1,834 research outputs found
Impact of Land Use Changes on Soil Quality of a Biosphere Reserve in Southwestern Nigeria
Many primary forests in the tropical regions of the world have been converted into degraded secondary or intensively used agricultural areas. Using the Spatial Analogue technique of studying ecosystem dynamics, soil impact of deforestation and conversion was evaluated by comparing soil properties under the natural forest, secondary regrowth of a logged-over forest, monoculture plantation of Cedrela odorata (Linn), and maize/cassava farm at 0 10, 10 20 and 20 30cm soil depths. % sand decreased with soil depth in all the land use types and was significantly different between the natural forest and each of the logged-over forest regrowth, monoculture plantation and farmland except at 0 10cm depth. % Clay increased with soil depth but did not vary significantly among land use types except at 20 30cm depth. Available phosphorus decreased gradually with soil depth in all land use types with the natural forest and farmland having the highest and lowest mean values respectively. Organic matter varied significantly between each of the natural forest, logged-over forest regrowth and monoculture plantation, with the farmland at the three soil depths. Total nitrogen was generally low in all land use types, though, the natural forest compared better than the others. Soil pH, calcium, magnesium, effective cation exchange capacity, and percentage base saturation decreased with soil depth in all land use types with the natural forest having higher mean values than the others. Indices of change computed for organic matter, total nitrogen, available phosphorus, calcium, magnesium, potassium, effective cation exchange capacity and percentage base saturation, showed that soil management in the introduced land use types, is tending away from sustainability. Inter-cropping with nutrient-regenerating agroforestry trees on the farmland and the use of low-impact logging techniques are suggested for soil conservation
Dynamic Python-Based Method Provides Quantitative Analysis of Intercellular Junction Organization During S. pneumoniae Infection of the Respiratory Epithelium
Many respiratory pathogens compromise epithelial barrier function during lung infection by disrupting intercellular junctions, such as adherens junctions and tight junctions, that maintain intercellular integrity. This includes Streptococcus pneumoniae, a leading cause of pneumonia, which can successfully breach the epithelial barrier and cause severe infections such as septicemia and meningitis. Fluorescence microscopy analysis on intercellular junction protein manipulation by respiratory pathogens has yielded major advances in our understanding of their pathogenesis. Unfortunately, a lack of automated image analysis tools that can tolerate variability in sample-sample staining has limited the accuracy in evaluating intercellular junction organization quantitatively. We have created an open source, automated Python computer script called “Intercellular Junction Organization Quantification” or IJOQ that can handle a high degree of sample-sample staining variability and robustly measure intercellular junction integrity. In silico validation of IJOQ was successful in analyzing computer generated images containing varying degrees of simulated intercellular junction disruption. Accurate IJOQ analysis was further confirmed using images generated from in vitro and in vivo bacterial infection models. When compared in parallel to a previously published, semi-automated script used to measure intercellular junction organization, IJOQ demonstrated superior analysis for all in vitro and in vivo experiments described herein. These data indicate that IJOQ is an unbiased, easy-to-use tool for fluorescence microscopy analysis and will serve as a valuable, automated resource to rapidly quantify intercellular junction disruption under diverse experimental conditions
Conjugated Linoleic Acid Supplementation Does Not Reduce Visceral Adipose Tissue in Middle-Aged Men Engaged in a Resistance-Training Program
Conjugated linoleic acid (CLA) supplementation has shown convincing effects at reducing body fat in animals; yet human study results have been somewhat inconclusive. The purpose of this study is to determine whether four weeks of CLA supplementation, the approximate length of a commercial package, can result in a positive change in visceral adipose tissue in resistance-trained middle-aged men. Thirty overweight and moderately obese, but otherwise healthy male subjects (aged 35 to 55 years) currently involved in resistance training, were randomly assigned into CLA and placebo groups in a double-blind, placebo controlled approach. The study lasted for 12 weeks and consisted of three four-week periods. During the first four weeks (run-in period) each subject received placebo (4 g safflower oil). Throughout the next four weeks (supplementation period), the placebo group continued receiving placebo, while the CLA group received 3.2 g/d of CLA. During the final four weeks (run-out period) all subjects received the placebo. Computed tomography (CT) scans were used to measure visceral adipose tissue (VAT) at weeks 4, 8 and 12. No significant reduction in VAT cross-sectional area was determined in the CLA group during the study. On the contrary, a significant reduction in cross-sectional area of VAT of 23.12 cm2 during the supplementation period was measured in the placebo group, which was abated during the run-out period. Our results suggest that CLA supplementation of 3.2 g/d for four weeks does not promote decreases in VAT in middle-aged men currently participating in a resistance-training program
How do people with asthma use Internet sites containing patient experiences?
Objective: To understand how people engage with websites containing patient authored accounts of health and illness. To examine how people with asthma navigate their way through this information and make use of the patient experiences they find.
Methods: Twenty-nine patients with diagnoses ranging from mild to severe asthma were shown a range of websites, some containing patient experiences, and selected two sites to explore further. They discussed their choices in a series of focus groups and interviews.
Results: Participants were influenced initially by the design quality of the sites and were subsequently drawn to websites containing patient experiences but only when contributions were from similar people offering ‘relevant stories’. The experiences reminded participants of the serious nature of the disease, provided new insights into the condition and an opportunity to reflect upon the role of the disease in their lives.
Conclusion: For people with asthma websites containing other patients’ personal experiences can serve as a useful information resource, refresh their knowledge and ensure their health behaviours are appropriate and up-to-date.
Practice Implications: Health professionals should consider referring asthma patients to appropriate websites whilst being aware that online experiences are most engaging when they resonate with the participants own situation
Relationship among surgical volume, repair quality, and perioperative outcomes for repair of mitral insufficiency in a mitral valve reference center
ObjectiveAlthough it has been demonstrated that the repair rates and quality of the repair of mitral insufficiency are superior in mitral valve reference centers, it has not been studied whether an advantage exists for perioperative morbidity and mortality. We report 1 surgeon's evolution over 7 years, specifically considering the changes in perioperative morbidity and mortality.MethodsWe performed a retrospective review of 1054 patients who had undergone elective, day-of-surgery-admission mitral valve repair by a single surgeon (D.H.A.) at our institution from April 2005 to June 2012. The outcome variables studied were operative mortality (30-day or in-hospital mortality, if longer), length of stay, low cardiac output state after cardiopulmonary bypass, and major morbidity.ResultsThe overall operative mortality was 0.58%. Of the 1054 patients, 31% developed a low cardiac output state postoperatively and 6.52% experienced at least 1 of the composite morbidity events. Increased aortic crossclamp times were significantly and independently associated with a low cardiac output state, length of stay, and morbidity. When divided by service year, a statistically and clinically significant decrease was found in the aortic crossclamp time, despite an increase in the complexity of cases. The morbidity decreased concurrently with the decreases in crossclamp times.ConclusionsAs the number of mitral valve repairs performed each year by a single surgeon at a single institution increased, morbidity, including postoperative heart function and length of stay, decreased. This was demonstrated to occur in large part from a reduction in the aortic crossclamp times, despite an increase in the complexity of the procedures. This further demonstrates the value of reference centers for mitral valve surgery
Structures of the Ets Protein DNA-binding Domains of Transcription Factors Etv1, Etv4, Etv5, and Fev: Determinants of DNA Binding and Redox Regulation by Disulfide Bond Formation.
Ets transcription factors, which share the conserved Ets DNA-binding domain, number nearly 30 members in humans and are particularly involved in developmental processes. Their deregulation following changes in expression, transcriptional activity, or by chromosomal translocation plays a critical role in carcinogenesis. Ets DNA binding, selectivity, and regulation have been extensively studied; however, questions still arise regarding binding specificity outside the core GGA recognition sequence and the mode of action of Ets post-translational modifications. Here, we report the crystal structures of Etv1, Etv4, Etv5, and Fev, alone and in complex with DNA. We identify previously unrecognized features of the protein-DNA interface. Interactions with the DNA backbone account for most of the binding affinity. We describe a highly coordinated network of water molecules acting in base selection upstream of the GGAA core and the structural features that may account for discrimination against methylated cytidine residues. Unexpectedly, all proteins crystallized as disulfide-linked dimers, exhibiting a novel interface (distant to the DNA recognition helix). Homodimers of Etv1, Etv4, and Etv5 could be reduced to monomers, leading to a 40-200-fold increase in DNA binding affinity. Hence, we present the first indication of a redox-dependent regulatory mechanism that may control the activity of this subset of oncogenic Ets transcription factors
The Collision Between The Milky Way And Andromeda
We use a N--body/hydrodynamic simulation to forecast the future encounter
between the Milky Way and the Andromeda galaxies, given current observational
constraints on their relative distance, relative velocity, and masses. Allowing
for a comparable amount of diffuse mass to fill the volume of the Local Group,
we find that the two galaxies are likely to collide in a few billion years -
within the Sun's lifetime. During the the interaction, there is a chance that
the Sun will be pulled away from its present orbital radius and reside in an
extended tidal tail. The likelihood for this outcome increases as the merger
progresses, and there is a remote possibility that our Sun will be more tightly
bound to Andromeda than to the Milky Way before the final merger. Eventually,
after the merger has completed, the Sun is most likely to be scattered to the
outer halo and reside at much larger radii (>30 kpc). The density profiles of
the stars, gas and dark matter in the merger product resemble those of
elliptical galaxies. Our Local Group model therefore provides a prototype
progenitor of late--forming elliptical galaxies.Comment: accepted to MNRA
Nuclear Shadowing in Electro-Weak Interactions
Shadowing is a quantum phenomenon leading to a non-additivity of electroweak
cross sections on nucleons bound in a nucleus. It occurs due to destructive
interference of amplitudes on different nucleons. Although the current
experimental evidence for shadowing is dominated by charged-lepton nucleus
scattering, studies of neutrino nucleus scattering have recently begun and
revealed unexpected results.Comment: 77 pages, 57 figures. To be published in "Progress in Particle and
Nuclear Physics" 201
Does a perception of increased blood safety mean increased blood transfusion? An assessment of the risk compensation theory in Canada
BACKGROUND: The risk compensation theory is a widely used concept in transport economics to analyze driver risk behaviour. This article explores the feasibility of applying the theory in blood transfusion to raise important questions regarding the increased blood safety measures and their possible effects on blood usage (e.g., the appropriateness in transfusion). Further, it presents the findings of a pilot survey of physicians in Canada. DISCUSSION: While studies have attempted to define transfusion appropriateness, this article argues that if the risk compensation theory holds true for transfusion practice, physicians may actually be transfusing more. This may increase the possibility of contracting other unknown risks, such as the variant Creutzfeldt-Jakob Disease (vCJD), as well as increasing the risk of non-infectious transfusion risks, such as transfusion reactions. SUMMARY: A much larger study involving psychosocial assessment of physician decision making process to fully assess physician behaviour within the context of risk compensation theory and transfusion practice in Canada is needed to further explore this area
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