bluuebunny/crossref_metadata_2025 huggingface dataset:
Klebsiella pneumoniae Major Porins OmpK35 and OmpK36 Allow More Efficient Diffusion of β-Lactams than Their Escherichia coli Homologs OmpF and OmpC
Authors: Sugawara Etsuko , Kojima Seiji , Nikaido Hiroshi
Published: September 2016

Klebsiella pneumoniae, one of the most important nosocomial pathogens, is becoming a major problem in health care because of its resistance to multiple antibiotics, including cephalosporins of the latest generation and, more recently, even carbapenems. This is largely due to the spread of plasmid-encoded extended-spectrum β-lactamases. However, antimicrobial agents must first penetrate the outer membrane barrier in order to reach their targets, and hydrophilic and charged β-lactams presumably diffuse through the porin channels. Unfortunately, the properties ofK. pneumoniaeporin channels are largely unknown. In this study, we made clean deletions ofK. pneumoniaeporin genesompK35andompK36and examined the antibiotic susceptibilities and diffusion rates of β-lactams. The results showed that OmpK35 and OmpK36 produced larger more permeable channels than theirEscherichia colihomologs OmpF and OmpC; OmpK35 especially produced a diffusion channel of remarkably high permeability toward lipophilic (benzylpenicillin) and large (cefepime) compounds. These results were also confirmed by expressing various porins in anE. colistrain lacking major porins and the major multidrug efflux pump AcrAB. Our data explain why the development of drug resistance inK. pneumoniaeis so often accompanied by the mutational loss of its porins, especially OmpK35, in addition to the various plasmid-carried genes of antibiotic resistance, because even hydrolysis by β-lactamases becomes inefficient in producing high levels of resistance if the bacterium continues to allow a rapid influx of β-lactams through its wide porin channels.

IMPORTANCEIn Gram-negative bacteria, drugs must first enter the outer membrane, usually through porin channels. Thus, the quantitative examination of influx rates is essential for the assessment of resistance mechanisms, yet no such studies exist for a very important nosocomial pathogen,Klebsiella pneumoniae. We found that the larger channel porin of this organism, OmpK35, produces a significantly larger channel than itsEscherichia colihomolog, OmpF. This makes unmodifiedK. pneumoniaestrains more susceptible to relatively large antibiotics, such as the third- and fourth-generation cephalosporins. Also, even the acquisition of powerful β-lactamases is not likely to make them fully resistant in the presence of such an effective influx process, explaining why so many clinical isolates of this organism lack porins.
Zygomatic haematoma in an 11-month-old helps diagnose retropharyngeal abscess, with concurrent tonsillitis and subsequent infant tonsillectomy
Authors: Collis David H , Sanu Ameeth
Published: September 2016

An 11-month-old boy presented with a 2-day history of non-specific symptoms and a zygomatic haematoma. With aetiology uncertain after admission clerking and blood tests, a CT head scan was arranged for suspected traumatic injury and revealed a retropharyngeal abscess (RPA) with significant airway narrowing in the transverse plane. The patient received urgent intraoral abscess drainage and bilateral tonsillectomy in theatre. This case highlights the need for a high index of suspicion regarding RPAs. These abscesses have potentially fatal sequelae and are difficult to diagnose in the infant paediatric population.
Pseudoappendicitis: abdominal pain arising from thoracic spine dysfunction—a forgotten entity and a reminder of an important clinical lesson
Authors: Garo-Falides Basil , Wainwright Thomas William
Published: September 2016

Acute or chronic abdominal pain can be mimicked by thoracic spine dysfunction. However, it is comparatively rare and there is frequently a delay in its diagnosis that may lead to unnecessary surgery, or the patient's symptoms being undiagnosed or labelled psychosomatic. The failure to associate thoracic spine dysfunction with abdominal pain persists, despite it being first recognised over 80 years ago. 2 recent such cases are presented. The clinical presentation and diagnostic tests are described, with clear explanation of the treatment and outcome. The case for including the thoracic spine examination in the assessment of patients presenting with acute abdominal or postappendectomy pain that is of unexplained origin is made.
Apixaban-induced liver injury
Authors: Clarke Sherri-Anne , Alsaad Ali A , Mack Anwar , Phillips Michael B
Published: September 2016

An 81-year-old woman with well-controlled hypertension presented to the emergency department with new-onset atrial fibrillation with rapid ventricular response. Treatment for atrial fibrillation was initiated, including rate control and anticoagulation with 5 mg of apixaban two times per day for primary stroke prophylaxis. Three days after initiation of apixaban, the patient noted new-onset abdominal pain, worsening shortness of breath and weakness. Laboratory results showed elevated liver enzymes. Workup for elevated transaminase did not reveal any underlying infectious or autoimmune process. Apixaban, a probable cause for the hepatocellular injury, was discontinued and replaced with intravenous unfractionated heparin to bridge anticoagulation with warfarin. The patient's symptoms resolved as her transaminases improved by discontinuation of apixaban. We illustrate this case of drug-induced hepatotoxicity secondary to treatment with apixaban. It is important for physicians to be aware of this rare adverse effect caused by a widely used novel oral anticoagulant.
Immune pancytopenia after chemotherapy in a patient with diffuse large B-cell lymphoma
Authors: Nagashima Kazuyo , Tanaka Hiroaki , Nagai Yurie , Sugita Yasumasa
Published: September 2016

During treatment for malignant lymphoma, cytopenia can develop for several reasons. In the treatment of cytopenia, various possibilities should be considered because inadequate treatment causes exacerbation of cytopenia and can lead to fatal conditions, such as infection and bleeding. Herein, we describe immune pancytopenia 3 months after the last exposure to chemotherapy in a patient with diffuse large B-cell lymphoma (DLBCL). She suffered from severe pancytopenia after two courses of rituximab and bendamustine therapy for a second relapse of DLBCL. Immune pancytopenia was diagnosed with bone marrow tests and the presence of autoantibodies; it promptly resolved after initiation of prednisolone therapy. Clinicians should be aware of immune cytopenia and monitor for it carefully, even if patients have already finished chemotherapy treatment.
Incentivising practice with take-home laparoscopic simulators in two UK Core Surgical Training programmes
Authors: Nicol Laura G , Walker Kenneth G , Cleland Jennifer , Partridge Roland , Moug Susan J
Published: September 2016

Introduction

Practice using simulators has been validated as a mean for surgical trainees to improve basic laparoscopic skills and free their attention for higher cognitive functions. However, mere provision of equipment does not result in frequent practice. This study assesses one approach to incentivising practice within core surgical training programmes and leads to further recommendations.

Methods

30 core surgical trainees (CST) starting laparoscopic-based specialties were recruited from East and West of Scotland CST programmes and given take-home laparoscopic simulators, with six training modules. Attainment of target metric scores generated an eCertificate, to be rewarded by progression in the live theatre. Questionnaires assessed confounding variables and explored CSTs’ anxieties about laparoscopy.

Results

27 trainees (90%) agreed to participate (mean age 28 years, range 24–25; 17 males). 13 CSTs (48%) were in the first year of surgical training. 11 (41%) had no previous simulation experience and 7 (32%) CSTs played video games >3 hours/week. 12 of 27 trainees (44%) completed ≥1 task and 7 completed all (26%).

Performances improved in some participants, but overall engagement with the programme was poor. Reasons given included poor internet connectivity, busy rotations and examinations. CSTs who engaged in the study significantly reduced their anxiety (mean 4.96 vs 3.56, p<0.05).

Conclusions

The provision of take-home laparoscopic simulators with accompanying targets did not successfully incentivise CSTs to practise. However, the subgroup who did engage with the project reported performance improvements and significantly reduced anxiety. Proposals to overcome barriers to practising in simulation, including obligatory simulation-based assessments, are discussed.
Dietary sugars versus glucose tablets for first-aid treatment of symptomatic hypoglycaemia in awake patients with diabetes: a systematic review and meta-analysis
Authors: Carlson Jestin N , Schunder-Tatzber Susanne , Neilson Christine J , Hood Natalie
Published: September 2016

Background

While glucose tablets have been advocated for treating symptomatic hypoglycaemia in awake patients, dietary sugars may be more convenient. We performed a systematic review to compare the impact of these treatment options on the relief of symptomatic hypoglycaemia, time to resolution of symptoms, blood glucose levels, complications and hospital length of stay.

Method

We searched PubMed, Embase and the Cochrane Library through 28 June 2016 and assessed the quality of evidence using the Grades of Recommendation, Assessment, Development and Evaluation approach. Reference lists from a subset of the resulting articles were mined for additional, potentially eligible papers. We calculated the risk ratio (RR) of each treatment option for the preselected outcomes of interest.

Results

Of the 1774 identified papers, four studies met the inclusion criteria; three randomised controlled trials totalling 502 hypoglycaemic events treated with dietary sugars and 223 with glucose tablets and one observational study with 13 events treated with dietary sugars and 9 with glucose tablets. The dietary forms of sugar included sucrose, fructose, orange juice, jelly beans, Mentos, cornstarch hydrolysate, Skittles and milk. In the pooled analysis, patients treated with dietary sugars had a lower resolution of symptoms 15 min after treatment compared with glucose tablets (RR 0.89, 95% CI 0.83 to 0.95).

Conclusions

When compared with dietary sugars, glucose tablets result in a higher rate of relief of symptomatic hypoglycaemia 15 min after ingestion and should be considered first, if available, when treating symptomatic hypoglycaemia in awake patients.
Social mobility and inflammatory and metabolic markers at older ages: the English Longitudinal Study of Ageing
Authors: Na-Ek Nat , Demakakos Panayotes
Published: September 2016

Background

Since our knowledge of the associations between socioeconomic position (SEP) over the life course and inflammatory and metabolic markers, which are excellent predictors of cardiovascular disease, remains limited, we examined the association between social mobility over the life course and these markers at older ages.

Methods

Our study used cross-sectionally collected data from 6142 participants aged 50 years and older from the English Longitudinal Study of Ageing. We estimated linear and logistic models of the associations between social mobility, using information on childhood and adult SEP, C reactive protein (CRP), fibrinogen, glycated haemoglobin (HbA1c) and high-density lipoprotein (HDL) cholesterol. Our models were gradually adjusted for age, sex, chronic diseases, obesity, physical activity, alcohol consumption, smoking status and depressive symptoms.

Results

Participants who experienced upward social mobility had higher CRP, fibrinogen and HbA1c levels compared with those who had stable high SEP over the life course, but lower compared with those who experienced downward social mobility or had stable low SEP. They also had lower HDL levels compared with those who had stable high SEP or downwardly mobile. Adjustment for covariates partially explained the associations between social mobility and CRP and HDL, and fully explained those between social mobility and fibrinogen and HbA1c.

Conclusions

Social mobility is associated with inflammatory and metabolic markers at older ages with some of the observed associations persisting after accounting for covariates. Upward social mobility appears to partially reverse the damaging effect of childhood social disadvantage on inflammatory profiles in older ages.
Systematic screening for cardiovascular risk at pharmacies
Authors: Rohla Miklos , Haberfeld Heinz , Sinzinger Helmut , Kritz Harald , Tscharre Maximilian , Freynhofer Matthias K , Huber Kurt , Weiss Thomas W
Published: September 2016

Background

Early identification and treatment of cardiovascular risk factors (CVRFs) is essential to prevent excess morbidity, mortality and healthcare-related costs. We sought to investigate whether an active screening programme at pharmacies could identify a significant proportion of patients with previously undetected CVRFs.

Methods and results

Between April and July 2013, 184 pharmacies in Lower Austria enrolled a total of 6800 participants, in whom body mass index (BMI), blood pressure (BP), total cholesterol and blood glucose were measured. Mean age was 58±17 years and 67.8% were women. 21% of men and 16% of women had a BMI≥30 kg/m2. The crude prevalence of diabetes mellitus (DM) was 7%, hypercholesterolaemia was identified in 57%, and 44% had elevated BP. Among fasting individuals (n=1814), DM was found in 18%. In total, 30% were confronted with a CVRF they were previously unaware of, and pharmacists recommended 45% of all participants to actively consult a physician. A first-time diagnosis of a CVRF was most frequent in the age groups between 25 and 64 (32% of participants).

Conclusions

This pharmacy-based approach for cardiovascular risk screening found similar overall prevalences of CVRFs as reported by national surveys, but revealed underdiagnoses, particularly in lower age groups. A previously unknown CVRF was identified in every third individual, frequently prompting the pharmacists to recommend the consultation of a physician. An active screening approach at pharmacies might therefore serve as an effective alternative to the public preventive medical examination, particularly in younger age groups.
Words matter: Reframing exercise is medicine for the general population to optimize motivation and create sustainable behaviour change
Authors: Fortier Michelle , Guérin Eva , Segar Michelle L.
Published: September 2016

Exercise is medicine (EIM) is grounded in strong evidence regarding the benefits of physical activity. Despite the contributions of EIM initiatives worldwide, rates of physical inactivity remain alarmingly high. We propose a reframe of EIM for the general population to improve motivation and foster sustainable behaviour change. We draw on a solid knowledge-base to explain the value of broadening the nomenclature to physical activity and of promoting a message of well-being via enjoyable physical activity.
Parallel Nonnegative Matrix Factorization via Newton Iteration
Authors: Flatz Markus , Vajteršic Marián
Published: September 2016

The goal of Nonnegative Matrix Factorization (NMF) is to represent a large nonnegative matrix in an approximate way as a product of two significantly smaller nonnegative matrices. This paper shows in detail how an NMF algorithm based on Newton iteration can be derived using the general Karush-Kuhn-Tucker (KKT) conditions for first-order optimality. This algorithm is suited for parallel execution on systems with shared memory and also with message passing. Both versions were implemented and tested, delivering satisfactory speedup results.
Gauge-invariant extensions of the Proca model in a noncommutative space–time
Authors: Abreu Everton M. C. , Neto Jorge Ananias , Fernandes Rafael L. , Mendes Albert C. R.
Published: September 2016

The gauge invariance analysis of theories described in noncommutative (NC) space–times can lead us to interesting results since noncommutativity is one of the possible paths to investigate quantum effects in classical theories such as general relativity, for example. This theoretical possibility has motivated us to analyze the gauge invariance of the NC version of the Proca model, which is a second-class system, in Dirac’s classification, since its classical formulation (commutative space–time) has its gauge invariance broken thanks to the mass term. To obtain such gauge invariant model, we have used the gauge unfixing method to construct a first-class NC version of the Proca model. We have also questioned if the gauge symmetries of NC theories are affected necessarily or not by the NC parameter. In this way, we have calculated its respective symmetries in a standard way via Poisson brackets.
The Correlation Dimension of a Rectilinear Grid
Authors: ROSENBERG ERIC
Published: September 2016

The correlation dimension dC of a finite network measures how the fraction of nodes at a given distance from a random node scales with the distance. However, there is no standardized formal definition of dC for a network. We consider various possible definitions of dC for a finite unweighted and undirected rectilinear grid in one, two, and three dimensions. We propose a simple “overall slope” definition for dC which yields an exact closed form expression for such grids. We prove that the overall slope definition satisfies two properties that should be satisfied by any definition of the correlation dimension of a network. Lastly, we present a conjecture giving a closed form expression for the overall slope correlation dimension of a finite rectilinear grid in E dimensions, for any positive integer E.
A review and new data on neotectonic evolution of active faults in the Kachchh Basin, Western India: legacy of post-Deccan Trap tectonic inversion
Authors: Maurya D. M. , Chowksey Vikas , Patidar A. K. , Chamyal L. S.
Published: September 2016

The Kachchh Basin, located in Gujarat (India) at the western trailing edge of the Indian plate, comprises several east–west trending seismically active faults. The Kachchh Basin evolved in two major stages. The first is the rift stage, which correlates with the break-up and separation of the Indian plate in the Late Triassic–Early Cretaceous and synrift sedimentation. The second is the post-Deccan Trap inversion stage, when the basin was periodically uplifted along the existing east–west trending intrabasinal master faults: the Katrol Hill Fault, the Kachchh Mainland Fault, the South Wagad Fault, the Gedi Fault and the Island Belt Fault. The inversion of basin was initiated by the onset of a compressive stress regime in response to the collision of the Indian plate with the Eurasian plate in the far north during the Early Eocene. This is shown by the tilting of the Deccan Trap lava flows along with the underlying Mesozoic sequence and the associated intrusive bodies that occupy the core portions of domal and anticlinal flexures bounded by major fault lines. Seismotectonic data on the prolonged aftershock sequence after the 2001 Bhuj earthquake (M
w
7.7) reveal continuous low-to-moderate seismic activity along multiple faults covering a large area, now identified as the Kachchh Seismic Zone. This article reviews the neotectonic perspective of the active faults with the prime objective of delineating the post-Deccan Trap inversion phase of the Kachchh Basin, with an emphasis on neotectonism with regard to modern seismic activity. The datasets presented are primarily field-based neotectonic data from active fault zones that cover aspects of the tectonic geomorphology, Quaternary stratigraphy, near-surface fault traces and the nature of the fault in the shallow subsurface based on ground-penetrating radar studies. We also attempt a comparative neotectonic evaluation of each active fault in the Kachchh Basin and discuss the constraints for evolving a viable neotectonic model of the basin.
Evaluating Shape Representations for Maya Glyph Classification
Authors: Can Gülcan , Odobez Jean-Marc , Gatica-Perez Daniel
Published: September 2016

Shape representations are critical for visual analysis of cultural heritage materials. This article studies two types of shape representations in a bag-of-words-based pipeline to recognize Maya glyphs. The first is a knowledge-driven Histogram of Orientation Shape Context (HOOSC) representation, and the second is a data-driven representation obtained by applying an unsupervised Sparse Autoencoder (SA). In addition to the glyph data, the generalization ability of the descriptors is investigated on a larger-scale sketch dataset. The contributions of this article are four-fold: (1) the evaluation of the performance of a data-driven auto-encoder approach for shape representation; (2) a comparative study of hand-designed HOOSC and data-driven SA; (3) an experimental protocol to assess the effect of the different parameters of both representations; and (4) bridging humanities and computer vision/machine learning for Maya studies, specifically for visual analysis of glyphs. From our experiments, the data-driven representation performs overall in par with the hand-designed representation for similar locality sizes on which the descriptor is computed. We also observe that a larger number of hidden units, the use of average pooling, and a larger training data size in the SA representation all improved the descriptor performance. Additionally, the characteristics of the data and stroke size play an important role in the learned representation.
Automated Verification of Equivalence Properties of Cryptographic Protocols
Authors: Chadha Rohit , Cheval Vincent , Ciobâcă Ştefan , Kremer Steve
Published: September 2016

Indistinguishability properties are essential in formal verification of cryptographic protocols. They are needed to model anonymity properties, strong versions of confidentiality, and resistance against offline guessing attacks. Indistinguishability properties can be conveniently modeled as equivalence properties. We present a novel procedure to verify equivalence properties for a bounded number of sessions of cryptographic protocols. As in the applied pi calculus, our protocol specification language is parametrized by a first-order sorted term signature and an equational theory that allows formalization of algebraic properties of cryptographic primitives. Our procedure is able to verify trace equivalence for determinate cryptographic protocols. On determinate protocols, trace equivalence coincides with observational equivalence, which can therefore be automatically verified for such processes. When protocols are not determinate, our procedure can be used for both under- and over-approximations of trace equivalence, which proved successful on examples. The procedure can handle a large set of cryptographic primitives, namely those whose equational theory is generated by an optimally reducing convergent rewrite system. The procedure is based on a fully abstract modelling of the traces of a bounded number of sessions of the protocols into first-order Horn clauses on which a dedicated resolution procedure is used to decide equivalence properties. We have shown that our procedure terminates for the class of subterm convergent equational theories. Moreover, the procedure has been implemented in a prototype tool Active Knowledge in Security Protocols and has been effectively tested on examples. Some of the examples were outside the scope of existing tools, including checking anonymity of an electronic voting protocol due to Okamoto.
Noncoding RNAs in Cancer Development
Authors: Lin Chao-Po , He Lin
Published: September 2016

It is becoming increasingly clear that a large repertoire of noncoding RNAs (ncRNAs) are actively transcribed from the mammalian genome, regulating diverse cellular processes in development and diseases through a variety of gene regulatory mechanisms. As the most extensively studied ncRNA species, microRNAs (miRNAs) are important components in the oncogene and tumor suppressor network, and have been employed as potential biomarkers, therapeutic reagents, and therapeutic targets for cancer treatment. Other ncRNAs, particularly long noncoding RNAs, also have a profound impact on cancer development, as demonstrated in both mouse and human tumor models. We are only starting to understand the realm of ncRNA biology, and the exact molecular mechanisms governing ncRNA functions remain largely unexplored. With numerous ncRNAs discovered through high-throughput approaches, understanding their functions in malignant transformation will be one of the most exciting challenges in cancer research.
Bunching
Authors: Kleven Henrik Jacobsen
Published: September 2016

Recent years have seen a surge of applied work using bunching approaches, a development that is closely linked to the increased availability of administrative data. These approaches exploit the incentives for bunching created by discontinuities in the slope of choice sets (kinks) or in the level of choice sets (notches) to study the behavior of individuals and firms. Although the bunching approach was originally developed in the context of taxation, it is beginning to find applications in many other areas, such as social security, social insurance, welfare programs, education, regulation, private sector prices, and reference-dependent preferences. This review provides a guide to bunching estimation, discusses its strengths and weaknesses, surveys a range of applications across fields, and considers reasons for the ubiquity of kinks and notches.
Infrequent but Long-Lived Zero Lower Bound Episodes and the Optimal Rate of Inflation
Authors: Dordal i Carreras Marc , Coibion Olivier , Gorodnichenko Yuriy , Wieland Johannes
Published: September 2016

Countries rarely hit the zero lower bound (ZLB) on interest rates, but when they do, these episodes tend to be very long-lived. These two features are difficult to incorporate jointly into macroeconomic models using typical representations of shock processes. We introduce a regime-switching representation of risk premium shocks into an otherwise standard New Keynesian model to generate a realistic distribution of ZLB durations. We discuss what different calibrations of this model imply for optimal inflation rates.
The Plant Microbiota: Systems-Level Insights and Perspectives
Authors: Müller Daniel B. , Vogel Christine , Bai Yang , Vorholt Julia A.
Published: September 2016

Plants do not grow as axenic organisms in nature, but host a diverse community of microorganisms, termed the plant microbiota. There is an increasing awareness that the plant microbiota plays a role in plant growth and can provide protection from invading pathogens. Apart from intense research on crop plants, Arabidopsis is emerging as a valuable model system to investigate the drivers shaping stable bacterial communities on leaves and roots and as a tool to decipher the intricate relationship among the host and its colonizing microorganisms. Gnotobiotic experimental systems help establish causal relationships between plant and microbiota genotypes and phenotypes and test hypotheses on biotic and abiotic perturbations in a systematic way. We highlight major recent findings in plant microbiota research using comparative community profiling and omics analyses, and discuss these approaches in light of community establishment and beneficial traits like nutrient acquisition and plant health.
Identifying Pathways Between Socioeconomic Status and Language Development
Authors: Pace Amy , Luo Rufan , Hirsh-Pasek Kathy , Golinkoff Roberta Michnick
Published: September 2016

Children from low-income backgrounds consistently perform below their more advantaged peers on standardized measures of language ability, setting long-term trajectories that translate into gaps in academic achievement. Our primary goals in this review are to describe how and why this is so, in order to focus attention on ways to enrich early language experiences across socioeconomic strata. We first review the literature on the relation between socioeconomic status (SES) and language ability across domains in early childhood. We then identify three potential pathways by which SES might influence language development—child characteristics, parent–child interaction, and availability of learning resources—recognizing the complicated interaction between the child's own language learning skill and his/her environmental support. Finally, we review interventions that target these three pathways with an eye toward best practice. Future research should focus on the diversity of contexts in which children acquire language and adopt methods of language measurement that are sensitive to cultural variation.
Learning from Errors
Authors: Metcalfe Janet
Published: September 2016

Although error avoidance during learning appears to be the rule in American classrooms, laboratory studies suggest that it may be a counterproductive strategy, at least for neurologically typical students. Experimental investigations indicate that errorful learning followed by corrective feedback is beneficial to learning. Interestingly, the beneficial effects are particularly salient when individuals strongly believe that their error is correct: Errors committed with high confidence are corrected more readily than low-confidence errors. Corrective feedback, including analysis of the reasoning leading up to the mistake, is crucial. Aside from the direct benefit to learners, teachers gain valuable information from errors, and error tolerance encourages students’ active, exploratory, generative engagement. If the goal is optimal performance in high-stakes situations, it may be worthwhile to allow and even encourage students to commit and correct errors while they are in low-stakes learning situations rather than to assiduously avoid errors at all costs.
Pyroshock Prediction of Ridge-Cut Explosive Bolts Using Hydrocodes
Authors: Lee Juho , Hwang Dae-Hyun , Jang Jae-Kyeong , Kim Dong-Jin , Lee YeungJo , Lee Jung-Ryul , Han Jae-Hung
Published: September 2016

Pyrotechnic release devices such as explosive bolts are prevalent for many applications due to their merits: high reliability, high power-to-weight ratio, reasonable cost, and more. However, pyroshock generated by an explosive event can cause failures in electric components. Although pyroshock propagations are relatively well understood through many numerical and experimental studies, the prediction of pyroshock generation is still a very difficult problem. This study proposes a numerical method for predicting the pyroshock of a ridge-cut explosive bolt using a commercial hydrocode (ANSYS AUTODYN). A numerical model is established by integrating fluid-structure interaction and complex material models for high explosives and metals, including high explosive detonation, shock wave transmission and propagation, and stress wave propagation. To verify the proposed numerical scheme, pyroshock measurement experiments of the ridge-cut explosive bolts with two types of surrounding structures are performed using laser Doppler vibrometers (LDVs). The numerical analysis results provide accurate prediction in both the time (acceleration) and frequency domains (maximax shock response spectra). In maximax shock response spectra, the peaks due to vibration modes of the structures are observed in both the experimental and numerical results. The numerical analysis also helps to identify the pyroshock generation source and the propagation routes.
Intelligent Analysis Method of Gear Faults Based on FRWT and SVM
Authors: Chen Hongfang , Sun Yanqiang , Shi Zhaoyao , Lin Jiachun
Published: September 2016

An intelligent analysis method for gear faults based on fractional wavelet transform (FRWT) and support vector machine (SVM) is proposed. Based on this method, FRWT is used to eliminate noise from the gear vibration signal, and the vibration signal after noise elimination is carried thought wavelet packet decomposition and reconstruction. A sequence corresponding to the signal is constructed consisting of the module with the highest level wavelet coefficients after decomposition and feature vectors corresponding to the energy sequence which were obtained by calculation. Then, a particle optimization method is used to optimize SVM parameters, and the feature vectors as training samples are input into SVM for training while the test samples are input for fault recognition. Experimental results show that the gear fault analysis method proposed in this paper is able to effectively extract the weak fault signal. The accuracy rate for identification of the type of gear fault reached 96.7%.
Dynamic Tracking Human Mesenchymal Stem Cells Tropism following Smoke Inhalation Injury in NOD/SCID Mice
Authors: Song MeiJuan , Lv Qi , Zhang XiuWei , Cao Juan , Sun ShuLi , Xiao PeiXin , Hou ShiKe , Ding Hui , Liu ZiQuan , Dong WenLong , Wang JinQiang , Wang Xue , Sun ZhiGuang , Tian Man , Fan HaoJun
Published: September 2016

Multiple preclinical evidences have supported the potential value of mesenchymal stem cells (MSCs) for treatment of acute lung injury (ALI). However, few studies focus on the dynamic tropism of MSCs in animals with acute lung injury. In this study, we track systemically transplanted human bone marrow‐derived mesenchymal stem cells (hBMSCs) in NOD/SCID mice with smoke inhalation injury (SII) through bioluminescence imaging (BLI). The results showed that hBMSCs systemically delivered into healthy NOD/SCID mouse initially reside in the lungs and then partially translocate to the abdomen after 24 h. Compared with the uninjured control group treated with hBMSCs, higher numbers of hBMSCs were found in the lungs of the SII NOD/SCID mice. In both the uninjured and SII mice, the BLI signals in the lungs steadily decreased over time and disappeared by 5 days after treatment. hBMSCs significantly attenuated lung injury, elevated the levels of KGF, decreased the levels of TNF‐α in BALF, and inhibited inflammatory cell infiltration in the mice with SII. In conclusion, our findings demonstrated that more systemically infused hBMSCs localized to the lungs in mice with SII. hBMSC xenografts repaired smoke inhalation‐induced lung injury in mice. This repair was maybe due to the effect of anti‐inflammatory and secreting KGF of hMSCs but not associated with the differentiation of the hBMSCs into alveolar epithelial cells.
Effect of Removal of Enamel on Rebonding Strength of Resin Composite to Enamel
Authors: Kilponen L. , Lassila L. , Tolvanen M. , Varrela J. , Vallittu P. K.
Published: September 2016

Objective. To examine the effect of removing the surface layer of enamel on the rebonding strength of resin composite.Methods. Teeth in four groups (n=10) were etched, a small amount of resin composite was bonded and debonded, then specimens in three groups were ground for different lengths of time (10 s, 20 s, 30 s) to remove an increasing amount of enamel, one group was left untouched. The teeth were bonded again and the bond strengths of 1st and 2nd bonding were compared and analysed against the amount of enamel loss in different groups (7 µm (±2); 12 µm (±1); 16 µm (±3)). Specimens were examined with SEM and by noncontacting optical profilometer.Results. Although results indicated higher rebonding strength with increasing enamel removal ANOVA showed low statistical differences between the groups (p>0.05). However, values between first bonding and rebonding strengths differed significantly (p<0.05) in the group that was not ground. SEM revealed that enamel-surfaces that were ground after debonding etched well, compared to the surfaces that still contained adhesive remnants.Conclusions. Removal of small amount of enamel refreshed the surface for rebonding. Rebonding strengths without grinding the surface before bonding were lower than bond strength to intact enamel.
Advances in Engineered Liver Models for Investigating Drug-Induced Liver Injury
Authors: Lin Christine , Khetani Salman R.
Published: September 2016

Drug-induced liver injury (DILI) is a major cause of drug attrition. Testing drugs on human liver models is essential to mitigate the risk of clinical DILI since animal studies do not always suffice due to species-specific differences in liver pathways. While primary human hepatocytes (PHHs) can be cultured on extracellular matrix proteins, a rapid decline in functions leads to low sensitivity (<50%) in DILI prediction. Semiconductor-driven engineering tools now allow precise control over the hepatocyte microenvironment to enhance and stabilize phenotypic functions. The latest platforms coculture PHHs with stromal cells to achieve hepatic stability and enable crosstalk between the various liver cell types towards capturing complex cellular mechanisms in DILI. The recent introduction of induced pluripotent stem cell-derived human hepatocyte-like cells can potentially allow a better understanding of interindividual differences in idiosyncratic DILI. Liver models are also being coupled to other tissue models via microfluidic perfusion to study the intertissue crosstalk upon drug exposure as in a live organism. Here, we review the major advances being made in the engineering of liver models and readouts as they pertain to DILI investigations. We anticipate that engineered human liver models will reduce drug attrition, animal usage, and cases of DILI in humans.
Rapid and Quantitative Detection ofLeifsonia xylisubsp.xyliin Sugarcane Stalk Juice Using a Real-Time Fluorescent (TaqMan) PCR Assay
Authors: Fu Hua-Ying , Sun Sheng-Ren , Wang Jin-Da , Ahmad Kashif , Wang Heng-Bo , Chen Ru-Kai , Gao San-Ji
Published: September 2016

Ratoon stunting disease (RSD) of sugarcane, one of the most important diseases seriously affecting the productivity of sugarcane crops, was caused by the bacterial agentLeifsonia xylisubsp.xyli(Lxx). A TaqMan probe-based real-time quantitative polymerase chain reaction (qPCR) assay was established in this study for the quantification ofLxxdetection in sugarcane stalk juice. A pair of PCR primers (Pat1-QF/Pat1-QR) and a fluorogenic probe (Pat1-QP) targeting thePart1gene ofLxxwere used for the qPCR assay. The assay had a detection limit of 100 copies of plasmid DNA and 100 fg ofLxxgenomic DNA, which was 100-fold more sensitive than the conventional PCR. Fifty (28.7%) of 174 stalk juice samples from two field trials were tested to be positive by qPCR assay, whereas, by conventional PCR, only 12.1% (21/174) were tested to be positive with a published primer pair CxxITSf#5/CxxITSr#5 and 15.5% (27/174) were tested to be positive with a newly designed primer pair Pat1-F2/Pat1-R2. The new qPCR assay can be used as an alternative to current diagnostic methods forLxx, especially when dealing with certificating a large number of healthy cane seedlings and determining disease incidence accurately in commercial fields.
Vibration Signal Forecasting on Rotating Machinery by means of Signal Decomposition and Neurofuzzy Modeling
Authors: Zurita-Millán Daniel , Delgado-Prieto Miguel , Saucedo-Dorantes Juan José , Cariño-Corrales Jesus Adolfo , Osornio-Rios Roque A. , Ortega-Redondo Juan Antonio , Romero-Troncoso Rene de J.
Published: September 2016

Vibration monitoring plays a key role in the industrial machinery reliability since it allows enhancing the performance of the machinery under supervision through the detection of failure modes. Thus, vibration monitoring schemes that give information regarding future condition, that is, prognosis approaches, are of growing interest for the scientific and industrial communities. This work proposes a vibration signal prognosis methodology, applied to a rotating electromechanical system and its associated kinematic chain. The method combines the adaptability of neurofuzzy modeling with a signal decomposition strategy to model the patterns of the vibrations signal under different fault scenarios. The model tuning is performed by means of Genetic Algorithms along with a correlation based interval selection procedure. The performance and effectiveness of the proposed method are validated experimentally with an electromechanical test bench containing a kinematic chain. The results of the study indicate the suitability of the method for vibration forecasting in complex electromechanical systems and their associated kinematic chains.
Damping Parameters Identification of Cabin Suspension System for Heavy Duty Truck Based on Curve Fitting
Authors: Zhao Leilei , Zhou Changcheng , Yu Yuewei
Published: September 2016

During the dynamic simulation of cabin system, the damping parameters values of cabin suspension are the key factors. In previous work, for obtaining all the parameters of the cabin system of trucks for long distance transport, a parameters identification model was built by minimizing the error of the root-mean-square acceleration between the tested and the measured. However, the identification precision is not high. In this paper, according to the real cabin system of a heavy duty truck for short distance transport, a 3-DOF model of cabin system was built. Based on curve fitting method, a new identification model for damping parameters was established. At last, the bench test was done and the comparisons were conducted among the tested values, the values identified by the method built in this work, and those obtained by the method built in previous work. The results show that the model built and the method proposed are feasible, and the identification precision is higher than the previous work.
Mesenchymal Stem Cells Subpopulations: Application for Orthopedic Regenerative Medicine
Authors: Pérez-Silos Vanessa , Camacho-Morales Alberto , Fuentes-Mera Lizeth
Published: September 2016

Research on mesenchymal stem cells (MSCs) continues to progress rapidly. Nevertheless, the field faces several challenges, such as inherent cell heterogeneity and the absence of unique MSCs markers. Due to MSCs’ ability to differentiate into multiple tissues, these cells represent a promising tool for new cell‐based therapies. However, for tissue engineering applications, it is critical to start with a well‐defined cell population. Additionally, evidence that MSCs subpopulations may also feature distinct characteristics and regeneration potential has arisen. In this report, we present an overview of the identification of MSCs based on the expression of several surface markers and their current tissue sources. We review the use of MSCs subpopulations in recent years and the main methodologies that have addressed their isolation, and we emphasize the most‐used surface markers for selection, isolation, and characterization. Next, we discuss the osteogenic and chondrogenic differentiation from MSCs subpopulations. We conclude that MSCs subpopulation selection is not a minor concern because each subpopulation has particular potential for promoting the differentiation into osteoblasts and chondrocytes. The accurate selection of the subpopulation advances possibilities suitable for preclinical and clinical studies and determines the safest and most efficacious regeneration process.
Geolocation of a Known Altitude Target Using TDOA and GROA in the Presence of Receiver Location Uncertainty
Authors: Deng Bing , Yang Le , Sun Zheng Bo , Peng Hua Feng
Published: September 2016

This paper considers the problem of geolocating a target on the Earth surface using the target signal time difference of arrival (TDOA) and gain ratio of arrival (GROA) measurements when the receiver positions are subject to random errors. The geolocation Cramer-Rao lower bound (CRLB) is derived and the performance improvement due to the use of target altitude information is quantified. An algebraic geolocation solution is developed and its approximate efficiency under small Gaussian noise is established analytically. Its sensitivity to the target altitude error is also studied. Simulations justify the validity of the theoretical developments and illustrate the good performance of the proposed geolocation method.
Algorithm Indicating Moment of P-Wave Arrival Based on Second-Moment Characteristic
Authors: Sokolowski Jakub , Obuchowski Jakub , Zimroz Radoslaw , Wylomanska Agnieszka , Koziarz Eugeniusz
Published: September 2016

The moment of P-wave arrival can provide us with many information about the nature of a seismic event. Without adequate knowledge regarding the onset moment, many properties of the events related to location, polarization of P-wave, and so forth are impossible to receive. In order to save time required to indicate P-wave arrival moment manually, one can benefit from automatic picking algorithms. In this paper two algorithms based on a method finding a regime switch point are applied to seismic event data in order to find P-wave arrival time. The algorithms are based on signals transformed via a basic transform rather than on raw recordings. They involve partitioning the transformed signal into two separate series and fitting logarithm function to the first subset (which corresponds to pure noise and therefore it is considered stationary), exponent or power function to the second subset (which corresponds to nonstationary seismic event), and finding the point at which these functions best fit the statistic in terms of sum of squared errors. Effectiveness of the algorithms is tested on seismic data acquired from O/ZG “Rudna” underground copper ore mine with moments of P-wave arrival initially picked by broadly known STA/LTA algorithm and then corrected by seismic station specialists. The results of proposed algorithms are compared to those obtained using STA/LTA.
Inverse Strategies for Identifying the Parameters of Constitutive Laws of Metal Sheets
Authors: Prates P. A. , Pereira A. F. G. , Sakharova N. A. , Oliveira M. C. , Fernandes J. V.
Published: September 2016

This article is a review regarding recently developed inverse strategies coupled with finite element simulations for the identification of the parameters of constitutive laws that describe the plastic behaviour of metal sheets. It highlights that the identification procedure is dictated by the loading conditions, the geometry of the sample, the type of experimental results selected for the analysis, the cost function, and optimization algorithm used. Also, the type of constitutive law (isotropic and/or kinematic hardening laws and/or anisotropic yield criterion), whose parameters are intended to be identified, affects the whole identification procedure.
Accelerometer Sensor Specifications to Predict Hydrocarbon Using Passive Seismic Technique
Authors: Md Khir M. H. , Kumar Atul , Wan Yusoff Wan Ismail
Published: September 2016

The ambient seismic ground noise has been investigated in several surveys worldwide in the last 10 years to verify the correlation between observed seismic energy anomalies at the surface and the presence of hydrocarbon reserves beneath. This is due to the premise that anomalies provide information about the geology and potential presence of hydrocarbon. However a technology gap manifested in nonoptimal detection of seismic signals of interest is observed. This is due to the fact that available sensors are not designed on the basis of passive seismic signal attributes and mainly in terms of amplitude and bandwidth. This is because of that fact that passive seismic acquisition requires greater instrumentation sensitivity, noise immunity, and bandwidth, with active seismic acquisition, where vibratory or impulsive sources were utilized to receive reflections through geophones. Therefore, in the case of passive seismic acquisition, it is necessary to select the best monitoring equipment for its success or failure. Hence, concerning sensors performance, this paper highlights the technological gap and motivates developing dedicated sensors for optimal solution at lower frequencies. Thus, the improved passive seismic recording helps in oil and gas industry to perform better fracture mapping and identify more appropriate stratigraphy at low frequencies.