47 research outputs found

    How the consequences of the COVID-19 pandemic affected housing sector? Empirical evidence from Turkey

    Get PDF
    PurposeThis study aims to analyze the relationship between the consequences of the pandemic and the housing sector with econometric tests that allow for structural breaks.Design/methodology/approachStudy data were collected weekly between March 9, 2020, and February 4, 2022, and analyzed for Turkey. In the model of the study, housing loans were used as a housing market indicator, and the number of new deaths and new cases were used as data related to the pandemic. The exchange rate, which affects the use of housing loans, was added to the model as a control variable. This study was analyzed to examine the relationship between the pandemic and the housing sector, time series analysis techniques that allow structural breaks were used.FindingsBased on the result of the analyses, it was concluded that there is a long-run relationship between the pandemic stages and housing markets along with structural breaks. As a result of the time-varying causality test developed to determine the causality relationship between the variables and its direction, a bidirectional causality relationship was identified between all variables at certain dates.Research limitations/implicationsStudy data were collected weekly between March 9, 2020, and February 4, 2022, and analyzed in the case of Turkey.Practical implicationsBased on results of the study, it is recommended that policy makers and market actors take into account extraordinary situations such as pandemics and create a budget allocation that is always ready to use for this purpose.Originality/valueThe empirical examination of the relationship between the pandemic and the housing sector in Turkey provides origina

    Non-invasive diagnostic tests for Helicobacter pylori infection

    Get PDF
    BACKGROUND: Helicobacter pylori (H pylori) infection has been implicated in a number of malignancies and non-malignant conditions including peptic ulcers, non-ulcer dyspepsia, recurrent peptic ulcer bleeding, unexplained iron deficiency anaemia, idiopathic thrombocytopaenia purpura, and colorectal adenomas. The confirmatory diagnosis of H pylori is by endoscopic biopsy, followed by histopathological examination using haemotoxylin and eosin (H & E) stain or special stains such as Giemsa stain and Warthin-Starry stain. Special stains are more accurate than H & E stain. There is significant uncertainty about the diagnostic accuracy of non-invasive tests for diagnosis of H pylori. OBJECTIVES: To compare the diagnostic accuracy of urea breath test, serology, and stool antigen test, used alone or in combination, for diagnosis of H pylori infection in symptomatic and asymptomatic people, so that eradication therapy for H pylori can be started. SEARCH METHODS: We searched MEDLINE, Embase, the Science Citation Index and the National Institute for Health Research Health Technology Assessment Database on 4 March 2016. We screened references in the included studies to identify additional studies. We also conducted citation searches of relevant studies, most recently on 4 December 2016. We did not restrict studies by language or publication status, or whether data were collected prospectively or retrospectively. SELECTION CRITERIA: We included diagnostic accuracy studies that evaluated at least one of the index tests (urea breath test using isotopes such as13C or14C, serology and stool antigen test) against the reference standard (histopathological examination using H & E stain, special stains or immunohistochemical stain) in people suspected of having H pylori infection. DATA COLLECTION AND ANALYSIS: Two review authors independently screened the references to identify relevant studies and independently extracted data. We assessed the methodological quality of studies using the QUADAS-2 tool. We performed meta-analysis by using the hierarchical summary receiver operating characteristic (HSROC) model to estimate and compare SROC curves. Where appropriate, we used bivariate or univariate logistic regression models to estimate summary sensitivities and specificities. MAIN RESULTS: We included 101 studies involving 11,003 participants, of which 5839 participants (53.1%) had H pylori infection. The prevalence of H pylori infection in the studies ranged from 15.2% to 94.7%, with a median prevalence of 53.7% (interquartile range 42.0% to 66.5%). Most of the studies (57%) included participants with dyspepsia and 53 studies excluded participants who recently had proton pump inhibitors or antibiotics.There was at least an unclear risk of bias or unclear applicability concern for each study.Of the 101 studies, 15 compared the accuracy of two index tests and two studies compared the accuracy of three index tests. Thirty-four studies (4242 participants) evaluated serology; 29 studies (2988 participants) evaluated stool antigen test; 34 studies (3139 participants) evaluated urea breath test-13C; 21 studies (1810 participants) evaluated urea breath test-14C; and two studies (127 participants) evaluated urea breath test but did not report the isotope used. The thresholds used to define test positivity and the staining techniques used for histopathological examination (reference standard) varied between studies. Due to sparse data for each threshold reported, it was not possible to identify the best threshold for each test.Using data from 99 studies in an indirect test comparison, there was statistical evidence of a difference in diagnostic accuracy between urea breath test-13C, urea breath test-14C, serology and stool antigen test (P = 0.024). The diagnostic odds ratios for urea breath test-13C, urea breath test-14C, serology, and stool antigen test were 153 (95% confidence interval (CI) 73.7 to 316), 105 (95% CI 74.0 to 150), 47.4 (95% CI 25.5 to 88.1) and 45.1 (95% CI 24.2 to 84.1). The sensitivity (95% CI) estimated at a fixed specificity of 0.90 (median from studies across the four tests), was 0.94 (95% CI 0.89 to 0.97) for urea breath test-13C, 0.92 (95% CI 0.89 to 0.94) for urea breath test-14C, 0.84 (95% CI 0.74 to 0.91) for serology, and 0.83 (95% CI 0.73 to 0.90) for stool antigen test. This implies that on average, given a specificity of 0.90 and prevalence of 53.7% (median specificity and prevalence in the studies), out of 1000 people tested for H pylori infection, there will be 46 false positives (people without H pylori infection who will be diagnosed as having H pylori infection). In this hypothetical cohort, urea breath test-13C, urea breath test-14C, serology, and stool antigen test will give 30 (95% CI 15 to 58), 42 (95% CI 30 to 58), 86 (95% CI 50 to 140), and 89 (95% CI 52 to 146) false negatives respectively (people with H pylori infection for whom the diagnosis of H pylori will be missed).Direct comparisons were based on few head-to-head studies. The ratios of diagnostic odds ratios (DORs) were 0.68 (95% CI 0.12 to 3.70; P = 0.56) for urea breath test-13C versus serology (seven studies), and 0.88 (95% CI 0.14 to 5.56; P = 0.84) for urea breath test-13C versus stool antigen test (seven studies). The 95% CIs of these estimates overlap with those of the ratios of DORs from the indirect comparison. Data were limited or unavailable for meta-analysis of other direct comparisons. AUTHORS' CONCLUSIONS: In people without a history of gastrectomy and those who have not recently had antibiotics or proton ,pump inhibitors, urea breath tests had high diagnostic accuracy while serology and stool antigen tests were less accurate for diagnosis of Helicobacter pylori infection.This is based on an indirect test comparison (with potential for bias due to confounding), as evidence from direct comparisons was limited or unavailable. The thresholds used for these tests were highly variable and we were unable to identify specific thresholds that might be useful in clinical practice.We need further comparative studies of high methodological quality to obtain more reliable evidence of relative accuracy between the tests. Such studies should be conducted prospectively in a representative spectrum of participants and clearly reported to ensure low risk of bias. Most importantly, studies should prespecify and clearly report thresholds used, and should avoid inappropriate exclusions

    Homocysteine Levels in Parkinson’s Disease: Is Entacapone Effective?

    No full text
    Plasma homocysteine (Hcy) levels may increase in levodopa-treated patients with Parkinson’s disease (PD) as a consequence of levodopa methylation via catechol-O-methyltransferase (COMT). Results from previous studies that assessed the effect of COMT inhibitors on levodopa-induced hyperhomocysteinemia are conflicting. We aimed to evaluate the effects of levodopa and entacapone on plasma Hcy levels. A hundred PD patients were enrolled to the study and divided into three treatment groups (group I: levodopa and/or dopamine agonists; group II: levodopa, entacapone, and/or a dopamine agonist; and group III: dopamine agonist alone). We measured the serum B12, folic acid, and Hcy levels in all patients. There were no statistically significant differences between groups in terms of modified Hoehn and Yahr stages, Unified Parkinson’s Disease Rating Scale II/III, Standardized Mini-Mental Test scores, and serum vitamin B12 and folic acid levels. Plasma median Hcy levels were found above the normal laboratory values in groups I and II, but they were normal in group III. However, there was no statistically significant difference in plasma Hcy levels between groups. Our results showed that levodopa treatment may cause a slight increase in the Hcy levels in PD compared with dopamine agonists and that COMT inhibitors may not have a significant effect on preventing hyperhomocysteinemia

    An improved sensorless DTC-SVM for three-level inverter-fed permanent magnet synchronous motor drive

    No full text
    Okumus, H. Ibrahim/0000-0002-4303-5057; Usta, Mehmet Ali/0000-0002-2792-0769WOS: 000451931800033A speed-sensorless control strategy is investigated in a wide speed range based on extended Kalman filter (EKF) and direct torque control with space vector modulation (DTC-SVM) for three-level cascaded H-bridge inverter-fed permanent magnet synchronous motor drives. the implementation of conventional SVM technique to the multilevel inverters is considerably complicated and leads to high computational burden. A three-level SVM technique simplified on the basis of two-level voltage vector diagram is proposed to reduce this computational complexity, and in addition, to satisfy some requirements for the safe operation of the inverter such as smooth commutation and minimum number of switching. the estimations of rotor position and speed are achieved using an EKF without high-frequency signal injection, especially at very low and zero speeds. the load torque is also estimated simultaneously to account for the mechanical frictions at steady state to improve the estimation performance. Furthermore, the flux trajectory control based on maximum torque per ampere algorithm is implemented to ensure maximal efficiency for constant torque region. the feasibility and effectiveness of the proposed drive system is tested under different operating conditions and verified by the simulation results.TUBITAKTurkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK)First author is supported by TUBITAK with 2214-A Doctorate Research Scholarship Programme. the authors would like to thank TUBITAK

    The Effect of Hyperhomocysteinemia on Motor Symptoms, Cognitive Status, and Vascular Risk in Patients with Parkinson’s Disease

    No full text
    Factors related with hyperhomocysteinemia (HHcy) and the impact of HHcy in Parkinson’s disease (PD) are not well understood. We investigated the factors associated with increased levels of homocysteine (Hcy) and the relationship between HHcy and motor symptoms, cognitive status, and vascular risk in patients with Parkinson’s disease. Among 60 patients (29 males, 48.3%) with PD, the stage of the disease, the severity of clinical symptoms, and the patients’ cognitive status were measured using a modified Hoehn and Yahr Staging Scale (mHY), Unified Parkinson’s Disease Rating Scale (UPDRS) II and III, and Mini-Mental State Examination (MMSE), respectively. Patients were also noted for having dyskinesia and hallucinations. Serum vitamin B12, folic acid, and plasma Hcy ​​levels were measured. Furthermore, the presence of vascular risk factors was recorded. Finally, we investigated carotid artery intima-media thickening and stenosis using colour Doppler ultrasonography as well as the presence of ischemic lesions using brain imaging techniques. Plasma Hcy ​​levels were higher with advanced age and in males. In addition, there was an inverse relationship between Hcy ​​and vitamin B12 levels. There was no correlation between HHcy and the stage of the disease, severity of motor symptoms, cognitive status as assessed by the MMSE, vascular risk factors, carotid artery atherosclerotic findings, and ischemic brain lesions. Plasma Hcy levels may rise due to several factors in PD. However, the resulting HHcy has no significant effect on the clinical picture in terms of motor features, cognitive status, and vascular diseases

    Graft materials in Peyronie's disease surgery: A comprehensive review

    No full text
    Objective. To discuss the currently used graft materials in Peyronie's surgery

    Metallo and metal free phthalocyanines bearing (4-(1(4-phenoxyphenyl)-1-phenylethyl)phenol substituents: Synthesis, characterization, aggregation behavior, electronic, antioxidant and antibacterial properties

    No full text
    WOS: 000341469300026As starting material the phthalonitrile derivative bearing (4-(1(4-phenoxyphenyl)-1-phenylethyl)phenol substituents at peripheral position was prepared by a nucleophilic displacement reaction. Cyclotetramerization of 4-(4-(1-(4-hydroxyyphenyl)-1-phenylethyl)phenoxy)phthalonitrile derivative in the presence of corresponding metal salts gave the new metallophthalocyanines. Metal free phthalocyanine was obtained from the reaction of 4-(4-(1-(4-hydroxyyphenyl)-1-phenylethyl)phenoxy)phthalonitrile units. The novel compounds have been characterized by using various spectroscopic data. The aggregation investigations carried out in different concentrations indicate that 4-(4-(1-(4-hydroxyyphenyl)-1-phenylethyl)phenoxy)phthalocyanine compounds do not have any aggregation behavior for the concentration range of 10(-4)-10(-5) M in tetrahydrofuran. The antioxidant activities of novel compounds were analyzed through radical scavenging ability of 1,1-dipheny1-2-picrylhydrazyl, chelating ability to ferrous ions and reducing power. In addition to these, the antibacterial activities of compounds were investigated. Moreover, the ground-state geometries of the complexes were optimized using B3LYP/6-31G(d,p) level of density functional theory in order to predict the three-dimensional geometries and electronic structure. (C) 2014 Elsevier B.V. All rights reserved

    Retrograde Intrarenal Surgery for Complex Stones in a Toddler with Congenital Renal Anomalies: Technical Details

    No full text
    We report herein the management of a challenging case due to anatomic and stone-related complications in a 37-month-old Caucasian toddler with megacalycosis and complex stone in the left kidney and duplicated ureter on the right side

    Changes in the blink reflex during migraine with aura and the inter-attack period

    No full text
    Introduction: This study aimed to investigate the possible excitability changes in the trigeminovascular system based on blink reflex (BR) in patients experiencing migraine and to compare migraine aura attacks and attack-free period. Materials and Methods: A total of 56 patients diagnosed with migraine headache with aura and 20 healthy individuals without migraine were evaluated electrophysiologically using the BR test. The BR test was repeated twice in patients with migraines during attacks with aura and attack-free period. Results: During the migraine attack with aura, R1 latencies were shorter, and R2 latencies were longer than in the interictal period. Likewise, R1 latencies were shorter, and R2 latencies were longer, in the interictal period compared to normal values obtained in the control group. Conclusion: The detected BR abnormalities have been thought to be able to reflect migraine-related dysfunction in the brainstem and trigeminovascular connections. Significance: It has been concluded that the detected BR abnormalities might reflect migraine-related dysfunction in the brainstem and trigeminovascular connections, indicating increased neuronal excitability in migraine
    corecore