Necromass in forests of Madre de Dios, Peru: a comparison between terra firme and lowland forests

Stocks of dead wood or necromass represent an important portion of biomass and nutrients in tropical forests. The objectives of this study were: 1) to evaluate and compare the necromass of "terra firme" and lowlands forests, (2) to study the relationship between necromass, above-ground biomass and wood density, and (3) to estimate the necromass of the department of Madre de Dios, Peru. Stocks of necromass and above-ground biomass were estimated at three different locations using permanent plots and line intercept transects. The average volume of necromass for the three sites was 72.9 m3 ha-1 with an average weight varying between 24.8 and 30.7 Mg ha-1, depending on the estimations of dead wood density used for the calculations. Terra firme forests had significantly higher stocks of necromass than lowland forests. The amount of necromass was 11% of the total above-ground biomass in Madre de Dios forests. The total stock of carbon stored in dead wood for the entire department of Madre de Dios was estimated to be approximately 100 mega tonnes of carbon. This is ten times more than the annual fossil fuel emissions of Peru between 2000 and 2008. The substantial stocks of necromass emphasize the importance of these types of field studies, considering that this component of tropical forest carbon cannot be detected using other methods such as satellite remote sensing

Chronic pain in the community: a survey in a township in Mthatha, Eastern Cape, South Africa

Background: Comprehensive information is needed on the epidemiology and burden of chronic pain in the population for the development of appropriate health interventions. This study aimed to determine the prevalence, severity, risk indicators and responses of chronic pain among adults in Ngangelizwe, Mthatha, South Africa.Method: A cross-sectional survey utilising structured interviews of a sample of adult residents was used. Interviews elicited information on socio-demographic characteristics, general health status, and the prevalence, duration, frequency, severity, activity limitation and impact of chronic pain.Results: More than 95% (n = 473) of the sampled adults participated in the study. Of these, 182 [38.5%, 95% confidence interval (CI): 36.3-42.5%] reported chronic pain in at least one anatomical site. The most common pain sites were the back and head. The median pain score was 5 on a scale of 0 to 10 [interquartile range (IQR) = 4-7] and the median number of sites of pain was 1 (IQR = 1-2). Female gender [odds ratio (OR) = 2.6, 95% CI: 1.7-3.9] and being older than 50 years of age (OR = 3.5, 95% CI: 2.6-4.1) were identified as risk indicators for chronic pain in the sample. Over 65% of respondents reported that they self-treated; 92.1% had consulted with a doctor or nurse, 13.6% consulted a traditional healer, and 34.5% consulted a pharmacist because of their pain. Despite this, over 50% reported that relief of their pain was transient.Conclusion: Chronic pain is a common general complaint in this community, but there is a need for focused attention on women and the elderly.Keywords: chronic pain, community-based survey, epidemiology, Mthatha, Eastern Cape, South Afric

Existence and Exponential Stability of Positive Almost Periodic Solutions for a Model of Hematopoiesis

By employing the contraction mapping principle and applying Gronwall-Bellman's inequality, sufficient conditions are established to prove the existence and exponential stability of positive almost periodic solution for nonlinear impulsive delay model of hematopoiesis.The research of Juan J. Nieto has been partially supported by Ministerio de Educacion y Ciencia and FEDER, project MTM2007-61724S

Experimental modulation of capsule size in Cryptococcus neoformans

Experimental modulation of capsule size is an important technique for the study of the virulence of the encapsulated pathogen Cryptococcus neoformans. In this paper, we summarize the techniques available for experimental modulation of capsule size in this yeast and describe improved methods to induce capsule size changes. The response of the yeast to the various stimuli is highly dependent on the cryptococcal strain. A high CO(2) atmosphere and a low iron concentration have been used classically to increase capsule size. Unfortunately, these stimuli are not reliable for inducing capsular enlargement in all strains. Recently we have identified new and simpler conditions for inducing capsule enlargement that consistently elicited this effect. Specifically, we noted that mammalian serum or diluted Sabouraud broth in MOPS buffer pH 7.3 efficiently induced capsule growth. Media that slowed the growth rate of the yeast correlated with an increase in capsule size. Finally, we summarize the most commonly used media that induce capsule growth in C. neoformans

Hemispheric Asymmetry of Globus Pallidus Explains Reward-related Posterior Alpha Modulation in Humans

While subcortical structures such as the basal ganglia (BG) have been widely explored in relation to motor control, recent evidence suggests that their mechanisms extend to the domain of attentional switching. We here investigated the subcortical involvement in reward related top-down control of visual alpha-band oscillations (8 – 13 Hz), which have been consistently linked to the mechanisms supporting the allocation of visual spatial attention. Given that items associated with contextual saliency (e.g. monetary reward or loss) attract attention, it is not surprising that alpha oscillations are further modulated by the saliency properties of the visual items. The executive network controlling such reward-dependent modulations of oscillatory brain activity has yet to be fully elucidated. Although such network has been explored in terms of cortico-cortical interaction, it likely relies also on the contribution of subcortical regions. To uncover this, we investigated whether derived measures of subcortical structural asymmetries could predict interhemispheric modulation of alpha power during a spatial attention task. We show that volumetric hemispheric lateralization of globus pallidus (GP) and thalamus (Th) explains individual hemispheric biases in the ability to modulate posterior alpha power. Importantly, for the GP, this effect became stronger when the value-saliency parings in the task increased. Our findings suggest that the Th and GP in humans are part of a subcortical executive control network, differently involved in modulating posterior alpha activity. Further investigation aimed at uncovering the interaction between subcortical and neocortical attentional networks would provide useful insight in future studies

Occipital Alpha and Gamma Oscillations Support Complementary Mechanisms for Processing Stimulus Value Associations.

Selective attention is reflected neurally in changes in the power of posterior neural oscillations in the alpha (8–12 Hz) and gamma (40–100 Hz) bands. Although a neural mechanism that allows relevant information to be selectively processed has its advantages, it may lead to lucrative or dangerous information going unnoticed. Neural systems are also in place for processing rewarding and punishing information. Here, we examine the interaction between selective attention (left vs. right) and stimulus's learned value associations (neutral, punished, or rewarded) and how they compete for control of posterior neural oscillations. We found that both attention and stimulus–value associations influenced neural oscillations. Whereas selective attention had comparable effects on alpha and gamma oscillations, value associations had dissociable effects on these neural markers of attention. Salient targets (associated with positive and negative outcomes) hijacked changes in alpha power—increasing hemispheric alpha lateralization when salient targets were attended, decreasing it when they were being ignored. In contrast, hemispheric gamma-band lateralization was specifically abolished by negative distractors. Source analysis indicated occipital generators of both attentional and value effects. Thus, posterior cortical oscillations support both the ability to selectively attend while at the same time retaining the ability to remain sensitive to valuable features in the environment. Moreover, the versatility of our attentional system to respond separately to salient from merely positively valued stimuli appears to be carried out by separate neural processes reflected in different frequency bands