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Bulunan: 73 Adet 0.001 sn
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OR problems related to Home Health Care: A review of relevant routing and scheduling problems

Cissé, M. | Yalçındağ, S. | Kergosien, Y. | Şahin, E. | Lenté, C. | Matta, A.

Review | 2017 | Operations Research for Health Care13-14 , pp.1 - 22

The home health care routing and scheduling problem (HHCRSP) consists of designing a set of routes used by care workers to provide care to patients who live in the same geographic area and who must be treated at home. Hence, care activities, i.e., patient visits, must be planned to minimize measures, such as travel costs or to maximize the quality of service delivered to patients while respecting several constraints. The HHCRSP is an extension of the vehicle routing problem (VRP) with unusual side-constraints that make the issues difficult to solve. This paper details a comprehensive overview of recent OR models developed for the HH . . .CRSP, a field that has received a great amount of attention in recent years. To summarize the existing research contributions, we initially identify the most relevant features considered in the HHCRSP models, and then analyze the existing literature according to the way the different studies formulate the constraints and objective functions. We then provide an overview of methods developed to solve the HHCRSP and discuss future research directions. © 2017 Elsevier Lt Daha fazlası Daha az

A survey on the practical use of UML for different software architecture viewpoints

Ozkaya, M. | Erata, F.

Article | 2020 | Information and Software Technology121 , pp.1 - 22

Context: Software architecture viewpoints modularize the software architectures in terms of different viewpoints that each address a different concern. Unified Modeling Language (UML) is so popular among practitioners for modeling software architectures from different viewpoints. Objective: In this paper, we aimed at understanding the practitioners’ UML usage for the modeling of software architectures from different viewpoints. Method: To this end, 109 practitioners with diverse profiles have been surveyed to understand practitioners’ UML usage for six different viewpoints: functional, information, concurrency, development, deployme . . .nt, and operational. Each viewpoint has been considered in terms of a set of software models that can be created in that viewpoint. Results: The survey includes 35 questions for different viewpoint models, and the results lead to interesting findings. While the top popular viewpoints for the UML-based software architecture modeling are the functional (96%) and information (99%) viewpoints, the least popular one is the operational viewpoint that is considered by 26% of the practitioners. The top popular UML modeling tool is Enterprise Architect regardless of the viewpoints considered. Concerning the software models that can be created in each viewpoint, UML's class diagram is practitioners’ top choice for the functional structure (71%), data structure (85%), concurrency structure (75%), software code structure (34%), and system installation (39%), and system support (16%) models; UML's sequence diagram is the top choice for the data lifecycle models (47%); UML's deployment diagram for the physical structure (71%), mapping between the functional and physical components (53%), and system migration (21%) models; UML's activity diagram for the data flow (65%), software build and release processes (20–22%), and system administration (36%) models; UML's component diagram for the mapping between the functional and concurrent components (35%), software module structure (47%), and system configuration (21%) models; and UML's package diagram for the software module structure (47%) models. © 2020 Elsevier B.V Daha fazlası Daha az

An appointment scheduling framework to balance the production of blood units from donation

Baş, S. | Carello, G. | Lanzarone, E. | Yalçındağ, S.

Article | 2018 | European Journal of Operational Research265 ( 3 ) , pp.1124 - 1143

Blood is fundamental in several care treatments and surgeries, and plays a crucial role in the health care system. It is a limited resource, as it can be produced only by donors and its shelf life is short; thus, the blood donation (BD) system aims at providing adequate supply of blood units to transfusion centers and hospitals. An effective collection of blood units from donors is fundamental for adequately feeding the entire BD system and optimizing blood usage. However, despite its relevance, donation scheduling is only marginally addressed in the literature. In this paper we consider the Blood Donation Appointment Scheduling (BD . . .AS) problem, aiming at balancing the production of the different blood types among days in order to provide a quite constant feeding of blood units to the BD system. We propose a framework for the appointment reservation that accounts for both booked donors and donors arriving without a reservation. It consists of an offline Mixed Integer Linear Programming (MILP) model for preallocating time slots to blood types, and an online prioritization policy to assign a preallocated slot when the donor calls to make the reservation. © 2017 Elsevier B.V Daha fazlası Daha az

Boron nitride nanotubes included thermally cross-linked gelatin-glucose scaffolds show improved properties

Şen, Ö. | Çulha, Mustafa

Article | 2016 | Colloids and Surfaces B: Biointerfaces138 , pp.41 - 49

Boron nitride nanotubes (BNNTs) are increasingly investigated for their medical and biomedical applications due to their unique properties such as resistance to oxidation, thermal and electrical insulation, and biocompatibility. BNNTs can be used to enhance mechanical strength of biomedical structures such as scaffolds in tissue engineering applications. In this study, we report the use of BNNTs and hydroxylated BNNTs (BNNT-OH) to improve the properties of gelatin-glucose scaffolds prepared with electrospinning technique. Human dermal fibroblast (HDF) cells are used for the toxicity assessment and cell seeding studies. It is found t . . .hat the addition of BNNTs into the scaffold does not influence cell viability, decreases the scaffold degradation rate, and improves cell attachment and proliferation compared to only-gelatin scaffold. © 2015 Elsevier B.V Daha fazlası Daha az

A solution to the classification problem with cellular automata

Uzun, A.O. | Usta, T. | Dündar, E.B. | Korkmaz, E.E.

Article | 2018 | Pattern Recognition Letters116 , pp.114 - 120

Classification is the task of labeling data instances by using a trained system. The data instances consist of various attributes and in order to train the system, a set of already labeled data is utilized. After the training process, success rate of the system is determined with separate test sets. Various machine learning algorithms are proposed for the solution of the problem. On the other side, Cellular Automata (CA) provide a computational model consisting of cells interacting with each other based on some predetermined rules. In this study, a new approach is proposed for the classification problem based on CA. The method maps . . .the data instances in the training data set to cells of an automaton based on the attribute values. When a CA cell receives a data instance, this cell and its neighbors are heated based on a heat transfer function. A separate automaton is heated for each class in the data set and hence a characteristic heat map is obtained for each class at the end of the procedure. Then new instances are classified by using these heat maps. The success rate of the algorithm is compared with the results of other known classification algorithms in the experiments carried out. © 2018 Elsevier B.V Daha fazlası Daha az

Electrochemically designed interfaces: Hydroxyapatite coated macro-mesoporous titania surfaces

Utku, F.S. | Seckin, E. | Goller, G. | Tamerler, C. | Urgen, M.

Conference Object | 2015 | Applied Surface Science350 , pp.62 - 68

Titanium-based implants are key weight-bearing materials in biomedical engineering due to their excellent bulk mechanical properties and biocompatibility. Designing tissue-material interfaces of titanium implants is essential for an increase in osteointegration of engineered implant materials. Surface morphology is a crucial determinant in the construction of biocompatible and osteointegrative orthopedic and dental implants. Biomimicry of the structural features of bone, specifically its macro-to-mesoporosity, may enable the bone cells to osteointegrate, attain and maintain a physiological strain level. In this study, the surface ch . . .emistry and morphology of commercially pure titanium plates were modified using electrochemistry. Titanium oxide substrates were prepared by dual acid polishing and alkaline anodization using 0.1 M KOH in an electrochemical cell with a stainless steel cathode and an anodic voltage of 40 V at 20 °C for 3 min. FE-SEM characterization revealed macro-mesoporous anodized titania surfaces, which were coated by hydroxyapatite using simulated body fluid and pulsed electrochemical deposition at 80 °C, while unprocessed commercially pure titanium surfaces were used as controls. The calcium phosphate deposit on titania plates was characterized as calcium-deficient carbonated hydroxyapatite using XRD, FTIR and FE-SEM, whereas the deposit on non-porous, non-functionalized titanium surfaces was characterized as carbonated apatite. The adhesion strength of the hydroxyapatite coated titania surfaces was 38 ± 10 MPa, implying that these surfaces may be suitable for biological and chemical functionalization of medical implants to tune bioactivity, including delivering drugs. © 2015 Elsevier B.V. All rights reserved Daha fazlası Daha az

Electric field effect on the refractive index changes in a Modified-Pöschl-Teller quantum well

Ustoglu Unal, V. | Aksahin, E. | Aytekin, O.

Article | 2013 | Physica E: Low-Dimensional Systems and Nanostructures47 , pp.103 - 108

The effect of an applied static field is studied on the optical properties of a quantum well (QW) represented by a Modified Pöschl-Teller potential. This potential allows analytical solution of the eigen-values and eigen-functions which in turn makes the numerical calculation of optical properties quite transparent. In this work, we concentrate on the linear and nonlinear refractive index changes. Comparison of the results using the finite Modified-Pöschl-Teller (MPT) potential with those in the literature using the infinite Pöschl-Teller (PT) potential shows that the main difference between the two potentials is coming from the dep . . .th differences of the two wells. The changes in the refractive indices are bigger than those using infinite PT potential. If one wants a larger change in the total refractive index, one should try to reduce the applied electric fields and the optical intensities. © 2012 Elsevier B.V. All rights reserved Daha fazlası Daha az

The influence of different calorie restriction protocols on serum pro-inflammatory cytokines, adipokines and IGF-I levels in female C57BL6 mice: Short term and long term diet effects

Dogan, S. | Ray, A. | Cleary, M.P.

Article | 2017 | Meta Gene12 , pp.22 - 32

Calorie restriction (CR) is an effective intervention to prevent chronic diseases including cancer. Although many factors, i.e., sex hormones, IGF-I and mTOR have been studied in response to CR, the molecular mechanisms of CR remain to be identified. Our objective was to determine the short and long-term effects of different CR protocols on pro-inflammatory cytokines. Our hypothesis was that Intermittent CR (ICR) would result in greater inhibition of pro-inflammatory serum cytokines compared to Chronic CR (CCR) as we previously found ICR to be more protective in the prevention of mammary tumor development. From ten weeks of age fema . . .le C57BL6 mice were maintained on either ad libitum (AL) fed, ICR or CCR protocols (overall CR of ~ 75% of AL) for up to 74 weeks of age. Blood samples were collected for measurements of serum interleukin-6 (IL-6), tumor necrosis factor–alpha (TNF-?), adiponectin, leptin, IGF-I and insulin at specified ages. For ICR mice samples were collected following 3 weeks of restriction (ICR-R) and after one week of refeeding (ICR-RF). In general, both modes of CR significantly reduced serum IL-6, TNF-?, IGF-I and leptin levels compared to AL with IL-6 levels 24 and 3.5 fold and TNF-? levels t 11 and 1.5 fold lower in ICR and CCR groups, respectively at study termination. There was a trend for adiponectin and insulin to be highest in ICR-RF mice. Body weights were positively correlated with IL-6, TNF-?, insulin and leptin but negatively correlated with adiponectin-to-leptin ratio. Moreover, there was a positive correlation between IL-6 and TNF-?. Beneficial effects of ICR may function through pro-inflammatory cytokine pathways. © 2017 Elsevier B.V Daha fazlası Daha az

Time-frequency analysis of the event-related potentials associated with the Stroop test

Ergen, M. | Saban, S. | Kirmizi-Alsan, E. | Uslu, A. | Keskin-Ergen, Y. | Demiralp, T.

Article | 2014 | International Journal of Psychophysiology94 ( 3 ) , pp.463 - 472

Multiple executive processes are suggested to be engaged at Stroop test, and time-frequency analysis is acknowledged to improve the informative utility of EEG in cognitive brain research. We aimed to investigate event-related oscillations associated with the Stroop test. EEG data was collected from 23 healthy volunteers while they performed a computer version of Stroop test. Both evoked (phase-locked) and total (phase-locked. +. non-phase-locked) oscillatory responses in the EEG were analyzed by wavelet transform. Data from the congruent (color-word matching) and incongruent stimuli (color-word non-matching) conditions are compared. . . . In the incongruent condition, N450 wave was more negative and amplitude of the late slow wave was more positive. In the time-frequency plane, the fronto-central total theta amplitude (300-700. ms) was larger in the incongruent condition. The evoked delta (250-600. ms) was larger in the congruent condition particularly over parieto-occipital regions. The larger frontal theta response in the incongruent condition was associated with the detection of interference and inhibition of the response to task-irrelevant features, while the larger evoked delta in the congruent condition was suggestive of the easier decision process owing to congruency between the physical attribute and the verbal meaning of the stimuli. Furthermore, in the incongruent condition, amplitude of the occipital total alpha in the very late phase (700-900. ms) was smaller. This prolonged desynchronization in the alpha band could be reflecting augmentation of attentional filters in visual modality for the next stimulus. These multiple findings on EEG time-frequency plane provide improved description of the overlapping processes in Stroop test. © 2014 Elsevier B.V Daha fazlası Daha az

Evaluation of Student Information System (SIS) in Terms of User Emotion, Performance and Perceived Usability: A Turkish University Case (An Empirical Study)

Demirkol, D. | Seneler, C.

Conference Object | 2019 | Procedia Computer Science158 , pp.1033 - 1051

Student Information System (SIS) has abundant functions in order to maintain academic workflow. Besides, user experience on SIS is critical so as to sustain its functions. Although user experience of various information systems (IS) has been studied in the literature related to user emotion, performance and perceived usability, this is not the case for the SIS. In order to fill this gap, this empirical study has been investigated how student's backgrounds affect their experiences with a SIS in terms of their emotion, performance and perceived usability. The study was administered in the one of the universities of Turkey with a sampl . . .e of 32 participants. Participants were divided technology prone group and other group to measure the differences among the groups. Participants were asked to perform a number of tasks on the system; the tasking being carefully chosen to direct participants to different aspects of the SIS. In addition, to get more insight about participants' experiences, EWPL-TR, SUS-TR and Overall Assessment Questions were directed to them. This study showed significant differences among user's emotion, performances and perceived usability depending on their specific demographic backgrounds. The results of this research will be important for developers of SIS and similar websites who want to take the advantage of developing supportive systems by focusing on users' demographic backgrounds. © 2019 The Authors. Published by Elsevier B.V Daha fazlası Daha az

Influence of EDC/NHS coupling chemistry on stability and cytotoxicity of ZnO nanoparticles modified with proteins

Keleştemur, S. | Altunbek, M. | Çulha, Mustafa

Article | 2017 | Applied Surface Science403 , pp.455 - 463

The toxicity of ZnO nanoparticles (NPs) is a growing concern due to its increasing use in several products including sunscreens, paints, pigments and ceramics for its antibacterial, antifungal, anti-corrosive and UV filtering properties. The toxicity of ZnO NPs is mostly attributed to the Zn 2+ release causing an increase in the intracellular reactive oxygen species (ROS) level. The surface modification with a biocompatible ligand or a polymer can be a good strategy to reduce dissolution based toxicity. In two previous studies, the conflicting results with EDC/NHS coupling chemistry for ZnO NPs were reported. In this study, the same . . . surface modification strategy with an emphasis on the stability of ZnO NPs is clarified. First, the density of –OH groups on the ZnO NPs is increased with hydrogen peroxide (H 2 O 2 ) treatment, and then a silica coating on the ZnO NPs (Si-ZnO) surface is performed. Finally, a covalent attachment of bovine serum albumin (BSA) on three different concentrations of ZnO-Si is carried out by EDC/NHS coupling chemistry. ZnO NPs have a very high dissolution rate under acidic conditions of EDC/NHS coupling chemistry as determined from the ICP-MS analysis. In addition, the amount of ZnO NPs in coupling reaction has an important effect on the dissolution rate of Zn 2+ and dependently BSA attached on the ZnO NP surfaces. Finally, the cytotoxicity of the BSA modified Si-ZnO NPs on human lung cancer (A549) and human skin fibroblast (HSF) is evaluated. Although an increased association of BSA modified ZnO NPs with cells was observed, the modification significantly decreased their cytotoxicity. This can be explained with the decreased active surface area of ZnO NPs with the surface modification. However, an increase in the mitochondrial depolarization and ROS production was observed depending on the amount of BSA coverage. © 2017 Elsevier B.V Daha fazlası Daha az

Effect of reaction mixture composition and silica source on size distribution of zeolite X crystals

Tekin, R. | Bac, N. | Warzywoda, J. | Sacco, A.

Article | 2015 | Journal of Crystal Growth411 , pp.45 - 48

Zeolite X crystals were synthesized by hydrothermal crystallization from gels with different compositions. The syntheses were performed at 95 °C using different silica sources such as sodium metasilicate anhydrous, sodium metasilicate pentahydrate, silicate solution and Cab-O-Sil. Triethanolamine was used in some syntheses in order to grow large crystals. Zeolite X crystals with diameters in the range of 1-220 µm were obtained, and Cab-O-Sil in concert with triethanolamine yielded the largest crystals. © 2014 Elsevier B.V.

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