Exciton-polariton emission from organic semiconductor optical waveguides

We photo-excite slab polymer waveguides doped with J-aggregating dye molecules and measure the leaky emission from strongly coupled waveguide exciton polariton modes at room temperature. We show that the momentum of the waveguide exciton polaritons can be controlled by modifying the thickness of the excitonic waveguide. Non-resonantly pumped excitons in the slab excitonic waveguide decay into transverse electric and transverse magnetic strongly coupled exciton waveguide modes with radial symmetry. These leak to cones of light with radial and azimuthal polarizations

Preliminary report on two Triassic dicynodonts from Zambia.

Main articleThe purpose of this communication is to establish the presence of a species of Stahleckeriid, hitherto known only from India, in the Zambian Triassic N'tawere Formation and to establish the new specific name of the Kannemeyeria specimen also recorded from the same locality. The skulls and some post-cranial material of these two dicynodonts were collected by Mr. James Kitching from the Luangwa Valley, Zambia in 1961. The material comes from Locality 16, of the Lower Fossiliferous Horizon in the N'tawere Formation. One large skull has been assigned to genus and species Rechnisaurus cristarhynchus Roy Chowdhury, 1970. The other skull and the postcranial material has been named Kannemeyeria latirostris sp. nov. One other specimen has been described from this locality, Diademodon rhodesiensis (Brink 1963), which marks it as being of near Cynognathus-zone age.Non

Fat transforms ascorbic acid from inhibiting to promoting acid-catalysed N-nitrosation

<b>Background</b>: The major potential site of acid nitrosation is the proximal stomach, an anatomical site prone to a rising incidence of metaplasia and adenocarcinoma. Nitrite, a pre-carcinogen present in saliva, can be converted to nitrosating species and N-nitroso compounds by acidification at low gastric pH in the presence of thiocyanate. <b>Aims</b>: To assess the effect of lipid and ascorbic acid on the nitrosative chemistry under conditions simulating the human proximal stomach. <b>Methods</b>: The nitrosative chemistry was modelled in vitro by measuring the nitrosation of four secondary amines under conditions simulating the proximal stomach. The N-nitrosamines formed were measured by gas chromatography–ion-trap tandem mass spectrometry, while nitric oxide and oxygen levels were measured amperometrically. <b>Results</b>: In absence of lipid, nitrosative stress was inhibited by ascorbic acid through conversion of nitrosating species to nitric oxide. Addition of ascorbic acid reduced the amount of N-nitrosodimethylamine formed by fivefold, N-nitrosomorpholine by .1000-fold, and totally prevented the formation of N-nitrosodiethylamine and N-nitrosopiperidine. In contrast, when 10% lipid was present, ascorbic acid increased the amount of Nnitrosodimethylamine, N-nitrosodiethylamine and N-nitrosopiperidine formed by approximately 8-, 60- and 140-fold, respectively, compared with absence of ascorbic acid. <b>Conclusion</b>: The presence of lipid converts ascorbic acid from inhibiting to promoting acid nitrosation. This may be explained by nitric oxide, formed by ascorbic acid in the aqueous phase, being able to regenerate nitrosating species by reacting with oxygen in the lipid phase

Variations in caffeine and chlorogenic acid contents of coffees: what are we drinking?

The effect of roasting of coffee beans and the extraction of ground coffee with different volumes of hot pressurised water on the caffeine and the total caffeoylquinic acids (CQAs) content of the resultant beverages was investigated. While caffeine was stable higher roasting temperatures resulted in a loss of CQAs so that the caffeine/CQA ratio was a good marker of the degree of roasting. The caffeine and CQA content and volume was determined for 104 espresso coffees obtained from coffee shops in Scotland, Italy and Spain, limited numbers of cappuccino coffees from commercial outlets and several instant coffees. The caffeine content ranged from 48–317 mg per serving and CQAs from 6–188 mg. It is evident that the ingestion of 200 mg of caffeine per day can be readily and unwittingly exceeded by regular coffee drinkers. This is the upper limit of caffeine intake from all sources recommended by US and UK health agencies for pregnant women. In view of the variable volume of serving sizes, it is also clear that the term “one cup of coffee” is not a reproducible measurement for consumption, yet it is the prevailing unit used in epidemiology to assess coffee consumption and to link the potential effects of the beverage and its components on the outcome of diseases. More accurate measurement of the intake of coffee and its potentially bioactive components are required if epidemiological studies are to produce more reliable information

The experiences of midwives and women during intrapartum transfer from one-to-one midwife-led birth environments to obstetric-led units

Objective: To explore the transition from midwifery one-to-one support in labour within a midwife-led birth environment to an obstetricled unit from the perspectives of midwives and women. Design: Ethnographic study. Data was collected from eleven transfers to an obstetric-led unit. The transfer process was observed for four women. Semi-structured interviews were completed following the births with eleven women and eleven midwives. Nine maternity records were also analysed. Setting: An alongside midwife-led unit, freestanding midwife-led unit, women's homes in England. Findings: Territorial behaviour was the main theme experienced by midwives when transferring women to obstetric-led units. Territorial behaviour manifested itself as a feeling of 'us versus them' behaviours, 'feeling under scrutiny' and being aware of 'conflicting ideologies'. For women there were four themes that had an impact on their experiences of transfer obstetric-led units including: (1) their midwife continuing the care on the labour ward, (2) having time to adjust to their new situation, (3) all staff introducing themselves and (4) not being separated from their baby for long periods of time. Conclusion and implications for practice: Transfer from a midwife-led birth environment to an obstetric-led unit is a stressful situation for midwives and women. This paper highlights how territorial behaviours impacted negatively for midwives during transfer to an obstetric-led unit. More research is required to understand territorial behaviours within the maternity services and how more respectful compassionate working relationships can be created. Additionally, from the perspective of women this paper highlights four aspects of care that positively impacted on the experiences of women and even helped them to build resilience to cope with the change of location, situation, medical interventions and new carers when transferring to an obstetric-led unit

Fetal liver blood flow distribution: role in human developmental strategy to prioritize fat deposition versus brain development

Among primates, human neonates have the largest brains but also the highest proportion of body fat. If placental nutrient supply is limited, the fetus faces a dilemma: should resources be allocated to brain growth, or to fat deposition for use as a potential postnatal energy reserve? We hypothesised that resolving this dilemma operates at the level of umbilical blood distribution entering the fetal liver. In 381 uncomplicated pregnancies in third trimester, we measured blood flow perfusing the fetal liver, or bypassing it via the ductus venosus to supply the brain and heart using ultrasound techniques. Across the range of fetal growth and independent of the mother's adiposity and parity, greater liver blood flow was associated with greater offspring fat mass measured by dual-energy X-ray absorptiometry, both in the infant at birth (r = 0.43, P<0.001) and at age 4 years (r = 0.16, P = 0.02). In contrast, smaller placentas less able to meet fetal demand for essential nutrients were associated with a brain-sparing flow pattern (r = 0.17, p = 0.02). This flow pattern was also associated with a higher degree of shunting through ductus venosus (P = 0.04). We propose that humans evolved a developmental strategy to prioritize nutrient allocation for prenatal fat deposition when the supply of conditionally essential nutrients requiring hepatic inter-conversion is limited, switching resource allocation to favour the brain if the supply of essential nutrients is limited. Facilitated placental transfer mechanisms for glucose and other nutrients evolved in environments less affluent than those now prevalent in developed populations, and we propose that in circumstances of maternal adiposity and nutrient excess these mechanisms now also lead to prenatal fat deposition. Prenatal developmental influences play important roles in the human propensity to deposit fa