144 research outputs found
A deep learning integrated Lee-Carter model
In the field of mortality, the Lee–Carter based approach can be considered the milestone
to forecast mortality rates among stochastic models. We could define a “Lee–Carter model family”
that embraces all developments of this model, including its first formulation (1992) that remains the
benchmark for comparing the performance of future models. In the Lee–Carter model, the kt parameter,
describing the mortality trend over time, plays an important role about the future mortality behavior.
The traditional ARIMA process usually used to model kt shows evident limitations to describe the future
mortality shape. Concerning forecasting phase, academics should approach a more plausible way in
order to think a nonlinear shape of the projected mortality rates. Therefore, we propose an alternative
approach the ARIMA processes based on a deep learning technique. More precisely, in order to catch
the pattern of kt series over time more accurately, we apply a Recurrent Neural Network with a Long
Short-Term Memory architecture and integrate the Lee–Carter model to improve its predictive capacity.
The proposed approach provides significant performance in terms of predictive accuracy and also allow
for avoiding the time-chunks’ a priori selection. Indeed, it is a common practice among academics to
delete the time in which the noise is overflowing or the data quality is insufficient. The strength of
the Long Short-Term Memory network lies in its ability to treat this noise and adequately reproduce it
into the forecasted trend, due to its own architecture enabling to take into account significant long-term
patterns
Vaccine Hesitancy: Lessons Learned and Perspectives for a Post-Pandemic Tomorrow
Infectious diseases have always posed a significant threat to mankind, resulting in high mortality and morbidity throughout history [1]. Currently, the burden of communicable diseases still remains very high in all age groups worldwide [2]. Moreover, the current COVID-19 pandemic has once again underlined the tremendous impact of transmittable diseases in terms of public health [1].
From this point of view, vaccines have always represented a fundamental public health tool. Indeed, mass immunization campaigns save millions of lives each year [3]. Furthermore, COVID-19 vaccines are enabling us to overcome the ongoing pandemic. Therefore, it is of utmost importance to promote vaccine uptake and to identify and address barriers for achieving adequate vaccination coverage.
Among the obstacles to reaching adequate vaccination coverage, vaccine hesitancy (VH) is rightfully included.
VH is defined by SAGE working group as “the delay in acceptance or refusal of vaccination despite the availability of vaccination services”[4] and was included by the World Health Organization (WHO) amongst the major health concerns in 2019 [5]. Going into detail, VH appears to be complex and context specific, varying across time, place and types of vaccines [4]. All these factors have been studied with respect to VH in recent decades and have played a big role during the COVID-19 pandemic and will certainly continue to do so in the post-pandemic future
Nano-engineered adhesive biomaterials for biomedical applications
This thesis is focused on the development of adhesive systems for biomedical applications and has been carried out in the framework of the European Project \u201cAnastomoSEAL\u201d (EU-FP7). Within this project, a bioactive membrane based on polysaccharides was developed for the prevention of anastomotic leakage (AL) after colo-rectal cancer (CRC) resection. The membrane was designed to be wrapped around the intestinal tissue in order to stimulate the healing of the surgical wound, thus accelerating its closure. The main components of the system were the two polysaccharides alginate and hyaluronan (HA), the former representing the physical matrix, the latter exerting a bioactive function in the terms of stimulating the healing of wounds. The main goals of this thesis were to manufacture and characterize the membranes and to design tissue-adhesives that could be implemented in the medical device. In the first part of the work, the procedure for the membrane preparation was set up, followed by the characterization of the product as to its mechanical, chemical and biological properties. The membranes were prepared by freeze-drying alginate-HA hydrogels crosslinked by calcium ions (Ca2+). Several formulations of the membrane were screened to tailor its performance in the terms of mechanical resistance, stiffness and deformation. In vitro biological test pointed out the the non-cytotoxicity of the membranes, as well as the ability of the released HA to stimulate the healing of fibroblasts. Degradation tests and release studies were performed to predict the in vivo behavior of the membrane, pointing out that, in simulated physiological conditions, the release of HA occurs during the first hours, whereas a complete degradation of the membrane is achieved in 21 days. Sterilized membranes were also characterized to investigate the effect of terminal sterilization on the membrane properties; in particular, the effect of supercritical carbon dioxide (scCO2) supplemented with H2O2 was studied. In parallel, adhesive strategies were designed and tailored to the peculiar features of both membrane and intestinal tissue.
The adhesive strategies developed in this thesis were based either on the use of exogenous compounds (i.e. H2O2), or on the use of molecules displaying bioadhesive properties. In the first case, adhesion studies proved the enhancement of the adhesion strength between membrane and tissue after the treatment with H2O2, and pointed out the ability of this compound to induce the formation of an adhesive interface made of gelatin, which was integrated in the structure of the tissue. In the latter case, bio-inspired adhesive strategies were designed considering the adhesion mechanism employed by natural organisms (i.e. mussels). The key adhesive molecules of mussel\u2019s adhesive (i.e. catechol-based compounds) were implemented into the structure of the membrane by chemical modifications. In vitro adhesion tests showed an improved adhesion of the modified-membrane in simulated physiological conditions, which was confirmed in vivo by preliminary adhesion studies.
A second mussel-inspired adhesive strategy was based on the development of nanoparticles displaying a catecholic core, named melanin-like nanoparticles (MNPs). MNPs were characterized from a biological point of view and used to prepared adhesive coatings for the AnastomoSEAL membrane, whose adhesive properties were evaluated by in vitro adhesion tests. In conclusion, the tests performed allowed the development of a medical device endowed with adhesive components that enabled an efficient adhesion in a physiological environment
Deep Learning Forecasting for Supporting Terminal Operators in Port Business Development
Accurate forecasts of containerised freight volumes are unquestionably important for port terminal operators to organise port operations and develop business plans. They are also relevant for port authorities, regulators, and governmental agencies dealing with transportation. In a time when deep learning is in the limelight, owing to a consistent strip of success stories, it is natural to apply it to the tasks of forecasting container throughput. Given the number of options, practitioners can benefit from the lessons learned in applying deep learning models to the problem. Coherently, in this work, we devise a number of multivariate predictive models based on deep learning, analysing and assessing their performance to identify the architecture and set of hyperparameters that prove to be better suited to the task, also comparing the quality of the forecasts with seasonal autoregressive integrated moving average models. Furthermore, an innovative representation of seasonality is given by means of an embedding layer that produces a mapping in a latent space, with the parameters of such mapping being tuned using the quality of the predictions. Finally, we present some managerial implications, also putting into evidence the research limitations and future opportunities
Natural plant extracts as active components in chitosan-based films: A comparative study
Chitosan-based films with separately incorporated plant extracts obtained from oak (Quercus robur), hop (Humulus lupulus), and brown algae (Laminaria hyperborea) were evaluated and mutually compared regarding structural, physicochemical, and antibacterial properties. Processing of chitosan and extracted raw substances led to the development of blended films with diverse physical appearances and physicochemical properties. Starting from the oak extract-containing film and ending with the algal extract-containing film, blended films shown ascending trends in moisture content (21.5% – 28.3%), total soluble matter (23.8% – 28.9%), and elongation at break (14.0% – 31.0%) as well as descending trends in tensile strength (12.7 MPa – 5.5 MPa), Young’s modulus (230.8 MPa – 19.4 MPa), and total phenolic content (9.1 mgGAE gfilm⁻¹ – 1.0 mgGAE gfilm⁻¹). The films loaded with oak and hop extracts had improved optical properties reflected in the ability to completely block the light transmittance at the wavelengths below ∼330 nm. Moreover, the same films exhibited the appearance of inhibition zones implying the antibacterial activity against Bacillus subtilis
Social innovation during turbulent times: a systematic literature review and research agenda
Contemporary societies are affected by profound and often disruptive changes leading to socio-economic turbulence. The COVID-19 pandemic has been one of such changes. Gaining a deeper understanding of how society-based responses – such as social innovation – work during turbulent times is of increased significance. This paper carries out a systematically conducted literature review on the forms of social innovation arisen during the first year of the pandemic. Based upon our findings, areas for middle range theorizing on how social innovation works under conditions of turbulence and a prospective research agenda are explored
Hyaluronan delivery by polymer demixing in polysaccharide-based hydrogels and membranes for biomedical applications
Alginate-based membranes containing hyaluronic acid (HA) were manufactured by freeze-drying calcium-reticulated hydrogels. The study of the distribution of the two macromolecules within the hydrogel enabled to highlight a polymer demixing mechanism that tends to segregate HA in the external parts of the constructs. Resistance and pliability of the membranes were tuned, while release and degradation studies enabled to quantify the diffusion of both polysaccharides in physiological solution and to measure the viable lifetime of the membranes. Biological studies in vitro proved that the liquid extracts from the HA-containing membranes stimulate wound healing and that fibroblasts are able to colonize the membranes. Overall, such novel alginate-HA membranes represent a promising solution for several medical needs, in particular for wound treatment, giving the possibility to provide an in situ administration of HA from a resorbable device
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Institutionalizing Experimental Places for Inclusive Social Innovation: From Utopias to Heterotopias.
This essay embraces a notion of critical scholarship concerned with proposing normative and actionable alternatives that can create more inclusive societies and focuses on the role of institutionalizing experimental places for inclusive social innovation as a bottom-up strategic response to welfare state reforms. By mobilizing the notions of utopias and heterotopias in Foucault, the paper sheds light on the opportunity to move from policy utopias to democratic heterotopias, discussing the politics embedded in this cognitive shift and the democratic nature of social innovation changing social and governance relations by interacting with politico-administrative systems. Some obstacles to institutionalizing social innovation are highlighted, as well as some key governance mechanisms that can be activated either by public and/or social purpose organizations to try to overcome those obstacles. Finally, we discuss the importance of linking inclusive social innovation with democratic, rather than market logics
Negotiating autonomy in the public sector and nonprofits "collaborations" in politically contested fields
Nonprofits are increasingly involved in cross-sectoral collaborations with the public sector. However, we know little about the dynamics behind these collaborations and what happens to them in politically contested fields where actors may have divergent positions. In this article, a multi-country comparison of data gathered from semi-structured interviews (n = 68) with representatives of nonprofits involved in the labor market inclusion of newcomers is presented. Our findings indicate that, in politically contested fields, the possibility of participating in cross-sectoral collaborations (political autonomy) is influenced by nonprofits' financial and ideological autonomy. Welfare models and migration regimes play a fundamental role in shaping the inclusion of these organizations in collaborations, and in most cases, the collaborations are based on latent conflicts. Our article discusses that if the costs of autonomy associated with cross-sectoral collaborations are not offset, the collaboration in a politically contested field becomes a liability for nonprofits (and their beneficiaries)
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