40 research outputs found
Diffuse and Localized Functional Dysconnectivity in Schizophrenia: a Bootstrapped Top-Down Approach
No full textSchizophrenia (SZ) is a brain disorder leading to detached mind's normallyintegrated processes. Hence, the exploration of the symptoms in relation tofunctional connectivity (FC) had great relevance in the field. FC can beinvestigated on different levels, going from global features to single edgesbetween regions, revealing diffuse and localized dysconnection patterns. Inthis context, SZ is characterized by a diverse global integration with reducedconnectivity in specific areas of the Default Mode Network (DMN). However, theassessment of FC presents various sources of uncertainty. This study proposes amulti-level approach for more robust group-comparison. FC between 74 AAL brainareas of 15 healthy controls (HC) and 12 SZ subjects were used. Multi-levelanalyses and graph topological indexes evaluation were carried out by thepreviously published SPIDER-NET tool. Robustness was augmented by bootstrapped(BOOT) data and the stability was evaluated by removing one (RST1) or twosubjects (RST2). The DMN subgraph was evaluated, toegether with overall localindexes and connection weights to enhance common activations/deactivations. Ata global level, expected trends were found. The robustness assessment testshighlighted more stable results for BOOT compared to the direct data testing.Conversely, significant results were found in the analysis at lower levels. TheDMN highlighted reduced connectivity and strength as well as increaseddeactivation in the SZ group. At local level, 13 areas were found to besignificantly different (), highlighting a greater divergence in thefrontal lobe. These results were confirmed analyzing the negative edges,suggesting inverted connectivity between prefronto-temporal areas. Inconclusion, multi-level analysis supported by BOOT is highly recommended,especially when diffuse and localized dysconnections must be investigated inlimited samples.Comment: 28 pages, 8 figure
Diffuse and Localized Functional Dysconnectivity in Schizophrenia: a Bootstrapped Top-Down Approach
No full textSchizophrenia (SZ) is a brain disorder leading to detached mind's normally
integrated processes. Hence, the exploration of the symptoms in relation to
functional connectivity (FC) had great relevance in the field. FC can be
investigated on different levels, going from global features to single edges
between regions, revealing diffuse and localized dysconnection patterns. In
this context, SZ is characterized by a diverse global integration with reduced
connectivity in specific areas of the Default Mode Network (DMN). However, the
assessment of FC presents various sources of uncertainty. This study proposes a
multi-level approach for more robust group-comparison. FC between 74 AAL brain
areas of 15 healthy controls (HC) and 12 SZ subjects were used. Multi-level
analyses and graph topological indexes evaluation were carried out by the
previously published SPIDER-NET tool. Robustness was augmented by bootstrapped
(BOOT) data and the stability was evaluated by removing one (RST1) or two
subjects (RST2). The DMN subgraph was evaluated, toegether with overall local
indexes and connection weights to enhance common activations/deactivations. At
a global level, expected trends were found. The robustness assessment tests
highlighted more stable results for BOOT compared to the direct data testing.
Conversely, significant results were found in the analysis at lower levels. The
DMN highlighted reduced connectivity and strength as well as increased
deactivation in the SZ group. At local level, 13 areas were found to be
significantly different (), highlighting a greater divergence in the
frontal lobe. These results were confirmed analyzing the negative edges,
suggesting inverted connectivity between prefronto-temporal areas. In
conclusion, multi-level analysis supported by BOOT is highly recommended,
especially when diffuse and localized dysconnections must be investigated in
limited samples.Comment: 28 pages, 8 figure
Efficacy and safety of fentanyl HCl iontophoretic transdermal system compared with morphine intravenous patient-controlled analgesia for postoperative pain management for patient subgroups
No full textBackground and objective Inadequate postoperative pain control remains a problem for many patients undergoing surgery. This study presents subgroup analyses from a large, randomized, multicentre, European study comparing the efficacy and safety of the fentanyl HCl iontophoretic transdermal system and morphine intravenous patient-controlled analgesia for postoperative pain management. Methods The efficacy and safety of the fentanyl iontophoretic transdermal system and morphine intravenous patient-controlled analgesia were evaluated for patients divided by surgery type, sex, American Society of Anesthesiologists physical status and type of anaesthesia used during surgery. Efficacy measures included a patient global assessment of the method of pain control (a rating of 'good' or 'excellent' was considered as a success rating) and mean last pain intensity scores in the first 24 h. Discontinuation rates and the incidence of adverse events were also evaluated. Results Numerically similar percentages of patients in most subgroups reported success on the last patient global assessment in the first 24 h for both the fentanyl iontophoretic transdermal system and morphine intravenous patient-controlled analgesia. Similar percentages of investigators reported success ratings on the investigator global assessment at the last assessment for both treatment groups regardless of surgery type, except for the knee surgery subgroup (fentanyl iontophoretic transdermal system, 75%; morphine intravenous patient-controlled analgesia, 95%). Mean last pain intensity scores in the first 24 h after surgery were similar in all subgroups. Rates of patient withdrawals and the incidence of adverse events were generally similar between treatment groups in the patient subgroups. Conclusion The fentanyl iontophoretic transdermal system and morphine intravenous patient-controlled analgesia are comparably well tolerated and effective methods of pain control, regardless of sex, American Society of Anesthesiologists physical status or the type of anaesthesia used for surgery, and following most surgery types. Eur J Anaesthesiol 2010;27:433-44
Temperature, Atomic Oxigen and Outgassing effects on dielectric parameters and electrical properties of Nanostructured Camposite Carbon-based Materials.
No full textThis work deals with the dielectric properties of carbon-based nanostructured polymeric composite materials. A commercial epoxy matrix is currently filled with several species of carbon nanopowder in different percentages, and final composite material characterized in terms of microwave behavior by means of waveguide method. Following the guidelines of previous studies, the authors focus the attention on the changes induced by hard environmental conditions (high temperature in ultra high vacuum system) on the above mentioned properties. The results obtained in this preliminary research outline the intriguing properties of carbon nanostructures, establishing themselves as very promising materials for the future aerospace composite technology
Explainable AI Points to White Matter Hyperintensities for Alzheimer's Disease Identification: a Preliminary Study
No full textDeep Learning approaches are powerful tools in a great variety of classification tasks. However, they are limitedly accepted or trusted in clinical frameworks due to their typical "black box" outline: their architecture is well-known, but processes employed in classification are often inaccessible to humans. With this work, we explored the problem of "Explainable AI" (XAI) in Alzheimer's disease (AD) classification tasks. Data from a neuroimaging cohort (n = 251 from OASIS-3) of early-stage AD dementia and healthy controls (HC) were analysed. The MR scans were initially fed to a pre-trained DL model, which achieved good performance on the test set (AUC: 0.82, TPR: 0.78, TNR: 0.81). Results were then investigated by means of an XAI approach (Occlusion Sensitivity method) that provided measures of relevance (RV) as outcome. We compared RV values obtained within healthy tissues with those underlying white matter hyperintensity (WMH) lesions. The analysis was conducted on 4 different groups of data, obtained by stratifying correct and misclassified images according to the health condition of participants (AD/HC). Results highlighted that the DL model found favourable leveraging lesioned brain areas for AD identification. A statistically significant difference ( ) between WMH and healthy tissue contributions was indeed observed for AD recognition, differently from the HC case ( p=0.27). Clinical Relevance - This study, though preliminary, suggested that DL models might be trained to use known clinical information and reinforced the role of WMHs as neuroimaging biomarker for AD dementia. The outlined findings have a significant clinical relevance as they prepare the ground for a progressive increase in the level of trust laid in DL approaches
Low CTE waveguide for extreme thermal environment
No full textProbes are being sent towards extreme environments of our solar system. The delivery of the
science in these environments is a challenge for waveguide systems. The crucial aspects of the
design are associated with, and constrained by, the high-temperature, high-radiation exposure and
suitable conductivity, requiring advanced materials having a very low Coefficient of Thermal
Expansion (CTE). The combination of these requirements led to the selection of carbon-carbon as
an ideal material due to its low CTE, good strength, and excellent high temperature characteristics.
The purpose of this research was to investigate the feasibility of using carbon-carbon composite for
waveguide applications. The characterizations of the mechanical properties are determined through
several room temperature tests. A prototype rectangular tube-type assembly was fabricated and
copper was plated on the surface of the composite material as conducting surfaces. Specific
experiments aimed to study the electromagnetic and physical properties of the composite material
were performed. Particularly, the in plane and transverse CTE were examined to determine the
proper milling procedure and exploit material qualities. In addition, the machining direction was
essential to satisfy the dimensional stability specifications. Outgassing qualification of the
composite was analyzed and some coating solutions were also studied.
Prototype waveguide frequency range measurements and efficiency were tested to evaluate the
compatibility of C/C for waveguide applications
Temperature, atomic oxygen and outgassing effects on dielectric parameters and electrical properties of nanostructured composite carbon-based materials
No full textThis work deals with the dielectric properties of carbon-based nanostructured polymeric composite materials. A commercial epoxy matrix is currently filled with multiwalled carbon nanotubes, and final composite material characterized in terms of microwave behavior by means of the waveguide method.
By following the guidelines of previous studies, the attention is focused on the changes induced by hard environmental conditions (hightemperature in ultra-highvacuum system) on the above mentioned properties. The results obtained in this preliminary research have outlined the intriguing properties ofcarbon nanostructures, establishing themselves as verypromising materials for the future aerospace composite technolog
Development and Testing of {SPIDER}-{NET}: An Interactive Tool for Brain Connectogram Visualization, Sub-Network Exploration and Graph Metrics Quantification
No full textBrain connectomics consists in the modeling of human brain as networks, mathematically represented as numerical connectivity matrices. However, this representation may result in difficult interpretation of the data. To overcome this limitation, graphical representation by connectograms is currently used via open-source tools, which, however, lack user-friendly interfaces and options to explore specific sub-networks. In this context, we developed SPIDER-NET (Software Package Ideal for Deriving Enhanced Representations of brain NETworks), an easy-to-use, flexible, and interactive tool for connectograms generation and sub-network exploration. This study aims to present SPIDER-NET and to test its potential impact on pilot cases. As a working example, structural connectivity (SC) was investigated with SPIDER-NET in a group of 17 healthy controls (HCs) and in two subjects with stroke injury (Case 1 and Case 2, both with a focal lesion affecting part of the right frontal lobe, insular cortex and subcortical structures). 165 parcels were determined from individual structural magnetic resonance imaging data by using the Destrieux atlas, and defined as nodes. SC matrices were derived with Diffusion Tensor Imaging tractography. SC matrices of HCs were averaged to obtain a single group matrix. SC matrices were then used as input for SPIDER-NET. First, SPIDER-NET was used to derive the connectogram of the right hemisphere of Case 1 and Case 2. Then, a sub-network of interest (i.e., including gray matter regions affected by the stroke lesions) was interactively selected and the associated connectograms were derived for Case 1, Case 2 and HCs. Finally, graph-based metrics were derived for whole-brain SC matrices of Case 1, Case 2 and HCs. The software resulted effective in representing the expected (dis) connectivity pattern in the hemisphere affected by the stroke lesion in Cases 1 and 2. Furthermore, SPIDER-NET allowed to test an a priori hypothesis by interactively extracting a sub-network of interest: Case 1 showed a sub-network connectivity pattern different from Case 2, reflecting the different clinical severity. Global and local graph-based metrics derived with SPIDER-NET were different between cases with stroke injury and HCs. The tool proved to be accessible, intuitive, and interactive in brain connectivity investigation and provided both qualitative and quantitative evidence
Bariatric surgery does not affect kidney stone disease
No full textAbstract Background: numerous epidemiological studies demonstrate the correlation between obesity and urolithiasis. Bariatric surgery is effective in significant weight loss, reducing mortality rates, and lowering the incidence of obesity-related comorbidities. However, it may be associated with long-term complications such as urolithiasis, with an estimated increase of 7.6% in bariatric patients. This study investigates the impact of various bariatric surgical techniques and personal and nutritional habits on post-operative urolithiasis. Material and method: 185 patients were prospectively enrolled in the study. All patients underwent nutritional assessment two years after surgery, and urinary stone disease was evaluated through urinalysis. Patients with urinary crystals were subsequently sent to the division of Urology to evaluate the possible presence of urinary stones through an abdominal CT scan. Results: kidney stone disease was present in 12 female patients (12/ 185 − 6.49%) out of the 25 (12/25–48%) with urinary crystals. Among the various surgical techniques, 8 patients underwent SG, 2 patients each for OAGB and RYGB, without a proven significant correlation. Hypertension, Dyslipidemia, and OSAS were significantly correlated with the incidence of urolithiasis (p-value 30 kg/m2 was significantly correlated with urinary stone formation (p-value 30 kg/m2
