Vegetation Responses to Prescribed Burning in a Mixed-conifer Woodland, Cuyamaca Rancho State Park, California

This study reports the results of light intensity prescribed burning on the vegetation of 3 jeffrey pine-black oak woodland sites in Cuyamaca Rancho State Park, California. The 1.2 ha, 85 ha, and 6 ha burn plots were measured for tree and shrub density and basal area 6 months, 1% years, and 2 years following burning for the 3 sites respectively. Each burn site measured was compared against equivalent unburned control plots to help assess the effects of the burning. Density of saplings, seedlings, and herbaceous vegetation was also determined for the woodland understories. Dominance and relative dominance of herbaceous ground cover in meadow areas were obtained to determine the recovery of the bunch grasses. Tree density and basal area were not affected by the burning except •for a slight reduction in the number of trees with very small diameters at breast height (2-8cm). Tree sapling density was greatly reduced in burn plots when compared to control plots. Mean density of tree seedlings also was generally decreased in burn plots except for Quercus agrifolia, Quercus chrysolepis, and Quercus kelloggii, which increased in some study plots in the most recent burn. Density and diversity of herbaceous vegetation were generally increased as a result of the burning. Meadow bunch grasses were recovering well through the thinning of dead grass in bunches. Muhlenbergia rigens recovered 143% of the live foliar cover 3 months following one burn. The greatest change which took place as a result of the burning was a significant reduction in density and basal area of shrubs in the understory. The dominant shrub, Mexican manzanita (Arctostaphylos pungens), averaged a 93% density reduction in the burn plots compared to control plots. Other shrubs such as Arctostaphylos glandulosa, Ceanothus leucodermis, Ceanothus paImeri, Cercocarpus betuloides, and Rhamnus californica were also reduced to a lesser extent

Competitive and Information Effects of Cross‐Border Stock Listings

We examine the effect of 269 cross-border listings on rivals in the listing and domestic markets and find that U.S. rivals experience significant gains whereas domestic rivals do not. Both competitive and information effects are important in explaining the reaction of U.S. rivals. Regarding the competitive effects, the reaction of rivals is less favorable when listings originate in developed countries and more favorable when listing firms do not have prior operating presence in the United States. Regarding the information effects, the reaction is less favorable when listings are combined with equity offerings and more favorable when the listing is the first to occur within an industry

Economies of space and the school geography curriculum

This paper is about the images of economic space that are found in school curricula. It suggests the importance for educators of evaluating these representations in terms of the messages they contain about how social processes operate. The paper uses school geography texts in Britain since the 1970s to illustrate the different ways in which economic space has been represented to students, before exploring some alternative resources that could be used to provide a wider range of representations of economic space. The paper highlights the continued importance of understanding the politics of school knowledge

A complete view of galaxy evolution: panchromatic luminosity functions and the generation of metals

When and how did galaxies form and their metals accumulate? Over the last decade, this has moved from an archeological question to a live investigation: there is now a broad picture of the evolution of galaxies in dark matter halos: their masses, stars, metals and supermassive blackholes. Galaxies have been found and studied in which these formation processes are taking place most vigorously, all the way back in cosmic time to when the intergalactic medium (IGM) was still largely neutral. However, the details of how and why the interstellar medium (ISM) in distant galaxies cools, is processed, recycled and enriched in metals by stars, and fuels active galactic nuclei (AGNs) remain uncertain. In particular, the cooling of gas to fuel star formation, and the chemistry and physics of the most intensely active regions is hidden from view at optical wavelengths, but can be seen and diagnosed at mid- & far-infrared (IR) wavelengths. Rest-frame IR observations are important first to identify the most luminous, interesting and important galaxies, secondly to quantify accurately their total luminosity, and finally to use spectroscopy to trace the conditions in the molecular and atomic gas out of which stars form. In order to map out these processes over the full range of environments and large-scale structures found in the universe - from the densest clusters of galaxies to the emptiest voids - we require tools for deep, large area surveys, of millions of galaxies out to z~5, and for detailed follow-up spectroscopy. The necessary tools can be realized technically. Here, we outline the requirements for gathering the crucial information to build, validate and challenge models of galaxy evolution.Comment: A whitepaper submitted on 15th February 2009 in response to the call from the Astro2010 panel: astro2010.org; uploaded as an 8-page pdf fil

BMQ

BMQ: Boston Medical Quarterly was published from 1950-1966 by the Boston University School of Medicine and the Massachusetts Memorial Hospitals

MRI Radiomic Signature of White Matter Hyperintensities Is Associated With Clinical Phenotypes

Objective: Neuroimaging measurements of brain structural integrity are thought to be surrogates for brain health, but precise assessments require dedicated advanced image acquisitions. By means of quantitatively describing conventional images, radiomic analyses hold potential for evaluating brain health. We sought to: (1) evaluate radiomics to assess brain structural integrity by predicting white matter hyperintensities burdens (WMH) and (2) uncover associations between predictive radiomic features and clinical phenotypes. Methods: We analyzed a multi-site cohort of 4,163 acute ischemic strokes (AIS) patients with T2-FLAIR MR images with total brain and WMH segmentations. Radiomic features were extracted from normal-appearing brain tissue (brain mask-WMH mask). Radiomics-based prediction of personalized WMH burden was done using ElasticNet linear regression. We built a radiomic signature of WMH with stable selected features predictive of WMH burden and then related this signature to clinical variables using canonical correlation analysis (CCA). Results: Radiomic features were predictive of WMH burden (R-2 = 0.855 +/- 0.011). Seven pairs of canonical variates (CV) significantly correlated the radiomics signature of WMH and clinical traits with respective canonical correlations of 0.81, 0.65, 0.42, 0.24, 0.20, 0.15, and 0.15 (FDR-corrected p-values(CV1-6) < 0.001, p-value(CV7) = 0.012). The clinical CV1 was mainly influenced by age, CV2 by sex, CV3 by history of smoking and diabetes, CV4 by hypertension, CV5 by atrial fibrillation (AF) and diabetes, CV6 by coronary artery disease (CAD), and CV7 by CAD and diabetes. Conclusion: Radiomics extracted from T2-FLAIR images of AIS patients capture microstructural damage of the cerebral parenchyma and correlate with clinical phenotypes, suggesting different radiographical textural abnormalities per cardiovascular risk profile. Further research could evaluate radiomics to predict the progression of WMH and for the follow-up of stroke patients' brain health.Peer reviewe

Stigma narratives: LGBT transitions and identities in Malta

This article is available open access through the publisher’s website at the link below. Copyright @ 2011 A B Academic Publishers.This article considers narratives of transition experiences of a group of Lesbian, Gay, Bisexual and Transgender (LGBT) young people in Malta. The article draws on Goffman's concept of stigma and uses this to explore transitions in a society that retains some traditional characteristics, particularly the code of honour and shame, although mediated by aspects of modernity. Interviews were undertaken with 15 young people with the goal of producing narratives. The article analyses the experience of stigma, its effects and how young people manage its consequences. It concludes by drawing attention to the pervasive nature of stigma and the importance of structure, agency and reflexivity in youth transitions. In particular stigma remains an important feature of societies in which hetero-normative sexuality remains dominant

Particulate-Matter Emission Estimates from Agricultural Spring-Tillage Operations Using LIDAR and Inverse Modeling

Particulate-matter (PM) emissions from a typical spring agricultural tillage sequence and a strip–till conservation tillage sequence in California’s San Joaquin Valley were estimated to calculate the emissions control efficiency (η) of the strip–till conservation management practice (CMP). Filter-based PM samplers, PM-calibrated optical particle counters (OPCs), and a PM-calibrated light detection and ranging (LIDAR) system were used to monitored upwind and downwind PM concentrations during May and June 2008. Emission rates were estimated through inverse modeling coupled with the filter and OPC measurements and through applying a mass balance to the PM concentrations derived from LIDAR data. Sampling irregularities and errors prevented the estimation of emissions from 42% of the sample periods based on filter samples. OPC and LIDAR datasets were sufficiently complete to estimate emissions and the strip–till CMP η, which were ∼90% for all size fractions in both datasets. Tillage time was also reduced by 84%. Calculated emissions for some operations were within the range of values found in published studies, while other estimates were significantly higher than literature values. The results demonstrate that both PM emissions and tillage time may be reduced by an order of magnitude through the use of a strip–till conservation tillage CMP when compared to spring tillage activities

Abrupt transition to heightened poliomyelitis epidemicity in England and Wales, 1947–1957, associated with a pronounced increase in the geographical rate of disease propagation

The abrupt transition to heightened poliomyelitis epidemicity in England and Wales, 1947–1957, was associated with a profound change in the spatial dynamics of the disease. Drawing on the complete record of poliomyelitis notifications in England and Wales, we use a robust method of spatial epidemiological analysis (swash-backwash model) to evaluate the geographical rate of disease propagation in successive poliomyelitis seasons, 1940–1964. Comparisons with earlier and later time periods show that the period of heightened poliomyelitis epidemicity corresponded with a sudden and pronounced increase in the spatial rate of disease propagation. This change was observed for both urban and rural areas and points to an abrupt enhancement in the propensity for the geographical spread of polioviruses. Competing theories of the epidemic emergence of poliomyelitis in England and Wales should be assessed in the light of this evidence