The Credibility of the Exchange Rate Regime: An Analysis trough “Derivatives” of the September 1992 Crisis

This paper argues that, in the September 1992 European currency crisis, market trends in derivatives, in terms of price volatility and change in volumes traded, might have represented an early indicator, in reference to the spot market, of the lack of confidence in the ability of the Italian Lira and the Sterling Pound to maintain their parities within the ERM. The assessment is made by comparing the daily data on Italian/English interbank rates with the implicit yield on short-term interest rate futures and with a maximum compatible with the ERM band created by means of German interbank rates and changes in the exchange ratesDerivatives; Exchange rates; Volatility

The Credibility of the Exchange Rate Regime: An Analysis trough “Derivatives” of the September 1992 Crisis

This paper argues that, in the September 1992 European currency crisis, market trends in derivatives, in terms of price volatility and change in volumes traded, might have represented an early indicator, in reference to the spot market, of the lack of confidence in the ability of the Italian Lira and the Sterling Pound to maintain their parities within the ERM. The assessment is made by comparing the daily data on Italian/English interbank rates with the implicit yield on short-term interest rate futures and with a maximum compatible with the ERM band created by means of German interbank rates and changes in the exchange rate

The Credibility of the Exchange Rate Regime: An Analysis trough “Derivatives” of the September 1992 Crisis

This paper argues that, in the September 1992 European currency crisis, market trends in derivatives, in terms of price volatility and change in volumes traded, might have represented an early indicator, in reference to the spot market, of the lack of confidence in the ability of the Italian Lira and the Sterling Pound to maintain their parities within the ERM. The assessment is made by comparing the daily data on Italian/English interbank rates with the implicit yield on short-term interest rate futures and with a maximum compatible with the ERM band created by means of German interbank rates and changes in the exchange rate

Infusion of casein hydrolizates into the mammary gland simulates the omission of one daily milking in goats

Suppression of one daily milking at weekends, even though socially desirable, may reduce milk yield. These losses have been attributed to a short-term mechanism: the filling of the cistern and ductal-alveolar system with milk which contains a peptide called feedback inhibitor of lactation (FIL) (Wilde and Peaker, 1990). The FIL probably reduces the synthesis and secretion of mammary cells by blocking the potassium channel of the apical membrane (Silanikove et al., 2000). Shamay et al. (2002) hypothesized that the FIL can be identified with the AA sequence 1-28, derived from the breakdown of β-casein by plasmin (PL). The aim of this work was to verify if the infusion of casein hydrolizates (CNH) into the mammary gland simulates the omission of one milking for two consecutive days

Can People Sleep Too Much? Effects of Extended Sleep Opportunity on Sleep Duration and Timing

Many people are concerned about whether they are getting “enough” sleep, and if they can “sleep too much.” These concerns can be approached scientifically using experiments probing long-term (i.e., multi-night) sleep homeostatic processes, since homeostatic processes move the system toward its physiological setpoint (i.e., between “not enough” and “too much”). We analyzed sleep data from two human studies with sleep opportunities much longer than people usually stay in bed (i.e., conditions in which sleep homeostatic responses could be documented): sleep opportunities were 14–16 h per day for 3–28 days. Across the nights of the extended sleep opportunities, total sleep duration, Rapid Eye Movement (REM) sleep duration and non-REM sleep durations decreased and sleep latency increased. Multiple nights were required to reach approximately steady-state values. These results suggest a multi-day homeostatic sleep process responding to self-selected insufficient sleep duration prior to the study. Once steady state-values were reached, there were large night-to-night variations in total sleep time and other sleep metrics. Our results therefore answer these concerns about sleep amount and are important for understanding the basic physiology of sleep and for two sleep-related topics: (i) the inter-individual and intra-individual variability are relevant to understanding “normal” sleep patterns and for people with insomnia and (ii) the multiple nights of sleep required for recovery from insufficient sleep from self-selected sleep loss is important for public health and other efforts for reducing the adverse effects of sleep loss on multiple areas of physiology

Multiple vertebral hemangiomas of the thoracic spine with atypical radiological features and aggressive behavior causing myelopathy: A case report

Abstract Background Vertebral Haemangiomas (VHs) are frequent and generally asymptomatic benign tumors, involving the spine, usually incidentally found on computed tomography and magnetic resonance. Despite being usually asymptomatic and quiescent lesions, VHs can occasionally manifest aggressive features, leading to clinical manifestations such as back pain and neurological deficits. Case report. We report a case of a 54-year-old man, presented with 5 months history of pain, associated with lower limbs paraesthesia and weakness, gait disturbance and episodes of accidental falls. Radiological evaluation by spine pre- and post-contrast MRI indicated multiple vertebral hypervascular lesions, compatible with haemangiomas, involving from T3 to T11 levels, showing several different features (typical and atypical); aggressive haemangioma radiological pattern may be valuable at T3 and T4 vertebras. A thoracic spine pre- and post-contrast computed tomography confirmed the radiological diagnosis of multiple aggressive haemangiomas. Discussion Aggressive VH consists in a very rare subset of vertebral haemangiomas characterized by a greater tendency in being symptomatic. They may show atypical radiological features, that make their diagnosis very complex. In the recent years, many strategies for treatment of symptomatic or aggressive VHs have been developed, but the optimal treatment strategy is still controversial. Conclusion Although aggressive VHs being extremely rare, recognizing radiological features of these lesions is mandatory to achieve a correct diagnosis and appropriate therapeutic targets

Accuracy assessment of an industrial actuator

A commercial linear actuator equipped with a 0.1 μm resolution encoder was used as a contact displacement sensor with adjustable force. The accuracy of the position reading of the actuator was evaluated from experimental data taking into account the uncertainty contributions. The tests consisted of length measurements of grade 0 steel gauge blocks. Measurements with different values of contact force were performed to assess its influence. A statistical analysis of the experimental data was performed to support the accuracy assessment. Systematic effects were identified and corrected. An expanded uncertainty (k=2) lower than 1 μm was estimated

Validation of a questionnaire about knowledge and perception of biological risk among biomedical students of Sapienza University of Rome

Background and aim. Healthcare workers and Biomedical students are continuously exposed to biological risk in their clinical practice. The objective of this study was to evaluate the validity and reliability of an Italian questionnaire on the knowledge and perception of biological risk in Biomedical students at the beginning of their professional training. Material and methods.An electronic questionnaire was administered to students attending the second semester of the first year of Biomedical Courses at Sapienza University of Rome. The questionnaire consists of 40 questions divided into five sections collecting sociodemographic data, health status and level of knowledge and perception of biological risk. The statistical analysis was performed with Statistical Package for Social Sciences (SPSS) version 25. Results. A total of 309 individuals answered the online questionnaire, with a response rate of 83.5%. The analysis of internal consistency was performed by two dichotomous variables that measured the knowledge level on hygiene behaviour and gloves use. The analysis showed a standardized Cronbach’s alpha equal to 0.765, corresponding to a good reliability. A better reliability was found out among physiotherapy and medical students, with a Cronbach’s alpha equal to 0.944 and 0.881, respectively. Regarding vaccines, 97.7% of the sample was given a Hepatitis B vaccination and 98.7% of students consider vaccinations essential for healthcare workers. Conclusion. Results of Cronbach’s alpha showed a good reliability of the questionnaire. First-year Biomedical students may be exposed to occupational biological risk mainly because of their inexperience. A training educational path should be implemented in order to acquire competences, knowledge, attitudes and practical skills, correct behaviors and a personal and professional responsibility

FBR for Polyolefin Production in Gas Phase: Validation of a Two-phase Compartmentalized Model by Comparison with CFD

Two different modeling approaches are applied in this work to the simulation of fluidized bed reactors containing solid particles of Geldart A-B type and operated at conditions typically used for polyolefins production. On one side, a fully detailed computational fluid dynamics (CFD) model is developed, considering a 2D planar geometry and a multi-fluid description with kinetic theory of granular flows. On the other, a conventional three-phase, 1D compartmentalized model (SCM) is also developed, implementing the fluid dynamic description based on popular, semi-empirical relationships available in the literature. Given the huge difference of computational effort associated with the corresponding numerical solutions, our aim is to confirm the reliability of the simplified model by comparison with the results of the detailed CFD model. The comparison is carried out considering the fluidization of a bed of solid particles without reaction and solid injection or withdrawal, thus focusing on the steady-state fluid dynamic behavior of the expanded bed. Three different gas velocities and different monodisperse and polydisperse particle populations are analyzed. The results show that the oversimplified compartmentalized approach is capable to predict the solid mixing features established inside the reactor operated in bubbling fluidization regime with good reliability for non-reactive polyethylene particles. Average solid volume fractions are particularly close to the values predicted by the CFD model when monodisperse particles are considered inside the examined range of gas velocity values. A generally good agreement is also found when solids with broad size distribution are analyzed. Overall, these comparisons provide a meaningful validation of the simplified compartmentalized models: given their negligible computational demand and general versatility (complex kinetic schemes and single particle models are easily accounted for), they still represent an effective tool of industrial process design

Comparison between detailed (CFD) and simplified models for the prediction of solid particle size distribution in fluidized bed reactors

This work is aimed at developing a simplified model suitable to effectively describe the fluidization behavior within fluidized beds with minimal computational efforts. The simplified model was validated through detailed CFD Euler-Euler simulations showing a good agreement in the case of large particles (about 450 micron) at all the gas velocities considered (20, 40, 61 cm/s). Slightly less accurate outcomes were observed for smaller particles (about 220 micron). This was due to the underestimation of the particle size effect on the fluidization behavior by the simplified approach