549 research outputs found
Transients drive the demographic dynamics of plant populations in variable environments
The dynamics of structured plant populations in variable environments can be decomposed into the âasymptoticâ growth contributed by vital rates, and âtransientâ growth caused by deviation from stable stage structure.
We apply this framework to a large, global data base of longitudinal studies of projection matrix models for plant populations. We ask, what is the relative contribution of transient boom and bust to the dynamic trajectories of plant populations in stochastic environments? Is this contribution patterned by phylogeny, growth form or the number of life stages per population and per species?
We show that transients contribute nearly 50% or more to the resulting trajectories, depending on whether transient and stable contributions are partitioned according to their absolute or net contribution to population dynamics.
Both transient contributions and asymptotic contributions are influenced heavily by the number of life stages modelled. We discuss whether the drivers of transients should be considered real ecological phenomena, or artefacts of study design and modelling strategy. We find no evidence for phylogenetic signal in the contribution of transients to stochastic growth, nor clear patterns related to growth form. We find a surprising tendency for plant populations to boom rather than bust in response to temporal changes in vital rates and that stochastic growth rates increase with increasing tendency to boom.
Synthesis. Transient dynamics contribute significantly to stochastic population dynamics but are often overlooked in ecological and evolutionary studies that employ stochastic analyses. Better understanding of transient responses to fluctuating population structure will yield better management strategies for plant populations, and better grasp of evolutionary dynamics in the real world
The Spoken Word Project: Using Poetry in Community Dialogue and Mobilization for HIV Prevention
Spoken word, a form of performance poetry, is a promising approach to HIV/AIDS awareness and prevention, as it has the potential to encourage dialogue among and within communities and address concerns regarding the social stigma present in rural communities. The purpose of this study is to describe the development and implementation of the Spoken Word Project (SWP), an HIV/AIDS pilot intervention in rural North Carolina designed to improve HIV-related attitudes and self-efficacy and decrease stigma through the use of performance poetry. Spoken word is a collaborative effort between residents of two rural counties in North Carolina and Project GRACE (Growing, Reaching, Advocating for Change and Empowerment), a community-based participatory research collaboration aimed at reducing health disparities in African American communities. The project included 15 adult and youth participants. Results indicated that spoken word has the ability to build upon local resources, generate community reflection, and engage a broad spectrum of performers and audiences. Our findings also showed that the effect of stigma and limited community conversations about HIV in rural communities can be abated through the use of spoken word
U.S. Department of Energy Commercial Reference Building Models of the National Building Stock
The U.S. Department of Energy (DOE) Building Technologies Program has set the aggressive goal of producing marketable net-zero energy buildings by 2025. This goal will require collaboration between the DOE laboratories and the building industry. We developed standard or reference energy models for the most common commercial buildings to serve as starting points for energy efficiency research. These models represent fairly realistic buildings and typical construction practices. Fifteen commercial building types and one multifamily residential building were determined by consensus between DOE, the National Renewable Energy Laboratory, Pacific Northwest National Laboratory, and Lawrence Berkeley National Laboratory, and represent approximately two-thirds of the commercial building stock
Determination of Total and Bioavailable Soil Lead from a Shooting Range in Central California.
Lead can pose a significant risk to environmental quality at and around shooting ranges due to its use in bullets and shot. The concentrations of Pb in soils, plants and surficial waters from a shooting range were determined in this study. Soil and plant samples were analyzed for total Pb (US EPA method 3050a) to determine the extent of Pb contamination. The toxicity characteristic leach procedure (TCLP; US EPA method 1311) was followed to ascertain bioavailable Pb. Soil samples ranged from 14.71 to 6346.15 mg Pb kg-1 soil with an average value of 1157.43 (±2000.57) mg Pb kg-1 soil across the shooting range. Plant samples ranged from 632.76 to 2896.00 mg Pb kg-1 plant with an average value of 1410.31 (±1287.11) mg Pb kg-1 plant, demonstrating significant Pb uptake. Bioavailable Pb was highest in the berm at 2038.00 mg Pb kg-1 soil. Sampling at depth showed Pb concentrations of 72.92 mg Pb kg-1 soil. When compared to surface samples (897.96 mg Pb kg-1), this shows some Pb is leaching through the profile. High Pb concentrations were detected in soil samples collected from the drainage (457.84 mg Pb kg-1), while low Pb levels were detected in the stormwater retention pond and sediments (0.11 mg Pb L-1 and 39.36 mg Pb kg-1 respectively). This indicates Pb is being transported through erosion of soil colloids. Elevated Pb levels from soil sampled in the drainage indicate most Pb present is attached to soil colloids and not free (Pb+2) to leach or runoff. Higher concentrations of Pb were detected in plant samples than extracted by TCLP bioavailable Pb estimations. This could present a problem for any pastoral activities and should come under further scrutiny
Recommended from our members
Report and recommendations of salmon anchor habitat strategy work group
The 2003 Oregon Legislature directed the Oregon Department of Forestry (ODF) to convene a citizen work group to review and evaluate the ODF Salmon Anchor Habitat Strategy for state forests in northwest Oregon. In November, 2003 ODF contracted with the Institute for Natural Resources (INR) to support the SAH Work Group. INR designed and oversaw a process for the SAH Work Group that facilitated dialogue among interested parties, scientists, land management
professionals, and policy makers. The goal was to illuminate the SAH policy, identify issues and develop recommendations while respecting the perspectives held by all parties.KEYWORDS:
Pacific northwest,
Trees,
Tillamook,
Environment and Conservation,
Watersheds,
Fishing,
Salmon anchor habitat,
Clatsop,
Endangered species act,
Salmon,
Fish,
Forest,
Oregon plan,
Old growth,
Lumber,
Native Americans,
Oregon Department of Forestry,
Timber,
HB3632,
Fir
Validation of GOSAT SWIR XCOâ and XCHâ Retrieved by PPDF-S Method and Comparison with Full Physics Method
Small RNA combination therapy for lung cancer
MicroRNAs (miRNAs) and siRNAs have enormous potential as cancer therapeutics, but their effective delivery to most solid tumors has been difficult. Here, we show that a new lung-targeting nanoparticle is capable of delivering miRNA mimics and siRNAs to lung adenocarcinoma cells in vitro and to tumors in a genetically engineered mouse model of lung cancer based on activation of oncogenic Kirsten rat sarcoma viral oncogene homolog (Kras) and loss of p53 function. Therapeutic delivery of miR-34a, a p53-regulated tumor suppressor miRNA, restored miR-34a levels in lung tumors, specifically down-regulated miR-34a target genes, and slowed tumor growth. The delivery of siRNAs targeting Kras reduced Kras gene expression and MAPK signaling, increased apoptosis, and inhibited tumor growth. The combination of miR-34a and siRNA targeting Kras improved therapeutic responses over those observed with either small RNA alone, leading to tumor regression. Furthermore, nanoparticle-mediated small RNA delivery plus conventional, cisplatin-based chemotherapy prolonged survival in this model compared with chemotherapy alone. These findings demonstrate that RNA combination therapy is possible in an autochthonous model of lung cancer and provide preclinical support for the use of small RNA therapies in patients who have cancer.National Cancer Institute (U.S.) (Cancer Center Support (Core) Grant P30-CA14051)National Institutes of Health (U.S.) (Grant 2-PO1-CA42063)National Institutes of Health (U.S.) (Grant RO1-EB000244)National Institutes of Health (U.S.) (Grant RO1-CA115527)National Institutes of Health (U.S.) (Grant RO1-CA132091)National Cancer Institute (U.S.) (1K99CA169512)American Association for Cancer Research (Fellowship)Leukemia & Lymphoma Society of America (Fellowship)National Science Foundation (U.S.). Graduate Research Fellowship ProgramMassachusetts Institute of Technology. Presidential FellowshipUnited States. Dept. of Defense (National Defense Science and Engineering Graduate Fellowship
Cliniciansâ response to hyperoxia in ventilated patients in a Dutch ICU depends on the level of FiO2
Hyperoxia may induce pulmonary injury and may increase oxidative stress. In this retrospective database study we aimed to evaluate the response to hyperoxia by intensivists in a Dutch academic intensive care unit. All arterial blood gas (ABG) data from mechanically ventilated patients from 2005 until 2009 were extracted from an electronic storage database of a mixed 32-bed intensive care unit in a university hospital in Amsterdam. Mechanical ventilation settings at the time of the ABG tests were retrieved. The results of 126,778 ABG tests from 5,498 mechanically ventilated patients were retrieved including corresponding ventilator settings. In 28,222 (22%) of the ABG tests the arterial oxygen tension (PaO2) was > 16 kPa (120 mmHg). In only 25% of the tests with PaO2 > 16 kPa (120 mmHg) was the fraction of inspired oxygen (FiO(2)) decreased. Hyperoxia was accepted without adjustment in ventilator settings if FiO(2) was 0.4 or lower. Hyperoxia is frequently seen but in most cases does not lead to adjustment of ventilator settings if FiO(2) <0.41. Implementation of guidelines concerning oxygen therapy should be improved and further research is needed concerning the effects of frequently encountered hyperoxi
Recommended from our members
Neutrinos below 100 TeV from the southern sky employing refined veto techniques to IceCube data
Many Galactic sources of gamma rays, such as supernova remnants, are expected to produce neutrinos with a typical energy cutoff well below 100 TeV. For the IceCube Neutrino Observatory located at the South Pole, the southern sky, containing the inner part of the Galactic plane and the Galactic Center, is a particularly challenging region at these energies, because of the large background of atmospheric muons. In this paper, we present recent advancements in data selection strategies for track-like muon neutrino events with energies below 100 TeV from the southern sky. The strategies utilize the outer detector regions as veto and features of the signal pattern to reduce the background of atmospheric muons to a level which, for the first time, allows IceCube searching for point-like sources of neutrinos in the southern sky at energies between 100 GeV and several TeV in the muon neutrino charged current channel. No significant clustering of neutrinos above background expectation was observed in four years of data recorded with the completed IceCube detector. Upper limits on the neutrino flux for a number of spectral hypotheses are reported for a list of astrophysical objects in the southern hemisphere
- âŠ