77 research outputs found
Super-resolution imaging of glutamate receptors in cultured hippocampal neurons under basal and LTP conditions
Get PDFThe locations and dynamics of glutamate synaptic receptors—the AMPA receptors (AMPARs) and NMDA receptors (NMDARs)—located on the postsynaptic membrane of nerve cells, are crucial for neuronal health, learning and memory formation. They can exist under basal condition where no synaptic strength change occurs, and chemically induced long-term potentiation (cLTP) condition, where synaptic strength is increased by activation of NMDARs from glycine that triggers changes in the number and structure of AMPARs. With three-dimensional super-resolution microscopy (7~16 nm resolution in x-y and 20~32 nm resolution in z), we study AMPARs and NMDARs under basal and cLTP conditions.
Under basal condition, we compare two different size fluorophores attached to AMPAR or NMDAR: one is big quantum dots (bQDs), ~20 nm in diameter, which are widely used in the literature; the other is organic dyes, which together with its necessary binding protein, are ~ 4 nm in diameter. We find that organic dyes are superior to bQDs because organic dyes have better access to synapses, which itself is only 20-25 nm across, due to their smaller size. Our results with organics dyes (particularly, Atto647N) are shown to be different than the prevailing results based on bQDs. AMPARs are found to be mostly constrained in the synaptic region, which contradicts the ‘slots’ hypothesis using bQDs. NMDARs, however, are found in both synaptic and extrasynaptic regions. The ratio of synaptic/extrasynaptic population of the two NMDAR subunits (GluN2A and GluN2B) are found to be very different. This ratio is known to be significant in neuronal function/dysfunction. We also quantified this ratio during the maturation process and find redistribution of the synaptic/extrasynaptic NMDARs.
Next, cLTP is induced. During this process, the activation of NMDARs is known to cause changes in number and structure of AMPAR on the postsynaptic membrane. In particular, the AMPAR subunits GluA1 and GluA2 are known to contribute to cLTP, but a quantitative understanding is missing in terms of the AMPAR insertion sites on the postsynaptic membrane; how AMPARs move after insertion; and if there are structural changes of AMPARs upon cLTP. We tracked the newly inserted AMPARs and find both synaptic and extrasynaptic insertion sites at 5 and 20 min after cLTP. The portion of synaptic AMPAR increases from 5 to 20 min (32% to 50%). Correspondingly, we also find an increase in synaptic AMPAR numbers. This is done by determining the number of AMPARs under basal condition and the number of the newly inserted ones at 5 and 20 min after cLTP. Taking GluA1-type AMPAR at 5 min after cLTP as an example, under basal conditions, there are 31.8±1.7 synaptic GluA1 on the membrane; when cLTP is induced, 8.1±0.23 internal AMPARs exocytose to the membrane: that is 22.1% ± 1.3% more synaptic GluA1 compared to basal level. Repeating the same method at 20 min after cLTP gives 28.9% ± 1.4% more synaptic GluA1 compared to basal level. This means there is a 7% (out of 22%) increase in synaptic GluA1 from 5 to 20 min. We determine that this occurs because of synaptic exocytosis, not the widely believed lateral diffusion. The conclusion for GluA2 is the same. Aside from the number change, we also observe the structure change of AMPAR during cLTP. We find a ~1.6x increase in AMPAR channel currents from 5 min to 20 min after cLTP. What structure change would cause this is unclear, but it is possible due to desensitization.Submission published under a 24 month embargo labeled 'U of I Access', the embargo will last until 2021-08-01The student, Chaoyi Jin, accepted the attached license on 2019-06-28 at 14:15.The student, Chaoyi Jin, submitted this Dissertation for approval on 2019-06-28 at 14:28.This Dissertation was approved for publication on 2019-07-01 at 11:09.DSpace SAF Submission Ingestion Package generated from Vireo submission #14109 on 2019-11-26 at 13:04:01Made available in DSpace on 2019-11-26T20:49:17Z (GMT). No. of bitstreams: 2
JIN-DISSERTATION-2019.pdf: 2574560 bytes, checksum: 7331d674e18035d9e0959523b1839203 (MD5)
LICENSE.txt: 4207 bytes, checksum: da9750cc32ffc055803e1e5987748bcb (MD5)
Previous issue date: 2019-07-01Embargo set by: Seth Robbins for item 112916
Lift date: 2021-11-26T20:49:41Z
Reason: Author requested U of Illinois access only (OA after 2yrs) in Vireo ETD systemU of I Only Restriction Lifted for Item 112916 on 2021-11-27T10:15:16Z
Client self-defense against model poisoning in federated learning
No full textFederated Learning is highly susceptible to backdoor and targeted attacks as participants can manipulate their data and models locally without any oversight on whether they follow the correct process. There are a number of server-side defenses that mitigate the attacks by modifying or rejecting local updates submitted by clients. However, we find that bursty adversarial patterns with a high variance in the number of malicious clients can circumvent the existing defenses. We propose a client-self defense, LeadFL, that is combined with existing server-side defenses to thwart backdoor and targeted attacks. The core idea of LeadFL is a novel regularization term in local model training such that the Hessian matrix of local gradients is nullified. We provide the convergence analysis of LeadFL and its robustness guarantee in terms of certified radius. Our empirical evaluation shows that LeadFL is able to mitigate bursty adversarial patterns for both iid and non-iid data distributions. It frequently reduces the backdoor accuracy from more than 75% for state-of-the-art defenses to less than 10% while its impact on the main task accuracy is always less than for other client-side defenses.Computer Scienc
An Investigation into In-Store Customer Experience and Its Influence on Purchasing Intention of Male Chinese Luxury Fashion Consumers
Get PDFChina has become the most attractive luxury fashion product market, in which male consumers were major segment in luxury fashion products consumption, and luxury fashion products consumption mainly took place in retail stores. Meanwhile, experience marketing has dynamically developed. This encouraged researchers to focus on how to understand, improve and utilize customer experience in marketing activities, especially marketing of physical retail stores. Although it has captured the attention of scholars and practitioners, there still were not many related studies.
Based on the consideration, by referring to the results of existing researches, this study conducted a quantitative study to identify in-store customer experience and its influence on the purchasing intention of male Chinese luxury fashion consumers. In-store customer experience was measured with four dimensions, namely, cognitive experience, affective experience, social experience and physical experience. In this study, this author first conducted a literature review to summarise and critically evaluate existing academic findings on customer experience, purchasing intention, luxury fashion and Chinese luxury fashion market. Second, this author explained the methodology of this study. Under a quantitative approach, data about in-store customer experience and purchasing intention of male Chinese luxury consumers was collected through a questionnaire based on Likert scales. After correlation analysis and multiple regression analysis, it was found that cognitive experience, affective experience, social experience, physical experience, and overall in-store experience all had a positive influence on purchasing intention. Moreover, among them, physical experience and social experience were two stronger predictors of purchasing intention, whereas cognitive experience and affective experience were relatively weak predictors. Finally, implications for practitioners were proposed
An Investigation into In-Store Customer Experience and Its Influence on Purchasing Intention of Male Chinese Luxury Fashion Consumers
No full textChina has become the most attractive luxury fashion product market, in which male consumers were major segment in luxury fashion products consumption, and luxury fashion products consumption mainly took place in retail stores. Meanwhile, experience marketing has dynamically developed. This encouraged researchers to focus on how to understand, improve and utilize customer experience in marketing activities, especially marketing of physical retail stores. Although it has captured the attention of scholars and practitioners, there still were not many related studies.
Based on the consideration, by referring to the results of existing researches, this study conducted a quantitative study to identify in-store customer experience and its influence on the purchasing intention of male Chinese luxury fashion consumers. In-store customer experience was measured with four dimensions, namely, cognitive experience, affective experience, social experience and physical experience. In this study, this author first conducted a literature review to summarise and critically evaluate existing academic findings on customer experience, purchasing intention, luxury fashion and Chinese luxury fashion market. Second, this author explained the methodology of this study. Under a quantitative approach, data about in-store customer experience and purchasing intention of male Chinese luxury consumers was collected through a questionnaire based on Likert scales. After correlation analysis and multiple regression analysis, it was found that cognitive experience, affective experience, social experience, physical experience, and overall in-store experience all had a positive influence on purchasing intention. Moreover, among them, physical experience and social experience were two stronger predictors of purchasing intention, whereas cognitive experience and affective experience were relatively weak predictors. Finally, implications for practitioners were proposed
A rare case of renal angiomyolipoma involved both inferior vena cava and pulmonary arteries
No full textCenter–surround interaction with adaptive inhibition: A computational model for contour detection
No full textDecoupled Tracking Control for a Flexible Multi-body Satellite with Solar Panels and Manipulator
No full textThis paper studies the tracking control of a robotic manipulator mounted on a rigid satellite with flexible solar panels. By designing a decoupled feedback controller, the manipulator can track planned paths in the presence of the disturbances from the flexural modes of the panels, and meanwhile, the attitude dynamics of the satellite are stabilized. Stability analysis is proposed based on the Floquet theory for periodic linear systems. Finally, numerical simulations are carried out to validate the controller for the nonlinear model.NSFC [61273111]; National Basic Research Program of China (973 Program) [2012CB821200]CPCI-S(ISTP)[email protected]
The syntax and semantics of headless relative clauses
No full textHeadless relative clauses exhibit dual characteristics: morphologically, they resemble clauses, while distributionally, they function as nouns, adjectives, or adverbs. This dual nature complicates a comprehensive understanding of their syntactic and semantic properties. This dissertation advances our understanding of headless relative clauses by addressing four syntactic and semantic issues. First, I examine the syntactic transformation of nominal headless relatives from CPs to NPs/DPs. Through a detailed cross-linguistic investigation, I propose that this transformation requires a categorical [N]/[D] feature provided by the daughters of the headless-relative node. In [+wh] headless relatives, overt fronted wh-phrases supply the [N]/[D] feature, whereas in [-wh] headless relatives, external nominal heads can provide this feature. Next, I explore whether all arguments within a headless relative clause can be equally relativized when they are phonologically null. A preference for the object reading over the subject reading is observed in Mandarin doubly-gapped headless relatives. I argue that this asymmetry stems from a general preference for nested movements over crossing movements, as well as the unavailability of generic null objects with most Mandarin verbs. I then turn to the semantic composition of headless relative clauses. I observe that pied-pipings in English free relatives are in general degraded. Based on this observation, I propose a compositional analysis where the meaning of free relatives is sensitive to the form of their fronted strings. Finally, I extend the discussion to the readings headless relatives can have and their parallels with modified bare nouns. Drawing on the similarities between English free relatives and modified bare nouns, I argue that the distribution of kind and non-kind readings in these two constructions should be captured in a unified manner. Additionally, I discuss how their non-kind readings differ in terms of maximality.Ph.D.Includes bibliographical reference
A water-soluble iridium complex: Highly sensitive to bisulfite and sequential recognition to Cu 2+ ions
No full textContour detection based on a non-classical receptive field model with butterfly-shaped inhibition subregions
No full text- …
