bluuebunny/crossref_metadata_2025 huggingface dataset:
Linear and Non-Linear Wave Models Based on Hamilton’s Principle and Stream-Function Theory: CMSE and IGN
Authors: Kim J. W. , Ertekin R. C. , Bai K. J.
Published: May 2009

Recently, two wave models based on the stream-function theory have been derived from Hamilton’s principle for gravity waves. One is the Irrotational Green-Naghdi (IGN) equation and the other is the Complementary Mild-Slope Equation (CMSE). The IGN equation has been derived to describe refraction and diffraction of nonlinear gravity waves in the time domain and in water of finite but arbitrary bathymetry. The CMSE has been derived to consider the same problem in the (linear) frequency domain. In this paper, we first describe the discuss the two models from the viewpoint of Hamilton’s principle. Then the two models are applied to a resonant scattering of Stokes waves over periodic undulations, or the Bragg scattering problem. The numerical results are compared with existing numerical predictions and experimental data. It is found here that Level 3 IGN equation can describe Bragg scattering well for arbitrary bathymetry.
Barge-Assisted Draft Reduction of Semi-Submersible Drilling Unit GSF Development Driller I for Tow-Out From Ingleside to Offshore Gulf of Mexico
Authors: van Hoorn Frank , Weaver Warren , Brekke James N. , Devoy S. Douglas
Published: May 2009

Because of its DP thrusters, the free-floating draft of the semi-submersible drilling rig GSF Development Driller I was too deep for a safe tow-out from Ingleside, TX, to open waters. In order to reduce the semi’s draft, a large cargo barge was used to lift the rig 1.0 m (3.3 ft) and thus create a reasonable ground clearance. The barge was selected, based on dimension, ballast capability, deck strength, price, and availability. Eight support brackets were welded to the barge sides and strong diaphragms welded inside the four rig braces. Detailed time domain motion analyses were performed to study the behavior of the combined units during the tow and barge removal operation offshore. In April of 2006, during a favorable weather window, the combined units were successfully towed through the channels and once in deeper waters, the barge was ballasted down and pulled out from under the rig.
Probability Distributions of Vertical Bending Moments on a FPSO in Abnormal Wave Seastates
Authors: Fonseca Nuno , Pascoal Ricardo , Guedes Soares Carlos
Published: May 2009

A method to calculate the responses of a FPSO in deterministic wave traces with abnormal waves, has been applied to calculate the motions and global structural loads induced by a large set of abnormal waves that were measured in different places. The present paper is focused on the probability distributions of the motions and global structural loads induced by the seastates which included the abovementioned abnormal waves. The objective is to compare the distributions of the wave elevation with the abnormal wave crest and trough, and to compare the distributions of the platform responses with the responses induced by the abnormal waves. In this way it is possible to conclude if the abnormal waves induce abnormal responses of the platform, or if on the other hand there are wave groups with waves smaller than the abnormal wave that induce larger responses.
Dynamic Response of Marine Structures
Authors: Kaminski Miroslaw Lech , Halkyard John
Published: May 2009

The paper presents conclusions, recommendations and offshore relevant elements of the report of the Committee II.2 -Dynamic Response as presented and discussed by the authors at the 16th International Ship and Offshore Structures Congress (ISSC 2006) in Southampton, UK, 20–25 August 2006. This includes wave-induced response, fluid impacts, noise and vibrations, explosion and shock, damping, structural monitoring, countermeasures, uncertainties, random response and a benchmark study.
Optimal Layout of Gill Cells for Very Large Floating Structures
Authors: Wang C. M. , Yao Z. J. , Hee A. M. , Tan W. L.
Published: May 2009

This paper is concerned with the optimal layout of gill cells for minimizing the differential deflection of a very large floating structure under a non-uniform load distribution over the surface of the structure. Gill cells are compartments in the floating structure where the bottom surface is perforated to allow water to flow freely in and out. At the locations of these gill cells, the buoyancy forces are eliminated. When placed appropriately, these gill cells are very cost effective in minimizing the differential deflection of the loaded structure. So the optimal layout of the gill cells is a very important design consideration. In this paper, the modeling of a very large floating structure with gill cells is developed and a computational method based on genetic algorithms for seeking the locations of a given number of gill cells is presented. The model and optimization technique are demonstrated on a floating structure which carries a heavy load in its central portion of the structure. Resulting from the non-uniform heavy load on the structure, the differential deflection may cause operational problems for equipments which are sensitive to tilting. Using gill cells that are positioned optimally, it will be shown that the differential deflection can be considerably minimized.
Recent Advances on Quasi-Static Response of Ship and Offshore Structures
Authors: Aksu Seref , Buannic Natacha , Hinrichsen Broder , Kamsvag Frode , Tanaka Yoshiteru , Tonelli Angelo , Vink J. H. , Yang Joe Ming , Yang Ping
Published: May 2009

This paper presents a summary of the recent advances on Quasi-static response of ship and offshore structures as discussed by the Technical Committee II.1 - Quasi-Static Response of International Ship and Offshore Structures Congress (ISSC), 2006. The technical committee’s mandate was concern for the quasi-static response of ship and offshore structures, as required for safety and serviceability assessments. Attention was given to uncertainty of calculation models for use in reliability methods, and both exact and approximate methods for the determination of stresses appropriate for different acceptance criteria were considered.
Loads on Ships and Offshore Structures
Authors: Temarel P.
Published: May 2009

The Loads Committee of the International Ship and Offshore Structures Congress (ISSC) critically reviews the state of the art of environmental and operational loads. Amongst these, elements more relevant to the offshore industry will be presented in this paper. These comprise wave-induced loads, including linear and nonlinear methods, multi-body interactions, slamming, green water, sloshing and rogue waves, cables and risers, vortex-induced vibrations, ice loads, fatigue loading and, verification and validation.
Recent Advances in Floating Production Systems and Their Seabed Connections
Authors: Brown David T.
Published: May 2009

This paper presents a summary of the recent advances in Floating Production Systems and associated seabed connections (moorings, risers, umbilicals, tethers etc) as discussed by the Specialist Technical Committee V.2 Floating Production Systems for the International Ship and Offshore Structures Congress (ISSC), 2006. The Technical Committee’s mandate was ‘concern for the design of floating production systems. Specific emphasis shall be given to FPSO hulls and the recent industry experience that influences the design methodology. Consideration shall be given to identification and quantification of uncertainties for use in reliability methods’.
A Radio Pulsar/X-ray Binary Link
Authors: Archibald Anne M. , Stairs Ingrid H. , Ransom Scott M. , Kaspi Victoria M. , Kondratiev Vladislav I. , Lorimer Duncan R. , McLaughlin Maura A. , Boyles Jason , Hessels Jason W. T. , Lynch Ryan , van Leeuwen Joeri , Roberts Mallory S. E. , Jenet Frederick , Champion David J. , Rosen Rachel , Barlow Brad N. , Dunlap Bart H. , Remillard Ronald A.
Published: May 2009

From X-ray Binary to Pulsar

Pulsars with millisecond rotational periods are thought to originate from neutron stars in low-mass x-ray binaries that had their spin frequencies increased by long-lasting mass transfer from their companion stars. Using data from a radio pulsar survey,

Archibald
et al.

(p.
1411
, published online 21 May; see the Perspective by

Kramer

) found a neutron star in a low-mass X-ray binary that is in the process of turning into a radio millisecond pulsar. The system, which consists of a solar-like star and a 1.69-millisecond radio pulsar, has gone through a recent accretion phase, characteristic of low-mass X-ray binaries, but it shows no accretion disk anymore, confirming the evolutionary connection between millisecond radio pulsars and low-mass X-ray binaries.
MicroRNA-92a Controls Angiogenesis and Functional Recovery of Ischemic Tissues in Mice
Authors: Bonauer Angelika , Carmona Guillaume , Iwasaki Masayoshi , Mione Marina , Koyanagi Masamichi , Fischer Ariane , Burchfield Jana , Fox Henrik , Doebele Carmen , Ohtani Kisho , Chavakis Emmanouil , Potente Michael , Tjwa Marc , Urbich Carmen , Zeiher Andreas M. , Dimmeler Stefanie
Published: May 2009

Of Life, Limb, and a Small RNA

Gene expression in mammals is controlled not only by proteins but by small noncoding RNAs called microRNAs. The involvement of these RNAs provides powerful clues about the molecular origins of human diseases and how they might be treated. Ischemic diseases arise from an inadequate blood supply.

Bonauer
et al.

(p.
1710
, published online 21 May) find that a specific microRNA that is expressed in the cells lining blood vessels (called miR-92a) functions to repress the growth of new blood vessels. MiR-92a probably acts through effects on expression of integrins, proteins involved in cell adhesion and migration. In mouse models in which an inadequate blood supply had caused damage either to heart or limb muscle, therapeutic inhibition of miR-92a led to an increase in blood vessel density in the damaged tissues and enhanced functional recovery.
Intergenerational social class stability and mobility are associated with large absolute differences in adult participation in sport and exercise
Authors: Popham Frank
Published: May 2009

Objective

To test whether there is an association of social class (im)mobility in childhood and adulthood with absolute rates of adult participation in sport and exercise.

Design

Secondary analysis of the 2003 Scottish Health Survey.

Participants

2770 Scottish men and women aged 35–54.

Results

The highest age- and sex-adjusted rate of sport and exercise was seen among those who were in the highest social class in both childhood and adulthood (62.8%), while those in the lowest social class at both stages had the lowest rate at 25.8%, 37% points lower. This gap was wider than if the assessment of participation had been based solely on childhood or adult social class. The upwardly mobile had a higher rate than their class of origin in childhood but a lower rate than their class of destination in adulthood. The downwardly mobile had a lower rate than their class of origin but a higher rate than their class of destination.

Conclusion

There are major absolute differences in participation in sport and exercise associated with social class (im)mobility that will be important to understand in order to improve population health and to reduce health inequalities.
Sport concussion assessment tool: baseline values for varsity collision sport athletes
Authors: Shehata N , Wiley J P , Richea S , Benson B W , Duits L , Meeuwisse W H
Published: May 2009

Objective:

To determine baseline symptom and neurocognitive norms for non-concussed and previously concussed varsity athletes using the sport concussion assessment tool (SCAT).

Study Design:

Descriptive cohort study.

Setting:

University of Calgary.

Subjects:

260 male and female university football, ice hockey and wrestling athletes over three seasons (2005–7).

Methods:

A baseline SCAT was completed during preseason medical evaluation. Subjects were grouped as follows: all participants, men, women, never concussed (NC) and previously concussed (PC).

Main Results:

The mean age of participants was 20.5 years (range 17–32). In total, 41.2% of all athletes had a total post-concussion symptom scale (PCSS) score of 0. The mean baseline PCSS scores were as follows: all participants 4.29; men 3.52; women 6.39; NC 3.75 and PC 5.25. The five most frequently reported symptoms for all athletes were fatigue/low energy (37% of subjects), drowsiness (23%), neck pain (20%), difficulty concentrating (18%) and difficulty remembering (18%). The median immediate recall score was 5/5 for all groups. Women scored a median of 5/5 on delayed recall, whereas all remaining groups scored a median of 4/5. Months in reverse order were successfully completed by 91.6% of subjects. All participants, women and PC scored a median of 6 on reverse digits, whereas men and NC scored a median of 5.

Conclusions:

The mean SCAT baseline PCSS score was approximately 5, although just under half of the athletes scored 0. Female athletes scored better on tests of neurocognitive function. PC athletes scored better than NC athletes on all neurocognitive tests except delayed five-word recall.
HAWKING RADIATION OF FERMIONS FOR THE KERR–SEN DILATON–AXION BLACK HOLE
Authors: CHEN DE-YOU , ZU XIAO-TAO
Published: May 2009

Recent research on Hawking radiations of the Rindler spacetime and spherically symmetric uncharged spacetime shows that the Hawking temperature can be obtained by fermions tunnelling method. In this paper, we extend this work to the charged rotating spacetime and review the Hawking radiation of the Kerr–Sen dilaton–axion black hole by fermions tunnelling. The Hawking temperature is recovered and is exactly the same as that obtained by other methods.
ON ANISOTROPIC DARK ENERGY
Authors: CHAN R. , DA SILVA M. F. A. , VILLAS DA ROCHA JAIME F.
Published: May 2009

Since the discovery of accelerated expansion of the universe, it was necessary to introduce a new component of matter distribution called dark energy. The standard cosmological model considers isotropy of the pressure and assumes an equation of state p = ωρ, relating the pressure p and the energy density ρ. The interval of the parameter ω defines the kind of matter of the universe, related to the fulfillment, or not, of the energy conditions of the fluid. The recent interest in this kind of fluid with anisotropic pressure, in the scenario of the gravitational collapse and star formation, imposes a careful analysis of the energy conditions and the role of the components of the pressure. Here, in this work, we show an example where the classification of dark energy for isotropic pressure fluids is used incorrectly for anisotropic fluids. The correct classification and its consequences are presented.
PARTICLE PRODUCTION IN COSMOLOGICAL SPACETIMES WITH ELECTROMAGNETIC FIELDS
Authors: MORADI SHAHPOOR
Published: May 2009

We calculate the charged scalar particle creation in the presence of gravitational and electromagnetic fields in two models of spatially flat Robertson–Walker spacetimes: de Sitter space and asymptotically radiation dominated model. We used the Bogoliubov transformation to compute the rate of production of the particles. Possibility of creation of massless charged particles is also discussed.
NON-INERTIAL EFFECTS IN REACTIONS OF ASTROPHYSICAL INTEREST
Authors: BERTULANI C. A. , HUANG J. T. , KRASTEV P. G.
Published: May 2009

We discuss the effects of non-inertial motion in reactions occurring in laboratory, stars, and elsewhere. It is demonstrated that non-inertial effects due to large accelerations during nuclear collisions might have appreciable effects nuclear and atomic transitions. We also explore the magnitude of the corrections induced by strong gravitational fields on nuclear reactions in massive, compact stars, and the neighborhood of black holes.
THE CONSTRUCTION OF A CLASS OF TRIVARIATE NONSEPARABLE COMPACTLY SUPPORTED WAVELETS
Authors: HUANG YONGDONG , YANG SHOUZHI , CHENG ZHENGXING
Published: May 2009

In this paper, under a mild condition, the construction of compactly supported [Formula: see text]-wavelets is obtained. Wavelets inherit the symmetry of the corresponding scaling function and satisfy the vanishing moment condition originating in the symbols of the scaling function. An example is also given to demonstrate the general theory.
SYMMETRIC MULTIVARIATE WAVELETS
Authors: KARAKAZ'YAN S. , SKOPINA M. , TCHOBANOU M.
Published: May 2009

For arbitrary matrix dilation M whose determinant is odd or equal to ±2, we describe all symmetric interpolatory masks generating dual compactly supported wavelet systems with vanishing moments up to arbitrary order n. For each such mask, we give explicit formulas for a dual refinable mask and for wavelet masks such that the corresponding wavelet functions are real and symmetric/antisymmetric. We proved that an interpolatory mask whose center of symmetry is different from the origin cannot generate wavelets with vanishing moments of order n > 0. For matrix dilations M with | det M| = 2, we also give an explicit method for construction of masks (non-interpolatory) m0symmetric with respect to a semi-integer point and providing vanishing moments up to arbitrary order n. It is proved that for some matrix dilations (in particular, for the quincunx matrix) such a mask does not have a dual mask. Some of the constructed masks were successfully applied for signal processes.
ON WAVELET METHODS FOR TESTING EQUALITY OF MEAN RESPONSE CURVES
Authors: GUO PENGFEI , OYET ALWELL JULIUS
Published: May 2009

In this article, we exploit the adaptive properties of wavelets to develop some procedures for testing the equality of nonlinear and nonparametric mean response curves which are assumed by an experimenter to be the underlying functions generating several groups of data with possibly hetereoscedastic errors. The essential feature of the techniques is the transformation of the problem from the domain of the input variable to the wavelet domain through an orthogonal discrete wavelet transformation or a multiresolution expansion. We shall see that this greatly simplifies the testing problem into either a wavelet thresholding problem or a linear wavelet regression problem. The size and power performances of the tests are reported and compared to some existing methods. The tests are also applied to data on dose response curves for vascular relaxation in the absence or presence of a nitric oxide inhibitor.
ANALYSIS OF CLASSIFICATION WITH A REJECT OPTION
Authors: CHEN HONG , LI LUOQING , TANG YUANYAN
Published: May 2009

In many classification problems, objects should be rejected when the confidence in their classification is too low. In this paper, we consider a new classification algorithm with a reject option. Based on the majority vote strategy and plug-in rules, we provide error analysis for this algorithm in ideal and realistic settings, respectively. In addition, some discussions of semi-supervised classification are given to demonstrate our theoretical analysis.
Terminating motor events for TLESR are influenced by the presence and distribution of refluxate
Authors: Kuribayashi Shiko , Massey Benson T. , Hafeezullah Muhammad , Perera Lilani , Hussaini Syed Q. , Tatro Linda , Darling Ronald J. , Franco Rose , Shaker Reza
Published: May 2009

Transient lower esophageal sphincter relaxation (TLESR) is frequently associated with reflux events and terminates with a primary or secondary peristaltic wave. However, it is unclear whether the presence and properties of the refluxate affect TLESR-termination events. The aims of this study were to determine the pattern of terminating esophageal motor activity after TLESR in healthy subjects and factors affecting the type of terminating motor event. Fifteen healthy subjects (7 men, age 18–56) were studied. High-resolution manometry and impedance/pH monitoring were performed simultaneously in supine position for 2 h after subjects took a 1,000-kcal meal (Awake Study). This procedure was repeated during the night under polysomnographic recording for 6–8 h after consuming a 1,000-kcal meal (Sleep Study). We categorized three types of TLESR-terminating motor events, primary peristalsis (PP), full secondary contraction (FSC), which propagated the entire esophagus, and partial secondary contractions (PSC), which started distal to the upper esophageal sphincter. Overall, 289 TLESR events were found. The percentages of TLESR events terminated by PP, FSC, and PSC were 22%, 14%, and 64%, respectively. TLESR events terminated by PP were less likely to be accompanied by reflux events. TLESR events terminated by FSC were significantly more likely to have evidence for proximal esophageal reflux and esophago-pharyngeal reflux. Findings were similar in awake and sleep states. We concluded that, in healthy recumbent subjects, the most common TLESR-termination event is a secondary contraction, rather than PP. Presence and distribution of the refluxate is a major influence on the type of terminating contraction.
Adrenergic activation of electrogenic K+secretion in guinea pig distal colonic epithelium: involvement of β1- and β2-adrenergic receptors
Authors: Zhang Jin , Halm Susan T. , Halm Dan R.
Published: May 2009

Adrenergic stimulation of electrogenic K+secretion in isolated mucosa from guinea pig distal colon required activation of two β-adrenergic receptor subtypes (β-AdrR). Addition of epinephrine (epi) or norepinephrine (norepi) to the bathing solution of mucosae in Ussing chambers increased short-circuit current ( Isc) and transepithelial conductance ( Gt), consistent with this cation secretion. A β-adrenergic classification was supported by propranolol antagonism of this secretory response and the lack of effect by the α-AdrR antagonists BE2254 (α1-AdrR) and yohimbine (α2-AdrR). Subtype-selective antagonists CGP20712A (β1-AdrR), ICI-118551 (β2-AdrR), and SR59320A (β3-AdrR) were relatively ineffective at inhibiting the epi-stimulated Iscresponse. In combination, CGP20712A and ICI-118551 inhibited the response, which supported a synergistic action by β1-AdrR and β2-AdrR. Expression of mRNA for both β1-AdrR and β2-AdrR was indicated by RT-PCR of RNA from colonic epithelial cells. Protein expression was indicated by immunoblot showing bands at molecular weights consistent with monomers and oligomers. Immunoreactivity (ir) for β1-AdrR and β2-AdrR was prominent in basolateral membranes of columnar epithelial cells in the crypts of Lieberkühn as well as intercrypt surface epithelium. Cells in the pericryptal sheath also had β1-AdrRirbut did not have discernable β2-AdrRir. The adrenergic sensitivity of K+secretion measured by Iscand Gtwas relatively low as indicated by EC50s of 41 ± 7 nM for epi and 50 ± 14 nM for norepi. Adrenergic activation of electrogenic K+secretion required the involvement of both β1-AdrR and β2-AdrR, occurring with an agonist sensitivity reduced compared with reported values for either receptor subtype.
Fat circadian biology
Authors: Gimble Jeffrey M. , Floyd Z. Elizabeth
Published: May 2009

While adipose tissue has long been recognized for its major role in metabolism, it is now appreciated as an endocrine organ. A growing body of literature has emerged that identifies circadian mechanisms as a critical regulator of adipose tissue differentiation, metabolism, and adipokine secretory function in both health and disease. This concise review focuses on recent data from murine and human models that highlights the interplay between the core circadian regulatory proteins and adipose tissue in the context of energy, fat, and glucose metabolism. It will be important to integrate circadian mechanisms and networks into future descriptions of adipose tissue physiology.
Inhibition of VEGF or TGF-β Signaling Activates Endothelium and Increases Leukocyte Rolling
Authors: Walshe Tony E. , Dole Vandana S. , Maharaj Arindel S.R. , Patten Ian S. , Wagner Denisa D. , D'Amore Patricia A.
Published: May 2009

Objective—Motivated by the central roles that vascular endothelial growth factor (VEGF) and transforming growth factor (TGF)-β play in the assembly and maintenance of the vasculature, we examined the impact of systemic VEGF or TGF-β signal inhibition on endothelial activation as detected by leukocyte-endothelial interactions.

Methods and Results—VEGF or TGF-β inhibition, accomplished using adenovirus expression of soluble Flt1 (Ad-sFlt1) or soluble endoglin (Ad-sEng), resulted in a significant increase in the number of leukocytes rolling along the mesenteric venous endothelium and a significant decrease in rolling velocity in Ad-sEng mice. Neutralization of VEGF or TGF-β resulted in endothelial surface expression of P-selectin and impaired peripheral vasodilatation. Neither inhibition of VEGF nor TGF-β was associated with platelet or leukocyte activation, as detected by the activation markers platelet P-selectin and the active integrin αIIbβIII, or by leukocyte expression of L-selectin. Soluble vascular cell adhesion molecule (VCAM)-1 and E-selectin were increased in sEng-expressing mice, indicating higher levels of these adhesion receptors.

Conclusions—VEGF or TGF-β neutralization leads to impaired endothelium-mediated vasodilatation and elevated expression of surface adhesion molecules, resulting in increased leukocyte adhesion. These results indicate an essential role for both VEGF and TGF-β in maintaining the endothelium in a nonactivated state and have implications for therapeutic approaches that neutralize VEGF or TGF-β.
Matrix Metalloproteinase-9 Is Essential for Ischemia-Induced Neovascularization by Modulating Bone Marrow–Derived Endothelial Progenitor Cells
Authors: Huang Po-Hsun , Chen Yung-Hsiang , Wang Chao-Hung , Chen Jia-Shiong , Tsai Hsiao-Ya , Lin Feng-Yen , Lo Wei-Yuh , Wu Tao-Cheng , Sata Masataka , Chen Jaw-Wen , Lin Shing-Jong
Published: May 2009

Objective—

Both matrix metalloproteinases (MMPs) and endothelial progenitor cells (EPCs) have been implicated in the process of neovascularization. Here we show that the impaired neovascularization in mice lacking MMP-9 is related to a defect in EPC functions in vasculogenesis.

Methods and Results—

Hindlimb ischemia surgery was conducted in MMP-9
−/−
mice and wild-type (MMP-9
+/+
) mice. Blood flow recovery was markedly impaired in MMP-9
−/−
mice when compared with that in wild-type mice as determined by laser Doppler imaging. Flow cytometry demonstrated that the number of EPC-like cells (Sca-1
+
/Flk-1
+
) in peripheral blood increased in wild-type mice after hindlimb ischemia surgery and exogenous vascular endothelial growth factor stimulation, but not in MMP-9
−/−
mice. Plasma levels and bone marrow concentrations of soluble Kit-ligand (sKitL) were significantly elevated in wild-type mice in response to tissue ischemia, but not in MMP-9
−/−
mice. C-kit positive bone marrow cells of MMP-9
−/−
mice have attenuated adhesion and migration than those isolated from wild-type mice. In in vitro studies, incubation with selective MMP-9 inhibitor suppressed the colony formation, migration, and tube formation capacities of EPC. Transplantation of bone marrow cells from wild-type mice restored collateral flow formation in MMP-9
−/−
mice.

Conclusions—

These findings suggest that MMP-9 deficiency impairs ischemia-induced neovascularization, and these effects may occur through a reduction in releasing the stem cell-active cytokine, and EPC mobilization, migration, and vasculogenesis functions.
JAM-C Induces Endothelial Cell Permeability Through Its Association and Regulation of β
3
Integrins
Authors: Li Xiaochun , Stankovic Milena , Lee Boris P.-L. , Aurrand-Lions Michel , Hahn Chris N. , Lu Ying , Imhof Beat A. , Vadas Mathew A. , Gamble Jennifer R.
Published: May 2009

Objectives—

The molecular mechanisms regulating vascular permeability are only now being elucidated. The junctional adhesion molecule (JAM) JAM-C has been linked to the induction of vascular permeability. We sought to understand the mechanism whereby JAM-C may disrupt junctional integrity in endothelial cells (ECs).

Methods and Results—

We show here that JAM-C alters permeability through modulation of integrin activity. JAM-C overexpression results in an increase in JAM-C at junctions and an increase in permeability. Conversely, knockdown of JAM-C by siRNA results in a reduction in permeability. JAM-C associates with αvβ3 integrin and regulates its localization and activity. JAM-C also inhibits the activation state of the β
1
integrin although it does not associate with this integrin. These changes induced on the integrins are mediated through regulation of the small GTPase, Rap1b but not Rap1a. Thrombin, a powerful inductor of vascular leak, causes localization of JAM-C into the junctions, whereas angiopoietin-1, an inhibitor of permeability, prevents JAM-C translocation.

Conclusions—

The regulation of EC junctional integrity involves the coordinated and dynamic modification of localization and activity of junctional stabilizers such as the integrin β
3
and the destabilizer, JAM-C.
Hypoxia Inducible Factor-2α Stabilization and Maxi-K
+
Channel β
1
-Subunit Gene Repression by Hypoxia in Cardiac Myocytes
Authors: Bautista Lucía , Castro María J. , López-Barneo José , Castellano Antonio
Published: May 2009

The Ca
2+
- and voltage-dependent K
+
(maxi-K) channel β
1
-subunit mRNA is particularly abundant in cardiomyocytes but its functional role is unknown. This is intriguing because functional maxi-K channels are not found in cardiomyocyte plasmalemma, although they have been suggested to be in the inner mitochondrial membrane and participate in cardioprotection. We report here that β
1
protein may interact with mitochondrial proteins and that the β
1
-subunit gene (KCNMB1) is repressed by sustained hypoxia in dispersed cardiomyocytes as well as in heart intact tissue. The effect of hypoxia is time- and dose-dependent, is mimicked by addition of reactive oxygen species, and selectively requires hypoxia inducible factor-2α (Hif-2α) stabilization. We have observed that adaptation to hypoxia exerts a protective role on cardiomyocytes subjected to ischemia and that, unexpectedly, this form of preconditioning absolutely depends on Hif-2α. Interference of the β
1
-subunit mRNA increases cardiomyocyte resistance to ischemia. Therefore, Hif-2α–mediated β
1
-subunit gene repression is a previously unknown mechanism that could participate in the gene expression program triggered by sustained hypoxia to prevent deleterious mitochondrial depolarization and ATP deficiency in cardiac cells. Our work provides new perspectives for research on cardiac preconditioning.
Racial and Ethnic Disparities in Outcomes and Appropriateness of Carotid Endarterectomy
Authors: Halm Ethan A. , Tuhrim Stanley , Wang Jason J. , Rojas Mary , Rockman Caron , Riles Thomas S. , Chassin Mark R.
Published: May 2009

Background and Purpose—

Prior work documented racial and ethnic disparities in incidence of stroke, stroke risk factors, and use of carotid endarterectomy. Less is known about disparities in outcomes and appropriateness of carotid endarterectomy or reasons for such inequalities.

Methods—

This was a population-based cohort of carotid endarterectomy performed in Medicare beneficiaries in New York. Clinical data were abstracted from medical charts to assess sociodemographics, clinical indication for carotid endarterectomy, disease severity, comorbidities, and deaths and strokes within 30 days of surgery. Appropriateness was based on validated criteria from a national expert panel. Differences in patients, providers, outcomes, and appropriateness were compared using χ
2
tests. Differences in risk-adjusted rates of death or nonfatal stroke were compared using multiple logistic regression accounting for patient, physician, and hospital-level risk factors.

Results—

Overall, 95.3% of patients undergoing carotid endarterectomy were white, 2.5% black, and 2.2% Hispanic (N=9093). Minorities had more severe neurological disease and more comorbidities and were more likely to be cared for by lower-volume surgeons and hospitals (
P
<0.0001). Rates of 30-day death/stroke were higher in Hispanics (9.5%) and blacks (6.9%) than whites (3.8%;
P
<0.0001). Multivariable analyses that adjusted for presurgical patient risk and provider characteristics found that blacks no longer had significantly worse outcomes (OR=1.37; CI, 0.78 to 2.40), although the higher risk of death/stroke in Hispanics persisted (OR=1.87; CI, 1.09 to 3.19). Minorities had higher rates of inappropriate surgery (Hispanics 17.6%, black 13.0%, white 7.9%;
P
<0.0001) largely due to higher comorbidity.

Conclusions—

Minorities had worse outcomes and higher rates of inappropriate surgery. Differences in underlying presurgical risk factors and provider characteristics explained the higher risk of complications in blacks, but not Hispanics.
CT Angiography for Intracerebral Hemorrhage Does Not Increase Risk of Acute Nephropathy
Authors: Oleinik Alexandra , Romero Javier M. , Schwab Kristin , Lev Michael H. , Jhawar Nupur , Delgado Almandoz Josser E. , Smith Eric E. , Greenberg Steven M. , Rosand Jonathan , Goldstein Joshua N.
Published: May 2009

Background and Purpose—

CT angiography (CTA) is receiving increased attention in intracerebral hemorrhage (ICH) for its role in ruling out vascular abnormalities and potentially predicting ongoing bleeding. Its use is limited by the concern for contrast induced nephropathy (CIN); however, the magnitude of this risk is not known.

Methods—

We performed a retrospective analysis of a prospectively collected cohort of consecutive patients with ICH presenting to a single tertiary care hospital from 2002 to 2007. Demographic, clinical, and radiographic data were prospectively collected for all patients. Laboratory data and clinical course over the first 48 hours were retrospectively reviewed. Acute nephropathy was defined as any rise in creatinine of >25% or >0.5 mg/dL, such that the highest creatinine value was above 1.5 mg/dL.

Results—

539 patients presented during the study period and had at least 2 creatinine measurements. 348 (65%) received a CTA. Acute nephropathy developed in 6% of patients who received a CTA and in 10% of those who did not (
P
=0.1). Risk of nephropathy was 14% in those receiving no contrast (130 patients), 5% in those receiving 1 contrast study (124 patients), and 6% in those receiving >1 contrast study (244 patients). Neither CTA nor any use of contrast predicted nephropathy in univariate or multivariate analysis.

Conclusion—

The risk of acute nephropathy after ICH was not increased by use of CTA. Studies of CIN that do not include a control group may overestimate the influence of contrast. Patients with ICH appear to have an 8% risk of developing “Hospital-Acquired Nephropathy.”
Relationship of Blood Pressure, Antihypertensive Therapy, and Outcome in Ischemic Stroke Treated With Intravenous Thrombolysis
Authors: Ahmed Niaz , Wahlgren Nils , Brainin Michael , Castillo José , Ford Gary A. , Kaste Markku , Lees Kennedy R. , Toni Danilo
Published: May 2009

Background and Purpose—

The optimal management of blood pressure (BP) in acute stroke remains unclear. For ischemic stroke treated with intravenous thrombolysis, current guidelines suggest pharmacological intervention if systolic BP exceeds 180 mm Hg. We determined retrospectively the association of BP and antihypertensive therapy with clinical outcomes after stroke thrombolysis.

Methods—

The SITS thrombolysis register prospectively recorded 11 080 treatments from 2002 to 2006. BP values were recorded at baseline, 2 hours, and 24 hours after thrombolysis. Outcomes were symptomatic (National Institutes of Health Stroke Scale score deterioration ≥4) intracerebral hemorrhage Type 2, mortality, and independence at (modified Rankin Score 0 to 2) 3 months. Patients were categorized by history of hypertension and antihypertensive therapy within 7 days after thrombolysis: Group 1, hypertensive treated with antihypertensives (n=5612); Group 2, hypertensive withholding antihypertensives (n=1573); Group 3, without history of hypertension treated with antihypertensives (n=995); and Group 4, without history of hypertension not treated with antihypertensives (n=2632). For 268 (2.4%) patients, these data were missing. Average systolic BP 2 to 24 hours after thrombolysis was categorized by 10-mm Hg intervals with 100 to 140 used as a reference.

Results—

In multivariable analysis, high systolic BP 2 to 24 hours after thrombolysis as a continuous variable was associated with worse outcome (
P
<0.001) and as a categorical variable had a linear association with symptomatic hemorrhage and a U-shaped association with mortality and independence with systolic BP 141 to 150 mm Hg associated with most favorable outcomes. OR (95% CI) from multivariable analysis showed no difference in symptomatic hemorrhage (1.09 [0.83 to 1.51];
P
=0.58) and independence (1.03 [0.93 to 1.10];
P
=0.80) but lower mortality (0.82 [0.73 to 0.92];
P
=0.0007) for Group 1 compared with Group 4. Group 2 had a higher symptomatic hemorrhage (1.86 [1.34 to 2.68];
P
=0.0004) and mortality (1.62 [1.41 to 1.85];
P
<0.0001) and lower independence (0.89 [0.80 to 0.99];
P
=0.04) compared with Group 4. Group 3 had similar results as Group 1.

Conclusions—

There is a strong association of high systolic BP after thrombolysis with poor outcome. Withholding antihypertensive therapy up to 7 days in patients with a history of hypertension was associated with worse outcome, whereas initiation of antihypertensive therapy in newly recognized moderate hypertension was associated with a favorable outcome.
Role of Interleukin-1β in Early Brain Injury After Subarachnoid Hemorrhage in Mice
Authors: Sozen Takumi , Tsuchiyama Reiko , Hasegawa Yu , Suzuki Hidenori , Jadhav Vikram , Nishizawa Shigeru , Zhang John H.
Published: May 2009

Background and Purpose—

The role of interleukin (IL)-1β remains unknown in early brain injury (EBI) after subarachnoid hemorrhage (SAH), although IL-1β has been repeatedly reported to increase in the brain and cerebrospinal fluid. The aim of this study is to examine the effects of IL-1β inactivation on EBI after SAH in mice.

Methods—

The endovascular perforation model of SAH was produced and 112 mice were assigned to sham, SAH+ vehicle, and SAH+ N-Ac-Tyr-Val-Ala-Asp-chloromethyl ketone (Ac-YVAD-CMK, 6 and 10 mg/kg) groups. Ac-YVAD-CMK, a selective inhibitor of IL-1β converting enzyme, or vehicle was administered intraperitoneally 1 hour post-SAH. EBI was assessed in terms of mortality within 24 hours, neurological scores, brain water content at 24 and 72 hours, Evans blue dye extravasation and Western blot for IL-1β, c-Jun N-Terminal kinase (JNK), matrix metalloproteinase (MMP)-9, and zonula occludens (ZO)-1 at 24 hours after SAH.

Results—

High-dose (10 mg/kg) but not low-dose (6 mg/kg) treatment group significantly improved neurological scores, mortality, brain water content, and Evans blue dye extravasation compared with the vehicle group. Although both dosages of Ac-YVAD-CMK attenuated the mature IL-1β induction, only high-dose treatment group significantly inhibited the phosphorylation of JNK, MMP-9 induction, and ZO-1 degradation.

Conclusion—

IL-1β activation may play an important role in the pathogenesis of EBI after SAH. The neurovascular protection of Ac-YVAD-CMK may be provided by the inhibition of JNK-mediated MMP-9 induction and the consequent preservation of tight junction protein ZO-1.
Evolving Self-Assembly in Autonomous Homogeneous Robots: Experiments with Two Physical Robots
Authors: Ampatzis Christos , Tuci Elio , Trianni Vito , Christensen Anders Lyhne , Dorigo Marco
Published: May 2009

This research work illustrates an approach to the design of controllers for self-assembling robots in which the self-assembly is initiated and regulated by perceptual cues that are brought forth by the physical robots through their dynamical interactions. More specifically, we present a homogeneous control system that can achieve assembly between two modules (two fully autonomous robots) of a mobile self-reconfigurable system without a priori introduced behavioral or morphological heterogeneities. The controllers are dynamic neural networks evolved in simulation that directly control all the actuators of the two robots. The neurocontrollers cause the dynamic specialization of the robots by allocating roles between them based solely on their interaction. We show that the best evolved controller proves to be successful when tested on a real hardware platform, the swarm-bot. The performance achieved is similar to the one achieved by existing modular or behavior-based approaches, also due to the effect of an emergent recovery mechanism that was neither explicitly rewarded by the fitness function, nor observed during the evolutionary simulation. Our results suggest that direct access to the orientations or intentions of the other agents is not a necessary condition for robot coordination: Our robots coordinate without direct or explicit communication, contrary to what is assumed by most research works in collective robotics. This work also contributes to strengthening the evidence that evolutionary robotics is a design methodology that can tackle real-world tasks demanding fine sensory-motor coordination.
Predictive Mesoscale Network Model of Cell Fate Decisions during C. elegans Embryogenesis
Authors: Winkler David A. , Burden Frank R. , Halley Julianne D.
Published: May 2009

The differentiation pathway of the nematode worm model organism C. elegans has been studied as a surrogate for future work on the human embryonic stem cell genetic networks. We extend earlier work on recursive networks by the introduction of a regularizer and more robust convergence algorithms, and by training the model to recapitulate experimental gene expression patterns rather than random expression patterns. We also assess the ability of the model to predict the expression profile on the next cell(s) in the lineage. The weight matrix from the model may be interpreted as a set of rules that guides the differentiation of the cells via a set of regulatory factors: internal genes or external entities. The activity of the regulatory factors shows patterns across the differentiation pathway that reflect the left- or right-hand split. Using these patterns, it may be possible to identify the actual factors responsible for the differentiation and to interpret the associated weights. The model was able to predict expression profiles of cells not used in training the model with a relatively low error rate.
Two Types of Baroclinic Life Cycles during the Southern Hemisphere Summer
Authors: Moon Woosok , Feldstein Steven B.
Published: May 2009

Baroclinic eddy life cycles of the Southern Hemisphere (SH) summer are investigated with NCEP–NCAR reanalysis data. A composite analysis is performed for the years 1980 through 2004. Individual life cycles are identified by local maxima in synoptic-scale eddy energy. Two types of baroclinic life cycles are examined, each defined by the strength of the barotropic energy conversion 2 days prior to the maximum baroclinic growth. For one life cycle, the barotropic conversion is anomalously weak before the maximum baroclinic growth; for the other, the barotropic conversion is anomalously strong. These two life cycles are referred to as the weak barotropic (WB) and strong barotropic (SB) life cycles.

The analyses for the WB life cycle find that a poleward anomalous wave activity flux is observed within the SH tropics and subtropics just before the initial growth of the synoptic-scale eddies. In contrast, the SB life cycle exhibits an equatorward anomalous wave activity flux prior to the initial wave development. For the WB life cycle, these changes in the wave activity flux are shown to induce a mean meridional circulation that weakens and broadens the midlatitude zonal mean jet and reduces the baroclinicity in the midlatitude lower troposphere. Opposite characteristics are observed for the SB life cycle. Since the eddy growth rate is found to be greater in the WB life cycle, these results suggest that the influences of the barotropic governor mechanism (a reduction in horizontal shear coinciding with more rapidly growing baroclinic eddies) and the midlatitude baroclinicity oppose each other at the beginning of the life cycle, with the former being dominant.

Both the WB and SB life cycles coincide with anomalous tropical convection. For the WB life cycle, there is a strengthening of the convection over the Maritime Continent, and for the SB life cycle there is a weakening in the convection over the same region. These results suggest that the two types of baroclinic life cycles are ultimately triggered by convection in the tropics.
Critiquing Models of Emotions
Authors: Smith Herman , Schneider Andreas
Published: May 2009

This article provides the first systematic empirical examination of four major genres of theories concerning the nature and rise of the corpus of human emotions with more than 2,000 statistical tests of five hypotheses. The distinction between evolutionary-universal and other ``secondary'' emotions is empirically uninformative for all five cultures. Next, the emotion-wheel theory of Plutchik receives no empirical support. All palette theories fail four empirical tests. More than 90 empirical tests fail to support Kemper and Turner in assuming that many secondary emotions arise through complex combinations of primary emotions due to socialization. The Johnson-Laird and Oatley hypothesis of five universal clusters of emotions is also tested and rejected. Researchers need to rethink the heuristic value of dichotomizing and lumping emotions in categories such as universal, primary, basic, secondary, tertiary, and so forth. There are clear empirical advantages to differentiating between emotions with three dimensions rather than two dimensions.
A fuzzy biclustering algorithm for social annotations
Authors: Lixin Han  , Hong Yan
Published: May 2009

In recent years, there has been considerable interest in the analysis of social annotations. Social annotations allow users to annotate web resources more easily, openly and freely than do taxonomies and ontologies. In this paper, we propose a novel algorithm for social annotations. It introduces a fuzzy biclustering algorithm to social annotations for identifying subgroups of users and of resources, and discovering the relationships between those users for social annotations. The algorithm employs a combination of pattern search and compromise programming to construct hierarchically structured biclusters. The pattern search method is used to compute a single objective optimal solution, and the compromise programming is used to trade-off between multiple objectives. The algorithm is not subject to the convexity limitations, and does not need to use the derivative information. It can automatically identify user communities and achieve high prediction accuracies.
Physician factors associated with outpatient palliative care referral
Authors: Ahluwalia SC , Fried TR
Published: May 2009

Outpatient palliative care can provide significant benefits to seriously ill patients, but several barriers to appropriate referrals remain. No study has examined the physician factors associated with referral to outpatient palliative care. To determine physician factors, with a focus on physician beliefs, associated with referral to palliative care. Cross-sectional study of 170 primary care physicians at Kaiser Permanente (KP), a large non-profit Health Maintenance Organisation (HMO), using a self-administered questionnaire. Of the 145 respondents, 100 (70%) reported referring any patients to the palliative care program in the prior year, with a median of 3 referrals (interquartile range 2, 6). Factors associated with referral included working at KP between 10 and 20 years as compared to <10 years [Odds ratio [OR] 6.29 (95% confidence interval [CI] 1.38, 28.6)] and having personal experience with palliative care [OR 2.13 (95% CI 0.95, 4.976)]. None of the beliefs scales was associated with referral. Physician characteristics other than their beliefs about palliative care played a significant role in determining referral. Palliative care programs should aim to increase their visibility in the outpatient setting to increase referrals by primary care physicians. Tools that help physicians identify seriously ill patients who could benefit from palliative care may also serve to increase appropriate referrals.