bluuebunny/crossref_metadata_2025 huggingface dataset:
Bubbling and jetting regimes in planar coflowing air–water sheets
Authors: BOLAÑOS-JIMÉNEZ R. , SEVILLA A. , GUTIÉRREZ-MONTES C. , SANMIGUEL-ROJAS E. , MARTÍNEZ-BAZÁN C.
Published: July 2011

The dynamics of a plane air sheet surrounded by a coflowing water film, discharging into stagnant air, is investigated by means of experiments and linear stability theory. For fixed values of the water-to-air thickness ratio,h=hw,0*/ha,0* ≃ 5.27, and of the air-to-water density ratio,S= ρa/ρw≃ 0.0012, two different flow regimes are experimentally observed depending on the values of two control parameters, namely the Weber number, defined asWe= ρwuw,0*2ha,0*/σ, and the velocity ratio, Λ =uw,0*/ua,0*, whereuw,0* andua,0* are the water velocity and the mean air velocity at the exit slit, respectively, andha,0* andhw,0* are the half-thicknesses of the air and water sheets at the exit. The study focuses on the characterization of the transition between the two regimes found experimentally: a bubbling regime, leading to the periodic breakup of the air sheet, and a jetting regime, where both sheets evolve slowly downstream without breaking. With the aim of exploring whether the transition from the jetting to the bubbling regime is related to a convective/absolute instability transition, we perform a linear spatiotemporal stability analysis. The base flow is described by a simple model that incorporates the downstream evolution of the sheets, which shows excellent agreement with our experiments if the existence of a sufficiently long region of absolute instability, of the order of one absolute wavelength evaluated at the nozzle exit, is imposed as an additional requirement. Finally, we show that the transition is also properly captured by two-dimensional numerical simulations using the volume of fluid technique.
The horizon problem for prevalent surfaces
Authors: FALCONER K. J. , FRASER J. M.
Published: July 2011

We investigate the box dimensions of the horizon of a fractal surface defined by a functionf∈C[0,1]2. In particular we show that a prevalent surface satisfies the ‘horizon property’, namely that the box dimension of the horizon is one less than that of the surface. Since a prevalent surface has box dimension 3, this does not give us any information about the horizon of surfaces of dimension strictly less than 3. To examine this situation we introduce spaces of functions with surfaces of upper box dimension at most α, for α ∈ [2,3). In this setting the behaviour of the horizon is more subtle. We construct a prevalent subset of these spaces where the lower box dimension of the horizon lies between the dimension of the surface minus one and 2. We show that in the sense of prevalence these bounds are as tight as possible if the spaces are defined purely in terms of dimension. However, if we work in Lipschitz spaces, the horizon property does indeed hold for prevalent functions. Along the way, we obtain a range of properties of box dimensions of sums of functions.
New leveling and bias estimation algorithms for processing COSMIC/FORMOSAT‐3 data for slant total electron content measurements
Authors: Stephens P. , Komjathy A. , Wilson B. , Mannucci Anthony
Published: July 2011

Ionospheric modeling can be improved by the inclusion of occultation data between satellites and GPS transmitters. COSMIC/FORMOSAT‐3 provides a large data set of such occultations. In order to utilize these absolute measurements in an assimilative model, the data must be carefully processed; the level of the ionospheric combination and the differential biases must be accurately determined. The COSMIC GPS receivers operate in a high multipath environment; a phase leveling algorithm, utilizing the information in the multipath, improves the leveling errors by at least 0.4 total electron content units. Receiver biases are then computed from the leveled data by making some simplifying assumptions about the structure of the ionosphere and plasmasphere. This processing algorithm provides occultation measurements as slant total electron content to an accuracy of 3.55 total electron content units.
New measurements of total ionizing dose in the lunar environment
Authors: Mazur J. E. , Crain W. R. , Looper M. D. , Mabry D. J. , Blake J. B. , Case A. W. , Golightly M. J. , Kasper J. C. , Spence H. E.
Published: July 2011

We report new measurements of solar minimum ionizing radiation dose at the Moon onboard the Lunar Reconnaissance Orbiter (LRO) from June 2009 through May 2010. The Cosmic Ray Telescope for the Effects of Radiation (CRaTER) instrument on LRO houses a compact and highly precise microdosimeter whose design allows measurements of dose rates below 1 micro‐Rad per second in silicon achieved with minimal resources (20 g, ∼250 milliwatts, and ∼3 bits/second). We envision the use of such a small yet accurate dosimeter in many future spaceflight applications where volume, mass, and power are highly constrained. As this was the first operation of the microdosimeter in a space environment, the goal of this study is to verify its response by using simultaneous measurements of the galactic cosmic ray ionizing environment at LRO, at L1, and with other concurrent dosimeter measurements and model predictions. The microdosimeter measured the same short timescale modulations in the galactic cosmic rays as the other independent measurements, thus verifying its response to a known source of minimum‐ionizing particles. The total dose for the LRO mission over the first 333 days was only 12.2 Rads behind ∼130 mils of aluminum because of the delayed rise of solar activity in solar cycle 24 and the corresponding lack of intense solar energetic particle events. The dose rate in a 50 km lunar orbit was about 30 percent lower than the interplanetary rate, as one would expect from lunar obstruction of the visible sky.
Validation and Quantification of [18F]Altanserin Binding in the Rat Brain Using Blood Input and Reference Tissue Modeling
Authors: Riss Patrick J , Hong Young T , Williamson David , Caprioli Daniele , Sitnikov Sergey , Ferrari Valentina , Sawiak Steve J , Baron Jean-Claude , Dalley Jeffrey W , Fryer Tim D , Aigbirhio Franklin I
Published: July 2011

The 5-hydroxytryptamine type 2a (5-HT2A) selective radiotracer [18F]altanserin has been subjected to a quantitative micro-positron emission tomography study in Lister Hooded rats. Metabolite-corrected plasma input modeling was compared with reference tissue modeling using the cerebellum as reference tissue. [18F]altanserin showed sufficient brain uptake in a distribution pattern consistent with the known distribution of 5-HT2A receptors. Full binding saturation and displacement was documented, and no significant uptake of radioactive metabolites was detected in the brain. Blood input as well as reference tissue models were equally appropriate to describe the radiotracer kinetics. [18F]altanserin is suitable for quantification of 5-HT2A receptor availability in rats.
2011 German Escherichia coli outbreak: Alignment-free whole-genome phylogeny by feature frequency profiles
Authors: Cheung Man Kit , LI Lei , Nong Wenyan , Kwan Hoi Shan
Published: July 2011

Accuracy of SNP-based whole-genome phylogeny reconstruction relies heavily on quality of sequence alignment which is particularly hindered by poorly assembled genomes. Alignment-free methods might provide additional insights. Here, we constructed a whole-genome phylogeny of 9 E.coli isolates from the 2011 German outbreak against existing E. coli genomes using the alignment-free feature frequency profile method. In addition, we looked for gene elements that distinguish the outbreak group from the other E. coli strains and possibly accounted for the emergence of the outbreak isolates using the distinguishing feature analysis.
The influence of neighbourhood socio-demographic factors on densities of free-roaming cat populations in an urban ecosystem in Israel
Authors: Finkler Hilit , Hatna Erez , Terkel Joseph
Published: July 2011

Context Free-roaming cat populations are abundant in many urban ecosystems worldwide. Their management is necessary for reasons of public health, risk of wildlife predation and cat welfare related to their high densities. Trap–neuter–return (TNR) programs are now the main cat population control strategy in urban areas. However, the efficacy of such strategies is difficult to evaluate without more precise estimates of cat numbers and a better knowledge of anthropogenic influences on cat densities. Aims We aimed to estimate free-roaming cat population numbers and density in residential neighbourhoods in Tel Aviv, and to investigate population densities in relation to several socio-demographic factors. Methods We compared free-roaming cat population densities in terms of neighbourhood socio-economic status (SES), housing type, human density and percentage of residential and commercial areas. Five consecutive cat density surveys were carried out in eight residential neighbourhoods in Israel – four in northern Tel Aviv, characterised by high SES, and four in southern Tel Aviv, characterised by low SES. The photographic capture–recapture technique was used and abundance estimates were evaluated using the MARK program. Regression analyses examined the effect of socio-demographic factors on cat densities. Key results Neighbourhood socio-economic status significantly influenced kitten density and proportion of neutered cats in the total population: southern neighbourhoods had higher kitten densities and lower neutered cat proportions compared with northern neighbourhoods. Higher adult cat densities featured in mixed profile neighbourhoods of residential and commercial areas compared with solely residential neighbourhoods. Using the linear equation from the regression analysis the entire free-roaming cat population in Tel Aviv was extrapolated to 39 000 cats. Conclusions The results suggest that adult cat and kitten densities depend in part on socio-demographic factors, specifically on neighbourhood socio-economic status and the proportion of residential area. Implications Our findings in Tel Aviv may be used to improve cat management efforts, by focusing on neighbourhoods hosting higher cat densities; as well as to improve cat welfare by focusing on neighbourhoods with lower neutering rates and higher kitten densities. Finally, the current study may serve as a basis for studies in other cities with similar cat overpopulation problems.
Ultrafast Energy Transfer in Artificial Antenna Molecule Measured by Transient Fluorescence Spectroscopy
Authors: Chen Hai-long , Weng Yu-xiang , Li Xi-you
Published: July 2011

We have reported previously the ultrafast energy transfer process with a time constant of 0.8 ps from a monomeric to a dimeric subunit within a perylenetetracarboxylic diimide trimer, which was derived indirectly from a model fitting into the transient absorption experimental data. Here we present a direct ultrafast fluorescence quenching measurement by employing fs time-resolved transient fluorescence spectroscopy based on noncollinear optical parametric amplification technique. The rapid decay of the monomer's emission due to energy transfer was observed directly with a time constant of about 0.82 ps, in good agreement with the previous result.
Suppressors of RNA Silencing Encoded by the Components of the Cotton Leaf Curl Begomovirus-BetaSatellite Complex
Authors: Amin Imran , Hussain Khadim , Akbergenov Rashid , Yadav Jitender S. , Qazi Javaria , Mansoor Shahid , Hohn Thomas , Fauquet Claude M. , Briddon Rob W.
Published: July 2011

Begomoviruses (family Geminiviridae) are single-stranded DNA viruses transmitted by the whitefly Bemisia tabaci. Many economically important diseases in crops are caused by begomoviruses, particularly in tropical and subtropical environments. These include the betasatellite-associated begomoviruses causing cotton leaf curl disease (CLCuD) that causes significant losses to a mainstay of the economy of Pakistan, cotton. RNA interference (RNAi) or gene silencing is a natural defense response of plants against invading viruses. In counter-defense, viruses encode suppressors of gene silencing that allow them to effectively invade plants. Here, we have analyzed the ability of the begomovirus Cotton leaf curl Multan virus (CLCuMV) and its associated betasatellite, Cotton leaf curl Multan β-satellite (CLCuMB) which, together, cause CLCuD, and the nonessential alphasatellite (Cotton leaf curl Multan alphasatellite [CLCuMA]) for their ability to suppress gene silencing in Nicotiana benthamiana. The results showed that CLCuMV by itself was unable to efficiently block silencing. However, in the presence of the betasatellite, gene silencing was entirely suppressed. Silencing was not affected in any way when infections included CLCuMA, although the alphasatellite was, for the first time, shown to be a target of RNA silencing, inducing the production in planta of specific small interfering RNAs, the effectors of silencing. Subsequently, using a quantitative real-time polymerase chain reaction assay and Northern blot analysis, the ability of all proteins encoded by CLCuMV and CLCuMB were assessed for their ability to suppress RNAi and the relative strengths of their suppression activity were compared. The analysis showed that the V2, C2, C4, and βC1 proteins exhibited suppressor activity, with the V2 showing the strongest activity. In addition, V2, C4, and βC1 were examined for their ability to bind RNA and shown to have distinct specificities. Although each of these proteins has, for other begomoviruses or betasatellites, been previously shown to have suppressor activity, this is the first time all proteins encoded by a geminiviruses (or begomovirus-betasatellite complex) have been examined and also the first for which four separate suppressors have been identified.
Behavioural flexibility and problem-solving in a tropical lizard
Authors: Leal Manuel , Powell Brian J.
Published: July 2011

The role of behavioural flexibility in responding to new or changing environmental challenges is a central theme in cognitive ecology. Studies of behavioural flexibility have focused mostly on mammals and birds because theory predicts that behavioural flexibility is favoured in species or clades that exploit a diversity of habitats or food sources and/or have complex social structure, attributes not associated with ectothermic vertebrates. Here, we present the results of a series of experiments designed to test cognitive abilities across multiple cognitive modules in a tropical arboreal lizard:
Anolis evermanni
. This lizard shows behavioural flexibility across multiple cognitive tasks, including solving a novel motor task using multiple strategies and reversal learning, as well as rapid associative learning. This flexibility was unexpected because lizards are commonly believed to have limited cognitive abilities and highly stereotyped behaviour. Our findings indicate that the cognitive abilities of
A. evermanni
are comparable with those of some endothermic species that are recognized to be highly flexible, and strongly suggest a re-thinking of our understanding of the cognitive abilities of ectothermic tetrapods and of the factors favouring the evolution of behavioural flexibility.
High activity and Lévy searches: jellyfish can search the water column like fish
Authors: Hays Graeme C. , Bastian Thomas , Doyle Thomas K. , Fossette Sabrina , Gleiss Adrian C. , Gravenor Michael B. , Hobson Victoria J. , Humphries Nicolas E. , Lilley Martin K. S. , Pade Nicolas G. , Sims David W.
Published: July 2011

Over-fishing may lead to a decrease in fish abundance and a proliferation of jellyfish. Active movements and prey search might be thought to provide a competitive advantage for fish, but here we use data-loggers to show that the frequently occurring coastal jellyfish (
Rhizostoma octopus
) does not simply passively drift to encounter prey. Jellyfish (327 days of data from 25 jellyfish with depth collected every 1 min) showed very dynamic vertical movements, with their integrated vertical movement averaging 619.2 m d
−1
, more than 60 times the water depth where they were tagged. The majority of movement patterns were best approximated by exponential models describing normal random walks. However, jellyfish also showed switching behaviour from exponential patterns to patterns best fitted by a truncated Lévy distribution with exponents (mean
μ
= 1.96, range 1.2–2.9) close to the theoretical optimum for searching for sparse prey (
μ
opt
≈ 2.0). Complex movements in these ‘simple’ animals may help jellyfish to compete effectively with fish for plankton prey, which may enhance their ability to increase in dominance in perturbed ocean systems.
High potential for formation and persistence of chimeras following aggregated larval settlement in the broadcast spawning coral,
Acropora millepora
Authors: Puill-Stephan E. , van Oppen M. J. H. , Pichavant-Rafini K. , Willis B. L.
Published: July 2011

In sessile modular marine invertebrates, chimeras can originate from fusions of closely settling larvae or of colonies that come into contact through growth or movement. While it has been shown that juveniles of brooding corals fuse under experimental conditions, chimera formation in broadcast spawning corals, the most abundant group of reef corals, has not been examined. This study explores the capacity of the broadcast spawning coral
Acropora millepora
to form chimeras under experimental conditions and to persist as chimeras in the field. Under experimental conditions, 1.5-fold more larvae settled in aggregations than solitarily, and analyses of nine microsatellite loci revealed that 50 per cent of juveniles tested harboured different genotypes within the same colony. Significantly, some chimeric colonies persisted for 23 months post-settlement, when the study ended. Genotypes within persisting chimeric colonies all showed a high level of relatedness, whereas rejecting colonies displayed variable levels of relatedness. The nearly threefold greater sizes of chimeras compared with solitary juveniles, from settlement through to at least three months, suggest that chimerism is likely to be an important strategy for maximizing survival of vulnerable early life-history stages of corals, although longer-term studies are required to more fully explore the potential benefits of chimerism.
Accuracy of ten isoflurane vaporisers in current clinical use
Authors: Kelly J. M. , Kong K.‐L.
Published: July 2011

There is a lack of independent data regarding the accuracy of isoflurane vaporisers in current clinical use. We studied the accuracy of 10 isoflurane vaporisers (six Penlon Sigma Delta, four Datex‐Ohmeda Isotec 5) taken from our operating theatres and anaesthetic rooms. Isoflurane output was measured at a range of fresh gas flow rates using both 100% oxygen and a 1:2 oxygen:nitrous oxide mixture as carrier gas. Within a clinical range of fresh gas flow rates (1–6 l.min−1) the worst relative output deviation of each vaporiser was at least ±20%, with under‐delivery of isoflurane being commoner than over‐delivery. Relative output deviation ranged from −62% to +21%, which could lead to a risk of awareness or overdose. Despite the existence of an in‐house calibration schedule, the vaporisers we found in current clinical use under‐ or occasionally over‐delivered isoflurane to a dangerous and unpredictable extent.
Risk factors for high‐risk human papillomavirus infection in unscreened Malian women
Authors: Tracy J. Kathleen , Traore Cheick B. , Bakarou Kamate , Dembelé Rokiatou , Coulibaly Rokiatou C. , Sow Samba O.
Published: July 2011

Objective  To investigate the epidemiology of human papillomavirus (HPV) infection in Malian women, for whom cervical cancer is the most common cancer and the second most common cause of cancer‐related mortality.

Methods  Pilot study of 202 women aged 15–65 to determine the prevalence rate of high‐risk HPV infection among unscreened Malian women. Information on risk factors was collected through a standardized, structured interview and clinical examination. High‐risk (HR) HPV DNA was detected using signal amplification methods (hybrid capture II).

Results  High‐risk HPV DNA was detected in 12% of unscreened women, while visual inspection after application of acetic acid and Lugol’s iodine (VIA/VILI) identified suspicious abnormalities in 2.5% of unscreened women. Histopathological evaluation of VIA/VILI‐positive biopsies revealed no evidence of cervical intraepithelial neoplasia or cervical cancer. The majority of infections occurred among women in the 15–24 year old range. Compared to women who were married or widowed, single women were 3.5 times more likely to be infected with HR HPV.

Conclusions  The prevalence of infection with cancer causing types of HPV in this study was 12%. These prevalence estimates are consistent with what has been reported previously for other West African countries.
Synthesis, Antifungal Activity, and Docking Study of Some New 1,2,4‐triazole Analogs
Authors: Sangshetti Jaiprakash N. , Lokwani Deepak K. , Sarkate Aniket P. , Shinde Devanand B.
Published: July 2011

Synthesis of new series of 1,2,4‐triazole with 1,2,3‐triazole and piperidine ring using ZrOCl2·8H2O as a catalyst in ethanol has been described. The yields obtained are in the range of 80–85%. All the synthesized compounds (3a–3o) are novel and were evaluated for their in vitro antifungal activities using standard agar method. Docking study of the newly synthesized compounds was performed, and results showed that all new compounds have similar binding mode in the active site of fungal enzyme P450 cytochrome lanosterol 14α‐demethylase.
O-011 Multimodality management of spetzler-martin grade III arteriovenous malformations
Authors: Pandey P , Steinberg G , Harraher C , Dodd R , Do H , Marks M
Published: July 2011

Introduction

Grade 3 AVMs are diverse due to variations in size (S), location in eloquent cortex (E) and presence of central venous drainage (V). These variations may have implications for management and outcome which were evaluated in this study.

Methods

100 patients with grade 3 AVMs were treated from 1984 to 2010. The AVMs were categorized by Spetzler-Martin characteristics as follows: Type 1, S1E1V1, Type 2 S2E1V0, Type 3 S2E0V1 and Type 4 S3E0V0. The occurrence of new neurological deficit, functional status (mRS) at discharge and follow-up, and radiological obliteration were correlated with demographic and morphologic characteristics.

Results

100 patients (49f, 51 m, age 5–68 years, mean 35.8 years) were evaluated. Size of AVMs were <3 cm (28), 3–6 cm (71) and >6 cm (1); 86 AVMs were in eloquent cortex, and 38 had central drainage. The AVMS were type 1 (28), type 2 (60), type 3 (11) and type 4 (1). Embolization was performed in 77 patients (175 procedures), surgery in 64 patients (74 surgeries), and radiosurgery in 49 patients (44 primary, 5 postoperative). Mortality following the management of these AVMs was 1%. 14 patients (14%) had new neurological deficits, with 5 (5%) disabling (mRS >2), and 9 (9%) non-disabling (mRS <2) events. Patients with type 1 AVM (small AVMs) had the best outcome, with 1/28 (3.6%) having a new neurological deficit as compared to larger AVMs (13/72, 16.7%, p<0.002). Older age (>40 years), size >3 cm, and non-hemorrhagic presentation predicted occurrence of new deficits (p<0.002). Gender, eloquence and venous drainage did not confer any benefit. 89 patients had adequate follow-up to be included in the obliteration analysis. AVM was obliterated in 78 patients (87.6%), 69 of them (78.6%) on angiogram and 9 on MRI/MRA. There was no difference between obliteration rates between different types of AVMs, Size, eloquence and drainage. Age, gender and clinical presentation also did not predict obliteration.

Conclusions

Multi-modality management of Grade III AVMs results in a high rate of obliteration which does not appear to be influenced by size, venous drainage or eloquent location. However, the development of new neurologic deficits did correlate with size, while eloquence and venous drainage did not influence this. We propose sub-classifying the grade III AVMs according to their size (<3 cm and >3 cm) to account for treatment risk.
P-010 A Study of the novel 054 Penumbra aspiration device in the ICA and MCA
Authors: Frei D , Bellon R , Huddle D , Dooley G , Gerber J , Turk A , Heck D , Hui F , Joseph G , Jahan R , Miskolczi L , Carpenter J , Grobelny T , Goddard J , Leader B , Bose A , Sit S P
Published: July 2011

Purpose

The 054 reperfusion catheter is a newly introduced component of the Penumbra System specifically designed to enhance aspiration efficiency by increasing the catheter diameter. The goal of this study was to compare its safety and effectiveness in reducing clot burden in the internal carotid artery (ICA) and the middle cerebral artery (MCA).

Methods and Materials

This study was a retrospective case review of 74 consecutive patients at 11 international centers with ICA or MCA occlusion who were treated with the Penumbra System. All patients reviewed presented to the hospital within 8 h of symptom onset with a treatable large vessel occlusion (TIMI 0 or 1). The primary endpoint was the rate of successful recanalization as defined by TIMI scores of 2–3.

Results

Mean baseline values at enrollment were age 65 years, median NIHSS score 18 (range 2–38), 61% were females, and the median time from symptom onset to arterial puncture was 5 h. After use of the Penumbra System, 91.8% of the treated vessels were revascularized to TIMI 2 or 3. Median time of aspiration was 18 min. Four procedural/device related SAEs were reported in three patients (5.4%). There were a total of 8 (10.8%) symptomatic ICHs reported at 24 h. At 90 days, all cause mortality was 23.0%. Of the 54 patients who either died or reached the 90 days follow-up, 20 (37.0%) had mRS scores of <2. Below are comparisons of the results in the ICA and MCA:

Conclusions

These results suggest that in acute stroke patients with large vessel occlusion, the 054 reperfusion catheter is equi-effective in the reduction of clot burden in the ICA and MCA.

Abstract P-010 Table 1All patients (N=74)ICA (N=18)MCA (N=52)TIMI 2–391.8%100%88.5%Procedure/device-related SAEs5.4%5.6%5.7%Death at 90 days23.0%22.2%23.1%
P-014 Venous sinus pulsatility in manometry evaluation of dural sinus narrowing in idiopathic intracranial hypertension
Authors: Lazzaro M , Zaidat O , Darkhabani Z , Fitzsimmons B
Published: July 2011

Introduction

Idiopathic intracranial hypertension (IIH) remains a poorly understood and therapeutically challenging disease. Enthusiasm has emerged for endovascular therapy with stent reconstruction of dural sinus narrowing, however a complete understanding of the hydrodynamic dysequilibrium is lacking. Few reports have characterized catheter manometry findings and none have addressed the pulsatility of the venous sinuses in IIH.

Methods

We reviewed all cases of patients referred for endovascular evaluation of medically refractory IIH. Patients with venous sinus pulsatility attenuation after stent implantation were identified. Chart and imaging review was performed.

Results

Two patients were identified with transverse sinus narrowing who underwent stent implantation with demonstrable attenuation of high venous pulsatility. Both cases demonstrated high pressure gradient across the focal narrowing (>30 mm Hg) and >70% stenosis. Mid-term follow-up revealed persistent clinical improvement.

Conclusions

We report the finding of high venous sinus pulsatility attenuation after stent implantation for dural sinus narrowing and propose the hypothesis that this finding is a marker of advanced dural sinus incompetence. This characteristic may be useful in identifying patients who would benefit from endovascular stent remodeling.
P-015 Initial experience with a coaxial dual-lumen balloon catheter for wide-neck aneurysm coil embolization
Authors: Lazzaro M , Zaidat O , Badruddin A , Fitzsimmons B
Published: July 2011

Introduction

Techniques for coil-embolization of wide-neck cerebral aneurysms include the use of stents and temporary occlusion with compliant non-detachable balloons to achieve safe and densely packed coil positioning. We describe the use of a new balloon device for wide-neck aneurysm treatment.

Methods

A single institution neuroendovascular device inventory was accessed to identify cases in which the Ascent balloon (Micrus Endovascular, San Jose, California, USA) was used for aneurysm coil embolization. Clinical, demographic, and angiographic data were obtained through chart review.

Results

Six cerebral aneurysm cases were treated using the Ascent balloon during the first 8-month period that the new device was available at our institution. Two of the patients presented with ruptured aneurysms. All aneurysms were large (maximum diameter 7 mm or greater) with an average neck length of 6.1 mm. Complete occlusion with coil embolization (Raymond class I) was achieved in all cases. The Ascent balloon was successfully positioned across the neck of the aneurysm in five patients, while delivery to the aneurysm neck was unsuccessful due to vessel tortuosity in one patient.

Conclusions

This initial experience demonstrates the feasibility, initial outcomes, and short-term follow-up results of a coaxial dual-lumen design balloon catheter used as an assistive device in coil embolization of wide-neck cerebral aneurysms. This new device contributes to the growing number of options for treatment of complex cerebral aneurysms.
P-032 Vascular reconstruction devices shrink small cerebral aneurysms
Authors: Nyberg E , Larson T
Published: July 2011

Endovascular treatment of intracranial aneurysms (IAs) often includes the deployment of a vascular reconstruction device (VRD), particularly if the aneurysm has a wide neck or unfavorable dome to neck ratio, to prevent coil herniation and to facilitate increased packing density. However other benefits may be hemodynamic and physiologic, that is, through flow diversion, reduced wall shear stress (WSS), and the provision of a scaffolding to support endotheliazation over the aneurysm neck. Hemodynamic simulations using computational flow dynamics suggest that the effect of flow diversion exerted by the Enterprise VRD decreases flow velocity in the aneurysm, increases stasis and decreases WSS, however to our knowledge clinical examples have not been published. We present four cases of staged, elective treatment of small saccular intracranial aneurysms in which placement of a single Enterprise VRD or Wingspan stent alone prompted beneficial aneurysm remodeling such that by the time of the planned coiling several weeks later these aneurysms had substantially decreased in size and it was felt that coil embolization was no longer feasible. We surmise that the VRDs in our series improved hemodynamic conditions enabling aneurysm shrinkage. This may have been accomplished in part by flow diversion by the device struts as simulations have predicted. However, another mechanism of remodeling may involve changing the geometry of the aneurysm and parent vessel. Increased WSS and WSS gradients are often found at vascular branch points or curvatures, therefore straightening of the parent vessel may be beneficial in these cases. All patients in our series demonstrated some degree of vessel straightening. Protrusion of device struts into the dome may also play a beneficial role. In summary, benefits of VRDs not directly related to coil packing may include flow diversion allowing for thrombotic retraction of the dome as well as decreased WSS and WSS gradients due to vessel straightening. Thus staging treatment in this manner may allow the aneurysm to shrink in some patients, thereby avoiding the risk of coil embolization. The long term prognosis of these tiny aneurysm remnants is unknown and these patients clearly need to be followed. Furthermore, whatever hemodynamic effects single VRDs may exert are unlikely to be effective in larger aneurysms, perhaps >3 mm.

Abstract P-032 Figure 1

Likely atherosclerotic aneurysm of the distal left vertebral artery (figure 1A and B) was initially treated with an Enterprise VRD. Short term follow up (figure 1C and D) demonstrates marked decrease in aneurysm size and partial vessel straightening.
E-003 Localization of spinal dural arteriovenous fistula: diagnosis and implications
Authors: Yen P , Maloney W , Schmidt M , Vandorpe R , Shankar J
Published: July 2011

Purpose

Spinal Dural Arteriovenous Fistula (SDAVF) is a rare acquired lesion that can impair spinal cord function. Early diagnosis is very important since the symptoms can be reversed if treated prior to irreversible cord ischemia or infarction. Characteristic features of the spinal MRI includes multi-leveled T2 hyperintensity in the spinal cord signifying cord edema and prominent flow voids in the extramedullary and intradural space from venous congestion. These prominent flow voids are commonly mistaken for primary vascular malformation. It is important to note that the flow voids are the consequence of venous congestion and not the site of fistulous shunting. The understanding of this disease process is pertinent in safe treatment planning. We aim to show that neither the distribution of flow voids nor the intramedullary findings are related to the location of the fistula.

Materials and Methods

We retrospectively analyzed cases of SDAVFs in the last 2 years. All patients underwent clinical examination, MRI of the whole spine and spinal digital subtraction angiogram (DSA). We compared the level of the fistula based on the clinical presentation and MR images with that of the DSA findings.

Results

There were a total of 7 cases of SDAVFs. All patients presented with progressive myelopathy. Initial MRI showed extensive T2 hyperintensity in the spinal cord and flow voids in the extramedullary, intradural space. Subsequent DSA identified the location of the fistula ranging from the cranio-cervical junction to the sacral level. Clinical presentation and MRI findings were not predictive of location of fistula found on spinal DSA. In one case, the patient's time resolved MR angiography was able to localize the fistula which was later confirmed on spinal DSA.

Discussion

SDAVFs represent an abnormal connection between the segmental dural arterial supply and the vein, which eventually drain into the perimedullary vein. This results in retrograde venous congestion in the spinal cord. This usually manifest as dilated perimedullary veins on MRI and T2 hyperintensity in spinal cord secondary to congestion and edema and clinically as progressive myelopathy. Since the spinal perimedullary venous system is an integrated system, congestion secondary to SDAVF at any spinal level can result in venous congestion of the spinal cord. Hence, the venous congestion is the consequence and not the cause and result in the characteristic clinical and MRI presentations. Only spinal DSA accurately demonstrate the fistula location. Standard contrast-enhanced MR angiography in combination with MRI has been shown recently to increase accuracy of fistula localization.

Clinical presentation and MRI findings are very useful in pointing toward the diagnosis of SDAVF but do not give any indication about of the location of fistula. Location of fistula can be shown only on spinal DSA or in some cases time resolved MR angiography. This understanding is very important in the planning of safe treatment.
O-007 Decreases in temperature and relative humidity leading to an increased incidence of ischemic stroke
Authors: Petrov D , Hidalgo A , Gandhi C , Prestigiacomo C
Published: July 2011

Introduction

The influence of meteorological variables on the incidence of ischemic stroke has been described in neurological literature. The link between weather conditions and overall morbidity and mortality has been established, with an increase during the winter months and during periods of extreme heat. Conversely, certain studies have established a link between lower temperatures and ischemic events. The equivocal data demands further inquiry into the connection between weather variable and ischemic events. Since certain studies on the association of stroke and meteorological variable are based in areas of very specific, extreme weather patterns the results may not be generalizable to more temperate climates. We aim to investigate the role of meteorological variables on the rate of ischemic events in a representative east coast inner city population.

Methods

A database of stroke patients treated at University Hospital in Newark, NJ, from 7.2009 to 7.2010 was used. Standardized data collection were utilized, including demographic, relevant medical history, medications, laboratory data on admission, vitals on admission, and disease course. Consecutive days with stroke admissions as well as singleton days with multiple stroke admissions were classified as clusters. Data from the national weather database data from the event dates recorded at the Newark airport weather station located 5.4 miles from University Hospital as well as the weather underground database (wunderground.com), collected 1.1 miles away from University Hospital was compared on ischemic event vs no ischemic event days as well as cluster vs non-cluster days. Data were analyzed using ANOVA to compare weather parameter as follows: (1) dates with ischemic events to days without ischemic event; (2) cluster vs non-cluster days.

Results

During the study period, 297 ischemic events were treated at University Hospital, 267 with ischemic stroke and 30 with TIA. The variation of monthly admission rates was insignificant. Analysis of the data revealed a statistically significant correlation between a decrease in max temperature, min temperature, average temp, dew point, and wet bulb temperature and an increased incidence of stroke. Likewise, a statistically significant decrease in those variables was also associated with increased clustering of ischemic events (p<0.01).

Conclusion

Lower temperatures as well decrease in relative humidity (measured by wet bulb temperature and dew point) are associated with an increased hospital admission rate for ischemic stroke and TIA.
E-014 The “sandwich” technique for interventional management of AIS
Authors: Crudup J , Hartley B , Baxter B
Published: July 2011

Introduction

Devices currently used in the endovascular treatment of acute ischemic stroke employ either aspiration or mechanical thrombectomy separately but not in combination. Recent advancements in catheter design have made the delivery of coaxial catheters to the intracranial occlusive lesion standard practice. At our institution, we have found the use of Concentrics Distal Access Catheter (DAC) adjunctively with a thrombectomy device to be effective in increasing catheter stability and enhancing clot retrieval. Further, we have found a novel use of the DAC during mechanical thrombectomy. With the DAC tip being placed at or within the proximal end of the clot and the retriever embedded distally in the clot, we employ aspiration through the DAC during the retrieval process. The clot is “sandwiched” between the combined forces of aspiration and mechanical extraction. DAC carries an approval for aspiration in Europe and Canada, but in the USA this is an off label use of the catheter. The aim of this “sandwich” technique is to enhance the thrombectomy procedure by decreasing the number of passes required and shortening the time to revascularization.

Methods

A retrospective review of mechanical thrombectomy cases performed at our institution after introduction of the DAC was conducted. Cases were reviewed from November 24, 2008 to April 1, 2011. From these cases, 25 were found in which the “sandwich” technique was utilized. The imaging and procedural reports were reviewed to insure that an appropriate and consistent “sandwich” technique was performed. Outcome measures analyzed were the rate of successful revascularization (using the TICI scoring system), 90-day Modified Rankin Scale (mRS) score, and the 90-day mortality rate.

Results

25 patients were identified (mean age, 65 years; gender, males 48%, females 52%; mean baseline NIHSS, 18). Successful revascularization (defined as achieving a TICI score of 2a, 2b or 3) was achieved in 20/25 (80%) patients. The rate of good outcomes (defined as a 90-day mRS 0–2) was achieved in 11/25 (44%). The 90-day mortality rate was 32% (8/25).

Conclusions

The “sandwich” technique yields favorable successful revascularization rates and good clinical outcomes as compared to current endovascular therapies reported in the literature for acute ischemic stroke treatment. Although not initially intended for this purpose, we feel that using the DAC to adjunctively aspirate during the mechanical thrombectomy procedure to be helpful. Further study in a larger patient population to explore whether this technique offers benefit over “traditional” thrombectomy is required.
CYB5D2 enhances HeLa cells survival of etoposide-induced cytotoxicity
Authors: Xie Yanyun , Bruce Anthony , He Lizhi , Wei Fengxiang , Tao Lijian , Tang Damu
Published: July 2011

Cytochrome b5 domain containing 2 (CYB5D2) (neuferricin) belongs to the family of membrane-associated progesterone receptors (MAPRs). MAPRs affect multiple cellular processes, including proliferation, differentiation, and survival. Consistent with these observations, we report here that CYB5D2 enhances HeLa cells survival of etoposide (ETOP)-mediated cytotoxicity. Overexpression of CYB5D2 enhanced the survival of HeLa cells compared with HeLa cells transfected with empty vector (EV) upon ETOP treatment. As ETOP initiates ATM-dependent DNA damage response (DDR), we were able to show that CYB5D2 did not affect ETOP-induced DDR. In line with these observations, CYB5D2 did not protect HeLa cells from UV-induced cytotoxicity. Additionally, CYB5D2 had no effects on TNFα-induced apoptosis. Collectively, CYB5D2 enhances HeLa cell survival of ETOP-induced cytotoxicity with some specificity. CYB5D2 contains a cytochrome b5 (cyt-b5) domain and a transmembrane (TM) motif. Both domains are required for CYB5D2-mediated protection of HeLa cells from ETOP-induced cytotoxicity. In an effort to search for the underlying mechanisms, we have profiled gene expression between HeLa–CYB5D2 and HeLa–EV cells. Although ectopic CYB5D2 does not massively alter gene expression, the expression of several transcripts was affected more than 2-fold, suggesting that they may contribute to CYB5D2-mediated HeLa cell survival of ETOP treatment.
EVERY N2-LOCALLY CONNECTED CLAW-FREE GRAPH WITH MINIMUM DEGREE AT LEAST 7 IS Z3-CONNECTED
Authors: WEI ERLING , CHEN YE , LI PING , LAI HONG-JIAN
Published: July 2011

Let G be a 2-edge-connected undirected graph, A be an (additive) abelian group and A* = A-{0}. A graph G is A-connected if G has an orientation D(G) such that for every function b : V(G) ↦ A satisfying Συ∈V(G)b(υ) = 0, there is a function f : E(G) ↦ A* such that for each vertex υ ∈ V(G), the total amount of f values on the edges directed out from υ minus the total amount of f values on the edges directed into υ equals b(υ). Let Z3denote the group of order 3. Jaeger et al. conjectured that there exists an integer k such that every k-edge-connected graph is Z3-connected. In this paper, we prove that every N2-locally connected claw-free graph G with minimum degree δ(G) ≥ 7 is Z3-connected.
Association between Essential Tremor and Other Neurodegenerative Diseases: What Is the Epidemiological Evidence
Authors: LaRoia Hiral , Louis Elan D.
Published: July 2011

Background: The possible links between essential tremor (ET) and Parkinson’s disease (PD) and, more recently, between ET and Alzheimer’s disease (AD) have been of great interest, particularly with the emergence of postmortem data suggesting that ET itself may be a neurodegenerative disease. Given the very high population prevalence of ET, its possible role as a risk factor for PD and AD is of special significance. At the center of this debate is the burgeoning evidence from epidemiological studies, examining whether there is an increased co-occurrence of these conditions within the same individuals or within families. Methods: We conducted a PubMed search from 1966 to March 2011 and reviewed the epidemiological evidence, restricting our analyses to studies that generated quantifiable measures of association (odds ratios or relative risks), thereby being able to assess the role of chance. Results: The most robust evidence, from case-control, prospective and familial aggregation studies, indicates that ET is associated with increased odds and increased risks of both PD and AD. Conclusions: There is reasonable epidemiological evidence to support a link between ET and these neurodegenerative diseases. Further studies are needed to corroborate the current results, provide additional estimates of effect and begin to explore the mechanistic underpinnings for these intriguing associations.
Impacts of the Lowest Model Level Height on the Performance of Planetary Boundary Layer Parameterizations
Authors: Shin Hyeyum Hailey , Hong Song-You , Dudhia Jimy
Published: July 2011

The lowest model level height z1 is important in atmospheric numerical models, since surface layer similarity is applied to the height in most of the models. This indicates an implicit assumption that z1 is within the surface layer. In this study, impacts of z1 on the performance of planetary boundary layer (PBL) parameterizations are investigated. Three conceptually different schemes in the Weather Research and Forecasting (WRF) model are tested for one complete diurnal cycle: the nonlocal, first-order Yonsei University (YSU) and Asymmetric Convective Model version 2 (ACM2) schemes and the local, 1.5-order Mellor–Yamada–Janjić (MYJ) scheme.

Surface variables are sensitive to z1 in daytime when z1 is below 12 m, even though the height is within the surface layer. Meanwhile during nighttime, the variables are systematically altered as z1 becomes shallower from 40 m. PBL structures show the sensitivity in the similar manner, but weaker. The order of sensitivity among the three schemes is YSU, ACM2, and MYJ. The significant sensitivity of the YSU parameterization comes from the PBL height calculation. This is considerably alleviated by excluding the thermal excess term in determining the PBL height when z1 is within the surface layer. The factor that specifies the ratio of nonlocal transport to total mixing is critical to the sensitivity of the ACM2 scheme. The MYJ scheme has no systematic sensitivity, since it is a local scheme. It is also noted that a numerical instability appears accompanying the unrealistic PBL structures when the grid spacing in the surface layer suddenly jumps.
Mouse sperm undergo GPI-anchored protein release associated with lipid raft reorganization and acrosome reaction to acquire fertility
Authors: Watanabe Hitomi , Kondoh Gen
Published: July 2011

Mammalian sperm undergo several maturation steps after leaving the testis to become competent for fertilization. Important changes occur in sperm within the female reproductive tract, although the molecular mechanisms underlying these processes remain unclear. To investigate sperm membrane remodeling upon sperm maturation, we developed transgenic mouse lines carrying glycosylphosphatidylinositol (GPI)-anchored enhanced green fluorescent protein (EGFP–GPI) and traced the fate of this fluorescent protein during the fertility-acquiring process in sperm in vitro and in vivo. When the GFP-labeled sperm were treated with compounds for promoting the acrosome reaction, EGFP–GPI was released from the sperm surface crosslinked with characteristic relocation of a lipid raft marker ganglioside GM1. Sperm ejaculated into the uterus strongly expressed EGFP–GPI in the head region, whereas a part of the oviductal sperm lost fluorescence in a manner that was dependent on the presence of angiotensin-converting enzyme (ACE). Moreover, sperm on the zona pellucida of eggs in the oviduct were all found to have low levels of GFP. These results suggest that sperm undergoing GPI-anchored protein release associated with reorganization of lipid rafts and the acrosome reaction acquire fertilization potential.