| 21. |
- Guseva, S., et al.
(författare)
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Bulk Transfer Coefficients Estimated From Eddy-Covariance Measurements Over Lakes and Reservoirs
- 2023
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Ingår i: Journal of Geophysical Research - Atmospheres. - : American Geophysical Union (AGU). - 2169-897X .- 2169-8996. ; 128:2
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Tidskriftsartikel (refereegranskat)abstract
- The drag coefficient, Stanton number and Dalton number are of particular importance for estimating the surface turbulent fluxes of momentum, heat and water vapor using bulk parameterization. Although these bulk transfer coefficients have been extensively studied over the past several decades in marine and large-lake environments, there are no studies analyzing their variability for smaller lakes. Here, we evaluated these coefficients through directly measured surface fluxes using the eddy-covariance technique over more than 30 lakes and reservoirs of different sizes and depths. Our analysis showed that the transfer coefficients (adjusted to neutral atmospheric stability) were generally within the range reported in previous studies for large lakes and oceans. All transfer coefficients exhibit a substantial increase at low wind speeds (<3 m s(-1)), which was found to be associated with the presence of gusts and capillary waves (except Dalton number). Stanton number was found to be on average a factor of 1.3 higher than Dalton number, likely affecting the Bowen ratio method. At high wind speeds, the transfer coefficients remained relatively constant at values of 1.6.10(-3), 1.4.10(-3), 1.0.10(-3), respectively. We found that the variability of the transfer coefficients among the lakes could be associated with lake surface area. In flux parameterizations at lake surfaces, it is recommended to consider variations in the drag coefficient and Stanton number due to wind gustiness and capillary wave roughness while Dalton number could be considered as constant at all wind speeds. Plain Language Summary In our study, we investigate the bulk transfer coefficients, which are of particular importance for estimation the turbulent fluxes of momentum, heat and water vapor in the atmospheric surface layer, above lakes and reservoirs. The incorrect representation of the surface fluxes above inland waters can potentially lead to errors in weather and climate prediction models. For the first time we made this synthesis using a compiled data set consisting of existing eddy-covariance flux measurements over 23 lakes and 8 reservoirs. Our results revealed substantial increase of the transfer coefficients at low wind speeds, which is often not taken into account in models. The observed increase in the drag coefficient (momentum transfer coefficient) and Stanton number (heat transfer coefficient) could be associated with the presence of wind gusts and capillary waves. In flux parameterizations at lake surface, it is recommended to consider them for accurate flux representation. Although the bulk transfer coefficients were relatively constant at high wind speeds, we found that the Stanton number systematically exceeds the Dalton number (water vapor transfer coefficient), despite the fact they are typically considered to be equal. This difference may affect the Bowen ratio method and result in biased estimates of lake evaporation.
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| 22. |
- Neville, S. L., et al.
(författare)
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The structural basis of bacterial manganese import
- 2021
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Ingår i: Science Advances. - : American Association for the Advancement of Science (AAAS). - 2375-2548. ; 7:32
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Tidskriftsartikel (refereegranskat)abstract
- Metal ions are essential for all forms of life. In prokaryotes, ATP-binding cassette (ABC) permeases serve as the primary import pathway for many micronutrients including the first-row transition metal manganese. However, the structural features of ionic metal transporting ABC permeases have remained undefined. Here, we present the crystal structure of the manganese transporter PsaBC from Streptococcus pneumoniae in an open-inward conformation. The type II transporter has a tightly closed transmembrane channel due to "extracellular gating" residues that prevent water permeation or ion reflux. Below these residues, the channel contains a hitherto unreported metal coordination site, which is essential for manganese translocation. Mutagenesis of the extracellular gate perturbs manganese uptake, while coordination site mutagenesis abolishes import. These structural features are highly conserved in metal-specific ABC transporters and are represented throughout the kingdoms of life. Collectively, our results define the structure of PsaBC and reveal the features required for divalent cation transport.
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| 23. |
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| 24. |
- Sasaguri, H, et al.
(författare)
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Recent Advances in the Modeling of Alzheimer's Disease
- 2022
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Ingår i: Frontiers in neuroscience. - : Frontiers Media SA. - 1662-4548 .- 1662-453X. ; 16, s. 807473-
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Tidskriftsartikel (refereegranskat)abstract
- Since 1995, more than 100 transgenic (Tg) mouse models of Alzheimer’s disease (AD) have been generated in which mutant amyloid precursor protein (APP) or APP/presenilin 1 (PS1) cDNA is overexpressed (1st generation models). Although many of these models successfully recapitulate major pathological hallmarks of the disease such as amyloid β peptide (Aβ) deposition and neuroinflammation, they have suffered from artificial phenotypes in the form of overproduced or mislocalized APP/PS1 and their functional fragments, as well as calpastatin deficiency-induced early lethality, calpain activation, neuronal cell death without tau pathology, endoplasmic reticulum stresses, and inflammasome involvement. Such artifacts bring two important uncertainties into play, these being (1) why the artifacts arise, and (2) how they affect the interpretation of experimental results. In addition, destruction of endogenous gene loci in some Tg lines by transgenes has been reported. To overcome these concerns, single App knock-in mouse models harboring the Swedish and Beyreuther/Iberian mutations with or without the Arctic mutation (AppNL–G–F and AppNL–F mice) were developed (2nd generation models). While these models are interesting given that they exhibit Aβ pathology, neuroinflammation, and cognitive impairment in an age-dependent manner, the model with the Artic mutation, which exhibits an extensive pathology as early as 6 months of age, is not suitable for investigating Aβ metabolism and clearance because the Aβ in this model is resistant to proteolytic degradation and is therefore prone to aggregation. Moreover, it cannot be used for preclinical immunotherapy studies owing to the discrete affinity it shows for anti-Aβ antibodies. The weakness of the latter model (without the Arctic mutation) is that the pathology may require up to 18 months before it becomes sufficiently apparent for experimental investigation. Nevertheless, this model was successfully applied to modulating Aβ pathology by genome editing, to revealing the differential roles of neprilysin and insulin-degrading enzyme in Aβ metabolism, and to identifying somatostatin receptor subtypes involved in Aβ degradation by neprilysin. In addition to discussing these issues, we also provide here a technical guide for the application of App knock-in mice to AD research. Subsequently, a new double knock-in line carrying the AppNL–F and Psen1P117L/WT mutations was generated, the pathogenic effect of which was found to be synergistic. A characteristic of this 3rd generation model is that it exhibits more cored plaque pathology and neuroinflammation than the AppNL–G–F line, and thus is more suitable for preclinical studies of disease-modifying medications targeting Aβ. Furthermore, a derivative AppG–F line devoid of Swedish mutations which can be utilized for preclinical studies of β-secretase modifier(s) was recently created. In addition, we introduce a new model of cerebral amyloid angiopathy that may be useful for analyzing amyloid-related imaging abnormalities that can be caused by anti-Aβ immunotherapy. Use of the App knock-in mice also led to identification of the α-endosulfine-KATP channel pathway as components of the somatostatin-evoked physiological mechanisms that reduce Aβ deposition via the activation of neprilysin. Such advances have provided new insights for the prevention and treatment of preclinical AD. Because tau pathology plays an essential role in AD pathogenesis, knock-in mice with human tau wherein the entire murine Mapt gene has been humanized were generated. Using these mice, the carboxy-terminal PDZ ligand of neuronal nitric oxide synthase (CAPON) was discovered as a mediator linking tau pathology to neurodegeneration and showed that tau humanization promoted pathological tau propagation. Finally, we describe and discuss the current status of mutant human tau knock-in mice and a non-human primate model of AD that we have successfully created.
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| 25. |
- Silver Karcioglu, Amanda L., et al.
(författare)
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Emerging Imaging Technologies for Parathyroid Gland Identification and Vascular Assessment in Thyroid Surgery : A Review from the American Head and Neck Society Endocrine Surgery Section
- 2023
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Ingår i: JAMA Otolaryngology - Head and Neck Surgery. - : American Medical Association (AMA). - 2168-6181. ; 149:3, s. 253-260
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Forskningsöversikt (refereegranskat)abstract
- Importance: Identification and preservation of parathyroid glands (PGs) remain challenging despite advances in surgical techniques. Considerable morbidity and even mortality result from hypoparathyroidism caused by devascularization or inadvertent removal of PGs. Emerging imaging technologies hold promise to improve identification and preservation of PGs during thyroid surgery. Observation: This narrative review (1) comprehensively reviews PG identification and vascular assessment using near-infrared autofluorescence (NIRAF) - both label free and in combination with indocyanine green - based on a comprehensive literature review and (2) offers a manual for possible implementation these emerging technologies in thyroid surgery. Conclusions and Relevance: Emerging technologies hold promise to improve PG identification and preservation during thyroidectomy. Future research should address variables affecting the degree of fluorescence in NIRAF, standardization of signal quantification, definitions and standardization of parameters of indocyanine green injection that correlate with postoperative PG function, the financial effect of these emerging technologies on near-term and longer-term costs, the adoption learning curve and effect on surgical training, and long-term outcomes of key quality metrics in adequately powered randomized clinical trials evaluating PG preservation.
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