University of Malta
  • Imsida, Malta
Recent publications
The 2018/844 Energy Performance of Buildings Directive (EU) has widened the scope of appropriate design of buildings from a pure energy performance and carbon emissions perspective to a wider scope that includes indoor comfort, and indoor air quality among others. To this effect, external parameters, especially solar energy, have a strong impact on the energy performance of buildings in Mediterranean regions, which requires careful consideration when it comes to benefiting from natural lighting while avoiding solar overheating. This paper addresses the considerations of natural lighting in the deep renovation of a housing block in the Mediterranean climate of the Republic of Malta, comparing some of the usual illuminance ranges to achieve optimal conditions based on international recommendations. DesignBuilder v7.0.0.102 has been the selected software to model the building that has been calibrated through experimental measurements. The model enabled the natural lighting conditions in the building evaluated and the effectiveness of suggested improvements to be determined. Results pointed out that the building under study satisfies the international standards about the prevention of visual discomfort only. Increasing the size of windows in identified zones, especially the first floor, was found to help improve other natural lighting characteristics. One of the proposed designs (Model 6) that replaces single-glazed with double-glazed windows that include an external spectrally-selective coating would significantly improve access to natural light bringing the building closer to the recommended levels of Annual Sunlight Exposure and reducing artificial lighting usage by up to five times. The relocation of room spaces could also reduce the use of artificial lighting.
Embedded sensors operating within a reinforced concrete structure enable the timely detection of structural degradation causes, such as chloride ions present in the pore solution. The best communication protocol to use for inter‐device communication within the concrete structure would ideally be wireless such as an ultrasonic system. Concrete is a composite material which imposes constraints on ultrasonic transmission, especially when operating at frequencies above 100kHz where incident radiation is scattered by the aggregate. Furthermore, for an effective coupling mechanism, a liquid with high acoustic impedance is required to reduce energy reflection at the interface. This paper outlines the design, construction, and characterisation of a range of Piezoelectric Micromachined Ultrasonic Transducers (PMUTs) which are specifically designed to operate in liquids, at frequencies near or below 100kHz. The PMUT devices described in this paper have diaphragm diameters ranging between 550μm and 2,000μms which sizes are needed for PMUTs to resonate at the required low frequency. This paper outlines the device geometry calculations and the design and fabrication of the prototype devices. The resonant frequencies were determined using a laser vibrometer.
This work records the presence of 13 species of tubuliferan thrips from the Maltese Islands. Eleven of these species, namely Bolothrips dentipes , B. insularis , Priesneriella mavromoustakisi , Gynaikothrips uzeli , Haplothrips acanthoscelis , H. aculeatus , H. setiger , H. tritici , Karnyothrips flavipes , Liothrips reuteri and Neoheegeria dalmatica are new records for the Maltese Islands. Two species: Gynaikothrips ficorum and Karnyothrips flavipes can be described as subcosmopolitan in distribution, another three species: Haplothrips aculeatus , H. setiger and H. tritici are distributed across the Holarctic and Palaearctic regions, while a further seven: Bolothrips dentipes , B. insularis , Haplothrips acanthoscelis , Liothrips oleae , L. reuteri , Neoheegeria dalmatica and Priesneriella mavromoustakisi have a European and/or Mediterranean distribution. Gynaikothrips ficorum and G. uzeli are considered as alien species. A key to the Tubulifera of the Maltese Islands as well as chorological data for these recorded species are provided in this work.
The Edinburgh Companion to the Essay distinguishes itself by the wide range and scope of its themes, voices and approaches. Thirty-five leading essayists, literary critics and writing instructors explore the essay from multiple perspectives, including its theories, forms and histories as well as its cultural, political and pedagogical contexts. In particular, the volume extends the theory of the essay by addressing topics such as the construction of an essayistic self and the political dimensions of essaying. It further explores the relationship between the essay and other forms, such as philosophical writing, the column, science writing, the novel, the lyric and the advert as well as the essay in digital spaces.
Long-term data analysis of the hourly ozone volume fractions in the middle of the Mediterranean Seawas carried out covering a period of 22 years. It was noticed that the amount of ozone during this period very rarely exceeded the recommended upper limit value of 80 ppb and that the amount of tropospheric ozone in the area is rather low. Fourier data analysis shows the presence of only a seasonal cycle in ozone concentrations. Statistical analysis of the data is showing a slightly negative trend in ozone concentrations of −0.46 ± 0.08 ppb/year for average values and a slightly higher negative trend of −0.54 ± 0.11 ppb/year for the 95th percentile values. These results obtained through simple linear regression were confirmed using the more appropriate Mann–Kendall test. The possible quadratic trend was not observed for the whole series of data. Air mass trajectories were calculated for those days in the year with the highest pollution, indicating that during those days horizontal air transfer, in most cases, brings the air mass from the North and from Sicily in Southern Italy.
Service innovation has come to represent an essential underpinning necessitated for enhanced value creation, competitiveness, idiosyncrasy, and long-term survival in contemporary contexts. Given the importance of this construct, a substantial corpus of the literature has developed and been devoted towards exploring this phenomenon. Despite increasing interest in this field, however, theoretical approaches solely dedicated towards service innovation have yet to materialize, while scholars remain divided on fundamental aspects of service innovation, e.g., the developmental paths through which innovation emerges. Compounding these issues, explorations aimed at investigating service innovation in the context of tourism enterprises remain nascent, while limited attention has been placed on investigating the role of ITs and ICTs in the innovation processes of tourism enterprises. To counteract these shortcomings and based on Buhagiar et al.’s [51] conceptual model of service innovation, this paper investigates the micro-foundation processes deployed in boutique hotels in Valletta, Malta, to reconfigure knowledge resources and establish innovation outcomes. Concurrently, this research explores the inflection points at which ITs and ICTs are deployed in the innovation processes of boutique hotels in Valletta, Malta, and examines how such technologies influence the innovation activities of these hotels.
Luthra, Peraza‐Santiago, Beeson, Saltzman, Crinnion, and Magnuson (2021) present data from the lexically mediated compensation for coarticulation paradigm that they claim provides conclusive evidence in favor of top‐down processing in speech perception. We argue here that this evidence does not support that conclusion. The findings are open to alternative explanations, and we give data in support of one of them (that there is an acoustic confound in the materials). Lexically mediated compensation for coarticulation thus remains elusive, while prior data from the paradigm instead challenge the idea that there is top‐down processing in online speech recognition.
During the signal detection process, statistical methods are used to identify drug–event combinations (DECs) which are disproportionately reported when compared with other drugs and events in the entire database. We hypothesise that the high volume of COVID-19 vaccine adverse drug reaction (ADR) reports transmitted to EudraVigilance may have affected the performance of disproportionality statistics used in routine signal detection, potentially resulting in signals either being masked, or false associations being flagged as potential signals. Our aim was to study the impact of COVID-19 vaccine spontaneous reporting on statistical signal detection in EudraVigilance. We recalculated the reporting odds ratio (ROR) for signals that were previously discussed at the level of the Pharmacovigilance Risk Assessment Committee, or signals that were retrieved from EudraVigilance, by omitting COVID-19 vaccine reports from the standard ROR calculation and then comparing the lower confidence interval (LCI) of the recalculated ROR to the LCI of the actual ROR in EudraVigilance. In total, 52 signals for 38 active substances were reviewed. For 35 signals, the LCI of the recalculated ROR value was lower than the LCI of the actual ROR (suggesting that COVID-19 vaccine ADR reporting had a positive effect on the strength of the signal) while for 15 signals the LCI of the recalculated ROR value was higher than the LCI of the actual ROR (suggesting that COVID-19 vaccine ADR reporting had an attenuating effect on the strength of the signal). For two signals, no change in the ROR was observed. In our analysis, six significant results were found. Five DECs were found to be masked: bleomycin and immune thrombocytopenia (actual ROR LCI = 0.94, recalculated ROR LCI = 1.02), vortioxetine and heavy menstrual bleeding (actual ROR LCI = 0.3, recalculated ROR LCI = 1.06), caplacizumab and heavy menstrual bleeding (actual ROR LCI = 0.98, recalculated ROR LCI = 3.47), ziprasidone and amenorrhoea (actual ROR LCI = 0.84, recalculated ROR LCI = 1.67), and azacitidine and pericarditis (actual ROR LCI = 0.81, recalculated ROR LCI = 2.01). For the DEC of adalimumab and immune reconstitution inflammatory syndrome, the LCI of the actual ROR value was 1.14 and removing COVID-19 vaccine reporting resulted in an LCI of the recalculated ROR value of 0.94 (below threshold). We demonstrated five cases of masking and one case of false-positive association due to the influence of COVID-19 vaccine spontaneous reporting on the ROR. This suggests that the high number of adverse drug reaction reports for COVID-19 vaccines in EudraVigilance has the potential to affect routine statistical signal detection activities. The impact of COVID-19 vaccine ADR reports on current signal detection practices requires further evaluation and solutions to tackle masking issues in EudraVigilance may need to be developed.
Due to the increase in bacterial resistance, improving the anti-infectious immunity of the host is rapidly becoming a new strategy for the prevention and treatment of bacterial pneumonia. However, the specific lung immune responses and key immune cell subsets involved in bacterial infection are obscure. Actinobacillus pleuropneumoniae (APP) can cause porcine pleuropneumonia, a highly contagious respiratory disease that has caused severe economic losses in the swine industry. Here, using high-dimensional mass cytometry, the major immune cell repertoire in the lungs of mice with APP infection was profiled. Various phenotypically distinct neutrophil subsets and Ly-6C ⁺ inflammatory monocytes/macrophages accumulated post-infection. Moreover, a linear differentiation trajectory from inactivated to activated to apoptotic neutrophils corresponded with the stages of uninfected, onset, and recovery of APP infection. CD14 ⁺ neutrophils, which mainly increased in number during the recovery stage of infection, were revealed to have a stronger ability to produce cytokines, especially IL-10 and IL-21, than their CD14 ⁻ counterparts. Importantly, MHC-II ⁺ neutrophils with antigen-presenting cell features were identified, and their numbers increased in the lung after APP infection. Similar results were further confirmed in the lungs of piglets infected with APP and Klebsiella pneumoniae infection by using a single-cell RNA-seq technique. Additionally, a correlation analysis between cluster composition and the infection process yielded a dynamic and temporally associated immune landscape where key immune clusters, including previously unrecognized ones, marked various stages of infection. Thus, these results reveal the characteristics of key neutrophil clusters and provide a detailed understanding of the immune response to bacterial pneumonia.
Purpose of Review Cardiovascular diseases are the leading cause of mortality globally. Identifying patients at risk is important to initiate preventive strategies. Over the last few decades, the role of the endothelium and its impact on arterial stiffness have been recognised as playing a pivotal role in cardiovascular disease. This review will focus on the effect of arterial stiffness in different patient cohorts with regard to cardiovascular morbidity and mortality, as well as its use in clinical practice. Recent Findings Arterial stiffness is associated with a range of cardiovascular risk factors and is an independent predictor of cardiovascular mortality. The gold standard for evaluating arterial stiffness is pulse wave velocity. Recently, cardio-ankle vascular index has been implemented as an easy and highly reproducible measure of arterial stiffness. Moreover, certain pharmacologic agents may modify arterial stiffness and alter progression of cardiovascular disease. Summary The endothelium plays an important role in cardiovascular disease. Implementing assessment of arterial stiffness in clinical practice will improve stratification of patients at risk of cardiovascular disease and help modify disease progression.
Osteoporosis is a metabolic bone disorder which increases fragility fracture risk. Elderly individuals, especially postmenopausal women, are particularly susceptible to osteoporosis. Although rare, osteoporosis in children and young adults is becoming increasingly evident, highlighting the need for timely diagnosis, management and follow-up. Early-onset osteoporosis is defined as the presence of a low BMD (Z-score of ≤ -2.0 in individuals aged < 20 years; T-score of ≤ -2.5 in those aged between 20 to 50 years) accompanied by a clinically significant fracture history, or the presence of low-energy vertebral compression fractures even in the absence of osteoporosis. Affected children and young adults should undergo a thorough diagnostic workup, including collection of clinical history, radiography, biochemical investigation and possibly bone biopsy. Once secondary factors and comorbidities are excluded, genetic testing should be considered to determine the possibility of an underlying monogenic cause. Defects in genes related to type I collagen biosynthesis are the commonest contributors of primary osteoporosis, followed by loss-of-function variants in genes encoding key regulatory proteins of canonical WNT signalling (specifically LRP5 and WNT1), the actin-binding plastin-3 protein (encoded by PLS3) resulting in X-linked osteoporosis, and the more recent sphingomyelin synthase 2 (encoded by SGMS2) which is critical for signal transduction affecting sphingomyelin metabolism. Despite these discoveries, genetic causes and underlying mechanisms in early-onset osteoporosis remain largely unknown, and if no causal gene is identified, early-onset osteoporosis is deemed idiopathic. This calls for further research to unravel the molecular mechanisms driving early-onset osteoporosis that consequently will aid in patient management and individualised targeted therapy.
The 2020s certainly represent a significant change in the approach to the teaching system and research in university education. Although ML and digitization in higher education have been addressed since the 2000s, their application became mandatory during the recent epidemic. As a result of the transition, the years 2020-2021 were marked by a strong shift to work in the online environment, based on digital networks for communication, payments and learning. This has definitely determined the whole society to adapt to the digital age. Therefore, the corroboration between ML and digitization has become vital. This article is called to present how Artificial Intelligence can improve the efficiency of university teaching and research, by embracing modern communication technologies and meeting the demands of students in a virtual setting.
Aim The Genetic Absence Epilepsy Rats from Strasbourg (GAERS) are an inbred polygenic model of childhood absence epilepsy (CAE), which, as their non‐epileptic control (NEC) rats, are derived from Wistar rats. While the validity of GAERS in reproducing absence seizures is well established, its use as a model for CAE psychiatric comorbidities has been subject to conflicting findings. Differences in colonies, experimental procedures, and the use of diverse controls from different breeders may account for these disparities. Therefore, in this study, we compared GAERS, NEC, and Wistar bred in the same animal facility with commercially available Wistar (Cm Wistar) as a third control. Methods We performed hole board (HB) and elevated plus maze (EPM) tests that were analyzed with standard quantitative and T‐pattern analysis in male, age‐matched Cm Wistar and GAERS, NEC, and Wistar, bred under the same conditions, to rule out the influence of different housing factors and provide extra information on the structure of anxiety‐like behavior of GAERS rats. Results Quantitative analysis showed that GAERS and NEC had similar low anxiety‐like behavior when compared to Cm Wistar but not to Wistar rats, although a higher hole‐focused exploration was revealed in NEC. T‐pattern analysis showed that GAERS, NEC, and Wistar had a similar anxiety status, whereas GAERS and NEC exhibited major differences with Cm Wistar but not Wistar rats. EPM results indicated that GAERS and NEC also have similar low anxiety compared to Cm Wistar and/or Wistar rats. Nevertheless, the analysis of the T‐pattern containing open‐arm entry showed GAERS and Wistar to be less anxious than NEC and Cm Wistar rats. Conclusion To summarize, comorbid anxiety may not be present in male GAERS rats. This study also highlighted the importance of including a control Wistar group bred under the same conditions when evaluating their behavior, as using Wistar rats from commercial breeders can lead to misleading results.
The application of more electrified systems in aircraft is required to achieve the target of a more sustainable aviation industry. This in turn relies on the development of new electro-mechanical devices to ensure reliability of critical aircraft functions during flight. The aim of this work is to develop and test a device capable of protecting permanent magnet generators from damage, thus enabling the practical use of such high power density generators in aircraft while eliminating their inherent vulnerability to sustained electrical faults. A novel electromechanical actuator concept for decoupling a permanent magnetic generator from an aircraft gas turbine engine is introduced and experimentally validated. The proposed concept combines a coaxial magnetic coupling with an electromagnetic actuator, allowing for rapid disconnection in case of electrical fault detection. The 2D finite element magnetic analysis methodology employed in the design of the magnetic coupling and electromagnetic actuator is validated with experiments that reveal the peak torque results of the magnetic coupling are accurate to within a 2.5% error and the actuator can produce the 450 N pull force required for disconnection. The device is capable of operating at a maximum speed of 12,000 RPM and transmitting a load of 32 Nm.
For aerospace electrical machines (EMs), the partial discharge (PD) risk is becoming much more severe due to higher DC link voltage levels and faster switching devices. Traditionally, EMs for safety-critical applications mainly rely on over-engineering methods to guarantee reliability. However, a recent shift towards reliability-oriented design, which is based on understanding the physics of failure, allows for meeting the reliability requirements while ensuring performance. From the perspective of the reliability-oriented methodology, the PD-free design of a starter/generator (S/G) with a 540V DC bus is presented and the main steps for a comprehensive PD risk evaluation are discussed. First, the PD inception mechanism is experimentally investigated under pulse voltage excitation for several rise times, temperatures, and pressure values. Then the measured partial discharge inception voltage (PDIV) values are used to perform an accurate PD risk assessment, which includes the winding hotspot temperature resulting from the S/G mission profile, the environment operating conditions, and the connection cable length. Finally, the PD risk of a S/G with a higher DC bus (i.e., 800V) is examined to comply with the future aircraft voltage level.
This paper presents the design process for an electromagnetically actuated coupling disconnection system relying on contactless torque transfer. The device can replace existing mechanical and electromagnetic clutches to provide enhanced protection against over torque conditions resulting from faults in the coupled machines. The novel disconnection system contains a coaxial magnetic coupling (CMC) that can be fully disengaged via an electromagnetic actuator. This system configuration improves the fault performance of magnetic couplings and reduces the losses and maintenance requirements associated with other clutch designs. The end result is a more reliable and versatile coupling solution that can be used in a broad range of machine applications. The design and optimization process builds upon existing knowledge of CMC design to produce a practical device that can transmit a maximum torque of 100 Nm and rotate at a maximum speed of 20,000 RPM. The electromagnetic actuator is tested to ensure the system is capable of disengaging the coupling. An investigation is made into the axial forces present in a CMC when the magnets are separated. It is concluded that decoupling a CMC is practical and achievable with the presented electromagnetic actuator design.
Institution pages aggregate content on ResearchGate related to an institution. The members listed on this page have self-identified as being affiliated with this institution. Publications listed on this page were identified by our algorithms as relating to this institution. This page was not created or approved by the institution. If you represent an institution and have questions about these pages or wish to report inaccurate content, you can contact us here.
13,511 members
Alex Gatt
  • Department of Pathology
Noel Aquilina
  • Department of Chemistry
Gianluca Valentino
  • Department of Communications and Computer Engineering
Janet Mifsud
  • Department of Clinical Pharmacology and Therapeutics
Arthur Rodriguez Gonzalez Cortes
  • Department of Dental Surgery
MSD 2080, Imsida, Malta
Head of institution
Professor Alfred Vella
+356 23402340