Gain peak-cavity mode alignment optimisation in buried tunnel junction mid-infrared GaSb vertical cavity surface emitting lasers using hydrostatic pressure

High-pressure techniques are used to investigate and optimise the design of GaInAsSb/AlGaAsSb vertical cavity surface emitting lasers (VCSELs) emitting at 2.4 µm. From measurements on edge emitting lasers it is found that non-radiative Auger recombination accounts for up to 85% of the threshold current at room temperature (RT) and is responsible for their strong temperature sensitivity. The effect of Auger recombination in VCSELs may be mitigated through judicious design of the gain peak–cavity mode (CM) alignment which may be investigated using high pressure. Results show that temperature insensitivity over the range −10 to +30°C may be obtained around RT if the gain peak is offset by approximately 10 meV higher in energy from the VCSEL CM

Band-structure and gain-cavity tuning of 2.4-µm GaSb buried tunnel junction VCSELs

Low-cost, continuous-wave GaSb-based vertical cavity surface emitting lasers (VCSELs) operating at ~ 2.4 mum up to 50degC have been demonstrated recently. In this work we have used high pressure techniques to investigate ways to improve their performance and extend their working temperature range. Since the band-gap and energy of the gain peak (Ep) increase with pressure at 0.126 meV/MPa at constant temperature, when applied to edge emitting lasers (EEL) we can use pressure to determine the radiative and non-radiative recombination processes occurring. In the VCSEL the pressure dependence of the threshold current, is much more complicated. At the higher temperature the decreasing Auger recombination initially dominates. Therefore we predict that either increasing the band gap or increasing the operating wavelength will allow an improved temperature performance of these GaSb-based VCSELs

Tehran environmental and neurodevelopmental disorders (TEND) cohort study: phase I, feasibility assessment

Purpose To advance knowledge about childhood neurodevelopmental disorders and study their environmental determinants, we conducted a study in Tehran, Iran to assess the feasibility of prospective birth cohort study. Methods We evaluated participation of pregnant women, feasibility of sampling biological material, and health care services availability in Tehran in four steps: (1) first trimester of pregnancy; (2) third trimester of pregnancy; (3) at delivery; and (4) two to three months after delivery. We collected related data through questionnaires, also various biological samples were obtained from mothers (blood, urine, milk and nails-hands and feet) and newborns (umbilical cord blood, meconium, and urine samples) from February 2016 to October 2017. Results overall 838 eligible pregnant women were approached. The participation rate was 206(25%) in our study and about 185(90%) of subjects were recruited in hospitals. Out of 206 participants in the first trimester, blood, urine, hand nail, and foot nail samples were collected from 206(100%),193(93%), 205(99%), and 205(99%), respectively. These values dropped to 65(54%), 83(69%), 84(70%), and 84(70%) for the remaining participants 120(58%) in the third trimester, respectively. Also, we gathered milk samples from 125(60%) of mothers at two to three months after delivery. Conclusion Our findings suggest that hospitals were better places for recruitment of subjects in a birth cohort in Tehran. We further concluded that birth cohort study recruitment can be improved by choosing appropriate gestational ages. Obtaining the newborn's urine, meconium, and umbilical cord blood were challenging procedures and require good collaboration between hospital staff and researchers

Tehran environmental and neurodevelopmental disorders (TEND) cohort study: Phase I, feasibility assessment

Purpose: To advance knowledge about childhood neurodevelopmental disorders and study their environmental determinants, we conducted a study in Tehran, Iran to assess the feasibility of prospective birth cohort study. Methods: We evaluated participation of pregnant women, feasibility of sampling biological material, and health care services availability in Tehran in four steps: (1) first trimester of pregnancy; (2) third trimester of pregnancy; (3) at delivery; and (4) two to three months after delivery. We collected related data through questionnaires, also various biological samples were obtained from mothers (blood, urine, milk and nails�hands and feet) and newborns (umbilical cord blood, meconium, and urine samples) from February 2016 to October 2017. Results: overall 838 eligible pregnant women were approached. The participation rate was 206(25) in our study and about 185(90) of subjects were recruited in hospitals. Out of 206 participants in the first trimester, blood, urine, hand nail, and foot nail samples were collected from 206(100),193(93), 205(99), and 205(99), respectively. These values dropped to 65(54), 83(69), 84(70), and 84(70) for the remaining participants 120(58) in the third trimester, respectively. Also, we gathered milk samples from 125(60) of mothers at two to three months after delivery. Conclusion: Our findings suggest that hospitals were better places for recruitment of subjects in a birth cohort in Tehran. We further concluded that birth cohort study recruitment can be improved by choosing appropriate gestational ages. Obtaining the newborn�s urine, meconium, and umbilical cord blood were challenging procedures and require good collaboration between hospital staff and researchers. © 2020, Springer Nature Switzerland AG

Islamic Veiling Meets Fashion – Struggles and Translations

The political controversies surrounding Muslim veiling today involve specific rhetorical elements deriving from long histories of colonialism, post-colonialism and neo-colonialism, and Muslim responses to these. A number of different languages – political, religious, patriarchal, feminist, sectarian, aesthetic – often get mixed up when Muslim veiling is talked about by diverse types of people, both Muslim and non-Muslim. Sartorial fashion is also spoken about in multiple registers: in terms of aesthetics, commercial considerations, social distinction and stratification, art, design and creativity. Both veiling and fashion have non-verbal languages, too. This chapter looks into the relationships between languages of veiling and languages of fashion. What happens when veiling becomes fashionable? What happens when fashionable forms of veiling appear, and an Islamic fashion industry emerges? There are three relevant types of language use here: those within Muslim communities, those outside Muslim communities, and those operating between Muslim and non-Muslim communities. These are shaped by power struggles of many sorts. As Foucault recognized, languages shape, hide and (re)produce power relations, such as in Orientalist forms of representation (Said), and in localized forms of silencing subaltern groups like lower-class women (Spivak). Such struggles become more complex when fashion languages and veiling languages meet. Fashionable veiling, or veiling fashion, can be a powerful tool for a Muslim woman, but it can also be rejected as oppressive or demeaning. These contradictory and intertwined elements of veiling languages and fashion languages are subjected here to cultural-historical sociological analysis