21,932 research outputs found
Seeing the trees as well as the forest: the importance of managing forest genetic resources
Reliable data on the status and trends of forest genetic resources are essential for their sustainable management. The reviews presented in this special edition of Forest Ecology and Management on forest genetic resources complement the first ever synthesis of the State of the World’s Forest Genetic Resources (SOW-FGR) that has just been published by the Food and Agriculture Organization. In this editorial, we present some of the key findings of the SOW-FGR and introduce the seven reviews presented in this special edition on: (1) tree genetic resources and livelihoods; (2) the benefits and dangers of international germplasm transfers; (3) genetic indicators for monitoring threats to populations and the effectiveness of ameliorative actions; (4) the genetic impacts of timber management practices; (5) genetic considerations in forest ecosystem restoration projects using native trees; (6) genetic-level responses to climate change; and (7) ex situ conservation approaches and their integration with in situ methods. Recommendations for action arising from the SOW-FGR, which are captured in the first Global Plan of Action for the Conservation, Sustainable Use and Development of Forest Genetic Resources, and the above articles are discussed. These include: increasing the awareness of the importance of and threats to forest genetic resources and the mainstreaming of genetic considerations into forest management and restoration; establishing common garden provenance trials to support restoration and climate change initiatives that extend to currently little-researched tree species; streamlining processes for germplasm exchange internationally for research and development; and the intelligent use of modern molecular marker methods as genetic indicators in management and for improvement purposes
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Robust and stable transcriptional repression in Giardia using CRISPRi.
Giardia lamblia is a binucleate protistan parasite causing significant diarrheal disease worldwide. An inability to target Cas9 to both nuclei, combined with the lack of nonhomologous end joining and markers for positive selection, has stalled the adaptation of CRISPR/Cas9-mediated genetic tools for this widespread parasite. CRISPR interference (CRISPRi) is a modification of the CRISPR/Cas9 system that directs catalytically inactive Cas9 (dCas9) to target loci for stable transcriptional repression. Using a Giardia nuclear localization signal to target dCas9 to both nuclei, we developed efficient and stable CRISPRi-mediated transcriptional repression of exogenous and endogenous genes in Giardia. Specifically, CRISPRi knockdown of kinesin-2a and kinesin-13 causes severe flagellar length defects that mirror defects with morpholino knockdown. Knockdown of the ventral disk MBP protein also causes severe structural defects that are highly prevalent and persist in the population more than 5 d longer than defects associated with transient morpholino-based knockdown. By expressing two guide RNAs in tandem to simultaneously knock down kinesin-13 and MBP, we created a stable dual knockdown strain with both flagellar length and disk defects. The efficiency and simplicity of CRISPRi in polyploid Giardia allows rapid evaluation of knockdown phenotypes and highlights the utility of CRISPRi for emerging model systems
Simulating Impacts of Extreme Weather Events on Urban Transport Infrastructure in the UK
Urban areas face many risks from future climate change and their infrastructure will be placed under more pressure
due to changes in climate extremes. Using the Tyndall Centre Urban Integrated Assessment Framework, this paper
describes a methodology used to assess the impacts of future climate extremes on transport infrastructure in
London. Utilising high-resolution projections for future climate in the UK, alongside stochastic weather generators
for downscaling, urban temperature and flooding models are used to provide information on the likelihood of future
extremes. These are then coupled with spatial network models of urban transport infrastructure and, using thresholds
to define the point at which systems cease to function normally, disruption to the networks can be simulated.
Results are shown for both extreme heat and urban surface water flooding events and the impacts on the travelling
population, in terms of both disruption time and monetary cost
Geometry of Empty Space is the Key to Near-Arrest Dynamics
We study several examples of kinetically constrained lattice models using
dynamically accessible volume as an order parameter. Thereby we identify two
distinct regimes exhibiting dynamical slowing, with a sharp threshold between
them. These regimes are identified both by a new response function in
dynamically available volume, as well as directly in the dynamics. Results for
the selfdiffusion constant in terms of the connected hole density are
presented, and some evidence is given for scaling in the limit of dynamical
arrest.Comment: 11 page
Multi-qubit compensation sequences
The Hamiltonian control of n qubits requires precision control of both the
strength and timing of interactions. Compensation pulses relax the precision
requirements by reducing unknown but systematic errors. Using composite pulse
techniques designed for single qubits, we show that systematic errors for n
qubit systems can be corrected to arbitrary accuracy given either two
non-commuting control Hamiltonians with identical systematic errors or one
error-free control Hamiltonian. We also examine composite pulses in the context
of quantum computers controlled by two-qubit interactions. For quantum
computers based on the XY interaction, single-qubit composite pulse sequences
naturally correct systematic errors. For quantum computers based on the
Heisenberg or exchange interaction, the composite pulse sequences reduce the
logical single-qubit gate errors but increase the errors for logical two-qubit
gates.Comment: 9 pages, 5 figures; corrected reference formattin
Sensitivity of arrest in mode-coupling glasses to low-q structure
We quantify, within mode coupling theory, how changes in the liquid structure
affect that of the glass. Apart from the known sensitivity to the structure
factor at wavevectors around the first sharp diffraction peak , we
find a strong (and inverted) response to structure at wavevectors \emph{below}
this peak: an increase in {\em lowers} the degree of arrest over a
wide -range. This strong sensitivity to `caged cage' packing effects, on
length scales of order 2d, is much weaker in attractive glasses where
short-range bonding dominates the steric caging effect.Comment: 4 pages, 5 figures. v2: 3 figures replaced; text rewritte
Closing the low-carbon material loop using a dynamic whole system approach
The transition to low carbon energy and transport systems requires an unprecedented roll-out of new infrastructure technologies, containing significant quantities of critical raw materials. Many of these technologies are based on general purpose technologies, such as permanent magnets and electric motors, that are common across different infrastructure systems. Circular economy initiatives that aim to institute better resource management practices could exploit these technological commonalities through the reuse and remanufacturing of technology components across infrastructure systems. In this paper, we analyze the implementation of such processes in the transition to low carbon electricity generation and transport on the Isle of Wight, UK. We model two scenarios relying on different renewable energy technologies, with the reuse of Lithium-ion batteries from electric vehicles for grid-attached storage. A whole-system analysis that considers both electricity and transport infrastructure demonstrates that the optimal choice of renewable technology can be dependent on opportunities for component reuse and material recycling between the different infrastructure systems. Hydrogen fuel cell based transport makes use of platinum from obsolete catalytic converters whereas lithium-ion batteries can be reused for grid-attached storage when they are no longer useful in vehicles. Trade-offs exist between the efficiency of technology reuse, which eliminates the need for new technologies for grid attached storage completely by 2033, and the higher flexibility afforded by recycling at the material level; reducing primary material demand for Lithium by 51% in 2033 compared to 30% achieved by battery reuse. This analysis demonstrates the value of a methodology that combines detailed representations of technologies and components with a systemic approach that includes multiple, interconnected infrastructure systems
Capturing the carer's experience: a researcher's reflections.
Aim To reflect on the methodological challenges of conducting a study exploring the effects on quality of life of being an informal carer for a person with palliative heart failure, as well as the factors that influence a carer's perception of caring. Background There are multi-faceted influences on the positive and negative effects of being a carer for a patient with palliative heart failure. By conducting a mixed methods study the aim was to examine and explore similarities and differences of the phenomenon of being a carer. Data sources Quantitative data obtained from the Family Quality of Life Questionnaire (FAMQOL), and qualitative data obtained from 14 interviews with informal carers of patients living with palliative heart failure. Review methods The study was conducted as part of a PhD, University of Sheffield, and the supervisory team reviewed the research process throughout the study. Discussion The study had a two-phase sequential mixed methods design. A sample of carers was recruited from heart failure nurse service caseloads in a UK urban setting. Carers were invited to complete the Family Quality of Life Questionnaire, a tool developed for carers of patients with heart failure. Participants were also asked to provide contact details if they were willing to be interviewed for the second phase of the study. Conclusion The study highlights important methodological considerations for recruiting carers. As the intention was to begin the analysis of the questionnaires before beginning the second phase of the study, the researcher was compelled to consider how integration was maintained and how to improve access to carers for research. Implications for practice The complexities associated with the population in this study led the researcher to use a pragmatic design to address research questions. When reflecting on the research and the challenges associated with recruiting to the quantitative phase of the study, the researcher used an iterative approach to meet the unfolding complexities. Such an approach could prove beneficial for mixed methods studies that aim to engage with hard to reach populations
A Socioecological Approach to Relational Demography: How Relative Representation and Respectful Coworkers Affect Job Attitudes
Purpose: This paper advances a socioecological perspective toward understanding the relationship between demography and job attitudes by considering the joint effects of individual ethnicity and ethnic group relative representation—the degree to which an individual’s own demographic group is represented similarly in their organization and the community in which the organization is located. Design/Methodology/Approach: Hierarchical polynomial regression analyses of census and survey data from 57,000 employees of 142 hospitals in the United Kingdom suggest that ethnic group relative representation is related to ethnic minority employees’ job satisfaction and turnover intentions. Findings: An asymmetric pattern emerged wherein the effect of under-representation on turnover intentions was stronger than the effect of over-representation. Moreover, the effects of relative representation varied with respectful treatment by coworkers; relative representation had little effect on attitudes of employees who reported low levels of coworker respect but generally enhanced attitudes when respect was high. Originality/Value: This work points to the meaningful role that socioecological factors can play in what are typically considered to be intraorganizational phenomena, thereby highlighting the need for organizational research to assess relevant aspects of the communities in which organizations are embedded
A search for double beta decays of tin isotopes with enhanced sensitivity
A search for the various double beta decay modes of 124Sn and 112Sn has been
performed on 75 kg.days of data. New half-life limits for excited states in
124Sn have been obtained including a lower limit for the decay into the first
excited 2+ state of 124Te of T_half > 0.87e20 yrs (90% CL) and into the first
excited 0+ state of T_half > 1.08e20 yrs (90% CL). Ground state and excited
state transitions of 112Sn have also been experimentally explored. A limit for
the 2 neutrino double electron capture of T_half > 1.8e19 yrs (90% CL) is
obtained. The non-observation of de-excitation gammas from the 0+ at 1888.5keV
results in a lower half-life limit on the 0 neutrino double electron capture
decay of 112Sn of T_half > 0.8e19 yrs (90% CL), despite a possible resonant
enhancement of the decay rate due to degenerated states.Comment: 6 pages, 7 figures, updated analysis and tex
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