bluuebunny/crossref_metadata_2025 huggingface dataset:
Contributions of Material Properties and Structure to Increased Bone Fragility for a Given Bone Mass in the UCD-T2DM Rat Model of Type 2 Diabetes
Authors: Acevedo Claire , Sylvia Meghan , Schaible Eric , Graham James L , Stanhope Kimber L , Metz Lionel N , Gludovatz Bernd , Schwartz Ann V , Ritchie Robert O , Alliston Tamara N , Havel Peter J , Fields Aaron J
Published: January 2018

Adults with type 2 diabetes (T2D) have a higher fracture risk for a given bone quantity, but the mechanisms remain unclear. Using a rat model of polygenic obese T2D, we demonstrate that diabetes significantly reduces whole-bone strength for a given bone mass (μCT-derived BMC), and we quantify the roles of T2D-induced deficits in material properties versus bone structure; ie, geometry and microarchitecture. Lumbar vertebrae and ulnae were harvested from 6-month-old lean Sprague-Dawley rats, obese Sprague-Dawley rats, and diabetic obese UCD-T2DM rats (diabetic for 69 ± 7 days; blood glucose >200 mg/dL). Both obese rats and those with diabetes had reduced whole-bone strength for a given BMC. In obese rats, this was attributable to structural deficits, whereas in UCD-T2DM rats, this was attributable to structural deficits and to deficits in tissue material properties. For the vertebra, deficits in bone structure included thinner and more rod-like trabeculae; for the ulnae, these deficits included inefficient distribution of bone mass to resist bending. Deficits in ulnar material properties in UCD-T2DM rats were associated with increased non-enzymatic crosslinking and impaired collagen fibril deformation. Specifically, small-angle X-ray scattering revealed that diabetes reduced collagen fibril ultimate strain by 40%, and those changes coincided with significant reductions in the elastic, yield, and ultimate tensile properties of the bone tissue. Importantly, the biomechanical effects of these material property deficits were substantial. Prescribing diabetes-specific tissue yield strains in high-resolution finite element models reduced whole-bone strength by a similar amount (and in some cases a 3.4-fold greater amount) as the structural deficits. These findings provide insight into factors that increase bone fragility for a given bone mass in T2D; not only does diabetes associate with less biomechanically efficient bone structure, but diabetes also reduces tissue ductility by limiting collagen fibril deformation, and in doing so, reduces the maximum load capacity of the bone. © 2018 American Society for Bone and Mineral Research.
How many factors does the sense of community index assess?
Authors: Loomis Colleen , Wright Carrie
Published: January 2018

Studies of university students’ sense of community (SOC) use various scales, one of which is the widely used Sense of Community Index (SCI), conceptualized as a 4‐factor model: membership, influence, needs fulfillment, and shared emotional connection. Research has been unable to show a reliable 4‐factor solution. One possible explanation may be that negatively worded items contribute to lack of model fit, which would be consistent with the claim that SOC was conceptualized as a unipolar positive construct. Data were collected using a positively worded SCI (N = 794). Four models were tested with confirmatory factor analysis in structural equation modeling: 1‐factor, theorized four‐factor, revised 3‐factor, and revised 4‐factor. None of the models showed good fit, though the fit of the 1‐factor model was improved over the 4‐factor. More studies are needed to attempt replication with a positively worded SCI.
Binding of Cu+ and Cu2+ with peptides: Peptides = oxytocin, Arg8‐vasopressin, bradykinin, angiotensin‐I, substance‐P, somatostatin, and neurotensin
Authors: Jayasekharan Thankan , Gupta Shyam L. , Dhiman Vikas
Published: January 2018

The intrinsic binding ability of 7 natural peptides (oxytocin, arg8‐vasopressin, bradykinin, angiotensin‐I, substance‐P, somatostatin, and neurotensin) with copper in 2 different oxidation states (CuI/II) derived from different Cu+/2+ precursor sources have been investigated for their charge‐dependent binding characteristics. The peptide‐CuI/II complexes, [M − (n‐1)H + nCuI] and [M − (2n‐1)H + nCuII], are prepared/generated by the reaction of peptides with CuI solution/Cu‐target and CuSO4 solution and are analyzed by using matrix‐assisted laser desorption/ionization (MALDI) time‐of‐flight mass spectrometry. The MALDI mass spectra of both [M − (n‐1)H + nCuI] and [M − (2n‐1)H + nCuII] complexes show no mass shift due to the loss of ─H atoms in the main chain ─NH of these peptides by Cu+ and Cu2+ deprotonation. The measured m/z value indicates the reduction of CuI/II oxidation state into Cu0 during MALDI processes. The number and relative abundance of Cu+ bound to the peptides are greater compared with the Cu2+ bound peptides. Oxytocin, arg8‐vasopressin, bradykinin, substance‐P, and somatostatin show the binding of 5Cu+, and angiotensin‐I and neurotensin show the binding of 7Cu+ from both CuI and Cu targets, while bradykinin shows the binding of 2Cu2+, oxytocin, arg8‐vasopressin, angiotensin‐I, and substance‐P; somatostatin shows the binding of 3Cu2+; and neurotensin shows 4Cu2+ binding. The binding of more Cu+ with these small peptides signifies that the bonding characteristics of both Cu+ and Cu2+ are different. The amino acid residues responsible for the binding of both Cu+ and Cu2+ in these peptides have been identified based on the density functional theory computed binding energy values of Cu+ and the fragment transformation method predicted binding preference of Cu2+ for individual amino acids.
Microwave Vortex‐Beam Emitter Based on Spoof Surface Plasmon Polaritons
Authors: Yin Jia Yuan , Ren Jian , Zhang Lei , Li Haijiang , Cui Tie Jun
Published: January 2018

Since orbital angular momentum (OAM) being investigated intensively in the optical region, there have been growing interests in employing OAM to solve the problem in wireless communications as a new method. It is found that the independence between different OAM modes is crucial to wireless communications. Motivated by the tremendous potential of OAM in communication systems, a novel method to generate vortex beams by spoof surface plasmon polariton (SPP) is proposed. A looped double‐layer spoof SPP waveguide is applied to realize the transmission of electromagnetic waves. Beam emitting is accomplished through a series of circular patches, whose role is not only the radiation units but also resonators giving rise to the phase shifts required by the vortex beam. The proposed method is validated by both numerical simulation and experiment. The measured results show that spoof SPP are radiated by the circular patches and vortex beams carrying different OAM modes are observed at different frequencies. The proposed method possesses smaller size and is much easier to be integrated into systems and integrated circuits. The simple structure and design procedure make the proposed method promising in future wireless communication systems.
Design of Enzyme Micelles with Controllable Concavo‐Convex Micromorphologies for Highly Enhanced Stability and Catalytical Activity
Authors: Chen Tao , Xu Yuanhong , Yang Wenrong , Li Aihua , Wang Yao , Sun Jing , Liu Jingquan
Published: January 2018

Concavo‐convex micelles with controllable sizes and nanostructures are prepared via self‐assembling polymer–enzyme (e.g., shellac enzyme) conjugates with heterogeneous polymer chains, which exhibit higher enzyme stability (300%) and bioactivity (760%) comparing with the well‐defined ones. The applied amphiphilic and negatively charged copolymer, poly (methyl methacrylate)‐block‐poly (sodium p‐styrene sulfonate), is synthesized via reversible addition–fragmentation chain transfer polymerization to modify shellac enzyme and immobilize the enzyme bioactivity inducer by covalent conjugation and electrostatic attraction, respectively. The degradation test of catechol confirms the application potential of as‐prepared micelles as an efficient and economical decontaminant.
Gelatin Methacryloyl Hydrogels in the Absence of a Crosslinker as 3D Glioblastoma Multiforme (GBM)‐Mimetic Microenvironment
Authors: Erkoc Pelin , Seker Fidan , Bagci‐Onder Tugba , Kizilel Seda
Published: January 2018

3D platforms are important for monitoring tumor progression and screening drug candidates to eradicate tumors such as glioblastoma multiforme (GBM), a malignant type of human brain tumor. Here, a new strategy is reported that exploits visible‐light‐induced crosslinking of gelatin where the reaction is carried out in the absence of an additional crosslinker. Visible light‐induced crosslinking promotes the design of cancer microenvironment‐mimetic system without compromising the cell viability during the process and absence of crosslinker facilitates the synthesis of the unique construct. Suspension and spheroid‐based models of GBM are used to investigate cellular behavior, expression profiles of malignancy, and apoptosis‐related genes within this unique network. Furthermore, sensitivity to an anticancer drug, Digitoxigenin, treatment is investigated in detail. The data suggest that U373 cells, in sparse or spheroid form, have significantly decreased expressions of apoptosis‐activating genes, Bad, Puma, and Caspase‐3, and a high expression of prosurvival Bcl‐2 gene within GelMA hydrogels. Matrix‐metalloproteinase genes are also upregulated within GelMA, suggesting positive contribution of gels on extracellular remodeling of cancer cells. This unique photocurable gelatin holds great potential for clinical translation of cancer research through the analysis of 3D malignant cancer cell behavior, and hence for more efficient treatment methods for GBM.
Synthesis of Polypyrrole Inverse Opals through an Air–Water Interface Polymerization Method and Their Application in Dye‐Sensitized Solar Cells
Authors: Deng Liduo , Wang Likui , Li Yunxing , Shi Gang , Liu Yun , Yao Bolong
Published: January 2018

An air–water interface polymerization method is developed to fabricate polypyrrole inverse opals without overlayers. Colloidal crystals are transferred to the surface of a pyrrole solution, and addition of oxidizer leads to the polymerization of pyrrole on the surface of the colloidal crystals. Since the part of the colloidal crystal protruding from the solution surface are not coated during the polymerization, inverse opals with microbowl arrays at the top could be obtained after removal of the template. The synthesis of an inverse opal multilayer with this approach is also demonstrated. Additionally, polypyrrole inverse opals doped with various acids are used as counter electrodes for dye‐sensitized solar cells, the photoelectric conversion efficiencies of which could approach those achieved with a Pt electrode.
Ion Conduction and Viscoelastic Response of Epoxy‐Based Solid Polymer Electrolytes Containing Solvating Plastic Crystal Plasticizer
Authors: Jang Hye Kyeong , Jung Byung Mun , Choi U Hyeok , Lee Sang Bok
Published: January 2018

To develop a safe electrolyte for lithium‐ion batteries, solid polymer electrolytes (SPEs) are prepared using a commercially available cross‐linkable diglycidyl ether of bisphenol‐A (DGEBA) epoxy resin, a methyl tetrahydrophthalic anhydride (MeTHPA) curing agent, and a plastic crystal‐based electrolyte containing a mixture of succinonitrile (SN) and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) by a simple thermal curing process. For the uncured mixture of DGEBA/MeTHPA/SN/LiTFSI, oscillatory and steady shear measurements are conducted to investigate microstructure and processability; the storage modulus (G′) exceeds the loss modulus (G″) at all frequencies studied (solid‐like behavior) and the viscosity decreases with an increase in the shear rate (shear‐thinning behavior), demonstrating that there is a network structure, and the connected structure changes at high shear rates. Fourier transform infrared spectroscopy confirms the physical interactions between Li+of LiTFSI and anhydride group of MeTHPA, which are responsible for the network structure, and helps to rationalize the observed moduli and viscosity. For the cured epoxy‐based SPEs, their ionic conductivities follow the Arrhenius temperature dependence, and increasing SN/LiTFSI electrolyte content leads to higher conductivity and lower activation energy for conduction, resulting in ionic conductivity σDC≈ 2 × 10−4S cm−1with a shear modulus approachingG′ ≈ 1 MPa at room temperature.
The analysis of architectural languages for the needs of practitioners
Authors: Ozkaya Mert
Published: January 2018

Architectural languages (ALs) have attracted much attention as the modeling notations for specifying and reasoning about important design decisions. In this study, 124 different existing ALs have been analyzed for a set of requirements that are crucial for practitioners. These requirements are concerned with language definition, language features, and tool support. Some of the important findings obtained from the analysis are as follows: (1) performance is the top popular nonfunctional requirement supported by ALs; (2) no ALs offer both textual and visual notation sets, one of which could be used independently; (3) process algebras are the top preferred formal method by formal ALs; (4) the physical, deployment, and operational viewpoints are rarely supported by ALs; (5) the top preferred extension mechanism of the extensible ALs is XML for syntax extension; (6) Java is the top preferred programming language in generating software code; (7) the exhaustive model checking is the top preferred automated analysis method; (8) the logic‐based formal techniques are so popular in specifying system requirements; (9) among the analysis properties considered, consistency is the top supported property for the automated checking; and (10) most ALs do not provide any discussion platform (eg, forums). Hence, these findings can be used by the new AL developers in addressing the needs of practitioners and bridging the gaps in the field. Practitioners can also use the findings to find out about the existing ALs and compare them to choose the one(s) that suits their needs best.
An Ayurvedic Anti‐Diabetic Formulation Made fromCurcuma longaL. andEmblica officinalisL. Inhibits α‐Amylase, α‐Glucosidase, and Starch Digestion, In Vitro
Authors: Butala Megha A. , Kukkupuni Subrahmanya K. , Venkatasubramanian Padma , Vishnuprasad Chethala N.
Published: January 2018

Targeting digestive enzymes and controlling postprandial glycemia is an important approach in diabetes management. Dietary supplements that inhibit digestive enzymes are a promising strategy for managing hyperglycemia in diabetic and borderline patients, particularly those who consume high carbohydrate diets. The Indian traditional Ayurvedic system of medicine has lot to offer in this direction. The emerging trend of opting for complementary and alternative medicines for the management of life style diseases, like diabetes, is encouraging but has limited global acceptance due to inadequate information on their therapeutic efficacy and mode of action. The present work demonstratesNisha‐Amalaki(CE), an Ayurvedic anti‐diabetic formulation prepared fromCurcuma longaandEmblica officinalis, as a potential of digestive enzyme inhibitor using in vitro models. The benefit of using honey as an adjuvant for CE is also studied. A simulated in vitro digestion model adopted in the work facilitates the study of the formulation in total than its individual components. While CE inhibits α‐amylase (65%), α‐glucosidase (93%) and reduces starch digestion (≈60%), addition of honey (CEH) is found to improve α‐amylase inhibition to 107% with a higher inhibition of starch digestion. Bioassay guided fractionation of CE and CEH shows multiple fractions, a curcuminoid rich chloroform fraction and an aqueous fraction, possibly contributing to the observed pharmacological effects. In conclusion, the study reports the herbal formulation,Nisha‐Amalaki, as an inhibitor of starch digestion as well as a potential nutraceutical dietary supplement in the management of hyperglycemia.
Cornea-Derived Mesenchymal Stromal Cells Therapeutically Modulate Macrophage Immunophenotype and Angiogenic Function
Authors: Eslani Medi , Putra Ilham , Shen Xiang , Hamouie Judy , Tadepalli Asha , Anwar Khandaker N. , Kink John A. , Ghassemi Samaneh , Agnihotri Gaurav , Reshetylo Sofiya , Mashaghi Alireza , Dana Reza , Hematti Peiman , Djalilian Ali R.
Published: January 2018

Macrophages are crucial drivers of inflammatory corneal neovascularization and thus are potential targets for immunomodulatory therapies. We hypothesized that therapeutic use of cornea-derived mesenchymal stromal cells (cMSCs) may alter the function of macrophages. We found that cMSCs can modulate the phenotype and angiogenic function of macrophages. In vitro, cMSCs induce apoptosis of macrophages while preferentially promoting a distinct CD14hiCD16hiCD163hiCD206hi immunophenotype that has significantly reduced angiogenic effects based on in vitro angiogenesis assays. In vivo, application of cMSCs to murine corneas after injury leads to reduced macrophage infiltration and higher expression of CD206 in macrophages. Macrophages cocultured (“educated”) by cMSCs express significantly higher levels of anti-angiogenic and anti-inflammatory factors compared with control macrophages. In vivo, injured corneas treated with cMSC-educated macrophages demonstrate significantly less neovascularization compared with corneas treated with control macrophages. Knocking down the expression of pigment epithelial derived factor (PEDF) in cMSCs significantly abrogates its modulating effects on macrophages, as shown by the reduced rate of apoptosis, decreased expression of sFLT-1/PEDF, and increased expression of vascular endothelial growth factor-A in the cocultured macrophages. Similarly, cMSCs isolated from PEDF knockout mice are less effective compared with wild-type cMSCs at inhibiting macrophage infiltration when applied to wild-type corneas after injury. Overall, these results demonstrate that cMSCs therapeutically suppress the angiogenic capacity of macrophages and highlight the role of cMSC secreted PEDF in the modulation of macrophage phenotype and function.
Wind turbine sensor array for monitoring avian and bat collisions
Authors: Hu Congcong , Albertani Roberto , Suryan Robert M.
Published: January 2018

Assessment of avian and bat collisions with wind turbines is necessary to ensure that the benefits of renewable wind power generation are not outweighed by mortality of protected species. An onboard, integrated multisensor system capable of providing detection of turbine collision events, including taxonomic information, was developed. The conceptual design of a multisensor system including a vibration sensing node, an optics node, and an bioacoustic node with an event‐driven trigger architecture was field‐tested on utility‐scale wind turbines. A pixel density computational model was built to estimate the spatial coverage and target resolution to the optimized configuration for camera placement. Field test results of the vibration node showed that nearly half of the recorded impact events were successfully identified by visual inspection and running short‐time Fourier transform on recorded vibration signals. The remaining undetected impact events were masked under background noise due to low impact energy and high background noise of the operating turbine, which result in subsequent low signal‐to‐noise ratio. Our results demonstrate the feasibility of triggering the system through single impact event sensed by vibration sensors.
A survey of incremental high‐utility itemset mining
Authors: Gan Wensheng , Lin Jerry Chun‐Wei , Fournier‐Viger Philippe , Chao Han‐Chieh , Hong Tzung‐Pei , Fujita Hamido
Published: January 2018

Traditional association rule mining has been widely studied. But it is unsuitable for real‐world applications where factors such as unit profits of items and purchase quantities must be considered. High‐utility itemset mining (HUIM) is designed to find highly profitable patterns by considering both the purchase quantities and unit profits of items. However, most HUIM algorithms are designed to be applied to static databases. But in real‐world applications such as market basket analysis and business decision‐making, databases are often dynamically updated by inserting new data such as customer transactions. Several researchers have proposed algorithms to discover high‐utility itemsets (HUIs) in dynamically updated databases. Unlike batch algorithms, which always process a database from scratch, incremental high‐utility itemset mining (iHUIM) algorithms incrementally update and output HUIs, thus reducing the cost of discovering HUIs. This paper provides an up‐to‐date survey of the state‐of‐the‐art iHUIM algorithms, including Apriori‐based, tree‐based, and utility‐list‐based approaches. To the best of our knowledge, this is the first survey on the mining task of incremental high‐utility itemset mining. The paper also identifies several important issues and research challenges for iHUIM. WIREs Data Mining Knowl Discov 2018, 8:e1242. doi: 10.1002/widm.1242

This article is categorized under:

Algorithmic Development > Association Rules

Application Areas > Data Mining Software Tools

Fundamental Concepts of Data and Knowledge > Knowledge Representation
Have You Ever Googled a Patient or Been Friended by a Patient? Social Media Intersects the Practice of Genetic Counseling
Authors: Omaggio NinaMarie F. , Baker Maria J. , Conway Laura J.
Published: January 2018

Patients and healthcare providers are becoming increasingly connected via social media, bringing new opportunities and challenges. Direct connection can occur between patients and providers using online tools such as Facebook and LinkedIn. In addition, providers can gather information about patients using a search engine such as Google, referred to as patient‐targeted Googling (PTG). An online 54‐item survey was used to gain information on (1) how and to what extent genetic counseling students and genetic counselors connect directly with patients via social media sites, and (2) gather information on providers using PTG. Four hundred genetic counseling students and genetic counselors participated in the survey. The majority of respondents (88.9%; n = 344/387) find it is never or rarely acceptable to interact with current patients via social media sites; however, 27.7% (n = 110/397) have visited a patient's social media site. Gathering information for patient care was the most commonly reported reason (76.8%; n = 43/56). Thirty‐three percent (n = 130/394) have considered searching online or actually searched online for information about a patient. Curiosity was the most common reason (92.7%; n = 114/123); although, respondents also used PTG to obtain contact information and to prepare for patient sessions. Our study supports the need for development and dissemination of professional guidelines to serve as a valuable resource for practicing genetic counselors and genetic counseling training programs.
Petrogenesis of the Late Cenozoic collision volcanism in the central part of the Lesser Caucasus (Azerbaijan)
Authors: Imamverdiyev N.A. , Gasangulieva M.Ya. , Babaeva G.J. , Abdullaeva Sh.F. , Veliev A.A.
Published: January 2018

The Late Cenozoic volcanics of the Lesser Caucasus have similar trace-element and REE patterns with negative anomalies of Nb, Ta, Hf, and Zr. They are highly enriched in Rb, Ba, Th, and La and depleted in Ti, Yb, and Y with respect to N-MORB, which indicates their formation from the subduction-metasomatized lithospheric mantle. Partial melting of the subcontinental mantle lithosphere and crustal assimilation and fractional crystallization controlled the magma evolution in the collisional magmatic belts.
The Upper Ordovician of northeastern Gorny Altai: Stratigraphy and deposition environments
Authors: Sennikov N.V. , Obut O.T. , Tolmacheva T.Yu. , Lykova E.V. , Khabibulina R.A.
Published: January 2018

Comprehensive lithofacies and biofacies analysis provided constraints on the origin of Upper Ordovician clastic and carbonate deposits in northeastern Gorny Altai, which form large low-elevated flat carbonate banks located relatively close to the shore. The sediments were deposited during the Sandbian and early–middle Katian stages, according to new conodont data. Upper Ordovician sections in northeastern Gorny Altai store record of two global regressions: the early Sandbian (Vollen Lowstand) and early Katian (Frognerkilen Lowstand) events.
How gender- and violence-related norms affect self-esteem among adolescent refugee girls living in Ethiopia
Authors: Stark L. , Asghar K. , Seff I. , Cislaghi B. , Yu G. , Tesfay Gessesse T. , Eoomkham J. , Assazenew Baysa A. , Falb K.
Published: January 2018

Background.

Evidence suggests adolescent self-esteem is influenced by beliefs of how individuals in their reference group perceive them. However, few studies examine how gender- and violence-related social norms affect self-esteem among refugee populations. This paper explores relationships between gender inequitable and victim-blaming social norms, personal attitudes, and self-esteem among adolescent girls participating in a life skills program in three Ethiopian refugee camps.

Methods.

Ordinary least squares multivariable regression analysis was used to assess the associations between attitudes and social norms, and self-esteem. Key independent variables of interest included a scale measuring personal attitudes toward gender inequitable norms, a measure of perceived injunctive norms capturing how a girl believed her family and community would react if she was raped, and a peer-group measure of collective descriptive norms surrounding gender inequity. The key outcome variable, self-esteem, was measured using the Rosenberg self-esteem scale.

Results.

Girl's personal attitudes toward gender inequitable norms were not significantly predictive of self-esteem at endline, when adjusting for other covariates. Collective peer norms surrounding the same gender inequitable statements were significantly predictive of self-esteem at endline (ß = −0.130;p  =  0.024). Additionally, perceived injunctive norms surrounding family and community-based sanctions for victims of forced sex were associated with a decline in self-esteem at endline (ß = −0.103;p  =  0.014). Significant findings for collective descriptive norms and injunctive norms remained when controlling for all three constructs simultaneously.

Conclusions.

Findings suggest shifting collective norms around gender inequity, particularly at the community and peer levels, may sustainably support the safety and well-being of adolescent girls in refugee settings.
On the skin friction due to turbulence in ducts of various shapes
Authors: Spalart P. R. , Garbaruk A. , Stabnikov A.
Published: January 2018

We consider fully developed turbulence in straight ducts of non-circular cross-sectional shape, for instance a square. A global friction velocity $\overline{u}_{\unicode[STIX]{x1D70F}}$ is defined from the streamwise pressure gradient $|\text{d}p/\text{d}x|$ and a single characteristic length $h$, half the hydraulic diameter (shapes with disparate length scales, due to high aspect ratio, are excluded). We reason that as the Reynolds number $Re$ reaches high values, outside the viscous region the streamwise velocity differences and the secondary motion scale with $\overline{u}_{\unicode[STIX]{x1D70F}}$ and the Reynolds stresses with $\overline{u}_{\unicode[STIX]{x1D70F}}^{2}$. This extends the classical defect-law argument, associated with Townsend and many others, and is successful in channel and pipe flows. We then posit matched asymptotic expansions with overlap of the law of the wall and the behaviour we assumed in the core region. The wall may be smooth, or have a Nikuradse roughness $k_{S}$ (such that it is fully rough, with $k_{S}^{+}\gg 1$). The consequences include the familiar logarithmic behaviour of the velocity profile, but also the surprising prediction that the skin friction tends to uniformity all around the duct, except near possible corners, asymptotically as $Re\rightarrow \infty$ or $k_{S}/h\rightarrow 0$. This is confirmed by numerical solutions for a square and two ellipses, using a conventional turbulence model, albeit the trend with Reynolds number is slow. The magnitude of the secondary motion also scales as expected, and the skin-friction coefficient follows the logarithm of the appropriate Reynolds number. This is a validation of the mathematical reasoning, but is by no means independent physical evidence, because the turbulence models embody the same assumptions as the theory. The uniformity of the skin friction appears to be a new and falsifiable deduction from turbulence theory, and a candidate for high-Reynolds-number experiments.
Relocation of clustered earthquakes in the Groningen gas field
Authors: Jagt Lisanne , Ruigrok Elmer , Paulssen Hanneke
Published: January 2018

Previous locations of earthquakes induced by depletion of the Groningen gas field were not accurate enough to infer which faults in the reservoir are reactivated. A multiplet analysis is performed to identify clusters of earthquakes that have similar waveforms, representing repeating rupture on the same or nearby faults. The multiplet analysis is based on the cross-correlation of seismograms to assess the degree of similarity. Using data of a single station, six earthquake clusters within the limits of the Groningen field were identified for the period 2010 to mid-2014. Four of these clusters were suitable for a relocation method that is based on the difference in travel time between the P- and the S-wave. Events within a cluster can be relocated relative to a master event with improved accuracy by cross-correlating first arrivals. By choosing master events located with a new dense seismic network, the relocated events likely not only have better relative, but also improved absolute locations. For a few clusters with sufficient signal-to-noise detections, we show that the relocation method is successful in assigning clusters to specific faults at the reservoir level. Overall, about 90% of the events did not show clustering, despite choosing low correlation thresholds of 0.5 and 0.6. This suggests that different faults and/or fault segments with likely varying source mechanisms are active in reservoir sub-regions of a few square kilometres.
History match of the Groningen field dynamic reservoir model to subsidence data and conventional subsurface data
Authors: van Oeveren Hendrik , Valvatne Per , Geurtsen Leendert , van Elk Jan
Published: January 2018

This paper presents the method applied to history-match the Groningen field dynamic model to conventional data (pressure data and water influx data) and to subsidence data, which is a novelty. Modelled subsidence is matched to subsidence data based on a simplified geomechanical model, which was built into the dynamic simulator.

A two-tier method was used to first achieve a match on a field-wide scale using field-average history-match quantifiers, which was then further improved at a regional/well level using regional history-match quantifiers. The history match was assisted by a space-filling experimental design. The resulting model has a field-average match to pressure data of ±2.17bar with a measurement uncertainty of ±0.4bar, to water influx data of ±2m with a measurement uncertainty of ±0.5m, and to subsidence data of ±4cm with a measurement uncertainty of ±1cm.

The output from this model is used as input for compaction, subsidence and production forecasts feeding into the hazard and risk assessment completed by NAM for the Groningen Winningsplan 2016.
Field-wide reservoir compressibility estimation through inversion of subsidence data above the Groningen gas field
Authors: van Eijs Rob M.H.E. , van der Wal Onno
Published: January 2018

Not long after discovery of the Groningen field, gas-production-induced compaction and consequent land subsidence was recognised to be a potential threat to groundwater management in the province of Groningen, in addition to the fact that parts of the province lie below sea level. More recently, NAM's seismological model also pointed to a correlation between reservoir compaction and the observed induced seismicity above the field. In addition to the already existing requirement for accurate subsidence predictions, this demanded a more accurate description of the expected spatial and temporal development of compaction.

Since the start of production in 1963, multiple levelling campaigns have gathered a unique set of deformation measurements used to calibrate geomechanical models. In this paper we present a methodology to model compaction and subsidence, combining results from rock mechanics experiments and surface deformation measurements. Besides the optical spirit-levelling data, InSAR data are also used for inversion to compaction and calibration of compaction models. Residual analysis, i.e. analysis of the difference between measurement and model output, provides confidence in the model results used for subsidence forecasting and as input to seismological models.
Hazard and risk assessments for induced seismicity in Groningen
Authors: van Elk Jan , Doornhof Dirk , Bommer Julian J. , Bourne Stephen J. , Oates Steve J. , Pinho Rui , Crowley Helen
Published: January 2018

Earthquakes associated with gas production have been recorded in the northern part of the Netherlands since 1986. The Huizinge earthquake of 16 August 2012, the strongest so far with a magnitude ofML= 3.6, prompted reassessment of the seismicity induced by production from the Groningen gas field. An international research programme was initiated, with the participation of many Dutch and international universities, knowledge institutes and recognised experts.

The prime aim of the programme was to assess the hazard and risk resulting from the induced seismicity. Classic probabilistic seismic hazard and risk assessment (PSHA) was implemented using a Monte Carlo method. The scope of the research programme extended from the cause (production of gas from the underground reservoir) to the effects (risk to people and damage to buildings). Data acquisition through field measurements and laboratory experiments was a substantial element of the research programme. The existing geophone and accelerometer monitoring network was extended, a new network of accelerometers in building foundations was installed, geophones were placed at reservoir level in deep wells, GPS stations were installed and a gravity survey was conducted.

Results of the probabilistic seismic hazard and risk assessment have been published in production plans submitted to the Minister of Economic Affairs, Winningsplan Groningen 2013 and 2016 and several intermediate updates. The studies and data acquisition further constrained the uncertainties and resulted in a reduction of the initially assessed hazard and risk.
Geomechanical models for induced seismicity in the Netherlands: inferences from simplified analytical, finite element and rupture model approaches
Authors: Van Wees Jan-Diederik , Fokker Peter A. , Van Thienen-Visser Karin , Wassing Brecht B.T. , Osinga Sander , Orlic Bogdan , Ghouri Saad A. , Buijze Loes , Pluymaekers Maarten
Published: January 2018

In the Netherlands, over 190 gas fields of varying size have been exploited, and 15% of these have shown seismicity. The prime cause for seismicity due to gas depletion is stress changes caused by pressure depletion and by differential compaction. The observed onset of induced seismicity due to gas depletion in the Netherlands occurs after a considerable pressure drop in the gas fields. Geomechanical studies show that both the delay in the onset of induced seismicity and the nonlinear increase in seismic moment observed for the induced seismicity in the Groningen field can be explained by a model of pressure depletion, if the faults causing the induced seismicity are not critically stressed at the onset of depletion. Our model shows concave patterns of log moment with time for individual faults. This suggests that the growth of future seismicity could well be more limited than would be inferred from extrapolation of the observed trend between production or compaction and seismicity. The geomechanical models predict that seismic moment increase should slow down significantly immediately after a production decrease, independently of the decay rate of the compaction model. These findings are in agreement with the observed reduced seismicity rates in the central area of the Groningen field immediately after production decrease on 17 January 2014. The geomechanical model findings therefore support scope for mitigating induced seismicity by adjusting rates of production and associated pressure change. These simplified models cannot serve as comprehensive models for predicting induced seismicity in any particular field. To this end, a more detailed field-specific study, taking into account the full complexity of reservoir geometry, depletion history and mechanical properties, is required.
Calibrated density profiles of Caribbean mangrove peat sequences from computed tomography for assessment of peat preservation, compaction, and impacts on sea-level reconstructions
Authors: Toscano Marguerite A. , Gonzalez Juan L. , Whelan Kevin R.T.
Published: January 2018

Oceanic mangroves accumulate peat with sea-level rise without terrestrial sediment inputs, but fossil peat’s elevation as a tide-range limited sea-level indicator is assumed to be affected by compaction. Despite assumption of decomposition, compression, and dewatering, pure Rhizophora mangle peat appears coarse, water-saturated, and loose even at depth. Calibrated peat densities from computed tomography (CT) and petrologic analysis allow quantitative assessment of compaction in continuous peats from Florida (6 m thick), Belize (12 m thick), and Panama (3.5 m thick). Pure peat exhibits voids at all depths and >80% water contents. CT density does not increase with depth; bulk densities are low, minimally variable, and trend-free. Higher CT-density intervals coincide with compositional changes (sediment, coral). CT of peat buried under sediment shows a shift to higher densities. CT of air-dried continuous peat shows uncompressed fine and coarse roots and voids, with negative densities indicative of air in place of interstitial water. Peat’s high water content and hydraulic conductivity prevent dewatering and compaction, hypothetically maintaining original sea-level indicative elevations at intermediate depths. Non-compacted, sediment-free, offshore peats can provide a continuous proxy for reconstructing the record of sea-level rise at any site, if depositional, disturbance, and geochemical and biotic processes affecting 14C ages are also assessed.
Derivative-free Nonlinear Version of Extended Recursive Three-step Filter for State and Parameter Estimation during Mars Entry
Authors: Xiao Mengli , Zhang Yongbo , Fu Huimin , Wang Zhihua
Published: January 2018

Parameter uncertainties which may lead to divergence of traditional Kalman filters during Mars entry are investigated in this paper. To achieve high precision navigation, a Derivative-free Nonlinear version of an Extended Recursive Three-Step Filter (DNERTSF) is introduced, which suits nonlinear systems with arbitrary parameter uncertainties. A DNERTSF can estimate the state and the parameters simultaneously, and Jacobian and Hessian calculations are not necessary for this filter. Considering the uncertainties in atmosphere density, ballistic coefficient and lift-to-drag ratio, a numerical simulation of Mars entry navigation is carried out. Compared with the standard Unscented Kalman Filter (UKF), DNERTSF can effectively reduce the adverse effects of parameter uncertainties and achieve a high navigation accuracy performance, keeping position and velocity estimation errors at a very low level. In all, the DNERTSF in this paper shows good advantages for Mars entry navigation, providing a possible application for a future Mars pinpoint landing.
Online market research panel members as controls in case–control studies to investigate gastrointestinal disease outbreaks: early experiences and lessons learnt from the UK
Authors: Mook P. , McCormick J. , Kanagarajah S. , Adak G. K. , Cleary P. , Elson R. , Gobin M. , Hawker J. , Inns T. , Sinclair C. , Trienekens S. C. M , Vivancos R. , McCarthy N.D.
Published: January 2018

Established methods of recruiting population controls for case–control studies to investigate gastrointestinal disease outbreaks can be time consuming, resulting in delays in identifying the source or vehicle of infection. After an initial evaluation of using online market research panel members as controls in a case–control study to investigate aSalmonellaoutbreak in 2013, this method was applied in four further studies in the UK between 2014 and 2016. We used data from all five studies and interviews with members of each outbreak control team and market research panel provider to review operational issues, evaluate risk of bias in this approach and consider methods to reduce confounding and bias. The investigators of each outbreak reported likely time and cost savings from using market research controls. There were systematic differences between case and control groups in some studies but no evidence that conclusions on the likely source or vehicle of infection were incorrect. Potential selection biases introduced by using this sampling frame and the low response rate are unclear. Methods that might reduce confounding and some bias should be balanced with concerns for overmatching. Further evaluation of this approach using comparisons with traditional methods and population-based exposure survey data is recommended.
Parallel droplet microfluidics for high throughput cell encapsulation and synthetic microgel generation
Authors: Headen Devon M. , García José R. , García Andrés J.
Published: January 2018

Cells can be microencapsulated in synthetic hydrogel microspheres (microgels) using droplet microfluidics, but microfluidic devices with a single droplet generating geometry have limited throughput, especially as microgel diameter decreases. Here we demonstrate microencapsulation of human mesenchymal stem cells (hMSCs) in small (<100 μm diameter) microgels utilizing parallel droplet generators on a two-layer elastomer device, which has 600% increased throughput vs. single-nozzle devices. Distribution of microgel diameters were compared between products of parallel vs. single-nozzle configurations for two square nozzle widths, 35 and 100 μm. Microgels produced on parallel nozzles were equivalent to those produced on single nozzles, with substantially the same polydispersity. Microencapsulation of hMSCs was compared for parallel nozzle devices of each width. Thirty five micrometer wide nozzle devices could be operated at twice the cell concentration of 100 μm wide nozzle devices but produced more empty microgels than predicted by a Poisson distribution. Hundred micrometer wide nozzle devices produced microgels as predicted by a Poisson distribution. Polydispersity of microgels did not increase with the addition of cells for either nozzle width. hMSCs encapsulated on 35 μm wide nozzle devices had reduced viability (~70%) and a corresponding decrease in vascular endothelial growth factor (VEGF) secretion compared to hMSCs cultured on tissue culture (TC) plastic. Encapsulating hMSCs using 100 μm wide nozzle devices mitigated loss of viability and function, as measured by VEGF secretion.
Transcriptomic alterations during ageing reflect the shift from cancer to degenerative diseases in the elderly
Authors: Aramillo Irizar Peer , Schäuble Sascha , Esser Daniela , Groth Marco , Frahm Christiane , Priebe Steffen , Baumgart Mario , Hartmann Nils , Marthandan Shiva , Menzel Uwe , Müller Jule , Schmidt Silvio , Ast Volker , Caliebe Amke , König Rainer , Krawczak Michael , Ristow Michael , Schuster Stefan , Cellerino Alessandro , Diekmann Stephan , Englert Christoph , Hemmerich Peter , Sühnel Jürgen , Guthke Reinhard , Witte Otto W. , Platzer Matthias , Ruppin Eytan , Kaleta Christoph
Published: January 2018

Disease epidemiology during ageing shows a transition from cancer to degenerative chronic disorders as dominant contributors to mortality in the old. Nevertheless, it has remained unclear to what extent molecular signatures of ageing reflect this phenomenon. Here we report on the identification of a conserved transcriptomic signature of ageing based on gene expression data from four vertebrate species across four tissues. We find that ageing-associated transcriptomic changes follow trajectories similar to the transcriptional alterations observed in degenerative ageing diseases but are in opposite direction to the transcriptomic alterations observed in cancer. We confirm the existence of a similar antagonism on the genomic level, where a majority of shared risk alleles which increase the risk of cancer decrease the risk of chronic degenerative disorders and vice versa. These results reveal a fundamental trade-off between cancer and degenerative ageing diseases that sheds light on the pronounced shift in their epidemiology during ageing.
Application of cardiovascular virtual endoscopy: a pilot study on roaming path planning for diagnosis of congenital heart diseases in children
Authors: Yao Li-Ping , Mei Ju , Ding Fang-Bao , Zhang Li , Li Hui-Ming , Ding Ming , Yang Xin , Li Xiao-Ming , Sun Kun
Published: January 2018

To investigate roaming paths planning for diagnosis of congenital heart diseases (CHD) using a cardiovascular virtual endoscopy (VE) system. Forty children were enrolled. VE system was applied to support in establishing a diagnosis. Performance in diagnosing CHDs by CT, VE using automatically planned roaming paths (VE-auto, objects were treated as left heart system and right heart system), VE using manually planned paths (VE-manual), and VE using automatically planned path for left heart system and manually planned path for right heart system (VE-combined) were studied and compared. Comparable accuracy of 93%, 93%, 95% and 95% was found by CT, VE-auto, VE-manual and VE-combined. However, in diagnosing tetralogy of Fallot, significantly higher performance was found by VEs, compared with CT. For VE-auto, poor performance with an accuracy of 85% and sensitivity of 22% was revealed in diagnosing muscular ventricular septal defect, compared with VE-manual and VE-combined. Compared with VE-manual, VE-combined illustrated comparable diagnostic accuracy on all CHDs; however, significantly smaller diagnostic time was utilized (P < 0.05).Cardiovascular VE system demonstrated considerable clinical value in the diagnosis of CHDs. Left and right heart system should not be modeled as two cavity objects simultaneously. When one of two systems is treated as one object, the other system should be treated as three separate objects when using VE to diagnose CHDs.