ALBERT

Notes: We report measurements of the dc and microwave properties of epitaxial thin films of Tl2CaBa2Cu2O8 on LaAlO3. ac magnetic susceptibility measurements yield critical temperatures at the transition midpoint Tc∼100 K and 10–90% transition widths of ∼1.0 K. We observed a critical current density of 1.06×106 A/cm2 at 77 K measured by dc transport. We measured a low-power surface resistance of Rs=0.2 mΩ at 9.55 GHz and 77 K. This is ∼50 times lower than oxygen-free high-conductivity (OFHC) Cu at the same frequency and temperature. At 90 K, RS rises to 0.4 mΩ, and at 95 K, RS=0.7 mΩ. We measured the microwave power dependence of RS at 77, 90, and 95 K. At high microwave field ((approximately-greater-than)30 G, 77 K) Rs=0.8 mΩ, more than ten times lower than OFHC Cu.

Notes: We have fabricated and tested a 1 ns microstrip delay line using thin films of Tl2Ba2CaCu2O8. We determined the loss in the delay line by weakly coupling at the input and output and measuring the width of the fundamental resonance at 461 MHz. At 15 K, the loss was lower than that calculated for an equivalent cryogenic copper line by a factor of 300. Resonance peaks were observable up to 102.7 K. At 77 K and 3.29 GHz, the observed loss was lower than that calculated for an equivalent Cu line by a factor of 10. Power limiting due to film defects occurred at an effective power level in the line of −43 dBm at 15 K.

Notes: Food insecurity or lack of access to adequate and nutritious food is a major determinant of under-nutrition. Expenditure patterns accompanied by unemployment, low level of education, inflation and high food prices have a direct negative impact on food availability within households (Moller, 1997). Ghany and Schwenk (1993) found that as household income increases, the proportion of expenditures on food decreases, the proportion of expenditures on clothing, rent, fuel, and light stayed the same and that of sundries increased.The aim of this study was to investigate household expenditure patterns on food and non-food items in Khayelitsha. A total of 20 households (10 from the formal and 10 from the informal settlements) were randomly selected from those willing to participate in the study. A questionnaire with open ended and closed questions was used to collect data. The questionnaire comprised four sections namely: biographical information, socio-economic information which used wealth quintiles to assess households’ social economic status, total expenditure information and a food/hunger scale was used to assess households’ food availability.The findings revealed that households from informal settlements spent more money (62.2%) as a proportion of their income on food compared to households from the formal settlement (39%). There was higher unemployment rate (100%) at the informal settlement compared to the formal settlement (40%). Wealth quintiles scales did not reflect the social status of the households as equipment and assets owned by households were only used as fallback position during times of economic hardships.Households used different purchasing strategies; food and non-food items were mainly purchased from outside the township (60%). Forty percent of the households bought their items from local shops and spazas because they allowed them to buy items whenever little money was available or to take items on credit. All the respondents preferred to buy bread and small items from spazas and local shops. Prices of items in the spazas and local shops were higher compared to prices of items in bigger shops outside the townships.The food/hunger scale and wealth quintiles showed that informal settlement households were more food insecure (as they were all unemployed and about 50% of the households ran out of food always) and had fewer assets compared to the formal settlement households.The implications of these findings underscore the need to improve socio-economic conditions of low resource households through empowerment programs. These programs can be in the form of training in management/decision making, work related skills/literacy (to help them access formal employment), business management/income generation skills (to help them to be self-employed), budgeting, and food gardening. This approach can help to increase the resource base and alleviate food insecurity in low resource households.

Notes: Millimeter mixers have been fabricated from epitaxial films of Tl2CaBa2Cu2O8, using a bowtie antenna structure integrated with grain-boundary weak links that were deliberately formed during film growth. The bowtie antenna was utilized for broadband millimeter wave coupling of the radiation into the weak links. Heterodyne mixing of signals at both V band (55 GHz) and W band (94 GHz) frequencies, and subharmonic mixing at V has been observed at liquid nitrogen temperature for zero and finite bias voltage conditions. The dependence of the IF output on temperature, bias voltage, and millimeter wave signal power has been studied. Efficient mixing with bias voltage exhibited strong signals right up to Tc (101 K).