bluuebunny/crossref_metadata_2025_split huggingface dataset:
Rosuvastatin treatment protects against nitrate‐induced oxidative stress in eNOS knockout mice: implication of the NAD(P)H oxidase pathway
Authors: Otto Anne , Fontaine Jeanine , Tschirhart Eric , Fontaine David , Berkenboom Guy 
Published: April 2006

Nitrate tolerance is associated with an enhanced superoxide anion (O2−) production and may be attenuated by statins as they interact with the two main endothelial NO synthase (eNOS) and NAD(P)H oxidase pathways involved in this oxidative stress.
Groups of wild‐type (wt, C57Bl/6J) and eNOS knock‐out mice (eNOS−/−) received rosuvastatin (20 mg kg−1 day−1 p.o.) for 5 weeks and a cotreatment with the statin plus nitroglycerin (NTG; 30 mg kg−1 day−1, subcutaneous injections b.i.d.) for the last 4 days. Another group received only NTG (30 mg kg−1 d−1, b.i.d. for 4 days) and finally control mice from both strains received no treatment.
Rings of thoracic aortas from these groups were studied in organ baths. Relaxations to NTG (0.1 nM–0.1 mM) were determined on thromboxane analogue (U44619)‐precontracted rings and O2− production (RLU 5 s−1 mg−1 of total protein content) was assessed in aorta homogenates with the lucigenin‐enhanced chemiluminescence technique. Reverse transcriptase–polymerase chain reaction analysis was performed on aortas from both mice strains.
In vivo NTG treatment induced a significant rightward shift of the concentration–effect curve to NTG compared to control group. There was, however, no cross‐tolerance with non‐nitrate sources of NO (unaltered response to acetylcholine in wt group). The rosuvastatin+NTG cotreatment was able to protect against the development of nitrate tolerance in both mice strains and L‐mevalonate abolished this protective effect of rosuvastatin.
In vivo treatment with apocynin, a purported NAD(P)H oxidase inhibitor, also produced a similar protection to that observed with rosuvastatin in both strains.
Superoxide anion formation was increased after NTG treatment in both mice strains and the rosuvastatin+NTG cotreatment was able to reduce that production.
Moreover, rosuvastatin treatment abolished the increase in gp91phox mRNA (an endothelial membrane NAD(P)H oxidase subunit) expression induced by in vivo exposure to NTG.
These findings suggest that long‐term rosuvastatin treatment protects against nitrate tolerance by counteracting NTG‐induced increase in O2− production, probably via a direct interaction with the NAD(P)H oxidase pathway.

British Journal of Pharmacology (2006) 148, 544–552. doi:10.1038/sj.bjp.0706738
Dynamics of Sheared Convective Boundary Layer Entrainment. Part I: Methodological Background and Large-Eddy Simulations
Authors: Conzemius Robert J. , Fedorovich Evgeni 
Published: April 2006

Abstract
The reported study examines the dynamics of entrainment and its effects on the evolution of the dry atmospheric convective boundary layer (CBL) when wind shear is present. The sheared CBL can be studied by means of direct measurements in the atmosphere, laboratory studies, and numerical techniques. The advantages and disadvantages of each technique are discussed in the present paper, which also describes the methodological background for studying the dynamics of entrainment in sheared CBLs. For the reported study, large-eddy simulation (LES) was chosen as the primary method of convective entrainment investigation. Twenty-four LES runs were conducted for CBLs growing under varying conditions of surface buoyancy flux, free-atmospheric stratification, and wind shear. The simulations were divided into three categories: CBL with no mean wind (NS), CBL with a height-constant geostrophic wind of 20 m s−1 (GC), and CBL with geostrophic wind shear (GS). In the simulated cases, the sheared CBLs grew fastest, relative to the NS CBLs, when the surface buoyancy flux was weak and the atmospheric stratification was moderate or weak.
Three fundamental findings resulted from the investigated CBL cases: (i) the entrainment zone shear is much more important than the surface shear in enhancing CBL entrainment, although entrainment zone shear is indirectly affected by surface shear; (ii) the sheared entrainment zone features a sublayer of nearly constant flux Richardson number, which points to a balance between shear production and buoyancy consumption of turbulence kinetic energy (TKE) that regulates entrainment; and (iii) the fraction of entrainment zone shear-generated TKE spent on the entrainment is lower than suggested by earlier studies.
Sensitivity of the Simulated Distributions of Water Masses, CFCs, and Bomb 14C to Parameterizations of Mesoscale Tracer Transports in a Model of the North Pacific
Authors: Xu Yongfu , Aoki Shigeaki , Harada Koh 
Published: April 2006

Abstract
A basinwide ocean general circulation model of the North Pacific Ocean is used to study the sensitivity of the simulated distributions of water masses, chlorofluorocarbons (CFCs), and bomb carbon-14 isotope (14C) to parameterizations of mesoscale tracer transports. Five simulations are conducted, including a run with the traditional horizontal mixing scheme and four runs with the isopycnal transport parameterization of Gent and McWilliams (GM). The four GM runs use different values of isopycnal and skew diffusivities. Simulated results show that the GM mixing scheme can help to form North Pacific Intermediate Water (NPIW). Greater isopycnal diffusivity enhances formation of NPIW. Although greater skew diffusivity can also generate NPIW, it makes the subsurface too fresh. Results from simulations of CFC uptake show that greater isopycnal diffusivity generates the best results relative to observations in the western North Pacific. The model generally underestimates the inventories of CFCs in the western North Pacific. The results from simulations of bomb 14C reproduce some observed features. Greater isopycnal diffusivity generates a longitudinal gradient of the inventory of bomb 14C from west to east, whereas greater skew diffusivity makes it reversed. It is considered that the ratio of isopycnal diffusivity to skew diffusivity is important. An increase in isopycnal diffusivity increases storage of passive tracers in the subtropical gyre.
A Consistent Diffusion–Dissipation Parameterization in the ECHAM Climate Model
Authors: Burkhardt Ulrike , Becker Erich 
Published: April 2006

Abstract
The diffusion–dissipation parameterizations usually adopted in GCMs are not physically consistent. Horizontal momentum diffusion, applied in the form of a hyperdiffusion, does not conserve angular momentum and the associated dissipative heating is commonly ignored. Dissipative heating associated with vertical momentum diffusion is often included, but in a way that is inconsistent with the second law of thermodynamics.
New, physically consistent, dissipative heating schemes due to horizontal diffusion (Becker) and vertical diffusion (Becker, and Boville and Bretherton) have been developed and tested. These schemes have now been implemented in 19- and 39-level versions of the ECHAM4 climate model. The new horizontal scheme requires the replacement of the hyperdiffusion with a ∇2 scheme.
Dissipation due to horizontal momentum diffusion is found to have maximum values in the upper troposphere/lower stratosphere in midlatitudes and in the winter hemispheric sponge layer, resulting in a warming of the area around the tropopause and of the polar vortex in Northern Hemispheric winter. Dissipation associated with vertical momentum diffusion is largest in the boundary layer. The change in parameterization acts to strengthen the vertical diffusion and therefore the associated dissipative heating. Dissipation due to vertical momentum diffusion has an indirect effect on the upper-tropospheric/stratospheric temperature field in northern winter, which is to cool and strengthen the northern polar vortex. The warming in the area of the tropopause resulting from the change in both dissipation parameterizations is quite similar in both model versions, whereas the response in the temperature of the northern polar vortex depends on the model version.
Subependymomas: An analysis of Clinical and Imaging Features
Authors: Ragel Brian T. , Osborn Anne G. , Whang Kum , Townsend Jeannette J. , Jensen Randy L. , Couldwell William T. 
Published: April 2006

AbstractOBJECTIVE:Subependymomas are slow-growing, benign tumors usually found incidentally in the fourth ventricle at autopsy. They are typically associated with the ventricular system and become apparent clinically only when symptoms of hydrocephalus or mass effect develop. We review clinical, histological, and contemporary radiographic presentations of 16 subependymomas, including 2 intraparenchymal tumors.METHODS:We retrospectively evaluated eight patients with pathologically proven subependymomas. Initial magnetic resonance imaging and magnetic resonance spectroscopy were reviewed when available. Imaging was also available on eight outside subependymoma cases reviewed by our radiology department.RESULTS:Twelve of these subependymomas were intraventricular, one was in the posterior fossa, two were intraparenchymal, and one was an intramedullary spinal cord tumor. These lesions were hypo- to hyperintense on T1- and T2-weighted magnetic resonance imaging, with minimal to moderate enhancement. Initial complaints included headache, seizures, tingling sensations, and weakness. Among our eight patients who underwent gross total resection with no adjuvant therapy, no recurrences have been noted on follow-up magnetic resonance imaging.CONCLUSION:Subependymomas are rare, representing only 0.51% of all central nervous system tumors operated on during an 8-year period at the University of Utah. Clinical symptoms were associated with tumor location: intracranial masses caused headaches, seizures, and neurological complaints, and spinal cord locations resulted in neurological deficit. The authors review the clinical presentation, management, and contemporary radiographic appearance of this rare tumor.
Lumbar Intramedullary Spinal Schistosomiasis Presenting as Progressive Paraparesis: Case Report
Authors: Kim Albert H. , Maher Cormac O. , Smith Edward R. 
Published: April 2006

Abstract

OBJECTIVE AND IMPORTANCE:
Blood fluke infection or schistosomiasis affects up to 300 million people worldwide. Although infection of the hepatic and urogenital systems commonly occurs, central nervous system involvement is rare. When presenting in the spinal cord, schistosomiasis can be difficult to diagnose because it can present as mass lesion or transverse myelitis. We describe a patient with lumbar intramedullary spinal schistosomiasis who presented to a tertiary medical center in the United States and discuss the diagnosis and treatment of this rare disease.

CLINICAL PRESENTATION:
A 25-year-old Brazilian man presented with progressive, subacute, bilateral lower extremity motor and sensory deficits and disturbances in bladder function. Magnetic resonance imaging revealed a diffusely enhancing mass expanding the region of the conus medullaris.

INTERVENTION:
Laboratory investigation disclosed serum and cerebrospinal fluid eosinophilia. Ultimately, cerebrospinal fluid serology demonstrated the presence of Schistosoma mansoni. The patient was treated with praziquantel and steroids and made a marked recovery.

CONCLUSION:
The clinical and radiographic manifestations of spinal schistosomiasis can mimic those of intra-axial spinal tumors and transverse myelitis. To avoid unnecessary surgery or delay in treatment, the clinician must have knowledge of this type of presentation. The increasing volume of international travel and high prevalence of the disease worldwide increases the possibility that the practicing neurosurgeon in the United States may encounter this rare but treatable disease.
Microwave-mediated Efficient Protection of Carbonyl Compounds as 1,3-Oxathiolanes in the Presence of Iodine under Solvent Free Condition
Authors: Bez Ghanashyam , Baruah Nabajyoti 
Published: April 2006

Abstract
A mild, efficient, and solvent free protocol for conversion of aldehydes and ketones into their corresponding 1,3-oxathiolanes using 2-mercaptoethanol in the presence of catalytic amount of elemental iodine is reported.
Some properties of continuous-state branching processes, with applications to Bartoszyński’s virus model
Authors: Pakes Anthony G. , Trajstman A. C. 
Published: April 2006

It is known that Bartoszyński’s model for the growth of rabies virus in an infected host is a continuous branching process. We show by explicit construction that any such process is a randomly time-transformed compound Poisson process having a negative linear drift.This connection is exploited to obtain limit theorems for the population size and for the jump times in the rabies model. Some of these results are obtained in a more general context wherein the compound Poisson process is replaced by a subordinator.
Discounted branching random walks
Authors: Athreya K. B. 
Published: April 2006

Let F(·) be a c.d.f. on [0,∞), f(s) = ∑∞0pjsi a p.g.f. with p0 = 0, < 1 < m = Σjpj < ∞ and 1 < ρ <∞. For the functional equation for a c.d.f. H(·) on [0,∞]

we establish that if 1 – F(x) = O(x–θ) for some θ > α =(log m)/(log p) there exists a unique solution H(·) to (∗) in the class C of c.d.f.’s satisfying 1 – H(x) = o(x–α).We give a probabilistic construction of this solution via branching random walks with discounting. We also show non-uniqueness if the condition 1 – H(x) = o(x–α) is relaxed.
State space expansions and the limiting behavior of quasi-birth-and-death processes
Authors: Beuerman Steven L. , Coyle Edward J. 
Published: April 2006

The notion of complete level crossing information, or LCI-completeness, is introduced for quasi-birth-death (QBD) processes. It is shown that state space expansions allow any QBD-process to be modified so that it is LCI-complete.For any LCI-complete, QBD-process, there exists a matrix W such that , where is the vector of limiting probabilities for all states on level n of the process. When W cannot be found in closed form, it can be found via an algorithm requiring fewer than m steps, where m is the number of states on each level of the process. The result of this algorithm is always a linear matrix equation for which W is the solution.In essentially all cases considered in this paper, the matrix W is a solution of the matrix quadraticX2A2 + XA1 + A0 = 0.Despite this fact, W is never equal to Neuts' rate matrix R, although the non-zero eigenvalues and the corresponding left eigenvectors of R are a subset of the eigenvalues and left eigenvectors of W. This fact leads to two methods for determining R from W.If the transition rates of the QBD-process are level-dependent, then it is also shown that matrices W(n) exist such that .
Stationary representation of queues. I
Authors: Szczotka Władysław 
Published: April 2006

The paper deals with the asymptotic behaviour of queues for which the generic sequence is not necessarily stationary but is asymptotically stationary in some sense. The latter property is defined by an appropriate type of convergence of probability distributions of the sequences to the distribution of a stationary sequence We consider six types of convergence of to The main result is as follows: if the sequence of the distributions converges in one of six ways then the sequence of distributions of the sequences converges in the same way, independently of initial conditions. Furthermore the limiting distribution is the same as the limiting distribution obtained by the weak convergence of the distributions Here wk and w∗k denote the waiting time of the kth unit in the queue generated by (v, u) and (v0, u0) respectively.
A new class of markov processes for image encoding
Authors: Barnsley Michael F. , Elton John H. 
Published: April 2006

A new class of iterated function systems is introduced, which allows for the computation of non-compactly supported invariant measures, which may represent, for example, greytone images of infinite extent. Conditions for the existence and attractiveness of invariant measures for this new class of randomly iterated maps, which are not necessarily contractions, in metric spaces such as , are established. Estimates for moments of these measures are obtained.Special conditions are given for existence of the invariant measure in the interesting case of affine maps on . For non-singular affine maps on , the support of the measure is shown to be an infinite interval, but Fourier transform analysis shows that the measure can be purely singular even though its distribution function is strictly increasing.
A multiclass feedback queue in heavy traffic
Authors: Reiman Martin I. 
Published: April 2006

We consider a single station queueing system with several customer classes. Each customer class has its own arrival process. The total service requirement of each customer is divided into a (possibly) random number of service quanta, where the distribution of each quantum may depend on the customer's class and the other quanta of that customer. The service discipline is round-robin, with random quanta.We prove a heavy traffic limit theorem for the above system which states that as the traffic intensity approaches unity, properly normalized sequences of queue length and sojourn time processes converge weakly to one-dimensional reflected Brownian motion.
Time-average optimal constrained semi-Markov decision processes
Authors: Beutler Frederick J. , Ross Keith W. 
Published: April 2006

Optimal causal policies maximizing the time-average reward over a semi-Markov decision process (SMDP), subject to a hard constraint on a time-average cost, are considered. Rewards and costs depend on the state and action, and contain running as well as switching components. It is supposed that the state space of the SMDP is finite, and the action space compact metric. The policy determines an action at each transition point of the SMDP.Under an accessibility hypothesis, several notions of time average are equivalent. A Lagrange multiplier formulation involving a dynamic programming equation is utilized to relate the constrained optimization to an unconstrained optimization parametrized by the multiplier. This approach leads to a proof for the existence of a semi-simple optimal constrained policy. That is, there is at most one state for which the action is randomized between two possibilities; at all other states, an action is uniquely chosen for each state. Affine forms for the rewards, costs and transition probabilities further reduce the optimal constrained policy to ‘almost bang-bang’ form, in which the optimal policy is not randomized, and is bang-bang except perhaps at one state. Under the same assumptions, one can alternatively find an optimal constrained policy that is strictly bang-bang, but may be randomized at one state. Application is made to flow control of a birth-and-death process (e.g., an M/M/s queue); under certain monotonicity restrictions on the reward and cost structure the preceding results apply, and in addition there is a simple acceptance region.
The single-server queue with independent GI/G and M/G input streams
Authors: Ott Teunis J. 
Published: April 2006

This paper studies the single-server queueing system with two independent input streams: a GI/G and an M/G stream. A new proof is given of an old result which shows how this system can be transformed into an equivalent ‘single input stream’ GI/G/1 queue, and methods to study that equivalent system numerically are given. As part of the numerical analysis, algorithms are given to compute the moments and the distribution function of busy periods in the M/G/1 queue, and of other related busy periods. Special attention is given to the single-server queue with independent D/G and M/G input streams.This work is to be used in the modeling of real-time computer systems, which can often be described as a single-server queueing system with independent D/G and M/G input streams, see for example Ott (1984b).
Teletraffic engineering for product-form circuit-switched networks
Authors: Ross Keith W. , Tsang Danny 
Published: April 2006

We develop a performance modeling methodology for product-form circuit-switched networks. These networks allow for: arbitrary topology and link capacities; Poisson and finite population arrivals; multiple classes of calls, each class with a different route and bandwidth requirement; conference as well as point-to-point calls. The methodology is first applied togeneralized tree networks, which consist of multiple access links feeding into a common link. Each access link may support multiple ‘long-distance' classes (requiring circuits only on the access link and on the common link) and multiple ‘local' classes (requiring circuits only on the access link). For generalized tree networks an efficient algorithm is given to determine the blocking probabilities. The methodology is then applied tohierarchical tree networks, where traffic is repeatedly merged in the direction of a root node.We also establish a ‘Norton' theorem for product-form circuit-switched networks. This theorem implies that for any given calling class, the entire network can be replaced by an Erlang loss system with a state-dependent arrival rate, without modifying the equilibrium probabilities for the particular calling class.
Scheduling and stability aspects of a general class of parallel processing systems
Authors: Bambos Nicholas , Walrand Jean 
Published: April 2006

In this paper we study the following general class of concurrent processing systems. There are several different classes of processors (servers) and many identical processors within each class. There is also a continuous random flow of jobs, arriving for processing at the system. Each job needs to engage concurrently several processors from various classes in order to be processed. After acquiring the needed processors the job begins to be executed. Processing is done non-preemptively, lasts for a random amount of time, and then all the processors are released simultaneously. Each job is specified by its arrival time, its processing time, and the list of processors that it needs to access simultaneously. The random flow (sequence) of jobs has a stationary and ergodic structure. There are several possible policies for scheduling the jobs on the processors for execution; it is up to the system designer to choose the scheduling policy to achieve certain objectives.We focus on the effect that the choice of scheduling policy has on the asymptotic behavior of the system at large times and especially on its stability, under general stationary and ergocic input flows.
Subgeometric Rates of Convergence of f-Ergodic Markov Chains
Authors: Tuominen Pekka , Tweedie Richard L. 
Published: April 2006

Let Φ = {Φ n} be an aperiodic, positive recurrent Markov chain on a general state space, π its invariant probability measure and f ≧ 1. We consider the rate of (uniform) convergence of Ex[g(Φ n)] to the stationary limit π (g) for |g| ≦ f: specifically, we find conditions under which as n →∞, for suitable subgeometric rate functions r. We give sufficient conditions for this convergence to hold in terms of(i) the existence of suitably regular sets, i.e. sets on which (f, r)-modulated hitting time moments are bounded, and(ii) the existence of (f, r)-modulated drift conditions (Foster–Lyapunov conditions).The results are illustrated for random walks and for more general state space models.
A note on the first emptiness time of an infinite reservoir with inputs forming a Markov chain
Authors: Lehoczky J. P. 
Published: April 2006

SummaryThe first emptiness time of an infinite reservoir with unit release and discrete input forming a stationary. Markov chain is investigated. The exact distribution of the first emptiness time is derived without the use of moment generating functions. The first and second moments of this distribution are given explicity. The close relationship between the process with stationary independent input and Markov chain input is emphasized.The first moment of the area beneath the sample path up to first emptiness is computed. This area is often used as a measure of total delay in traffic flow theory.