Advances plasma sources for space applications

A Helicon thruster is an electrical propulsion system where the plasma source, i.e. Helicon source, is a dielectric tube surrounded by coils generating a weak magneto-static field (up to 0.15 T), and a radio frequency antenna working in the range of frequencies 1-50 MHz that drives the discharge. The propulsive figures of merit of a Helicon thruster (e.g. specific impulse) depend on plasma parameters (e.g. plasma density), that are in turn related to the power deposited by the antenna into the plasma. A similar plasma source can be exploited in gaseous plasma antennas, devices that rely on a partially or fully ionized gas to radiate electromagnetic waves. Plasma antennas might offer several advantages with respect to conventional antennas that make them suitable for space communications. As far as plasma antennas are concerned, their performances (e.g. gain) are related to the discharge parameters (i.e. the plasma density, the neutral pressure), and so to the efficiency of the plasma generation system. Regardless the differences in shape, field of application, and working condition, Helicon thrusters and plasma antennas share the same physical problems, namely: (i) wave propagation, (ii) power deposition, and (iii) transport of charged particles within the plasma source. To solve the wave-plasma coupling, we relied on ADAMANT, a full-wave frequency domain tool that takes into account the plasma effect as a polarization current. By means of this tool, we numerically assessed the radiation properties of the simplest plasma antenna configuration, a plasma dipole. We numerically verified that a plasma dipole can feature the same current distribution of a conventional metal dipole, and found that the plasma density, and the neutral pressure are the main parameters driving the plasma antenna performances. To understand the equilibrium conditions of a plasma source, we coupled ADAMANT with a 0-D fluid solver. This new numerical tool was exploited to design, and realize several custom-made plasma sources. This new approach allowed us to explore several combinations of gases, background pressures, and geometries without any constraints related to commercially available sources. By means of a microwave interferometer, we measured the plasma density, and its distribution along the sources. One of these sources was exploited in one of the very first prototypes of plasma antenna working in the GHz regime. The plasma dipole has been tested in an open environment for the gain pattern, and value; these results are in good accordance with the simulation results. Nevertheless, the maximum gain of the plasma dipole is lower by the 57% than the gain of a conventional dipole antenna in same conditions. This is due to a high pressure level, and a low plasma density of the source exploited in the plasma dipole, that lead to low conductance, and high losses within the plasma discharge

CONTROL OF MOTOR UNITS DURING VOLUNTARY FORCE-PRODUCTION: IMPLICATIONS FOR EXERCISE

We have recently developed a technology that enables studies of the firing properties of a large set (typically 30 to 40) of concurrently active motor units during isometric voluntary contractions ranging from low force levels to maximal voluntary contractions (MVC). With this technology we have executed studies to investigate the behavior of the firing rates of motor units as a function of their recruitment properties during contractions at various force levels. We found that the firing rates have a hierarchical structure wherein the firing rate value of motor units is inversely related to their recruitment threshold, with earlier recruited motor units having greater firing rates at any time and any force level during a contraction. This relationship does not support the opposite notion that has been generally held for the past five decades. Knowing the structure of the firing behavior of motor units during voluntary contractions provides guidance for understanding the performance of muscles during exercise and sports

Parental bonding and personality disorder: The mediating role of alexithymia

This study explored whether alexithymic features mediate the effect of perceived adverse parenting during childhood on being diagnosed with a PD in adulthood. Two hundred sixty-five psychiatric outpatients were evaluated with the Toronto Alexithymia Scale (TAS-20), the Parental Bonding Instrument (PBI), the Structured Interview for DSM-IV Personality, the Structured Clinical Interview for DSM-IV Axis I Disorders, the Clinical Global Impression scale, and the Global Assessment of Functioning scale. The statistical model for mediation proposed by Baron and Kenny (1986) was employed to detect whether the TAS scores account for the relation between PBI scores and a PD diagnosis. The results indicated that although altered parental bonding (and specifically, excessive maternal protection) may enhance the risk of PD, its effect is completely mediated by the alexithymic feature Difficulty Describing Feelings to Others (DDF), after controlling for gender, age, educational level, type, severity and age of onset of Axis I disorders. Therefore, this study suggests that the presence of DDF accounts for the effect of maternal overprotection risk factor for PD. © 2008 The Guilford Press

Mammographic breast density in infertile and parous women

BACKGROUND: Mammographic breast density is a useful marker for breast cancer risk, as breast density is considered one of the strongest breast cancer risk factors. The study objective was to evaluate and compare mammographic breast density in infertile and parous women, as infertility may be associated with high breast density and cancer occurrence. METHODS: This study evaluated mammographic breast density using two different systems, BIRADS and Boyd. A selected patient population of 151 women with primary infertility (case group) was compared to 154 parous women who had at least one previous pregnancy (control group). Both groups were premenopausal women aged ≥ 35. RESULTS: Evaluation of mammographic features showed that 66.9% of case group patients and 53.9% of control group patients were classified BIRADS-3/BIRADS-4; p < 0.05. Adjusted Odds ratio for the case group in the categories BIRADS-3/BIRADS-4 was 1.78 (95% CI: 1.10-2.89). Using the Boyd classification system, 53.6% of case group patients and 31.8% of control group patients were classified E/F; p < 0.05. Adjusted Odds ratio for case group patients in Boyd categories E/F was 2.05 (95 % CI: 1.07-3.93). CONCLUSIONS: Both systems yielded a higher percentage of increased breast density in the case group. Boyd and BIRADS classification systems indicate to what extend breast cancer lesions may be missed on mammography due to masking by dense tissue. Therefore, patients with a high BIRADS or Boyd score should undergo further investigation

Comparative study of gene expression by cDNA microarray in human colorectal cancer tissues and normal mucosa

The causative molecular pathways underlying the pathogenesis of colorectal cancer (CRC) need to be better characterized. The purpose of our study was to better understand the genetic mechanism of oncogenesis for human colorectal cancer and to identify new potential tumor markers of use in clinical practice. We used cDNA microarrays to compare gene expression profiles of colorectal biopsies from 25 CRC patients and 13 normal mucosa from adjacent non-cancerous tissues. Findings were validated by real-time PCR; in addition, western blotting and immunochemistry analysis were carried out as further confirmation of differential expression at a protein level. Comparing cancerous tissues with normal colonic mucosa we identified 584 known genes differentially expressed to a significant degree (p<0.001). Many of the transcripts that were more abundant in tumors than in non-neoplastic tissues appear to reflect important events for colon carcinogenesis. For example, a significant number of these genes serve as apoptotic inhibitors (e.g. BFAR, BIRC1, BIRC6). Furthermore, we observed the simultaneous up-regulation of HLA-E and the down-regulation of beta2-microglobulin; these genes strongly support a potential tumor escape strategy from immune surveillance in colon cancer tissues. Our study provides new gene candidates in the pathogenesis of human CRC disease. From our results we hypothesize that CRC cells escape immune surveillance through a specific gene expression alteration; moreover, over-expression of several survival genes seems to confer a more anti-apoptotic phenotype. These genes are involved in pathways not previously implicated in CRC pathogenesis and they may provide new targets for therapy.Fil: Bianchini, Michele. Fundación P/la Invest.y Prevención del Cancer. Centro de Investigaciones Oncologicas; ArgentinaFil: Levy, Estrella Mariel. Fundación P/la Invest.y Prevención del Cancer. Centro de Investigaciones Oncologicas; Argentina. Universidad de Buenos Aires; ArgentinaFil: Zucchini, Cinzia. Università di Bologna; ItaliaFil: Pinski, Victor. Universidad de Buenos Aires; ArgentinaFil: Macagno, Carlo. Universidad de Buenos Aires; ArgentinaFil: De Sanctis, Paola. Università di Bologna; ItaliaFil: Valvassori, Luisa. Università di Bologna; ItaliaFil: Carinci, Paolo. Università di Bologna; ItaliaFil: Mordoh, Jose. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Bioquímicas de Buenos Aires. Fundación Instituto Leloir. Instituto de Investigaciones Bioquímicas de Buenos Aires; Argentina. Fundación P/la Invest.y Prevención del Cancer. Centro de Investigaciones Oncologicas; Argentin

Asimmetria del rischio sistematico dei titoli immobiliari americani: nuove evidenze econometriche

In this work we have found a relevant increase in the systematic risk of the American real estate securities in the year 2007 which go to the initial values in the year 2009. With the aim to evaluate the systematic risk we have used the Fama-French three factor model and we have studied the relationship between the extra-return of the REIT index where we have used as proxy the American real estate securities and the extra return of the S&P500 index representative by the market portfolio return. The results confirmed the presence of an “Asymmetric Beta Puzzle” in agreement with other previous studies. At the same time the results have shown that the REIT securities behaved as speculative securities. In the past the same securities were considered conservative in the year of the subprime crisis. The REIT securities in particular have amplified arriving to double the variations of the market risk premium

Asimmetria del rischio sistematico dei titoli immobiliari americani: nuove evidenze econometriche

In this work we have found a relevant increase in the systematic risk of the American real estate securities in the year 2007 which go to the initial values in the year 2009. With the aim to evaluate the systematic risk we have used the Fama-French three factor model and we have studied the relationship between the extra-return of the REIT index where we have used as proxy the American real estate securities and the extra return of the S&P500 index representative by the market portfolio return. The results confirmed the presence of an “Asymmetric Beta Puzzle” in agreement with other previous studies. At the same time the results have shown that the REIT securities behaved as speculative securities. In the past the same securities were considered conservative in the year of the subprime crisis. The REIT securities in particular have amplified arriving to double the variations of the market risk premium

Validation of the Treadmill Six-Minute Walk Test in People Following Cardiac Surgery

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What Else Is Needed to Improve Survival from Out-of-Hospital Cardiac Arrest to Hospital Admission? Data from a Prospective Registry for the Years 2020-2023 in the Italian Province of Varese

Around the world, data on out-of-hospital cardiac arrest (OHCA) are heterogeneous in terms of outcomes and reporting, and not all registries follow the Utstein recommendations for uniform OHCA data collection. This study reports data on OHCA occurring in recent years in a limited territory to analyze, in a homogenous setting, the circumstances and interventions affecting survival to hospital admission. OHCA data from the province of Varese for the years 2020-2022 were extracted from a prospective registry. For survival to hospital admission, the impact of pandemic waves and variables known to affect survival was evaluated both in the overall population and in the subgroup of patients in whom cardiopulmonary resuscitation (CPR) was initiated or continued by the emergency medical service (EMS). Overall, 3263 OHCAs occurred mainly at home (88%), with a time to intervention of 13.7 min, which was significantly longer during lockdown (15.7 min). Bystanders performed CPR in 22% of the cases and used automatic external defibrillator (AED) in 2.2% of the cases. Overall survival to hospital admission was 7.7%. In the multivariate analysis, in the general population, occurrence near a public building (OR 1.92), the presence of witnesses (OR 2.65), and a shockable rhythm (OR 7.04) were independent predictors of survival to hospital admission, whereas age (OR 0.97) and occurrence during a pandemic wave (OR 0.62) were associated with significantly worse survival to hospital admission. In the group of patients who received CPR, AED shock by bystanders was the only independent predictor of survival (OR 3.14) to hospital admission. Among other factors, early defibrillation was of crucial importance to improve survival to hospital admission in possibly rescuable patients. The occurrence of OHCA during pandemic waves was associated with longer intervention time and worse survival to hospital admission