732 resultados para long-period fiber gratings


Relevância:

100.00% 100.00%

Publicador:

Resumo:

Purpose - This paper aims to demonstrate the need for an improved understanding of the opportunities offered by privacy online. This is contextualized in the case of supermarket purchases of food in particular, often described as an intimate and personal choice. In the case of grocery shopping, the "intimacy" may be at the household level between members or/and between e-grocers' food offerings, and their other "non-food" related services Design/methodology/approach - This paper draws upon social practice theory research, retailing and consumer behaviour in order to develop a conceptual framework for understanding the value of positive privacy. The research uses 39 in-depth interviews of e-grocery shoppers in the area of Portsmouth (UK). Findings - This paper suggests a framework for embedded elements of positive privacy into retailing strategy as a driver for growth in the e-grocery sector. Three meta-themes requiring different approaches to privacy are uncovered. Positive privacy is dynamic and contextual at the consumer/household levels as well as for product/e-grocery brands. Research limitations/implications - This paper advocates the building of long-term sustainable relationship through sharing, offering, and exchange of information rather than pure technological chasing of data. Originality/value - A consumer centred bottom-up approach is employed demonstrating the value of two-way dialogues with consumers on sensitive issues. E-grocery is used as an illustration that involves regular re-purchase of a basket of staple goods over a long period of time where privacy becomes a latent long-term concern. © Emerald Group Publishing Limited.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Molecular transport in phase space is crucial for chemical reactions because it defines how pre-reactive molecular configurations are found during the time evolution of the system. Using Molecular Dynamics (MD) simulated atomistic trajectories we test the assumption of the normal diffusion in the phase space for bulk water at ambient conditions by checking the equivalence of the transport to the random walk model. Contrary to common expectations we have found that some statistical features of the transport in the phase space differ from those of the normal diffusion models. This implies a non-random character of the path search process by the reacting complexes in water solutions. Our further numerical experiments show that a significant long period of non-stationarity in the transition probabilities of the segments of molecular trajectories can account for the observed non-uniform filling of the phase space. Surprisingly, the characteristic periods in the model non-stationarity constitute hundreds of nanoseconds, that is much longer time scales compared to typical lifetime of known liquid water molecular structures (several picoseconds).

Relevância:

100.00% 100.00%

Publicador:

Resumo:

In this paper, we propose a simplified approach to optical signal predistortion based on adaptive pulse shaping through asymmetrical control of a Mach-Zehnder modulator above its switching voltage. The scheme allows natural tailoring of transmitted pulses by optimizing the received pulse. We demonstrate enhancement of the power tolerance in nonrepeated systems and improved OSNR/BER performance and dispersion tolerance in ultra-long-haul fiber systems operating at 10 Gb/s and 20 Gb/s channel rates. The improved performance is demonstrated through simulations and experiment.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

The adaptation of profit sharing creates a fundamental change in employee compensation by making a portion of total compensation directly dependent upon the total profits of the firm and the performance of the employee. The major goal of this study is to test for and measure the impact of the independent variable, a profit sharing plan implemented at Shahvand Industrial Company, upon communication behaviour, communication outcomes, and organisational outcomes as dependent variables. A quasi-experimental non-equivalent control group design with pre and posttest was the research design used to test the effects of profit sharing participation on permanent-part-time operative employees implemented by SIC. Several conclusions were reached as a result of the statistical analysis of the data collected in this study. Overall, few of the hypothesised effects of profit sharing participation appeared to have been realised according to the empirical results of this study. The finding that certain communication behaviours were more favourable for profit sharing participants than for non-participants support the general hypothesis of the integrated profit sharing model. The observed changes in communication behaviours indicate that information sharing and idea generation are important components of the profit sharing process. The results of this study did not reveal any changes in either communication or organisational outcomes. A significant finding of this study is that the implementation of profit sharing plans require a relatively long period of time. Patience is required to achieve high levels of success and management must make long-term commitment to profit sharing. Findings of this study should be interpreted with caution, taking into consideration that most of the previo.us researches on profit sharing have been conducted in Western European or American countries, while the current study was based on data collected from an organisation in a developing country. This implies that the findings reported in this thesis may not be comparable in certain respects to results derived from companies in major industrialised economies.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

The interaction of ionising radiation with polymers is described and the literature relating; to the effects on polypropylene is reviewed. Oxidative and free radical reactions are discussed with particular reference to post-irradiationeffects.Isotactic and atactic polypropylene were δ and electron irradiated to doses of up to 20 megarad. Irradiations weremainly made in air. A series of other polymers were also irradiated in a preliminary survey. Molar mass measurements are used to measure the radiationyield for chain scission G (s). Irradiation at room temperature causes significantly more chain scission than at 195K. Additional chain scission occurs on storage following irradiation at 195 K. Free radical concentrations are determined by electron spin resonance, and the decay rates measured. The radical formed in air is a peroxy radical and in vacuo is a hydrocarbon radical. At77K in vacuo the radical is -CH2 - C* (CH3) - CH2 - but additional radicals are produced on warning to room temperature. The effects of increasing tenparature on radicals formed in air are described. Electron spin resonance studies on atactic polypropylene,and isotactic polypropylene in hydrogen, sulphur dioxide and nitric oxide are reported.. The melting temperatures, spherulite growth rates, and isothermal crystallisation rates of irradiated polypropylene are compared to those of the non-irradiated polymer. Crystallisation is found to proceed with an Avrami integer n = 2. At a given crystallisation temperature, the overall crystallisation rate of irradiated polymer is less than the non-irradiated, but spherulite growth rates are identical. Thermogravimetric analysis is used to assess the thermal stability of irradiated polypropylene in nitrogen, air and oxygen. Hydroperoxide analysis is used to show that several molecules of oxygen are absorbed for each initial radical, and that hydroperoxides continue to be formed for a long period following irradiation. Possible solutions for minimising irradiation and post-irradiation degradation are suggested, together with some problems for further study.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

It is proposed that convection driven dynamos operating in planetary cores could be oscillatory even when the oscillations are not directly noticeable from the outside. Examples of dynamo simulations are pointed out that exhibit oscillations in the structure of the azimuthally averaged toroidal magnetic flux while the mean poloidal field shows only variations in its amplitude. In the case of the geomagnetic field, global excursions may be associated with these oscillations. Long period dynamo simulations indicate that the oscillations may cause reversals once in a while. No special attempt has been made to use most realistic parameter values. Nevertheless some similarities between the simulations and the paleomagnetic record can be pointed out. Crown Copyright © 2008.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Mechanical physiological pulsations are movements of a body surface incited by the movements of muscles in organs inside the body. Here we demonstrate the use of long-period grating sensors in the detection of cardio-vascular pulsations (CVP), in particular apex and carotid pulsations. To calibrate the sensors, we use a mechanical tool designed specifically to measure the sensor response to a localized perturbation at different grating curvatures as working points. From the data we infer the amplitude of the CVP. Together with the electrophysiological signals, the CVP signals obtained from the sensors can provide significant information on heart function which is inaccessible to the electrocardiogram. The low cost and easy handling of the fibre sensors increase their prospects to become the sensors of choice for novel diagnostic devices. © 2013 The Royal Swedish Academy of Sciences.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Background. Schizophrenia affects up to 1% of the population in the UK. People with schizophrenia use the National Health Service frequently and over a long period of time. However, their views on satisfaction with primary care are rarely sought. Objectives. This study aimed to explore the elements of satisfaction with primary care for people with schizophrenia. Method. A primary care-based study was carried out using semi-structured interviews with 45 patients with schizophrenia receiving shared care with the Northern Birmingham Mental Health Trust between 1999 and 2000. Results. Five major themes that affect satisfaction emerged from the data: the exceptional potential of the consultation itself; the importance of aspects of the organization of primary care; the construction of the user in the doctor-patient relationship; the influence of stereotypes on GP behaviour; and the importance of hope for recovery. Conclusion. Satisfaction with primary care is multiply mediated. It is also rarely expected or achieved by this group of patients. There is a significant gap between the rhetoric and the reality of user involvement in primary care consultations. Acknowledging the tensions between societal and GP views of schizophrenia as an incurable life sentence and the importance to patients of hope for recovery is likely to lead to greater satisfaction with primary health care for people with schizophrenia.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

A widely tunable and room-temperature operationable loss filter based on a long-period fibre grating (LPFG) fabricated in a B/Ge codoped fibre is reported. The filter exhibits extremely high temperature sensitivity. A maximum spectral shift of -48.1 nm from 10 to 40°C is achieved, corresponding to a thermal tuning efficiency of 1.6nm/°C. This value is increased by more than one order of magnitude compared with the LPFGs fabricated in standard telecom fibre, and even twice that of a LPFG with sensitivity enhanced by a special polymer.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

We report a novel tunable dispersion compensator (TDC) based on all-fiber distributed Gires-Tournois etaIons (DGTE), which is formed by overlapped chirped fiber gratings. Two DGTEs of opposite dispersion slope work together to generate a tunable periodical dispersion profile. The demonstrated TDCs have the advantages of multichannel operation, extremely low group-delay ripple, low loss, and low cost.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

We propose and demonstrate an optical liquid level sensor based on the surrounding medium refractive index (SRI) sensing using an excessively tilted fibre grating (ETFG). When the ETFG submerged in water, two sets of cladding modes are coupled, corresponding to air- and water-surrounded grating structures, respectively. The coupling strengths of the two sets of cladding modes evolve with the submerging length of the grating, providing a mechanism to measure the liquid level. Comparing with long-period fibre grating based liquid level sensor, the ETFG sensor has a much higher SRI responsivity for liquids with refractive index around 1.33 and a lower thermal cross sensitivity. © 2013 Published by Elsevier B.V. All rights reserved.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Non-invasive ventilation performed through an oronasal mask is a standard in clinical and homecare mechanical ventilation. Besides all its advantages, inevitable leaks through the mask cause errors in the feedback information provided by the airflow sensor and, hence, patient-ventilator asynchrony with multiple negative consequences. Here we investigate a new way to provide a trigger to the ventilator. The method is based on the measurement of rib cage movement at the onset of inspiration and during breathing by fibre-optic sensors. In a series of simultaneous measurements by a long-period fibre grating sensor and pneumotachograph we provide the statistical evidence of the 200 ms lag of the pneumo with respect the fibre-optic signal. The lag is registered consistently across three independent delay metrics. Further, we discuss exceptions from this trend and identify the needed improvements to the proposed fibre-sensing scheme.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Tanulmányunkban egy olyan rendszerrel foglalkozunk, amely köztes helyet foglal el a demokrácia és az autokrácia között, mindkettő jegyeit magán viseli, és amelyet ezért áldemokráciának nevezünk. A rendszer működési sajátosságait a járadékok szemszögéből vizsgáljuk, és arra keressük a választ, hogy demokratikus országokban hogyan képes egy párt tartósan domináns pozícióban maradni. Modellünk segítségével összekapcsoljuk a járadékteremtést a szavazatok maximalizálásának céljával, és bemutatjuk, miért jelenthet racionális döntést a hatalmon lévők számára a rövid távú optimumon túlmutató járadékteremtés is. A modell rávilágít arra, hogy a többletjáradékok segítségével a kormányzat - klientúrája megerősítése, a demokratikus rendszer határainak feszegetése, valamint az ellenzék visszaszorítása révén - hosszú távú előnyökre tehet szert, áldemokráciát hozva létre. Történelmi példák jól mutatják, hogy a rendszer bukását végül általában a gyengébb gazdasági teljesítmény és a korrupció széles körűvé válása kényszeríti ki. _____ The paper focuses on a specific political system lying between democracy and autocracy, which has similarities to both. Called here a pseudo-democracy, it is examined from the point of view of rents. The paper enquires how a democracy can allow a single party to dominate the political landscape for a long period. The author constructs a model to link rent creation to vote maximization, arguing that it can be rational for incumbents to increase rents beyond the short-term optimum. The model also reveals that surplus rents may offer long-term gains to an elite by strengthening its clientčle, challenging the systemic political framework and holding back the opposition. Historical examples show that the end-result of a pseudo-democratic system will usually be to weaken economic performance and increase corruption.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

This dissertation was an analysis of the root and proximate causes of the September 2002 civil war in Côte d’Ivoire. The central question of this study was: Why did Côte d’Ivoire, which was relatively stable under President Houphouët-Boigny, suddenly begin to experience political violence in the 1990s and an explosion in 2002? Côte d’Ivoire was an interesting case because it was stable for a long period of time, apparently making it an infertile ground for conflict. It was also interesting for comparative purposes because of the fact that several states in West Africa (for instance, Benin, Togo, and Ghana) have experienced military coups but not have civil wars. Finally, this case was an opportunity to revisit the debate on the causes of civil wars in the African context. Chapter one has outlined the entire dissertation project and contextualized the analysis that follows in the subsequent chapters. Chapter two has reviewed the literature on civil wars in general, identified the different types of civil wars, and the type the Ivoiran war is. Chapter three has examined the domestic and international political economy as a source of the civil violence in Côte d’Ivoire. Chapter four has examined the role of ethnicity and region as identities of the war, while chapter five has analyzed the role of the foreign relations in the civil war, as well as the regional political context. Chapter six has distinguished between the root and proximate causes of the Ivoirian civil war, made judgments about the relative weight of the various causes, and the extent to which the weight of the causes can be measured. The study found that the “Ivoirité” was the most important trigger of the civil war in Côte d’Ivoire. The overall conclusion of my dissertation was that the September 2002 crisis in that country was a political crisis which occured in the context of a political reform. It first started with succession problems in 1993 followed by the controversial elections in 1995 and 2000. Later, this electoral politics spread beyond electoral issues, namely citizenship matters.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

A LLE-GC-MS method was developed to detect PPCPs in surface water samples from Big Cypress National Park, Everglades National Park and Biscayne National Park in South Florida. The most frequently found PPCPs were caffeine, DEET and triclosan with detected maximum concentration of 169 ng/L, 27.9 ng/L and 10.9 ng/L, respectively. The detection frequencies of hormones were less than PPCPs. Detected maximal concentrations of estrone, 17β-estradiol, coprostan-3-ol, coprostane and coprostan-3-one were 5.98 ng/L, 3.34 ng/L, 16.5 ng/L, 13.5 ng/L and 6.79 ng/L, respectively. An ASE-SPE-GC-MS method was developed and applied to the analysis of the sediment and soil area where reclaimed water was used for irrigation. Most analytes were below detection limits, even though some of analytes were detected in the reclaimed water at relatively high concentrations corroborating the fact that PPCPs do not significantly partition to mineral phases. An online SPE-HPLC-APPI-MS/MS method and an online SPE-HPLC-HESI-MS/MS method were developed to analyze reclaimed water and drinking water samples. In the reclaimed water study, reclaimed water samples were collected from the sprinkler for a year-long period at Florida International University Biscayne Bay Campus, where reclaimed water was reused for irrigation. Analysis results showed that several analytes were continuously detected in all reclaimed water samples. Coprostanol, bisphenol A and DEET's maximum concentration exceeded 10 μg/L (ppb). The four most frequently detected compounds were diphenhydramine (100%), DEET (98%), atenolol (98%) and carbamazepine (96%). In the study of drinking water, 54 tap water samples were collected from the Miami-Dade area. The maximum concentrations of salicylic acid, ibuprofen and DEET were 521 ng/L, 301 ng/L and 290 ng/L, respectively. The three most frequently detected compounds were DEET (93%), carbamazepine (43%) and salicylic acid (37%), respectively. Because the source of drinking water in Miami-Dade County is the relatively pristine Biscayne aquifer, these findings suggest the presence of wastewater intrusions into the delivery system or the onset of direct influence of surface waters into the shallow aquifer.