The Threshold Bias Model: A Mathematical Model for the Nomothetic Approach of Suicide

Comparative and predictive analyses of suicide data from different countries are difficult to perform due to varying approaches and the lack of comparative parameters.A simple model (the Threshold Bias Model) was tested for comparative and predictive analyses of suicide rates by age. The model comprises of a six parameter distribution that was applied to the USA suicide rates by age for the years 2001 and 2002. Posteriorly, linear extrapolations are performed of the parameter values previously obtained for these years in order to estimate the values corresponding to the year 2003. The calculated distributions agreed reasonably well with the aggregate data. The model was also used to determine the age above which suicide rates become statistically observable in USA, Brazil and Sri Lanka.The Threshold Bias Model has considerable potential applications in demographic studies of suicide. Moreover, since the model can be used to predict the evolution of suicide rates based on information extracted from past data, it will be of great interest to suicidologists and other researchers in the field of mental health

An estimate of carbon emissions from 2004 wildfires across Alaskan Yukon River Basin

© 2007 Tan et al; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution Licens

La escritura y los procesos de occidentalización del mito y legitimación de la imagen en Las Postrimerías de Carabuco

Commissioned by Joseph de Arellano, parish priest of Carabuco (current Bolivia), the painter José López de los Ríos executed a series of four paintings on the theme of the Last Things in 1683. At the bottom of these paintings he included a narrative cycle of thirty scenes depicting the coming of an apostle to the Andes, and the story of the Cross left by said apostle at Carabuco. These episodes were introduced into half-divided circles, reserving the top for the iconography and the bottom for the written word. This work aims to rethink the relationship between images and writing and demonstrate, in this particular case, that the inclusion of writing worked as an agent of legitimization of iconographic representation in order to Occidentalize the oral Andean tradition.Por encargo del cura doctrinero de Carabuco, Joseph de Arellano, el pintor José López de los Ríos realizó hacia 1683 una serie de cuatro lienzos sobre el tema de las Postrimerías en donde se incluyó un ciclo narrativo de treinta escenas representando el paso de un apóstol por los Andes y la historia de la Cruz que habría dejado en Carabuco. Estos episodios fueron presentados al interior de círculos divididos en dos mitades: reservando la parte superior a la representación iconográfica y la inferior a la escritura. Este trabajo pretende reflexionar sobre las interrelaciones icono-textuales que se entablan en los lienzos realizados por José López de los Ríos, demostrando que la inclusión de la escritura, funcionó como agente de occidentalización y legitimación de la representación iconográfica de una historia que encuentra sus orígenes en relatos orales andinos de tiempos inmemoriales

The Influence of Recent Climate Change on Tree Height Growth Differs with Species and Spatial Environment

Tree growth has been reported to increase in response to recent global climate change in controlled and semi-controlled experiments, but few studies have reported response of tree growth to increased temperature and atmospheric carbon dioxide (CO2) concentration in natural environments. This study addresses how recent global climate change has affected height growth of trembling aspen (Populus tremuloides Michx) and black spruce (Picea mariana Mill B.S.) in their natural environments. We sampled 145 stands dominated by aspen and 82 dominated by spruce over the entire range of their distributions in British Columbia, Canada. These stands were established naturally after fire between the 19th and 20th centuries. Height growth was quantified as total heights of sampled dominant and co-dominant trees at breast-height age of 50 years. We assessed the relationships between 50-year height growth and environmental factors at both spatial and temporal scales. We also tested whether the tree growth associated with global climate change differed with spatial environment (latitude, longitude and elevation). As expected, height growth of both species was positively related to temperature variables at the regional scale and with soil moisture and nutrient availability at the local scale. While height growth of trembling aspen was not significantly related to any of the temporal variables we examined, that of black spruce increased significantly with stand establishment date, the anomaly of the average maximum summer temperature between May-August, and atmospheric CO2 concentration, but not with the Palmer Drought Severity Index. Furthermore, the increase of spruce height growth associated with recent climate change was higher in the western than in eastern part of British Columbia. This study demonstrates that the response of height growth to recent climate change, i.e., increasing temperature and atmospheric CO2 concentration, did not only differ with tree species, but also their growing spatial environment

Evolutionary ecology of mycorrhizal functional diversity in agricultural systems

The root systems of most agronomic crops are colonized by diverse assemblages of arbuscular mycorrhizal fungi (AMF), varying in the functional benefits (e.g. nutrient transfer, pathogen protection, water uptake) provided to hosts. Little is known about the evolutionary processes that shape the composition of these fungal assemblages, nor is it known whether more diverse assemblages are beneficial to crop productivity. In this review we aim to identify the evolutionary selection pressures that shape AMF diversity in agricultural systems and explore whether promotion of AMF diversity can convincingly be linked to increases in agricultural productivity and/or sustainability. We then ask whether farmers can (and should) actively modify evolutionary selection pressures to increase AMF functioning. We focus on three agriculturally imposed selection regimes: tillage, fertilization, and continuous monoculture. We find that the uniform nature of these practices strongly selects for dominance of few AMF species. These species exhibit predictable, generally non-beneficial traits, namely heavy investment in reproduction at the expense of nutrient scavenging and transfer processes that are beneficial for hosts. A number of focus-points are given based on empirical and theoretical evidence that could be utilized to slow down negative selection pressures on AMF functioning, therein increasing crop benefit

A novel receptor-type protein tyrosine phosphatase is expressed during neurogenesis in the olfactory neuroepithelium

Tyrosine phosphorylation plays a central role in the control of neuronal cell development and function. Yet, few neuronal protein tyrosine phosphatases (PTPs) have been identified. We examined rat olfactory neuroepithelium for expression of novel PTPs potentially important in neuronal development and regeneration. Using the polymerase chain reaction with degenerate DNA oligomers directed to the conserved tyrosine phosphatase domain, we identified 6 novel tyrosine phosphatases. One of these, PTP NE-3, is a receptor-type PTP expressed selectively in both rat brain and olfactory neuroepithelium. In the olfactory neuroepithelium, PTP NE-3 expression is restricted to neurons and describes a novel pattern of expression with a high level in the immature neurons and a lower level in mature olfactory sensory neurons.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/30663/1/0000306.pd

Mapping of Forest Types in Alaskan Boreal Forests Using SAR Imagery

Mapping of forest types in the Tanana river flood-plain, interior Alaska, is performed using a maximum-a-posteriori Bayesian classifier applied on SAR data acquired by the NASA/JPL three-frequency polarimetric AIRSAR system on several dates. Five vegetation types are separated, dominated by 1) white spruce, 2) balsam poplar, 3) black spruce, 4) alder/ willow shrubs, and 5) bog/fen/nonforest vegetation. Open water of rivers and lakes is also separated. Accuracy of forest classification is investigated as a function of frequency and polarization of the radar, as well as the forest seasonal state, which includes winter/frozen, winter/thawed, spring/flooded, spring/ unflooded, and summer/dry conditions. Classifications indicate that C-band is a more useful frequency for separating forest types than L or P-bands, and HV polarization is the most useful polarization at all frequencies. The highest classification accuracy, with 90 percent of forest pixels classified correctly, is obtained by combining L-band HV and C-band HV data acquired in spring as seasonal river flooding recedes and before deciduous tree species have leaves. In 17 forest stands for which actual percentages of each tree species are known, the same radar data are capable of predicting tree species composition with less than 10 percent error. For the same combination of observation channels, classification accuracy is 79 percent in spring on a day of intense river flooding, and 62 percent on a dry summer day with leaves on deciduous trees. In winter, using 4-look SAR data instead of 16-look, classification accuracy is 55 percent on a frozen day, and 76 percent on a thawed day. White spruce and balsam poplar stands are best separated in thawed conditions when balsam poplar trees have no leaves. From our classification, we predict that current and future spaceborne SAR systems will have limited mapping capabilities when used alone. Yet, RADARSAT combined with J-ERS-1 and ERS-1 could resolve forest types with 80 percent accuracy, separate nonforest areas resulting from commercial logging or forest wildfire, and map river edges. For comparison, a combination of green, red, and near-infrared radiance data acquired by SPOT-2 on a dry summer day yields a classification accuracy of 83 percent for the same forest stands, with limited success in distinguishing among deciduous forest types and among coniferous forest types. © 1994 IEE

Mapping of Forest Types in Alaskan Boreal Forests Using SAR Imagery

Mapping of forest types in the Tanana river flood-plain, interior Alaska, is performed using a maximum-a-posteriori Bayesian classifier applied on SAR data acquired by the NASA/JPL three-frequency polarimetric AIRSAR system on several dates. Five vegetation types are separated, dominated by 1) white spruce, 2) balsam poplar, 3) black spruce, 4) alder/ willow shrubs, and 5) bog/fen/nonforest vegetation. Open water of rivers and lakes is also separated. Accuracy of forest classification is investigated as a function of frequency and polarization of the radar, as well as the forest seasonal state, which includes winter/frozen, winter/thawed, spring/flooded, spring/ unflooded, and summer/dry conditions. Classifications indicate that C-band is a more useful frequency for separating forest types than L or P-bands, and HV polarization is the most useful polarization at all frequencies. The highest classification accuracy, with 90 percent of forest pixels classified correctly, is obtained by combining L-band HV and C-band HV data acquired in spring as seasonal river flooding recedes and before deciduous tree species have leaves. In 17 forest stands for which actual percentages of each tree species are known, the same radar data are capable of predicting tree species composition with less than 10 percent error. For the same combination of observation channels, classification accuracy is 79 percent in spring on a day of intense river flooding, and 62 percent on a dry summer day with leaves on deciduous trees. In winter, using 4-look SAR data instead of 16-look, classification accuracy is 55 percent on a frozen day, and 76 percent on a thawed day. White spruce and balsam poplar stands are best separated in thawed conditions when balsam poplar trees have no leaves. From our classification, we predict that current and future spaceborne SAR systems will have limited mapping capabilities when used alone. Yet, RADARSAT combined with J-ERS-1 and ERS-1 could resolve forest types with 80 percent accuracy, separate nonforest areas resulting from commercial logging or forest wildfire, and map river edges. For comparison, a combination of green, red, and near-infrared radiance data acquired by SPOT-2 on a dry summer day yields a classification accuracy of 83 percent for the same forest stands, with limited success in distinguishing among deciduous forest types and among coniferous forest types. © 1994 IEE