Multi-scale analysis and validation of the Envisat MERIS Terrestrial Chlorophyll Index (MTCI) in woodland

Satellite remote sensing can be used to estimate and monitor the chlorophyll content of vegetation canopies which are a key and dynamic component of global terrestrial ecosystems. The red-edge algorithm can be used to estimate chlorophyll content from remotely sensed data but is unsuitable for use with most satellite sensor imagery. To overcome this problem, the new Envisat MERIS Terrestrial Chlorophyll index (MTCI) has been developed. It is the only operational satellite chlorophyll index and MTCI data are available as a Level 2 product from the European Space Agency. However, there is a need to ‘validate’ the MTCI over a wide range of environmental conditions. This paper reports on research that attempts to validate the MTCI using Compact Airborne Spectrographic Imager (CASI) imagery and ground data of chlorophyll content. The study site was predominantly woodland in the south of England (New Forest National Park) and had a wide range of chlorophyll contents. A transfer function derived from CASI data was used to produce a reference map of chlorophyll content, when aggregated it was compared to MERIS MTCI data and used to derive the MTCI – chlorophyll content relationship (R squared = 0.56)

Phenological trends of vegetation in Southern England From Envisat MERIS Terrestrial Chlorophyll Index (MTCI) data

Given the close association between climate change and vegetation response there is a pressing requirement to monitor the phenology of vegetation and understand how its metrics vary over space and time. This paper explores the viability of the Envisat MTCI dataset for monitoring vegetation phenology via its estimates of chlorophyll content. The MTCI was used to construct the phenological profile of and to extract key phenological dates from mixed woodland in Southern England. Woodland phenological cycles for the time period 2003 to 2007, a period with known temperature anomalies forcing variability in the phenology of the vegetation, were derived from MERIS MTCI data. Comparisons were made with ground indicators of phenology, and furthermore, crosscomparisons with other vegetation indices, namely the NDVI and EVI derived from MODIS data were conducted. Close correspondence between MTCI and canopy phenology as indicated by ground observations was evident. Also observed was a difference between MTCI-derived phenological transition curves and key transition dates and those derived from the NDVI and EVI. Overall the research presented in this paper supports the use of the Envisat MTCI for monitoring vegetation phenology, principally due to its sensitivity to canopy chlorophyll content, a vegetation property that is a useful proxy for the canopy physical and chemical alterations associated with phenological change

Oral Mutian®X stopped faecal feline coronavirus shedding by naturally infected cats

Feline coronavirus (FCoV) is common among cats living indoors in groups. In about 10% of infected cats, a potentially lethal disease, feline infectious peritonitis (FIP) occurs. Virus transmission is faecal-oral. Mutian® Xraphconn (Mutian X) is a product marketed to treat cats with FIP but is also being used to stop virus shedding, although no clear guidelines exist for its use for this purpose. The aim of this study was to establish the minimum dose and treatment duration required to ensure viral clearance from the faeces of asymptomatic virus-shedding cats. In five multicat households, 29 cats naturally infected with FCoV and actively shedding virus in the faeces were given Mutian X pills. Virus shedding was monitored using reverse-transcription quantitative polymerase chain reaction (RT-qPCR) controlled for faecal inhibitors to ensure sensitivity. Mutian X given orally cleared the virus in 29 cats; although four cats required a repeated course to finally stop virus shedding. A dose of 4 mg/kg q24 h for four days was found to be the optimal treatment protocol: 2 mg/kg cleared only 80% of cats. Post-treatment using a sensitive RT-qPCR test was essential to ensure that virus clearance had been achieved, since failure to clear even one cat can result in re-infection of the others. Records of virus shedding by cats before treatment provided a retrospective control: significantly more cats stopped shedding virus after Mutian X than recovered from infection during the control period (p < .00001). This is the first report of the successful elimination of faecal FCoV shedding in chronically infected cats

A Comprehensive Analysis of Swift/XRT Data: III. Jet Break Candidates in X-ray and Optical Afterglow Lightcurves

The Swift/XRT data of 179 GRBs (from 050124 to 070129) and the optical afterglow data of 57 pre- and post-Swift GRBs are analyzed, in order to systematically investigate the jet-like breaks in the X-ray and optical afterglow lightcurves. We find that not a single burst can be included in the ``Platinum'' sample, in which the data satisfy all the criteria of a jet break. By releasing one or more requirements to define a jet break, some candidates of various degrees could be identified. In the X-ray band, 42 out of the 103 well-sampled X-ray lightcurves have a decay slope of the post-break segment >1.5 (``Bronze'' sample), and 27 of them also satisfy the closure relations of the forward models (``Silver'' sample). The numbers of the ``Bronze'' and ``Silver'' candidates in the optical lightcurves are 27 and 23, respectively. Thirteen bursts have well-sampled optical and X-ray lightcurves, but only seven cases are consistent with an achromatic break, but even in these cases only one band satisfies the closure relations (``Gold'' sample). The observed break time in the XRT lightcurves is systematically earlier than that in the optical bands. All these raise great concerns in interpreting the jet-like breaks as jet breaks and further inferring GRB energetics from these breaks. By assuming that these breaks are jet breaks, we perform a similar analysis as previous work to calculate the jet opening angle (theta_j) and energetics (E_k) with the ``Silver'' and ``Gold'' jet break candidates. The derived E_K distribution reveals a much larger scatter than the pre-Swift sample. A tentative anti-correlation between theta_j and E_{K,iso} is found for both the pre-Swift and Swift GRBs, indicating that the E_K could still be quasi-universal, if the breaks in discussion are indeed jet breaks(abridge).Comment: 48 pages, including 5 tables and 8 figures. Accepted for publication in ApJ. This is the third paper of a series. Paper I and II see astro-ph/0612246 (ApJ, 2007, 666,1002) and arXiv:0705.1373 (ApJ, 2007, 669, n2,in press

Engineered polyketides: Synergy between protein and host level engineering

Metabolic engineering efforts toward rewiring metabolism of cells to produce new compounds often require the utilization of non-native enzymatic machinery that is capable of producing a broad range of chemical functionalities. Polyketides encompass one of the largest classes of chemically diverse natural products. With thousands of known polyketides, modular polyketide synthases (PKSs) share a particularly attractive biosynthetic logic for generating chemical diversity. The engineering of modular PKSs could open access to the deliberate production of both existing and novel compounds. In this review, we discuss PKS engineering efforts applied at both the protein and cellular level for the generation of a diverse range of chemical structures, and we examine future applications of PKSs in the production of medicines, fuels and other industrially relevant chemicals

Effectiveness of common household cleaning agents in reducing the viability of human influenza A/H1N1

In the event of an influenza pandemic, the majority of people infected will be nursed at home. It is therefore important to determine simple methods for limiting the spread of the virus within the home. The purpose of this work was to test a representative range of common household cleaning agents for their effectiveness at killing or reducing the viability of influenza A virus

Acceptability of HIV Testing Sites Among Rural and Urban African Americans Who Use Cocaine

African Americans (AAs) who use cocaine in the Southern region of the U.S. have a relatively high risk of HIV and need for HIV testing. Among this group, those residing in rural areas may have less favorable opinions about common HIV testing sites, which could inhibit HIV testing. We examined rural/urban variations in their acceptability of multiple HIV testing sites (private physician clinic, local health department, community health center, community HIV fair, hospital emergency department, blood plasma donation center, drug abuse treatment facility, and mobile van or community outreach worker). Results from partial proportional odds and logistic regression analyses indicate that rural AA who use cocaine have lower odds of viewing local health departments (OR = 0.09, 95 % CI = 0.03–0.21), physician offices (OR = 0.19, 95 % CI = 0.09–0.42), and drug use treatment centers (OR = 0.49; 95 % CI = 0.30–0.80) as acceptable relative to their urban counterparts. The findings have implications for further targeting HIV testing toward AAs who use of cocaine, particularly those residing in the rural South

Electron-impact ionization of atomic hydrogen at 2 eV above threshold

The convergent close-coupling method is applied to the calculation of fully differential cross sections for ionization of atomic hydrogen by 15.6 eV electrons. We find that even at this low energy the method is able to yield predictive results with small uncertainty. As a consequence we suspect that the experimental normalization at this energy is approximately a factor of two too high.Comment: 10 page

Quantum Symmetries and Strong Haagerup Inequalities

In this paper, we consider families of operators $\{x_r\}_{r \in \Lambda}$ in a tracial C$^\ast$-probability space $(\mathcal A, \phi)$, whose joint $\ast$-distribution is invariant under free complexification and the action of the hyperoctahedral quantum groups $\{H_n^+\}_{n \in \N}$. We prove a strong form of Haagerup's inequality for the non-self-adjoint operator algebra $\mathcal B$ generated by $\{x_r\}_{r \in \Lambda}$, which generalizes the strong Haagerup inequalities for $\ast$-free R-diagonal families obtained by Kemp-Speicher \cite{KeSp}. As an application of our result, we show that $\mathcal B$ always has the metric approximation property (MAP). We also apply our techniques to study the reduced C$^\ast$-algebra of the free unitary quantum group $U_n^+$. We show that the non-self-adjoint subalgebra $\mathcal B_n$ generated by the matrix elements of the fundamental corepresentation of $U_n^+$ has the MAP. Additionally, we prove a strong Haagerup inequality for $\mathcal B_n$, which improves on the estimates given by Vergnioux's property RD \cite{Ve}

Resolving the complex structure of the dust torus in the active nucleus of the Circinus galaxy

To test the dust torus model for active galactic nuclei directly, we study the extent and morphology of the nuclear dust distribution in the Circinus galaxy using high resolution interferometric observations in the mid-infrared with the MIDI instrument at the Very Large Telescope Interferometer. We find that the dust distribution in the nucleus of Circinus can be explained by two components, a dense and warm disk-like component of 0.4 pc size and a slightly cooler, geometrically thick torus component with a size of 2.0 pc. The disk component is oriented perpendicular to the ionisation cone and outflow and seems to show the silicate feature at 10 micron in emission. It coincides with a nuclear maser disk in orientation and size. From the energy needed to heat the dust, we infer a luminosity of the accretion disk corresponding to 20% of the Eddington luminosity of the nuclear black hole. We find that the interferometric data are inconsistent with a simple, smooth and axisymmetric dust emission. The irregular behaviour of the visibilities and the shallow decrease of the dust temperature with radius provide strong evidence for a clumpy or filamentary dust structure. We see no evidence for dust reprocessing, as the silicate absorption profile is consistent with that of standard galactic dust. We argue that the collimation of the ionising radiation must originate in the geometrically thick torus component. Our findings confirm the presence of a geometrically thick, torus-like dust distribution in the nucleus of Circinus, as required in unified schemes of Seyfert galaxies. Several aspects of our data require that this torus is irregular, or "clumpy".Comment: 20 pages, 16 figures, accepted for publication by A&