Acoustic Compaction Layer Detection

ABSTRACT. The ASAE standardized tool to detect the depth and strength of compaction layers in the field is the cone penetrometer. Since this method is point-to-point, researchers have experimented with on-the-fly alternatives that can be used as, or in combination with, a standard tillage tool. On-the-fly compaction layer sensing also enables adaptive tillage, where the soil is only tilled as deep as necessary, which can lead to significant energy savings and erosion reduction. Wedged tips, strain gauges mounted on a deflecting tine, air bubbles pushed into the soil, as well as ground-penetrating radar have been tested for this purpose. In this research, passive acoustics was used to detect the compaction layer by recording the sound of a cone being drawn through the soil. The premise was that a more compacted layer should cause higher sound levels, which might reveal the depth and strength of the compaction layer. Two experiments were conducted in the soil bins of the USDA-ARS National Soil Dynamics Laboratory in Auburn, Alabama. First, constant-depth tests (15 and 30 cm) at three compaction levels (0.72, 2.8, and 3.6 MPa) revealed the relationship of sound amplitude with depth and compaction. Second, to test the detection capability, the cone was gradually inserted in the soil, passing through an artificial compaction layer. A windowed, short-time Fourier transform (STFT) analysis showed that the compaction layer is detectable since the sound amplitude was positively related to depth and compaction levels, but only in the highest frequency range of the spectrum. This led to the conjecture that the soil-cone interface acts as a low-pass filtering mechanism, where the cutoff frequency becomes higher in the compaction layer due to a more intimate contact between sensor and soil

Survey of nasal carriage of Staphylococcus aureus and intestinal parasites among food handlers working at Gondar University, Northwest Ethiopia

<p>Abstract</p> <p>Background</p> <p>Food borne disease are major health problems in developing countries like Ethiopia. Food handlers with poor personal hygiene working in food establishments could be potential sources of disease due to pathogenic organisms. However; information on disease prevalence among food handlers working in University of Gondar cafeterias are very scarce. The aim of this study is to assess the prevalence of nasal carriage of <it>Staphylococcus aureus</it>, their drug resistance pattern and prevalence of intestinal parasites among food handlers working in University of Gondar student’s cafeterias.</p> <p>Method</p> <p>A cross sectional study was conducted among food handlers working in University of Gondar student’s cafeterias. A pretested structured questionnaire was used for collecting data. Nasal swab and stool were investigated for <it>S. aureus</it> and intestinal parasites; respectively as per the standard of the laboratory methods.</p> <p>Results</p> <p>Among 200 food handlers, females comprised 171(85.5%). The majority (67.5%) of the food-handlers were young adults aged 18–39 years. One hundred ninety four (97%) of the food handlers were not certified as a food handler. Forty one (20.5%) food handlers were positive for nasal carriage of S. aureus, of these 4(9.8%) was resistant for methicilin. <it>Giardia lamblia</it> was the most prevalent parasites 22 (11%), followed by <it>Ascaris lumbricoides</it> 13(6.5%), <it>Entamoeba histolytica</it> 12 (6%), <it>Strongyloides stercolaris</it> (0.5), <it>Taenia species</it> 1(0.5%) and <it>Schistosoma mansoni</it> 1(0.5%).</p> <p>Conclusion</p> <p>The finding stressed that food handlers with different pathogenic micro organisms may pose significant risk on the consumers. Higher officials should implement food handler’s training on food safety, periodic medical checkup and continuous monitoring of personal hygiene of food handlers.</p