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Multi-scale investigation of active failure for various modes of wall movement

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Frontiers of Structural and Civil Engineering 2021年第4期15卷 961-979页

作者： ahmet Talha GEZGIN Behzad SOLTANBEIGI Adlen ALTUNBAS Ozer CINICIOGLU Department of Civil Engineering Bogazici UniversityIstanbul34342Turkey Estimating&Engineering Department Van Oord Dredging and Marine ContractorsRotterdam3063 NHThe Netherlands Department of Civil Engineering Medipol UniversityIstanbul34810Turkey

Retained backfill response to wall movement depends on factors that range from boundary conditions to the geometrical characteristic of individual ***,mechanical understanding of the problem warrants multi-scale analyses that investigate reciprocal relationships between macro and micro ***,this study attempts a multi-scale examination of failure evolution in cohesionless ***,the transition of retained backfills from at-rest condition to the active state is modeled using the discrete element method(DEM).DEM allows conducting virtual experiments,with which the variation of particle and boundary properties is ***,various modes of wall movement(translation and rotation)toward the active state are modeled using two different backfills with distinct particle shapes(spherical and nonspherical)under varying *** each model,cumulative rotations of single particles are tracked,and the results are used to analyze the evolution of shear bands and their geometric ***,dependencies of lateral pressure coefficients and coordination numbers,as respective macro and micro behavior indicators,on particle shape,boundary conditions,and surcharge levels are ***,contact force networks are visually determined,and their influences on pressure distribution and deformation mechanisms are discussed with reference to the associated modes of wall movement and particle shapes.

关键词： discrete-element modelling granular materials retaining walls particle shape arching

ASSERT:attack synthesis and separation with entropy redistribution towards predictive cyber defense

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Cybersecurity 2019年第1期2卷 253-270页

作者： ahmet Okutan Shanchieh Jay Yang Computer Engineering Rochester Institute of TechnologyRochesterNYUSA

The sophistication of cyberattacks penetrating into enterprise networks has called for predictive defense beyond intrusion detection,where different attack strategies can be analyzed and used to anticipate next malicious actions,especially the unusual ***,traditional predictive analytics or machine learning techniques that require training data of known attack strategies are not practical,given the scarcity of representative data and the evolving nature of *** paper describes the design and evaluation of a novel automated system,ASSERT,which continuously synthesizes and separates cyberattack behavior models to enable better prediction of future *** takes streaming malicious event evidences as inputs,abstracts them to edge-based behavior aggregates,and associates the edges to attack models,where each represents a unique and collective attack *** follows a dynamic Bayesian-based model generation approach to determine when a new attack behavior is present,and creates new attack models by maximizing a cluster validity *** generates empirical attack models by separating evidences and use the generated models to predict unseen future *** continuously evaluates the quality of the model separation and triggers a re-clustering process when *** the use of 2017 National Collegiate Penetration Testing Competition data,this work demonstrates the effectiveness of ASSERT in terms of the quality of the generated empirical models and the predictability of future actions using the models.

关键词： Cyber security Dynamic bayesian classifier Clustering KL divergence

Potential role of Müller cells in the pathogenesis of macropsia associated with epiretinal membrane:a hypothesis revisited

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International Journal of Ophthalmology(English edition) 2017年第11期10卷 1759-1767页

作者： ahmet Colakoglu Solmaz Balci Aka Department of Ophthalmology Acibadem University Schoolof MedicineIstanbul 34752Turkey Department of Ophthalmology Istanbul University CerrahpasaSchool of MedicineIstanbul 34098Turkey

Pathophysiological explanations for metamorphopsia associated with retinal pathologies generally focus on photoreceptor organization disruption. However, the retinal microarchitecture is complicated, and we hypothesize that other retinal cells may also be involved. Metamorphopsia has been widely studied in eyes with epiretinal membranes and we revisit the idea that Müller cell displacement causes retinal macropsia. A Pub Med query and related article search for the macula ultrastructure under normal and pathological conditions revealed an enormous amount of information, particularly ultrahigh definition optical coherence tomography and other retinal imaging modality studies. Findings of these imaging studies support our hypothesis that Müller cells, and not cone photoreceptors, are primarily responsible for macropsia in eyes with epiretinal membranes. More specifically, we conclude that displacement of Müller cell endfeet, and not photoreceptor cones, is a more likely the explanation for retinal macropsia associated with epiretinal membranes.

关键词： macropsia metamorphopsia epiretinal membrane Müller cells

Circulating cancer stem cells:the importance to select

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Chinese Journal of Cancer Research 2015年第5期27卷 437-449页

作者： Ming-Hsin Yang ahmet Imrali Christopher Heeschen Centre for Stem Cells in Cancer & Ageing Barts Cancer InstituteQueen Mary University of London Division of Urology Department of SurgeryTri-Service General HospitalNational Defense Medical Center Stem Cells & Cancer Group Molecular Pathology ProgrammeSpanish National Cancer Research Centre(CNIO)

It has been demonstrated that even localized tumors withottt chnically apparent metastasis give rise to circulating tumor cells （CTCs）. A growing number of technically diverse platforms are being developed for detecting/isolating CTCs in the circulating blood. Despite the technical challenges of isolating rare CTCs from blood, recent studies have already shown the predictive value of CTCs enumeration. Thus, it is becoming increasingly accepted that CTC numbers are linked to patients＇ outcome and may also be used to monitor treatment response and disease relapse, respectively. Further CTCs provide a non-invasive source for tumor material, ＇liquid biopsy＇, which is particularly important for patients, where no biopsy material can be obtained or where serial biopsies of the tumor, e.g., following treatment, are practically impossible. On the other hand the molecular and biological characterization of CTCs has still remained at a rather experimental stage. Future studies are necessary to define CTC heterogeneity to establish the crucial role of circulating cancer stem cells for driving metastasis, which represent a distinct subpopulation of CTCs that bear metastasis-initiating capabilities based on their sternness properties and invasiveness and thus are critical for the patients＇ clinical outcome. As compared to non-tumorigenic/metastatic bulk CTCs, circulating cancer stem cells may not only be capable of evading from the primary tumor, but also escape from immune surveillance, survive in the circulating blood and subsequently form metastases in distant organs. Thus, circulating cancer stem cells represent a subset of exclusively tumorigenic cancer stem cells characterized by their invasive characteristics and are potential therapeutic targets for preventing disease progression. To date, only a few original reports and reviews have been published focusing on circulating cancer stem cells. This review discusses the potential importance of isolating and characterizing th

关键词： Cancer stem cells circulating tumor cells (CTCs) drug resistance

Depth perception differences between hemispheres,genders,and eye dominance A study on evoked potential

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Neural Regeneration Research 2009年第11期4卷 947-950页

作者： ahmet Akay Gürbüz elebi Ege University Medical School Department of Biophysics

BACKGROUND： Certain neural functions, such as peripheral reflexes, differ between genders, while higher brain functions, such as language, are asymmetrically distributed between the two hemispheres. The question remains as to whether depth perception differs between hemispheric laterality and genders, and whether it is affected by eye dominance. OBJECTIVE： To determine whether depth perception is influenced by factors such as gender, eye dominance, and hemispheric lateralization by recording evoked potential associated with depth perception. DESIGN, TIME AND SETTING： A contrast observation based on neuroelectrophysiology was performed at the Department of Biophysics of Ege University Medical School between June 2006 and April 2007. PARTICIPANTS： A total of 34 subjects, 19 females and 15 males, were included in the study with a mean age of （31.0 ± 6.9） years. All subjects were free of neurological or psychological disorders, or problems such as strabismus or vision correction. METHODS： Random-dot stereograms were used to elicit brain activity. A specially designed signal acquisition system employing two computers was used to record evoked potentials from both hemispheres via two pairs of scalp electrodes placed over the occipitotemporal areas of both hemispheres at symmetrical locations. MAIN OUTCOME MEASURES： Negative potential with a mean latency of （211.21 ±25.55） ms and a mean amplitude of （6.05 ± 1.53） pV was recorded from both occipitotemporal areas in 30 out of 34 participants. This was termed ＂Nd＂ and represented the evoked potential associated with depth perception. RESULTS： There were no significant differences in Nd amplitude or latency between the two hemispheres, the two eyes, or genders （P 〉 0.05）. CONCLUSION： The evoked potential associated with depth perception was not influenced by gender, hemisphere, or eye dominance.

关键词： random-dot stereogram depth perception, stereovision eye dominance hemisphere lateralization: sex difference

Synthesis and Characterization of New Macrocyclic Cu（Ⅱ） Complexes from Various Diamines, Copper（Ⅱ） Nitrate and 1,4-Bis（2-formylphenoxy）butane

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Chinese Journal of Chemistry 2007年第10期25卷 1547-1550页

作者： ILHAN, Salih TEMEL, Hamdi KILIC, ahmet Chemistry Department Faculty of Education Dicle University Diyarbakir 21010 Turkey Chemistry Department Faculty of Art and Science Harran University Sanhurfa 63100 Turkey

Six new macrocyclic complexes were synthesized by a template reaction of 1,4-bis（2-formylphenoxy）butane with diamines and Cu（NO3）2·3H2O and their structures were proposed on the basis of elemental analysis, FT-IR, UV-Vis, magnetic susceptibility measurements, molar conductivity measurements and mass spectra. The metal to ligand molar ratios of the Cu（Ⅱ） complexes were found to be 1 ： 1. The Cu（Ⅱ） complexes are 1 ： 2 electrolytes as shown by their molar conductivities （∧m） in DMF at 10^-3 mol·L^-1. Due to the existence of free ions the Cu（Ⅱ） complexes are electrically conductive. Their configurations were proposed to be probably distorted octahedral.

关键词： macrocyclic Schiff base complex 1,4-bis(2-formylphenoxy)butane diamine copper(Ⅱ) complex

Analysis of temporal changes in land cover and landscape metrics of a managed forest in the west Black Sea region of northern Turkey: 1970–2010

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Journal of Forestry Research 2018年第1期29卷 139-150页

作者： Hayati Zengin ahmet Salih Degermenci Pete Bettinger Department of Forest Management and Planning Faculty of Forestry Duzce University Warnell School of Forestry and Natural Resources University of Georgia

Forest structure changes continuously by natural and anthropogenic effects. Because the level of goods and services provided by forest ecosystems are related to this structure, some attributes have to be controlled while they are being managed. In this paper we describe the long-term temporal changes in land area and landscape metrics related to different land uses of a managed forest in Turkey. The study was carried out for the Daday Forest Planning Unit located in the west Black Sea region of northern Turkey. The total area is 16,813 ha and besides wood production, it is managed for erosion control, public health, aesthetics, and recreation. Stand type maps that were constructed in 1970,1989, 1999, and 2010 were used in this analysis. Transition matrixes that illustrate area changes among cover types and temporal changes on some landscape metrics were obtained using Geographic Information Systems. Stands were separated into small patches, and thus the number of patches increased nearly two-fold between 1970 and 2010. The total forest edge increased and through the associated fragmentation, the amount of core forest area decreased at the landscape scale. Landscape metrics were applied to digitized versions of historical maps to assess how forest area changed. Human use of the land has changed, forest management practices have evolved, and these along with natural forest growth have contributed to interesting changes in landscape character.

关键词： Landscape metrics Land cover change Temporal change Turkey

Frequency and voltage-dependent electrical and dielectric properties of Al/Co-doped PVA/p-Si structures at room temperature

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Chinese Physics B 2014年第4期23卷 545-550页

作者： Ibrahim Ycedag ahmet Kaya Semsettin Altindal Ibrahim Uslu Department of Computer Engineering Technology Faculty Duzce University Department of Opticianry Vocationel School of Medical Sciences Turgut Ozal University Department of Physics Faculty of Science and Arts Gazi University Department of Chemistry Faculty of Science and Arts Gazi University

In order to investigate of cobalt-doped interracial polyvinyl alcohol （PVA） layer and interface trap （Dit） effects, A1/p- Si Schottky barrier diodes （SBDs） are fabricated, and their electrical and dielectric properties are investigated at room temperature. The forward and reverse admittance measurements are carded out in the frequency and voltage ranges of 30 kHz-300 kHz and -5 V-6 V, respectively. C-V or er-V plots exhibit two distinct peaks corresponding to inversion and accumulation regions. The first peak is attributed to the existence of Dit, the other to the series resistance （Rs）, and interfacial layer. Both the real and imaginary parts of dielectric constant （er and err） and electric modulus （Mr and Mrr）, loss tangent （tan~）, and AC electrical conductivity （aac） are investigated, each as a function of frequency and applied bias voltage. Each of the M~ versus V and Mrr versus V plots shows a peak and the magnitude of peak increases with the increasing of frequency. Especially due to the Dit and interfacial PVA layer, both capacitance （C） and conductance （G/w） values are strongly affected, which consequently contributes to deviation from both the electrical and dielectric properties of A1/Co-doped PVA/p-Si （MPS） type SBD. In addition, the voltage-dependent profile of Dit is obtained from the low-high frequency capacitance （CLF-CHF） method.

关键词： Al/Co-PVA/p-Si (MPS) electrical and dielectric properties AC electrical conductivity frequencyand voltage dependence

Illumination and Voltage Dependence of Electrical Characteristics of Au/0.03 Graphene-Doped PVA/n-Si Structures via Capacitance/Conductance-Voltage Measurements

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Chinese Physics Letters 2015年第11期32卷 92-96页

作者： SAHAR Alialy ahmet Kaya I Uslua EMSETTIN Altmdal physics Department Faculty of Sciences Gazi University Ankara 06500 Turkey Opticianry Department Vocat Sch IVied Sci 7hrkey Turgut Ozal University Ankara 78050 Turkey Department of Chemistry Education Faculty of Education GazJ University Ankara 06500 Turkey

Au/n-Si （MS） structures with a high dielectric interlayer （0.03 graphene-doped PVA） are fabricated to investigate the illumination and voltage effects on electrical and dielectric properties by using capacitance-voltage （C-V） and conductance-voltage （G/w-V） measurements at room temperature and at 1 MHz. Some of the main electrical parameters such as concentration of doping atoms （ND）, barrier height （ ФB（ C - V））, depletion layer width （WD） and series resistance （Rs） show fairly large illumination dispersion. The voltage-dependent profile of surface states （Nss） and resistance of the structure （Ri ） are also obtained by using the dark-illumination capacitance （Cdark- Cm） and Nicollian-Brews methods, respectively, For a clear observation of changes in electrical parameters with illumination, the values of ND, WD, ФB（O- V） and Rs are drawn as a function of illumination intensity. The values of ND and WD change almost linearly with illumination intensity. On the other hand, Rs decreases almost exponentially with increasing illumination intensity whereas ФB（C - V） increases. The experimental results suggest that the use of a high dielectric interlayer （0.03 graphene-doped PVA） considerably passivates or reduces the magnitude of the surface states. The large change or dispersion in main electrical parameters can be attributed to generation of electron-hole pairs in the junction under illumination and to a good light absorption. All of these experimental results confirm that the fabricated Au/0.03 graphene-doped PVA/n-Si structure can be used as a photodiode or a capacitor in optoelectronic applications.

关键词： Si PVA Illumination and Voltage Dependence of Electrical Characteristics of Au/0.03 Graphene-Doped PVA/n-Si Structures via Capacitance/Conductance-Voltage Measurements