bluuebunny/crossref_metadata_2025 huggingface dataset:
An Update of N-Tosylhydrazones: Versatile Reagents for Metal-Catalyzed and Metal-Free Coupling Reactions
Authors: Deng Yu-Hua , Shao Zhihui , Wang Hui
Published: May 2018

N-Tosylhydrazones have had widespread application in organic synthesis for more than a half century. In most of cases, N-tosylhydrazones, as masked diazo compounds, have been generally used in a series of important carbon–carbon and carbon–heteroatom bond-forming reactions. This review provides an update on progress in diverse coupling reactions of N-tosylhydrazones since 2012. The examples selected are mainly categorized by metal-catalyzed and metal-free systems, wherein four main types of transformations including insertion, olefination, alkynylation, and cyclization are discussed for each system.

1 Introduction

2 Transition-Metal-Catalyzed Coupling Reactions

3 Metal-Free Coupling Reactions

4 Conclusion and Outlook
Recent Advances in Intermolecular Hydroacylation of Alkenes with Aldehydes through Rhodium Catalysis
Authors: Zhang Guozhu , Guo Rui
Published: May 2018

The rhodium-catalyzed intermolecular hydroacylation of alkenes with aldehydes is an atom-economical method for the synthesis of ketones. Here, we give a brief review on its development and we highlight recent advances in chelating strategies for the stabilization of acyl rhodium species by coordinative saturation.
Ultrasound-Guided Treatment of Peripheral Nerve Pathology
Authors: Dettori Nathan , Choudur Hema , Chhabra Avneesh
Published: May 2018

High-resolution ultrasound serves as a fast, accessible, reliable, and radiation-free tool for anatomical and dynamic evaluation of various peripheral nerves. It can be used not only to identify and diagnose peripheral nerve and perineural pathology accurately but also to guide various nerve and perineural interventions. We describe the normal and pathologic appearances of peripheral nerves, the pathologies commonly affecting the individual peripheral nerves, and the current ultrasound-guided peripheral nerve interventions and techniques. Future directions are also highlighted.
Imaging Patterns of Muscle Atrophy
Authors: Wolf Marcel , Wattjes Mike , Weber Marc-André
Published: May 2018

The role of muscle imaging in the diagnosis of inherited and acquired muscle diseases has gained clinical relevance. In particular, magnetic resonance imaging (MRI) is increasingly being used for diagnostic purposes, especially with its capability of whole-body musculature assessment. The assessment and quantification of muscle involvement in muscle diseases can be of diagnostic value by identifying a certain involvement pattern and thus narrowing the differential diagnosis and supporting the clinical diagnosis. In addition, more recently the role of imaging has gone beyond diagnostic purposes and includes disease as well as treatment monitoring. Conventional and quantitative muscle MRI techniques allow for the detection of subclinical disease progression (e.g., in muscular dystrophies) and is a powerful surrogate outcome measure in clinical trials. We present and discuss recent data on the role of conventional and quantitative MRI in the diagnosis and monitoring of inherited dystrophic muscle diseases as well as muscle denervation.
Getting Started with Magnetic Resonance Neurography
Authors: Bolog Nicolae , Andreisek Gustav
Published: May 2018

This article provides a review of magnetic resonance neurography (MRN) and how to get started. It explains step by step how to establish MRN at an institution: how to set up MRN protocols, how to train technicians, what a report needs to contain, and how relevant findings should be communicated to the referring physician. Advanced imaging techniques such as diffusion tensor imaging are only briefly discussed at the end of the article because most of those techniques are difficult for beginners and are still not considered standard in the clinical routine.
Nerve Entrapment Syndromes at the Wrist and Elbow by Sonography
Authors: Klauser Andrea , Taljanovic Mihra , Strobl Sylvia , Rauch Stefan , Teh James , Wanschitz Julia , Löscher Wolfgang , Martinoli Carlo , Buzzegoli Tommaso
Published: May 2018

Nerve entrapment syndromes of the upper extremity are associated with structural abnormalities or by an intrinsic abnormality of the nerve. Nerve entrapment syndromes generally have a typical clinical presentation, and findings on physical examination and in conjunction with electrodiagnostic studies imaging is used to evaluate the cause, severity, and etiology of the entrapment. With the development of high-frequency linear array transducers (12–24 MHz), ultrasound (US) is incomparable in terms of spatial resolution to depict morphological aspects and changes in nerves. US can identify the abnormalities causing entrapment, such as fibrous bands, ganglia, anomalous muscles, and osseous deformities, with the advantage of dynamic assessment under active and passive examination. US is a unique diagnostic modality that allows superb visualization of both large and small peripheral terminal nerve branches of the upper extremity and enables the correct diagnosis of various nerve entrapment syndromes.
Ultrasound of the Brachial Plexus
Authors: Griffith James
Published: May 2018

Examination of the brachial plexus with ultrasound is efficient because it allows many parts of the brachial plexus as well as the surrounding soft tissues to be assessed with high spatial resolution. The key to performing good ultrasound of the brachial plexus is being familiar with the anatomy and the common variants. That makes it possible to concentrate solely on the ultrasound appearances free of simultaneously wondering about the anatomy. Ultrasound of the brachial plexus is particularly good for assessing nerve sheath tumor, perineural fibrosis, metastases, some inflammatory neuropathies, neuralgic amyotrophy, and posttraumatic sequalae. It is limited in the assessment of thoracic outlet syndrome and in the acute/subacute trauma setting. This review addresses the anatomy, ultrasound technique, as well as pathology of the brachial plexus from the cervical foramina to the axilla.
Neurology Training Worldwide
Authors: Hillis James , Berkowitz Aaron
Published: May 2018

Neurology training is essential for providing neurologic care globally. Large disparities in availability of neurology training exist between higher- and lower-income countries. This review explores the worldwide distribution of neurology training programs and trainees, the characteristics of training programs in different parts of the world, and initiatives aimed at increasing access to neurology training in under-resourced regions.
Emerging Viral Infections and Their Impact on the Global Burden of Neurological Disease
Authors: Muñoz Laura , Garcia Maria , Gordon-Lipkin Eliza , Parra Beatriz , Pardo Carlos
Published: May 2018

Emerging viral infections of the nervous system represent a major global public health concern in the 21st century. They are caused primarily by RNA viruses and are mostly associated with acute or subacute encephalitis. The spectrum of associated central or peripheral nervous system disorders is broad, and results either from a direct viral effect or due to the host immune responses against the infection. Emerging viral infections impose substantial neurological morbidity and mortality, particularly in low- and middle-income regions. In the past five decades, vector-borne viruses primarily transmitted by arthropods, or arboviruses, have been responsible for epidemics with a high burden of neurological disease, like the 2015–2016 Zika virus epidemic in the Americas. Viruses that have become neurovirulent for humans after geographical expansion include West Nile, Dengue, and Zika viruses. Factors such as animal migration, disruption of ecological niches, and cross-species contact have caused old viruses to reappear and cause neurological disease, as is the case of Ebola virus. In addition to these biological challenges, current preventive strategies, vaccination, and diagnostic and therapeutic approaches remain limited. We review the clinical-virological features and global impact of the most relevant emerging viral infections of the nervous system as they are projected over the 21st century.
Global Health: Pediatric Neurology
Authors: Ciccone Ornella , Patel Archana , Bearden David
Published: May 2018

Neurologic disorders contribute significantly to both morbidity and mortality among children in resource-limited settings, but there are a few succinct studies summarizing the epidemiology of neurologic disorders in these settings. A review of available literature was performed to identify data on the prevalence, etiology, outcomes, and treatment of neurologic disorders in children in resource-limited settings. The burden of neurologic disorders in children is high in resource-limited settings. Barriers to optimal care include lack of trained personnel, limited access to diagnostic technology, and limited availability of drugs used to treat common conditions. Several solutions have been suggested to deal with these challenges including increased collaborations to train neurologists willing to practice in resource-limited settings and increased training of physician extenders or community health workers. Further studies are necessary to improve our understanding of the epidemiology of neurologic disorders in resource-limited settings. Future epidemiologic studies should incorporate multiple countries in resource-limited settings and utilize standardized definitions and methodologies to enable comparison across regions.
Documenting Routinely What Matters to People: Standardized Headings for Health Records of Patients with Chronic Health Conditions
Authors: Prodinger Birgit , Rastall Paul , Kalra Dipak , Wooldridge Darren , Carpenter Iain
Published: May 2018

Objective Specifying the content in electronic health records (EHRs) through standardized headings based on international reference classifications will facilitate their semantic interoperability. The objective of this study was to specify potential chapter headings for EHRs aligned with the World Health Organization's (WHO) International Classification of Functioning, Disability, and Health (ICF) based on the perspectives of people living with chronic health conditions, carers, and professionals.

Methods A multistage process was established including (1) a patient workshop, (2) an online survey of both patients and carers, and (3) an online consultation with patient and professional bodies. The ICF served as a starting point. Based on the first stage, a first draft of the headings was developed and further refined based on the feedback at each stage. We examined in a fourth step whether items from existing assessment tools support the operationalization of the identified headings. Therefore, we used the WHO Disability Assessment Schedule 2.0 (WHODAS2.0), a patient-reported instrument, and interRAI, a clinician-administered instrument.

Results The first workshop was attended by eight people, the survey was completed by 250 persons, and the online consultation received detailed feedback by 18 professional bodies. This study resulted in 16 potential chapter headings for EHRs which capture aspects related to the body, such as emotions, motivation, sleep, and memory or thoughts, to being involved in social life, such as mobility, social activities, and finances, as well as to the care process, such as understanding of health issues and treatment or care priorities and goals. When using the WHODAS2.0 and interRAI together, they capture all except one of the proposed headings.

Conclusion The identified headings provide a high level structure for the standardized recording, use, and sharing of information. Once implemented, these headings have the potential to facilitate the delivery of personalized care planning for patients with long-term health problems.
Global Burden of Stroke
Authors: Katan Mira , Luft Andreas
Published: May 2018

Stroke is the second leading cause of death and a major cause of disability worldwide. Its incidence is increasing because the population ages. In addition, more young people are affected by stroke in low- and middle-income countries. Ischemic stroke is more frequent but hemorrhagic stroke is responsible for more deaths and disability-adjusted life-years lost. Incidence and mortality of stroke differ between countries, geographical regions, and ethnic groups. In high-income countries mainly, improvements in prevention, acute treatment, and neurorehabilitation have led to a substantial decrease in the burden of stroke over the past 30 years. This article reviews the epidemiological and clinical data concerning stroke incidence and burden around the globe.
The Pediatric Emergency Care Applied Research Network Registry: A Multicenter Electronic Health Record Registry of Pediatric Emergency Care
Authors: Deakyne Davies Sara , Grundmeier Robert , Campos Diego , Hayes Katie , Bell Jamie , Alessandrini Evaline , Bajaj Lalit , Chamberlain James , Gorelick Marc , Enriquez Rene , Casper T. , Scheid Beth , Kittick Marlena , Dean J. , Alpern Elizabeth ,   the Pediatric Emergency Care Applied Research Network
Published: May 2018

Background Electronic health record (EHR)-based registries allow for robust data to be derived directly from the patient clinical record and can provide important information about processes of care delivery and patient health outcomes.

Methods A data dictionary, and subsequent data model, were developed describing EHR data sources to include all processes of care within the emergency department (ED). ED visit data were deidentified and XML files were created and submitted to a central data coordinating center for inclusion in the registry. Automated data quality control occurred prior to submission through an application created for this project. Data quality reports were created for manual data quality review.

Results The Pediatric Emergency Care Applied Research Network (PECARN) Registry, representing four hospital systems and seven EDs, demonstrates that ED data from disparate health systems and EHR vendors can be harmonized for use in a single registry with a common data model. The current PECARN Registry represents data from 2,019,461 pediatric ED visits, 894,503 distinct patients, more than 12.5 million narrative reports, and 12,469,754 laboratory tests and continues to accrue data monthly.

Conclusion The Registry is a robust harmonized clinical registry that includes data from diverse patients, sites, and EHR vendors derived via data extraction, deidentification, and secure submission to a central data coordinating center. The data provided may be used for benchmarking, clinical quality improvement, and comparative effectiveness research.
Meniscus Repair in Children and Adolescents: A Systematic Review of Treatment Approaches, Meniscal Healing, and Outcomes
Authors: Ferrari Márcio Balbinotti , Murphy Colin P. , Gomes João Luiz Ellera
Published: May 2018

Although the consequences of traumatic meniscus tears and the importance of meniscal repair are well-established in adults, the same cannot be said for the young population. Better evidence regarding the outcomes following traumatic meniscal tears in children would improve our understanding of this increasing pathology and help define important factors in deciding the best treatment option. A systematic review was performed according to the Preferred Reporting Items for Systematic Review and Meta-Analysis guidelines using the Cochrane Database of Systematic Review, Cochrane Central Register of Controlled Trials, MEDLINE Ovid, and MEDLINE PubMed databases. Inclusion criteria were as follows: studies reporting the outcomes of meniscal repair in patients 18 years old or younger, with a minimum mean follow-up of 12 months, Portuguese, Spanish, or English languages, and human studies including 10 or more patients. Our search identified 2,534 individual titles. After application of the inclusion and exclusion criteria, 8 studies were included, evaluating 287 patients with repaired meniscal tears. All eight studies were classified as level of evidence IV. The mean methodological index for nonrandomized studies score was 8.6 ± 1.4. Meniscal repair included all meniscal zones and tear patterns. Anterior cruciate ligament tear was the most common associated injury. The all-inside and inside-out techniques were predominantly reported. The majority of the patients reported good to excellent outcomes and had clinical signals of meniscal healing; meniscectomies following meniscal repair were performed in just 44 cases. In conclusion, meniscal tears in pediatrics are not uncommon. Repairs of this injury were associated with good to excellent outcomes in most patients, regardless of the injury pattern, zone, or technique. Reported complications were minimal; however, higher quality studies are needed to confirm the findings of this systematic review. This is a systematic review study with Level IV.
Return to Sport after ACL Surgery: A Comparison between Two Different Reconstructive Techniques
Authors: Baldassarri Matteo , Perazzo Luca , Ghinelli Diego , Ricciarelli Marco , Pilla Federico , Buda Roberto
Published: May 2018

The anterior cruciate ligament reconstruction (ACLR) has become a very common surgical procedure. One of the main success indicators of the surgical procedure is the return to preinjury sporting level. In recent years, reconstructive techniques have been geared toward less morbidity and optimized ligaments process to speed up the recovery of sports activity. This study compares clinical and imaging data, to evaluate the timing of return to sport, of two populations undergoing ACLR using two different techniques: ACLR with hamstring maintaining tibial insertion (MHG) and an all-inside technique with complete hamstring detachment (DHG). Patients were clinically evaluated with Marx rating scale, International Knee Documentation Committee (IKDC) score, and Tegner activity scale at a minimum follow-up (FU) of 4 years. The two groups have homogeneous characteristics: age, sex, type, and level of sports activity. Since November 2012, 59 patients with unilateral ACL insufficiency underwent ACLR: 31 patients using the MHG technique and 28 patients using the DHG technique. In both groups, a significant improvement in the clinical scores of the administered tests was observed. The MHG group reported a higher percentage of normal knees (83.8%) compared with the DHG group (78.6%). IKDC subjective score improved at each FU. Comparing the two techniques, at 12 months' FU the MHG group achieved better IKDC results (89.6) compared with the DHG technique (84.2). Marx and Tegner score values improved over time reaching comparable results at final FU. At final FU, 98% of patients returned to the same preinjury professional sporting level. Both techniques have been able to provide good clinical results. The MHG group, however, had a resumption of sports activity of the same level and intensity slightly longer (6.3 months) than that in the DHG group (5.9 months). Furthermore, the resumption of training and athletic gestures for the type of sport practiced was earlier than the DHG group. However, in the long run the level of sporting activity leveled in both groups, demonstrating the effectiveness of both techniques.
Dyspnea in the Supine Position after Anterior Cervical Discectomy and Fusion
Authors: Zhang Hua
Published: May 2018

Posterior occipitocervicothoracic fusion in a flexed position may cause dyspnea, and the onset of obstructive sleep apnea after anterior upper cervical fusion. However, there are no reports of dyspnea occurring after anterior lower cervical fusion. Here, we present an unusual case of dyspnea in the supine position after a C5-C6 anterior cervical discectomy and fusion.
Radiographic Diagnosis of Scapholunate Diastasis in Distal Radius Fractures: Implications for Surgical Practice
Authors: Özkan Sezai , Korteweg Julian , Bloemers Frank , DiGiovanni Nicholas , Mudgal Chaitanya
Published: May 2018

Background Radiographic diagnosis of scapholunate ligament injury (SLI) in the setting of distal radius fractures (DRFs) is challenging. It remains unclear to what extent radiographic diagnosis of SLI by a radiologist influences surgical decision-making regarding treatment of SLI.

Purpose We aimed to (1) identify the number of times that concerns for the possibility of concurrent SLI in the setting of a DRF had been raised by the radiologists, (2) identify how often the radiologist's diagnosis was confirmed by the treating surgeon, and (3) how many of the patients with a radiographic concern for SLI by the radiologist received operative treatment for the SLI.

Patients and Methods Based on Current Procedural Terminology codes, we identified 2,923 patients that were operatively treated for their DRF in 1 of 3 participating institutions in an urban city in the United States. We reviewed the medical charts of 654 patients who had a mention of scapholunate ligament (SL) distance in their radiography, surgery, or clinical notes. We then measured the SL distance and recorded patient, diagnosis, and treatment characteristics of all these patients.

Results A total of 200 out of 2,923 patients (6.8%) received a radiological diagnosis of SLI. In seven of these patients (3.5%), the surgeon confirmed the diagnosis of the radiologist. Four patients (2%) had operative repair of their SLI.

Conclusion Radiologists demonstrate a low threshold to identify SLI in the setting of DRFs, while the number of SLIs identified by the treating surgeon is a remarkably smaller number.

Level of Evidence Level II, prognostic study.
Skin Punctures in Preterm Infants in the First 2 Weeks of Life
Authors: Butler Daryl , Sheehan Orla , Livingstone Vicki , Dempsey Eugene , Finn Daragh
Published: May 2018

Objective The objective of this study was to investigate frequency and trends of skin punctures in preterm infants.

Study Design A prospective audit of preterm infants less than 35 weeks admitted over a 6-month period to a tertiary neonatal intensive care unit. Each skin puncture performed in the first 2 weeks of life was documented in a specifically designed audit sheet.

Results Ninety-nine preterm infants were enrolled. Infants born at < 32 weeks' gestation had significantly more skin punctures than infants > 32 weeks (median skin punctures 26.5 vs. 17, p-value < 0.05). The highest frequency of skin punctures occurred during the first week of life for infants > 28 weeks' gestation (medians 17.5 in 28–31 + 6 weeks' gestation, and 15 in > 32 weeks), and during the second week of life for those born at < 28 weeks (median 17.5). Infants with sepsis had more skin punctures (p-value < 0.001), but this was not significant on multivariate analysis. Median skin punctures in the second week of life were statistically higher in the sepsis group on multivariate analysis (odds ratio: 1.07, 95% confidence interval: 1.00–1.14, p = 0.041).

Conclusion Frequency of skin punctures is influenced by gestational age and postnatal age. Skin punctures were not an independent risk factor for sepsis.
The Impact of Frailty on Postoperative Cardiopulmonary Complications in the Emergency General Surgery Population
Authors: Akyar Serra , Armenia Sarah , Ratnani Parita , Merchant Aziz
Published: May 2018

Background The burden of frail patients undergoing emergency general surgery (EGS) is increasing rapidly and this population is particularly susceptible to postoperative cardiopulmonary complications and mortality. We aimed to determine the association between frailty, as defined by the previously described modified frailty index (mFI), and postoperative respiratory complications (unplanned reintubation, pneumonia, and prolonged ventilation), cardiac complications (myocardial infarction and cardiac arrest), and mortality. We also sought to identify the most significant determinants of frailty in the highest risk patients based on the specific variables comprising the mFI.

Methods We performed a retrospective observational analysis of the prospectively collected American College of Surgeons National Surgical Quality Improvement Program database. Files from 2005 to 2015 identified 132,765 inpatients who underwent EGS. mFI scores were calculated for each patient. The effect of increasing frailty on unplanned reintubation, pneumonia, prolonged ventilation, myocardial infarction, cardiac arrest, and mortality was evaluated using bivariate analysis. Multivariable logistic regression was used to compare mFI with additional predictor variables including race, gender, physical status as defined by the American Society of Anesthesiologists, disseminated cancer, renal failure, smoking status, sepsis, wound presence/classification, dyspnea, and previous ventilator dependence.

Results Unplanned reintubation, pneumonia, prolonged ventilation, myocardial infarction, cardiac arrest, and mortality were significantly associated with frailty, and the odds of each postoperative complication increased with increasing mFI score. Of the frailest patients (mFI ≥3) that experienced cardiopulmonary complications or mortality, the variables of the mFI that contributed most to frailty were hypertension requiring medication and functional status before surgery.

Conclusions A higher mFI score is associated with increased odds of postoperative cardiopulmonary complications and mortality in the EGS population. Specific variables of the mFI can also provide valuable information for assessing odds in the frailest patients undergoing EGS.
Symmetry breaking: Abnormal transport induced by mass modulation
Authors: Chen Ruyin , Nie Linru , Chen Chongyang
Published: May 2018

Here, we investigate transport of an inertial particle in a symmetric periodic potential and subjected to an external signal, such that mass of the particle is modulated sinusoidally. Our numerical results indicate that the mass modulation can induce abnormal transport in the system, whereas no current appears in the case of constant mass. In the absence of external bias, direction of mean velocity of the particle changes several times as amplitude and frequency of the mass modulation are varied, i.e., a multiple current reversals (CR) phenomenon. The multiple CRs result from temporal symmetry breaking of the system. In the presence of external bias, multiple absolute negative mobilities (ANM) take place in the system. Intrinsic physical mechanisms responsible for the occurrence of the multiple ANMs are analyzed in detail.
Quantum mechanics on periodic and non-periodic lattices and almost unitary Schwinger operators
Authors: Arik Metin , Ildes Medine
Published: May 2018

In this work, we uncover the mathematical structure of the Schwinger algebra and introduce almost unitary Schwinger operators which are derived by considering translation operators on a finite lattice. We calculate mathematical relations between these algebras and show that the almost unitary Schwinger operators are equivalent to the Schwinger algebra. We introduce new representations for MN(C) in terms of these algebras.
Numerical simulations on active shielding methods comparison and wrapped angle optimization for gradient coil design in MRI with enhanced shielding effect
Authors: Wang Yaohui , Xin Xuegang , Guo Lei , Chen Zhifeng , Liu Feng
Published: May 2018

The switching of a gradient coil current in magnetic resonance imaging will induce an eddy current in the surrounding conducting structures while the secondary magnetic field produced by the eddy current is harmful for the imaging. To minimize the eddy current effects, the stray field shielding in the gradient coil design is usually realized by minimizing the magnetic fields on the cryostat surface or the secondary magnetic fields over the imaging region. In this work, we explicitly compared these two active shielding design methods. Both the stray field and eddy current on the cryostat inner surface were quantitatively discussed by setting the stray field constraint with an ultra-low maximum intensity of 2 G and setting the secondary field constraint with an extreme small shielding ratio of 0.000 001. The investigation revealed that the secondary magnetic field control strategy can produce coils with a better performance. However, the former (minimizing the magnetic fields) is preferable when designing a gradient coil with an ultra-low eddy current that can also strictly control the stray field leakage at the edge of the cryostat inner surface. A wrapped-edge gradient coil design scheme was then optimized for a more effective control of the stray fields. The numerical simulation on the wrapped-edge coil design shows that the optimized wrapping angles for the x and z coils in terms of our coil dimensions are 40° and 90°, respectively.
Synchronization of relativistic particles in the hyperbolic Kuramoto model
Authors: Ritchie Louis M. , Lohe M. A. , Williams Anthony G.
Published: May 2018

We formulate a noncompact version of the Kuramoto model by replacing the invariance group SO(2) of the plane rotations by the noncompact group SO(1, 1). The N equations of the system are expressed in terms of hyperbolic angles αi and are similar to those of the Kuramoto model, except that the trigonometric functions are replaced by hyperbolic functions. Trajectories are generally unbounded, nevertheless synchronization occurs for any positive couplings κi, arbitrary positive multiplicative parameters λi and arbitrary exponents ωi. There are no critical values for the coupling constants. We measure the onset of synchronization by means of several order and disorder parameters. We show numerically and by means of exact solutions for N = 2 that solutions can develop singularities if the coupling constants are negative, or if the initial values are not suitably restricted. We describe a physical interpretation of the system as a cluster of interacting relativistic particles in 1 + 1 dimensions, subject to linear repulsive forces with space-time trajectories parametrized by the rapidity αi. The trajectories synchronize provided that the particle separations remain predominantly time-like, and the synchronized cluster can be viewed as a bound state of N relativistic particle constituents. We extend the defining equations of the system to higher dimensions by means of vector equations which are covariant with respect to SO(p, q).
Ionization assisted self-guiding of femtosecond laser pulses
Authors: Morozov A. , Goltsov A. , Chen Q. , Scully M. , Suckewer S.
Published: May 2018

We propose a new mechanism for the self-guiding of ultra-intense sub-picosecond laser pulses in gaseous media. It can be realized via optical field ionization by a laser pulse as it propagates inside an expanding cylindrical shock wave launched into ambient gas by a decayed plasma filament. In experiments, the filament was created in a hydrogen jet by a low energy femtosecond laser pre-pulse line focused with axicon lens. We demonstrated ionization-assisted guiding in structures with diameter as small as 14 μm and up to 3.5 mm long. The intensity reached 5 × 1017 W/cm2 in a single mode propagating for more than 100 Rayleigh lengths.
Development of improved superconductive axial gradiometers for biomagnetic SQUID applications
Authors: Budnyk M. M. , Minov Yu. D. , Lyakhno V. Yu. , Desnenko V. A. , Linnik A. S. , Shopen O. B.
Published: May 2018

SQUID magnetometers for biomagnetic measurements are equipped with superconductive gradiometers which are required to provide a high signal-to-noise ratio at low frequencies, sufficient mechanical strength and sustained performance under repeated thermal cycles, as well as a low level of intrinsic magnetic noise. This paper describes the design of a gradiometer made with a carbon-fiber reinforced composite material for magnetic cardiography measurements. The thermal coefficient of linear expansion (TCLE) of the carbon fiber composite can be precisely adjusted to match that of the superconducting detector coil wire. This is achieved thanks to the difference in the TCLE of carbon fibers in the longitudinal and transverse directions and is realized by varying the laying directions of the fiber in the composite. The data of magnetic susceptibility measurements on carbon fiber composite are reported, showing the magnetic susceptibility about six times smaller than that of graphite. The presented gradiometer design provides a high degree of balancing and is patented along side other specific techniques.
Microwave response of a cavity resonator with thin superconductor film depending on film temperature and orientation
Authors: Barannik A. A. , Cherpak N. T. , He Y. , Sun L. , Zhang X. , Vovnyuk M. V. , Wu Y.
Published: May 2018

We substantiate the earlier proposed hypothesis about the nature of an anomaly previously observed in the temperature dependence of microwave losses of a cavity resonator containing a thin superconducting film of FeSe1-xTex placed perpendicular to the magnetic field of the resonator. An experiment with a film oriented parallel to the field shows the absence of the anomaly. The appearance of the anomaly for T ≤ Tc in the case of the perpendicular orientation of the film is explained by a change in the field orientation and distribution in the film with changing temperature. Comparison of the experimental data with the theoretical model that does not take into account the field evolution in the film shows that the model is applicable to microwave impedance studies of films with a perpendicular orientation in the range from low temperatures to ∼2Tc/3. The expressions for the effective surface impedance of superconducting films in the N-state are also obtained, which are required for constructing the temperature dependence of the effective impedance in the temperature range including Tc.
First principle study of electronic structures and optical properties of Ce-doped SiO2
Authors: Cong Wei-Yan , Lu Ying-Bo , Zhang Peng , Guan Cheng-Bo
Published: May 2018

Electronic structures and optical properties of Silicon dioxide (SiO2) systems with and without cerium(Ce) dopant were calculated using the density functional theory. We find that after the Ce incorporation, a new localized impurity band appears between the valance band maximum (VBM) and the conduction band minimum (CBM) of SiO2 system, which is induced mainly by the Ce-4f orbitals. The localized impurity band constructs a bridge between the valence band and the conduction band, making the electronic transition much easier. The calculated optical properties show that in contrast from the pure SiO2 sample, absorption in the visible-light region is found in Ce-doped SiO2 system, which originates from the transition between the valence band and Ce-4f dominated impurity band, as well as the electronic transition from Ce-4f states to Ce-5d states. All calculated results indicate that Ce doping is an effective strategy to improve the optical performance of SiO2 sample, which is in agreement with the experimental results.
The effective χ parameter in polarizable polymeric systems: One-loop perturbation theory and field-theoretic simulations
Authors: Grzetic Douglas J. , Delaney Kris T. , Fredrickson Glenn H.
Published: May 2018

We derive the effective Flory-Huggins parameter in polarizable polymeric systems, within a recently introduced polarizable field theory framework. The incorporation of bead polarizabilities in the model self-consistently embeds dielectric response, as well as van der Waals interactions. The latter generate a χ parameter (denoted χ̃) between any two species with polarizability contrast. Using one-loop perturbation theory, we compute corrections to the structure factor Sk and the dielectric function ϵ^(k) for a polarizable binary homopolymer blend in the one-phase region of the phase diagram. The electrostatic corrections to S(k) can be entirely accounted for by a renormalization of the excluded volume parameter B into three van der Waals-corrected parameters BAA, BAB, and BBB, which then determine χ̃. The one-loop theory not only enables the quantitative prediction of χ̃ but also provides useful insight into the dependence of χ̃ on the electrostatic environment (for example, its sensitivity to electrostatic screening). The unapproximated polarizable field theory is amenable to direct simulation via complex Langevin sampling, which we employ here to test the validity of the one-loop results. From simulations of S(k) and ϵ^(k) for a system of polarizable homopolymers, we find that the one-loop theory is best suited to high concentrations, where it performs very well. Finally, we measure χ̃N in simulations of a polarizable diblock copolymer melt and obtain excellent agreement with the one-loop theory. These constitute the first fully fluctuating simulations conducted within the polarizable field theory framework.
Cavitation bubble nucleation induced by shock-bubble interaction in a gelatin gel
Authors: Oguri Ryota , Ando Keita
Published: May 2018

An optical visualization technique is developed to study cavitation bubble nucleation that results from interaction between a laser-induced shock and a preexisting gas bubble in a 10 wt. % gelatin gel; images of the nucleated cavitation bubbles are captured and the cavitation inception pressure is determined based on Euler flow simulation. A spherical gas cavity is generated by focusing an infrared laser pulse into a gas-supersaturated gel and the size of the laser-generated bubble in mechanical equilibrium is tuned via mass transfer of the dissolved gas into the bubble. A spherical shock is then generated, through rapid expansion of plasma induced by the laser focusing, in the vicinity of the gas bubble. The shock-bubble interaction is recorded by a CCD camera with flash illumination of a nanosecond green laser pulse. The observation captures cavitation inception in the gel under tension that results from acoustic impedance mismatching at the bubble interface interacting with the shock. We measure the probability of cavitation inception from a series of the repeated experiments, by varying the bubble radius and the standoff distance. The threshold pressure is defined at the cavitation inception probability equal to one half and is calculated, through comparisons to Euler flow simulation, at −24.4 MPa. This threshold value is similar to that from shock-bubble interaction experiments using water, meaning that viscoelasticity of the 10 wt. % gelatin gel has a limited impact on bubble nucleation dynamics.
Global positioning method based on polarized light compass system
Authors: Liu Jun , Yang Jiangtao , Wang Yubo , Tang Jun , Shen Chong
Published: May 2018

This paper presents a global positioning method based on a polarized light compass system. A main limitation of polarization positioning is the environment such as weak and locally destroyed polarization environments, and the solution to the positioning problem is given in this paper which is polarization image de-noising and segmentation. Therefore, the pulse coupled neural network is employed for enhancing positioning performance. The prominent advantages of the present positioning technique are as follows: (i) compared to the existing position method based on polarized light, better sun tracking accuracy can be achieved and (ii) the robustness and accuracy of positioning under weak and locally destroyed polarization environments, such as cloudy or building shielding, are improved significantly. Finally, some field experiments are given to demonstrate the effectiveness and applicability of the proposed global positioning technique. The experiments have shown that our proposed method outperforms the conventional polarization positioning method, the real time longitude and latitude with accuracy up to 0.0461° and 0.0911°, respectively.
Impact on electronic structure of donor/acceptor blend in organic photovoltaics by decontamination of molybdenum-oxide surface
Authors: Ito Yuta , Akaike Kouki , Fukuda Takeshi , Sato Daisuke , Fuse Takuya , Iwahashi Takashi , Ouchi Yukio , Kanai Kaname
Published: May 2018

Molybdenum oxide (MoOx) is widely used as the hole-transport layer in bulk-heterojunction organic photovoltaics (BHJ-OPVs). During the fabrication of solution-processed BHJ-OPVs on vacuum-deposited MoOx film, the film must be exposed to N2 atmosphere in a glove box, where the donor/acceptor blends are spin-coated from a mixed solution. Employing photoelectron spectroscopy, we reveal that the exposure of the MoOx film to such atmosphere contaminates the MoOx surface. Annealing the contaminated MoOx film at 160 °C for 5 min, prior to spin-coating the blend film, can partially remove the carbon and oxygen adsorbed on the MoOx surface during the exposure of MoOx. However, the contamination layer on the MoOx surface does not affect the energy-level alignment at the interface between MoOx and the donor/acceptor blend. Hence, significant improvement in the performance of BHJ-OPVs by mildly annealing the MoOx layer, which was previously reported, can be explained by the reduction of undesired contamination.
Morphology of supercooled droplets freezing on solid surfaces
Authors: La Shiren , Huang Zhiting , Liu Cong , Zhang Xingyi
Published: May 2018

Supercooled droplets freezing on solid surfaces are ubiquitous in nature. This letter investigates the influences of droplet viscosity on freezing velocity and frosting formation. Several experiments were conducted for three kinds of sessile droplets (water, silicone oil and oil) on two types of substrates (copper and iron) with different surface roughness at various temperatures. The results show that the water droplets exhibit obvious phase transition lines and their freezing speeds increase when the temperature of substrates decreases. It is found that the freezing speed is independent of the thermal conductivities of the substrates. Notably, the water droplets develop prominent bulges after freezing and subsequently nucleate to frost. In contrast, the high viscosity oil and silicone oil do not manifest an obvious phase transition line. Besides, no bulges are observed in these two kinds of droplets, suggesting that these frosting forms are of different mechanisms compared with water droplets.
A note on local BRST cohomology of Yang-Mills type theories with free Abelian factors
Authors: Barnich Glenn , Boulanger Nicolas
Published: May 2018

We extend previous work on antifield dependent local Becchi-Rouet-Stora-Tyutin (BRST) cohomology for matter coupled gauge theories of Yang-Mills type to the case of gauge groups that involve free Abelian factors. More precisely, we first investigate in a model independent way how the dynamics enters the computation of the cohomology for a general class of Lagrangians in general spacetime dimensions. We then discuss explicit solutions in the case of specific models. Our analysis has implications for the structure of characteristic cohomology and for consistent deformations of the classical models, as well as for divergences/counterterms and for gauge anomalies that may appear during perturbative quantization.
New ion source dramatically improves radioactive beams for CARIBU facility
Authors: Johnson-Groh Mara
Published: May 2018

A new Electron Beam Ion Source Charge Breeder operated with the CARIBU and ATLAS facilities dramatically reduces background contamination in radioactive beams, improving abilities of neutron-rich nuclei.
Taking the long way around: Improving continuous-time random walk precision
Authors: Liebendorfer Adam
Published: May 2018

Findings reveal that extending the timing of the intial steps of continuous-time random walks can improve how precisely these stochastic systems are timed.
Maternal and postnatal high-fat diets with high ω6 : ω3 ratios affect the reproductive performance of male offspring in the mouse
Authors: Bianconi S. , Stutz G. , Solís M. R. , Martini A. C. , Vincenti L. M. , Ponzio M. F. , Luque E. , Avendaño C. , Quiroga P. , Santillán M. E.
Published: May 2018

High-fat diets (HFDs) are an acknowledged risk factor for male subfertility, but the underlying mechanisms remain unclear. In the present study we compared the effects of two HFDs with different ω6 : ω3 ratios, one enriched with soy oil (SOD; ω6 : ω3 = 9.62) and another enriched with sunflower oil (SFOD; ω6 : ω3 = 51.55), with those of a commercial diet (CD; ω6 : ω3 = 19.87), supplied from pregnancy to adulthood, on morphometric parameters and reproductive performance in adult male mice (recommended ω6 : ω3 for rodents = 1–6). Bodyweight was significantly higher in the SFOD than CD group, and relative testicular weight was significantly lower in the SFOD than the other two groups. SFOD altered sperm performance: it reduced sperm viability (mean ± s.e.m.; 76.00 ± 1.35% vs 82.50 ± 1.45% and 80.63 ± 1.00% in the SFOD vs CD and SOD groups respectively; P < 0.05) and increased the percentage of immature spermatozoa (71.88 ± 7.17% vs 51.38 ± 5.87% and 48.00 ± 5.72% in the SFOD vs CD and SOD groups respectively; P < 0.05). The epididymal ω6 : ω3 ratio was higher in the SFOD versus CD and SOD groups, whereas the unsaturation index was higher in the SOD and SFOD groups than in CD group. Sperm membrane integrity was diminished in both the SOD and SFOD groups, but there was no difference in sperm reactive oxygen species production in these two groups compared with the CD group. The fertilisation rate was lower in the SFOD compared with the CD and SOD groups. In conclusion, although both HFDs affected sperm quality, the fertilising ability was more altered by the excessive dietary ω6 : ω3 ratio than by the net ω6 content.
Tetrodotoxin-sensitive Navs contribute to early and delayed afterdepolarizations in long QT arrhythmia models
Authors: Koleske Megan , Bonilla Ingrid , Thomas Justin , Zaman Naveed , Baine Stephen , Knollmann Bjorn C. , Veeraraghavan Rengasayee , Györke Sándor , Radwański Przemysław B.
Published: May 2018

Recent evidence suggests that neuronal Na+ channels (nNavs) contribute to catecholamine-promoted delayed afterdepolarizations (DADs) and catecholaminergic polymorphic ventricular tachycardia (CPVT). The newly identified overlap between CPVT and long QT (LQT) phenotypes has stoked interest in the cross-talk between aberrant Na+ and Ca2+ handling and its contribution to early afterdepolarizations (EADs) and DADs. Here, we used Ca2+ imaging and electrophysiology to investigate the role of Na+ and Ca2+ handling in DADs and EADs in wild-type and cardiac calsequestrin (CASQ2)-null mice. In experiments, repolarization was impaired using 4-aminopyridine (4AP), whereas the L-type Ca2+ and late Na+ currents were augmented using Bay K 8644 (BayK) and anemone toxin II (ATX-II), respectively. The combination of 4AP and isoproterenol prolonged action potential duration (APD) and promoted aberrant Ca2+ release, EADs, and DADs in wild-type cardiomyocytes. Similarly, BayK in the absence of isoproterenol induced the same effects in CASQ2-null cardiomyocytes. In vivo, it prolonged the QT interval and, upon catecholamine challenge, precipitated wide QRS polymorphic ventricular tachycardia that resembled human torsades de pointes. Treatment with ATX-II produced similar effects at both the cellular level and in vivo. Importantly, nNav inhibition with riluzole or 4,9-anhydro-tetrodotoxin reduced the incidence of ATX-II–, BayK-, or 4AP-induced EADs, DADs, aberrant Ca2+ release, and VT despite only modestly mitigating APD prolongation. These data reveal the contribution of nNaVs to triggered arrhythmias in murine models of LQT and CPVT-LQT overlap phenotypes. We also demonstrate the antiarrhythmic impact of nNaV inhibition, independent of action potential and QT interval duration, and provide a basis for a mechanistically driven antiarrhythmic strategy.
Essential surfaces in graph pairs
Authors: Wilton Henry
Published: May 2018

A well-known question of Gromov asks whether every one-ended hyperbolic group

Γ
\Gamma

has a surface subgroup. We give a positive answer when

Γ
\Gamma

is the fundamental group of a graph of free groups with cyclic edge groups. As a result, Gromov’s question is reduced (modulo a technical assumption on 2-torsion) to the case when

Γ
\Gamma

is rigid. We also find surface subgroups in limit groups. It follows that a limit group with the same profinite completion as a free group must in fact be free, which answers a question of Remeslennikov in this case.