Incorporation of Real-Time PCR into Routine Public Health Surveillance of Culture Negative Bacterial Meningitis in Sao Paulo, Brazil

Real-time (RT)-PCR increases diagnostic yield for bacterial meningitis and is ideal for incorporation into routine surveillance in a developing country. We validated a multiplex RT-PCR assay for Streptococcus pneumoniae, Neisseria meningitidis, and Haemophilus influenzae in Brazil. Risk factors for being culture-negative, RT-PCR positive were determined. The sensitivity of RT-PCR in cerebrospinal fluid (CSF) was 100% (95% confidence limits, 96.0%-100%) for N. meningitidis, 97.8% (85.5%-99.9%) for S. pneumoniae, and 66.7% (9.4%-99.2%) for H. influenzae. Specificity ranged from 98.9% to 100%. Addition of RT-PCR to routine microbiologic methods increased the yield for detection of S. pneumoniae, N. meningitidis, and H. influenzae cases by 52%, 85%, and 20%, respectively. The main risk factor for being culture negative and RT-PCR positive was presence of antibiotic in CSF (odds ratio 12.2, 95% CI 5.9-25.0). RT-PCR using CSF was highly sensitive and specific and substantially added to measures of meningitis disease burden when incorporated into routine public health surveillance in Brazil.

Low urinary 6-sulphatoxymelatonin concentrations in acute migraine

Substantial evidence points to melatonin as playing a role in the regulation of circadian rhythms, sleep, and headache disorders. The objective of the study was to assess 6-sulphatoxymelatonin (aMT6s) levels in a large consecutive series of patients with migraine, comparing with controls. A total of 220 subjects were evaluated-146 had migraine and 74 were control subjects. Urinary samples were collected into the same plastic container since 8:00 p.m. to 8:00 a.m. of the next day (12-h period) and aMT6s was measured with quantitative ELISA technique. Among patients with migraine, 53% presented pain on the day of the urine samples collection. Their urinary aMT6s concentration was significantly lower than in the urine of patients without pain [14.0 +/- 7.3 vs. 49.4 +/- 19.0; t(143) = -15.1; 95% CI = -40.0 to -30.8; P<0.001]. There was no significant difference in the aMT6s concentration of patients with migraine without pain on the day of their urine samples collection and controls [49.4 +/- 19.0 vs. 42.5 +/- 27.9; t(140) = 1.7; 95% CI = -1.2 to 14.8; P = 0.094]. To our knowledge, this is the first study to demonstrate reduction in melatonin levels during attacks in episodic and chronic migraine.

Maternal diabetes affects cell proliferation in developing rat placenta

Placentation starts with the formation of a spheroidal trophoblastic shell surrounding the embryo, thus facilitating both implantation into the uterine stroma and contact with maternal blood. Although it is known that diabetes increases the placental size and weight, the mechanisms responsible for this alteration are still poorly understood. In mammals, cellular proliferation occurs in parallel to placental development and it is possible that diabetes induces abnormal uncontrolled cell proliferation in the placenta similar to that seen in other organs (e.g. retina). To test this hypothesis, the objective of this work was to determine cell proliferation in different regions of the placenta during its development in a diabetic rat model. Accordingly, diabetes was induced on day 2 of pregnancy in Wistar rats by a single injection of alloxan (40 mg/kg i.v.). Placentas were collected on days 14, 17, and 20 postcoitum. Immunoperoxidase was used to identify Ki67 nuclear antigen in placental sections. The number of proliferating cells was determined in the total placental area as well as in the labyrinth, spongiotrophoblast and giant trophoblast cell regions. During the course of pregnancy, the number of Ki67 positive cells decreased in both control and diabetic rat placentas. However, starting from day 17 of pregnancy, the number of Ki67 positive cells in the labyrinth and spongiotrophoblast regions was higher in diabetic rat placentas as compared to control. The present results demonstrate that placentas from the diabetic rat model have a significantly higher number of proliferating cells in specific regions of the placenta and at defined developmental stages. It is possible that this increased cell proliferation promotes thickness of the placental barrier consequently affecting the normal maternal-fetal exchanges.

A systematic review with procedural assessments and meta-analysis of Low Level Laser Therapy in lateral elbow tendinopathy (tennis elbow)

Background: Recent reviews have indicated that low level level laser therapy (LLLT) is ineffective in lateral elbow tendinopathy (LET) without assessing validity of treatment procedures and doses or the influence of prior steroid injections. Methods: Systematic review with meta-analysis, with primary outcome measures of pain relief and/or global improvement and subgroup analyses of methodological quality, wavelengths and treatment procedures. Results: 18 randomised placebo-controlled trials (RCTs) were identified with 13 RCTs (730 patients) meeting the criteria for meta-analysis. 12 RCTs satisfied half or more of the methodological criteria. Publication bias was detected by Egger's graphical test, which showed a negative direction of bias. Ten of the trials included patients with poor prognosis caused by failed steroid injections or other treatment failures, or long symptom duration or severe baseline pain. The weighted mean difference (WMD) for pain relief was 10.2 mm [95% CI: 3.0 to 17.5] and the RR for global improvement was 1.36 [1.16 to 1.60]. Trials which targeted acupuncture points reported negative results, as did trials with wavelengths 820, 830 and 1064 nm. In a subgroup of five trials with 904 nm lasers and one trial with 632 nm wavelength where the lateral elbow tendon insertions were directly irradiated, WMD for pain relief was 17.2 mm [95% CI: 8.5 to 25.9] and 14.0 mm [95% CI: 7.4 to 20.6] respectively, while RR for global pain improvement was only reported for 904 nm at 1.53 [95% CI: 1.28 to 1.83]. LLLT doses in this subgroup ranged between 0.5 and 7.2 Joules. Secondary outcome measures of painfree grip strength, pain pressure threshold, sick leave and follow-up data from 3 to 8 weeks after the end of treatment, showed consistently significant results in favour of the same LLLT subgroup (p < 0.02). No serious side-effects were reported. Conclusion: LLLT administered with optimal doses of 904 nm and possibly 632 nm wavelengths directly to the lateral elbow tendon insertions, seem to offer short-term pain relief and less disability in LET, both alone and in conjunction with an exercise regimen. This finding contradicts the conclusions of previous reviews which failed to assess treatment procedures, wavelengths and optimal doses.

Late Entry into HIV Care: Estimated Impact on AIDS Mortality Rates in Brazil, 2003-2006

Background: Worldwide, a high proportion of HIV-infected individuals enter into HIV care late. Here, our objective was to estimate the impact that late entry into HIV care has had on AIDS mortality rates in Brazil. Methodology/Principal Findings: We analyzed data from information systems regarding HIV-infected adults who sought treatment at public health care facilities in Brazil from 2003 to 2006. We initially estimated the prevalence of late entry into HIV care, as well as the probability of death in the first 12 months, the percentage of the risk of death attributable to late entry, and the number of avoidable deaths. We subsequently adjusted the annual AIDS mortality rate by excluding such deaths. Of the 115,369 patients evaluated, 50,358 (43.6%) had entered HIV care late, and 18,002 died in the first 12 months, representing a 16.5% probability of death in the first 12 months (95% CI: 16.3-16.7). By comparing patients who entered HIV care late with those who gained timely access, we found that the risk ratio for death was 49.5 (95% CI: 45.1-54.2). The percentage of the risk of death attributable to late entry was 95.5%, translating to 17,189 potentially avoidable deaths. Averting those deaths would have lowered the 2003-2006 AIDS mortality rate by 39.5%. Including asymptomatic patients with CD4(+) T cell counts >200 and <= 350 cells/mm(3) in the group who entered HIV care late increased this proportion by 1.8%. Conclusions/Significance: In Brazil, antiretroviral drugs reduced AIDS mortality by 43%. Timely entry would reduce that rate by a similar proportion, as well as resulting in a 45.2% increase in the effectiveness of the program for HIV care. The World Health Organization recommendation that asymptomatic patients with CD4(+) T cell counts <= 350 cells/mm(3) be treated would not have a significant impact on this scenario.

Interaction between polymorphisms of the Human Leukocyte Antigen and HPV-16 Variants on the risk of invasive cervical cancer

Background: Persistent infection with oncogenic types of human papillomavirus (HPV) is the major risk factor for invasive cervical cancer (ICC), and non-European variants of HPV-16 are associated with an increased risk of persistence and ICC. HLA class II polymorphisms are also associated with genetic susceptibility to ICC. Our aim is to verify if these associations are influenced by HPV-16 variability. Methods: We characterized HPV-16 variants by PCR in 107 ICC cases, which were typed for HLA-DQA1, DRB1 and DQB1 genes and compared to 257 controls. We measured the magnitude of associations by logistic regression analysis. Results: European ( E), Asian-American ( AA) and African (Af) variants were identified. Here we show that inverse association between DQB1*05 ( adjusted odds ratio [ OR] = 0.66; 95% confidence interval [CI]: 0.39-1.12]) and HPV-16 positive ICC in our previous report was mostly attributable to AA variant carriers ( OR = 0.27; 95% CI: 0.10-0.75). We observed similar proportions of HLA DRB1*1302 carriers in E-P positive cases and controls, but interestingly, this allele was not found in AA cases ( p = 0.03, Fisher exact test). A positive association with DRB1*15 was observed in both groups of women harboring either E ( OR = 2.99; 95% CI: 1.13-7.86) or AA variants ( OR = 2.34; 95% CI: 1.00-5.46). There was an inverse association between DRB1*04 and ICC among women with HPV-16 carrying the 350T [83L] single nucleotide polymorphism in the E6 gene ( OR = 0.27; 95% CI: 0.08-0.96). An inverse association between DQB1*05 and cases carrying 350G (83V) variants was also found ( OR = 0.37; 95% CI: 0.15-0.89). Conclusion: Our results suggest that the association between HLA polymorphism and risk of ICC might be influenced by the distribution of HPV-16 variants.

Forest structure and live aboveground biomass variation along an elevational gradient of tropical Atlantic moist forest (Brazil)

Live aboveground biomass (AGB) is an important source of uncertainty in the carbon balance from the tropical regions in part due scarcity of reliable estimates of live AGB and its variation across landscapes and forest types. Studies of forest structure and biomass stocks of Neotropical forests are biased toward Amazonian and Central American sites. In particular, standardized estimates of aboveground biomass stocks for the Brazilian Atlantic forest are rarely available. Notwithstanding the role of environmental variables that control the distribution and abundance of biomass in tropical lowland forests has been the subject of considerable research, the effect of short, steep elevational gradients on tropical forest structure and carbon dynamics is not well known. In order to evaluate forest structure and live AGB variation along an elevational gradient (0-1100 m a.s.l.) of coastal Atlantic Forest in SE Brazil, we carried out a standard census of woody stems >= 4.8 cm dbh in 13 1-ha permanent plots established on four different sites in 2006-2007. Live AGB ranged from 166.3 Mg ha(-1) (bootstrapped 95% CI: 1444,187.0) to 283.2 Mg ha(-1) (bootstrapped 95% CI: 253.0,325.2) and increased with elevation. We found that local-scale topographic variation associated with elevation influences the distribution of trees >50 cm dbh and total live AGB. Across all elevations, we found more stems (64-75%) with limited crown illumination but the largest proportion of the live AGB (68-85%) was stored in stems with highly illuminated or fully exposed crowns. Topography, disturbance and associated changes in light and nutrient supply probably control biomass distribution along this short but representative elevational gradient. Our findings also showed that intact Atlantic forest sites stored substantial amounts of carbon aboveground. The live tree AGB of the stands was found to be lower than Central Amazonian forests, but within the range of Neotropical forests, in particular when compared to Central American forests. Our comparative data suggests that differences in live tree AGB among Neotropical forests are probably related to the heterogeneous distribution of large and medium-sized diameter trees within forests and how the live biomass is partitioned among those size classes, in accordance with general trends found by previous studies. In addition, the elevational variation in live AGB stocks suggests a large spatial variability over coastal Atlantic forests in Brazil, clearly indicating that it is important to consider regional differences in biomass stocks for evaluating the role of this threatened tropical biome in the global carbon cycle. (C) 2010 Elsevier B.V. All rights reserved.

Increasing trends of sleep complaints in the city of Sao Paulo, Brazil

Objective: The aim of this study was to compare the prevalence of sleep habits and complaints and to estimate the secular trends through three population-based surveys carried out in 1987, 1995, and 2007 in the general adult population of the city of Sao Paulo, Brazil. Methods: Surveys were performed using the same three-stage cluster-sampling technique in three consecutive decades to obtain representative samples of the inhabitants of Sao Paulo with respect to gender, age (20-80 years), and socio-economic status. Sample sizes were 1000 volunteers in 1987 and 1995 surveys and 1101 in a 2007 survey. In each survey, the UNIFESP Sleep Questionnaire was administered face-to-face in each household selected. Results: For 1987, 1995, and 2007, respectively, difficulty initiating sleep (weighted frequency %; 95% CI) [(13.9; 11.9-16.2), (19.15; 16.8-21.6), and (25.0; 22.5-27.8)], difficulty maintaining sleep [(15.8; 13.7-18.2), (27.6; 24.9-30.4), and (36.5; 33.5-39.5)], and early morning awakening [(10.6; 8.8-12.7), (14.2; 12.2-16.5), and (26.7; 24-29.6)] increased in the general population over time, mostly in women. Habitual snoring was the most commonly reported complaint across decades and was more prevalent in men. There was no statistically significant difference in snoring complaints between 1987 (21.5; 19.1-24.2) and 1995 (19.0; 16.7-21.6), but a significant increase was noted in 2007 (41.7; 38.6-44.8). Nightmares, bruxism, leg cramps, and somnambulism complaints were significantly higher in 2007 compared to 1987 and 1995. All were more frequent in women. Conclusions: This is the first study comparing sleep complaints in probabilistic population-based samples from the same metropolitan area, using the same methodology across three consecutive decades. Clear trends of increasing sleep complaints were observed, which increased faster between 1995 and 2007 than from 1987 to 1995. These secular trends should be considered a relevant public health issue and support the need for development of health care and educational strategies to supply the population`s increased need for information on sleep disorders and their consequences. (C) 2010 Elsevier B.V. All rights reserved.

Predictive Validity of Waterlow Scale for Pressure Ulcer Development Risk in Hospitalized Patients

AIM: We sought to evaluate the predictive validity of the Waterlow Scale in hospitalized patients. SUBJECTS AND SETTING: The study was conducted at a general private hospital with 220 beds and a mean time of hospitalization of 7.4 days and a mean occupation rate of approximately 80%. Adult patients with a Braden Scale score of 18 or less and a Waterlow Scale score of 16 or more were studied. The sample consisted of 98 patients with a mean age of 71.1 +/- 15.5 years. METHODS: Skin assessment and scoring by using the Waterlow and Braden scales were completed on alternate days. Patients were examined at least 3 times to be considered for analysis. The data were submitted to sensitivity and specificity analysis by using receiver operating characteristic (ROC) curves and positive (+LR) and negative (-LR) likelihood ratios. RESULTS: The cutoff scores were 17, 20, and 20 in the first, second, and third assessment, respectively. Sensitivity was 71.4%, 85.7%, and 85.7% and specificity was 67.0%, 40.7%, and 32.9%, respectively. Analysis of the area under the ROC curve revealed good accuracy (0.64, 95% confidence interval [CI]: 0.35-0.93) only for the cutoff score 17 in the first assessment. The results also showed probabilities of 14%, 10%, and 9% for the development of pressure ulcer when the test results were positive (+LR) and of 3% (-LR) when the test results were negative for the cutoff scores in the first, second, and third assessment, respectively. CONCLUSION: The Waterlow Scale achieved good predictive validity in predicting pressure ulcer in hospitalized patients when a cutoff score of 17 was used in the first assessment.

Risk factors for neonatal transfers from the Sapopemba free-standing birth centre to a hospital in Sao Paulo, Brazil

Objective: to identify risk factors associated with neonatal transfers from a free-standing birth centre to a hospital. Design: epidemiological case-control study. Setting: midwifery-led free-standing birth centre in Sao Paulo, Brazil. Participants: 96 newborns were selected from 2840 births between September 1998 and August 2005. Cases were defined as all new borns transferred from the birth centre to a hospital (n = 32), and controls were defined as new borns delivered at the same birth centre, during the same time period, and who had not been transferred to a hospital (n = 64). Measurements and findings: data were collected from medical records available at the birth centre. Univariate and multivariate analyses were performed using logistic regression. The multivariate analysis included outcomes with p<0.25, specifically: smoking during pregnancy, prenatal care appointments, labour complications, weight in relation to gestational age, and one-minute Apgar score. Of the foregoing outcomes, those that remained in the full regression model as a risk factor associated with neonatal transfer were: smoking during pregnancy [p = 0.009, odds ratio (OR) = 4.1,95% confidence interval (CI) 1.03-16.33], labour complications (p<0.001, OR = 5.5, 95% CI 1.06-28.26) and one-minute Apgar score <= 7 (p<0.001, OR = 7.8,95% CI 1.62-37.03). Key conclusions and implications for practice: smoking during pregnancy, labour complications and one-minute Apgar score <= 7 were confirmed as risk factors for neonatal transfer from the birth centre to a hospital. The identified risk factors can help to improve institutional protocols and formulate hypotheses for other studies. (C) 2009 Elsevier Ltd. All rights reserved.

Effectiveness of local anaesthetics with and without vasoconstrictors for perineal repair during spontaneous delivery: Double-blind randomised controlled trial

Objective: to investigate the use of local anaesthetics, in the presence or absence of vasoconstrictors, for perineal repair during spontaneous delivery. Design: double-blind, randomised-controlled trial. Setting: a birth centre, in the city of Sao Paulo, Brazil. Participants: from June to December 2004, a total of 96 women were allocated into three groups (first-degree perineal lacerations, second-degree perineal lacerations or episiotomy), and treated with local anaesthesia (1% lidocaine or 1% lidocaine with epinephrine) (n = 16 per treatment per group). Interventions: an initial local infiltration of the anaesthetic solution was given so that episiotomy could be carried out (5 ml) and to suture spontaneous lacerations (1 ml), followed by repeated doses (1 ml) until pain was completely inhibited. Measurements and findings: the main outcome measurement was the volume of anaesthetic used during episiotomy and perineal suture. Our data suggest that the concomitant use of the vasoconstrictor resulted in a significantly lower average volume used in the treatment of first-degree (1 ml, 95% confidence interval (0) 0.4-1.6) and second-degree (3.7 ml, 95% CI 1.6-5.8) lacerations (p = 0.002 and 0.001, respectively). A 0.3 ml (95% CI 1.5-2.1) average decrease in anaesthetic volume was observed with episiotomy (p = 0.724). The maximum volume of anaesthetic used with and without vasoconstrictor was 1-2 ml in 95% and 3-4 ml in 50% of first-degree lacerations, respectively, and 1-6 ml in 88% and 7-15 ml in 81% of second-degree lacerations, respectively. For episiotomy, the maximum dose was 15 ml, regardless of anaesthetic solution used. Key conclusions: our data confirm the hypothesis that the use of anaesthetics in conjunction with vasoconstrictors is more effective than anaesthetics alone in the repair of perineal lacerations, but not for episiotomy. (C) 2007 Elsevier Ltd. All rights reserved.

Effects of Varenicline in Adult Smokers: A Multinational, 24-Week, Randomized, Double-Blind, Placebo-Controlled Study

Background: Prevalence rates of smoking are rising in developing countries. Previous trials evaluating the efficacy and tolerability of the smoking-cessation medication varenicline have used largely participants of Caucasian origin. Objective: This study was conducted to evaluate the efficacy and tolerability of varenicline in populations of participants from Latin America, Africa, and the Middle East to investigate potential differences in the therapeutic response to varenicline. Methods: This multinational, randomized, double-blind, placebo-controlled trial was conducted at 42 centers in 11 countries (Latin America: Brazil, Colombia, Costa Rica, Mexico, and Venezuela; Africa: Egypt and South Africa; Middle East: Jordan, Lebanon, Saudi Arabia, and the United Arab Emirates). Participants were male and female smokers aged 18 to 75 years who were motivated to stop smoking; smoked >= 10 cigarettes/d, with no cumulative period of abstinence >3 months in the previous year; and who had no serious or unstable disease within the previous 6 months. Subjects were randomized in a 2:1 ratio to receive varenicline 1 mg or placebo, BID for 12 weeks, with a 12-week nontreatment follow-up. Brief smoking-cessation counseling was provided. The main outcome measures were carbon monoxide confirmed continuous abstinence rate (CAR) at weeks 9 to 12 and weeks 9 to 24. Adverse events (AEs) were recorded for tolerability assessment. Results: Overall, 588 subjects (varenicline, 390; placebo, 198) were randomized and treated. The mean (SD) ages of subjects in the varenicline and placebo groups were 43.1 (10.8) and 43.9 (10.8) years, respectively; 57.7% and 65.7% were male; and the mean (SD) weights were 75.0 (16.0) and 76.7 (16.3) kg (range, 40.0-130.0 and 45.6-126.0 kg). CAR at weeks 9 to 12 was significantly higher with varenicline than with placebo (53.59% vs 18.69%; odds ratio [OR] = 5.76; 95% CI, 3.74-8.88; P < 0.0001), and this rate was maintained during weeks 9 to 24 (39.74% vs 13.13%; OR = 4.78; 95% CI, 2.97-7.68; P < 0.0001). Nausea, headache, and insomnia were the most commonly reported AEs with varenicline and were reported numerically more frequently in the varenicline group compared with the placebo group. Serious AEs (SAEs) were reported in 2.8% of varenicline recipients compared with 1.0% in the placebo group, with 6 subjects reporting psychiatric SAEs compared with none in the placebo group. Conclusion: Based on these data, varenicline was apparently efficacious and generally well tolerated as a smoking-cessation aid in smokers from selected sites in Latin America, Africa, and the Middle East. ClinicalTrials. gov identifier: NCT00594204. (Clin Ther. 2011;33:465-477) (C) 2011 Published by Elsevier HS Journals, Inc.

Comparison between constant and decreasing rest intervals: influence on maximal strength and hypertrophy

de Souza Jr, TP, Fleck, SJ, Simao, R, Dubas, JP, Pereira, B, de Brito Pacheco, EM, da Silva, AC, and de Oliveira, PR. Comparison between constant and decreasing rest intervals: influence on maximal strength and hypertrophy. J Strength Cond Res 24(7): 1843-1850, 2010-Most resistance training programs use constant rest period lengths between sets and exercises, but some programs use decreasing rest period lengths as training progresses. The aim of this study was to compare the effect on strength and hypertrophy of 8 weeks of resistance training using constant rest intervals (CIs) and decreasing rest intervals (DIs) between sets and exercises. Twenty young men recreationally trained in strength training were randomly assigned to either a CI or DI training group. During the first 2 weeks of training, 3 sets of 10-12 repetition maximum (RM) with 2-minute rest intervals between sets and exercises were performed by both groups. During the next 6 weeks of training, the CI group trained using 2 minutes between sets and exercises (4 sets of 8-10RM), and the DI group trained with DIs (2 minutes decreasing to 30 seconds) as the 6 weeks of training progressed (4 sets of 8-10RM). Total training volume of the bench press and squat were significantly lower for the DI compared to the CI group (bench press 9.4%, squat 13.9%) and weekly training volume of these same exercises was lower in the DI group from weeks 6 to 8 of training. Strength (1RM) in the bench press and squat, knee extensor and flexor isokinetic measures of peak torque, and muscle cross-sectional area (CSA) using magnetic resonance imaging were assessed pretraining and posttraining. No significant differences (p <= 0.05) were shown between the CI and DI training protocols for CSA (arm 13.8 vs. 14.5%, thigh 16.6 vs. 16.3%), 1RM (bench press 28 vs. 37%, squat 34 vs. 34%), and isokinetic peak torque. In conclusion, the results indicate that a training protocol with DI is just as effective as a CI protocol over short training periods (6 weeks) for increasing maximal strength and muscle CSA; thus, either type of program can be used over a short training period to cause strength and hypertrophy.

Relationship between installation torque and uplift capacity of deep helical piles in sand

Le facteur empirique de correlation du torque K(T), qui represente la capacite de soulevement du torque d`installation de pieux helicoidaux, est generalement utilise comme instrument de controle de la qualite sur le terrain pour ce type de fondations. Dans cet article, une relation theorique entre la capacite de soulevement et le torque d`installation de pieux helicoidaux places profondement dans du sable est presentee. Un programme experimental, qui comprend des essais centrifuge et de cisaillement direct a l`interface, a ete effectue dans le but de valider cette relation theorique. Les resultats experimentaux ont ete compares aux resultats predits par l`approche suggeree, et les resultats montrent une bonne concordance. Puisque le modele developpe depend de l`angle de friction residuel a l`interface delta(r) entre la surface de l`helice du pieu et le sable, les resultats de delta(r) obtenus a partir de differents echantillons de sable sont presentes afin d`etre utilises lors de l`application sur le terrain de la relation theorique proposee. De plus, les valeurs de K(T) obtenues dans ces travaux ont ete comparees a celles reportees dans la litterature; celles-ci ayant ete obtenues lors d`essais sur le terrain et en laboratoire sur des pieux helicoidaux dans le sable. Cette analyse a permis de demontrer que les valeurs mesurees de K(T) diminuent lorsque la dimension des pieux augmente, ainsi qu`avec une augmentation de l`angle de friction du sable, dans la plupart des cas. Ces derniers resultats ont aussi ete demontres avec le modele presente.

Analysis of the emissions of volatile organic compounds from the compression ignition engine fueled by diesel-biodiesel blend and diesel oil using gas chromatography

This paper describes the procedures of the analysis Of Pollutant gases, as volatile organic compounds (benzene, toluene, ethylbenzene, o-xylene, m-xylene and p-xylene) emitted by engines, using high-resolution gas chromatography (HRGC). In a broad sense, CI engine burning diesel was compared with B10 and a drastic reduction was observed in the emissions of the aromatic compounds by using B10. Especially for benzene, the reduction of concentrations occurs on the level of about 19.5%. Although a concentration value below 1 mu g ml(-1) has been obtained, this reduction is extremely significant since benzene is a carcinogenic compound. (c) 2008 Elsevier Ltd. All rights reserved.