Relationship of smartphone use severity with sleep quality, depression, and anxiety in university students

Background and aims The usage of smartphones has increased rapidly in recent years, and this has brought about addiction. The aim of the current study was to investigate the relationship between smartphone use severity and sleep quality, depression, and anxiety in university students. Methods In total, 319 university students (203 females and 116 males; mean age = 20.5 ± 2.45) were included in the study. Participants were divided into the following three groups: a smartphone non-user group (n = 71, 22.3%), a low smartphone use group (n = 121, 37.9%), and a high smartphone use group (n = 127, 39.8%). All participants were evaluated using the Pittsburgh Sleep Quality Index, Beck Depression Inventory, Beck Anxiety Inventory; moreover, participants other than those in the smartphone non-user group were also assessed with the Smartphone Addiction Scale. Results The findings revealed that the Smartphone Addiction Scale scores of females were significantly higher than those of males. Depression, anxiety, and daytime dysfunction scores were higher in the high smartphone use group than in the low smartphone use group. Positive correlations were found between the Smartphone Addiction Scale scores and depression levels, anxiety levels, and some sleep quality scores. Conclusions The results indicate that depression, anxiety, and sleep quality may be associated with smartphone overuse. Such overuse may lead to depression and/or anxiety, which can in turn result in sleep problems. University students with high depression and anxiety scores should be carefully monitored for smartphone addiction

Designing the Liver Allocation Hierarchy: Incorporating Equity and Uncertainty

Liver transplantation is the only available therapy for any acute or chronic condition resulting in irreversible liver dysfunction. The liver allocation system in the U.S. is administered by the United Network for Organ Sharing (UNOS), a scientific and educational nonprofit organization. The main components of the organ procurement and transplant network are Organ Procurement Organizations (OPOs), which are collections of transplant centers responsible for maintaining local waiting lists, harvesting donated organs and carrying out transplants. Currently in the U.S., OPOs are grouped into 11 regions to facilitate organ allocation, and a three-tier mechanism is utilized that aims to reduce organ preservation time and transport distance to maintain organ quality, while giving sicker patients higher priority. Livers are scarce and perishable resources that rapidly lose viability, which makes their transport distance a crucial factor in transplant outcomes. When a liver becomes available, it is matched with patients on the waiting list according to a complex mechanism that gives priority to patients within the harvesting OPO and region. Transplants at the regional level accounted for more than 50% of all transplants since 2000.This dissertation focuses on the design of regions for liver allocation hierarchy, and includes optimization models that incorporate geographic equity as well as uncertainty throughout the analysis. We employ multi-objective optimization algorithms that involve solving parametric integer programs to balance two possibly conflicting objectives in the system: maximizing efficiency, as measured by the number of viability adjusted transplants, and maximizing geographic equity, as measured by the minimum rate of organ flow into individual OPOs from outside of their own local area. Our results show that efficiency improvements of up to 6% or equity gains of about 70% can be achieved when compared to the current performance of the system by redesigning the regional configuration for the national liver allocation hierarchy.We also introduce a stochastic programming framework to capture the uncertainty of the system by considering scenarios that correspond to different snapshots of the national waiting list and maximize the expected benefit from liver transplants under this stochastic view of the system. We explore many algorithmic and computational strategies including sampling methods, column generation strategies, branching and integer-solution generation procedures, to aid the solution process of the resulting large-scale integer programs. We also explore an OPO-based extension to our two-stage stochastic programming framework that lends itself to more extensive computational testing. The regional configurations obtained using these models are estimated to increase expected life-time gained per transplant operation by up to 7% when compared to the current system.This dissertation also focuses on the general question of designing efficient algorithms that combine column and cut generation to solve large-scale two-stage stochastic linear programs. We introduce a flexible method to combine column generation and the L-shaped method for two-stage stochastic linear programming. We explore the performance of various algorithm designs that employ stabilization subroutines for strengthening both column and cut generation to effectively avoid degeneracy. We study two-stage stochastic versions of the cutting stock and multi-commodity network flow problems to analyze the performances of algorithms in this context

Proper class generated by submodules that have supplements

Thesis (Master)--Izmir Institute of Technology, Mathematics, Izmir, 2008Includes bibliographical references (leaves: 37-38)Text in English: Abstract: Turkish and Englishix, 40 leavesIn this thesis, we study the class S of all short exact sequences 0 A B C 0 where Im& has a supplement in B, i.e. a minimal elemenr in the set {V B V + Im& . B}.The corresponding elements of ExtR(C;A) are called k-elements. In general k-elements need not form a subgroup in ExtR(C;A), but in the category TR of torsion R-modules over a Dedekind domain R, S is a proper class; there are no nonzero S-projective modules and the only S-injective modules are injective R-modules in TR. In this thesis we also give the structure of S-coinjective R-modules in TR. Moreover, we define the class SB of all short exact sequences 0 A B C 0 where Im & has a supplement V in B and V in B and In & is bounded. The corresponding elements of ExtR(C;A) are called B-elements. Over a noetherian integral domain of Krull dimension 1, B-elements form a proper class. In the category TR over a Dedekind domain R, SB is a proper class; there are no nonzero SB-projective R-modules and SB-injective R-modules are only the injective R-modules. In the category TR, reduced SB-coinjective R-modules are bounded R-modules

Depolama Sürecince Bitkisel Yağların Kırmızıbiberin Kalite Parametreleri Üzerine Etkileri

Sunflower, cottonseed, hazelnut, soybean and sesame oils at the concentration of 0, 2, 4 or 6 g/100g red pepper were added into red pepper to determine the effects of the oils on color and oxidative stability during 12-month storage at room temperature. The changes in color, free fatty acid content and peroxide value were determined in 2 month intervals. Initial colors of samples were ranged between 75.26 and 79.95 (ASTA unit), and decreased as the amount of the added vegetable oils increased. Color losses were increased by increasing time for all samples while the color of the soybean oil added samples was more stable. Free fatty acid content and peroxide value of red pepper extracted oils increased significantly as the storage time increased. At the end of storage, free fatty acid content of sesame oil added red pepper was higher than that of others and the lower peroxide value was observed in the control.Ayçiçek, pamuk, fındık, soya ve susam yağları kırmızıbibere 2,4 ve 6 g/100 g kırmızıbiber oranlarında ilave edilmiştir. Yağların, oda sıcaklığında 12 ay süre boyunca renk ve oksidatif stabilite üzerine etkileri araştırılmıştır. Renk, serbest yağ asit içeriği ve peroksit değerlerindeki değişimler 2 aylık periyotlar halinde belirlenmiştir. Başlangıçta örneklerin renk değerleri 75,26-79,95 (ASTA değeri) aralığında bulunmuş ve ilave edilen yağ miktarı artıkça renk değeri düşmüştür. Bütün örneklerde renk kayıpları depolama süresinin artması ile artmış, bununla birlikte soya yağı ilaveli örneklerin renkleri daha stabil olmuştur. Kırmızı biberden ekstrakte edilen yağların serbest yağ asit içerikleri ve peroksit değerleri depolama süresinin artmasıyle önemli ölçüde artmıştır. Depolamanın sonunda susam yağı ilave edilmiş kırmızıbiber örneklerinin serbest yağ asit içerikleri, başlangıç de

Experimental and Numerical Investigation of the Plastic Region Behaviours of AA 1100 and AA 7075 Aluminium Alloys at Different Velocities and Energy Levels

This study investigated the Johnson-Cook (J-C) plastic region model of AA-1100 and AA-7075 series aluminium alloys. The tensile, three-point bending and low-velocity impact strengths at different velocities were investigated by keeping the equation constants and temperature constant for the J-C plastic region structural model. Tensile tests and three-point bending tests were performed at velocities of 1, 10, 20, and 40 s-1, respectively. Low-velocity impact tests of AA-1100 and AA-7075 alloys were performed at energy levels of 33,35; 66,71; 100; and 133,42 J, corresponding to velocities of 1,98(0.2 m), 2,80(0.4 m), 3,43(0.6 m) and 3,96(0.8 m) m/s, respectively. In addition, the materials' three-point bending, and low-velocity impact responses were also numerically investigated using a finite element model and compared with the experimental results. It is observed that the experimental and numerical results are in agreement with each other

TIM Systems: A Novel Approach for Determination of Bioaccessibility and Bioavailability of Food Components

The increasing rate of consciousness on innovative changes in foods has been increasingly grew the demand for the information about metabolism of these foods. Data about bioaccessibility and bioavailability of food components become more vital for both consumers and producers in the context of developing new healthier foods. Both nutrition and food researchers try to develop methods that allow user to obtain sufficient results of bioaccessibility and bioavailability of food compounds. Therefore, this study will summarize the TIM system, a novel system that mimics the human gastrointestinal system by all means, including working principles and studies performed in this system. In vivo and in vitro studies cannot be used as useful tool for measuring bioaccessibility and bioavailability of food components because of the physiological differences between human and animal. TIM studies were shown that this novel system could be easily used for the monitoring gastrointestinal movements of foods. In conclusion, TIM systems provide adequate data including digestibility, bioaccessibility and bioavailability of many different food products. By mimicking the GI tract, TIM system is a promising tool for the investigation of digestion, absorption components and health promoting aspects of foods