bluuebunny/crossref_metadata_2025 huggingface dataset:
Isolated Lambdoid Craniosynostosis
Authors: Borad Vedant , Cordes Emma J. , Liljeberg Katie M. , Sylvanus Tonye S. , Lim Paul K. , Wood Robert J.
Published: October 2019

Introduction:

Lambdoid craniosynostosis is an extremely rare anomaly in which there is premature fusion of one or both lambdoid sutures. The mainstay of treatment is surgical intervention, for which various procedures have been described, but there is a paucity of data on long-term outcomes. This study examines the long-term outcomes in the surgical management of this challenging condition, showing that accurate diagnosis and careful planning can lead to safe and consistent results.

Materials and Methods:

A retrospective chart review was performed looking at all cases of isolated lambdoid craniosynostosis treated with surgical intervention by the senior author from 1999 to 2016. Data collected included gender, age at diagnosis, age at surgery, length of follow up, method of diagnosis, side of affected suture, pre-operative and post-operative physical exam findings, surgical technique, complications, re-operation rate, and associated torticollis.

Results:

Twenty-five patients (N = 25) were included in the study. All patients underwent posterior calvarial remodeling with/without barrel stave osteotomies and full thickness calvarial bone grafts. Mean length of follow up after operative intervention was 43.8 months (+/− 23.2 months). All patients were judged to have significantly improved head contour which was near-normal at conversational distance during post-operative follow up by the senior author. Residual plagiocephaly was present in 24% of patients. There were no major complications in this series. Reoperation rate was 8%. Seventy-six percent of patients also presented with torticollis, of which 37% had refractory torticollis that required sternocleidomastoid (SCM) release by the senior author.

Discussion:

The authors present one of the largest series of operative cases of isolated lambdoid craniosynostosis to date. Our data show that with accurate diagnosis and careful planning, safe and consistent long-term results can be achieved with surgical intervention. A significant number of patients in our series also presented with concomitant torticollis. The authors recommend that all patients being evaluated for posterior plagiocephaly should also be evaluated for torticollis, because without recognition and intervention, patients may continue to have residual facial asymmetry and head shape abnormalities despite optimal surgical correction of the lambdoid synostosis.
The “Off-Hour Effect” in Urgent Laparoscopic Cholecystectomy for Acute Cholecystitis
Authors: Yoshioka Ryo , Tomimaru Yoshito , Noguchi Kozo , Noura Shingo , Imamura Hiroshi , Dono Keizo
Published: October 2019

Background:

The observation that patients may have worse outcomes after urgent therapeutic interventions performed during off-hours compared with on-hours is termed the “off-hour effect.” This phenomenon has not been examined in urgent laparoscopic cholecystectomy (LC). Here we aimed to investigate the off-hour effect in urgent LC for acute cholecystitis.

Patients and Methods:

This study enrolled patients who underwent urgent LC for acute cholecystitis at our institution. On-hour LC was defined as a weekday operation starting between 9 am and 9 pm; and off-hour LC as an operation on a weekend, or starting between 9 pm and 9 am on a weekday. Patients were divided into on-hour and off-hour groups, and the operative outcomes of LC were compared between these groups.

Results:

The study included 371 patients, with 270 (72.8%) on-hour, and 101 (27.2%) off-hour operations. The 2 groups did not significantly differ in operation time, intraoperative blood loss, conversion rate to open surgery, incidence of postoperative complications, or duration of postoperative hospital stay.

Discussion:

Operative outcomes of urgent LC were comparable between the on-hour and off-hour groups, suggesting that there was no significant off-hour effect in urgent LC.
Epidemiology and Comorbidity Burden of Organ Donor Referrals in Australia: Cohort Study 2010–2015
Authors: Thomson Imogen K. , Rosales Brenda M. , Kelly Patrick J. , Wyburn Kate , Waller Karen M.J. , Hirsch Daniel , O’Leary Michael J. , Webster Angela C.
Published: October 2019

Background.

Increasing organ donation rates in Australia have been exceeded by a rise in potential donor referrals not proceeding to donate. Referral evaluation is resource-intensive. We sought to characterize organ donor referrals in New South Wales, Australia, and identify predictors of referrals not proceeding to donation.

Methods.

We performed a cohort study of NSW Organ and Tissue Donation Service logs 2010–2015, describing the prevalence and impact of comorbidities on referral outcome. Logistic regression was used to identify comorbidities influencing outcome and predict probability of donation.

Results.

Of 2977 referrals, 669 (22%) donated and 2308 (78%) did not. Despite increasing donation rates, the proportion proceeding to donate declined 2010–2015. Among referrals, the prevalence of all comorbidities except cerebrovascular disease increased and was higher among nondonors. History of cardiac disease, ≥65 years of age, chronic kidney or liver disease, malignancy, and absence of cerebrovascular disease were all significantly (P < 0.01) associated with non donation. Hypertension and diabetes did not significantly impact outcome. Predicted probability of donation varied from <1% to 54% depending on comorbidity burden of the referral.

Conclusions.

Comorbidity burden among donor referrals is increasing. The presence of particular comorbidities may significantly impact referral outcome. A better understanding of referral characteristics associated with non donation may improve the efficiency of the referral process in the context of encouraging routine referrals.
Subjective Memory Complaints Are an Important Surrogate for Objective Cognitive Performance in African Americans
Authors: Boggess M. Bailee , Barber Justin M. , Jicha Gregory A. , Caban-Holt Allison
Published: October 2019

Purpose:

Subjective memory complaints (SMCs) have been shown to be associated with lower neuropsychological test scores cross-sectionally. However, it remains unclear whether such findings hold true for African American (AA) older adults.

Methods:

Baseline visit data from the National Alzheimer’s Coordinating Center database collected from September 2005 to March 2018 were used. Generalized linear mixed models specifying binomial distributions were used to examine how neuropsychological test scores affect the likelihood of reporting SMCs.

Patients:

Inclusion criteria were participants who reported AA as their primary race, 60 to 80 years of age, were cognitively unimpaired, and had a Mini-Mental Status Examination score ≥26. A total of 1021 older AA adults without missing data met the criteria.

Results:

A total of 258 participants reported a SMC. SMCs were more likely with lower scores on measures of episodic memory and processing; however, SMCs were also more likely with higher scores on a measure of working memory. Working memory appeared to mediate reporting of SMC among participants with lower episodic memory scores.

Discussion:

These findings demonstrate that SMCs are associated with lower scores on objective neuropsychological measures among older AAs. Additional work is needed to determine whether SMCs are further associated with a risk for clinical transition to mild cognitive impairment or dementia among AA older adults.
High Prevalence of Social Cognition Disorders and Mild Cognitive Impairment Long Term After Stroke
Authors: Sensenbrenner Bénédicte , Rouaud Olivier , Graule-Petot Anny , Guillemin Sophie , Piver Ariane , Giroud Maurice , Béjot Yannick , Jacquin-Piques Agnès
Published: October 2019

Purpose:

Social cognition disorders after stroke are poorly described. Yet, rehabilitation difficulties are frequent after stroke. This study aimed to evaluate the frequency of social cognition disorders 3 years after a first-ever stroke and to assess the factors associated with this condition. The second aim was to describe all the cognitive domains altered in the same population.

Methods:

Patients who suffered from a first-ever ischemic or hemorrhagic stroke underwent clinical and neuropsychological assessment, which included the mini-Social cognition and Emotional Assessment (SEA) for evaluating social cognition.

Results:

The 43 included patients were 67±15 years old, with a median Neurological Institute of Health Stroke Scale (NIHSS) (± interquartile range) at 0±1, and a median modified Rankin Scale (± interquartile range) at 1±1. Twenty patients (46.5%) had poor results in the facial emotions subtest; this factor was associated with a low educational grade (P=0.001). Fourteen patients (34.2%) had poor results on the “faux-pas” recognition subtest; this factor was associated with nonverbal episodic memory disorders (P=0.01). Thirty four patients (79.1%) had cognitive impairment, with at least 1 cognitive domain affected.

Conclusions:

The study demonstrates the high frequency of social cognition impairment 3 years after the first-ever stroke in young patients. Doctors and nurses should be sensitized to cognitive handicap after stroke because of difficulties for rehabilitation and returning to work.
Origins of Cerebral Edema: Implications for Spaceflight-Associated Neuro-Ocular Syndrome
Authors: Galdamez Laura A. , Brunstetter Tyson J. , Lee Andrew G. , Tarver William J.
Published: October 2019

Background:

Spaceflight-associated neuro-ocular syndrome (SANS) was first described in 2011 and is associated with structural ocular changes found to occur in astronauts after long-duration missions. Despite multiple insufficient potential terrestrial models, an understanding of the etiology has yet to be described.

Evidence Acquisition:

A systematic review was conducted on literature published about the pathophysiology of cerebral edema. Databases searched include PubMed, Scopus, and the Texas Medical Center Online Library. This information was then applied to create theories on mechanisms on SANS etiology.

Results:

Cerebral edema occurs through 2 general mechanisms: redistribution of ions and water intracellularly and displacement of ions and water from the vascular compartment to the brain parenchyma. These processes occur through interconnected endocrine and inflammatory pathways and involve mediators such as cytokines, matrix metalloproteases, nitric oxide, and free radicals. The pathways ultimately lead to a violation of cellular membrane ionic gradients and blood–brain barrier degradation. By applying the principles of cerebral edema pathophysiology to the optic disc edema (ODE) see in SANS, several theories regarding its etiology can be formed. Venous stasis may lead to ODE through venous and capillary distension and leak, as well as relative hypoxia and insufficient ATP substrate delivery causing axoplasmic flow stasis and local oxidative stress.

Conclusions:

Using the pathophysiology of cerebral edema as a model, hypotheses can be inferred as to the etiology of ODE in SANS. Further studies are needed to determine the presence and contribution of local vascular stasis and resulting inflammation and oxidative stress to the pathophysiology of SANS.
On the beneficent thickness of water
Authors: Branscomb E. , Russell M. J.
Published: October 2019

In the 1930s, Lars Onsager published his famous ‘reciprocal relations’ describing free energy conversion processes. Importantly, these relations were derived on the assumption that the fluxes of the processes involved in the conversion were proportional to the forces (free energy gradients) driving them. For chemical reactions, however, this condition holds only for systems operating close to equilibrium—indeed very close; nominally requiring driving forces to be smaller than
k
B
T
. Fairly soon thereafter, however, it was quite inexplicably observed that in at least some biological conversions both the reciprocal relations and linear flux–force dependency appeared to be obeyed no matter how far from equilibrium the system was being driven. No successful explanation of how this ‘paradoxical’ behaviour could occur has emerged and it has remained a mystery. We here argue, however, that this anomalous behaviour is simply a gift of water, of its viscosity in particular; a gift, moreover, without which life almost certainly could not have emerged. And a gift whose appreciation we primarily owe to recent work by Prof. R. Dean Astumian who, as providence has kindly seen to it, was led to the relevant insights by the later work of Onsager himself.
Possible mechanisms of CO
2
reduction by H
2
via prebiotic vectorial electrochemistry
Authors: Vasiliadou Rafaela , Dimov Nikolay , Szita Nicolas , Jordan Sean F. , Lane Nick
Published: October 2019

Methanogens are putatively ancestral autotrophs that reduce CO
2
with H
2
to form biomass using a membrane-bound, proton-motive Fe(Ni)S protein called the energy-converting hydrogenase (Ech). At the origin of life, geologically sustained H
+
gradients across inorganic barriers containing Fe(Ni)S minerals could theoretically have driven CO
2
reduction by H
2
through vectorial chemistry in a similar way to Ech. pH modulation of the redox potentials of H
2
, CO
2
and Fe(Ni)S minerals could in principle enable an otherwise endergonic reaction. Here, we analyse whether vectorial electrochemistry can facilitate the reduction of CO
2
by H
2
under alkaline hydrothermal conditions using a microfluidic reactor. We present pilot data showing that steep pH gradients of approximately 5 pH units can be sustained over greater than 5 h across Fe(Ni)S barriers, with H
+
-flux across the barrier about two million-fold faster than OH
–
-flux. This high flux produces a calculated 3-pH unit-gradient (equating to 180 mV) across single approximately 25-nm Fe(Ni)S nanocrystals, which is close to that required to reduce CO
2
. However, the poor solubility of H
2
at atmospheric pressure limits CO
2
reduction by H
2
, explaining why organic synthesis has so far proved elusive in our reactor. Higher H
2
concentration will be needed in future to facilitate CO
2
reduction through prebiotic vectorial electrochemistry.
Radionuclide-induced defect sites in iron-bearing minerals may have accelerated the emergence of life
Authors: Ponce Adrian
Published: October 2019

The emergence of life on Earth (and elsewhere) must have occurred in a milieu that is far from equilibrium, such as at alkaline hydrothermal vents that would have harboured built-in gradients in temperature, redox potential and pH along with precipitated iron-bearing minerals capable of separating these gradients, concentrating reactants and catalysing requisite protobiotic reactions. Iron-bearing minerals such as mackinawite, greenalite and fougèrite have been investigated as catalysts for protobiotic reactions, including amino acid synthesis. In the field of heterogeneous catalysis, it is well known that defect sites in the crystal structure are often the most active sites for catalysis, and mineral catalysts that have been exposed to ionizing radiation are known to exhibit increased reactivity due to radiation-induced defect sites. In this work, we (i) review the literature on the radioactive environment of the Hadean era, (ii) highlight the role of radionuclide ionizing radiation from238U,232Th and40K in generating defect sites with high catalytic activity for the chemical evolution of organic molecules, and (iii) hypothesize that these processes accelerated the emergence of life.
Community gender systems and daughter’s risk of female genital mutilation/cutting: New theory and application to Egypt
Authors: Yount Kathryn M. , Cheong Yuk Fai , James-Hawkins Laurie , Grose Rose Grace , Hayford Sarah R.
Published: October 2019

We proposed and tested a feminist social-ecological theory about daughters’ experience of female genital mutilation/cutting (FGMC) in Egypt, where over 90% of women ages 15–49 are cut. FGMC has potential adverse effects on demographic and health outcomes and has been defined as a human-rights violation. Contextual factors are important determinants of FGMC, but an integrated theory is lacking, and quantitative multilevel research is limited. We theorized that more favorable community-level gender systems, including gender norms opposing FGMCandexpanded opportunities for women outside of the family, would be associated with a daughter’s lower risk of FGMC and would strengthen the negative association of a mother’s opposition to FGMC with her daughter’s risk of cutting. Using a national sample of 14,171 mother-daughter dyads from the 2014 Egypt Demographic and Health Survey, we estimated multilevel discrete-time hazard models to test these relationships. Community gender norms opposing FGMC had significant direct, negative associations with the hazard that a daughter was cut, but women’s opportunities outside the family did not. Maternal opposition to FGMC was negatively associated with cutting a daughter, and these associations were stronger where community opposition to FGMC and opportunities for women were greater. Results provided good support for a gender-systems theory of the multilevel influences on FGMC. Integrated, multilevel interventions that address gender norms about FGMC and opportunities for women in the community, as well as beliefs about the practice among the mothers of at-risk daughters may be needed for sustainable declines in the practice.
Targeting the centromedian thalamic nucleus for deep brain stimulation
Authors: Warren Aaron E.L , Dalic Linda J. , Thevathasan Wesley , Roten Annie , Bulluss Kristian J. , Archer John S.
Published: October 2019

Objectives

Deep brain stimulation (DBS) of the centromedian thalamic nucleus (CM) is an emerging treatment for multiple brain diseases, including the drug-resistant epilepsy Lennox-Gastaut syndrome (LGS). We aimed to improve neurosurgical targeting of the CM by (i) developing a structural MRI approach for CM visualisation, (ii) identifying the CM’s neurophysiological characteristics, and (iii) mapping connectivity from CM-DBS sites using functional MRI (fMRI).

Methods

Nineteen patients with LGS (mean age=28 years) underwent pre-surgical 3 tesla MRI using magnetisation-prepared 2 rapid acquisition gradient echoes (MP2RAGE) and fMRI sequences; 16 proceeded to bilateral CM-DBS implantation and intraoperative microelectrode recordings (MERs) from the thalamus. CM visualisation was achieved by highlighting intrathalamic borders on MP2RAGE using Sobel edge-detection. Mixed-effects analysis compared two MER features (spike firing rate, background noise) between ventrolateral, CM, and parafasicular nuclei. Resting-state fMRI connectivity was assessed using implanted CM-DBS electrode positions as regions-of-interest.

Results

The CM appeared as a hyperintense region bordering the comparatively hypointense pulvinar, mediodorsal, and parafasicular nuclei. At the group-level, reduced spike firing and background noise distinguished CM from the ventrolateral nucleus; however, these trends were not found in 20-25% of individual MER trajectories. Areas of fMRI connectivity included basal ganglia, brainstem, cerebellum, sensorimotor/premotor and limbic cortex.

Conclusions

In the largest clinical trial cohort of LGS patients undergoing CM-DBS reported to date, we show that accurate targeting of the CM is achievable using 3 tesla MP2RAGE MRI. MERs may provide additional localising features in some cases, however their utility is limited by inter-patient variability. Therapeutic effects of CM-DBS may be mediated via connectivity with brain networks that support diverse arousal, cognitive, and sensorimotor processes.
An Environment-Wide Study of Adult Cognitive Performance in the 23andMe Cohort
Authors: Huang Yunru , Filshtein Teresa ,   the 23andMe Research Team, Gentleman Robert , Aslibekyan Stella
Published: October 2019

BACKGROUND

With the emergence of web-based data collection methods, large digital health cohorts offer the opportunity to conduct behavioral and epidemiologic research at an unprecedented scale. The size and breadth of such data sets enable discovery of novel associations across the phenotypic spectrum.

METHODS

We deployed the digital symbol substitution test (DSST) online to consented 23andMe research participants 50-85 years of age. We tested cross-sectional associations between DSST performance and 824 phenotypes using linear regression models adjusted for age, sex, age*sex interaction, device, time of cohort entry, and ancestry, separately among discovery (n=144,786) and replication (n=93,428) samples; additional analyses further adjusted for education. We post-stratified association estimates on age, sex, and education to adjust for discrepancies across subsamples. Leveraging the rich genetic and phenotypic data available at 23andMe, we also estimated genetic and environmental correlations between DSST and its top correlates using linkage disequilibrium score regression.

RESULTS

97 phenotypes were significantly (false discovery rate < 0.05) and strongly (standardized effect size > |0.5|) associated with DSST performance in the discovery phase. Of those, 60 (38 with additional adjustment for education) demonstrated both statistical significance and consistent direction of association in the replication sample. The significantly associated phenotypes largely clustered into the following categories: psychiatric traits (e.g. anxiety, β per 1 SD = −0.74, P-value=3.9×10−169), education (e.g. highest math class completed, β per 1 SD = 2.11, P-value<1 × 10−300), leisure activities (e.g. solitary activities like puzzles, β per 1 SD = 1.85, P-value<1.0×10−300), social determinants (e.g. household income, β per 1 SD = 1.20, P-value= 8.9×10−245, and lifestyle (e.g. years smoked, β per 1 SD = −0.98, P-value= 2.2×10−78). We identified several reproducible genetic correlations between DSST and its top associated exposures (e.g. 0.48 for leisure activities like puzzles, 0.28 for years of education, and −0.24 for anxiety; all P ≤ 7.9×10−26). For almost all exposures, genetic correlations with DSST were considerably stronger than environmental correlations.

CONCLUSIONS

We have conducted the largest study of cognitive performance to date, building evidence supporting its correlations with many social, lifestyle, and clinical exposures. We established that the observed associations are in part underpinned by shared genetic architecture. Our study illustrates the potential of large-scale digital cohorts to contribute to epidemiologic discovery.
Increasing Firearm Deaths in The Youngest Americans: Ecologic Correlation with Firearm Prevalence
Authors: Bleyer Archie , Siegel Stuart , Thomas Charles R.
Published: October 2019

Background

In the United States (U.S.), the overall death rate in 1-4 year-olds had been steadily declining until 2011, after which it ceased to improve. To understand this trend reversal, we investigated trends in the causes of their deaths.

Methods

Mortality data were obtained from the U.S. Centers for Disease Control and Institute for Health Metrics and Evaluation, firearm background check data from the National Instant Criminal Background Check System, and civilian firearm prevalence from the Small Arms Survey.

Findings

In 1-4 year-olds, the rate of fatal firearm accidents during 2002-2017 increased exponentially at an average rate of 6.0%/year (p=0.0003). The rate of increase was the greatest of all evaluable causes of death in the age group. Both the rate increase and most recent absolute rate in firearm accidental deaths in young children were correlated with the concurrent corresponding rate of firearm background checks (p = 0.0002 and 0.003, respectively). Also, the firearm accidental death rate in countries with high civilian firearm prevalence was correlated with the number of guns per civilian population (p=0.002).

Interpretation

Prior to 2004, the childhood firearm death rate did not increase during the Federal Assault Weapons Ban. Since 2004 when the Ban ended, the steadily increasing rate of sales and concomitant availability of, and access to, firearms in the U.S. has been associated with an increase in fatal firearm accidents in its youngest children. The acceleration of firearm deaths and injuries among young Americans requires urgent, definitive solutions that address firearm prevalence.

Funding

No external funding.

KEY POINTS

Question

In the U.S., how has the escalation of both firearm sales and firearm death rates affected the country’s youngest population?

Findings

While the steadily increasing rate of sales and concomitant availability of, and access to, firearms in the U.S. has increased since 2004, fatal firearm accidents in 1 to 4 year-olds increased exponentially and at a rate greater than all other evaluable causes of death in the age group.

Interpretation

The ominous acceleration of firearm deaths and injuries among young Americans requires urgent, definitive solutions from multiple stakeholders to effectively reduce firearm access.
Legionella pneumophilainfection and antibiotic treatment engenders a highly disturbed pulmonary microbiome with decreased microbial diversity
Authors: Pérez-Cobas Ana Elena , Ginevra Christophe , Rusniok Christophe , Jarraud Sophie , Buchrieser Carmen
Published: October 2019

Background

Lung microbiome analyses have shown that the healthy lung is not sterile but it is colonized like other body sites by bacteria, fungi and viruses. However, little is known about the microbial composition of the lung microbiome during infectious diseases such as pneumonia and how it evolves during antibiotic therapy. To better understand the impact of the composition of the pulmonary microbiome on severity and outcome of pneumonia we analysed the composition and evolution of the human lung microbiome during pneumonia caused by the bacteriumLegionella pneumophila.

Results

We collected 10 bronchoalveolar lavage (BAL) samples from three patients during long-term hospitalisation due to severe pneumonia and performed a longitudinal in-depth study of the composition of their lung microbiome by high-throughput Illumina sequencing of the 16S rRNA gene (bacteria and archaea), ITS region (fungi) and 18S rRNA gene (eukaryotes). We found that the composition of the bacterial lung microbiome during pneumonia is hugely disturbed containing a very high percentage of the pathogen, a very low bacterial diversity, and an increased presence of opportunistic microorganisms such as species belonging to Staphylococcaceae and Streptococcaceae. The microbiome of antibiotic treated patients cured from pneumonia represented a different perturbation state with a higher abundance of resistant bacteria (mainly Firmicutes) and a significantly different bacterial composition as that found in healthy individuals. In contrast, the mycobiome remains more stable during pneumonia and antimicrobial therapy. Interestingly we identified possible cooperation within and between both communities. Furthermore, archaea (Methanobrevibacter) and protozoa (AcanthamoebaandTrichomonas) were detected.

Conclusions

Bacterial pneumonia leads to a collapse of the healthy microbiome and a strongly disturbed bacterial composition of the pulmonary microbiome that is dominated by the pathogen. Antibiotic treatment allows some bacteria to regrow or recolonize the lungs but the restoration of a healthy lung microbiome composition is only regained a certain time after the antibiotic treatment. Archaea and protozoa should also be considered, as they might be important but yet overseen members of the lung microbiome. Interactions between the micro- and the mycobiome might play a role in the restoration of the microbiome and the clinical evolution of the disease.
The itch-scratch reflex generates protective immunity
Authors: Radjavi Ali , Lebeau Anna-Marie , Mcoy Henry P.
Published: October 2019

Itch: its complex neurobiology, its exquisite evolutionary conservation, and even the undeniably euphoric sensation of the scratch it evokes, are all suggestive of a productive physiological function. Nevertheless, we still struggle to answer (or altogether overlook) the basic question of why we itch in the first place. Here, we propose a simple hypothesis: the purpose of itch sensation is to evoke scratching behavior, which in turn boosts protective immunity against the broad range of pathogenic challenges that enter at the skin. We propose that the key function of itch induced scratching is to physically disrupt the skin, serving as a “mechanical adjuvant” that amplifies and directs immune responses to the precise site of potential pathogen entry. As proof of principle, we show that the potent adjuvanticity of itch inducing Compound 48/80 is dependent on this agent’s ability to elicit scratching behavior.
Topological inference from spontaneous activity structures in FMRI videos with peristence barcodes
Authors: Don Arjuna P.H. , Peters James F. , Ramanna Sheela , Tozzi Arturo
Published: October 2019

Spatio-temporal brain activities with variable delay detectable in resting-state functional magnetic resonance imaging (rs-fMRI) give rise to highly reproducible structures, termed cortical lag threads, that can propagate from one brain region to another. Using a computational topology of data approach, we found that Betti numbers that are cycle counts and the areas of vortex cycles covering brain activation regions in triangulated rs-fMRI video frames make it possible to track persistent, recurring blood oxygen level dependent (BOLD) signals. Our findings have been codified and visualized in what are known as persistent barcodes. Importantly, a topology of data offers a practical approach in coping with and sidestepping massive noise in neuro data, such as unwanted dark (low intensity) regions in the neighbourhood of non-zero BOLD signals. A natural outcome of a topology of data approach is the tracking of persistent, non-trivial BOLD signals that appear intermittently in a sequence of rs-fMRI video frames. The end result of this tracking of changing lag structures is a persistent barcode, which is a pictograph that offers a convenient visual means of exhibiting, comparing and classifying brain activation patterns.
Full-waveform inversion imaging of the human brain
Authors: Guasch Lluís , Calderón Agudo Oscar , Tang Meng-Xing , Nachev Parashkev , Warner Michael
Published: October 2019

Magnetic resonance imaging and X-ray computed tomography provide the two principal methods available for imaging the brain at high spatial resolution, but these methods are not easily portable and cannot be applied safely to all patients. Ultrasound imaging is portable and universally safe, but existing modalities cannot image usefully inside the adult human skull. We use in-silico simulations to demonstrate that full-waveform inversion, a computational technique originally developed in geophysics, is able to generate accurate three-dimensional images of the brain with sub-millimetre resolution. This approach overcomes the familiar problems of conventional ultrasound neuroimaging by using: transcranial ultrasound that is not obscured by strong reflections from the skull, low frequencies that are readily transmitted with good signal-to-noise ratio, an accurate wave equation that properly accounts for the physics of wave propagation, and an accurate model of the skull that compensates properly for wavefront distortion. Laboratory ultrasound data, using ex-vivo human skulls, demonstrate that our computational experiments mimic the penetration and signal-to-noise ratios expected in clinical applications. This form of non-invasive neuroimaging has the potential for the rapid diagnosis of stroke and head trauma, and for the provision of routine monitoring of a wide range of neurological conditions.
Gamma band oscillations drives information flow in theta and delta band between hippocampus and medial pre-frontal cortex
Authors: I.B.H. Samuel
Published: October 2019

Information flow in the brain is mediated by neuronal oscillations. Prior research has shown that gamma activity considered to be most reflective of neuronal firing is nested within theta cycles. This finding has given rise to the notion that theta phase mediates the gamma oscillations and thereby paces information flow. Such findings have been observed predominantly in cases where the gamma and theta oscillations were measured from the same underlying neuronal substrate. In this article, we analyze the across region, inter-brain coupling of gamma and theta oscillations using non-directional and directional connectivity measures. We show that in this context the information flow appears to be mediated by gamma oscillations which in turn drives the theta and delta oscillations. Additionally, different bands of gamma are coupled with theta and delta bands. During task, this information flow is enhanced compared to baseline in the frequencies which are coupled. Furthermore, the connectivity measures namely cross-frequency coupling and generalized partial directed coupling are not correlated with each other suggesting that they maybe representative of different underlying neuronal mechanisms.
Discovery of synthetic lethal interactions from large-scale pan-cancer perturbation screens
Authors: Srivatsa Sumana , Montazeri Hesam , Bianco Gaia , Coto-Llerena Mairene , Ng Charlotte KY , Piscuoglio Salvatore , Beerenwinkel Niko
Published: October 2019

Despite the progress in precision oncology, development of cancer therapies is limited by the dearth of suitable drug targets1. Novel candidate drug targets can be identified based on the concept of synthetic lethality (SL), which refers to pairs of genes for which an aberration in either gene alone is non-lethal, but co-occurrence of the aberrations is lethal to the cell. We developed SLIdR (Synthetic Lethal Identification in R), a statistical framework for identifying SL pairs from large-scale perturbation screens. SLIdR successfully predicts SL pairs even with small sample sizes while minimizing the number of false positive targets. We applied SLIdR to Project DRIVE data2 and found both established and novel pan-cancer and cancer type-specific SL pairs. We identified and experimentally validated a novel SL interaction between AXIN1 and URI1 in hepatocellular carcinoma, thus corroborating the potential of SLIdR to identify new SL-based drug targets.
The concerted emergence of well-known spatial and temporal ecological patterns in an evolutionary food web model in space
Authors: Hamm Michaela , Drossel Barbara
Published: October 2019

Ecological systems show a variety of characteristic patterns of biodiversity in space and time. It is a challenge for theory to find models that can reproduce and explain the observed patterns. Since the advent of island biogeography these models revolve around speciation, dispersal, and extinction, but they usually neglect trophic structure. Here, we propose and study a spatially extended evolutionary food web model that allows us to study large spatial systems with several trophic layers. Our computer simulations show that the model gives rise simultaneously to several biodiversity patterns in space and time, from species abundance distributions to the waxing and waning of geographic ranges. We find that trophic position in the network plays a crucial role when it comes to the time evolution of range sizes, because the trophic context restricts the occurrence and survival of species especially on higher trophic levels.
Anatomically informed bayesian spatial priors for fmri analysis
Authors: Abramian David , Sidén Per , Knutsson Hans , Villani Mattias , Eklund Anders
Published: October 2019

Existing Bayesian spatial priors for functional magnetic resonance imaging (fMRI) data correspond to stationary isotropic smoothing filters that may oversmooth at anatomical boundaries. We propose two anatomically informed Bayesian spatial models for fMRI data with local smoothing in each voxel based on a tensor field estimated from aT1-weighted anatomical image. We show that our anatomically informed Bayesian spatial models results in posterior probability maps that follow the anatomical structure.
The TES beamline (8-BM) at NSLS-II: tender-energy spatially resolved X-ray absorption spectroscopy and X-ray fluorescence imaging
Authors: Northrup Paul
Published: October 2019

The tender-energy X-ray spectroscopy (TES) beamline at the National Synchrotron Light Source II (NSLS-II) is now operational for general users. Its scientific mission includes static and in situ X-ray fluorescence imaging and spatially resolved X-ray absorption spectroscopy for characterization of complex heterogeneous, structured and dynamic natural or engineered materials and systems. TES is optimized for the tender-energy range, offering routine operations from 2.0 to 5.5 keV, with capabilities to reach down to 1.2 or up to 8 keV with configuration change. TES is designed as an extended X-ray absorption fine-structure microprobe (EXAFS microprobe) for applications of micrometre-scale EXAFS spectroscopy to heterogeneous samples. Beam size is user-tunable from ∼2 to 25 µm. Energy may be scanned on-the-fly or in traditional step scanning. Importantly, the position of the microbeam at the sample location does not move significantly during energy scanning or when changing energy across the entire routine energy range. This enables full EXAFS of a particle or domain the same size as the probe beam, and measurement of the same spot at different energies. In addition, there is no measureable drift in energy calibration (repeatability) scan-to-scan and over 24 h. This is critical where simultaneous calibration measurements are generally not feasible, and for speciation mapping where precise and stable control of incident energy is essential. The sample environment is helium atmosphere at room pressure with infrastructure for in situ electrochemistry and catalysis in small sample cells or microreactors. As the first bend-magnet beamline at NSLS-II, noteworthy commissioning aspects are described. Example measurements are presented to illustrate its capabilities.
Capital and credit constraints in the engagement of youth in Ghanaian agriculture
Authors: Ankrah Twumasi Martinson , Jiang Yuansheng , Owusu Acheampong Monica
Published: October 2019

Purpose

The purpose of this paper is to determine the factors influencing rural youth farmers’ credit constraints status and the effect of credit constraint on the intensity of participation of these farmers in Ghana.

Design/methodology/approach

The econometric estimation is based on cross-sectional data collected in 2018 from the Brong Ahafo region in Ghana. The sample data set consists of 450 rural youth farmers. The collected data were analyzed through different econometric techniques, using the endogenous switching regression model (ERSM).

Findings

The direct elicitation approach employed in this study revealed that out of the 450 farmers, 211 (47 percent) of the respondents were credit constrained compared to 239 (53 percent) of their counterparts who were unconstrained. The ERSM indicated that youth farmers education, age, savings, parents occupation reduced the probability of the rural youth farmer to be credit constrained but cumbersome loan application procedure and loan disbursement time positively affect credit constraint. Moreover, farmers that are credit constrained have lower intensity of participation in agriculture activities than a random farmer from the sample. This suggests that access to credit has a positive impact on the intensity of participation in agriculture activities.

Research limitations/implications

In this study, only rural youth farmers in a particular region were considered. However, there are youths all over the nation. Therefore, future researchers could consider other youth’s farmers elsewhere in the country.

Originality/value

Although existing studies have examined rural youth farmers’ participation in agriculture and credit constraint separately, the unique contribution of this paper is the analysis of credit constraint of rural youth farmers as well as the impact of credit constraint on the intensity of participation in agriculture activities.
Linking national business system and firm level innovation
Authors: Ahmad Bashir , Erçek Mehmet
Published: October 2019

Purpose

The purpose of this paper is to explain the link between national business system (NBS) and innovation decisions at the firm level by offering sequentially ordered sense-making mechanisms that enable the formation of firm-specific knowledge repositories and knowledge-processing capabilities.

Design/methodology/approach

This study engages in an extensive scale development effort to collect representative data about the NBS in the Pakistani setting, complemented by relevant validity and reliability tests. The overall theoretical model was tested on 214 firms by means of a structural equation modeling approach, using partial least-squares algorithms.

Findings

The results statistically supported the role of firm-level knowledge repositories (intellectual capital) and knowledge exploration and exploitation capabilities (absorptive capacity) as sequential mediators in the association of NBS and firm-level innovation. Besides, bridging networks of lateral ties among Pakistani businesses are found to be more effective than bonding networks of vertical ties in encouraging radical innovations.

Originality/value

This study significantly extends the literature about the NBS approach. It provides specific sense-making mechanisms (i.e. priming, triggering and editing) about how abstract institutional templates constituted at the business system level are translated into firm-level actionable sets by the help of intangible resource repositories and processes that guide knowledge exploration and exploitation.
IFRS adoption, value relevance and conditional conservatism: evidence from China
Authors: Isaboke Cyrus , Chen Yan
Published: October 2019

Purpose

This study sought to evaluate the relationship between value relevance of financial information and conditional conservatism of non-financial companies listed in China.

Design/methodology/approach

Using panel data comprising of 28,723 firm years, the authors determine the value relevance of financial information before and after mandatory International Financial Reporting Standards (IFRS) adoption while incorporating the relationship with conditional conservatism. The authors further examined how this relationship varies between state and non-state owned companies.

Findings

Conditional conservatism is positively (negatively) related to value relevance prior (post) to mandatory IFRS adoption while it makes no difference as to whether a company is state or non-state owned, as IFRS has a positive and significant effect on value relevance. Conservatism, on the other hand, has a negative and insignificant relationship with market value of both state and non-state owned firms during the pre- and post-IFRS period.

Originality/value

By exploring an emerging economy, the authors provide evidence on the variations in value relevance amongst state and non-state owned firms. In particular, the authors establish the positive effect of IFRS on the value relevance of non-state firms as compared to state-owned institutions.
Online investment forum and the market response around earnings announcement in the Chinese stock markets
Authors: Hao Qian , Dong Dayong , Wu Keke
Published: October 2019

Purpose

This paper aims to study the following two questions. Do earnings announcements stimulate investors to participate in online discussions? Does online investment forum participation affect the market’s reaction to earnings news?

Design/methodology/approach

The authors collect all the online posts, which were related to the internet service companies and posted in a Chinese financial forum, guba.eastmoney.com (Guba), during the period between June 30, 2008 and December 31, 2015. Multiple linear regression analysis is used to test the questions.

Findings

The study finds that the earnings announcements induce online discussion. In addition, before the earnings announcement, online posting activity does not affect earnings response coefficient but can weaken the positive association between the magnitude of the upcoming earnings surprise and abnormal trading volume. In contrast, after the earnings announcement, online forum participation can facilitate the incorporation of earnings surprise into the price.

Originality/value

This study contributes to the literature studying the impact of social media on market reaction to earnings news by providing evidence that the price discovery process can be affected by the online investment forum. Several policy implications are also provided.
Gait planning and control of quadruped crawling robot on a slope
Authors: Wang Peng , Song Chunxiao , Li Xiaoqiang , Luo Peng
Published: October 2019

Purpose

The gait planning and control of quadruped crawling robot affect the stability of the robot walking on a slope. The control includes the position control in the swing phase, the force control in the support phase and the switching control in the force/position switching. To improve the passing ability of quadruped crawling robot on a slope, this paper aims to propose a soft control strategy.

Design/methodology/approach

The strategy adopts the statically stable crawling gait as the main gait. As the robot moves forward, the position/force section switching control is adopted. When the foot does not touch the ground, the joint position control based on the variable speed PID is performed. When the foot touches the ground, the position-based impedance control is performed, and a fuzzy multi-model switching control based on friction compensation is proposed to achieve smooth switching of force and position.

Findings

The proposed method offers a solution for stable passage in slope environment. The quadruped crawling robot can realize smooth switching of force/position, precise positioning in the swing process and soft control of force in the supporting phase. This fact is verified by simulation and test.

Originality/value

The method presented in this paper takes advantage of minimal tracking errors and minimal jitters. Simulations and tests were performed to evaluate the performance.
Profit or loss? On the determinants of net income of United States college football programs
Authors: Omondi-Ochieng Peter
Published: October 2019

Purpose

This study aims to predict the determinants of net income of 101 US university football programs.

Design/methodology/approach

Guided by stakeholder theory, financial capacity model and resource dependency theory, the dependent variable was net income (indicated as profit or loss) and independent variables were measured as the number of women and men’s team sports, average home attendances, win–loss records, conference ranking, endowment funds and age of football programs. Statistical analysis was performed using Kendell tau and binary logistic regression (BLR).

Findings

Net income was positively and statistically associated with home attendance, win–loss record, conference rankings and endowment funds, but not number of women’s sports, age of football program and number of men’s sports teams. The BLR indicated that home attendance was the best predictor of net income.

Research limitations/implications

The research was delimited to 101 Football Bowl Subdivision football programs from public universities.

Practical implications

The findings indicate that home attendance and conference rankings had the highest association with net income, but the former was the best predictor of net income and not football tradition nor number of sports teams.

Originality/value

The study was pioneering in the predictive evaluation of the possible determinants of loss or profitability in college football programs.