Browsing by Subject "Detection"

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  • Lahtela, Eero (Helsingin yliopisto, 2021)
    Municipal environmental authorities are required to conduct environmental monitoring. Unmanned aerial vehicles, UAVs, may be helpful in environmental monitoring but their applicability as a tool for municipal environmental monitoring has not been studied. In this thesis it was studied, how municipalities have been utilizing UAVs. Additionally, UAVs applicability for environmental monitoring and inspection work was tested using a litter monitoring experiment as an example. In the first part of the study, a questionnaire was sent to municipal environmental authorities in Finland, to municipalities in Sweden and to those participating in Eurocities WG Waste group (n = 512), covering the used applications, their utilization frequencies and successfulness, reasons for failures and future plans. The results were analyzed using descriptive statistics. In the second part of the study, a UAV was utilized in a litter monitoring experiment on four sites in Helsinki. Litter by category and leaves were counted based on visual observations from UAV imagery. The accuracy of UAV imagery detection was assessed by comparing its and ground assessment (GA) results. On one site, a control group also carried out UAV imagery detections in order to assess the magnitude of bias or offset occurring when both the GA and the litter detection from UAV imagery are conducted by a single individual. The Wilcoxon signed rank and Cronbach’s α reliability tests were used for statistical analysis of the results. Response rate of the questionnaire was low, 3.7% (n = 19). The pool of used applications was extensive and covered a variety of monitoring and inspecting targets with emphasis on the presumably manually piloted applications. Utilization was very successful. The most important reasons for failures were poor weather followed by lack of information and expertise. UAVs were included in the future plans of most participants for municipal environmental monitoring purposes. The UAV imagery detection accuracies of litter and leaves compared to the GA results were high, 90.5% for litter and 87.5% for litter and leaves, and no statistically significant differences existed between the assessment results. Especially leaves proved challenging to detect from UAV imagery. The control group’s detection accuracies were 67.9% without and 49.0% with leaves, and with leaves the results differed with statistical significance (p = 0.028). The internal reliability of the control group was relatively high, α = 0.776 without and α = 0.805 with leaves. UAVs are deemed sufficiently accurate and versatile as monitoring and inspecting tools for municipal environmental authorities. They have the capability to complement ground assessments or, with certain prerequisites, even function as an independent monitoring method. Further application and detection method development and research on municipal UAV utilization are needed.
  • Osemwowa, Etinosa; Omoruyi, Iyekhoetin Matthew; Kurittu, Paula; Heikinheimo, Annamari; Fredriksson-Ahomaa, Maria (2021)
    Beef can easily be contaminated with bacteria during the meat production chain. In this work, we studied the contamination levels of mesophilic aerobic bacteria (MAB) and thermotolerant coliform bacteria (TCB) on raw beef surfaces from small shops in Helsinki, Finland and meat markets in Benin City, Nigeria. We also investigated the prevalence of Salmonella, Campylobacter, Yersinia, Shiga toxin-producing Escherichia coli (STEC), Listeria, and cephalosporin-resistant E. coli (CREC). In total, one hundred unpacked raw beef samples from Finland and Nigeria were collected in 2019. The median MAB and TCB counts were significantly (P < 0.001) higher on beef from Nigeria than from Finland. The median MAB and TCB counts in Nigeria were 7.5 and 4.0 log10 cfu/cm2, respectively, and 6.5 and 2.8 log10 cfu/cm2 in Finland, respectively. Most (94%) Nigerian samples were unacceptable according to limits set by the EU. Beef samples from meat markets in Benin City were significantly (P < 0.05) more frequently contaminated with Salmonella, STEC, and CREC than beef samples from small shops in Helsinki. Salmonella, STEC, and CREC were isolated from 30, 36, and 96% of Nigerian samples, respectively, and from
  • Alaraudanjoki, Viivi; Saarela, Henna; Pesonen, Reetta; Laitala, Marja-Liisa; Kiviahde, Heikki; Tjaderhane, Leo; Lussi, Adrian; Pesonen, Paula; Anttonen, Vuokko (2017)
    Objectives: To assess the reliability of the BEWE index on 3D models and to compare 3D-assessed erosive tooth wear scores with clinically detected scores. Methods: In total, 1964 members of the Northern Finland Birth Cohort 1966 participated in a standardized clinical dental examination including the Basic Erosive Wear Examination (BEWE) and dental 3D modelling at the age of 45-46 years. Of those examined, 586 were randomly selected for this study. 3D models were assessed using the same BEWE criteria as in the clinical examination. Calculated kappa values as well as the prevalence and severity of erosive wear according to the clinical examination and 3D models were compared. Re-examinations were performed to calculate intra-and inter-method and-examiner agreements. Results: The BEWE index on 3D models was reproducible; the mean intra-and inter-examiner agreement were 0.89 and 0.87, respectively, for sextant level, and 0.64 and 1, respectively, for BEWE sum scores. Erosive tooth wear was recorded as more severe in 3D models than in the clinical examination, and intermethod agreement was 0.41 for severe erosive wear (BEWE sum > 8). The biggest inter-method differences were found in upper posterior sextants. Conclusions: The BEWE index is reliable for recording erosive tooth wear on 3D models. 3D models seem to be especially sensitive in detecting initial erosive wear. Additionally, it seems that erosive wear may be underscored in the upper posterior sextants when assessed clinically. Due to the nature of 3D models, the assessment of erosive wear clinically and on 3D models may not be entirely comparable. Clinical significance: 3D models can serve as an additional tool to detect and document erosive wear, especially during the early stages of the condition and in assessing the progression of wear. When scoring erosive wear clinically, care must be taken especially when assessing upper posterior sextants. (C) 2017 Elsevier Ltd. All rights reserved.
  • Hallanvuo, S.; Herranen, M.; Jaakkonen, A.; Nummela, M.; Ranta, J.; Botteldoorn, N.; De Zutter, L.; Fredriksson-Ahomaa, M.; Hertwig, S.; ohannessen, G.S.; Ludewig, M.; Messelhäußer, U.; Sigvart-Mattila, P.; Thisted-Lambertz, S.; Thure, T.; Vatunen, E.; Interlaboratory study group (Elsevier, 2018)
    EN ISO 10273 method for the detection of pathogenic Yersinia enterocolitica in foods was validated in the project Mandate M/381 funded by European Commission. A total of 14 laboratories from five European countries participated in the interlaboratory study (ILS) organized during 2013 and 2014. Before the ILS, the method was revised by an international group of experts and the performance of the revised method was assessed in an ILS study. The results are published as a part of the standard EN ISO 10273 revision. The study included three rounds with different sample types; raw milk, iceberg lettuce and minced meat, inoculated with a low and high level of pathogenic Y. enterocolitica strains representing major pathogenic bioserotypes 4/O:3 and 2/O:9. The homogeneity and stability of the samples were verified before dispatching them to the laboratories. The results demonstrated the method sensitivity of 96% in raw milk, 97% in minced meat, and 98% in lettuce at high inoculation level of pathogenic Y. enterocolitica. The specificity was 100% in raw milk, 96% in minced meat, and 98% in lettuce. The level of detection, LOD50, varied between study rounds, being 9.4 CFU/25 ml in raw milk, 9.9 CFU/25 g in minced meat and 63 CFU/25 g in lettuce samples. During the study, confirmation by using real-time PCR method ISO/TS 18867 together with pyrazinamidase testing was also validated, as alternative to conventional biochemical confirmation. When comparing different isolation steps used in the revised method during the study rounds, PSB enrichment and plating on CIN after alkaline (KOH) treatment showed the highest sensitivity (52–92%) in raw milk and minced meat samples. In lettuce samples, however, ITC with KOH treatment before plating on CIN showed higher sensitivity (64% at low level; 82% at high level) than plating on CIN from PSB with KOH treatment (44% at low level; 74% at high level). Statistical analysis of different isolation steps supported the use of two enrichment media, PSB and ITC, in the revised method. Recovery of pathogenic Y. enterocolitica on CIN was most efficient after KOH treatment and, based on the analysis, plating on CIN agar without KOH treatment could be left as optional procedure in the method.
  • Interlab Study Grp; Hallanvuo, Saija; Herranen, Mirkka; Jaakkonen, Anniina; Nummela, Maria; Ranta, Jukka; Botteldoornl, Nadine; De Zutter, Lieven; Fredriksson-Ahomaa, Maria; Hertwig, Stefan; Johannessen, Gro S.; Ludewig, Martina; Messelhaeusser, Ute; Sigvart-Mattila, Pia; Thisted-Lambertz, Susanne; Thure, Tiina; Vatunen, Elina (2019)
    EN ISO 10273 method for the detection of pathogenic Yersinia enterocolitica in foods was validated in the project Mandate M/381 funded by European Commission. A total of 14 laboratories from five European countries participated in the interlaboratory study (ILS) organized during 2013 and 2014. Before the ITS, the method was revised by an international group of experts and the performance of the revised method was assessed in an ILS study. The results are published as a part of the standard EN ISO 10273 revision. The study included three rounds with different sample types; raw milk, iceberg lettuce and minced meat, inoculated with a low and high level of pathogenic Y. enterocolitica strains representing major pathogenic bioserotypes 4/O:3 and 2/O:9. The homogeneity and stability of the samples were verified before dispatching them to the laboratories. The results demonstrated the method sensitivity of 96% in raw milk, 97% in minced meat, and 98% in lettuce at high inoculation level of pathogenic Y. enterocolitica. The specificity was 100% in raw milk, 96% in minced meat, and 98% in lettuce. The level of detection, LOD50, varied between study rounds, being 9.4 CFU/25 ml in raw milk, 9.9 CFU/25 g in minced meat and 63 CFU/25 g in lettuce samples. During the study, confirmation by using real-time PCR method ISO/TS 18867 together with pyrazinamidase testing was also validated, as alternative to conventional biochemical confirmation. When comparing different isolation steps used in the revised method during the study rounds, PSB enrichment and plating on CIN after alkaline (KOH) treatment showed the highest sensitivity (52-92%) in raw milk and minced meat samples. In lettuce samples, however, ITC with KOH treatment before plating on CIN showed higher sensitivity (64% at low level; 82% at high level) than plating on CIN from PSB with KOH treatment (44% at low level; 74% at high level). Statistical analysis of different isolation steps supported the use of two enrichment media, PSB and ITC, in the revised method. Recovery of pathogenic Y. enterocolitica on ON was most efficient after KOH treatment and, based on the analysis, plating on CIN agar without KOH treatment could be left as optional procedure in the method.