Estimating subsoil resistance to nitrate leaching from easily measurable pedological properties

Leaching of nitrate (NO3-) can increase the groundwater concentration of this anion and reduce the agronomical effectiveness of nitrogen fertilizers. The main soil property inversely related to NO3- leaching is the anion exchange capacity (AEC), whose determination is however too time-consuming for being carried out in soil testing laboratories. For this reason, this study evaluated if more easily measurable soil properties could be used to estimate the resistance of subsoils to NO3- leaching. Samples from the subsurface layer (20-40 cm) of 24 representative soils of São Paulo State were characterized for particle-size distribution and for chemical and electrochemical properties. The subsoil content of adsorbed NO3- was calculated from the difference between the NO3- contents extracted with 1 mol L-1 KCl and with water; furthermore, NO3- leaching was studied in miscible displacement experiments. The results of both adsorption and leaching experiments were consistent with the well-known role exerted by AEC on the nitrate behavior in weathered soils. Multiple regression analysis indicated that in subsoils with (i) low values of remaining phosphorus (Prem), (ii) low soil pH values measured in water (pH H2O), and (iii) high pH values measured in 1 moL L-1 KCl (pH KCl), the amounts of surface positive charges tend to be greater. For this reason, NO3- leaching tends to be slower in these subsoils, even under saturated flow condition.

Muscular development and physical activity as major determinants of femoral bone mass acquisition during growth

[EN] OBJECTIVES: To investigate to what extent bone mass accrual is determined by physical activity and changes in lean, fat, and total body mass during growth. METHODS: Twenty six physically active and 16 age matched control boys were followed up for three years. All subjects were prepubertal at the start of the survey (mean (SEM) age 9.4 (0.3) years). The weekly physical activity of the active boys included compulsory physical education sessions (80-90 minutes a week), three hours a week of extracurricular sports participation, and occasional sports competitions at weekends. The physical activity of the control group was limited to the compulsory physical education curriculum. Bone mineral content (BMC) and areal density (BMD), lean mass, and fat mass were measured by dual energy x ray absorptiometry. RESULTS: The effect of sports participation on femoral bone mass accrual was remarkable. Femoral BMC and BMD increased twice as much in the active group as in the controls over the three year period (p < 0.05). The greatest correlation was found between the increment in femoral bone mass and the increment in lean mass (BMC r = 0.67 and BMD r = 0.69, both p < 0.001). Multiple regression analysis revealed enhancement in lean mass as the best predictor of the increment in femoral bone BMC (R = 0.65) and BMD (R = 0.69). CONCLUSIONS: Long term sports participation during early adolescence results in greater accrual of bone mass. Enhancement of lean mass seems to be the best predictor of this bone mass accumulation. However, for a given muscle mass, a greater level of physical activity is associated with greater bone mass and density in peripubertal boys.

Relationships between running economy and mechanics in middle-distance runners

Running economy (RE), i.e. the oxygen consumption at a given submaximal speed, is an important determinant of endurance running performance. So far, investigators have widely attempted to individuate the factors affecting RE in competitive athletes, focusing mainly on the relationships between RE and running biomechanics. However, the current results are inconsistent and a clear mechanical profile of an economic runner has not been yet established. The present work aimed to better understand how the running technique influences RE in sub-elite middle-distance runners by investigating the biomechanical parameters acting on RE and the underlying mechanisms. Special emphasis was given to accounting for intra-individual variability in RE at different speeds and to assessing track running rather than treadmill running. In Study One, a factor analysis was used to reduce the 30 considered mechanical parameters to few global descriptors of the running mechanics. Then, a biomechanical comparison between economic and non economic runners and a multiple regression analysis (with RE as criterion variable and mechanical indices as independent variables) were performed. It was found that a better RE was associated to higher knee and ankle flexion in the support phase, and that the combination of seven individuated mechanical measures explains ∼72% of the variability in RE. In Study Two, a mathematical model predicting RE a priori from the rate of force production, originally developed and used in the field of comparative biology, was adapted and tested in competitive athletes. The model showed a very good fit (R2=0.86). In conclusion, the results of this dissertation suggest that the very complex interrelationships among the mechanical parameters affecting RE may be successfully dealt with through multivariate statistical analyses and the application of theoretical mathematical models. Thanks to these results, coaches are provided with useful tools to assess the biomechanical profile of their athletes. Thus, individual weaknesses in the running technique may be identified and removed, with the ultimate goal to improve RE.

Studio neuroradiologico (morfologico e funzionale) nei pazienti con Epilessia Frontale Notturna

L'epilessia frontale notturna (EFN) è caratterizzata da crisi motorie che insorgono durante il sonno. Scopo del progetto è studiare le cause fisiopatologiche e morfo-funzionali che sottendono ai fenomeni motori nei pazienti con EFN e identificare alterazioni strutturali e/o metaboliche mediante tecniche avanzate di Risonanza Magnetica (RM). Abbiamo raccolto una casistica di pazienti con EFN afferenti al Centro Epilessia e dei Disturbi del Sonno del Dipartimento di Scienze Neurologiche, Università di Bologna. Ad ogni paziente è stato associato un controllo sano di età (± 5 anni) e sesso corrispondente. Tutti sono stati studiati mediante tecniche avanzate di RM comprendenti Spettroscopia del protone (1H-MRS), Tensore di diffusione ed imaging 3D ad alta risoluzione per analisi morfometriche. In particolare, la 1H-MRS è stata effettuata su due volumi di interesse localizzati nei talami e nel giro del cingolo anteriore. Sono stati inclusi nell’analisi finale 19 pazienti (7 M), età media 34 anni (range 19-50) e 14 controlli (6 M) età media 30 anni (range 19-40). A livello del cingolo anteriore il rapporto della concentrazione di N-Acetil-Aspartato rispetto alla Creatina (NAA/Cr) è risultato significativamente ridotto nei pazienti rispetto ai controlli (p=0,021). Relativamente all’analisi di correlazione, l'analisi tramite modelli di regressione multipla ha evidenziato che il rapporto NAA/Cr nel cingolo anteriore nei pazienti correlava con la frequenza delle crisi (p=0,048), essendo minore nei pazienti con crisi plurisettimanali/plurigiornaliere. Per interpretare il dato ottenuto è possibile solo fare delle ipotesi. L’NAA è un marker di integrità, densità e funzionalità neuronale. E’ possibile che alla base della EFN ci siano alterazioni metaboliche tessutali in precise strutture come il giro del cingolo anteriore. Questo apre nuove possibilità sull’utilizzo di strumenti di indagine basati sull’analisi di biosegnali, per caratterizzare aree coinvolte nella genesi della EFN ancora largamente sconosciute e chiarire ulteriormente l’eziologia di questo tipo di epilessia.

Politische Ökonomie des Wirtschaftswachstums in defekten Demokratien : eine empirische Untersuchung im Vergleich zu Demokratien und Autokratien

Die Arbeit untersucht das Wirtschaftswachstum von defekten Demokratien im Vergleich zu Autokatien und liberalen Demokratien mittels multiple Regressionsanylsen. Theoretischer Hintergrund sind die Arbeiten Mancur Olsons und Bruce Bueno de Mesquitas. Die Messung defekter Demokratien wird mittels dem Freedom House Freedom in the World Index und dem Electoral Democracy Index unternommen. Ergebnis der Analyse ist, dass defekte Demokratien rund ein Prozentpunkt schneller wachsen als liebrale Demokratien. Im Vergleich zu Autokratien besteht kein signifikanter Unterschied.

Effect of pulsatility on the mathematical modeling of rotary blood pumps

In this study, the effect of time derivatives of flow rate and rotational speed was investigated on the mathematical modeling of a rotary blood pump (RBP). The basic model estimates the pressure head of the pump as a dependent variable using measured flow and speed as predictive variables. Performance of the model was evaluated by adding time derivative terms for flow and speed. First, to create a realistic working condition, the Levitronix CentriMag RBP was implanted in a sheep. All parameters from the model were physically measured and digitally acquired over a wide range of conditions, including pulsatile speed. Second, a statistical analysis of the different variables (flow, speed, and their time derivatives) based on multiple regression analysis was performed to determine the significant variables for pressure head estimation. Finally, different mathematical models were used to show the effect of time derivative terms on the performance of the models. In order to evaluate how well the estimated pressure head using different models fits the measured pressure head, root mean square error and correlation coefficient were used. The results indicate that inclusion of time derivatives of flow and speed can improve model accuracy, but only minimally.

Vitrectomy for juvenile uveitis: prognostic factors for the long-term functional outcome

PURPOSE: This study evaluated the long-term effect of pars plana vitrectomy (PPV) in children and adolescents with chronic uveitis on visual function, anatomical outcome, and the requirement of systemic treatment. Further, predictive preoperative factors associated with a beneficial visual outcome were assessed. METHODS: Retrospective review of 29 eyes of 23 consecutive paediatric and juvenile patients below 20 years of age with chronic uveitis who underwent a PPV for visually significant opacities in 25 eyes, vitreous haemorrhage in three eyes, and retinal detachment in one eye. The clinical diagnosis was chronic intermediate uveitis in 22 eyes and retinal vasculitis of different origin in seven eyes. RESULTS: LogMAR visual acuity improved from an average of 0.91 to 0.33 (P<0.001). Cystoid macular oedema (CME) was significantly reduced in eight of 10 eyes postoperatively (P=0.021). In the multiple regression analysis, a low preoperative logMAR visual acuity and the presence of a CME had a negative influence on the final logMAR visual acuity. Furthermore, the appearance of chronic uveitis relapses was significantly reduced from 15 eyes before to seven eyes after surgery (P=0.042). CONCLUSIONS: PPV has a beneficial effect on the course and the complications of chronic uveitis in paediatric and juvenile patients with respect to the anatomical and visual outcome. Preoperative logMAR visual acuity and clinically significant CME were the most accurate predictors for the functional outcome.

Comparison of intraarterial and intravenous thrombolysis for ischemic stroke with hyperdense middle cerebral artery sign

BACKGROUND AND PURPOSE: It is unclear whether intraarterial (IAT) or intravenous (IVT) thrombolysis is more effective for ischemic stroke with hyperdense middle cerebral artery sign (HMCAS) on computed tomography (CT). The aim of this study was to compare IAT and IVT in stroke patients with HMCAS. METHODS: Comparison of data from 2 stroke units with similar management of stroke associated with HMCAS, except that 1 unit performed IAT with urokinase and the other IVT with plasminogen activator. Time to treatment was up to 6 hours for IAT and up to 3 hours for IVT. Outcome was measured by mortality and the modified Rankin Scale (mRS), dichotomized at 3 months into favorable (mRS 0 to 2) and unfavorable (mRS 3 to 6). RESULTS: One hundred twelve patients exhibited a HMCAS, 55 of 268 patients treated with IAT and 57 of 249 patients who underwent IVT. Stroke severity at baseline and patient age were similar in both groups. Mean time to treatment was longer in the IAT group (244+/-63 minutes) than in the IVT group (156+/-21 minutes; P=0.0001). However, favorable outcome was more frequent after IAT (n=29, 53%) than after IVT (n=13, 23%; P=0.001), and mortality was lower after IAT (n=4, 7%) than after IVT (n=13, 23%; P=0.022). After multiple regression analysis IAT was associated with a more favorable outcome than IVT (P=0.003) but similar mortality (P=0.192). CONCLUSIONS: In this observational study intraarterial thrombolysis was more beneficial than IVT in the specific group of stroke patients presenting with HMCAS on CT, even though IAT was started later. Our results indicate that a randomized trial comparing both thrombolytic treatments in patients with middle cerebral artery occlusion is warranted.

Intravascular US-guided direct intrahepatic portocaval shunt with an expanded polytetrafluoroethylene-covered stent-graft

PURPOSE: To retrospectively evaluate the midterm patency rate of the nitinol (Viatorr, W.L. Gore and Associates, Flagstaff, Ariz) stent-graft for direct intrahepatic portacaval shunt (DIPS) creation. MATERIALS AND METHODS: Institutional Review Board approval for this retrospective HIPAA-compliant study was obtained with waiver of informed consent. DIPS was created in 18 men and one woman (median age, 54 years; range, 45-65 years) by using nitinol polytetrafluoroethylene (PTFE)-covered stent-grafts. The primary indications were intractable ascites (n = 14), acute variceal bleeding (n = 3), and hydrothorax (n = 2). Follow-up included Doppler ultrasonography at 1, 6, and 12 months and venography with manometry at 6-month intervals after the procedure. Shunt patency and cumulative survival were evaluated by using the Kaplan-Meier method and survival curves were plotted. Differences in mean portosystemic gradients (PSGs) were evaluated by using the Student t test. Multiple regression analysis for survival and DIPS patency were performed for the following parameters: Child-Pugh class, model of end-stage liver disease score, pre- and post-DIPS PSGs, pre-DIPS liver function tests, and pre-DIPS creatinine levels. RESULTS: DIPS creation was successful in all patients. Effective portal decompression and free antegrade shunt flow was achieved in all patients. Intraperitoneal bleeding occurred in one patient during the procedure and was controlled during the same procedure by placing a second nitinol stent-graft. The primary patency rate was 100% at all times during the follow-up period (range, 2 days to 30 months; mean, 256 days; median, 160 days). Flow restrictors were deployed in two (11%) of 19 patients. The 1-year mortality rate was 37% (seven of 19). CONCLUSION: Patency after DIPS creation with the nitinol PTFE-covered stent-graft was superior to that after TIPS with the nitinol stent-graft.

EVALUATION OF INTELLIGENT COMPACTION CONTROL IN THE M-189 RECONSTRUCTION PROJECT AT IRON RIVER, MICHIGAN

This research evaluated an Intelligent Compaction (IC) unit on the M-189 highway reconstruction project at Iron River, Michigan. The results from the IC unit were compared to several traditional compaction measurement devices including Nuclear Density Gauge (NDG), Geogauge, Light Weight Deflectometer (LWD), Dynamic Cone Penetrometer (DCP), and Modified Clegg Hammer (MCH). The research collected point measurements data on a test section in which 30 test locations on the final Class II sand base layer and the 22A gravel layer. These point measurements were compared with the IC measurements (ICMVs) on a point-to-point basis through a linear regression analysis. Poor correlations were obtained among different measurements points using simple regression analysis. When comparing the ICMV to the compaction measurements points. Factors attributing to the weak correlation include soil heterogeneity, variation in IC roller operation parameters, in-place moisture content, the narrow range of the compaction devices measurement ranges and support conditions of the support layers. After incorporating some of the affecting factors into a multiple regression analysis, the strength of correlation significantly improved, especially on the stiffer gravel layer. Measurements were also studied from an overall distribution perspective in terms of average, measurement range, standard deviation, and coefficient of variance. Based on data analysis, on-site project observation and literature review, conclusions were made on how IC performed in regards to compaction control on the M-189 reconstruction project.

Connective tissue growth factor, steatosis and fibrosis in patients with chronic hepatitis C

BACKGROUND/AIM: Both steatosis and insulin resistance have been linked to accelerated fibrosis in chronic hepatitis C. Connective tissue growth factor (CTGF) plays a major role in extracellular matrix production in fibrotic disorders including cirrhosis, and its expression is stimulated in vitro by insulin and glucose. We hypothesized that CTGF may link steatosis, insulin resistance and fibrosis. METHODS: We included 153 chronic hepatitis C patients enrolled in the Swiss Hepatitis C Cohort Study and for whom a liver biopsy and plasma samples were available. CTGF expression was assessed quantitatively by immunohistochemistry. In 94 patients (57 with genotypes non-3), plasma levels of glucose, insulin and leptin were also measured. CTGF synthesis was investigated by immunoblotting on LX-2 stellate cells. RESULTS: Connective tissue growth factor expression was higher in patients with steatosis (P=0.039) and in patients with fibrosis (P=0.008) than those without these features. CTGF levels were neither associated with insulinaemia or with glycaemia, nor with inflammation. By multiple regression analysis, CTGF levels were independently associated with steatosis, a past history of alcohol abuse, plasma leptin and HCV RNA levels; when only patients with genotypes non-3 were considered, CTGF levels were independently associated with a past history of alcohol abuse, plasma leptin levels and steatosis. Leptin stimulated CTGF synthesis in LX-2 cells. CONCLUSIONS: In patients with chronic hepatitis C and steatosis, CTGF may promote fibrosis independently of inflammation. CTGF may link steatosis and fibrosis via increased leptin levels.

Effects of gender and dementia severity on Alzheimer's disease caregivers' sleep and biomarkers of coagulation and inflammation

BACKGROUND: Being a caregiver for a spouse with Alzheimer's disease is associated with increased risk for cardiovascular illness, particularly for males. This study examined the effects of caregiver gender and severity of the spouse's dementia on sleep, coagulation, and inflammation in the caregiver. METHODS: Eighty-one male and female spousal caregivers and 41 non-caregivers participated (mean age of all participants 70.2 years). Full-night polysomnography (PSG) was recorded in each participants home. Severity of the Alzheimer's disease patient's dementia was determined by the Clinical Dementia Rating (CDR) scale. The Role Overload scale was completed as an assessment of caregiving stress. Blood was drawn to assess circulating levels of D-dimer and Interleukin-6 (IL-6). RESULTS: Male caregivers who were caring for a spouse with moderate to severe dementia spent significantly more time awake after sleep onset than female caregivers caring for spouses with moderate to severe dementia (p=.011), who spent a similar amount of time awake after sleep onset to caregivers of low dementia spouses and to non-caregivers. Similarly, male caregivers caring for spouses with worse dementia had significantly higher circulating levels of D-dimer (p=.034) than females caring for spouses with worse dementia. In multiple regression analysis (adjusted R(2)=.270, p<.001), elevated D-dimer levels were predicted by a combination of the CDR rating of the patient (p=.047) as well as greater time awake after sleep onset (p=.046). DISCUSSION: The findings suggest that males caring for spouses with more severe dementia experience more disturbed sleep and have greater coagulation, the latter being associated with the disturbed sleep. These findings may provide insight into why male caregivers of spouses with Alzheimer's disease are at increased risk for illness, particularly cardiovascular disease.

Predictors of inflammation in response to anthracycline-based chemotherapy for breast cancer

Although chemotherapy for breast cancer can increase inflammation, few studies have examined predictors of this phenomenon. This study examined potential contributions of demographics, disease characteristics, and treatment regimens to markers of inflammation in response to chemotherapy for breast cancer. Thirty-five women with stage I-III-A breast cancer (mean age 50 years) were studied prior to cycle 1 and prior to cycle 4 of anthracycline-based chemotherapy. Circulating levels of inflammatory markers with high relevance to breast cancer were examined, including C-reactive protein (CRP), tumor necrosis factor-alpha (TNF-alpha), Interleukin-1 receptor antagonist (IL1-RA), vascular endothelial growth factor (VEGF), soluble intercellular adhesion molecule-1 (sICAM-1), Interleukin- (IL-6), soluble P-selectin (sP-selectin), and von Willebrand factor (vWf). Chemotherapy was associated with elevations in VEGF (p < or = 0.01), sICAM-1 (p < or = 0.01), sP-selectin (p < or = 0.02) and vWf (p < or = 0.05). Multiple regression analysis controlling for age and body mass index (BMI) showed that higher post-chemotherapy levels of inflammation were consistently related to higher pre-chemotherapy levels of inflammation (ps < or =0.05) as well as to certain disease characteristics. Post-chemotherapy IL-6 levels were higher in patients who had larger tumors (p < or = 0.05) while post-chemotherapy VEGF levels were higher in patients who had smaller tumors (p < or = 0.05). Post-chemotherapy sP-selectin levels were highest in women who had received epirubicin, cytoxan, 5-fluorouracil chemotherapy (p < or = 0.01). These findings indicate that chemotherapy treatment can be associated with elevations in certain markers of inflammation, particularly markers of endothelial and platelet activation. Inflammation in response to chemotherapy is most significantly related to inflammation that existed prior to chemotherapy but also potentially to treatment regimen and to certain disease characteristics.

Benchmarking with Spine Tango: potentials and pitfalls

The newly released online statistics function of Spine Tango allows comparison of own data against the aggregated results of the data pool that all other participants generate. This comparison can be considered a very simple way of benchmarking, which means that the quality of what one organization does is compared with other similar organizations. The goal is to make changes towards better practice if benchmarking shows inferior results compared with the pool. There are, however, pitfalls in this simplified way of comparing data that can result in confounding. This means that important influential factors can make results appear better or worse than they are in reality and these factors can only be identified and neutralized in a multiple regression analysis performed by a statistical expert. Comparing input variables, confounding is less of a problem than comparing outcome variables. Therefore, the potentials and limitations of automated online comparisons need to be considered when interpreting the results of the benchmarking procedure.

A prediction model for personal radio frequency electromagnetic field exposure

Radio frequency electromagnetic fields (RF-EMF) in our daily life are caused by numerous sources such as fixed site transmitters (e.g. mobile phone base stations) or indoor devices (e.g. cordless phones). The objective of this study was to develop a prediction model which can be used to predict mean RF-EMF exposure from different sources for a large study population in epidemiological research. We collected personal RF-EMF exposure measurements of 166 volunteers from Basel, Switzerland, by means of portable exposure meters, which were carried during one week. For a validation study we repeated exposure measurements of 31 study participants 21 weeks after the measurements of the first week on average. These second measurements were not used for the model development. We used two data sources as exposure predictors: 1) a questionnaire on potentially exposure relevant characteristics and behaviors and 2) modeled RF-EMF from fixed site transmitters (mobile phone base stations, broadcast transmitters) at the participants' place of residence using a geospatial propagation model. Relevant exposure predictors, which were identified by means of multiple regression analysis, were the modeled RF-EMF at the participants' home from the propagation model, housing characteristics, ownership of communication devices (wireless LAN, mobile and cordless phones) and behavioral aspects such as amount of time spent in public transports. The proportion of variance explained (R2) by the final model was 0.52. The analysis of the agreement between calculated and measured RF-EMF showed a sensitivity of 0.56 and a specificity of 0.95 (cut-off: 90th percentile). In the validation study, the sensitivity and specificity of the model were 0.67 and 0.96, respectively. We could demonstrate that it is feasible to model personal RF-EMF exposure. Most importantly, our validation study suggests that the model can be used to assess average exposure over several months.