ABSTRACT
Over the recent years, reflectarrays and transmitarrays have been drawing a considerable attention due to their attractive features, including a possibility of realizing high gain and pencil-like radiation patterns without the employment of complex feeding networks. Among the two, transmitarrays seem to be superior over reflectarrays in terms of achieving high radiation efficiency without the feed blockage. Notwithstanding, the design process of transmitarrays is more intricate due to the necessity of manipulating both the transmission phase and magnitude of its unit elements. For reliability, the design process has to be conducted at the level of full-wave electromagnetic models, which makes direct optimization prohibitive. The most widely used workaround is to employ surrogate modeling techniques to construct fast representations of the unit elements, yet the initial model setup cost is typically high and includes acquisition of thousands of training data points. In this paper, we propose a novel approach to cost-efficient design of transmitarrays. It is based on artificial-intelligence-enabled data-driven surrogates, which can be constructed using only a few hundreds of training data samples, while exhibiting the predictive power sufficient for reliable design. Our methodology is demonstrated by re-using the presented surrogate for the design of high-performance transmitarrays operating at various frequency ranges of 8-14 GHz, 22-28 GHz, and 28-36 GHz.
ABSTRACT
This study aimed to investigate the coexistence of pilonidal sinus disease (PSD) and hirsutism in female patients. Materials and methods: The demographic and clinical data of 164 female patients who underwent surgery for PSD between January 2007 and May 2014 were evaluated for this retrospective cross-sectional study. Data collected for this study were age, BMI, the modified Ferriman and Gallwey scale (mFGS) for hirsutism, main symptoms, type of surgery, early postoperative complications (wound infection, wound dehiscence), recurrence, and follow-up. The independent variables are hirsutism (mFGS scores) and BMI. Dependent variables are early postoperative complications and recurrence. Results: The median age was 20 years (95% CI for median: 19-21 years). According to the BMI, 45.7, 50.6, and 3.7% of patients were considered normal, overweight, and obese, respectively. According to the mFGS, 11, 9.8, 52.4, and 26.8% of patients were considered to have none, mild, moderate, or severe hirsutism, respectively. Fourteen (8.5%) patients had developed recurrence. Recurrence developed in six patients with primary closure, five patients with Limberg flaps, two patients with Karydakis, and one with marsupialization. There was no statistical difference between recurrent and nonrecurrent patients in terms of BMI (P=0.054) and mFGS (P=0.921). On the other hand, BMI was statistically significantly higher in those who developed early postoperative complications than in those who did not (P<0.001). Conclusion: PSD is no longer a 'men's only disease'. BMI increases the risk of early postoperative complications, but this association was not found between BMI and recurrence. Prospective multicenter studies are needed on the relationship between PSD and hirsutism.
ABSTRACT
BACKGROUND: Situs inversus (SI) and midgut malrotation (MM) are uncommon anatomic anomalies that complicate diagnosis and management of acute abdominal pain. METHODS: We present two cases of left-sided acute appendicitis with situs inversus totalis and a literature review of studies published in English language on left-sided acute appendicitis, accessed via Pubmed and Google Scholar database. RESULTS: Sixty-three published cases of left-sided acute appendicitis were evaluated, and two patients (M:16 yr, F:17 yr) who presented to our clinic with left lower quadrant pain caused by left-sided acute appendicitis were reported. Thirty-five of the patients were male and 30 were female (including our patients) with age range from 8 to 63 years and median age of 26.7 +/- 14.0 years. Fifty-three patients had situs inversus totalis (SIT), 8 had MM and two were with malrotation of the caecum. Thirty-eight patients had applied to the hospital with left lower quadrant pain, 12 with right and 6 with bilateral lower quadrant pain. Thirty patients were diagnosed as having SIT or MM, while the diagnosis in 12 patients was established during the intraoperative period. Eleven patients with SIT were aware of having this anomaly. Five of the patients underwent laparoscopic appendectomy and in two patients laparoscopic appendectomy and cholecystectomy were performed in one session. Preoperative diagnosis has been easier to achieve after 1985, when ultrasonography (USG) and computed tomography (CT) were introduced into the medical practice. CONCLUSION: SIT and MM should be taken into consideration in patients with findings of the physical examination suspicious for left-sided acute appendicitis. X-ray, USG, CT and diagnostic laparoscopy are beneficial in developing the differential diagnosis.