University of Fribourg

About: University of Fribourg is a education organization based out in Fribourg, Freiburg, Switzerland. It is known for research contribution in the topics: Population & Context (language use). The organization has 6040 authors who have published 14975 publications receiving 542500 citations. The organization is also known as: UNIFR & Universität Freiburg.

Laser spectroscopy of muonic deuterium

Abstract: The deuteron is the simplest compound nucleus, composed of one proton and one neutron. Deuteron properties such as the root-mean-square charge radius r d and the polarizability serve as important benchmarks for understanding the nuclear forces and structure. Muonic deuterium μd is the exotic atom formed by a deuteron and a negative muon μ – . We measured three 2S-2P transitions in μd and obtain r d = 2.12562 ( 78 ) fm, which is 2.7 times more accurate but 7.5σ smaller than the CODATA-2010 value r d = 2.1424 ( 21 ) fm. The μd value is also 3.5σ smaller than the r d value from electronic deuterium spectroscopy. The smaller r d , when combined with the electronic isotope shift, yields a “small” proton radius r p , similar to the one from muonic hydrogen, amplifying the proton radius puzzle.

Participatory Cultural Mapping Based on Collective Behavior Data in Location-Based Social Networks

Abstract: Culture has been recognized as a driving impetus for human development. It co-evolves with both human belief and behavior. When studying culture, Cultural Mapping is a crucial tool to visualize different aspects of culture (e.g., religions and languages) from the perspectives of indigenous and local people. Existing cultural mapping approaches usually rely on large-scale survey data with respect to human beliefs, such as moral values. However, such a data collection method not only incurs a significant cost of both human resources and time, but also fails to capture human behavior, which massively reflects cultural information. In addition, it is practically difficult to collect large-scale human behavior data. Fortunately, with the recent boom in Location-Based Social Networks (LBSNs), a considerable number of users report their activities in LBSNs in a participatory manner, which provides us with an unprecedented opportunity to study large-scale user behavioral data. In this article, we propose a participatory cultural mapping approach based on collective behavior in LBSNs. First, we collect the participatory sensed user behavioral data from LBSNs. Second, since only local users are eligible for cultural mapping, we propose a progressive “home” location identification method to filter out ineligible users. Third, by extracting three key cultural features from daily activity, mobility, and linguistic perspectives, respectively, we propose a cultural clustering method to discover cultural clusters. Finally, we visualize the cultural clusters on the world map. Based on a real-world LBSN dataset, we experimentally validate our approach by conducting both qualitative and quantitative analysis on the generated cultural maps. The results show that our approach can subtly capture cultural features and generate representative cultural maps that correspond well with traditional cultural maps based on survey data.

Structural and functional definition of the motor cortex in the monkey (Macaca fascicularis)

Abstract: 1. The details of the organization of the motor cortex and its anterior and posterior border were investigated in three monkeys by a combination of techniques including intracortical microstimulation (i.c.m.s.), electrophysiological recording of cutaneous and muscle afferent inputs to single cortical neurones, and electrophysiological and anatomical identification of corticospinal neurones; in addition, data from these methods were related to cortical cytoarchitecture. 2. Almost 5000 individual cortical loci were tested with i.c.m.s. in the unanaesthetized monkeys. In this paper, we particularly consider the organization of the forelimb motor representation, and its relation to the representation of other parts of the body. I.c.m.s. thresholds of about 5 μA were common for evoking twitch movements and e.m.g. responses in distal forelimb and face, jaw and tongue muscles, but proximal forelimb, trunk and hind-limb movements also sometimes had such low thresholds. 3. The fingers were found to be represented nearest the central sulcus, with horseshoe-shaped bands of cortical tissue representing progressively more proximal muscles situated around this central `finger core'. 4. Cytoarchitectonically, the cortex having these low-threshold motor effects was characteristic of area 4. There was also a close fit between the extent of this `excitable cortex' and the extent of densely spaced corticospinal neurones identified electro-physiologically or with horseradish peroxidase labelling. In subsequent mapping of forelimb afferents to the cortex when the animal was deeply anaesthetized, low-threshold and short-latency responses to muscle nerve stimulation were rarely found in this `excitable cortex'. 5. The anterior border could be clearly established by i.c.m.s. and by the sharp boundary of corticospinal neurones. It was noted that the motor cortex extends rostrally beyond area 4 and its anterior border appears to reside in the posterior part of area 6aα (Vogt & Vogt, 1919) although it is difficult to establish the precise transition from area 4 to area 6. 6. Posteriorly, the `micro-excitable cortex' was found to be limited to regions cytoarchitectonically delineated as area 4 and did not include area 3a. On the other hand, low-threshold forelimb proprioceptive afferent inputs appeared restricted to area 3a neurones in the deeply anaesthetized animal. Corticospinal neurones were very dense in area 4, and there was a clear decrease in their occurrence in more caudal areas. However, scattered nests of corticospinal neurones were noted in areas 3a, 3b, 2, 1 and 5. It remains to be seen whether these scattered nests could be directly involved in motor control or whether they may modulate ascending somatosensory transmission, and whether they rely on sensory feed-back or inputs from other central areas for their spinal effects.

Recurrent knowledge graph embedding for effective recommendation

Abstract: Knowledge graphs (KGs) have proven to be effective to improve recommendation. Existing methods mainly rely on hand-engineered features from KGs (e.g., meta paths), which requires domain knowledge. This paper presents RKGE, a KG embedding approach that automatically learns semantic representations of both entities and paths between entities for characterizing user preferences towards items. Specifically, RKGE employs a novel recurrent network architecture that contains a batch of recurrent networks to model the semantics of paths linking a same entity pair, which are seamlessly fused into recommendation. It further employs a pooling operator to discriminate the saliency of different paths in characterizing user preferences towards items. Extensive validation on real-world datasets shows the superiority of RKGE against state-of-the-art methods. Furthermore, we show that RKGE provides meaningful explanations for recommendation results.