Disorder and defect formation mechanisms in molecular-beam-epitaxy grown silicon epilayers

We investigate the role of disorder, stress and crystallite size in determining the density of defects in disordered and partially ordered silicon thin films deposited at low or moderate temperatures by molecular beam epitaxy. We find that the paramagnetic defect density measured by electron spin resonance (ESR) is strongly dependent on the growth temperature of the films, decreasing from ~ 2\ub71019 cm- 3 at 98 C to ~ 1\ub710 18 cm- 3 at 572 C. The physical nature of the defects is strongly dependent on the range of order in the films: ESR spectra consistent with dangling bonds in an amorphous phase are observed at the lowest temperatures, while the ESR signal gradually becomes more anisotropic as medium-range order improves and the stress level (measured both by X-ray diffraction and Raman spectroscopy) is released in more crystalline films. Anisotropic ESR spectra consistent with paramagnetic defects embedded in an epitaxial phase are observed at the highest growth temperature (572 C).Peer reviewed: YesNRC publication: Ye

Ultrasound detection of placenta accreta in the first trimester of pregnancy

Background: Placenta accreta is considered a life-threatening condition and the main cause of maternal mortality. Prenatal diagnosis of placenta accreta usually is made by clinical presentation, imaging studies like ultrasound and MRI in the second and third trimester. Objective: To determine accuracy of ultrasound findings for placenta accreta in the first trimester of pregnancy. Materials and Methods: In a longitudinal study 323 high risk patients for placenta accreta were assessed. The eligible women were examined by vaginal and abdominal ultrasound for gestational sac and placental localization and they were followed up until the end of pregnancy. The ultrasound findings were compared with histopathological examinations as a gold standard. The sensitivity, specificity, positive and negative predictive value of ultrasound were estimated for the first trimester and compared with other 2 trimesters in the case of repeated ultrasound examination. Results: Ultrasound examinations in the first trimester revealed that 28 cases had the findings in favor of placenta accreta which ultimately was confirmed in 7 cases. The ultrasound sensitivity and specificity for detecting placenta accreta in the first trimester was 41 95% CI: 16.2-62.7 and 88% 95% CI: 88.2-94.6 respectively. Conclusion: Ultrasound screening for placenta accreta in the first trimester of pregnancy could not achieve the high sensitivity as second and third trimester of pregnancy. © 2014, Research and Clinical Center for Infertitlity. All Rights reserved

Introducing the LBT Imaging of Galactic Halos and Tidal Structures (LIGHTS) survey: A preview of the low surface brightness Universe to be unveiled by LSST

We present the first results of the LBT Imaging of Galaxy Haloes and Tidal Structures (LIGHTS) survey. LIGHTS is an ongoing observational campaign with the 2 × 8.4 m Large Binocular Telescope (LBT) aiming to explore the stellar haloes and the low surface brightness population of satellites down to a depth of μV ∼31 mag arcsec-2 (3σ in 10″ × 10″ boxes) of nearby galaxies. We simultaneously collected deep imaging in the g and r Sloan filters using the Large Binocular Cameras. The resulting images are 60 times (i.e. ∼4.5 mag) deeper than those from the Sloan Digital Sky Survey, and they have characteristics comparable (in depth and spatial resolution) to the ones expected from the future Legacy Survey of Space and Time (LSST). Here we show the first results of our pilot programme targeting NGC 1042 (an M 33 analogue at a distance of 13.5 Mpc) and its surroundings. The depth of the images allowed us to detect an asymmetric stellar halo in the outskirts of this galaxy whose mass (1.4 ± 0.4 × 108 M) is in agreement with the ΛCDM expectations. Additionally, we show that deep imaging from the LBT reveals low mass satellites (a few times 105 M) with very faint central surface brightness μV(0) ∼27 mag arcsec-2 (i.e. similar to Local Group dwarf spheroidals, such as Andromeda XIV or Sextans, but at distances well beyond the local volume). The depth and spatial resolution provided by the LIGHTS survey open up a unique opportunity to explore the 'missing satellites' problem in a large variety of galaxies beyond our Local Group down to masses where the difference between the theory and observation (if any) should be significant

Chronic Kidney Disease in Iran: First Report of the National Registry in Children and Adolescences

Purpose: Knowing the epidemiological aspects of chronic kidney disease (CKD) in children is crucial for early recognition, identification of reversible causes, and prognosis. Here, we report the epidemiological characteristics of childhood CKD in Iran. Materials and Methods: This cross-sectional study was conducted during 1991 � 2009. The data were collected using the information in the Iranian Pediatric Registry of Chronic Kidney Disease (IPRCKD) core dataset. Results: A total of 1247 children were registered. The mean age of the children at registration was 0.69 ± 4.72 years (range, 0.25 �18 years), 7.79 ± 3.18 years for hemodialysis (HD), 4.24 ± 1.86 years for continuous ambulatory peritoneal dialysis (CAPD), and 3.4±1.95 years for the children who underwent the renal transplantation (RT) (P < .001). The mean year of follow-up was 7.19 ± 4.65 years. The mean annual incidence of CKD 2�5 stages was 3.34 per million age-related population (pmarp). The mean prevalence of CKD 2�5 stages was 21.95 (pmarp). The cumulative 1-, 5-, and 10-year patients� survival rates were 98.3, 90.7, and 84.8, respectively. The etiology of the CKD included the congenital anomalies of the kidney and urinary tract (CAKUT) (40.01), glomerulopathy (19.00), unknown cause (18.28), and cystic/hereditary/congenital disease (11.14). Conclusion: The incidence and prevalence rate of pediatric CKD in Iran is relatively lower than those reported in Europe and other similar studies. CAKUT was the main cause of the CKD. Appropriate management of CAKUT including early urological intervention is required to preserve the renal function. Herein, the long-term survival rate was higher among the children with CKD than the literature. © 2021. All Rights Reserved