Field Decorrelation and Isolation Improvement in an MIMO Antenna Using an All-Dielectric Device Based on Transformation Electromagnetics.

This work presents a new technique for enhancing the performance of a multiple-input multiple-output (MIMO) antenna by improving its correlation coefficient ρ. A broadband dielectric structure is designed using the transformation electromagnetics (TE) concept to decorrelate the fields of closely placed radiating elements of an MIMO antenna, thereby decreasing ρ and mutual coupling. The desired properties of the broadband dielectric wave tilting structure (DWTS) are determined by using quasi-conformal transformation electromagnetics (QCTE). Next, the permittivity profile of the DWTS is realized by employing air-hole technology, which is based on the effective medium theory, and the DWTS is fabricated using the additive manufacturing (3D printing) technique. The effectiveness of the proposed technique is verified by designing two-element patch-based MIMO antenna prototypes operating at 3 GHz, 5 GHz, and 7 GHz, respectively. The proposed technique helped to reduce the correlation coefficient ρ in the range of 37% to 99% in the respective operating bandwidth of each MIMO antenna, thereby, in each case, improving the isolation between antenna elements by better than 3 dB, which is an excellent performance.

Post-treatment cephalometric changes in adolescent patients with Class II malocclusion treated using two different functional appliance systems for an extended time period: a randomized clinical trial.

OBJECTIVES: To assess the post-treatment changes in Class II adolescent patients treated with two different functional appliances for an extended time period. DESIGN: Randomized clinical trial. SETTING: One university and one district general hospital in the UK. PARTICIPANTS: Caucasian adolescent patients with a Class II malocclusion. METHODS: Pairs of patients of similar age and gender were randomly allocated to one of two functional appliance systems, the Twin Block or Dynamax appliance. The appliances were used for 15 months full time. Changes were measured from lateral cephalograms taken at the start (T1) and at the end of treatment at 15 months (T2) and 30 months (T3). RESULTS: Hundred patients completed the trial, 52 Twin Block and 48 Dynamax. Mandibular forward movement was 3.5 mm (±2.5) in the Twin Block group and 1.7 mm (±2.1) in the Dynamax group (P < 0.01; T1-T2) and, subsequently, by 0.3 mm (±2.6) and 0.9 mm (±2.5), respectively (P = 0.3; T2-T3). Mandibular length increased by 6.3 mm (±2.7) in the Twin Block group and 4.0 mm (±2.5) in the Dynamax group (P < 0.01; T1-T2) with treatment and, subsequently, by 0.5 mm (±2.3) and 1.5 mm (±3.1; P = 0.05). Anterior face height increased in both groups. CONCLUSIONS: Treatment resulted in greater mandibular growth with the Twin Block than the Dynamax. In the follow-up period, there was less growth in the Twin Block group compared to the Dynamax. TRIAL REGISTRATION: This trial was not registered on any major database of clinical trial. PROTOCOL: The protocol was not published before the commencement of the trial but can be given on request.

Diagnostic Accuracy of Peritoneal Fluid GeneXpert in the Diagnosis of Intestinal Tuberculosis, Keeping Histopathology as the Gold Standard.

Background The diagnosis of abdominal tuberculosis is a major health challenge. Limited data are available to support the use of GeneXpert MTB/RIF in the diagnosis of abdominal tuberculosis. The current study is an analysis of the sensitivity and specificity of GeneXpert MTB/RIF for the diagnosis of abdominal tuberculosis, keeping histopathology as the gold standard. Materials and methods A prospective study was conducted in Surgery Unit-I of Holy Family hospital in the year 2017. Data of 21 patients presenting with abdominal tuberculosis were collected. The samples collected were ascitic fluid for GeneXpert and acid-fast bacilli (AFB) and a tissue sample for histopathology, which included either the enlarged lymph nodes or the involved gut segment. Results Out of a total of 21 patients, 10 were male and 11 were female. The predominant age group was less than 30 years with 76.2% cases. Of the 21 samples analyzed, all were positive for tuberculosis (TB) by histopathology. GeneXpert was positive in six and negative in 15 patients. The sensitivity of GeneXpert was 28.57% and specificity was 0%. The positive predictive value was 100%. The diagnostic accuracy was found to be 28.57%. Conclusion In our study, GeneXpert has shown poor sensitivity and specificity for the detection of abdominal TB from ascitic fluid samples. On the basis of this data, we lay stress on finding new tests and biomarkers for the rapid diagnosis of abdominal TB.

Pain experience in adults undergoing treatment: A longitudinal evaluation.

OBJECTIVES: To quantify the intensity and duration of pain experience in adults over the initial three visits of fixed appliance-based orthodontic treatment. A secondary objective was to assess the relationship between pain experience and analgesic use, dental irregularity, gender, and age. MATERIALS AND METHODS: A prospective longitudinal study design was adopted. Fifty-eight adults undergoing fixed appliance treatment in five orthodontic practices recorded pain experience at four time points (4 hours, 24 hours, 3 days, and 7 days) following the initial bond-up appointment (T0) and first (T1) and second (T2) routine follow-up adjustment appointments using a visual analogue scale. In addition, subjects recorded the dosage and frequency of analgesic use. RESULTS: A slightly greater proportion of women (57%) were recruited, with a mean sample age of 34.69 (SD 12.11) years. Peak pain was experienced between 24 hours and 3 days following appliance placement (T0) and subsequent adjustments (T1 and T2). The highest mean pain score arose at T0 followed by T2 and T1 adjustments, with the difference between pain levels at these appointment intervals being statistically significant ( P < .001). The use of analgesics following each appointment mirrored pain experience, with pain score, appointment, and time point all being significant predictors of analgesic consumption. The level of dental irregularity, gender, or age did not predict pain levels reported. CONCLUSIONS: Adults undergoing fixed orthodontic therapy should be advised that they are most likely to experience increased levels of pain for 1 to 3 days following placement of their appliance and subsequent adjustment visits.

Isolated Duodenal Injuries After Blunt Abdominal Trauma.

Isolated duodenal injury after blunt abdominal trauma is a very rare entity. In contrast to penetrating injuries, duodenal injuries after blunt trauma are difficult to diagnose. Early diagnosis and management is required to prevent high morbidity and mortality associated with these injuries. We present three young patients of blunt abdominal trauma with an isolated injury to duodenum in which primary repair of perforations were done with good outcomes.

An extended period of functional appliance therapy: a controlled clinical trial comparing the Twin Block and Dynamax appliances.

The aim of this clinical trial was to compare the hard- and soft-tissue effects of 15 month full-time functional appliance therapy with Twin Block (TB) and Dynamax (Dx) appliances. The effects on both hard and soft tissue were analysed using cephalograms and three-dimensional optical surface laser scans. One hundred and three subjects with a class II division 1 malocclusion, and a minimum overjet of 7mm were available for analysis following stratified randomization according to gender and age. Data was collected at the start of treatment, 15 month therapy, and after 3 month post-treatment observation. Statistical analysis was conducted using analysis of covariance. The results demonstrated both appliances corrected the overjet with significantly increased skeletal dimensional changes with the TB compared with the Dx with forward movement of pogonion of 5.2mm (TB) and 0.7mm (Dx) P = 0.003. In addition, significant changes occurred particularly in the vertical dimension where there was also an increase in total anterior face height in both groups (TB = 6.4mm, Dx = 5.5mm) and significant (P = 0.003) mandibular length changes were also observed (TB = 7.2mm, Dx = 3.8mm). The cephalometric soft-tissue changes were significantly different between the two appliances at soft-tissue pogonion (TB = 9.8mm, Dx = 4.6mm, P = 0.001). Laser scan three-dimansional changes showed significant difference in the lower labial sulcus region where forward movements were observed (TB = 8.2mm, Dx = 6.2mm; P = 0.04). Overall these changes appear to be greater and more stable than those achieved in a previous 9 month study.

An investigation of cephalometric and morphological predictors of successful twin block therapy.

OBJECTIVE: To identify predictors of overjet reduction, changes in mandibular length (Co-Me) and antero-posterior changes in mandibular position (Pog-Vert) during Twin Block therapy. METHODS: Pre- and post-treatment cephalograms of 131 participants were analysed (Mean age 12.73 years +/- 1) following Twin Block therapy. RESULTS: Mean annualised overjet reduction was 7.29 mm (+/- 2.99) with chin projection improving by 2.66 mm (+/- 5.37). The magnitude of the initial overjet was a strong predictor (95% CI: 0.30, 0.77, p < 0.01) of overjet reduction and change in chin position (95% CI: 0.08, 0.77, p = 0.02). Greater forward movement of Pogonion occurred if there was greater retrusion of Pogonion at the outset (95% CI: 0.15, 0.45, p < 0.01). No prognostic relationship was noted for other potential cephalometric predictors including pretreatment mandibular lower border morphology and Co-Go-Me angle. CONCLUSION: No relationship between mandibular morphology, vertical skeletal pattern and favourable dentoalveolar and skeletal responses to Twin Block therapy could be found. These results require confirmation on an external sample.

Role of nasogastric intubation after small bowel anastomosis.

OBJECTIVE: To determine advantages and disadvantages of postoperative nasogastric intubation after small bowel anastomosis. STUDY DESIGN: Quasi experimental. PLACE AND DURATION OF STUDY: Surgical Unit-I, Holy Family Hospital, Rawalpindi, from December 2003 to December 2006. METHODOLOGY: A total of 112 patients, undergoing small bowel anastomosis were equally divided in group I and II with and without postoperative nasogastric intubation respectively. Variables compared were number of patients having episodes of vomiting, change in abdominal girth, the time for onset of bowel sounds, time to begin per oral fluids, length of hospitalization and postoperative complications. RESULTS: In group-I, nasogastric tube was removed on an average after 3.1 days. Average postoperative nasogastric output was 357, 154 and 64 ml/day for day 1, 2 and 3 respectively. There was no statistically significant difference between two groups in abdominal girth before and after operation, frequency of vomiting, time taken for onset of bowel sounds and start of oral sips after operation, frequency of wound infection, anastomotic leak and mortality (p>0.05). Length of postoperative hospital stay and frequency of postoperative respiratory complications were more in group-I as compared to group-II (p<0.05). CONCLUSION: Nasogastric decompression does not provide added advantage after small bowel anastomosis.