Late Quaternary paleoenvironmental reconstruction and paleoclimatic implications of the Aegean Sea (eastern Mediterranean) based on paleoceanographic indexes and stable isotopes

The Late Quaternary palaeoenvironmental evolution and the main palaeoceanographic changes of the Aegean Sea was reconstructed using planktonic foraminifera obtained from the sediments of a northern (SK-1) and a southern (NS-14) core site. Multivariate statistical approach, including Q-mode cluster and Principal Component (PCA) Analyses, gives an insight into the relationships between sea surface environmental changes between the north and south Aegean, and furthermore serves as a baseline data set for palaeoclimatic and palaeoceanographic reconstructions of the eastern Mediterranean Sea. Stable isotope analyses coupled with additional paleoceanographic (sea surface temperature (SST), productivity (SSP), stratification (S-index), upwelling (U-index), seasonality (Sn-index)) proxies provide insights into the sedimentological, hydrographic and trophic evolution and ecosystem dynamics of the Aegean Sea, and furthermore serve as a baseline data set for palaeoclimatic and palaeoceanographic reconstructions of the eastern Mediterranean Sea. Concentrating on the last ~19 ka, faunal and isotopic data concur, suggesting a series of climatic zones, corresponding to well-known climatic phases of the last glacial cycle. Cold and arid conditions during the late glacial period were followed by a warmer and wetter climate trend during deglacial time. A marked seasonality, characterized by homogenous water column favored by efficient upwelling during the winter and by warm stratified water column during the summer, has also been recognized during this period (BøllingeAllerød e BeA) in both basins. An abrupt switch to cool, arid climatic event (Younger Dryas e YD) suggests a strengthening of winter convection around 12.9 ka, which seems to be more evident in the north Aegean core. However, the more pronounced environmental changes between the north and south Aegean Sea were identified during the Holocene, and they coincide with the deposition of sapropel S1 and Sapropel-Mid-Holocene (SMH). The comparison between SK-1 and NS-14 records indicated significant changes in both the productivity and stratification patterns, with the former the main factor in north Aegean and the latter in south Aegean for S1 deposition. Regarding the localized deposition of SMH in the semi-enclosed shallow south Aegean site, the fully oxygenated and less productive water column conditions prevailing during that time (5.4 e4.3 ka) in the north Aegean were the limiting factor for its deposition

Design of Variable Geometry Waste Heat Recovery Turbine for High Efficiency Internal Combustion Engine

This study was carried out for a 1.25L Zetec-SE DOHC engine model but its application is generic to gasoline engine (light-duty engine) applications. An ORC model with a radial turbine sub-model is implemented in a light-duty gasoline I.C engine model, to evaluate the impact of the ORC with VGT on the engine fuel consumption, net power output and finally the ORC system efficiency as compared to ORC with FGT. The results showed that VGT can improve ORC system efficiency and net power output by an unweighted point of 5.6% and 3.07kW respectively at partial to high load conditions while benefits are even higher at the lower loads therefore making it an attractive technology given its ability to recover low-grade heat and the possibility to be implemented in decentralized lower-capacity power plant

Radial turbine expander design for organic rankine cycle, waste heat recovery in high efficiency, off-highway vehicles

Although state-of-the-art, heavy duty diesel engines of today can reach peak thermal efficiencies of approximately 45%, still most of the fuel energy is transformed into wasted heat in the internal combustion process. Recovering this wasted energy could increase the overall thermal efficiency of the engine as well as reduce the exhaust gas emissions. Compared to other Waste Heat Recovery (WHR) technologies, Organic Rankine Cycle (ORC) systems are regarded favourably due to their relative simplicity and small back pressure impact on engine performance and fuel consumption. The key elements affecting the efficiency of the ORC system are the type of working fluid selected and the design of the expander. In this simulation study, a zero-dimensional, design code has been developed to explore the impact of two, common, refrigerant working fluids on the design of a radial turbine expander. In addition, an off-design turbine analysis has been applied in order to evaluate the performance of the expander in the ORC cycle at various engine operating points. Moreover, the evaluation of ORC-diesel engine on improving fuel consumption, brake power, brake torque and exhaust gas emissions is investigated. Compared to a conventional diesel powertrain system, WHR showed an up to 5.7 % increase in brake torque and brake power and a 5.4% reduction in the brake specific fuel consumption (bsfc). The results also showed that the working fluid selection and the expander speed are critical parameters on the performance of the proposed hybrid powertrain configuration

Diagnostic Value of Assessment Tools for Sciatica in Clinical Practice: A Systematic Review and Narrative Synthesis

BACKGROUND: Sciatica is one of the most common reasons for seeking healthcare for musculoskeletal pain and can be a challenge to healthcare providers to diagnose and treat. In view of the variability of sciatica symptoms, a great range of patient reported outcome measures (PROMs) and performance-based measures (PBOs) have been developed for its assessment and management, with however, often poor or controversial results in their reliability and discriminative ability.  Accurate diagnosis of sciatica is crucial to ensure appropriate intervention is given. However, to date there is no gold standard to diagnose sciatica. There has been no systematic review conducted to compare the diagnostic validity of assessment tools of sciatica. OBJECTIVE: To evaluate the diagnostic value of tools (PROMs and PBOs) used to assess patients presenting with sciatica. METHODS: This review informed and reported in line with the Preferred Reporting Items for Systematic Reviews and Meta-Analysis-Protocols. PubMed, Science Direct, Cochrane Library, CINAHL, MEDLINE, EMBASE, key journals and grey literature searched rigorously to find diagnostic accuracy studies investigating patient with sciatica. Two independent reviewers conducted the search, extracted the data and assessed risk of bias for included studies using the Quality Assessment of Diagnostic Accuracy Studies 2 tool. The overall quality of included studies evaluated using Grading of Recommendations, Assessment, Development and Evaluation guidelines.  RESULTS: From 8347 studies, 11 studies were included. Nine studies out of the 11 were at risk of bias. Very low level evidence supports the use of dermatomal patterns and low level evidence supports the use of 7 tools (neurological examination, Βragard test, S-LANSS, ID Pain, PDQ, S-DN4, SQST) for diagnosing sciatica. Moderate level evidence supports a cluster of eight signs (age, duration of disease, paroxysmal pain, pain worse in leg than back, typical dermatomal distribution, worse on coughing/sneezing/straining, finger to floor distance and paresis), twenty items of patient history, self-reported items (pain below knee,  which pain worst, numbness pins and needles), question «worsening of pain during sneezing coughing and straining» and Slump test for diagnosing sciatica. Also, moderate level evidence supports the use of the StEP tool for diagnosing lumbar radicular pain, demonstrating high sensitivity (92%) and specificity (97%) values. SLR showed moderate level evidence in one study and high level evidence in another study in diagnosing sciatica with sensitivity 63.46% and specificity 45.88%. CONCLUSIONS: Overall low-moderate level evidence supports the diagnostic utility of the tools examined in this review in diagnosing sciatica.  The weak evidence base is largely due to methodological flaws and indirectness regarding applicability of the included studies. The most promising diagnostic tools include a cluster of 8 patient history/clinical examination signs, the StEP tool and the SLR test. From these results it is easily understood that history taking has a major role as assessment tool of sciatica in clinical practice. Low risk of bias and high level of evidence diagnostic utility studies are needed, in order for stronger recommendations to be mad

Conservative management for an esophageal perforation in a patient presented with delayed diagnosis: a case report review of the literature

Esophageal perforation is a serious condition with a high mortality rate. Successful therapy depends on the size of the rupture; the time elapsed between rupture and diagnosis, and the underlying health of the patient. Common causes of esophageal perforation include medical instrumentation, foreign-body ingestion, and trauma. A case of esophageal perforation due to fish bone ingestion in a 67-year-old male is described here, with a review of the pertinent literature. The patient presented with chest pain, fever and right-sided pleural effusion. Initial evaluation was nondiagnostic. The water-soluble contrast swallow test showed no evidence of leakage. Computed tomography scan demonstrated a pneumomediastinum, and right-sided hydropneumothorax. The patient was successfully treated using conservative measures