Numerical study of the high-speed bypass effect on a plate-fin type heat exchanger

Heat exchangers having a bypass stream have wide ranging engineering applications such as heat sinks for electronics cooling. Due to their operating conditions, studies on the effect of the bypass region on the aero-thermal performance of heat exchangers have usually focused on the low-speed flow regime. Recently, however, the need for research on the high-speed bypass effect is increasing, especially in connection to aero-engine applications. The surface cooler, which is mounted on the fan casing of an aero-engine, uses a cold bypass stream to dissipate the heat from the oil system or the power generator devices of the engine. In this paper, a fundamental numerical study to evaluate the aero-thermal characteristics of a fin-type heat exchanger having a bypass duct under high-stream operating conditions has been conducted. A simplified bypass duct model has been used to formulate new performance correlations of the pressure drop and heat transfer coefficient by varying the bypass ratio and other important geometric parameters. The tested Mach number of the bypass stream was as high as 0.6. The obtained results are compared with previous low-speed correlations in both qualitative and quantitative terms. The newly summarized correlations could be useful for the preliminary design of heat exchangers for high-speed operating conditions in the early stage of the heat exchanger design. Comparison between the flow-network analysis results and the two-dimensional calculations showed the advantage of using the new correlations.Papers presented to the 12th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Costa de Sol, Spain on 11-13 July 2016

Korea HIV/AIDS Cohort Study: study design and baseline characteristics

The number of persons infected by HIV/AIDS has consistently increased in Korea since the first case of HIV/AIDS infection in 1985 and reached 15,208 by 2016. About 1,100 new patients with HIV/ AIDS infections have emerged every year since 2013. In Korea, the Korea HIV/AIDS Cohort Study was established for the evidenced-based prevention, treatment, and effective management of patients infected with human immunodeficiency virus (HIV) in December 2006. This study monitored 1,438 patients, who accounted for about 10% of all patients with HIV/AIDS in Korea, for 10 years with the following aims: (1) to develop an administrative system for the establishment of a HIV/AIDS cohort-based study; (2) to standardize methodologies and the case report forms; and (3) to standardize multi-cohort data and develop a data cleaning method. This study aims to monitor at least 1,000 patients (excluding those for whom investigation had been completed) per year (estimated number of patients who can be monitored by January 2018: 939). By December 2016, the sex distribution was 93.3% for men, and 6.7% for women (gender ratio, 13.9:1.0), and 98.9% of all participants were Korean. More than 50.0% of the participants were confirmed as HIV positive after 2006. This study reports competitive, long-term research that aimed to develop policies for the prevention of chronic infectious diseases for patients with HIV. The data collected over the last decade will be used to develop indices for HIV treatment and health promotion

Efficacy and Tolerability of Peginterferon Alpha Plus Ribavirin in the Routine Daily Treatment of Chronic Hepatitis C Patients in Korea: A Multi-Center, Retrospective Observational Study

Background/Aims: We aimed to evaluate the efficacy and safety of peginterferon plus ribavirin for chronic hepatitis C (CHC) patients under real life setting in Korea. Methods: We retrospectively analyzed the medical records of 758 CHC patients treated with peginterferon plus ribavirin between 2000 and 2008 from 14 university hospitals in the Gyeonggi-Incheon area in Korea. Results: Hepatitis C virus (HCV) genotype 1 was detected in 61.2% of patients, while genotype 2 was detected in 35.5%. Baseline HCV RNA level was >= 6x10(5) IU/mL in 51.6% of patients. The sustained virological response (SVR) rate was 59.6% regardless of genotype; 53.6% in genotype 1 and 71.4% in genotype 2/3. On multivariate analysis, male gender (p=0.011), early virological response (p<0.001), genotype 2/3 (p<0.001), HCV RNA <6x10(5) IU/mL (p=0.005) and adherence to the drug >80% of the planned dose (p<0.001) were associated with SVR. The rate of premature discontinuation was 35.7%. The main reason for withdrawal was intolerance to the drug due to common adverse events or cytopenia (48.2%). Conclusions: Our data suggest that the efficacy of peginterferon and ribavirin therapy in Koreans is better in Koreans than in Caucasians for the treatment of CHC, corroborating previous studies that have shown the superior therapeutic efficacy of this regimen in Asians.This study was supported by the Korean Association for the Study of the Liver in 2009

Erratum: Global, regional, and national comparative risk assessment of 84 behavioural, environmental and occupational, and metabolic risks or clusters of risks for 195 countries and territories, 1990–2017: a systematic analysis for the Global Burden of Disease Study 2017

Interpretation: By quantifying levels and trends in exposures to risk factors and the resulting disease burden, this assessment offers insight into where past policy and programme efforts might have been successful and highlights current priorities for public health action. Decreases in behavioural, environmental, and occupational risks have largely offset the effects of population growth and ageing, in relation to trends in absolute burden. Conversely, the combination of increasing metabolic risks and population ageing will probably continue to drive the increasing trends in non-communicable diseases at the global level, which presents both a public health challenge and opportunity. We see considerable spatiotemporal heterogeneity in levels of risk exposure and risk-attributable burden. Although levels of development underlie some of this heterogeneity, O/E ratios show risks for which countries are overperforming or underperforming relative to their level of development. As such, these ratios provide a benchmarking tool to help to focus local decision making. Our findings reinforce the importance of both risk exposure monitoring and epidemiological research to assess causal connections between risks and health outcomes, and they highlight the usefulness of the GBD study in synthesising data to draw comprehensive and robust conclusions that help to inform good policy and strategic health planning

Numerical studies of natural convection phenomena for a vertical cylinder with multiple lateral baffles in triangular and hexagonal enclosures

Numerical case studies for natural convection were conducted for triangular and hexagonal enclosures as a follow-up to a previous study of natural convection for a baffled cylinder in a square enclosure. For a Prandtl number of 0.71, a range of the length ratio corresponding to the spatial ratio was varied from 0.4 to 0.9, and Rayleigh numbers from 2.5 × 103 to 5.0 × 107 was considered. To model the buoyancy force, the Boussinesq approximation was adopted. The boundary condition of constant wall temperature was applied to the cylinder and enclosure surfaces. Overall trends of the heat transfer performance were separated into conduction- and convection-dominated regimes, similar to the previous study. Because of the wider space of the triangular enclosure, however, an advantage of the convection effect was observed in the triangular enclosure. Due to the short distance between the cylinder and enclosure, the hexagonal enclosure had a more conduction-dominated characteristic than that of the triangular enclosure. A strong correlation was identified between the location of the high-energy vortex and the Nusselt number distribution. Using the calculation results, an improved average Nusselt number correlation is proposed to include triangular, square and hexagonal enclosures

Experimental investigation of the effects of inclinations and wicks on the thermal behavior of heat pipes for improved thermal applications

Given the highly complex thermo-hydrodynamic features in heat pipes (HPs) but the inevitable need for efficient thermal solutions, this study investigated the effects of various wick types on the time-dependent thermal behavior of HPs. The results revealed that varying the cooling conditions and wick types in parallel is necessary for peak performance. Appropriate cooling lengths and temperatures improve the thermal limits of HPs with low-performing wicks. The composite wicks prompted faster steady performance, smooth startup, and low instabilities. Heat increment from 25 to 200 W decreased the thermal resistance from 1.75 to 0.05 °C/W. The HPs with homogeneous wicks have higher thermal resistance than those with composite wicks. Increased cooling lengths improve the performance of the former HPs. Inclining the HPs at angles relative to the horizontal position improves the HPs' thermal limits. The composite wicks minimized the effects of inclinations on the HPs’ performance. The HPs with composite multi-layered wicks presented transient profiles typical of first-order systems, whereas homogenous multi-layered wicks have complex responses upon step heat input. The transient profiles offer great insight into the instability inside the HPs. This study may guide future optimization analysis in selecting the best HPs and wicks for improved thermal management

Functional Reorganization Associated with Semantic Language Processing in Temporal Lobe Epilepsy Patients after Anterior Temporal Lobectomy : A Longitudinal Functional Magnetic Resonance Image Study

Objective : The focus of this study is brain plasticity associated with semantic aspects of language function in patients with medial temporal lobe epilepsy (mTLE). Methods : Using longitudinal functional magnetic resonance imaging (fMRI), patterns of brain activation were observed in twelve left and seven right unilateral mTLE patients during a word-generation task relative to a pseudo-word reading task before and after anterior temporal section surgery. Results : No differences were observed in precentral activations in patients relative to normal controls (n = 12), and surgery did not alter the phonological-associated activations. The two mTLE patient groups showed left inferior prefrontal activations associated with semantic processing (word-generation > pseudo-word reading), as did control subjects. The amount of semantic-associated activation in the left inferior prefrontal region was negatively correlated with epilepsy duration in both patient groups. Following temporal resection, semantic-specific activations in inferior prefrontal region became more bilateral in left mTLE patients, but more left-lateralized in right mTLE patients, The longer the duration of epilepsy in the patients, the larger the increase in the left inferior prefrontal semantic-associated activation after surgery in both patient groups. Semantic activation of the intact hippocampus, which had been negatively correlated with seizure frequency, normalized after the epileptic side was removed. Conclusion : These results indicate alternation of semantic language network related to recruitment of left inferior prefrontal cortex and functional recovery of the hippocampus contralateral to the epileptogenic side, suggesting an intra- and inter-hemispheric reorganization following surgery.Kim CH, 2009, J KOREAN NEUROSURG S, V45, P219, DOI 10.3340/jkns.2009.45.4.219Morgan RJ, 2008, P NATL ACAD SCI USA, V105, P6179, DOI 10.1073/pnas.0801372105Wada J, 2007, J NEUROSURG, V106, P1117Hickok G, 2007, NAT REV NEUROSCI, V8, P393, DOI 10.1038/nrn2113Bonilha L, 2007, EPILEPSIA, V48, P571, DOI 10.1111/j.1528-1167.2006.00958.xThivard L, 2007, EPILEPSIA, V48, P599, DOI 10.1111/j.1528-1167.2006.00968.xWeber B, 2006, BRAIN, V129, P346, DOI 10.1093/brain/awh694Thivard L, 2005, NEUROIMAGE, V28, P682, DOI 10.1016/j.neuroimage.2005.06.045Noppeney U, 2005, BRAIN, V128, P1377, DOI 10.1093/brain/awh414Pataraia E, 2005, NEUROLOGY, V64, P481Squire LR, 2004, ANNU REV NEUROSCI, V27, P279, DOI 10.1146/annurev.neuro.27.070203.144130Scott SK, 2003, TRENDS NEUROSCI, V26, P100Adcock JE, 2003, NEUROIMAGE, V18, P423Blasi V, 2002, NEURON, V36, P159Hertz-Pannier L, 2002, BRAIN, V125, P361Chen K, 1999, NAT MED, V5, P888Thompson-Schill SL, 1999, NEURON, V23, P513Muller RA, 1998, J CHILD NEUROL, V13, P16Cox RW, 1996, COMPUT BIOMED RES, V29, P162WYLER AR, 1995, NEUROSURGERY, V37, P982DEMB JB, 1995, J NEUROSCI, V15, P5870WYLER AR, 1995, NEUROSURGERY, V37, P990

Thalamic changes in temporal lobe epilepsy with and without hippocampal sclerosis: A diffusion tensor imaging study

Objective: The seizure network may be different between temporal lobe epilepsy with hippocampal sclerosis (TLE + HS) and without HS (TLE - HS). Chronic seizure activity may alter the diffusion properties of a seizure network. The thalamus is known to have an anatomical connection to the medial temporal area and to play a role in seizure modulation. This study aimed to evaluate differences in thalamic changes between TLE + HS and TLE - HS with diffusion tensor imaging (DTI). Methods: Nine patients with TLE + HS and nine patients with TLE - HS were included in the study. All patients underwent surgery with good seizure outcomes. Hippocampal sclerosis was verified pathologically. Sixteen right-handed, normal subjects were enrolled as controls. DTI was acquired using 3.0 T MRI. The mean diffusivity (MD) and fractional anisotropy (FA) were calculated in the center of the bilateral thalamus with the DTIstudio program. Results: The MD of bilateral thalami increased in both TLE groups compared to controls (p0.05). Conclusion: Bilateral thalamic diffusion properties are altered in temporal lobe epilepsy. The presence of hippocampal sclerosis enhances the change ipsilaterally.Bertram EH, 2009, EPILEPSY BEHAV, V14, P32, DOI 10.1016/j.yebeh.2008.09.017Nilsson D, 2008, EPILEPSY RES, V81, P128, DOI 10.1016/j.eplepsyres.2008.05.002Labate A, 2008, NEUROLOGY, V71, P1094Riederer F, 2008, NEUROLOGY, V71, P419Gong G, 2008, EPILEPSY RES, V80, P184, DOI 10.1016/j.eplepsyres.2008.04.002Keller SS, 2008, EPILEPSIA, V49, P741, DOI 10.1111/j.1528-1167.2007.01485.xFocke NK, 2008, NEUROIMAGE, V40, P728, DOI 10.1016/j.neuroimage.2007.12.031Oouchi H, 2007, AM J NEURORADIOL, V28, P1102, DOI 10.3174/ajnr.A0488Kim CH, 2007, J NEUROSURG, V106, P111Gross DW, 2006, EPILEPSIA, V47, P1360, DOI 10.1111/j.1528-1167.2006.00603.xMueller SG, 2006, EPILEPSIA, V47, P900Kimiwada T, 2006, EPILEPSIA, V47, P167Thivard L, 2005, NEUROIMAGE, V28, P682, DOI 10.1016/j.neuroimage.2005.06.045Concha L, 2005, ANN NEUROL, V57, P188, DOI 10.1002/ana.20334PALMINI A, 2004, NEUROLOGY, V62, P2Kim YK, 2003, J NUCL MED, V44, P1006Natsume J, 2003, NEUROLOGY, V60, P1296Choi JY, 2003, EUR J NUCL MED MOL I, V30, P581, DOI 10.1007/s00259-002-1079-8Arfanakis K, 2002, MAGN RESON IMAGING, V20, P511Yoo SY, 2002, AM J NEURORADIOL, V23, P809Bertram EH, 2001, EPILEPSIA, V42, P967Kim YH, 2001, KOREAN J RADIOL, V2, P63Rugg-Gunn FJ, 2001, BRAIN, V124, P627Eriksson SH, 2001, BRAIN, V124, P617Diehl B, 2001, EPILEPSIA, V42, P21Newberg AB, 2000, J NUCL MED, V41, P1964Men S, 2000, AM J NEURORADIOL, V21, P1837Diehl B, 1999, EPILEPSIA, V40, P1667Bertram EH, 1999, NEUROSCIENCE, V92, P15Baulac M, 1998, ANN NEUROL, V44, P223Ho SS, 1998, NEUROLOGY, V50, P748ENGEL J, 1993, SURG TREATMENT EPILE, P553OLDFIELD RC, 1971, NEUROPSYCHOLOGIA, V9, P97

Diethylnitrosamine (DEN) induces irreversible hepatocellular carcinogenesis through overexpression of G(1)/S-phase regulatory proteins in rat

Hepatocellular carcinoma (HCC) is the fifth most frequent cause of cancer deaths in males and was the third most frequent cause of cancer deaths in 2007 throughout the world. The incidence rate is 2-3 times higher in developing countries than in developed countries. Animal models have enabled study of the mechanism of HCC and the development of possible strategies for treatment. Diethylnitrosamine (DEN) is a representative chemical carcinogen with the potential to cause tumors in various organs, including the liver, skin, gastrointestinal tract, and respiratory system Specifically in HCC, DEN is a complete carcinogen. Many lines of evidence have demonstrated a relationship between carcinogenesis and cell cycle regulation. In this study we found that cell cycle regulatory proteins were critically involved in cancer initiation and promotion by DEN. Cyclin D1. cyclin E, cdk4. and p21(CIP1/WAF1) I are factors whose expression levels may be useful as criteria for the classification of hepatic disease. In particular, cdk4 had a pivotal role in the transition to the neoplastic stage. In conclusion. we suggest that changes in the level of cdk4 may be useful as a biomarker for detection of HCC. (C) 2009 Elsevier Ireland Ltd. All rights reservedChang JJ, 2008, MOL CELL TOXICOL, V4, P278Sell S, 2008, TUMOR BIOL, V29, P161, DOI 10.1159/000143402*AM CANC SOC, 2007, GLOB CAN FACTS FIG 2Kim MR, 2005, EXP MOL MED, V37, P335LI X, 2005, HEPATOB PANCREAT DIS, V4, P427Masaki T, 2003, HEPATOLOGY, V37, P534, DOI 10.1053/jhep.2003.50112Pascale RM, 2002, HEPATOLOGY, V35, P1341, DOI 10.1053/jhep.2002.33682Masaki T, 2000, HEPATOLOGY, V32, P711, DOI 10.1053/jhep.2000.17705Perez-Roger I, 1999, EMBO J, V18, P5310Johnson PJ, 1999, J GASTROEN HEPATOL, V14, pS32Verna L, 1996, PHARMACOL THERAPEUT, V71, P57SHERR CJ, 1994, CELL, V79, P551HUNTER T, 1994, CELL, V79, P573HUNTER T, 1991, CELL, V66, P1071PITOT HC, 1991, ENVIRON HEALTH PERSP, V93, P181DRAGAN YP, 1991, PREV MED, V20, P15XU YH, 1990, CANCER RES, V50, P472BEER DG, 1987, ARCH TOXICOL S, V10, P68RAO MS, 1986, CANCER RES, V46, P5287FARBER E, 1984, CANCER RES, V44, P4217WARD JM, 1981, VIRCHOWS ARCH A, V390, P339COHEN AH, 1976, J CLIN PATHOL, V65, P631ANDERSEN P, 1976, CLIN EXP IMMUNOL, V26, P57