bluuebunny/crossref_metadata_2025 huggingface dataset:
The Virtual Worlds Project: geological mapping and field skills
Authors: Houghton Jacqueline J. , Lloyd Geoffrey E. , Robinson Annabeth , Gordon Clare E. , Morgan Daniel J.
Published: November 2015

The Virtual Worlds Project is a UK collaboration between the School of Earth and Environment, University of Leeds, and the Leeds College of Art, to build a virtual environment in which to learn and practice basic geological mapping skills. Using the Unity game engine, a virtual landscape populated by rock outcrops with associated notebook entries has been created. This approach is not a replacement for field map work. Rather, it represents an in‐class tool with the appearance of a computer game with which to enhance basic mapping skills taught in the field in a virtual environment.
Development and Validation of a Four‐Item Migraine Screening Algorithm Among a Nonclinical Sample: The Migraine‐4
Authors: Walters A. Brooke , Smitherman Todd A.
Published: November 2015

Objectives

The present study sought to develop and validate a screening algorithm from the ICHD‐3 beta diagnostic criteria for migraine utilizing a nonclinical sample. The goal was to determine the most sensitive and specific symptoms for differentiating migraine from other headache disorders and to validate the derived symptom algorithm as a screening measure.

Background

Despite its prevalence and impact, migraine remains under‐recognized and under‐treated. The U.S. Headache Consortium recommended development and dissemination of validated screening measures as a means to improve diagnosis.

Methods

Participants were 1829 young adults (71.5% female; 74.4% white; mean age = 19.09 years [SD = 2.05]) who reported headache via computerized diagnostic interview. From this group, 158 were found to have ICHD episodic or chronic migraine and were randomly split into experimental and holdout validation samples. Within the experimental sample, receiver operating characteristic (ROC) curve data were obtained for each candidate symptom (item); backward stepwise logistic regression analysis was performed among the items with the most predictive likelihood ratios to determine the optimal model for differentiating migraine from non‐migrainous headache. The retained four‐symptom algorithm was then validated among the holdout sample, in which various cutoff points were compared to gold standard diagnosis via ROC curve estimations to determine the optimal operating point (OOP) of the algorithm as a screening measure.

Results

Attack duration of 4‐72 hours (100% [95% CI = 95‐100%]), severity ≥ 5 (91% [82‐97%]), photophobia (90% [80‐96%]), and phonophobia (90% [80‐96%]) showed the highest sensitivity, while vomiting (98% [96‐99%]), duration of 4‐72 hours (92% [90‐94%]), nausea (89% [86‐91%]), and headache‐related disability (88% [85‐91%]) showed the highest specificity. The optimal retained model (Migraine‐4) included: duration of 4‐72 hours, nausea, photophobia, and phonophobia. Among the holdout validation sample, the OOP was positive endorsement of three out of four symptoms, which had a sensitivity of 94% (95% CI = 87‐98%), a specificity of 92% (90‐94%), and an area under the curve of 93% (90‐96%; +LR = 12.37, −LR = 0.06, PPV = 67%, NPV = 99%).

Conclusions

The optimal model shares some similarities with previous models but performed better than prior screeners at differentiating migraine from other headache presentations. The Migraine‐4 has utility in identifying migraine among nonclinical and young adult samples. Further research with this measure is warranted to determine its utility with treatment‐seeking patients and validity in direct comparison to established screening instruments.
A Motion Simulator Ride Associated With Headache and Subdural Hematoma: First Case Report
Authors: Scranton Robert A. , Evans Randolph W. , Baskin David S.
Published: November 2015

We report the first case report of symptomatic bilateral subdural hematomas (SDH) associated with riding a centrifugal motion simulator ride. A previously healthy 55‐year‐old male developed new onset daily headaches 1 week after going on the ride that were due to symptomatic bilateral SDH requiring operative intervention with a full recovery. There was no history of other trauma or other systemic or intracranial abnormality to account for the development of the SDH.

We review the headaches and other clinical features associated with chronic SDH. Twelve cases of roller coaster headaches due to SDH associated with riding roller coasters have been reported. The pathophysiology is reviewed, which we believe is the same mechanism that may be responsible in this case. Although it is possible that this neurovascular injury is truly rare, it is also possible that this injury is underreported as patients and physicians may not make the association or physicians have not reported additional cases. The risk of this injury likely increases with age, as the size of the subdural space increases, and may support the maxim that “roller coasters and simulators are for kids.”
An efficient empirical Bayes method for genomewide association studies
Authors: Wang Q. , Wei J. , Pan Y. , Xu S.
Published: November 2015

Linear mixed model (LMM) is one of the most popular methods for genomewide association studies (GWAS). Numerous forms of LMM have been developed; however, there are two major issues in GWAS that have not been fully addressed before. The two issues are (i) the genomic background noise and (ii) low statistical power after Bonferroni correction. We proposed an empirical Bayes (EB) method by assigning each marker effect a normal prior distribution, resulting in shrinkage estimates of marker effects. We found that such a shrinkage approach can selectively shrink marker effects and reduce the noise level to zero for majority of non‐associated markers. In the meantime, the EB method allows us to use an ‘effective number of tests’ to perform Bonferroni correction for multiple tests. Simulation studies for both human and pig data showed that EB method can significantly increase statistical power compared with the widely used exact GWAS methods, such as GEMMA and FaST‐LMM‐Select. Real data analyses in human breast cancer identified improved detection signals for markers previously known to be associated with breast cancer. We therefore believe that EB method is a valuable tool for identifying the genetic basis of complex traits.
Modular Upgradability in Consumer Electronics: Economic and Environmental Implications
Authors: Agrawal Vishal V. , Atasu Atalay , Ülkü Sezer
Published: November 2015

Modularly upgradable product designs have been advocated to offer environmental and economic advantages; however, they are not commonly used in the consumer electronics industry. In this article, we investigate the economic and environmental benefits and challenges of modular upgradability for consumer electronics. From an economic point of view, we posit that the limited adoption of modular upgradability in consumer electronics is owing to various demand‐, technology‐, and competition‐related issues. From an environmental point of view, we posit that modularly upgradable product designs may not necessarily lead to superior environmental outcomes. To reach meaningful conclusions regarding the environmental benefits of modular upgradability, one needs to understand how product architecture affects demand, production, and consumption patterns, which arise from endogenous consumer and manufacturer choices. It is also important to take into account that modular upgradability may have potentially differentiated effects in the production, consumption, and postuse phases of the lifecycle.
Patulin is a cultivar‐dependent aggressiveness factor favouring the colonization of apples by Penicillium expansum
Authors: Snini Selma P. , Tannous Joanna , Heuillard Pauline , Bailly Sylviane , Lippi Yannick , Zehraoui Enric , Barreau Christian , Oswald Isabelle P. , Puel Olivier
Published: November 2015

The blue mould decay of apples is caused by Penicillium expansum and is associated with contamination by patulin, a worldwide regulated mycotoxin. Recently, a cluster of 15 genes (patA–patO) involved in patulin biosynthesis was identified in P. expansum. blast analysis revealed that patL encodes a Cys6 zinc finger regulatory factor. The deletion of patL caused a drastic decrease in the expression of all pat genes, leading to an absence of patulin production. Pathogenicity studies performed on 13 apple varieties indicated that the PeΔpatL strain could still infect apples, but the intensity of symptoms was weaker compared with the wild‐type strain. A lower growth rate was observed in the PeΔpatL strain when this strain was grown on nine of the 13 apple varieties tested. In the complemented PeΔpatL:patL strain, the ability to grow normally in apple and the production of patulin were restored. Our results clearly demonstrate that patulin is not indispensable in the initiation of the disease, but acts as a cultivar‐dependent aggressiveness factor for P. expansum. This conclusion was strengthened by the fact that the addition of patulin to apple infected by the PeΔpatL mutant restored the normal fungal colonization in apple.
Distribution, species composition and relative abundances of sandflies in North Waziristan Agency, Pakistan
Authors: ALI N. , ULLAH A. , WAHID S. , KHISROON M. , RASHEED S. B.
Published: November 2015

This study was conducted to investigate the diversity of sandflies (Psychodidae: Phlebotominae) and the incidence of leishmaniasis in three villages of North Waziristan Agency, Pakistan. Sandflies were sampled monthly during 2012, at dusk and dawn, in selected indoor habitats including both bedrooms and animal sheds using a knock‐down spray catch method. A total of 3687 sandflies were collected, including 1444 individuals in Drezanda, 1193 in Damdil and 1050 in Dattakhel. This study revealed 14 species of two genera,Phlebotomus(Phlebotomus sergenti,Phlebotomus papatasi,Phlebotomus caucasicus,Phlebotomus kazeruni,Phlebotomus alexandriandPhlebotomus salehi) andSergentomyia(Sergentomyia dentate,Sergentomyia baghdadis,Sergentomyia babu,Sergentomyia theodori,Sergentomyia sumbarica,Sergentomyia dreyfussitur kestanica,Sergentomyia hogsoni pawlowskyiandSergentomyia fallax afghanica) (both: Diptera: Psychodidae).Phlebotomus sergentiwas the most abundant species (42.1%), followed byS. dentata(17.7%) andS. baghdadis(17.4%). The number of males collected represented about twice that of female flies, and the maximum number was collected in July, followed by August. The determination of the species composition of sandfly populations, seasonal variations, relative abundances and estimations of infection in the vector population may provide information about the dynamics of leishmaniasis transmission that is useful in planning vector control activities.
Should foods or nutrients be the focus of guidelines to promote healthful eating?
Authors: Green H.
Published: November 2015

A variety of different dietary patterns can achieve the nutrient goals for a given population and therefore be considered as healthful. This means that guidelines for a healthy diet can be tailored to suit different cultures and food preferences. Although food‐based dietary guidelines are used worldwide, there is also authoritative dietary advice in relation to single nutrients, especially those of public health relevance. This includes recommendations to eat less salt, free sugars and ‘saturates’ as well as more fibre. However, it can be difficult for consumers to make simultaneous reductions in salt, sugars and saturated fatty acids as well as increases in dietary fibre, given that food choices are made according to a variety of considerations, including taste preferences, culture, convenience and cost, as well as health. In addition, media coverage of new scientific findings, especially those that challenge current dietary guidelines, can confuse consumers and hamper efforts to eat healthfully. Both food‐based dietary guidelines and recommended nutrient intakes can help consumers eat healthfully, providing they are supported by sound nutrition science, communicated well and delivered in a way that promotes beneficial changes in behaviour.
Moving up! Mapping careers in nutrition
Authors: McConkey V.
Published: November 2015

Good nutrition is fundamental to maintaining a healthy body and mind, enabling each of us to live longer, healthier lives. For those interested in taking steps to progress a career in nutrition and dietetics, an increasing number of opportunities are available. Yet knowing where to start and how to navigate the diversity of options available can be complex. In November 2014, the Association for Nutrition (AfN) and Nutritionists in Industry (NII) group held a career seminar for mid‐career nutritionists at the Food Matters Live conference, London. Established nutrition and dietetic professionals spoke to attendees about career paths, education, specialisms and geographical responsibilities. Challenges facing those working in this rewarding field were also addressed, including expanding responsibility, moving to a new organisation, managing work–life balance and coping with restructure or redundancy. Attendees also learnt about the regulatory role of the UK Voluntary Register of Nutritionists (UKVRN), held by the AfN, in protecting the public from unsafe practice and the importance of shared ethical standards, scientific integrity and commitment to public protection.
Effectiveness of simulation with team‐based learning in newborn nursing care
Authors: Kang Kyung‐Ah , Kim Shin‐Jeong , Oh Jina , Kim Sunghee , Lee Myung‐Nam
Published: November 2015

This study determines the effect of simulation with team‐based learning (TBL) on newborn nursing care. This randomized controlled trial included 74 nursing students from one university located in Seoul, South Korea. Participants were categorized into two groups according to educational modality: one group involved both simulation and TBL, and the other involved simulation alone. Learning attitudes, academic achievement, and simulation performance were examined to assess effectiveness. The mean difference in learning attitudes between the two groups was non‐significant. Low academic achievement differed significantly between the two groups (t = 3.445, P = 0.002). There was no significant difference in mean scores for simulation performance between the two groups. In this study, simulation with TBL was effective in improving learning outcomes. In current nursing education, various learning methods are employed within complex nursing situations and require flexibility and problem‐solving approaches.
Do Intentions Set Up Rational Defaults? Commitments, Reasons, and the Diachronic Dimension of Rationality
Authors: Gillessen Jens
Published: November 2015

Suppose that you do not do what you have previously decided to do. Are you to be charged with irrationality? A number of otherwise divergent theories of practical rationality hold that by default, you are; there are rational pressures, it is claimed, that favor the long‐term stability and eventual execution of distal intentions. The article challenges this view by examining how these purported pressures can be spelled out. Is intention a normative commitment to act? Are intentions reasons for action – or at least for retaining one's intention until the time to act has come? Or is the rationality of ‘doing as you decide’ governed by diachronic wide‐scope norms, as Michael Bratman and John Broome suggest? All of these approaches are shown to raise severe problems, which suggests a more modest view: diachronic pressures on intending are at each point in time confined to the very next instant.
The CDKN2A/p16INK4a 5′UTR sequence and translational regulation: impact of novel variants predisposing to melanoma
Authors: Andreotti Virginia , Bisio Alessandra , Bressac‐de Paillerets Brigitte , Harland Mark , Cabaret Odile , Newton‐Bishop Julia , Pastorino Lorenza , Bruno William , Bertorelli Roberto , De Sanctis Veronica , Provenzani Alessandro , Menin Chiara , Fronza Gilberto , Queirolo Paola , Spitale Robert C. , Bianchi‐Scarrà Giovanna , Inga Alberto , Ghiorzo Paola
Published: November 2015

Many variants of uncertain functional significance in cancer susceptibility genes lie in regulatory regions, and clarifying their association with disease risk poses significant challenges. We studied 17 germline variants (nine of which were novel) in the CDKN2A 5′UTR with independent approaches, which included mono and bicistronic reporter assays, Western blot of endogenous protein, and allelic representation after polysomal profiling to investigate their impact on CDKN2A mRNA translation regulation. Two of the novel variants (c.‐27del23, c.‐93‐91delAGG) were classified as causal mutations (score ≥3), along with the c.‐21C>T, c.‐34G>T, and c.‐56G>T, which had already been studied by a subset of assays. The novel c.‐42T>A as well as the previously described c.‐67G>C were classified as potential mutations (score 1 or 2). The remaining variants (c.‐14C>T, c.‐20A>G, c.‐25C>T+c.‐180G>A, c.‐30G>A, c.‐40C>T, c.‐45G>A, c.‐59C>G, c.‐87T>A, c.‐252A>T) were classified as neutral (score 0). In conclusion, we found evidence that nearly half of the variants found in this region had a negative impact on CDKN2A mRNA translation, supporting the hypothesis that 5′UTR can act as a cellular Internal Ribosome Entry Site (IRES) to modulate p16INK4a translation.
Piriformospora indica reduces fusarium head blight disease severity and mycotoxin DON contamination in wheat under UK weather conditions
Authors: Rabiey M. , Shaw M. W.
Published: November 2015

Piriformospora indica (Sebacinaceae) is a cultivable root endophytic fungus. It colonizes the roots of a wide range of host plants. In many settings colonization promotes host growth, increases yield and protects the host from fungal diseases. Evaluation was made of the effect of P. indica on fusarium head blight (FHB) disease of winter (cv. Battalion) and spring (cv. Paragon, Mulika, Zircon, Granary, KWS Willow and KWS Kilburn) wheat and consequent contamination by the mycotoxin deoxynivalenol (DON) under UK weather conditions. Interactions of P. indica with an arbuscular mycorrhizal fungus (Funneliformis mosseae), fungicide application (Aviator Xpro) and low and high fertilizer levels were considered. Piriformospora indica application reduced FHB disease severity and incidence by 70%. It decreased mycotoxin DON concentration of winter and spring wheat samples by 70 and 80%, respectively. Piriformospora indica also increased aboveground biomass, 1000‐grain weight and total grain weight. Piriformospora indica reduced disease severity and increased yield in both high and low fertilizer levels. The effect of P. indica was compatible with F. mosseae and foliar fungicide application. Piriformospora indica did not have any effects on plant tissue nutrients. These results suggest that P. indica might be useful in biological control of Fusarium diseases of wheat.
The Other Side of the Coin: NGOs, Rights‐Based Approaches, and Public Administration
Authors: Schmitz Hans Peter , Mitchell George E.
Published: November 2015

The majority of the world's population resides in low‐ and middle‐income countries, where the problem of sustainable development is among the most pressing public administration challenges. As principal actors within the international development community, transnational nongovernmental organizations (NGOs) play a leading role in piloting a wide variety of development‐focused strategies. During the past decade, many of these transnational NGOs, along with the United Nations, have embraced a rights‐based approach (RBA) to development as an alternative to traditional service delivery. Despite the growing popularity of RBA among NGOs and other development actors, surprisingly little attention has been paid to understanding the significance of RBA for public administration and for public managers—the “other side of the coin.” Drawing on current research in NGO studies and international development, this article describes several varieties of contemporary rights‐based approaches, analyzes their impact on development practices, and examines the intersection of RBA and public administration.
Can Minimum Wages Close the Gender Wage Gap?
Authors: Hallward‐Driemeier Mary , Rijkers Bob , Waxman Andrew
Published: November 2015

Using manufacturing plant‐level census data, this paper demonstrates that minimum wage increases in Indonesia reduced gender wage gaps among production workers, with heterogeneous impacts by level of education and position of the firm in the wage distribution. Paradoxically, educated women appear to have benefitted the most, particularly in the lower half of the firm average earnings distribution. By contrast, women who did not complete primary education did not benefit on average, and even lost ground in the upper end of the earnings distribution. Minimum wage increases were thus associated with exacerbated gender pay gaps among the least educated, and reduced gender gaps among the best educated production workers. Unconditional quantile regression analysis attests to wage compression and lighthouse effects. Changes in relative employment prospects were limited.
When More Does Not Necessarily Mean Better: Health‐Related Illfare Comparisons with Non‐Monotone Well‐Being Relationships
Authors: Apablaza Mauricio , Bresson Florent , Yalonetzky Gaston
Published: November 2015

Most welfare studies assume that well‐being is monotonically related to the variables used for the analysis. While this assumption is reasonable for many dimensions of well‐being like income, education, or empowerment, there are some cases where it is definitively not relevant, in particular with respect to health. For instance, health status is often proxied using the Body Mass Index (BMI). Low BMI values can capture undernutrition or the incidence of severe illness, yet a high BMI is neither desirable as it indicates obesity. Usual illfare indices derived from poverty measurement are then not appropriate. This paper proposes illfare indices that are consistent with some situations of non‐monotonic well‐being relationships and examines the partial orderings of different distributions derived from various classes of illfare indices. An illustration is provided for child health as proxied by a weight‐for‐age indicator using DHS data for Bangladesh, Colombia and Egypt during the last few decades.
Caring in an atmosphere of uncertainty: perspectives and experiences of caregivers of peoples undergoing haemodialysis in Iran
Authors: Rabiei Leili , Eslami Ahmad Ali , Abedi HeidarAli , Masoudi Reza , Sharifirad Gholam Reza
Published: November 2015

Background

Chronic renal failure is one of the major causes of mortality and disability worldwide. Although dialysis treatment is considered as a life‐saving treatment for these patients, their caregivers face various problems making the atmosphere of caring uncertain.

Aims

This study is aimed to explore and describe the experiences and perspectives of family caregivers of the patients undergoing haemodialysis.

Methods

In this study, 20 haemodialysis family caregivers were selected by purposeful sampling. Data gathering techniques in this research were in‐depth and unstructured interview and field observation. The researchers used an inductive thematic analysis approach to analysing the interviews' data.

Findings

Three main themes emerged from the data indicating the patients' care are conducted in a state of uncertainty including constant struggle to learn, effort and adherence to the divine thread, and in disease's captivity.

Conclusions

Caring in an uncertain atmosphere leads to decreased efficiency and quality of family caregivers' care. To promote and improve the efficiency of care, healthcare planners should pay attention to the challenges and perspectives of caregivers of the patients undergoing haemodialysis.
Along paths converging to Bengt Saltin's early contributions in exercise physiology
Authors: Schantz P.
Published: November 2015

A fascinating chain of events led in 1941 to the formation of the Department of Physiology at the Royal Gymnastic Central Institute (GCI) in Stockholm, Sweden. Erik Hohwü Christensen, from the scientifically advanced Lindhard School in Copenhagen became its first professor. A central research question for him concerned determining the limiting factors for maximal physical performance in man. This was the academic setting where the sports interested medical student Bengt Saltin was introduced to exercise physiology. In the summer of 1959, he became involved in a study on intermittent vs continuous running. A doctoral project, with Per‐Olof Åstrand as his tutor, resulted in 1964 as the thesis “Aerobic work capacity and circulation at exercise in man. With special reference to the effect of prolonged exercise and/or heat exposure”. In the decade that followed, Saltin continued along that path. However, he also added a vital research line involving pioneering studies on skeletal muscles in the exercising man, a series of novel studies on the physiological demands in various sports, and studies of the effects of physical training within the general population.
Muscle adaptation to exercise: New Saltin’s paradigms
Authors: Booth F. W.
Published: November 2015

The title assigned for my lecture at the Saltin Symposium was “Muscle adaptation to exercise: new paradigms.” The title's topic made me remember that some of Saltin's paradigms for his development of a novel exercise model were either originated by him or modified by him from existing information. Therefore, I deemed it would be instructive for future generations to consider one facet of his 54‐year career – human exercise models. I arbitrarily selected to share five examples of new paradigm models initiated by Saltin. They are: bed rest; arms vs legs; one leg vs the other leg; myokine communication from skeletal muscle to other organs/tissues; and 42‐day cross‐country skiing expedition. I arbitrarily selected the above as examples of novel approaches that he used to the study humans during maximal endurance exercise. Noteworthy though is that Saltin's lifetime demeanor, itself, is a model for other scientists. In final analysis, the world is richer due to his passion to study humans to advance medical science by uncovering mechanisms as to how the human body is constructed to perform endurance types of exercise at maximal intensities and durations.
Reflex control of the circulation during exercise
Authors: Fadel P. J.
Published: November 2015

Appropriate cardiovascular and hemodynamic adjustments are necessary to meet the metabolic demands of working skeletal muscle during exercise. Alterations in the sympathetic and parasympathetic branches of the autonomic nervous system are fundamental in ensuring these adjustments are adequately made. Several neural mechanisms are responsible for the changes in autonomic activity with exercise and through complex interactions, contribute to the cardiovascular and hemodynamic changes in an intensity‐dependent manner. This short review is from a presentation made at the Saltin Symposium June 2–4, 2015 in Copenhagen, Denmark. As such, the focus will be on reflex control of the circulation with an emphasis on the work of the late Dr. Bengt Saltin. Moreover, a concerted effort is made to highlight the novel and insightful concepts put forth by Dr. Saltin in his last published review article on the regulation of skeletal muscle blood flow in humans. Thus, the multiple roles played by adenosine triphosphate (ATP) including its ability to induce vasodilatation, override sympathetic vasoconstriction and stimulate skeletal muscle afferents (exercise pressor reflex) are discussed and a conceptual framework is set suggesting a major role of ATP in blood flow regulation during exercise.
Rapid hepatic perfusion decellularization: technique and critique
Authors: Fathi Ibrahim , Elhammady Habashi , Sakr Mahmoud , Nabawi Ayman , Marei Mona
Published: November 2015

Background

Organ shortage facing the increasing success of liver transplantation has provoked research into the utilization of animal organs for clinical transplantation. The technique of whole‐organ decellularization aims at the removal of the antigenic cellular content, thus evading the immune rejection cascade and the production of complex three‐dimensional extracellular matrices of the entire organs with preservation of their intrinsic vascular networks rendering them transplantable. The aim of this study was the production of decellularized rabbit liver matrices by applying a simple, rapid perfusion decellularization technique and their characterization (both qualitatively and quantitatively).

Materials and methods

Decellularization of the caudate hepatic lobes of New Zealand white rabbits (n = 22) was achieved through sequential perfusion of the portal venous system with deionized water, 0.8% Triton X‐100 and 0.8% sodium dodecyl sulphate (SDS). Decellularized specimens were characterized both qualitatively (histology, fluoroscopy, corrosion casting and scanning electron microscopy) and quantitatively (total collagen assay [colorimetric] and total DNA assay [Hoechst 33258]). A Student's t‐test was used to compare quantitative laboratory results before and after decellularization. A probability (P) value of <0.05 was considered significant.

Results

Effective decellularization was achieved as proven by histology and quantitative assessment (DNA remnants <1.5%, P = 0.0009), while preserving 68% of the total collagen content (P = 0.003). Portal vascular network integrity was confirmed by fluoroscopy and corrosion casting. Scanning electron microscopy also confirmed the preservation of the three‐dimensional architecture.

Conclusions

Liver perfusion decellularization technique using both 0.8% Triton X‐100 and 0.8% SDS is a simple and rapid technique, yielding efficiently decellularized liver matrices preserving their vascular integrity, 3D architecture and 68% of total collagen content.
Key Technologies to Implement High Thermal Ambient Data Center
Authors: Zhang Shu , Han Yu , Ahuja Nishi , Liu Xiaohong , Ren Huahua , Guo Guangliang
Published: November 2015

In recent years, the internet services industry has been developing rapidly. Accordingly, the demands for compute and storage capacity continue to increase and internet data centers are consuming more power than ever before to provide this capacity. Based on the Forest & Sullivan market survey, data centers across the globe now consume around 100GWh of power and this consumption is expected to increase 30% by 2016. With development expanding, IDC (Internet Data Center) owners realize that small improvements in efficiency, from architecture design to daily operations, will yield large cost reduction benefits over time.

Cooling energy is a significant part of the daily operational expense of an IDC. One trend in this industry is to raise the operational temperature of an IDC, which also means running IT equipment at HTA (Higher Ambient Temperature) environment. This might also include cooling improvements such as water-side or air-side economizers which can be used in place of traditional closed loop CRAC (Computer room air conditioner) systems. But just raising the ambient inlet air temperature cannot be done by itself without looking at more effective ways of managing cooling control and considering the thermal safety.

An important trend seen in industry today is customized design for IT (Information Technology) equipment and IDC infrastructure from the cloud service provider. This trend brings an opportunity to consider IT and IDC together when designing and IDC, from the early design phase to the daily operation phase, when facing the challenge of improving efficiency. This trend also provides a chance to get more potential benefit out of higher operational temperature. The advantages and key components that make up a customized rack server design include reduced power consumption, more thermal margin with less fan power, and accurate thermal monitoring, etc. Accordingly, the specific IDC infrastructure can be re-designed to meet high temperature operations.

To raise the supply air temperature always means less thermal headroom for IT equipment. IDC operators will have less responses time with large power variations or any IDC failures happen. This paper introduces a new solution called ODC (on-demand cooling) with PTAS (Power Thermal Aware Solution) technology to deal with these challenges. ODC solution use the real time thermal data of IT equipment as the key input data for the cooling controls versus traditional ceiling installed sensors. It helps to improve the cooling control accuracy, decrease the response time and reduce temperature variation. By establishing a smart thermal operation with characteristics like direct feedback, accurate control and quick response, HTA can safely be achieved with confidence. The results of real demo testing show that, with real time thermal information, temperature oscillation and response time can be reduced effectively.
A Method to Eliminate the Effect of Phosphor Sedimentation on LED’s Angular Color Uniformity
Authors: Chen Qi , Hu Run , Wang Yiman , Zheng Huai , Luo Xiaobing
Published: November 2015

Phosphor sedimentation has a great impact on the LED’s correlated color temperature (CCT) and the angular color uniformity (ACU). But fewer solutions have been proposed to overcome this effect. In this paper, we analysed the fundamental mechanism behind the phosphor sedimentation effect on LED’s ACU and proposed a simple structure to eliminate the effect. Monte Carlo ray-tracing simulations were conducted to validate the idea. The results show that the maximum CCT deviation with the proposed structure is within 100 K while that of the conventional one is as high as 680 K, and the ACU increases from 0.8811 to 0.9809 by 11.33%. It is concluded that this proposed structure has potential to be used to eliminate the phosphor sedimentation effect.
Intrinsic Thermal Conductivity of Wurtzite AlxGa1-xN, InxGa1-xN and InxAl1-xN From First-Principles Calculation
Authors: Ma Jinlong , Huang Baoling , Li Wu , Luo Xiaobing
Published: November 2015

The thermal conductivities of the alloys of wurtzite AlN, GaN and InN are usually analyzed with the virtual crystal model based on the values of the constituent compounds. However, latest experiments and calculations reveal that the thermal conductivity of wurtzite InN is about three times larger than the previously used value. Thus it is necessary to reanalyze the thermal conductivities of these alloys. In this work, the intrinsic thermal conductivities of AlxGa1−xN, InxGa1−xN and InxAl1−xN are calculated with first-principles calculations along with the virtual crystal treatment. It is found that the thermal conductivities of these alloys are strongly suppressed even after a small amount of alloying. For instance, the in-plane and out-of-plane thermal conductivities of In0.99Ga0.01 N are 66 Wm−1K−1 and 76 Wm−1K−1 respectively, while they are 40 Wm−1K−1 and 48 Wm−1 K−1 for In0.99Al0.01 N, compared with the corresponding values of 130 Wm−1 K−1 and 145 Wm−1 K−1 for bulk wurtzite InN. When the fraction x varies from 0.2 to 0.8, the thermal conductivities of the alloys do not change much. Additionally, the distribution of mean free path indicates that the size effect can persist up to 10μm for both pure compounds and their alloys at room temperature.
Thermal Solution of High Flux Phased Radar Antenna for Military Application
Authors: Parlak Murat , Yaban Murat
Published: November 2015

In military applications, cooling of high heat flux antenna is a challenging problem considering the thermal, mechanical and limited space requirements. In addition to system cooling, thermal uniformity among the high power amplifiers is one of the main issues that should be taken into account for electrical performance requirements. Cold plate is the main mechanical part of the radar antenna structure where it serves as a cooler and a carrier. Liquid path and fin pattern are critical parts of the cold plate design that needs to be carefully studied. These topics are comprehensively discussed in this work. Finite element method software has been used for CFD and thermal analysis. Although cold plate is designed to cool high heat flux, it is known that there is liquid flow in it which applies some amount of hydraulic pressure. Some precautions are taken to withstand high pressure inside the cold plate. The system solution together with manifold design is examined in this study. The internal pressure drop in cold plate has a direct relation with the manifold design. All these topics are discussed in this work.
Raised Floor Hybrid Cooled Data Center: Effect on Rack Inlet Air Temperatures When In Row Cooling Units are Installed Between the Racks
Authors: Gao Tianyi , Geer James , Tipton Russell , Murray Bruce , Sammakia Bahgat G. , Ortega Alfonso , Schmidt Roger
Published: November 2015

The heat dissipated by high performance IT equipment such as servers and switches in data centers is increasing rapidly, which makes the thermal management even more challenging. IT equipment is typically designed to operate at a rack inlet air temperature ranging between 10 °C and 35 °C. The newest published environmental standards for operating IT equipment proposed by ASHARE specify a long term recommended dry bulb IT air inlet temperature range as 18°C to 27°C. In terms of the short term specification, the largest allowable inlet temperature range to operate at is between 5°C and 45°C. Failure in maintaining these specifications will lead to significantly detrimental impacts to the performance and reliability of these electronic devices. Thus, understanding the cooling system is of paramount importance for the design and operation of data centers. In this paper, a hybrid cooling system is numerically modeled and investigated. The numerical modeling is conducted using a commercial computational fluid dynamics (CFD) code. The hybrid cooling strategy is specified by mounting the in row cooling units between the server racks to assist the raised floor air cooling. The effect of several input variables, including rack heat load and heat density, rack air flow rate, in row cooling unit operating cooling fluid flow rate and temperature, in row coil effectiveness, centralized cooling unit supply air flow rate, non-uniformity in rack heat load, and raised floor height are studied parametrically. Their detailed effects on the rack inlet air temperatures and the in row cooler performance are presented. The modeling results and corresponding analyses are used to develop general installation and operation guidance for the in row cooler strategy of a data center.
The Influence of Nanoparticle Type on the Viscosity of Nanoenhanced Energy Storage Materials
Authors: Hess Kieran , Fleischer Amy S.
Published: November 2015

The use of nanoparticles to improve the thermal properties of low thermal conductivity phase change materials is of significant interest. However, the addition of nanoparticles to a base fluid is known to result in an increase in viscosity. An increase in viscosity can suppress convective currents, reducing overall heat transfer thus it necessary to quantify the impact of nanoparticle addition on the viscosity of a PCM.

In this work nanoparticle enhanced phase change mateirals are synthesized using paraffin and three different types of nanoparticles: exfoliated graphite nanoplatelets (xGNP), multi-walled carbon nanotubes (MWCNT) and herringbone graphite nanofibers (HGNF). The particles are loaded at rates between 0.0024wt% to 0.1wt%. The viscosity is analyzed at temperatures between 60 and 100°C. The influence of temperature, nanoparticle type and nanoparticle loading level on viscosity are presented and discussed.

The results show that for xGNP and HGNF within the operating condition studied here that there is no impact of the nanoparticle addition on the viscosity of the base material. However, the addition of MWCNT is found to increase the viscosity of the base fluid with the impact increasing with loading level.
Thermal Design Analysis of 2.5-D Packages With Analytical TSV Submodels
Authors: Zhang H. Y. , Yan Xiao , Zhu W. H. , Lin Leon
Published: November 2015

2.5-D package with through silicon vias (TSVs) on interposer has been envisioned as the most viable way in heterogeneous integration. In this work, several design approaches are considered in the thermal analysis and enhancements of a 2.5-D package with multi chips on through silicon interposer (TSI), which include overmolding materials, metal slug, lid attachment, pin fin heat sink and fan-driven heat sink cooling. The analysis models consist of two dummy flip chips on a silicon interposer to represent the logic die and memory die, respectively. Package submodels, especially the TSV ones, are analyzed with good modeling accuracy. Package thermal modeling indicates that the thermal conductivity of the epoxy overmolding has minimal effect on the thermal performance of copper slug package. Lid attachment further enhances the thermal performance through peripheral substrate attachment. Both designs largely rely on thermally conductive PCB (4L) to maximize power dissipation. Pin-fin heat sink, made of aluminum, can be mounted on the package top to further minimize thermal resistance and extend the power dissipation beyond 10W. For high power application, fan cooled heat sink is used to reduce excessive heat. Copper based aluminum heat sink can remove the heat of 120W from the bare-die package. Self heating due to high current density through the TSV is analyzed. The proposed analytical expression gives good prediction on the local TSV hot spot. It is demonstrated that a distributed TSV network design provides lower temperature rise, which shall have lower risk of failures and is preferred in practice.
Thermally-Optimum Design of GaN-on-SiC HEMT
Authors: Holloway Caleb A. , Bar-Cohen Avram
Published: November 2015

Three-dimensional finite-element modeling is used to determine the thermally optimum design of a GaN-on-SiC MMIC power amplifier, with a focus on the parametric influence of the thermal boundary resistance (TBR), epitaxial geometry, and dissipated linear power on the HEMT junction temperature rise. A commercial MMIC power amplifier is used to set the baseline geometry and dimensions. It is found that the frequently neglected Thermal Boundary Resistance (TBR), between the GaN and SiC, not only has a significant influence on the maximum junction temperature, but directly influences the thermally-optimal GaN thickness for the HEMT transistor. The thermally-optimal GaN thickness is a balance between spreading, vertical thermal resistance, and the magnitude of the TBR. As a consequence, it is seen the commonly used, submicron l GaN thicknesses approach optimality only when the TBR values are below 10 m2-K/GW. Additionally, it is observed that increasing the gate pitch and substrate thickness helps to diffuse the flow of heat within the substrate before it proceeds into the cooling solution, resulting in an overall decrease in thermal resistance. The numerical results are used to verify the accuracy of an available analytical solution for a surface heat source on an orthotropic multi-layer structure, albeit with assumed temperature-invariant properties, thus enabling use of this relation in scoping and preliminary design calculations.
A Method for Thermal Performance Characterization of Ultra-Thin Vapor Chambers Cooled by Natural Convection
Authors: Patankar Gaurav , Mancin Simone , Weibel Justin A. , Garimella Suresh V. , MacDonald Mark A.
Published: November 2015

Vapor chamber technologies offer an attractive approach for passive cooling in portable electronic devices. Due to the market trends in device power consumption and thickness, vapor chamber effectiveness must be compared with alternative heat spreading materials at ultra-thin form factors and low heat dissipation rates. A test facility is developed to experimentally characterize performance and analyze the behavior of ultra-thin vapor chambers that must reject heat to the ambient via natural convection. The evaporator-side and ambient temperatures are measured directly; the condenser-side surface temperature distribution, which has critical ergonomics implications, is measured using an infrared camera calibrated pixel-by-pixel over the field of view and operating temperature range. The high thermal resistance imposed by natural convection in the vapor chamber heat dissipation pathway requires accurate prediction of the parasitic heat losses from the test facility using a combined experimental and numerical calibration procedure. Solid Metal heat spreaders of known thermal conductivity are first tested, and the temperature distribution is reproduced using a numerical model for conduction in the heat spreader and thermal insulation by iteratively adjusting the external boundary conditions. A regression expression for the heat loss is developed as a function of measured operating conditions using the numerical model. A sample vapor chamber is tested for heat inputs below 2.5 W. Performance metrics are developed to characterize heat spreader performance in terms of the effective thermal resistance and the condenser-side temperature uniformity. The study offers a rigorous approach for testing and analysis of new vapor chamber designs, with accurate characterization of their performance relative to other heat spreaders.
Visualization of Confined Jet Impingement With Boiling Using Time-Resolved Stereo-PIV
Authors: Rau Matthew J. , Guo Tianqi , Vlachos Pavlos P. , Garimella Suresh V.
Published: November 2015

Two-phase liquid-vapor flow field measurements of confined jet impingement with boiling are performed using time-resolved stereo particle image velocimetry (stereo-PIV). A single circular jet of water, impinges normally from a 3.75 mm-diameter orifice onto a submerged circular heat source at an orifice-to-target spacing of 4 jet diameters. The impinging jet outflow including the vapor generated at the heat source are confined between the jet orifice plate and the bottom test section wall. Fluorescent seeding particles (10 μm in diameter) and time-resolved PIV measurements (taken at a sampling rate of 750 Hz) allow for imaging of the instantaneous interactions between the liquid and vapor structures. Liquid-phase velocity vectors within the two-phase flow field (with high vapor fractions) are presented as a function of heat flux at jet Reynolds numbers of 5,000 and 15,000 and contrasted with single-phase flow. The time-resolved measurements are used to highlight the influence of the vapor phase on the liquid flow field. It is found that bubble formation effectively blocks the developing wall-jet flow on the heated surface. The resulting liquid flow field in the confinement gap is dominated by vapor motion rather than by the entrainment from the developing wall jet.