bluuebunny/crossref_metadata_2025 huggingface dataset:
P‐Wave Duration and Dispersion in Patients with Metabolic Syndrome
Authors: YASAR AYSE SAATCI , BILEN EMINE , BILGE MEHMET , IPEK GOKTURK , IPEK EMRAH , KIRBAS OZGUR
Published: August 2009

Background: Metabolic syndrome (MS) has been reported to be associated with an increased risk of atrial fibrillation (AF). The aim of this study was to investigate P‐wave dispersion (PWD) in patients with MS.

Methods: The study population included 66 patients with MS (21 men, 45 women; mean age, 49.7 ± 9.1 years) and 63 control subjects without MS (26 men, 37 women; mean age, 47.0 ± 10.6 years). The diagnosis of MS was based on the National Cholesterol Education Program Adult Treatment Panel III criteria. A 12‐lead electrocardiogram was recorded for each subject. The difference between maximum and minimum P‐wave duration was calculated and defined as PWD. An echocardiographic examination was also performed for each subject.

Results: Maximum P‐wave duration and PWD were found to be significantly higher in patients with MS compared with the control subjects (Maximum P‐wave duration: 113.5 ± 9.7 ms vs 101.0 ± 8.1 ms, PWD: 37.8 ± 7.6 vs 23.3 ± 5.9, respectively, P < 0.001 for both). However, there was no statistically significant difference between two groups regarding minimum P‐wave duration (75.6 ± 6.9 ms vs 77.6 ± 7.8 ms, respectively, P = 0.18). In addition, PWD was positively correlated with age, body mass index, waist circumference, systolic and diastolic blood pressure, triglyceride level, deceleration time, isovolumetric relaxation time and negatively correlated with high‐density lipoprotein cholesterol level and early‐to‐late diastolic velocity ratio.

Conclusion: We have shown that patients with MS have higher PWD, indicating increased risk for AF, compared to the control subjects without MS.
Initiation of Ventricular Tachycardia by Interruption of Pacemaker‐Mediated Tachycardia in a Patient with a Dual‐Chamber Implantable Cardioverter Defibrillator
Authors: VAN GELDER BERRY M. , MEIJER ALBERT , DEKKER LUKAS R. , BRACKE FRANK A.
Published: August 2009

A 74‐year‐old man with a dual‐chamber implantable cardioverter defibrillator implanted 3 years before experienced multiple ventricular tachycardias (VTs). All episodes were initiated by pacemaker‐mediated tachycardia (PMT) that was either stopped by atrial undersensing or the tachycardia termination algorithm of the device. After the termination of PMT, two rapid ventricular paced beats, the first initiated by artificial triggering and the second due to retrograde conduction of the first one, initiated VT that was successfully terminated by antitachycardia pacing or a direct current shock of the device
. All episodes revealed this pattern of initiation with a short‐long‐short ventricular sequence inducing VT.
New immigrant settlement in a mid‐sized city: a case study of housing barriers and coping strategies in Kelowna, British Columbia
Authors: TEIXEIRA CARLOS
Published: August 2009

The successful integration of immigrants into a new society is based on their attainment of several basic needs, including access to adequate, suitable and affordable housing. While this has long been a concern in Canadian cities, such as Vancouver, Toronto, and Montréal, it is also increasingly an issue in growing mid‐sized cities such as Kelowna, in the interior of British Columbia. While Kelowna's real estate market is one of the most expensive in the country, there is little published data or literature on the housing experiences of immigrants in the city. This study examines the housing experiences and stresses of a small group of immigrants in Kelowna's rental housing market. This study uses data from five focus groups with 34 new immigrants and 20 interviews with key informants, conducted in Kelowna in summer 2008. The evidence indicates that for this group of immigrant newcomers, the housing search process in Kelowna's rental housing market met with significant barriers in locating affordable rental housing. Of these barriers, the most commonly cited were: (a) high housing costs; (b) lack of reliable housing information, including lack of access to organizations that provide housing help (government or not); and (c) prejudice by landlords based on the immigrants' ethnic and racial background.

This study points to the need for more comparative studies on the housing experiences of immigrants in mid‐sized cities in Canada to better understand which groups of immigrants are more successful than others in finding affordable housing in these mid‐sized cities, and why.
The urban in fragile, uncertain, neoliberal times: towards new geographies of social justice?
Authors: WALKS R. ALAN
Published: August 2009

Canadian cities are at a crossroads. The neoliberalization of governance at multiple scales, inadequate re‐investment in urban infrastructure, increasing reliance on continental and international trade, and the restructuring of the space economy have combined to weaken Canada's cities just as the global economic system is undergoing transformation. Canadian urban geographic scholarship has much to offer under current conditions, and is already making significant contributions in key areas. In particular, research on what might be called the contours and impacts of urban restructuring and the neoliberal city, immigration and cities of difference, and urban environmental justice show much promise and are likely to define the core of Canadian urban geography into the future.
An improved objective evaluation measure for border detection in dermoscopy images
Authors: Celebi M. Emre , Schaefer Gerald , Iyatomi Hitoshi , Stoecker William V. , Malters Joseph M. , Grichnik James M.
Published: August 2009

Background: Dermoscopy is one of the major imaging modalities used in the diagnosis of melanoma and other pigmented skin lesions. Owing to the difficulty and subjectivity of human interpretation, dermoscopy image analysis has become an important research area. One of the most important steps in dermoscopy image analysis is the automated detection of lesion borders. Although numerous methods have been developed for the detection of lesion borders, very few studies were comprehensive in the evaluation of their results.

Methods: In this paper, we evaluate five recent border detection methods on a set of 90 dermoscopy images using three sets of dermatologist‐drawn borders as the ground truth. In contrast to previous work, we utilize an objective measure, the normalized probabilistic rand index, which takes into account the variations in the ground‐truth images.

Conclusion: The results demonstrate that the differences between four of the evaluated border detection methods are in fact smaller than those predicted by the commonly used exclusive‐OR measure.
Acceptability and feasibility of infant‐feeding options: experiences of HIV‐infected mothers in the World Health Organization Kesho Bora mother‐to‐child transmission prevention (PMTCT) trial in Burkina Faso
Authors: Cames Cécile , Saher Aisha , Ayassou Kossiwavi A. , Cournil Amandine , Meda Nicolas , Simondon Kirsten Bork
Published: August 2009

In Burkina Faso, prolonged breastfeeding with introduction of ritual fluids from birth is a deep‐seated norm. We explored HIV‐infected mothers' views and experiences of the acceptability and feasibility of the World Health Organization's recommended infant‐feeding options within a mother‐to‐child‐transmission prevention trial. A qualitative study was conducted on 17 formula‐feeding and 19 breastfeeding mothers, from a larger cohort of 51 eligible HIV‐infected women, consenting to participate in separate focus group discussions in early post‐partum. Mothers opted for breastfeeding essentially out of fear of family rejection. Most of them were afraid of denigration for disrespecting tradition if they formula‐fed or being suspected of HIV infection. Achieving exclusive breastfeeding remained a difficult challenge as they engaged in a continuous struggle with close elders to avoid fluid feeding. Additional stress and fatigue were fed by their perception of a high transmission risk through breast milk. Exclusive formula‐feeding seemed easier to implement, especially as formula was provided free of charge. Formula‐feeding mothers more frequently had a supportive partner, a strong personality and lived in better socio‐economic conditions than breastfeeding mothers (76% had education and electricity supply vs. 42%, respectively). Exclusive breastfeeding for the first 6 months remains the most appropriate option for many HIV‐infected mothers in sub‐Saharan Africa. Its acceptability and feasibility urgently need to be improved by promoting it as the best feeding option for all infants. Other crucial interventions are the promotion of voluntary counselling and testing for couples, and greater partner involvement in infant‐feeding counselling.
Breastfeeding support – the importance of self‐efficacy for low‐income women
Authors: Entwistle Francesca , Kendall Sally , Mead Marianne
Published: August 2009

Breastfeeding is a key determinant in promoting public health and reducing health inequality. Low‐income women have a significantly lower level of breastfeeding. Midwives in the UK have been encouraged to implement the World Health Organization/United Nations Children's Fund's Ten Steps to Successful Breastfeeding, but to date, there has been no evaluation of the impact of the training initiative on the breastfeeding behaviours of low‐income women.

As part of a wider study, this qualitative component was designed to answer the question – what are the views and experiences of low‐income women (defined by Jarman scores) in relation to their breastfeeding support received in the post‐natal period?

A sample of seven women was interviewed. The in‐depth interviews were analysed using a qualitative, thematic approach based on the self‐efficacy theory. The four themes that emerged from the data were the following: breastfeeding related to the woman's self‐confidence, the social environment in which the woman lived, knowledge of breastfeeding and the influence of maternity services on breastfeeding outcomes. These themes were interpreted in relation to the self‐efficacy theory.

The findings suggest that the components that inform self‐efficacy are consistent with the themes from the data, suggesting that midwives and other health professionals should take the psychosocial aspects of breastfeeding support into account. As this important feature of breastfeeding support is not explicitly part of the current Ten Steps to Successful Breastfeeding, we suggest that further research and debate could inform expansion of these minimum standards to include the psychosocial aspects.
Terminology of Developmental Abnormalities in Common Laboratory Mammals (Version 2)
Authors: Makris Susan L. , Solomon Howard M. , Clark Ruth , Shiota Kohei , Barbellion Stephane , Buschmann Jochen , Ema Makoto , Fujiwara Michio , Grote Konstanze , Hazelden Keith P. , Hew Kok Wah , Horimoto Masao , Ooshima Yojiro , Parkinson Meg , Wise L. David
Published: August 2009

This update (Version 2) of the Terminology of Developmental Abnormalities in Common Laboratory Mammals (Version 1) incorporates improvements and enhancements to both content and organization of the terminology to enable greater flexibility in its application, while maintaining a consistent approach to the description of findings. The revisions are the result of an international collaboration among interested organizations, advised by individual experts and the outcomes of several workshops. The terminology remains organized into tables under the broad categories of external, visceral, and skeletal observations, following the manner in which data are typically collected and recorded in developmental toxicity studies. This arrangement of the tables, as well as other information provided in appendices, is intended to facilitate the process of specimen evaluation at the laboratory bench level. Only the commonly used laboratory mammals (i.e. rats, mice, rabbits) are addressed in the current terminology tables. The inclusion of other species that are used in developmental toxicity testing, such as primates, is considered outside the scope of the present update. Similarly, categorization of findings as, for example, ‘malformation’ or ‘variation’ remains unaddressed, in accordance with the overall principle that the focus of this document is descriptive terminology and not diagnosis or interpretation. The skeletal terms have been augmented to accommodate cartilage findings.
The use of Urgotul™ in the treatment of partial thickness burns and split‐thickness skin graft donor sites: a prospective control study
Authors: Tan Pearlie WW , Ho Wong Chin , Song Colin
Published: August 2009

The use of paraffin‐impregnated gauze for burns and skin graft donor sites is commonly associated with wound adherence with consequent pain and trauma upon removal. This prospective clinical study was performed to evaluate a new class of lipido‐colloid dressings (Urgotul™) in promoting healing and in reducing tissue adherence. In a 6‐month period, 25 consecutive patients were recruited. Two separate burn or donor sites on each patient were dressed with tulle‐gras (TG) or Urgotul™ and covered with standard secondary dressings. Objective assessment of wounds by two reviewers, and patients' subjective assessments were recorded. Twenty‐three (92%) patients were followed up for a mean of 3 months. Mean time to complete epithelialisation was 9·6 and 11·9 days for the Urgotul™ and TG sites respectively (P < 0·05). Bleeding was seen in 52% of Urgotul™ sites compared with 100% of the TG sites at first dressing change (P < 0·05). Patients reported ‘moderate pain’ during dressing change in 22% and 57% in the Urgotul™ and TG groups respectively (P < 0·05), with 35% of TG sites being ‘very painful’ requiring extra analgesia. We found that compared with TG, Urgotul™ was associated with faster epithelialisation, less pain and trauma (bleeding) during dressing changes.
Vacuum‐assisted closure of laparostomy wounds: a critical review of the literature
Authors: Stevens Philip
Published: August 2009

Vacuum‐assisted closure (VAC) reduces the burden for carers of laparostomy wounds but evidence from randomised trials is lacking. This review analyses the evidence for the VAC® abdominal wound management system (KCI, San Antonio, TX) in the open abdomen. Three prospective studies provide level III evidence that VAC® allows delayed primary fascial closure in the majority of these wounds up to 21 days after occurrence, but not where duration of VAC® was less than 9 days or if vacuum pack techniques were used in place of VAC®. Fistulae occurred in a minority of wounds complicated by multi‐organ failure or sepsis and could not be attributed to VAC® itself. Two retrospective analyses suggested VAC® may reduce re‐operation rate and length of stay in complex wounds. Whilst randomised controlled trials remain the gold standard of evidence for effectiveness of health care interventions, contemporaneous level III evidence supports the hypothesis that VAC® increases the rate of primary fascial closure. Whilst enterocutaneous fistula formation is reported in the most complex of these wounds, there is no more evidence that these are consequential to as opposed to coincident with VAC® use.
Antioxidative Responses of Two Marine Microalgae During Acclimation to Static and Fluctuating Natural UV Radiation
Authors: Janknegt Paul J. , De Graaff C. Marco , Van De Poll Willem H. , Visser Ronald J. W. , Helbling E. Walter , Buma Anita G. J.
Published: August 2009

Photoacclimation properties were investigated in two marine microalgae exposed to four ambient irradiance conditions: static photosynthetically active radiation (PAR: 400–700 nm), static PAR + UVR (280–700 nm), dynamic PAR and dynamic PAR + UVR. High light acclimated cultures of Thalassiosira weissflogii and Dunaliella tertiolecta were exposed outdoors for a maximum of 7 days. Dynamic irradiance was established by computer controlled vertical movement of 2 L bottles in a water filled basin. Immediate (<24 h), short‐term (1–3 days) and long‐term (4–7 days) photoacclimation was followed for antioxidants (superoxide dismutase, ascorbate peroxidase and glutathione cycling), growth and pigment pools. Changes in UVR sensitivity during photoacclimation were monitored by measuring UVR‐induced inhibition of carbon assimilation under standardized UV conditions using an indoor solar simulator. Both species showed immediate antioxidant responses due to their transfer to the outdoor conditions. Furthermore, upon outdoor exposure, carbon assimilation and growth rates were reduced in both species compared with initial conditions; however, these effects were most pronounced in D. tertiolecta. Outdoor UV exposure did not alter antioxidant levels when compared with PAR‐only controls in both species. In contrast, growth was significantly affected in the static UVR cultures, concurrent with significantly enhanced UVR resistance. We conclude that antioxidants play a minor role in the reinforcement of natural UVR resistance in T. weissflogii and D. tertiolecta.
Erythemal Ultraviolet Exposure in Two Groups of Outdoor Workers in Valencia, Spain
Authors: Serrano María Antonia , Cañada Javier , Moreno Juan Carlos ,   of the Solar Radiation Group
Published: August 2009

UVexposure is considered to be one of the most important risk factors in skin cancers, mainly in outdoor occupational activities. Outdoor workers receive regular and significant solar UV erythemal radiation (UVER). To quantify the UVER exposure of certain groups of workers, dosimeters are used to measure the biologically effective UV radiation received in the course of their daily work. Two groups of outdoor workers, composed of gardeners and lifeguards, were measured for UVER exposure using sensitive spore‐film filter‐type personal dosimeters (Viospor). The study took place in Valencia, Spain, in June and July 2008, and involved one group of four gardeners and another of five beach lifeguards for a period of 4 and 6 days, respectively. The gardeners’ mean UV exposure was 4.13 ± 0.60 SED day−1, where 1 SED is defined as effective 100 J m−2 when weighted with the CIE erythemal response function, whereas the lifeguards received 11.43 ± 2.15 SED day−1. The mean exposure ratio (ER) relative to ambient of gardeners was 0.09 ± 0.01 and for lifeguards was 0.27 ± 0.05. ER is defined as the ratio between the personal dose on a selected anatomical site and the corresponding ambient dose on a horizontal plane during the same exposure period. The lifeguards received the highest UVER exposure, although both groups had measured UVER exposure in excess of occupational guidelines, indicating that protective measures are necessary.
Exploitation of Immune Response‐eliciting Properties of Hypocrellin Photosensitizer SL052‐based Photodynamic Therapy for Eradication of Malignant Tumors
Authors: Korbelik Mladen , Merchant Soroush , Huang Naiyan
Published: August 2009

A diaminophenyl derivative of hypocrellin B (SL052) has been developed as a photosensitizer for use in photodynamic therapy (PDT) of solid tumors. Testing SL052‐PDT on mouse carcinoma and fibrosarcoma models revealed a typical response seen with clinically established photosensitizers featuring initial rapid tumor ablation with ensuing recurrence at rates dependent on photosensitizer/light doses. Elevated numbers of immune cells were found in lymph nodes draining SCCVII mouse squamous cell carcinomas treated by SL052‐PDT (in particular T cells), and the accumulation of degranulating cytotoxic T cells was detected at the tumor‐treated site. This indicates that a significant contribution to tumor cures is elicited by an antitumor adaptive immune response. Two different immunotherapy agents, γ‐interferon and antibody blocking inhibitory FcγRIIB receptor, were both found to be highly effective in potentiating the curative effect of SL052‐PDT with SCCVII tumors. Combining SL052‐PDT with FcγRIIB‐blocking antibody treatment caused a further increase in the number of cells in tumor‐draining lymph nodes and in degranulating CD8+ cells, suggesting the amplification of the immune response induced by PDT. Vaccines consisting of SCCVII cells treated with SL052‐PDT in vitro were effective in reducing growth of established subcutaneous SCCVII tumors. In conclusion, PDT mediated by SL052 is suitable to be integrated with various immunotherapy protocols.
Vitamin D Level in Summer and Winter Related to Measured UVR Exposure and Behavior
Authors: Thieden Elisabeth , Philipsen Peter A. , Heydenreich Jakob , Wulf Hans Christian
Published: August 2009

The influence of the summer UVR exposure on serum‐25‐hydroxyvitamin D (25(OH)D) in late summer and winter was investigated in an open study on 25 healthy, adult volunteers. The UVR exposure dose in standard erythema dose (SED) was monitored continuously during a summer season with personal, electronic wristwatch UVR dosimeters and sun exposure diaries. Constitutive and facultative skin pigmentation was measured in September. 25(OH)D was measured in September and February and was in mean 82 nmol/L ± 25 (mean ± SD) in September and 56 nmol/L ± 19 (mean ± SD) in February. The received cumulative UVR dose measured during a mean of 121 days was 156 SED ± 159 (mean ± SD). The following UVR exposure parameters correlated with 25(OH)D in September and February, respectively: (1) The cumulative UVR dose (r = 0.53; P < 0.01) and (r = 0.43; P = 0.03); (2) Mean daily hours with UVR measurements monitored by the dosimeter (r = 0.64, P = 0.001) and (r = 0.53; P = 0.007); (3) Days “with sun‐exposed upper body” (r = 0.58, P = 0.003) and (r = 0.50; P = 0.01); (4) Facultative pigmentation (r = 0.47; P < 0.02) and (r = 0.7; P < 0.001); (5) Constitutive pigmentation (r = 0.06, n.s.) and (r = 0.43, P = 0.03). Neither days “sunbathing” nor days with “sunscreen applied” correlated with 25(OH)D. The fall in 25(OH)D during winter was dependent on the entry value.
Photosensitized Effects of Rose Bengal on Structure and Function of Lens Protein “Alpha‐Crystallin”
Authors: Youssef Tareq , Kassem Mohamed , Abdella Tarek , Harith Mohamed A. , Lenci Francesco
Published: August 2009

The conformational changes of the bovine lens protein “α‐crystallin” have been investigated in the presence of the photosensitizer Rose Bengal (RB), in the dark as well as after visible light irradiation. Absorption and fluorescence emission spectra of RB [5 × 10−6 m] and Fourier transform‐IR spectra of α‐crystallin [5 mg mL−1] were significantly altered upon RB α‐crystallin complex formation. RB was found to bind to α‐crystallin in a molecular pocket characterized by a low polarity, with Trp most likely involved in this interaction. The binding constant (Kb) has been estimated to be of the order of 2.5 (mg/mL)−1. The intrinsic fluorescence of α‐crystallin was quenched through both dynamic and static mechanisms. Light‐induced photosensitized effects showed structural modifications in α‐crystallin, including tertiary and secondary structure (an increase in unordered structure) alterations. Notwithstanding those photoinduced structural variations detected in α‐crystallin when complexed with RB, the protein still retains its ability to play the role of chaperone for β‐crystallin.
Photoproducts Formed in the Photoyellowing of Collagen in the Presence of a Fluorescent Whitening Agent
Authors: Dyer Jolon M. , Clerens Stefan , Cornellison Charisa D. , Murphy Chris J. , Maurdev George , Millington Keith R.
Published: August 2009

Fibrous proteins discolor on exposure to the UV component of sunlight. This effect is exacerbated in the presence of fluorescent whitening agents (FWAs), which are often applied to textiles to improve product brightness. Tryptophan photoproducts have been identified as significant contributors to protein photoyellowing; however, the role of non–tryptophan‐derived chromophores is less clear. In this study bovine collagen, containing no tryptophan residues, was irradiated in the presence and absence of the stilbene‐derived FWA, 4,4′‐bis(2‐sulfostyryl)biphenyl (DSBP) and photoproducts were identified using mass spectrometry. Photoyellowing was found to be dependent on the presence of the FWA, attributed to amplified generation of reactive oxygen species (ROS), particularly hydroxyl radicals and peroxynitrite. Four key proteinaceous photomodifications contributing directly to photoyellowing were located in irradiated collagen pretreated with DSBP, namely dopa, nitrophenylalanine, nitrotyrosine and nitrohistidine. This represents the first direct characterization of the three nitrated residues in the photoyellowing of an isolated fibrous protein, and implicates the ROS, peroxynitrite, as a key contributor to protein photoyellowing. Direct oxidative modification of the FWA itself was also observed. This study demonstrates that, even in the absence of tryptophan residues, significant photomodification of protein residues leading to chromophore formation occurs in the presence of an FWA.
Sideroblastic changes of the bone marrow can be predicted by the erythrogram of peripheral blood
Authors: ROVÓ A. , STÜSSI G. , MEYER‐MONARD S. , FAVRE G. , TSAKIRIS D. , HEIM D. , HALTER J. , ARBER C. , PASSWEG J. , GRATWOHL A. , TICHELLI A.
Published: August 2009

The diagnosis of sideroblastic anemia is based on bone marrow aspiration, and the detection of ring sideroblasts (RS) in iron staining. The finding of laboratory parameters to approach this diagnosis still remains a great challenge. In this study, we analyzed the value of a specific erythrogram pattern from peripheral blood, produced by the ADVIA®120 cell counter, to predict sideroblastic changes in the bone marrow. In a two step‐design study, we first showed that 32/38 consecutive patients reporting ≥15% RS had such a pattern in the erythrogram. In the second step, we prospectively identified over a period of 32 months 21 patients with this typical erythrogram; 20/21 had ≥15% RS in the bone marrow. Hence, by this validation, we confirm that the erythrogram is highly predictive of RS in the bone marrow. The interpretation of the erythrogram should become daily practice in hematology to improve the efficacy to detect sideroblastic changes.
Effects of 4‐Aminopyridine on Cloned hERG Channels Expressed in Mammalian Cells
Authors: Renganathan Muthukrishnan , Sidach Serguei , Blight Andrew R.
Published: August 2009

Introduction.  Non‐clinical evaluation of a medication's potential to induce cardiac toxicity is recommended by regulatory agencies. 4‐Aminopyridine (fampridine) is a potassium channel blocker with the demonstrated ability to improve walking ability in patients with multiple sclerosis. We evaluated the in vitro effects of 4‐aminopyridine on the human ether‐à‐go‐go‐related gene (hERG) channel current, since hERG current inhibition is associated with QT interval prolongation—a precursor to torsade de pointes (TdP).

Methods.  4‐Aminopyridine was evaluated in concentrations ranging from 0.1 mM to 30 mM in human embryonic kidney 293 cells stably transfected with the hERG gene; terfenadine 60 nM was used as a positive control.

Results and Discussion.  We observed concentration‐dependent inhibition of hERG current with 4‐aminopyridine doses between 0.3 and 30 mM. The concentration of 3.8 mM resulting in 50% inhibition (IC50) is approximately three orders of magnitude higher than expected therapeutic plasma concentrations, suggesting 4‐aminopyridine has low potential for prolonging QT interval or inducing TdP.
Region‐specific changes in sympathetic nerve activity in angiotensin II–salt hypertension in the rat
Authors: Osborn John W. , Fink Gregory D.
Published: August 2009

It is now well accepted that many forms of experimental hypertension and human essential hypertension are caused by increased activity of the sympathetic nervous system. However, the role of region‐specific changes in sympathetic nerve activity (SNA) in the pathogenesis of hypertension has been difficult to determine because methods for chronic measurement of SNA in conscious animals have not been available. We have recently combined indirect, and continuous and chronic direct, assessment of region‐specific SNA to characterize hypertension produced by administration of angiotensin II (Ang II) to rats consuming a high‐salt diet (Ang II–salt hypertension). Angiotensin II increases whole‐body noradrenaline (NA) spillover and depressor responses to ganglionic blockade in rats consuming a high‐salt diet, but not in rats on a normal‐salt diet. Despite this evidence for increased ‘whole‐body SNA’ in Ang II–salt hypertensive rats, renal SNA is decreased in this model and renal denervation does not attenuate the steady‐state level of arterial pressure. In addition, neither lumbar SNA, which largely targets skeletal muscle, nor hindlimb NA spillover is changed from control levels in Ang II–salt hypertensive rats. However, surgical denervation of the splanchnic vascular bed attenuates/abolishes the increase in arterial pressure and total peripheral resistance, as well as the decrease in vascular capacitance, observed in Ang II–salt hypertensive rats. We hypothesize that the ‘sympathetic signature’ of Ang II–salt hypertension is characterized by increased splanchnic SNA, no change in skeletal muscle SNA and decreased renal SNA, and this sympathetic signature creates unique haemodynamic changes capable of producing sustained hypertension.
Effect of Geometry on the Conjugate Heat Transfer of Wall Jet Flow Over a Backward-Facing Step
Authors: Kanna P. Rajesh , Das Manab Kumar
Published: August 2009

Conjugate heat transfer study of a backward-facing step cooled by a two-dimensional laminar incompressible wall jet has been carried out. The study is performed to find the isotherm patterns, conjugate interface temperature, local Nusselt number and average Nusselt number by varying the geometry of the solid slab. Different step length, step height, and slab thickness are considered for conjugate heat transfer study.
Convective Heat Transfer for Water-Based Alumina Nanofluids in a Single 1.02-mm Tube
Authors: Lai W. Y. , Vinod S. , Phelan P. E. , Prasher Ravi
Published: August 2009

Nanofluids are colloidal solutions, which contain a small volume fraction of suspended submicron particles or fibers in heat transfer liquids such as water or glycol mixtures. Compared with the base fluid, numerous experiments have generally indicated an increase in effective thermal conductivity and a strong temperature dependence of the static effective thermal conductivity. However, in practical applications, a heat conduction mechanism may not be sufficient for cooling high heat dissipation devices such as microelectronics or powerful optical equipment. Thus, thermal performance under convective heat transfer conditions becomes of primary interest. We report here the heat transfer coefficient h in both developing and fully developed regions by using water-based alumina nanofluids. Our experimental test section consists of a single 1.02-mm diameter stainless steel tube, which is electrically heated to provide a constant wall heat flux. Both pressure drop and temperature differences are measured, but mostly here we report our h measurements under laminar flow conditions. An extensive characterization of the nanofluid samples, including pH, electrical conductivity, particle sizing, and zeta potential, is also documented. The measured h values for nanofluids are generally higher than those for pure water. In the developing region, this can be at least partially explained by Pr number effects.
Cooling Performance of Arrays of Vibrating Cantilevers
Authors: Kimber Mark , Garimella Suresh V.
Published: August 2009

Piezoelectric fans are vibrating cantilevers actuated by a piezoelectric material and can provide heat transfer enhancement while consuming little power. Past research has focused on feasibility and performance characterization of a single fan, while arrays of such fans, which have important practical applications, have not been widely studied. This paper investigates the heat transfer achieved using arrays of cantilevers vibrating in their first resonant mode. This is accomplished by determining the local convection coefficients due to the two piezoelectric fans mounted near a constant heat flux surface using infrared thermal imaging. The heat transfer performance is quantified over a wide range of operating conditions, including vibration amplitude (7.5–10 mm), distance from heat source (0.01–2 times the fan amplitude), and pitch between fans (0.5–4 times the amplitude). The convection patterns observed are strongly dependent on the fan pitch, with the behavior resembling a single fan for small fan pitch and two isolated fans at a large pitch. The area-averaged thermal performance of the fan array is superior to that of a single fan, and correlations are developed to describe this enhancement in terms of the governing parameters. The best thermal performance is obtained when the fan pitch is 1.5 times its vibration amplitude.
A Thermal Stability Criterion for Heat Conduction in Multilayer Composite Solids
Authors: Yang Bingen , Shi Hang
Published: August 2009

Excessive heat generation within a body can cause unbounded temperature or thermal instability. In this work, a new stability test is established for heat conduction in one-dimensional multilayer composite solids that have internal heat generation at a rate proportional to the interior temperature. In the development, a spatial state formulation in the Laplace transform domain and a root locus analysis yield a stability criterion. This criterion gives an upper bound of heat source for thermal stability and relates the degree of excessive heat production to the number of unstable (positive) eigenvalues. The proposed stability test does not need any information on system eigenvalues, requests minimum computational effort, and is applicable to composites with thermal resistance at layer interfaces and bodies with nonuniformly distributed parameters. The convenience and efficiency of the stability test are demonstrated in three numerical examples.
Periodic Fluid Flow and Heat Transfer in a Square Cavity Due to an Insulated or Isothermal Rotating Cylinder
Authors: Shih Y.-C. , Khodadadi J. M. , Weng K.-H. , Ahmed A.
Published: August 2009

The periodic state of laminar flow and heat transfer due to an insulated or isothermal rotating cylinder object in a square cavity is investigated computationally. A finite-volume-based computational methodology utilizing primitive variables is used. Various rotating objects (circle, square, and equilateral triangle) with different sizes are placed in the middle of a square cavity. A combination of a fixed computational grid and a sliding mesh was utilized for the square and triangle shapes. For the insulated and isothermal objects, the cavity is maintained as differentially heated and isothermal enclosures, respectively. Natural convection heat transfer is neglected. For a given shape of the object and a constant angular velocity, a range of rotating Reynolds numbers are covered for a Pr=5 fluid. The Reynolds numbers were selected so that the flow fields are not generally affected by the Taylor instabilities (Ta<1750). The periodic flow field, the interaction of the rotating objects with the recirculating vortices at the four corners, and the periodic channeling effect of the traversing vertices are clearly elucidated. The simulations of the dynamic flow fields were confirmed against experimental data obtained by particle image velocimetry. The corresponding thermal fields in relation to the evolving flow patterns and the skewness of the temperature contours in comparison to the conduction-only case were discussed. The skewness is observed to become more marked as the Reynolds number is lowered. Transient variations of the average Nusselt numbers of the respective systems show that for high Re numbers, a quasiperiodic behavior due to the onset of the Taylor instabilities is dominant, whereas for low Re numbers, periodicity of the system is clearly observed. Time-integrated average Nusselt numbers of the insulated and isothermal object systems were correlated with the rotational Reynolds number and shape of the object. For high Re numbers, the performance of the system is independent of the shape of the object. On the other hand, with lowering of the hydraulic diameter (i.e., bigger objects), the triangle and the circle exhibit the highest and lowest heat transfers, respectively. High intensity of the periodic channeling and not its frequency is identified as the cause of the observed enhancement.
Determination of Unknown Coefficients in Parabolic Equations
Authors: Zhou Shiping , Cui Minggen
Published: August 2009

In this paper, we consider solving for a coefficient inverse problem in the parabolic equation. A new numerical method for the identification of the space-dependent coefficient is developed in a reproducing kernel space. The coefficients can be solved by a lower triangle linear system. Some numerical experiments are presented to show the efficiency of the proposed method.
Numerical Prediction of Cavitation in Model Pump
Authors: Shukla Shyam N. , Kshirsagar Jagadish
Published: August 2009

It is known that the pumps create suction and hence suck fluid. When a volume of liquid is subjected to a sufficiently low pressure, it may change its phase from liquid to gaseous resulting in vapor bubbles. The process of formation of vapour bubble in an area where the liquid pressure falls to the vapour pressure, and the subsequent collapse of those bubbles when they enter a region of higher pressure is referred to as cavitation. In pump industry, NPSH (net positive suction head) is the term frequently used to check cavitation condition. It is an absolute energy available above vapour pressure. A pump designer uses empirical relation to estimate cavitations performance of the impeller in absence of experimental test facility. One such correlation exists for optimizing the eye diameter of the pump. Based on the inlet flow velocity, rotational speed, the correlation brings out NPSHr value for different eye diameter. The trend shows that the NPSHr is higher with lower eye diameter; it continues to drop down with increasing eye diameter reaching lowest value and again increases gradually with further increase of eye diameter. An effort was made to give a scientific basis for the empirical correlation using Computational Fluid Dynamics approach. The present paper describes a case study wherein cavitation performance of the pump is predicted empirically. The pump is tested to check cavitation performance. These results are validated using commercially available CFD software for 3% head drop. Further to this, CFD code is used to check the variation of cavitation performance in respect to change of eye diameter. The paper in short presents three approaches, empirical, experimental and numerical simulation.
Transfer of Modelling Concepts for Flow and Transport Processes in Porous Media From Subsurface Systems to Biological Tissues
Authors: Helmig Rainer , Darcis Melanie , Class Holger
Published: August 2009

Flow and transport phenomena in porous media are the governing processes in many natural and industrial systems. For the numerical description of these systems their multiscale behavior plays an important role. In one part of the system highly complex flow and transport processes may necessitate an examination of the processes on a fine spatial and temporal scale, while in other parts of the system, physically simpler processes may be examined on coarser scales. The heterogeneous structure of the porous medium itself also shows a high dependence on the spatial scale. Whereas different kinds of heterogeneities predominate on different scales. For these multiscale problems, many modeling concepts have been developed over the last decades. In this presentation, we aim to develop and to discuss the transfer of available modeling concepts for geological and industrial systems to biological tissues. In a comparison study, the similarities of both systems will be presented. First simulation results will show the opportunities of the described model transfer. In this context, we will also point out the required assumptions and the difficulties resulting from such a modeling concept transfer.
Seamless Tool Integration for Solder Joint Qualifications
Authors: Qian Zhengfang , Wu Xin
Published: August 2009

This paper presents an approach and its demonstration for seamless tool integration for the virtual qualification and reliability prediction of solder joints of surface mounted electronic components on a populated circuit board. Starting from software called Surface Evolver, it can be used to realistically reproduce complicated geometry profiles of solder joints with various lead frames and pad specifications. User routines have been developed under ANSYS platform for automatic geometry transfer from the Surface Evolver and mesh regeneration of the solder joints inside ANSYS, as demonstrated in this paper. Moreover, a number of electronic packages with their solder joints on a typical printed circuit board (PCB) were also regenerated with parametric capability. Finite element analyses (FEAs) with proper set-up of materials, boundary conditions, and constitutive models were performed automatically by hitting one-button to go. Reliability prediction of solder joints and the failure rate of electronic components can be predicted based on failure criteria and test data implemented. An in-house tool was developed for the whole procedure of solder joint qualification and reliability assessment from deterministic to statistical aspects, including the evaluation of defect impacts.
Error Estimates for Reduced Order POD Models of Navier-Stokes Equations
Authors: Ravindran S. S.
Published: August 2009

Reduced order modeling for the purpose of constructing a low dimensional model from high dimensional or infinite dimensional model has important applications in science and engineering such as fast model evaluations and optimization/control. A popular method for constructing reduced-order model is based on finding a suitable low dimensional basis by proper orthogonal decomposition (POD) and forming a model by Galerkin projection of the infinite dimensional model onto the basis. In this paper, we will discuss error estimates for Galerkin proper orthogonal decomposition method for an unsteady nonlinear coupled partial differential equations arising in viscous incompressible flows. A specific finite element in space and finite difference in time discretization scheme will be discussed.
High Dimensional Harmonic Balance Analysis for Dynamic Piecewise Aeroelastic Systems
Authors: Liu Liping , Dowell Earl H.
Published: August 2009

This paper describes the extension and application of a novel solution method for the periodic nonlinear oscillations of an aeroelastic system. This solution method is a very attractive alternative to time marching algorithms in that it is much faster and may track unstable as well as stable limit cycles. The method is employed to analyze the nonlinear aeroelastic response of a two dimensional airfoil including a control surface with freeplay placed in an incompressible flow. The mathematical model for this piecewise aeroelastic system is initially formulated as a set of first order ordinary differential equations. A frequency domain solution for the limit cycle oscillations is derived by a novel high dimensional harmonic balance (HDHB) method. By an inverse Fourier transformation, the system in the frequency domain is then converted into the time domain. Finally, the airfoil motions are obtained by solving the system in the time domain for only one period of limit cycle oscillation. This process can be easily implemented into computer programs without going through the complex algebraic manipulations for the nonlinearities typical of a more conventional harmonic balance solution method. The solutions found using this new HDHB method have been shown to be the same as those found using a more traditional time marching (e.g. Runge-Kutta) approach and also a conventional harmonic balance approach in the frequency domain with a considerable computational time saving.
Finite Element Modeling of a Diffusion-Controlled Phase Transformation in Thin Film
Authors: Asle-Zaeem Mohsen , Mesarovic Sinisa Dj.
Published: August 2009

We derive and implement a finite element (FE) model for stress-mediated diffusion and phase transformation in thin films. The partial differential equations governing diffusion and mechanical equilibrium are of different order. To ensure uniform convergence of the FE method, the continuity class of respective interpolation functions must be different. We test our implementation on a 1D problem and demonstrate the validity of the approach.
Humanoid Face Utilizing Rotary Actuator and Piezoelectric Sensors
Authors: Tadesse Yonas , Priya Shashank
Published: August 2009

Mimicking facial structure for a robotic head is a challenging issue and requires information on design and control of muscle actuation, architecture of the linkages between actuation points within skin, and deformation matrix with respect to global coordinates for a specific expression. This manuscript presents: (1) a functional relationship between deformation vector of facial control points and actuator parameter, skin elasticity and angular position of actuator. The actuation method is applicable to any rotary actuator technology utilized for facial expressions and takes into account the skin stiffness; (2) a prototype robotic head with embedded sensor to enhance interaction ability of humanoids; and (3) characterization of various facial expressions on a prototype robotic face.
Phonon Thermal Transport in Bulk and Nanostructured Materials From First Principles
Authors: Broido D. A. , Mingo Natalio , Stewart Derek
Published: August 2009

Current theories of phonon thermal transport in nanomaterials are often based on highly parametrized approximations or on purely classical molecular dynamics calculations. We present a rigorous theoretical approach to accurately describe phonon thermal transport in bulk and nanostructured materials. This technique is based on Boltzmann and non-equilibrium Green’s function calculations of thermal transport, and employs ab-initio calculations of harmonic and anharmonic interatomic force constants using density functional perturbation theory. The approach has been applied to bulk semiconductors, where excellent agreement is obtained between the calculated and measured intrinsic lattice thermal conductivities of silicon and germanium without any adjustable parameters. In addition, ab initio calculations of phonon thermal conductance in carbon nanotubes with isolated Stone-Wales and substitutional defects are presented and discussed.
Advanced Finite Element Formulation for Piezoelectric Smart Shell Structures Under Consideration of Geometrical Nonlinearity
Authors: Schulz Katrin , Klinkel Sven , Wagner Werner
Published: August 2009

A geometrically nonlinear highly accurate finite element formulation to analyze piezoelectric shell problems is presented. The formulation is based on the mixed field variational principle of Hu-Washizu including the independent fields displacements, electric potential, strains, electric field, mechanical stresses and dielectric displacements. The normal zero stress condition and the normal zero dielectric displacement condition for shells are enforced by the independent resultant stress and resultant dielectric displacement fields. The arbitrary reference surface of the shell is modeled with a four node element. Each node possesses six mechanical degrees of freedom, three displacements and three rotations, and one electrical degree of freedom, which is the difference of the electric potential through the shell thickness. The developed shell element fulfills the patchtests and is able to model arbitrary curved shell structures. Some numerical examples demonstrate the applicability of the present shell element for piezoelectric systems and integrated piezoelectric structures.