Prior knowledge about events depicted in scenes decreases oculomotor exploration.

The visual input that the eyes receive usually contains temporally continuous information about unfolding events. Therefore, humans can accumulate knowledge about their current environment. Typical studies on scene perception, however, involve presenting multiple unrelated images and thereby render this accumulation unnecessary. Our study, instead, facilitated it and explored its effects. Specifically, we investigated how recently-accumulated prior knowledge affects gaze behavior. Participants viewed sequences of static film frames that contained several 'context frames' followed by a 'critical frame'. The context frames showed either events from which the situation depicted in the critical frame naturally followed, or events unrelated to this situation. Therefore, participants viewed identical critical frames while possessing prior knowledge that was either relevant or irrelevant to the frames' content. In the former case, participants' gaze behavior was slightly more exploratory, as revealed by seven gaze characteristics we analyzed. This result demonstrates that recently-gained prior knowledge reduces exploratory eye movements

Influence of prior knowledge on eye movements to scenes as revealed by hidden Markov models.

Human visual experience usually provides ample opportunity to accumulate knowledge about events unfolding in the environment. In typical scene perception experiments, however, participants view images that are unrelated to each other and, therefore, they cannot accumulate knowledge relevant to the upcoming visual input. Consequently, the influence of such knowledge on how this input is processed remains underexplored. Here, we investigated this influence in the context of gaze control. We used sequences of static film frames arranged in a way that allowed us to compare eye movements to identical frames between two groups: a group that accumulated prior knowledge relevant to the situations depicted in these frames and a group that did not. We used a machine learning approach based on hidden Markov models fitted to individual scanpaths to demonstrate that the gaze patterns from the two groups differed systematically and, thereby, showed that recently accumulated prior knowledge contributes to gaze control. Next, we leveraged the interpretability of hidden Markov models to characterize these differences. Additionally, we report two unexpected and interesting caveats of our approach. Overall, our results highlight the importance of recently acquired prior knowledge for oculomotor control and the potential of hidden Markov models as a tool for investigating it

Dendritic glycopolymers based on dendritic polyamine scaffolds: view on their synthetic approaches, characteristics and potential for biomedical applications

In this review we highlight the potential for biomedical applications of dendritic glycopolymers based on polyamine scaffolds. The complex interplay of the molecular characteristics of the dendritic architectures and their specific interactions with various (bio)molecules are elucidated with various examples. A special role of the individual sugar units attached to the dendritic scaffolds and their density is identified, which govern ionic and H-bond interactions, and biological targeting, but to a large extent are also responsible for the significantly reduced toxicity of the dendritic glycopolymers compared to their polyamine scaffolds. Thus, the application of dendritic glycopolymers in drug delivery systems for gene transfection but also as therapeutics in neurodegenerative diseases has great promisePublikacja w ramach programu Royal Society of Chemistry "Gold for Gold" 2014 finansowanego przez Uniwersytet Łódzk

Nanotechnology and the Treatment of HIV Infection

Suboptimal adherence, toxicity, drug resistance and viral reservoirs make the lifelong treatment of HIV infection challenging. The emerging field of nanotechnology may play an important role in addressing these challenges by creating drugs that possess pharmacological advantages arising out of unique phenomena that occur at the “nano” scale. At these dimensions, particles have physicochemical properties that are distinct from those of bulk materials or single molecules or atoms. In this review, basic concepts and terms in nanotechnology are defined, and examples are provided of how nanopharmaceuticals such as nanocrystals, nanocapsules, nanoparticles, solid lipid nanoparticles, nanocarriers, micelles, liposomes and dendrimers have been investigated as potential anti-HIV therapies. Such drugs may, for example, be used to optimize the pharmacological characteristics of known antiretrovirals, deliver anti-HIV nucleic acids into infected cells or achieve targeted delivery of antivirals to the immune system, brain or latent reservoirs. Also, nanopharmaceuticals themselves may possess anti-HIV activity. However several hurdles remain, including toxicity, unwanted biological interactions and the difficulty and cost of large-scale synthesis of nanopharmaceuticals

Effects of hospital facilities on patient outcomes after cancer surgery: an international, prospective, observational study

Background Early death after cancer surgery is higher in low-income and middle-income countries (LMICs) compared with in high-income countries, yet the impact of facility characteristics on early postoperative outcomes is unknown. The aim of this study was to examine the association between hospital infrastructure, resource availability, and processes on early outcomes after cancer surgery worldwide.Methods A multimethods analysis was performed as part of the GlobalSurg 3 study-a multicentre, international, prospective cohort study of patients who had surgery for breast, colorectal, or gastric cancer. The primary outcomes were 30-day mortality and 30-day major complication rates. Potentially beneficial hospital facilities were identified by variable selection to select those associated with 30-day mortality. Adjusted outcomes were determined using generalised estimating equations to account for patient characteristics and country-income group, with population stratification by hospital.Findings Between April 1, 2018, and April 23, 2019, facility-level data were collected for 9685 patients across 238 hospitals in 66 countries (91 hospitals in 20 high-income countries; 57 hospitals in 19 upper-middle-income countries; and 90 hospitals in 27 low-income to lower-middle-income countries). The availability of five hospital facilities was inversely associated with mortality: ultrasound, CT scanner, critical care unit, opioid analgesia, and oncologist. After adjustment for case-mix and country income group, hospitals with three or fewer of these facilities (62 hospitals, 1294 patients) had higher mortality compared with those with four or five (adjusted odds ratio [OR] 3.85 [95% CI 2.58-5.75]; p<0.0001), with excess mortality predominantly explained by a limited capacity to rescue following the development of major complications (63.0% vs 82.7%; OR 0.35 [0.23-0.53]; p<0.0001). Across LMICs, improvements in hospital facilities would prevent one to three deaths for every 100 patients undergoing surgery for cancer.Interpretation Hospitals with higher levels of infrastructure and resources have better outcomes after cancer surgery, independent of country income. Without urgent strengthening of hospital infrastructure and resources, the reductions in cancer-associated mortality associated with improved access will not be realised

The expectedness of semantic scene-content as a factor influencing human gaze behaviour

International audienceVisual information in the real world is typically continuous over time. In a pre-registered study, we investigated how this visual continuity influences eye movements, by comparing viewing behaviour when this continuity is preserved and when it is disrupted. Participants freely viewed 80 sequences of image frames from movies. Each sequence contained several ‘context’ frames followed by a ‘critical’ frame. Context frames were related and showed a consistent unfolding of events over time. The critical frame was either a natural continuation of these events (expected condition) or was completely unrelated to them (unexpected condition). We compared five characteristics of eye movements between the expected and unexpected conditions: number of fixations, saccade amplitude, mean fixation duration, probability of blinking and first-saccade latency. Results show that number of fixations and saccade amplitude increased in the unexpected condition relative to the expectedcondition whereas mean fixation duration and probability of blinking decreased. There was no significant effect for first-saccade latency. These findings suggest that how people look at identical scenes depends on the preceding temporal context, with participants displaying more exploratory visual behaviour and increased alertness when the current visual input is surprising (e.g. unexpected) in the context of precedingvisual images

Knowledge about the recent past affects human gaze patterns

International audienceHumans move their eyes to explore their surroundings, constantly changing the visual input they receive. Usually, the current visual input follows naturally from immediately preceding input. This temporal continuity of information enables the accumulation of knowledge about the environment. Here, we investigated how recently-gained knowledge influences gaze patterns and their underlying information-gathering strategy. Using eye tracking, we examined if people looked differently at natural scenes, depending on the presence or absence of relevant knowledge about the events immediately preceding the scenes. 48 Participants viewed 80 sequences of movie frames that comprised several ‘context’ frames showing an unfolding series of events, followed by a ‘critical’ frame. In an Expected condition, critical frames depicted natural continuations of events presented in the context frames. In an Unexpected condition, the context frames were unrelated to the critical frame. Importantly, critical frames were identical in both experimental conditions; only the context frames differed. We measured characteristics of gaze-patterns registered on the critical frames. Linear mixed-effects models analysis revealed that in the Unexpected condition, in comparison to the Expected, two measures increased (number of fixations and saccade length), two decreased (fixation duration and number of blinks; all p-values < 0.001), and one remained unaffected (first-saccade latency). These results indicate that without relevant knowledge about past events, oculomotor behavior is more exploratory. Next, we tested which information best differentiates the conditions. We fitted models which separate ‘spatial’ and ‘temporal’ information (hidden Markov models) to scan-paths from critical frames and used a machine-learning technique (linear discriminant analysis) to classify these models into two conditions. The classifier achieved 69% accuracy (chance-level: 50%). Crucially, discarding spatial, but not temporal, model-components substantially decreased the classifier’s performance, demonstrating that the conditions differ predominantly regarding sampled image-regions. In summary, we demonstrate that eye movements are influenced by information about the recent past