89 research outputs found
Essays on monetary economics
No full textIn my dissertation, I attempt to shed new light on the impact of central bank behavior. The first chapter proposes indexes of monetary policy design characteristics in line with inflation targeting (IT). Indexes aim to provide a useful classification of central banks and to examine whether IT intensity matters for sacrifice ratio and inflation persistence. Results show that U.S. and Japan are ranked close to early targeters. Armenian central bank is detected to perform remarkably well as opposed to the literature's descriptions. Noteworthy structural changes are noticed in Mexico and Peru. Higher index level significantly reduces OECD countries' inflation persistence through increased transparency. Higher intensity among targeters does not deliver significantly lower sacrifice ratio or inflation persistence. Announcing official targets does not provide additional benefits. Low degree of central bank discretion and limited financing of the government significantly decrease the sacrifice ratio among OECD countries and in the full cross-sectional sample respectively. Institutional design features need to be mature enough in order to benefit from inflation targeting. The second chapter examines the usefulness of monetary aggregates. A number of dynamic stochastic general equilibrium models (DSGE) and econometric time series models are jointly specified; including vector autoregressive (VAR), random walk (RW), and various autoregressive (AR) and AR with exogenous variable type models (ARX). Model performance is evaluated via novel testing methods developed for assessing predictive and simulation accuracy. Money is found to matter for inflation simulation purposes in simple econometric models, such as ARX models. With regard to predictive point and density analysis, when complex models are examined, M2 enters into the forecast-best VAR-type inflation models. Model selection is found to be sensitive to researcher’s objective function, to target variable and forecast horizon. Particularly, when the objective is policy analysis, the examination of multivariate models show that DSGE-type models often outperform at longer horizons and mainly for output forecasts. In contrast, VAR-type models win for simulation purposes and short-horizon inflation forecasts. However, univariate models without money generally dominate theoretical and atheoretical multivariate models both with and without money from both forecasting and simulation standpoint.Ph. D.Includes bibliographical referencesIncludes vitaby Demet Tunal
The relationship between wayfinding performance, spatial layout and landmarks in virtual environments
No full textEnvironmental factors, including landmarks that affect people’s wayfinding performance in unfamiliar environments have been discussed in a great number of studies. However, there is still no consensus on the factors that shape people’s performance or what makes a landmark preferable during wayfinding. Hence, this study aims to understand the impact of different spatial layouts, environmental conditions and landmarks on people’s wayfinding performance, and the factors that make landmarks salient.
Sea Hero Quest (SHQ), an online game that has been played by more than 4.3 million people from 2016 to date, is selected as a case study to investigate the impact of different environments and other factors, in particular landmarks. Forty-five wayfinding levels of SHQ are analysed and compared using Geographic Information System (GIS) and Space syntax axial, segment and visibility graph analyses. A cluster analysis is conducted to examine the relationship between levels. Varying conditions associated with landmarks, weather and maps were taken into consideration. In order to investigate the process of selecting landmarks, visual, structural (whether landmarks are global or local) and cognitive saliency are analysed using web-based surveys, saliency algorithms and the visibility of landmarks.
Results of this study show that the complexity of layouts plays a major role in wayfinding; as the complexity of layout increases, so does the time taken to complete the wayfinding task. Similarly, the weather condition has an effect; as the weather becomes foggy and visibility decreases, the time taken to complete the wayfinding task increases. It is discovered that landmarks that are visible for more than 25% of a journey can be defined as global landmarks whereas the rest can be defined as local landmarks. Findings also show that landmarks that are visually salient (objects with a unique colour and size) and structurally salient (objects that are closer to people) are registered more by people in unfamiliar environments.
This study contributes to the existing literature by exploring the factors that affect people’s wayfinding performance by using the largest dataset in the field (so providing more accurate results), focusing on 45 different layouts (while current research studies mostly focus on one or two different layouts), by proposing a threshold to distinguish global and local landmarks, and analysing visual, structural and cognitive saliency through various measures
Impact of Bridges on Spatial Transformation of Urban Pattern: The case of Golden Horn, Istanbul
No full text[EN] Transportation projects especially subways, bridges and new transportation modes gained importance in İstanbul in the last decades. The Golden Horn Metro Bridge, which connects two parts of the European side of İstanbul and has a station on the bridge, has caused criticisms not just because of having these unique characteristics but also because of the effects of the bridge on the silhouette of Historical Peninsula. The main aim of this paper is to analyze the impact of bridges on urban pattern and to explore the different influences of metro and vehicular bridges. Within this scope, three bridges located over the Golden Horn, which created connections between historical site of İstanbul and the newly developed CBD, are chosen as study case. Areas within 1km zones around the bridges are analysed separately, and the urban pattern (street pattern, block size, building utilization) is investigated comparatively through GIS. The layers of the past geographies (Historical GIS) and the Space Syntax (angular segment based integration and choice) analyses are conducted for demonstrating the changes in the spatial organization. The findings indicate that the study area has transformed into more divided streets and urban blocks and the number of buildings increased through time. Moreover, it is observed that the metro-rail bridge system has less impact on urban pattern when compared with the vehicular bridges. This study contributes to urban planning/design not only by analysing comparatively the transformation of the urban pattern during the pre- and post-construction processes of the bridges but also by evaluating the impact of the bridges through a quantitative and innovative method.Yesiltepe, D.; Kubat, A. (2018). Impact of Bridges on Spatial Transformation of Urban Pattern: The case of Golden Horn, Istanbul. En 24th ISUF International Conference. Book of Papers. Editorial Universitat Politècnica de València. 935-942. https://doi.org/10.4995/ISUF2017.2017.6059OCS93594
Evaluation of the ımpact of glycemic control on mean platelet volume and platelet activation in children with type 1 diabetes
No full textObjective: The studies evaluating cases with type 1 diabetes mellitus (T1DM) and type 2 diabetes mellitus (T2DM) in the adult population reported hyperreactive platelets and increased activation of prothrombotic factors, resulting in an increased risk of thrombosis. The aim of this study was to evaluate the effects of poor glycemic control and the duration of diabetes on platelet parameters in pediatric population. Methods: The study included 366 children, out of which 144 (39.3%) were included in the T1DM group and 222 (60.6%) in the healthy control group. The platelet count, mean platelet volume (MPV), platelet distribution width and plateletcrit values were recorded. The children with T1DM were divided into three groups as per their glycated hemoglobin (HbA1c) levels, good ([removed]9%). Results: No significant difference in the MPV level between the T1DM (7.41 ± 1.49 fl) and control (7.15 ± 1.23 fl) groups was observed. However, the MPV levels were significantly higher in the poor glycemic control group than in the healthy control group (p = 0.026). Furthermore, as the duration of diabetes and HbA1c levels increased, the MPV levels also increased (p < 0.001, p = 0.441). Conclusion: This study suggested as the duration of diabetes and HbA1c levels increased, the MPV levels also increases. Evaluation of hematological parameters can be a cheap and useful method in the evaluation of diabetes regulation in patients with diabetes. © 2022 The Author(s) [2022]. Published by Oxford University Press. All rights reserved
Exploring the relationship between children’s physical activity levels and their obesity status in urban and rural areas: a review of the existing literature
No full textThe relationship between children’s obesity and their physical activity levels has been widely studied in urban areas; however, the literature related to rural areas is much more limited. In this review study, we will focus on papers that compare children’s physical activity levels with their obesity status in both urban and rural areas to understand the consensuses and gaps in the literature, and to define the factors that can be used to analyse the environments. The review will start by considering papers on children’s body mass index (BMI) and physical activity levels in urban and rural areas in general, and it will then focus on how children travel to school in urban and rural areas and how this relates to BMI. In addition to a list of environmental measures, the impacts of sedentary behaviour and socio-economic status will also be explored. This review is expected to be significant since it does not only focus on urban areas, but it examines the situation in both urban and rural areas to provide insights for future studies
Built environment, sedentary behaviour and air quality impact on asthmatic and obese children : a review of existing literature
No full textAir born pollutants are the cause of respiratory illnesses (i.e asthma and rhinitis) and their effects on vulnerable populations, particularly obese children, are of concern for the many. Nonetheless, we needed a pandemic based on airborne virus (COVID-19) to raise the awareness and observe with more detail the effects of poor air quality. This study looks at the literature to understand the impact of the built environment, sedentary behaviour and air quality on children’s quality of life. We aim to look at the day-to-day activities, walking behaviour from school to home/home to school, as well as the environmental factors that shape these behaviours (e.g. land use, block size, building density) to understand the health implications, exposure to air pollution indoors and outdoors and effects on obesity. Finally, we discuss further work for design and architecture research to help to identify and improve children’s health and to evaluate how they interact with the built environment. The method will explore mapping these interactions (GIS) analysing the built environment and street connectivity and how we can convert them on experiences through knowledge mapping to draw the further learning opportunities
The effects of perceived and objective measures of home-environment on transportation and recreational walking among children
No full textDue to copyright restrictions, the access to the full text of this article is only available via subscription.This study explores the relative association of objective and perceived environmental factors with recreational and transportation walking behaviour. Randomly selected parents of students (ages 12-14) at 10 elementary schools (N=1000) located in Istanbul, Turkey, completed questionnaires about their socio-demographic characteristics, neighbourhood environment, and their children’s physical activity. Home-environments (400 and 800 meter buffers) were evaluated through GIS-based land-use, segment-based street connectivity measures, and street-level topography. In addition, detailed field surveys related to pedestrian quality attributes were conducted within home-environments. Logistic regression was used to investigate the relationships between recreation and transportation-related walking and objective and perceived measures of the built form. Findings of the study indicate that both types of walking behaviour are associated with different perceived and objective environmental attributes. More importantly, preliminary results suggest street network connectivity measured at the segment-level is significantly associated with walking behaviours. Thus, it can be argued that modifications to the home-environment may help change hence children’s walking behaviour
The Effects of Street Network Layout on Walking to School
No full textData for this cross-sectional study were drawn from questionnaires conducted in 10 elementary schools (1000 students, ages 12-14) located in Istanbul, Turkey. School environments (1600 meter buffers around the school) were evaluated through GIS-based land-use data (parcel level land use density) and street-level topography. Street networks within the same buffers were evaluated by using angular segment analysis (Integration and Choice) implemented in Depthmap as well as two segment-based connectivity measures, namely Metric and Directional Reach implemented in GIS. Segment Angular Integration measures how accessible each space from all the others within the radius using the least angle measure of distance. Segment Angular Choice which measures how many times a space is selected on journeys between all pairs of origins and destinations. Metric Reach captures the density of streets and street connections accessible from each individual road segment. Directional Reach measures the extent to which the entire street network is accessible with few direction changes. In addition, socio-economic characteristics (annual income, car ownership, education-level) of parents, obtained from parental questionnaires, were also included in the analysis. It is shown that surrounding street network configuration is strongly associated with both walk-mode shares and average walking distances to/from schools when controlling for parental socio-demographic attributes as well as land-use compositions and topographic features in school environments. More specifically, findings suggest that the scale at which urban form has an impact on pedestrian travel is considerably larger than a few blocks around the school
Tracing the path of cycling initiatives : Revisiting Lancaster's CDT program and unravelling current policies
No full textIntroduction Active modes of transportation have gained significant prominence in many cities, with governments and public health organizations increasingly advocating for cycling. While policy and planning decisions are actively aimed at boosting cycling rates, their long-term impact remains somewhat uncertain. This study seeks to shed light on the enduring effects of policy and planning decisions on cycling and outlines potential steps for sustainable progress. Methods To achieve this, we have chosen Lancaster, UK, as our case study, with a specific focus on the UK Government-funded Cycling Demonstration Towns (CDTs) program that operated from 2005 to 2011. Our approach involves revisiting this program and the changes in the city through a multi-pronged methodology: conducting surveys with cyclists (n = 65), engaging in interviews with personnel from Lancaster City and Lancashire County Council (n = 3), and analyzing cyclist numbers at specific locations (n = 5). Results The findings of our study reveal the positive influence of the CDTs program on cycling rates and the perspectives of cyclists in Lancaster. However, after the program's completion, progress has been somewhat gradual, drawing attention to specific areas in need of improvement, particularly infrastructure and safety measures. Conclusions In conclusion, we delve into potential strategies for implementation, not only within Lancaster but also for other CDTs and cities aspiring to promote cycling initiatives. This underscores the effectiveness of such programs and decisions in the short-term while emphasizing the critical importance of sustained investments in infrastructure and maintenance for long-term impact
Synthesis and Characterization of Hydroxyapatite Powders From Eggshell For Functional Biomedical Application
No full textBulus, Erdi (Arel Author), İsmik, Deniz (Arel Author), Mansuroğlu, Demet Sezgin (Arel Author), Şahin, Yeşim Müge (Arel Author)Apatitic phosphates are considered within the category of bioceramics. HA and its derives are used of in the fields of medicine, orthopedics and dentistry in order to support a grow up of new bone cells. HA structures have a high biocompability and are widely in biomedical applications. On the other hand, synthesis of HA structures necessitates complex technologies (microwave sintering, hydrothermal synthesis etc.) and their production costs high. This study aims the production of nano apatitic structures with great biocompability from a natural material. Simple hotplate method was used to obtain natural, nano scale HA from eggshells. After calcination and sintering processes at different temperatures, the obtained apatitic phosphate powders have been structurally characterized by infrared spectroscopy (FT-IR) and X-ray diffraction (XRD). Morphological investigation has been conducted by FEG-SEM images. Biological investigations have been carried out for the produced nanosized bioceramics and the results reveal that these nanomaterials are promising for tissue engineering purposes
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