A microfabricated low-profile wideband antenna array for terahertz communications.

While terahertz communications are considered to be the future solutions for the increasing demands on bandwidth, terahertz equivalents of radio frequency front-end components have not been realized. It remains challenging to achieve wideband, low profile antenna arrays with highly directive beams of radiation. Here, based on the complementary antenna approach, a wideband 2 × 2 cavity-backed slot antenna array with a corrugated surface is proposed. The approach is based on a unidirectional antenna with a cardiac radiation pattern and stable frequency characteristics that is achieved by integrating a series-resonant electric dipole with a parallel-resonant magnetic dipole. In this design, the slots work as magnetic dipoles while the corrugated surface radiates as an array of electric dipoles. The proposed antenna is realized at 1 THz operating frequency by stacking multiple metallized layers using the microfabrication technology. S-parameter measurements of this terahertz low-profile metallic antenna array demonstrate high efficiency at terahertz frequencies. Fractional bandwidth and gain are measured to be 26% and 14 dBi which are consistent with the simulated results. The proposed antenna can be used as the building block for larger antenna arrays with more directive beams, paving the way to develop high gain low-profile antennas for future communication needs.

Anthropometry of the patellar tendon in Chinese.

PURPOSE: To assess the length of the patellar tendon in Chinese and its correlation with patient age, gender, and operated side. METHODS: 109 men and 11 women aged 15 to 45 (mean, 25) years underwent arthroscopic bone-tendon-bone reconstruction for anterior cruciate ligament (ACL) insufficiency. 55 (46%) injured the left side, and 65 (54%) the right side. Each patient's age, gender, and operated side were recorded. The length of the patellar tendon harvested was measured. RESULTS: The mean length of the patellar tendon graft was 42.6 (standard deviation, 4.6; range, 30-54) mm. There was no correlation between the length of the patellar tendon and patient's age (p=0.147), gender (p=0.076), or operated side (p=0.466). CONCLUSION: The length of the patellar tendon in the Chinese is comparable to that in Caucasians. Because of the shorter ACL but similar patellar tendon length, graft-tunnel mismatch may be more common in Chinese than Caucasian patients.

The onset of eruption of permanent teeth amongst South African Indian children.

A total of 1036 Indian children were examined to determine the mean ages of eruption for the first permanent molars, and the permanent central and lateral incisors. The youngest observed age for the eruption of any permanent tooth was 5.00 years for girls and 4.94 for boys. Mandibular teeth erupted earlier than maxillary teeth and teeth in females erupted between 1 and 6 months earlier than in males. Comparison of the results of the present study to one in South African black children showed that Indian children's teeth erupt some 3.5-7 months later than those of black children, a difference that was statistically significant.

The onset of eruption of the permanent dentition amongst South African black children.

One thousand and twenty-four children with a mean age of 6.41 yr were examined to determine the mean ages of eruption for the first permanent molars and the permanent central and lateral incisors. The youngest observed age for the eruption of any permanent tooth amongst girls was 4.50 yr and amongst boys, 4.31 yr. The eruption ages were on the whole later than those reported in most African studies, but were very similar to those found for Kenyan African and American blacks.