36 research outputs found
Einstein and Jordan frames reconciled: A frame-invariant approach to scalar-tensor cosmology
No full textScalar-tensor theories of gravity can be formulated in different frames, most notably, the Einstein and the Jordan one. While some debate still persists in the literature on the physical status of the different frames, a frame transformation in scalar-tensor theories amounts to a local redefinition of the metric, and then should not affect physical results. We analyze the issue in a cosmological context. In particular, we define all the relevant observables (redshift, distances, cross sections,...) in terms of frame-independent quantities. Then, we give a frame-independent formulation of the Boltzmann equation, and outline its use in relevant examples such as particle freeze-out and the evolution of the cosmic microwave background photon distribution function. Finally, we derive the gravitational equations for the frame-independent quantities at first order in perturbation theory. From a practical point of view, the present approach allows the simultaneous implementation of the good aspects of the two frames in a clear and straightforward way. © 2007 The American Physical Society
A Consistent High‐Resolution Catalog of Induced Seismicity in Basel Based on Matched Filter Detection and Tailored Post‐Processing
No full textSeismic monitoring of the Basel Enhanced Geothermal System has been running for more than a decade. Yet the details of the long-term behavior of its induced seismicity remained unexplored because a seismic event catalog with consistent detection sensitivity and magnitudes did not exist. This knowledge is essential for developing guidelines and mitigation procedures on how to safely operate and terminate injection activities. Only few observational data exist that cover all phases of such projects in a consistent manner. Here we describe a method that overcomes these deficiencies based on sensitive matched filter detection and a machine learning approach to remove false detections. With an emphasis on consistency, we create a catalog that contains more than 280,000 events down to M-w-1.5. The much higher temporal resolution allows us to analyze induced microearthquakes in great detail and to gain new insights. We resolved temporal variations of seismicity parameters and, in the post-operational phase, a preferential temporal clustering of events. We find a breakdown in the Gutenberg-Richter scaling during reservoir stimulation, which may have physical reasons or could be caused by a method-independent detection limit during high event rates. The scaling breakdown has implications for the design of Adaptive Traffic Light Systems and may limit the potential of real-time mitigation strategies in future Enhanced Geothermal System projects. Nevertheless, our catalog gives the opportunity to study the temporal evolution of the sequence in unprecedented detail, which will help to better understand the physical processes in a geothermal reservoir, potentially not only in the Basel case
"Non è solo una questione di colore!" L' africanità attraverso interazioni, pratiche e rappresentazioni sociali.
No full textThis research thesis focuses on the recent emergence of the “African-Italian” category of self- identification among young people in Italy with African origin. It explores how and to what extent the notion of Africanness is made and unmade, contested, reinterpreted and hyphenated in everyday practices, interactions and social representations. A common tendency shown by Italian-born youth with different African backgrounds is the increasing reference to Africa and African identity in cultural, social and entrepreneurial initiatives. This reveals their search for a new sense of their shared African heritage and at the same time a growing desire for public exposure and recognition of their Africanness.
Moreover, the multiple intersections of notions of Africanness, Blackness and Italianness in daily social interactions and in the local “politics of naming” shows that young people of African descent associate their “being African” with positioning themselves to local public debates about racism and in relation to transnational Blackness. Therefore, “being African” is not only an issue at the cultural and political levels, but it also represents a category of difference or belonging, which is an important matter for people in different relational contexts. Indeed, African-Italian youth politics of self-definition is situated at different spatial levels: the level of circulation of categories across the Black Atlantic, the European level of an increasing awareness of Afro-Europeanness, the national level of specific colonial histories and racial formations, and the local level of everyday interaction.
This PhD research aims at contributing to the emerging field of Afro-European studies in two ways. On the one hand it explores a specific South-European socio-historical context, Italy, on the other hand it proposes to approach Africanness and Blackness as categories of practices (Brubaker 2012). Firstly, the Italian specific colonial history together with the postcolonial African trajectories of migration and local integration consolidate the concept of alterity based on the colour of the skin as well as the “tribal clichés” on Africa and Africans. Both the social and historical elements have affected the evolution of the Italian-African diaspora, the racialization processes and the strategies to resist to racism. Secondly, this research intends to consider Africanness as an “identity of relation” (Glissant 1990) and a process of self-design (De Witte 2014). According to Palmié, in this research Africa and Africanness are not considered as analytical categories or ontological givens, but as “problems to be empirically investigated in regard to both the historical forces and discursive formations that lastingly 'Africanized' the continent and its inhabitants” (Palmié 2007). Therefore, understanding whether an element is authentically African becomes less important than explore, through social practices, interactions and socials representation, when and where the social actor claims his/ her Africanness or not (Chivallon 2004).
This research seeks to answer the following set of questions drawing on empirical data collected through ethnographic observations and narrative interviews. Who can be identified as an African? What does it entail to be a person with African origin in Italy and in Europe? When and to what extent does “being African” become (or cease to be) important? When does this dimension prevail over other levels of affiliations, i.e. national or ethnic, local or transnational? When is it contested? How does the notion of Africanness intersect with the notion of Blackness?
During the three-year project, the researcher collected 51 narrative gender-balanced interviews with young adults aged 20-35 with different national origins – i.e.⅓ from West Africa, ⅓ from East Africa, ⅓ from Central and South Africa- who were born or have lived in Italy for at least ten years. These interviewees are young professionals, entrepreneurs, artists, social activists or university students. They can be considered as young people with great aspirations, involved in a process of social mobility and who improve their skills and knowledge through education or self-entrepreneurship. In addition, the author has ethnographically observed relevant events dedicated to the whole African diaspora – i.e. beauty pageants, association meetings, trainings and other events – as well as family contexts and online conversations.
This methodology allowed to observe the elaboration of Africanness at different cultural and social levels. In the first part (ch.3) the research explored how Africanness emerges in social interactions within the Italian context, focusing on how this dimension appears as a category of alterity or as one of the aspects of the actors’ multiple identity, which is socially redefined and strategically used in daily life by the interviewees of this research. As a reaction to racism, young African-Italians appropriate the power to define what is African for themselves. This phenomenon challenges the “invention of Africa” (Mudimbe 1988), a notion relating Africanness to a paradigm of alterity. The transnational and diasporic levels of interactions carry a remarkable significance for social actors, allowing them to realize the instability of notions such as Blackness and Whiteness, as well as the process of “re-branding” Africa (De Witte 2014) occurring at the global level.
In the second part the research explored some corporeal practices: male circumcision (ch.4), haircare (ch.5), use of African textiles and accessories (ch.6). On the one hand, the Black body is the intersection of the social and historical experiences of youth in Africa and in the diaspora. On the other hand, the analysis of corporeal practices shows how social actors position themselves in relation to traditional habits and consolidated aesthetic styles. The making of Africanness is here explored as a process of self-design. The individual experience and definition of Africanness are embedded in the continuous tensions between intergenerational transmission, individual appropriation, performance and creativity. The exploration of practices that involve these dimensions of social and individual life - i.e. male circumcision, haircare, use of African textiles and accessories – elucidates how the meaning of “being African” changes within evolving biographies. It becomes therefore important for self-understanding but also in the processes of self-promotion.
In the last chapter (ch.7) this contribution underlined the interconnections between professional aspirations and the elaboration of Africanness. To face the lack of equal opportunities, African-Italian young people can capitalize the “African part” of their social networks or cultural backgrounds, allowing for new economic spaces and consumer niches.
Contested or celebrated, the appropriation of Africanness arises as an act “of self-making” and “of self-promotion” that reduces racial categories and discrimination practices to be regarded only as one of the aspects of social life. The research showed that African-Italian young people express their subjectivities in relation both to racial paradigms and to what is considered “the African heritage”. They therefore underline the versatility of their “being African”, which appears a social construction not to be strictly related to the skin, but to a reserve of symbols, aesthetic styles and cosmopolitan competences usable, also strategically, in different life stages and relational contexts
MALMI: An Automated Earthquake Detection and Location Workflow Based on Machine Learning and Waveform Migration
No full textRobust automatic event detection and location is central to real‐time earthquake monitoring. With the increase of computing power and data availability, automated workflows that utilize machine learning (ML) techniques have become increasingly popular; however, ML‐based classical workflows still face challenges when applied to the analysis of microseismic data. These seismic sequences are often characterized by short interevent times and/or low signal‐to‐noise ratio (SNR). Full waveform methods that do not rely on phase picking and association are suitable for processing such datasets, but are computationally costly and lack clear event identification criteria, which is not ideal for real‐time processing. To leverage the advantages of both the methods, we propose a new workflow—MAchine Learning aided earthquake MIgration location (MALMI), which integrates ML and waveform migration to perform automated event detection and location. The new workflow uses a pretrained ML model to generate continuous phase probabilities that are then backprojected and stacked to locate seismic sources using migration. We applied the workflow to one month of continuous data collected in the Hengill geothermal area of Iceland to monitor induced earthquakes around two geothermal production sites. With a ML model (EQ‐Transformer) pretrained using a global distribution of earthquakes, the proposed workflow automatically detects and locates 250 additional seismic events (accounting for 36% events in the obtained catalog) compared to a reference catalog generated using the SeisComP software. Most of the new events are microseismic events with a magnitude less than 0. Visual inspection of the waveforms of the newly detected events indicates that they are real seismic events of low SNR and are only reliably recorded by very few stations in the array. Further comparison with the conventional migration method based on short‐term average over long‐term average confirms that MALMI can produce much clearer stacked images with higher resolution and reliability, especially for events with low SNR. The workflow is freely available on GitHub, providing an automated tool for simultaneous event detection and location from continuous seismic data
Heart Rate Variability as a Tool for Seizure Prediction: A Scoping Review
No full text: The most critical burden for People with Epilepsy (PwE) is represented by seizures, the unpredictability of which severely impacts quality of life. The design of real-time warning systems that can detect or even predict ictal events would enhance seizure management, leading to high benefits for PwE and their caregivers. In the past, various research works highlighted that seizure onset is anticipated by significant changes in autonomic cardiac control, which can be assessed through heart rate variability (HRV). This manuscript conducted a scoping review of the literature analyzing HRV-based methods for detecting or predicting ictal events. An initial search on the PubMed database returned 402 papers, 72 of which met the inclusion criteria and were included in the review. These results suggest that seizure detection is more accurate in neonatal and pediatric patients due to more significant autonomic modifications during the ictal transitions. In addition, conventional metrics are often incapable of capturing cardiac autonomic variations and should be replaced with more advanced methodologies, considering non-linear HRV features and machine learning tools for processing them. Finally, studies investigating wearable systems for heart monitoring denoted how HRV constitutes an efficient biomarker for seizure detection in patients presenting significant alterations in autonomic cardiac control during ictal events
Salemme et al, Supplementary Fig and Tab-JAAD-D-21-02819R2
No full textSupplementary figures and table of the paper published on J Am Acad Dermatol 2022 by Salemme et al. Other contributors: Luca Fania, Alessandra Scarabello, Marzia Caproni, Angelo Valerio Marzano, Emanuele Cozzani. Claudio Feliciani, Clara De Simone, Manuela Papini, Rosanna Rita Satta, Aurora Parodi, Feliciana Mariotti, Stefania Lechiancole, Giovanni Genovese, Francesca Passarelli, Francesca Festa, Barbara Bellei, Alessia Provini, Donatella Sordi, Sabatino Pallotta, Damiano Abeni, Cinzia Mazzanti, Biagio Didona, Giovanni Di Zenzo.THIS DATASET IS ARCHIVED AT DANS/EASY, BUT NOT ACCESSIBLE HERE. TO VIEW A LIST OF FILES AND ACCESS THE FILES IN THIS DATASET CLICK ON THE DOI-LINK ABOV
A Context-Based Sustainability Maturity Model for the Medical Device Manufacturers
No full textSustainability is seen as the imperative strategy to implement to reach sustained competitive advantage. However, sustainability principles should be incorporated by all the organisations within an industry to reap real long-term benefits. The organisations are expected to rethink their processes from the pre-development phase until the end-of-life disposal of goods. This can be extremely complicated, especially for industries like the healthcare industry involving multiple stakeholders, a wide supply chain and producing technology for a very specific use. These are just some of the reasons why the healthcare industry lags behind other industry fields when it comes to sustainable development. Within the healthcare industry supply chain, the medical device manufacturers play the major role when it comes to determine the impacts medical systems have on ecosystem and society. Indeed, by providing innovative sustainable solutions they can contribute to social welfare, healthcare and environmental protection from degradation. Therefore, the scope of this research will be limited to explore the inter dependencies between the medical device manufacturers and sustainable development. To this end, a maturity model will be designed as a practical tool to assess the level of sustainability maturity of the medical device organisations’ supply chain. The maturity model will be designed in such a way to favour a better understanding of the concept of Sustainable Supply Chain Management, offering a detailed overview of sustainability aspects and bottom-line indicators. From the latter, a gap analysis will be performed and will support companies to spot areas for improvement and to set up maturation strategies
Pick- and waveform-based techniques for real-time detection of induced seismicity
No full textThe monitoring of induced seismicity is a common operation in many industrial activities, such as conventional and non-conventional hydrocarbon production or mining and geothermal energy exploitation, to cite a few. During such operations, we generally collect very large and strongly noise-contaminated data sets that require robust and automated analysis procedures. Induced seismicity data sets are often characterized by sequences of multiple events with short interevent times or overlapping events; in these cases, pick-based location methods may struggle to correctly assign picks to phases and events, and errors can lead to missed detections and/or reduced location resolution and incorrect magnitudes, which can have significant consequences if real-time seismicity information are used for risk assessment frameworks. To overcome these issues, different waveform-based methods for the detection and location of microseismicity have been proposed. The main advantages of waveform-based methods is that they appear to perform better and can simultaneously detect and locate seismic events providing high-quality locations in a single step, while the main disadvantage is that they are computationally expensive. Although these methods have been applied to different induced seismicity data sets, an extensive comparison with sophisticated pick-based detection methods is still missing. In this work, we introduce our improved waveform-based detector and we compare its performance with two pick-based detectors implemented within the SeiscomP3 software suite. We test the performance of these three approaches with both synthetic and real data sets related to the induced seismicity sequence at the deep geothermal project in the vicinity of the city of St. Gallen, Switzerland
swiss-seismological-service/scrtdd: v1.5.5
No full textrtDD is a SeisComP extension module that implements Double-Difference event relocation both in Real-Time, one event at the time, and classic offline mode, where an earthquake catalog is relocated as a whole
Predictive Value of Cardiac CTA, Cardiac MRI, and Transthoracic Echocardiography for Cardioembolic Stroke Recurrence
No full textBACKGROUND. Transthoracic echocardiography (TTE) is the standard of care for initial evaluation of patients with suspected cardioembolic stroke. Although TTE is useful for assessing certain sources of cardiac emboli, its diagnostic capability is limited in the detection of other sources, including left atrial thrombus and aortic plaques.OBJECTIVE. The purpose of this article was to investigate sensitivity, specificity, and predictive value of cardiac CTA (CCTA), cardiac MRI (CMRI), and TTE for recurrence in patients with suspected cardioembolic stroke.METHODS. We retrospectively included 151 patients with suspected cardioembolic stroke who underwent TTE and either CMRI (n = 75) or CCTA (n = 76) between January 2013 and May 2017. We evaluated for the presence of left atrial thrombus, left ventricular thrombus, vulnerable aortic plaque, cardiac tumors, and valvular vegetation as causes of cardioembolic stroke. The end point was stroke recurrence. Sensitivity, specificity, PPV, and NPV for recurrent stroke were calculated; the diagnostic accuracy of CMRI, CCTA, and TTE was compared between and within groups using AUC.RESULTS. Twelve and 14 recurrent strokes occurred in the CCTA and CMRI groups, respectively. Sensitivity, specificity, PPV, and NPV were 33.3%, 93.7%, 50.0%, and 88.2% for CCTA; 14.3%, 80.3%, 14.3%, and 80.3% for CMRI; 14.3%, 83.6%, 16.7%, and 80.9% for TTE in the CMRI group; and 8.3%, 93.7%, 20.0%, and 84.5% for TTE in the CCTA group. Accuracy was not different (p>.05) between CCTA (AUC = 0.63; 95% CI, 0.49-0.77), CMRI (0.53; 95% CI, 0.42-0.63), TTE in the CMRI group (0.51; 95% CI, 0.40-0.61), and TTE in the CCTA group (0.51; 95% CI, 0.42-0.59). In the CCTA group, atrial and ventricular thrombus were detected by CCTA in three patients and TTE in one patient; in the CMRI group, thrombus was detected by CMRI in one patient and TTE in two patients.CONCLUSION. CCTA, CMRI, and TTE showed comparably high specificity and NPV for cardioembolic stroke recurrence. CCTA and CMRI may be valid alternatives to TTE. CCTA may be preferred given potentially better detection of atrial and ventricular thrombus.CLINICAL IMPACT. CCTA and CMRI have similar clinical performance as TTE for predicting cardioembolic stroke recurrence. This observation may be especially important when TTE provides equivocal findings.</p
