2,134 research outputs found
Контактні лінзи: біохімічний, гістохімічний та мікробіологічний аспекти застосування
У статті на підставі аналізу зарубіжної та вітчизняної офтальмологічної літератури розглядається біохімічний, гістохімічний та мікробіологічний аспекти застосування контактних лінз
Tracking defect-induced ferromagnetism in GaN:Gd
We report on the magnetic properties of GaN:Gd layers grown by molecular beam
epitaxy (MBE). A poor reproducibility with respect to the magnetic properties
is found in these samples. Our results show strong indications that defects
with a concentration of the order of 10^19 cm^-3 might play an important role
for the magnetic properties. Positron annihilation spectroscopy does not
support the suggested connection between the ferromagnetism and the Ga vacancy
in GaN:Gd. Oxygen co-doping of GaN:Gd promotes ferromagnetism at room
temperature and points to a role of oxygen for mediating ferromagnetic
interactions in Gd doped GaN
Peer interaction does not always improve children's mental state talk production in oral narratives. A study in six- to ten-year-old Italian children
Joint narratives are a mean through which children develop and practice their Theory of Mind, thus they represent an ideal means to explore children’s use and development of mental state talk. However, creating a learning environment for storytelling based on peer interaction, does not necessarily mean that students will automatically exploit it by engaging in productive collaboration, thus it is important to explore under what conditions peer interaction promotes children’s ToM. This study extends our understanding of social aspects of ToM, focusing on the effect of joint narratives on school-age children’s mental state talk. Fifty-six Italian primary school children participated in the study (19 females and 37 males). Children created a story in two different experimental conditions (individually and with a partner randomly assigned). Each story told by the children, as well as their dialogues were recorded and transcribed. Transcriptions of narratives were coded in terms of text quality and mental state talk, whereas transcriptions of dialogues were coded in terms of quality of interaction. The results from this study confirmed that peer interaction does not always improve children’s mental state talk performances in oral narratives, but certain conditions need to be satisfied. Peer interaction was more effective on mental state talk with lower individual levels and productive interactions, particularly in terms of capacity to regulate the interactions. When children were able to focus on the interaction, as well as the product, they were also exposed to each other’s reasoning behind their viewpoint. This level of intersubjectivity, in turn, allowed them to take more in consideration the contribution of mental states to the narrative
Latent Dirichlet Allocation Uncovers Spectral Characteristics of Drought Stressed Plants
Understanding the adaptation process of plants to drought stress is essential
in improving management practices, breeding strategies as well as engineering
viable crops for a sustainable agriculture in the coming decades.
Hyper-spectral imaging provides a particularly promising approach to gain such
understanding since it allows to discover non-destructively spectral
characteristics of plants governed primarily by scattering and absorption
characteristics of the leaf internal structure and biochemical constituents.
Several drought stress indices have been derived using hyper-spectral imaging.
However, they are typically based on few hyper-spectral images only, rely on
interpretations of experts, and consider few wavelengths only. In this study,
we present the first data-driven approach to discovering spectral drought
stress indices, treating it as an unsupervised labeling problem at massive
scale. To make use of short range dependencies of spectral wavelengths, we
develop an online variational Bayes algorithm for latent Dirichlet allocation
with convolved Dirichlet regularizer. This approach scales to massive datasets
and, hence, provides a more objective complement to plant physiological
practices. The spectral topics found conform to plant physiological knowledge
and can be computed in a fraction of the time compared to existing LDA
approaches.Comment: Appears in Proceedings of the Twenty-Eighth Conference on Uncertainty
in Artificial Intelligence (UAI2012
A Software-defined SoC Memory Bus Bridge Architecture for Disaggregated Computing
Disaggregation and rack-scale systems have the potential of drastically
decreasing TCO and increasing utilization of cloud datacenters, while
maintaining performance. While the concept of organising resources in separate
pools and interconnecting them together on demand is straightforward, its
materialisation can be radically different in terms of performance and scale
potential.
In this paper, we present a memory bus bridge architecture which enables
communication between 100s of masters and slaves in todays complex
multiprocessor SoCs, that are physically intregrated in different chips and
even different mainboards. The bridge tightly couples serial transceivers and a
circuit network for chip-to-chip transfers. A key property of the proposed
bridge architecture is that it is software-defined and thus can be configured
at runtime, via a software control plane, to prepare and steer memory access
transactions to remote slaves. This is particularly important because it
enables datacenter orchestration tools to manage the disaggregated resource
allocation. Moreover, we evaluate a bridge prototype we have build for ARM AXI4
memory bus interconnect and we discuss application-level observed performance.Comment: 3rd International Workshop on Advanced Interconnect Solutions and
Technologies for Emerging Computing Systems (AISTECS 2018, part of HiPEAC
2018
Predicting reading and spelling disorders: a 4-year prospective cohort study
In this 4-year prospective cohort study, children with a reading and spelling disorder, children with a spelling impairment, and children without a reading and/or spelling disorder (control group) in a transparent orthography were identified in third grade, and their emergent literacy performances in kindergarten compared retrospectively. 642 Italian children participated. This cohort was followed from the last year of kindergarten to third grade. In kindergarten, the children were assessed in phonological awareness, conceptual knowledge of writing systems and textual competence. In third grade, 18 children with a reading and spelling impairment and 13 children with a spelling impairment were identified. Overall, conceptual knowledge of the writing system was the only statistically significant predictor of the clinical samples. No differences were found between the two clinical samples
Many-Core Architectures: Hardware-Software Optimization and Modeling Techniques
During the last few decades an unprecedented technological growth has been at the center of the embedded systems design paramount, with Moore’s Law being the leading factor of this trend. Today in fact an ever increasing number of cores can be integrated on the same die, marking the transition from state-of-the-art multi-core chips to the new many-core design paradigm. Despite the extraordinarily high computing power, the complexity of many-core chips opens the door to several challenges. As a result of the increased silicon density of modern Systems-on-a-Chip (SoC), the design space exploration needed to find the best design has exploded and hardware designers are in fact facing the problem of a huge design space. Virtual Platforms have always been used to enable hardware-software co-design, but today they are facing with the huge complexity of both hardware and software systems. In this thesis two different research works on Virtual Platforms are presented: the first one is intended for the hardware developer, to easily allow complex cycle accurate simulations of many-core SoCs. The second work exploits the parallel computing power of off-the-shelf General Purpose Graphics Processing Units (GPGPUs), with the goal of an increased simulation speed. The term Virtualization can be used in the context of many-core systems not only to refer to the aforementioned hardware emulation tools (Virtual Platforms), but also for two other main purposes: 1) to help the programmer to achieve the maximum possible performance of an application, by hiding the complexity of the underlying hardware. 2) to efficiently exploit the high parallel hardware of many-core chips in environments with multiple active Virtual Machines. This thesis is focused on virtualization techniques with the goal to mitigate, and overtake when possible, some of the challenges introduced by the many-core design paradigm
Evolution of Bat-Trypanosome Associations and the Origins of Chagas Disease
Trypanosoma cruzi is a genetically diverse parasite that causes Chagas disease, one of the most important zoonoses in the Americas. This generalist parasite of mammals belongs to a clade mostly comprised of bat parasites, the T. cruzi clade. The origins (i.e., biogeographic history and evolution of hosts associations) of this parasite are far from being understood, and the main areas that need further study are: species limits within T. cruzi sensu lato, further studies on the diversity of T. cruzi clade members and their hosts, and research on adaptations of the hosts to trypanosome infections. In this dissertation I explore these research areas in five core chapters (Ch.2 to Ch.6), and these are the main results per chapter: ch.2) Proposed the recognition of Tcbat as a major diagnostic typing unit of T. cruzi. Ch.3) Found high genetic diversity in the bat exclusive lineage T. c. marinkellei than in the other subdivisions of T. cruzi. Also, reported Tcbat and T. c. marinkellei for Ecuador. Ch.4) Determined that the number of putative species in the T. cruzi clade is underestimated, and more strikingly, that the bat Artibeus jamaicensis is the vertebrate host with the highest number of trypanosomes (5 species) detected in a single locality. Ch.5) Results indicate that T. cruzi sensu lato is actually comprised of three species - the generalist T. cruzi, and two parasites of bats, Trypanosoma marinkellei and Trypanosoma sp. nov.; that there is a previously undetected high diversity of T. cruzi relatives associated with bats, and use of bats as hosts has evolved several times and in three different clades of parasites. Ch.6) Tested the hypothesis that immune genes in bats evolve under stronger positive selection than in other mammals because of the high diversity of pathogens associated with bats--including trypanosomes of the T. cruzi clade. I used the gene TLR2, as a candidate gene. These results help to understanding better the diversity of the T. cruzi clade, and the importance of bats on the origins of T. cruzi sensu strict and Chagas disease
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