bluuebunny/crossref_metadata_2025 huggingface dataset:
The Seroprevalence of Human Cystic Echinococcosis in Iran: A Systematic Review and Meta-Analysis Study
Authors: Shafiei Reza , Teshnizi Saeed Hosseini , Kalantar Kurosh , Gholami Maryam , Mirzaee Golnush , Mirzaee Fatemeh
Published: October 2016

Human cystic echinococcosis (HCE), a zoonotic infection of the larval stage ofEchinococcus granulosus, has high effect on public health in human population all around the world. Iran is one of the most important endemic areas in the Middle East. This systematic review and meta-analysis was performed to evaluate the seroprevalence of HCE in Iranian population. An electronic search for articles from 1985 until April 2015 was performed using data bases PubMed, Scopus, Google Scholar, Magiran, IranMedex, Iran Doc, and Scientific Information Database (SID) both in English and in Persian. A random-effects meta-analysis was used to combine results from individual studies. The information was analyzed by STATA version 11.1. A total of 33 articles met our eligibility criteria and were included in a meta-analysis. The pooled estimate of the prevalence of HCE based on random-effects model was estimated 6.0% (95% CI: 4.0%, 7.0%). The prevalence of the disease significantly increased with age and prevalence rate in males was significantly lower than females (p<0.001). The using of CIE or CCIEP method was also significantly greater than the other methods (p<0.001). There was a publication bias in prevalence of studies. HCE is highly prevalent in Iran. Public education for preventive strategies and finally reducing transmission of the parasite and infection in population is needed.
Strengthened Corticosubcortical Functional Connectivity during Muscle Fatigue
Authors: Jiang Zhiguo , Wang Xiao-Feng , Yue Guang H.
Published: October 2016

The present study examined functional connectivity (FC) between functional MRI (fMRI) signals of the primary motor cortex (M1) and each of the three subcortical neural structures, cerebellum (CB), basal ganglia (BG), and thalamus (TL), during muscle fatigue using the quantile regression technique. Understanding activation relation between the subcortical structures and the M1 during prolonged motor performance should help delineate how central motor control network modulates acute perturbations at peripheral sensorimotor system such as muscle fatigue. Ten healthy subjects participated in the study and completed a 20-minute intermittent handgrip motor task at 50% of their maximal voluntary contraction (MVC) level. Quantile regression analyses were carried out to compare the FC between the contralateral (left) M1 and CB, BG, and TL in the minimal (beginning 100 s) versus significant (ending 100 s) fatigue stages. Widespread, statistically significant increases in FC were found in bilateral BG, CB, and TL with the left M1 during significant versus minimal fatigue stages. Our results imply that these subcortical nuclei are critical components in the motor control network and actively involved in modulating voluntary muscle fatigue, possibly, by working together with the M1 to strengthen the descending central command to prolong the motor performance.
Underdetermined Separation of Speech Mixture Based on Sparse Bayesian Learning
Authors: Wang Zhe , Wang Luyun , Li Xiumei , Zhao Lifan , Bi Guoan
Published: October 2016

This paper describes a novel algorithm for underdetermined speech separation problem based on compressed sensing which is an emerging technique for efficient data reconstruction. The proposed algorithm consists of two steps. The unknown mixing matrix is firstly estimated from the speech mixtures in the transform domain by using K-means clustering algorithm. In the second step, the speech sources are recovered based on an autocalibration sparse Bayesian learning algorithm for speech signal. Numerical experiments including the comparison with other sparse representation approaches are provided to show the achieved performance improvement.
A Bridge Deflection Monitoring System Based on CCD
Authors: Shan Baohua , Wang Lei , Huo Xiaoyang , Yuan Wenting , Xue Zhilin
Published: October 2016

For long-term monitoring of the midspan deflection of Songjiazhuang cloverleaf junction on 309 national roads in Zibo city, this paper proposes Zhang’s calibration-based DIC deflection monitoring method. CCD cameras are used to track the change of targets’ position, Zhang’s calibration algorithm is introduced to acquire the intrinsic and extrinsic parameters of CCD cameras, and the DIC method is combined with Zhang’s calibration algorithm to measure bridge deflection. The comparative test between Zhang’s calibration and scale calibration is conducted in lab, and experimental results indicate that the proposed method has higher precision. According to the deflection monitoring scheme, the deflection monitoring software for Songjiazhuang cloverleaf junction is developed by MATLAB, and a 4-channel CCD deflection monitoring system for Songjiazhuang cloverleaf junction is integrated in this paper. This deflection monitoring system includes functions such as image preview, simultaneous collection, camera calibration, deflection display, and data storage. In situ deflection curves show a consistent trend; this suggests that the proposed method is reliable and is suitable for the long-term monitoring of bridge deflection.
The Modeling and Control of a Singular Biological Economic System with Time Delay in a Polluted Environment
Authors: Zhang Yi , Zhao Huiying , Zhang Qingling
Published: October 2016

This paper brings up the idea of a biological economic system with time delay in a polluted environment. Firstly, by proper linear transformation and parametric method, the singular time-delay systems are transformed to differential time-delay systems. Then, using center manifold theory and Poincare normal form method, the direction of Hopf bifurcation and the stability and period of its periodic orbits are analysed. At last, we have performed numerical simulation to support the analytical results.
Prevalence of Needlestick Injury and Its Potential Risk among Veterinarians in Nigeria
Authors: Mshelbwala Philip Paul , Weese J. Scott , Idris Jibrin Manu
Published: October 2016

A cross sectional study using multistage sampling method by means of structured interviewer administered questionnaire was designed to estimate the rate of occurrence of needlestick injuries among veterinarians involved in clinical practice and to evaluate needle handling practices and risk factors. The study was carried out during the months of August–November 2015. Out of the 215 veterinarians that participated in the survey, 171 (79.5%) reported to have suffered needlestick injuries (NSIs). In the multivariable model, only male sex (OR 2.8, 95% CI 1.4–6.0, and P=0.006) and working with poultry daily (OR 2.4, 95% CI 1.1–6.2, and P=0.036) were significantly associated with NSI. Most (111, 64.9%) veterinarians had discomfort including pain, headache, fever, worry, and local numbness from NSIs; however, none was hospitalised. Only 1 (0.6%) had lost time at work. The approach to needlestick injury avoidance was poor and most (98.8%) NSIs were not reported. The findings of this research call for comprehensive health and injection safety programs for veterinarians involved in clinical practice.
Characterization of Energy Availability in RF Energy Harvesting Networks
Authors: Oliveira Daniela , Oliveira Rodolfo
Published: October 2016

The multiple nodes forming a Radio Frequency (RF) Energy Harvesting Network (RF-EHN) have the capability of converting received electromagnetic RF signals in energy that can be used to power a network device (the energy harvester). Traditionally the RF signals are provided by high power transmitters (e.g., base stations) operating in the neighborhood of the harvesters. Admitting that the transmitters are spatially distributed according to a spatial Poisson process, we start by characterizing the distribution of the RF power received by an energy harvester node. Considering Gamma shadowing and Rayleigh fading, we show that the received RF power can be approximated by the sum of multiple Gamma distributions with different scale and shape parameters. Using the distribution of the received RF power, we derive the probability of a node having enough energy to transmit a packet after a given amount of charging time. The RF power distribution and the probability of a harvester having enough energy to transmit a packet are validated through simulation. The numerical results obtained with the proposed analysis are close to the ones obtained through simulation, which confirms the accuracy of the proposed analysis.
Potential Therapeutic Strategies for Hypertension‐Exacerbated Cardiotoxicity of Anticancer Drugs
Authors: Kuriakose Robin K. , Kukreja Rakesh C. , Xi Lei
Published: October 2016

Despite their recognized cardiotoxic effects, anthracyclines remain an essential component in many anticancer regimens due to their superior antitumor efficacy. Epidemiologic data revealed that about one‐third of cancer patients have hypertension, which is the most common comorbidity in cancer registries. The purpose of this review is to assess whether anthracycline chemotherapy exacerbates cardiotoxicity in patients with hypertension. A link between hypertension comorbidity and anthracycline‐induced cardiotoxicity (AIC) was first suggested in 1979. Subsequent preclinical and clinical studies have supported the notion that hypertension is a major risk factor for AIC, along with the cumulative anthracycline dosage. There are several common or overlapping pathological mechanisms in AIC and hypertension, such as oxidative stress. Current evidence supports the utility of cardioprotective modalities as adjunct treatment prior to and during anthracycline chemotherapy. Several promising cardioprotective approaches against AIC pathologies include dexrazoxane, early hypertension management, and dietary supplementation of nitrate with beetroot juice or other medicinal botanical derivatives (e.g., visnagin and Danshen), which have both antihypertensive and anti‐AIC properties. Future research is warranted to further elucidate the mechanisms of hypertension and AIC comorbidity and to conduct well‐controlled clinical trials for identifying effective clinical strategies to improve long‐term prognoses in this subgroup of cancer patients.
Flutter and Thermal Buckling Analysis for Composite Laminated Panel Embedded with Shape Memory Alloy Wires in Supersonic Flow
Authors: Shao Chonghui , Cao Dengqing , Xu Yuqian , Zhao Hai
Published: October 2016

The flutter and thermal buckling behavior of laminated composite panels embedded with shape memory alloy (SMA) wires are studied in this research. The classical plate theory and nonlinear von-Karman strain-displacement relation are employed to investigate the aeroelastic behavior of the smart laminated panel. The thermodynamic behaviors of SMA wires are simulated based on one-dimensional Brinson SMA model. The aerodynamic pressure on the panel is described by the nonlinear piston theory. Nonlinear governing partial differential equations of motion are derived for the panel via the Hamilton principle. The effects of ply angle of the composite panel, SMA layer location and orientation, SMA wires temperature, volume fraction and prestrain on the buckling, flutter boundary, and amplitude of limit cycle oscillation of the panel are analyzed in detail.
Low-Energy Traumatic Obturator Hip Dislocation with Ipsilateral Femoral Shaft Fracture in a Patient with Omolateral Knee Arthroplasty
Authors: Gazzotti G. , Patrizio L. , Dall’Aglio S. , Sabetta E.
Published: October 2016

Ipsilateral obturator hip dislocation and femoral shaft fracture are rare. We report such a case in an older woman after a low-energy injury. She had a knee prostheses in the same limb. The patient was treated by open manipulative reduction of the luxation without opening joint and open reduction and internal fixation of the femur with angular stability plate and screws. We could not find a similar case in the literature. An early diagnosis of the dislocation is crucial in order to obtain good results. Great awareness and radiologic examination are fundamental to achieve precocious diagnosis of both these rare combined injuries, as treatment in these cases is considered an emergency. The first step was an attempt to reduce the dislocation by closed means but it failed. Then we performed a short approach at the trochanteric region and used Lambotte forceps to manoeuvre the proximal femur without opening the joint achieving reduction. Thereafter the femoral shaft fracture underwent open reduction and internal fixation with an angular stable plate. After a 2-year follow-up the outcome was very good.
Improved DDA Method Based on Explicitly Solving Contact Constraints
Authors: Zhao Jian , Xiao Ming , Chen Juntao , Li Dongdong
Published: October 2016

This paper proposes an improved DDA method based on explicitly solving contact constraints. The potential energy function generated by contacting, which contains only displacement variables as an unknown, is deduced based on the approximated step function and Lagrange interpolation, and the displacement variables and contact constraints are obtained via the variable metric method by analyzing the potential energy extremum. There is no need to conduct the open-close iteration during the process of calculation. The improved DDA method based on explicitly solving contact constraints has high precision and a more stable and more robust computational convergence. The accuracy and iterative stability of the improved DDA method are verified using two numerical examples.
Two-Phase Flow in Wire Coating with Heat Transfer Analysis of an Elastic-Viscous Fluid
Authors: Khan Zeeshan , Shah Rehan Ali , Islam Saeed , Jan Bilal
Published: October 2016

This work considers two-phase flow of an elastic-viscous fluid for double-layer coating of wire. The wet-on-wet (WOW) coating process is used in this study. The analytical solution of the theoretical model is obtained by Optimal Homotopy Asymptotic Method (OHAM). The expression for the velocity field and temperature distribution for both layers is obtained. The convergence of the obtained series solution is established. The analytical results are verified by Adomian Decomposition Method (ADM). The obtained velocity field is compared with the existing exact solution of the same flow problem of second-grade fluid and with analytical solution of a third-grade fluid. Also, emerging parameters on the solutions are discussed and appropriate conclusions are drawn.
Interaction between Thalamus and Hippocampus in Termination of Amygdala-Kindled Seizures in Mice
Authors: Zhang Zhen , Li Jia-Jia , Lu Qin-Chi , Gong Hai-Qing , Liang Pei-Ji , Zhang Pu-Ming
Published: October 2016

The thalamus and hippocampus have been found both involved in the initiation, propagation, and termination of temporal lobe epilepsy. However, the interaction of these regions during seizures is not clear. The present study is to explore whether some regular patterns exist in their interaction during the termination of seizures. Multichannel in vivo recording techniques were used to record the neural activities from the cornu ammonis 1 (CA1) of hippocampus and mediodorsal thalamus (MDT) in mice. The mice were kindled by electrically stimulating basolateral amygdala neurons, and Racine’s rank standard was employed to classify the stage of behavioral responses (stage 1~5). The coupling index and directionality index were used to investigate the synchronization and information flow direction between CA1 and MDT. Two main results were found in this study.(1)High levels of synchronization between the thalamus and hippocampus were observed before the termination of seizures at stage 4~5 but after the termination of seizures at stage 1~2.(2)In the end of seizures at stage 4~5, the information tended to flow from MDT to CA1. Those results indicate that the synchronization and information flow direction between the thalamus and the hippocampus may participate in the termination of seizures.
Efficacy and Safety of Sofosbuvir Plus Ribavirin Treatment for Patients with Chronic Hepatitis C Genotype 2
Authors: Sugimoto Kayo , Kim Soo Ki , Kim Soo Ryang , Kobayashi Mana , Kato Airi , Morimoto Eri , Imoto Susumu , Kim Chi Wan , Tanaka Yasuhito , Kudo Masatoshi , Yano Yoshihiko , Hayashi Yoshitake
Published: October 2016

Objectives: The efficacy of sofosbuvir plus ribavirin (RBV) treatment for hepatitis C virus (HCV) genotype 2 focusing on virological response was compared with that of pegylated interferon (peg-IFN) plus RBV treatment. Safety of the former focusing on the decline in hemoglobin levels was compared with that of the latter and assessed in terms of age and inosine triphosphatase (ITPA). Methods: Patients (n = 17) receiving sofosbuvir plus RBV and those (n = 24) receiving peg-IFN plus RBV diagnosed with chronic HCV genotype 2 were enrolled in this study, and the efficacy and safety of both treatments were assessed. Results: Rapid virological response was attained with sofosbuvir plus RBV treatment compared with peg-IFN plus RBV treatment. All patients under sofosbuvir plus RBV treatment achieved end-of-treatment response compared with 70% who sustained viral response under the peg-IFN plus RBV treatment, with the former demonstrating greater virological response. The decline in hemoglobin levels under the former treatment was greater than that under the latter and in patients over 65 years of age with ITPA gene major. Conclusion: Efficacy and safety of sofosbuvir plus RBV treatment were clearly demonstrated compared with those of peg-IFN plus RBV treatment. The decline in hemoglobin levels was not related to the discontinuation of the former treatment, irrespective of age or the effect of the ITPA gene.
US-US Fusion Imaging in Radiofrequency Ablation for Liver Metastases
Authors: Minami Yasunori , Minami Tomohiro , Chishina Hirokazu , Kono Masashi , Arizumi Tadaaki , Takita Masahiro , Yada Norihisa , Hagiwara Satoru , Ida Hiroshi , Ueshima Kazuomi , Nishida Naoshi , Kudo Masatoshi
Published: October 2016

Objective: Radiofrequency ablation (RFA) induces gas bubbles in ablation zones, and the ablative margin cannot be evaluated accurately on ultrasound (US) during and immediately after RFA. This study assessed the usefulness of US-US fusion imaging to visualize the ablative margin of RFA for liver metastasis. Methods: RFA guided by US-US fusion imaging was performed on 12 targeted tumors in 10 patients. Secondary hepatic malignancies included patients with colorectal cancer (n = 4), breast cancer (n = 2), lung cancer (n = 1), gastrointestinal stromal tumor (n = 1), pancreatic neuroendocrine tumor (n = 1), and adrenocortical carcinoma (n = 1). The maximal diameter of the tumors ranged from 0.8 to 4.0 cm (mean ± SD 1.6 ± 0.9 cm). Results: The mean number of electrode insertions was 1.6 per session (range 1-3). Technically, effective ablation was achieved in a single session in all patients, and safety ablative margins were confirmed on contrast-enhanced CT for early assessment of tumor response. There were no serious adverse events or procedure-related complications. During the follow-up period (median 220 days, range 31-417 days), none of the patients showed local tumor progression. Conclusion: US-US fusion imaging could show the tumor images before ablation and the ablative area on US in real time. The image overlay of US-US fusion imaging made it possible to evaluate the ablative margin three dimensionally according to the US probe action. Therefore, US-US fusion imaging can contribute to RFA therapy with a safety margin, that is, the so-called precise RFA.
Recent Trends in the Management of Hepatocellular Carcinoma with Special Emphasis on Treatment with Regorafenib and Immune Checkpoint Inhibitors
Authors: Kudo Masatoshi
Published: October 2016

Hepatocellular carcinoma (HCC) is the fifth most common cancer and the third leading cause of cancer deaths worldwide. Sonazoid-enhanced ultrasound and gadolinium ethoxybenzyl diethylenetriamine pentaacetic acid-enhanced MRI are the most important imaging modalities in diagnosing HCC. There are 2 non-contradictory HCC treatment algorithms in Japan. Hepatic arterial infusion chemotherapy plays an important role in the treatment of advanced HCC with main or branch portal vein invasion. Regorafenib, as a second-line systemic treatment, prolongs survival in patients with intermediate and advanced HCC who progressed on sorafenib. In recent clinical trials, immune check point inhibitors show promising results for the treatment of HCC. This review describes recent trends in the management of HCC.
Prospective Risk Analysis of Hepatocellular Carcinoma in Patients with Chronic Hepatitis C by Ultrasound Strain Elastography
Authors: Yada Norihisa , Sakurai Toshiharu , Minami Tomohiro , Arizumi Tadaaki , Takita Masahiro , Hagiwara Satoru , Ida Hiroshi , Ueshima Kazuomi , Nishida Naoshi , Kudo Masatoshi
Published: October 2016

Objective: We have reported about real-time tissue elastography (RTE), which displays relative strain by measuring the relative distortion of the tissue, and found this information to be useful for diagnosing liver fibrosis. However, its use in predicting hepatocellular carcinoma has not been reported as yet. Here, we investigated RTE to predict liver carcinogenesis in patients with chronic hepatitis C virus (HCV) infection. Methods: We enrolled 160 patients with chronic HCV, who were followed up for 39.9 ± 22.9 weeks (median). They underwent RTE and then ultrasounds every 3-6 months. Results: Respective cumulative liver cancer incidences for years 1, 2, 3, 4, and 5 were, for the entire cohort: 2.0, 5.6, 8.8, 13.1, and 23.9%; for those whose liver fibrosis index (LFI) was ≤2.0: 0.0, 0.0, 0.0, 0.0, and 0.0%; for those whose LFI was 2-2.8: 0.0, 7.4, 7.4, 13.2 and 19.9%; and for those whose LFI was >2.8: 12.9, 12.9, 21.7, 31.4, and 31.4% (p = 0.011; log-rank test). Conclusions: Measurements of LFI by strain imaging can effectively predict liver cancer risk in patients with chronic HCV infection.
Zinc Intake, Zinc Bioavailability and Plasma Zinc in Obese Adolescents with Clinical Insulin Resistance Following Low Energy Diets
Authors: Ho Mandy , Heath Anne-Louise M. , Gow Megan , Baur Louise A. , Cowell Chris T. , Samman Samir , Garnett Sarah P.
Published: October 2016

Background: Zinc has a critical role in metabolism and growth. This study aims to determine the effects of low-energy diets differing in macronutrient composition on zinc intake, estimated zinc bioavailability (phytate:zinc molar ratio) and plasma zinc concentration and associations between zinc status and cardiometabolic markers in obese adolescents with clinical insulin resistance (IR). Methods: Eighty-seven obese adolescents (10-17 years, body mass index z-score 2.3 ± 0.37) with clinical IR were randomized to a low-energy diet (6.0-8.0 MJ), which was either high carbohydrate or moderate carbohydrate with increased protein. Twenty-four-hour dietary recalls were collected at 6, 9 and 12 weeks. Plasma zinc concentration and cardiometabolic markers were assessed at baseline and 12 weeks. Results: Zinc intake did not differ between the 2 diet groups (p = 0.612). The high-carbohydrate group had a higher phytate intake (894 vs. 671 mg, p = 0.018) and phytate:zinc molar ratio (9.4 vs. 7.4, p = 0.009) than the increased-protein group. Plasma zinc concentration did not change from baseline in either of the diet groups, but correlated positively with zinc intake (r = 0.235, p = 0.042) and % energy from protein (r = 0.383, p = 0.001), and inversely with % energy from carbohydrate (r = -0.296, p = 0.010). Conclusions: Low energy diets for obese adolescents at risk of diabetes may need increased protein content to optimize zinc bioavailability.
Requests as Orders
Authors: Rivero García Luis
Published: October 2016

The authenticity of Ov.Met.13.377-379 is defended, based on arguments of form and literary composition.
Constantinople and the Echo Chamber: The Vlachs in the French Crusade Chronicles
Authors: Curta Florin
Published: October 2016

The chroniclers of the Fourth Crusade (Geoffroi de Villehardouin, Henri de Valenciennes, and Robert de Clari) have much to say about the Vlachs. Much of that information results from direct contact with the Vlachs, particularly in the case of Villehardouin and Henri de Valenciennes. However, several issues characterizing the Vlachs, especially in Robert de Clari’s chronicle, are remarkably similar to stories that may be found in Niketas Choniates. The paper analyzes the role attributed to the Vlachs in the French chronicles, and attempts to explain the similarity to the coverage of things Vlach in Niketas Choniates. As such, the paper offers an examination of all Byzantine sources mentioning the Vlachs before Choniates and of non-Byzantine sources such as Benjamin of Tudela. The conclusion is that the image of the Vlachs in the French chronicles derives from stories about them circulating in twelfth-century Constantinople.
Lerneca inalata beripocone subsp. nov. (Orthoptera: Phalangopsidae; Luzarinae): a new taxon for the northern Pantanal of Brazil
Authors: LIMA RAYSA MARTINS , MARTINS LUCIANO DE PINHO , PEREIRA MARCELO RIBEIRO , GANCHEV TODOR D. , JAHN OLAF , LHANO MARCOS GONÇALVES , MARQUES MARINÊZ ISAAC , SCHUCHMANN KARL-L
Published: October 2016

The first record of the Orthoptera species Lerneca inalata for Brazil is presented here. The taxon is represented by a new subspecies Lerneca inalata beripocone subsp. nov. (Phalangopsidae, Luzarinae), collected in the Pantanal of Poconé, Mato Grosso, Brazil. This work includes morphological and morphometric data as well as descriptions of female genitalia and calling song. The new subspecies has as diagnostic features the male genitalia with six ventral spines on the B sclerite, the first spine having a subtle bifurcation; the mid-region of the strongly sclerotized pseudepiphallus; inclination of C sclerite with slightly concave curvature; tegmina-length ratio and the speculum (syn. mirror) width approximately three times the length of the apical area. The description of the female genitalia and the calling song is presented for the first time for the species Lerneca inalata. A distribution map covers the local occurrence of its subspecies.
Rediscovery and redescription of a deep-sea shrimp Lebbeus longidactylus (Kobjakova, 1936) (Crustacea: Decapoda: Caridea: Thoridae) based on material from the Nemuro Strait, southwestern Sea of Okhotsk
Authors: KOMAI TOMOYUKI , MATSUZAKI KOJI , HIBINO MAI
Published: October 2016

A poorly known thorid shrimp, Lebbeus longidactylus (Kobjakova, 1936), is redescribed on the basis of material collected from the Nemuro Strait, southwestern part of the Sea of Okhotsk, at depths of 600–800 m. The newly collected samples represent the second finding of this rarely collected species since the type description. The species belongs to the informal species group characterized by the possession of epipods on maxilliped 3 to pereopod 2, and appears close to L. scrippsi Wicksten & Méndez, 1982, known from the eastern Pacific, in that the slender dactyli of pereopods 3–5 each terminate in a simple, non-biunguiculate tip and by having accessory spiniform setae restricted to the proximal half of the flexor margin. The elongate rostrum with more numerous dorsal spines, more numerous dorsolateral spiniform setae on the telson, and a single spine on the dorsodistal margin of article 1 of the antennular peduncle readily differentiate L. longidactylus from L. scrippsi.
A Containerized Mesoscale Model and Analysis Toolkit to Accelerate Classroom Learning, Collaborative Research, and Uncertainty Quantification
Authors: Hacker Joshua P. , Exby John , Gill David , Jimenez Ivo , Maltzahn Carlos , See Timothy , Mullendore Gretchen , Fossell Kathryn
Published: October 2016

Numerical weather prediction (NWP) experiments can be complex and time consuming; results depend on computational environments and numerous input parameters. Delays in learning and obtaining research results are inevitable. Students face disproportionate effort in the classroom or beginning graduate-level NWP research. Published NWP research is generally not reproducible, introducing uncertainty and slowing efforts that build on past results. This work exploits the rapid emergence of software container technology to produce a transformative research and education environment. The Weather Research and Forecasting (WRF) Model anchors a set of linked Linux-based containers, which include software to initialize and run the model, to analyze results, and to serve output to collaborators. The containers are demonstrated with a WRF simulation of Hurricane Sandy. The demonstration illustrates the following: 1) how the often-difficult exercise in compiling the WRF and its many dependencies is eliminated, 2) how sharing containers provides identical environments for conducting research, 3) that numerically reproducible results are easily obtainable, and 4) how uncertainty in the results can be isolated from uncertainty arising from computing system differences. Numerical experiments designed to simultaneously measure numerical reproducibility and sensitivity to compiler optimization provide guidance for interpreting NWP research. Reproducibility is independent from the operating system and hardware. Results here show numerically identical output on all computing platforms tested. Performance reproducibility is also demonstrated. The result is an infrastructure capable of accelerating classroom learning, graduate research, and collaborative science.
PDRMIP: A Precipitation Driver and Response Model Intercomparison Project—Protocol and Preliminary Results
Authors: Myhre G. , Forster P. M. , Samset B. H. , Hodnebrog Ø. , Sillmann J. , Aalbergsjø S. G. , Andrews T. , Boucher O. , Faluvegi G. , Fläschner D. , Iversen T. , Kasoar M. , Kharin V. , Kirkevåg A. , Lamarque J.-F. , Olivié D. , Richardson T. B. , Shindell D. , Shine K. P. , Stjern C. W. , Takemura T. , Voulgarakis A. , Zwiers F.
Published: October 2016

As the global temperature increases with changing climate, precipitation rates and patterns are affected through a wide range of physical mechanisms. The globally averaged intensity of extreme precipitation also changes more rapidly than the globally averaged precipitation rate. While some aspects of the regional variation in precipitation predicted by climate models appear robust, there is still a large degree of intermodel differences unaccounted for. Individual drivers of climate change initially alter the energy budget of the atmosphere, leading to distinct rapid adjustments involving changes in precipitation. Differences in how these rapid adjustment processes manifest themselves within models are likely to explain a large fraction of the present model spread and better quantifications are needed to improve precipitation predictions. Here, the authors introduce the Precipitation Driver and Response Model Intercomparison Project (PDRMIP), where a set of idealized experiments designed to understand the role of different climate forcing mechanisms were performed by a large set of climate models. PDRMIP focuses on understanding how precipitation changes relating to rapid adjustments and slower responses to climate forcings are represented across models. Initial results show that rapid adjustments account for large regional differences in hydrological sensitivity across multiple drivers. The PDRMIP results are expected to dramatically improve understanding of the causes of the present diversity in future climate projections.
Persistence and Predictions of the Remarkable Warm Anomaly in the Northeastern Pacific Ocean during 2014–16
Authors: Hu Zeng-Zhen , Kumar Arun , Jha Bhaskar , Zhu Jieshun , Huang Bohua
Published: October 2016

In this work, the evolution and prediction of the persistent and remarkable warm sea surface temperature anomaly (SSTA) in the northeastern Pacific during October 2013–June 2016 are examined. Based on experiments with an atmospheric model, the possible contribution of SSTAs in different ocean basins to the atmospheric circulation anomalies is identified. Further, through verifying the real-time forecasts, current capabilities in predicting such an extreme warm event with a state-of-the-art coupled general circulation model are assessed.

During the long-lasting warm event, there were two warm maxima in the area-averaged SSTA around January 2014 and July 2015, respectively. The warm anomaly originated at the oceanic surface and propagated downward and reached about 300 m. Model experiments forced by observed SST suggest that the long persistence of the atmospheric anomalies in the northeastern Pacific as a whole may be partially explained by SST forcing, particularly in the tropical Pacific Ocean associated with a persistent warm SSTA in 2014/15 and an extremely strong El Niño in 2015/16, via its influence on atmospheric circulation over the North Pacific. Nevertheless, it was a challenge to predict the evolution of this warm event, especially for its growth. That is consistent with the fact that the SSTAs in extratropical oceans are largely a consequence of unpredictable atmospheric variability.
Large-Scale Controls on Extreme Precipitation
Authors: Loriaux Jessica M. , Lenderink Geert , Siebesma A. Pier
Published: October 2016

Large-eddy simulations with strong lateral forcing representative of precipitation over the Netherlands are performed to investigate the influence of stability, relative humidity (RH), and moisture convergence on precipitation. Furthermore, a simple climate perturbation is applied to analyze the precipitation response to increasing temperatures. Precipitation is decomposed to distinguish between processes affecting the precipitating area and the precipitation intensity. It is shown that amplification of the moisture convergence and destabilization of the atmosphere both lead to an increase in precipitation, but on account of different effects: atmospheric stability mainly influences the precipitation intensity, whereas the moisture convergence mainly controls the precipitation area fraction. Extreme precipitation intensities show qualitatively similar sensitivities to atmospheric stability and moisture convergence. Precipitation increases with RH due to an increase in area fraction, despite a decrease in intensity. The precipitation response to the climate perturbation shows a stronger response for the precipitation intensity than the overall precipitation, with no clear dependency on changes in atmospheric stability, moisture convergence, and relative humidity.
Evaluation and Validation of GPM Dual-Frequency Classification Module after Launch
Authors: Le Minda , Chandrasekar V. , Biswas Sounak
Published: October 2016

The Dual-Frequency Precipitation Radar (DPR) on board the Global Precipitation Measurement (GPM) Core Observatory has reflectivity measurements at two different frequencies: Ku and Ka bands. The dual-frequency ratio from the measurements has been used to perform rain type classification and microphysics retrieval in the current DPR level 2 algorithm. The dual-frequency classification module is a new module in the GPM level 2 algorithm. The module performs rain type classification and melting region detection using the vertical profile of the dual-frequency ratio. This paper presents an evaluation of the performance of the GPM dual-frequency classification module after launch. The evaluation process includes a comparison between the dual-frequency classification results and the TRMM legacy single-frequency results, as well as validation with ground radars.
Improving the Altimeter-Derived Surface Currents Using High-Resolution Sea Surface Temperature Data: A Feasability Study Based on Model Outputs
Authors: Rio M.-H. , Santoleri R. , Bourdalle-Badie R. , Griffa A. , Piterbarg L. , Taburet G.
Published: October 2016

Accurate knowledge of ocean surface currents at high spatial and temporal resolutions is crucial for a gamut of applications. The altimeter observing system, by providing repeated global measurements of the sea surface height, has been by far the most exploited system to estimate ocean surface currents over the past 20 years. However, it neither permits the observation of currents moving away from the geostrophic balance nor is it capable of resolving the shortest spatial and temporal scales of the currents. Therefore, to overcome these limitations, in this study the ways in which the high-spatial-resolution and high-temporal-resolution information from sea surface temperature (SST) images can improve the altimeter current estimates are investigated. The method involves inverting the SST evolution equation for the velocity by prescribing the source and sink terms and employing the altimeter currents as the large-scale background flow. The method feasibility is tested using modeled data from the Mercator Ocean system. This study shows that the methodology may improve the altimeter velocities at spatial scales not resolved by the altimeter system (i.e., below 150 km) but also at larger scales, where the geostrophic equilibrium might not be the unique or dominant process of the ocean circulation. In particular, the major improvements (more than 30% on the meridional component) are obtained in the equatorial band, where the geostrophic assumption is not valid. Finally, the main issues anticipated when this method is applied using real datasets are investigated and discussed.
Rock-physics diagnostics of a turbidite oil reservoir offshore northwest Australia
Authors: Arévalo-López Humberto S. , Dvorkin Jack P.
Published: October 2016

Interpreting seismic data for petrophysical rock properties requires a rock-physics model that links the petrophysical rock properties to the elastic properties, such as velocity and impedance. Such a model can only be established from controlled experiments in which both groups of rock properties are measured on the same samples. A prolific source of such data is wellbore measurements. We use data from four wells drilled through a clastic offshore oil reservoir to perform rock-physics diagnostics, i.e., to find a theoretical rock-physics model that quantitatively explains the measurements. Using the model, we correct questionable well curves. Moreover, a crucial purpose of rock-physics diagnostics is to go beyond the settings represented in the wells and understand the seismic signatures of rock properties varying in a wider range via forward seismic modeling. With this goal in mind, we use our model to generate synthetic seismic gathers from perturbational modeling to address “what-if” scenarios not present in the wells.
Assessment of different approaches to rock-physics modeling: A case study from offshore Nile Delta
Authors: Aleardi Mattia , Ciabarri Fabio
Published: October 2016

The estimation of a reliable rock-physics model (RPM) plays a crucial role in reservoir characterization studies. We assess different methods in deriving a reliable RPM that will be used in conjunction with amplitude-versus-angle inversion for the characterization of a clastic reservoir located in offshore Nile Delta. The reservoir zone is located in gas-saturated sand channels surrounded by shale sequences within a depth interval ranging between 2.3 and 2.7 km. One theoretical and three empirical approaches to derive a RPM are analyzed: The theoretical RPM is established using the well-known rock-physics equations valid for granular materials, whereas the empirical RPMs are derived using one multilinear stepwise regression and two nonlinear regression procedures based on neural networks (NNs) and genetic algorithms (GAs). A proper calibration and validation of the derived RPMs is conducted by using the extensive log suite of four existing wells drilled over an area of [Formula: see text]. For the investigated reservoir interval and for the encasing shales, all the analyzed methods give a final RPM that is able to reliably predict the elastic attributes (P-wave velocity, S-wave velocity, and density) from the petrophysical properties of interest (porosity, water saturation, and shaliness). Among the empirical approaches, the RPM predicted by the multilinear regression is characterized by a prediction capability very similar to the RPMs predicted by the nonlinear GA method, thus demonstrating that in the investigated zone, the relation linking the petrophysical properties to the elastic attributes can be conveniently described by a multilinear model. Differently, the NN method seems to be affected by the overfitting problem that produces a RPM with a lower prediction capability than the RPMs estimated by the other methods. The theoretical method yields predictions of elastic properties very similar to those produced by multilinear regression.
Surface wave surveying for near-surface site characterization in the East San Francisco Bay Area, California
Authors: Craig Mitchell , Hayashi Koichi
Published: October 2016

Seismic surface wave methods are effective tools for estimating S-wave velocity in urban areas for near-surface site characterization and geologic hazard assessment. A surface wave survey can provide quantitative site-specific measurement of physical properties needed for the design of earthquake-resistant structures. We successfully used a combined active and passive seismic surface wave method to estimate the S-wave velocity in the upper 30 m at sites with a range of geologic conditions. At five of the six sites, multichannel analysis of surface waves (MASW) and microtremor array method (MAM) methods were used. The MAM method could not be used at one site due to insufficient ambient noise. Data from the active method (MASW) contained higher frequencies that contributed to higher resolution of the near-surface zone, whereas passive data (MAM) contained lower frequencies that provided deeper penetration. Phase velocities from the two methods were in good agreement in the frequency range where they overlapped. Surface wave dispersion curves from the two methods were used to prepare an initial velocity model, and a nonlinear inversion was performed to obtain an improved velocity-depth profile. The use of a multimethod data set provided greater confidence in velocity measurements. The six sites of this study may be classified as belonging to two main groups based on S-wave velocities and geologic materials. Two sites are located in the East Bay Hills on Mesozoic bedrock, and four sites are located on Holocene sedimentary units. The highest [Formula: see text] was [Formula: see text] (class C), at a site with fractured and weathered bedrock exposed in a geotechnical trench at 1–2 m depth. The four sites on Holocene sedimentary units have [Formula: see text] values ranging from 207 to [Formula: see text] (class D).
An offshore Gabon full-waveform inversion case study
Authors: Xiao Bingmu , Kotova Nadezhda , Bretherton Samuel , Ratcliffe Andrew , Duval Gregor , Page Chris , Pape Owen
Published: October 2016

Velocity model building is one of the most difficult aspects of the seismic processing sequence. But it is also one of the most important: an accurate earth model allows an accurate migrated image to be formed, which allows the geologist a better chance at an accurate interpretation of the area. In addition, the velocity model itself can provide complementary information about the geology and geophysics of the region. Full-waveform inversion (FWI) is a popular, high-end velocity model-building tool that can generate high-resolution earth models, especially in regions of the model probed by the transmitted (diving wave) arrivals on the recorded seismic data. The history of the South Gabon Basin is complex, leading to a rich geologic picture today and a very challenging velocity model-building process. We have developed a case study from the offshore Gabon area showing that FWI is able to help with the model-building process, and the resulting velocity model reveals features that improve the migrated image. The application of FWI is made on an extremely large area covering approximately 25,000 [Formula: see text], demonstrating that FWI can be applied to this magnitude of survey in a timely manner. In addition, the detail in the FWI velocity model aids the geologic interpretation by highlighting, among other things, the location of shallow gas pockets, buried channels, and carbonate rafts. The concept of actively using the FWI-derived velocity model to aid the interpretation in areas of complex geology, and/or to identify potential geohazards to avoid in an exploration context, is applicable to many parts of the world.
Structurally constrained impedance inversion
Authors: Hamid Haitham , Pidlisecky Adam
Published: October 2016

In complex geology, the presence of highly dipping structures can complicate impedance inversion. We have developed a structurally constrained inversion in which a computationally well-behaved objective function is minimized subject to structural constraints. This approach allows the objective function to incorporate structural orientation in the form of dips into our inversion algorithm. Our method involves a multitrace impedance inversion and a rotation of an orthogonal system of derivative operators. Local dips used to constrain the derivative operators were estimated from migrated seismic data. In addition to imposing structural constraints on the inversion model, this algorithm allows for the inclusion of a priori knowledge from boreholes. We investigated this algorithm on a complex synthetic 2D model as well as a seismic field data set. We compared the result obtained with this approach with the results from single trace-based inversion and laterally constrained inversion. The inversion carried out using dip information produces a model that has higher resolution that is more geologically realistic compared with other methods.
Two-step joint PP- and PS-wave three-term amplitude-variation with offset inversion
Authors: Du Qizhen , Zhang Bo , Meng Xianjun , Guo Chengfeng , Chen Gang , Huo Guodong
Published: October 2016

Three-term amplitude-variation with offset (AVO) inversion generally suffers from instability when there is limited prior geologic or petrophysical constraints. Two-term AVO inversion shows higher instability compared with three-term AVO inversion. However, density, which is important in the fluid-type estimation, cannot be recovered from two-term AVO inversion. To reliably predict the P- and S-waves and density, we have developed a robust two-step joint PP- and PS-wave three-term AVO-inversion method. Our inversion workflow consists of two steps. The first step is to estimate the P- and S-wave reﬂectivities using Stewart’s joint two-term PP- and PS-AVO inversion. The second step is to treat the P-wave reflectivity obtained from the first step as the prior constraint to remove the P-wave velocity related-term from the three-term Aki-Richards PP-wave approximated reflection coefficient equation, and then the reduced PP-wave reflection coefficient equation is combined with the PS-wave reflection coefficient equation to estimate the S-wave and density reﬂectivities. We determined the effectiveness of our method by first applying it to synthetic models and then to field data. We also analyzed the condition number of the coefficient matrix to illustrate the stability of the proposed method. The estimated results using proposed method are superior to those obtained from three-term AVO inversion.