Auditory masking - A study of its physiological mechanism and of correlations between physiological and psychological observations First quarterly progress report, period ending 30 Jun. 1965

Psychological and physiological study of auditory maskin

Effect of duct shape, Mach number, and lining construction on measured suppressor attenuation and comparison with theory

Noise attenuation was measured for several types of cylindrical suppressors that use a duct lining composed of honeycomb cells covered with a perforated plate. The experimental technique used gave attenuation data that were repeatable and free of noise floors and other sources of error. The suppressor length, the effective acoustic diameter, suppressor shape and flow velocity were varied. The agreement among the attenuation data and two widely used analytical models was generally satisfactory. Changes were also made in the construction of the acoustic lining to measure their effect on attenuation. One of these produced a very broadband muffler

Insecticidal components in the meal of Crambe abyssinica.

The defatted seed meal of C. abyssinica was systematically analysed for insecticidal activity against Musca domestica and the active components were isolated and characterized. 2-(S)-1-Cyano-2-hydroxy-3-butene (SCHB) and phenylethyl cyanide (PEC) were identified as active components, whereas diacetone alcohol (DAA), which was identified in the extracts and tested, was not toxic to house flies. The presence of DAA and PEC in the extracts was confirmed by using gas chromatographic and mass-spectral (GC-MS) comparison with purchased reference compounds. 1,3-Benzodioxole-5-carboxaldehyde (piperonal, PIP) was also identified as a possible minor component, but was not tested. GC-MS analysis determined that the dichloromethane extract of defatted crambe seed meal contained SCHB and crambe oil at a ratio of 5:2, while DAA and PEC were present in trace amounts. Topical LD50values for M. domestica were calculated for SCHB, PEC, DAA, crude crambe extract, crambe oil and an artificial crambe extract composed of SCHB and crambe oil in the proportions found in the crude crambe extract. SCHB was found to be the most toxic major component of the crambe extract. Although SCHB concentration accounted for the toxicity of the artificial extract, the natural crambe extract was significantly less toxic than would be expected based on SCHB concentration alone. 2-(R)-1-Cyano-2-hydroxy-3-butene (RCHB), an enantiomer of SCHB which does not occur in crambe, was extracted from Brassica napus seed meal and tested as well. RCHB was found to be significantly less toxic to house flies than SCHB

Acoustic properties of a supersonic fan

Acoustic properties of supersonic fan with short blade spa

Ocean-atmosphere trajectories of extended drought in southwestern North America

Author Posting. © American Geophysical Union, 2019. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research-Atmospheres 124(16), (2019): 8953-8971, doi: 10.1029/2019JD030424.Multiyear droughts are a common occurrence in southwestern North America (SWNA), but it is unclear what causes these persistent dry periods. The ocean‐atmosphere conditions coinciding with droughts have traditionally been studied using correlation and composite methods, which suggest that cool conditions in the tropical Pacific are associated with SWNA droughts and warm conditions are associated with wet periods in SWNA. Nevertheless, the extent to which multiyear droughts are truly consistent with this paradigm remains unknown. This is, in part, because the temporal trajectory of ocean‐atmosphere conditions during these dry periods have not been sufficiently characterized. Here we examine the continuum of ocean‐atmosphere trajectories before, during, and after multiyear droughts in SWNA using observation‐based data and an ensemble of climate model simulations from the Community Earth System Model. An examination of sea surface temperature patterns at the beginning, middle, and end of SWNA droughts shows that an El Niño event tends to precede SWNA droughts, a cool tropical Pacific occurs during droughts, and central Pacific El Niño events end droughts. However, moderate El Niño events can occur in the middle of persistent droughts, so a warm tropical Pacific does not always end these dry periods. These findings are important for drought predictability and emphasize the need to improve simulations of the magnitude, life cycle, and frequency of occurrence of El Niño events.L. Parsons thanks the Washington Research Foundation for funding support and thanks R. Jnglin Wills and D. Battisti for suggestions related to tropical Pacific‐SWNA comparisons. We thank B. Otto‐Bliesner and acknowledge the CESM1(CAM5) Last Millennium Ensemble Community Project and supercomputing resources provided by NSF/CISL/Yellowstone. Support for the Twentieth Century Reanalysis Project version 2c data set is provided by the U.S. Department of Energy, Office of Science Biological and Environmental Research (BER), and by the National Oceanic and Atmospheric Administration Climate Program Office. GPCC Precipitation data provided by the NOAA/OAR/ESRL PSD, Boulder, Colorado, USA, from their Web site (https://www.esrl.noaa.gov/psd/).2020-02-0

Periodicity of high-order functions in the CNS Final progress report, year ending 30 Jun. 1971

Analysis of cerebral slow potentials underlying human attentive processes in central nervous syste

Plant essential oils synergize various pyrethroid insecticides and antagonize malathion in Aedes aegypti

Pyrethroid resistance is a significant threat to agricultural, urban and public health pest control activities. Because economic incentives for the production of novel active ingredients for the control of public health pests are lacking, this field is particularly affected by the potential failure of pyrethroid‐based insecticides brought about by increasing pyrethroid resistance. As a result, innovative approaches are desperately needed to overcome insecticide resistance, particularly in mosquitoes that transmit deadly and debilitating pathogens. Numerous studies have demonstrated the potential of plant essential oils to enhance the efficacy of pyrethroids. The toxicity of pyrethroids combined with plant oils is significantly greater than the baseline toxicity of either oils or pyrethroids applied alone, which suggests there are synergistic interactions between components of these mixtures. The present study examined the potential of eight plant essential oils applied in one of two concentrations (1% and 5%) to enhance the toxicity of various pyrethroids (permethrin, natural pyrethrins, deltamethrin and β‐cyfluthrin). The various plant essential oils enhanced the pyrethroids to differing degrees. The levels of enhancement provided by combinations of plant essential oils and pyrethroids in comparison with pyrethroids alone were calculated and synergistic outcomes characterized. Numerous plant essential oils significantly synergized a variety of pyrethroids; type I pyrethroids were synergized to a greater degree than type II pyrethroids. Eight plant essential oils significantly enhanced 24‐h mortality rates provided by permethrin and six plant essential oils enhanced 24‐h mortality rates obtained with natural pyrethrins. By contrast, only three plant essential plants significantly enhanced the toxicity of deltamethrin and β‐cyfluthrin. Of the plant essential oils that enhanced the toxicity of these pyrethroids, some produced varying levels of synergism and antagonism. Geranium, patchouli and Texas cedarwood oils produced the highest levels of synergism, displaying co‐toxicity factors of \u3e 100 in some combinations. To assess the levels of enhancement and synergism of other classes of insecticide, malathion was also applied in combination with the plant oils. Significant antagonism was provided by a majority of the plant essential oils applied in combination with this insecticide, which suggests that plant essential oils may act to inhibit the oxidative activation processes within exposed adult mosquitoes