Examining monaural and binaural measures of phase-locking as a function of age

Understanding speech in the presence of background noise is a common complaint of middle-aged and older listeners with clinically normal audiograms. There is great interest in understanding how age-related changes in auditory physiology make it harder for older adults to understand speech in difficult listening situations, compared to young listeners. It was recently reported that middle-aged and older normal-hearing listeners showed frequency-dependent, age-related declines in the behavioral and physiological detection of interaural phase differences (Grose & Mamo, 2010; Ross et al, 2007). There is also evidence of an age-related, frequency-dependent decline in the frequency-following response (FFR) (Clinard et al., 2010), an auditory evoked potential dependent on phase-locked neural activity (Worden & Marsh, 1968). Age-related declines in binaural processing may be related to age-related declines in phase locking. This study used the frequency-following response (FFR) to examine monaural and binaural phase locking in subjects of two groups; younger and middle-aged. Responses were obtained from 300 ms toneburst stimuli at four frequencies (500, 750, 1000, and 1125 Hz) at an intensity of 80 dB SPL. FFRs were analyzed for response amplitude, binaural amplitude differences, and stimulus-to-response cross-correlations. Results showed FFR amplitude decreased as frequency increases and, at 500 Hz, the summed left and right monaural FFR amplitudes were smaller than the binaural FFR amplitude, which is in contrast to previous literature (Clinard, 2010; Fowler, 2004; Krishnan & McDaniel, 1998). Results further indicated that the stimulus-to-response correlation coefficient is greatest for 500 Hz and declines as frequency increases. There was no significant difference between the age groups but perhaps a broader age range including older adults would show the hypothesized amplitude differences between groups. Further, results may be different than expected due to minimal difference between summed monaural and binaural processing at 750, 1000, and 1125 Hz. When looking at the data there is a larger difference between groups at 1125 Hz and, while it is not significantly different, it may be that a broader frequency range (e.g., 1250 Hz or above) and age range (e.g. 0 to 100), may be more effective at revealing a group x frequency interaction

Quantifying How High Tunnels Create a Microclimate For Improved Crop Growth

Farmers in the Great Basin are investing in inexpensive low-tech greenhouses, known as high tunnels (HTs) or hoop houses. This study evaluated the microclimate inside HTs, how farmers were using HTs to grow crops and how the microclimate inside HTs led to improved crop growth. The HT microclimate varied by season, with more growing degree days inside the HT than outside in the spring, fall and winter. The way farmers managed HTs using manual ventilation, shade cloth and fans was the strongest determinant of how the climate inside the HT was different from outside. HTs increased vapor pressure, leading to potentially less need for irrigation water. By creating microclimates suitable to crop growth, farmers were able to extend the growing season, grow a wider variety of crops and improve yields. HTs improved the economic viability of farms for farmers who had been using them for several years. HTs in the high desert are only increasing in popularity and farmers are continuing to use and recommend them to other farmers

Sorgo: uma alternativa para cultivo de verão em Mato Grosso do Sul.

bitstream/item/65592/1/Cot24-2000.pdfDocumento online

Avaliação da cultura do girassol (Helianthus annuus L.) em duas épocas de semeadura, em Mato Grosso do Sul.

bitstream/item/39706/1/COT-01-1999.pd

Desempenho de genótipos de arroz irrigado em Mato Grosso do Sul.

bitstream/item/65825/1/COT87-2004.pd

O algodoeiro em rotação com a soja no sistema plantio direto.

bitstream/item/40080/1/PA-1-1999.pd

Produtividade do algodoeiro em rotação com soja no sistema plantio direto.

bitstream/item/65691/1/Cot-34-2001.pd

Development of the electroweak phase transition and baryogenesis

We investigate the evolution of the electroweak phase transition, using a one-Higgs effective potential that can be regarded as an approximation for the Minimal Supersymmetric Standard Model. The phase transition occurs in a small interval around a temperature T_t below the critical one. We calculate this temperature as a function of the parameters of the potential and of a damping coefficient related to the viscosity of the plasma. The parameters that are relevant for baryogenesis, such as the velocity and thickness of the walls of bubbles and the value of the Higgs field inside them, change significantly in the range of temperatures where the first-order phase transition can occur. However, we find that in the likely interval for T_t there is no significant variation of these parameters. Furthermore, the temperature T_t is in general not far below the temperature at which bubbles begin to nucleate.Comment: 26 pages, 7 figures; typos corrected, reference adde

Maize yield and rainfall on different spatial and temporal scales in Southern Brazil

This study aimed to establish relationships between maize yield and rainfall on different temporal and spatial scales, in order to provide a basis for crop monitoring and modelling. A 16-year series of maize yield and daily rainfall from 11 municipalities and micro-regions of Rio Grande do Sul State was used. Correlation and regression analyses were used to determine associations between crop yield and rainfall for the entire crop cycle, from tasseling to 30 days after, and from 5 days before tasseling to 40 days after. Close relationships between maize yield and rainfall were found, particularly during the reproductive period (45-day period comprising the flowering and grain filling). Relationships were closer on a regional scale than at smaller scales. Implications of the crop-rainfall relationships for crop modelling are discussed.Título em português: Rendimento de milho e chuva em diferentes escalas espaço-temporais no Sul do Brasil