A study of the effectiveness of an after-school peer tutoring/homework help program

The purpose of this study was to determine if the students in the after-school peer tutoring/homework help club made greater academic gains when compared to students who did not participate in the after-school program as measured by their grade point average. The subjects of this study were 30 fifth, sixth, and seventh grade students from a one school district in a rural southern New Jersey town. Fifteen students were enrolled in the after-school program. Fifteen students did not attend the after-school program. Grade point averages were calculated for both groups at the end of marking periods one and two. A comparison was made both within the treatment group and between the treatment group and the control group to determine the difference in gains made by each group. Results indicate a positive mean gain within the treatment group. Mean grade point averages increased as the number of sessions increased. Although the mean grade point average of the treatment group fell below that of the control group, the control group did not indicate any positive gains. The findings of this study indicate no meaningful difference in the gains made by the treatment group. The treatment group made positive gains with no regression in either group

Evaluation of stretch film behavior during long-term storage under different atmospheric conditions

This study examined the post-application behavior of two 20.3 micron machine stretch films, one categorized as high-performance and one as general-performance, for thirty days while stored at either 23°C or 38°C. For each film type, the stretch film was applied to a simulated unit load to produce neutral and positive applied total stretch scenarios. The relaxation curves developed from each test indicate the relaxation rate of the films varied based on the storage condition. Observed was an average of 41% containment loss for both high-performance and general-purpose films when the simulated loads were stored at 38°C. For simulated loads stored at 23°C, the reported average containment loss for both films was 26%. The application of the film, either neutral or positive, did not greatly affect the percent loss in containment for the film. Additionally, results showed the greatest amount of containment force loss occurred during the initial 2 h of storage for all 23°C treated samples and 38°C general-purpose treated samples, while 38°C high-performance films continued to relax for 7 days until no difference was observed

Profesionalno oštećenje vanadijumom

Es werden industrielle Gesundheitsschaden durch Vanadin dargestellt. 7 Fälle mit Dauerschaden sind beschrieben. Nachuntersuchungen bei einschlägigen Arbeitern führten zu dem Ergebnis, dass durch Änderung des technischen Verfahrens Gesundheitsstörungen weitgehend eingeschränkt werden können.U toku posljednjih petnaest godina znatno se povećala upotreba vanadijuma u industriji. Autor je već 1939. god. opisao karakteristična profesionalna oštećenja. Od tog su vremena postojala o toksičnosti vanadijuma vrlo nejasna i često suprotna mišljenja pojedinih autora. Vanadijumska kiselina, koja nastaje u toku kemijskog i tehničkog procesa preradbe, djeluje štetno na zdravlje. Ona ne izaziva resorptivno toksične promjene, nego karakteristična oštećenja sluznice očiju i dišnih putova. Katkad dolazi i do pneumonije s karakterističnim jezikom crnozelene boje (vjerojatno se radi o taloženju vanadijumskog hidroksida). Opažene su i alergične promjene kože. Posljednjih su godina i drugi autori potvrdili spomenule nalaze, a opaženi su i neki drugi faktori. koji govore za profesionalno oštećenje. Autor je naknadnim istraživanjem došao do zaključka, da se promjenom tehničkog procesa može znatno smanjiti opasnost upotrebe vanadijuma u industriji. Kod ljudi, koji su duže vrijeme bili na jako eksponiranim mjestima, nastaju trajne promjene u oblik-u emfizema sa svim njegovim komplikacijama

Time Series Behavior of Occupation Exposure Data

Prior studies have observed that exposure variability increased as a function of sampling duration and attributed this phenomenon to autocorrelation. This study confirmed such behavior in occupational exposure data after controlling for factors likely to contribute to variability and assessed the impact of non-stationarity, as well as autocorrelation, on the results. Consecutive shift-long exposure measurements for 54 workers from five different data sets in 149 time series were analyzed to evaluate the variance as the interval between measurements increased. When the data were combined a clear increasing trend in the variance was observed with lag. However, a breakdown by data set revealed that the trend was present in only one of the five data sets. The effect was further isolated to 42% of the workers who contributed data and to less than 1/3 of the total number of time series analyzed. Autocorrelation and non-stationary behavior explained the increase in 60% of the time series where the trend was evident. Analysis of the entire database revealed that a small percentage of time series produced significant first-order autocorrelation coefficients or were non-stationary over the interval in which sampling was conducted. If these results are typical of other workplaces, sampling strategies may not need to address problems associated with autocorrelation or nonstationarity.Master of Science in Public Healt

Assessment of water use for estimating exposure to tap water contaminants.

Epidemiological studies examining the association between exposure to tap water contaminants (such as chlorination by-products) and disease outcomes (such as cancer and adverse reproductive outcomes) have been limited by inaccurate exposure assessment. Failure to take into account the variation in beverage and tap water consumption and exposure to volatile contaminants through inhalation and dermal absorption can introduce misclassification in assessing the association between exposure to tap water contaminants and health. To refine exposure assessment of tap water contaminants, we describe in detail the tap water consumption, showering, and bathing habits of pregnant women and their male partners as assessed by a questionnaire and a 3-day water diary. We found good agreement between questionnaire and 3-day water diary values for drinking water intake (Pearson's r = 0.78) and for time spent showering(r = 0.68) and bathing (r = 0.78). Half of the participants consumed tap water on a regular basis with an overall mean +/- 1 standard deviation (SD) of 0. 78 +/- 0.51 l/day. Our results further suggest that full-time employees, compared to women working part-time or less, have more heterogeneous consumption patterns over time. Seventy-nine percent of women and 94% of men took showers for an average of 11.6 +/-4.0 min and 10.4 +/- 4.8 min, respectively. Baths were taken more frequently by women than men (21% vs. 3%) for an average of 22.9 +/-10.1 min and 21.3 +/- 12.4 min, respectively. Thus, these patterns of tap water use should be considered in the design and interpretation of environmental epidemiology studies

Fluor as a problem of general hygiene and occupational medicine

Fluor je problem općehigijenskog i industrijsko-medicinskog značenja. Tri je poglavlja prikazano, prvo, kako je fluor važan za pučanstvo, pogotovu u pogledu zubne njege, drugo, kako prirodno i industrijsko razvijanje fluora zna u nekim krajevima ugroziti živa bića, i konačno treće, kako fluor kod izvjesnih vrsta radnika može izazvati specifično profesionalno oboljenje.Chapter I discusses fluor in connection with its bioenic properties. It is one of the biogenic elements whose traces we find in most living creatures. The part fluor plays in the prevention of dental caries is well known. The article sets forth the alfinity of fluor with genetic tooth tissue and in this connection it is stressed that fluor does not exerce its action on milk-teeth and teeth ill old age. Many instances are given to illustrate the importance of fluor in the prophylaxis of dental caries through fluorization of drinking water. Chapter II deals with acute and chronic fluor poisoning of men, animals and plants. Clinical observations were confirmed by animal tests. Chapter Ill puts forward the importance of fluor in professional pathology. Changes caused by fluor were first observed in 1932 as osteosclerosis (fluorosis) in workers engaged in the production of criolite. Since then many findings all over the world have confirmed the noxiousness of fluor. Occupational fluorosis appearing in most cases as an affection of bones shows, in the first stage, irregularities in bone formation: the bony trabeculac in the spongy substance arc thickened causing blurred contours in X-ray pictures. In the second stage the thickening of the trabeculae progresses and partly unclear, homogeneous shades can be seen. There appear periosteal layers and growths. The connecting parts of tendons are calcified. The bony substance of hollow bones thickens and the medullary cavities narrow down. In the third stage the bone structure is hardly distinguishably. Eburnation set, in. accompanied by periosteal growths and progressive calcification of the connecting tissues of tendons and ligaments. All these changes are particularly apparent in the pelvis and in the lumbal part of the vertebral column. A good prophylactic measure is a change of working place after five years of work in an exposed position and X-ray examinations every three years. The author mentions the American regulations concerning the maximal concentrations of fluor dust in workshops (0.2-0.3 mg/m3 air), Close collaboration of hygienists. health workers, labour inspectors and technical experts is commendable in order to organize protection from Fluor poisonings. In most countries damages caused by fluor rank among occupational diseases entailing a right to compensation

Kriged and modeled ambient air levels of benzene in an urban environment: an exposure assessment study

<p>Abstract</p> <p>Background</p> <p>There is increasing concern regarding the potential adverse health effects of air pollution, particularly hazardous air pollutants (HAPs). However, quantifying exposure to these pollutants is problematic.</p> <p>Objective</p> <p>Our goal was to explore the utility of kriging, a spatial interpolation method, for exposure assessment in epidemiologic studies of HAPs. We used benzene as an example and compared census tract-level kriged predictions to estimates obtained from the 1999 U.S. EPA National Air Toxics Assessment (NATA), Assessment System for Population Exposure Nationwide (ASPEN) model.</p> <p>Methods</p> <p>Kriged predictions were generated for 649 census tracts in Harris County, Texas using estimates of annual benzene air concentrations from 17 monitoring sites operating in Harris and surrounding counties from 1998 to 2000. Year 1999 ASPEN modeled estimates were also obtained for each census tract. Spearman rank correlation analyses were performed on the modeled and kriged benzene levels. Weighted kappa statistics were computed to assess agreement between discretized kriged and modeled estimates of ambient air levels of benzene.</p> <p>Results</p> <p>There was modest correlation between the predicted and modeled values across census tracts. Overall, 56.2%, 40.7%, 31.5% and 28.2% of census tracts were classified as having 'low', 'medium-low', 'medium-high' and 'high' ambient air levels of benzene, respectively, comparing predicted and modeled benzene levels. The weighted kappa statistic was 0.26 (95% confidence interval (CI) = 0.20, 0.31), indicating poor agreement between the two methods.</p> <p>Conclusions</p> <p>There was a lack of concordance between predicted and modeled ambient air levels of benzene. Applying methods of spatial interpolation for assessing exposure to ambient air pollutants in health effect studies is hindered by the placement and number of existing stationary monitors collecting HAP data. Routine monitoring needs to be expanded if we are to use these data to better assess environmental health risks in the future.</p