| 1. |
- Zuo, Nianming, et al.
(författare)
-
Activation-based association profiles differentiate network roles across cognitive loads
- 2019
-
Ingår i: Human Brain Mapping. - : Wiley. - 1065-9471 .- 1097-0193. ; 40:9, s. 2800-2812
-
Tidskriftsartikel (refereegranskat)abstract
- Working memory (WM) is a complex and pivotal cognitive system underlying the performance of many cognitive behaviors. Although individual differences in WM performance have previously been linked to the blood oxygenation level-dependent (BOLD) response across several large-scale brain networks, the unique and shared contributions of each large-scale brain network to efficient WM processes across different cognitive loads remain elusive. Using a WM paradigm and functional magnetic resonance imaging (fMRI) from the Human Connectome Project, we proposed a framework to assess the association and shared-association strength between imaging biomarkers and behavioral scales. Association strength is the capability of individual brain regions to modulate WM performance and shared-association strength measures how different regions share the capability of modulating performance. Under higher cognitive load (2-back), the frontoparietal executive control network (FPN), dorsal attention network (DAN), and salience network showed significant positive activation and positive associations, whereas the default mode network (DMN) showed the opposite pattern, namely, significant deactivation and negative associations. Comparing the different cognitive loads, the DMN and FPN showed predominant associations and globally shared-associations. When investigating the differences in association from lower to higher cognitive loads, the DAN demonstrated enhanced association strength and globally shared-associations, which were significantly greater than those of the other networks. This study characterized how brain regions individually and collaboratively support different cognitive loads.
|
|
| 2. |
- Fredriksson, Ida, et al.
(författare)
-
Orbitofrontal cortex and dorsal striatum functional connectivity predicts incubation of opioid craving after voluntary abstinence
- 2021
-
Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : NATL ACAD SCIENCES. - 0027-8424 .- 1091-6490. ; 118:43
-
Tidskriftsartikel (refereegranskat)abstract
- We recently introduced a rat model of incubation of opioid craving after voluntary abstinence induced by negative consequences of drug seeking. Here, we used resting-state functional MRI to determine whether longitudinal functional connectivity changes in orbitofrontal cortex (OFC) circuits predict incubation of opioid craving after voluntary abstinence. We trained rats to self-administer for 14 d either intravenous oxycodone or palatable food. After 3 d, we introduced an electric barrier for 12 d that caused cessation of reward self-administration. We tested the rats for oxycodone or food seeking under extinction conditions immediately after selfadministration training (early abstinence) and after electric barrier exposure (late abstinence). We imaged their brains before selfadministration and during early and late abstinence. We analyzed changes in OFC functional connectivity induced by reward selfadministration and electric barrier-induced abstinence. Oxycodone seeking was greater during late than early abstinence (incubation of oxycodone craving). Oxycodone self-administration experience increased OFC functional connectivity with dorsal striatum and related circuits that was positively correlated with incubated oxycodone seeking. In contrast, electric barrier-induced abstinence decreased OFC functional connectivity with dorsal striatum and related circuits that was negatively correlated with incubated oxycodone seeking. Food seeking was greater during early than late abstinence (abatement of food craving). Food self-administration experience and electric barrier-induced abstinence decreased or maintained functional connectivity in these circuits that were not correlated with abated food seeking. Opposing functional connectivity changes in OFC with dorsal striatum and related circuits induced by opioid self-administration versus voluntary abstinence predicted individual differences in incubation of opioid craving.
|
|
| 3. |
- Fredriksson, Ida, et al.
(författare)
-
Role of ventral subiculum neuronal ensembles in incubation of oxycodone craving after electric barrier-induced voluntary abstinence
- 2023
-
Ingår i: Science Advances. - : AMER ASSOC ADVANCEMENT SCIENCE. - 2375-2548. ; 9:2
-
Tidskriftsartikel (refereegranskat)abstract
- High relapse rate is a key feature of opioid addiction. In humans, abstinence is often voluntary due to negative consequences of opioid seeking. To mimic this human condition, we recently introduced a rat model of incubation of oxycodone craving after electric barrier-induced voluntary abstinence. Incubation of drug craving refers to time-dependent increases in drug seeking after cessation of drug self-administration. Here, we used the activity marker Fos, muscimol-baclofen (GABAa + GABAb receptor agonists) global inactivation, Daun020-selective inactivation of putative relapse-associated neuronal ensembles, and fluorescence-activated cell sorting of Fos-positive cells and quantitative polymerase chain reaction to demonstrate a key role of vSub neuronal ensembles in incubation of oxycodone craving after voluntary abstinence, but not homecage forced abstinence. We also used a longitudinal functional magnetic resonance imaging method and showed that functional connectivity changes in vSub-related circuits predict opioid relapse after abstinence induced by adverse consequences of opioid seeking.
|
|
| 4. |
- Hu, Junjie, et al.
(författare)
-
Flexibility Prediction of Aggregated Electric Vehicles and Domestic Hot Water Systems in Smart Grids
- 2021
-
Ingår i: Engineering. - : Elsevier BV. - 2095-8099. ; 7:8, s. 1101-1114
-
Tidskriftsartikel (refereegranskat)abstract
- With the growth of intermittent renewable energy generation in power grids, there is an increasing demand for controllable resources to be deployed to guarantee power quality and frequency stability. The flexibility of demand response (DR) resources has become a valuable solution to this problem. However, existing research indicates that problems on flexibility prediction of DR resources have not been investigated. This study applied the temporal convolution network (TCN)-combined transformer, a deep learning technique to predict the aggregated flexibility of two types of DR resources, that is, elec-tric vehicles (EVs) and domestic hot water system (DHWS). The prediction uses historical power con-sumption data of these DR resources and DR signals (DSs) to facilitate prediction. The prediction can generate the size and maintenance time of the aggregated flexibility. The accuracy of the flexibility pre-diction results was verified through simulations of case studies. The simulation results show that under different maintenance times, the size of the flexibility changed. The proposed DR resource flexibility pre-diction method demonstrates its application in unlocking the demand-side flexibility to provide a reserve to grids.
|
|
| 5. |
- Johnson, Jessica T.E., et al.
(författare)
-
In vivo disentanglement of diffusion frequency-dependence, tensor shape, and relaxation using multidimensional MRI
- 2024
-
Ingår i: Human Brain Mapping. - 1065-9471. ; 45:7
-
Tidskriftsartikel (refereegranskat)abstract
- Diffusion MRI with free gradient waveforms, combined with simultaneous relaxation encoding, referred to as multidimensional MRI (MD-MRI), offers microstructural specificity in complex biological tissue. This approach delivers intravoxel information about the microstructure, local chemical composition, and importantly, how these properties are coupled within heterogeneous tissue containing multiple microenvironments. Recent theoretical advances incorporated diffusion time dependency and integrated MD-MRI with concepts from oscillating gradients. This framework probes the diffusion frequency, (Formula presented.), in addition to the diffusion tensor, (Formula presented.), and relaxation, (Formula presented.), (Formula presented.), correlations. A (Formula presented.) clinical imaging protocol was then introduced, with limited brain coverage and 3 mm3 voxel size, which hinder brain segmentation and future cohort studies. In this study, we introduce an efficient, sparse in vivo MD-MRI acquisition protocol providing whole brain coverage at 2 mm3 voxel size. We demonstrate its feasibility and robustness using a well-defined phantom and repeated scans of five healthy individuals. Additionally, we test different denoising strategies to address the sparse nature of this protocol, and show that efficient MD-MRI encoding design demands a nuanced denoising approach. The MD-MRI framework provides rich information that allows resolving the diffusion frequency dependence into intravoxel components based on their (Formula presented.) distribution, enabling the creation of microstructure-specific maps in the human brain. Our results encourage the broader adoption and use of this new imaging approach for characterizing healthy and pathological tissues.
|
|
| 6. |
- Liwei, Wu, et al.
(författare)
-
Designing web-facilitated learning strategy guidance system : based on young learners' learning styles
- 2011
-
Ingår i: Interactive media use and youth. - : IGI Global. - 9781609602062 - 9781609602086 ; , s. 168-184
-
Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- This chapter elaborates on the research the authors engaged in for improving young learners learning competence and effectiveness. This research investigates learning styles and learning strategies, based on which comes up with principles, contents and activities for the design and development of a WebFacilitated Learning Strategy Guidance System (WFLSGS). A Quisi-Experiment is designed to test the function and implementation of WFLSGS and 3 distinctive findings comes out from the experiment: the research subjects' learning strategy level is generally low, thus learning strategies guidance is needed for improving learners learning effectiveness; the learning strategy guidance based on learning styles is effective for improving learning strategies, especially cognitive strategies and meta-cognitive strategies; the application of learning strategies is influenced by many factors such as teaching environment, learning content and learner self and so on. By designing and developing learning strategy guidance system, this study enriches the research of learning strategy and provides the teachers and young learners with operational advices and approaches to imporoving individualized learning competence and effectiveness.
|
|
| 7. |
- Yan, Shiyang, et al.
(författare)
-
Arch-related alteration in foot loading patterns affected by the increasing extent of body mass index in children : A follow-up study
- 2023
-
Ingår i: Gait & Posture. - : Elsevier BV. - 0966-6362 .- 1879-2219. ; 100, s. 247-253
-
Tidskriftsartikel (refereegranskat)abstract
- Background: A high load on children 's feet can cause arch deformation and negatively affect their normal development. Studies have yet to document how the foot arch varied with different body mass index (BMI) increments and its influence on foot loading patterns.Methods: Barefoot walking trails were conducted using a Footscan (R) plate system. A follow-up check was per-formed after twenty-four months. Participants were selected with an initial BMI between 14.5 kg/m2 and 16.5 kg/m2. Totally 75 participants were classified into groups 0-7 according to the BMI increment levels of 0-0.49 kg/m2, 0.50-1.49 kg/m2, 1.50-2.49 kg/m2, 2.50-3.49 kg/m2, 3.50-4.49 kg/m2, 4.50-5.49 kg/m2, 5.50-6.49 kg/m2, 6.50-7.49 kg/m2, respectively. Paired t-tests and effect sizes were used to compare the data.Results: The arch index significantly decreased when the BMI reached 20.8 kg/m2. Significantly increased normalized maximum forces were found in the great toe and 1st MTPJ in groups 4-5. Meanwhile, the absence of significance showed under the 3rd-5th, midfoot, and rearfoot in those groups. The normalized maximum force increments under the 3rd-5th MTPJs, midfoot and rearfoot regions in groups 4-5 after the follow-up study were significantly decreased compared with the increments found in groups 0-3, followed by a sudden increase arising under those regions in group 6. It indicates a transition period that leads to alteration in gait pattern charac-teristics when BMI increases to 18.6-19.9 kg/m2 (between group 3 and group 4). Group 6 displayed significantly increased peak pressure amplitudes under the great toe, 1st-3rd MTPJs, midfoot, and medial rearfoot compared to other groups.Significance: There was a transition period when the BMI of normal-weighted children increased to a certain extent and failed to reach the obesity level, resulting in changes in foot arch structure and loading patterns.
|
|
| 8. |
- Yang, Shubo, et al.
(författare)
-
Reconfigurable Intelligent Surface-induced Randomness for mmWave Key Generation
- 2023
-
Ingår i: ICC 2023. - : Institute of Electrical and Electronics Engineers Inc.. ; , s. 2909-2914
-
Konferensbidrag (refereegranskat)abstract
- Secret key generation in physical layer security exploits the unpredictable random nature of wireless channels. The millimeter-wave (mmWave) channels have limited multipath and channel randomness in static environments. In this paper, for mmWave secret key generation of physical layer security, we use a reconfigurable intelligent surface (RIS) to induce randomness directly in wireless environments, without adding complexity to transceivers. We consider RIS to have continuous individual phase shifts (CIPS) and derive the RIS-assisted reflection channel distribution with its parameters. Then, we propose continuous group phase shifts (CGPS) to increase the randomness specifically at legal parties. Since the continuous phase shifts are expensive to implement, we analyze discrete individual phase shifts (DIPS) and derive the corresponding channel distribution, which is dependent on the quantization bit. We then derive the secret key rate (SKR) to evaluate the randomness performance. With the simulation results verifying the analytical results, this work explains the mathematical principles and lays a foundation for future mmWave evaluation and optimization of artificial channel randomness.
|
|
| 9. |
- Yasar, Ozlen F., et al.
(författare)
-
The Carbonate and Sodium Environments in Precipitated and Biomimetic Calcium Hydroxy-Carbonate Apatite Contrasted with Bone Mineral : Structural Insights from Solid-State NMR
- 2021
-
Ingår i: The Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 125:19, s. 10572-10592
-
Tidskriftsartikel (refereegranskat)abstract
- Bone mineral consists of calcium hydroxy-carbonate apatite (HCA) that incorporates other minor cation substituents, primarily Na+ (0.5-0.8 wt %). We examine the carbonate species in various HCA specimens with variable CO32- contents (4-10 wt %), encompassing phases prepared by precipitation and a biomimetic specimen formed from a bioactive glass inside a simulated body fluid as well as bone tissue from beagle dog. Using magic-angle spinning (MAS) nuclear magnetic resonance (NMR) along with infrared spectroscopy experiments, we identified and quantified carbonate anions replacing either hydroxyl (A-type CO32-) or phosphate (B-type CO32-) anions in the HCA lattice, along with the carbonate species present in the amorphous surface layer present at all synthetic and biogenic nanocrystalline HCA particles. Advanced C-13-based NMR experimentation enabled the selective detection of the minor (CO32-)-C-13 population of intact bone monoliths, whose C-13 NMR signals are otherwise swamped by those from collagen, unless chemically invasive deproteination procedures are invoked. The CO32- species present in 4 week- and 8 month-old bone of the alveolar process from beagle dog revealed mainly B-type lattice sites and carbonates present in the amorphous surface layer. No tissue aging effects were observed in the local CO32- environments. Likewise, NMR revealed very similar Na-23(+) parameters in HCA, regardless of its synthetic or biogenic origin or degree of structural order. A combination of interatomic-distance-sensitive MAS NMR experiments allowed the identification of the local environments of the various carbonate, phosphate, hydroxyl, and water species present in both the interior and the surface layer of the synthetic HCA particles. We highlight the similarities/differences in the chemical speciation and the spatial distribution of CO32- anions present in carbonate-bearing amorphous calcium phosphate (ACP) relative to the ACP-like surface layer of HCA and discuss the C-13 NMR peak assignments of the up to four coexisting CO32- populations in the synthetic/biogenic HCA phases.
|
|
