Host-parasite Relationships ofBulinus globosusandB. truncatuswith Strains ofSchistosoma haematobiutm

1972 ◽  
Vol 46 (2) ◽  
pp. 185-199 ◽  
Author(s):  
G. Webbe ◽  
C. James
Keyword(s):  
Exposure Level ◽  
Infection Rates ◽  
Cercarial Production ◽  
Large Numbers ◽  
Hourly Output ◽  
Exposure Levels ◽  
The Mean ◽  
Host Parasite

It is apparent that under the conditions of the observations recorded in this study the host-parasite relationships of the two species of snails and their respective strains ofS. haematobiumexhibit marked similarity in certain respects but differ in others. Higher cercarial infection rates were obtained inB. globosusthan inB. truncalusat relatively low miracidial exposure levels but the daily mean cercarial outputs of each species at the same miracidial exposure level were similar. A higher frequency of production of large numbers of cercariae was recorded for infividualB. globosusthan forB. truncatus. The mean cercarial prepatent periods forB. globosusandB. truncatusat a level of 7 miracidia were each 32 days, but infectedB. globosuslived appreciably longer than infectedB. truncatus. The hourly output of both species exposed to stimuli for the same period of time was broadly similar. Peaks of cercarial production were generally reached earlier by individualB. truncatus(2 weeks) after onset of shedding than by individualB. globosus(4–5 weeks), although erratic shedding was observed for both species.

Studies of the relationships between Schistosoma nasale and S. spindale and their snail host Indoplanorbis exustus

1991 ◽  
Vol 65 (1) ◽  
pp. 1-7 ◽  
Author(s):  
J. de Bont ◽  
J. Vercruysse ◽  
D. van Aken ◽  
V. R. Southgate ◽  
D. Rollinson
Keyword(s):  
Sri Lanka ◽  
Intermediate Host ◽  
Snail Host ◽  
Infection Rates ◽  
Death Rates ◽  
Cercarial Production ◽  
Indoplanorbis Exustus ◽  
Level 1 ◽  
Host Parasite ◽  
Opposite Tendency

ABSTRACTInfectivity and cercarial production of Indoplanorbis exustus related to variation of miracidial dose (1, 4, 10 or 20) with Schistosoma nasale and S. spindale from Sri Lanka were studied. The intermediate host-parasite relationships of the two schistosome species showed marked differences under the conditions of observation recorded in this study. Prepatent death rates (PDR) were on average higher for S. spindale (30%) than for S. nasale (10%). The size of the miracidial dose to which snails had been exposed had no effect on PDR. The infection rates (IR) were on average higher for S. nasale (41%) compared with S. spindale (27%). Highest IR occurred after exposure to 4 miracidia in S. nasale infections (79%) and after exposure to 10 miracidia in S. spindale infections (6O%). The highest daily average cercarial production per snail was recorded for S. nasale at a level of 4 miracidia (1311), and for S. spindale at a level of 10 miracidia (1615). At low level (1 or 4 miracidia) of exposure, I. exustus showed a better compatibility with S. nasale than with S. spindale. An opposite tendency was observed at higher levels (10 or 20 miracidia) of exposure. Unsuccessful infections of Lymnaea luteola with either S. nasale or S. spindale indicate that this species is not involved in transmission.

scholarly journals Occupational Noise Exposure of Traffic Enforcers in Selected Streets in the City of Manila

2018 ◽  
Vol 52 (3) ◽  
Author(s):  
Louise Elinor R. Dulay ◽  
Ma. Danica Katrina P. Galvan ◽  
Rio Joana M. Puyaoan ◽  
Angel Abraham Y. Sison ◽  
Nicole S. Natanauan ◽  
...  
Keyword(s):  
Occupational Safety ◽  
Sound Pressure ◽  
Noise Exposure ◽  
Occupational Safety And Health ◽  
Exposure Level ◽  
Safety And Health ◽  
Health Standards ◽  
Exposure Levels ◽  
The Mean ◽  
The City

Objective. The study aimed to evaluate the sound pressure levels of selected traffic enforcer sites in the City of Manila. Methods. A Brüel & Kjær Integrating Sound Level Meter type 2225 was used to measure sound pressure levels in dB(A) to estimate personal noise exposure of traffic enforcers designated at Quezon Boulevard near Quiapo Church and Recto – Rizal Avenue on a weekday and a weekend. Graphs were generated while appropriate measures were calculated for the noise exposure levels. The mean exposure levels were compared with the Philippine Occupational Safety and Health standards by computing the corresponding permissible exposure limit for each work shift using the Equal Energy Principle.17 Results. Noise exposure levels at Quezon Boulevard ranged from 75.0 dB(A) to 91.5 dB(A) with mean noise exposure level of 84.3 ± 3.7 dB(A) and 82.5 ± 2.6 dB(A) for the weekday AM and PM shift, respectively. The mean noise exposure level at Quezon Boulevard for the weekend AM shift was 82.4 ± 2.6, whereas 80.4 ± 2.8 for the PM shift. The noise exposure levels at Recto – Rizal Avenue ranged from 81.5 dB(A) to 99.3 dB(A) with mean noise exposure level of 86.7 ± 2.6 dB(A) and 86.0 ± 2.1 dB(A) for the weekday AM and PM shift, respectively. The mean noise exposure level at Recto – Rizal Avenue for the weekend AM shift was 86.7 ± 2.3, whereas 89.0 ± 4.0 for the PM shift. Conclusion. The study showed that traffic enforcers designated at Quezon Boulevard and Recto – Rizal Avenue are exposed to noise levels that do not exceed the Philippine Occupational Safety and Health standards.

scholarly journals Assessment of Outdoor Gamma Exposure Level of Some Swampy Agricultural Soils of Nasarawa West, Nigeria

2021 ◽  
pp. 32-41
Author(s):  
Abdullahi A. Mundi ◽  
Idris M. Mustapha ◽  
Rabo Maikeffi
Keyword(s):  
Agricultural Soils ◽  
Nuclear Radiation ◽  
Exposure Level ◽  
Radiological Hazard ◽  
Lifetime Cancer Risk ◽  
Mean Values ◽  
Permissible Limits ◽  
Background Exposure ◽  
Exposure Levels ◽  
The Mean

In this study, assessment of outdoor background exposure levels in some selected swampy agricultural soil in Nasarawa West, Nigeria has been conducted. An in-situ measurement of outdoor background exposure rate (in mRhr-1) for a total of fifty farms (ten each from Keffi (KF), Kokona (KK), Karu (KR), Toto (TT), and Nasarawa (NS))  were  done  using  a  well  calibrated  portable  halogen-quenched  Geiger  Muller  (GM)  detector (Inspector alert Nuclear radiation monitor SN:3544). A geographical positioning system (GPS) was used at an elevation of 1.0 m above ground level to obtain the geographical location.  The radiological hazard parameters were evaluated using the measured outdoor background exposure rates.  The values obtained were compared with recommended permissible limits to ascertain the radiological hazard status of the swampy agricultural farms.  The  mean  values  of  the  outdoor  background  exposure  levels (0.23, 0.038, 0.028, 0.022, and 0.039 mRh-1), absorbed dose rates (458.49, 334.95, 188.79, 194.01,  and 343.65 nGyh-1) and excess lifetime cancer risk (1.968, 1438, 0.810, 0.832, and 1.475)  each for KF, KK, KR, TT, and NS respectively, are higher than the  recommended  safe  limits  of  0.013  mRh-1,  84.0  nGyh-1,  0.00029 respectively  as  recommended by UNSCEAR and ICRP. On the other hand, the mean annual effective dose equivalent (AEDE) values (0.563, 0.410, 0.232, 0.238, and 0.421 mSvy-1 for KF, KK, KR, TT, and NS respectively) are below the recommended permissible limits of 1.00 mSvy-1 for general public exposure. Generally, the study revealed that swampy agricultural soils in Nasarawa west are radiologically safe with little contamination which could be attributed to the geological formation and partly due to human activity in the area.

RF-EMF EXPOSURE LEVELS IN SENSITIVE LAND USE IN GREECE: EDUCATIONAL UNITS CENSUS IN THE MUNICIPALITY OF KORYDALLOS

2020 ◽  
Vol 190 (2) ◽  
pp. 193-199
Author(s):  
Aris Alexias ◽  
Yiannis Kiouvrekis ◽  
Vasiliki Softa ◽  
Constantin Kappas ◽  
Charilaos Tyrakis ◽  
...  
Keyword(s):  
Land Use ◽  
Mobile Phones ◽  
Mean Value ◽  
Exposure Level ◽  
Limit Set ◽  
Exposure Limits ◽  
Primary And Secondary Education ◽  
Exposure Levels ◽  
The Mean

Abstract Background The growing popularity of mobile phones and the expansion of network infrastructure in Greece have raised concerns about the possible negative health effects on sensitive groups, such as children, from exposure to long-term radiofrequency electromagnetic fields (RF-EMFs). Aims The objective of this study is to estimate mean RF-EMF exposure levels of primary and secondary education schools located in the municipality of Korydallos, Athens, Greece. Methods We performed measurements to all the schools units ($n=62$) in the region in order to calculate the mean value for RF-EMF exposure in the range of 27 MHz–3 GHz, which covers the whole spectrum of RF-EMF sources. Results At the $97.5\%$ of schools found in Korydallos region, the exposure level is at least 2200 times below the Greek exposure limits. Conclusion The exposure levels in the locations tested are both below $60\%$ of the highest limit set by the International Commission on Non-Ionizing Radiation Protection regarding school exposures.

scholarly journals Biomonitoring Study of Deoxynivalenol Exposure in Chinese Inhabitants

2019 ◽  
Vol 16 (12) ◽  
pp. 2169 ◽  
Author(s):  
Xiaodan Wang ◽  
Jiang Liang ◽  
Pei Cao ◽  
Shuang Zhou ◽  
Aibo Wu ◽  
...  
Keyword(s):  
Children And Adolescents ◽  
High Performance ◽  
Age Groups ◽  
Henan Province ◽  
Urine Samples ◽  
Exposure Level ◽  
Dietary Intakes ◽  
Liquid Chromatography Tandem Mass ◽  
Exposure Levels ◽  
The Mean

Objective: To investigate the levels of a deoxynivalenol (DON) biomarker in the urine of subjects living in two China provinces with different geographic locations and dietary patterns, and estimate their dietary DON exposures and health risks. Methods: First morning urine samples were collected on three consecutive days from 599 healthy subjects—301 from Henan province and 298 from Sichuan province—to analyze the total DON concentrations (tDON) after β-glucuronidase hydrolysis using a high-performance liquid chromatography tandem mass spectrometry-based method. The consumption of cereal foods in the previous 24 h before each urine collection was recorded using a duplicate diet method. DON exposure levels were estimated based on the urinary tDON concentrations. Results: Total DON were detected in 100% and 92% of the urine samples from Henan and Sichuan, respectively. Mean urinary tDON concentrations were 52.83 ng/mL in Henan subjects and 12.99 ng/mL in Sichuan subjects, respectively. The tDON levels were significantly higher in the urine of Henan subjects than that of the Sichuan subjects (p < 0.001). Urinary tDON levels were significantly different among age groups in both areas (Henan: p < 0.001; Sichuan: p = 0.026) and were highest in adolescents aged 13–17 years, followed by children aged 7–12 years. Based on the DON biomarker and exposure conversion reported by the European Food Safety Authority (EFSA), the mean estimated dietary intakes of DON were 1.82 μg/kg bw/day in Henan subjects and 0.45 μg/kg bw/day in Sichuan subjects. A total of 56% of Henan subjects and 12% of Sichuan subjects were estimated to exceed the PMTDI of 1 μg/kg bw/day. Consistent with urinary tDON levels, the highest estimated dietary DON intakes were also in children and adolescents aged 7–17 years. For all kinds of wheat-based foods except dumplings, the consumptions were significantly higher in Henan than those in Sichuan. The mean consumption of steamed buns was 8.4-fold higher in Henan (70.67 g/d) than that in Sichuan (8.45 g/d). The mean consumption of noodles in Henan (273.91 g/d) was 3.6-fold higher than that in Sichuan (75.87 g/d). Conclusions: The levels of urinary DON biomarker and the estimated dietary DON intakes in Henan province were high and concerning, especially for children and adolescents. The overall exposure level of Sichuan inhabitants was low.

scholarly journals Characteristics of Occupational Exposure to Diesel Engine Exhaust for Shipyard Transporter Signal Workers

2020 ◽  
Vol 17 (12) ◽  
pp. 4398
Author(s):  
Jungah Shin ◽  
Boowook Kim ◽  
Hyoung-Ryoul Kim
Keyword(s):  
Diesel Engine ◽  
Meteorological Factors ◽  
Load Capacity ◽  
Total Carbon ◽  
International Agency ◽  
Exposure Level ◽  
Engine Exhaust ◽  
Diesel Engine Exhaust ◽  
Exposure Levels ◽  
The Mean

Background: Workers performing signal work for a heavy-duty shipyard transporter are exposed to diesel engine exhaust (DEE), which is classified as a Group 1 carcinogen by the International Agency for Research on Cancer. Here, we evaluate DEE exposure levels for workers engaged in shipyard transporter signal work through measurement of respirable elemental carbon (EC), organic carbon (OC), and total carbon (TC), and identify the factors affecting exposure. Methods: Sixty signal workers were selected, and measured samples were analyzed by thermo-optical transmittance. Results: The mean EC exposure level of a transporter signal worker was 4.16 µg/m3, with a range of 0.69 to 47.81 µg/m3. EC, OC, and TC exposure levels did not show statistically significant differences for individual variables except the measurement date. This was influenced by meteorological factors such as wind speed, and it was confirmed that the work position, number carried, and load capacity in the multiple regression analysis after minimizing the meteorological effects were factors influencing the EC exposure level of the signalman. Conclusions: Meteorological conditions influenced DEE exposure of transporter signal workers who work outdoors. The mean EC exposure level was not high, but exposures to high concentrations of EC were recorded by meteorological factors.

scholarly journals Relaxation Times in Strictly Disk Systems

1971 ◽  
Vol 10 ◽  
pp. 15-19
Author(s):  
George B. Rybicki
Keyword(s):  
Numerical Experiments ◽  
Relaxation Times ◽  
Galactic Structure ◽  
Large Numbers ◽  
Order Of Magnitude ◽  
Vlasov Limit ◽  
The Mean ◽  
Gravitating Systems

AbstractIt is shown that the time of relaxation by particle encounters of self-gravitating systems in the plane interacting by 1/r2 forces is of the same order of magnitude as the mean orbit time. Therefore such a system does not have a Vlasov limit for large numbers of particles, unless appeal is made to some non-zero thickness of the disk. The relevance of this result to numerical experiments on galactic structure is discussed.

External Ventricular Drain Infection

2007 ◽  
Vol 107 (1) ◽  
pp. 248 ◽  
Author(s):  
George K. C. Wong ◽  
Wayne W. S. Poon
Keyword(s):  
Major Trauma ◽  
Independent Predictor ◽  
External Ventricular Drain ◽  
Significant Risk ◽  
Significant Risk Factor ◽  
External Ventricular Drainage ◽  
Infection Rates ◽  
The Mean ◽  
The Relationship ◽  
Shed Light

Object The authors explored the relationship among the duration of external ventricular drainage, revision of external ventricular drains (EVDs), and cerebrospinal fluid (CSF) infection to shed light on the practice of electively revising these drains. Methods In a retrospective study of 199 patients with 269 EVDs in the intensive care unit at a major trauma center in Australasia, the authors found 21 CSF infections. Acinetobacter accounted for 10 (48%) of these infections. Whereas the duration of drainage was not an independent predictor of infection, multiple insertions of EVDs was a significant risk factor. Second and third EVDs in previously uninfected patients were more likely to become infected than first EVDs. An EVD infection was initially identified a mean of 5.5 ±0.7 days postinsertion (standard error of the mean); these data—that is, the number of days—were normally distributed. Conclusions This pattern of infection is best explained by EVD-associated CSF infections being acquired by the introduction of bacteria on insertion of the drain rather than by subsequent retrograde colonization. Elective EVD revision would be expected to increase infection rates in light of these results, and thus the practice has been abandoned by the authors' institution.

GLOBAL FLUCTUATIONS FOR LINEAR STATISTICS OF β-JACOBI ENSEMBLES

2012 ◽  
Vol 01 (04) ◽  
pp. 1250013 ◽  
Author(s):  
IOANA DUMITRIU ◽  
ELLIOT PAQUETTE
Keyword(s):  
Gaussian Process ◽  
Covariance Matrix ◽  
Law Of Large Numbers ◽  
Test Functions ◽  
Linear Statistics ◽  
Jacobi Ensemble ◽  
Large Numbers ◽  
The Mean ◽  
Shifted Chebyshev Polynomial ◽  
Global Fluctuations

We study the global fluctuations for linear statistics of the form [Formula: see text] as n → ∞, for C1 functions f, and λ1, …, λn being the eigenvalues of a (general) β-Jacobi ensemble. The fluctuation from the mean [Formula: see text] turns out to be given asymptotically by a Gaussian process. We compute the covariance matrix for the process and show that it is diagonalized by a shifted Chebyshev polynomial basis; in addition, we analyze the deviation from the predicted mean for polynomial test functions, and we obtain a law of large numbers.

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