A variety of lepton number violating processes related to Majorana neutrino masses

A Majorana type of the neutrino mass matrix induces a class of lepton number violating processes. Cross sections of these reactions are given in terms of the neutrino mass matrix element, and a semi-realistic event rate is estimated. These processes provide mass and mixing parameters not directly accessible by the neutrino oscillation experiments. If these processes are discovered with a larger rate than given here, it would imply a new physics of the lepton number violation not directly related to the Majorana neutrino mass, such as R-parity violating operators in SUSY models.Comment: 15 pages, 1 figur

Boron-oxygen defect imaging in p-type Czochralski silicon

In this work, we demonstrate an accurate method for determining the effective boron-oxygen (BO) related defect density on Czochralski-grown silicon wafers using photoluminescence imaging. Furthermore, by combining a recently developed dopant density imaging technique and microscopic Fourier transform infrared spectroscopy measurements of the local interstitial oxygen concentration [Oi ], the BO-related defect density, [Oi ], and the boron dopant density from the same wafer were determined, all with a spatial resolution of 160 μm. The results clearly confirm the established dependencies of the BO-related defect density on [Oi ] and the boron dopant density and demonstrate a powerful technique for studying this important defect.This work was supported by the Australian Research Council (ARC) Future Fellowships program and the Australian Renewable Energy Agency (ARENA) fellowships program

Kinetics and moving species during Co2Si formation by rapid thermal annealing

We have investigated the growth kinetics and identified the moving species during Co2Si formation by rapid thermal annealing (RTA). For the kinetics study, samples which consisted of a thin Co film on an evaporated Si substrate were used. To study which species moves, samples imbedded with two very thin Ta markers were employed. Upon RTA, only one silicide phase, Co2Si, was observed to grow before all Co was consumed. The square root of time dependence and the activation energy of about 2.1±0.2 eV were observed during the Co2Si formation up to 680 °C. The marker study indicated that Co is the dominant mobile species during Co2Si formation by RTA. We conclude that Co2Si grows by the same mechanisms during RTA and conventional thermal annealing

Development of an NFT system of soilless culture for the tropics

The development of a soilless crop culture system based upon the Nutrient Film Technique (NFT) was studied. The conventional polythene gullies used for the NFT in temperate regions were found not suitable for the hot tropical climate. An insulated NFT shallow trough design was effective in controlling heat build up In the root zone. Muskmelon, vegetables and ornamental plants were successfully grown with the NFT trough system designed. This system is cheap, economical, labor saving and versatile

Silicon resistor to measure temperature during rapid thermal annealing

A resistor composed of a piece of Si wafer and two thin silver wires attached to it, can reliably sense the temperature during rapid thermal annealing (RTA). As constant electric current passes through the Si piece, the resistivity change of Si with temperature produces a voltage signal that can be readily calibrated and converted to an actual temperature of the samples. An accuracy better than ±10 °C is achieved between 300° and 600 °C

Pollen Studies on Vida laba L. I, Germination Medium and Incubation Duration and Temperature

The optimum culture conditions for V. faba pollen in vitro were determined using factorial combinations of agar and sucrose concentrations with various incubation durations and temperatures. Maximum pollen germination and the growth was obtained using a culture medium c0nsisting of 2% agar and 25% sucrose and incubating for 2 hours at 25°C. The bursting of pollen grains and tubes were minimum under these conditio

AGE DIFFERENCES AND MACROECONOMIC EFFECTS ON FOOD STAMP PROGRAM PARTICIPATION

Low income populations are more severely affected by economic downturns than their high income counterparts because they are at high risk of unemployment and face reduced earnings in recessions. The use of food stamp benefits and other types of welfare are one mechanism that families can use to buffer the economic shock brought about by income losses due to unemployment during a recession. As a result, during unfavorable economic conditions, low income households disproportionately rely on public assistance including food stamps. What is less understood are the differential effects of macroeconomic conditions on the participation propensities of different population subgroups. Of particular importance are differential effects by age. Depending on their age, poor workers are likely to experience different patterns of unemployment so that their welfare participation patterns also differ. For example, once older workers lose their jobs, their probability of re-employment is lower than that of their younger counterparts. The reduced expectations of re-employment coupled with fewer opportunities to invest in re-training are discouraging to older unemployed persons, often implying that job losses for older workers are permanent, and eventually lead to long term reliance on welfare programs. In contrast, younger poor workers have comparatively higher chances of re-employment and exit from welfare. Whether the age differences in welfare participation will remain unchanged during economic recessions as well is still unanswered. Understanding variations in FSP participation propensities across age groups and their dependency on macroeconomic conditions is essential to predict future demand for food stamp benefits and, by extension, other welfare programs. The continuing growth in FSP demand may point to unexpectedly large fiscal burdens for future taxpayers. Moreover, understanding differential effects of macroeconomic conditions on participation propensities for different groups will allow policy makers to better identify and eventually reach genuine needy families. Therefore, this study aims to investigate FSP participation patterns with a special emphasis on the differential impact of macroeconomic factors across several demographic groups with a particular focus on age cohort effects. Specifically, transitions into and out of FSP will be explicitly addressed using longitudinal data from the Survey of Income and Program Participation (SIPP) 2004 panel. To measure the impact of economic conditions, we match SIPP data with economic measures such as the unemployment rate and wages at the state level available from the Bureau of Labor Statistics. Using the data, monthly movements on and off of FSP of individuals is followed and categorized into entry sample and continuation sample. A household not participating in FSP in one month, and thus being part of the entry sample, can choose between entering or not entering FSP in the subsequent month. Similarly, a household enrolled in one month (and thus part of the continuation sample) can choose between either continuing to stay on FSP or exiting FSP in the next month. This gives rise to two types of transition models. The first model, referred to as the entry model, tackles the decision between entry versus non-entry into FSP, conditional on non-participation in the previous months. The second model, referred to as continuation model, addresses the decision between exiting from versus continuing FSP, conditional upon participation in the preceding month. Two transition models are estimated using probit technique while controlling for individual specific effects. This study finds several important results. First, there are significant age differences in entry into and exit from the FSP. The propensity of entry into the FSP among younger people is higher than among older people while young cohorts are more prone to exiting FSP than the oldest cohort of retired or retirement-bound people. The implication for the elderly is that once receiving FSP benefits, they are very likely to continue the FSP. Their observed low FSP participation rates can thus primarily be attributed to FSP entry barriers. Second, rising unemployment boosts FSP entry propensities and lengthens FSP spells. Changes in wage levels, however, affect neither entry nor exit propensities. Third, the effect of unemployment on FSP continuation propensities varies by age. The youngest cohort responds to increasing unemployment by drastically prolonging their FSP spells whereas the older extend their FSP spells more gradually. For the oldest cohort, FSP exit probabilities are even found to rise in association with rising unemployment, a phenomenon that can be explained by retirement and special transfer programs for the elderly.Food Stamp Program, Age, Macroeconomy, Transition, Agricultural and Food Policy, Food Consumption/Nutrition/Food Safety, I38, J64,

Study of large adaptive arrays for space technology applications

The research in large adaptive antenna arrays for space technology applications is reported. Specifically two tasks were considered. The first was a system design study for accurate determination of the positions and the frequencies of sources radiating from the earth's surface that could be used for the rapid location of people or vehicles in distress. This system design study led to a nonrigid array about 8 km in size with means for locating the array element positions, receiving signals from the earth and determining the source locations and frequencies of the transmitting sources. It is concluded that this system design is feasible, and satisfies the desired objectives. The second task was an experiment to determine the largest earthbound array which could simulate a spaceborne experiment. It was determined that an 800 ft array would perform indistinguishably in both locations and it is estimated that one several times larger also would serve satisfactorily. In addition the power density spectrum of the phase difference fluctuations across a large array was measured. It was found that the spectrum falls off approximately as f to the minus 5/2 power