bluuebunny/crossref_metadata_2025 huggingface dataset:
Development of Measurement Methods for Vibration-Induced Stress of Small-Bore Piping
Authors: Maekawa Akira , Noda Michiyasu , Suzuki Michiaki , Suyama Takeshi , Fujita Katsuhisa
Published: April 2017

The vibration-induced fatigue failure of small-bore piping is one of the common causes of failure trouble at nuclear power plants (NPPs). Therefore, the purpose of this study is to develop the measurement methods of vibration-induced stress for the screening to prevent from fatigue failure mechanism of small-bore piping. First, a measurement method using a single-mass model was introduced, and then, a measurement method using a two-mass model developed as an improved calculation model was proposed. These two kinds of models were validated by vibration tests using mock-up with small-bore branch piping. The results showed that the single-mass model could be used as the coarse screening. Additionally, the two-mass model was found to be suitable to the fine screening due to more accurate measurement of vibration-induced stress. Next, for small-bore piping with typical pattern configurations consisting of several masses and supports, the model considering the supports and the center of gravity being out of pipe centerline was developed and put into practical use. Finally, for the more complex small-bore piping with general piping configurations consisting of many bends, branches, or joints, the method based on the finite element analysis and using the measured values was developed. In the developed method, the differences between the natural frequency and the response acceleration obtained by the measurement and those values calculated using the analysis model are optimized to be enough small, and then, the vibration-induced stress is estimated by superposing the vibration modes of the small-bore piping with the static deformation representing the main piping vibration. In this study, the usability of the developed method was confirmed by the comparison with the numerical results without the measurement error, which were assumed to be the true values. The peak stress induced by vibration frequently occurs at the filet weld part between the small-bore piping and the main piping. The developed methods can be used for various weld geometries although the measurement method using strain gauges cannot be used for such weld parts. The failure possibility by vibration-induced fatigue can be evaluated by comparing the nominal stress measured by the methods in this study with the fatigue threshold stress divided by the stress concentration factor appropriate for the weld geometry.
Experimental Study on Cavitation of a Liquid Lithium Jet for International Fusion Materials Irradiation Facility
Authors: Kondo Hiroo , Kanemura Takuji , Furukawa Tomohiro , Hirakawa Yasushi , Wakai Eiichi , Knaster Juan
Published: April 2017

A liquid Li jet flowing at 15 m/s under a high vacuum of 10−3 Pa is intended to serve as a beam target (Li target) in the planned International Fusion Materials Irradiation Facility (IFMIF). The engineering validation and engineering design activities (EVEDA) for the IFMIF are being implemented under the broader approach (BA) agreement. As a major activity of the Li target facility, the EVEDA Li test loop (ELTL) was constructed by the Japan Atomic Energy Agency. A stable Li target under the IFMIF conditions (Li temperature: 523.15 K, velocity: 15 m/s, and vacuum pressure: 10−3 Pa) was demonstrated using ELTL. This study focuses on a cavitationlike acoustic noise detected in a downstream conduit where the Li target flowed under vacuum conditions. This noise was investigated using acoustic-emission (AE) sensors installed at eight locations via acoustic wave guides. The sound intensity of the acoustic noise was examined against the cavitation number of the Li target. In addition, two types of frequency analysis, namely, fast Fourier transform (FFT) and continuous wavelet transform (CWT), were performed to characterize the acoustic noise. Owing to the acoustic noise's intermittency, high frequency, and the dependence on cavitation number, we conclude that this acoustic noise is generated when cavitation bubbles collapse and/or the structural material of the pipe is cracked because of the collapse of cavitation bubbles (cavitation pitting). The location of the cavitation was fundamental for presuming the mechanism. In this study, the propagation of acoustic waves among AE sensors placed at three locations was used to localize the cavitation and a method to determine the location of cavitation was formulated. As a result, we found that cavitation occurred only in a narrow area where the Li target impinged on the downstream conduit; therefore, we concluded that this cavitation was induced by the impingement. The design of the downstream conduit of the IFMIF Li target facility should be tackled in future based on information obtained in this study.
A Special Hybrid Projective Synchronization in Symmetric Chaotic System With Unknown Parameter
Authors: Liu Hong-juan , Yu Hai , Zhu Zhi-liang
Published: April 2017

A novel synchronization scheme called special hybrid projective synchronization (SHPS), in which different state variables can synchronize up to same positive or negative scaling factors, is proposed in this paper. For all the symmetric chaotic systems, research results demonstrate that the SHPS can be realized with a single-term linear controller. Taking unified chaotic system with unknown parameter as an example, based on Lyapunov stability theory, some sufficient conditions and a parameter update law are derived for the implementation of SPHS, which are verified by some corresponding numerical simulations.
Bottom-up construction of a superstructure in a porous uranium-organic crystal
Authors: Li Peng , Vermeulen Nicolaas A. , Malliakas Christos D. , Gómez-Gualdrón Diego A. , Howarth Ashlee J. , Mehdi B. Layla , Dohnalkova Alice , Browning Nigel D. , O’Keeffe Michael , Farha Omar K.
Published: April 2017

Intricacy anchored by uranium

Metal-organic frameworks generally have one level of assembly complexity: Organic linkers join inorganic nodes in a repeating lattice. Li
et al.
created a structure composed of cuboctahedra, assembled from uranium cations and organic linkers, that shared triangular faces to form prisms. These structures formed cages, which in turn joined to make tetrahedra that assembled with a diamond-lattice topology. This hierarchical open structure generated a huge unit cell with more than 800 nodes and linkers, containing internal cavities with diameters of 5 and 6 nm.

Science
, this issue p.
624
Draft Genome Sequence of Acinetobacter johnsonii C6, an Environmental Isolate Engaging in Interspecific Metabolic Interactions
Authors: Kaas Rolf Sommer , Mordhorst Hanne , Leekitcharoenphon Pimlapas , Dyring Jensen Jacob , Haagensen Janus A. J. , Molin Søren , Pamp Sünje Johanna
Published: April 2017

Acinetobacter johnsonii
C6 originates from creosote-polluted groundwater and performs ecological and evolutionary interactions with
Pseudomonas putida
in biofilms. The draft genome of
A. johnsonii
C6 is 3.7 Mbp and was shaped by mobile genetic elements. It reveals genes facilitating the biodegradation of aromatic hydrocarbons and resistance to antimicrobials and metals.
Complete and Assembled Genome Sequence of Lactobacillus plantarum RI-113 Isolated from Salami
Authors: Inglin Raffael C. , Meile Leo , Klumpp Jochen , Stevens Marc J. A.
Published: April 2017

We present here the complete genome sequence of
Lactobacillus plantarum
RI-113, a strain isolated from salami, which was determined using single-molecule real-time sequencing.
Draft Nuclear Genome Sequence of the Liquid Hydrocarbon–Accumulating Green Microalga
Botryococcus braunii
Race B (Showa)
Authors: Browne Daniel R. , Jenkins Jerry , Schmutz Jeremy , Shu Shengqiang , Barry Kerrie , Grimwood Jane , Chiniquy Jennifer , Sharma Aditi , Niehaus Thomas D. , Weiss Taylor L. , Koppisch Andrew T. , Fox David T. , Dhungana Suraj , Okada Shigeru , Chappell Joe , Devarenne Timothy P.
Published: April 2017

Botryococcus braunii
has long been known as a prodigious producer of liquid hydrocarbon oils that can be converted into combustion engine fuels. This draft genome for the B race of
B. braunii
will allow researchers to unravel important hydrocarbon biosynthetic pathways and identify possible regulatory networks controlling this unusual metabolism.
Complete Genome Sequence of Pseudomonas protegens H78, a Plant Growth–Promoting Rhizobacterium
Authors: Huang Xianqing , Wang Zheng , Liu Yujie , Zhang Xuehong
Published: April 2017

The plant growth–promoting rhizobacterium
Pseudomonas protegens
H78, which was isolated from the rhizosphere of oilseed rape in Shanghai, can produce a large array of antibiotics with a broad spectrum of activities. Here, we report the annotated complete genome sequence of
P. protegens
H78.
Complete Genome Characterization of Chinese Porcine Deltacoronavirus Strain CHN/Tianjin/2016
Authors: Zhao Feng , Sun Ying , Qian Bingxu , Zhang Xiaorong , Wu Yantao
Published: April 2017

As we all know, porcine deltacoronavirus was first detected in Hong Kong, China. Here, we report the complete genome sequence of the Chinese porcine deltacoronavirus strain CHN/Tianjin/2016, which was collected and amplified from clinical fecal samples in March of 2016.
Draft Genome Sequences of Two Hydrogenogenic Carboxydotrophic Bacteria,
Carboxydocella
sp. Strains JDF658 and ULO1, Isolated from Two Distinct Volcanic Fronts in Japan
Authors: Fukuyama Yuto , Oguro Tatsuki , Omae Kimiho , Yoneda Yasuko , Yoshida Takashi , Sako Yoshihiko
Published: April 2017

Hydrogenogenic carboxydotrophs may provide hydrogen as primary energy for the microbial community via carbon monoxide oxidation. To investigate the genetics of carbon monoxide metabolism, we report here the draft genome sequences of the hydrogenogenic carboxydotrophs
Carboxydocella
sp. strains JDF658 (2.60 Mbp; G+C content, 49.2%) and ULO1 (2.70 Mbp; G+C content, 48.8%).
Genome Sequences of Cluster K Mycobacteriophages DrHayes, Urkel, and SamuelLPlaqson
Authors: Anders Kirk R. , Murphy Alex M. , Ettinger William F. , Kempthorne Douglas , Kittridge Charles , Kures Alex , Lundgren Sarah , Masters Jacob , Noyes Rachel , Winters Christina , Yazzolino Perry , Ziebert Kasandra , Haydock Joseph , Hayes Stephen , Garlena Rebecca A. , Russell Daniel A. , Poxleitner Marianne K. , Ettinger Ann-Scott H.
Published: April 2017

Mycobacteriophages DrHayes, Urkel, and SamuelLPlaqson were isolated from soil samples in Spokane, WA, using
Mycobacterium smegmatis
mc
2
155 grown at room temperature. The three genomes differ by only a few nucleotides, are 60,526 bp long, have 97 predicted protein-coding genes and one tRNA gene, and are members of subcluster K1.
Cell Biology of Hyphal Growth
Authors: Steinberg Gero , Peñalva Miguel A. , Riquelme Meritxell , Wösten Han A. , Harris Steven D.
Published: April 2017

Filamentous fungi are a large and ancient clade of microorganisms that occupy a broad range of ecological niches. The success of filamentous fungi is largely due to their elongate hypha, a chain of cells, separated from each other by septa. Hyphae grow by polarized exocytosis at the apex, which allows the fungus to overcome long distances and invade many substrates, including soils and host tissues. Hyphal tip growth is initiated by establishment of a growth site and the subsequent maintenance of the growth axis, with transport of growth supplies, including membranes and proteins, delivered by motors along the cytoskeleton to the hyphal apex. Among the enzymes delivered are cell wall synthases that are exocytosed for local synthesis of the extracellular cell wall. Exocytosis is opposed by endocytic uptake of soluble and membrane-bound material into the cell. The first intracellular compartment in the endocytic pathway is the early endosomes, which emerge to perform essential additional functions as spatial organizers of the hyphal cell. Individual compartments within septated hyphae can communicate with each other via septal pores, which allow passage of cytoplasm or organelles to help differentiation within the mycelium. This article introduces the reader to more detailed aspects of hyphal growth in fungi.
Mycobacterium avium
Complex Disease
Authors: Daley Charles L.
Published: April 2017

Despite the ubiqitous nature of
Mycobacterium avium
complex (MAC) organisms in the environment, relatively few of those who are infected develop disease. Thus, some degree of susceptibility due to either underlying lung disease or immunosuppression is required. The frequency of pulmonary MAC disease is increasing in many areas, and the exact reasons are unknown. Isolation of MAC from a respiratory specimen does not necessarily mean that treatment is required, as the decision to treatment requires the synthesis of clinical, radiographic, and microbiologic information as well as a weighing of the risks and benefits for the individual patient. Successful treatment requires a multipronged approach that includes antibiotics, aggressive pulmonary hygiene, and sometimes resection of the diseased lung. A combination of azithromycin, rifampin, and ethambutol administered three times weekly is recommend for nodular bronchiectatic disease, whereas the same regimen may be used for cavitary disease but administered daily and often with inclusion of a parenteral aminoglycoside. Disseminated MAC (DMAC) is almost exclusively seen in patients with late-stage AIDS and can be treated with a macrolide in combination with ethambutol, with or without rifabutin: the most important intervention in this setting is to gain HIV control with the use of potent antiretroviral therapy. Treatment outcomes for many patients with MAC disease remain suboptimal, so new drugs and treatment regimens are greatly needed. Given the high rate of reinfection after cure, one of the greatest needs is a better understanding of where infection occurs and how this can be prevented.
Aggregatibacter actinomycetemcomitanspneumonia with chest and abdominal wall involvement
Authors: Storms Iris , van den Brand Marre , Schneeberger Peter , van 't Hullenaar Nico
Published: April 2017

A 54-year-old man presented with a productive cough, chest pain, fever and weight loss. Initial analysis revealed a palpable chest wall mass and consolidation in the left lower lobe and pleural abnormalities on imaging. At that point no infectious cause or malignancy was identified. Microbiological analysis of a needle biopsy from a newly developed abdominal wall mass revealed growth ofAggregatibacter actinomycetemcomitans. The patient was successfully treated with antibiotic therapy for 1 year.Aggregatibacter actinomycetemcomitansis a Gram-negative coccobacillus and is part of the normal oral flora. It is capable of causing infections in humans including periodontitis, soft tissue abscesses and systemic invasive infections, most commonly endocarditis.
An unusually large onychomatricoma
Authors: Beirão Pedro , Pereira Patrícia , Nunes Andreia , Barreiros Hugo
Published: April 2017

Onychomatricoma is a rare benign tumour of the nail matrix first described in 1992, and since then, no more than 80 cases have been reported. Despite distinct clinical characteristics, it is frequently misdiagnosed as onychomycosis partly due to remaining an unknown entity. The authors present the case of a patient with a 30-year history of nail abnormalities with more recent growth to alarming dimensions.
Use of gabapentin in the treatment of chronic pain in an adolescent with sickle cell disease
Authors: Correia Cátia R , Soares Ana Teresa , Azurara Laura , Palaré Maria João
Published: April 2017

Vaso-occlusive crises are the most common manifestation of sickle cell disease (SCD) and the main cause of hospital admission in these patients. There is emerging evidence that vaso-occlusive pain has both nociceptive and neuropathic components. However, the treatment of SCD-related pain with neuropathic drugs has not yet been systematically studied, particularly in children. We describe a 14-year-old girl with SCD and multiple hospital admissions for pain management for severe acute vaso-occlusive pain episodes. The patient was evaluated by a multidisciplinary team of specialists which considered that the chronic, refractory pain she was experiencing for years was probably neuropathic in origin and it was decided to start oral gabapentin (300 mg/day). At 10 months follow-up, the patient reported remarkable improvement in her quality of life with a significant decrease in the number of hospital admissions (three admissions for acute vaso-occlusive pain episodes in 10 months versus the previously monthly recurrences).
Ascites in a patient with episodic angio-oedema and eosinophilia: thinking outside the box
Authors: Rigopoulou Eirini I , Ioannou Maria , Papadamou Georgia , Dalekos Georgios N
Published: April 2017

Episodic angio-oedema with eosinophilia (EAE) or Gleich’s syndrome is a rare condition characterised by recurrent episodes of oedema and eosinophilia, accompanied by urticaria, fever and weight gain. The presence of ascites has not been reported so far. We report a 21-year-old Caucasian woman who presented with marked ocular oedema and ascites. Laboratory evaluation revealed marked eosinophilia. During the last 3 months, three episodes of facial and neck oedema were reported, which resolved spontaneously over a period of 3–5 days. The diagnosis of EAE was established after exclusion of secondary causes (infections, allergic reactions, collagen diseases, neoplasms) and clonal disorders associated with marked eosinophilia. Low-dose steroids resulted in eosinophil decrease and complete resolution of symptoms, including ascites. This case highlights that ascites can be a very rare manifestation of EAE particularly if other more frequent causes of ascites have been excluded and the clinical and laboratory findings are supportive of EAE.
Why tuberculosis control programmes fail? Role of microlevel and macrolevel factors: an analysis from India.
Authors: Bhattacharya Sudip , Singh. Amarjeet
Published: April 2017

India accounts for one-fourth of the global tuberculosis (TB) burden. The National TB Program was started in 1962. Over a period of time, some lacunae such as poor case detection rate and incomplete treatment were observed. Later, the government formulated the Revised National Tuberculosis Control Program (RNTCP), which achieved a case detection rate of 70% and a cure rate of 85%. Still, the problem of relapse and defaulter cases persists. In 2014, 6% defaulter cases were reported from India. RNTCP has also focused on microlevel aspects, that is, newer diagnostics such as GenXpert, line probe assay and medicines such as bedaquiline for drug-resistant TB. Action on the macrolevel aspects, for example, social determinants, is ignored. This is natural because these are out of the purview of the health sector. This case study reflects how a resident doctor in a rural clinic of North India tried to resolve the macrolevel and microlevel issues pertaining to defaulter TB cases.
Clinical and cost-effectiveness, safety and acceptability ofcommunityintravenousantibioticservice models: CIVAS systematic review
Authors: Mitchell E D , Czoski Murray C , Meads D , Minton J , Wright J , Twiddy M
Published: April 2017

Objective

Evaluate evidence of the efficacy, safety, acceptability and cost-effectiveness of outpatient parenteral antimicrobial therapy (OPAT) models.

Design

A systematic review.

Data sources

MEDLINE, EMBASE, CINAHL, Cochrane Library, National Health Service (NHS) Economic Evaluation Database (EED), Research Papers in Economics (RePEc), Tufts Cost-Effectiveness Analysis (CEA) Registry, Health Business Elite, Health Information Management Consortium (HMIC), Web of Science Proceedings, International Pharmaceutical Abstracts, British Society for Antimicrobial Chemotherapy website. Searches were undertaken from 1993 to 2015.

Study selection

All studies, except case reports, considering adult patients or practitioners involved in the delivery of OPAT were included. Studies combining outcomes for adults and children or non-intravenous (IV) and IV antibiotic groups were excluded, as were those focused on process of delivery or clinical effectiveness of 1 antibiotic over another. Titles/abstracts were screened by 1 reviewer (20% verified). 2 authors independently screened studies for inclusion.

Results

128 studies involving >60 000 OPAT episodes were included. 22 studies (17%) did not indicate the OPAT model used; only 29 involved a comparator (23%). There was little difference in duration of OPAT treatment compared with inpatient therapy, and overall OPAT appeared to produce superior cure/improvement rates. However, when models were considered individually, outpatient delivery appeared to be less effective, and self-administration and specialist nurse delivery more effective. Drug side effects, deaths and hospital readmissions were similar to those for inpatient treatment, but there were more line-related complications. Patient satisfaction was high, with advantages seen in being able to resume daily activities and having greater freedom and control. However, most professionals perceived challenges in providing OPAT.

Conclusions

There were no systematic differences related to the impact of OPAT on treatment duration or adverse events. However, evidence of its clinical benefit compared with traditional inpatient treatment is lacking, primarily due to the dearth of good quality comparative studies. There was high patient satisfaction with OPAT use but the few studies considering practitioner acceptability highlighted organisational and logistic barriers to its delivery.
How are non-numerical prognostic statements interpreted and are they subject to positive bias?
Authors: Moyer Anne , Siess Samantha , Bhinder Sumeet
Published: April 2017

Objectives

Frank, clear communication with family members of terminally ill or incapacitated patients has important implications for well-being, satisfaction with care and sound decision-making. However, numerical prognostic statements, particularly more negative ones, have been found to be interpreted in a positively biased manner. Less precise non-numerical statements, preferred by physicians, and particularly statements using threatening terms (dying vs surviving) may be even more subject to such biases.

Methods

Participants (N=200) read non-numerical prognostic statements framed in terms of dying or surviving and indicated their interpretation of likelihood of survival.

Results

Even the most extreme statements were not interpreted to indicate 100% likelihood of surviving or dying, (eg, they will definitely survive, 92.77%). The poorness of prognoses was associated with more optimistically biased interpretations but this was not, however, affected by the wording of the prognoses in terms of dying versus surviving.

Conclusions

The findings illuminate the ways in which commonly used non-numeric language may be understood in numeric terms during prognostic discussions and provide further evidence of recipients' propensity for positive bias.
Proliferation of primary human hepatocytes and prevention of hepatitis B virus reinfection efficiently deplete nuclear cccDNA in vivo
Authors: Allweiss Lena , Volz Tassilo , Giersch Katja , Kah Janine , Raffa Giuseppina , Petersen Joerg , Lohse Ansgar W , Beninati Concetta , Pollicino Teresa , Urban Stephan , Lütgehetmann Marc , Dandri Maura
Published: April 2017

Objective

The stability of the covalently closed circular DNA (cccDNA) in nuclei of non-dividing hepatocytes represents a key determinant of HBV persistence. Contrarily, studies with animal hepadnaviruses indicated that hepatocyte turnover can reduce cccDNA loads but knowledge on the proliferative capacity of HBV-infected primary human hepatocytes (PHHs) in vivo and the fate of cccDNA in dividing PHHs is still lacking. This study aimed to determine the impact of human hepatocyte division on cccDNA stability in vivo.

Methods

PHH proliferation was triggered by serially transplanting hepatocytes from HBV-infected humanised mice into naïve recipients. Cell proliferation and virological changes were assessed by quantitative PCR, immunofluorescence and RNA in situ hybridisation. Viral integrations were analysed by gel separation and deep sequencing.

Results

PHH proliferation strongly reduced all infection markers, including cccDNA (median 2.4 log/PHH). Remarkably, cell division appeared to cause cccDNA dilution among daughter cells and intrahepatic cccDNA loss. Nevertheless, HBV survived in sporadic non-proliferating human hepatocytes, so that virological markers rebounded as hepatocyte expansion relented. This was due to reinfection of quiescent PHHs since treatment with the entry inhibitor myrcludex-B or nucleoside analogues blocked viral spread and intrahepatic cccDNA accumulation. Viral integrations were detected both in donors and recipient mice but did not appear to contribute to antigen production.

Conclusions

We demonstrate that human hepatocyte division even without involvement of cytolytic mechanisms triggers substantial cccDNA loss. This process may be fundamental to resolve self-limiting acute infection and should be considered in future therapeutic interventions along with entry inhibition strategies.
Acute presentation of autoimmune hepatitis: a multicentre study with detailed histological evaluation in a large cohort of patients
Authors: Nguyen Canh Hiep , Harada Kenichi , Ouchi Hirofumi , Sato Yasunori , Tsuneyama Koichi , Kage Masayoshi , Nakano Masayuki , Yoshizawa Kaname , Takahashi Atsushi , Abe Masanori , Kang Jong-Hon , Koike Kazuhiko , Inui Ayano , Fujisawa Tomoo , Takaki Akinobu , Arinaga-Hino Teruko , Torimura Takuji , Suzuki Yoshiyuki , Fujiwara Keiichi , Zeniya Mikio , Ohira Hiromasa , Tanaka Atsushi , Takikawa Hajime
Published: April 2017

Aims

Although liver biopsy is crucial to diagnose and guide treatment decisions, a detailed histological analysis of autoimmune hepatitis (AIH) with clinically acute presentations has not yet been performed. This study aimed to characterise the histological features and explore potential histological hallmarks to diagnose the acute presentation of AIH.

Methods

We systematically evaluated liver specimens of 87 adult patients with acute presentation of AIH retrospectively enrolled from Japanese multicentre facilities. Each histological feature was predefined by consensus based on the diagnostic criteria.

Results

Key findings were that acute presentation of AIH revealed histological features of both acute hepatitis and chronic hepatitis accompanying various degrees of fibrosis. The prominent features were lobular necrosis/inflammation (97.7%), plasma cell infiltration (96.4%), emperipolesis (89.3%), pigmented macrophages (84.5%), cobblestone appearance of hepatocytes (82.6%) and perivenular necroinflammatory activity, including centrilobular necrosis (81.4%).

Conclusions

The acute presentation of AIH represents the entire histological spectrum of acute hepatitis and chronic hepatitis with various activity grades and fibrosis stages that clinically correspond to acute-onset AIH and acute exacerbation of classic AIH, respectively. Although there are no pathognomonic features for the pathological diagnosis, the prominent presence of lobular and perivenular necroinflammatory activity, pigmented macrophages and cobblestone appearance of hepatocytes in addition to the classic AIH features, such as plasma cell infiltration and emperipolesis, are useful for the pathological diagnosis of the acute presentation of AIH.
Water tracks in the High Arctic: a hydrological network dominated by rapid subsurface flow through patterned ground
Authors: Paquette Michel , Fortier Daniel , Vincent Warwick F.
Published: April 2017

Water tracks play a major role in the headwater basin hydrology of permafrost landscapes in Alaska and Antarctica, but less is known about these features in the High Arctic. We examined the physical and hydrological properties of water tracks on Ward Hunt Island, a polar desert site in the Canadian High Arctic, to evaluate their formation process and to compare with water tracks reported elsewhere. These High Arctic water tracks flowed through soils that possessed higher near-surface organic carbon concentrations, higher water content, and coarser material than the surrounding soils. The water track morphology suggested they were initiated by a combination of sorting, differential frost heaving, and eluviation. The resultant network of soil conduits, comparable to soil pipes, dominated the hydrology of the slope. The flow of cold water through these conduits slowed down the progression of the thawing front during summer, making the active layer consistently shallower relative to adjacent soils. Water tracks on Ward Hunt Island, and in polar desert catchments with these features elsewhere in the High Arctic, strongly influence slope hydrology and active-layer properties while also affecting vegetation distribution and the quality of runoff to the downstream lake.
Arctic permafrost landscapes in transition: towards an integrated Earth system approach
Authors: Vincent Warwick F. , Lemay Mickaël , Allard Michel
Published: April 2017

Permafrost science and engineering are of vital importance for northern development and climate adaptation given that buildings, roads, and other infrastructure in many parts of the Arctic depend on permafrost stability. Permafrost also has wide-ranging effects on other features of the Arctic environment including geomorphology, biogeochemical fluxes, tundra plant and animal ecology, and the functioning of lake, river, and coastal marine ecosystems. This review presents an Earth system perspective on permafrost landscapes as an approach towards integration across disciplines. The permafrost system can be described by a three-layer conceptual model, with an upper buffer layer that contains vegetation or infrastructure. Snow and liquid water strongly affect the thermal properties and stability of these layers and their associated interfaces, resulting in critical times and places for accelerated degradation of permafrost and for exchanges of mass and heat with the hydrosphere and atmosphere. Northern permafrost landscapes are now in rapid transition as a result of climate warming and socioeconomic development, which is affecting their ability to provide geosystem and ecosystem services. The Earth system approach provides a framework for identifying linkages, thresholds, and feedbacks among system components, including human systems, and for the development of management strategies to cope with permafrost change.
Seismic and gravity constraints on the crustal architecture of the Intermontane terranes, central Yukon
Authors: Calvert Andrew J. , Hayward Nathan , Vayavur Rajesh , Colpron Maurice
Published: April 2017

In 2004, two seismic reflection lines were shot across the Mesozoic Whitehorse trough and adjacent terranes. Three-dimensional first-arrival tomographic inversion is used to constrain lithology to 800–1200 m depth, and surface structures are extrapolated into the middle crust using the coincident reflection data. In the Yukon–Tanana terrane, the metasedimentary Snowcap assemblage is characterized by velocities of 4.5–5.5 km/s, while in Quesnellia, velocities of 5.0–6.0 km/s occur at 500 m depth, and probably represent igneous rocks of the Tatchun batholith. Across the Whitehorse trough, velocities >4.0 km/s correspond to clastic rocks of the Jurassic Laberge and Triassic Lewes River groups; velocities <4.0 km/s probably present the clastic Jurassic to Cretaceous Tantalus Formation. Several near-surface units with velocities of 2.0–3.0 km/s are identified; some correlate well with volcanic rocks of the Upper Cretaceous Carmacks Group, but others could be attributable to alluvial deposits or faulting. The Big Salmon fault is interpreted to dip southwest, implying that rocks of the Yukon–Tanana terrane extend beneath Quesnellia. Stikinia and Quesnellia underlie up to 5–8 km of Triassic to Early Cretaceous sedimentary strata, and appear to be a single allochthon within an 18–20 km deep synform above the Yukon–Tanana terrane, which we name the Northern Intermontane synform. In general, reflection geometries in the upper crust are complex, but are consistent with large-scale imbricate structures that have been dissected into numerous blocks by displacement along moderately to steeply dipping strike-slip faults, which may be part of a crustal-scale flower structure extending to the base of the crust.
Climatic conditions for emergence and flight of mountain pine beetle: implications for long-distance dispersal
Authors: Chen Huapeng , Jackson Peter L.
Published: April 2017

A significant shift in the mountain pine beetle (Dendroctonus ponderosae Hopkins, 1902) range has been attributed to long-distance dispersal from the observed spatiotemporal patterns of beetle infestations in the recent outbreak in western Canada. However, long-distance dispersal is still the least understood aspect of mountain pine beetle ecology. In particular, the mechanisms responsible for the three major phases of long-distance dispersal, the ascent, transport, and descent, are poorly known. In this study, we used the North American Regional Reanalysis meteorological data (1999–2010) to determine climate conditions under and above the forest canopy during mountain pine beetle emergence and flight at the landscape scale. We found that climate conditions are distinct during emergence and flight. They provide an ideal underlying environment to facilitate the potential long-distance dispersal. Climate conditions are unstable under the forest canopy during emergence, which would help loft beetles above the forest canopy to initiate long-distance dispersal. The first direct evidence from wind directions above the forest canopy suggests that atmospheric transportation of mountain pine beetle in the planetary boundary layer is aided by wind.
Experimental branch cooling increases foliar sugar and anthocyanin concentrations in sugar maple at the end of the growing season
Authors: Schaberg Paul G. , Murakami Paula F. , Butnor John R. , Hawley Gary J.
Published: April 2017

Autumnal leaf anthocyanin expression is enhanced following exposure to a variety of environmental stresses and may represent an adaptive benefit of protecting leaves from those stresses, thereby allowing for prolonged sugar and nutrient resorption. Past work has shown that experimentally induced sugar accumulations following branch girdling triggers anthocyanin biosynthesis. We hypothesized that reduced phloem transport at low autumnal temperatures may increase leaf sugar concentrations that stimulate anthocyanin production, resulting in enhanced tree- and landscape-scale color change. We used refrigerant-filled tubing to cool individual branches in a mature sugar maple (Acer saccharum Marsh.) tree to test whether phloem cooling would trigger foliar sugar accumulations and enhance anthocyanin biosynthesis. Cooling increased foliar sucrose, glucose, and fructose concentrations 2- to nearly 10-fold (depending on the specific sugar and sampling date) relative to controls and increased anthocyanin concentrations by approximately the same amount. Correlation analyses indicated a strong and steady positive relationship between anthocyanin and sugar concentrations, which was consistent with a mechanistic link between cooling-induced changes in these constituents. Tested here at the branch level, we propose that low temperature induced reductions in phloem transport may be responsible for increases in foliar sugars that trigger anthocyanin displays at grander scales.
Hilbert regularity of Stanley–Reisner rings
Authors: Bruns Winfried , Saremi Hero
Published: April 2017

In this note, we characterize the Hilbert regularity of the Stanley–Reisner ring [Formula: see text] in terms of the [Formula: see text]-vector and the [Formula: see text]-vector of a simplicial complex [Formula: see text]. We also compute the Hilbert regularity of a Gorenstein algebra.
More knots in knots: A study of classical knot diagrams
Authors: Millett Kenneth C. , Rich Alex
Published: April 2017

The structure of classical minimal prime knot presentations suggests that there are often, perhaps always, subsegments that present either the trefoil or the figure-eight knot. A comprehensive study of the subknots of the minimal prime knot presentations through 15 crossings shows that this is always the case for these knot presentations. Among this set of 313, 258 prime knot presentation, there are only 547, or 0.17%, that do not contain a trefoil subknot. Thus, 99.83% of minimal prime knot presentations through 15 crossings contain trefoil subknots. We identify several infinite minimal alternating prime knot families that do not contain trefoil subknots but always contain figure-eight knots. We discuss the statistics of subknots of prime knots and, using knot presentation fingerprints, illustrate the complex character of the subknots of these classic minimal prime knot presentations. We conclude with a discussion the conjectures and open questions that have grown out of our research.
The palette numbers of 2-bridge knots
Authors: Nakamura Takuji , Nakanishi Yasutaka , Saito Masahico , Satoh Shin
Published: April 2017

We prove that for any odd [Formula: see text], the [Formula: see text]-palette number of any effectively [Formula: see text]-colorable [Formula: see text]-bridge knot is equal to [Formula: see text]. Namely, there is an effectively [Formula: see text]-colored diagram of the [Formula: see text]-bridge knot such that the number of distinct colors that appeared in the diagram is exactly equal to [Formula: see text].
Surface solitons supported by 𝒫𝒯-symmetric lattice with spatially modulated nonlinearity
Authors: Li Xin , Yu Rangang , Zhang Neng
Published: April 2017

We report on the formation and stability of induced surface solitons in parity–time ([Formula: see text]) symmetric periodic systems with spatially modulated nonlinearity. We discover that the spatially modulation of the nonlinearity can affect the existence and stability of surface solitons. These surface solitons can be formed in the semi-infinite and first bandgap. Stability analysis shows that odd surface solitons belonging to semi-infinite bandgap are linearly stably in low power domain, and the stable domain becomes narrow with increasing the strength of spatially modulated nonlinearity, both even surface solitons in semi-infinite bandgap and surface solitons in first bandgap are unstable in their existence domain.
Nematicons in liquid crystals by extended trial equation method
Authors: Ekici Mehmet , Mirzazadeh Mohammad , Sonmezoglu Abdullah , Ullah Malik Zaka , Zhou Qin , Moshokoa Seithuti P. , Biswas Anjan , Belic Milivoj
Published: April 2017

This paper employs extended trial equation method to retrieve nematicons in liquid crystals from its governing equation. In addition, several other forms of solution naturally emerged from the integration algorithm. These are shock waves, singular solitons, snoidal waves, periodic singular waves, plane waves and others. These variety of solutions are being reported for the first time in the context of liquid crystals.
Spontaneous spatial fractal pattern formation in dispersive systems
Authors: Huang J. G. , Christian J. M. , McDonald G. S.
Published: April 2017

We report spontaneous spatial optical fractal patterns in a ring cavity containing a thin slice of diffusive Kerr-type material. The Turing threshold instability condition is derived through linear analysis, and static patterns are found to be described by spectra with multiple-minimum characteristics. These theoretical predictions are subsequently verified through numerical simulations with both one and two transverse dimensions. Our findings support that a proposed fractal-generating criterion for nonlinear wave-based systems with thin-slice host media can have independence with respect to both system geometry and nonlinearity.
Modeling and simulation of a singly resonant fiber optical parametric oscillator
Authors: Pakarzadeh Hassan , Dehghanian Zahra , Taghizadeh Mostafa
Published: April 2017

So far, the commonly used optical parametric oscillators (OPOs) relying on [Formula: see text] nonlinearity in the bulk materials have been extensively investigated both theoretically and experimentally, but not enough attention has been paid to OPOs based on [Formula: see text] nonlinearity in optical fibers. In this paper, a singly resonant fiber optical parametric oscillator (FOPO) is theoretically studied and its main aspects are simulated. Also, impacts of various parameters including the pump and signal wavelengths, the fiber length and dispersion as well as the input coupler on the conversion efficiency of the FOPO are investigated. Finally, the simulation results are compared with the available experimental data and a very good agreement is obtained.
A strongly indefinite Choquard equation with critical exponent due to the Hardy–Littlewood–Sobolev inequality
Authors: Gao Fashun , Yang Minbo
Published: April 2017

In this paper, we are concerned with the following nonlinear Choquard equation [Formula: see text] where [Formula: see text], [Formula: see text] and [Formula: see text]. If [Formula: see text] lies in a gap of the spectrum of [Formula: see text] and [Formula: see text] is of critical growth due to the Hardy–Littlewood–Sobolev inequality, we obtain the existence of nontrivial solutions by variational methods. The main result here extends and complements the earlier theorems obtained in [N. Ackermann, On a periodic Schrödinger equation with nonlocal superlinear part, Math. Z. 248 (2004) 423–443; B. Buffoni, L. Jeanjean and C. A. Stuart, Existence of a nontrivial solution to a strongly indefinite semilinear equation, Proc. Amer. Math. Soc. 119 (1993) 179–186; V. Moroz and J. Van Schaftingen, Existence of groundstates for a class of nonlinear Choquard equations, Trans. Amer. Math. Soc. 367 (2015) 6557–6579].
Calculating Galois groups of third-order linear differential equations with parameters
Authors: Minchenko Andrei , Ovchinnikov Alexey
Published: April 2017

Motivated by developing algorithms that decide hypertranscendence of solutions of extensions of the Bessel differential equation, algorithms computing the unipotent radical of a parameterized differential Galois group have been recently developed. Extensions of Bessel’s equation, such as the Lommel equation, can be viewed as homogeneous parameterized linear differential equations of the third order. In this paper, we give the first known algorithm that calculates the differential Galois group of a third-order parameterized linear differential equation.
Isolated singularities of positive solutions for Choquard equations in sublinear case
Authors: Chen Huyuan , Zhou Feng
Published: April 2017

Our purpose of this paper is to study the isolated singularities of positive solutions to Choquard equation in the sublinear case [Formula: see text] [Formula: see text] where [Formula: see text] and [Formula: see text] is the Riesz potential, which appears as a nonlocal term in the equation. We investigate the nonexistence and existence of isolated singular solutions of Choquard equation under different range of the pair of exponent [Formula: see text]. Furthermore, we obtain qualitative properties for the minimal singular solutions of the equation.
Large and moderate deviations for bounded functions of slowly mixing Markov chains
Authors: Dedecker Jérôme , Gouëzel Sébastien , Merlevède Florence
Published: April 2017

We consider Markov chains which are polynomially mixing, in a weak sense expressed in terms of the space of functions on which the mixing speed is controlled. In this context, we prove polynomial large and moderate deviations inequalities. These inequalities can be applied in various natural situations coming from probability theory or dynamical systems. Finally, we discuss examples from these various settings showing that our inequalities are sharp.
Additive decomposition of ideals
Authors: Karparvar Ali Mohammad , Amini Babak , Amini Afshin , Sharif Habib
Published: April 2017

In this paper, we investigate decomposition of (one-sided) ideals of a unital ring [Formula: see text] as a sum of two (one-sided) ideals, each being idempotent, nil, nilpotent, T-nilpotent, or a direct summand of [Formula: see text]. Among other characterizations, we prove that in a polynomial identity ring every (one-sided) ideal is a sum of a nil (one-sided) ideal and an idempotent (one-sided) ideal if and only if the Jacobson radical [Formula: see text] of [Formula: see text] is nil and [Formula: see text] is von Neumann regular. As a special case, these conditions for a commutative ring [Formula: see text] are equivalent to [Formula: see text] having zero Krull dimension. While assuming Köthe’s conjecture in several occasions to be true, we also raise a question, the affirmative answer to which leads to the truth of the conjecture.
A cellular basis of the q-Brauer algebra related with Murphy bases of Hecke algebras
Authors: Nguyen Dung Tien
Published: April 2017

A new basis of the [Formula: see text]-Brauer algebra is introduced, which is a lift of Murphy bases of Hecke algebras of symmetric groups. This basis is shown to be a cellular basis in the sense of Graham and Lehrer. Using combinatorial tools we prove that the non-isomorphic simple [Formula: see text]-Brauer modules are indexed by the [Formula: see text]-restricted partitions of [Formula: see text] where [Formula: see text] is an integer, [Formula: see text]. When the [Formula: see text]-Brauer algebra has low dimension a criterion of semisimplicity is given, which is used to show that the [Formula: see text]-Brauer algebra is in general not isomorphic to the BMW-algebra.
Boundedness of composition operators between weighted Bergman spaces
Authors: Wolf Elke
Published: April 2017

This paper contained mathematical errors and its publication has been retracted from AEJM.
Improved graded finite elements with applications in simulating non-homogeneous elastic, piezoelectric and magneto-electro-elastic materials
Authors: Xiong Tao , Guo Yun-Kun , Li Yong-Dong , Zhang Hong-Cai
Published: April 2017

Graded finite elements (GFEs) provide a promising way for simulating functionally graded materials. Nevertheless, the existing GFE method takes the conventional isoparametric transform functions as a unified representation for the material non-homogeneity in each element regardless of the practical global distribution forms of material properties. This inevitably leads to a certain difference between the local formulation of material property variation in the elements and the corresponding global gradation patterns. In order to eliminate this difference, an improved GFE algorithm is proposed in the present article. The property distribution in the element is formulated by substituting the isoparametric transform of the coordinates directly into the corresponding global gradation functions. Therefore, the local property distribution is always consistent with the global one. Both the improved six-node triangular elements (T6) and eight-node quadrilateral elements (Q8) are developed for non-homogeneous elastic, piezoelectric and magneto-electro-elastic materials, respectively. Exact solutions in three special cases are presented to make comparison with the numerical results, and the accuracy of the proposed algorithm is verified. It is demonstrated that the improved GFE is an effective method for the numerical simulation of functionally graded materials.