bluuebunny/crossref_metadata_2025 huggingface dataset:
Differences in autonomic innervation to the vertebrobasilar arteries in spontaneously hypertensive and Wistar rats
Authors: Roloff Eva v. L. , Walas Dawid , Moraes Davi J. A. , Kasparov Sergey , Paton Julian F. R.
Published: May 2018

Key points

Essential hypertension is associated with hyperactivity of the sympathetic nervous system and hypoperfusion of the brainstem area controlling arterial pressure.

Sympathetic and parasympathetic innervation of vertebrobasilar arteries may regulate blood perfusion to the brainstem.

We examined the autonomic innervation of these arteries in pre‐hypertensive (PHSH) and hypertensive spontaneously hypertensive (SH) rats relative to age‐matched Wistar rats.

Our main findings were: (1) an unexpected decrease in noradrenergic sympathetic innervation in PHSH and SH compared to Wistar rats despite elevated sympathetic drive in PHSH rats; (2) a dramatic deficit in cholinergic and peptidergic parasympathetic innervation in PHSH and SH compared to Wistar rats; and (3) denervation of sympathetic fibres did not alter vertebrobasilar artery morphology or arterial pressure.

Our results support a compromised vasodilatory capacity in PHSH and SH rats compared to Wistar rats, which may explain their hypoperfused brainstem.

Neurogenic hypertension may result from brainstem hypoperfusion. We previously found remodelling (decreased lumen, increased wall thickness) in vertebrobasilar arteries of juvenile, pre‐hypertensive spontaneously hypertensive (PHSH) and adult spontaneously hypertensive (SH) rats compared to age‐matched normotensive rats. We tested the hypothesis that there would be a greater density of sympathetic to parasympathetic innervation of vertebrobasilar arteries in SH versus Wistar rats irrespective of the stage of development and that sympathetic denervation (ablation of the superior cervical ganglia bilaterally) would reverse the remodelling and lower blood pressure. Contrary to our hypothesis, immunohistochemistry revealed a decrease in the innervation density of noradrenergic sympathetic fibres in adult SH rats (P < 0.01) compared to Wistar rats. Unexpectedly, there was a 65% deficit in parasympathetic fibres, as assessed by both vesicular acetylcholine transporter (α‐VAChT) and vasoactive intestinal peptide (α‐VIP) immunofluorescence (P < 0.002) in PHSH rats compared to age‐matched Wistar rats. Although the neural activity of the internal cervical sympathetic branch, which innervates the vertebrobasilar arteries, was higher in PHSH relative to Wistar rats, its denervation had no effect on the vertebrobasilar artery morphology or persistent effect on arterial pressure in SH rats. Our neuroanatomic and functional data do not support a role for sympathetic nerves in remodelling of the vertebrobasilar artery wall in PHSH or SH rats. The remodelling of vertebrobasilar arteries and the elevated activity in the internal cervical sympathetic nerve coupled with their reduced parasympathetic innervation suggests a compromised vasodilatory capacity in PHSH and SH rats that could explain their brainstem hypoperfusion.
Biomechanical Robustness of a Contemporary Cementless Stem to Surgical Variation in Stem Size and Position
Authors: Al-Dirini Rami M. A. , O'Rourke Dermot , Huff Daniel , Martelli Saulo , Taylor Mark
Published: May 2018

Successful designs of total hip replacement (THR) need to be robust to surgical variation in sizing and positioning of the femoral stem. This study presents an automated method for comprehensive evaluation of the potential impact of surgical variability in sizing and positioning on the primary stability of a contemporary cementless femoral stem (Corail®, DePuy Synthes). A patient-specific finite element (FE) model of a femur was generated from computed tomography (CT) images from a female donor. An automated algorithm was developed to span the plausible surgical envelope of implant positions constrained by the inner cortical boundary. The analysis was performed on four stem sizes: oversized, ideal (nominal) sized, and undersized by up to two stem sizes. For each size, Latin hypercube sampling was used to generate models for 100 unique alignment scenarios. For each scenario, peak hip contact and muscle forces published for stair climbing were scaled to the donor's body weight and applied to the model. The risk of implant loosening was assessed by comparing the bone–implant micromotion/strains to thresholds (150 μm and 7000 με) above which fibrous tissue is expected to prevail and the periprosthetic bone to yield, respectively. The risk of long-term loosening due to adverse bone resorption was assessed using bone adaptation theory. The range of implant positions generated effectively spanned the available intracortical space. The Corail stem was found stable and robust to changes in size and position, with the majority of the bone–implant interface undergoing micromotion and interfacial strains that are well below 150 μm and 7000 με, respectively. Nevertheless, the range of implant positions generated caused an increase of up to 50% in peak micromotion and up to 25% in interfacial strains, particularly for retroverted stems placed in a medial position.
Determination of Elastic Modulus in Mouse Bones Using a Nondestructive Micro-Indentation Technique Using Reference Point Indentation
Authors: Thiagarajan Ganesh , Begonia Mark T. , Dallas Mark , Lara-Castillo Nuria , Scott JoAnna M. , Johnson Mark L.
Published: May 2018

The determination of the elastic modulus of bone is important in studying the response of bone to loading and is determined using a destructive three-point bending method. Reference point indentation (RPI), with one cycle of indentation, offers a nondestructive alternative to determine the elastic modulus. While the elastic modulus could be determined using a nondestructive procedure for ex vivo experiments, for in vivo testing, the three-point bending technique may not be practical and hence RPI is viewed as a potential alternative and explored in this study. Using the RPI measurements, total indentation distance (TID), creep indentation distance, indentation force, and the unloading slope, we have developed a numerical analysis procedure using the Oliver–Pharr (O/P) method to estimate the indentation elastic modulus. Two methods were used to determine the area function: (1) Oliver–Pharr (O/P—based on a numerical procedure) and (2) geometric (based on the calculation of the projected area of indentation). The indentation moduli of polymethyl methacrylate (PMMA) calculated by the O/P (3.49–3.68 GPa) and geometric (3.33–3.49 GPa) methods were similar to values in literature (3.5–4 GPa). In a study using femurs from C57Bl/6 mice of different ages and genders, the three-point bending modulus was lower than the indentation modulus. In femurs from 4 to 5 months old TOPGAL mice, we found that the indentation modulus from the geometric (5.61 ± 1.25 GPa) and O/P (5.53 ± 1.27 GPa) methods was higher than the three-point bending modulus (5.28 ± 0.34 GPa). In females, the indentation modulus from the geometric (7.45 ± 0.86 GPa) and O/P (7.46 ± 0.92 GPa) methods was also higher than the three-point bending modulus (7.33 ± 1.13 GPa). We can conclude from this study that the RPI determined values are relatively close to three-point bending values.
The Scaffold–Articular Cartilage Interface: A Combined In Vitro and In Silico Analysis Under Controlled Loading Conditions
Authors: Chen Tony , McCarthy Moira M. , Guo Hongqiang , Warren Russell , Maher Suzanne A.
Published: May 2018

The optimal method to integrate scaffolds with articular cartilage has not yet been identified, in part because of our lack of understanding about the mechanobiological conditions at the interface. Our objective was to quantify the effect of mechanical loading on integration between a scaffold and articular cartilage. We hypothesized that increased number of loading cycles would have a detrimental effect on interface integrity. The following models were developed: (i) an in vitro scaffold–cartilage explant system in which compressive sinusoidal loading cycles were applied for 14 days at 1 Hz, 5 days per week, for either 900, 1800, 3600, or 7200 cycles per day and (ii) an in silico inhomogeneous, biphasic finite element model (bFEM) of the scaffold–cartilage construct that was used to characterize interface micromotion, stress, and fluid flow under the prescribed loading conditions. In accordance with our hypothesis, mechanical loading significantly decreased scaffold–cartilage interface strength compared to unloaded controls regardless of the number of loading cycles. The decrease in interfacial strength can be attributed to abrupt changes in vertical displacement, fluid pressure, and compressive stresses along the interface, which reach steady-state after only 150 cycles of loading. The interfacial mechanical conditions are further complicated by the mismatch between the homogeneous properties of the scaffold and the depth-dependent properties of the articular cartilage. Finally, we suggest that mechanical conditions at the interface can be more readily modulated by increasing pre-incubation time before the load is applied, as opposed to varying the number of loading cycles.
Predicting Rotation in Fenestrated Endovascular Aneurysm Repair Using Finite Element Analysis
Authors: Sanford Ryan M. , Crawford Sean A. , Genis Helen , Doyle Matthew G. , Forbes Thomas L. , Amon Cristina H.
Published: May 2018

Fenestrated endovascular aneurysm repair (FEVAR) is a minimally invasive method of abdominal aortic aneurysm (AAA) repair utilized in patients with complex vessel anatomies. Stent grafts (SG) used in this process contain fenestrations within the device that need to be aligned with the visceral arteries upon successful SG deployment. Proper alignment is crucial to maintain blood flow to these arteries and avoid surgical complications. During fenestrated SG deployment, rotation of the SG can occur during the unsheathing process. This leads to misalignment of the vessels, and the fenestrations and is associated with poor clinical outcomes. The aim of this study was to develop a computational model of the FEVAR process to predict SG rotation. Six patient-specific cases are presented and compared with surgical case data. Realistic material properties, frictional effects, deployment methods, and boundary conditions are included in the model. A mean simulation error of 2 deg (range 1–4 deg) was observed. This model was then used to conduct a parameter study of frictional properties to see if rotation could be minimized. This study showed that increasing or decreasing the coefficients of friction (COF) between the sheath and the vessel walls would decrease the amount of rotation observed. Our model accurately predicts the amount of SG rotation observed during FEVAR and can be used as a preoperative planning tool within the surgical workflow.
Understanding Displacements of the Gel Liner for Below Knee Prosthetic Users
Authors: Lenz Amy L. , Johnson Katie A. , Tamara Reid Bush
Published: May 2018

Many people with amputation utilize a prosthetic device to maintain function and ambulation. During the use of the prosthetic device, their residual limbs can develop wounds called pressure ulcers. The formation of these wounds has been linked to deformation and loading conditions of the skin and deeper tissues. Our research objective was to develop a complete profile of displacements on the gel liner at the interface with the socket during walking in transtibial amputees. Displacements for seven regions along the limb were quantified in addition to six calculations of displacement and three rotations relative to the prosthetic socket. The largest displacements were observed in the distal region of the gel liner, near the pin locking mechanism on the gel liner. Displacements were uneven throughout the liner with distal regions showing higher displacements. This mechanics-based information, combined with clinical information, will allow us to understand the local skin and muscle displacements, and will provide insights regarding localized tissue breakdown. Knowledge of how the liner displaces within the prosthetic socket can also help prosthetists modify designs to reduce these displacements, and reduce the potential for shear on the skin and in deeper tissues.
Blind prediction of noncanonical RNA structure at atomic accuracy
Authors: Watkins Andrew M. , Geniesse Caleb , Kladwang Wipapat , Zakrevsky Paul , Jaeger Luc , Das Rhiju
Published: May 2018

We report a new algorithm and a battery of blind challenges for the prediction of complex RNA structures at atomic accuracy.
High-performance organic light-emitting diodes comprising ultrastable glass layers
Authors: Ràfols-Ribé Joan , Will Paul-Anton , Hänisch Christian , Gonzalez-Silveira Marta , Lenk Simone , Rodríguez-Viejo Javier , Reineke Sebastian
Published: May 2018

Organic light-emitting diodes with ultrastable glass emission layers show increased efficiency and device stability.
Recommendations To Address the Difficulties Encountered When Determining Linezolid Resistance from Whole-Genome Sequencing Data
Authors: Beukers Alicia G. , Hasman Henrik , Hegstad Kristin , van Hal Sebastiaan J.
Published: May 2018

Mutations associated with linezolid resistance within the V domain of 23S rRNA are annotated using an
Escherichia coli
numbering system. The 23S rRNA gene varies in length, nucleotide sequence, and copy number among bacterial species. Consequently, this numbering system is not intuitive and can lead to confusion when mutation sites are being located using whole-genome sequencing data. Using the mutation G2576T as an example, we demonstrate the difficulties associated with using the
E. coli
numbering system.
Disruption of
mpl
Activates β-Lactamase Production in Stenotrophomonas maltophilia and Pseudomonas aeruginosa Clinical Isolates
Authors: Calvopiña Karina , Avison Matthew B.
Published: May 2018

The hyperproduction of chromosomally encoded β-lactamases is a key method of acquired resistance to ceftazidime, aztreonam, and, when seen in backgrounds having reduced envelope permeability, carbapenems. Here, we show that the loss of Mpl, a UDP-muramic acid/peptide ligase, is a common and previously overlooked cause of chromosomally encoded β-lactamase hyperproduction in clinical isolates of
Stenotrophomonas maltophilia
and
Pseudomonas aeruginosa
, important pathogens notorious for their β-lactam-resistant phenotypes.
Experimental Evolution of Escherichia coli K-12 at High pH and with RpoS Induction
Authors: Hamdallah Issam , Torok Nadia , Bischof Katarina M. , Majdalani Nadim , Chadalavada Sriya , Mdluli Nonto , Creamer Kaitlin E. , Clark Michelle , Holdener Chase , Basting Preston J. , Gottesman Susan , Slonczewski Joan L.
Published: May 2018

Escherichia coli
in its native habitat encounters high-pH stress such as that of pancreatic secretions. Experimental evolution over 2,000 generations showed selection for mutations in regulatory factors, such as deletion of the phosphate regulator PhoB and mutations that alter the function of the global stress regulator RpoS. RpoS is induced at high pH via multiple mechanisms.
Filamentous Giant Beggiatoaceae from the Guaymas Basin Are Capable of both Denitrification and Dissimilatory Nitrate Reduction to Ammonium
Authors: Schutte Charles A. , Teske Andreas , MacGregor Barbara J. , Salman-Carvalho Verena , Lavik Gaute , Hach Philipp , de Beer Dirk
Published: May 2018

Whether large sulfur bacteria of the family
Beggiatoaceae
reduce NO
3
−
to N
2
via denitrification or to NH
4
+
via DNRA has been debated in the literature for more than 25 years. We resolve this debate by showing that certain members of the
Beggiatoaceae
use both metabolic pathways. This is important for the ecological role of these bacteria, as N
2
production removes bioavailable nitrogen from the ecosystem, whereas NH
4
+
production retains it. For this reason, the topic of environmental controls on the competition for NO
3
−
between N
2
-producing and NH
4
+
-producing bacteria is of great scientific interest. Recent experiments on the competition between these two types of microorganisms have demonstrated that the balance between electron donor and electron acceptor availability strongly influences the end product of NO
3
−
reduction. Our results suggest that this is also the case at the even more fundamental level of enzyme system regulation within a single organism.
The SMC5/6 Complex Interacts with the Papillomavirus E2 Protein and Influences Maintenance of Viral Episomal DNA
Authors: Bentley Peris , Tan Min Jie Alvin , McBride Alison A. , White Elizabeth A. , Howley Peter M.
Published: May 2018

The high-risk human papillomaviruses (HPVs) are the etiological cause of cervical cancer and the most common sexually transmitted infection. While the majority of infections may be asymptomatic or cause only benign lesions, persistent infection with the oncogenic high-risk HPV types may lead to serious diseases, such as cervical cancer, anogenital carcinoma, or head and neck oropharyngeal squamous cell carcinoma. The identification of virus-host protein interactions provides insights into the mechanisms of viral DNA persistence, viral genome replication, and cellular transformation. Elucidating the mechanism of early events in the virus replication cycle as well as of integration of viral DNA into host chromatin may present novel antiviral strategies and targets for counteracting persistent infection. The E2 protein is an important viral regulatory protein whose functions are mediated through interactions with host cell proteins. Here we explore the interaction of E2 with SMC5/6 and the functional consequences.
Fifteen-minute consultation: The angry child
Authors: Swanepoel Annie
Published: May 2018

Children who present with difficult behaviours due to underlying anger are commonly presented to paediatricians for help and advice. This paper gives a basic structure of how to approach the subject, by exploring whether the problems occur at home, school or both, and analysing the behaviour by focusing on antecedents, behaviour and consequences. It is important to find the underlying causes in order to know what to recommend, as this can vary from medication, anger management strategies, school-based interventions, parenting programmes or family therapy.
Incidence and trends of central line associated pneumothorax using radiograph report text search versus administrative database codes
Authors: Reeson Marc , Forster Alan , van Walraven Carl
Published: May 2018

Background

Central line associated pneumothorax (CLAP) could be a good quality of care indicator because they are objectively measured, clearly undesirable and possibly avoidable. We measured the incidence and trends of CLAP using radiograph report text search with manual review and compared them with measures using routinely collected health administrative data.

Methods

For each hospitalisation to a tertiary care teaching hospital between 2002 and 2015, we searched all chest radiography reports for a central line with a sensitive computer algorithm. Screen positive reports were manually reviewed to confirm central lines. The index and subsequent chest radiography reports were screened for pneumothorax followed by manual confirmation. Diagnostic and procedural codes were used to identify CLAP in administrative data.

Results

In 685 044 hospitalisations, 10 819 underwent central line insertion (1.6%) with CLAP occurring 181 times (1.7%). CLAP risk did not change over time. Codes for CLAP were inaccurate (sensitivity 13.8%, positive predictive value 6.6%). However, overall code-based CLAP risk (1.8%) was almost identical to actual values possibly because patient strata with inflated CLAP risk were balanced by more common strata having underestimated CLAP risk. Code-based methods inflated central line incidence 2.2 times and erroneously concluded that CLAP risk decreased significantly over time.

Conclusions

Using valid methods, CLAP incidence was similar to those in the literature but has not changed over time. Although administrative database codes for CLAP were very inaccurate, they generated CLAP risks very similar to actual values because of offsetting errors. In contrast to those from radiograph report text search with manual review, CLAP trends decreased significantly using administrative data. Hospital CLAP risk should not be measured using administrative data.
Contraceptive method use among women and its association with age, relationship status and duration: findings from the third British National Survey of Sexual Attitudes and Lifestyles (Natsal-3)
Authors: Firman Nicola , Palmer Melissa J , Timæus Ian M , Wellings Kaye
Published: May 2018

Background

One in six pregnancies in Britain are unplanned. An understanding of influences on contraceptive method choice is essential to provision compatible with users’ lifestyles. This study describes contraceptive method use by age, and relationship status and duration, among women in Britain.

Methods

Data from women participating in the third British National Survey of Sexual Attitudes and Lifestyles were used to describe contraceptive use grouped as: unreliable method or none; barrier methods; oral/injectable hormonal methods; and long-acting reversible contraception. A total of 4456 women at risk of pregnancy were used to examine associations between contraception use, age, relationship type and duration. Age-stratified odds ratios for contraceptive use by relationship type and duration were estimated using binary logistic regression.

Results

Some 26.0% of 16–49-year-olds used hormonal contraception as their usual method. Use of hormonal and barrier methods was highest in the youngest age group and decreased with age; the reverse was true for use of unreliable methods or none. Barrier method use was higher in short-term relationships among younger participants; this was not seen among older respondents. Duration was more strongly associated with usual contraceptive method than relationship type; this pattern was more marked among younger participants.

Conclusions

Asking about relationship status and duration may help providers support women’s contraceptive use by considering their priorities and preferences at different life stages. Interactions between relationship characteristics, age and contraception are complex, and bear closer scrutiny both in research and in policy and practice.
Prophylactic angiographic embolisation after endoscopic control of bleeding to high-risk peptic ulcers: a randomised controlled trial
Authors: Lau James Y W , Pittayanon Rapat , Wong Ka-Tak , Pinjaroen Nutcha , Chiu Philip Wai Yan , Rerknimitr Rungsun , Holster Ingrid Lisanne , Kuipers Ernst J , Wu Kai-Chun , Au Kim W L , Chan Francis K L , Sung Joseph J Y
Published: May 2018

Objectives

In the management of patients with bleeding peptic ulcers, recurrent bleeding is associated with high mortality. We investigated if added angiographic embolisation after endoscopic haemostasis to high-risk ulcers could reduce recurrent bleeding.

Design

After endoscopic haemostasis to their bleeding gastroduodenal ulcers, we randomised patients with at least one of these criteria (ulcers≥20 mm in size, spurting bleeding, hypotensive shock or haemoglobin<9 g/dL) to receive added angiographic embolisation or standard treatment. Our primary endpoint was recurrent bleeding within 30 days.

Results

Between January 2010 and July 2014, 241 patients were randomised (added angiographic embolisation n=118, standard treatment n=123); 22 of 118 patients (18.6%) randomised to angiography did not receive embolisation. In an intention-to-treat analysis, 12 (10.2%) in the embolisation and 14 (11.4%) in the standard treatment group reached the primary endpoint (HR 1.14, 95% CI 0.53 to 2.46; p=0.745). The rate of reinterventions (13 vs 17; p=0.510) and deaths (3 vs 5, p=0.519) were similar. In a per-protocol analysis, 6 of 96 (6.2%) rebled after embolisation compared with 14 of 123 (11.4%) in the standard treatment group (HR 1.89, 95% CI 0.73 to 4.92; p=0.192). None of 96 patients died after embolisation compared with 5 (4.1%) deaths in the standard treatment group (p=0.108). In a posthoc analysis, embolisation reduced recurrent bleeding only in patients with ulcers≥15 mm in size (2 (4.5%) vs 12 (23.1%); p=0.027).

Conclusions

After endoscopic haemostasis, added embolisation does not reduce recurrent bleeding.

Trial registration number

NCT01142180.
Assessment of the order Rhodymeniales (Rhodophyta) from British Columbia using an integrative taxonomic approach reveals overlooked and cryptic species diversity
Authors: Filloramo Gina V. , Saunders Gary W.
Published: May 2018

Molecular-assisted alpha taxonomy using COI-5P and rbcL-3P was employed to reassess species diversity for the Rhodymeniales (Rhodophyta) in British Columbia. A total of 563 collections from British Columbia were resolved as 16 genetic species groups, whereas 13 were previously reported. Collections attributed to Botryocladia pseudodichotoma from British Columbia were resolved as distinct from collections of that species from California (type locality) and were assigned to Botryocladia hawkesii sp. nov. DNA sequence data also resolved an additional species of Fryeella. Although two species of Gloiocladia were recognized, genetic analyses resolved three: G. fryeana, G. laciniata, and Gloiocladia vigneaultii sp. nov. Data also resolved Gloiocladia media comb. nov. from California. For the genus Rhodymenia, where two species were expected, DNA sequence data resolved four. Both R. californica and R. pacifica were confirmed in British Columbia, whereas some collections field-identified as R. californica were genetically distinct and assigned to the novel species, Rhodymenia bamfieldensis sp. nov. Some collections initially identified as R. pacifica were assigned to the resurrected species R. rhizoides. Anatomical development for the monospecific genus Minium was also reassessed owing to that taxon’s assignment to the Fryeellaceae. Our investigation clarified the number of rhodymenialean species in British Columbia and resolved taxonomic and distributional uncertainties associated with some of these taxa.
Nonsingular terminal sliding mode control of underwater remotely operated vehicles
Authors: Wang Yaoyao , Yan Fei , Tian Bo , Gu Linyi , Chen Bai
Published: May 2018

This study investigates the nonsingular terminal sliding mode control (NTSMC) method for the four-degree-of-freedom (4-DOF) trajectory tracking control problem of underwater remotely operated vehicles (ROVs) in the presence of parametric uncertainties and external disturbances. Two new control algorithms have been developed for ROVs. The first one, combining a nonsingular sliding surface with a fast terminal sliding mode (FTSM) type reaching law, is nonsingular and chattering-free. The second one, introducing adaptive methodology to compensate for lumped uncertainties, is an improved version of the first algorithm and can be called adaptive NTSMC (ANTSMC). The adaptive methodology effectively reduces the chattering problem. Meanwhile, it also provides better robustness and higher tracking precision compared with the first algorithm. A corresponding stability analysis is presented using Lyapunov stability theory, and some comparative numerical simulation results are presented to show the effectiveness of the proposed approaches.
Type synthesis of coordinated multi-robot system based on parallel thought
Authors: Xi Wanqiang , Chen Bai , Wang Yaoyao , Ju Feng
Published: May 2018

For the synthesis of the required type about the multi-robot coordination system in industrial transportation, this paper presents a novel method in which each robot in the coordinated task is viewed as a branched chain of an equivalent parallel robot (EPR), which is converted into a problem for type synthesis of parallel robots. A theoretic method is proposed to represent the kinematic features of the mechanism’s end-effector and its position and pose in the world coordinate system. The basic concept of a robotic characteristic (C) set is given, and the corresponding algorithm is analyzed. Based on the theory of C set, the concrete steps for type synthesis of EPR are presented by analyzing the characteristics of its branched chains, and many EPR groups with end kinematic features for the C sets of the operational tasks are obtained. Then three translational (3T) operational requirements that can be extended to other degrees of freedom (DOF) are adopted, and the DOF of homogeneous and heterogeneous EPR are analyzed using screw theory. Finally the validation of the method is demonstrated by Adams, which shows that the two groups are able to complete the task.
Effect of the charges of impurity on the absorption of quantum dot with magnetic field
Authors: Huang Jinsheng , Chen Gengxin
Published: May 2018

An investigation of the effect of charges of impurity on the optical properties of a hydrogenic impurity in a disk parabolic quantum dot under magnetic field has been performed by using the matrix diagonalization method. The ground state energy level becomes lower as the charges of impurity increase. The optical absorption coefficient strongly reduces with increasing charges of impurity and is strongly affected by the confinement strength, the magnetic field strength, and density of electron.
Ground-Constrained Motion Target Tracking for Monocular Sequence Images
Authors: Guo Ling
Published: May 2018

For the detection of a moving target position in video monitoring images, the existing locating tracking systems mainly adopt binocular or structured light stereoscopic technology, which has drawbacks such as system design complexity and slow detection speed. In light of these limitations, a tracking method for monocular sequence moving targets is presented, with the introduction of ground constraints into monocular visual monitoring; the principle and process of the method are introduced in detail in this paper. This method uses camera installation information and geometric imaging principles combined with nonlinear compensation to derive the calculation formula for the actual position of the ground moving target in monocular asymmetric nonlinear imaging. The footprint location of a walker is searched in the sequence imaging of a monitoring test platform that is built indoors. Because of the shadow of the walker in the image, the multi-threshold OTSU method based on test target background subtraction is used here to segment the images. The experimental results verify the effectiveness of the proposed method.
Face Recognition Based on Rearranged Modular Two-Dimensional Locality Preserving Projection
Authors: Jumahong Huxidan , Alimjan Gulnaz
Published: May 2018

This paper proposes a novel algorithm for feature extraction for face recognition, namely the rearranged modular two-dimensional locality preserving projection (Rm2DLPP). In the proposed algorithm, the original images are first divided into modular blocks, then the subblocks are rearranged to form two-dimensional matrices and finally the two-dimensional locality preserving projection algorithm is applied directly on the arranged matrices. The advantage of the Rm2DLPP algorithm is that it can utilize the local block features and global spatial structures of 2D face images simultaneously. The performance of the proposed method is evaluated and compared with other face recognition methods on the ORL, AR and FERET databases. The experimental results demonstrate the effectiveness and superiority of the proposed approach.
MARKOV SPECTRA OF SELF-SIMILAR NETWORKS BY SUBSTITUTION RULE
Authors: LI TINGTING , YE QIANQIAN , XI LIFENG
Published: May 2018

For a class of self-similar networks generated by substitution rules, we investigate them in terms of normalized Laplacian spectra. Accordingly, we obtain the recurrent structure of Markov spectra for these self-similar networks, and also estimate the smallest positive eigenvalue for Laplace operator.
FRACTAL MODEL OF GAS DIFFUSION THROUGH POROUS FIBROUS MATERIALS WITH ROUGH SURFACES
Authors: ZHENG QIAN , FAN JINTU , XU CHAO
Published: May 2018

Fractal model of gas diffusion through porous fibrous materials with rough surfaces is derived, in which the porous structure is simplified to be composed of a bundle of tortuous capillaries whose pore size distribution and surface roughness follow the fractal scaling laws. The analytical expression for gas relative diffusion coefficient is a function of the relative roughness, fiber radius and the other microstructural parameters (porosity, the fractal dimension for pore size distribution and tortuosity, the maximum and minimum pore diameter and the characteristic length). The proposed fractal model is validated by comparison with available experimental data and correlations. At the same time, the effect of microstructural parameters of porous fibrous materials on gas diffusion has been studied in detail. It is believed that the current model may be extended to porous materials other than fibrous materials.
FRACTAL DIMENSION DETERMINATION OF ROCK PORES BY MULTI-SCALE ANALYSIS OF IMAGES OBTAINED USING OM, SEM AND XCT
Authors: ALFONSO ISMELI , BELTRÁN ALBERTO , ABATAL MOHAMED , CASTRO IVÁN , FUENTES ALEJANDRA , VÁZQUEZ LEONOR , GARCÍA ARMANDO
Published: May 2018

The present work includes the analysis of the porosity at different scales using image characterization techniques. Porosities were determined and compared for reservoir rocks through the fractal dimensions obtained from two-dimensional (2D) image analysis. Studies were developed using Optical Microscopy (OM), Scanning Electron Microscopy (SEM) and X-ray Computed Tomography (XCT). In order to compare the images and analyze the similarities in the porosities, the box-counting method was used to extract the power-law distributions and to obtain the fractal dimensions. Results showed that fractal dimensions were similar for the three different techniques, which included different scale analysis, fact that demonstrates the fractal character of the porosity in the studied systems. The effectiveness of the use of 2D image analysis and the importance of the multiscale study of the porosity were also demonstrated.
FRACTAL-BASED ANALYSIS OF THE INFLUENCE OF CUTTING DEPTH ON COMPLEX STRUCTURE OF CUTTING FORCES IN ROUGH END MILLING
Authors: NAMAZI HAMIDREZA , FARID ALI AKHAVAN , SENG CHANG TECK
Published: May 2018

Analysis of the cutting forces during machining operations is an important issue. The rough end mill with the serrated profile is broadly used for reduction of cutting forces during milling operation. Since cutting force changes in random behavior during end milling, in this paper we employ fractal theory to analyze the complex structure of cutting force signal. For this purpose, we investigated the influence of variations of cutting depth on variations of fractal structure of cutting forces in wet and dry machining conditions. The results of our analysis showed the variations of fractal structure of cutting forces between different cutting depths, in wet and dry conditions. The employed methodology in this research is not limited to rough end milling and can potentially be applied to other types of machining operations, where the variations of cutting forces is an important issue.
Time-Variant Seismic Performance of Offshore RC Bridge Columns with Uncertainty
Authors: Li Hong-Nan , Cheng Hu , Wang Dong-Sheng
Published: May 2018

To establish a framework for evaluating the time-variant seismic performance of deteriorated reinforced concrete (RC) structures with uncertainty, offshore RC bridge columns exposed to marine environments are studied in this paper. The uncertainties from the material parameters, corrosion initiation time and earthquake ground motions are taken into account. Due to the different corrosion characteristics in various zones (i.e. the submerged zone, splash and tidal zone, and atmospheric zone) along the column height, corrosion-induced damages in each zone are considered separately, and the geometric mean of the yield displacements of the three zones is used to define the structural capacity (limit state). Meanwhile, the time-variant limit states are determined based on nonlinear static analyses, which reflect the current state of deteriorating RC columns. A total of four cases are studied using the Latin hypercube sampling (LHS) technique based on the probability distributions of the material parameters and corrosion initiation time, including the effects of statistical correlations among the material parameters. The results reveal that the seismic fragility is underestimated by a deterministic numerical model. The uncertainty in the corrosion initiation time influences the seismic fragility less significantly than that in the structural material parameters whether or not anti-corrosion measures are implemented. It is suggested that probabilistic methods should be used for seismic evaluation of deteriorating RC structures to consider the uncertainty involved.
Geographical Diversity of Alliance Portfolio and Firm Innovation: The Roles of Resource Characteristics and Governance Structures
Authors: Yang Qin
Published: May 2018

This paper explores how geographical diversity of an alliance portfolio benefits resource-based firm innovation. We propose that there are inverted U-shaped relationships between geographical diversity of an alliance portfolio and a firm’s radical and incremental innovation. In addition, resource characteristics and alliance governance structures are considered as important moderators between geographically diverse alliances and innovation. Relevant resources of alliance partners help focal firms to acquire valuable resources from different locations, thus improving organizational capabilities and achieving innovation. Governance structure choices concentrate on opportunism and transaction cost in coordinating resource sharing and recombination activities, which determine focal firms’ cost of knowledge management and then innovation outcome. Our research could advance the literature on alliance portfolio diversity by studying how firms use their alliance portfolio from diverse locations to recombine resources and then to enhance innovation, which remains less explored.
The Weeks Formation Konservat-Lagerstätte and the evolutionary transition of Cambrian marine life
Authors: Lerosey-Aubril Rudy , Gaines Robert R. , Hegna Thomas A. , Ortega-Hernández Javier , Van Roy Peter , Kier Carlo , Bonino Enrico
Published: May 2018

The Weeks Formation in Utah is the youngest (
c.
499 Ma) and least studied Cambrian Lagerstätte of the western USA. It preserves a diverse, exceptionally preserved fauna that inhabited a relatively deep water environment at the offshore margin of a carbonate platform, resembling the setting of the underlying Wheeler and Marjum formations. However, the Weeks fauna differs significantly in composition from the other remarkable biotas of the Cambrian Series 3 of Utah, suggesting a significant Guzhangian faunal restructuring. This bioevent is regarded as the onset of a transitional episode in the history of life, separating the two primary diversifications of the Early Paleozoic. The Weeks fossils have been strongly affected by late diagenetic processes, but some specimens still preserve exquisite anatomical details.

Supplementary material:
a supplementary text (material and methods), four supplementary tables (compositions of the lower and upper Weeks faunas, structure of the upper Weeks fauna, and results of the similarity analyses), and a supplementary data file (generic presence/absence matrix) are available at
https://doi.org/10.6084/m9.figshare.c.4109588
Sir Thomas Boverton Redwood (1846–1919): a watershed in the British oil industry
Authors: Sorkhabi Rasoul
Published: May 2018

Sir Thomas Boverton Redwood (1846–1919) stands as a giant in the history of petroleum science and technology. This paper pieces together scattered information about his life and work, and discusses his contributions, directly or indirectly, to petroleum exploration and production in various parts of the world, especially Burma (Myanmar), Persia, Mexico and the West Indies with which British colonial and commercial interests were related. Redwood established one of the first and most successful consulting firms for petroleum companies, and, in this way, trained generations of petroleum geologists and engineers. His masterpiece,
Petroleum: A Treatise
, which went through five editions from 1896 to 1926, summed up the knowledge of petroleum of its age, and still remains a valuable book for historical reference. Redwood's mediatory position between scientific, industrial and political circles in Britain enabled him to play a leading role in the development of petroleum technology, as well as Britain's oil operations around the world during the 1880s–1910s. He served as a technical advisor to many government committees and oil companies, and his total dedication to Britain's oil security during World War I and during the transformation of the Royal Navy's fleet from coal to oil fuel were the climax of his professional life.
Interdisciplinary Teaching Strategies for Designing and Building Effective Smartphone Applications
Authors: Cordova Carla Viviana Coleman , Banerjee Nilanjan
Published: May 2018

Working together, we've created an interdisciplinary project that teaches both designers and developers the life cycle and project management of mobile application development. Working with professional clients, visual arts and computer science students, we used teamwork to tackle real-world projects with deadlines, milestones, and budget constraints. Throughout the semester, students from the Advanced Interface Design and Mobile Programming classes collaborated to apply their design and programming experience to develop smartphone applications for clients. This paper presents the insights gathered from teaching this interdisciplinary course.
When Mixed Reality Meets Internet of Things
Authors: Park Taiwoo , Zhang Mi , Lee Youngki
Published: May 2018

From panoramic paintings and stereoscopic photos in the early 19th century, there has been a centurylong effort to realize mixed reality, interweaving real and virtual worlds that interact with each other. Recently, over the past few years, we have witnessed the first wave of "affordable" mixed reality platforms, such as Oculus Rift and Microsoft HoloLens hitting the market. In particular, 2017 was the showcase year of mixed reality technologies: The Academy awarded its first Oscar to virtual reality storytelling1; AAA caliber virtual reality games started to hit the market with impacts2. Furthermore, major mobile operating systems, including Android and iOS, began to support augmented reality at the platform level (e.g., Android ARCore, Apple ARKit). Looking down the road, a recent forecast by Orbis Research projects over $40 billion mixed reality market worldwide by 20203.
The Tick Programmable Low-Latency SDR System
Authors: Wu Haoyang , Wang Tao , Yuan Zengwen , Peng Chunyi , Li Zhiwei , Tan Zhaowei , Ding Boyan , Li Yuanjie , Liu Jun , Lu Songwu
Published: May 2018

Software-defined radio (SDR) allows users to build flexible and configurable wireless communication systems. A number of SDR platforms are already available for use [3, 4, 5]. However, given the latest technology push (e.g., 5G, wireless edge computing) and user demand pull (e.g., low-latency VR/AR, realtime control on drones), today's requirements on SDR are different. Ideally, SDR systems should offer sufficient programmability and ensure high performance for both physical (PHY) and medium access control (MAC) layers. Unfortunately, it is hard to achieve both in the existing SDR systems.
Backscatter as a Covert Channel in Mobile Devices
Authors: Yang Zhice , Huang Qianyi , Zhang Qian
Published: May 2018

Mobile devices, including laptops, smartphones, wearables, etc., have become essential tools in modern life. We rely on them for social activities, document processing, and health status monitoring. As these devices contain sensitive personal information, various security mechanisms, such as firewalls, traffic monitors, and information flow control systems [1], have been developed for mobile devices to prevent unauthorized data leakage.
Food and Language: Production, Consumption, and Circulation of Meaning and Value
Authors: Karrebæk Martha Sif , Riley Kathleen C. , Cavanaugh Jillian R.
Published: May 2018

We interrogate the many ways that language and food intersect. Food and its uses provide setting and structure for language, just as language and its uses constrain and inform food activities. We illuminate where and how food and language co-occur and how they are dynamically co-constitutive, foregrounding the potential for food-and-language scholarship to contribute to understandings of political economic processes and structures. We organize our review around the mutual production, consumption, and circulation of food and language. We show that the richness of scholarship about consumption (especially around the family meal) has not been matched by research concerning the production of food and language, whereas the co-constituting circulation of food and language contributes to new meanings and values for both. More research is needed to clarify the surging attention to food, which may be motivated by the complex global food system and the speed and ease of mediatization and circulation of food images and ideologies.
Genotype Imputation from Large Reference Panels
Authors: Das Sayantan , Abecasis Gonçalo R. , Browning Brian L.
Published: May 2018

Genotype imputation has become a standard tool in genome-wide association studies because it enables researchers to inexpensively approximate whole-genome sequence data from genome-wide single-nucleotide polymorphism array data. Genotype imputation increases statistical power, facilitates fine mapping of causal variants, and plays a key role in meta-analyses of genome-wide association studies. Only variants that were previously observed in a reference panel of sequenced individuals can be imputed. However, the rapid increase in the number of deeply sequenced individuals will soon make it possible to assemble enormous reference panels that greatly increase the number of imputable variants. In this review, we present an overview of genotype imputation and describe the computational techniques that make it possible to impute genotypes from reference panels with millions of individuals.
Cognition as a Window into Neuronal Population Space
Authors: Ruff Douglas A. , Ni Amy M. , Cohen Marlene R.
Published: May 2018

Understanding how cognitive processes affect the responses of sensory neurons may clarify the relationship between neuronal population activity and behavior. However, tools for analyzing neuronal activity have not kept up with technological advances in recording from large neuronal populations. Here, we describe prevalent hypotheses of how cognitive processes affect sensory neurons, driven largely by a model based on the activity of single neurons or pools of neurons as the units of computation. We then use simple simulations to expand this model to a new conceptual framework that focuses on subspaces of population activity as the relevant units of computation, uses comparisons between brain areas or to behavior to guide analyses of these subspaces, and suggests that population activity is optimized to decode the large variety of stimuli and tasks that animals encounter in natural behavior. This framework provides new ways of understanding the ever-growing quantity of recorded population activity data.
Nutritional Regulation of Intestinal Stem Cells
Authors: Alonso Salvador , Yilmaz Ömer H.
Published: May 2018

Dietary composition and calorie intake are major determinants of health and disease. Calorie restriction promotes metabolic changes that favor tissue regeneration and is arguably the most successful and best-conserved antiaging intervention. Obesity, in contrast, impairs tissue homeostasis and is a major risk factor for the development of diseases including cancer. Stem cells, the central mediators of tissue regeneration, integrate dietary and energy cues via nutrient-sensing pathways to maintain growth or respond to stress. We discuss emerging data on the effects of diet and nutrient-sensing pathways on intestinal stem cells, as well as their potential application in the development of regenerative and therapeutic interventions.