Microclimate modification by tree windbreaks in Florida farms

Paper presented at the 11th North American Agroforesty Conference, which was held May 31-June 3, 2009 in Columbia, Missouri.In Gold, M.A. and M.M. Hall, eds. Agroforestry Comes of Age: Putting Science into Practice. Proceedings, 11th North American Agroforestry Conference, Columbia, Mo., May 31-June 3, 2009.Florida citrus and vegetable crops generate billions in revenue every year. However, winds, freezes, hurricanes, and citrus canker (Xanthomonas campestris) impact production. Windbreaks located perpendicular to the prevailing wind can reduce soil erosion and increase irrigation efficiency and farm production mostly by simply modifying microclimate. Windbreaks can also control the spread of pathogens such as citrus canker. To study how tree windbreaks modify microclimate in southern Florida, weather stations were established in 2008 along transects behind a 1-row eastern redcedar (Juniperus virginiana) windbreak at the Southwest Florida Research and Education Center (SWFREC/University of Florida) at Immokalee, and a 1-row cadaghi (Corymbia torelliana) windbreak at C&B Farms, Clewiston, to assess spatial variation in wind speed, temperature, and relative humidity at 2m above the ground. The windbreaks significantly reduced wind speed; minimum wind speed was at two times the windbreak height (2H) behind dense (17 [percent] porosity) redcedar and at 6H behind relatively porous (20 [percent] porosity) cadaghi when the wind direction was nearly perpendicular to the windbreak. Wind speed at 2H behind eastern redcedar was approximately 5 [percent] of the open wind speed and at 6H behind cadaghi was approximately 3-30 [percent]. Wind speed at 14H behind cadaghi and redcedar windbreak was approximately 60 [percent] and 80 [percent] of the open wind speed, respectively. Temperature behind both windbreaks was relatively warmer than in the open. However, the extent of temperature and relative humidity modification was less compared to wind speed. Windbreaks are an effective use of forest trees to modify microclimate and appreciably enhance Florida farm production.Bijay Tamang (1), Donald L Rockwood1 and Michael G. Andreu (2) ; 1. PO Box 110410, School of Forest Resources and Conservation, University of Florida, Gainesville, FL 32611. 2. SFRC, University of Florida, Gulf Coast REC - Plant City, 1200 N Park Road, Plant City, FL 33563.Includes bibliographical references

HIV-1 co-infection does not reduce exposure to rifampicin, isoniazid, and pyrazinamide in South African tuberculosis outpatients

There are contrasting data in the literature about antituberculosis plasma drug concentrations in HIV-1-coinfected patients. We report the pharmacokinetics of rifampin, isoniazid, and pyrazinamide in a cohort of patients being treated for active tuberculosis, the majority of whom were coinfected with HIV-1 and had commenced antiretroviral therapy within 2 months of starting antituberculosis treatment. We also examined the association between antituberculosis drug concentrations and reported drug side effects at the 2-month clinical review. One hundred patients with pulmonary tuberculosis (65% coinfected with HIV-1) were intensively sampled to determine rifampin, isoniazid, and pyrazinamide plasma concentrations after 7 to 8 weeks of a daily quadruple-therapy regimen dosed according to World Health Organization (WHO) weight bands. Pharmacokinetic parameters were determined for each patient by using nonlinear mixed-effects models. HIV-1-coinfected patients had lower clearance rates for rifampin (21% decrease) and isoniazid (23% decrease) than HIV-1-uninfected patients, with resulting higher areas under the concentration-time curve from 0 to 24 h (AUC0–24) and maximum concentrations of drug in serum (Cmax). Antiretroviral therapy (ART) that included double-standard-dose lopinavir/ritonavir further lowered rifampin clearance, by 46%, and increased the AUC0–24. The current uniform dosing (per kilogram of body weight) across WHO weight bands was associated with a trend of decreased pharmacokinetic exposures for the lowest weight band. Use of fat-free mass as opposed to total body weight for allometric scaling of clearance significantly improved the model. Ambulant HIV-1-coinfected patients, the majority of whom were coprescribed ART, did not have reduced antituberculosis drug concentrations compared to HIV-1-uninfected patients

Concentration-dependent antagonism and culture conversion in pulmonary tuberculosis

Background There is scant evidence to support target drug exposures for optimal tuberculosis outcomes. We therefore assessed whether pharmacokinetic/pharmacodynamic (PK/PD) parameters could predict 2-month culture conversion. Methods One hundred patients with pulmonary tuberculosis (65% HIV-co-infected) were intensively sampled to determine rifampicin, isoniazid and pyrazinamide plasma concentrations after 7-8 weeks of therapy, and pharmacokinetic parameters determined using non-linear-mixed-effects models. Detailed clinical data and sputum for culture were collected at baseline, 2 and 5-6 months. Minimum inhibitory concentrations (MIC) were determined on baseline isolates. Multivariate logistic regression and the assumption-free multivariate adaptive regression splines (MARS) were used to identify clinical and PK/PD predictors of 2-month culture conversion. Potential PK/PD predictors included 24-hour-area-under-the-curve (AUC0-24), peak concentration (Cmax), AUC0-24/MIC, Cmax/MIC and % time that concentrations persisted above MIC (%TMIC). Results 26% of patients had Cmax (mg/L) of rifampicin4.6 mg/L, higher isoniazid exposures were associated with improved rates of culture conversion. Conclusions PK/PD analyses using MARS identified isoniazid Cmax and rifampicin Cmax/MIC thresholds below which there is concentration-dependent antagonism that reduces 2-month sputum culture conversion

Frailty in primary care: a review of its conceptualization and implications for practice

Frail, older patients pose a challenge to the primary care physician who may often feel overwhelmed by their complex presentation and tenuous health status. At the same time, family physicians are ideally suited to incorporate the concept of frailty into their practice. They have the propensity and skill set that lends itself to patient-centred care, taking into account the individual subtleties of the patient's health within their social context. Tools to identify frailty in the primary care setting are still in the preliminary stages of development. Even so, some practical measures can be taken to recognize frailty in clinical practice and begin to address how its recognition may impact clinical care. This review seeks to address how frailty is recognised and managed, especially in the realm of primary care

L-systems in Geometric Modeling

We show that parametric context-sensitive L-systems with affine geometry interpretation provide a succinct description of some of the most fundamental algorithms of geometric modeling of curves. Examples include the Lane-Riesenfeld algorithm for generating B-splines, the de Casteljau algorithm for generating Bezier curves, and their extensions to rational curves. Our results generalize the previously reported geometric-modeling applications of L-systems, which were limited to subdivision curves.Comment: In Proceedings DCFS 2010, arXiv:1008.127

Four patients with a history of acute exacerbations of COPD: implementing the CHEST/Canadian Thoracic Society guidelines for preventing exacerbations

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