897 research outputs found
Influence of Community Characteristics on Urban Forest Management Programs in New York State
US state and federal urban forest management agencies endeavor to support municipal forestry programs. However, the variation in programs within and among states may complicate support delivery. Municipal programs are often categorized by population size and community affluence to identify common characteristics and needs and facilitate support. To describe local urban forest management programs in New York State, a survey of municipalities gathered information on urban forest management program components, intentions, and needs. In addition to examining the contributions of population size and affluence, this study also evaluated the influence of metropolitan areas on programs in small municipalities and compared all community categorizations using national program standards. The survey revealed that a high percentage of municipalities plant and maintain trees. Nearly half of municipalities have tree inventories and street tree advisory boards, and a low percentage have an urban forest management plan. Almost all reported needing technical and educational assistance. Larger communities were more likely to have a comprehensive urban forest management program than medium-sized communities, and medium communities were more likely than small communities. Communities with high median household income (MHI) were more likely to have comprehensive urban forestry management programs than less affluent communities. However, low MHI and middle MHI communities had equivalent programs. Small municipalities in counties with large metropolitan areas possessed attributes similar to larger municipalities, compared to small communities in counties without these areas. This may indicate that proximity to a large metropolis has the potential to provide a small community with additional resources. These results suggest that smaller and less affluent communities, especially those outside counties containing large metropolitan areas, need more urban forest management assistance than larger and more affluent communities. However, all survey respondents indicated the need for support
Crankcase sampling of PM from a fired and motored compression ignition engine
Crankcase emissions are a complex mixture of combustion products and aerosol generated from lubrication oil. The crankcase emissions contribute substantially to the total particulate matter (PM) emitted from an engine. Environment legislation demands that either the combustion and crankcase emissions are combined to give a total measurement, or the crankcase gases are re-circulated back into the engine. There is a lack of understanding regarding the physical processes that generate crankcase aerosols, with a paucity of information on the size/mass concentrations of particles present in the crankcase. In this study the particulate matter crankcase emissions were measured from a fired and motored 4 cylinder compression ignition engine at a range of speeds and crankcase locations. A sequence of sampling equipment was used to characterise the emissions in the size range 5 nm - 19 μm; Cambustion DMS500 fast particulate spectrometer, TSI Scanning Mobility Particle Sizer (SMPS), TSI™ Condensation Particle Counter (CPC) and, TSI™ Aerodynamic Particle Sizer (APS). The combination of the two test engines and range of sampling equipment provided new information on the generation and behavior of aerodynamic particulate matter within an engine crankcase. Data is presented for the effect of controlled parameter changes on number distributions over the measured particle size range. A complex lognormal bimodal size distribution of sub micron accumulation mode particles was present in the crankcase of both engines at a low idle speed of 900rpm. At 1400rpm this complex distribution was not present. Increasing the engine load, on the fired engine, initially reduced the particle number concentration with a final significant increase in particle number concentration at 75% load. At 900 rpm 50% load there was a single strong peak at 32nm in the rocker cover however sampling from the push rod gallery and sump showed a strongly bimodal distribution with peaks at 32nm and 133nm. All other sampling data, from the fired engine, was consistent at each sampling location. The SMPS results, 15-665nm, on the motored engine showed location dependency, with the highest number concentration of particles present in the push rod gallery
Herschel imaging of the dust in the Helix Nebula (NGC 7293)
In our series of papers presenting the Herschel imaging of evolved planetary
nebulae, we present images of the dust distribution in the Helix nebula (NGC
7293). Images at 70, 160, 250, 350, and 500 micron were obtained with the PACS
and SPIRE instruments on board the Herschel satellite. The broadband maps show
the dust distribution over the main Helix nebula to be clumpy and predominantly
present in the barrel wall. We determined the spectral energy distribution of
the main nebula in a consistent way using Herschel, IRAS, and Planck flux
values. The emissivity index of 0.99 +/- 0.09, in combination with the carbon
rich molecular chemistry of the nebula, indicates that the dust consists mainly
of amorphous carbon. The dust excess emission from the central star disk is
detected at 70 micron and the flux measurement agree with previous measurement.
We present the temperature and dust column density maps. The total dust mass
across the Helix nebula (without its halo) is determined to be 0.0035 solar
mass at a distance of 216 pc. The temperature map shows dust temperatures
between 22 and 42 K, which is similar to the kinetic temperature of the
molecular gas, strengthening the fact that the dust and gas co-exist in high
density clumps. Archived images are used to compare the location of the dust
emission in the far infrared (Herschel) with the ionized (GALEX, Hbeta) and
molecular hydrogen component. The different emission components are consistent
with the Helix consisting of a thick walled barrel-like structure inclined to
the line of sight. The radiation field decreases rapidly through the barrel
wall.Comment: 8 pages, 9 figures, revised version A&A in pres
Surveillance imaging of grade 1 astrocytomas in children: can duration and frequency of follow-up imaging and the use of contrast agents be reduced?
Purpose:
The optimum strategy for the surveillance of low-grade gliomas in children has not been established, and there is concern about the use of gadolinium-based contrast agents (GBCAs), particularly in children, due to their deposition in the brain. The number of surveillance scans and the use of GBCAs in surveillance of low-risk tumours should ideally be limited. We aimed to investigate the consistency and utility of our surveillance imaging and also determine to what extent the use of GBCAs contributed to decisions to escalate treatment in children with grade 1 astrocytomas. /
Methods:
This was a retrospective single-centre study at a tertiary paediatric hospital. All children with a new diagnosis of a non-syndromic World Health Organization (WHO) grade 1 astrocytoma between 2007 and 2013 were included, with surveillance imaging up to December 2018 included in analysis. The intervals of surveillance imaging were recorded, and imaging and electronic health records were examined for decisions related to treatment escalation. /
Results:
Eighty-eight patients had 690 surveillance scans in the study period. Thirty-one patients had recurrence or progression leading to treatment escalation, 30 of whom were identified on surveillance imaging. The use of GBCAs did not appear to contribute to multidisciplinary team (MDT) decisions in the majority of cases. /
Conclusion:
Surveillance imaging could be reduced in number and duration for completely resected cerebellar tumours. MDT decisions were rarely made on the basis of post-contrast imaging, and GBCA administration could therefore potentially be restricted in the setting of surveillance of grade 1 astrocytomas in children
The Electron Energy Distribution in the Hotspots of Cygnus A: Filling the Gap with the Spitzer Space Telescope
Here we present Spitzer Space Telescope imaging of Cyg A with the Infrared
Array Camera, resulting in the detection of the high-energy tails or cut-offs
in the synchrotron spectra for all four hotspots of this archetype radio
galaxy. When combined with the other data collected from the literature, our
observations allow for detailed modeling of the broad-band emission for the
brightest spots A and D. We confirm that the X-ray flux detected previously
from these features is consistent with the synchrotron self-Compton radiation
for the magnetic field intensity 170 muG in spot A, and 270 muG in spot D. We
also find that the energy density of the emitting electrons is most likely
larger by a factor of a few than the energy density of the hotspots' magnetic
field. We construct energy spectra of the radiating ultrarelativistic
electrons. We find that for both hotspots A and D these spectra are consistent
with a broken power-law extending from at least 100 MeV up to 100 GeV, and that
the spectral break corresponds almost exactly to the proton rest energy of 1
GeV. We argue that the shape of the electron continuum reflects two different
regimes of the electron acceleration process at mildly relativistic shocks,
rather than resulting from radiative cooling and/or absorption effects. In this
picture the protons' inertia defines the critical energy for the hotspot
electrons above which Fermi-type acceleration processes may play a major role,
but below which the operating acceleration mechanism has to be of a different
type. At energies >100 GeV, the electron spectra cut-off/steepen again, most
likely as a result of spectral aging due to radiative loss effects. We discuss
several implications of the presented analysis for the physics of extragalactic
jets.Comment: 29 pages, 8 figures and 2 tables included. Accepted for publication
in Ap
X-Rays from NGC 3256: High-Energy Emission in Starburst Galaxies and Their Contribution to the Cosmic X-Ray Background
The infrared-luminous galaxy NGC3256 is a classic example of a merger induced
nuclear starburst system. We find here that it is the most X-ray luminous
star-forming galaxy yet detected (~10^42 ergs/s). Long-slit optical
spectroscopy and a deep, high-resolution ROSAT X-ray image show that the
starburst is driving a "superwind" which accounts for ~20% of the observed soft
(kT~0.3 keV) X-ray emission. Our model for the broadband X-ray emission of
NGC3256 contains two additional components: a warm thermal plasma (kT~0.8 keV)
associated with the central starburst, and a hard power-law component with an
energy index of ~0.7. We find that the input of mechanical energy from the
starburst is more than sufficient to sustain the observed level of emission. We
also examine possible origins for the power-law component, concluding that
neither a buried AGN nor the expected population of high-mass X-ray binaries
can account for this emission. Inverse-Compton scattering, involving the
galaxy's copious flux of infrared photons and the relativistic electrons
produced by supernovae, is likely to make a substantial contribution to the
hard X-ray flux. Such a model is consistent with the observed radio and IR
fluxes and the radio and X-ray spectral indices. We explore the role of
X-ray-luminous starbursts in the production of the cosmic X-ray background
radiation. The number counts and spectral index distribution of the faint radio
source population, thought to be dominated by star-forming galaxies, suggest
that a significant fraction of the hard X-ray background could arise from
starbursts at moderate redshift.Comment: 31 pages (tex, epsf), 8 figures (postscript files), accepted for
publication in Part 1 of The Astrophysical Journa
Comprehensive molecular characterisation of epilepsy-associated glioneuronal tumours
Glioneuronal tumours are an important cause of treatment-resistant epilepsy. Subtypes of tumour are often poorly discriminated by histological features and may be difficult to diagnose due to a lack of robust diagnostic tools. This is illustrated by marked variability in the reported frequencies across different epilepsy surgical series. To address this, we used DNA methylation arrays and RNA sequencing to assay the methylation and expression profiles within a large cohort of glioneuronal tumours. By adopting a class discovery approach, we were able to identify two distinct groups of glioneuronal tumour, which only partially corresponded to the existing histological classification. Furthermore, by additional molecular analyses, we were able to identify pathogenic mutations in BRAF and FGFR1, specific to each group, in a high proportion of cases. Finally, by interrogating our expression data, we were able to show that each molecular group possessed expression phenotypes suggesting different cellular differentiation: astrocytic in one group and oligodendroglial in the second. Informed by this, we were able to identify CCND1, CSPG4, and PDGFRA as immunohistochemical targets which could distinguish between molecular groups. Our data suggest that the current histological classification of glioneuronal tumours does not adequately represent their underlying biology. Instead, we show that there are two molecular groups within glioneuronal tumours. The first of these displays astrocytic differentiation and is driven by BRAF mutations, while the second displays oligodendroglial differentiation and is driven by FGFR1 mutations
Implicit learning of affective responses in dementia patients: a face-emotion-association paradigm
The aim of the present study was to develop and evaluate an ecologically valid approach to assess implicit learning of affective responses in dementia patients. We designed a Face-Emotion-Association paradigm (FEA) that allows to quantify the influence of stimuli with positive and negative valence on affective responses. Two pictures of neutral male faces are rated on the dimensions of valence and arousal before and after aversive versus pleasant fictitious biographical information is paired with each of the pictures. At the second measurement time point, memory for pictures and biographical content is tested. The FEA was tested in 21 patients with dementia and 13 healthy controls. Despite severely impaired explicit memory, patients changed valence and arousal ratings according to the biographical content and did not differ in their ratings from the control group. The results demonstrate that our FEA paradigm is a valid instrument to investigate learning of affective responses in dementia patients
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