bluuebunny/crossref_metadata_2025 huggingface dataset:
Pattern analysis accounts for heterogeneity observed in MRI studies of tumor angiogenesis
Authors: Dominietto Marco , Lehmann Steffi , Keist Ruth , Rudin Markus
Published: December 2012

MRI is a method of choice for assessing anatomical structures or angiogenesis‐related parameters noninvasively during tumor progression. Typically, tumor tissue displays a high degree of heterogeneity that can be evaluated using pattern analysis (PA), which comprises shape and texture analysis. This work aims at implementing PA methods to study angiogenesis in a murine tumor model and testing its sensitivity with regard to detecting changes elicited by administration of a drug. Twelve balb/c‐nude mice were injected subcutaneously with 106 C51 cells (colon carcinoma). A first group (N = 6) of animals was treated with dimethyloxalylglycine, a drug known to stabilize hypoxia‐inducible‐factor‐α, which among other functions, is involved in angiogenesis. The second group (N = 6) was treated with saline. MRI experiments assessing tumor blood volume and permeability‐maps (Ktrans) were performed immediately before and 6 days after drug treatment. Data have been analyzed using standard histogram analysis and PA. Standard histogram analysis did not reveal any difference between the two groups, neither before nor after the treatment. In contrast, PA revealed significant differences between drug and placebo treated mice in the texture of the TBV and Ktrans maps after drug treatment, but not with regard to tumors shapes. The results indicated that in view of the heterogeneity of tumor tissue, standard histogram analysis appears insensitive in picking‐up differences in response to treatment, while PA appears to be particularly sensitive to changes in texture. Magn Reson Med 70:1481–1490, 2013. © 2012 Wiley Periodicals, Inc.
Spin echo measurements of the extravasation and tumor cell uptake of hyperpolarized [1‐13C]lactate and [1‐13C]pyruvate
Authors: Kettunen Mikko I. , Kennedy Brett W. C. , Hu De‐en , Brindle Kevin M.
Published: December 2012

Purpose

To assess the blood‐tissue distribution of hyperpolarized 13C‐labeled molecules in vivo.

Methods

Spin‐echo experiments with simultaneous acquisition of the free induction decay (FID) signal following the excitation pulse and the spin‐echo signal, were used to monitor hyperpolarized [1‐13C]lactate, [1‐13C]pyruvate, and the perfusion marker, [13C]HP001, following their intravenous injection into tumor‐bearing mice. Apparent T2 relaxation times and diffusion coefficients were also measured.

Results

An increasing tumor echo/FID ratio was observed for all three molecules, which could be explained by their extravasation into the tumor interstitial space, where T2 relaxation times were longer and diffusion coefficients smaller. Inhibition of the monocarboxylate transporter, which decreased by 40% the label exchange between pyruvate and lactate, reduced the increase in the echo/FID ratio for pyruvate and lactate, but not for HP001, demonstrating that some of the increase in the echo/FID ratio was due to cell uptake of lactate and pyruvate. The different relaxation and diffusion behavior of the intravascular and extravascular signals affected measurements of the apparent label exchange rate constants.

Conclusion

Simultaneous collection of both FID and echo signals can provide information on cell uptake thus giving further insight into the kinetics of hyperpolarized 13C label exchange. Care is needed when comparing exchange rate constants determined in spin‐echo‐based studies. Magn Reson Med 70:1200–1209, 2013. © 2012 Wiley Periodicals, Inc.
A trial of proficiency of nerve conduction: Greater standardization still needed
Authors: Dyck Peter J. , Albers James W. , Wolfe James , Bolton Charles F. , Walsh Nancy , Klein Christopher J. , Zafft Andrew J. , Russell James W. , Thomas Karen , Davies Jenny L. , Carter Rickey E. , Melton L. Joseph , Litchy William J. ,   the Clinical vs. Neurophysiology Trial 3 Investigators
Published: December 2012

Introduction

The aim of this study was to test the proficiency (accuracy among evaluators) of measured attributes of nerve conduction (NC).

Methods

Expert clinical neurophysiologists, without instruction or consensus development, from 4 different medical centers, independently assessed 8 attributes of NC in 24 patients with diabetes mellitus (DM) on consecutive days.

Results

No significant intraobserver differences between days 1 and 2 were found, but significant interobserver differences were seen. Use of standard reference values did not correct for these observed differences.

Conclusions

Interobserver variability was attributed to differences in performance of NC. It was of sufficient magnitude that it is of concern for the conduct of therapeutic trials. To deal with interrater variability in therapeutic trials, the same electromyographers should perform all NC assessments of individual patients or, preferably, NC procedures should be more standardized. A further trial is needed to test whether such standardization would eliminate interobserver variability. Muscle Nerve 48: 369–374, 2013
Spatially matched in vivo and ex vivo MR metabolic profiles of prostate cancer – investigation of a correlation with Gleason score
Authors: Selnæs Kirsten M. , Gribbestad Ingrid S. , Bertilsson Helena , Wright Alan , Angelsen Anders , Heerschap Arend , Tessem May‐Britt
Published: December 2012

MR metabolic profiling of the prostate is promising as an additional diagnostic approach to separate indolent from aggressive prostate cancer. The objective of this study was to assess the relationship between the Gleason score and the metabolic biomarker (choline + creatine + spermine)/citrate (CCS/C) measured by ex vivo high‐resolution magic angle spinning MRS (HR‐MAS MRS) and in vivo MRSI, and to evaluate the correlation between in vivo‐ and ex vivo‐measured metabolite ratios from spatially matched prostate regions. Patients (n = 13) underwent in vivo MRSI prior to radical prostatectomy. A prostate tissue slice was snap‐frozen shortly after surgery and the locations of tissue samples (n = 40) collected for ex vivo HR‐MAS were matched to in vivo MRSI voxels (n = 40). In vivo MRSI was performed on a 3T clinical MR system and ex vivo HR‐MAS on a 14.1T magnet. Relative metabolite concentrations were calculated by LCModel fitting of in vivo spectra and by peak integration of ex vivo spectra. Spearman's rank correlations (ρ) between CCS/C from in vivo and ex vivo MR spectra, and with their corresponding Gleason score, were calculated. There was a strong positive correlation between the Gleason score and CCS/C measured both in vivo and ex vivo (ρ = 0.77 and ρ = 0.69, respectively; p < 0.001), and between in vivo and ex vivo metabolite ratios from spatially matched regions (ρ = 0.67, p < 0.001). Our data indicate that MR metabolic profiling is a potentially useful tool for the assessment of cancer aggressiveness. Moreover, the good correlation between in vivo‐ and ex vivo‐measured CCS/C demonstrates that our method is able to bridge MRSI and HR‐MAS molecular analysis. Copyright © 2012 John Wiley & Sons, Ltd.
A finite difference method for the wide‐angle “parabolic” equation in a waveguide with downsloping bottom
Authors: Antonopoulou Dimitra C. , Dougalis Vassilios A. , Zouraris Georgios E.
Published: December 2012

We consider the third‐order wide‐angle “parabolic” equation of underwater acoustics in a cylindrically symmetric fluid medium over a bottom of range‐dependent bathymetry. It is known that the initial‐boundary‐value problem for this equation may not be well posed in the case of (smooth) bottom profiles of arbitrary shape, if it is just posed e.g. with a homogeneous Dirichlet bottom boundary condition. In this article, we concentrate on downsloping bottom profiles and propose an additional boundary condition that yields a well‐posed problem, in fact making it L2 ‐conservative in the case of appropriate real parameters. We solve the problem numerically by a Crank–Nicolson‐type finite difference scheme, which is proved to be unconditionally stable and second‐order accurate and simulates accurately realistic underwater acoustic problems. © 2012 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2013
Mechanical behavior, structure, and reinforcement processes of TEMPO‐oxidized cellulose reinforced poly(lactic) acid
Authors: Bulota Mindaugas , Vesterinen Arja‐Helena , Hughes Mark , Seppälä Jukka
Published: December 2012

Poly(lactic) acid (PLA) was reinforced with acetylated TEMPO‐oxidized fibrillated cellulose (TOFC) prepared from birch pulp. Composite films were studied using dynamic mechanical thermal analysis, differential scanning calorimetry (DSC), as well as static mechanical testing. The storage modulus as well as tensile strength of PLA was improved on the addition of 30 wt% of TOFC by approximately 50% and 40%, respectively. Thermal stability as well as strength properties in moist environments (up to 90% relative humidity) was significantly improved at 15, 20, 25, and 30 wt% of TOFC. DSC showed that crystallization from solution took place during preparation of the composite films and was much greater than melt crystallization. POLYM. COMPOS., 2012. © 2013 Society of Plastics Engineers
Novel polymer‐ceramic composites for protection against ballistic fragments
Authors: Naebe Minoo , Sandlin James , Crouch Ian , Fox Bronwyn
Published: December 2012

For the first time, internally reinforced aggregate polymer ceramic composites were evaluated against fragment simulating projectiles (FSPs) of various calibers to investigate their ballistic impact response. Samples were prepared by mechanically mixing B4C and cBN over a range of ratios and combinations with either thermosetting phenolic or epoxy resin and aramid pulp. Dry mixtures were then molded in a closed die using a heated platen press. The resulting tiles were then mounted as “strike faces” to an aramid backing material using an epoxy resin. Backed targets were tested in a fully instrumented firing range against 5.56 mm FSPs to test ballistic limit. A further series of tests using 7.62, 12.5, and 20 mm FSPs was conducted to examine round deformation across a range of fragments calibers. Round deformations were measured after impact and plotted against shot velocity. It was found that the polymer ceramic composite materials were effective round deformers and, like sintered ceramic strike faces, demonstrated improved ballistic performance at an equivalent areal density and impressive multihit capability. POLYM. COMPOS., 2012. © 2013 Society of Plastics Engineers
Copolymerization of a dendronized monomer with styrene and different acrylates: Determination of reactivity ratios
Authors: Krebs Anke , Bruchmann Bernd , Müller‐Cristadoro Anna , Al‐Hellani Rabie , Schlüter A. Dieter
Published: December 2012

The reactivity ratios for the copolymerization of a first‐generation dendronized monomer with styrene and different acrylates are determined. The obtained ratios as well as the copolymer compositions that can be expected are discussed in detail. The influence of the dendron on the polymerization potential of the monomer is estimated by comparing its reactivity to those of linear systems as well as using higher generations of the dendronized monomer. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013
Swelling of ultrathin crosslinked polyamide water desalination membranes
Authors: Chan Edwin P. , Young Allison P. , Lee Jung‐Hyun , Chung Jun Young , Stafford Christopher M.
Published: December 2012

We study the water swelling behavior of semiaromatic crosslinked polyamide (PA) ultrathin films to characterize the network properties of the polymer. Specifically, we use X‐ray reflectivity to measure film thickness increase and polymer density decrease of the PA films due to swelling. With the aid of a modified Flory–Rehner theory used to describe the constrained swelling behavior of polymer networks, we are able to extract the Flory interaction parameter and the monomer units between crosslinks by performing the swelling experiments at different levels of hydration. © 2012 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2013
Enhanced mechanical property of chitosan via blending with functional poly(ε‐caprolactone)
Authors: Gu Chunhua , Shi Weibin , Lang Meidong
Published: December 2012

Blends of chitosan and poly(ε‐caprolactone‐co‐2‐oxepane‐1,5‐dione) (PCO) were fabricated by solvent casting technique using 77% acetic acid as the cosolvent. The interactions between chitosan and PCO were analyzed by Fourier transform infrared spectroscopy, nuclear magnetic resonance, and differential scanning calorimetry. The miscibility became poorer with increase of PCO from 50% to 75%, which was supported by the Flory–Huggins interaction parameter and crystallinity of PCO. According to X‐ray pattern, crystallinity of CS became weaker when PCO content was improved. Results indicated that there existed stronger interactions in comparison with PCL/CS blends. Therefore, the addition of functional polyester PCO made the brittle chitosan ductile. The elongation was significantly prolonged to 21.60 ± 4.92% with the break stress maintaining about 32 MPa, better than that of PCL blends. The degradation behavior showed slower degradation rate compared with pure CS and the morphology was illustrated by scanning electron microscopy. © 2012 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2013
Functioning and Quality of Life in Adults with Mild‐to‐Moderate Osteogenesis Imperfecta
Authors: Balkefors Veronica , Mattsson Eva , Pernow Ylva , Sääf Maria
Published: December 2012

Purpose

The aim of this study was to describe physical activity, quality of and satisfaction with life, pain, joint mobility and muscle function in adults with mild‐to‐moderate osteogenesis imperfecta (OI) to form the basis of improved clinical care and physical therapy treatment.

Method

A total of 40 men and women aged between 21 and 71 years were identified and a prospective, cross‐sectional study was performed on 29 (18 women) included participants. The participants had to be able to walk and to have a diagnosis of mild‐to‐moderate OI. Self‐administered questionnaires and clinical examinations were used.

Results

Difficulties were found in all domains of the International Classification of Functioning, Activity and Health. Pain was reported in 25 of 29 participants and scoliosis was found in 23 participants. Difficulty to run was estimated in 18 participants. A total of 19 of 27 participants reported reaching the recommendations of 30 min of moderate‐intensity activity preferably every day. Life satisfaction was high even though health‐related quality of life, assessed with the Short Form 36, was significantly lower than the Swedish norm.

Conclusion

Impairments and activity limitations involved pain, scoliosis, contractures as well as trouble with running, heavy lifting, heavy work and sports. This study show that individuals with mild‐to‐moderate OI perceive themselves as having decreased health‐related quality of life and this seems to depend on decreased physical functioning. Despite that, as a group, they estimated high life satisfaction and 19 participants reported adhering to the general recommendation of 30 min of moderate‐intensity activity preferably every day. Copyright © 2012 John Wiley & Sons, Ltd.
Applicability of green fluorescence protein in the study of endothelin converting enzyme‐1c trafficking
Authors: Kuruppu Sanjaya , Tochon‐Danguy Nathalie , Ian Smith A.
Published: December 2012

Endothelin‐1 (ET‐1) is one of the most potent peptide vasoconstrictors known. It is produced upon the cleavage of its precursor big endothelin‐1 by endothelin converting enzyme‐1 (ECE‐1). Production of ET‐1 is thought to be dependent upon the expression of ECE‐1 at the cell surface. Therefore, mechanisms inducing the trafficking of ECE‐1 to the cell surface have been the focus of recent research. This research has identified phosphorylation of the cytoplasmic region of ECE‐1 as a main cellular signal inducing its trafficking to the cell surface. Previous studies have used green fluorescent protein (GFP) tagged ECE‐1 to monitor phosphorylation induced trafficking of ECE‐1 to the cell surface. However, it has been speculated that the addition of the GFP tag can itself alter enzyme activity and phosphorylation of ECE‐1, and hence the suitability of GFP or any other protein tag in studying ECE‐1 distribution and trafficking. ECE‐1c is the most widely expressed isoform in endothelial cells. We therefore expressed ECE‐1c with a GFP tag either at the N or C‐terminus of ECE‐1c. Catalytic activity and effect on protein kinase C (PKC) induced phosphorylation was compared between the two chimeras and wild‐type ECE‐1c. Our results indicate that positioning of the GFP tag on the C‐terminus abrogates activity without effecting PKC‐induced phosphorylation. However, GFP tag on the N‐terminus has the opposite effect. Results of this study shed light on the applicability of GFP or perhaps other protein tags in studying ECE‐1c distribution and trafficking.
Spectroscopically labeled peptaibiotic analogs: the 4‐nitrophenylalanine infrared absorption probe inserted at different positions into trichogin GA IV
Authors: Peggion Cristina , Biondi Barbara , De Zotti Marta , Oancea Simona , Formaggio Fernando , Toniolo Claudio
Published: December 2012

A set of three analogs of the 10‐residue, membrane‐active lipopeptaibiotic trichogin GA IV, labeled with the promising 4‐nitrophenylalanine IR absorption probe for local polarity, was synthesized by the solid‐phase methodology, chromatographically purified, and extensively characterized. A single residue modification was inserted near the N‐terminus, in the central region, or at the C‐terminus. A solution conformational analysis, carried out by FT‐IR absorption, CD, and 2D‐NMR combined with molecular dynamics calculations, indicates that the mono‐labeled analogs maintain the overall helical properties of the parent compound. Membrane permeabilization measurements and antimicrobial tests revealed that they possess membrane‐modifying properties andin vitroantibacterial activities analogous to those of the natural lipopeptaibiotic. Our IR absorption and attenuated total reflectance investigations in various environments, from which water was excluded for solubility reasons, showed that the 1350 cm−14‐nitrobenzyl band is a reporter group of rather limited sensitivity. Copyright © 2012 European Peptide Society and John Wiley & Sons, Ltd.
Anti‐Adipogenic Activity of Berberine is Not Mediated by the WNT/β‐Catenin Pathway
Authors: Bae Sungmin , Yoon Yoosik
Published: December 2012

Adipogenesis is a differentiation process from preadipocytes to adipocytes, accompanied by the inductions of adipogenic transcription factors and lipid metabolizing enzymes. Among cellular pathways regulating adipogenesis, the WNT/β‐catenin pathway is well‐known as a suppressor of adipogenesis. Berberine (BBR) is an isoquinoline alkaloid component of the medicinal plants including Coptis chinensis and Coptis japonica with diverse biological activities. This study was conducted to elucidate whether the anti‐adipogenic effect of BBR is mediated by the WNT/β‐catenin pathway. The results of the present study confirmed that BBR efficiently inhibited adipogenesis of 3T3‐L1 cells. However, the anti‐adipogenic effects of BBR were not accompanied by the modulations of the WNT/β‐catenin pathway members including WNT10B, LRP6, DVL2, GSK3β and β‐catenin. When β‐catenin was knocked down by its siRNA transfection, the anti‐adipogenic effects of BBR including the expression of adipogenic transcription factors and lipid metabolizing enzymes as well as the intracellular fat accumulation were not affected at all. The results of this study showed that the anti‐adipogenic effect of BBR is not mediated by the WNT/β‐catenin pathway. Copyright © 2012 John Wiley & Sons, Ltd.
Orographic precipitation across an island in southern Norway: model evaluation of time‐step precipitation
Authors: Barstad Idar , Caroletti Giulio N.
Published: December 2012

Observations of high spatio‐temporal resolution from a precipitation network across Stord Island, located off the west coast of southern Norway, are compared to state‐of‐the‐art numerical model simulations. The 12 week long observation period shows a clear orographic precipitation signal across the 10–15 km wide island (peak elevation 750 m). The model experiment designed to capture this signal is run with 9–3–1 km nested grid and results are compared with observations at different accumulation intervals. The total amount of precipitation over the 12 week period is underpredicted, even for the 1 km grid. The maximum precipitation intensity, however, is slightly overpredicted. Time‐step (5 s) precipitation from the model is also compared with observed intensities at the highest possible temporal resolution permitted by the rain collection method. The observations indicate that most of the precipitation is formed at intensities from 5 to 20 mm h−1. A smaller fraction of the precipitation is formed with intensities >20 mm h−1. The simulated precipitation at the 3 km grid did not reproduce at the correct intensities. The 1 km grid showed an improved tendency to produce the precipitation at the right intensities, but had too high maximum intensities. A test simulation where the intermediate grid had no cumulus parametrization was performed. Even though effects such as undercatchment and unresolved terrain influenced, it was concluded that the test run performed better than the control run. The investigation concluded that, in general, a 1 km grid is sufficient for capturing the most intensive precipitation event in a satisfying way.
Deconstructing the Hadley cell heat transport
Authors: Heaviside C. , Czaja A.
Published: December 2012

The mechanisms responsible for poleward atmospheric heat transport at low latitudes are examined in the European Centre for Medium‐Range Weather Forecasts (ECMWF) Re‐Analysis (ERA‐40) dataset. Deep meridional overturning circulations are found in regions experiencing frequent convection (i.e. the Indo‐Pacific ‘warm pool’) and it is suggested that these are the primary reason why atmospheric heat transport seems dominated by axisymmetric motions or ‘Hadley cell heat transport’. In contrast, the more complex distribution of meridional mass transport by the circulations over the ‘cold tongue’ regions (such as the eastern Atlantic area) and the presence of a pronounced minimum in moist static energy at mid‐levels constrain these regions to contribute little to poleward heat transport year round. Regions experiencing frequent convection do not, however, account for all the annual mean poleward atmospheric heat transport. At the Equator, an annual net southward transport of heat of about 0.4 PW (1 PW = 1015 W) is found, but the deep overturning cells found in the most convectively active regions contribute only 25% of this. This small contribution of ∼0.1 PW is understood to reflect a seasonal cancellation between large (∼1 PW) northward and southward heat transports in boreal winter and summer respectively. During December‐February, most of the cross‐equatorial heat transport is attributable to the convective regions, whereas in June‐August, only half is attributable to these regions. In this season, there is a significant amount of heat transport by the strong Somali jet associated with the Asian summer monsoon. Rather than attributing the net southward cross‐equatorial heat transport to asymmetries in the climatology associated with the northerly position of the intertropical convection zones throughout the year over the eastern Pacific and Atlantic oceans, our diagnostics suggest that the Somali jet is a significant contributor to the annual net southward atmospheric heat transport at the Equator.
International workshop on smalltalk technologies 2011 special issue
Authors: Plantec A. , Lagadec L.
Published: December 2012

Smalltalk is an exciting object‐oriented language in which even primitive values are uniformly handled as normal objects described by classes that one can browse and extend. Smalltalk was born during the seventies, but the ideas behind currently available implementations are still modern and innovative.

Smalltalk benefits from being a highly expressive language in which complex and powerful systems can emerge from the composition of simple building blocks. Thanks to its dynamic nature, fast prototyping and agile software development are made possible. Smalltalk also benefits from having powerful meta‐programming facilities. A program is able to query and to change its own structure and behavior. Smalltalk is not only a language but also an interactive system that is implemented in Smalltalk and that can be customized according to users needs.

This special issue presents four extended versions of research papers from the third International Workshop on Smalltalk Technologies (IWST) that was organized at Edinburgh on September 2011.

Johan Fabry et al. presented Phantom, an aspect language that includes recent research results in aspect interactions and reentrancy control. Phantom is designed to be optimized and compiled where possible.

Increasing use of reflection and meta‐programming techniques in real world applications underlines the need for more dynamic approaches. New approaches have shifted to object‐specific reuse. Jorge Ressia et al. proposed a new abstraction called a talent, which models features that are shared between objects of different class hierarchies.

Martin Dias et al. presented Fuel, a general‐purpose object serializer that focuses on speed, through a compact binary format and an efficient pickling algorithm. Fuel serializes any object, thus having a full‐featured language‐specific format.

Redesign of nontrivial software is often a challenge. Ciprian Teodorov et al. addressed physical‐design automation and presented a methodological approach relying on model‐driven engineering. Also, they summarized some lessons learned from the incremental redesign of Madeo, a toolkit that targets field‐programmable gate array design automation.

The goal of the IWST workshop series is to create and foster a forum around advances or experiences in Smalltalk. Each IWST workshop is organized as a collocated event of the European Smalltalk User Group annual conference. Copyright © 2012 John Wiley & Sons, Ltd.
Brief Report: Human Pluripotent Stem Cell Models of Fanconi Anemia Deficiency Reveal an Important Role for Fanconi Anemia Proteins in Cellular Reprogramming and Survival of Hematopoietic Progenitors
Authors: Yung Sun K. , Tilgner Katarzyna , Ledran Maria H. , Habibollah Saba , Neganova Irina , Singhapol Chatchawan , Saretzki Gabriele , Stojkovic Miodrag , Armstrong Lyle , Przyborski Stefan , Lako Majlinda
Published: December 2012

Fanconi anemia (FA) is a genomic instability disorder caused by mutations in genes involved in replication-dependant-repair and removal of DNA cross-links. Mouse models with targeted deletions of FA genes have been developed; however, none of these exhibit the human bone marrow aplasia. Human embryonic stem cell (hESC) differentiation recapitulates many steps of embryonic hematopoietic development and is a useful model system to investigate the early events of hematopoietic progenitor specification. It is now possible to derive patient-specific human-induced pluripotent stem cells (hiPSC); however, this approach has been rather difficult to achieve in FA cells due to a requirement for activation of FA pathway during reprogramming process which can be bypassed either by genetic complementation or reprogramming under hypoxic conditions. In this study, we report that FA-C patient-specific hiPSC lines can be derived under normoxic conditions, albeit at much reduced efficiency. These disease-specific hiPSC lines and hESC with stable knockdown of  FANCC  display all the in vitro hallmarks of pluripotency. Nevertheless, the disease-specific hiPSCs show a much higher frequency of chromosomal abnormalities compared to parent fibroblasts and are unable to generate teratoma composed of all three germ layers in vivo, likely due to increased genomic instability. Both FANCC-deficient hESC and hiPSC lines are capable of undergoing hematopoietic differentiation, but the hematopoietic progenitors display an increased apoptosis in culture and reduced clonogenic potential. Together these data highlight the critical requirement for FA proteins in survival of hematopoietic progenitors, cellular reprogramming, and maintenance of genomic stability.
Alcam Regulates Long-Term Hematopoietic Stem Cell Engraftment and Self-Renewal
Authors: Jeannet Robin , Cai Qi , Liu Hongjun , Vu Hieu , Kuo Ya-Huei
Published: December 2012

Hematopoietic stem cells (HSCs) reside in a specialized bone marrow (BM) microenvironment that supports the maintenance and functional integrity of long-term (LT)-HSCs throughout postnatal life. The objective of this work is to study the role of activated leukocyte cell adhesion molecule (Alcam) in HSC differentiation and self-renewal using an Alcam-null (Alcam−/−) mouse model. We show here that Alcam is differentially regulated in adult hematopoiesis and is highly expressed in LT-HSCs where its level progressively increases with age. Young adult Alcam−/− mice had normal homeostatic hematopoiesis and normal numbers of phenotypic HSCs. However, Alcam−/− HSCs had reduced long-term replating capacity in vitro and reduced long-term engraftment potential upon transplantation. We show that Alcam−/− BM contain a markedly lower frequency of long-term repopulating cells than wild type. Further, the long-term repopulating potential and engraftment efficiency of Alcam−/− LT-HSCs was greatly compromised despite a progressive increase in phenotypic LT-HSC numbers during long-term serial transplantation. In addition, an age-associated increase in phenotypic LT-HSC cellularity was observed in Alcam−/− mice. This increase was predominately within the CD150hi fraction and was accompanied by significantly reduced leukocyte output. Consistent with an aging-like phenotype, older Alcam−/− LT-HSCs display myeloid-biased repopulation activity upon transplantation. Finally, Alcam−/− LT-HSCs display premature elevation of age-associated gene expression, including Selp, Clu, Cdc42, and Foxo3. Together, this study indicates that Alcam regulates functional integrity and self-renewal of LT-HSCs.
A study on cooperative tap control method for voltage profile maintenance in distribution networks with distributed generators
Authors: Nguyen Tran , Tsuji Takao , Oyama Tsutomu , Hashiguchi Takuhei , Goda Tadahiro , Shinji Takao , Tsujita Shinsuke
Published: December 2012

The introduction of distributed generators (DGs) that can utilize renewable energy is of prime importance to solve the energy and environmental issues. When a distribution network has a large number of DGs, voltage maintenance becomes a serious problem. To solve this problem, we had proposed the ‘voltage profile control method’ using reactive power control of DGs. However, the control is limited to continuous reactive power control so far, and tap control has not been considered. It is important that the conventional voltage control equipment such as the load ratio tap changer (LRT) or step voltage regulator (SVR) is utilized in order to enhance the control efficiency of the voltage profile control method. Therefore, in this paper, we develop a new method that can realize a cooperative work between inverters and tap control of LRT and SVR. The proposed method is tested in 8‐ and 24‐node model systems and its effectiveness is shown. © 2012 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.
Accurate one‐terminal fault location algorithm based on the principle of short‐circuit calculation
Authors: Threevithayanon Wutthikorn , Hoonchareon Naebboon
Published: December 2012

An alternative method to find the line fault distance in a transmission network employing only one‐terminal measured data is presented. The proposed method applies Zbus for short‐circuit calculation to find the fault location on a transmission line without the necessity to know the fault type a priori. The well‐known drawback of the standard simple‐reactance one‐terminal algorithm, which neglects the effect of fault impedance, will be minimized by estimating the voltage drop at the fault location by employing the Zbus technique. Accuracy the proposed method is demonstrated using the short‐circuit simulation of the modified IEEE‐14 bus test system on MATLAB/Simulink and the Simpower Toolbox. Compared to the accuracy obtained from the standard one‐terminal algorithm, test results confirm substantially improved accuracy of the proposed method in all cases of the four types of fault categories: single line‐to‐ground fault; double line‐to‐ground fault; line‐to‐line fault; and balance three‐phase fault. While the accuracy has been significantly improved, especially for the case with a relatively high fault impedance, also the simplicity in the involved computation is well preserved when compared to other iterative‐based techniques. © 2012 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.
Image‐based visual target following for a nonholonomic wheeled mobile robot with a single fixed camera
Authors: Ito Masahide , Hiratsuka Takahiro , Shibata Masaaki
Published: December 2012

This paper addresses the problem of visual target following for a nonholonomic wheeled mobile robot with a single fixed camera. For the problem, we propose a control scheme composed of vision‐based trajectory planning and tracking control. We present online trajectory planning based on image‐based visual servoing. The key idea is to compensate the target object motion. In particular, we focus on visual feature motion resulting from the target object motion. Tracking control to the generated trajectory can therefore achieve visual target following precisely even if the target object is moving. Our proposed scheme can be applied to, e.g. robotic systems for autonomous guard and observation. The effectiveness of the control system is evaluated experimentally. © 2012 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.
Resource allocation with interference mitigation in femtocellular networks
Authors: Ali Najah Abu , Ouda Mahmoud , Hassanein Hossam , Kubbar Osama
Published: December 2012

The introduction of femtocells enabled high data rates and better indoor coverage without the need for expanding or increasing the density of cellular networks deployment or upgrading the cellular network infrastructure. Despite this direct advantage, the introduction of femtocells challenges traditional interference mechanisms because of the ad hoc and dense nature of femtocell deployment. In this paper, we propose an optimal downlink frequency assignment scheme. The proposed algorithm is modeled as a transportation problem to optimally allocate frequency subcarriers with the objective of maximizing the system capacity. The scheme can be used as a benchmark for assessing the suitability of interference mitigation schemes in femtocellular networks.Copyright © 2012 John Wiley & Sons, Ltd.
Heavy‐tailed densities
Authors: Rojo Javier
Published: December 2012

The concept of heavy‐ or long‐tailed densities (or distributions) has attracted much well‐deserved attention in the literature. A quick search in Google using the keywords long‐tailed statistics retrieves almost 12 million items. The concept has become a pillar of the theory of extremes, and through its connection with outlier‐prone distributions, long‐tailed distributions also play a central role in the theory of robustness.

The concept of tail heaviness is by now ubiquitous, appearing in a diverse set of disciplines that includes: economics, communications, atmospheric sciences, climate modeling, social sciences, physics, modeling of complex systems, etc. Nevertheless, the precise meaning of ‘long‐’ or ‘heavy tails’ remains somewhat elusive. Thus, in a substantial portion of the early literature, long‐tailedness meant that the underlying distribution was capable of producing anomalous observations in the sense that they were ‘too far’ from the main body of observations. Implicit in these informal definitions was the notion that any distribution that behaved that way had to do so because its tails were longer than those of the normal distribution.

This paper discusses tail orderings and several approaches for the classification of probability distributions according to tail heaviness. It is concluded that an approach based on the limiting behavior of the residual life function, and its corresponding characterizations based on functions of regular variation and asymptotic distribution of extreme spacings, provides the more natural and illuminating concepts of tail behavior. WIREs Comput Stat 2013, 5:30–40. doi: 10.1002/wics.1236

This article is categorized under:

Statistical and Graphical Methods of Data Analysis > Nonparametric Methods

Data: Types and Structure > Traditional Statistical Data
Quadratic programming algorithms for ensemble models
Authors: Xu Jie , Gray J. Brian
Published: December 2012

Ensemble models, such as bagging, random forests, and boosting, have better predictive accuracy than single classifiers. These ensembles typically consist of hundreds of single classifiers, which make future predictions and model interpretation much more difficult than for single classifiers. Recently, research efforts have been directed toward improving ensembles by reducing their size while increasing or maintaining their predictive accuracy. In this article, we review recently proposed methods based on quadratic programming techniques for accomplishing these goals. WIREs Comput Stat 2013, 5:41–47. doi: 10.1002/wics.1237

This article is categorized under:

Statistical Learning and Exploratory Methods of the Data Sciences > Modeling Methods

Algorithms and Computational Methods > Quadratic and Nonlinear Programming
Diagnostic tools for hierarchical linear models
Authors: Loy Adam , Hofmann Heike
Published: December 2012

Hierarchical structures are omnipresent in today's society—this is reflected in the data that we collect on all aspects of this society. Hierarchical linear models allow a representation of structural levels in a statistical modeling framework. Diagnostic tools are used to assess the quality of model estimation and explore features of the data not well described by the model. Residual and influence diagnostics are familiar tools for the classical regression model with independent observations. For hierarchical linear models, these diagnostic tools must be adjusted to reflect the dependence introduced by the nested data structure. Residual analysis now includes the assessment of distributional assumptions at each level of the model. This requires the use of level‐dependent residual quantities. Similarly, the parameter estimates may be influenced at each level of the model, requiring influence diagnostics that can pinpoint specific levels of the model, as well as specific aspects of the model. We present an overview of the diagnostic tools available for hierarchical linear models that are familiar from linear models. Additionally, we discuss the utility of the lineup protocol for residual analysis with complex models.WIREs Comput Stat2013, 5:48–61. doi: 10.1002/wics.1238

This article is categorized under:

Statistical Models > Bayesian Models

Statistical and Graphical Methods of Data Analysis > Bayesian Methods and Theory

Statistical and Graphical Methods of Data Analysis > Modeling Methods and Algorithms

Statistical and Graphical Methods of Data Analysis > Statistical Graphics and Visualization
Partial least squares algorithms and methods
Authors: Esposito Vinzi Vincenzo , Russolillo Giorgio
Published: December 2012

Partial least squares (PLS) refers to a set of iterative algorithms based on least squares that implement a broad spectrum of both explanatory and exploratory multivariate techniques, from regression to path modeling, and from principal component to multi‐block data analysis. This article focuses on PLS regression and PLS path modeling, which are PLS approaches to regularized regression and to predictive path modeling. The computational flows and the optimization criteria of these methods are reviewed in detail, as well as the tools for the assessment and interpretation of PLS models. The most recent developments and some of the most promising on going researches are enhanced.WIREs Comput Stat2013, 5:1–19. doi: 10.1002/wics.1239

This article is categorized under:

Statistical Learning and Exploratory Methods of the Data Sciences > Exploratory Data Analysis

Statistical and Graphical Methods of Data Analysis > Multivariate Analysis

Statistical Models > Linear Models

Algorithms and Computational Methods > Least Squares
Hanging Dot Plots and identifying outliers in samples from asymmetrical populations with Hubert and Vandervieren's robust outlier rule
Authors: Bradstreet Thomas E. , Gillespie Amy , Zhang Shuping , Zhu Xingshu
Published: December 2012

Visualizing individual data, empirical distributions, and summary statistics for small to moderate sized samples (≤ 500) is critical in early phases of drug research. We developed a customized SAS® macro, %HangingDotPlot, which displays dot plots with parametric or distribution‐free descriptive statistics and confidence intervals simultaneously on the same page for multiple groups of data. Potential statistical outliers are identified with a fence rule adapted from an adjusted box plot for skewed distributions, which incorporates the medcouple, a robust measure of skewness. WIREs Comput Stat 2013, 5:62–67. doi: 10.1002/wics.1241

This article is categorized under:

Statistical and Graphical Methods of Data Analysis > Statistical Graphics and Visualization
Examples of understanding safety data using graphical methods
Authors: Anziano Richard , Gordon Robert
Published: December 2012

Cardiac and hepatic safety are important considerations in drug development. This article focuses on the examination of laboratory and electrocardiogram data using graphical approaches that enable a better understanding of the data. Useful general principles to keep in mind when developing graphics are followed by sections on cardiovascular and hepatic safety. WIREs Comput Stat 2013, 5:78–95. doi: 10.1002/wics.1243

This article is categorized under:

Applications of Computational Statistics > Clinical Trials

Statistical Learning and Exploratory Methods of the Data Sciences > Exploratory Data Analysis

Data: Types and Structure > Data Preparation and Processing

Statistical and Graphical Methods of Data Analysis > Statistical Graphics and Visualization
Monitoring the polyamide 11 degradation by thermal properties and X‐ray fluorescence spectrometry allied to chemometric methods
Authors: Domingos Eloilson , Pereira Thieres M. C. , Filgueiras Paulo R. , Bueno Maria Izabel M. S. , de Castro Eustáquio V. R. , Guimarães Regina C. L. , de Sena Geovane L. , Rocha Werickson F.C. , Romão Wanderson
Published: December 2012

The influence of temperature (110 and 120 °C) on the ageing of piping made from polyamide 11 (PA‐11) containing 10–12% of plasticizer was studied using deionized water (pH ≈ 7.0). A clean analytical methodology has been employed for quality control of polymeric materials: energy‐dispersive X‐ray fluorescence spectrometry (ED‐XRF). It provides a fast and suitable technique to characterize chemical elements because of its multielemental capability, good sensitivity, high precision, short analytical time, and nondestructive nature. Herein, the content of additive in PA‐11 was monitored from ED‐XRF measurements where the abundance of the S line is directly related to the ageing time, agreeing with the thermogravimetric analysis. The XRF data were allied to chemometric treatment to classify PA‐11 samples according to the amount of additive and weight average molar mass change, predicting the ageing time, and viscosity values of PA‐11. Therefore, the XRF can be used as a clean analytical methodology to monitor the PA‐11 degradation, thus eliminating the use of toxic organic solvents (necessary to viscosity measurements) and reducing the working time. Also, the effect of hydrolysis on the structure over time and the material morphology were monitored through measurements of dynamic mechanical analysis and differential scanning calorimetry. Copyright © 2012 John Wiley & Sons, Ltd.
Factors Associated with Incomplete DASH Questionnaires
Authors: Bot Arjan G. J. , Ferree Steven , Neuhaus Valentin , Ring David
Published: December 2012

Background

Missing data are unavoidable in clinical research. Older age, female gender, and fewer years of education are risk factors for missing items in a questionnaire. This study assessed the differences between patients with complete and incomplete Disabilities of the Arms, Shoulder and Hand (DASH) questionnaires in terms of demographics and psychological factors.

Methods

We analyzed a convenience sample of 1,204 patients enrolled in eight prospective studies. The DASH and the Pain Catastrophizing Scale were completed by all patients. The Center for Epidemiologic Studies Depression scale, Patient Health Questionnaire, Pain Anxiety Symptoms Scale, and an ordinal pain scale were completed by 745, 493, 545, and 391 patients, respectively. Bivariate analysis and binary logistic regression were used to determine risk factors for incomplete (one or more unanswered question) or invalid (more than three unanswered questions) DASH questionnaires.

Results

Thirty-one percent of patients did not complete all questions on the DASH. Patients with an incomplete DASH were older, had fewer years of education, and had higher levels of catastrophic thinking, depression, and pain anxiety. Age and catastrophic thinking were retained in the best logistic regression models of predictors of both incomplete and invalid DASH questionnaires.

Conclusions

The observation that patients who complete disability questionnaires are different from patients who do not may affect the interpretation of clinical research. Computer adaptive testing may be preferable to avoid incomplete questionnaires. Level of Evidence: Prognostic Level II.
Demographic group differences in adolescents' time attitudes
Authors: Andretta James R. , Worrell Frank C. , Mello Zena R. , Dixson Dante D. , Baik Sharon H.
Published: December 2012

In the present study, we examined demographic differences in time attitudes in a sample of 293 adolescents. Time attitudes were measured using the Adolescent Time Attitude Scale (Mello & Worrell, 2007; Worrell, Mello, & Buhl, 2011), which assesses positive and negative attitudes toward the past, the present, and the future. Generally, African Americans and Asian Americans reported higher scores for negative time attitudes and lower scores for positive time attitudes than European Americans and Latinos, with medium sizes. Adolescents in the low socioeconomic status group reported a less favorable evaluation of their past than middle and high SES peers, but there were no meaningful differences in time attitudes by gender. Findings indicate that middle SES adolescents, high school juniors and seniors, Latinos, and European Americans had higher representation in positive time attitude clusters (i.e., Positives and Balanced) than high SES adolescents, high school freshmen and sophomores, and African Americans.