4,460 research outputs found
Banning Commercial Foresting: What are the Costs?
The Philippines' forest cover has suffered from massive denudation through the years due to uncontrolled and indiscriminate commercial logging. Because of this, calls for a total logging ban had been raised in various fora, including in the legislature where bills that consider the possibility of a ban are being studied. However, the possible economic costs of such ban as espoused in some studies has delayed the passage of these bills. This Policy Notes provides some economic costing based on computations that may help in firming up decisions regarding the proposed ban.forestry sector, environmental issues, environmental management
The transient IDEMIX model as a nonorographic gravity wave parameterization in an atmospheric circulation model
The Internal wave Dissipation, Energy and Mixing (IDEMIX) model presents a
novel way of parameterizing internal gravity waves in the atmosphere. Using a
continuous full wave spectrum in the energy balance equation and integrating
over all vertical wavenumbers and frequencies results in prognostic equations
for the energy density of gravity waves in multiple azimuthal compartments. It
includes their non-dissipative interaction with the mean flow, allowing for an
evolving and local description of momentum flux and gravity wave drag. A
saturation mechanism maintains the wave field within convective stability
limits, and an energetically consistent closure for critical-layer effects
controls how much wave flux propagates from the troposphere into the middle
atmosphere. IDEMIX can simulate zonal gravity wave drag around the mesopause,
similar to a traditional gravity wave parameterization and to a
state-of-the-art wave ray tracing model in an atmospheric circulation model. In
addition, IDEMIX shows a reversal of the gravity wave drag around the mesopause
region due to changes in the momentum flux there. When compared to empirical
model data, IDEMIX captures well the summer hemisphere flow reversal, the cold
summer mesospheric pole and the alternate positive and negative structures in
the meridional mean flow.Comment: 21 pages, 19 figure
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Studies of single top quark production at the Tevatron
In this paper we present several measurements of single top quark production from the CDF and D0 experiments at the Tevatron. The various analyses utilize integrated luminosity ranging from 2.1 to 4.8 fb{sup -1}. The results include the observation of single top production with a combined cross section of 2.76{sub -0.47}{sup +0.58} pb for a top quark mass of 170 GeV/c{sup 2}, as well as measurements of top quark polarization and first evidence for t-channel production
Novel Candidate Genes Identified in the Brain during Nociception in Common Carp (Cyprinus carpio) and Rainbow Trout (Oncorhynchus mykiss)
Recent studies have demonstrated that teleost fish possess nociceptors that detect potentially painful stimuli and that the physiological properties of these fibres are markedly similar to those found in mammals. This finding led to suggestions of possible pain perception in fish, contrary to the view that the sensory response in these animals is limited to the spinal cord and hindbrain and as such is reflexive. Therefore, the aim of this study was to determine if the brain is active at the molecular level by using a microarray analysis of gene expression in the forebrain, midbrain and hindbrain of two fish species. A comparison between the two species at different time points showed that many genes were differentially regulated in response to a noxious stimulus compared with controls. A number of genes that are involved in mammalian nociception, such as brain-derived neurotrophic factor (BDNF) and the cannabinoid CB1 receptor were regulated in the fish brain after a nociceptive event. Novel candidates that showed significant regulation in both species were also identified. In particular, the Van Gogh-like 2 gene, was regulated in both carp and trout and should be pursued to establish its precise role in nociception
Behavioural Analysis of a Nociceptive Event in Fish: Comparisons Between Three Species Demonstrate Specific Responses
Nociception is the sensory mechanism by which potentially harmful stimuli are detected in animals and humans. The behavioural responses to noxious stimulation have been studied in two fish species thus far. However, since species-specific differences are seen in mammals, more species need to be examined to determine whether nociceptive responses are generic in fish. The present study investigated the behavioural and respiratory response to an acute noxious or potentially painful stimulus in common carp (Cyprinus carpio), zebrafish (Danio rerio) and rainbow trout (Oncorhynchus mykiss). Behavioural parameters such as frequency of swimming, use of cover and any anomalous behaviour were measured along with ventilation rate before and after noxious stimulation in the carp and zebrafish. Although no differences in behavioural or ventilation rate response were observed between noxiously stimulated carp and control fish, anomalous behaviours of rocking from side to side and rubbing of lips against the tank walls were observed in two of the five fish. In contrast, zebrafish displayed a significant reduction in frequency of swimming and an increase in ventilation rate, which was similar to the results obtained from rainbow trout. Zebrafish did not display any anomalous behaviour. These dissimilarities in response to potentially painful stimulation demonstrate that there are species-specific behavioural and physiological responses to a nociceptive event in fish
The Continuing Quest for "Regolithic" Howardites
The howardite, eucrite and diogenite (HED) meteorites likely originate from asteroid 4-Vesta, the first of two asteroids targeted by NASA's Dawn mission]. Howardites are polymict breccias dominantly composed of basaltic (eucrite) and orthopyroxenitic (diogenite) material. They are believed to originate from the surface of Vesta, and may represent the regolithic surface layer. Many howardites contain "regolith"-like features including fragmental breccias clasts, carbonaceous chondrite fragments and melt clasts (impact and volcanic). Though such features may relate to asteroid regolith formation processes, the exact regolithic nature of the howardite suite is not well defined
VOFilter, Bridging Virtual Observatory and Industrial Office Applications
VOFilter is an XML based filter developed by the Chinese Virtual Observatory
project to transform tabular data files from VOTable format into OpenDocument
format. VOTable is an XML format defined for the exchange of tabular data in
the context of the Virtual Observatory (VO). It is the first Proposed
Recommendation defined by International Virtual Observatory Alliance, and has
obtained wide support from both the VO community and many Astronomy projects.
OpenOffice.org is a mature, open source, front office applications suite with
the advantage of native support of industrial standard OpenDocument XML file
format. Using the VOFilter, VOTable files can be loaded in OpenOffice.org Calc,
a spreadsheet application, and then displayed and analyzed as other spreadsheet
files. Here, the VOFilter acts as a connector, bridging the coming VO with
current industrial office applications. Virtual Observatory and technical
background of the VOFilter are introduced. Its workflow, installation and usage
are presented. Existing problems and limitations are also discussed together
with the future development plans.Comment: Accepted for publication in ChJAA (9 pages, 2 figures, 185KB
Utilization of bedside ultrasound in the diagnosis and management of massive pulmonary embolism: a case report
AbstractThe prompt diagnosis and treatment of massive pulmonary embolism is a well-known challenge for physicians. We report a case of a 61-year-old hemodynamically unstable man who presented to the emergency department with complaints of acute dyspnea. After performing a focused history and physical, we used bedside ultrasound to diagnose significant right heart strain, which suggested massive bilateral pulmonary embolisms. This diagnosis was further supported by the visualization of deep venous thrombosis in the left lower extremity. The patient was treated with IV tissue plasminogen activator in the emergency department and survived to discharge in his usual state of health
Investigation of Van Gogh-like 2 mRNA Regulation and Localisation in Response to Nociception in the Brain of Adult Common Carp (Cyprinus carpio)
The Van Gogh-like 2 (vangl2) gene is typically associated with planar cell polarity pathways, which is essential for correct orientation of epithelial cells during development. The encoded protein of this gene is a transmembrane protein and is highly conserved through evolution. Van Gogh-like 2 was selected for further study on the basis of consistent regulation after a nociceptive stimulus in adult common carp and rainbow trout in a microarray study. An in situ hybridisation was conducted in the brain of mature common carp (Cyprinus carpio), 1.5 and 3 h after a nociceptive stimulus comprising of an acetic acid injection to the lips of the fish and compared with a saline-injected control. The vangl2 gene was expressed in all brain regions, and particularly intensely in neurons of the telencephalon and in ependymal cells. In the cerebellum, a greater number (P = 0.018) of Purkinje cells expressed vangl2 after nociception (n=7) compared with controls (n = 5). This regulation opens the possibility that vangl2 is involved in nociceptive processing in the adult fish brain and may be a novel target for central nociception in vertebrates
The nature of H I absorbers in gamma-ray burst afterglows: clues from hydrodynamic simulations
In recent work, we have shown that it is possible to link quantitatively many aspects of damped Lyman α (DLA) absorbers in the spectra of quasars to high-resolution simulations of galaxy formation. Using runs from the same series of hydrodynamic numerical studies, we consider the expected properties of intrinsic Lyman α absorbers seen in the spectra of high-redshift (z > 2) gamma-ray burst afterglows (GRB–DLAs). If GRBs are associated with the death of massive stars, their afterglows provide insights into otherwise unprobed regions of protogalactic objects, but detailed physical interpretations are currently embryonic.
We find that median impact parameters (measured from the potential minimum) are approximately 1 kpc for GRBs compared with 4 kpc for quasi-stellar object–DLA (QSO–DLA). However, an equally important difference is that GRB–DLAs are predominantly associated with haloes of mass 10^(10) < M_(vir)/M_⊙ < 10^(12) , an order of magnitude larger than the hosts of QSO–DLAs. Accordingly, there are differences in the stellar properties of hosts. For instance, mean star formation rates are higher: <M(overdot)_★ ≃ 10 M_⊙ yr^(-1) for GRB–DLAs compared with <M(overdot)_★ ≃ 1 M_⊙ yr^(-1) for QSO–DLAs.
Our simulations accurately predict the form of the GRB–DLA H I column density distribution, producing quantitative agreement for N_(H I) > 10^(19) cm^(−2) , but they somewhat underpredict the incidence of low column densities N_(H I_ < 10^(19) cm^(−2) . This is reflected in our estimate of the ionizing photon escape fraction, f_(esc) ≃ 1 per cent, which is lower than the observational GRB-derived escape fraction (2 per cent). Line-of-sight neutral gas metallicities predicted by our simulations (10^(−2) < Z/Z_⊙ < 1) are consistent with the modest observational constraints. Because of large internal dispersions in gas metallicities, this agreement is not significantly compromised by imposing a cut-off on the metallicity of stars able to launch GRBs (Z_★ < Z_⊙/3) , confounding claims that the observed metallicity of GRB–DLAs poses a severe challenge to current GRB models
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