bluuebunny/crossref_metadata_2025_split huggingface dataset:
Flow‐sensitive 4D MRI of the thoracic aorta: Comparison of image quality, quantitative flow, and wall parameters at 1.5 T and 3 T
Authors: Strecker Christoph , Harloff Andreas , Wallis Wolf , Markl Michael 
Published: June 2012

AbstractPurpose:To evaluate the effect of field strength on flow‐sensitive 4D magnetic resonance imaging (MRI) of the thoracic aorta. A volunteer study at 1.5 T and 3 T was conducted to compare phase‐contrast MR angiography (MRA) and 3D flow visualization quality as well as quantification of aortic hemodynamics.Materials and Methods:Ten healthy volunteers were examined by flow‐sensitive 4D MRI at both 1.5 T and 3 T MRI with identical imaging parameters (TE/TR = 6/5.1 msec, spatial/temporal resolution ≈2 mm/40.8 msec). Analysis included assessment of image quality of derived aortic 3D phase contrast (PC) angiography and 3D flow visualization (semiquantitative grading on a 0–2 scale, two blinded observers) and quantification of blood flow velocities, net flow per cardiac cycle, wall shear stress (WSS), and velocity noise.Results:Quality of 3D blood flow visualization (average grading = 1.8 ± 0.4 at 3 T vs. 1.1 ± 0.7 at 1.5 T) and the depiction of aortic lumen geometry by 3D PC‐MRA (1.7 ± 0.5 vs. 1.2 ± 0.6) were significantly (P < 0.01) improved at 3 T while velocity noise was significantly higher (P < 0.01) at 1.5 T. Velocity quantification resulted in minimally altered (0.05 m/s, 3 mL/cycle and 0.01 N/m2) but not statistically different (P = 0.40, P = 0.39, and P = 0.82) systolic peak velocities, net flow, and WSS for 1.5 T compared to 3 T.Conclusion:Flow‐sensitive 4D MRI at 3 T provided improved image quality without additional artifacts related to higher fields. Imaging at 1.5 T MRI, which is more widely available, was also feasible and provided information on aortic 3D hemodynamics of moderate quality with identical performance regarding quantitative analysis. J. Magn. Reson. Imaging 2012;36:1097–1103. © 2012 Wiley Periodicals, Inc.
Real‐time flow with fast GPU reconstruction for continuous assessment of cardiac output
Authors: Kowalik Grzegorz Tomasz , Steeden Jennifer Anne , Pandya Bejal , Odille Freddy , Atkinson David , Taylor Andrew , Muthurangu Vivek 
Published: June 2012

AbstractPurpose:To demonstrate the feasibility of real‐time phase contrast magnetic resonance (PCMR) assessment of continuous cardiac output with a heterogeneous (CPU/GPU) system for online image reconstruction.Materials and Methods:Twenty healthy volunteers underwent aortic flow examination during exercise using a real‐time spiral PCMR sequence. Acquired data were reconstructed in online fashion using an iterative sensitivity encoding (SENSE) algorithm implemented on an external computer equipped with a GPU card. Importantly, data were sent back to the scanner console for viewing. A multithreaded CPU implementation of the real‐time PCMR reconstruction was used as a reference point for the online GPU reconstruction assessment and validation. A semiautomated segmentation and registration algorithm was applied for flow data analysis.Results:There was good agreement between the GPU and CPU reconstruction (−0.4 ± 0.8 mL). There was a significant speed‐up compared to the CPU reconstruction (15×). This translated into the flow data being available on the scanner console ≈9 seconds after acquisition finished. This compares to an estimated time using the CPU implementation of 83 minutes.Conclusion:Our heterogeneous image reconstruction system provides a base for translation of complex MRI algorithms into clinical workflow. We demonstrated its feasibility using real‐time PCMR assessment of continuous cardiac output as an example. J. Magn. Reson. Imaging 2012; 36:1477–1482. © 2012 Wiley Periodicals, Inc.
Characterization of some Middle European soil textures by gamma‐spectrometry
Authors: Petersen Hauke , Wunderlich Tina , Attia al Hagrey Said , Rabbel Wolfgang 
Published: June 2012

AbstractInformation about the variability of different soil attributes within a field is essential for sustainable land management and precision agriculture. Mobile proximal gamma‐ray spectrometry can map soil characteristics of vast areas at different scales rapidly and cost‐effectively. This study aims at investigating reliability and capability of mobile‐gamma‐spectrometry (radiometrics) data to map typical soils of Middle Europe. In this paper, we investigate relationships between the radioelement concentrations (K, U, Th, and dose rate) and soil parameters (texture, CEC, pH, and organic‐C content) at four different field sites and soil textures. The data reliability is confirmed at the survey start. Mobile data have an excellent linear correlation (nearly 1:1) with the stationary readings (of identical devices, acquisition setups, and soil conditions) but moderate correlation with laboratory data (of different devices, setups, and sample conditions). Dried lab samples have systematically higher radioelement concentrations than the field soils (normally wet). Consequently, the mobile‐gamma‐spectrometric data is sufficiently accurate for soil mapping, and its calibration by laboratory data is less useful due to the varying environmental conditions. Single absolute radioelement concentrations show only moderate correlations with the different soil parameters, particularly clay content and CEC. This may be related to varying environmental conditions (soil moisture, soil structure, vegetation, land use, etc.) between the study sites. Investigations of the ratios of radioelement concentrations yield a clear improvement of their correlations to soil parameters, especially for sand and clay contents, CEC, and organic C. Additionally, multiple‐linear‐regression models were established using the element concentrations of potassium and thorium to predict silt content and pH. The results of the highly correlated models were confirmed by comparing with clay and silt content and pH value, respectively, to six additional independent field samples. Briefly, applications of gamma‐ray data for soil mapping offers the possibility of the development of quantitative relationships regarding soil parameters like sand and clay contents, CEC, and organic C. Classification of soil textures by gamma‐ray data seems to be promising, though a broader database of soils is needed for further research. We recommend gamma‐ray mapping as a complementary or even an alternative to common mapping techniques.
Is there an increased risk of hip fracture in Parkinson's disease? A nationwide inpatient sample
Authors: Bhattacharya Rajib K. , Dubinsky Richard M. , Lai Sue Min , Dubinsky Hilary 
Published: June 2012

AbstractObjective:The aim of this study was to determine whether people with Parkinson's disease (PD) are overrepresented in a national cohort of hip‐fracture admissions.Background:Frequent falls, combined with a higher rate of osteoporosis in people with PD, should lead to an increased risk of hip fracture.Methods:This work was a retrospective cohort analysis from the Nationwide Inpatient Sample from 1988 to 2007, a stratified sample of 20% of U.S. hospital admissions. Admissions with a primary diagnosis of acute hip fracture were identified, as was a subset with a secondary diagnosis of PD.Results:A total of 3.63% of 1,066,404 hip‐fracture admissions had PD. When compared to the population of prevalence among patients with hip fracture, the prevalence of PD was up to 4.48 times (95% confidence interval [CI]: 4.46, 4.49) more than predicted, and when adjusted for gender and age, it was 4.02 (95% CI: 4.00, 4.03).Conclusions:In this 20‐year nationwide sample of hip fractures, patients with PD were overrepresented by a factor of 4. © 2012 Movement Disorder Society
Subthalamic activity during diphasic dyskinesias in Parkinson's disease
Authors: Alegre Manuel , López‐Azcárate Jon , Alonso‐Frech Fernando , Rodríguez‐Oroz Maria C. , Valencia Miguel , Guridi Jorge , Artieda Julio , Obeso José A. 
Published: June 2012

AbstractBackground:Diphasic dyskinesias are a subtype of levodopa‐induced dyskinesias that appear typically at the onset and end of levodopa antiparkinsonian action. The pathophysiology of diphasic dyskinesias is not well understood.Methods:We analyzed local field potentials recorded from the subthalamic nucleus in 7 Parkinson's disease (PD) patients who showed typical diphasic dyskinesias during postoperative recordings through a deep brain stimulation electrode. The evolution of the different oscillatory activities related to the onset and end of diphasic dyskinesias was studied by windowed fast Fourier transforms.Results:Typical “off”‐state beta activity disappeared with the onset of diphasic dyskinesias, whereas gamma activity was absent or minimal until their end. Theta activity during diphasic dyskinesias was similar to that observed during peak‐dose dyskinesias.Conclusions:From a neurophysiological viewpoint, patients exhibited oscillatory activity typical of the “on” medication state during diphasic dyskinesias. The minimal presence of gamma activity during diphasic dyskinesias, however, suggests that this “on” state might be incomplete or limited to dopaminergic mechanisms affecting the lower limbs. © 2012 Movement Disorder Society
Is transcranial sonography useful to distinguish scans without evidence of dopaminergic deficit patients from Parkinson's disease?
Authors: Stockner Heike , Schwingenschuh Petra , Djamshidian Atbin , Silveira‐Moriyama Laura , Katschnig Petra , Seppi Klaus , Dickson John , Edwards Mark J. , Lees Andrew J. , Poewe Werner , Bhatia Kailash P. 
Published: June 2012

AbstractBackground:Approximately 10% of patients clinically diagnosed with early Parkinson's disease (PD) subsequently have normal dopaminergic functional imaging. Transcranial sonography (TCS) has been shown to detect midbrain hyperechogenicity in approximately 90% of Parkinson's disease (PD) patients and 10% of the healthy population. The aim of this study was to investigate the prevalence of midbrain hyperechogenicity in patients with suspected parkinsonism and scans without evidence of dopaminergic deficit (SWEDD), in comparison to PD patients.Methods:TCS was performed in 14 patients with SWEDD and 19 PD patients.Results:There was a significantly increased area of echogenicity in the PD group (0.24 ± 0.06 cm2), compared to the group of patients with SWEDD (0.13 ± 0.06 cm2; P < 0.001). One (9.1%) of these patients, compared to 14 (82.5%) of the PD patients, was found to have hyperechogenicity (P < 0.001).Conclusions:We conclude that TCS is useful to distinguish PD patients from patients with suspected parkinsonism and SWEDD. © 2012 Movement Disorder Society
Analysis of a two‐level method for anisotropic diffusion equations on aligned and nonaligned grids
Authors: Yu Guozhu , Xu Jinchao , Zikatanov Ludmil T. 
Published: June 2012

SUMMARYThis paper is on the convergence analysis for two‐grid and multigrid methods for linear systems arising from conforming linear finite element discretization of the second‐order elliptic equations with anisotropic diffusion. The multigrid algorithm with a line smoother is known to behave well when the discretization grid is aligned with the anisotropic direction; however, this is not the case with a nonaligned grid. The analysis in this paper is mainly focused on two‐level algorithms. For aligned grids, a lower bound is given for a pointwise smoother, and this bound shows a deterioration in the convergence rate, whereas for ‘maximally’ nonaligned grids (with no edges in the triangulation parallel to the direction of the anisotropy), the pointwise smoother results in a robust convergence. With a specially designed block smoother, we show that, for both aligned and nonaligned grids, the convergence is uniform with respect to the anisotropy ratio and the mesh size in the energy norm. The analysis is complemented by numerical experiments that confirm the theoretical results. Copyright © 2012 John Wiley & Sons, Ltd.
Optimal drug dosing control for intensive care unit sedation by using a hybrid deterministic–stochastic pharmacokinetic and pharmacodynamic model
Authors: Gholami Behnood , Haddad Wassim M. , Bailey James M. , Tannenbaum Allen R. 
Published: June 2012

SUMMARYIn clinical intensive care unit practice, sedative/analgesic agents are titrated to achieve a specific level of sedation. The level of sedation is currently based on clinical scoring systems. Examples include the motor activity assessment scale, the Richmond agitation–sedation scale, and the modified Ramsay sedation scale. In general, the goal of the clinician is to find the drug dose that maintains the patient at a sedation score corresponding to a moderately sedated state. This is typically done empirically, administering a drug dose that usually is in the effective range for most patients, observing the patient's response, and then adjusting the dose accordingly. However, the response of patients to any drug dose is a reflection of the pharmacokinetic and pharmacodynamic properties of the drug and the specific patient. In this paper, we use pharmacokinetic and pharmacodynamic modeling to find an optimal drug dosing control policy to drive the patient to a desired modified Ramsay sedation scale score. Copyright © 2012 John Wiley & Sons, Ltd.
Narratives of Ugandan Women Adhering to HIV/AIDS Medication
Authors: Matovu Sarah Natalia , La cour Karen , Hemmingsson Helena 
Published: June 2012

AbstractAdherence to highly active antiretroviral therapy (HAART) is essential to improving the quality of life of people living with HIV/AIDS; however, it still remains a challenge especially for young African women. The purpose of the study was to explore how young women with HIV/AIDS in Uganda experience the influence of their everyday life occupations on adherence to HAART after more than 1 year on the medication.Narratives of six participants were elicited using two semistructured interviews within a period of 1 month. Narrative analysis was used to develop themes reflecting the participants' stories of coping with everyday activities.The participants described their adherence to HAART in relation to everyday life occupations as a “tug of war”, which describes the struggles they had taking medication because they were afraid of being discriminated by peers and the general society. They also expressed fear of not being included in many activities if people knew they have HIV/AIDS because there are many beliefs associated with the illness especially for young women in which they are branded promiscuous. However, in the Ugandan culture, women are considered to be home makers, which restricted their activities mostly around domestic work making it hard for them to prioritize their medication, and when they young women prioritized, it was all about fun activities that seemed to consume much time, hence contributing to the poor adherence. It is therefore important to assess the everyday occupations of young women before they start taking medication, so that HAART is scheduled in accordance with their everyday life occupation to reduce poor adherence.The implications of the study on practice is that it will enable occupational therapists working with persons with HIV/AIDS develop age‐specific activities taking into consideration HAART as an everyday life activity rather than one that needs to be incorporated into their already existing activities, hence improving their adherence and reducing on stigma associated to the medication. Copyright © 2012 John Wiley & Sons, Ltd.
Microwave‐Assisted Quick Synthesis of Some Potential High Explosives
Authors: Saikia Ananta , Sivabalan Renganathan , Gore Girish M. , Sikder Arun K. 
Published: June 2012

AbstractThis paper reports a novel microwave‐assisted method for the synthesis of potential high explosives (HEs) such as 3‐nitro‐1,2,4‐triazol‐5‐one (NTO), bis‐(2,2‐dinitropropyl) nitramine (BDNPN), 4‐nitroimidazole (4‐NI) and 2,4,6,8,10,12‐hexanitro‐2,4,6,8,10,12‐hexaazaisowurtzitane (CL‐20). The high temperature thermal rearrangement of 1,4‐dinitroimidazole to 2,4‐dinitroimidazole was also reported using microwave radiation as heating source. The synthesized compounds were characterized by spectroscopic techniques and the data obtained confirmed their structures.
Nongeminate recombination in organic bulk heterojunction solar cells: Contribution of exciton–polaron interaction
Authors: Szmytkowski Jȩdrzej 
Published: June 2012

AbstractA new model to explain nongeminate recombination in organic bulk heterojunction solar cells is presented. We suggest that the annihilation of excitons on charge carriers at the interface between donor and acceptor phases competes with the bimolecular recombination of Coulombically bound electron–hole pairs. The exciton–polaron interaction gives visible contribution to the reduction of Langevin recombination. An analytical formula, which describes the reduction prefactor, has been derived. We demonstrate that exciton–charge carrier interactions cause an increase of the recombination order. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Distributed primal–dual stochastic subgradient algorithms for multi‐agent optimization under inequality constraints
Authors: Yuan Deming , Xu Shengyuan , Zhang Baoyong , Rong Lina 
Published: June 2012

SUMMARYWe consider the multi‐agent optimization problem where multiple agents try to cooperatively optimize the sum of their local convex objective functions, subject to global inequality constraints and a convex constraint set over a network. Through characterizing the primal and dual optimal solutions as the saddle points of the associated Lagrangian function, which can be evaluated with stochastic errors, we propose the distributed primal–dual stochastic subgradient algorithms for two cases: (i) the time model is synchronous and (ii) the time model is asynchronous. In the first case, we obtain bounds on the convergence properties of the algorithm for a diminishing step size. In the second case, for a constant step size, we establish some error bounds on the algorithm's performance. In particular, we prove that the error bounds scale as in the number of n agents. Copyright © 2012 John Wiley & Sons, Ltd.
Axonal loss and cognitive deficits in term infants with normal umbilical artery Doppler born small‐for‐gestational age
Authors: Pueyo V. , Oros D. , Valle S. , Tuquet H. , Güerri N. , Argüelles M. , Ventura P. 
Published: June 2012

AbstractObjectiveTo assess cognitive outcomes and structural changes in the central nervous system, the latter using a novel approach to examine changes in neuronal integrity of the optic nerve, in children at 5–6½ years of age who were born small‐for‐gestational age (SGA) at term having shown normal umbilical artery (UA) Doppler.MethodsWe compared neuronal damage, cognitive deficits and visuospatial perception in two cohorts of infants, one born SGA (n = 40) and one born appropriate‐for‐gestational age (AGA) (n = 39) in weight. Neuronal damage was evaluated using optical coherence tomography (OCT) of the optic nerve. Cognitive deficits were assessed with the Wechsler Preschool and Primary Scale of Intelligence (WPPSI) test. Visuospatial perception was evaluated with Rey‐Osterreich Complex Figure (ROCF) tasks.ResultsChildren from the SGA group had a significantly thinner average retinal nerve fiber layer (RNFL) compared with those from the AGA group (98.2 vs 104.5 µm, P = 0.012). Children from the SGA group exhibited impaired performance in copy tasks on the ROCF (3.27 vs 3.56, P = 0.036) and a higher rate of suboptimal WPPSI test performance intelligence quotient scores (15% vs 0%; P = 0.025) compared with those from the AGA group.ConclusionTerm infants with normal UA Doppler born SGA are at increased risk for cognitive deficits and axonal loss in the RNFL at the age of 5–6½ years. Copyright © 2012 ISUOG. Published by John Wiley & Sons, Ltd.
Three tokens in Herman’s algorithm
Authors: Kiefer Stefan , Murawski Andrzej S. , Ouaknine Joël , Wachter Björn , Worrell James 
Published: June 2012

Abstract

Herman’s algorithm is a synchronous randomized protocol for achieving self-stabilization in a token ring consisting of
N
processes. The interaction of tokens makes the dynamics of the protocol very difficult to analyze. In this paper we study the distribution of the time to stabilization, assuming that there are three tokens in the initial configuration. We show for arbitrary
N
and for an arbitrary timeout
t
that the probability of stabilization within time
t
is minimized by choosing as the initial three-token configuration the configuration in which the tokens are placed equidistantly on the ring. Our result strengthens a corollary of a theorem of McIver and Morgan (Inf. Process Lett. 94(2): 79–84,
2005
), which states that the
expected
stabilization time is minimized by the equidistant configuration.
Reconciling real and stochastic time: the need for probabilistic refinement
Authors: Markovski J. , D’Argenio P. R. , Baeten J. C. M. , de Vink E. P. 
Published: June 2012

Abstract
We conservatively extend an ACP-style discrete-time process theory with discrete stochastic delays. The semantics of the timed delays relies on time additivity and time determinism, which are properties that enable us to merge subsequent timed delays and to impose their synchronous expiration. Stochastic delays, however, interact with respect to a so-called race condition that determines the set of delays that expire first, which is guided by an (implicit) probabilistic choice. The race condition precludes the property of time additivity as the merger of stochastic delays alters this probabilistic behavior. To this end, we resolve the race condition using conditionally-distributed unit delays. We give a sound and ground-complete axiomatization of the process theory comprising the standard set of ACP-style operators. In this generalized setting, the alternative composition is no longer associative, so we have to resort to special normal forms that explicitly resolve the underlying race condition. Our treatment succeeds in the initial challenge to conservatively extend standard time with stochastic time. However, the ‘dissection’ of the stochastic delays to conditionally-distributed unit delays comes at a price, as we can no longer relate the resolved race condition to the original stochastic delays. We seek a solution in the field of probabilistic refinements that enable the interchange of probabilistic and nondeterministic choices.
Towards a linear algebra of programming
Authors: Oliveira José N. 
Published: June 2012

AbstractThe algebra of programming (AoP) is a discipline for programming from specifications using relation algebra. Specification vagueness and nondeterminism are captured by relations. (Final) implementations are functions. Probabilistic functions are half way between relations and functions: they express the propensity, or likelihood of ambiguous, multiple outputs. This paper puts forward a basis for a linear algebra of programming (LAoP) extending standard AoP towards probabilistic functions. Because of the quantitative essence of these functions, the allegory of binary relations which supports the AoP has to be extended. We show that, if one restricts to discrete probability spaces, categories of matrices provide adequate support for the extension, while preserving the pointfree reasoning style typical of the AoP.