Measurement of the ratio h/e with a photomultiplier tube and a set of LEDs

We propose a laboratory experience aimed at undergraduate physics students to understand the main features of the photoelectric effect and to perform a measurement of the ratio h/e, where h is the Planck's constant and e is the electron charge. The experience is based on the method developed by Millikan for his measurements on the photoelectric effect in the years from 1912 to 1915. The experimental setup consists of a photomultiplier tube (PMT) equipped with a voltage divider properly modified to set variable retarding potentials between the photocathode and the first dynode, and a set of LEDs emitting at different wavelengths. The photocathode is illuminated with the various LEDs and, for each wavelength of the incident light, the output anode current is measured as a function of the retarding potential applied between the cathode and the first dynode. From each measurement, a value of the stopping potential for the anode current is derived. Finally, the stopping potentials are plotted as a function of the frequency of the incident light, and a linear fit is performed. The slope and the intercept of the line allow respectively to evaluate the ratio h/e and the ratio W/e, where W is the work function of the photocathode.Comment: 14 pages, 4 figure

Role of heat and mechanical treatments in the fabrication of superconducting Ba0.6K0.4Fe2As2 ex-situ Powder-In-Tube tapes

Among the recently discovered Fe-based superconducting compounds, the (K,Ba)Fe2As2 phase is attracting large interest within the scientific community interested in conductor developments. In fact, after some years of development, critical current densities Jc of about 105 A/cm2 at fields up to more than 10 T have been obtained in powder in tube (PIT) processed wires and tapes. Here we explore the crucial points in the wire/tape fabrication by means of the ex-situ PIT method. We focus on scaling up processes which are crucial for the industrial fabrication. We analyzed the effects on the microstructure of the different heat and mechanical treatments. By an extensive microstructural analysis correlated with the transport properties we addressed the issues concerning the phase purity, the internal porosity and crack formation in the superconducting core region. Our best conductors with a filling factor of about 30 heat treated at 800 C exhibited Tc = 38 K the highest value measured in such kind of superconducting tape. The microstructure analysis shows clean and well connected grain boundaries but rather poor density: The measured Jc of about 3 x 10^4 A/cm2 in self-field is suppressed by less than a factor 7 at 7 T. Such not yet optimized Jc values can be accounted for by the reduced density while the moderate in-field suppression and a rather high n-factor confirm the high homogeneity and uniformity of these tapes

A new methodology to evaluate Human Workload State Inference

Electronics and automation are increasingly part of our daily lives, and led to the introduction of systems and intelligent machines to which the human work is delegated and that collaborate and support the user in the conduct of mancritical operations. The University of Modena and Reggio Emilia is partner of the european project “Designing Dynamic Distributed Cooperative Human-Machine Systems” (D3CoS, www.d3cos.eu), that aim is the definition of affordable methods, techniques and tools which go beyond assistance systems and consequently address the specification, development and evaluation of cooperative systems from a multi-agent perspective where human and machine agents are in charge of common tasks, assigned to the system as a whole. The key on which to base the cooperation between the machine and the human is the amount of workload of the human operator. So we were involved into investigate aspects of the functional state of human operators interacting with the demonstrator in the unmanned aerial vehicle (UAV) and maritime domains. We analyzed and correlated objective psycho-physiological measures: eye blinks, respiration rate and amplitude, electro dermal activity, heart rate variability, blood pressure; with subjective self-assessed measure evaluated with two questionnaires: NASA-TLX and Rating Scale Mental Effort (RSME); with the aim to realize a mathematical regression model for classifying the mental operators workload. Keywords— Workload, psycho-physiological measures, statistical analysis, cooperative systems

Dietary cadmium intake and risk of cutaneous melanoma: a population-based case-control study in Northern Italy

BACKGROUND AND AIM. Cadmium is a toxic heavy metal for humans, and its environmental exposure has been linked to many adverse health effects, including cancer, atherosclerosis and diabetes. In particular, recent findings suggest that cadmium may increase risk of cutaneous melanoma, possibly through the promotion of the malignant transformation of melanoma cells through aberrant DNA methylation and by inducing gene expression dysregulation. Since in non-occupational exposed and non-smoking subjects dietary exposure is the major source of cadmium exposure, we aimed to assess melanoma risk in relation to dietary cadmium intake. METHODS. We recruited 380 newly-diagnosed incident cases of cutaneous melanoma and 719 sex- and age-matched population controls in four North Italian provinces (Parma, Reggio Emilia, Modena, and Bologna) of Emilia-Romagna Region. We estimated their dietary habits using a semi-quantitative food frequency questionnaire and we evaluated melanoma risk by computing the odds ratio (OR) and its 95% confidence interval (CI) according to quintile distribution of cadmium intake. We used a conditional logistic regression model to compute ORs, matching by sex, age and province of residence, and adjusting also for phototype, non-alcoholic energy intake, body mass index, and Italian Mediterranean Diet Index. Also a spline regression model was used in order to evaluated possible dose-response relation. RESULTS: Median cadmium intake was 5.81 µg/day (interquartile range 4.46-7.59) in cases, and 5.63 µg/day (4.46-7.34) in controls. OR of melanoma associated with 1-unit increase in cadmium intake was 1.11 (95% CI 1.00-1.24). Melanoma risk increased with increasing quintile of cadmium exposure, with ORs of 1.55 (95% CI 0.99-2.42), 1.54 (95% CI 0.99-2-40), 1.75 (95% CI 1.12-2.75), and 1.65 (95% CI 1.05-2.61) from second to highest quintile compared to lowest quintile. Sex-stratified analysis showed substantially comparable results and a generally higher risk in women, with continuous ORs of 1.10 (95% CI 0.93-1-29), and 1.15 (95% CI 0.99-1.33) in men and women, respectively. Spline regression analysis showed a non-linear risk increase, with possible plateau at 5-6 µg/day of cadmium intake. Slightly higher risk estimates in women and older subjects were detected. CONCLUSIONS: Our results seem to point out a positive association between dietary cadmium exposure and melanoma risk in the study population. Such association started to occur at a level of exposure lower than the tolerable intake established for food safety by international authorities

Dietary cadmium exposure and risk of melanoma: an Italian population-based case-control study

Background and aim. The heavy metal cadmium could be highly toxic to humans, and its environmental exposure has been linked to many adverse health effects, such as atherosclerosis, diabetes, and cancer, including melanoma. Although the underlying mechanisms need yet to be clearly identified, recent findings suggested that cadmium can specifically promote the malignant transformation of melanoma cells through the aberrant DNA methylation inducing dysregulation of specific gene expression. Since in the non-occupationally exposed population, in addition to smoking, food intake is the major source of cadmium exposure, we aimed at assessing the risk of cutaneous melanoma in relation to dietary cadmium intake. Methods. Using a population-based study design, we recruited 380 incident cases of newly-diagnosed melanoma and 719 sex- and age-matched controls in the Emilia-Romagna Region, Northern Italy. We evaluated their dietary habits through a semi-quantitative food frequency questionnaire and we computed the odds ratio (OR) and its 95% confidence interval (CI) for melanoma according to quintile distribution of cadmium intake, using a conditional logistic regression model, matching by sex, age and province of residence, and adjusting also for phototype, non-alcoholic energy intake, body mass index, and Italian Mediterranean Diet Index. Results: Median intake of cadmium was 5.81 µg/day (interquartile range 4.46-7.59) in cases, and 5.63 µg/day (4.46-7.34) in controls. OR of melanoma associated with 1-unit increase in cadmium intake was 1.11 (95% CI 1.00-1.24). Melanoma risk increased with increasing quintile of cadmium exposure, with ORs of 1.55 (95% CI 0.99-2.42), 1.54 (95% CI 0.99-2-40), 1.75 (95% CI 1.12-2.75), and 1.65 (95% CI 1.05-2.61) in the second to the highest quintile compared to the lowest quintile. Sex-stratified analysis showed substantially comparable results and a generally higher risk in female population, with continuous ORs of 1.10 (95% CI 0.93-1-29), and 1.15 (95% CI 0.99-1.33) in men and women, respectively. Conclusions: Our results suggest a positive association between cadmium exposure through diet and risk of cutaneous melanoma in a Northern Italy population. Such association started to occur at a level of exposure lower than the tolerable intake established by the World Health Organization, and considered to be safe for humans

Quarantine and Isolation during COVID-19 outbreak: A case of online diagnosis of supraventricular arrhythmia through telemedicine

The present case report highlights the usefulness of telemedicine during quarantine and isolation. The patient developed a supraventricular arrhythmia, and the diagnosis and management of the arrhythmia was done online

Effect of grain refinement on enhancing critical current density and upper critical field in undoped MgB2 ex-situ tapes

Ex-situ Powder-In-Tube MgB2 tapes prepared with ball-milled, undoped powders showed a strong enhancement of the irreversibility field H*, the upper critical field Hc2 and the critical current density Jc(H) together with the suppression of the anisotropy of all of these quantities. Jc reached 104 A/cm2 at 4.2 K and 10 T, with an irreversibility field of about 14 T at 4.2 K, and Hc2 of 9 T at 25 K, high values for not-doped MgB2. The enhanced Jc and H* values are associated with significant grain refinement produced by milling of the MgB2 powder, which enhances grain boundary pinning, although at the same time also reducing the connectivity from about 12% to 8%. Although enhanced pinning and diminished connectivity are in opposition, the overall influence of ball milling on Jc is positive because the increased density of grains with a size comparable with the mean free path produces strong electron scattering that substantially increases Hc2, especially Hc2 perpendicular to the Mg and B planes.Comment: 26 pages, 9 figures, submitted to J. Appl. Phy

The immuneregulator role of neprilysin (NEP) in invertebrates

Neprilysin (NEP) represents an important enzyme in both vertebrates and invertebrates. In the present report we have focused our attention to invertebrates. In particular, a structure related to CD10/NEP as well as its activity in different tissues, such as immunocytes, nervous tissue and muscle of various species were detected. Moreover, the role played by the enzyme in the interactions between host and parasite has also been reported. The findings indicate that NEP immunoregulation is a well-balanced process that, with appropriate physiological and homeostatic responses to challenges, allows the survival and well-being of the species