161 research outputs found

    Motivation of Generation Y employees in resort hotels during the summer season in Greece

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    In the near future the majority of the workforce globally will be covered by Generation Y employees. The unique characteristics of this generation’s working values and the differences that appear compared to other generations, have led researchers to investigate this generational cohort for many purposes. This thesis examines the ways in which Generation Y employees in resort hotels are motivated in Greece. The research aimed at providing the commissioning company, Lindian Village, with valuable insights that may have allowed it to use this information as guidance in the pursuance of improving the practices that lead in increased motivation. With regard to the aim of the thesis and the importance it may hold as guidance for the commissioner, a theoretical framework was put together to understand the three subjects, which composed are shaping the research question. Furthermore, the design and execution of a qualitative research through semi-structured interviews added a valuable amount of personal insights that justify the theory analysed in the thesis and the aim of the research. The key findings of the study showed that the employees’ motivation is increased by several intrinsic and extrinsic factors such as the personal advancement, the recognition of one’s effort, the competitive salary and the status derived from the position

    Χωροχρονική ανάλυση εμπορικών δραστηριοτήτων σε περιβάλλον GIS: η περίπτωση του Δήμου Πατρέων

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    Εθνικό Μετσόβιο Πολυτεχνείο--Μεταπτυχιακή Εργασία. Διεπιστημονικό-Διατμηματικό Πρόγραμμα Μεταπτυχιακών Σπουδών (Δ.Π.Μ.Σ.) “Γεωπληροφορική

    17O solid state NMR study of ceria systems

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    Ceria is a highly commercial, valuable material. Its diverse set of real-world applications demonstrates its far-reaching influence on modern society. Indeed, one only has to consider its extensive employment as an essential component of automotive, three-way catalysis (TWC) for reducing pollutants in vehicular exhaust gases; a technology that is used on a daily basis by millions of people, to appreciate its importance. Its popularity is partially due to its extraordinary oxygen storage capacity, i.e. its ability to release and store oxygen through redox reactions mediated by the two oxidation states of cerium (Ce3+/Ce4+). This unique ability can be heavily influenced by ceria’s particle size and shape, dopant concentration and surface chemistry, and is still a very active area of research today. Whilst there have been over 26,000 scientific publications on ceria since the 1950s, and although the bulk-ceria oxygen chemical shift (877 ppm) was first observed with 17O solid-state NMR in 1989, it is only within the past decade that solid-state NMR has been employed as a probe for ceria’s structure-function relationships. This study presents an extensive 17O solid-state NMR investigation into various ceria systems, in conjunction with complementary Raman spectroscopy (for which the literature is abundant). An alternative spectral assignment for the 17O NMR spectrum of nanoceria based on experimental deductions and DFT quantum mechanical calculations is proposed. The current working assignment for nanoceria is based on the work of Wang et al., where DFT calculations of a core-shell model are used to deconvolute the NMR data. In contrast to this model, it is suggested that the most upfield peak at δCG = 822 ppm (that is actually part of a multicomponent region centred at ~830 ppm), corresponds to oxygen species displaced from their standard sublattice positions, to occupy a Frenkel type defect site. The resonance regions observed at ~830 and 920 ppm are proposed to be bulk oxygen environments feeling the effects of the Frenkel defect and concomitant oxygen vacancy. For reduced ceria systems, a broad component is detected that spans > 1000 ppm, and is assigned to oxygen directly bonded to Ce3+, in agreement with the current working model. Finally, it is observed that the most deshielded peak at ~1030 ppm is multi-component and (one of these components) possesses an extensive spinning sideband manifold in comparison to the other 17O resonances. Variable temperature investigations show a small inverse temperature dependence of the peak positions, suggesting weak pseudocontact paramagnetic shifts are influencing the spectrum. In light of this, the peak at ~1030 ppm is assigned to oxygen in closer proximity to (but not directly bonded) to Ce3+, as is reported by current 27Al solid-state NMR studies of Ce3+ doped systems and as is reflected by the extensive sideband manifold. The novel 17O preparation treatments implemented in this work were engineered to probe oxygen environments near defects. Ceria’s defects are manipulated by exposure to certain temperature/atmospheric conditions, and when these replicate those of possible catalyst operating temperatures with 17O enriched gas, 17O is able to probe the distribution of oxygen in distinct sites that are important to the OSC process. A prereduction of ceria was therefore implemented, following 17O2 reoxidation to target these sites. This process was also able to identify a surface reorganization mechanism in which a low reoxidation temperature/ pressure of 17O2 is insufficient to reverse the onset of bulk oxygen diffusion induced by the reduction, an effect which is seen to be enhanced with the loading of Pd. Furthermore, the storage of these treated systems dictates the evolution of the 17O species, with an almost closed-system (to air) detecting the pathway of reoxidised oxygen species to more stable sites over time. Ceria zirconia systems are also investigated in this work. The 17O solid-state NMR spectra show an even greater sensitivity to the 17O2 enrichment conditions. The pre-reduction of the systems induces a greater oxygen removal compared to pure ceria, and thus an increase in Ce3+ paramagnetic centres, i.e. the broad component (> 1000 ppm) characterising the oxygen-Ce3+ bond reveals a greater relative intensity. The complication of increasing Ce3+ paramagnetic centres near the 17O adsorption sites is evidenced by the significant loss in 17O spectral resolution. These effects are exacerbated when ceria zirconia is supported with Pd, known to (stably) reduce the state of the system even further. A straight exchange of the 17O isotope in ceria zirconia helps to inhibit these effects, allowing observation of (1) the chemical shift of the bulk-ceria oxygen move to a more shielded position compared to the pure ceria material at 877 ppm (caused by the inherent contraction of the ceria zirconia lattice), and (2) a broad resonance at ~730 ppm, attributed to oxygen species bridging cerium and zirconium

    What Else Would I Like? A User Simulator using Alternatives for Improved Evaluation of Fashion Conversational Recommendation Systems

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    In Conversational Recommendation Systems (CRS), a user can provide feedback on recommended items at each interaction turn, leading the CRS towards more desirable recommendations. Currently, different types of CRS offer various possibilities for feedback, i.e., natural language feedback, or answering clarifying questions. In most cases, a user simulator is employed for training as well as evaluating the CRS. Such user simulators typically critique the current retrieved items based on knowledge of a single target item. Still, evaluating systems in offline settings with simulators suffers from problems, such as focusing entirely on a single target item (not addressing the exploratory nature of a recommender system), and exhibiting extreme patience (consistent feedback over a large number of turns). To overcome these limitations, we obtain extra judgements for a selection of alternative items in common CRS datasets, namely Shoes and Fashion IQ Dresses. Going further, we propose improved user simulators that allow simulated users not only to express their preferences about alternative items to their original target, but also to change their mind and level of patience. In our experiments using the relative image captioning CRS setting and different CRS models, we find that using the knowledge of alternatives by the simulator can have a considerable impact on the evaluation of existing CRS models, specifically that the existing single-target evaluation underestimates their effectiveness, and when simulated users are allowed to instead consider alternatives, the system can rapidly respond to more quickly satisfy the user

    Seed germination, micropropagation from adult and juvenile origin explants and address of hyperhydricity of the Cretan endemic herb Calamintha cretica

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    The optimum range of temperature for germination (96-100%) of Calamintha cretica, an herb with potential pharmaceutical and horticultural uses, was 15 to 20 °C, with 10 and 30 °C cardinal temperatures. Storage up to one year did not affect germination. The effect of zeatin (ZEA), 6-benzyladenine (BA), kinetin, and 6-γ-γ-(dimethylallylamino)-purine added in MS medium at concentrations from 0.0 to 8.0 mg L-1 was tested for shoot proliferation of both adult- and seedling-origin nodal explants at first- and sub-culture. Both explant types responded similarly during in vitro culture. At cytokinin concentrations up to 1 mg L-1 explant response was high (over 85%) but shoot number per explant was low (1.2-2.2). Increasing cytokinin from 2.0 to 8.0 mg L-1 resulted to an analogous decrease of explant response and shoot length, and an increase of shoot number, particularly when ZEA or BA was used (5.0-6.6 shoots per explant, 0.5-1.0 cm long) with simultaneous though increase of hyperhydricity (up to 50%). The addition of 0.1 mg L-1 naphthaleneacetic acid into the 8.0 mg L-1 BA medium almost eliminated hyperhydricity and increased explant response, while the increase of agar concentration from 8.0 to 12.0 g L-1 eliminated hyperhidricity and induced the highest shoot proliferation (93-95% explant response, 11.2-12.3 shoots per explant, 0.8-1.0 cm long). Microshoots and microshoot clusters rooted (88-96%) on half-strength MS medium either hormone free or supplemented with 1 to 4 mg L-1 indole-3-butyric acid. Plantlets survived at 80% to 100% after ex vitro acclimatization in peat: perlite 1:1 (v/v)

    Hemolymphangioma of the lower extremities in children: two case reports

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    Abstract Background and purpose Hemo-lymphangiomas are rare benign tumors that arise from congenital malformation of the vascular system. They are usually diagnosed at birth or early in childhood. The management of hemo-lymphangiomas in children remains challenging because complete resection is often difficult to be achieved and recurrences are common. Methods We present the case of two children with a mass on their left tibia. Imaging modalities, plain radiograph, Ultrasonography and Magnetic Resonance were used to investigate the nature of the mass, the anatomical relationship to the neighboring tissues and help planning the surgical resection. The dominant diagnosis was hemo-lymphangioma. Both lesions increased in size in a short period of follow-up thus we decided to proceed to surgical excision. The diagnosis of hemo-lymphangioma was confirmed by histological examination of the surgical specimen. Post-operatively, seroma was formed to the first patient, managed by placing a drainage and immobilizing the limb on a splint. The second patient experienced no complications post-operatively. After 12 months of follow-up both patients had no complications or recurrence. Conclusions Very few cases of hemo-lymphangiomas of the extremities have been reported in the literature. Those tumors can grow slowly and remain asymptomatic for a long period of time or may become aggressive and enlarge rapidly, without invasive ability though. Radical resection is the choice of treatment offering the lowest recurrence rates. Other therapeutic methods are: aspiration and drainage, cryotherapy, injection of sclerotic agents and radiotherapy; although none of those offers better results that the surgical excision.</p

    A multi-factorial genetic model for prognostic assessment of high risk melanoma patients receiving adjuvant interferon

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    Purpose: IFNa was the first cytokine to demonstrate anti-tumor activity in advanced melanoma. Despite the ability of high-dose IFNa reducing relapse and mortality by up to 33%, large majority of patients experience side effects and toxicity which outweigh the benefits. The current study attempts to identify genetic markers likely to be associated with benefit from IFN-a2b treatment and predictive for survival. Experimental design: We tested the association of variants in FOXP3 microsatellites, CTLA4 SNPs and HLA genotype in 284 melanoma patients and their association with prognosis and survival of melanoma patients who received IFNa adjuvant therapy. Results: Univariate survival analysis suggested that patients bearing either the DRB1*15 or HLA-Cw7 allele suffered worse OS while patients bearing either HLA-Cw6 or HLA-B44 enjoyed better OS. DRB1*15 positive patients suffered also worse RFS and conversely HLA-Cw6 positive patients had better RFS. Multivariate analysis revealed that a five-marker genotyping signature was prognostic of OS independent of disease stage. In the multivariate Cox regression model, HLA-B38 (p = 0.021), HLA-C15 (p = 0.025), HLA-C3 (p = 0.014), DRB1*15 (p = 0.005) and CT60*G/G (0.081) were significantly associated with OS with risk ratio of 0.097 (95% CI, 0.013-0.709), 0.387 (95% CI, 0.169-0.889), 0.449 (95% CI, 0.237-0.851), 1.948 (95% CI, 1.221-3.109) and 1.484 (95% IC, 0.953-2.312) respectively. Conclusion: These results suggest that gene polymorphisms relevant to a biological occurrence are more likely to be informative when studied in concert to address potential redundant or conflicting functions that may limit each gene individual contribution. The five markers identified here exemplify this concept though prospective validation in independent cohorts is needed

    The Effect of Virtual Reality Intervention Programs on the Functionality of Children and Adolescents with Cerebral Palsy. A Systematic Review

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    Background: Cerebral Palsy (CP) is a neurological disorder of movement and posture. Recent studies have shown that Virtual Reality (VR) is a useful and low-cost tool used in treating children and adolescents with cerebral palsy. Nevertheless, there is no substantial evidence supporting that VR therapy can help CP patients, not only as the primary treatment, but as a supplement. Objectives: The present systematic review aimed to investigate the effectiveness of VR intervention programs on the functional capacity of children and adolescents with CP, according to the International Classification of Functioning, Disability and Health (ICF). Methods: A systematic online search was conducted in PubMed, Scopus, and PEDro databases, as well as in the Google Scholar search engine, from inception till September 2022. The methodological quality of included studies was rated with the PEDro scale. Results: Twenty-two randomized-controlled trials were eligible for inclusion. The results indicated that there was a significant improvement after the implementation, of interventional VR programs, in balance and visual perception, while the results were controversial for muscle strength, coordination, gross motor function, gait, upper limb function, independence in activities of Daily Life Activities and participation. Conclusion: Significant balance and visual perception improvements may result from VR programs applied in children and adolescents with CP. Important factors that may influence the results are the functional level of the participants, the sample size, the context in which the therapeutic intervention is carried out (rehabilitation center, home), and the conventional treatments that the VR intervention programs are compared against
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