bluuebunny/crossref_metadata_2025 huggingface dataset:
Neural response dynamics of spiking and local field potential activity depend on CRT monitor refresh rate in the tree shrew primary visual cortex
Authors: Veit Julia , Bhattacharyya Anwesha , Kretz Robert , Rainer Gregor
Published: August 2011

Entrainment of neural activity to luminance impulses during the refresh of cathode ray tube monitor displays has been observed in the primary visual cortex (V1) of humans and macaque monkeys. This entrainment is of interest because it tends to temporally align and thus synchronize neural responses at the millisecond timescale. Here we show that, in tree shrew V1, both spiking and local field potential activity are also entrained at cathode ray tube refresh rates of 120, 90, and 60 Hz, with weakest but still significant entrainment even at 120 Hz, and strongest entrainment occurring in cortical input layer IV. For both luminance increments (“white” stimuli) and decrements (“black” stimuli), refresh rate had a strong impact on the temporal dynamics of the neural response for subsequent luminance impulses. Whereas there was rapid, strong attenuation of spikes and local field potential to prolonged visual stimuli composed of luminance impulses presented at 120 Hz, attenuation was nearly absent at 60-Hz refresh rate. In addition, neural onset latencies were shortest at 120 Hz and substantially increased, by ∼15 ms, at 60 Hz. In terms of neural response amplitude, black responses dominated white responses at all three refresh rates. However, black/white differences were much larger at 60 Hz than at higher refresh rates, suggesting a mechanism that is sensitive to stimulus timing. Taken together, our findings reveal many similarities between V1 of macaque and tree shrew, while underscoring a greater temporal sensitivity of the tree shrew visual system.
Reward skewness coding in the insula independent of probability and loss
Authors: Burke Christopher J. , Tobler Philippe N.
Published: August 2011

Rewards in the natural environment are rarely predicted with complete certainty. Uncertainty relating to future rewards has typically been defined as the variance of the potential outcomes. However, the asymmetry of predicted reward distributions, known as skewness, constitutes a distinct but neuroscientifically underexplored risk term that may also have an impact on preference. By changing only reward magnitudes, we study skewness processing in equiprobable ternary lotteries involving only gains and constant probabilities, thus excluding probability distortion or loss aversion as mechanisms for skewness preference formation. We show that individual preferences are sensitive to not only the mean and variance but also to the skewness of predicted reward distributions. Using neuroimaging, we show that the insula, a structure previously implicated in the processing of reward-related uncertainty, responds to the skewness of predicted reward distributions. Some insula responses increased in a monotonic fashion with skewness (irrespective of individual skewness preferences), whereas others were similarly elevated to both negative and positive as opposed to no reward skew. These data support the notion that the asymmetry of reward distributions is processed in the brain and, taken together with replicated findings of mean coding in the striatum and variance coding in the cingulate, suggest that the brain codes distinct aspects of reward distributions in a distributed fashion.
Rebound excitation triggered by synaptic inhibition in cerebellar nuclear neurons is suppressed by selective T-type calcium channel block
Authors: Boehme Rebecca , Uebele Victor N. , Renger John J. , Pedroarena Christine
Published: August 2011

Following hyperpolarizing inputs, many neurons respond with an increase in firing rate, a phenomenon known as rebound excitation. Rebound excitation has been proposed as a mechanism to encode and process inhibitory signals and transfer them to target structures. Activation of low-voltage-activated T-type calcium channels and the ensuing low-threshold calcium spikes is one of the mechanisms proposed to support rebound excitation. However, there is still not enough evidence that the hyperpolarization provided by inhibitory inputs, particularly those dependent on chloride ions, is adequate to deinactivate a sufficient number of T-type calcium channels to drive rebound excitation on return to baseline. Here, this issue was investigated in the deep cerebellar nuclear neurons (DCNs), which receive the output of the cerebellar cortex conveyed exclusively by the inhibitory Purkinje cells and are also known to display rebound excitation. Using cerebellar slices and whole cell recordings of large DCNs, we show that a novel piperidine-based compound that selectively antagonizes T-type calcium channel activity, 3,5-dichloro- N-[1-(2,2-dimethyl-tetrahydropyran-4-ylmethyl)-4-fluoro-piperidin-4-ylmethyl]-benzamide (TTA-P2), suppressed rebound excitation elicited by current injection as well as by synaptic inhibition, whereas other electrophysiological properties of large DCNs were unaltered. Furthermore, TTA-P2 suppressed transient high-frequency rebounds found in DCNs with low-threshold spikes as well as the slow rebounds present in DCNs without low-threshold spikes. These findings demonstrate that chloride-dependent synaptic inhibition effectively triggers T-type calcium channel-mediated rebounds and that the latter channels may support slow rebound excitation in neurons without low-threshold spikes.
On the Usage of GPUs for Efficient Motion Estimation in Medical Image Sequences
Authors: Thiyagalingam Jeyarajan , Goodman Daniel , Schnabel Julia A. , Trefethen Anne , Grau Vicente
Published: August 2011

Images are ubiquitous in biomedical applications from basic research to clinical practice. With the rapid increase in resolution, dimensionality of the images and the need for real-time performance in many applications, computational requirements demand proper exploitation of multicore architectures. Towards this, GPU-specific implementations of image analysis algorithms are particularly promising. In this paper, we investigate the mapping of an enhanced motion estimation algorithm to novel GPU-specific architectures, the resulting challenges and benefits therein. Using a database of three-dimensional image sequences, we show that the mapping leads to substantial performance gains, up to a factor of 60, and can provide near-real-time experience. We also show how architectural peculiarities of these devices can be best exploited in the benefit of algorithms, most specifically for addressing the challenges related to their access patterns and different memory configurations. Finally, we evaluate the performance of the algorithm on three different GPU architectures and perform a comprehensive analysis of the results.
Mutual Coupling Effect on Ultrawideband Linear Antenna Array Performance
Authors: Ahmed Osama , Sebak Abdel-Razik
Published: August 2011

This paper studies the mutual coupling effect between array elements of two- and four-element ultrawideband (UWB) linear arrays on their performances. For simplicity, it is assumed that both antenna arrays are fed by independent microstrip lines with the same power amplitudes and equal phases. From our study, array bandwidth improvement is achieved for both array types when the mutual coupling is strong enough or interelement spacing is small. The mutual coupling also enhances the array realized gain especially in the midfrequency band (5–8.5 GHz) while it deteriorates the gain outside that frequency range. Proper tuning for interelement spacing with enough mutual coupling enhances the array realized gain at most frequencies and makes it more stable across the desired frequency range. From the radiation pattern results, the grating lobes appear in UWB arrays when the element spacing is greater than two wavelengths at the upper edge frequency, 10.6 GHz, or half wavelength at the lower edge frequency 3.1 GHz. Two fabricated array prototypes with corporate feed are fabricated and tested to validate the theoretical analysis. The effect of usingT-junction power divider is clear on the reflection coefficient|S11|. Both numerically simulated and experimental results successfully demonstrate our analysis.
NF-B-Inducing Kinase Increases Renal Tubule Epithelial Inflammation Associated with Diabetes
Authors: Zhao Yanhua , Banerjee Srijita , LeJeune Wanda S. , Choudhary Sanjeev , Tilton Ronald G.
Published: August 2011

The impact of increased NF-κB-inducing kinase (NIK), a key component of the NF-κB activation pathways, on diabetes-induced renal inflammation remains unknown. We overexpressed NIK wild type (NIKwt) or kinase-dead dominant negative mutants (NIKdn) in HK-2 cells and demonstrated that RelB and p52, but not RelA, abundance and DNA binding increased in nuclei of NIKwt but not NIKdn overexpressed cells, and this corresponded with increases in multiple proinflammatory cytokines. Since TRAF3 negatively regulates NIK expression, we silenced TRAF3 by >50%; this increased nuclear levels of p52 and RelB, and transcript levels of proinflammatory cytokines and transcription factors. In HK-2 cells and mouse primary proximal tubule epithelial cells treated with methylglyoxal-modified albumin, multiple proinflammatory cytokines and NIK were increased in association with increased nuclear RelB and p52. These observations indicate that NIK regulates proinflammatory responses of renal proximal tubular epithelial cells via mechanisms involving TRAF3 and suggest a role for NF-κB noncanonical pathway activation in modulating diabetes-induced inflammation in renal tubular epithelium.
H(·, ·)‐Cocoercive Operator and an Application for Solving Generalized Variational Inclusions
Authors: Ahmad Rais , Dilshad Mohd , Wong Mu-Ming , Yao Jen-Chin
Published: August 2011

The purpose of this paper is to introduce a new H(·, ·)‐cocoercive operator, which generalizes many existing monotone operators. The resolvent operator associated
with H(·, ·)‐cocoercive operator is defined, and its Lipschitz continuity is presented. By using techniques of resolvent operator, a new iterative algorithm for solving generalized variational inclusions is constructed. Under some suitable conditions, we prove the convergence of iterative sequences generated by the algorithm. For illustration, some examples are given.
Antigenic and Genotypic Similarity between Primary Glioblastomas and Their Derived Neurospheres
Authors: Caldera Valentina , Mellai Marta , Annovazzi Laura , Piazzi Angela , Lanotte Michele , Cassoni Paola , Schiffer Davide
Published: August 2011

Formation of neurospheres (NS) in cultures of glioblastomas (GBMs), with self-renewal, clonogenic capacities, and tumorigenicity following transplantation into immunodeficient mice, may denounce the existence of brain tumor stem cells (BTSCs) in vivo. In sixteen cell lines from resected primary glioblastomas, NS showed the same genetic alterations as primary tumors and the expression of stemness antigens. Adherent cells (AC), after adding 10% of fetal bovine serum (FBS) to the culture, were genetically different from NS and prevailingly expressed differentiation antigens. NS developed from a highly malignant tumor phenotype with proliferation, circumscribed necrosis, and high vessel density. Beside originating from transformed neural stem cells (NSCs), BTSCs may be contained within or correspond to dedifferentiated cells after mutation accumulation, which reacquire the expression of stemness antigens.
Minimally Invasive Surgery for Colorectal Cancer: Past, Present, and Future
Authors: Holder-Murray J. , Dozois E. J.
Published: August 2011

A rapid progression from conventional open surgery to minimally invasive approaches in the surgical management of colorectal cancer has occurred over the last 2 decades. Initial concerns that this new approach was oncologically inferior to open surgery were ultimately refuted when several prospective randomized trials concluded that laparoscopic colectomy could achieve similar oncologic outcomes to open surgery. On the contrary, level 1 data has not yet matured regarding the oncologic safety of minimally invasive approaches for rectal cancer. We review the published literature pertaining to the evolution of minimally invasive techniques used to treat colorectal cancer surgery, including barriers to adoption, and the prospects for future advances related to innovative techniques.
Transplantation Tolerance Induced in Humans at the Fetal or the Neonatal Stage
Authors: Touraine Jean-Louis , Sanhadji Kamel
Published: August 2011

Patients transplanted with HLA-mismatched stem cells from fetal livers develop transplantation tolerance to donor antigens. Engraftment needs no conditioning regimen prior to transplantation in neonates with severe combined immunodeficiency disease or in human fetal patients having not yet developed any immune maturity, especially T-cell differentiation. The chimeric patients have donor-derived T lymphocytes which progressively demonstrate positive interactions with other host cells. They also can be shown to be tolerant toward both host and donor antigens. The latter tolerance relies upon clonal deletion from the T-cell repertoire, and it results from the contact between thymocytes of donor origin and dendritic cells or macrophages also deriving from donor stem cells. The former tolerance does not imply clonal deletion of T-cells with host reactivity. Numerous T-cells recognizing the allogeneic, host-type antigens are identified in these patients, but these cells are anergized, following interaction with epithelial cells of the host thymus. Induction of transplantation tolerance at the fetal stage requires minimal engraftment only; in the future it will be possible to further amplify the clinical benefit, using additional cell transplants after birth.
Multiparameter Inversion: Cramer's Rule for Pseudodifferential Operators
Authors: Nammour Rami , Symes William W.
Published: August 2011

Linearized multiparameter inversion is a model-driven variant of amplitude-versus-offset analysis, which seeks to separately account for the influences of several model parameters on the seismic response. Previous approaches to this class of problems have included geometric optics-based (Kirchhoff, GRT) inversion and iterative methods suitable for large linear systems. In this paper, we suggest an approach based on the mathematical nature of the normal operator of linearized inversion—it is a scaling operator in phase space—and on a very old idea from linear algebra, namely, Cramer's rule for computing the inverse of a matrix. The approximate solution of the linearized multiparameter problem so produced involves no ray theory computations. It may be sufficiently accurate for some purposes; for others, it can serve as a preconditioner to enhance the convergence of standard iterative methods.
Embedded Spiral Microstrip Implantable Antenna
Authors: Huang Wei , Kishk Ahmed A.
Published: August 2011

A miniaturized embedded spiral-shaped microstrip antenna simulated within a block of 2/3 human muscle phantom is designed for implanted cardiac pacemaker. The new design not only achieves the good matching at the required 403 MHz but also obtains 57% size reduction over the existing design. The reflection coefficients are measured in both free space and in the human-tissue-equivalent dielectric liquid. Good agreement is achieved between simulated results and the experimental results.
Fractionation of Volatile Constituents fromCurcumaRhizome by Preparative Gas Chromatography
Authors: Yang F. Q. , Wang H. K. , Chen H. , Chen J. D. , Xia Z. N.
Published: August 2011

A preparative gas chromatography (pGC) method was developed for the separation of volatile components from the methanol extract ofCurcumarhizome. The compounds were separated on a stainless steel column packed with 10% OV-101 (3 m × 6 mm, i.d.), and then, the effluent was split into two gas flows. One percent of the effluent passed to the flame ionization detector (FID) for detection and the remaining 99% were directed to the fraction collector. Five volatile compounds were collected from the methanol extract ofCurcumarhizome (5 g/mL) after 83 single injections (20 uL) with the yield of 5.1–46.2 mg. Furthermore, the structures of the obtained compounds were identified asβ-elemene, curzerene, curzerenone, curcumenol, and curcumenone by MS and NMR spectra, respectively.
Nonimmune Cells Contribute to Crosstalk between Immune Cells and Inflammatory Mediators in the Innate Response toTrypanosoma cruziInfection
Authors: Aoki Maria Pilar , Carrera-Silva Eugenio Antonio , Cuervo Henar , Fresno Manuel , Gironès Núria , Gea Susana
Published: August 2011

Chagas myocarditis, which is caused by infection with the intracellular parasiteTrypanosoma cruzi, remains the major infectious heart disease worldwide. Innate recognition through toll-like receptors (TLRs) on immune cells has not only been revealed to be critical for defense againstT. cruzibut has also been involved in triggering the pathology. Subsequent studies revealed that this parasite activates nucleotide-binding oligomerization domain- (NOD-)like receptors and several particular transcription factors in TLR-independent manner. In addition to professional immune cells,T. cruziinfects and resides in different parenchyma cells. The innate receptors in nonimmune target tissues could also have an impact on host response. Thus, the outcome of the myocarditis or the inflamed liver relies on an intricate network of inflammatory mediators and signals given by immune and nonimmune cells. In this paper, we discuss the evidence of innate immunity to the parasite developed by the host, with emphasis on the crosstalk between immune and nonimmune cell responses.
Epithelial Protein-Tyrosine Phosphatase 1B Contributes to the Induction of Mammary Tumors by HER2/Neu but Is Not Essential for Tumor Maintenance
Authors: Balavenkatraman Kamal K. , Aceto Nicola , Britschgi Adrian , Mueller Urs , Bence Kendra K. , Neel Benjamin G. , Bentires-Alj Mohamed
Published: August 2011

Protein-tyrosine phosphatase 1B (PTP1B), a well-established metabolic regulator, plays an important role in breast cancer. Using whole-body PTP1B knockout mice, recent studies have shown that PTP1B ablation delays HER2/Neu-induced mammary cancer. Whether PTP1B plays a cell-autonomous or a noncell-autonomous role in HER2/Neu-evoked tumorigenesis and whether it is involved in tumor maintenance was unknown. We generated mice expressing HER2/Neu and lacking PTP1B specifically in the mammary epithelium. We found that mammary-specific deletion of PTP1B delays the onset of HER2/Neu-evoked mammary tumors, establishing a cell autonomous role for PTP1B in such neoplasms. We also deleted PTP1B in established mouse mammary tumors or depleted PTP1B in human breast cancer cell lines grown as xenografts. PTP1B inhibition did not affect tumor growth in either model showing that neither epithelial nor stromal PTP1B is necessary for tumor maintenance. Taken together, our data show that despite the PTP1B contribution to tumor onset, it is not essential for tumor maintenance. This suggests that PTP1B inhibition could be effective in breast tumor prevention. Mol Cancer Res; 9(10); 1377–84. ©2011 AACR.
Hypokalemia Is Associated with Increased Mortality Rate in Chronic Hemodialysis Patients
Authors: Hwang Jyh-Chang , Wang Charn-Ting , Chen Chien-An , Chen Hung-Chun
Published: August 2011

Background: Both hypokalemia (hypoK) and hyperkalemia (hyperK) are life-threatening to hemodialysis (HD) patients. This study was conducted to compare their clinical characteristics and long-term survival. Methods: Patients were divided into three groups according to the last mid-week predialysis serum potassium concentrations: hypoK (<3.5 mEq/l), normoK (between 3.5 and 5.5 mEq/l), and hyperK (>5.5 mEq/l). The maximal duration of the follow-up period was 54 months. Results: Compared with the hyperK group,patients in the hypoK group were older (p <0.05), had a higher incidence of comorbidity factors, less body weight gain prior to HD (p < 0.05), lower body mass index (BMI, p < 0.05), and higher BUN to creatinine ratio and hs-CRP (p < 0.05). The serum albumin and prealbumin concentrations were also lowest in the hypoK group, compared with the normoK and hyperK groups, respectively (all p < 0.001). A similar finding was also obtained for the normalized protein catabolism rate (nPCR, p < 0.001) among the three groups. Positive linear correlations between serum albumin and potassium concentration were only found in the hypoK and normoK groups (p < 0.001). Multiple logistic regression analysis showed that hypoalbuminemia, low BUN, and phosphate concentrations were significantly correlated with hypoK. HypoK patients also had a lower cumulative survival rate than hyperK patients. Conclusion: HypoK HD patients, with lower serum levels of albumin, prealbumin, nPCR, and BMI, but higher level of hs-CRP, showed a malnutritional and inflammatory status, and caused increased mortality rate.
Postnatal Renal Abnormalities in Rats Exposed to Losartan during Lactation
Authors: Marin Evelyn Cristina Santana , Francescato Heloísa Della Coletta , da Silva Cleonice Giovanini Alves , Costa Roberto Silva , Coimbra Terezila Machado
Published: August 2011

Background/Aims: Rats exposed to losartan during lactation exhibit progressive changes in renal function and structure. This study analyzed the early events in pups from dams that received losartan during lactation. Methods: Male Wistar rats from dams that received 2% sucrose (control, n = 25) or losartan (100 mg/kg/day) diluted in 2% sucrose (n = 33) during lactation were anesthetized 21 days after birth. Blood and urine samples were collected to assess renal function, and kidneys were removed for histological, immunohistochemical, Western blot, lipid peroxidation and glutathione analyses. Results: The group exposed to losartan exhibited increased albuminuria and fractional sodium and potassium excretion, decreased glomerular area and interstitial expansion. Immunohistochemical analyses demonstrated increased tubulointerstitial macrophage infiltration, apoptosis and increased vimentin and α-smooth-muscle-actin expression in animals exposed to losartan. In addition, the glomeruli of animals exposed to losartan exhibited increased peripheral desmin expression and reduced glomerular epithelial protein 1 and podocin expression compared to controls. Lastly, renal lipid peroxidation and glutathione levels were higher in the losartan-treated pups. Conclusion: Pups exposed to losartan during lactation exhibited adverse changes in renal function and structure, and tubulointerstitial inflammation at 21 days of age that were associated with apoptosis and oxidative stress.
Spinal Cord Stimulation and Cerebral Hemodynamics: Updated Mechanism and Therapeutic Implications
Authors: Visocchi Massimiliano , Della Pepa Giuseppe Maria , Esposito Giuseppe , Tufo Tommaso , Zhang Wenchuan , Li Shiting , Zhong Jun
Published: August 2011

The effects of spinal cord stimulation (SCS) on cerebral blood flow (CBF) are well known based on experimental investigations, and its vasodilator effect on peripheral arteries is widely used in clinical settings in the treatment of peripheral vascular disease. Since Hosobuchi’s [Appl Neurophysiol 1985;48:372–376] first observations on the effects of SCS on CBF were published 22 years ago, many advances have been made in understanding SCS-mediated effects on CBF. This paper reviews the main laboratory observations and analyzes the most significant neurophysiological theories on the SCS-mediated effect on CBF. Most significant experimental data have been discussed, with specific reference to possible mechanisms such as ‘functional reversible sympathectomy’, cerebral infarction and related ischemic edema, hemodynamic deterioration in experimental combined ischemic-traumatic brain injury and cerebral vasospasm. The authors revised the published experiences in humans with hypoperfusion syndromes and ‘adjuvant’ locoregional CBF increase in chemotherapy of brain tumors. SCS represents a new perspective in challenging neurosurgical clinical fields such as cerebral ischemia and vasospasm, and seems promising as a new trend of functional neurosurgery in cerebrovascular diseases.
Monocyte- and Endothelial-Derived Microparticles Induce an Inflammatory Phenotype in Human Podocytes
Authors: Eyre Jeanette , Burton James O. , Saleem Moin A. , Mathieson Peter W. , Topham Peter S. , Brunskill Nigel J.
Published: August 2011

Background/Aims: Proteinuria is associated with cardiovascular and chronic kidney disease. Microparticles (MPs) are bioactive vesicles shed from activated cells and also linked to cardiovascular disease. MP-like structures have been identified in the glomerular basement membrane, urinary space and between the glomerular basement membrane and the podocyte. We hypothesised that circulating MPs may provide a link between vascular injury and kidney diseases by inducing podocyte phenotypic alterations, thus propagating glomerular dysfunction and proteinuria. Methods:Human umbilical vein endothelial cells and U937 monocytes were stimulated with TNF-α to produce MPs. These MPs were confirmed by electron microscopy, and added to differentiated podocyte monolayers to determine effects on podocyte albumin endocytosis and the production of soluble mediators. Results:Monocyte and endothelial MPs upregulated podocyte production of pro-inflammatory mediators monocyte chemoattractant protein-1 (p < 0.001) and interleukin-6 (p < 0.001). Only monocyte MPs upregulated podocyte secretion of VEGF (p < 0.001), known to regulate glomerular permeability. Endothelial MPs decreased podocyte albumin endocytosis by 13% compared to control cells (p < 0.01). Conclusion:MPs alter endocytic functions of podocytes and induce secretion of pro-inflammatory cytokines, potentially leading to glomerular inflammation in vivo and the development of proteinuria. This study identifies a potential pathophysiological role for circulating MPs in the kidney through effects on the podocyte.
Differential Effects of Oral Doxercalciferol (Hectorol®) or Paricalcitol (Zemplar®) in the Cyp27b1-Null Mouse Model of Uremia
Authors: St-Arnaud René , Arabian Alice , Akhouayri Omar , Knutson Joyce C. , Strugnell Stephen A.
Published: August 2011

Background/Aims: Kidney disease patients experience declining calcitriol levels and develop secondary hyperparathyroidism (SHPT). Animal models of uremia based on 5/6 nephrectomy (NTX) do not consistently reproduce this calcitriol deficiency. We developed an animal model, the NTX Cyp27b1-null mouse, which completely lacks endogenous calcitriol, and examined the suitability of this model for evaluation of treatment with vitamin D analogs in uremia. Methods: NTX was performed at 2 months of age. One week post-NTX, animals were treated for 4 weeks with vehicle; doxercalciferol at 30, 100 or 300 pg/g body weight (b.w.); or paricalcitol at 100, 300 or 1,000 pg/g b.w. by gavage 3 times per week. Results: Serum blood urea nitrogen and creatinine were elevated. Vehicle-treated NTX null mice had hypocalcemia and SHPT. Doxercalciferol at 100 or 300 pg/g b.w. normalized serum calcium and parathyroid hormone (PTH) levels. Paricalcitol at 300 or 1,000 pg/g normalized serum calcium, but PTH levels remained elevated. Osteomalacia was corrected by 100 pg/g b.w. of doxercalciferol or 1,000 pg/g b.w. of paricalcitol. The highest dose of doxercalciferol, but not of paricalcitol, significantly reduced osteitis fibrosa. Conclusion: Our results reveal the differential efficacy of doxercalciferol and paricalcitol in this novel animal model incorporating both calcitriol deficiency and renal insufficiency.
Usefulness of Red Cell Distribution Width in Predicting All-Cause Long-Term Mortality after Non-ST-Elevation Myocardial Infarction
Authors: Azab Basem , Torbey Estelle , Hatoum Hassan , Singh Jasvinder , Khoueiry Georges , Bachir Rana , McGinn, Jr. Joseph T. , McCord Donald , Lafferty James
Published: August 2011

Background: Red blood cell distribution width (RDW) is a strong predictor of adverse outcomes in patients with heart failure, stable coronary artery disease, stroke and acute myocardial infarction. The aim of our study was to explore the predictive value of RDW on all-cause mortality in patients with non-ST-segment elevation myocardial infarction (NSTEMI). Method: This observational study includes 619 NSTEMI patients, discharged from Staten Island University Hospital between September 2004 and December 2006. Patients were divided into equal RDW tertiles and survival was evaluated in each tertile. Result: Patients in the highest RDW tertile (RDW >14) had higher in-patient (7 vs. 1%) and 4-year (30 vs. 7%) mortality rates compared to those in the lowest tertile (RDW <13) (Wilcoxon χ2 = 34.64, p < 0.0001). After controlling for Global Registry of Acute Coronary Events risk profile scores and other confounding variables, the RDW adjusted hazard ratio for 4-year all-cause mortality increased by 1.10 for each one unit increase in RDW (confidence interval 1.004–1.213, p = 0.042). Conclusion: RDW is an independent predictor of all-cause long-term mortality in NSTEMI patients. Further studies are needed to clarify the mechanisms of this association between RDW and adverse outcomes in patients with coronary artery disease.
The Regulation of Valvular and Vascular Sclerosis by Osteogenic Morphogens
Authors: Boström Kristina I. , Rajamannan Nalini M. , Towler Dwight A.
Published: August 2011

Vascular calcification increasingly afflicts our aging, dysmetabolic population. Once considered only a passive process of dead and dying cells, vascular calcification has now emerged as a highly regulated form of biomineralization organized by collagenous and elastin extracellular matrices. During skeletal bone formation, paracrine epithelial-mesenchymal and endothelial-mesenchymal interactions control osteochondrocytic differentiation of multipotent mesenchymal progenitor cells. These paracrine osteogenic signals, mediated by potent morphogens of the bone morphogenetic protein and wingless-type MMTV integration site family member (Wnt) superfamilies, are also active in the programming of arterial osteoprogenitor cells during vascular and valve calcification. Inflammatory cytokines, reactive oxygen species, and oxylipids—increased in the clinical settings of atherosclerosis, diabetes, and uremia that promote arteriosclerotic calcification—elicit the ectopic vascular activation of osteogenic morphogens. Specific extracellular and intracellular inhibitors of bone morphogenetic protein–Wnt signaling have been identified as contributing to the regulation of osteogenic mineralization during development and disease. These inhibitory pathways and their regulators afford the development of novel therapeutic strategies to prevent and treat valve and vascular sclerosis.
Deer Hunting and Preserving the Commons in Dutch Colonial Taiwan
Authors: Koo Hui-wen
Published: August 2011

The Dutch East India Company exported many deerskins to Japan from its base of operations in Taiwan during the mid-seventeenth century. The accepted wisdom is that this commercial activity led to the extinction of Taiwan's deer population. Analysis of the Company's export data, however, reveals that its system of regulated hunting included a form of wildlife conservation based on self-interest.
Injecting Risk Into Prison Sentences
Authors: Bonnycastle Kevin Denys , Villebrun Charles
Published: August 2011

This article draws on penal epidemiological studies to analyze data from a prisoner-driven survey measuring HCV/HIV seroprevalence and risk behaviors in one Canadian male prison. Our data illuminate confounding points of potential blood exchange among injectors and noninjectors, HCV/HIV carriers and noncarriers, tested and untested prisoners, and prison and free community members. The survey finds higher HCV/HIV incidence and testing rates among injectors, and a penal population educated about high-risk practices. This study includes the first point-in-time estimate by penal injectors on the number and condition of needles/syringes, identifying an overlooked HCV conduit: the transfer of abandoned syringe components to new(er) syringes.
Knowledge in Cities
Authors: Gabe Todd , Abel Jaison , Ross Adrienne , Stolarick Kevin
Published: August 2011

This study identifies clusters of US and Canadian metropolitan areas with similar knowledge traits. These groups—ranging from ‘Making regions’, characterised by knowledge about manufacturing, to ‘Thinking regions’, noted for knowledge about the arts, humanities, IT and commerce—can be used by analysts and policy-makers for the purposes of regional benchmarking or comparing the types of programme and infrastructure available to support closely related economic activities. In addition, these knowledge-based clusters help to explain the types of region that have levels of economic development that exceed, or fall short of, other places with similar amounts of college attainment. Regression results show that ‘Engineering’, ‘Building’, ‘Enterprising’ and ‘Making’ regions are associated with higher levels of productivity and/or income per capita; while ‘Teaching’, ‘Understanding’, ‘Working’ and ‘Comforting’ regions have lower levels of economic development.
Effects of different extracellular matrices and growth factor immobilization on biodegradability and biocompatibility of macroporous bacterial cellulose
Authors: Lin Yung-Kai , Chen Ko-Hua , Ou Keng-Liang , Min Liu
Published: August 2011

To improve the biocompatibility of bacterial cellulose hydrogel (BCHG), different extracellular matrices (ECMs; collagen, elastin, and hyaluronan) and growth factors (B-FGF, H-EGF, and KGF) were immobilized onto macroporous BCHG. The microstructure of BCHG had inter-connective channels that were well-integrated with the alginate gel. The alginate gel formed a semi-penetrate hydrogel that allowed the ECM and growth factor to diffuse under physiological conditions. The H-EGF and collagen-modified BCHG supported the growth of human skin fibroblast. The improved BCHG was biocompatible and exhibited desirable skin substitute characteristics that could be used as a deliver vehicle for therapeutic compounds during wound healing.
Testing for seasonality using circular distributions based on non-negative trigonometric sums as alternative hypotheses
Authors: Fernández-Durán J J , Gregorio-Domínguez M M
Published: August 2011

In medical and epidemiological studies, the importance of detecting seasonal patterns in the occurrence of diseases makes testing for seasonality highly relevant. There are different parametric and non-parametric tests for seasonality. One of the most widely used parametric tests in the medical literature is the Edwards test. The Edwards test considers a parametric alternative that is a sinusoidal curve with one peak and one trough. The Cave and Freedman test is an extension of the Edwards test that is also frequently applied and considers a sinusoidal curve with two peaks and two troughs as the alternative hypothesis. The Kuiper, Hewitt and David and Newell are common non-parametric tests. Fernández-Durán (2004) developed a family of univariate circular distributions based on non-negative trigonometric (Fourier) sums (series) (NNTS) that can account for an arbitrary number of peaks and troughs. In this article, this family of distributions is used to construct a likelihood ratio test for seasonality considering parametric alternative hypotheses that are NNTS distributions.
A Two-Level Approach for the Optimal Design of Morphing Wings Based On Compliant Structures
Authors: De Gaspari Alessandro , Ricci Sergio
Published: August 2011

The great interest in developing morphing airfoils is mainly based on their capability to adapt their shape to optimize some specific aircraft performance indices during the mission. Nevertheless, the design of these kinds of devices requires the availability of ad hoc-developed procedures able to tackle the conflicting requirements such as the high deformability requested to change the airfoil shape coupled to the load-carrying capability and to the low weight.

The article proposes an approach for optimal airfoil-morphing design based on a compactapproach to describe the airfoil geometry coupled to a two-level optimization procedure. In the first one, the best deformed airfoil configuration is determined as the most efficient aerodynamic shape which at the same time limits the requested energy to deform the airfoil skin. In the second optimization level, the best internal structural configuration is obtained using an ad hoc-developed topology optimization tool based on genetic algorithms that synthesize a compliant structure able to adapt itself in order to match the optimal shape coming out from the first level. The procedure has been applied to design the morphing leading and trailing edges for an NACA 63_2215 airfoil.
Novel Sensor Placement for Damage Identification in a Cracked Complex Structure with Structural Variability
Authors: Hong Sung-Kwon , Epureanu Bogdan I. , Castanier Matthew P.
Published: August 2011

The focus of this study is on sensor placement for damage detection. In particular, novel sensor placement techniques are presented to detect the length of a crack in ground vehicles. These techniques are designed to provide vibration characteristics for structures that have both cracks and structural variability. Such techniques are needed because structural variability affects the mode shapes of a structure, and thus the optimal sensor locations for detecting cracks are affected. Two key approaches are developed and used: (1) PROMs, and (2) BMA. Based on PROMs and BMA, a novel sensor placement is proposed to determine the optimal sensor locations for complex structures with cracks and structural variability. The information from the sensors can be used to determine variations in the mode shapes of the structure for different crack lengths. The variation in mode shapes can then be used to identify the crack length. Numerical results are presented for a ground vehicle frame. The sensor placement method is applied first to find the optimal sensor locations in the presence of parameter variability, and then to identify the length of a crack.
A decentralized response-dependent MR damper for controlling building structures excited by seismic load
Authors: Lee Sang-Hyun , Youn Kyung-Jo , Min Kyung-Won
Published: August 2011

In this study, a decentralized algorithm for operating a semiactive MR damper was presented. The frictional force of the MR damper was determined based on the assumed shape functions using the displacement and velocity of the damper piston itself. The seismic response control performance of the MR damper was numerically and experimentally evaluated and compared to that of the passively or semiactively operated MR damper. The results from numerical analysis of SDOF system indicated that passively operated MR damper to have an optimal frictional force less than about 30% of the base shear force provided the smallest displacement response spectrum over all the periods. The proposed MR damper showed the better performance in reducing the absolute acceleration with the larger frictional force than the passive one. Also, the results from a three-storey benchmark building indicated that the proposed decentralized MR damper provided control performance equivalent to or better than the performance shown by the semiactive MR damper using a centralized LQR algorithm. Finally, the effectiveness of the proposed MR damper was verified through experimental tests of a full-scale five-storey steel structure with the MR dampers.
Novel Strain Energy Based Coupled Elastoplastic Damage and Healing Models for Geomaterials – Part I: Formulations
Authors: Ju J. W. , Yuan K. Y. , Kuo A. W.
Published: August 2011

Innovative strain energy based coupled elastoplastic hybrid isotropic and anisotropic damage and healing formulations for geomaterials are developed and implemented for numerical 2D earth-moving processes and cyclic loading simulations. A class of elastoplastic constitutive damage-healing models, based on a continuum thermodynamic framework, is proposed within an initial elastic strain energy based formulation. In particular, the governing incremental damage and healing evolutions are coupled and characterized through the effective stress concept in conjunction with the hypothesis of strain equivalence. The plastic flow is introduced by means of an additive split of the stress tensor. In this innovative formulation, we introduce two characteristic energy norms of the tensile and compressive strain tensors, respectively, for the damage and healing mechanisms. By incorporating a micromechanics-motivated brittle (tensile) damage characterization (P+) and a ductile (mixed tension–compression) damage-healing characterization ([Formula: see text]), the proposed hybrid isotropic and anisotropic models for soils are derived. Completely new computational algorithms are systematically developed in Part II of this sequel, based on the two-step operator splitting methodology. The elastic damage-healing predictor and the effective plastic return mapping corrector are implemented within the reproducing kernel particle method meshfree codes.
Novel Strain Energy Based Coupled Elastoplastic Damage and Healing Models for Geomaterials – Part II: Computational Aspects
Authors: Ju J. W. , Yuan K. Y. , Kuo A. W. , Chen J. S.
Published: August 2011

In Part I of this sequel (Ju, J.W., Yuan, K.Y. and Kuo, A.W. (2010). Novel Strain Energy Based Coupled Elastoplastic Damage and Healing Models for Geomaterials – Part I: Formulations, International Journal of Damage Mechanics, DOI: 10.1177/1056789511407359), we have developed innovative strain energy based coupled elastoplastic hybrid isotropic and anisotropic damage-healing formulations for geomaterials under complex 2D earth-moving processes. Emanating from a micromechanics-based brittle (tensile) damage characterization (P+) and a ductile (mixed tension–compression) damage-healing characterization ([Formula: see text]), the proposed hybrid isotropic and anisotropic damage-healing models for soils are implemented. Entirely new computational algorithms are systematically developed based on the two-step operator splitting methodology. The elastic damage-healing predictor and the plastic corrector are consistently implemented within the existing Nonlinear Meshfree Analysis Program at University of California, Los Angeles ( Chen, J.S., Wu, C.T., Yoon, S. and You, Y. (2001) . A Stabilized Conforming Nodal Integration for Galerkin Meshfree Methods, International Journal for Numerical Methods in Engineering, 50: 435–466). Several numerical simulations featuring sophisticated earth excavation, transport, compaction, and a numerical notched soil bar under cyclic tension–compression loading are presented to illustrate the salient elastoplastic damage and healing features of soils, such as shear band and partial recovery of soil stiffness due to compression (compaction) by the proposed innovative damage-healing models and step-by-step computational algorithms.
Nonlinear Analysis of RC Structures Using Isotropic Damage Model
Authors: Gopinath Smitha , Rajasankar J. , Iyer N. R.
Published: August 2011

This article proposes a simple isotropic damage model within damage mechanics framework to represent the behavior of concrete in tension. Macroscopic evolution of tensile crack is considered as damage and is mathematically defined using an exponential function of tensile strain. A damage evolution law is formulated by applying strain equivalence principle to hyperbolic tension-softening curve. Value of damage variable is assumed theoretically to vary between ‘0’ and ‘1’ to denote uncracked and ruptured states, respectively. A smeared rotating crack model is coupled with damage formulation to simulate crack propagation effects in nonlinear finite element analysis of reinforced concrete (RC) structures. Many deficiencies of smeared crack model such as stress locking, mesh-induced directional bias, and instability in response computation for near-ultimate load are overcome using the coupled model. To verify the proposed model, nonlinear static response behavior of a RC beam is computed and compared with experimental and analytical results reported in literature. Effectiveness and applicability of the model to analyze practical structures are proved by analyzing a RC chimney. Nonlinear response of RC chimney is reviewed at global level while damage states of finite elements are studied at local level.
Practitioners’ Conceptions of Academic Talent and Giftedness: Essential Factors in Deciding Classroom and School Composition
Authors: Schroth Stephen T. , Helfer Jason A.
Published: August 2011

Experts have developed varying, and sometimes conflicting, conceptions of academic talent and giftedness. Classroom and school composition often are tied to these conceptions of academic talent and giftedness, and magnet and charter schools select certain students who best “fit” their particular conception of giftedness. Educators’ perceptions and attitudes regarding academic talent and giftedness thus impact what services are delivered to which students. Little is known about educators’ beliefs regarding conceptions of academic talent and giftedness. The current national study surveyed 900 public school educators, including regular classroom teachers, administrators, and gifted education specialists, regarding their definitions of academic talent and giftedness. The educators believed that all traditional and popular conceptions of academic talent and giftedness were valid, but they were less likely to support definitions involving talents in less-traditional areas. Educators accepted some of the more recently conceived, and more inclusive, conceptions of academic talent or giftedness. Such results are potentially valuable to school administrators, gifted education specialists, and regular classroom teachers who work with academically talented and gifted students, as well as to those who are concerned with the factors influencing school or classroom composition.
Beyond Grades in Online Learning: Adaptive Profiles of Academic Self-Regulation Among Naval Academy Undergraduates
Authors: Artino Anthony R. , Stephens Jason M.
Published: August 2011

Educational psychologists have long known that students who are motivated to learn tend to experience greater academic success than their unmotivated counterparts. Using a social cognitive view of self-regulated learning as a theoretical framework, this study explored how motivational beliefs and negative achievement emotions are differentially configured among students in a self-paced online course. Additionally, this study examined how these different motivation-emotion configurations relate to various measures of academic success. Naval Academy undergraduates completed a survey that assessed their motivational beliefs (self-efficacy and task value); negative achievement emotions (boredom and frustration); and a collection of outcomes that included their use of self-regulated learning strategies (elaboration and metacognition), course satisfaction, continuing motivation, and final course grade. Students differed vastly in their configurations of course-related motivations and emotions. Moreover, students with more adaptive profiles (i.e., high motivational beliefs/low negative achievement emotions) exhibited higher mean scores on all five outcomes than their less-adaptive counterparts. Taken together, these findings suggest that online educators and instructional designers should take steps to account for motivational and emotional differences among students and attempt to create curricula and adopt instructional practices that promote self-efficacy and task value beliefs and mitigate feelings of boredom and frustration.