Sidelobe level correction for parabolic antennas radiation pattern measurements in quasi-far-field conditions

A method and formulae for correction of the sidelobe level of the radiation pattern of a high gain antenna when measured in the Fresnel region are presented. After a thorough analysis of a large number of different cases, trend curves have been computed and an empirical formula has been derived, which allows the correction of the measured values of the sidelobes when the measurement range is below or around the far-field distance

ON THE EFFECTS OF IMMIGRATION ON HOST COUNTRIES

Starting from the consolidated literature on the labour market effects of immigration (summarized in the second chapter in what follows) the aims of this work are: (i) to assess the impact of skilled immigration on income in destination countries (chapter 3) and (ii) to understand the relation between immigration and offshoring when asymmetric information about foreing born workers is assumed (chapter 4). So, the rest of the thesis is composed follows: Chapter 2, "The economic impact of migration on host countries: a survey", provides a survey of the literature on the effects of migration on the economic performances in host countries. The aim of the chapter is to provide a synthetic view of both theoretical and empirical literature to better understand how host economies are affected by changes in their foreign born population endowment. The chapter is intended to clear the ground for the following chapters. Chapter 3, "Skilled migration and economic performances: evidence from OECD countries", investigates the effects of immigration flows and their human capital content on per capita GDP variation in 24 OECD host countries. Theoretical models conclude that the effect of immigrants in host country's income depends on the human capital content of migrants (Benhabib 1996); empirically the question is still open and this paper contributes to make light on this. So we propose an empirical estimation of the effects of immigrants and their human capital content on per capita GDP variation. Using an IV model to solve the endogeneity problem we found that high human capital content by immigrants has a positive effect on per capita GDP variation, but it is not enough to fully compensate the overall negative effects of migration on changes in per capita output. Chapter 4, "Offshoring, migrants and natives workers: the optimal choice under asymmetric information", presents a theoretical model about the optimal choice for a firm between offshoring and hiring immigrant workers under asymmetric information about their ability and effort in production (symmetric information is assumed about home born workers). When a domestic firm hires an immigrant it doesn't know his ability; while when the firm goes abroad it uses local agent in order to buy additional information about workers, thus enforceable contracts may be set. We show that it is optimal for firms to produce low quality products offshoring the production abroad, while intermediate quality level products will be produced at home using foreign born workers. Finally, high quality products will be produced using native workers

Assessment of neuroactive steroids in cerebrospinal fluid comparing acute relapse and stable disease in relapsing-remitting multiple sclerosis

Previous studies have reported an involvement of neuroactive steroids as neuroprotective and anti-inflammatory agents in neurological disorders such as multiple sclerosis (MS); an analysis of their profile during a specific clinical phase of MS is largely unknown. The pregnenolone (PREG), dehydroepiandrosterone (DHEA), and allopregnanolone (ALLO) profile was evaluated in cerebrospinal fluid (CSF) in relapsing-remitting multiple sclerosis (RR-MS) patients as well as those in patients affected by non-inflammatory neurological (control group I) and without neurological disorders (control group II). An increase of PREG and DHEA values was shown in CSF of male and female RR-MS patients compared to those observed in both control groups. The ALLO values were significantly lower in female RR-MS patients than those found in male RR-MS patients and in female without neurological disorder. During the clinical relapse, we observed female RR-MS patients showing significantly increased PREG values compared to female RR-MS patients in stable phase, while their ALLO values showed a significant decrease compared to male RR-MS patients of the same group. Male RR-MS patients with gadolinium-enhanced lesions showed PREG and DHEA values higher than those found in female RR-MS patients with gadolinium-enhanced lesions. Similary, male RR-MS patients with gadolinium-enhanced lesions showed PREG and DHEA values higher than male without gadolinium-enhanced lesions. Female RR-MS patients with gadolinium-enhanced lesions showed DHEA values higher than those found in female RR-MS patients with gadolinium-enhanced lesions. Male and female RR-MS patients with gadolinium-enhanced lesions showed ALLO values higher than those found in respective gender groups without gadolinium-enhanced lesions. ALLO values were lower in male than in female RR-MS patients without gadolinium-enhanced lesions. Considering the pharmacological properties of neuroactive steroids and the observation that neurological disorders influence their concentrations, these endogenous compounds may have an important role as prognostic factors of the disease and used as markers of MS activity such as relapses

Atorvastatin combined to interferon to verify the efficacy (ACTIVE) in relapsing-remitting active multiple sclerosis patients: a longitudinal controlled trial of combination therapy.

A large body of evidence suggests that, besides their cholesterol-lowering effect, statins exert anti-inflammatory action. Consequently, statins may have therapeutic potential in immune-mediated disorders such as multiple sclerosis. Our objectives were to determine safety, tolerability and efficacy of low-dose atorvastatin plus high-dose interferon beta-1a in multiple sclerosis patients responding poorly to interferon beta-1a alone. Relapsing–remitting multiple sclerosis patients, aged 18–50 years, with contrast-enhanced lesions or relapses while on therapy with interferon beta-1a 44 mg (three times weekly) for 12 months, were randomized to combination therapy (interferon+atorvastatin 20mg per day; group A) or interferon alone (group B) for 24 months. Patients underwent blood analysis and clinical assessment with the Expanded Disability Status Scale every 3 months, and brain gadolinium-enhanced magnetic resonance imaging at screening, and 12 and 24 months thereafter. Primary outcome measure was contrast-enhanced lesion number. Secondary outcome measures were number of relapses, EDSS variation and safety laboratory data. Forty-five patients were randomized to group A (n 1⁄4 21) or B (n 1⁄4 24). At 24 months, group A had significantly fewer contrast-enhanced lesions versus baseline (p 1⁄4 0.007) and significantly fewer relapses versus the two pre-randomization years (p < 0.001). At survival analysis, the risk for a 1-point EDSS increase was slightly higher in group B than in group A (p 1⁄4 0.053). Low-dose atorvastatin may be beneficial, as add-on therapy, in poor responders to high-dose interferon beta-1a alone

Multifocal Approach for Reflectarray Antenna for DTH Applications

In this paper, numerical and experimental results on the design of a multifocal, planar Reflectarray with scanning capabilities in both elevation and azimuth, are presented. The antenna is a possible alternative to the conventional parabolic reflectors in Direct-To-Home (DTH) receiving systems, with the planar reflector fixed to a building wall and the pointing obtained mechanically moving the feed to steer the main beam of the reflectarray

A voxel-based morphometry study of disease severity correlates in relapsing–remitting multiple sclerosis

Previous studies have shown a preferential loss of grey matter in fronto-temporal regions in patients with multiple sclerosis. Studies of correlates of disease severity are more controversial, because some studies have suggested an association between sensorimotor cortex atrophy and Expanded Disability Status Scale score, while others did not find such a correlation. The objective of this study was to assess the correlation of regional loss of grey matter and white matter with indexes of clinical and radiological severity in relapsing–remitting multiple sclerosis, including the Expanded Disability Status Scale and lesion load. Correlations between Expanded Disability Status Scale, lesion load and disease duration were assessed in 128 patients with relapsing–remitting multiple sclerosis (Expanded Disability Status Scale range 1.0–6.0) using optimized voxel-based morphometry. Bilateral loss of grey matter in sensorimotor cortices was correlated with Expanded Disability Status Scale, and tissue loss also involved adjacent white matter, extending along pyramidal tracts to the brainstem. Increasing lesion load was correlated with loss of deep grey matter and white matter. No specific region of grey matter or white matter showed a significant correlation with disease duration. These findings support the hypothesis that motor neuron involvement plays a major role in the progression of physical disability. Lesion load accrual affects mainly highly interconnected subcortical structures, while disease duration has a less significant impact on brain atrophy, probably owing to the inter-subject heterogeneity of the clinical course of the disease

Treatment with gonadotropin releasing hormone agonists in systemic lupus erythematosus patients receiving cyclophosphamide: a long-term follow-up study

Background: Cyclophosphamide treatment has been associated with ovarian function impairment. Co-treatment with gonadotropin-releasing hormone-analogue (GnRH-a) seems to be able to prevent this complication. However, even though data are available on neoplastic patients, limited data have been published on systemic lupus erythematosus (SLE) women cohorts. Objectives: To evaluate GnRH-a efficacy on ovarian function preservation in SLE women receiving cyclophosphamide treatment. Methods: The authors performed a retrospective study including SLE women requiring cyclophosphamide treatment and compared those treated with and without GnRH-a (case and controls, respectively). All patients were evaluated before cyclophosphamide treatment and every 3 months in the following years. Ovarian function was evaluated using hormonal profiles. Results: The study comprised 33 SLE cyclophosphamide-treated women: 18 co-treated with triptorelin, and 15 controls. The mean follow-up was 8.1 ± 5.1 years (range 4–11). Premature ovarian failure (POF) prevalence was significantly lower in SLE women treated by cyclophosphamide plus triptorelin compared to controls (11.1% vs. 33.3%, P = 0.0002). The occurrence of POF was significantly associated with higher age at the time of cyclophosphamide treatment (P = 0.008). Only patients in the GnRH-a treated group had successful pregnancies. Conclusions: The study provides information about the efficacy of co-treatment with GnRH-a in SLE women receiving cyclophosphamide, as demonstrated by the lower POF incidence compared to untreated subjects, based on long-term follow-up. These results reinforce the use of GnRH-a for fertility preservation in premenopausal SLE patients treated by cyclophosphamide