460 research outputs found
Many Children Left Behind? Textbooks and Test Scores in Kenya
A randomized evaluation suggests that a program which provided official textbooks to randomly selected rural Kenyan primary schools did not increase test scores for the average student. In contrast, the previous literature suggests that textbook provision has a large impact on test scores. Disaggregating the results by students? initial academic achievement suggests a potential explanation for the lack of an overall impact. Textbooks increased scores for students with high initial academic achievement and increased the probability that the students who had made it to the selective final year of primary school would go on to secondary school. However, students with weaker academic backgrounds did not benefit from the textbooks. Many pupils could not read the textbooks, which are written in English, most students? third language. The results are consistent with the hypothesis that the Kenyan education system and curricular materials are oriented to the academically strongest students rather than to typical students. More generally, many students may be left behind in societies that combine 1) a centralized, unified education system; 2) the heterogeneity in student preparation associated with rapid expansion of education; and 3) disproportionate elite power.
A mathematical model of the tetrapyrrole biosynthesis pathway
The tetrapyrrole biosynthesis pathway is a key part in chlorophyll production and is essential for plant survival. It involves numerous interacting compounds and, crucially, light. The understanding of the complex regulation processes involved has been the focus of extensive experimental research providing a large source of data. A particular set of data, concerned with the modelling described in this report, involves 24 hour timecourse data from seedlings exposed to constant light, following a three day period of growth from seed in darkness. This data includes the levels of key components such as chlorophyll, ATP, chlorophyllide and proto-chlorophyllide. Amongst the questions posed in the study-group were: i) Can the timecourse data be predicted by a model? ii) Can it predict the dierences in levels of various components in found mutant strains.
To address these questions, we present in this report a model consisting of a coupled system of nonlinear ODEs that describes a simplied version of the tetrapyrrole pathway based on mass action laws. Model simulations produced results that agree qualitatively well with most, but not all, of the available timecourse data obtained from wild-type and mutant strains. Nearly all of the model's parameters are not known, so the values used in these simulations are based on estimates of the relative timescales of the reactions. An attempt at improving these estimates using data tting techniques is also discussed
SBMLtoODEjax: Efficient Simulation and Optimization of Biological Network Models in JAX
Advances in bioengineering and biomedicine demand a deep understanding of the
dynamic behavior of biological systems, ranging from protein pathways to
complex cellular processes. Biological networks like gene regulatory networks
and protein pathways are key drivers of embryogenesis and physiological
processes. Comprehending their diverse behaviors is essential for tackling
diseases, including cancer, as well as for engineering novel biological
constructs. Despite the availability of extensive mathematical models
represented in Systems Biology Markup Language (SBML), researchers face
significant challenges in exploring the full spectrum of behaviors and
optimizing interventions to efficiently shape those behaviors. Existing tools
designed for simulation of biological network models are not tailored to
facilitate interventions on network dynamics nor to facilitate automated
discovery. Leveraging recent developments in machine learning (ML), this paper
introduces SBMLtoODEjax, a lightweight library designed to seamlessly integrate
SBML models with ML-supported pipelines, powered by JAX. SBMLtoODEjax
facilitates the reuse and customization of SBML-based models, harnessing JAX's
capabilities for efficient parallel simulations and optimization, with the aim
to accelerate research in biological network analysis
Vibrational dynamics changes of protein hydration water across the dynamic transition
The vibrational dynamics of protein hydration water has been studied by incoherent neutron scattering. Experiments on a sample of fully deuterated maltose binding protein allowed us to single out the hydration water susceptibility. The main inelastic features, corresponding to hydrogen-bond bending, hydrogen-bond stretching and librational excitations, have been followed over a temperature range extending from 50 to 300 K. It turns out that the temperature dependence of the hydrogen-bond stretching contribution is quite similar to that of the mean square displacements deduced by the quasielastic signal, thus suggesting a close relationship between the anharmonicity of longitudinal phonon-like motions and the onset of diffusive molecular dynamics. On the other hand, both hydrogen-bond bending and librational excitations show a temperature dependence consistent with a harmonic character over the whole temperature range
E-government and local good governance : a pilot project in Fez, Morocco
This paper presents a research project working towards building a sustainable pilot E-Government system for the ancient city of Fez in the developing country of Morocco. Specifically, this article goes through the range of understandings related to concepts of governance, good governance, and e-government to identify ways to put in practice these notions and facilitate systematic assessment of outcomes and results of the project implementation. The article presents a methodology (Outcome Analysis) and identifies indicators for enabling a project Outcome Analysis as a measurement of the project's contribution to the improvement of good governance. Such a systematic assessment aims to contribute to the generation of knowledge and dissemination of lessons learned concerning the implications of e-Government implementation for good governance
In Vivo Water Dynamics in Shewanella oneidensis Bacteria at High Pressure
Abstract: Following observations of survival of microbes and other life forms in deep subsurface environments it is necessary to understand their biological functioning under high pressure conditions. Key aspects of biochemical reactions and transport processes within cells are determined by the intracellular water dynamics. We studied water diffusion and rotational relaxation in live Shewanella oneidensis bacteria at pressures up to 500 MPa using quasi-elastic neutron scattering (QENS). The intracellular diffusion exhibits a significantly greater slowdown (by −10–30%) and an increase in rotational relaxation times (+10–40%) compared with water dynamics in the aqueous solutions used to resuspend the bacterial samples. Those results indicate both a pressure-induced viscosity increase and slowdown in ionic/macromolecular transport properties within the cells affecting the rates of metabolic and other biological processes. Our new data support emerging models for intracellular organisation with nanoscale water channels threading between macromolecular regions within a dynamically organized structure rather than a homogenous gel-like cytoplasm
Cerebral Arterial Stenoses and Stroke: Novel Features of Aicardi-Goutières Syndrome Caused by the Arg164X Mutation in SAMHD1 Are Associated with Altered Cytokine Expression
Aicardi-Goutières syndrome (AGS) is a rare inborn multisystemic disease, resembling intrauterine viral infection and resulting in psychomotor retardation, spasticity and chilblain-like skin lesions. Diagnostic criteria include intracerebral calcifications and elevated interferon-alpha and pterin levels in cerebrospinal fluid (CSF). We report on four adult siblings with unknown neurodegenerative disease presenting with cerebrovascular stenoses, stroke and glaucoma in childhood, two of whom died at the age of 40 and 29 years. Genome-wide homozygosity mapping identified 170 candidate genes embedded in a common haplotype of 8Mb on chromosome 20q11-13. Next generation sequencing of the entire region identified the c.490C>T (p.Arg164X) mutation in SAMHD1, a gene most recently described in AGS, on both alleles in all affected siblings. Clinical diagnosis of AGS was then confirmed by demonstrating intracerebral calcifications on cranial computed tomography in all siblings and elevated pterin levels in CSF in three of them. In patient fibroblasts, lack of SAMHD1 protein expression was associated with increased basal expression of IL8, while stimulated expression of IFNB1 was reduced. We conclude that cerebrovascular stenoses and stroke associated with the Arg164X mutation in SAMHD1 extend the phenotypic spectrum of AGS. The observed vascular changes most likely reflect a vasculitis caused by dysregulated inflammatory stress response. © 2010 Wiley-Liss, Inc
Consensus recommendations on the treatment of opioid use disorder in the emergency department
The treatment of opioid use disorder with buprenorphine and methadone reduces morbidity and mortality in patients with opioid use disorder. The initiation of buprenorphine in the emergency department (ED) has been associated with increased rates of outpatient treatment linkage and decreased drug use when compared to patients randomized to receive standard ED referral. As such, the ED has been increasingly recognized as a venue for the identification and initiation of treatment for opioid use disorder, but no formal American College of Emergency Physicians (ACEP) recommendations on the topic have previously been published. The ACEP convened a group of emergency physicians with expertise in clinical research, addiction, toxicology, and administration to review literature and develop consensus recommendations on the treatment of opioid use disorder in the ED. Based on literature review, clinical experience, and expert consensus, the group recommends that emergency physicians offer to initiate opioid use disorder treatment with buprenorphine in appropriate patients and provide direct linkage to ongoing treatment for patients with untreated opioid use disorder. These consensus recommendations include strategies for opioid use disorder treatment initiation and ED program implementation. They were approved by the ACEP board of directors in January 2021
Monopoly Sale of a Network Good
This paper studies the problem of a monopolist who sells a network good through a price posting scheme. The scheme posts a price of every possible allocation for each buyer, who are then asked to report their private information to the seller. The seller then implements the allocation based on the reports. The social choice functions that are ex post implementable through such a sales scheme are characterized, and the conditions are identified under which the revenue maximizing scheme has the property that the price of a larger network is more affordable than that of a smaller network
- …