bluuebunny/crossref_metadata_2025 huggingface dataset:
Neurons in Monkey Prefrontal Cortex Whose Activity Tracks the Progress of a Three-Step Self-Ordered Task
Authors: Hasegawa Ryohei P. , Blitz Ari M. , Goldberg Michael E.
Published: May 2004

The self-ordered task is a powerful tool for the analysis of dorsal prefrontal deficits. Each trial consists of a number of steps, and subjects must remember their choices in previous steps. The task becomes more difficult as the number of objects to be remembered increases. We recorded the activity of 156 neurons in the mid-dorsal prefrontal cortex of two rhesus monkeys performing an oculomotor version of the task. Although the task requires working memory, there was no convincing evidence for activity selective for the working memory of the objects that the monkey had to remember. Instead, nearly one-half of neurons (47%, 74/156) showed activity that was modulated according to the step of the task in any one or more task periods. Although the monkey's reward also increased with step, the neurons exhibited little or no step modulation in a reward control task in which reward increased without a concurrent increase in task difficulty. The activity of some neurons was also selective for the location of saccade target that the monkey voluntarily chose. Neurons showed less step modulation in error trials, and there was no increase between the second and third step responses on trials in which the error was on the third step. These results suggest that the mid-dorsal prefrontal cortex contributes to the self-ordered task, not by providing an object working memory signal, but by regulating some general aspect of the performance in the difficult task.
Fructose-responsive genes in the small intestine of neonatal rats
Authors: Cui Xue-Lin , Soteropoulos Patricia , Tolias Peter , Ferraris Ronaldo P.
Published: May 2004

The intestinal brush border fructose transporter GLUT5 (SLC2A5) typically appears in rats after weaning is completed. However, precocious consumption of dietary fructose or in vivo perfusion for 4 h of the small intestine with high fructose (HF) specifically stimulates de novo synthesis of GLUT5 mRNA and protein before weaning is completed. Intermediary signals linking the substrate, fructose, to GLUT5 transcription are not known but should also respond to fructose perfusion. Hence, we used microarray hybridization and RT-PCR to identify genes whose expression levels change during HF relative to high-glucose (HG) perfusion. Expression of GLUT5 and NaPi2b, the intestinal Na+-dependent phosphate transporter, dramatically increased and decreased, respectively, with HF perfusion for 4 h. Expression of >20 genes, including two key gluconeogenic enzymes, glucose-6-phosphatase (G6P) and fructose-1,6-bisphosphatase, also increased markedly, along with fructose-2,6-bisphosphatase, an enzyme unique to fructose metabolism and regulating fructose-1,6-bisphosphatase activity. GLUT5 and G6P mRNA abundance, which increased dramatically with HF relative to HG, α-methylglucose, and normal Ringer perfusion, may be tightly and specifically linked to changes in intestinal luminal fructose but not glucose concentrations. G6P but not GLUT5 mRNA abundance increased after just 20 min of HF perfusion. This cluster of gluconeogenic enzymes and their common metabolic intermediate fructose-6-phosphate may regulate fructose metabolism and GLUT5 expression in the small intestine.
Race-Specific Differences in Endothelial Function
Authors: Kalinowski Leszek , Dobrucki Iwona T. , Malinski Tadeusz
Published: May 2004

Background—

The prevalence of the endothelium-impaired function disorders, such as hypertension and diabetes mellitus, and the severity of their complications are considerably greater in blacks than whites. Evidence has accumulated that superoxide (O
2
−
) production and its interaction with nitric oxide (NO), yielding the strong oxidant peroxynitrite (ONOO
−
), play central roles in vascular pathophysiology. We hypothesized that the differences in endothelial NO/O
2
−
/ONOO
−
metabolism may highlight the potential predisposition to endothelial dysfunction and cardiovascular complications prevalent in blacks.

Methods and Results—

Highly sensitive tandem electrochemical NO/O
2
−
/ONOO
−
nanosensors were positioned in single human umbilical vein endothelial cells (HUVECs) isolated from blacks and whites, and the kinetics of NO/O
2
−
/ONOO
−
release were recorded in vitro. HUVECs were also analyzed by Western immunoblotting and enzyme activity assays for NAD(P)H-oxidase and endothelial NO synthase (eNOS). Compared with whites, HUVECs from blacks elicited reduced release of bioactive NO with an accompanying increase in the release of both O
2
−
and ONOO
−
. The greater potency of NO production because of eNOS upregulation in HUVECs from blacks is associated with a decrease in the NO bioavailability. This is due to increased NO degradation by excess O
2
−
produced primarily by 2 enzymatic sources: NAD(P)H-oxidase and uncoupled eNOS.

Conclusions—

Compared with whites, the steady-state NO/O
2
−
/ONOO
−
balance in endothelial cells from blacks is kept closer to the redox states characteristic for the endothelium-impaired function disorders. This may explain the differences in racial predisposition to the endothelium dysfunction during ongoing vascular disturbances with the hallmark of enhanced NO inactivation within the endothelium by oxidative stress.
Ultrasound Microbubble Destruction Imaging in Acute Middle Cerebral Artery Stroke
Authors: Kern Rolf , Perren Fabienne , Schoeneberger Katrin , Gass Achim , Hennerici Michael , Meairs Stephen
Published: May 2004

Background and Purpose—

Cerebral perfusion imaging in acute stroke assists in determining the subtype and the severity of ischemia. Recent studies in perfusion models and in healthy volunteers have shown that ultrasound perfusion imaging based on microbubble destruction can be used to assess tissue perfusion. We applied ultrasound microbubble destruction imaging (MDI) to identify perfusion deficits in patients with acute middle cerebral artery (MCA) territory stroke.

Methods—

Fifteen acute MCA stroke patients with sufficient transtemporal bone windows were investigated with ultrasound MDI and perfusion-weighted MRI (PWI). MDI was performed using power pulse-inversion contrast harmonic imaging. Thirty seconds after a bolus injection of the echo contrast agent SonoVue, microbubbles were destroyed using a series of high-energy pulses. Local perfusion status was analyzed in selected regions of interest by destruction curves and acoustic intensity differences (ΔI) before and after microbubble destruction. Local perfusion status was then compared with perfusion compromise as identified on PWI.

Results—

The mean differences of acoustic intensity from the ischemic MCA territory were significantly diminished compared with the normal hemisphere (ΔI=2.52±1.75 versus ΔI=13.79±7.31;
P
<0.001), resulting in lower slopes of microbubble destruction. PWI confirmed perfusion changes in the selected anatomical regions on time-to-peak maps in all 15 patients.

Conclusions—

MDI is a qualitative method that can rapidly detect perfusion changes in acute stroke. When combined with other ultrasound techniques and PWI, it may well be valuable in the care of stroke unit patients, eg, as a screening method and for follow-up assessments of perfusion deficits.
The Biomechanical Effects of Low-Dose Irradiation on Bone-Patellar Tendon-Bone Allografts
Authors: Curran Andrew R. , Adams Douglas J. , Gill Julie L. , Steiner Mark E. , Scheller Arnold D.
Published: May 2004

Background

Despite evidence that low-dose irradiation of 2 Mrad (20 kGy) is not virucidal for patellar tendon allografts and reduces tissue strength, many tissue bank protocols include low-dose irradiation.

Hypothesis

Maintaining tissue mechanical integrity may be particularly relevant toward accelerated rehabilitation of the injured knee, where the cyclic function of patellar tendon allografts is critical.

Study Design

Controlled laboratory study.

Methods

The cyclic and failure mechanical properties of paired bone-patellar tendon-bone allografts, with and without current low-dose irradiation of 20 kGy, were evaluated. Specimens were loaded from 50 N to 250 N for 1000 cycles at 0.5 Hz and subsequently loaded to failure at a strain rate of 100% per second.

Results

After 1000 cycles, grafts elongated 27% more when irradiated than when not (4.4 ± 1.5 mm vs 3.4 ± 1.0 mm; P = .03). Failure load averaged 1965 ± 512 N for irradiated grafts and 2457 ± 647 N for nonirradiated grafts (P = .007).

Conclusions

The diminished strength of irradiated grafts may contribute to overt anterior cruciate ligament graft failure, and the increase in cyclic elongation may also be detrimental to graft function.

Clinical Relevance

These results suggest that one should consider the use of nonirradiated allografts as an alternative to irradiated grafts in anterior cruciate ligament reconstruction.
Results of Transphyseal Anterior Cruciate Ligament Reconstruction Using Patellar Tendon Autograft in Tanner Stage 3 or 4 Adolescents with Clearly Open Growth Plates
Authors: Shelbourne K. Donald , Gray Tinker , Wiley Bryan V.
Published: May 2004

Background

Drilling across the physes for intra-articular anterior cruciate ligament reconstruction is considered risky for skeletally immature patients.

Hypothesis

Skeletally immature patients with clearly open growth plates can safely undergo intra-articular anterior cruciate ligament reconstruction with patellar tendon autograft without suffering growth plate disturbance.

Study Design

Retrospective review of prospectively collected data.

Methods

Surgery involved drilling tunnels through the tibial and femoral physes, the bone plugs were placed proximal to the physes, and button fixation was placed on the cortex. Of 272 skeletally immature patients, 16 had clearly open growth plates. Tanner stage of physical development was evaluated. Follow-up evaluation included objective and subjective data.

Results

At the time of surgery, 7 patients were Tanner stage 3 and 9 were Tanner stage 4. Clinical follow-up (mean, 3.4 years after surgery) showed that the mean growth after surgery was 11.7 ± 4.2 cm for boys and 6.6 ± 2.3 cm for girls. No patients had growth plate disturbances, gross leg deformities, or gross leg-length discrepancies. Subjective results (mean, 5.6 years after surgery) showed a mean total score of 97.6 ± 2.9 for the modified Noyes survey and 95.4 ± 6.9 for the International Knee Documentation Committee survey. All patients returned to competitive sports after surgery.

Conclusion

In 16 skeletally immature patients with clearly open growth plates who were Tanner stage 3 or 4, an intra-articular anterior cruciate ligament reconstruction was performed using a patellar tendon autograft with no gross growth disturbance; however, the surgical technique was meticulous for placing the bone plugs proximal to the physes, and the graft was not overtensioned.
Primary Repair of Posterior Cruciate Ligament Avulsion Fracture
Authors: Inoue Masayuki , Yasuda Kazunori , Kondo Eiji , Saito Katsutoshi , Ishibe Motomi
Published: May 2004

Background

In the posterior cruciate ligament avulsion fracture, posterior instability cannot be completely restored by the anatomical reduction and fixation of an avulsed fragment.

Hypothesis

The occult midsubstance injury inside the posterior cruciate ligament may affect the residual posterior instability after anatomical reduction and internal fixation of the avulsed fragment.

Study Design

Prospective comparative clinical study.

Methods

Thirty-one patients were followed for a period of 2 to 8 years. Based on magnetic resonance images taken immediately after the injury, these patients were divided into 2 groups, the occult injury group (group O, 15 knees) and the uninjured group (group N, 16 knees).

Results

The side-to-side difference of the posterior knee instability was 3.2 mm in group O and 3.0 mm in group N. Approximately 60% of the knees examined showed mild posterior instability in both groups. There were no significant differences found between the 2 groups.

Conclusion

The occult posterior cruciate ligament midsubstance injury does not significantly affect postoperative posterior instability of the knee. This fact did not support the hypothesis that has been commonly considered thus far.

Clinical Relevance

It is not necessary for orthopaedic surgeons to be overly apprehensive about occult midsubstance injury in the treatment of posterior cruciate ligament avulsion fracture.
Active Patellar Tracking Measurement
Authors: Shih Yi-Fen , Bull Anthony M.J. , McGregor Alison H. , Amis Andrew A.
Published: May 2004

Background

Many patients suffer patellar instability that may relate to transient patellar tracking abnormalities.

Objective

To develop and test a technique to measure dynamic patellar tracking.

Study Design

Controlled laboratory and in vivo study.

Method

A functional knee brace was modified to allow an ultrasound transducer to be mounted laterally to the femur, following the path of the patella during knee movement. An ultrasound system was used to measure patellar mediolateral position parallel to the femoral transepicondylar axis. Ten subjects with no patellar instability were studied to obtain patellar tracking and accuracy data.

Results

The interobserver and intraobserver reproducibility ranged from 0.2 ± 0.1 mm to 1.0 ± 0.5 mm. The accuracy of the ultrasound measurement was checked against magnetic resonance imaging and was 0.6 ± 1.9 mm. The patella moved medially then laterally from extension to flexion when sitting. Squatting and stepping produced a more lateral path, without the initial medial translation. The patella was more lateral during knee extension than during flexion.

Conclusions

This novel method for measurement of dynamic patellar mediolateral tracking was found to have good intraobserver and interobserver reproducibility, and the measurements matched closely with those obtained from magnetic resonance imaging reconstructions of static patellar positions. Some preliminary data for tracking in 3 activities were obtained from 10 normal knees.
HTLV-I Tax induces a novel interaction between p65/RelA and p53 that results in inhibition of p53 transcriptional activity
Authors: Jeong Soo-Jin , Radonovich Michael , Brady John N. , Pise-Masison Cynthia A.
Published: May 2004

Nuclear factor κB (NF-κB) activation plays a critical role in oncogenesis by human T-cell lymphotrophic virus type I (HTLV-I), the etiologic agent of adult T-cell leukemia (ATL), and is indispensable for maintenance of the malignant phenotype. In T lymphocytes, Tax-mediated p53 inhibition is dependent on Tax activation of the NF-κB pathway and is linked to p53 phosphorylation. We now report that blocking NF-κB transcriptional activation in HTLV-I–transformed cells restores p53 activity. Further, using mouse embryo fibroblast (MEF) null cells and antisense oligonucleotides to inhibit expression of NF-κB family members, we demonstrate that the p65 subunit of NF-κB is uniquely involved in p53 inhibition. Coimmunoprecipitation assays demonstrate an interaction between p65 and p53 in HTLV-I–transformed cells. In transient transfection assays, we demonstrate that Tax induces the p53-p65 interaction. Phosphorylation of p53 at serines 15 and 392 is critical for complex formation. Importantly, Tax-mediated p53 inhibition correlates with p65 and p53 interaction. By using chromatin immunoprecipitation (ChIP) assays, we find that in HTLV-I–transformed cells p53 and p65 form a complex on the inactive, p53-responsive murine double minute 2 (MDM2) promoter. Consistent with reduced transcriptional activity, transcription factor IID (TFIID) binding is not observed. These studies identify a unique mechanism for p53 regulation by the p65/RelA subunit of NF-κB.
A class of complete benchmark models with intensity-based jumps
Authors: Platen Eckhard
Published: May 2004

This paper proposes a class of complete financial market models, the benchmark models, with security price processes that exhibit intensity-based jumps. The benchmark or reference unit is chosen to be the growth-optimal portfolio. Primary security account prices, when expressed in units of the benchmark, turn out to be local martingales. In the proposed framework an equivalent risk-neutral measure need not exist. Benchmarked fair derivative prices are obtained as conditional expectations of future benchmarked prices under the real-world probability measure. This concept of fair pricing generalizes the classical risk-neutral approach and the actuarial present-value pricing methodology.
The almost sure central limit theorem for one-dimensional nearest-neighbour random walks in a space-time random environment
Authors: Bérard Jean
Published: May 2004

The central limit theorem for random walks on ℤ in an i.i.d. space-time random environment was proved by Bernabeiet al.for almost all realization of the environment, under a small randomness assumption. In this paper, we prove that, in the nearest-neighbour case, when the averaged random walk is symmetric, the almost sure central limit theorem holds for anarbitrarylevel of randomness.
Sequential selection of random vectors under a sum constraint
Authors: Stanke Mario
Published: May 2004

We observe a sequence X1, X2,…, Xn of independent and identically distributed coordinatewise nonnegative d-dimensional random vectors. When a vector is observed it can either be selected or rejected but once made this decision is final. In each coordinate the sum of the selected vectors must not exceed a given constant. The problem is to find a selection policy that maximizes the expected number of selected vectors. For a general absolutely continuous distribution of the Xi we determine the maximal expected number of selected vectors asymptotically and give a selection policy which asymptotically achieves optimality. This problem raises a question closely related to the following problem. Given an absolutely continuous measure μ on Q = [0,1]d and a τ ∈ Q, find a set A of maximal measure μ(A) among all A ⊂ Q whose center of gravity lies below τ in all coordinates. We will show that a simplicial section {x ∈ Q | 〈x, θ〉 ≤ 1}, where θ ∈ ℝd, θ ≥ 0, satisfies a certain additional property, is a solution to this problem.
Backward SDEs with two barriers and continuous coefficient: an existence result
Authors: Lepeltier Jean-Pierre , San Martín Jaime
Published: May 2004

In this work we prove the existence of a solution for a doubly reflected backward SDE with a continuous linearly increasing coefficient in the case where the barriers L and U are such that L < U on [0,T) and there exists a continuous semimartingale between L and U.
Large deviations for super-Brownian motion with immigration
Authors: Zhang Mei
Published: May 2004

We derive a large-deviation principle for super-Brownian motion with immigration, where the immigration is governed by the Lebesgue measure. We show that the speed function is t1/2 for d = 1, t/logt for d = 2 and t for d ≥ 3, which is different from that of the occupation-time process counterpart (without immigration) and the model of random immigration.
On-line parameter estimation for a failure-prone system subject to condition monitoring
Authors: Lin Daming , Makis Viliam
Published: May 2004

In this paper, we study the on-line parameter estimation problem for a partially observable system subject to deterioration and random failure. The state of the system evolves according to a continuous-time homogeneous Markov process with a finite state space. The state of the system is hidden except for the failure state. When the system is operating, only the information obtained by condition monitoring, which is related to the working state of the system, is available. The condition monitoring observations are assumed to be in continuous range, so that no discretization is required. A recursive maximum likelihood (RML) algorithm is proposed for the on-line parameter estimation of the model. The new RML algorithm proposed in the paper is superior to other RML algorithms in the literature in that no projection is needed and no calculation of the gradient on the surface of the constraint manifolds is required. A numerical example is provided to illustrate the algorithm.
On the distribution of the search cost for the move-to-front rule with random weights
Authors: Barrera Javiera , Paroissin Christian
Published: May 2004

Consider a countable list of files updated according to the move-to-front rule. Files have independent random weights, which are used to construct request probabilities. Exact and asymptotic formulae for the Laplace transform of the stationary search cost are given for i.i.d. weights. Similar expressions are derived for the first two moments. Some results are extended to the case of independent weights.
On the rate of Poisson process approximation to a Bernoulli process
Authors: Ruzankin P. S.
Published: May 2004

The main result of the paper is a refinement of Xia's (1997) bound on the Kantorovich distance between distributions of a Bernoulli point process and an approximating Poisson process. In particular, we show that the distance between distributions of a Bernoulli point process and the Poisson process with the same mean measure has the order of the total variation distance between the laws of the total masses of these processes.
A note on the waiting time in M[X]/G/1 queueing systems with a removable server
Authors: Loris-Teghem Jacqueline
Published: May 2004

For the M[X]/G/1 queueing model with a general exhaustive-service vacation policy, it has been proved that the Laplace-Stieltjes transform (LST) of the steady-state distribution function of the waiting time of a customer arriving while the server is active is the product of the corresponding LST in the bulk arrival model with unremovable server and another LST. The expression given for the latter, however, is valid only under the assumption that the number of groups arriving in an inactive phase is independent of the sizes of the groups. We here give an expression which holds in the general case. For the N-policy case, we also give an expression for the LST of the steady-state distribution function of the waiting time of a customer arriving while the server is inactive.
Estimation for discretely observed diffusions using transform functions
Authors: Kelly Leah , Platen Eckhard , Sørensen Michael
Published: May 2004

This paper introduces a new estimation technique for discretely observed diffusion processes. Transform functions are applied to transform the data to obtain good and easily calculated estimators of both the drift and diffusion coefficients. Consistency and asymptotic normality of the resulting estimators is investigated. Power transforms are used to estimate the parameters of affine diffusions, for which explicit estimators are obtained.
Restricted quasi-score estimating functions for sample survey data
Authors: Lin Y.-X. , Steel D. , Chambers R. L
Published: May 2004

This paper applies the theory of the quasi-likelihood method to model-based inference for sample surveys. Currently, much of the theory related to sample surveys is based on the theory of maximum likelihood. The maximum likelihood approach is available only when the full probability structure of the survey data is known. However, this knowledge is rarely available in practice. Based on central limit theory, statisticians are often willing to accept the assumption that data have, say, a normal probability structure. However, such an assumption may not be reasonable in many situations in which sample surveys are used. We establish a framework for sample surveys which is less dependent on the exact underlying probability structure using the quasi-likelihood method.
Fitting the variance-gamma model to financial data
Authors: Seneta Eugene
Published: May 2004

This paper has as its main theme the fitting in practice of the variance-gamma distribution, which allows for skewness, by moment methods. This fitting procedure allows for possible dependence of increments in log returns, while retaining their stationarity. It is intended as a step in a partial synthesis of some ideas of Madan, Carr and Chang (1998) and of Heyde (1999). Standard estimation and hypothesis-testing theory depends on a large sample of observations which are independently as well as identically distributed and consequently may give inappropriate conclusions in the presence of dependence.
Extremal problems for regenerative phenomena
Authors: Kingman J. F. C.
Published: May 2004

This paper explores the possibility of a calculus of variations powerful enough to prove inequalities for the p-functions of regenerative phenomena such as that conjectured by Davidson and proved by Dai. It is shown that this is unlikely to be achieved by compactifying the space of standard p-functions, and a more promising approach is that of working in a compact subspace. The analysis leads to a class of candidate p-functions which contains all the maxima of general functionals.
Averaging analysis of a point process adaptive algorithm
Authors: Solo Victor
Published: May 2004

Motivated by a problem in neural encoding, we introduce an adaptive (or real-time) parameter estimation algorithm driven by a counting process. Despite the long history of adaptive algorithms, this kind of algorithm is relatively new. We develop a finite-time averaging analysis which is nonstandard partly because of the point process setting and partly because we have sought to avoid requiring mixing conditions. This is significant since mixing conditions often place restrictive history-dependent requirements on algorithm convergence.
A revenue-equivalence theorem for electricity auctions
Authors: Hinz Juri
Published: May 2004

The purpose of this paper is to analyse the real-time trading of electricity. We address a model for an auction-like trading which captures key features of real-world electricity markets. Our main result establishes that, under certain conditions, the expected total payment for electricity is independent of the particular auction type. This result is analogous to the revenue-equivalence theorem known for classical auctions and could contribute to an improved understanding of different electricity market designs and their comparison.
Limit theorem for continuous-time random walks with two time scales
Authors: Becker-Kern Peter , Meerschaert Mark M. , Scheffler Hans-Peter
Published: May 2004

Continuous-time random walks incorporate a random waiting time between random jumps. They are used in physics to model particle motion. A physically realistic rescaling uses two different time scales for the mean waiting time and the deviation from the mean. This paper derives the scaling limits for such processes. These limit processes are governed by fractional partial differential equations that may be useful in physics. A transfer theorem for weak convergence of finite-dimensional distributions of stochastic processes is also obtained.
The marriage of statistics and seismology
Authors: Vere-Jones David
Published: May 2004

Daryl Daley has kindly invited me to write some prefatory words, autobiographical in character, to the collection of articles which follows. I am very happy to do this, but first let me express my appreciation of the efforts which Daryl, Peter Thomson, and the contributors have put into the making of this volume. It is a wonderful tribute, which I greatly appreciate. May I also take the opportunity to acknowledge the help of all of those colleagues, whether or not they have contributed directly to this volume, whose support, professional advice, knowledge, competence and companionship have made my years as statistician and tyro seismologist extremely rewarding. To all such, a big thank you.
David Vere-Jones's influence on statistical education
Authors: Phillips Brian
Published: May 2004

David Vere-Jones's interest in mathematical and statistical education was triggered in the early 1960s during his visits to Russia when he met leading mathematicians who were deeply involved in these areas as well as in their own research. Through the 1970s and 1980s David's involvement in education grew in New Zealand where he became influential in the developments in mathematics and statistics teaching, especially at school level. By the early 1990s he had become very involved in the Education Committee of the International Statistical Institute (ISI) and had a key role in the Third International Conference on Teaching Statistics (ICOTS-3) in Dunedin, 1990. This was soon followed by the pivotal role he played in the establishment of the International Association for Statistical Education (IASE). This paper describes the formative influences underlying David's involvement in statistical education and his influence on the growth of the IASE.
The moment index of minima
Authors: Daley D. J.
Published: May 2004

For a random variable (RV) X its moment index κ(X) ≡ sup{κ : E(|X|κ) < ∞} lies in 0 ≤ κ (X) ≤∞; it is a critical quantity and finite for heavy-tailed RVs. The paper shows that κ (min(X, Y)) ≥ κ(X) + κ (Y) for independent non-negative RVs X and Y. For independent non-negative ‘excess' RVs Xs and Ys whose distributions are the integrated tails of X and Y, κ (X) + κ (Y) ≤ κ (min(Xs, Ys)) + 2 ≤ κ (min(X, Y)). An example shows that the inequalities can be strict, though not if the tail of the distribution of either X or Y is a regularly varying function.
Misspecified change-point estimation problem for a Poisson process
Authors: Dabye Ali S. , Kutoyants Yury A.
Published: May 2004

Consider an inhomogeneous Poisson process X on [0, T] whose unknown intensity function ‘switches' from a lower function g∗ to an upper function h∗ at some unknown point θ∗. What is known are continuous bounding functions g and h such that g∗(t) ≤ g(t) ≤ h(t) ≤ h∗(t) for 0 ≤ t ≤ T. It is shown that on the basis of n observations of the process X the maximum likelihood estimate of θ∗ is consistent for n →∞, and also that converges in law and in pth moment to limits described in terms of the unknown functions g∗ and h∗.
An evaluation of Chinese annual earthquake predictions, 1990–1998
Authors: Shi Yaolin , Liu Jie , Zhang Guomin
Published: May 2004

The annual earthquake predictions of the China Seismological Bureau (CSB) are evaluated by means of anRscore (anRscore is approximately 0 for completely random guesses, and approximately 1 for completely successful predictions). The averageRscore of the annual predictions in China in the period 1990–1998 is about 0.184, significantly larger than 0.0. However, background seismicity is higher in seismically active regions. If a ‘random guess' prediction is chosen to be proportional to the background seismicity, the expectedRscore is 0.123, and the nine-year meanRscore of 0.184 as observed is only marginally higher than this background value. Monte Carlo tests indicate that the probability of attaining anRscore ofactual prediction by background seismicity based on random guessis about. It is concluded that earthquake prediction in China is still in a very preliminary stage, barely above a pure chance level.
nemo-like kinaseis an essential co-activator of Wnt signaling during early zebrafish development
Authors: Thorpe Chris J. , Moon Randall T.
Published: May 2004

Wnt/β-catenin signaling regulates many aspects of early vertebrate development, including patterning of the mesoderm and neurectoderm during gastrulation. In zebrafish, Wnt signaling overcomes basal repression in the prospective caudal neurectoderm by Tcf homologs that act as inhibitors of Wnt target genes. The vertebrate homolog of Drosophila nemo, nemo-like kinase (Nlk), can phosphorylate Tcf/Lef proteins and inhibit the DNA-binding ability of β-catenin/Tcf complexes, thereby blocking activation of Wnt targets. By contrast, mutations in a C. eleganshomolog show that Nlk is required to activate Wnt targets that are constitutively repressed by Tcf. We show that overexpressed zebrafish nlk, in concert with wnt8, can downregulate two tcf3 homologs, tcf3a and tcf3b, that repress Wnt targets during neurectodermal patterning. Inhibition of nlk using morpholino oligos reveals essential roles in regulating ventrolateral mesoderm formation in conjunction with wnt8, and in patterning of the midbrain, possibly functioning with wnt8b. In both instances, nlk appears to function as a positive regulator of Wnt signaling. Additionally, nlk strongly enhances convergent/extension phenotypes associated with wnt11/silberblick, suggesting a role in modulating cell movements as well as cell fate.
Dynamic changes in traction forces with DC electric field in osteoblast-like cells
Authors: Curtze Sami , Dembo Micah , Miron Miguel , Jones David B.
Published: May 2004

Primary bovine osteoblasts and human osteosarcoma cells exposed to direct-current electric fields undergo processes of retraction and elongation ultimately resulting in the realignment of the long cellular axis perpendicular to the electric field. The time taken for this reorientation was inversely correlated to field strength within a certain range. Cellular force output during reorientation was analyzed using a simple modification of traction force microscopy. The first detectable reaction was an increase in average traction force magnitude occurring between 10 and 30 seconds of electric field exposure. In the following 2 to 15 minutes traction forces at margins tangential to the electric field decreased below their initial values. Phase-contrast microscopy revealed elongating protrusions at these margins several minutes later. We could not correlate the initial traction changes with any change in intracellular free calcium levels measured using the fluorescent dye Fura-2 AM.
Dyslipidemias and HMG-CoA Reductase Inhibitor Prescription in Heart Transplant Recipients
Authors: de Denus Simon , Al-Jazairi Abdulrazaq , Loh Evan , Jessup Mariell , Stanek Eric J , Spinler Sarah A
Published: May 2004

BACKGROUND:

The treatment of dyslipidemias in orthotopic heart transplant (OHT) recipients is not highlighted in the National Cholesterol Education Program Adult Treatment Panel guidelines. Emerging data suggest that hydroxymethylglutaryl-coenzyme A reductase inhibitors (statins) safely reduce the risk of transplant rejection and coronary artery vasculopathy in OHT patients.

OBJECTIVE:

To assess the proportion of patients from our institution reaching the low-density lipoprotein cholesterol (LDL-C) target of <100 mg/dL, evaluate the impact of statins in reaching this goal, and evaluate the prescribing practice for statins in US OHT centers.

METHODS:

The management of dyslipidemia of OHT recipients followed at our institution was retrospectively evaluated. In addition, the use of statins in adult OHT centers in the US that performed ≥1 5 OHTs per year was assessed through a survey.

RESULTS:

Of the 328 patients from our institution, 58.5% achieved an LDL-C <100 mg/dL. Patients prescribed statins were more likely to reach this goal (p < 0.01). A total of 85.0% of centers responding to the survey use statins as a part of their post-OHT protocol, primarily to reduce coronary artery vasculopathy (70.6%).

CONCLUSIONS:

Due to the potential for improved outcomes, a large proportion of patients are prescribed a statin. Our results support previous findings that statins are safe and effective in reducing LDL-C in the management of dyslipidemias in OHT recipients. Nonetheless, dyslipidemias are suboptimally managed in many post-OHT patients.
The construction of awareness in early‐stage Alzheimer's disease: A review of concepts and models
Authors: Clare Linda
Published: May 2004

Objectives: This review considers the concepts and models that, often implicitly, underlie accounts and studies of variations in awareness of difficulties in people with early‐stage Alzheimer's disease (AD). In order to do this, it is necessary to draw on explanations presented within the discourses of different disciplines. The review aims to explore the key tensions and debates that arise in attempting to conceptualize awareness, and attempts to specify what kind of conceptual framework is needed in order to advance our understanding of variations in awareness in AD.

Methods: A range of literature relating to concepts and models of awareness, drawn from different disciplines and published during the past 30 years, is critically reviewed.

Results: The literatures of different disciplines present varying constructions of the concept of awareness. Neuropsychological, psychiatric and psychosocial explanations are considered and their relevance to understanding awareness in early‐stage AD is discussed.

Conclusions: An understanding of variations in awareness in early‐stage AD requires a biopsychosocial model of awareness that incorporates the influence of both neuropsychological impairments and psychosocial responses. Improved understanding of variations in awareness is essential for the development of person‐centred approaches to intervention and care in AD.
Monitoring cognitive changes: Psychometric properties of six cognitive tests
Authors: Bird Chris M. , Papadopoulou Kyriaki , Ricciardelli Paola , Rossor Martin N. , Cipolotti Lisa
Published: May 2004

Objectives: Repeated neuropsychological assessments are often used to monitor change in cognitive functioning over time. Thus, knowledge about the reliability and stability of neuropsychological tests and the effects of age and IQ is of paramount importance. In this study we document, for six cognitive tests: test‐retest reliabilities, practice effects, reliable change (RC) indices corrected for practice, and the impact of premorbid IQ and age.

Design: A sample of 188 normal adults (aged 40‐70 years) were administered, on two occasions, one or more of the following tests: the Graded Naming Test (GNT), the Silhouettes Test, two tests of verbal fluency, the Modified Wisconsin Card Sorting Test, and a new test of speed and attention (the Symbol Digit Test). There was a 1‐month interval between assessments. At first assessment, all participants were administered the revised National Adult Reading Test (NART).

Results: The test‐retest reliability of the tests ranged from very good (the GNT and Silhouettes Test) to moderate (verbal fluency tests and Symbol Digit Test) and to poor (Modified Card Sorting Test). Significant, although modest, practice effects were found on all tests. RC indices were generally large except for the Graded Naming Test and the Silhouettes Test. Premorbid IQ scores significantly correlated with performance on all the tests, the exception being semantic fluency. Age only correlated with the Silhouettes Test and the new Symbol Digit Test. Neither NART IQ nor age correlated with practice effects.

Conclusion: The psychometric properties of the GNT and Silhouettes Test indicated that they are useful tools for monitoring even small cognitive changes. In contrast, the verbal fluency tests and the new Symbol Digit Test are only suitable for monitoring large changes in performance. The Modified Card Sorting Test is an unreliable tool for monitoring ‘executive’ functions.
Reduced negative priming in schizotypy: Failure to replicate
Authors: Moritz Steffen , Andresen Burghard
Published: May 2004

Objective: The aim of the present study was to investigate the association of negative priming and schizotypal personality using a Stroop‐version of the paradigm.

Methods: Negative priming was determined for 160 healthy participants. Schizotypal symptoms were assessed with several schizotypal scales.

Results: No significant relationship emerged between any of the schizotypal scales and negative priming.

Conclusions: It is inferred that negative priming is undisturbed in schizophrenia and schizotypy when unmasked negative priming tasks are employed. Reduced negative priming in previous studies may represent an epi‐phenomenon of short prime presentation times and backward masking.
Measured Internal Temperatures in Concrete Exposed to Outdoor Cyclic Freezing
Authors: Nokken MR , Hooton RD , Rogers CA
Published: May 2004

In this paper, temperature data collected by thermocouples embedded into concrete over a period of 10 years are analyzed for a concrete slab and beam located outdoors near Kingston, Ontario. Temperatures measured in the concrete are compared with temperatures encountered in ASTM C 666 Resistance of Concrete to Rapid Freezing and Thawing and ASTM C 1293 Standard Test Method for Concrete Aggregates by Determination of Length Change of Concrete Due to Alkali-Silica Reaction. The average number of freezing and thawing cycles at the site was counted using different freezing and thawing temperature criteria as presented in the literature by various authors. Results are compared with data from a second site. The rates of freezing and thawing occurring at the outdoor exposure site were found to be significantly less than specified in the ASTM C 666 laboratory test. Average daily maximum temperatures in July were at approximately 33°C at depths of 50 mm in the concrete.
A Soil Column Apparatus for Laboratory Infiltration Study
Authors: Yang H , Rahardjo H , Wibawa B , Leong E-C
Published: May 2004

In this paper, the details of a large-scale soil column apparatus, the procedures for constructing the soil column, and the performance of the apparatus are presented. This paper aims to describe the apparatus that is capable of performing comprehensive infiltration study rather than to describe one particular infiltration study or phenomenon. By using the apparatus, all the variables (pore-water pressures, water contents, inflow rate, and outflow rate) in an infiltration process can be measured instantaneously and automatically, and all the boundary conditions can be controlled. The major instruments for the soil column apparatus consist of a tensiometer-transducer system, data acquisition system, time-domain reflectometry, and electronic weighing balance. By using these instruments, relationships of the volumetric water content versus matric suction of the soil and the infiltration rate versus time at any point of time during an infiltration test can be obtained. The test results also show that the setup functioned properly and suggest that infiltration behavior of any soil configuration (single, two-layered, or multilayered soil) can be studied using this apparatus for different infiltration rates.
A Direct Tensile Strength Testing Method for Unsaturated Geomaterials
Authors: Nahlawi H , Chakrabarti S , Kodikara J
Published: May 2004

The current paper presents a new method for testing direct tensile strength of unsaturated geomaterials, guided by a method developed for concrete testing (Hannant et al. 1999). The developed equipment is used for measurement of direct tensile strength of unsaturated reactive basaltic clay soils and crushed rocks stabilized with cementitious additives. The tensile characteristics of soils were tested at water contents in excess of liquid limit and those close to optimum water content. Stabilized crushed rocks were tested at early and cured states after mixing. Full stress-strain characteristics were measured with the aid of precision transducers and electronic data acquisition. The equipment is capable of measuring tensile strengths of soil slurries (about 1 kPa), as well as cement stabilized crushed rocks (up to about 1 MPa).
The Role of Fine Defect Clusters in Irradiation-Assisted Stress Corrosion Cracking of Proton-Irradiated 304 Stainless Steel
Authors: Busby JT , Sowa MM , Was GS , Kenik EA
Published: May 2004

The influence of small defect clusters on irradiation-assisted stress corrosion cracking (IASCC) of austenitic stainless steels has been examined. A CP-304 SS alloy was irradiated with 3.2 MeV protons to 1.0 dpa at 360°C and then annealed for 45 min. to 1 h at temperatures ranging from 400–600°C. Dislocation microstructure was analyzed using both bright field and dark field techniques and cracking susceptibility was measured in an oxygenated water environment. Intergranular cracking was mitigated following annealing at 500°C/45 min. while only the smallest dislocation loops had been removed. Analysis of the slip step bands on the surface of deformed samples indicates that deformation mode may be important in determining cracking susceptibility. Low-temperature irradiation (< 75°C) was also used to create a high population of small defects without radiation-induced segregation. Samples were then annealed at 350°C for 8 or 15 min. to grow the dislocation loop microstructure, resulting in an irradiated hardness similar to the 1.0 dpa at 360°C case. No segregation was measured in the asirradiated specimens. The change in hardness resulting from 0.3 dpa at 75°C was 73.8 kg/mm2, greater than that for 1.0 dpa at 360°C. Following annealing at 350°C for 8 min., the change in hardness was reduced to 60.8 kg/mm2, similar to 1.0 dpa at 360°C (65.3 kg/mm2). Samples were also strained to 29.6 % strain in an oxygenated water environment at 288°C. No cracking was observed on any specimen. The small defect damage may have been annealed during the constant extension rate test.
Calibration and Testing of On-Line Coal Analyzers
Authors: Rose CD
Published: May 2004

Classical least squares regression is commonly used for straight line fitting in field calibration of coal analyzers. The assumption in using ordinary least squares regression that the independent variable is not subject to error, when in fact both the independent and dependent variables are subject to error, leads to calibration biases. Also, Grubbs' estimators are often used in tests of analyzer measurement precision. The inherent assumption with use of Grubbs methodology for estimating analyzer precision that the analyzer is perfectly calibrated can result in test acceptance of an analyzer that is not measuring anything. This paper proposes use of a latent variables statistical model for both calibration and precision testing. Use of the latent variables model will result in better calibrations and more reliable assessments of analyzer performance. Application is demonstrated using data from a recent analyzer test.
Suicide with a Butcher's Bolt
Authors: Viola L , Costantinides F , Di Nunno C , Battista GM , Di Nunno N
Published: May 2004

The captive bolt pistol is an atypical firearm exclusively produced and used for butchery of breeding animals, but in some rare cases, it has been used as a lethal weapon for committing suicide by butchers, breeders and other people who have access to such weapons during their professional activities. This study describes the suicide committed by a butcher in the province of Udine (N. Italy) in 2001 who shot himself with his own captive bolt pistol that produced in the right temporal region a circular wound and a bone lesion of the temporal squama with a groove involving the frontal lobe; he died five days later of the fatal consequences of the meningo-encephalic lesions. The medico-legal issues implicated in this case, seen in the light of the data reported in the international literature, illustrate the difficulties faced when diagnosing these types of lesions, bearing in mind their rarity and peculiar nature, and introduce elements of differential diagnosis regarding lesions produced by similar weapons that lead to ascertainment of the event as accidental, suicidal, or homicidal.