Arbitrary aperture synthesis with nonlocal leaky-wave metasurface antennas.

The emergence of new technological needs in 5 G/6 G networking and broadband satellite internet access amplifies the demand for innovative wireless communication hardware, including high-performance low-profile transceivers. In this context, antennas based on metasurfaces - artificial surfaces engineered to manipulate electromagnetic waves at will - represent highly promising solutions. In this article, we introduce leaky-wave metasurface antennas operating at micro/millimeter-wave frequencies that are designed using the principles of quasi-bound states in the continuum, exploiting judiciously tailored spatial symmetries that enable fully customized radiation. Specifically, we unveil additional degrees of control over leaky-wave radiation by demonstrating pointwise control of the amplitude, phase and polarization state of the metasurface aperture fields by carefully breaking relevant symmetries with tailored perturbations. We design and experimentally demonstrate metasurface antenna prototypes showcasing a variety of functionalities advancing capabilities in wireless communications, including single-input multi-output and multi-input multi-output near-field focusing, as well as far-field beam shaping.

Switchable edge-line coupler based on parity time-reversal duality symmetry.

A compact broadband Edge-Line Coupler (ELC) based on Parity Time-reversal Duality (PTD) symmetry has been conceived, designed, constructed and measured. The coupler connects four PTD bifilar edge lines (BELs), recently introduced by the authors. The PTD-BELs are constituted by a parallel plate waveguide whose walls are formed by a junction between Perfect Electric Conductor (PEC) and Perfect Magnetic Conductor (PMC) boundary conditions. Reversing the axis orthogonal to the plates interchanges the position of PEC and PMC. Such a waveguide supports unimodal transverse electromagnetic (TEM) propagation, extremely confined along the top and bottom junction edges; its propagation is protected against backscattering from any discontinuity that preserves the PTD symmetry. The ELC presented here is constituted by a 4-port junction in which each port is intrinsically matched due to the PTD symmetry, strongly coupled with a second port, strongly decoupled with a third port, and weakly coupled with a fourth port. The ELC is designed by using a mushroom metasurface for the PMC portion of the device; the connection is based on a switch circuit which imposes open and short conditions on the two opposite sides of the structure. Switching simultaneously the open and short circuits reroutes the signal in a different port, while maintaining the same level of coupling with the other ports. A static prototype has been built and its measurements have confirmed the matching performance and the good directionality of the coupler in a broadband frequency range between 24 and 30 GHz.

Evaluation of Control Program Against Streptococcus agalactiae Infection in Dairy Herds During 2019-2021 in Emilia-Romagna Region, Northern Italy.

Streptococcus agalactiae (group B Streptococcus, GBS) is a causative agent of mastitis in dairy cattle, mainly causing a subclinical disease associated with a high somatic cell count (SCC), and a consequent decrease in production yield and quality of milk. GBS has been almost eradicated in many Northern European countries, but there are warnings of its re-emergence as a zoonotic threat. In Italy, only two regions carry out a GBS control program: Lombardy and Emilia-Romagna. In Emilia-Romagna, the program has been in place since 2019 and provides for the bacteriological culture of bulk-tank milk (BTM) of all dairy farms every 6 months and the voluntary application of herd eradication programs in the case of positive results. To assess the progress of the program in Emilia Romagna, in terms of herd-level prevalence and GBS transmission between herds, we analyzed the results of 17,056 BTM cultures from 2,831 dairy herds, sampled bi-annually in the period 2019-2021 (six rounds total). The impact of GBS infection on SCC and milk production was also evaluated. The results show a decreasing trend in both the incidence rate (from 3.0 to 1.5%) and apparent prevalence (from 8.9 to 5.2%) of GBS over the study period. By using a susceptible-infected-susceptible (SIS) model for the estimation of the transmission parameters, a basic reproductive number R0 of 1.4 was calculated, indicating an active spread of GBS in the dairy cattle population of the Emilia-Romagna region. GBS infected farms have a consistently higher BTM SCC than negative ones (+77,000 cells/ml), corresponding to a 0.4 kg/cow/day milk loss. Moreover, GBS infected herds resulted in almost three times more likelihood of having non-marketable milk by exceeding the legal SCC limit. This study demonstrates the need to maintain the current control program against GBS to lower its occurrence and prevent significant market losses to farmers.

Power balance and efficiency of metasurface antennas.

This paper presents two methods for the efficient evaluation of the power balance in circular metasurface (MTS) antennas implementing arbitrary modulated surface impedances on a grounded dielectric slab. Both methods assume the surface current in the homogenized MTS to be known. The first technique relies on the surface current expansion with Fourier-Bessel basis functions (FBBF) and proceeds by integration of the Poynting vector on a closed surface. The second method is based on the evaluation of the residue of the electric field spectrum at the surface-wave (SW) pole, and is demonstrated by using a current expansion in Gaussian ring basis functions (GRBF). The surface current expansions can be directly obtained either by analyzing the antenna with a Method of Moments (MoM) tool for homogenized MTSs based on FBBF or GRBF, or derived by a projection process. From there, the power contributions, namely the total power delivered by the feed, the radiated power, the SW power, and the Ohmic power losses in the dielectric are computed. Several efficiency metrics are presented and discussed: tapering efficiency, conversion efficiency, loss factor, and diffraction factor. Since the MTS apertures at hand are leaky-wave (LW) antennas, the designer must find a compromise between the aperture efficiency and the conversion efficiency. This requires accurate and fast computational techniques for the efficiency. The present paper demonstrates for the first time that the efficiency of MTS antenna devices can be accurately evaluated in a few minutes. The compromise that should be made during the design process between the tapering efficiency and the conversion efficiency is highlighted. The impact on the efficiency of isotropic versus anisotropic MTS, uniform versus non-uniform modulation index, is analyzed. An excellent agreement is obtained between both approaches, commercial software, and experimental data.

A proposal for a comprehensive approach to infections across the surgical pathway.

Despite evidence supporting the effectiveness of best practices in infection prevention and management, many healthcare workers fail to implement them and evidence-based practices tend to be underused in routine practice. Prevention and management of infections across the surgical pathway should always focus on collaboration among all healthcare workers sharing knowledge of best practices. To clarify key issues in the prevention and management of infections across the surgical pathway, a multidisciplinary task force of experts convened in Ancona, Italy, on May 31, 2019, for a national meeting. This document represents the executive summary of the final statements approved by the expert panel.

Detection of Hepatitis E Virus in Livers and Muscle Tissues of Wild Boars in Italy.

In industrialized countries, hepatitis E is now recognized as an emerging zoonosis. Autochthonous cases have been increased over recent years in Europe and are mainly associated with HEV-3 infections. Pigs and wild boars are considered the main reservoirs of the zoonotic HEV-3 and HEV-4 genotypes. Over the past decade, the number of wild boars has drastically increased in Europe. Due to habitats closer to humans and domestic animals, the role of wild boar as a reservoir of the zoonotic HEV is considered to be an emerging issue. In this study, we investigated the presence of HEV RNA by a real-time RT-PCR assay in paired liver and muscle samples collected from 196 wild boars (Sus scrofa) hunted in the two areas of Central and Southern Italy. Twenty animals (10.2%) were HEV RNA positive in livers, 11 of which were also positive in muscles. The ORF2 and ORF1 partial viral sequences were obtained for nine paired livers and muscles, and when aligned were identical to each other. Phylogenetic analyses confirmed detection of different HEV-3 subtypes: 3c, 3f, 3i and some that were not assigned to any subtypes that have so far been identified. Results need further investigation because they are based on analyses of sequences of short genome regions. Nevertheless, we observed that the same strains were circulating in the wild boar populations from the two investigated areas, confirming persistence of the same HEV strains in the wild boar population over time.

Metasurface Antennas: New Models, Applications and Realizations.

This paper presents new designs, implementation and experiments of metasurface (MTS) antennas constituted by subwavelength elements printed on a grounded dielectric slab. These antennas exploit the interaction between a cylindrical surface wave (SW) wavefront and an anisotropic impedance boundary condition (BC) to produce an almost arbitrary aperture field. They are extremely thin and excited by a simple in-plane monopole. By tailoring the BC through the shaping of the printed elements, these antennas can be largely customized in terms of beam shape, bandwidth and polarization. In this paper, we describe new designs and their implementation and measurements. It is experimentally shown for the first time that these antennas can have aperture efficiency up to 70%, a bandwidth up to 30%, they can produce two different direction beams of high-gain and similar beams at two different frequencies, showing performances never reached before.

Quantification and genetic diversity of Hepatitis E virus in wild boar (Sus scrofa) hunted for domestic consumption in Central Italy.

Hepatitis E is an emerging disease in industrialized countries. The food-borne transmission of hepatitis E virus (HEV) is associated principally with products derived from the domestic pig, the wild boar, and deer; however, few quantitative data are available on HEV loads in animals used in food production. This study assessed HEV occurrence, viral load and genetic variability in wild boar hunted for domestic consumption in the district of Viterbo (Central Italy) where high anti-HEV IgG seroprevalence values are reported in humans. A total of 332 liver and 69 intestine samples were obtained from wild boar hunted between 2011 and 2014. The liver tissue in 54 of the animals (16.3%) was HEV-positive. Viral loads in quantifiable liver samples (n = 29) ranged between 3.2 × 102 and 3.8 × 105 genome copies (g.c.)/g with a mean value of 1.85 × 104 g.c./g. A statistically significant positive correlation was found between viral concentration in liver and intestinal tissue, though mean viral load in the intestines was lower (3.13 × 103 g.c./g). Twenty-six samples were characterized molecularly as genotype 3 (G3) and four subtypes (a, c, f and l) were detected. Finally, twelve samples with near identical sequences were identified as G3 but could not be assigned to any of the known subtypes, and could therefore represent a potentially new subtype.

Behaviour and eating habits as determinants for human opisthorchiasis in the Bolsena Lake area, Italy.

In Italy, food-borne outbreaks of opisthorchiasis have occurred since 2003, all of them originating from some lakes in Central Italy where the only European liver fluke, Opisthorchis felineus (Rivolta, 1884) is endemic. The aim of the present study is to investigate the factors that may facilitate the life cycle of O. felineus in the area of Bolsena Lake, the knowledge of the local population about opisthorchiasis, and preventative healthcare measures. We performed a descriptive observational study through the submission of questionnaires to three target populations: fishermen who fish exclusively in Bolsena Lake, restaurateurs whose businesses are close to the lake and general population living in the province of Viterbo. Results showed hazardous behaviours and eating habits in the three target populations, as well as a poor knowledge of opisthorchiasis and preventative healthcare measures.

Control and prevention measures for legionellosis in hospitals: A cross-sectional survey in Italy.

Risk assessment, environmental monitoring, and the disinfection of water systems are the key elements in preventing legionellosis risk. The Italian Study Group of Hospital Hygiene of the Italian Society of Hygiene, Preventive Medicine, and Public Health and the Italian Multidisciplinary Society for the Prevention of Health Care-Associated Infections carried out a national cross-sectional survey to investigate the measures taken to prevent and control legionellosis in Italian hospitals. A multiple-choice questionnaire was developed, comprising 71 questions regarding hospital location, general characteristics, clinical and environmental surveillance, and control and preventive measures for legionellosis in 2015. Overall, 739 hospitals were enrolled from February to June 2017, and 178 anonymous questionnaires were correctly completed and evaluated (response rate: 24.1%). The survey was conducted using the SurveyMonkey® platform, and the data were analyzed using Stata 12 software. Of the participating hospitals, 63.2% reported at least one case of legionellosis, of which 28.2% were of proven nosocomial origin. The highest case numbers were reported in the Northern Italy, in hospitals with a pavilion structure or cooling towers, and in hospitals with higher numbers of beds, wards and operating theaters. Laboratory diagnosis was performed using urinary antigen testing alone (31.9%), both urinary antigen testing and single antibody titer (17.8%), or with seroconversion also added (21.5%). Culture-based or molecular investigations were performed in 28.8% and 22.1% of the clinical specimens, respectively. The water systems were routinely tested for Legionella in 97.4% of the hospitals, 62% of which detected a positive result (> 1000 cfu/L). Legionella pneumophila serogroup 2-15 was the most frequently isolated species (58.4%). The most common control measures were the disinfection of the water system (73.7%), mostly through thermal shock (37.4%) and chlorine dioxide (34.4%), and the replacement (69.7%) or cleaning (70.4%) of faucets and showerheads. A dedicated multidisciplinary team was present in 52.8% of the hospitals, and 73% of the hospitals performed risk assessment. Targeted training courses were organized in 36.5% of the hospitals, involving nurses (30.7%), physicians (28.8%), biologists (21.5%), technicians (26.4%), and cleaners (11%). Control and prevention measures for legionellosis are present in Italian hospitals, but some critical aspects should be improved. More appropriate risk assessment is necessary, especially in large facilities with a high number of hospitalizations. Moreover, more sensitive diagnostic tests should be used, and dedicated training courses should be implemented.

Catheter-associated urinary tract infection: Role of the setting of catheter insertion.

BACKGROUND: This study aimed to describe the epidemiology of catheter-associated urinary tract infections (CAUTIs) in patients admitted to a surgical ward in Central Italy and to analyze the associated risk factors. METHODS: An active surveillance program for CAUTI was carried out in patients catheterized for at least 48 hours. Place of catheter insertion (operating room, hospital ward, cystoscopy room, emergency care unit), indication for catheterization and its duration, among other risk factors were monitored until discharge. Antibiotic resistance profiles of isolates were analyzed. RESULTS: There were 641 catheterized patients monitored for CAUTI onset. Of these, 40 (6.2%) developed a CAUTI (rates were 15.1/1,000 catheter days, 95% confidence interval [CI], 11.9-22.6; 8.7/1,000 patient days, 95% CI, 6.9-13.1). Patients with CAUTI were older (P < .05) and their durations of hospitalization and catheterization were both longer compared with those who were not affected (P < .05). Catheterization >4 days (odds ratio [OR] = 8.21; 95% CI, 3.79-17.73; P < .05) and place of catheter insertion different from the operating room (OR = 7.9; 95% CI, 2.83-22.08; P < .05, for catheters placed in the ward) were associated with CAUTI. Among the micro-organisms isolated in CAUTIs, the most common were Pseudomonas aeruginosa (41.5%), Klebsiella pneumoniae (19.5%), and Escherichia coli (12.2%); 82.5% of them were resistant to different classes of antibiotics. CONCLUSION: These results highlight the role played by the setting of catheter insertion in CAUTIs onset, therefore reflecting the importance of hand hygiene and proper aseptic insertion techniques as crucial determinants in CAUTIs prevention.

Measles among healthcare workers in a teaching hospital in central Italy.

OBJECTIVES: The aim of this report is to describe a measles cluster involving health-care workers (HWCs) that occurred in a teaching hospital in central Italy during winter 2011 and the efforts made to promptly identify all the susceptible contacts in order to stop, as soon as possible, transmission of the infection within the hospital. METHODS: An epidemiological investigation took place. The immunization status of all the exposed individuals was assessed by personal interviews (history of measles or measles vaccine). Serologie screening for personnel not immune to measles was performed. RESULTS: Four cases of measles infection in HCWs were identified; of the 72 HCWs tested for measles immunity, 50 reported a past history of measles, while 22 underwent serological screening, which showed that all were IgG positive except for one case, which was excluded from duty as recommended. Strict adherence to use of alcohol-based hand rub and rapid implementation of appropriate isolation precautions are essential but insufficient to prevent measles outbreaks in hospital settings. Vaccination is the only reliable protection against nosocomial spread of measles. Therefore, assessing the immunization status of HCW and implementing vaccination strategies are needed in order to virtually set to zero the risk of acquiring and spreading measles in healthcare settings.