Economic feasibility of small wind turbines for domestic consumers in Egypt based on the new feed-in tariff

This paper provides an overview of the wind power potential at different regions in Egypt, along the Mediterranean and Red Sea, and the Western desert. A further technical and economic assessment is conducted for the electricity generation with 8 different small wind turbines at 17 locations. The annual electricity generation from selected wind turbines is evaluated. The obtained data are presented and discussed investigating the net present value and the payback period analyzing the profitability of selected wind turbines. The dependence of the turbine profitability from the feed-in tariff is specifically addressed

An Efficient Source of Single Photons: A Single Quantum Dot in a Micropost Microcavity

We have demonstrated efficient production of triggered single photons by coupling a single semiconductor quantum dot to a three-dimensionally confined optical mode in a micropost microcavity. The efficiency of emitting single photons into a single-mode travelling wave is approximately 38%, which is nearly two orders of magnitude higher than for a quantum dot in bulk semiconductor material. At the same time, the probability of having more than one photon in a given pulse is reduced by a factor of seven as compared to light with Poissonian photon statistics

Solid-liquid equilibria for the dimethyl ether plus carbon dioxide binary system

A recently built experimental setup was employed for the estimation of the solid-liquid equilibria of alternative refrigerants systems. The behavior of dimethyl ether (DME) + carbon dioxide was measured down to temperatures of 131.6 K. To confirm the reliability of the apparatus, the triple point of the DME was measured. The triple point data measured revealed a good consistency with the literature. The results obtained for the mixtures were corrected by the Rossini method and interpreted by means of the Schröder equation. © 2010 Akadémiai Kiadó, Budapest, Hungary

Experimental measurement technique for the assessment of the fuel crossover diffusion coefficient in the membrane electrode assembly of a direct methanol fuel cell

Since the cross-over still seems to be the main issue of the direct methanol fuel cells, an experimental evaluation of the diffusive cross-over is performed. Even if the relationship of the rate through the membrane is the sum of the three terms of diffusive, osmotic and drag, the diffusive component is also present at open circuit lowering the Open Circuit Voltage of the single cell up to 50 % with respect to the Nernst potential. The goal of the research is to develop a direct measurement technique of the crossover that can provide the effective values of the parameters that characterize the membrane electrode assembly. The experimental set up consists in the pressure, flow and temperature control and acquisition using Labview. A sensitive analysis for three values of temperatures at 60°C, 65°C and 70°C is performed for first. Then, a small overpressure was generated in the cathode side by a valve located at the cathode outlet. A set of pressure were analysed for 0, 30 and 90 mbar of overpressure at the cathode. The tested fuel cell has a commercial Nafion 117 membrane and carbon paper gas diffusion layers 700 cm2 large. Preliminary results show that the differential concentration term seems to be significantly larger than the osmotic term. The diffusion coefficients are useful for fuel cell modelling and for the calibration of the operating conditions in the sensor less DMFC systems

Enhanced single-photon emission from a quantum dot in a micropost microcavity

We demonstrate a single-photon source based on a quantum dot in a micropost microcavity that exhibits a large Purcell factor together with a small multi-photon probability. For a quantum dot on resonance with the cavity, the spontaneous emission rate is increased by a factor of five, while the probability to emit two or more photons in the same pulse is reduced to 2% compared to a Poisson-distributed source of the same intensity. In addition to the small multi-photon probability, such a strong Purcell effect is important in a single-photon source for improving the photon outcoupling efficiency and the single-photon generation rate, and for bringing the emitted photon pulses closer to the Fourier transform limit.Comment: 4 pages, 3 figure

"VALUTAZIONE DELLO STATO VITAMINICO E DEI FATTORI DI RISCHIO ASSOCIATI A IPOVITAMINOSI D IN UNA POPOLAZIONE MULTIETNICA DI MADRI E LORO NEONATI"

Obiettivo Determinare la prevalenza di ipovitaminosi D in donne in gravidanza e nei loro neonati e esaminare i fattori associati alla carenza di vitamina D. Metodi - Somministrazione di un questionario a donne sane in gravidanza a termine per rilevare dati socio-demografici, abitudini culturali e alimentari, fototipo cutaneo. - Assegnazione coppia madre-bambino a due gruppi: un gruppo a rischio (gruppo di studio) di donne in gravidanza con la pelle nera o che non espongono la loro pelle alla luce solare (n = 93) e un gruppo di controllo di donne in gravidanza senza fattori di rischio noti (n = 92) - Determinazione di calcio, fosforo, fosfatasi alcalina, fosfatasi alcalina ossea, vitamina D e livelli di ormone paratiroideo su campione di sangue venoso sangue di cordone ombelicale e materno. Risultati Livelli di vitamina D erano significativamente più bassi nelle donne del gruppo di studio rispetto al gruppo di controllo: 33,0 ng / ml vs 58,9 ng / ml (p <0,001). Il 29% delle donne in gravidanza a rischio aveva valori <20ng/ml, il 25% aveva un valore di 20-30ng/ml e solo il 46% aveva livelli sopra 30ng/ml. I livelli di PTH erano nettamente superiore nel gruppo di rischio rispetto al gruppo di controllo: 48,4 vs 33,0 (p <0.001). La concentrazione di 25OH-VitD3 era significativamente più bassa tra i bambini nel gruppo di studio rispetto al gruppo di controllo: 29.0 ng / ml vs 44.0 ng / ml (p <0.001). 46% dei bambini del gruppo a rischio aveva valori inferiori a 20ng/ml e solo il 38% aveva valori di protezione. 20 dei 27 neonati di madri con ipovitaminosi D del gruppo a rischio presentavano valori di vitamina D <20ng/ml, dimostrando una forte correlazione tra i livelli materni di VITD e quelli trovati nel sangue del cordone ombelicale. Conclusioni I nostri dati confermano che le donne con la pelle scura e di quelli che non si espongono al sole hanno livelli di vitamina D inferiori e loro bambini sono ad alto rischio di ipovitaminosi D. Una supplementazione con adeguate quantità di vitamina D durante la gravidanza è necessaria per prevenire la carenza di vitamina D neonatale. Secondo le linee guida di Endocrine Society, il fabbisogno consigliato di vitamina D per le donne in gravidanza è di 1400 UI al giorno. Allo stesso tempo è importante sottolineare l'utilità della somministrazione di vitamina D per tutti i bambini fin dai primi giorni di vita. L'apporto minimo consigliato è di 400 UI al giorno per il primo anno

Circadian rhythms and sex differences set endocannabinoids to influence memory under stress

A large amount of evidence indicates that stress exposure triggers the brain processing through different specific pathways that converge in both norepinephrine- and glucocorticoids-dependent regulation of memory processes by influencing central noradrenergic mechanisms (de Quervain et al., 1998; McGaugh and Roozendaal, 2002). The amygdala has long been known to be the hub of fear memory, which is usually remembered over time (Fanselow and LeDoux, 1999; Roozendaal et al., 2009). However, when an aversive stimulus occurs, it might happen that the accuracy of such emotional memory could be distorted progressively, leading to memory generalization (Asok et al., 2019). Drugs of abuse were identified to alter the experience of reality, thus affecting memory processes (Goodman and Packard, 2016). Chapter 1 explores more in deep the role of the psychostimulants amphetamine and MDPV in the modulation of memory strength and accuracy in a previously validated model exploiting the inhibitory avoidance discrimination task, in order to assess fear memory generalization for a novel/safe, yet not identical, context that was not used to induce shocks (Atucha and Roozendaal, 2015). Previous studies indicated that both amphetamine and MDPV, through different mechanisms of action, increase brain monoamines release, particularly norepinephrine and dopamine, two neurotransmitters extensively involved in the modulation of memory (LaLumiere et al., 2005; McGaugh and Roozendaal, 2009). Therefore, Chapter 1 investigates the involvement of the noradrenergic and dopaminergic systems in mediating the amphetamine effects on memory strength and both amphetamine and MDPV effects on fear memory generalization. Extensive evidence demonstrates that norepinephrine is crucially involved in the regulation of long-term memory consolidation for emotionally arousing experiences (Ferry et al., 1999; McGaugh and Roozendaal, 2002; Roozendaal et al., 2008; Lalumiere et al., 2017; Chen et al., 2018). It is widely recognized that amphetamine enhances the consolidation of memory processing in both humans and rodents (Soetens et al., 1993; Sanday et al., 2013). Chapter 2 evaluates the influence of different intensities of stress on the amphetamine modulation of long-term memory consolidation, further characterizing the involvement of any stress-induced activation of the peripheral adrenergic response in such process. The endocannabinoid system plays a key role in the control of emotional responses to environmental challenges (Morena and Campolongo, 2014). CB1 receptors are abundantly expressed within corticolimbic regions, including the basolateral complex of the amygdala (BLA), hippocampus and mPFC (Hill et al., 2011). Glucocorticoids are stress response mediators which interact with the endocannabinoid system in the regulation of memory function (Campolongo et al., 2009; Hill et al., 2010a; Atsak et al., 2012a; Morena et al., 2016; Balsevich et al., 2017), with an emotional buffer outcome in such interaction (Morena and Campolongo, 2014). Their synthesis is characterized by a circadian release pattern, with peak levels linked to the start of the activity phase and diurnal regulation under control of the circadian clock (Dickmeis, 2009). Literature evidence indicated that the endocannabinoid signaling exhibits a circadian rhythm with variations reported in CB1 receptor expression (Rueda- Orozco et al., 2008), endocannabinoids tissue contents and in the enzymes controlling their synthesis and degradation (Valenti et al., 2004). Chapter 3 investigates how different stress intensities, soon after encoding, influence rat short-term memory in an object recognition task, whether the effects depend on circadian rhythm and if exogenous augmentation of AEA levels restores any memory impairment provoked by stress exposure. Exposure to stress alters both hippocampal anatomy and functionality (McEwen, 1999), with negative consequences on memory processes (de Kloet et al., 2018). Indeed, the hippocampus represents a key forebrain structure highly associated with emotional and recognition memory processes (Broadbent et al., 2010). According to the timing of stress exposure, stress-mediated secretion of glucocorticoids alters hippocampal functions and plasticity (Kim et al., 2015), thus affecting hippocampal-dependent memories in rodents and humans (Donley et al., 2005). Furthermore, previous findings from our laboratory have demonstrated the involvement of the 2-AG signaling in counteracting the stress-mediated impairments on memory function (Morena et al., 2014, 2015; Ratano et al., 2018). By adding on Chapter 3 findings, Chapter 4 highlights that stress impairing effects on short-term recognition memory depend on time-of-day in a stress intensity-dependent fashion and examines if different stress intensities affect the hippocampal endocannabinoid system components, whether the effects are time-of- day-dependent, and if boosting 2-AG signaling ameliorates memory performance. Excessive fear and anxiety are hallmarks of a variety of disabling psychiatric disorders (Myers and Davis, 2007). The neurocircuitry of fear memory involves the BLA as the key region modulating the acquisition, retrieval and extinction of fear response (Johansen et al., 2011; Adolphs, 2013; Herry and Johansen, 2014; Zelikowsky et al., 2014), by receiving inputs from somatosensory cortex, thalamus, and hippocampus that encodes contextual information and compares current contextual cues to previously encoded memories (Maren and Quirk, 2004). Chapter 5 evaluates whether the endocannabinoids AEA and 2-AG, in the BLA or the CA1 region of the dorsal hippocampus, differentially regulate fear memory retrieval depending on the environment-associated emotional arousal, if these outcomes are mediated by indirect activation of CB1 and/or CB2 receptors, and whether the BLA-dorsal CA1 interplay plays any role in such effects. Women are twice as likely as men to develop PTSD making the search for biological mechanisms underlying these gender disparities especially crucial (Breslau, 2009). One striking feature of PTSD is the alteration in the ability to extinguish fear responses to trauma-associated cues (Yehuda et al., 2015). In male rodents, the endocannabinoid system can modulate fear extinction and has been suggested as a therapeutic target for PTSD (Morena et al., 2018; Segev et al., 2018). Chapter 6 investigates whether exogenous augmentation of the endocannabinoids AEA and 2-AG in male and female rats affect fear expression and extinction, which is the role of CB1 and transient potential receptor of vanilloid type-1 channel (TRPV1) receptors in such mediation, and how the endocannabinoid machinery within the amygdala, PFC and periaqueductal grey (PAG) is influenced post-extinction. Chapter 7 provides a review of the existing literature regarding the effects of time-of- day on memory function, shedding light on the underlying mechanisms of contrasting results by portraying how stress-dependent modulation of memory is influenced by circadian rhythms. Chapter 7 also focuses on the interaction between the endocannabinoid system and the level of stress associated to the experimental context / previous aversive experiences and capitalizes on our recent findings that a manipulation of the endocannabinoid system might be capable to effectively modulate the circadian- dependent effects of stress on memory and to prevent its detrimental effects on memory function

Triggered single photons from a quantum dot

We demonstrate a new method for generating triggered single photons. After a laser pulse generates excitons inside of a single quantum dot, electrostatic interactions between them and the resulting spectral shifts allow a single emitted photon to be isolated. Autocorrelation measurements show a reduction of the two-photon probability to 0.12 times the value for Poisson light. Strong anti-bunching persists when the emission is saturated. The emitted photons are also polarized.Comment: 4 pages, 4 figures, RevTex, to be published in PR