A comparison of the responses of mature and young clonal tea to drought.

To assist commercial producers with optimising the use of irrigation water, the responses to drought of mature and young tea crops (22 and 5 years after field planting respectively) were compared using data from two adjacent long-term irrigation experiments in Southern Tanzania. Providing the maximum potential soil water deficit was below about 400-500 mm for mature, and 200-250 mm for young plants (clone 6/8), annual yields of dry tea from rainfed or partially irrigated crops were similar to those from the corresponding well-watered crops. At deficits greater than this, annual yields declined rapidly in young tea (up to 22 kg (ha mm)-1) but relatively slowly in mature tea (up to 6.5 kg (ha mm)- 1). This apparent insensitivity of the mature crop to drought was due principally to compensation that occurred during the rains for yield lost in the dry season. Differences in dry matter distribution and shoot to root ratios contributed to these contrasting responses. Thus, the total above ground dry mass of well-irrigated, mature plants was about twice that for young plants. Similarly, the total mass of structural roots (>1 mm diameter), to 3 m depth, was four times greater in the mature crop than in the young crop and, for fine roots (<1 mm diameter), eight times greater. The corresponding shoot to root ratios (dry mass) were about 1:1 and 2:1 respectively. In addition, each unit area of leaf in the canopy of a mature plant had six times more fine roots (by weight) available to extract and supply water than did a young plant. Despite the logistical benefits resulting from more even crop distribution during the year when crops are fully irrigated, producers currently prefer to save water and energy costs by allowing a substantial soil water deficit to develop prior to the start of the rains, up to 250 mm in mature tea, knowing that yield compensation will occur later

Will I? won't I? Why do men who have sex with men present for post-exposure prophylaxis for sexual exposures?

Background: Failures of post-exposure prophylaxis following sexual exposure (PEPSE) to prevent seroconversion have been reported and are often associated with ongoing risk exposure. Understanding why men who have sex with men (MSM) access PEPSE on some occasions and not others may lead to more effective health promotion and disease prevention strategies Methods: A qualitative study design using semi-structured interviews of 15 MSM within 6 months of them initiating PEPSE treatment at an HIV outpatient service in Brighton, UK. Results: PEPSE seeking was motivated by a number of factors: an episode that related to a particular sexual partner and their behaviour; the characteristics of the venue where the risk occurred; the respondent’s state of mind and influences of alcohol and recreational drug use; and their perceived beliefs on the effectiveness of PEPSE. Help was sought in the light of a “one-off” or “unusual” event. Many respondents felt they were less likely to behave in a risky manner following PEPSE. Conclusion: If PEPSE is to be effective as a public health measure, at risk individuals need to be empowered to make improved risk calculations from an increased perception that they could be exposed to HIV if they continue their current behaviour patterns. The concern is that PEPSE was sought by a low number of MSM implying that a greater number are not using the service based on failure to make accurate risk calculations or recognise high-risk scenario

Technological requirements for solutions in the conservation and protection of historic monuments and archaeological remains

Executive summary: This Study has discovered many achievements associated with European support for scientific and technological research for the protection and conservation of cultural heritage. The achievements to date are: 1. Creation of an active research community 2. A body of research of unparalleled and enviable international quality and character 3. Ongoing effectiveness of research beyond initial funding 4. Substantial rate of publication 5. Imaginative tools of dissemination and publication 6. Clear spin-offs and contribution to European competitiveness often going outside the European cultural heritage area 7. Contribution to emerging European legislation, for example, air quality management. The Study has also uncovered important research gaps associated with this field that have yet to begin to be investigated. It has also discovered the need for continuing fine scale advancement in areas where researchers have been active for a number of years. The overall picture is that European research in the field of cultural heritage protection must be put on a secure footing if it is to maintain its commanding lead over other regions of the world. This Study concludes that: 1. It would be invidious to attempt to separate basic and applied research in this area of research. Like any other scientific endeavour, this field needs to integrate basic and applied research if it is to continue to thrive. 2. Small, flexible, focused interdisciplinary teams responsive to European needs, must be sustained, promoted and celebrated as models of sustainability and that what is proposed under the European Research Area (ERA) for large and complex research projects, could inflict serious damage on this area of research. 3. Resources cannot be delegated to Member States because of the interdisciplinary nature of cultural heritage and the need for a co-ordinated pan-European perspective across this research that helps to define the essential character of European cultural heritage. National programmes only serve local needs, leading to loss of strategic output, lessening of competitiveness and risk of duplication. 4. A mechanism needs to be created to help researchers working in this field to communicate and exchange information with related sectors such as construction, urban regeneration, land reclamation and agriculture. 5. There is overwhelming agreement over the need for sustainable research funding for cultural heritage and for an iterative process of exchange among researchers, decision-makers and end-users in order to maximize benefits from project inception through to dissemination, audit and review. For all the reasons mentioned above, the most significant recommendation in this Report is the identification of the need for a European Panel on the Application of Science for Cultural Heritage (EPASCH)

Crystal structure of geranylgeranyl pyrophosphate synthase (CrtE) involved in cyanobacterial terpenoid biosynthesis

Cyanobacteria are photosynthetic prokaryotes that perform oxygenic photosynthesis. Due to their ability to use the photon energy of sunlight to fix carbon dioxide into biomass, cyanobacteria are promising hosts for the sustainable production of terpenoids, also known as isoprenoids, a diverse class of natural products with potential as advanced biofuels and high-value chemicals. However, the cyanobacterial enzymes involved in the biosynthesis of the terpene precursors needed to make more complicated terpenoids are poorly characterized. Here we show that the predicted type II prenyltransferase CrtE encoded by the model cyanobacterium Synechococcus sp. PCC 7002 is homodimeric and able to synthesize C20-geranylgeranyl pyrophosphate (GGPP) from C5-isopentenyl pyrophosphate (IPP) and C5-dimethylallyl pyrophosphate (DMAPP). The crystal structure of CrtE solved to a resolution of 2.7 Å revealed a strong structural similarity to the large subunit of the heterodimeric geranylgeranyl pyrophosphate synthase 1 from Arabidopsis thaliana with each subunit containing 14 helices. Using mutagenesis, we confirmed that the fourth and fifth amino acids (Met-87 and Ser-88) before the first conserved aspartate-rich motif (FARM) play important roles in controlling chain elongation. While the WT enzyme specifically produced GGPP, variants M87F and S88Y could only generate C15-farnesyl pyrophosphate (FPP), indicating that residues with large side chains obstruct product elongation. In contrast, replacement of M87 with the smaller Ala residue allowed the formation of the longer C25-geranylfarnesyl pyrophosphate (GFPP) product. Overall, our results provide new structural and functional information on the cyanobacterial CrtE enzyme that could lead to the development of improved cyanobacterial platforms for terpenoid production

Plasmon Evolution and Charge-Density Wave Suppression in Potassium Intercalated Tantalum Diselenide

We have investigated the influence of potassium intercalation on the formation of the charge-density wave (CDW) instability in 2H-tantalum diselenide by means of Electron Energy-Loss Spectroscopy and density functional theory. Our observations are consistent with a filling of the conduction band as indicated by a substantial decrease of the plasma frequency in experiment and theory. In addition, elastic scattering clearly points to a destruction of the CDW upon intercalation as can be seen by a vanishing of the corresponding superstructures. This is accompanied by a new superstructure, which can be attributed to the intercalated potassium. Based on the behavior of the c-axis upon intercalation we argue in favor of interlayer-sites for the alkali-metal and that the lattice remains in the 2H-modification

Crystal structure of CyanoQ from the thermophilic cyanobacterium Thermosynechococcus elongatus and detection in isolated photosystem II complexes.

The PsbQ-like protein, termed CyanoQ, found in the cyanobacterium Synechocystis sp. PCC 6803 is thought to bind to the lumenal surface of photosystem II (PSII), helping to shield the Mn(4)CaO(5) oxygen-evolving cluster. CyanoQ is, however, absent from the crystal structures of PSII isolated from thermophilic cyanobacteria raising the possibility that the association of CyanoQ with PSII might not be a conserved feature. Here, we show that CyanoQ (encoded by tll2057) is indeed expressed in the thermophilic cyanobacterium Thermosynechococcus elongatus and provide evidence in support of its assignment as a lipoprotein. Using an immunochemical approach, we show that CyanoQ co-purifies with PSII and is actually present in highly pure PSII samples used to generate PSII crystals. The absence of CyanoQ in the final crystal structure is possibly due to detachment of CyanoQ during crystallisation or its presence in sub-stoichiometric amounts. In contrast, the PsbP homologue, CyanoP, is severely depleted in isolated PSII complexes. We have also determined the crystal structure of CyanoQ from T. elongatus to a resolution of 1.6 Å. It lacks bound metal ions and contains a four-helix up-down bundle similar to the ones found in Synechocystis CyanoQ and spinach PsbQ. However, the N-terminal region and extensive lysine patch that are thought to be important for binding of PsbQ to PSII are not conserved in T. elongatus CyanoQ. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1007/s11120-014-0010-z) contains supplementary material, which is available to authorized users

New Measurements of Fine-Scale CMB Polarization Power Spectra from CAPMAP at Both 40 and 90 GHz

We present new measurements of the cosmic microwave background (CMB) polarization from the final season of the Cosmic Anisotropy Polarization MAPper (CAPMAP). The data set was obtained in winter 2004-2005 with the 7 m antenna in Crawford Hill, New Jersey, from 12 W-band (84-100 GHz) and 4 Q-band (36-45 GHz) correlation polarimeters with 3.3' and 6.5' beamsizes, respectively. After selection criteria were applied, 956 (939) hours of data survived for analysis of W-band (Q-band) data. Two independent and complementary pipelines produced results in excellent agreement with each other. A broad suite of null tests as well as extensive simulations showed that systematic errors were minimal, and a comparison of the W-band and Q-band sky maps revealed no contamination from galactic foregrounds. We report the E-mode and B-mode power spectra in 7 bands in the range 200 < l < 3000, extending the range of previous measurements to higher l. The E-mode spectrum, which is detected at 11 sigma significance, is in agreement with cosmological predictions and with previous work at other frequencies and angular resolutions. The BB power spectrum provides one of the best limits to date on B-mode power at 4.8 uK^2 (95% confidence).Comment: 19 pages, 17 figures, 2 tables, submitted to Ap

Shifting a Quantum Wire through a Disordered Crystal: Observation of Conductance Fluctuations in Real Space

A quantum wire is spatially displaced by suitable electric fields with respect to the scatterers inside a semiconductor crystal. As a function of the wire position, the low-temperature resistance shows reproducible fluctuations. Their characteristic temperature scale is a few hundred millikelvin, indicating a phase-coherent effect. Each fluctuation corresponds to a single scatterer entering or leaving the wire. This way, scattering centers can be counted one by one.Comment: 4 pages, 3 figure

Ethyl cyanide on Titan: Spectroscopic detection and mapping using ALMA

We report the first spectroscopic detection of ethyl cyanide (C$_2$H$_5$CN) in Titan's atmosphere, obtained using spectrally and spatially resolved observations of multiple emission lines with the Atacama Large Millimeter/submillimeter array (ALMA). The presence of C$_2$H$_5$CN in Titan's ionosphere was previously inferred from Cassini ion mass spectrometry measurements of C$_2$H$_5$CNH$^+$. Here we report the detection of 27 rotational lines from C$_2$H$_5$CN (in 19 separate emission features detected at $>3\sigma$ confidence), in the frequency range 222-241 GHz. Simultaneous detections of multiple emission lines from HC$_3$N, CH$_3$CN and CH$_3$CCH were also obtained. In contrast to HC$_3$N, CH$_3$CN and CH$_3$CCH, which peak in Titan's northern (spring) hemisphere, the emission from C$_2$H$_5$CN is found to be concentrated in the southern (autumn) hemisphere, suggesting a distinctly different chemistry for this species, consistent with a relatively short chemical lifetime for C$_2$H$_5$CN. Radiative transfer models show that most of the C$_2$H$_5$CN is concentrated at altitudes 300-600 km, suggesting production predominantly in the mesosphere and above. Vertical column densities are found to be in the range (2-5)$\times10^{14}$ cm$^{-2}$.Comment: Published in 2015, ApJL, 800, L1