482 research outputs found
Transitioning out of Open Access: A Closer Look at Institutions for Management of Groundwater Rights in France, California, and Spain
[EN] Many regions around the world are transitioning out of open access to groundwater resources in order to tackle over extraction by irrigated agriculture. However, the state has limited capacities to regulate effectively agricultural groundwater use. This paper evaluates how users and public authorities can co-manage groundwater extraction by agriculture. Based on Schlager and Ostrom¿s ¿bundle of rights¿ framework, the paper examines how decisions over access and use of groundwater resources are made in France, Spain and California. The three cases share a common strive to involve groundwater users in decisions over how to reduce over extraction of groundwater resources. However, different choices were made regarding the institutional set-up for user involvement in allocation decisions. The paper presents the diversity of institutional arrangements influencing groundwater allocations in the three cases, and the relative involvement and power of users and public authorities over these institutions.
The papers show the different ways in which ¿comanagement¿ may be made operational for managing agricultural groundwater use.This research benefited from funding of the EU H2020 RURECO project (grant agreement 750553) and from Montpellier University I-Site MUSE. This study has also received funding from the eGROUNDWATER project (GA n. 1921), part of the PRIMA programme supported by the European Union's Horizon 2020 research and innovation programmeRouillard, J.; Babbitt, C.; Pulido-Velazquez, M.; Rinaudo, J. (2021). Transitioning out of Open Access: A Closer Look at Institutions for Management of Groundwater Rights in France, California, and Spain. Water Resources Research. 57(4):1-20. https://doi.org/10.1029/2020WR028951S12057
Diagonalization of an Integrable Discretization of the Repulsive Delta Bose Gas on the Circle
We introduce an integrable lattice discretization of the quantum system of n
bosonic particles on a ring interacting pairwise via repulsive delta
potentials. The corresponding (finite-dimensional) spectral problem of the
integrable lattice model is solved by means of the Bethe Ansatz method. The
resulting eigenfunctions turn out to be given by specializations of the
Hall-Littlewood polynomials. In the continuum limit the solution of the
repulsive delta Bose gas due to Lieb and Liniger is recovered, including the
orthogonality of the Bethe wave functions first proved by Dorlas (extending
previous work of C.N. Yang and C.P. Yang).Comment: 25 pages, LaTe
Multi-Magnon Scattering in the Ferromagnetic XXX-Model with Inhomogeneities
We determine the transition amplitude for multi-magnon scattering induced
through an inhomogeneous distribution of the coupling constant in the
ferromagnetic XXX-model. The two and three particle amplitudes are explicitely
calculated at small momenta. This suggests a rather plausible conjecture also
for a formula of the general n-particle amplitude.Comment: 21 pages, latex, no figure
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The effects of weight loss and salt reduction on visit-to-visit blood pressure variability: results from a multicenter randomized controlled trial
Objectives: As evidence suggests visit-to-visit variability (VVV) of blood pressure (BP) is associated with cardiovascular events and mortality, there is increasing interest in identifying interventions that reduce VVV of BP. We investigated the effects of weight loss and sodium reduction, alone or in combination, on VVV of BP in participants enrolled in phase II of the Trials of Hypertension Prevention. Methods: BP readings were taken at 6-month intervals for 36 months in 1820 participants with high-normal DBP who were randomized to weight loss, sodium reduction, combination (weight loss and sodium reduction), or usual care groups. VVV of BP was defined as the SD of BP across six follow-up visits. Results: VVV of SBP was not significantly different between participants randomized to the weight loss (7.2 ± 3.1 mmHg), sodium reduction (7.1 ± 3.0 mmHg), or combined (6.9 ± 2.9 mmHg) intervention groups vs. the usual care group (6.9 ± 2.9 mmHg). In a fully adjusted model, no difference (0.0 ± 0.2 mmHg) in VVV of SBP was present between individuals who successfully maintained their weight loss vs. individuals who did not lose weight during follow-up (P = 0.93). Also, those who maintained a reduced sodium intake throughout follow-up did not have lower VVV of SBP compared to those who did not reduce their sodium intake (0.1 ± 0.3 mmHg; P = 0.77). Results were similar for VVV of DBP. Conclusions: These findings suggest that weight loss and sodium reduction may not be effective interventions for lowering VVV of BP in individuals with high-normal DBP
PNAS plus: plasmodium falciparum responds to amino acid starvation by entering into a hibernatory state
The human malaria parasite Plasmodium falciparum is auxotrophic for most amino acids. Its amino acid needs are met largely through the degradation of host erythrocyte hemoglobin; however the parasite must acquire isoleucine exogenously, because this amino acid is not present in adult human hemoglobin. We report that when isoleucine is withdrawn from the culture medium of intraerythrocytic P. falciparum, the parasite slows its metabolism and progresses through its developmental cycle at a reduced rate. Isoleucine-starved parasites remain viable for 72 h and resume rapid growth upon resupplementation. Protein degradation during starvation is important for maintenance of this hibernatory state. Microarray analysis of starved parasites revealed a 60% decrease in the rate of progression through the normal transcriptional program but no other apparent stress response. Plasmodium parasites do not possess a TOR nutrient-sensing pathway and have only a rudimentary amino acid starvation-sensing eukaryotic initiation factor 2α (eIF2α) stress response. Isoleucine deprivation results in GCN2-mediated phosphorylation of eIF2α, but kinase-knockout clones still are able to hibernate and recover, indicating that this pathway does not directly promote survival during isoleucine starvation. We conclude that P. falciparum, in the absence of canonical eukaryotic nutrient stress-response pathways, can cope with an inconsistent bloodstream amino acid supply by hibernating and waiting for more nutrient to be provided
Tempo and mode of gene expression evolution in the brain across primates
Primate evolution has led to a remarkable diversity of behavioral specializations and pronounced brain size variation among species (Barton, 2012; DeCasien and Higham, 2019; Powell et al., 2017). Gene expression provides a promising opportunity for studying the molecular basis of brain evolution, but it has been explored in very few primate species to date (e.g. Khaitovich et al., 2005; Khrameeva et al., 2020; Ma et al., 2022; Somel et al., 2009). To understand the landscape of gene expression evolution across the primate lineage, we generated and analyzed RNA-seq data from four brain regions in an unprecedented eighteen species. Here, we show a remarkable level of variation in gene expression among hominid species, including humans and chimpanzees, despite their relatively recent divergence time from other primates. We found that individual genes display a wide range of expression dynamics across evolutionary time reflective of the diverse selection pressures acting on genes within primate brain tissue. Using our samples that represent a 190-fold difference in primate brain size, we identified genes with variation in expression most correlated with brain size. Our study extensively broadens the phylogenetic context of what is known about the molecular evolution of the brain across primates and identifies novel candidate genes for the study of genetic regulation of brain evolution
Endothelial Activation Microparticles and Inflammation Status Improve with Exercise Training in African Americans
African Americans have the highest prevalence of hypertension in the world which may emanate from their predisposition to heightened endothelial inflammation. The purpose of this study was to determine the effects of a 6-month aerobic exercise training (AEXT) intervention on the inflammatory biomarkers interleukin-10 (IL-10), interleukin-6 (IL-6), and endothelial microparticle (EMP) CD62E+ and endothelial function assessed by flow-mediated dilation (FMD) in African Americans. A secondary purpose was to evaluate whether changes in IL-10, IL-6, or CD62E+ EMPs predicted the change in FMD following the 6-month AEXT intervention. A pre-post design was employed with baseline evaluation including office blood pressure, FMD, fasting blood sampling, and graded exercise testing. Participants engaged in 6 months of AEXT. Following the AEXT intervention, all baseline tests were repeated. FMD significantly increased, CD62E+ EMPs and IL-6 significantly decreased, and IL-10 increased but not significantly following AEXT. Changes in inflammatory biomarkers did not significantly predict the change in FMD. The change in significantly predicted the change in IL-10. Based on these results, AEXT may be a viable, nonpharmacological method to improve inflammation status and endothelial function and thereby contribute to risk reduction for cardiovascular disease in African Americans
A Conditional Yeast E1 Mutant Blocks the Ubiquitin–Proteasome Pathway and Reveals a Role for Ubiquitin Conjugates in Targeting Rad23 to the Proteasome
E1 ubiquitin activating enzyme catalyzes the initial step in all ubiquitin-dependent processes. We report the isolation of uba1-204, a temperature-sensitive allele of the essential Saccharomyces cerevisiae E1 gene, UBA1. Uba1-204 cells exhibit dramatic inhibition of the ubiquitin–proteasome system, resulting in rapid depletion of cellular ubiquitin conjugates and stabilization of multiple substrates. We have employed the tight phenotype of this mutant to investigate the role ubiquitin conjugates play in the dynamic interaction of the UbL/UBA adaptor proteins Rad23 and Dsk2 with the proteasome. Although proteasomes purified from mutant cells are intact and proteolytically active, they are depleted of ubiquitin conjugates, Rad23, and Dsk2. Binding of Rad23 to these proteasomes in vitro is enhanced by addition of either free or substrate-linked ubiquitin chains. Moreover, association of Rad23 with proteasomes in mutant and wild-type cells is improved upon stabilizing ubiquitin conjugates with proteasome inhibitor. We propose that recognition of polyubiquitin chains by Rad23 promotes its shuttling to the proteasome in vivo
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Effects of Moderate Aerobic Exercise Training on Vascular Health and Blood Pressure in African Americans
As healthcare progresses toward individualized medicine, understanding how different racial groups respond to lifestyle interventions is valuable. It is established that African Americans have disproportionate levels of cardiovascular disease and impaired vascular health, and clinical practice guidelines suggest lifestyle interventions as the first line of treatment. Recently, the authors reported that 6 months of aerobic exercise improved inflammatory markers, flow-mediated dilation (FMD), and levels of circulating endothelial microparticles (EMPs) in African American adults. This study is a subgroup analysis of the aerobic exercise–induced changes in vascular health and blood pressure (BP) measures, including carotid artery intima-media thickness (IMT), nitroglycerin-mediated dilation (NMD), ambulatory BP, and office BP. Sedentary African American adults (53.4±6.2 years; 21 women and 5 men) showed improved vascular health but no change in BP. Carotid artery IMT decreased 6.4%, plasma nitric oxide levels increased 76.6%, plasma EMP levels decreased, percentage of FMD increased 59.6%, and FMD/NMD ratio increased 36.2% (P<.05 for all). Six months of aerobic exercise training is sufficient to elicit improvements in vascular structure and function in African Americans, even without improvements in BP measures or NMD (ie, smooth muscle function). To our knowledge, this is the first study to report such findings in African Americans
Evolutionarily Conserved Substrate Substructures for Automated Annotation of Enzyme Superfamilies
The evolution of enzymes affects how well a species can adapt to new environmental conditions. During enzyme evolution, certain aspects of molecular function are conserved while other aspects can vary. Aspects of function that are more difficult to change or that need to be reused in multiple contexts are often conserved, while those that vary may indicate functions that are more easily changed or that are no longer required. In analogy to the study of conservation patterns in enzyme sequences and structures, we have examined the patterns of conservation and variation in enzyme function by analyzing graph isomorphisms among enzyme substrates of a large number of enzyme superfamilies. This systematic analysis of substrate substructures establishes the conservation patterns that typify individual superfamilies. Specifically, we determined the chemical substructures that are conserved among all known substrates of a superfamily and the substructures that are reacting in these substrates and then examined the relationship between the two. Across the 42 superfamilies that were analyzed, substantial variation was found in how much of the conserved substructure is reacting, suggesting that superfamilies may not be easily grouped into discrete and separable categories. Instead, our results suggest that many superfamilies may need to be treated individually for analyses of evolution, function prediction, and guiding enzyme engineering strategies. Annotating superfamilies with these conserved and reacting substructure patterns provides information that is orthogonal to information provided by studies of conservation in superfamily sequences and structures, thereby improving the precision with which we can predict the functions of enzymes of unknown function and direct studies in enzyme engineering. Because the method is automated, it is suitable for large-scale characterization and comparison of fundamental functional capabilities of both characterized and uncharacterized enzyme superfamilies
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