The influence of particle shape on bedload transport in coarse-bed river channels

This thesis investigates the influence of bed material shape on sediment transport in gravel-bed rivers. The approach involves a combined series of field and laboratory experiments. Magnetic tracing experiments were carried out at three experimental sites in two Pennine gravel-bed streams. The specific aim of these experiments was to quantify the selective transport of different shapes of coarse river gravel and determine their spatial sorting within a natural stream channel. A total of 900 tracers in three size groups (32- 64 mm, 64-128 mm and greater than 128 mm) and four shape classes (spheres, blades, rod and discs) were prepared for each of the three sites. In die laboratory, tilting table experiments were carried out to clarify the mechanistic behaviour of different particle shapes, sizes and orientations on a variety of artificial and naturally formed bed roughnesses. Using strobe-light photography visualization experiments were undertaken with natural and artificially-moulded gravel-size particles of differing shape, size and weight in order to investigate the influence of shape on settling, grain impact, initial motion and transport paths of gravel-size particles. Results of the magnetic tracing experiments showed that there was both size and shape selectivity in bedload transport. Preferential movement occurred in die small and medium particle size classes with tracers concentrated along the channel thalweg. Sphere-shaped particles were transported the greatest distance and in greatest numbers. Rods also moved preferentially, while discs showed a lesser degree of transport and blades hardly moved at all. Results from the tilting table experiments highlight the importance of roundness as well as particle form and particle orientation in continuing thresholds of entertainment. In terms of size, friction angle was found to depend on the ratio of the diameter of the test particle to be moved to that it rests upon (d/D). Shape and orientation were found to be important parameters influencing friction angles. On a given bed roughness and for a constant size non-spherical test particles showed greater friction angles than spherical ones. A very clear difference was found in friction angle distibutions between sphere, transverse rod and other flat-shaped particles, namely, blades with parallel and transverse orientations, disc, and rod with parallel orientations. Visualisation experiments indicated that shape is an important particle characteristic that has a significant effect on settling rates and also the mode of near bed transport. These effects increase with greater particle sizes. The departure of a particle from a sphere leads to a decrease in its settling velocity, Experiments, across a range of test sizes showed that when compared to a sphere of equivalent weight and density, sphere and rod-shaped particles tend to settle the fastest and move by rolling. Discs and blades showed slower settling rates and, in most instances, moved by sliding. Experiments carried out with irregularly-shaped, natural particles show greater variability in settling behaviour and irregular patterns of motion. For every size group, sphere and rod shaped particles have lower critical angles of initial motion flian blade and disc-shapes. Regardless of shape, greater bed roughness, or decreasing particle size results in an increase in the critical angle for motion

An Extraordinary Cause of the Sucking Difficulty: Ecthyma Gangrenosum

Ecthyma gangrenosum is a cutaneous lesion often associated with pseudomonas aeruginosa bacteremia, even though it may develop without bacteremia and may originate from other bacterial and fungal organisms. Pseudomonas aeruginosa bacteremia or sepsis, which mainly affects immunocompromised patients, frequently occurs in hospitals. This lesion typically occurs on the extremities and gluteal and perineal regions. In this report we present a case of ecthyma gangrenosum in a premature newborn occurring secondary to pseudomonas sepsis causing sucking dysfunction due to tissue loss in the lip, soft palate, and tongue

The effects of iron deficiency anemia on p wave duration and dispersion

OBJECTIVES: The association between P wave dispersion and iron deficiency anemia has not been documented in the literature. In this study, we evaluated P wave dispersion in patients with iron deficiency anemia and the possible relationships between P wave dispersion and other echocardiographic parameters. INTRODUCTION: The iron status of an individual may play an important role in cardiovascular health. Anemia is an independent risk factor for adverse cardiovascular outcomes. P wave dispersion is a simple electrocardiographic marker that has a predictive value for the development of atrial fibrillation. Apart from cardiovascular diseases, several conditions, such as seasonal variation, alcohol intake and caffeine ingestion, have been demonstrated to affect P wave dispersion. METHODS: The study included 97 patients who had iron deficiency anemia and 50 healthy subjects. The cases were evaluated with a clinical examination and diagnostic tests that included 12-lead electrocardiography and transthoracic echocardiography. RESULTS: Compared to the control group, patients with iron deficiency anemia showed significantly longer maximum P wave duration (Pmax) (91.1±18.0 vs. 85.8±6.7 msec, p=0.054), P wave dispersion (PWD) (48.1±7.7 vs. 40.9±5.6 msec,

Structurally controlled landscape evolution in Kula badlands, Western Turkey

Badlands are extensively eroded landscapes consisting of weakly consolidated deposits within highly dense drainage systems. Their controlling and shaping factors can differ in relation to various internal and external conditions and processes that are not always well understood. This study focuses on the development of a badland landscape affecting Miocene and Quaternary sand-clay sediments in the extensional tectonic regime of Western Turkey with a multidisciplinary approach. The area between Kula and Selendi towns exhibits a badland topography with extensively eroded surface features, deepened gullies within poorly consolidated, sand clay-sized sediments. The results of structural field mapping and morphometric analyses using a 5 m resolution DEM to study the role of structural control in the development of badlands are presented in this study. Field data analysis supported by the quantitative assessment of longitudinal gully profiles illustrates the role of pre-existing structures as faults, their orientation and geometry in net erosion-sedimentation and the development of deepened gully networks. Representative illustrations, field photographs and block diagrams are presented to show the relationship between the rock structure and badland landscape. The connection between the extensional tectonics, erosional dynamics and geomorphology point to a structurally-controlled landscape in the Kula badlands in Western Turkey

Trace Elements, Heavy Metals and Vitamin Levels in Patients with Coronary Artery Disease

Aim: In the present study, we aimed to assess serum concentrations of zinc (Zn), copper (Cu), iron (Fe), cadmium (Cd), lead (Pb), manganese (Mn), vitamins A (retinol), D (cholecalciferol) and E (α-tocopherol) in patients with coronary artery disease (CAD) and to compare with healthy controls

The role of hepcidin and its related genes (BMP6, GDF-15, and HJV) in rats exposed to ischemia and reperfusion

Background/aim: To determine the roles of hepcidin and its related genes in a renal ischemia/reperfusion model. Materials and methods: A total of 20 Wistar albino rats were equally divided into 2 groups: Group I was the control group and Group II was the ischemia and reperfusion (I/R) group (60 min of ischemia + 48 h of reperfusion). I/R was performed on the left kidneys of these rats and then the I/R-treated kidneys were removed. The levels of serum biochemical markers were evaluated after renal I/R. The expression levels of hepcidin-linked genes [growth differentiation factor 15 (GDF-15), bone morphogenetic protein 6 (BMP6), and hemojuvelin (HJV)] were also measured by RT-PCR technique. In addition, the tissues were evaluated histopathologically. Results: No significant association was found between renal dysfunction and I/R when compared to biochemical parameters (P > 0.05). However, differences in platelet values were statistically significant (P < 0.05). Expression levels of GDF-15, BMP6, and HJV genes increased, but this increase was not statistically significant. In addition, histopathological evaluation was performed using hematoxylin and eosin stain. This showed a significant relationship between the control group and I/R group for ischemic and nonischemic kidney scoring. Conclusion: Hepcidin and BMP6, HJV, and GDF-15 should be taken into account when investigating the process of I/R.Background/aim: To determine the roles of hepcidin and its related genes in a renal ischemia/reperfusion model. Materials and methods: A total of 20 Wistar albino rats were equally divided into 2 groups: Group I was the control group and Group II was the ischemia and reperfusion (I/R) group (60 min of ischemia + 48 h of reperfusion). I/R was performed on the left kidneys of these rats and then the I/R-treated kidneys were removed. The levels of serum biochemical markers were evaluated after renal I/R. The expression levels of hepcidin-linked genes [growth differentiation factor 15 (GDF-15), bone morphogenetic protein 6 (BMP6), and hemojuvelin (HJV)] were also measured by RT-PCR technique. In addition, the tissues were evaluated histopathologically. Results: No significant association was found between renal dysfunction and I/R when compared to biochemical parameters (P > 0.05). However, differences in platelet values were statistically significant (P < 0.05). Expression levels of GDF-15, BMP6, and HJV genes increased, but this increase was not statistically significant. In addition, histopathological evaluation was performed using hematoxylin and eosin stain. This showed a significant relationship between the control group and I/R group for ischemic and nonischemic kidney scoring. Conclusion: Hepcidin and BMP6, HJV, and GDF-15 should be taken into account when investigating the process of I/R

Evaluation of the safety of intracameral trypan blue injection on corneal tissue using oxidative stress parameters and apoptotic activity: an experimental study

Purpose: The present experimental study aimed to investigate the effects of intracameral trypan blue (TB) on oxidative stress parameters and apoptosis in corneal tissue. Methods: Thirty rats were randomly assigned to three groups of 10 rats each: the sham group (Group 1); control group (Group 2); and treatment group (Group 3). The control group was administered 0.01 cc of balanced salt solution. The treatment group was administered 0.006 mg/0.01 cc of TB. The total antioxidant status (TAS) and total oxidant status (TOS) in corneal tissue and blood were measured and the oxidative stress index (OSI) was calculated. Finally, corneal tissue histopathology was evaluated using staining for caspase-3 and -8, and apoptotic activity was examined. Results: The TAS, TOS and OSI levels in the blood samples were not significantly different (p>0.05 for all). Compared with the sham and control groups, the TOS and OSI levels in corneal tissue were significantly different in the treatment group (p<0.05 for all). No significant difference was observed between the sham group and the control group (p>0.05). Immunohistochemical staining for caspase-3 and caspase-8 demonstrated higher apoptotic activity in the TB group than in the sham and control groups. Conclusion: The present study showed that intracameral TB injection is safe systematically but may be toxic to corneal tissue, as demonstrated using oxidative stress parameters and histopathological evaluation

A nationwide multicentre study in Turkey for establishing reference intervals of haematological parameters with novel use of a panel of whole blood

IntroductionA nationwide multicentre study was conducted to establish well-defined reference intervals (RIs) of haematological parameters for the Turkish population in consideration of sources of variation in reference values (RVs). Materials and methodsK2-EDTA whole blood samples (total of 3363) were collected from 12 laboratories. Sera were also collected for measurements of iron, UIBC, TIBC, and ferritin for use in the latent abnormal values exclusion (LAVE) method. The blood samples were analysed within 2 hours in each laboratory using Cell Dyn and Ruby (Abbott), LH780 (Beckman Coulter), or XT-2000i (Sysmex). A panel of freshly prepared blood from 40 healthy volunteers was measured in common to assess any analyser-dependent bias in the measurements. The SD ratio (SDR) based on ANOVA was used to judge the need for partitioning RVs. RIs were computed by the parametric method with/without applying the LAVE method. ResultsAnalyser-dependent bias was found for basophils (Bas), MCHC, RDW and MPV from the panel test results and thus those RIs were derived for each manufacturer. RIs were determined from all volunteers’ results for WBC, neutrophils, lymphocytes, monocytes, eosinophils, MCV, MCH and platelets. Gender-specific RIs were required for RBC, haemoglobin, haematocrit, iron, UIBC and ferritin. Region-specific RIs were required for RBC, haemoglobin, haematocrit, UIBC, and TIBC. ConclusionsWith the novel use of a freshly prepared blood panel, manufacturer-specific RIs’ were derived for Bas, Bas%, MCHC, RDW and MPV. Regional differences in RIs were observed among the 7 regions of Turkey, which may be attributed to nutritional or environmental factors, including altitude

Real-world efficacy and safety of Ledipasvir plus Sofosbuvir and Ombitasvir/Paritaprevir/Ritonavir +/- Dasabuvir combination therapies for chronic hepatitis C: A Turkish experience

Background/Aims: This study aimed to evaluate the real-life efficacy and tolerability of direct-acting antiviral treatments for patients with chronic hepatitis C (CHC) with/without cirrhosis in the Turkish population.Material and Methods: A total of 4,352 patients with CHC from 36 different institutions in Turkey were enrolled. They received ledipasvir (LDV) and sofosbuvir (SOF)+/- ribavirin (RBV) ombitasvir/paritaprevir/ritonavir +/- dasabuvir (PrOD)+/- RBV for 12 or 24 weeks. Sustained virologic response (SVR) rates, factors affecting SVR, safety profile, and hepatocellular cancer (HCC) occurrence were analyzed.Results: SVR12 was achieved in 92.8% of the patients (4,040/4,352) according to intention-to-treat and in 98.3% of the patients (4,040/4,108) according to per-protocol analysis. The SVR12 rates were similar between the treatment regimens (97.2%-100%) and genotypes (95.6%-100%). Patients achieving SVR showed a significant decrease in the mean serum alanine transaminase (ALT) levels (50.90 +/- 54.60 U/L to 17.00 +/- 14.50 U/L) and model for end-stage liver disease (MELD) scores (7.51 +/- 4.54 to 7.32 +/- 3.40) (p<0.05). Of the patients, 2 were diagnosed with HCC during the treatment and 14 were diagnosed with HCC 37.0 +/- 16.0 weeks post-treatment. Higher initial MELD score (odds ratio [OR]: 1.92, 95% confidence interval [CI]: 1.22-2.38; p=0.023]), higher hepatitis C virus (HCV) RNA levels (OR: 1.44, 95% CI: 1.31-2.28; p=0.038), and higher serum ALT levels (OR: 1.38, 95% CI: 1.21-1.83; p=0.042) were associated with poor SVR12. The most common adverse events were fatigue (12.6%), pruritis (7.3%), increased serum ALT (4.7%) and bilirubin (3.8%) levels, and anemia (3.1%).Conclusion: LDV/SOF or PrOD +/- RBV were effective and tolerable treatments for patients with CHC and with or without advanced liver disease before and after liver transplantation. Although HCV eradication improves the liver function, there is a risk of developing HCC.Turkish Association for the Study of The Liver (TASL

Outcomes from elective colorectal cancer surgery during the SARS-CoV-2 pandemic

This study aimed to describe the change in surgical practice and the impact of SARS-CoV-2 on mortality after surgical resection of colorectal cancer during the initial phases of the SARS-CoV-2 pandemic