bluuebunny/crossref_metadata_2025 huggingface dataset:
Medical Malpractice Claims Following Incidental Durotomy Due to Spinal Surgery
Authors: Durand Wesley M. , Eltorai Adam E. M. , Shantharam Govind , DePasse John Mason , Kuris Eren O. , Hersey Alicia E. , Palumbo Mark A. , Daniels Alan H.
Published: December 2017

Study Design.

Retrospective cohort study.

Objective.

Analyze medical malpractice verdicts and settlements associated with incidental durotomy.

Summary of Background Data.

Incidental durotomy is a common complication of spine surgery. Although most intraoperative dural tears are repaired without sequelae, persistent Cerebrospinal Fluid leak, infection, or neurological injury can yield adverse outcomes. The medicolegal implications of incidental durotomy are poorly understood.

Methods.

Three separate, large legal databases were queried for cases involving incidental durotomy. Case, plaintiff, procedure, and outcome characteristics were analyzed.

Results.

In total, 48 dural tear-related medical malpractice cases were analyzed. Most cases (56.3%) resulted in a ruling in favor of the defendant physician. Most cases alleged neurological deficits (86.7%). A large majority of cases without neurological sequelae had an outcome in favor of the defendant (83.3%). For cases involving a payment, the average amount was $2,757,298 in 2016 adjusted dollars. Additional surgery was required in 56.3% of cases, a delay in diagnosis/treatment of durotomy was present in 43.8%, and alleged improper durotomy repair was present in 22.9%. A favorable outcome for the plaintiff was more likely in cases with versus without alleged delay in diagnosis/treatment (61.9% vs. 29.6%, P = 0.025) and improper durotomy repair technique (72.7% vs. 35.1%, P = 0.040). Repeat surgery was not associated with favorable outcome for the plaintiff (42.8% cases with reoperation vs. 38.1% without, P = 0.486).

Conclusion.

This analysis of durotomy-associated closed malpractice claims after spine surgery is the largest yet conducted. Durotomy cannot always be considered an entirely benign event, and these findings have several direct implications for clinicians: late-presenting or dehiscent durotomy may be associated with adverse outcomes and subsequent risk of litigation, timely reoperation in the event of durotomy-related complications may not increase surgeon liability, and spine surgeons should be prepared to defend their choice of durotomy repair technique, should dehiscence occur.

Level of Evidence: 3
Corneal Optical Changes Associated with Induced Edema in Fuchs Endothelial Corneal Dystrophy
Authors: Wacker Katrin , McLaren Jay W. , Kane Katrina M. , Patel Sanjay V.
Published: December 2017

Purpose:

Patients with Fuchs endothelial corneal dystrophy (FECD) often notice poor vision in the morning that improves as the day progresses. In this study, we determined changes in corneal optical properties associated with induced corneal edema.

Methods:

Twenty-three phakic eyes (23 participants) with FECD (grades 1–6, modified Krachmer scale) and 8 normal eyes (8 participants) were examined by Scheimpflug photography. Central corneal thickness, high-order aberrations from anterior and posterior corneal surfaces, and backscatter from the anterior, mid-, and posterior cornea were determined from the Scheimpflug images. A low-oxygen permeable contact lens was placed on the eye, and eyes were closed for 2 hours, after which the lens was removed and Scheimpflug photography was repeated for up to 5 hours to determine changes in backscatter and high-order aberrations.

Results:

Corneas swelled by 10% [95% confidence interval (CI), 9–10]. Backscatter from the anterior cornea increased by 416 scatter units (SU, 95% CI, 344–488; P < 0.001), independent of the presence and severity of FECD. Recovery of anterior backscatter was slower in advanced FECD (81 SU/h, 95% CI, 60–120) compared with normal (123 SU/h, 95% CI, 95–150; P = 0.019). Anterior and posterior corneal high-order aberrations, and mid and posterior backscatter, did not increase with induced swelling.

Conclusions:

Inducing corneal edema increases anterior corneal backscatter but not high-order aberrations. Subjective poor vision in the morning in FECD is probably caused by scattered light rather than by high-order aberrations, suggesting that these patients experience more disability glare than decreased visual acuity.
Prevalence of Meibomian Gland Atrophy in a Pediatric Population
Authors: Gupta Preeya K. , Stevens Madelyn N. , Kashyap Namita , Priestley Yos
Published: December 2017

Purpose:

To report the prevalence of meibomian gland atrophy and gland tortuosity in a pediatric population.

Methods:

Participants who presented with no history of dry eye disease or meibomian gland dysfunction were recruited from the Duke University Eye Center. Meibography was performed and subjective symptoms were assessed through the Standard Patient Evaluation of Eye Dryness (SPEED) questionnaire. Grading of images was assessed by a masked rater using a previously validated 5-point meiboscale (0–4) for gland atrophy and a 3-point scale for gland tortuosity (0–2).

Results:

Ninety-nine eyes of 99 participants (50 females) aged 4 to 17 years (mean 9.6 years) were imaged. The mean meiboscore was 0.58 ± 0.80 (mean ± SD) for gland atrophy and 0.45 ± 0.64 for tortuosity. In all subjects, 42% (n = 42) had any evidence of meibomian gland atrophy (meiboscore >0) and 37% (n = 37) had any evidence of meibomian gland tortuosity. The majority of subjects had mild gland atrophy. No significant association was found between age, sex, or race and presence of gland atrophy. Males were significantly more likely to have gland tortuosity (P = 0.0124, odds ratio 3.36).

Conclusions:

This study reveals a relatively high level of mild meibomian gland atrophy in the pediatric population, though moderate-severe gland atrophy was also present in this young population. This calls into question our current understanding of baseline gland architecture and suggests that perhaps clinicians should be examining young patients for meibomian gland atrophy and dysfunction because it may have implications for future development of dry eye disease.
The Effect of Pancreatic Juice Collection Time on the Detection of KRAS Mutations
Authors: Suenaga Masaya , Dudley Beth , Karloski Eve , Borges Michael , Irene Canto Marcia , Brand Randall E. , Goggins Michael
Published: December 2017

Objective

Secretin-stimulated pancreatic juice is collected from the duodenum and analyzed to identify biomarkers of pancreatic neoplasia, but the optimal duration of pancreatic juice collection is not known.

Methods

We compared the yield of KRAS mutations detected in pancreatic juice samples aspirated from near the duodenal papilla at 1 to 5, 6 to 10, and 11 to 15 minutes after secretin infusion, and from the third part of the duodenum (at 15 minutes) from 45 patients undergoing endoscopic ultrasound pancreatic surveillance. KRAS mutation concentrations were measured by using droplet digital polymerase chain reaction.

Results

Forty of 45 patients had KRAS mutations detected in their pancreatic juice, and most patients' juice samples had more than 1 KRAS mutation. Of 106 KRAS mutations detected in 171 pancreatic juice samples, 58 were detected in the 5-minute samples, 70 mutations were detected in the 10-minute samples, and 65 were detected in the 15-minute samples. Nine patients who did not have KRAS mutations detected in their 5-minute sample had mutations detected in samples collected at later time points. Ninety-percent of all pancreatic juice mutations detected in any sample were detected in the 5- or 10-minute samples.

Conclusions

Collecting pancreatic juice for 10 minutes after secretin infusion increases the likelihood of detecting pancreatic juice mutations over shorter collections.
Health Literacy and Health Status in People With Chronic Heart Failure
Authors: Como June M.
Published: December 2017

Purpose/Aim:

The aim of this study was to investigate whether health literacy, self-efficacy, and medication adherence can explain or predict the variance in health outcomes (measured as perceived physical or mental health status [HS]) in persons with chronic heart failure (HF).

Design:

A nonexperimental cross-sectional survey study used data gathered from 175 patients with chronic HF from urban cardiology practices in the northeast United States.

Methods:

The Paasche-Orlow and Wolf Causal Pathways conceptual model and Bandura's self-efficacy theory were used to select and test variables in the study. A demographic questionnaire, the Short Test of Functional Health Literacy, the Self-Efficacy for Appropriate Medication Use Scale, the Morisky Medication Adherence Scale, and the Short Form-12 version 2 assessing perceived physical and mental HS were completed. Multiple hierarchical regression analyses were used to analyze relationships among the variables.

Results:

Significant associations between health literacy and self-efficacy and between health literacy and perceived mental HS were found (P < .05). High self-efficacy was the strongest predictor of physical HS (P < .01). The strongest predictor of mental HS was medication adherence (P < .01).

Conclusions:

Support of self-efficacy and medication adherence may improve HS. Including health literacy strategies in clinical practice may support improvements in HS in people with chronic HF.
A prediction model of working memory across health and psychiatric disease using whole-brain functional connectivity
Authors: Yamashita Masahiro , Yoshihara Yujiro , Hashimoto Ryuichiro , Yahata Noriaki , Ichikawa Naho , Sakai Yuki , Yamada Takashi , Matsukawa Noriko , Okada Go , Tanaka Saori C. , Kasai Kiyoto , Kato Nobumasa , Okamoto Yasumasma , Seymour Ben , Takahashi Hidehiko , Kawato Mitsuo , Imamizu Hiroshi
Published: December 2017

Individual differences in cognitive function have been shown to correlate with brain-wide functional connectivity, suggesting a common foundation relating connectivity to cognitive function across healthy populations. However, it remains unknown whether this relationship is preserved in cognitive deficits seen in a range of psychiatric disorders. Using machine learning methods, we built a prediction model of working memory function from whole-brain functional connectivity among a healthy population (N = 17, age 19-24 years). We applied this normative model to a series of independently collected resting state functional connectivity datasets (N = 968), involving multiple psychiatric diagnoses, sites, ages (18-65 years), and ethnicities. We found that predicted working memory ability was correlated with actually measured working memory performance in both schizophrenia patients (partial correlation, ρ = 0.25, P = 0.033, N = 58) and a healthy population (partial correlation, ρ = 0.11, P = 0.0072, N = 474). Moreover, the model predicted diagnosis-specific severity of working memory impairments in schizophrenia (N = 58, with 60 controls), major depressive disorder (N = 77, with 63 controls), obsessive-compulsive disorder (N = 46, with 50 controls), and autism spectrum disorder (N = 69, with 71 controls) with effect sizes g = −0.68, −0.29, −0.19, and 0.09, respectively. According to the model, each diagnosis’s working memory impairment resulted from the accumulation of distinct functional connectivity differences that characterizes each diagnosis, including both diagnosis-specific and diagnosis-invariant functional connectivity differences. Severe working memory impairment in schizophrenia was related not only with fronto-parietal, but also widespread network changes. Autism spectrum disorder showed greater negative connectivity that related to improved working memory function, suggesting that some non-normative functional connections can be behaviorally advantageous. Our results suggest that the relationship between brain connectivity and working memory function in healthy populations can be generalized across multiple psychiatric diagnoses. This approach may shed new light on behavioral variances in psychiatric disease and suggests that whole-brain functional connectivity can provide an individual quantitative behavioral profile in a range of psychiatric disorders.
Neuronal glutamate transporters control dopaminergic signaling and compulsive behaviors
Authors: Bellini Stefania , Fleming Kelsey E. , De Modhurika , McCauley John P. , Petroccione Maurice A. , D’Brant Lianna Y. , kachenko Artem , Kwon SoYoung , Jones Lindsey A. , Scimemi Annalisa
Published: December 2017

There is an ongoing debate on the contribution of the neuronal glutamate transporter EAAC1 to the onset of compulsive behaviors. Here we use behavioral, electrophysiological, molecular and viral approaches in male and female mice to identify the molecular and cellular mechanisms by which EAAC1 controls the execution of repeated motor behaviors. Our findings show that in the striatum, a brain region implicated with movement execution, EAAC1 limits group I metabotropic glutamate receptor (mGluRI) activation, facilitates D1 dopamine receptor (D1R) expression and ensures long-term synaptic plasticity. Blocking mGluRI in slices from mice lacking EAAC1 restores D1R expression and synaptic plasticity. Conversely, activation of intracellular signaling pathways coupled to mGluRI in D1R-expressing striatal neurons of mice expressing EAAC1 leads to reduced D1R expression and increased stereotyped movement execution. These findings identify new molecular mechanisms by which EAAC1 can shape glutamatergic and dopaminergic signals and control repeated movement execution.

SIGNIFICANCE STATEMENT

Genetic studies implicate Slc1a1, a gene encoding the neuronal glutamate transporter EAAC1, with obsessive-compulsive disorder (OCD). EAAC1 is abundantly expressed in the striatum, a brain region that is hyperactive in OCD. What remains unknown is how EAAC1 shapes synaptic function in the striatum. Our findings show that EAAC1 limits activation of metabotropic glutamate receptors (mGluRI) in the striatum and, by doing so, it promotes D1R expression. Targeted activation of signaling cascades coupled to mGluRI in mice expressing EAAC1 reduces D1R expression and triggers repeated motor behaviors in mice. These findings provide new information on the molecular basis of OCD and suggest new avenues for its treatment.
Subthalamic Nucleus Neurons Differentially Encode Early and Late Aspects of Speech Production
Authors: Lipski WJ , Alhourani A , Pirnia T , Jones PW , Dastolfo-Hromack C , Helou LB , Crammond DJ , Shaiman S , Dickey MW , Holt LL , Turner RS , Fiez JA , Richardson RM
Published: December 2017

Basal ganglia-thalamocortical loops mediate all motor behavior, yet little detail is known about the role of basal ganglia nuclei in speech production. Using intracranial recording during deep brain stimulation surgery, we tested the hypothesis that the firing rate of subthalamic nucleus neurons is modulated in response to both planning and motor execution aspects of speech. Nearly half of 79 recorded units exhibited firing rate modulation, during a syllable reading task administered in 12 subjects. Trial-to-trial timing of changes in subthalamic neuronal activity, relative to cue onset versus production onset, revealed that locking to cue presentation was associated more with units that decreased firing rate, while locking to speech onset was associated more with units that increased firing rate. These uniquely acquired data indicate that subthalamic activity is dynamic during the production of speech, reflecting temporally-dependent inhibition and excitation of separate populations of subthalamic neurons.
GrandPrix: Scaling up the Bayesian GPLVM for single-cell data
Authors: Ahmed Sumon , Rattray Magnus , Boukouvalas Alexis
Published: December 2017

Motivation

The Gaussian Process Latent Variable Model (GPLVM) is a popular approach for dimensionality reduction of single-cell data and has been used for pseudotime estimation with capture time information. However current implementations are computationally intensive and will not scale up to modern droplet-based single-cell datasets which routinely profile many tens of thousands of cells.

Results

We provide an efficient implementation which allows scaling up this approach to modern single-cell datasets. We also generalize the application of pseudotime inference to cases where there are other sources of variation, such as branching dynamics. We apply our method on microarray, nCounter, RNA-seq, qPCR and droplet-based datasets from different organisms. The model converges an order of magnitude faster compared to existing methods whilst achieving similar levels of estimation accuracy. Further, we demonstrate the flexibility of our approach by extending the model to higher-dimensional latent spaces that can be used to simultaneously infer pseudotime and other structure such as branching. Thus, the model has the capability of producing meaningful biological insights about cell ordering as well as cell fate regulation.

Availability

Software available at github.com/ManchesterBioinference/GrandPrix.
Metabolic traits predict the effects of warming on phytoplankton competition
Authors: Bestion Elvire , Garcia-Carreras Bernardo , Schaum Charlotte-Elisa , Pawar Samraat , Yvon-Durocher Gabriel
Published: December 2017

Understanding how changes in temperature affect interspecific competition is critical for predicting changes in ecological communities as the climate warms. Here we develop a simple theoretical model that links interspecific differences in metabolic traits, which capture the temperature-dependence of resource acquisition, to the outcome of pairwise competition in phytoplankton. We parameterised our model with metabolic traits derived from six species of freshwater phytoplankton and tested its ability to predict the outcome of competition in all pairwise combinations of the species in a factorial experiment, manipulating temperature and nutrient availability. The model correctly predicted the outcome of competition in 71% of the pairwise experiments. These results demonstrate that metabolic traits play a key role in determining how changes in temperature influence interspecific competition and lay the foundation for developing theory to predict the effects of warming in complex, multi-species communities.
Drosophila have distinct activity-gated pathways that mediate attraction and aversion to CO2
Authors: van Breugel Floris , Huda Ainul , Dickinson Michael H.
Published: December 2017

Carbon dioxide is a volatile and broad signal of many organic processes, and serves as a convenient cue for insects in search of blood hosts1–6, flowers7, decaying matter8–11, communal nests12, fruit13, and wildfires14. Curiously, although Drosophila melanogaster feed on yeast that produce CO2 and ethanol during fermentation, laboratory experiments suggest that flies actively avoid CO215–25. Here, we resolve this paradox by showing that both flying and walking fruit flies do actually find CO2 attractive, but only when they are in an active state associated with foraging. Aversion at low activity levels may be an adaptation to avoid CO2-seeking-parasites, or succumbing to respiratory acidosis in the presence of high concentrations of CO2 that are occasionally found in nature26,27. In contrast to CO2, flies are attracted to ethanol in all behavioral states, and invest twice as much time searching near ethanol compared to CO2. These behavioral differences reflect the fact that whereas CO2 is a generated by many natural processes, ethanol is a unique signature of yeast fermentation. Using genetic tools, we determined that the evolutionarily ancient ionotropic co-receptor IR25a is required for both CO2 and ethanol attraction, and that the receptors previously identified for CO2 avoidance are not involved. Our study lays the foundation for future research to determine the neural circuits underlying both state- and odorant-dependent decision making in Drosophila.
Subject-independent decoding of affective states using functional near-infrared spectroscopy
Authors: Trambaiolli Lucas R. , Tossato Juliana , Cravo André M. , Biazoli Claudinei E. , Sato João R.
Published: December 2017

Affective decoding is the inference of human emotional states using brain signal measurements. This approach is crucial to develop new therapeutic approaches for psychiatric rehabilitation, such as affective neurofeedback protocols. To reduce the training duration and optimize the clinical outputs, an ideal clinical neurofeedback could be trained using data from an independent group of volunteers before being used by new patients. Here, we investigated if this subject-independent design of affective decoding can be achieved using functional near-infrared spectroscopy (fNIRS) signals from frontal and occipital areas. For this purpose, a linear discriminant analysis classifier was first trained in a dataset (49 participants, 24.65±3.23 years) and then tested in a completely independent one (20 participants, 24.00±3.92 years). Significant balanced accuracies between classes were found for positive vs. negative (64.50 ± 12.03%, p<0.01) and negative vs. neutral (68.25 ± 12.97%, p<0.01) affective states discrimination during a reactive block consisting in viewing affective-loaded images. For an active block, in which volunteers were instructed to recollect personal affective experiences, significant accuracy was found for positive vs. neutral affect classification (71.25 ± 18.02%, p<0.01). In this last case, only three fNIRS channels were enough to discriminate between neutral and positive affective states. Although more research is needed, for example focusing on better combinations of features and classifiers, our results highlight fNIRS as a possible technique for subject-independent affective decoding, reaching significant classification accuracies of emotional states using only a few but biologically relevant features.
Quantitative Imaging of Receptor-Ligand Engagement in Intact Live Animals
Authors: Rudkouskaya Alena , Sinsuebphon Nattawut , Ward Jamie , Tubbesing Kate , Intes Xavier , Barroso Margarida
Published: December 2017

Maintaining an intact tumor environment is critical for quantitation of receptor-ligand engagement in a targeted drug development pipeline. However, measuring receptor-ligand engagement in vivo and non-invasively in preclinical settings is extremely challenging. We found that quantitation of intracellular receptor-ligand binding can be achieved using whole-body macroscopic lifetime-based Förster Resonance Energy Transfer (FRET) imaging in intact, live animals bearing tumor xenografts. We determined that FRET levels report on ligand binding to transferrin receptors conversely to raw fluorescence intensity. We then established that FRET levels in heterogeneous tumors correlate with intracellular ligand binding but strikingly, not with ubiquitously used ex vivo receptor expression assessment. Hence, MFLI-FRET provides a direct measurement of systemic delivery, target availability and intracellular drug delivery in intact animals. Here, we have used MFLI to measure FRET longitudinally in intact animals for the first time. MFLI-FRET is well–suited for guiding the development of targeted drug therapy in heterogeneous intact, live small animals.
Unsupervised correction of gene-independent cell responses to CRISPR-Cas9 targeting
Authors: Iorio Francesco , Behan Fiona M , Gonçalves Emanuel , Bhosle Shriram G , Chen Elisabeth , Shepherd Rebecca , Beaver Charlotte , Ansari Rizwan , Pooley Rachel , Wilkinson Piers , Harper Sarah , Butler Adam P , Stronach Euan A , Saez-Rodriguez Julio , Yusa Kosuke , Garnett Mathew J
Published: December 2017

Background:Genome editing by CRISPR-Cas9 technology allows large-scale screening of gene essentiality in cancer. A confounding factor when interpreting CRISPR-Cas9 screens is the high false-positive rate in detecting essential genes within copy number amplified regions of the genome. We have developed the computational toolCRISPRcleanRwhich is capable of identifying and correcting gene-independent responses to CRISPR-Cas9 targeting. CRISPRcleanR uses an unsupervised approach based on the segmentation of single-guide RNA fold change values across the genome, without making any assumption about the copy number status of the targeted genes.

ResultsApplying our method to existing and newly generated genome-wide essentiality profiles from 15 cancer cell lines, we demonstrate that CRISPRcleanR reduces false positives when calling essential genes, correcting biases within and outside of amplified regions, while maintaining true positive rates. Established cancer dependencies and essentiality signals of amplified cancer driver genes are detectable post-correction. CRISPRcleanR reports sgRNA fold changes and normalised read counts, is therefore compatible with downstream analysis tools, and works with multiple sgRNA libraries.

ConclusionsCRISPRcleanR is a versatile open-source tool for the analysis of CRISPR-Cas9 knockout screens to identify essential genes.
Nestin in immature embryonic neurons regulates axon growth cone morphology and Semaphorin3a sensitivity
Authors: Bott C.J. , Johnson C. G. , Yap C.C. , Dwyer N.D. , Litwa K.A. , Winckler B.
Published: December 2017

Correct wiring in the neocortex requires that responses to an individual guidance cue vary among neurons in the same location, and within the same neuron over time. Nestin is an atypical intermediate filament expressed highly in neural progenitors and is thus used widely as a progenitor marker. Here we show a subpopulation of embryonic cortical neurons which transiently express nestin in their axons. Nestin expression is thus not restricted to neural progenitors but persists at lower levels in some newborn neurons for 2-3 days. We found that nestin-expressing neurons have smaller growth cones, suggesting that nestin affects cytoskeletal dynamics. Nestin, unlike other intermediate filament subtypes, regulates cdk5 kinase. Cdk5 activity is induced by the repulsive guidance cue Sema3a leading to growth cone collapse in vitro. Therefore, we tested whether nestin-expressing neurons showed altered responses to Sema3a. We find that nestin-expressing newborn neurons are more sensitive to Sema3a in a roscovitine-sensitive manner, whereas nestin knockdown results in lowered sensitivity to Sema3a. We propose that nestin functions in immature neurons to modulate cdk5 and thereby the Sema3a response. Thus, the transient expression of nestin could allow for temporal modulation of a neuron's response to Sema3a particularly during early axon guidance decisions.
Glucose facilitates Aβ oligomerization and tau phosphorylation in C. elegans model of Alzheimer’s disease
Authors: Ahmad Waqar
Published: December 2017

Formation of Aβ plaques from peptide oligomers and development of neurofibrillary tangles from hyperphosphorylated tau are hallmarks of Alzheimer’s disease (AD). These markers of AD severity are further associated with impaired glucose metabolism. However, the exact role of glucose metabolism on disease progression has not been elucidated. In this study, the effects of glucose on Aβ and tau-mediated toxicity are investigated using a C. elegans model system. We find that addition of glucose or 2-deoxy-d-glucose (2DOG) to the growth medium delayed Aβ-associated paralysis, though it was unable to restore previously impaired acetylcholine neurotransmission in pre-existing Aβ-mediated pathology. Glucose also inhibited egg laying and hatching in the worms that express Aβ. The harmful effects of glucose were associated with an increase in toxic Aβ oligomers. Increased phosphorylation of tau is associated with formation of neurofibrillary tangles (NFTs) and increased severity of AD, but O-β-GlcNAcylation can inhibit phosphorylation of adjacent phosphorylation sites. We reasoned that high glucose levels might induce tau O-β-GlcNAcylation, thereby protecting against tau phosphorylation. Contrary to our expectation, glucose increased tau phosphorylation but not O-β-GlcNAcylation. Increasing O-β-GlcNAcylation, either with Thiamet-G (TMG) or by suppressing the O-GlcNAcase (oga-1) gene does interfere with and therefore reduce tau phosphorylation. Furthermore, reducing O-β-GlcNAcylation by suppressing O-GlcNAc transferase (ogt-1) gene causes an increase in tau phosphorylation. These results suggest that protective O-β-GlcNAcylation is not induced by glucose. Instead, as with vertebrates, we demonstrate that high levels of glucose exacerbate disease progression by promoting Aβ aggregation and tau hyperphosphorylation, resulting in disease symptoms of increased severity. The effects of glucose cannot be effectively managed by manipulating O-β-GlcNAcylation in the tau models of AD in C. elegans. Our observations suggest that glucose enrichment is unlikely to be an appropriate therapy to minimize AD progression.
The role of peripherality in students’ entrepreneurial learning
Authors: Kubberød Elin , Pettersen Inger Beate
Published: December 2017

Purpose

The purpose of this paper is to expand on the entrepreneurial learning literature and situated learning theory to explore how students with different educational backgrounds learn to recognise opportunities at the periphery of an entrepreneurial practice. The authors theoretically outline factors that may influence students’ entrepreneurial learning, including co-participation and roles at the periphery, power relations in communities of practice (CoP), and emotional exposure. The authors make use of the concept legitimate peripheral participation and Politis’ entrepreneurial learning framework to explore empirically students’ entrepreneurial learning transformations and entrepreneurial learning outcomes.

Design/methodology/approach

The authors adopted a qualitative approach in research, used the focus group methodology and the critical incident technique in interviewing. The research investigated two groups of Norwegian master students that differed in educational background aiming to explore their experience with entrepreneurial learning in a three months long internship in American start-ups representing emerging CoPs.

Findings

The research identified important factors influencing students’ entry transitions into an entrepreneurial practice, highlighting the complexity in peripheral participation. By acknowledging and exploring the social dimensions in students’ learning, the authors demonstrate and exemplify how these influence students’ entrepreneurial learning trajectories, learning outcomes and ultimately their influence in students’ contributions to the practice community.

Originality/value

The research integrates the existing entrepreneurial learning literature and situated learning theory to identify various factors influencing entrepreneurial learning, contributing with novel insights about the role of peripherality in students’ entrepreneurial learning in situated practice.
Information seeking by geoscientists: an update on Bichteler and Ward (1989)
Authors: Alstad Knut , Hertzum Morten
Published: December 2017

Purpose

The purpose of this paper is to investigate how often geoscientists use different information sources and how this pattern of source use balances their perceptions of the quality and ease of use of the information sources.

Design/methodology/approach

The geoscientists at the Geological Survey of Norway were surveyed about their information-seeking behavior. The response rate was 70 percent.

Findings

The geoscientists primarily relied on web search and colleagues for information. These two information sources were perceived as easy to use, more so than bibliographic databases (GeoRef, Web of Science, and the library database). Bibliographic databases were used infrequently and perceived as yielding poorer quality results than consulting a colleague. The likelihood of using web search and colleagues to find information about a new topic was determined by the ease of using these sources. In contrast, the quality of the resulting information did not determine the frequency with which any of the information sources were used. The geoscientists who spent more time looking for information searched the web more often, had more reservations toward the quality of information obtained from colleagues, and read more journal articles and conference papers.

Research limitations/implications

Geoscientists’ use of an information source is self-reinforcing and unlikely to increase through improving its quality alone. It should be noted that the study is restricted to one geoscience organization.

Originality/value

The main reference about the information-seeking behavior of geoscientists is almost three decades old. This study provides an update.
Multinational enterprises, risk management, and the business and economics of peace
Authors: Oetzel Jennifer , Miklian Jason
Published: December 2017

Purpose

The purpose of this paper is to reconceptualize how managers of multinational enterprises (MNEs) manage risk, particularly in fragile and/or conflict-affected areas of operation. The authors suggest that MNEs consider reducing risk at its source rather than trying to avoid or react to risks as they occur. By incorporating peacebuilding strategies, managers may not only reduce investment risk but also contribute to stability and prosperity in the communities where they operate, and gain a competitive advantage in doing so.

Design/methodology/approach

The authors show how firms can take a more holistic approach to working in conflict-affected areas. They do so by overlaying conceptualizations of risk with those of peacebuilding and then use case examples to illustrate how such actions work in practice.

Findings

Using a series of examples, the authors find that MNEs that incorporate peacebuilding frameworks in their risk calculations in complex settings tend to have a better understanding of local environments and how they affect firm operations and profitability. These same MNEs may hold a long-term advantage over international competitors that do not share the same understanding.

Originality/value

The authors argue that the study of relationships between international businesses and society in conflict-affected or fragile areas of operation is under-developed and tends to focus on negative (risk-aversion) aspects as opposed to positive (value-added) opportunities. This paper offers new ways in which these relationships can be reconceptualized. The authors’ main takeaway is that a peacebuilding approach does not require corporations to be arbitrators of peace at the expense of profit. Rather, it is instead a broader way to conceptualize and weigh risk when working in the world’s most challenging regions. This approach is more likely to be in the long-term interest of both the firm and the local society where the firm operates.
Influencing Fairtrade consumption through servant leadership: Bruce Crowther’s story
Authors: Samuel Anthony , White Gareth R.T. , Martin Helen , Rowling Martyn
Published: December 2017

Purpose

This study aims to expand understanding of servant leadership beyond organisational boundaries by making an examination of its role in the establishment and growth of a social movement.

Design/methodology/approach

This paper’s findings are developed from four sequential, semi-structured interviews and a narrated tour of Garstang with the founder of the Fairtrade Towns (FTT) movement. It follows a theoretical framework of servant leadership (SLship) from Spears (1996; 2009). Evidence is gathered through in-depth investigation of the activities of Bruce Crowther, the architect and driving force behind the FTT initiative.

Findings

The findings discovered how SLship operates in a social, place-based setting to influence Fairtrade consumption. The paper argues the success of the FTT movement is linked to Bruce Crowther’s leadership. The findings presented draw and expand upon Spears’ ten characteristics of SLship. Utilisation of this framework sees Crowther emerge as a servant leader operating at a community level to influence FT consumption via the FTT movement.

Originality/value

The paper makes a contribution to theory by identifying the novel characteristic of servant leaders that is exploring affinity and proffers it as an extension of Spears’ framework. It also provides valuable information about the impact and importance of SLship in the efficacious advance of ethical consumerism.
Structural Integrity Analysis of Gas–Liquid Cylindrical Cyclone (GLCC) Separator Inlet
Authors: Swaroop Kolla Srinivas , Mohan Ram S. , Shoham Ovadia
Published: December 2017

The gas–liquid cylindrical cyclone (GLCC) is a simple, compact, and low-cost separator, which provides an economically attractive alternative to conventional gravity-based separators over a wide range of applications. Over the past 22 years, more than 6500 GLCCs have been installed around the world by the petroleum and related industries. However, to date no systematic study has been carried out on its structural integrity. The GLCC inlet section design is a key parameter, which is crucial for its performance and proper operation. This paper presents finite element analysis simulation results aimed at investigating the effect of various parameters on the inlet section structural integrity. Finally, recommendations on design modifications are presented, directed at strengthening the inlet section.
Effect of Intake Charge Preheating and Equivalence Ratio in a Dual Fuel Diesel Engine Run on Biogas and Ethanol-Blended Diesel
Authors: Sarkar Achinta , Saha Ujjwal K.
Published: December 2017

Dual fuel diesel (DFD) engines have been gaining popularity due to the flexibility of using both bio and fossil liquid and gaseous fuels. Further, the efficient combustion in DFD mode with bio liquid and gaseous fuel can greatly reduce the greenhouse gas emissions as well as the dependency on fossil diesel. In recent times, a host of investigation has been done in normal dual fuel diesel (nDFD) mode with pure diesel and biogas. However, the engines with ethanol blended with diesel and intake charge (biogas–air mixture) with preheating have not been studied. In the present study, 5% ethanol blended with diesel (E5) and biogas with preheating are used in dual fuel engine (DFD-E5) to find their performance and emission characteristics. In order to have a direct comparison of performances, an engine with pure diesel (E0) and biogas with preheating is also tested in dual fuel mode (DFD-E0). In all the cases, the effect of total equivalence ratio on engine overall performance has also been investigated. In DFD-E5 mode, and at the maximum torque of 21.78 N·m, the brake thermal efficiency (BTE) increases by 2.98% as compared to nDFD mode. At the same torque, there is no trace of carbon monoxide (CO), whereas there is a reduction of hydrocarbon (HC) emission by 62.22% with respect to pure diesel (PD) mode. The nitrogen of oxides (NOx) is found to decrease in DFD modes in contrast to PD mode.
Simulation Study of a Digital Hydraulic Drive for a Knee Joint Exoskeleton
Authors: Holl Eva , Scheidl Rudolf , Eshkabilov Sulaymon
Published: December 2017

Even though the majority of currently published exoskeletons prototypes employ electrical drives, great opportunities are seen for hydraulic drives. Their main advantages are the unrivalled force and power density, facilitating the low additional masses at the peripheral limb joints, and the simple realization of locking, damping, and recuperation functions. The latter function is feasible with some hydraulic control concepts, like primary or secondary motion control. In this paper a digital cylinder drive is studied for getting up from a crouch. This motion is a sound benchmark to test the ability of the drive for exoskeleton knee joint actuation. Digital cylinders can realize output torques only in steps and the transition between different steps can create jerky motions. In this study the motion quality and the losses are evaluated for a binary stepped digital cylinder with four different chambers.
Experimental Validation of Flow Force Models for Fast Switching Valves
Authors: Bender Niels C. , Noergaard Christian , Pedersen Henrik C.
Published: December 2017

This paper comprises a detailed study of the forces acting on a Fast Switching Valve (FSV) plunger. The objective is to investigate to what extend different models are valid to be used for design purposes. These models depend on the geometry of the moving plunger and the properties of the surrounding medium. A few analytic expressions have been suggested in the literature and these have been supported by CFD simulations, yielding accurate coherence for a large part of the fluid domain. However, when a moving body approaches a stationary body, squeeze film effects will occur if the plunger velocity is non-zero. This is the case in FSVs, where it results in an additional dampening effect, which is of relevance when analyzing contact-impact. Experimental data from different tests cases of a FSV has been gathered, with the plunger moving through a medium of either oil or air. This data is used to compare and validate different models, where an effort is directed towards capturing the fluid squeeze effect just before material on material contact. The test data is compared with simulation data relying solely on analytic formulations. The general dynamics of the plunger is validated for the established models, but an additional investigation of the dampening force is necessary. Therefore, numerical analyses are introduced to enhance the knowledge of the hydrodynamic end dampening. This has a visible effect on the velocity profile at the end-stop. This profile represents the measurements more accurately, but it is not possible to verify the velocity profile at the valve seat end-stop due to measurement uncertainties.
Kinematic Multi-Objective Optimization of Circular-Toothed Gerotor Pumps by Genetic Algorithm
Authors: Robison Andrew J. , Vacca Andrea
Published: December 2017

A gerotor gear generation algorithm has been developed that evaluates key performance objective functions to be minimized or maximized, and then an optimization algorithm is applied to determine the best design. Because of their popularity, circular-toothed gerotors are the focus of this study, and future work can extend this procedure to other gear forms. Parametric equations defining the circular-toothed gear set have been derived and implemented. Two objective functions were used in this kinematic optimization: maximize the ratio of displacement to pump radius, which is a measure of compactness, and minimize the kinematic flow ripple, which can have a negative effect on system dynamics and could be a major source of noise. Designs were constrained to ensure drivability, so the need for additional synchronization gearing is eliminated. The NSGA-II genetic algorithm was then applied to the gear generation algorithm in modeFRONTIER, a commercial software that integrates multi-objective optimization with third-party engineering software. A clear Pareto front was identified, and a multi-criteria decision-making genetic algorithm was used to select three optimal designs with varying priorities of compactness vs low flow variation. In addition, three pumps used in industry were scaled and evaluated with the gear generation algorithm for comparison. The scaled industry pumps were all close to the Pareto curve, but the optimized designs offer a slight kinematic advantage, which demonstrates the usefulness of the proposed gerotor design method.
Hydraulic Damper Concept for Thruster Ice Impact Load Reduction
Authors: Siivonen Lauri , Huhtala Kalevi
Published: December 2017

Steerable thrusters are used to maneuver a vessel in open sea environment. The harsh environment of arctic seas introduces certain challenges with propellers hitting ice and decreasing lifetime of the system, as the loads generated by ice impacts are significantly higher than nominal loads. Damping of an ice impact load is a difficult task since the impacts have high torsional loads and they occur only in a fraction of the lifetime of the system. Commercial dampers are hard to find since they do not generally have the capacity for damping such high loads. The proposed active hydraulic damper reduces ice impact loads by accelerating and decelerating the shaft line. The lack of space and commercial components narrow down the possibilities but simulation results with the system show some positive effects in typical ice impact scenario. The system also recuperates most of the used energy and stores it to accumulator.
Pressure Control of the Proportional Directional Control Valve Test Rig Based on the Fuzzy Proportional-Integral-Double-Integral Controller
Authors: Shi Wenzhuo , Wei Jianhua , Fang Jinhui , Li Mingjie , Zhang Qiang , Qiao Xining
Published: December 2017

The pressure drop needs to be kept constant in the flow rate/input signal performance test of proportional directional control (PDC) valve. In general, the control of valve pressure drop is implemented by regulating the relief valve or flow control valve that located between port A and port B of the PDC valve. But in this study, the load of the test valve is fixed and the stable pressure drop is obtained by changing the proportional relief valve which is placed in the inlet of the PDC valve. Then the mathematical model of the test rig and several controllers are established based on this idea. To be specific, proportional-integral (P-I) controller, proportional-integral-double-integral (P-I-II) controller, and fuzzy proportional-integral-double-integral (FP-I-II) controller are all applied to stabilize the pressure drop in this study. And the FP-I-II controller with compensation (FP-I-II-WC) is proved to be the best for this work both in the simulation and the actual experiment.
Design Optimization of Moving Magnet Actuated Valves for Digital Displacement Machines
Authors: Madsen Esben L. , Jørgensen Janus M. T. , Nørgård Christian , Bech Michael Møller
Published: December 2017

High-efficiency hydraulic machines using digital valves are presently a topic of great focus. Digital valve performance with respect to pressure loss, closing time as well as electrical power consumption, is key to obtaining high efficiency. A recent digital seat valve design developed at Aalborg University utilizing moving coil actuation, meets these performance demands but is challenged by practical issues. This paper builds upon that design by proposing a retrofit which preserves both the seat valve topology and the outer dimensions, but utilizes moving magnet actuation. Through constrained multi-objective optimization, six initial topologies and three derived topologies, including designs with one, two and four coils, are optimized with respect to overall efficiency. Apart from the actuator, the flow forces on the seat valve geometry is modeled using CFD and included in optimization. In simulation the final optimized design closes in 2.1 ms, has a pressure drop of 0.8 bar at 150 l/min and yields a digital displacement machine average chamber efficiency of 98.9%. The design is simple in construction and uses a single coil, positioned outside the pressure chamber, eliminating the need for an electrical interface to the pressurized valve chamber.