105 research outputs found
The physics of angular momentum radio
Wireless communications, radio astronomy and other radio science applications
are predominantly implemented with techniques built on top of the
electromagnetic linear momentum (Poynting vector) physical layer. As a
supplement and/or alternative to this conventional approach, techniques rooted
in the electromagnetic angular momentum physical layer have been advocated, and
promising results from proof-of-concept radio communication experiments using
angular momentum were recently published. This sparingly exploited physical
observable describes the rotational (spinning and orbiting) physical properties
of the electromagnetic fields and the rotational dynamics of the pertinent
charge and current densities. In order to facilitate the exploitation of
angular momentum techniques in real-world implementations, we present a
systematic, comprehensive theoretical review of the fundamental physical
properties of electromagnetic angular momentum observable. Starting from an
overview that puts it into its physical context among the other Poincar\'e
invariants of the electromagnetic field, we describe the multi-mode quantized
character and other physical properties that sets electromagnetic angular
momentum apart from the electromagnetic linear momentum. These properties
allow, among other things, a more flexible and efficient utilization of the
radio frequency spectrum. Implementation aspects are discussed and illustrated
by examples based on analytic and numerical solutions.Comment: Fixed LaTeX rendering errors due to inconsistencies between arXiv's
LaTeX machine and texlive in OpenSuSE 13.
Differential Epigenetic Changes in the Dorsal Hippocampus of Male and Female SAMP8 Mice: A Preliminary Study
Alzheimer’s disease (AD) is the most common age-related neurodegenerative disease characterized by memory loss and cognitive impairment. The causes of the disease are not well understood, as it involves a complex interaction between genetic, environmental, and epigenetic factors. SAMP8 mice have been proposed as a model for studying late-onset AD, since they show age-related learning and memory deficits as well as several features of AD pathogenesis. Epigenetic changes have been described in SAMP8 mice, although sex differences have never been evaluated. Here we used western blot and qPCR analyses to investigate whether epigenetic markers are differentially altered in the dorsal hippocampus, a region important for the regulation of learning and memory, of 9-month-old male and female SAMP8 mice. We found that H3Ac was selectively reduced in male SAMP8 mice compared to male SAMR1 control mice, but not in female mice, whereas H3K27me3 was reduced overall in SAMP8 mice. Moreover, the levels of HDAC2 and JmjD3 were increased, whereas the levels of HDAC4 and Dnmt3a were reduced in SAMP8 mice compared to SAMR1. In addition, levels of HDAC1 were reduced, whereas Utx and Jmjd3 were selectively increased in females compared to males. Although our results are preliminary, they suggest that epigenetic mechanisms in the dorsal hippocampus are differentially regulated in male and female SAMP8 mice
The Terracol and Ardouin developmental model of frontal sinus drainage pathway and surrounding spaces: a radiologic validation
The complexity of the frontal sinus drainage pathway (FSDP) can be challenging even for expert surgeons. Several classifications have been proposed to simplify the understanding of FSDP, whose anatomical variability can be simplified based on the knowledge of its developmental mechanisms
The frontoethmoidal architecture: a developmental point of view
The anatomy of frontal sinus drainage pathway (FSDP) and surrounding spaces is extremely complex and variable. Its anatomical variability can be simplified based on the knowledge of the developmental mechanism of the frontal recess. The frontal sinus develops from the 13th week of intrauterine life to the age of twenty through a number of well-known steps of progressive extension within the frontal bone. Its development results from an upward epithelial migration of the anterior ethmoidal cells that penetrate the inferior aspect of the frontal bone between its two diploic plates. Even though this developmental theory is almost universally accepted, only few Authors focused on the formation of FSDP prior to the extramural pneumatization (1-2). The results of the present study conducted on 14 human heads match with the developmental model proposed by Terracol and Ardouin (2), in fact a number of significant associations are conform to the process of growing of the frontal sinus from one out of the three primordial cells (i.e. orbital, nasal, or bullar cell). In this model, renewed in view of the observation of the present study, the hierarchical order of growing among primordial cells determines the final frontoethmoidal architecture
Evaluation of state-of-the-art segmentation algorithms for left ventricle infarct from late Gadolinium enhancement MR images
Studies have demonstrated the feasibility of late Gadolinium enhancement (LGE) cardiovascular magnetic
resonance (CMR) imaging for guiding the management of patients with sequelae to myocardial infarction,
such as ventricular tachycardia and heart failure. Clinical implementation of these developments necessitates
a reproducible and reliable segmentation of the infarcted regions. It is challenging to compare
new algorithms for infarct segmentation in the left ventricle (LV) with existing algorithms. Benchmarking
datasets with evaluation strategies are much needed to facilitate comparison. This manuscript presents
a benchmarking evaluation framework for future algorithms that segment infarct from LGE CMR of the
LV. The image database consists of 30 LGE CMR images of both humans and pigs that were acquired
from two separate imaging centres. A consensus ground truth was obtained for all data using maximum
likelihood estimation.
Six widely-used fixed-thresholding methods and five recently developed algorithms are tested on the
benchmarking framework. Results demonstrate that the algorithms have better overlap with the consensus
ground truth than most of the n-SD fixed-thresholding methods, with the exception of the FullWidth-at-Half-Maximum
(FWHM) fixed-thresholding method. Some of the pitfalls of fixed thresholding
methods are demonstrated in this work. The benchmarking evaluation framework, which is a contribution
of this work, can be used to test and benchmark future algorithms that detect and quantify infarct
in LGE CMR images of the LV. The datasets, ground truth and evaluation code have been made publicly
available through the website: https://www.cardiacatlas.org/web/guest/challenges
Activation of locus coeruleus heme oxygenase-carbon monoxide pathway promoted an anxiolytic-like effect in rats
Rapid automatic segmentation of abnormal tissue in late gadolinium enhancement cardiovascular magnetic resonance images for improved management of long-standing persistent atrial fibrillation
Background: Atrial fibrillation (AF) is the most common heart rhythm disorder. In order for late Gd enhancement cardiovascular magnetic resonance (LGE CMR) to ameliorate the AF management, the ready availability of the accurate enhancement segmentation is required. However, the computer-aided segmentation of enhancement in LGE CMR of AF is still an open question. Additionally, the number of centres that have reported successful application of LGE CMR to guide clinical AF strategies remains low, while the debate on LGE CMR’s diagnostic ability for AF still holds. The aim of this study is to propose a method that reliably distinguishes enhanced (abnormal) from non-enhanced (healthy) tissue within the left atrial wall of (pre-ablation and 3 months post-ablation) LGE CMR data-sets from long-standing persistent AF patients studied at our centre.
Methods: Enhancement segmentation was achieved by employing thresholds benchmarked against the statistics of the whole left atrial blood-pool (LABP). The test-set cross-validation mechanism was applied to determine the input feature representation and algorithm that best predict enhancement threshold levels.
Results: Global normalized intensity threshold levels T PRE = 1 1/4 and T POST = 1 5/8 were found to segment enhancement in data-sets acquired pre-ablation and at 3 months post-ablation, respectively. The segmentation results were corroborated by using visual inspection of LGE CMR brightness levels and one endocardial bipolar voltage map. The measured extent of pre-ablation fibrosis fell within the normal range for the specific arrhythmia phenotype. 3D volume renderings of segmented post-ablation enhancement emulated the expected ablation lesion patterns. By comparing our technique with other related approaches that proposed different threshold levels (although they also relied on reference regions from within the LABP) for segmenting enhancement in LGE CMR data-sets of AF patients, we illustrated that the cut-off levels employed by other centres may not be usable for clinical studies performed in our centre.
Conclusions: The proposed technique has great potential for successful employment in the AF management within our centre. It provides a highly desirable validation of the LGE CMR technique for AF studies. Inter-centre differences in the CMR acquisition protocol and image analysis strategy inevitably impede the selection of a universally optimal algorithm for segmentation of enhancement in AF studies
Percorso diagnostico, terapeutico e assistenziale per i tumori di testa e collo – Aggiornamento 2020 AIOCC
Didactic and Pedagogical View of E-learning Activities Free University of Bozen-bolzano
In the knowledge and communication age, the contribution of technology, especially web 2.0, has transformed the concept of distance learning into that of e-learning and online learning. These are based on the use of CSCL (Computer Supported Collaborative Learning) and characterised by a pedagogical approach focussed on the learner, cooperative building of knowledge, and increasing the diversity of its learner base. Online learning represents a considerable opportunity for universities to promote larger and more democratic access to intellectual resources, reducing the social gap that is often related to on-site learning. However, using e-learning educational methods require careful consideration of different aspects and problems. This paper starts with a description of the most widely used open source e-learning platforms in Italian Universities. Furthermore, it proposes an analysis of the pedagogical and didactic potential of the tools offered by the Moodle platform and a reflection about the need to use guidelines to evaluate accessibility, also with reference to the Universal Instructional Design principles. In the final part, a study about the concrete use of specific Moodle activities in some courses at the University of Bolzano (empirical research and verification on field) is presented with the purpose of identifying methodological indications that could help to implement the educational and inclusive value of the online contexts
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