bluuebunny/crossref_metadata_2025 huggingface dataset:
The social organisation of metalworking in southern England during the Beaker period and Bronze Age: absence of evidence or evidence of absence?
Authors: Carey Chris , Jones Andy , Allen Michael J , Juleff Gill
Published: February 2019

This paper attempts to consider the social dimensions of metalworking during the Beaker period and Bronze Age in southern England. However, any attempt to discuss the social context of metalworking in these periods, i.e. who was working metals and where these activities occurred, is confronted with an extremely low evidence base of excavated archaeological sites where metalworking is known to have taken place. This lack of data and subsequent understanding of metalworking locations stands in stark contrast to the thousands of Beaker and Bronze Age metal artefacts housed in museum archives across Britain. These metal artefacts bear witness to the ability of people in Beaker and Bronze Age societies in Britain, and particularly southern England, to obtain, transform and use metals since the introduction of copper at c.2450 BC. Such metal artefacts have been subject to detailed analytical programmes, which have revealed information on the supply and recycling of metals. Likewise, there have also been significant advances in our understanding of the prehistoric mining of metals across the British Isles, with Beaker and Bronze Age mines identified in locations such as Ross Island (Ireland), the Great Orme (UK) and Alderley Edge (UK). Consequently, there is detailed archaeological knowledge about the two ends of the metalworking spectrum: the obtaining of the metal ores from the ground and the finished artefacts. However, the evidence for who was working metals and where is almost completely lacking. This paper discusses the archaeological evidence of the location of metalworking areas in these periods and dissects the reasons why so few have been found within archaeological excavation, with the evidence for early metallurgy likely to be slight and ambiguous, and possibly not identifiable as metalworking remains during excavation. Suggestions are made as to where such metalworking activities could have taken place in the Beaker period and Bronze Age, and what techniques can be applied to discover some of this evidence of metalworking activity, to allow access to the social dimensions of early metalworking and metalworkers.
Forwarding Control Design for Strict-Feedforward Systems
Authors: Do K. D.
Published: February 2019

This paper presents a new recursive forwarding method to design control laws that globally asymptotically stabilize strict-feedforward systems, of which Jacobian linearization at the origin might not be stabilizable. At each step, a Lyapunov function is constructed based on a solution of a linear partial differential equation (PDE) or a system of globally asymptotically stable (GAS) ordinary differential equations (ODEs). Optimal and bounded control designs are also addressed. The flexibility of the proposed design is illustrated via five examples.
Faster Positioning of One Degree-of-Freedom Mechanical Systems With Friction and Actuator Saturation
Authors: Zheng Chunhong , Su Yuxin , Mercorelli Paolo
Published: February 2019

This paper concerns with faster positioning of one degree-of-freedom (1DOF) mechanical systems with friction and actuator saturation. A very simple but quite effective saturated relay proportional-derivative (PD) control is proposed. The proposed control is conceived within the framework of nonlinear PD methodology. It is accomplished by adding a relay position error for friction compensation to the saturated PD control law. For faster transient with bounded input, a saturated nonlinear function is introduced. Lyapunov's direct method is employed to prove global asymptotic positioning. The appealing advantages of the proposed control are that it is fairly easy to construct without involvement of any modeling parameter and has the ability to avoid the actuator saturation. Numerical example and experiments demonstrate the effectiveness and improved performance of the proposed approach.
Lattice Boltzmann Simulation of Micro Gas Flows Over a Wide Range of Knudsen Numbers
Authors: Zhao Yan-Long , Wang Zhi-Ming
Published: February 2019

To characterize the microflow over a larger range of Knudsen numbers, an improved kinetic equation considering the volume diffusion effect for nonideal gases was presented based on Klimontovich's kinetic equation and Enskog equation-based lattice Boltzmann Bhatnagar–Gross–Krook (LBGK) model. Then, with the modified effective viscosity and the second-order slip boundary condition, a series of numerical simulations of gas flows with different mean Knudsen numbers were carried out based on the proposed model. Compared with the solutions of Navier–Stokes equations, Navier–Stokes equations with different slip boundary conditions, bivelocity hydrodynetics, and experimental data, we found that the present model can be valid up to a Knudsen number of 30. It is also shown that the present model furnishes a better solution in the transitional flow regime (0.1 < Kn < 10). The results not only illustrate that the present model could offer a satisfactory solution to a wider range of mean Knudsen number, but also show the importance of the compressibility and surface-dominated effects in micro gas flows. The improved model provides a promising tool for handling the micro gas flows with complex geometries and boundaries.
Studies on the Stress-Strain Relationship Bovine Cortical Bone Based on Ramberg–Osgood Equation
Authors: Sharma N. K. , Sarker M. D. , Naghieh Saman , Chen Daniel X. B.
Published: February 2019

Bone is a complex material that exhibits an amount of plasticity before bone fracture takes place, where the nonlinear relationship between stress and strain is of importance to understand the mechanism behind the fracture. This brief presents our study on the examination of the stress–strain relationship of bovine femoral cortical bone and the relationship representation by employing the Ramberg–Osgood (R–O) equation. Samples were taken and prepared from different locations (upper, middle, and lower) of bone diaphysis and were then subjected to the uniaxial tensile tests under longitudinal and transverse loading conditions, respectively. The stress–strain curves obtained from tests were analyzed via linear regression analysis based on the R–O equation. Our results illustrated that the R–O equation is appropriate to describe the nonlinear stress–strain behavior of cortical bone, while the values of equation parameters vary with the sample locations (upper, middle, and lower) and loading conditions (longitudinal and transverse).
Fabrication and characterization of a microfluidic flow cytometer for the advanced undergraduate laboratory
Authors: Gorelik Daniel , Alam Faiyza , Milstein Joshua N. , Piunno Paul A. E.
Published: February 2019

Microfluidic devices can be used to explore a vast range of phenomena in biophysics and soft-matter physics. While the popularity of these devices is in part driven by the ease of soft-lithography, most research labs still depend upon expensive, clean-room fabrication of photoresist molds, which can make this technique inaccessible to the undergraduate laboratory. However, there are much simpler, if coarser, approaches to designing molds that are capable of producing surprisingly complicated devices. Here, we detail the fabrication and characterization of a microfluidic device for flow cytometry or particle sorting on a chip. Our device is a layered polydimethylsiloxane chip that uses a series of Quake valves to sort. The molds were fabricated on equipment accessible to most undergraduate labs. The techniques and physics we discuss in this manuscript can be employed to create an almost endless variety of devices for learning about complex fluid mechanics, mesoscopic, soft-matter, and biological physics.
From measuring electron charge to exploring particle-wave duality: A new didactic experimental approach
Authors: Salançon Evelyne , Degiovanni Alain , Lapena Laurent , Morin Roger
Published: February 2019

This paper points out the strong didactic potential of an experiment originally intended for electron source research. Using a dual stage micro-channel plate in a low-energy electron point projection microscope, electrons are spatially detected one by one. Field electron emission affords wide-ranging intensity, enabling the electron charge to be determined by comparing counting and analog measurements. The same setup is used to illustrate the buildup of an interference pattern from separate low-energy electron detection, thereby enabling the Planck constant to be determined. Both granular and continuous signals are directly observable in this educational approach.
The power of the pen (and water bottle) in estimating the physics of the solar eclipse
Authors: Smith Ryan P.
Published: February 2019

I estimated the time for the moon to completely transit the disk of the sun during a solar eclipse using no tools beyond a water bottle with calibrated markings and a ball-point pen and no facts beyond everyday common knowledge. A remarkable agreement with the observation of 0.4% indicates that this strategy is successful at estimating the relative motion of the sun and moon as witnessed from the earth.
Simple analytic expressions of Fresnel diffraction patterns at a straight strip and slit for Gaussian wave illumination
Authors: Wichtowski M.
Published: February 2019

Diffraction of light on an opaque thin strip and a slit is considered, providing simple analytic formulas describing Fresnel diffraction patterns for Gaussian-beam illumination. The presented equations provide a simple way to carry out diffraction simulations. Evolution of the intensity distribution of a scattered wave through a rectilinear strip from the near to far field is also shown.
Unusual broadening of wave packets on lattices
Authors: Schönhammer K.
Published: February 2019

The broadening of one-dimensional Gaussian wave packets is presented in all textbooks on quantum mechanics. It is used as an example to elucidate Heisenberg's uncertainty relation. The behaviour on a lattice is drastically different if the amplitude and/or phase of the wave packet varies on the scale of the lattice constant. Important examples are very narrow wavepackets or wavepackets with an average velocity comparable to the maximum velocity on the lattice. The analytical and numerical results for the time dependence of wave packets on a one-dimensional lattice are presented.
Source levels of humpback whales decrease with frequency suggesting an air-filled resonator is used in sound production
Authors: Girola Elisa , Noad Michael J. , Dunlop Rebecca A. , Cato Douglas H.
Published: February 2019

Source level and frequency are important in determining how far an acoustic signal can travel. However, in some species these sound characteristics have been found to be biomechanically linked, and therefore cannot be modified independently to achieve optimal transmission. This study investigates the variability in source levels and their relationship with frequency in the songs of humpback whales (Megaptera novaeangliae). Songs were recorded off eastern Australia using a fixed hydrophone array deployed on the whales' migratory corridor. Singing whales were acoustically tracked. An empirical, frequency-dependent model was used to estimate transmission loss. Source levels and frequency were measured for 2408 song units from 19 singers. Source levels varied from 138 to 187 dB re 1 μPa at 1 m (root mean squared), while peak frequency ranged between 52 and 3877 Hz. Much of the variability in source levels was accounted for by differences between the unit types, with mean source levels for each unit type varying by up to 17 dB. Source levels were negatively correlated with peak frequency and decreased by 2.3 dB per octave. The negative correlation between source levels and frequency is consistent with the presence of an air-filled resonator in the whales' sound production system.
NDM Metallo-β-Lactamases and Their Bacterial Producers in Health Care Settings
Authors: Wu Wenjing , Feng Yu , Tang Guangmin , Qiao Fu , McNally Alan , Zong Zhiyong
Published: February 2019

New Delhi metallo-β-lactamase (NDM) is a metallo-β-lactamase able to hydrolyze almost all β-lactams. Twenty-four NDM variants have been identified in >60 species of 11 bacterial families, and several variants have enhanced carbapenemase activity.
Unsupervised Learning Approach for Comparing Multiple Transposon Insertion Sequencing Studies
Authors: Hubbard Troy P. , D’Gama Jonathan D. , Billings Gabriel , Davis Brigid M. , Waldor Matthew K.
Published: February 2019

Forward genetic screens are powerful tools for functional genomics. The comparison of similar forward genetic screens performed in different organisms enables the identification of genes with similar or different phenotypes across organisms. Transposon insertion sequencing is a widely used method for conducting genome-scale forward genetic screens in bacteria, yet few bioinformatic approaches have been developed to compare the results of screen replicates and different screens conducted across species or strains. Here, we used principal-component analysis (PCA) and hierarchical clustering, two unsupervised learning approaches, to analyze the relatedness of multiple
in vivo
screens of pathogenic vibrios. This analytic framework reveals both shared pan-vibrio requirements for intestinal colonization and strain-specific dependencies. Our findings suggest that PCA-based analytics will be a straightforward widely applicable approach for comparing diverse transposon insertion sequencing screens.
Antibody Biomarkers Associated with Sterile Protection Induced by Controlled Human Malaria Infection under Chloroquine Prophylaxis
Authors: Obiero Joshua M. , Campo Joseph J. , Scholzen Anja , Randall Arlo , Bijker Else M. , Roestenberg Meta , Hermsen Cornelus C. , Teng Andy , Jain Aarti , Davies D. Huw , Sauerwein Robert W. , Felgner Philip L.
Published: February 2019

Infection by
Plasmodium
parasites has been a major cause of mortality and morbidity in humans for thousands of years. Despite the considerable reduction of deaths, according to the WHO, over 5 billion people are still at risk, with about 216 million worldwide cases occurring in 2016. More compelling, 15 countries in sub-Saharan Africa bore 80% of the worldwide malaria burden. Complete eradication has been challenging, and the development of an affordable and effective vaccine will go a long way in achieving elimination. However, identifying vaccine candidate targets has been difficult. In the present study, we use a highly effective immunization protocol that confers long-lasting sterile immunity in combination with a whole
P. falciparum
proteome microarray to identify antibody responses associated with protection. This study characterizes a novel antibody profile associated with sterile protective immunity and trimodal humoral responses that sheds light on the possible mechanism of CPS-induced immunity against
P. falciparum
parasites.
Factors influencing suicide risk assessment clinical practice: protocol for a scoping review
Authors: Sequeira Lydia , Strudwick Gillian , Bailey Sharon M , De Luca Vincenzo , Wiljer David , Strauss John
Published: February 2019

Introduction

Every year, suicide accounts for nearly 800 000 deaths worldwide. Appropriate risk assessment and intervention are imperative since evidence demonstrates that a large proportion of those who die by suicide visit health professionals prior to their death. Much previous research has focused on identifying patient-level risk factors that can improve the risk assessment process through scales and algorithms. However, the best practice guidelines emphasise the importance of clinical interviews and prioritise the clinician’s final judgement. The purpose of this review is to (1) understand the clinician and organisational level barriers and facilitators that influence a clinician’s assessment of suicide risk, (2) identify the types of biases that exist within this process and (3) list any evidence-based training protocols and educational initiatives to aid (or support) clinicians with this process.

Methods and analysis

This scoping review protocol uses the Arksey and O’Malley framework, and Preferred Reporting Items for Systematic Reviews and Meta-Analyses reporting guidelines for scoping reviews. Literature will be identified using a multidatabase search strategy developed in consultation with a medical librarian. The proposed screening process consists of a title and abstract scan, followed by a full-text review by two reviewers to determine the eligibility of articles. Studies outlining any factors that affect a clinician’s suicide risk assessment process, ranging from individual experience and behaviours to organisational level influences, will be included. A tabular synthesis of the general study details will be provided, as well as a narrative synthesis of the extracted data, organised into themes using the Situated Clinical Decision-Making framework.

Ethics and dissemination

Ethical approval is not required for this review. Results will be translated into educational materials and presentations for dissemination to appropriate knowledge users. Knowledge outputs will also include academic presentations at relevant conferences, and a published, peer-reviewed journal article.
‘Golden Patient’: A quality improvement project aiming to improve trauma theatre efficiency in the Royal Gwent Hospital
Authors: Key Thomas , Reid Gavin , Vannet Nicola , Lloyd John , Burckett-St. Laurent David
Published: February 2019

The efficiency of trauma lists when compared with elective orthopaedic lists is a frustration of many orthopaedic departments. At the Royal Gwent Hospital, late start times affecting total operating capacity of the trauma list were recognised as a problem within the department. The design team aimed to improve the start time of the list with the introduction of the ‘golden patient’ initiative. A protocol was agreed between the orthopaedic, anaesthetic and theatre staff where a ‘golden patient’ was selected for preoperative anaesthetic assessment by 14:00 the day before surgery and sent for at 08:15 as the first case on the trauma list. Baseline data was collected over a month. Two Plan-Do-Study-Act (PDSA) cycles were completed, one on the month the ‘golden patient’ initiative was implemented and one 4 months after the change. All data was collected from the Operating Room Management Information Service theatre system for the trauma theatre at the Royal Gwent Hospital. Results demonstrated significant improvement in patient arrival time in the theatre suite; PDSA1 by 33 min (p≤0.001) and PDSA2 by 29 min (p≤0.001) and an earlier start of the first procedure; PDSA1 by 19 min (p=0.018) and PDSA2 by 26 min (p≤0.001). There was also increased mean operating time per list (PDSA1 +16 min and PDSA2 +33 min), increased total case number (PDSA1 +20 cases and PDSA2 +36 cases) and reduced cancellations (PDSA1 −2 cases and PDSA −5 cases) compared with our baseline data. We demonstrated that the introduction of a ‘golden patient’ to the trauma theatre list improved the start time and overall operating capacity for the trauma list. Continuing this project, we plan to introduce assessment of all patients with fractured neck of femur in a similar way to the ‘golden patient’ to continue improving trauma theatre efficiency and reduce case cancellations.
Sarcoidosis in the UK: insights from British Thoracic Society registry data
Authors: Thillai Muhunthan , Chang William , Chaudhuri Nazia , Forrest Ian , Ho Ling-Pei , Lines Sarah , Maher Toby M , Spencer Lisa G , Spiteri Monica , Coker Robina
Published: February 2019

Introduction

The British Thoracic Society Sarcoidosis Registry allows physicians to record clinical data after gaining written consent from patients. The registry’s aim is to phenotype sarcoidosis in the UK.

Methods

Between February 2013 and July 2017, demographic details for 308 patients (with complete clinical data for 205 patients) presenting to 24 UK hospitals were recorded. This data was analysed to detail methods of presentation, diagnosis and management.

Results

Fatigue was a significant complaint, affecting 30% of all patients. The most prevalent CT findings were nodules (in 77% of cases) with traction bronchiectasis (11%), distortion (9%) and ground glass (5%) less prominent. Of 205 patients with complete clinical data, only 64% had a diagnostic tissue biopsy. 35% of all patients underwent endobronchial ultrasound-guided transbronchial needle aspirate (EBUS-TBNA) with 15% having a transbronchial biopsy. Use of EBUS-TBNA showed an overall increase over time, from 28% of all patients in 2013 to 43% in 2016. The most common steroid sparing treatment was methotrexate, but 42% of patients were not initiated on any pharmacological treatment at the time of inclusion.

Discussion

Fatigue was common and has shown association with poor quality of life. We therefore suggest using a fatigue questionnaire as part of all new patient assessments. It may be that EBUS-TBNA should be reserved for cases of stage I or II disease where there is a reported higher yield than using transbronchial biopsy alone. Bronchoalveolar lavage was not widely used in our data, but it is generally a safe and useful adjunct and should be used more widely.
World trauma education: hemorrhage control training for healthcare providers in India
Authors: Smith Lindsay Andrea , Caughey Sarah , Liu Susan , Villegas Cassandra , Kilaru Mohan , Gupta Aakanksha , Winchell Robert J , Narayan Mayur
Published: February 2019

Background

Hemorrhage remains a major cause of death around the world. Eighty percent of trauma patients in India do not receive medical care within the first hour. The etiology of these poor outcomes is multifactorial. We describe findings from the first Stop the Bleed (StB) course recently offered to a group of medical providers in southern India.

Methods

A cross-sectional survey of 101 participants who attended StB trainings in India was performed. Pre-training and post-training questionnaires were collected from each participant. In total, 88 healthcare providers’ responses were analyzed. Three bleeding control skills were presented: wound compression, wound packing, and tourniquet application.

Results

Among participants, only 23.9% had received prior bleeding control training. Participants who reported feeling ‘extremely confident’ responding to an emergency medical situation rose from 68.2% prior to StB training to 94.3% post-training. Regarding hemorrhage control abilities, 37.5% felt extremely confident before the training, compared with 95.5% after the training. For wound packing and tourniquet application, 44.3% and 53.4%, respectively, felt extremely confident pre-training, followed by 97.7% for both skills post-training. Importantly, 90.9% of StB trainees felt comfortable teaching newly acquired hemorrhage control skills. A significant majority of participants said that confidence in their wound packing and tourniquet skills would improve with more realistic mannequins.

Conclusion

To our knowledge, this is the first StB training in India. Disparities in access to care, long transport times, and insufficient numbers of prehospital personnel contribute to its significant trauma burden. Dissemination of these critical life-saving skills into this region and the resulting civilian interventions will increase the number of trauma patients who survive long enough to reach a trauma center. Additionally, considerations should be given to translating the course into local languages to increase program reach.

Level of Evidence

Level IV.
Trauma ICU Prevalence Project: the diversity of surgical critical care
Authors: Michetti Christopher P , Fakhry Samir M , Brasel Karen , Martin Niels D , Teicher Erik J , Newcomb Anna
Published: February 2019

Background

Surgical critical care is crucial to the care of trauma and surgical patients. This study was designed to provide a contemporary assessment of patient types, injuries, and conditions in intensive care units (ICU) caring for trauma patients.

Methods

This was a multicenter prevalence study of the American Association for the Surgery of Trauma; data were collected on all patients present in participating centers’ trauma ICU (TICU) on November 2, 2017 and April 10, 2018.

Results

Forty-nine centers submitted data on 1416 patients. Median age was 58 years (IQR 41–70). Patient types included trauma (n=665, 46.9%), non-trauma surgical (n=536, 37.8%), medical (n=204, 14.4% overall), or unspecified (n=11). Surgical intensivists managed 73.1% of patients. Of ICU-specific diagnoses, 57% were pulmonary related. Multiple high-intensity diagnoses were represented (septic shock, 10.2%; multiple organ failure, 5.58%; adult respiratory distress syndrome, 4.38%). Hemorrhagic shock was seen in 11.6% of trauma patients and 6.55% of all patients. The most common traumatic injuries were rib fractures (41.6%), brain (38.8%), hemothorax/pneumothorax (30.8%), and facial fractures (23.7%). Forty-four percent were on mechanical ventilation, and 17.6% had a tracheostomy. One-third (33%) had an infection, and over half (54.3%) were on antibiotics. Operations were performed in 70.2%, with 23.7% having abdominal surgery. At 30 days, 5.4% were still in the ICU. Median ICU length of stay was 9 days (IQR 4–20). 30-day mortality was 11.2%.

Conclusions

Patient acuity in TICUs in the USA is very high, as is the breadth of pathology and the interventions provided. Non-trauma patients constitute a significant proportion of TICU care. Further assessment of the global predictors of outcome is needed to inform the education, research, clinical practice, and staffing of surgical critical care providers.

Level of evidence

IV, prospective observational study.
Acute cardiometabolic effects of interrupting sitting with resistance exercise breaks
Authors: Kowalsky Robert J. , Jakicic John M. , Hergenroeder Andrea , Rogers Renee J. , Gibbs Bethany Barone
Published: February 2019

Interrupting prolonged sitting with light activity breaks, such as short walks, improves cardiometabolic outcomes, yet less is known about the impact of resistance exercise breaks. This study examined the effects of hourly, guidelines-based simple resistance exercise breaks on acute cardiometabolic health outcomes over a simulated work period. Fourteen adults (age: 53.4 ± 9.5 years, body mass index: 30.9 ± 4.8 kg/m2) completed 2 randomized 4-h conditions: prolonged sitting (SIT) and hourly resistance exercise breaks (REX). Glucose, triglycerides, blood pressure, and heart rate were measured at baseline and then hourly. Pulse wave velocity (PWV) was measured before and after each condition. Linear mixed models evaluated overall condition effects and differences at each hour. Cohen’s d estimated magnitude of effects. Four-hour glucose area under the curve (AUC) did not differ by condition (REX vs. SIT: β = –0.35 mmol/L, p = 0.278, d = 0.51). However, an attenuation of postprandial glucose at 1 h (β = –0.69 mg/dL, p = 0.004, d = 1.02) in REX compared with SIT was observed. Triglyceride AUC, mean blood pressure, and PWV did not differ significantly between REX and SIT overall or any time point (all p > 0.05). Heart rate was higher across the experimental period in REX versus SIT (β = 3.3 bpm, p < 0.001, d = 0.35) and individual time points (β ≥ 3.2 bpm, p ≤ 0.044, d ≥ 0.34). Resistance exercise breaks can potentially improve 1-h postprandial glucose, but may not acutely benefit other cardiometabolic outcomes. Future studies employing guidelines-based resistance exercises to interrupt prolonged sitting with a larger sample and longer follow-up are warranted.
Soil structure dynamics in annual croplands under controlled traffic management
Authors: Guenette Kris G. , Hernandez-Ramirez Guillermo , Gamache Peter , Andreiuk Roger , Fausak Lewis
Published: February 2019

Soil samples were collected from commercial agriculture sites within western Canada that were subjected to compaction from farm equipment in both conventional (imposed) traffic and controlled traffic regimes. Soil characteristics such as bulk density, pore volume fractions, and unsaturated hydraulic conductivity were compared with soil physical quality parameters, such as S-index and mass fractal aggregation between trafficked and untrafficked field areas. Our results showed that untrafficked soil characteristics displayed substantial improvements over those exposed to equipment compaction. Untrafficked soils in the controlled traffic regime exhibited total porosity improvements up to 15% in more than half of the study sites. In addition, spatial reductions of equipment compaction increased the volume of soil pore diameters associated with preferential water transmission from 40% to 180%. Changes in these soil characteristics within untrafficked soils correlated well with enhancements in the soil structure metrics, as improvements to the S-index were coupled with evidence of hierarchical aggregation. Irrespective of the positive changes to soil structure, significant increases in crop yield were rarely observed in favor of a controlled traffic regime. Our results suggest that the integration of controlled traffic farming into management systems may take several years for the benefits to soil physical quality to translate into observable improvements in crop yield.
Soil health indicators after 21 yr of no-tillage in south coastal British Columbia
Authors: Thomas Ben W. , Hunt Derek , Bittman Shabtai , Hannam Kirsten D. , Messiga Aimé J. , Haak Dennis , Sharifi Mehdi , Hao Xiying
Published: February 2019

The lower Fraser Valley is one of the most intensively cropped regions in Canada. Yet, how soil health indicators respond to long-term intensive agricultural management is poorly documented in this region. Thus, we evaluated a suite of soil health indicators in response to 21 growing seasons of continuous silage corn (Zea mays L.) under conventional tillage or no-tillage (0–20 cm soil layer). Wet aggregate stability, available water capacity, active carbon (permanganate oxidizable, POXC), and extractable potassium and extractable magnesium were significantly greater with no-till than conventional tillage, whereas 8 of 13 indicators were similar. Soil health indicators responded more favourably to no-till than conventional tillage.
A multi-region study reveals high overwinter loss of fall-applied reactive nitrogen in cold and frozen soils
Authors: Chantigny Martin H. , Bittman Shabtai , Larney Francis J. , Lapen David , Hunt Derek E. , Goyer Claudia , Angers Denis A.
Published: February 2019

In cold agricultural regions, animal manure and synthetic fertilizers may be applied in the fall for convenience. However, the fate of applied nitrogen (N) is unclear and may differ depending on N source and interannual and regional variations in winter conditions. A multi-region study using 15N-labelled reactive N (NH4-15N) applied in the fall with pig slurry, dairy cattle slurry, and ammonium sulfate was carried out under a range of climatic conditions. Nitrification and immobilization of applied NH4-N occurred throughout the winter period at all sites. Transformation and losses were slower and less at the sites where significant soil freezing occurred than at the site where soil rarely froze, highlighting the repressive effect of frost. Nevertheless, losses were similar among sites with significant freezing despite marked differences in duration and extent of freezing. This suggests that soil microbes were adapted to prevailing winter conditions at each site and able to use and transform fall-applied N throughout the winter period. Overall, 47%–94% of fall-applied NH4-N was lost from the top 30 cm of soil before seeding in the next spring. Losses were generally greater with synthetic fertilizer than manures, likely because fresh carbon added with manures stimulated immobilization of NH4-N. This multi-region assessment indicates that reactive N applied in the fall has high vulnerability to loss in cold and frozen soils, and strategies for improving N retention over the winter are required even in areas where prolonged freezing occurs.
Fabrication of flower-like TiO2 on Bucky paper with enhanced photocatalytic activity
Authors: Zhang Dongmei , Pan Lujun , Li Chengwei , Xia Lichen , Hu Yunping , Bin Yuezhen , Gao Wei
Published: February 2019

The difficulty of recycling and low photocatalytic efficiency in the visible light significantly limit the use of nano-TiO2 in water pollution control. In this work, Bucky papers (BPs), which play a vital role for adsorption of pollutants and transfer of electrons, are introduced as substrates to fabricate and anchor TiO2 nanorods by a facile hydrothermal method. The photocatalytic properties of the TiO2 and BP composites (TiO2@BP) are studied by photodegrading methylene blue in water solutions. It is found that TiO2@BP possesses four times photocatalytic efficiency for methylene blue of TiO2@Si under ultraviolet light irradiation and 10 times under visible light irradiation. This is considered to be attributed to the synergic effect of TiO2@BP system and surface defects of TiO2 nanorods. The TiO2@BP also shows a stable photocatalytic property even after five cyclic photocatalytic degradation. This study indicates that TiO2@BP is a promising candidate for photocatalytic applications, which provides a reference for further research on synthesis of reusable photocatalysts with higher efficiency.
Phonon heat transport properties of graphene based on molecular dynamics simulations and lattice dynamics
Authors: Hui Zhixin , Chang Yufeng
Published: February 2019

To choose an ideal method to study the phonon properties of graphene, the results of thermal conductivity (TC) of graphene computed using the equilibrium molecular dynamics (EMD), reverse nonequilibrium molecular dynamics (RNEMD) and direct nonequilibrium molecular dynamics (DNEMD) with Tersoff potential are compared, and we find that all of them are very close to each other. While two of them have been compared in the past, there is a lack of comparison of the three methods. Eventually, we choose the Green–Kubo method to study the temperature dependence of TC in graphene and find that the [Formula: see text] diverges with the system temperature T as [Formula: see text]T[Formula: see text] with [Formula: see text] and [Formula: see text] for the direction of armchair and zigzag, respectively, which is in reasonable agreement with the one in recent theoretical and experimental researches. To gain further insight into the TC, the phonon dispersion and the phonon density of states (PDOS), which depend on evaluating the eigenvalues and the eigenvectors of dynamical matrix, are calculated for graphene with dimensions of 30 × 30 unit cell by a combination of EMD simulations and lattice dynamics calculations.
A system of rate equations governing a two-sided optical cavity
Authors: Bracken Paul
Published: February 2019

An evolution equation is introduced which governs a two-sided optical cavity under spontaneous photon emission. This equation implies a system of rate equations for expectation values of combinations of operators relevant to the cavity. This system of equations closes with respect to these variables and it can be solved completely in closed form. Some of the properties of the solutions such as the large time behavior of the expectation values and other properties will be discussed.
Ground state binding energies and RMS radii of Λ in hypernuclei in the presence of spin-dependent potential
Authors: Armat A. , Mohammad Moosavi Nejad S.
Published: February 2019

In recent years, the physics of hypernuclei has been in progress dramatically both in experiments and theories. In this regard, there have been considerable interests in the study of [Formula: see text]-particle 1s state in hypernuclei using relativistic quantum mechanics. Many theoretical results have been obtained numerically in the relativistic frameworks. In this work, using the relativistic Dirac equation, we study the properties of [Formula: see text]-particle in the hypernuclei analytically and, specifically, we determine its binding energies of ground state in a single [Formula: see text]-hypernuclei. The [Formula: see text]-N potential is considered as a spin-dependent term and the radial dependence of potential is approximated by a Gaussian function. For a more complete analysis, we will also compute the hypernuclei mass, its wave function and the root mean square (RMS) radii of [Formula: see text] orbits in [Formula: see text]-hypernuclear system.
AN ANALYTICAL SCHEME FOR THE ANALYSIS OF MULTI-HUMP SOLITONS
Authors: NAVICKAS ZENONAS , TELKSNYS TADAS , TIMOFEJEVA INGA , RAGULSKIS MINVYDAS , MARCINKEVICIUS ROMAS
Published: February 2019

An analytical framework for the analysis of multi-hump solitons is proposed in this paper. Multi-hump solitons are defined by imposing special symmetry conditions on the classical soliton expression. Such soliton solutions have a wide range of potential applications in the field of optical communications. The proposed algebras of soliton solutions enable a new look at the propagation dynamics of complex nonlinear wave phenomena. The efficiency of the presented analytical scheme is demonstrated using a system of Riccati differential equations with diffusive and multiplicative coupling.
Heat and Mass Transfer in an Unsteady Second Grade Nanofluid with Viscous Heating Dissipation
Authors: Oloniiju Shina D. , Goqo Sicelo P. , Sibanda Precious
Published: February 2019

This study presents the boundary layer flow of a second grade fluid in a rotating reference frame. The model equations are solved numerically using the bivariate spectral quasi-linearization method to obtain the fluid properties. We investigate the effects of measurable quantities such as the rate of rotation, thermal diffusivity, energy dissipation, viscoelastic parameter and other material properties of the fluid on the flow. The results show that slow rotation leads to a quick decline in the thicknesses of the momentum, thermal and concentration boundary layers. There is also a region of reverse flow for fluids with high Prandtl number.
Fractional Order Derivative and Integral Computation with a Small Number of Discrete Input Values Using Grünwald–Letnikov Formula
Authors: Brzeziński Dariusz W.
Published: February 2019

High-accuracy computer approximation of fractional derivatives and integrals by applying Grünwald–Letnikov formula generally requires a large number of input values. If required amount cannot be supplied, accuracy of approximation drops drastically. In this paper, we solve a difficult problem in this scope, i.e., when input data consists only of a small number of discrete values. Furthermore, some of the values may be unusable for computational purposes. Our problem solution includes an appropriate method of input data preprocessing, an interpolation algorithm with extrapolation abilities, a central point function discretization schema, recurrent computational method of coefficients and application of Horner’s schema for the core of the Grünwald–Letnikov method: coefficients and function’s values multiplication. Numerical method presented in the paper enables to compute fractional derivatives and integrals of complicated functions with much higher accuracy than it is possible when application of the default approach to Grünwald–Letnikov method computer implementation is applied. This new method usually takes only 10% of function’s values required by the default approach for the same computations and is much less restrictive for their quality. The general novelty of the method is an efficient configuration of existing numerical methods and enhancement of their abilities by applying modern programming language — Python and arbitrary precision arithmetic for computations.
Integrable deformations, bi-Hamiltonian structures and nonintegrability of a generalized Rikitake system
Authors: Huang Kaiyin , Shi Shaoyun , Xu Zhiguo
Published: February 2019

The aim of this paper is to investigate a generalized Rikitake system from the integrability point of view. For the integrable case, we derive a family of integrable deformations of the generalized Rikitake system by altering its constants of motion, and give two classes of Hamilton–Poisson structures which implies these integrable deformations, including the generalized Rikitake system, are bi-Hamiltonian and have infinitely many Hamilton–Poisson realizations. By analyzing properties of the differential Galois groups of normal variational equations (NVEs) along certain particular solution, we show that the generalized Rikitake system is not rationally integrable in an extended Liouville sense for almost all parameter values, which is in accord with the fact that this system admits chaotic behaviors for a large range of its parameters. The non-existence of analytic first integrals are also discussed.
Delamination of Stiff Films on Pressure Sensitive Ductile Substrates
Authors: An Bingbing
Published: February 2019

Stiff thin films supported by pressure sensitive ductile solids are an ubiquitous architecture appearing in a wide range of applications. The film rupture and delamination of films are important reliability issues of such an architecture. In this study, we investigate the synergistic effects of plastic deformation of substrates and fracture properties of film/substrate interface on the delamination of films. The focus of this study is on the interplay between the debonding of the interface and the plastic deformation of substrates. Finite deformation analyses are carried out for a stiff film deposited on a soft substrate with the substrate subjected to stretching. The fracture process of film/substrate interface is represented by a cohesive zone model, and the substrate is modeled as an elastic–plastic solid with pressure sensitive and plastically dilatant plastic flow. It is found that increasing the degree of pressure sensitivity of substrate can generate large plastic deformation, promoting crack tip blunting and thereby retarding delamination of film/substrate interface. Whereas, the increase in the degree of plastic dilatancy of substrate gives rise to the limited plastic deformation and leads to poor resistance to interface delamination. The strain hardening of substrate also affects the film/substrate debonding; the substrate with weakly post-yield strain hardening behavior contributes to enhanced resistance to interface delamination. It is further identified that the fracture properties of interface play an important role in activating plastic deformation of substrates. The film/substrate interface with high stiffness, large cohesive strength and high toughness enables the substrate to undergo significant plastic deformation, which suppresses the film/substrate delamination.
30th ACM international conference on hypertext and social media
Authors: atzenbeck Claus , Rubart Jessica , Millard David
Published: February 2019

The ACM Hypertext conference is a premium venue for high quality peer-reviewed research on hypertext theory, systems and applications. It is concerned with all aspects of modern hypertext research including social media, semantic web, dynamic and computed hypertext and hypermedia as well as narrative systems and applications.
Distributed Protocols for Leader Election
Authors: Abraham Ittai , Dolev Danny , Halpern Joseph Y.
Published: February 2019

We do a game-theoretic analysis of leader election, under the assumption that each agent prefers to have some leader than no leader at all. We show that it is possible to obtain a
fair
Nash equilibrium, where each agent has an equal probability of being elected leader, in a completely connected network, in a bidirectional ring, and a unidirectional ring, in the synchronous setting. In the asynchronous setting, Nash equilibrium is not quite the right solution concept. Rather, we must consider
ex post
Nash equilibrium; this means that we have a Nash equilibrium no matter what a scheduling adversary does. We show that ex post Nash equilibrium is attainable in the asynchronous setting in all the networks we consider, using a protocol with bounded running time. However, in the asynchronous setting, we require that
n
> 2. We show that we can get a fair ex post
ϵ-Nash
equilibrium if
n
=2 in the asynchronous setting under some cryptographic assumptions (specifically, the existence of a one-way functions), using a
commitment protocol
. We then generalize these results to a setting where we can have deviations by a coalition of size
k
. In this case, we can get what we call a fair
k
-resilient equilibrium in a completely connected network if
n
> 2
k
; under the same cryptographic assumptions, we can a get a
k
-resilient equilibrium in a completely connected network, unidirectional ring, or bidirectional ring if
n
>
k
. Finally, we show that under minimal assumptions, not only do our protocols give a Nash equilibrium, they also give a
sequential
equilibrium, so players even play optimally off the equilibrium path.
Accelerating indefinite hypergeometric summation algorithms
Authors: Zima Eugene V.
Published: February 2019

Let K be a field of characteristic zero,
x
an independent variable,
E
the shift operator with respect to
x,
i.e.,
Ef
(
x
) =
f
(
x
+ 1) for an arbitrary
f
(
x
). Recall that a nonzero expression
F
(
x
) is called a hypergeometric term over K if there exists a rational function
r
(
x
) ∈ K(
x
) such that
F
(
x
+ 1)/
F
(
x
) =
r
(
x
). Usually
r
(
x
) is called the rational
certificate
of
F
(
x
). The problem of indefinite hypergeometric summation (anti-differencing) is: given a hypergeometric term
F
(
x
), find a hypergeometric term
G
(
x
) which satisfies the first order linear difference equation

(
E
− 1)
G
(
x
) =
F
(
x
). (1)

If found, write Σ

x

F
(
x
) =
G
(
x
) +
c
, where
c
is an arbitrary constant.
A fast algorithm for solving linearly recurrent sequences
Authors: Hyun Seung Gyu , Melczer Stephen , St-Pierre Catherine
Published: February 2019

We present an algorithm which computes the

D
th

term of a sequence satisfying a linear recurrence relation of order
d
over a field K in
O
(M(d̄) log(
D
) + M(
d
) log(
d
)) operations in K, where d̄ ≤
d
is the degree of the squarefree part of the annihilating polynomial of the recurrence and M is the cost of polynomial multiplication in K. This is a refinement of the previously optimal result of
O
(M(
d
) log(
D
)) operations, due to Fiduccia.
Indicator amino acid oxidation protein requirement estimate in endurance-trained men 24 h postexercise exceeds both the EAR and current athlete guidelines
Authors: Bandegan Arash , Courtney-Martin Glenda , Rafii Mahroukh , Pencharz Paul B. , Lemon Peter W. R.
Published: February 2019

Despite studies indicating increased protein requirements in strength-trained or endurance-trained (ET) individuals, the Institute of Medicine has concluded that “no additional dietary protein is suggested for healthy adults undertaking resistance or endurance exercise,” and the controversy regarding exercise effects on protein requirements continues. The objective of this study was to determine the dietary protein requirement of healthy young ET men (≥1 yr training experience) 24 h post exercise (to minimize any acute effects of the previous training session) by measuring the oxidation of ingested l-[1-13C]phenylalanine to 13CO2 in response to graded intakes of protein (indicator amino acid oxidation technique). Eight men [maximal oxygen consumption 64.1 ml·kg−1·min−1 (SD 3.7)] were each studied 24 h postexercise repeatedly with protein intakes ranging from 0.3 to 3.5 g·kg−1·day−1. Protein was fed as an amino acid mixture based on the protein pattern in egg, except for phenylalanine and tyrosine, which were maintained at constant amounts across all protein intakes. For 2 days before the study day, all participants consumed 1.6 g protein·kg−1·day−1. The estimated average requirement (EAR) for protein was determined by applying a nonlinear mixed-effects change-point regression analysis to F13CO2 (label tracer oxidation in 13CO2 breath), which identified a breakpoint in the F13CO2 in response to the graded amounts of protein. The EAR for protein and the upper 95% confidence interval were 2.1 and 2.6 g·kg−1·day−1, respectively. These data suggest that the protein EAR for ET men 24 h postexercise exceeds the Institute of Medicine EAR and established athlete guidelines by ~3.5- and 1.3-fold, respectively.