Structural and Optical Properties of Diluted Magnetic Ga1−xMnxAs–AlAs Quantum Wells Grown on High-Index GaAs Planes

We report on the structural and optical properties of Ga₁₋ᵪ Mn ᵪ As-AlAs quantum wells (QWs) with χ=0.1% grown by molecular beam epitaxy (MBE) on semi-insulating GaAs substrates with orientations (100), (110), (311)B and (411)B. Atomic force microscopy (AFM), X-ray diffraction (XRD) and photoluminescence (PL) techniques were used to investigate these QWs. AFM results have evidenced the formation of Mn-induced islands, which are randomly distributed on the surface. These islands tend to segregate for samples grown on (110) and (411)B planes, while no clear segregation was observed for samples grown on (100) and (311)B orientations. Results show that the PL line width increases with Mn segregation. XRD measurements were used to determine 2θ,d and cell parameters

Ferromagnetic Semiconductors: Moving Beyond (Ga,Mn)As

The recent development of MBE techniques for growth of III-V ferromagnetic semiconductors has created materials with exceptional promise in spintronics, i.e. electronics that exploit carrier spin polarization. Among the most carefully studied of these materials is (Ga,Mn)As, in which meticulous optimization of growth techniques has led to reproducible materials properties and ferromagnetic transition temperatures well above 150 K. We review progress in the understanding of this particular material and efforts to address ferromagnetic semiconductors as a class. We then discuss proposals for how these materials might find applications in spintronics. Finally, we propose criteria that can be used to judge the potential utility of newly discovered ferromagnetic semiconductors, and we suggest guidelines that may be helpful in shaping the search for the ideal material.Comment: 37 pages, 4 figure

Distance decay in delivery care utilisation associated with neonatal mortality. A case referent study in northern Vietnam

BACKGROUND: Efforts to reduce neonatal mortality are essential if the Millennium Development Goal (MDG) 4 is to be met. The impact of spatial dimensions of neonatal survival has not been thoroughly investigated even though access to good quality delivery care is considered to be one of the main priorities when trying to reduce neonatal mortality. This study examined the association between distance from the mother's home to the closest health facility and neonatal mortality, and investigated the influence of distance on patterns of perinatal health care utilisation. METHODS: A surveillance system of live births and neonatal deaths was set up in eight districts of Quang Ninh province, Vietnam, from July 2008 to December 2009. Case referent design including all neonatal deaths and randomly selected newborn referents from the same population. Interviews were performed with mothers of all subjects and GIS coordinates for mothers' homes and all health facilities in the study area were obtained. Straight-line distances were calculated using ArcGIS software. RESULTS: A total of 197 neonatal deaths and 11 708 births were registered and 686 referents selected. Health care utilisation prior to and at delivery varied with distance to the health facility. Mothers living farthest away (4th and 5th quintile, ≥1257 meters) from a health facility had an increased risk of neonatal mortality (OR 1.96, 95% CI 1.40 - 2.75, adjusted for maternal age at delivery and marital status). When stratified for socio-economic factors there was an increased risk for neonatal mortality for mothers with low education and from poor households who lived farther away from a health facility. Mothers who delivered at home had more than twice as long to a health facility compared to mothers who delivered at a health care facility. There was no difference in age at death when comparing neonates born at home or health facility deliveries (p = 0.56). CONCLUSION: Distance to the closest health facility was negatively associated with neonatal mortality risk. Health care utilisation in the prenatal period could partly explain this risk elevation since there was a distance decay in health system usage prior to and at delivery. The geographical dimension must be taken into consideration when planning interventions for improved neonatal survival, especially when targeting socio-economically disadvantaged groups

Nonvolatile ferroelectric control of ferromagnetism in (Ga,Mn)As

There is currently much interest in materials and structures that provide coupled ferroelectric and ferromagnetic responses, with a long-term goal of developing new memories and spintronic logic elements. Within the field there is a focus on composites coupled by magnetostrictive and piezoelectric strain transmitted across ferromagnetic-ferroelectric interfaces, but substrate clamping limits the response in the supported multilayer configuration favoured for devices. This constraint is avoided in a ferroelectric-ferromagnetic bilayer in which the magnetic response is modulated by the electric field of the poled ferroelectric. Here, we report the realization of such a device using a diluted magnetic semiconductor (DMS) channel and a polymer ferroelectric gate. Polarization reversal of the gate by a single voltage pulse results in a persistent modulation of the Curie temperature as large as 5%. The device demonstrates direct and quantitatively understood electric-fieldmediated coupling in a multiferroic bilayer and may provide new routes to nanostructured DMS materials and devices via ferroelectric domain nanopatterning. The successful implementation of a polymer-ferroelectric gate fieldeffect transistor (FeFET) with a DMS channel adds a new functionality to semiconductor spintronics and may be of importance for future low-voltage spintronics devices and memory structures.Comment: 19 pages, 5 figure

Global, regional, and national burden of disorders affecting the nervous system, 1990–2021: a systematic analysis for the Global Burden of Disease Study 2021

Background: Disorders affecting the nervous system are diverse and include neurodevelopmental disorders, late-life neurodegeneration, and newly emergent conditions, such as cognitive impairment following COVID-19. Previous publications from the Global Burden of Disease, Injuries, and Risk Factor Study estimated the burden of 15 neurological conditions in 2015 and 2016, but these analyses did not include neurodevelopmental disorders, as defined by the International Classification of Diseases (ICD)-11, or a subset of cases of congenital, neonatal, and infectious conditions that cause neurological damage. Here, we estimate nervous system health loss caused by 37 unique conditions and their associated risk factors globally, regionally, and nationally from 1990 to 2021. Methods: We estimated mortality, prevalence, years lived with disability (YLDs), years of life lost (YLLs), and disability-adjusted life-years (DALYs), with corresponding 95% uncertainty intervals (UIs), by age and sex in 204 countries and territories, from 1990 to 2021. We included morbidity and deaths due to neurological conditions, for which health loss is directly due to damage to the CNS or peripheral nervous system. We also isolated neurological health loss from conditions for which nervous system morbidity is a consequence, but not the primary feature, including a subset of congenital conditions (ie, chromosomal anomalies and congenital birth defects), neonatal conditions (ie, jaundice, preterm birth, and sepsis), infectious diseases (ie, COVID-19, cystic echinococcosis, malaria, syphilis, and Zika virus disease), and diabetic neuropathy. By conducting a sequela-level analysis of the health outcomes for these conditions, only cases where nervous system damage occurred were included, and YLDs were recalculated to isolate the non-fatal burden directly attributable to nervous system health loss. A comorbidity correction was used to calculate total prevalence of all conditions that affect the nervous system combined. Findings: Globally, the 37 conditions affecting the nervous system were collectively ranked as the leading group cause of DALYs in 2021 (443 million, 95% UI 378–521), affecting 3·40 billion (3·20–3·62) individuals (43·1%, 40·5–45·9 of the global population); global DALY counts attributed to these conditions increased by 18·2% (8·7–26·7) between 1990 and 2021. Age-standardised rates of deaths per 100 000 people attributed to these conditions decreased from 1990 to 2021 by 33·6% (27·6–38·8), and age-standardised rates of DALYs attributed to these conditions decreased by 27·0% (21·5–32·4). Age-standardised prevalence was almost stable, with a change of 1·5% (0·7–2·4). The ten conditions with the highest age-standardised DALYs in 2021 were stroke, neonatal encephalopathy, migraine, Alzheimer's disease and other dementias, diabetic neuropathy, meningitis, epilepsy, neurological complications due to preterm birth, autism spectrum disorder, and nervous system cancer. Interpretation: As the leading cause of overall disease burden in the world, with increasing global DALY counts, effective prevention, treatment, and rehabilitation strategies for disorders affecting the nervous system are needed. Funding: Bill & Melinda Gates Foundation

Foreign Body (Bamboo Splinter of Broom Stick) in Soft Tissue

Patients with foreign bodies inside soft tissues are common in a surgeon's daily practice,. Radio-opaque foreign bodies can easily be located with radiography but radio-lucent foreign bodies cannot be located with X-ray, where Ultrasonography especially, high resolution ultrasonography can be used to locate it. Ultrasonography, being easily available, cost-effective and radiation-hazard free, can be done repeatedly for foreign bodies which move inside tissues. The presenting article describes a patient with a radio-lucent foreign body, deep inside muscle in his fore-arm and having one sharp end, was advancing inside tissues, was located with the help of Ultrasonography and was removed.   doi: 10.3329/taj.v20i1.3095 TAJ 2007; 20(1): 67-70</jats:p

Effect of Perioperative Administration of Tranexamic Acid on Postoperative Bleeding Following on Pump CABG

Background: One of the main causes of post-operative morbidity in cardiac surgical patient is excessive bleeding requiring transfusion of blood component after CPB. Re-exploration due to bleeding occurs in 2% to 7% of post bypass patient and 50% to 80% of these patients not having any identifiable surgical bleeding source. Tranexamic acid is competitive inhibitor of plasminogen activator and at higher concentration a non-competitive inhibitor of plasmin. It is 10 times more potent than Epsilone Aminocaproic Acid in preventing post-operative haemorrhage following CPB.&#x0D; Methods: This study was conducted in the Department of Cardiac Surgery, National Institute of Cardiovascular Diseases (NICVD), Dhaka, Bangladesh between January 2009 and December 2010. The Study population was divided into two groups. Group A comprised of 35 patients, who had received Tranexamic Acid 10 mg /kg after induction and then 1 mg/kg/hour till time of protamin infusion and Group B comprised of 35 patients who had received same amount of normal saline 0.9% NaCl as placebo.&#x0D; Results: The postoperative bleeding during both 1 to 4 hours and 4 to 24 hours was significantly lower in the Tranexamic Acid group as compared to the placebo group (p value &lt;0.001). There was no significant difference between groups in terms of platelet count and prothrombin time.&#x0D; Conclusion: From the study, we conclude that “Perioperative Administration of Tranexamic acid reduces post operative bleeding and also reduces the need for postoperative blood transfusion in CABG patents using Cardiopulmonary bypass”. Therefore it is recommended that routine prophylactic use of Tranexamic Acid should be carried out to decrease the postoperative hemorrhage and requirement blood transfusion.&#x0D; Cardiovasc. j. 2019; 12(1): 20-23</jats:p

Early Outcome of on Pump Beating Heart CABG Surger

Background: Current cardioplegic technique during conventional coronary artery bypass grafting (CABG) does not consistently avoid myocardial ischemic damage in high risk patients. Alternatively revascularization without CPB is not always technically feasible. The on-pump beating technique eliminates global myocardial ischemia and thus reduce the mortality and morbidity in high risk patients. This study evaluates the early surgical outcomes of on-pump beating-heart CABG in comparison to conventional CABG.&#x0D; Methods: In this prospective study 60 high risk patients with EURO-SCORE of 6 and above were prospectively allocated into two groups in non-randomized way. Among them 30 patients underwent on-pump beating-heart CABG and 30 patients underwent conventional CABG. The early surgical clinical outcomes were compared between the groups.&#x0D; Results: On-pump beating heart CABG significantly reduced the duration of operation time, cardiopulmonary bypass time, postoperative ventilation time and intensive care unit (ICU) stay. Total blood loss and transfusion requirement were less with reduced Peak Creatine-Kinase level in On-pump beating heart CABG. 30 day mortality was less in On-pump beating heart CABG group (6.7% versus 13.3%). No significant differences between the groups were found in morbidity regarding stroke, renal failure, mediastinitis and atrial arrhythmia.&#x0D; Conclusion: On-pump beating heart CABG can be performed safely in high risk patients. It is still associated with the detrimental effect of CPB but eliminates intra-operative global myocardial ischemia.&#x0D; Cardiovasc. j. 2019; 12(1): 13-19</jats:p

Spectrum of hypocalcaemia after thyroid surgery in Dhaka Medical College Hospital

Hypocalcaemia is not a uncommon complication after thyroid gland surgery. The extent of surgery and expertise are the vital factors to determine the spectrum of hypocalcaemia. This study was done to observe the spectrum of hypocalcaemia after different extent of thyroid gland surgery. A total of 70 consecutive patients were enrolled in the study by purposive sampling who received treatment for thyroid disorder in department of ENT and Head Neck Surgery, Dhaka Medical College Hospital, Dhaka, Bangladesh. They underwent different extent of thyroid surgery from January, 2017 to June, 2017. A prospective study was conducted for this 6 months period. A pre-structured, interview and observation based, peer reviewed data collection sheet was prepared. Data regarding sociodemographic, clinical, surgical and outcome profile were recorded. Data were compiled, edited and analyzed with SPSS version 23. Data were presented as mean and standard deviation, frequency percentage and median with range. The mean age of the respondents was 46.79±6.79 years (age range: 36-73 years.). Male to female ratio was 1:2.3. All the patients underwent total, near total, subtotal and completion thyroidectomy. 35(50%) and 28 (40%) patients underwent surgery due to papillary thyroid carcinoma and multinodular goiter respectively. Total of 30 patients developed hypocalcaemia. Among them, 22(73.33%) developed asymptomatic or mild hypocalcaemia which subsequently developed symptomatic hypocalcaemia (26.67%). Out of these 30 patients,15(50%) and 10 (33.33%) patients developed hypocalcaemia  intraoperative (20 minutes after surgery) and after 24 hours after surgery respectively. Serum calcium level significantly decreases after total thyroidectomy and most critical time is the first 24 hours of post thyroidectomy period.&#x0D; Bangladesh Med J. 2018 Jan; 47 (1): 1-5</jats:p