS: The effectiveness, reported as the percentage of MP-RR donations that would trigger ID-NAT based on each initiation strategy, ranged from 57 to 100 percent. The addition of a 1- or 2-week no-yield requirement for ID discontinuation substantially increased testing burden. Combined strategies resulted in projected ID-NAT of between 10 and 50 percent of donations for a 10- to 20-week period. For this organization, the most feasible ID-NAT initiation strategy was 2 MP-reactive donations and a weekly rate of 1 in 1000, which had an effectiveness of 81 percent and led to peak weekly ID-NAT of 20 to 25 percent of donations depending on the discontinuation rule. CONCLUSION: This new approach of targeted ID-NAT based on ongoing monitoring of MP-NAT yield may prove to be a rational policy for agents like WNV that cause seasonal and regional epidemics.

Estimating blood donor loss due to the variant CJD travel deferral.

BACKGROUND: The FDA recommended new travel deferrals in May 2002 to prevent the potential transmission of variant CJD (vCJD). The predicted impact of such deferrals on the blood supply was controversial. STUDY DESIGN AND METHODS: We distributed anonymous, self-administered questionnaires to donors over 2 weeks in April 2002. Two thousand surveys were allocated to each of five geographic groupings of blood centers in the western and central US. Results were analyzed with chi-squared tests and logistic regression. RESULTS: Of 9800 surveys, 7405 (76%) were returned and analyzed. Overall, 257 (3.47%; 95% CI, 3.05-3.89) donors responding to the survey met the expanded May and November 2002 FDA vCJD travel criteria for deferral. Deferral rates ranged from 1 percent or less in Northern and Southern centers, 3 to 4 percent in San Francisco, California, and Scottsdale, Arizona, to over 13 percent in El Paso, Texas (p < 0.0001). Service at a European military base was the most common reason for deferral, whereas in San Francisco most deferrals were for UK and European travel or residence. The vCJD deferral was also associated with ages 30 through 49 years and with male gender. During June through September 2002, observed deferral rates were 1.6 percent at the same centers. CONCLUSIONS: Predicted deferrals due the new vCJD travel criteria depend upon the number of military donors at a blood center, as well as on the age and gender of donors. Actual deferrals were lower than predicted by an anonymous survey.

Selecting treatment options and sequencing treatment in the replacement of 2 maxillary central incisors with implants: a case report.

This article describes treatment provided to replace 2 maxillary central incisors with implant-supported restorations. The site of a missing maxillary central incisor was treated utilizing a bone expansion technique to augment the labial hard and soft-tissue profiles at the time of implant placement. The adjacent central incisor tooth, although destined to be extracted, was retained to serve as an abutment for a fixed provisional restoration until the first implant was deemed to have successfully integrated. At the appointment to uncover this implant, the fractured tooth was extracted and an implant was immediately placed into the socket. The first implant was then used to support the provisional restoration during the healing phase of the second implant. The techniques utilized resulted in optimum soft-tissue contours, allowed the patient to have a comfortable and esthetic provisional restoration, and minimized the number of surgical procedures.