Variation of Electrostatic Coupling and Investigation of Current Percolation Paths in Nanocrystalline Silicon Cross Transistors

Nanocrystalline silicon thin films are promising materials for the development of advanced Large Scale Integration compatible quantum-dot and single-electron charging devices. The films consist of nanometer-scale grains of crystalline silicon, separated by amorphous silicon or silicon dioxide grain boundaries up to a few nanometer thick. These films have been used to fabricate single-electron transistor and memory devices, where the grains form single-electron charging islands isolated by tunnel barriers formed by the grain boundaries. The grain boundary tunnel barrier isolating the grains is also of great importance, as this determines the extent of the electrostatic and tunnel coupling between different grains. These effects can lead to the nanocrystalline silicon thin film behaving as a system of coupled quantum dots.& more..

Menstrual irregularities, hormonal imbalances and obesity in teenage and adolescent girls in Hyderabad, Sindh, Pakistan

Background: Obesity in young girls adversely affects reproductive health later in life and it is a serious public health issue. The objective was to study the association of obesity with menstrual irregularities and hormonal imbalance in teenage and adolescent girls. Method: Participants comprised a convenience sample of 12-19 years old girls (N=83). The study was conducted in outpatient clinics at a university hospital. Data were collected through medical history by interview, physical examination and blood tests. Data were analysed using frequencies, descriptive statistics, Chi Squared tests of Independence and Binary Logistic Regression. Results: The median age was 16 years (mean 15.9, SD 2.2) and the median BMI was 31.14 (mean 32.04, SD 4.51). Most of the girls were obese (95.2%) and some had a family history of obesity (33.7%), diabetes (28.9%) and cardiovascular disease (20.5 %). Clinical presentations included secondary amenorrhea (34.9%), heavy and irregular periods (22.9%) and oligomenorrhea (16.9%). Girls with a polycystic ovary (54.2%, n=45) had a reversed follicle stimulating hormone (FSH) / luteinizing hormone (LH) ratio (OR 11.33, 95% CI 2.98, 43.04, p < 0.001), an upper limit or raised fasting insulin (OR 7.20, 95% CI 2.33, 22.22, p < 0.001), a raised testosterone (OR=5.16, 95% CI 1.56, 17.11, p = 0.007 and a disturbed lipid profile (OR 5.67, 95% CI 1.72, 18.73, p = 0.004). Obesity was not statistically significantly associated with either polycystic ovary syndrome (PCOS) or any of the measured hormone levels. Conclusion: Adolescent girls presenting with obesity, menstrual irregularities and hormonal imbalance may suggest manifestation of PCOS, which needs early investigation and proper management

Chloramphenicol therapy of typhoid fever

In a prospective study we compared two different dosage regimens of IV chloramphenicol succinate (100 mg/kg/day and 75 mg/kg/day) in children with culture proven typhoid. Trough and peak blood samples, obtained at 48 hrs, were analysed for free chloramphenicol by high pressure liquid chromatography (HPLC). Although the mean trough (8.8 +/- 7.7 versus 5.4 +/- 2.6 mcg/ml) and peak (19.9 +/- 12.2 versus 15.4 +/- 6.1 mcg/ml) chloramphenicol concentrations were comparable in both groups, a significantly wider range was found in the group receiving 100 mg/kg/day. Potentially toxic levels (greater than 30 mcg/ml) developed in two patients with liver dysfunction. Chloramphenicol in a dosage of 75 mg/kg/day is adequate and safe for the treatment of paediatric typhoid

A philosophical context for methods to estimate origin-destination trip matrices using link counts.

This paper creates a philosophical structure for classifying methods which estimate origin-destination matrices using link counts. It is claimed that the motivation for doing so is to help real-life transport planners use matrix estimation methods effectively, especially in terms of trading-off observational data with prior subjective input (typically referred to as 'professional judgement'). The paper lists a number of applications that require such methods, differentiating between relatively simple and highly complex applications. It is argued that a sound philosophical perspective is particularly important for estimating trip matrices in the latter type of application. As a result of this argument, a classification structure is built up through using concepts of realism, subjectivity, empiricism and rationalism. Emphasis is put on the fact that, in typical transport planning applications, none of these concepts is useful in its extreme form. The structure is then used to make a review of methods for estimating trip matrices using link counts, covering material published over the past 30 years. The paper concludes by making recommendations, both philosophical and methodological, concerning both practical applications and further research

Comments on "Limits on Dark Matter Using Ancient Mica"

To appear in Phys. Rev. Lett. together with the author's Reply.Comment: Compressed PostScript (filename.ps.Z), 3 pages, no figure