1,360 research outputs found
An assessment of the use of crown structure for the determination of the health of beech (Fagus sylvatica)
Considerable difficulties exist with the standardization and interpretation of assessments of crown defoliation, the most commonly used index of tree health in Europe. A variety of other measures of crown condition exist and one that has received considerable attention, particularly for beech (Fagus sylvatica L.), is crown architecture. Four stages of crown development are generally recognized, termed the exploration, degeneration, stagnation and resignation phases. An analysis of the available literature suggests that there are a number of problems surrounding the use of these classes to describe trees. Although the classes probably reflect the progressive deterioration of the crown of a tree, there are many factors that affect the assessment and interpretation of the scores, as is the case for defoliation estimates. Measurements of shoot elongation in the upper crown provide a more useful measure, but involve destructive sampling and are very time-consuming. Consequently, while crown architectural assessments should only be incorporated into large-scale inventories of forest health with great care, they may be useful for case studies involving the detailed examination of a small number of site
Dental Involvements in the Equine
On February 27, 1945, a 4-year-old mare was presented to the Stange Memorial Clinic. A swelling on the right side of the face had been noted the previous day. The tongue was swollen and she was unable to open her mouth. The temperature was normal and the general condition good
Madagascar rosewood, illegal logging and the tropical timber trade
Although deforestation rates in the tropics are reportedly slowing, the loss of both forest area and forest quality remains a significant issue for many countries. This is particularly true of Madagascar, where recent government instability has enabled a significant increase in the incidence of illegal logging of Dalbergia species from National Parks such as Marojejy and Masoala. The logs are exported with relative ease as export permits are being made available. While attempts have been made to improve the management of tropical forests, in 2005, the International Tropical Timber Organization considered that only 7% of tropical production forests were being managed sustainably. Given the challenges associated with halting illegal logging at source, emphasis has shifted to the control of the trade in forest products. The Convention on the Internationa Trade in Endangered Species provides a mechanism to restrict such trade, but the Madagascan Dalbergia species are not listed. In the USA, the recent amendments to the âLacey Actâ could provide a significant disincentive to the import of illegally logged wood products, but it remains to be seen whether this Act can be enforced effectively.RĂSUMĂBien que les taux de dĂ©boisement sous les tropiques seraient Ă la basse, il nâen demeure pas moins que la perte de la couverture forestiĂšre et de la qualitĂ© des forĂȘts restent des sujets sensibles pour de nombreux pays. Cela sâest avĂ©rĂ© dâautant plus vrai Ă Madagascar que de rĂ©cents troubles politiques ont Ă©tĂ© accompagnĂ©s par une augmentation significative de lâexploitation illicite de bois prĂ©cieux, dont les bois de rose et les palissandres (Dalbergia spp.) dans les parcs nationaux comme ceux de Marojejy ou de Masoala. Les bois sont exportĂ©s assez facilement avec la dĂ©livrance de permis dâexportation dans un cadre lĂ©gislatif changeant. Dans le monde, il y a bien eu des essais dâamĂ©lioration de la gestion des forĂȘts tropicales mais en 2005, lâOrganisation internationale des bois tropicaux considĂ©rait que seulement 7% des produits sylvicoles issus des forĂȘts tropicales Ă©taient exploitĂ©s de maniĂšre pĂ©renne. Compte tenu de la difficultĂ© Ă sâattaquer aux sources de lâexploitation illĂ©gale pour y mettre un terme, une attention particuliĂšre a Ă©tĂ© portĂ©e sur le contrĂŽle du commerce des produits forestiers. La convention sur le commerce international des espĂšces de faune et de flore sauvages menacĂ©es dâextinction connue par son sigle CITES constitue un mĂ©canisme permettant de limiter un tel commerce mais les espĂšces malgaches du genre Dalbergia pour les bois de rose et les palissandres ou Diospyros pour les Ă©bĂšnes ne figurent pas sur les listes de la CITES. Aux Ătats - Unis, le nouvel amendement au âLacey Actâ pourrait permettre de freiner de maniĂšre significative lâimportation de produits forestiers exploitĂ©s illĂ©galement mais il faut voir si cette Loi pourra effectivement ĂȘtre imposĂ©e
Dynamical Masses for Low-Mass Pre-Main Sequence Stars: A Preliminary Physical Orbit for HD 98800 B
We report on Keck Interferometer observations of the double-lined binary (B)
component of the quadruple pre-main sequence (PMS) system HD 98800. With these
interferometric observations combined with astrometric measurements made by the
Hubble Space Telescope Fine Guidance Sensors (FGS), and published radial
velocity observations we have estimated preliminary visual and physical orbits
of the HD 98800 B subsystem. Our orbit model calls for an inclination of 66.8
3.2 deg, and allows us to infer the masses and luminosities of the
individual components. In particular we find component masses of 0.699
0.064 and 0.582 0.051 M_{\sun} for the Ba (primary) and Bb (secondary)
components respectively.
Modeling of the component SEDs finds temperatures and luminosities in
agreement with previous studies, and coupled with the component mass estimates
allows for comparison with PMS models in the low-mass regime with few empirical
constraints. Solar abundance models seem to under-predict the inferred
component temperatures and luminosities, while assuming slightly sub-solar
abundances bring the models and observations into better agreement. The present
preliminary orbit does not yet place significant constraints on existing
pre-main sequence stellar models, but prospects for additional observations
improving the orbit model and component parameters are very good.Comment: 20 pages, 6 figures, ApJ in press; tables 2 and 3 to be included in
ApJ versio
Discoveries from a Near-infrared Proper Motion Survey using Multi-epoch 2MASS Data
We have conducted a 4030-square-deg near-infrared proper motion survey using
multi-epoch data from the Two Micron All-Sky Survey (2MASS). We find 2778
proper motion candidates, 647 of which are not listed in SIMBAD. After
comparison to DSS images, we find that 107 of our proper motion candidates lack
counterparts at B-, R-, and I-bands and are thus 2MASS-only detections. We
present results of spectroscopic follow-up of 188 targets that include the
infrared-only sources along with selected optical-counterpart sources with
faint reduced proper motions or interesting colors. We also establish a set of
near-infrared spectroscopic standards with which to anchor near-infrared
classifications for our objects. Among the discoveries are six young field
brown dwarfs, five "red L" dwarfs, three L-type subdwarfs, twelve M-type
subdwarfs, eight "blue L" dwarfs, and several T dwarfs. We further refine the
definitions of these exotic classes to aid future identification of similar
objects. We examine their kinematics and find that both the "blue L" and "red
L" dwarfs appear to be drawn from a relatively old population. This survey
provides a glimpse of the kinds of research that will be possible through
time-domain infrared projects such as the UKIDSS Large Area Survey, various
VISTA surveys, and WISE, and also through z- or y-band enabled, multi-epoch
surveys such as Pan-STARRS and LSST.Comment: To appear in the September 2010 issue of The Astrophysical Journal,
Supplement Serie
Chandra Observation of V426 Oph: Weighing the Evidence for a Magnetic White Dwarf
We report the results of a 45 ks Chandra observation of the cataclysmic
variable V426 Ophiuchus. The high resolution spectrum from the high-energy
transmission grating spectrometer is most consistent with a cooling flow model,
placing V426 Oph among the group of CVs including U Gem and EX Hya. An
uninterrupted lightcurve was also constructed, in which we detect a significant
4.2 hr modulation together with its first harmonic at 2.1 hrs. Reanalysis of
archival Ginga, and ROSAT X-ray lightcurves also reveals modulations at periods
consistent with 4.2 and/or 2.1 hrs. Furthermore, optical photometry in V,
simultaneous with the Chandra observation, indicates a modulation
anti-correlated with the X-ray, and later more extensive R band photometry
finds a signal at ~2.1 hrs. The earlier reported X-ray periods at ~0.5 and 1
hrs appear to be only transient and quasi-periodic in nature. In contrast, the
4.2 hr period or its harmonic are stable and persistent in X-ray/optical data
from 1988 to 2003. This periodicity is clearly distinct from the 6.85 hr orbit,
and could be due to the spin of the white dwarf. If this is the case, V426 Oph
would be the first long period intermediate polar with a ratio P_spin/P_orb of
0.6. However, this interpretation requires unreasonable values of magnetic
field strength and mass accretion rate.Comment: 11 pages, 7 figures, 5 tables. Accepted for publication in the
Astrophysical Journal (to appear August 2004
"It's really no more difficult than putting on fluoride varnish":a qualitative exploration of dental professionals' views of silver diamine fluoride for the management of carious lesions in children
Background
Despite evidence that Silver Diamine Fluoride (SDF) can be effective in managing carious lesions in primary teeth, the use of SDF in the UK remains limited. This study explored dental professionalsâ views and experiences of using SDF for managing carious lesions in children. In addition, it explored what they perceived to be the advantages, disadvantages, barriers and enablers to the use of SDF in practice.
Methods
Fifteen semi-structured face-to-face or over-the-phone interviews were conducted with 14 dental professionals from NHS Tayside and NHS Grampian in Scotland. Interviews were transcribed verbatim, coded and analysed using a thematic approach.
Results
Thirteen of 14 dental professionals interviewed were familiar with, or had some existing knowledge of, SDF. Four had used it to treat patients. The majority of participants thought that the main advantage of SDF was that it required minimal patient cooperation. SDF was also perceived as a simple, pain-free and non-invasive treatment approach that could help acclimatise children to the dental environment. However, SDF-induced black staining of arrested carious lesions was most commonly reported as the main disadvantage and greatest barrier to using it in practice. Participants believed that this discolouration would concern some parents who may fear that the black appearance may instigate bullying at school and that others may judge parents as neglecting their childâs oral health. Participants thought that education of clinicians about SDF use and information sheets for parents would enhance the uptake of SDF in dental practice. Participants believed that younger children might not be as bothered by the discolouration as older ones and they anticipated greater acceptance of SDF for posterior primary teeth by both parents and children.
Conclusion
Dental professionals were aware that SDF can be used for arresting carious lesions. They pointed out that the staining effect of carious lesions is a major disadvantage that could be a barrier for many parents. Participants considered the application process to be simple and non-invasive and requires a minimum level of child cooperation. Participants appreciated the potential of SDF in paediatric dentistry and suggested actions that could help overcome the barriers they highlighted
LEMUR: Large European Module for solar Ultraviolet Research. European contribution to JAXA's Solar-C mission
Understanding the solar outer atmosphere requires concerted, simultaneous
solar observations from the visible to the vacuum ultraviolet (VUV) and soft
X-rays, at high spatial resolution (between 0.1" and 0.3"), at high temporal
resolution (on the order of 10 s, i.e., the time scale of chromospheric
dynamics), with a wide temperature coverage (0.01 MK to 20 MK, from the
chromosphere to the flaring corona), and the capability of measuring magnetic
fields through spectropolarimetry at visible and near-infrared wavelengths.
Simultaneous spectroscopic measurements sampling the entire temperature range
are particularly important.
These requirements are fulfilled by the Japanese Solar-C mission (Plan B),
composed of a spacecraft in a geosynchronous orbit with a payload providing a
significant improvement of imaging and spectropolarimetric capabilities in the
UV, visible, and near-infrared with respect to what is available today and
foreseen in the near future.
The Large European Module for solar Ultraviolet Research (LEMUR), described
in this paper, is a large VUV telescope feeding a scientific payload of
high-resolution imaging spectrographs and cameras. LEMUR consists of two major
components: a VUV solar telescope with a 30 cm diameter mirror and a focal
length of 3.6 m, and a focal-plane package composed of VUV spectrometers
covering six carefully chosen wavelength ranges between 17 and 127 nm. The
LEMUR slit covers 280" on the Sun with 0.14" per pixel sampling. In addition,
LEMUR is capable of measuring mass flows velocities (line shifts) down to 2
km/s or better.
LEMUR has been proposed to ESA as the European contribution to the Solar C
mission.Comment: 35 pages, 14 figures. To appear on Experimental Astronom
Evidence for HIV-1 cure after CCR5 Î32/Î32 allogeneic haemopoietic stem-cell transplantation 30 months post analytical treatment interruption : a case report
The London patient (participant 36 in the IciStem cohort) underwent allogeneic stem-cell transplantation with cells that did not express CCR5 (CCR5 Î32/Î32); remission was reported at 18 months after analytical treatment interruption (ATI). Here, we present longer term data for this patient (up to 30 months after ATI), including sampling from diverse HIV-1 reservoir sites. We used ultrasensitive viral load assays of plasma, semen, and cerebrospinal fluid (CSF) samples to detect HIV-1 RNA. In gut biopsy samples and lymph-node tissue, cell-copy number and total HIV-1 DNA levels were quantified in multiple replicates, using droplet digital PCR (ddPCR) and quantitative real-time PCR. We also analysed the presence of intact proviral DNA using multiplex ddPCR targeting the packaging signal (Ï) and envelope (env). We did intracellular cytokine staining to measure HIV-1-specific T-cell responses. We used low-sensitive and low-avidity antibody assays to measure the humoral response to HIV-1. We predicted the probability of rebound using a mathematical model and inference approach. HIV-1 viral load in plasma remained undetectable in the London patient up to 30 months (last tested on March 4, 2020), using an assay with a detection limit of 1 copy per mL. The patient's CD4 count was 430 cells per ÎŒL (23·5% of total T cells) at 28 months. A very low-level positive signal for HIV-1 DNA was recorded in peripheral CD4 memory cells at 28 months. The viral load in semen was undetectable in both plasma (lower limit of detection [LLD] <12 copies per mL) and cells (LLD 10 copies per 10 6 cells) at 21 months. CSF was within normal parameters at 25 months, with HIV-1 RNA below the detection limit (LLD 1 copy per mL). HIV-1 DNA by ddPCR was negative in rectum, caecum, and sigmoid colon and terminal ileum tissue samples at 22 months. Lymph-node tissue from axilla was positive for the long-terminal repeat (33 copies per 10 6 cells) and env (26·1 copies per 10 6 cells), negative for Ï and integrase, and negative by the intact proviral DNA assay, at 27 months. HIV-1-specific CD4 and CD8 T-cell responses have remained absent at 27 months. Low-avidity Env antibodies have continued to decline. Mathematical modelling suggests that the probability of remission for life (cure) is 98% in the context of 80% donor chimerism in total HIV target cells and greater than 99% probability of remission for life with 90% donor chimerism. The London patient has been in HIV-1 remission for 30 months with no detectable replication-competent virus in blood, CSF, intestinal tissue, or lymphoid tissue. Donor chimerism has been maintained at 99% in peripheral T cells. We propose that these findings represent HIV-1 cure. Wellcome Trust and amfAR (American Foundation for AIDS Research)
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