Genetic Evidence for High-Altitude Adaptation in Tibet Simonson, Tatum S; Yang, Yingzhong; Huff, Chad D ...
Science (American Association for the Advancement of Science),
07/2010, Volume:
329, Issue:
5987
Journal Article
Peer reviewed
Tibetans have lived at very high altitudes for thousands of years, and they have a distinctive suite of physiological traits that enable them to tolerate environmental hypoxia. These phenotypes are ...clearly the result of adaptation to this environment, but their genetic basis remains unknown. We report genome-wide scans that reveal positive selection in several regions that contain genes whose products are likely involved in high-altitude adaptation. Positively selected haplotypes of EGLN1 and PPARA were significantly associated with the decreased hemoglobin phenotype that is unique to this highland population. Identification of these genes provides support for previously hypothesized mechanisms of high-altitude adaptation and illuminates the complexity of hypoxia-response pathways in humans.
In this paper, composite silica gel and potassium formate as typical organic weak acid salts is proposed to use in desiccant coated heat exchanger (DCHE). An experimental study on dynamic adsorption ...performance of desiccant coated metal sheet samples is conducted to obtain results with different proportions of silica gel and potassium format. A DCHE testing platform is then used to compare thermodynamic performance between single silica gel coated heat exchanger (SCHE) and composite potassium formate and silica gel coated heat exchanger (PSCHE). It is found that impregnating potassium formate into porous silica gel is an effective method to improve adsorption capacity, and 75% saturated potassium formate solution is recommended to constitute composite desiccant under experimental conditions. Compared with SG coated sheet, on average the maximum adsorption mass of SG&0.75PF coated sheet increases 2–3 times. Besides, PSCHE can obtain about 20% higher moisture removal capacity compared with SCHE under experimental condition, meaning the utilization of composite silica gel and potassium formate desiccant can effectively improve dehumidification capacity. PSCHE also can obtain 50% higher total cooling capacity compared with SCHE.
•Composite silica gel and potassium formate desiccant is proposed.•Experiments are conducted to obtain dynamic performance.•75% saturated potassium formate solution is recommended.•Composite desiccant and its coating heat exchanger have improved performance.
Rotary desiccant wheel cooling system operates on the principle of adsorption dehumidification and evaporative cooling. The system adopts natural substance as working fluid and can be driven by low ...grade thermal energy such as solar energy. Due to these merits, solar powered rotary desiccant wheel cooling system has recognized as one of good alternatives to conventional vapor compression air conditioning system and has obtained increasing interests in the past years. This paper aims to summarize recent research developments related to solar powered rotary desiccant wheel cooling system and to provide information for potential application. Based on whether auxiliary refrigeration system is adopted, the systems are divided in to two categories: separate solar powered rotary desiccant wheel cooling systems and hybrid solar powered rotary desiccant wheel cooling systems. Within the first category, separate solar powered rotary desiccant wheel cooling systems are reviewed according to different types of solar collector. It can be found that these researches mainly focus on feasibility study of such system under different climates. Results show that separate solar powered rotary desiccant wheel cooling systems can be adopted in several representative cities in Europe, Asia, Australia and Africa. However, system performance in terms of solar fraction and thermal coefficient of performance varies greatly with respect to different operation conditions. For the second category, works related to hybrid solar powered rotary desiccant wheel cooling systems are grouped by types of auxiliary refrigeration systems. It can be found that vapor compression system is widely adopted in these hybrid systems. Also, due to both solar energy and electricity are consumed in hybrid systems, primary energy consumption is an important performance index. Results show that hybrid solar powered rotary desiccant wheel cooling system can obtain significant energy saving compared with conventional vapor compression system.
In order to simplify the manufacturing process of variable reluctance (VR) resolvers for hybrid electric vehicle/electric vehicle (HEV/EV) applications, a novel VR resolver with nonoverlapping ...tooth-coil windings is proposed in this paper. A comparison of the winding configurations is first carried out between the existing and the proposed designs, followed by the description of the operating principle. Furthermore, the influence of actual application conditions is investigated by finite-element (FE) analyses, including operating speed and assembling eccentricity. In addition, identical stator and windings of the novel design can be employed in three resolvers of different rotor saliencies. The voltage difference among the three rotor combinations, as well as the detecting accuracy, is further investigated. Finally, prototypes are fabricated and tested to verify the analyses.
Composite solid desiccant materials are fabricated by impregnating hygroscopic salts into pores of different silica gels. In this paper, sorption characteristics of composite desiccants with ...different pore sizes (namely, 2–3nm, 7–8nm and 9–10nm) of silica gels and different salts in terms of LiCl, LiBr and CaCl2 are tested and analyzed. Researches on nitrogen adsorption suggest that, due to impregnated salt particles, composite desiccants are different from those of pure silica gels and have smaller surface area and pore volume. Sorption isotherms and sorption kinetics with respect to different composite desiccant materials are tested and fitted with the Dubinin–Astakhov (D–A) equation and the Linear Driving Force (LDF) model, respectively. Results showed that both the pore size of silica gel substrates and categories of impregnated salts affect the sorption characteristics of composite desiccants. Microporous silica gel with pore size of 2–3nm is not fit for preparing composite desiccants due to decreased water sorption quantity and sorption rate. Type B and mesoporous silica gels can be a promising host matrix of composite desiccant owing to enhanced water sorption quantity and favorable sorption rate. In addition, composite desiccants employing LiCl have the best sorption properties, while CaCl2 and LiBr follow next.
•Composite silica gels were prepared for solid desiccant cooling systems.•Morphologies of composite desiccants were different from those of pure silica gels.•Salt category and pore size affected the sorption performance of composite desiccants.•Performance curves of composite materials were divided into three sections.
The genetic architecture of the human cerebral cortex Ching, Christopher R K; Zsembik, Leo C P; Alhusaini, Saud ...
Science (American Association for the Advancement of Science),
03/2020, Volume:
367, Issue:
6484
Journal Article
Peer reviewed
Open access
The cerebral cortex underlies our complex cognitive capabilities, yet little is known about the specific genetic loci that influence human cortical structure. To identify genetic variants that affect ...cortical structure, we conducted a genome-wide association meta-analysis of brain magnetic resonance imaging data from 51,665 individuals. We analyzed the surface area and average thickness of the whole cortex and 34 regions with known functional specializations. We identified 199 significant loci and found significant enrichment for loci influencing total surface area within regulatory elements that are active during prenatal cortical development, supporting the radial unit hypothesis. Loci that affect regional surface area cluster near genes in Wnt signaling pathways, which influence progenitor expansion and areal identity. Variation in cortical structure is genetically correlated with cognitive function, Parkinson's disease, insomnia, depression, neuroticism, and attention deficit hyperactivity disorder.
Synchrotron X-ray radiography was used to visualize the liquid water accumulation in polymer electrolyte membrane (PEM) fuel cells to compare the impact of carbon substrate thickness on water ...management. A differential fuel cell with an active area of 0.68cm2 and rib/channel width of 0.2mm was custom-made to provide 1-dimensional (1D) conditions over the active area. The fuel cell with the thin substrate (TGP-H-030) outperformed the fuel cell with the thick substrate (TGP-H-060). The fuel cell with the thinner substrate exhibited a higher limiting current density, less liquid water in the microporous layer (MPL)-substrate transition region, and reduced oxygen transport resistance measured through electrochemical impedance spectroscopy (EIS). The compression behaviour of each GDL was also investigated through two consecutive fuel cell assemblies. The pressure in the second assembly was lower than that for the initial assemblies for both GDLs, and this significant change in assembly pressure was more pronounced for the thinner GDL (TGP-H-030). The resulting interfacial contact between the catalyst layer and the GDL was degraded, which manifested in the microscale displacement of fuel cell materials during operation (detected as a negative liquid water thickness). While the thinner GDL provided superior performance, the long term effects of material deformation may exacerbate a heterogeneous distribution of liquid water that could also impact the performance.
Abstract NMDA receptors are found in neurons both at synapses and in extrasynaptic locations. Extrasynaptic locations are poorly characterized. Here we used preembedding immunoperoxidase and ...postembedding immunogold electron microscopy and fluorescence light microscopy to characterize extrasynaptic NMDA receptor locations in dissociated hippocampal neurons in vitro and in the adult and postnatal hippocampus in vivo . We found that extrasynaptic NMDA receptors on neurons in vivo and in vitro were usually concentrated at points of contact with adjacent processes, which were mainly axons, axon terminals, or glia. Many of these contacts were shown to contain adhesion factors such as cadherin and catenin. We also found associations of extrasynaptic NMDA receptors with the membrane associated guanylate kinase (MAGUKs), postsynaptic density (PSD)-95 and SAP102. Developmental differences were also observed. At postnatal day 2 in vivo , extrasynaptic NMDA receptors could often be found at sites with distinct densities whereas dense material was seen only rarely at sites of extrasynaptic NMDA receptors in the adult hippocampus in vivo . This difference probably indicates that many sites of extrasynaptic NMDA receptors in early postnatal ages represent synapse formation or possibly sites for synapse elimination. At all ages, as suggested in both in vivo and in vitro studies, extrasynaptic NMDA receptors on dendrites or the sides of spines may form complexes with other proteins, in many cases, at stable associations with adjacent cell processes. These associations may facilitate unique functions for extrasynaptic NMDA receptors.
Abstract
JASPAR (http://jaspar.genereg.net) is an open-access database of curated, non-redundant transcription factor (TF)-binding profiles stored as position frequency matrices (PFMs) and TF ...flexible models (TFFMs) for TFs across multiple species in six taxonomic groups. In the 2018 release of JASPAR, the CORE collection has been expanded with 322 new PFMs (60 for vertebrates and 262 for plants) and 33 PFMs were updated (24 for vertebrates, 8 for plants and 1 for insects). These new profiles represent a 30% expansion compared to the 2016 release. In addition, we have introduced 316 TFFMs (95 for vertebrates, 218 for plants and 3 for insects). This release incorporates clusters of similar PFMs in each taxon and each TF class per taxon. The JASPAR 2018 CORE vertebrate collection of PFMs was used to predict TF-binding sites in the human genome. The predictions are made available to the scientific community through a UCSC Genome Browser track data hub. Finally, this update comes with a new web framework with an interactive and responsive user-interface, along with new features. All the underlying data can be retrieved programmatically using a RESTful API and through the JASPAR 2018 R/Bioconductor package.
Interleukin-23 (IL-23) and CD4
+ T helper 17 (Th17) cells are thought to be critical in psoriasis pathogenesis. Here, we report that IL-23 predominantly stimulated dermal γδ T cells to produce IL-17 ...that led to disease progression. Dermal γδ T cells constitutively expressed the IL-23 receptor (IL-23R) and transcriptional factor RORγt. IL-17 production from dermal γδ T cells was independent of αβ T cells. The epidermal hyperplasia and inflammation induced by IL-23 were significantly decreased in T cell receptor δ-deficient (
Tcrd
−/−) and IL-17 receptor-deficient (
Il17ra
−/−) mice but occurred normally in
Tcra
−/− mice. Imiquimod-induced skin pathology was also significantly decreased in
Tcrd
−/− mice. Perhaps further promoting disease progression, IL-23 stimulated dermal γδ T cell expansion. In psoriasis patients, γδ T cells were greatly increased in affected skin and produced large amounts of IL-17. Thus, IL-23-responsive dermal γδ T cells are the major IL-17 producers in the skin and may represent a novel target for the treatment of psoriasis.
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► Dermal γδ T cells are the major source of IL-17 in the skin upon IL-23 stimulation ► Dermal γδ T cells have features with other IL-17-producing cells but also are unique ► γδ T cells are required for dermal inflammation and hyperplasia ► Dermal γδ T cells from human psoriatic skin are increased and produce IL-17
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