963 resultados para Preservation of Supermodularity
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This dissertation mainly focuses on coordinated pricing and inventory management problems, where the related background is provided in Chapter 1. Several periodic-review models are then discussed in Chapters 2,3,4 and 5, respectively. Chapter 2 analyzes a deterministic single-product model, where a price adjustment cost incurs if the current selling price is changed from the previous period. We develop exact algorithms for the problem under different conditions and find out that computation complexity varies significantly associated with the cost structure. %Moreover, our numerical study indicates that dynamic pricing strategies may outperform static pricing strategies even when price adjustment cost accounts for a significant portion of the total profit. Chapter 3 develops a single-product model in which demand of a period depends not only on the current selling price but also on past prices through the so-called reference price. Strongly polynomial time algorithms are designed for the case without no fixed ordering cost, and a heuristic is proposed for the general case together with an error bound estimation. Moreover, our illustrates through numerical studies that incorporating reference price effect into coordinated pricing and inventory models can have a significant impact on firms' profits. Chapter 4 discusses the stochastic version of the model in Chapter 3 when customers are loss averse. It extends the associated results developed in literature and proves that the reference price dependent base-stock policy is proved to be optimal under a certain conditions. Instead of dealing with specific problems, Chapter 5 establishes the preservation of supermodularity in a class of optimization problems. This property and its extensions include several existing results in the literature as special cases, and provide powerful tools as we illustrate their applications to several operations problems: the stochastic two-product model with cross-price effects, the two-stage inventory control model, and the self-financing model.
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Long-term preservation of bioreporter bacteria is essential for the functioning of cell-based detection devices, particularly when field application, e.g., in developing countries, is intended. We varied the culture conditions (i.e., the NaCl content of the medium), storage protection media, and preservation methods (vacuum drying vs. encapsulation gels remaining hydrated) in order to achieve optimal preservation of the activity of As (III) bioreporter bacteria during up to 12 weeks of storage at 4 degrees C. The presence of 2% sodium chloride during the cultivation improved the response intensity of some bioreporters upon reconstitution, particularly of those that had been dried and stored in the presence of sucrose or trehalose and 10% gelatin. The most satisfying, stable response to arsenite after 12 weeks storage was obtained with cells that had been dried in the presence of 34% trehalose and 1.5% polyvinylpyrrolidone. Amendments of peptone, meat extract, sodium ascorbate, and sodium glutamate preserved the bioreporter activity only for the first 2 weeks, but not during long-term storage. Only short-term stability was also achieved when bioreporter bacteria were encapsulated in gels remaining hydrated during storage.
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Mineralised organic remains (including apple pips and cereal grains) collected during the ongoing excavations of Insula IX at the Roman town of Silchester, Hampshire have been analysed by a combination of SEM-EDX, powder XRD and IR spectroscopy. The experiments included mapping experiments using spatially resolved versions of each technique. IR and powder XRD mapping have been carried out utilising the synchrotron source at The Daresbury Laboratory oil stations 11.1 and 9.6. It is concluded that these samples are preserved by rapid mineralisation in the carbonate-substituted calcium phosphate mineral, dahllite. The rapid mineralisation leads to excellent preservation of the samples and a small crystal size. The value of IR spectroscopy in studying materials like this where the crystal size is small is demonstrated. A comparison is made between the excellent preservation seen in this context and the much poorer preservation of mineralised remains seen in Context 5276 or Cesspit 5251. Comments on the possible mechanism of mineralisation of these samples are made. (C) 2008 Elsevier B.V.. All rights reserved.
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Mineralised organic remains (including apple pips and cereal grains) collected during the ongoing excavations of Insula IX at the Roman town of Silchester, Hampshire have been analysed by a combination of SEM-EDX, powder XRD and IR spectroscopy. The experiments included mapping experiments using spatially resolved versions of each technique. IR and powder XRD mapping have been carried out utilising the synchrotron source at The Daresbury Laboratory oil stations 11.1 and 9.6. It is concluded that these samples are preserved by rapid mineralisation in the carbonate-substituted calcium phosphate mineral, dahllite. The rapid mineralisation leads to excellent preservation of the samples and a small crystal size. The value of IR spectroscopy in studying materials like this where the crystal size is small is demonstrated. A comparison is made between the excellent preservation seen in this context and the much poorer preservation of mineralised remains seen in Context 5276 or Cesspit 5251. Comments on the possible mechanism of mineralisation of these samples are made. (C) 2008 Elsevier B.V.. All rights reserved.
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Most museums, libraries, and archives throughout the world have to deal with paper damaged by iron gall ink. For more than a decade international research has been devoted to the topic in an attempt to provide practical treatments for objects and formulate guidelines for the preservation of iron gall ink collections. A working group of conservators in South and Central America and the Caribbean have developed a program to disseminate research findings, collect data about the condition of iron gall ink collections in their countries and identify imminent training needs. The goal of this project is to combine the latest research with existing and acceptable conservation practices and share information about risk management, proper housing, examination and treatment of iron gall ink inscribed artefacts-at risk. Communications among colleagues were established to learn more about the current resources available in collections from various countries.
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OBJECTIVES Pain control after thoracotomy is an important issue that affects the outcome in thoracic surgery. Intercostal nerve preservation (ICNP) has increased interest in the outcomes of conventional thoracotomy. The current study critically evaluates the role of preservation of the intercostal nerve in early and late pain control and its benefit in patients undergoing thoracotomy. METHODS Data obtained prospectively between January 2006 and December 2010 by a study colleague at our division of General Thoracic Surgery were retrospectively analysed. There were 491 patients who underwent thoracotomy. Eighty-one patients were excluded from the study due to incompatible data. Patients were divided into two groups according to the intercostal nerve state: Group I consisted of patients with ICNP and Group II consisted of patients with intercostal nerve sacrifice. RESULTS Group I consisted of 288 patients [206 male (71%), P < 0.001, mean age 66 years]. Group II consisted of 122 patients [79 male (64%), P = 0.001, mean age 66 years]. There was less use of opiate in Group I (P = 0.019). Early mobilization of the patients was significantly higher in Group I (P = 0.031). The rate of pneumonia and re-admission to the intensive care unit was higher in Group II (P = 0.017 and 0.023, respectively). The rate of pain-free patients at discharge was significantly higher in Group I (P = 0.028). A 2-week follow-up after hospital discharge showed parasternal hypoesthesia to be more in Group II (P = 0.034). Significant patient contentment in Group I was noticed (P = 0.014). Chronic post-thoracotomy pain (CPTP) was higher in Group II (P = 0.016). CONCLUSIONS ICNP without harvesting an intercostal muscle flap achieves excellent outcomes in controlling acute post-thoracotomy pain and CPTP. ICNP is an effective, simple method to perform, and it should be considered as standard in performing thoracotomy.
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OBJECTIVES The importance of phrenic nerve preservation during pneumonectomy remains controversial. We previously demonstrated that preservation of the phrenic nerve in the immediate postoperative period preserved lung function by 3-5% but little is known about its long-term effects. We, therefore, decided to investigate the effect of temporary ipsilateral cervical phrenic nerve block on dynamic lung volumes in mid- to long-term pneumonectomy patients. METHODS We investigated 14 patients after a median of 9 years post pneumonectomy (range: 1-15 years). Lung function testing (spirometry) and fluoroscopic and/or sonographic assessment of diaphragmatic motion on the pneumonectomy side were performed before and after ultrasonographic-guided ipsilateral cervical phrenic nerve block by infiltration with lidocaine. RESULTS Ipsilateral phrenic nerve block was successfully achieved in 12 patients (86%). In the remaining 2 patients, diaphragmatic motion was already paradoxical before the nerve block. We found no significant difference on dynamic lung function values (FEV1 'before' 1.39 ± 0.44 vs FEV1 'after' 1.38 ± 0.40; P = 0.81). CONCLUSIONS Induction of a temporary diaphragmatic palsy did not significantly influence dynamic lung volumes in mid- to long-term pneumonectomy patients, suggesting that preservation of the phrenic nerve is of greater importance in the immediate postoperative period after pneumonectomy.
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Film-based photographic collections of nitrate negatives pose major challenges to preservation and access because of unstable media and the lack of item-level indexing. Digitization offers an opportunity to capture the content of deteriorating negatives, to extend access to them, and to restore their usefulness as information resources. Digitization as a preservation strategy has been the subject of ongoing debate. This article contributes to the discussion by exploring access to and the preservation of film-based photographic collections and by presenting the digiti- zation project at the American Geographical Society Library as a case study. The project, Saving and Sharing the AGS Library’s Historic Nitrate Negative Images, was undertaken from 2010 to 2012 to preserve and provide access to over 69,000 nitrate negatives from its historic collections.
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"August 1982"--Vol. 1.
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Nowadays the great public libraries in Bulgaria are gaining the appearance of digital centers which provide new informational resources and services in the digital space. The digital conversion as a way of preservation is one of the important priorities of Regional Public Library in Veliko Tarnovo. In the last few years we persistently search for possible ways of financing by national and foreign programs in this direction. In the beginning the strategy was oriented to digitalization of the funds with most urgent conversion – these of the local studies periodicals from 1878 till 1944 year. The digitalization of funds will create conditions of laying the basement of full text database of Bulgarian periodical publications. The technology that is offered gives opportunities for including other libraries in the Unified index, which can develop it into a National Unified index of periodical publications. The integrated informational environment that is created is an attractive, comfortable and useful place for work in home or at work for researchers, historians, art experts, bibliographers. The library readers use very actively all informational services of the library internet page and work competently with the on-line indexes provided there, they find the necessary title, which can be demanded later for usage in home or in the library, using electronic means again.
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The project demonstrates the use of modern technologies for preservation and presentation of the cultural and historical heritage. The idea is a database of cultural and historical heritage sites to be created applying three dimensional laser scanning technology and a combination of geodetic and photogrammetric methods and shooting techniques. For the purposes of carrying out this project, we have focused on some heritage sites in the central part of Sofia. We decided to include these particular buildings because of the fact that there is hardly another city in the world where within a radius of 400 m are located four temples of different religions - Jewish, Muslim, Orthodox and Catholic. In the recent years, preservation of cultural heritage has been increasingly linked to objectives of sustainable development. Today, it has become clear that cultural heritage is also an economic resource that should be used for further economic development (through compulsory preservation of its authentic cultural values). There has been a more active public debate on the role of cultural heritage, regarding the following topics: improving the quality of life through development of cultural tourism, leading to an increase of the employment rate, constantly improving the business climate, etc. Cultural heritage preservation is becoming one of the priority objectives of the urban development policy. The focus has been shifted to new ways of preservation, mainly combinations of sophisticated technological solutions and their application for the purposes of preservation and dissemination of the cultural heritage.
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In ocean margin sediments both marine and terrestrial organic matter (OM) are buried but the factors governing their relative preservation and degradation are not well understood. In this study, we analysed the degree of preservation of marine isoprenoidal and soil-derived branched glycerol dialkyl glycerol tetraethers (GDGTs) upon long-term oxygen exposure in OM-rich turbidites from the Madeira Abyssal Plain by analyzing GDGT concentrations across oxidation fronts. Relative to the anoxic part of the turbidites ca. 7-20% of the soil-derived branched GDGTs were preserved in the oxidized part while only 0.2-3% of the marine isoprenoid GDGT crenarchaeol was preserved. Due to these different preservation factors the Branched Isoprenoid Tetraether (BIT) index, a ratio between crenarchaeol and the major branched GDGTs that is used as a tracer for soil-derived organic matter, substantially increases from 0.02 to 0.4. Split Flow Thin Cell (SPLITT) separation of turbidite sediments showed that the enhanced preservation of soil-derived carbon was a general phenomenon across the fine particle size ranges (<38 ?m). Calculations reveal that, despite their relatively similar chemical structures, degradation rates of crenarchaeol are 2-fold higher than those of soil-derived branched GDGTs, suggesting preferential soil OM preservation possibly due to matrix protection.
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Thesis (Master's)--University of Washington, 2016-06
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Master final project submitted to the faculty of the Historic Preservation Program of the School of Architecture, Planning, and Preservation of the University of Maryland, College Park, in partial fulfillment of the requirements for the degree of Master of Historic Preservation, 2013.
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The short shelf life of mushrooms is a barrier for their distribution and, therefore, there has been extensive research to find technologies that ensure the preservation of mushrooms, maintaining their organoleptic and nutritional properties (1]. Irradiation has proved its technological feasibility to be safely used in the reduction of food losses, being recognized by international organizations as a valid conservation alternative in extending shelflife of many foods. The aim of the present work was to validate the use of 2 kGy dose of gamma radiation to maintain chemical composition of wild mushrooms. Boletus pinophilus Pihit & Dermek and Clitocybe subconnexa Murrill wild samples were obtained in Tnis-os-Montes; subsequently, the samples were divided in two groups: control (non-irradiated, 0 kGy) and irradiated (2 kGy). The irradiation of the samples was performed in a 6°Co experimental chamber. Moisture, protein, fat, carbohydrates and ash were determined following the standard procedures [2]. Free sugars and tocopherols were determined by high performance liquid chromatography coupled to a refraction index detector (HPLC-RI) and a fluorescence detector, respectively; fatty acids were determined by gas-liquid chromatography with flame ionization detection (GC-FID) [3]. The protein and ash content was preserved in both groups, although the sugars and tocopherols decreased in the irradiated samples. Sugars and fatty acids showed significant changes after irradiation treatment, particularly in B. pinophillus, nevertheless, the magnitude of the obtained differences did not seem to be sufficient to affect the chemical profiles of the assayed mushrooms. Overall, the detected chemical changes might be considered as allowable, in view of the high advantages offered by gamma irradiation at decontamination and/or disinfestation level.