bluuebunny/crossref_metadata_2025 huggingface dataset:
Lattice Towers for Bottom-Fixed Offshore Wind Turbines in the Ultimate Limit State: Variation of Some Geometric Parameters
Authors: Long Haiyan , Moe Geir , Fischer Tim
Published: December 2011

Optimal solutions for offshore wind turbines (OWTs) are expected to vary from those of their onshore counterparts because of the harsh offshore climate, and differences in loadings, transportation, access, etc. This definitely includes the support structures required for service in the sea. Lattice towers might be a competitive solution for OWTs due to less physical impact from waves and less concern for visual impact. This paper addresses the design methodology of lattice towers for OWTs in the ultimate limit state and presents a FEM code that has been developed to implement this methodology. The structural topologies are specified in terms of tower cross-section geometry, the inclination of bracings, and the number of segments along the tower height. For each topology a series of towers is designed in which the bottom distance between the legs has been varied; the resulting tower mass is evaluated as a major parameter for the cost assessment. The study was conducted using the NREL 5-MW baseline wind turbine for an offshore site at a water depth of 35 m. The optimal design is searched for according to tower mass and fabrication complexity. The most economical tower geometry appears to have a constant inclination of bracing owing to its simplicity of fabrication and strong antitorsion capacity. Three-legged and four-legged alternatives have different advantages, the former having simpler geometry and the latter offering better torsion resistance. As a design driver for offshore steel structures, the fatigue life of the towers designed in the ultimate limit state should be assessed and the structures are consequently modified, if necessary. However, fatigue assessment is out of the scope of this paper and will be done in a later work.
High Performance Adaptive Control of Mechanical Servo System With LuGre Friction Model: Identification and Compensation
Authors: Wang Xingjian , Wang Shaoping
Published: December 2011

LuGre dynamic friction model has been widely used in servo system for friction compensation, but it increases the difficulty of controller design because its parameters are difficult to be identified and its internal state is immeasurable. This paper presents a parameter identification technique based on novel evolutionary algorithm (NEA) for LuGre friction model. In order to settle the practical digital implementation problem of LuGre model, this paper also proposes a modified dual-observer with discontinuous mapping and smooth transfer function. On the basis of the parameter identification results and the modified dual-observer, this paper designs an adaptive control algorithm with dynamic friction compensation for hydraulic servo system. The comparative experiments indicate that the proposed parameter identification technique and the adaptive control algorithm with modified dual-observer are effective with high tracking performance.
Hybrid Bishop-Hill Model for Elastic-Yield Limited Design With Non-orthorhombic Polycrystalline Metals
Authors: Takahashi Ribeka , Prasai Dikshya , Adams Brent L. , Mattson Christopher A.
Published: December 2011

A method is presented for adapting the classical Bishop-Hill model to the requirements of elastic/yield-limited design in metals of arbitrary crystallographic texture. The proposed Hybrid Bishop-Hill (HBH) model, which will be applied to ductile FCC metals, retains the “stress corners” of the polyhedral Bishop-Hill yield surface. However, it replaces the ‘maximum work criterion’ with a criterion that maximizes the projection of the applicable local corner stress state onto the macroscopic stress state. This compromise leads to a model that is much more accessible to yield-limited design problems. Demonstration of performance for the HBH model is presented for an extensive database for oxygen free electronic copper. The design problem considered is a hole-in-a-plate configuration of thin sheets loaded in uniaxial tension in arbitrary directions relative to the principal directions of material orthorhombicity. Results obtained demonstrate that HBH-based elastic/yield limited design is capable of predicting complex and highly nonintuitive behaviors, even within standard problems.
Mechanisms of Resistance to Chloramphenicol in Pseudomonas putida KT2440
Authors: Fernández Matilde , Conde Susana , de la Torre Jesús , Molina-Santiago Carlos , Ramos Juan-Luis , Duque Estrella
Published: December 2011

Pseudomonas putida
KT2440 is a chloramphenicol-resistant bacterium that is able to grow in the presence of this antibiotic at a concentration of up to 25 μg/ml. Transcriptomic analyses revealed that the expression profile of 102 genes changed in response to this concentration of chloramphenicol in the culture medium. The genes that showed altered expression include those involved in general metabolism, cellular stress response, gene regulation, efflux pump transporters, and protein biosynthesis. Analysis of a genome-wide collection of mutants showed that survival of a knockout mutant in the TtgABC resistance-nodulation-division (RND) efflux pump and mutants in the biosynthesis of pyrroloquinoline (PQQ) were compromised in the presence of chloramphenicol. The analysis also revealed that an ABC extrusion system (PP2669/PP2668/PP2667) and the AgmR regulator (PP2665) were needed for full resistance toward chloramphenicol. Transcriptional arrays revealed that AgmR controls the expression of the
pqq
genes and the operon encoding the ABC extrusion pump from the promoter upstream of open reading frame (ORF) PP2669.
Biochemical Study of the Comparative Inhibition of Hepatitis C Virus RNA Polymerase by VX-222 and Filibuvir
Authors: Yi Guanghui , Deval Jerome , Fan Baochang , Cai Hui , Soulard Charlotte , Ranjith-Kumar C. T. , Smith David B. , Blatt Lawrence , Beigelman Leonid , Kao C. Cheng
Published: December 2011

Filibuvir and VX-222 are nonnucleoside inhibitors (NNIs) that bind to the thumb II allosteric pocket of the hepatitis C virus (HCV) RNA-dependent RNA polymerase. Both compounds have shown significant promise in clinical trials and, therefore, it is relevant to better understand their mechanisms of inhibition. In our study, filibuvir and VX-222 inhibited the 1b/Con1 HCV subgenomic replicon, with 50% effective concentrations (EC
50
s) of 70 nM and 5 nM, respectively. Using several RNA templates in biochemical assays, we found that both compounds preferentially inhibited primer-dependent RNA synthesis but had either no or only modest effects on
de novo
-initiated RNA synthesis. Filibuvir and VX-222 bind to the HCV polymerase with dissociation constants of 29 and 17 nM, respectively. Three potential resistance mutations in the thumb II pocket were analyzed for effects on inhibition by the two compounds. The M423T substitution in the RNA polymerase was at least 100-fold more resistant to filibuvir in the subgenomic replicon and in the enzymatic assays. This resistance was the result of a 250-fold loss in the binding affinity (

K
d

) of the mutated enzyme to filibuvir. In contrast, the inhibitory activity of VX-222 was only modestly affected by the M423T substitution but more significantly affected by an I482L substitution.
Identification of Lead Compounds Targeting the Cathepsin B-Like Enzyme of Eimeria tenella
Authors: Schaeffer Marie , Schroeder Joerg , Heckeroth Anja R. , Noack Sandra , Gassel Michael , Mottram Jeremy C. , Selzer Paul M. , Coombs Graham H.
Published: December 2011

Cysteine peptidases have been implicated in the development and pathogenesis of
Eimeria
. We have identified a single-copy cathepsin B-like cysteine peptidase gene in the genome database of
Eimeria tenella
(
EtCatB
). Molecular modeling of the predicted protein suggested that it differs significantly from host enzymes and could be a good drug target. EtCatB was expressed and secreted as a soluble, active, glycosylated mature enzyme from
Pichia pastoris
. Biochemical characterization of the recombinant enzyme confirmed that it is cathepsin B-like. Screening of a focused library against the enzyme identified three inhibitors (a nitrile, a thiosemicarbazone, and an oxazolone) that can be used as leads for novel drug discovery against
Eimeria
. The oxazolone scaffold is a novel cysteine peptidase inhibitor; it may thus find widespread use.
Importance of Confirming Data on the
In Vivo
Efficacy of Novel Antibacterial Drug Regimens against Various Strains of Mycobacterium tuberculosis
Authors: De Groote Mary A. , Gruppo Veronica , Woolhiser Lisa K. , Orme Ian M. , Gilliland Janet C. , Lenaerts Anne J.
Published: December 2011

In preclinical testing of antituberculosis drugs, laboratory-adapted strains of
Mycobacterium tuberculosis
are usually used both for
in vitro
and
in vivo
studies. However, it is unknown whether the heterogeneity of
M. tuberculosis
stocks used by various laboratories can result in different outcomes in tests of antituberculosis drug regimens in animal infection models. In head-to-head studies, we investigated whether bactericidal efficacy results in BALB/c mice infected by inhalation with the laboratory-adapted strains H37Rv and Erdman differ from each other and from those obtained with clinical tuberculosis strains. Treatment of mice consisted of dual and triple drug combinations of isoniazid (H), rifampin (R), and pyrazinamide (Z). The results showed that not all strains gave the same
in vivo
efficacy results for the drug combinations tested. Moreover, the ranking of HRZ and RZ efficacy results was not the same for the two H37Rv strains evaluated. The magnitude of this strain difference also varied between experiments, emphasizing the risk of drawing firm conclusions for human trials based on single animal studies. The results also confirmed that the antagonism seen within the standard HRZ regimen by some investigators appears to be an
M. tuberculosis
strain-specific phenomenon. In conclusion, the specific identity of
M. tuberculosis
strain used was found to be an important variable that can change the apparent outcome of
in vivo
efficacy studies in mice. We highly recommend confirmation of efficacy results in late preclinical testing against a different
M. tuberculosis
strain than the one used in the initial mouse efficacy study, thereby increasing confidence to advance potent drug regimens to clinical trials.
Use of Recombinase-Based
In Vivo
Expression Technology To Characterize Enterococcus faecalis Gene Expression during Infection Identifies
In Vivo
-Expressed Antisense RNAs and Implicates the Protease Eep in Pathogenesis
Authors: Frank Kristi L. , Barnes Aaron M. T. , Grindle Suzanne M. , Manias Dawn A. , Schlievert Patrick M. , Dunny Gary M.
Published: December 2011

Enterococcus faecalis
is a member of the mammalian gastrointestinal microflora that has become a leading cause of nosocomial infections over the past several decades.
E. faecalis
must be able to adapt its physiology based on its surroundings in order to thrive in a mammalian host as both a commensal and a pathogen. We employed recombinase-based
in vivo
expression technology (RIVET) to identify promoters on the
E. faecalis
OG1RF chromosome that were specifically activated during the course of infection in a rabbit subdermal abscess model. The RIVET screen identified 249 putative
in vivo
-activated loci, over one-third of which are predicted to generate antisense transcripts. Three predicted antisense transcripts were detected in
in vitro
- and
in vivo
-grown cells, providing the first evidence of
in vivo
-expressed antisense RNAs in
E. faecalis
. Deletions in the
in vivo
-activated genes that encode glutamate 5-kinase (
proB
[EF0038]), the transcriptional regulator EbrA (
ebrA
[EF1809]), and the membrane metalloprotease Eep (
eep
[EF2380]) did not hinder biofilm formation in
in vitro
assays. In a rabbit model of endocarditis, the Δ
ebrA
strain was fully virulent, the Δ
proB
strain was slightly attenuated, and the Δ
eep
strain was severely attenuated. The Δ
eep
virulence defect could be complemented by the expression of the wild-type gene in
trans
. Microscopic analysis of early Δ
eep
biofilms revealed an abundance of small cellular aggregates that were not observed in wild-type biofilms. This work illustrates the use of a RIVET screen to provide information about the temporal activation of genes during infection, resulting in the identification and confirmation of a new virulence determinant in an important pathogen.
Role of CD11b/CD18 in the Process of Intoxication by the Adenylate Cyclase Toxin of Bordetella pertussis
Authors: Eby Joshua C. , Gray Mary C. , Mangan Annabelle R. , Donato Gina M. , Hewlett Erik L.
Published: December 2011

The adenylate cyclase toxin (ACT) ofBordetella pertussisdoes not require a receptor to generate intracellular cyclic AMP (cAMP) in a broad range of cell types. To intoxicate cells, ACT binds to the cell surface, translocates its catalytic domain across the cell membrane, and converts intracellular ATP to cAMP. In cells that express the integrin CD11b/CD18 (CR3), ACT is more potent than in CR3-negative cells. We find, however, that the maximum levels of cAMP accumulation inside CR3-positive and -negative cells are comparable. To better understand how CR3 affects the generation of cAMP, we used Chinese hamster ovary and K562 cells transfected to express CR3 and examined the steps in intoxication in the presence and absence of the integrin. The binding of ACT to cells is greater in CR3-expressing cells at all concentrations of ACT, and translocation of the catalytic domain is enhanced by CR3 expression, with ∼80% of ACT molecules translocating their catalytic domain in CR3-positive cells but only 25% in CR3-negative cells. Once in the cytosol, the unregulated catalytic domain converts ATP to cAMP, and at ACT concentrations >1,000 ng/ml, the intracellular ATP concentration is <5% of that in untreated cells, regardless of CR3 expression. This depletion of ATP prevents further production of cAMP, despite the CR3-mediated enhancement of binding and translocation. In addition to characterizing the effects of CR3 on the actions of ACT, these data show that ATP consumption is yet another concentration-dependent activity of ACT that must be considered when studying how ACT affects target cells.
Effect of Inflammatory Response on
In Vivo
Competition between Two Chlamydial Variants in the Guinea Pig Model of Inclusion Conjunctivitis
Authors: Rank Roger G. , Bowlin Anne K. , Tormanen Kati I. , Wang Yin , Maurelli Anthony T.
Published: December 2011

In order to study the interaction of variants in
in vivo
infection, we employed an azithromycin-resistant mutant (AZ
2
) and its wild-type parent (SP
6
) in the guinea pig model of
Chlamydia caviae
conjunctival infection. When each strain was inoculated individually into conjunctiva, both attained the same level of growth, but AZ
2
elicited less pathology. However, when equal numbers of the two strains were inoculated together into the guinea pig conjunctiva, SP
6
produced a significantly greater number of inclusion-forming units than AZ
2
, and the pathology reflected that of a SP
6
monoinfection. The goal of this study was to further characterize the dynamics of concomitant infection of these two distinct variants, with particular emphasis on the impact of the host response on the
in vivo
growth of each organism and the development of pathology. Animals infected with AZ
2
had reduced conjunctival infiltration with CD45
+
cells and neutrophils as well as a reduced interleukin-8 (IL-8) response. Gene expression of gamma interferon (IFN-γ), tumor necrosis factor alpha (TNF-α), CCL2, and CCL5 was also significantly lower in AZ
2
-infected animals. The lower inflammatory response induced by AZ
2
was associated with its decreased ability to activate NF-κB via Toll-like receptor 2 (TLR2). In general, the inflammatory response in animals infected with both variants was greater than in infection with AZ
2
alone, resulting in lower numbers of AZ
2
than those of SP
6
in the mixed infection. Our results suggest that the ability to elicit an inflammatory response is an important factor in the dynamics of mixed infection with strains that display different pathological phenotypes.
VimA-Dependent Modulation of Acetyl Coenzyme A Levels and Lipid A Biosynthesis Can Alter Virulence in Porphyromonas gingivalis
Authors: Aruni A. Wilson , Lee J. , Osbourne D. , Dou Y. , Roy F. , Muthiah A. , Boskovic D. S. , Fletcher H. M.
Published: December 2011

The
Porphyromonas gingivalis
VimA protein has multifunctional properties that can modulate several of its major virulence factors. To further characterize VimA,
P. gingivalis
FLL406 carrying an additional
vimA
gene and a
vimA
-defective mutant in a different
P. gingivalis
genetic background were evaluated. The
vimA
-defective mutant (FLL451) in the
P. gingivalis
ATCC 33277 genetic background showed a phenotype similar to that of the
vimA
-defective mutant (FLL92) in the
P. gingivalis
W83 genetic background. In contrast to the wild type, gingipain activity was increased in
P. gingivalis
FLL406, a
vimA
chimeric strain.
P. gingivalis
FLL451 had a five times higher biofilm-forming capacity than the parent strain. HeLa cells incubated with
P. gingivalis
FLL92 showed a decrease in invasion, in contrast to
P. gingivalis
FLL451 and FLL406, which showed increases of 30 and 40%, respectively. VimA mediated coenzyme A (CoA) transfer to isoleucine and reduced branched-chain amino acid metabolism. The lipid A content and associated proteins were altered in the
vimA
-defective mutants. The VimA chimera interacted with several proteins which were found to have an LXXTG motif, similar to the sorting motif of Gram-positive organisms. All the proteins had an N-terminal signal sequence with a putative sorting signal of L(P/T/S)X(T/N/D)G and two unique signatures of EXGXTX and HISXXGXG, in addition to a polar tail. Taken together, these observations further confirm the multifunctional role of VimA in modulating virulence possibly through its involvement in acetyl-CoA transfer and lipid A synthesis and possibly by protein sorting.
Distinct Compartmentalization of NF-κB Activity in Crypt and Crypt-Denuded Lamina Propria Precedes and Accompanies Hyperplasia and/or Colitis following Bacterial Infection
Authors: Chandrakesan Parthasarathy , Ahmed Ishfaq , Chinthalapally Anisha , Singh Pomila , Awasthi Shanjana , Anant Shrikant , Umar Shahid
Published: December 2011

Citrobacter rodentiuminduces transmissible murine colonic hyperplasia (TMCH) and variable degrees of inflammation and necrosis depending upon the genetic background. UtilizingC. rodentium-induced TMCH in C3H/HeNHsd inbred mice, we observed significant crypt hyperplasia on days 3 and 7 preceding active colitis. NF-κB activity in the crypt-denuded lamina propria (CLP) increased within 24 h postinfection, followed by its activation in the crypts at day 3, which peaked by day 7. Increases in interleukin-α1 (IL-1α), IL-12(p40), and macrophage inflammatory protein 1α (MIP-1α) paralleled NF-κB activation, while increases in IL-1α/β, IL-6/IL-12(p40)/granulocyte colony-stimulating factor (G-CSF)/keratinocyte-derived chemokine (KC)/monocyte chemotactic protein 1 (MCP-1), and MIP-1α followed NF-κB activation leading to significant recruitment of neutrophils to the colonic mucosa and increased colonic myeloperoxidase (MPO) activity. Phosphorylation of the crypt cellular and nuclear p65 subunit at serines 276 and 536 led to functional NF-κB activation that facilitated expression of its downstream target, CXCL-1/KC, during TMCH. Distinct compartmentalization of phosphorylated extracellular signal-regulated kinase 1 and 2 ([ERK1/2] Thr180/Tyr182) and p38 (Thr202/Tyr204) in the CLP preceded increases in the crypts. Inhibition of ERK1/2 and p38 suppressed NF-κB activity in both crypts and the CLP. Dietary administration of 6% pectin or 4% curcumin inC. rodentium-infected mice also inhibited NF-κB activity and blocked CD3, F4/80, IL-1α/β, G-CSF/MCP-1/KC, and MPO activity in the CLP while not affecting NF-κB activity in the crypts. Thus, distinct compartmentalization of NF-κB activity in the crypts and the CLP regulates crypt hyperplasia and/or colitis, and dietary intervention may be a novel strategy to modulate NF-κB-dependent protective immunity to facilitate crypt regeneration followingC. rodentium-induced pathogenesis.
Free Lipid A Isolated from Porphyromonas gingivalis Lipopolysaccharide Is Contaminated with Phosphorylated Dihydroceramide Lipids: Recovery in Diseased Dental Samples
Authors: Nichols Frank C. , Bajrami Bekim , Clark Robert B. , Housley William , Yao Xudong
Published: December 2011

Recent reports indicate that
Porphyromonas gingivalis
mediates alveolar bone loss or osteoclast modulation through engagement of Toll-like receptor 2 (TLR2), though the factors responsible for TLR2 engagement have yet to be determined. Lipopolysaccharide (LPS) and lipid A, lipoprotein, fimbriae, and phosphorylated dihydroceramides of
P. gingivalis
have been reported to activate host cell responses through engagement of TLR2. LPS and lipid A are the most controversial in this regard because conflicting evidence has been reported concerning the capacity of
P. gingivalis
LPS or lipid A to engage TLR2 versus TLR4. In the present study, we first prepared
P. gingivalis
LPS by the Tri-Reagent method and evaluated this isolate for contamination with phosphorylated dihydroceramide lipids. Next, the lipid A prepared from this LPS was evaluated for the presence of phosphorylated dihydroceramide lipids. Finally, we characterized the lipid A by the matrix-assisted laser desorption ionization mass spectrometry (MALDI-MS) and electrospray-MS methods in order to quantify recovery of lipid A in lipid extracts from diseased teeth or subgingival plaque samples. Our results demonstrate that both the LPS and lipid A derived from
P. gingivalis
are contaminated with phosphorylated dihydroceramide lipids. Furthermore, the lipid extracts derived from diseased teeth or subgingival plaque do not contain free lipid A constituents of
P. gingivalis
but contain substantial amounts of phosphorylated dihydroceramide lipids. Therefore, the free lipid A of
P. gingivalis
is not present in measurable levels at periodontal disease sites. Our results also suggest that the TLR2 activation of host tissues attributed to LPS and lipid A of
P. gingivalis
could actually be mediated by phosphorylated dihydroceramides.
Early change in thermal perception is not a driver of anticipatory exercise pacing in the heat
Authors: Barwood Martin James , Corbett Jo , White Danny , James Jason
Published: December 2011

Aim

Initial power output declines significantly during exercise in hot conditions on attaining a rapid increase in skin temperature when exercise commences. It is unclear whether this initial reduced power is mediated consciously, through thermal perceptual cues, or is a subconscious process. The authors tested the hypothesis that improved thermal perception (feeling cooler and more comfortable) in the absence of a change in thermal state (ie, similar deep-body and skin temperatures between spray conditions) would alter pacing and 40 km cycling time trial (TT) performance.

Method

Eleven trained participants (mean (SD): age 30 (8.1) years; height 1.78 (0.06) m; mass 76.0 (8.3) kg) completed three 40 km cycling TTs in standardised conditions (32°C, 50% RH) with thermal perception altered prior to exercise by application of cold-receptor-activating menthol spray (MENTHOL SPRAY), in contrast to a separate control spray (CONTROL SPRAY) and no spray control (CON). Thermal perception, perceived exertion, thermal responses and cycling TT performance were measured.

Results

MENTHOL SPRAY induced feelings of coolness and improved thermal comfort before and during exercise. Skin temperature profile at the start of exercise was similar between sprays (CON-SPRAY 33.3 (1.1)°C and MENTHOL SPRAY 33.4 (0.4)°C, but different to CON 34.5 (0.5)°C), but there was no difference in the pacing strategy adopted. There was no performance benefit using MENTHOL SPRAY; cycling TT completion time for CON is 71.58 (6.21) min, for CON-SPRAY is 70.94 (6.06) min and for MENTHOL SPRAY is 71.04 (5.47) min.

Conclusion

The hypothesis is rejected. Thermal perception is not a primary driver of early pacing during 40 km cycling TT in hot conditions in trained participants.
Risk management: FIFA's approach for protecting the health of football players
Authors: Fuller Colin W , Junge Astrid , Dvorak Jiri
Published: December 2011

Background

Sport and exercise have long-term health benefits, but there is also a risk that participants will sustain injuries and/or ill health from these activities. For this reason, international sports governing bodies have a responsibility to identify the risks that exist within their sport and to provide guidance to participants and other stakeholders on how these risks can be controlled within acceptable levels.

Purpose

To demonstrate how Fédération Internationale de Football Association (FIFA), as football's governing body, uses a risk management framework to identify, quantify, mitigate and communicate the risks of injury and ill health in football for men, women and children in all environments.

Method

All the research papers published by FIFA's Medical Assessment and Research Centre (F-MARC) during the period 1994 to 2011 were reviewed and categorised according to an established sport-related risk management framework.

Conclusions

F-MARC investigated and mitigated 17 areas of risk to footballers' health in a coherent and consistent approach through the process of risk management.
CT perfusion guided delayed recanalization with favorable outcome in pediatric stroke
Authors: Xavier Andrew , Kansara Amit , Majjhoo Aniel Q , Norris Gregory
Published: December 2011

There are no approved treatment options for acute ischemic stroke in the pediatric population. A case is presented of a 16-year-old boy with acute left-sided weakness who was transferred to our institution on the third day after onset of symptoms and after deterioration in his condition. He had right internal carotid artery occlusion beyond the origin of the ophthalmic artery. CT perfusion study showed a large area of penumbra in the right middle cerebral artery distribution. Recanalization was achieved with self-expanding stent placement and mechanical thrombectomy. Post procedure CT perfusion study showed resolution of the penumbra. At the 3 month follow-up, his modified Rankin Scale score was 1 and at 1 year it was 0. A subset of pediatric patients with acute ischemic stroke secondary to large intracranial arterial occlusion may be potential candidates for this treatment approach.
Mechanical thrombectomy as first-line treatment for venous sinus thrombosis: technical considerations and preliminary results using the AngioJet device
Authors: Dashti Shervin R , Hu Yin C , Yao Tom , Fiorella David , Mitha Alim P , Albuquerque Felipe C , McDougall Cameron G
Published: December 2011

Background

Cerebral venous sinus thrombosis (CVT) is an uncommon cause of stroke that is usually treated medically with intravenous heparin therapy followed by long-term anticoagulation therapy. A series of patients with CVT who underwent rheolytic thrombectomy with the AngioJet as a first-line adjunctive treatment in addition to standard anticoagulation therapy is presented.

Methods

Prospectively maintained endovascular databases at two institutions were retrospectively reviewed. The available clinical and imaging data were compiled at each institution and combined for analysis.

Results

Over 18 months, 13 patients (seven women and six men; age range 17–73 years, median age 45 years) with CVT were treated with rheolytic thrombectomy. Immediate (partial or complete) recanalization of the thrombosed intracranial sinuses was achieved in all patients. At a median radiographic follow-up of 7 months there was continued patency of all recanalized sinuses. Clinical follow-up was available on nine patients: modified Rankin score of 0 in four patients, 1 in three patients and 6 in two patients.

Conclusion

This series demonstrates the feasibility of performing mechanical thrombectomy as a first-line treatment for acute CVT. This technique facilitates the prompt restoration of intracranial venous outflow, which may result in rapid neurological and symptomatic improvement.
MODAL RESTRICTION SEMIGROUPS: TOWARDS AN ALGEBRA OF FUNCTIONS
Authors: JACKSON MARCEL , STOKES TIM
Published: December 2011

Restriction semigroups model algebras of partial maps under composition and domain. Here we consider restriction semigroups for which the usual Boolean operations on domains are modeled. Such algebras are capable of modeling the usual modal operators considered in dynamic logic. Indeed adding a natural functional variant of union to the signature gives a deterministic version of the modal semirings of Möller and Struth, but also a monoidal version of the classical restriction categories of Cockett and Manes. Other operations modeled are intersection and (in the finite case) functional iteration. In each case, axiomatizations of the concrete functional examples are given, leading to algebraic models of partial maps incorporating all the domain-related and set-theoretic operations previously considered. Our algebras furnish natural algebraic semantics for the logics of deterministic computer programs, leading to new results for some variants of propositional dynamic logic.
COUNTING NUMERICAL SEMIGROUPS WITH SHORT GENERATING FUNCTIONS
Authors: BLANCO VÍCTOR , GARCÍA-SÁNCHEZ PEDRO A. , PUERTO JUSTO
Published: December 2011

This paper presents a new methodology to compute the number of numerical semigroups of given genus or Frobenius number. We apply generating function tools to the bounded polyhedron that classifies the semigroups with given genus (or Frobenius number) and multiplicity. First, we give theoretical results about the polynomial-time complexity of counting these semigroups. We also illustrate the methodology analyzing the cases of multiplicity 3 and 4 where some formulas for the number of numerical semigroups for any genus and Frobenius number are obtained.
ON ITERATED MAL'CEV PRODUCTS WITH A PSEUDOVARIETY OF GROUPS
Authors: DELGADO MANUEL , STEINBERG BENJAMIN
Published: December 2011

We characterize H-solvable semigroups with respect to a pseudovariety H of groups. Applications are given to iterated Mal'cev products with H.
CONSTRAINTS ON THE HUBBLE PARAMETER FROM GALAXY CLUSTERS AND THE VALIDITY OF THE COSMIC DISTANCE DUALITY RELATION
Authors: HOLANDA R. F. L.
Published: December 2011

Constraints on the Hubble parameter, H0, via X-ray surface brightness and Sunyaev–Zel'dovich effect (SZE) observations of the galaxy clusters depend on the validity of the cosmic distance duality relation (DD relation), η = DL(z)(1+z)-2/DA(z) = 1, where DL and DA are the luminosity distance and angular diameter distance (ADD), respectively. In this work, we argue that if the DD relation does not hold, the X-ray plus SZE technique furnishes a [Formula: see text]. We use 25 ADD of galaxy clusters to obtain simultaneous constraints on H0 and possible violation of the DD relation in a flat ΛCDM model. Such a violation is parametrized by two functions: η(z) = 1 + η0z and η(z) = 1 + η0z/(1+z), where η0 is a constant parameter quantifying possible departures from the strict validity. Finally, by marginalizing on the η0 in both parametrizations, we obtain constraints on H0 regardless of the validity of the DD relation. For the linear and nonlinear η(z) functions, we obtain [Formula: see text] km/s/Mpc and [Formula: see text] km/s/Mpc, respectively (without systematic errors). Our results support recent H0 measurements by using X-ray and SZE observations of galaxy clusters which have taken the distance duality as valid.
Deflexed didymograptids from the Lower Ordovician Skiddaw Group of northern England
Authors: Rushton A. W. A.
Published: December 2011

The type species of
Corymbograptus
,
Didymograptus v-fractus
, is discussed and a neotype is proposed. The zonal graptolites
Didymograptus varicosus
and
D. deflexus
, mainly from the Loweswater Formation of the Skiddaw Group succession, are discussed and illustrated as species of
Baltograptus
. Study of their proximal structure shows that the identification of
D. varicosus
in the Loweswater Formation is not correct, and the English specimens are here assigned to
Baltograptus jacksoni
sp. nov.
Scandinavian Isograptids (Graptolithina, Isograptidae): Biostratigraphy and Taxonomy
Authors: Maletz Jörg
Published: December 2011

The Lower–Middle Ordovician of Scandinavia is largely dominated by endemic Atlantic Province graptolite faunas, which are useful only for local biostratigraphy and paleoecology, but are difficult for correlation on an inter-continental scale. Isograptids, regarded as essential for inter-continental biostratigraphic correlations in the Lower–Middle Ordovician due to their wide palaeobiogeographic distribution, have rarely been recorded from the region. The Scandinavian Tøyen Shale and Bogo Shale formations bear a number of isograptids that range in age from the late Floian to the early Darriwilian, and these provide a good tool for inter-continental correlations of this interval.
Isograptus caduceus norvegicus
Monsen and
Isograptus spinosus
Spjeldnaes are interpreted as possible tetragraptid species. The following biostratigraphically important
Isograptus
species from Scandinavia are described as new:
Isograptus spjeldnaesi
n. sp.,
Isograptus rigidus
n. sp.
Isograptus mobergi
n. sp. and Scandinavian zonal names in the Dapingian are revised accordingly.
GrapEl – a simple spreadsheet application for managing and disseminating graptolite biozonal range chart data
Authors: Howe Michael P. A.
Published: December 2011

Biostratigraphical data frequently consist of tables indicating the presence, absence or relative abundance of taxa in a sequence of rock units or time units such as biozones or various chronostratigraphic units. Spreadsheet programs provide a simple means for managing this data and can be used for archiving and disseminating it, in addition to manipulating it. A simple spreadsheet (‘GrapEl’) is used to link the biozonal ranges of graptolite taxa to illustrations of representative or type specimens. Use of the filtering function enables the rapid selection of species from particular biozones, or species belonging to particular genera, and is intended to assist workers with a limited working knowledge of the faunas concerned. This approach is briefly compared to other uses of spreadsheets and databases in the management, analysis and distribution of graptolite biostratigraphical data.

Supplementary material:
‘GrapEl’ spreadsheets are available at
http://www.geolsoc.org.uk/SUP18504
The evolutionary lineage of
Petalolithus
to
Cephalograptus
: evidence from Coalpit Bay, Northern Ireland
Authors: Snelling Andrea M. , Zalasiewicz Jan A.
Published: December 2011

The evolution of graptolites is the basis upon which much of the Lower Palaeozoic is subdivided. Amongst the clearest evolutionary lineages within graptolites are those that show seemingly unidirectional trends in morphology, such as the sequence of stratigraphically successive taxa of
Petalolithus
and
Cephalograptus
, discussed here. Graptolite specimens collected in the 1960s from Coalpit Bay, Northern Ireland are consistent with the succession established in the Czech Republic by
Bouček & Přibyl (1941)
and
Štorch (1998)
, and include the first UK records of
P
. aff
. krizi
. We recognise other intermediate forms within this lineage that may enable further subdivision of the
convolutus
Biozone.
Mining English-Chinese Named Entity Pairs from Comparable Corpora
Authors: Li Lishuang , Wang Peng , Huang Degen , Zhao Lian
Published: December 2011

Bilingual Named Entity (NE) pairs are valuable resources for many NLP applications. Since comparable corpora are more accessible, abundant and up-to-date, recent researches have concentrated on mining bilingual lexicons using comparable corpora. Leveraging comparable corpora, this research presents a novel approach to mining English-Chinese NE translations by combining multi-dimension features from various information sources for every possible NE pair, which include the transliteration model, English-Chinese matching, Chinese-English matching, translation model, length, and context vector. These features are integrated into one model with linear combination and minimum sample risk (MSR) algorithm. As for the high type-dependence of NE translation, we integrate different features according to different NE types. We experiment with the above individual feature or integrated features to mine person NE (PN) pairs, location NE (LN) pairs and organization NE (ON) pairs. When using transliteration and length to mine PN pairs, we achieve the best performance of 84.9% (
F
-score). The LN pairs can be mined with the features of transliteration model, length, translation model, English-Chinese matching and Chinese-English matching. And the best performance is 83.4% (
F
-score). The ON pairs can be mined with the features of English-Chinese matching and Chinese-English matching. It reaches the best performance with 84.1% (
F
-score).
CyberWalk
Authors: Souman J. L. , Giordano P. Robuffo , Schwaiger M. , Frissen I. , Thümmel T. , Ulbrich H. , Luca A. De , Bülthoff H. H. , Ernst M. O.
Published: December 2011

Despite many recent developments in virtual reality, an effective locomotion interface which allows for normal walking through large virtual environments was until recently still lacking. Here, we describe the new CyberWalk omnidirectional treadmill system, which makes it possible for users to walk endlessly in any direction, while never leaving the confines of the limited walking surface. The treadmill system improves on previous designs, both in its mechanical features and in the control system employed to keep users close to the center of the treadmill. As a result, users are able to start walking, vary their walking speed and direction, and stop walking as they would on a normal, stationary surface. The treadmill system was validated in two experiments, in which both the walking behavior and the performance in a basic spatial updating task were compared to that during normal overground walking. The results suggest that walking on the CyberWalk treadmill is very close to normal walking, especially after some initial familiarization. Moreover, we did not find a detrimental effect of treadmill walking in the spatial updating task. The CyberWalk system constitutes a significant step forward to bringing the real world into the laboratory or workplace.
Interactive films and coconstruction
Authors: Verdugo Renato , Nussbaum Miguel , Corro Pablo , Núñez Palma Pablo , Navarrete Paula
Published: December 2011

Interactive Filmmaking is both an aesthetic and technological challenge. Steerable plots, where audiences are not passive viewers but active participants of the narrative experience, require an engaging narrative model as well as a technologically feasible structure. This article discusses the connection between aesthetics, cinema, and interactivity and presents a model for interactive narration that is based on the audience's ability to read and interpret footage differently according to its context. Through a detour narrative model it is possible to engage audiences in a coconstructive hypermedia experience while at the same time minimizing the amount of footage required. An interface model that allows seamless hypervideo navigation through graphic interaction is also discussed, and the interactive short film
The Crime or Revenge of Fernando Moreno
is presented, along with user experience and usability studies that experimentally prove our hypothesis.
Combining Discretionary Policy with Mandatory Information Flow in Operating Systems
Authors: Mao Ziqing , Li Ninghui , Chen Hong , Jiang Xuxian
Published: December 2011

Discretionary Access Control (DAC) is the primary access control mechanism in today’s major operating systems. It is, however, vulnerable to Trojan Horse attacks and attacks exploiting buggy software. We propose to combine the discretionary policy in DAC with the dynamic information flow techniques in MAC, therefore achieving the best of both worlds, that is, the DAC’s easy-to-use discretionary policy specification and MAC’s defense against threats caused by Trojan Horses and buggy programs. We propose the Information Flow Enhanced Discretionary Access Control (IFEDAC) model that implements this design philosophy. We describe our design of IFEDAC, and discuss its relationship with the Usable Mandatory Integrity Protection (UMIP) model proposed earlier by us. In addition, we analyze their security property and their relationships with other protection systems. We also describe our implementations of IFEDAC in Linux and the evaluation results and deployment experiences of the systems.
The Frog-Boiling Attack
Authors: Chan-Tin Eric , Heorhiadi Victor , Hopper Nicholas , Kim Yongdae
Published: December 2011

A network coordinate system assigns Euclidean “virtual” coordinates to every node in a network to allow easy estimation of network latency between pairs of nodes that have never contacted each other. These systems have been implemented in a variety of applications, most notably the popular Vuze BitTorrent client. Zage and Nita-Rotaru (at CCS 2007) and independently, Kaafar et al. (at SIGCOMM 2007), demonstrated that several widely-cited network coordinate systems are prone to simple attacks, and proposed mechanisms to defeat these attacks using outlier detection to filter out adversarial inputs. Kaafar et al. goes a step further and requires that a fraction of the network is trusted. More recently, Sherr et al. (at USENIX ATC 2009) proposed Veracity, a distributed reputation system to secure network coordinate systems. We describe a new attack on network coordinate systems, Frog-Boiling, that defeats all of these defenses. Thus, even a system with trusted entities is still vulnerable to attacks. Moreover, having witnesses vouch for your coordinates as in Veracity does not prevent our attack. Finally, we demonstrate empirically that the Frog-Boiling attack is more disruptive than the previously known attacks: systems that attempt to reject “bad” inputs by statistical means or reputation cannot be used to secure a network coordinate system.
The university of Florida sparse matrix collection
Authors: Davis Timothy A. , Hu Yifan
Published: December 2011

We describe the University of Florida Sparse Matrix Collection, a large and actively growing set of sparse matrices that arise in real applications. The Collection is widely used by the numerical linear algebra community for the development and performance evaluation of sparse matrix algorithms. It allows for robust and repeatable experiments: robust because performance results with artificially generated matrices can be misleading, and repeatable because matrices are curated and made publicly available in many formats. Its matrices cover a wide spectrum of domains, include those arising from problems with underlying 2D or 3D geometry (as structural engineering, computational fluid dynamics, model reduction, electromagnetics, semiconductor devices, thermodynamics, materials, acoustics, computer graphics/vision, robotics/kinematics, and other discretizations) and those that typically do not have such geometry (optimization, circuit simulation, economic and financial modeling, theoretical and quantum chemistry, chemical process simulation, mathematics and statistics, power networks, and other networks and graphs). We provide software for accessing and managing the Collection, from MATLAB™, Mathematica™, Fortran, and C, as well as an online search capability. Graph visualization of the matrices is provided, and a new multilevel coarsening scheme is proposed to facilitate this task.
High-performance up-and-downdating via householder-like transformations
Authors: Van De Geijn Robert A. , Van Zee Field G.
Published: December 2011

We present high-performance algorithms for up-and-downdating a Cholesky factor or QR factorization. The method uses Householder-like transformations, sometimes called hyperbolic Householder transformations, that are accumulated so that most computation can be cast in terms of high-performance matrix-matrix operations. The resulting algorithms can then be used as building blocks for an algorithm-by-blocks that allows computation to be conveniently scheduled to multithreaded architectures like multicore processors. Performance is shown to be similar to that achieved by a blocked QR factorization via Householder transformations.
Algorithm 915, SuiteSparseQR
Authors: Davis Timothy A.
Published: December 2011

SuiteSparseQR is a sparse QR factorization package based on the multifrontal method. Within each frontal matrix, LAPACK and the multithreaded BLAS enable the method to obtain high performance on multicore architectures. Parallelism across different frontal matrices is handled with Intel's Threading Building Blocks library. The symbolic analysis and ordering phase pre-eliminates singletons by permuting the input matrix
A
into the form [
R
11
R
12
; 0
A
22
] where
R
11
is upper triangular with diagonal entries above a given tolerance. Next, the fill-reducing ordering, column elimination tree, and frontal matrix structures are found without requiring the formation of the pattern of
A
TA
. Approximate rank-detection is performed within each frontal matrix using Heath's method. While Heath's method is not always exact, it has the advantage of not requiring column pivoting and thus does not interfere with the fill-reducing ordering. For sufficiently large problems, the resulting sparse QR factorization obtains a substantial fraction of the theoretical peak performance of a multicore computer.
Corrigendum
Authors: Rao Anil V. , Benson David A. , Darby Christopher , Patterson Michael A. , Francolin Camila , Sanders Ilyssa , Huntington Geoffrey T.
Published: December 2011

An algorithm is described to solve multiple-phase optimal control problems using a recently developed numerical method called the
Gauss pseudospectral method
. The algorithm is well suited for use in modern vectorized programming languages such as FORTRAN 95 and MATLAB. The algorithm discretizes the cost functional and the differential-algebraic equations in each phase of the optimal control problem. The phases are then connected using linkage conditions on the state and time. A large-scale nonlinear programming problem (NLP) arises from the discretization and the significant features of the NLP are described in detail. A particular reusable MATLAB implementation of the algorithm, called
GPOPS
, is applied to three classical optimal control problems to demonstrate its utility. The algorithm described in this article will provide researchers and engineers a useful software tool and a reference when it is desired to implement the Gauss pseudospectral method in other programming languages.
Spatial role labeling
Authors: Kordjamshidi Parisa , Van Otterlo Martijn , Moens Marie-Francine
Published: December 2011

This article reports on the novel task of
spatial role labeling
in natural language text. It proposes machine learning methods to extract spatial roles and their relations. This work experiments with both a step-wise approach, where spatial prepositions are found and the related trajectors, and landmarks are then extracted, and a joint learning approach, where a spatial relation and its composing indicator, trajector, and landmark are classified collectively. Context-dependent learning techniques, such as a skip-chain conditional random field, yield good results on the GUM-evaluation (Maptask) data and CLEF-IAPR TC-12 Image Benchmark. An extensive error analysis, including feature assessment, and a cross-domain evaluation pinpoint the main bottlenecks and avenues for future research.