| 1. |
- Johansson, Roger, et al.
(författare)
-
Neurocognitive bases for the functional role of gaze direction during episodic memory retrieval
- 2018
-
Konferensbidrag (refereegranskat)abstract
- Previous research has established that when engaged in episodic memory retrieval, people frequently look at locations associated with the sought-after memory trace, even if those locations no longer contain any information. While it has been further demonstrated that gaze positions showing compatibility between encoding and retrieval increase the likelihood of successful remembering (Johansson & Johansson, 2014), virtually nothing is known about the neurocognitive bases subserving this “looking at nothing” effect. The present study combined electroencephalography (EEG) and eye-tracking to investigate oscillatory brain activity for 30 participants who retrieved information from a previously encoded spatial arrangement of objects. Critically, participants were directed to fixate on a location of a blank screen, where the location was either congruent or incongruent with the original encoding location of the to-be-retrieved object. The results replicate previous findings, by showing superior episodic memory performance when looking at a congruent location, and further demonstrate that this facilitatory effect of gaze direction is associated with increased cortical desynchronization in the alpha/beta-band. Such desynchronization of oscillatory power in the alpha/beta band is considered to reflect successful encoding and retrieval of an episodes’ sensory information (e.g., Hanslmayr, Staresina, & Bowman, 2016). Gaze direction showing compatibility between encoding and retrieval would thus increase the specificity of neural reactivation and ultimately increase the likelihood of successful remembering. To our knowledge, this is the first causal evidence that gaze direction is functionally relevant for cortical reconstruction during episodic remembering.
|
|
| 2. |
- Johansson, Roger, et al.
(författare)
-
Pupil dilation tracks the dynamics of mnemonic interference resolution
- 2018
-
Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 8
-
Tidskriftsartikel (refereegranskat)abstract
- Mnemonic interference refers to the inability to retrieve a goal-relevant memory due to interference from goal-irrelevant memories. Understanding the causes of such interference and how it is overcome has been a central goal in the science of memory for more than a century. Here, we shed new light on this fundamental issue by tracking participants’ pupil response when they encode and retrieve memories in the face of competing goal-irrelevant memories. We show that pupil dilation systematically increased in accordance with interference from competing memory traces when participants retrieved previously learned information. Moreover, our results dissociate two main components in the pupillary response signal: an early component, which peaked in a time window where the pupillary waveform on average had its maximum peak, and a late component, which peaked towards the end of the retrieval task. We provide evidence that the early component is specifically modulated by the cognitive effort needed to handle interference from competing memory traces whereas the late component reflects general task engagement. This is the first demonstration that mnemonic interference resolution can be tracked online in the pupil signal and offers novel insight into the underlying dynamics.
|
|
| 3. |
|
|
| 4. |
- Chang, C. W. Sandbo, et al.
(författare)
-
Generating Multimode Entangled Microwaves with a Superconducting Parametric Cavity
- 2018
-
Ingår i: Physical Review Applied. - 2331-7019. ; 10:4
-
Tidskriftsartikel (refereegranskat)abstract
- We demonstrate the generation of multimode entangled states of propagating microwaves. The entangled states are generated by our parametrically pumping a multimode superconducting cavity. By combining different pump frequencies, applied simultaneously to the device, we can produce different entanglement structures in a programable fashion. The Gaussian output states are fully characterized by our measuring the full covariance matrices of the modes. The covariance matrices are absolutely calibrated by our using an in situ microwave calibration source, a shot-noise tunnel junction. Applying a variety of entanglement measures, we demonstrate both full inseparability and genuine tripartite entanglement of the states. Our method is easily extensible to more modes.
|
|
| 5. |
- Dewhurst, Richard, et al.
(författare)
-
How task demands influence scanpath similarity in a sequential number-search task
- 2018
-
Ingår i: Vision Research. - : Elsevier BV. - 1878-5646 .- 0042-6989. ; , s. 9-23
-
Tidskriftsartikel (refereegranskat)abstract
- More and more researchers are considering the omnibus eye movement sequence—the scanpath—in their studies of visual and cognitive processing (e.g. Hayes, Petrov, & Sederberg, 2011; Madsen, Larson, Loschky, & Rebello, 2012; Ni et al., 2011; von der Malsburg & Vasishth, 2011). However, it remains unclear how recent methods for comparing scanpaths perform in experiments producing variable scanpaths, and whether these methods supplement more traditional analyses of individual oculomotor statistics. We address this problem for MultiMatch (Jarodzka et al., 2010; Dewhurst et al., 2012), evaluating its performance with a visual search-like task in which participants must fixate a series of target numbers in a prescribed order. This task should produce predictable sequences of fixations and thus provide a testing ground for scanpath measures. Task difficulty was manipulated by making the targets more or less visible through changes in font and the presence of distractors or visual noise. These changes in task demands led to slower search and more fixations. Importantly, they also resulted in a reduction in the between-subjects scanpath similarity, demonstrating that participants’ gaze patterns became more heterogenous in terms of saccade length and angle, and fixation position. This implies a divergent strategy or random component to eye-movement behaviour which increases as the task becomes more difficult. Interestingly, the duration of fixations along aligned vectors showed the opposite pattern, becoming more similar between observers in 2 of the 3 difficulty manipulations. This provides important information for vision scientists who may wish to use scanpath metrics to quantify variations in gaze across a spectrum of perceptual and cognitive tasks. © 2018 Elsevier Ltd
|
|
| 6. |
- Freiburghaus, Catja, et al.
(författare)
-
Bortezomib prevents cytarabine resistance in MCL, which is characterized by down-regulation of dCK and up-regulation of SPIB resulting in high NF-κB activity
- 2018
-
Ingår i: BMC Cancer. - : Springer Science and Business Media LLC. - 1471-2407. ; 18:1
-
Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: The addition of high-dose cytarabine to the treatment of mantle cell lymphoma (MCL) has significantly prolonged survival of patients, but relapses are common and are normally associated with increased resistance. To elucidate the mechanisms responsible for cytarabine resistance, and to create a tool for drug discovery investigations, we established a unique and molecularly reproducible cytarabine resistant model from the Z138 MCL cell line.METHODS: Effects of different substances on cytarabine-sensitive and resistant cells were evaluated by assessment of cell proliferation using [methyl-14C]-thymidine incorporation and molecular changes were investigated by protein and gene expression analyses.RESULTS: Gene expression profiling revealed that major transcriptional changes occur during the initial phase of adaptation to cellular growth in cytarabine containing media, and only few key genes, including SPIB, are deregulated upon the later development of resistance. Resistance was shown to be mediated by down-regulation of the deoxycytidine kinase (dCK) protein, responsible for activation of nucleoside analogue prodrugs. This key event, emphasized by cross-resistance to other nucleoside analogues, did not only effect resistance but also levels of SPIB and NF-κB, as assessed through forced overexpression in resistant cells. Thus, for the first time we show that regulation of drug resistance through prevention of conversion of pro-drug into active drug are closely linked to increased proliferation and resistance to apoptosis in MCL. Using drug libraries, we identify several substances with growth reducing effect on cytarabine resistant cells. We further hypothesized that co-treatment with bortezomib could prevent resistance development. This was confirmed and show that the dCK levels are retained upon co-treatment, indicating a clinical use for bortezomib treatment in combination with cytarabine to avoid development of resistance. The possibility to predict cytarabine resistance in diagnostic samples was assessed, but analysis show that a majority of patients have moderate to high expression of dCK at diagnosis, corresponding well to the initial clinical response to cytarabine treatment.CONCLUSION: We show that cytarabine resistance potentially can be avoided or at least delayed through co-treatment with bortezomib, and that down-regulation of dCK and up-regulation of SPIB and NF-κB are the main molecular events driving cytarabine resistance development.
|
|
| 7. |
- Iversen, Kia Noehr, 1987, et al.
(författare)
-
Appetite and Subsequent Food Intake Were Unaffected by the Amount of Sourdough and Rye in Soft Bread-A Randomized Cross-Over Breakfast Study
- 2018
-
Ingår i: Nutrients. - : MDPI AG. - 2072-6643 .- 2072-6643. ; 10:11
-
Tidskriftsartikel (refereegranskat)abstract
- Sourdough fermented bread has been suggested to have beneficial health effects, in part mediated by increased satiety in the postprandial phase, but only limited research has been conducted to verify this. The current study aimed to investigate the effect of the amounts of sourdough and rye in soft bread on postprandial appetite. On 6 occasions, 23 healthy volunteers consumed 5 different test breads, with varying amount of rye and sourdough, and a yeast-fermented refined wheat control bread as part of a breakfast meal. The sourdough ranged between 9⁻51% of dough weight and rye content between 35⁻48% of flour weight. Appetite was recorded using visual analogue scales from immediately before breakfast and every 30 min the following 4 h. An ad libitum lunch was served 4 h after the breakfast meal, from which voluntary energy intake was measured. While some of the test breads resulted in lower hunger ratings and increased sense of fullness compared to the refined wheat bread, there were no differences between the test breads. The content of rye in the test breads differed within a narrow range, which might explain the lack of a consistent effect of rye on appetite. Microstructural examination of the test breads showed an increased aggregation of proteins in the breads with high content of sourdough, indicating additional changes to the breads, beyond change in pH, which may counteract the potential effect of decreased pH in the bread on appetite. In conclusion, our study does not support an effect of sourdough on appetite and ad libitum food intake.
|
|
| 8. |
- Jakobsson, Anders, et al.
(författare)
-
Teachers’ Reflections on Science Instruction as a Language Activity
- 2018
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Several researchers have characterized the use of language in science instruction as a 3-language problem, as the students move between home-, school-, and scientific languages and expressions. In this way it is possible to describe a science classroom as an arena for several discursive or hybrid languages where different expressions are negotiated and discussed. The 3-language problem has highlighted the importance of making hybrid spaces explicit for students by comparing and merging their everyday worlds and colloquial language with the languages of science. An important question is what language and discursive awareness science teachers express about how science communication in different contexts may constitute a hindrance or support for students’ engagement in science? We explore in what ways 10 science teachers reflect upon different communicative and language perspectives in science education in Sweden. The participating teachers work half time as teachers in primary and secondary school and attend a part time graduate school in education at the university. Interviews focused on experienced possibilities and difficulties when discussing science and technology with their students. Preliminary results suggest a general lack of or an implicit discursive awareness among teachers about science instruction as a language activity. However, several teachers exemplified new ways of outlining and forming contemporary scientific and technological knowledge for students.
|
|
| 9. |
- Jansson, John-Olov, 1954, et al.
(författare)
-
Body weight homeostat that regulates fat mass independently of leptin in rats and mice.
- 2018
-
Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 1091-6490. ; 115:2, s. 427-432
-
Tidskriftsartikel (refereegranskat)abstract
- Subjects spending much time sitting have increased risk of obesity but the mechanism for the antiobesity effect of standing is unknown. We hypothesized that there is a homeostatic regulation of body weight. We demonstrate that increased loading of rodents, achieved using capsules with different weights implanted in the abdomen or s.c. on the back, reversibly decreases the biological body weight via reduced food intake. Importantly, loading relieves diet-induced obesity and improves glucose tolerance. The identified homeostat for body weight regulates body fat mass independently of fat-derived leptin, revealing two independent negative feedback systems for fat mass regulation. It is known that osteocytes can sense changes in bone strain. In this study, the body weight-reducing effect of increased loading was lost in mice depleted of osteocytes. We propose that increased body weight activates a sensor dependent on osteocytes of the weight-bearing bones. This induces an afferent signal, which reduces body weight. These findings demonstrate a leptin-independent body weight homeostat ("gravitostat") that regulates fat mass.
|
|
| 10. |
- Jiang, Roger
(författare)
-
Overcoming the Mass Transport Limitations of Dye-Sensitised Solar Cells : Towards highly efficient and robust alternative redox mediator electrolyte DSSCs
- 2018
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Dye-sensitised solar cells (DSSCs) have been subject to decadelong research interest, and may have some potential niche market applications. Recently, major advances in power conversion efficiencies have been achieved following the transition to cobalt polypyridine based redox mediators. Unfortunately, these champion devices remained unfeasible for commercialisation due to heavy reliance on flammable volatile acetonitrile electrolytes. Overcoming this issue has been a challenge due to increased mass transport limitations, which are especially exacerbated in more stable albeit viscous electrolytes. The overall aim of this thesis is to better understand the contributing factors to mass transport, and then to develop practical solutions to overcome these limitations. In particular, specific mass transport limitations pertaining to the bulk electrolyte medium and electrolyte-infiltrated TiO2 medium, are investigated. The effect of non-uniform photogeneration profile across the photoanode is explored with respect to mass transport using photocurrent transient techniques. Practical devices engineering for optimal mass transport is explored in terms of minimising the inter-electrode spacing and maximising light absorption towards the electrolyte-electrode side. Alternative devices based on more practical electrolytes with higher viscosity are optimised for high efficiency.
|
|
