Analiza svojstava izmjenjivačkih mrežnih priključaka fotonaponskih sustava

The present trend towards extended adoption of energy production from renewable sources is leading to increased attention towards the diffusion of grid-connected photovoltaic (PV) systems. Different technologies are available for the connection of the PV systems to the grid through inverter-based Power Conditioning Units (PCUs). This paper presents the results of a comparative study referred to the characteristics of different types of PCUs, based on the experimental results obtained for a wide range of solar irradiance and operating conditions. The performance of the grid connection has been characterised by using a set of parameters, referred both to the DC and to the AC side of the inverter, such as the efficiency of the maximum power point tracking, the DC/AC efficiency, the power factor and the harmonic distortion of voltage and current at the interface with the grid. The PV systems have been further characterised by considering their ability of avoiding the undesired islanding operation through relatively fast detection of the islanding conditions and fast PV system shutdown. The results are discussed and compared to the specifications provided by the manufacturers and to the limits imposed by some standards.Sadašnji trend koji vodi prema sve većoj potrebi za proizvodnjom energije iz obnovljivih izvora energije usmjerava povećanu pozornost prema primjeni fotonaponskih (PV) sustava spojenih u mrežu. Različite su tehnologije raspoložive za spajanje PV sustava na mrežu preko izmjenjivačkih energetskih jedinica (PCU). Ovaj rad prikazuje rezultate usporednog proučavanja karakteristika različitih tipova izmjenjivačkih energetskih jedinica (PCU) na osnovi eksperimentalnih rezultata dobivenih za široki opseg Sunčeva zračenja i uvjeta rada. Svojstva mrežnog spoja okarakterizirana su korištenjem skupa parametara koji se odnose i na istosmjernu (DC) i na izmjeničnu (AC) stranu izmjenjivača, kao što su efikasnost praćenja točke maksimalne snage, DC/AC efikasnosti, faktor snage i harmoničko izobličenje napona i struja na spoju s mrežom. Fotonaponski sustavi su dalje okarakterizirani uzimajući u obzir njihove sposobnosti izbjegavanja neželjene operacije otočnoga rada njegovom relativno brzom detekcijom i isključivanjem. Provedena je rasprava o rezultatima, a zatim su rezultati uspoređeni sa specifikacijama dobivenim od proizvođača i s ograničenjima proisteklima iz nekih standarda

Analiza svojstava izmjenjivačkih mrežnih priključaka fotonaponskih sustava

The present trend towards extended adoption of energy production from renewable sources is leading to increased attention towards the diffusion of grid-connected photovoltaic (PV) systems. Different technologies are available for the connection of the PV systems to the grid through inverter-based Power Conditioning Units (PCUs). This paper presents the results of a comparative study referred to the characteristics of different types of PCUs, based on the experimental results obtained for a wide range of solar irradiance and operating conditions. The performance of the grid connection has been characterised by using a set of parameters, referred both to the DC and to the AC side of the inverter, such as the efficiency of the maximum power point tracking, the DC/AC efficiency, the power factor and the harmonic distortion of voltage and current at the interface with the grid. The PV systems have been further characterised by considering their ability of avoiding the undesired islanding operation through relatively fast detection of the islanding conditions and fast PV system shutdown. The results are discussed and compared to the specifications provided by the manufacturers and to the limits imposed by some standards.Sadašnji trend koji vodi prema sve većoj potrebi za proizvodnjom energije iz obnovljivih izvora energije usmjerava povećanu pozornost prema primjeni fotonaponskih (PV) sustava spojenih u mrežu. Različite su tehnologije raspoložive za spajanje PV sustava na mrežu preko izmjenjivačkih energetskih jedinica (PCU). Ovaj rad prikazuje rezultate usporednog proučavanja karakteristika različitih tipova izmjenjivačkih energetskih jedinica (PCU) na osnovi eksperimentalnih rezultata dobivenih za široki opseg Sunčeva zračenja i uvjeta rada. Svojstva mrežnog spoja okarakterizirana su korištenjem skupa parametara koji se odnose i na istosmjernu (DC) i na izmjeničnu (AC) stranu izmjenjivača, kao što su efikasnost praćenja točke maksimalne snage, DC/AC efikasnosti, faktor snage i harmoničko izobličenje napona i struja na spoju s mrežom. Fotonaponski sustavi su dalje okarakterizirani uzimajući u obzir njihove sposobnosti izbjegavanja neželjene operacije otočnoga rada njegovom relativno brzom detekcijom i isključivanjem. Provedena je rasprava o rezultatima, a zatim su rezultati uspoređeni sa specifikacijama dobivenim od proizvođača i s ograničenjima proisteklima iz nekih standarda

Screening for Tuberculosis in Health Care Workers. Experience in an Italian Teaching Hospital

Health care workers (HCW) are particularly at risk of acquiring tuberculosis (TB), even in countries with low TB incidence. Therefore, TB screening in HCW is a useful prevention strategy in countries with both low and high TB incidence. Tuberculin skin test (TST) is widely used although it suffers of low specificity; on the contrary, the in vitro enzyme immunoassay tests (IGRA) show superior specificity and sensitivity but are more expensive. The present study reports the results of a three-year TB surveillance among HCW in a large teaching hospital in Rome, using TST (by standard Mantoux technique) and IGRA (by QuantiFERON-TB) as first- and second-level screening tests, respectively. Out of 2290 HCW enrolled, 141 (6.1%) had a positive TST; among them, 99 (70.2%) underwent the IGRA and 16 tested positive (16.1%). The frequency of HCW tested positive for TB seems not far from other experiences in low incidence countries. Our results confirm the higher specificity of IGRA, but, due to its higher cost, TST can be considered a good first level screening test, whose positive results should be further confirmed by IGRA before the patients undergo X-ray diagnosis and/or chemotherapy

Healthcare Associated Infections. educational intervention by "Adult Learning" in an Italian teaching hospital

An educational intervention for HAI prevention based on a combination of training, motivation and subsequent application in the current clinical practice in an Italian teaching hospital

Rupture of an isolated true superficial femoral artery aneurysm: case report

True isolated atherosclerotic aneurysm of the superficial femoral artery is a rare patology. We report a case of ruptured superficial femoral artery aneurysms (SFAA) not associated with aortic, common femoral or popliteal artery aneurysms. An emergency surgical procedure was performed and, after endoaneurysmal branches ligation, a ePTFE graft interposition was performed. The litterature review shows a prevalence of rupture as compared with ischemic complications and the need for surgical repair in case of SFAA with diameter twice the normal vessel size. Early diagnosis and management are recommended because of the lower morbility and mortality rates associated with elective surgery by comparison with emergency procedures

Le attività motorie e sportive come crescita socio-culturale del soggetto adolescente

La seguente ricerca delinea il paradigma scientifico che sottende la valenza formativa delle attività motorie e sportive come crescita socio-culturale dell’adolescente. Consapevoli, ormai, che le condotte educative vanno orientate nel rispetto di una sinergia genuina tra natura e cultura, possiamo asserire che non esistono capacità in astratto che attendano solo di essere illuminate da non si sa quali sollecitazioni culturali, semmai esiste un codice genetico che è tipico dell’uomo e che, nel rapporto dialettico tra filogenesi ed ontogenesi, “individua” e “differenzia” un essere umano dall’altro. Il mondo delle attività motorie e dello sport che, sin dalle sue origini, ha assunto una funzione importante nei processi di integrazione sociale è tra gli strumenti con i quali è possibile interagire a supporto di una formazione autentica e personalizzata del soggetto. Le attività motorie e sportive, infatti - ora consentendo una relazione armonica tra sviluppo del corpo e prestanza fisica, qualità morali e spirituali, ora in antitesi con l’ascetismo rinnegante i diritti del corpo - hanno contribuito a delineare i contorni di percorsi formativi finalizzati all’inclusione sociale e alla valorizzazione delle dimensioni dell’uomo

Characterization of the response of spring-based relative gravimeters during paroxysmal eruptions at Etna volcano

Gravity time sequences collected at Etna volcano by continuously recording spring-based relative gravimeters showed significant variations in temporal correspondence with paroxysmal eruptions. Since the observed gravity variations can only be partially related to subsurface mass redistribution phenomena, we investigated the instrumental effects due to ground vibrations such as those that accompany explosive activity. We simulated the performances of relative gravimeters with laboratory experiments to estimate their response to vertical and horizontal excitations. Laboratory tests were carried out using a vibrating platform capable of accelerating the instruments with intensities and frequencies, in both the vertical and horizontal directions, observed in the ground vibrations associated with paroxysmal events. The seismic signals recorded at Etna volcano during the 10 April 2011 lava fountain were analyzed to retrieve the parameters used to drive the vibration platform. We tested two gravimeters used for Etna volcano monitoring: the LaCoste & Romberg D#185 (Lafayette, CO, USA) and the Scintrex CG-3 M#9310234 (Concord, ON, Canada). The experiment results highlight that the vibrations resembling the seismic waves propagated during paroxysmal events cause an amplitude response in the gravity readings on the order of several hundred microgals (μGal). Generally, the relationship between the vibrations and the gravimeter response is nonlinear, with a fairly complex dependence on the frequencies and amplitudes of the signals acting on the gravimeters

Edible Insects an Alternative Nutritional Source of Bioactive Compounds: A Review

Edible insects have the potential to become one of the major future foods. In fact, they can be considered cheap, highly nutritious, and healthy food sources. International agencies, such as the Food and Agriculture Organization (FAO), have focused their attention on the consumption of edible insects, in particular, regarding their nutritional value and possible biological, toxicological, and allergenic risks, wishing the development of analytical methods to verify the authenticity, quality, and safety of insect-based products. Edible insects are rich in proteins, fats, fiber, vitamins, and minerals but also seem to contain large amounts of polyphenols able to have a key role in specific bioactivities. Therefore, this review is an overview of the potential of edible insects as a source of bioactive compounds, such as polyphenols, that can be a function of diet but also related to insect chemical defense. Currently, insect phenolic compounds have mostly been assayed for their antioxidant bioactivity; however, they also exert other activities, such as anti-inflammatory and anticancer activity, antityrosinase, antigenotoxic, and pancreatic lipase inhibitory activitie

Diagnostic and therapeutic aspects of hemiplegic migraine

Hemiplegic migraine (HM) is a clinically and genetically heterogeneous condition with attacks of headache and motor weakness which may be associated with impaired consciousness, cerebellar ataxia and intellectual disability. Motor symptoms usually last <72 hours and are associated with visual or sensory manifestations, speech impairment or brainstem aura. HM can occur as a sporadic HM or familiar HM with an autosomal dominant mode of inheritance. Mutations in CACNA1A, ATP1A2 and SCN1A encoding proteins involved in ion transport are implicated. The pathophysiology of HM is close to the process of typical migraine with aura, but appearing with a lower threshold and more severity. We reviewed epidemiology, clinical presentation, diagnostic assessment, differential diagnosis and treatment of HM to offer the best evidence of this rare condition. The differential diagnosis of HM is broad, including other types of migraine and any condition that can cause transitory neurological signs and symptoms. Neuroimaging, cerebrospinal fluid analysis and electroencephalography are useful, but the diagnosis is clinical with a genetic confirmation. The management relies on the control of triggering factors and even hospitalisation in case of long-lasting auras. As HM is a rare condition, there are no randomised controlled trials, but the evidence for the treatment comes from small studies

Interleukin-6 and Outcome of Chronic Hemodialysis Patients with SARS-CoV-2 Pneumonia

Background and Objectives: Chronic hemodialysis (CHD) patients are at increased risk of SARS-CoV-2 infection and the related complications and mortality of COVID-19 due to the high rate of comorbidities combined with advanced age. This observational study investigated the clinical manifestations of SARS-CoV-2 infection in CHD and the risk factors for patients ' death. Materials and Methods: The study included 26 CHD patients with SARS-CoV-2 pneumonia detected by positive RT-PCR on nasopharyngeal swabs and high-resolution computed tomography at hospital admission, aged 71 + 5.9 years, 14 of which (53.8%) were male, 20 (77%) under hemodiafiltration, and 6 (23%) on standard hemodialysis, with a median follow-up of 30 days. Results: Simple logistic regression analysis revealed that the factors associated with a higher risk of death were older age (OR: 1.133; 95%CI: 1.028-1.326, p = 0.0057), IL-6 levels at admission (OR: 1.014; 95%CI: 1.004-1.028, p = 0.0053), and C-reactive protein (OR: 1.424; 95%CI: 1.158-2.044, p < 0.0001). In the multiple logistic regression model, circulating IL-6 values at admission remained the only significant prognosticator of death. The ROC curve indicated the discriminatory cut-off value of 38.20 pg/mL of blood IL-6 for predicting death in chronic hemodialysis patients with SARS-CoV-2 pneumonia (sensitivity: 100%; specificity: 78%; AUC: 0.8750; p = 0.0027). Conclusions: This study identified a threshold of IL-6 levels at hospital admission for death risk in CHD patients with SARS-CoV-2 pneumonia. This might represent a valuable outcome predictor, feasibly better than other clinical, radiological, or laboratory parameters and preceding the IL-6 peak, which is unpredictable