La storia infinita delle pressioni estremamente basse e della loro misura

Lo scopo della presente nota è quello di dare un panorama storico dello sviluppo della fisica e tecnologia del vuoto e delle inter-connessioni tra la sua misura ed i metodi per ottenere pressioni estremamente basse, quindi prospettare brevemente la situazione attuale

La storia infinita delle pressioni estremamente basse e della loro misura

Lo scopo della presente nota è quello di dare un panorama storico dello sviluppo della fisica e tecnologia del vuoto e delle inter-connessioni tra la sua misura ed i metodi per ottenere pressioni estremamente basse, quindi prospettare brevemente la situazione attuale

WOMEN – SCIENCE – TECHNOLOGY: ANALYSIS OF A CASE STUDY

Nowadays, a very little attention has been dedicated to gender studies in science and technology. In particular, very few researches deal with women vertical, but also orizontal, segregation in public research institutions. The main purpose of this work is to analyze the phenomenon of glass ceiling within an Italian public research labs which operate in Technological Science. The methodology applied is based on the narrative interview, applied to one of the biggest Technological Research Institute inside the National Research Council of Italy. This study shows tree main results: 1) gender identity; 2) social construction of science; 3) organizational culture of gender. Moreover another important factor has emerged: the freeze of careers. In fact it stops the possibility to actuate any kind of management actions against glass ceiling. Some concluding remarks ended this works.Women, Career, Science, Technology, Glass ceiling, Bottle neck

Modular Synthesis of α,α-Diaryl α-Amino Esters via Bi(V)-Mediated Arylation/SN2-Displacement of Kukhtin–Ramirez Intermediates

We report a concise and modular approach to α,α-diaryl α-amino esters from readily available α-keto esters. This mild, one-pot protocol proceeds via ketone umpolung, with in situ formation of a Kukhtin–Ramirez intermediate preceding sequential electrophilic arylation by Bi(V) and SN2 displacement by an amine. The methodology is compatible with a wide range of anilines and primary amines - including derivatives of drugs and proteinogenic amino acids - Bi(V) arylating agents, and α-keto ester substrates

How accurate is an LCD screen version of the Pelli–Robson test?

Purpose: To evaluate the accuracy and repeatability of a computer-generated Pelli–Robson test displayed on liquid crystal display (LCD) systems compared to a standard Pelli–Robson chart. Methods: Two different randomized crossover experiments were carried out for two different LCD systems for 32 subjects: 6 females and 10 males (40.5 ± 13.0 years) and 9 females and 7 males (27.8 ± 12.2 years), respectively, in the first and second experiment. Two repeated measurements were taken with the printed Pelli–Robson test and with the LCDs at 1 and 3 m. To test LCD reliability, measurements were repeated after 1 week. Results: In Experiment 1, contrast sensitivity (CS) measured with LCD1 resulted significantly higher than Pelli–Robson both at 1 and at 3 m of about 0.20 log 1/C in both eyes (p < 0.01). Bland–Altman plots showed a proportional bias for LCD1 measures. LCD1 measurements showed reasonable repeatability: ICC was 0.83 and 0.65 at 1 and 3 m, respectively. In Experiment 2, CS measured with LCD2 resulted significantly lower than Pelli–Robson both at 1 and at 3 m of about 0.10 log 1/C in both eyes (p < 0.01). Bland–Altman plots did not show any proportional bias for LCD2 measures. LCD2 measurements showed sufficient repeatability: ICC resulted 0.51 and 0.65 at 1 and 3 m, respectively. Conclusions: Computer-generated versions of Pelli–Robson test, displayed on LCD systems, do not provide accurate results compared to classic Pelli–Robson printed version. Clinicians should consider that Pelli–Robson computer-generated versions could be non-interchangeable to the printed version

The effect of hydrogel and silicone hydrogel contact lenses on the measurement of intraocular pressure with rebound tonometry

Purpose: To assess the accuracy of intraocular pressure(IOP) measurements using rebound tonometry over disposable hydrogel (etafilcon A) and silicone hydrogel (senofilcon A) contact lenses (CLs) of different powers. Methods: The experimental group comprised 36 subjects (19 male, 17 female). IOP measurements were undertaken on the subject’s right eyes in random order using a rebound tonometer (ICare). The CLs had powers of +2.00D, −2.00D and−6.00D. Six measurements were taken over each contact lens and also before and after the CLs had been worn. Results: A good correlation was found between IOP measurements with and without CLs (all r≥0.80; p < 0.05). Bland Altman plots did not show any significant trend in the difference in IOP readings with and without CLs as a function of IOP value. A two-way ANOVA revealed a significant effect of material and power (p < 0.01) but no interaction. All the comparisons between the measurements without CLs and with hydrogel CLs were significant (p < 0.01). The comparisons with silicone hydrogel CLs were not significant. Conclusions: Rebound tonometry can be reliably performed over silicone hydrogel CLs. With hydrogel CLs, the measurements were lower than those without CLs. However, despite the fact that these differences were statistically significant, their clinical significance was minimal

L’accelerazione di gravità

Un esempio particolare di accelerazione è rappresentato dall’accelerazione di gravità che, come è noto, è connessa con l’esistenza di una forza d’attrazione che un corpo esercita su di un altro. L' accelerazione subita da un corpo per effetto di un altro corpo posto ad una certa distanza dipende in modo fondamentale dalla massa dei corpi in questione. Per questa ragione sul nostro pianeta si hanno accelerazioni dovute alla gravità diverse da quelle che si hanno sulla luna o su qualsiasi altro corpo celeste avente massa diversa. Sulla superficie terrestre, l’accelerazione di gravità varia di poco, non è però una costante del pianeta, e non è neppure identica all’interno di una stessa area geografica; infatti, si ha una influenza determinante della distribuzione della massa, ossia della densità del pianeta Terra che può variare da luogo a luogo. Nel sottosuolo infatti ci possono essere zone più o meno dense a seconda della costituzione delle rocce, della presenza di cavità, di falde acquifere, di giacimenti minerari o di idrocarburi. Dunque tra due masse M1 ed M2 si esercita una forza di attrazione grazie alla quale, per esempio la Terra e gli altri pianeti sono obbligati a restare nelle loro orbite intorno al Sole anziché fuggire nello spazio. Questa forza gravitazionale (F=GxM1xM2/r2) diminuisce rapidamente al crescere della distanza r tra centri di gravità dei due corpi ed è percepita se almeno una delle masse è molto grande e la distanza è relativamente piccola essendo la costante di gravitazione G molto piccola (G=6,67x10-11 m3s-2 kg-1). Ogni corpo, quindi anche il nostro pianeta, crea intorno a sé un campo gravitazionale direttamente proporzionale alla sua massa ed inversamente proporzionale al quadrato della distanza di un punto dello spazio dal centro di gravità del corpo in questione; questo campo si esprime come H = GxM/r2 ed ha le dimensioni di un'accelerazione. Il segno è assunto convenzionalmente negativo indicando con questo che H è diretta verso il centro della Terra

Uncertainty evaluation of the IMGC-CNR static expansion system

A primary system based on the so-called static expansion of gases has been made available at IMGC-CNR for gauge calibration in the range 0.1 Pa to 1000 Pa. As is known, in such systems the generated pressure is calculated by application of the ideal gas law and is a function of the inlet pressure, the temperatures of the various volumes and their ratios. The uncertainty evaluation of the pressure measured with such system is the main subject of this paper. At present, the system is operated with three volumes (approximate to 0.01 litre, approximate to 0.5 litre and 50 litre) and two expansion ratios (R-4 congruent to 4761 and R-3 congruent to 95) determined by application of the multiple expansion method through pressure measurements performed with the best transfer gauges available at IMGC-CNR. The characteristics of such transfer gauges are discussed with respect to two different conditions of use: that is, for determination of the expansion ratio, R-j, and for measurements of the inlet pressure. The combined expanded uncertainty of the generated pressure (p(xi)) is then given by U(p(xi))/Pa 1.0 x 10(-4) + 1.7 x 10(-3) p(xi)/Pa in the pressure range 0.1 Pa to 10 Pa and U(p(xi))/Pa 1.7 x 10(-2) + 8.2 x 10(-4) p(xi)/Pa in the range 10 Pa to 1000 Pa. Considerations on participation in comparisons are also presented