353 research outputs found
Are Preserved Farms Actively Engaged in Agriculture and Conservation?
This study addresses the question of whether farms enrolled in land preservation programs are actively engaged in agricultural or conservation activities. Data are drawn from an original survey administered to preserved farm owners in the states of New Jersey, Maryland, and Delaware in 2011. âActively engagedâ is defined as investment in conservation projects, buildings, equipment, or irrigation since the land was preserved. Affirmative answers to the surveyâs investment questions range from a low of 19% for irrigation to a high of 69% for equipment. Special attention was paid to differences between lifestyle farmers and small and large commercial farmers, which are classified using the USDA typology developed in 2000. Regression analysis estimates differences in investment behavior across these groups as well as farm tenure categories, controlling for farm size, program/state location, and demographic variables. Only owners who employ tenants or managers exclusively on their land were found to invest significantly less than the largest professional farmers, and they did so across all four types of investment.
This studyâs findings support preservation goals articulated by legislators and program administrators, because (1) agricultural and land stewardship investments appear to be widespread on preserved farms, partly due to administratorsâ preference for larger parcels, (2) there is no evidence that âhobby farmersâ are disproportionately attracted to farmland preservation programs â in fact the opposite seems to be true â while those that exist in our sample behave similarly to the largest commercial farmers, (3) although tenant farming is associated in the sample with lower rates of investment, it is less common on preserved farms than on all farms in the three study states. The matter of land tenure, highlighted in this as in other studies, has not yet become a primary focus of either farm-behavioral research or state agricultural policy
Multiple timescales in a model for DNA denaturation dynamics
The denaturation dynamics of a long double-stranded DNA is studied by means
of a model of the Poland-Scheraga type. We note that the linking of the two
strands is a locally conserved quantity, hence we introduce local updates that
respect this symmetry. Linking dissipation via untwist is allowed only at the
two ends of the double strand. The result is a slow denaturation characterized
by two time scales that depend on the chain length . In a regime up to a
first characteristic time the chain embodies an
increasing number of small bubbles. Then, in a second regime, bubbles coalesce
and form entropic barriers that effectively trap residual double-stranded
segments within the chain, slowing down the relaxation to fully molten
configurations, which takes place at . This scenario is
different from the picture in which the helical constraints are neglected.Comment: 9 pages, 5 figure
Coevolved mutations reveal distinct architectures for two core proteins in the bacterial flagellar motor
Switching of bacterial flagellar rotation is caused by large domain movements of the FliG protein triggered by binding of the signal protein CheY to FliM. FliG and FliM form adjacent multi-subunit arrays within the basal body C-ring. The movements alter the interaction of the FliG C-terminal (FliGC) "torque" helix with the stator complexes. Atomic models based on the Salmonella entrovar C-ring electron microscopy reconstruction have implications for switching, but lack consensus on the relative locations of the FliG armadillo (ARM) domains (amino-terminal (FliGN), middle (FliGM) and FliGC) as well as changes during chemotaxis. The generality of the Salmonella model is challenged by the variation in motor morphology and response between species. We studied coevolved residue mutations to determine the unifying elements of switch architecture. Residue interactions, measured by their coevolution, were formalized as a network, guided by structural data. Our measurements reveal a common design with dedicated switch and motor modules. The FliM middle domain (FliMM) has extensive connectivity most simply explained by conserved intra and inter-subunit contacts. In contrast, FliG has patchy, complex architecture. Conserved structural motifs form interacting nodes in the coevolution network that wire FliMM to the FliGC C-terminal, four-helix motor module (C3-6). FliG C3-6 coevolution is organized around the torque helix, differently from other ARM domains. The nodes form separated, surface-proximal patches that are targeted by deleterious mutations as in other allosteric systems. The dominant node is formed by the EHPQ motif at the FliMMFliGM contact interface and adjacent helix residues at a central location within FliGM. The node interacts with nodes in the N-terminal FliGc α-helix triad (ARM-C) and FliGN. ARM-C, separated from C3-6 by the MFVF motif, has poor intra-network connectivity consistent with its variable orientation revealed by structural data. ARM-C could be the convertor element that provides mechanistic and species diversity.JK was supported by Medical Research Council grant U117581331. SK was supported by seed funds from Lahore University of Managment Sciences (LUMS) and the Molecular Biology Consortium
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Molecular design of the γΎT cell receptor ectodomain encodes biologically fit ligand recognition in the absence of mechanosensing
High-acuity αÎČT cell receptor (TCR) recognition of peptides bound to major histocompatibility complex molecules (pMHCs) requires mechanosensing, a process whereby piconewton (pN) bioforces exert physical load on αÎČTCRâpMHC bonds to dynamically alter their lifetimes and foster digital sensitivity cellular signaling. While mechanotransduction is operative for both αÎČTCRs and pre-TCRs within the αÎČT lineage, its role in γΎT cells is unknown. Here, we show that the human DP10.7 γΎTCR specific for the sulfoglycolipid sulfatide bound to CD1d only sustains a significant load and undergoes force-induced structural transitions when the binding interface-distal γΎ constant domain (C) module is replaced with that of αÎČ. The chimeric γΎâαÎČTCR also signals more robustly than does the wild-type (WT) γΎTCR, as revealed by RNA-sequencing (RNA-seq) analysis of TCR-transduced Rag2â/â thymocytes, consistent with structural, single-molecule, and molecular dynamics studies reflective of γΎTCRs as mediating recognition via a more canonical immunoglobulin-like receptor interaction. Absence of robust, force-related catch bonds, as well as γΎTCR structural transitions, implies that γΎT cells do not use mechanosensing for ligand recognition. This distinction is consonant with the fact that their innate-type ligands, including markers of cellular stress, are expressed at a high copy number relative to the sparse pMHC ligands of αÎČT cells arrayed on activating target cells. We posit that mechanosensing emerged over âŒ200 million years of vertebrate evolution to fulfill indispensable adaptive immune recognition requirements for pMHC in the αÎČT cell lineage that are unnecessary for the γΎT cell lineage mechanism of non-pMHC ligand detection
A 3D cellular context for the macromolecular world
We report the outcomes of the discussion initiated at the workshop entitled A 3D Cellular Context for the Macromolecular World and propose how data from emerging three-dimensional (3D) cellular imaging techniquesâsuch as electron tomography, 3D scanning electron microscopy and soft X-ray tomographyâshould be archived, curated, validated and disseminated, to enable their interpretation and reuse by the biomedical community
Observation of a kilogram-scale oscillator near its quantum ground state
We introduce a novel cooling technique capable of approaching the quantum ground state of a kilogram-scale systemâan interferometric gravitational wave detector. The detectors of the Laser Interferometer Gravitational-wave Observatory (LIGO) operate within a factor of 10 of the standard quantum limit (SQL), providing a displacement sensitivity of 10[superscript â18] m in a 100 Hz band centered on 150 Hz. With a new feedback strategy, we dynamically shift the resonant frequency of a 2.7 kg pendulum mode to lie within this optimal band, where its effective temperature falls as low as 1.4 ÎŒK, and its occupation number reaches about 200 quanta. This work shows how the exquisite sensitivity necessary to detect gravitational waves can be made available to probe the validity of quantum mechanics on an enormous mass scale.Alfred P. Sloan FoundationUnited States. National Aeronautics and Space AdministrationDavid & Lucile Packard FoundationResearch CorporationNational Science Foundation (U.S.
Association mapping of malting quality traits in UK spring and winter barley cultivar collections
Key Message: Historical malting quality data was collated from UK national and recommended list trial data and used in a GWAS. 25 QTL were identified, with the majority from spring barley cultivar sets. Abstract: In Europe, the most economically significant use of barley is the production of malt for use in the brewing and distilling industries. As such, selection for traits related to malting quality is of great commercial interest. In order to study the genetic basis of variation for malting quality traits in UK cultivars, a historical set of trial data was collated from national and recommended list trials from the period 1988 to 2016. This data was used to estimate variety means for 20 quality related traits in 451 spring barley cultivars, and 407 winter cultivars. Genotypes for these cultivars were generated using iSelect 9k and 50k genotyping platforms, and a genome wide association scan performed to identify malting quality quantitative trait loci (QTL). 24 QTL were identified in spring barley cultivars, and 2 from the winter set. A number of these correspond to known malting quality related genes but the remainder represents novel genetic variation that is accessible to breeders for the genetic improvement of new cultivars.Mark E. Looseley, Luke Ramsay, Hazel Bull, J. Stuart Swanston, Paul D. Shaw, Malcolm Macaulay, Allan Booth, Joanne R. Russell, Robbie Waugh, on behalf of the IMPROMALT Consortium, William T.B. Thoma
Agricultural Research Service Weed Science Research: Past, Present, and Future
The U.S. Department of Agriculture-Agricultural Research Service (USDA-ARS) has been a leader in weed science research covering topics ranging from the development and use of integrated weed management (IWM) tactics to basic mechanistic studies, including biotic resistance of desirable plant communities and herbicide resistance. ARS weed scientists have worked in agricultural and natural ecosystems, including agronomic and horticultural crops, pastures, forests, wild lands, aquatic habitats, wetlands, and riparian areas. Through strong partnerships with academia, state agencies, private industry, and numerous federal programs, ARS weed scientists have made contributions to discoveries in the newest fields of robotics and genetics, as well as the traditional and fundamental subjects of weed-crop competition and physiology and integration of weed control tactics and practices. Weed science at ARS is often overshadowed by other research topics; thus, few are aware of the long history of ARS weed science and its important contributions. This review is the result of a symposium held at the Weed Science Society of America\u27s 62nd Annual Meeting in 2022 that included 10 separate presentations in a virtual Weed Science Webinar Series. The overarching themes of management tactics (IWM, biological control, and automation), basic mechanisms (competition, invasive plant genetics, and herbicide resistance), and ecosystem impacts (invasive plant spread, climate change, conservation, and restoration) represent core ARS weed science research that is dynamic and efficacious and has been a significant component of the agency\u27s national and international efforts. This review highlights current studies and future directions that exemplify the science and collaborative relationships both within and outside ARS. Given the constraints of weeds and invasive plants on all aspects of food, feed, and fiber systems, there is an acknowledged need to face new challenges, including agriculture and natural resources sustainability, economic resilience and reliability, and societal health and well-being
Effects of antiplatelet therapy on stroke risk by brain imaging features of intracerebral haemorrhage and cerebral small vessel diseases: subgroup analyses of the RESTART randomised, open-label trial
Background
Findings from the RESTART trial suggest that starting antiplatelet therapy might reduce the risk of recurrent symptomatic intracerebral haemorrhage compared with avoiding antiplatelet therapy. Brain imaging features of intracerebral haemorrhage and cerebral small vessel diseases (such as cerebral microbleeds) are associated with greater risks of recurrent intracerebral haemorrhage. We did subgroup analyses of the RESTART trial to explore whether these brain imaging features modify the effects of antiplatelet therapy
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