Spatially resolving valley quantum interference of a donor in silicon

Electron and nuclear spins of donor ensembles in isotopically pure silicon experience a vacuum-like environment, giving them extraordinary coherence. However, in contrast to a real vacuum, electrons in silicon occupy quantum superpositions of valleys in momentum space. Addressable single-qubit and two-qubit operations in silicon require that qubits are placed near interfaces, modifying the valley degrees of freedom associated with these quantum superpositions and strongly influencing qubit relaxation and exchange processes. Yet to date, spectroscopic measurements have only probed wavefunctions indirectly, preventing direct experimental access to valley population, donor position and environment. Here we directly probe the probability density of single quantum states of individual subsurface donors, in real space and reciprocal space, using scanning tunnelling spectroscopy. We directly observe quantum mechanical valley interference patterns associated with linear superpositions of valleys in the donor ground state. The valley population is found to be within 5% of a bulk donor when 2.85 ± 0.45 nm from the interface, indicating that valley-perturbation-induced enhancement of spin relaxation will be negligible for depths greater than 3 nm. The observed valley interference will render two-qubit exchange gates sensitive to atomic-scale variations in positions of subsurface donors. Moreover, these results will also be of interest for emerging schemes proposing to encode information directly in valley polarization.

Pregnancy with myasthenia gravis

Myasthenia gravis (MG) is an autoimmune disorder of the neuromuscular transmission, caused by auto antibodies against the nicotinic acetylcholine receptor. These antibodies of the IgG isotype are detected in 80-90% of generalized MG and in 50-70% of ocular MG. Seronegative MG is caused by humoral factors. Prevalence of MG lies between 1 in 10.000 and 1 in 50.000, with 2/3 of affected individuals being female. In the case of maternal myasthenia gravis, both the mother and the child may develop myasthenia symptoms with varying degrees of weakness and progressive fatigability of the skeletal muscles. Data for the case report were generated by reviewing labour, delivery, and postpartal records. We present a 26 years old lady who suffered from a generalized form of myasthenia gravis since the age of 15. She got herself admitted to a neurologic clinic for a myasthenic crisis when she was two and half months pregnant. The patient was treated with anticholinesterase medication, corticosteroids and intravenous immunoglobulin. Clinically, the patient's condition improved significantly during pregnancy. Delivery and the post delivery period were also normal for the patient. Myasthenia gravis especially when associated with pregnancy is a high-risk disease. As this disease predominantly occurs in women of reproductive age, it is important to be aware of this condition in obstetrics and its interdisciplinary diagnostic and therapeutic management is required.

Early surgery for epiretinal membrane preserves more vision for patients

PURPOSE

To establish whether early vitrectomy for epiretinal membrane (ERM) is preferable to delayed surgery.

METHODS

We carried out a retrospective study of 120 eyes from 120 patients with pre-operative visual acuity (VA) of 6/60 or better. Pre-operative logMAR score was considered to act as an appropriate proxy measure for time of surgical procedure, with scores of 0.3 or less considered to represent early surgery, scores of 0.4 or 0.5 considered to represent medium surgery, and scores of 0.6 or more considered to represent late surgery for ERM. Patients were either pseudophakic at the time of vitrectomy or underwent combined phaco-vitrectomy for symptomatic ERM.

RESULTS

Evaluation of parameter coefficients indicated that controlling for other factors, a delay of the surgical procedure from a state of early to medium corresponded to an increase (ie, disbenefit) of 0.074 units in post-operative logMAR score (95% confidence interval -0.001-0.15). A delay of the surgical procedure from a state of early to late corresponded to an increase (ie, disbenefit) of 0.21 units in post-operative logMAR score (95% confidence interval 0.13-0.29). Mean post-operative VA for early surgery was 0.16, out of which 36.2% of patients had a LogMAR score of 0.1 or better. This is in comparison to 17.2% in late ERM (those with a pre-operative logMAR score of 0.6 or more).

CONCLUSION

We conclude that early surgery is associated with a lower (ie, better) post-operative logMAR score. Vitrectomy for early symptomatic ERM, in carefully selected patients, is beneficial in preserving excellent vision and allows quicker visual rehabilitation.

Risk factors of acute coronary syndrome among Bangladeshi people

Two hundred consecutive patients of acute coronary syndrome aged 30-80 years (inclusive) admitted to the coronary care unit of National institute of Cardiovascular Diseases, Dhaka, were prospectively recruited as cases. Two hundred controls were prospectively selected either from individuals attending in the Shaheed Suhrawardy Medical College Hospital, admitted for elective surgery or in medicine ward for conditions that were unlikely to confound a comparative analysis. The Cases had significantly lower yearly incomes than controls, and significantly higher number of cases is occupied as sedentary worker. Smoking was an important risk factor. About 70% of cases and 45% of controls smoked previously cigarettes. Consumption of non smoke tobacco is another risk factor. The high risk of IHD in developing countries attributed to low consumption of fruit and vegetables, and in our study regular consumption of fruits (taking fruit at least 4 days a week) shows 20.5% cases and 33% of controls (OR 0.524, 95%CI 0.333-0.823) and p value was 0.005. Around 23.5% of the cases were diabetic compared with 4.5% of controls. We found 5% cases and 1.5% controls having known dyslipidemia. Although the body-mass index of cases was 24.68±3.06 Kg/M² and controls 20.54±4.37 Kg/M². The WHR was also significantly greater in cases 0.98±0.05M vs. controls 0.93±0.102M (p<0.001). About 31% of cases and 2% of controls had past history of myocardial infarction. The most predictive independent variables were previous smoking (p<0.001), WHR (p<0.001), history of hypertension (p<0.001), and income (p<0.001). Smoking and WHR were associated with the highest risks. The variables revealed to be significantly associated with acute coronary syndrome by bivariate analyses were all entered into the model directly. Eleven variables entered into the model. Of them Age, occupation, family income (yearly), fruit consumption, known hypertension, known DM, known dyslipidemia, previous MI, previous smoking, BMI and Waist and hip ratio were found to be the independent predictors of acute coronary syndrome. The study found that smoking tobacco, diabetes mellitus, hypertension, visceral obesity and less fruit intake are the important factors of acute coronary syndrome in Bangladesh.

Research advisory board members' contributions and expectations in the USA

This study focuses on the Implementation Community Collaborative Board (I-CCB) to identify members' anticipated contributions to and returns from the I-CCB; examine whether or not members achieved these contributions and returns over time; and explore barriers and facilitators that influenced accomplishments. Longitudinal study with repeated semi-structured in-depth interviews; baseline captured anticipated contributions and returns; 6- and 18-month follow-ups short- and longer-term achievements. We used content analysis to code/reduce text into variables, describe, count and compare categories. Participants anticipated involvement in I-CCB dynamics/governance and in research tasks/procedures. Anticipated returns included social support. Participants exerting influence on I-CCB's research agenda stayed the same over time. Participants conducting research doubled between follow-ups; those writing grant proposals increased by 50%. Participants receiving emotional support remained the same. Challenges: meetings steered by researchers; lack of time; use of jargon. Facilitators: outreaching to community; being affected by HIV; having overlapping identities/roles as researcher, service consumer and/or practitioner. Research partners can maximize facilitators, redress barriers and improve advisory board members' retention. Findings may help optimize the functioning of advisory boards worldwide.

Effects of third trimester counseling on pregnancy weight gain, birthweight, and breastfeeding among urban poor women in Bangladesh

BACKGROUND

Maternal malnutrition and poor gestational weight gain are the most important causes of low birth weight and high rates of newborn mortality.

OBJECTIVE

To assess the effects of nutrition counseling in the third trimester of pregnancy on maternal weight gain, birth weight of newborn, and breastfeeding practices.

METHODS

This was a longitudinal experimental study with nutrition intervention for a period of 3 months. One hundred fifteen women (57 in the intervention group and 58 in the comparison group) who were visiting the Maternal and Child Health Training Institute at 6 months of pregnancy were randomly selected. The intervention group was given nutrition education twice in the first month and once a month for the next 2 months before delivery; the comparison group received routine hospital advice on food intake, immunization, personal hygiene, and breastfeeding. The women were weighed monthly up to delivery, the newborn infants' birth weights were measured within 24 hours after delivery, and breastfeeding practices were observed 1 month after delivery.

RESULTS

Women in the intervention group gained 1.73 kg more weight during the third trimester than women in the comparison group (5.61 vs. 3.88 kg, p < 0.001). The mean birthweight of babies of women in the intervention group was 0.44 kg greater than that of babies of women in the comparison group (2.86 vs. 2.42 kg, p < 0.001). In the intervention group, 10.5% of babies were born with low birthweight, compared with 48.3% of the babies of women in the comparison group (p < 0.001). In the intervention group, 75.4% of mothers initiated breastfeeding within 1 hour after birth, compared with 34.5% of mothers in the comparison group (p < 0.001).

CONCLUSIONS

Nutrition education only during the third trimester improved weight gain during pregnancy, reduced 78% of low birth weight, and improved breastfeeding practices.

Maternal serum zinc level and its relation with neonatal birth weight

The present study was conducted in the Department of Obstetrics & Gynaecology, Mymensingh Medical College Hospital, Mymensingh and Molecular Microbiology & Central Laboratory of Bangladesh Institute of Nuclear Agriculture (BINA) from 15th November 2007 to 31st May 2009 to find out the relation between maternal serum zinc level with neonatal birth weight. Hundred pregnant women who were advised to take 61.8 mg zinc daily throughout pregnancy were assigned to study group while the pregnant woman did not take zinc orally were allocated into control group. Serum zinc levels were measured between 37-42 weeks gestation and birth weight were measured just after delivery. Data were processed and analyzed using SPSS version 11.5. The test used to analyze the data was descriptive statistics, Chi-square probability test, Pearson correlation, unpaired t-test and odds ratio. A probability value of <0.05 was considered significant. Majority (97%) of the cases who received zinc during their antenatal period had normal serum zinc (≥ 700μg/L) level compared to only 22% of the control group woman who did not receive zinc. Normal birth weight of babies in pregnant woman who received zinc is 5.7 times higher than the pregnant woman who did not receive zinc. As the present study was a cross-sectional one, further study with large sample size and prospective design is recommended.

Ab-initio adsorption study of chitosan on functionalized graphene: critical role of van der Waals interactions

We investigate the adsorption process of an organic biomolecule (chitosan) on epoxy-functionalized graphene using ab-initio density functional methods incorporating van-der-waals (vdW) interactions. The role of London dispersion force on the cohesive energy and conformal preference of the molecule is quantitatively elucidated. Functionalizing graphene with epoxy leads to weak hydrogen-bond interactions with chitosan. Binding energy values increase by over an order of magnitude after including vdW corrections, implying that dispersive interactions dominate the physisorption process. Conformal study show binding upto 30 kcal/mol when the molecule is oriented with the hydroxyl group approaching the functionalized graphene. Our study advances the promise of functionalized graphene for a variety of applications.

Prevalence of diabetes among hypothyroid subjects

Thyroid dysfunction affects a significant portion of the general population. Most studies have found a higher prevalence of hypothyroidism in women, increasing with age. Prevalence of hyperthyroidism has been found to range 0.5-3.0%. Type 2 diabetes is a major public health problem affecting approximately 4.8 percent of the Bangladeshi population. The study was designed to see the prevalence of type 2 diabetes in hypothyroid patients of any etiology. Four hundred forty two consecutive cases of diagnosed hypothyroidism were recruited in the study. All diagnosed hypothyroid subjects (sub-clinical or overt) reported in one year not known to be diabetic previously, underwent standard OGTT (FPG and 2-hour post 75 gram glucose) before initiation of thyroid hormone replacement. Newly detected diabetes among the subjects diagnosed as hypothyroidism is significantly higher 4.8 vs. 7.01% (p<0.01) and the prevalence of pre-diabetic state Impaired Glucose Tolerance (IGT) is also higher (11% vs. 12.6%) among hypothyroid subjects. Pure IFG (FPG ≥6.1 mmol/l but <7.0 mmol/l, and 2-PG <7.8 mmol/l) was found in 5.2% according to WHO criteria and the prevalence is higher (6.8%) with ADA criteria (considering normal FBG <5.6mmol/l). Diabetes was found in 7.01% among hypothyroid subjects which is higher than the existing known prevalence (4.8%). IGT was also found higher among hypothyroid subjects than population prevalence (8.6%). Further larger sample study is essential to establish the findings.