117 research outputs found

    Optimum Electrical Resistivity Tomography (OERT) approach using combination of different arrays in archaeological investigations

    Get PDF
    In this study, the optimum electrical resistivity tomography (OERT) concept was analyzed by combining different electrode arrays in terms of sensitivity in archaeological cases. More than a hundred electrode arrays were classified by Szalai & Szarka (2008), investigating the superposition, focusing and linearity problem. Also, Dahlin & Zhou (2004) compared images resulting from various configurations. However, the difficulties posed by apparent resistivity due to different characteristics of ..

    Investigation of Polishing Abilities of Undergraduates and Postgraduates by Using Various Systems on Composite Materials

    Get PDF
    Background: The purpose of dental education is to enable students to gain the knowledge and skills to provide the best service to their patients upon graduation. In order to achieve this, students need to work with a sufficient number of cases and use current materials throughout their education. Aim: The aim of this in vitro study, conducted in 2017, was to examine the surface roughness of two types of composites prepared with different polishing systems, constructed by either undergraduate or doctoral students. Methods: Bulk-fill (Filtek Bulk Fill Posterior) and nano-hybrid (Ceram.x One Universal) composites were polished using single-step (OneGloss Set) and multi-step (Sof-Lex System) systems. The finishing and polishing procedures were performed by ten dental undergraduate students and ten doctoral students. Average surface roughness values (Ra, µm) were measured using a profilometer. Data were analyzed using the Wilcoxon signed-rank test (α = 0.05). Results: No statistically significant differences in Ra values were noted between operators with different levels of experience. Surface roughness was higher in the samples prepared using the single-step system than in those prepared using the multi-step system for both sample types tested in this study. Conclusion: Practitioner ability does not affect the performance of polishing systems. Regardless of the composite type, the single-step polishing system produces rougher surfaces than the multi-step system

    Integrated usage of geophysical prospection techniques in Höyük (tepe, tell)-type archaeological settlements

    Get PDF
    The integrated use of geophysical methods has developed rapidly in the last fifteen years in archaeological prospection (Brizzolari et al., 1992; Gaffney et al., 2004; Drahor, 2006; Casana et al., 2008). The combined application of different geophysical techniques supplies useful information about buried archaeological contexts, particularly höyük(tell, tepe)-type archaeological settlements. The aim of such studies is to help archaeologists conduct fast, effective and economical excavations b..

    Elaia, Pergamon's maritime satellite:The rise and fall of an ancient harbour city shaped by shoreline migration

    Get PDF
    Throughout human history, communication and trade have been key to society. Because maritime trade facilitated the rapid transportation of passengers and freight at relatively low cost, harbours became hubs for traffic, trade and exchange. This general statement holds true for the Pergamenian kingdom, which ruled wide parts of today's western Turkey during Hellenistic times. Its harbour, located at the city of Elaia on the eastern Aegean shore, was used extensively for commercial and military purposes. This study reconstructs the coastal evolution in and around the ancient harbour of Elaia and compares the observed environmental modifications with archaeological and historical findings. We use micropalaeontological, sedimentological and geochemical proxies to reconstruct the palaeoenvironmental dynamics and evolution of the ancient harbour. The geoarchaeological results confirm the archaeological and historical evidence for Elaia's primacy during Hellenistic and early Roman times, and the city's gradual decline during the late Roman period. Furthermore, our study demonstrates that Elaia holds a unique position as a harbour city during ancient times in the eastern Aegean region, because it was not greatly influenced by the high sediment supply associated with river deltas. Consequently, no dredging of the harbour basins is documented, creating exceptional geo-bioarchives for palaeoenvironmental reconstructions

    Intraperitoneal drain placement and outcomes after elective colorectal surgery: international matched, prospective, cohort study

    Get PDF
    Despite current guidelines, intraperitoneal drain placement after elective colorectal surgery remains widespread. Drains were not associated with earlier detection of intraperitoneal collections, but were associated with prolonged hospital stay and increased risk of surgical-site infections.Background Many surgeons routinely place intraperitoneal drains after elective colorectal surgery. However, enhanced recovery after surgery guidelines recommend against their routine use owing to a lack of clear clinical benefit. This study aimed to describe international variation in intraperitoneal drain placement and the safety of this practice. Methods COMPASS (COMPlicAted intra-abdominal collectionS after colorectal Surgery) was a prospective, international, cohort study which enrolled consecutive adults undergoing elective colorectal surgery (February to March 2020). The primary outcome was the rate of intraperitoneal drain placement. Secondary outcomes included: rate and time to diagnosis of postoperative intraperitoneal collections; rate of surgical site infections (SSIs); time to discharge; and 30-day major postoperative complications (Clavien-Dindo grade at least III). After propensity score matching, multivariable logistic regression and Cox proportional hazards regression were used to estimate the independent association of the secondary outcomes with drain placement. Results Overall, 1805 patients from 22 countries were included (798 women, 44.2 per cent; median age 67.0 years). The drain insertion rate was 51.9 per cent (937 patients). After matching, drains were not associated with reduced rates (odds ratio (OR) 1.33, 95 per cent c.i. 0.79 to 2.23; P = 0.287) or earlier detection (hazard ratio (HR) 0.87, 0.33 to 2.31; P = 0.780) of collections. Although not associated with worse major postoperative complications (OR 1.09, 0.68 to 1.75; P = 0.709), drains were associated with delayed hospital discharge (HR 0.58, 0.52 to 0.66; P < 0.001) and an increased risk of SSIs (OR 2.47, 1.50 to 4.05; P < 0.001). Conclusion Intraperitoneal drain placement after elective colorectal surgery is not associated with earlier detection of postoperative collections, but prolongs hospital stay and increases SSI risk

    Temperature Effects Explain Continental Scale Distribution of Cyanobacterial Toxins

    Get PDF
    Insight into how environmental change determines the production and distribution of cyanobacterial toxins is necessary for risk assessment. Management guidelines currently focus on hepatotoxins (microcystins). Increasing attention is given to other classes, such as neurotoxins (e.g., anatoxin-a) and cytotoxins (e.g., cylindrospermopsin) due to their potency. Most studies examine the relationship between individual toxin variants and environmental factors, such as nutrients, temperature and light. In summer 2015, we collected samples across Europe to investigate the effect of nutrient and temperature gradients on the variability of toxin production at a continental scale. Direct and indirect effects of temperature were the main drivers of the spatial distribution in the toxins produced by the cyanobacterial community, the toxin concentrations and toxin quota. Generalized linear models showed that a Toxin Diversity Index (TDI) increased with latitude, while it decreased with water stability. Increases in TDI were explained through a significant increase in toxin variants such as MC-YR, anatoxin and cylindrospermopsin, accompanied by a decreasing presence of MC-LR. While global warming continues, the direct and indirect effects of increased lake temperatures will drive changes in the distribution of cyanobacterial toxins in Europe, potentially promoting selection of a few highly toxic species or strains.Peer reviewe

    Reducing the environmental impact of surgery on a global scale: systematic review and co-prioritization with healthcare workers in 132 countries

    Get PDF
    Background Healthcare cannot achieve net-zero carbon without addressing operating theatres. The aim of this study was to prioritize feasible interventions to reduce the environmental impact of operating theatres. Methods This study adopted a four-phase Delphi consensus co-prioritization methodology. In phase 1, a systematic review of published interventions and global consultation of perioperative healthcare professionals were used to longlist interventions. In phase 2, iterative thematic analysis consolidated comparable interventions into a shortlist. In phase 3, the shortlist was co-prioritized based on patient and clinician views on acceptability, feasibility, and safety. In phase 4, ranked lists of interventions were presented by their relevance to high-income countries and low–middle-income countries. Results In phase 1, 43 interventions were identified, which had low uptake in practice according to 3042 professionals globally. In phase 2, a shortlist of 15 intervention domains was generated. In phase 3, interventions were deemed acceptable for more than 90 per cent of patients except for reducing general anaesthesia (84 per cent) and re-sterilization of ‘single-use’ consumables (86 per cent). In phase 4, the top three shortlisted interventions for high-income countries were: introducing recycling; reducing use of anaesthetic gases; and appropriate clinical waste processing. In phase 4, the top three shortlisted interventions for low–middle-income countries were: introducing reusable surgical devices; reducing use of consumables; and reducing the use of general anaesthesia. Conclusion This is a step toward environmentally sustainable operating environments with actionable interventions applicable to both high– and low–middle–income countries

    Reducing the environmental impact of surgery on a global scale: systematic review and co-prioritization with healthcare workers in 132 countries

    Get PDF
    Abstract Background Healthcare cannot achieve net-zero carbon without addressing operating theatres. The aim of this study was to prioritize feasible interventions to reduce the environmental impact of operating theatres. Methods This study adopted a four-phase Delphi consensus co-prioritization methodology. In phase 1, a systematic review of published interventions and global consultation of perioperative healthcare professionals were used to longlist interventions. In phase 2, iterative thematic analysis consolidated comparable interventions into a shortlist. In phase 3, the shortlist was co-prioritized based on patient and clinician views on acceptability, feasibility, and safety. In phase 4, ranked lists of interventions were presented by their relevance to high-income countries and low–middle-income countries. Results In phase 1, 43 interventions were identified, which had low uptake in practice according to 3042 professionals globally. In phase 2, a shortlist of 15 intervention domains was generated. In phase 3, interventions were deemed acceptable for more than 90 per cent of patients except for reducing general anaesthesia (84 per cent) and re-sterilization of ‘single-use’ consumables (86 per cent). In phase 4, the top three shortlisted interventions for high-income countries were: introducing recycling; reducing use of anaesthetic gases; and appropriate clinical waste processing. In phase 4, the top three shortlisted interventions for low–middle-income countries were: introducing reusable surgical devices; reducing use of consumables; and reducing the use of general anaesthesia. Conclusion This is a step toward environmentally sustainable operating environments with actionable interventions applicable to both high– and low–middle–income countries

    The effect of pre-ozone oxidation on acute toxicity and inert soluble COD fractions of a textile finishing industry wastewater.

    No full text
    The present work evaluates pre-ozonation for removal of acute toxicity, color and COD as well as reduction of inert soluble COD fractions in two wastewater samples (S1 and S2) taken from a textile finishing industry, located in Istanbul (Turkey). The wastewater samples were oxidized at original pH of 8.6-8.8 under 18.5-24 mg/L of applied ozone doses. Acute toxicity was monitored using Daphnia magna. The results showed that pre-ozonation improved the biodegradability and reduced the acute toxicity. Acute toxicity in raw wastewaters was reduced by 80-90% using 129-200 mg/L transferred ozone (TrO(3)) concentrations. At this point, 86-96% of color, 33-39% of soluble COD and 57-64% of total COD were removed from wastewaters. Both color and COD parameters were found related to the acute toxicity of the wastewater. Pre-ozonation decreased the inert soluble COD fraction (S(I)) of raw wastewater while soluble product formation (S(P)) increased slightly (5-10 mg/L). However, residual COD (the sum of S(I) and S(P)) remained below discharge limit
    corecore