bluuebunny/crossref_metadata_2025 huggingface dataset:
Orthodontic correction of overjet/overbite (‘parrot mouth’) in 73 foals (1999–2013)
Authors: Easley J. , Dixon P. M. , Reardon R. J. M.
Published: November 2015

Reasons for performing study

There are limited reports on the efficacy of functional orthodontic correction of overjet or overbite in foals.

Objectives

To report the outcome of using orthodontic tension bands in combination with an inclined plane biteplate in the treatment of overjet, with or without concurrent overbite, rates of correction of these 2 malocclusions and associated complications. And to examine factors associated with outcomes.

Study design

Retrospective case series.

Methods

Clinical records for 73 foals treated at a single clinic, by the same surgeon were analysed. Overall change and rates of change in overjet and overbite were calculated. Associations between potential explanatory variables including age, severity of initial malocclusion and surgeon experience were examined using linear regression.

Results

Records for 73 foals (43 colts, 30 fillies) were evaluated. The median number of implant placements per animal was 2 (range 1–4). Of 61 cases with complete records, reduction in overjet and overbite dimensions were achieved in 95% and 90% of foals, respectively, with mean reductions in malocclusions of 9.9 and 8.4 mm, respectively. Complete reduction in overjet was achieved in 25% (15/61) and reduction of malocclusion dimensions to ≤5 mm (i.e. functionally corrected) was achieved in 51% (31/61). Increasing animal age was significantly associated with decreased total reduction in overjet and decreased rate of reduction in overbite. Increased original severity of overbite was significantly associated with increased rate of its correction. Short‐term complications included intraoperative haemorrhage, transient facial nerve neuropraxia and irritation of the mare's udder by the brace. Longer‐term complications included cheek teeth diastema formation and incisor discoloration and maleruption.

Conclusions

Using this technique, correction or improvement of these malocclusions is rapid, with minimal complications. Often more than one implant is required. Animal age at the start of treatment is associated with rate and amount of correction achievable, so initiating treatment at an early age is recommended.
Work ties beget community? Assessing interactions among transnational private governance organizations in sustainable agriculture
Authors: FRANSEN LUC , SCHALK JELMER , AULD GRAEME
Published: November 2015

Transnational private governance organizations (TPGOs) set standards for various sustainability issues and industries. TPGOs individually address only facets of larger problems such as land conversion, and competition among TPGOs also affects TPGO governance, meaning coordination across their activities can be required. Studies have shown that ties between TPGOs and other organizations facilitate information sharing, coordination and socialization. A systematic analysis of the structure of such ties, however, is lacking. Using the employment ties of staff and governors, we analyse the inter‐organizational communities of TPGOs that focus on agriculture. Our findings cast doubt on the existence of a coherent community of sustainable agricultural TPGOs: very few communities involve multiple TPGOs. While TPGOs with a similar product focus may form links with similar organizations, there are few direct and indirect ties among TPGOs. Researchers should therefore be cautious about assuming that a TPGO policy community crossing organizational and policy divides currently exists.
Ten years on: what can Google Earth offer the geoscience community?
Authors: Mather A.E. , Mills S. , Stokes M. , Fyfe R.
Published: November 2015

Google Earth has been part of most geoscientists' computer (and mobile) desktops for a decade, and this year Google Earth Professional has become freely available to all with a universal license key. Many users are still, however, not aware of the full potential that it can offer across a range of teaching and research areas in the geosciences. Here a pragmatic look is taken at some of the current key uses in terms of resources and applications and how they can help in research and training educational roles in the geosciences.
miRNA‐548p suppresses hepatitis B virus X protein associated hepatocellular carcinoma by downregulating oncoprotein hepatitis B x‐interacting protein
Authors: Hu Xiu‐Mei , Yan Xiao‐Hui , Hu Yan‐Wei , Huang Jin‐Lan , Cao Shun‐Wang , Ren Ting‐Yu , Tang Yue‐Ting , Lin Li , Zheng Lei , Wang Qian
Published: November 2015

Aim

miR‐548p is a recently identified and poorly characterized miRNA. However, its role of miR‐548p in tumorigenesis and progression remains poorly understood. Here, we aimed to investigate the biofunction of miR‐548p in hepatocellular carcinogenesis.

Methods

The expression levels of miR‐548p were detected by quantitative reverse transcription polymerase chain reaction (qRT–PCR). The role of miR‐548p in hepatocellular carcinoma (HCC) was determined by colony formation, flow cytometry assay and nude mice xenograft experiments. miR‐548p target genes were analyzed by miRNA target predication programs and verified by qRT–PCR, western blotting assay and dual‐luciferase reporter assay.

Results

miR‐548p is repressed by hepatitis B virus X protein (HBx) in HCC tumor tissues and hepatoma cells, and inhibited cell growth by inhibiting cell proliferation and promoting cell apoptosis. miR‐548p directly downregulated the expression of hepatitis B x‐interacting protein (HBXIP) by binding to the 3′‐untranslated region of HBXIP mRNA. Further study showed that hepatocyte nuclear factor‐4a (HNF4A) promoted the expression of miR‐548p and inhibited the transcription of HBXIP. HNF4A is a dominant transcriptional regulator of hepatocyte differentiation and hepatocellular carcinogenesis, and is shown to be repressed by HBx.

Conclusion

We proposed the model for HBx/HNF4A/miR‐548p/HBXIP pathway that controls hepatoma cell growth and tumorigenesis of HCC. miR‐548p was identified as a tumor‐suppressor in HBx‐associated hepatocellular carcinogenesis.
Optimal biological parameters for rearing Ooencyrtus pityocampae on the new laboratory host Philosamia ricini
Authors: Tunca H. , Colombel E.‐A. , Ben Soussan T. , Buradino M. , Galio F. , Tabone E.
Published: November 2015

Biological control programmes involving Ooencyrtus pityocampae Mercet (Hymenoptera: Encyrtidae) have proved effective at reducing the damage caused by the pine processionary Thaumetopoea pityocampa Denis & Schiffermüller (Lepidoptera: Thaumatopoeidae). In this study, the biological variables that influence the parasitism of O. pityocampae on the new laboratory host Philosamia ricini Danovan (Lepidoptera: Saturniidae) have been investigated. Laboratory experiments were conducted under the conditions of 25 ± 1°C, 65 ± 5% R.H (relative humidity) and a photoperiod of 16 : 8 h (L : D = light : dark). The host egg age and parasitoid age are often regarded as being key factors influencing the emergence rate of O. pityocampae. The optimal age of host eggs for parasitization was 1–2 days, and the emergence rate was highest with 5‐day‐old female parasitoids. Thus, our results define the optimal conditions for the effective and economic rearing of parasitoids as follows: one 5‐day‐old female parasitoid per 50 (1–2)‐day‐old host eggs. The development time of O. pityocampae ranged between 19.5 and 22.6 days. Parasitoids that were exposed to bio‐honey survived 10.5 times longer than those that did not receive supplemental food. O. pityocampae was reared for more than nine generations on the eggs of P. ricini. Consequently, P. ricini has been found as a suitable new laboratory host for the mass rearing of O. pityocampae for the use of biological control programmes against T. pityocampa in future.
Association Between Necropsy Evidence of Disseminated Intravascular Coagulation and Hemostatic Variables Before Death in Horses With Colic
Authors: Cesarini C. , Cotovio M. , Ríos J. , Armengou L. , Jose‐Cunilleras E.
Published: November 2015

Background

Disseminated intravascular coagulation (DIC) is frequent in horses with severe gastrointestinal disorders. Postmortem studies have found fibrin microthrombi in tissues of these horses, but studies relating these histopathological findings with antemortem hemostatic data are lacking.

Hypothesis

Antemortem classification of coagulopathy is related to the presence and severity of fibrin deposits observed postmortem in horses with severe gastrointestinal disorders.

Animals

Antemortem hemostatic profile data and postmortem tissue samples (kidney, lung, liver) from 48 horses with colic.

Methods

Tissue samples were stained with phosphotungstic acid hematoxylin and immunohistochemical methods for histological examination. A fibrin score (grades 0–4) was assigned for each technique, tissue and horse, as well as the presence or absence ofDICat postmortem examination. D‐dimer concentration, prothrombin time (PT), activated partial thromboplastin time (aPTT), and antithrombin (AT) activity, as well as the clinicopathological evidence of coagulopathy, were determined from plasma samples collected 0–24 hours before death or euthanasia. Histologic and clinicopathologic data from the same horses were compared retrospectively.

Results

No association was found between antemortem classification of coagulopathy and postmortem diagnosis ofDICbased on tissue fibrin deposition. None of the hemostatic parameters was significantly different between horses with or without postmortem diagnosis ofDIC. There was no association between horses with fibrin in tissues or different cut‐offs for D‐dimer concentration and postmortem evidence ofDIC.

Conclusions and Clinical Importance

Abnormalities of the routine clotting profile, including D‐dimer concentration, were not useful in predicting histologic evidence ofDICat necropsy in horses with severe gastrointestinal disorders.
A model of acute kidney injury in mice with cirrhosis and infection
Authors: Carl Daniel E. , Ghosh Siddhartha S. , Gehr Todd W.B. , Abbate Antonio , Toldo Stefano , Sanyal Arun J.
Published: November 2015

Background & Aims

Infectious acute kidney injury (AKI) is a life threatening complication of cirrhosis with limited therapeutic options. The aim of this study was to develop a model of infectious AKI in cirrhotic mice.

Methods

Cirrhosis was established by intragastric administration of carbon tetrachloride (CCl4). Systemic haemodynamics was assessed invasively while cardiac function was assessed by echocardiography. AKI was induced using varying doses of lipopolysaccharide (LPS) titrated to produce 50% lethality. Renal function was assessed from serum creatinine and urine output (UOP). Renal injury was evaluated by urinalysis (proteinuria and casts) and renal histology. These mice were compared to: (i) normal mice, (ii) normal mice + LPS, and (iii) mice treated with CCl4 alone.

Results

Cirrhosis with increased cardiac output, decreased systemic vascular resistance, activation of renin–angiotensin–aldosterone axis developed after 12 weeks of CCl4 administration. LPS injection produced a dose‐dependent increase in mortality (33% at 2 mg/kg vs. 80% at 6 mg/kg) without urine (casts or proteinuria) or histological evidence of tubular injury. 2 mg/kg LPS injection produced a rise in creatinine (0.79 ± 0.27 mg/dl in CCl4+LPS compared to 0.45 ± 0.14 in CCl4 alone, P < 0.05) and a decrease in UOP (0.86 ± 0.4 ml/16 h in CCl4 + LPS compared to 1.70 ± 0.7 ml/16 h in CCl4 mice, P < 0.05). UOP remained low in mice that died while it recovered over 48–72 h in those that recovered. Control mice treated with 2 mg/kg LPS did not experience AKI.

Conclusions

Cirrhotic CCl4 treated mice develop functional AKI and mimic most of the features of infectious AKI following LPS injection.
Sofosbuvir and simeprevir in hepatitis C genotype 1‐patients with end‐stage renal disease on haemodialysis or GFR <30 ml/min
Authors: Nazario Hector E. , Ndungu Milka , Modi Apurva A.
Published: November 2015

Background & Aims

Treating chronic hepatitis C (CHC) in patients with end‐stage renal disease (ESRD) has suboptimal tolerability and cure rates. Safety and efficacy of sofosbuvir plus simeprevir regimen in CHC‐infected patients with ESRD on haemodialysis (HD) or glomerular filtration rate (GFR) <30 ml/min is unknown. We evaluated the safety and efficacy of sofosbuvir and simeprevir in this special patient population.

Methods

All (n = 17) patients in the analysis had ESRD on HD or GFR <30 ml/min. All received sofosbuvir 400 mg daily and simeprevir 150 mg daily, without ribavirin for 12 weeks. Safety and efficacy data were collected; including SVR4 and SVR12 data for all patients after completing therapy.

Results

In this 17 patient cohort, eight (47%) were cirrhotic, four (24%) had stage three liver fibrosis and 13 (76%) were genotype 1A. All 17 have completed 12 weeks of therapy. Treatment was overall well tolerated with no treatment discontinuations reported. Four (24%) patients reported mild adverse events (AE). These AEs were insomnia (n = 2), headache (n = 1), nausea (n = 1) and worsening anaemia requiring blood transfusion (n = 1). All 17 patients reached post‐treatment week‐12 follow‐up, and achieved SVR12 or virological cure (100% SVR12).

Conclusions

Daily, full dose of sofosbuvir plus simeprevir for 12 weeks of therapy appears to be well tolerated in patients with ESRD on HD or GFR <30 ml/min. Most common AEs resembled those of healthier CHC patients without significant renal impairment. The cure rates obtained in this cohort treated with sofosbuvir and simeprevir are dramatically superior to any previous treatment regimen studied & published in this special patient population.
Behavior‐Based Price Discrimination with Experience Goods
Authors: Chung Hoe Sang
Published: November 2015

This paper examines the profitability of behavior‐based price discrimination (BBPD) by duopolists producing horizontally differentiated experience goods. Considering a three‐stage game in which the firms first make price discrimination decisions followed by two‐stage pricing decisions, the two main results we obtain are the following: (i) if consumers underestimate the quality of the products at a level that is not very low, there are two subgame perfect Nash equilibria where both firms do not collect information about consumers' purchase histories so that neither firm price discriminates and where both firms collect consumer information to practice BBPD; (ii) BBPD is more profitable than uniform pricing if consumers overestimate at a more than moderate level.
Hybridization promotes speciation in Coenonympha butterflies
Authors: Capblancq Thibaut , Després Laurence , Rioux Delphine , Mavárez Jesús
Published: November 2015

Hybridization has become a central element in theories of animal evolution during the last decade. New methods in population genomics and statistical model testing now allow the disentangling of the complexity that hybridization brings into key evolutionary processes such as local adaptation, colonization of new environments, species diversification and extinction. We evaluated the consequences of hybridization in a complex of three alpine butterflies in the genus Coenonympha, by combining morphological, genetic and ecological analyses. A series of approximate Bayesian computation procedures based on a large SNP data set strongly suggest that the Darwin's Heath (Coenonympha darwiniana) originated through hybridization between the Pearly Heath (Coenonympha arcania) and the Alpine Heath (Coenonympha gardetta) with different parental contributions. As a result of hybridization, the Darwin's Heath presents an intermediate morphology between the parental species, while its climatic niche seems more similar to the Alpine Heath. Our results also reveal a substantial genetic and morphologic differentiation between the two geographically disjoint Darwin's Heath lineages leading us to propose the splitting of this taxon into two different species.
The concerted impact of domestication and transposon insertions on methylation patterns between dogs and grey wolves
Authors: Janowitz Koch Ilana , Clark Michelle M. , Thompson Michael J. , Deere‐Machemer Kerry A. , Wang Jun , Duarte Lionel , Gnanadesikan Gitanjali E. , McCoy Eskender L. , Rubbi Liudmilla , Stahler Daniel R. , Pellegrini Matteo , Ostrander Elaine A. , Wayne Robert K. , Sinsheimer Janet S. , vonHoldt Bridgett M.
Published: November 2015

The process of domestication can exert intense trait‐targeted selection on genes and regulatory regions. Specifically, rapid shifts in the structure and sequence of genomic regulatory elements could provide an explanation for the extensive, and sometimes extreme, variation in phenotypic traits observed in domesticated species. Here, we explored methylation differences from >24 000 cytosines distributed across the genomes of the domesticated dog (Canis familiaris) and the grey wolf (Canis lupus). PCA and model‐based cluster analyses identified two primary groups, domestic vs. wild canids. A scan for significantly differentially methylated sites (DMSs) revealed species‐specific patterns at 68 sites after correcting for cell heterogeneity, with weak yet significant hypermethylation typical of purebred dogs when compared to wolves (59% and 58%, P < 0.05, respectively). Additionally, methylation patterns at eight genes significantly deviated from neutrality, with similar trends of hypermethylation in purebred dogs. The majority (>66%) of differentially methylated regions contained or were associated with repetitive elements, indicative of a genotype‐mediated trend. However, DMSs were also often linked to functionally relevant genes (e.g. neurotransmitters). Finally, we utilized known genealogical relationships among Yellowstone wolves to survey transmission stability of methylation marks, from which we found a substantial fraction that demonstrated high heritability (both H2 and h2 > 0.99). These analyses provide a unique epigenetic insight into the molecular consequences of recent selection and radiation of our most ancient domesticated companion, the dog. These findings suggest selection has acted on methylation patterns, providing a new genomic perspective on phenotypic diversification in domesticated species.
Isolation and characterization of dental epithelial cells derived from amelogenesis imperfecta rat
Authors: Adiningrat A , Tanimura A , Miyoshi K , Hagita H , Yanuaryska RD , Arinawati DY , Horiguchi T , Noma T
Published: November 2015

Objective

Disruption of the third zinc finger domain of specificity protein 6 (SP6) presents an enamel‐specific defect in a rat model of amelogenesis imperfecta (AMI rats). To understand the molecular basis of amelogenesis imperfecta caused by the Sp6 mutation, we established and characterized AMI‐derived rat dental epithelial (ARE) cells.

Materials and Methods

ARE cell clones were isolated from the mandibular incisors of AMI rats, and amelogenesis‐related gene expression was analyzed by reverse transcription polymerase chain reaction (RT‐PCR). Localization of wild‐type SP6 (SP6WT) and mutant‐type SP6 (SP6AMI) was analyzed by immunocytochemistry. SP6 transcriptional activity was monitored by rho‐associated protein kinase 1 (Rock1) promoter activity with its specific binding to the promoter region in dental (G5 and ARE) and non‐dental (COS‐7) epithelial cells.

Results

Isolated ARE cells were varied in morphology and gene expression. Both SP6WT and SP6AMI were mainly detected in nuclei. The promoter analysis revealed that SP6WT and SP6AMI enhanced Rock1 promoter activity in G5 cells but that enhancement by SP6AMI was weaker, whereas no enhancement was observed in the ARE and COS‐7 cells, even though SP6WT and SP6AMI bound to the promoter in all instances.

Conclusion

ARE cell clones can provide a useful in vitro model to study the mechanism of SP6‐mediated amelogenesis imperfecta.
Reasons as Premises of Good Reasoning
Authors: Way Jonathan
Published: November 2015

Many philosophers have been attracted to the view that reasons are premises of good reasoning – that reasons to φ are premises of good reasoning towards φ‐ing. However, while thisreasoning viewis indeed attractive, it faces a problem accommodating outweighed reasons. In this article, I argue that the standard solution to this problem is unsuccessful and propose an alternative, which draws on the idea that good patterns of reasoning can be defeasible. I conclude by drawing out implications for the debate over pragmatic reasons for belief and other attitudes and for one influential form of reductionism about the normative.
High levels of physical activity are associated with poorer asthma control in young females but not in males
Authors: Lövström Ludvig , Emtner Margareta , Alving Kjell , Nordvall Lennart , Borres Magnus P. , Janson Christer , Malinovschi Andrei
Published: November 2015

Background and objective

Earlier studies on the levels of physical activity in asthma patients compared with controls have yielded varying results. We have previously reported that high versus moderate levels of physical activity were associated with higher prevalence of wheezing, especially in females. Here we studied the levels of physical activity in young patients with asthma and healthy subjects and their effect on asthma control.

Methods

Four hundred eight physician‐diagnosed patients with asthma and 118 controls (10–34 years) answered questions concerning frequency and/or duration of physical activity and undertook the Asthma Control Test (ACT), spirometry, methacholine challenges and exhaled nitric oxide measurements.

Results

Asthma patients were more frequently physically active (P = 0.01) and for longer durations (P = 0.002) than controls. Highly versus moderately physically active patients with asthma had a higher prevalence of not well‐controlled asthma (ACT < 20) when physical activity was assessed by frequency (40.6% vs 24.1%, P = 0.001) or duration (39.0% vs 21.7%, P < 0.001). This was only seen in females who had reduced ACT items (P < 0.05). Frequently versus moderately active females had an odds ratio of 4.81 (2.43, 9.51) to have ACT < 20, while no such effect was found in males (OR 1.18 (0.61, 2.30)) and this interaction was statistically significantly associated with gender (P = 0.003). No differences in fraction of exhaled nitric oxide or methacholine reactivity were found between moderately and highly physically active females with asthma.

Conclusion

Young asthma patients were more active than controls. High levels of physical activity were associated with poor asthma control as judged by the ACT in females, but not in males, and this appears unrelated to airway inflammation or responsiveness.
A re‐analysis of the 1968 Saltin et al. “Bedrest” paper
Authors: Wagner P. D.
Published: November 2015

In 1968, Saltin et al. published a landmark paper describing the alterations in VO2max resulting from two sequential interventions – 20 days of bed rest and almost 8 weeks of training. They concluded that bed rest reduced VO2max through reductions in maximal cardiac output, while training enhanced VO2max by an equal combination of increased maximal cardiac output and increased arterio‐venous [O2] difference (A‐V Δ [O2]). At the time, A‐V Δ [O2] was taken as an index of peripheral (skeletal muscle) adaptation. A key interpretive element that was not featured was consideration of how alterations in cardiac output affect the O2 extraction process secondary to changes in red cell transit time through the muscle microcirculation, even in the absence of adaptive changes in the skeletal muscles per se. For the 2015 Saltin Symposium, it was therefore thought appropriate to re‐examine the 1968 O2 transport data and re‐evaluate the roles central cardiovascular and peripheral muscle changes after bed rest and training allowing for their interaction. The analysis supports the conclusion that bed rest reduced VO2max mainly through reduction in cardiac output, but after training, it is proposed that the 1968 conclusions should be modified: the majority of the increase in VO2max from the control state can be attributed to an improvement in diffusive unloading of O2 from the muscle microcirculation, with a much smaller role for enhanced blood flow.
Central and peripheral hemodynamics in exercising humans: leg vs arm exercise
Authors: Calbet J. A. L. , González‐Alonso J. , Helge J. W. , Søndergaard H. , Munch‐Andersen T. , Saltin B. , Boushel R.
Published: November 2015

In humans, arm exercise is known to elicit larger increases in arterial blood pressure (BP) than leg exercise. However, the precise regulation of regional vascular conductances (VC) for the distribution of cardiac output with exercise intensity remains unknown. Hemodynamic responses were assessed during incremental upright arm cranking (AC) and leg pedalling (LP) to exhaustion (Wmax) in nine males. Systemic VC, peak cardiac output (Qpeak) (indocyanine green) and stroke volume (SV) were 18%, 23%, and 20% lower during AC than LP. The mean BP, the rate‐pressure product and the associated myocardial oxygen demand were 22%, 12%, and 14% higher, respectively, during maximal AC than LP. Trunk VC was reduced to similar values at Wmax. At Wmax, muscle mass‐normalized VC and fractional O2 extraction were lower in the arm than the leg muscles. However, this was compensated for during AC by raising perfusion pressure to increase O2 delivery, allowing a similar peak VO2 per kg of muscle mass in both extremities. In summary, despite a lower Qpeak during arm cranking the cardiovascular strain is much higher than during leg pedalling. The adjustments of regional conductances during incremental exercise to exhaustion depend mostly on the relative intensity of exercise and are limb‐specific.
Mitochondrial specialization revealed by single muscle fiber proteomics: focus on the Krebs cycle
Authors: Schiaffino S. , Reggiani C. , Kostrominova T. Y. , Mann M. , Murgia M.
Published: November 2015

We have developed a highly sensitive mass spectrometry‐based proteomic workflow to examine the proteome of single muscle fibers. This study revealed significant differences in the mitochondrial proteome of the four major fiber types present in mouse skeletal muscle. Here, we focus on Krebs cycle enzymes and in particular on the differential distribution of the two mitochondrial isocitrate dehydrogenases, IDH2 and IDH3. Type 1/slow fibers contain high levels of IDH2 and relatively low levels of IDH3, whereas fast 2X and 2B fibers show an opposite expression pattern. The findings suggest that in skeletal muscle, IDH2 functions in the forward direction of the Krebs cycle and that substrate flux along the cycle occurs predominantly via IDH2 in type 1 fibers and via IDH3 in 2X and 2B fibers. IDH2‐mediated conversion of isocitrate to α‐ketoglutarate leads to the generation of NADPH, which is critical to buffering the H2O2 produced by the respiratory chain. Nicotinamide nucleotide transhydrogenase (NNT), the other major mito‐chondrial enzyme involved in NADPH generation, is also more abundant in type 1 fibers. We suggest that the continuously active type 1 fibers are endowed with a more efficient H2O2 scavenging capacity to cope with the higher levels of reactive oxygen species production.
Mitochondrial coupling and capacity of oxidative phosphorylation in skeletal muscle of Inuit and Caucasians in the arctic winter
Authors: Gnaiger E. , Boushel R. , Søndergaard H. , Munch‐Andersen T. , Damsgaard R. , Hagen C. , Díez‐Sánchez C. , Ara I. , Wright‐Paradis C. , Schrauwen P. , Hesselink M. , Calbet J. A. L. , Christiansen M. , Helge J. W. , Saltin B.
Published: November 2015

During evolution, mitochondrial DNA haplogroups of arctic populations may have been selected for lower coupling of mitochondrial respiration to ATP production in favor of higher heat production. We show that mitochondrial coupling in skeletal muscle of traditional and westernized Inuit habituating northern Greenland is identical to Danes of western Europe haplogroups. Biochemical coupling efficiency was preserved across variations in diet, muscle fiber type, and uncoupling protein‐3 content. Mitochondrial phenotype displayed plasticity in relation to lifestyle and environment. Untrained Inuit and Danes had identical capacities to oxidize fat substrate in arm muscle, which increased in Danes during the 42 days of acclimation to exercise, approaching the higher level of the Inuit hunters. A common pattern emerges of mitochondrial acclimatization and evolutionary adaptation in humans at high latitude and high altitude where economy of locomotion may be optimized by preservation of biochemical coupling efficiency at modest mitochondrial density, when submaximum performance is uncoupled from VO2max and maximum capacities of oxidative phosphorylation.
Modular Flow Structure Design for a Single-Phase Manifold Microchannel Cold Plate
Authors: Zhou Feng , Liu Yan , Joshi Shailesh N. , Liu Yanghe , Dede Ercan M.
Published: November 2015

The present work is generally related to the design of a manifold microchannel heat sink with high modularity and performance for electronics cooling, utilizing two well established (i.e., jet impingement and channel flow) cooling technologies. The present cold plate design provides flexibility to assemble manifold sections in five different configurations to reach different flow structures, and thus different cooling performance, without redesign. The details of the modular manifold and possible configurations of a cold plate comprising three manifold sections are shown herein. A conjugate flow and heat transfer 3-D model is developed for each configuration of the cold plate to demonstrate the merits of each modular design. Parallel flow configurations are used to satisfy a uniform cooling requirement from each module, but a “U-shape” parallel flow “base” configuration cools the modules more uniformly than a “Z-shape” flow pattern due to intrinsic pressure distribution characteristics. A serial fluid flow configuration requires the minimum coolant flow rate with a gradually increasing device temperature along the flow direction. Two mixed (i.e., parallel + serial flow) configurations achieve either cooling performance similar to the “U-shape” configuration with slightly more than half of the coolant flow rate, or cooling of a specific module to a much lower temperature level. Generally speaking, the current cold plate design significantly extends its application to different situations with different cooling requirements.
Numerical and Experimental Investigation of Shell-and-Tube Phase Change Material Thermal Storage Unit
Authors: Sherer Thomas H. , Joshi Yogendra
Published: November 2015

A shell-and-tube phase change material (PCM) thermal energy storage (TES) unit has been analyzed numerically and experimentally. The tube bank is filled with commercial paraffin RUBITHERM RT 28 HC PCM, which melts as the heat transfer fluid (HTF) flows across the tubes. A fully-implicit one-dimensional control volume formulation that utilizes the enthalpy method for phase change has been developed to determine the transient temperature distributions in both the PCM and the tubes themselves. The energy gained by a column of tubes is used to determine the exit bulk HTF temperature from that column, ultimately leading to an exit HTF temperature from the TES unit. This paper presents a comparison of the numerical and experimental results for the transient temperature profiles of the PCM-filled tubes and HTF.
Comparative Analysis of Different In Row Cooler Management Configurations in a Hybrid Cooling Data Center
Authors: Gao Tianyi , Sammakia Bahgat G. , Geer James , Murray Bruce , Tipton Russell , Schmidt Roger
Published: November 2015

The heat dissipated by electronic equipment inside data centers is increasing at a rapid rate due to the increasing of performance requirement and package density. This ever increasing power leads to critical challenges of thermal management for these high power density data centers. Energy consumption is also a key issue for high density data centers. Roughly 1.5% of all U.S. electricity consumption in the year 2006 was related to data centers, while that number increased to 2% by the year 2010. In 2013, U.S. data centers consumed approximately 91 billion kilowatt-hours of electricity. This amount of the electricity equals the annual output of 34 500-megawatt coal-fired power plants [1]. Cooling systems constitute a significant portion of the energy consumption of data centers, being approximately 25%∼35% of the total energy usage. Therefore, there is a large potential to save energy by optimizing current existing cooling systems and investigating new cooling technologies, and, at the same time, improving the overall cooling capacity and efficiency. This paper describes and investigates a hybrid cooling technology which utilizes in row coolers in existing raised floor air cooled data centers. The in row cooler functions as a liquid-to-air heat exchanger. In addition to the traditional raised floor cold aisle-hot aisle arrangements, the in row cooler is installed between the IT equipment to enable delivering the liquid coolant medium closer to the IT equipment. The in row coolers intake the hot air from the hot aisle, condition it, and supply the chilled air to the cold aisle. Thus, by extracting a large portion of the heat more directly into the cooling liquid through the in row coolers compared with the perimeter CRAH unit, the overall cooling performance and efficiency can potentially be improved. CFD models for an in row cooler and a representative data center room are developed. Experimentally characterized performance data are used to calibrate and validate the models. The models are then used to conduct a detailed computational analysis to assess the effectiveness of different arrangement configurations of in row cooler units in two rows of racks along one cold aisle. The detailed performance of the entire cold aisle is characterized using the rack inlet air temperature and a temperature nonuniformity factor. The impact of CRAH location and room layout are also investigated. This study is based on a practical problem and the corresponding results and analysis provide basic installation and design guidelines for future equipment upgrading in certain parts of the data center.
Durability of Low Melt Alloys as Thermal Interface Materials
Authors: Roy Chandan K. , Harris Daniel K. , Bhavnani Sushil , Hamilton Michael C. , Johnson Wayne , Knight Roy W.
Published: November 2015

This paper focuses on developing a reliable thermal interface material (TIM) using low melt alloys (LMAs) containing gallium (Ga), indium (In), bismuth (Bi), and tin (Sn). The investigation described herein involved the in situ thermal performance of the LMAs as well as performance evaluation after accelerated life cycle testing, which included isothermal aging at 130°C and thermal cycling from −40°C to 80°C. Three alloys (75.5Ga &24.5In, 100Ga, and 51In, 32.5Bi &16.5Sn) were chosen for testing the thermal performance. Testing methodologies used follow ASTM D5470 protocols and the results are compared with some commercially available TIMs. The LMAs-substrate interaction was investigated by applying the alloys using different surface treatments (copper and tungsten). Measurements show that the alloys did survive extended aging and cycling depending upon the substrate-alloy combinations.
Evaluation of the Strength of Interface for Multi-Layered Materials in Photonic Devices
Authors: Koguchi Hideo , Kimura Naoki
Published: November 2015

Recent electronic device packaging, for instance, CSP has a bonded structure of IC chip and polymers, and delamination occurs frequently at the interface between IC and a resin. Furthermore, thermal stresses which are caused by a temperature variation in the bonding process of CSP and heat cycles for environment temperature will influence on the strength of interface. In the present paper, the delamination test for specimens with different thicknesses of an interlayer is carried out to investigate the strength of multi-layered joints, and the critical value for the intensity of singularity at delamination of interface is determined through a numerical analysis using a boundary element analysis. In experiment, a silicon wafer is joined with a silicon-on-sapphire (SOS) plate by a resin. The SOS is composed of silicon film and sapphire plate. The joining strength in silicon, resin and SOS joints with a rectangular bonding area is investigated. The bonded specimens are prepared under different cooling rate. Load is applied to the specimen so as to delaminate at the interfaces of silicon film and sapphire. Delamination occurs at the interface between silicon film and sapphire plate in the specimen. Nominal stress for delamination is about 2.23–3.59 MPa. From a comparison of the strength of joint for rapid and slow cooling conditions, it is found that the residual stress reduces the strength of joint. In the numerical analysis, the intensity of singularity at the corner of interface for a unit load is determined. The intensity of singularity at the corner of the interface is related to the intensities of singularity in the radial direction and on the angle from the side free surface. The critical intensity of singularity for delamination of the interface is obtained by multiplying the force at delamination. Then, the critical intensity of singularity is determined as 168 MPa•mm0.18 regardless of the thickness of silicon film.
Numerical Simulation of Advanced Monolithic Microcooler Designs for High Heat Flux Microelectronics
Authors: Scholl Sebastian , Gorle Catherine , Houshmand Farzad , Liu Tanya , Lee Hyoungsoon , Won Yoonjin , Asheghi Mehdi , Goodson Kenneth , Kazemi Hooman
Published: November 2015

This study considers CFD simulations with conjugate heat transfer performed in the framework of designing a complex micro-scale cooling geometry. The numerical investigation of the three-dimensional, laminar flow (Reynolds number smaller than 480) and the solid conduction is done on a reduced model of the heat sink micro-structure to enable exploring a variety of configurations at a limited computational cost. The reduced model represents a unit-cell, and uses periodic and symmetry boundary conditions to mimic the conditions in the entire cooling manifold. A simulation of the entire heat sink micro-structure was performed to verify the unit-cell set-up, and the comparison demonstrated that the unit-cell simulations allow reducing the computational cost by two orders of magnitude while retaining accurate results. The baseline design for the unit-cell represents a configuration used in traditional electronic heat sinks, i.e. a simple channel geometry with a rectangular cross section, with a diameter of 50 μm, where the fluid flows between two cooling fins. Subsequently three types of modified geometries with feature sizes of 50 μm were considered: baffled geometries that guide the flow towards the hotspot region, geometries where the fins are connected by crossbars, and a woodpile structure without cooling fins. Three different mass-flow rates were tested. Based on the medium mass-flow rate considered, the woodpile geometry showed the highest heat transfer coefficient with an increase of 70% compared to the baseline geometry, but at the cost of increasing the pressure drop by more than 300%. The crossbar geometries were shown to be promising configurations, with increases in the heat transfer coefficient of more than 20% for a 70% increase in pressure drop. The potential for further optimization of the crossbar configurations by adding or removing individual crossbars will be investigated in a follow up study. The results presented demonstrate the increase in performance that can be obtained by investigating a variety of designs for single phase cooling devices using unit-cell conjugate heat transfer simulations.
Numerical Optimization of Advanced Monolithic Microcoolers for High Heat Flux Microelectronics
Authors: Scholl Sebastian , Gorle Catherine , Houshmand Farzad , Asheghi Mehdi , Goodson Kenneth , Verstraete Tom
Published: November 2015

This study considers the optimization of a complex micro-scale cooling geometry that represents a unit-cell of a full heat sink microstructure. The configuration consists of a channel with a rectangular cross section and a hydraulic diameter of 100 μm, where the fluid flows between two cooling fins connected by rectangular crossbars (50 × 50 μm). A previous investigation showed that adding these crossbars at certain locations in the flow can increase the heat transfer in the microchannel, and in the present work we perform an optimization to determine the optimal location and number of crossbars. The optimization problem is defined using 12 discrete design parameters, which represent 12 crossbars at different locations in the channel that can either be turned off and become part of the fluid domain, or turned on and become part of the solid domain. The optimization was done using conjugate heat transfer computational fluid dynamics (CFD) simulations using Fluent 15.0. All possible 4096 configurations were simulated for one set of boundary conditions. The domain was discretized using about 1 million nodes combined for the fluid and solid domains and the computational time was around 1 CPU hour per case. The results show that further improvements in heat transfer are feasible at an optimized pressure drop. The results cover a range of pressure drops from 25 kPa to almost 90 kPa and the heat transfer coefficient varies from 60 to 120 kW/m2K. The configurations on the Pareto front show the trend that crossbars closer to the maximal fluid-solid interface result in a more optimal performance than crossbars positioned farther away. In addition to performing simulations for all possible configurations, the potential of using a genetic algorithm to identify the configurations that define the Pareto front was explored, demonstrating that a 80% reduction in computational time can be achieved. The results of this study demonstrate the significant increase in performance that can be obtained through the use of computational tools and optimization algorithms for the design of single phase cooling devices.
A Microfluidic-Based Tactile Sensor for 3-DOF Force/Torque Detection
Authors: Yang Yichao , Hao Zhili
Published: November 2015

This paper reports on a microfluidic-based tactile sensor capable of detecting forces along two directions and torque about one direction. The 3-Degree-Of-Freedom (3-DOF) force/torque sensor encompasses a symmetric three-dimensional (3D) microstructure embedded with two sets of electrolyte-enabled distributed resistive transducers underneath. The 3D microstructure is built into a rectangular block with a loading-bump on its top and two microchannels at its bottom. Together with electrode pairs distributed along the microchannel length, electrolyte in each microchannel functions as a set of three resistive transducers. While a normal force results in a resistance increase in the two sets of transducers, a shear force causes opposite resistance changes in the two sets of transducers. Conversely, a torque leads to the opposite resistance changes in the two side transducers in each set. Soft lithography and CNC molding are combined to fabricate a prototype tactile sensor. The experimental results validate the feasibility of using this microfluidic-based tactile sensor for 3-DOF force/torque detection.
A Miniature Double Oscillating-Fan Cooling System Using Electromagnetic Force
Authors: Su Hsien-Chin
Published: November 2015

In this study, an oscillating-fan cooling device using electromagnetic force has been proposed. The device consists of two oscillating-fans flapping back and forth. It requires only one electromagnet and two elastic blades with one magnet on each of them. The electromagnet and two elastic blades are situated on a base and arranged accordingly. And thus, the electromagnetic force generated by the electromagnet can actuate the blades. The main advantage of this cooling device compared to a rotary fan is its simple structure because there is no bearing and motor in the cooling device. Moreover, the simplicity of the device makes it a highly reliable and low cost cooling device. The driving current can be either DC PWM or AC under 8 V – 12 V so it is compatible to most electronic devices. The dimensions of the cooling device can be designed as small as 20 mm (L) * 30 mm (W) * 4 mm (H) and as large as 60 mm * 55 mm * 25 mm. For a cooling experiment, three cooling devices with the dimension of 50 mm * 50 mm * 15 mm were incorporated with a heat sink with the dimension of 190 mm * 110 mm * 15 m. The dummy heater dissipated 55W while the environmental temperature is 44.8 °C. The result showed that the dummy heater can be cooled from 120.7 °C to 69.3 °C while the total power consumption of the three cooling devices is 1.74 W. The result shows that the cooling device not only provides an outstanding cooling ability but also shows a great potential for structural reliability and design flexibility.
Understanding the True Total Cost of Ownership of Water Cooling for Data Centers
Authors: Demetriou Dustin W. , Kamath Vinod , Mahaney Howard
Published: November 2015

The generation-to-generation IT performance and density demands continue to drive innovation in data center cooling technologies. For many applications, the ability to efficiently deliver cooling via traditional chilled air cooling approaches has become inadequate. Water cooling has been used in data centers for more than 50 years to improve heat dissipation, boost performance and increase efficiency. While water cooling can undoubtedly have a higher initial capital cost, water cooling can be very cost effective when looking at the true lifecycle cost of a water cooled data center.

This study aims at addressing how one should evaluate the true total cost of ownership for water cooled data centers by considering the combined capital and operational cost for both the IT systems and the data center facility. It compares several metrics, including return-on-investment for three cooling technologies: traditional air cooling, rack-level cooling using rear door heat exchangers and direct water cooling via cold plates. The results highlight several important variables, namely, IT power, data center location, site electric utility cost, and construction costs and how each of these influence the total cost of ownership of water cooling. The study further looks at implementing water cooling as part of a new data center construction project versus a retrofit or upgrade into an existing data center facility.