Symmetric signaling by an asymmetric 1 erythropoietin : 2 erythropoietin receptor complex

Thesis (M. Eng.)--Massachusetts Institute of Technology, Biological Engineering Division, 2008.Includes bibliographical references (p. 43-46).One erythropoietin molecule binds asymmetrically to two identical receptor monomers via erythropoietin site 1 and site 2, although it is unclear how asymmetry affects receptor activation and signaling. Here we report the computational design and experimental validation of two mutant erythropoietin receptors: one that binds only to erythropoietin site 1 but not site 2, and one that binds only to site 2 but not site 1. Expression of either mutant receptor alone in Ba/F3 cells cannot elicit a signal in response to erythropoietin, but when co-expressed, there is a proliferative response and activation of the JAK2 Stat5 signaling pathway. A truncated erythropoietin receptor with only one cytosolic tyrosine (Y343), on only one receptor monomer is sufficient for signaling in response to erythropoietin, regardless of the monomer on which it is located. The same results apply to having only one conserved juxtamembrane hydrophobic L253 or W258 residue, essential for JAK2 activation, in the full-length receptor dimer. We conclude that despite asymmetry in the ligand-receptor dimer interaction, both sides are competent for signaling, and we suggest that the receptors signal equally.by Yingxin Zhang.M.Eng

Immobilized biocatalytic process to prepare enantiopure pregabalin intermediate using engineered hydantoinase

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Identification of Core Technology of Digital SPC Exchange and Intelligentialize Prospect of Electronic Communication Equipment Industry

digital SPC switch belongs to the communication system equipment manufacturing class and belongs to the high-tech industry. Mastering the core technology of digital SPC switch is related to communication security and national information security. HuaWei has already mastered the core technology of digital SPC switch, and on this basis has accumulated the core technology capability to develop intelligently. In this paper, patent data is used to analyze the patent family of digital SPC switches at home and abroad, and based on this analysis and identification of core technologies, and finally, the intelligent development direction of the industry is predicted

Joint Detection Algorithm for Multiple Cognitive Users in Spectrum Sensing

Spectrum sensing technology is a crucial aspect of modern communication technology, serving as one of the essential techniques for efficiently utilizing scarce information resources in tight frequency bands. This paper first introduces three common logical circuit decision criteria in hard decisions and analyzes their decision rigor. Building upon hard decisions, the paper further introduces a method for multi-user spectrum sensing based on soft decisions. Then the paper simulates the false alarm probability and detection probability curves corresponding to the three criteria. The simulated results of multi-user collaborative sensing indicate that the simulation process significantly reduces false alarm probability and enhances detection probability. This approach effectively detects spectrum resources unoccupied during idle periods, leveraging the concept of time-division multiplexing and rationalizing the redistribution of information resources. The entire computation process relies on the calculation principles of power spectral density in communication theory, involving threshold decision detection for noise power and the sum of noise and signal power. It provides a secondary decision detection, reflecting the perceptual decision performance of logical detection methods with relative accuracy.Comment: https://aei.ewapublishing.org/article.html?pk=e24c40d220434209ae2fe2e984bcf2c

Net Ecosystem Production (NEP) of the Great Plains, United States

Gross primary production (GPP) and ecosystem respiration (Re) are the fundamental environmental characteristics that promote carbon exchanges with the atmosphere (Chapin and others, 2009), although other exchanges of carbon, such as direct oxidation (Lovett and others, 2006), can modify net ecosystem production (NEP). The accumulation of carbon in terrestrial ecosystems results in systems in which soil organic matter (SOM) carbon often exceeds biomass carbon (Post and Kwon, 2000). This SOM pool exists at a steady state between GPP and Re in ecosystems unless drivers change or the ecosystem endures environmental perturbations (for example, climatic). As indicated by Wilhelm and others (2011), conversion of grasslands to agriculture and cultivation can result in reduced soil carbon, with the release of carbon dioxide (CO2 ) to the atmosphere by stimulated oxidation and higher Re; therefore, land-use and land management practices have clear effects on NEP, with potential repercussions on ecosystems. The recent demand for biofuels has changed land-use and cropping patterns, especially in Midwestern United States (Wilhelm and others, 2011). It is important to ensure the sustainability of these and other land uses and to assess the effects on NE

Evaluation of Carbon Fluxes and Trends (2000e2008) in the Greater Platte River Basin: A Sustainability Study for Potential Biofuel Feedstock Development

This study evaluates the carbon fluxes and trends and examines the environmental sustainability (e.g., carbon budget, source or sink) of the potential biofuel feedstock sites identified in the Greater Platte River Basin (GPRB). A 9-year (2000e2008) time series of net ecosystem production (NEP), a measure of net carbon absorption or emission by ecosystems, was used to assess the historical trends and budgets of carbon flux for grasslands in the GPRB. The spatially averaged annual NEP (ANEP) for grassland areas that are possibly suitable for biofuel expansion (productive grasslands) was 71e169 g C m2 year1 during 2000e2008, indicating a carbon sink (more carbon is absorbed than released) in these areas. The spatially averaged ANEP for areas not suitable for biofuel feedstock development (less productive or degraded grasslands) was 47 to 69 g C m2 year1 during 2000e2008, showing a weak carbon source or a weak carbon sink (carbon emitted is nearly equal to carbon absorbed). The 9-year pre-harvest cumulative ANEP was 1166 g C m2 for the suitable areas (a strong carbon sink) and 200 g C m2 for the non-suitable areas (a weak carbon sink). Results demonstrate and confirm that our method of dynamic modeling of ecosystem performance can successfully identify areas desirable and sustainable for future biofuel feedstock development. This study provides useful information for land managers and decision makers to make optimal land use decisions regarding biofuel feedstock development and sustainability

Youth participation in cultural heritage management:a conceptual framework

The management of cultural heritage is no longer exclusive to heritage professionals. The engagement of various stakeholders, particularly underrepresented groups in communities, is crucial to promote inclusiveness in heritage management practices. As future decision-makers, youth are vital to be engaged, yet their participation remains at a low level due to the underestimation of youth capacities and a lack of motivation among youth. Little research has been done to comprehensively conceptualise youth participation and frame it in the context of cultural heritage management. To fill this gap, an integrative literature review was conducted using academic and grey literature from participatory urban planning, design, governance, and heritage management fields. The results show that existing theories have made valuable insights into approaching youth participation by identifying the definition and roles of youth, levels of participation, and methods of engagement. However, they have so far failed to fully address the fluid nature of youth engagement and lack reflections from youth perspectives towards their initiatives to participatory practices. Drawing on the results, we propose a new conceptual framework consisting of four dimensions: purpose, positioning, perspectives, and power relations, which define youth participation theoretically and methodologically in cultural heritage management