277 research outputs found
Ensemble evaluation of hydrological model hypotheses
It is demonstrated for the first time how model parameter, structural and data uncertainties can be accounted for explicitly and simultaneously within the Generalized Likelihood Uncertainty Estimation (GLUE) methodology. As an example application, 72 variants of a single soil moisture accounting store are tested as simplified hypotheses of runoff generation at six experimental grassland field-scale lysimeters through model rejection and a novel diagnostic scheme. The fields, designed as replicates, exhibit different hydrological behaviors which yield different model performances. For fields with low initial discharge levels at the beginning of events, the conceptual stores considered reach their limit of applicability. Conversely, one of the fields yielding more discharge than the others, but having larger data gaps, allows for greater flexibility in the choice of model structures. As a model learning exercise, the study points to a “leaking” of the fields not evident from previous field experiments. It is discussed how understanding observational uncertainties and incorporating these into model diagnostics can help appreciate the scale of model structural error
Octet baryon electromagnetic form factors in nuclear medium
We study the octet baryon electromagnetic form factors in nuclear matter
using the covariant spectator quark model extended to the nuclear matter
regime. The parameters of the model in vacuum are fixed by the study of the
octet baryon electromagnetic form factors. In nuclear matter the changes in
hadron properties are calculated by including the relevant hadron masses and
the modification of the pion-baryon coupling constants calculated in the
quark-meson coupling model. In nuclear matter the magnetic form factors of the
octet baryons are enhanced in the low region, while the electric form
factors show a more rapid variation with . The results are compared with
the modification of the bound proton electromagnetic form factors observed at
Jefferson Lab. In addition, the corresponding changes for the bound neutron are
predicted.Comment: Version accepted for publication in J.Phys. G. Few changes. 40 pages,
14 figures and 8 table
Generational differences in local identities, participation in social movements, and migration intention among Hong Kong people
We adopt and extend Hirschman’s (1970) Exit, Voice, and Loyalty framework to investigate the associations between local identities, participation in social movements, and migration intention in Hong Kong. Data are from random sampled surveys collected from February to April 2021, June to August 2021, and March to June 2022 (N = 3,003) from people in Hong Kong with the British National (Overseas) status. The findings show that the Hong Konger identity is associated with a higher level of participation in social movements and a stronger migration intention. There are few variations in these associations across the generations. Furthermore, participation in social movements is a strong push factor to migration, and no generational difference in the association is found.
Overall, the findings imply that when political freedom is in decline, as in the case of Hong Kong, a local identity is associated with voicing for reforms. In the case of failed social movements, a local identity and previous experiences in voicing out are associated with a higher chance of exit to another country
Challenges in using land use and land cover data for global change studies
Land use and land cover data play a central role in climate change assessments. These data originate from different sources and inventory techniques. Each source of land use/cover data has its own domain of applicability and quality standards. Often data are selected without explicitly considering the suitability of the data for the specific application, the bias originating from data inventory and aggregation, and the effects of the uncertainty in the data on the results of the assessment. Uncertainties due to data selection and handling can be in the same order of magnitude as uncertainties related to the representation of the processes under investigation. While acknowledging the differences in data sources and the causes of inconsistencies, several methods have been developed to optimally extract information from the data and document the uncertainties. These methods include data integration, improved validation techniques and harmonization of classification systems. Based on the data needs of global change studies and the data availability, recommendations are formulated aimed at optimal use of current data and focused efforts for additional data collection. These include: improved documentation using classification systems for land use/cover data; careful selection of data given the specific application and the use of appropriate scaling and aggregation methods. In addition, the data availability may be improved by the combination of different data sources to optimize information content while collection of additional data must focus on validation of available data sets and improved coverage of regions and land cover types with a high level of uncertainty. Specific attention in data collection should be given to the representation of land management (systems) and mosaic landscape
Stress-Induced Reinstatement of Drug Seeking: 20 Years of Progress
In human addicts, drug relapse and craving are often provoked by stress. Since 1995, this clinical scenario has been studied using a rat model of stress-induced reinstatement of drug seeking. Here, we first discuss the generality of stress-induced reinstatement to different drugs of abuse, different stressors, and different behavioral procedures. We also discuss neuropharmacological mechanisms, and brain areas and circuits controlling stress-induced reinstatement of drug seeking. We conclude by discussing results from translational human laboratory studies and clinical trials that were inspired by results from rat studies on stress-induced reinstatement. Our main conclusions are (1) The phenomenon of stress-induced reinstatement, first shown with an intermittent footshock stressor in rats trained to self-administer heroin, generalizes to other abused drugs, including cocaine, methamphetamine, nicotine, and alcohol, and is also observed in the conditioned place preference model in rats and mice. This phenomenon, however, is stressor specific and not all stressors induce reinstatement of drug seeking. (2) Neuropharmacological studies indicate the involvement of corticotropin-releasing factor (CRF), noradrenaline, dopamine, glutamate, kappa/dynorphin, and several other peptide and neurotransmitter systems in stress-induced reinstatement. Neuropharmacology and circuitry studies indicate the involvement of CRF and noradrenaline transmission in bed nucleus of stria terminalis and central amygdala, and dopamine, CRF, kappa/dynorphin, and glutamate transmission in other components of the mesocorticolimbic dopamine system (ventral tegmental area, medial prefrontal cortex, orbitofrontal cortex, and nucleus accumbens). (3) Translational human laboratory studies and a recent clinical trial study show the efficacy of alpha-2 adrenoceptor agonists in decreasing stress-induced drug craving and stress-induced initial heroin lapse
An Allosteric Modulator of 7 Nicotinic Receptors, N-(5-Chloro-2,4-dimethoxyphenyl)-N'-(5-methyl-3-isoxazolyl)-urea (PNU-120596), Causes Conformational Changes in the Extracellular Ligand Binding Domain Similar to Those Caused by Acetylcholine
Nicotinic acetylcholine receptors are implicated in several neuropsychiatric disorders, including nicotine addiction, Alzheimer's, schizophrenia, and depression. Therefore, they represent a critical molecular target for drug development and targeted therapeutic intervention. Understanding the molecular mechanisms by which allosteric modulators enhance activation of these receptors is crucial to the development of new drugs. We used the substituted cysteine accessibility method to study conformational changes induced by the positive allosteric modulator N-(5-chloro-2,4-dimethoxyphenyl)-N′-(5-methyl-3-isoxazolyl)-urea (PNU-120596) in the extracellular ligand binding domain of α7 nicotinic receptors carrying the L247T mutation. PNU-120596 caused changes in cysteine accessibility at the inner beta sheet, transition zone, and agonist binding site. These changes in accessibility are similar to but not identical to those caused by ACh alone. In particular, PNU-120596 induced changes in MTSEA accessibility at N170C (in the transition zone) that were substantially different from those evoked by acetylcholine (ACh). We found that PNU-120596 induced changes at position E172C in the absence of allosteric modulation. We identified a cysteine mutation of the agonist binding site (W148C) that exhibited an unexpected phenotype in which PNU-120596 acts as a full agonist. In this mutant, ACh-evoked currents were more sensitive to thiol modification than PNU-evoked currents, suggesting that PNU-120596 does not bind at unoccupied agonist-binding sites. Our results provide evidence that binding sites for PNU-120596 are not in the agonist-binding sites and demonstrate that positive allosteric modulators such as PNU-120596 enhance agonist-evoked gating of nicotinic receptors by eliciting conformational effects that are similar but nonidentical to the gating conformations promoted by ACh
Is the Bankruptcy Code an Adequate Mechanism for Resolving the Distress of Systemically Important Institutions?
The President and members of Congress are considering proposals that would give the government broad authority to rescue financial institutions whose failure might threaten market stability. These systemically important institutions include bank and insurance holding companies, investment banks, and other large, highly leveraged, and interconnected entities that are not currently subject to federal resolution authority. Interest in these proposals stems from the credit crisis, particularly the bankruptcy of Lehman Brothers. That bankruptcy, according to some observers, caused massive destabilization in credit markets for two reasons. First, market participants were surprised that the government would permit a massive market player to undergo a costly Chapter 11 proceeding. A very different policy had been applied to other systemically important institutions such as Bear Steams, Fannie Mae, and Freddie Mac. Second, the bankruptcy filing triggered fire sales of Lehman assets. Fire sales were harmful to other non-distressed institutions that held similar assets, which suddenly plummeted in value. They were also harmful to any institution holding Lehman\u27s commercial paper, which functioned as a store of value for entities such as the Primary Reserve Fund. Fire sales destroyed Lehman\u27s ability to honor these claims.
Lehman\u27s experience and the various bailouts (of AIG, Bear Steams, and other distressed institutions) have produced two kinds of policy proposals. One calls for wholesale reform, including creation of a systemic risk regulator with authority to seize and stabilize systemically important institutions. Another is more modest and calls for targeted amendments to the Bankruptcy Code and greater government monitoring of market risks. This approach would retain bankruptcy as the principal mechanism for resolving distress at non-bank institutions, systemically important or not.
Put differently, current debates hinge on one question: is the Bankruptcy Code an adequate mechanism for resolving the distress of systemically important institutions? One view says no, and advances wholesale reform. Another view says yes, with some adjustments. This Essay evaluates these competing views: Section II discusses the current structure of the Bankruptcy Code and its limited ability to protect markets from failing systemically important institutions. Section III outlines policy responses. In Section IV, I conclude that the Code is indeed inadequate for dealing with failures of systemically important institutions. A systemic risk regulator is needed because a judicially administered process cannot move with sufficient speed and expertise in response to rapidly changing economic conditions
100% RAG: Architectural Education | Theory vs. Practice, Volume 2, Number 4
100% RAG: Architectural Education | Theory vs. Practice, Syracuse School of Architecture, Student Newspaper, Volume 2, Number 4.
Student newsletter from student contributors of Syracuse School of Architecture in 1977
Reading from nowhere: assessed literary response, Practical Criticism and situated cultural literacy
School examinations of student responses to literature often present poetry blind or “unseen”, inviting decontextualised close reading consistent with the orientation-to-text associated with Practical Criticism (originating in the UK) and New Criticism (originating in the USA). The approach survives in the UK after curricular reforms and government have promulgated cultural literacy as foundational for learning. How is cultural literacy manifest in student responses to literature? To what extent can it be reconciled with Practical Criticism where the place of background knowledge in literary reading is negligible? This article explores their uneasy relationship in pedagogy, curricula and assessment for literary study, discussing classroom interactions in England and Northern Ireland where senior students (aged 16–17) of English Literature consider Yeats’ “culture-making” poem “Easter, 1916”. Using methods where teachers withhold contextual information as they elicit students’ responses, the divergent responses of each class appear to arise from differing access to background knowledge according to local though superficially congruent British cultures. The author proposes “situated cultural literacy” to advance the limited application of Practical Criticism in unseen tasks, acknowledge Richards’ original intent, and support the coherence of assessment with curricular arrangements invoking cultural literacy as a unifying principle
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