bluuebunny/crossref_metadata_2025 huggingface dataset:
Impact of mild to moderate elevations of alanine aminotransferase on liver stiffness measurement in chronic hepatitis B patients during antiviral therapy
Authors: Yan Li‐Bo , Zhu Xia , Bai Lang , Liang Ling‐Bo , Chen En‐Qiang , Du Ling‐Yao , Wang Li‐Chun , Chen Li‐Yu , Tang Hong
Published: June 2012

Aim:  The accuracy of liver stiffness measurement (LSM) in the diagnosis of liver fibrosis is affected by elevated serum alanine aminotransferase (ALT) levels. The aim of this study was to assess the impact of mild to moderate elevations of ALT on LSM in patients with chronic hepatitis B (CHB) during antiviral therapy.

Methods:  A total of 58 CHB patients with their ALT levels falling into the range of ×2 to ×10 the upper limit of normal (ULN) were recruited. ALT and LSM values were periodically assessed at baseline and 12, 24 and 48 weeks.

Results:  The median ALT levels were 153.5 (76–544), 50.5 (11–475), 36.5 (9–265) and 30 (12–239) IU/L at baseline and 12, 24 and 48 weeks, respectively. The corresponding median value of LSM was 8.8 (3.2–47.3), 6.15 (3.2–31.2), 5.9 (3.1–29.1) and 5.5 (2.8–21.5) kpa. However, after the ALT levels were normalized by the treatment, the values of LSM did not vary significantly (6.1 [3.0–17.7] vs 5.25 [2.8–21.5] kpa, P = 0.381). Pretreatment fibrosis stages of liver biopsies corresponded with LSM after ALT normalization rather than baseline LSM (F0–1, 12/27 vs 23/25, P < 0.001).

Conclusion:  The LSM values decreased in parallel with the decline in ALT levels in CHB patients with mild to moderate elevation of ALT. LSM became more accurate when applied to document the liver fibrosis or cirrhosis in CHB patients after the elevated ALT level has been treated to normal level.
Regional Entrepreneurial Heritage in a Socialist and a Postsocialist Economy
Authors: Wyrwich Michael
Published: June 2012

abstract

Regions have a distinct entrepreneurial heritage, understood as a historical tradition in entrepreneurial culture. The persistence of that heritage in the former German Democratic Republic (GDR) is examined across severe ruptures in economic development. In this article, I argue that regional differences in private‐sector activities under socialism—a system that was hostile toward entrepreneurs—reflect strong entrepreneurial orientations of local populations and regional cultures of entrepreneurship that were presocialist in origin. The empirical analysis suggests that an “entrepreneurial residual,” left over from the socialist experiment, positively affected startup activity after the transformation of the GDR back to a market economy. The results show that an entrepreneurial culture is an important regional resource that endures.
Efficacy and safety of sitagliptin monotherapy and combination therapy in Japanese type 2 diabetes patients
Authors: Kubota Akira , Maeda Hajime , Kanamori Akira , Matoba Kiyokazu , Jin Yasuyuki , Minagawa Fuyuki , Obana Mitsuo , Iemitsu Kotaro , Ito Shogo , Amamiya Hikaru , Kaneshiro Mizuki , Takai Masahiko , Kaneshige Hideaki , Hoshino Kazuhiko , Ishikawa Masashi , Minami Nobuaki , Takuma Tetsuro , Sasai Nobuo , Aoyagi Sachio , Kawata Takehiro , Mokubo Atsuko , Takeda Hiroshi , Honda Shin , Machimura Hideo , Motomiya Tetsuya , Waseda Manabu , Naka Yoshikazu , Tanaka Yasushi , Terauchi Yasuo , Matsuba Ikuro
Published: June 2012

(J Diabetes Invest, doi: 10.1111/j.2040‐1124.2012.00221.x, 2012)

Aims/Introduction:  To determine the efficacy and safety of sitagliptin monotherapy and combination therapy in Japanese type 2 diabetes patients after 3 months’ therapy.

Materials and Methods:  A retrospective, observational study of 741 type 2 diabetes patients was carried out; 110 received sitagliptin monotherapy, and 631 received combination therapy with sitagliptin when other oral medications were insufficient. The primary outcome measure was glycated hemoglobin (HbA1c) measured at 0, 4 and 12 weeks of sitagliptin therapy.

Results:  In the monotherapy and combination therapy groups, HbA1c decreased significantly after 12 weeks. Target HbA1c (<7%) was achieved in 39.1% overall. On logistic regression analysis, baseline HbA1c was the strongest contributing factor for achieving target HbA1c; baseline body mass index and duration of diabetes were also significant factors. A total of 82 patients (11%) were unresponsive to sitagliptin. These patients’ baseline body mass index was significantly higher and their baseline HbA1c was significantly lower than those of patients who responded to sitagliptin. The most commonly co‐administered drugs were sulfonylureas (508 patients). In these patients, the dose of sulfonylurea decreased with time. In 66 patients whose sulfonylurea dosage was reduced when sitagliptin was started, HbA1c and bodyweight decreased significantly after 12 weeks. A total of 24 patients receiving sulfonylureas had mild hypoglycemia, but none discontinued sitagliptin.

Conclusions:  Sitagliptin was effective and safe as both monotherapy and combination therapy in Japanese type 2 diabetes patients. When sulfonylureas were ineffective, sitagliptin improved glycemic control. In patients whose sulfonylurea dose was reduced at the start of sitagliptin, blood glucose improved and bodyweight decreased after 12 weeks.
Efficacy of liraglutide therapy in Japanese type 2 diabetic patients insufficiently controlled with basal‐supported oral therapy
Authors: Takahara Mitsuyoshi , Shiraiwa Toshihiko , Ohtoshi Kentaro , Kaneto Hideaki , Katakami Naoto , Matsuoka Taka‐aki , Shimomura Iichiro
Published: June 2012

(J Diabetes Invest, doi: 10.1111/j.2040‐1124.2012.00223.x, 2012)

Aims/Introduction:  We assessed the efficacy of liraglutide therapy in Japanese type 2 diabetic patients insufficiently controlled with basal‐supported oral therapy (BOT).

Materials and Methods:  We retrospectively analyzed the data of 37 patients who had postprandial hyperglycemia (≥10.0 mmol/L) with BOT (long‐acting insulin plus glimepiride) with their insulin titrated enough to keep preprandial glycemia <7.2 mmol/L, and who had their treatment changed to liraglutide monotherapy, with the subsequent addition of glimepiride, when required. Those who achieved the glycemic target at all points (preprandial glycemia <7.2 mmol/L and postprandial glycemia <10.0 mmol/L) were regarded as responders and the efficacy of liraglutide therapy was assessed. We also explored the predictive clinical characteristics associated with its efficacy.

Results:  Daily doses of insulin and glimepiride with BOT were 14 ± 9 units and 1.5 ± 0.9 mg, respectively. After the change to liraglutide therapy, 37% of the patients appeared to be responders to the therapy, whereas 12% had their glycemic control rather deteriorated. Efficacy of liraglutide therapy was significantly associated with baseline insulin dosage and post‐breakfast glycemia with BOT. The C‐statistic of the model was calculated to be 0.90.

Conclusions:  There were responders and non‐responders to liraglutide therapy in Japanese BOT failures. It is likely that baseline insulin dosage and post‐breakfast glycemia with BOT are clinically useful indicators for the efficacy of liraglutide therapy.
Introduction of glycated albumin measurement for all blood donors and the prevalence of a high glycated albumin level in Japan
Authors: Araki Takeshi , Ishikawa Yoshihide , Okazaki Hitoshi , Tani Yoshihiko , Toyooka Shigetake , Satake Masahiro , Miwa Umeo , Tadokoro Kenji ,   for the Japanese Red Cross GA Research Group
Published: June 2012

(J Diabetes Invest, doi: 10.1111/j.2040‐1124.2012.00224.x, 2012)

Aims/Introduction:  The Japanese Red Cross Society introduced measurement of glycated albumin (GA) for all blood donors as a glycemic control marker. The GA levels were examined by sex and age.

Materials and Methods:  GA was measured in 3.14 million blood donors who donated between April 2009 and March 2010. For the reference range for GA, values that were three times the reference range for glycated hemoglobin (Japan Diabetes Society value) were used. All donors were notified of their GA levels. For repeat donors, a comparison was made between the GA levels at the first and second donations to verify the GA change after notification.

Results:  The mean GA was significantly lower in males than in females in donors aged <60 years. The mean GAs of both sexes increased with age and reached the same level of 14.8% in their 60s. The percentage of donors with prediabetes/diabetes (GA ≥16.5%) was 2.8% in males and 2.3% in females. In the normal high group (15.6% ≤ GA < 16.5%), the mean GA at the second donation was lower by 0.20% than at the first donation. In 42.4% of these donors, GA decreased to the normal range at the second donation.

Conclusions:  Overall, 2.7% of otherwise healthy Japanese blood donors had a high GA (GA ≥16.5%). Donor blood screening for GA represents an effective measure to identify people at risk of diabetes. The decrease in the GA level after GA notification might indicate the potential usefulness of this strategy to improve glycemic control among people with high GA.
No Meal without Ugali? Social Significance of Food and Consumption in a Tanzanian Village
Authors: Ohna Ingrid , Kaarhus Randi , Kinabo Joyce
Published: June 2012

Employing diet and cuisine as analytical concepts, this article focuses on cultural categories and social meanings of food in Malinzanga village in southern Tanzania. Through analyses of access to foodstuffs, sequence of meals, and methods of preparation, the article shows how key elements in a basic meal structure are used locally to characterize and classify people—both in terms of ethnic group membership and in terms of respectable social status versus “disgraceful” poverty as perceived locally. The population in Malinzanga includes four ethnic groups: two pastoralist groups, Mang'ati and Masai, and two agriculturalist groups, Hehe and Bena. It is argued that patterns of food consumption among the people in Malinzanga cannot be attributed to access to resources and purchasing power alone. Food consumption can also be seen as a means of expression of what Malinzanga villagers think about own identities, status, and social distinctions.
Basket Cases and Breadbaskets: Sacred Rice and Agricultural Development in PostcolonialAfrica
Authors: Davidson Joanna
Published: June 2012

Based on ethnographic research among ruralDiola inGuinea‐Bissau, I provide a broad view of the history and interpenetration of rice in social, political, religious, and ecological domains, while chronicling the current difficulties of residents in this region who are no longer able to grow enough of it. These farmers' experiences are unfolding at a time of revitalized attention to agricultural development inAfrica, particularly under the auspices of theNewGreenRevolution forAfrica. I examine the premises that constitute the resuscitated effort to address the plight ofAfrican farmers. I argue that the totalizing quality of rice inDiola and other rice‐cultivating societies requires a development approach that takes into account dimensions of agrarian life not encapsulated by the high‐modernist and antipolitical orientation of theNewGreenRevolution forAfrica.
Playing the Market: How the Cashew “Commodityscape” Is Redefining Guinea‐Bissau's Countryside
Authors: Lundy Brandon D.
Published: June 2012

Guinea‐Bissau's political ecology of the 1980s led to cashews overtaking all other exports as a generator of national revenue. Through ethnographic methodology, this paper examines the cashew commodityscape illustrated through an examination of several villages in southern Guinea‐Bissau. This research addresses how household livelihood strategies are fashioned as a result of necessity, opportunity, and negotiations with local, regional, and global economies. A majority of the local population in the research site was involved in cashew pomiculture in 2007 when the global demand and purchase price was low. By 2010, the price paid by Indian wholesalers rebounded with even further integration of this commodity into the natural and cultural landscape. This paper finds that cashews are playing a significant role in the environmental, economic, and cultural spheres. This local articulation of a global phenomenon demonstrates the potential pitfalls and benefits of meeting very specific global needs.
Perceptions of Climate Variability and Pest–Disease Incidence on Crops and Adaptive Forest–Agricultural Practices
Authors: Mala William A. , Geldenhuys Coert J. , Prabhu Ravi
Published: June 2012

The article examines the influence of local perceptions of climate variability and pest–disease incidence on crops and its management and on adaptive forest–agricultural practices. The study was conducted in the humid forest of Southern Cameroon along a resource use intensification and population gradient using a semi‐structured questionnaire administrated to farmers. The results showed that the level of severity of crops–pests incidence was perceived as high, with an increase over the past 15 years. A high incidence of pests–diseases was perceived on yield/income of cocoa, cassava, and groundnuts. The results indicated that each crop has its management practices of pests–diseases both at the crop and land use level. The farmers respond positively to their perception of climate variability by anticipating cropping practices, by harvesting earlier or later, and by adapting strategies of pests–diseases with crops and land use practices that affect the sustainability of forest–agriculture.
“You Can't Eat Money When You Are Hungry”: Campesinos, Manatee Hunting, and Environmental Regret in Veracruz, Mexico
Authors: Smith‐Cavros Eileen M. , Duluc‐Silva Sylvia , Rodriguez Maria del Carmen , Ortiz Ponciano , Keith Edward O.
Published: June 2012

Self‐identified campesinos were interviewed in rural Veracruz, Mexico as part of this qualitative research study. Participants had firsthand historical knowledge about hunting the Antillean manatee (Trichechus manatus manatus) or about preparing the manatee for human consumption. The lagoon ecosystem that surrounds the area is greatly degraded and its contemporary inhabitants speak of the past with a great deal of wistfulness and a sense of loss characterized as “environmental regret.” The study examines the evolving local environmental and cultural practices, attitudes, and circumstances.
Development, Land Use, and Collective Trauma: The Marcellus Shale Gas Boom in Rural Pennsylvania
Authors: Perry Simona L.
Published: June 2012

This article describes a place and people undergoing rapid transition using some of the preliminary findings from two years of ongoing ethnographic field work. Through exploring what ethnographic evidence is revealing concerning the impacts of Marcellus shale gas development in Bradford County, in Northeastern Pennsylvania, I illustrate the ways that rapid social and economic change processes are impacting daily lives and community dynamics in one traditionally agricultural and rural place. I provide a broad overview of the social history and current social dynamics in order to understand the significance of the short‐term changes agricultural landowners and other local residents have witnessed and experienced. I discuss some of the most significant short‐term changes in quality of life as seen by a small group of agricultural landowners, in relation to the cultural significance of place, home, and family, and what this tells us about the sociocultural and psychological impacts of rapid energy development. Finally, I comment on what my ethnographic data show so far with regard to the short‐ and long‐term individual and collective impacts being experienced in this one community.
Pulmonary vascular distensibility predicts aerobic capacity in healthy individuals
Authors: Lalande Sophie , Yerly Patrick , Faoro Vitalie , Naeije Robert
Published: June 2012

Key points

Pulmonary transit of agitated contrast (PTAC) occurs during exercise in healthy individuals.

It has been suggested that positive PTAC reflects a greater pulmonary vascular reserve, allowing for the right ventricle to operate at a decreased afterload at high levels of exercise.

In this study, we determined whether individuals with highest maximal aerobic capacity have the greatest pulmonary vascular distensibility, highest PTAC and greatest increase in the capillary blood component of lung diffusing capacity during exercise.

We observed that individuals with highest maximal aerobic capacity have a more distensible pulmonary circulation as observed through greater pulmonary vascular distensibility, greater pulmonary capillary blood volume, and lowest pulmonary vascular resistance at maximal exercise.

Pulmonary vascular distensibility predicts aerobic capacity in healthy individuals.

Abstract  It has been suggested that shallow slopes of mean pulmonary artery pressure (MPPA)–cardiac output () relationships and pulmonary transit of agitated contrast during exercise may be associated with a higher maximal aerobic capacity (). If so, individuals with a higher could also exhibit a higher pulmonary vascular distensibility and increased pulmonary capillary blood volume during exercise. Exercise stress echocardiography was performed with repetitive injections of agitated contrast and measurements of MPPA, and lung diffusing capacities for carbon monoxide (DL,CO) and nitric oxide (DL,NO) in 24 healthy individuals. A pulmonary vascular distensibility coefficient α was mathematically determined from the slight natural curvilinearity of multipoint MPPA– plots. Membrane (Dm) and capillary blood volume (Vc) components of lung diffusing capacity were calculated. Maximal exercise increased MPPA, cardiac index (CI), DL,CO and DL,NO. The slope of the linear best fit of MPPA–CI was 3.2 ± 0.5 mmHg min l−1 m2 and α was 1.1 ± 0.3% mmHg−1. A multivariable analysis showed that higher α and greater Vc independently predicted . All individuals had markedly positive pulmonary transit of agitated contrast at maximal exercise, with increases proportional to increases in pulmonary capillary pressure and Vc. Pulmonary transit of agitated contrast was not related to pulse oximetry arterial oxygen saturation. Therefore, a more distensible pulmonary circulation and a greater pulmonary capillary blood volume are associated with a higher in healthy individuals. Agitated contrast commonly transits through the pulmonary circulation at exercise, in proportion to increased pulmonary capillary pressures.
Contribution of intravascular versus interstitial purines and nitric oxide in the regulation of exercise hyperaemia in humans
Authors: Hellsten Y. , Nyberg M. , Mortensen S. P.
Published: June 2012

Abstract  The regulation of blood flow to skeletal muscle involves a complex interaction between several locally formed vasodilators that are produced both in the skeletal muscle interstitium and intravascularly. The gas nitric oxide (NO) and the purines ATP and adenosine, are potent vasodilators that are formed by multiple cell types and released into the skeletal muscle interstitium and in plasma in response to muscle contraction. Cellular sources of ATP and NO in plasma are erythrocytes and endothelial cells, whereas interstitial sources are skeletal muscle cells and endothelial cells. Adenosine originates primarily from extracellular degradation of ATP. During exercise the concentrations of ATP and adenosine increase markedly in the interstitium with smaller increases occurring in plasma, and thus the interstitial concentration during exercise is severalfold higher than in plasma. The concentration of NO metabolites (NOx) in interstitium and plasma does not change during exercise and is similar in the two compartments. Adenosine and NO have been shown to contribute to exercise hyperaemia whereas the role of ATP remains unclear due to lack of specific purinergic receptor blockers. The relative role of intravascular versus interstitial vasodilators is not known but evidence suggests that both compartments are important. In cardiovascular disease, a reduced capacity to form adenosine in the muscle interstitium may be a contributing factor in increased peripheral vascular resistance.
The hyperaemic response to passive leg movement is dependent on nitric oxide: a new tool to evaluate endothelial nitric oxide function
Authors: Mortensen Stefan P. , Askew Christopher D. , Walker Meegan , Nyberg Michael , Hellsten Ylva
Published: June 2012

Key points

Passive leg movement is associated with a ∼3‐fold increase in blood flow to the leg, but the underlying mechanisms remain unknown.

Passive leg movement increased venous levels of metabolites of nitric oxide (NO) in young subjects, whereas they remained unaltered in the muscle interstitial space. Inhibition of NO synthesis lowered the vasodilatory response to passive leg movement by ∼90%.

The increase in leg blood flow was lower in elderly subjects compared to young subjects and leg blood flow did not increase when passive leg movement was performed by elderly with peripheral artery disease.

The results suggest that the hyperaemia induced by passive leg movement is NO dependent. The hyperaemic response to passive leg movement and to ACh was also assessed in elderly subjects and patients with peripheral artery disease.

Abstract  Passive leg movement is associated with a ∼3‐fold increase in blood flow to the leg but the underlying mechanisms remain unknown. The objective of the present study was to examine the role of nitric oxide (NO) for the hyperaemia observed during passive leg movement. Leg haemodynamics and metabolites of NO production (nitrite and nitrate; NOx) were measured in plasma and muscle interstitial fluid at rest and during passive leg movement with and without inhibition of NO formation in healthy young males. The hyperaemic response to passive leg movement and to ACh was also assessed in elderly subjects and patients with peripheral artery disease. Passive leg movement (60 r.p.m.) increased leg blood flow from 0.3 ± 0.1 to 0.9 ± 0.1 litre min−1 at 20 s and 0.5 ± 0.1 litre min−1 at 3 min (P < 0.05). Mean arterial pressure remained unchanged during the trial. When passive leg movement was performed during inhibition of NO formation (NG‐mono‐methyl‐l‐arginine; 29–52 mg min−1), leg blood flow and vascular conductance were increased after 20 s (P < 0.05) and then returned to baseline levels, despite an increase in arterial pressure (P < 0.05). Passive leg movement increased the femoral venous NOx levels from 35 ± 5 at baseline to 62 ± 11 μmol l−1 during passive leg movement (P < 0.05), whereas muscle interstitial NOx levels remained unchanged. The hyperaemic response to passive leg movement were correlated with the vasodilatation induced by ACh (r2= 0.704, P < 0.001) and with age (r2= 0.612, P < 0.001). Leg blood flow did not increase during passive leg movement in individuals with peripheral arterial disease. These results suggest that the hypaeremia induced by passive leg movement is NO dependent and that the source of NO is likely to be the endothelium. Passive leg movement could therefore be used as a non‐invasive tool to evaluate NO dependent endothelial function of the lower limb.
P2Y2 receptor activation opens pannexin‐1 channels in rat carotid body type II cells: potential role in amplifying the neurotransmitter ATP
Authors: Zhang Min , Piskuric Nikol A. , Vollmer Cathy , Nurse Colin A.
Published: June 2012

Key points

Carotid body (CB) chemoreceptor complexes consist of receptor type I cells, intimately associated with glia‐like type II cells whose function is poorly understood.

We show that type II cells in the rat CB express gap junction‐like proteins, pannexin‐1 (Panx‐1) channels, which form non‐selective pores permeable to ions and large molecules such as ATP, a key CB neurotransmitter.

Activation of purinergic P2Y2 receptors on type II cells led to a rise in intracellular Ca2+, and a prolonged membrane depolarization due to opening of Panx‐1 channels.

In a CB co‐culture model, where purinergic P2X2/3‐expressing petrosal neurones served as a reporter or biosensor of ATP release, we show that selective activation of P2Y2 receptors on type II cells can lead to ATP release via Panx‐1 channels.

We propose that type II cells may function as amplifiers of the neurotransmitter ATP during chemotransduction, via the mechanism of ATP‐induced ATP release.

Abstract  Signal processing in the carotid body (CB) is initiated at receptor glomus (or type I) cells which depolarize and release the excitatory neurotransmitter ATP during chemoexcitation by hypoxia and acid hypercapnia. Glomus cell clusters (GCs) occur in intimate association with glia‐like type II cells which express purinergic P2Y2 receptors (P2Y2Rs) but their function is unclear. Here we immunolocalize the gap junction‐like protein channel pannexin‐1 (Panx‐1) in type II cells and show Panx‐1 mRNA expression in the rat CB. As expected, type II cell activation within or near isolated GCs by P2Y2R agonists, ATP and UTP (100 μm), induced a rise in intracellular [Ca2+]. Moreover in perforated‐patch whole cell recordings from type II cells, these agonists caused a prolonged depolarization and a concentration‐dependent, delayed opening of non‐selective ion channels that was prevented by Panx‐1 blockers, carbenoxolone (5 μm) and 4,4′‐diisothiocyano‐2,2′‐stilbenedisulfonic acid (DIDS; 10 μm). Because Panx‐1 channels serve as conduits for ATP release, we hypothesized that paracrine, type II cell P2Y2R activation leads to ATP‐induced ATP release. In proof‐of‐principle experiments we used co‐cultured chemoafferent petrosal neurones (PNs), which express P2X2/3 purinoceptors, as sensitive biosensors of ATP released from type II cells. In several cases, UTP activation of type II cells within or near GCs led to depolarization or increased firing in nearby PNs, and the effect was reversibly abolished by the selective P2X2/3 receptor blocker, pyridoxalphosphate‐6‐azophenyl‐2′,4′‐disulphonic acid (PPADS; 10 μm). We propose that CB type II cells may function as ATP amplifiers during chemotransduction via paracrine activation of P2Y2Rs and Panx‐1 channels.
Heterogeneity and independency of unitary synaptic outputs from hippocampal CA3 pyramidal cells
Authors: Sasaki Takuya , Matsuki Norio , Ikegaya Yuji
Published: June 2012

Key points

Excitatory neurotransmission in the cortex is a local event that occurs at chemical synaptic junctions, but it has not been experimentally addressed at the large network scale.

Here we show that trial‐to‐trial variability in the synaptic transmission at hippocampal synapses is attributable to fluctuations in calcium elevations in axonal boutons, rather than to changes in the action potential waveform in axons.

Multiple patch‐clamp recordings from synaptically connected neural circuits revealed no correlation between synaptic outputs to two different postsynaptic cells from a common presynaptic cell.

This independency of synapses was likely to arise from unique calcium dynamics within presynaptic terminals.

Abstract  The variation of individual synaptic transmission impacts the dynamics of complex neural circuits. We performed whole‐cell recordings from monosynaptically connected hippocampal neurons in rat organotypic slice cultures using a synapse mapping method. The amplitude of unitary excitatory postsynaptic current (uEPSC) varied from trial to trial and was independent of the physical distance between cell pairs. To investigate the source of the transmission variability, we obtained patch‐clamp recordings from intact axons. Axonal action potentials (APs) were reliably transmitted throughout the axonal arbour and showed modest changes in width. In contrast, calcium imaging from presynaptic boutons revealed that the amplitude of AP‐evoked calcium transients exhibited large variations both among different boutons at a given trial and among trials in a given bouton. These results suggest that a factor contributing to the uEPSC fluctuations is the variability in calcium dynamics at presynaptic terminals. Finally, we acquired triple whole‐cell recordings from divergent circuit motifs with one presynaptic neuron projecting to two postsynaptic neurons. Consistent with the independency of calcium dynamics among axonal boutons, a series of uEPSC fluctuations was not correlated between the two postsynaptic cells, indicating that different synapses even from the same neuron act independently. We conclude that the intra‐bouton and inter‐bouton variability in AP‐induced calcium dynamics determine the heterogeneity and independency of uEPSCs.
Rotordynamic Performance of Shimmed Gas Foil Bearings for Oil-Free Turbochargers
Authors: Sim Kyuho , Yong-Bok Lee , Ho Kim Tae , Lee Jangwon
Published: June 2012

Oil-free turbochargers (TCs) will increase the power and efficiency of internal combustion engines, both sparking ignition and compression ignition, without engine oil lubricant feeding or scheduled maintenance. Using gas foil bearings (GFBs) in passenger vehicle TCs enables compact, lightweight, oil-free systems, along with accurate shaft motion. This paper presents extensive test measurements on GFBs for oil-free TCs, including static load-deflection measurements of test GFBs, rotordynamic performance measurements of a compressed air driven oil-free TC unit supported on test GFBs, and bench test measurements of the oil-free TC driven by a passenger vehicle diesel engine. Two configurations of GFBs, one original and the other modified with three shims, are subjected to a series of experimental tests. For the shimmed GFB, three metal shims are inserted under the bump-strip layers, in contact with the bearing housing. The installation of shims creates mechanical preloads that enhance a hydrodynamic wedge in the assembly radial clearance to generate more film pressure. Simple static load-deflection tests estimate the assembly radial clearance of the shimmed GFB, which is smaller than that of the original GFB. Model predictions agree well with test data. The discrepancy between the model predictions and test data is attributed to fabrication inaccuracy in the top foil and bump strip layers. Test GFBs are installed into a TC test rig driven by compressed air for rotordynamic performance measurements. The test TC rotor, 335 g in weight and 117 mm long, is coated with a commercially available, wear-resistant solid lubricant, Amorphous M, to prevent severe wear during start-up and shutdown in the absence of an air film. A pair of optical proximity probes positioned orthogonally at the compressor end record lateral rotor motions. Rotordynamic test results show that the shimmed GFB significantly diminishes the large amplitude of subsynchronous rotor motions arising in the unmodified GFB. Predicted synchronous rotor amplitudes and rigid body mode natural frequencies agree reasonably well with recorded test data. Finally, the oil-free TC is installed into a passenger vehicle diesel engine test bench. The TC rotor speed is controlled by the vehicle engine. Speed-up tests show dominant synchronous motion (1X) of the rotor. Whirl frequencies of the relatively small subsynchronous motions are associated with the rigid body natural mode of the TC rotor-GFB system as well as (forced) excitation from the four-cylinder diesel engine. The bench test measurements demonstrate a significant reduction in the amplitude of subsynchronous motions for the shimmed GFB, thus verifying the preliminary test results in the TC test rig driven by compressed air.
Convective Heat Transfer in Microchannels of Noncircular Cross Sections: An Analytical Approach
Authors: Shahsavari S. , Tamayol A. , Kjeang E. , Bahrami M.
Published: June 2012

Analytical solutions are presented for velocity and temperature distributions of laminar fully developed flow of Newtonian, constant property fluids in micro/minichannels of hyperelliptical and regular polygonal cross sections. The considered geometries cover several common shapes such as ellipse, rectangle, rectangle with round corners, rhombus, star-shape, and all regular polygons. The analysis is carried out under the conditions of constant axial wall heat flux with uniform peripheral heat flux at a given cross section. A linear least squares point matching technique is used to minimize the residual between the actual and the predicted values on the boundary of the channel. Hydrodynamic and thermal characteristics of the flow are derived; these include pressure drop and local and average Nusselt numbers. The proposed results are successfully verified with existing analytical and numerical solutions from the literature for a variety of cross sections. The present study provides analytical-based compact solutions for velocity and temperature fields that are essential for basic designs, parametric studies, and optimization analyses required for many thermofluidic applications.
Oscillation and Chaos in Combined Heat Transfer by Natural Convection, Conduction, and Surface Radiation in an Open Cavity
Authors: Wang Zhiyun , Yang Mo , Li Ling , Zhang Yuwen
Published: June 2012

Combined heat transfer by natural convection, conduction, and surface radiation in an open cavity is solved numerically by employing SIMPLE algorithm with QUICK scheme. The unsteady-state flow and heat transfer exhibited periodic oscillating or chaotic behaviors due to formation of the thermal plumes at the bottom wall. If the formation of thermal plumes is periodic, the oscillations of flow and heat transfer are also periodic. On the other hand, chaotic oscillations of flow and heat transfer can be observed when the formation of thermal plumes at the bottom surface is chaotic.
Tribological Properties of Steel and Steel Lubricated With a Poly-α-Olefin Containing Schiff Base Copper Complex
Authors: Gao Xinlei , Li Jian , Gao Wanzhen , Wu Li
Published: June 2012

Poly-α-olefin (PAO) is an important synthetic fluid in the field of industry lubricants. To improve the tribological properties of PAO, a Schiff base copper complex was added to the lubricants. The tribological properties of steel and steel lubricated with PAO and PAOs containing a Schiff base copper complex were studied. The friction and wear properties of steel and steel lubricated with PAO and PAOs containing a Schiff base copper complex were evaluated using a SST-ST pin-disc tester. The sliding friction was measured using lubricants with or without a Schiff base copper complex and analyzed using surface analysis techniques including scanning electron microscopy, Fourier transform infrared spectroscopy, and confocal white light microscopy. A UMT-2 universal tribometer was also used to study the tribological properties of modifying PAO containing the Schiff base copper complex. The Schiff base copper complex structure was found to assist in the formation of a stronger tribofilm; more than the tribofilm prepared by lubricating only with PAO and this is crucial in obtaining a low and stable coefficient of friction. A lower stable friction coefficient and wear was found for the steel/steel surface contact when using the PAOs containing the Schiff base copper complex compared to the samples lubricated with the PAO without additives. The excellent tribological performance of the PAOs containing the Schiff base copper complex is attributed to the formation of a useful tribofilm with organic and inorganic groups on the sliding surface.
Comparison of Two Linear Collectors in Solar Thermal Plants: Parabolic Trough Versus Fresnel
Authors: Giostri A. , Binotti M. , Silva P. , Macchi E. , Manzolini G.
Published: June 2012

Parabolic trough (PT) technology can be considered the state of the art for solar thermal power plants thanks to the almost 30 yr of experience gained in SEGS and, recently, Nevada Solar One plants in the United States and Andasol plant in Spain. One of the major issues that limits the wide diffusion of this technology is the high investment cost of the solar field and, particularly, of the solar collector. For this reason, research has focused on developing new solutions that aim to reduce costs. This paper compares, at nominal conditions, commercial Fresnel technology for direct steam generation with conventional parabolic trough technology based on synthetic oil as heat-transfer. The comparison addresses nominal conditions as well as annual average performance. In both technologies, no thermal storage system is considered. Performance is calculated by Thermoflex®, a commercial code, with a dedicated component to evaluate solar plant. Results will show that, at nominal conditions, Fresnel technology has an optical efficiency of 67%, which is lower than the 75% efficiency of the parabolic trough. Calculated net electric efficiency is about 19.25%, whereas PT technology achieves 23.6% efficiency. In off-design conditions, the performance gap between Fresnel and parabolic trough increases because the former is significantly affected by high incident angles of solar radiation. The calculated sun-to-electric annual average efficiency for a Fresnel plant is 10.2%, which is a consequence of the average optical efficiency of 38.8%; a parabolic trough achieves an overall efficiency of 16%, with an optical efficiency of 52.7%. An additional case with a Fresnel collector and synthetic-oil outlines the differences among the cases investigated. Since part of the performance difference between Fresnel and PT technologies is simply due to different definitions, we introduce additional indexes to make a consistent comparison. Finally, a simplified economic assessment shows that Fresnel collectors must reduce investment costs of at least 45% than parabolic trough to achieve the same levelized cost of electricity.
Sensitivity Analysis on Some Profitability Indices for Photovoltaic Grid–Connected Systems on Buildings: The Case of Two Top Photovoltaic European Areas
Authors: Talavera D. L. , Nofuentes G. , de la Casa J. , Aguilera J.
Published: June 2012

Frequently changing regulation codes, photovoltaic (PV) technology progress and variations in economic parameters that determine a specific economic scenario make a prospective owner of photovoltaic grid-connected systems (PVGCS) on buildings require information concerning the profitability of their investment on these systems. Hence, an analysis of the main economic factors of PVGCS on buildings addressed to ascertain their influence on the latter profitability is demanded and welcome. Consequently, a sensitivity analysis of some profitability indices such as the net internal rate of return, the net present value, and the discounted payback time has been carried out. This sensitivity analysis is aimed at demonstrating the influence on these indices of possible changes in the factors that are involved in their estimation. Two scenarios have been considered that closely resemble two top PV geographical areas: Germany and Spain. The results obtained here provide clear evidence that factors such as initial investment subsidy, dividends of own capital, taxes, annual loan interest exert a relatively small and similar influence on the net internal rate of return, the net present value, and the discounted payback time. However, other factors such as the initial investment, the annual PV electricity yield, and the PV electricity unitary price have a bigger influence on these profitability indices.
Solar Hydrogen Productivity of Ceria–Scandia Solid Solution Using Two-Step Water-Splitting Cycle
Authors: Lee Chong-il , Meng Qing-Long , Kaneko Hiroshi , Tamaura Yutaka
Published: June 2012

The reactivity of CeO2–Sc2O3 solid solution for solar hydrogen production via two-step water-splitting reaction has been studied in this work. The CeO2–Sc2O3 solid solution was synthesized by polymerized complex method (PCM) with various Sc content between 0 and 20 mol. %. Analysis results from online direct gas mass spectrometry (DGMS) suggest that Ce3 + formed by CeO2–Sc2O3 solid solution in the O2-releasing step could be completely oxidized by H2O to generate hydrogen and return to Ce4 + in the H2-generation step. A Ce0.97Sc0.03O1.985 generates the largest amount of O2 and H2 among present samples, and the reduction and oxidation ratios are about 9.9% (Ce) and 10% (Ce), respectively. An estimated H2-generation reaction rate is about 4 ml g−1min−1 for Ce0.97Sc0.03O1.985. This value is about seven times greater than that of Ce0.89Zr0.11O2. The high reaction rate of Ce0.97Sc0.03O1.985 makes all formed Ce3 + completely oxidized by H2O in 5 min in the H2-generation step. The reasons for high performance are discussed from the views of lattice distortion and the amount of oxygen vacancies formed in the lattice.
Influence of the Lagrangian Integral Time Scale Estimation in the Near Wall Region on Particle Deposition
Authors: Lecrivain Grégory , Hampel Uwe
Published: June 2012

In a high temperature pebble-bed reactor core where thousands of pebbles are amassed, the friction between the outer graphite layer of the fuel elements triggers the formation of carbonaceous dust. This dust is eventually conveyed by the cooling carrier phase and deposits in the primary circuit of the high temperature reactor. The numerical prediction of carbonaceous dust transport and deposition in turbulent flows is a key safety issue. Most particle tracking procedures make use of the Lagrangian integral time scale to reproduce the turbulent dispersion of the discrete phase. In the present Lagrangian particle tracking procedure, the effect of the Lagrangian integral time scale near the wall is thoroughly investigated. It is found that, in the linear sublayer, a value of the normalized wall normal component of the Lagrangian integral time scale lower that 4 delivers accurate particle deposition velocities. The value worked out here near the wall region is in accordance with Lagrangian integral time scales derived from recent direct numerical simulations.
Normal Contact Stiffness on Unit Area of a Mechanical Joint Surface Considering Perfectly Elastic Elliptical Asperities
Authors: Shi J. P. , Ma K. , Liu Z. Q.
Published: June 2012

Based on the Greenwood and Williamson theory, an assumption about the contact-area size of asperities on rough surfaces is proposed under the premise that the height of these asperities on rough surfaces is a Gaussian distribution. A formula has been derived to measure the number of asperities on 2D surfaces. The contact stiffness on a unit length of a 1D outline and that on a unit area of 2D surfaces are presented based on a formula for determining the number of asperities. The relationship between macro parameters, such as contact stiffness and micro parameters on the joint surface, is established.
Parametric Study of Dynamic Stall Flow Field With Synthetic Jet Actuation
Authors: Yen Joshua , Ahmed Noor A.
Published: June 2012

A parametric study of the interaction between dynamic stall and a zero-net mass flux synthetic jet installed on a wing was investigated by identifying the dominant frequencies in the resulting flow field using spectral analysis. The instantaneous pressure distribution around an NACA 0020 wing was recorded by performing static and dynamic experiments using an open jet subsonic wind tunnel located at the aerodynamics laboratory of the University of New South Wales. The results obtained provided valuable insight into the interaction process. The oscillation frequency and its harmonics were identified in baseline dynamic experiments, as well as the jet frequency and offset frequencies with synthetic jet actuation. The offset frequencies, similar to beat frequencies, were found to be a dynamic effect and represented the complex and nonlinear interaction between dynamic stall and the synthetic jet. The study suggests that low amplitude synthetic jet actuation would be an effective method in enhancing the overall aerodynamic efficiency of the wing. This confirmed the viability of utilizing synthetic jets in dynamic stall control.
Using computerised decision support to improve compliance of cancer multidisciplinary meetings with evidence-based guidance
Authors: Patkar Vivek , Acosta Dionisio , Davidson Tim , Jones Alison , Fox John , Keshtgar Mohammed
Published: June 2012

Objectives

The cancer multidisciplinary team (MDT) meeting (MDM) is regarded as the best platform to reduce unwarranted variation in cancer care through evidence-compliant management. However, MDMs are often overburdened with many different agendas and hence struggle to achieve their full potential. The authors developed an interactive clinical decision support system called MATE (Multidisciplinary meeting Assistant and Treatment sElector) to facilitate explicit evidence-based decision making in the breast MDMs.

Design

Audit study and a questionnaire survey.

Setting

Breast multidisciplinary unit in a large secondary care teaching hospital.

Participants

All members of the breast MDT at the Royal Free Hospital, London, were consulted during the process of MATE development and implementation. The emphasis was on acknowledging the clinical needs and practical constraints of the MDT and fitting the system around the team's workflow rather than the other way around. Delegates, who attended MATE workshop at the England Cancer Networks' Development Programme conference in March 2010, participated in the questionnaire survey.

Outcome measures

The measures included evidence-compliant care, measured by adherence to clinical practice guidelines, and promoting research, measured by the patient identification rate for ongoing clinical trials.

Results

MATE identified 61% more patients who were potentially eligible for recruitment into clinical trials than the MDT, and MATE recommendations demonstrated better concordance with clinical practice guideline than MDT recommendations (97% of MATE vs 93.2% of MDT; N=984). MATE is in routine use in breast MDMs at the Royal Free Hospital, London, and wider evaluations are being considered.

Conclusions

Sophisticated decision support systems can enhance the conduct of MDMs in a way that is acceptable to and valued by the clinical team. Further rigorous evaluations are required to examine cost-effectiveness and measure the impact on patient outcomes. The decision support technology used in MATE is generic and if found useful can be applied across medicine.
Micrographia and related deficits in Parkinson's disease: a cross-sectional study
Authors: Wagle Shukla Aparna , Ounpraseuth Songthip , Okun Michael S , Gray Vickie , Schwankhaus John , Metzer Walter Steven
Published: June 2012

Objectives

To determine the prevalence and clinical features associated with micrographia in Parkinson's Disease (PD).

Setting

This study was conducted at a Movement Disorders clinic located in a Veteran Administration Hospital.

Participants

PD subjects were included only if they satisfied UK Parkinson's Disease Society criteria for diagnosis. Subjects with history of severe tremors, dystonia, dyskinesia, strokes, peripheral neuropathy and dementia were excluded.

Design

This was a case–control study where PD subjects were prospectively enrolled and their demographics, Hoehn & Yahr stage, Unified Parkinson's Disease Rating Scale and Mini Mental Status examination (MMSE) scores were recorded. All subjects were specifically asked for micrographia on history and the handwritings were quantitatively documented. Bradykinesia was determined by history and quantified by a finger tap, Purdue pegboard and a timed walk test. Similarly, hypophonia was determined by history and the volume of speech quantified using a decibel meter. Controls were enrolled for validation of handwriting test scores and decibel meter recordings.

Primary outcome measures

Prevalence of micrographia in the PD cohort and the clinical factors that correlate with micrographia.

Results

68 subjects with PD were enrolled (68 men; mean age 72.3 years). Micrographia was identified in 63.2% of the cohort on verbal history and in 50% of the cohort when the handwriting test was used for ascertainment. Micrographia ascertained on history correlated significantly with disease severity (Hoehn & Yahr stage), motor impairment (Unified Parkinson's Disease Rating Scale), cognitive impairment (MMSE) and both bradykinesia and hypophonia determined by history and quantitative testing. Micrographia on handwriting test correlated with age (p=0.02), MMSE testing (p=0.04), hypophonia by history (p=0.01) and bradykinesia by quantitative testing (p=0.04).

Conclusion

Micrographia was found in nearly half of the PD cohort. Disease severity and impaired cognition were important clinical correlates. Micrographia had a significant relationship with bradykinesia and hypophonia, suggesting a possible overlap in their pathophysiology.